Datasets:

turingmachine

/

hupd-npe-balanced-same-year-same-class-subset

like 0

ACCEPTED

Dental Treatment Apparatus

Apparatus for dental treatment includes a base, a treatment unit, and a connecting piece. The treatment unit has one or more treatment instruments and one or more lines for the supply of water, air and electricity. The connecting piece is placed in between the base and the treatment unit. The treatment unit can be disconnected from and connected to the base by using the connecting piece.

1. Apparatus for dental treatment, comprising: a base; a treatment unit, said treatment unit being comprised of one or more treatment instruments and one or more lines for supply of water, air and electricity; and a connecting piece positioned between said base and said treatment unit, said treatment unit being able to be disconnected from and connected to said base. 2. Apparatus according to claim 1, wherein said connecting piece is comprised of a first part and a second part, each part being provided with cooperating connector parts for the supply of water, air and electricity, wherein, when the first and second parts are coupled to each other, the connector parts are connected to each other so that a lead-through of water, air and electricity from said base to said treatment unit is established, wherein said second part is provided with an opening through which a drawing pen is movable, said drawing pen at one outer end being fixed to a cable and at another outer end being provided with an inner flanged edge and an outer flanged edge, said outer flanged edge being spaced from said inner flanged edge, wherein a spring is provided in between said inner flanged edge and said second part, said drawing pen being supported on said second part and being drawn against spring force through the opening by said cable, wherein said first part is provided with a first opening having a diameter, said first opening being mobile over said outer flanged edge, while said first opening extends into a second opening, said second opening having a diameter smaller than a diameter of said outer flanged edge but larger that a diameter of said drawing pen, and wherein, when said first part with said second opening is placed in between the flanged edges and leans against the outer flanged edge by pulling said cable, said first part is moved towards said second part, the connector parts being coupled to each other. 3. Apparatus according to claim 2, wherein said second part is provided with a sleeve said drawing pen being movable in said sleeve, while said spring is supported on said second part by said sleeve. 4. Apparatus according to claim 2, wherein said first part or said second part is provided with at least two guide pens, and wherein the part, without at least two guide pens, is provided with at least two guide holes, the guide pens being received in the guide holes, said first part and said second part being connected to each other in a fixed position. 5. Apparatus according to claim 4, wherein the guide pens are conical pens. 6. Apparatus according to claim 4, wherein the guide pens have a length such that outer ends thereof extend beyond said inner flanged edge of said drawing pen when said drawing pen is pushed out by said spring. 7. Apparatus according to claim 4, wherein the guide holes have guide slots extending therein and receive outer ends of the guide pens, and wherein said outer ends of the guide pens are forced into the guide holes when the parts are being connected to each other and said drawing pen is being moved from said first opening into said second opening. 8. Apparatus according to claim 2, wherein the connector parts for the electrical current supply are provided in top of the parts. 9. Apparatus according to claim 2, wherein the connector parts for the supply of the electrical current are provided above the connector parts for the supply of water. 10. Apparatus according to claim 2, wherein the openings are provided centrally in the parts. 11. Apparatus according to claim 2, wherein the inner flanged edge and the outer flanged edge of the drawing pen have a space therebetween, said space being larger than a thickness of said first part, such that said first part fits closely therein between. 12. Apparatus according to claim 2, wherein said inner flanged edge has a diameter larger than a diameter of said first opening in said first part.

The invention relates to an apparatus for dental treatment, comprising a base and a treatment unit, which treatment unit comprises one or more treatment instruments and one or more lines for the supply of water, air and electricity. Such an apparatus is known. The known apparatus has the drawback, that when this has to be serviced or when, as a result of a malfunction, repairs have to be carried out, the entire apparatus is out of use until the activities are completed. It is an object of the present invention to obviate this drawback. The apparatus according to the invention to that end is characterized in that in between the base and the treatment unit a connecting piece is provided by means of which the treatment unit can be disconnected from and connected to the base. With the apparatus according to the invention it is possible to incorporate the technical part of a dental treatment apparatus in a treatment unit and to disconnect this treatment unit from the base. Because of this possibility of disconnection it is possible to provide all the technical parts, and as such, all the parts that are susceptible to malfunction, in a part that is interchangeable. According to a further characteristic of the apparatus according to the invention the connecting piece is formed by a first part and a second part which are provided with cooperating connector parts for the supply of water, air and electricity, whereby, when the two parts are coupled to each other, the connector parts are connected to each other, in such a way that the lead-through of water, air and electricity from the base to the treatment unit is established, whereby the second part is provided with an opening through which a drawing pen is movable, while the drawing pen at one outer end is fixed to a cable and at the other outer end is provided with an inner flanged edge and, spaced there from, an outer flanged edge, whereby in between the inner flanged edge and the second part a spring is provided, by which the drawing pen is supported on the second part and by means of which the drawing pen can be drawn against spring force through the opening by the cable, while the first part is provided with a first opening having a diameter such, that this can be moved over the outer flanged edge, while the first opening extends into a second opening, having a diameter which is smaller than the diameter of the outer flanged edge but which is larger that the diameter of the drawing pen, whereby, when the first part with the second opening is placed in between the flanged edges and leans against the outer flanged edge, by pulling the cable the first part is moved towards the second part, in such a way, that the connector parts are coupled to each other. According to a further characteristic of the apparatus according to the invention the second part is provided with a sleeve in which the drawing pen is movable, while the spring is supported on the second part by means of the sleeve. According to another characteristic of the apparatus according to the invention the one part is provided with at least two guide pens and the other part is provided with at least two guide holes for receiving the guide pens, in such a way that the first part and the second part can be connected to each other in a fixed position. Further features and characteristics will be described with reference to the drawings of an example of an embodiment. The FIGS. 1, 2, 3a and 3b show the two cooperating parts of a connecting piece such as can be used in the apparatus according to the invention, whereby FIG. 1 shows a perspective view of the second part; FIG. 2 shows a perspective view of the first part; FIG. 3a shows a side view of the second part; FIG. 3b shows a side view of the first part. As can be seen in the FIGS. 1 to 3b the connecting piece, such as can be used in the apparatus for dental treatment according to the invention, is formed by a first part 1 and a second part 2 which are provided with cooperating connector parts 4, 9 for the supply of water and air. Further the parts are provided with connector parts 5, 10 for the supply of electricity. When the two parts 1, 2 are coupled to each other the connector parts 4, 9 and the connector parts 5, 10 are connected to each other. In the example of an embodiment shown the first part 1 is provided with three male connector parts 4 for the supply of water and air, and the second part 2 is provided with three female connector parts 9 for the supply of water and air. When the connector parts 4 are connected to the connector parts 9 and when the connector part 5 is connected to the connector part 10, the lead-through of water, air and electricity from the base to the treatment unit is established. When disconnecting the connections between the connector parts 4, 9 the couplings for the water and air supply are automatically closed; because of this no “leak water” and “leak air” can develop. As can be seen in the figures the electronics is led through the upper connector parts 5, 10. Because of this, in case of any “post dripping” after the disconnection of the coupling, no short-circuiting can come about. The second part 2 is provided with a central opening 13 through which a drawing pen 7 is movable, whereby the drawing pen 7 at one outer end 14 is fixed to a cable (not shown) and at the other outer end is provided with an inner flanged edge 15 and, spaced there from, an outer flanged edge 16. In between the inner flanged edge 15 and the second part 2 a spring 8 is provided, by which the drawing pen 7 is supported on the second part 2 and by means of which the drawing pen 7 can be drawn against spring force through the opening 13 by the cable. The first part 1 is provided with a central first opening 3 having a diameter such, that this can be moved over the outer flanged edge 16, while the first opening 3 extends into a second opening 17, having a diameter which is smaller than the diameter of the outer flanged edge 16 but which is larger that the diameter of the drawing pen 7. When the first part 1 with the second opening 17 is placed in between the flanged edges 15, 16 and leans against the outer flanged edge 16, by pulling the cable the first part 1 is moved towards the second part 2, in such a way, that the connector parts 4, 9 and 5, 10 are coupled to each other. In the embodiment shown the second part 2 is provided with a guide sleeve 12 in which the drawing pen 7 is movable, while the spring 8 is supported on the second part 2 by means of the sleeve 12. Further the second part 2 is provided with at least two conical guide pens 11 and the first part 1 is provided with at least two guide holes 6 for receiving the guide pens 11. In the example of an embodiment shown the guide pens 11 have a length such, that the outer ends 19 thereof extend beyond the inner flanged edge 15 of the drawing pen 7 when the drawing pen 7 is pushed out by the spring 8 that is supported by the second part 2. Further guide slots 18 extend into the guide holes 6 for receiving the outer ends 19 of the guide pens 11, in such a way, that when the parts 1, 2 are being connected to each other and when the drawing pen 7 is being moved from the first opening 3 into the second opening 17, the outer ends 19 of the guide pens 11 are forced by means of the guide slots 18 into the guide holes 6. Because of this the female and male connectors for the supply of water, air and electricity will gradually couple with each other. Further, the first part and the second part can be connected to each other in a fixed position. In an advantageous manner the space between the inner flanged edge 15 and the outer flanged edge 16 of the drawing pen 7 is only somewhat larger than the thickness of the first part 1, such that the first part 1 fits closely therein between. In this manner the displacement or tilting of the second part 2 relative to the first part 1 is prevented. Further, in the example of the embodiment the diameter of the inner flanged edge 15 is larger than the diameter of the first opening 3 in the first part, so that is prevented that during the coupling the first part is pushed over the inner flanged edge 15. With the invention it is possible to incorporate the technical part of a dental treatment apparatus in a treatment unit and to disconnect this treatment unit from the base. Because of this possibility of disconnecting it is possible to mount all the technical parts, more in particular the parts that are susceptible to malfunction, in an interchangeable part. When the cable releases the drawing pen 7, the first part 1 will be pushed away from the second part 2 by the force of the pressure spring 8 and by the springs in the water and air connectors 4, 9. The water and air connections automatically are closed after the opening of the coupling. By the three types of connectors that are used it is possible to mount all the electronics in the treatment unit. Because of this it is very simple to interchange only the treatment unit in the case of a breakdown.

20070409

20100601

20080313

64539.0

A61C300

BALLINGER, MICHAEL ROBERT

DENTAL TREATMENT APPARATUS

SMALL

ACCEPTED

A61C

ACCEPTED

Apparatus for Treatment With Magnetic Fields

The invention relates to an apparatus for therapeutic treatment of a patient with magnetic fields, in particular with nuclear magnetic resonances. One object is to provide an apparatus for treatment of a patient with magnetic fields, which in particular allows localized treatment, for example in the head area of the patient, which treatment places as little load as possible on the patient and can be used in a space-saving manner. A further aim is for the apparatus to have the capability to be flexibly matched to the anatomy of the patient and/or of the debilitation. The apparatus has a rest and at least one first cantilever arm (4B), which projects out of the plane defined by the rest (1C), with a device (30B) being arranged on the first cantilever arm (4B) in order to produce the first magnetic treatment field. The apparatus is particularly preferably in the form of a treatment stool or seat.

1. An apparatus for therapeutic treatment of a patient (2) using magnetic fields (B0, B1, 55B, 56B) comprising: at least one first device (30B) for production of a first magnetic treatment field (B0, B1, 55B, 56B) within a first treatment area (50B); a rest (1C) for the patient (2) to lie on, in such a manner that a body region of the patient (2) to be treated is positioned in the first treatment area (50B) once the patient (2) is in place on the apparatus and the apparatus is in an operating position; and at least one first cantilever arm (4B), which projects out of the plane defined by the rest (1C), with the first device (30B) being arranged on the first cantilever arm (4B) in order to produce the first magnetic treatment field, with the apparatus having a movement device (3A, 4A) on which the first and second cantilever arms (4B, 4C) are suspended, in order to move the first and second devices (30B, 30C) essentially along the body axis (1) of the patient (2), and with the movement device (3A, 4A) having at least one rail (9A, 9B), which is attached to the rear face (1G) of the rest (1C), and with the first and second cantilever arms (4B, 4C) being attached to a carriage (8A, 8B) which is arranged on the at least one rail (9A, 9B) such that it can move along the rest (C). 2. The apparatus of claim 1, with the apparatus being in the form of a treatment seat (1), and the rest (1C) being formed by the backrest of the treatment seat (1). 3. The apparatus of claim 1, with the cantilever arm (4B) comprising a contact section (45B), which is at a distance from the rest and on which the first device (30B) for production of the first magnetic treatment field is arranged, and which contact section (45B) is suspended such that it can move, and can make contact with the body region of the patient to be treated. 4. The apparatus of claim 1, with the cantilever arm (4B) being fitted to the apparatus such that it can pivot. 5. The apparatus of claim 1, with the cantilever arm (4B) being designed such that it can pivot on a plane transversely with respect to the rest plane, and making contact with the patient (2) at the side. 6. The apparatus of claim 1, with the cantilever arm having a plurality of joints (44B) which form a joint chain. 7. The apparatus of claim 1, with a stabilization strip being woven through the joint chain. 8. The apparatus of claim 1, with the cantilever arm (4B) having an outer casing, and the first device (30B) for production of the first magnetic treatment field, and the joints (44B) being arranged within the casing. 9. The apparatus of claim 1, with the cantilever arm (4B) having an essentially flat cross section and being able to make contact with the body region of the patient (2) to be treated with its flat face by means of the pivoting process. 10. The apparatus of claim 1, with the apparatus having at least one second cantilever arm (4C) which projects out of the plane defined by the rest (1C), with a second device (30C) for production of a second magnetic treatment field being arranged in a second treatment area (50C) on the second cantilever arm (4C) in such a manner that a body area of the patient (2) can be positioned between the first and second devices (30B, 30C). 11. The apparatus of claim 1, with the apparatus having a third device (30A) for production of a third magnetic treatment field in a third treatment area (50A), with the third device (30A) being arranged on the rest (1C), and with the first, second and third devices (30B, 30C, 30A) being arranged essentially in a U-shape. 12. The apparatus of claim 1, with the first and second devices (30B, 30C) being arranged at the side of the head (2A) of the patient (2) and the third device (30A) being arranged in the area of the back of the head or the spinal column of the patient (2), when the patient is in position on the apparatus and the apparatus is in the operating position. 13-14. (canceled) 15. The apparatus of claim 1, having a locking device (7, 11, 12) in order to lock the movement of the carriage (8A, 8B). 16. The apparatus of claim 1, with the first and second cantilever arms (4B, 4C) being detachably attached to the movement device (3A, 4A) in order to replace the cantilever arms (4B, 4C). 17. The apparatus of claim 1, with the first device (30B) for production of the first magnetic treatment field having at least one first (51B) and second (52B, 53B) magnetic field generator, with the first and second magnetic field generators respectively being in the form of a first and second coil system. 18. The apparatus of claim 1, with the first magnetic treatment field being formed by a superimposition of the magnetic field (B0, B1, 55B, 56B) of the first and second magnetic field generators (51B, 52B, 53B) and with these two magnetic fields being superimposed essentially at right angles in the first treatment area (50B). 19. The apparatus of claim 1, with the first device (30B) for production of the first magnetic treatment field having an essentially flat cross section, and the coils of the first and second coil system being arranged on the same plane as that which forms the coil plane (7-7), with the coil plane being arranged transversely with respect to the rest plane. 20. The apparatus of claim 1, with the first coil system having a basic coil (51B) and the second coil system having two RF coils (52B, 53B). 21. The apparatus of claim 1, with the two RF coils (52B, 53B) being arranged alongside one another and being connected in opposite senses. 22. The apparatus of claim 1, with the two RF coils (52B, 53B) being arranged parallel within the coil opening of the basic coil (51B). 23. The apparatus of claim 1, with the two RF coils (52B, 53B) producing an alternating magnetic field during operation. 24. The apparatus of claim 1, with the first device (30B) for production of the first magnetic treatment field forming an arrangement for production of nuclear magnetic resonance, with the basic coil (51B) producing a basic magnetic field (B0, 55B) during operation, in which the nuclei to be excited precess, and a resonant alternating electromagnetic field (B1, 56B) is injected by means of the RF coils (52B, 53B). 25. The apparatus of claim 1, with the magnetic induction of the basic magnetic field (B0) being between 0.1 Gauss and 1000 Gauss, in particular between 1 Gauss and 100 Gauss. 26. The apparatus of claim 1, having means for periodic production of nuclear magnetic resonances. 27. The apparatus of claim 1, with the repetition frequency of the periodic nuclear magnetic resonance excitation being 1 Hz to 1000 Hz, in particular 5 Hz to 40 Hz. 28-30. (canceled) 31. A method for therapeutic treatment of jaw arthrosis, parodontitis, degenerative jawbone changes or to assist the ingrowth of implants of a living body, the method comprising injecting magnetic fields into the living body. 32. A method for therapeutic treatment of tinnitus of a living body, the method comprising injecting magnetic fields into the living body. 33. A method for cosmetic treatment of a living body, the method comprising injecting magnetic fields into the living body by using the apparatus of claim 1. 34. The method of claim 31, with collagen formation in the living body being achieved by means of magnetic fields.

FIELD OF THE INVENTION The invention relates to an apparatus for therapeutic treatment of a patient using magnetic fields in general, and to an apparatus for treatment with nuclear magnetic resonances in particular. BACKGROUND OF THE INVENTION Non-invasive treatment processes are taking over more and more new fields of application in medicine. With reference to the invention proposed here, apparatuses and methods for therapeutic treatment by means of external magnetic fields should be mentioned in particular. Although, in the past, the precise method of operation of such therapies has not been understood in detail, their therapeutic successes have been scientifically proven and are generally recognized. Investigations relating to the results of known magnetic field therapies can be found, for example, in “Orthopädische Praxis” [Orthopedic Practice] 8/2000, Year 36, pages 510 to 515 and in Fritz Lechner, “Elektrostimulation und Magnetfeldtherapie. Anwendung, Ergebnisse and Qualitätssicherung” [Electrical stimulation and magnetic field therapy. Application, results and quality assurance] 1989. In particular, it has been found during investigations such as these that magnetic field therapies for the patients in some cases produce considerable improvements in the symptoms without any significant verifiable negative side effects. A further major advantage of magnetic field therapies is that they may possibly make it possible to completely avoid an operation, which is associated with considerable pain, risks and costs for the patient. For example, DE 40 26 173 discloses an apparatus which produces pulsed and modulated magnetic fields in order to treat patients. In this case, body tissue is subjected to a magnetic field which is produced by superimposition of a constant magnetic field and an alternating magnetic field. The pulsating fields used there require a large amount of energy and are inert, however, since the coil inductance slows down the field change. The therapeutic effect of this magnetic field therapy comprises inter alia the amelioration of osteoporosis and the consequences of a stroke. In this case, it appears to be probable that the magnetic fields produced promote transport and/or metabolic processes, which lead to a positive therapeutic effect. Until now, it has been assumed that the positive therapeutic effect is caused by an energy exchange between fields and components of cells (protons, ions, etc.). In this case, the energy transfer was explained by the excitation and the absorption of ion cyclotron resonances (ICR) in a biological body, and corresponding ICR conditions were therefore looked for. The known apparatuses are consistently based on the production of ICR conditions. However, this cause explanation and thus the correspondingly designed apparatuses as well in some circumstances appear to be questionable, since cyclotron resonances in general occur only on free particles, for example in a vacuum or in the case of electrons in the conduction band of a semiconductor. Furthermore, it is also possible to show by simple calculation that a cyclotron movement would take place on a circular path whose radius is in its own right greater than the average diameter of the cross section of a human body. This means that an explanation relating to cyclotron resonance may be questionable for the energy transfer, in particular for solid tissue. It is also possible that the effect may be based on piezoelectric processes in the body. This explanation approach assumes that an electrical field exists around every body joint and that, in the healthy state, every movement causes a piezo-voltage, since the cartilage has piezoelectric characteristics. In the debilitated state, these piezo-voltages could be simulated by induced voltages. In this context, see also Christian Thuile, “Das groβe Buch der Magnetfeldtherapie” [The textbook of magnetic field therapy], Linz 1997. A further apparatus for treatment of a biological body with magnetic fields, which produces magnetic resonances within the body to be treated is known from Laid-Open Specification WO 99/66986. The apparatus described there is, however, essentially aimed at carrying out deliberately reproducible treatment with magnetic fields in all biological materials, irrespective of whether ionic parts are present. With the cited apparatus, the positive therapeutic effects are achieved by the production of magnetic resonances and magnetic resonance sequences. However, in this case, nuclear magnetic resonance is also used in particular for energy transfer. Nuclear magnetic resonance methods (so-called NMR methods) have already been known for a long time from other fields of technology. They are used in particular for medical diagnosis and in general for high-precision magnetic-field measurement. With regard to the latter application, the “Virginia Scientific FW101 Flowing Water NMR Teslameter” may be cited by way of example. A description of this appliance can be found at: www.gmw.com/magnetic_measurements/VSI/FW101.html It should also be noted that the known apparatuses for therapeutic medicine generally have large coil systems which are used to generate and modify the magnetic fields. These coil systems have a high inductance, however, which leads to long switching time constants and to high energy consumption. Long switching times disadvantageously lead, however, to low efficiency in terms of dynamic processes in the body. Furthermore, the coil systems are typically designed in such a manner that they have openings into which body parts for example arms or legs, can be introduced. In consequence, the known apparatuses are relatively inelegant and have disadvantages in terms of their storage and transport capabilities. Apart from this, in some cases, they are uncomfortable for the patient. Furthermore, the power consumption of most known apparatuses is very high, since strong magnetic fields are produced by means of the coil systems. Furthermore, orthogonal fields are produced by these known apparatuses with orthogonal coils, that is to say a horizontal cylindrical coil produces a horizontal magnetic field, and a vertical saddle coil produces the vertical field. However, this means that the apparatus may be more than proportionally large, and can be installed only in large medical centers. Furthermore, there remain a series of open questions relating to the physical/physiological operation of the apparatuses and to the processes which they initiate in the body. Without detailed knowledge of the method of operation, however, it has been difficult in the past to determine an optimized design and the optimum parameters for its operation. Recently, apparatuses for therapeutic nuclear magnetic resonance processes have also been used in this field. One such apparatus is known, for example, from WO 02/096514, whose entire contents are hereby included by reference, in particular with respect to the physical principles and medical active mechanisms relating to the subject matter of this disclosure. Particularly with the last-mentioned apparatus, it has already been possible to overcome some of the disadvantages referred to above, and to achieve considerable treatment success. Nevertheless, it has been found that the apparatus can be improved further, for example in terms of its size. Furthermore, the apparatus is not equally well suited to the treatment of all debilitations. In addition, the apparatus can be even better matched to the anatomic characteristics. GENERAL DESCRIPTION OF THE INVENTION The object of the invention is thus to provide an improved apparatus for treatment of a patient with magnetic fields, which in particular allows localized treatment, for example in the head area of the patient, and places as little load as possible on the patient. A further object of the invention is to provide an apparatus such as this which can be used in a space-saving manner. Another object of the invention is to provide an apparatus such as this which can be flexibly matched to the anatomy of the patient and/or to the debilitation, and which gives good treatment results. A further object of the invention is to provide an apparatus such as this which can be manufactured and operated at low cost and is promising and inspires confidence for the patient. The object of the invention is achieved in a surprisingly simple manner just by the subject matter of the independent claims. Advantageous developments of the invention are defined in the dependent claims. According to the invention, an apparatus is proposed for therapeutic treatment of a patient, in particular of a living person or animal, using magnetic fields, which apparatus has at least one first device for production of a first magnetic treatment field. The apparatus defines one or more treatment areas in which a body region of the patient to be treated is positioned, once the patient is in place on the apparatus. The treatment is then carried out by means of the magnetic fields, which are injected into the treatment area or areas. The apparatus also has a rest for the patient to rest on, in particular for the trunk or back of the patient, and has at least one first arm or cantilever arm, which projects at the side from the plane defined by the rest, or from the rest plane, that is to say it runs along the side of the patient transversely with respect to his body axis, with the first device for production of the first magnetic treatment field being arranged on the first cantilever arm, and being located at the side of the patient, away from the rest plane, in an operating position. This results in a relatively small and localized treatment area. Nowadays, it is admittedly assumed that magnetic field treatments such as these have no side effects, or virtually no side effects, but it is nevertheless advantageous to define the treatment area relatively accurately. This represents one of the considerable advantages of the invention. Since the device for production of the first magnetic field can be moved virtually directly to the body surface of the patient—possibly separated only by a textile casing—specific body areas can be treated deliberately. The treatment area and the load on the patient (even if it is only a potential load) are thus reduced to a minimum. The proximity to the patient even results in a multiplication effect. Since it is possible to use smaller coil systems than in the case of known apparatuses, the field curvature is greater, that is to say, overall, the magnetic field has a smaller physical extent, thus further improving the localization of the treatment. The apparatus is preferably in the form of a treatment stool or seat, with the rest being formed by the backrest of the stool or seat, and the cantilever arm being arranged in the area of the patient's head. The use of an adjustable reclining seat, similar to a television comfort seat, has been found to be particularly comfortable for the patient. A treatment apparatus such as this is particularly highly suitable for carrying out treatments in the head area of the patient. This embodiment has the advantage that the apparatus can be used even in relatively small doctor's practices. However, for example, use in relatively large treatment centers is also within the scope of the invention, when the rest is a section of a treatment couch. However, the psychologically advantageous effect of a stool or seat on the patient in comparison to a couch should not be underestimated. Within the scope of the invention, it has been found that treatment in the case of tinnitus patients can result in a noticeable improvement in the symptoms. This is even more surprising because of the fact that little is yet known about the cause of tinnitus and, so far, the main emphasis has been on trials with treatment medication. The apparatus according to the invention has for the first time allowed the head and cervical spine area to be treated, in which case the areas in which the magnetic field treatment is effective may even be restricted—without any restriction to generality—to partial areas of the head, for example the inner ear. This is because it has been found that spinal column damage or blood circulation illnesses may frequently have a cause which can be positively influenced by the apparatus according to the invention. The selective treatment of specific subareas of the brain has, in addition to this, also led to positive results following strokes. Further treatment successes can be achieved in the field of jaw arthrosis, parodontitis (jaw weaknesses) and in the case of degenerative jawbone changes, whose treatment has in the past likewise been focused on traditional therapies, in this case invasive therapies. Furthermore, it has been found that the ingrowth of jaw implants can be assisted. Initial results even lead to the conclusion that there is increased collagen formation in the treatment area, so that the apparatus according to the invention can be used, inter alia, for cosmetic treatment and for skin conditions. The cantilever arm preferably has a contact section which is at a distance from the rest and on which the first device for production of the first magnetic treatment field is arranged, with the contact section being suspended such that it can move, in order to allow it to be moved with the first device and to be applied to the body region of the patient to be treated. According to one advantageously simple refinement of the invention, the cantilever arm has one or more joints, by means of which the cantilever arm is suspended on the apparatus such that it can pivot, in particular on a plane transversely with respect to the rest plane or transversely, in order to produce the movement of the first device for production of the first treatment field, and to apply the contact section to the body. If a plurality of joints are used, these are connected to form a joint chain, thus resulting in high flexibility so that the contact section can be aligned such that it is individually matched to the body shape of the patient, in order to apply this to the patient, for example, over as large an area as possible and at the desired point. In order to provide robustness for the joint chain, it has been found to be advantageous for a strengthening strip to be interwoven in the joint chain. It is also possible to mechanically prestress the cantilever arm towards the patient. According to one advantageous development of the invention, the cantilever arm has an outer textile casing, which preferably allows close contact and encases the first device for production of the first magnetic treatment field, a holding frame on which the first device is mounted, and/or the joints. In consequence, these elements are protected and the apparatus has a pleasant appearance and is convenient. The cantilever arm preferably has an essentially flat cross section, for example being at least twice as high as it is wide, and in particular the pivoting making it possible to apply its flat face to the body region of the patient to be treated. The cantilever arm preferably has a cross section of 1 cm to 20 cm by 2 cm to 40 cm, in particular 2 cm to 10 cm by 5 cm to 25 cm. According to one particular embodiment, the apparatus has at least one second cantilever arm, which is identical to the first cantilever arm but with mirror-image symmetry with respect to the first cantilever arm in relation to the patient, that is to say with the second cantilever arm also projecting out of the rest plane, and with a second device for production of a second magnetic treatment field, which is designed in the same way as the first device, being arranged on the second cantilever arm, in such a way that a body area of the patient, in particular the patient's head, is positioned between the first and the second device once the patient is seated or is in the treatment position. In consequence, the two contact sections can be moved towards one another and away from one another. It is particularly preferable for the apparatus to also have a third device for production of a third magnetic treatment field in a third treatment area, with the third device being arranged in particular on the rest and parallel to it, so that the first, second and third devices form a U-shaped arrangement. The first and second devices are thus advantageously arranged at the side of the patient's head, and the third device is arranged at the rear of the head or on the patient's spinal column, once the patient is seated on the apparatus and the apparatus is in the operating position. This arrangement has made it possible to achieve a considerable improvement in the symptoms, particularly for the treatment of tinnitus. Without any claim that this is the correct answer, this could be a result of both inner ear areas of the patient and specific areas of the head and/or of the spinal column being subjected to treatment at the same time. Furthermore, a movement device can be provided, on which the first and second cantilever arms are suspended, in order to move the first and second devices along the apparatus or body axis of the patient or transversely with respect to the cantilever arms, so that it is possible to treat different body areas of the patient. The movement device is preferably composed of at least one rail and a carriage which can be moved translationally along the rest on this rail, to be precise essentially vertically when the rest is in an upright position, with the rail preferably being attached to the rear piece of the rest. The first and second cantilever arms are also attached to the carriage, so that the first and second devices can be moved along the body axis (axis of symmetry) of the patient. A locking device is preferably also provided, in order to lock the movement of the carriage on the rail. Furthermore, the first and second cantilever arms are preferably detachably attached to the movement device, so that the elongated cantilever arms can be replaced, for example in order to treat other body areas or in order to make it possible to match the apparatus to the body structure of the patient. According to one particularly preferred embodiment, the first, second and/or third devices or device for production of the magnetic field each form or forms an arrangement for production of nuclear magnetic resonance, with a basic coil producing a basic magnetic field during operation, in which the nuclei to be excited precess, and a resonant alternating electromagnetic field is injected by means of two RF coils in each case. The magnetic field treatment is thus carried out in particular by the production of nuclear magnetic resonances (NMR). The nuclear magnetic resonance condition in accordance with the equation ω=γ×B0, where ω is the circular frequency of the alternating RF field, γ is the gyromagnetic ratio of the atom nuclei to be excited, and B0 is the magnetic induction of the basic field, does not need to be explained in any more detail to a person skilled in the art. However, other treatment methods are also possible, for example, by means of constant or alternating magnetic fields. In order to produce NMR, the devices for production of the magnetic treatment fields are preferably in the form of coil arrangements and each have at least one first and second magnetic field generator, in particular in the form of a first and second coil system, respectively. The treatment fields are also each formed by superimposition of the magnetic fields of the respective first and second magnetic field generators, with these two magnetic fields in each case being superimposed essentially at right angles in the associated treatment area. The coils of the respective first and second coil systems are preferably arranged parallel and/or on the same plane, so that the first, second and/or third devices or device each have or has essentially flat cross sections, thus making it possible to achieve a flat design. The plane or coil plane of the first and second devices extends transversely with respect to the rest plane and/or transversely with respect to the body axis of the patient in the operating position, so that side areas of the patient can be treated specifically when the contact sections are applied at the side, for example on the head, of the patient. The coil plane of the third device in contrast runs essentially parallel to the rest plane. The first coil systems each have or comprise a basic coil, and the second coil systems each have or comprise two RF coils, in particular for production of the resonant alternating electromagnetic field for the NMR. Furthermore, the two RF coils are each arranged alongside one another, preferably within the opening in the flat basic coil, and are connected in opposite senses such that, despite the parallel arrangement, the magnetic fields of the first and second coil systems are superimposed centrally and at right angles by means of the respective device. The respective treatment or NMR area is located at a distance of about 1 cm to 30 cm, preferably about 2 cm to 10 cm, and particularly preferably about 3 cm±1 cm from the upper face of the coils. These dimensions have been found to be particularly advantageous for the symptoms to be treated. The magnetic induction of the basic magnetic field of the NMR is preferably between 0.1 Gauss and 1000 Gauss, in particular between 1 Gauss and 100 Gauss. The frequency f of the RF field for hydrogen accordingly corresponds to 422.5 Hz to 4.225 MHz, preferably 4.225 kHz to 422.5 kHz, according to the equation f[kHz]=4.225×B0[Gauss]. The nuclear magnetic resonance is particularly preferably produced periodically, with the repetition frequency of the period nuclear magnetic resonance excitation, preferably being 1 Hz to 1000 Hz, in particular 5 Hz to 100 Hz, and particularly preferably up to 40 Hz, in particular with the RF field being injected discontinuously with this period, for example within a square-wave envelope. The invention will be explained in more detail in the following text using exemplary embodiments and with reference to the drawings, in which identical and similar elements are in some cases provided with the same reference symbols, and features of different exemplary embodiments can be combined with one another. BRIEF DESCRIPTION OF THE FIGURES In the figures: FIG. 1 shows a schematic side view of a treatment seat according to the invention, FIG. 2 shows a schematic plan view from above of the treatment seat in FIG. 1, FIG. 3 shows a schematic rear view of a movement device on the treatment seat, FIG. 4 shows a schematic plan view from above of the movement device shown in FIG. 3 with cantilever arms, FIG. 5 shows a side view, in the form of a detail, of a cantilever arm with a joint chain, FIG. 6 shows a schematic cross section along the line 6-6 in FIG. 7 through a device according to the invention for production of a treatment field, FIG. 7 shows a schematic cross section through the device shown in FIG. 6 along the line 7-7, FIG. 8 shows a photograph of the device shown in FIG. 7, FIG. 9 shows a photograph of a device for production of the treatment field according to a further embodiment of the invention, FIG. 10 shows a block diagram of a controller, FIG. 11 illustrates an example of the time profile of the intensity of the magnetic fields, and FIG. 12 shows a photograph of one embodiment of the treatment seat according to the invention. DETAILED DESCRIPTION OF THE INVENTION With reference to FIG. 1, the apparatus according to the invention for therapeutic treatment with magnetic fields is illustrated in the form of a treatment seat 1. The treatment seat 1 has a foot 1A, a seat surface 1B and a rest or backrest 1C, which defines a rest plane L running essentially parallel to the body axis A. The treatment seat 1 is designed in a similar manner to a relaxing chair, in such a manner that the seat surface 1B can be inclined about a joint 1D, and the backrest 1C can be inclined about a joint 1E in order to provide a comfortable treatment position for the patient. For treatment, the patient 2 (of whom only the head 2A is illustrated for the sake of clarity) sits on the treatment seat 1 and rests his back on the front face 1F of the backrest 1C. A movement device 3 is attached to a rear face 1G (which is opposite the front face 1F) of the backrest 1C, and a holding frame 4 is suspended on this movement device 3 such that it can be moved along the backrest 1C or parallel to the body axis A of the patient 2. The holding frame has a holding section 4A and two mirror-image symmetrical cantilever arms 4B, 4C, of which only the right-hand cantilever arm 4B can be seen in FIG. 1, and with the holding section 4A and the cantilever arms 4B, 4C essentially forming an L-shape or a right angle when viewed from the side. The essentially narrow side cantilever arms 4B, 4C extend like blinkers from back to front or transversely with respect to the body axis A long the patient's head 2A. A device 30B, 30C for production of the treatment field, and in the form of a respective coil arrangement 30B, 30C is respectively attached to the side cantilever arms 4B, 4C. For this purpose, the moving cantilever arms 4B, 4C are, for example, in the form of holding frames composed of nonmagnetic material, and the coil arrangements 30B, 30C are mounted within the respective frame. A third coil arrangement 30C is arranged within the backrest 1C, for example in the area of the back of the head or cervical spine area of the patient 2. Alternatively, the third coil arrangement 30A can also be fitted outside the backrest 1C, on its front face 1F, and can be suspended by means of a holding strip, which runs over the upper face 1H of the backrest 1C and the holding section 4A. In this case, one end of the holding strip is connected to the third coil arrangement 30A, and the second end of the holding strip is connected to the backrest 1C, so that the third coil arrangement 30A is automatically moved together with the holding frame 4 along the body axis A. This embodiment ensures that the three coil arrangements 30A, 30B, 30C remain at least approximately in the same position with respect to one another during movement of the holding frame 4. FIG. 2 illustrates the treatment seat 1 with the patient 2 schematically in the form of a plan view from above, with the illustration likewise showing the coil arrangements 30A, 30B and 30C—although they are concealed in reality. The right-hand cantilever arm or coil cantilever arm 4B is attached by means of a curved connecting section 41B to the holding section 4A, then extends forwards with a straight section 42B, after which it has a jointed section 43B with a plurality of joints 44B, which form a joint chain in order to allow the jointed section to be shaped in a versatile manner. In the illustrated operating position, the jointed section 43B is essentially S-shaped. The coil arrangement 30B is attached to an essentially straight contact section 45B which is at a distance from the holding section 4A and is adjacent to the jointed section 44B. The contact section 45B (which is located at the front end of the cantilever arm 4B) as well as the coil arrangement 30B in this example extend obliquely forward and inward from above, in a plan view, in order to treat the left-hand and right-hand areas of the face, and the coil arrangements 30A, 30B and 30C form a U-shape, or run along the sides of a triangle. The coils are thus arranged in such a manner that the magnetic lines of force each emerge from the coils transversely with respect to the rest and transversely with respect to the body axis A. The joints 44B allow the cantilever arm 4B to be moved away from the patient's head 2A and back toward it again, to be more precise to be pivoted along the arrow 46B in such a manner that the contact section 45B can be moved with the coil arrangement 30B, to be precise can be moved away from the patient and toward the patient. The coil arrangements 30B, 30C can thus be moved at least two-dimensionally by the combination with the movement device 3. In the operating position, the contact section 45B is located at the body region of the patient 2 to be treated, or is located at least in its immediate proximity. The contact section 45B together with the coil arrangement 30B arranged in it is surrounded by a textile casing, plastic casing or some other cladding materials, although this is not illustrated in the figures. The overall arrangement is mirror-image symmetrical around the axis of symmetry B of the patient, so that the left-hand cantilever arm 4C and the left-hand coil arrangement 30C are identical, but in mirror-image form. Each of the three coil arrangements 30A, 30B and 30C produces a basic magnetic field B0 and an RF field B1, which are superimposed essentially at right angles to the respective treatment area, in the respective treatment area 50A, 50B, 50C, with at least parts of these treatment areas being located in the interior of the patient's body. In this case, the treatment areas 50A, 50B, 50C each face one another on the inside and face the patient. In other words, the body region of the patient to be treated is located within the respective treatment area. The three treatment areas cannot, of course, be delineated exactly and are thus illustrated only schematically by means of dashed lines with the reference symbols 50A, 50B and 50C. The size and position of the respective treatment areas 50A, 50B and 50C may vary within certain limits as a result of the tuning of the magnetic fields. The three treatment areas 50A, 50B, 50C may, of course, also overlap to form a common treatment area. FIG. 3 shows a rear view of the holding frame 4. The holding frame 4 has the holding section 4A, an upper, middle and lower transverse strut 4B, 4C, 4D and two movement rails 8A, 8B, which form a movement carriage 8C. The movement carriage 8C slides on a rail in the form of an adaptor plate 3A, which is attached to the rear face 1G of the backrest 1C. The adaptor plate 3A has a plurality of vertically arranged holes 11, in which a latching pin, which is fitted on a pull-button 7, latches as a locking means in the respectively desired position, in order to lock the movement of the holding frame 4. The pull-button 7 is in this case arranged in the area of the movement handle 6, in order to ensure easy handling. For servicing and repair purposes or for other medical indications, the holding frame 4 can be removed together with the cantilever arms 3B and 3C from the seat 1, and can be replaced. This is done by releasing a lock and by pulling the movement carriage 8C upward along the rails. An adjusting handle 6 for manual movement of the holding frame 4 is also permanently fitted to the holding section 4A. FIG. 4 shows a cutaway plan view from above of the movement mechanism and the cantilever arms without the textile sheath. In particular, the illustration shows how the movement rails 8A, 8B can be moved on the movement rails 9A, 9B of the adaptor plate, with balls 10 forming a ball bearing. This also illustrates how the latching pin 12 engages in the hole 11 in the hole pattern. The figure also shows the capability to move the cantilever arms 30B, 30C transversely in a flexible manner by means of the joint 44B and link elements 14, 15 located between them, which together form the joint chain of each cantilever arm. The cantilever arms 30B, 30C are detachably attached to the common holding section 4A by attachment means which are not illustrated. FIG. 5 shows a side view of the link elements 14, 15, which are connected to one another in pairs by means of compression elements 17, compression rings 18, washers 19 and nuts 20, in a slightly clamped manner such that they can rotate. The figure also shows an electrical supply line 21 for the coil arrangements. FIG. 6 shows the coil arrangement 30B, representing all three identical coil arrangements 30A, 30B, 30C schematically in the form of a cross section parallel to the coil plane. The coil arrangement 30B has a basic coil 51B for production of the virtually constant basic field BO, whose magnetic lines of force 55B emerge centrally at right angles from the coil arrangement 30B, as well as two RF coils 52B, 53B. The two RF coils 52B, 53B are polarized in opposite senses, so that the magnetic lines of force 56B of the alternating magnetic field B1 emerge upward on the upper face of the left-hand RF coil 53B, and enter the coil arrangement again on the upper face of the right-hand RF coil 52B. In the treatment area 50B, this results in the magnetic fields B0 and B1 produced by means of coils 51B, 52B, 53B (which are arranged parallel) being essentially at right angles to one another despite the fact that they emerge from the coils parallel, thus making it possible to satisfy the nuclear magnetic resonance conditions in the treatment area 50B. FIG. 7 shows a section illustration along the line 7-7 in FIG. 6, with the line 7-7 representing the coil plane. 6-6 shows the section line for the illustration in FIG. 6. As can be seen from FIG. 7, the two RF coils 52B, 53B are arranged within the opening 54B to the basic coil 51B. The planar arrangement of the basic coils 51B and of the RF coils 52B and 53B according to the invention makes it possible to generate orthogonal magnetic fields in the treatment area. In this case, in the treatment area, the basic or sweep coil 51B produces the virtually constant magnetic field BO, which is vertical with respect to the coil plane, and the two radio-frequency coils 52B, 53B within the sweep coil produce the alternating magnetic field B1, which is parallel to the coil plane, in the treatment area. The shape of the coil arrangement can also be matched appropriately to the application and the body shape, for example it can be curved for joint damage. An embodiment of the invention such as this (not illustrated) has been proven in particular for the treatment of animals. For example, the coil arrangement can be attached to a gaiter, in particular by being stapled to it, which can be used, for example, for the treatment of horse fetlocks. A soft treatment cover has also been successfully used, which is placed over the back of a horse and to which one or more coil arrangements can be detachably attached, for example by means of a Velcro strip, at any desired point. The RF coils 52B, 53B furthermore have a series inductance L and, together with a capacitor C, form a tuned circuit. The electrical natural resonant frequency F is given by: F = 1 2   π  LC In this case, the natural resonant frequency and the nuclear magnetic resonance frequency are matched to one another so that the RF transmitter in the controller automatically generates an AC voltage at the frequency F, in order to produce alternating fields that are as large as possible, with a relatively small amount of energy. Each of the coil arrangements 30A, 30B, 30C produces the two orthogonal magnetic fields B0 and B1 which are in each case required for the nuclear magnetic resonance process, in accordance with the equation which is applicable to protons, which make up about 80% of the atom nuclei which occur in human and animal bodies: f[kHz]=4.225×B0[Gauss] The magnetic treatment area BO is in this case composed of a constant or static component B01 and a smaller modulation component B02, that is to say B0 is virtually constant. The frequency f is in this case tuned to the constant component B01. By way of example, B01=4 Gauss, and the frequency f=16.9 kHz. The magnitude of the variable magnetic field component B02 is about 10% to 100%, preferably 20% to 70%, and most preferably about 50%±10% of the magnitude of B01. The variation of the modulation component B02 compensates for the inhomogeneity of B01. In other words, the basic magnetic field B0 is modulated in such a manner that the nuclear magnetic resonance condition is satisfied, at least at times, over the entire treatment area. In other words, the natural inhomogeneity of B0 in conjunction with the modulation by means of B02 is used in order to scan the resonance condition over the treatment area. FIG. 8 shows a photograph of the coil arrangement 30B with dimensions. The coil arrangement has a length of L=116 mm, a width B=68 mm and a height H=15 mm. The opening in each of the essentially square RF coils 52B, 53B is about 42 mm square. However, a variation of the size to a range from about one twentieth, one fifth, one third or one half up to about twice, three times, five times or twenty times a stated dimension is also within the scope of the invention. FIG. 9 shows an alternative embodiment of the coil system with essentially circular RF coils and an oval basic coil around the RF coils. Furthermore, a tuning element 57B is provided, and is fitted within the coil arrangement. The tuning element 57B is used to detect the NMR signal and to match the basic field B0 and/or the RF field B1, so as to form a control loop for controlling the magnetic fields for nuclear magnetic resonance. FIG. 10 shows a block diagram of the control electronics. A logic module 62 controls a drive device 64 for the basic or sweep coil 51B, and a drive device 66 controls the two RF coils 52B, 53B, which are connected in series. Furthermore, the apparatus is supplied with electrical power from a power supply unit 68. The controller can in this case drive one, two, three or more coil arrangements. FIG. 11 shows an example of a magnetic field profile for periodic nuclear magnetic resonance production. The basic field B0 has a constant basic level B01 and a component B02 which varies with time, in this example corresponding to triangular-waveform modulation. The alternating field B1 is injected discontinuously and periodically with a square-wave envelope during the falling flanks of the basic field B0. In other words, the alternating field B1 is active on the falling flanks B0, and is equal to zero on the rising flanks, which is also referred to as a fast adiabatic passage. The hydrogen nucleus magnetization in the body is in this case tilted through 180° in each case. Table 1, below, shows particularly advantageous values for treatment. TABLE 1 Alternating field (B1) 2 kHz to 40 kHz, in particular about 30 kHz B1 amplitude 0.02 mT to 0.15 mT, in particular about 0.05 mT Virtually-constant magnetic 30 mm above the coil system field (B01) 0.1 mT to 1.0 mT, in particular about 0.7 mT Magnetic field sweep (B02) 20% to 50% of B01, in particular about 30% Modulation frequency of B02 1 Hz to 250 Hz Modulation type of B02 Triangular, square-wave, sinusoidal, triangular particularly preferable However, frequencies of the alternating field B1 of 5 kHz to 1 MHz have also been proven for larger coil arrangements. It is obvious to a person skilled in the art that the embodiments described above should be regarded only as examples and the invention is not restricted to them, but can be varied in many ways without departing from the essence of the invention.

<SOH> BACKGROUND OF THE INVENTION <EOH>Non-invasive treatment processes are taking over more and more new fields of application in medicine. With reference to the invention proposed here, apparatuses and methods for therapeutic treatment by means of external magnetic fields should be mentioned in particular. Although, in the past, the precise method of operation of such therapies has not been understood in detail, their therapeutic successes have been scientifically proven and are generally recognized. Investigations relating to the results of known magnetic field therapies can be found, for example, in “Orthopädische Praxis” [Orthopedic Practice] 8/2000, Year 36, pages 510 to 515 and in Fritz Lechner, “Elektrostimulation und Magnetfeldtherapie. Anwendung, Ergebnisse and Qualitätssicherung” [Electrical stimulation and magnetic field therapy. Application, results and quality assurance] 1989. In particular, it has been found during investigations such as these that magnetic field therapies for the patients in some cases produce considerable improvements in the symptoms without any significant verifiable negative side effects. A further major advantage of magnetic field therapies is that they may possibly make it possible to completely avoid an operation, which is associated with considerable pain, risks and costs for the patient. For example, DE 40 26 173 discloses an apparatus which produces pulsed and modulated magnetic fields in order to treat patients. In this case, body tissue is subjected to a magnetic field which is produced by superimposition of a constant magnetic field and an alternating magnetic field. The pulsating fields used there require a large amount of energy and are inert, however, since the coil inductance slows down the field change. The therapeutic effect of this magnetic field therapy comprises inter alia the amelioration of osteoporosis and the consequences of a stroke. In this case, it appears to be probable that the magnetic fields produced promote transport and/or metabolic processes, which lead to a positive therapeutic effect. Until now, it has been assumed that the positive therapeutic effect is caused by an energy exchange between fields and components of cells (protons, ions, etc.). In this case, the energy transfer was explained by the excitation and the absorption of ion cyclotron resonances (ICR) in a biological body, and corresponding ICR conditions were therefore looked for. The known apparatuses are consistently based on the production of ICR conditions. However, this cause explanation and thus the correspondingly designed apparatuses as well in some circumstances appear to be questionable, since cyclotron resonances in general occur only on free particles, for example in a vacuum or in the case of electrons in the conduction band of a semiconductor. Furthermore, it is also possible to show by simple calculation that a cyclotron movement would take place on a circular path whose radius is in its own right greater than the average diameter of the cross section of a human body. This means that an explanation relating to cyclotron resonance may be questionable for the energy transfer, in particular for solid tissue. It is also possible that the effect may be based on piezoelectric processes in the body. This explanation approach assumes that an electrical field exists around every body joint and that, in the healthy state, every movement causes a piezo-voltage, since the cartilage has piezoelectric characteristics. In the debilitated state, these piezo-voltages could be simulated by induced voltages. In this context, see also Christian Thuile, “Das groβe Buch der Magnetfeldtherapie” [The textbook of magnetic field therapy], Linz 1997. A further apparatus for treatment of a biological body with magnetic fields, which produces magnetic resonances within the body to be treated is known from Laid-Open Specification WO 99/66986. The apparatus described there is, however, essentially aimed at carrying out deliberately reproducible treatment with magnetic fields in all biological materials, irrespective of whether ionic parts are present. With the cited apparatus, the positive therapeutic effects are achieved by the production of magnetic resonances and magnetic resonance sequences. However, in this case, nuclear magnetic resonance is also used in particular for energy transfer. Nuclear magnetic resonance methods (so-called NMR methods) have already been known for a long time from other fields of technology. They are used in particular for medical diagnosis and in general for high-precision magnetic-field measurement. With regard to the latter application, the “Virginia Scientific FW101 Flowing Water NMR Teslameter” may be cited by way of example. A description of this appliance can be found at: in-line-formulae description="In-line Formulae" end="lead"? www.gmw.com/magnetic_measurements/VSI/FW101.html in-line-formulae description="In-line Formulae" end="tail"? It should also be noted that the known apparatuses for therapeutic medicine generally have large coil systems which are used to generate and modify the magnetic fields. These coil systems have a high inductance, however, which leads to long switching time constants and to high energy consumption. Long switching times disadvantageously lead, however, to low efficiency in terms of dynamic processes in the body. Furthermore, the coil systems are typically designed in such a manner that they have openings into which body parts for example arms or legs, can be introduced. In consequence, the known apparatuses are relatively inelegant and have disadvantages in terms of their storage and transport capabilities. Apart from this, in some cases, they are uncomfortable for the patient. Furthermore, the power consumption of most known apparatuses is very high, since strong magnetic fields are produced by means of the coil systems. Furthermore, orthogonal fields are produced by these known apparatuses with orthogonal coils, that is to say a horizontal cylindrical coil produces a horizontal magnetic field, and a vertical saddle coil produces the vertical field. However, this means that the apparatus may be more than proportionally large, and can be installed only in large medical centers. Furthermore, there remain a series of open questions relating to the physical/physiological operation of the apparatuses and to the processes which they initiate in the body. Without detailed knowledge of the method of operation, however, it has been difficult in the past to determine an optimized design and the optimum parameters for its operation. Recently, apparatuses for therapeutic nuclear magnetic resonance processes have also been used in this field. One such apparatus is known, for example, from WO 02/096514, whose entire contents are hereby included by reference, in particular with respect to the physical principles and medical active mechanisms relating to the subject matter of this disclosure. Particularly with the last-mentioned apparatus, it has already been possible to overcome some of the disadvantages referred to above, and to achieve considerable treatment success. Nevertheless, it has been found that the apparatus can be improved further, for example in terms of its size. Furthermore, the apparatus is not equally well suited to the treatment of all debilitations. In addition, the apparatus can be even better matched to the anatomic characteristics.

<SOH> BRIEF DESCRIPTION OF THE FIGURES <EOH>In the figures: FIG. 1 shows a schematic side view of a treatment seat according to the invention, FIG. 2 shows a schematic plan view from above of the treatment seat in FIG. 1 , FIG. 3 shows a schematic rear view of a movement device on the treatment seat, FIG. 4 shows a schematic plan view from above of the movement device shown in FIG. 3 with cantilever arms, FIG. 5 shows a side view, in the form of a detail, of a cantilever arm with a joint chain, FIG. 6 shows a schematic cross section along the line 6 - 6 in FIG. 7 through a device according to the invention for production of a treatment field, FIG. 7 shows a schematic cross section through the device shown in FIG. 6 along the line 7 - 7 , FIG. 8 shows a photograph of the device shown in FIG. 7 , FIG. 9 shows a photograph of a device for production of the treatment field according to a further embodiment of the invention, FIG. 10 shows a block diagram of a controller, FIG. 11 illustrates an example of the time profile of the intensity of the magnetic fields, and FIG. 12 shows a photograph of one embodiment of the treatment seat according to the invention. detailed-description description="Detailed Description" end="lead"?

20070410

20090428

20080612

89496.0

A61N202

LACYK, JOHN P

APPARATUS FOR TREATMENT WITH MAGNETIC FIELDS

SMALL

ACCEPTED

A61N

ACCEPTED

Luminous Body

A luminous body is described, in particular in the form of a planar lighting device for general lighting or for back-lighting of displays, which luminous body comprises a plurality of light sources (2), for example LED elements, arranged in a housing (10), in particular an optical waveguide plate (1). The optical waveguide plate (1) forms a first optical medium (1) with a first optical scattering power, into which the light of the light sources (2) is coupled. Furthermore, at least one second optical medium (5) with a second optical scattering power is provided, such that the light propagating in the second optical medium (5) is at least substantially coupled in from the first optical medium (1), and the scattering power of at least one of the media is chosen for the purpose of influencing the flow of light in the housing (10) such that a given brightness distribution of the light on the light emission surface (4) is achieved.

1. A luminous body comprising a housing (10) with a light emission surface (4) and a plurality of light sources (2) arranged in the housing (10), wherein the housing (10) comprises at least a first optical medium (1) with a first optical scattering power, into which medium (1) the light of the light sources (2) is coupled, and at least a second optical medium (5) with a second optical scattering power, such that the light propagating in the second optical medium (5) is at least substantially coupled thereinto from the first optical medium (1), and wherein the scattering power of at least one of the media is chosen with a view to influencing the flow of light in the housing (10) such that a predefinable brightness distribution of the light over the light emission surface (4) is achieved. 2. A luminous body as claimed in claim 1, with at least one layer (3) by means of which the second optical medium (5) is screened off at least substantially against a direct incidence of the light originating from a light source (2). 3. A luminous body as claimed in claim 2, wherein the layer (3) is a layer that reflects on both sides. 4. A luminous body as claimed in claim 1, wherein the second optical medium (5) is introduced into a region between at least one light source (2) and the light emission surface (4). 5. A luminous body as claimed in claim 1, wherein the first optical medium is an optical waveguide plate (1), and the light sources (2) are arranged in at least one cavity (8) of said optical waveguide plate (1). 6. A luminous body as claimed in claim 5, wherein the scattering power of the second optical medium (5) is chosen such that it compensates at least substantially for the reduction in the flow of light in the first optical medium (1) caused by at least one of the cavities (8) provided in the first optical medium (1). 7. A luminous body as claimed in claim 5, wherein the second optical medium (5) is introduced into at least one region between at least one cavity (8) and the light emission surface (4). 8. A luminous body as claimed in claim 1, wherein the second optical medium (5) comprises light-scattering particles. 9. A luminous body as claimed in claim 8, wherein the light-scattering particles are globules with an optical refractive index different from that of the surrounding material. 10. A luminous body as claimed in claim 8, wherein the light-scattering particles are regions created by a material change caused by the action of at least one laser beam.

The invention relates to a luminous body, in particular in the shape of a planar lighting device for general lighting or for backlighting of displays, which luminous body comprises a plurality of light sources, for example LED elements, arranged in a housing, in particular an optical waveguide plate. Luminous bodies are preferentially used with a light emission surface (coupling-out layer) extending over at least one of their surfaces for realizing planar lighting devices that extend in a plane. The light may then be generated both by point-shaped and by linear light sources in the luminous body. In particular, LED elements and fluorescent lamps may be used. The aim in dimensioning these luminous bodies is to achieve not only as high as possible an efficiency, i.e. the lowest possible reflection losses in the luminous body, but also as even as possible a distribution of the luminous intensity over the light emission surface. Various embodiments of such luminous bodies, and in particular various arrangements of the light sources in or at a housing or optical waveguide plate are known for achieving these aims. Thus it is known, for example, to arrange the light sources along side walls of the optical waveguide plate (side-lit arrangement), so that light is coupled into the plate and is propagated therein by total reflection against the main surfaces and the side faces perpendicular thereto of the optical waveguide plate. A coupling-out layer at one of the main surfaces causes the light to be radiated to the exterior. It is furthermore known to provide a plurality of cavities, each containing a light source, in an optical waveguide plate. The cavities each have an upper side facing the light emission surface of the optical waveguide plate and side walls. The upper side of each cavity is covered with a reflecting layer, so that the coupling of the light generated by the light source present in the cavity into the optical waveguide plate takes place exclusively through the side walls of the cavity (cavity-lit arrangement). Alternatively, light sources may be used which radiate the light exclusively in a direction parallel to the light emission surface of the optical waveguide plate. A comparatively homogeneous mixing and distribution of the light of each individual light source over the light emission surface of the luminous body can be achieved with these arrangements, and an even illumination can accordingly be obtained. Finally, so-called direct-lit arrangements are known, wherein the individual light sources are inserted into a common housing whose side walls are manufactured from a highly reflective material or are coated with such a material, while the upper side of the housing is coated with a diffuser layer, so that the light from the light sources leaves the diffuser layer (light emission surface) of the luminous body in a comparatively homogeneous manner. These arrangements each have their various advantages and disadvantages. Thus the light can be propagated evenly and without disturbance in the optical waveguide plate in the side-lit arrangement mentioned above, so that it also distributes itself comparatively homogeneously over the light emission surface, but the achievable brightness of the luminous body is limited because only a limited number of light sources can be accommodated along the edge of the optical waveguide plate. In the cavity-lit and direct-lit arrangements, by contrast, a substantially larger number of light sources can indeed be used in relation to the surface area of the luminous body, but here special measures are necessary for ensuring that the achieved luminous intensity is accompanied by a sufficiently high or desired homogeneity on the light emission surface. It is accordingly an object of the invention to provide a luminous body of the kind mentioned in the opening paragraph with which a particularly homogeneous illumination of the light emission surface can be achieved in combination with a comparatively high luminous intensity. Furthermore, a luminous body of the kind mentioned in the opening paragraph is to be provided with which a very homogeneous illumination of the light emission surface can be achieved also with only a small constructional depth. Finally, a luminous body of the kind mentioned in the opening paragraph is to be provided wherein the individual light sources are not recognizable, or are so only to a very low degree, on the light emission surface of the luminous body, in particular in the case in which the luminous body has only a small constructional depth. According to claim 1, the object is achieved by means of a luminous body comprising a housing with a light emission surface and a plurality of light sources arranged in the housing, wherein the housing comprises at least a first optical medium with a first optical scattering power, into which medium the light of the light sources is coupled, and at least a second optical medium with a second optical scattering power, wherein the light propagating in the second optical medium is at least substantially coupled thereinto from the first optical medium, and wherein the scattering power of at least one of the media is chosen with a view to influencing the flow of light in the housing such that a predefinable brightness distribution of the light over the light emission surface is achieved. A particular advantage of this solution is that the light-scattering media are capable of substantially completely compensating for disturbances in the propagation of the light in the housing (which would lead to darker regions on the light emission surface above the usually shaded light sources) caused by the light sources (or by the cavities provided in the optical waveguide plate for accommodating the light sources), so that the light reaches the light emission surface with a substantially more homogeneous intensity distribution. The principle of this solution accordingly is not that the light directly originating from the light sources is homogenized, as in the prior art, but that the disturbed or reduced flow of light in the optical waveguide plate in the regions of the light sources (or cavities) can be compensated by an enhanced coupling-out of light from the relevant regions. This is of advantage in particular with luminous bodies of small constructional depth, because here it is particularly difficult to homogenize the light that directly issues from the light sources. Furthermore, the requirements imposed on the light emission surface or the coupling-out layer as regards their light-scattering properties can also be substantially reduced thereby. The light emission surface or the coupling-out layer can accordingly serve substantially exclusively for generating a desired distribution or modulation of the luminous intensity (for example with brighter and darker regions). Overall, therefore, the solution according to the invention combines the advantages of the side-lit arrangement mentioned above as regards the homogeneity of the light distribution on the light emission surface with the advantages of the cavity-lit and the direct-lit arrangements as regards the achievable high luminous intensity, without having to accept their respective substantial disadvantages. The light sources used may be both substantially point-shaped and linear light sources, or a mixture of both kinds of light sources such as, in particular, LEDs and/or fluorescent lamps. The advantages mentioned above come into their own in particular when colored light sources (for example colored LEDs) are used, because a desired color or mixed color can be generated with a high degree of homogeneity and evenness. The dependent claims relate to advantageous further embodiments of the invention. The embodiment of claim 2 gives a particularly high degree of certainty that the light will be coupled into the second optical medium exclusively from the first optical medium and not from one of the light sources. It is achieved thereby in particular that the light sources do not become recognizable even in the form of only slightly brighter regions on the light emission surface. It is possible with the embodiments of claims 3, 5, and 7 to increase also the efficiency of the luminous body. The embodiments of claims 4, 6, and 7 also provide a further improvement of the light distribution over the light emission surface. The embodiments of the second optical medium of claims 8 to 10 render possible a very exact optimization of the scattering power as regards a homogeneous, or alternatively a desired, possibly non-homogeneous light distribution over the light emission surface. Further details, features, and advantages of the invention will become apparent from the ensuing description of preferred embodiments which is given with reference to the drawing, in which: FIG. 1 is a diagrammatic cross-sectional view of a luminous body according to the invention; and FIG. 2 is a diagrammatic plan view of the luminous body shown in FIG. 1. FIG. 1 is a diagrammatic cross-sectional view of a luminous body according to the invention in the form of a substantially flat or planar light source. The luminous body comprises a housing 10 whose walls are preferably coated with a diffusely highly reflective material. Inside the housing 10 there is an optical waveguide plate 1 which forms a first optical medium with a first optical scattering power. The optical waveguide plate 1 is made, for example, from plexiglas and has a depth (thickness), for example, of approximately 10 to 15 mm and a length and width corresponding to the desired dimensions of the luminous body. Instead of the optical waveguide plate 1, the first optical medium may alternatively be air or some other gas. The light is issued at a light emission surface 4, which has a scattering coupling-out layer and closes off the housing 10 at its upper side. An air gap is preferably present between the lower side (rear wall 7) of the optical waveguide plate 1 opposed to the upper side and the bottom of the housing 10, so that the light is totally reflected there. A plurality of light sources 2 is recessed into the rear wall 7. The light sources 2 are fastened to the rear wall 7 and are contacted in a usual manner. The light sources 2 radiate light either in all directions, or they are constructed such that they radiate the light substantially in lateral directions only, i.e. parallel to the light emission surface 4 or the optical waveguide plate 1. The light sources 2 are either substantially point-shaped, preferably forming light-emitting diodes (LEDs), which are known and can be used, for example, with an electrical power rating of 1 and 5 W and in the colors blue, green, red, and white. Linear light sources may also be used, alternatively or in addition thereto. A plurality of cavities 8 is provided in the optical waveguide plate 1 for accommodating the light sources 2. As is further apparent from FIG. 1, a second optical medium 5 having a second optical scattering power, which is preferably higher than the first scattering power of the first optical medium 1, is present in the space between the respective cavities 8 and the light emission surface 4. The second optical media 5 are made from a material such that they diffusely reflect the light incident thereon. The material and the dimensions of the second optical media are arranged and chosen such that they, on account of their scattering power, provide a compensation for the reduction in the flow of light in the optical waveguide plate 1 caused by the respective cavities 8 against which they are arranged, i.e. they increase the incidence of light on the light emission surface 4 in the regions above the respective cavities 8 such that this incidence of light corresponds to the incidence of light in the other regions, whereby a homogeneous or even brightness distribution on the light emission surface 4 is achieved. As FIG. 1 shows, therefore, either a comparatively strongly scattering second optical medium 5 of comparatively small size or a comparatively weakly scattering second optical medium 5 (but still more strongly scattering than the first optical medium 1) of correspondingly larger dimensions may be used. The second optical media 5 preferably extend over the entire surface of each cavity 8 facing the light emission surface 4, as is shown in FIG. 1. The light-scattering properties of the second optical media 5 may be achieved, for example, in that they comprise a dispersion of scattering particles such as, for example, hollow globules with a refractive index different from that of the remaining material of the medium 5. The scattering properties of the second optical media 5 can be optimized to the given dimensioning of the optical waveguide plate and its cavities in a comparatively simple manner through a suitable choice of the size of the particles and of the material from which they are manufactured, i.e. the refractive index thereof, and their number or density in the second optical media 5, so that a desired distribution (homogeneous or otherwise) of the luminous intensity on the light emission surface 4 is achieved. Furthermore, the light-scattering second optical media 5 may also be created through laser engraving, wherein the focus of at least one laser beam changes the material of the second medium 5 in certain locations in a given manner, such that its scattering property is generated in a desired manner. The coupling-out of light from the cavities 8 accommodating the light sources 2 can be substantially increased by means of these second optical media 5, as was noted above, so that the reduction in the flow of light through the cavities 8 can be compensated for. Given a suitable choice of the second optical media 5 in accordance with the above discussion, the modulation of the light emission surface 4 or the coupling-out layer, which usually serves for homogenizing the light distribution, can be considerably reduced or even omitted, which also renders it possible to reduce the manufacturing cost of the luminous body. On the other hand, a given (non-homogeneous) light distribution can now be generated in a substantially simpler manner through modulation of the light emission surface 4 or the coupling-out layer. It may similarly be achieved through a suitable choice of the light-scattering properties of the second optical media 5 that the regions of the cavities 8 (i.e. of the light sources 2) appear more brightly on the light emission surface 4 in comparison with their surroundings. Alternatively, these regions may also be made to appear darker, for example if the scattering power of the second optical medium 5 is lower than the scattering power of the first optical medium 1. A further alternative is that the light-scattering properties of individual or all second optical media 5 are electrically controlled, so that certain lighting effects can be achieved in this manner. For example, a user may switch over in this manner between a homogeneous luminous surface and a weakly luminous surface with bright dotted lines or circles integrated therein. The surfaces of the cavities 8 facing (opposite) the light emission surface 4 each have a reflecting layer 3 which is dimensioned such that the light originating from the light sources 2 cannot directly hit the second optical media 5, but is reflected back from the layer 3 into the cavities 8 and into the first optical medium 1 (optical waveguide plate), from where it enters in part into the second optical media 5. The layer 3 is preferably reflecting not only at the side facing the light source 2, but also on the other side, so as to improve the flow of light further. The layer 3 may also be provided directly on the second optical media 5. The light emission surface 4 of the luminous body is formed by a diffusely scattering plate (diffuser plate), for example semi-transparent, whose degree of transmission preferably lies below 50% but may also be locally variable so as to achieve a given brightness distribution of the generated light. FIG. 2 is a plan view of such a luminous body, wherein the light emission surface 4 or coupling-out layer has been removed for making the arrangement of the light sources (in this case of the second optical media 5) visible. As is apparent from this Figure, the light sources are provided on the rear wall 7 in a regular arrangement, with spacings between them of preferably between approximately 1 and 5 cm if the LEDs mentioned above are used. It is possible with this arrangement to realize a planar radiator with a very high homogeneity of the light distribution over the light emission surface 4 also in the case of a small constructional depth (i.e. the distance between the rear wall 7 and the light emission surface 4) of, for example, 10 to 15 mm and a comparatively large interspacing of the individual light sources 2 of, for example, 1 to 5 cm. Experiments have shown that an average intensity deviation of the light on the light emission surface 4 of well below 10% can be achieved without problems. In particular, the distance between the individual LEDs may then be approximately 2.5 to 5 times the constructional depth of the luminous body. The lateral emission of the light from the cavities 8 causes the emitted light to be reflected mainly at the upper side of the rear wall 7 and the lower side of the light emission surface 4 in the case in which a gas is used as the first optical medium, i.e. with a wide angle of incidence each time, so that particularly low reflection losses occur and a high homogeneity on the light emission surface 4 and a high efficiency of the luminous body are achieved by the second optical media 5 also in this case. Experiments have shown that luminance values of the luminous body of up to 20,000 cd/m2 can be achieved with commercially available LEDs. When known white LEDs with an electrical power rating of 1 W are used, these luminance values lie at approximately 4000 cd/m2. This renders it possible to fulfill the usual requirements for light tiles for interior lighting, which lie between approximately 800 and 3,000 cd/m2, without problems. This is true even for an application in backlighting of LCD picture screens, where 5,000 to 15,000 cd/m2 are usually required, or for phototherapy applications. The luminous body according to the invention can be dimensioned substantially as desired, i.e. luminous surfaces of substantially any size whatsoever can be realized. The intensity differences among the individual light sources are averaged out by the good lateral light distribution. Given a regular arrangement of light sources of different colors, for example with red, green, blue, or white light, a very well controllable color mixing can also be achieved. If light sources with blue light are used, the light emission surface 4 may be provided with a color conversion phosphor which partly converts the blue light into light of longer wavelengths. Light sources of substantially any color can be realized in this manner without the phosphor used for color conversion having to be introduced into the light sources, in particular into the LEDs. Life and efficacy problems can thus be avoided, in particular in highly loaded LEDs. In addition, the color of the light can be changed through a simple exchange of the light emission surface 4. The spatial radiation characteristic of the luminous body is substantially defined by the shape and gradient of the light emission surface 4 and usually have a Lambert-type character. The light emission surface 4 may also be coated with optical foils which transmit light only within given angular regions and reflect it in other angular regions, so that a planar light source with a different radiation characteristic can be realized such as, for example, for certain applications (desk lighting). The light not transmitted is not lost but is reflected back into the luminous body. Finally, moving background lighting effects can be realized through a (sequential) switching on and off of individual groups or strips of LEDs, for example for use in LCD-TV displays.

20060807

20140701

20080619

69779.0

F21V1100

GRAMLING, SEAN P

Luminous Body

UNDISCOUNTED

ACCEPTED

F21V

ACCEPTED

Selective Growth Medium for Listeria Spp

Disclosed is a growth medium containing nitrofurantoin. The growth medium is selective for the growth of Listeria spp.

1. A selective growth medium specific for Listeria spp. comprising, in combination, lithium chloride and one or more antibiotics or salts thereof, in concentrations effective to selectively inhibit non-Listeria organisms while enhancing growth of Listeria spp. 2. The medium of claim 1, wherein the antibiotics are selected from the group consisting of ceftazimide, phosphomycin, polymyxin, and nitrofurantoin. 3. The medium of claim 1, being substantially devoid of acriflavin. 4. The medium of claim 1, further comprising esculin. 5. The medium of claim 1, wherein the lithium chloride is present in a concentration of from about 1 g/L to about 10 g/L. 6. The medium of claim 5, wherein the lithium chloride is present in a concentration of from about 5 g/L. 7. The medium of claim 2, wherein the nitrofurantoin is present in a concentration of from about 0.001 g/L to about 0.01 g/L. 8. The medium of claim 7, wherein the nitrofurantoin is present in a concentration of about 0.006 g/L. 9. A selective and differential medium for Listena spp. comprising an agar base layer substantially devoid of, acriflavin, the base layer containg lithium chloride, a growth enhancer of Listeria spp., and antibiotics or salts thereof in concentrations effective to selectively inhibit non-Listeria organisms. 10. The medium of claim 9, wherein the growth enhancer comprises an iron-contaning compound. 11. The medium of claim 10, wherein the growth enhancer is ferric ammonium citrate. 12. The medium of claim 9, wherein the antibiotics are selected from the group consisting of ceftazimide, phosphomycin, polymyxin, and nitrofurantoin. 13. The medium of claim 12, wherein the polymyxin is polymyxin E. 14. A Listeria spp.-selective medium comprising, in combination, tryptone, peptone, sodium chloride, dibasic potassium phosphate, yeast extract, cyclohexamide, naladixic acid, ferric ammonium citrate, and esculin, in concentrations effective to promote growth of Listeria spp. 15. The medium of claim 14, further comprising, in combination, ceftazimide, phosphomycin, polymyxin E, lithium chloride, and nitrofurantoin in concentrations effective to inhibit growth of non-Listetia organisms. 16. The medium of claim 14, the medium being substantially devoid of acriflavin. 17. The medium of claim 14, wherein the tryptone concentration is about 17.0 g/L. 18. The medium of claim 14, wherein the peptone concentration is about 3.0 g/L. 19. The medium of claim 14, wherein the sodium chloride concentration is about 5.0 g/L. 20. The medium of claim 14, wherein the dibasic potassium phosphate concentration is about 6.0 g/L. 21. The medium of claim 14, wherein the yeast extract concentration is about 6.0 g/L. 22. The medium of claim 14, wherein the cyclohexamide concentration is about 0.05 g/L. 23. The medium of claim 14, wherein the naladixic acid concentration is about 0.04 g/L. 24. The medium of claim 14, wherein the esculin concentration is about 1.0 g/L. 25. The medium of claim 15, wherein the ceftazimide concentration is about 0.04 g/L. 26. The medium of claim, wherein the phosphomycin concentration is about 0.04 g/L. 27. The medium of claim 15, wherein the polymyxin E concentration is about 0.01 g/L. 28. The medium of claim 14, wherein the ferric ammonium citrate concentration is about 0.5 g/L. 29. The medium of claim 15, wherein the lithium chloride concentration is about 5.0 g/L. 30. The medium of claim 15, wherein the nitrofurantoin concentration is about 0.006 g/L. 31. A Listeria spp.-selective medium comprising, in combination, a. tryptone, in a concentration of about 17.0 g/L; b. peptone, in a concentration of about 3.0 g/L; c . sodium chloride, in a concentration of about 5.0 g/L, d. anhydrous dibasic potassium phosphate, in a concentration of about 6.0 g/L; e. yeast extract, in a concentration of about 6.0 g/L; f. cyclohexamide, in a concentration of about 0.05 g/L; g. naladixic acid, in a concentration of about 0.04 g/L; h. esculin, in a concentration of about 1.0 g/L; i. ceftazimide, in a concentration of about 0.04 g/L; j. phosphomycin, in a concentration of about 0.04 g/L; k. polymyxin E, in a concentration of about 0.01 g/L; l. ferric ammonium citrate, in a concentration of about 0.5 g/L; m. lithium chloride, in a concentration of about 5.0 g/L; and n. nitrofurantoin, in a concentration of about 0.006 g/L.

CROSS-REFERENCE TO RELATED APPLICATION This application claims priority under 35 USC §119(e) to U.S. Provisional Application Ser. No. 60/543,947, filed 12 Feb. 2004, the entirety of which is incorporated herein. REFERENCES AND INCORPORATION BY REFERENCE Complete bibliographic citations for the references cited herein are contained in a section titled “REFERENCES,” immediately preceding the claims. All of the documents listed in the “REFERENCES” section are incorporated herein. FIELD OF THE INVENTION The invention is directed to a Listeria-selective growth medium. The preferred embodiment of the medium comprises nitrofurantoin, esculin and lithium chloride, and is substantially devoid of acriflavin. BACKGROUND OF THE INVENTION Considerable microbiological research has been devoted to understanding the nutritional requirements and environmental conditions that promote selective growth of Listeria spp. Dependable selective culturing of Listeria spp. is becoming increasingly important in the food industry because of evolving federal and state regulations requiring more frequent monitoring of food-processing equipment and environments. Listeria spp. is considered to be a critical indicator of the effectiveness of industrial sanitation practices for two principle reasons: 1) organisms of the genus Listeria are ubiquitous; and 2) the species Listeria monocytogenes is pathogenic and thus a cause of concern for public health officials. Among the bacteria of the genus Listeria spp., only the species monocytogenes is known to be pathogenic to humans. Other species of Listeria such as L. ivanovii are not generally pathogenic or are pathogenic only for animals. L. monocytogenes is a gram-positive, motile, aerobic and facultatively anaerobic bacterium which is ubiquitous in nature. It can cause various diseases in man including meningoencephalitis, low-grade septicemia, infectious mononucleosis-like syndrome, pneumonia, endocarditis, bacterial aortic aneurysm, localized abscesses, papular or pustular cutaneous lesions, conjunctivitis and urethritis. In the past decade, L. monocytogenes has been recognized as a major food-borne pathogen. Outbreaks of listeriosis have been linked to a number of contaminated foods such as coleslaw, Mexican-style soft cheese, pasteurized millk and turkey franks. It has been isolated from fresh produce, dairy products, processed meats and seafood products. About 500 people die each year in the United States from Listerial food poisoning; the victims are usually the immunocompromised, pregnant women and neonates. The isolation and the identification of the bacterium L. monocytogenes is a major problem in the monitoring of food hygiene and of medical bacteriology. While a number of putative media for selective culture of Listeria spp. have been described in the literature, each have disadvantages. For example, Lovett et al. describe an enrichment broth for selective isolation of Listeria spp. and U.S. Pat. No. 6,228,606 describes a method for inhibiting L. monocytogenes using a synthetic chromogenic substrate. However, these media detect every species of the genus Listeria spp. Thus, supplementary identification tests, such as microscopic, biochemical, immunological, and/or genetic tests must be used to establish the presence of the pathogenic monocytogenes species. However, these supplementary manipulations increase the length of time and cost of the analyses, require a vast number of reagents and the use of qualified personnel, and are often a source of error or at least the cause of lower precision and reliability. This is especially true when there is a very small amount of L. monocytogenes present. Other methods for the selective culture of Listeria spp. have been described, such as Fraser and Sprerber's medium exploiting the high salt tolerance of Listeria spp., and its ability to hydrolyze esculin. Esculin is a glucoside (6-(beta-D-glucopyranosyloxy)-7-hydroxy-2H-1-benzopyran-2-one, CAS No. 531-75-9) obtained from Aesculus hippocastanum (the horsechestnut) and is characterized by its fine blue fluorescent solutions. In this approach, the beta-glucosidase activity of Listeria hydrolyzes esculin. The hydrolysis products, in combination with iron salts present in the medium, yield a black pigment that is used as a colorimetric indicator of a positive sample. Donnelly & Baigent developed a modified medium similar to the Fraser & Sprerber broth but lacking the colorimetric indicator. This medium exploits the salt tolerance of Listeria spp. in conjunction with several antibiotics to yield a medium selective for the growth of Listeria. However, these media slow the overall growth rate of Listeria cells to achieve inhibition of competitive micro-flora in the sample being tested. Further, the combination of high salt concentration and antibiotics prevents the growth of certain strains of Listeria, most notably L. ivanovii and L. grayi. Another complicating aspect of conventional selective media is the presence of acriflavin. Acriflavin is an acridine dye that is an effective inhibitor of competitive gram-positive bacteria such as Bacillus spp. Unfortunately, acriflavin not only is a suspected carcinogen but is also a fluorophore that is incorporated into the DNA and proteins of growing cells. Thus, acriflavin causes unwanted fluorescent interference in many fluorescence-based assays, such as enzyme-linked immunosorbent assays (ELISA) and the polymerase chain reaction (PCR). Many commercially available Listeria detection products rely upon the use of fluorescent reagents for analyte detection. Thus, there remains a long-felt and unmet need for a Listeria-selective medium that 1) does not appreciably interfere with the growth rate of Listeria spp.; 2) does not yield bacterial biomass contaminated with interfering fluorophores; and 3) strongly inhibits the growth of non-Listeria organisms. SUMMARY OF THE INVENTION The present invention is a culture medium for investigating, isolating, counting and directly identifying pathogenic bacteria of the genus Listeria. The medium promotes the growth of Listeria spp. while simultaneously inhibiting the growth of non-Listeria organisms. Further, the medium does not produce a bacterial biomass contaminated with interfering fluorophores. The medium or the present invention comprises nitrofurantoin, esculin and lithium chloride and is substantially devoid of acriflavin. In a preferred embodiment, no acriflavin is present. In an alternative embodiment, acriflavin is present in concentrations of about 0.01 g/L or less. The medium also uses much lower concentrations of lithium chloride than the prior art. In a preferred embodiment, lithium chloride is present in concentrations of about 5 g/L or less. The rapid and accurate identification of Listeria spp is just one of the advantages the medium of the present invention. For instance, the medium of the present invention does not require a secondary transfer to another medium. Further, the medium does not fluoresce, and therefore is compatible with ELISA-and PCR-based tests to identify Listeria spp. Further still, procedures using the medium of the present invention require no special enrichment procedures or secondary manipulations. Finally, the medium of the present invention can be used to detect L. monocytogenes in a host of foods, food products and environmental samples, even in the presence of large populations of other non-Listeria organisms. The complete scope of the invention will appear more fully from the following detailed description of the preferred embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION The selective medium of the present invention promotes and enhances the growth of Listeria spp. while simultaneously inhibiting the growth of non-Listeria organisms. The medium may be used with any type of food product or environmental sample. In a preferred embodiment (see PDX-1 in Table 1), the medium comprises tryptone, in a concentration ranging from about 15 to about 25 g/L, with a preferred concentration of about 16 to about 18 g/L, with a further preferred concentration of about 17 g/L; peptone, in a concentration ranging from about 1 to about 5 g/L, with a preferred concentration of about 2 to about 4 g/L, with a further preferred concentration of about 3 g/L; sodium chloride, in a concentration ranging from about 1 to about 10 g/L, with a preferred concentration of about 2.5 to about 7.5 g/L, with a further preferred concentration of about 5 g/L; anhydrous dibasic potassium phosphate, in a concentration ranging from about 1 to about 10 g/L, with a preferred concentration of about 2.5 to about 7.5 g/L, with a further preferred concentration of about 5 g/L; yeast extract, in a concentration ranging from about 1 to about 10 g/L, with a preferred concentration of about 2.5 to about 7.5 g/L, with a further preferred concentration of about 6 g/L; cyclohexamide, in a concentration ranging from about 0.01 to 0.1 g/L, with a preferred concentration of about 0.025 to about 0.075 g/L, with a further preferred concentration of about 0.05 g/L; acriflavin, in a concentration ranging from no more than about 0.01; naladixic acid, in a concentration ranging from about 0.01 to about 0.1 g/L, with a preferred concentration of about 0.025 to about 0.075 g/L, with a further preferred concentration of about 0.04 g/L; and esculin, in a concentration ranging from about 0.5 to 5 g/L, with a preferred concentration of about 0.75 to about 2 g/L, with a further preferred concentration of about 1 g/L. In an especially preferred embodiment (see PDX-2 in Table 1), the selective medium of the present invention comprises tryptone, peptone, sodium chloride, anhydrous dibasic potassium phosphate, yeast extract, cyclohexamide, naladixic acid and esculin in the amounts described above but contains no acriflavin. Acriflavin consistently inhibits all of the Bacillus spp. but also inhibits the hemolytic activity of L. monocytogenes. The ingredients of the selective medium of the present invention are dissolved in distilled water and autoclaved at approximately 121 psig until sterile, usually about 15 min. After cooling, supplements are added. Preferred supplements include ceftazimide, phosphomyocin, polymyxin E, ferric ammonium citrate, lithium chloride and nitrofurantoin (Table 2). Ceftazimide, phosphomyocin, polymyxin E and nitrofurantoin are all antibiotics. Ceftazimide is a third generation cephalosporin, and acts to inhibit cell wall synthesis. Other cephalosporins such as ceftriaxone, moxolactam, cefotaxime, cefpodoxime, ceftizoxime, cefoperazone may also be used. The medium of the present invention preferably contains ceftazimide in a concentration ranging from about 0.04 g/L. Phosphomycin is an antibiotic principally excreted through the kidney. Several studies have shown its activity against gram-positive and gram-negative organisms (Kestle, Kwan), and its clinical efficiency in the treatment of infections of the respiratory (Bacardi), gastrointestinal (Taylor), and urinogenital (Allona) tracts. The medium of the present invention preferably contains phosphomycin in a concentration of about 0.04 g/L. Polymyxin E, also known as colistin, (CAS No. 1066-17-7) is frequently used as an oral drug for flora suppression of the gastrointestinal canal. The suppression effect is dose dependent because polymyxin E is moderately inactivated by faecal and food compounds. Polymyxin compounds are derived from various species of the soil bacterium Bacillus, and are active against gram-negative bacteria. Polymyxin E acts by disrupting the cell membranes of bacteria, destroying their ability to function as osmotic barriers. The medium of the present invention preferably contains polymyxin E in a concentration of about 0.01 g/L. Ferric ammonium citrate is an iron-containing salt that is often used in the treatment of some forms of anemia. The present medium uses ferric ammonium citrate as a growth enhancer for Listeria spp. A concentration ranging from about 0.1 to about 1.0 g/L of ferric ammonium citrate is used, with a preferred concentration ranging from about 0.025 g/L to about 0.075 g/L, and a further preferred concentration of 0.05 g/L. Lithium chloride is a salt commonly used in selective growth media because high salinity was believed necessary to control bacterial competitors of Listeria spp., such as Enterococcus spp. and Bacillus spp. However, the medium of the present invention uses much lower concentrations of lithium chloride than conventional media. Surprisingly, the low levels of salinity remain effective at inhibiting bacterial competitors. For instance, conventional media often contain lithium chloride in concentrations ranging as high as 10 g/L to 15 g/L. However, the medium of the present invention preferably contains a concentration of lithium chloride ranging from about 1 to about 10 g/L, with a preferred concentration ranging from about 2.5 to about 7.5 g/L, with a further preferred concentration of about 5 g/L or less. Nitrofurantoin is an antibiotic with signifiant anti-microbial activity against many potential gram-positive competitors. Nitrofurantoin has been shown to be effective at concentrations from about one to two orders of magnitude lower than the minimum inhibitory concentration for Listeria spp. (Soriano, Safdar). Further, because nitrofurantoin is non-fluorescent, the selective medium of the present invention does not interfere with ELISA-or PCR-based detection protocols. The medium of the present invention preferably contains a concentration of nitrofurantoin ranging from about 0.001 to about 0.01 g/L, with a preferred concentration of about 0.0025 to about 0.0075 g/L, with a further preferred concentration of about 0.006 g/L. The following Examples illustrate the features of the novel selective medium disclosed and claimed herein. The Examples are included solely to provide a more complete disclosure of the invention and do not limit the scope of the medium disclosed and claimed herein in any fashion. EXAMPLES Example 1 TABLE 1 Medium Formulation, Versions PDX-1 and PDX-2. Ingredient PDX-1 (g/L) PDX-2 (g/L) Tryptone 17.0 17.0 Peptone 3.0 3.0 Sodium Chloride 5.0 5.0 Dibasic Potassium Phosphate (anhydrous) 6.0 6.0 Yeast extract 6.0 6.0 Cyclohexamide 0.05 0.05 Acriflavin 0.01 — Naladixic acid 0.04 0.04 Esculin 1.0 1.0 The solid ingredients were dissolved in distilled water and autoclaved at 121 psig for 15 min to sterilize. After cooling, the following supplements were added: TABLE 2 Supplements. Supplement name PDX-1 PDX-2 Ceftazimide 0.04 g/L 0.04 g/L Phosphomycin 0.04 g/L 0.04 g/L Polymyxin E 0.01 g/L 0.01 g/L Ferric Ammonium Citrate 0.5 g/L 0.5 g/L Lithium Chloride* 5.0 g/L 5.0 g/L Nitrofurantoin** — 0.006 g/L *Lithium chloride is exothermic when dissolved in water. Appropriate care must be taken when adding it to the medium. **Nitrofurantoin is insoluble in water. A 10 mg/mL stock solution was made in sterile DMSO. The nitrofurantoin/DMSO stock solution was then added to the rest of the medium (600 microliters of stock solution/L medium yields 0.006 g/L nitrofurantoin in the final medium). # Solid-medium plates were made from the liquid medium by adding 15 g agar per liter of liquid medium, bringing the medium to a boil to dissolve the agar, cooling the solutions, and sterilizing the same. Example 2 Comparison of Growth Rates of: PDX-1 vs. Fraser Broth The purpose of this Example is to compare the growth rate of L. monocytogenes in Fraser broth versus the growth of L. monocytogenes in PDX-1 liquid medium. Cultures of L. monocytogenes (100 microliters of 10-7 dilution; 1/10 serial dilutions on peptone from overnight L. monocytogenes culture in tryptone soy broth (TSB)) were added to 3 mL of Fraser broth and 3 mL of PDX-1. Every hour starting at the time of inoculation, 100 microliters of both the PDX-1 medium and Fraser medium were plated on PALCAM plates in duplicate and incubated at 37 C for the enumeration of colonies. (For data on PALCAM plates, see Van Netten). PALCAM plates are available commercially from a number of international suppliers.) The growth rates of Listeria spp. on PDX-1 and Fraser broth media are shown in Table 3. TABLE 3 Growth Rates of PDX-1 compared to Fraser Broth (CFU/0.1 mL) Hour 0 1 2 3 4 5 PDX-1 65 73 69 72 131 273 67 72 76 100 149 257 Fraser 59 74 66 68 94 70 57 66 81 81 77 100 The data show that the Listeria spp. in the PDX-1 sample were able to recover from inoculation and start growth faster than the samples grown in Fraser broth. Also of interest is the fact that both sets of samples were inoculated from the same stock and had the same volume of inoculation. Thus the difference in initial cell counts between the two media (65 and 67 for PDX-1; 59 and 57, for Fraser broth) is significant, suggesting that the PDX-1 medium is less stressful to the cells at initial inoculation. In both runs, the Listeria displayed greater survivability in the PDX-1 medium as compared to the Fraser broth. Example 3 Growth of ATCC Cultures on Solid PDX-1, PDX-2, and Modified Oxford Broth The purpose of this Example was to plate out ATCC cultures of various bacteria, including Listeria spp., on solid PDX-1 and PDX-2 media to obtain a record of their respective colony morphologies, as well as to compare these morphologies to those of corresponding colonies grown on conventional media. A loop of overnight Trypticase Soy Broth (TSB) culture was streaked out on PDX-1, PDX-2, and Oxford broth supplemented with moxalactam. The various primary cultures were obtained from the American Type Culture Collection, Manassas, Virginia. Plates were stored at 37 C and checked at 20 and 40 hours. The results after 20 hours incubation are shown in Table 4. TABLE 4 Growth of Different Species on Various Solid media After 20 Hr Incubation at 37 C. Species PDX-1 PDX-2 Oxford + Mox S. choleraesuis − − − M. luteus − − − S. aureus − − Regular, round, off-white colonies L. welshimeri + + + L. ivanovii + + + L. grayi − − Area of some discoloration, without any noticeable colonies where the streak started L. seelgreri − − − L. monocytogenes + + + L. innocua + + + E. faecalis Discoloration without Discoloration without visible Discoloration without visible colonies at colonies at location of start of visible colonies at location of start of streak location of start of streak streak As can be seen from the data, the medium according to the present invention is highly selective for the growth of Listeria spp. and highly inhibitory of the growth of non-Listeria species. It is understood that the invention is not confined to the particular construction and arrangement of parts illustrated and described herein, but embraces such modified forms thereof as come within the scope of the following claims. REFERENCES Allona, A. et al. (1977) “Fosfomycin in chronic urinary infections,” Chemotherapy (Basel) 23(Suppl. 1):267-274. Al-Zoreky, N. et al, (1990) “Highly Selective Medium for Isolation of Listeria monocytogenes from Food” Appl. Environ. Microbiol. October:3154-3157. Bacardi, R. et al. (1977) “Treatment of respiratory infections with fosfomycin,” Chemotherapthy 23(Suppl. 1) :343-347. Bannerman, E. et al. (1998) “A New Selective Medium for Isolating Listeria spp. from Heavily Contaminated Material, ”Appl. Environ. Microbiol. 165-167. Blanco, M. et al. (1989) “A Technique for the Direct Identification of Haemolytic-pathogenic Listeria on Selective Plating Media,” Letters in Appl. Microbiol. 125-128. Cassiday, P. et al. (1989) “Evaluation of Ten Selective Direct Plating Media for Enumeration of L. monocytogenes in Hams and Oysters, ” Food Microbiol. 113-125. Donnelly, C. & G. Baigent (1986) “Method for flow cytometric detection of Listeria monocytogenes in milk,” Appl. Environ. Microbiol. 52:689-695. Fraser, J and W. Sprerber (1988) “Rapid detection of Listeria in food and environmental samples by Esculin hydrolysis,” J. Food Prot. 51:726-765. Kestle, D. and W. Kirby (1970) “Clinical pharmacology and in vitro activity of phosphonomycin,” Antimicrob. Agents Chemother. 332-337. Kwan, K. et al. (1971) “Pharmacokinetics of fosphomycin in man” I. Intravenous administration,” J. Pharm. Sci. 60:678-684. Lovett, J. D. et al. (1987) “Listeria monocytogenes in raw milk: detection, incidence, and pathogenicity,” J. Food Prot. 50:188-192. Peterson, M. et al. (1993) “Parameters for Control of Listeria monocytogenesin Smoked Fishery Products . . . ,” J. Food Prot. 56:11:938-943. Safdar, A. & D. Armstrong (2003) “Antimicrobial activities against 84 Listeria monocytogenes isolates from patients with systemic Listeriosis at a comprehensive cancer center (1955-1997),” J. Clin. Microbiol. 41:483-485. Soriano, F. et al. (1995) “Antimicrobial susceptibilities of Corynebacteriun species and other non-spore forming gram-positive bacilli to 18 antimicrobial agents,” Antimicrob. Agents Chemother. 39:208-214. Taylor, C. et al. (1977) “Enteropathogenic E. coli gastroenterocolitis in neonates treated with fosfomycin,” Chemotherapy (Basel) 23(Suppl. 1):310-5314. Van Netten, P. et al. (1989) “Liquid and Solid Selective Differential Media for the Detection and Enumeration of L. monocytogenes and other Listeria spp., ” Int. J. of Food Microbiol. 1215-1217.

<SOH> BACKGROUND OF THE INVENTION <EOH>Considerable microbiological research has been devoted to understanding the nutritional requirements and environmental conditions that promote selective growth of Listeria spp. Dependable selective culturing of Listeria spp. is becoming increasingly important in the food industry because of evolving federal and state regulations requiring more frequent monitoring of food-processing equipment and environments. Listeria spp. is considered to be a critical indicator of the effectiveness of industrial sanitation practices for two principle reasons: 1) organisms of the genus Listeria are ubiquitous; and 2) the species Listeria monocytogenes is pathogenic and thus a cause of concern for public health officials. Among the bacteria of the genus Listeria spp., only the species monocytogenes is known to be pathogenic to humans. Other species of Listeria such as L. ivanovii are not generally pathogenic or are pathogenic only for animals. L. monocytogenes is a gram-positive, motile, aerobic and facultatively anaerobic bacterium which is ubiquitous in nature. It can cause various diseases in man including meningoencephalitis, low-grade septicemia, infectious mononucleosis-like syndrome, pneumonia, endocarditis, bacterial aortic aneurysm, localized abscesses, papular or pustular cutaneous lesions, conjunctivitis and urethritis. In the past decade, L. monocytogenes has been recognized as a major food-borne pathogen. Outbreaks of listeriosis have been linked to a number of contaminated foods such as coleslaw, Mexican-style soft cheese, pasteurized millk and turkey franks. It has been isolated from fresh produce, dairy products, processed meats and seafood products. About 500 people die each year in the United States from Listerial food poisoning; the victims are usually the immunocompromised, pregnant women and neonates. The isolation and the identification of the bacterium L. monocytogenes is a major problem in the monitoring of food hygiene and of medical bacteriology. While a number of putative media for selective culture of Listeria spp. have been described in the literature, each have disadvantages. For example, Lovett et al. describe an enrichment broth for selective isolation of Listeria spp. and U.S. Pat. No. 6,228,606 describes a method for inhibiting L. monocytogenes using a synthetic chromogenic substrate. However, these media detect every species of the genus Listeria spp. Thus, supplementary identification tests, such as microscopic, biochemical, immunological, and/or genetic tests must be used to establish the presence of the pathogenic monocytogenes species. However, these supplementary manipulations increase the length of time and cost of the analyses, require a vast number of reagents and the use of qualified personnel, and are often a source of error or at least the cause of lower precision and reliability. This is especially true when there is a very small amount of L. monocytogenes present. Other methods for the selective culture of Listeria spp. have been described, such as Fraser and Sprerber's medium exploiting the high salt tolerance of Listeria spp., and its ability to hydrolyze esculin. Esculin is a glucoside (6-(beta-D-glucopyranosyloxy)-7-hydroxy-2H-1-benzopyran-2-one, CAS No. 531-75-9) obtained from Aesculus hippocastanum (the horsechestnut) and is characterized by its fine blue fluorescent solutions. In this approach, the beta-glucosidase activity of Listeria hydrolyzes esculin. The hydrolysis products, in combination with iron salts present in the medium, yield a black pigment that is used as a colorimetric indicator of a positive sample. Donnelly & Baigent developed a modified medium similar to the Fraser & Sprerber broth but lacking the colorimetric indicator. This medium exploits the salt tolerance of Listeria spp. in conjunction with several antibiotics to yield a medium selective for the growth of Listeria. However, these media slow the overall growth rate of Listeria cells to achieve inhibition of competitive micro-flora in the sample being tested. Further, the combination of high salt concentration and antibiotics prevents the growth of certain strains of Listeria, most notably L. ivanovii and L. grayi. Another complicating aspect of conventional selective media is the presence of acriflavin. Acriflavin is an acridine dye that is an effective inhibitor of competitive gram-positive bacteria such as Bacillus spp. Unfortunately, acriflavin not only is a suspected carcinogen but is also a fluorophore that is incorporated into the DNA and proteins of growing cells. Thus, acriflavin causes unwanted fluorescent interference in many fluorescence-based assays, such as enzyme-linked immunosorbent assays (ELISA) and the polymerase chain reaction (PCR). Many commercially available Listeria detection products rely upon the use of fluorescent reagents for analyte detection. Thus, there remains a long-felt and unmet need for a Listeria -selective medium that 1) does not appreciably interfere with the growth rate of Listeria spp.; 2) does not yield bacterial biomass contaminated with interfering fluorophores; and 3) strongly inhibits the growth of non- Listeria organisms.

<SOH> SUMMARY OF THE INVENTION <EOH>The present invention is a culture medium for investigating, isolating, counting and directly identifying pathogenic bacteria of the genus Listeria. The medium promotes the growth of Listeria spp. while simultaneously inhibiting the growth of non- Listeria organisms. Further, the medium does not produce a bacterial biomass contaminated with interfering fluorophores. The medium or the present invention comprises nitrofurantoin, esculin and lithium chloride and is substantially devoid of acriflavin. In a preferred embodiment, no acriflavin is present. In an alternative embodiment, acriflavin is present in concentrations of about 0.01 g/L or less. The medium also uses much lower concentrations of lithium chloride than the prior art. In a preferred embodiment, lithium chloride is present in concentrations of about 5 g/L or less. The rapid and accurate identification of Listeria spp is just one of the advantages the medium of the present invention. For instance, the medium of the present invention does not require a secondary transfer to another medium. Further, the medium does not fluoresce, and therefore is compatible with ELISA-and PCR-based tests to identify Listeria spp. Further still, procedures using the medium of the present invention require no special enrichment procedures or secondary manipulations. Finally, the medium of the present invention can be used to detect L. monocytogenes in a host of foods, food products and environmental samples, even in the presence of large populations of other non- Listeria organisms. The complete scope of the invention will appear more fully from the following detailed description of the preferred embodiment of the invention. detailed-description description="Detailed Description" end="lead"?

20070725

20110614

20080124

59515.0

C12N120

MARX, IRENE

SELECTIVE GROWTH MEDIUM FOR LISTERIA SPP

SMALL

ACCEPTED

C12N

ACCEPTED

Injection Device for Administering a Vaccine

A manually-powered injection device that self-administers a painless injection. The injection device provides a method for substantially painless injections of vaccine and other medication into a patient that does not require the use of an anesthetic, that does not require the medical personnel to spend a substantial amount of time performing the injection procedure, that is relatively simple and inexpensive to perform and operate, and that provides a relatively high degree of safety for both the medical personnel and for the patient. The injection needle can have an outside diameter greater than 0.10 mm and less than about 0.38 mm. The vaccine or other medicament can be injected painlessly through the needle and into the patient at a substantially constant volumetric flow rate of about 0.05 μL/s to about 50 μL/s, typically over a 3- to 5-minute period of time. The injection device is configured for easy handling, and is manually powered by the use of the hand or fingers of the medical technician, patient or other person.

1. A manually-powered injection device for painless inter-muscular injection of an injectable liquid composition from with a reservoir, comprising: a) a housing having a base for semi-permanent attachment to the skin of a patient, b) an injection needle disposed substantially perpendicular to the base and within the housing, the needle having an injection end, and configured for axial movement manually between a first position wherein the injection end is within the housing and a second position wherein the injection end extends outwardly from the base to a distance sufficient for intramuscular insertion thereof, the injection needle having an outside diameter greater than 0.10 mm and less than about 0.38 mm, c) a means for retaining a reservoir containing an injectable liquid composition, d) a means for providing liquid communication between the retained reservoir and the injection needle, and e) a means for injecting the injectable liquid composition from the retained reservoir through the needle. 2. The injection device of claim 1 wherein the means for injecting is a manually-powered spring that is configured to exert pressure upon the injectable liquid composition within the retained reservoir. 3. The injection device of claim 1, further comprising a needle insertion securement configured to retain the inserted needle in its second position while injecting the liquid composition. 4. The injection device of claim 3 further comprising a means for retracting the injection needle, whereby the injection end of the needle can be retracted from its second position to a third position wherein the injection end of the needle is within the housing. 5. The injection device of claim 3 further comprising a needle carriage to which the injection needle is affixed, the needle carriage being configured for axial movement between a first position associated with the first position of the injection needle, and a second position associated with the second position of the injection needle, in response to a manual force applied by a person. 6. The injection device according to claim 5 further comprising an implement for use in applying the manual force to the needle carriage. 7. The injection device according to claim 5 wherein the needle insertion securement is configured to retain the needle carriage in its second position. 8. The injection device according to claim 7, further comprising a retracting means comprising a disengagement means configured to disengage the needle insertion securement from the needle carriage, and a power means configured to bias the needle carriage to a third position that is associated with a third position of the injection needle wherein the injection end of the needle is within the housing. 9. The injection device according to claim 1 wherein the device further comprises a separable base, a base securement means configured for separable securement of the separable base to the housing, and a base separation means configured for separation of the separable base from the housing, wherein the separable base comprising an adhesive for attachment thereof to the skin of the patient. 10. A manually-powered injection device for painless inter-muscular injection of an injectable liquid composition, comprising: a) a housing having a base for semi-permanent attachment to the skin of a patient, b) an injection needle disposed substantially perpendicular to the base and within the housing, the needle having an injection end, and configured for axial movement manually between a first position wherein the injection end is within the housing and a second position wherein the injection end extends outwardly from the base to a distance sufficient for intramuscular insertion thereof, the injection needle having an outside diameter greater than 0.10 mm and less than about 0.38 mm, c) a reservoir containing an injectable liquid composition, d) a means for liquid communication between the reservoir and the injection needle, and e) a means for injecting the liquid composition from the reservoir to the injection end of the needle. 11. The injection device of claim 10 wherein the means for injecting is a manually-powered spring that is configured to exert pressure upon the injectable liquid composition within the retained reservoir. 12. The injection device of claim 10, further comprising a needle insertion securement configured to retain the inserted needle in its second position while injecting the liquid composition. 13. The injection device of claim 12 further comprising a means for retracting the injection needle, whereby the injection end of the needle can be retracted from its second position to a third position wherein the injection end of the needle is within the housing. 14. The injection device of claim 12 further comprising a needle carriage to which the injection needle is affixed, the needle carriage being configured for axial movement between a first position associated with the first position of the injection needle, and a second position associated with the second position of the injection needle, in response to a manual force applied by a person. 15. The injection device according to claim 14 further comprising an implement for use in applying the manual force to the needle carriage. 16. The injection device according to claim 14 wherein the needle insertion securement is configured to retain the needle carriage in its second position. 17. The injection device according to claim 16, further comprising a retracting means comprising a disengagement means configured to disengage the needle insertion securement from the needle carriage, and a power means configured to bias the needle carriage to a third position that is associated with a third position of the injection needle wherein the injection end of the needle is within the housing. 18. The injection device according to claim 14 wherein the needle carriage comprises threads, and the reservoir comprises cooperating threads that can engage and retain the threads of the reservoir. 19. The injection device according to claim 18 wherein the reservoir comprises a penetrable membrane, wherein when the cooperating threads of the reservoir and the needle carriage are engaged, a piercing conduit in liquid communication with the injection needle can penetrate the penetrable membrane to establish liquid communication between the reservoir and the injection needle. 20. The injection device according to claim 10 wherein the device further comprises a separable base, a base securement means configured for separable securement of the separable base to the housing, and a base separation means configured for separation of the separable base from the housing, wherein the separable base comprising an adhesive for attachment thereof to the skin of the patient.

BACKGROUND OF THE INVENTION The present invention relates to the injection of vaccines and other medication and, more particularly, to an injection device that can be used in a method for administering vaccine injections painlessly for a patient. Conventional medical injection devices for injecting medication into the muscle or tissue of a patient typically comprise some form of a manual hypodermic syringe. Generally speaking, a hypodermic syringe consists of a cylindrical barrel having a chamber that provides a reservoir for a liquid medication, a distal end adapted to be connected to a hollow hypodermic needle and for placing one end of the needle into flow communication with the medication contained within the chamber, and a proximal end adapted for receiving a stopper and plunger assembly. The stopper and plunger assembly includes a stopper effective for moving along the barrel chamber and an elongated plunger effective for causing movement of the stopper. The needle of the hypodermic syringe is manually inserted into the patient through the skin. The stopper is moved along the barrel chamber by applying axial force to the plunger, thereby forcing the liquid medication out of the barrel chamber, through the hypodermic needle and into the muscle or tissue of the patient. Receiving an injection by such a conventional device can be a very traumatic experience, particularly for a child. The child's fears, and that of the child's parent, can become a significant medical problem if it leads to the child not receiving a required vaccination. These fears are predominately caused by pain that is associated with injections given by conventional injection devices and methods. We have found that the pain associated with an injection is related to the size of the needle and the flow rate at which the medication is injected. It has been found that the amount of pain or discomfort experienced by a patient increases as the outside diameter of the needle increases. It is believed that high flow rates of medication injection (e.g., about 0.5-2 ml per second) into the patient can tear internal tissue and cause pain. The tearing of tissue is caused by the build-up of excessive pressure within the tissue when the surrounding tissue is unable to quickly absorb the injected medication. While the injection of a medication at a relatively slow flow rate is more comfortable for the patient, the increased amount of time the syringe remains in the hand of the medical personnel can make the technique tiring for such personnel as well as the patient. In addition, small vibrations or disturbances of the needle caused by movement of the medical personnel or the patient can result in pain to the patient. It is known that the fluctuation of flow rate of the injection of medication being delivered by a hand-held syringe can vary greatly. It is extremely difficult, if not impossible, to deliver a steady, very slow flow of medication from a hand-operated syringe (the human thumb depressing the syringe plunger) over an extended amount of time. It has also been found that the sight of the hypodermic needle by itself is often enough to cause many patients to become anxious and tense. This reaction in turn may cause the patient's muscles to become tight and hard, making needle penetration even more difficult and painful. A number of methods and devices have been developed for reducing or eliminating the pain and discomfort associated with medical injections. One such method includes the application of a topical anesthetic to the injection site on the patient's skin prior to the injection, which itself can be painful. While this method has reduced some of the discomfort associated with injections, the topical anesthetic does not substantially penetrate the skin into the deeper skin and muscle tissue, and can take significant time (up to 45 minutes) to show effects. Substantial pain and discomfort with intramuscular injections can remain. Another technique for reducing the pain and discomfort associated with medical injections includes the step of injecting an anesthetic at the site of the injection using a fine gauge needle, then inserting the larger medication hypodermic needle through the anesthetized skin to inject the medication at a constant and slow flow rate intramuscularly at the desired depth. Unfortunately, injecting an anesthetic into a patient can be painful, and is not always desirable, and the technique is relatively expensive and impractical for many routine injection procedures. In addition to reducing pain or discomfort to the patient, safety has also become a principal concern to medical personnel. Special precautions must be taken to avoid accidental needle sticks that could place a user at serious risk because of the danger from fluid borne pathogens. Despite the taking of special precautions, there still remains the possibility of an accidental needle contact and attendant injury. Accordingly, medical injection devices should operate to minimize the possibility of injury caused by accidental needle sticks. In recent years, increased emphasis has been placed on establishing treatment protocols aimed at providing a patient as well as medical personnel with greater freedom of movement. To this end, there is a great deal of interest in the development of light weight and easy-to-use portable injection devices. Accordingly, a need exists for substantially painless method and an apparatus for performing the method of injecting medication into a patient that does not require the use of an anesthetic, that does not require the medical personnel to spend a substantial amount of time performing a particular procedure, that is relatively simple, portable and inexpensive to perform and operate, that permits the patient a relatively high degree of movement during the injection, and that provides a relatively high degree of safety for both the medical personnel and for the patient. SUMMARY OF THE INVENTION The present invention relates to an injection device that is manually-powered and configured for self-administering painlessly an injectable liquid composition, such as a vaccine or medicament. The device can be used in a method for providing a substantially painless injection of the injectable liquid composition to a patient that does not require the use of an anesthetic, that does not require the medical personnel to spend a substantial amount of time performing the injection procedure, that is relatively simple and inexpensive to prepare and operate, and that provides a relatively high degree of safety for both the medical personnel and for the patient. The present invention further relates to a manually-powered injection device for self-administering painlessly an inter-muscular injection of an injectable liquid composition contained within a reservoir, comprising a) a housing having a base for semi-permanent attachment to the skin of a patient, b) an injection needle disposed substantially perpendicular to the base and within the housing, the needle having an injection end, and configured for axial movement manually between a first position wherein the injection end is within the housing and a second position wherein the injection end extends outwardly from the base to a distance sufficient for intramuscular insertion thereof, the injection needle having an outside diameter greater than 0.10 mm and less than about 0.38 mm, c) a means for retaining a reservoir for containing an injectable liquid composition, d) a means for providing liquid communication between the retained reservoir and the injection needle, e) a means for injecting the injectable liquid composition from the retained reservoir through the needle. The present invention also relates to a manually-powered injection device for self-administering painlessly an inter-muscular injection of an injectable liquid composition, comprising a) a housing having a base for semi-permanent attachment to the skin of a patient, b) an injection needle disposed substantially perpendicular to the base and within the housing, the needle having an injection end, and configured for axial movement manually between a first position wherein the injection end is within the housing and a second position wherein the injection end extends outwardly from the base to a distance sufficient for intramuscular insertion thereof, the injection needle having an outside diameter greater than 0.10 mm and less than about 0.38 mm, c) a reservoir for containing the injectable liquid composition, d) a means for liquid communication between the reservoir and the injection needle, and e) a means for injecting the injectable liquid composition from the reservoir to the needle. The present invention also provides an improved cartridge for use in a self-administering injection device, that comprises separate and spaced-apart filling and dispensing ports, and which allows a dispensing plunger to ascend within the cartridge during the injection in a direction toward the filling port. This can provide a visual signal when the distal end of the plunger approaches the filling end of the cartridge, at the completion of the liquid composition injection. In typical embodiments of the present invention, the needle is affixed to a needle carriage that is configured for axial movement between a first position associated with the first position of the injection needle, and a second position associated with the second position of the injection needle, in response to the manual force applied by the person. Upon manual insertion of the needle, a needle insertion securement secures the carriage in the second position the liquid composition is injected. The device is typically employs a manually-powered spring that is compressed during the manual needle insertion, which exerts pressure upon the injectable liquid composition within the retained reservoir. The needle carriage and the reservoir comprise cooperating threads that can engage and retain the reservoir within the carriage, and which can cause penetration of a penetrable membrane in the reservoir by the inlet end of the injection needle to establish liquid communication there between. At the end of the injection cycle, a needle retracting means can be activated, typically manually, to retract the injection needle, whereby the injection end of the needle is retracted from its second position in the body to a third position wherein the injection end of the needle is within the housing. The needle retracting means can employ a disengagement means configured to disengage the needle insertion securement from the needle carriage, and a power means configured to bias the needle carriage to the third position. An implement, such as a plunger or stem, can be used in place of the finger or hand to apply the manual insertion force to the needle carriage. The device can also comprises a separable base, a base securement means configured for separable securement of the separable base to the housing, and a base separation means configured for separation of the separable base from the housing, wherein the separable base comprising an adhesive for attachment thereof to the skin of the patient. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a cross-sectioned elevation view of a housing of a manually-powered painless injection device of the present invention in an extracted position, taken through line 1-1 of the housing shown in FIG. 4. FIG. 2 shows the cross-sectioned elevation view of FIG. 1 of the housing in an inserted position. FIG. 3 shows a cross-sectioned elevation view of the housing shown in FIG. 4, taken through line 3-3 of FIG. 4. FIG. 3A shows a detailed cross-sectional view of the housing of FIG. 3. FIG. 4 shows a top plan view of the housing of the manually-powered painless injection device. FIG. 5 shows a cross-sectioned elevation view of the housing of FIG. 4, taken through line 5-5. FIG. 6 shows a cross-sectioned elevation view of the housing of FIG. 4 taken through line 6-6. FIG. 7 shows a cross-sectioned plan view of the housing of FIG. 1, taken through line 7-7. FIG. 8 shows a cross-sectioned plan view of the housing of FIG. 1, taken through line 8-8. FIG. 9 shows an exploded cross-sectioned elevation view of the elements of the housing of FIG. 1. FIG. 10 shows a cross-sectioned elevation view of a syringe cartridge of a manually-powered painless injection device of the present invention in an extended position, taken through line 10-10 of the syringe cartridge shown in FIG. 12. FIG. 11 shows a cross-sectioned elevation view of the syringe cartridge in an extended position, taken through line 11-11 of FIG. 12. FIG. 12 shows a plan view of the syringe cartridge of FIG. 10. FIG. 13 shows a detailed cross-sectional elevation view of the syringe cartridge of FIG. 10. FIG. 14 shows another detailed cross-sectional elevation view of the syringe cartridge of FIG. 10. FIG. 15 shows a plan view of the syringe cartridge shown in FIG. 14. FIG. 16 shows a cross-sectioned plan view of the syringe cartridge of FIG. 11. FIG. 17 shows a bottom plan view of the syringe cartridge of FIG. 11. FIG. 18 shows an exploded cross-sectioned elevation view of the elements of the syringe cartridge of FIG. 10. FIG. 19 shows a cross-sectioned elevation view of the syringe cartridge of FIG. 10 containing an injectable liquid composition in a pressurized position. FIG. 20 shows a cross-sectioned elevation view of the housing and a separable base assembly prior to its attachment to the housing, and of a syringe cartridge prior to its installation into the housing. FIG. 21 shows the housing and syringe cartridge of FIG. 20, with the housing being affixed to a patient's skin. FIG. 22 shows the syringe cartridge being installed into the housing of FIG. 21. FIG. 23 shows the syringe cartridge being force into an inserted position within the housing. FIG. 24 shows the syringe cartridge in the inserted position within the housing, injecting the liquid composition. FIG. 25 shows the syringe cartridge in the inserted position within the housing, at the completion of the liquid composition injection. FIG. 26 shows the syringe cartridge in the inserted position within the housing of FIG. 25, being manipulated to retract the needle. FIG. 27 shows the syringe cartridge and housing of FIG. 26, with the needle retracted. FIG. 28 shows the housing and the syringe cartridge of FIG. 27 being removed from the separable base that remains attached to the patient. FIG. 29 shows a top plan view of another embodiment of the invention, of a device having a housing that can accommodate two syringe cartridges. FIG. 30 shows an elevation view of the device of FIG. 29. FIG. 31 shows a cross-sectioned elevation view of the dual-syringe device of FIG. 29 taken through line 31-31. FIG. 32 shows a separable base assembly having an adhesive flap for use in attaching the device of the present invention to the skin of a patient. FIG. 33 shows a cross-sectioned elevation view of the separable base assembly of FIG. 32 through lines 33-33. FIG. 34 shows a detailed cross-sectioned elevation view of the separable base assembly of FIG. 33. FIG. 35 shows another detailed cross-sectioned elevation view of the separable base assembly of FIG. 33. FIG. 36 shows a cross-sectional plan view of a base shown in FIG. 22 through lines 36-36, which has been modified to provide blocking plate that is in a deployment position to allow needle deployment. FIG. 37 shows a cross-sectional elevation view of the base of FIG. 36. FIG. 38 shows a cross-sectional plan view of the base of FIG. 36, which is in a blocking position to prevent needle deployment. FIG. 39 shows a cross-sectioned elevation view of an alternative embodiment of the device having an improved means for establishing liquid communication between the injection needle and the reservoir. FIG. 39A shows a detailed cross-sectional view of the device of FIG. 39. FIG. 40 shows cross-sectioned elevation view of an alternative embodiment of a syringe cartridge in a first configuration. FIG. 41 shows the syringe cartridge of FIG. 40 is a second configuration. FIG. 42 shows cross-sectioned elevation view of an alternative embodiment of the injection device having a means for selectively restraining the axial movement of the needle carriage. FIG. 42A shows a detailed cross-sectional view of the device of FIG. 42. FIG. 43 shows cross-sectioned elevation view of another alternative embodiment of a syringe cartridge. FIG. 44 shows cross-sectioned elevation view of an alternative embodiment of the device having a needle retracting means. DETAILED DESCRIPTION OF INVENTION DEFINITIONS As used herein, “patient” means a mammal, including a person, including a child or infant, or an animal, typically a mammal, on which the device is attached, and into whom the device injects an injectable liquid composition. As used herein, unless specified otherwise, the phrase “manually powered” means that the power provided to the device of the present invention to at least insert the injection needle into the patient's body is provided manually by a person, including a medical technician (a nurse, doctor, or other person who can administer the injection) or a patient, by manipulating the injection device with the hands or fingers, or by manipulating an appropriate implement that interacts with the device. As used herein, unless specified otherwise, the term “self-administering” describes the ability of the device of the present invention to be held or to hold itself in a position attached to the skin of a patient by a securement means, without requiring a medical technician, the patient, or other person, to hold the device, during the time that an injectable liquid composition contained within the device is injected into the patient through the injection needle. As used herein, unless specified otherwise, the term “upward” means in a direction or oriented away from the patient's skin or the base of the device; the term “downward” means in a direction or oriented toward the patient's skin or the base of the device; the term “inward” means in a direction or oriented toward the centerline of the device, typically the needle; and the term “outward” means in a direction or oriented away from the centerline of the device. The manually-powered, self-administering injection device of the present invention typically comprises a housing, an injection needle, a reservoir for containing an injectable liquid composition, such as a vaccine or a medicament, and a plurality of elements associated with and at least semi-permanently attached to the housing. The other associated elements can also include the various means of providing power or energy for the functional operations of the device, such as the insertion and retraction of the injection needle, and the pumping or injecting of vaccine to the injection needle. Typically, these associated elements are contained within the confines of the housing, although these elements can also partially confront or penetrate through the outer surface of the housing. In the course of administering most injections of vaccines and other medicaments, the injection can be advantageously administered intramuscularly (that is, into the muscle). The injection is made with an injection needle that is configured for insertion through the outer layer of the patient's skin, and more typically into the muscle tissue of the patient. Typically, the depth of insertion is at least about 5 mm, and typically up to about 35 mm or more, more typically from about 10 mm to about 25 mm, and even more typically from about 15 mm to about 20 mm. For a young child or infant, the depth of insertion is typically from about 10 mm to about 25 mm, more typically from about 12 mm to about 15 mm. Alternatively, some injections can be administered intradermally, or into other internal organs or the general body cavity of the patient. Painless injections can be achieved when the size or diameter of the injection needle is minimized, typically by using a needle of gauge size 28 or small (typically up to gauge size 33), and when the injectable liquid composition, such as a vaccine or other medicament, is injected at a volumetric flow rate significantly lower than that of a conventional injection made by hand, typically less than about 50 microliter per second (μL/s) and more typically about 1-4 μL/s. To achieve such low flow rates when administering a typical injection dose of between 0.5 ml to about 1.0 ml, an injection time of about 3 to 5 minutes may be needed. Typically, the human hand, using a conventional syringe, can not accurately or reproducibly control the flow rate within a range that ensures a painless injection. Furthermore, the desired slower injection rate of the medicament would require that the medical technician (or the patient) hold the conventional syringe carefully in place against the skin of the patient, and that the patient not move the limb or body part that is the site of the injection while the injection is being administered. The present invention overcomes these problems by providing a self-administering device that remains in position on the skin of the patient at the injection site, and administers the injection of the injectable liquid composition, without requiring a medical technician or patient to hold the injecting device in its place by hand, and without requiring that the patient remain still and not move while the injection is being administered. These problems are particularly troublesome when the patient is an infant or young child. The manually-powered device of the invention is intended to be attached semi-permanently to the skin of the patient before, during or after the injection. The device is typically configured to be attached to the upper arm or to the thigh area, providing access to the larger skeletal muscles (the deltoids and the quadriceps) for intramuscular injection. The attachment is preferably semi-permanent, whereby the device can be removed reasonably easily from the skin. The device is configured to attach to the body of the patient so that it does not move or migrate along the surface of the skin after attachment. In many situations, an adhesive attachment is sufficient. Alternative attachment means can include strapping, such as with a buckle strap or with a “hook and loop” attachment means commonly referred to as “Velcro”, or cuffing, as with a sphygmomanometer cuff. In an other alternative embodiment, a portion of the device, such as a bandage associated with the device or a portion of the base of the housing, can be configured to remain affixed to the patient's skin after the housing of the device has been removed. A typical adhesive for securing the device directly to the skin is a pressure sensitive adhesive (PSA). The direct-attaching PSA and the base where the PSA is affixed are typically configured whereby the PSA adheres to the device more strongly than the PSA adheres to the skin. The PSA is typically permanently affixed to the device, such that no PSA will remain adhered to the skin of the patient when the device, or at least the housing portion of the device, is removed from the skin. The PSA is also selected for a secure though releasable affixment to the skin. These criteria ensure that the device, or at least the bandage or base portion of the device, can be securely affixed to the skin for the vaccination procedure, and can be safely and efficiently removed from the skin thereafter. Typically, the manually-powered device having a skin-attaching PSA will also include a release member, such as a release paper or film, which overlies the adhesive on its skin-contacting side. After the release member is peeled from the PSA, the exposed adhesive layer can be placed against the patient's skin to attach the device thereto. A main objective for initiating the development of the present injection was effecting a painless injection of injectable liquid compositions. While pain can be a relative experience, typically the painless device of the present invention will, after having been secured to the skin of the patient, effect the insertion of the injection needle and injection of the injectable liquid composition into the body without a sensation or feeling of pain, and more typically without any sensation or feeling whatsoever. In other words, the patient in most circumstances will have no sensation that the device has inserted a needle into the body, or that the injectable liquid compositions is or has been injected into the body, except perhaps visually observing the device or touching the device with a hand, or feeling the attachment of the device to the outside of the skin. Typically the manually-powered device is configured to complete the vaccination or injection of medicament into the patient utilizing a source of power or energy that is external to the device itself. The source of power can be provided by a person, such as a medical technician (a nurse, doctor, or other person who can administer the injection) or the patient, typically by manually (or bodily) manipulating the injection device with the hands or fingers, or by using an appropriate implement, as hereinafter described. The self-administering feature of the device and method of the invention enables injection of injectable liquid compositions without requiring medical personnel to hold the device against the skin of the patient during the time that the injectable liquid composition is in liquid communication with the needle, and is being pumped from the device into the patient. The use of the device that self-administers an injection allows medical personnel to perform other tasks while the injection proceeds. The device also allows the patient to have freedom of movement for the minutes of time that the injection proceeds. Typically, the source of power for arming the manually-powered device from its unarmed configuration comprises a manual power. This can be the use of the hands or fingers of a technician or an adult patient to manipulate the device or elements thereof with force. The manipulating force can also be applied using an implement, such as a key, push rod, or other inanimate object. The manually-applied kinetic force is stored by a power means within the device as potential energy, which can, upon subsequent activation, power one or more of the functions of the device. Typically, the external force used for the needle insertion function can also be used to store potential energy within the device, such as in a compressed spring or other biased resilient member. The external force can also be stored as electrical power or pneumatic power. Typically, the device is manufactured and shipped to a use center, such as a clinic or hospital, with the needle insertion function in a first unarmed configuration. The unarmed configuration provides that the injection needle, which in its first position has it's the distal end or tip of the injection needle wholly within the housing, can not be intentionally or accidentally extended to a second position wherein the injection tip extends through the base of the device and outside of the device. In the unarmed configuration, there is typically no potential energy source, such as a compressed wire spring, available to the needle insertion means for spontaneous insertion of the needle. The unarmed condition can also be termed a fail-safe position, since, in this configuration, even a malfunction of the device will no allow the needle to extend from the housing. By contrast, if the needle insertion means is armed, then the device has potential energy stored on board, such as in a compressed, extended or torsioned spring, or other power means for insertion of the needle. If this armed device is activated, such as when an actuation button is depressed, the potential energy of the power means is released as kinetic energy that can move the needle insertion means from its first position to its second, extended position. If the device is shipped, stored, or handled in an armed configuration, there is a risk of an inadvertent, or even an intentional, activation of the needle insertion means. Consequently, the shipment and handling of the manually-powered device of the present invention in an unarmed configuration can avoid both an intentional and accidental needle sticks prior to its use in administering an injectable liquid composition. This improves the safety and security of the device during, storage, and pre-injection handling. In this configuration, at least the needle extension function (also called the insertion function when the needle tip extends into the skin of the patient) is unarmed. Other functions, such as the pumping or injection means (for passing the injectable liquid composition through the injection needle) and the needle retracting means (to withdraw the needle from its second position in the body, back toward its first position in the housing) can be configured for shipment and storage as either armed or unarmed. Preferably, the power means for the pumping means has an unarmed configuration, to avoid an accidental activation of the pumping of injectable liquid composition from the reservoir, which could prematurely empty the reservoir and render the device useless. Likewise, any needle retracting means is preferably shipped and stored in an unarmed configuration, to avoid the possibility of an unintentional or accidental activation, which in some embodiments may make the opposing needle insertion function inoperable, where the needle retraction is irreversible. The power means can be used to provide energy to one or more of the elements of the device, such as insertion and retraction of the injection needle, or pumping of the medicament. Two or more power means can be used to provide energy for different elements, such as where the injection needle is moved from one position to another by a first power means, and an injectable liquid composition is pumped from a reservoir to the injection needle by a different, second power means. The device can be at least partially self-controlled, wherein at least one of the elements of the device can initiate operation automatically in response to the operation of another element. The typical device of the present invention has a housing comprising a base for placement against the skin of a patient, for attachment of the device. The base can have a contoured surface that generally conforms to the shape of the body (typically, the arm or leg), to maintain the base surface in optimum confronting relationship with the skin. For example, the base of the device can have a slightly concave surface, which arches inwardly toward the interior of the housing. The housing is typically made of a thermoplastic material that is light and inexpensive to manufacture, such as by molding, and yet is durable and resilient to gross deformation or breakage. A typical plastic material can include polyethylene, polypropylene and polycarbonate. The housing can be designed with a shape that is both aesthetically pleasing and functional, for example, to allow insertion of the reservoir, to allow activation of one or more of the elements, such as the injection needle and liquid communication means, and other elements of the device. The housing can be made as a single part or as a plurality of parts configured to associate and secure together in both either static or moving relation to one another. The housing also provides a visual enclosure for the injection needle that keeps the needle out of sight of the patient at all times during the injection procedure. This can reduce or eliminate the patient's apprehension or fear caused by the sight of a needle, thereby reducing the tendency of the patient's muscles to tighten and harden, which can make needle penetration more difficult and painful for the patient. The housing also provides a physical enclosure for the injection needle that helps to avoid accidental needle stick, particularly after an injection, which could place a user at serious risk from fluid-borne pathogens. The device can be configured for use only once (unless completely disassembled and retrofitted), thereby minimizing the likelihood of reuse of a contaminated hypodermic needle. The device can also advantageously be configured wherein some parts or assemblies, such as the housing and it associated elements, can be reused. The housing can also be configured to receive and secure the needle and optionally the reservoir of injectable liquid composition as a modular insert into the housing body. The housing can include two or more parts, at least one of which is movable relative to another, which can be configured into an open position wherein either the needle or the reservoir, or both, can be inserted into the body of the housing, or a closed position wherein the needle and/or reservoir are not accessible or retrievable from within the housing. The movable part can be a door or a panel that is movable to provide an access port into the housing. The door or panel can be hinged or removably affixed to the housing, or can be slidable away from the access port. The injection needle of the device provides for liquid communication of the injectable liquid composition passing from the reservoir and through other liquid communication means of the device, into the body tissue of the patient, from where the injectable liquid composition can dissipate into the surrounding tissue and throughout the body. The injection needle should be shaped and configured to provide painless insertion and painless injection of the injectable liquid composition. Generally an injection needle having a smooth circular outer surface and an outer diameter D of about 0.36 mm (28 gauge needle) and less can be inserted painlessly through the skin of a patient. For small children, infants and patients having more sensitive skin, an outer diameter D of about 0.30 mm (30 gauge needle) and less (31 gauge to 33 gauge), will typically ensure painless needle insertion. Typically the injection needle is configured to be substantially linear or straight, from its distal end or tip, toward the opposed inlet opening. The needle can be configured to be linear completely to its inlet end, or can be configured with a bent or curved portion near the inlet opening. The needle size should be sufficiently large to allow passage of the required volume of liquid medicament into the body within a period of time that is suitable to avoid causing pain. For a typical medicament volume of about 0.5 ml to about 1.0 ml, a substantially painless to completely painless injection can be achieved over an injection period of from about 1 minute to about 10 minutes, more typically from about 3 minutes to about 5 minutes. The volumetric flow rate is at least about 0.05 microliter per second (μL/s), and up to about 50 μL/s. Typically, the volumetric flow rate is about 0.5 μL/s to about 20 μL/s, and more typically about 1 μL/s to about 4 μL/s. The injection needle should be sufficiently durable and axially rigid to avoid bending or breaking when inserted into the skin and muscle. Typically, a needle having an outer diameter of from about 0.10 mm (about 36 gauge), more typically of from about 0.23 mm (32 gauge), up to about 0.36 mm (28 gauge), is sufficiently painless, durable, and liquid conductive. It is also within the practice of the device and method of the present invention to inject medicament volumes of greater than about 1.0 ml, and to deliver the injection over time periods greater than 10 minutes. Typically, the injection needle is pre-installed into the injection device during its manufacture, prior to its distribution to the facility or site where the injection shall occur. Although the device can be configured for installation of the injection needle at the use facility, the small, fine size of the injection needle may make it difficult for a medical technician or patient to manipulate it into position within the device. Likewise, after a vaccination, the injection needle and the housing or assembly thereof into which the needle is secured, can be disposed of in accordance with health and safety regulations and guidelines. The injectable liquid composition is typically contained within the cavity of the reservoir, and flows from the reservoir to the injection needle during injection. The reservoir is typically positioned within the housing although the structure of the reservoir can also form a portion of the outer surface of the housing. The reservoir can have a rigid structure having a fixed volume with a moveable member, such as a plunger that defines a variable volume cavity. The reservoir can also have a flexible structure where its volume can decrease as its content of injectable liquid composition is removed there from. Typical materials for use in making the reservoir include natural and synthetic rubber, polyolefin, and other elastomeric plastics. The selection of the structure and material of construction of the reservoir will depend in part on the specific means of pumping the medicament from the reservoir to the injection needle. Selection of the material of the reservoir should also be chemically stable with the injectable liquid composition. In another typical embodiment, the reservoir can be affixed to the injection needle as part of a injectable liquid composition product, for assembly into the device. A reservoir will generally have a volume sufficient to contain about 0.1 ml to about 10 ml, typically about 0.1 ml to about 3 ml, of medicament. In a more typical embodiment, the reservoir would hold about 0.5 ml to about 1.0 ml of medicament. The reservoir comprises an outlet port that is in liquid communication with, or can be brought into liquid communication with, the injection needle. The reservoir outlet can be temporarily sealed, such as with a penetrable membrane that can provide an air-tight and leak-proof seal over the outlet opening of the reservoir during manufacture, shipment and storage of the filled reservoir, and that can provide a self-sealing, leak-proof joint when pierced by the inlet end of the needle or a separate piercing conduit at the time of the injection. A typical reservoir membrane comprises natural or synthetic rubber or a thermoplastic material. Alternatively, a wall of the reservoir can be adapted to allow penetration thereof by the piercing conduit, such as the inlet end of a needle. A typical embodiment of a reservoir comprises a reservoir body having a cavity that has been pre-filled with the injectable liquid composition and sealed. The pre-filled reservoir can be assembled into the device during manufacture. In this case, the device is labeled to identify the particular injectable liquid composition that is contained therein. More typically, pre-filled reservoir will be configured for installation or insertion into the housing of the injection device at the facility or site where the injection will occur. The technician would typically remove the reservoir from a storage area, such as a refrigerator, and insert it into position within the housing of the device. An identity label associated with the reservoir can be provided that is conveniently transferred to the patient's records. Alternatively, a device can have secured within an empty reservoir can be filled by medical personnel with the appropriate quantity and type of medicament, prior to injection. Typically, this embodiment of the reservoir comprises a liquid flow valve that has a self-closing, self-sealing opening to the cavity of the reservoir. The flow valve can be a one-way flow valve, also referred to as a check valve. The liquid composition flow valve is typically an elastomeric or rubber material. One type of one-way flow valve is a flapper or so-called duckbill valve (available from MiniValve International Yellow Springs, Ohio) that allows flow of liquid in one direction, but which self-seals in response to liquid flow or pressure in the opposite direction. Another type of one-way flow valve is a cylindrical member having a slit opening formed axially there through, through which a hypodermic needle of a syringe is inserted to inject a desired dose of the liquid composition into the cavity of the reservoir. When withdrawn, the slit opening closes and seals. When the device is used by medical personnel as supplied from a manufacturer with the reservoir securely inserted within the housing, the device can have a companion flow valve in communication with the reservoir flow valve that is disposed in the outer surface of the housing, or otherwise accessible to the medial personnel. The liquid composition flow value can be inserted into a bore formed in the sidewall of the reservoir that is slightly smaller in diameter than the flow valve. If the reservoir is configured so that a portion of the reservoir is integral with the housing, then a single flow valve can be used, with an inlet accessible to the medical technician and an outlet into the cavity of the reservoir. Alternatively, the device can be configured with a second liquid composition flow valve positioned in the housing, disposed adjacent to and aligned with the first flow valve disposed in the reservoir. An important requirement of the liquid communication means is to ensure that the liquid composition can flow from the reservoir to the injection needle regardless of the specific orientation of the device. Typically, the attachment of the device to the skin of the patient can position the reservoir and the injection needle into a variety of relative spatial orientations that can sometimes require the liquid composition to flow upward against gravity, or that can position the outlet of the reservoir in an upward position, opposite the pool of liquid composition disposed in the reservoir. Consequently, a preferred configuration of the reservoir and liquid communication means provides that the outlet of the reservoir is maintained in communication with the remaining liquid composition in the reservoir. A typical configuration comprises a collapsible reservoir comprising an outlet that maintains liquid communication with any residual liquid composition present in the reservoir. This reservoir has an upper flexible wall that can be conformed to the volume of the liquid remaining therein. The reservoir typically contains little or no air or gas when filled with the supply of liquid composition and during its displacement and injection operation. Thus, the reservoir collapses to become essentially empty, terminating delivery. In like manner, when a non-flexible material is used for a reservoir, such as a conventional tube-with-plunger syringe, the displacement of the plunger empties the reservoir, which terminates delivery. The housing can also comprise an outer support structure that confines and protects the reservoir from outside elements that might puncture it, and which can define the initial shape of the reservoir. The reservoir can also be constructed of an elastomeric material that can be expanded in volume when filled with the liquid composition, and holds the liquid composition under pressure. After puncture by a piercing conduit, such as the inlet end of the injection needle or an intermediate member that is in liquid communication, such as via tube, with the injection needle, the expanded reservoir can contract to reduce the effective volume of the reservoir as liquid composition is pumped there from. One or more of the walls of the reservoir can be made of an elastomeric material, while other walls or surfaces are made of other elastic or inelastic rubber or plastic material. The reservoir can also comprise an adaptable structure having a means of varying its effective volume, such as a piston-plunger construction or an accordion construction, as in a bellows. In the embodiments described herein, a self-contained reservoir can be replaced with a more conventional syringe and plunger for storing and injecting the liquid composition to the injection needle. Non-limiting examples of a reservoir of the present invention are those described in U.S. Pat. No. 5,527,288 (element 10), U.S. Pat. No. 5,704,520 (element 12), and U.S. Pat. No. 5,858,001 (elements 16 and 17), all such publications incorporated herein by reference. A first embodiment of the invention is shown in FIGS. 1-3, 3A, and 4-28. The device includes a housing, shown in FIGS. 1-3, 3A, and 4-9, and a cylindrical syringe cartridge shown in FIGS. 10-19. The use and operation of the device for manually self-administering a painless injection is illustrated in FIGS. 20-28. A device having a housing for retaining a plurality of cylindrical syringe cartridges is shown in FIGS. 29-31. FIGS. 32-25 show a separable base and means for attaching the device to a patient's skin. FIGS. 1-8 show an assembled housing 10 in various views and aspects. FIG. 1 shows the housing 10 having an outer body 11, a needle carriage 70, a means for retaining a reservoir for an injectable liquid composition, and a base 12 for placement of the device against the skin of a patient. The carriage 70 is configured for movement along an axial centerline 100 in a direction perpendicular to the base 12. The cylindrical carriage has a cylindrical recess 71 having a tapered bottom 78, that opens to a connector portion 73 having internal female threads, which provide the at least a portion of the retaining means for the reservoir, described below. A needle 40 lies along the centerline 100 and is disposed through the axial center of a needle hub 72 that is secured to the connector 73. The inlet 42 end of the needle 40 extends within the connector portion 73 sufficiently below the opening in the tapered bottom 78 to prevent the sticking of a finger that may probe the recess. A retracting spring 76 is positioned about the centerline 100, having one end disposed within an annular groove 74 in the underside of carriage 70, and the other end disposed around an annular flange 94 projecting up from the base 12. The needle 40 extends downward from the lower end of the needle hub 72 toward the base 12. The needle is completely within the housing when the carriage 70 when in the first retracted position shown in FIG. 1. As will become more evident, the retracting spring 76 disposed as shown in FIGS. 1, 3, and 20 should have an amount of pre-tensioning or compression that is sufficient to completely retract the carriage 70 back to the top of the housing 10 when the needle 40 is retracted from the body. In a second inserted position, shown in FIG. 2, the carriage 70 has moved axially toward a position proximate to the base 12 of the device, and the needle 40 extends downwardly and out through the opening 13 in the base. The guide wall 14 comprises an inwardly-projecting, axially-oriented guide, shown as elongated rib 19, that registers along its length with an axially-oriented peripheral groove 77 in the outer wall 75 of the carriage 70, shown in FIG. 3, to prevent the carriage 70 from rotating within the guide wall 14. A retainer heel 86 is biased inward from an opening in the cylindrical guide wall 14. As the carriage 70 passes down the guide wall 14, the heel 86 is temporarily biased outward, allowing the carriage to pass. The retracting spring 76 is compressed between the underside of the carriage 70 and the base 12. When the carriage arrives at the fully inserted position shown in FIG. 2, the lower end flange 79 of the carriage has cleared past the heel 86, which returns to its inwardly-biased position, where it can secure the carriage 70 and the needle 40 in the inserted position, and secures the retracting spring 76 in a compressed state. The heel 86 is part of a release arm 80, described herein after. FIG. 4 shows a plan view of the housing 10 in its first retracted position, with selected cross-sectional views taken as FIGS. 1, 3, 5, and 6 to illustrate certain elements of the housing. FIGS. 7 and 8 are sectional views of the housing in FIG. 1. An exploded view of the elements of the housing 10 is shown in FIG. 9. FIGS. 10 and 11 are sectional views of the syringe cartridge 18 taken through perpendicular section lines 10-10 and 11-1I of FIG. 12. FIGS. 13-17 provide additional detailed views of the syringe cartridge 18 shown in FIGS. 10 and 11. FIG. 18 shows an exploded view of the elements of the syringe cartridge 18. The syringe cartridge 18 shown in FIGS. 10 and 11 comprises a syringe assembly 20 and a telescoping pressurizing assembly 30, configured as a reservoir having liquid cavity 66 for the injectable liquid composition. The syringe cartridge 18 is configured to be associated with and retained within the housing 10 of the device. In the illustrated embodiment, the cylindrical recess 71 of the needle carriage 70 provides the means for retaining the reservoir of injectable liquid composition, embodied by the syringe cartridge 18. The syringe assembly 20 comprises a syringe body comprising a cylindrical wall 21 that has an open upper end 25 and a tapering base 22 that has, at the lower end, an externally-threaded syringe port 64 having an aperture 23. A cylindrical plunger 24 can be inserted through the opening in the upper end 25 for engagement with the inner surface of the wall 21. The space between the plunger 24 and the syringe body in FIG. 10 defines the reservoir cavity 66. The respective threads of the syringe port 64 of the syringe cartridge and of connector portion 73 of the needle carriage cooperate and engage when the syringe cartridge is placed into the needle carriage and rotated, which secures or locks the syringe cartridge into its retained position within the needle carriage. The cooperating threads also provide liquid communication between the injection needle and the reservoir of the syringe cartridge, as the inlet 42 end of the needle advances and penetrates a membrane 65 of the membrane plug 67 disposed in the opening of the syringe port 64 (see FIG. 14). The plunger 24 is typically a flexible, resilient rubber material that can form an effective liquid seal about its periphery with the sidewall 21 of the syringe. The plunger 24 is secured around a rigid plunger plug 26 to maintain its cylindrical shape. As can be seen in greater detail in called-out FIG. 13, the inner surface of the syringe wall 21 has, at its upper end, a slight inwardly-extending rim 38 that can engage the upper end of the outer wall 43 of the plunger 24, which can prevent the plunger 24 from incidentally withdrawing from and falling out of the upper opening of the syringe wall 21. Nevertheless, the plunger wall 43 is sufficiently flexible to be inserted into or extracted out of the syringe opening by force. The threaded bore in the plunger plug 26 is provided for attachment of a stem (not shown) having a mating thread so that the plug 26 and the plunger 24 secured thereto can be manipulated into and out of the syringe opening, and along the length of the syringe. The telescoping pressurizing assembly 30 comprises a cylindrical body 31 that is closed at an upper end 34 and has an opening 32 at the opposed lower end. The lower edge of the cylindrical body 31 has a pair of opposed mechanical engaging means shown as inwardly-extending ribs 36 that can engage an outwardly-extending rim 28 disposed on the upper end 25 of the syringe wall 21, to secure the pressurizing assembly 30 to the upper end 25 of the syringe assembly 20 in a first extended position, as shown in FIGS. 10 and 13. A pressurizing spring 33 is restrained within the body 31 between an annular groove 35 at the closed end 34, and an annular groove 27 in the plunger plug 26. When the pressurizing assembly 30 is in the extended position shown in FIG. 10, the pressurizing spring 33 is typically under minimal compression. Nevertheless, this amount of pre-tensioning or compression of the spring 33 should be sufficient to maintain an adequate rate of flow of liquid composition from the cavity 66 at the end of the injection term, as shown in FIG. 25. FIG. 11 shows the same syringe cartridge as in FIG. 10, but with the plunger 24 and the pressurizing spring 33 extended to the bottom of the syringe body 21. In this configuration, a medical technician can fill the syringe assembly. The upper pressurizing assembly 30 and the membrane plug 67 are first removed. Then, using a threaded stem (not shown), the plunger can be pulled upward to draw in injectable liquid composition through the aperture 23. The membrane plug 67 and the upper assembly 30 can then be reinstalled. The wall 31 of the pressurizing assembly 30 is configure to telescope axially over the outside of the syringe wall 21 to a second pressurizing position (shown in FIG. 19) where the ribs 36 can engage a second set of outwardly-extending rims 29 disposed near the lower end of the syringe wall 21, also shown in FIG. 10. This causes the closed upper end 34 of the pressurizing body 31 to compress fully the pressurizing spring 33 against the plunger plug 26, which causes the plunger 24 to move to the bottom 22 of the syringe 21 when no liquid is contained in the cavity 66 of the syringe. The engagement of the ribs 36 with the lower rims 29 retains cylindrical body 31 in the fully pressurized configuration. When the cavity 66 of syringe 21 contains a volume of injectable liquid composition, such as vaccine V as shown in FIG. 19, the manual depressing of the syringe cartridge causes the compression of the pressurizing spring 33. The engagement of ribs 36 with rims 29 restrains the compressed pressurizing spring 33, and retains the potential energy within the compressed spring 33 as a means for injecting the liquid composition from the retainer. The manually-powered, compressed spring 33 exerts a downward force upon the plunger 24, which exerts pressure upon the liquid composition in the cavity 66. When the cavity 66 is put into liquid communication with the needle, the pressurized liquid composition can flow out of the cavity 66 under pressure. The pressurizing spring 33 is configured and designed to maintain a relatively constant force, resulting in a relatively constant pressure and liquid composition flow rate through the needle throughout the injection process. Optionally, the device 1 of the present invention can comprise a separable base 92, from which the housing 10 can be removed at any time, particularly and advantageously after completion of the injection. The separable base 92 is typically configured for separable securement to the base 12 of the housing by a base securement means, and typically provides the skin-contacting surface of the device 1. A base separation means provides selective separation of the separable base 92 from the device. FIGS. 2, 27 and 28 illustrate an embodiment of a separable base 92, as embodied in a separable attachment assembly 93 that removably associates with the base 12 of the housing 10. The base securement means can comprise a mechanical engagement, such as a catch 89 formed on a distal end of a release finger 88 that depends downward from a portion of the housing body 11. The distal end of the finger 88 extends through an opening 95 in an inner base member 91 shown in FIG. 2. The finger 88 further extends through an opening 98 in the removable base 92 when the removable base 92 is positioned against the base 12 of the housing. The finger 88 is configured to bias the catch 89 toward and into engagement with a latch 96 formed in the separable base 92, shown in FIG. 27. The separable base 92 remains affixed to the housing of the device provided that the catch 89 remains engaged with the latch 96. The base separation means for separating the separable base 92 from the permanent housing base 12 can comprise a mechanically-biased member associated with the housing 10 that is configured for manipulation that forces to disengage the base securement means, specifically in the illustrated embodiment by moving the catch 89 out of engagement with the latch 96. In FIG. 27, after the needle 40 and carriage 70 have been retracted, the person can depress the release button 81 even further, thereby causing a toe 87 on a release arm 80 to pivot into engagement with the release finger 88, and to bias the catch 89 out of engagement with latch 96. With the catch 89 disengaged from latch 96, and with the needle 40 fully retracted, the housing can be safely and easily separated from the separable base 92 for post-injection inspection, and for disposal. The separable base further comprises a means for attachment to the skin of the patient. Typically, the means for attachment comprises an adhesive means adhered to the skin-contacting surface of the separable base. While the figures and associated description describe the separation of the separable base from the housing while the device is attached to the skin of a patient, it can be understood that the separable base can also be removed from the housing while the device is free from attachment to the body. In a method of using the device of the invention, a device 1 is provided as shown in FIG. 20 comprising a housing 10 having an optional separable attachment assembly 93 comprising a separable case 92, and a syringe cartridge 18. The three members are shown separated to illustrate, that prior to use as an assembled product, the components can be separated and visually inspected. The separable attachment assembly 93 can be attached manually to the base 12 of the housing 10 as previously described. Prior to attachment of the device to a person, a release paper 111 that covers the separable base 92 and adhesive flaps 112, is peeled away and disposed of. As shown in FIG. 21, the separable attachment assembly 93 of the housing 10 can be attached to an area of the patient's skin on the upper arm or leg of the patient P, designated as the injection site, secured by the adhesive on the underside of the adhesive flap 112 that extends outward from the periphery of the separable base 92. After attachment of the device to the skin, a seal 105 is removed that covers the opening to the carriage recess 71 to protect the inlet end 42 of the needle 40 from contamination, as shown in FIGS. 21 and 22. The syringe cartridge 18 is then inserted into the recess 71 of the carriage 70. The threaded syringe port 64 engages the threaded connector 73, so that manual axial rotation of the syringe cartridge 18 mates the respective threads and secures the syringe cartridge 18 to the carriage 70. As that occurs, a membrane 65 disposed in the opening of the syringe port 64 (see FIG. 14) is penetrated by the inlet 42 end of the needle, which establishes liquid communication with the syringe cavity 66. A pair of tabs 45 extending out from the top of the pressurizing body 31 provides a grip for manually rotating the syringe cartridge 18 into the carriage 70. Relative axial rotation between the syringe assembly 20 and the pressurizing assembly 30 is prevented by disposing the outwardly-extending rims 28 of the syringe wall 21 into longitudinal grooves 37 formed in the inner surface of the pressurizing body 31. In an alternative method, the syringe cartridge 18 can be provided in its pressurized configuration, as shown in FIG. 19, just after the technician has compressed the telescoping pressurizing assembly 30 down onto the syringe assembly 20, and just prior to insertion of the cartridge 18 into the carriage 70, shown in FIG. 22. When the technician inserts the pressurized cartridge 18 into the recess 17 of the carriage 70, and rotates or twists the cartridge 18 to establish liquid communication between the reservoir cavity 66 and the needle 40, liquid composition may begin to flow from the syringe cavity and into and through the needle 40. The device can also be configured to prevent rotation and removal of the modular syringe from its position in fluid communication with the needle, once the carriage 70 has been moved to and secured in the injection position. The tabs 45 extending from the closed end 34 of the pressurizing assembly 30 nest within the oblong recess 17 in the top of the housing 10 to inhibit finger access to the assembly, and to prevent manual rotation and removal of the syringe cartridge 18 in the injection position. This prevents an unwanted exposure of a needle that is penetrating the skin from being open at its inlet 42 end to the atmosphere. As shown in FIG. 23, the needle 40 is then inserted into the patient by manual force downward on the syringe cartridge 18 to move it into the housing 10 and toward the base 12, thereby inserting the injection needle 40 into the body and initiating the injection. The pressing downward of the syringe cartridge 18 has also compressed the retracting spring 76. Fully manually pressing the syringe cartridge 18 downward causes the carriage 70 to be retained in a second position associated with the second injection position of the injection needle. A needle insertion securement, such as the retainer heel 86 shown in FIG. 24, is configured to retain the needle carriage, and the injection needle, in the second, inserted position while the liquid composition is injected. Under the relatively constant force of the pressurizing spring 33, the vaccine V is slowly though constantly expressed out of the syringe cavity 66 and into the targeted body tissue 150. The size of the needle 40 and the force factor of the pressurizing spring 33 can be configured and designed to cause the liquid composition to flow under pressure through the needle within a target volumetric flow rate, to complete the injection within a prescribed period of time. At the end of the injection term, shown in FIG. 25, the plunger 24 has moved under the force of spring 33 to the bottom 22 of the syringe, and has collapsed the reservoir cavity 66 and driven substantially all of the vaccine out of the syringe cartridge 18. An alternative method of inserting the needle 40 can employ the syringe cartridge 18 itself as an implement or plunger for depressing the needle cartridge to its inserted position, without having the needle inlet 42 penetrate the membrane 65 to the syringe cavity and placing the needle into liquid communication with the cavity. The syringe port 64 of syringe cartridge 18 can be rested against the bottom of the carriage 70, as shown by the left-side syringe in FIG. 31, and pressed downward without having engaged the threads, or having only partially engaged the threads, of needle hub 72 and connector 73. Alternatively, the syringe port 64 and the connector 73 can be configured to provide a first position wherein the threads partial engage without establishing liquid communication between the needle and the cavity (that is, without rupturing the membrane 65), and a second position wherein the threads further engage and establish liquid communication by penetration of the membrane by the inlet end of the needle. Once the injection has been completed, or at any time during the vaccination, the needle can be retracted from its second or inserted position by activating a needle retracting means. The needle retracting means can comprise a disengagement means that is configured to disengage the needle insertion securement, and a power means configured to bias the needle, and the needle carriage, to respective third positions where the injection end of the needle is disposed within the housing. In the illustrated embodiment of FIG. 26, the disengagement means comprises one or more release arms 80 and one or more release buttons 81. The release arm 80 comprises an upper end 82 shown as a ball having an inward flat surface that is secured within a socket 15 formed in the main body 11. The release arm 80 also comprises a pivot 83 that resides in a detent in the outside of the guide wall 14, and a resilient, flexible elbow portion 84 intermediate the ball end 82 and the pivot 83. A lateral bar 85 on the inside of the release button 81 is disposed proximate the elbow 84. In response to an inwardly-directed force on the button 81 that moves the button inward, as shown in FIG. 26, bar 85 causes the release arm 80 to flex inwardly at the elbow 84, causing heel 86 to pivot outwardly and out of engagement with the carriage lower flange 79. As shown in FIG. 27, the power means comprises a compressed retracting spring 76 that had been manually disposed into a compressed configuration when the needle was manually inserted, and biases the needle toward a third position. With the needle carriage 70 unsecured by the needle insertion securement, retainer heel 86, the compressed retracting spring 76 can drive the carriage 70 upward from the base 12, and retract the distal end of the needle, needle tip 41, completely out of the body of the patient P and into the third position where the needle tip is within the housing 10. As described earlier, the retracting spring 76 should be disposed within the housing 10 with an amount of pre-tensioning or compression that is sufficient to completely retract the carriage 70 back to the top of the housing 10, so that the needle 40 will be retracted completely back into the housing. The needle insertion securement and the disengagement means can function through or comprise the same element of the device (like the release arm 80 which functions to both secure the carriage and to disengage the securement), or can employ distinct elements. After retraction of the needle 40, the syringe cartridge 18 can be grasped and removed by oppositely rotating the cartridge to disengage the threaded connection of the cartridge with the carriage. The cartridge assembly 18 can be inspected to confirm that all the liquid composition from the syringe cavity 66 had been injected, and then is disposed. If for any reason a significant amount of the liquid composition remained in the syringe, the syringe cartridge 18 can be reinserted into the carriage 70 and again rotated into liquid communication with the inlet of the needle 40, and the carriage and needle reinserted into the patient to complete the injection. The illustrated embodiment shown in FIGS. 5, 25 and 27 shows that the release button 81 can have a generally cylindrical shape. The button can have a main inner wall 104 and an annular outer wall 101 having an annular periphery that is slightly larger than the annular opening 102 in the housing body 11 in which the button is disposed. The flared outer wall 101 resist movement of the button 81 into the opening 102 until a manual force is applied that is sufficient to bias inward the outer wall 101. As the button 81 is depressed, it biases elbow 84 of the release arm 80. When the force on the button 81 is released, the resilient elbow 84 will spring back against, and move, button 80 outward to its original position. The button 81 can also provided with a small aperture in its face, through which a small hooked implement can be inserted to pull out the button if it should become lodged inwardly. In an alternative embodiment of the device, the means for establishing liquid communication can comprise a separate piercing conduit for establishing liquid communication with the reservoir, and which is in liquid communication with the injection needle. FIG. 39 shows a carriage 70 having a connector portion 73 that comprises a piercing needle 120 configured to penetrate a seal or membrane in the syringe cartridge 18 (not shown), and which is in liquid communication with the inlet end 42 of the injection needle 40. FIG. 39A shows in more detail a needle hub 72 positioned within a recessed bore in the end of the connector portion 73. The inlet end 42 of the needle 40 is flared so that the injection needle is retained within the needle hub 72. A conduit hub 121 is securely positioned over the needle hub and retains the piercing needle 120 in position. The distal end 122 of the piercing needle 120 is typically sharpened or pointed to facilitate penetration of the liquid seal or membrane. The piercing needle 120 is typically of a smaller gauge (larger diameter) than the injection needle to ensure penetration of the liquid membrane without crimping or bending. Alternatively, the injection needle 40 can be made with an integral piercing conduit at the inlet end 42 that has a larger diameter and thickness than the skin-inserted portion of the needle. Another alternative embodiment of the device can comprise the syringe cartridge shown in FIG. 40. The syringe cartridge 218 illustrated comprises a body having a cylindrical wall 221, a tapered base portion 222 having an aperture 223, and an upper closed end 234. The syringe cartridge 218 also comprises a plunger 224 that is configured for axial movement along the length of the cylinder wall 221. FIG. 40 illustrates the plunger 224 both at a first position prior to filling of the cartridge reservoir with liquid composition, and at the end of the injection when the last amount of liquid composition has been evaluated from the cavity 66. A pressurizing spring 233 is disposed within the cartridge between the plunger 224 and the closed end 234, and is typically pre-tensioned to maintain a minimal force upon the plunger 224 when the plunger is in the first position. The cartridge 218 also comprises an outlet connector 264, comprising a one-way flow valve 267, illustrated as a duckbill valve having confronting flaps 268a and 268b. The syringe cartridge 218 shown in FIG. 40 is in its configuration prior to filling. The medical technician or patient can draw the injectable liquid composition from a source, such as a glass vial, into a standard syringe (not shown) fitted with an outlet connector, such as a threaded female luer connector, that can be secured to the outlet 264 of the cartridge 218. After sealably connecting the supply syringe to the outlet port 264 of the cartridge 218, the person depresses the stem of the supply syringe plunger, causing the liquid composition to flow under pressure through the one-way valve 267 and into the cartridge. The pressurized composition moves the plunger 224 toward the closed end 234 and forms the reservoir of liquid composition V within the cavity 66. The pressurized composition also compresses the pressurizing spring 233 back toward the closed end 234. When the force applied to the plunger stem of the supply syringe is released, the pressurized liquid composition within the cavity 66 collapses and closes the one-way valve 267, as shown in FIG. 41. The one-way valve 267 can be positioned so that the inlet end 42 of the needle or the piercing needle 120 can penetrate the flappers 268 sufficiently to establish liquid communication. The filled cartridge 218 can then be inserted into the housing as described herein before. In another alternative embodiment of the invention of a dual-port syringe cartridge 318. The dual-port cartridge has a first port 323 at a first end of the cartridge, configured for filling the cartridge with liquid composition V, and a second opposed port 364 at a second end of the cartridge, configured for dispensing the liquid composition from the reservoir to the injection needle 40. The cartridge 318 comprises a plunger 324 disposed in the cartridge for movement toward the first end for dispensing the liquid composition from the cavity 66. The plunger 324 is associated with a liquid dispensing means shown as pressurizing spring 333 for maintaining pressure upon the composition V within the cavity 66 to cause the liquid composition to flow from the cavity. The pressurizing spring it typically pre-tensioned to ensure sufficient force is exerted through the entire length of the plunger travel to maintain adequate liquid flow through the injection needle. The cartridge 318 comprises a means to establish liquid communication between the first or filling end of the cartridge, and the second or dispensing end of the cartridge. This liquid communication means can comprise a flow channel 341 in liquid communication between the distal end of the cavity 66 and the dispensing end 364 of the cartridge. In the illustrated embodiment, an tube 342 having the flow channel 341 is secured to the second end 322 of the cartridge, and extends to a distal end 343 that terminates proximate the inlet port 323. The dip tube 342 is preferably aligned along the axial centerline of the cartridge. In the illustrated embodiment, the plunger 324 is configured with an orifice through its longitudinal centerline, and forms an annular liquid seal 326 with the outside surface of the dip tube 342 and a peripheral seal 325 with the inside of the cylindrical wall. The filling port 323 can be fitted with a one-way valve 357 and filled as described above. As the reservoir is filled under pressure, the pressurizing spring 333 compresses toward the dispensing end 322. The one-way valve 357 seals inlet port 323 to prevent leakage of the pressurized liquid V within the cavity 66. The membrane seal 367 seals the outlet port 364 and maintains the cavity of the filled cartridge 318 under pressure. The filled cartridge can then be inserted into the housing of a device as described herein. An optional cap 334 can be secured to the filling port 323 after filling to prevent curious fingers form pulling on the cartridge during injection. The illustrated cartridge 318 in FIG. 43 provides distinct features that can be advantageous. The cartridge has separate and spaced-apart filling and dispensing ports, which can allow the cartridge to be filled after it has been positioned and secured to the device. This avoids the need to handle the cartridge after it has been filled. The filling port 323 is typically oriented toward the top of the device. The configuration of the cartridge also provides for the dispensing plunger to ascend within the syringe during the injection in a direction other than downward and toward the base of the device. When the plunger has completed the dispensing of the composition V and has voided the cavity 66, the patient or medical technician will be able to see the distal end of the plunger proximate to the filling end 352 of the cartridge, which serves as a convenient visual signal that the injection is nearing completion or has been completed. To assist in installing the separable attachment assembly 93 to the housing of the device, the lower surface of the housing base 12 can optionally be provided with a wide indent 97 surrounding the opening 95 in the inner base 91, and the separable base 92 can be provided with a raised flange 94 that registers with the indent 97, as shown in FIG. 20. Pressing upward on this area assists engaging the catch 89 onto the latch 96 of the separable base 92. A top plan view of a typical separable base assembly 93 is shown in FIG. 32, with a sectional view FIG. 33 taken through line 33-33, and detailed sectional views shown in FIGS. 34-35. The adhesive flap 112 extends outwardly from the periphery of the separable base 92, and is covered on its slower surface with the release paper 111. The adhesive flap 112 comprises a first film layer 114 that is affixed on its upper surface to cover the skin-facing surface of the separable base 92, and extends outward from the peripheral circumference of the base 92. The flap 112 has a PSA on its lower surface (not shown) for attachment to the skin. Flap 112 also comprises a second film layer 115 that is shaped as a ring with an inner circular edge 116 and an outer edge 117. The inner edge 116 extends inwardly and is affixed, typically with PSA, to the upper surface of the separable base 92 inboard of its circumferential edge. The second film layer 115 extends outwardly from the separable base 92, to overlap the first film layer 114 to its periphery, and there beyond to its outer edge 117. Typically, the adhesive flap layers 114 and 115 can be made of a flexible plastic film, and can be optionally vapor permeable or breathable. Alternatively, the second film layer 114 can be eliminated, and the underside of the separable base 92 can have a coating of PSA for direct-contact adhesion to the skin. Optionally a gauze bandage 113 can be secured to the underside of the separable base 92 over the opening 13, as shown in FIG. 35. In an alternative embodiment, the base separating means can comprise other mechanical securements, an adhesive securement, and a magnetic securement of the separable bas to the housing of the device. The other mechanical securements could include a mechanical “hook-and-loop” device that can include Velcro®, a hasp, a frangible joint, and a threaded joint). The magnetic securement can comprise a first magnetic member proximate the upwardly-facing surface of the separable base; and a second magnetic member proximate to the base portion and inside of the housing; wherein first magnet member and the second magnetic member have a magnetic attraction that secures the removable base to the housing, and wherein the removable base can be manually separated from the base portion of the housing by a manually-applied force that overcomes the force of the magnetic attraction. The separable base provides a means for obtaining a secure attachment of the housing of the device to the patient's skin, by providing for outwardly-extending adhesive flaps that are securely affixed to the relatively rigid structure of the separable base. In most circumstances, the separable base that remains behind on the skin of the patient is well tolerated by the patient, and can be removed at any time, since most vaccinations, particularly with very small needle diameters, leave little wounding of the skin The separable base 92 can also be removed for pre-injection inspection of the device, by fully depressing the release button 81, prior to installing the reservoir or the initiating needle insertion. The inner base 91, or a portion thereof, can be made of a transparent thermoplastic material to allow a visual inspection of the needle and the internal assembly prior to use. The separable base 92 can then be easily reaffixed. As shown in FIG. 28, after completing the injection, the syringe cartridge 18 can be removed from the attached housing 10, before the housing is removed from the separable base 92; or, the housing 10 with the syringe cartridge 18 attached can be removed from the separable base 92 as a unit, and then the syringe cartridge can be removed. The device can also comprise a means for preventing deployment of the needle through the opening in the base of the housing, particularly after the needle has been inside the skin and body of a person. A typical deployment prevention means for preventing needle deployment comprises a sliding or rotating plate disposed in the base that can moved between a first position where the needle opening in the base is not covered by the plate, and a second position wherein the plate covers the opening. In the embodiment illustrated in FIGS. 36-38, a rotating plate 131 is disposed in an annular recess 130 on the annular flange 94 of the inner base 91. The recess 130 and plate 131 have a center that is positioned off the centerline 100 passing through needle 40, though they overlap the needle opening 13 in the base 12. The plate 131 has an opening 136 disposed between the center of the plate 131 and its periphery. The plate 131 can rotate between a first deployment position shown in FIGS. 36 and 37 wherein the plate opening 136 registers with and leaves exposed the opening 13, and a second blocking position shown in FIG. 38 wherein the plate 131 covers the opening 13, and prevents deployment of the needle 40. The plate is movable between the first and second positions by a knob 132 that is attached to the plate by a stem 133. The stem is disposed within arc-shaped stem slot 134. The knob 132 moves along a knob recess 135 formed in the inner surface of the removable base 92, and that lies below the knob slot 134. The knob retains the plate in position, and can be manipulated by finger to move the plate between its first and second positions. Prior to injection, the technician can remove the removable base plate and manipulate the knob 132 to move the plate 131 to its deployment position. After the device is removed from the skin following the injection, and the device has been removed from the separable base 92, the exposed knob 132 can be manipulated to move the plate 131 to its blocking position. This physically closes the opening 13 to ensure that the needle 40 can not be redeployed accidentally and cause an undesired stick. In a further embodiment of the present invention, a device can have a plurality of injection needles and reservoirs disposed within the housing. The device can provide for injecting at least two injectable liquid compositions to a patient. FIGS. 29 and 30 show a top plan view and an elevation view of a device 1 for injecting at least two liquid compositions from separate reservoirs contained in the housing. As shown in FIG. 31, the device 1 can comprise a housing 10 and base 12 for two needle carriages 70a and 70b and two injection needles 40a and 40b, which can be configured to be separately and independently manipulated for insertion, injection and retraction, as described herein above. Alternatively, the two needle carriages and needles can be configured for simultaneous insertion, injection, and retraction using shared elements, including a shared, unitary dual-recess needle carriage, and a dual unitary pressurizing assembly. If only one injectable liquid composition will be administered, there is a potential for the patient, during the injection procedure, to pick at and possibly poke a finger though the seal 105 that is initially positioned over the cavity recess 71. To prevent this, the seal 105 can be affixed to a cylindrical member 106 that partly supports the underside of the seal 105 layer, as shown in FIG. 3A. Alternatively, the seal can be removed and replaced with a “dummy” plunger that has the upper appearance of the active syringe cartridge, but which fits securely in the opening in the housing above the carriage to block any attempt to depress the carriage. Another alternative embodiment of the device can comprise a means for selectively positioning and optionally securing the needle carriage 70 to respective positions that either prevent or enable its movement in the axial direction within the housing. This embodiment also is an alternative deployment prevention means. FIG. 42 illustrates this embodiment in the context of the dual-needle device. Each of the carriages 70a and 70b in FIG. 42 are shown in their first axial position, disposed within the carriage passageway 280 proximate the upper end 281. This is also the position in which the syringe cartridge 18 is inserted into or removed from the needle carriage 70. In the first axial position, the carriage can be rotated between a first rotational position wherein the carriage is restrained from movement in the axial direction, and a second rotational position wherein the carriage can move in the axial direction. Looking first at the carriage 70a on the left side of the device, which is in the axially restrained configuration, the vertically-oriented guide rib 19 projects outward from the cylindrical wall 14. The toe 79 of the carriage is positioned within a notch 119 formed in the guide rib 19, allowing the carriage to rotate, but preventing the carriage from moving downward axially so long as the toe 19 is disposed within notch 119. The cooperation of the toe 79 of the carriage disposed within the notch 119 of the guide rib 19 provides a means for restraining the movement of the carriage in the axial direction. The carriage 70b on the right side of the device is shown in the axially un-restrained configuration. In this configuration, the carriage 70b has been rotated (typically in the clockwise direction) to a position where the gap 179 in the toe 79 registers with the notch 119 in the guide rib 19, which allows the carriage 70b to move axially toward its second axial position proximate the base of the housing. As the carriage 70b first begins to descend, the gap 179 in the toe 79 slides along the guide rib 19, preventing the carriage from rotating after it has moved axially out of the first axial position. The carriage can also comprise a means for registering the rotation of the carriage in a direction that corresponds with either the axially restrained configuration (typically, counter-clockwise direction in the plan view shown in FIG. 29) or with the axially un-restricted configuration (typically clockwise). In the illustrated embodiment, a stop lug 180 is provided to assist registering the gap 179 with the notch 119, by limiting the rotation of the carriage. At the appropriate configuration, a stop lug 80 will engage the upper end 219 of the guide rib 19. The stop lug 180 is shown as a downwardly-extending projection from the outer wall 75 of the carriage 70, over a portion of the wall-contacting periphery of the carriage. As viewed in FIG. 42A, in the top-right of carriage 70b, a first end of the stop lug 180 is engaging the upper end 219 of the guide rib 19 from behind the guide rib, when the carriage is rotated in the clockwise direction. Conversely, as shown in FIG. 42, the stop lug 180 (which is not shown since it is out of the page in front of the section line), a second end of the stop lug 180 is engaging the upper end 219 of the guide rib 19 from in front the guide rib, when the carriage is rotated in the counter-clockwise direction. FIG. 44 shows an alternative embodiment of a device having a needle retracting means that comprises a pre-tensioned retracting spring that is associated with a separate member for retracting the needle. As illustrated in FIG. 44, the retracting means comprises an auxiliary retracting carriage 270. The retracting carriage 270 is configured for movement within the housing between a first secured position, shown in FIG. 44 where the retracting carriage is disposed proximate the base 91, and a second position where the retracting carriage is disposed proximate the upper end 281 of the carriage passageway 280. In the first position, the retracting spring 76 is in a fully compressed position, restrained by the retracting carriage 270, the toe 79 of which is restrained by the lower heels 86 of the release arms 80. As described above, when buttons 81 are depressed, heels 86 bias outwardly and out of engagement with toe 79, allowing the retracting spring 76 to move the unrestrained retracting carriage 270 toward and to its second position. It can be understood that depressing of the buttons 81 also bias the upper heels 286 to pivot or move outwardly. The force factor of the retracting spring 270 can be sufficient to cause the upper toe 279 of the retracting carriage 270 to pass over the upper heels 286 of the release arms 80 and into its second position proximate upper end 281 in the carriage passageway (not shown). Upon releasing of the pressing force upon buttons 81, the upper heels 286 return and are placed into an interference position that can prevent the retracting carriage 270 from being moved axially in a direction back toward its first position shown in FIG. 44. It can also be understood that the retracting carriage 270 can be moved from its second position proximate the upper end 281, to its first position, by sufficiently depressing buttons 81 to release the upper toe 279 from engagement with the upper heels 286, and manually pushing the retracting carriage 270 (and compressing the retracting spring 76) toward the base 91. It can also be understood that the needle carriage 70 can move within the carriage passageway 280 separately from the retracting carriage 270. The needle carriage 70 is typically positioned in its first position adjacent the upper end 281 of the carriage passageway 280 (such as shown in FIG. 22) for attachment of the syringe cartridge 18. In this position, the needle carriage can be restrained temporarily from axial movement (the needle carriage's axially restrained configuration, as described in the aforementioned embodiment and illustrated by the left-hand carriage 70a of FIG. 42). Alternatively, the needle carriage can be biased toward its first position by a second mechanical spring (not shown). At the same time, the retracting carriage 270 is typically in its pre-tensioned position shown in FIG. 44, adjacent the base 91. After the syringe cartridge 18 containing the liquid composition V has been secured in place to the needle carriage 70, also as shown in FIG. 22, the needle carriage bearing the injection needle 40 can be rotated from its axially restrained configuration into the axially un-restrained configuration (also described above and illustrated by the right-hand carriage 70b of FIG. 42). From its axially un-restrained configuration, the needle carriage 70 can be moved to its second position shown in FIG. 44 by manually pressing downward on the inserted syringe cartridge 18. The annular outer wall of the needle carriage 70 can have cut-out grooves 176 that align axially with the upper heels 286 when the carriage is in the axially un-restrained configuration, to allow free passage of the carriage past the upper heels 286. The needle carriage 70 can have an annular recess formed between the inner wall 174 and the outer annular wall 172. The respective carriages can become engaged and frictionally coupled together when the upper rim 272 of the retracting carriage 270 is nested within the annular recess of the needle carriage 70, but can be separated by hand. The frictional coupling of the needle carriage 70 to the restrained retracting carriage 270 assists in holding the inserted injection needle 40 within the injection site, as shown in FIG. 44. A further embodiment of the invention can comprise a means of indicating the extent of liquid composition dispensed from the reservoir. The indication means can comprise a visual means that allows personnel to actually view the remaining contents of the reservoir. An embodiment of a visual indication means can comprise a transparent section positioned in a portion of the housing adjacent the reservoir, to view the reservoir. Alternatively, the housing can comprise a door or panel that can be opened to permit inspection. Further, the reservoir can be provided with a corresponding transparent portion to permit the medical personnel to see the medication contained within the reservoir. The transparent portion can include a portion of the base or a portion of the housing, or both. The transparent portion can be a small area relative to the total surface area of the housing body, or can be a significant portion of the housing body surface. In a typical embodiment, the transparent portion is positioned on one side of the housing body that, when applied to the patient's arm, can face away for the patient's line of sight. This allows the medical technician to see through the transparent portion, but provides no indication to the patient, typically a small child, that the inside of the device contains something interesting that might arouse the patient's curiosity. The indication means can also comprise a signal means that signals the end or the approaching end of medicament dispensing. A signal means can comprise a mechanical or electrical switch that is activated by the plunger member as the last remaining contents of the reservoir is dispensed. The signal can be a flag, a pop-out tab, an illuminated light, or any other well known signal. Another embodiment of the invention can comprise a covering or disguise configured for attachment or placement over the injection device either to provide the device with a pleasurable impression, or to direct the patient's attention away from the device. The covering can be formed as a cartoon character, a zoo animal, or the like. In this way, much of the patient's fear that might be caused by the sight of the device can be alleviated. In another embodiment of the invention, the housing of the device can be colored coded or have a colored indicator or marking that identifies the particular type or quantity of medication contained within the reservoir. For example, for one certain medication the outer casing may be blue in color. The device can also display various warnings, such as a precaution to avoid needle stick and possible side effects to the medication. The device can also comprise a removable label comprising information about the liquid composition to be administered (such as the type of vaccine or medicament, the manufacturer and lot number, and volume), which can be placed into a medical record or patient chart. Another embodiment of the invention, shown in the figures, is an improved injection device for self-administering an injection that does not provide the patient with any convenient fingerhold to grasp the device for jostling or removing the device from the skin during the injection procedure. A preferred design of the device will include an outer surface that has not sharp edges or deep groove with which the patient can get a fingerhold. Preferably, the housing and the base are constructed of a thermoplastic material that has a non-grip or non-sticky surface, and is preferably a resilient material that can flex but not deform in shape. A matte finish on the outside surface can make the housing difficult to grasp, except when properly grasped by a medical technician by its release buttons. Typically, the indentures and grooves in the housing, and including the base, have a breadth not greater than 3 mm, more typically not greater than 1 mm. Typically, external edges can be rounded, maintaining an edge radius of about at least 1 mm, more typically of about at least 3 mm. While specific embodiments of the apparatus and method of the present invention have been described, it will be apparent to those skilled in the art that various modifications thereto can be made without departing from the spirit and scope of the present invention as defined in the appended claims.

<SOH> BACKGROUND OF THE INVENTION <EOH>The present invention relates to the injection of vaccines and other medication and, more particularly, to an injection device that can be used in a method for administering vaccine injections painlessly for a patient. Conventional medical injection devices for injecting medication into the muscle or tissue of a patient typically comprise some form of a manual hypodermic syringe. Generally speaking, a hypodermic syringe consists of a cylindrical barrel having a chamber that provides a reservoir for a liquid medication, a distal end adapted to be connected to a hollow hypodermic needle and for placing one end of the needle into flow communication with the medication contained within the chamber, and a proximal end adapted for receiving a stopper and plunger assembly. The stopper and plunger assembly includes a stopper effective for moving along the barrel chamber and an elongated plunger effective for causing movement of the stopper. The needle of the hypodermic syringe is manually inserted into the patient through the skin. The stopper is moved along the barrel chamber by applying axial force to the plunger, thereby forcing the liquid medication out of the barrel chamber, through the hypodermic needle and into the muscle or tissue of the patient. Receiving an injection by such a conventional device can be a very traumatic experience, particularly for a child. The child's fears, and that of the child's parent, can become a significant medical problem if it leads to the child not receiving a required vaccination. These fears are predominately caused by pain that is associated with injections given by conventional injection devices and methods. We have found that the pain associated with an injection is related to the size of the needle and the flow rate at which the medication is injected. It has been found that the amount of pain or discomfort experienced by a patient increases as the outside diameter of the needle increases. It is believed that high flow rates of medication injection (e.g., about 0.5-2 ml per second) into the patient can tear internal tissue and cause pain. The tearing of tissue is caused by the build-up of excessive pressure within the tissue when the surrounding tissue is unable to quickly absorb the injected medication. While the injection of a medication at a relatively slow flow rate is more comfortable for the patient, the increased amount of time the syringe remains in the hand of the medical personnel can make the technique tiring for such personnel as well as the patient. In addition, small vibrations or disturbances of the needle caused by movement of the medical personnel or the patient can result in pain to the patient. It is known that the fluctuation of flow rate of the injection of medication being delivered by a hand-held syringe can vary greatly. It is extremely difficult, if not impossible, to deliver a steady, very slow flow of medication from a hand-operated syringe (the human thumb depressing the syringe plunger) over an extended amount of time. It has also been found that the sight of the hypodermic needle by itself is often enough to cause many patients to become anxious and tense. This reaction in turn may cause the patient's muscles to become tight and hard, making needle penetration even more difficult and painful. A number of methods and devices have been developed for reducing or eliminating the pain and discomfort associated with medical injections. One such method includes the application of a topical anesthetic to the injection site on the patient's skin prior to the injection, which itself can be painful. While this method has reduced some of the discomfort associated with injections, the topical anesthetic does not substantially penetrate the skin into the deeper skin and muscle tissue, and can take significant time (up to 45 minutes) to show effects. Substantial pain and discomfort with intramuscular injections can remain. Another technique for reducing the pain and discomfort associated with medical injections includes the step of injecting an anesthetic at the site of the injection using a fine gauge needle, then inserting the larger medication hypodermic needle through the anesthetized skin to inject the medication at a constant and slow flow rate intramuscularly at the desired depth. Unfortunately, injecting an anesthetic into a patient can be painful, and is not always desirable, and the technique is relatively expensive and impractical for many routine injection procedures. In addition to reducing pain or discomfort to the patient, safety has also become a principal concern to medical personnel. Special precautions must be taken to avoid accidental needle sticks that could place a user at serious risk because of the danger from fluid borne pathogens. Despite the taking of special precautions, there still remains the possibility of an accidental needle contact and attendant injury. Accordingly, medical injection devices should operate to minimize the possibility of injury caused by accidental needle sticks. In recent years, increased emphasis has been placed on establishing treatment protocols aimed at providing a patient as well as medical personnel with greater freedom of movement. To this end, there is a great deal of interest in the development of light weight and easy-to-use portable injection devices. Accordingly, a need exists for substantially painless method and an apparatus for performing the method of injecting medication into a patient that does not require the use of an anesthetic, that does not require the medical personnel to spend a substantial amount of time performing a particular procedure, that is relatively simple, portable and inexpensive to perform and operate, that permits the patient a relatively high degree of movement during the injection, and that provides a relatively high degree of safety for both the medical personnel and for the patient.

<SOH> SUMMARY OF THE INVENTION <EOH>The present invention relates to an injection device that is manually-powered and configured for self-administering painlessly an injectable liquid composition, such as a vaccine or medicament. The device can be used in a method for providing a substantially painless injection of the injectable liquid composition to a patient that does not require the use of an anesthetic, that does not require the medical personnel to spend a substantial amount of time performing the injection procedure, that is relatively simple and inexpensive to prepare and operate, and that provides a relatively high degree of safety for both the medical personnel and for the patient. The present invention further relates to a manually-powered injection device for self-administering painlessly an inter-muscular injection of an injectable liquid composition contained within a reservoir, comprising a) a housing having a base for semi-permanent attachment to the skin of a patient, b) an injection needle disposed substantially perpendicular to the base and within the housing, the needle having an injection end, and configured for axial movement manually between a first position wherein the injection end is within the housing and a second position wherein the injection end extends outwardly from the base to a distance sufficient for intramuscular insertion thereof, the injection needle having an outside diameter greater than 0.10 mm and less than about 0.38 mm, c) a means for retaining a reservoir for containing an injectable liquid composition, d) a means for providing liquid communication between the retained reservoir and the injection needle, e) a means for injecting the injectable liquid composition from the retained reservoir through the needle. The present invention also relates to a manually-powered injection device for self-administering painlessly an inter-muscular injection of an injectable liquid composition, comprising a) a housing having a base for semi-permanent attachment to the skin of a patient, b) an injection needle disposed substantially perpendicular to the base and within the housing, the needle having an injection end, and configured for axial movement manually between a first position wherein the injection end is within the housing and a second position wherein the injection end extends outwardly from the base to a distance sufficient for intramuscular insertion thereof, the injection needle having an outside diameter greater than 0.10 mm and less than about 0.38 mm, c) a reservoir for containing the injectable liquid composition, d) a means for liquid communication between the reservoir and the injection needle, and e) a means for injecting the injectable liquid composition from the reservoir to the needle. The present invention also provides an improved cartridge for use in a self-administering injection device, that comprises separate and spaced-apart filling and dispensing ports, and which allows a dispensing plunger to ascend within the cartridge during the injection in a direction toward the filling port. This can provide a visual signal when the distal end of the plunger approaches the filling end of the cartridge, at the completion of the liquid composition injection. In typical embodiments of the present invention, the needle is affixed to a needle carriage that is configured for axial movement between a first position associated with the first position of the injection needle, and a second position associated with the second position of the injection needle, in response to the manual force applied by the person. Upon manual insertion of the needle, a needle insertion securement secures the carriage in the second position the liquid composition is injected. The device is typically employs a manually-powered spring that is compressed during the manual needle insertion, which exerts pressure upon the injectable liquid composition within the retained reservoir. The needle carriage and the reservoir comprise cooperating threads that can engage and retain the reservoir within the carriage, and which can cause penetration of a penetrable membrane in the reservoir by the inlet end of the injection needle to establish liquid communication there between. At the end of the injection cycle, a needle retracting means can be activated, typically manually, to retract the injection needle, whereby the injection end of the needle is retracted from its second position in the body to a third position wherein the injection end of the needle is within the housing. The needle retracting means can employ a disengagement means configured to disengage the needle insertion securement from the needle carriage, and a power means configured to bias the needle carriage to the third position. An implement, such as a plunger or stem, can be used in place of the finger or hand to apply the manual insertion force to the needle carriage. The device can also comprises a separable base, a base securement means configured for separable securement of the separable base to the housing, and a base separation means configured for separation of the separable base from the housing, wherein the separable base comprising an adhesive for attachment thereof to the skin of the patient.

20070621

20100302

20071220

81009.0

A61M524

PRICE, NATHAN R

INJECTION DEVICE FOR ADMINISTERING A VACCINE

SMALL

ACCEPTED

A61M

ACCEPTED

Network Architecture

A system and method for self-organizing, reliable, multiple path data flow transmission of messages data on a network uses queues to transmit messages between end-user modules (EUMs) on nodes on the network. The EUMs include the end user applications with which queues are associated. A network communications manager (NCM) resident on every node manages all transmission of messages between nodes. The NCM on a given node only has knowledge of nodes that are neighbor nodes to that given node, but has knowledge of all queues associated with all EUMs. Messages are divided into EUM messages, which are placed in queues by the NCM on each node, and system messages, which are not placed in queues but are used by the NCM to determine when and where, i.e. to which neighbor node, messages may be sent. The NCM on each node chooses a neighbor node as a target node for sending EUM messages for each queue, based on the best node latency and at capacity status of each neighbor node. These target nodes are used to provide potential routes to queues and multiple path data flow for queues that carry EUM data messages for user applications. These target nodes are constantly updated to provide the best paths on an adaptive basis and to ensure that all paths are valid, improving network reliability. When choosing when to send data to a target node, each node uses tokens for flow control to ensure that target nodes do not become overloaded. The node also compares node latencies for multiple target nodes to ensure that the lowest node latency target node is chosen. By using neighbor nodes as target nodes, node latency, and at capacity information for determining when and where to send data, there is no need to maintain any global knowledge of all paths in the network. Further, the constant updating of target nodes ensures that the network maintains optimal and valid paths for messages, thus ensuring efficiency and reliability. Finally, the constant updating of target nodes ensures that reliability and efficiency are provided on an adaptive, self-organizing basis.

1-18. (canceled) 19. A self-organizing network comprising: (a) a plurality of nodes; (b) at least one link interconnecting neighbouring ones of said nodes; (c) each of said nodes being operable to maintain information about each of said other nodes that is within a first portion of said nodes, said information including: (i) a first identity of another one of said nodes within said first portion; (ii) for each first identity, a second identity representing a neighbouring node that is a desired step to reach the said another one of said nodes respective to said first identity; (d) each of said nodes being operable to maintain a third identity representing a neighbouring node that is a desired step to send a request for information about said nodes in a second portion of said nodes that is not included in said first portion. 20. The network according to claim 19 wherein said third identity is determined based on which of said neighbouring nodes most frequently appears in each said second identity. 21. The network of claim 19 wherein each of said nodes is operable to exchange said information with its neighbouring nodes. 22. The network of claim 19 wherein said at least one link has a set of service characteristics such that any path between two of said nodes has a cumulative set of service characteristics. 23. The network of claim 22 wherein said information includes said cumulative set; and said desired step associated with said second identity is based on which of said paths has a desired cumulative set of service characteristics. 24. The network of claim 22 wherein said service characteristics include at least one of bandwidth, latency and bit error rate. 25. The network of claim 19 wherein said nodes are at least one of computers, telephones, sensors, personal digital assistants. 26. The network of claim 19 wherein said at least one link is based on a wireless connection. 27. The network of claim 19 wherein a network core is formed between neighbouring nodes that determine each other is a desired step to locate said nodes within said second portion. 28. The network of claim 27 wherein each said node is operable to deliver instructions to other nodes between said core and itself to maintain information about itself. 29. The network of claim 27 wherein said information includes, for each said first identity, a value representing a distance-to-data marked stream for said node associated with said first identity. 30. The network of claim 29 wherein nodes associated with said first identity are ranked in an ascending order increasing according to said distance and said instructions are delivered to those nodes according to said rank. 31. The network of claim 19 comprising at least 2,000 nodes interconnected by a plurality of links. 32. The network of claim 19 comprising at least 5,000 nodes interconnected by a plurality of links. 33. The network of claim 19 comprising at least 10,000 nodes interconnected by a plurality of links. 34. The network of claim 19 comprising at least 100,000 nodes interconnected by a plurality of links. 35. A node for use in a self-organizing network having a plurality of other nodes and at least one link interconnecting neighbouring ones of said nodes; said node comprising: (a) a computing apparatus operable to maintain information about each of said other nodes that is within a first portion of all of said other nodes, said information including: (i) a first identity of another one of said nodes within said first portion; (ii) for each said first identity, a second identity representing a neighbouring node that is a desired step to reach the said another one of said nodes respective to said first identity; said computing apparatus further operable to maintain a third identity representing a neighbouring node that is a desired step to send a request for information about said nodes in a second portion of said nodes that are not included in said first portion. 36. A computer readable medium for storing a set of programming instructions for execution by, or on behalf of, a node forming part of a self-organizing network having a plurality of other nodes and at least one link interconnecting neighbouring ones of said nodes; said programming instructions for causing a computing apparatus within said node to maintain information about each of said other nodes that are within a first portion of all of said other nodes, said information including: (a) a first identity of another one of said nodes within said first portion; (i) for each said first identity, a second identity representing a neighbouring node that is a desired step to reach the said another one of said nodes respective to said first identity; said programming instructions for further causing said computing apparatus to maintain a third identity representing a neighbouring node that is a desired step to send a request for information about said nodes in a second portion of said nodes that are not included in said first portion. 37. The computer readable medium according to claim 36 wherein said third identity is determined based on which of said neighbouring nodes most frequently appears in each said second identity. 38. The computer readable medium of claim 36 wherein each of said nodes is operable to exchange said information with its neighbouring nodes. 39. The computer readable medium of claim 36 wherein said at least one link has a set of service characteristics such that any path between two of said nodes has a cumulative set of service characteristics. 40. The computer readable medium of claim 39 wherein said information includes said cumulative set; and said desired step associated with said second identity is based on which of said paths has a desired cumulative set of service characteristics. 41. The computer readable medium of claim 39 wherein said service characteristics include bandwidth. 42. The computer readable medium of claim 39 wherein said service characteristics include latency. 43. The computer readable medium of claim 39 wherein said service characteristics include bit error rate. 44. The computer readable medium of claim 36 wherein said nodes are computers. 45. The computer readable medium of claim 36 wherein said nodes are telephones. 46. The computer readable medium of claim 36 wherein said nodes are sensors. 47. The computer readable medium of claim 36 wherein said nodes are personal digital assistants. 48. The computer readable medium of claim 36 wherein said at least one link is based on wireless connections. 49. The computer readable medium of claim 36 wherein a network core is formed between neighbouring nodes that determine each other is a desired step to locate said nodes within said second portion. 50. The computer readable medium of claim 49 wherein each said node is operable to deliver instructions to other nodes between said core and itself to maintain information about itself. 51. The computer readable medium of claim 49 wherein said information includes, for each said first identity, a value representing a distance-to-data marked stream for said node associated with said first identity. 52. The computer readable medium of claim 51 wherein nodes associated with said first identity are ranked in an ascending order increasing according to said distance and said instructions are delivered to those nodes according to said rank. 53. The computer readable medium of claim 36 comprising at least 2,000 nodes interconnected by a plurality of links. 54. The computer readable medium of claim 36 comprising at least 5,000 nodes interconnected by a plurality of links. 55. The computer readable medium of claim 36 comprising at least 10,000 nodes interconnected by a plurality of links. 56. The computer readable medium of claim 36 comprising at least 100,000 nodes interconnected by a plurality of links. 57. A computer readable medium for storing a set of programming instructions for execution by, or on behalf of, a first node on a hierarchical network having a plurality of nodes and at least one link interconnecting each of said nodes, said instructions causing a computing apparatus to select and maintain information about a parent node, said parent node comprising a neighbouring node in said network that is above said first node in respect to the hierarchy of said network or equal to said first node when there is no node that is above said first node. 58. A computer readable medium as claimed in claim 57 wherein said instructions cause said computer apparatus to select among a plurality of parent nodes based on which parent node is the next best step to a predetermined set of other nodes on said network. 59. A computer readable medium as claimed in claim 57 wherein said instructions cause said computer apparatus to select and maintain information about a plurality of parent nodes in said network to facilitate formation of different hierarchies within the same network. 60. A computer readable medium as claimed in claim 57 wherein said instructions cause said computer apparatus to push information from said first node to a subset of neighbouring nodes including at least one of said selected parent nodes. 61. A computer readable medium as claimed in claim 57 wherein said instructions cause said computer apparatus to push information received from a neighbouring node to at least one of said selected parent nodes. 62. A computer readable medium as claimed in claim 57 wherein said instructions cause said computer apparatus to push information to a node that has selected said first node as a parent node. 63. A computer readable medium for storing a set of programming instructions for execution by, or on behalf of, a first node on a self-organizing network having a plurality of nodes and at least one link interconnecting said nodes, said instructions causing a computing apparatus to select and remove information about one or more missing nodes in said network by delaying the sending of predetermined classes of updates to said network. 64. A computer readable medium as claimed in claim 63 where a node update is delayed before being sent to a neighbor node if an update about said node has not been previously sent to said neighbor. 65. A computer readable medium as claimed in claim 63 where a node update is delayed before being sent to a neighbor node if the previous update about said node sent to said neighbor belongs to a predetermined class of updates. 66. A computer readable medium as claimed in claim 65 where said predetermined class is a node update where said update indicates that no route is possible via said sending node. 67. A computer readable medium for storing a set of programming instructions for execution by, or on behalf of, a first node on a self-organizing network having a plurality of nodes and at least one link interconnecting each of said nodes, said instructions causing a computing apparatus to select and remove information about one or more missing nodes in said network by sending predetermined classes of updates to said network when a predetermined internal state is reached. 68. A computer readable medium as claimed in claim 67 where said predetermined internal state is where the hop cost to said node increases more then a predetermined amount. 69. A computer readable medium as claimed in claim 67 where said predetermined internal state is where the importance value associated with said node increases more then a predetermined amount. 70. A computer readable medium as claimed in claim 67 where said predetermined class indicates that no route is possible to said node via said sending node. 71. A computer readable medium for storing a set of programming instructions for execution by, or on behalf of, a first node on a self-organizing network having a plurality of nodes and at least one link interconnecting each of said nodes, said instructions causing a computing apparatus to identify the route between a source node and a destination node. 72. A computer readable medium as claimed in claim 71 wherein said instructions further cause the computing apparatus to identify the proximity of said first node to the identified route between said source node and said destination node. 73. A computer readable medium as claimed in claim 71 wherein said node on the identified route between a source node and destination node will set the importance value of said destination node to a predefined value. 74. A computer readable medium as claimed in claim 73 where the predefined value is the highest importance value possible. 75. A computer readable medium as claimed in claim 71 wherein said instructions further cause the computing apparatus to send route updates about said destination node on a relatively more frequent basis the closer that said first node is to the route between said source node and said destination node. 76. A computer readable medium for storing a set of programming instructions for execution by, or on behalf of, a first node on a self-organizing network having a plurality of nodes and at least one link interconnecting each of said nodes, said instructions causing a computing apparatus to assign an importance value to updates that are to be sent over said network. 77. A computer readable medium as claimed in claim 76 wherein said importance value is determined by how close said first node is to a specified data path or specified structure in the network. 78. A computer readable medium as claimed in claim 76 wherein said instructions further cause the computing apparatus to assign a hop cost value to updates that are to be sent over said network. 79. A computer readable medium as claimed in claim 78 wherein said hop cost value for a particular destination node is determined by an accumulation of service characteristics on the route from said node to said destination node. 80. A computer readable medium as claimed in claim 76 wherein said instructions further cause the computing apparatus to communicate to other nodes that said first node wishes only to receive updates that have or exceed a predetermined importance value. 81. A computer readable medium as claimed in claim 76 wherein said instructions further cause the computing apparatus to communicate to other nodes that said first node wishes only to receive a predetermined number of updates with the highest importance values. 82. A computer readable medium for storing a set of programming instructions for execution by, or on behalf of, a first node on a self-organizing network having a plurality of nodes and at least one link interconnecting each of said nodes, said instructions causing a computing apparatus to attach a specific node number identifying said first node to data packets being sent by said first node. 83. A computer readable medium as claimed in claim 82 wherein said instructions further cause the computing apparatus to perform an O(1) lookup for packet routing when said first node receives a data packet having a specific node number identifying another node. 84. A computer readable medium as claimed in claim 36, said instructions causing a computing apparatus to assign a value to said first node that can be taken into account during the selection of parent nodes in said network. 85. A computer readable medium for storing a set of programming instructions for execution by, or on behalf of, a first node on a self-organizing network having a plurality of nodes and at least one link interconnecting each of said nodes, said instructions causing a computing apparatus to forward messages from a source node to a destination node via neighbors depending on the latency to the destination node via said neighbors. 86. A computer readable medium as claimed in claim 85 wherein the latency of the internal message queue of messages for a destination node is used to decide which neighbor messages for said destination node should be sent to. 87. A computer readable medium as claimed in claim 86 wherein messages for a destination node are sent to a neighbor node if the latency to said destination node from said neighbor node is equal or less then the latency of the message queue for messages being sent to said destination node. 88. A computer readable medium as claimed in claim 85 wherein messages for a destination node are not sent to a neighbor node when the neighbor node is in a specified state regarding messages for said destination node. 89. A computer readable medium as claimed in claim 88 wherein messages for a destination node are not sent to a neighbor node when the neighbor node can not process an increased volume of messages for said destination node. 90. A computer readable medium for storing a set of programming instructions for execution on a first node, where said first node forms part of a self-organizing network having a plurality of other nodes executing similar sets of said programming instructions and at least one link interconnecting neighbouring ones of said nodes; said programming instructions causing said first node to: (a) determine the identity of a parent node, wherein said parent node is a neighboring node to said first node that has one or more desired characteristics; (b) deliver instructions to a neighboring node from said first node that will cause said neighboring node to deliver instructions to its determined parent node; and (c) deliver instructions in response to said neighboring node that has delivered instruction to said node to deliver instructions to its determined parent node. 91. A computer readable medium as claimed in claim 90 wherein said one or more desired characteristics include the characteristic of how many nodes in said network have a preferred route through said neighbor node. 92. A computer readable medium as claimed in claim 91 wherein said programming instructions further cause said first node to determine a value attached to at least one of said other nodes to cause said first node to place more significance to the selection of said neighboring node as a best next step to reach said node. 93. A device utilizing the instructions stored by the computer readable medium as claimed in claim 36. 94. A device as claimed in claim 93 wherein said device comprises one of: a router, a cell phone, a pda, a utility meter, a vehicle, an aircraft, a sensor, a munition, a satellite, a computer or any other device capable of utilizing said instructions stored in said computer readable medium. 95. A self-organizing network comprising: (a) a plurality of interconnected nodes, wherein neighbouring nodes are interconnected by at least one link; (b) each of said nodes being operable to maintain information about at least one of said other nodes, said information including in respect to a representative first node: (i) a first identity identifying a second node that is a best neighbour to said first node according to one or more pre-determined factors; (ii) for each first identity, a second identity identifying a third node that is a next best neighbour to said first node according to one or more pre-determined factors. 96. A computer implemented process for spreading network knowledge within a network having a plurality of nodes, each said node being linked to a neighbouring node by at least one link, said process comprising the steps of: (a) each node determining the presence of at least one neighbouring node in said network; (b) each said node exchanging information with neighbouring nodes in said network concerning the presence of said neighbouring nodes; (c) each said node updating its information concerning neighbouring nodes in said network based on said information received from said neighbouring nodes; and (d) repeating said steps at desired intervals. 97. A computer implemented process for delivering payload data from an originating node to a destination node in a network having a plurality of nodes, each said node being linked to a neighbouring node by at least one link, and at least some of said nodes having information concerning certain service characteristics for said neighbouring nodes, said process comprising the steps of: (a) identifying one or more desired service characteristics associated with payload data intended for delivery in said network; and (b) selecting a preferred delivery path among said nodes in said network for said payload data based upon said desired service characteristics and said service characteristic information. 98. A process as claimed in claim 97 wherein said service characteristics comprise at least one of bandwidth, cost, speed and bit error rate. 99. A computer implemented process for spreading instructions that control the spread network knowledge within a network having a plurality of nodes, each said node being linked to a neighbouring node by at least one link, said process comprising the steps of: (a) each node establishing a connection with one or more neighboring nodes; (b) each node determining the identity of a parent node, wherein said parent node is a neighboring node to said first node that has one or more desired characteristics; (c) each node that receives particular instructions from a neighboring node delivering instructions to its determined parent node; (d) each node that receives particular instructions from a parent node in response to instructions it sent to said parent node sending instructions to said neighbor node that sent said node instructions that caused said node to send instructions to said parent node; and (e) each node repeating said steps at desired intervals. 100. A computer implemented process for increasing the frequency that a node sends updates about a destination node the closer said node is to a data path to said destination node, said process comprising the steps of: (a) each node establishing a connection with one or more neighboring nodes; (b) each first node determining a rank to all nodes based on its proximity to said node or a data path heading towards said node; (c) each first node sending node updates to neighbor nodes more frequently based on rank of said nodes; and (d) each node repeating said steps at desired intervals. 101. A computer implemented process for removing information about a node after said node is removed from a network, said process comprising the steps of: (a) each node delaying the sending of a node update to a neighbor if previous update about said node indicated that there was no route to said node through said sending node; (b) each node delaying the sending of a node update to a neighbor if no previous update about said node had been sent by said sending node to said neighbor node; and (c) each node repeating said steps at desired intervals. 102. A computer implemented process for removing information about a node after said node is removed from a network, said process comprising the steps of: (a) each node sending an update about some node in the network indicating that said sending node has no route to said node in the network if said sending node determines that the cumulative service characteristics to reach said network node have reached a specified state; and (b) each node repeating said step at desired intervals. 103. A computer implemented process for ranking importance of node updates based on the proximity to structures that affect said nodes, said process comprising the steps of: (a) each node establishing a connection with one or more neighboring nodes; (b) each node ranking all nodes that it has stored information on based on said nodes proximity to structures that affect said nodes; (c) each node sending updates about said nodes to said neighbor nodes on a relatively more frequent basis the higher the rank of said nodes; and (d) each node repeating said steps at desired intervals. 104. A computer implemented process for sending data to destination nodes via neighbor nodes based on the latency provided by said neighbor nodes to said destination nodes, said process comprising steps of: (a) each node establishing a connection with one or more neighboring nodes; (b) each node forwarding messages for a destination node to a neighbor node that provides a latency value that is less or equal to the latency of the queue of messages stored on said node for said destination node; and (c) each node repeating said steps at desired intervals. 105. A computer implemented process for quickly routing data from node to node by using locally assigned numbers that represent the names of nodes in the network, said process comprising steps of: (a) each node establishing a connection with one or more neighboring nodes; (b) each node using an internal number to represent the names of nodes that it stores information on; (c) each node determining which neighbor node to send data packet for said destination node by using its internal number to efficiently look up the preferred neighbor; (d) each node before sending a data packet for a destination node to a neighbor node sending a message to said neighbor node that allows said neighbor node to determine which internal number represents the name of said destination node; (e) each node sending a data packet for a destination node to a neighbor node with said nodes internal number representing the name of said destination node attached to said data packet; (f) each node upon receipt of said internal number performing a lookup to translate said neighbors internal number into said nodes internal number; and (g) each node repeating said steps at desired intervals. 106. A computer implemented process for limiting the number of different nodes that a neighbor node is sent updates for, said process comprising the steps of: (a) each node establishing a connection with one or more neighboring nodes; (b) each node ranking all nodes that it has stored information on based on said nodes proximity to structures that affect said nodes; (c) each node telling its neighbors the maximum number of nodes it wants to be sent updates for; (d) each neighbor node sending said node its highest ranked nodes up to the maximum count requested by said node; and (e) each node repeating said steps at desired intervals.

PRIORITY CLAIMS The present application claims priority from Canadian Patent Application No. 2,457,909, filed Feb. 16, 2004, U.S. Provisional Patent Application No. 60/544,341, filed Feb. 17, 2004, Canadian Patent Application No. 2,464,274, filed Apr. 20, 2004, Canadian Patent Application No. 2,467,063, filed May 17, 2004, Canadian Patent Application No. 2,471,929, filed Jun. 22, 2004, Canadian Patent Application No. 2,476,928, filed Aug. 16, 2004 and Canadian Patent Applicant No. 2,479,485, filed Sep. 20, 2004, the contents of all of which are incorporated herein by reference. FIELD OF THE INVENTION The present invention relates generally to electronic, telecommunication and computing devices that communicate with each other and more particularly to a network architecture therefor. BACKGROUND OF THE INVENTION Networked devices are now an extremely important aspect of our social fabric. The public switched telephone network (“PSTN”) is perhaps the first example of a ubiquitous network of telecommunication devices that changed the way people interact. Now, mobile telephone networks, the Internet, local area networks (“LAN”), wide area networks (“WAN”), voice over internet protocol (“VOIP”) networks, are widely deployed and growing. It is trite to say that each of these devices need to be able to reach each other in order to fulfill networking functions. With the PSTN, a system of telephone numbers is employed, including country codes, area codes, local exchanges, etc. At least in North America, the explosion of telephonic devices has stretched the standard ten digit number scheme. With the Internet, the Internet Protocol Version 4 (“IPV4”) promulgates a system of Internet Protocol (“IP”) addresses to identify points on the Internet, and thus each networked device has an address making it reachable on the Internet. Due at least in part to the limited length of the IPV4 address field, IP addresses can bear little geographic relationship to their physical location. As a result, routers and routing tables throughout the Internet are extremely bloated, increasing complexity in traffic routing and increasing network latency. IPV6 offers potential relief addresses, but the upgrade to IPV6 is expected to be slow. In very general terms, many prior art network architectures rely on routing devices to maintain addresses and locations of the devices throughout the network. Such routing devices are essentially traffic cops, routing traffic along appropriate pathways. Such architectures become clumsy and awkward as the networks grow. Various “router-less” network architectures have been proposed. Some of these architectures are referred to as peer-to-peer networks, while others are referred to as ad-hoc networks. Regardless, these prior art architectures also tend to suffer from scaling and/or other limitations. One attempt to improve network architectures is Ad Hoc On Demand Distance Vector (“AODV”). AODV is a reactive protocol that uses a broadcast flood in order to establish a new connection or fix a broken connection. AODV is described in detail in the Internet Engineering Task Force (“IETF”) document found at http://www.ietf.org/rfc/rfc3561.txt. While AODV has the advantage of being able to easily organize nodes into an ad-hoc network one of the problems it has is that the maximum network size is extremely limited. Another attempt to improve network architectures is ‘Destination Sequenced Distance Vector’ (“DSDV”). DSDV is a proactive protocol that uses a constant flood of updates to create and maintain routes to and from all nodes in the network. A detailed description of DSDV is found at http://citeseer.ist.psu.edu/cache/papers/cs/2258/http:zSzzSzwww.srvloc.orgzSzcharliepzSz txtzSzsigcomm94zSzpaper.pdf/perkins94highly.pdf or http://citeseer.ist.psu.edu/perkins94highly.html. While DSDV has the advantage of providing loop free routing it has the disadvantage of a only working in small networks. In large networks the control traffic easily exceeds the available bandwidth. Another attempt to improve network architectures is ‘Optimized Link State Routing’ (“OLSR”). OLSR is a proactive protocol that attempts to build knowledge of the network topology. A detailed description of OLSR can be found in this IETF draft http://hipercom.inria.fr/olsr/draft-ietf-manet-olsr-11.txt. While OLSR has the advantage of being a more efficient link state protocol it is still unable to support larger networks. Another attempt to improve network architectures is ‘Open Shortest Path First’ (“OSPF”). OSPF is a proactive link state protocol that is used by some internet core routers. A detailed description of OSPF can be found in this IETF draft http://www.ietf.org/rfc/rfc1247.txt. While OSPF allows core internet routers to route around failure is has limitations on the size of networks it is able to support. Despite the differences between AODV, DSDV, OLSR and OSPF they all share some, of the same problems—e.g. the difficulty of scaling past a few hundred nodes. This limitation occurs because as the network grows, the amount of control traffic required grows much faster. Rapidly, the amount of control traffic needed will exceed the capacity of the network In general, prior art network architectures do not provide the good scalability, nor do they provide the ability to allow low capacity devices to fully interact with the larger network, and in mobile environments, prior art architectures do not always provide seamless mobility. SUMMARY OF THE INVENTION It is an object of the present invention to provide a novel system and method for networking that obviates or mitigates at least one of the above-identified disadvantages of the prior art. A first aspect of the invention provides a network that comprises a plurality of nodes and a plurality of links interconnecting neighbouring ones of the nodes. Each of the nodes are operable to maintain information about each of the nodes that are within first portion of the nodes. The information includes: a first identity of another one of the nodes within the first portion; and for each first identity, a second identity representing a neighbouring node that is a desired step to reach the another one of the nodes respective to the first identity. Each of the nodes are operable to determine a neighbouring node that is a desired step to locate the nodes in a second portion of the nodes that are not included in the first portion. In a particular implementation of the first aspect, the determination is based on which of the neighbouring nodes most frequently appears in each second identity. In a particular implementation of the first aspect, each of the nodes is operable to exchange the information with its neighbouring nodes. In a particular implementation of the first aspect, each link has a set of service characteristics such that any path between two of the nodes has a cumulative set of service characteristics; and wherein the desired step is based on which of the paths has a desired cumulative set of service characteristics. In a particular implementation of the first aspect, the service characteristics include at least one of bandwidth, latency and bit error rate. In a particular implementation of the first aspect, the nodes are at least one of computers, telephones, sensors, personal digital assistants. In a particular implementation of the first aspect, the links are based on at least one of wired and wireless connections. In a particular implementation of the first aspect, a network core is formed between neighbouring nodes that determine each other's desired step to reach the nodes within the second portion. In a particular implementation of the first aspect, each node is operable to instruct other nodes between the core and the node to maintain information about the node. In a particular implementation of the first aspect, each node is operable to request information about the nodes within the second portion; each node being operable to make the request to the other nodes between the core and the node. One advantage of the present invention over the prior art is that the network architecture taught herein allows for large scale self-organizing networks. This feature is enabled, for certain embodiments, because very few nodes in the network need actually have knowledge of the entire network. Collectively, all nodes in the network have knowledge of the entire network, and nodes that are unaware of other nodes, but which need find such other nodes, are provided with means of locating those other nodes by seeking such knowledge from other nodes in the network having relevant knowledge. For these and other reasons, the present invention is a novel self-organizing network architecture that enables for substantially larger self-organizing networks than prior art self-organizing network architecture. Thus, a second aspect of the invention provides a self-organizing network comprising at least 2,000 nodes interconnected by a plurality of links. A third aspect of the invention provides a self-organizing network comprising at least 5,000 nodes interconnected by a plurality of links. A fourth aspect of the invention provides a self-organizing network comprising at least 10,000 nodes interconnected by a plurality of links. A fifth aspect of the invention provides a self-organizing network comprising at least 100,000 nodes interconnected by a plurality of links. BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described by way of example only, and with reference to the accompanying drawings, in which: FIG. 1 is a schematic representation of a network in accordance with an embodiment of the invention; FIG. 2 shows a flow-chart depicting a method of spreading network knowledge in accordance with an embodiment of the invention; FIG. 3 is a schematic representation of a network depicting a performance of a step of the method of FIG. 2, in accordance with an embodiment of the invention; FIG. 4 is a schematic representation of a network depicting a performance of a step of the method of FIG. 2, in accordance with an embodiment of the invention; FIG. 5 is a schematic representation of a network depicting a performance of a step of the method of FIG. 2, in accordance with an embodiment of the invention; FIG. 6 is a schematic representation of a network depicting a performance of a step of the method of FIG. 2, in accordance with an embodiment of the invention; FIG. 7 is a schematic representation of a network depicting a performance of a step of the method of FIG. 2, in accordance with an embodiment of the invention; FIG. 8 is a schematic representation of a network depicting a performance of a step of the method of FIG. 2, in accordance with an embodiment of the invention; FIG. 9 is a schematic representation of a network depicting a performance of a step of the method of FIG. 2, in accordance with an embodiment of the invention; FIG. 10 is a schematic representation of a network in accordance with another embodiment of the invention; FIG. 11 is a schematic representation of a network in accordance with another embodiment of the invention; FIG. 12 is another schematic representation of the network of FIG. 11; FIG. 13 is a schematic representation of a network in accordance with another embodiment of the invention; FIG. 14 is a schematic representation of a network in accordance with another embodiment of the invention; FIG. 15 is another schematic representation of the network of FIG. 14; FIG. 16 is another schematic representation of the network of FIG. 14; FIG. 17 is a schematic representation of a network in accordance with another embodiment of the invention; FIG. 18 shows a flow-chart depicting a method of obtaining network knowledge in accordance with another embodiment of the invention; FIG. 19 is a schematic representation of a network in accordance with another embodiment of the invention; FIG. 20 shows a flow-chart depicting a method of exchanging information to establish a connection between nodes in accordance with another embodiment of the invention; FIG. 21 shows a flow-chart depicting an initialization process for a method of establishing a connection between nodes in accordance with another embodiment of the invention; FIG. 22 is a schematic representation of a network showing the additive property of cumulative link cost for a method of spreading node knowledge in accordance with another embodiment of the invention; FIG. 23 shows a flow-chart depicting the flow of node knowledge through a network for a method of spreading node knowledge in accordance with an embodiment of the invention; FIG. 24 shows a flow-chart depicting the flow of node knowledge through a network for a method of spreading node knowledge in accordance with an embodiment of the invention; FIG. 25 shows a flow-chart depicting the flow of node knowledge through a network for a method of spreading node knowledge in accordance with an embodiment of the invention; FIG. 26 shows a flow-chart depicting the flow of node knowledge through a network for a method of spreading node knowledge in accordance with an embodiment of the invention; FIG. 27 is a schematic representation of a network showing a method for detecting an isolated core in accordance with an embodiment of the invention; FIG. 28 shows a flow-chart depicting a method for routing through a network using TCP/IP as an example of a protocol that can be emulated, in accordance with an embodiment of the invention; FIG. 29 is a schematic representation of a network showing node A directly connected to nodes B and C; node C only connected to node A; and node B directly connected to four nodes; FIG. 30 shows a flow-chart depicting how service time on a queue can be calculated in accordance with an embodiment of the invention; FIG. 31 is a schematic representation of a network showing an arrangement of nodes and queues in accordance with an embodiment of the invention; FIG. 32 shows a number of flow-charts depicting a series of steps showing knowledge of a queue propagating a network in accordance with an embodiment of the invention; FIG. 33 is a schematic representation of a network showing every node in the network having just become aware of the EUS created queue, in accordance with an embodiment of the invention; FIG. 34 is a schematic representation of the network of FIG. 33 with one of the connections between the node with the EUS created queue removed; FIG. 35 is a schematic representation of the network of FIG. 33 with the directly connected node that lost its connection to the node with the EUS created queue set to a latency of infinity; FIG. 36 is a schematic representation of the network of FIG. 33 with all the node's ‘chosen destinations’ at infinity; FIG. 37 is a schematic representation of the network of FIG. 33 with all nodes that can be set to infinity being set to infinity; FIG. 38 is a schematic representation of the network of FIG. 33 with every node that has been set to infinity paused for a fixed amount of time, and then picking the lowest latency destination it sees that is not infinity; FIG. 39 is a schematic representation of the network of FIG. 33 showing that as soon as a node that was at infinity becomes non-infinity it tells the nodes directly connected to it immediately; FIG. 40 shows a flow-chart depicting the incoming latency update outlined in the schematic representations of FIGS. 33-39; FIG. 41 shows a flow-chart depicting latency at infinity; FIG. 42 is a schematic representation of a network showing the data stream on nodes between the ultimate sender and ultimate receiver; FIG. 43 is a schematic representation of a network showing an example of a potential loop to be avoided; FIG. 44 shows a chart comparing the median latency over a time period to the maximum latency over another time period; FIG. 45 is graph depicting bytes of data in queue over time, and showing minimum queue levels during time intervals; FIG. 46 is a schematic representation of a network showing that when a node at capacity sees a GUID it sent to a possible additional chosen destination it knows that choice would be a bad choice; FIG. 47 shows a flow-chart depicting a method of deciding when to add/remove a chosen destination while not ‘At Capacity’; FIG. 48 is a schematic representation of a network showing a loop that was accidentally created in nodes not in the data stream; FIG. 49 is a schematic representation of a network showing node A and node B negotiating so that node A can send to node B; FIG. 50 is a schematic representation of a network showing how node A indicates it wants to send more data; FIG. 51 is a schematic representation of a network showing how two nodes can negotiate transfers of messages when a quota is limited; FIG. 52 is a schematic representation of a network showing how two nodes can negotiate transfers of messages when a quota is limited; FIG. 53 is a schematic representation of a network showing how two nodes can negotiate transfers of messages when a quota is limited; and FIG. 54 is a schematic representation of a network showing each node's next best step to the core, and that same network rearranged to better illustrate the hierarchy this process creates. DETAILED DESCRIPTION OF THE INVENTION Referring now to FIG. 1 a network in accordance with an embodiment of the invention is indicated generally at 30. Network 30 comprises a plurality of nodes N1, N2 and N3. Collectively, nodes N1, N2 and N3 are referred to as nodes N, and generically they are referred to as node N. This nomenclature is used for other elements discussed herein. Node N1 is connected to node N2 via a first physical link L1. Node N2 is connected to node N3 via a second link L2. Node N1 is a neighbour to node N2 and likewise node N2 is a neighbour to node N1, since they are connected by link L1. By the same token, node N3 is a neighbour to node N2 and likewise node N2 is a neighbour to node N3, since they are connected by link L2. Thus, the term “neighbour” (and variants thereof, as the context requires) is used herein to refer to nodes N that are connected another node N by a single link L. Each node N is any type of computing device that is operable to communicate with another node N via a respective link L. Any type of computing device is contemplated, such a personal computer (“PC”), a laptop computer, a personal digital assistant (“PDA”), a voice over internet protocol (“VOIP”) landline telephone, a cellular telephone, a smart sensor, etc., or combinations thereof. Each node N can be different types of computing devices. Each link L is based on any type of communications link, or combinations or hybrids thereof, be they wired or wireless, including but not limited to OC3, T1, Code Division Multiple Access (“CDMA”), Orthogonal Frequency Multiple Access (“OFDM”), Global System for Mobile Communications (“GSM”), Global Packet Relay Service (“GPRS”), Ethernet, 802.11 and its variants, Bluetooth etc. It should now be understood that the types of computing devices used to implement a particular node N, and the types of links L therebetween are not particularly limited, and that in general terms, each node N is operable to connect and communicate with any neighbouring nodes N via the respective link L therebetween. Each node N maintains a network information database D that is configured to maintain knowledge about at least some of the other nodes N within network 30. Each database D is maintained in volatile storage (e.g. random access memory (“RAM”)) and/or non-volatile storage (e.g. hard disc drive) or combinations of volatile or non-volatile storage, in a computing environment associated with its respective node N. Database D is used by each node N to locate other nodes N in network 30, so that the particular node N can send traffic to that other node N and/or to share knowledge about those other nodes N. Each database D is shown on FIG. 1 as an oval indicated with the reference D and located within its respective node N, to represent that node N maintaining its own respective database D. More particularly, database D1 is shown within node N1, database D2 is shown within node N2, and database D3 is shown within node N3. The size, complexity and other overhead metrics that define the structure of each database D are chosen so that a particular database D only occupies a portion of the overall computing resources that are available in its respective node N. The structure of database D is thus typically, though not necessarily, chosen to leave a significant portion of the computing resources of node N free to perform the regular computing tasks of that node N. Further details about such overhead metrics will be discussed in greater detail below. However, for the exemplary network 30 in FIG. 1, it will be assumed that all nodes N have substantially equal computing resources and that all links L have substantially the same service characteristics. (As used herein, the term “service characteristics” as applied to links L includes any known quality of service (“QOS”) metrics including bandwidth, latency, bit error rate, etc that can be used to assess the quality of a link L. Service characteristics can also include pricing, in that the financial cost incurred to carry traffic over one link may be different than the financial cost to carry traffic over another link). It will thus be assumed that each database D has substantially the same structure—an example of such a structure being shown in Table I. TABLE I Exemplary Structure of each Database D Row Number Column 1 Column 2 Column 3 Heading Rank Node name Best Neighbour In general terms, each database D provides a list of at least some of the nodes N in network 30, other than the node N that is maintaining the particular database D (“other nodes N”). Each database D also ranks those other nodes N according to their importance within network 30. Metrics that reflect importance include, but are not limited to, the proximity of such other nodes N, and/or which of the other nodes N carries a proportionately greater share of traffic in network 30, and/or the proximity of a node N to a data flow going to another node N. Other metrics will now occur to those of skill in the art, some of which will be discussed in greater detail below. Each database D also identifies those other nodes N, and the neighbouring node N that represents the next best step to reach a respective other node N. Explaining Table I in greater detail, in Column 1 of Table I, “Rank”, indicates a number, increasing in value for each row in database D based on the number of other nodes N that are maintained in the particular database D. In Column 2 of Table I, “Node name” identifies the specific other node N. Such a node name can be based on any known or future network addressing scheme. Examples of known node addressing schemes include telephone numbers, or Medium Access Control (“MAC”) addresses, or Internet Protocol (“IP”) addresses. Such an addressing scheme can be chosen according to other factors affecting the design of network 30 and/or the nodes N therein. Of note, however, in the addressing scheme the name of each node N need not reflect the location of that node N in the network, as is found in other addressing schemes—e.g. telephone numbers that have area codes corresponding to a geographic location. In order to simplify explanation of the embodiments herein, the node name is identified according to the reference character in the Figures. For example, where a Node Name entry under Column 2 indicates “N1”, then node N1 is being identified. In Column 3 of Table I, “Best Neighbour” indicates which of the neighbour nodes N provides the next best step in an overall route to reach the other node N named in Column 2. [In the present embodiment, the term “Best Neighbour” is used, but this should not be construed in a limiting sense for all embodiments of the invention, in that any desired criteria to determine a “Best Neighbour” or otherwise desired neighbour can be chosen.] Thus, Column 3 will always identify a neighbour node N, while Column 2 need not indicate a neighbour node N. It should be understood that entries in Column 3 need not actually be the name of the neighbour node N, according to the same addressing scheme used for Column 2, but can be any indicator of that particular neighbour node N. However, to simplify explanation of the embodiments herein, entries in Column 3 will actually reflect the name of the neighbour node N. When network 30 is initialized (e.g. when all of the nodes N each connect to each other according to the topology shown in FIG. 1), the contents of each database D will be empty, except that each database D will contain a “null” entry identifying the particular node N that owns the particular database D. Table II thus shows how database D1 is initially populated with a “null” entry, identifying node N1. TABLE II Initial contents of Database D1 Row Number Column 1 Column 2 Column 3 Heading Rank Node name Best Neighbour Row 0 Ø N1 N/A Explaining Table II in greater detail, in Row 0 of Column 1 of Table II, the entry is given a null entry of “0”, to indicate that this particular information in database D1 is about the actual node N1 that owns that database D1. In Row 0 of Column 2 of Table II, the entry is “N1”, to identify node N1 by name. In Row 0 of Column 3 of Table II, the entry is “N/A”, to indicate that the best neighbour is inapplicable, since this entry of Table II refers to the owner of database D1. Likewise, Table III thus shows how database D2 is initially populated with a “null” entry, identifying node N2. TABLE III Initial contents of Database D2 Row Number Column 1 Column 2 Column 3 Heading Rank Node name Best Neighbour Row 0 Ø N2 N/A Likewise, Table IV thus shows how database D3 is initially populated with a “null” entry, identifying node N3. TABLE IV Initial contents of Database D2 Row Number Column 1 Column 2 Column 3 Heading Rank Node name Best Neighbour Row 0 Ø N3 N/A In order to populate a remainder of each database D, and maintain their contents, a microprocessor on each node N will perform a set of programming instructions. Those instructions can be substantially the same for each node N. Referring now to FIG. 2, a flowchart representing a method for maintaining network knowledge in accordance with an embodiment of the invention is indicated generally at 200. Method 200 can be implemented into a set of programming instructions for execution on a microprocessor on each node N to populate and maintain the contents of each database D. In order to assist in the explanation of the method, it will thus be assumed that method 200 is operated on each node N in system 30 in order to maintain the database D respective to that node N. The following discussion of method 200 will thus lead to further understanding of system 30 and its various components. (However, it is to be understood that system 30 and/or method 200 can be varied, and need not be performed in the exact sequence shown in FIG. 2, and that system 30 and/method 200 need not work exactly as discussed herein, and that such variations are within the scope of the present invention.) Thus, before beginning explanation of method 200, it will be assumed that database D for each node N has been populated only according to Tables II, III and IV, and that each node N has been activated and is physically connected to each other according to the structure of links L shown in FIG. 1. Beginning first at step 210, the presence of neighbours is determined. In general terms, at step 210 each node N determines whether it has any new neighbouring nodes N, or whether any existing neighbouring nodes N have ceased connecting that that node N. When step 210 is first performed by node N1, node N1 will thus send out an initialization message over link L1 to node N2 in order to query the existence of node N2 and the end of link L1. Such an initialization message can be performed according to any known means corresponding to the type of protocol used to implement link L1. Likewise, step 210 will also be performed by node N2, and node N2 will thus send out a network initialization signal over link L1 to node N1 in order to query the existence of node N1. By the same token, node N2 will thus send out a network initialization signal over link L2 to node N3 in order to query the existence of node N3. Finally, step 210 will also be performed by node N3, and node N3 will thus send out a network initialization signal over link L2 to node N2 in order to query the existence of node N2. Referring now to FIG. 3, this initial performance of step 210 by each node N is represented by showing a plurality of initialization messages IM being sent according to the above. Specifically, initialization message IM1-2 is being sent from node N1 to node N2; initialization message IM3-2 is being sent from node N3 to node N2; initialization message IM2-3 is being sent from node N2 to node N3; initialization message IM2-1 is being sent from node N2 to node N1. In a present embodiment, initialization messages IM do not exchange node knowledge, in order to simplify initialization messages IM, and allow node knowledge of a node N to spread in substantially the same manner for all nodes N. This initialization message IM can contain processing and memory characteristics of node N as it relates to the node's ability to maintain network knowledge. Such processing and memory characteristics can include, the memory of the node N that is dedicated to maintaining network knowledge, and the like. In the present embodiment, however, node names N themselves are not exchanged as part of the initialization messages IM. As a result of locating neighbours using initialization messages IM, each node N will now be aware of its neighbouring nodes N, and thus be in a position to begin populating and maintaining its respective database D by making use of neighbouring databases D. Thusly, referring again to FIG. 2, method 200 will advance from step 210 to step 220 at which point network knowledge will be exchanged between neighbour nodes N, such neighbours having been identified at step 210. Each node N can now make use of a neighbouring database D to gain more knowledge about network N. Referring now to FIG. 4, the initial performance of step 220 by each node N is represented by showing a set of bi-directional knowledge exchange messages KEM. The knowledge exchange between node N1 and node N2 is indicated as knowledge exchange message KEM1-2, while the knowledge exchange between node N2 and node N3 is indicated as knowledge exchange message KEM2-3. Referring again to FIG. 2, method 200 then advances from step 220 to step 230, at which point local knowledge is updated as a result of the information exchange from step 220. As a result of exchanging messages KEM, databases D1, D2 and D3 can be updated to reflect information about neighbouring nodes N, as shown in Tables V, VI, VII respectively. Table V thus shows how database D1 is now populated after the initial performance of step 230 by node N1. TABLE V (Updated from Table III) Database D1 Row Number Column 1 Column 2 Column 3 Heading Rank Node name Best Neighbour Row 0 Ø N1 N/A Row 1 1 N2 N2 Explaining Table V in greater detail, in Row 0 remains the same as from Table III. However, Row 1 is now populated, showing that node N1 now has knowledge of a node named node N2, and that node N2 is the best neighbour through which node N2 can be reached. Likewise, Table VI thus shows how database D2 is now populated after the initial performance of step 230 by node N2. TABLE VI (Updated from Table IV) Database D2 Row Number Column 1 Column 2 Column 3 Heading Rank Node name Best Neighbour Row 0 Ø N2 N/A Row 1 1 N1 N1 Row 2 2 N3 N3 Explaining Table VI in greater detail, in Row 0 remains the same as from Table IV. However, Row 1 is now populated, showing that node N2 now has knowledge of a node named node N1, and that node N1 is the best neighbour through which node N1 can be reached. By the same token, Row 2 is now populated, showing that node N2 now has knowledge of a node named node N3, and that node N3 is the best neighbour through which node N3 can be reached. Note that node N1 has been given a rank of “1”, while node N3 has been given a rank of “3”. In the present example, such rankings were made purely as matter of convenience given that no metrics exist in which to actually choose which to rank higher. However, rankings made on more complex bases will be discussed in greater detail below. Likewise, Table VII thus shows how database D3 is populated after the initial performance of step 230 by node N3. TABLE VII (Updated from Table V) Database D3 Row Number Column 1 Column 2 Column 3 Heading Rank Node name Best Neighbour Row 0 Ø N3 N/A Row 1 1 N2 N2 Explaining Table VII in greater detail, in Row 0 remains the same as from Table V. However, Row 1 is now populated, showing that node N3 now has knowledge of a node named node N2, and that node N2 is the best neighbour through which node N2 can be reached. The contents of Tables V, VI and VII are shown as knowledge paths K, represented by dotted lines in FIG. 5. Knowledge path K1-2 corresponds with Row 1 of Table V, indicating that node N1 has knowledge of N2; knowledge path K2-1 corresponds with Row 1 of Table VI, indicating that node N2 has knowledge of N1; likewise knowledge path K2-3 corresponds with Row 2 of Table VI, indicating that node N2 has knowledge of node N3; and knowledge path K3-2 corresponds with Row 1 of Table VII, indicating node N3 has knowledge of node N2. Payload traffic generated at an origin node N that is intended for a destination node N can now actually be delivered to nodes N in accordance with knowledge paths K. Where a knowledge path exists between an origin node N and a destination node N. Such delivery of payload traffic can be effected via the best neighbour routings shown in Column 3, to the extent that Column 2 is populated in the database D of the origin node N with network knowledge about the destination node N. (As used herein, “payload traffic” or “payload” refers to any data generated by an application executing on the origin node N that is intended for a destination node N. For example, where nodes N are computers, then payload traffic can include emails, web pages, application files, printer files, audio files, video files or the like. Where nodes N are telephones, then payload traffic can include voice transmissions. Other types of payload data will now occur to those of skill in the art.) More specifically, nodes N1 and nodes N2 can now exchange payload traffic, since they have knowledge of each other. Nodes N2 and N3 can also exchange payload traffic, since they have knowledge of each other. However, at this point, nodes N1 and N3 cannot exchange traffic since they do not have knowledge of each other. Having now completely performed method 200 once, method 200 then cycles back from step 230 to step 200 where method 200 begins anew for the second time. Returning again to step 210, the presence of neighbours are determined. During this second exemplary cycle through method 200, it will be assumed that no new nodes N are added to network 30, and no existing nodes N are removed. Accordingly, nothing occurs at step 210 since no changes have occurred and method 200 advances from step 210 to step 220. Continuing with the present example, referring again to FIG. 2, method 200 will advance again from step 210 to step 220 at which point additional network knowledge will be exchanged between neighbour nodes N. Once again, each node N can now make use of a neighbouring database D to gain more knowledge about network N. Referring now to FIG. 6, the second performance of step 220 by each node N is once again represented by bi-directional knowledge exchange messages KEM. The knowledge exchange between node N1 and node N2 is indicated as knowledge exchange message KEM1-2, while the knowledge exchange between node N2 and node N3 is indicated as knowledge exchange message KEM2-3. Referring again to FIG. 2, method 200 then advances, for the second time, from step 220 to step 230, at which point local knowledge is updated as a result of the information exchange from step 220. As a result of exchanging messages KEM, databases D1, D2 and D3 can be updated to reflect information about neighbouring nodes N, as shown in Tables VIII, IX, X respectively. Table VIII thus shows how database D1 is now populated after the second performance of step 230 by node N1. TABLE VIII (Updated from Table V) Database D1 Row Number Column 1 Column 2 Column 3 Heading Rank Node name Best Neighbour Row 0 Ø N1 N/A Row 1 1 N2 N2 Row 2 2 N3 N2 Explaining Table V in greater detail, in Rows 0 and 1 remain the same as from Table V. However, Row 2 is now populated, showing that node N1 now has knowledge of a node named node N3, and that node N2 is the best neighbour through which node N3 can be reached. Likewise, Table IX thus shows how database D2 is now populated after the initial performance of step 230 by node N2. TABLE IX (Updated from Table VI) Database D2 Row Number Column 1 Column 2 Column 3 Heading Rank Node name Best Neighbour Row 0 Ø N2 N/A Row 1 1 N1 N1 Row 2 2 N3 N3 Explaining Table IX in greater detail, in Rows 0, 1 and 2 remain the same as from Table VI, since there are no new nodes N in network 30 for node N2 to become aware of through exchanging messages with its neighbouring nodes N. Likewise, Table X thus shows how database D3 is populated after the initial performance of step 230 by node N3. TABLE X (Updated from Table VII) Database D3 Row Number Column 1 Column 2 Column 3 Heading Rank Node name Best Neighbour Row 0 Ø N3 N/A Row 1 1 N2 N2 Row 2 2 N1 N2 Explaining Table VII in greater detail, in Rows 0 and 1 remain the same as from Table V. However, Row 2 is now populated, showing that node N3 now has knowledge of a node named node N1, and that node N2 is the best neighbour through which node N1 can be reached. The contents of Tables X, IX and X are shown as knowledge paths K, represented by dotted lines in FIG. 7. In FIG. 7, (and as previously shown in FIG. 5), knowledge path K1-2 indicates that node N1 has knowledge of N2; knowledge path K2-1 indicates node N2 has knowledge of N1; likewise knowledge path K2-3 indicates that node N2 has knowledge of node N3; and knowledge path K3-2 indicates node N3 has knowledge of node N2. However, FIG. 7 also now includes two additional knowledge paths: knowledge path K1-3 indicates that nodes N1 now has knowledge of node N3, and likewise knowledge path K3-1 indicates that node N3 now has knowledge of node N1. Payload traffic generated at an origin node N that is intended for a destination node N can now actually be delivered to nodes N in accordance with knowledge paths K. Where a knowledge path exists between an origin node N and a destination node N. Such delivery of payload traffic can be effected via the best neighbour routings shown in Column 3, to the extent that Colun=2 is populated in the database D of the origin node N with network knowledge about the destination node N. Thus, more specifically, all nodes N can all now exchange payload traffic, since they have knowledge of each other. Of particular note, after this pass through method 200, node N1 and node N3 can send payload traffic to each other, via node N2 as the step between them. Having now completely performed method 200 twice, method 200 then cycles back from step 230 to step 200 where method 200 begins anew. Prior to the performance of the third exemplary cycles through method 200, it will be assumed that node N3 is removed from network 30 due to a failure of link L2, as represented in FIG. 8. Returning again to step 210, the presence of neighbours are determined. This third time, during the exchange of initialization messages IM, nodes N2 and N3 will determine that each other is no longer a neighbour. At step 220 knowledge is exchanged with neighbours according to the neighbours found present at step 210. Finally, at step 230, local knowledge is updated based on the exchange. After step 230, and as shown in FIG. 8, the result is that database D1 remains the same, maintaining the contents as shown in Table VIII, because insufficient cycles of method 200 have occurred for the loss of node N3 to propagate to database D1. However, database D2 is now updated in accordance with Table XI. TABLE XI (Updated from Table IX) Database D2 Row Number Column 1 Column 2 Column 3 Heading Rank Node name Best Neighbour Row 0 Ø N2 N/A Row 1 1 N1 N1 Database D3 is also updated to reflect the initial data found in Table IV. This is represented in FIG. 8, and no existing nodes N are removed. Accordingly, nothing occurs at step 210 since no changes have occurred and method 200 advances from step 210 to step 220. The contents of the databases D after this third pass of method 200 are reflected by the knowledge paths K shown in FIG. 8. During a fourth pass of method 200, the loss of node N3 will finally propagate to node N1, resulting in the knowledge paths K shown in FIG. 9. (Those of skill in the art will recognize that the foregoing is simplified explanation for purposes of explanation, which when implemented can cause the introduction of a trivial loop. To address this, a ‘poison reverse’ can be introduced to get rid of the trivial loop that gets introduced in any network when a node is removed. A poison reverse is discussed in greater detail below. to further reduce introductions of loops, a delay can be introduced during the spread of node knowledge, while implementing a ‘zero’ delay (e.g. substantially instantaneous) removal of node knowledge. Finally when the distance from data flow (discussed in greater detail below) reaches a certain limit a node informs its neighbouring nodes to remove knowledge of that particular node even if it still has valid knowledge of that node. A more detailed discussion of node removal is provided further below.) It should now be understood that the teachings herein are applicable to networks of greater complexity than network 30. For example, referring now to FIG. 10, a slightly more complex network in accordance with another embodiment of the invention is indicated generally at 30a. Network 30a includes substantially the same elements as network 30, and like elements include like references but followed by the suffix “a”. More specifically, network 30a includes more nodes Na and links La, but the basic structure of those nodes Na and links La are substantially the same as their counterparts in system 30. To simplify explanation, however, network 30a is shown without specific tables showing the contents of databases Da. Network 30a includes nodes Na1, Na2 and Na3 that are connected via links La1 and La2 like their respective counterparts nodes N1, N2 and N3 in network 30. In this example, it is initially assumed that network 30a has undergone two complete passes through method 200 and thus databases D are in the same state as shown for network 30 in FIG. 7. In contrast to network 20, however, it is also assumed that network 30a includes a fourth node Na4, that is initially, not connected to any other node Na. Referring now to FIG. 11, assume that node N4a joins the rest of network 30a by the formation of link L3a spanning node N4a and node N2a; and by the formation of link L4a spanning node N4a and node N3a. After a sufficient number of cycles of method 200 are performed by each node N, additional knowledge paths K (as shown in FIG. 11) will form according to the updated contents of databases D, as aggregated in Table XII. TABLE XII Databases Da Database D1a Database D2a Database D3a Database D4a 2 3 5 6 8 9 11 12 1 Node Best 4 Node Best 7 Node Best 10 Node Best Row Rank Name Neighbour Rank Name Neighbour Rank Name Neighbour Rank Name Neighbour 1 Ø N1a N/A Ø N2a N/A Ø N3a N/A Ø D4a N/A 2 1 N2a N2a 1 N3a N3a 1 N2a N2a 1 N2a N2a 3 2 N3a N2a 2 N4a N4a 2 N4a N4a 2 N3a N3a 4 3 N4a N2a 3 N1a N1a 3 N1a N2a 3 N1a N2a Payload traffic generated at an origin node Na that is intended for a destination node Na can now actually be delivered in accordance with knowledge paths Ka. For example, assume that node N4a wishes to send payload traffic to node N1a. Using the information in Table XII, it can be seen that traffic will be routed to node N1a from node N4a via node N2a. This traffic path P is shown in FIG. 12, which shows network 30a in the same state as FIG. 11, but with knowledge paths Ka removed so that traffic path P can be seen more clearly. At this point it can be noted that various nodes can reach other nodes through different paths, even though certain preferred paths have been identified. Such preferred paths have been chosen since the embodiments thus far have assumed that all links L and La have substantially the same service characteristics. For example, in FIGS. 11 and 12, corresponding to Table XII, node N4a reaches node N1a via node N1a. This is reflected in Table XII at Row 4, Column 12, wherein node N2a is reflected as the next best neighbour to reach node N1a from node N4a. However, while less preferred in the example shown in Table XII, it is physically possible for payload traffic to be delivered along the path from node N4a, via node N3a and node 2a before final delivery to node N1a, which is the path that would be used if link L3a did not exist. However, in another embodiment, service characteristics for each link can vary, and databases for each node incorporate knowledge of such service characteristics when selecting a best neighbour as a next best step through which to route payload traffic. For example, referring now to FIG. 13, another network in accordance with another embodiment of the invention is indicated generally at 30b. Network 30b is substantially the same as network 30a, and like elements include like references but followed by the suffix “b”. More specifically, network 30b includes links Lb, which follow the same paths as links La in network 30a. Also, network 30b includes four nodes Nb, which are substantially the same as nodes Na in network 30a. However in network 30b each link Lb has different service characteristics, whereas in network 30a each link La has the same service characteristics. Table XIII shows an exemplary set of service characteristics for each link Lb. TABLE XIII Service Characteristics for Links Lb Column 1 Column 2 Column 3 Row Link Bandwidth Cost 1 L1b 1 Megabit/second $0.10 per kilobyte 2 L2b 10 Megabit/second $0.05 per kilobyte 3 L3b 0.5 Megabit/second $0.10 per kilobyte 4 L4b 10 Megabit/second $0.20 per kilobyte Explaining Table XIII in greater detail, column 1 identifies the particular link Lb in question. Column 2 identifies the bandwidth of the link Lb identified in the same row. Column 3 indicates the financial cost for carrying traffic over a particular link Lb in terms of cents per kilobyte. (It should now be understood that Table XIII can include any other service characteristics that are desired, such as bit error rate, latency etc.) The information for each link Lb can thus be made part of each database Db, and propagated through network 30b using method 200 or a suitable variant thereof, in much the same manner as node knowledge can be propagated throughout network 30b. Databases Db respective to each node Nb know the details of each link Lb to which they are directly connected. For example, Node N4b will know the details of links L3b and L4b as shown in Table XIII. By the same token, node N3b will know the details of links L4b and L2b. In a present embodiment, each node Nb only knows about itself and the links Lb that it has to directly connected nodes Nb. But each node Nb need no knows anything about the overall network topology. However, each node Nb Databases Db respective to each node Nb on either end of a particular pathway will know the cumulative service characteristics associated with the links Lb that define that pathway, once that database Db has knowledge of that node. Thus, once node N4b knows about node N1b, node N4b will also know the cumulative service characteristics, (and therefore the cumulative ‘cost’) of all links Lb between node N4b and node N1b. Thus, once a particular node Nb has information about the characteristics of a particular link, then that node Nb can use such information in order to determine the “Best Neighbour” as the next best step through which to route traffic. For example, in Table XIII it can be seen that the bandwidth of link L3b is only 0.5 Megabits/second—whereas the bandwidth of link L4b and link L2b are both ten Megabits/second. Thus, payload traffic sent from node N4b to node N2b will be delivered to node N2b much faster if it is sent via node N3b, rather than if it is sent directly over link L3b. Thus, using Table XIII node N4b can determine that node N3b is the next best step to reach both nodes N2b and nodes N1b, if speed of delivery of payload traffic is a priority. Table XIV thus shows how a portion of databases Db would appear if node N4b made such a determination (assuming that the information in Table XIII is not shown in Table XIV). TABLE XIV Databases Db Database D1b Database D2b Database D3b Database D4b 2 3 5 6 8 9 11 12 1 Node Best 4 Node Best 7 Node Best 10 Node Best Row Rank Name Neighbour Rank Name Neighbour Rank Name Neighbour Rank Name Neighbour 1 Ø N1b N/A Ø N2b N/A Ø N3b N/A Ø D4b N/A 2 1 N2b N2b 1 N3b N3b 1 N2b N2b 1 N2b N3b 3 2 N3b N2b 2 N4b N4b 2 N4b N4b 2 N3b N3b 4 3 N4b N2b 3 N1b N1b 3 N1b N2b 3 N1b N3b By the same token, FIG. 12 shows the path Pb of payload traffic for traffic originating from node N4b destined for node Nb based on the contents of database D4b as shown in Table XIV. In FIG. 12, path Pb does not travel via link L3b, but instead travels via links L4b and L2b. It should now be understood that complex, and multiple criteria can be employed when determining the best neighbour through which to route traffic. Table XIV can thus be populated optimizing service characteristics of link Lb, optimizing for bandwidth, cost, bit error rate, etc. Of course, Table XIV would change if the best neighbour was chosen based on the next best step having the least financial cost, and ignoring bandwidth altogether. Referring again to Table XIII, in this case, since link L3b is financially less expensive than link L4b, then node N4b would choose node N2b as its next best step to reach node N2b and node N1b, and thus database D1b would appear the same as database D1a in Table XII. It should now be apparent that the next best step can be based on a set of complex criteria for evaluating each link—for example, some overall rating of a link Lb can be determined by combining columns 2 and columns 3 of Table XIII, to provide a service characteristic rating that is a combination of both bandwidth and financial cost for a particular link. It is again to be emphasized that the teachings herein are applicable to networks of greater complexity than networks 30, 30a and 30b. For example, referring now to FIG. 14, a more complex network in accordance with another embodiment of the invention is indicated generally at 30c. Network 30c includes the same types of elements as networks 30, 30a and 30b and like elements include like references but followed by the suffix “c”. Of note, in this embodiment it is assumed that all links Lc have substantially the same length and substantially the same service characteristics, though in other embodiments links Lc can have varying lengths and service characteristics, similar to links Lb. Network 30c includes more nodes Na and links La, and to simplify explanation, however, network 30c is shown without specific tables showing the contents of databases Dc. In contrast to networks 30, 30a and 30b, however, in network 30c it is assumed that databases Dc have only a limited number of rows in order to set an upper limit on the memory resources of each node Nc that will be consumed by its respective database Dc. Thus, in this network 30c, each node is does not maintain knowledge about the entire network 30c, but only a portion of the network 30c. (Such a configuration is in fact presently preferred when the teachings herein are applied to networks of a size where knowledge of the entire network results in an impractically large consumption of the overall computing resources of a given node.) For purposes of assisting in explanation, it will be assumed that each database Dc can store eleven rows of information. The first row is the null row as previously described in relation to Table II, which identifies the node Nc to which a particular database Dc belongs. The remaining nine rows allow the database Dc to maintain knowledge of nine other nodes Nc within network 30c. Note that it is not necessary for each node Nc to have the same capacity for storage, and such capacity need not be fixed but can be dynamically allocated, either automatically or manually, as the needs of a particular node Nc change, but nodes Nc in network 30c are constructed to a limit of nine other nodes for explanation purposes. Databases Dc for each node Nc maintain a concept of a “core”. Where a specific node Nc is not included in a particular database Dc, then the core represents a default path for which that given node Nc may be located. As shown in FIG. 14, network 30c includes a core Cc which lies along link L6c, the details of which will be discussed in greater detail below. In general, it is presently preferred to ensure that the aggregate storage capacity of at least the databases Dc that comprise the core Cc is sufficient to ensure that the databases Dc that define the core Cc have knowledge of every node Nc within the network 30c. Accordingly, the size of the network according to the architecture of network 30c will thus complement the collective storage capacity of the two nodes Nc that define the core Cc. Thus, in the present example, collectively, node N6c and node N9c have sufficient capacity such that the nine rows in each of databases D6c and D9c are sufficient to maintain knowledge of every node within network 30c. Thus, while each node Nc performs method 200, it will “hear” of more other nodes Nc than that node Nc will store. Accordingly, each node Nc is also operable to perform a prioritization operation to choose which nine other nodes Nc within network 30c to maintain knowledge of within its database Dc. Such a prioritization operation can be based on any prioritization criterion or criteria, or combinations thereof, such as which other nodes Nc are closest, which other nodes Nc carry the most traffic, which other nodes Nc does that particular node typically send payload traffic, etc, and such other criteria as will now occur to those of skill in the art. Such prioritization criteria thus also provides the “rank” of each node Nc in order of importance, thereby defining the order in which the database Dc is populated, and the order for which node knowledge should be sent to other nodes Nc in the network. In the present example, it will be assumed that the prioritization criteria for each node Nc is to populate its database Dc in order maintain knowledge of: (a) the other nodes Nc that are closest that that node Nc (“proximal nodes Nc”). Proximal nodes Nc are ranked in order of proximity; (b) originating or destination nodes Nc with which the node Nc must have knowledge of in order to pass payload traffic on behalf of that originating or destination node Nc; (“originating or destination nodes Nc”). Originating and destination nodes are ranked according to the amount of payload traffic being carried on their behalf, and supersede proximal nodes. (c) the other nodes Nc with which that node Nc sends or receives payload traffic; (“payload traffic nodes Nc”). Payload traffic nodes Nc are ranked according to the importance of a particular payload traffic in relation to another, and supersede all proximal nodes and supersede up to half of the originating or destination nodes Nc. Importance of payload traffic can be based on volume of traffic, or speed of traffic, or the like; (d) up to a maximum of nine other nodes Nc during any particular cycle of method 200. It is to be reiterated that the foregoing prioritization criteria is simplified for purposes of explanation of the present embodiment. In another, more presently preferred embodiment, nodes are ordered by their distance from a marked data stream value, except in such cases where: 1. This node is in the path of a High Speed Propagation Path (“IISPP”, which is discussed in greater detail below) for this destination node, and this directly connected node is: In the path to the core and the HSPP is a notify HSPP. One of the nodes that told us of this HSPP and the HSPP is a request HSPP. 2. This node is marked in the data stream for this destination node. If a node is marked in the data stream it will tell its directly connected nodes that have not marked it in the data stream a Distance from Data Stream (also referred herein as a Distance From Stream or “DFS”) of 0. those that have marked it in the data stream it will tell a DFS equal to the link Cost (“LC”) associated with the Service Characteristics of the links to the destination node. This will be explained in greater detail below.] The formation of core Cc in network 30c will now be explained. In network 30c, it is initially assumed that nodes N2c through N13c are connected by links L1c through L11c, as shown in FIG. 14. It is also assumed that nodes N1c and nodes N14c are initially not connected to the remainder of network 30c. It is also assumed that, initially, no node Nc is attempting to send payload traffic to another node Nc, and that method 200 has been performed by each of nodes N2c and N13c to populate their respective databases Dc, subject to the prioritization criteria described above. FIG. 15 shows the other nodes Nc with which database D2c will be populated, represented as a closed dashed Figure and referred to herein as knowledge path block K2c-xc. Knowledge paths block Kc-xc surrounds all of the other nodes Nc of which node N2c is aware, i.e. nodes N3c-N10c, an node N12c. FIG. 16 shows the other nodes Nc with which database D6c will be populated, represented as a closed dashed Figure and referred to herein as knowledge path block K6c-xc. Knowledge path block K6c-xc surrounds all of the other nodes Nc of which node N6c is aware, i.e. nodes N2c-N5c, and nodes N7c-N11c, and node N12c. While not shown in the Figures, those of skill in the art will now appreciate the contents of the other databases Dc at this point in the present example. At this point, it is also useful to note that payload traffic between any of nodes N2c-N6c and any of nodes N8c-N13c will all need to pass through link L6c. Thus, for this particular network, link L6c represents the “core” of network 30c at this point in the example. The core is shown in FIG. 14 as an ellipse encircling link L6c and indicated at Cc. The fact that link L6c is specifically the core Cc of network 30c need not be expressly maintained in each database Dc. Rather, each database Dc will determine a “Best Neighbour” indicating a neighbour that is the next best step in order to reach core Cc. The “Best Neighbour” to reach core Cc can be determined by examining database Dc to find which neighbouring node Nc is most frequently referred to as the “Best Neighbour” to reach the other nodes that are expressly maintained in database Dc. In the event that no neighbouring node Nc appears more frequently as a Best Neighbour, then the Best Neighbour appearing in Row 1, associated with the top-most ranked other node, can be selected as the Best Neighbour to reach the network 30c. A core is formed any time that two neighbouring nodes Nc point to each other as being the Best Neighbour to reach the core. (Applying this core determination method to an earlier example, in Table XII and FIG. 11 recall that the Best Neighbour to the core of network 30a for node N1a would be node N2a; the Best Neighbour to the core of network 30a for node N2a would be node N3a; the Best Neighbour to the core of the network 30a for node N3a would be Node N2a; and the Best Neighbour to the core of network 30a for node N4a would be node N2a. Since node N2a points to node N3a, and node N3a points to node N2a, then link L2a would be the “core” of network 30a.) It should now be apparent that when a network, such as network 30c, is first initialized a plurality of cores will form until method 200 is performed a sufficient number of times such that databases Dc are populated and maintain a substantially steady state. Also, as nodes Nc are added or removed, or links Lc are added or removed, (and/or other factors affecting the overall state of the network change), then the location of core Cc can change, and/or multiple cores can form. Building on the example shown in FIGS. 14-16, and referring now to FIG. 17, it will be assumed that two new links are added to network 30c. Specifically, link 12c now joins nodes N1c and N2c, while link 13c now joins nodes N13c and N14c. As method 200 is performed by nodes N1c and N14c, and re-performed by the remaining nodes Nc, the location of core Cc at link L6c will ultimately not change in this particular configuration of network 30c. However, the contents of each database Dc may change according to the above-mentioned prioritization criteria. For example, node N2c will add node N1c to its database D2c, and drop node 12c from database D2c. Also of note, node N1c will populate database D1c with knowledge about nodes N2c-N10c, while node N14c will populate database D14c with knowledge about nodes N5c-N13c. Thus, nodes N1c and N14c will not have knowledge of each other. Now assume that node N1c wishes to send payload traffic to node N14c. Since node N1c has no knowledge of node N14c, at this point node N1c can perform method 800 shown in FIG. 18 in order to gain such knowledge. Beginning at step 810, originating node N1c will receive a request to send payload traffic to destination node N14c. Such a request can come from another application executing on a computing environment associated with originating node N1c. (As an aside, and as will become more apparent from further teachings herein, to put this entire method in more colloquial terms, a request sent to a neighbor node can be in the form of: ‘if you see route information for my destination node, can you make sure to tell me about it so I can make a good choice on where to send my payload data’. If anode has some payload to send, but no place to send it, it will hang onto that payload until a timeout on the payload expires (if there is one), or it needs that room for other packets, or it gets told a route update that will allow it to route to a directly connected node.) Next, at step 820, a determination is made as to whether the destination node to which the payload traffic is destined is located in the local database Dc. In this example, recall that database D1c does not include information about destination node N14c, and so the result of this determination would be “no”, and method 800 would advance from step 820 to 830. (If, however, the destination node was in the database D1c, then at step 840, payload traffic could be sent via the Best Neighbour identified in the database, in much the same manner as was described in relation to network 30a in FIG. 12, or network 30b in FIG. 13.) Next, at step 830 a query will be sent towards the core asking for knowledge of destination node N14c. Such a query will be passed towards the core Cc, by each neighbouring node Nc, along the path of “Best Neighbours” that lead to core Cc, until the query reaches a node Nc that has knowledge of node N14c. Thus, each node Nc will receive the query, examine its own database Dc, and, if it has knowledge of destination node N14c, it will send such knowledge back through the path to originating node N1c. If the node Nc receiving the query does not have knowledge of destination node N14c, then it will pass the query on to the neighbouring node Nc that is its Best Neighbour leading to core Cc, until the query reaches a node Nc that has knowledge of node N14c. In the present example, the query from node N1c will follow the path from node N2c; to node N3c; to node N6c; and finally to node N9c, since node N9c will have knowledge of node N14c due the prioritization criteria defined above. Thus, the knowledge of node N14c will be passed back through node N6c; to node N3c; to node N2c and finally to node N1c, with nodes N6c, N3c, N2c each keeping a record of the knowledge of node N14c in their respective databases Dc so that they can pass payload traffic on behalf of network N1c. Next, at step 840 a response will eventually be received by the originating node Nc to the query generated at step 830. In the present example, node N1c will thus receive knowledge back from node N9c about node N14c, and, at step 850, node N1c will update its database D1c with knowledge of node N14c. Method 800 can then advance from step 850 to step 830 and payload traffic can be sent to node N14c from node N1c, in much the same manner as was described in relation to network 30a in FIG. 12, or network 30b in FIG. 13. Building on the example shown in FIG. 17, and referring now to FIG. 19, it will be assumed that three new links are added to network 30c. Specifically, link L14c is added to join node N12c and node N8c; link L15c is added between node N8c and node N5c; and link L16c is added between node N5c and node N2c. ach node Nc performs method 200 a number of times to absorb the knowledge of these new links Lc. As such knowledge propagates throughout network 30c, eventually, the path of payload traffic from node N1c to node N14c will travel via nodes N2c; N5c; N8c; N12c and N13c. It should now be understood that where links L14c, L15c and L16c existed prior to nodes N1c and N14c gaining knowledge of each other, then nodes N1c will initially gain knowledge of node N14c via the core Cc as described in relation to FIGS. 17 and 18; and then the optimum path (i.e. path with the fewest number of hops through Best Neighbours) will converge to the example shown in FIG. 19. While method 800 is directed to “pulling” knowledge of a destination node N that is not known by an originating node from the core Cc, it should now also be appreciated that where a new destination node Nc joins network 30c, that node Nc can also “push” knowledge of itself towards nodes at the core Cc, so that when method 800 is performed an originating node Nc can be sure that it will find information about the new/destination node Nc at core Cc. In the example given in FIG. 14, such a “push” of knowledge was not needed due to the performance criteria that automatically ensured that node N9c at core C would gain knowledge of node N14c. However, in other configurations of network 30c, a “push” of knowledge of nodes Nc at the core Cc can be desired. While only specific combinations of the various features and components of the present invention have been discussed herein, it will be apparent to those of skill in the art that desired subsets of the disclosed features and components and/or alternative combinations of these features and components can be utilized, as desired. For example, While the foregoing discussions contemplates substantially synchronous performance of method 200 by each node N (and its variants), it should be understood that such synchronous performance is not necessary and is used merely to simplify explanation. As another variation, each node N (and its variants) can also keep a separate record of all information that was sent to that node N (and its variants) by neighbouring nodes N (and its variants), even if that particular neighbouring node N (and its variants) was not chosen as the Best Neighbour for storage in that database D. This can allow that node N with its Best Neighbour removed to select its next Best Neighbour from the remaining neighbouring nodes N without having to rerun method 200, or otherwise wait for an update from all other remaining neighbour nodes. The present invention thus provides a novel system, method and apparatus for networking. Still further embodiments of the invention are contemplated and a review of certain of these embodiments will lead to further understanding of the invention. In the embodiments that follow, certain terms or concepts may differ somewhat from the previous section. Such differences are to be viewed as alternatives and/or supplements to the previous embodiments. In general, the network architecture of the present invention can enable individual nodes in the network to coordinate their activities such that the sum of their activities allows communication between nodes in the network. The principle limitation of existing ad-hoc networks used in a wireless environment networks is the ability to scale past a few hundred nodes, yet the network architecture and associated methods at least mitigate and in certain circumstances overcome prior art scaling problems. Exemplary embodiments thus follow in order to clarify understanding. These examples, when making specific reference to numbers, other parties' software or other specifics, are not meant to limit the generality of the method and system described herein. A person of skill in the art will be able to realize when two or more merged concepts could be separately implemented or useful, even if not explicitly described as such. Alternative embodiments should not be considered mutually exclusive unless specifically stated. In the following embodiments, the following terms are used: Nodes Each node in a network is directly connected to one or more other nodes via a link. A node could be a computer, network adapter, switch, wireless access point or any device that contains memory and ability to process data. However, the form of a node is not particularly limited. Links A link is a connection between two nodes that is capable of carrying information. A link between two nodes could be several different links that are ‘bonded’ together. A link could be physical (wires, etc), actual physical items (such as boxes, widgets, liquids, etc), computer buses, radio, microwave, light, quantum interactions, sound, etc. A link could be a series of separate links of varying types. However, the form of a link is not particularly limited. Calculation of Link Cost ‘Link Cost’ is a value that allows the comparison between two or more links. In this document the lower the ‘link cost’ the better the link. This is a standard approach, and someone skilled in the art will be aware of possible variations. Link cost is a value that is used to describe the quality of the link. The link cost for the link can be based on (but not limited to): 1. line quality 2. uptime 3. link consistency 4. latency 5. bandwidth 6. signal to noise ratio 7. remaining battery power on the node The link cost will be able to change over time as the factors that is it based on change. Persons skilled in the art will be able to assign link costs, or create a dynamic discovery mechanism. It is suggested that the assignment of link costs is consistent across the network. For example two identical links in different parts of the networks should have the same or similar link costs. It is suggested that the link cost of a pipe has an approximately direct relationship to its quality. For example, a 1 Mbit pipe should have 10 times the link cost of 10 Mbit pipe. These link costs will be used to find the best path through the network using a Dykstra like algorithm An alternative embodiment involves randomly varying the calculated link cost by a small random amount that does not exceed 1% (for example) of the total link cost. Node Names Each node in the network has a unique name. This unique name could be: 1. Generated by the node. 2. Assigned prior to node activation. 3. Requested from a central location by the node in a manner similar in result to a DHCP (Dynamic Host Configuration Protocol) server. If a node was to request a name from a central location using this described network, it would first pick a random unique name and use that name to request a name from the central location. A node may keep its name permanently, or may generate a new name on startup or any time it wants to. Node A can send a message to node B if node A knows the name of node B. A node may have multiple names in order to emulate several different nodes. For example a node might have two names: ‘Print_Server’ and ‘File_Server’. A node may generate new a name for each new connection that is established to it. Ports are discussed as a destination for messages, however the use of ports in these examples is not meant to limit the invention to only using ports. A person skilled in the art would be aware of other mechanisms that could be used as message destinations. For example, nodes could generate a unique name for each connection. Usually nodes should have a unique name. An alternative embodiment would allow a node to share a name with another node or nodes in the network. This will be discussed in detail later. There is no limitation implied by the inventors as to the number of names a node has, how often it adds or removes names, what the name is, or if it tells anyone about the name or names that it has selected. For the sake of clarity in this document we assume that each node has only one unique name associated with it. This should not be seen as limiting the scope of this invention. A node may share the same name as one or more other nodes in the network. Establishing Connections Between Nodes If a link is able be established between two nodes and these nodes wish to establish a link then nodes will need to exchange some information to establish that connection. This information may include version numbers, etc. Alternative embodiments could include the exchanging of a ‘tie-breaker’ number that will allow a node to choose between to otherwise equal links. It is suggested that the same tie-breaker value is given to all directly connected nodes. If a node A tells node B that it has already seen an equivalent tie-breaker number from some other node then node B will need to pick a new tie-breaker number and send it to all of its directly connected nodes. This process is illustrated in FIG. 20. The request for a new tie-breaker number might look like this (for example): struct sRequestNewTieBreaker { // This structure is empty, if the node sees this message it will // generate a new tie breaker value and tell all its directly connected // nodes this new value } Alternative embodiments could include a maximum count of nodes that this node wants to know about. For example, if node A has limited memory it would tell node B to tell it about no more then X different nodes. Alternative embodiments could include exchanging of link costs for the link that was used to establish the connection. If the link cost changes during the operation of the network a node may send a message to its directly connected node on the other end of the link that the link cost has changed. If link costs are exchanged, nodes may agree on the same link cost or may still pick different link costs, indicating an asymmetrical connection. If all three previous alternative embodiments were included the message exchanged would look like this (for example): struct sIntroMessage { // the number used to break ties int uiTieBreakerNumber; // the maximum number of destination nodes // this node wants to know about. int uiNodeCapacityCount; // the link cost for the connection between these two nodes float fLinkCost; } FIG. 21 is a flowchart of initialization process. A connection is assumed to be able to deliver the messages in order and error free. If this is not possible is it assumed that the connection will be treated as ‘failed’. The Spread of Node Knowledge In order for node A to send a message to node B, node A needs to know the name of node B as well as the directly connected node or link that is the next best step to get to node B. If node A or node B wants another node to send them messages then they have to tell at least one directly connected node about their name. When a node has established a link to another node it can start sending node information. Node information includes the name of the node and the cumulative link cost to reach that node. When the network is just turned on, no node knows about the names of any other node except itself, thus the initial cumulative link cost for the nodes that it knows about (itself) would be 0. When a node receives knowledge of another node A from link L it will add the link cost of the link L to the cumulative link cost it was told for node A and store that information associated with the link L in database D. When the link cost for node A that was received from connection L is referenced by this node from database D, it will implicitly include the link cost for that link L that was added to it. Each node stores the information that it has received from each link. A node does not need to know the name of the node on the other end of the link. All it needs to do is record the knowledge that the node on the other end of the link is sending it. A node will store all the node updates it has received from neighbour nodes. When a node N has received knowledge of node B from a link it will compare the cumulative link costs for node B that it has received from other links. It will pick the link with the lowest cumulative link cost as its “Best Neighbour” for the messages flowing to node B. When a node N sends an update for node B to its directly connected nodes it will tell them the name of the node and the lowest cumulative link cost that it has received from its directly connected nodes. Cumulative link cost is additive. FIG. 22 demonstrates this additive property. This process continues until knowledge of the node has spread through the entire network and each node has selected one link as having the lowest cumulative link cost. This process is very similar to Dykstra's algorithm, or the Bellman-Ford algorithm for finding the shortest path through a network. Someone skilled in the art will recognize such approaches, and the variations that yield a similar result. FIGS. 23-26 show the flow of node knowledge through a network. All the links are assumed to have cost of one. This is considered to be an example only and in no way is meant to limit the generality of this invention. For example, links may have different link costs, and the number of nodes and their specific interconnections may be infinitely varied. At no point does a node need to build a global view of the network topology. A node is only aware of node knowledge its directly connected neighbor nodes have told it. This type of network might be compared to a distance vector network by someone skilled in the art. An alternative embodiment could use the tie-breaker number (discussed earlier) to pick between two or more links with the lowest cumulative link cost. The structure for message that spreads node knowledge might look like this (for example) struct sNodeKnowledge { Name NameOfTheNode; Float fCumulativeLinkCost; } The fCumulativeLinkCost should be set to zero on the node with that particular name. Alternative embodiments could have the fCumulativeLinkCost set to non-zero on the node with that particular name. This could be used to disguise the true location of a destination node. Setting the fCumulativeLinkCost to non-zero on the node with that particular name (for example 50) will not affect the convergence of the network. Link Cost Changes If a link cost changes then the node will need to need to take the difference between the new link cost and the old link cost and add it to the cumulative link cost for all node information that has been received from that link. Below is exemplary pseudo code that shows how cumulative link cost can be adjusted for each node update that was received from the link that changed its link cost. CumualtiveLinkCost=CumualtiveLinkCost+(NewLinkCost−OldLinkCost); If (CumualtiveLinkCost>INFINITY)CumualtiveLinkCost=INFINITY; On the basis of this change it will also re-evaluate its choice of ‘Best Neighbour’. It will also need to tell its neighbors about any nodes where the lowest cumulative link cost for a particular destination node changed. For example, if the link cost for a link that was not chosen as a ‘Best Neighbour’ for a destination node A changes, and after the change that link is still not chosen as a ‘Best Neighbour’ for destination node A, then the cumulative link cost would remain the same for node A and no updates would need to be sent to directly connected nodes. Link Removal (if a Link is Removed) This can be looked at the same way as the link cost for that link going to infinity. For each destination node that was using this link as it ‘Best Neighbour’ the next best ‘non-infinity’ alternative for will be selected. If there is no such alternative then no ‘Best Neighbour’ can be selected and all directly connected nodes will be told a cumulative link cost of infinity for those nodes. If no ‘Best Neighbour’ is selected then messages destined for those nodes will not be able to sent. Large Networks In large networks with a large variation in interconnect speed and node capability different techniques need to be employed to ensure that any given node can connect to any other node in the network, even if there are millions of nodes. Using the original method, knowledge of a destination node will spread quickly through a network. The problem in large networks is three fold: 1. The bandwidth required to keep every node informed of all destination nodes grows to a point where there is no bandwidth left for data. 2. Bandwidth throttling on destination node updates used to ensure that data can flow will slow the propagation of destination node updates greatly. 3. Nodes with not enough memory to know of every node in the network will be unable to connect to every node in the network, and may also limit the ability of nodes with sufficient resources to connect to every node in the network. A solution is found by introducing the idea of the ‘core’ or center of the network. The core of the network will most likely have nodes with more memory and bandwidth then an average node, and most likely to be centrally located topologically. Since this new network system does not have any knowledge of network topology, or any other nodes in the network except the nodes directly connected to it, nodes can only approximate where the core of the network is. This can be done by examining which link is a ‘Best Neighbour’ for the most destination nodes. A directly connected link is picked as a ‘Best Neighbour’ for a destination node because it has the lowest cumulative link cost. The lowest link cost will generally be provided by the link that is closest to the ultimate destination node. If a link is used as a ‘Best Neighbour’ for more destination nodes then any other link, then this link is considered a step toward the core, or center of the network. An alternative embodiment could be the node making a decision as to the next best step to some other node or beacon, and use this as its ‘next best step to the core’. An alternative embodiment could be the node using some combination of factors to determine what its ‘next best step to the core’ is. These factors could some combination of (although not limited to): 1. Radio direction finding of some target beacon 2. GPS position co-ordinates, and the next best step to some location 3. A special marker node or nodes. 4. Other externally measurable factors A node does not need to know where the center of the network is, only its next best step the center of the network. A core can be defined as when two nodes select each other as their next best step towards the core. There is nothing special about the core, the two nodes that form the core act as any other nodes in the network would act. If there is a tie between a set of directly connected nodes for who was picked as the ‘Best Neighbour’ for the most destination nodes, the directly connected node with the highest ‘tie-breaker’ value (which was passed during initialization) will be selected as the next best step towards the core. This mechanism will ensure that there are no loops in a non-trival network (besides Node A->Node B->Node A type loops). If this tie-breaker embodiment is not used, then a random selection can be made. This idea of using a nodes ‘next best step to the core’ forms a hierarchy. This hierarchy can be used to push specific node knowledge up the hierarchy to the top of the tree. The HSPP's (discussed later) exploit this hierarchy to push (or pull) node knowledge up and down this hierarchy. FIG. 54 is an example of network where each node has selected a directly connected node as its next best step to the core. The network is then rearranged to better show the nature of the hierarchy that is created. As the network topology changes so will the hierarchy that is formed. Detecting an Isolated Core An alternative embodiment that helps in the detection of ‘isolated cores’. A core is defined as two directly connected nodes that have selected each other as the next best to the core. FIG. 27 illustrates and example of this. When a node has chosen a directly connected node as its ‘next best step to the core’ it will tell that directly connected node of its choice. This allows nodes to detect when they have generated a core that no other nodes are using as their core. The message that is passed can look like this: struct sCoreMessage { bool bIsNextStepToCore; } If a core is created, both nodes that form the core (in this example Node A and Node B) will check to see how many directly connected nodes they have. If there is more then one directly connected node then they kill examine all the other directly connected nodes. If the only directly connected node that has chosen this node as its next best step to the core is the node that has caused the core to be created, then this node will select its next best choice to be the next best step to the core. This can help eliminate cores that can block the flow of knowledge to the real core. Exemplary Alternative Ways to Select the Next Best Step to the Core The approach discussed previously involved assigning a credit of ‘1’ to a directly connected node for each destination node that selects that directly connected node as a ‘Best Neighbour’. The node with the highest count is the next best step to the core (or in the case of an isolated core, the second highest count). If any embodiment uses multiple ‘Best Neighbours’ (such as multipath discussed later), then each ‘Best Neighbour’ chosen for each destination node could be assigned the appropriate credit. Alternatively, only that ‘Best Neighbour’ with the best latency (in the case of multipath) could be assigned the credit. Instead of assigning a credit of one to each directly connected node for each destination node that selects it as its best choice, other values can be used. For example, log(fCumulativeLinkCost+1)*500 can be the credit assigned. Other metrics could also be used. This metric has the advantage of giving more weight to those destination nodes that are further away. In a dense mesh with similar connections and nodes, this type of metric can help better, more centralized cores form. Another possible embodiment which can be used to extend the idea of providing more weighting to destination nodes that are further away is to order all destination nodes by their link costs, and only use the x % (for example, 50%) that are the furthest away to determine the next best step to the core. Another embodiment can use a weighting value assigned to each node. This weight could be assigned by the node that created the name. For example, if this weighting value was added to the node update structure it would look like this: struct sNodeKnowledge { Name NameOfTheNode; Float fCumulativeLinkCost; Int nWeight; } The nWeight value (that is in the sNodeKnowledge structure) can be used to help cores form near more powerful nodes. For example the credit assigned could be multiplied by 10ˆnWeight (where 10 is an example). This will help cores form near the one or two large nodes, even if they are surrounded by millions of very low power nodes. The nWeight value should be assigned in a consistent fashion across all nodes in the network. Possible nWeight values for types of nodes: Equivilant to X low nWeight value Type of Node capacity sensors 0 A very low capacity sensor 1 or mote 1 A bigger sensor 10 2 A bigger sensor with more 100 battery life and memory 3 A cell phone 1000 10 A home computer 10000000000 15 A core router 1000000000000000 20 A super computer with 100000000000000000000 massive connectivity and memory These weight values are suggestions only, someone skilled in the art would be able to assign suitable values for their application. Next Step to the Core in a Network with Asymetric Link Costs This is an alternative embodiment for choosing the next best step to the core. If link is given an asymmetric cost, for example the link L that joins nodes A and B has a cost of 10 when going from A to B and a cost of 20 when going from B to A then an alternative embodiment is useful to help the core form in a single location in the network. In an earlier embodiment the nodes agree on the link cost for a particular link and used their ‘Best Neighbour’ selection based on this shared link cost. If asymmetric link costs are used to determine the ‘Best Neighbour’, then using symmetric link costs can be used to choose the next step to the core. Using symmetric link costs can help ensure that a core actually forms. For each node that a node knows about it will decide which link is its next best step to reach that node. It chooses this next best step based on cumulative link cost, and perhaps a tie-breaker number. This ‘Best Neighbour’ is then given a credit that will be summed with the other credits assigned to it. The ‘Best Neighbour’ with the most credit will be picked as the next best step to the core. In this alternative embodiment a node will agree with the node it is linked to on an alternative cost for the link. This alternative link cost will be the same for both nodes. This alternative link cost will be used to adjust the cumulative link cost. A choice for ‘Best Neighbour’ will be made with this alternative cumulative link cost. This ‘Best Neighbour’ will be assigned the credit that goes towards picking it as the next best step to the core, even if it was the not ‘Best Neighbour’ picked as the next best step to the actual node. This equation describes how the alternative cumulative link cost can be calculated. AlternativeCumulativeLinkCost=ActualCumulativeLinkCost+(AlternativeLinkCost−ActualLinkCost) High Speed Propagation Path(s) (“HSPP”) Since nodes not at the core of the network will generally not have as much memory as nodes at the core, they may forget about a node N that relies on them to allow others to connect to node N. If these nodes did forget, no other node in the network would be able to connect to that node N. In the same way, a node that is looking to establish a connection with a node Q faces the same problem. The knowledge of node Q that it is looking for won't reach it fast enough—or maybe not at all if either node Q or the node that is trying to connect to it is surrounded by low capacity nodes. An approach is to use the implicit hierarchy created by each nodes choice as to its ‘next best step to the core’. Node knowledge is pushed up and down this hierarchy to the core. This allows efficient transfer of node knowledge to and from the center of the network. Node knowledge can be pushed/pulled using a methodology referred to herein as a High Speed Propagation Path (“HSPP”). An HSPP can be thought of as a marked path/paths between a node and the core. Once that path has been set up it is maintained until the node that created it has been removed. There are two types of HSPP's. the first is a notify HSPP. The Notify HSPP pulls knowledge of a particular node towards the core. Nodes that have an HSPP ruming through them are not allowed to forget about that node that is associated with the HSPP. All nodes create a Notify HSPP to drive knowledge of themselves towards the core. A request HSPP is only created when node is looking for knowledge of another node. The request HSPP operates in the identical way to the notify HSPP except that instead of pulling knowledge towards to the core it pulls knowledge back to the node that created it. (Persons skilled in the art will appreciate that, in the context of an HSPP, the terms “push” and “pull” are useful for illustrative purposes, but can be viewed as somewhat artificial terms, since in effect, an HSPP improves the ‘rank’ of a node in a node database so that knowledge of that node is sent before the knowledge of other nodes.) An HSPP travels to the core using each nodes next best step the core. Each nodes ‘next best step to the core’ creates an implicit hierarchy. An HSPP is not a path for user messages itself, rather it forces nodes on the path to retain knowledge of the node or nodes in question, and send knowledge of that node or nodes quickly along the HSPP. It also raises the priority of updates for the node names associated with the HSPP. This has the effect of sending route update quickly towards the top of this implicit hierarchy. The HSPP does not specify where user data messages flow. The HSPP is only there to guarantee that there is always at least one path to the core, and to help nodes form an initial connection to each other. Once an initial connection has been formed, nodes no longer need to use the HSPP. An HSPP may be referenced as belonging to one node name, or being associated with one node name. This in no way limits the number, or type of nodes that an HSPP may be associated with. In this embodiment the name of the HSPP is the usually the name of the node that the HSPP will be pushing/pulling to/from the core. An HSPP is tied to a particular node name or class/group of node names. If a node hosts an HSPP for a particular destination node it will immediately process and send node knowledge of any nodes that are referenced by that HSPP. Node knowledge in the case can be viewed as a sNodeKnowledge update (for example). An alternative embodiment could limit that processing to: 1. Initial knowledge of the destination node 2. When the destination node fCumulativeLinkCost goes to infinity 3. When the destination node fCumulativeLinkCost moves from infinity to some other value This can ensure that all nodes in the HSPP will always know about the nodes referenced by the HSPP if any one of those nodes can ‘see’ the node or nodes referenced by the HSPP. Node knowledge is not contained in the HSPP. The HSPP only sets up a path with a very high priority for knowledge of a particular node or nodes. This means that node updates for those nodes referenced by the HSPP will be immediately sent. An HSPP is typically considered a bi-direction path. Alternative embodiments can have two types of types of HSPP's. One type pushes knowledge of a node towards the core. This type of HSPP could be called a notify HSPP. The second pulls knowledge of a node towards the node that created the HSPP. This type of HSPP could be called a request HSPP. When a node is first connected to the network, it can create an HSPP based on its node name. This HSPP will push knowledge of this newly created node towards the core of the network. The HSPP created by this node can be maintained for the life of the node, or for as long as the node wants to maintain the HSPP. If the node is disconnected or the node decides to no longer maintain the HSPP, then it will be removed. An alternative embodiment could have this HSPP be a ‘push HSPP’ instead of a bi-directional HSPP. If a node is trying to connect to another node N, it will create an HSPP that references that node N. This HSPP will travel to the core and help pull back knowledge of node N to the node that created the HSPP and wants to connect to node N. An alternative embodiment could have this HSPP be a ‘pull HSPP’ instead of a bi-directional HSPP. If the node no longer wants to maintain an HSPP (perhaps because the connection to node N is no longer needed) it can send an HSPP update with ‘bActive’=false to all the directly connected nodes that it sent the original HSPP with bActive=true. This should only be done by the node that has created the HSPP. Alternative embodiments could allow the request HSPP to be maintained by the node that generated the request HSPP after the connection has been dropped for some amount of time, in order to facilitate faster re-connects. Both types of HSPP will travel to the core. The HSPP that sends knowledge of a node to the core can be maintained for the life of the node. The request HSPP will probably be maintained for the life of the connection. An alternative embodiment has nodes that create an HSPP send that HSPP to all directly connected nodes, instead of only to their next best step to the core of the network. This embodiment allows the network to be more robust while moving and shifting. An alternative embodiment includes making sure that a node will not send a directly connected node more HSPP's then the maximum nodes requested by that directly connected node. An HSPP does not specify where user data should flow, it only helps to establish a connection (possibly non-optimal) between nodes, or one node and the core. An HSPP will travel to the core even if it encounters node knowledge before it reaches the core. Alternative embodiments can have the HSPP stop before it reaches the core. How an HSPP is Established and Maintained If a node is told of an HSPP it remembers that HSPP until it is told to forget that about that HSPP, or the connection between it and the node that told it of that HSPP is broken. In an embodiment where a node limits the number of nodes it wants to be told about, that node stores as many HSPP's as are given to it. A node should not send more HSPP's to a directly connected node then the maximum destination node count that directly connected node requested. In certain systems the amount of memory available on nodes will be such that it can assumed that there is enough memory, and that no matter how many HSPP's pass through a node it will be able to store them all. This is even more likely because the number of HSPP's on a node will be roughly related to how close this node is to the core, and a node is usually not close to a core unless it has lots of capacity, and therefore probably lots of memory. UR=Ultimate Receiver Node US=Ultimate Sender Node An HSPP takes the form of: struct sHSPP { // The name of the node could be replaced with a number // (discussed later). It may also represent a class of nodes // or node name. sNodeName nnName; // a boolean to tell the node if the HSPP is being // activated or removed. bool bActive; // a boolean to decide if this a UR (or US generated HSPP) bool bURGenerated; }; In these descriptions an HSPP H is considered to be called HSPP H regardless of what bActive or bURGenerated (more generally the HSPP Type) are. The HSPP H can derive its name from the node name that it represents. An alternative embodiment might be where the name of HSPP H is not linked to the node name (or names) it references. The HSPP structure in this embodiment might look like this (for example): struct sAlternateHSPP { // a unique name to represent this HSPP sHSPPName HSPPName; // The name of the node could be replaced with a number // (discussed later). It may also represent a class of nodes // or node name. sNodeName nnName; // a boolean to tell the node if the HSPP is being // activated or removed. bool bActive; // a boolean to decide if this a UR (or US generated HSPP) bool bURGenerated; }; The following description uses sHSPP (as oppose to sAlternateHSPP) in order to describe how HSPP's work. This should not be seen as limiting the generality of the method. A UR generated HSPP can also be called a ‘Notify HSPP’ and a US generated HSPP can also be called a ‘Request HSPP’. It is important that the HSPP does not loop back on itself, even if the HSPP's path is changed or broken. This should be guaranteed by the process in which the next step to the core of the network is generated. A node should never send an active HSPP H (bActive=true) to a node that has sent it an active HSPP H. A node will record the number of directly connected nodes that tell it to maintain the HSPP H (bActive is set to true in the structure). If this count drops to zero it will tell its directly connected nodes that were sent an active HSPP H (bActive=true), an inactive HSPP H (bActive=false). At a broad level the HSPP finds a non-looping path to the core, and when it reaches the core it stops spreading. It does this because the two nodes that form the core will select each other as their next best step towards the core. And since an active HSPP will not be sent to a node that has already sent it an active HSPP the HSPP will only be sent by one node of the two node core. If the HSPP path is cut, the HSPP from the cut to the core will be removed. It will be removed because the only node that told it an active HSPP will be removed. This will prompt the node on the core side of the cut to tell those nodes that it told an active HSPP H an inactive HSPP H. In most cases this process will cascade towards the core removing that active HSPP. An HSPP will travel to the core using each nodes next best step to the core. The purpose of the HSPP generated by the UR is to maintain a path between it and the core at all times, so that all nodes in the system can find it by sending a US generated HSPP (a request HSPP) to the core. If a node N receives an active HSPP H from any of its directly connected nodes, it will send on an active HSPP H to the node (or nodes) selected as its next best step to the core, assuming that that node (or nodes) that has been selected as its next best step to the core has not sent it an active HSPP H. If multiple active HSPPs H arrive at the same node, that node will send on an HSPP with bURGenerated marked as true, if any of the incoming HSPP's have their bURGenerated marked as true. If the directly connected node that was selected as the next best step to the core changes from node A to node B, then all the HSPP's that were sent to node A will be sent to node B instead (assuming that the next ‘best step to the core’ has not sent this node an active HSPP of the same name already). Those HSPP's that were sent to node A will have an HSPP update sent to node A with their ‘bActive’ values set to false, and the ones sent to node B will have their ‘bActive’ values set to true. An alternative embodiment is if node A creates an HSPP it should send the HSPP to all directly connected nodes. This ensures that even if this node is moving rapidly, that knowledge is always driven to or from the core. When a node A establishes a connection to another node B, Node A can use an HSPP to pull route information for node B to itself (called a request HSPP). This HSPP should also be sent to all directly connected nodes. An alternative embodiment has only one type of HSPP that moves data bi-directionally. This type of HSPP would be able to replace both a push/notify HSPP and a pull/request HSPP. In this embodiment that bURGenerated parameter is omitted. An HSPP does not need to be continually resent. Once an HSPP has been established in a static network, no addition HSPP messages need to be sent. This will be apparent to someone skilled in the art. Each node remembers which directly connected nodes have told it about which HSPP's, a node also typically remembers which HSPPs it has told to directly connected nodes. Alternative HSPP Types This alternative embodiment can help maintain connection in a low bandwidth environment. In the previous embodiment there are two types of HSPP: 1. Notify HSPP 2. Request HSPP This embodiment will introduce a new type of HSPP called a ‘Priority Notify HSPP’. The ‘Priority Notify HSPP’ is the same as ‘notify HSPP’ except that it will be sent before all ‘Notify HSPP's’. This will be discussed later. For example, if a node is attempting to communicate with another node, or is aware that another node is attempting to communicate with it, then it can change its notify HSPP's into ‘Priority Notify HSPP's’. The following table describes what type of HSPP a node will send to its next best step to the core, given the types of HSPP's it receives for a particular destination node. HSPP's In HSPP Out Request HSPP Request HSPP Notify HSPP Notify HSPP Priority HSPP Priority Notify HSPP Request HSPP + Notify HSPP Notify HSPP Request HSPP + Priority Notify HSPP Priority Notify HSPP Request HSPP + Priority Notify HSPP Notify HSPP + Priority Notify HSPP + Notify HSPP + Priority Notify HSPP Priority Notify HSPP If the entries that contain ‘Priority Notify HSPP’ are ignored, this will also describe how the other embodiment decides which HSPP type to send to its next best step to the core. The HSPP structure might be amended to look like this: struct sHSPP { // The name of the node could be replaced with a number // (discussed previously) sNodeName nnName; // a boolean to tell the node if the HSPP is being // activated or removed. bool bActive; // the HSPP Type (for ex: Request HSPP, Notify HSPP, // Priority Notify HSPP) int nHSPPType; }; Ordering HSPP's to be Sent An alternative embodiment adjusts the order that HSPP's are sent. When a node receives an HSPP it will need to order it before sending. This will ensure that a more important HSPP's are sent first. The order that HSPP's should be sent if the ‘Priority Notify HSPP’ embodiment is not used is: 1. Request HSPP 2. Notify HSPP If the ‘Priority Notify HSPP’ embodiment is used then the order is this: 1. Request HSPP and Priority Notify HSPP 2. Notify HSPP Removing Simple Loops This alternative embodiment can be used to stop simple loops from forming. Someone skilled in the art will recognize the variations on the ‘poison reverse’. A node A that has picked node B as a ‘Best Neighbour’ for messages going to node N then node A will tell node B that it has been picked. For example, node A could send node B a message that looks like this: struct sIsBestNeighbour { Name NodeName; Boolean bIsBestNeighbour; } If node A has told node B that it is the ‘Best Neighbour’ for messages going to node N then node B will be unable to pick node A as the ‘Best Neighbour’ for messages going to node N. If the only possible choice node B has for messages going to node N is node A then B will select no ‘Best Neighbour’ and set its cumulative link cost to node N to infinity. Marking Nodes as in the Data Stream This alternative embodiment can be used to mark those nodes that are in the data stream. In this embodiment a node is only considered as ‘in the data stream’ if it is marked as ‘in the data stream’. A node may forward payload packets without being marked in the data stream. If a node is forwarding payload packets, but is not marked in the data stream it is not considered as ‘in the data stream’. If a node A has attempted to establish a data connection to another node N in the network it will tell the node B that it has selected as its ‘Best Neighbour’ to node N that node B is a ‘Best Neighbour’ for node N and it is in the data stream for node N. If a node B has been told that it is in the data stream by a directly connected node that has told B that it is a ‘Best Neighbour’ then node B will tell the directly connected node C that it has selected as a ‘Best Neighbour’ for node N that node C is in the data stream. As an example the structure of this message might look like this: struct sInTheDataStream { Name NodeName; Boolean bIsInTheDataStream; } If node B was marked as in the data stream for messages going to node N it would tell the node that it has selected as its next best step to node N that it is in the data stream. If node B is no longer marked as in the data stream because: 1. The directly connected node (or nodes) that had told node B that it was in the data stream disconnected. 2. The directly connected node (or nodes) that told node B that it was in the data stream all told node B that it was no longer in the data stream. Then node B will tell its ‘Best Neighbour’ C. that it is no longer in the data stream. A node is only marked as being the data stream by this flag. A node may forward message packets without being marked as in the data stream. Link Cost from Stream The term ‘link cost from stream’ is sometimes referred to herein as ‘hop cost from flow’. This alternative embodiment can be used to order the node updates in a network. This ordering allows the network to become much more efficient by sending updates to maintain and converge data flows before other updates. The sNodeKnowledge structure used to pass node knowledge around might be modified to look like this: (for example) struct sNodeKnowledge { Name NameOfTheNode; Float fCumulativeLinkCost; Float fCumulativeLinkCostFromStream; } The fCumulativeLinkCostFromStream is incremented in the same way as the fCumulativeLinkCost. However, if a node is in the data stream for a particular node it will reset the fCumulativeLinkCostFromStream to 0 before sending the update to its directly connected nodes. Just as the fCumulativeLinkCost is initialized to zero the fCumulativeLinkCostFromStream is also initialized to zero. An alternative embodiment could have the fCumulativeLinkCostFromStream reset for other reasons as well such as user data messages being passed through that node. Someone skilled in the art will recognize such variations. An alternative embodiment to help in low bandwidth environments is to have nodes set their fCumulativeLinkCostFromStream to a non-zero value (for example 50) if they are not exchanging user data with another node. If they are in communication with another node they would set their fCumulativeLinkCostFromStream to 0. An alternative embodiment could also set a non-zero fCumulativeLinkCostFromStream to a multiple of the min, max, average (etc) of the link costs associated with the links that this node has established. If the fCumulativeLinkCost goes to infinity, then keep the last non-infinity fCumulativeLinkCostFromStream value. This will be used to order when to send the infinity update to directly connected nodes. Alternative Link Cost from Stream This embodiment is similar to the previous embodiment, except that it is more useful in helping the network remove node knowledge. In the previous embodiment the fCumulativeLinkCostFromStream got reset to zero when it came across a node that was marked as in the data stream. This embodiment changes what type of update will be sent. If a node A that created the destination node E (this could also be described as a node A that created a node name E for use by node A) is told by a directly connected node B that it is in the data stream for node E then node A will tell that directly connected node B a node update for node E where the fCumulativeLinkCostFromStream=fCumulativeLinkCost. In most cases this will have both these values set to zero since node A has created the name E. All other directly connected nodes that have not told node A that it is in the data stream will be told a fCumulativeLinkCostFromStream !=fCumulativeLinkCost. For example: fCumulativeLinkCostFromStream=fCumulativeLinkCost+0.1f; Since fCumulativeLinkCost is usually zero these directly connect nodes would be told a fCumulativeLinkCostFromStream of 0.1 and a fCumulativeLinkCost of 0. 0.1 should be viewed as exemplar only. If a node that is not the node that created the destination node name (in this example it would be any node except node A) is marked as ‘in the data stream’ and has a fCumulativeLinkCostFromStream==fCumulativeLinkCost then it will tell all its directly connect nodes that have not marked it in the data steam an update for node E with the fCumulativeLinkCostFromStream==0. For those nodes that have marked it as in the data stream it will tell them an update for node E with fCumulativeLinkCostFromStream==fCumulativeLinkCost. At no point in this embodiment is the fCumulativeLinkCost adjusted to match fCumulativeLinkCostFromStream. The fCumulativeLinkCostFromStream is always adjusted relative to the fCumulativeLinkCost. Ordering of Node Updates In a large network there can be a lot of node updates to send. This alternative embodiment allows updates be ordered by how important they are. This alternative embodiment assumes that fCumulativeLinkCostFromStream is used and that HSPP's are used. If only one of them are used then just ignore the ordering that un-used embodiment would provide. All nodes in the system are ordered by the fCumulativeLinkCostFromStream value that was sent to it by the selected ‘Best Neighbour’ (the link cost for the connection was added to the value sent by the directly connected node). This ordered list could take the form of a TreeMap (in the example of Java). If the previous embodiment is used then when fCumulativeLinkCost=fCumulativeLinkCostFromStream and a node is marked in the data stream then it should be added to the treemap as if it had a fCumulativeLinkCostFromStream of 0. When an update to a destination node route needs to be sent to a directly connected node this destination node is placed in a TreeMap that is maintained for each directly connected node. The TreeMap is a data structure that allows items to be removed from in by ascending key order. This allows more important updates to be sent to the directly connected node before less important updates. The destination nodes placed in this TreeMap are ordered by their fCumulativeLinkCostFromStream values, except in the case where: 1. This node is in the path of an HSPP for this destination node, and this directly connected node is: a. In the path to the core and the HSPP is a notify HSPP or if there is only one type of HSPP b. One of the nodes that told us of this HSPP and the HSPP is a request HSPP or there is only one type of HSPP. 2. This node is in the data stream for this destination node. (bIsInTheDataStream==true and fCumulativeLinkCost=fCumulativeLinkCostFromStream) If the destination node belongs to one of these two groups, the item is placed at the start of the ordered update list maintained for each directly connected node. Exemplar pseudo code for this process looks like this: float fTempCumLinkCostFStream = GetCumLinkCostFStream (NodeToUpdate); if (NodeToUpdate for this connection belongs to group 1 or 2) fTempCumLinkCostFStream = 0; while (CurrrentConnection.OrderedUpdateTreeMap contains fTempCumLinkCostFStream as a key) { IncrementfTempCumLinkCostFStream by a small amount } Add pair (fTempCumLinkCostFStream, NodeToUpdate) to CurrrentConnection.OrderedUpdateTreeMap; The destination node route updates are then sent in this order. When a destination update has been processed it is removed from this ordered list (CurrentConnection.OrderedUpdateTreeMap) This ordering insures that more important updates are sent before less important updates. The fTempCumLinkCostFStream should also be used on a per connection basis to determine which destination node updates should be sent. For example, if there are five destination nodes with fTempCumLinkCostFStream values of: 1.202—dest node D 1.341—dest node F 3.981—dest node G 8.192—dest node B 9.084—dest node M And the directly connected node has requested a maximum of four destination node routes sent to it, This node will only send the first four in this list (the node will not send the update for destination node M). If destination node G has its fTempCumLinkCostFStream change from 3.981 to 12.231 the new list would look like this: 1.202—dest node D 1.341—dest node F 8.192—dest node B 9.084—dest node M 12.231—dest node G In response this update this node would schedule an update for both destination node G and destination node M. The ordered pairs in CurrentConnection.OrderedUpdateTreeMap (assuming no HSPP's or Data Streams) would looks this: Position 1-(9.084,M) Position 2-(12.231,G) This node would then send an infinity update for node G. It would then schedule a delayed send for destination node M. (See ‘Delayed Sending’) An infinity destination node update makes sure that the messages needed to pass this information is sent for the node that is getting an infinity update. This example includes several different embodiments, for those that are not used someone skilled in the art will be able to omit the relevant item(s). a. fCumulativeLinkCost = INFINITY b. fCumulativeLinkCostFromStream = INFINITY c. bIsBestNeighbour = FALSE d. bIsInDataStream = FALSE When the update for destination node M is sent, it would be non-infinity. Delayed Sending This alternative embodiment helps node knowledge to be removed from the network when a node is removed from the network. If node knowledge is not removed from the network, then a proper hierarchy and core will have trouble forming. If this is the first time that a destination node update is being sent to a directly connected node, or the last update that was sent to this directly connected node had a fCumulativeLinkCost of infinity, the update should be delayed. For example, if the connection has a latency of 10 ms, the update should be delayed by (Latency+1)*2 ms, or in this example 22 ms. This latency should also exceed a multiple of the delay between control packet updates (see ‘Propagation Priorities) Someone skilled in the art will be able to experiment and find good delay values for their application. The exception is if either of these conditions are met: 1. This node is in the path of an HSPP for this destination node, and this directly connected node is: a. In the path to the core and the HSPP is a notify HSPP or there is only one type of HSPP. b. One of the nodes that told us of this HSPP and the HSPP is a request HSPP or there is only one type of HSPP. 2. This node is in the data stream for this destination node. (bIsInTheDataStream==true and fCumulativeLinkCost==fCumulativeLinkCostFromStream) If an infinity update has been scheduled to be sent (by having it placed in the CurrentConnection.OrderedUpdateTreeMap), but has not been sent by the time a non-infinity update is scheduled to be sent (because it has been delayed), the infinity must be sent first, and then a non-infinity update should be delayed again before being sent. Cycling a Destination Node from Infinity to Non-Infinity This alternative embodiment helps node knowledge to be removed from the network when a node is removed from the network. If any of these criteria are met for a node A update being sent to a directly connected node N: 1. If the alternative embodiment that limits the number of node updates that can be sent to a node is used: If the directly connected node N has been sent a non-infinity update for this destination node A, however the new fTempCumLinkCostFStream value (see above) for node A is greater then X other nodes' fTempCumLinkCostFStream value. Where X is the maximum number of nodes that the directly connected node N requested to be told about. 2. If the fTempCumLinkCostFStream for node A becomes the larger that any other nodes' fTempCumLinkCostFStream that was sent to this directly connected node N. This node will send the directly connected node N an update of infinity for this destination node A. Then after a suitable delay (See Delayed Sending) this node will send a non-infinity update for this destination node to the directly connected node, except in the case where this node A still meets criteria 1. This is part of the approach uses to help remove bad route data from the network, and automatically remove loops. An infinity update is an update with the fCumulativeLinkCost value set to infinity (see above for a more complete definition). The decision to send an infinity update (followed some time later with a non-infinity update for same destination node) when a destination node meets the previous criteria is a recommended approach. Alternative approaches to trigger the infinity update followed by the delayed non-infinity update are (but not limited to): 1. When the fTempCumLinkCostFStream increases by a certain percent, or amount in a specific period of time. For example, if the fTempCumLinkCostFStream increased by more then 10 times the connection cost in under 0.5 s. 2. When the position of this destination node in the ordered list moves more then (for example) 100 positions in the list, or moves more then (for example) 10% of the list in X seconds. Persons skilled in the art can determine a suitable increase in fTempCumLinkCostFStream and suitable timing values in order to trigger the infinity/non-infinity send. An alternative embodiment could use fCumulativeLinkCostFromStream instead of fTempCumLinkCostFStream. If a previously unknown destination node appears at the top of the list, the infinity does not need to be sent because the directly connected nodes have not been told a non-infinity update before. However, telling the directly connected nodes about this destination node should be delayed. This delayed sending does not need to occur if either on these conditions is met: 1. This node is in the path of an HSPP for this destination node, and this directly connected node is: c. In the path to the core and the HSPP is a notify HSPP or there is only one type of HSPP. d. One of the nodes that told us of this HSPP and the HSPP is a request HSPP or there is only one type of HSPP. 2. This node is in the data stream for this destination node. (bIsInTheDataStream==true and fCumulativeLinkCost==fCumulativeLinkCostFromStream) End User Software This network system and method can be used to emulate most other network protocols, or as a base for an entirely new network protocol. It can also serve as a replacement for the ‘routing brains’ of other protocols. In this document TCP/IP will be used as an example of a protocol that can be emulated. The use of TCP/IP as an example is not meant to limit the application of this invention to TCP/IP. In TCP/IP when a node is turned on, it does not announce its presence to the network. It does not need to because the name of the node (IP address) determines its location. In the present invention, the node needs the network to know that it exists, and provide the network with a guaranteed path to itself. This is discussed in much greater detail elsewhere. When end user software (“EUS”) wishes to establish a connection, it could do so in a manner very similar to TCP/IP. In TCP/IP the connection code looks similar to this: SOCKET sNewSocket=Connect(IP Address, port); With this invention, the ‘IP Address’ is replaced with a Globally Unique Identifier (“GUID”). SOCKET sNewSocket=Connect(GUID, port). In fact, if the IP Address can be guaranteed to be unique, then the IP address could serve as the GUID, providing a seamless replacement of an existing TCP/IP network stack with this new network invention. One way to guarantee a unique IP is to have each node create a random GUID and then use that to communicate with a DHCP (Dynamic Host Configuration Protocol) like server to request a unique IP address that can be used as a GUID. The node would then discard its first GUID name and use only this IP address as a GUID. Using IP addresses in this context would mean that IP addresses would not necessarily need to reflect a nodes position in the network hierarchy. Once a connection to a destination node has been requested, the network will determine a route to the destination (if such a route exists), and continually improve the route until an optimal route has been found. The receiving end will look identical to TCP/IP, except a request to determine the IP address of the connecting node will yield a GUID instead. (or an IP address is those are being used as GUIDs). This approach provides the routing through the network, someone skilled in the art could see how different flow control approaches might work better in different networks. For example, a wireless network might need an approach that does not lose packets when incoming data rates exceed outgoing connection rates. FIG. 28 is an example of where this routing method would fit into the TCP/IP example. Persons skilled in the art will appreciate that this new routing approach allows a TCP/IP like interface for end user applications. This is an example not meant to limit this routing approach to any particular interface (TCP/IP for example) or application. Connecting Two Nodes Across the Network The following is an example of one approach that can be used to connect two nodes in this network. This example (like all examples in this document) is not meant to limit the scope of the patent. Someone skilled in the art would be aware of many variations. If the alternative embodiment that uses HSPP's is not used then ignore the parts about HSPP's. If node A wishes to establish a connection with node B, it will first send out a request HSPP (discussed earlier) to all directly connected nodes. This request HSPP will draw and maintain route information about node B to node A. This request HSPP will be sent out even if node A already has knowledge of nod B. If the alternative embodiment that uses ‘priority notify hspp’ is used then node A can change its notify hspp to a priority notify hspp and inform all its directly connected nodes. This can help connectivity in low bandwidth mobile environments since it would allow nodes that are communicating to have their information spread before those nodes that are not communicating. This HSPP will travel to the core even if it encounters node route knowledge before reaching the core. Once Node A has a non-infinity, next best step to node B it will send out a ‘connection request message’ to the specified port on node B. This request will be sent to the directly connected node that has been selected as the ‘Best Neighbour’ for messages going to node B. If the ‘marking the data stream’ embodiment is used then node A will tell its directly connect node that it has selected as a ‘Best Neighbour’ that it is in the data stream for node B. The use of ports is for example only and is not meant to limit the scope of this invention. A possible alternative could be a new node name specifically for incoming connections. Someone skilled in the art would be aware of variations. It will keep sending this message every X seconds (for example 15 seconds), until a sConnectionAccept message has been received, or a timeout has been reached without reception (for example 120 seconds). The connection request message might contain the GUID of node A, and what port to send the connection reply message to. It may also contain a nUniqueRequestID that is used to allow node B to detect and ignore duplicate requests from node A. The connection request message looks like this (for example): struct sConnectionRequest { // the name of node A, could be replaced with a number // for reduced overhead. sNodeName nnNameA; // Which port on node A to reply to int nSystemDataPort; // Which port to send end user messages to on node A int nUserDataPort; // a unique request id that node B can use to // decide which duplicate requests to ignore int nUniqueRequestID; } When node B receives the ‘connection request’ message from node A it will generate a request HSPP for node A and send it to all directly connected nodes. This will draw and maintain route information about node A to node B. If the alternative embodiment that uses ‘priority notify hspp’ is used then node B can change its notify HSPP to a priority notify HSPP and inform all its directly connected nodes. This can help connectivity in low bandwidth mobile environments. If the alternative embodiment ‘in the data stream’ is used then Node B will wait until it sees where its next best step to node A is, and then mark the route to node A as ‘In the data stream’. Node B will then send a sConnectionAccept message to node A on the port specified (sConnectionRequest.nSystemDataPort). This message looks like this: struct sConnectionAccept { // the name of node B sNodeName nnNameB; // the port for user data on node B int nUserDataPortB; // the unique request ID provided by A in the // sConnectionRequest message int nUniqueRequestID; } The sConnectionAccept message will be sent until node A sends a sConnectionConfirmed message that is received by node B, or a timeout occurs. The sConnectionConfirmed message looks like this: struct sConnectionConfirmed { // the name of node A, could be replaced with a number // for reduced overhead. sNodeName nnNameA; // the unique request ID provided by A in the // sConnectionRequest message int nUniqueRequestID; } If a timeout occurs during the process the connection is deemed to have failed and will be dismantled. The request HSPP's that both nodes have generated will be removed, and the ‘in the data stream’ flag(s) will be removed (if they were added). Once the connection is established, both nodes may send user data messages to each others respective ports. These messages would then be routed to the end user software via sockets (in the case of TCP/IP). An alternative embodiment would not require a connection to be established, just the sending of EUS messages/payload packets when route to the destination node was located. Node Name Optimization and Messages This alternative embodiment can be used to optimize messages and name passing. Every node update and EUS message/payload packet needs to have a way to identify which destination node they reference. Node names and GUIDSs can easily be long, and inefficient to send with every message and node update. Nodes can make these sends more efficient by using numbers to represent long names. For example, if node A wants to tell node B about a destination node named ‘THISISALONGNODENAME.GUID’, it could first tell node B that: 1=‘THISISALONGNODENAME.GUID’ A structure for this could look like (for example): struct sCreateQNameMapping { // size of the name for the node int nNameSize; //name of the node char cNodeName[Size]; // the number that will represent this node name int nMappedNumber; }; Then instead of sending the long node name each time it wants to send a destination node update, or message—it can send a number that represents that node name (sCreateQNameMapping.nMappedNumber). When node A decides it no longer wants to tell node B about the destination node called ‘THISISALONGNODENAME.GUID’, it could tell B to forget about the mapping. That structure would look like: struct sRemoveQNameMapping { int nMappedNumber; }; Each node would maintain its own internal mapping of what names mapped to which numbers. It would also keep a translation table so that it could convert a name from a directly connected node to its own naming scheme. For example, a node A might use: 1=‘THISISALONGNODENAME.GUID’ And node B would use: 632=‘THISISALONGNODENAME.GUID’ Thus node B, would have a mapping that would allow it to convert node A's numbering scheme to a numbering scheme that makes sense for node B. In this example it would be: Node A Node B 1 632 . . . . . . . . . . . . Using this numbering scheme also allows messages to be easily tagged as to which destination node they are destined for. For example, if the system had a message of 100 bytes, it would reserve the first four bytes to store the destination node name the message is being sent to, followed by the message. This would make the total message size 104 bytes. An example of this structure also includes the size of the message: struct sMessage { // the number that maps to the name of the node where // this message is being sent to int uiNodeID; // the size of the payload packet int uiMsgSize; // the actual payload packet char cMsg[uiMsgSize]; } When this message is received by a node, that node would refer to its translation table and convert the destination mapping number to its own mapping number. It can then use this mapping number to decide if this node is the destination for the payload packet, or if it needs to send this payload packet to another directly connected node. These quick destination numbers could be placed in a TCP/IP header by someone skilled in the art. When to Remove Name Mapping This alternative embodiment is used to help remove name mappings that are no longer needed. If a destination node has a fCumulativeLinkCost of infinity continuously for more then X ms (for example 5000 ms) and it has sent this update to all directly connected nodes, then this node will remove knowledge of this destination node. First it will release all the memory associated with this destination node, and the updates that were provided to it by the directly connected node. It will also remove any messages that this node has waiting to send to that destination node. Next it will tell its directly connected nodes to forget the number->name mapping for this destination node. Once all of the directly connected nodes tell this node that it too can forget about their number->name mappings for this destination node, then this node can remove its own number->name mapping. At this stage there is no longer any memory associated with this destination node. A node should attempt to reuse forgotten internal node numbers before using new numbers. Simpler Fast Routing This alternative embodiment is used to speed up the routing of packets. An optimization would be add another column to the name mapping table indicating which directly connected node will be receiving the message: Thus node B, would have a mapping that would allow it to convert node A's numbering scheme to a numbering scheme that makes sense for node B. In this example it would be: Directly Connected Node Node A Node B Message is Being Sent To 1 632 7 . . . . . . . . . . . . This allows the entire routing process to be one array lookup. If node A sent a message to node B with a destination node 1, the routing process would look like this: 1. Node B create a pointer to the mapping in question: sMapping*pMap=&NodeMapping[pMessage->uiNodeID]; 2. Node B will now convert the name: pMessage->uiNodeID=pMap->uiNodeBName; 3. And then route the message to the specified directly connected node: RouteMessage(pMessage,pMap->uiDirectlyConnectedNodeID); For this scheme to work correctly, if a node decides to change which directly connected node it will route messages to a directly connected node, it will need to update these routing tables for all directly connected nodes. If the directly connected nodes reuse internal node numbers, and the number of destination nodes that these nodes know about are less the amount of memory available for storing these node numbers. Then the node can use array lookups for sending messages. This will provide the node with O(1) message routing (see above). If the node numbers provided by the directly connection nodes exceed size of memory available for the lookup arrays (but the total node count still fits in memory), the node could shift from using an array lookup to using a hashmap lookup. More Complex Fast Routing This alternative embodiment helps ensure that O(1) routing can be used and avoids the use of a hash map. In order to ensure that nodes can always perform the fast O(1) array lookup routing, a node could provide each directly connected node with a unique node number-name mappings. This will ensure that the directly connected node won't need to resort to using a hash table to perform message routing (see above) When generating these unique number->name mappings for the directly connected node, this node would make sure to re-use all numbers possible. By reusing these numbers, it ensures that the highest number used in the mappings should never greatly exceed the maximum number of destination node updates requested by that directly connected node. For each connection the node will need to create an array of integers, where the offset corresponds to the nodes own internal node ID, and the number stored at that offset is the unique number->name mapping used to for that directly connected node. The fast routing would then look like this (see above): 1. Node B create a pointer to the mapping in question: sMapping*pMap=&NodeMapping[pMessage->uiNodeID]; 2. Node B will now convert the name: pMessage->uiNodeID=pMap->uiNodeBName; 3. And then route the message to the specified directly connected node: RouteMessage(pMessage,pMap->uiDirectlyConnectedNodeID; 4. Before sending, the name will get changed one final time pMessage->uiNodeID=UniqueNameMapping[uiConnectionID][pMessage->uiNodeID]; Where UniqueNameMapping is a two dimensional array with the first parameter being the connection ID, and the second is the number used in the unique number->name mapping for the connection with that connection ID. Reusing the numbers used in the number->name mappings for each directly connected node will require an array that is the same size as the maximum number of mappings that will be used. The array will be treated as a stack with the numbers to be reused being placed in this stack. An offset into the stack will tell this node where to place the next number to be reused and where retrieve numbers to be re-used. If the directly connected node has requested a maximum number of destination nodes that is greater then the total number of destination nodes known about by this node, then a unique mapping scheme is not needed for that directly connected node. If this circumstance changes, one can be easily generated by someone skilled in the art. When to Send User Data Packets A user data packet can be sent whenever there is a route available. Alternative embodiments could allow for QOS where certain classes of nodes had their user data packets sent first. Someone skilled in the art would be aware of variations. If no route is immediately available a payload packet could be held for some amount of time in hopes that a valid route would appear. A Time-To-Live (TTL) scheme may also be implemented by someone skilled in the art. Instead of using hops (such as a protocol like TCP/IP) the TTL might be a multiple of the fCumulativeLinkCost value for the destination node that is calculated by the node that creates the payload packets. Each node will then subtract its LinkCost for the link that the packet is received on from the TTL. If the TTL goes below zero the packet could be removed. Someone skilled in the art will recognize this as a standard TTL scheme with the use of link costs instead of hop counts (like in TCP/IP). Allowing More Important Nodes to Spread Further This alternative embodiment will allow some nodes to spread further and/or faster through network. For this embodiment to work well, most (if not all) nodes in the network will need to follow the same rules. For a class of nodes that is marked as ‘more important’, only a fraction of the link cost will be added to their fCumulativeLinkCost and/or fCumulativeLinkCostFromStream values. For example, if a node D was in the class of more important nodes, and the usual link cost for a link N was 10, then the update for node D would only have (for example) 5, or half of the link cost added to its fCumulativeLinkCost and/or fCumulativeLinkCostFromStream. How important a node is might be linked to: 1. Its magnitude (discussed earlier) 2. an arbitrary scheme based on the name of the node. 3. another value or combination of values added to or present in the node update structure. Congested or Energy Depleted Nodes This alternative embodiment can help shift network traffic away from overly congested nodes, or nodes that are running low on battery. If a node was running low on energy, or was experiencing congestion it could increase its link costs. This would help shift traffic away from this node was experiencing problems. It is helpful that the node shifts its link values slowly and waits between changes. This will help avoid unstable network oscillations. If a node experiences reduced congestion or its battery situation improves then it should slowly lower its link costs back to normal. Someone skilled in the art will be aware of the oscillation problems and be aware of schemes to deal with these problems. Nodes Sharing a Name This alternative embodiment allows nodes to share a name. In the case of a web server (for example), it can become important to provide more bandwidth and connectivity then a single server can provide. If two or more nodes were to use the same name then nodes attempting to connect to a node with that name would connect to the closest node (based on fCumulativeLinkCost). If the request was stateless (for example requesting the main page of a web site) a node could then send the request immediately, since no matter which node the request got routed to, the same result would be returned. If the node required a state-full connection, then it would initially connect to the closest node with that name. That closest node would then return its unique name that could be used to establish a connection that needed state. For example, in the sConnectionAccept struct discussed earlier the name of the node returned (sConnectionAccept.nnNameB) could be the unique name of the node. Propagation Priorities In a larger network, bandwidth throttling for control messages will need to be used. Total ‘control’ bandwidth should be limited to a percent of the maximum bandwidth available for all data. For example, we may specify 5% of maximum bandwidth for each group, with a minimum size of 4 K. In a simple 10 MB/s connection this would mean that we'd send a 4 K packet of information every: = 4096 / ( 10 ⁢ ⁢ MB ⁢ / ⁢ s * 0.05 ) ⁢ = 0.0819 ⁢ ⁢ s So in this connection we'd be able to send a control packet every 0.0819 s, or approximately 12 times every second. The percentages and sizes of blocks to send are examples, and can be changed by someone skilled in the art to better meet the requirements of their application. Bandwidth Throttled Messages These messages should be concatenated together to fit into the size of block control messages fit into. If a control message references a destination node name by its quick-reference number, and the directly connected node does not know that number, then quick reference (number->name mapping) should precede the message. There should be a split between the amount of control bandwidth allocated to route updates and the amount of control bandwidth allocated to HSPP updates. For example, 75% of the control bandwidth could be allocated to route updates and the remaining 25% could be allocated to HSPP updates. Someone skilled in the art could modify these numbers to better suit their implementation. Multiple Path Networks This section of the document describes an embodiment that allows multiple paths for end user data to form between two communicating nodes. This embodiment also allows for paths to move and shift to avoid congestion. This embodiment uses the idea of nodes and queues. Queues are used as destinations for messages (in the way that node names were used in the previous section of the document). The terminology in this section of the document may be slightly different from above, however someone skilled in the art will be able to tell which terms are equivalent. Any definitions or concepts provided in this section of the document should not be seen as invalidating or changing the meaning of definitions or concepts in the preceding part of this document. Someone skilled in the art would be aware of variations that would be possible. This network does not rely on any agent possessing global knowledge of the network. The constituents of the network are nodes and queues. This network holds to several principles: General Principles 1. The network will use simple concepts. 2. Decision-making and knowledge will be kept local, avoiding the need for global knowledge. 3. There shall be no limits on system size or topography, nodal capacity, or structural flexibility. These principles govern the design of the network. The operation of these principles is explained in detail later. Particular Principles 1. A node will only send messages to directly connected nodes that it has specified as chosen destinations. 2. A node will only send a message to a chosen destination if the latency of data in the queue on that node is greater than the latency of that chosen destination minus the minimum latency of all chosen destinations. 3. Nodes not currently in the data stream have only one chosen destination. Nodes in the data stream can have multiple chosen destinations. 4. When looking for a better chosen destination, nodes not in the data stream use passive loop checking, while nodes in the data stream use active loop checking. 5. Connections are established and maintained in a TCP/IP manner. 6. Nodes in large networks look for knowledge in the core of the network. Data Flow Principles 1. A stream of data must not cause its own path latencies to change, except in the case where the flow is past capacity. It is to be reiterated that examples are given herein in order to clarify understanding. These examples, when making specific reference to numbers, other parties' software or other specifics, are not meant to limit the generality of the method and system described herein. Nodes Each node in this network is directly connected to one or more other nodes. A node could be a computer, network adapter, switch, or any device that contains memory and an ability to process data. Each node has no knowledge of other nodes except those nodes to which it is directly connected. A connection between two nodes could be several different connections that are ‘bonded’ together. The connection could be physical (wires, etc), actual physical items (such as boxes, widgets, liquids, etc), computer buses, radio, microwave, light, quantum interactions, etc. No limitation on the form of connection is implied by the inventors. In FIG. 29 Node A is directly connected to nodes B and C. Node C is only connected to Node A. Node B is directly connected to four nodes. ‘Chosen Destinations’ are a subset of all directly connected nodes. Only ‘Chosen Destinations’ will ever be considered as possible routes for messages (discussed later). ‘Chosen Destinations’ is equivalent to ‘Best Neighbour’'s. It is used in this section of the document since ‘Best Neighbour’ may be somewhat misleading since there can only really be one ‘best neighbour’, whereas there can be multiple ‘chosen destinations’. Queues and Messages Communication by end user software (EUS) is performed using queues. Queues are used as the destination for EUS messages/payload, as well as messages that are used to establish and maintain reliable communication. Every node that is aware of the existence of a queue has a corresponding queue with an identical name. This corresponding queue is a copy of the original queue, however the contents of queues on different machines will be different. Messages are transferred between nodes using queues of the same name. A message will continue to be transferred until it reaches the original queue. The original queue is the queue that was actually created by the EUS, or the system, to be the message recipient. A node that did not create the original queue does not know which node created the original queue. Each queue created in the system is given a unique label that includes an EUS or system assigned queue number and a globally unique identifier (GUID). The GUID is important, because it guarantees that there is only every one originally created queue with the same name. For example: Format: EUSQueueNumber.GUID Example: 123456.af9491de5271abde526371 Alternative implementations could have several numbers used to identify the particular queue. For example: Format: EUSAppID.EUSQueueNumber.GUID Example: 889192.123456. af9491de5271abde526371 Each node can support multiple queues. There is no requirement that specific queues need to be associated with specific nodes. A node is not required to remember all queues it has been told about. If a node knows about a queue it will tell those nodes it is connected to about that queue. (discussed in detail later). The only node that knows the final destination for messages in a queue is that final destination node that created that queue originally. A node assumes any node it passes a message to is the final destination for that message. At no point does any node attempt to build a global network map, or have any knowledge of the network as a whole except of the nodes it is directly connected to. The only knowledge is has is that a queue exists, how long a message will take to reach the node that originally created that queue, and the maximum time a latency update from the original node will take to reach this node. Latencies Latencies play a central role in choosing the best path for data in the network. When node B tells node A that its latency is X seconds, it is saying that if node A were to pass a message to node B, that message would take X seconds to arrive at the ultimate destination and be de-queued by the EUS. This latency value as calculated by node B is: Latency=MinOverTimePeriod([Bytes In Queue])*[Bytes/Second Send Rate]+[Lowest Latency of All Chosen Message Destinations]+[Service time on this queue]+[Physical Network Latency] Min Over Time Period is a period of time determined by the time it takes to perform a minimum of five sends or receives from the send and receive nodes associated with this queue. It is also a minimum time of 30 ms (or a reasonable multiple of the granularity of the fast system timer) This will be discussed in more detail later. Bytes/Second Send Rate is the best estimate of the rate of data flowing out of the queue on this node. Lowest Latency of All Chosen Message Destinations All directly connected nodes with knowledge of this queue will provide a latency to the node that originally created the queue. This is the lowest latency of all those nodes that are chosen destinations for this queue. Service Time On This Queue is the time is takes for the node to attempt to send data from all other queues before it comes back to this one, excluding this particular queue. FIG. 30 illustrates how service time could be calculated Calculation of Service Time on a Queue For each directly connected node there is a list of queues that have that node as their chosen destination, and have data in their queue to send. In order to service queues fairly, the system will cycle through these queues sending messages from them to a ‘chosen destinations’ in a round robin fashion. Each ‘chosen destination’ will have its own list of queues that it will cycle though on its own. If quality of service (QOS) were to be implemented, this order of processing could be shifted to process the ‘more important’ queues more often. Some types of nodes will have system timers with different resolutions available. Many times the low resolution timer is much faster to read the time from, thus it makes sense to use the lower resolution timer to increase the performance of a node. The tradeoff is a slightly more complex algorithm for determining the service time on a queue. As the system cycles through the list of queues for a chosen destination, it will record the number of times it was able to send a message from a particular queue by incrementing a counter associated with that queue. It will only increment this counter if it is able to pass a message from this queue to a network adapter associated with that chosen destination. It will only pass a message from that queue if there are the appropriate queue tokens available, and it passes the latency test. Both of these concepts will be defined later. The node will also record how many messages it was able to send from all the queues. It will keep looping through this round-robin process for at least 3 or 4 ticks of the low resolution timer. In the case of Windows 2000, to take one case but not to reduce the generality of this application, this would be approximately 45 or 60 milliseconds. For increased precision of this calculation, the number of ticks should be increased. Once this time period has elapsed for a directly connected node, it will record these statistics: 1. The total number of messages sent to this directly connected node 2. The total time in seconds that this process took. Each queue will also have recorded the number of messages that were sent from that queue to that particular chosen destination during that time period. Two iterations of these statistics are stored; the one currently in progress and the last complete one. This allows the node to calculate the service time for the queue while continuing to gather new data for the next service time value. To calculate the service time for this queue with this particular chosen destination (CD) this equation is used: Service Time = ([TotalMessagesSentToCD]− [TotalMessagesSentFromQToCD])/ [TotalMessagesSentToCD] * [TotalTimeInSecondsForIterations] If there are multiple chosen destinations, we'll use this following equation to derive the service time: Service Time=1/(1/[CD1Time]+1/[CD2Time]+ . . . )) This value is only calculated when it is being sent as part of a latency calculation. This reduces computational overhead. Physical Network Latency This is defined as The time needed to send a packet similar to the average message size to a directly connected node, and have that packet be received by that directly connected node. This value is very similar to the value of ‘ping’ in a traditional TCP/IP network. This physical network latency is added to the latency provided to directly connected nodes, every time a calculation is performed using the latency that is provided by a directly connected node. For example, physical network latency would be used when: 1. Determining which is the lowest latency chosen destination 2. Detecting loops passively when not in the data stream. (defined later) 3. Picking Additional Chosen Destinations This value can be initialized by sending and timing a series of predefined packets to the directly connected node. During operation of the system this value is re-calculated based on actual performance. Assuming the network card is continuously sending data, all the system needs to do is record the amount of data sent, the average size of message and how much time elapses. The equation would look like: Physical Network Latency =[AverageMsgSize]/([TotalBytesSentDuringPeriod]/[ElapsedTime]) The time period should be chosen to be similar to the time period used to calculate service time. End User Software Unlike conventional networks where each machine has an IP address and ports that can be connected to, this system works on the concept of queues. When the end user software (EUS) creates a queue, it is similar to opening a port on a particular machine. However, there are several differences: 1. When connecting to a queue all you need is the name of the queue (For example: QueueName.GUID as discussed previously), unlike TCP/IP where the IP address of the machine and a port number is needed. The name of the queue does not necessarily bear any relationship to the node, the node's identity or its location either physically or in the network. 2. In TCP/IP when a node is connected to the network it does not announce its presence. Under this new system when a node is connected to the network it only tells its directly connected neighbors that it exists. This information is never passed on. 3. When a port is opened to receive data under TCP/IP this is not broadcast to the network. With the new system when a queue is created the entire network is informed of the existence of this queue, in distinct contrast to the treatment of nodes themselves, as described in ‘2’ immediately above. The queue information is propagated with neighbor to neighbor communication only. These characteristics allow EUS' to have connections to other EUS' without any information as to the network location of their respective nodes. In order to set up a connection between EUS' a handshake protocol similar to TCP/IP is used. 1. Node A: Creates QueueA1 and sends a message to QueueB with a request to open communication. It asks for a reply to be sent to QueueA1. The request would have a structure that looks like this: struct sConnectionRequest { // queue A1 (could be replaced with a number - // discussed later) sQNameType qnReplyQueueName; // update associated with queue A1 (explained // later) Includes Latency, UpdateLatency, etc.. sQUpdate quQueueUpdate; •} As this message travels through the network it will also bring along the definition for queue A1. This way, when this message arrives there is already a set of nodes that can move messages from the Node B to queue A1. If Node A has not seen a reply from node B in queue A1, and queue A1 on node A is not marked ‘in the data stream’ (indicating that there is an actual connection between node B and queue A1), and it still has non-infinity knowledge of queue B (indicating that queue B, and thus node B still exists and is functioning), it will resend this message. It will resend the message every 1 second, or every ‘Queue B Latency’ seconds—which ever is longer. Node B will of course ignore multiple identical requests. If any node has two identical requests on it, that node will delete all except one of these requests. 2. Node B: Sends a message to Queue A1 saying: I've created a special Queue B1 for you to send messages to. I've allocated a buffer of X bytes to re-order out-of-order messages. struct sConnectionReply { // queueB1 sQNameType qnDestQueueForMessages; // update associated with queue B1 (explained // later) Includes Latency, UpdateLatency, etc.. sQUpdate quQueueUpdate; // buffer used to re-order incoming messages integer uiMaximumOutstandingMessageBytes; } As this message travels through the network it will also bring along the definition for B1. As a result of this mechanism, when this message arrives there will be already a set of nodes that can move messages from the Node A to queue B1. If Node B does not see a reply from node A in queue B, and queue B1 on node B is not ‘in the data stream’, and node B still has non-infinity knowledge of queue A1, it will resend this message. It will resend the message every 1 second, or every ‘Queue A1 Latency’ seconds—which ever is longer. Node B will continue resending this message until it receives a sConfirmConnection message, and queue B1 is marked ‘in the data stream’. Node B will of course ignore multiple identical sConfirmConnection replies. If any node has two or more identical replies on it, that node will delete all except one. 3. Node A: whenever node receives a sConnectionReply from node B on queue A1, and it has knowledge of queue B1, it will send a reply to queue B indicating a connection is successfully set up. struct sConfirmConnection { // the queue being confirmed sQNameType qnDestQueueForMessages; } If a any node has two identical sConfirmConnection messages on it, that node will delete all except one of these messages. By attaching the queue definitions to the handshake messages the time overhead needed to establish a connection is minimized. It is minimized because the nodes do not need to wait for the queue definition to propagate through the network before being able to send. Node A can then start sending messages. It must not have more then the given buffer size of bytes in flight at a time. Node B sends acknowledgements of received messages from node A. Node B sends these acknowledgements as messages to queue A1. An example of the arrangement of nodes and queues looks like FIG. 31. Acknowledgements of sent messages can be represented as a range of messages. Acknowledgments will be coalesced together. For example the acknowledgement of message groups 10-35 and 36-50 will become acknowledgement of message group 10-50. This allows multiple acknowledgements to be represented in a single message. The structure of an acknowledgement message looks like: struct sAckMsg { integer uiFirstAckedMessageID; integer uiLastAckedMessageID; Acknowledgements (ACKs) are dealt with in a similar way to TCP/IP. If a sent message has not been acknowledged within a multiple of average the ACK time of the messages sent to the same ‘chosen destination’, then the message will be resent. The message is stored on the node where the EUS created them, until they have been acknowledged. This allows the messages to be resent if they were lost in transit. If the network informs node B that queue A1 is no long visible it will remove queue B1 from the network and de-allocate all buffers associated with the communication. If the network informs node A that queue B1 is no longer visible then node A will remove queue A1. This will only occur if all possible paths between node A and node B have been removed, or one or both of the nodes decides to terminate communication. If messages are not acknowledged in time by node B (via an acknowledgement message in queue A1) then node A will resend those messages. Node B can increase or decrease the ‘re-order’ buffer size at any time and will inform node A of the new size with a message to queue A1. It would change the size depending on the amount of data that could be allocated to an individual queue. The amount of data that could be allocated to a particular queue is dependent on: 1. How much memory the node has 2. How Many Queues it Remembers 3. How many data flows are going through it 4. How many queues originate on this node This resize message looks like this: struct sResizeReOrderBuffer { // since messages can arrive out of order, // the version number will help the sending // node determine the most recent // ‘ResizeReorderBuffer’. integer uiVersion; // the size of the buffer integer uiNewReOrderSize; There is also a buffer on the send side (node A). The size of that buffer is controlled by the system software running on that node. It will always be equal or less then the maximum window size provided by node B. Nodes in the Data Stream A node is considered in the data stream if it is on the path for data flowing between an ultimate sender and ultimate receiver. A node knows it is in the data stream because a directly connected node tells it that it is in the data stream. Data may flow through a node that is not marked as in the data stream. Only a node marked as ‘in the data stream’, is considered to be in the data stream. A node with data flowing through it but is not marked in the data stream is considered not to be in the data stream. The first node to tell another node that it is ‘in the data stream’ is the node where the EUS resides that is sending a message to that particular queue. For example, if node B wants to send a message to queue A1. Node B would be the first node to tell another node that it is ‘in the data steam’ for queue A1. A node will send a queue's like queue B without marking them ‘in the data stream’. A node in a data stream for a particular queue will tell all its nodes that are ‘chosen destinations’ for that queue, that they are in the data stream for that queue. If all the nodes that told the node that it was in the data stream tell it that it is no longer in the data stream then that node will tell all its ‘chosen destinations’ that they are no longer in the data stream. Basically, if a node is not in the data stream any more it tells all those nodes it has as chosen destinations that they are not in the data stream. This serves two purposes. First it allows the nodes in the data stream to instantly try to find better routes, Second it ensures that nodes in the data stream do not ‘forget’ about the queues. The structure used to tell another node that is in the data stream is: struct sDataStream { // the name of the queue, this could be replace with a // number that maps to the queue name. (discussed later) sQName qnName; // true if now in the stream, false if not. bool bInDataStream; }; Only data streams for queues of type B1 have the ability to created braided multi-path routes. Queues of type A1 that are in the data stream, can be limited to a single path if desired because ACK messages are both small and are easily merged together. Nodes of type B are never marked as ‘in the data stream’. A possible enhancement would be GUID probing each node about to be added to the ‘data stream’ to be sure it is non-looping. (GUID probes defined later). Node Tasks Nodes communicate with directly connected nodes to send messages created by an EUS to another EUS. Nodes will also send messages used to establish and maintain a reliable communication with another EUS. To send messages a node must determine 1. Where to Send Messages 2. When to Send Messages Each of these occasions is addressed in the following sections. Where to Send Messages To determine where it will send messages a node tries to pick a connected node: 1. That provides the best latency to the ultimate destination 2. That will not introduce a ‘loop’ 3. Not at its Sending Capacity Initial Queue Knowledge When a queue is created by an EUS the system needs a way to tell every node in the network that the queue exists, and every node needs a path through other nodes to that queue. The goal is to create both the awareness of the queue and a path without loops. When the EUS first creates the queue, the node that the queue is created on tells all directly connected nodes: 1. The Name of the Queue This is a name that is unique to this queue. Two queues independently created should never have the same name. 2. Latency Discussed previously. This is a value in seconds that describes how long it will take a message to travel from that node to the node that is the ultimate receiver. 3. ‘At Capacity’ Status Discussed Later. This is a boolean value that is true if the any of the nodes in the path of chosen destinations for this node are unable to handle more data flow then they are already have. 4. Update Latency Discussed Later. This is a value in seconds that describes the maximum time a latency update from the ultimate receiver will take to reach this node. 5. Distance from Data Stream Discussed Later. Very similar to ‘Update Latency’, except that it describes how far this node is from a node marked in the data stream. This can be used to decide which queues are ‘more important’. An alternative implementation could have it represent how far a node is from either a marked data stream, or a node carrying payload messages. This update takes the structure of: struct sQUpdate { // the name of the queue. Can be replaced with // a number (discussed later) sQName qnName; // the time it would take one message to travel // from this node to ultimate receiver and be // consumed by the EUS float fLatency; // if true, this node is already handling as // much data as it can send. (discussed later) bool bAtCapacity; // the maximum time a latency update will // take to travel from the ultimate receiver // to this node. (discussed later) float fUpdateLatency; // calculated in a similar fashion // to ‘fUpdateLatency’. and records the distance // from a marked data stream for this node. float fLatencyFromStream’; }; Regardless of whether this is a previously unknown queue, or an update to an already known queue the same information can be sent. Delayed sending of node updates and the ordering of node updates should follow the same approach described previously. If this is the first time a directly connected node has heard about that queue it will choose the node that first told it as its ‘chosen destination’ for messages to that queue. A node will only send EUS messages/payload to a node or nodes that are ‘chosen destinations’, even if other nodes tell it that they too provide a route to the EUS created queue. If a node picks a directly connected node as a ‘chosen destination’, it must tell that node that it was selected as a ‘chosen destination’. The structure of the message looks like this: struct sPickedAsChosenDestination { // the name of the queue. Could be replaced with a number // (discussed later) sQName qnName; // true if the node this message is being sent to is a // a chosen destination for this queue. bool bSelected; }; A node will never pick another node as a ‘chosen destination’ if that node already has this node as a ‘chosen destination’ for that queue. If this happens because both nodes pick each other at the same time it needs be resolved instantly. One approach would be for both nodes to remove each other as chosen destinations, wait a random amount of time and then try to re-select each other. In this fashion a network is created in which every node is aware of the EUS created queue and has a non-looping route to the EUS queue through a series of directly connected nodes. FIG. 32 is a series of steps showing knowledge of a queue propagating the network. The linkages between nodes and the number of nodes in this diagram are exemplar only, whereas in fact there could be indefinite variations of linkages within any network topography, both from any node, between any number of nodes. At no point does any node in the network attempt to gather global knowledge of network topology or routes. The system provides every node with the names of the EUS created queues and the latencies the directly connected nodes provide to the EUS created queues. Even if a node has multiple possible paths for messages it will only send messages along the node or nodes that it has chosen as its ‘chosen destinations’. When a node has selected another directly connected node as its ‘chosen destination’, it will tell that node of its choice in order to avoid loops that may be created if two nodes pick each other as ‘chosen destinations’. Every node keeps track of what queue's it has told its directly connected nodes about. Every new queue that the directly connected node has not been told about will be immediately sent (see Propagation Priorities). In the case of a brand new connection, nodes on either side of that connection would send knowledge of every queue they were aware of. If a node does not contain enough memory to store the names, latencies, etc of every queue in the network the node can ‘forget’ those queues it deems as un-important. The node will choose to forget those queues where this node is furthest from a marked data stream. The node will use the value ‘fLatencyFromStream’ to decide how far this node is from the marked data stream. An alternative embodiment could use the value fLatencyFromStream’ to represent its distance from either a marked data stream, or a node carrying payload packets. The only side effect of this would be an inability to connect to those queues, and for those nodes that rely exclusively on you for a destination to connect to those queues. The value ‘fLatencyFromStream’ can be used to help determine which queues are more important (See Propagation Priorities). If the node is 100 seconds from the marked data stream for queue A, and 1 second away from a marked data stream for queue B, it should chose to remember queue B—because this node is closest to a marked data stream and can be more use in helping to find alternative paths. A node that is told about a new queue name with latency of infinity (discussed later) will ignore that queue name. Queue Name Optimization and Messages Every queue update needs to have a way to identify which queue it references. Queue names can easily be long, and inefficient to send. Nodes can become more efficient by using numbers to represent long names. For example, if node A wants to tell node B about a queue named ‘THISISALONGQUEUENAME.GUID’, it could first tell node B that: 1=‘THISISALONGQUEUENAME.GUID’ A structure for this could look like: struct sCreateQNameMapping { int nNameSize; char cQueueName[Size]; int nMappedNumber; }; Then instead of sending the long queue name each time it wants to send a queue update, it could send a number that represented that queue name. When node A decides it no longer wants to tell node B about the queue called ‘THISISALONGQUEUENAME.GUID’, it could tell A to forget about the mapping. That structure would look like: struct sRemoveQNameMapping { int nNameSize; char cQueueName[Size]; int nMappedNumber; }; Each node would maintain its own internal mapping of what names mapped to which numbers. It would also keep a translation table so that it could convert a name from a directly connected node to its own naming scheme. For example, a node A might use: 1=‘THISISALONGQUEUENAME.GUID’ And node B would use: 632=‘THISISALONGQUEUENAME.GUID’ Thus node B, would have a mapping that would allow it to convert node A's numbering scheme to a numbering scheme that, makes sense for node B. In this example it would be: Node A Node B 1 632 . . . . . . . . . . . . Using this numbering scheme also allowueA1 andes to be messagetagged aeB with ch queuet to opee destined for. For example, if the system had a message of 100 bytes, it would reserve the first four bytes to store the queue name the message belongs to, followed by the message. This would make the total message size 104 bytes. An example of this structure also includes the size of the message: struct sMessage { int uiQueueID; int uiMsgSize; char cMsg[uiMsgSize]; } When this message is received by the destination node, that node would refer to its translation table to decide which queue this message should be placed in. Path to Queue Removed If a node that is on the path to the node where the original queue was created, is disconnected from the node that it was using as its only ‘chosen destination’, that node will first attempt to find a non-looping alternative path. It will do this by examining all nodes that are not currently sending to this node (ie. Have this node as a ‘chosen destination’). If it picked a node that has this node as a ‘chosen destination’ a loop would be created. This node will use a GUID probe to check for loops in the remaining possible nodes using the ‘GUID probe’ process described later in ‘Adding additional routes’. If all potential alternative paths are loops, the node will set its latency to infinity, and tell all connected nodes immediately of this new latency. If a node has a ‘chosen destination’ tell it a latency of infinity, it will instantly stop sending data to that node and will remove that node as a ‘chosen destination’. If all ‘chosen destinations’ have been removed the node will set its own latency to infinity and immediately tell its directly connected nodes. Once a node has set its latency for a queue to infinity and tells its directly connected nodes, it waits for a certain time period (one second for example). At the end of this time period the node will instantly choose as a chosen destination any directly connected node that does not have a latency of infinity, and resume the sending of data. If it does not see a suitable new source within double the original fixed time period (2 seconds for example) after the first time period has elapsed, it will delete messages from that queue, and remove knowledge of that queue. This time period is based on a multiple of how long it would take this node to send the update that this queue has gone to infinity. (See Propagation priorities later). This value is then multiplied by 10, or a suitably large number that is dependant on the interconnectedness of the network. For example, if the network is very large and sparsely connected, the number would be higher then 10. In a dense, well connected network, the value would be 10. If a node's latency moves from infinity to non-infinity it will immediately tell all directly connected nodes of its new latency. In this example, in a network with ten nodes, an EUS has created a queue on one of the nodes that has a direct connection to two nodes, one on each side of the network. In FIG. 33, every node in the network has just become aware of the EUS created queue (which has zero latency—lower right), the numbers in each node represent the latency in seconds as defined above. Next, in FIG. 34, one of the connections between the node with the EUS created queue is removed The directly connected node that lost its connection to the node with the EUS created queue will check to see if any of the nodes it is directly connected to are using it as sender. Since all of them are, it does not need to probe them with GUIDs to determine if they loop. This node then sets itself to a latency of infinity. This is shown in FIG. 35. It immediately tells all directly connected nodes of its new latency. If all the node's ‘chosen destinations’ are at infinity, those nodes' latencies become infinity as well. This is shown in FIG. 36. This process continues until all nodes that can be set to infinity are set to infinity. This is shown in FIG. 37. At this point, every node that has been set to infinity pauses for a fixed amount of time (for example, one second), and then picks the lowest latency destination it sees that is not infinity. This is shown in FIG. 38. As soon as a node that was at infinity becomes non-infinity it will tell the nodes directly connected to it immediately. If one of those nodes is at infinity it will select the first connected node to provide it with a non-infinity latency as its chosen destination. This is shown in FIG. 39. At this point the network connections have been re-oriented to enable transfer of all the messages destined for the EUS created queue to that queue. If a node's latency for a queue is at infinity for more then several seconds the node can assume that there is no other alternative route to the ultimate receiver and any messages in the queue can be deleted along with knowledge of the queue. FIG. 40 outlines the above processes. Converging on Optimal Paths for Nodes ‘Not In The Data Stream’ Nodes are always trying to lower their latency to the originally created queue by selecting different chosen destinations. Only the queue that is established on nodes between the ultimate sender and ultimate receiver for transferring EUS message data will use braided multiple paths for increased bandwidth. The ultimate sender marks this path by telling all ‘chosen destinations’ that they are in this data sending path (‘in the data stream’). Each of those ‘chosen destination’ nodes tell their own ‘chosen destination’ nodes that they to are ‘in the data stream’. FIG. 42 illustrates this. If all senders to a particular node are disconnected or tell that node that it is no longer in the ‘data stream’, or the node that told it that it was in the ‘data stream’ tells it that it is no longer a ‘chosen destination’, then it will clear the ‘in the data stream’ flag and tell all its chosen destinations they are no longer in the data stream. If a node is currently in the path of EUS message transfers between two node with EUS it uses a different mechanism to select a new ‘chosen destination’. If a node that has multiple chosen destinations is removed from the data stream it will remove all chosen destinations except that one with the lowest latency. This enables the mechanism for finding loops to remain effective since that mechanism will only work with one chosen destination. A node that is not currently in the data stream will always try to improve its latency to the ultimate receiver by selecting a node with a lower latency then its current chosen destination. A node needs to be sure that when it is selecting a different ‘chosen destination’ that it will not introduce a loop. A node looking to upgrade its connection will prefer any node that is not ‘at capacity’ (explained later) over any node that is ‘at capacity’, regardless of latency. A the node is not currently in the path of EUS messages/payload it is not allowed to use GUIDs, or messages to check to see if the possible new chosen destination is a loop because a network of any size would quickly be overrun with these messages. Instead it watches the latency of a potential choice by waiting for a periodic, automatic latency update from that node and compares it with the latency of its currently ‘chosen destination’. In the circumstance where a potential new destination would create a loop, if chosen, the major cause of apparent lower latency is lag introduced by the travel time for data in the loop between the current node and this potential new node. For example, if every second the current node's latency increases by 1 s, and there was a loop with a three second lag between this node and the new potential ‘chosen destination’, the new potential ‘chosen destination’ would always appear to have 3 second lower latency then the current chosen destination. FIG. 43 is another example of a potential loop to be avoided If the current node chose this apparently ‘better choice’ it would create a loop in the system. This is where the ‘fUpdateLatency’ value from the queue update is used. This number is the maximum time it takes for a latency update to travel from the node that created the queue. The actual calculation of this value is discussed later. In the previous diagram node B is trying to decide if node F is a better choice then node A. It will compare the difference in ‘fUpdateLatency’ from node F and node A. The two values in this example would be: Node A fUpdateLatency: 8 s Node F fUpdateLatency: 13 s Since node A is the currently chosen destination, and node F's ‘fUpdateLatency’ is higher then node A's ‘fUpdateLatency’ node B needs to check to see if node F is actually routing its messages through as series of nodes to node B. Node B can't immediately discard node F as a valid new ‘chosen destination’ just because it has a higher ‘fUpdateLatency’. This is because the alternative route that node F provides, although potentially a longer path to the ultimate destination it could be faster because of congestion on the route provided by node A. The basic idea behind passive loop testing is the following. The fUpdateLatency difference between A and F (in this example 5 seconds) is how long it will take at maximum for a latency update sent from node B to reach node F. If a loop is present, then the maximum latency value from node F during this period of time will be greater then the median latency value from node A during the same time period before this time. The total time period for the median must never be longer then value of node A's ‘fUpdateLatency’. For example, if the difference between the ‘fUpdateLatency’ values of node A and node F was 500 seconds, and node A's ‘fUpdateLatency’ was 8 seconds, the time period for calculating the median would be only 8 seconds. The time period watching for a maximum would be 500 seconds. FIG. 44 illustrates this. This technique may yield a false positive for a loop, however it will only very rarely yield a false negative. Dealing with a loop is discussed later. Using a median in the above case would be ideal, however calculating a median requires storing all the observations. Below is a pseudo code algorithm that can approximate a median and requires a low fixed overhead. float fPart1 = 0; float fPart2 = 0; int nCount = 0; while (not done all observations) { float fCurOb = GET_CURRENT_OBSERVATION( ) fPart1 = fPart1 + fCurOb; nCount = nCount + 1; fPart2 = fPart2 + abs( fPart1 / nCount − fCurOb); } float fCloseToMedian = fPart1 / nCount1 − fPart2/nCount; If the observations' time periods are too small they will get rounded up one iteration of the low resolution timer. During the observation period for both the median and the maximum, the values of fUpdateLatency may change. If the difference between the two ‘fUpdateLatency’'s increases, the new increased time period will be used. Lower values will be ignored. This can lead to the circumstance where the ‘median’ time period will be smaller then the ‘maximum’ time period. This is fine. If the ‘fUpdateLatency’ for node F is less then node A, or becomes less during the course of the comparison, then no loop is possible and the node can select node F as a new chosen destination without further delay. If the queue on this node is ‘at capacity’, we'll prefer to pick a node with a higher latency that is not ‘at capacity’. This node will still wait the appropriate time to be sure that this ‘not at capacity’ node stays ‘not at capacity’. If the considered node turns to ‘at capacity’ during the time period, but it provides a lower latency and not a loop then this node can use that node as a ‘chosen destination’. If this node is currently at infinity, this process will not be used. (See previous) If during the ‘maximum’ time period a latency update arrives from node F greater then the median of node A, then the test will end indicating a loop. Node B will not wait for the entire ‘maximum’ time period to expire. The exception to this is if this node is ‘at capacity’ and the node being considered is not ‘at capacity’. Since a node not in the data stream can have only one chosen destination for that queue, when it picks a new chosen destination it will stop using the old chosen destination. When a node not in the data stream switches to new chosen destination it will record the difference between current chosen destination's ‘fUpdateLatency’ and the new chosen destination's ‘fUpdateLatency’. This value will be stored and used to help detect a loop. (discussed later) At Capacity Checking Each queue of each node also has a mechanism to detect when it is sending or receiving data at capacity. A queue on a node is considered at capacity when the latency of data in its queue exceeds max([all chosen destination latencies])−min([all chosen destination latencies]) for more then 5 time intervals, for example. A time interval is defined as the time every destination able to send has sent a certain number of messages (for instance, 10), or a minimum of a certain time period (for example, double the minimum granulation of the fast system timer), or a maximum of another time period (for example 6 seconds). It is important that enough time has elapsed during the time interval that the chosen destinations have had the chance to bring the total amount of data in the queue to the lowest point possible. For example, if data is flowing in at 100 bytes every second, and flowing out at 500 bytes every five seconds, an absolute minimum time interval of 5 seconds would be required. FIG. 45 is an example of queue levels and minimums during a time interval. A node is considered at capacity if it is unable to bring the queue latency down to this level over this time period. If it is unable to do so, then there is too much data flowing into the node to successfully send it out almost as soon as it arrives. When a node is at capacity it tells all nodes that are connected to it. If all ‘chosen destinations’ for a queue on a node are marked ‘at capacity’ then that node tells all its directly connected nodes it that it is also at capacity. ‘At capacity’ updates travel through the network at the same time as normal latency updates. They do not preempt normal data flow. (see sQueueUpdate previously) As discussed previously, nodes that are not in the flow of data will attempt to find non-looping alternatives to ‘chosen destinations’ that become marked ‘at capacity’. If a node is in the data stream, it will not attempt to remove an ‘at capacity’ node as a ‘chosen destination’ because of its ‘at capacity’ status, it will make its decision to remove that node based on latency only. Finding Additional Routes when at Capacity A node ‘at capacity’ because it has too much data flowing into it will make a list of all possible additional routes using directly connected nodes. A possible additional route is a node that: 1. Is not at capacity 2. Is not sending to this node 3. Will not Create a Loop 4. Has a destination of a queue other than the node querying (ie. Not loop creating) For each of these possible routes the at-capacity node will create a unique GUID. This GUID will be sent down each possible route to test each of the routes for a loop. If a loop is detected that route is discarded from the list of possible additional routes. Each GUID that corresponds to a possible route is sent to the destination node next along that route. That node will store and forward that GUID on to all nodes it has as ‘chosen destinations’. If the node chooses a new node for a destination then the GUID will be passed to that new node. A node will deactivate a GUID by telling all ‘chosen destinations’ to forget the GUID. If all the nodes telling it to remember the GUID, tell it to stop remembering the GUID, or tell them that they are no longer chosen as a destination, or they are disconnected, the GUID is deactivated. FIG. 46 is an example of this. In FIG. 46 if the node at capacity sees a GUID it sent to a possible additional chosen destination it knows that choice would be a bad choice. In this same manner the GUID sent to a chosen route will enumerate all paths along which data could flow from that node. If the machine that is at capacity sees one of the GUID's it has sent out coming back to it from a node that is sending it data then it knows that the node down which it sent the GUID forms part of a loop, and that possible route is eliminated as a choice to relieve the ‘at capacity’ status. A GUID message is composed of a GUID, the name of the queue in question, a ‘travel time’, and a note telling the node to either ‘remember’ or ‘forget’ this GUID. When a node is told of a GUID to remember or forget it will send this message as soon as possible (see Propagation Priorities). If it has already seen and processed this GUID message it will ignore it. A GUID message will take the structure of: struct sGUIDProbe { // could also be a number that represents this queue // (discussed previously) sQueueName qnQueueName; // true if the node is supposed to remember this GUID // false if its supposed to forget it. bool bRememberGUID; // the actual GUID char cGUID[constant_Guid_Size]; // how far the GUID will travel (based on fUpdateLatency) float fMaximumGUIDTravelTime; }; The travel time for the GUID is set as triple (for example) the difference between the fLatencyUpdate of node looking for a new route and the fLatencyUpdate of the possible new route that is not at capacity. Each time a node receives a GUID probe it subtracts its contribution to the fLatencyUpdate value from the fMaximumGUIDTravelTime time before it tells its directly connected nodes of this GUID probe (instead of adding this value to fLatencyUpdate they way it normally does). If after it subtracts its contribution from fMaximumGUIDTravelTime the value is less then 0, the GUID probe is not passed on to any chosen destinations. The value that it subtracts is based on the time for a round robin update of all the queues in the same class as the queue this GUID probe is based on. (discussed later, see ‘Propagation priorities’—‘second group’) The node that is at capacity will wait for a minimum of its initial ‘fMaximumGUIDTravelTime’ to give the GUIDs a chance to work through the network and loop back to the ‘at capacity’ node, if a loop exists. If the time has elapsed, all potential choices whose GUID did not make it back to the node are considered valid options. The lowest latency, not ‘at capacity’, non-looping node is chosen and a message is sent to that node indicating that it is now a ‘chosen destination’. This is done to prevent two directly connected nodes from choosing themselves as destinations, creating a loop. If two directly connected nodes select each other as destinations at the same time, they will both instantly switch back to their previous destinations and retry the process of finding additional destinations. Since the GUID mechanism includes a random interval the likelihood of the two nodes again selecting each declines dramatically at each iteration. If all possible routes came back as loops, the ‘at capacity’ node will remove the GUID's. If this node is still ‘at capacity’ after a period of time it retry the process looking for alternatives. It will wait (for example) three times the maximum ‘fMaximumGUIDTravelTime’ used for the last round of GUID probes. Even though a node has several choices where to send data, the maximum latency allowed in the queue is still max([all chosen destination latencies])—min([all chosen destination latencies]) subject to available memory on that node. As soon as this new destination is chosen the node will be able to clear its ‘at capacity’ status. This maximum is not a hard limit, since it is possible there may be outstanding flow control quota allowing for a bit more data to be sent. (see flow control) Every time a token update is sent to a node sending data to this node, the current minimum latency over the last time interval as well as the ‘at capacity’ flag is sent along as well. This enables sending nodes to have the current latency data enabling them to always choose the best route. Removing Unused Additional Routes Because nodes not in the data stream only ever have one chosen destination, they don't remove additional sources, instead they switch from one source to a better source. (discussed previously). Nodes in the data stream are the only nodes that are given the potential to develop multiple data paths. (discussed previously). If a node in the data stream does not use a particular ‘chosen destination’ to send data for a certain amount of time, then the node will remove that chosen destination from its list of chosen destinations and alert that node that it is no longer a chosen destination. Telling a node that is no longer a chosen destination will also remove the ‘in the data stream’ flag unless another node that is ‘in the data stream’ has also selected this node as a chosen destination. The certain amount of time to wait before removing an un-used chosen destination should be relatively long compared to the amount of time required to create the connection in the first place. The amount of time a chosen destination is maintained could also be dynamically adjusted over time based on how much time elapsed between when a node is removed until when it is re-added in. Deciding when to Add/Remove a Chosen Destination while not ‘At Capacity’ A node must always have at least one ‘chosen destination’ if any possible choice exists. (if not its latency would be at infinity) If a node is in the data stream for a particular queue it may have more then one ‘chosen destination’ if the queue is the queue used to transfer data. In our TCP/IP handshake example, this would be queue B1 (diagram previously). If a node is not at capacity, and is not able to remove a ‘chosen destination’ because all of the ‘chosen destinations’ are too active to be removed (see previous) then it will try to add a new chosen destination with a latency that is less then highest latency of all the ‘chosen destinations’. It must only choose possible ‘chosen destinations’ that are not ‘at capacity’. The node does this in hope that it will replace its current ‘chosen destinations’ with better choices. This will allow the node to make the entire route faster, as well as need less buffer space for messages passing through it. The node will probe the possible choice with a GUID probe (described above). If the GUID probe fails (a loop was detected) then next time the node attempts to optimize this connection it will pick another directly connected node with the next lowest latency. FIG. 47 is a flowchart that illustrates this process. Resolving Accidentally Created Loops If a loop is accidentally created in nodes that are not part of the marked data stream their latency and ‘fUpdateLatency’ will spiral upwards. FIG. 48 shows a loop that was accidentally created in nodes not in the data stream. Loops in nodes not in the data stream will be rare because of the way we compare latencies for possible new chosen destinations. (see above). Because we probe possible new destinations explicitly for loops using GUIDs, loops will not be created in the data stream except very, very rarely as a result of intervening path changes after the GUID mechanism has been used. Simple loops that do not involve nodes ‘at capacity’ or nodes that have gone to infinity will be easily resolved using the standard ‘passive’ loop find mechanism. Nodes in a loop will create the appearance of knowing about the queue with no actual connection to the ultimate receiver for that queue. For example, if a loop is maintained, and the actual ultimate receiver leaves the network, this loop would continue to self-maintain this queue knowledge. This problem occurs when: 1. Nodes inside the loop are not ‘at capacity’ and nodes outside the loop are ‘at capacity’. 2. Nodes outside the loop are at ‘infinity’. In both cases the solution is to detect that there is a possibility of a loop and change their latency to infinity in the same manner as discussed previously. This will cause the nodes to move into a non-loop state quickly. If we're on a node that is not in the data stream, and there are directly connected nodes that are: 1. ‘At Capacity’ when this node is not 2. Have a latency of infinity when we do not Then loop testing will be invoked. During the process of choosing a new ‘chosen destination’ the node recorded the difference in the ‘fUpdateLatency’'s of the new ‘chosen destination’ and the old ‘chosen destination’. This time in seconds multiplied by three will be referred to as the ‘possible loop time’ (PLT). Our loop testing will begin by recording the minimum ‘fUpdateLatency’, ‘fLatencyFromStream’ and ‘flatency’ for the PLT. If during two successive iterations, all three recorded values (‘fUpdateLatency’, ‘fLatencyFromStream’ and ‘fLatency’) were less then the iteration before, then a GUID probe is used to determine if there is in fact a loop. The GUID probe (see previously) is set up to travel PLT*5 (for example) time through the network. If a loop is detected then the node that detected it will go to infinity in the same manner as ‘Path to Queue Removed’. If the GUID probe fails then the node returns to its loop testing described above. If this process repeats three times then the node will goto ‘infinity’ anyway. (See ‘Path to Queue Removed’) When to Send Messages In determining when to send a message the node decides if the node being sent to: 1. Has room to store the message 2. Provides latency to the destination that is useful given the latencies of other directly connected nodes and the amount of data in this node's queue. Send to Useful Chosen Destinations Only Even if a node has chosen multiple ‘chosen destinations’ for sending messages it does not mean that they will all be used. A ‘chosen destination’ will only be used if the current latency of data in the queue is equal or greater then the =[Chosen Destination Latency]−min([All Chosen destinations]) If a ‘chosen destination’ latency is x seconds over the minimum of all the ‘chosen destinations’ latencies then x seconds of data would be stored on that node before using that chosen destination. If a chosen destination has latency above the current queue latency (as defined previously) then we have the option of sending a message to that node asking it to inform us when the latency of that node drops below a specified value. Asking a node to send an update at a specified value will also cause the node to send the current latency. This solves the problem of rapid updates required to keep the sender informed as to the latency of the receiver. Latency and ‘at capacity’ updates are passed both in token updates (defined later), as well as a constant stream that is throttled not to exceed X % of node to node bandwidth. Usually this number would be 1-5%. The node would cycle through all known available latencies in a round-robin fashion. (See Propagation Priorities) Other ways to determine what order or frequency to send queue updates could also be used: 1. Percentage Change 2. A particular class of queue names are marked for more frequent updating 3. A ‘distance from data stream’ counter could be used to increase latency updates in the vicinity of the data stream. If no queue messages are sent to a chosen destination for a certain time period then that chosen destination is removed from the list of chosen destinations for that node. This time period would be at least an order of magnitude greater then the total time needed to establish the destination initially. An adaptive approach could also be used (described previously). Flow Control Each node has a variable amount of memory, primarily RAM, used to support information relevant to connections to other nodes and queues, e.g. message data, latencies, GUIDs, chosen destinations etc. An example of the need for flow control is if node A has chosen node B as a destination for messages. It is important that node A is not allowed to overrun node B with too much data. Flow control operates using the mechanism of tokens. Node B will give node A a certain number of tokens corresponding to the number of bytes that node A can send to node B. Node A is not allowed to transfer more bytes then this number. When node B has more space available and it realizes node A is getting low on tokens, node B can send node A more tokens. There are two levels of flow control. The first is node-to-node flow control and the second is queue-to-queue flow control. Node-to-node flow control is used to constrain the total number of bytes of any data (queues and system messages) sent from node A to node B. Queue-to-queue flow control is used to constrain the number of bytes that move from a queue in node A to a queue in node B with the same name. For example, if 10 bytes of queue message move from node A to node B, it costs ten tokens in the node-to-node flow control as well as 10 tokens in the queue-to-queue flow control for that particular queue. When node B first gives node A tokens, it limits the total number of outstanding tokens to a small number as a start-up state from which to adjust to maximize throughput from node A. Node B knows it has not given node A a high enough ‘outstanding tokens’ limit when two conditions are met: if node A has told node B that is had more messages to send but could not because it ran out of tokens, and Node B has encountered a ‘no data to send’ condition where a destination would have accepted data if node B had had it to send. If node A has asked for a higher ‘outstanding tokens’ limit and node B has not reached ‘no data to send’ condition, node B will wait for a ‘no data to send’ condition before increasing the ‘outstanding tokens’ limit for node A. Node B will always attempt to keep node A in tokens no matter the ‘outstanding tokens limit’. Node B keeps track of how many tokens it thinks node A has by subtracting the sizes of messages it sees from the number of tokens it has given node A. If it sees node A is below 50% of the ‘outstanding limit’ that node B assigned node A, and node B is able to accept more data, then node B will send more tokens up to node A. Node B can give node A tokens at its discretion up to the 50% point, but at that point it must act. Assigning more tokens represents an informed estimate on Node B's part as to the maximum number of tokens node A has available to send data with. This number of tokens, when added to node B's informed estimate of the number of tokens node A has, will not exceed the ‘outstanding tokens’ limit. It may also be less, depending on the amount of data in node B's queue. (discussed later). For example, lets consider node A and node B that are negotiating so that node A can send to node B. FIG. 49 shows the current state. Node B has created the default quota it wants to provide to node A. It then sends a message to node A with the quota (the difference between the current and the maximum). It also includes a version number that is incremented each time the maximum limit is changed. The message node B sends to node A looks like this: struct sQuotaUpdate { // the version unsigned integer uiVersion; // the queue name or number (see previous) sQNName qnName; // how much additional quota is sent over unsigned integer uiAdditionalQuota; }; We do this so that when node A tells us that it wants to send more data, it will only do so once for each time we adjust the maximum limit. FIG. 50 shows the current state. If node A wants to send a message of 5 bytes to node B it will not have enough quota. Node A would then send a message to node B saying ‘I'd like to send more’. It will then set its ‘Last Want More Ver’ to match the current version. This will prevent node A from asking over and over again for more quota if node B has not satisfied the original request. This message looks like this: struct sRequestMoreQuota { // the queue name or number (see previous) sQNName qnName; }; FIG. 51 shows this state. Node B has no data in its queue and yet it would have been able to send to its chosen destination, so it will increase the maximum quota limit for node A to 100 bytes. It will send along the new quota along with the new version number. FIG. 52 shows this state. Node A now has enough quota to send its 5 byte message. When the message is sent, node A removes 5 bytes from its available quota. When the message is received by node B, it removes 5 bytes from the current quota it thinks node A has. FIG. 53 shows this state. Messages can continue to flow until node A runs out of quota or messages to send. If the quota that node B thinks node A has drops below 50 bytes, node B will send a quota update immediately. A quota update that does not change the maximum limit will not result in the version being incremented. Quota updates for different queues can piggy back together, thus if one quota update ‘needs’ to be sent, others that just need a top off can be sent at the same time. This will reduce the incidence of a special message being sent with just one quota update. In general, system messages can also be piggy-backed with data messages to reduce their impact. The same approach to expanding the ‘outstanding limit’ for queue-to-queue flow control also applies to node-to-node flow control. The ‘outstanding limit’ is also constantly shrunk at a small but fixed rate by the system (for example, 1% every second). This allows automatic correction over time for ‘outstanding limits’ that may have grown large in a high capacity environment but are now in a low capacity environment and the ‘outstanding limit’ is unnecessarily high. If this constant shrinking drops the ‘outstanding limit’ too low, then the previous mechanism (requesting more tokens and more being given if the receiving node encounters a ‘no data to send’ condition) will detect it and increase it again. At Capacity Flow Control When giving other nodes quota to send, it is important that they be given enough quota to move the receiving node to an ‘at capacity’ state and keep it there if possible. If the latency in a queue on the node is over (max([latency all chosen destinations])−min([latency all chosen destinations])), then each incoming flow of data must not get more than their maximum ‘outstanding limit’ of quota amount over this maximum latency. This is implemented by having an ‘over capacity token count’ variable attached to the flow control structures on the receiving side that records the number of bytes received from that source while the queue is over capacity. This number is subtracted from the ‘max outstanding limit’ when it comes to providing the sending node with more quota. If the queue latency drops below its maximum latency the ‘over capacity token count’ variable is set to 0. When data is removed from a queue that is above capacity, we take the number of bytes that have been removed and subtract that sum of bytes as evenly as we can from all ‘over capacity token count’ variables that are greater then zero. It is important that the ‘over capacity token count’ is always equal to or greater then zero. For example, if 120 bytes are removed from the queue and there are four connections putting data into that queue and their ‘over capacity token counts’ are 0, 100, 20, 50, we would divide the number of bytes (120) by the number of ‘over capacity token count’ variables greater then zero (three), this gives us 40. Since the lowest ‘over capacity token count’ variable is less then 40 (20), we will subtract that number (20) from all ‘over capacity token count’ variables. This leaves us with 0, 80, 0, 50 and have 60 bytes still left. We repeat the process and subtract 30 from each of the remaining two ‘over capacity token count’ variables, leaving us 0, 50, 0, 20. Flow Control for EUS Queues In TCP/IP window size selection is important. If the window size in TCP/IP is too small performance will suffer, if it is too large system resources will be used up without increasing performance. This invention allows rapid convergence to the best window size using a ‘send-side only’ algorithm. Nodes that are part of the marked data stream will only buffer enough data to ensure they can send at maximum speed. This means that even if there are gigabytes of data to send, only a relatively fixed, small percent will ever be in transit at a given time. However, if there are gigabytes of data to send (instead of just one small message), many more paths will be used to transfer that data. However, no matter how many paths were used the total amount of data in transit would not exceed the buffer provided to the ultimate sender by the ultimate receiver. A key metric that a node uses to determine which nodes they will send to is latency. If there are a thousand seconds of data remaining to send, then all paths with a latency to the destination of under 1000 seconds should be considered. If there is a very small amount of data and the latency to send it is 10 ms, then very few paths (and only the fastest) will be used to transfer data. This allows nodes to recruit as many or as few nodes as needed to insure the fastest transfer of data. This technique allows us to implicitly increase bandwidth when needed by trading off latency that is not needed. The amount of data in transit is also limited by the size of buffer the sending node can allocate to that queue. The best size for the send buffer is such that its latency is: SendBufferLatency=>Max(AllChosenDestinationLatencys)−Min(AllChosenDestinationLatencys) This means that if we can keep adding nodes to our chosen destination list, we'll be able to keep expanding our send buffer on the ultimate sender. The node with the EUS sending the messages should allow this send buffer to grow to a point where the EUS can keep the queue ‘at capacity’ (in the same way as flow control works). This ensures that all ‘chosen destinations’ can be used as much as possible. At the ultimate receiver messages received are placed into the re-order buffer. As the node is able to place these messages in order, they are shifted into a queue that the EUS uses to de-queue messages for processing. The size of this de-queue buffer is set the same way as the queue buffers between nodes (discussed in flow control). If the queue the EUS uses to retrieve messages exceeds its maximum size, this node tells its directly connected nodes that it is ‘at capacity’, and does not give any more quota to the directly connected nodes. Ordered messages from the re-order buffer are still placed into this queue used by the EUS, however the flow of incoming messages to the re-order buffer will be cut off because this node is no longer handing out quota to directly connected nodes for this queue. If the queue the EUS uses gets completely empty, and directly connected nodes wanted to send more messages to the node with the EUS, then the maximum size of the queue that the EUS uses is expanded (in the same way the flow control works). The size of this queue is also subject to downward pressure that same way the queues are during flow control. The size of the re-order buffer has no relation to the number of messages (or the number of bytes) that the queue used by the EUS can hold. If the receiving EUS were to completely stop processing messages, all the nodes in the network would shift to ‘at capacity’ for the queue, and the ultimate sender would very quickly be given no more quota with which to push messages into the network. Propagation Priorities In a larger network, bandwidth throttling for control messages will need to be used. We're going to use several types of throttling. Total ‘control’ bandwidth will be limited to a percent of the maximum bandwidth available for all data. Control messages will be broken into to groups. Both these groups will be individually bandwidth throttled based on a percentage of maximum bandwidth. Each directly connected node will have its own version of these two groups. For example, we may specify 5% of maximum bandwidth for each group, with a minimum size of 4 K. In a simple 10 MB/s connection this would mean that we'd send a 4 K packet of information every: = 4096 / ( 10 ⁢ ⁢ MB ⁢ / ⁢ s * 0.05 ) ⁢ = 0.0819 ⁢ ⁢ s So in this connection we'd be able to send a control packet every 0.0819 s, or approximately 12 times every second for each group. The percentages, and sizes of blocks to send are examples, and can be changed by someone skilled in the art to better meet the requirements of their application. First Bandwidth Throttled Group The first bandwidth throttled group sends these messages. These messages should be concatenated together to fit into the size of block control messages fit into. 1. Name to number mappings for queues needed for the following messages. 2. Standard Flow Control Messages 3. GUID probes 4. Informing a node if its now a ‘Chosen Destination’ 5. HSPP messages 6. Initial Queue Knowledge/To Infinity/From Infinity of HSPP queues 7. Initial Queue Knowledge/To Infinity/From Infinity of non-HSPP queues. Second Bandwidth Throttled Group The second group sends latency updates for queues. It divides the queues into three groups, and sends each of these groups in a round robin fashion interleaved with each other 1:1:1. The first two groups are created by ordering all queues using the value of ‘fLatencyFromStream’. If the queue has multiple chosen destinations, then the ‘chosen destination’ with the lowest latency is used to decide which ‘fLatencyFromStream’ value we're going to use. The queues are ordered in ascending order in a similar manner described previously in the single path embodiment. They are divided into two based on how many updates can be sent in a half a second using the throttled bandwidth. This ensures that the first group will be entirely updated frequently, and the rest will still be updated—but less frequently. The third group is composed of queues where this node is in the data stream. Each latency update includes a value ‘fUpdateLatency’. This value ‘fUpdateLatency’ is calculated separately for queues in each of the three groups. It is calculated as the amount of time that it takes to send all items in the group once. This value is added to the ‘fUpdateLatency’ of the chosen destination with the lowest ‘fLatency’. This value is also used when determining how far a GUID probe will travel. The time to send each of the three groups should be constantly updated based on current send rates. A queue can only be a member of one of these groups at a time. This is important, otherwise the ‘fUpdateLatency’ would be difficult to calculate. The ‘fLatencyFromStream’ is calculated the same way as ‘fUpdateLatency’, except all nodes in a data stream will not add the ‘fLatencyFromStream’ value from another node when they pass their ‘fLatencyFromStream’ onto directly connected nodes. For example, if node A is in the data stream, and its time to update the group which the particular queue is in takes 3 seconds, it will tell all directly connected nodes that it is 3 seconds from the data stream. Alternatively, it could tell all directly connected nodes that it is 0 seconds from the data stream. If a queue needs to move from a high frequency update to a low frequency update, we'll change its reported ‘fUpdateLatency’ latency number to match the lower frequency group, but keep the item in the high frequency group for three updates cycles before actually moving it to the lower frequency group. If a node becomes aware of a new queue, it will place that queue at the end of the list of queues to update in one of three groups it belongs to in the second group of throttled updates. Possible Uses These are examples where this invention could be used. These examples are not intended to limit the use of the invention. 1. Used in communication networks it would enable network topography to take unlimited structures 2. Used in cell phone networks it would remove the need for current ‘cells’ structure that needs to hand off a moving cell phone to the next communications tower. 3. Used in a grid computing environment to help eliminate hotspots and deal with failed nodes. 4. Used by utilities with the software enabled in all electrical appliances such appliances could be turned on or off from a central command centre in order to achieve system load management 5. Used in computing it would enable multiple interconnected CPUs or computers to be linked in order to exchange messages for applications such as grid computing, mass storage or super-computing environments which applications are currently constrained by the lack of flexible, dynamic message routing capability. 6. Used in military applications it would enable every soldier and every piece of equipment in a theatre of combat to be in constant communication across a continually changing topographical structure and enable the network to continue regardless of elements being removed or destroyed or added. 7. Used to form discrete network groups either in isolation from or as a subset of larger networks it would enable any group to form its own network at any time. 8. Used in traffic management it would enable motor vehicles equipped with this software and with communications ability to coordinate their highway interaction for greater efficiency or safety or highway traffic management facilitation. 9. Used in traffic management of traffic signals it would enable all traffic lights to communicate with traffic management computers and with each other for greater effectiveness in managing traffic flows, and enable traffic signals to be added or deleted from the system with no need for any software administration to the system. 10. Used as a ‘master network’ it could become the communication utility for a community or region, providing virtually unlimited capacity and back-up resources because every participant in the network could provide linkage to the whole network and the sum of its resources. 11. Used to manage a computing centre the software would add or subtract machines and applications and administer and monitor the centre without human intervention and without any need to curtail or cease operations while doing so. 12. Used within an electrical energy grid this software could be used to integrate generating, transmission and consumption to deal with both ordinary changes and untoward events by making decisions based on predetermined criteria and acting immediately, 13. Used to enable remote computing by dynamically linking users and remote sites with no human intervention. 14. Used in air traffic control by managing and coordinating aircraft, air traffic and ground resources 15. Used to coordinate and network varying communications technologies such as wireless, land line, satellite, computer and airborne systems 16. Used to create efficient routes for the physical delivery of goods to various destinations, such routes able to be altered dynamically for varying circumstances such as traffic pattern changes, additions or deletions to the route destinations. 17. Used as a mathematical tool similar to biological computing for solving multiple simultaneous computations to find a correct solution, especially to complex problems that involve many criteria. The above-described embodiments of the invention are intended to be examples of the present invention and alterations and modifications may be effected thereto, by those of skill in the art, without departing from the scope of the invention which is defined solely by the claims appended hereto.

<SOH> BACKGROUND OF THE INVENTION <EOH>Networked devices are now an extremely important aspect of our social fabric. The public switched telephone network (“PSTN”) is perhaps the first example of a ubiquitous network of telecommunication devices that changed the way people interact. Now, mobile telephone networks, the Internet, local area networks (“LAN”), wide area networks (“WAN”), voice over internet protocol (“VOIP”) networks, are widely deployed and growing. It is trite to say that each of these devices need to be able to reach each other in order to fulfill networking functions. With the PSTN, a system of telephone numbers is employed, including country codes, area codes, local exchanges, etc. At least in North America, the explosion of telephonic devices has stretched the standard ten digit number scheme. With the Internet, the Internet Protocol Version 4 (“IPV4”) promulgates a system of Internet Protocol (“IP”) addresses to identify points on the Internet, and thus each networked device has an address making it reachable on the Internet. Due at least in part to the limited length of the IPV4 address field, IP addresses can bear little geographic relationship to their physical location. As a result, routers and routing tables throughout the Internet are extremely bloated, increasing complexity in traffic routing and increasing network latency. IPV6 offers potential relief addresses, but the upgrade to IPV6 is expected to be slow. In very general terms, many prior art network architectures rely on routing devices to maintain addresses and locations of the devices throughout the network. Such routing devices are essentially traffic cops, routing traffic along appropriate pathways. Such architectures become clumsy and awkward as the networks grow. Various “router-less” network architectures have been proposed. Some of these architectures are referred to as peer-to-peer networks, while others are referred to as ad-hoc networks. Regardless, these prior art architectures also tend to suffer from scaling and/or other limitations. One attempt to improve network architectures is Ad Hoc On Demand Distance Vector (“AODV”). AODV is a reactive protocol that uses a broadcast flood in order to establish a new connection or fix a broken connection. AODV is described in detail in the Internet Engineering Task Force (“IETF”) document found at http://www.ietf.org/rfc/rfc3561.txt. While AODV has the advantage of being able to easily organize nodes into an ad-hoc network one of the problems it has is that the maximum network size is extremely limited. Another attempt to improve network architectures is ‘Destination Sequenced Distance Vector’ (“DSDV”). DSDV is a proactive protocol that uses a constant flood of updates to create and maintain routes to and from all nodes in the network. A detailed description of DSDV is found at http://citeseer.ist.psu.edu/cache/papers/cs/2258/http:zSzzSzwww.srvloc.orgzSzcharliepzSz txtzSzsigcomm94zSzpaper.pdf/perkins94highly.pdf or http://citeseer.ist.psu.edu/perkins94highly.html. While DSDV has the advantage of providing loop free routing it has the disadvantage of a only working in small networks. In large networks the control traffic easily exceeds the available bandwidth. Another attempt to improve network architectures is ‘Optimized Link State Routing’ (“OLSR”). OLSR is a proactive protocol that attempts to build knowledge of the network topology. A detailed description of OLSR can be found in this IETF draft http://hipercom.inria.fr/olsr/draft-ietf-manet-olsr-11.txt. While OLSR has the advantage of being a more efficient link state protocol it is still unable to support larger networks. Another attempt to improve network architectures is ‘Open Shortest Path First’ (“OSPF”). OSPF is a proactive link state protocol that is used by some internet core routers. A detailed description of OSPF can be found in this IETF draft http://www.ietf.org/rfc/rfc1247.txt. While OSPF allows core internet routers to route around failure is has limitations on the size of networks it is able to support. Despite the differences between AODV, DSDV, OLSR and OSPF they all share some, of the same problems—e.g. the difficulty of scaling past a few hundred nodes. This limitation occurs because as the network grows, the amount of control traffic required grows much faster. Rapidly, the amount of control traffic needed will exceed the capacity of the network In general, prior art network architectures do not provide the good scalability, nor do they provide the ability to allow low capacity devices to fully interact with the larger network, and in mobile environments, prior art architectures do not always provide seamless mobility.

<SOH> SUMMARY OF THE INVENTION <EOH>It is an object of the present invention to provide a novel system and method for networking that obviates or mitigates at least one of the above-identified disadvantages of the prior art. A first aspect of the invention provides a network that comprises a plurality of nodes and a plurality of links interconnecting neighbouring ones of the nodes. Each of the nodes are operable to maintain information about each of the nodes that are within first portion of the nodes. The information includes: a first identity of another one of the nodes within the first portion; and for each first identity, a second identity representing a neighbouring node that is a desired step to reach the another one of the nodes respective to the first identity. Each of the nodes are operable to determine a neighbouring node that is a desired step to locate the nodes in a second portion of the nodes that are not included in the first portion. In a particular implementation of the first aspect, the determination is based on which of the neighbouring nodes most frequently appears in each second identity. In a particular implementation of the first aspect, each of the nodes is operable to exchange the information with its neighbouring nodes. In a particular implementation of the first aspect, each link has a set of service characteristics such that any path between two of the nodes has a cumulative set of service characteristics; and wherein the desired step is based on which of the paths has a desired cumulative set of service characteristics. In a particular implementation of the first aspect, the service characteristics include at least one of bandwidth, latency and bit error rate. In a particular implementation of the first aspect, the nodes are at least one of computers, telephones, sensors, personal digital assistants. In a particular implementation of the first aspect, the links are based on at least one of wired and wireless connections. In a particular implementation of the first aspect, a network core is formed between neighbouring nodes that determine each other's desired step to reach the nodes within the second portion. In a particular implementation of the first aspect, each node is operable to instruct other nodes between the core and the node to maintain information about the node. In a particular implementation of the first aspect, each node is operable to request information about the nodes within the second portion; each node being operable to make the request to the other nodes between the core and the node. One advantage of the present invention over the prior art is that the network architecture taught herein allows for large scale self-organizing networks. This feature is enabled, for certain embodiments, because very few nodes in the network need actually have knowledge of the entire network. Collectively, all nodes in the network have knowledge of the entire network, and nodes that are unaware of other nodes, but which need find such other nodes, are provided with means of locating those other nodes by seeking such knowledge from other nodes in the network having relevant knowledge. For these and other reasons, the present invention is a novel self-organizing network architecture that enables for substantially larger self-organizing networks than prior art self-organizing network architecture. Thus, a second aspect of the invention provides a self-organizing network comprising at least 2,000 nodes interconnected by a plurality of links. A third aspect of the invention provides a self-organizing network comprising at least 5,000 nodes interconnected by a plurality of links. A fourth aspect of the invention provides a self-organizing network comprising at least 10,000 nodes interconnected by a plurality of links. A fifth aspect of the invention provides a self-organizing network comprising at least 100,000 nodes interconnected by a plurality of links.

20070405

20110614

20071213

82569.0

H04L1228

ZHAO, WEI

NETWORK ARCHITECTURE

SMALL

ACCEPTED

H04L

ACCEPTED

Safe Storage of Volatiles

The present disclosure is related to methods and apparatus that provide safe storage of volatile compounds or elements, utilizing storage configurations that take advantage of the diffusibility and release characteristics of cell-based materials, such as foam materials.

1. A method for storing volatiles under pressure, comprising; providing a storage apparatus, wherein said storage apparatus includes an outer portion and a foam component, wherein said foam component is contained within an inner space defined by said outer portion; connecting said storage apparatus to a source for providing a volatile; and conducting said volatile from said source into said storage apparatus. 2. The method of claim 1, wherein said foam component includes closed cells with low, but nonzero, cell-wall permeability. 3. The method of claim 1, wherein said volatile is at least one of a liquid or gas or combination thereof. 4. The method of claim 1, wherein said volatile is at least one of ammonia, butane and propane. 5. The method of claim 1, wherein at least a portion of a surface of said foam component is sealed. 6. An apparatus for storing volatile compounds, comprising; an outer portion, said outer portion defining an inner volume; and a foam component, wherein said foam component is contained within an inner volume defined by said outer portion. 7. The apparatus of claim 6, further comprising means for introducing at least one volatile compound into said inner volume. 8. The apparatus of claim 6, wherein said foam component includes closed cells. 9. The apparatus of claim 6, wherein said outer portion is composed of at least one of a metal, alloy and plastic. 10. The apparatus of claim 6, wherein said foam component has a void fraction of about greater than 60%. 11. The apparatus of claim 6, further comprising a sealing component disposed upon at least a portion of said foam component. 12. The apparatus of claim 6, wherein said foam component is provided with at least one channel. 13. An apparatus for storing volatile compounds using a foam component whose geometry is cylindrical, spherical, or planar. 14. The apparatus of claim 13, wherein several such storage apparatus can be manifolded together to increase volatile delivery rate, wherein a safe delivery rate of each device is maintained. 15. The apparatus of claim 13, wherein, the storage apparatus is arranged in a stacked fashion, thus providing cartridges and is further enclosed in an outer enclosure containing suitable inlet and outlet fittings. 16. An apparatus of claim 14, wherein, said manifoldable devices allow for charging of volatiles of one or more cartridges or storage apparatus while allowing discharge of volatile from one or more other cartridges or storage apparatus. 17. An apparatus of claim 14, wherein a provided configuration permits replacement of one or more cartridges or storage apparatus while one or more other cartridges or storage apparatus are delivering volatiles to an end-use system. 18. An apparatus of claim 6 wherein said apparatus is air cooled or liquid cooled to improve charging rates. 19. An apparatus of claim 6 wherein the apparatus can be air cooled or liquid cooled to improve volatile charging rates. 20. The apparatus of claim 17, wherein said end-use system is a hydrogen generator. 21. The apparatus of claim 17, wherein said end-use system is a fuel cell power system.

RELATED APPLICATION This application is related to and claims priority and benefit of U.S. Provisional Application No. 60/546,304, filed Feb. 19, 2004, entitled “Safe Storage of Volatiles”. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT The invention was made with Government support under contract No. DAAD19-00-C-0015 by the Department of Defense. The Government has certain rights in the invention. BACKGROUND 1. Field of Endeavor The invention relates generally to safe storage of compounds, in particular volatile compounds. In one aspect, the present disclosure relates to the use of foam-cell material to store volatile compounds. In another aspect, the present disclosure provides for the safe storage of a source from which hydrogen may be extracted. 2. Description of Related Art Recent improvements in the design and manufacture of hydrogen/air fuel cells have increased interest in the use of fuel cells as a replacement for batteries and other power supplies (e.g., vehicle engines). Because hydrogen/air fuel cells can operate on very energy-dense fuels and are quiet and efficient, fuel-cell-based power supplies are considered a promising future power source. Many fuel cells operate using hydrogen gas for fuel, and oxygen (typically from air) as an oxidant. Unfortunately, reliable, convenient, and compact hydrogen sources do not yet exist, so fuel cells have yet to receive widespread commercial or military use. Fuel cells, however, represent relatively mature technology and are commercially available. As discussed above, there is a great need and interest in hydrogen generators, including compact hydrogen generators, that extract hydrogen gas from a source. Examples of such sources/volatiles from which hydrogen may be obtained include, but are not limited to, butane, propane and anhydrous ammonia. As can be appreciated, use of hydrogen generators for providing hydrogen gas will likely be restricted unless the sources of hydrogen can be stored in a safe manner. For example, if anhydrous ammonia is the hydrogen source, a method and apparatus for storing ammonia must reduce and/or minimize the potential for a dangerous ammonia release if the integrity of the storage apparatus is compromised. Successful development of a safe ammonia-storage tank is beneficial because it facilitates rapid deployment of ammonia-based hydrogen sources for compact fuel-cell power supplies. Several approaches are available for hydrogen generation and/or storage. These include hydrocarbon and methanol fuel reforming, hydrogen absorption into metal hydrides, hydrogen-generating chemical reactions, and ammonia decomposition (Blomen, L., and M. N. Mugerwa. 1993. Fuel Cell Systems. Plenum Press, New York; Bloomfield, D. P., V. J. Bloomfield, P. D. Grosjean, and J. W. Kelland. 1995. Mobile Electric Power. Analytic Power Corp., NTIS Report ADA296709). Adsorbent-based approaches offer reduced storage pressure, but often at a cost of vastly increased storage volume and mass. Ammonia decomposition and ammonia-based chemical reactions are attractive methods for hydrogen generation because the required chemical reactors tend to be relatively small, simple, and easy to control. Ammonia decomposition has received relatively little attention, however, because of ammonia's toxicity and foul odor, and because it is generally not economical for power production except in remote, low-power applications (Appleby, A. J., and F. R. Foulkes. 1989. Fuel Gel/Handbook Van Nostrand Reinhold, New York). In spite of these drawbacks, hydrogen from ammonia is attractive for at least two reasons: (I) The usable hydrogen per kilogram of fuel is relatively high; and (2) ammonia-based fuel-cell systems can be deployed much sooner than the more complicated hydrocarbon-based fuel reformers. Before ammonia-based hydrogen generators will gain acceptance, the problem of safe ammonia storage must be addressed. Ammonia is a toxic gas that can rapidly damage the eyes and respiratory tract upon exposure to concentrations in the range of about 500-1000 ppm. Exposure to higher concentrations (>5000 ppm) even for short periods can lead to respiratory failure and death (Nielsen, A. 1995. Ammonia: catalysis and Manufacture. Springer-Verlag. London). An ammonia-based hydrogen generator operating in an enclosed environment must not have the potential for rapid ammonia release, as this may be harmful or even deadly for surrounding personnel. The ammonia-based hydrogen generators currently under development (e.g., Powell, M R. M S Fountain, C J Call, A S Chellappa. 2002. “Ammonia-Based Hydrogen Generation for Fuel Cell Power Supplies.” Army Science Conference 2002, Orlando, Fla. Dec. 2-5, 2002) employ lightweight storage tanks made from either aluminum or titanium. These tanks have a mass of approximately 120 g and an ammonia storage volume of about 0.7 liters. The tanks are designed to withstand >1000 psig to ensure they do not burst in response to ammonia vapor pressure, which can exceed 250 psi at temperatures greater than 40° C. However, the storage tanks are not designed to withstand punctures from sharp objects or projectiles such as bullets. Further, there is the possibility for failure of tubing and/or reactor components downstream of the ammonia-storage tank, all of which could result in rapid release of ammonia. Before ammonia-based hydrogen sources can be widely marketed, the ammonia storage tanks must be improved to guard against rapid ammonia release in the event of tank puncture. Currently, safe storage of ammonia (and other selected hazardous liquefied gases) requires use of relatively heavy, thick-walled tanks or loading the ammonia onto high-capacity adsorbents. The storage units in both approaches are heavy and result in undesirable increases in mass of end-use systems such as hydrogen generators for fuel cells. For example, an ammonia-storage system with a 500-gram capacity will have a total mass of about 2000 g or more (capacity<20 wt.-%) if a standard storage tank is used. If an adsorbent is used instead, the mass of adsorbent is expected to be at least three times the mass of ammonia stored, so the resulting storage system will have a mass greater than 2000 g (capacity<20 wt.-%). Monolithic storage structures for gases have received relatively little attention in the literature. This is largely because there is not a perceived need for the ability to store small quantities of toxic or flammable gases under pressure in a small volume. Propane and butane are sold commercially in small quantities as liquids, but safety concerns are mitigated through the use of a heavy storage vessel and warnings regarding indoor storage and use of the fuel. As compact, lightweight fuel-cell power systems become more prevalent, however, greater emphasis is expected on the need to safely store small quantities of these materials for indoor use. Some work along these lines has been performed at the Oak Ridge National Laboratory as part of a program to develop passenger vehicles that can run on natural gas. Storage of the natural gas is the principal obstacle to these vehicles because natural gas cannot be liquefied under ambient temperature conditions. Burchell and Rogers (2000) (Burchell, T. and M. Rogers. 2000. “Low Pressure Storage of Natural Gas for Vehicular Applications.” SAE Technical Paper Series. 2000-01-2205. SAE, Warrendale, Pa.) report on a monolithic storage structure utilizing adsorption of natural gas. Adsorbent fibers are configured into a monolithic block with high adsorption capacity and high thermal conductivity, which are both desirable properties for the vehicle application (high thermal conductivity allows rapid filling of the adsorbent without overheating). In particular, this prior art approach, however, is not likely to be of use for safe ammonia storage. Adsorbent-based approaches suffer from relatively low ammonia storage density and the need to provide heat to desorb the ammonia from the adsorbent. Further, this adsorbent monolith has a high thermal conductivity, which is counter-productive for safe ammonia storage. Low thermal conductivity of the storage matrix is preferred to help retard vaporization of volatiles, for example ammonia, from the monolith. If heat cannot quickly reach the vapor-liquid interface, volatilization of ammonia will be slowed. SUMMARY We have examined a variety of methods for improving the safety of storing volatile compounds. One aspect of the disclosure involves storing the volatile compound inside a low-permeability, high-void-fraction, monolithic structure such as a closed-cell foam. In particular embodiments, such foam may be a ceramic foam. In another aspect, the volatile can be at least one of ammonia, butane and propane. This approach offers very high storage density, compact size, and a controlled release rate for the volatile even in the event of tank puncture. Rapid release of the volatile from the foam monolith is controlled by thermal and mass-transfer effects. To escape the monolith, the volatile must permeate through the cell walls to near the surface of the monolith. Experiments described in the disclosure provide evidence that this is a viable concept. Tests demonstrate that closed-cell foam materials offer a promising method for improving the safety of volatile compound storage, particularly for ammonia storage. In an aspect, the present disclosure provides for the safe storage of ammonia utilizing monolithic, closed-cell foam materials, which offer the desired characteristics of compact and lightweight ammonia storage with relatively little safety risk. Lightweight, closed-cell foam materials will be used to fill an ammonia-storage tank and thereby reduce the rate of ammonia release in the event of tank failure. The disclosed closed-cell foam approach results in very little increase in mass and volume over that of the pure liquid ammonia. In addition to storage of ammonia, this approach may have other applications related to the safe storage of other toxic and/or flammable liquefied gases such as butane and propane. Possible alternative applications of such storage configurations will make possible personal heaters for skiing and other cold-weather activities. In accordance with one aspect of the disclosure, a method for storing volatiles under pressure is disclosed that includes providing a storage apparatus where the storage apparatus includes an outer portion and a foam component. The foam component is contained and disposed within an inner space defined by the outer portion. The storage apparatus is then connected to a source, such as a tank, for providing a volatile compound and the volatile is then conducted from the source into the storage apparatus, whereby the voids of the foam component have the volatile compound conducted thereto. In particular aspects, foam component includes closed cells with low, but nonzero, cell-wall permeability. The volatile compound can be at least one of a liquid or gas or combination thereof. Exemplary volatiles can include, but are not limited to, at least one of ammonia, butane and propane or any combination thereof. In particular embodiments, at least a portion of a surface of the foam component is sealed. In accordance with another aspect of the disclosure, an apparatus for storing volatile compounds is disclosed, comprising an outer portion, the outer portion defining an inner volume of the apparatus, and a foam component, where the foam component is disposed and contained within the inner volume defined by said outer portion of the apparatus. The apparatus comprises means for introducing at least one volatile compound into the inner volume containing the foam component. In particular embodiments, the foam component includes closed cells. In some embodiments the outer portion of the apparatus is composed of at least one of a metal, alloy or plastic or any combination thereof. In one aspect, the foam component utilized and disclosed herein has a void fraction of about greater than about 60%. In some embodiments, the apparatus further comprises a sealing component disposed upon at least a portion of the foam component. A flexible elastomer can be utilized as a sealing component, for example. In particular embodiments, the foam component is provided with at least one channel. In another aspect, an apparatus for storing volatile compounds in accordance with the teachings of the present disclosure employs a foam component whose geometry is cylindrical, spherical, or planar. In some embodiments, apparatus can be composed of several disclosed storage apparatus which can be manifolded together to increase volatile delivery rate, wherein a safe delivery rate of each device/apparatus is maintained. In some embodiments, the storage apparatus is arranged in a stacked fashion, thus providing cartridges and is further enclosed in an outer enclosure containing suitable inlet and outlet fittings. In particular embodiments, manifoldable devices allow for charging of volatiles of one or more cartridges or storage apparatus while allowing discharge of a volatile from one or more other cartridges or storage apparatus. In some such embodiments, a provided configuration permits replacement of one or more cartridges or storage apparatus while one or more other cartridges or storage apparatus are delivering volatiles to an end-use system. In particular embodiments, the disclosed apparatus can be air cooled or liquid cooled to improve charging rates. In another aspect, the apparatus and methods disclosed herein can be utilized and provided in accordance with and part of an end-use system. An exemplary end-use system can include a hydrogen generator. Another exemplary end-use system is a fuel cell power system. The teachings of the present disclosure provides for storage of hazardous, liquefied gases in a closed-cell foam material. Release of gas/liquid from the monolith is restricted by the need for the gas to diffuse through the closed cells. Because rapid release is prevented, storage safety is greatly improved. The mechanical strength of the foam monolith provides pressure resistance to the liquefied gas pressure. A tank can be formed by sealing the external surface of the monolith, resulting in a storage system that is very lightweight and safe. Control of the gas release rate can be achieved not only via adjusting foam properties, but also by adjusting the foam monolith geometry. For example, holes can be drilled into the monolith to provide for an increase in surface area that will increase the gas release rate. Alternatively, portions of the monolith surface can be sealed with an impermeable layer thereby decreasing the gas-release rate. The gas release process is approximated by diffusional loss, so geometries expected to increase the rate of gas diffusion out of a monolith (e.g., those with high surface-area-to-volume ratios) will also increase the rate of gas release from the foam-based monolithic gas storage structure. In addition to markets for safe storage of ammonia, niche markets for safe storage of small quantities of other hazardous and flammable liquefied gases are anticipated. Most butane-powered consumer devices are currently not allowed onboard commercial aircraft due to the potential for an in-flight fire. Development of a method to restrict butane release rate in accordance with the teachings of the present disclosure, for example, may result in some of the devices being allowed. Other applications include personal heaters, which are not widely marketed in part because of the risks associated with carrying a pressurized flammable gas in proximity to a flame or catalytic burner. Elimination of the possibility for catastrophic failure of volatile storage apparatus, such as a butane/propane storage tank, would greatly improve the commercial viability of these devices. Further, when hydrocarbon-based fuel reformers become available, safe storage media will be a priority for compact applications designed for indoor use. FIGURES Descriptions of exemplary embodiments are provided and reference made to the accompanying figures which form the part thereof, and in which are shown by way of illustration of specific embodiments. It is to be understood that other embodiments may be utilized and structural and functional changes may be made without departing from the scope of the present disclosure. FIG. 1 is an exemplary embodiment of a volatile storage apparatus in accordance with one aspect of the disclosure; FIG. 2 depicts exemplary samples of useful foams; FIG. 3A is an exemplary testing apparatus in an open configuration; FIG. 3B is the exemplary testing apparatus of FIG. 3A in a closed configuration; FIG. 4 depicts exemplary ammonia and butane release data; FIG. 5 depicts an example of ammonia release from exemplary H200 foam; FIG. 6 depicts predicted internal pressure resistance; FIG. 7 is a chart showing the effect of covering a foam surface on a release rate; FIG. 8 depicts particular components of an exemplary PVC tank storage apparatus; FIG. 9 depicts steel and PVC embodiments, in accordance with the teachings of the present disclosure; FIG. 10 shows an ammonia fill rate for a PVC tank embodiment; FIG. 11 is a comparison of exemplary ammonia release rates for full and one-quarter-full foam monoliths; FIG. 12 reports exemplary release rate data for a steel storage apparatus embodiment; FIG. 13 reports exemplary release rate data for a PVC storage apparatus embodiment; FIG. 14 illustrates exemplary volatile release rates in accordance with an aspect of the present disclosure; and FIG. 15 illustrates exemplary release of propane in accordance with the present disclosure. DETAILED DESCRIPTION The foregoing is a description of preferred embodiments and has been presented for the purpose of illustration and description. It is not intended to be exhaustive or to limit the present disclosure in any way. Many modifications and variations are possible in the light of the teachings provided herein. Turning to FIG. 1, an exemplary configuration of a closed-cell-foam-based volatile storage vessel is depicted. In this exemplary embodiment, the volatile stored is ammonia. The closed-cell monolith 2 (foam) is surrounded by a flexible elastomer 4, such as Buna Nitrile or Neoprene (synthetic rubber based on polychloroprene, as known in the art), which are compatible with ammonia. The elastomer layer/sheet 4 protects the monolith 2 against damage from vibration and fills the gap between a titanium tank shell 6 and the monolith 2 to prevent accumulation of liquid ammonia outside the monolith 2. Small-diameter holes, such as fill/drain hole 8, penetrate through the monolith 2 to allow a relatively stable release rate from the monolith 2 and to facilitate filling the monolith 2 with liquid ammonia. A closed-cell foam with high void fraction (e.g., 80% or higher) can be used for safe ammonia storage. Lower-void-fraction foams can also be used, but the resulting storage density will be reduced. An alternative embodiment involves coating a monolith 2 of closed-cell foam with an impermeable layer (e.g., bonded metal foil, epoxy, or fiberglass). The sealing layer can be very thin because it is well supported by the monolith 2. Even a very thin impermeable layer (e.g., 50 to 100 microns) will provide adequate pressure resistance. Because the layer can be so thin, the resulting mass of the storage system is very low. That is, the external enclosure, such as a titanium canister, can be eliminated. The closed-cell monolith approach, however, can store, for example, about 500 g of ammonia with perhaps about 200-400 g of monolith 2. The resulting system mass could be as low as about 750 g if the monolith surface is sealed using a thin, impermeable layer that obviates the need for an external metal enclosure, resulting in a storage capacity of about 67 wt.-%, which is more than a 3× improvement in capacity over prior art storage methods. Even if a thin-walled, metal storage tank is required, the resulting mass is expected to be less than about 1000 g, resulting in a storage capacity of at least 50 wt.-% which is more than a 2× improvement in capacity over prior art storage methods. An aspect of the present invention utilizes closed-cell monoliths for volatile compound storage, including ammonia storage. Liquid ammonia is stored inside the spherical cells of a high-void-fraction foam monolith. Release of ammonia is restricted by two effects. First, ammonia release is restricted by the cell walls; ammonia must permeate through the cell walls to escape the monolith. Proper selection of monolith properties and geometry allow control of the ammonia release rate. The targeted accidental release rate is about 0.18 g/min of ammonia, which should allow sufficient time for evacuation of personnel and/or execution of other safety protocols to ensure the safety of personnel and end-use equipment. Second, the foam serves to restrict heat flow through the ammonia so in the event of a sudden depressurization, a relatively small fraction of the ammonia will flash to vapor because heat from the bulk of the ammonia cannot be rapidly transported to the vapor/liquid interface where evaporation takes place. Closed-cell foam materials can withstand surprisingly high internal pressures without failure due to the effect of small curvature radii on pressure-induced tensile stresses. This effect is described by the Young-LaPlace equation, which is (Hiemenz, P C. 1986. Principles of Colloid and Surface Chemistry. 2nd ed. Marcel Dekker, Inc. New York): ΔP=(2σE)/R where ΔP is the pressure difference between the inside and outside of the spherical shell, σE is the elastic stress in the shell, and R is the radius of curvature of the sphere. For a constant ΔP, the resulting stress decreases in direct proportion to the reduction in radius of curvature. Most people have experienced the Young-LaPlace effect while inflating rubber balloons. The balloon requires considerable effort to begin the inflation even though the rubber is under relatively little tension (i.e., the rubber is not yet stretched). A high initial inflation pressure is required because the balloon's radius of curvature is small. As the balloon radius increases, the elastic tension in the rubber surface also increases, but the pressure required to maintain the tension decreases. Somewhat surprisingly, the internal pressure of a half-inflated balloon is higher than that of a fully inflated balloon. The implication of the Young-LaPlace equation for foam-based storage of volatiles, including ammonia, is that even very thin (and relatively fragile) cell walls can resist the >100 psia vapor pressure of ammonia if the cells are small. This is fortunate because to keep the ammonia storage density high, a high void fraction (about >80%) foam is desired that will necessarily have relatively thin cell walls. The required cell size depends on the strength of the cell walls, but typically cell diameters must be less than about 5 mm and preferably less than 0.5 mm. A variety of closed-cell materials have been studied. In one embodiment, the exemplary DIAB Group (DeSoto, Tex.) Divinycell H200 foam (H200), was selected for further testing and use. The void spaces in closed-cell insulating foams are often filled with low-thermal-conductivity gases to improve overall thermal performance. Over time, these gases can diffuse out of the insulation and air gases (e.g., nitrogen, oxygen, and water vapor) diffuse into the insulation. The rate at which this gas exchange takes place determines the useful life of the closed-cell foam insulation. Pilon et al. (Pilon, L., A. G. Fedorov, and R. Viskanta. 2000. “Gas Diffusion in Closed-Cell Foams.” Journal of Cellular Plastics. 36:451-474) developed a mathematical model of gas release from insulating foams in which the effective diffusivity of the diffusing gas is related to the foam void fraction and cell size as well as the diffusion rate of the gas through the continuous phase of the foam. Pilon's derived expression for the effective diffusivity (Deff) is: D eff = 1 n ⁢ ( 1 + ϕ 1 - ϕ 3 ) ⁢ D c , 0 ⁢ exp ⁡ ( - E c R ⁢ ⁢ T ) where n is the number of cells across the foam thickness in the direction of the diffusion flux, φ is the void fraction, Dc,0 is the diffusivity of gas through the continuous phase, Ec is an activation energy term, R is the gas constant, and T is absolute temperature. As expected, decreasing the cell size (i.e., increasing n) or decreasing the void fraction results in a decrease in the effective diffusivity. The H200 foam tests prove the concept of controlling the ammonia release rate to the desired levels through the use of a closed-cell foam material. Storage of ammonia, as well as other volatiles, in closed-cell monolithic foams is desirable and illustrated for the following exemplary reasons: 1) High volumetric density: Ammonia can be stored inside the closed-cell foams with very little increase in overall volume. With void fractions of about 0.80 and higher, the volume increase is only about 25% over that of liquid ammonia. 2) High mass density: Because the ammonia is stored in a lightweight matrix, there is relatively little mass increase compared with storage of liquid ammonia in an empty steel-type tank. When loaded to 0.45 g NH3/cm3 of foam, the H200 foam results in only a 45% mass increase compared with liquid ammonia. Since the density of the H200 foam is 0.2 g/cm3, the storage capacity of the foam is nearly 70 wt.-%, which is approximately seven times greater than the 10 wt.-% maximum capacity typical of prior-art, adsorption-based, ammonia storage methods. 3) Simple and Versatile: Storage of ammonia in a foam material does not require heat (other than ambient) to supply ammonia to ammonia-based hydrogen generators, for example. Further, ammonia can be delivered at high pressure (about 70 to 100 psig) from the foam monolith so there is sufficient pressure available to supply an ammonia-decomposition reactor with an integral hydrogen-separation membrane. Ammonia at the desired pressure can be supplied by incorporating a suitable throttling valve or pressure regulator in the vessel or in the end-use system. The development of a safe volatile storage system, is described below. Identification of Candidate Closed-Cell Foam Materials A variety of different materials were identified as possible volatile compound storage media, for use as, in one example, ammonia-storage media. The general classes of materials examined are listed below. Samples of each material were tested to determine their ability to restrict the release of ammonia. The materials collected for this effort included: Alumina Ceramic Foam: Six different alumina foam formulations were obtained from Cellaris Ultralight Ceramics, Ltd. (D.N. Misgav, Israel). These foams are formed via a patented process that involves binding together hollow spheres of alumina. Silicon Oxycarbide Foam: Professor Palo Colombo (Dept. of Material Science, University of Bologna, Italy) has developed a technique for creation of lightweight foams using silicon oxycarbide ceramics. These foams have a closed-cell structure with small “window” openings in the cells that allow gas flow between adjacent cells. Aluminum Foam: Samples of closed-cell 6061 alloy aluminum foam were obtained from Porvair Advanced Materials (Hendersonville, N.C.). Aluminum foam samples were also obtained from Cymat (Mississauga, Ontario, Canada), Fraunhofer USA (Newark, Del.), and Gleich (Kaltenkirchen, Germany). Syntactic Foam: Samples of SynSpand® were obtained from Loctite Aerospace (Bay Point, Calif.). Synspand® is a closed-cell expanding syntactic foam for custom density-to-strength ratios in honeycomb core and cavity filling. This product is supplied in thin-film sheets which are expanded and cured by controlling temperature and ramp rate. Glass Microspheres with Ceramic or Cementitious Binders: A variety of high-void-fraction, foam-like materials were prepared from mixtures of glass and plastic micro-balloons with ceramic particles or cementitious binders such as portland cement and plaster of Paris. Glass Foam: Samples of Pittsburgh Corning FoamGlas HLB1600 insulation were obtained. This material is used as a high-temperature insulator, has good chemical resistance, high void fraction, and low density (0.163 g/cm3). Polymeric Foams: Structural foam materials made from a variety of polymeric materials were also tested. The DIAB H200 foam, which we have selected as an exemplary foam in various embodiments disclosed herein, is a structural polymeric foam. Its mechanical properties are similar to those of wood, yet its density is only 0.2 g/cm3. Ceramic/Carbon Foam: Mixtures of ceramic and carbon particles were fired to 1100° C. under nitrogen to sinter the ceramic particles without burning away the carbon. The samples were then fired at 500° C. under air to burn away the carbon, thereby leaving a ceramic foam with high void fraction. Graphite Foam: Samples of graphite foam were obtained from Poco Graphite, Inc. (Decatur, Tex.). In excess of 100 samples were obtained from vendors or prepared. FIG. 2 shows some of the samples collected for this effort, provided in various geometric forms for testing. In some cases, butane or propane was used for gas-release tests. A sample-testing apparatus 10, provided having two halves threaded to fit each other, was designed and built from 6061 aluminum alloy, which has adequate ammonia corrosion resistance. This test cell is shown in FIGS. 3A and 3B. The cube-shaped sample chamber 12 is 3 cm on each edge. Gas is allowed to escape through a ⅛″-dia hole (not shown) in the top of the unit. This hole can be closed using a valve 14, such as a three way valve, for example, shown on the top of the sample testing apparatus 10 in FIG. 3B (some exemplary foams 11 are illustratively represented). Each foam sample was cut to fit inside the 3-cm cubic volume sample chamber inside the test apparatus. Once the sample was secured inside the test apparatus, air was pumped out of the apparatus using a vacuum pump. Pressurized butane or ammonia was then connected to the 3-way valve, such as valve 14, to infuse the foam sample with gas/liquid. The mass of the unit was periodically measured to determine the mass of ammonia or butane infused into the simple. Once the mass was stable (implying the foam monolith was filled), the apparatus was inverted and drained of excess liquid without releasing a significant quantity of gas. The test apparatus was then placed on an electronic balance and the valve opened to the atmosphere. As the gas escaped, the resulting mass loss was observed and recorded. FIG. 4 shows the test results for a variety of exemplary foam monolith samples. The exemplary (polyvinylchloride “PVC”) polymeric foam, DIAB H200 foam (from DIAB Technologies, DeSoto, Tex.), exhibited a much slower gas-release rate than any other material tested. The H200 data were collected using ammonia. Comparing the experimentally observed release rates with the numerical-model predictions, the effective diffusivity of most samples ranged from 10−5 to 10−7 m2/s. The H200 foam, however, has an estimated effective diffusivity of only 1.8×10−9 m2/s. The ammonia-release data for the DIAB H200 sample shown in FIG. 4 indicates an initial ammonia loading of 0.20 g NH3 per cm3 of foam. Other tests (e.g., tests shown in FIG. 7) have demonstrated higher ammonia-loading densities. Based on the known void fraction of the H200 foam (0.84) and the density of liquid ammonia at room temperature (0.6 g/cm3), it should be possible to achieve a loading of 0.5 g NH3/cm3. This has been confirmed experimentally where loadings of up to 0.50 g NH3/cm3 have been achieved. Predicted ammonia-storage densities based on ammonia loadings of 0.25 and 0.45 g NH3/cm3 are provided. Several foams were tested using both butane and ammonia. The release rate (g/min) was found to be similar for both gases. Ammonia has a higher vapor pressure than butane, but it also has a higher heat of vaporization, which serves to slow the release. These two effects appear to largely cancel each other out. The H200 foam has very attractive ammonia-release characteristics; its effective diffusivity is low enough to prevent rapid ammonia release, yet high enough to allow the target feed rate of about 0.12 g/min to about 0.18 g/min. Of course, alternative applications will have different target rates, so that a release rate (g/min) with a reasonable monolith surface area can be selected, that is, a surface area is provided/selected in conjunction with a selected volatile to provide a desired release rate. The H200 foam also appears to have adequate chemical resistance for the ammonia-storage application. H200 is composed of polyvinyl chloride (PVC) and polyurea. DIAB Technologies (DeSoto, Tex.) has conducted “solvent resistance” tests in which samples of H200 foam were exposed to various solvent atmospheres for 28 days. Tests using ammonia indicated the foam compressive strength decreased by about 17% over this period. This result implies ammonia affects the foam matrix, but the relatively small 17% decrease implies the effect is minor. Testing has not revealed evidence for rapid degradation of the H200 foam upon exposure to ammonia. FIG. 5 shows the ammonia release-rate data for multiple tests using the same piece of H200 foam. Ammonia release was evaluated following exposure times ranging from 2 days to 140 days. After 140 days of exposure to liquid ammonia, the release rate was found to be roughly twice that of samples exposed for 25 days or less. The fact we do not observe a rapid degradation of the foam's ability to restrict ammonia release shows that a polyvinylchloride foam, such as H200 foam, can be used for safe ammonia storage for a period of at least several months. Thus far, all tests have been conducted at about room temperature (about 21-23° C.). Ammonia release is expected to be reduced at lower temperatures principally because the vapor pressure of the stored ammonia will be reduced. At 5° C., the ammonia vapor pressure is roughly half of the room-temperature value. The lower pressure driving force at lower temperatures is expected to reduce the ammonia release rate. The ammonia release rate depends on the interaction of the ammonia vapor pressure as well as its diffusivity and solubility in the PVC/polyurea that comprises the exemplary H200 foam. By similar reasoning, higher temperatures are expected to increase the ammonia release rate. As the temperature increases, however, it should be considered that there is the possibility the ammonia vapor pressure could exceed the mechanical strength of the foam and result in rupture of the cell walls. To evaluate this possibility, we calculated the tensile stress in the walls of a 0.3-mm-dia. hollow sphere which is the mean cell size in the exemplary H200 foam. The wall thickness was determined as a function of the foam bulk density, and the mechanical properties of PVC were applied (7000 psig tensile strength, 1250 kg/M3 density). The calculation results are shown in FIG. 6. The cells in the exemplary H200 foam (bulk density=200 kg/m3) are predicted to burst at 420 psig, which is equal to the vapor pressure of ammonia at 65° C. The H200 foam will likely experience failure at a pressure somewhat lower than 420 psig because of reduced foam strength at higher temperatures and the fact that the cells are not exactly spherical. If greater pressure resistance is required, however, other exemplary foams with bulk densities of up to 400 kg/M3 are available and may be utilized. As shown in FIG. 6, the pressure resistance of H400 foam (density of 400 kg/M3) is predicted to be more than twice that of the H200 foam (960 psig vs. 420 psig). It is useful to have control over the ammonia release rate via additional methods other than adjusting the foam properties (void fraction and cell size). Ammonia release from a foam monolith can be reduced simply by sealing a fraction of the monolith surface with an impermeable (or slightly permeable) barrier. This technique was demonstrated using a sample of H200 foam. FIG. 7 shows the ammonia release rate for H200 foam compared with the release rate from a similarly sized piece of H200 foam with half of the surfaces sealed with a 0.5-mm-thick layer of PVC. The PVC sheet was sealed to the H200 foam via a standard solvent-welding technique for PVC. The ammonia release rate from the uncovered foam is 2 to 3 times that of the foam with half of the surfaces covered. This result demonstrates the ammonia release rate can be adjusted downward simply by sealing a fraction of the monolith surface. Increasing the release rate can similarly be accomplished by using a monolith geometry with a higher surface-area-to-volume ratio such as a thin slab rather than a cube or sphere. A planar architecture for the ammonia storage foam, and subsequently the device, should permit more compact packaging into hydrogen generation units, for example. Such packaging should also lend itself well to high volume production, as the foams can be incorporated into a external box-type enclosure (as opposed to a cylindrical vessel) in a cartridge type fashion. Such a packaging method also leads to low cost and would allow for periodically swapping the spent cartridges out with a fresh one. Another important feature of the planar architecture of the storage device is stacking to enable scale-up of the storage device without violating the safe discharge rates (0.18 g/min for ammonia). As mentioned earlier, the targeted delivery rate of ammonia from the storage device is 0.18 g/min which is sufficient to power a 20 W to 30 W fuel cell power system. When the delivery rate of ammonia needs to be increased beyond the safe limit of 0.18 g/min per storage unit, for example when 1 g/min is required to power a 100-200 W fuel cell power system, several planar storage devices (about 5, for example) or cartridges can be arranged in a stacked fashion and manifolded together to supply the desired ammonia flow rate without violating the safe discharge rates for each cartridge. As mentioned earlier, one embodiment of the storage device allows the encapsulation of the foam in a non-permeable material. For practical use, it may be advantageous to add on an additional layer of safety by enclosing the encapsulated foam in a thin metal enclosure. When a stacked architecture is adopted, one metal enclosure may incorporate several encapsulated foam cartridges that leads to a compact, lightweight and safe storage device while permitting the flexibility to change the ammonia delivery rate to an end-use device such as a fuel cell power system, as desired. If the foam cartridge is not encapsulated but is enclosed in a metal enclosure directly, the stacking methods described above and benefits thereof would also be applicable. When the storage device is in a cylindrical vessel form, several vessels may be manifolded together to increase the delivery rate of ammonia without violating the safe delivery rate of each unit. When the storage device is a cylindrical vessel form as in FIG. 1, it would be preferable to attach or connect the foam to the neck of the vessel prior to seam welding the neck to the cylindrical body. This method should lend itself well to high volume production. Based on analyses and experimental observations, H200 foam represents a very promising exemplary ammonia-storage material. Other materials tested are contemplated for application for storage of ammonia or other liquefied gases (e.g., butane and propane). The embodiments disclosed herein demonstrate the feasibility of the closed-cell foam monolith approach for safe storage of volatile material, particularly safe ammonia storage. Demonstration of feasibility requires showing how this approach can meet, in an aspect, the ammonia release-rate requirements as well as targeted ammonia storage density. The disclosure herein provides exemplary embodiments that demonstrate scalability between the 3-cm cube test samples and larger monolith dimensions. Exemplary ammonia storage systems described in this section demonstrate controlled release of ammonia from closed-cell foam monoliths of utilitarian size. Two exemplary ammonia-storage apparatuses are disclosed, based on DIAB's H200 foam. Rectangular blocks of H200 foam were cut to a cylindrical shape 18 with a diameter of 5 cm (2 in.) and a length of 17 cm (6.7 in.). A 3-mm-dia. hole 20 was bored down the center of each cylinder. Alternative hole sizes and/or multiple channels can be used as necessary, but these devices employed a single channel. FIG. 8 shows an exemplary cylindrical piece along with a section of PVC pipe 15 and PVC end-caps 16, which were used in the all-PVC storage apparatus discussed below. Two volatile storage apparatus designs have been constructed and tested (FIG. 9). Both use identical monoliths of H200 foam (i.e., 5-cm-dia. cylinders, 17-cm long). One embodiment uses a steel pipe 22 and steel end caps 24 to form the “tank” surrounding the foam monolith, and the other, 26, uses a PVC pipe and end caps to form the “tank” (e.g. FIG. 8) The two embodiments also differ in that the monolith in the PVC unit is sealed (by solvent welding a sheet of PVC to the external surface of the monolith) such that ammonia can only enter and exit the monolith via the surface formed by the 3-mm-dia. hole through the center of the monolith. The steel-pipe unit has all surfaces of the monolith exposed. This difference in monolith sealing was implemented to demonstrate how changes in the exposed surface area can be used to control the ammonia release rate. Both embodiments are shown in FIG. 9. Both embodiments were connected directly to a heated (27° C.) tank of liquefied anhydrous ammonia. Ambient temperature remained at about 20-22° C., so liquid ammonia accumulated inside the prototypes under a pressure of 140 psig. The vapor pressure of ammonia is 115 psig at 21° C. and 140 psig at 27° C. Over time, the liquid ammonia diffused into the H200 foam monoliths inside both volatile storage apparatus. The embodiment having the PVC outer “tank” was filled for 68 hours before it was disconnected from the heated ammonia tank. Two identical steel-pipe prototypes were built and tested. One of the steel-pipe embodiments was filled for 48 hours and the other was filled for 68 hours. The mass of each tank was monitored during the filling process. None of the tanks had reached maximum capacity by the time filling was terminated, as was evidenced by fact that the mass of each tank continued to increase. FIG. 10 shows the mass-gain data for the exemplary volatile storage apparatus having the outer “tank.” After 68 hours, the 360 cm3 cylindrical monolith (mass=71 g) had absorbed 25 g of ammonia. This represents an average capacity of 0.07 g NH3/cm3 (26 wt.-% capacity). From the 3-cm-block tests described above, we know the ammonia capacity of this foam is up to 0.50 g NH3/cm3, so the foam monolith in the PVC “tank” embodiment was likely less than one-seventh full when filling was terminated. The steel-pipe prototype filled for 48 hours reached an average storage density of 0.12 g NH3/cm3, and the steel-pipe prototype filled for 68 hours reached 0.15 g NH3/cm3. It should be noted that the foam does not fill uniformly throughout its volume. Instead, the cells nearest the exposed surfaces of the monolith quickly reach capacity, and the cells deeper in the monolith become filled only as ammonia permeates inward from the cells near the surface. Since the monolith fills with ammonia through the same exposed surface area that is involved in the ammonia release, the cells near the surface should be filled to near capacity even if most of the cells deeper in the monolith contain little or no ammonia. Because of this effect, ammonia-release tests using a partially filled monolith are expected to give very similar ammonia release rates to those observed using a fully filled monolith. The release-rate profiles will be similar early in the test, but diverge later with the release rate from the partially filled monolith being lower than that of the (initially) fully filled monolith. It is on this basis that the herein described ammonia release tests using partially filled monoliths are representative of the ammonia release expected from fully filled monoliths. To further illustrate this point, the ammonia release from a monolithic cylinder of a design similar to that used in the PVC “tank” prototype was modeled/simulated. In one case, the simulation assumed the monolith was fully filled to 0.25 g NH3/cm3 before the tank was depressurized. In the other case, the monolith was assumed to be filled such that the one-quarter of the monolith volume nearest the release surface was initially filled to 0.25 g NH3/cm3 and the other three-quarters of the monolith was empty. The simulations are compared in FIG. 11. Significant difference in the predicted release rates is not evident until nearly 7 hours have elapsed All three embodiments were tested using the same procedure used to test the 3-cm cube samples. At time=0, a valve on the tank was opened and the ammonia allowed to escape while the mass of the exemplary tank was monitored. The ammonia release rate data for both steel-pipe embodiments are shown in FIG. 12. Also included are the results of a numerical model simulation for the monolith geometry used for the steel-pipe embodiments. Agreement between the model/simulation and experiment is good. Both prototypes show similar release-rate profiles even though the second unit started with a higher ammonia loading. This is consistent with the argument above and FIG. 11. The steel-pipe embodiments exhibit ammonia release rates on the right order of magnitude (i.e., about 0.1 to 1.0 g/min), and higher or lower release rates can be obtained from alternative monolith geometries. The PVC tank embodiment was built to demonstrate the reduction in ammonia release rate obtained when most of the monolith surface is sealed. In the case of the PVC prototype, only the 3-mm-dia. hole through the axial center of the cylinder was left unsealed. The ammonia release data for the exemplary PVC tank embodiment are provided in FIG. 13. The release rates for the PVC tank embodiment are about a factor of 5 lower than those observed from the steel-pipe embodiments. Based on the numerical modeling for this embodiment, expected release rates to be about a factor of 10 lower. The results of the PVC tank embodiment tests show the ammonia release rate can be controlled not only by adjusting the foam monolith geometry, but also by selectively sealing a fraction of the foam monolith surface area. The PVC tank embodiment also demonstrates a relatively low-weight system for storing volatiles, ammonia particularly, even though no particular effort was made to minimize the mass of the PVC “tank” surrounding the monolith. This embodiment has an ammonia capacity of up to about 180 g. The exemplary embodiment contains 364 cm3 of monolith, which has a mass of 71 g. The PVC pipe/tank and end caps have a combined mass of 340 g. The total mass of this embodiment is 420 g. Thus, the effective storage density is up to 30 wt % (mass of ammonia divided by mass of ammonia plus storage system). Significant increases in this storage density can be made and are contemplated. FIGS. 14 and 15 show additional exemplary volatile compound release rates. FIG. 14 shows the release of propane gas from an aluminum tank filled with R82.110 polyetherimide closed-cell foam from Alcan Baltek Corporation (Northvale, N.J.). The R82.110 foam has a bulk density of 110 kg/m3. Also shown are data for propane release from a titanium tank containing no foam materials. The data show a rapid release of propane from the titanium tank and a slow, controlled release from the tank containing the R82.110 foam. Polyetherimide foam is not chemically compatible with ammonia, but it is compatible with hydrocarbon volatiles such as propane and butane. FIG. 15 shows the slow release of propane from a sample of Alporas® closed-cell aluminum foam from Gleich (Kaltenkirchen, Germany). This foam has a bulk density of about 270 kg/m3 and is made from aluminum metal and is chemically compatible with propane, butane, anhydrous ammonia, and many other volatiles. Safe storage of volatiles, for example ammonia, in closed-cell foam monoliths is a feasible approach based on test results. The present disclosure shows that high storage densities and low ammonia-release rates are achieved, for example, 2.5 g NH3 per gram of monolith (equivalent to 0.50 g NH3/cm3 of monolith). Modeling/simulation implies volatile compound release rates can be conveniently controlled by appropriate selection of monolith geometry and/or sealing a fraction of the monolith surface. Experimental results confirm this. Exemplary costs include 32 liters of DIAB H200 foam for $800. A system storing 500 g of ammonia will require 1 to 2 liters of foam, so foam cost is anticipated to be between $25 and $50 per storage tank. Thus the present disclosure provides for a very cost-effective method and apparatus for safely storing volatile compounds, including but not limited to, ammonia, butane, propane and other compounds. The closed-cell foam monolith approach is attractive because of its simplicity, no heat or power is required to induce release of ammonia to a fuel processor, load following requires no changes to the storage system, and ammonia for example, can be supplied at relatively high pressures (ca. 60 psig) without a significant sacrifice in system safety. The disclosures of each and every publication and reference cited herein are incorporated herein by reference in their entirety. The present disclosure has been explained with reference to specific embodiments. Other embodiments will be apparent to those of ordinary skill in the art in view of the foregoing description. REFERENCES Appleby, A. J., and F. R. Foulkes. 1989. Fuel Cell Handbook Van Nostrand Reinhold, New York. Blomen, L., and M. N. Mugerwa. 1993. Fuel Cell Systems. Plenum Press, New York. Bloomfield, D. P., V. J. Bloomfield, P. D. Grosjean, and J. W. Kelland. 1995. Mobile Electric Power. Analytic Power Corp., NTIS Report ADA296709. Burchell, T. and M. Rogers. 2000. “Low Pressure Storage of Natural Gas for Vehicular Applications.” SAE Technical Paper Series. 2000-01-2205. SAE, Warrendale, Pa. Hiemenz, P C. 1986. Principles of Colloid and Surface Chemistry. 2nd ed. Marcel Dekker, Inc. New York. Nielsen, A. 1995. Ammonia: Catalysis and Manufacture. Springer-Verlag. London. Pilon, L., A. G. Fedorov, and R. Viskanta. 2000. “Gas Diffusion in Closed-Cell Foams.” Journal of Cellular Plastics. 36:451-474 Powell, M R. M S Fountain, C J Call, A S Chellappa. 2002. “Ammonia-Based Hydrogen Generation for Fuel Cell Power Supplies.” Army Science Conference 2002, Orlando, Fla. Dec. 2-5, 2002. Powell, M R. M. Fountain, and C J Call. 2001. “Ammonia-Based Hydrogen Generator for Portable Fuel Cells.” Proceedings international Conference on Microreaction Technologies (IMRET 5). 2001.

<SOH> BACKGROUND <EOH>1. Field of Endeavor The invention relates generally to safe storage of compounds, in particular volatile compounds. In one aspect, the present disclosure relates to the use of foam-cell material to store volatile compounds. In another aspect, the present disclosure provides for the safe storage of a source from which hydrogen may be extracted. 2. Description of Related Art Recent improvements in the design and manufacture of hydrogen/air fuel cells have increased interest in the use of fuel cells as a replacement for batteries and other power supplies (e.g., vehicle engines). Because hydrogen/air fuel cells can operate on very energy-dense fuels and are quiet and efficient, fuel-cell-based power supplies are considered a promising future power source. Many fuel cells operate using hydrogen gas for fuel, and oxygen (typically from air) as an oxidant. Unfortunately, reliable, convenient, and compact hydrogen sources do not yet exist, so fuel cells have yet to receive widespread commercial or military use. Fuel cells, however, represent relatively mature technology and are commercially available. As discussed above, there is a great need and interest in hydrogen generators, including compact hydrogen generators, that extract hydrogen gas from a source. Examples of such sources/volatiles from which hydrogen may be obtained include, but are not limited to, butane, propane and anhydrous ammonia. As can be appreciated, use of hydrogen generators for providing hydrogen gas will likely be restricted unless the sources of hydrogen can be stored in a safe manner. For example, if anhydrous ammonia is the hydrogen source, a method and apparatus for storing ammonia must reduce and/or minimize the potential for a dangerous ammonia release if the integrity of the storage apparatus is compromised. Successful development of a safe ammonia-storage tank is beneficial because it facilitates rapid deployment of ammonia-based hydrogen sources for compact fuel-cell power supplies. Several approaches are available for hydrogen generation and/or storage. These include hydrocarbon and methanol fuel reforming, hydrogen absorption into metal hydrides, hydrogen-generating chemical reactions, and ammonia decomposition (Blomen, L., and M. N. Mugerwa. 1993. Fuel Cell Systems. Plenum Press, New York; Bloomfield, D. P., V. J. Bloomfield, P. D. Grosjean, and J. W. Kelland. 1995. Mobile Electric Power. Analytic Power Corp., NTIS Report ADA296709). Adsorbent-based approaches offer reduced storage pressure, but often at a cost of vastly increased storage volume and mass. Ammonia decomposition and ammonia-based chemical reactions are attractive methods for hydrogen generation because the required chemical reactors tend to be relatively small, simple, and easy to control. Ammonia decomposition has received relatively little attention, however, because of ammonia's toxicity and foul odor, and because it is generally not economical for power production except in remote, low-power applications (Appleby, A. J., and F. R. Foulkes. 1989. Fuel Gel/Handbook Van Nostrand Reinhold, New York). In spite of these drawbacks, hydrogen from ammonia is attractive for at least two reasons: (I) The usable hydrogen per kilogram of fuel is relatively high; and (2) ammonia-based fuel-cell systems can be deployed much sooner than the more complicated hydrocarbon-based fuel reformers. Before ammonia-based hydrogen generators will gain acceptance, the problem of safe ammonia storage must be addressed. Ammonia is a toxic gas that can rapidly damage the eyes and respiratory tract upon exposure to concentrations in the range of about 500-1000 ppm. Exposure to higher concentrations (>5000 ppm) even for short periods can lead to respiratory failure and death (Nielsen, A. 1995. Ammonia: catalysis and Manufacture. Springer-Verlag. London). An ammonia-based hydrogen generator operating in an enclosed environment must not have the potential for rapid ammonia release, as this may be harmful or even deadly for surrounding personnel. The ammonia-based hydrogen generators currently under development (e.g., Powell, M R. M S Fountain, C J Call, A S Chellappa. 2002. “Ammonia-Based Hydrogen Generation for Fuel Cell Power Supplies.” Army Science Conference 2002, Orlando, Fla. Dec. 2-5, 2002) employ lightweight storage tanks made from either aluminum or titanium. These tanks have a mass of approximately 120 g and an ammonia storage volume of about 0.7 liters. The tanks are designed to withstand >1000 psig to ensure they do not burst in response to ammonia vapor pressure, which can exceed 250 psi at temperatures greater than 40° C. However, the storage tanks are not designed to withstand punctures from sharp objects or projectiles such as bullets. Further, there is the possibility for failure of tubing and/or reactor components downstream of the ammonia-storage tank, all of which could result in rapid release of ammonia. Before ammonia-based hydrogen sources can be widely marketed, the ammonia storage tanks must be improved to guard against rapid ammonia release in the event of tank puncture. Currently, safe storage of ammonia (and other selected hazardous liquefied gases) requires use of relatively heavy, thick-walled tanks or loading the ammonia onto high-capacity adsorbents. The storage units in both approaches are heavy and result in undesirable increases in mass of end-use systems such as hydrogen generators for fuel cells. For example, an ammonia-storage system with a 500-gram capacity will have a total mass of about 2000 g or more (capacity<20 wt.-%) if a standard storage tank is used. If an adsorbent is used instead, the mass of adsorbent is expected to be at least three times the mass of ammonia stored, so the resulting storage system will have a mass greater than 2000 g (capacity<20 wt.-%). Monolithic storage structures for gases have received relatively little attention in the literature. This is largely because there is not a perceived need for the ability to store small quantities of toxic or flammable gases under pressure in a small volume. Propane and butane are sold commercially in small quantities as liquids, but safety concerns are mitigated through the use of a heavy storage vessel and warnings regarding indoor storage and use of the fuel. As compact, lightweight fuel-cell power systems become more prevalent, however, greater emphasis is expected on the need to safely store small quantities of these materials for indoor use. Some work along these lines has been performed at the Oak Ridge National Laboratory as part of a program to develop passenger vehicles that can run on natural gas. Storage of the natural gas is the principal obstacle to these vehicles because natural gas cannot be liquefied under ambient temperature conditions. Burchell and Rogers (2000) (Burchell, T. and M. Rogers. 2000. “Low Pressure Storage of Natural Gas for Vehicular Applications.” SAE Technical Paper Series. 2000-01-2205. SAE, Warrendale, Pa.) report on a monolithic storage structure utilizing adsorption of natural gas. Adsorbent fibers are configured into a monolithic block with high adsorption capacity and high thermal conductivity, which are both desirable properties for the vehicle application (high thermal conductivity allows rapid filling of the adsorbent without overheating). In particular, this prior art approach, however, is not likely to be of use for safe ammonia storage. Adsorbent-based approaches suffer from relatively low ammonia storage density and the need to provide heat to desorb the ammonia from the adsorbent. Further, this adsorbent monolith has a high thermal conductivity, which is counter-productive for safe ammonia storage. Low thermal conductivity of the storage matrix is preferred to help retard vaporization of volatiles, for example ammonia, from the monolith. If heat cannot quickly reach the vapor-liquid interface, volatilization of ammonia will be slowed.

<SOH> SUMMARY <EOH>We have examined a variety of methods for improving the safety of storing volatile compounds. One aspect of the disclosure involves storing the volatile compound inside a low-permeability, high-void-fraction, monolithic structure such as a closed-cell foam. In particular embodiments, such foam may be a ceramic foam. In another aspect, the volatile can be at least one of ammonia, butane and propane. This approach offers very high storage density, compact size, and a controlled release rate for the volatile even in the event of tank puncture. Rapid release of the volatile from the foam monolith is controlled by thermal and mass-transfer effects. To escape the monolith, the volatile must permeate through the cell walls to near the surface of the monolith. Experiments described in the disclosure provide evidence that this is a viable concept. Tests demonstrate that closed-cell foam materials offer a promising method for improving the safety of volatile compound storage, particularly for ammonia storage. In an aspect, the present disclosure provides for the safe storage of ammonia utilizing monolithic, closed-cell foam materials, which offer the desired characteristics of compact and lightweight ammonia storage with relatively little safety risk. Lightweight, closed-cell foam materials will be used to fill an ammonia-storage tank and thereby reduce the rate of ammonia release in the event of tank failure. The disclosed closed-cell foam approach results in very little increase in mass and volume over that of the pure liquid ammonia. In addition to storage of ammonia, this approach may have other applications related to the safe storage of other toxic and/or flammable liquefied gases such as butane and propane. Possible alternative applications of such storage configurations will make possible personal heaters for skiing and other cold-weather activities. In accordance with one aspect of the disclosure, a method for storing volatiles under pressure is disclosed that includes providing a storage apparatus where the storage apparatus includes an outer portion and a foam component. The foam component is contained and disposed within an inner space defined by the outer portion. The storage apparatus is then connected to a source, such as a tank, for providing a volatile compound and the volatile is then conducted from the source into the storage apparatus, whereby the voids of the foam component have the volatile compound conducted thereto. In particular aspects, foam component includes closed cells with low, but nonzero, cell-wall permeability. The volatile compound can be at least one of a liquid or gas or combination thereof. Exemplary volatiles can include, but are not limited to, at least one of ammonia, butane and propane or any combination thereof. In particular embodiments, at least a portion of a surface of the foam component is sealed. In accordance with another aspect of the disclosure, an apparatus for storing volatile compounds is disclosed, comprising an outer portion, the outer portion defining an inner volume of the apparatus, and a foam component, where the foam component is disposed and contained within the inner volume defined by said outer portion of the apparatus. The apparatus comprises means for introducing at least one volatile compound into the inner volume containing the foam component. In particular embodiments, the foam component includes closed cells. In some embodiments the outer portion of the apparatus is composed of at least one of a metal, alloy or plastic or any combination thereof. In one aspect, the foam component utilized and disclosed herein has a void fraction of about greater than about 60%. In some embodiments, the apparatus further comprises a sealing component disposed upon at least a portion of the foam component. A flexible elastomer can be utilized as a sealing component, for example. In particular embodiments, the foam component is provided with at least one channel. In another aspect, an apparatus for storing volatile compounds in accordance with the teachings of the present disclosure employs a foam component whose geometry is cylindrical, spherical, or planar. In some embodiments, apparatus can be composed of several disclosed storage apparatus which can be manifolded together to increase volatile delivery rate, wherein a safe delivery rate of each device/apparatus is maintained. In some embodiments, the storage apparatus is arranged in a stacked fashion, thus providing cartridges and is further enclosed in an outer enclosure containing suitable inlet and outlet fittings. In particular embodiments, manifoldable devices allow for charging of volatiles of one or more cartridges or storage apparatus while allowing discharge of a volatile from one or more other cartridges or storage apparatus. In some such embodiments, a provided configuration permits replacement of one or more cartridges or storage apparatus while one or more other cartridges or storage apparatus are delivering volatiles to an end-use system. In particular embodiments, the disclosed apparatus can be air cooled or liquid cooled to improve charging rates. In another aspect, the apparatus and methods disclosed herein can be utilized and provided in accordance with and part of an end-use system. An exemplary end-use system can include a hydrogen generator. Another exemplary end-use system is a fuel cell power system. The teachings of the present disclosure provides for storage of hazardous, liquefied gases in a closed-cell foam material. Release of gas/liquid from the monolith is restricted by the need for the gas to diffuse through the closed cells. Because rapid release is prevented, storage safety is greatly improved. The mechanical strength of the foam monolith provides pressure resistance to the liquefied gas pressure. A tank can be formed by sealing the external surface of the monolith, resulting in a storage system that is very lightweight and safe. Control of the gas release rate can be achieved not only via adjusting foam properties, but also by adjusting the foam monolith geometry. For example, holes can be drilled into the monolith to provide for an increase in surface area that will increase the gas release rate. Alternatively, portions of the monolith surface can be sealed with an impermeable layer thereby decreasing the gas-release rate. The gas release process is approximated by diffusional loss, so geometries expected to increase the rate of gas diffusion out of a monolith (e.g., those with high surface-area-to-volume ratios) will also increase the rate of gas release from the foam-based monolithic gas storage structure. In addition to markets for safe storage of ammonia, niche markets for safe storage of small quantities of other hazardous and flammable liquefied gases are anticipated. Most butane-powered consumer devices are currently not allowed onboard commercial aircraft due to the potential for an in-flight fire. Development of a method to restrict butane release rate in accordance with the teachings of the present disclosure, for example, may result in some of the devices being allowed. Other applications include personal heaters, which are not widely marketed in part because of the risks associated with carrying a pressurized flammable gas in proximity to a flame or catalytic burner. Elimination of the possibility for catastrophic failure of volatile storage apparatus, such as a butane/propane storage tank, would greatly improve the commercial viability of these devices. Further, when hydrocarbon-based fuel reformers become available, safe storage media will be a priority for compact applications designed for indoor use.

20070516

20110607

20080124

65183.0

B65D8500

MAUST, TIMOTHY LEWIS

SAFE STORAGE OF VOLATILES

SMALL

ACCEPTED

B65D

ACCEPTED

Optical component for introducing optical aberrations to a light beam

An optical component (48) for introducing optical aberrations to a light beam defining an optical axis (28) is described, comprising a fluid chamber (46) having a first fluid (56) and at least a second fluid (58) therein, the first and second fluid (56, 58) being nonmiscible, the first fluid (56) and the second fluid (58) being in contact along an interface (60) extending through the fluid chamber (46) substantially transverse to the optical axis (28), the first and second fluids (56, 58) having different indices of refraction, the first fluid (56) being substantially electrically insulating and the second fluid (58) being substantially electrically conductive; at least a first electrode (62-70) separated from the second fluid (58) and at least a second electrode (72) acting on the second fluid to alter the shape of the interface (60) in dependence on a voltage applied between the first and second electrode (62-70, 72). The at least one first electrode (62-70) is arranged in an intermediate portion with respect to the interface (60) such that the intermediate portion (A, B) of the interface (60) is moved substantially in direction of the optical axis (28) in dependence on the voltage applied between the at least one first electrode (62-70) and the at least one second electrode (72)

1. An optical component for introducing optical aberrations to a light beam (20′, 22″) defining an optical axis (28), comprising: a fluid chamber (46) having a first fluid (56) and at least a second fluid (58) therein, the first and second fluids (56, 58) being non-miscible, the first fluid (56) and the second fluid (58) being in contact along an interface (60) extending through the fluid chamber (46) substantially transverse to the optical axis (28), the first and second fluids (56, 58) having different indices of refraction, the first fluid (56) being substantially electrically insulating and the second fluid (58) being substantially electrically conductive; at least a first electrode (62-70; 74-78) separated from the second fluid (58) and at least a second electrode (72) acting on the second fluid to alter the shape of the interface (60) in dependence on a voltage applied between the first and second electrode (62-70, 72); characterized in that the at least one first electrode is arranged in an intermediate portion with respect to the interface (60) such that the intermediate portion (A, B) of the interface (60) is moved substantially in direction of the optical axis (28) in dependence on the voltage applied between the at least one first electrode (62-70; 74-78) and the at least one second electrode (72). 2. The optical component of claim 1, characterized in that the at least one first electrode (62-70; 74-78) is arranged in a wall (52) of the fluid chamber (46) transverse to the optical axis (28). 3. The optical component of claim 1, characterized in that the at least one first electrode (62-70; 74-78) is configured as a thin plate having its plane arranged perpendicular to the optical axis (28). 4. The optical component of claim 1, characterized in that a plurality of first electrodes (62-70; 74-78) electrically insulated from one another are arranged side by side in substantially one plane perpendicular to the optical axis (28). 5. The optical component of claim 4, characterized in that the first electrodes (62-70; 74-78) are separately connected to a voltage supply such that different voltages can be applied between the at least one second electrode (72) and one of the first electrodes (62-70; 74-78). 6. The optical component of claim 4, characterized in that the first electrodes (62-70; 74-78) differ from one another in size and/or shape. 7. The optical component of claim 1, characterized in that the at least one electrode (62-70) is configured in ring shape. 8. The optical component of claim 4, characterized in that the first electrodes (62-70) are configured as rings arranged concentrical with respect to the optical axis (28). 9. The optical component of claim 4, characterized in that the plurality of first electrodes (74-78) comprises at least three first electrodes (74-78), two first electrodes (76, 78) of which are configured in elliptical or oval shape, which are arranged parallel to and in a distance from one another, and which are encompassed by a third first electrode (74) which fills the remaining portion between the two first electrodes (76, 78). 10. A scanning device for optical record carriers, characterized by an optical component (48) of claim 1.

The invention relates to an optical component for introducing optical aberrations to a light beam defining an optical axis, comprising a fluid chamber having a first fluid and at least a second fluid therein, the first and second fluids being non-miscible, the first fluid and the second fluid being in contact along an interface extending through the fluid chamber substantially transverse to the optical axis, the first and second fluids having different indices of refraction, the first fluid being substantially electrically insulating and the second fluid being substantially electrically conductive; at least a first electrode separated from the second fluid and at least a second electrode acting on the second fluid to alter the shape of the interface in dependence on a voltage applied between the first and second electrode. Such an optical component is known from document WO 03/069380 A1. An optical component mentioned at the outset is, for example, used in a scanning device for optical record carriers. Record carriers can be, for example, compact-disks (CD) or digital versatile disks (DVD). In a scanning device for optical record carriers, a light beam, which is generated by a light source, for example a semi-conductor laser, is directed through an objective lens and focused onto the information layer of the record carrier through a transparent protection layer of the record carrier. The transparent protection layer through which the light beam must pass causes an optical aberration, in particular a spherical aberration in the light beam which deteriorates the quality of the focus of the light beam on the information layer of the record carrier. Another optical aberration caused by the transparent protection layer is a coma aberration, which is predominantly caused by a tilt of the record carrier with respect to the optical axis of the light beam or by a centering error of the record carrier. Such optical aberrations have a negative influence on the output signals of the scanning device. Therefore, there is a need to compensate for optical aberrations in such scanning devices. While spherical aberration can be compensated by a specific lens design of the objective lens, it is also possible and in some instances preferred if separate from the objective lens an additional optical component is arranged in the light beam path for compensating for the optical aberrations. In particular, since the optical aberrations can vary from one record carrier to another record carrier due to different thicknesses of the transparent protection layer or due to different tilts or centering errors of the record carriers with respect to the light beam, it is desired to have a variable compensation for such optical aberrations in order to be able to respond to variable or different kinds and/or different degrees or amounts of optical aberrations. Document WO 03/069380 A1 mentioned above discloses a variable focus lens, which can introduce an optical aberration to the light beam in order to compensate for an optical aberration caused by, for example, the record carrier to be scanned. This variable focus lens comprises a first fluid and a second, non-miscible, fluid, which are in contact over a meniscus as the interface. A first electrode separated from the fluid bodies by a fluid contact layer and a second electrode in contact with the first fluid is provided to cause an electro-wetting effect whereby the shape of the meniscus can be altered by applying a voltage between the electrodes. The fluid contact layer has a substantially cylindrical inner wall. The first electrode of this known variable focus lens is a substantially cylindrical electrode encompassing the circumferential wall of the fluid chamber parallel to the optical axis. The second electrode is configured as a ring with a central aperture, which is, arranged perpendicular to the optical axis. This known variable focus lens relies on the effect that the wettability of a fluid on a wall can be altered by applying an electric field to the fluids in the fluid chamber. In this known arrangement, the refractive interface between the first and second fluids can be made aspherical, thus providing for a spherical aberration correction. However, this known variable focus lens has the following drawback. Since the known variable focus lens relies on the electro-wetting effect, the electrodes influence the angle of the meniscus at the circumferential wall, but there is only a limited influence on the central meniscus shape so that only a limited number of different aspherical surfaces can be obtained in the refractive interface between the two fluids, thereby limiting the ability of compensating for a large number of different kinds and degrees of optical aberrations in the light beam. Other optical components which are capable of producing wave front aberrations are based on liquid crystal cells, which, for example, are disclosed in document US 2003/0007445 A1 or in US 2002/0181367 A1. Such liquid crystal cells have, however, the drawback to be expensive to make because of a plurality of alignment layers involved, making these liquid crystal cells not a cost-effective solution for introducing and thus compensating for optical aberrations in a light beam. Furthermore, the switching time of these liquid crystal cells is of the order of a few milliseconds, which does not allow fast switching or tuning. Therefore, it is an object of the present invention to improve an optical component as mentioned at the outset in order to achieve more freedom in surface shape while allowing fast switching speeds and incurring only low manufacturing costs. This object is achieved with respect to the optical component mentioned at the outset in that the at least one first electrode is arranged in an intermediate portion with respect to the interface such that the intermediate portion of the interface between the circumferential wall is moved substantially in direction of the optical axis in dependence on said voltage applied between the at least one first electrode and the at least one second electrode. The concept of the optical component according to the invention is based on the insight that it is possible to pull a contacting liquid, i.e. the second fluid towards electrodes that are placed underneath the electrically insulating fluid layer, i.e. the first fluid. In the known electro-wetting devices, the shape of the interface is deformed by influencing the contact angle of the meniscus with the wall. In between the walls the interface cannot be influenced and takes the shape that belongs to a state of a minimum in surface free energy. In contrast, by virtue of the optical component according to the invention, the second, electrically conductive fluid is influenced by the at least one first electrode which is arranged such that the electric field generated between the first and second electrodes acts through the interface onto the second electrically conductive fluid in an intermediate portion between the circumferential wall of the fluid chamber and substantially perpendicular to the interface, and by applying a respective voltage between the at least one first electrode and the second electrode, the interface between the first and second fluid is moved substantially in direction of the optical axis towards the at least one first electrode or away from same. Thus, it is possible to influence the curvature of the interface or meniscus even in between the circumferential wall of the fluid chamber. In other words, the electrical field generated by the at least one first electrode and the at least one second electrode acts substantially perpendicular through the interface onto the second, electrically conductive fluid, thereby moving same substantially parallel to the optical axis. The at least one first electrode is preferably arranged in a wall of the fluid chamber transverse to the optical axis, which represents a light entrance or light exit wall of the optical component. Thus, the at least one first electrode is arranged in the optical path of the light beam, but this does not result in a technical problem, because the at least one first electrode can be made of a transparent material, for example indium tin oxide which is a material already in use for making transparent electrodes. In a preferred refinement of the invention, the at least one first electrode is configured as a thin plate having its plane arranged perpendicular to the optical axis. Further, it is preferred, if a plurality of first electrodes electrically insulated from one another are arranged side by side in substantially one plane perpendicular to the optical axis. Thus, it is possible to adjust an interface shape having simultaneously concave and convex portions, for example. In this connection, it is preferred, if the first electrodes are separately connected to a voltage supply such that different voltages can be applied between the at least one second electrode and one of the first electrodes. Thus, it is possible to control each of the first electrodes separately from one another so that the number of possible interface or meniscus shapes is still enhanced. Preferably, the several first electrodes can differ from another in size and/or shape, wherein, for example, the sizes and/or shapes of the single first electrodes can be chosen in dependence on the specific optical aberration to be introduced to the light beam. Thus, it is also possible to provide for optical aberration compensation in a non-rotational symmetric fashion with respect to the optical axis. Further, it can be preferred, if the at least one electrode is configured in ring shape, and if a plurality of first electrodes are configured as rings arranged concentrically with respect to the optical axis, when it is desired to provide for aberration correction in a rotational symmetric fashion with respect to the optical axis. By supplying the different rings arranged around the optical axis with different voltages, the desired shape of the refractive interface between the two fluids can be adjusted. In another preferred refinement, the plurality of first electrodes comprises at least three first electrodes, two first electrodes of which are configured in elliptical or oval shape which are arranged parallel and in a distance from one another and which are encompassed by a third first electrode which fills the remaining portion between the circumferential wall. Such configuration of the first electrodes is in particular suited for introducing a coma aberration to the light beam for compensating for coma aberrations. The invention further relates to a scanning device for optical record carriers, which comprises an optical component of anyone of the afore-mentioned configurations. Further features and advantages will be apparent from the following description and the accompanying drawings. It is to be understood that the features mentioned above or to be described below are not only applicable in the combinations given, but also in other combinations or isolation without departing from the scope of the invention. Preferred embodiments of the invention are described in the following with respect to the accompanying drawings. In the drawings: FIG. 1 shows a scanning device for record carriers in a schematic illustration, which comprises an optical component for introducing optical aberrations to a light beam; FIG. 2 is a cross-sectional enlarged side view of a first embodiment of an optical component for introducing optical aberrations to a light beam in a rest state; FIG. 3 shows the optical component in FIG. 2 in a second exemplary operating state for introducing optical aberrations; FIG. 4 is a view of the optical component in FIGS. 2 and 3 in a cross-section along line IV-IV in FIG. 2; FIG. 5 is a view of another embodiment of an optical component for introducing optical aberrations to a light beam in a cross-section along line V-V in FIG. 6; and FIG. 6 is a cross-sectional view of the optical component in FIG. 5 in an exemplary operating state. FIG. 1 shows a scanning device 10 for scanning an optical record carrier 12. The record carrier comprises a transparent layer 14, on one side of which an information layer 16 is arranged. The side of the information layer 16 facing away from the transparent layer 14 is protected from environmental influences by a protection layer (not shown). The transparent layer 14 acts as a substrate for the record carrier 12 by providing mechanical support for the information layer 16. The record carrier 12 is, for example, a compact-disk (CD) or a digital versatile disk (DVD). Information may be stored in the record carrier 12 in the form of optically detectable marks arranged in substantially parallel, concentric or spiral tracks in the information layer 16 (not shown). The marks may be in any optically readable form, for example in the form of pits, areas with a reflection coefficient or a direction of magnetization different from their surroundings, or a combination of these forms. The scanning device 10 comprises a light source 18, for example a semi-conductor laser, which emits a diverging light beam 20. A beam splitter 22, for example a semi-transparent plate, reflects the light beam 20 towards a collimator lens 24 forming a collimated beam 20′, which is incident on an objective lens 26. The objective lens 26 transforms the light beam 20′ to a converging beam 20″, which passes through the transparent layer 14 and impinges on the information layer 16 of the record carrier 12. While in the embodiment shown the collimator lens 24 and the objective lens 26 are shown as separate optical elements, they also can be combined in a single lens. The collimator lens 24 and the objective lens 26 define an optical axis 28 of the light beam 20′, 20″. The light beam 20″ is reflected by the information layer 16 and returns on the same path of the light beam 20″ to the beam splitter 22 where at least a part of the reflected light beam is transmitted towards a detection system 30. The detection system 30 captures the light and converts it into one or more electrical signals. One of these signals is an information signal 32, the value of which represents the information read from the information layer 16. Another signal is a focus error signal 34, the value of which represents the axial difference in height between the focus F on the information layer 16 and the information layer 16. The focus error signal 34 is used as an input for a focus servo controller 36, which controls the axial position of the objective lens 26, thereby controlling the axial position of the focus F such that focus F substantially coincides with the plane of the information layer 16. Further, a center servo controller can be provided to laterally displace the objective lens 26 in order to respond to a centering error of the record carrier 12. Further, an optical component 40 for introducing optical aberrations into the light beam 20′, 20″ is arranged in the path of the light beam 20′, 20″. In the present embodiment, the optical component 40 is arranged between the collimator lens 24 and the objective lens 26. The optical component 40 can, however, also be positioned behind the objective lens 26 seen in the direction of the light beam 20′, 20″, i.e. between the objective lens 26 and the optical record carrier 12. The optical component 40 introduces optical aberrations like spherical aberration and/or coma aberration into the light beam 20′, 20″, in order to compensate for corresponding aberrations caused by the transparent layer 14, in particular in case of a tilt error or a centering error of the optical record carrier 12. The optical component 40 has tunable aberration characteristics, which are controlled by a control system 42 connected to the optical component 40 via one or more electrical lines 44. With respect to FIGS. 2 through 4, a first embodiment of the optical component 40 will be described hereinafter. The optical component 40 comprises a fluid chamber 46 defining an optical axis, which is the optical axis 28 in FIG. 1. The fluid chamber 46 is housed by a tightly sealed container 48 having a circumferential wall 50, which is substantially cylindrical in shape. However, other shapes can be envisaged for the circumferential wall 50. The container 48 further comprises a bottom wall 52 and a top wall 54 which are transverse, in the present embodiment perpendicular with respect to the optical axis 28. In case that the circumferential wall 50 is cylindrical, the bottom wall 52 and the top wall 54 are circular in shape. The expressions “bottom wall” and “top wall” can also be used in inversed manner, i.e. the wall 52 can also be the “top wall” while the wall 54 then is the “bottom wall”. At least the bottom wall 52 and the top wall 54 are transparent so that the light beam 20′ or the light beam 20″ in FIG. 1 can pass through the bottom wall 52 and the top wall 54 of the container 48. The circumferential wall 50 can also be made of a transparent material, which, however, is not necessary, because the circumferential wall 50 is not used as entrance or exit face for the light beams 20′, 20″. The fluid chamber 46 is filled with a first fluid 56 and a second fluid 58. The first fluid 56 and the second fluid 58 are non-miscible with respect to one another. Further, the first fluid is substantially electrically insulating and the second fluid 58 is substantially electrically conductive. The first fluid 56 and the second fluid 58 are in contact with one another along an interface 60 extending through the fluid chamber 46 substantially transverse to the optical axis 28. The first fluid 56 may be a silicone oil or an alcane, referred to herein simply as “oil”, while the second fluid 58 is water containing a salt solution, for example. The two fluids 56 and 58 are preferably arranged to have an equal density, so that the optical component 40 functions independently of orientation, i.e. without dependence on gravitational effects between the two fluids 56 and 58. This may be achieved by appropriate selection of the first fluid constituent. To this end, alcanes or silicone oils may be modified by addition of molecular constituents to increase the density to match that of the salt solution, for example. The indices of refraction of the first fluid 56 and the second fluid 58 differ from another so that the interface 60 represents a refracting surface. Further, the thickness of the first fluid 56 may be in the range of about 10 μm to about 200 μm or several hundreds of μm. The optical component 40 further comprises at least one first electrode, in the embodiment shown a plurality of first electrodes 62, 64, 66, 68, 70. The first electrodes 62-70 are configured as rings, which are arranged concentrically with respect to the optical axis 28. The first electrodes 62-70 are made of an electrically conductive transparent material like indium tin oxide. The first electrodes 62-70 are embedded in the bottom wall 52 of the container 48, and, thus, are not in contact with the first fluid 56 or the second fluid 58. In other embodiments, the electrodes 62-70 can be deposited on the inner surface of wall 52 and separated from the first fluid by a separation layer like polyethertetrafluorethylene. At least one second electrode, in the present embodiment one second electrode 72 is in contact with the second electrically conductive fluid 58. The second electrode 72 is, for example, immersed in the second fluid 58. Each of the first electrodes 62-70 is connected to a voltage supply such that a voltage V1 can be applied to electrode 62, a voltage V2 to electrode 64, a voltage V3 to electrode 66, a voltage V4 to electrode 68 and a voltage V5 to electrode 70, where V1-V5 differ from one another, but the voltages V1-V5 can also be the same for two or more of the electrodes 62-70. The electrodes 62-70 are configured as thin plates having their plane arranged perpendicular to the optical axis 28, as shown in FIGS. 2 and 3. The electrodes 62-70 are, further, arranged side by side in substantially one plane perpendicular to the optical axis 28 between the circumferential wall 50. The single first electrodes 62-70 are controlled by the control system 42 in FIG. 1 via the line or lines 44, accordingly. FIG. 2 shows the rest state of the optical component 40, when the voltages V1-V5 are zero or have all the same value. In this case the interface 60 between the first fluid 56 and the second fluid 58 is substantially plan or even. Starting from the operating state shown in FIG. 2 and, for example, applying a voltage V5 which is not zero to the first electrode 70, an electric field is generated which is directed through the first electrically insulating fluid 56 through the interface 60 and acts on the electrically conductive second fluid 58 substantially perpendicular to the interface 60 thereby pulling the second fluid 58 to the first electrode 70 or pushing it away depending on the sign of the voltage V5 in that portion A. The magnitude of the voltage V5 determines the stroke by which the second fluid 58 is pushed away from or pulled towards the first electrode 70. Further, if, for example, a voltage V2 is applied to the first electrode 64, the second fluid 58 is also pushed away from or pulled towards the first electrode 64 according to the sign of the voltage V2 in the portion B of the interface 60 next to the electrode 64. Thus, by applying respective voltages V1, V2, V3, V4, V5 to the electrode 62, 64, 66, 68, 70, an arbitrary shape of the refracting interface 60 can be obtained, and, thereby, the desired shape of the interface 60 suitable for introducing the desired optical aberration into the light beam 20′ or 20″ can be adjusted. The pushing or pulling effect is rendered possible by the fact that the first electrodes 62-70 are arranged in an intermediate portion of the fluid chamber 46 between the circumferential wall 50. FIG. 3 shows an arbitrary shape of the interface 60, which has been adjusted by an appropriate choice of the voltages V1-V5. In the embodiment shown in FIGS. 2 through 4, any shape of the interface 60 which is formed by corresponding voltages V1-V5 is rotational symmetric with respect to the optical axis 28, because the electrodes 62-70 are configured as rings which are arranged concentrically with respect to the optical axis 28. However, it could be envisaged to provide other numbers, shapes and/or sizes of first electrodes in order to be able to adjust any desired shape of the interface 60, which also includes rotationally asymmetric shapes with respect to the optical axis 28. For example, in order to increase the number of electrodes in the embodiment of FIGS. 2 through 4, the electrodes 62-70 could be designed as half rings by interrupting the rings of the electrodes 62-70 along a straight line, thus increasing the number of electrodes from five to ten. In this case, the ten resulting electrodes can have a voltage supply of their own, thus having the opportunity to apply ten different voltages to the ten electrodes, by which a rotational asymmetric shape of the interface 60 can be achieved. Another embodiment of the optical component 48′ is shown in FIGS. 5 and 6, which differs from the optical component 48 in FIGS. 2 through 4 only by the configuration of the first electrodes so that the optical component 48′ is only described with respect to the first electrodes. Elements shown in FIGS. 5 and 6 which are equal or similar elements shown in FIGS. 2-4 are referenced by the same numerals supplemented with a prime. The optical component 48′ comprises three first electrodes 74, 76, 78. The first electrodes 76 and 78 are configured substantially in oval or elliptical shape, which are arranged parallel and which are spaced from one another. The first electrode 74 encompasses the first electrodes 76 and 78 and is electrically insulated from the electrodes 76 and 78. The electrode 74 fills the remaining space in the bottom wall 52′. When applying a voltage V0=0 to the electrode 74, a voltage V1=V to the electrode 78, and a voltage V2=−V to the electrode 76, the interface 60′ takes the shape as shown in FIG. 6, thus, when the light beam 20′ passes through the optical component 48′, introducing a cometic wave front into the light beam 20′. Other embodiments and modifications of the embodiments described above will be apparent to those skilled in the art, in particular other numbers, shapes and/or sizes of the first electrodes can be used in dependence on the optical aberrations to be introduced into the light beam for compensating for the corresponding optical aberrations in the scanning device 10.

20060822

20090127

20070621

63011.0

G02B2608

CHOI, WILLIAM C

OPTICAL COMPONENT FOR INTRODUCING OPTICAL ABERRATIONS TO A LIGHT BEAM

UNDISCOUNTED

ACCEPTED

G02B

ACCEPTED

Sealing device for a radial swivel motor

Swivel motors have a large number of tightness problems on the inside, in particular in a broad operating temperature range. Therefore, to improve the tightness over a temperature range of −40° C. to +130° C., a sealing device (20) is provided with an inner soft sealing element (20) and a plurality of outer rigid sealing elements (21, 22, 23, 24). The soft sealing element (20) and the rigid sealing elements (21, 22, 23, 24) are undetachably connected to one another. The circumferential sealing surfaces of the rigid sealing elements (21, 22, 23, 24), in the unloaded state, close flush with the sealing surface of the soft sealing element (20). The rigid sealing elements (21, 22, 23, 24) are spaced apart from one another by at least one radial compensating groove (25) and at least one axis-parallel compensating groove (26). The compensating grooves (25, 26) are arranged on both sides of the sealing device, such that the compensating grooves (25, 26) on one side are not overlapped by the compensating grooves (25, 26) on the other side.

1. A sealing device for a radial swivel motor including a stator with at least one stator wing and a rotor with at least one rotor wing, which form at least one sealing chamber and one inlet chamber, the sealing device for sealing in the inward direction, whereby the sealing device is pressed into a mounting groove (18) of said rotor wing and of said stator wing, the sealing device comprising: outer rigid sealing elements; and a pretension element made of an elastomer connecting said outer rigid sealing elements to one another, said pretension element comprising a soft sealing element and said outer rigid sealing elements providing a multipart construction, whereby said soft sealing element and said rigid sealing elements are connected undetachably to one another, circumferential sealing surfaces of said rigid sealing elements, in the unloaded state, end flush with the sealing surface of said soft sealing element, said rigid sealing elements are spaced apart from one another by at least one radial compensating groove and at least one said axis-parallel compensating groove, and said compensating grooves are arranged on both sides of said sealing device, such that said compensating grooves on one side are not overlapped by said compensating grooves on the other side. 2. A sealing device in accordance with claim 1, wherein said soft sealing element and said rigid sealing elements are dimensioned in length and depth and coordinated to one another such that they remain in said widely reduced compensating grooves even after the assembly of said sealing device. 3. A sealing device in accordance with claim 1, wherein said soft sealing element consists of such an elastomer and has such dimensions that the pretension resulting therefrom is greater than the contraction of said soft sealing element and said rigid sealing elements resulting from a reduction in temperature. 4. A sealing device in accordance with claim 1, wherein said radial compensating groove and said axis-parallel compensating groove are designed as compressed-oil-carrying channels and are connected to the respective sealing chamber of the swivel motor. 5. A sealing device in accordance with claim 1, wherein said soft sealing element and said rigid sealing elements are connected to one another by bonding or by vulcanization. 6. A radial swivel motor sealing device comprising: outer rigid sealing elements; and a pretension element made of an elastomer connecting said outer rigid sealing elements to one another, said pretension element comprising a soft sealing element and said outer rigid sealing elements cooperating with said soft sealing element to provide a multipart construction, wherein: said soft sealing element and said rigid sealing elements are connected undetachably to one another; circumferential sealing surfaces of said rigid sealing elements, in an unloaded state terminate flush with the sealing surface of said soft sealing element; said rigid sealing elements are spaced apart from one another by at least one radial compensating gap and at least one said axis-parallel compensating gap; and said compensating gaps are arranged on both sides of said sealing device, such that said compensating gaps on one side are not overlapped by said compensating gaps on the other side. 7. A radial swivel motor sealing device in accordance with claim 6, wherein said soft sealing element and said rigid sealing elements are dimensioned in length and depth and coordinated to one another in said multipart construction to provide reduced compensating gaps after the assembly of said sealing device. 8. A radial swivel motor sealing device in accordance with claim 6, wherein said soft sealing element consists of such an elastomer and has such dimensions that the pretension resulting therefrom is greater than a contraction of said soft sealing element and said rigid sealing elements resulting from a reduction in temperature. 9. A radial swivel motor sealing device in accordance with claim 6, wherein said radial compensating gap and said axis-parallel compensating gap form compressed-oil-carrying channels and are connected to the respective sealing chamber of the swivel motor. 10. A radial swivel motor sealing device in accordance with claim 6, wherein said soft sealing element and said rigid sealing elements are connected to one another by bonding or by vulcanization. 11. A radial swivel motor comprising: a stator; a rotor with a rotor wing; a sealing device comprising a pretension element made of an elastomer comprising a soft sealing element and said outer rigid sealing elements connected to said soft sealing element, wherein said soft sealing element and said rigid sealing elements are connected undetachably to one another, circumferential sealing surfaces of said rigid sealing elements, in an unloaded state terminate flush with the sealing surface of said soft sealing element, said rigid sealing elements are spaced apart from one another by at least one radial compensating gap and at least one said axis-parallel compensating gap, and said compensating gaps are arranged on both sides of said sealing device, such that said compensating gaps on one side are not overlapped by said compensating gaps on the other side, said sealing device being pressed into a mounting groove of said rotor wing for sealing at least one sealing chamber and one inlet chamber. 12. A radial swivel motor in accordance with claim 11, wherein said soft sealing element and said rigid sealing elements are dimensioned in length and depth and coordinated to one another to provide reduced compensating gaps after the assembly of said sealing device. 13. A radial swivel motor in accordance with claim 1 1, wherein said soft sealing element consists of such an elastomer and has such dimensions that the pretension resulting therefrom is greater than a contraction of said soft sealing element and said rigid sealing elements resulting from a reduction in temperature. 14. A radial swivel motor in accordance with claim 11, wherein said radial compensating gap and said axis-parallel compensating gap form compressed-oil-carrying channels and are connected to the respective sealing chamber of the swivel motor. 15. A radial swivel motor sealing device in accordance with claim 1 1, wherein said soft sealing element and said rigid sealing elements are connected to one another by bonding or by vulcanization.

CROSS REFERENCE TO RELATED APPLICATIONS This application is a United States National Phase application of International Application PCT/DE2005/000349 and claims the benefit of priority under 35 U.S.C. §119 of German Application DE 10 2004 010 432.8 filed Mar, 1, 2004, the entire contents of which are incorporated herein by reference. FIELD OF THE INVENTION The present invention pertains to a sealing device for a radial swivel motor. Swivel motors of this type are particularly used in automobile construction as well as in aeronautics and space travel. BACKGROUND OF THE INVENTION A radial swivel motor usually consists of a housing, which has at least one stator wing in the interior and is closed on the faces with covers, and of a rotor, which is composed of a driven shaft mounted in the covers and at least one rotor wing. The rotor wing is pivotable against the stator wing of the housing only to a limited extent and thus forms, with the stator wing, at least one pressure chamber and one inlet chamber. To guarantee the inner tightness between the pressure chamber and the inlet chamber, both the rotor wing and the stator wing are equipped with a form-fitting sliding sealing element, which rests against the lateral covers and against the inner wall of the housing or against the rotor. Again and again, a great number of tightness problems occur right in this area because the sealing elements are subject to increased wear. This is due to the limited rotary motion of the rotor, which changes again and again, and because the sealing elements are also exposed to a very broad operating temperature range. A few suggestions have already become known for solving these problems. Thus, DE 199 35 234 C1 describes an embodiment of the sliding sealing element, which consists of a filler piece that carries a circular sealing body under pretension, whereby the filler piece is embodied as divided and thus longitudinally mobile parallel to one another, and at least one spring element is arranged between the filler pieces. Thus, the filler pieces are twisted by forces each acting in opposition to one another. The drawback of this sealing variant is that the sealing strip consists of a large number of component parts and thus it is expensive to manufacture and complicated to mount. Moreover, the spring elements consisting of a soft material have only a low volume, so that the pretension forces produced are therefore also very low. What's more, the spring elements only act in the radial direction. All of this leads to leakage. Supporting the action of an elastic pretension element with one or more metal springs integrated in the pretension element is now known from DE 199 27 619 A1, whereby the metal spring may be a diaphragm spring, corrugated spring, coil spring or compression spring. The pretension forces for the sealing elements are increased by means of the additional metal springs; however, this solution can hardly be technically embodied for this purpose. The compression springs must act, namely, in the radial and axis-parallel directions in relation to the axis of rotation and thus the compression springs must also be arranged in an intersecting manner. This requires a very wide mounting space in the axial direction, which is simply not present because of the dimensions of the rotor wing or of the stator wing. On the other hand, DE 199 27 621 A1 discloses a strip-like sliding sealing element that consists of a first square sealing frame made of PTFE, a second square sealing frame made of PTFE and a pretension element made of an elastomer. Both sealing frames and the pretension element are designed as being of the same size and are joined together in a sandwich-like manner into a pack by bonding or by vulcanization, and both sealing frames are arranged offset to one another both in the radial and axial directions. The pretension element is arranged between the two sealing frames and, with corresponding lateral projections, engages in the cavities of the two sealing frames, so that the two sealing frames, when installed in the swivel motor, are pretensioned in opposition by the forces of the pretension element equally in the radial and axial directions. All of the solutions mentioned have in common the fact that the actual sealing element consists of a hard plastic PTFE and is loaded by a corresponding spring element to reduce the sealing gap. This spring element is usually an elastomer material. Sealing elements made of PTFE have good sliding properties, as a result of which they are actually readily suitable for sealing components sliding on one another. However, an open sealing gap, through which compressed oil can overflow, always remains for manufacturing reasons. The size of the sealing gap is, however, also dependent on the operating temperature of the swivel motor. Thus, the sealing gap expands as the temperature becomes lower, while with a higher temperature the contact pressure of the sealing elements at the housing parts increases. With an expanding sealing gap, the waste oil stream increases, and with a higher contact pressure, the wear of the sealing elements increases. Both are unwanted. All the sliding sealing elements mentioned are thus unsuitable for the required temperature range of −40° C. to 130° C. SUMMARY OF THE INVENTION Therefore, the basic object of the present invention is to develop a sealing device, whose sealing gaps between the pressure chamber and the inlet chamber of the swivel motor are independent of the temperature. According to the invention, a sealing device or arrangement for a radial swivel motor is provided. The swivel motor includes a stator with at least one stator wing and a rotor with at least one rotor wing, which form at least one sealing chamber and one inlet chamber and which are equipped with a sealing device each for sealing in the inward direction. Each sealing device is pressed into a mounting groove of the rotor wing and a mounting groove of the stator wing. Each sealing device includes outer rigid sealing elements and a pretension element made of an elastomer connecting the outer rigid sealing elements to one another. The sealing device includes a pretension element designed as a soft sealing element. The outer rigid sealing elements have a multipart design, whereby the soft sealing element and the rigid sealing elements are connected undetachably to one another. The circumferential sealing surfaces of the rigid sealing elements, in the unloaded state, close flush with the sealing surface of the soft sealing element. The rigid sealing elements are spaced apart from one another by at least one radial compensating groove and at least one axis-parallel compensating groove. The compensating grooves are arranged on both sides of the sealing device, such that the compensating grooves on one side are not overlapped by the compensating grooves on the other side. The novel sealing device eliminates the above-mentioned drawbacks of the state of the art. Thus, the novel sealing device is primarily characterized by a very good sealing function. This can be mainly attributed to the novel combination of various types of sealing elements. Thus, the novel sealing device breaks with the bias that soft packings are unsuitable for relative motions directed at an angle to the sealing element, as they occur precisely in swivel motors. This is achieved by the rigid sealing elements on both sides of the soft sealing element, which, on the one hand, take charge of a support function for the soft sealing element and which, at the same time, smooth the housing parts, such that the soft sealing element continues to be protected from the unevennesses of the metallic housing parts. The high sealing function can also be attributed to the fact that, now with the two outer rigid sealing elements and the soft inner sealing element, three sealing parts are involved in the sealing function. However, the particular advantage lies in the fact that the sealing device maintains its high sealing function even over a broad temperature range. Thus, the sealing function is largely independent of the temperature. This is achieved because the rigid sealing elements have a multipart design and are each loaded so strongly by the pretension (also referred to as compression) through the soft sealing element and by the hydraulic pressures prevailing in the compensating gaps that each volume contraction is compensated. This contraction is compensated in each direction, i.e., not only in the radial and axis-parallel directions, but also in the diagonal direction. Thus, a constantly high tightness on the entire circumference, i.e., also in the corners of the sealing device is guaranteed. It is particularly advantageous when all the soft and rigid sealing elements are so dimensioned that sufficiently wide compensating gaps arise, so that, after the assembly which is carried out at room temperature, a sufficient gap remains for the contraction compensation. Thus, the sealing function can continue to be maintained even at correspondingly low temperatures. It is also advantageous when the soft sealing element is designed such that the pretension to be achieved can be selected to be greater than the expected contraction of all the components involved in the sealing. This also makes use at low temperatures possible. Furthermore, it is advantageous if the compensating gaps are designed as compressed-oil-carrying channels and are connected to the respective sealing chamber of the swivel motor. Thus, the rigid sealing elements can be loaded with a hydraulic pressure, whose forces support the pretension forces. This increases the tightness over the entire temperature range. It is also advantageous if the soft sealing element and the rigid sealing elements are undetachably connected to one another by bonding or by vulcanization. As a result of this, the entire sealing device becomes one component, which greatly reduces the assembly effort of the swivel motor. The present invention shall be explained in detail based on exemplary embodiments. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated. BRIEF DESCRIPTION OF THE DRAWINGS In the drawings: FIG. 1 is the longitudinal sectional view of a swivel motor and sealing device according to the invention; FIG. 2 is a perspective view of the rotor of the swivel motor of FIG. 1; and FIG. 3 is a perspective view of the sealing device in the unloaded state. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings in particular, the radial swivel motor according to FIG. 1 comprises mainly of an outer stator 1 and an inner rotor 2. The stator 1 is composed of a housing 3 and of covers 4 arranged on both faces of the housing 3, which are connected to one another via bolts (not shown). Both covers 4 have a bearing bore each. A cylindrical housing bore, which is split into two opposite free spaces along two opposite and radially directed stator wings, is located in the interior of the housing 3. The rotor 2 includes a driven shaft 5 with bearing journals 6 on both sides and with a cylindrical part 7 lying between them. Two opposite and radially directed rotor wings 8 are arranged in the area of this cylindrical part 7. The rotor 2 is installed in the housing 3 of the stator 1 such that an axis-parallel sealing gap 9 each is formed between the head of the rotor wing 8 and the inner wall of the housing 3 as well as between the head of the stator wing and the peripheral area of the cylindrical part 7. A radial sealing gaps 10 arise between the faces of the rotor wing 8 and the faces of the stator wing and the inner areas of the two covers 4 on both sides. Therefore, each rotor wing 8 splits one of the two free spaces in the housing 3 into a sealing chamber and into an outlet chamber, so that two opposite sealing chambers and two opposite outlet chambers are produced. Both sealing chambers and both outlet chambers are connected to one another by inner channels 11 and 12, respectively, while one of the two sealing chambers is connected to an inlet connection 13 and one of the two outlet chambers is connected to an outlet connection 14. A sliding packing ring 15 is placed axially displaceably on the driven shaft 5 in the transition area from the bearing journal 6 to the cylindrical part 7, so that the sliding packing ring 15, with its radial sliding surface and sealing surface, rests slidingly against the inner surface of the cover 4 and, with its axial sealing surface, rests against the circumferential surface of the driven shaft 5. With these two sealing surfaces, the sliding packing ring 15 seals in the outward direction. Between the internal surface of the sliding packing ring 15 and the rotor wing 8 or the stator wing, there is another radial sealing gap 16, which separates the adjacent pressure and outlet chambers from one another for inner tightness. This sealing gap 16 has an arched design corresponding to the shape of the sliding packing ring 15. As FIG. 2 shows in particular, each rotor wing 8 and likewise each of the stator wings (not shown) has two parallel shanks 17, which form between them a mounting groove 18 for the novel sealing device 19. This mounting groove 18 is arranged in the middle and runs over the entire height and over the entire length of the rotor wing 8 or of the stator wing. The sealing device 19 is pressed into this mounting groove 18. Thus, the sealing device 19 seals the sealing gaps 9, 10 and 16 present on the circumference and on the faces of each rotor wing 8 and stator wing and provides for the inner tightness between the pressure and inlet chambers of the swivel motor. According to FIG. 3, the sealing device 19 consists of a sealing element 20 made of an elastomer, for example, a NBR (nitrile), a HNBR (hydrogenated nitrile) or a FPM (fluorinated rubber). This sealing element 20 has a length and a height, which are coordinated with the length and the depth of the mounting groove 18 in the rotor wing 8 or in the stator wing. A plurality of rigid sealing elements 21, 22, 23, 24 made of plastic are placed on both sides of the soft sealing element 20 and connected to one another in a sandwich-like manner by bonding or vulcanization. PTFE is preferably used as the plastic. The rigid sealing elements 21, 22, 23, 24 on each of the two sides of the soft sealing element 20 are embodied in their lengths and widths, such that they close flush with the soft sealing element 20 with their outer sealing surfaces and are spaced apart from one another by a radial compensating gap 25 and an axis-parallel compensating gap 26. Both compensating gaps 25, 26 on both sides of the soft sealing element 20 intersect, whereby they are arranged, such that the compensating gaps 25, 26 on one side are not overlapped by the compensating gaps 25, 26 on the other side. In terms of width, the soft sealing element 20 and the rigid sealing elements 21, 22, 23, 24 placed thereon are dimensioned, such that, in the sandwich pack, they exceed the width of the mounting groove 18 of the rotor wing 8 or of the stator wing by a press dimension. The width of the radial and axis-parallel compensating gaps 25, 26 depends on the number and on the size of the rigid sealing elements 21, 22, 23, 24. To mount this sealing device 19 into the mounting groove 18 of the rotor wing 8 and of the stator wing, the sealing device 19 is pressed together laterally to a sufficient extent, so that the soft sealing element 20 expands in all longitudinal directions. The rigid sealing elements 21, 22, 23, 24, which are fastened to the soft sealing element 20, also migrate outwards in all longitudinal directions. In this state, the sealing device 19 is pressed into its final position into the mounting groove 18. In the mounting of the thus completed rotor 2 with the housing 3 of the swivel motor, pressure is exerted from the housing 3 onto the expanded soft sealing element 20, and, consequently, the soft sealing element 20 is also pressed together in the front. In this case, the soft sealing element 20 builds up a pretension, which presses all rigid sealing elements 21, 22, 23, 24 against the respective walls of the housing parts. At the same time, the radial and axis-parallel compensating gaps 25, 26 are reduced to a predetermined distance. In this state, the soft sealing element 20 and all rigid sealing elements 21, 22, 23, 24 rest against the housing parts under the pretension of the soft sealing element 20 in a sealing manner. All sealing gaps 9, 10, 16 concerned are thus sealed. During the operation of the swivel motor, compressed oil arrives from the respective pressure chamber laterally between the rigid sealing elements 21, 22, 23, 24 and thus into the radial and axis-parallel compensating gaps 25, 26. The pressure of the oil loads all adjacent rigid sealing elements 21, 22, 23, 24 and drives them apart. These forces thus support the pretension from the soft sealing element 20 on the rigid sealing elements 21, 22, 23, 24. During the motion of the rotor 2, the soft sealing element 20 and the rigid sealing elements 21, 22, 23, 24 slide on the inner walls of the housing parts in a constantly changing direction and thus have a joint share in the sealing function. On top of that, the rigid sealing elements 21, 22, 23, 24 take charge of a support function for the soft sealing element 20, as a result of which the soft sealing element 20 is protected. However, the rigid sealing elements 21, 22, 23, 24 are, to the same extent, subject to an intended abrasion because of the rough surface of the housing parts, as a result of which the unevennesses on the inner walls of the housing parts in terms of the manufacturing technique are exposed to the abrasion and a smooth surface forms on the housing parts. This reduces the sealing gap caused by the manufacture and protects the soft sealing element against premature destruction. In the case of using in a lower temperature range, all components involved in the sealing contract to varying extents depending on the material properties and the dimensions, whereby the contraction of the soft sealing element 20 is the greatest. Because of a greater selected pretension and because of the forces originating from the compressed oil in the radial and axis-parallel compensating gaps 25, 26, the rigid sealing elements 21, 22, 23, 24 are, furthermore, pressed against the inner walls of the housing parts opposite the direction of contraction of the soft sealing element 20. During these motions of all sealing elements 20, 21, 22, 23, 24, the radial and axis-parallel compensating gaps increase. Thus, the sealing function continues to be maintained at low operating temperatures. In the case of using at higher temperatures, all of the components involved in the sealing function expand. From the different tensions during the expansion process, forces occur, which support the pretension of the soft sealing element 20 on the rigid sealing elements 21, 22, 23, 24 and the hydraulic forces in the radial and axis-parallel compensating gaps 25, 26. The tightness increases as a result of this. While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

<SOH> BACKGROUND OF THE INVENTION <EOH>A radial swivel motor usually consists of a housing, which has at least one stator wing in the interior and is closed on the faces with covers, and of a rotor, which is composed of a driven shaft mounted in the covers and at least one rotor wing. The rotor wing is pivotable against the stator wing of the housing only to a limited extent and thus forms, with the stator wing, at least one pressure chamber and one inlet chamber. To guarantee the inner tightness between the pressure chamber and the inlet chamber, both the rotor wing and the stator wing are equipped with a form-fitting sliding sealing element, which rests against the lateral covers and against the inner wall of the housing or against the rotor. Again and again, a great number of tightness problems occur right in this area because the sealing elements are subject to increased wear. This is due to the limited rotary motion of the rotor, which changes again and again, and because the sealing elements are also exposed to a very broad operating temperature range. A few suggestions have already become known for solving these problems. Thus, DE 199 35 234 C1 describes an embodiment of the sliding sealing element, which consists of a filler piece that carries a circular sealing body under pretension, whereby the filler piece is embodied as divided and thus longitudinally mobile parallel to one another, and at least one spring element is arranged between the filler pieces. Thus, the filler pieces are twisted by forces each acting in opposition to one another. The drawback of this sealing variant is that the sealing strip consists of a large number of component parts and thus it is expensive to manufacture and complicated to mount. Moreover, the spring elements consisting of a soft material have only a low volume, so that the pretension forces produced are therefore also very low. What's more, the spring elements only act in the radial direction. All of this leads to leakage. Supporting the action of an elastic pretension element with one or more metal springs integrated in the pretension element is now known from DE 199 27 619 A1, whereby the metal spring may be a diaphragm spring, corrugated spring, coil spring or compression spring. The pretension forces for the sealing elements are increased by means of the additional metal springs; however, this solution can hardly be technically embodied for this purpose. The compression springs must act, namely, in the radial and axis-parallel directions in relation to the axis of rotation and thus the compression springs must also be arranged in an intersecting manner. This requires a very wide mounting space in the axial direction, which is simply not present because of the dimensions of the rotor wing or of the stator wing. On the other hand, DE 199 27 621 A1 discloses a strip-like sliding sealing element that consists of a first square sealing frame made of PTFE, a second square sealing frame made of PTFE and a pretension element made of an elastomer. Both sealing frames and the pretension element are designed as being of the same size and are joined together in a sandwich-like manner into a pack by bonding or by vulcanization, and both sealing frames are arranged offset to one another both in the radial and axial directions. The pretension element is arranged between the two sealing frames and, with corresponding lateral projections, engages in the cavities of the two sealing frames, so that the two sealing frames, when installed in the swivel motor, are pretensioned in opposition by the forces of the pretension element equally in the radial and axial directions. All of the solutions mentioned have in common the fact that the actual sealing element consists of a hard plastic PTFE and is loaded by a corresponding spring element to reduce the sealing gap. This spring element is usually an elastomer material. Sealing elements made of PTFE have good sliding properties, as a result of which they are actually readily suitable for sealing components sliding on one another. However, an open sealing gap, through which compressed oil can overflow, always remains for manufacturing reasons. The size of the sealing gap is, however, also dependent on the operating temperature of the swivel motor. Thus, the sealing gap expands as the temperature becomes lower, while with a higher temperature the contact pressure of the sealing elements at the housing parts increases. With an expanding sealing gap, the waste oil stream increases, and with a higher contact pressure, the wear of the sealing elements increases. Both are unwanted. All the sliding sealing elements mentioned are thus unsuitable for the required temperature range of −40° C. to 130° C.

<SOH> SUMMARY OF THE INVENTION <EOH>Therefore, the basic object of the present invention is to develop a sealing device, whose sealing gaps between the pressure chamber and the inlet chamber of the swivel motor are independent of the temperature. According to the invention, a sealing device or arrangement for a radial swivel motor is provided. The swivel motor includes a stator with at least one stator wing and a rotor with at least one rotor wing, which form at least one sealing chamber and one inlet chamber and which are equipped with a sealing device each for sealing in the inward direction. Each sealing device is pressed into a mounting groove of the rotor wing and a mounting groove of the stator wing. Each sealing device includes outer rigid sealing elements and a pretension element made of an elastomer connecting the outer rigid sealing elements to one another. The sealing device includes a pretension element designed as a soft sealing element. The outer rigid sealing elements have a multipart design, whereby the soft sealing element and the rigid sealing elements are connected undetachably to one another. The circumferential sealing surfaces of the rigid sealing elements, in the unloaded state, close flush with the sealing surface of the soft sealing element. The rigid sealing elements are spaced apart from one another by at least one radial compensating groove and at least one axis-parallel compensating groove. The compensating grooves are arranged on both sides of the sealing device, such that the compensating grooves on one side are not overlapped by the compensating grooves on the other side. The novel sealing device eliminates the above-mentioned drawbacks of the state of the art. Thus, the novel sealing device is primarily characterized by a very good sealing function. This can be mainly attributed to the novel combination of various types of sealing elements. Thus, the novel sealing device breaks with the bias that soft packings are unsuitable for relative motions directed at an angle to the sealing element, as they occur precisely in swivel motors. This is achieved by the rigid sealing elements on both sides of the soft sealing element, which, on the one hand, take charge of a support function for the soft sealing element and which, at the same time, smooth the housing parts, such that the soft sealing element continues to be protected from the unevennesses of the metallic housing parts. The high sealing function can also be attributed to the fact that, now with the two outer rigid sealing elements and the soft inner sealing element, three sealing parts are involved in the sealing function. However, the particular advantage lies in the fact that the sealing device maintains its high sealing function even over a broad temperature range. Thus, the sealing function is largely independent of the temperature. This is achieved because the rigid sealing elements have a multipart design and are each loaded so strongly by the pretension (also referred to as compression) through the soft sealing element and by the hydraulic pressures prevailing in the compensating gaps that each volume contraction is compensated. This contraction is compensated in each direction, i.e., not only in the radial and axis-parallel directions, but also in the diagonal direction. Thus, a constantly high tightness on the entire circumference, i.e., also in the corners of the sealing device is guaranteed. It is particularly advantageous when all the soft and rigid sealing elements are so dimensioned that sufficiently wide compensating gaps arise, so that, after the assembly which is carried out at room temperature, a sufficient gap remains for the contraction compensation. Thus, the sealing function can continue to be maintained even at correspondingly low temperatures. It is also advantageous when the soft sealing element is designed such that the pretension to be achieved can be selected to be greater than the expected contraction of all the components involved in the sealing. This also makes use at low temperatures possible. Furthermore, it is advantageous if the compensating gaps are designed as compressed-oil-carrying channels and are connected to the respective sealing chamber of the swivel motor. Thus, the rigid sealing elements can be loaded with a hydraulic pressure, whose forces support the pretension forces. This increases the tightness over the entire temperature range. It is also advantageous if the soft sealing element and the rigid sealing elements are undetachably connected to one another by bonding or by vulcanization. As a result of this, the entire sealing device becomes one component, which greatly reduces the assembly effort of the swivel motor. The present invention shall be explained in detail based on exemplary embodiments. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.

20060829

20081028

20070726

96367.0

H02K510

LAZO, THOMAS E

SEALING DEVICE FOR A RADIAL SWIVEL MOTOR

UNDISCOUNTED

ACCEPTED

H02K

ACCEPTED

Cleaning assembly

A portable conveyor cleaning assembly with adjustable first and second end assemblies selectively mountable on respective sides of different width conveyors. A carriage is movable reciprocally over the conveyor to direct a cleaning fluid onto the conveyor, with the degree of reciprocal movement being adjustable to suit a particular conveyor.

1-21. (canceled) 22. A portable cleaning assembly, the assembly including an elongate reciprocal movement providing means, said means including an elongate body and a carriage member movable in a reciprocal manner along a required proportion of the body, a cleaning member mounted on the carriage for cleaning an item, the assembly also including a first engagement member engageable with an item to be cleaned towards a first side of the item, and a second engagement member engageable with the item towards an opposite side thereof, the second engagement member being adjustably mounted on said elongate body so as to be provided at a required spacing from the first engagement member for a particular item to be cleaned. 23. An assembly according to claim 22, wherein the second engagement member is slidably mounted on the elongate body. 24. An assembly according to claim 22, wherein means are provided for locking the second engagement member at a required position on the body. 25. An assembly according to claim 22, wherein the first and/or second engagement members include height adjustment means engageable with the item to provide the cleaning member at a required spacing from the item. 26. An assembly according to claim 22, wherein the reciprocal movement providing means includes a selectively rotatable endless line means located in the body, with the carriage member attached to the line means. 27. An assembly according to claim 26, wherein the line means is a belt or chain. 28. An assembly according to claim 22, wherein the reciprocal movement providing means includes clutch means such that the carriage member will not move if a resistive force above a predetermined level is encountered. 29. An assembly according to claim 22, wherein the speed of reciprocal movement is selectively adjustable. 30. An assembly according to claim 22, wherein the cleaning member includes means for projecting fluid onto the item. 31. An assembly according to claim 30, wherein the fluid is any of steam, water or other liquid, or air. 32. An assembly according to claim 22, wherein the cleaning member is engageable with the item. 33. An assembly according to claim 32, wherein the cleaning member includes any of a rotating or fixed brush, vacuum system, or scraper. 34. An assembly according to claim 22, wherein the assembly includes a removable safety cover. 35. An assembly according to claim 34, wherein the assembly is configured so as to only be operable when the safety cover is in place. 36. An assembly according to claim 34, wherein the safety cover is locatable in formations on the first and second engagement members. 37. An assembly according to claim 36, wherein the formations are slots. 38. An assembly according to claim 22, wherein the proportion of the elongate body along which the carriage moves is adjustable. 39. An assembly according to claim 38, wherein the proportion of the elongate body along which the carriage moves is manually adjustable. 40. An assembly according to claim 38, wherein one or more sensors is provided on the elongate body to detect the position of the carriage to cause a required limitation of the movement thereof along the body. 41. An assembly according to claim 38, wherein the assembly is arranged such that the proportion of the elongate body along which the carriage moves is automatically determined by the location of the second engagement member on the elongate body. 42. A portable conveyor cleaning assembly, wherein the assembly is according to claim 22, with the first and second engagement members being locatable on respective side structures of a conveyor.

This invention relates to a portable cleaning assembly, and particularly but not exclusively such an assembly for cleaning conveyors. Conveyors are used in a wide range of applications including for instance the food industry. In establishments such as bakeries a number of such conveyors may be used, which conveyors may be a wide range of different widths. Such conveyors often have a mesh or interlinked structure and difficulties can be encountered in cleaning such conveyors. If adequate cleaning is not carried out this can result in spoiling of the food products. The use of chemical cleaners which can enhance cleaning, can however result in potential contamination of food products. To provide an adequate cleaning assembly on each conveyor will, often however prove prohibitively expensive. According to the present invention there is provided a portable cleaning assembly, the assembly including an elongate reciprocal movement providing means, said means including an elongate body and a carriage member movable in a reciprocal manner along a required proportion of the body, a cleaning member mounted on the carriage for cleaning an item, the assembly also including a first engagement member engageable with an item to be cleaned towards a first side of the item, and a second engagement member engageable with the item towards an opposite side thereof, the second engagement member being adjustably mounted on said elongate body so as to be provided at a required spacing from the first engagement member for a particular item to be cleaned. The second engagement member is preferably slidably mounted on the elongate body, and means may be provided for locking the second engagement member at a required position on the body. The first and/or second engagement members may include height adjustment means engageable with the item to provide the cleaning member at a required spacing from the item. The reciprocal movement providing means may include a selectively rotatable endless line means located in the body, with the carriage member attached to the line means. The line means may be a belt or chain. The reciprocal movement providing means may include clutch means such that the carriage member will not move if a resistive force above a predetermined level is encountered. The speed of reciprocal movement is preferably selectively adjustable. The cleaning member may include means for projecting fluid onto the item, which fluid may be any of steam, water or other liquid, or air. In an alternative arrangement the cleaning member may be engageable with the item, and the cleaning member may include any of a rotating or fixed brush, vacuum system, or scraper. The assembly may include a removable safety cover, and the assembly may be configured so as to only be operable when the safety cover is in place. The safety cover may be locatable in formations on the first and second engagement members, which formations may be slots. The proportion of the elongate body along which the carriage moves may be adjustable, and may be manually adjustable. One or more sensors may be provided on the elongate body to detect the position of the carriage to cause a required limitation of the movement thereof along the body. The assembly may be arranged such that the proportion of the elongate body along which the carriage moves is automatically determined by the location of the second engagement member on the elongate body. The invention also provides a portable conveyor cleaning assembly, the assembly being according to any of the preceding nine paragraphs, with the first and second engagement members being locatable on respective side structures of a conveyor. An embodiment of the present invention will now be described by way of example only and with reference to the accompanying drawings, in which: FIG. 1 is a diagrammatic side view of a cleaning assembly according to the invention in use in cleaning a first conveyor; FIG. 2 is a similar view to FIG. 1 but with the assembly cleaning a second wider conveyor; FIG. 3 is a diagrammatic end view of the assembly of FIGS. 1 and 2; and FIGS. 4 and 5 are respectively plan views of the assembly in use on the first and second conveyors. The drawings show a cleaning assembly 10 in use cleaning either a first conveyor 12 or a second wider conveyor 14. The conveyors 12, 14 each comprise a mesh belt 16 which extends between side structures 18. The assembly 10 comprises a control box 20 including a supply 22, in this instance of steam. An elongate variable speed reciprocal movement providing means 24 extends laterally from the control box 20 and includes an elongate rectangular cross-section body 26. Located within the body 26 is an endless belt (not shown) driven by an appropriate mechanism (not shown) including a clutch configuration which permits slippage to occur if a reactive force above a predetermined level is encountered thereby. A slot (not shown) is provided on the underside of the body 26 to provide access to the belt, and a carriage 28 is mounted to the belt through the slot. The carriage 28 carries a cleaning member in the form of a manifold 30 with a plurality of downwardly directed jets 32. A supply pipe 34 extends from the manifold 30 and is carried by a flexible conduit 36 in a loop on top of the body 26, to connect to the steam supply 22. First and second end assemblies 38, 40 are provided. The first assembly 38 is attached to the control box 20. The assembly 38 includes a spaced pair of height adjusters 42 engageable with the respective conveyor side structure 18. Each height adjuster 42 includes an F shape section bracket 44 which locates a threaded thumb wheel 46 between the side limbs of the F, with a foot 48 below the side limbs of the F, mounted on a threaded bar extending through the bracket 44, such that rotation of the thumb wheel 46 raises and lowers the foot 48. Two similar spaced height adjusters 42 are provided on the second end assembly 40. The end assembly 40 is slidably mounted on the elongate body 26 by virtue of a sleeve arrangement 52. Two clamp screws 54 extend in to the sleeve arrangement 52 such that tightening of the screws 54 locks the sleeve arrangement 52, and hence end assembly 40, on the body 26. A safety guard 56 in the form of a mesh cage is provided which locates in four slots 58, each provided on a respective side of one of the end assemblies 38, 40. The slots 58 enable relative movement between the end assembly 40 and the guard 56, allowing the same guard 56 to be used in different locations. A proximity safety switch 60 is provided on the fixed end assembly 38 spaced from a one of the slots 58. The safety switch 60 is connected to the control box 20 to prevent operation of the assembly 10 if the safety guard 46 is not detected as being in position. In use with the clamp screws 54 loosened, the end assembly 40 can be slid to an appropriate position on the body 26 to fit on the side structure 18 of a particular conveyor. Once the height adjusters 42 are located in correct positions on the respective side structures 18, the clamp screws 54 can be tightened to provide a required operating width for the assembly 10. The height adjusters 42 can then be adjusted by manipulating the respective thumb wheels 46 to provide a required height of the jets 32 above the mesh conveyor 16. Once a correct height has been determined, using the control box 20 the amount of reciprocal movement of the carriage 28 and hence jets 32 can be set to provide full cleaning of the mesh 16. The amount of reciprocal movement of the jets 32 is shown by the line 62 in FIGS. 1 and 4. One or more sensors (not shown) may be provided on the assembly to detect the position of the carriage or jets. The amount of movement may be determined as the amount of permitted movement from the sensor or sensors. The speed of the reciprocal movement can be set as required for the type/speed of conveyor belt, and/or the level of soiling. When required the assembly 10 can readily be moved for use with a different conveyor such as the wider conveyor 14 as shown in FIGS. 2 and 5. For use on the conveyor 14, the safety guard 56 is lifted off, and following loosening of the screws 54 the end assembly 40 will be moved to the left as shown in the drawings. Once the assembly 10 is correctly fitted on to the conveyor 14, the safety guard 56 is replaced so as to locate in the slots 58 irrespective of the position of the end assembly 40. The control box 20 is used to provide a greater extent of reciprocal movement of the jets 32, as shown by the line 64. If required extra height adjustment can be obtained by altering the mounting of the height adjusters 42 on the end assemblies 38, 40. FIG. 3 illustrates the height adjusters 42 mounted to a middle pair of mounting holes 66, but alternative lower and higher mounting holes 68 are illustrated. Such holes may be usable for example where there is a particular recess on a conveyor. There is thus described a portable cleaning assembly 10 usable on a wide range of different size, conveyors. This means that one or more such assemblies could be used in a particular location to clean a wide range of different size conveyors, thus making it economically practical to clean a number of different size conveyors, whilst only requiring one or more cleaning assemblies. The same safety guard is usable with different size conveyors. The height adjustment in the assembly 10 permits thorough cleaning of conveyors, even where these have a somewhat different configuration. The assembly has a relatively straightforward configuration and can thus be inexpensively and robustly manufactured for regular low maintenance operation in a wide range of locations. Various modifications may be made without departing from the scope of the invention. For example, a different cleaning system may be used, and rather than steam, a liquid such as water or a chemical cleaner may be used, or air could also be used. It may be that a contact cleaning process is used. For instance, a rotating or fixed brush could be used, or alternatively a vacuum system, scraper or other arrangement could be provided. A different safety guard can be provided. For instance with some cleaning systems a solid rather than mesh guard may be provided. A solid guard contains splashes, whilst a mesh guard prevents build up of condensation. Rather than a manual adjustment of the reciprocal movement, sensors could be provided such that the amount of linear movement is automatically determined by the spacing between the end assemblies. Reciprocal movement could be provided other than by an endless belt, and could be provided by a screw mechanism or pneumatic operation. The movement of the cleaning member in use need not be in a reciprocal manner, and the cleaning member could operate only, or particularly, at specific parts of a conveyor or other item to be cleaned. The invention is usable in cleaning arrangements for a wide range of applications other than conveyors. Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

20060829

20100831

20070726

98153.0

B65G4522

PERRIN, JOSEPH L

PORTABLE CONVEYOR CLEANING ASSEMBLY

SMALL

ACCEPTED

B65G

ACCEPTED

Device for introducing a catheter with a security non-piercing cage provided with a flexible blade

A device for introducing a catheter into a body site through the skin by means of an security non-piercing cage includes a steel spring flexible blade which is disposed in the cross section of the chamber of the nonpiercing cage near the proximal input thereof perpendicularly to a needle and is penetrable by the needle. The blade and the needle are adapted to interact in such a way that the blade is in a resting position and freely transversable by the needle when the needle is pushed in a distal direction, and the blade stops the needle and is flexed thereby when the needle is pulled in a proximal direction beyond a determined axial position in such a way that the flexed blade tilts the needle and exposes the inclined needle to a restoring force which pushes the needle off in the distal direction until the puncture end is stopped against the chamber wall. The invention can be used for intravenous catheters.

1. An arrangement for the insertion into the body, through the skin, of a catheter with a proximal base , where this arrangement includes a needle which has a puncture end and a cage, which extends the base in the proximal direction, where this chamber forms a chamber through which the needle slides from a proximal entrance to an opposite distal exit and is equipped with a sprung flexible steel blade, to hold the puncture end of the needle in the chamber when the needle is withdrawn from the cannula, wherein this blade is positioned across the chamber close to the proximal entrance of the chamber perpendicular to the needle and traversed by the needle, where the blade and the needle include resources that combine so that the blade is at rest and traversed freely by the needle when the needle is pushed in the distal direction, and so that the blade stops the needle and is bent by the needle when the needle is drawn in the proximal direction beyond a given axial position, so that the bent blade inclines the needle and applies a return force to the needle which tends to force the needle back in the distal direction until the puncture end comes up against a wall of the chamber. 2. An arrangement according to claim 1 in which the flexible blade has a perforation for the passage of the needle, and ahead of the said perforation, the needle has its section modified locally so that this section is stopped by the perforation in the blade during the withdrawal movement of the needle in the proximal direction, this modified section being located at a distance from the puncture end of the needle so that the contact of the modified section with the perforation in the blade occurs after this end has arrived in the chamber during the operation for removal of the needle. 3. An arrangement according to claim 1, in which the chamber has an end wall in the distal direction which includes a groove into which the puncture end of the inclined needle enters. 4. An arrangement according claim 1, in which the flexible blade constitutes a branch of a blade shaped as an L, and which has a longitudinal branch fixed to a longitudinal wall of the chamber and a transverse branch which constitutes the flexible blade equipped with a perforation for the passage of the needle. 5. An arrangement according to claim 1, in which the flexible blade is shaped as a U, constituting a first rear transverse branch located at the entrance of the chamber, and equipped with a perforation for the passage of the needle, and a second front transverse branch parallel to the first branch, located in the said chamber and equipped with a perforation for the passage of the needle, where the perforation of the rear branch is not sufficiently large to allow passage of the modified section of the needle, but the perforation of the front branch is able to allow this to pass. 6. An arrangement according to claim 5, in which the catheter base has an external rim and the cage includes a mobile lever which has a stop dog locked to this rim in one position of the lever, and in which the second branch of the flexible blade is continued by a third branch more or less at the bracket of the second branch, and which operates the said lever to release the dog. 7. An arrangement according to claim 1, in which, ahead of the chamber, the cage includes a nose which slots into the catheter base and which is traversed longitudinally by an aperture for the passage of the needle. 8. An arrangement according to claim 1, in which the needle is equipped with a base and in which the cage includes a transverse plate projecting laterally, against which presses one wall of the base of the needle when the needle is in its working position. 9. An arrangement according to claim 8, in which the said blade is suspended from the said plate of the cage. 10. An arrangement according to claim 1, in which the needle includes a base bearing against the flexible blade when the needle is in its working position. 11. An arrangement according to claim 1, wherein said catheter is a short catheter and said arrangement is adapted for the insertion of said short catheter into a vein.

The invention aims to eliminate the risks of accidental pricking on removal of a puncture needle employed for the insertion of a catheter into any part of the body through the skin. A large number of such prick-prevention arrangements have been proposes for this purpose. Publication FR 2 836 385 describes an arrangement in which whole needle with its base is trapped within a case after its removal. Publications EP 0 554 841 and U.S. Pat. No. 5 322 517 describe safety resources which include a cage to trap the point of the needle after its removal, where this cage contains a sprung steel blade which has a branch traversed by the needle, and another branch which is pre-stressed by the needle in an inactive position in which it bears laterally against the needle and which, in its active position, moves in front of the needle when this contact is removed due to withdrawal of the needle. Publication EP 0 753 317 describes a cage which slides on the needle and which includes a sprung steel blade pre-stressed by contact with the needle in an inactive position for as long as the needle traverses the cage, and which is freed and acts to divert the needle when the latter has entered into in the cage. Publication U.S. Pat. No. 5 447 501 describes an arrangement which includes a spring which is pre-stressed by the needle in an inactive position, and which diverts the needle when it is freed by withdrawal of the needle. Other cage arrangements are also described in publications EP 0 456 694 (or U.S. Pat. No. 5 322 517), U.S. Pat. No. 623 499, U.S. Pat. No. 5 176 655, and EP 0 891 198 (or U.S. Pat. No. 6 001 080). One objective of this present invention is to provide a simple cage and flexible blade arrangement, operating automatically, and in which the blade is not prestressed by the needle. The invention concerns and arrangement for the insertion of a catheter into any part of the body, in particular a vein, through the skin, this catheter being equipped with a proximal base, where this arrangement includes a needle with a puncture end and also includes an anti-prick cage which extends the catheter base in the proximal direction, where this chamber forms a chamber through which the needle slides from a proximal entrance to a distal exit, and is equipped with sprung flexible steel blade to hold the puncture end of the needle in the chamber when the needle is withdrawn from the cannula, this blade being positioned across the chamber close to the proximal entrance of the chamber perpendicular to the needle and traversed by the needle, with the blade and the needle including resources that combine so that the blade is at rest and traversed freely by the needle when the needle is pushed in the distal direction and so that the blade stops the needle, and is bent by the needle, when the needle is drawn in the proximal direction beyond a given axial position, so that the bent blade inclines the needle, and applies a return force to the needle which tends to force the needle back in the distal direction until the puncture end of the inclined needle comes up against a wall of the chamber. In a preferred implementation, the flexible blade has a perforation for the passage of the needle, and the needle has a section of the needle modified locally so that it can be stopped by the perforation in the blade during the withdrawal movement of the needle, this modified section being located at a distance from the puncture end of the needle so that the contact of the modified section with the perforation in the blade occurs after this end has entered into the chamber during the withdrawal movement of the needle. In preferred methods of implementation, the invention also has one or more of the following characteristics: the chamber has an end wall in the distal direction which forms a groove in which the puncture end of the inclined needle lodges; ahead of the chamber, the cage has a nose which fits, without locking, into the catheter base, and which is traversed longitudinally by an aperture for the passage of the needle; the catheter base has an external rim, and the cage includes a device which has a dog which locks onto this rim for temporary attachment of the cage to the base; the dog comprises the end of a lever, and the flexible blade is shaped to operate by contact with this lever so as to free the dog from the rim of the catheter base when the blade has been sufficiently deflected. The following description is of various implementations of an arrangement according to the invention for the insertion of a short catheter into a vein, with reference to the appended drawings in which: FIG. 1 shows, in longitudinal section, a first implementation, ready for use, with the flexible blade shown at rest; FIG. 2 shows the implementation of FIG. 1 during 30 two successive stages of the operation to withdraw the needle; FIG. 3 shows the assembly of FIG. 1 after separation of the cage and the cannula; FIG. 4 is a magnified view of a detail of the assembly of FIG. 2; FIG. 5 shows, in longitudinal section, an implementation variant of the assembly of FIG. 1, ready for use, with the flexible blade shown at rest; FIG. 6 shows the implementation of FIG. 5 during successive stages of the operation to withdraw the needle; FIG. 7 is a magnified view of a detail of the assembly of FIG. 6; FIG. 8 is a magnified view of the same detail, during a later stage of the withdrawal; FIG. 9 shows, in longitudinal section, another implementation of an assembly according to the invention, ready for use, with the flexible blade shown at rest; FIG. 10A is a view in perspective of an assembly according to FIG. 9, in which the base of the needle has been omitted, in which the assembly has been cut in two by a longitudinal plane of symmetry, and in which the needle has been withdrawn until the point of the needle is on the point of emerging into the chamber of the cage; FIG. 10B is similar to FIG. 10A, during a later withdrawal stage, the point of the needle having arrived in the chamber of the cage, and the needle causing a deflection of the flexible blade; FIG. 10C is similar to FIG. 10B, during a later stage in which the flexible blade has been pushed back by the needle until the point of the needle comes up against the front wall of the chamber of the cage; FIG. 11 shows the assembly of FIG. 9 after 30 separation of the cage and the cannula; FIG. 12 is a magnified view of a detail of the assembly of FIG. 9; FIG. 13 shows, in longitudinal section, another implementation of an assembly according to the invention, ready for use, with the flexible blade shown at rest; FIG. 14 shows the implementation of FIG. 13 during successive stages of the operation to withdraw the needle; FIG. 15 shows the implementation of FIG. 13 after separation of the cage and the cannula, and FIG. 16 is a magnified view of a detail of the assembly of FIG. 12. The figures show a cannula composed of a short tubular catheter (1) equipped with a proximal base (2), a needle (3) which has a puncture end (3a) and which is equipped with a proximal base (4), and an anti-prick cage. The cage (5) forms a chamber (6) which has a proximal needle entrance (7) oriented toward the base of the needle, and an opposite end wall (8) which has a distal needle exit (9) oriented toward the catheter base. Preferably, the end wall of the chamber forms a groove 20 around the exit from the chamber (10). Ahead of the chamber, the cage includes a nose (11) which fits, without locking, into the catheter base, and which is traversed longitudinally by an aperture (12) for the passage of the needle. The catheter base has an external rim (13), composed of one of the threads on the base for example, when the latter is threaded on the outside, and the cage includes a mobile dog (14) which locks onto this to hold the cage onto the base in a removable manner. In the implementations of FIGS. 1 and 5, the cage includes a sprung steel blade shaped as an L, which has a longitudinal branch (16) fixed to a longitudinal wall of the chamber, and a flexible transverse branch (17) located close to the proximal entrance (7) of the chamber and equipped with a perforation (19) lined up with the exit (9) of the chamber when this flexible branch is at rest (FIGS. 1 and 5) for the passage of the needle. In a manner which is known of itself, the needle has a local change of section chosen so as not to compromise the sliding of the needle in the cannula while also being large enough to be stopped by the perforation (19) in the flexible branch of the blade which is located at the entrance of the chamber In the implementations of FIGS. 9 and 13, the flexible branch (17) is shaped as a U, constituting a rear transverse branch (17a) located to the entrance of the chamber and equipped with a perforation (19) for the passage of the needle, and a front transverse branch (17b) parallel to the first branch, located in the said chamber and equipped with a perforation (20) for the passage of the needle and sufficiently wide to also allow passage of the said modified section of the needle, while the perforation (19) stops this modified section. The perforations (19 and 20) are aligned with each other and aligned with the exit of the chamber when the flexible branch is at rest. By way of guidance, and in no way limiting, two examples of such a modification have been shown which are known in themselves, namely respectively, a modification in the form of a local bulge (21) in the wall of the needle (FIG. 4) and a modification composed of a slot (22) in this wall (FIGS. 7 and 8). In the first case, the perforation (19) in the flexible blade can be merely cylindrical, while in the second case, the blade has claws (23) at the position of the perforation which are designed to bite into the wall of the needle. In the first case, it can be seen that the needle will not be blocked in the blade and will still be able to slide in the distal direction (toward the front) while in the second case the needle will be blocked. In all cases, the modification will be effected after threading of the needle. This U-shaped blade guides the needle at two points and obliges it to assume the orientation imposed by the deviation of the blade. In the implementations of FIGS. 9 and 13, the cage includes a transverse plate (24) projecting laterally and against which presses one wall (25) of the base (4) of the needle when the needle is in its working position. In the implementations of FIGS. 9 and 13, the flexible blade (17b) is suspended by a branch (17d) turned onto the transverse plate (24) of the cage. In the implementation of FIG. 13, in order to allow the separation of the cage from the catheter base, the dog (14) used for the temporary attachment of the cage to the base constitutes the end of a lever (26), and the flexible blade is shaped to operate by contact with this lever so as to free the dog from the rim of the catheter base when the blade has bent sufficiently. In the case presented as an example only, the flexible blade includes, for this purpose, a third branch (17c), which continues the second branch more or less at right angles to this branch, and which presses onto this lever to operate it when the blade bends. The arrangement of FIG. 1 is applied as follows: After effecting the vein penetration with the arrangement as shown in FIG. 1, the catheter is pushed toward the front into the vein while holding the needle, with the cage remaining attached to the catheter base and moving away from the base of the needle. When the catheter is in place, the needle is drawn backwards while holding the catheter (FIG. 2), until the bulge of the needle makes contact with the hole of the blade which it cannot cross. By continuing the rearward traction on the needle, the blade is bent elastically and the bevelled end of the needle enters into the chamber. The deformation of the blade causes its hole to move off axis and as a consequence moves the needle off axis, this inclining within the chamber. By continuing the rearward traction, the cage is finally detached from the catheter base (FIG. 3). The flexible blade then returns to its rest position and pushes the needle back by means of the bulge. The diverted bevelled end enters into the groove created around the exit of the chamber, where it is immobilised. In the variant of FIG. 5, by drawing the needle to the rear, the slot in the wall of the needle is brought to the level of the claws of the blade. The claws dig into the latter and ensure axial immobilisation of the needle. By continuing the withdrawal movement of the needle, the blade is deformed, the cage separates from the cannula, and the blade returns to its original position. Even if the bevelled end were to succeed in recentring itself in the hole, the bevelled end will be blocked in the cage. A user who wanted to re-engage the bevelled end in the distal exit of the chamber could not do so. The implementation of FIG. 9 is used like the preceding implementations, and has the advantage of even greater safety due to the fact that the needle is guided by the two perforations in the flexible U-shaped blade, which combine to constrain it to incline when the blade is bent. In the implementation of FIG. 13, the traction on the needle, blocked fully back in the chamber, leads to a rearward traction on the blade. When the puncture end of the needle is in the chamber, the retention dog is able to mount onto the collar of the base so as to escape to the rear, allowing the cage to separate from the base. The invention is not limited to these examples of implementation.

20061016

20100323

20070816

57653.0

A61M5178

FLICK, JASON E

DEVICE FOR INTRODUCING A CATHETER WITH A SECURITY NON-PIERCING CAGE PROVIDED WITH A FLEXIBLE BLADE

UNDISCOUNTED

ACCEPTED

A61M

ACCEPTED

Method and Apparatus of Managing Wireless Communication in a Worksite

A method of controlling wireless messaging between mobile apparatuses and an onsite office in a worksite comprises the steps of: dividing the worksite area into elementary cells (C) mapped in correspondence with the topology of the area and into and communication zones (CZ), for a given communication zone of the worksite, establishing at least one updatable communication attribute value pertaining to a parameter of wireless communication to or from the given cell or communication zone, for a given elementary cell, establishing at least one worksite management attribute value of the worksite at that cell, the worksite management attribute value pertaining to a parameter other than a wireless communication parameter, storing, in an electronic memory (20), values of the worksite and communication attributes, each stored attribute value being electronically indexed to the elementary cell, or to the communication zone, for which it was determined, forming a worksite management message with an electronically readable content containing at least one worksite management attribute value, accessing the memory to obtain at least one current communication attribute value in respect of a cell or communication zone to or from which the formed management message is to be communicated by a wireless communication, and establishing a wireless communication to or from the communication zone to send or receive the management message on the basis of the current communication attribute value(s) electronically accessed from the memory.

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A method of controlling wireless messaging in a worksite area, in which worksite management messages are received by, or sent from, communicating entities operating within said worksite, comprising the steps of: dividing at least part of said worksite area into elementary cells mapped in correspondence with the topology of said area, or into said cells and determined communication zones; for a given cell or communication zone of said worksite, establishing at least one communication attribute value pertaining to a parameter of wireless communication to or from said given cell or communication zone; for a given cell, establishing at least one worksite management attribute value of the worksite for said given cell, said worksite management attribute value pertaining to a parameter other than a said communication attribute parameter; storing, in a memory, values of said worksite management and communication attributes, each stored attribute value being electronically indexed to the elementary cell, or to the communication zone, for which it was determined; forming a said worksite management message with an electronically readable content containing at least one worksite management attribute value; accessing said memory to obtain at least one current communication attribute value in respect of a cell or communication zone to or from which said formed management message is to be communicated by a wireless communication; and establishing a wireless communication to or from said cell or communication zone to send or receive said management message on the basis of said current communication attribute value(s) electronically accessed from said memory. 52. Method according to claim 51, wherein said memory is provided as a common resource whose contents are accessible to communicating parties exchanging worksite management messages. 53. according to claim 51, wherein said at least one communication attribute is at least one of the members of the set of following attributes: a communication frequency or channel allocation; a signal strength indicator, indicating a signal strength to use; a bandwidth capacity indicator; a detected signal-to-noise ratio; data communication security parameters, such as encryption/decryption codes, keys; data messaging format information; and data transmission protocol information. 54. Method according to claim 51, comprising the act of indexing in said memory worksite management attributes and communication attributes to a common elementary cell to which they pertain. 55. Method according to claim 51, further comprising the acts of: analysing a detected wireless communication signal at a determined elementary cell or communication zone; determining, on the basis of said analysis, whether a value of a said communication attribute of that signal is appropriate under current wireless communication conditions; and if said value of a said communication attribute is determined not to be appropriate, sending a message to said memory to cause the value of said communication attribute to be updated to an appropriate value, or to adjust the value of another communication parameter. 56. Method according to claim 55, further comprising sending a message directly to the source of said detected wireless signal to cause said source to update the value of said communication attribute to an appropriate value or to adjust the value of another communication parameter. 57. Method according to claim 51, wherein for at least one communication attribute, said memory stores a plurality of values indexed as a function of at least one of the following set: a classification of the wireless communication sending party; a classification of the wireless communication receiving party; a classification of a worksite management attribute to be conveyed in a said worksite management message; a location of the wireless communication sending party; and a location of the wireless communication receiving party. 58. Method according to claim 51, further comprising the act of establishing or maintaining a radio link at a receiving party, comprising the steps of: accessing at least one stored communication attribute value; and automatically configuring receiver means of said receiving party on the basis of a said accessed communication attribute value(s). 59. Method according to claim 51, comprising the act of establishing or maintaining a radio link at a transmitting party, comprising the steps of: accessing at least one stored communication attribute value; and automatically configuring transmitter means of said transmitting party on the basis of a said accessed communication attribute value(s). 60. Method according to claim 51, wherein a said communication attribute is a radio frequency or channel allocation, for exchanging data with a remote resource, said method further comprising the act of automatically updating and using said updated radio frequency or channel allocation as a function of communication conditions. 61. Method according to claim 51, wherein a said communication attribute is signal strength indicator specifying a modulation or carrier signal strength value to use for a transmission in a communication link, said method further comprising the acts of: detecting a received signal strength at a receiving party; determining whether said received signal strength is below a threshold; and if the received signal strength is below the threshold, sending a message by the receiving party to correspondingly update said signal strength indicator value in said memory accessible to communicating parties. 62. Method according to claim 51, wherein a said communication attribute is a bandwidth capacity parameter expressing the bandwidth capacity limit of a given carrier or channel over a given communication link, said method further comprising the acts of: determining the current amount of occupied bandwidth of a given communication carrier or channel; comparing said current amount of occupied bandwidth with the bandwidth capacity limit, indicated by said bandwidth capacity parameter, for that given communication carrier or channel, to determine if a determined saturation criterion is reached; and in the affirmative, sending a message to said memory and/or to communicating parties concerned, requesting to use another carrier or channel. 63. Method according to claim 51, wherein said stored worksite and communication attribute parameter values are organised in a three-dimensional matrix of which the first and second dimensions map the topology of said worksite area and define the locations of said elementary cells or communication zones, and the third dimension corresponds to the set of worksite management and communication attribute parameter(s). 64. Method according to claim 51, wherein a said elementary cell is dimensioned as a function of at least one of the following set: the variation in contour at said cell; the variation in contour at the immediate vicinity of said cell; the rate of variation with respect to position in the value of at least one data to be managed; and the type of tool(s) scheduled to operate in the area occupied by said elementary cell. 65. Method according to claim 51, wherein dimensions of elementary cells are variable over said worksite area. 66. Method according to claim 51, wherein communication attribute and/or worksite management attribute values are acquired and communicated and/or stored by mobile apparatus as they are conducting site modifying tasks on the worksite. 67. Method according to claim 51, further comprising the acts of: interrogating at least one source of dynamically updatable data, on board mobile apparatus active on said worksite, capable of delivering at least one current attribute parameter value for a communication attribute and/or for a worksite management attribute; determining the geographical location at which said current value(s) is/are acquired; and storing said attribute parameter value(s) acquired at said interrogating step, in association with the cell or communication zone corresponding to the said determined geographical location, as an updated communication attribute and/or a worksite management attribute parameter value. 68. Method according to claim 67, wherein a said updated communication attribute and/or worksite management attribute value is sent to a remote data management resource for dynamically updating said stored data values by at least the acts of: forming a message containing said communication attribute and/or a worksite management attribute parameter value(s) and said geographical location data; and sending said message to said remote data management resource. 69. Method according to claim 51, further comprising the acts of: interrogating at least one source of dynamically updatable data on board said mobile apparatus, capable of delivering at least one current communication attribute and/or worksite management attribute parameter value; determining the geographical location at which said current value(s) is/are acquired; and associating and locally storing said current communication attribute and/or worksite management attribute parameter value(s) and said geographical location data on board said mobile apparatus. 70. Method according to claim 69, further comprising the act of uploading said communication attribute and/or a worksite management attribute parameter value(s) and said geographical location data from said mobile apparatus to a remote data management resource at a determined updating moment. 71. Method according to claim 51, wherein the value(s) of at least one said communication attribute and/or worksite management is/are dynamically updatable, and acquired and communicated on-the-fly by, and as, a mobile apparatus performs worksite modifying tasks evolves over said worksite area. 72. Method according to claim 51, wherein at least one worksite management attribute relates to physical or chemical material characteristics of said worksite and/or physical or chemical atmospheric characteristics of said worksite. 73. Method according to claim 51, wherein at least one worksite management attribute parameter value is inferred from operating parameters of a site-modifying apparatus operative in said worksite area. 74. Method according to claim 51, wherein at least one worksite management attribute value is established prior to site modifying operations on said worksite and relates to a non-dynamic land characteristic of said worksite. 75. Method according to claim 51, wherein said at least one worksite management attribute value is established prior to site modifying operations on said worksite and relates to operating characteristics of mobile apparatus. 76. Method according to claim 51, wherein said at least one worksite management attribute value is established prior to site modifying operations on said worksite and relates to legal, administrative, or contractual data associated to said worksite. 77. Method according to claim 51, wherein at least one worksite management attribute relates to a reference level, its value for a cell expressing reference level value with respect to which elevation/depth values are established for that cell. 78. Method according to claim 51, further comprising the act of preparing an individualised dataset specific to an identified site-modifying mobile apparatus, said individualised dataset comprising selected communication attribute and/or a worksite management attribute parameter values for the requirements of that site-modifying mobile apparatus. 79. Method according to claim 78, wherein said individualised dataset relates only to cells of a region of said worksite where said site-modifying apparatus is programmed to be present over a determined time window. 80. A storage medium containing an individualised dataset specific to an identified site-modifying mobile apparatus, said individualised dataset being prepared specifically for the execution of the method according claim 51, and comprising selected data elements of said attribute worksite management and/or communication attribute parameters for the specific requirements of that site-modifying mobile apparatus. 81. Storage medium according to claim 80, wherein said individualised dataset relates only to cells of a region of said worksite where said contour-modifying apparatus is programmed to be present over a determined time window. 82. Code executable by processor means, said code causing said processor means to carry out the method according to claim 51. 83. A system for controlling wireless messaging in a worksite area, in which worksite management messages are received by, or sent from, communicating entities operating within said worksite, at least part of said worksite area being divided into elementary cells mapped in correspondence with the topology of said area, or being divided into said cells and determined communication zones, said system comprising: means for establishing, for a given cell or communication zone of said worksite, at least one communication attribute value pertaining to a parameter of wireless communication to or from said given cell or communication zone; means for establishing, for a given elementary cell, at least one worksite management attribute value of the worksite for said given cell, said worksite management attribute value pertaining to a parameter other than a said wireless communication parameter; memory means for storing values of said worksite management and communication attributes, each stored attribute value being electronically indexed to the elementary cell, or to the communication zone, for which it was determined; means for forming a said worksite management message with an electronically readable content containing at least one worksite management attribute value; means for accessing said memory to obtain at least one current communication attribute value in respect of a cell or communication zone to or from which said formed management message is to be communicated by a wireless communication; and means for establishing a wireless communication to or from said cell or communication zone to send or receive said management message on the basis of said current communication attribute value(s) electronically accessed from said memory. 84. System according to claim 83, wherein said at least one communication attribute is one of the members of the following set of attributes: a communication frequency or channel allocation; a signal strength indicator, indicating a signal strength to use; a bandwidth capacity indicator; a detected signal-to-noise ratio; data communication security parameters, such as encryption/decryption codes, keys; data messaging format information; and data transmission protocol information. 85. System according to claim 83, further comprising: means for analysing a detected wireless communication signal at a determined elementary cell or communication zone; and means for determining, on the basis of said analysis, whether a value of a said communication attribute of that signal is appropriate under current wireless communication conditions, said determining means being responsive, if said value of a said communication attribute is determined not to be appropriate, to send a message to said memory to cause the value of said communication attribute to be updated to an appropriate value, or to adjust the value of another communication parameter. 86. System according to claim 85, further comprising means for sending a message directly to the source of said detected wireless signal to cause said source to update the value of said communication attribute to an appropriate value or to adjust the value of another communication parameter. 87. System according claim 83, wherein for at least one communication attribute, said memory stores a plurality of values indexed as a function of at least one of the set: a classification of the wireless communication sending party; a classification of the wireless communication receiving party; a classification of a worksite management attribute to be conveyed in a said worksite management message; a location of the wireless communication sending party; and a location of the wireless communication receiving party. 88. System according to claim 83, adapted to establish or maintain a radio link at a receiving party, said system further comprising: means for accessing at least one stored communication attribute value; and means for automatically configuring receiver means of said receiving party on the basis of a said accessed communication attribute value(s). 89. System according to claim 83, adapted to establish or maintain a radio link at a transmitting party, said system further comprising: means for accessing at least one stored communication attribute value; and means for automatically configuring transmitter means of said transmitting party on the basis of said accessed communication attribute value(s). 90. System according to claim 83, wherein a said communication attribute is a radio frequency or channel allocation, for exchanging data with a remote resource, said system comprising means for automatically updating and using said updated radio frequency or channel allocation as a function of communication conditions. 91. System according claim 83, wherein a said communication attribute is signal strength indicator specifying a modulation or carrier signal strength value to use for a transmission in a communication link, said system further comprising: means for detecting a received signal strength at a receiving party; and means for determining whether said received signal strength is below a threshold and, in the affirmative, for sending a message by the receiving party to correspondingly update said signal strength indicator value in said memory accessible to communicating parties. 92. System according to claim 83, wherein a said communication attribute is a bandwidth capacity parameter expressing the bandwidth capacity limit of a given carrier or channel over a given communication link, said system further comprising: means for determining the current amount of occupied bandwidth of a given communication carrier or channel; and means for comparing said current amount of occupied bandwidth with the bandwidth capacity limit, indicated by said bandwidth capacity parameter, for that given communication carrier or channel, to determine if a determined saturation criterion is reached and, in the affirmative, for sending a message to said memory and/or to communicating parties concerned, requesting to use another carrier or channel. 93. System according to claim 83, further comprising means, aboard mobile apparatus conducting site modifying tasks, adapted to acquire communication attribute and/or worksite management attribute values, and to communicate and/or store said values as said mobile apparatus is conducting site modifying tasks on the worksite. 94. System according to claim 83, further comprising: means for interrogating at least one source of dynamically updatable data on board mobile apparatus active on said worksite, said source being capable of delivering at least one current attribute parameter value for a communication attribute and/or for a worksite management attribute; means for determining the geographical location at which said current value(s) is/are acquired; and means for storing said attribute parameter value(s) acquired at said interrogating step, in association with the cell corresponding to the said determined geographical location, as an updated communication attribute and/or for a worksite management attribute parameter value. 95. System according to claim 94, further comprising means for sending said updated communication attribute and/or a worksite management attribute value to a remote data management resource for dynamically updating said stored data values, said system further comprising: means for forming a message containing said communication attribute and/or a worksite management attribute parameter value(s) and said geographical location data; and means for sending said message to said remote data management resource. 96. System according to claim 83, further comprising: means for interrogating at least one source of dynamically updatable data on board said mobile apparatus, said source being capable of delivering at least one current communication attribute and/or a worksite management attribute parameter value; means for determining the geographical location at which said current value(s) is/are acquired; and means for associating and locally storing said current communication attribute and/or a worksite management attribute parameter value(s) and said geographical location data on board said mobile apparatus. 97. System according to claim 96, further comprising means for uploading said communication attribute and/or a worksite management attribute parameter value(s) and said geographical location data from said mobile apparatus to a remote data management resource at a determined updating moment. 98. System according to claim 83, wherein the value(s) of at least one said communication attribute and/or a worksite management is/are dynamically updatable, said system comprising means, aboard mobile apparatus, for acquiring and communicating attribute data on-the-fly as said mobile apparatus performs worksite modifying tasks and evolves over said worksite area. 99. System according to claim 83, further comprising means for acquiring worksite attribute parameter value(s) comprising at least one of the set: a total station type of surveying device; an aerial view sensor; a GPS (global positioning by satellite) device; and an LPS (local positioning system). 100. System according to claim 83, further comprising: data filtering means for selecting, from the stored attribute values, those items of information relevant to at least one of the set: selected cells; selected site-modifying apparatus; and selected tasks on said worksite; and means for sending said filtered information to targeted recipients.

The present invention relates to the field of worksite management, notably in civil engineering (construction sites, road building, urban development, etc.), landscaping, mining, etc., and aims more particularly at providing a method and apparatus for managing wireless communication of different types of management data that come into play in a worksite project. Worksite projects can be vastly complex and call for a wide variety of information from its initial planning phase to physical completion. To assist in this task, it is known to use computer-aided tools for generating a target land contour for a worksite, based on surveying data of the original contour of the land in question. These tools generate models from which elementary tasks can be e.g. assigned to various items of on-site apparatus, such as earthmoving-apparatus, the latter in some cases being automated to varying degrees. The earthmoving apparatus or its operator needs to be provided at all times with all the necessary information for conducting the task at hand at its location. This information will generally have various possible sources: a central model held at an on-site office, external devices such as beacons, laser guides, onboard sensors, and the like. As the tasks to be performed by an earthmoving apparatus are inextricably linked to its exact physical location, it has become usual practice to provide each item of mobile apparatus with a positioning device such as a GPS receiver and two-way communication links with different stations, or possibly other mobile apparatus on the site. In this connection, patent document U.S. Pat. No. 5,631,658 discloses a system for automatically operating geography-altering machinery in a worksite on the basis of a pre-established three-dimensional model of the target contour relative to an existing contour. The latter is divided into elementary grid elements which can be indexed with the position of a contour-modifying tool of a particular earthmoving apparatus. A computerised system on board of the earthmoving apparatus stores the site plan, identifies the current position and elevation of the contour-modifying tool using a GPS device, and automatically determines the actions to be performed with that tool to make the existing contour at that local level correspond to the target contour. In the field of open-cast mining, patent document U.S. Pat. No. 5,850,341 discloses a system for monitoring the removal of ore with reference to a three-dimensional map of the mine. The map is subdivided into elementary regions which are differentiated according to the type or grade of ore they contain, that information being acquired and recorded at an initial phase. The mobile excavating machinery is provided with a GPS receiver for positioning relative to the map and a sensor for detecting the amounts of ore removed. This information is correlated with the data concerning the ore to control the mobile excavating operations and keep track of the excavated ore. Patent document U.S. Pat. No. 5,935,192 discloses a database technique for identifying and associating information with elementary sections of a worksite. Each section of the worksite is defined by a corresponding data object occupying two dimensions of a layered data organisation. The layers are classed as objects, each associated with a parameter of the worksite. The information is used notably for a differencing algorithm to direct the operations of working machines through an operator display or an automatic controller. Patent document U.S. Pat. No. 5,404,661 discloses a technique for acquiring the three-dimensional position coordinates of a work tool in relation to a stored model of a worksite. The tool position information is obtained through a GPS in cooperation with a dynamically updatable database. Patent document U.S. Pat. No. 6,463,374 discloses a technique for guiding agricultural vehicles, especially for obtaining appropriate spraying patterns over areas of complex contours. The prior art does not address the problem of wireless communications between different entities in a worksite, which calls for specific considerations. Indeed, a worksite can cover a considerable area over which communications conditions can differ from place to place and as a function of time. Also, the communicating entities—which can be mobile or fixed—may have their own communications parameters or characteristics to take into account. By contrast, the invention proposes an approach in which fully takes into account the management of wireless communication parameters in the overall management of data relating to a worksite. More particularly, the invention proposes, according to a first aspect, a method of controlling wireless messaging in a worksite area, in which worksite management messages are received by, or sent from, communicating entities operating within the worksite, comprising the steps of: dividing at least part of the worksite area into elementary cells mapped in correspondence with the topology of the area, or into such cells and determined communication zones, for a given cell or communication zone of the worksite, establishing at least one communication attribute value pertaining to a parameter of wireless communication to or from the given cell or communication zone, for a given cell, establishing at least one worksite management attribute value of the worksite for the given cell, the worksite management attribute value pertaining to a parameter other than a wireless communication parameter, storing, in a memory, values of the worksite management and communication attributes, each stored attribute value being electronically indexed to the elementary cell, or to the communication zone, for which it was determined, forming a worksite management message with an electronically readable content containing at least one worksite management attribute value, accessing the memory to obtain at least one current communication attribute value in respect of a cell or communication zone to or from which the formed management message is to be communicated by a wireless communication, and establishing a wireless communication to or from the cell or communication zone to send or receive the management message on the basis of the current communication attribute value(s) electronically accessed from the memory. The memory can be provided as a common resource whose contents are accessible to communicating parties exchanging worksite management messages. At least one communication attribute can be one of the following attributes: i) a communication frequency or channel allocation, ii) a signal strength indicator, indicating a signal strength to use, iii) a bandwidth capacity indicator, iv) a detected signal-to-noise ratio, v) data communication security parameters, such as encryption/decryption codes, keys, vi) data messaging format information, vii) data transmission protocol information. The method can comprise the step of indexing, in the memory, worksite management attributes and communication attributes to a common elementary cell to which they pertain. The method can further comprise the steps of: analysing a detected wireless communication signal at a determined elementary cell or communication zone, determining, on the basis of the analysis, whether a value of a communication attribute of that signal is appropriate under current wireless communication conditions, if the value of a communication attribute is determined not to be appropriate, sending a message to the memory to cause the value of the communication attribute to be updated to an appropriate value (e.g. to adjust the value of another communication parameter). The method can further comprise sending a message directly to the source of the detected wireless signal to cause the source to update the value of the communication attribute to an appropriate value (e.g. an increased or decreased signal strength) or to adjust the value of another communication parameter (e.g. a carrier frequency or channel allocation). For at least one communication attribute, the memory can store a plurality of values indexed as a function of at least one of: i) a classification of the wireless communication sending party, ii) a classification of the wireless communication receiving party, iii) a classification of a worksite management attribute to be conveyed in a worksite management message, iv) a location of the wireless communication sending party, v) a location of the wireless communication receiving party. The method can comprise the step of establishing or maintaining a radio link at a receiving party, with the sub-steps of: accessing at least one stored communication attribute value, and automatically configuring receiver means of the receiving party on the basis of (an) accessed communication attribute value(s). The method can comprise the step of establishing or maintaining a radio link at a transmitting party, with the sub-steps of: accessing at least one stored communication attribute value, and automatically configuring transmitter means of the transmitting party on the basis of (an) accessed communication attribute value(s). A communication attribute can be a radio frequency or channel allocation, for exchanging data with a remote resource, and the method can comprise the step of automatically updating and using the updated radio frequency or channel allocation as a function of communication conditions. A communication attribute can be signal strength indicator specifying a modulation or carrier signal strength value to use for a transmission in a communication link, and the method can comprise the steps of: detecting a received signal strength at a receiving party, determining whether the received signal strength is below a threshold, in the affirmative, sending a message by the receiving party to correspondingly update the signal strength indicator value in the memory accessible to communicating parties. A communication attribute can be a bandwidth capacity parameter expressing the bandwidth capacity limit of a given carrier or channel over a given communication link, and the method can comprise the steps of: determining the current amount of occupied bandwidth of a given communication carrier or channel, comparing the current amount of occupied bandwidth with the bandwidth capacity limit, indicated by the bandwidth capacity parameter, for that given communication carrier or channel, to determine if a determined saturation criterion is reached, in the affirmative, sending a message to the memory and/or to communicating parties concerned, requesting to use another carrier or channel. The stored worksite and communication attribute parameter values can be organised in a three-dimensional matrix of which the first and second dimensions map the topology of the worksite area and define the locations of the elementary cells or communication zones, and the third dimension corresponds to the set of worksite management and communication attribute parameter(s). An elementary cell can be dimensioned as a function of at least one of: the variation in contour at the cell, the variation in contour at the immediate vicinity of the cell, the rate of variation with respect to position in the value of at least one data to be managed, the type of tool(s) scheduled to operate in the area occupied by the elementary cell. Dimensions of elementary cells can be variable over the worksite area. Communication attribute and/or worksite management attribute values can be acquired and communicated and/or stored by mobile apparatus as they are conducting site modifying tasks on the worksite. The method can comprise the steps of: interrogating at least one source of dynamically updatable data, on board mobile apparatus active on the worksite, capable of delivering at least one current attribute parameter value for a communication attribute and/or for a worksite management attribute, determining the geographical location at which the current value(s) is/are acquired, and storing the attribute parameter value(s) acquired at the interrogating step, in association with the cell or communication zoned corresponding to the determined geographical location, as an updated communication attribute and/or a worksite management attribute parameter value. An updated communication attribute and/or worksite management attribute value can be sent to a remote data management resource for dynamically updating the stored data values by the steps of: forming a message containing the communication attribute and/or a worksite management attribute parameter value(s) and the geographical location data, and sending the message to the remote data management resource. The method can comprise the steps of: interrogating at least one source of dynamically updatable data on board the mobile apparatus, capable of delivering at least one current communication attribute and/or worksite management attribute parameter value, determining the geographical location at which the current value(s) is/are acquired, associating and locally storing the current communication attribute and/or worksite management attribute parameter value(s) and the geographical location data on board the mobile apparatus. The method can further comprise the step of uploading the communication attribute and/or a worksite management attribute parameter value(s) and the geographical location data from the mobile apparatus to a remote data management resource at a determined updating moment. The value(s) of at least one of the communication attribute and/or worksite management attributes can be dynamically updatable, and acquired and communicated on-the-fly by, and as, a mobile apparatus performing worksite modifying tasks evolves over the worksite area. At least one worksite management attribute can relate to physical or chemical material characteristics of the worksite and/or physical or chemical atmospheric characteristics of the worksite. At least one worksite management attribute parameter value can inferred from operating parameters of a site-modifying apparatus operative in the worksite area. At least one worksite management attribute value can be established prior to site modifying operations on the worksite and relate to a non-dynamic land characteristic of the worksite. At least one worksite management attribute value can be established prior to site modifying operations on the worksite and relate to operating characteristics of mobile apparatus. At least one worksite management attribute value can established prior to site modifying operations on the worksite and relates to legal, administrative, or contractual data associated to the worksite. At least one worksite management attribute can relate to a reference level, its value for a cell expressing reference level value with respect to which elevation/depth values are established for that cell. The method can further comprise the step of preparing an individualised dataset specific to an identified site-modifying mobile apparatus, the individualised dataset comprising selected communication attribute and/or a worksite management attribute parameter values for the requirements of that site-modifying mobile apparatus. The individualised dataset can relate only to cells of a region of the worksite where the site-modifying apparatus is programmed to be present over a determined time window. In another aspect, there is proposed method of managing data relating to a worksite area, comprising the steps of: at an initial phase, establishing a set of at least one attribute parameter pertaining to an attribute of the worksite, the attribute parameter having an attribute parameter value susceptible of varying as a function of position in the area, subdividing the area into elementary cells mapped in correspondence with the topology of the area, for at least one the elementary cell, determining the attribute parameter value at that elementary cell of at least one attribute parameter, storing attribute parameter values, each stored attribute parameter value being indexed to the elementary cell for which it was determined, determining evolutions in attribute parameter values, and dynamically updating the stored attribute parameter values on the basis of the determined evolutions. The attribute parameter can express verified data or plausible data concerning an existing state of the worksite. An example of plausible data arises when the attribute parameter relates to a quantity that may have evolved and changed with time, so that it is not verified for the actual existing state of the site. For instance, the attribute data parameter can be the position of a cavity or conduit detected or created in the past, and kept on record. It may then remain plausible that the cavity is still present, but at a slightly different position, or partially filled owing to land movement. Another example is where the parameter was detected/measured with apparatus known to be subject to systematic or random error. The stored attribute parameter values can be organised in a three-dimensional matrix of which the first and second dimensions map the topology of the worksite area and define the locations of the elementary cells, and the third dimension corresponds to the set of attribute parameter(s). An elementary cell can be dimensioned as a function of at least one of: the variation in contour at the cell, the variation in contour at the immediate vicinity of the cell, the rate of variation with respect to position in the value of at least one data to be managed, the type of tool(s) scheduled to operate in the area occupied by the elementary cell. An elementary cell can, moreover, be dimensioned to be smaller than the footprint of a tool scheduled to operate in the area occupied by the elementary cell, whereby an attribute parameter value relevant for the operation of the tool can be obtained with a determined degree of accuracy. Dimensions of elementary cells are variable over the worksite area. An attribute parameter can relate to elementary cell dimensions, expressed by the attribute parameter value(s) of that attribute parameter. A given area can be covered by more than one elementary cell, each having assigned thereto respective and complementary attribute data. This allows to chose optimum elementary cell size as a function to specific attribute data parameters to which they are associated. The cells covering a given point in the area can then be considered to form a whole, equivalent to a single cell covering that point and comprising all the attributes of those multiple cells. Attribute parameter values can acquired and communicated and/or stored by mobile apparatus as they are conducting site modifying tasks on the worksite. The data to be managed can be acquired and communicated and/or stored by mobile apparatus moving on the worksite specifically for acquiring and communicating and/or storing the attribute parameter value(s). The method can comprise the steps of: interrogating at least one source of dynamically updatable data on board the mobile apparatus, capable of delivering at least one current attribute parameter value, determining the geographical location at which the current value(s) is/are acquired, and storing the attribute parameter value(s) acquired at the interrogating step, in association with the cell corresponding to the determined geographical location, as an updated attribute parameter value. The updated parameter value can be sent to a remote data management resource for dynamically updating the stored data values by the steps of: forming a message containing the attribute parameter value(s) and the geographical location data, and sending the message to the remote data management resource. The message forming and sending steps can be performed on board the mobile apparatus. The method can comprise the steps of: interrogating at least one source of dynamically updatable data on board the mobile apparatus, capable of delivering at least one current attribute parameter value, determining the geographical location at which the current value(s) is/are acquired, associating and locally storing the current attribute parameter value(s) and the geographical location data on board the mobile apparatus. The method can further comprise the step of uploading the attribute parameter value(s) and the geographical location data from the mobile apparatus to a remote data management resource at a determined updating moment. The dynamically updatable attribute parameter value(s) can be acquired and communicated on-the-fly as the mobile apparatus evolves over the area. The data to be managed can relate to physical or chemical characteristics of the worksite and/or physical or chemical atmospheric characteristics of the worksite. The data to be managed can comprise at least one of the following types of data for the region occupied by a cell: ground humidity, ambient air humidity, ground temperature, ambient air temperature, ground density, outgassing characteristics, chemical or physical composition data of material, mechanical characteristic data of material, optical characteristics of material, e.g. colour, reflectivity, qualitative information on at least one operation to be carried out, e.g. a cut or fill indication. At least one dynamically updated attribute parameter value can be acquired by a sensor specifically provided for sensing that attribute parameter. At least one dynamically updated attribute parameter value can be inferred from operating parameters of a site-modifying apparatus operative in the worksite area. The attribute parameter value(s) can further comprise at least one attribute parameter value established prior to site modifying operations on the worksite. At least one attribute parameter value established prior to site modifying operations on the worksite can relate to a non-dynamic land characteristic of the worksite. At least one attribute parameter value established prior to site modifying operations on the worksite can comprise at least one of: soil type, land composition at a specified depth or depth range, possible existence of a buried conduit, indication of the type of buried conduit, possible existence of an underground cavity, indication of the type of underground cavity, recorded or supposed position of a buried conduit or underground cavity (e.g. depth, position within cell, etc.). At least one attribute parameter value established prior to site modifying operations on the worksite can relate to operating characteristics of the mobile apparatus. At least one data value established prior to site modifying operations on the worksite can relate to legal, administrative, or contractual data associated to the worksite. The legal, administrative, or contractual data can relate to at least one of: land ownership, insurance coverage, assigned contractor, task cost, task priority, legal status, possible existence of a toxic hazard, indication of archaeological interest. As explained above, an attribute parameter can also be a communications parameter, e.g. radio frequency, for exchanging data with a remote resource. At least one attribute parameter can relate to a reference level, its attribute parameter value for a cell expressing reference level value with respect to which elevation/depth values are established for that cell. The method can further comprise the step of preparing an individualised dataset specific to an identified site-modifying mobile apparatus, the individualised dataset comprising selected attribute parameter values for the requirements of that site-modifying mobile apparatus. The individualised dataset can relate only to cells at, and in the immediate vicinity of, the site-modifying apparatus at a current geographical location of the latter. The individualised dataset can relate only to cells of a region of the worksite where the site-modifying apparatus is programmed to be present over a determined time window. The individualised dataset can relate only to attribute parameter data, among the stored attribute parameter values, which are relevant to the site-modifying apparatus. The attribute parameter values can be centralised at a main database. The attribute parameter values can also be distributed over plural distributed databases. According to another aspect, the invention relates to a system for controlling wireless messaging in a worksite area, in which worksite management messages are received by, or sent from, communicating entities operating within the worksite, at least part of the worksite area being divided into elementary cells mapped in correspondence with the topology of said area or being divided into such cells and determined communication zones, the system comprising: means for establishing, for a given cell or communication zone of the worksite, at least one communication attribute value pertaining to a parameter of wireless communication to or from the given cell or communication zone, means for establishing, for a given elementary cell, at least one worksite management attribute value of the worksite for the given cell, the worksite management attribute value pertaining to a parameter other than a wireless communication parameter, memory means for storing values of the worksite management and communication attributes, each stored attribute value being electronically indexed to the elementary cell, or to the communication zone, for which it was determined, means for forming a worksite management message with an electronically readable content containing at least one worksite management attribute value, means for accessing the memory to obtain at least one current communication attribute value in respect of a cell or communication zone to or from which the formed management message is to be communicated by a wireless communication, and means for establishing a wireless communication to or from the cell or communication zone to send or receive the management message on the basis of the current communication attribute value(s) electronically accessed from the memory. According to a yet another aspect, there is provided an apparatus for managing data relating to a worksite area comprising: means, operative at an initial phase, for establishing a set of at least one attribute parameter pertaining to an attribute of the worksite, the attribute parameter having an attribute parameter value susceptible of varying as a function of position in the area, mapping means storing a set of elementary cells which subdivide the area in correspondence with the topology of the area, means for determining the attribute parameter value at that elementary cell, for at least one attribute parameter, storage means for storing attribute parameter values, each stored attribute parameter value being indexed to the elementary cell for which it is determined, means for determining evolutions in attribute parameter values, and means for dynamically updating the stored attribute parameter values on the basis of the determined evolutions. The optional characteristics presented above in relation to the method according to the first aspects are applicable mutatis mutandis to the above apparatus, and vice versa. The apparatus can further comprise means for acquiring the attribute parameter value(s), the means being at least one of: a total station type of surveying device, an aerial view sensor, a GPS (global positioning by satellite) device, An LPS (local positioning system). The apparatus can further comprise data filtering means for selecting, from the stored attribute parameter values, those items of information relevant to at least one of: selected cells, selected site-modifying apparatus, selected tasks on the worksite, and means for sending the filtered information to targeted recipients. The optional aspects presented in connection with the method according to any of the above aspects can be transposed mutatis mutandis to the above apparatus. According to a further aspect, the invention relates to a data base comprising a single storage unit or distributed storage units, containing attribute parameter values, the attribute parameter values being prepared specifically for the execution of the method according to the first aspect or any other aspect. According to a yet another aspect, the invention relates a storage medium containing an individualised dataset specific to an identified site-modifying mobile apparatus, the individualised dataset being prepared specifically for the execution of the method according to the first aspect or any other aspect, and comprising selected data elements of the attribute parameters for the specific requirements of that site-modifying mobile apparatus. The individualised dataset can relate only to cells at, and in the immediate vicinity of, the site-modifying apparatus at a current geographical location of the latter. The individualised dataset can relate only to cells of a region of the worksite where the contour-modifying apparatus is programmed to be present over a determined time window. The individualised dataset can relate only to a/those attribute parameter value(s) among the set managed data, which is/are relevant to the site-modifying apparatus. According to a further aspect, the invention, the invention relates to a data carrier containing code executable by processor means, to cause the processor means to carry out the method according to the first aspect or any other aspect. According to yet a further aspect, the invention relates to code executable by processor means, the code causing the processor means to carry out the method according to the first aspect or any other aspect. The invention and its advantages shall become more apparent from reading the following description of the preferred embodiments, given surely as non-limiting examples, with reference to the appended drawings in which: FIG. 1 is a diagram showing the initial three-dimensional contour of part of a worksite, illustrating the position coordinates of an elementary cell Cij, taken randomly from the group of elementary cells into which the worksite is decomposed in accordance with an embodiment of the invention; FIG. 2 is a diagram showing the target three-dimensional contour of the same part of the worksite as shown in FIG. 1, illustrating the aforementioned elementary cell Cij with its new position coordinates; FIG. 3 is a diagram illustrating how an elementary cell is dimensioned relative to the size of a contour-modifying tool used on the worksite, according to an embodiment of the invention; FIG. 4 is a schematic representation of a virtual space for containing attribute data referenced to a two-dimensional x-y plane on which the contour of the worksite is mapped; FIGS. 5a and 5b are schematic representations of an elementary cell and its associated attribute data in the virtual space of FIG. 4, in which FIG. 5b is a continuation, starting from the top, of the virtual space interrupted at the bottom of FIG. 5a; FIG. 6 is a block diagram showing the main functional units that manage and exploit attribute data in accordance with a preferred embodiment of the invention; FIG. 7 is a schematic diagram representing part of the worksite divided into communication zones for managing wireless communications, FIG. 8a is a flow chart showing steps in a communications management procedure utilising the communication parameter attributes in accordance with the invention, notably at the level of a receiving party; FIG. 8b is a continuation of the flow chart of FIG. 8b, showing in particular a communications management procedure utilising the communication parameter attributes in accordance with the invention, notably at the level of a transmitting party; FIG. 9 is a symbolic diagram showing a mobile contour-modifying apparatus and selected elementary cells with their attribute data downloaded into an onboard memory of that apparatus as a function of its planned area of operation; FIG. 10 is a block diagram showing the functional units used to produce an individualised attribute data set for a given mobile apparatus, from an attribute database containing a full attribute data set; FIG. 11 is a block diagram showing the functional units used to upload attribute data acquired by onboard sensors in a mobile apparatus to a central attribute data manager in accordance with the preferred embodiment of the invention; FIG. 12 is a block diagram showing a variant in which the full attribute data set is physically stored over a number of distributed attribute databases; and FIG. 13 is a schematic diagram showing how multiple units of mobile apparatus can upload and download attribute data with respect to an attribute data manager in accordance with the preferred embodiment of the invention. Referring to FIG. 1, the initial contours of a worksite 1 are acquired using standard surveying techniques to derive a three-dimensional computer readable map. Positions within the worksite are referenced with respect to a point of origin 0 and identified by three coordinate values along respective orthogonal x, y, z axes designated by reference numeral 2 in the figure. The surface S of the initial contour is subdivided into elementary areas, each corresponding to a cell. The figure shows one such cell Cij whose central point has the coordinates Ixi, Iyj, Izij, where the prefix “I” indicates that these coordinate values correspond to the initial contour of the worksite. The cells can be of uniform size, or they can vary in size over the site. FIG. 2 shows the same portion of the worksite as in FIG. 1 with the contours as they should appear at the conclusion of the earthmoving tasks. This finalised form is hereafter referred to as the “target” contour. In the illustrated example, the section contains a portion of road 3 with raised sides 5a and 5b. The cell Cij of FIG. 1 is shown on this target contour. Being mapped against the same x-y coordinate plane, it retains the same x and y coordinate values Ixi, Iyj, but has a new z coordinate value Tzij, where the letter “T” indicates the target value for that z coordinate. Generally, the x and y coordinate values of any cell (generically designated by the letter C) in the map are invariable between the initial and target contours, while the z coordinate value is likely to differ. The dimensions of the elementary cells along the x and y directions are preferably made smaller than the dimensions of a site-modifying tool used on the worksite, at least for cells assigned to attributes relevant to tool commands. This is illustrated by FIG. 3, which shows a blade 4 of a bulldozer having a width W occupying three contiguous elementary cells Cij, C(i+1)j, C(i+2)j, the latter being partially occupied. This relative sizing of the elementary cells C, allows the contour-modifying tool 4 to be positioned accurately with respect to the digital map represented by the set of elementary cells C. The skilled person can determine the appropriate mesh size (pitch of the cells along the x and/or y directions) of the thus-constituted grid according to the positioning accuracy required and the type of contour-modifying tools likely to be used on the site. It is also not necessary to have identical dimensions for each elementary cell. Also, the latter can be square or rectangular, with an arbitrary length/width ratio. For instance, if the initial contour and target contour of a given portion of the site are such that relatively large contour-modifying tools are expected to be used, then the cell dimensions at that location can be made correspondingly large. Conversely, if finer contour-modifying tools are envisaged for a particular portion of the worksite, or if that portion exhibits pronounced contour variations, then the dimensions of the elementary cells for that portion can be made correspondingly small to achieve the required precision. In conformity with the present invention, each elementary cell C of the worksite is associated with a set of attribute data, generically designated hereafter by the abbreviation AD. An item of attribute data comprises an attribute parameter value or set of values for a specified attribute parameter. As illustrated in FIG. 4, the attribute data AD are contained in an imaginary space referred to as “attribute data space” 6. In the representation used, the attribute data space 6 corresponds to a volume beneath a top layer portion 8 that expresses initial and target contour coordinate values on the x-y plane against which the worksite is mapped (this layer portion 8 shall hereafter be referred to as the “coordinate layer portion”). The AD space 6 effectively defines a three-dimensional matrix, in which two dimensions (x and y dimensions) serve to locate the cells. The attribute parameters are expressed along the third dimension z (vertical). In the representation, each attribute parameter is shown as a respective layer in the AD space 6. The AD parameter values for a given cell are thus the values at the corresponding successive layers along the z direction beneath the x-y coordinates of that cell. Each elementary cell C thereby has an associated column 10 of attribute data values extending from beneath the coordinate layer portion 8. This is shown in the figure for cell Cij, for which the column 10 of AD parameter values is designated ADij. The top surface of the coordinate layer portion 8, hereafter referred to as the “coordinate data layer”, effectively maps the x-y plane of the worksite. This layer portion contains, for each cell: the x and y coordinates of the corresponding cell (e.g. the centre point coordinates, or position of a predetermined corner), and the target z coordinate value (i.e. the elevation at the conclusion of the earth-moving task) of the corresponding cell. Thus, for cell Cij, the coordinate data layer 8 is composed of a field containing a vector of three numerical entries respectively for the x, y, z coordinate values xi, yj and Tzij (the prefix “IT” indicates that the value refers to the target z coordinate value). It may also include the initial z-coordinate value Izij (cf. FIG. 1). There shall now be described the implementation of attribute parameters associated to the cells. An attribute data parameter is expressed by an attribute parameter value, or set of values, hereafter referred to generally as an attribute data value, or AD value. FIGS. 5a and 5b indicate the types of AD values used in the embodiment to constitute a complete attribute data set. Each AD parameter is assigned to a respective layer in the attribute data space 6. In the figures, these layers are represented for an arbitrary column 10 attached to an elementary cell C. Each layer of the column 10 stores one value or a group (vector) of values of attribute data to be associated to that elementary cell, and which quantify or qualify the corresponding type of attribute. For a given cell, a layer can in some cases be left blank, if its attribute parameter is not relevant or its value is not known for that cell. Where the cells have variable dimensions over the worksite area, the dimensions of the cells can themselves constitute a member of the set of attribute data. In the example, the AD parameters fall into two classes: i) wireless communication parameter attributes, which collectively define the data and control settings for establishing and maintaining wireless communications over the worksite and beyond, and which are variable as a function of position and/or time, and ii) worksite management parameter attributes, which include any parameter intervening in connection with worksite task management, excepting the wireless communication parameters of i) above. The above classification of the attribute data parameters is convenient in that it allows to establish or maintain wireless communication information concerning worksite management and their attributes by referring to the values of the corresponding wireless communication attribute parameters of the cell or communication zone concerned. In the embodiment, both the worksite management parameter attributes and the wireless communication parameter attributes are mapped on a common system of cells (or group of cells defining a communication zone, as explained further). This enables notably to store, access and manage the attribute data of both classes seamlessly in a common structure. A communication attribute parameter can for instance be updated and handled using the same data management and database commands as for updating and handling a worksite management attribute. Overall, the attribute data parameters are presented in terms of five different categories: a first category assigned exclusively to the communication parameter attributes (FIG. 5a), and four categories covering the worksite management parameter attributes, the latter being: real-time detected attribute data, pre-surveyed attribute data (FIG. 5a), task attribute data and administrative attribute data (FIG. 5b). Each category of attribute data occupies a number of layers in a respective section of the attribute data space 6, that number corresponding to the number of AD parameters belonging to the category in question. In FIG. 5a, the initial x and y coordinates are designated 8a, and the target z value is designated 8b, these values together forming the coordinate data layer 8. The communication parameter attributes (abbreviation CPAV, section 6a of attribute data space) concern data for establishing and maintaining wireless communication links between communicating entities on and off the worksite, as explained further with reference to FIGS. 8a and 8b. The communication parameter attributes used in the embodiment are: a frequency or channel parameter set C01 for a given wireless communication link, such as a wireless local area network (WLAN), as a function of the location of the receiving and/or transmitting parties, as well as other factors, such as bandwidth occupation, reception conditions, types of communicating entities concerned, etc.; a signal strength indicator parameter set C02, which indicates a signal strength to use for transmission according to range/reception conditions, if needs be as a function of channel/frequency; and a bandwidth capacity parameter set C03, which indicates the bandwidth capacity of a given communication frequency or channel, and optionally a bandwidth saturation threshold limit. This information enables a receiving or transmitting party to determine whether the carrier frequency or channel is close to saturation in terms of its maximum data traffic capacity, so as to switch to a less occupied frequency or channel to avoid a breakdown and to spread the load on the wireless transmission spectrum used. If data communication security provisions are called for, further communication parameters can be stored and managed as above for corresponding parameters in respect of security, privacy, ot integrity protection. For the instance, communication attribute parameters in respect of data communication security can comprise one or any combination of: encryption codes or keys, passwords, logins, etc., parameters for establishing virtual private networks, etc. The communication attributes can also comprise information in connection with messaging formats and communication protocols to use, possibly taking into under different conditions and sending/receiving parties. As for other communication parameters, each of these data communication security parameters can be managed as sets or vectors of values as a function of the type or classification of the communicating entities concerned. The real-time detected AD parameter values (abbreviation RDAV, section of 6b of the attribute data space) generally concern data gathered on the worksite while work is in progress. These data are typically acquired by specific sensors on board mobile apparatus that perform contour-modifying tasks, or by sensors that are provided specifically for data acquisition purposes. In the example, the real time detected attribute values are: material (e.g. soil) humidity (F01), ambient air humidity (F02), material (e.g. soil) temperature (F03), ambient air temperature (F04), soil or ground density (F05), chemical composition data of material (F06), physical composition data of material (F07), mechanical characteristic data of material (F08), optical characteristics of the material, e.g. colour, reflectivity (F09), outgassing rate (F10), and type of gas outgassed (F11). The last two parameters can provide valuable information on the soil characteristics (indicating for instance fermentation if an outgassing of methane is detected), or a possible leak in a fluid conduit. The pre-surveyed AD parameter values (abbreviation PSAV, section 6c of the attribute data space) correspond to information acquired prior to the earthmoving tasks, and which generally indicate characteristics of the worksite on and beneath the surface that are useful to know. In the example, the pre-surveyed attribute data are: soil or ground type (G01), the qualitative land composition according to depth, respectively 0-0.2 metres (G02), 0.2-0.5 metres (G03), and 0.5-1.0 metres (G04) below ground (from the initial contour), to produce cut information, an indication of a buried conduit (GO5) (expressed as a Boolean yes/no), a code indicating the type of buried conduit (G06), an indication of an underground cavity (G07), a code indicating the type of underground cavity (G08), depth data in relation to a buried conduit or underground cavity (G09). Another attribute parameter used in respect of a buried conduit and/or cavity relates to the exact positioning within a cell (G10) and, if needs be, indications of possible positioning errors or drifts (G11). This parameter can thereby express positional precisions or uncertainties. For instance, the last record of a conduit or cavity may date from a time subsequent to which some local land movement may have occurred, or the records may have been based on error-prone techniques. The position data can then accommodate for this situation. It can also indicate the locations of conduit/cavity boundaries e.g. in terms of height/depth, x, y coordinates within the cell (G12). The depth data can be referenced with respect to a universal/local height reference level. This reference level can be marked out by sweeping laser beams, ground markers, etc. In the example, the reference level is also one of the attribute data parameters managed for each cell or group of cells. Typically, this parameter value is a numeral expressing a height (positive or negative) of the reference level with respect to actual ground level at that cell (e.g. at the cell's centre) (G13). This numeral is updated at regular intervals so as to continue to provide the correct reference level indication as the actual ground level of the cell changes, e.g. as a function of cut, dig or fill operations carried out. The soil type parameter value is expressed as a code which uniquely corresponds to one of a set of listed possible soil types, for example clay, fine gravel, earth with chalk, etc. The correspondence between the soil type and the code are stored in a look up table accessible by the entities concerned. The ground composition data can, of course, be extended to cover greater depths as required. The task attribute values (abbreviation TAV, section 6d of the attribute data space) generally correspond to parameter settings for both the end result of the surface and the machinery for producing that result. In the example, the task attribute values are: indications for dig/cut or fill operations (H01), which can be quantitative and/or qualitative, e.g. an extent indicated with respect to the reference level, the required slope of the surface along the x-axis (H02), the required slope of the surface along the y-axis (H03), the top surface finish required (H04), the type of apparatus (H05) and the type of contour-modifying tool (H06) to be used to conduct the task, and servo control settings (H07) for the apparatus actuators. The administrative AD parameter values (abbreviation AAV, section 6e of the attribute data space) correspond to a legal or contractual status associated to the land mapped by the elementary cell concerned. In the example, the administrative attribute values are: the land owner (101), information regarding insurance coverage (102), the contractor responsible for undertaking the contour-modifying tasks (103), information for calculating a charge for the contour-modifying tasks (104), a priority attribution for the tasks (105), the legal status of the land (106) (e.g. whether the land concerned is a nature reserve, council property, private property etc.), an indication of a possible toxic hazard associated to the land (107) (e.g. radioactive waste), and an indication of a possible archaeological interest (108), etc. All these administrative AD parameter values are expressed in terms of pre-established codes corresponding to listed items stored in look up tables and accessible by the entities concerned. Naturally, for any of the above classes of communication or worksite management attribute values, the list of AD parameters is open and can be modified dynamically to suit circumstances. It will be appreciated that the term “value” used in connection with any attribute parameter (attribute data value) encompasses all possible descriptors as appropriate, these being e.g. numerical, verbal, identification codes, Booleans, etc. Each data entry for an attribute data parameter value in any of the above categories corresponds to a value inputted into a pre-formatted computer-readable field. Depending on the nature of the attribute data concerned, the entered value can be in the form of: a number, an alpha numerical code value, a Boolean (e.g. yes/no), text, etc. These attribute data values thereby form a set of metadata indexed to a specific cell C. It will be understood that the attribute data space 6 effectively constitutes a three-dimensional matrix of values, with two of its orthogonal dimensions defining a coordinate plane for locating each cell in direct correspondence with the x-y physical position of those cells. The third, z, dimension (along the height axis of the columns 10) serves to define the different types of communication and worksite management attribute data values to be associated with each cell. FIG. 6 shows in block diagram form how the aforementioned attribute data are managed and exploited during site-modifying tasks on the worksite 12. The management of the attribute data is allocated to an on-site office 14 at which are located the worksite's main intelligence and communications equipment. The activities of the on-site office 14 are centralised at a central management unit 16 which contains the main computer resources. Tasks which are specific to attribute data are decentralised at an attribute data manager unit 18 which is directly associated to an attribute database 20. This database stores dynamically the AD parameter values in the above-mentioned communication and worksite management attribute data space 6. Generally, when the term “attribute” is used in the description without the qualifier “communication” or “worksite management”, it is intended to cover generically either or both of communication and worksite management attributes, as applicable. The central management unit 16 also cooperates with: a mobile apparatus displacement manager 21 which: keeps track in real-time of the positions of each item of mobile apparatus on the worksite 12, determines the area to be worked in by the remotely guided mobile apparatus as a function of high-level commands received through the central management unit 16, and generally regulates the traffic throughout the worksite to avoid collisions and congestions; an on-site communications manager 22 which handles high and low level tasks in connection with communications (message formatting, addresses, transmission protocols, frequencies, routing, etc.) for all the communicating entities on the site, whether it be between the communicating entities and the on-site office, or between the communicating entities themselves. To this end, the on-site communications manager 22 is associated to a communications interface 24 which contains the baseband and radio layers for wireless communication via an antenna 26 with the on-site communicating entities. It also: manages the read and write operations of the attribute database 20 as regards the communication parameter attributes, ensuring that these are updated as and when required; and communicates the updated communication attributes to all entities on and off the worksite concerned. As explained further, decisions to update some of the communication attributes, e.g. for new frequencies or signal strengths to use, etc., can come directly from entities on the field. The communications manager 22 receives this update data through messages sent by those entities, and acts by entering the updated data into the appropriate fields of the attribute database 20; and an off-site communications interface unit 28 which centralises all communications between the worksite and its outside environment using a number of different communication channels: installed telephone lines, radiolink via an antenna 30, and the Internet 32. In the illustrated example, the off-site communications interface 28 uses the Internet to communicate with off-site offices 34. The off-site and on-site offices can thereby exchange data virtually in real time, e.g. for transferring commands, interrogating and updating databases, sharing computational tasks etc. Security measures such a virtual private network (VPN) tunnelling can be implemented as appropriate. The hardware implementation of the on-site office 14 to acquire, process and store the attribute data can be based on standard processor, memory and communications techniques. The figure shows a bulldozer 36 as an example of a mobile apparatus which exploits attribute data in accordance with the invention. To this end, the bulldozer is equipped with onboard hardware and software (generally designated by reference 38) for communicating with the on-site office 14 and managing the attribute data at its local level. As will be explained in more detail further, the bulldozer 36 is provided with an individualised attribute data set that is limited to its specific requirements at a current time as concerns both its geographical location and the type of attribute data it specifically requires. The onboard hardware and software 38 relevant for exploiting the attribute data comprise: an onboard central processing unit (CPU) 40 which centralises all the functional units of the bulldozer 36, associated with internal and external memories including a random access memory (RAM) 42 in which the local AD parameter values are stored; a global positioning by satellite (GPS) unit 44 associated with a satellite antenna 46 for acquiring the bulldozer's real-time position, speed and direction data. The GPS unit is pre-calibrated with a positional offset so that the positional coordinates acquired correspond to a fixed reference at the level of the contour-modifying tool used (in this case the blade 4). In the figure, the reference is a point RP located at the bottom of the blade 4, centrally along the width dimension of the latter. The reference position is established for a predetermined deployment configuration of the hydraulic rams operating the blade, for instance corresponding to the level where the blade makes contact with the ground when the bulldozer is on a level surface. Positional changes of the reference point caused by movements of the ram (i.e. displacement of the blade relative to the bulldozer itself) can be taken into account from the hydraulic ram command data, so that the absolute position of the reference point RP can be determined all times to within the positional accuracy provided by the GPS system; a cell locator unit 48 cooperating with the GPS units 44 to identify the specific cell C of the mapped worksite at which the reference point RP is located. The correspondence between GPS coordinates and mapped cells is performed by standard techniques e.g. based on look-up tables or algorithms; a servo control unit 50 for controlling the motion of the blade 4 in response to received contour-modifying commands. This unit also sends the required relative blade position data to allow the GPS unit 44 to determine the appropriate offset, as explained above; a sensor management unit 52 which interfaces with all the different sensors that equip the bulldozer. Among these sensors are those which provide at least some of the communication and real-time detected attribute values (sections 6a and 6b of the attribute data space 6). Sensors on board the bulldozer 36 for providing real-time detected attribute values are in this example: an ambient air humidity sensor 54, a soil temperature sensor 56, a soil humidity sensor 58 and an outgassing rate sensor 60. Other types of sensors can be provided as required. Note that the bulldozer also delivers ground density attribute data, which it acquires indirectly from hydraulic pressure and ram response data at the level of the servo management unit 52; a local attribute data manager 62 cooperating directly with the onboard CPU 40 and specifically assigned the tasks relative to the handling, distributing and updating of attribute data at local level. The items of attribute data for current or imminent use are formatted in that unit and stored in the RAM 42 of the onboard CPU; and an onboard communications interface unit 64 which manages all exchanges of data with the outside environment on the basis of the appropriate and current communication attribute parameters C01 to C03, notably with other mobile apparatus and with the on-site office, through the wireless local area network (WLAN) using an antenna 66. The communications attribute parameters serve to optimise data exchanges, notably the over wireless connections described above. Typically, they can be a function of location-dependent factors and/or time-dependent factors, and/or usage-dependent factors. In the embodiment, the communications attribute used are: the radio frequency, corresponding to a channel, to use for communicating from or to the cell C in question. This may be expressed as a list of frequencies where each item corresponds to a type of apparatus or vehicle concerned; the signal strength to use for communicating from or to a particular cell or group of cells forming a communication zone, as explained further. For transmission from the cell C, this may be expressed as a table indicating the signal strength to use for different distances or locations to reach; and the bandwidth occupation for different frequencies or channels at the cell C or communication zone considered. If needs be, the communication attribute can also comprise a signal-to-noise (SNR) indicator and one or a number of data security parameters (codes, keys, etc.) as mentioned above. All of these communication attributes are dynamic and updatable, being a function not only of geographical position, but also susceptible of varying in time as a function of current and evolving conditions, such as: the temporary presence of structures susceptible of causing radio interference, the instant density and type of radio communicating devices in the vicinity of the cell(s) considered, atmospheric conditions, the local and current data security requirements, etc. At any time, a communications attribute can be changed or updated at the level of a cell or a group of cells, the latter typically occupying an area where communications conditions are considered, to all intents and purposes, to be substantially uniform. FIG. 7 illustrates a portion of the worksite which encompasses three communication zones CZn−1, CZn and CZn+1. Each communication zone (generically designated CZ) has a contour surrounding a group of elementary cells C, for which the communications attributes are considered to be common. In the case of communication zone CZn, three variable communication attribute values—or sets of values—are specified as follows: SAn for the signal strength (dB) to use for transmission, Fn for the transmission frequency or channel, and BWOn for the bandwidth occupation, where the subscript n identifies communication zone CZn. Each of those attributes—and possibly data security communication attributes—takes the form of a vector whose components specify respective values for each sub-range or slice of the communication parameter considered. For the signal strength attribute, the vector SAn is a set of k values SA1n to SAkn, each specifying a signal strength value to use for a specified receiving point on or off the site, and/or a specific type of apparatus which is to receive the signal. For each frequency/channel attribute, the vector Fn is a set of p transmit and/or receive frequencies or channels, F1n to Fpn, each corresponding to a carrier frequency to use as a function of: the class of transmitting apparatus (moving vehicle, ground sensor unit, etc.), the class of receiving apparatus, and if needs be the communication zone where the receiving point(s) is/are located. For each bandwidth capacity attribute, the vector BWOn is a set of q values, each corresponding to the limit of signal traffic at a respective communication channel active in communication zone CZn. A BWOn value can express the current (absolute) capacity and a saturation limit directly. The latter can be expressed in terms of a percentage of, or ratio to, the absolute data traffic capacity of carrier frequency/channel in question. Typically, where wireless communication links are established according to a time sharing/division technique, e.g. by time slot allocation, the BWOn value can be expressed in terms of the total number or density of time slots utilised, or by the number of free time slots. The values stored in the database 20 each of the three vectors SAn, Fn and BWOn are updated and evolve in real time as required. The block diagram of FIGS. 8a and 8b illustrates an example in which an item of roving apparatus not only uses the communication attributes to establish and maintain its communications links, but also cooperates in making their values evolve to adapt to and suit instant communication conditions. Starting with FIG. 8a, a roving apparatus periodically checks whether it has entered a new communication zone (step S10) or the expiry of a predefined count-down time setting an interval for re-assessment of a communication attribute parameter. The new communication zone can be identified directly on the basis of the cell(s) in which the apparatus is present, the database recording the cells forming each communication zone. Alternatively, the different communication zones can be marked out by beacons, laser lines, or other detectable boundaries to which the roving apparatus is receptive. In this way, the roving apparatus knows at all times in which communication zone it is present during its displacement. In the example, the apparatus happens to be in communication zone CZn. For each communication event, the apparatus enters a communication mode (step S12), which is divided into a reception (Rx) mode and a transmission (Tx) mode (steps S14 and S16 respectively). In reception mode, the apparatus' radio receiver automatically scans a set of communications channels to detect incoming signals. To this end, it initially determines the sources that can potentially send data to its onboard equipment, i.e. the possible transmission sources (step S18). For each of those sources, it refers to its onboard memory or consults the external database 20 to look up the current value of the transmission channel used by that source (step S20). The channel can additionally be specified for the type of receiving apparatus and for the communication zone in which that receiving apparatus is located. The procedure of steps S18 and S20 is optional, but helps to narrow down the number channels to scan. In a variant, the procedure can skip steps S18 and S20 and systematically scan all channels used on and off the worksite for communicating to/from the roving apparatus in question. When a communication is to be established with an identified sending part, and involves a specific form of data security, messaging format, or data transmission protocol, the receiving party accesses the corresponding communication attribute parameters accordingly, so as to adjust to the appropriate receive/decoding parameters. During reception, the apparatus's radio receiver assesses the signal strength SAn of a received signal against a lower limit threshold LoLimSAn (step S22). If the signal strength (modulation or carrier) does not exceed the prescribed threshold LoLimSAn, then the apparatus' radio sends a message requesting the signal strength to be increased (step S23), notably for the communication attribute entry indexed to the current communication zone CZn as the receiving zone. The request can simply be a command to raise the level by a determined unit quantity, or it can further include an indication of the amount of increase of signal strength. The message is relayed in real time both to the database 20 and to the radio currently transmitting to the apparatus' radio receiver. Accordingly, the currently transmitting radio can instantly raise its signal strength as required. Should this not be sufficient, a channel change or another suited action such as the introduction of a relaying device can be requested (not indicated in the flow chart). The received signal strength SAn is also compared to an upper limit threshold HiLimSAn (step S24). If the assessed signal strength is above that threshold, then the apparatus' radio sends a message requesting the signal strength to be decreased (step S25), notably for the communication attribute entry indexed to the current communication zone CZn as the receiving zone. The request can simply be a command to decrease the level by a determined unit quantity, or it can further include an indication of the amount of decrease of signal strength. The message is relayed in real time both to the database 20 and to the radio currently transmitting to the apparatus' radio receiver. Steps S22 to S25 can be performed during scanning of the frequency channels, where the carrier frequency of each channel is compared for signal strength against a common or respective threshold. In this way, many updates of SAn can be made, covering scanned carrier frequencies/channels not directly concerned by the apparatus. Alternatively, it can be performed just for the active communication channel over which data is received, after the scanning. In the latter case, the signal strength can be the modulation of the information-carrying signal instead or in addition to the carrier signal strength. Any other communicating apparatus can refer to the updated signal strength indicator parameter, for the boundary conditions concerned, to ensure optimum signal strength. In particular, these measures ensure that the signal strengths can be kept to reasonable values, and thus minimise electromagnetic pollution and save on transmission energy. A similar procedure can be applied for a signal-to-noise ratio of the signal, either in addition to or instead of the procedure for the signal strength. If the signal-to-noise ratio (SNR) is considered, the analogue to step S22 would be to consider whether the current detected SNR is above a limit threshold. If it is below that SNR threshold, then the procedure can entail sending a message to increase the signal strength, as for step S23, or to switch to another carrier or channel. Proceeding from step S23 or S25, as the case may be, the apparatus' radio receiver determines the amount of free bandwidth for the channel currently used for the communication. This parameter is based on the maximum bandwidth that can be supported by a communication link, in this case the carrier or channel, and effectively indicates the proportion of that maximum bandwidth used by all resources active in the reception area. The bandwidth occupation can be measured using standard techniques, e.g. from the multiplex utilisation parameters or the signal spectrum. In the example, the bandwidth occupation in question is considered for the receiving communication zone CZn, the bandwidth occupation at the transmitting communication zone being determined independently by the transmitting apparatus. If the bandwidth occupation is equal to or exceeds a predetermined min saturation threshold LimBWOn provided by the bandwidth communication attribute (step S26), then the receiving apparatus' radio sends a message requesting a change of transmission channel and an update of the frequency channel to a new, less occupied, channel (step S28). As for the signal strength update, this request is relayed in real time both to the database 20 and to the radio transmitting currently to the apparatus radio receiver. The currently transmitting radio can instantly change channel to an agreed new channel. Any other communicating apparatus can refer to the updated channel information for future transmissions, under corresponding boundary conditions, until a new update is produced. The receiving apparatus constantly monitors the signal reception to detect the normal ending of a communication and the onset of a new communication (step S30). When a new signal communication is to be started, the procedure loops back to the initial communication mode (step S12) to start again for that new communication. If that new communication is in the receive mode, the procedure described is thereby repeated. The procedure performed by the apparatus' radio for case of a signal transmission (Tx) mode from the latter is indicated by the portion of the flow chart produced in FIG. 8b (cf. encircled A bridging FIGS. 8a and 8b). For a signal transmission, the apparatus in communication zone CZn (in this case the transmitting apparatus) first determines the receiving party/parties (also referred to as the recipient(s)) for communication (step S32). For each identified recipient, it accesses the database 20 to determine that recipient's current location in terms of the corresponding communication zone CZ where it is located (step S34). In the example, the latter is designated communication zone CZr. Next, the transmitting apparatus accesses a look up table in the database 20, or within its memory, containing the frequency parameters, to determine the current communication channel to use for communicating with the selected (receiving) apparatus at communication zone CZr (step S36). Then, it looks up, from the same data source, the current signal strength value to use for communicating to the receiving apparatus (step S38). Note that the channel and signal strength values can be set as result of steps S22 and S23 (signal strength too low) or of steps S24 and S25 (signal strength too high), or of step S26 (bandwidth saturation condition) from an earlier communication link. If needs be, it can look up the required data security codes and other information among the corresponding communication attributes provided to this effect, for the specifics of the communication to be established (characteristics of the receiving parties, type of information to be transmitted, etc.). Likewise, when a communication involves a specific form of data security, messaging format, or data transmission protocol, the receiving party accesses the corresponding communication attribute parameters accordingly, so as to adjust to the appropriate receive/decoding parameters. The transmission is then effected at the frequency (channel) and signal level currently given by the look-up tables (step S40). At regular intervals, the transmitting apparatus checks the bandwidth occupation of the channel currently used, notably to ascertain that it is within the maximum threshold value LimBWOn (step S42), as explained above for the receiving mode (cf. step S26). If the detected bandwidth occupation for the current channel exceeds that threshold, e.g. owing to relatively large number of transmissions locally already sharing that channel, then the transmitting apparatus chooses a new channel (step S44), sends a message signalling a change of transmission channel, specifying the new channel, to each receiving party (step S46). The message is also sent in real time to the database 20, which updates the channel vector accordingly (step S48). After that last step, the procedure loops back to step S38, where it looks up the signal strength to use for that new transmission frequency. All the while the bandwidth occupation remains within the limit LimBWOn (step S42), the communications continue on that channel. At regular time intervals fixed by a time delay (step S50), the transmitting party checks whether it is still actively transmitting (step S52). In the affirmative, the procedure loops back to step S38 mentioned above to determine whether it should adjust the transmission signal strength/carrier frequency or channel to a new value entered in the database 20. Note that signal strength can also be updated by a direct request from a receiving apparatus, as explained in connection with steps S24a and S24b. If at step S52 it is determined that the transmission is no longer active, the procedure is ended. Other communication parameters can be monitored and updated in this way to ensure an optimum use of radio resources and an efficient exchange of communication attributes. Attribute tables can be exchanged via servers to assure consistency. There shall now be explained by way of an example based on the bulldozer of FIG. 9, how the different attributes discussed above can be used for a specific task. In operation, the bulldozer 36 initially receives instructions for working in a specific area. These instructions are downloaded from the mobile apparatus displacement manager 21 using the wireless local area network, and using the transmission and reception procedures discussed with reference to FIGS. 8a and 8b. The mobile apparatus displacement manager also uses the issued information to determine the bulldozer's area of operation on the worksite for a determined time window in view of preparing an adapted individualised attribute data set. This information on the area of operation is sent via the central management unit 16 to the attribute data manager 18. In response, the latter prepares the individualised attribute data set, the individualisation taking into account: i) the area of present and future operations, ii) the specific characteristics of the bulldozer and iii) the tasks planned for the bulldozer in that area. In the above example of the bulldozer (cf. FIG. 6), the site-working tool is more specifically a contour-modifying tool, inasmuch at it changes the height the surface. Some site-modifying tools useable with the present attribute data management method can operate on the site without changing the contour, the tool being e.g. a water sprinkler, a ground marking device, etc. FIG. 9 illustrates an example of the area of operation 68 for the bulldozer 36 for a given time window, calculated on the basis of a current position of the bulldozer and its scheduled area, as determined by the mobile apparatus displacement manager 21. In order to economise on transmission bandwidth and on onboard memory space, only the cells C which cover the area of operation 68 are downloaded into the RAM 42 of the bulldozer 36. For those cells, only the attribute data likely to be required by the bulldozer are incorporated in the individualised attribute data set, again to save on bandwidth and local memory space. Thus, the reduction of information in creating an individualised attribute data set operates on two levels: the topology of the cells (selection of only the pertinent cells) and the types of attribute data (selection of only the pertinent attribute data parameters), corresponding respectively to the x-y plane and the depth dimension of the attribute data space 6 (cf. FIG. 4). The aforementioned time window can be set as a function of one or several parameters among: the capacity of the RAM (a larger time window implies more data to cover more cells), the average speed of displacement, data traffic on the WLAN, etc. FIG. 10 shows the functional units involved in preparing an individualised attribute data set 70. The attribute data manager 18 is initially programmed with a table listing all mobile apparatuses of the worksite susceptible of exploiting attribute data. For each mobile apparatus, the selected attribute data parameters which it needs to carry on board are recorded. The mobile apparatus displacement manager 21 delivers to the attribute data manager 18 the area data MP covering a determined time window for a designated mobile apparatus. In response, the attribute data manager 18 determines the appropriate cells that adequately cover the corresponding area of operation 68 (cf. FIG. 9). By referring to the above table, it then accesses the attribute database 20 to extract, for each of those cells, the selected AD parameters that are relevant to the mobile apparatus concerned. These selected items of attribute data are arranged and formatted to be readable by the onboard CPU 40, and are mapped in accordance with the topology of the cells which constitute the area of operation 68. The individualised attribute data set 70 thereby comprises selected cells SC and values of selected AD parameters SP. Note that as the pertinent AD parameters can be variable for a given mobile apparatus depending on the tasks to be conducted and the characteristics of the ground, the selected AD parameters used can be different for different cells. The thus-compiled individualised attribute data set 70 is incorporated into the user data section of a message according to a predefined protocol and sent to the mobile apparatus by the wireless local area network. Upon receipt by the onboard communications interface 64, the individualised attribute data set 70 is extracted and stored in the onboard RAM 42. The storage is preferably managed according to a memory map following the topology of the area of operation 68. The AD parameter values can then be organised as a z dimension, according to a three-dimensional matrix that corresponds to a section of the attribute data space 6 (cf. FIG. 4), for the AD parameter values present in the individualised data set. The cell locator unit 48 indicates to the other units the cells at the location and in the immediate vicinity of the blade 4. The attribute data associated to those cells are loaded into the local attribute data manager 62, from which they can be accessed (instead of from the RAM 42) during the execution of the different tasks performed by the mobile apparatus. In the above, the attribute data are downloaded from the on-site office to the mobile apparatus. There shall now be explained with reference to FIG. 11 how attribute data acquired at a local level by a mobile apparatus can be uploaded to the on-site office 14 for updating the attribute database 20. The figure shows the sensor management unit 52 controlling N different sensors numbered S1 to SN. Among these sensors are some whose acquired data correspond to attribute data AD parameters managed by the attribute data manager 18. If these sensors happen to be, say, sensors numbered 1, 3, 4, 8 and 11 and acquire AD parameter values SD1, SD3, SD4, SD8 and SD11 respectively, then the local attribute data manager 62 will periodically interrogate these sensors and order the uploading of both their data values, and the spatial coordinates at which they were acquired. This information is then uploaded to the on-site attribute data manager 18 through the wireless area network. The on-site attribute data manager identifies these AD parameter values and the AD parameters to which they apply, and enters those values in the field addresses of the corresponding cells of its attribute database 20. These addresses are defined in terms of the cells corresponding to the spatial coordinates and corresponding AD parameters. The interrogation can be conducted at the initiative of the local attribute data manager 62, or in response to a request from either the on-site attribute data manager 18 or another mobile or static unit on the worksite. In this manner, the attribute database 20 is continuously updated for the fields whose attribute data are susceptible of evolving in the course of the tasks being conducted. The attribute database 20 can also be managed to maintain a history of all attributes and their successive changes/updates as work progresses on the site. This history can serve e.g. to mitigate measurement errors and allow for plausibility checks. It can also provide a source for determining the rate of progress, work efficiency, future improvements in contour modifying procedures or tools, traceability, etc. FIG. 12 shows a variant of the above embodiment which differs by the fact that the entire data set forming the AD parameter values is contained in distributed databases 20a-20d, as opposed to a single storage entity. The overall operation remains the same, the attribute data manager 18 maintaining a table identifying, for each type of the AD parameters, the specific attribute database where that data is stored. In this manner, the attribute data manager 18 can operate seamlessly with the different databases for entering updated data, preparing individualised attribute data sets 70, etc. In the illustrated example, the attribute data manager 18 operates with four separate AD parameter databases, identified by respective Roman numerals I-IV. Databases I and II are physically located off-site and are accessible by the attribute data manager 18 through an online server via the Internet 32. This could be the case, for example, if these databases respectively store the pre-surveyed attribute values and the administrative attribute values. Databases III and IV are both located on-site, but are physically separate units. Database III is connected to the attribute data manager 18 via a wire link 72 and is used, for example, to store the task attribute values. Database IV is connected to the attribute data manager by a radio link over the wireless local area network and is used, for example, to store the real-time detected attribute values. With its wireless connection, this database can itself be managed as a mobile unit installed at variable locations on the worksite for optimum communication over the wireless local area network. In this manner, database IV can be conferred with the additional function of serving as a relay and/or communications hub in the local area network. FIG. 13 is a simplified diagram showing multiple items of mobile apparatus MA1-MA4 on the worksite communicating with the attribute data manager 18. The latter is informed in real-time by the mobile apparatus displacement manager 21 (cf. FIG. 6) of the current position (respectively P1-P4) of each mobile apparatus and, where applicable, the programmed area for the latter (respectively PA1-PA3). Note that a mobile apparatus need not necessarily have a programmed area. For instance, the item of mobile apparatus designated MA4 in the figure is a portable sensor unit carried by a human operator, who is given the initiative of his displacement over the worksite. This can be the case for example where the portable sensor unit is a gas detector which analyses chemical characteristics of outgassing emissions. The sensor unit can identify a gas composition, label it using a predetermined code and send at its initiative a message containing the gas composition code and the position coordinates of its point of detection. The latter are determined through a portable GPS unit carried by the operator, or by a total station used in the field of land surveying. The message is sent over the wireless local area network to the attribute data manager 18, where the code is read and entered as the attribute value in the field corresponding to “gas type” (cf. FIG. 5a) for the cell corresponding to that position, as expressed in the message. The attribute data manager 18 thereby receives and transmits multiple messages from and to the different mobile units, respectively for updating its complete set of attribute data and for downloading to those units the individualised attribute data they currently require, as explained above. In the example, the updated attribute values sent to the attribute data manager 18 are initially buffered, pre-processed and formatted into an update data message ADU sent to the attribute database 20 at short intervals. It will be understood that the attribute data constitute information that is complementary to the data of the three-dimensional models of the initial and/or target contours. If these models use a grid system to define elementary unit areas with respect to a coordinate system, then it is advantageous to use the same grid system to define the cells C of the attribute data space (cf. FIG. 4). In other words, the elementary unit areas of the three-dimensional model and the cells C can be topologically positioned with a common mesh. The acquisition of attribute data can be effected using all types of devices and techniques, which can yield the corresponding data value either directly, or by inference. For instance, besides being acquired by the different sensors mentioned in the examples, the attribute data can also be obtained by: total stations, i.e. surveying apparatus that determine range and elevation data, aerial sensors, aerial photography, where techniques such a photograph miscolour analysis, etc. can be used, local positioning systems (LPS), etc. In some instances, some filtering of the information may be required to select from the complete set of different gathered data only those that are pertinent to a given recipient for transfer to the latter. The filtering criteria can take into account: the part of the site concerned, so that some types of data not necessary for a given portion (identified in terms of cells) can be filtered out, and/or the type of apparatus (site modifying tool, personnel, etc.) concerned. The data filtering means can be positioned at the central office or delocalised to various levels of the worksite, down to the mobile site-modifying apparatus itself. The attribute data can, of course, differ in terms of type, category, number of items covered and formats attributed to its values, according to applications, the embodiment described simply being given as an example. The management and storage of the attribute data can be implemented using a variety of hardware and software techniques. The presentation of the attribute data in accordance with the preferred embodiment, based on a three-dimensional attribute data space mapped against a topology of the worksite, is particularly well suited to some three-dimensional spreadsheet programs. Such spreadsheets are conceptually designed to present a depth dimension to a two-dimensional array of cells. In this case, the two-dimensional cell array can be made to correspond to the x-y coordinate plane on which the worksite is mapped, while the depth dimension is reserved for inserting corresponding attribute data parameter values. The depth of the spreadsheet, expressed in unit storage cells, can thereby be made to accommodate a corresponding depth of attribute data fields. While preferred embodiments have been described, it shall be clear to a person skilled in the art that the invention can be implemented in many other ways as regards hardware, software, choices and classifications of attribute data parameters, etc. while remaining in the scope and spirit of the claims.

20070618

20111004

20071122

87733.0

H04Q700

WYCHE, MYRON

METHOD AND APPARATUS OF MANAGING WIRELESS COMMUNICATION IN A WORKSITE

UNDISCOUNTED

ACCEPTED

H04Q

ACCEPTED

Wireless Multi-Path Transmission System (Mimo) With Controlled Repeaters in Each Signal Path

Methods for exchanging signals via a network with nodes (11-15) improve the performance of the network by letting a destination node (12) s receive the signals originating from a source node (11) via different first and second signal routes, and by processing and correlating these signals in the destination node (12). In dependence of a correlation result, a process for processing a signal in a node (11-15) is adjusted. This process may be situated in the destination node (12), or in the source node (11) or an io intermediate node (13-15), in which case a control signal is to be exchanged. A learning algorithm for the adjusting of the process can be run in the nodes (11-15). Label switched routing can be introduced, whereby the label signal is sent from the source node (11) to the destination node via a third signal route different from the first and second signal route, to improve the efficiency of the nodes (11-15).

1. Method for exchanging signals via nodes (11-14) and comprising the steps of at a source node (11), processing a source signal (21,22) and transmitting the source signal (21,22) to a destination node (12) via a first signal route comprising an intermediate node (13,14) and via a different second signal route, with at least one signal route being a wireless signal route; at the destination node (12), receiving a first destination signal (31) corresponding with the source signal (21,22) and having followed the first signal route; at the destination node (12), receiving a second destination signal (32) corresponding with the source signal (21,22) and having followed the second signal route; at the destination node (12), processing and correlating the first and second destination signal (31,32); and in dependence of a correlation result, adjusting a process for processing a signal at a node (11-14). 2. Method according to claim 1, wherein the process comprises the processing at the destination node (12). 3. Method according to claim 1, further comprising the step of at the destination node (12), transmitting, in response to the correlation result, a control signal to the source node (11) for the adjusting of the process; wherein the process comprises the processing at the source node (11). 4. Method according to claim 1, further comprising the steps of at the intermediate node (13,14), receiving an intermediate signal (41,51) corresponding with the source signal (21,22); at the intermediate node (13,14), processing the intermediate signal (41,51); and at the destination node (12), transmitting, in response to the correlation result, a control signal to the intermediate node (13,14) for the adjusting of the process; wherein the process comprises the processing at the intermediate node (13,14). 5. Method according to claim 1, further comprising the step of at a node (11-14), running a learning algorithm for the adjusting of the process. 6. Method according to claim 1, further comprising the steps of at the source node (11), generating a label signal for labelling the source signal (21,22) and transmitting the label signal to the destination node (12) via a third signal route different from the first and second signal route; and at the destination node (12), detecting the label signal. 7. Method according to claim 1, further comprising the steps of at the destination node (12), further processing at least two subsignals of at least one destination signal (31,32), which subsignals have followed subroutes of at least one signal route, with these subroutes being different from each other. 8. Destination node (12) comprising a receiving unit (91-95) for receiving a first destination signal (31) corresponding with a source signal (21,22) and having followed a first signal route comprising an intermediate node (13,14) and for receiving a second destination signal (32) corresponding with the source signal (21,22) and having followed a different second signal route, which source signal (21,22) has been processed and transmitted by a source node (11), and with at least one signal route being a wireless signal route; a processing unit (87) for processing the first and second destination signal (31,32); a correlating unit (89) for correlating the first and second destination signal (31,32) for, in dependence of a correlation result, adjusting a process for processing a signal at a node (11-14). 9. Destination node (12) according to claim 8, wherein the process comprises the processing by the processing unit (87) at the destination node (12). 10. Source node (11) comprising a processing unit (87) for processing a source signal (21,22); a transmitting unit (91-95) for transmitting the source signal (21,22) to a destination node (12); and a receiving unit (91-95) for receiving a control signal from the destination node (12) for adjusting the processing unit (87); which destination node (12) is arranged to receive a first destination signal (31) corresponding with the source signal (21,22) and having followed a first signal route comprising an intermediate node (13,14) and is arranged to receive a second destination signal (32) corresponding with the source signal (21,22) and having followed a different second signal route, with at least one signal route being a wireless signal route, and which destination node (12) is arranged to process the first and second destination signal (31,32) and is arranged to correlate the first and second destination signal (31,32) and is arranged to, in response to a correlation result, transmit the control signal to the source node (11). 11. Intermediate node (13,14) comprising a processing unit (87) for processing an intermediate signal (41,51); and a receiving unit (91-95) for receiving the intermediate signal (41,51) corresponding with a source signal (21,22) transmitted by a source node (11) to a destination node (12) and for receiving a control signal from the destination node (12) for adjusting the processing unit (87); which destination node (12) is arranged to receive a first destination signal (31) corresponding with the source signal (21,22) and having followed a first signal route comprising the intermediate node (13,14) and is arranged to receive a second destination signal (32) corresponding with the source signal (21,22) and having followed a different second signal route, with at least one signal route being a wireless signal route, and which destination node (12) is arranged to process the first and second destination signal (31,32) and is arranged to correlate the first and second destination signal (31,32) and is arranged to, in response to a correlation result, transmit the control signal to the intermediate node (13,14). 12. Network which comprises one or more destination nodes (12) as defined by claim 8. 13. Circuit (90) for use in a destination node (12) comprising a receiving unit (91-95) for receiving a first destination signal (31) corresponding with a source signal (21,22) and having followed a first signal route comprising an intermediate node (13,14) and for receiving a second destination signal (32) corresponding with the source signal (21,22) and having followed a different second signal route, which source signal (21,22) has been processed and transmitted by a source node (11), and with at least one signal route being a wireless signal route, which circuit (90) comprises a processing unit (87) for processing the first and second destination signal (31,32); a correlating unit (89) for correlating the first and second destination signal (31,32) for, in dependence of a correlation result, adjusting a process for processing a signal at a node (11-14).

The invention relates to a method for exchanging signals via nodes, and also relates to a destination node, a source node, an intermediate node, a network and a circuit. Examples of such networks are mesh connected local area networks and mesh connected wide area networks. A prior art method is known from U.S. Pat. No. 5,978,364, which discloses a method for routing data packets within a wireless, packet-hopping network. This method combines a prior art purely random routing method and a prior art purely deterministic routing method to maximise the probability of succesful transmissions. When transmitting radio frequency signals from a source node to a destination node, the radio frequency signals may be scattered. Such scatterings create reflected and diffracted radio frequency signals. Many years ago, it was thought that these scatterings would only cause inter-symbol interference and increase the noise in the radio frequency signals. But some years ago it has been realised that the scatterings may be used to increase the performance of wireless networks, like for example the channel capacity between the source node and the destination node. Prior art methods are disadvantageous, inter alia, due to exchanging signals in a relatively non-optimal way. It is an object of the invention, inter alia, to provide a method for exchanging signals in a relatively optimal way. Furthers objects of the invention are, inter alia, to provide a destination node, a source node, an intermediate node, a network and a circuit for exchanging signals in a relatively optimal way. The method according to the invention for exchanging signals via nodes comprises the steps of at a source node, processing a source signal and transmitting the source signal to a destination node via a first signal route comprising an intermediate node and via a different second signal route, with at least one signal route being a wireless signal route; at the destination node, receiving a first destination signal corresponding with the source signal and having followed the first signal route; at the destination node, receiving a second destination signal corresponding with the source signal and having followed the second signal route; at the destination node, processing and correlating the first and second destination signal; and in dependence of a correlation result, adjusting a process for processing a signal at a node. The source node either comprises one output like for example one antenna for transmitting the source signal via the first and second signal routes to the destination node, or comprises two or more outputs like for example two or more antennas for transmitting a first source signal via the first signal route and a second source signal via the second signal route to the destination node. The destination node comprises two or more inputs like for example two or more antennas for receiving the first destination signal and the second destination signal. The fact that the first destination signal and the second destination signal each correspond with the source signal indicates that these signals comprise the same data content, audio content and/or video content. The processing of the first destination signal and of the second destination signal for example comprises transformations and (de)codings and RAKE calculations. The correlation of the first and second destination signal with each other results in an indication, which depends on propagation differences between the signal routes. By adjusting a process for processing a signal at a node in dependence of a correlation result, at this node, the processing is adjusted in such a way that future signals are exchanged in a more optimal way. As a result, the performance of the network comprising these nodes is improved. It should be noted that a node, which is a source node in a certain section of a network and/or at a certain moment in time, may be a destination node or an intermediate node in an other section of the network and/or at an other moment in time. The same holds for a node being a destination node or an intermediate node in the certain section of the network and/or at the certain moment in time. Further, between a source node and a destination node, many more intermediate nodes may be present, in a serial way and/or in a parallel way. A node may be coupled to and/or form (part of a subnetwork. In case of inputs and outputs comprising antennas, the signals will be radio frequency signals. Other kinds of inputs and outputs are not to be excluded, like for example infrared transmitters and infrared receivers, and other transmitters and receivers in lighting infrastructures etc. An embodiment of the method according to the invention is defined in that the process comprises the processing at the destination node. In this case, at the destination node, the processing of the first and second destination signal is adjusted. Then, the performance of the destination node is improved, and the receival of a future first and second destination signal is improved. An embodiment of the method according to the invention is defined by further comprising the step of at the destination node, transmitting, in response to the correlation result, a control signal to the source node for the adjusting of the process; wherein the process comprises the processing at the source node. In this case, the source node is informed of the correlation result via the control signal, and at the source node, the processing of the source signal is adjusted. Then, the performance of the source node is improved, and the transmission of a future source signal is improved. An embodiment of the method according to the invention is defined by further comprising the steps of at the intermediate node, receiving an intermediate signal corresponding with the source signal; at the intermediate node, processing the intermediate signal; and at the destination node, transmitting, in response to the correlation result, a control signal to the intermediate node for the adjusting of the process; wherein the process comprises the processing at the intermediate node. In this case, the intermediate node is informed of the correlation result via the control signal, and at the intermediate node, the processing of the intermediate signal is adjusted. Then, the performance of the intermediate node is improved, and the receival and/or the transmission of a future intermediate signal is improved. An embodiment of the method according to the invention is defined by further comprising the step of at a node, running a learning algorithm for the adjusting of the process. Such a learning algorithm is of common general knowledge itself and may be implemented either in the destination node only or in the node in which the process is adjusted. The learning algorithm stores adaptations made in the past. In case of the performance being improved, the adaptations are to be continued in the same direction as before. In case of the performance being deteriorated, the adaptations are to be reversed and are then to be made in an opposite direction. Stochastic learning itself is for example disclosed on, inter alia, pages 1394 and 1395 of “Neural network using the longitudinal modes of an injection laser with external feedback”, IEEE J. Quantum Electronics, vol. 7, 1996, by S. B. Colak, J. J. H. B. Schleipen and C. T. H. Liedenbaum. An embodiment of the method according to the invention is defined by further comprising the steps of at the source node, generating a label signal for labelling the source signal and transmitting the label signal to the destination node via a third signal route different from the first and second signal route; and at the destination node, detecting the label signal. Such a label signal allows for label switched routing, which itself is of common general knowledge. The source node comprises a further output for transmitting this label signal, and the destination node comprises a third input for receiving this label signal. By using the third route for the transmission of the label signal, the destination node can be informed of a coming arrival of the first and second destination signal. Further, it is possible to inform the one or more intermediate nodes of the coming arrival of the intermediate signals via such a label signal. This way, the efficiency of the destination node and of the intermediate nodes is increased a lot (speed of response—a faster network with small latency). The further output at the source node and the third input at the destination node preferably comprise an infrared transmitter and an infrared receiver, with the other inputs and outputs at the source node and the destination node then preferably comprising antennas. In this case, the label signal is an infrared signal, and the other signals are radio frequency signals. An embodiment of the method according to the invention is defined by further comprising the steps of at the destination node, further processing at least two subsignals of at least one destination signal, which subsignals have followed subroutes of at least one signal route, with these subroutes being different from each other. An input of the destination node may comprise at least two subinputs. In case of the input being an antenna array, each subinput is formed by a part of this antenna array. In case of the input being a collection of infrared receivers, each subinput may be formed by one infrared receiver. By further processing the subsignals received this way, the performance of the destination node is further improved. This further processing of the subsignals for example comprises transformations and (de)codings and RAKE calculations. Adaptivity methods for antenna array purposes are disclosed on, inter alia, page 28, column 2 paragraph 2 of “Spatial and temporal communication theory using adaptive antenna array”, IEEE Personal Comm., February 1998, by R. Kohno. Embodiments of the destination node according to the invention and of the source node according to the invention and of the intermediate node according to the invention correspond with the embodiments of the method according to the invention. Embodiments of the network according to the invention and of the circuit according to the invention correspond with the embodiments of the nodes according to the invention. The invention is based upon an insight, inter alia, that scatterings may be used to increase the performance of wireless networks, and is based upon a basic idea, inter alia, that such scatterings can be simulated by transmitting a signal via different routes/nodes in a network. By processing and correlating the signals received and, in dependence of a correlation result, adapting a process for processing a signal in the network, the performance of the network is improved. The invention solves the problem, inter alia, to provide a method for exchanging signals in a relatively optimal way, and is advantageous, inter alia, in that the network can be designed with relatively much freedom and can be extended in a relatively easy way. These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments(s) described hereinafter. IN THE DRAWINGS FIG. 1 shows in block diagram form a prior art multi-path scattering environment; FIG. 2 shows in block diagram form a network according to the invention comprising one or more nodes according to the invention; FIG. 3 shows in schematical form a network according to the invention with signal paths for guiding space-time-coded signals in combination with weighting coefficients; and FIG. 4 shows in block diagram form a node according to the invention in greater detail. The prior art multi-path scattering environment as shown in FIG. 1 in block diagram form comprises a transmitter 1 and a receiver 2 and three buildings 3-5. A signal transmitted by the transmitter 1 arrives three times at the receiver 2: twice reflected via the buildings 3 and 5, and once diffracted via the building 4. Many years ago, it was thought that such scatterings would only cause inter-symbol interference and increase the noise in the signals. But some years ago it has been realised that the scatterings may be used to increase the performance of wireless networks, like for example the channel capacity between a source node and a destination node. The network according to the invention as shown in FIG. 2 in block diagram form comprises one or more nodes according to the invention, like a source node 11, a destination node 12 and/or intermediate nodes 13-15. The source node 11 transmits a first source signal 21 to the intermediate node 13 and transmits a second source signal 22 to the intermediate node 14 and transmits a third source signal 23 to the intermediate node 14 and transmits a fourth source signal 24 to the intermediate node 15. The first, second and fourth source signals 21,22,24 are for example radio frequency signals and the third source signal 23 is for example an infrared signal, which all for example comprise the same data content, audio content and/or video content (or coded combinatory sets of such contents). The intermediate node 13 receives a first intermediate signal 41 corresponding with the first source signal 21 and transmits a second intermediate signal 42 to the destination node 12. The intermediate node 14 receives a third intermediate signal 51 corresponding with the second source signal 22 and receives a fourth intermediate signal 52 corresponding with the third source signal 23 and transmits a fifth intermediate signal 53 to the destination node 12. The intermediate node 15 receives a sixth intermediate signal 61 corresponding with the fourth source signal 24 and transmits a seventh intermediate signal 62 and an eighth intermediate signal 63 to the destination node 12. The first, second, third, fifth, sixth and seventh intermediate signals 41,42,51,53,61,62 are for example radio frequency signals and the fourth and eighth intermediate signals 52,63 are for example infrared signals, which for example all comprise the same data content, audio content and/or video content (or coded combinatory sets of such contents). The fact that an intermediate signal corresponds with a source signal indicates that both signals comprise the same data content, audio content and/or video content. The destination node 12 receives a first destination signal 31 corresponding with the second intermediate signal 42 from the intermediate node 13 and receives a second destination signal 32 corresponding with the fifth intermediate signal 53 from the intermediate node 14 and receives a third destination signal 33 corresponding with the seventh intermediate signal 62 and a fourth destination signal 34 corresponding with the eighth intermediate signal 63 from the intermediate node 15. The first, second and third destination signals 31,32,33 are for example radio frequency signals and the fourth destination signal 34 is for example an infrared signal, which all for example comprise the same data content, audio content and/or video content (or coded combinatory sets of such contents). The fact that a destination signal corresponds with an intermediate signal indicates that both signals comprise the same data content, audio content and/or video content. A first signal route is for example followed by the signals 21,41,42,31. A second signal route is for example followed by the signals 22,51,53,32. A third signal route is for example followed by the signals 23,52,53,32. A fourth signal route is for example followed by the signals 24,61,62,33. A fifth signal route is for example followed by the signals 24,61,63,34. Further signal routes are not to be excluded. For example, a further signal route could flow via two or three of the intermediate nodes 13-15, and another signal route could flow directly from the source node to the destination node. A node may further communicate wiredly and/or wirelessly with further nodes not shown and/or with a further network not shown, and may represent a subnetwork etc. At the destination node 12, the different destination signals 31-34 are, usually individually, processed, and, usually for example per pair, correlated. In dependence of one or more correlation results, one or more processes for processing signals in one or more nodes 11-15 are to be adjusted. By adjusting these processes in dependence of the correlation results, in these nodes 11-15, the processing is adjusted in such a way that future signals are exchanged in a more optimal way. As a result, the performance of the network comprising these nodes 11-15 is improved. This will be described in greater detail for FIG. 4. It should be noted that a node, which is a source node in a certain section of a network and/or at a certain moment in time, may be a destination node or an intermediate node in an other section of the network and/or at an other moment in time. The same holds for a node being a destination node or an intermediate node in the certain section of the network and/or at the certain moment in time. For example, in case of a further node not shown being situated near and being able to communicate wirelessly with the node 12, as soon as the node 12 has received, processed and correlated the destination signals described above, the node 12 will transmit the signal to the further node, and at this moment, the node 12 has suddenly become a source node 12. So, the function of each node 11-15 depends on the section of the network which is active and/or on the moment in time at which activities take place. The network according to the invention as shown in FIG. 3 in schematical form comprises the same nodes 11-15, whereby a signal path 71 is present from node 11 to node 13, a signal path 72 is present from node 11 to node 14, a signal path 73 is present from node 11 to node 15, a signal path 74 is present from node 13 to node 14, a signal path 75 is present from node 15 to node 14, a signal path 76 is present from node 13 to node 12, a signal path 77 is present from node 14 to node 12, and a signal path 78 is present from node 15 to node 12. Via these signal paths 71-78, space-time-coded signals are transmitted, and weighting coefficients are introduced per path (w1 for path 71, w2 for path 72 etc. with w usually being a complex number), as follows. A space-time coded signal STC is sent from the node 11 via the paths 71,72,73 to the nodes 13,14,15. In the node 13, a signal STC·w1 is received, in the node 14, a signal STC·w2 is received, and in the node 15, a signal STC·w3 is received. The node 14 further receives via the path 74 a signal STC·w1·w4 and receives via the path 75 a signal STC·w3·w5. The node 12 receives via the path 76 a signal STC·w1·w6, and receives via the path 77 a signal STC·(w2+w1·w4+w3·w5)·w7, and receives via the path 78 a signal STC·w3·w8. This is all under the assumption that the space-time coded signal STC itself is not changed inside the nodes 13-15. The signals received by the node 15 are to be correlated, and in dependence of one or more correlation result, the weighting coefficients w1 for path 71, w2 for path 72 etc. are to be adjusted. The adjustment of a weighting coefficient for a path is usually done in one of the two nodes forming the start and the end of this path. Further, in dependence of one or more correlation results, in each node, the amplitude, phase and/or delay of the signal may be adapted, at carrier level and/or at symbol level. The node 80 according to the invention as shown in FIG. 4 in greater detail in block diagram form comprises an antenna 81 coupled via a transmitting/receiving unit 91 and a further processing unit 101 to a circuit 90, comprises two antennas 82 coupled via a transmitting/receiving unit 92 and a further processing unit 102 to the circuit 90, comprises an infrared 15 transmitter/receiver 83 coupled via a transmitting/receiving unit 93 and a further processing unit 103 to the circuit 90, comprises an light transmitter/receiver 84 coupled via a transmitting/receiving unit 94 and a further processing unit 104 to the circuit 90, and comprises an infrared transmitter/receiver 85 coupled via a transmitting/receiving unit 95 and a -20 further processing unit 105 to the circuit 90. The circuit 90 comprises a buffer/switch 86 coupled to each further processing unit 101-105 and to a processing unit 87 and to a controller 88 and to a correlating unit 89, with the controller 88 comprising a memory and further being coupled directly to the processing unit 87 and the correlating unit 89. The latter units 87 and 89 are 25 also coupled directly to each other. The processing unit 87 is further coupled to each transmitting/receiving unit 91-95 for controlling purposes, and to a unit 96 for label detection, which unit 96 is further coupled to the further processing unit 105. Any labels received via for example the infrared transmitter/receiver 85 and detected and/or processed by the unit 96 can be highly useful to switch 30 any signals arriving via the antennas 81 and 82 and the other transmitter/receivers 83 and 84 by using label switching to speed up the operation of the node. The processing unit 87 is further coupled to a unit 97 which is further coupled to the light transmitter/receiver 84 for controlling the light transmitter/receiver 84, like for example in a Light Infrastructure re-use for Multimedia Broadcast Application style network. This unit 97 is for example further coupled to a power supply not shown in FIG. 4. In case of the node 80 representing the destination node 12, for example two destination signals are received, the first destination signal 31 arriving via the antenna 81 and the second destination signal 32 arriving via the antennas 82. The first destination signal 31 passes the transmitting/receiving unit 91 for amplification, frequency translation, filtering, demodulation etc. and passes the further processing unit 101 to be discussed later. The second destination signal 32 passes the transmitting/receiving unit 92 for amplification, frequency translation, filtering, demodulation etc. and passes the further processing unit 102 to be discussed later. Via the buffer/switch 86, both signals are supplied to the processing unit 87 for performing one or more transformations, one or more (de)codings and/or one or more RAKE calculations etc. Then both signals are supplied to the correlating unit 89 for being correlated. The correlation of the first and second destination signal 31,32 with each other results in an indication, which depends on propagation differences between the signal routes followed by these destination signals (and their previous intermediate signals and their previous source signals). According to a first option, in dependence of a correlation result, the process comprising the processing of the destination signals 31,32 is adjusted. In other words, in dependence of the correlation result, the processing unit 87 is adjusted in such a way that future destination signals arriving at this node 80 are dealt with in a more optimal way. The adjustment of the processing unit 87 for example comprises an adjustment of the weighting coefficients discussed for FIG. 3 and/or comprises an adjustment of the one or more transformations, of the one or more (de)codings and/or of the one or more RAKE calculations etc. Alternatively and/or in addition, a further adjustment of the amplitude, of the phase and/or of the delay of the signal, at carrier level and/or at symbol level can be made via the couplings between the processing unit 87 and the transmitting/receiving units 91,92. So, the processing in the processing unit 87 and/or in the transmitting/receiving units 91,92 is adjusted, and as a result, the performance of the network comprising this node 80 is improved. These adjustments are such that the correlation between the received signals is at least reduced and preferably minimized. In other words, the destination signals should be at least less correlated than before and preferably uncorrelated as much as possible. According to a second option, in dependence of a correlation result, for example the controller 88 generates a control signal which via either transmitting/receiving unit 91,92 and antenna 81,82 or via an other transmitting/receiving unit 93-95 and transmitter/receiver 83-85 is transmitted to the source node 11 or the intermediate node 13,14 for in these nodes 11,13,14 adjusting a process for processing source signals or intermediate signals as discussed below. In case of the node 80 representing the source node 11, for example two source signals are transmitted, the first source signal 11 via the antenna 81 and the second source signal 22 via one or more of the antennas 82. Thereto, a data signal, an audio signal and/or a video signal is possibly processed in the processing unit 87, which performs one or more transformations and/or one or more (de)codings etc. Then the signal is supplied, via the buffer/switch 86, to the transmitting/receiving unit 91 for modulation, filtering, frequency translation, amplification etc. and to the transmitter/receiver 92 for modulation, filtering, frequency translation, amplification etc. for being transmitted via the antennas 81,82 as the first and second source signal. Thereby, the signals pass the further processing units 101,102 to be discussed later. After some time, the above described control signal arrives, either via the transmitting/receiving unit 91,92 and antenna 81,82 or via an other transmitting/receiving unit 93-95 and transmitter/receiver 83-85. In response to this control signal, the process comprising the processing of the source signals 21,22 is adjusted. In other words, in dependence of the correlation result of the correlation performed in the destination node 12, the processing unit 87 is adjusted in such a way that future source signals to be transmitted from this node 80 are dealt with in a more optimal way. The adjustment of the processing unit 87 for example comprises an adjustment of the weighting coefficients discussed for FIG. 3 and/or comprises an adjustment of the one or more transformations, of the one or more (de)codings etc. Alternatively and/or in addition, a further adjustment of the amplitude, of the phase and/or of the delay of the signal, at carrier level and/or at symbol level can be made. So, the processing in the processing unit 87 and/or in the transmitting/receiving units 91,92 is adjusted, and as a result, the performance of the network comprising this node 80 is improved. In case of the node 80 representing the intermediate node 13, for example the first intermediate signal 41 is received via the antenna 81 and the second intermediate signal 42 is transmitted via one or more of the antennas 82. The first intermediate signal 41 passes the transmitting/receiving unit 91 for amplification, frequency translation, filtering, demodulation etc. and passes the further processing unit 101 to be discussed later. Via the buffer/switch 86, the signal is supplied to the processing unit 87 for performing one or more transformations and one or more (de)codings etc. Then, the processing unit 87 again performs, possibly in a reversed way, the one or more transformations and the one or more (de)codings etc. and the signal is supplied, via the buffer/switch 86, to the transmitting/receiving unit 92 for modulation, filtering, frequency translation, amplification etc. for being transmitted via the antenna 82 as the second intermediate signal 42. Thereby, the signal passes the further processing units 102 to be discussed later. After some time, the above described control signal arrives, either via the transmitting/receiving unit 91,92 and antenna 81,82 or via an other transmitting/receiving unit 93-95 and transmitter/receiver 83-85. In response to this control signal, the process comprising the processing of the intermediate signals 41,42 is adjusted. In other words, in dependence of the correlation result of the correlation performed in the destination node 12, the processing unit 87 is adjusted in such a way that future intermediate signals to be received by and/or to be transmitted from this node 80 are dealt with in a more optimal way. The adjustment of the processing unit 87 for example comprises an adjustment of the weighting coefficients discussed for FIG. 3 and/or comprises an adjustment of the one or more transformations, of the one or more (de)codings etc. Alternatively and/or in addition, a further adjustment of the amplitude, of the phase and/or of the delay of the signal, at carrier level and/or at symbol level can be made. So, the processing in the processing unit 87 and/or in the transmitting/receiving units 91,92 is adjusted, and as a result, the performance of the network comprising this node 80 is improved. Preferably, in node 80, a learning algorithm is run for the adjusting of the process, for example via the controller 88. In case of the node 80 representing the destination node 12, the algorithm is located close to the correlating unit which generates the correlation results. In case of the node 80 representing the source node 11 or the intermediate node 13, the algorithm will react to the control signal coming from the destination node 12. Such a learning algorithm is of common general knowledge itself and stores adaptations made in the past. In case of the performance being improved, the adaptations are to be continued in the same direction as before. In case of the performance being deteriorated, the adaptations are to be reversed and are then to be made in an opposite direction. Preferably, at the source node 11, a label signal is generated, for example via the controller 88, for labelling the source signal 21,22. This label signal is however transmitted to the destination node 12 separately from the source signal 21,22 via a third signal route different from the first and second signal route. At the destination node 12, the label signal is detected, for example via the unit 96, in case of the label signal arriving via transmitter/receiver 85. Such a label signal allows for label switched routing, which itself is of common general knowledge. Thereto, the source node 11 for example uses the transmitter/receiver 83, and the destination node 12 for example uses the transmitter/receiver 85. By using the third route for the transmission of the label signal, the destination node 12 can be informed of a coming arrival of the first and second destination signal 31,32. Further, it is possible to inform the one or more intermediate nodes 13-15 of the coming arrival of the intermediate signals via such a label signal. This way, the efficiency of the destination node 12 and of the intermediate nodes 13-15 is increased a lot. Each one of the further processing units 101-104 may, like the further processing unit 105, also be coupled to a label detection unit. Alternatively, such a label detection unit may have a more centralized location for example close to the buffer/switch 86, and/or may for example be integrated into the further processing units 101-105 and/or into the processing unit 87 etc. The transmitting/receiving units 91-95 for example represent a physical layer (comprising a physical medium dependent sublayer and a physical medium attachment layer and a physical coding sublayer) and/or a radio frequency part of a transceiver, and the further processing units 101-105 for example represent a data link layer (comprising a medium access control sublayer and a logical link control sublayer) and/or a baseband part of a transceiver. In that case, processing unit 87, controller 88 and/or correlating unit 89 take care of the network layer (IP packets) and the transport layer (TCP protocol), and the processing unit 87 can easily control the transmitting/receiving units 91-95, due to a media independent interface being present between the physical layer and the data link layer. At this media independent interface, the necessary digital signals of a protocol exist. Further, the transmitting/receiving units 91-95 comprise circuits like filters, amplifiers, mixers, controlled oscillators, delay lines, gain controllers, delay lines, converters etc. which easily allow for example the adjustment of an amplitude and/or of a phase or a delay. Preferably, instead of for example one antenna 81 or 82, an antenna array is used. In that case, at least one of the destination signals 31,32 will comprise at least two subsignals, which subsignals have followed different subroutes of at least one signal route. Or, instead of for example one transmitter/receiver 83, 84 or 85, an array of transmitters/receivers is used. When using arrays, the further processing units 101-105 will need to perform a more complex further processing. This further processing of the subsignals for example comprises transformations and (de)codings and RAKE calculations etc. A further processing unit 101-105 then for example comprises per subsignal a number of delay elements coupled serially to each other, with their outputs and the input of the first delay element being coupled to inputs of multipliers for multiplying their input signals with a coefficient. Outputs of these multipliers are coupled to inputs of a summing element for summing the output signals of these multipliers, for all subsignals arrived via the array. In response to the correlation results and/or the control signal, the number of delay elements as well as the coefficients can be adjusted, for improving the performance of the network. So, in case of using arrays, a further process might be adjusted in addition. It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb “to comprise” and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

20071207

20110301

20080710

68052.0

H04B714

TAYLOR, BARRY W

WIRELESS MULTI-PATH TRANSMISSION SYSTEM (MIMO) WITH CONTROLLED REPEATERS IN EACH SIGNAL PATH

UNDISCOUNTED

ACCEPTED

H04B

ACCEPTED

Control Arm for the Wheel Suspension of a Motor Vehicle

A control arm for the wheel suspension of a motor vehicle with an arm body 1 made of at least one sheet metal part and at least one pivotal point for connection to a fixing point on the vehicle body side is introduced, whereby the pivotal point is designed as a circular mounting bushing 2 for an elastic bearing element 3. According to the present invention, the wall of the mounting bushing 2 is molded in one piece with the arm body 1 and consists of a bearing area 4 having a ring-shaped design as well as a mounting strap 5 fixed on the arm body 1.

1. A control arm for the wheel suspension of a motor vehicle, the control arm comprising: an arm body made of at least one sheet metal part; and at least one pivotal point for connection to a fixing point on the vehicle body side, whereby the pivotal point is designed as a circular mounting bushing for an elastic bearing element, wherein a wall of said mounting bushing is molded in one piece with said arm body, said wall comprising a bearing area having a ring-shaped design as well as a mounting strap fixed on said arm body. 2. A control arm in accordance with claim 1, wherein said mounting strap is fixed on said arm body by means of welding. 3. A control arm in accordance with claim 1, wherein said mounting strap is fixed on said arm body by means of gluing. 4. A control arm in accordance with claim 1, wherein said mounting strap is fixed on said arm body by means of riveting. 5. A control arm in accordance with claim 1, wherein said mounting strap is fixed on said arm body by means of bolting. 6. A control arm in accordance with claim 1, wherein said mounting strap is fixed on said arm body by means of clinching. 7. A control arm in accordance with claim 1, wherein said mounting strap is fixed on said arm body by means of tox clinching. 8. A control arm in accordance with claim 1, wherein said bearing area and said mounting strap essentially have identical width dimensions. 9. A motor vehicle wheel suspension control arm comprising: an arm body made of at least one sheet metal part; and a circular mounting bushing comprising a wall provided as an integral part of said at least one sheet metal part and including a bearing area with a ring-shape as well as a mounting strap. 10. A control arm in accordance with claim 9, wherein said mounting strap is fixed on said arm body by welding. 11. A control arm in accordance with claim 9, wherein said mounting strap is fixed on said arm body by glue. 12. A control arm in accordance with claim 9, wherein said mounting strap is fixed on said arm body by one or more rivets. 13. A control arm in accordance with claim 9, wherein said mounting strap is fixed on said arm body by one or more bolt. 14. A control arm in accordance with claim 9, wherein said mounting strap is fixed on said arm body by a clinch connection. 15. A control arm in accordance with claim 9, wherein said mounting strap is fixed on said arm body by a tox clinch connection 16. A control arm in accordance with claim 9, wherein said bearing area and said mounting strap essentially have identical width dimensions. 17. A control arm in accordance with claim 1, further comprising: a bearing element in said ring-shape bearing area. 18. A motor vehicle wheel suspension control arm formed by the steps comprising: providing a single sheet of metal forming at least a part of an arm body and a circular mounting bushing with a ring-shape bearing area and a mounting strap; and fixing the mounting strap to said arm body. 19. A motor vehicle wheel suspension control arm according to claim 18, further comprising: providing another metal sheet, wherein said arm is formed of said metal sheet connected to said another metal sheet. 20. A motor vehicle wheel suspension control arm according to claim 18, further comprising: an elastic bearing element in said ring-shape bearing area.

CROSS REFERENCE TO RELATED APPLICATIONS This application is a United States National Phase application of International Application PCT/DE2005/000353 and claims the benefit of priority under 35 U.S.C. §119 of German Patent Application DE 10 2004 011 766.7 filed Mar. 9, 2004, the entire contents of which are incorporated herein by reference. FIELD OF THE INVENTION The present invention pertains to a control arm for the wheel suspension of a motor vehicle with an arm body made of at least one sheet metal part and at least one pivotal point located on the arm body for the connection to a fixing point on the vehicle body side, whereby the pivotal point is designed as a circular mounting bushing for an elastic bearing element. BACKGROUND OF THE INVENTION Control arms of this type are also called suspension arms and usually consist of single or double steel sheets connected to one another, whereby the sheet construction can be provided in sections to increase the stiffness with corrugations or edgings. The control arms in this case have pivotal points for fixing wheel-related components as well as, in addition, pivotal points for fixing the control arm on the vehicle body side. These pivotal points are usually designed such that a certain mobility, which is created by means of an elastic bearing, for example, by means of rubber elements, is guaranteed in these points. These rubber elements are mounted on the control arm in circular mounting bushings, which, in the state of the art, are connected to the actual arm body in various ways. For example, auxiliary housings, which are bolted on or riveted on the control arm as separate components, are known. Other types of construction provide for connecting additional sheet metal shells for mounting rubber elements or corresponding mounting bushings to the arm housings, for example, by means of welding operations. All of the structural measures described have the drawback that the mounting bushings or bearing components to be connected to the arm housing are manufactured in separate production steps and are then to be connected to the actual arm housing. This means an increased number of production steps and mounting steps and increased production costs connected therewith, whereby, moreover, additional components have negative consequences in relation to warehousing costs. In addition, possibilities of providing two-sheet arm bodies, which consist of upper and lower parts welded to one another, with two-part mounting bushings, as this is disclosed, for example, in Patent Application WO 02/074562 A2, have become known from the state of the art. The drawback of the structural embodiment shown there lies in an increased inaccuracy of the mounting bushing as a result of the split located in the mounting plane. SUMMARY OF THE INVENTION Therefore, starting from the existing state of the art, the object of the present invention is to provide a design of a control arm for the wheel suspension of a motor vehicle in relation to its pivotal points, particularly to the vehicle body, so that a simplified, cost-effective production is guaranteed and the control arm is optimized with regard to its weight. According to the invention, a control arm for the wheel suspension of a motor vehicle is provided with an arm body made of at least one sheet metal part and with at least one pivotal point or region for connection to a fixing point on the vehicle body side. The pivotal point is designed as a circular mounting bushing for an elastic bearing element. This mounting bushing is molded in one piece with the arm body. The mounting bushing comprises a bearing area having a ring-shaped design as well as a mounting strap fixed on the arm body. This object is accomplished according to the present invention in that the wall of the mounting bushing is molded in one piece with the arm body and consists of a bearing area having a ring-shaped design as well as a mounting strap fixed on the arm body. Due to this structural design, the additional components of the pivotal points, which were needed up to now for the manufacture of the control arms of this class, are omitted; moreover, the manufacture of the arm body is simplified in that the shaping of the necessary mounting bushing for the elastic bearing element can be performed simultaneously with the transforming of the sheet components used for the arm body. For the fixing of the mounting strap on the arm body, it has proven to be advantageous if this strap is fixed on the arm body by means of welding, gluing, riveting, bolting, clinching or tox clinching. The types of fixing mentioned represent a cost-effective variant of the processing in relation to the necessary manufacturing procedures. In addition, it has proven to be expedient to design the bearing area and the mounting strap, such that these essentially have identical width dimensions. Two exemplary embodiments of the subject of the present invention are explained in detail below based on the attached drawings. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated. BRIEF DESCRIPTION OF THE DRAWINGS In the drawings: FIG. 1 is a partial view of a control arm according to the present invention in the area of the pivotal point in case of a one-sheet embodiment of the arm body; and FIG. 2 is a partial view of another control arm according to the present invention in the area of the pivotal point in case of a two-sheet embodiment of the arm body. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings in particular, the arm body 1 of a control arm according to the present invention shown in FIG. 1 consists of a steel sheet component, in which a mounting bushing, identified in its entirety by 2, is arranged in a corner area. A schematically shown bearing element 3 in the form of a rubber ring is inserted into the mounting bushing. The mounting bushing 2 consists, as this is evident from FIG. 1, of a bearing area 4 of a ring-shaped design as well as a mounting strap 5. In the exemplary embodiment shown, the bearing area 4 and the mounting strap 5 have the same width and are molded in the shape of a strap in the unmolded raw state of the arm body as a component of the latter. Within the framework of the transforming process for manufacturing the final arm body contour, the bearing area 4 has a ring-shaped design, and the mounting strap 5 is molded on such that it comes to lie on the top side of the arm body 1. In a final procedure, the mounting strap 5 is then undetachably connected to the arm body by means of a welding or gluing procedure. The welding procedure can be carried out by means of spot welding. As an alternative to this, welding around the edges of the mounting strap is conceivable. The exemplary embodiment shown in FIG. 2 is distinguished from the one shown in FIG. 1 in that here the arm body 1 is composed of a lower sheet 1a and an upper sheet 1b. The upper sheet 1b and the lower sheet 1a are welded to one another. The mounting bushing 2 is embodied as a strap of the lower sheet 1a in the unprocessed state of the arm body 1 and is transformed within the framework of the production process, such that, on the one hand, the bearing area of a ring-shaped design is produced for accommodating an elastic bearing element as well as the mounting strap 5 in a complementary manner. In the embodiment shown, the mounting strap 5 comes to lie on the top side of the upper sheet 1b and, similar to the view in FIG. 1, is fixed here by means of gluing, welding or riveting on the upper sheet 1b. While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

<SOH> BACKGROUND OF THE INVENTION <EOH>Control arms of this type are also called suspension arms and usually consist of single or double steel sheets connected to one another, whereby the sheet construction can be provided in sections to increase the stiffness with corrugations or edgings. The control arms in this case have pivotal points for fixing wheel-related components as well as, in addition, pivotal points for fixing the control arm on the vehicle body side. These pivotal points are usually designed such that a certain mobility, which is created by means of an elastic bearing, for example, by means of rubber elements, is guaranteed in these points. These rubber elements are mounted on the control arm in circular mounting bushings, which, in the state of the art, are connected to the actual arm body in various ways. For example, auxiliary housings, which are bolted on or riveted on the control arm as separate components, are known. Other types of construction provide for connecting additional sheet metal shells for mounting rubber elements or corresponding mounting bushings to the arm housings, for example, by means of welding operations. All of the structural measures described have the drawback that the mounting bushings or bearing components to be connected to the arm housing are manufactured in separate production steps and are then to be connected to the actual arm housing. This means an increased number of production steps and mounting steps and increased production costs connected therewith, whereby, moreover, additional components have negative consequences in relation to warehousing costs. In addition, possibilities of providing two-sheet arm bodies, which consist of upper and lower parts welded to one another, with two-part mounting bushings, as this is disclosed, for example, in Patent Application WO 02/074562 A2, have become known from the state of the art. The drawback of the structural embodiment shown there lies in an increased inaccuracy of the mounting bushing as a result of the split located in the mounting plane.

<SOH> SUMMARY OF THE INVENTION <EOH>Therefore, starting from the existing state of the art, the object of the present invention is to provide a design of a control arm for the wheel suspension of a motor vehicle in relation to its pivotal points, particularly to the vehicle body, so that a simplified, cost-effective production is guaranteed and the control arm is optimized with regard to its weight. According to the invention, a control arm for the wheel suspension of a motor vehicle is provided with an arm body made of at least one sheet metal part and with at least one pivotal point or region for connection to a fixing point on the vehicle body side. The pivotal point is designed as a circular mounting bushing for an elastic bearing element. This mounting bushing is molded in one piece with the arm body. The mounting bushing comprises a bearing area having a ring-shaped design as well as a mounting strap fixed on the arm body. This object is accomplished according to the present invention in that the wall of the mounting bushing is molded in one piece with the arm body and consists of a bearing area having a ring-shaped design as well as a mounting strap fixed on the arm body. Due to this structural design, the additional components of the pivotal points, which were needed up to now for the manufacture of the control arms of this class, are omitted; moreover, the manufacture of the arm body is simplified in that the shaping of the necessary mounting bushing for the elastic bearing element can be performed simultaneously with the transforming of the sheet components used for the arm body. For the fixing of the mounting strap on the arm body, it has proven to be advantageous if this strap is fixed on the arm body by means of welding, gluing, riveting, bolting, clinching or tox clinching. The types of fixing mentioned represent a cost-effective variant of the processing in relation to the necessary manufacturing procedures. In addition, it has proven to be expedient to design the bearing area and the mounting strap, such that these essentially have identical width dimensions. Two exemplary embodiments of the subject of the present invention are explained in detail below based on the attached drawings. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.

20060907

20091006

20080703

68838.0

B60G700

FLEMING, FAYE M

CONTROL ARM FOR THE WHEEL SUSPENSION OF A MOTOR VEHICLE

UNDISCOUNTED

ACCEPTED

B60G

ACCEPTED

Medication dispensing apparatus with spring-driven locking feature enabled by administration of final dose

A medication dispensing apparatus with a spring-driven locking feature includes a drive member movable in a distal direction within a housing, and a fluid container with a piston that is advanceable by the drive member (60) when such drive member is moved distally by a driving means. The apparatus includes a latching element (180) having a skid (190) that is slidable along a surface of the drive member as the drive member passes distally during advancement. The drive member is arranged with the skid so as to maintain a latching lip of the latching element against a spring force in a first position free of the driving means during dose preparing and injecting prior to a final dose administration. The skid-engaging surface shifts distally of the skid such that the skid passes beyond a proximal end of that surface upon administration of a final dose, whereby the latching lip is urged by the spring force from the first position to a second position to physically lock the driving means to prevent further dose preparing and injecting.

1. A medication dispensing apparatus comprising: a housing; a drive member within said housing and movable in a distal direction; a fluid container defining a medicine-filled reservoir with a movable piston at one end and an outlet at the other end, said piston engageable by said drive member to be advanced toward said outlet a distance equal to a distal movement of said drive member when said drive member is moved distally; means for driving said drive member distally; a latching element including a latching lip and a skid; said drive member including an axially extending, skid-engaging surface along which said skid is slidable as said drive member passes distally during advancement, said skid-engaging surface having an axial length and a proximal end, said drive member along said axial length structured and arranged with said skid so as to maintain said latching lip against a spring force in a first position free of said driving means during dose preparing and injecting prior to a final dose administration; and wherein said skid-engaging surface shifts distally of said skid such that said skid passes beyond the proximal end upon administration of a final dose, whereby said latching lip is urged by said spring force from said first position to a second position to physically lock said driving means to prevent further dose preparing and injecting. 2. The medication dispensing apparatus of claim 1 wherein said proximal end of said skid-engaging surface comprises a proximal end of said drive member. 3. The medication dispensing apparatus of claim 1 wherein said skid is disposed distally of said latching lip. 4. The medication dispensing apparatus of claim 1 wherein said skid comprises a blade shape member that extends axially, and wherein said latching lip comprises a transversely extending flange. 5. The medication dispensing apparatus of claim 1 wherein in said second position said latching lip engages a latchable element disposed on a gear set carrier of said driving means. 6. The medication dispensing apparatus of claim 5 wherein said latchable element comprises a ramped distal face over which said latching lip is cammable to reach a latching engagement with said latchable element. 7. The medication dispensing apparatus of claim 5 wherein said latching element is axially fixed to said housing by at least one flange fit into a slot provided in said housing. 8. The medication dispensing apparatus of claim 5 wherein said spring force acting on said latching element comprises a resiliency of said latching element tending to return said latching lip to a neutral arrangement. 9. The medication dispensing apparatus of claim 8 wherein said latching element comprises a one piece metal stamping. 10. The medication dispensing apparatus of claim 1 wherein said skid-engaging surface is smooth. 11. The medication dispensing apparatus of claim 1 wherein said latching lip comprises a rim along an opening through which a latchable element extends to reach a latching engagement with said latching element.

BACKGROUND OF THE INVENTION The present invention pertains to medication dispensing devices, and, in particular, to a portable medication dispensing device such as an injector pen. Patients suffering from a number of different diseases frequently must inject themselves with medication. To allow a person to conveniently and accurately self-administer medicine, a variety of devices broadly known as injector pens or injection pens have been developed. Generally, these pens are equipped with a cartridge including a piston and containing a multi-dose quantity of liquid medication. A drive member, extending from within a base of the injector pen and operably connected with typically more rearward mechanisms of the pen that control drive member motion, is movable forward to advance the piston in the cartridge in such a manner to dispense the contained medication from an outlet at the opposite cartridge end, typically through a needle that penetrates a stopper at that opposite end. In disposable pens, after a pen has been utilized to exhaust the supply of medication within the cartridge, the entire pen is discarded by a user, who then begins using a new replacement pen. In reusable pens, after a pen has been utilized to exhaust the supply of medication within the cartridge, the pen is disassembled to allow replacement of the spent cartridge with a fresh cartridge, and then the pen is reassembled for its subsequent use. Some injector pens allow a dose to be set that is larger than the amount of useable medicine remaining in the pen. While some users may find such settability undesirable, providing an insufficient remaining dose indicator may not be practical in all cases, such as due to it complicating the pen design. Still further, a shortcoming with some injector pens is that the design platform on which they are based may not allow a manufacturer sufficient options as to the mechanical advantage to provide, such as a mechanical advantage that can be very small in order to readily inject a large volume dose, or which mechanical advantage can be quite large so as to deliver a small volume dose with a suitable plunger travel. Thus, it would be desirable to provide an apparatus that can overcome one or more of these and other shortcomings of the prior art. BRIEF SUMMARY OF THE INVENTION In one form thereof, the present invention provides a medication dispensing apparatus including a housing, a drive member within the housing and movable in a distal direction, a fluid container defining a medicine-filled reservoir with a movable piston at one end and an outlet at the other end, the piston being engageable by the drive member to be advanced toward the outlet a distance equal to a distal movement of the drive member when the drive member is moved distally, a means for driving the drive member distally, and a latching element including a latching lip and a skid. The drive member includes an axially extending, skid-engaging surface along which the skid is slidable as the drive member passes distally during advancement. The skid-engaging surface has an axial length and a proximal end, and the drive member along the axial length is structured and arranged with the skid so as to maintain the latching lip against a spring force in a first position free of the driving means during dose preparing and injecting prior to a final dose administration. The skid-engaging surface shifts distally of the skid such that the skid passes beyond the proximal end upon administration of a final dose, whereby the latching lip is urged by the spring force from the first position to a second position to physically lock the driving means to prevent further dose preparing and injecting. One advantage of the present invention is that a medication dispensing apparatus can be provided with an uncomplicated and robust mechanism for automatically locking the apparatus to prevent further use after a final dose of the apparatus has been administered. Yet another advantage of the present invention is that a medication dispensing apparatus can be provided which is readily adaptable by the manufacturer to furnish a mechanical advantage during dose administration selected from a wide range of such advantages, such as a small advantage of about two for a large volume dose, up to a large advantage of about sixteen for a small volume dose. Another advantage of the present invention is that a medication dispensing apparatus can be provided which is internally configured to utilize space efficiently to allow for a compact design that contributes to a small and symmetrical design-of the apparatus. BRIEF DESCRIPTION OF THE DRAWINGS The above-mentioned and other advantages and objects of this invention, and the manner of attaining them, will become more apparent, and the invention itself will be better understood by reference to the following description of embodiments of the invention taking in conjunction with the accompanying drawings, wherein: FIG. 1 is a side view of a first embodiment of a medication dispensing apparatus of the present invention, which apparatus is arranged in a ready or ready-to-be-cocked state;. FIG. 2 is a longitudinal cross-sectional view of the medication dispensing apparatus of FIG. 1; FIG. 3 is a longitudinal cross-sectional view, taken along line 3-3 of FIG. 1, of the medication dispensing apparatus of FIG. 1; FIG. 4 is an exploded, top perspective view of the medication dispensing apparatus of FIG. 1, wherein an apparatus cap is also shown; FIG. 5 is a bottom perspective view of the medication dispensing apparatus of FIG. 4; FIG. 6 is a bottom perspective view of the medication dispensing apparatus of FIG. 1, and with a bottom portion of its housing removed to better show internal components of the apparatus; FIG. 7 is a bottom perspective view of the medication dispensing apparatus of FIG. 1, with portions of its housing and larger pinion removed to better show internal components of the apparatus; FIG. 8 is a bottom perspective view of the medication dispensing apparatus of FIG. 1 after being manipulated from its ready state to a cocked or ready-to-inject state, with portions of its housing and larger pinion removed to better show internal components of the apparatus; FIG. 9 is a top perspective view of the medication dispensing apparatus of FIG. 1, with a top portion of its housing removed to better show internal components of the apparatus; FIG. 10 is a top perspective view of the medication dispensing apparatus of FIG. 1 after being manipulated from its ready state to a ready-to-inject state, with a portion of its housing removed to better show internal components of the apparatus; FIG. 11 is a top perspective view of a portion of the apparatus of FIG. 1 after being manipulated from its ready state to a ready-to-inject state, with portions of its housing and pinion-engaging piece removed to better show internal components of the apparatus; FIG. 12 is a perspective view of a housing half showing a guide of a partial-cocking-preventing mechanism; and FIG. 13 is an exploded, top perspective view of another embodiment of a medication dispensing apparatus of the present invention, wherein the apparatus cap is also shown. Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments of the present invention, the drawings are not necessarily to scale, and certain features may be exaggerated or omitted in some of the drawings in order to better illustrate and explain the present invention. DETAILED DESCRIPTION OF THE INVENTION Referring now to FIGS. 1-12, there is shown a first embodiment of a medication dispensing apparatus of the present invention. Any directional references in this detailed description with respect to FIG. 1 or any of the other Figures, such as front, side or back, or up or down, or top or bottom, are intended for convenience of description, and by itself does not limit the present invention or any of its components to any particular positional or spatial orientation. The apparatus, generally designated 20, is an injector pen of a design that builds upon the teachings of U.S. Provisional Patent Application 60/557,545, which also was filed with the United States Receiving Office of the World Intellectual Property Organization and assigned application number ______ on even date with the international filing of this application, the entire contents of which are hereby incorporated by reference. Medication injector pen 20 is a disposable pen that is repeatedly operable by a user to deliver a fixed dose that is established by the pen manufacturer. The distal portion 22 of injector pen 20 includes a plastic tubular retainer 24 that holds a cartridge 28 therein. Cartridge 28 is of conventional design, including a medicine-filled reservoir 30 sealed at one end by a slidable piston 32 and sealed at the other end by an injection needle-pierceable septum 33. Retainer 24 is made of a clear plastic material to allow a user to see the contents of reservoir 30. Threading 26 on the stepped-down distal end of retainer 24 allow a releaseably mounting of, for example, a conventional injection needle assembly shown at 25. Pen 20 is shown in FIGS. 4 and 5 as having a protective cap 29 that removably mounts to the cartridge retainer 24 for protection thereof, which cap has a distal end design at 31 to prevent the capped pen from rolling. The proximal portion 34 of injector pen 20 includes a protective external housing 35 that is somewhat elliptical in transverse cross-section. To facilitate assembly of the apparatus, housing 35 is formed from multiple, interconnected injection molded plastic pieces. Housing 35 is shown having longitudinal halves 36 and 38 that are is complementarily designed to mate and be fixedly secured together during manufacture, such as via ultrasonic welding. The interior surfaces 37 and 39 of housing halves 36 and 38, respectively, are shown formed with a variety of ribs and bulkheads that serve to maintain the alignment and guide the motion of the apparatus components disposed within housing 35. Housing halves 36 and 38 respectively include distally projecting, curved flanges 40 and 42. During apparatus manufacture, to mount the fluid container to the assembled housing, flanges 40 and 42 are first inserted within the proximal end of retainer 24 radially outward of the cartridge body, and then fixedly secured to the retainer, such as via adhesives or ultrasonic welding. When retainer 24 and housing 35 are so secured, cartridge 28 is axially sandwiched between the interior surface of retainer 24 and an internal bulkhead 44 of the housing to prevent axial movement of the cartridge during use. Pen proximal portion 34 includes an axially advanceable drive member generally designated 50, a gear set generally designated 52, and a plunger member generally designated 54. Drive member 50 includes a cartridge-engaging piece 60 and a pinion-engaging piece 62, each injection molded in a single piece from plastic. Cartridge-engaging piece 60 has a square rod-shaped body 64 that extends in the axial direction to a proximal end 65, and a load distributing, disc-shaped portion 66 formed at the distal end of body 64. Four angularly spaced, contoured gussets 68 span body 64 and disc 66. Drive member pieces 60 and 62 are constrained by the interior surfaces of housing halves 36 and 38 to be axially translatable and rotatably fixed within the housing. Cartridge-engaging piece 60 is movable in the distal direction and prevented from proximal movement relative to the housing halves, while pinion-engaging piece 62 is clutchably connected to cartridge-engaging piece 60 to be moveable relative thereto in a proximal direction but not the distal direction. These one-way axial motions are achieved with ratchets in apparatus 20. In particular, body 64 of cartridge-engaging piece 60 includes a row of one-way ramping ratchet teeth 70 on two opposite sides of its four sides, which teeth continue uninterrupted along a portion of the axial length of the body. Ratchet teeth 70 are engaged by a pair of diametrically opposed, resilient tabs or pawls 72 integrally formed with housing half 38. Pawls 72 slide along and over teeth 70 when drive member piece 60 is advanced distally during use, but abut the transverse, proximal face of teeth 70 to prevent piece 60 from backing up in the proximal direction. Proximally of pawls 72, a pair of diametrically opposed resilient pawls 75 of pinion-engaging piece 62 also engage the same rows of ratchet teeth 70 on opposite sides of body 64. Pawls 75 slide along and over one or more teeth 70 when pinion-engaging piece 62 is moved proximally during pen cocking, but abut teeth 70 during the distal advancement of pinion-engaging piece 62 during injection, which abutting results in pinion-engaging piece 62 shifting distally the cartridge-engaging piece 60. The pitch or distance between the transverse face of each adjacent tooth 70 preferably is the distance piston 32 needs to be advanced to deliver the pen's fixed dose. In addition to its pawls 75, pinion-engaging piece 62 includes a plate-shaped body 77. A longitudinally extending rack 80 projects from one side of body 77. A pair of parallel, longitudinally extending ribs 82 project from the opposite side of body 77 and slidable receive rod-shaped body 64 therebetween. Another set of parallel rib portions 83 are shaped to slide along a ridge 45 formed on the interior surface 39 of housing half 38. A fixed or axially stationary rack 84 is included within pen proximal portion 24. Rack 84 is shown intergrally formed with housing half 38. Plunger member 54 allows a user to control the internal gear set of the apparatus to prepare pen 20 for injection, as well as to perform the injection. Plunger member 54 is formed of a multi-piece construction, including an input element 90, a button 92, and a force limiting biasing member 94. Button 92 is molded from plastic and externally sized and shaped to be rotatably fixed while slideable within housing 35. An internal hollow 93 of button 92 accommodates a biasing member 94 axially extending therethrough, and a series of longitudinally extending, internal ribs 95 of button 92 maintain the alignment of biasing member 94. The proximal end of button 92 is covered with a softer material shown at 97, which is formed via an overmolding process. A manually pullable grip portion 96 of button 92 is covered with the soft touch material and extends proximally of the housing 35. Flanges 98 laterally extend from the distal end of button 92 and, during pen cocking, abut inward lips 100 formed in housing halves 36, 38 to limit withdrawal of the plunger member from the housing. An indicating band 102 on button 92 is visible to a user when the button has been properly withdrawn to prepare pen 20 for medication delivery. Button 92 also includes a pair of diametrically opposed latches 101 at the distal ends of slot-defined fingers 103. Latches 101 inwardly project within hollow 93, and due to the resiliency of the fingers 103, snap-fit during manufacturing assembly over transversely extending shoulders 105 of the input element 90 to prevent axial, proximal withdrawal of the button 92 from the input element during operation. Plunger element 90 is made of injection molded plastic and is designed in conjunction with the housing to be rotatably fixed while slideable within housing 35. Plunger element 90 includes a cruciform-shaped protuberance 107 that proximally projects from a plate portion 108. Plate portion 108 is keyed to be rotatably fixed within the button, and includes the latchable shoulders 105. Protuberance 107 fits within the distal end of the force limiting biasing member 94 provided as a metal, helically coiled compression spring. The proximal end of biasing member 94 fits around a cruciform-shaped protuberance 109 formed on button 92 within hollow 93. Spring 94 is captured in a pre-stressed state between the latched plate portion 108 and the interior end of button 92, which pre-stressing is at least as large as forces the manufacturer expects users to apply on the plunger button during normal plunging to achieve proper pen operation. In one embodiment, in which a mechanical advantage of nominally ten to one is provided by the apparatus, the pre-stressing is in an amount of one pound. Thus, during normal plunging, spring 94 does not further compress and the button 92 and input element 90 shift as a unit and without relative axial motion. Coil spring 94 is also designed with sufficient spacing in its coiling, and with proper elastic properties, such that the spring, by compression, can accommodate movement of button 92 from the cocked position to the ready-to-be-cocked position without movement of plunger element 90, whereby spring 94 can absorb plunging forces that could damage the internal components. Plunger element 90 also includes a bar portion 110 and a block portion 114 which both project distally from plate portion 108. Near its distal end, bar portion 110 includes a laterally extending portion that serves as a U-shaped bearing or yoke 116. Yoke 116 extends and opens away from the pen axis. At its distal end, bar portion 110 terminates in an upstanding lip 117 with a ramped face 118. Lip 117 serves as a catch or hook of the apparatus locking mechanism. Yoke 116 receives the pin 120 of the gear set, which pin defines an axis about which the gear set partially revolves or pivots during use. Block portion 114 serves as a base to which a flexure or follower piece 122 of a partial-cocking-preventing mechanism is insert molded during manufacture. Follower piece 122 is made in one piece of a metal stamping and includes an apertured mounting plate 124 that is secured to block 114 during insert molding. A pair of resilient arms 126 longitudinally extend in parallel from mounting plate 124. Arms 126 serve as leaf springs and are spanned at their distal ends by web 128. A pawl 129 projects from web 128 toward housing half 36. Follower 122 directly engages a guide 135 of the partial-cocking-preventing mechanism. Follower arms 126 are closely backed by ribs 82 to better ensure that pawl 129 is not twisted out of a proper engagement with the guide during use. Referring also now to FIG. 12, guide 135 is integrally formed with the interior surface 37 of housing half 36 and includes a bar portion 138 having an angled, distal end 140 and an angled, proximal end 142. One longitudinally extending face of bar portion 138 provides a flat travel surface 146, and the opposite face of the bar portion 138 includes a travel surface 148 equipped with a plurality of ratchet teeth 150. Teeth 150 are engageable by pawl 129 to prevent distal movement of the plunger after only a partial withdrawal of the plunger in preparation for injection. Teeth 150 can be customized during manufacture to produce the desired number and volume of clicks during movement of the pawl over the row of teeth during use. For example, the provision of a large number of teeth, each having a relatively short height over which the pawl must be cammed outward, may result in clicks that are less distinct and similar in sound to a continuous, low volume buzz. Still further, instead of triangular teeth, the teeth may be lobe-shaped, with the indentation between lobes being where pawl 129 engages to prevent distal motion. Guide 135 further includes first and second abutment shoulders 152 and 154 molded into the housing. The partial-cocking-preventing mechanism in the shown embodiment provides an initial reluctance to pen cocking due to the sliding of pawl 129 over distal end 140, a tactile and audible notice of plunger movement, along with a prevention of plunger return prior to a complete dose preparation, due to the movement of pawl 129 over the row of teeth 150, an audible notice of complete dose preparation by the striking of abutment shoulder 152 by a distal end portion 130 of one resilient arm 126, an initial reluctance to injection due to the sliding of pawl 129 over proximal end 142, and an audible notice of injection completion by the striking of shoulder 154 by a distal end portion 131 of the other resilient arm 126. The gear set utilized in the injection pen is configured to convert plunger member motion of a first distance into drive member motion of a second distance less than the first distance. The gear set shown at 52 is made from a lightweight material such as plastic, and utilizes first and second sized pinions. The first or larger sized pinion 160 includes an arcuate section of external gear teeth 162 that mesh with rack 84. An arcuate section of gear teeth is all that is required due to the small angle of revolution of the pinion necessary for use of the shown pen, which small angle or partial roll is possible due to the nominally ten to one mechanical advantage provided by the shown gear ratio. The smaller sized pinion 166 has the same axis of rotation as pinion 160 and includes only an arcuate section of external gear teeth 168. Gear teeth 168 have a pitch diameter that is less than the pitch diameter of gear teeth 162. In the shown embodiment, such diameter is about 90% of the diameter of gear teeth 168, which ratio provides the nominally ten to one mechanical advantage. Smaller ratios may be employed, such as down to 50%, which realizes a two to one mechanical advantage, and larger ratios may alternatively be employed, such as realizing a ratio for a sixteen to one mechanical advantage. Gear teeth 168 meshably engage drive member rack 80, which rack is parallel to and disposed on the same side of the pinion axis as rack 84. Although pinion 160 and pinion 166 are shown integrally formed, these components can be separately formed and assembled together so as to be contrastable. Pinions 160 and 166 share a common axis of rotation. A pin or axle 120 is located at such axis and is shown integrally formed with the pinions. Pin 120 is sized and shaped to fit into, and pivot or partially rotate within, the opening of yoke 116 during use. During pen use, gear set 52 is shifted proximally and then distally in the following manner. The gear set is shifted axially with the plunger element 90 to which it is pinned as such plunger element is pulled out and subsequently plunged in. As gear set 52 moves proximally, the gear set rotates due to pinion 160 being in rolling engagement with fixed rack 84. As gear set 52 rotates, pinion 166 rolls along drive member rack 80, but also effectively pulls for a short distance the pinion-engaging piece 62 proximally relative to the cartridge-engaging piece 60 held by the pawls 72. During plunger element plunging, pinion 160 rolls backs along rack 84, and pinion 166 rolls along rack 80 while effectively pushing pinion-engaging piece 62 to advance cartridge-engaging piece 60 distally. Injection apparatus 20 includes a locking mechanism that prevents use of the apparatus after a final intended dose has been administered thereby. The locking mechanism automatically operates during the injection of such final dose to prevent the plunger from being withdrawn thereafter. The locking mechanism includes a generally C-shaped latching element, generally designated 180. Latching element 180 is formed in a single piece, such as a metal stamping, and includes a spring plate 182, a pair of installation flanges 184, and a latch lip 186. Flanges 184 depend from the distal edge of spring plate 182 and include lower ends 187. During pen manufacture, ends 187 press fit into complementary slots formed by wall 188 and barbed ribs 189 of the housing half 38 to assemble latching element 180 to the housing to be axially fixed relative thereto. Centrally located along the width of the plate 182 is a depending skid 190. Skid 190 has a lower surface 192 that is blade-shaped and longitudinally extends. Blade 192 directly contacts and slides along an axially extending, smooth surface 71 of cartridge-engaging piece 60. Skid 190 is formed by cutting and bending downward a portion of plate 182 during manufacture. An additional cut-out 194 opposite the opening formed by the bending downward of skid 190 results in a better symmetry of the plate portion 182 to aid in providing a more uniform springing effect during latching. Latch lip 186 depends from the proximal edge of spring plate 182 in the same direction as skid 190 depends, and is proximally spaced slightly from skid 190. Skid 190 is selected to be of such a height that its engagement with bar surface 71 results in spring plate 182 being deflected upward and away from its neutral position, whereby lip 186 is laterally spaced from the plunger member 54 extending thereunder, and in particular is spaced laterally from the hook 117 of bar portion 110. During initial use, blade 192 slides along the untoothed portion of the drive member at surface 71, with latch lip 186 being spaced from the plunger against the resiliency or spring-force provided by spring plate 182. When cartridge-engaging piece 60 is driven distally to complete its final injection, blade 192 slides off the proximal end 65 of smooth surface 71, allowing the resiliency of spring plate 182 to snap latch lip 186 downward. As latch lip 186 moves down, in the event that the plunger member 54 has already been fully shifted distally, the latch lip 186 fits proximally of the hook 117 of bar portion 110. In the event the shifting plunger has yet to have been shifted distally fully during the final dose administration, as the plunger motion continues the ramped face 118 engages latch lip 186 to temporarily cam latch lip 186 upward, and when the plunger is moved sufficiently distally, latch lip 186 then snaps down over hook 117. This latching of latch lip 186 with hook 117 prevents any further proximal motion of bar portion 110, and thereby of the entire plunger member 54. Although shown directly engaging input element 90, the latching element may engage other portions of the drive mechanism within the scope of the invention. Referring now to FIG. 13, there is shown an exploded, perspective view of another embodiment of a medication dispensing apparatus of the present invention. The apparatus, generally designated 220, is substantially similar to apparatus 20, with some differences being identified below. In particular, the locking mechanism preventing use after an administration of a final intended dose includes a generally L-shaped latching element, generally designated 225, formed in a single piece, such as a metal stamping. The spring plate 227 of latching element 225 includes a centered aperture 230 that defines webs 232 and 234. Depending from spring plate 227 along the proximal edge of aperture 230 is a transversely extending skid 236 having an upwardly curved lower end 238. Generally elliptical slots 242 formed through the spring plate form a pair of rims 240 that each include a portion that upwardly projects beyond the top of the spring plate. Rims 240 project from the spring plate in a direction opposite to the direction skid 236 projects. Rims 240 are proximally spaced from skid 236. The shown rims 240 serve as a pair of latching lips each providing a hook-contacting surface that is larger than that formed merely by the small thickness of the shown spring plate, thereby better distributing loading. The proximal edge of spring plate 227 is upturned at 244 to promote the spring plate being cammed over the locking mechanism hooks as may be necessary. Skid 236 still is of a height that its engagement with the bar surface 71 results in spring plate 227 being directed upward and away from its neutral position, whereby rims 240 are spaced from the apparatus plunger disposed thereunder, and in particular from the bar portion hooks. In conjunction with this modified latching element, the plunger element 260 includes a pair of spaced, parallel bar portions 262, 264 that project distally from a plate portion 266. Each of bar portions 262, 264 includes a lip 266, with a ramped face 267, to serve as a rim-engaging hook of the locking mechanism when inserted through the spring plate openings 240. Only one of the bar portions, namely bar 262, is provided with the yoke for mounting the gear set 270. The plunger button of the embodiment of FIG. 13 is formed of two pieces, namely 274 and 276, which are fixedly secured together during manufacturing assembly. Piece 274 is a different color than piece 276, and the pieces 274 and 276 are sized such that the proximal end region of piece 274 serves as a colored indicating band that is visible to a user when the plunger button is fully withdrawn to prepare the pen for delivery. The embodiment of FIG. 13 has a mechanical advantage of just over seven, as a ratio of the gear pitch diameters of gear set 270 is 86%. The cartridge engaging piece 280 may be designed with ratchet teeth that are adapted for an initial shipping/storage of a ready-to-be-cocked apparatus in which, while pawls 282 are each similarly situated at the start of their respective ratchet tooth (i.e. proximate the transverse face of the distally adjacent tooth), both anti-back-up pawls 284 are similarly partially cammed outward by their engagement with a middle length portion of different ratchet teeth. These different ratchet teeth so initially engaged by pawls 284 have a shallower slope and therefore lesser height, as measured from the longitudinal axis of the apparatus, than the other teeth in the row, thereby reducing the stress on pawls 284 prior to the first use of the apparatus by the user. In order to possibly account for a single test cycle by the manufacturer during assembly, two adjacent lesser height teeth in each row for engagement with pawls 284 may be provided. While this invention has been shown and described as having preferred designs, the present invention may be modified within the spirit and scope of this disclosure. For example, other forms of drive systems, including but not limited to drive systems providing mechanical advantage using rack and pinion designs, possibly such as disclosed in the materials herein incorporated by reference, may be utilized. For example, a gear set may have pinned to its axle an output member which engages the cartridge piston. Such gear set may have one arc of gear teeth that engage a housing rack, and another arc of gear teeth that engage a plunger rack, which racks are positioned on opposite sides of the gear set's axle. Such arcs of gear teeth may have a common pitch diameter, or the housing rack-engaging gear teeth may have a pitch diameter which is smaller or larger than the plunger rack-engaging gear teeth. Still further, in another version the gear set may be pinned to the housing. A plunger rack of the system may engage gear teeth of the gear set having a larger pitch diameter, and a rack of the output member which engages the cartridge piston may engage teeth of the gear set having a smaller pitch diameter. Still further, for an unpinned or rolling gear set, a plunger rack may engage gear teeth with a first pitch diameter, a rack of an output member which engages the cartridge piston may engage gear teeth with a smaller pitch diameter, and a housing rack, which is positioned on the opposite side of the gear set's center from the plunger and output racks, may engage gear teeth with a pitch diameter that is the same or smaller than that of teeth engaging the plunger rack. Still further, in a rolling gear set design related to the materials herein incorporated by reference, the plunger rack may engage teeth with a smaller pitch diameter than the pitch diameter of gear teeth/engaging the housing rack. This application is therefore intended to cover any variations, uses or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains.

<SOH> BACKGROUND OF THE INVENTION <EOH>The present invention pertains to medication dispensing devices, and, in particular, to a portable medication dispensing device such as an injector pen. Patients suffering from a number of different diseases frequently must inject themselves with medication. To allow a person to conveniently and accurately self-administer medicine, a variety of devices broadly known as injector pens or injection pens have been developed. Generally, these pens are equipped with a cartridge including a piston and containing a multi-dose quantity of liquid medication. A drive member, extending from within a base of the injector pen and operably connected with typically more rearward mechanisms of the pen that control drive member motion, is movable forward to advance the piston in the cartridge in such a manner to dispense the contained medication from an outlet at the opposite cartridge end, typically through a needle that penetrates a stopper at that opposite end. In disposable pens, after a pen has been utilized to exhaust the supply of medication within the cartridge, the entire pen is discarded by a user, who then begins using a new replacement pen. In reusable pens, after a pen has been utilized to exhaust the supply of medication within the cartridge, the pen is disassembled to allow replacement of the spent cartridge with a fresh cartridge, and then the pen is reassembled for its subsequent use. Some injector pens allow a dose to be set that is larger than the amount of useable medicine remaining in the pen. While some users may find such settability undesirable, providing an insufficient remaining dose indicator may not be practical in all cases, such as due to it complicating the pen design. Still further, a shortcoming with some injector pens is that the design platform on which they are based may not allow a manufacturer sufficient options as to the mechanical advantage to provide, such as a mechanical advantage that can be very small in order to readily inject a large volume dose, or which mechanical advantage can be quite large so as to deliver a small volume dose with a suitable plunger travel. Thus, it would be desirable to provide an apparatus that can overcome one or more of these and other shortcomings of the prior art.

<SOH> BRIEF SUMMARY OF THE INVENTION <EOH>In one form thereof, the present invention provides a medication dispensing apparatus including a housing, a drive member within the housing and movable in a distal direction, a fluid container defining a medicine-filled reservoir with a movable piston at one end and an outlet at the other end, the piston being engageable by the drive member to be advanced toward the outlet a distance equal to a distal movement of the drive member when the drive member is moved distally, a means for driving the drive member distally, and a latching element including a latching lip and a skid. The drive member includes an axially extending, skid-engaging surface along which the skid is slidable as the drive member passes distally during advancement. The skid-engaging surface has an axial length and a proximal end, and the drive member along the axial length is structured and arranged with the skid so as to maintain the latching lip against a spring force in a first position free of the driving means during dose preparing and injecting prior to a final dose administration. The skid-engaging surface shifts distally of the skid such that the skid passes beyond the proximal end upon administration of a final dose, whereby the latching lip is urged by the spring force from the first position to a second position to physically lock the driving means to prevent further dose preparing and injecting. One advantage of the present invention is that a medication dispensing apparatus can be provided with an uncomplicated and robust mechanism for automatically locking the apparatus to prevent further use after a final dose of the apparatus has been administered. Yet another advantage of the present invention is that a medication dispensing apparatus can be provided which is readily adaptable by the manufacturer to furnish a mechanical advantage during dose administration selected from a wide range of such advantages, such as a small advantage of about two for a large volume dose, up to a large advantage of about sixteen for a small volume dose. Another advantage of the present invention is that a medication dispensing apparatus can be provided which is internally configured to utilize space efficiently to allow for a compact design that contributes to a small and symmetrical design-of the apparatus.

20060918

20090414

20070823

64275.0

A61M5315

CARPENTER, WILLIAM R

MEDICATION DISPENSING APPARATUS WITH SPRING-DRIVEN LOCKING FEATURE ENABLED BY ADMINISTRATION OF FINAL DOSE

UNDISCOUNTED

ACCEPTED

A61M

ACCEPTED

Information terminal, and event notifying method

An information terminal of the present invention aims at informing the user of an occurrence of an event during the reproduction of contents without an unexpected feeling. An information terminal of the present invention, includes a contents reproducing unit 10 for reproducing contents, a contents reproducing unit 20 for informing an occurrence of an event by reproducing the contents, a superposing unit 70 for superposing respective outputs of the contents reproducing unit 10, 20, and a controlling unit 50 for causing an information of the occurrence of the event and a superposition of respective outputs of the contents reproducing unit 10, 20 to execute in a previously set reproducing procedure.

1. An information terminal, comprising: a reproducing unit that reproduces contents; an informing unit that informs an occurrence of an event; a superposing unit that superposes an output of the reproducing unit and an output of the informing unit; and a controlling unit that causes an information of the occurrence of the event and a superposition of the output of the reproducing unit and the output of the informing unit to execute in a previously set reproducing procedure. 2. The information terminal according to claim 1, further comprising: a storing unit that stores a plurality of the reproducing procedures; and an extracting unit that extracts meta information to select the reproducing procedure from the contents, wherein the controlling unit causes the superposition of the output of the reproducing unit and the output of the informing unit and the information of the occurrence of the event to execute in the reproducing procedure selected based on the extracted meta information. 3. The information terminal according to claim 1, further comprising: a storing unit that stores a plurality of the reproducing procedures; and an acquiring unit that acquires data that is corresponded to the contents, wherein the controlling unit causes the superposition of the output of the reproducing unit and the output of the informing unit and the information of the occurrence of the event to execute in the reproducing procedure selected based on the acquired information. 4. The information terminal according to claim 1, further comprising: a storing unit that stores a plurality of the reproducing procedures; and a sensing unit that senses a state of the terminal, wherein the controlling unit causes the superposition of the output of the reproducing unit and the output of the informing unit and the information of the occurrence of the event to execute in the reproducing procedure selected based on the sensed state of the terminal. 5. A method of informing an event that occurs during reproduction of contents, causing a superposition of an output of a reproducing unit and a output of an informing unit and an information of an occurrence of an event to execute in a previously set reproducing procedure. 6. The method of informing the event according to claim 5, wherein the reproducing procedure is selected based on meta information of the contents. 7. The method of informing the event according to claim 5, wherein the reproducing procedure is selected based on information that is corresponded to the contents. 8. The method of informing the event according to claim 5, wherein the reproducing procedure is selected based on a state of a terminal.

TECHNICAL FIELD The present invention relates to an information terminal having a function of reproducing various contents such as a music, a moving picture, a television broadcast, and the like and, more particularly, an information terminal characterized in that a contents reproducing operation is controlled when an event such as a phone call, or the like takes place while the contents are being reproduced, and a method of informing an event. BACKGROUND ART In recent years, on account of a size reduction and a capacity increase of the memory and an improvement in the sound compressing technology, the mobile terminal such as the cellular phone, or the like is also able to reproduce conveniently various contents such as the music, the moving picture, the television broadcast, and the like. In this situation it becomes an important control element to switch an output of an informing sound, or the like and a reproduced output of the contents and adjust the balance between them when the event occurs. For example, the information terminal device, the cellular phone, and the like, which can control adequately these outputs at a time of receiving a call or speaking on the phone, have been proposed (see Patent Literature 1, for example). Patent Literature 1: JP-A-2003-258988 (Pages 4 to 7, FIG. 1) DISCLOSURE OF THE INVENTION Problems that the Invention is to Solve In the information terminal device disclosed in Patent Literature 1, the balance between a reproducing sound of the contents and a speaking sound is changed into a previously set value at a time of incoming of a phone call. With this information terminal device, the user can speak satisfactorily over the phone while reproducing the audio, for example. However, in the information terminal device in the prior art, since a reduction in a reproduced sound volume of the contents and an increase in a sound volume of the speaking sound are made suddenly when the phone call comes in, for example, the user of the device has an unexpected feeling such that the user is surprised at a sudden change in balance, or the like. Also, the incoming call of the phone made always by the same bell or phone melody irrespective of the type of reproduced contents is the uniform information and lacks its power of expression, and has its poor entertaining faculty. It is an object of the present invention to provide an information terminal capable of informing the user of an occurrence of an event during the reproduction of contents without an unexpected feeling and a method of informing an event. Also, it is another object of the present invention to provide an information terminal with its high entertaining faculty, capable of informing an occurrence of an event in various ways by its excellent powers of expression and a method of informing an event. Means for Solving the Problems An information terminal of the present invention, includes a reproducing unit for reproducing contents; an informing unit for informing an occurrence of an event; a superposing unit for superposing an output of the reproducing unit and an output of the informing unit; and a controlling unit for causing an information of the occurrence of the event and a superposition of the output of the reproducing unit and the output of the informing unit to execute in a previously set reproducing procedure. Also, a method of informing an event that occurs during reproduction of contents, the method causes a superposition of an output of a reproducing unit and a output of an informing unit and an information of an occurrence of an event to execute in a previously set reproducing procedure. According to this configuration, the reproduction of contents and the information of an occurrence of an event are carried out in previously set reproducing procedures. Therefore, it is possible to inform the user of an occurrence of an event during the reproduction of contents without an unexpected feeling. Also, the information terminal of the present invention further includes a storing unit for storing the reproducing procedure in plural; and an extracting unit for extracting meta information to select the reproducing procedure from the contents; wherein the controlling unit causes the superposition of the output of the reproducing unit and the output of the informing unit and the information of the occurrence of the event to execute in the reproducing procedure selected based on the extracted meta information. Also, the information terminal of the present invention further includes a storing unit for storing the reproducing procedure in plural; and an acquiring unit for acquiring data that is corresponded to the contents; wherein the controlling unit causes the superposition of the output of the reproducing unit and the output of the informing unit and the information of the occurrence of the event to execute in the reproducing procedure selected based on the acquired information. Also, the information terminal of the present invention further includes a storing unit for storing the reproducing procedure in plural; and a sensing unit for sensing a terminal state; wherein the controlling unit causes the superposition of the output of the reproducing unit and the output of the informing unit and the information of the occurrence of the event to execute in the reproducing procedure selected based on the sensed terminal state. Also, in the event informing method of the present invention, a reproducing procedure is selected based on meta information of the contents. Also, in the event informing method of the present invention, a reproducing procedure is selected based on information that is corresponded to the contents. Also, in the event informing method of the present invention, a reproducing procedure is selected based on a terminal state. According to this configuration, the optimum reproducing procedure can be selected from plural reproducing procedures in response to the contents being reproduced. Therefore, it is possible to provide the information terminal with high entertaining faculty, capable of informing an occurrence of an event in various ways by its excellent powers of expression. Advantages of the Invention According to the present invention, the reproduction of contents and the information of an occurrence of an event are carried out in previously set reproducing procedures. Therefore, it is feasible to inform the user of the occurrence of the event during the reproduction of contents without an unexpected feeling. BRIEF DESCRIPTION OF THE DRAWINGS [FIG. 1] A view showing a schematic internal configuration of an information terminal in an embodiment of the present invention. [FIG. 2] A flowchart showing the controlling operation procedure performed when an event is sensed during the reproduction of contents, in the information terminal in the embodiment of the present invention. [FIG. 3] A view showing a detailed internal configuration of the information terminal in the embodiment of the present invention. [FIG. 4] A sequence diagram showing the contents reproduction controlling operation procedure performed when a phone call is sensed during the reproduction of contents, in the information terminal in the embodiment of the present invention. [FIG. 5] A sequence diagram showing the contents reproduction controlling operation procedure performed when the phone call is sensed during the reproduction of contents, in the information terminal in the embodiment of the present invention. [FIG. 6] A sequence diagram showing the contents reproduction controlling operation procedure performed when the phone call is sensed during the reproduction of contents, in the information terminal in the embodiment of the present invention. [FIG. 7] A sequence diagram showing the contents reproduction controlling operation procedure performed when the phone call is sensed during the reproduction of contents, in the information terminal in the embodiment of the present invention. [FIG. 8] A sequence diagram showing the contents reproduction controlling operation procedure performed when the phone call is sensed during the reproduction of contents, in the information terminal in the embodiment of the present invention. [FIG. 9] A sequence diagram showing the contents reproduction controlling operation procedure performed when the phone call is sensed during the reproduction of contents, in the information terminal in the embodiment of the present invention. [FIG. 10] A sequence diagram showing the contents reproduction controlling operation procedure performed when the phone call is sensed during the reproduction of contents, in the information terminal in the embodiment of the present invention. [FIG. 11] A view showing an example of a description format of the character data inserted into contents data. [FIG. 12] A view showing an example of a description format of the meta information. [FIG. 13] A view showing a reference example of a control procedure table. [FIG. 14] A timing chart showing contents of the contents reproduction controlling operation executed based on scenario information separately in terms of the video output and the sound output. [FIG. 15] A timing chart showing contents of the contents reproduction controlling operation executed based on scenario information every control track. [FIG. 16] A timing chart showing contents of the contents reproduction controlling operation executed based on scenario information every control track. [FIG. 17] A view showing schematically respective changes of an image displayed on LCD and a sound level output to a head set on a timing chart until the on-hook is sensed after the phone call is sensed. [FIG. 18] A timing chart showing contents of the contents reproduction controlling operation executed based on scenario information separately in terms of the video output and the sound output (informing contents are not reproduced). DESIGNATION OF REFERENCE NUMERALS 10 first contents reproducing unit 11 TV reproducing unit 12 TV tuner 13 demodulating unit 14 antenna 20 second contents reproducing unit 21 moving picture reproducing unit 22 moving picture reading unit 23 moving picture storing unit 25 image reproducing unit 26 image reading unit 27 image storing unit 30 incoming call/alarm contents reproducing unit 31 ringtone reproducing unit 32 ringtone reading unit 33 ringtone storing unit 40 clocking unit 50 controlling unit 51 CPU 52 controlling procedure holding unit 53 meta information extracting unit 54 phone book 55 key input sensing unit 60 event sensing unit 61 incoming call sensing unit 70 superposing unit 80 communicating unit 81 demodulating unit 82 decoder (audio) 83 encoder (audio) 84 modulating unit 90 providing unit 91 LCD 92 head set 101 demultiplexer 102 decoder (audio) 103 sound buffer 104 decoder (video) 105 frame buffer 106 decoder (data) 201 demultiplexer 202 decoder (audio) 203 sound buffer 204 decoder (video) 205 frame buffer 206 decoder (image) 207 frame buffer 301 sound buffer BEST MODE FOR CARRYING OUT THE INVENTION An information terminal according to an embodiment of the present invention will be explained with reference to the accompanying drawings hereinafter. The same reference symbols are affixed to the elements having the same function throughout all figures used to explain the embodiment, and their redundant explanation will not be repeated herein. FIG. 1 is a view showing a schematic internal configuration of an information terminal in an embodiment of the present invention. The information terminal includes a first contents reproducing unit 10, a second contents reproducing unit 20, an incoming call/alarm contents reproducing unit 30, a clocking unit 40, a controlling unit 50, an event sensing unit 60, a superposing unit 70, a communicating unit 80, and an providing unit 90. The first contents reproducing unit 10 is a portion for reproducing audio-visual contents such as the music, movie, TV, and the like, and includes a decoder, a television tuner, and the like used for coded/compressed data. The second contents reproducing unit 20 is a portion for reproducing informing contents that are different from incoming call/alarm informing contents described later. The incoming call/alarm contents reproducing unit 30 is a reproducing portion for informing the user of the information terminal of the incoming call/alarm, and reproduces sequence sound, audio, moving picture, animation, and the like. The clocking unit 40 measures a time, and informs the controlling unit 50 and the superposing unit 70 of time information regarding the reproduction of the contents. The controlling unit 50 supervises/controls the overall operation of the information terminal concerning the sensing/informing event such as a control regarding the play/stop of contents, operation controls (timing, superposing parameter, pointing of the type of superposition, etc.) of the superposing unit 70, and the like. The controlling unit 50 is connected to a controlling procedure holding unit 52, and a meta information extracting unit 53. The controlling procedure holding unit 52 stores plural pieces of scenario information that describe reproducing procedures of the contents reproduction and the event information. The meta information extracting unit 53 extracts the meta information, which is used to designate one of scenario information stored in the controlling procedure holding unit 52, from the contents data that is being reproduced by the first contents reproducing unit 10. The event sensing unit 60 senses an event such as a phone call, an alarm, or the like and then informs the controlling unit 50 of the event. The superposing unit 70 superposes visually and acoustically outputs of the first contents reproducing unit 10 and the second contents reproducing unit 20, an output of the incoming call/alarm contents reproducing unit 30, and the speaking sound. The communicating unit 80 acts as a radio communication unit for controlling an outgoing call and an incoming call of the phone in the information terminal, and holds a communication with a radio base station constituting the public radio telephone network to transmit/receive the phone conversation, the electronic mail, and the like. Here, the publicly known approach may be employed in the radio communication and therefore explanation about the detailed inner configuration of the communicating unit 80 and respective functions implemented by this communicating unit will be omitted herein. The providing unit 90 provides the superposed reproduced output to the user of the information terminal via a display like LCD, a speaker, or the like. FIG. 2 is a flowchart showing the controlling operation procedure performed when an event is sensed during the reproduction of contents, in the information terminal in the embodiment of the present invention. At first, while the contents data are being reproduced by the first contents reproducing unit 10 (step S101), the event sensing unit 60 senses the event such as a phone call, an alarm, or the like (step S102). Then, the controlling unit 50 grasps the meta information that the meta information extracting unit 53 extracts from the contents data being reproduced at that time (step S103). The meta information contains type of the contents being reproduced, information indicating the scenario information, and the like. Therefore, the controlling unit 50 selects the scenario information based on the meta information, and reads the designated scenario information from the controlling procedure holding unit 52 (step S104). For example, when the contents being reproduced at that time corresponds to the sports broadcast of the TV broadcast, the scenario information corresponding to the meta information “sports broadcast” of the contents is selected. The controlling unit 50 controls the superposition of the output of the first contents reproducing unit 10 and the output of the second contents reproducing unit 20 in time series based on the read scenario information and time information acquired from the clocking unit 40 (step S105). For instance, the controlling unit fades out the output of the first contents reproducing unit 10 and also fades in the output of the second contents reproducing unit 20 in parallel. Then, before the scenario is ended (step S106), the event sensing unit 60 senses the event, for example, the phone conversation initiated by the phone call is ended, or the like (step S107). Then, the controlling unit 50 controls again the superposition of the output of the first contents reproducing unit 10 and the output of the second contents reproducing unit 20 in time series to restore the first and second contents reproducing unit into their original contents reproducing states (step S105). In this case, particular examples of “control a reproduced output” in step S105 will be explained in detail in Examples later. In this manner, when the event is sensed, the superposition of the reproduced output of the first contents reproducing unit and the reproduced output of the second contents reproducing unit is changed gradually. Therefore, it is possible to inform the user of the occurrence of the event without an unexpected feeling. Also, the event information whose powers of expression is excellent and whose entertaining faculty is high can be attained by selecting the optimum scenario information based on the meta information of the contents being reproduced. Next, an internal configuration of the information terminal, into which a TV reproducing unit as an example of the first contents reproducing unit 10 in FIG. 1 and an incoming call sensing unit of the phone as an example of the event sensing unit 60 are installed, and its reproduced output controlling operation taken when the phone call comes in during the reproduction of contents will be explained concretely hereunder. FIG. 3 is a view showing an internal configuration of a cellular phone terminal in the embodiment of the present invention. The cellular phone terminal includes a TV reproducing unit 11, a moving picture reproducing unit 21, an image reproducing unit 25, a ringtone reproducing unit 31, a clocking unit 40, a controlling unit 50, an incoming call sensing unit 61, a superposing unit 70, a communicating unit 80, an LCD 91, and a head set 92. The TV reproducing unit 11 is an example of the first contents reproducing unit 10 in FIG. 1, and is configured by a TV tuner 12, a demodulating unit 13, an antenna 14, and the like. The TV tuner 12 receives a radio wave of the TV broadcast via the antenna 14, and the demodulating unit 13 demodulates a received radio wave. The TV reproducing unit 11 causes a demultiplexer 101 to demultiplex the demodulated stream and then causes audio, video, and data decoders to decode demultiplexed signals respectively. The decoded audio and video data are output to the superposing unit 70 described later via buffers. The data decoded by the data decoder 106 are output to a meta information extracting unit 53 described later. The moving picture reproducing unit 21 and the image reproducing unit 25 are given as an example of the second contents reproducing unit 20 in FIG. 1. The moving picture reproducing unit 21 is configured by a moving picture reading unit 22, a moving picture storing unit 23, and the like, and the image reproducing unit 25 is configured by an image reading unit 26, an image storing unit 27, and the like. The moving picture reproducing unit 21 causes a demultiplexer 201 to demultiplex the moving picture that the moving picture reading unit 22 reads from the moving picture storing unit 23 and output the demultiplexed moving picture to the superposing unit 70 described later via buffers. The image reproducing unit 25 causes a decoder 206 to decode the image data that image reading unit 26 reads from the image storing unit 27 and output the demultiplexed moving picture to the superposing unit 70 described later via a buffer. The ringtone reproducing unit 31 is given as an example of the incoming call/alarm contents reproducing unit 30 in FIG. 1. This ringtone reproducing unit is configured by a ringtone reading unit 32, a ringtone storing unit 33, and the like, and executes the reproduction of the ringtone when the phone call comes in. The ringtone data that the ringtone reading unit 32 reads from the ringtone storing unit 33 are output to the superposing unit 70 described later via a buffer. The clocking unit 40 and the controlling unit 50 have the same function as the clocking unit and the controlling unit in FIG. 1 respectively. The controlling unit 50 is realized through software by a control program executed by a CPU 51. Also, the controlling procedure holding unit 52 and the meta information extracting unit 53 are connected to the controlling unit 50. The incoming call sensing unit 61 is given as an example of the event sensing unit 60 in FIG. 1, and senses the incoming call of the phone herein. The superposing unit 70 and the communicating unit 80 have the same function as the superposing unit and the communicating unit in FIG. 1 respectively. A demodulating unit 81, an audio decoder 82, an audio encoder 83 and a modulating unit 84 are provided between the communicating unit 80 and the superposing unit 70. The LCD 91 and the head set 92 are given as an example of the providing unit 90 in FIG. 1. The LCD 91 displays the image of the contents superposed by the superposing unit 70, and the like. Also, the head set 92 outputs the sound of the contents superposed by the superposing unit 70, and the like from a speaker portion. As a result, the user of the information terminal can view and listen the informing contents, and the like via the screen of the LCD 91 and the sound output of the head set 92. FIG. 4 to FIG. 10 are sequence diagrams showing the contents reproduction controlling operation procedures performed when a phone call is sensed during the reproduction of contents, in the information terminal in the embodiment of the present invention. At first, the TV reproducing unit 11 outputs periodically the stream data of the received TV broadcast to the buffers connected to the superposing unit 70 while the user of this information terminal is viewing the TV broadcast (step S201). Also, the meta information extracting unit 53 extracts periodically the meta information from character data of the received TV broadcast reception data (step S202), and informs the meta information of the CPU 51 (step S203). FIG. 11 is a view showing an example of a description format of the character data inserted into contents data (i.e., TV broadcast reception data in the present embodiment). The meta information extracting unit 53 extracts the meta information from the character data. FIG. 12 is a view showing an example of a description format of the meta information. In FIG. 12, since the user is looking and listening the night game broadcast program, the meta information in the genre “sports” is extracted. When the incoming call sensing unit 61 senses the phone call via the communicating unit 80 during the reproduction of the television broadcast (step S204), it issues the incoming call notice to the CPU 51 (step S205). The CPU 51 looks up phone number data stored in the phone book 54 (step S206), and grasps that the phone call is issued from the sender who belongs to the “friend” group (step S207). The CPU 51 requests the clocking unit 40 to inform present time information (step S208), and acquires the present time information (step S209). Then, the CPU 51 accesses the controlling procedure holding unit 52 (step S210), and searches and acquires the appropriate scenario information (step S211). As the search conditions in this case, the genre is “sports”, the sender group is “friend”, and the present time is “Oct. 4, 2004 20:0502”, and the different scenario information is selected according to the search conditions. In more detail, since the controlling procedure holding unit 52 holds a control procedure table that correlates the search conditions with the scenario information uniquely, the scenario information can be searched by looking up this table. FIG. 13 is a view showing a reference example of the control procedure table. For example, when the genre of the extracted meta information “sports broadcast” is “sports”, a table “script table_sports” is referred to. In this table, the scenario information are classified under the search items of the sender group and the arrival period. Therefore, it is understood that in this case a “script 2” is selected as the appropriate scenario information. Next, explanation goes to a sequence diagram in FIG. 5. The CPU 51 instructs the controlling unit 50 to start the control (step S212), and then the controlling unit 50 initializes a timer of the clocking unit 40 (step S213). Subsequently the controlling unit starts the contents reproduction controlling operation according to the “script 2”. At first, the controlling unit instructs the image reproducing unit 25 to write the image (step S214), and then the image reading unit 26 acquires the image data from the image storing unit 27 (steps S215, S216). The image reproducing unit 25 outputs the acquired image data into the buffer connected to the superposing unit 70 (step S217), and notifies the controlling unit 50 of the write completion (step S218). When the controlling unit 50 instructs the superposing unit 70 to switch the image (step S219), the display of the LCD 91 is changed from the TV video of the sports broadcast shown in FIG. 5(a) to the image shown in FIG. 5(b). Then, the controlling unit causes the clocking unit 40 to start a count of a predetermined time (step S220), and then instructs the moving picture reproducing unit 21 to standby the moving picture (step S221). The moving picture reading unit 22 acquires the moving picture from the moving picture storing unit 23 (steps S222, S223). The moving picture reproducing unit 21 outputs the acquired moving picture into the buffer connected to the superposing unit 70 (step S224), and notifies the controlling unit 50 of the standby completion (step S225). Next, explanation goes to a sequence diagram in FIG. 6. The controlling unit 50 decreases a sound gain of the TV reproducing unit 11 stepwise in a predetermined timer period, and fades out the sound of the TV broadcast (steps S227 to S241). When the controlling unit 50 instructs the superposing unit 70 to switch the image (step S242) and also instructs the moving picture reproducing unit 21 to start the reproduction of the moving picture (step S243), the moving picture reproducing unit 21 starts the reproduction of the moving picture (step S244) and notifies the controlling unit 50 of the reproduction start (step S245). The display of the LCD 91 is changed from the image shown in FIG. 6(a) to the video shown in FIG. 6(b). Next, explanation goes to a sequence diagram in FIG. 7. When the controlling unit 50 instructs the ringtone reproducing unit 31 to start the reproduction of the ringtone (step S247), the ringtone reading unit 32 acquires the ringtone data from the ringtone storing unit 33 (steps S248, S249). The ringtone reproducing unit 31 outputs the acquired ringtone data to the buffer connected to the superposing unit 70 (step S250), and also notifies the controlling unit 50 of the ringtone reproduction start (step S251). Then, the controlling unit 50 gives the instruction as to the superposition balance of reproduced outputs among the TV reproducing unit 11, the moving picture reproducing unit 21, and the ringtone reproducing unit 31 to the superposing unit 70. In this situation, the output of the moving picture reproducing unit 21 is set to 100%. But subsequently the controlling unit 50 changes stepwise the balance of the reproduced outputs in a predetermined period, and cross fades the reproduced output from the contents of the moving picture reproducing unit 21 to the television broadcast of the TV reproducing unit 11 (steps S254 to S259). Next, explanation goes to a sequence diagram in FIG. 8. The controlling unit 50 changes stepwise the superposition balance of the reproduced outputs in the same procedures as those in steps S254 to S259, and sets the output of the TV reproducing unit 11 to 100% finally (steps S260 to S266). Then, the controlling unit 50 stops the output of the moving picture reproducing unit 21 (steps S267, S268). Therefore, on the display of the LCD 91, the contents reproduced video of the moving picture reproducing unit 21 shown in FIG. 7(a) fades out gradually as shown in FIG. 7(b), while the received video of the TV broadcast fades in. Also, the sounds of the TV broadcast and the ringtone fade in in the head set 92. In the state shown in FIG. 8(a), an output level of the ringtone is set to 100% and an output level of the TV broadcast is set to 50%. Next, explanation goes to a sequence diagram in FIG. 9. When the user who knows the phone call pushes an off-hook key, the key input sensing unit 55 senses the key pushing (step S301). The CPU 51 notifies the controlling unit 50 of the key pushing (step S302), and then the controlling unit 50 causes the ringtone reproducing unit 31 to stop the reproduction (steps S303, S304). Also, the controlling unit 50 instructs the superposing unit 70 to set a gain of the speaking sound (step S305). In this state, the video of the TV broadcast is displayed on the LCD 91, and the sound in which the TV broadcast sound (50%) and the speaking sound (100%) are superposed is output into the head set 92. Then, the user pushes the on-hook key after he or she ends the phone conversation, the key input sensing unit 55 senses the key pushing (step S401). The CPU 51 notifies the controlling unit 50 of the key pushing (step S402), and the controlling unit 50 turns off a gain setting of the speaking sound (step S403). Subsequently the controlling unit 50 increases stepwise gains of the received video and the sound of the TV broadcast in a predetermined period in the opposite procedures to those described above (steps S404 to S406). Next, explanation goes to a sequence diagram in FIG. 10. The controlling unit 50 increases the gains in the same procedures as those in steps S404 to S406, so that both the video and sound reproduced outputs of the TV reproducing unit 11 are set to 100% finally (steps S407 to S415). With the above, the contents reproduction controlling operations performed when the phone call is sensed during the reproduction of the contents are ended. In the above sequence, the procedures set forth in step S212 to step S268 correspond to the “reproduced output control” process (step S105) in a flowchart in FIG. 2. Also, the procedures set forth in step S403 to step S415 correspond to the “reproduced output control” process in step S105. FIG. 14 is a timing chart showing contents of the contents reproduction controlling operation executed based on the scenario information described as the above “script 2” separately in terms of the video output and the sound output. Also, FIGS. 15 and 16 are timing charts showing contents of the contents reproduction controlling operation executed based on the scenario information described similarly as the “script 2” every control track. Also, FIG. 17 is a view showing schematically respective changes of an image displayed on LCD and a sound level output to a head set on a timing chart until the on-hook is sensed after the phone call is sensed. After the phone call comes in, the video of the TV broadcast on the display is transferred to the image and the moving picture to inform the incoming call, and the sound of the TV broadcast fades out and also the sound of the moving picture or the ringtone fades in. The speaking sound that has the maximum output during the conversation stops its output at the same time when the conversation is ended, and the sound of the TV broadcast fades in and is restored. By the way, when the scenario information by which the reproduction of the informing contents is not executed at a time of incoming of the phone call is selected, the video output and the sound output are given as shown in a timing chart shown in FIG. 18. In an example in FIG. 18, the video of the TV broadcast is output as it is after the phone call comes in, but the scenario is set such that the sounds of the TV broadcast and the ringtone cross fade. Therefore, unless the informing contents are not reproduced, an unexpected feeling caused at a time of incoming of the phone call can be reduced conspicuously rather than the prior art. In the above embodiment, preferably the scenario information indicating the control procedures of the contents reproduction controlling operation should be added or updated by executing the download operation of the information terminal, reading the data from the removable media, or the like. In addition, infrared communication, Bluetooth communication, KIOSK terminal, TV data broadcast, and others may be utilized. Also, in the above embodiment, an approach of executing a time management by strictly counting a time by a counter of the clocking unit is employed. In this case, instead of the clocking unit, a description to cause a time elapse may be inserted into the scenario information and then the contents of description may be executed sequentially by the controlling unit. Also, a description of time may be inserted into the scenario information and then the contents of description may be executed by the superposing unit. For example, the instruction having the contents “The TV sound fades out from 100% to 0% within 2 second.” may be transferred from the controlling unit to the superposing unit, and then the superposing unit executes the instruction based on a clocking function built in the superposing unit. Also, in the above embodiment, an approach of extracting the meta information from the character data contained in the contents being reproduced may be employed. In this case, such a configuration may be employed that the meta information contained in file name of the contents, file form time, file update time, file size, file type, file extension, file format, or file header, the meta information contained in another file, or the meta information acquired from the external system (network, broadcast, storage media, or the like) based on the above may be extracted. Also, the selection of the scenario information is not limited to the case where the scenario information is selected based on the meta information. The scenario information may be selected based on the terminal condition (whether or not the TV broadcast is being reproduced, the music is being reproduced, the silent mode is turned ON/OFF, or the like) when the event takes place. Also, the meta information is limited to that extracted from the contents. The meta information may be selected based on the data that are corresponded to the contents (a picture recording start time contained in the picture recording setting information, a picture recording end time, a recording time, a recording channel, and the like). Also, the meta information may be selected based on the data contained the program guide information (EPG, and the like) used in the picture recording or acquired newly after the picture recording is started (program title, performer's name, program start time, end time, genre, detailed information, etc.). Also, in the above embodiment, explanation is made by taking the case where the phone call is chosen as the sensed object of the event sensing unit by way of example. But this invention is not limited to this. A means for sensing electric mail arrival, TV phone arrival, instant message arrival, schedule alarm, warning of a remaining battery life, inside/outside cellphone service of the information terminal, or the like as the event may be employed. In addition, as the search conditions applied to select the scenario information by the controlling procedure holding unit, season, past arrival number of times, cumulative speaking time, remaining battery life, acceleration applied to an information terminal casing, position information, atmospheric temperature, open/close state of a folding information terminal, longitudinal/lateral switch state of an LCD display, ON/OFF state of a silent mode, noise level of the periphery, application being reproduced, sound peak level/average power of the reproduced contents, presence/absence of the human voice, and the like may be set, in addition to the phone number of the sender of the phone, the group to which the sender belongs, and the call incoming time. Also, as examples of variations of the informing contents, there may be considered the contents in which the event occurrence (phone call) is informed by the on-screen titles while sounding an informing sound of the news bulletin, the contents in which the knock sound and the moving picture to open the door are reproduced to fade in the phone screen and the phone melody, the contents in which the moving picture to slide the baseball player and the sound are reproduced to fade in the ringtone, the contents in which the information is repeated by a scratch sound that imitates a groove skipping of a record and a delay of sound, the contents in which a still picture, a speech, a moving picture (animation) are combined arbitrarily, and others. The present invention is explained in detail with reference to particular embodiments, but it is apparent for those skilled in the art that various variations and modifications can be applied without departing a spirit and a scope of the present invention. This application is based upon Japanese Patent Application (Patent Application No. 2004-247930) filed on Aug. 27, 2004; the contents of which are incorporated herein by reference. INDUSTRIAL APPLICABILITY The information terminal and the method of informing the event of the present invention have such an advantage that, since the reproduction of contents and the information of an occurrence of an event are carried out in previously set reproducing procedures, it is possible to inform the user of an occurrence of an event during the reproduction of contents without an unexpected feeling. As a result, the present invention is useful for controlling the contents reproducing operation, or the like when the event such as the phone call, or the like occurs while the contents are being reproduced.

<SOH> BACKGROUND ART <EOH>In recent years, on account of a size reduction and a capacity increase of the memory and an improvement in the sound compressing technology, the mobile terminal such as the cellular phone, or the like is also able to reproduce conveniently various contents such as the music, the moving picture, the television broadcast, and the like. In this situation it becomes an important control element to switch an output of an informing sound, or the like and a reproduced output of the contents and adjust the balance between them when the event occurs. For example, the information terminal device, the cellular phone, and the like, which can control adequately these outputs at a time of receiving a call or speaking on the phone, have been proposed (see Patent Literature 1, for example). Patent Literature 1: JP-A-2003-258988 (Pages 4 to 7, FIG. 1)

<SOH> BRIEF DESCRIPTION OF THE DRAWINGS <EOH>[ FIG. 1 ] A view showing a schematic internal configuration of an information terminal in an embodiment of the present invention. [ FIG. 2 ] A flowchart showing the controlling operation procedure performed when an event is sensed during the reproduction of contents, in the information terminal in the embodiment of the present invention. [ FIG. 3 ] A view showing a detailed internal configuration of the information terminal in the embodiment of the present invention. [ FIG. 4 ] A sequence diagram showing the contents reproduction controlling operation procedure performed when a phone call is sensed during the reproduction of contents, in the information terminal in the embodiment of the present invention. [ FIG. 5 ] A sequence diagram showing the contents reproduction controlling operation procedure performed when the phone call is sensed during the reproduction of contents, in the information terminal in the embodiment of the present invention. [ FIG. 6 ] A sequence diagram showing the contents reproduction controlling operation procedure performed when the phone call is sensed during the reproduction of contents, in the information terminal in the embodiment of the present invention. [ FIG. 7 ] A sequence diagram showing the contents reproduction controlling operation procedure performed when the phone call is sensed during the reproduction of contents, in the information terminal in the embodiment of the present invention. [ FIG. 8 ] A sequence diagram showing the contents reproduction controlling operation procedure performed when the phone call is sensed during the reproduction of contents, in the information terminal in the embodiment of the present invention. [ FIG. 9 ] A sequence diagram showing the contents reproduction controlling operation procedure performed when the phone call is sensed during the reproduction of contents, in the information terminal in the embodiment of the present invention. [ FIG. 10 ] A sequence diagram showing the contents reproduction controlling operation procedure performed when the phone call is sensed during the reproduction of contents, in the information terminal in the embodiment of the present invention. [ FIG. 11 ] A view showing an example of a description format of the character data inserted into contents data. [ FIG. 12 ] A view showing an example of a description format of the meta information. [ FIG. 13 ] A view showing a reference example of a control procedure table. [ FIG. 14 ] A timing chart showing contents of the contents reproduction controlling operation executed based on scenario information separately in terms of the video output and the sound output. [ FIG. 15 ] A timing chart showing contents of the contents reproduction controlling operation executed based on scenario information every control track. [ FIG. 16 ] A timing chart showing contents of the contents reproduction controlling operation executed based on scenario information every control track. [ FIG. 17 ] A view showing schematically respective changes of an image displayed on LCD and a sound level output to a head set on a timing chart until the on-hook is sensed after the phone call is sensed. [ FIG. 18 ] A timing chart showing contents of the contents reproduction controlling operation executed based on scenario information separately in terms of the video output and the sound output (informing contents are not reproduced). detailed-description description="Detailed Description" end="lead"?

20060918

20110503

20070816

92360.0

H04Q738

WANG-HURST, KATHY W

INFORMATION TERMINAL, AND EVENT NOTIFYING METHOD

UNDISCOUNTED

ACCEPTED

H04Q

ACCEPTED

SCREENING GRID

A screening grid for discharging solids from a liquid flow. The grid includes a driveable screening strip that can be inserted into the liquid flow and includes two lateral link chains between which carrying rods extend, carrying groups of adjacent screening links. All screening links include projecting parts that extend respectively only in one direction from a group of screening grids, without being overlapped by the projecting parts of the adjacent group of screening links. All of the screening links of a group are provided with projecting hooks on the outer side of the screening strip.

1-12. (canceled) 13. Screening grid for discharging solids from a liquid flow, the grid comprising a driveable screening strip that can be inserted into the liquid flow and comprising two lateral link chains between which carrying rods extend, the grid having screening links that at least partially have hooks whereby all screening links are divided into groups of adjacent screening links and with each group of screening links being arranged on two carrying rods independent of the preceding and subsequent group of screening links and with the screening links having projecting parts that extend past the carrying rods wherein all screening links have projecting parts that extend only in one direction from a group of screening links and without overlapping with projecting parts of the adjacent group of screening links. 14. Screening grid according to claim 13, wherein all screening links of a group are provided with projecting hooks on the outer side of the screening strip. 15. Screening grid according to claim 14, wherein the hooks are arranged on the projecting parts. 16. Screening grid according to claim 14, wherein the hooks are arranged on the center sections of the screening links that bridge the two carrying rods. 17. Screening grid according to claim 13, wherein at least one groups of screening links without hooks are arranged between groups of screening links with hooks. 18. Screening grid according to claim 13, wherein each projecting part is a sector that widens towards the inside of the screening strip whose arc center is arranged on the axis of the respective carrying rod. 19. Screening grid according to claim 13, wherein the screening links of adjacent groups are aligned. 20. Screening grid according to claim 13, wherein the screening links of adjacent groups are offset in relation to one another by half of the pitch of the screening links. 21. Screening grid according to claim 13, wherein the screening links are arranged directly adjacent to one another on the carrying rods and have lateral spacer sleeves. 22. Screening grid according to claim 13, wherein the adjacent screening links are separated by spacer sleeves. 23. Screening grid according to claim 13, wherein the carrying rods can be removed and replaced without interrupting the link chains. 24. Screening grid according to claim 13, wherein screening links with and without discharge hooks are alternately arranged on a carrying rod.

The invention concerns a screening grid for discharging solids from a liquid flow, said grid comprising a driveable screening strip that can be inserted into the liquid flow and comprising two lateral link chains between which carrying rods extend, carrying groups of adjacent screening links at least some of which have a hook, with each group of screening links being arranged on two carrying rods independent of the preceding and subsequent group of screening links and with the screening links having projecting parts that extend past the carrying rods. Such screening grids are used to mechanically remove solids that exceed a given particle size from liquids. A typical area of application is the cleaning of wastewater prior to the treatment in sewage treatment plants. For this purpose different designs of screening or filtering grids are known. The majority of such screening grids, like a continuous lift, have continuous rotating, driveable screening strips that are comprised of individual screening links whose spaces form the screening area through which the liquid stream, such as waste water, streams. At least some screening links have hooks that are used to pick up the solids when the screening strip is in motion and that discharge the solids from the liquid flow. At the head of the screening strip the solids are thrown onto a conveyor device. To remove materials that are stuck, it is possible to use a driveable brush, for example. In a known screening grid as described in the introduction (EP 0 581 770 B1) the projecting parts of the screening links of adjacent groups engage in a comb-like manner and form the screening areas between adjacent groups of screening links. During the reversing movement at the upper and lower end of the screening strip the projecting parts of the two adjacent groups of screening links must carry out a swiveling motion relative to one another. The resulting scissor effect between adjacent projecting parts can cause solids, especially hard materials or materials with long fibers, to get stuck between the projecting parts that move like scissors, which could impede the function of the screening grid. Since the gap width of the screening grid is determined by the distance of the projecting parts that engage in a comb-like manner in the area of two groups of screening links, additional intermediate screening links must be arranged between adjacent screening links of the same group in the area between the two carrying rods with said additional intermediate screening links not having any projecting parts. The necessity to provide two different types of screening links significantly increases the cost for the manufacture and repair of said screening grid. The object of the invention therefore is to provide a screening grid as described in the introduction so that it only has one type of screening link and that obstructions due to solids that get stuck due to the scissor-like movement of the projecting parts are avoided. This object is attained in accordance with the invention in that all screening links have projecting parts that only protrude in one direction from a group of screening links and are arranged without overlapping with projecting parts of the adjacent group of screening links. Since overlapping or comb-like engagement of projecting parts is avoided, there is no scissor-like movement that could cause the solids to get stuck. The gap width of the screening grid within each group of screening links as well as in the area between adjacent groups is solely determined by the mutual distance of the screening links that all are uniform. Additional intermediate screening links without projecting parts are not required. This considerably reduces manufacturing and repair costs. If necessary, the groups that are packets of screening links can easily be completely replaced. The screening grid can be such that all screening links of a group are provided with projecting hooks on the outer side of the screening strip. It is also possible to arrange one or several groups of screening links without hooks between groups of screening links with hooks. In any case, the lateral distance of the hooks is identical to the lateral distance of the screening links in relation to one another. Thus the gap width between the hooks equals the gap width of the screening strip. This ensures that all solids that the screening grid catches are also carried along for the discharge motion and are not dropped to the floor where solids would collect and would have to be regularly removed. It is practical for each projecting part to be a sector that increases in width towards the inside of the screening strip and whose center of the arc is arranged on the axis of the respective carrying rod. This ensures that there is not even an opening in the area of the reversal of the screening strip between adjacent groups of screening links but instead, the regular gap width of the screen is maintained. Other advantageous embodiments of the inventive thought are the subject of additional sub-claims. The invention is explained in more detail based on an exemplary embodiment that is shown in the drawing. The following is shown: FIG. 1 shows a vertical section of a simplified view of a screening grid that is arranged in a wastewater stream. FIG. 2 shows an enlarged partial view in the direction of arrow II in FIG. 1, FIG. 3 shows a view in the direction of arrow III in FIG. 2, FIG. 4 shows a side view of an individual screening link, FIG. 5 shows a view of the screening link according to FIG. 4 in the direction of arrow V, and FIG. 6-8 show side views of different embodiments of screening links according to FIG. 4 The screening grid shown in FIG. 1 is used to discharge solids, especially large solids, from a liquid flow, for example a waste water stream, in a waste water channel 1 in the direction of arrow 2. The lower section of the screening grid 3 extends into the wastewater stream and from there extends laterally to the top past the wastewater channel 1. The screening grid has a screening strip 5 that is continuously or intermittently driveable in the direction of arrow 4 with said strip running over a lower deflection pulley 6 and an upper deflection pulley 7 that is driven by a drive (not shown). Gravity causes the solids to be discharged. This can be supported by a—possibly driven—brush drum 8 and, if necessary, by a flushing mechanism (not shown). As shown in detail in FIGS. 2 and 3, the screening strip 5 has two lateral link chains 9 that run over deflecting pulleys 6 and 7. Carrying rods 10 extend at regular intervals between the two link chains 9 with flat side plates 11 being arranged on said carrying rods directly next to the link chains 9 and with the plates together forming a lateral delimitation on both longitudinal sides of the screening strip 5. The carrying rods 10 are fastened to the link chain 9 by means of fastening elements 12 (screws, bolts, etc.) and can be loosened. The fastening elements 12 can be secured with retaining elements 13. Two carrying rods 10 together carry a group 14 of screening grids 15 (FIGS. 4 and 5). Each screening link 15 has two bearing orifices 16, 17 that are arranged on the carrying rods 10 and are connected to each other via the center section 18. FIG. 2 shows that the bearing orifices 16 extend enough on both sides so that a screening gap 19 is formed between the center sections 18 of adjacent screening links 15 with the gap of the said screening gap determining the minimum size of the solids that are screened out. All screening links 15 have projecting parts 20 that only extend in one direction of a group 14 of screening links 15 and project past the carrying rod 10. The gap 21 that is formed by two adjacent projecting parts 20 is as wide as the gap 19 between the center sections 18 of adjacent screening links 15. When mounted, the projecting parts 20 extend up to a short distance to the bearing orifices 16 of the adjacent group 14 of screening links 15. All projecting parts 20 extend only in one direction of a group 14 of screening links 15 and do not overlap with the projecting parts 20 of the respective adjacent group 14. In the exemplary embodiment shown in FIG. 1-5, all screening links 15 of a group 14 have a projecting hook 22 on the outer side of the screening strip 5. Each hook 22 is arranged on the projecting part 20. During the continuous or intermittent driven movement of the screening strip 5 the hooks 22 take up the solids that the screening strip catches and carry them to the head of the screening strip 5. Each projecting part 20 is a sector that widens towards the inside of the screening strip 5. The center of the arc 23 (FIG. 4) of the sector is located in the middle of the bearing orifice 17 and thus is mounted on the axis of the respective carrying rod 10. This ensures that during a swiveling movement of the screening links 15 when running over deflection pulleys 6 and 7, the gap between the screening links 15 of adjacent groups 14 does not widen and that there is no scissor movement that could cause solids to get stuck. In the arrangement shown in FIG. 3, the screening links 15 of adjacent groups are offset in relation to one another by half, i.e. by half the width of the screening links 15. It is also possible to arrange the screening links 15 of subsequent groups 14 so that the screening links 15 are aligned with one another. In the exemplary embodiment shown, the screening links 15 are arranged directly adjacent to one another on the carrying rod 12. The bearing orifices 16, 17 form spacer sleeves that project from the sides. It is also possible to have flat screening links 15 and to separate adjacent screening links 15 by way of separate spacer sleeves. The screening link 15 shown in FIG. 4 is arranged in the screening strip 5 in a manner that ensures that the projecting part 20 carrying the hook 22 follows in the direction of arrow 4 during the conveyor movement. The screening link 15 shown in FIG. 6 is different only in that the projecting part 20 runs ahead in the direction of arrow 4 during movement with the projecting part 20 that runs ahead carrying the hook 22. Contrary to that, the hook 22 in the embodiment of the screening link 15 according to FIG. 7 is arranged on the center section 18 that bridges the two carrying rods. FIG. 8 shows a screening link 24 without hook. The screening link 23 also has a projecting part 25. Such screening links 23 without hooks are also combined into groups adjacent to one another on two carrying rods 10. One or several groups of screening links 23 without hooks can be arranged between groups 14 of screening links 15 with hooks 22. The gap width of the screening strip 5 remains the same for all screening links shown in all material carrying (discharge material) movement locations of the screening strip. When the screening strip is reversed around deflecting pulleys 6 and 7, there are no larger openings in which solids could get stuck. The filter elements can be adjusted based on their shape so that there is no large opening anywhere on the screening strip during reversing. Since all carrying rods 12 have the same length, the individual groups 14 of screening links 14 [sic] can easily be replaced in groups for repair purposes. Deviating from the exemplary embodiments that are shown, it is possible to alternate adjacent screening links with or without discharge hooks on one carrying rod 12.

20060918

20130806

20110616

66563.0

B01D3304

POPOVICS, ROBERT J

SCREENING GRID

SMALL

ACCEPTED

B01D

ACCEPTED

Self-Storing Medical Electrodes

The present invention provides a self-storing medical electrode (10) that does not require packaging, enclosures, or other means to house and to protect various electrode components. According to one aspect, the invention provides an electrode comprising an electrode body having first and second sides, wherein the first side comprises a barrier layer (15) comprising a heat-sealable material and the second side comprises a conductive layer (16). The electrode further comprises an electrically conductive gel layer (18) disposed on the electrode body and which is further in electrical communication with the conductive layer (16).

1. An electrode comprising: an electrode body having a first and second side, wherein the first side comprises a flexible barrier layer comprising a heat-sealable material and the second side comprises a conductive layer; an electrically conductive gel layer disposed on the electrode body and which is further in electrical communication with the conductive layer; and a release liner sealed to said flexible barrier layer around a periphery of said gel layer. 2. The electrode of claim 1, wherein the heat-sealable material comprises a thermoplastic polymeric material. 3. The electrode of claim 1, wherein the flexible barrier layer further comprises a vapor or air barrier material comprising a polymeric film or sheet, a foil material, or a coated substrate comprising a metal, textile, paper, or non-woven material coated with a polymeric material. 4. The electrode of claim 1, wherein the flexible barrier layer further comprises a vapor or air barrier material comprising a fluoropolymer film. 5. The electrode of claim 1, wherein the flexible barrier layer comprises a laminate comprising a first layer of a heat-sealable layer comprising polyethylene disposed over a second layer of a vapor barrier comprising a fluoropolymer film. 6. The electrode of claim 1, wherein the conductive layer comprises a metal sheet or foil, a conductive ink, or a laminate comprising a metal component disposed over a polymeric substrate. 7. The electrode of claim 1, wherein the electrode further comprises a lead wire that is connected to the flexible barrier layer of the electrode and which electrically connects the electrode to a medical device. 8. The electrode of claim 1, wherein said release liner is substantially rigid. 9. An electrode system comprising: a pair of electrodes disposed on opposite sides of a non-conductive release liner, wherein each electrode comprises an electrode body having first and second sides, wherein the first side comprises a flexible moisture barrier layer having a sealable periphery and the second side comprises a conductive layer, and an electrically conductive gel layer interposed between the conductive layer and the non-conductive release liner, wherein the periphery of the moisture barrier layer of each electrode is sealed to the release liner. 10. The electrode system of claim 9, wherein the electrodes are further in electrical contact with each other through a conductive element that is disposed within the non-conductive release liner and which is in electrical contact with both electrodes through said gel layer. 11. The electrode system of claim 9, wherein each electrode further comprises a lead wire that is connected through said first side to said second side of the electrode and which electrically connects the electrode to a medical device. 12. The electrode system of claim 11, wherein the lead wire is electrically connected to the conductive layer and the electrically conductive gel by a connector comprising a rivet, ring tung terminal, staple, grommet, screw, bolt, or other electrically conducting fastening means that extends from the flexible non-conductive release liner through the conductive layer. 13. The electrode system of claim 12, wherein the electrode further comprises an insulation layer interposed between a portion of the conductive layer and the non-conductive release liner, wherein the insulation layer protects an operator of the electrode from physical contact with the connector which is electrically connected to an electrical source. 14. The electrode system of claim 9, wherein the non-conductive release line r comprises a polymeric sheet, coated paperboard, or foam. 15. The electrode system of claim 9, wherein the non-conductive release liner comprises a material treated with an adhesion-reducing agent comprising a surface-treated polymeric sheet comprising siliconized polyethylene, polypropylene, polyester, acrylate, polycarbonate, or wax or plastic coated paperboard or foam. 16. The electrode system of claim 9, wherein the conductive layer comprises a laminate comprising tin foil and polyester. 17. The electrode system of claim 9, wherein the release liner further comprises a rigid release liner. 18. A self-storing electrode system comprising: first and second electrode bodies each having a first and second side, wherein the first side comprises a flexible moisture barrier layer having a sealable periphery and the second side comprises a conductive layer which does not extend to the periphery of the moisture barrier layer; an electrically conductive gel disposed on each of the electrode bodies which is in electrical communication with the conductive layer of each electrode; a release liner sealed by a seal to the periphery of the flexible moisture barrier layer to protect and prevent desiccation of the gel layer; and a lead wire electrically coupled to each electrode by means of a path that does not disrupt the moisture integrity of the release liner seal. 19. The self-storing electrode system of claim 18, wherein the release liner seal further comprises a heat-seal formed between the flexible barrier layer and the release liner. 20. The self-storing electrode system of claim 18, wherein the flexible moisture barrier layer further comprises a vapor or air barrier material comprising a polymeric film or sheet, a foil material, or a coated substrate comprising a metal, textile, paper, or non-woven material coated with a polymeric material. 21. The self-storing electrode system of claim 18, wherein the flexible moisture barrier layer comprises a laminate comprising a first layer of a heat-sealable material comprising polyethylene disposed over a second layer of a vapor barrier comprising a fluoropolymer film. 22. The self-storing electrode system of claim 18, wherein the release liner is substantially rigid. 23. The self-storing electrode system of claim 18, wherein the lead wire is connected to the conductive layer of the electrode for electrically connecting the electrode to a medical device.

The present invention relates in general to electrodes for medical instruments, and more particularly, to self-storing medical electrodes in a defibrillator/pacing device and methods of making and using same. Sudden cardiac death is the leading cause of death in the United States. Most sudden cardiac death is caused by ventricular fibrillation (“VF”), in which the muscle fibers of the heart contract without coordination, thereby interrupting normal blood flow to the body. The only known treatment for VF is electrical defibrillation, in which an electrical pulse is applied to a patient's heart. The electrical shock clears the heart of the abnormal electrical activity (in a process called “defibrillation”) by depolarizing a critical mass of myocardial cells to allow spontaneous organized myocardial depolarization to resume. One way of providing electrical defibrillation is by automatic or semi-automatic external defibrillators, collectively referred to as “AEDs,” which send electrical pulses to a patient's heart through electrodes applied to the torso to defibrillate the patient or to provide for external pacing of the patient's heart. The use of AEDs by untrained or minimally trained operators for a patient in sudden cardiac arrest is a time critical operation. The electrical pulse must be delivered within a short time after onset of VF in order for the patient to have any reasonable chance of survival. Thus, simplifying and minimizing the number of steps required by the operator to defibrillate and improving the reliability of defibrillation increases key aspects of an AED design. The AED is typically stored with electrodes that are sealed in an enclosure that protects the electrodes from contamination and retards desiccation. Before defibrillation can commence the operator must open the enclosure, remove the electrodes, and apply them to the patient. Electrodes that are sealed with a connector inside an enclosure, such as a bag, can require multiple steps by the operator. First, the operator must open the sealed bag. Second, the operator must plug the electrodes into the AED. Third, the operator must remove a release liner, which typically covers a gel on the electrode pads from the first electrode and fourth, the operator must place the electrode on the patient. The operator must then repeat the fourth step with the second electrode and place the second electrode on the patient. The electrodes typically comprise a non-conductive base layer such as a plastic disc and a conductive layer that distributes the current transmitted to the electrode by the defibrillator. The base layer is typically constructed of a thin, flexible polymeric material such as urethane foam, or a polyester or polyolefin laminate which is electrically insulating and provides structural integrity to the electrode. Conventionally, such electrodes further include a layer of adhesive material that is used to adhere the electrode to the patient's chest prior to and during delivery of the shocks. The adhesive material is typically a viscous water-based gel material that contains ionic compounds which increase the material's electrical conductivity to provide a low resistance path for current to flow from the electrode to the patient's chest. As is known in the art, electrodes used with automatic external defibrillators often are stored for relatively long periods of time until needed. During this time, the adhesive material can become desiccated. This desiccation decreases the effectiveness of the material in that it lowers the material's conductivity, which in turn raises the impedance at the contact area between the electrode and the skin. This increased impedance results in less current reaching the heart. Due to the problem of desiccation, the adhesive material normally is covered with a removable backing that reduces the material's exposure to air. Despite the provision of such backings, however, conventional adhesive materials still tend to dry out. For the purpose of preventing such desiccation, modern medical electrode packaging typically provides a sealed electrode storage environment and through-wall electrical connectivity to electrotherapy devices such as external defibrillators. The electrode packaging is typically either a flexible, heat-sealable laminate material, or a rigid, molded plastic material, both of which serve as a moisture barrier. Flexible electrode housings such as foil-lined plastic bags provide economical and simple packaging for electrodes in many instances. Electrode wires may extend through the exteriors of known flexible housings, and connect directly to electrotherapy devices. A seal around the wires is typically achieved by heat-sealing the packaging material to the wires or by molding a plastic piece around the wires and sealing the packaging material to the piece. The electrodes themselves are typically arranged in the package so that they form an electrical circuit between themselves and the associated medical device. Prior art flexible housings, however, suffer from several drawbacks. Electrode function or sterility, for instance, may be compromised when electrode wiresets protrude through the flexible housing. For example, flexing may weaken the bond between the electrode wireset and the flexible material. In addition, the flexible material of the packaging may remain adhered to the electrode wires after placement of the electrodes on a patient, causing user confusion or delay. Further, adequately sealing areas where the electrode wires extend through flexible housings continues to present challenges and may increase manufacturing costs or complexity. Rigid structures offer an alternative to flexible housings. Walls of rigid structures may include insert-molded electrical contacts, such as pins, which provide through-wall electrical connectivity between enclosed electrode wires and external electrotherapy devices. Thus, the electrode wires do not exit the cartridge, but rather, are permanently attached to electrical contacts that pass through the wall of the rigid structure. These electrical contacts complete the electrical connection to the intended device. Although rigid housing structures may sometimes be more expensive and have higher manufacturing costs than flexible housings, rigid structures are often selected because they have been designed to enclose electrode wiresets without compromising the seals of the structure, and they offer relatively simple user interfaces. Rigid structures, however, may be less desirable in some applications, such as at high altitudes, when pressures inside the structures greatly exceed ambient pressures. Also, heat-seal film, which is often stretched over rigid structure openings, may be vulnerable to puncture. In addition to these disadvantages, these prior art electrode packaging materials, whether rigid or flexible, are external to the electrode and must be disengaged from the electrodes prior to deployment of the electrodes. For instance, prior art packaging comprising a flexible, heat-sealable pouch or envelope-style structure must be torn and removed and any sort of release liner or backing material adhered to the conductive gel must be stripped away in two separate steps. These are steps which reduce the efficiency of the device operator during a life-saving process such as cardiac defibrillation. There is a long-standing need for an electrode storage system that is integrated within and is part of the electrode itself and that prevents desiccation of the electrically conductive gel materials contained therein. Such a self-storing electrode would allow for long-term sealed storage of the electrodes and ease of operation of the electrodes without the limitations of prior art flexible and rigid housings, particularly flexible housings that must be torn off prior to use. In addition, such self-storing electrode would be useful in a wide array of applications for both receiving and transmitting current such as, for example, in cardiac defibrillation. The present invention meets the aforementioned needs by providing a self-storing medical electrode that does not require packaging, enclosures, or other means to house and to protect the electrode during long-term storage. According to one embodiment, the invention provides an electrode comprising an electrode body having first and second sides, wherein the first side comprises a flexible barrier layer comprising a heat-sealable material and the second side comprises a conductive layer. The electrode further comprises an electrically conductive gel layer disposed on the electrode body and which is further in electrical communication with the conductive layer. According to another embodiment, the invention provides an electrode system comprising a pair of electrodes disposed on opposite sides of a non-conductive release liner, wherein the electrodes are in electrical contact with each other through a conductive element that is disposed within the non-conductive release liner and which is in electrical contact with both electrodes. An electrically conductive gel layer is interposed between the conductive layer and the non-conductive release liner, and the gel layer is in electrical contact with the conductive element disposed within the non-conductive release liner. In yet another embodiment, the invention provides a method of manufacturing a self-storing electrode system comprising providing two electrode bodies each having a first and second side, wherein the first side comprises a flexible barrier layer comprising a heat-sealable material and the second side comprises a conductive layer. According to one embodiment of this invention, the electrode body is placed on opposite sides of a non-conductive release liner, and each side has a recessed portion containing an electrically conductive gel, and the non-conductive release liner contains a conductive element which is electrically connected with the electrically conductive gel on either side of the non-conductive release liner. A lead wire is affixed to each electrode by a connecting means that electrically connects the lead wire to the conductive layer of each electrode. Preferably heat or other sealing means as discussed below is applied to the flexible barrier layers to form a heat seal or other moisture-proof seal between the flexible barrier layer and the non-conductive release liner. In the drawings: FIG. 1 provides a top view of a electrode assembly usable in connection with embodiments of the present invention that is disposed on a non-conductive release liner, with a portion of the electrode peeled back to reveal the various layers of the electrode. Detail A provides a detailed cross-sectional side view of the detailed portion A of the electrode. FIG. 2 provides an exploded perspective view of an electrode system in accordance with another embodiment of the present invention comprising a pair of electrodes disposed on opposite sides of a backing and illustrating connections for connecting the system to an external medical device. FIG. 3 provides a cross-sectional view of the electrode assembly of FIG. 1 along line B. FIG. 4 provides a top semi-transparent view of a partially assembled electrode assembly in accordance with an embodiment of the present invention. Turning now to the drawings, wherein like numerals designate like components, FIG. 1 illustrates a top view of a medical electrode assembly 10 usable in connection with aspects of the present invention comprising an electrode 12 that is disposed on a non-conductive release liner 22, with a portion of the electrode 12 peeled back via a peel tab 34 to reveal the various layers of the electrode assembly 10. The elements of a medical electrode 12 according to this embodiment of the present invention comprise an electrode body having a first and a second side, wherein the first side comprises a flexible barrier layer 14 comprising a heat-sealable material 15 and the second side comprises a conductive layer 16. The medical electrode 12 further comprises an electrically conductive gel layer 18 disposed on the electrode body 12 and which is in electrical communication with the conductive layer 16. The gel layer 18 is adjacent to non-conductive release liner 22. As shown in Detail A of FIG. 1, the flexible barrier layer 14 comprising the heat sealable layer 15 overlies and is coupled to the conductive layer 16, which in turn is disposed over the gel layer 18. The gel layer 18 is placed adjacent to the non-conductive release liner 22. In some embodiments, the electrode further comprises a lead wire 24 that electrically connects the electrode to a medical device (not shown) such as an AED. As shown in Detail A, in one embodiment the electrode comprises a lead wire 24 that is connected to the flexible barrier layer 14 of the electrode 12 and which electrically connects the electrode 12 to a medical device. As would be appreciated by one of skill in the art, the lead wire 24 can be electrically connected to the electrode 12 by a connector 28 or connecting means, including but not limited to, a rivet, ring tung terminal, staple, grommet, screw, bolt, or a pin connector or other electrically conducting fastening means which is capable of causing electrical signals, or representations thereof, to traverse the flexible barrier layer 14 to the conductive layer 16. Thus, connector 28 can be disposed such that the lead wire 24 passes around, and not through, the heat seal seam formed by flexible barrier layer 14 and non-conductive release liner 22. In certain embodiments the connector 28 is applied using standard grommet or rivet means and materials. For example, as shown in Detail A of FIG. 1, a rivet 42 which traverses the flexible barrier layer 14 and the conductive layer 16 of the electrode 12 is held in place by a washer 44. This connector 28 presses against the flexible barrier layer 14, resulting in a tight, form-fitting seal between the connector 28 components and the flexible barrier layer 14, similar to plumber's tape (polytetrafluoroethylene) that is used to seal pipe fittings together. As will be appreciated by one of skill in the art, the conductive layer 16 may comprise any of a number of prior art means for transferring current or voltage to the gel layer 18. Specific examples include thin layer strips of a conductive material such as a metal sheet or foil, or a laminate composition comprising a metal such as tin foil and a polymeric or other substrate material to provide physical support such as polyester. In some other embodiments, the conductive layer 16 comprises a conductive ink that is printable on a substrate surface. For example, the conductive layer 16 may comprise a silver and carbon/graphite-based ink and any number of resins that are applied to the surface of a printable surface such as polyvinylchloride, polypropylene or another polymer substrate. In yet another embodiment, and as illustrated by an exploded perspective view in FIG. 2, the present invention provides an electrode system 10 comprising a pair of electrodes 12 disposed on opposite sides of a non-conductive release liner 22, wherein the electrodes 12 are in electrical contact with each other through a conductive element 36 that is disposed within the non-conductive release liner 22 and which is in electrical contact with both electrodes 12 via the electrically conductive gel layer 18. The use of a common non-conductive release liner 22 for both electrodes provides a convenient means of maintaining electrical contact between them, whether by the conductive element 36 as shown in FIG. 2 or any other means known in the prior art, including a single conductive strip extending from the conductive layer 16 of one electrode 12 to another, or separate conductive strips extending from the conductive layer and meeting at the periphery of the non-conductive release liner 22, such that electrical communication between the electrodes 12 is maintained. Electrodes for transmitting electrical energy such as those used in a pacer/defibrillator obtain energy from an electrical source 40. An electrical circuit is completed through the circular loop at the proximal ends of the lead wires 24 which are in electrical communication with a connector 28 such as a conductive rivet 42 which impregnates, traverses, penetrates, or otherwise extends through both the flexible barrier layer 14 and the conductive layer 16. The distal end of the lead wire 24 connects with a cable 48 that connects with a connector plug 50 or other means for plugging to an external medical device such as an AED. Since it is desirable that any electrical charge carried from a defibrillator or other medical device to the patient through the lead wire occurs in a controlled manner during defibrillation and not while the operator is carrying out preparatory steps prior to deployment, in some embodiments an insulating layer 38 is provided. Removal of the electrode 12 from the backing 24 exposes the rivet 42. In order to protect the operator from physical contact with the connector 28 which is electrically connected to an electrical source 40, the electrode further comprises an insulation layer 38 interposed between a portion of the conductive layer 16 and the non-conductive release liner 22 such as the heel-shaped insulating layer 38 shown in FIG. 2. In the embodiment shown in FIG. 2, the non-conductive release liner 22 has two sides, each side having a recessed portion 25. The recessed portion 25 is shaped to store the electrically conductive gel layer 18 of each electrode. In other embodiments, the non-conductive release liner 22 includes a second recessed portion 46 that accommodates the contours of the connector 28 such as the rivet 42 such that a generally flat and thin geometry of the electrode assembly is achieved. In some embodiments, the heat-sealable material 15 comprises a thermoplastic polymeric material. As used herein, a “heat sealable” or “heat seal coated” material refers to a substrate that readily forms a seal between itself and another surface of a like or different substrate with the application of heat. Some heat sealable or heat seal coated materials are also effective as vapor, moisture or air barriers. Typically, the heat-sealable material comprises a thermoplastic polymeric material. A variety of heat sealable and heat seal coated materials are commercially available, and are within the scope of the present invention. For example, in some embodiments the heat sealable material comprises films of polyethylene, spun-bonded polyolefin (TYVEK®, DuPont, Wilmington, Del.), polyvinyl chloride, ionomer resin, polyamides, polyester, polypropylene, polycarbonate, or polystyrene. A heat-sealable flexible laminate material suitable for use with the present invention is commercially available from Cadillac Products, Inc. in Troy, Mich. As would be appreciated by one of skill in the art, the heat-sealable flexible material could alternatively be comprised of two layers, including a moisture barrier layer 17 under a separate heat-sealing layer 15. The layers may also be arranged in a different order. Thus, in one embodiment, the flexible barrier layer 14 further comprises a vapor or oxygen/air barrier material 17 comprising a polymeric film or sheet, a foil material, or a coated substrate comprising a metal, textile, paper, or non-woven material coated with a polymeric material. Some exemplary vapor or air barrier materials 17 preferably comprise a laminate such as a metallized polyester that has been laminated to low-density polyethylene (MPPE). In another embodiment, the vapor or air barrier comprises a fluoropolymer film such as polychlorotrifluoroethylene (e.g., ACLAR®, Honeywell). Referring now to FIG. 3, a cross-sectional view of the electrode assembly 10 of FIG. 1 along line B illustrates another embodiment. The flexible barrier layer 14 comprises a laminate comprising a first layer of a heat-sealable outer layer 15 disposed over a second layer of a vapor or air barrier 17. For example, the flexible barrier layer 14 comprises a polyolefin heat sealable layer 15 such as polyethylene disposed over a second layer of a vapor barrier 17 comprising a fluoropolymer film such as polychlorotrifluoroethylene, commercially available as ACLAM®, from Honeywell or a polymer laminate such as MPPE. A conductive element 36 traverses the thickness of the non-conductive release liner 22, such that it is in electrical communication with the conductive layer 16 of the electrodes on either side of the non-conductive release liner 22 (and therefore, the electrodes are in electrical communication with each other). The gel layer 18 may comprise any number of widely-available conductive compounds that maintain direct electrical contact with the skin and permits continued contoured adhesion to the body of a patient. The gel layer 18 may preferably also possess a pressure sensitive quality to promote adhesion to the body of a patient. As will be appreciated by one skilled in the art, a wide variety of substrates may be utilized as a non-conductive release liner 22 in the practice of the present invention. Typically, such non-conductive release liner 22 material is chosen such that the electrically conductive gel layer 18 of the electrode 12 will readily peel away from the non-conductive release liner 22 while remaining attached to the electrode body 12. In some preferred embodiments, the non-conductive release liner 22 comprises a polymeric sheet such as high-density polyethylene, a coated paperboard, or foam, such that the backing provides a relatively rigid surface with respect to the flexible electrode 12 which is peeled away from the backing just prior to use. To facilitate ease of removal of the heat sealed electrode 12 from each side of the backing material 22, in some embodiments the non-conductive release liner 22 comprises a material treated with an adhesion-reducing agent such as a surface-treated polymeric sheet. For example, the non-conductive release liner 22 may comprise siliconized polyethylene, polypropylene, polyester, acrylate, polycarbonate, or wax or plastic coated paperboard or foam. An adhesion-reducing agent as used herein refers to an agent that, when applied to a substrate, reduces the coefficient of friction of that substrate. In other embodiments, depending on the choice of heat-sealable material 14 that is chosen, the release liner 22 may comprise an uncoated or non-surface treated substrate from which the heat-sealable material 14 will readily peel off. In other embodiments, at least a portion of the recessed portion 25 of the release liner 22 that comes into contact with the electrically conductive gel layer of the electrode is coated with an adhesion-reducing material such that the gel separates cleanly from the backing. Other portions of the release liner 22 that are sealed directly to the heat-sealable layer 15 are left uncoated since it is desired that a strong heat seal be maintained between the release liner and the heat-sealable layer 15 during extended storage of the electrodes 12. The present invention also provides a method of manufacturing a self-storing electrode system comprising providing two electrode bodies 12 each having a first and second side, wherein the first side comprises the flexible barrier layer 14 comprising a heat-sealable material 15 and the second side comprises the conductive layer 16. According to one embodiment of this aspect, the electrode body 12 is placed on opposite sides of the non-conductive release liner 22, and each side has a recessed portion 25 containing the electrically conductive gel 18, and the non-conductive release liner 22 contains a conductive element 36 which is electrically connected with the electrically conductive gel 18 on either side of the non-conductive release liner. Preferably heat or other sealing means such as pressure is applied to the flexible barrier layer 14 to form a vapor, air and/or moisture-proof seal between the flexible barrier layer 14 and the non-conductive release liner 22. As discussed above, the flexible barrier layer 14 in some embodiments may comprise a vapor or air barrier material 17 comprising a polymeric film or sheet such as a fluoropolymer film, a foil material, or a coated substrate comprising a metal, textile, paper, or non-woven material coated with a polymeric material. The flexible barrier layer may also comprise a laminate comprising a first layer of a heat-sealable material such as polyethylene disposed over a second layer of a vapor barrier such as a fluoropolymer film. FIG. 4 is a semi-transparent top view of a partially fabricated electrode assembly 10 of the present invention, illustrating the relative geometry and placement of the heat-sealable layer 15, the conductive layer 16, and the electrically conductive gel 18 with respect to one another. It is desirable that the heat sealable layer 15 be disposed over the entire surface of the underlying electrically conductive gel layer 18 and the conductive layer 16 and even more desirably, extend over the periphery of the underlying layers such that a heat seal zone 48, for example, the area of the heat-sealable layer 15 between the dotted lines indicated in FIG. 4, may be formed near the periphery of the heat seal layer 15. In this embodiment a semi-circular insulating layer 38 covers a portion of the electrode containing an electrically conductive connector 28 such as a rivet 42. One edge 52 of the insulating layer 38 is partially disposed under the electrically conductive layer 18 such that the rivet 42 is electrically isolated from the electrically conductive layer 18 and remains covered during deployment of the electrode on the patient. A seal is created in the heat-sealing zone 48 around the perimeter of the heat-sealable layer 15 by applying heat or in other ways such as application of hot-melt adhesive or double-sided adhesive tape or ultrasonic welding, for example. The electrode assembly 10 of the present invention may be used with an electrotherapy system such as an automatic or manual external defibrillator system, or another type of electrotherapy system such as pacing or cardiac monitoring systems. A defibrillator system typically includes an energy source which provides voltage or current pulses. A controller operates an energy delivery system to selectively connect and disconnect energy source to and from one or more electrodes electrically attachable to a patient. A defibrillator system may further include elements such as user input and/or output devices or displays, memories, or computer-executable instructions implemented in software, firmware, hardware or a combination thereof. Communication between a medical device and the electrode assembly 10 may be established via a connector plug 50 when a portion of the medical device, such as a connection for energy delivery from an energy source is coupled to one or more lead wires 24 via a cable 48. Thus, when the electrodes 12 are assembled in accordance with aspects of the present invention and when the medical device is coupled to lead wires 24 via a cable 48, the electrodes 12 remains responsive to the medical device during shipping, storage or use. For example, communication may be established between an electrode assembly 10 and a medical device for purposes of testing the functionality of the electrode 12 while the medical device is in standby mode, and the medical device and/or electrodes 12 may be enabled to alarm if a problem is detected. In another example, communication between the electrodes 12 and the medical device may be used to monitor other parameters of interest, such as the interior environmental conditions of the electrodes 12. Additional connections such as signal conductors could be used to facilitate monitoring of such additional parameters. In a further example, there may be continual communication between the medical device and the electrodes 12 during normal operation of the medical device in connection with patient therapy. In the case of a defibrillator, for example, an electrode 12 may be placed on a patient and the defibrillator may continue to provide/receive electrical communication and information to/from electrode 12 via medical device during patient treatment and monitoring, without further user intervention. The electrode assembly 10 of the present invention provides flexible manufacturing/assembly and a streamlined procedure for readying the electrodes for deployment on a patient that reduces set-up time. Integrating heat-sealable flexible materials and vapor and air barrier materials directly into the electrode itself and sealing the electrode directly to a backing material provides superior electrode storability and longevity. Such self-storing electrodes 12 remain responsive to electrotherapy devices and may be monitored for functionality and used for patient therapy without interruption of the connection from the electrotherapy device.

20060920

20101026

20070830

66547.0

A61N100

BEHRINGER, LUTHER G

SELF-STORING MEDICAL ELECTRODES

UNDISCOUNTED

ACCEPTED

A61N

ACCEPTED

Process For Fabricating Electronic Components And Electronic Components Obtained By This Process

The invention relates to a method for producing electronic components consisting in carrying out a first anodisation of a carrier material (1) for forming at least one first pore (3) extending in a first direction in said carrier material (1) and in carrying out a second anodisation for forming at least one second pore (17) extending in the carrier material (1) in a second direction different from the first direction

1. A process for fabricating electronic components, in which a first anodizing operating is carried out on a support material in order to form at least one first pore that extends, in this support material, along a first direction, comprising a second anodizing operation carried out in order to form at least one second pore that extends in the support material along a second direction, different from the first direction. 2. The process as claimed in claim 1, wherein an insulating material is formed in the first pore. 3. The process as claimed in claim 1, wherein an active material is formed in the second pore. 4. The process as claimed in claim 3, wherein the active material is chosen from a conductor, a semiconductor, a superconductor, a magnetic material and a carbon structure. 5. The process as claimed in claim 3, wherein the active material is deposited in the second pore by electrodeposition 6. The process as claimed in claim 5, wherein the active material is a semiconductor material transparent to light. 7. The process as claimed in claim 6, wherein the semiconductor material is an organic material. 8. The process as claimed in claim 1, wherein the support material constitutes both a self-supporting structure for a components and electrical contact means. 9. The process as claimed in claim 1, wherein a transistor is produced, the source and drain contacts of which are each at one of the ends of the second pore, respectively, and a gate contact is produced by depositing a conducting material on the surface layer 10. The process as claimed in claim 1, wherein the support material is in the form of a position of a wire extending longitudinally parallel to the second direction 11. The process as claimed in the claim 10, wherein a plurality of pores, including the first pore, are formed, each extending substantially over the thickness of a surface layer of the wire, radically perpendicular to the second direction. 12. The process as claimed in claim 11, wherein the surface layer of the wire constitutes a layer of dielectric. 13. The process as claimed in claim 1, wherein at least one active element is enveloped in a matrix comprising the support material. 14. The process as claimed in claim 13, wherein an electrically conducting material is deposited in at least one of the first and second pores. 15. The process as claimed in claim 13, wherein a thermally conducting material is deposited in at least one of the first and second pores. 16. The process as claimed in claim 13, wherein an optically conducting material is deposited in at least one of the first second pores. 17. The process as claimed in claim 13, wherein at least one line of a material chosen from an electrically conducting material, a thermally conducting material and an optically conducting material is produced on the surface of the support material, in order to connect the active element to an external element. 18. The process as claimed in claim 1, wherein at least three treatment steps in liquid medium, including the first anodizing operation, the second anodizing operation and an electrodeposition step. 19. An electronic component obtained by the process as claimed in claim 1, further including an element of support material with at least one first pore that extends along a first direction and at least one second pore that extends along a second direction, different from the first direction. 20. The component as claimed in claim 19, wherein the second pore is at least partly filled with an active material. 21. The component as claimed in claim 20, wherein the active material is chosen from a conductor, a semiconductor, a superconductor, a magnetic material and a carbon structure. 22. The component as claimed in claim 20, wherein the active material is transparent to light. 23. The component as claimed in claim 20, wherein the active material is an organic material 24. The component as claimed in claim 20, wherein a first electrical contact is produced between the active material and the support material, on the bottom of the second pore 25. The component as claimed in claim 19, wherein the support material constitutes both a self-supporting structure for the component and electrical contact means 26. The component as claimed in claim 19, wherein the element of support material is in the form of a wire portion that extends longitudinally parallel to the second direction 27. The component as claimed in claim 26, wherein the wire portion includes, at the second pore, a surface layer consisting of an electrically insulating material 28. The component as claimed in claim 27, wherein a second electrical contact, radically external with respect to the surface layer, is produced on this surface layer. 29. The component as claimed in claim 19, further including at least one active element connected via the first and second pores to the surface of the support material.

The invention relates to processes for producing electronic components and to the electronic components obtained by this process. Patent application FR 03/11959 already discloses processes for fabricating electronic components, in which a first anodizing operation is carried out on a support material in order to form at least one first pore that extends, in this support material, along a first direction. In these processes, an anodizing operation is carried out on a material in order to form, in the latter, pores suitable for accommodating an active material. For example, in document FR 03/11959, the active material is a carbon nanotube, the growth of which was constrained and oriented by the geometry of the pore in which this growth took place. These processes are aimed at making it easier to integrate nanostructures into a standard microelectronic device (for example of the CMOS type). As an alternative, the inventors have sought to use this type of nanofabrication process with a view to higher-level integration. Thus, according to one method of implementing the invention, a process is provided for fabricating electronic components in which, apart from the abovementioned features, a second anodizing operation is carried out in order to form at least one second pore that extends in the support material along a second direction, different from the first direction. According to this method of implementing the invention, the pores may be used to grow and/or organize nanobricks. Furthermore, pores oriented essentially along at least two different directions are obtained. This makes it easier to carry out separate treatments according to the various orientations of the pores. It is thus possible to ascribe different functions to the pores along each of these directions. For example, the pore or pores extending along the first direction may be used to produce one function of the electronic component, for example the gate of a transistor, while the pore or pores extending along the second direction may be used to produce a second function of the component, for example the drain of a transistor. According to other methods of implementing the invention, one or more of the following provisions may optionally be employed: an insulating material is formed in the first pore, i.e. in a first anodized layer; an active material is formed in the second pore, i.e. a second anodized layer. This active material is for example chosen from a semiconductor, a superconductor, a magnetic material and a carbon structure; a semiconductor material is deposited in the second pore by electrodeposition. This semiconductor material is for example transparent to light. It may be an organic material, such as polypyrrole; the support material constitutes both a self-supporting structure for a component and electrical contact means. It is thus possible, thanks to the invention, to obtain a rigid structure that can be handled autonomously, without the aid of a substrate such as those generally used in conventional microelectronics; a transistor is produced, the source and drain contacts of which are each at one of the ends of the second pore, respectively, and a gate contact is produced by depositing a conducting material on the surface layer; the support material is in the form of a portion of a wire, called hereafter a “support wire”, extending longitudinally parallel to the second direction. This is a completely novel form which permits a three-dimensional approach to the preparation of electronic components. Thus, at least one degree of freedom is gained in the operations carried out for fabricating these components compared with what is imposed by the planar geometry of components on a substrate. Furthermore, the diameter of the support wire can be easily controlled, down to dimensions close to a few microns, by electropolishing; a plurality of pores, including the first pore, are formed, each extending substantially over the thickness of a surface layer of the support wire, radially, i.e. perpendicular to the second direction. In other words, the first anodized layer is thus formed. This surface layer can then be converted into a suitable dielectric in order to constitute the gate of a transistor. For example, if the source and drain contacts are each located at one of the ends of the second pore respectively, a gate contact may be produced by depositing a conducting material on the surface layer; at least one active element is enveloped in a matrix comprising the support material; an electrically conducting material is deposited in at least one of the first and second pores; an optically conducting material is deposited in at least one of the first and second pores; a thermally conducting material is deposited in at least one of the first and second pores; at least one line of a material chosen from an electrically conducting material, a thermally conducting material and an optically conducting material is produced on the surface of the support material, in order to connect the active element to an external element; and the process involves a number of treatment operations carried out on the support material, all of the same nature, for example it comprises at least three treatment steps in liquid medium, including the first anodizing operation, the second anodizing operation and an electrodeposition step. These treatment steps may be implemented under relatively unrestrictive operating conditions. This has the advantage over conventional processes for fabricating microelectronic components of making it easier to implement the processes for fabricating these components. This is because the conventional processes involve a number of operations that are now well known to those skilled in the microelectronics art, such as thin-film deposition on a substrate, photolithography operations, microetching, etc. These operations require relatively complicated means, employed in clean rooms and using deposition and/or etching machines operating under ultrahigh vacuum. These processes are therefore relatively costly and are, and will continue to be, more costly as the size scale of the electronic components continues to decrease. Furthermore, in certain methods of implementing the invention, in which the structuring of the component is essentially imposed by a “mold” or a “skeleton” formed by an organized or unorganized network of nanopores, it is possible to completely dispense with the use of lithography operations. Compared to conventional fabrication processes for microelectronic components, these methods of implementing the invention have an economical advantage, as explained above, but also an advantage from the standpoint of the actual physics. This is because, to produce ever smaller components, the wavelengths involved pass from those used in optical lithography to those used in electron lithography. However, the means then employed cannot easily be made compatible with mass production. Now, using the methods of implementing the invention envisaged here, the structuring scales are essentially imposed by the chemistry and/or electrochemistry of the treatments carried out, which treatments act at the molecular level. This is therefore an alternative approach to the conventional processes, which consists in structuring electronic components from elementary nanobricks, such as atoms, aggregates, nanoparticles, nanotubes, nanorods, etc. This approach is called a “bottom-up” approach with respect to the scale of the elementary nanobricks. Processes of the prior art using the “bottom-up” approach are known. For example, nanostructures are produced from elementary bricks using tips of atomic force or scanning tunneling microscopes, or by self-assembly in media of the sol-gel type, by electrodeposition, catalytic growth on a nanocatalyst, etc. Certain methods of implementing the invention presented above aye similar, by analogy, to organization on the basis of a skeleton since, by its organizational structure, a skeleton imposes a functional assembly of the various elements of which it is composed and gives the assembly a rigid mechanical structure. Within the context of the invention, a rigid structure is also formed that imposes the organization or self-organization, during their growth, of elementary nanobricks, while still allowing, by its mechanical rigidity, subsequent handling. In particular, such structuring does not, however, have the drawbacks of nanostructuring using atomic-force or scanning-tunneling microscope tips, which does not seem at the present time to be compatible with a process for the mass production of electronic components. Nor do the methods of implementing the invention have the drawbacks of the structuring techniques involving self-assembly, which experience difficulties due to the lack of reproducibility and to the handling of the objects formed by self-assembly. Furthermore, the connections of the self-assembled objects to conventional electronic circuits require the use of the abovementioned conventional microelectronic techniques, and therefore have the aforementioned drawbacks. According to another aspect, the invention relates to an electronic component obtained by the abovementioned process. According to one embodiment, this component comprises an element of support material with at least one first pore that extends along a first direction and at least one second pore that extends along a second direction, different from the first direction. According to other embodiments, this component includes one or more of the following provisions: the second pore is at least partly filled with an active material, chosen for example from a conductor, a semiconductor, a superconductor, a magnetic material and a carbon structure. This active material may be transparent to light, and in this case it is for example an organic material; a first electrical contact is produced between the active material and the support material, on the bottom of the second pore; the support material constitutes both a self-supporting structure for the component and electrical contact means; the element of support material is in the form of a support wire portion that extends longitudinally parallel to the second direction. This support wire portion includes, at the second pore, a surface layer consisting of an electrically insulating material and a second electrical contact, radially external with respect to the surface layer, is produced on this surface layer; and the component includes at least one active element connected via the first and second pores to the surface of the support material. Other aspects, objects and advantages of the invention will become apparent on reading the description of several of its exemplary embodiments and/or methods of implementation. The invention will also be more clearly understood with the aid of the drawings, in which: FIG. 1 shows schematically the evolution of a component during various production steps of an exemplary method of implementing the process according to the invention; FIG. 2 shows schematically an example of equipment employed during the anodization steps of the process shown in FIG. 1; FIG. 3 shows schematically the evolution of a component during various production steps of another exemplary method of implementing the process according to the invention; and FIG. 4 shows schematically another exemplary embodiment of a component according to the present invention. A first exemplary method of implementing the process according to the invention is presented below in relation to FIGS. 1 and 2. According to this exemplary method of implementation, the process essentially comprises ten steps, each illustrated by FIGS. 1-1 to 1-10 respectively. The process example presented below is applied to the production of a transistor from a support material 1 consisting of an aluminum wire. This aluminum wire is for example a wire 12 microns in diameter, which is commercially available without any difficulty. A portion a few centimeters in length is obtained from this wire. Optionally, the diameter of this wire portion is adjusted by electropolishing down to less than 1 micron. As an example, the electropolishing is carried out by applying a voltage of +8 volts between the support wire, which is connected to a first electrode 7, and a second electrode 9, as illustrated in FIG. 2. This FIG. 2 shows the support material 1 connected to the first electrode 7. The constituent wire of the support material is placed substantially at the center of and perpendicular to the plane of a loop forming the second electrode 9. The whole assembly, consisting of the support material and the first 7 and second 9 electrodes, is immersed in an electrolyte bath, which is uniformly mixed by a stirrer 11. For the electropolishing, the electrolyte consists of a 25% hydrochloric acid (70% HClO4)/75% ethanol mixture. Under these conditions, the rate of dissolution of the aluminum is approximately 1.5 microns per second. According to a variant, a +20 volts voltage is applied for 10 minutes in an electrolyte consisting of sulfuric acid (70% H2SO4). The rate of anodizing is then about 50 nm/min. As shown in FIG. 1-2, the support material 1 is then anodized in order to form a first network of pores 3 extending essentially radially over the thickness of a surface layer 5. This radial anodizing step employs the arrangement illustrated in FIG. 2. A voltage of +40 volts is applied for 2 to 3 minutes between the first 7 and second 9 electrodes. The electrolyte consists of 0.3 molar oxalic acid. Under these conditions a rate of anodizing of about 200 nm/min is obtained. After this anodizing step, that part of the support material 1 immersed in the electrolyte has a surface layer 5 about 400 nanometers in thickness consisting of alumina Al2O3. Except fox the end 6 of the immersed part of the support material 1, the pores of the first network 3 are oriented essentially perpendicular to the longitudinal axis of the wire. As shown in FIG. 1-3, part of the anodized end of the support material 1 is coated, by cathode sputtering, with a gold film 13. This gold film 13 is about 18 nanometers in thickness. It is intended to form a gate contact for the transistor being fabricated. As shown in FIG. 1-4, an insulator film 15 is applied to the gold film 13. This insulator film 15 is for example a film of varnish. It is intended to protect, at least electrically, the radial part of the surface layer 5 and the gold film 13 during the subsequent steps. As shown in FIG. 1-5, the end 6 is cut off, beyond that part of the surface layer 5 formed at the end tip of the support material 1. Thus, the aluminum is again bare at each longitudinal end of the support material 1. As shown in FIG. 1-6, the support substrate 1 then undergoes an electropolishing step. To give an example, this electropolishing step is carried out with an arrangement like that shown in FIG. 2, under the following conditions: voltage between the first 7 and second 9 electrodes: +8 volts; electrolyte consisting of a 25% hydrochloric acid (70% HClO4)/75% ethanol mixture; for 10 seconds. Under these conditions, about 15 microns of aluminum are dissolved at the end 16. As shown in FIG. 1-7, the support substrate 1 then undergoes a second anodizing operation. To give an example, this second anodizing operation is carried out with an arrangement like that illustrated in FIG. 2, under the following conditions: +40 volts voltage between the first 7 and second 9 electrodes, for 10 to 20 minutes, in an electrolyte consisting of 0.3 molar oxalic acid. Under these conditions, a rate of anodizing of about 200 nanometers per minute is obtained. During this second anodizing operation, a second network 17 of pores is formed. Given that the part immersed in the anodizing electrolyte solution is protected by the insulator film 15, except at the tip electropolished in the preceding step, the pores of the second network 17 are oriented essentially parallel to the longitudinal axis of the support material 1. The internal diameter of these pores may be controlled. For example, it will be possible to obtain pores with an internal diameter between 10 and 50 nanometers, depending on the experimental conditions. Likewise, their length may be controlled, for example between a few nanometers and a few tens of microns. As shown in FIG. 1-8, an active material 18 is formed in the pores of the second network 17. This active material may for example be a semiconductor, a superconductor, a magnetic material or a carbon structure. Several examples of active material 18 are given below, with their respective conditions for electrodepositing them in the pores of the second network 17. Production of gold nanowires: voltage between the first 7 and second 9 electrodes: 0 volts relative to an Ag/AgCl reference electrode (not shown in FIG. 2); electrolyte: 4 grams per liter of AuCl and 100 grams per liter of NaCl. Production of nickel nanowires: voltage between the first 7 and second 9 electrodes: −1 volt relative to an Ag/AgCl reference electrode (not shown in FIG. 2); electrolyte: 120 grams per liter of NiSO4 and 30 grams per liter of H3BO3. Each pore of the second network 17 then comprises a nickel nanowire 10 to 50 nanometers in diameter and 0.4 to 50 microns in length. Production of copper nanowires: voltage between the first 7 and second 9 electrodes: −0.3 volts relative to an Ag/AgCl reference electrode (not shown in FIG. 2); electrolyte: 30 grams per liter of CuSO4 and 30 grams per liter of H3BO3. Production of cobalt nanowires: voltage between the first 7 and second 9 electrodes: −1 volt relative to an Ag/AgCl reference electrode (not shown in FIG. 2); electrolyte: 120 grams per liter of CoSO4. Production of copper oxide (Cu2O) nanowires: voltage between the first 7 and second 9 electrodes: −0.3 volts relative to an Ag/AgCl reference electrode (not shown in FIG. 2); electrolyte: 5 grams per liter of CuSO4 and 70 grams per liter of pyrophosphate, pH=11. Production of selenium nanowires: voltage between the first 7 and second 9 electrodes: −0.7 volts relative to an Ag/AgCl reference electrode (not shown in FIG. 2); electrolyte: 5 grams per liter of SeO2 and sulfuric acid (10% H2SO4). Production of tellurium nanowires: voltage between the first 7 and second 9 electrodes: −0.7 volts relative to an Ag/AgCl reference electrode (not shown in FIG. 2); electrolyte: 2 grams per liter of TeO2 and sulfuric acid (10% H2SO4). Production of zinc oxide nanowires: voltage between the first 7 and second 9 electrodes: −0.45 volts relative to an Ag/AgCl reference electrode (not shown in FIG. 2); electrolyte: 0.03 molar ZnNO3. Production of polypyrrole nanowires: voltage between the first 7 and second 9 electrodes: +0.85 volts relative to an Ag/AgCl reference electrode (not shown in FIG. 2); electrolyte: 0.1 molar pyrrole and 0.1 molar LiClO4. As shown in FIG. 1-9, an insulator 23, similar to the insulator 15, is deposited on the end 6. A contact 19 is then electrodeposited at the end 6 of the support material 1. For example, this contact is made of copper. To give an example, the copper electrodeposition conditions may be the following: voltage between the first 7 and second 9 electrodes: −0.3 volts, in an electrolyte consisting of 30 grams per liter of CuSO4 buffered with 30 grams per liter of H3BO3 having a pH of 3.6. The nickel nanowires of the active material 18 then constitute the drain of a transistor 100 (see FIG. 1-10). These nanowires are in electrical contact with the aluminum of the support material 1 at an interface 21. A gate voltage may then be measured, between the support material 1 and the gold film 13 constituting the gate electrode, while a current is being applied on either side of the drain, between the contact 19 and the rest of the support material 1, at the interface 21. According to variants, the active material 18 consists of: a transparent semiconductor obtained by the process described in “Growth of ZnO nanowires by electrochemical deposition into porous alumina on silicon substrates” by S. U. Yuldashev, S. W. Choi, T. W. Kang and L. A. Nosova, Journal of the Korean Physical Society 42, S216-218, Suppl. February 2003; or “Room-temperature ultraviolet light-emitting zinc oxide micropatterns prepared by low-temperature electrodeposition and photoresist”, by M. Izaki, S. Watase and H. Takahashi, Applied Physics Letters 83(24), pp 4930-4932, Dec. 15, 2003; silicon nanowires obtained by the process described in “Template-directed vapor-liquid-solid growth of silicon nanowires” by K. K. Lew, C. Reuther, A. H. Carim, J. M. Redwing and B. R. Martin, Journal of Vacuum Science and Technology 20(1), pp 389-392, January 2002; diodes obtained using the growth process described in “Electrochemical fabrication of cadmium chalcogenide microdiode arrays” by J. D. Klen, R. D. Herrick, D. Palmer, M. J. Sailor, C. J. Brumlik and C. R. Martin, Chemistry of Materials 5(7), pp 902-904, July 1993; carbon nanotubes produced using the growth process described in “Coulomb blockade in a single tunnel junction directly connected to a multiwalled carbon nanotube” by J. Haruyama, I. Takesue and Y. Sato, Appl. Phys. Lett. 77, 2000, p. 2891 or in “Spin dependent magnetoresistance and spin-charge separation in multiwall carbon nanotubes” by X. Hoffer, Ch. Klinke, J-M. Bonard and J-E. Wegrowe, Cond. Mat./0303314; and an organic semiconductor obtained by the process described in “Self-assembly and autopolymerization of pyrrol and characteristics of electrodeposition of polypyrrole on roughened Au (111) modified by underpotentially deposited copper” by Y-C. Liu and T. C. Chuang, Journal of Physical Chemistry B 104, pp 9802-9807, 2003. Another inspiration for the deposition of metal nanowires in the pores of the second network 17 may be the growth process described in “Template synthesis of nanowires in porous polycarbonate membranes: electrochemistry and morphology” by C. Schonenberger, B. M. I. Vanderzande, L. G. J. Fokkink, M. Henny, C. Schmid, M. Kruger, A. Bachtold, R. Huber, H. Birk and U. Stoufer, Journal of Physical Chemistry B 101 (28), pp 5497-5505, 10 Jul. 1997. Numerous variants may be envisaged in the electrodeposition or solution deposition of the active material 18. Carbon nanotubes may be deposited by chemical vapor deposition, at 600° C. and under 20 millibars of acetylene. Silicon nanowires may be deposited by vapor deposition at 500° C., using SiH4, under 0.65 torr, etc. In a second exemplary method of implementing the process according to the invention shown in FIGS. 3-1 to 3-12, a process essentially similar to that described in relation to FIGS. 1-1 to 1-10 is employed, except for the electropolishing first step. This is because, during this electropolishing first step, a support wire 120 microns in diameter is tapered down so as to obtain a tip with a diameter of less than 5 microns. This method of implementation illustrates the possibilities of integrating electronic components afforded by the process according to the invention. The various steps of the process corresponding to FIGS. 3-2 to 3-9 correspond to those illustrated by FIGS. 1-1 to 1-8, respectively. As shown in FIG. 3-10, an insulator 23 is deposited on the end 6. As shown in FIG. 3-11, a contact 19 is then electrodeposited on the end 6 of the support material 1 (FIG. 3-11 and the corresponding step are similar to FIG. 1-9 and the step that it illustrates). The arrangement shown in FIG. 3-12 is similar to that in FIG. 1-10. Another exemplary embodiment of a component 100 according to the present invention is shown in FIG. 4. This component 100 comprises active elements 50. These active elements 50 are nanoelectronic elements. They include nanoscale terminations 51 for electrically and/or thermally and/or optically connecting them to a macroscopic interface. According to one exemplary method of implementing the process according to the invention, these active elements 50 are integrated into a matrix 52 at least partly formed from a support material 1. This support material 1 is for example aluminum. The active elements 50 are prepositioned on a receiving structure (not shown) before being enveloped by the support material 1. A mask (not shown) is then produced on the faces of the matrix 52, for example using known photolithography techniques. The matrix 52 is then anodized, for example using one of the ways indicated in relation to the above methods of implementation. Thus, at least two anodizing operations are carried out in order to form pores in the first and second directions respectively. These pores 17 make it possible to reach the nanoscale terminations 51. An active material 18 is then deposited, for example by electrodeposition, in the pores 3, 17. The choice of the value of the electrolytic potential and its orientation, during this electrodeposition step, allows the active material 18 to be selectively deposited in certain pores 3, 17, for example those actually joining a nanoscale termination 51. The ends of the pores 3, 17, which emerge on the surface of the matrix 52, are optionally connected by means of tracks 53 intended for a connection to a macroscopic interface. These tracks 53 themselves may be produced on the surface of the matrix 52 on a larger scale than that of the nanoscale terminations 51. In particular, they may be submicroscale or microscale tracks produced by optical lithography processes known to those skilled in the art. Tracks 53 may be produced on all the faces of the component 100. Some of these tracks 53 may be dedicated to thermal conduction and thermal coupling, while others may be dedicated to electrical conduction and electrical connection and/or while yet others may be dedicated to optical conduction and optical connection. For example, certain tracks allow an active element, such as a transistor of a memory unit, to be electrically contacted by its “world lines” and/or “read lines”, while this same active element 50 may be thermally coupled to a heat bath. If the active element 50 is a Peltier element, this may be connected to a battery. Optical sensors may also be placed directly on the surface of the matrix 52. In this way, it is possible to remove the heat generated by an active element 50 or, on the contrary, to produce an electric current from temperature differences.

20070523

20100803

20071206

73383.0

H01L5130

CARLEY, JEFFREY T.

PROCESS FOR FABRICATING ELECTRONIC COMPONENTS AND ELECTRONIC COMPONENTS OBTAINED BY THIS PROCESS

UNDISCOUNTED

ACCEPTED

H01L

ACCEPTED

Process for the Treatment of Substrate Surfaces

The present invention relates in general terms to the treatment or processing of substrate surfaces. In particular, the invention relates to processes for modifying the surface of silicon wafers.

1. A process for treating one side of silicon waters in a liquid bath, characterized in that the undersideof the silicon wafers is treated in the liquid bath without the top side previously having been protected or masked. 2. The process as claimed in claim 1, characterized in that the silicon wafers are processed continuously in a once-through process. 3. The process as claimed in claim 2, characterized in that the undersides of the silicon wafers are lowered into the liquid bath. 4. The process as claimed in claim 1, characterized in that as part of a production line the silicon wafers are conveyed horizontally through the treatment liquid located in the liquid bath. 5. The process as claimed in claim 4, characterized in that the liquid bath used is a tank whose peripheral edge is lower than the level of the treatment liquid. 6. The process as claimed in claim 1, characterized in that the edges of the silicon wafers are also treated. 7. The process as claimed in claim 1, characterized in that the treatment is an etching step and is carried out in a liquid composition which contains NaOII, KOH, HF, HNO3, HF with O3, and/or HF with oxidizing agent, such as for example oxidizing acid. 8. The process as claimed in claim 7, characterized in that the oxidizing agent is an oxidizing acid. 9. The process as claim in claim 7, characterized in that the liquid composition contains at leastone additive for binding the gases formed during the etching. 10. A process for treating one side of silicon wafers, characterized in that as part of a production line the wafers are conveyed horizontally through a treatment liquid located in a liquid bath, with the underside of the wafers being treated without the top side having previously been protected or masked. 11. The process as claimed in claim 10, characterized in that the undersides of the silicon wafers are lowered into the liquid bath over the production line. 12. The process as claimed in claim 10, characterized in that the silicon wafers are conveyed horizontally through the treatment liquid located in the liquid bath over the production line. 13. The process as claimed in claim 12, characterized in that the liquid bath used is a tank whose peripheral edge is lower than the level of treatment liquid. 14. The process as claimed in claim 10, characterized in that the production line comprises a multiplicity of conveyor rolls. 15. The process as claimed in claim 14, characterized in that the conveyor rolls are in each case arranged on axle elements. 16. The process as claimed in claim 15, characterized in that each axle element is encapsulated in a fluid-tight manner with respect to the treatment liquid. 17. The process as claimed in claim 10, characterized in that the edges of the silicon wafers are also treated. 18. The process as claimed in claim 8, characterized in that the liquid composition contains at least one additive for binding the gases formed during the etching.

The present invention relates in general terms to the treatment or processing of substrate surfaces. In particular, the invention relates to processes for modifying the surface of silicon wafers. During the production of silicon slices, silicon plates or wafers for the semiconductor and solar cell industry, the wafers are subjected to a range of mechanical and/or chemical treatment steps in order to impart the desired sizes and product properties to them. The text which follows describes the process steps for producing solar cells which are customary according to the prior art. First of all, a silicon ingot is cut into slices, also known as wafers, using a wire saw. After they have been cut, the wafers are cleaned in order to remove what is known as a sawing slurry. This is generally followed by a wet-chemical saw damage etch using suitable chemicals, such as in particular lyes, in order to remove the defect-rich layer which results from the cutting process. The wafers are then washed and dried. The wafers or substrates are generally monocrystalline or polycrystalline silicon waters which are p-doped with boron. To produce a p n junction required for the solar cell to function, one side of the silicon wafers is n-doped. This n-doping is usually carried out by means of phosphorus doping. In the process, the substrate or silicon surface is modified by the incorporation of phosphorus atoms, the phosphorus source used generally being a gas or a liquid-pasty composition. After suitable incubation or coating of the silicon wafers in the gas or with the composition, the phosphorus atoms diffuse into, accumulate on or are incorporated into the silicon surface by heating to usually 800 to 1000° C. After this phosphorus doping, the silicon plate has a layer which is up to a few μm thick and is n+-doped with phosphorus. One problem with this surface modification is that generally not only the desired surface (top side) but also the opposite surface (underside) and in particular the peripheral edges of the substrate waters are modified or doped by the treatment, which in subsequent use leads to the risk of short circuits, since the edges are electrically conductive. Additional doping of the underside, as is effected for example by vapor phase doping, however, is in many cases acceptable, since the n+ doping of the undersides or back surfaces of the plates is then generally converted into a p doping, as is required, for example, for the subsequent contact-connection of a solar cell, by the formation of an “aluminum back surface field”. However, wafers which have been treated in this manner always have edges which include phosphorus atoms and are therefore electrically conductive, which without further treatment leads to silicon wafers having the abovementioned drawback of a risk of short circuits forming in subsequent use. The prior art has developed various processes for eliminating this problem. By way of example, the problem of the electrically conductive edges is solved by the edges being ground away mechanically. However, the grinding, like the sawing, can produce detects in the crystal structure, leading to electrical losses. However, the main drawback of this procedure consists in the considerable risk of the sensitive wafers breaking. Furthermore, it is proposed that the conductive layer which is present on the underside or back surface be interrupted in the outer region or at the edge by the action of a laser beam. However, this edge isolation by means of a laser is not yet an established process and throws up problems in particular with regard to the automation of the process and the throughput which can be achieved. Furthermore, there is a risk that subsequent process steps and the efficiency of, for example, a correspondingly produced cell may be adversely affected by accumulation of combustion products formed during the laser treatment on the wafer surface. Finally, it is proposed that a plurality of plates be stocked and the edges of the plate stock be etched by means of plasma. The edge isolation by means of plasma requires the wafers to be stacked on top of one another. Both the stacking and the handling of the stacks take place either manually or in automated fashion, which involves a very high level of outlay on equipment. Consequently, processing in stacks always involves interrupting or reorganizing the production flow, specifically both in the context of batch production, in which the wafers arc transported in process carriers, and in the case of inline production, in which the wafers are passed through the various process steps on conveyor belts or rolls, etc. Furthermore, the complex handling means that the wafers are once again exposed to an increased risk of breaking. Another process in which only the edges are treated is proposed in DE 100 32 279 A1. DE 100 32 279 A1 describes a process for the chemical passivation of edge defects in silicon solar cells by etching out the edge defects. For this purpose, an etchant is applied to the edges of the silicon solar cells using a felt cloth impregnated with etchant. Further processes which are known from the prior art solve the problem of the electrically conductive edges by removing the conductive layer on the edges and one side of the substrate by means of etching in an acid bath. By way of example, DE 43 24 647 A1 and US 2001/0029978 A1 describe a multistage etching process in which a substrate is completely immersed in an acid bath. Since it is only the back surface and the edges of the substrate which are being etched here in each case, the front surface of the substrate has to be protected by an acid-resistant photoresist or a mask. In particular, the etching process described in DE 43 24 647 A1 and US 2001/0029978 A1 is not just time-consuming, since special working steps are required for the application and removal of protective layers, but also requires the use of additional materials. In particular, the application and removal of protective layers entails the risk of the substrates which are to be treated being adversely affected. Should a protective layer applied be defective or damaged, there is a risk of the front surfaces of the substrates being damaged during etching, so that the substrates become unusable. Therefore, all these processes which have been described in the prior art serve to decouple the two surfaces (top side and underside) in terms of their electrical conductivity, but they involve the in some cases serious problems of the type described above. Therefore, the object of the present invention is to provide a process for treating one side of silicon wafers in which it is possible to make do without the process steps of the prior art involving protecting or masking the front surfaces or top sides which are not to be treated, yet the process can preferably be carried out in a production line. According to the invention, it has been found that it is possible to selectively treat just one of the two surfaces of a substrate. A treatment of one side in this manner comprises, for example, an etching, coating or cleaning of one of the two surfaces. According to one embodiment, it is possible, for example, for just the top side or underside of a corresponding substrate, such as a silicon wafer, to be modified by etching, so that the problem of the formation of short circuits is eliminated in a simple way. To improve understanding, the following text refers to etching of a surface as an example of a treatment of one side of a substrate. According to a particularly preferred embodiment, the process according to the invention is carried out as part of a continuous processing, in which undersides of the substrates, such as in particular silicon wafers (if desired including the peripheral edges) are wetted with an etching liquid located in a liquid bath. It should be noted that the process according to the invention is suitable in particular if it is desired or necessary to treat just one side of a substrate. According to a preferred embodiment, the process according to the invention provides for the substrate, preferably in the form of a silicon water, after the phosphorus doping, to be fed to a single-side etch to remove the phosphorus-doped layer. This is effected by virtue of the fact that just one side of the silicon wafer is completely or partially brought into contact with a liquid composition, which preferably contains NaOH, KOH, HF, HNO3, HF with O3, and/or HF with oxidizing agent, such as for example oxidizing acid. For this purpose, the silicon wafer is oriented substantially horizontally, and the side which is to be etched is wetted with an etching liquid located in a liquid bath. The distance between the etching liquid and the underside of tine silicon wafer is selected to be such that the side of the substrate which is to be etched (if desired including the peripheral edges) is wetted, but the opposite side is not. It should be noted that this etching step is preferably performed directly after the phosphorus doping, since the phosphorus glass etching is generally carried out by wet-chemical means and the edge isolation according to the invention can then be carried out in the same installation, which saves space and is an inexpensive solution. However, it will be clear to the person skilled in the art that the step according to the invention can also be carried out at other times. The only important factor is that the etch according to the invention should take place prior to the application of the metallic contacts to the back surface or underside of a given substrate. According to one preferred embodiment of the process according to the invention, both one side of the substrate and the peripheral edges of the substrate can be treated in the manner which has boon outlined above. According to one embodiment, the substrates are lowered into a liquid bath containing a liquid composition, in which case the extent to which they arc lowered can easily be set by the person skilled in the art as a function of the thickness, weight and surface properties of the substrate and the surface tension of the liquid composition. Moreover, by accurate setting of, for example, the level in the treatment bath, it is possible for not just the underside but also the edges to be treated, which is particularly preferred according to the invention. It will be clear to the person skilled in the art that the treatment according to the invention can be carried out not only by lowering into a liquid bath but also in other ways, provided that it is ensured that it is actually only one side, and if appropriate also the edges, that are wetted by the etchant and modified as a result. By way of example, according to a further embodiment it is possible to provide two vessels of different size, the smaller vessel containing the liquid composition and being surrounded by the larger vessel. The smaller vessel is filled to the brim with the liquid and is fed by virtue of being connected to the larger vessel. This supply of liquid may, for example, take place continuously by means of a pump and can be set in such a way that a certain quantity of the etching liquid always overflows into the outer tank (the larger vessel), the liquid being pumped back from there preferably into the inner tank (the smaller vessel). The pumping of the liquid composition means that the liquid level is always slightly higher than the peripheral edge of the smaller vessel, the difference between the level of the liquid and the height of the container edge being dependent, inter alia, on the surface tension of the etching medium used. Using this arrangement, it is readily possible for the wafers which are to be treated to be conveyed horizontally over the liquid as part of a production line, so that the underside of the wafers is wetted without there being any possibility of the waters banging into the side walls of the smaller inner vessel and being damaged. Alternatively, it is possible to employ dipping processes, in which case the liquid level in the bath is set to be sufficiently low for the underside of the wafers, if appropriate including the edges, to be wetted only when it is at the lowest point of the dipping curve. It should be noted that the wetting or treatment of a single side of a substrate which is proposed in accordance with the invention in the embodiments described above can be achieved or assisted in various ways, with a fundamental distinction being drown between active (direct) and passive (indirect) wetting. In the context of the invention, active or direct wetting is to be understood as meaning that the desired treatment of one side of the substrate is ensured directly by the substrate being passed through the treatment liquid. According to the invention, this requires the level of the substrate underside which is to be treated to be at least for a brief period below the maximum level of the treatment liquid. In the context of active wetting, by way of example, the substrate can be lowered into the liquid or the level of the liquid in the tank can be completely or partially raised, the invention also encompassing a combination of lowering of the substrate and raising of the level of the liquid. By way of example, the surface of the bath can be locally raised by a correspondingly arranged and directed liquid inlet below the surface at the location at which the substrates arc introduced into the bath. Furthermore, the bath surface can be partially raised by blowing in gas bubbles below the substrate, e.g. using compressed air, so that it is likewise possible to ensure wetting of the substrate underside. By contrast, in the context of the invention passive or indirect wetting is to be understood as meaning that the underside of the substrate which is to be treated is above the level of the liquid throughout the entire duration of the treatment, and consequently wetting is effected only indirectly by means of components of the system which for their part are in contact with the liquid and are responsible for welling the substrate undersides. In this context, it should be noted that the substrate side which is to be treated needs to be wetted either completely (over its entire surface) or just partially through contact with the component responsible for the welling, since the hygroscopic properties of the surface of silicon wafers ensure that even partial wetting of the underside by a component leads to wetting of the entire surface within a very short time. With regard to the components which can be provided for the indirect wetting, it should be noted that these may either form part of the conveyor system explained above or may be arranged in the liquid bath, in such a manner that they at least in part project out of or can be extended out of the liquid. Accordingly, according to the invention fixed, rotating or vertically displaceable components are equally suitable. It is preferable for the surface property and/or shaping (e.g. by exploiting a capillary effect) of the component to ensure that its region which is intended to come into contact with the substrate underside is wetted and effects the wetting of the surface to be treated without the substrate itself coming into contact with the liquid bath. By way of example, the component may be a wetting roller which rotates in the liquid of the bath and, as a result of the rotary motion, takes up etching liquid, with which the substrate undersides located above the level are then wetted. As has already been explained, it is, however, also possible, in accordance with the invention, to use components of other configurations, such as (vertically displaceable) tables, pins or rams, since surprisingly even punctiform contact with the substrate underside is sufficient to ensure wetting of the entire surface. The use of a conveyor system for guiding the substrates which are to be treated as part of the process according to the invention in principle allows both active and passive wetting. In the case of active wetting, the substrate to be treated is guided through the liquid, whereas passive wetting is effected by correspondingly configured components of the conveyor system. The suitability of examples of conveyor systems in accordance with the invention is explained in more detail below with additional reference to FIG. 1. According to one embodiment of the present invention, the substrates are laid on a conveyor system, such as for example a roller conveyor system. In this case, the substrates arc conveyed with the aid of a plurality of conveyor rolls (1) arranged one behind the other and oriented horizontally. In the context of the active wetting as defined above, the individual conveyor rolls are preferably arranged in such a manner in a liquid bath that in each case the upper edge of the rolls is located approximately at the level of the bath surface, i.e. of the upper edge of the liquid, so that the underside of the substrate is wetted through direct contact with the bath surface. In this case, a meniscus may form at the substrate edges. The interplay of gravity and surface tension then draws the substrate downward and ensures that it remains in contact with the rolls without floating. This allows controlled and defined conveying of the substrates using the roll conveyor sys tern. In this context, it is important that it be possible for the height of the liquid bath to be set so accurately with respect to the conveyor system that it is possible for the underside and if appropriate the edges of the substrates to be wetted without the top sides of the substrates also being wetted. Also, the configuration of the conveyor system must allow contact between the substrates and the liquid in the liquid bath. According to a particularly preferred embodiment, there are at least two support elements (3), which may advantageously be disposed on the conveyor roll in the region of two grooves (2), present on the conveyor roll (1). The distance between the support elements is predetermined by the width of the substrates which are to be treated. In the context of the active wetting, the above statements relating to the positioning of the conveyor rolls in this embodiment apply to the support elements. In the context of the passive wetting as defined above, the conveyor rolls themselves or the support elements are responsible for complete or partial wetting of the substrate undersides. The conveyor roll is preferably of at least two-part structure, comprising an axle element and at least one track element surrounding the axle element. The axle element may function either purely as a stabilizer or as a stabilizing bearing. It is preferably a bearing axle. The material of the axle, which does not come into contact either with the material being conveyed or with a chemical environment which may under certain circumstances be aggressive, can be selected purely on the basis of mechanical and thermal aspects. According to the invention, it is flexurally rigid. By contrast, the track element is permitted certain thermal tolerances on account of the stabilizing bearing axle. The crucial factor for the material is that it does not react either with the piece material or with the ambient medium. The flexurally rigid bearing axle ensures that the material being conveyed is held on a stipulated straight line in the direction perpendicular to the conveying direction. As a result, the conveyor roll runs synchronously over its entire length, which is important in particular in the case of relatively wide conveyor rolls with a plurality of conveyor tracks and for flat material being conveyed which is sensitive to fracturing. In one preferred embodiment, the axle element is made from a carbon fiber composite. Carbon fiber composites have a high thermal and mechanical stability and are therefore particularly suitable for use as bearing axles employed at fluctuating temperatures. In one preferred embodiment, the bearing axle is encapsulated, for example by sealing rings, with respect to the medium which is used to treat the material being conveyed. The medium, which according to the invention is a wet-chemical bath, then only comes into contact with the exterior of the track elements and the liquid medium cannot penetrate into the interior of the track elements, onto the bearing axle or onto any fixing elements which may be present between bearing axle and track elements. The seal may be liquid-tight or may even be designed to a certain degree to be gas tight, so that it is also impossible fox harmful vapors to penetrate into the interior of the track elements. The track elements can be assembled in any desired length, and a conveyor roll may, for example, comprise an axle with any desired number of track elements. A conveyor roll manufacturer or supplier can meet customer requirements very flexibly without having to employ complicated stock management. The track element, since it con be used for conveyor rolls of any length, is a mass-produced article, which reduces its production costs. The track elements can, for example, be plugged together, screwed onto one another, connected using a clip or welded to one another. In a preferred embodiment, the substrate to be treated is actually supported on support elements (3) with static friction properties which are suitable for the workpiece, in which case the support elements, as mentioned, can be used not only for conveying but also for passive wetting. These elements should likewise be thermally and chemically stable. The use of O rings made from fluorinated rubber has proven suitable for the production of solar cells. Since the diameter spanned by the support elements is greater than the remainder of the track element, the material being conveyed experiences only punctiform contact and if appropriate wetting. This, unlike linear contact, is gentle on the material being conveyed and at the same time ensures good contact with the surrounding medium. In a further advantageous embodiment, the track element is made from plastic. It is known that plastic is easy to process and offers a wide range of different properties which are selected according to the use and deployment location of the conveyor roll. By way of example, it has proven expedient to use polyethylene, polyfluoroalkoxide or polyvinylidene fluoride. These materials are thermally stable up to oven 80 degrees Celsius, are weldable, have a certain chemical stability, do not cause any metal contamination and are relatively unabraidable. An advantageous refinement of the invention consists in track elements being driveable, i.e. it is possible for the drive to be applied not to the bearing axle and then transmitted from the latter to the track elements, but rather for it to act directly on the track elements. Conveyor rolls having track elements of this type can be assembled to form particularly synchronous conveyor systems. Optimum traction is transmitted to the material being conveyed. In one embodiment, of an assembled series of track elements, a first edge element has means for transmitting the driving force and a second edge track element has means for rotatable bearing. The drive can be transmitted to the conveyor roll via a coupling element, which is fitted to a drive shaft and can be connected to the first edge track element. The coupling element also has a means for holding the bearing axle. If a conveyor roll is to be .removed from a conveying position, first of all the second edge track element has to be released from the bearing, the entire conveyor roll has to be pivoted about the coupling element and then the conveyor roll has to be removed from the coupling clement. The means for rotatable bearing may comprise an upper and a lower half-shell, the lower halt-shell being fixed to the wall of the conveyor system and being used to support the conveyor roll, and the second, upper half-shell being releasably secured for retaining purposes. The width of the track element advantageously corresponds to at least the width of the workpiece to be conveyed, so that the wide side of a workpiece rests on just one track element. It is preferable for each track element to receive just one workpiece, i.e. for the widths of track element and material being conveyed to be virtually equal. In an advantageous embodiment of the conveyor roll, a fixing ring is fitted to the bearing axle, the internal diameter of a track element at least at one location being smaller than the diameter of the fixing ring. The fixing ring therefore prevents the possibility of a track element executing greater movements on the bearing axle. This is important in particular in the event of temperature changes, if the material of bearing axle and track elements expands differently, which could cause them to move relative to one another. The fixing ring is preferably made from metal, since metal can be successfully bent onto the axle and clamped in place there. For use at different temperatures, slight changes in length should have no adverse effect on the stability of the conveyor roll as a whole. Therefore, in a further advantageous embodiment of the invention, the track elements are provided with a compensation crease at which thermal expansions are compensated for. The compensation crease generally comprises an inner hollow convexity in the material of the track element, which absorbs the temperature-induced material expansion by stretching in the longitudinal direction. If the compensation crease is not located between the support points of the material being conveyed, the stability of support remains stable even in the event of temperature-induced changes in length. If, moreover, the track elements are in each case fixed to the bearing axle, the rectilinear nature of the track is also retained. Uniform guidance of the material being conveyed is ensured particularly successfully if conveyor rolls according to the invention are assembled to form a conveyor system. In one preferred refinement of the conveyor system, each conveyor roll is driven. In this case, each conveyor roil is subject to the same transmission of force and is therefore also subject to equal loads. Since the conveying guidance provided by the conveyor system proposed according to the invention allows a high throughput and at the same time is very gentle on the material being conveyed, it is particularly suitable for use in the context of the process according to the invention. It should also be noted that it is possible to use alternative embodiments of conveyor systems which do not employ conveyor rolls. By way of example, substrates can also be conveyed on a rotating belt, a chain or also cords. A further conveying option in a conveyor system is formed by a traveling bar. This system uses two or more bars which alternately convey the substrates forward. While a first bar is moving forward, a second bar moves backward. In this case, the second bar lies deeper in the liquid bath and is not in direct contact with the substrate. When the first or upper bar has reached the end of its possible conveying movement and the second or lower bar has reached its start, the lower bar is raised, so that the substrates come into contact with both bars. The upper bar is then lowered and can therefore move back to the start of the liquid bath, while the lower bar is executing a forward movement. In conventional designs of a bar conveyor system of this type, the bars are mounted on rotating shafts with an eccentric, i.e. they are constantly moving up and down. However, to ensure treatment of one side of substrates, the substrates, in the context of active wetting, must always remain at the same height. Corresponding modifications to a conventional bar conveyor system and its use in the context of the passive wetting as defined above are, however, immediately apparent to a person skilled in the art having knowledge of the present description. Therefore, the process according to the invention can particularly advantageously be carried out in a once-through installation, since in the context of an inline production of this type there is no need for any additional handling step for the wafers. Furthermore, the back surface/edge isolation according to the invention can be carried out together with the oxide etching in the same installation, making the process sequence simpler and less expensive. Furthermore, by using the process according to the invention it is also possible to realize cell concepts in which the back surface of the cell docs not have a full-area “aluminum back surface field” (AlBSF). Since in the process according to the invention the n doped layer on the back surface of the cell is completely removed, it is no longer imperative that this doping be compensated for by forming an AlBSF in order to form a p-doped zone. This leaves open more options with regard to the configuration of the back surface of the cell and simplifies realization of cell concepts without AlBSF. Depending on the particular process (continuous or discontinuous), the liquid composition may require additives, for example to avoid or reduce the size of gas bubbles, in which case additives of this type can be selected by the person skilled in the art without difficulty on the basis of the specific requirements. When selecting suitable additives, in particular in the once-through process, it should be ensured that the wafers do not acquire excessive buoyancy as a result of possible formation of gas bubbles, which could have an adverse effect on efficient conveying, since the wafers may lose contact with a corresponding conveyor means as a result. Consequently, according to a preferred embodiment it is proposed that the etching solution contain at least one additive which is able to substantially bind the gases termed during the chemical reaction, so that the formation of gas bubbles on the underside of the wafers is substantially suppressed. It should be noted that the process according to the invention can be employed not only for the electrical isolation of the two sides of wafers or solar cells, but is also suitable for carrying out other wet-chemical treatments in which treatment of one side of a substrate with a liquid medium is required or desired, such as for example in the case of cleaning and coating.

20060922

20110517

20080925

98115.0

H01L21302

ANGADI, MAKI A

PROCESS FOR THE WET-CHEMICAL TREATMENT OF ONE SIDE OF SILICON WAFERS

UNDISCOUNTED

ACCEPTED

H01L

ACCEPTED

Method of Diagnosing Apoplectic Stroke/Asymptomatic Brain Infarction Using Polyamine and Acrolein Contents, Polyamine Oxidase Activity or Protein Content Thereof as Indication

The present invention provides a diagnostic method for stroke/asymptomatic cerebral infarction and a screening method for patients with stroke/asymptomatic cerebral infarction, which comprise measuring acrolein content or polyamine content; or polyamine oxidase activity or protein content of polyamine oxidase in plasma. The knowledge of the present invention indicates the possibility of preventing, inhibiting the progression of stroke/asymptomatic cerebral infarction by inhibiting polyamine oxidase, and the possibility of obtaining a therapeutic agent for stroke/asymptomatic cerebral infarction by searching for compounds that inhibit polyamine oxidase.

1. A diagnostic method for stroke/asymptomatic cerebral infarction, comprising: sampling biological sample from subject; measuring polyamine content or aldehyde compound content formed from the polyamine in the sample; or polyamine oxidase activity or protein content of polyamine oxidase in the sample; and diagnosing stroke/asymptomatic cerebral infarction using the measured value obtained as an indicator. 2. The method according to claim 1, wherein said polyamine is spermine, spermidine or putrescine. 3. The method according to claim 1, wherein said aldehyde compound formed from the polyamine is acrolein. 4. A screening method for patients with stroke/asymptomatic cerebral infarction, comprising: sampling biological sample from subject; measuring polyamine content or aldehyde compound content formed from the polyamine in the sample; or polyamine oxidase activity or protein content of polyamine oxidase in the sample; and screening for patients with stroke/asymptomatic cerebral infarction using the measured value obtained as an indicator. 5. The method according to claim 4, wherein said polyamine is spermine, spermidine or putrescine. 6. The method according to claim 4, wherein said aldehyde compound formed from the polyamine is acrolein. 7. The method according to any one of claims 1 to 3, wherein statistically significant change in said polyamine oxidase activity or said protein content of polyamine oxidase in the biological sample obtained from the subject occurs before characteristic image for the symptom or onset of stroke/asymptomatic cerebral infarction is recognized in the head diagnostic image taken from the subject. 8. The method according to any one of claims 4 to 6, wherein statistically significant change in said polyamine oxidase activity or said protein content of polyamine oxidase in the biological sample obtained from the subject occurs before characteristic image for the symptom or onset of stroke/asymptomatic cerebral infarction is recognized in the head diagnostic image taken from the subject.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diagnostic method for stroke/asymptomatic cerebral infarction using polyamine or acrolein content, polyamine oxidase activity or protein content thereof as an indicator. Furthermore, the present invention relates to a screening method for patients with stroke/asymptomatic cerebral infarction using polyamine or acrolein content, polyamine oxidase activity or protein content thereof as an indicator. 2. Description of the Related Art Cerebrovascular disease is the common cause of death next to malignant neoplasm and cardiac disease, and the annual loss of life number thereof is around 10 times of that of renal disease. Moreover, it causes such a tremendous trouble in daily life, for aftereffect of the disease accompanies paralysis and akinesia for example. Stroke constitutes a majority of the cerebrovascular diseases, and early detection and treatment of the disease are difficult. Furthermore, asymptomatic brain infarction that does not show any subjective symptoms is mostly detected accidentally by diagnostic imaging. So, in present circumstances, there have been no diagnostic markers available in blood or urine examination. Therefore, development of a simple and accurate diagnostic method, which does not require expensive medical equipments such as diagnostic imaging system, has been desired. By the way, polyamine is biogenic amine that exists in the body universally, and spermine, spermidine or putrescine is the representatives. And these polyamines exist in high concentration in cells and act as cell growth factors by interacting with nucleic acids within the body. On the other hand, polyamine produces cytotoxic acrolein (CH2═CH—CHO) during its metabolic process. This acrolein is detoxified by aldehyde dehydrogenase in cells, but it shows intense toxicity when it leaks out of cells. In addition, since polyamine accumulates in the plasma of patients with chronic renal failure, it is assumed that polyamine is one of the causative substances of uremia. Moreover, it is said that it is difficult to remove this polyamine by dialyses thoroughly. Thus, clarification the essence of polyamine-induced toxicity leads to the development of more effective therapeutic agents of uremia. Based on this standpoint, the present inventors tried to inhibit polyamine oxidase, which acts in the pathway for the synthesis of acrolein from polyamine, by using amino guanidine. And as a result, it was confirmed that the polyamine lost its toxicity (Japanese Patent Publication No. 2002-281999). In diseases that involve tissue destruction, it is possible with high probability that polyamine liberated from cells receives oxidative deaminated by polyamine oxidase in plasma, then acrolein is formed in large quantities, so that the formed acrolein is associated with toxicity. SUMMARY OF TUE INVENTION As described above, it was known that acrolein generated by oxidative degradation of polyamine is involved in uremia in kidney diseases. However, there has not been sufficient knowledge on whether acrolein is involved in other cerebrovascular diseases such as stroke. The term “stroke” represents local neuropsychiatric symptoms that occur acutely during the course of a pathologic process of cerebral blood vessel, and cerebral infarction and intracerebral bleeding are fundamental as causative diseases. Therefore, the problem to be solved by the present invention is to examine whether or not some quantitative change occurs in the polyamine or acrolein content. If acrolein content changes in patients with stroke, then diagnosis of stroke/asymptomatic cerebral infarction using acrolein as an indicator will be enabled. Moreover, since polyamine oxidase in plasma is involved in the process of the synthesis of acrolein from polyamine, examination on whether some change in polyamine oxidase activity and protein content thereof occurs or not is also the problem to be solved by the present invention. The present inventors measured the acrolein content, the polyamine content and the polyamine oxidase activity in plasma of the subjects, and then compared on the difference between stroke/asymptomatic cerebral infarction group and healthy group or group of other brain disease. As a result, this study confirmed that acrolein content and polyamine oxidase activity in plasma were obviously high in the stroke/asymptomatic cerebral infarction group, compared with the healthy group or the group of other brain diseases. Further still, the inventors confirmed that infarction is found in subjects with high acrolein content and polyamine oxidase activity in plasma, by taking head tomographic images of the subjects using magnetic resonance imaging (MRI), and thus the present invention was completed. In other words, the present invention provides a diagnostic method for discovering and predicting stroke/asymptomatic cerebral infarction. According to the present invention, by measuring acrolein content, polyamine oxidase activity or protein content of polyamine oxidase, or polyamine content in plasma, stroke/asymptomatic cerebral infarction can be predicted and discovered. The present invention provides a diagnostic method for stroke/asymptomatic cerebral infarction and a screening method for patients with stroke/asymptomatic cerebral infarction by measuring acrolein content, polyamine content, or polyamine oxidase activity or protein content thereof. The knowledge of the present invention indicates the possibility of preventing stroke/asymptomatic cerebral infarction or inhibiting the progression of the diseases by blocking the pathway for the synthesis of acrolein from polyamine in vivo by way of polyamine oxidase mediated oxidative deamination. The knowledge of the present invention further indicates the possibility of obtaining therapeutic agents for stroke/asymptomatic cerebral infarction by searching for compounds that inhibit polyamine oxidase, therefore various application can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing comparison of FDP-lysine content in plasma among the stroke/asymptomatic cerebral infarction group, the healthy group and the group of other brain diseases. FIG. 2 is a graph showing comparison of polyamine oxidase activity in plasma among the stroke/asymptomatic cerebral infarction group, the healthy group and the group of other brain diseases. FIG. 3 is a photograph showing the result of head tomographic image analysis using MRI. FIG. 4 is a photograph examining on the time course of head tomographic image analysis using MRI and CT. BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the inventors found that acrolein, formed by the oxidative degradation of polyamine, exist in blood serum of the patients with cerebral infarction and intracerebral hemorrhage. In addition, the inventors proved that the increase in acrolein content, polyamine content and polyamine oxidase activity could be used as a means for discovering or predicting cerebral infarction and intracerebral hemorrhage. Therefore, the present invention provides a diagnostic method for stroke/asymptomatic cerebral infarction, which comprises sampling biological sample from subject, measuring polyamine content or aldehyde compound content formed from the polyamine in the sample; or polyamine oxidase activity or protein content of polyamine oxidase in the sample, and diagnosing stroke/asymptomatic cerebral infarction using the measured value obtained as an indicator. Also, the present invention provides a screening method for patients with stroke/asymptomatic cerebral infarction, which comprises sampling biological sample from subject, measuring polyamine content or aldehyde compound content formed from the polyamine in the sample; or polyamine oxidase activity or protein content of polyamine oxidase in the sample, and screening for patients with stroke/asymptomatic cerebral infarction using the measured value obtained as an indicator. In the present invention, at first, biological samples for measurement are taken from subjects. Biological samples used in the present invention may preferably be the blood plasma used in the following example. However, other biological samples, such as urine, saliva, cerebrospinal fluid and bone marrow fluid can also be used. The term “polyamine” herein represents a straight-chain aliphatic hydrocarbon having two or more primary amino groups. Known biogenic polyamines may include, but are not limited to, putrescine, cadaverine, spermidine, spermine, 1,3-diaminopropane, caldine, homospermidine, 3-aminopropylcadaverine, norspermine, thermospermine, caldopentamine, and so on. Meanwhile, preferred polyamines in the present invention may be putrescine, spermidine and spermine. The above polyamines are metabolized by oxidation, acetylation, transamination and carbamoylation, and polyamine oxidase is the enzyme that involves in the oxidation of polyamine. The term “polyamine oxidase” herein represents an enzyme that oxidizes diamine or polyamine as a good substrate and generates hydrogen peroxide. Polyamine receives oxidative deamination by polyamine oxidase, thereby aldehyde compounds such as acrolein would be produced. The preferred aldehyde compound in the present invention may be acrolein, but is not so limited to it. The acrolein content in plasma could be determined by measuring the content of FDP-lysine (N-formyl-piperidino-lysine), which is an amino acid adder with acrolein. FDP-lysine content could be measured by using ACR-LYSINEADDUCT ELISA SYSTEM (NOF CORPORATION), for example, according to the attached manual. In addition, acrolein content could be measured in the form of derivatives other than FDP-lysine. Furthermore, it is also possible to measure acrolein content directly, and such procedure is described in a report by Alarcon et al. (Alarcon R. A. (1968) Anal. Chem. 40, 1704-1708), for example. However, the problem is that the reactivity of acrolein with other molecules is so high that the amount of free acrolein in the blood is very little. Thus, considering the measurement of acrolein in the form of FDP-lysine is simple and easy, it is a preferred embodiment in the present invention to measure acrolein in the form of FDP-lysine. Specifically, patient serum and standard solution are dispensed into a plate immobilized with antigen by 50 μl/well, and further the same amount of primary antibody solution is added. The fluid is removed after left at rest for 30 minutes at room temperature and washed by a washing solution, and then 100 μl/well of secondary antibody solution is dispended into the plate. It is washed by the washing solution after left at rest for 1 hour at room temperature, and then color was developed by adding coloring reagent and leaving at rest for 15 minutes at room temperature. The absorbance at 450 nm is determined using a plate reader, and the amount of acrolein in plasma is displayed as the amount of FDP-lysine contained in one ml of patient serum (nmol/ml plasma). The measurement of polyamine oxidase activity can be conducted, as shown in the following examples for example, by incubating 0.15 ml of reaction mixture containing 10 mM Tris-hydrochloric acid (pH 7.5), 0.2 mM substrate (spermine, spermidine and putrescine), and 0.03 ml of patient plasma for 48 hours at 37° C. Trichloroacetic acid (TCA) is added to 0.02 ml of the reaction mixture to a final concentration of 5%, and it is treated by centrifugalization. A part of obtained supernatant is used for polyamine assay. The activity of amine oxidase can be displayed as the amount of spermidine generated by the decomposition of spermine per one ml of patient serum (nmol/ml plasma/48 h). The methods of measuring the enzyme activity of polyamine oxidase are described in various reports, and report by Sharmin et al. (Sharmin et al., (2001) Biochem. Biophys. Res. Commun. 282, 228-235), report by Sakata et al. (Sakata et al., (2003) Biochem. Biophys Res. Commun. 305, 143-149), and report by Igarashi et al. (Igarashi et al., (1986) J. Bacteriol. 166, 128-134) can be cited as the concrete examples. Based on the description of these reports, those skilled in the art can measure the enzymatic activity of polyamine oxidase by making appropriate modifications. Furthermore, protein content of polyamine oxidase can be measured by enzyme-linked immunosorbent assay (EILSA), western blotting analysis or immunoprecipitation method using specific antibody for polyamine oxidase, for example. These methods are heretofore known and commonly used, therefore, those skilled in the art can measure protein content of the enzyme using the above methods by setting appropriate conditions ad libitum. In addition, antibodies to polyamine oxidase used for conducting these measurements can be a monoclonal antibody or a polyclonal antibody. The polyclonal antibody to polyamine oxidase can be obtained by a conventional technique for production of a peptide fragment for example, by immunizing rabbits with the peptide fragment of polyamine oxidase. The production of peptide antibody can be confirmed through assaying whether the antibody has reached to sufficient titer by taking blood from rabbits administered with the peptide and measuring its antibody titer. The methods for producing peptide antibody are described in various experimental manuals and well known among those skilled in the art, so the antibody to polyamine oxidase can be obtained by making various modifications based on those descriptions. The polyamine content in the samples can be measured by high-performance liquid chromatography (HPLC). For example, in cases where polyamine column commercially available from TOSO can be used, retention time of polyamines (putrescine, spermidine and spermine) on the HPLC is 7 minutes, 12 minutes and 25 minutes, respectively. The amount of polyamine can be represented as the amount of putrescine, spermidine and spermine contained in one ml of patient serum (nmol/ml plasma). Further, other normal amino acid columns can be used ad libitum. In the following examples, the presence of infarction was examined by obtaining head tomographic image with magnetic resonance imaging diagnosis (MRI) with the consent of subjects. As a result, as shown in the following examples, evidence of cerebral infarction was shown in the subjects who indicated elevated polyamine levels in the healthy group. Therefore, it was shown in this invention that acrolein content, polyamine content, or polyamine oxidase activity of the cerebral infarction patients in plasma was higher than healthy subjects, and stroke/asymptomatic cerebral infarction could be diagnosed using above measured values as an indicator using the knowledge of this invention. In addition, by utilizing the knowledge obtained in the present invention, the patients of stroke/asymptomatic cerebral infarction can be screened using above measured values as an indicator. For example, by statistical analysis on average and variance of above indicative measured values of the healthy group, upper normal limit of the above measurements are set. Based on those values, it would be possible to diagnose that those subjects showing higher values may be suffering from stroke/asymptomatic cerebral infarction with high probability. Furthermore, the knowledge of the present invention indicate the possibility of preventing stroke and inhibiting progression of the disease, by suppressing generation of acrolein in a living body, through inhibiting polyamine oxidase activity in plasma. This invention thus provides the possibility of developing a new ground for the treatment of stroke. Moreover, by administrating a candidate compound that could be effective in the treatment of stroke to experimental animals and measuring whether the compound has the activity of inhibiting polyamine oxidase in plasma of said animals, it would be possible to search a new medicine effective in the treatment of stroke. Therefore, this invention also provides a new way to search for novel effective medicines for treatment of stroke. EXAMPLES Hereinafter, the present invention will be further concretely described with some examples, but the invention is not so limited within the descriptions. Example 1 Comparison of Acrolein Content in Plasma of Patients with Brain Disorder Acrolein contents in plasmas of patients with brain disorder were examined. The acrolein contents in the obtained bloods were compared among normal healthy subjects, infarction or intracerebral hemorrhage group, and group of other brain disorder. The acrolein content in plasma was determined by measuring FDP-lysine (N-formyl-piperidino-lysine), which is an amino acid added with acrolein. It was measured by using ACR-LYSINEADDUCT ELISA SYSTEM (NOF CORPORATION), according to the attached manual. Patient serum and standard solution were dispensed by 50 μl/well into a plate immobilized with antigen, and further the same amount of primary antibody solution was added. The fluid was left at rest for 30 minutes at room temperature, then it was removed and washed by washing solution. Afterward, coloring reagent was added and it was left at rest for 15 minutes at room temperature for color development. Absorbance was determined at 450 nm by plate reader. The amount of acrolein in plasma was represented as the content of FDP-lysine per milliliter of patient serum (nmol/ml plasma). As shown in FIG. 1, FDP-lysine content that reflects acrolein content in plasma was highest in the infarction or intracerebral hemorrhage group among the above three groups, and the increase was significant compared with other groups. In addition, by comparing with acrolein content in plasma of patients with renal failure, it was revealed that FDP-lysine content of infarction patients increased to the same level as renal failure patients. Example 2 Comparison of Amine Oxidase Activity in Plasma of Patients with Infarction Disorder The polyamine oxidase activity in the plasma of patients used in example 1 was measured. The results are shown in FIG. 2. The polyamine oxidase activity in the plasma was measured by incubating 0.15 ml of reaction mixture containing 10 mM Tris-hydrochloric acid (pH 7.5), 0.2 mM substrate (spermine, spermidine and putrescine), and 0.03 ml of patient plasma at 37° C. for 48 hours, Trichloroacetic acid (TCA) was added to 0.02 ml of the reaction mixture to a final concentration of 5%, and it was treated by centrifugalization. A part of obtained supernatant was used for polyamine assay. The activity of amine oxidase was represented as the amount of spermidine generated by the decomposition of spermine per milliliter of patient serum (nmol/ml plasma/48 h). The polyamine oxidase activity in plasma of infarction or intracerebral hemorrhage group was significantly higher compared with healthy subjects and the group of other brain disorder. This result correlated with acrolein content in plasma examined in example 1. Example 3 Analysis of Head Tomographic Image by Magnetic Resonance Imaging Diagnosis (MRI) The presence of infarction was examined by taking head tomographic image by MRI with the permission and consent of subjects. The MRI tomographic images are shown on healthy subjects (FIG. 3A), patients with brain infarction (FIG. 3B), and subjects with extremely high level of acrolein content and polyamine oxidase activity in plasma whose disease names have not been established (FIG. 3C). As shown in FIG. 3C, in patients with increased level of acrolein and polyamine oxidase activity in plasma, multifocal infarction was found in bilateral frontal, temporal and parietal lobes and basal ganglion. In addition, atrophy and arteriosclerosis of brain were found. Example 4 Comparison of Changes in Head Tomographic Images, Polyamine Oxidase Activity and Acrolein Content in Plasma in Patients in the Acute Stage of Brain Infarction For one patient in the acute stage of brain infarction, changes in head tomographic images (MRI and CT) and the accompanied changes in the polyamine oxidase activity and acrolein content in plasma were analyzed on day 1, day 2 and day 7 after the onset of stroke. The photographs of head tomographic images are shown in FIG. 4. On the day of the onset, definitive evidence of infarction was not found in T2-weighted MRI and CT. On the other hand, the polyamine oxidase activity and FDP-Lys content in plasma on the day of the onset was 6.6 nmol SPD/ml plasma and 18.4 nmol/ml plasma, respectively. These results revealed that plasma polyamine oxidase activity was about twice as high as that of healthy subjects, and significantly high. Definitive evidence of infarction was found in the left temporal lobe in the magnetic resonance imaging (MRI) of the second day of the onset and in the head computed tomography (CT) after one week of the onset. The polyamine oxidase activity and FDP-Lys content in plasma after one week of the onset was 7.2 nmol SPD/ml plasma and 23.0 nmol/ml plasma, respectively. Therefore, along with the increase in plasma polyamine oxidase activity, significant increase in acrolein content in plasma was also recognized. As indicated above, it was confirmed that in patients in the acute stage of brain infarction, the increase in polyamine oxidase activity in plasma precedes the emergence of the infarction image in MRI or CT. INDUSTRIAL APPLICABILITY The method of the present invention, which comprise measuring acrolein content, polyamine content, polyamine oxidase activity or protein content of polyamine oxidase in plasma, is useful for diagnosing stroke/asymptomatic cerebral infarction and screening for patients with stroke/asymptomatic cerebral infarction. In addition, by utilizing the knowledge of the present invention and inhibiting the pathway for the synthesis of acrolein from polyamine in vivo through polyamine oxidase mediated oxidative deamination, it is possible to prevent stroke/asymptomatic cerebral infarction or inhibiting the progression of the disease. Furthermore, by utilizing the knowledge of the present invention and searching for compounds that inhibit polyamine oxidase, it is possible to obtain therapeutic agents for stroke/asymptomatic cerebral infarction.

<SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The present invention relates to a diagnostic method for stroke/asymptomatic cerebral infarction using polyamine or acrolein content, polyamine oxidase activity or protein content thereof as an indicator. Furthermore, the present invention relates to a screening method for patients with stroke/asymptomatic cerebral infarction using polyamine or acrolein content, polyamine oxidase activity or protein content thereof as an indicator. 2. Description of the Related Art Cerebrovascular disease is the common cause of death next to malignant neoplasm and cardiac disease, and the annual loss of life number thereof is around 10 times of that of renal disease. Moreover, it causes such a tremendous trouble in daily life, for aftereffect of the disease accompanies paralysis and akinesia for example. Stroke constitutes a majority of the cerebrovascular diseases, and early detection and treatment of the disease are difficult. Furthermore, asymptomatic brain infarction that does not show any subjective symptoms is mostly detected accidentally by diagnostic imaging. So, in present circumstances, there have been no diagnostic markers available in blood or urine examination. Therefore, development of a simple and accurate diagnostic method, which does not require expensive medical equipments such as diagnostic imaging system, has been desired. By the way, polyamine is biogenic amine that exists in the body universally, and spermine, spermidine or putrescine is the representatives. And these polyamines exist in high concentration in cells and act as cell growth factors by interacting with nucleic acids within the body. On the other hand, polyamine produces cytotoxic acrolein (CH 2 ═CH—CHO) during its metabolic process. This acrolein is detoxified by aldehyde dehydrogenase in cells, but it shows intense toxicity when it leaks out of cells. In addition, since polyamine accumulates in the plasma of patients with chronic renal failure, it is assumed that polyamine is one of the causative substances of uremia. Moreover, it is said that it is difficult to remove this polyamine by dialyses thoroughly. Thus, clarification the essence of polyamine-induced toxicity leads to the development of more effective therapeutic agents of uremia. Based on this standpoint, the present inventors tried to inhibit polyamine oxidase, which acts in the pathway for the synthesis of acrolein from polyamine, by using amino guanidine. And as a result, it was confirmed that the polyamine lost its toxicity (Japanese Patent Publication No. 2002-281999). In diseases that involve tissue destruction, it is possible with high probability that polyamine liberated from cells receives oxidative deaminated by polyamine oxidase in plasma, then acrolein is formed in large quantities, so that the formed acrolein is associated with toxicity.

<SOH> SUMMARY OF TUE INVENTION <EOH>As described above, it was known that acrolein generated by oxidative degradation of polyamine is involved in uremia in kidney diseases. However, there has not been sufficient knowledge on whether acrolein is involved in other cerebrovascular diseases such as stroke. The term “stroke” represents local neuropsychiatric symptoms that occur acutely during the course of a pathologic process of cerebral blood vessel, and cerebral infarction and intracerebral bleeding are fundamental as causative diseases. Therefore, the problem to be solved by the present invention is to examine whether or not some quantitative change occurs in the polyamine or acrolein content. If acrolein content changes in patients with stroke, then diagnosis of stroke/asymptomatic cerebral infarction using acrolein as an indicator will be enabled. Moreover, since polyamine oxidase in plasma is involved in the process of the synthesis of acrolein from polyamine, examination on whether some change in polyamine oxidase activity and protein content thereof occurs or not is also the problem to be solved by the present invention. The present inventors measured the acrolein content, the polyamine content and the polyamine oxidase activity in plasma of the subjects, and then compared on the difference between stroke/asymptomatic cerebral infarction group and healthy group or group of other brain disease. As a result, this study confirmed that acrolein content and polyamine oxidase activity in plasma were obviously high in the stroke/asymptomatic cerebral infarction group, compared with the healthy group or the group of other brain diseases. Further still, the inventors confirmed that infarction is found in subjects with high acrolein content and polyamine oxidase activity in plasma, by taking head tomographic images of the subjects using magnetic resonance imaging (MRI), and thus the present invention was completed. In other words, the present invention provides a diagnostic method for discovering and predicting stroke/asymptomatic cerebral infarction. According to the present invention, by measuring acrolein content, polyamine oxidase activity or protein content of polyamine oxidase, or polyamine content in plasma, stroke/asymptomatic cerebral infarction can be predicted and discovered. The present invention provides a diagnostic method for stroke/asymptomatic cerebral infarction and a screening method for patients with stroke/asymptomatic cerebral infarction by measuring acrolein content, polyamine content, or polyamine oxidase activity or protein content thereof. The knowledge of the present invention indicates the possibility of preventing stroke/asymptomatic cerebral infarction or inhibiting the progression of the diseases by blocking the pathway for the synthesis of acrolein from polyamine in vivo by way of polyamine oxidase mediated oxidative deamination. The knowledge of the present invention further indicates the possibility of obtaining therapeutic agents for stroke/asymptomatic cerebral infarction by searching for compounds that inhibit polyamine oxidase, therefore various application can be achieved.

20080429

20140506

20081016

70138.0

C12Q126

SHEN, BIN

METHOD OF DIAGNOSING APOPLECTIC STROKE/ASYMPTOMATIC BRAIN INFARCTION USING ACROLEIN CONTENT

UNDISCOUNTED

ACCEPTED

C12Q

ACCEPTED

Pharmaceutical Composition Of Piperazine Derivatives

The present invention relates to a liquid composition containing an active substance belonging to the family of substituted benzhydryl piperazines with reduced amounts of preservatives.

1. A liquid pharmaceutical composition comprising an active substance chosen among cetirizine, levocetirizine and efletirizine, and at least one preservative, wherein the amount of preservative is in the case of parahydroxybenzoate esters more than 0 and less than 1.5 mg/ml of the composition, and in the case of other preservatives is such that it leads to the same preservative effects as a parahydroxybenzoate esters concentration of more than 0 and less than 1.5 mg/ml. 2. A liquid pharmaceutical composition according to claim 1, wherein it is an aqueous composition. 3. A liquid pharmaceutical composition according to claim 1, wherein the preservative is selected from the group of methyl parahydroxybenzoate, ethyl parahydroxybenzoate, propyl parahydroxybenzoate , a mixture of methyl parahydroxybenzoate and ethyl parahydroxybenzoate or propyl parahydroxybenzoate, and a mixture of methyl parahydroxybenzoate and propyl parahydroxybenzoate. 4. A liquid pharmaceutical composition according to claim 3, wherein the preservatives is a mixture of methyl parahydroxybenzoate and propyl parahydroxybenzoate in a ratio of 9/1 expressed in weight. 5. A liquid pharmaceutical composition according to claim 1, wherein the pharmaceutical composition contains an amount of p-hydroxybenzoate esters (methyl p-hydroxybenzoate/propyl p-hydroxybenzoate in a ratio of 9/1 expressed in weight) selected in the range of 0.0001 and 1.4 mg/ml of the composition. 6. A liquid pharmaceutical composition according to claim 1, wherein the pharmaceutical composition contains an amount of thimerosal selected in the range of 0.0001 and 0.05 mg/ml of the composition. 7. A liquid pharmaceutical composition according to claim 1, wherein the pharmaceutical composition contains an amount of chlorhexidine acetate selected in the range of 0.0001 and 0.05 mg/ml of the composition. 8. A liquid pharmaceutical composition according to claim 1, wherein the pharmaceutical composition contains an amount of benzylalcohol selected in the range of 0.0001 and 10 mg/ml of the composition. 9. A liquid pharmaceutical composition according to claim 1, wherein the pharmaceutical composition contains an amount of benzalkonium chloride selected in the range of 0.0001 and 0.05 mg/ml of the composition. 10. A liquid pharmaceutical composition according to claim 1, wherein the active substance is cetirizine. 11. A liquid pharmaceutical composition according to claim 1, wherein the active substance is levocetirizine. 12. A liquid pharmaceutical composition according to claim 1, wherein the composition is in the form of oral solutions, nasal drops, eye drops or ear drops.

The present invention relates to a liquid pharmaceutical composition containing an active substance such as cetirizine, levocetirizine and efletirizine. A number of substances belonging to the family of substituted benzhydryl piperazines are known to be substances with useful pharmacological properties. European Patent EP 58146, filed in the name of UCB, S.A., describes substituted benzhydryl piperazines having the general formula in which L stands for an —OH or —NH2 group, X and X′, taken separately, stand for a hydrogen atom, a halogen atom, a linear or branched alkoxy radical at C1 or C4, or a trifluoromethyl radical, m equals 1 or 2, n equals 1 or 2, as well as their pharmaceutically acceptable salts. Of these compounds, 2-[2-[4-[(4-chlorophenyl)phenylmethyl]-1-piperazinyl]ethoxy]-acetic acid, also known under the name of cetirizine, and its dichlorohydrate are well known for their antihistaminic properties. The active substances belonging to the family of substituted benzhydryl piperazines specifically include 2-[2-[4-[(4-chlorophenyl)phenylmethyl]-1-piperazinyl]ethoxy]-acetic acid (cetirizine), 2-[2-[4-[bis(4-fluorophenyl)methyl]-1-piperazinyl]ethoxy]acetic acid (efletirizine), their optically active isomers when applicable, as well as their pharmaceutically acceptable salts. In the pharmaceutical filed, solutions and drops are generally produced as germ-free compositions during their production processes. However, once the seal of the containers is broken, and the pharmaceutical compositions are completely used over a period of time, these pharmaceutical compositions are continuously exposed to the risk of being contaminated by the microorganisms existing in the environment or the human body, each time the containers are used and their covers are opened or closed. It has now surprisingly been found that the active substances belonging to the family of substituted benzhydryl piperazines possess a preservative effect in aqueous solutions. The purpose of the invention concerns a liquid pharmaceutical composition containing an active substance belonging to the family of substituted benzhydryl piperazines chosen among cetirizine, levocetirizine and efletirizine, and a reduced amount of preservatives. The present invention is based on the unexpected recognition that a pharmaceutical composition comprising an active substance belonging to the family of substituted benzhydryl piperazines and a reduced amount of preservatives is stable during a long period of time. Stability means the capacity to resists to microbial contamination. The present invention encompasses a pharmaceutical composition comprising an active substance belonging to the family of substituted benzhydryl piperazines and an amount of parahydroxybenzoate esters used as preservatives less than 3 mg/ml of the composition, a normal concentration to preserve aqueous solutions. The present invention encompasses a pharmaceutical composition comprising an active substance chosen among cetirizine, levocetirizine and efletirizine and at least one preservative, wherein the amount of preservative is in the case of parahydroxybenzoate esters more than 0 and less than 1.5 mg/ml of the composition, and in the case of other preservatives corresponds to the bactericidal effect of a parahydroxybenzoate esters concentration of more than 0 and less than 1.5 mg/ml. Generally, the pharmaceutical composition of the invention is liquid and preferably aqueous. In the pharmaceutical composition of the invention, the active substance is generally selected from the group of cetirizine, levocetirizine, efletirizine, and their pharmaceutically acceptable salts. Preferably, the active substance is selected from the group of cetirizine, levocetirizine, and their pharmaceutically acceptable salts. The term “cetirizine” refers to the racemate of [2-[4-[(4 chlorophenyl)phenylmethyl]-1-piperazinyl]ethoxy]-acetic acid and its dihydrochloride salt which is well known as cetirizine dihydrochloride; its levorotatory and dextrorotatory enantiomers are known as levocetirizine and dextrocetirizine. Processes for preparing cetirizine, an individual optical isomer thereof or a pharmaceutically acceptable salt thereof have been described in European Patent 0 058 146, Great Britain Patent 2.225.320, Great Britain Patent 2.225.321, U.S. Pat. No. 5,478,941, European Patent application 0 601 028, European Patent Application 0 801 064 and International Patent Application WO 97/37982. The term “levocetirizine” as used herein means the levorotatory enantiomer of cetirizine. More precisely, it means that the active substance comprises at least 90% by weight, preferably at least 95% by weight, of one individual optical isomer of cetirizine and at most 10% by weight, preferably at most 5% by weight, of the other individual optical isomer of cetirizine. Each individual optical isomer may be obtained by conventional means, i.e., resolution from the corresponding racemic mixture or by asymmetric synthesis. Each individual optical isomer may be obtained from its racemic mixture by using conventional means such as disclosed in British patent application No. 2,225,321. Additionally, each individual optical isomer can be prepared from the racemic mixture by enzymatic biocatalytic resolution, such as disclosed in U.S. Pat. Nos. 4,800,162 and 5,057,427. The term “efletirizine” as used herein refers to 2-[2-[4-[bis(4-fluorophenyl)methyl]-1-piperazinyl]ethoxy]acetic acid. Efletirizine is encompassed within general formula I of European patent No. 58146, which relates to substituted benzhydrylpiperazine derivatives. Efletirizine has been found to possess excellent antihistaminic properties. It belongs to the pharmacological class of histamine H1-receptor antagonists and shows in vitro high affinity and selectivity for H1-receptors. It is useful as an antiallergic, and antihistaminic agent. Two pseudopolymorphic crystalline forms of efletirizine dihydrochloride, namely anhydrous efletirizine dihydrochloride and efletirizine dihydrochloride monohydrate, are described in the European patent No. 1 034 171, and another pseudopolymorphic form of efletirizine dihydrochloride is described in the international patent application WO 03/009849. Processes for preparing efletirizine or a pharmaceutically acceptable salt thereof have been described in European Patent 1 034 171, and in the international patent applications WO 97/37982 and WO 03/009849. The term “pharmaceutically acceptable salts” as used herein refers not only to addition salts with pharmaceutically acceptable non-toxic organic and inorganic acids, such as acetic, citric, maleic, succinic, ascorbic, hydrochloric, hydrobromic, sulfuric, and phosphoric acids and the like, but also its metal salts (for example sodium or potassium salts) or ammonium salts, the amine salts and the aminoacid salts. The best results have been obtained with dihydrochloride salts. By preservatives we understand a chemically substance that inhibits the development of microorganisms or, in an ideal instance, kills them; so antimicrobial agent able to limit or avoid the growth of microorganisms such as bacteria, yeast and moulds in a solution. Preservatives will comply with Eur P. and USP requirements: for a product incubated with a large number of bacteria and fungi, the preservative must kill and reduce a required amount of bacteria and fungi within a prescribed time period. Examples of preservatives are p-hydroxybenzoate esters (methyl parahydroxybenzoate, ethyl parahydroxybenzoate, propyl parahydroxybenzoate, butyl parahydroxybenzoate, C1-C20 alkyl parahydroxybenzoate and their sodium salts), acrinol, methyl rosaniline chloride, benzalkonium chloride, benzethonium chloride, cetylpyridinium chloride, cetylpyrodium bromide, chlorohexidine, chlorohexidine acetate, benzylalcohol, alcohol, chlorobutanol, isopropanol, ethanol, thimerosal, phenol, sorbic acid, potassium and calcium sorbate, benzoic acid, potassium and calcium benzoate, sodium benzoate, calcium acetate, calcium disodium ethylenediaminetetraacetate, calcium propionate, calcium sorbate, diethyl pyrocarbonate, sulphur dioxide, sodium sulphite, sodium bisulfite, boric acid, sodium tetraborate, propionic acid, sodium and calcium propionate, sodium thiosulfate, or a mixture therefore. Generally, the preservative is selected from the group of thimerosal, chlorohexidine acetate, benzylalcohol, benzalkonium chloride, p-hydroxybenzoate esters (methyl parahydroxybenzoate, ethyl parahydroxybenzoate, propyl parahydroxybenzoate, butyl parahydroxybenzoate, C1-C20 alkyl parahydroxybenzoate or a mixture thereof. Preferably the preservative is selected from the group of methyl parahydroxybenzoate, ethyl parahydroxybenzoate, propyl parahydroxybenzoate, a mixture of methyl parahydroxybenzoate and ethyl parahydroxybenzoate or propyl parahydroxybenzoate, and a mixture of methyl parahydroxybenzoate and propyl parahydroxybenzoate. Best results have been obtained with a mixture of methyl parahydroxybenzoate and propyl parahydroxybenzoate in a ratio of 9/1 expressed in weight. In a particular embodiment of the invention, the pharmaceutical composition contains an amount of p-hydroxybenzoate esters (methyl p-hydroxybenzoate/propyl p-hydroxybenzoate in a ratio of 9/1 expressed in weight) selected in the range of 0.0001 and 1.5 mg/ml of the composition. Preferably, it contains an amount selected in the range of 0.01 and 1.125 mg/ml. More preferably it contains an amount of preservatives selected in the range of 0.1 and 1 mg/ml. In a particular embodiment of the invention, the pharmaceutical composition contains an amount of thimerosal selected in the range of 0.0001 and 0.05 mg/ml of the composition. Preferably, it contains an amount selected in the range of 0.005 and 0.035 mg/ml. More preferably it contains an amount of preservatives selected in the range of 0.007 and 0.025 mg/ml. In a particular embodiment of the invention, the pharmaceutical composition contains an amount of chlorhexidine acetate selected in the range of 0.0001 and 0.05 mg/ml of the composition. Preferably, it contains an amount selected in the range of 0.005 and 0.035 mg/ml. More preferably it contains an amount of preservatives selected in the range of 0.007 and 0.025 mg/ml. In a particular embodiment of the invention, the pharmaceutical composition contains an amount of benzylalcohol selected in the range of 0.0001 and 10 mg/mi of the composition. Preferably, it contains an amount selected in the range of 0.05 and 7.5 mg/ml. More preferably it contains an amount of preservatives selected in the range of 1 and 5 mg/ml. In a particular embodiment of the invention, the pharmaceutical composition contains an amount of benzalkonium chloride selected in the range of 0.0001 and 0.05 mg/ml of the composition. Preferably, it contains an amount selected in the range of 0.005 and 0.035 mg/ml. More preferably it contains an amount of preservatives selected in the range of 0.01 and 0.025 mg/ml. The amount of the selected preservative is defined by comparison with the amount of parahydroxybenzoate ester leading to the same preservative effect. The optimum amount of preservative used in the invention depends on its nature. The preferred amount of preservative is such that it gives the same preservative effect as an amount of parahydroxybenzoate ester in the range of 0.2 and 1.125 mg/ml of the pharmaceutical composition. By patient, we understand children, adolescents and adults, preferably of 2 years old. The targeted patients are usually old from 2 years and more. A preferred daily dosage provides from about 0.0005 mg to about 2 mg of levocetirizine or a pharmaceutically acceptable salt thereof, per kg of body weight per patient. A particularly preferred daily dosage is from about 0.001 to about 2 mg per kg of body weight per patient. The best results have been obtained with a daily dosage from about 0.005 to 1 mg per kg of body weight per patient. The dosage may be administered once per day of treatment, or divided into smaller dosages, for examples 1 to 4 times a day, and preferably 1 to 3 times a day, and administrated over about a 24 hours time period to reach a total given dosage. Best results have been obtained with an administration of a composition of the invention twice a day for infants; and 5 mg once a day for children and adults. The exact dosages in which the compositions are administrated can vary according to the type of use, the mode of use, the requirements of the patient, as determined by a skilled practitioner. The exact dosage for a patient may be specifically adapted by a skilled person in view of the severity of the condition, the specific formulation used, and other drugs which may be involved. The pharmaceutical forms according to the present invention may be prepared according to conventional methods used by pharmacists. The forms can be administered together with other components or biologicaly active agents, pharmaceutically acceptable surfactants, excipients, carriers, diluents and vehicles. The pharmaceutical compositions of the invention include any conventional therapeutical inert carrier. The pharmaceutical compositions can contain inert as well as pharmacodynamically active additives. Liquid compositions can for example take the form of a sterile solution which is miscible with water. Furthermore, substances conventionally used as preserving, stabilizing, moisture-retaining, and emulsifying agents as well as substances such as salts for varying the osmotic pressure, substances for varying pH such as buffers, and other additives can also be present. If desired an antioxidant can be included in the pharmaceutical compositions. Pharmaceutical acceptable excipients or carriers for compositions include saline, buffered saline, dextrose or water. Compositions may also comprise specific stabilizing agents such as sugars, including mannose and mannitol. Carrier substances and diluents can be organic or inorganic substances, for example water, gelatine, lactose, starch, gum arabic, polyalkylene glycol, cellulose compounds and the like. A prerequisite is that all adjuvants and substances used in the manufacture of the pharmaceutical compositions are nontoxic. Pharmaceutical compositions can be administered by spray inhalation. Any conventional pharmaceutical composition for spray inhalation administration may be used. Another preferred mode of administration is by aerosol. The pharmaceutical compositions according to the present invention may also be administered orally. They may also be administered by nasal instillation, aerosols. The pharmaceutical compositions which can be used for oral administration is liquid, for example, in the form of solutions, syrups, drops and the like. The pharmaceutical forms, such as drops, nasal drops, eye drops and ear drops are prepared by conventional pharmaceutical methods. The compounds of the present invention are mixed with a solid or liquid, non-toxic and pharmaceutically acceptable carrier and possibly also mixed with a dispersing agent, a stabilizing agent and the like. If appropriate, it is also possible to add sweeteners, coloring agents and the like. Preferably, the pharmaceutical composition of the invention is administered in traditional form for oral administration, as oral liquid preparation such as syrup. Best results have been obtained with an oral dosage form, in particular liquid formulations such as syrup for children. An advantage of the invention is that reducing the concentration of the preservative leads to a reduction of the risk of an allergic reaction in sensitive patients. Another advantage of the invention is the ability to make easier the manufacturing process avoiding the solubilization of important amounts of preservatives not freely soluble in water. The invention is further defined by reference to the following examples. EXAMPLE 1 Preservative Effect of Cetirizine An oral solution and drops containing cetirizine are prepared. The compositions are given in table 1. TABLE 1 Cetirizine compositions Oral solution Drops Cetirizine hydrochloride (mg) 1 10 Sorbitol sol. At 70% (mg) 450 — Glycerine (mg) 200 250 Propyleneglycol (mg) 50 350 Sodium saccharinate (mg) 1 10 Banana flavour (mg) 0.1754 — Sodium acetate (mg) 4.2 10 Acetic acid ad pH 5 ad pH 5 Purified water (ml) ad 1 ad 1 The antimicrobial preservative effectiveness tests are realized according to the European Pharmacopoeia (Chap. 5.1.3.). Samples of the oral solution and the drops are inoculated with bacterial and yeast suspensions of Pseudomonas aeruginosa ATCC 9027, Escherichia Coli ATCC 8739, Staphylococcus aureus ATC C6538, Candida albicans ATCC10231 and Aspergillus niger ATCC16404. The number of viable microorganisms per ml of preparations under test are determined. The results are given in tables 2 and 3. TABLE 2 Microbial content in inoculated sample of the oral solution Time Pseudomonas Escherichia Staphylococcus Candida Aspergillus (days) aeruginosa coli aureus albicans niger Inoculum 5.5 × 105 4.6 × 105 4.0 × 105 3.7 × 105 2.3 × 106 0 4.9 × 105 4.7 × 105 3.1 × 105 2.6 × 105 1.7 × 106 7 <100 <100 <100 <100 4.8 × 105 14 <1 <1 <1 2 8.2 × 103 21 <1 <1 <1 <1 5.5 × 103 28 <1 <1 <1 <1 5.0 × 103 TABLE 3 Microbial content in inoculated sample of the drops Time Pseudomonas Escherichia Staphylococcus Candida Aspergillus (days) aeruginosa coli aureus albicans niger Inoculum 4.0 × 105 3.4 × 105 3.6 × 105 3.5 × 105 1.8 × 106 0 3.5 × 105 3.8 × 105 2.2 × 105 2.6 × 105 1.6 × 106 7 <100 <100 <100 <100 <104 14 <1 <1 <1 <1 <100 21 <1 <1 <1 <1 <1 28 <1 <1 <1 <1 <1 In both cases, a rapid disappearance of Pseudomonas aeruginosa, Escherichia Coli, Staphylococcus aureus and Candida albicans is observed in the inoculated samples. For Aspergillus niger, the number of viable spores is significantly reduced in the oral solution while a rapid disappearance is observed in the drops. EXAMPLE 2 Preservative Effect of Levocetirizine An oral solution and drops containing levocetirizine are prepared. The compositions are given in table 4. TABLE 4 Levocetirizine compositions Oral solution Drops Levocetirizine hydrochloride (mg) 0.5 5 Maltitol-Lycasin 80-55 (mg) 400 — Glycerine 85%(mg) 235.2 294.1 Propyleneglycol (mg) — 350 Sodium saccharinate (mg) 0.5 10 Tutti frutti flavour (mg) 0.15 — Sodium acetate (mg) 3.4 5.7 Acetic acid (mg) 0.5 0.53 Purified water (ml) ad 1 ad 1 The antimicrobial preservative effectiveness tests are realized according to the European Pharmacopoeia (Chap. 5.1.3.). Samples of the oral solution and the drops are inoculated with bacterial and yeast suspensions of Pseudomonas aeruginosa ATCC 9027, Escherichia Coli ATCC 8739, Staphylococcus aureus ATC C6538, Candida albicans ATCC10231 and Aspergillus niger ATCC16404. The number of viable microorganisms per ml of preparations under test is determined. The results are given in tables 5 and 6. TABLE 5 Microbial content in inoculated sample of the oral solution Time Pseudomonas Escherichia Staphylococcus Candida Aspergillus (days) aeruginosa coli aureus albicans niger Inoculum 3.6 × 105 1.7 × 105 2.7 × 105 3.4 × 105 1.7 × 106 0 3.2 × 105 1.8 × 105 3.5 × 105 3.9 × 105 1.6 × 106 7 150 <100 <100 2.8 × 104 1.0 × 106 14 <1 <1 <1 1.4 × 104 4.8 × 105 21 <1 <1 <1 2.6 × 102 2.2 × 105 28 <1 <1 <1 6.2 × 103 5.3 × 105 TABLE 6 Microbial content in inoculated sample of the drops Time Pseudomonas Escherichia Staphylococcus Candida Aspergillus (days) aeruginosa coli aureus albicans niger Inoculum 3.6 × 105 1.7 × 105 2.7 × 105 3.4 × 105 1.7 × 106 0 3.2 × 105 1.5 × 105 3.1 × 105 1.8 × 105 1.7 × 106 7 <100 <100 <100 <100 9.0 × 104 14 <1 <1 <1 <1 <1000 21 <1 <1 <1 <1 <1 28 <1 <1 <1 <1 <1 In both cases, a rapid disappearance of Pseudomonas aeruginosa, Escherichia Coli, Staphylococcus aureus is observed in the inoculated samples. A disappearance of Candida albicans and Aspergillus niger is also observed in the drops. EXAMPLE 3 Efficacy of Antimicrobial Preservation of Cetirizine Aqueous Solutions by p-hydroxbenzoate Esters. Oral solutions and drops containing cetirizine according to example 1 but also containing mixtures of p-hydroxybenzoate esters (methyl p-hydroxybenzoate/propyl p-hydroxybenzoate in a ratio of 9/1 expressed in weight) are prepared. The total amounts of p-hydroxybenzoate esters are 0. 15 mg/ml, 0.45 mg/ml, 0.75 mg/ml and 1.05 mg/ml. The efficacy of antimicrobial preservation of these solutions and drops is determined according to the European Pharmacopoeia (Chap. 5.1.3.). The results of the tests are given in tables 7 to 14. TABLE 7 Microbial content in inoculated sample of the oral solution containing 0.15 mg/ml of p-hydroxybenzoate esters Time Pseudomonas Escherichia Staphylococcus Candida Aspergillus (days) aeruginosa coli aureus albicans niger Inoculum 5.5 × 105 4.6 × 105 4.0 × 105 3.7 × 105 2.3 × 106 0 5.1 × 105 4.5 × 105 3.0 × 105 4.0 × 105 4.1 × 106 14 <1 <1 <1 <1 9.1 × 103 28 <1 <1 <1 <1 750 TABLE 8 Microbial content in inoculated sample of the oral solution containing 0.45 mg/ml of p-hydroxybenzoate esters Time Pseudomonas Escherichia Staphylococcus Candida Aspergillus (days) aeruginosa coli aureus albicans niger Inoculum 5.5 × 105 4.6 × 105 4.0 × 105 3.7 × 105 2.3 × 106 0 5.2 × 105 4.9 × 105 3.3 × 105 2.9 × 105 1.2 × 106 14 <1 <1 <1 <1 <100 28 <1 <1 <1 <1 2 TABLE 9 Microbial content in inoculated sample of the oral solution containing 0.75 mg/ml of p-hydroxybenzoate esters Time Pseudomonas Escherichia Staphylococcus Candida Aspergillus (days) aeruginosa coli aureus albicans niger Inoculum 5.5 × 105 4.6 × 105 4.0 × 105 3.7 × 105 2.3 × 106 0 3.9 × 105 4.4 × 105 4.0 × 105 1.9 × 105 1.9 × 106 14 <1 <1 <1 <1 <100 28 <1 <1 <1 <1 <1 TABLE 10 Microbial content in inoculated sample of the oral solution containing 1.05 mg/ml of p-hydroxybenzoate esters Time Pseudomonas Escherichia Staphylococcus Candida Aspergillus (days) aeruginosa coli aureus albicans niger Inoculum 5.5 × 105 4.6 × 105 4.0 × 105 3.7 × 105 2.3 × 106 0 3.3 × 105 4.1 × 105 3.1 × 105 1.4 × 105 1.2 × 106 14 <1 <1 <1 <1 <100 28 <1 <1 <1 <1 <1 TABLE 11 Microbial content in inoculated sample of the drops containing 0.15 mg/ml of p-hydroxybenzoate esters Time Pseudomonas Escherichia Staphylococcus Candida Aspergillus (days) aeruginosa coli aureus albicans niger Inoculum 4.0 × 105 3.4 × 105 3.6 × 105 3.5 × 105 1.8 × 106 0 4.3 × 105 4.0 × 105 2.0 × 105 2.5 × 105 1.5 × 106 14 <1 <1 <1 <1 <100 28 <1 <1 <1 <1 <1 TABLE 12 Microbial content in inoculated sample of the drops containing 0.45 mg/ml of p-hydroxybenzoate esters Time Pseudomonas Escherichia Staphylococcus Candida Aspergillus (days) aeruginosa coli aureus albicans niger Inoculum 4.0 × 105 3.4 × 105 3.6 × 105 3.5 × 105 1.8 × 106 0 3.6 × 105 3.6 × 105 1.7 × 105 2.1 × 105 1.4 × 106 14 <1 <1 <1 <1 <100 28 <1 <1 <1 <1 <1 TABLE 13 Microbial content in inoculated sample of the drops containing 0.75 mg/ml of p-hydroxybenzoate esters Time Pseudomonas Escherichia Staphylococcus Candida Aspergillus (days) aeruginosa coli aureus albicans niger Inoculum 4.0 × 105 3.4 × 105 3.6 × 105 3.5 × 105 1.8 × 106 0 4.1 × 105 3.6 × 105 2.6 × 105 2.5 × 105 1.6 × 106 14 <1 <1 <1 <1 <100 28 <1 <1 <1 <1 <1 TABLE 14 Microbial content in inoculated sample of the drops containing 1.05 mg/ml of p-hydroxybenzoate esters Time Pseudomonas Escherichia Staphylococcus Candida Aspergillus (days) aeruginosa coli aureus albicans niger Inoculum 4.0 × 105 3.4 × 105 3.6 × 105 3.5 × 105 1.8 × 106 0 3.9 × 105 3.7 × 105 2.8 × 105 2.2 × 105 1.3 × 106 14 <1 <1 <1 <1 <100 28 <1 <1 <1 <1 <1 In all cases, the disappearance of Pseudomonas aeruginosa, Escherichia Coli, Staphylococcus aureus and Candida albicans is observed in the inoculated samples. For Aspergillus niger, the number of viable spores is significantly reduced in the oral solution while a rapid disappearance is observed in the drops. In all cases the recommended efficacy criteria are achieved. EXAMPLE 4 Efficacy of Antimicrobial Preservation of Levocetirizine Aqueous Solutions by p-hydroxybenzoate Esters Oral solutions and drops containing levocetirizine according to example 2 but also containing mixtures of p-hydroxybenzoate esters (methyl p-hydroxybenzoate/propyl p-hydroxybenzoate in a ratio of 9/1 expressed in weight) are prepared. The total amounts of p-hydroxybenzoate esters are 0.375 mg/ml, 0.75 mg/ml and 1.125 mg/ml. The efficacy of antimicrobial preservation of these solutions and drops is determined according to the European Pharmacopoeia (Chap. 5.1.3.). The results of the tests are given in tables 15 to 20. TABLE 15 Microbial content in inoculated sample of the oral solution containing 0.375 mg/ml of p-hydroxybenzoate esters Time Pseudomonas Escherichia Staphylococcus Candida Aspergillus (days) aeruginosa coli aureus albicans niger Inoculum 3.6 × 105 1.7 × 105 2.7 × 105 3.4 × 105 1.7 × 106 0 3.7 × 105 1.3 × 105 2.8 × 105 3.8 × 105 1.6 × 106 14 <1 <1 <1 1.7 × 104 1.6 × 105 28 <1 <1 <1 <1 <100 TABLE 16 Microbial content in inoculated sample of the oral solution containing 0.75 mg/ml of p-hydroxybenzoate esters Time Pseudomonas Escherichia Staphylococcus Candida Aspergillus (days) aeruginosa coli aureus albicans niger Inoculum 3.6 × 105 1.7 × 105 2.7 × 105 3.4 × 105 1.7 × 106 0 3.5 × 105 1.6 × 105 2.4 × 105 3.4 × 105 1.6 × 106 14 <1 <1 <1 5.5 × 102 1.4 × 104 28 <1 <1 <1 <1 <1 TABLE 17 Microbial content in inoculated sample of the oral solution containing 1.125 mg/ml of p-hydroxybenzoate esters Time Pseudomonas Escherichia Staphylococcus Candida Aspergillus (days) aeruginosa coli aureus albicans niger Inoculum 3.6 × 105 1.7 × 105 2.7 × 105 3.4 × 105 1.7 × 106 0 3.9 × 105 1.2 × 105 3.0 × 105 3.5 × 105 1.4 × 106 14 <1 <1 <1 <10 <1000 28 <1 <1 <1 <1 <1 TABLE 18 Microbial content in inoculated sample of the drops containing 0.375 mg/ml of p-hydroxybenzoate esters Time Pseudomonas Escherichia Staphylococcus Candida Aspergillus (days) aeruginosa coli aureus albicans niger Inoculum 3.6 × 105 1.7 × 105 2.7 × 105 3.4 × 105 1.7 × 106 0 3.1 × 105 1.2 × 105 2.6 × 105 1.7 × 105 1.8 × 106 14 <1 <1 <1 <1 <1000 28 <1 <1 <1 <1 <1 TABLE 19 Microbial content in inoculated sample of the drops containing 0.75 mg/ml of p-hydroxybenzoate esters Time Pseudomonas Escherichia Staphylococcus Candida Aspergillus (days) aeruginosa coli aureus albicans niger Inoculum 3.6 × 105 1.7 × 105 2.7 × 105 3.4 × 105 1.7 × 106 0 3.1 × 105 1.0 × 105 3.0 × 105 1.8 × 105 1.4 × 106 14 <1 <1 <1 <1 <1000 28 <1 <1 <1 <1 <1 TABLE 20 Microbial content in inoculated sample of the drops containing 1.125 mg/ml of p-hydroxybenzoate esters Time Pseudomonas Escherichia Staphylococcus Candida Aspergillus (days) aeruginosa coli aureus albicans niger Inoculum 3.6 × 105 1.7 × 105 2.7 × 105 3.4 × 105 1.7 × 106 0 2.9 × 105 6.9 × 104 2.7 × 105 5.0 × 104 1.5 × 106 14 <1 <1 <1 <1 <1000 28 <1 <1 <1 <1 <1 In all cases, the disappearance of Pseudomonas aeruginosa, Escherichia Coli, Staphylococcus aureus and Candida albicans is observed in the inoculated samples. For Aspergillus niger, the number of viable spores is significantly reduced in the oral solution while a rapid disappearance is observed in the drops. In all cases the recommended efficacy criteria are achieved. EXAMPLE 5 Nasal Solution Containing Cetirizine and Benzalkonium Chloride A solution containing cetirizine is prepared. The composition is given in table 21. TABLE 21 Cetirizine composition Nasal solution Cetirizine hydrochloride (mg) 10 Monobasic sodium phosphate (mg) 10.6 Dibasic sodium phosphate (mg) 29 Benzalkonium chloride (mg) 0.025 Purified water (ml) ad 1 The efficacy of antimicrobial preservation of this solution is determined according to the European Pharmacopoeia (Chap. 5.1.3.). The recommended efficacy criteria are achieved. EXAMPLE 6 Nasal Solution Containing Efletirizine and p-hydroxybenzoate Esters A solution containing efletirizine is prepared. The composition is given in table 22. TABLE 22 Efletirizine composition Nasal solution Efletirizine hydrochloride (mg) 6 Hydroxypropylmethylcellulose (mg) 5 Monobasic sodium phosphate (mg) 8.1 Dibasic sodium phosphate (mg) 6.3 Edeteate disodium (mg) 0.5 Sodium chloride (mg) 1.93 Sodium hydroxide ad pH 6.5 p-hydroxybenzoate esters (mg) 0.375 Purified water (ml) ad 1 The efficacy of antimicrobial preservation of this solution is determined according to the European Pharmacopoeia (Chap. 5.1.3.). The recommended efficacy criteria are achieved. EXAMPLE 7 Oral Solutions and Drops Containing Levocetirizine and Benzylalcohol An oral solution and drops containing levocetirizine are prepared. The compositions are given in table 23. TABLE 23 Levocetirizine compositions Oral solution Drops Levocetirizine hydrochloride (mg) 0.5 5 Maltitol-Lycasin 80-55 (mg) 400 — Glycerine 85%(mg) 235.2 294.1 Propyleneglycol (mg) — 350 Sodium saccharinate (mg) 0.5 10 Tutti frutti flavour (mg) 0.15 — Sodium acetate (mg) 3.4 5.7 Acetic acid (mg) 0.5 0.53 Benzylalcohol (mg) 5.0 5.0 Purified water (ml) ad 1 ad 1 The antimicrobial preservative effectiveness tests are realized according to the European Pharmacopoeia (Chap. 5.1.3.). In all cases the recommended efficacy criteria are achieved. EXAMPLE 8 Oral Solutions and Drops Containing Efletirizine An oral solution and drops containing efletirizine are prepared. The compositions are given in table 24. TABLE 24 Efletirizine compositions Oral solution Drops Efletirizine hydrochloride (mg) 1 10 Maltitol-Lycasin 80-55 (mg) 400 — Glycerine 85%(mg) 235.2 294.1 Propyleneglycol (mg) — 350 Sodium saccharinate (mg) 0.5 10 Tutti frutti flavour (mg) 0.15 — Sodium acetate (mg) 4.2 10 Acetic acid (mg) ad pH 5 ad pH 5 p-hydroxybenzoate esters (mg) 0.375 0.375 Purified water (ml) ad 1 ad 1 The antimicrobial preservative effectiveness tests are realized according to the European Pharmacopoeia (Chap. 5.1.3.). In all cases the recommended efficacy criteria are achieved. EXAMPLE 9 Eve Drops Containing Efletirizine and Thimerosal, Chlorhexidine Acetate and p-hydroxybenzoate Esters Three formulations of eye drops containing efletirizine are prepared. The compositions are given in table 25. TABLE 25 Efletirizine compositions Eye drops Efletirizine hydrochloride (mg) 10 10 10 Boric acid (mg) 20 20 20 Sodium hydroxide ad pH 7 ad pH 7 ad pH 7 Thimerosal (mg) 0.05 — — Chlorhexidine acetate (mg) — 0.05 — p-hydroxybenzoate esters (mg) — — 0.375 Purified water (ml) ad 1 ad 1 ad 1 The antimicrobial preservative effectiveness tests are realized according to the European Pharmacopoeia (Chap. 5.1.3.). In all cases the recommended efficacy criteria are achieved.

20070718

20140121

20071129

83389.0

A61K314965

RODRIGUEZ, RAYNA B

Pharmaceutical Composition Of Piperazine Derivatives

UNDISCOUNTED

ACCEPTED

A61K

ACCEPTED

METHODS FOR THE PREPARATION OF (3R,3aS,6aR) HEXAHYDRO-FURO[2,3-b]FURAN-3-OL

The present invention relates to methods for the preparation of diastereomerically pure (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol as well as a novel intermediate, (3aR,4S,6aS)4-methoxy-tetrahydro-furo[3,4-b]furan-2-one for use in said methods. More in particular the invention relates to a stereoselective method for the preparation of diastereomerically pure (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol, as well as methods for the crystallization of (3aR,4S,6aS)4-methoxy-tetrahydro-furo[3,4-b]furan-2-one and for the epimerization of (3aR,4R,6aS)4-methoxy-tetrahydro-furo[3,4-b]-furan-2-one to (3aR,4S,6aS)4-methoxy-tetrahydro-furo[3,4-b]furan-2-one.

1. A method for the synthesis of (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol having the structure of formula (6), which method comprises the use of intermediates of formula (4). 2. A method for the synthesis of (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol having the structure of formula (6), which method comprises the use of intermediate of formula α-(4). 3. A method according to claim 1 which method comprises the steps of: a) treating compound of formula (3) with a base and subsequently with an acid in the presence of methanol; wherein P1 and P2 are each independently a hydrogen, a hydroxy-protecting group or may together form a vicinal-diol protecting group, R1 is alkyl, aryl or aralkyl; resulting in intermediates of formula (4); and b) reducing intermediates of formula (4) with a reducing agent and applying an intramolecular cyclization reaction to obtain compound of formula (6). 4. A method according to claim 1 which method further comprises crystallizing intermediate of formula α-(4) with a solvent prior to the reduction thereof. 5. A method according to claim 1 which method further comprises a) epimerizing with acid intermediate of formula β-(4) into the intermediate of formula α-(4); and b) crystallizing intermediate of formula α-(4) with a solvent prior to the reduction thereof. 6. A method according to claim 4 which method further comprises after crystallizing intermediate of formula α-(4), a) epimerizing with acid intermediate of formula β-(4) in the mother liquor of said crystallization into the intermediate of formula α-(4); and b) crystallizing intermediate of formula α-(4) with a solvent; prior to the reduction thereof. 7. A method according to claim 5 wherein the epimerization of compound of formula β-(4) to compound of formula α-(4) and crystallization of compound of formula α-(4) occur simultaneously. 8. A method according to claim 7, wherein the simultaneous epimerization of compound of formula β-(4) to compound of formula α-(4) and the crystallization of compound of formula α-(4) is performed in methanol in the presence of an acid by evaporation or partial evaporation of the methanol. 9. A method according to claim 1 which method comprises the steps of: a) treating compound of formula (3) with a base and subsequently with an acid in the presence of a non-methanolic solvent; and subsequently reacting with methanol under acidic conditions; wherein P1 and P2 are each independently a hydrogen, a hydroxy-protecting group or may together form a vicinal-diol protecting group, R1 is alkyl, aryl or aralkyl; resulting in intermediates of formula (4); and b) reducing intermediate of formula (4) with a reducing agent and applying an intramolecular cyclization reaction to obtain compound of formula (6). 10. A method according to claim 3 wherein compounds of formula (3) are obtained by reacting compounds of formula (2) with nitromethane and a base. 11. A method according to claim 10 wherein compounds of formula (2) are obtained by condensing an intermediate of formula (1) or its hydrate, hemihydrate or a mixture thereof with phosphonates of the formula (R60)2P(═O)—CH2—C(═O)OR1, wherein P1 and P2 are as defined in claim 2, R1 is as defined in claim 2, R6 is alkyl, aryl or aralkyl, 12. A method according to claim 3 wherein P1 and P2 together form a dialkyl methylene radical. 13. A method according to claim 10 wherein the base employed for the conversion of compounds of formula (2) into compounds of formula (3) is DBU or TMG or derivatives thereof. 14. A method according to claim 11 wherein the phosphonate of the formula (R60)2P(═O)—CH2—C(═O)OR1 is triethyl phosphonoacetate (TEPA). 15. A method according to claim 3 wherein the conversion of compounds of formula (3) into compounds of formula (4) is performed with a base selected from the group of sodium methoxide, lithium methoxide, DBU or TMG or mixtures thereof. 16. A method according to claim 10, wherein the conversion of compounds of formula (2) into compounds of formula (4) is performed by using DBU or TMG as the base in the conversion of compounds of formula (2) to compounds of formula (3), not isolating compounds of formula (3) and using sodium or lithium methoxide as additional base in the conversion of compounds of formula (3) to compounds of formula (4). 17. A method according to claim 3 wherein the acid employed in the conversion of compounds of formula (3) into compounds of formula (4) is concentrated sulphuric acid in an amount of 2.5 to 5 equivalents based on compound of formula (2) as a 20 to 80 wt % solution in methanol. 18. A method according to claim 4 wherein crystallization of compound of formula α-(4) is performed in an alcohol. 19. A method according to claim 18 wherein the alcohol is isopropanol, t-amyl alcohol or t-butanol. 20. A method for the conversion of compound of formula β-(4) into the compound of formula α-(4) which comprises an epimerization with acid. 21. A method according to claim 5 wherein epimerization of compound of formula β-(4) into compound of formula α-(4) is performed with 0.05 to 1.5 equivalents of MeSO3H in methanol. 22. A method according to claim 5 and 20 to 21 wherein the epimerization is performed at a temperature between 40° C. and reflux temperature. 23. An intermediate having the formula α-(4): 24. An intermediate having the formula β-(4): 25. The intermediate with formula α-(4) of claim 23 in crystalline form. 26. An intermediate having the formula (5) 27. (canceled)

The present invention relates to methods for the preparation of (3R,3aS,6aR) hexahydro-furo[2,3-b]furan-3-ol as well as a novel intermediate, (3aR,4S,6aS)4-methoxy-tetrahydro-furo[3,4-b]furan-2-one for use in said methods. More in particular the invention relates to a stereoselective method for the preparation of (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol, and to a method amenable to industrial scaling up. Hexahydro-furo[2,3-b]furan-3-ol is an important pharmacological moiety present in the structure of retroviral protease inhibitors such as those described by Ghosh et al. in J. Med. Chem. 1996, 39(17), 3278-3290, EP 0 715 618, WO 99/67417, and WO 99/65870. Said publications are hereby incorporated by reference. Several methods for the preparation of hexahydro-furo[2,3-b]furan-3-ol are known. Ghosh et al. in J. Med. Chem. 1996, 39(17), 3278-3290, describe an enantioselective synthesis to obtain both (3R,3aS,6aR) and (3S,3aR,6aS)hexahydro-furo[2,3-b]furan-3-ol in optically pure form starting from 3(R)-diethyl malate and 3(S)-diethyl malate, respectively. Ghosh et al. also disclose the synthesis of a racemic mixture of the (3R,3aS,6aR) and (3S,3aR,6aS) enantiomers of hexahydro-furo[2,3-]furan-3-ol, starting from 2,3-dihydrofuran, followed by an enzymatic resolution of the final product. Pezeck et al. in Tetrahedron Lett. 1986, 27, 3715-3718, also describe a route for the synthesis of hexahydro-furo[2,3-b]-furan-3-ol using ozonolysis. Hexahydro-furo[2,3-b]furan-3-ol is also described as an intermediate in the synthesis of optically active perhydrofuro[2,3-b]furan derivatives in the publication by Uchiyama et al., in Tetrahedron Lett. 2001, 42, 4653-4656. WO 03/022853 relates an alternative method which involves the synthesis of (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol which method starts from a 2,3-diprotected-2,3-dihydroxy-propionaldehyde, which is transformed into a derivative encompassing a nitromethyl and one or two carboxylate moieties. Said derivative is subsequently transformed by a Nef reaction into a tetrahydrofuran compound, which is reduced and submitted to a intramolecular cyclization reaction to obtain the (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol. In order to transform the starting material, i.e. 2,3-diprotected-2,3-dihydroxy-propionaldehyde, into a derivative encompassing one or two carboxylate moieties, WO03/022853 describes different routes, which include a Wittig reaction using phosphorous ylides; a Horner-Emmons reaction using phosphonates in the presence of a base; a Knoevenagel type of condensation reaction using malonate derivatives; or alternatively applying Reformatsky reagents, i.e. precursors of —C(═O)—O— moieties such as cyanide. In particular, the examples disclosed therein, focus on two routes: the Knoevenagel and the Wittig routes. The Knoevenagel route as illustrated in WO03/022853, consists of the addition of dimethyl malonate to a dry solution of the starting material 2,3-O-isopropylidene-glyceraldehyde to produce 2-(2,2-dimethyl-[1,3]dioxolan-4-ylmethylene)-malonic acid dimethyl ester with 2 carboxylates incorporated. Since the starting material is produced in aqueous solution, a laborious isolation procedure encompassing an extraction with tetrahydrofuran and water removal needs to be applied. This extraction and water removal require large amounts of tetrahydrofuran and production time. Further, the yield of the Knoevenagel reaction of 2,3-O-isopropylidene-glyceraldehyde to 2-(2,2-dimethyl-[1,3]dioxolan-4-ylbnethylene)-malonic acid dimethyl ester exhibits a ceiling value of approximately 77% since intrinsically inevitable side reactions occur, even after optimization of conditions. Due to the fact that the obtained di-carboxylated intermediate is a viscous oil, i.e. 2-(2,2-dimethyl-[1,3]dioxolan-4-ylmethylene)-malonic acid dimethyl ester, it needs to be introduced into the subsequent Michael addition as a solution in methanol. Methanol distillation after quench into aqueous NaHCO3 solution, after the acidic Nef and cyclization reactions, but before extraction with an organic solvent such as ethyl acetate has disadvantages. Since the intermediate resulting from the acidic Nef and cyclization reactions, i.e. 4-methoxy-2-oxo-hexahydro-furo[3,4-b]furan-3-carboxylic acid methyl ester, is a labile compound in water, and the methanol distillation requires relatively high temperatures (up to 30° C. to 40° C.), decomposition of the intermediate occurs to polar compounds. These polar compounds remain in the aqueous phase and are further lost because they are not extracted to the organic phase. Since the methanol can not be removed prior to the extractions, a considerable volume is required in the work-up of 4-methoxy-2-oxo-hexahydro-furo[3,4-b]furan-3-carboxylic acid methyl ester. During decarboxylation of 4-methoxy-2-oxo-hexahydro-furo[3,4-b]furan-3-carboxylic acid methyl ester there is significant by-product formation, i.e. (4-hydroxy-2-methoxy-tetrahydro-furan-3-yl)-acetic acid. Furthermore, crystallization of 4-methoxy-tetrahydro-furo[3,4-b]furan-2-one results in a brown solid due to concomitant polymerizations. In addition, for the purification of 4-methoxy-tetrahydro-furo[3,4-b]furan-2-one, at least two acid-base extractive cascades are needed to remove the acid for the cyclization, thus resulting in an overall yield of 4-methoxy-tetrahydro-furo[3,4-b]furan-2-one of 52% based on 4-methoxy-2-oxo-hexahydro-furo [3,4-b]furan-3-carboxylic acid methyl ester, which is considered sub-optimal. All the factors mentioned above disencourage the use of the Knoevenagel route. In fact, the decarboxylation step in this route presents an intrinsic disadvantage when compared to the Wittig route in that such decarboxylation step is not required with the latter. WO03/022853 in Example I provides a Wittig route which employs triethyl phosphono acetate (TEPA) to obtain 3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethyl ester. The subsequent Michael addition to 3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethyl ester, presents limitations in that it produces a nitromethane adduct, i.e. 3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-4-nitro-butyric acid ethyl ester, with a syn:anti ratio of approximately 8:2. Subsequent reduction followed by Nef/cyclization reactions yields the (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol seriously contaminated with its exo-diastereoisomer, i.e. (3R,3aR,6aS)hexahydro-furo[2,3-b]furan-3-ol, with a ratio endo:exo of around 8:2. Although this process does not possess several of the disadvantages attached to the Knoevenagel process, it does not produce pure endo-diastereoisomer since there is no purification step available, such as crystallization, to remove the undesired exo-diastereoisomers that have bees formed during the Michael addition in the anti configuration. In the alternative Wittig route as disclosed in Example II of WO03/022853, the Michael addition product exhibits the same disadvantageous syn:anti ratio (8:2) as in Example I. The ethoxy intermediates (3aR,4S,6aS)4-ethoxy-tetrahydro-furo[3,4-b]-furan-2-one and (3aR,4R,6aS)4-ethoxy-tetrahydro-furo[3,4-b]furan-2-one obtained from the Nef/cyclization reaction were present in a (3aR,4S,6aS)/(3aR,4R,6aS) ratio of approximately 2.5/1, together with a significant amount of anti-isomers, i.e. with the syn:anti ratio of approximately 8:2. Purification of intermediates (3aR,4S,6aS)4-ethoxy-tetrahydro-furo[3,4-b]furan-2-one and (3aR,4R,6aS)4-ethoxy-tetrahydro-furo[3,4-b]furan-2-one by removal of the undesired anti-diastereoisomers by crystallization appears to be impossible to date. Reduction of the mixture and cyclization yielded (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol, seriously contaminated with its exo-diastereoisomer, i.e. (3R,3aR,6aS)hexahydro-furo[2,3-b]-furan-3-ol, with an endo:exo ratio of approximately 8:2. Like the Wittig process of Example I above, this process does not posses several of the disadvantages attached to the Knoevenagel process, but in its present form does not yet provide pure (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol in high industrial yields. Furthermore, the reactor volumes employed for the art-known procedures are large and the number of operations too high, said factors working in detriment of a cost-efficient process, and making thus processes not optimal for industrial scale. There is thus a need for optimized processes for the industrial preparation of diastereomerically pure (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol. It has been surprisingly found that when a Wittig route is employed and the isomers of intermediate of formula (4) and (4′) of WO03/022853 are produced in the methyl acetal form (i.e. R′″ is methyl, and R″ is hydrogen), the yield of crude intermediate of formula (4) based on intermediate of formula (2) is much higher when compared to for instance the ethoxy- or isopropoxy-acetals (where R′″ is ethyl or isopropyl, respectively and R″ is hydrogen). Moreover, it has been surprisingly found that this methyl acetal form of intermediate of formula (4) in the isomeric form (3aR,4S,6aS), can be crystallized from the mixture of the (3aR,4S,6aS) and (3aR,4R,6aS)-isomers of compound of formula (4) and the relatively large amount of isomers (4′). The increased yield and the possibility of crystallization of the isomeric form (3aR,4S,6aS) allows the production of (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol in diastereomerically pure form and enhanced yield. The compound of formula (4), (3aR,4S,6aS)4-methoxy-tetrahydro-furo[3,4-b]furan-2-one, will be referred hereinunder as compound of formula α-(4) or alpha epimer or α-isomer. Likewise, (3aR,4R,6aS)4-methoxy-tetrahydro-furo[3,4-b]furan-2-one will be referred hereinunder as compound of formula β-(4), or beta epimer or β-isomer. It is not only surprising that the methoxy acetal of formula α-(4) can be crystallized, but even more surprising that this crystallization is successful in spite of the low alpha/beta ratio of less than 4/1 of the crude intermediates of formula (4) entering the crystallization. It should be realized that in the Knoevenagel process an alpha/beta ratio of at least 6:1 was required to have a crystallizable intermediate of formula α-(4). Thus, the present invention provides an improved Wittig process and the use of the 4-alpha isomer of 4-methoxy-tetrahydro-furo[3,4-b]furan-2-one, in particular (3aR,4S,6aS), which significantly contributes into an amenable industrial preparation of (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol in diastereomerically pure form. Furthermore, it has been surprisingly found that a mixture in any ratio of the alpha and beta epimers of formula (4) can be transformed into a mixture of predominantly the alpha epimer, which can subsequently be isolated in pure form by crystallization. As such, the present invention provides a novel alkoxy-acetal epimerization of compound of formula (4) which significantly contributes into a cost-effective process for the preparation of (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol. In addition, it has also been surprisingly found that a mixture in almost any ratio of the alpha and beta epimers of formula (4) can be transformed in one single step into the crystalline alpha epimer by simultaneous crystallization and epimerization, also known as crystallization-induced asymmetric transformation. As such the present invention provides furthermore a simultaneous crystallization and epimerization for the isolation of pure (3aR,4S,6aS)4-methoxy-tetrahydro-furo[3,4-b]furan-2-one. SUMMARY The present invention provides an improved Wittig process and the use of (3aR,4S,6aS)4-methoxy-tetrahydro-furo[3,4-b]furan-2-one as an intermediate, more in particular in crystalline form, in the preparation of diastereomerically pure (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol, which is suitable for industrial scaling up. The present invention provides a novel alkoxy-acetal epimerization of compound of formula β-(4) to the compound of formula α-(4) which significantly contributes into a cost-effective process for the preparation of diastereomerically pure (3R,3aS,6aR) hexahydro-furo[2,3-b]furan-3-ol. The present invention provides furthermore a simultaneous crystallization and epimerization for the isolation of diastereomerically pure (3aR,4S,6aS)4-methoxy-tetrahydro-furo[3,4-b]furan-2-one. Another embodiment of the invention provides with a method that allows the production of (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol in a yield higher than for the methods described in the state of the art. Another object of the present invention is to provide with crystallizable and highly pure intermediate compounds, which are useful in the synthesis of diastereomerically pure (3R,3aS,6aR)hexahydro-furo[2,3-]furan-3-ol. DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for the synthesis of (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol having the structure of formula (6), which method comprises the use of intermediates of formula (4). The present invention also relates to a method for the synthesis of (3R,3aS,6aR) hexahydro-furo[2,3-b]furan-3-ol having the structure of formula (6), which method comprises the use of intermediate of formula α-(4). The present invention further relates to a method for the synthesis of (3R,3aS,6aR) hexahydro-furo[2,3-b]furan-3-ol having the structure of formula (6), which method comprises the steps of: a) treating compound of formula (3) with a base and subsequently with an acid in the presence of methanol, wherein P1 and P2 are each independently a hydrogen, a hydroxy-protecting group or may together form a vicinal-diol protecting group, R1 is alkyl, aryl or aralkyl; resulting in intermediates of formula (4); and b) reducing intermediates of formula (4) with a reducing agent and applying an intramolecular cyclization reaction to obtain compound of formula (6). In one embodiment, the present invention relates to a method for the synthesis of (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol having the structure of formula (6), which comprises the steps of: a) treating compound of formula (3) with a base and subsequently with an acid in the presence of methanol, wherein P1 and P2 are as defined above, R1 is as defined above; resulting in intermediates of formula (4); b) crystallizing with a solvent intermediate of formula α-(4); and c) reducing intermediate of formula α-(4) with a reducing agent and applying an intramolecular cyclization reaction to obtain compound of formula (6). In another embodiment, the present invention relates to the epimerization with acid of compound of formula β-(4) into compound of formula α-(4). In another embodiment, the present invention relates to a method for the synthesis of (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol having the structure of formula (6), which comprises the steps of: a) treating intermediate of formula (3) with a base and subsequently with an acid in the presence of methanol; wherein P1 and P2 are as defined above, R1 is as defined above; resulting in intermediates of formula (4); b) epimerizing with acid the intermediate of formula β-(4) into the intermediate of formula α-(4); c) crystallizing with a solvent intermediate of formula α-(4); and d) reducing intermediate of formula α-(4) with a suitable reducing agent and applying an intramolecular cyclization reaction to obtain compound of formula (6). In another embodiment, the present invention relates to a method for the synthesis of (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol having the structure of formula (6), which comprises the steps of: a) treating said intermediate of formula (3) with a base and subsequently with an acid in the presence of methanol; wherein P1 and P2 are as defined above, R1 is as defined above; resulting in intermediates of formula (4); b) crystallizing with a solvent intermediate of formula α-(4); c) epimerizing with acid the intermediate of formula β-(4) in the mother liquor of above-mentioned crystallization into the intermediate of formula α-(4); d) crystallizing with a solvent intermediate of formula α-(4), giving a second crop of intermediate of formula α-(4); and e) reducing intermediate of formula α-(4) with a suitable reducing agent and applying an intramolecular cyclization reaction to obtain compound of formula (6). In yet another embodiment, the present invention relates to a method for the synthesis of (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol of formula (6), as described in the methods above wherein the epimerization and crystallization of compound of formula α-(4) occur simultaneously. The present invention further provides a method for the synthesis of (3R,3aS,6aR) hexahydro-furo[2,3-b]furan-3-ol of formula (6), as described in the methods above wherein compound of formula (3) is obtained by reacting compound of formula (2) with nitromethane and a base. And yet in another embodiment, the present invention provides a method for the synthesis of (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol of formula (6), as described in the methods above wherein compound of formula (2) is obtained by condensing an intermediate of formula (1), or its hydrate, hemihydrate or a mixture thereof, with phosphonates of the formula (R6O)2P(═O)—CH2—C(═O)OR1, wherein P1 and P2 are as defined above, R1 is as defined above, R6 is alkyl, aryl or aralkyl, The term “hydroxy-protecting group” as used herein refers to a substituent which protects hydroxyl groups against undesirable reactions during synthetic procedures such as those O-protecting groups disclosed in Greene and Muts, “Protective Groups In Organic Synthesis,” (John Wiley & Sons, New York, 3rd edition, 1999). Hydroxy-protecting groups comprise substituted methyl ethers, for example, methoxymethyl, benzyloxymethyl, 2-methoxyethoxymethyl, 2-(trimethylsilyl)ethoxymethyl, t-butyl, benzyl and triphenylmethyl; tetrahydropyranyl ethers; substituted ethyl ethers, for example, 2,2,2-trichloroethyl; silyl ethers, for example, trimethylsilyl, t-butyl-dimethylsilyl and t-butyldiphenylsilyl; and esters, for example, acetate, propionate, benzoate and the like. The term “vicinal-diol protecting group” as used herein refers to protecting groups in the acetal or ketal form and in the orthoester form. Specific examples of the protecting group in the acetal or ketal radical form include methylene, diphenylmethylene, ethylidene, 1-t-butylethylidene, 1-phenylethylidene, (4-methoxyphenyl)ethylidene, 2,2,2-trichloroethylidene, isopropylidene, cyclopentylidene, cyclohexylidene, cycloheptylidene, benzylidene, p-methoxybenzylidene, 2,4-dimethoxybenzylidene, 3,4-dimethoxybenzylidene, 2-nitrobenzylidene, etc. and specific examples of the protecting group in the orthoester form include methoxymethylene, ethoxymethylene, 1-methoxyethylidene, 1-ethoxyethylidene, 1,2-dimethoxy-ethylidene, alpha-methoxybenzylidene, 1-(N,N-dimethylamino) ethylidene, alpha-(N,N-dimethylamino) benzylidene, 2-oxacyclopentylidene, etc. In a preferred embodiment, the vicinal-diol protecting group is isopropylidene. The term “alkyl” as used herein alone or as part of a group refers to saturated monovalent hydrocarbon radicals having straight or branched hydrocarbon chains or, in the event that at least 3 carbon atoms are present, cyclic hydrocarbons or combinations thereof and contains 1 to 20 carbon atoms (C1-20alkyl), suitably 1 to 10 carbon atoms (C1-10alkyl), preferably 1 to 8 carbon atoms (C1-8alkyl), more preferably 1 to 6 carbon atoms (C1-4alkyl), and even more preferably 1 to 4 carbon atoms (C1-4alkyl). Examples of alkyl radicals include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isoamyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and the like. The term “alkenyl” as used herein alone or as part of a group refers to monovalent hydrocarbon radicals having a straight or branched hydrocarbon chains having one or more double bonds and containing from 2 to about 18 carbon atoms, preferably from 2 to about 8 carbon atoms, more preferably from 2 to about 5 carbon atoms. Examples of suitable alkenyl radicals include ethenyl, propenyl, alkyl, 1,4-butadienyl and the like. The term “alkynyl” as used herein alone or as part of a group refers to monovalent hydrocarbon radicals having a straight or branched hydrocarbon chains having one or more triple bonds and containing from 2 to about 10 carbon atoms, more preferably from 2 to about 5 carbon atoms. Examples of alkynyl radicals include ethynyl, propynyl, (propargyl), butynyl and the like. The term “aryl” as used herein, alone or as part of a group, includes an organic radical derived from an aromatic hydrocarbon by removal of one hydrogen, and includes monocyclic and polycyclic radicals, such as phenyl, biphenyl, naphthyl. The term “alkoxy” as used herein, alone or as part of a group, refers to an alkyl ether radical wherein the term alkyl is as defined above. Examples of alkyl ether radical include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy and the like. The terms “aralkyl” and “aralkoxy” as used herein, alone or in combination, mean an alkyl or alkoxy radical as defined above in which at least one hydrogen atom is replaced by an aryl radical as defined above, such as benzyl, benzyloxy, 2-phenylethyl, dibenzylmethyl, hydroxyphenylmethyl, methylphenylmethyl, and the like. The term “aralkoxycarbonyl” as used herein, alone or in combination, means a radical of the formula aralkyl-O—C(O)— in which the term “aralkyl” has the meaning given above. Examples of an aralkoxycarbonyl radical are benzyloxycarbonyl and 4-methoxy-phenylmethoxycarbonyl. The term “cycloalkyl” as used herein, alone or in combination, means a saturated or partially saturated monocyclic, bicyclic or tricyclic alkyl radical wherein each cyclic moiety contains from about 3 to about 8 carbon atoms, more preferably from about 3 to about 6 carbon atoms. Examples of such cycloalkyl radicals include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and the like. The term “cycloalkylalkyl” as used herein, alone or in combination, means an alkyl radical as defined above which is substituted by a cycloalkyl radical as defined above. Examples of such cycloalkylalkyl radicals include cyclopropylmethyl, cyclobutyl-methyl, cyclopentylmethyl, cyclohexylmethyl, I cyclopentylethyl, 1-cyclohexylethyl, 2-cyclopentylethyl, 2-cyclohexylethyl, cyclobutylpropyl, cyclopentylpropyl, cyclohexylbutyl and the like. The terms “heterocycloalkyl” as used herein, alone or in combination, refers to a saturated or partially unsaturated monocyclic, bicyclic or tricyclic heterocycle having preferably 3 to 12 ring members, more preferably 5 to 10 ring members and most preferably 5 to 6 ring members, which contains one or more heteroatom ring members selected from nitrogen, oxygen and sulphur, and which is optionally substituted on one or more carbon atoms by halogen, alkyl, alkoxy, hydroxy, oxo, aryl, aralkyl and the like, and/or on a secondary nitrogen atom (i.e., —NH—) by hydroxy, alkyl, aralkoxy-carbonyl, alkanoyl, phenyl or phenylalkyl and/or on a tertiary nitrogen atom (i.e., ═N—) by oxido. Heterocycloalkyl also includes benzfused monocyclic cycloalkyl groups having at least one such heteroatom. Heterocycloalkyl in addition to sulfur and nitrogen also includes sulfones, sulfoxides and N-oxides of tertiary nitrogen containing heterocycloalkyl groups. The term “heteroaryl” as used herein, alone or in combination, refers to an aromatic monocyclic, bicyclic, or tricyclic heterocycloalkyl radical as defined above and is optionally substituted as defined above with respect to the definitions of aryl and heterocycloalkyl. Examples of such heterocycloalkyl and heteroaryl groups are pyrrolidinyl, piperidinyl, piperazinyl, morpholinyl, thiamorpholinyl, pyrrolyl, imidazol-4-yl, 1-benzyloxy-carbonylimidazol-4-yl, pyrazolyl, pyridyl, 2-(1-piperidinyl)-pyridyl, 2-(4-benzyl-piperazin-1-yl-1-pyridinyl), pyrazinyl, pyrimidinyl, furyl, tetrahydrofuryl, thienyl, triazolyl, oxazolyl, thiazolyl, 2-indolyl, 2-quinolinyl, 3-quinolinyl, 1-oxido-2-quinolinyl, isoquinolinyl, 1-isoquinolinyl, 3-isoquinolinyl, tetrahydroquinolinyl, 1,2,3,4-tetrahydro-2-quinolyl, 1,2,3,4-tetrahydroisoquinolinyl, 1,2,3,4-tetrahydro-1-oxo-isoquinolinyl, quinoxalinyl, 2-benzofurancarbonyl, 1-, 2-, 4- or 5-benzimidazolyl, and the like. The term “silyl” as used herein refers to a silicon atom optionally substituted by one or more alkyl, aryl and aralkyl groups. The terms “isomer”, “isomeric form”, “stereochemically isomeric forms” or “stereoisomeric forms”, as used herein, defines all possible isomeric as well as conformational forms, made up of the same atoms bonded by the same sequence of bonds but having different three-dimensional structures which are not interchangeable, which compounds or intermediates obtained during said process may possess. Unless otherwise mentioned or indicated, the chemical designation of a compound encompasses the mixture of all possible stereochemically isomeric forms which said compound may possess. Said mixture may contain all diastereoisomers, epimers, enantiomers and/or conformers of the basic molecular structure of said compound. More in particular, stereogenic centers may have the R- or S-configuration, diastereoisomers may have a syn- or anti-configuration, substituents on bivalent cyclic saturated radicals may have either the cis- or trans-configuration and alkenyl radicals may have the E or Z-configuration. All stereochemically isomeric forms of said compound both in pure form or in admixture with each other are intended to be embraced within the scope of the present invention. The term “diastereomer” or “diastereomeric form” applies to molecules with identical chemical constitution and containing more than one stereocenter, which differ in configuration at one or more of these stereocenters. The term “epimer” in the present invention refers to molecules with identical chemical constitution and containing more than one stereocenter, but which differ in configuration at only one of these stereocenters. In particular, the term “epimer” is intended to include compounds of formula (4) which differ in the orientation of the bond between carbon 4 (C-4), and the methoxy substituent, i.e. compounds of formula α-(4) and β-(4), respectively, where the C-4 is 4S and 4R, respectively. Pure stereoisomeric forms of the intermediate of formula (1), (4), (6) and of the starting material as mentioned herein are defined as isomers substantially free of other enantiomeric or diastereomeric forms of the same basic molecular structure of said compounds or starting material. Suitably, the term “stereoisomerically pure” compounds or starting material relates to compounds or starting material having a stereoisomeric excess of at least 50% (i.e. minimum 75% of one isomer and maximum 25% of the other possible isomers) up to a stereoisomeric excess of 100% (i.e. 100% of one isomer and none of the other), preferably, compounds or starting material having a stereoisomeric excess of 75% up to 100%, more preferably, compounds, starting material or reagents having a stereoisomeric excess of 90% up to 100%, even more preferred compounds or intermediates having a stereoisomeric excess of 94% up to 100% and most preferred, having a stereoisomeric excess of 97% up to 100%. The terms “enantiomerically pure” and “diastereomerically pure” should be understood in a similar way, but then having regard to the enantiomeric excess, respectively the diastereomeric excess of the mixture in question. As such, a preferred embodiment employs S-2,3-O-isopropylidene-glyceraldehyde as starting material in an enantiomeric excess of more than 95%, more preferably in an enantiomeric excess of more than 97%, even more preferably in an enantiomeric excess of more than 99%. Compounds of Formula (1) Compounds of formula (1) may be obtained from commercially available sources. The synthesis of compounds of formula (1) either in enantiomerically pure form or in racemic form has been described in the literature. For example, the preparation of 2,3-O-isopropylidene-S-glyceraldehyde is described in C. Hubschwerlen, Synthesis 1986, 962; the preparation of 2,3-O-isopropylidene-R-glyceraldehyde is described in C. R. Schmid et al., J. Org. Chem. 1991, 56, 4056-4058; and the preparation of 2,3-O-isopropylidene-(R,S)-glyceraldehyde is described in A. Krief et al., Tetrahedron Lett. 1998, 39, 1437-1440. Thus, said intermediate of formula (1) may be purchased, prepared prior to the reaction or formed in situ. In a preferred embodiment, said compound is formed in situ by, for instance, oxidation in aqueous or partially aqueous solution. In case said compound is in aqueous or partially aqueous solution it is usually partially present in the hydrate or hemihydrate forms thereof. Suitably, the invention relates to a method wherein P1 and P2 together form a vicinal-diol protecting group, and particularly, which is an acid labile protecting group that remains unaffected during the base treatment step of the subsequent Nef reaction. Preferably, said vicinal-diol protecting group is selected from the group consisting of methylene, diphenylmethylene, ethylidene, 1-t-butylethylidene, 1-phenylethylidene, (4-methoxyphenyl)ethylidene, 2,2,2-trichloroethylidene, isopropylidene, cyclopentylidene, cyclohexylidene, cycloheptylidene, benzylidene, p-methoxybenzylidene, 2,4-dimethoxybenzylidene, 3,4-dimethoxybenzylidene and 2-nitrobenzylidene. In a more preferred embodiment, P1 and P2 together form a dialkyl methylene such as an isopropylidene or a 3-pentylidene radical. In the most preferred embodiment P1 and P2 together form an isopropylidene radical. A specific advantage of the use of isopropylidene compared to other protecting groups is that the reagents required for the diol protection, i.e. dimethoxypropane, 2-methoxypropene or acetone, are commercially available and inexpensive. Interesting vicinal-diol protecting groups are those protecting groups that do not cause one or more additional stereogenic centers in the intermediates of formula (1), (2), and (3). The above-mentioned hydroxy-protecting group and vicinal-diol protecting groups can be readily cleaved by methods known in the art such as hydrolysis, reduction, etc., which are appropriately selected depending on the protecting group used. According to a more preferred embodiment, the vicinal-diol protecting group is an acid labile protecting group, wherein the term “acid labile” as used herein refers to vicinal-diol protecting groups that are readily cleaved using acidic conditions. Compounds of Formula (2) Compounds of formula (1) or their hydrate, hemihydrate or mixtures thereof are subsequently transformed to compounds of formula (2) by means of phosphonates in the presence of a base. The reaction employs phosphonates of the formula (R6O)2P(═O)—CH2—C(═O)OR1, wherein R1 is alkyl, aryl or aralkyl, R6 is alkyl, aryl or aralkyl. Suitably, R1 is C1-6alkyl, aryl or arylC1-6alkyl, in particular, C1-6alkyl, more in particular, R1 is methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl and pentyl, preferably, R1 is methyl, ethyl or tert-butyl, and most preferably R1 is ethyl. Examples of phosphonates include ethyl 2-(diethylphosphono)propionate, ethyl 2-(dimethylphosphono)propionate, triethyl phosphonoacetate (TEPA), amongst others. Preferably, compound of formula (1) and the phosphonate are present in the reaction mixture in a range of about 0.9:1.1 to about 1.1:0.9 molar ratio, most preferably in a molar ratio of about 1:1. When compound of formula (1) is prepared in situ, its contents in the reaction mixture should be determined and based thereupon about 1 equivalent of phosphonate is added. Suitable temperatures for the condensation reaction range between about −5° C. and about 50° C., preferably between about 2° C. and about 35° C., more preferably between about 0° and about 25° C. Examples of suitable bases that may be employed for the conversion of compound of formula (1) into compounds of formula (2) include, but are not limited to, alkylamines, sodium, potassium, lithium or cesium carbonates or sodium, potassium, lithium or cesium hydroxide or alkoxides, and mixtures thereof. Preferably the base is potassium carbonate, even more preferably, the base is added as a solid and not as a solution in water. Also more preferably, the amount of potassium carbonate as a solid is at least about 2.5 equivalents based on compound of formula (1). Preferably the pH of the reaction mixture is kept within a range of about 7 to about 13, more preferably within a range of about 8 to about 12, even more preferably the pH is kept between about 9 and about 11. Suitable solvents for this reaction are water, any hydrocarbon, ether, halogenated hydrocarbon, or aromatic solvents known in the art for condensation reactions. These would include, but are not limited to, pentane, hexane, heptane, toluene, xylene(s), benzene, mesitylene(s), t-butylmethyl ether, dialkyl ethers (ethyl, butyl), diphenyl ether, chlorobenzene, methylene chloride, chloroform, carbon tetrachloride, acetonitrile, dichlorobenzene, dichloroethane, trichloroethane, cyclohexane, ethylacetate, isopropyl acetate, tetrahydrofuran, dioxane, methanol, ethanol, and isopropanol. Preferably water is used as the solvent, either as the only solvent or as a mixture with another solvent, for instance with tetrahydrofuran. In one embodiment, a work-up procedure may be applied on the reaction mixture containing compounds of formula (2) by separating the organic and aqueous phases and subsequently extracting from the aqueous phase an additional portion of compounds of formula (2) with an organic solvent, different from the organic phase. As such, the tetrahydrofuran phase may be separated from the aqueous phase and the latter may be extracted with for instance two portions of toluene. Preferred solvents for the extraction are ethyl acetate, toluene, tetrahydrofuran. Most preferred solvent is toluene. Compounds of formula (2) are preferably not purified on silica gel. Although this produces less pure compounds of formula (2) than the silica-gel purified product, the quality is sufficient to produce compound of formula (4) with satisfactory quality and yield. The non-purification eventually aids in simplifying the industrial process of the present invention. Compounds of formula (2) can be obtained in 2 isomeric forms, the E and the Z isomers with E being the preferred isomer. Compounds of Formula (3) Compounds of formula (2) can be subsequently submitted to a Michael addition, in which nitromethane is added as a formyl group precursor to the α,β-unsaturated ester intermediates of formula (2), together with a base. Nitromethane is commercially available as a solution in methanol, and is preferred in such composition. Examples of bases that are suitable for catalyzing Michael additions are sodium, potassium, lithium, cesium hydroxide or alkoxides, TBAF (tetra-n-butylammonium fluoride), DBU (1,8-diazabicyclo[5.4.0]undec-7-ene), TMG (1,1,3,3-tetramethyl-guanidine), preferably sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium methoxide, lithium methoxide, TBAF, DBU, TMG and mixtures thereof, more preferably DBU and TMG and most preferably DBU. When DBU is employed as the base in the conversion of compounds of formula (2) to compounds of formula (3), suitably the amount of base added is higher than about 0.5 equivalents based on compounds of formula (2), more preferably higher than about 0.8 equivalents, even more preferably between about 0.8 and about 1.2 equivalents, most preferably between about 0.9 and about 1.1 equivalents. In a preferred embodiment, DBU is present in approximately 1 equivalent. Any solvent suitable for carrying out a Michael addition may be employed. Examples of suitable solvents are methanol, ethanol and acetonitrile. Preferably, the solvent is methanol, which allows the performance of a one-pot procedure with the subsequent transformations of the obtained compounds of formula (3) into compounds of formula (4). The syn addition form of the compound of formula (3) is predominantly present. The syn/anti ratio is approximately 8/2. Compounds of Formula (4) Compounds of formula (4), i.e. α-(4) and β-(4), are obtained by a number of transformations starting from compounds of formula (3) and consisting of a Nef reaction into the corresponding formyl derivative, simultaneous acid-catalyzed deprotection of the diol and two cyclization reactions. These transformations are accomplished by treating intermediates of formula (3) with a base and subsequently treating the reaction mixture with an acid in the presence of methanol, preferably by adding or pouring the reaction mixture to an acid in the presence of methanol, resulting in intermediates of formula (4). The reactions mentioned above also produce compounds of formula (4′). In the Nef reaction, a primary or a secondary nitroalkane is converted into the corresponding carbonyl compound (N. Komblum Organic reactions 1962, 12, 101 and H. W. Pinnick Organic Reactions 1990, 38, 655). In the classical procedure, the nitroalkane is deprotonated with a base at the α-position to the nitro function, followed by acid-catalyzed hydrolysis of the intermediate ‘nitronate’ salt via addition to a strong acid present in excess, to give the carbonyl derivative. Suitable bases may be selected by one of skill in the art of organic synthesis. Suitable bases include, but are not limited to, inorganic bases such as alkali metal, alkali earth metal, and ammonium hydroxides and alkoxides. Examples of suitable bases are lithium diisopropyl amide, sodium methoxide, potassium methoxide, lithium methoxide, potassium t-butoxide, calcium dihydroxide, barium dihydroxide, and quaternary alkylammonium hydroxides, DBN (1,3-diazabicyclo [3.4.0]non-5-ene), DBU, DABCO (1,4-diazabicyclo[2.2.2]octane), TBAF, TMG, potassium carbonate and sodium carbonate or mixtures thereof. Preferred bases are sodium methoxide, potassium methoxide, lithium methoxide, TBAF, DBU, TMG, or mixtures thereof, more preferred bases are sodium methoxide, lithium methoxide, DBU or TMG or mixtures thereof, and most preferred is sodium methoxide. As an acid, any acid may be employed, preferably a strong acid, more preferably a mineral acid such as concentrated sulfuric acid, concentrated hydrochloric acid, and most preferably concentrated sulfuric acid. By using anhydrous conditions or almost anhydrous conditions and methanol as the solvent in the Nef reaction, the cyclic methyl acetal of the formyl group is obtained. The methyl substituents in the intermediates of formula (4) and (4′) originate from the methanol solvent. Alternatively, if the Nef and the previous Michael addition are carried out in a non-methanolic solvent, for example acetonitrile, other acetals than compounds of formula (4) and (4′) will be obtained instead, usually a mixture of the hemiacetals and the alkyl acetals corresponding to the R1 substituent in compounds of formula (3). Said hemiacetal and acetal congeners may be transformed into the desired methyl acetals of formula (4) and (4′) by newly reacting those with methanol under acidic conditions. Alternatively, when the previous Michael addition is performed with DBU or TMG and compounds of formula (3) are not isolated and the subsequent Nef reaction is carried out with a strong base, in particular with sodium methoxide or lithium methoxide, surprisingly a significant increase in the yield of compounds of formula (4) is obtained. As such, the presence of DBU or TMG during the Nef reaction with a strong base is a preferred embodiment of this invention. For instance, when the Michael addition with nitromethane is carried out in methanol with hydroxides, alkoxides or TBAF in various amounts, the yield of compounds of formula (3) based on compounds of formula (2) is approximately 80%. When the subsequent Nef and cyclizations are carried out with non-isolated compounds of formula (3) using sodium methoxide as the additional base and sulphuric acid in methanol as the acidic solution, 43% of compound of formula (4) can be obtained based on compounds of formula (2) with an α(4)/β(4) ratio of at least approximately 3/1. When the Michael addition is carried out with approximately 1 equivalent of DBU or TMG based on compounds of formula (2), the yield of compounds of formula (3) based on compounds of formula (2) is also approximately 80%. However, when the Nef and cyclization reactions are subsequently carried out with non-isolated compounds of formula (3), combined with 1.0 equivalents of sodium or lithium methoxide based on compounds of formula (2), compound of formula (4) may be obtained in 53-58% yield based on compounds of formula (2) with an α(4)/β(4) ratio of at least approximately 3/1. The bicyclic intermediates of formula (4) are the expected cyclization products originating from intermediates of formula (3) in a syn configuration. The intermediates of formula (4′) are the expected reaction products originating from intermediate of formula (3) in the anti configuration, which does not cyclize, and also the expected reaction products originating from intermediate of formula (3) in a syn configuration, since the cyclization of the syn isomers is usually not fully complete. The trans-configuration of the substituents at carbon atom number 3 (C-3) and carbon atom number 4 (C-4) on the tetrahydrofuran ring of intermediate of formula (4′) prevents the lactone ring formation as observed in intermediates of formula (4). Preferably the acidic quench of the Nef and cyclization reactions is performed with an excess of concentrated sulfuric acid, preferably with 2 to 10 equivalents based on compounds of formula (2), more preferably with 2.5 to 5 equivalents, even more preferably with 3 to 4 equivalents and most preferably with approximately 3.5 equivalents, as a 20 wt % to 80 wt % solution in methanol, preferably as a 40 wt % to 60 wt % solution in methanol. A larger excess of sulphuric acid causes a higher alpha/beta ratio for compounds of formula (4) but also requires more base for the subsequent neutralization in the alkaline quench. For instance, when 3.5 equivalents of sulphuric acid based on compounds of formula (2) are used in the acidic quench as a 50 wt % solution in methanol, an α(4)/β(4) ratio of up to 4/1 may be achieved. The acidic quench of the Nef and cyclization reactions can be carried out at temperatures that range between about −40° C. and about 70° C., preferably at temperatures between about −25° C. and about 15° C., more preferably at temperatures between about −20° C. and about 5° C., most preferably at temperatures between about −15° C. and about 0° C. The reaction times can range up to about 24 hours, suitably in a range between about 15 minutes and about 12 hours, even more suitably in a range between about 20 minutes and about 6 hours. For the isolation of compounds of formula (4), an aqueous work-up may be required to remove the salts and part of the intermediates of formula (4′). A base will neutralize the acid previously employed, since acidic aqueous conditions would cause hydrolysis of the methyl acetal of compound of formula (4) to the hemiacetal congener, thus resulting in product loss. As such, isolation of compound of formula (4) is optimally carried out by an alkaline quench reaction, preferably by an aqueous alkaline quench reaction, followed by extraction of compound of formula (4) with a water-immiscible organic solvent. Preferably, the acidic mixture resulting from the Nef and cyclization reactions is added to the alkaline aqueous solution. Since during the alkaline aqueous quench reaction, a large reactor volume is needed, it is preferable to minimize said volume as much as possible. This may be accomplished in different ways, like for instance employing highly soluble bases, or using bases in slurry form. As such, suitable bases for the work-up of compound of formula (4) are a bicarbonate or carbonate, preferably sodium, potassium, lithium or cesium bicarbonate, preferably sodium, potassium, lithium or cesium bicarbonate, even more preferably sodium or potassium bicarbonate, most preferably potassium bicarbonate, either completely in solution or as a slurry. As such, the use of saturated potassium hydrogen carbonate solution for the alkaline quench instead of saturated sodium hydrogen carbonate solution has, due to its higher solubility, the advantage that the volume of the aqueous phase can be further reduced and the formed potassium sulphate has surprisingly a much better filterability than the sodium sulphate. Advantageously, during the alkaline quench the pH is kept between about 2 and about 9, preferably between about 3 and about 8, more preferably between about 3.5 and about 7.5. Also advantageously, at the end of the alkaline quench the pH is set between about 3.5 and about 6, preferably between about 3.5 and about 5, most preferably between about 3.8 and about 4.5. These required pH ranges may be accomplished by the use of carbonates and bicarbonates as indicated above. Optionally, additional base or acid may be used to set the pH at a certain value at the end of the quench reaction. Within the preferred pH range, the methanol can be evaporated from the reaction mixture after the alkaline quench and before the extractions with organic solvent at temperatures between about 0° and about 65°, preferably between about 20° and about 45° C. Under these conditions compounds of formula (4) are not degraded, even when large scale residence times are applied. Methanol removal by evaporation before the extractions with organic solvent has the advantage that the extraction efficiency significantly increases, so that less organic solvent is consumed and the productivity further increases. Suitable organic non-water miscible solvents are any ester, hydrocarbon, ether, halogenated hydrocarbon, or aromatic solvents. These would include, but are not limited to, pentane, hexane, heptane, toluene, xylene(s), benzene, mesitylene(s), t-butylmethyl ether, dialkyl ethers (ethyl, butyl), diphenyl ether, chlorobenzene, dichloromethane, chloroform, carbon tetrachloride, acetonitrile, dichlorobenzene, 1,2-dichloroethane, 1,1,1-trichloroethane, ethyl acetate, isopropyl acetate, preferably ethylacetate. In order to improve the extraction yield of compounds of formula (4), water soluble salts may be added to the mixture prior to extraction. A preferable salt includes NaCl. One advantage of the method disclosed in the present invention when compared to the Knoevenagel route of the prior and is that during the alkaline aqueous quench it is not necessary to simultaneously extract compounds of formula (4) with an organic solvent. The absence of the organic solvent during the alkaline quench further aids in diminishing the reactor volume and the filtration of the inorganic salts formed is much easier. In the Knoevenagel route, the presence of organic solvent during the alkaline quench is required if product loss is to be avoided. To further isolate compound of formula α-(4) in pure form, crystallization of said compound may be applied. Crystallization Compound of formula α-(4) may be crystallized from a solvent, such as organic, inorganic solvents or water, and mixtures thereof. Suitable solvents for crystallization include isopropanol, t-amyl alcohol, t-butanol, ethylacetate, ethanol and methyliso-butylketone. Especially isopropanol, t-amyl alcohol, and t-butanol are preferred as they produce a high crystallization yield and product with high purity. More preferably isopropanol or t-amyl alcohol are used, most preferably isopropylalcohol. If isopropylalcohol is the solvent used in the crystallization, the preferred concentration before the crystallization of compound of formula α-(4) is between about 5 to about 30 wt %, more preferably between about 10 and about 25 wt %, even more preferably between about 15 and about 20 wt %. Crystallization affords compound of formula α-(4) in high purity although small amounts of compound of formula β-(4) may be present, i.e. in less than about 5%, in particular in amounts less than about 3%. Epimerization Compound of formula (4) in its beta isomeric form may be epimerized into compound of formula α-(4) with an acid, for instance with organic or inorganic acids, preferably in the absence of water and in the presence of methanol. Epimerization is preferably performed with MeSO3H in methanol, or any comparable acid with a similar acidic strength since this prevents the formation of side products. Preferably, the amount of MeSO3H in methanol employed ranges between about 0.05 and about 1.5 equivalents, based on compounds of formula (4), more preferably between about 0.1 and about 0.3 equivalents. The temperature for carrying out the epimerization is between about 0° C. and around reflux temperature, preferably between about 20° C. and around reflux temperature, more preferably between about 40° C. and around reflux temperature, even more preferably at around reflux temperature. Several alternatives may exist for some of the processes described above. For instance, in one embodiment, after obtaining a mixture of compound of formula α-(4) and a compound of formula β-(4), the compound of formula α-(4) is crystallized and the synthetic procedure is continued to produce compound of formula (6). In another embodiment, the artisan may choose to crystallize compound of formula α-(4), proceed with an epimerization of the remaining mother liquour, which contains a relatively large amount of the undesired β-(4) epimer, to obtain a mixture with a relatively large amount of the α-(4) epimer, and apply a second crystallization of the α-(4) epimer. For instance, when the crude mixture of compound of formula (4) having a α-(4)/β-(4) ratio ranging between about 3.5/1 to about 4/1, is crystallized, a first crop of α-(4) is isolated and the remaining mother liquor has a α-(4)/β-(4) ratio ranging between about 0.3/1 and about 1.5/1. After epimerization of the β-(4) epimer, the α-(4)/β-(4) ratio in the mother liquor is approximately 3/1 and a second crop of α-(4) is obtained by crystallization having at least a comparable purity as the first crop of α-(4). Alternatively, one may proceed by performing a simultaneous crystallization of the α-(4) epimer and epimerization reaction of the β-(4) to the α-(4) epimer. In another embodiment, one may start by epimerizing the β-(4) to the α-(4) epimer, and subsequently crystallizing the α-(4) epimer. In yet another embodiment, one may start by epimerizing the β-(4) to the α-(4) epimer, subsequently crystallizing the α-(4) epimer, applying a second epimerization of the remaining mother liquour and an additional crystallization giving a second crop of the α-(4) epimer. As such, in one embodiment, the mother liquor of a previous crystallization of compound of formula α-(4) from isopropanol may be epimerized by evaporation of the isopropanol, taking up the residue in methanol and reflux for approximately 30 minutes to about 4 hours with MeSO3H, preferably with about 0.1 to about 0.3 equivalents. If the reaction mixture is subsequently poured into aqueous NaHCO3, extracted with EtOAc and the organic phase solvent-switched to isopropanol, a second portion of pure compound of formula α-(4) may be obtained by crystallization. In a preferred embodiment, a mixture of the α-(4) and β-(4) epimers may be transformed in one step into 100% or almost 100% alpha isomer in 100% or almost 100% yield, so without by-product formation, via a direct crystallization of the α-(4) epimer and simultaneous epimerization of the β-(4) to the α-(4) epimer, also known as crystallization-induced asymmetric transformation. A crystallization-induced asymmetric transformation may be accomplished by solving the mixture of the α-(4) and β-(4) epimers in methanol in the presence of approximately 0.10 equivalents MeSO3H, based on the sum of both epimers, and evaporating the methanol in vacuo at about 30° C. to about 40° C. This embodiment is particularly preferable since the mixture of the α-(4) and β-(4) epimers can be transformed to only the α-(4) epimer in one step which has lower production costs and one batch of α-(4) with homogeneous quality is obtained. In a preferred embodiment neutralization of the acid, such as MeSO3H, is performed prior to the solvent switch from methanol to the crystallization solvent such as isopropanol. Said neutralization may be accomplished by adding a slight molar excess of a base, based on the epimerization acid used. As a base, any base can be used as long as the salt of the base with the epimerization acid does not contaminate the crystals of the α-4) epimer. For instance, in case MeSO3H is used as the epimerization acid, a tertiary amine may be used, preferably triethylamine, giving the triethylammonium methanesulfonate salt, which does not contaminate the crystals of the α-(4) epimer during the crystallization from isopropanol. The addition of a slight excess of NEt3 over MeSO3H for the neutralization, avoids the formation of isopropyl acetals as side products which would be formed under acidic conditions during the subsequent solvent switch from methanol to isopropanol. Subsequent solvent switch from methanol to isopropanol and crystallization gives compound of formula α-(4) in high purity without any or with minimum contamination with triethylammonium methanesulfonate salt. Compound of Formula (6) Compound of formula (6) is obtained by reduction of compound of formula α-(4) followed by a cyclization reaction. The resulting intermediate of the reduction of compound of formula α-(4) is compound of formula (5). Compound of formula (5) is preferably not isolated but directly cyclized to compound of formula (6). The reduction step can conveniently be accomplished by treatment of intermediate of formula α-(4) with metal hydrides such as lithium borohydride, sodium borohydride, sodium borohydride-lithium chloride in suitable anhydrous solvents. Examples of suitable anhydrous solvents include but are not limited to dichloromethane, toluene, xylene, benzene, pentane, hexane, heptane, petrol ether, 1,4-thioxane, diethyl ether, diisopropyl ether, tetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, and in general any anhydrous solvent susceptible to being used in a chemical reduction process using the reduction agents cited above. A preferred solvent is tetrahydrofuran. According to a preferred embodiment, the reduction step is performed using lithium borohydride or sodium borohydride in tetrahydrofuran. In case lithium borohydride is used as the reducing agent, the amount of reducing agent ranges between about 1 and about 1.5 equivalents based on the amount of compound of formula α-(4), preferably between about 1.1 and about 1.3 equivalents. Said reduction step can be carried out at temperatures that range between about −78° C. and about 55° C., preferably between about −15° C. and about 45° C., and most preferably between about 0° C. and about 40° C. The reaction time may range up to about 24 hours, and suitably varies between about 2 and about 24 hours. Compound of formula (5) may be converted to the desired compound of formula (6) by a cyclization reaction. The cyclization reaction occurs via an intramolecular transacetalisation and can be performed in any acid-compatible organic solvent or a combination of a water-miscible solvent and water and in the presence of a strong organic or inorganic acid. Said reaction is suitably performed by treatment of compound of formula (5) with a catalytic amount of a strong acid. In a preferred embodiment, the strong acid is selected from a group consisting of hydrochloric acid and sulfuric acid in tetrahydrofuran. Said cyclization step is preferably carried out at temperatures below about 5° C., more preferably below about −5° C. In a particularly preferred embodiment compound of formula (5), which upon reduction with lithium or sodium borohydride in tetrahydrofuran is obtained as a boron complex, is treated with a concentrated mineral acid and the decomplexation of compound of formula (5) and the cyclization of compound of formula (5) to compound of formula (6) are performed simultaneously. Preferably a strong mineral acid is used, more preferably concentrated sulfuric acid or concentrated hydrochloric acid, most preferably concentrated hydrochloric acid. The amount of hydrochloric acid may vary between 1.0 and 1.4 equivalents based on the applied amount of lithium oar sodium borohydride, but is preferably between 1.1 and 1.3 equivalents. With respect to the isolation of compound of formula (6) in pure form, it is desirable to remove the inorganic salts resulting from the reagents used in the reduction, decomplexation and cyclization steps. This may be done by an aqueous-organic solvent extraction procedure, but preferably this is done by adding a small excess of a base over the acid applied for the decomplexation of compound of formula (5) and cyclization reaction thereof to compound of formula (6). Subsequently, a solvent-switch from to a more apolar solvent is performed resulting in precipitation of the salts resulting from the reduction and decomplexation. As a base used in the work-up of compound of formula (6) any base can be used as long as the solubility of its salt with the mineral acid used for the decomplexation and the cyclization reaction of compound of formula (5) to compound of formula (6) in the final solvent after the solvent-switch is low. For instance, if lithium borohydride in tetrahydrofuran is used in the reduction, concentrated aqueous HCl is used in the decomplexation/cyclization and ethyl acetate is the final solvent, then tertiary amines are suitable bases for the neutralization of the acid, particularly triethylamine. In that case, the boron salts and triethylamine hydrochloride almost fully precipitate and compound of formula (6) fully remains in solution. After filtration of the solids a solution of compound of formula (6) with high purity remains which can be processed to any desired form. It is observed that the other enantiomer of compound of formula (6), namely compound of formula (6d), (3S,3aR,6aS)hexahydro-furo[2,3-b]furan-3-ol, is also an active moiety for HIV protease inhibitors. As such, the identical methods, procedures, reagents and conditions, disclosed in the present invention, including the corresponding crystallization and epimerization, may be applied in the preparation of compound of formula (6d), by employing compounds of formula (1d), precursors thereof, and other intermediates in the preparation of compound of formula (6d), such as compounds of formula (4d) below. The compounds of formula (6) and (6d) find their particular use in the preparation of a medicament. According to a preferred embodiment, the present compounds of formula (6) and (6d) are used as precursors in the preparation of anti-viral drugs, in particular anti-HIV drugs, more in particular HIV protease inhibitors. The compound of formula (6) and all intermediates leading to the formation of said stereoisomerically pure compound are of particular interest in preparing HIV protease inhibitors as disclosed in WO 95/24385, WO 99/65870, WO 00/47551, WO 00/76961 and U.S. Pat. No. 6,127,372, WO 01/25240, EP 0 715 618 and WO 99/67417 all incorporated herein by reference, and in particular, the following HIV-protease inhibitors. [(1S,2R)-2-hydroxy-3-[[(4-methoxyphenyl)sulfonyl](2-methylpropyl)amino]-1-(phenyl-methyl)propyl]-carbamic acid (3R,3aS,6aR)-hexahydrofuro[2,3-b]furan-3-yl ester (HIV protease inhibitor 1); [(1S,2R)-3-[[(4-aminophenyl)sulfonyl](2-methylpropyl)amino]-2-hydroxy-1-(phenyl-methyl)propyl]-carbamic acid (3R,3aS,6aR)-hexahydrofuro[2,3-b]furan-3-yl ester (HIV protease inhibitor 2); [(1S,2R)-3-[(1,3-benzodioxol-5-ylsulfonyl)(2-methylpropyl)amino]-2-hydroxy-1-(phenylmethyl)propyl]-carbamic acid (3R,3aS,6aR)-hexahydrofuro[2,3-b]furan-3-yl ester (HIV protease inhibitor 3), or any pharmaceutically acceptable addition salt thereof. Thus, the present invention also relates to HIV protease inhibitors 1, 2, 3 or any pharmaceutically acceptable salt or prodrug thereof, obtained by using a compound of formula (6) prepared according to the present invention in the chemical synthesis of said HIV protease inhibitors. Such chemical synthesis is disclosed in the literature, for instance in WO 01/25240, EP 0 715 618 and WO 99/67417. As such, the protease inhibitors referred above can be prepared utilizing the following general procedure. An N-protected amino epoxide of the formula wherein P is an amino protecting group, and R2 represents alkyl, aryl, cycloalkyl, cycloalkylalkyl and aralkyl radicals, which radicals are optionally substituted with a group selected from alkyl and halogen radicals, nitro, cyano, trifluoromethyl, —OR9 and —SR9, wherein R9 represents hydrogen, alkyl, and halogen radicals; is prepared from the corresponding chloroketone in the presence of a base and a solvent system. Suitable solvent systems for preparing the amino epoxide include ethanol, methanol, isopropanol, tetrahydrofuran, dioxane, and the like including mixtures thereof. Suitable bases for producing the epoxide from the reduced chloroketone include potassium hydroxide, sodium hydroxide, potassium t-butoxide, DBU and the like. Alternatively, a protected amino epoxide can be prepared starting with an L-amino acid which is reacted with a suitable amino-protecting group in a suitable solvent to produce an amino-protected L-amino acid ester of the formula: wherein P′″ represents a carboxyl-protecting group, for example, methyl, ethyl, benzyl, tertiary-butyl and the like; R2 is as defined above; and P′ and P″ independently are selected from amine protecting groups, including but not limited to, arylalkyl, substituted arylalkyl, cycloalkenylalkyl and substituted cycloalkenylalkyl, allyl, substituted allyl, acyl, alkoxycarbonyl, aralkoxycarbonyl and silyl. Additionally, the P′ and/or P″ protecting groups can form a heterocyclic ring with the nitrogen to which they are attached, for example, 1,2-bis(methylene)benzene, phthalimidyl, succinimidyl, maleimidyl and the like and where these heterocyclic groups can further include adjoining aryl and cycloalkyl rings. In addition, the heterocyclic groups can be mono-, di- or tri-substituted, for example, nitrophthalimidyl. The amino-protected L-amino acid ester is then reduced, to the corresponding alcohol. For example, the amino-protected L-amino acid ester can be reduced with diisobutylaluminum hydride at −78° C. in a suitable solvent such as toluene. Preferred reducing agents include lithium aluminium hydride, lithium borohydride, sodium borohydride, borane, lithium tri-terbutoxyaluminum hydride, borane/THF complex. The resulting alcohol is then converted, for example, by way of a Swern oxidation, to the corresponding aldehyde of the formula: wherein P′, P″ and R2 are as defined above. Thus, a dichloromethane solution of the alcohol is added to a cooled (−75° to −68° C.) solution of oxalyl chloride in dichloromethane and DMSO in dichloromethane and stirred for 35 minutes. Acceptable oxidizing reagents include, for example, sulfur trioxide-pyridine complex and DMSO, oxalyl chloride and DMSO, acetyl chloride or anhydride and DMSO, trifluoroacetyl chloride or anhydride and DMSO, methanesulfonyl chloride and DMSO or tetrahydro thiaphene-S-oxide, toluenesulfonyl bromide and DMSO, trifluoro-methanesulfonyl anhydride (triflic anhydride) and DMSO, phosphorus pentachloride and DMSO, dimethylphosphoryl chloride and DMSO and isobutyl chloroformate and DMSO. The aldehydes of this process can also be prepared by methods of reducing protected phenylalanine and phenylalanine analogs or their amide or ester derivatives by, for example, sodium amalgam with HCl in ethanol or lithium or sodium or potassium or calcium in ammonia. The reaction temperature may be from about −20° C. to about 45° C., and preferably from about 5° C. to about 25° C. Two additional methods of obtaining the nitrogen protected aldehyde include oxidation of the corresponding alcohol with bleach in the presence of a catalytic amount of 2,2,6,6-tetramethyl-1pyridyloxy free radical. In a second method, oxidation of the alcohol to the aldehyde is accomplished by a catalytic amount of tetrapropylammonium perruthenate in the presence of N-methylmorpholine-N-oxide. Alternatively, an acid chloride derivative of a protected phenylalanine or phenylalanine derivative as disclosed above can be reduced with hydrogen and a catalyst such as Pd on barium carbonate or barium sulphate, with or without an additional catalyst moderating agent such as sulfur or a thiol (Rosenmund Reduction). The aldehyde resulting from the Swern oxidation is then reacted with a halomethyl-lithium reagent, which reagent is generated in situ by reacting an alkyllithium or arylithium compound with a dihalomethane represented by the formula X1CH2X2 wherein X1 and X2 independently represent iodine, bromine or chlorine. For example, a solution of the aldehyde and chloroiodomethane in THF is cooled to −78° C. and a solution of n-butyllithium in hexane is added. The resulting product is a mixture of diastereomers of the corresponding amino-protected epoxides of the formulas: The diastereomers can be separated for example, by chromatography, or, alternatively, once reacted in subsequent steps the diastereomeric products can be separated. For compounds having the (S) stereochemistry, a D-amino acid can be utilized in place of the L-amino acid. The addition of chloromethylithium or bromomethylithium to a chiral amino aldehyde is highly diastereoselective. Preferably, the chloromethyllithium or bromomethylithium is generated in situ from the reaction of the dihalomethane and n-butyllithium. Acceptable methyleneating halomethanes include chloroiodomethane, bromochloromethane, dibromomethane, diiodomethane, bromofluoromethane and the like. The sulfonate ester of the addition product of, for example, hydrogen bromide to formaldehyde is also a methyleneating agent. Tetrahydrofuran is the preferred solvent, however alternative solvents such as toluene, dimethoxyethane, ethylene dichloride, methylene chloride can be used as pure solvents or as a mixture. Dipolar aprotic solvents such as acetonitrile, DMF, N-methyl-pyrrolidone are useful as solvents or as part of a solvent mixture. The reaction can be carried out under an inert atmosphere such as nitrogen or argon. For n-butyl lithium can be substituted other organometallic reagents reagents such as methyllithium, tertbutyl lithium, sec-butyl lithium, phenyllithium, phenyl sodium and the like. The reaction can be carried out at temperatures of between about −80° C. to 0° C. but preferably between about −80° C. to −20° C. The conversion of the aldehydes into their epoxide derivative can also be carried out in multiple steps. For example, the addition of the anion of thioanisole prepared from, for example, a butyl or aryl lithium reagent, to the protected aminoaldehyde, oxidation of the resulting protected aminosulfide alcohol with well known oxidizing agents such as hydrogen peroxide, tert-butyl hypochlorite, bleach or sodium periodate to give a sulfoxide. Alkylation of the sulfoxide with, for example, methyl iodide or bromide, methyl tosylate, methyl mesylate, methyl triflate, ethyl bromide, isopropyl bromide, benzyl chloride or the like, in the presence of an organic or inorganic base. Alternatively, the protected aminosulfide alcohol can be alkylated with, for example, the alkylating agents above, to provide a sulfonium salts that are subsequently converted into the subject epoxides with tertamine or mineral bases. The desired epoxides formed, using most preferred conditions, diastereoselectively in ratio amounts of at least about an 85:15 ratio (S:R). The product can be purified by chromatography to give the diastereomerically and enantiomerically pure product but it is more conveniently used directly without purification to prepare retroviral protease inhibitors. The foregoing process is applicable to mixtures of optical isomers as well as resolved compounds. If a particular optical isomer is desired, it can be selected by the choice of starting material, for example, L-phenylalanine, D-phenylalanine, L phenylalaminol, D-phenylalaminol, D-hexahydrophenylalaminol and the like, or resolution can occur at intermediate or final steps. Chiral auxiliaries such as one or two equivalents of camphor sulfonic acid, citric acid, camphoric acid, 2-methoxy-phenyl-acetic acid and the like can be used to form salts, esters or amides of the compounds of this invention. These compounds or derivatives can be crystallized or separated chromatographically using either a chiral or achiral column as is well known to those skilled in the art. The amino epoxide is then reacted, in a suitable solvent system, with an equal amount, or preferably an excess of, a desired amine of the formula R3NH2, wherein R3 is hydrogen, alkyl, haloalkyl, alkenyl, alkynyl, hydroxyalkyl, alkoxyalkyl, cycloalkyl, cycloalkylalkyl, heterocycloalkyl, heteroaryl, heterocycloalkylalkyl, aryl aralkyl, heteroaralkyl, aminoalkyl and mono- and di-substituted aminoalkyl radicals, wherein said substituents are selected from alkyl, aryl, aralkyl, cycloalkyl, cycloalkylalkyl, heteroaryl, heteroaralkyl, heterocycloalkyl, and heterocycloalkylalkyl radicals, or in the case of a disubstituted aminoalkyl radical, said substituents along with the nitrogen atom to which they are attached, form a heterocycloalkyl or a heteroaryl radical. The reaction can be conducted over a wide range of temperatures, for example, from about 110° C. to about 100° C., but is preferably, but not necessarily, conducted at a temperature at which the solvent begins to reflux. Suitable solvent systems include protic, non-protic and dipolar aprotic organic solvents such as, for example, those wherein the solvent is an alcohol, such as methanol, ethanol, isopropanol, and the like, ethers such as tetrahydrofuran, dioxane and the like, and toluene, N,N-dimethylformamide, dimethyl sulfoxide, and mixtures thereof. A preferred solvent is isopropanol. Exemplary amines corresponding to the formula R3NH2 include benzylamine, isobutylamine, n-butylamine, isopentylamine, isoamylamine, cyclohexanemethylamine, naphthylene methylamine and the like. The resulting product is a 3-(N-protected-amino)-3-(R2)-1-(NHR3)-propan-2-ol derivative, hereinafter referred to as an amino alcohol, and represented by the formulas: wherein P, P′, P″, R2 and R3 are as described above. Alternatively, a haloalcohol can be utilized in place of the amino epoxide. The amino alcohol defined above is then reacted in a suitable solvent with a sulfonyl chloride (R4SO2Cl) or sulfonyl anhydride in the presence of an acid scavenger. Suitable solvents in which the reaction can be conducted include methylene chloride, tetrahydrofuran. Suitable acid scavengers include triethylamine, pyridine. Preferred sulfonyl chlorides are methanesulfonyl chloride and benzenesulfonyl chloride. The resulting sulfonamide derivative can be represented, depending on the epoxide utilized by the formulas wherein P, P′, P″, R2, R3 and R4 are as defined above. These intermediates are useful for preparing protease inhibitor compounds and are also active inhibitors of retroviral proteases. The sulfonyl halides of the formula R4SO2X can be prepared by the reaction of a suitable Grignard or alkyl lithium reagent with sulfuryl chloride, or sulfur dioxide followed by oxidation with a halogen, preferably chlorine. Also, thiols may be oxidized to sulfonyl chlorides using chlorine in the presence of water under carefully controlled conditions. Additionally, sulfonic acids may be converted to sulfonyl halides using reagents such as PCl5, and also to anhydrides using suitable dehydrating reagents. The sulfonic acids may in turn be prepared using procedures well known in the art. Such sulfonic acids are also commercially available. In place of the sulfonyl halides, sulfinyl halides (R4SOX) or sulfenyl halides (R4SX) can be utilized to prepare compounds wherein the —SO2— moiety is replaced by an —SO— or —S— moiety, respectively. Following preparation of the sulfonamide derivative, the amino protecting group P or P′ and P″ amino protecting groups are removed under conditions which will not affect the remaining portion of the molecule. These methods are well known in the art and include acid hydrolysis, hydrogenolysis and the like. A preferred method involves removal of the protecting group, for example, removal of a carbobenzoxy group, by hydrogenolysis utilizing palladium on carbon in a suitable solvent system such as an alcohol, acetic acid, and the like or mixtures thereof. Where the protecting group is a t-butoxycarbonyl group, it can be removed utilizing an inorganic or organic acid, for example, HCl or trifluoroacetic acid, in a suitable solvent system, for example, dioxane or methylene chloride. The resulting product is the amine salt derivative of the formula: This amine can be coupled to a carboxylate represented by the formula wherein R is the (3R,3aS,6aR)hexahydrofuro[2,3-b]furan-3-oxy group and L is an appropriate leaving group such as a halide. A solution of the free amine (or amine acetate salt) and about 1.0 equivalent of the carboxylate are mixed in an appropriate solvent system and optionally treated with up to five equivalents of a base such as, for example, N-methylmorpholine, at about room temperature. Appropriate solvent systems include tetrahydrofuran, methylene chloride or N,N-dimethyl formamide, and the like, including mixtures thereof. Alternatively the amine can be coupled to an activated (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol succinimidyl carbonate. Activation of (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol may be accomplished for instance by reaction with disuccinimidyl carbonate and triethylamine. EXAMPLES The following examples are meant to be illustrative of the present invention. These examples are presented to exemplify the invention and are not to be construed as limiting the invention's scope. All reactions were performed under nitrogen atmosphere. Solvents and reagents were used as supplied without further purification. 1H NMR spectra were recorded at 200 MHz in CDCl3 or DMSO-d6 on a Bruker AC-200 NMR spectrometer. Quantitative 1H NMR was performed with chlorobenzene as the internal standard. All reported yields have been corrected for the impurity of the product. The gas chromatography (GC) assay and e.e. determination of S-2,3-O-isopropylidene-glyceraldehyde in reaction mixtures was performed with an Agilent 6890 GC (EPC) and a Betadex column (part number 24305, Supelco or equivalent) of 60 m and with a film thickness of 0.25 μm using a column head pressure of 26.4 kPa, a column flow of 1.4 mL/min, a split flow of 37.5 mL/min and an injection temperature of 150° C. The used ramp was: initial temperature 60° C. (3 min), rate 5° C./min, intermediate temperature 130° C. (1 min), rate 25° C./min, final temperature 230° C. (8 min). Detection was performed with an FID detector at a temperature of 250° C. The retention times were as follows: chlorobenzene (internal standard) 13.9 min, S-2,3-O-isopropylidene-glyceraldehyde 15.9 min, R-2,3-O-isopropylidene-glyceraldehyde 16.2 min. The GC assay and e.e. determination of R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethyl ester was performed with above-described equipment but using an injection temperature of 250° C. The used ramp was: initial temperature 80° C. (1 min), rate 5° C./min, final temperature 225° C. (10 min). Detection was performed with a FID detector at a temperature of 250° C. The retention times were as follows: toluene 7.3 min, chlorobenzene (internal standard) 9.4 min, S-2,3-O-isopropylidene-glyceraldehyde 10.7 ml, R-2,3-O-isopropylidene-glyceraldehyde 10.9 min, Z-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethyl ester 20.4 min, E-R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethyl ester 22.6 min, E-S-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethyl ester 22.9 min, triethyl phosphonoacetate (TEPA) 25.5 min. The GC assay for compounds α-(4) and β-(4) was performed with an Agilent 6890 GC (EPC) and a CP-Sil 5 CB column (part number CP7680 (Varian) or equivalent) of 25 m and with a film thickness of 5 μm using a column head pressure of 5.1 kPa, a split flow of 40 mL/min and an injection temperature of 250° C. The used ramp was: initial temperature 50° C. (5 min), rate 10° C./min, final temperature 250° C. (15 min). Detection was performed with an FID detector at a temperature of 250° C. The retention times were as follows: chlorobenzene (internal standard) 17.0 min, α-(4) 24.9 min, β-(4) 25.5 min. Example 1 Preparation of S-2,3-O-isopropylidene-glyceraldehyde and conversion to R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester To a well-stirred slurry of KIO4 (530 g, 2.3 mol, 2.3 eq.), KHCO3 (230 g, 2.3 mol, 2.3 eq.) in water (1200 g) was added dropwise a solution of L-5,6-O-isopropylidene-gulono-1, 4-lactone (218.5 g, 1 mol) in water (135 g) and tetrahydrofuran (1145 g) during 3 h at 32-34° C. The reaction mixture was stirred for 4.5 h at 32° C. According to GC the oxidation was complete since the S-2,3-O-isopropylidene-glyceraldehyde content was 4.38 wt % and did not increase further. The reaction mixture was cooled to 5° C. and kept at this temperature for 14 h. The solids (mainly consisting of KIO3) were removed by filtration and the cake washed with tetrahydrofuran (115 mL) and with another portion of tetrahydrofuran (215 mL) by reslurrying. A sample was taken from the filtrate (2975 g) and analyzed by quantitative 1H NMR (DMSO-d6) showing that the S-2,3-O-isopropylidene-glyceraldehyde content in the filtrate was 3.69 wt % corresponding to 109.6 g (0.843 mol) and a yield of 84% based on L-5,6-O-isopropylidene-gulono-1,4-lactone. To 2953 g of the obtained filtrate (containing 108.8 g=0.837 mol S-2,3-O-isopropylidene-glyceraldehyde) at 13° C. was added dropwise under stirring triethyl phosphonoacetate (TEPA, 194.7 g, 97% pure, 0.843 mol, 1.01 eq.) during 25 min at 13-17° C. Subsequently, K2CO3 (838 g, 6.07 mol, 7.26 eq.) was added portionwise during 30 min at 17-25° C. The final pH of the reaction mixture was 11.6. The reaction mixture was stirred for another 17 h at 20° C. The aqueous and tetrahydro-furan phases were separated and the aqueous phase extracted twice with 660 mL of toluene. The combined tetrahydrofuran and toluene phases were concentrated in vacuo (260-25 mbar, temperature 28-56° C.) during 8 h giving 175.5 g of a light yellow liquid. Quantitative 1H NMR indicated the presence of 78 wt % E-R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester, 2.5 wt % Z-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester, 4.4 wt % TEPA (4.1 mole % of the initial amount) and 6.8 wt % toluene. This corresponds with a total R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester yield of 141.2 g (0.706 mol) being 71% yield based on L-5,6-O-isopropylidene-gulono-1,4-lactone and 84% yield based on S-2,3-O-isopropylidene-glyceraldehyde. GC indicated that the e.e. of E-R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester was >99%. Example 2 Preparation of a mixture of compounds α-(4) and β-(4) from R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester using various types and amounts of bases without isolation of the nitro addition compound Example 2A: Use of DBU in the Michael Addition and NaOMe as Additional Base in the Nef Reaction To R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester (21.2 g oil, 94.5 wt % pure, 0.1 mol) was added nitromethane (13.0 g of a 51.7 wt % solution in methanol, 0.11 mol, 1.1 eq.) and the solution was cooled to 0° C. Subsequently, DBU (15.2 g, 0.1 mol, 1 eq.) was added dropwise during 25 min and the funnel was rinsed with methanol (1 g). The reaction mixture was heated up to 20° C. and stirred at that temperature for 17 h. The resulting solution (50 g) was divided in 2 equal parts; the other 25 g part was further processed as described in example 2B. The one 25 g part was cooled to 0° C. and NaOMe (10.0 g of a 29.6 wt % solution in methanol, 0.055 mol, 1.1 eq.) was added dropwise during 10 min at 0° C. and the funnel was rinsed with methanol (1.6 g). The reaction mixture was stirred for 50 min at 0° C. and then quenched into a solution of H2SO4 (17.9 g, 96 wt %, 0.175 mol, 3.5 eq.) in methanol (30.4 g) at 0-5° C. by dropwise addition during 60 min under vigorous stirring. The funnel was rinsed with methanol (2×4 g). The resulting reaction mixture was stirred for 2 h at 0° C. and subsequently quenched into a stirred mixture of saturated aqueous NaHCO3 (300 mL) and ethyl acetate (100 mL) at 0-5° C. by dropwise addition during 15 min. The final pH was 6.9. Another portion of ethyl acetate (50 mL) was added and the pH was adjusted to 4.2 with H2SO4 (96 wt %). After phase separation the aqueous phase was extracted with ethyl acetate (1×150 mL, 3×100 mL). The combined organic phases were concentrated in vacuo at 40-50° C. giving 8.1 g of an orange solid. According to quantitative 1H NMR analysis this solid contained 4.2 g (0.026 mol) of compounds α-(4) and D-(4), corresponding to a total yield of 53% based on R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester. The α-(4):β-(4) ratio was 3.1:1. Example 2B Use of DBU in the Michael Addition and No Additional Base in the Nef Reaction The other 25 g solution as obtained after the Michael addition in example 2A was cooled to 0° C. and quenched into a solution of H2SO4 (7.8 g, 96 wt %, 0.076 mol, 1.5 eq.) in methanol (13.2 g) at 0° C. by dropwise addition during 40 min under vigorous stirring. The funnel was rinsed with methanol (7.7 g). The resulting reaction mixture was stirred for 4 h at 0° C. and subsequently worked up according to the procedure of example 2A giving a solid which, according to quantitative 1H NMR analysis, contained 2.8 g (0.0175 mol) of compounds α-(4) and β-(4), corresponding to a yield of 35% based on R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester. Example 2C Use of TMG in the Michael Addition and NaOMe as Additional Base in the Nef Reaction To R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester (47.5 g oil, 84.2 wt % pure, 0.2 mol) was added nitromethane (26.0 g of a 51.7 wt % solution in methanol, 0.22 mol, 1.1 eq.) and the solution was cooled to 0° C. Subsequently, TMG (23 g, 0.2 mol, 1 eq.) was added dropwise during 20 min and the funnel was rinsed with methanol (2 g). The reaction mixture was heated up to 20° C. and stirred at that temperature for 22 h. The solution was cooled to 0° C. and NaOMe (40.2 g of a 29.6 wt % solution in methanol, 0.22 mol, 1.1 eq.) was added dropwise during 15 min at 0° C. and the funnel was rinsed with methanol (6.4 g). After stirring for another 70 min at 0° C. the mixture was quenched into a solution of H2SO4 (71.6 g, 96 wt %, 0.7 mol, 3.5 eq.) in methanol (121.6 g) at 0-5° C. by dropwise addition during 70 min under vigorous stirring. The funnel was rinsed with methanol (2×15 g). The resulting reaction mixture was stirred for 145 min at 0° C. and subsequently quenched into a stirred mixture of saturated aqueous NaHCO3 (1200 mL) and ethyl acetate (400 mL) at 0° C. by dropwise addition during 30 min. The final pH was 7.4. After adding an additional portion (200 mL) of ethyl acetate the pH was adjusted to 4.2 with H2SO4 (96 wt %). After phase separation the aqueous phase was extracted with ethyl acetate (4×400 mL). The combined organic phases were concentrated in vacuo at 40-50° C. giving 38.5 g of a yellow-orange solid which, according to quantitative 1H NMR analysis, contained α-(4) (12.2 g, 0.077 mol) and β-(4) (4.6 g, 0.029 mol) corresponding to a total yield of 53% based on R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester and an α-(4):β-(4) ratio of 2.7:1. Example 2D Use of Only NaOMe in the Michael Addition and in the Nef Reaction To R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester (47.5 g, 84.2 wt % pure, 0.2 mol) in methanol (200 g) was added nitromethane (26.0 g of a 51.7 wt % solution in methanol, 0.22 mol, 1.1 eq.) and the solution was cooled to 0° C. NaOMe (40 g of a 30 wt % solution in methanol, 0.22 mol, 1.1 eq.) was added and the reaction mixture was stirred for 18 h at 0° C. and then quenched into a solution of H2SO4 (58 g, 96 wt %, 0.57 mol, 2.9 eq.) in methanol (140 g) at −3-0° C. by dropwise addition during 75 min under vigorous stirring. The reaction mixture was stirred for 4 h at 0° C. and subsequently kept for 16 h at −30° C. According to quantitative 1H NMR analysis the total yield (in the reaction mixture) of α-(4) and β-(4) based on R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester was 45% and the α-(4):β-(4) ratio 2.5:1. The reaction mixture was subsequently quenched into a stirred solution of NaHCO3 (80 g) in water (1 L) at 0-5° C. by dropwise addition during 90 min. At the end of the quench a solution of NaRCO3 (4 g) in water (50 mL) was added to adjust the pH to 5-5.5. After phase separation the aqueous solution was extracted with ethyl acetate (4×500 mL) and the combined organic phases were concentrated in vacuo at 30-40° C. giving 32 g of a red oil. According to quantitative 1H NMR analysis, this oil contained 13.2 g (0.084 mol) α-(4) and β-(4) corresponding to a total yield of 42% based on R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester with the α-(4):β-(4) ratio being 3:1. Example 3 Preparation of pure α-(4) from R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester using DBU in the Michael addition, NaOMe as additional base in the Nef reaction and crystallization of α-(4) from isopropanol Example 3A: Using a Non-Improved Work-Up Procedure for α-(4) and β-(4) To R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester (42.3 g, 94.5 wt % pure, 0.2 mol) was added nitromethane (26.0 g of a 51.7 wt % solution in methanol 0.22 mol 1.1 eq.) and the solution was cooled to 0° C. Subsequently, DBU (30.4 g, 0.2 mol, 1 eq.) was added dropwise during 20 min and the funnel was rinsed with methanol (4 g). The reaction mixture was heated up to 20° C., stirred for another 16.5 h at this temperature and subsequently cooled to 0° C. Then, NaOMe (40.4 g of a 29.6 wt % solution in methanol, 0.22 mol 1.1 eq.) was added dropwise during 20 min at 0° C. and the funnel was rinsed with methanol (6.4 g). The resulting solution was stirred for 50 min at 0° C. and then quenched into a solution of H2SO4 (71.6 g, 96 wt %, 0.7 mol, 3.5 eq.) in methanol (121.6 g) at 0-5° C. by dropwise addition during 70 min under vigorous stirring. The funnel was rinsed with methanol (2×16 g) and the reaction mixture was stirred for 2 h at 0-2° C. and then quenched into a stirred mixture of saturated aqueous NaRCO3 solution (1.2 L) and ethyl acetate (400 mL) at 0-9° C. by dropwise addition during 17 min. The final pH was 7.2. The funnel was rinsed with methanol (40 ml) and the pH was adjusted to 4.0 with H2SO4 (96 wt %) at 9° C. After the addition of ethyl acetate (200 mL) and phase separation, the aqueous phase was extracted with ethyl acetate (600 mL, 3×400 mL). The combined organic phases were concentrated in vacuo at 40-50° C. giving 35.9 g of a yellow-orange semi-solid which, according to quantitative 1H NMR analysis, contained 16.5 g (0.104 mol) of α-(4) and β-(4) corresponding to a total yield of 52% based on R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester. The α-(4):β-(4) ratio was 3.0:1. The crude semi-solid product was dissolved in isopropanol (69.5 g) at 80° C. The resulting solution was cooled to 60° C., seeded and cooled further to 0° C. during 2 h which resulted in crystallization of α-(4). The solids were isolated by filtration, washed with isopropanol (30 ml, 20° C.) and dried on the air giving 12.0 g off-white crystalline product which, according to quantitative 1H NMR, consisted of 9.8 g α-(4) (31% yield based on R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester) and 0.38 g β-(4) (1.2% yield based on R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester). This corresponds to a crystallization yield of 60% (output α-(4)/[input α-(4)+β-(4)]) and an α-(4):β-(4) ratio of 26:1. Example 3B Using an Improved Work-Up Procedure for α-(4) and β-(4) To R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester (47.5 g, 84.2 wt % pure, 0.2 mol) was added nitromethane (26.0 g of a 51.7 wt % solution in methanol, 0.22 mol, 1.1 eq.) and the solution was cooled to 0° C. DBU (30.4 g, 0.2 mol, 1 eq.) was added dropwise during 30 min at 0-20° C. and the funnel was rinsed with methanol (4 g). The reaction mixture was heated up to 20° C., stirred for another 18 h at that temperature and cooled down to 0° C. Subsequently, NaOMe (40 g of a 29.6 wt % solution in methanol, 0.22 mol, 1.1 eq.) was added dropwise during 20 min at 0° C. and the resulting solution was stirred for 1 h at 0° C. Then, the mixture was quenched into a solution of H2SO4 (72 g, 96 Wt %, 0.7 mol, 3.5 eq.) in methanol (72 g) at 0-5° C. by dropwise addition during 3 h under vigorous stirring. The reaction mixture was stirred for another 2 h at 0-5° C. and subsequently quenched into a stirred slurry of KHCO3 (99 g) in water (200 mL) at 0-5° C. by dropwise addition during 1 h. The final pH was 4.1. After heating up to 20° C., the salts were removed by filtration and washed with ethyl acetate (500 mL). The aqueous mother liquor of the filtration (454 g) was concentrated in vacuo at 35° C. to remove the methanol until a final weight of 272 g and extracted with ethyl acetate (6×150 mL; first portions with the wash liquor of the salts filtration, then with fresh). The combined organic phases were concentrated in vacuo at 40-50° C. giving 40.4 g of a solid which, according to GC, contained 14.5 g α-(4) and 3.4 g β-(4) corresponding to a total yield of 57% based on R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester and an α-(4):β-(4) ratio of 4.3:1. The crude solid product was dissolved in ethyl acetate (300 mL) and the solution was washed with a mixture of saturated aqueous NaCl solution (25 mL) and water (10 mL). The organic layer which, according to GC, contained 14.1 g α-(4) and 3.4 g β-(4), was concentrated in vacuo to 42.4 g of a dreggy solid. To 38 g of this crude product was added isopropanol (62 g) and the solid was dissolved by heating to 60° C. The resulting solution was cooled to 50° C., seeded, and cooled further to 0° C. during 2 h which resulted in L crystallization of α-(4). The solids were isolated by filtration, washed with isopropanol (2×20 mL, 0° C.) and dried on the air giving 12.9 g off-white crystalline product which, according to GC, contained 12.2 g α-(4). This corresponds to 39% yield based on R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester) and a crystallization yield of 78% (output α-(4)/[input α-(4)+β-(4)]). No β-(4) could be detected. Example 4 Preparation of pure α-(4) from R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester by crystallization of α-(4), epimerization of β-(4) and second crystallization of α-(4) To R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester (42.3 g, 94.6 Wt/O pure, 0.2 mol) was added nitromethane (26.0 g of a 51.7 wt % solution in methanol, 0.22 mmol, 1.1 eq.) and the solution was cooled to 0° C. Subsequently, DBU (30.4 g, 0.2 mmol, 1 eq.) was added dropwise during 30 min at 0-20° C. and the reaction mixture was heated up to 20° C. and stirred for another 18 h at that temperature. The resulting reaction mixture was cooled to 0° C. and NaOMe (40 g of a 29.6 wt % solution in methanol, 0.22 mol, 1.1 eq.) was added dropwise at 0° C. The resulting solution was stirred for 1 h at 0° C. and quenched into a solution of H2SO4 (72 g, 96 wt %, 0.7 mol, 3.5 eq.) in methanol (72 g) at 0-5° C. by dropwise addition during 1% h under vigorous stirring. The reaction mixture was stirred for 2 h at 0-5° C. and then quenched into a stirred slurry of NaHCO3 (100 g), water (400 mL) and ethyl acetate (300 mL) at 0-5° C. by dropwise addition during 1 h. NaHCO3 (40 g) was portionwise added to keep the pH above 3.5. The salts were removed by filtration at 0-5° C. and washed with ethyl acetate (300 mL). After phase separation the aqueous phase was extracted with ethyl acetate (300 mL of wash liquor, 3×150 mL fresh). The combined organic phases were concentrated in vacuo, ethyl acetate (200 mL) was added and the mixture concentrated in vacuo once more giving 33.2 g of a semi-solid which, according to quantitative 1H NMR analysis contained 13.5 g α-(4) and 4.0 g D-(4) corresponding to a total yield based on R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester of 53% and an α-(4):β-(4) ratio of 3.5:1. The crude product was dissolved in isopropanol (70 g) at 60° C. The resulting solution was cooled to 50° C., seeded and cooled further to 0° C. resulting in crystallization of α-(4) which was isolated by filtration, washed with cold (0° C.) isopropanol (2×15 mL) and dried on the air. This gave 12.3 g of α-(4) which, according to quantitative 1H NMR analysis, was 97.1 wt % pure and contained no β-(4). This corresponds to a (first crop) yield of 38% based on R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester and a crystallization yield of 68% (output α-(4)/[input α-(4)+β-(4)]). The combined mother and wash liquors of the first crystallization (108 g, containing 4.0 g β-(4) and 1.2 g α-(4)) were concentrated in vacuo to 17.9 g of a liquid. Subsequently, methanol (9.05 g) and MeSO3H (0.91 g, 0.29 eq.) were added and the mixture was heated up to reflux. After 2 h of reflux the epimerization reaction was complete (α-(4):β-(4) ratio>3). After cooling to 20° C., triethyl amine (0.96 g, 1 eq. based on MeSO3H) was added and the mixture was concentrated in vacuo to 18.7 g of a viscous residue. The residue was redissolved in isopropanol (13.9 g) at 50° C. After cooling to 45° C. the mixture was seeded and cooled down to 0° C. resulting in crystallization of α-(4) which was isolated by filtration, washed with cold (0° C.) isopropanol (2×6 mL) and dried on the air. This gave 2.24 g α-(4) which, according to quantitative 1H NMR analysis, was 95.3 wt % pure and contained no β-(4). This corresponds to a (second crop) yield of 6% based on R-3-(2,2-dihethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester and a crystallization yield of 43% (output α-(4)/[input α-(4)+β-(4)] after the epimerization). Thus, the total α-(4) yield (crop 1 and 2) based on R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester was 44%. Example 5 Crystallization of α-(4) Starting from Crude Mixtures of α-(4) and β-(4) from Other Solvents than Isopropanol Example 5A: From Tert-Butanol A crude mixture (6.5 g) of α-(4) and β-(4) as obtained in Example 2A (containing 3.37 g of α-(4)+β-(4) in a ratio of 3.1:1) was dissolved in tert-butanol (16 g) at 72° C. Cooling to 55° C., seeding and further cooling to 25° C. resulted in the crystallization of α-(4) which was isolated by filtration, washed with isopropanol (5 mL, 20° C.) and dried in vacuo. This gave α-(4) (1.85 g) which, according to quantitative 1H NMR analysis, consisted of 82.9 wt % pure α-(4) corresponding to a crystallization yield of 46% ([output α-(4)+β-(4)]/[input α-(4)+β-(4)]) with an α-(4):β-(4) ratio of 30:1. Example 5B From Tert-Amylalcohol A crude mixture (7.25 g) of α-(4) and β-(4) (containing 3.44 g of α-(4)+β-(4) in a ratio of 2.9:1) was dissolved in tert-amylalcohol (15.7 g) at 70° C. Cooling to 60° C., seeding and further cooling to 40° C. did not result in crystallization. After seeding once more at 40° C. the solution was further cooled and crystallization of α-(4) started at 27° C. The mixture was further cooled down to 2° C. and the crystals of α-(4) were isolated by filtration, washed with tert-amylalcohol (7.5 mL, 20° C.) and dried in vacuo. This gave 2.35 g of an off-white product which, according to quantitative 1H NMR analysis, consisted of 1.91 g α-(4) and 0.11 g β-(4) corresponding to a crystallization yield of 59% ([output α-(4)+β-(4)]/[input α-(4)+β-(4)]) and an α-(4):β-(4) ratio of 18:1. Example 6 Crystallization of Pure α-(4) from a Mixture of α-(4) and β-(4) with Simultaneous Epimerization of β-(4) A solution of light-brown α-(4) (5.0 g, 96.6 wt % pure, 30.6 mmol, containing no β-(4)) and MeSO3H (0.3 g, 0.1 eq.) in methanol (200 mL) was stirred at 20° C. for 92 h resulting in epitnerization to an α-(4):β-(4) ratio of 3.6:1. The reaction mixture was subsequently concentrated in vacuo (20 mbar; 45° C.) to give 5.2 g of a sticky solid. This was taken up in methanol (50 mL) and concentrated once more in vacuo (20 mbar; 50° C.) to give 5.1 g of a dry light-brown solid which, according to quantitative 1H NMR analysis, contained α-(4) in 90 wt % purity (4.6 g, 29 mmol). No β-(4) was detected. Thus, nearly all (96%) initial α-(4) had been recovered. Example 7 Preparation of pure α-(4) from Freshly Prepared S-2,3-O-isopropylidene-glyceraldehyde using an improved procedure and crystallization of α-(4), epimerization of β-(4) and a second crystallization of α-(4) To 175 g of the E-R-3-(2,2-diethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester as prepared in Example 1 (78 wt % o pure, 136.5 g, 0.68 mol) was added nitromethane (88.6 g of a 51.7 wt % solution in methanol, 0.75 mol, 1.1 eq.) and the solution was cooled to 10° C. Subsequently, DBU (103.4 g, 0.68 mol, 1 eq.) was added dropwise during 35 min at 10-21° C. and the fuel was rinsed with methanol (7 g). After stirring for 18 h at 20° C. the resulting dark-red solution was cooled to 0° C. and NaOMe (134.6 g of a 30 wt % solution in methanol, 0.748 mol, 1.1 eq.) was added dropwise during 35 min at 0° C. and the funnel was rinsed with methanol (10 g). After 30 min stirring at 0° C. the reaction mixture was quenched into a solution of H2SO4 (243 g, 96 wt %, 2.38 mol, 3.5 eq.) in methanol (243 g) at 0-5° C. by dropwise addition during 3 h under vigorous stirring and the funnel was rinsed with methanol (2×15 g). After 2 h stirring at 0-2° C. the reaction mixture was quenched into a stirred slurry of KHCO3 (353 g) in water (680 mL) at 0-6° C. by dropwise addition during 1 h. The pH was 7 at the end of the quench and was adjusted to 4.1 with H2SO4 (96 wt %) at 0° C. After heating up to 20° C. the salts were removed by filtration and washed with ethyl acetate (3×375 mL). The wash liquor was used later on in the extractions. The mother liquor of the filtration (1380 g), according to GC, contained 3.08 wt % α-(4) and 0.82 wt % β-(4) (corresponding to a total yield of 50% based on E-R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester and an α-(4):β-(4) ratio of 3.75:1) was concentrated in vacuo to remove the methanol. To the resulting residue (760 g) water (80 g) was added and the pH was adjusted to 4.1 with H2SO4 (96 wt %). The resulting aqueous solution was extracted with ethyl acetate (700 mL, 4×500 mL). The combined organic phases were concentrated in vacuo at 35-40° C. to 181 g of a residue. The volatiles were coevaporated 3× with isopropanol (2×140 g and 90 g) giving a residue (146 g) consisting of a crude mixture of α-(4) and β-(4). The crude mixture (146 g) was dissolved in isopropanol (202 g) at 70° C. Insoluble material was removed by filtration and washed with isopropanol (5 mL); the weight after drying was 0.33 g. The filtrate (346 g) was cooled to 50° C. resulting in spontaneous crystallization of α-(4). The slurry was further cooled to 1° C. during 4 h and the crystals were isolated by filtration, washed with isopropanol (2×100 mL, 0° C.) and dried in vacuo for 17 h at 35° C. giving an off-white crystalline product (44.2 g). According to quantitative GC it consisted of 89.0 wt % α-(4) and 1.0 wt % β-(4) corresponding to a total yield of 37% based on E-R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester and an α-(4):β-(4) ratio of 89:1. The mother liquor and wash liquors of the first α-(4) crystallization (totally 374 g) were concentrated in vacuo to 90.8 g, methanol (1.20 mL) was added and the resulting mixture concentrated to 83 g. Methanol (120 mL) was added once more and the mixture concentrated to 83 g. To the residue was added methanol (45 g) and MeSO3H (2.66 g, 0.0277 mol, 0.2 eq. based on total α-(4)+β-(4) present in the mother liquor and wash liquors) and the solution was heated up to reflux. After 1 h at reflux (60-65° C.) GC indicated that the epimerization was complete (the α-(4):β-(4) ratio was 3.1:1) and the solution was cooled to 33° C., Neutralized with triethyl amine (2.94 g, 1.05 eq. based on MeSO3H) and concentrated in vacuo. To the resulting residue was added isopropanol (120 mL) and the mixture was concentrated in vacuo to give 88 g of a residue. The residue was dissolved in isopropanol (37 g) at 47° C. The resulting solution was cooled down to 2° C. during 2.5 h; crystallization started spontaneously at 30° C. The crystalline product was isolated by filtration, washed with isopropanol (3×20 mL, 0° C.) and dried in vacuo (17 h at 35° C.) to give 10.1 g of a white crystalline product which according to GC consisted of 96.4 wt % α-(4) and 0.065 wt % β-(4), corresponding with a total yield based on E-R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester of 9% and an α-(4):1β-(4) ratio of >1000:1. Thus, the total yield of the first and second crop of α-(4) based on E-R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester was 46%. Example 8 Preparation of pure (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol from α-(4) intermediate The procedure described in WO03/022853, Example IV, last step, was followed. Example 9 Preparation of pure α-(4) from R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester by direct crystallization of α-(4) from a crude mixture of β-(4) and α-(4) and simultaneous epimerization of β-(4) to α-(4) To R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester (399.5 g, 75.1 wt % pure, 1.5 mol) was added nitromethane (915.0 g of a 11 wt % solution in methanol, 1.65 mol, 1.1 eq.) and the solution was cooled to 0° C. Subsequently, DBU (233.3 g, 1.5 mol, 1 eq.) was added dropwise during 50 min at 0-5° C. and the reaction mixture was heated up to 20° C. and stirred for another 16 h at that temperature. The resulting reaction mixture was cooled to 0° C. and NaOMe (594.0 g of a 15 wt % solution in methanol, 1.65 mol, 1.1 eq.) was added dropwise during 50 min at 0° C. The resulting solution was stirred for 1 h at 0° C. and quenched into a solution of H2SO4 (368 g, 96 wt %, 3.6 mol, 2.4 eq.) in methanol (370 g) at 0-5° C. by dropwise addition during 3 h under vigorous stirring. The reaction mixture was stirred for 2 h at 0-5° C. and then quenched into a stirred slurry of KHCO3 (457.6 g), in water (870 mL) at 0-5° C. by dropwise addition during 1 h. KHCO3 was portionwise added to keep the pH above 3.5. The formed salts were removed by filtration at 0-5° C. and washed with methanol (530 mL). After concentration in vacuo of the combined filtrate and washing to approximately 1000 ml the aqueous phase was extracted with toluene (2×2100 mL, 3×1050 mL). The combined organic phases were concentrated in vacuo, giving 202.9 g of a semi-solid Subsequently, methanol (42.6 g) and MeSO3H (6.06 g, 0.04 eq.) were added and the mixture was heated up to 50° C. After 2 h of stirring at this temperature the mixture was cooled to 20° C. and stirring was continued for an additional 12 h. After cooling to −5° C., triethyl amine (6.60 g, 1.1 eq. based on MeSO3H) was added and the mixture was stirred for another 2 h. The crystalline α-(4) which was isolated by filtration, washed with cold (−5° C.) isopropanol (3×70 mL) and dried on the air. This gave 120.0 g α-(4) which, according to quantitative GC analysis, was 99.0 wt % pure and contained 0.09 area % of β-(4). This corresponds to a yield of 51% based on R-3-(2,2-dimethyl-[1,3]dioxolan-4-yl)-acrylic acid ethylester.

<SOH> SUMMARY <EOH>The present invention provides an improved Wittig process and the use of (3aR,4S,6aS)4-methoxy-tetrahydro-furo[3,4-b]furan-2-one as an intermediate, more in particular in crystalline form, in the preparation of diastereomerically pure (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol, which is suitable for industrial scaling up. The present invention provides a novel alkoxy-acetal epimerization of compound of formula β-(4) to the compound of formula α-(4) which significantly contributes into a cost-effective process for the preparation of diastereomerically pure (3R,3aS,6aR) hexahydro-furo[2,3-b]furan-3-ol. The present invention provides furthermore a simultaneous crystallization and epimerization for the isolation of diastereomerically pure (3aR,4S,6aS)4-methoxy-tetrahydro-furo[3,4-b]furan-2-one. Another embodiment of the invention provides with a method that allows the production of (3R,3aS,6aR)hexahydro-furo[2,3-b]furan-3-ol in a yield higher than for the methods described in the state of the art. Another object of the present invention is to provide with crystallizable and highly pure intermediate compounds, which are useful in the synthesis of diastereomerically pure (3R,3aS,6aR)hexahydro-furo[2,3-]furan-3-ol. detailed-description description="Detailed Description" end="lead"?

20060929

20090929

20070906

70225.0

C07D49302

CHANDRAKUMAR, NIZAL S

METHODS FOR THE PREPARATION OF (3R,3AS,6AR) HEXAHYDRO-FURO[2,3-B]FURAN-3-OL

UNDISCOUNTED

ACCEPTED

C07D

ACCEPTED

Fail-Safe Circuit For Gas Valves

The invention relates to a fail-safe circuit for gas valves. According to the invention, the fail-safe circuit (10) comprises at least one input (11) that can be connected to a regulator device and at least one output (12, 13) that can be connected to a gas valve. The fail-safe circuit (10) only supplies an output voltage that is required to open the gas valve to the output(s) (12, 13) if an input signal containing at least two different, successive frequency signals is applied by the regulator device to an input (11) of the fail-safe circuit.

1. A fail-safe circuit for piezo-operated gas valves, the fail-safe circuit comprising at least one input that can be connected to a control device and at least one output that can be connected to a gas valve, where the fail-safe circuit only supplies an output voltage to open a gas valve to the at least one output if an input signal containing at least two different successive frequency signals is provided by the control device at an input of the fail-safe circuit. 2. The fail-safe circuit of claim 1 comprising a charging circuit, which has at least one capacitor, where the charging circuit charges the at least one capacitor in the charging circuit when a first frequency signal is applied or is present in the input signal. 3. The fail-safe circuit of claim 2, wherein the charging circuit charges the at least one capacitor of the same only when the first frequency signal is present in the input signal. 4. The fail-safe circuit of claim 3, wherein the charging circuit does not charge the at least one capacitor in the charging circuit when a second frequency signal is applied or is present in the input signal, the second frequency signal having a lower frequency than the first frequency signal. 5. The fail-safe circuit of claim 4, wherein the at least one capacitor in the charging circuit discharges when the second frequency signal is applied or is present in the input signal. 6. The fail-safe circuit of claim 5 comprising a voltage transformer circuit, which produces an output voltage to open the gas valve from a supply voltage when the second frequency signal is applied or is present in the input signal. 7. The fail-safe circuit of claim 6, wherein the voltage transformer circuit has at least one capacitor, which charges when the second frequency signal is present in the input signal. 8. The fail-safe circuit of claim 7, wherein the at least one capacitor of the voltage transformer circuit continues to provide an output voltage to keep the gas valve open for a period of time when the first frequency signal is present in the input signal. 9. The fail-safe circuit of claims 6, wherein the voltage transformer circuit has a transistor having a base that is connected via a resistor to the capacitor of the charging circuit, where the transistor of the voltage transformer circuit only conducts if the capacitor of the charging circuit discharges when the second frequency signal is applied in the input signal. 10. The fail-safe circuit of claim 1, wherein the first frequency signal has a frequency of about 500 kHz and the second frequency signal has a frequency of about 10 kHz, and where the two frequency signals are applied successively in the input signal in such a way that a time period of about 30 milliseconds with the first frequency signal of about 500 kHz is respectively followed by a time period of about 100 milliseconds with the second frequency signal of about 10 kHz. 11. The fail-safe circuit of claim 1, wherein the first frequency signal and the second frequency signal are applied successively in the input signal in such a way that a first time period with the first frequency signal is respectively followed by a second time period with the second frequency signal. 12. A fail-safe circuit for gas valves, the fail-safe circuit comprising: at least one input that can be connected to a gas valve controller; at least one output that can be connected to a control input for a gas valve; and the fail-safe circuit configured to only supply an output signal to open the gas valve via the at least one output of the fail safe circuit if/when the gas valve controller provides an input signal having at least two different frequency signals to the at least one input of the fail-safe circuit. 13. The fail-safe circuit of claim 12 wherein the fail-safe circuit is configured to only supply an output signal to open the gas valve via the at least one output of the fail safe circuit when the gas valve controller provides an input signal that includes a first frequency signal that is coordinated in time with a second frequency signal. 14. The fail-safe circuit of claim 12 wherein the fail-safe circuit is configured to only supply an output signal to open the gas valve via the at least one output of the fail safe circuit if/when the gas valve controller provides an input signal that includes a first frequency signal for a first period of time followed by a second frequency signal for a second period of time. 15. The fail-safe circuit of claim 14 wherein the fail-safe circuit is configured to only supply an output signal to open the gas valve via the at least one output of the fail safe circuit if/when the first frequency signal is not supplied during the second period of time, and the second frequency signal is not supplied during the first period of time. 16. A method for controlling a gas valve, the method comprising the steps of: determining if a gas valve controller is currently providing a valid gas valve control signal; operating the gas valve in accordance with the gas valve control signal if the determining step determines that the gas valve controller is currently providing a valid gas valve control signal; and closing the gas valve if the determining step determines that the gas valve controller is not currently providing a valid gas valve control signal. 17. The method of claim 16 wherein the determining step includes determining if the gas valve controller is providing an input signal that includes a first frequency signal for a first period of time followed by a second frequency signal for a second period of time. 18. The method of claim of claim 17 wherein the determining step further determines if the first frequency signal is or is not supplied during the second period of time, and the second frequency signal is or is not supplied during the first period of time. 19. The method of claim 17 further comprising the steps of: charging a capacitor of a charging circuit during the first period of time when the input signal includes the first frequency signal; charging a capacitor of a transformer circuit during the second period of time when the input signal includes the second frequency signal, wherein a voltage across the capacitor of the transformer circuit opens the gas valve. 20. The method of claim 19 further comprising the steps of: not charging the capacitor of the charging circuit during the second period of time, and using a voltage across the capacitor of the charging circuit to activate the transformer circuit during the second period of time.

This application claims priority to PCT/EP2005/002855, filed on Mar. 17, 2005, which claims priority to DE102004016764.8 filed on Apr. 1, 2004. TECHNICAL FIELD The invention relates to a fail-safe circuit for gas valves. BACKGROUND Control devices for gas valves must be fail-safe. If the state of the control device is undefined, then it must be guaranteed that in this undefined state a gas valve controlled by the control device does not open. If, for example, a microprocessor is used as the control device for gas valves, then the use of a fail-safe circuit may help ensure that the whole arrangement is fail-safe. Recently, piezo-operated gas valves have been used, particularly in low-voltage applications such as water heaters without a mains connection. The piezo-operated gas valves are often controlled by a control device in the form of a microprocessor. In such low-voltage applications, the supply voltage is often approximately 3 volts, which can be provided by a battery. However, a voltage of typically at least 150 volts is required to open the piezo-operated gas valves. Accordingly, a fail-safe circuit is often desirable for low-voltage applications of this kind, which, on the one hand, provides an output voltage of at least 150 volts to open the piezo-operated gas valves from a low supply voltage of approximately 3 volts, and, on the other, only generates the output voltage required to open the piezo-operated gas valves if the control device, often in the form of a microprocessor, is in a defined state to open the gas valves. SUMMARY According to one illustrative embodiment the present invention, a fail-safe circuit includes at least one input that can be connected to a control device and at least one output that can be connected to a gas valve, where the fail-safe circuit only supplies an output voltage that is required to open a gas valve to the, or to each output, if an input signal containing at least two different, successive frequency signals is applied by the control device to an input of the fail-safe circuit. In some cases, a fail-safe circuit is created for gas valves, in particular for piezo-operated gas valves, which, on the one hand, is able to provide an output voltage of more than 150 volts that is required to open piezo-operated gas valves from a supply voltage of only approximately 3 volts, and, on the other, only provides this output voltage required to open the piezo-operated gas valves if the control device is in a defined state to open the gas valves. One illustrative fail-safe circuit may be characterized by a simple design and can be implemented cost-effectively. According to one illustrative embodiment, the fail-safe circuit may include a charging circuit and a voltage transformer circuit, but this is not required. The charging circuit may have at least one capacitor, where the charging circuit charges the one or more capacitor in the charging circuit when a first frequency signal is applied or is present in the input signal. On the other hand, when a second frequency signal is applied or is present, the one or more capacitors in the charging circuit discharge. In some cases, the voltage transformer circuit produces an output voltage that is required to open the gas valve from a supply voltage when the second frequency signal is applied or is present in the input signal. The voltage transformer circuit may have at least one capacitor, which charges when the second frequency signal is present in the input signal, and which discharges when the first frequency signal is present in the input signal, and hence maintains the output voltage required to open the gas valve more or less unchanged for a period of time. BRIEF DESCRIPTION The invention may be more completely understood in consideration of the following detailed description of an illustrative embodiment of the present invention in connection with the accompanying drawings, without being restricted to this or other illustrative embodiment, in which: FIG. 1 shows a circuit diagram of a fail-safe circuit for gas valves according to one illustrative embodiment of the present invention. DESCRIPTION An illustrative embodiment of the present invention is described in greater detail below with reference to FIG. 1. FIG. 1 shows a fail-safe circuit 10 for gas valves according to one illustrative embodiment, in particular for low-voltage applications. Possible examples of such low-voltage applications are water heaters without a mains connection in which piezo-operated gas valves are used. In such low voltage applications, a supply voltage is typically provided from a battery or from a generator integrated within the water circulation, the supply voltage in such applications is often about 3 volts. In FIG. 1 the supply voltage is identified with VBAT. In the illustrative embodiment of FIG. 1, the fail-safe circuit 10 has an input to which a control device sometimes in the form of a microprocessor can be connected, and two outputs 12 and 13, from which a supply voltage +/− VOUT is output for a gas valve. Depending on the signal from the control device, which is applied to the input 11 of the illustrative fail-safe circuit 10 of FIG. 1, the circuit may generate the output voltage VOUT that is necessary to open the gas valve using the supply voltage VBAT, which is approximately 3 volts, namely only when an input signal containing at least two different successive frequency signals is supplied by the control device to the input 11 of the fail-safe circuit 10. The illustrative fail-safe circuit 10 of FIG. 1 has a charging circuit 14 and a voltage transformer circuit 15. The charging circuit 14 and the voltage transformer circuit 15 contain the components enclosed by chain-dotted lines in FIG. 1. The charging circuit 14 of the illustrative fail-safe circuit 10 includes a capacitor 16, where two diodes 17 and 18 are connected in parallel with the capacitor 16. A resistor 19, which is connected to the input 11 of the fail-safe circuit 10 via a capacitor 20, is connected between the two diodes 17 and 18. As can be seen in the illustrative embodiment of FIG. 1, a transistor 22 is connected to the input 11 of the fail-safe circuit 10 via a resistor 21, the transistor 22 being designed as a bipolar transistor, namely as an NPN transistor in the illustrative embodiment. The base of the transistor 22 is connected to the input 11 of the fail-safe circuit 10 by means of the resistor 21. Connected to the capacitor 16 of the charging circuit 14 is a further resistor 23, which in turn is linked to the collector of the transistor 22 and the base of a transistor 24 of the voltage transformer circuit 15. The transistor 24 is in turn designed as a bipolar transistor, namely as an NPN transistor in the illustrative embodiment. In the illustrative embodiment of FIG. 1, the emitters of the two transistors 22 and 24 are connected together. As well as the transistor 24 already mentioned, the base of which is connected on the one hand to the collector of the transistor 22 and, on the other, by means of the resistor 23 to the capacitor 16 of the charging circuit 14, the voltage transformer circuit 15 furthermore contains a comparator 25, a coil 26, a diode 27, a capacitor 28, a resistor 29 and a further transistor 30. The transistor 30 is designed as a field effect transistor or a MOSFET transistor in the illustrative embodiment. As can be seen from FIG. 1, the coil 26 is connected on the one hand to the supply voltage VBAT and, on the other, to the so-called drain of the transistor 30, which is designed as a self-blocking field effect transistor in the illustrative embodiment. An anode of the diode 27 is connected between the coil 26 and the drain of the MOSFET transistor 30, whereas the cathode of the diode 27 is connected to the output 12. The source of the MOSFET transistor 30 is shown connected to the output 13, while the capacitor 28 of the voltage transformer circuit 15 is shown connected between the outputs 12 and 13 of the fail-safe circuit 10. As can also be seen from FIG. 1, the output of the comparator 25 connects to the gate of the MOSFET transistor 30 while the input of the same is connected to the collector of the bipolar transistor 25. Furthermore, the collector of the transistor 24 is connected by means of the resistor 29 to the coil 26 and thus to the supply voltage VBAT. As already mentioned, the fail-safe circuit 10 may only generate an output voltage of over 150 volts that is required to open the gas valve at the outputs 12, 13 if a signal containing at least two different successive frequency signals is provided by the control device at the input 11 of the fail-safe circuit 10. In this case, a defined operating state of the control device for opening the gas valve exists. In the illustrative embodiment, the input signal may contain two frequency signals, namely a first frequency signal with a frequency of about 500 kHz and a second frequency signal with a frequency of about 10 kHz, which are present or are applied successively in the signal provided by the control device in such a way that a time period of about 30 milliseconds with the first frequency signal of about 500 kHz is respectively followed by a time period of about 100 milliseconds with the second frequency signal of about 10 kHz. The illustrative fail-safe circuit 10 of FIG. 1 may work in such a way that when the first frequency signal of about 500 kHz is applied or is present at input 11, the charging circuit 14 charges the capacitor 16 of the same. While the second frequency signal of about 10 kHz is applied to the input 11, the capacitor 16 of the charging circuit is not charged but rather a discharge of the capacitor 16 takes place via the resistor 23 and the base of the transistor 24. The transistor 24 of the voltage transformer circuit 15 is then conductive if a current flows to its base due to the discharge of the capacitor 16. During the time period for which the first frequency signal of about 500 kHz is applied to the input 11, a high output voltage that is required to open the gas valve cannot be generated by the voltage transformer circuit 15 due to the high losses, in particular in the coil 26 and in the MOSFET transistor 30 of the voltage transformer circuit 15. Rather, this high output voltage is only generated when the second frequency signal with a frequency of about 10 kHz is applied to the input 11. When the second frequency signal of about 10 kHz is applied to the input 11, an output voltage VOUT of more than 150 volts that is required to open the piezo-operated gas valve is generated from the supply voltage VBAT by the voltage transformer circuit 15, and the capacitor 28 of the voltage transformer circuit 15 is charged. If a time period of about 100 milliseconds, in which the second frequency signal with a frequency of about 10 kHz is applied, is followed by a time period of about 30 milliseconds with the first frequency signal with a frequency of about 500 kHz, then the capacitor 28 of the voltage transformer circuit 15 discharges and essentially maintains the output voltage of more than 150 volts that is required to open the gas valve. The capacitor 28 discharges via the high resistance of the gas valve during the time period in which the first frequency signal with the frequency of about 500 kHz is applied. The specific design of the circuit described above is incumbent upon the person skilled in the art addressed here. In the particularly preferred exemplary embodiment in which an output voltage VOUT of about 250 volts is to be provided for opening the gas valve from the supply voltage VBAT of about 3 volts, the capacitance of the capacitor 28 is preferably 1 μF, the capacitance of the capacitor 16 is about 10 μF and the capacitance of the capacitor 20 is about 220 pF. The resistance of the gas valve connected to the outputs 12 and 13 can be assumed to be 10 MΩ, the resistor 21 is preferably chosen to be 1 MΩ, the resistor 19 to be 1 kΩ and the resistor 29 to be 10 kΩ. The resistor 23 preferably has a value of 22 kΩ. The coil 26 preferably has an inductance of 1 mH. With these values, the discharge time of the capacitor 28 is about 10 seconds from which it immediately follows that an output voltage that is required to open the gas valve can also be provided at the outputs 12 and 13 during the time period of 30 milliseconds in which the first frequency signal of about 500 kHz is applied to the input 11. LIST OF REFERENCES 10 Fail-safe circuit 11 Input 12 Output 13 Output 14 Charging circuit 15 Voltage transformer circuit 16 Capacitor 17 Diode 18 Diode 19 Resistor 20 Capacitor 21 Resistor 22 Transistor 23 Resistor 24 Transistor 25 Comparator 26 Coil 27 Diode 28 Capacitor 29 Resistor 30 Transistor

<SOH> BACKGROUND <EOH>Control devices for gas valves must be fail-safe. If the state of the control device is undefined, then it must be guaranteed that in this undefined state a gas valve controlled by the control device does not open. If, for example, a microprocessor is used as the control device for gas valves, then the use of a fail-safe circuit may help ensure that the whole arrangement is fail-safe. Recently, piezo-operated gas valves have been used, particularly in low-voltage applications such as water heaters without a mains connection. The piezo-operated gas valves are often controlled by a control device in the form of a microprocessor. In such low-voltage applications, the supply voltage is often approximately 3 volts, which can be provided by a battery. However, a voltage of typically at least 150 volts is required to open the piezo-operated gas valves. Accordingly, a fail-safe circuit is often desirable for low-voltage applications of this kind, which, on the one hand, provides an output voltage of at least 150 volts to open the piezo-operated gas valves from a low supply voltage of approximately 3 volts, and, on the other, only generates the output voltage required to open the piezo-operated gas valves if the control device, often in the form of a microprocessor, is in a defined state to open the gas valves.

<SOH> SUMMARY <EOH>According to one illustrative embodiment the present invention, a fail-safe circuit includes at least one input that can be connected to a control device and at least one output that can be connected to a gas valve, where the fail-safe circuit only supplies an output voltage that is required to open a gas valve to the, or to each output, if an input signal containing at least two different, successive frequency signals is applied by the control device to an input of the fail-safe circuit. In some cases, a fail-safe circuit is created for gas valves, in particular for piezo-operated gas valves, which, on the one hand, is able to provide an output voltage of more than 150 volts that is required to open piezo-operated gas valves from a supply voltage of only approximately 3 volts, and, on the other, only provides this output voltage required to open the piezo-operated gas valves if the control device is in a defined state to open the gas valves. One illustrative fail-safe circuit may be characterized by a simple design and can be implemented cost-effectively. According to one illustrative embodiment, the fail-safe circuit may include a charging circuit and a voltage transformer circuit, but this is not required. The charging circuit may have at least one capacitor, where the charging circuit charges the one or more capacitor in the charging circuit when a first frequency signal is applied or is present in the input signal. On the other hand, when a second frequency signal is applied or is present, the one or more capacitors in the charging circuit discharge. In some cases, the voltage transformer circuit produces an output voltage that is required to open the gas valve from a supply voltage when the second frequency signal is applied or is present in the input signal. The voltage transformer circuit may have at least one capacitor, which charges when the second frequency signal is present in the input signal, and which discharges when the first frequency signal is present in the input signal, and hence maintains the output voltage required to open the gas valve more or less unchanged for a period of time.

20070626

20100928

20080221

79939.0

F16K3102

AMRANY, ADI

FAIL-SAFE CIRCUIT FOR GAS VALVES

UNDISCOUNTED

ACCEPTED

F16K

ACCEPTED

Projection Apparatus And Method For Pepper's Ghost Illusion

An image projection apparatus (100) comprises a projector (106), a frame (108), and a partially transparent screen (110). The frame (108) retains the screen (110) under tension, such that the screen (110) is inclined at an angle with respect to a plane of emission of light from the projector (106). The screen (110) has a front surface arranged such that light emitted from the projector (106) is reflected therefrom. The projector (106) projects an image such that light forming the image impinges upon the screen (11) such that a virtual image is created from light reflected from the screen (110), the virtual image appearing to be located behind the screen (110).

1. An image projection apparatus comprising a projector, a frame, a light source and an at least partially transparent screen: the frame being arranged to retain the screen under tension at a plurality of positions along at least one edge of said screen, such that the screen is inclined at an angle with respect to a plane of emission of light from the projector; the light source arranged to illuminate at least part of the apparatus, the light source being optionally located to the rear of the screen, along a top edge of the frame and/or along either side of a stage; the screen having a front surface arranged such that light emitted from the projector is reflected therefrom; and the projector being arranged to project an image such that light forming the image impinges upon the screen such that a virtual image is created from light reflected from the screen, the virtual image appearing to be located behind the screen. 2. The apparatus according to claim 1 wherein the screen is a foil and/or the screen is inclined at approximately 45° to the plane of emission of light from the projector. 3-4. (canceled) 5. The apparatus according to claim 1 wherein the screen comprises upper and lower edges and the screen is attached to the frame at the screen's upper and/or lower edges. 6. The apparatus according to claim 1 wherein the frame comprises first and second retention members each arranged to sandwich an edge region of the screen therebetween. 7. The apparatus according to claim 6 wherein at least one of the first and second retention members comprises an abrasive coating arranged to contact the screen. 8. The apparatus according to claim 6 wherein the first and second retention members comprise respective openings therethrough arranged to collocate with respective openings in the screen and at least one of the first and second retention members are each attached to tensioning straps. 9. The apparatus according to claim 8 wherein the openings are arranged to receive a fixing means so as to clamp the screen between the first and second retention members. 10. The apparatus according to claim 8 wherein the tensioning straps are attached to a truss arrangement or a fixed mounting point located in a permanent structure such as a wall, floor or ceiling and are adjustable such that the tension of the screen within the truss arrangement can be varied about the periphery of the screen. 11. The apparatus according to claim 10 wherein the retention members are substantially parallel to truss members comprising the truss arrangement. 12. The apparatus according to claim 1 which comprises a pigmented reflective member in an optical pathway between a lens of the projector and the screen. 13. The apparatus according to claim 12 which comprises an adjustably angled, mirrored surface in an optical pathway between the lens of the projector and the pigmented reflective member. 14-15. (canceled) 16. The apparatus according to claim 12 wherein the pigmented reflective member is inclined at an angle with respect to the plane of emission of light from the projector. 17. The apparatus according to claim 12 wherein the pigmented reflective member comprises a plurality of sections each of which has an independently variable angle of inclination with respect to the axis perpendicular to the plane of emission of light from the projector. 18. The apparatus according to claim 16 wherein the angle of inclination of the member with respect to the plane of emission of light from the projector is variable. 19-24. (canceled) 25. The apparatus according to claim 1 which comprises at least one non-emitting element in response to control from a processor, said non-emitting element optionally forming a mask arranged to produce an area upon the screen upon which the image is not projected. 26. (canceled) 27. A method of providing a frame and screen for an image projection apparatus having a projector, a frame, a light source and an at least partially transparent screen, the frame being arranged to retain the screen under tension at a plurality of positions along at least one edge of said screen, such that the screen is inclined at an angle with respect to a plane of emission of light from the projector; the light source arranged to illuminate at least part of the apparatus; the screen having a front surface arranged such that light emitted from the projector is reflected therefrom; and the projector being arranged to project an image such that light forming the image impinges upon the screen such that a virtual image is created from light reflected from the screen, the virtual image appearing to be located behind the screen; comprising the steps of: (i) resting a frame upon a number of elevation means; (ii) attaching leg sections to the frame; (iii) increasing the height of the elevation means; (iv) adding further leg sections; (vi) attaching a lower edge of a screen to a first retention member on a lower rear piece of the frame; (vii) raising an upper edge of the screen to adjacent an upper front section of the frame; and (viii) attaching the upper edge of the screen to a second retention member on the upper front section of the frame. 28-33. (canceled) 34. The method of claim 27 wherein the frame comprises first and second retention members each arranged to sandwich an edge region of the screen therebetween; and the openings are arranged to receive a fixing means so as to clamp the screen between the first and second retention members; further comprising securing the screen in position using respective fixing means passing through either or both of the respective retention members, and the screen, and respective locking means arranged to lock the respective fixing means in position. 35. The method of claim 34 comprising attaching tensioning means to either, or both, of the respective retention members. 36. The method of claim 35 comprising attaching the tensioning means adjacent at least some of the respective fixing means; and/or attaching the tensioning means associated with the retention member attached to the lower edge of the screen to a lower rear piece of the frame in step (vi); and/or attaching the tensioning means associated with the retention member attached to the upper edge of the screen to an upper front piece of the frame in step (viii); and/or providing the tensioning members in the form of ratchet straps; and/or tensioning each of the tensioning means such that the screen is flat and substantially wrinkle free. 37-42. (canceled) 43. A frame and screen constructed by the steps of: (i) resting a frame upon a number of elevation means; (ii) attaching leg sections to the frame; (iii) increasing the height of the elevation means; (iv) adding further leg sections; (vi) attaching a lower edge of a screen to a first retention member on a lower rear piece of the frame; (vii) raising an upper edge of the screen to adjacent an upper front section of the frame; and (viii) attaching the upper edge of the screen to a second retention member on the upper front section of the frame.

This invention relates to a projection apparatus and method. More particularly, but not exclusively, it relates to a projection apparatus arranged to project an image of an object upon an inclined, partially reflective, screen so as to give a false perception of depth and a method for constructing such an apparatus. The projection of an image upon a partially reflective screen such that is observable by a viewer positioned in front of the screen is known, the so-called “Peppers ghost” arrangement that is known form fairground shows. This has been applied to publicity and promotional displays where a presenter resides behind an inclined, partially reflective screen, typically a tensioned foil, onto which an image of, for example, a motor vehicle is projected, via at least one reflective surface, see for example EP 0799436. The location of the presenter behind the projected image has a number of inherent advantages over systems where the presenter stands in front of a screen, not least of which is that the presenter does not obscure the projected image when walking across the projected image. Additionally, the use of an inclined screen results in a viewer of the image perceiving the image as having depth rather than merely being a two dimensional image, for example where a motor vehicle is seen to rotate upon a turntable. However, current image projection apparatus' do have a number of problems associated with them, for example, mounting of the foil can prove difficult which in turn leads to uneven tensioning of the foil and wrinkles upon the foil, that impair the viewed quality of the image projected onto the foil. Also, in mounting the foil the foil must be laid out upon a clean dust free piece of cloth or plastic sheet, which is larger than the foil, in order to prevent particles adhering to the foil, such particles can scratch the surface of the foil and impair the viewed quality of the projected image or act as scattering centres from which projected light is incoherently scattered, thereby detracting from the viewed quality of the image as this scattered light does not contribute to the viewed image. Also, as the illusion of peppers ghost relies on the reflected image formed by light contrasting with its immediate surroundings and background. The stronger the reflected image, the more solid that reflected image looks, the more vibrant the colours will be, and the more visible the reflected image is to an audience. In circumstances where the presenter may be unable to control high levels of ambient light forward of the foil, e.g. from an auditorium at a trade show, the high level of ambient light results in significant levels of reflection of the ambient light from the screen detracting from the strength of the reflected image over the background. In these circumstances a bright projector (8000 lumens+) is desirable. However, the use of a bright projector results in unwanted light hitting the projection surface and reflecting through the foil to create a milky hue upon the stage and around the area where the reflected image appears. Another problem with current image projection apparatus is that projectors used with such apparatus are very powerful, typically 8,000 to 27,000 lumens and consequently project a significant amount of light into areas of an image where there is no object within the image. This is an inherent feature of projectors and results in low contrast ratios which leads to a milky hue spread over the part of the film where the projector is creating an image when the projector is switched on. The milky hue is clearly undesirable as it detracts from the viewer's perception that there is no screen present. The level of the milky hue relative to the brightness of the image is, at least partially, determined by the level of contrast ratio offered in the projector. The higher the contrast ratio, then the brighter the image can be relative to the brightness level of the milky hue. Even projectors with contrast rations as high as 3000:1 still emit a milky light hue when used in a “Pepper's Ghost” arrangement. A further problem associated with some projectors is the “keystone” effect, in which distorted, typically elongated, images (up and down) occur due to angled projection. This is of particular relevance where depth perception is of importance. The solution employed in modern, expensive projectors is to employ digital correction of keystone distortions. However, older, less-expensive or even some specialist High Definition projectors do not employ such digital keystone correction and are therefore difficult to configure for use with current image projection apparatus. High definition (HD) projectors do not offer keystone adjustment because when keystone correction is attempted in conjunction with the increased number of pixels about an image's edge causes the pixels about the edge of the image to appear ‘crunched’. Additionally, when processing moving images HD projectors compromise projector processing speed. When the processing power is used to carry out both keystone correction and motion processing the image is seen to jerk during movements, an effect known as “chokking”. In general, it can be said that the use of electronic keystone correction to alter a video image will result in the degradation of picture quality compared to an image which is not subject to such a process. Additionally, current systems do not allow for the projected image to apparently disappear and re-appear from behind a solid 3D object placed upon the stage, as the screen lies in front of the presenter and closest to the viewing audience. According to a first aspect of the present invention there is provided a image projection apparatus comprising a projector, a frame, and an at least partially transparent screen: the frame being arranged to retain the screen under tension, such that the screen is inclined at an angle with respect to a plane of emission of light from the projector; the screen having a front surface arranged such that light emitted from the projector is reflected thereform; and the projector being arranged to project an image such that light forming the image impinges upon the screen such that a virtual image is created from light reflected from the screen, the virtual image appearing to be located behind the screen. Such an apparatus is advantageous over present systems in that the screen need not be coated with an expensive, partially reflective coating, an angular dependence of reflectivity of transparent dielectric materials can be used to bring about partial reflectance of the projected image. Thus, this apparatus simplifies the manufacture of such systems and also reduces their production costs. Additionally, the use of a frame frees the screen from having to be fixed directly to a ceiling, or a floor, and therefore increases the utility of apparatus over the prior art systems. The screen may be a foil. The foil may be rolled about a cylinder when not in use. The screen may be inclined at approximately 45° to the plane of emission of light from the projector. The screen may comprise a partially reflective layer upon the front surface. The use of a foil screen reduces the weight of the apparatus, this allows ready transportation of the apparatus between sites. Rolling the foil onto a cylinder when not in use serves to protect the foil from damage during transportation and also allows ready transportation of the apparatus between sites. The use of a partially reflective screen can increase the degree of light reflected from the screen and can increase the audience perceived strength of the virtual image. The screen may be attached to the frame at the screen's upper and/or lower edges. The frame may comprise first and second retention members arranged to sandwich an edge region of the screen therebetween. At least one of the first and second retention members may comprise an abrasive coating, typically sandpaper, arranged to contact the screen. The first and second retention members may comprise respective openings therethrough that may be arranged to collocate with openings in respective jaws of clamping members attached to tensioning straps, the openings may be arranged to receive a fixing means so as to clamp the screen between the first and second retention members. The tensioning straps may be attached to a truss arrangement and may be adjustable such that the tension of the screen within the truss arrangement can be varied about the periphery of the screen. Preferably, the retention members are substantially parallel to truss members comprising the truss arrangement. The use of a variable tensioning arrangement allows wrinkles upon the screen to be minimised, and ideally eradicated to present a smooth surface for upon which the image can be projected. An abrasive surface upon at least one of the retention members increases the grip between the retention member and the screen thereby reducing the likelihood of the screen slipping when held by the retention member. The apparatus may comprise a pigmented reflective member in an optical pathway between the projector and the screen. The pigmented member may reflect only part of the visible spectrum of light, typically the pigmented member will appear grey or white to a viewer. It has been found that the use of a grey reflective member in the optical pathway between the projector and the screen reduces the outline of the reflective member upon the screen compared to when a white reflective member is used, and also reduces the level of the milky white hue associated with the projector emitting light where there is no image of an object to be projected. The pigmented reflective member may be inclined at an angle with respect to the plane of emission of light from the projector. The angle of inclination of the member with respect to the plane of emission of light from the projector may be variable. The member may comprise a plurality of sections each of which may have an independently variable angle of inclination with respect to the plane of emission of light from the projector. The inclination of the reflective member can compensate, at least partially and in some instances completely, for keystone effect. The variation of the angle of inclination or distance of the reflective member allows for a variation of the apparent depth and/or position of an object when projected upon the screen. This is because the virtual image appears as far behind the screen as the real image is in front of the screen. There may be a reflective device, typically a mirror, arranged to direct light projected from the projector on to the reflective member. Typically, the reflective device is mounted upon an upper part of the framework. The reflective member may be parallel, or substantially parallel, to the reflective device. In some embodiments the projector may be mounted upon an upper truss of the framework and may be aligned with the horizontal, typically light projected from the projector is directed on to the reflective device. Such an arrangement compliments the keystone correction achievable by the inclination of the screen and the reflective member and is particularly useful where an HD projector is used in order to compensate for the keystone effect without the use of the projector's processing power. The reflective member may comprise a mask corresponding to the apparent location of a prop in the screen to an audience. Typically, the mask will absorb light over at least a fraction of the visible spectrum and preferably the mask will be black. The mask may be arranged to produce an area upon the screen upon which the image is not projected. The mask may vary in extent and shape, for example by the use of a sliding element that is moved in and out of position upon the reflective member. The mask can be used to make the illusion of an article disappearing and reappearing behind a prop that is placed upon a stage, either behind or in front of the screen. The apparatus may comprise a light source arranged to selectively illuminate an area of stage comprising the prop. The light source may be a white light source Lighting the prop causes the prop to become more visible and better defined against the dark, typically black, background. This enhances the three dimensional effect of the projected image interacting with the prop. Also directing bright light upon the prop serves to reduce the contrast ratio of the projected image upon the prop, which typically remains slightly visible even when a mask is used in the prop's shadow upon the reflective member, thus enhancing the illusion of the projected image disappearing behind the prop. The apparatus may comprise a light source arranged to illuminate at least part of a stage. The light source may be located to the rear of the screen, typically along a top edge of the frame and/or along either side of the stage. The apparatus may comprise a plurality of light sources. The apparatus may comprise a lighting desk equipped with faders arranged to control the level of each light source, or selection means arranged to selectively control the supply of power to each light source. Such a light source is used in order that the colour and light levels of the area immediately surrounding the peppers ghost image, the stage background, can most closely match the colour of the projection surface background, excluding the area on both which is carrying the image. This, reduces the milky hue perceived by the audience. The use of a plurality of light sources increases the uniformity of lighting of the stage, in order to produce a similar effect to the way light emitted from a projector hits the projection screen. By controlling each light source separately the lighting levels upon the stage can be controlled to closely match the levels of light as dictated by the show performance, or the levels of unwanted light hitting the projection surface of the screen. The projector may comprise a standard projector, for example a JVC ML4000, or a Barco G5. Alternatively, the projector may comprise an LCD, or a television display. The display may comprise at least one element arranged to be non-emitting in response to control from a processor. The at least one element may form a mask arranged to produce an area upon the screen upon which the image is not projected. The mask may correspond to the shape and location of a prop upon stage. The prop may be three dimensional. According to a second aspect of the present invention there is provided a method of providing a projection apparatus comprising the steps of: (i) resting a frame upon a number of elevation means; (ii) attaching leg sections to the frame; (iii) increasing the height of the elevation means; (iv) adding further leg sections; (vi) attaching a lower edge of a screen to a lower rear piece of the frame; (vii) raising an upper edge of the screen to adjacent an upper front section of the frame; and (vii) attaching the upper edge of the screen to the upper front section of the frame. The method may comprise providing the elevation means in the form of a jack. The method may comprise providing the screen in the form of a film. The method may comprise removing a roll of screen film from a protective cylindrical casing. The method may comprise laying the screen upon a dust-free protective sheet. The method may comprise placing the lower edge of the screen between jaws of a first retention member and may further comprise securing the screen in position using a fixing means passing through the retention member and the screen and a locking means arranged to lock the fixing means being arranged to secure the locking means in position. The method may comprise providing the fixing means in the form of a bolt and the locking means in the form of a nut. The method may comprise attaching tensioning means to the retention member adjacent at least some of the fixing means. The method may comprise attaching the tensioning means to the lower rear piece of the frame. The method may comprise attaching a second retention member to an upper edge of the film screen, typically in the same manner as the first retention member is attached to the lower edge. The method may comprise attaching tensioning means to the second retention member. The method may comprise providing the tensioning members in the form of ratchet straps. The method may comprise attaching a rope to the second retention member and passing the rope over the upper frame and using the rope in step (vii) to raise the screen. The method may include tensioning each of the tensioning means such that the screen is flat and substantially wrinkle free. The method may include depending a projector from the upper frame. The method may include placing a pigmented reflective board between the screen and a front edge of the frame. The method may comprise reflecting light emitted by the projector from the board onto the screen. The method may comprise forming the frame form a truss work. According to a third aspect of the present invention there is provided a projection apparatus constructed according to the second aspect of the present invention. The invention will now be described, by way of example only, with reference to the accompanying drawings, in which: FIG. 1 is a schematic representation of a first embodiment of a projection apparatus according to at least an aspect of the present invention; FIG. 2 is a side view of a the projection apparatus of FIG. 1 showing a pigmented reflective member in first and second positions; FIG. 2a is a schematic representation of an alternative projection arrangement, suitable for use with the apparatus of FIGS. 1 and 2; FIG. 3 is a schematic representation of a second embodiment of a projection apparatus according to at least an aspect of the present invention; FIG. 4 is a perspective view of a screen clamping arrangement of FIGS. 1, 2 and 3; and FIG. 5 is a schematic view of a projection apparatus being constructed according to the second aspect of the present invention. Referring now to FIGS. 1, 2 and 4, a projection apparatus 100 comprises a box frame 102 formed of trusses 104, a projector 106, a support frame 108, a screen 110 held within the support frame 108 and a grey pigmented reflective board 112. The projector 106 depends from a front upper cross-piece truss 104a of the box frame 102. The board 112 lies below the projector 106 at the base of the box frame 102. The screen 110, is inclined at approximately 45° to the horizontal and the front edge of the screen 110 is proximate the front upper cross-piece truss 104a of the box frame 102 and the rear edge of the screen is proximate a stage 109 that lies to the rear of the box frame 102. The screen 110 is typically a polymeric foil, which can have a partially reflective coating upon a front face of the foil. The screen 110 is retained within the box frame 102 by means of tensioning straps 114 attached to the box frame 102, at the top and bottom edges of the screen 110. At a free end of each of the tensioning straps 114 there is pair of clamp jaws 116 which have respective openings 118,120 passing therethrough. The faces of the jaws 116 are optionally coated with an abrasive 121, such as sandpaper, in order to enhance the grip of the jaws 116 upon the screen 110. Edges of the screen 110 are placed between the jaws 116 and a bolt 122 is placed through the openings 118, 120 and passes through the screen 110. A nut 124 is threaded onto the bolt 122 and tightened to hold the screen 110 between the jaws 116. The tensioning straps 114 pass through the trusses 104 and are tightened using a friction locking buckle arrangement 128. Each of the tensioning straps 114 can be tightened or loosened individually so as to allow an even tension to be applied over the whole surface of the screen 110 thereby reducing, and ideally eliminating, the formation of wrinkles upon the screen 110 which reduce the quality of an image projected upon the screen 110. The reflective board 112 lies below the projector 106 adjacent to a lower front cross-piece truss 104b of the box frame 102. The projector 106 is directed such that light emitted by the projector 106 strikes the reflective board 112. The board 112 is inclined so that the light emitted by the projector 106 is reflected upwards from the board 112 onto the screen 110. The use of a grey, or otherwise coloured board 112 reduces the milky hue associated with light from the projector where there is no image to be projected. A fraction of the projected light striking the screen 110 is reflected from the front surface of the screen 110 where is can be viewed by an audience. A presenter upon the stage 109 behind the screen 110 can also be viewed by the audience but does not interfere with the viewing of the image by the audience. The board 112 is connected to a hinge arrangement 130 along a rear edge thereof. The hinge arrangement 130 allows the board 112 to be raised and lowered, typically be a hydraulic ramp 132 controlled by a computer 134, in order to compensate for the ‘keystone’ effect. Alternatively, the board 112 can be raised and lowered by the person pulling upon a string, or an electric motor to drive the board up and down. The raising and lowering of the board 112 also allows for the audience's perception of the positional depth upon the stage of an element of a projected image to be altered by varying the height of the element of the image upon the screen 110. It is envisaged that the board 112 may comprise a number of individual sections each of which may be raised an lowered individually in order to allow the perceived depth of an individual element of an image to be varied independently of other elements of the image. A non-reflective mask 136 in the shape of a prop 138, in this example a rock, is placed upon the board 112. The prop 138 is place upon the stage 109, typically behind the screen 110. The mask 136 is placed such that the board 112 is obscured in a region corresponding to where the prop 138 is located with respect to the screen 110. This arrangement of mask 136 and prop 138 results in an image, or part of the image, projected upon the screen 110 apparently disappearing as the image, or part of the image, passes over prop 138 and reappearing once the image, or part of the image has passed over the prop 138 as the mask 136 prevents light being reflected onto the region of the screen 110 corresponding to the location of the prop 138. The mask 136 can be variable in size and shape, for example by means of a sliding panel that is moved into location and varied in size according to the size of the prop 138. This also allows for the depth perception of props to be varied as their apparent effect upon variable depth image elements, as discussed hereinbefore, can be varied appropriately, for example a given size of rock will obscure proportionately more of a distant image than the same rock will of a near image. A light source 140 is mounted upon the box frame 102 and illuminates the prop 138 in order to reduce the effect of any residual light reflected from the board 112 onto the prop. Referring now to FIG. 2a, an alternative projection arrangement 200, suitable for use with the apparatus of FIGS. 1 and 2 with an additional truss, comprises the projector 106 depending from a truss 202 forward of the screen 110, an inclined mirror 204 of variable inclination depending from a second truss 206 forward of projector 110. The projector 106 projects an image on to the mirror 204 such that the image is projected on to the reflective board 112 and on to the screen 110. The mirror 204 is typically arranged to be perpendicular to the board 112, and in embodiments where the board 112 has a variable angle of inclination the mirror 204 will usually be arranged to track, synchronously, with any variation in the angle of inclination of the board 112. It will be appreciated that the term mirror is used herein to describe any reflective surface that reflects substantially all, typically in excess of 50% preferably in excess of 80%, light impinging upon it. Referring now to FIG. 3, a projection apparatus 300 is substantially similar to that of FIGS. 1 and 2 accordingly identical parts to those of FIGS. 1 and 2 are accorded similar reference numerals in the three hundred series. A projection screen 306 resides in front of the screen 310 adjacent the lower front cross-piece truss 304b. The projection screen 306 is typically a liquid crystal display (LCD) screen or a television screen. The projection screen 306 projects an image upwards onto the front surface of the screen 310. The use of a projection screen 306 removes the ‘keystone’ effect associated with conventional projectors. A mask 336 can be formed upon the screen by use of a computer 340 to control the projection screen 306 to black out the appropriate part of the projection screen 306 electronically. This removes the need for a physical mask to be produced. The computer 340 can be used to switch of areas of the projection screen 306 which do not contain part of an image to be projected, this reduces the milky white hue associated with such areas when using conventional projectors. Also, the use of a computer 340 to control the projection screen 306, together with image sizing in relation to image movement allows an image to be readily scaled and positioned upon the projection screen 306 to enhance an audience's perception of depth and movement of a projected image using known image processing techniques. Alternatively, the projection screen 306, or sections of the projection screen 306, can be raised and lowered under the control of the computer 340 in order to enhance the audience's perception of depth of the projected image. Referring now to FIG. 5, a box truss framework 500 comprises a square upper truss work 502 and leg trusses 504. In constructing the framework 500 the upper truss work 502 rests upon a number of jacks 506. First sections 508 of the leg trusses 504 that extend at right angles to the upper truss work 502 are added at the corners of the upper truss work 502. The height of the jacks 506 is increased to allow additional sections 510 of the leg trusses 504 to be added until the desired height of the box truss framework 500 is achieved. A cross-piece truss 512 is fixed to two of the leg trusses 504 such that it horizontally spans the gap therebetween at a height close to, and typically slightly below, the level of a stage floor 514. The leg trusses 504 spanned by the cross-piece truss 512 constitute the rear legs of the framework 500 and are located adjacent the front of the stage floor 514. A dust-free protective plastic sheet 515 is laid across the width of the stage floor 514 in front of the rear legs of the framework 500. A roll of screen film 518 is removed from a protective cylindrical casing 520 and is unwound across the width of the stage floor 514. The film 518 is placed upon the sheet 515 in order to prevent damage to the surface from dust particles or other sharp protrusions. A lower edge 522 of the film 518 is placed between jaws 524a,b of a retention member 526, each jaw 524a,b having opposed openings therethrough spaced at approximately 0.5 m intervals. Bolts 528 are placed through the openings, and through the film 518, and secured in position using respective nuts. Ratchet straps 532 are attached to the retention member 526 adjacent alternate bolts 528, having a spacing of approximately 1 m, and are then attached to the cross-piece truss 512. A second retention member 534 is attached to an upper edge 536 of the film 518 in a similar manner to how the retention member 526 is attached to the lower edge 522. Ratchet straps 538 are attached to the second retention member 534. A rope 540 is tied to the second retention member 534 and is passed over the upper truss work 502 opposite the cross-piece truss 512. The film raised into position using the rope 540 and the ratchet straps 538 are attached to the upper truss work 502. Both sets of ratchet straps 532, 538 are tightened individually until the screen film is tensioned such that the film 518 is flat and, ideally, free from wrinkles. A projector 542 is depended from the upper truss work 502 and a pigmented reflective board 544 is placed between the screen 518 and the front edge of the box truss framework 500 such that light emitted by the projector 542 is reflected from the board 544 onto the screen 518. The screen 518 reflects at least part of the light from a front surface thereof away from the stage and into an auditorium to be viewed by and audience. In order to prevent the audience observing the projection apparatus both side and front drapes 546 are used to screen the apparatus from the audience.

20060930

20110208

20070830

68839.0

G03B2100

HOWARD, RYAN D

PROJECTION APPARATUS AND METHOD FOR PEPPER'S GHOST ILLUSION

SMALL

ACCEPTED

G03B

ACCEPTED

Collision Warning System

A method of estimating a time to collision (TTC) of a vehicle with an object comprising: acquiring a plurality of images of the object; and determining a TTC from the images that is responsive to a relative velocity and relative acceleration between the vehicle and the object.

1. A method of estimating a time-to-collision (TTC) of a vehicle with an object comprising the step of: (a) acquiring a plurality of images of the object at known time intervals between the times at which the images of the plurality of images are acquired; and (b) determining the time-to-collision (TTC) solely from information derived from the images and the time intervals, wherein said determining the TTC is based on a relative velocity and relative acceleration between the vehicle and the object. 2. The method according to claim 1, further comprising the step of: (c) determining the relative velocity from the images and using the relative velocity to determine TTC. 3. The method according to claim 1, wherein said (b) determining the time-to-collision (TTC) includes determining a change in scale of an image of at least a portion of the object and using the change in scale for determining a function of the relative velocity. 4. The method, according to claim 1, further comprising the step of: (c) determining a function of the relative acceleration from the images and using said function of the relative acceleration to determine the TTC. 5. The method according to claim 4, wherein said (c) determining said function of the relative acceleration includes determining a time derivative of a function of the relative velocity. 6. The method according to claim 3, wherein said determining a change in scale includes determining a ratio between a dimension of the object in a first one of the images and the same dimension of the object in a second one of the images. 7. The method according to claim 6, wherein said determining a function of the relative velocity includes determining a function Tv=[1/(S−1)]ΔT where S is the ratio and ΔT is a time lapse between two images of the images. 8. The method according to claim 7, wherein a function of the relative acceleration is determined based on a time derivative T′v, of function Tv. 9. The method according to claim 8, wherein the TTC is determined responsive to a function of Tv and T′v. 10. The method according to claim 8, wherein TTC is determined responsive to the expression: TTC (t)=[Tv/C)][1−(1+2C)]1/2, where C=T′v+1. 11. The method according to claim 1, further comprising the step of: (c) determining whether the vehicle and the object are on a course that leads to a collision at the TTC. 12. A method according to claim 11, wherein said determining whether the vehicle and object are on a course that leads to a collision at the TTC includes: (i) determining respective motions of at least two features of the object relative to the vehicle from the images; and (ii) determining from the relative motions whether at TTC said at least two features straddle at least a part of the vehicle. 13. A system which performs the method steps of claim 1, for determining the time-to-collision (TTC) of the vehicle with the object, the system comprising: (a) at least one camera mounted in the vehicle and adapted for said acquiring of the images; and (b) a processor which determines the time-to-collision (TTC) solely from information derived from the images and the time intervals, based on the relative velocity and the relative acceleration between the vehicle and the object. 14. The system, according to claim 13 wherein the at least one camera is a single camera. 15. The system, according to claim 13, further comprising: (c) an alarm apparatus for alerting a driver of the vehicle to a possible collision with the object responsive to the TTC. 16. The system, according to claim 13, further comprising: (c) an alarm apparatus which alerts, based on the TTC, at least one person outside of the vehicle to a possible collision of the vehicle with the object. 17. The system, according to claim 13, wherein the at least one camera images an environment in front of the vehicle. 18. The system, according to claim 13, wherein the at least one camera images an environment in back of the vehicle. 19. The system, according to claim 13, wherein the at least one camera images an environment to a side of the vehicle. 20. A method of determining whether a vehicle and an object are on a collision course, the method comprising the steps of: (a) acquiring a plurality of images of the object from a position of the vehicle at each of a plurality of known times; (b) determining, from the images, respective motions of at least two features of the object relative to the vehicle; (c) determining from the images an estimate of a possible time to collision (TTC) of the vehicle and the object; and (d) determining from the relative motions whether at the TTC, the at least two features straddle at least a part of the vehicle, whereby the vehicle and object are on a collision course. 21. The method according to claim 20, wherein said (b) determining respective motions of the at least two features includes determining lateral motion of the features relative to the vehicle. 22. The method according to claim 20, wherein said (d) determining includes extrapolating lateral locations of the at least two features at TTC from the respective motions at the known times of said acquiring. 23. A method according to claim 20, wherein said (c) determining includes determining TTC solely from the images and time intervals between the known times of said acquiring of the images. 24. A system which performs the method steps of claim 20, for determining whether a vehicle and an object are on a collision course, the system comprising: (a) at least one camera mounted in the vehicle and adapted for said acquiring of the images; and (b) a processor which determines from the images, respective motions of at least two features of the object relative to the vehicle and from the images determines an estimate of a possible time to collision (TTC) of the vehicle and the object; and from the relative motions determines whether at the TTC, the first and second features straddle at least a part of the vehicle.

RELATED APPLICATIONS The present application claims the benefit under 35 USC 119(e) of U.S. provisional application 60/560,049 filed on Apr. 8, 2004, the disclosure of which is incorporated herein by reference. FIELD OF THE INVENTION The invention relates to methods and apparatus for estimating a time to collision between a vehicle and an obstacle. BACKGROUND OF THE INVENTION Automotive accidents are a major cause of loss of life and dissipation of resources in substantially all societies in which automotive transportation is common. It is estimated that over 10,000,000 people are injured in traffic accidents annually worldwide and that of this number, about 3,000,000 people are severely injured and about 400,000 are killed. A report “The Economic Cost of Motor Vehicle Crashes 1994” by Lawrence J. Blincoe published by the United States National Highway Traffic Safety Administration estimates that motor vehicle crashes in the U.S. in 1994 caused about 5.2 million nonfatal injuries, 40,000 fatal injuries and generated a total economic cost of about $150 billion. Lack of driver attention and tailgating is estimated to be a cause of about 90% of driver related accidents. Methods and apparatus that would alert a driver to a potential crash and provide him or her with sufficient time to undertake accident avoidance action would substantially moderate automotive accident rates. For example a 1992 study by Daimler-Benz indicates that if passenger car drivers have a 0.5 second additional warning time of an impending rear end collision about 60 percent of such collisions can be prevented. An extra second of warning time would lead to a reduction of about 90 percent of rear-end collisions. Various systems collision warning/avoidance systems (CWAS) exist for recognizing an impending collision and warning a driver of the danger. U.S. Pat. No. 5,529,138, describes a CWAS that uses a laser radar to determine distance and relative velocity to determine a time to collision of a vehicle with an object. U.S. Pat. No. 5,646,612 describes a CWAS system comprising a laser radar and an infrared (IR) camera. A processor determines a time to collision (TTC) of a vehicle with an object responsive to signals provided by the laser radar and whether the object is a human, an animal or an inanimate object responsive to image data provided by the IR camera. The system operates to warn a driver of an impending collision with an object based on the TTC and kind of object “and properly performs deceleration and braking operations based on a position of the object and a speed of the vehicle is disclosed”. The disclosures of the above noted U.S. patents are incorporated herein by reference. Laser radar systems are relatively complicated systems that are generally expensive and tend to suffer from narrow field of view and relatively poor lateral resolution. PCT Publication WO 01/39018, the disclosure of which is incorporated herein by reference, describes a CWAS that comprises a camera and a processor for processing image data provided by the camera The camera provides images of an environment in which a vehicle is located and the processor determines a TTC of the vehicle with an obstacle by processing, optionally only, image data provided by the camera. The processor determines the TTC responsive to scale changes in the size of the obstacle as imaged in the images under the assumption that the relative velocity between the vehicle and the object is constant. SUMMARY OF THE INVENTION An aspect of some embodiments of the invention relates to providing an improved method and apparatus for determining at a given time t, a time to collision, TTC(t), of a vehicle with an object using a plurality of camera images of an environment in which the vehicle is located. An aspect of some embodiments of the invention relates to determining TTC(t) of the vehicle with the object by processing image data provided by the images without assuming that relative velocity between the vehicle and the object is substantially constant. In accordance with an embodiment of the invention, image data provided by the plurality of images is processed to provide an estimate of TTC(t), hereinafter Ta(t), which is responsive to the relative acceleration between the vehicle and the object. Optionally, only the image data is used to determine TTC(t). In accordance with an embodiment of the invention, to determine Ta(t), the image data is processed to determine for the given time t, a ratio, hereinafter referred to as relative scale “S(t)”, between dimensions of a feature of the object in different images of the plurality of the images. S(t) is used to determine an instantaneous relative velocity estimate for determining TTC(t), hereinafter Tv(t), at the given time. Tv(t) is equal to a distance between the vehicle and the object at time t divided by their instantaneous relative velocity. Tv(t) is estimated from S(t), optionally using methods and algorithms described in PCT Publication WO 01/39018 cited above. According to an aspect of some embodiments of the invention, relative acceleration is expressed as a function of a time derivative T′v(t) of Tv(t) at a given time and Ta(t) is determined as a function of the relative acceleration or a function of T′v(t). An aspect of some embodiments of the invention relates to determining whether a vehicle is on a collision course with an object responsive, to image data in a plurality of images of the vehicle environment that image the object. Optionally, only the image data is used to determine whether the objects are on a collision course. In accordance with an embodiment of the invention, the images are processed to determine trajectories for at least two features of the object toward which the vehicle is moving that substantially determine a width of the object parallel to the width of the vehicle. The vehicle and the object are determined to be on a collision course if, as the vehicle and object approach each other, for example as indicated by a value determined for TTC(t), the trajectories of the at least two features bracket at least a portion of the vehicle. In general, the object is another vehicle on the roadway on which the vehicle is moving and the at least two features, which may for example be edges, taillights or headlights of the other vehicle, are optionally features that determine a magnitude for the width of the other vehicle. There is therefore provided in accordance with an embodiment of the present invention, a method of estimating a time to collision (TTC) of a vehicle with an object comprising: acquiring a plurality of images of the object; and determining a TTC from the images that is responsive to a relative velocity and relative acceleration between the vehicle and the object. Optionally the method comprises determining the relative velocity or a function thereof from the images and using the relative velocity or function thereof to determine TTC. Optionally, determining the relative velocity or function thereof, comprises determining a change in scale of an image of at least a portion of the object between images of the pluralities of images and using the change in scale to determine the relative velocity or function thereof. Additionally or alternatively the method comprises determining the relative acceleration or a function thereof from the images and using the relative acceleration or function thereof to determine TTC. Optionally, determining the relative acceleration or function thereof comprises determining a time derivative of the relative velocity or the function of the relative velocity. In some embodiments of the invention, TTC is determined only from information derived from the images. In some embodiments of the invention, the method comprises determining whether the vehicle and the object are on a course that leads to a collision at the TTC. Optionally, determining whether the vehicle and object are on a collision course comprises: determining motion of at least two features of the object relative to the vehicle from the images; and determining from the relative motions whether at TTC the first and second features straddle at least a part of the vehicle. There is further provided in accordance with an embodiment of the invention, apparatus for determining a time to collision (TTC) of a vehicle with an object comprising: at least one camera mounted in the vehicle and adapted for acquiring images of objects in the environment of the vehicle; and a processor that receives image data from the camera and processes the data to determine a TTC in accordance with a method of the invention. Optionally, the at least one camera comprises a single camera. Additionally or alternatively the apparatus comprises alarm apparatus for alerting a driver of the vehicle to a possible collision with the object responsive to the TTC. In some embodiments of the invention, the apparatus comprises alarm apparatus for alerting persons outside of the vehicle to a possible collision of the vehicle with the object responsive to the TTC. In some embodiments of the invention, the at least one camera images an environment in front of the vehicle. In some embodiments of the invention, the at least one camera images an environment in back of the vehicle. In some embodiments of the invention, the at least one camera images an environment to a side of the vehicle. There is therefore provided in accordance with an embodiment of the invention, a method of determining whether a first object and a second object are on a collision course comprising: acquiring an image of the second object from a position of the first object at each of a plurality of known times; determining motion of at least two features of the first object relative to the second object from the images; determining an estimate of a possible time to collision (TTC) of the first and second objects; and determining from the relative motions whether at the TTC, the first and second features straddle at least a part of the vehicle and if so that the objects are on a collision course. Optionally, determining motion of the at least two features comprises determining lateral motion of the features relative to the first object. Optionally, determining whether the features straddle the first object at the TTC comprises extrapolating lateral locations of the features at TTC from their motion at times at which the images are acquired. Optionally, determining TTC comprises determining TTC from the images. In some embodiments of the invention TTC is determined only from the images. There is further provided in accordance with an embodiment of the invention, a method of determining relative acceleration between a first and second object comprising: acquiring a plurality of images of the second object from locations of the first object; determining a change in scale of an image of at least a portion of the second object between images of the pluralities of images; using the change in scale to determine acceleration of a function of the acceleration. Optionally, the acceleration or function thereof is determined only from data in the images. BRIEF DESCRIPTION OF FIGURES Non-limiting examples of embodiments of the present invention are described below with reference to figures attached hereto, which are listed following this paragraph. In the figures, identical structures, elements or parts that appear in more than one figure are generally labeled with a same numeral in all the figures in which they appear. Dimensions of components and features shown in the figures are chosen for convenience and clarity of presentation and are not necessarily shown to scale. FIG. 1 schematically shows a first “following” vehicle having a collision warning/avoidance system (CWAS), operating to provide a warning of collision with a second “lead” vehicle in front of the following vehicle, in accordance with an embodiment of the present invention; FIG. 2 shows a graph that provides a comparison between TTC(t) for the vehicles shown in FIG. 1 determined equal to Tv(t) in accordance with prior art and TTC(t) determined equal to Ta(t), in accordance with an embodiment of the present invention; FIG. 3 shows a graph that compares the results of alerting the driver of the following vehicle to a possible collision with the lead vehicle in accordance with prior art and alerting the driver to a possible collision in accordance with the present invention; and FIG. 4 schematically illustrates determining whether a vehicle is on a collision course with another vehicle, in accordance with an embodiment of the present invention. DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION FIG. 1 schematically shows a first, lead vehicle 21 traveling along a road 20 followed by a second, following vehicle 22 having a CWAS 30 in accordance with an embodiment of the present invention. CWAS 30 comprises a camera 32 that images, by way of example, the environment in front of following vehicle 22 and a processor 34 that processes image data provided by the camera to repeatedly update an estimate of a time to collision (TTC) of a possible rear end collision of following vehicle 22 with lead vehicle 21. CWAS 30 comprises at least one device (not shown), for alerting a driver of following vehicle 22 to a possible collision with an object in front of the vehicle responsive to estimates of TTC provided by processor 34. At any given time t lead and following vehicles 21 and 22 are separated by a distance Z(t), hereinafter also referred to as “range”, have a relative velocity V(t), which is changing with a relative acceleration a(t) (which may of course be zero). In accordance with an embodiment of the invention, at time t processor 34 determines an estimate of time to collision TTC(t) to be equal to Ta(t), which is an estimate responsive to relative acceleration a(t), between lead vehicle 21 and following vehicle 22 at the given time. In accordance with an embodiment of the invention, processor 34 processes image data from a plurality of images to provide an estimate of relative scale S(t). Processor 34 determines S(t) from a ratio of dimensions of a feature of lead vehicle 21 in at least two different images of the lead vehicle acquired by camera 32 at times close to the given time. For example, assume that at first and second times t1 and t2, which define a time interval Δt that optionally includes the given time t, camera 32 acquires first and second images respectively of lead vehicle 21. Let a distance between two features of lead vehicle 21, or a dimension of a feature of the lead vehicle, such as for example width of the lead vehicle, have a length (as measured for example in pixels or millimeters) in the first and second images represented by w(t1) and w(t2) respectively. Then, optionally, S(t)=w(t2)/w(t1) (1) If at times t1 and t2 the lead and following vehicles 21 and 22 are separated by distances, i.e. “ranges”, Z(t1) and Z(t2) respectively, then assuming perspective projection of a scene imaged by camera 32 on a photosensitive surface of the camera S(t)=Z(t1)/Z(t2) (2) If the vehicles have an average relative velocity (assumed negative if distance between the vehicles is decreasing and positive if distance is increasing) V(t) during the time interval Δt, then assuming that Δt is relatively small, Z(t1)≅[Z(t2)−V(t)Δt] and S(t) may be written S(t)≅[Z(t2)−V(t)Δt]/Z(t2), (3) from which it can be shown after relatively straightforward manipulation, Z(t2)/V(t)≅−Δt/(S(t)−1). (4) Assuming that relative acceleration between lead and following vehicles 21 and 22 is zero (or that time to collision TTC(t) is independent of relative acceleration) TTC(t) for vehicles 21 and 22 may be estimated as equal to Tv(t), where Tv(t)=−Z(t)/V(t)≅−Z(t2)/V(t)=Δt/(S(t)−1), (5) (it is recalled that V(t) is defined negative if the vehicles are getting closer to each other). The foregoing derivation of TTC(t)=Tv(t), which assumes relative acceleration equal to zero and results in TTC(t) being dependent only on the instantaneous velocity, is based on the analysis presented in WO 01/39018 cited above. Abandoning the assumption of zero acceleration, in accordance with an embodiment of the present invention, TTC(t) is estimated as equal to Ta(t), which has a value optionally determined responsive to an equation of the form, Z(t+Ta(t))=0=Z(t)+V(t)Ta(t)+0.5a(t)Ta(t)2. (6) Equation 6 assumes that from time t until collision, relative acceleration between lead and following vehicles 21 and 22 is constant and equal to a(t) and that following time t by a time lapse equal to Ta(t), range is equal to zero, i.e. the vehicles have contacted. Solving equation 6 for Ta(t) provides an expression: Ta(t)=(−V(t)+[V(t)2−2Z(t)a(t)]1/2)/a(t). (7) To evaluate Ta(t) the inventors have noted that a time derivative T′v(t) of Tv(t) may be written (note equation 5 above), T′v(t)=d(−Z(t)/V(t))/dt=−Z′(t)/V(t)+Z(t)a(t)/V(t)2=(a(t)Z(t)/V(t)2)−1 (8) It is convenient to define a parameter C(t), where C(t)=T′v(t)+1=a(t)Z(t)/V(t)2, (9) from which, a(t)=C(t)V(t)2/Z(t). (10) Substituting the expression for a(t) from equation 10 into the expression for Ta(t) from equation 7, manipulating the results and using the expression Tv(t) from equation 5 provides a “compact” expression for Ta(t), namely Ta(t)=[Tv(t)/C(t)][1−(1+2C(t)]1/2 (11) In the above expressions, Tv(t) is optionally approximated by −Z(t2)/V(t)=Δt/(S(t)−1) (equation 5 above). T′v(t) is optionally determined by determining a time derivative responsive to values of Tv(t) determined in accordance with equation 5 for a plurality of different times t. For example, optionally, a plurality of values of Tv(t) determined for a plurality of different times t, optionally before a given time t, are used to determine, using any of various methods known in the art, an analytic curve for Tv(t) as a function of time. The time derivative of the analytic curve evaluated for the given time t provides T′v(t) for the given time. To provide a numerical example that compares determining TTC(t)=Ta(t), in accordance with an embodiment of the present invention, with determining TTC(t) in accordance with prior art in which TTC(t)=Tv(t), assume that two vehicles are traveling at a same velocity equal to 70 kmph. Assume that the vehicles are separated by a range equal to 50 m and that at a time t=0 the “lead” driver of lead vehicle 21 spots an obstacle on road 20 and “hits” the brakes to decelerate at a maximum, constant, deceleration equal to 7.5 m/s2 to stop the lead vehicle. Assume that at the time that the lead driver hits his or her brakes, the driver of following vehicle 22 has shifted his or her attention from the road in front of him or her and is looking at a road sign at the side of the road. As a result, the “following” driver does not notice the brake lights of lead vehicle 21 turning on at t=0 when the lead driver hits the brakes or does not pay sufficient attention to the brake lights of the lead vehicle turning on. The driver of following vehicle 22 must rely on CWAS 30 to provide a warning of a possible rear end collision with lead vehicle 21 with sufficient lead-time to prevent the collision. Finally, assume that when alerted, the “following” driver applies the brakes to decelerate following vehicle 22, also at a constant deceleration of 7.5 m/s2 and that from a time at which the following driver is alerted to a danger there is a lag reaction time of about 1.6 seconds until the driver effectively applies the brakes of the following vehicle. (Driver reaction times are noted on page 27 of “Vehicle and Infrastructure-Based Technology for the Prevention of Rear-End Collisions”; Special Investigation Report, No. PB2001-917003, published by the National Transportation Safety Board, Washington D.C. May 1, 2001. On page 27 the report notes that “typical driver perception-reaction time ranges from 0.9 to 2.1 seconds with the 95-th percentile reaction time of 1.6 seconds”) FIG. 2 shows a graph 40 that provides a comparison between TTC(t) determined equal to Tv(t) and TTC(t) determined equal to Ta(t) in accordance with an embodiment of the present invention, subject to the assumptions described in the preceding paragraph. Curves 41 and 42 give values of Ta(t) and Tv(t) noted along the left hand ordinate of graph 40 as functions of time noted along the abscissa of the graph from the time t=0 at which lead driver of lead vehicle 21 applies the brakes. By way of example, it is assumed that CWAS 30 activates an alarm to alert a driver of following vehicle 22 to a possible collision if its evaluated TTC(t) is equal to or less than a collision alarm time (CAT) of about 2.8 seconds. CAT equal to 2.8 seconds is indicated in graph 40 by a line 44. From curve 41 and CAT line 44 it is seen that CWAS 30 alerts the driver of following vehicle 22 to a possible rear end collision with lead vehicle 21, in accordance with an embodiment of the invention, about 0.85 seconds after the driver of the lead vehicle has applied the brakes. Because of the 1.6 seconds lag in reaction time, the following driver manages to apply the brakes only at a time 2.45 seconds after the lead driver applies the brakes to lead vehicle 21. An arrow 46 indicates the elapsed time between the time at which the alert is given in accordance with an embodiment of the invention and a time at which the following driver applies the brakes. The discontinuity in Ta(t) occurs at a time at which the following driver applies the brakes and for a short period of time while lead vehicle 21 is still decelerating and the lead vehicle has not come to a full stop, the relative acceleration is zero. Similarly, from curve 42 it is seen that were CWAS 30 to alert the driver in accordance with prior art, i.e. TTC(t)=Tv(t), the following driver would be alerted to a possible collision at a time about 1.85 seconds after the driver of lead vehicle 21 applied the brakes. The alert provided by prior art is given almost a full second later than the alert provided by an embodiment of the invention and the following driver would only apply the brakes at a time of about 3.45 seconds after the lead driver applies the brakes. An arrow 48 indicates the elapsed time between the time at which the alert is given in accordance with prior art and a time at which the following driver applies the brakes. The import of the added warning time afforded the driver by an embodiment of the present invention is that the driver of following vehicle 22 avoids a collision with lead vehicle 21 that the driver would not avoid given an alert based on TTC(t)=Tv(t). FIG. 3 shows a graph 50 that compares the results of alerting the driver in accordance with an embodiment of the present invention, i.e. TTC(t)=Ta(t), for CAT=2.8 seconds with results of alerting the driver in accordance with prior art i.e. TTC(t)=Tv(t) for the same CAT. Curve 51, also labeled Za(t) in an upper portion 54 of graph 50 gives range between lead vehicle 21 and following vehicle 22 as a function of time after the driver in lead vehicle 21 applies the brakes for the case in which the driver of following vehicle 22 applies the brakes after being alerted by CWAS 30, in accordance with an embodiment of the invention. Curve 61, also labeled Va(t), in a bottom part 64 of graph 50, corresponds to curve 51 and gives the relative velocity between lead and following vehicle 21 and 22 for the case where the driver of following vehicle 22 applies the brakes responsive to an alert in accordance with the invention. Curve 52, also labeled Zv(t), in upper portion 54 of graph 50 gives range between lead vehicle 21 and following vehicle 22 were the driver in following vehicle 22 to apply the brakes responsive to an alert in accordance with the prior art. Curve 62 in bottom part 64 corresponds to curve 52 and gives the relative velocity Vv(t) between the lead and following vehicles were the driver of following vehicle 22 to apply the brakes responsive to an alert based on the prior art. Curve 51 shows that range Za(t) between lead and following vehicles never reaches zero, but instead both vehicles come to a full stop with a range between the vehicles equal to about 0.4 m at a time equal to about 5.2 seconds after the lead driver applies the brakes. Curve 61 shows that relative velocity Va(t), which is equal to zero before the driver of lead vehicle 21 applies the brakes (both lead and following vehicles 21 and 22 are traveling at a same velocity), decreases rapidly during a period in which lead vehicle 21 is decelerating after being braked until a time at which the driver of following vehicle 22 manages to apply the brakes. Thereafter, for a short time, until lead vehicle 21 comes to a full stop, relative velocity is constant while both vehicles lead and following vehicles 21 and 22 decelerate at a same acceleration (7.5 m/s2) and relative acceleration is zero. After lead vehicle 21 comes to a stop at a time indicated by an arrow witness line 69 also labeled with the word “STOP”, the relative velocity increases rapidly to zero as deceleration of following vehicle 22 provides a positive relative acceleration. Curves 52 and 62 indicate a substantially different scenario than curves 51 and 61. Curve 51 shows that range Zv(t) crosses zero and following vehicle 22 “meets” lead vehicle 21 at a time equal to about 4 seconds indicated by an arrow witness line 71, also labeled “CRASH”. Curve 62 shows that at the time that the vehicles meet, the magnitude of relative acceleration Vv(t) is quite large, indicating that following vehicle 22 does not contact lead vehicle 21 gently, but crashes into lead vehicle with substantial force. It is noted that whereas in the above described scenario, sufficient warning is provided by CWAS 30 to prevent a crash, a warning in accordance with an embodiment of the invention, if not sufficient to prevent a crash, will in general provide relatively more time to mitigate severity of a crash. Whereas a method in accordance with an embodiment the invention for determining TTC(t) in accordance with Ta(t) can provide an improved determination of TTC(t), it does not by itself determine whether, if no action is taken by a driver, a collision will actually occur. For example, a lead vehicle may be located in a driving lane adjacent to that in which a following vehicle is located. A CWAS in the following vehicle, using only a method similar to that described above, may determine that the following vehicle will rear-end the lead vehicle at a particular TTC, when in fact the following vehicle is not on a collision course with the lead vehicle but will just pass the lead vehicle at the particular TTC. In accordance with an embodiment of the invention, a CWAS installed in a vehicle processes images provided by its camera not only to determine a TTC for the vehicle with an object, but also to determine whether the object and the vehicle are on a collision course. In accordance with an embodiment of the invention, the CWAS's processor determines trajectories for at least two features of an object with which the vehicle is closing that substantially determine a width of the object parallel to the width of the vehicle. The CWAS determines that the vehicle and the object are on a collision course if, as the vehicle and object approach each other, for example as indicated by TTC(t)=Ta(t), the trajectories of the at least two features bracket at least a portion of the vehicle comprising the CWAS. Usually, the object is another vehicle on the roadway on which the vehicle comprising the CWAS is moving and the at least two features, which may for example be edges, taillights or headlights of the other vehicle, are optionally features that determine a magnitude of the width of the other vehicle. FIG. 4 is a schematic birds-eye view of lead and following vehicles 21 and 22 on road 20 shown in FIG. 1 and illustrates a situation in which a CWAS, e.g. CWAS 30, in accordance with an embodiment of the invention operates to determine if the two vehicles are on a collision course. It is assumed, by way of example, that road 20 is a two lane highway that curves to the left and that lead vehicle 21 is in a right hand lane 61 and following vehicle 22 is in a left hand passing lane 62. Lanes 61 and 62 are separated by lane markings 63. Following vehicle 22 is accelerating, or has accelerated, to a passing velocity in order to pass lead vehicle 22 and is schematically shown in dashed lines at three different locations on highway 20 relative to lead vehicle 21 as the following vehicle passes the lead vehicle. Optionally, CWAS 34 is operating to update TTC(t) for following and passing vehicles 21 and 22 in accordance with an embodiment of the invention and determines TTC(t)=Ta(t). In accordance with an embodiment of the invention, processor 34 processes images provided by camera 32 to identify and locate at least two features that determine a width of lead vehicle 21 in each of a plurality of the images. Any of many various pattern recognition algorithms known in the art may be used to identify the features. For example, an edge detection algorithm may be used to identify edges 64A and 66B of lead vehicle 22 or taillights 66A and 66B that are separated by a distance substantially equal to the width of the vehicle. By way of example, it is assumed that processor 34 identifies and locates taillights 66A and 66B of lead vehicle 22 in each of a plurality of images as following vehicle 22 passes lead vehicle 21. In FIG. 4 lead vehicle 21 is schematically shown in an image 70 acquired by camera 32 at each of the positions of following vehicle 22 shown in the figure. For each position of vehicle 21, image 70 acquired at the position is shown immediately to the left of the vehicle. Features in images 70 are optionally located relative to an image x-y coordinate system having a center 72 located at a point in the images corresponding to the optic axis of camera 32. As following vehicle 22 draws near to lead vehicle 21, “taillight images” 66A′ and 66B′ of taillights 66A and 66B respectively move progressively to the right of center 72 along the x-axis. In accordance with an embodiment of the invention, processor 34 processes images 70 to determine whether motion of taillight images 66A′ and 66B′ along the x-axis of images acquired by camera 32 indicate whether vehicles 21 and 22 are on a collision course. Let the x-coordinates taillight images 66A′ and 66B′ in each of the images acquired by camera 32 be represented by xa(t) and xb(t) and let corresponding real space x-coordinates of taillights 66A and 66B relative to the location of camera 32 in vehicle 21 be respectively XA(t) and XB(t). For convenience of presentation the real space x-coordinate, XC, of camera 32 is defined equal to zero (i.e. the camera is at the origin of coordinates). At some initial time, to, at which a first image 70 of lead vehicle 21 is acquired by camera 32, the x-coordinates of taillight images 66A′ and 66B′ are xa(to) and xb(to) and let the range at time to of the lead vehicle relative to following vehicle 22 be Z(to). Using perspective projection it can be shown that the range Z(t) of lead vehicle 21 at a time t later than to may be expressed, Z(t)=[xa(t)−xb(t)]Z(to)/[xa(to)−xb(to)]. (12) Using equation 12, the real space x-coordinates of taillights 66A and 66B may be written, XA(t)=(xa(t)Z(to)/f)([xa(to)−xb(to)]Z(to)/[xa(t)−xb(t)]) (13) XB(t)=(xb(t)Z(to)/f)([xa(to)−xb(to)]Z(to)/[xa(t)−xb(t)]), (14) where f is the focal length of camera 32. In accordance with an embodiment of the invention, processor 34 processes image data provided by camera 32 to determine values for xa(ti) and xb(ti) and therefrom XA(ti) and XB(ti) responsive to equations 13 and 14 at a plurality of times ti equal to and greater than to. At a given time t, the processor extrapolates the determined values for XA(ti) and XB(ti) to provide values for XA(TTC(t)) and XB(TTC(t)). Optionally, TTC(t)=Ta(t). In accordance with an embodiment of the invention, if XA(TTC(t)) and XB(TTC(t)) straddle the coordinate XC of camera 32 (i.e. have opposite signs assuming XC=0) then processor 32 determines that lead and following vehicles 21 and 22 are on a collision course. It is noted that since a sufficient condition for XA(TTC(t)) and XB(TTC(t)) to straddle XC is that they have opposite signs, processor 32 can use an arbitrary value for Z(to) when determining if they straddle XC. However, if both XA(TTC(t)) and XB(TTC(t)) lie to the left or the right of XC, processor 32 cannot determine for sure, responsive only to equations 13 and 14 if lead and following vehicles 21 and 22 are, or are not, on a collision course without a realistic value for Z(to). For a given set of values for xa(ti) and xb(ti), Z(to) determines magnitudes of displacement of XA(TTC(t)) and XB(TTC(t)) from XC. In particular, if both XA(TTC(t)) and XB(TTC(t)) are displaced to a same, one side of XC, Z(to) determines if they are displaced sufficiently so that vehicles do not collide. In some embodiments of the invention, processor 34 processes images 70 using methods described in “Vision Based ACC with a single Camera: Bounds on Range and Range Rate Accuracy”; G. P. Stein, O. Mano and A. Shashua; Proceedings of IEEE Intelligent Vehicles Symposium (IV2003), pages 120-125, Jun. 9-11, 2003, Columbus, Ohio. USA; the disclosure of which is incorporated herein by reference, to determine a value for Z(to). For relatively short ranges up to about 20 to 30 meters motion parallax may optionally be used to determine a value for Z(to). Whereas in the above description of exemplary embodiments of the invention a CWAS was installed in the front end of a vehicle to alert the vehicle's driver to a possible collision with an object in front of the vehicle, a CWAS in accordance with an embodiment of the invention may of course be installed elsewhere in a vehicle. For example, a CWAS may be installed in the rear of a vehicle to alert the driver to a possible rear end collision or in the sides of the vehicle to alert the driver to possible side collisions. A CWAS installed in such locations of a vehicle may provide a driver with sufficient time to enable him to take action that might mitigate severity of a rear end or side collision. A CWAS in accordance with an embodiment of the invention may operate any of various alarms, for example audio, visual or tactile alarms, to alert a driver to a possible collision. However, it is noted that a possible collision between a vehicle comprising a CWAS and another vehicle, will in general have potential to affect more than the driver and occupants of the vehicle outfitted with the CWAS. The possible collision does of course have substantial potential to affect the driver and occupants of the other vehicle and persons in the immediate environment of the vehicles. Furthermore, were the driver of the other vehicle and persons in the immediate environment made aware of the possible collision in which they may be participants, they might be able to take action that contributes to avoiding the collision or mitigating its effects. Therefore, in accordance with some embodiments of the invention, a CWAS is configured to alert persons other than the driver of the vehicle in which it is installed to a potential collision. When a possible collision is anticipated by the CWAS it optionally operates an alarm or alarms that alert drivers of other vehicles and pedestrians in the environment of the vehicle to the possible collision. For example, the CWAS may control the vehicle's horn to generate a particular type of audio alarm or the vehicles lights to flash warning signals. It is noted that whereas in the exemplary embodiments, a CWAS is described as processing images provided by its camera to determine whether to alert a driver to a potential collision, a CWAS in accordance with an embodiment of the invention may process data additional to image data to determine risk of a potential collision. For example, the CWAS may use data provided by a vehicle's speedometer, or sensors that generate signals responsive to operation of the vehicle's brakes or gas pedal to determine risk of a collision. In addition, a CWAS in accordance with some embodiments of the invention may perform functions other than to warn a driver and optionally other persons of an impending collision. For example, if the CWAS determines responsive to a TTC that risk of a collision is greater than a predetermined risk level and that driver is not undertaking any collision avoidance action, the CWAS may be equipped to apply the brakes. In the description and claims of the present application, each of the verbs, “comprise” “include” and “have”, and conjugates thereof, are used to indicate that the object or objects of the verb are not necessarily a complete listing of members, components, elements or parts of the subject or subjects of the verb. The present invention has been described using detailed descriptions of embodiments thereof that are provided by way of example and are not intended to limit the scope of the invention. The described embodiments comprise different features, not all of which are required in all embodiments of the invention. Some embodiments of the present invention utilize only some of the features or possible combinations of the features. Variations of embodiments of the present invention that are described and embodiments of the present invention comprising different combinations of features noted in the described embodiments will occur to persons of the art. The scope of the invention is limited only by the following claims.

<SOH> BACKGROUND OF THE INVENTION <EOH>Automotive accidents are a major cause of loss of life and dissipation of resources in substantially all societies in which automotive transportation is common. It is estimated that over 10,000,000 people are injured in traffic accidents annually worldwide and that of this number, about 3,000,000 people are severely injured and about 400,000 are killed. A report “The Economic Cost of Motor Vehicle Crashes 1994” by Lawrence J. Blincoe published by the United States National Highway Traffic Safety Administration estimates that motor vehicle crashes in the U.S. in 1994 caused about 5.2 million nonfatal injuries, 40,000 fatal injuries and generated a total economic cost of about $150 billion. Lack of driver attention and tailgating is estimated to be a cause of about 90% of driver related accidents. Methods and apparatus that would alert a driver to a potential crash and provide him or her with sufficient time to undertake accident avoidance action would substantially moderate automotive accident rates. For example a 1992 study by Daimler-Benz indicates that if passenger car drivers have a 0.5 second additional warning time of an impending rear end collision about 60 percent of such collisions can be prevented. An extra second of warning time would lead to a reduction of about 90 percent of rear-end collisions. Various systems collision warning/avoidance systems (CWAS) exist for recognizing an impending collision and warning a driver of the danger. U.S. Pat. No. 5,529,138, describes a CWAS that uses a laser radar to determine distance and relative velocity to determine a time to collision of a vehicle with an object. U.S. Pat. No. 5,646,612 describes a CWAS system comprising a laser radar and an infrared (IR) camera. A processor determines a time to collision (TTC) of a vehicle with an object responsive to signals provided by the laser radar and whether the object is a human, an animal or an inanimate object responsive to image data provided by the IR camera. The system operates to warn a driver of an impending collision with an object based on the TTC and kind of object “and properly performs deceleration and braking operations based on a position of the object and a speed of the vehicle is disclosed”. The disclosures of the above noted U.S. patents are incorporated herein by reference. Laser radar systems are relatively complicated systems that are generally expensive and tend to suffer from narrow field of view and relatively poor lateral resolution. PCT Publication WO 01/39018, the disclosure of which is incorporated herein by reference, describes a CWAS that comprises a camera and a processor for processing image data provided by the camera The camera provides images of an environment in which a vehicle is located and the processor determines a TTC of the vehicle with an obstacle by processing, optionally only, image data provided by the camera. The processor determines the TTC responsive to scale changes in the size of the obstacle as imaged in the images under the assumption that the relative velocity between the vehicle and the object is constant.

<SOH> SUMMARY OF THE INVENTION <EOH>An aspect of some embodiments of the invention relates to providing an improved method and apparatus for determining at a given time t, a time to collision, TTC(t), of a vehicle with an object using a plurality of camera images of an environment in which the vehicle is located. An aspect of some embodiments of the invention relates to determining TTC(t) of the vehicle with the object by processing image data provided by the images without assuming that relative velocity between the vehicle and the object is substantially constant. In accordance with an embodiment of the invention, image data provided by the plurality of images is processed to provide an estimate of TTC(t), hereinafter T a (t), which is responsive to the relative acceleration between the vehicle and the object. Optionally, only the image data is used to determine TTC(t). In accordance with an embodiment of the invention, to determine T a (t), the image data is processed to determine for the given time t, a ratio, hereinafter referred to as relative scale “S(t)”, between dimensions of a feature of the object in different images of the plurality of the images. S(t) is used to determine an instantaneous relative velocity estimate for determining TTC(t), hereinafter T v (t), at the given time. T v (t) is equal to a distance between the vehicle and the object at time t divided by their instantaneous relative velocity. T v (t) is estimated from S(t), optionally using methods and algorithms described in PCT Publication WO 01/39018 cited above. According to an aspect of some embodiments of the invention, relative acceleration is expressed as a function of a time derivative T′ v (t) of T v (t) at a given time and T a (t) is determined as a function of the relative acceleration or a function of T′ v (t). An aspect of some embodiments of the invention relates to determining whether a vehicle is on a collision course with an object responsive, to image data in a plurality of images of the vehicle environment that image the object. Optionally, only the image data is used to determine whether the objects are on a collision course. In accordance with an embodiment of the invention, the images are processed to determine trajectories for at least two features of the object toward which the vehicle is moving that substantially determine a width of the object parallel to the width of the vehicle. The vehicle and the object are determined to be on a collision course if, as the vehicle and object approach each other, for example as indicated by a value determined for TTC(t), the trajectories of the at least two features bracket at least a portion of the vehicle. In general, the object is another vehicle on the roadway on which the vehicle is moving and the at least two features, which may for example be edges, taillights or headlights of the other vehicle, are optionally features that determine a magnitude for the width of the other vehicle. There is therefore provided in accordance with an embodiment of the present invention, a method of estimating a time to collision (TTC) of a vehicle with an object comprising: acquiring a plurality of images of the object; and determining a TTC from the images that is responsive to a relative velocity and relative acceleration between the vehicle and the object. Optionally the method comprises determining the relative velocity or a function thereof from the images and using the relative velocity or function thereof to determine TTC. Optionally, determining the relative velocity or function thereof, comprises determining a change in scale of an image of at least a portion of the object between images of the pluralities of images and using the change in scale to determine the relative velocity or function thereof. Additionally or alternatively the method comprises determining the relative acceleration or a function thereof from the images and using the relative acceleration or function thereof to determine TTC. Optionally, determining the relative acceleration or function thereof comprises determining a time derivative of the relative velocity or the function of the relative velocity. In some embodiments of the invention, TTC is determined only from information derived from the images. In some embodiments of the invention, the method comprises determining whether the vehicle and the object are on a course that leads to a collision at the TTC. Optionally, determining whether the vehicle and object are on a collision course comprises: determining motion of at least two features of the object relative to the vehicle from the images; and determining from the relative motions whether at TTC the first and second features straddle at least a part of the vehicle. There is further provided in accordance with an embodiment of the invention, apparatus for determining a time to collision (TTC) of a vehicle with an object comprising: at least one camera mounted in the vehicle and adapted for acquiring images of objects in the environment of the vehicle; and a processor that receives image data from the camera and processes the data to determine a TTC in accordance with a method of the invention. Optionally, the at least one camera comprises a single camera. Additionally or alternatively the apparatus comprises alarm apparatus for alerting a driver of the vehicle to a possible collision with the object responsive to the TTC. In some embodiments of the invention, the apparatus comprises alarm apparatus for alerting persons outside of the vehicle to a possible collision of the vehicle with the object responsive to the TTC. In some embodiments of the invention, the at least one camera images an environment in front of the vehicle. In some embodiments of the invention, the at least one camera images an environment in back of the vehicle. In some embodiments of the invention, the at least one camera images an environment to a side of the vehicle. There is therefore provided in accordance with an embodiment of the invention, a method of determining whether a first object and a second object are on a collision course comprising: acquiring an image of the second object from a position of the first object at each of a plurality of known times; determining motion of at least two features of the first object relative to the second object from the images; determining an estimate of a possible time to collision (TTC) of the first and second objects; and determining from the relative motions whether at the TTC, the first and second features straddle at least a part of the vehicle and if so that the objects are on a collision course. Optionally, determining motion of the at least two features comprises determining lateral motion of the features relative to the first object. Optionally, determining whether the features straddle the first object at the TTC comprises extrapolating lateral locations of the features at TTC from their motion at times at which the images are acquired. Optionally, determining TTC comprises determining TTC from the images. In some embodiments of the invention TTC is determined only from the images. There is further provided in accordance with an embodiment of the invention, a method of determining relative acceleration between a first and second object comprising: acquiring a plurality of images of the second object from locations of the first object; determining a change in scale of an image of at least a portion of the second object between images of the pluralities of images; using the change in scale to determine acceleration of a function of the acceleration. Optionally, the acceleration or function thereof is determined only from data in the images.

20071129

20111220

20090604

60995.0

G08G116

PERUNGAVOOR, SATHYANARAYA V

COLLISION WARNING SYSTEM

UNDISCOUNTED

ACCEPTED

G08G

ACCEPTED

Image sensor test system

An image sensor test system (10) bringing input/output terminals of an image sensor into contact with a contact (61) of a test head (60), emitting light to alight receiving surface of the image sensor from a light source (80) and, while doing so, inputting/outputting electrical signals between the contact (61) of the test head (60) and the image sensor so as to test the optical properties of the image sensor, provided with a loader use inverting device (32) for inverting an image sensor loaded into a supply tray stacker in a state with the light receiving surface facing upward, a contact arm (43) for gripping a back surface of an opposite side to the light receiving surface of the image sensor and moving the image sensor to bring the image sensor into contact with a contact (61) of the test head (60) in the state with the light receiving surface facing downward, and an unloader use inverting device inverting and unloaded the tested image sensor.

1. An image sensor test system bringing input/output terminals of an image sensor into contact with a contact of a test head, emitting light to a light receiving surface of said image sensor from a light source and, while doing so, inputting/outputting electrical signals between the contact of said test head and said image sensor so as to test the optical properties of said image sensor, said image sensor test system provided with at least a pre-test sensor stacker for storing image sensors before testing, a loader use inverting means for inverting an image sensor supplied from said pre-test stacker, a contact arm for picking up and moving an inverted state image sensor inverted by said loader use inverting means and bringing input/output terminals of the inverted state image sensor into electrical contact with a contact of said test head, an unloader use inverting means for inverting an image sensor finished being tested, and a plurality of post-test sensor stackers for storing tested image sensors inverted by said unloader use inverting means. 2. An image sensor test system as set forth in claim 1, wherein each of said loader use inverting means and said unloader use inverting means can simultaneously invert two or more image sensors. 3. An image sensor test system as set forth in claim 1, wherein each of said loader use inverting means and said unloader use inverting means has at least a first holder able to hold an image sensor and a rotation mechanism for making said first holder rotate. 4. An image sensor test system as set forth in claim 3, wherein said first holder has a suction nozzle able to hold an image sensor by suction. 5. An image sensor test system as set forth in claim 4, wherein said first holder is exchangeable with another first holder having a suction nozzle different from the suction nozzle of that first holder so as to match with the size or shape of said image sensor. 6. An image sensor test system as set forth in claim 3, wherein said rotation mechanism has a pinion gear supporting said first holder and a rack gear intermeshing with said pinion gear and converts linear force supplied to said rack gear to rotational force so as to make said first holder rotate. 7. An image sensor test system as set forth in claim 3, wherein each of said loader use inverting means and said unloader use inverting means further has a second holder able to hold an image sensor after inversion and said second holder is formed with a recess able to hold said image sensor. 8. An image sensor test system as set forth in claim 7, wherein said second holder is exchangeable with another second holder formed with a recess different from the recess formed in that second holder so as to match with the size or shape of said image sensor. 9. An image sensor test system as set forth in claim 1, further provided with an imaging means able to obtain an image of a back surface of said image sensor after being inverted by said loader use inverting means and before being supplied to said test head. 10. An image sensor test system as set forth in claim 9, further provided with a judging means for judging an emission pattern of light emitting from said light source and an input pattern of electrical signals input from a contact of said test head based on image information obtained by said imaging means. 11. An image sensor test system as set forth in claim 9, further provided with selecting means for selecting a tested sensor stacker for unloading said image sensor to from among said plurality of tested sensor stackers based on device type information obtained by said imaging means and classification information of the test results. 12. A test method for an image sensor which brings input/output terminals of an image sensor into contact with a contact of a test head, emits light to a light receiving surface of said image sensor from a light source, and, while doing so, inputs and outputs electrical signals between the contact of said test head and said image sensor so as to test the optical properties of said image sensor, comprising at least a first inversion step of inverting an image sensor before testing, a test step of bringing the inverted state image sensor into electrical contact with a contact of said test head and emitting light on a light receiving surface of that image sensor from a light source to test the optical properties of that image sensor, and a second inversion step of inverting the tested inverted state image sensor. 13. A test method for an image sensor as set forth in claim 12, holding and simultaneously inverting two or more image sensors in said first inversion step and said second inversion step. 14. A test method for an image sensor as set forth in claim 12, further comprising, before said test step, an imaging step of obtaining an image of an image sensor to obtain device type information. 15. A test method for an image sensor as set forth in claim 14, further comprising a judgment step of judging an emission pattern of light emitted from said light source and an input pattern of electrical signals input from a contact of said test head based on the device type information obtained at said imaging step and, in said test step, emitting light to the light receiving surface of said image sensor in accordance with said emission pattern and inputting and outputting electrical signals between the contact of said test head and said image sensor in accordance with said input pattern. 16. A test method for an image sensor as set forth in claim 14, further comprising sorting tested image sensors based on the device type information obtained at said imaging step and classification information of the test results. 17. An electronic device test system bringing input/output terminals of an electronic device under test into electrical contact with a contact of a test head and inputting/outputting electrical signals between the contact of said test head and said electronic device so as to test said electronic device, said electronic device test system provided with at least a pre-test electronic device stacker for storing electronic devices before testing, a loader use inverting means for inverting an electronic device supplied from said pre-test electronic device stacker, a contact arm for picking up and moving an inverted state electronic device inverted by said loader use inverting means and bringing input/output terminals of the inverted state electronic device into electrical contact with a contact of said test head, an unloader use inverting means for inverting an electronic device finished being tested to its original state, and a plurality of post-test electronic device stackers for storing tested electronic devices inverted by said unloader use inverting means.

TECHNICAL FIELD The present invention relates to an image sensor test system and electronic device test system provided with a function of inverting electronic devices under test for testing. In particular, the present invention relates to an image sensor test system for inverting CCD sensors or CMOS sensors or other image sensors, bringing the input/output terminals of the image sensors into electrical contact with contacts of a test head, emitting light to light receiving surface of the image sensors from a light source, and, while doing so, inputting and outputting electrical signals with that image sensors so as to test the optical properties of the image sensors. TECHNICAL FIELD In an electronic device test system called a “handler”, large numbers of semiconductor integrated circuit devices and other electronic devices are placed on trays and loaded into the handler where the electronic devices under test are then individually brought into electrical contact with a test head and tested by the electronic device test system unit (hereinafter referred to as the “tester”). After the Lest ends, each electronic device is discharged from the test head and placed on a tray in accordance with the test results so as to sort the devices into categories such as good devices and defective devices and then unload them from the handler. In testing, among these electronic devices, CCD sensors, CMOS sensors, and other image sensors, in the same way as explained above, each image sensor is brought into electrical contact with the test head and sorted in accordance with the test results. Further, in this test, by bringing the image sensors into electrical contact with the test head and while doing this emitting light to the light receiving surfaces or the image sensors from a light source, optical property tests such as a pupil inspection for inspecting if the amount of light received by each image sensor is constant or not are performed. In a conventional image sensor test system for testing the optical properties of image sensors, due to the relation with the mounting step etc. after the test step, the image sensors are loaded and unloaded with their light-receiving surfaces facing upward, so they are moved in that state (that is, the state with the light receiving surfaces facing up) to the test head where the image sensors are then tested in the state with their light receiving surfaces facing upward. Further, in the conventional image sensor test system, the handler itself was provided with the light source. Since, as explained above, the sensors were tested in the state with their light receiving surfaces facing upward, the light source was arranged positioned above the image sensors. However, it testing image sensors in the state with their light receiving surfaces facing upward, the light receiving surfaces sometimes became covered with dust. This was liable to obstruct high accuracy tests. Further, in recent image sensor test systems, there has been a demand for improving the test efficiency by increasing the number of simultaneous measurements. If as explained above, however, the handler itself mounts the light source positioned above the image sensors, an increase in the number of simultaneous measurements would lead to an increase in the number of the light sources and a larger size of the light sources, so handler and light source design would be restricted and securing a large number of simultaneous measurements would be difficult. DISCLOSURE OF SHE INVENTION The present invention has as its object to provide an image sensor test system enabling high accuracy tests of image sensors and enabling a large number of simultaneous measurements to be easily handled. (1) To achieve the above-mentioned object, according to a first aspect of the present invention, there is provided an image sensor test system bringing input/output terminals of an image sensor into contact with a contact of a test head, emitting light to a light receiving surface of the image sensor from a light source and, while doing so, inputting/outputting electrical signals between she contact of the test head and the image sensor so as to test the optical properties of the image sensor, the image sensor test system provided with at least a pre-test sensor stacker for storing image sensors before testing, a loader use inverting means for inverting an image sensor supplied from the pre-test stacker, a contact arm for picking up and moving an inverted state image sensor inverted by the loader use inverting means and bringing input/output terminals of the inverted state image sensor into electrical contact with a contact of the test head, an unloader use inverting means for inverting an image sensor finished being tested, and a plurality of post-test sensor stackers for storing tested image sensors inverted by the unloader use inverting means (see claim 1). According to the first aspect of the present invention, an image sensor test system for testing optical properties of an image sensor is provided with a loader use inverting means for inverting an image sensor before testing and an unloader use inverting means for inverting a tested image sensor. Due to this, it becomes possible to invert an image sensor, loaded in a state with its light receiving surface facing upward, by an inverting means so that its light receiving surface faces downward, bring that inverted image sensor into contact with a contact of the test head by the contact arm so as to test it, then again invert that tested image sensor by the inverting means to make its light receiving surface face upward and unload it. Therefore, an image sensor can be tested in the state with its light receiving surface facing downward, so the light receiving surface can be prevented from being covered by dust and high accuracy tests can be performed. Further, since the image sensor can be tested in the state with its light receiving surface facing downward, it is possible to provide a light source under the image sensor separate from the handler, so the design freedom of the handler and light source is greatly improved and increases in the number of simultaneous measurements can be easily handled. While not particularly limited to in the above invention, each of the loader use inverting means and the unloader use inverting means preferably can simultaneously invert two or more image sensors (see claim 2). Due to this, the throughput of conveyance of the image sensor test system is improved. Specifically, each of the loader use inverting means and the unloader use inverting means nay be configured so as to have at least a first holder able to hold an image sensor and a rotation mechanism for making the first holder rotate (see claim 3). While not particularly limited to in the above invention, the first holder preferably has a suction nozzle able to hold an image sensor by suction (see claim 4). Due to this, safe and accurate inversion operations can be performed. Further, while not particularly limited to in the above invention, the first holder may be configured to be exchangeable with another first holder having a suction nozzle different from the suction nozzle of that first holder so as to match with the size or shape of the image sensor (see claim 5). Due to this, a single image sensor test system can handle a large number of types of image sensors. While not particularly limited to in the above invention, the rotation mechanism can be configured to have a pinion gear supporting the first holder and a rack gear intermeshing with the pinion gear and to convert linear force supplied to the rack gear to rotational force so as to make the first holder rotate (see claim 6). Due to this, a rotation mechanism enabling stable rotary operation can be configured cheaply and simply. While not particularly limited to in the above invention, each of the loader use inverting means and the unloader use inverting means may be configured to further have a second holder able to hold an image sensor after inversion and to have the second holder formed with a recess able to hold the image sensor (see claim 7). An inverted image sensor can be positioned relative to a contact of the test head by that recess. Further, while not particularly limited to in the above invention, the second holder may be configured to be exchangeable with another second holder formed with a recess different from the recess formed in that second holder so as to match with the size or shape of the image sensor (see claim 8). Due to this, a single image sensor test system can handle a large number of types of image sensors. While not particularly limited to in the above invention, the system may be further provided with an imaging means able to obtain an image of a back surface of the image sensor after being inverted by the loader use inverting means and before being supplied to the test head (see claim 9), may be further provided with a judging means for judging an emission pattern of light emitted from the light source and an input pattern of electrical signals input from contacts of the test head based on image information obtained by the imaging means (see claim 10), and may be further provided with selecting means for selecting a tested sensor stacker for unloading the image sensor to from among the plurality of tested sensor stackers based on device type information obtained by the imaging means and classification information of the test results (see claim 11). (2) Further, to achieve the above-mentioned object, according so a second aspect of the present invention, there is provided a test method for an image sensor which brings input/output terminals of an image sensor into contact with a contact of a test head, emits light to a light receiving surface of she image sensor from a light source, and, while doing so, inputs and outputs electrical signals between the contact of the test head and the image sensor so as to test the optical properties of the image sensor, comprising at least a first inversion step of inverting an image sensor before testing, a test step of bringing the inverted state image sensor into electrical contact with a contact of the test head and emitting light to a light receiving surface of that image sensor from a light source to test the optical properties of that image sensor, and a second inversion step of inverting the tested inverted state image sensor (see claim 12). According to the second aspect of the present invention, there is provided a test method of an image sensor which inverts an image sensor before testing by a first inversion step and inverts the tested image sensor by a second inversion step. Due to this, it becomes possible to invert an image sensor loaded in a state with its light receiving surface facing upward before testing so that its light receiving surface faces downward and bring that inverted state image sensor into contact with a contact of a test head for testing, then again invert the tested image sensor to unload it with its light receiving surface facing upward. Therefore, an image sensor can be tested in the state with its light receiving surface facing downward, so the light receiving surface can be prevented from being covered by dust and high accuracy tests can be performed. Further, since an image sensor can be tested in the state with its light receiving surface facing downward, it is possible to provide a light source under the image sensor separate from the handler, so the design freedom of the handler and light source is greatly improved and increases in the number of simultaneous measurements can be easily handled. While not particularly limited to in the above invention, it is preferable to hold and simultaneously invert two or more image sensors in the first inversion step and the second inversion step (see claim 13). Due to this, the throughput of conveyance or the image sensor test system is improved. While not particularly limited to in the above invent on, the method may be configured to further comprise, before the test step, an imaging step of obtaining an image of an image sensor to obtain device type information (see claim 14), may be configured to further comprise a judgment step of judging an emission pattern of light emitted from the light source and an input pattern of electrical signals input from a contact of the test head based on the device type information obtained at the imaging step and, in the test step, to emit light to the light receiving surface of the image sensor in accordance with the emission pattern and input and output electrical signals between a contact of the test head and the image sensor in accordance with the input pattern (see claim 15), and may be configured to sort tested image sensors based on the device type information obtained at the imaging step and classification information of the test results (see claim 16). (3) Further, to achieve the above-mentioned object, according to a third aspect of the present invention, there is provided an electronic device test system bringing input/output terminals of an electronic device under test into electrical contact with a contact of a test head and inputting/outputting electrical signals between the contact of the test head and the electronic device so as to test the electronic device, the electronic device test system provided with at least a pre-test electronic device stacker for storing electronic devices before testing, a loader use inverting means for inverting an electronic device supplied from the pre-test electronic device stacker, a contact arm for picking up and moving an inverted state electronic device inverted by the loader use inverting means and bringing input/output terminals of the inverted state electronic device into electrical contact with a contact of the test head, an unloader use inverting means for inverting an electronic device finished being tested to its original state, and a plurality of post-test electronic device stackers for storing tested electronic devices inverted by the unloader use inverting means (sac claim 17). BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a plan view of an image sensor to be tested by an image sensor test system of a first embodiment of the present invention. FIG. 1B is a sectional view of the image sensor along the line I-I of FIG. TA. FIG. 2 is a schematic plan view of an image sensor test system according to an embodiment of the present invention. FIG. 3 is a sectional view of the image sensor test system along the line II-II of FIG. 2. FIG. 4 is a perspective view of a loader use inverting device of an image sensor test system according to an embodiment of the present invention. FIG. 5A is a plan view of the loader use inverting device shown in FIG. 4. FIG. 5B is aside view of the loader use inverting device shown in FIG. 4. FIG. 6A is a side schematic view for explaining the operation of the loader use inverting device shown in FIG. 4 and shows the state before inversion. FIG. 6B is a side schematic view for explaining the operation of the loader use inverting device shown in FIG. 4 and shows the state after inversion. FIG. 7 is a view of the state of identification of the type or image sensor in an image sensor test system according to an embodiment of the present invention. FIG. 8 is a block diagram showing the system configuration for identifying the test of an image sensor in an image sensor test system according to an embodiment of the present invention. FIG. 9 is a schematic sectional view of a tester of an image sensor test system according to an embodiment of the present invention. FIG. 10A is a sectional view of an image sensor of a type with input/output terminals led out from the sides with respect to the light receiving surface. FIG. 10B is a sectional view of an image sensor of a type with input/output terminals led out from the opposite side from the light receiving surface. BEST MODE FOR WORKING THE INVENTION Below, embodiments of the present invention will be explained based on the drawings. FIG. 1A is a plan view of an image sensor to be tested by an image sensor test system according to a first embodiment of the present invention, while FIG. 1B is a sectional view or an image sensor along the line I-I of FIG. 1A. First, explaining an image sensor to be tested by an image sensor test system according to an embodiment of the present invention, this image sensor DUT, as shown in FIG. 1A, has a chip CH with microlenses arranged at its approximate center and has input/output terminals HB led out at the periphery. These chip CH and terminals HB are packaged to form a CCD sensor, CADS sensor, etc. As shown in FIG. 1B, it is a type of image sensor with input/output terminals HB led out from the same plane as the light receiving surface RL of the chip CH where the microlenses are formed. FIG. 2 is a schematic plan view of an Image sensor test system according to an embodiment of the present invention, while FIG. 3 is a sectional view of the image sensor test system along the line II-II of FIG. 2. The image sensor test system 10 of this embodiment of the present invention is a system for testing a type of image sensor DUT shown in the above-mentioned FIG. 1A and FIG. 1B. As shown in FIG. 2 and FIG. 3, it is provided with a sensor stacker 20, a loader 30, a tester 40, and an unloader 50 and can use the test head 60 and tester 70 (see FIG. 3) and light source 80 (see FIG. 3) to simultaneously test four image sensors DUT. This image sensor test system 10 supplies sensors from the sensor stacker 20 through the loader 30 to the tester 40, pushes them against the contacts 61 of the test head 60 at the tester 40, emits light from the light source 80 to the light receiving surfaces RL of the image sensors DUT and, while doing so, inputs and outputs electrical signals between the tester 70 and the image sensors DUT through the contacts 61 and input/output terminals HB for testing, then classifies the tested image sensors DUT through the unloader 50 in accordance with the classification information based on the test results and stores them in the sensor stacker 20. Below, the different parts of this image sensor test system 10 will be explained. Sensor Stacker 20 The sensor stacker 20, as shown in FIG. 2 and FIG. 3a is comprised of a supply tray stacker 21 (pre-test image sensor stacker), classification tray stackers 22 (rested image sensor stacker), an empty tray stacker 23, and a tray conveyor 24 and can store pre-test and tested image sensors DUT. The supply tray stacker 21 holds stacked together a plurality of supply trays on which a plurality of, for example about 20, image sensors DUT before testing are carried. In the present embodiment, the image sensors DUT before testing are unloaded through this supply tray stacker 21 to the inside of the image sensor test system 10 in the state with their light receiving surfaces RL facing upward. The classification tray stackers 22 hold stacked together a plurality of classification trays on which the plurality of tested image sensors DUT can be carried. In the example shown in FIG. 2, three classification tray stackers 22 are provided. Note that in general five or more classification tray stackers 22 are provided. By providing three classification tray stackers 22, for example, the image sensors DUT can be sorted and stored in a maximum of three classes in accordance with the test results such as good/defective devices and, among defective devices, ones for which retesting is required/not required. In the present embodiment, the tested image sensors DUT are unloaded through these classification tray stackers 22 to outside the image sensor test system 10 in the state with their light receiving surfaces RL facing upward. The empty tray stacker 23 stores the empty trays from which all pre-test image sensors DUT carried on the supply trays have beer supplied to she tester 30. The tray conveyor 24 is a means able to move trays in the XZ-axial direction in FIG. 2. It holds a tray emptied of image sensors DUT at the supply tray stacker 21 by suction pads 243, causes an Z-axial direction actuator (not shown) to rise, makes a movable head 242 slide along the X-axial direction rail 241 fixed on the table 12 of the image sensor test system 10, and conveys the empty tray to the empty tray stacker 23. On the other hand, when the classification trays are filled with tested image sensors DUT in a classification tray stacker 22, the tray conveyor 24 conveys empty trays from the empty tray stacker 23 and refills the classification tray stacker 22. Note that the numbers of stackers in the present invention are not particularly limited to the numbers explained above and may be suitably set in accordance with need. Loader 30 The loader 30, as shown in FIG. 2 and FIG. 3, is comprised of a loader use XYZ movement device 31, a loader use inverting device 32 (loader use inverting means), and a loader use YZ movement device 33 and is designed to be able to supply image sensors DUT from the supply tray stacker 21 of the sensor stacker 20 to the tester 40. The loader use XYZ movement device 31 is comprised of a Y-axial direction rail 311 fixed to a table 12 of the image sensor test system 10, an X-axial direction rail 312 supported to be able to slide in the Y-axial direction along this Y-axial direction rail 311, a movable head 313 supported to be able to slide in the X-axial direction along this X-axial direction rail 312, and four suction pads 314 supported through an Z-axial direction actuator (not shown) at its bottom end. This loader side XYZ movement device 31 can move the image sensors DUT carried on a supply tray of the supply tray stacker 21 of the sensor stacker 20 to the loader use inverting device 32. It is designed to be able to simultaneously move four image sensors DUT. FIG. 4 is a perspective view of a loader use inverting device of an image sensor test system according to an embodiment of the present invention, FIG. 5A is a plan view of the loader use inverting device shown in FIG. 4, FIG. 5B is a side view of the loader use inverting device shown in FIG. 4, and FIGS. 6A and B are side schematic views for explaining the operation of the loader use inverting device shown in FIG. 4, where FIG. 6A shows the state before inversion and FIG. 6B shows the state after inversion. The loader use inverting device 32, as shown in FIG. 4 to FIG. 6B, is comprised of a first holder 321 for holding image sensors DUT transported by the loader use XYZ movement device 31, a rotation mechanism 322 for making this first holder 321 rotate, a second holder 323 for holding image sensors DUT held by the first holder 321 rotated by this rotation mechanism 322, and an air cylinder 324 for supplying the drive force for inverting the image sensors DUT. The first holder 321 is comprised of a flat plate member 321a on which four suction nozzles 321b are attached and can hold image sensors DUT loaded in the state with their light receiving surfaces RL facing upward by suction at their back surfaces. These four suction nozzles 321b are arranged to correspond to the arrangement of the four contacts 61 of the test head 60. Further, the suction nozzles 321b of the first holder 321 are attached detachably at the plate member 321a by screws or other means. When for example a change of the lot of the image sensors etc. results in a change of the tested sensors to image sensors different in outer shape or form, the suction nozzles 321b can be exchanged with other suction nozzles having shapes or forms different from them so as to match with the changed image sensors. The rotation mechanism 322 is comprised of a pinion gear 322a supporting the first holder 321 and able to rotate about a shaft 322e, a rack gear 322b intermeshing with this pinion gear 322a and fixed to a piston rod 324a (see FIGS. 6A and B) of the air cylinder 324, a guide body 322c (see FIGS. 6A and B) to which this rack gear 322b is fixed by bolts etc., and a guide rail 322d on which this guide body 322c can slide in the Y-axial direction (see FIGS. 6A and B) and is designed to convert linear force supplied from the air cylinder 324 through the piston rod 324a to rotational force through the rack and pinion 322a and 322b and make the first holder 321 rotate. The second holder 323 is comprised of a flat plate member 323a on which four recesses 323b are formed. The recesses 323b have sizes enabling image sensors DUT to be held. Further, the recesses 323b are formed to correspond to the arrangement of the four contacts 61 of the test head 60 in the same way as the above-mentioned four suction nozzles 321b. By having the recesses 323b hold image sensors DUT, they are positioned relative to the contacts 61 of the test head 60. Note that the edges of the recesses 323b may be tapered so as to facilitate holding of the image sensors DUT in the recesses 323b. Further, the second holder 323 is attached detachably to the body of the loader side inverting device 32 by bolts or other means. When for example a change in the lot of the image sensors etc. results in a change of the tested sensors to image sensors different in shape, the second holder 323 can be exchanged with another second holder formed with recesses of different sizes from the recesses 323b so as to match with the changed image sensors. In the loader use inverting device 32 configured as explained above, as shown in FIG. 6A, the image sensors DUT moved by the loader use XYZ movement device 31 are held by suction by the suction nozzles 321a of the first holder 321 and, as shown in FIG. 6B, the air cylinder 324 is driven to make the rotation mechanism 322 rotate the first holder 321. When that first holder 321 rotates 1800, the suction is released and the image sensors DUT are dropped into the recesses 323b of the second holder 323. Due to this, the image sensors DUTZ loaded in the state with their light receiving surfaces RL facing upward can be supplied to the tester 40 inverted so that their light receiving surfaces RL face downward. Note that in the present embodiment, use of a rack and pinion mechanism to invert the image sensors DUT was explained, but the present invention is not particularly limited in means so long as the image sensors DUT can be rotated. For example, a link device etc. may be used to convert linear force from a cylinder etc. to rotational force, a gear mechanism, belt mechanism, chain mechanism, etc. may be used to convey rotational force supplied from a motor etc., or a rotary actuator etc. may be used to directly supply rotational force so as to invert the image sensors DUT. As the drive source for the linear force or rotational force supplied to these, air, electricity, oil pressure, etc. may be mentioned. Further, in the present embodiment, suction was illustrated as one means for the first holder 321 holding the image sensors DUT, but the present invention is not particularly limited to this. For example, it is also possible to use a mechanical chuck for gripping the top and bottom end faces of the image sensors. Further, in this case, it is also possible not to provide the loader side inverting device 32 with a second holder 323, but have the loader use YZ movement device 33 directly receive the image sensors DUT from the first holder 323 holding the inverted image sensors DUT. Further, the present embodiment was configured to rotate the first holder 321 holding the image sensors DUT by suction by the suction nozzles 321b, but the present invention is not particularly limited to this. For example, instead of providing suction nozzles, both of the first holder 321 and second holder 323 may be configured to rotate and the first holder 321 and the second holder 323 may be rotated while holding the image sensors DUT so as to invert the image sensors DUT. The loader use YZ movement device 33 is comprised of a Y-axial direction rail 331 fixed to the table 12 of the image sensor test system 10, a movable head 332 supported to be able to slide in the Y-axial direction along the Y-axial direction rail 331, and four suction pads 333 supported through a 2-axial direction actuator (not shown) at its bottom end. This loader use YZ movement device 33 is designed to be able to move the image sensors DUT held at the second holder 323 of the loader use inverting device 32 to any of the buffers 41 and is designed to be able to simultaneously move four image sensors DUT. Further, as shown in FIG. 2 and FIG. 3r the loader use inverting device 32 and the first buffer 31 of the tester 40 are provided between them with a spraying nozzle 34 able to spray nitrogen gas upward in the vertical direction. When moving the image sensors DUT inverted by the loader use inverting device 32 by the loader use YZ movement device 33 to the tester 40, the image sensors DUT passing above this spraying nozzle 34 may be sprayed with nitrogen gas sprayed by the sprayed nozzle 34 so as to clean the light receiving surfaces RL of the image sensors DUT. Note that the gas sprayed from spraying nozzle 34 is not limited to nitrogen gas. For example, it may also be compressed air supplied through a clean filter etc. FIG. 7 is a view of the state of identification of the type of image sensor in an image sensor test system according to an embodiment of the present invention, while FIG. 8 is a block diagram showing the system configuration for identifying the device type of an image sensor in an image sensor test system according to an embodiment of the present invention. The loader use YZ movement device 33, as shown in FIG. 7, is provided with a CCD camera or other camera 334 (imaging means) attached in a state with its optical axis facing vertically downward. This camera 334 can obtain an image of an image sensor DUT held in a recess 323a of the second holder 323 of the loader use inverting device 32. In particular, it is possible to obtain an image of the back surface of the image sensor DUT opposite to the light receiving surface RL. This camera 334, as shown in FIG. 8, is connected so that it can transmit the obtained image information to an image processing system 90. The image processing system 90, for example, has an image processing processor etc. By processing the image information obtained by the camera 334, it can read for example bar codes and other product information marked on the back surface of the image sensor DUT by ink marking, laser marking, or another means or past processing information and other device type information given in previous processes. This image processing system 90, as shown in FIG. 8, is connected so as to be able to transmit the results of Identification of the image sensor DUT, that is, the device type information, to the tester 70 and light source 80. Due to this, it becomes possible to run tests under test conditions suitable so the device type information. The tester 70 inputs electrical signals from the contacts 61 of the test head 60 to the input/output terminals HB of the image sensors DUT and uses the results of identification of the image processing system 90 to judge the input pastern of the electrical signals corresponding to the device type of the image sensors DUT. Further, the light source 80 emits light to the light receiving surfaces RL of the image sensors DUT at the time of tests and uses the results of identification of the image processing system 90 to judge the emission pattern corresponding to the device type of the image sensors DUT. The tester 70, light source 80, and image processing means 90 in the present embodiment correspond to an example of the judging means in the present invention. Further, the image processing system 90 is connected to be able to transmit the above-mentioned results of identification to a controller (not shown) of the image sensor test system 10. When sorting and storing the tested image sensors DUT in the plurality of classification tray stackers 22 as explained above, it can use the classification information and device type information of the test results to sort the image sensors DUT. Specifically, for example, when testing two types of image sensors DUT, that is, the Device Type A and Device Type B, it can sort and store good sensors of the Device Type A, defective sensors of the Device Type A, good sensors of the Device Type B, and defective sensors of the Device Type B in the classification tray stackers 22. Due to this, it becomes possible to suitably handle tests of short runs of diverse image sensors PUT. The controller (not shown) and image processing system 90 of the image sensor test system 100 correspond to an example of the selecting means of the present invention. Note that while not particularly shown, this loader 30 may, for example, be provided with a heat plate between the supply tray stacker 21 and the loader use inverting device 32 and apply the desired thermal stress so the image sensors before testing in accordance with need. Tester 40 FIG. 9 is a schematic cross-sectional view of a Lester of an image sensor test system according to an embodiment of the present invention. The tester 40 is comprised of two buffers 41 and 42 and a contact arm 413 and is designed to be able to use the Lest head 60 and light source 80 to test the optical properties of the image sensors DUT. It can bring the input/output terminals HR of the image sensors DUT into contact with the contacts 61 of the test head 60, emit light to the eight receiving surfaces of the image sensors DUT from the light source 80, and, while doing so, input and output signals between the contacts 61 and image sensors DUT so as to test whether or not the amounts of light received by the image sensors DUT are constant and other optical properties of the image sensors DUT. The contacts 61 are provided with openings 63 at their centers to enable light to be emitted to the light receiving surfaces RL of the image sensors DUT. First, explaining the test head 60 used in the tester 40, as shown in FIG. 9, this test head 60 is configured by a board on which four contacts 61 are arranged in two rows and two columns. These are arranged so as to substantially match with the arrangement of the holders of the later explained contact arm 43. Note that in FIG. 9, of the four contacts 61, the rear, side two contacts 61 are concealed by the front side two contacts 61, so only two contacts 61 are shown. The contacts 61 are provided with pluralities of contact pins 62. These contact pins 62 are arranged to substantially match the arrangement of the input/output terminals HB of the image sensors BUT of the device type to be tested. This test head 60, as shown in FIG. 3, is detachably attached to the image sensor test system 10 so as to fill the opening 11 formed in the table 12 of the image sensor test system 10. The contacts 61, as shown in the figure, are electrically connected through a cable 71 to the tester 70. Further, in the image sensor test system 10 according to the present embodiment, as shown in FIG. 9, it is made possible to emit light from below to the light receiving surfaces RL of the image sensors PUT by forming openings 63 at the substantial centers of the contacts 61 of the test head 60. The openings 63 have sizes of extents enabling visual recognition of the light receiving surfaces RL of the image sensors DUT from below. When a change in the device type of the image sensors DUT results in a change in the shapes of the image sensors DUT or the arrangement of input/output terminals HB, this test head 60 can be exchanged with another test head suitable for the changed image sensors DUT so as to enable a single image sensor test system 10 to handle tests for different types of image sensors DUT. The tester 40 of the image sensor test system 10 according to the present embodiment, as shown in FIG. 3 and FIG. 9, is provided with a light source 80 having four emission parts 81 able to emit light vertically downward and is designed to enable the emission parts 81 to simultaneously emit light through the openings 63 formed in the contacts 61 to the light receiving surfaces RL of the four image sensors DUT to be simultaneously tested. The first buffer 41 of the tester 40 is comprised of an X-axial direction rail 411 fixed to the table 12 of the image sensor test system 10, a pre-test buffer 412 able to slide in the X-axial direction along the X-axial direction rail 411, and a post-test buffer 413 able to glide integrally with this pre-test buffer 412 in the X-axial direction along the X-axial direction rail 411. This first buffer 41 is designed to be able to receive image sensors DUT transported by the loader use YZ movement device 33 to the tester 40 at the pro-test buffer 412, slide them along the X-axial direction rail 411, and supply them to the contact arm 43. Further, it is designed to be able, after the test, to receive the image sensors DUT discharged by the contact arm 43 at the post-test buffer 413, slide them along the X-axial direction rail 411, and move them to the operating region of the later explained unloader use YZ movement device 51. The surfaces of both of the pre-test buffer 412 and post-test buffer 413 are formed with recesses 412a, 413a having sizes able to hold the image sensors DUT. Mote that the edges of these recesses 412a, 413a may be tapered to facilitate holding of the image sensors DUT in the recesses 412a, 413a. The second buffer 42 is also comprised, like the first buffer 41, of an X-axial direction rail 421, a pre-test buffer 422, and a post-test buffer 423 and is designed to receive pre-test image sensors DUT from the loader use YZ movement device 33 at the pre-test buffer 422 and supply them to the contact arm 43 and to receive tested image sensors DUT from the contact arm 43 and move them to the operating region of the unloader use YZ movement device 51. In the image sensor test system 10 according to the present embodiment, by providing the two buffers 41, 42, while either of the first or second buffer 41, 42 is supplying the contact arm 43 with image sensors DUT for testing, the other second or first buffer 42, 41 car receive pre-test image sensors DUT from the loader use YZ movement device 33 or discharge tested image sensors DUT to the unloader use YZ movement device 51, so the test efficiency of the image sensor test system 10 can be raised. Note that the number of the buffers 42, 42 is non limited to two and may be suitably set in accordance with the testing time of the image sensors DUT etc. The contact arm 43, as shown in FIG. 2 and FIG. 3, is comprised of a Y-axial direction rail 431 fixed to the table 12 of the image sensor test system 10, a movable head 432 able to slide in the Y-axial direction along this Y-axial direction rail 431 and having a 2-axial direction actuator (not shown) able to slide in the Z-axial direction, and four suction pads 433 able to hold the image sensors DUT by suction. The four suction pads 433 are attached to the bottom surface of the movable head 432 so as to substantially match with the arrangement of the four contacts 61 provided at the test head 60. This contact arm 43 is designed to be able to simultaneously hold four image sensors DUT. It is designed to be able to simultaneously press the tour image sensors DUT supplied from the buffers 41, 42 against the contacts 61 of the test head 60, then simultaneously discharge the tested four image sensors DUT to the buffers 41, 42. Note that while not particularly shown, the movable head 432 may be provided with a built-in heater and temperature sensor to maintain the thermal stress applied by the above-mentioned heat plaza. Unloader 50 The unloader 50, as shown in FIG. 2 and FIG. 3, is comprised of an unloader use YZ movement device 51, an unloader use inverting device 52 (unloader use inverting means), and an unloader use XYZ movement device 53 and is designed to be able to unload tested image sensors DUT discharged from the tester 40 from the buffers 41, 42 to the sensor stacker 20. The unloader use YZ movement device 51, in the same way as the loader use YZ movement device 33, is comprised of a Y-axial direction rail 511 fixed to the table 12 of the image sensor test system 10, a movable head 512 supported movably in the Y-axial direction along the Y-axial direction rail 511, and four suction pads 513 supported through a Z-axial direction actuator (not shown) at its bottom end. This unloader use YZ movement device 51 is designed to be able to move image sensors DUT discharged from the Lester 40 from the first and second buffers 41, 42 to the unloader use inverting device 52. It is designed to be able to simultaneously move four image sensors DUT. The unloader use inverting device 52, in the same way as the above-mentioned loader use inverting device 32, is comprised of a first holder 521 comprised of a plate member provided with four suction nozzles, a rotation mechanism 522 for converting linear force supplied from an air cylinder to rotational force by a rack and pinion mechanism and making the first holder 521 rotate, and a second holder 523 comprised of a plate member formed with four recesses. This unloader use inverting device 52 holds the image sensors DUT transported by the unloader use YZ movement device 51 at the first holder 521 by suction, makes the first holder 521 rotate 180° by the rotation mechanism 522, then releases the suction and drops the image sensors DUT into the recesses of the second holder 523. Due to this, it becomes possible to unload image sensors DUT tested in the state with their light receiving surfaces RL facing downward to the sensor stacker 20 inverted so that their light receiving surfaces RL face upward. The unloader use XYZ movement device 53 is comprised of a Y-axial direction rail 531 fixed to the table 12 of the image sensor test system 10, an X-axial direction rail 532 supported to be able to slide in the Y-axial direction along the Y-axial direction rail 531, a movable head 533 supported to be able to slide in the X-axial direction along the X-axial direction rail 532, and four suction pads 534 supported through a Z-axial direction actuator (not shown) at its bottom end. This unloader use XYZ movement device 53 is designed to move and sort the image sensors BUT inverted by the unloader use inverting device 52 on to the classification trays of the classification tray stackers 22 of the sensor stacker 20 in accordance with the test results. Below, a test of the image sensors DUT by the image sensor test system 10 according to the present embodiment will be explained. First, the loader use XYZ movement device 31 uses the four suction pads 314 to pick up four image sensors D-JT carried on a supply tray of the supply tray stacker 21 of the sensor stacker 20. Note that the image sensors DUT are carried on the supply tray in the state with their light receiving surfaces RL facing upward. Next, the loader use XYZ movement device 31 moves the four image sensors DUT to position them at the suction nozzles 321b of the first holder 321 of the loader use inverting device 32, then releases the suction of the suction pads 314. Simultaneously with this, the suction nozzles 321b of the loader use inverting device 32 start suction and, as shown in FIG. 6A, hold the four image sensors DUT by the first holder 31 of the loader use inverting device 32. Next, the movement device drives the air cylinder 324 of the loader use inverting device 32 in a direction causing the piston rod 324a to extend, whereby, as shown in FIG. 6B, the rack gear 322b and guide body 322c slide along the guide rail 322d in the Y-axial negative direction, the pinion gear 322a intermeshed with that rack gear 322b rotates, and the first holder 321 holding the image sensors DUT rotates 180° (first inversion step). When the rotation of the pinion gear 322a leads to the first holder 321 rotating 180°, the four image sensors DUT held by the suction nozzles 321b of the first holder 321 are placed in the recesses 323b formed in the second holder 323. When the recesses 323b of the second holder 323 hold the image sensors DUT, the suction of the first holder 321 on the image sensors DUT is released. The image sensors DUT inverted by the loader use inverting device 32 in this way so that their light receiving surfaces RL face upward are supplied through the loader use YZ movement device 33 and the first or second buffers 41, 42 to the contact arm 43. Note that the loader use YZ movement device 33, before picking up the image sensors DUT inverted by the loader use inverting device 32, uses the camera 334 to obtain an image of a back surface of an image sensor DUT (imaging step). That image information is processed by the image processing system 90 to identify the device type of the image sensor DUT. Further, at the time of movement by the loader use YZ movement device 33, the spraying nozzle 34 sprays nitrogen gas toward the image sensors DUT to clean the light receiving surfaces RL of the image sensors DUT On the other hand, after transferring the inverted image sensors DUT to the loader use YZ movement device 33, the loader use inverting device 32 drives the air cylinder 324 in a direction causing the piston rod 324a to retract, rotates the rotation mechanism 322 −180°, and thereby prepares for the inversion of the next image sensors DUT by returning the first holder 321 to the initial state shown in FIG. 6A. The system brings the four image sensors DUT supplied through the buffers 41, 42 simultaneously into contact with the four contacts 61 of the test head 60 by the contact arm 43, emits light to the light receiving surfaces RL of the image sensors 61 from the emission parts 81 of the light source 80, and, while doing so, inputs and outputs electrical signals through the contacts 61 and input/output terminals HE between the tester 20 and the image sensors DUT so as to test if the amounts of light received by the image sensors DUT are constant and other optical properties of the image sensors DUT (test step). In this test, the tester 70 inputs electrical signals to the image sensors DUT in accordance with an input pattern of electrical signals corresponding to the device type of the image sensors DUT identified by the above-mentioned image processing system 90. Similarly, in this test, the light source 80 emits light to the light receiving surfaces RL of the image sensors DUT in accordance with an emission pattern corresponding to the identified device type of the image sensors DUT. The image sensors DUT finished being tested by the test head 60 are moved by the first or second buffer 41, 42 and unloader use YZ movement device 51 to the unloader use inverting device 52. Next, the unloader use inverting device 52 picks up the image sensors DUT by suction at the first holder 521, uses the rotation mechanism 522 to rotate the first holder 521 by 180°, places the sensors in the second holder 523, then releases the suction so as thereby to invert the tested image sensors DUT so that their light receiving surfaces RL face upward (second inversion step). Next, the unloader use XYZ movements device 53 moves the inverted image sensors DUT to the sensor stacker 20, sorts them in the classification tray stackers 22 in accordance with the test results, and unloads the tested image sensors DUT. When sorting them in the classification tray stackers 22, in addition to the test results, the device type of the image sensor DUT identified by the above-mentioned image processing system 90 is also considered. On the other hand, the loader use inverting device 52 finishing transferring the inverted image sensors DUT to the unloader use YZ movement device 53 rotates the rotation mechanism 522 by −180° to prepare for the inversion of the next image sensors DUT by returning the first holder 521 to its initial state (see FIG. GA). As explained above, the image sensor test system according to the present embodiment inverts the image sensors DUT in the state with their light receiving surfaces RL facing upward by the loader use inverting device 32 so that their light receiving surfaces RL face downward, brings the inverted image sensors DUT into contact with the contacts 61 of the test head 60 by the contact arm 43 to test their optical properties, then inverts the tested image sensors DUT by the unloader use inverting device 52 to make their light receiving surfaces face upward for unloading. Due to this, the image sensors can be tested in the state with their light receiving surfaces RL facing downward and the light receiving surfaces RL can be prevented from being covered by dust, so high accuracy tests can be performed. Further, since the image sensors DUT can be tested in the state with their light receiving surfaces RL facing downward, it is possible to provide a light source 80 under the image sensors DUT separate from the handler 10, so the design freedom of the handler 10 and light source 80 is greatly improved and increases in the number of simultaneous measurements can be easily handled. Further, since the handler 10 and the light source 80 are separated, space and wiring for the light source in the handler 10 become unnecessary and, compared with the case of the handler 10 itself being provided with a light source, the structures of both the handler 10 and the light source 80 can be simplified. Incidentally, in the above-mentioned embodiment, the case of the test head 60 being provided with tour contacts 61 and simultaneously measuring four devices was explained, but the present invention is not particularly limited in the number of simultaneous measurements. The number of simultaneous measurements can be set in accordance with need. In particular, in the present invention, the greater the number of simultaneous measurements, the more remarkable the above-mentioned effects distinctive to the present invention. Note that the above explained embodiment was explained to facilitate understanding of the present invention and was not described to limit the present invention. Therefore, the elements disclosed in the above-mentioned embodiment include all design modifications and equivalents falling under the technical scope of the present invention. For example, in the above-mentioned embodiment, the image sensor test system 10 was explained as testing image sensors DUT of the type with input/output terminals HD led out in the same directions as the light receiving surfaces RL, but the present invention is not particularly limited to this. For example, it may also test sensors of the type as shown in FIG. 10 with the input/output terminals HE led out from the sides or sensors of the type as shown in FIG. 10B with the input/output terminals HD led out from the opposite sides from the light receiving surfaces RL. Note that the sensors of the type shown in FIG. 10B structurally cannot be brought into direct contact with the contacts at the time of testing, so it is necessary to provide the contact arm with upper contacts around the suction pads and use these upper contacts to indirectly electrically connect the input/output terminals of the image sensors and the contact pins of the contacts. Further, in the above-mentioned specific example, when desiring to store the tested inverted state image sensors in the inverted state in the classification tray stackers 22, it is possible to configure the system to additionally provide a conveyance path bypassing the unloader use inverting device 52. In this case, the advantage is obtained that the up-down orientation condition for storing the image sensors in the classification tray stackers 22 can be freely selected. Further, when the image sensors may be stored in the inverted state, it is possible to configure the system to omit the unloader use inverting device 52. Further, in the above explained embodiment, the explanation was given using a specific example of image sensors as the devices under test, but a system may also be configured to provide the above-mentioned loader use inverting device 32 when it is necessary to invert electronic devices other than image sensors stored in a supply tray stacker 21 at the contacts 61. Further, it is also possible to configure a system to provide the above-mentioned unloader use inverting device 52 when desiring to invert the inverted state electronic devices to their original states. Further, in the case of the electronic devices, the light source 90 is unnecessary. According to this, even it the up-down orientation of the input/output terminals HB of the electronic devices carried on the supply tray stacker 21 differs from that of the contacts, testing is possible without problem. As a result, a test system able to handle various types of electronic devices can be realized.

<SOH> TECHNICAL FIELD <EOH>The present invention relates to an image sensor test system and electronic device test system provided with a function of inverting electronic devices under test for testing. In particular, the present invention relates to an image sensor test system for inverting CCD sensors or CMOS sensors or other image sensors, bringing the input/output terminals of the image sensors into electrical contact with contacts of a test head, emitting light to light receiving surface of the image sensors from a light source, and, while doing so, inputting and outputting electrical signals with that image sensors so as to test the optical properties of the image sensors.

<SOH> BRIEF DESCRIPTION OF THE DRAWINGS <EOH>FIG. 1A is a plan view of an image sensor to be tested by an image sensor test system of a first embodiment of the present invention. FIG. 1B is a sectional view of the image sensor along the line I-I of FIG. TA. FIG. 2 is a schematic plan view of an image sensor test system according to an embodiment of the present invention. FIG. 3 is a sectional view of the image sensor test system along the line II-II of FIG. 2 . FIG. 4 is a perspective view of a loader use inverting device of an image sensor test system according to an embodiment of the present invention. FIG. 5A is a plan view of the loader use inverting device shown in FIG. 4 . FIG. 5B is aside view of the loader use inverting device shown in FIG. 4 . FIG. 6A is a side schematic view for explaining the operation of the loader use inverting device shown in FIG. 4 and shows the state before inversion. FIG. 6B is a side schematic view for explaining the operation of the loader use inverting device shown in FIG. 4 and shows the state after inversion. FIG. 7 is a view of the state of identification of the type or image sensor in an image sensor test system according to an embodiment of the present invention. FIG. 8 is a block diagram showing the system configuration for identifying the test of an image sensor in an image sensor test system according to an embodiment of the present invention. FIG. 9 is a schematic sectional view of a tester of an image sensor test system according to an embodiment of the present invention. FIG. 10A is a sectional view of an image sensor of a type with input/output terminals led out from the sides with respect to the light receiving surface. FIG. 10B is a sectional view of an image sensor of a type with input/output terminals led out from the opposite side from the light receiving surface. detailed-description description="Detailed Description" end="lead"?

20061005

20090120

20070906

62723.0

G03G1510

ISLA, RICHARD

IMAGE SENSOR TEST SYSTEM

UNDISCOUNTED

ACCEPTED

G03G

ACCEPTED

NEISSERIA GONORRHOEAE DETECTION

A method for determining whether a human individual is or has been infected with Neisseria gonorrhoeae, is provided. The method detects a Neisseria gonorrhoeae, porA nucleic acid fragment obtained from a biological sample. The method includes subjecting the biological sample to nucleic acid sequence amplification using primers having respective nucleotide sequences according to SEQ ID NO:1 and SEQ ID NO:2, to thereby produce a porA Neisseria gonorrhoeae, amplification product. The amplification product is detected by fluorescence resonance energy transfer using oligonucleotides having respective nucleotide sequences according to SEQ ID NO:3 which has a donor fluorophore and SEQ ID NO:4, which has an acceptor fluorophore.

1-23. (canceled) 24. A method of determining whether an individual is or has been infected with Neisseria gonorrhoeae, said method including the step of using one or more oligonucleotides to detect said isolated porA nucleic acid of Neisseria gonorrhoeae, if present in a biological sample obtained from said individual, a presence of said porA nucleic acid indicating that said individual is or has been infected with Neisseria gonorrhoeae, wherein said one or more oligonucleotides are not capable of hybridizing to a porA nucleic acid of Neisseria meningitidis sufficiently to enable detection of said porA nucleic acid of Neisseria meningitidis if present in said biological sample. 25. The method of claim 24, wherein said method includes the step of distinguishing said isolated porA nucleic acid of Neisseria gonorrhoeae from a porA nucleic of Neisseria meningitidis present in said biological sample. 26. The method of claim 25, wherein said porA nucleic acid of Neisseria gonorrhoeae is distinguished from another Neisseria species other than N. meningitidis. 27. The method of claim 24, including the step of subjecting the biological sample to nucleic acid sequence amplification under conditions which facilitate amplification of said isolated porA nucleic acid of Neisseria gonorrhoeae to produce an amplification product. 28. The method of claim 27, wherein the amplification product corresponds to a fragment of a Neisseria gonorrhoeae porA pseudogene. 29. The method of claim 28, wherein nucleic acid sequence amplification is performed under conditions which facilitate amplification of said isolated porA nucleic acid of Neisseria gonorrhoeae to a detectable level but which do not facilitate amplification of said porA nucleic of N. meningitidis to a detectable level. 30. The method of claim 29, wherein nucleic acid sequence amplification is performed using one or more PCR primers having a nucleotide sequence selected from the group consisting of SEQ ID NO:1 and SEQ ID NO:2. 31. The method of claim 27, wherein said one or more oligonucleotides comprise a probe for detecting said amplification product by probe hybridization. 32. The method of claim 31, wherein the probe is has a nucleotide sequence selected from the group consisting of SEQ ID NO:3; SEQ ID NO:4; SEQ ID NO:5; SEQ ID NO:6; SEQ ID NO:7; SEQ ID NO:8; SEQ ID NO:9. 33. The method of claim 32, wherein the probe is has a nucleotide sequence selected from the group consisting of SEQ ID NO:3 and SEQ ID NO:4. 34. The method of claim 31, wherein detection of said amplification product is performed using fluorescence resonance energy transfer (FRET). 35. A method, of determining whether a human individual is or has been infected with Neisseria gonorrhoeae, said method including the steps of; (i) subjecting a biological sample obtained from said human individual to nucleic acid sequence amplification using primers having respective nucleotide sequences according to SEQ ID NO:1 and SEQ ID NO:2, to produce a porA Neisseria gonorrhoeae amplification product from a Neisseria gonorrhoeae porA nucleic acid if present in said biological sample; and (ii) detecting said amplification product, if present, by probe hybridization and fluorescence resonance energy transfer (FRET) using oligonucleotides having respective nucleotide sequences according to SEQ ID NO:3 having a donor fluorophore and SEQ ID NO:4 having an acceptor fluorophore, whereby a presence of said porA amplification product indicates that said individual is or has been infected with Neisseria gonorrhoeae. 36. An oligonucleotide which is capable of hybridizing to a porA nucleic acid of Neisseria gonorrhoeae sufficiently to enable detection of said porA nucleic acid, but which is not capable of hybridizing to a porA nucleic acid of Neisseria meningitidis sufficiently to enable detection of said porA nucleic acid of Neisseria meningitidis. 37. The oligonucleotide of claim 35, wherein said oligonucleotide is not capable, of hybridizing to a porA nucleic acid of another Neisseria species other than N. meningitidis. 38. The oligonucleotide of claim 37 having a nucleotide sequence selected from the group consisting of SEQ ID NO:3; SEQ ID NO:4; SEQ ID NO:5; SEQ ID NO:6; SEQ ID NO:7; SEQ ID NO:8; SEQ ID NO:9. 39. The oligonucleotide of claim 38 having a nucleotide sequence selected from the group consisting of SEQ ID NO:3 and SEQ ID NO:4. 40. A kit for detecting a porA nucleic acid of Neisseria gonorrhoeae, said kit comprising one or more oligonucleotides according to claim 36 together with a DNA polymerase and/or one or more detection reagents. 41. The kit of claim 40, wherein the one or more oligonucleotides have a nucleotide sequence selected from the group consisting of SEQ ID NO:3; SEQ ID NO:4; SEQ ID NO:5; SEQ ID NO:6; SEQ ID NO:7; SEQ ID NO:8; SEQ ID NO:9. 42. The kit of claim 41, wherein the one or more oligonucleotides have a nucleotide sequence selected from the group consisting of SEQ ID NO:3 and SEQ ID NO:4. 43. The kit of claim 40, further comprising one or more primers that facilitate amplification of an Neisseria gonorrhoeae, porA nucleic acid. 44. The kit of claim 43, wherein the one or more primers have a nucleotide sequence selected from the group consisting of SEQ ID NO:1 and SEQ ID NO:2. 45. A nucleic acid array comprising one or more oligonucleotides according to claim 35, immobilized, coupled, bound, impregnated or otherwise in communication with a substrate. 46. The nucleic acid array of claim 45, wherein the one or more oligonucleotides have a nucleotide sequence selected from the group consisting of SEQ ID NO:3; SEQ ID NO:4; SEQ ID NO:5; SEQ ID NO:6; SEQ ID NO:7; SEQ ID NO:8; SEQ ID NO:9. 47. The nucleic acid array of claim 46, wherein the one or more oligonucleotides have a nucleotide sequence selected from the group consisting of SEQ ID NO:3 and SEQ ID NO:4.

FIELD OF THE INVENTION THIS INVENTION relates to detection of the bacterium Neisseria gonorrhoeae, more particularly to detection of bacterial nucleic acids. This invention particularly relates to the detection of amplified fragments of a porA gene of Neisseria gonorrhoeae, for determining, whether the bacterium is present in a biological sample obtained from an individual, typically for the proposes of clinical diagnosis. BACKGROUND OF THE INVENTION Neisseria gonorrhoeae, is a gram-negative diplococcal bacterial pathogen which is the causative organism of the sexually transmitted disease (STD) known as gonorrhoea. Although gonorrhoea is an ancient disease first described by Galen in AD 150, it is still a major STD of humans. Failure to detect and treat Neisseria gonorrhoeae infection can allow the disease to progress to a serious systemic infection that affects the heart, joints, meninges, eyes and pharynx. Thus, early definitive diagnosis can assist treatment of the disease and prevent the serious complications that can arise as a result of this bacterial infection. Although polymerase chain reaction (PCR) is the method of choice for routine detection of Neisseria gonorrhoeae, PCR has limitations and bacterial isolation has remained the gold standard for definitive diagnosis. This is largely because N. gonorrhoeae shares much sequence homology with other Neisseria species, including N. meningitidis, and in addition, contains many non-conserved sequences (Palmer et al., 2003, J. Clin. Microbiol. 41 835-7). Thus, there is a potential for both false-positive and false-negative results to occur when using PCR for routine detection of N. gonorrhoeae. In both situations the consequences may be significant. From a public health perspective, false-negative results may allow unchecked spread of the disease whereas false-positive results can have considerable social ramifications for patients. The Roche Cobas Amplicor system (Roche Diagnostics, Australia) is a PCR assay widely used for the detection of N. gonorrhoeae. Its appeal lies in its ability to simultaneously detect N. gonorrhoeae, Chlamydia trachomatis and the presence of inhibiting substances, while also carrying United States Food and Drug Administration (FDA) approval. However, the Cobas Amplicor system does have limitations. Most, notably, its N. gonorrhoeae assay is known to cross react with some strains of commensal Neisseria species, including N. subflava, N. cinerea, N. flavescens, N. lactamica and N. sicca (Palmer et al., 2003, supra; Farrell, 1999, J. Clin. Microbiol. 37 386-90). Consequently, there is a need to use a second PCR assay to confirm Cobas Amplicor positive results. In response, clinical laboratories have adopted in-house confirmatory assays. To date, the most common target for in-house confirmatory tests has been the cryptic plasmid (cppB) gene of N. gonorrhoeae, with several such protocols having been described (Ho et al., 1992, J. Clin Pathol. 45 439-442; Farrell, 19995 supra; Whiley et al., 2002, Diagn. Microbiol. Infect. Dis. 42 85-9; Tabrizi et al., 2004, Sex. Trans. Infect 80 68-71). In particular, a LightCycler based cppB PCR (cppB-LC) assay has been developed for conformation of Cobas N. gonorrhoeae positive specimens (Whiley et al., 2002, supra). However, serious concerns have now been raised over the sensitivity and specificity of N. gonorrhoeae assays targeting the cppB gene. Studies conducted in both the United Kingdom and Australia have identified N. gonorrhoeae isolates lacking the cppB gene (Palmer et al. 2003, supra, Ottawa; A cluster of culture-positive, but PCR false negative infections with Neisseria gonorrhoeae. Tapsall et al., Abstract 0129. 15th Biennial Congress of the International Society for Sexually Transmitted Diseases Research ISSTDR). Therefore, laboratories targeting this gene run the risk of false-negative results. In addition, the cppB gene could be present in commensal Neisseria strains, including N. cinerea, and so could also produce false-positive results (Palmer et al. 2003, supra). Cross-reaction is a significant problem for gonococcal nucleic acid-based diagnostic testing and horizontal genetic exchange in the Neisseria genus is the major source of these cross-reactions (Johnson et al., 2002, MMWR Recomm. Rep 18 1-38). Furthermore, gonococcal tests are used on non-sterile sites and other Neisseria strains may frequently be found in such sites. PCR detection of the porA gene has been used to detect. Neisseria meningitidis (Glustein et al., 1999, Molecular Diagnosis 4 233-9), partly due to an assumption that is gene is absent in commensal Neisseria (Feavers & Maiden, 1998, Mol. Microbiol. 30 647-656). Furthermore, in such assays, cross-reaction (or the potential for cross-reaction) is not a significant threat as these tests are used on sterile sites, including blood and CSF. The only other Neisseria species where a porA sequence has been identified is N. gonorrhoeae, which has a porA pseudogene of considerable sequence similarity to the N. meningitidis porA gene (Feavers & Maiden, 1998, supra). However, it is not clear whether this pseudogene is present in all strains of N. gonorrhoeae, nor has its absence in commensal strains been verified. SUMMARY OF THE INVENTION Notwithstanding the fact that the N. gonorrhoeae porA pseudogene is an unlikely target for nucleic acid-based detection of N. gonorrhoeae and, more particularly for distinguishing between N. gonorrhoeae and N. meningitidis, and might not be present ubiquitously among N. gonorrhoeae isolates and strains or absent in commensal strains, the present inventors have developed a surprisingly sensitive and reproducible nucleic acid-based detection method using the N. gonorrhoeae porA pseudogene as a target. The present invention is therefore broadly directed to an method of determining whether an individual is or has been infected with Neisseria gonorrhoeae, which method utilizes a porA pseudogene or porA nucleic acid derived therefrom, as an indicator of infection. The present, invention is also broadly directed to one or more oligonucleotides which facilitate detection of a Neisseria gonorrhoeae, porA gene or porA nucleic acid. In a first aspect the invention provides a method of determining whether an individual is or has been infected with Neisseria gonorrhoeae, said method including the step of detecting an isolated porA nucleic acid of Neisseria gonorrhoeae, if present in a biological sample obtained from said individual, a presence of said porA nucleic acid indicating that said individual is or has been infected with Neisseria gonorrhoeae. Preferably, the method includes the step of subjecting a nucleic acid sample to nucleic acid sequence amplification under conditions which facilitate amplification of said isolated porA nucleic acid to a detectable level. In a second aspect the invention provides a method of determining whether an individual is or has been infected with Neisseria gonorrhoeae, said method including the step of selectively detecting or distinguishing an isolated porA nucleic acid of Neisseria gonorrhoeae, from a porA nucleic of another Neisseria species if present in said biological sample obtained from said individual, a presence of said isolated porA nucleic acid indicating mat said individual is or has been infected with Neisseria gonorrhoeae. Preferably, the method includes the step of subjecting a nucleic acid sample to nucleic acid sequence amplification under conditions which facilitate amplification of said isolated porA nucleic acid to a detectable level but which do not facilitate amplification of said porA nucleic of said another Neisseria species to a detectable level. Preferably, said another Neisseria species is N. meningitidis. In a preferred embodiment the invention provides a method of determining whether a human individual is or has been infected with Neisseria gonorrhoeae said method inducing the steps of: (i) subjecting a biological sample obtained from said human individual to nucleic acid sequence amplification to selectively produce a porA Neisseria gonorrhoeae, amplification product from a Neisseria gonorrhoeae, porA nucleic acid if present in said biological sample; and (ii) detecting said amplification product, if present, by probe hybridization whereby a presence of said porA amplification product indicates that said individual is or has been infected with Neisseria gonorrhoeae. In a third aspect, the invention provides an oligonucleotide which is capable of hybridizing to a porA nucleic acid of Neisseria gonorrhoeae, sufficiently to enable detection of said porA nucleic acid, but which is not capable of hybridizing to a porA nucleic acid of another Neisseria species sufficiently to enable detection of said porA nucleic acid of said another Neisseria species. Preferably, said another Neisseria species is N. meningitidis. In preferred embodiments, said oligonucleotide comprises a nucleotide sequence as set forth in Table 1 and FIG. 1 (SEQ ID NOS:3-9). In a fourth, aspect, the invention provides a kit comprising one or more oligonucleotides according to the third aspect together with a DMA polymerase and/or one or more detection reagents. In a fifth aspect the invention provides a nucleic acid array comprising an oligonucleotide according to the second aspect, immobilized, coupled, impregnated or otherwise in communication with a substrate. It will be appreciated that the invention provides a method and oligonucleotide mat facilitate detection of a porA nucleic acid of Neisseria gonorrhoeae. Preferably the porA nucleic acid corresponds to a fragment of a porA pseudogene of Neisseria gonorrhoeae. More preferably, according to tins embodiment the porA nucleic acid corresponds to a fragment of a porA pseudogene of Neisseria gonorrhoeae, which fragment has a nucleotide sequence distinct from a fragment of a porA gene or pseudogene of another Neisseria species. In a particularly preferred embodiment, the porA nucleic acid of Neisseria gonorrhoeae, comprises a nucleotide sequence to which an oligonucleotide is capable of annealing sufficient to enable detection of said porA nucleic acid. Suitably, said nucleotide sequence is not present in, or has one or more nucleotides different to, a nucleotide sequence of a porA nucleic acid of another Neisseria species, such that said oligonucleotide is not capable of hybridizing to said porA nucleic acid of said another Neisseria species sufficient to facilitate detection of said porA nucleic acid of said another Neisseria species. Preferably, said another Neisseria species is N. meningitidis. In a particularly advantageous embodiment, the method and oligonucleotide of the invention facilitate detection of a porA nucleic acid feat may be present in each, of a plurality of isolates, strains, allelic variants or sub-species of Neisseria gonorrhoeae. Throughout tins specification, unless otherwise indicated, “comprise”, “comprises” and “comprising” are used inclusively rather than exclusively, so that a stated integer or group of integers may include one or more other non-stated integers or groups of integers. BRIEF DESCRIPTION OP THE FIGURES FIG. 1 List of preferred oligonucleotide primer sequences (AS=antisense) and nucleotide sequence of N. gonorrhoeae porA pseudogene. Bolded residues indicate (5′ to 3′) NG-pap-F (forward) primer annealing site; NG-pap-p1 probe hybridization site; NG-pap-p2 probe hybridization site; and KG-pap-R (reverse) primer annealing site. The expected amplification product size is 132 bp. Shaded residues are those which are non-identical with the corresponding N. meningitidis porA sequence. Sequence identifiers as follows: NG-pap-F (forward) primer sequence: (SEQ ID NO:1); NG-pap-R (reverse) primer sequence (SEQ ID NO:2); NG-pap-p1 probe (SEQ ID NO:3); NG-pap-p2 probe sequence (SEQ ID NO:4); NG-pap-p3 probe sequence (SEQ ID NO:5); NG-pap-p4 probe sequence (SEQ ID NO:6); NG-pap-p5 probe sequence (SEQ ID NO:7); NG-pap-p6 probe sequence (SEQ ID NO:8); NG-pap-p7 probe sequence (SEQ ID NO:9); N. gonorrhoeae porA pseudogene sequence (SEQ ID NO: 10); DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention is directed to improving nucleic acid-based detection of N. gonorrhoeae. To this end the present inventors have identified an alternative PCR target sequence on the N. gonorrhoeae genome, namely the porA pseudogene, which has never before been used as a target for N. gonorrhoeae detection and unexpectedly offers drastically improved clinical, sensitivity and specificity for the detection of N. gonorrhoeae when compared with other PCR assays described to date. More particularly, the present inventors have developed a new N. gonorrhoeae LightCycler™ assay targeting the N. gonorrhoeae porA pseudogene. Importantly, the Neisseria porA gene is shown to be present in all N. gonorrhoeae samples and isolates tested bat absent in commensal Neisseria species. Therefore, the selection of this gene target eliminates or at least reduces the potential for cross-reaction with commensal Neisseria species. Differences existing in porA sequences between N. gonorrhoeae and N. meningitidis have also been exploited to develop oligonucleotides that enable specific PCR amplification and detection of N. gonorrhoeae-derived porA nucleic acids only. A particular difficulty overcome by the present invention is that there are only a few, small sections of porA sequence with sufficient difference between N. gonorrhoeae and N. meningitidis to develop a specific gonococcal assay. Too few mismatches between amplification primers and contaminating DNA, namely meningococcal porA DNA, will cause the assay to cross-react. Too many mismatches between primers and their respective targets may decrease the amplification efficiency of PCR amplification of the gonococcal target porA sequence. The oligonucleotide primers of the invention have sufficient mismatches so as to make the assay specific for gonococcal porA DNA, even when contaminated with relatively high concentrations of meningococcal DNA (approximately 0.5 μg per reaction). The present invention therefore provides a method for detecting an isolated porA nucleic acid of Neisseria gonorrhoeae, in a biological sample and one or more oligonucleotides, which facilitate amplification and/or detection of said porA nucleic acid. For the purposes of this invention, by “isolated” is meant material that has been removed from its natural state or otherwise been subjected to human manipulation. Isolated material may be substantially or essentially free from components that normally accompany it in its natural state, or may be manipulated so as to be in an artificial state together with components that normally accompany it in its natural state. Isolated material may be in native, chemical synthetic or recombinant form. As used herein, “nucleic acid” includes and encompasses DNA, RNA and PNA-RNA hybrids. DNA includes single-stranded and double-stranded genomic DNA and cDNA as are well understood in the art. RNA includes single-stranded and double-stranded unprocessed RNA, mRNA and tRNA. It will be appreciated that by “porA nucleic acid” is meant a nucleic acid which corresponds to at least a fragment or region of a porA gene or pseudogene. As used herein, a “gene” is a discrete structural unit of a genome which may comprise one or more elements such as an amino acid coding region typically present in one or more cistrons, an operator, a promoter, a terminator and/or any other regulatory nucleotide sequence(s). As used herein a “pseudogene” is an inactive unit, region or sequence of a genome which has a similar sequence to a known functional gene. Typically, because of this sequence similarity, pseudogenes are normally considered to be evolutionary relatives to normally functioning; genes. In N. gonorrhoeae, porA is a pseudogene while in N. meningitidis porA is a gene. By “corresponds to” or “corresponding to” in tins context in meant that the porA nucleic acid comprises a nucleotide sequence which is present in an porA pseudogene, or is complementary to a nucleotide sequence present in a porA pseudogene, or is at least 80%, preferably at least 85%, more preferably at least 90% or even more preferably at least 95%, 96%, 97%, 98% or 99% identical to either of these. In a particularly preferred embodiment the porA nucleic acid corresponds to a 132 bp fragment of a porA pseudogene. In particular aspects, the invention provides one or more oligonucleotides and/or methods of using same for facilitating nucleic acid sequence amplification and/or detection of a porA nucleic acid. As used herein, an “oligonucleotide” is a single- or double-stranded nucleic acid having no more than one hundred (100) nucleotides (bases) or nucleotide pairs (base pairs). A “polynucleotide”1 has more than one hundred (100) nucleotides or nucleotide pairs. In the particular context of nucleic acid sequence amplification, an oligonucleotide of the invention may be in the form of a primer. As used herein, a “primer” is a single-stranded oligonucleotide which is capable of hybridizing to a nucleic acid “template” and being extended in a template-dependent fashion by the action of a suitable DNA polymerase such as Taq polymerase, RNA-dependent DNA polymerase or Sequenase™. Typically, a primer may have at least twelve, fifteen, twenty, twenty-five, thirty, thirty five or forty but no more than fifty contiguous nucleotide bases. It will be appreciated that the primers described herein have been designed according to selected criteria to maximize detection sensitivity and specificity. Suitably, primers of the invention are designed to be capable of annealing to a nucleotide sequence of a Neisseria gonorrhoeae, porA nucleic acid that is not present in, or has one or more nucleotides different to, a nucleotide sequence of a porA nucleic acid of another Neisseria species, such that said oligonucleotide is not capable of annealing to said porA nucleic acid of said another Neisseria species sufficient to facilitate detection of said porA nucleic acid of said another Neisseria species. Preferably, said another Neisseria species is N. meningitidis. It will also be appreciated that the present invention is predicated, in part, on the observation that other, commensal Neisseria species such as N. subflava, N. cinerea, N. flavescens, N. lactamica and N. sicca do not have a porA pseudogene. In one particularly advantageous embodiment, primers of the invention are designed to facilitate detection of a porA nucleic acid of a plurality of isolates, strains, allelic variants or sub-species of Neisseria gonorrhoeae. Accordingly, the present inventors have identified nucleotide sequences in a porA gene of Neisseria gonorrhoeae, which are conserved within a plurality of isolates of this pathogenic organism, which sequences are not present in, or are sufficiently different to, respective nucleotide sequences in a porA pseudogene of Neisseria meningitidis. This has enabled the present inventors to design primers that facilitate specific, sensitive and broad-spectrum amplification of Neisseria gonorrhoeae, porA nucleic acids while avoiding amplification of a porA nucleic acid of said another Neisseria species, or at least minimizing amplification thereof to an undetectable level. Particular examples of primers according to the invention are provided in FIG. 1 and Table 1 (SEQ ID NOS: 1 and 2). It will be appreciated from comparing the primer sequences of FIG. 1 (SEQ ID NOS:1 and 2), the N. gonorrhoeae, porA pseudogene nucleotide sequence set forth in FIG. 1 (SEQ ID NO: 10) and the corresponding published N. meningitidis porA nucleotide sequence, that variations in primer sequence are readily achievable while maintaining the specificity necessary for selectively amplifying a N. gonorrhoeae, porA sequence. In a preferred embodiment the invention contemplates detection of a porA nucleic acid or fragment thereof by nucleic acid sequence amplification and subsequent detection of a porA amplification product Nucleic acid amplification techniques are well known to the skilled addressee, and include polymerase chain reaction (PCR) and ligase chain reaction (LCR) as for example described in Chapter 15 of Ausubel et al. CURRENT PROTOCOLS IN MOLECULAR BIOLOGY (John Wiley & Sons NY, 1995-1999); strand displacement amplification (SDA) as for example described in U.S. Pat. No. 5,422,252; roiling circle replication (RCR) as for example described in Liu et al., 1996, J. Am. Chem. Soc. 118 1387 and International application WO 92/01813 and by Lizardi et al., in International Application WO 97/19193; nucleic acid sequence-based amplification (NASBA) as for example described by Sooknanan et al., 1994, Biotechniques 17 1077; Q-β replicase amplification as for example described by Tyagi et al., 1996, Proc. Natl. Acad. Sci. USA 93 5395 and helicase-dependent amplification as described in International Publication WO2004/02025. The abovementioned are examples of nucleic acid sequence amplification techniques but are not presented as an exhaustive list of techniques. Persons skilled in the art will, be well aware of a variety of other applicable techniques as well as variations and modifications to the techniques described herein. For example, the invention contemplates use of particular techniques that facilitate quantification of nucleic acid sequence amplification products such as by “competitive PCR”, or techniques such as “Real-Time” PCR amplification such as described in Whiley et al., 2002, supra. Preferably, the nucleic acid sequence amplification technique is PCR. As used herein, an “amplification product” is a nucleic acid generated by a nucleic acid sequence amplification technique as hereinbefore described. In a particularly preferred embodiment the method produces a single 132 bp porA amplification product. As used herein, “hybridization”, “hybridize” and “hybridizing” refers to formation of a hybrid nucleic acid through base-pairing between complementary or at least partially complementary nucleotide sequences under defined conditions, as is well known in the art. Normal base-pairing occurs through formation of hydrogen bonds between complementary A and T or U bases, and between G and C bases. It will also be appreciated that base-pairing may occur between various derivatives of purines (G and A) and pyrrolidines (C, T and U). Purine derivatives include inosine, methylinosine and methyladenosines. Pyrimidine derivatives include sulfur-containing pyrimidines such as thiouridine and methylated pyrimidines such as methylcytosine. For a detailed discussion of the factors that generally affect nucleic acid hybridization, the skilled addressee is directed to Chapter 2 of CURRENT PROTOCOLS IN MOLECULAR BIOLOGY, supra. More specifically, the terms “anneal” and “annealing” are used in the context of primer hybridisation to a nucleic acid template for a subsequent primer extension reaction, such as occurs during nucleic acid sequence amplification or dideoxy nucleotide sequencing, for example. For a discussion of the factors that affect annealing of PCR primers, the skilled addressee is directed to Chapter 15 of CURRENT PROTOCOLS IN MOLECULAR BIOLOGY Eds Ausubel et al. (John Wiley & Sons NY 1995-1999). The invention provides detection of a porA nucleic acid of Neisseria gonorrhoeae, in a biological sample as an indication or the presence of a Neisseria gonorrhoeae, in an individual from which the biological sample has been derived or obtained, or as an indication of a past Neisseria gonorrhoeae, infection of said individual. Preferably, a porA nucleic acid amplification product, which amplification product is detected by one or more methods as well understood in the art. Detection of amplification products may be achieved by detection of a probe hybridized to an amplification product, by direct visualization of amplification products by way of agarose gel electrophoresis, nucleotide sequencing of amplification products or by detection of fluorescently-labeled amplification products. As used herein, a “probe” is a single- or double-stranded oligonucleotide or polynucleotide, one and/or the other strand of which is capable of hybridizing to another nucleic acid, to thereby form a “hybrid” nucleic acid Probes and/or primers of the invention may be labeled, for example, with biotin or digoxigenin, with fluorochromes or donor fluorophores such as FITC, TRITC, Texas Red, TET, FAM6, HEX, ROX or Oregon Green, acceptor fluorophores such as L-Red640, enzymes such as horseradish peroxidase (HRP) or alkaline phosphatase (AP) or with radionuclides such as 125I, 32P, 33P or 35S to assist detection of amplification products by techniques are well known in the art. Preferred embodiments of probes according to the present invention have respective nucleotide sequences set forth, in FIG. 1 and Table 2 (SEQ ID NOS:3-9). Particularly preferred embodiments of probes according to the present invention have respective nucleotide sequences set forth in SEQ ID NOS: 3 and 4. With regard to detection of fluorescently-labelled amplification products, this may be achieved using one or more primers that incorporate fluorescent labels as hereinbefore described. In another embodiment, detection may be performed by melting curve analysis using probes incorporating fluorescent labels that hybridize to amplification products in a sequence amplification reaction. A particular example is the use of Fluorescent Resonance Energy Transfer (FRET) probes to hybridize with amplification products in “real time” as amplification products are produced with each cycle of amplification. A FRET hybridization probe pair is designed to hybridize to adjacent regions on a target DNA. Each probe is labeled with a different marker dye. Interaction of the two dyes can only occur when both are bound to their target. Typically, the donor probe is labeled with a fluorophore (such as FITC, TRITC, Texas Red, TET, FAM6, HEX, ROX or Oregon Green) at the 3′ end and the acceptor probe is labelled with an acceptor fluorophore (such as LC-Red640, TAMRA or QSY dyes) at its 5′ end. During PCR, the two different oligonucleotide probes hybridize to adjacent regions of the target DNA such that the fluorophores, which are coupled to the oligonucleotides, are in close proximity in the hybrid structure. The donor fluorophore is excited by an external light source, then passes part of its excitation energy to the adjacent acceptor fluorophore. The excited acceptor fluorophore emits light at a different wavelength which can then be detected and measured. In yet another embodiment, the invention contemplates use of melting curve analysis whereby nucleic acid-intercalating dyes such as ethidium bromide (EtBr) or SYBR Green I bind amplification products and fluorescence emission by the intercalated complexes is detected. Melting curve analysis may advantageously be performed using an apparatus such as a LightCycler™, as for example described in Whiley et al., 2002, supra. In light of the foregoing, it will be apparent that the Neisseria gonorrhoeae, detection methods of the invention are ideally suited to assisting diagnosis of individuals that may have had, or currently have, a Neisseria gonorrhoeae, infection. Neisseria gonorrhoeae, is a primarily a pathogenic organism of humans, hence the present invention is particularly directed to detection of Neisseria gonorrhoeae, infection in human individuals. Suitably, said biological sample is a cervical, urethral, penile, anal, rectal, throat, saliva, fecal or urine sample, although without limitation thereto. Suitably, said biological sample includes one or more bacteria or nucleic acid(s) derived therefrom which may be in the form of DNA or RNA. Preferably, in order to minimize handling of said biological sample, genomic DNA is isolated from said biological sample according to the method of the invention. However, in principle, cDNA could be generated by reverse-transcribing isolated RNA as is well known in the art, as for example described in Chapter 15 of CURRENT PROTOCOLS IN MOLECULAR BIOLOGY, supra. Particularly for the purpose of clinical diagnosis, although, without limitation thereto, the invention provides a kit comprising one or more oligonucleotides such as a primer pair according to the third aspect of the invention, Said kit may further comprise other reagents such as a thermostable DNA polymerase, a porA nucleic acid probe, positive and/or negative nucleic acid control samples, molecular weight markers, detection reagents such as for colorimetric detection or fluorescence detection of amplification products and/or reaction vessels such as microtitre plates. It will also be appreciated that the method of the invention may be used alone or combined with other forms of diagnosis, such as bacterial culture tests or traditional diagnosis based on clinical symptoms, to improve the accuracy of diagnosis. In a preferred embodiment the invention provides a method of determining whether a human individual is or has been infected with Neisseria gonorrhoeae, said method including the steps of: (i) subjecting a biological sample obtained from said human individual to nucleic acid sequence amplification to selectively produce a porA Neisseria gonorrhoeae, amplification product from a Neisseria gonorrhoeae, porA nucleic acid if present in said biological sample; and (ii) detecting said amplification product, if present, by probe hybridization whereby a presence of said porA amplification product indicates that said individual is or has been infected with Neisseria gonorrhoeae. According to a particularly preferred form of this embodiment, real-time PCR detection is utilized at step (ii), by fluorescence resonance energy transfer (FRET) using an adjacent hybridization probe format. The preferred upstream oligonucleotide probe (NGpapP1; Table 1; SEQ ID NO:3) is labelled with a donor fluorophore, fluorescein, at the 3′ terminus, and the preferred downstream oligonucleotide probe (NGpapP2; Table 1; SEQ ID NO:4) is labelled with, an acceptor fluorophore. LC-Red640, at the 5′ terminus. Probe NGpapP2 (SEQ ID NO:4) is also phosphorylated at the 3′ terminus. It will be further appreciated that the present invention may be performed in conjunction with nucleic acid-based detection of other pathogenic organisms. In this regard, the invention contemplates nucleic acid array detection of a porA nucleic acid of Neisseria gonorrhoeae, wherein one or more other nucleic acids of other pathogenic organisms may be detected. A general discussion of this type of microarray approach to multi-pathogen detection is provided in Bryant et al., 2004, Lancet Infect. Dis, 4 100. It will be appreciated that the nucleic acid array may comprise an oligonucleotide according to the second aspect, immobilized, coupled, impregnated or otherwise in communication with a substrate. More generally, nucleic acid array technology has become well known in the art and examples of methods applicable to array technology are provided in Chapter 22 of CURRENT PROTOCOLS IN MOLECULAR, BIOLOGY Eds. Ausubel et al. (John Wiley & Sons NY USA 1995-2001). In certain embodiments, at least one address of the plurality includes a nucleic acid capture probe that hybridizes specifically to a member of a nucleic acid library, e.g., the sense or anti-sense strand. In one preferred embodiment, a subset of addresses of the plurality of addresses has a nucleic acid capture probe for a nucleic acid library member. Each address of the subset can include a capture probe that hybridizes to a different region of a library member. With respect to the present invention, a preferred array format comprises glass slides having an immobilized, ordered grid of a plurality of cDNA fragments. The array can have a density of at least man 10, 50, 100, 200, 500, 1,000, 2,000, or 10,000 or more addresses/cm, and ranges therebetween. The substrate may be a two-dimensional substrate such as a glass slide, a wafer (e.g., silica or plastic), a mass spectroscopy plate, or a three-dimensional substrate such as a gel pad. An array can be generated by various methods, e.g., by photolithographic methods (see, e.g., U.S. Pat. Nos. 5,143,854; 5,510,270; and 5,527,681), mechanical methods (e.g., directed-flow methods as described in U.S. Pat. No. 5,384,261), pin-based methods (e.g., as described in U.S. Pat. No. 5,288,514), and bead-based techniques (e.g., as described in PCT/US93/04145). So that the present invention can be readily understood and put into practical effect, reference is made to the following son-limiting examples. EXAMPLES Materials & Methods Patient Specimens A total of 282 clinical samples (46 cervical swabs, 12 urethral swabs and 224 urine specimens) from patients presenting for sexual health screen were used in this study. Given the low incidence of N. gonorrhoeae infection in our local population, the samples were selected to provide a large proportion of Cobas positive specimens. The patients comprised 178 females and 104 males and ranged in age from 13 to 70 years with a mean age of 26 years and a median age of 23 years. All 282 samples were tested by the NGpapLC assay and by a testing algorithm combining the Roche Cobas Amplicor assay and the cppB-LC assay. Using this algorithm, specimens, were initially tested by the Cobas Amplicor method. Any sample providing a positive N. gonorrhoeae result by the Cobas Amplicor assay was then tested by the cppB-LC assay for confirmation. Roche Cobas Amplicor Assay The urine and swab specimens were processed and tested on the Roche Cobas Amplicor System according to the manufacturer's instructions. Each specimen was simultaneously tested for N. gonorrhoeae, Chlamydia trachomatis and the presence of inhibiting substances. Result interpretation was performed using the criteria supplied by the manufacturer. Briefly, specimens providing as absorbance less than 0.2 were considered negative for N. gonorrhoeae whereas specimens providing an absorbance value of 0.2 or greater were considered positive. LightCycler Assays (NGpapLC and cppB-LC) A column extraction was used for both the NGpapLC and cppB-LC LightCycler assays. Nucleic acids were extracted from 0.2 ml of each specimen using the High Pure Viral Nucleic Acid kit (Roche Diagnostics, Australia), according to the manufacturer's instructions. Purified specimen DNA was eluted from the column in 50 μl of elation buffer (Roche Diagnostics, Australia). DNA extracts were stored at −20° C. until analysis. The NGpapLC assay comprised of one primer pair, one pair of hybridization probes and targeted the N. gonorrhoeae porA pseudogene. Amplification was performed using primers papF and papR (Table 1; Invitrogen, Australia), which produced a 132 bp PCR product dining the reaction. Real-time PCR detection was achieved by fluorescence resonance energy transfer (FRET) using an adjacent hybridization probe format. The upstream oligonucleotide probe (papP1; Table 1) was labelled with a donor fluorophore, fluorescein, at the 3′ terminus, and the downstream oligonucleotide probe (papP2; Table 1) was labelled with an acceptor fluorophore, LC-Red640, at the 5′ terminus (TIBMOLBIOL, Germany). Probe papP2 was also phosphorylated at the 3′ terminus. The LightCycler FastStart DMA Master Hybridization Probes kit (Roche Diagnostics, Australia) was used as the basis for the reaction mixture, employing a 20 μl volume in each reaction capillary. Briefly, capillaries were loaded with 2 μl of kit Master reagent (10×; Roche Diagnostics, Australia, reagent 1), 4 mM of MgCl2 (Roche Diagnostics, Australia, reagent 2), 0.4 μM of primer papF, 0.6 μM of primer papR, 0.2 μM of each hybridization probe and 5 μl of DNA extract. Each mix was made up to 20 μl using sterile PCR-grade water (Roche Diagnostics, Australia, reagent 3). Every test ran included a positive control and three no-target controls consisting of 15 μl of reaction mixture with 5 μl of extraction elution buffer. Amplification and detection was performed on the LightCycler (software version 5.32) using the following parameters: an initial denaturation step at 95° C. for 10 minutes followed by 55 cycles of denaturation at 95° C. for 10 seconds, primer and probe annealing at 55° C. for 10 seconds and extension at 72° C. for 20 seconds. The fluorescence response data were obtained during the annealing period and analysed with the channel settings F2/F1. Melting curve analysis was performed following PCR amplification. Briefly, the analysis was commenced at 40° C., and the temperature was raised to 95° C. at a rate of 0.2° C./s. The cppB-LC assay was performed as previously described (Whiley et al., 2002, supra) and utilized similar conditions to those of the NGpapLC assay. Briefly, the LightCycler FastStart DNA Master Hybridisation Probes kit (Roche Diagnostics, Australia) was used as the basis of the reaction mix. Each reaction capillary comprised a total reaction volume of 20 μl, which included two primers (HO1 @ 0.2 μM and HO2 @ 0.4 μM) and two hybridisation probes (0.2 μM each) targeting the N. gonorrhoeae cppB gene (Whiley et al., 2002, supra). Defection Limit The detection limits of the NGpapLC and cppB-LC assays were determined and compared by testing dilations of a suspension of a N. gonorrhoeae culture (ATCC49226) at 5×10E4 colony forming units/ml (cfu/ml). Serial 10-fold dilutions of this suspension were extracted and tested by both assays using the conditions described above. The detection limit of each assay was determined as the lowest concentration returning a positive reaction. Neisseria Panel A panel of Neisseria species was tested by both the NGpapLC and cppB-LC assays. This panel included 63 non-gonococcal Neisseria isolates, which were tested to determine false-positive cross-reactions. The species comprised N. meningitidis (38), N. subflava (12), N. sicca (6), N. elongata (3), N. mucosa (1), N. lactamica (3) and Branhamella catarrhalis (6), which is closely related to the Neisseria genus. In addition, 84 N. gonorrhoeae isolates were tested to determine if the primer and probe sequence targets of each assay were conserved. Six N. gonorrhoeae isolates were included that had previously tested negative by the cppB-LC assay. These six isolates were provided by Royal Darwin Hospital, Northern Territory. The remaining N. gonorrhoeae isolates were selected from different geographical locations throughout the state of Queensland to ensure a broad cross section of isolates. Nucleic acids were extracted from cultures of each isolate using the High Pure Viral Nucleic Acid kit (Roche Diagnostics, Australia), according to the manufacturer's instructions. Approximately 0.5 μg of bacterial DNA was added to each reaction. Non-Neisseria Panel—Common Human Pathogens and Normal Flora An additional panel of common human pathogens and normal flora was also used to further determine the specificity of the NGpapLC assay; Acinetobacter aranitratus ATCC 19606, Acinetobacter beautmanni ACM 686, Acinetobacter haemolyticus ACM 620, Acinetobacter johnsonii ACM 621, Acinetobacter junii ACM 617, Acinetobacter lwolfii ACM 664, Aeromonas hydrophilia ATCC 35654, Alcaligenes faecalis ATCC 35655, Bacillus amyloliquifaciens ATCC 3642, Bacillus brevis ATCC 37, Bacillus cereus ATCC 11778, Bacillus circulans ATCC 61, Bacillus coagulans ATCC 264, Bacillus firmus ATCC 31, Bacillus laterosporus ATCC 295, Bacillus licheniformis ATCC 127559, Bacillus macerans ATCC 401, Bacillus megaterium ATCC 2640, Bacillus mycoides ATCC 28, Bacillus polymyxa ATCC 35, Bacillus pumulis ATCC 433, Bacillus sphaericus ATCC 4525, Bacillus subtillus ATCC 11774, Bacillus thuringiensis ATCC 453, Bacteroides distasonis ATCC 8503, Bacteroides gingivalis ATCC 33277, Bacteroides vulgatus ATCC 8482, Bordetella bronchiseptica ATCC 10580, Bordetella parapertussis ATCC 15237, Burkholduria cepacia ATCC 17765, Campylobacter jejuni ATCC 33291, Candida albicans ATCC 14053, Candida krusei (laboratory isolate), Candida tropicalis (laboratory isolate), Citrobacter freundii ATCC 8090, Corynebacterium diptheriae ATCC 13812, Enterobacter aerogenes ATCC 13048, Enterobacter cloacae (laboratory isolate), Enterococcus durans ATCC 6506, Enterococcus faecalis ATCC 29212, Enterococcus faecium ATCC 35667, Erysipelothrix rhusiopathiae ATCC 19414, Esherichia coli ATCC 35218, Flavobacterium indologenes (laboratory isolate), Flavobacterium mutltivoram ATCC 35656, Haemophilis influenzae ATCC 10211, Klebsiella pneumoniae ATCC 13883, Listeria monocytogenes ATCC 7646, Micrococcus luteus ATCC 4988, Proteus mirabilus ATCC 7002, Proteus vulgaris ATCC 6380, Providencia stuartii ATCC 35031, Pseudomonas aeruginosa ATCC 27853, Pseudomonas vesicularis (laboratory isolate), Saccharomyces cerevisiae ATCC 2366, Salmonella typhimurium ATCC 14028, Serratia marcescens (laboratory isolate), Serratia oderifera ATCC 33077, Shigella flexneri (laboratory isolate). Shigella sonnei ATCC 25931, Staphylococcus simulans ATCC 27851, Staphylococcus aureus (laboratory isolate), Staphylococcus aureus ATCC 33591, Staphylococcus aureus NCTC 6751, Staphylococcus capitis ATCC 27840, Staphylococcus cohnii ATCC 29974, Staphylococcus epidermidis (laboratory isolate), Staphylococcus haemolyticus ATCC 29970, Staphylococcus hominus ATCC 27844, Staphylococcus intermedius ATCC 29663, Staphylococcus lugdenensis (laboratory isolate), Staphylococcus scuiri (laboratory isolate), Staphylococcus warneri ATCC 27836, Staphylococcus xylosus ATCC 29971, Stenotrophomonas maltophilia (laboratory isolate), Streptococcus agalactiae ATCC 12386, Streptococcus bovis ATCC 9809, Streptococcus equi ATCC 9528, Streptococcus equisimilis ATCC 35666, Streptococcus (group B) ATCC 12386, Streptococcus (group F) ATCC 12392, Streptococcus (group G) ATCC 12394, Streptococcus mutans ATCC 35668, Streptococcus pneumoniae ATCC 27336, Streptococcus pyogenes ATCC19615, Streptococcus salivarius ATCC13419, Vibrio alginolyticus ATCC17749, Vibrio parahaemolyticus ATCC17802, Yarrowia lipolytica ATCC 9773 and Yersinia enterocolitica ATCC 23715. Genomic DNA was purified from cultures of these organisms and tested in the NGpapLC assay using the conditions described above. Results A total of 282 clinical samples were tested by the NGpapLC assay and by a testing algorithm combining the Roche Cobas Amplicor assay wife the cppB-LC assay. A summary of these results is provided in Table 2. Overall 79 (28.0%) specimens were positive and 120 (42.6%) specimens were negative for N. gonorrhoeae DNA by all three PCR methods. An additional 81 (28.7%) specimens were positive by the Cobas Amplicor assay but negative by both the NGpapLC and cppB-LC assays. These were considered to be false-positive results obtained by the Cobas Amplicor. A further two (0.7%) specimens were positive by the Cobas Amplicor assay but gave discrepant results on the LightCycler assays; one specimen was positive by the cppB-LC assay with a cycle threshold value (Ct value) of 47 but negative by NGpapLC whereas the remaining specimen was positive by NGpapLC only, providing a Ct value of 41. These Ct values were the highest recorded Ct values for each test and are indicative of low N. gonorrhoeae DNA concentrations in each specimen. Upon repeat testing, neither specimen was consistently positive. This suggests that the concentration of DNA in both specimens was on the threshold of sensitivity of the respective test. By testing dilutions of N. gonorrhoeae culture, ranging from 5×10E+4 to 5×10E−2 cfu/ml, the limit of sensitivity of the NGpapLC was determined to be 5 cfu/ml of N. gonorrhoeae in the specimen. The detection limit of the cppB-LC was determined to be 5×10E−1 cfu/ml. This suggests the cppB-LC has a 10-fold better detection limit than the NGpapLC assay. To further determine the specificity of the NGpapLC assay, genomic DNA was purified and tested from cultures of a broad panel of organisms. These included Neisseria species as well as other common human pathogens and normal flora. All of the non-gonococcal species were negative when tested by the NGpapLC assay. In contrast, three N. meningitidis isolates tested positive by the cppB-LC assay. These three N. meningitidis isolates provided cycle threshold (Ct) values in the cppB-LC assay that were significantly greater than those provided by the positive N. gonorrhoeae isolates; the Ct values of the N. gonorrhoeae isolates were consistently lower than 16 whereas these three N. meningitidis isolates provided Ct values of 33 or greater. This suggests the cppB gene may be present at lower copy number in these N. meningitidis isolates. Of the 84 N. gonorrhoeae isolates tested, seven were negative by the cppB-LC assay. Six of these seven negative isolates were the N. gonorrhoeae isolates obtained from the Northern Territory and had previously tested negative by the cppB-LC assay. Therefore only one additional cppB negative isolate was identified in the Queensland isolates. In contrast, all 84 N. gonorrhoeae isolates provided positive results when tested by the NGpapLC assay. This shows that the NGpapLC oligonucleotide targets were present in all isolates. In addition, fluorescent melting curve analysis by the NGpapLC assay showed no variation between N. gonorrhoeae isolates or any of the positive clinical specimens; all NGpapLC positive reactions provided melting temperatures of 65° C. NGpapLC Compared to Bacterial Culture A comparison with bacterial culture was performed on the local Queensland population and comprised of 557 specimens taken from patients attending sexual health clinics. This population was considered ideal for testing the specificity of the NGpapLC assay given the low incidence of N. gonorrhoeae in this population. Compared to bacterial culture, the assay was 100% sensitive and 88.2% specific (Table 3). However, this specificity calculation is based on the assumption that the two additional PCR positives are false-positive results. In contrast, we believe that these additional positive results are true positive results. This is because the results of the NgpapLC were supported by a second PCR assay targeting a separate N. gonorrhoeae gene. In addition, previous studies have shown that PCR has better clinical sensitivity than bacterial culture. Therefore, additional PCR positives would not be unexpected. Overall, the above results suggest the new NGpapLC assay is highly suitable for routine detection N. gonorrhoeae in clinical samples. Tables 4-7 provide a breakdown of the Table 3 data into specimen types. For both the urethral and cervical specimens the NGpapLC assay was 100% specific. The results of the throat-swabs suggest the NGpapLC is also suitable for use on these specimen types, as does the more limited data on anal swabs. Discussion The problems associated with the specificity of the Cobas Amplicor N. gonorrhoeae assay and the requirements for a confirmatory assay are well documented. Unfortunately, the conventional gene targets used for confirmatory tests have also proved to have limitations. The results of this study suggest the NGpapLC assay is a suitable alternative to the cppB-LC for confirmation of Cobas Amplicor N. gonorrhoeae positive results. By targeting the N. gonorrhoeae porA pseudogene, the NGpapLC overcomes the limitations associated with the cppB gene and provides the potential for improved clinical sensitivity and specificity. By testing dilutions of an ATCC strain of N. gonorrhoeae, the cppB-LC assay had a 10-fold better detection limit compared to our new NGpapLC assay. This presumably is because the cryptic plasmid is at a higher copy number than the N. gonorrhoeae porA pseudogene. Nevertheless, the difference in detection limits did not affect the clinical sensitivities of the assays. For the clinical specimens, the NGpapLC and cppB-LC assays gave good agreement for the detection of N. gonorrhoeae. Only two of the 282 specimens provided discrepant results, with each LightCycler assay detecting an additional positive over the other. Originally, it was considered that the additional cppB-LC positive result may have stemmed from the N. gonorrhoeae DNA load being below the detection limit of the NGpapLC assay. However, by using a more sensitive nested PCR assay we were still unable to detect the presence of the N. gonorrhoeae porA pseudogene in this specimen (data not shown). This suggests that this specimen was either a false-positive using our Roche Amplicor and cppB-LC testing algorithm or represents a N. gonorrhoeae strain lacking the porA pseudogene. Although, to date there have been no reports of N. gonorrhoeae strains lacking the porA pseudogene. It is further interesting to note that by using nested amplification we were able to detect the presence of the cppB gene in the specimen that was negative by the cppB-LC assay but positive by the NGpapLC test. Tins demonstrates that this cppB-LC negative result-did not occur because of the absence of the cppB gene in this presumptive N. gonorrhoeae strain (data not shown). Overall, the results for the clinical specimens suggest the NGpapLC and cppB-LC assays have similar clinical sensitivities and specificities and that the cppB-LC assay may in fact be suitable for use on urine and genital swab specimens in our population. However, these results are in contrast with those of the bacterial panel, which highlighted the limitations of the cppB-LC assay. Most notably the cppB-LC assay failed to detect seven N. gonorrhoeae isolates. This shows that in our population there are N. gonorrhoeae strains lacking the cppB gene. More importantly, our testing algorithm is likely to produce false-negative results; specimens testing positive by the Cobas Amplicor could incorrectly be identified as false-positives by the cppB-LC assay. In this study, N. gonorrhoeae isolates were not randomly selected, therefore more testing is required to determine the overall cppB-LC false-negative rate. Other studies have suggested that the incidence of such isolates lacking the cppB gene is low in Australia (Leslie et al., 2003, Commun Dis Intell. 27 373-9). Nevertheless, when using the cppB-LC assay the potential for false-negative results exists. In contrast, the NGpapLC method correctly identified all N. gonorrhoeae isolates tested in this study. This suggests the NGpapLC assay may not be susceptible to false-negative results arising from the absence of the porA pseudogene in our local N. gonorrhoeae strains. Hence, it should provide improved clinical sensitivity compared to the cppB-LC assay. The NGpapLC assay also proved to be highly specific for N. gonorrhoeae DNA; all non-gonococcal species provided negative results when tested by the NGpapLC method. It should be noted mat we experienced difficulty obtaining Neisseria species and so our bacterial panel did not include all known Neisseria species and only contained a limited number of isolates for most species. Therefore, cross-reactions with oilier Neisseria species cannot, be ruled out on the basis of these results alone. However, the Neisseria porA gene is only reported to exist in N. gonorrhoeae and N. meningitidis (Feavers & Maiden 1998, supra % and therefore cross-reactions with N. meningitidis were considered to be more relevant. In this study, we tested 38 N. meningitidis isolates and found no cross-reactions. As a result, we axe confident of the specificity of this test when used on our local sample population. The cppB-LC results for the bacterial panel provided a good example of the specificity problems associated with using the cppB target as positive results were obtained from three N. meningitidis cultures. Nevertheless, the presence of the cppB gene in local N. meningitidis isolates may not pose a major specificity problem if testing is restricted to urine and genital swab specimens. To date there have been no reports of N. meningitidis producing false-positive results in the Cobas Amplicor assay, and such isolates would be negative when initially screened by the Cobas Amplicor. On the other hand, the cppB gene has been found in isolates of other Neisseria species, including N. cinerea, which also cross-reacts with the Cobas Amplicor assay (Palmer et al., 2003, supra; Farrell, 1999, supra). Further, our study only examined a limited number of Neisseria species and strains, therefore, the possibility of cross-reactions wife other Neisseria species. In our population cannot be excluded. The importance surrounding the specificity of a confirmatory assay for N. gonorrhoeae is also dependent on specimen site. One of the key limitations of the Cobas Amplicor is that its specificity significantly declines when used on extra-genital sites. In particular, throat swabs are a major problem as they can possess various Neisseria species and so offer greater potential for false-positive cross-reactions. A recent study (Leslie et al., 2003, supra) found feat confirmation rates of Cobas Amplicor N. gonorrhoeae positive results dropped from 86.2% fox penile and urethral swabs to 5.6% for oropharyngeal swabs. It should be noted that even when using the cppB-LC confirmatory assay, the number of true positives obtained from throat swabs are likely to be much lower than those obtained from genital specimens. This is because the presence of multiple Neisseria species in throat swabs increases the chance of both assays providing false-positive results; one species could cross-react with the screening assay while another species may cross-react with the confirmatory assay, thus producing a false-positive result from the algorithm. We believe that the specificity provided by our new NGpapLC confirmatory assay may provide improved detection of N. gonorrhoeae in extra-genital sites. Our aim is to extensively evaluate the use of the NGpapLC assay on multiple specimen types, including throat swabs. The results of this study show the porA pseudogene is a suitable target for PCR detection of N. gonorrhoeae. It is worth highlighting that the porA gene was previously a popular target for the detection of N. meningitidis by PCR. However, it has since lost favour since it was discovered that insertion sequences may be incorporated into the porA gene of some N. meningitidis isolates giving false-negative results (van der Ende et al., 1999, Infect Immun. 67 2928-34; Newcombe et al., 1998, Mol Microbiol 30 453-4; Jelfs et al. 2000, Clin Diagn Lab. Immunol 7 390-5). Such mutations can potentially block PCR amplification or probe hybridization and hence prevent detection of some N. meningitidis isolates. The fact that all N. gonorrhoeae isolates were detected in tins study suggests that insertion sequences may not be found in the N. gonorrhoeae porA pseudogene. However, given that the selection of our N. gonorrhoeae isolates was not random, it is possible that N. gonorrhoeae isolates containing insertion sequences were simply missed by the study. Alternatively, insertion sequences may have been present but did not affect the NGpapLC assay because of its small PCR product size (132 bp); such a small PCR product size may reduce the probability of sequences inserting between the PCR primer targets. We aim to further evaluate the NGpapLC assay against an extended panel of N. gonorrhoeae isolates. Throughout the specification the aim has been to describe the preferred embodiments of the invention without limiting the invention to any one embodiment or specific collection of features. It will therefore be appreciated by those of skill, in the art that, in light, of the instant disclosure, various modifications and changes can be made in the particular embodiments exemplified without departing from the scope of the present invention. All patent and scientific literature, algorithms and computer programs referred to in this specification are incorporated herein be reference in their entirety. TABLE 1 NGpapLC primers and probes targeting the N. gonorrhoeae porA pseudogene Designation Sequence (5′ to 3′) Position papF: CGGTTTCCGTGCGTTACGA 681-699a papR: CTGGTTTCATCTGATTACTTTCCA 812-789a papP1: CATTCAATTTGTTCCGAGTCAAAACAGC-fluorescein 730-757a papP2: LCred640-AGTCCGCCTATACGCCTGCTACTTTCAC-Phosphate 759-786a aGenbank accession number AJ223448 TABLE 2 An improved confirmatory Neisseria gonorrhoeae real-time PCR assay targeting the porA pseudogene. Cobas Amplicor & Cobas Amplicor & cppB-LC testing cppB-LC testing N = 282 algoritm positive algoritm negative NGpapLC positive 79 1 NGpapLC negative 1 201* *81 of these specimens were positive by the Cobas Amplicor assay but negative by the cppB-LC assay. TABLE 3 All specimen types: PCR v Culture N = 557 Culture positive Culture negative NGpapLC positive 15 2* NGpapLC negative 0 540 *Currently, there is no assay available that could reliably be used for discrepant analysis on these specimens. However, these specimens were also positive by the cppB-LC (which can also cross-react with other Neisseria species). Further, these specimens provided comparable Ct values in both the NGpapLC and cppB-LC assays. This suggests that the bacterial DNA detected by these assays were at approximately the same concentration. Overall, these results suggest that these are true N. gonorrhoeae positive specimens. TABLE 4 Cervical swabs: PCR v Culture N = 218 Culture positive Culture negative NGpapLC positive 1 0 NGpapLC negative 0 215 TABLE 5 Urethral swabs: PCR v Culture N = 184 Culture positive Culture negative NGpapLC positive 9 0 NGpapLC negative 0 175 TABLE 6 Throat swabs: PCR v Culture N = 133 Culture positive Culture negative NGpapLC positive 1 1* NGpapLC negative 0 131 TABLE 7 Anal swabs: PCR v Culture N = 24 Culture positive Culture negative NGpapLC positive 4 1* NGpapLC negative 0 19

<SOH> BACKGROUND OF THE INVENTION <EOH>Neisseria gonorrhoeae , is a gram-negative diplococcal bacterial pathogen which is the causative organism of the sexually transmitted disease (STD) known as gonorrhoea. Although gonorrhoea is an ancient disease first described by Galen in AD 150, it is still a major STD of humans. Failure to detect and treat Neisseria gonorrhoeae infection can allow the disease to progress to a serious systemic infection that affects the heart, joints, meninges, eyes and pharynx. Thus, early definitive diagnosis can assist treatment of the disease and prevent the serious complications that can arise as a result of this bacterial infection. Although polymerase chain reaction (PCR) is the method of choice for routine detection of Neisseria gonorrhoeae , PCR has limitations and bacterial isolation has remained the gold standard for definitive diagnosis. This is largely because N. gonorrhoeae shares much sequence homology with other Neisseria species, including N. meningitidis , and in addition, contains many non-conserved sequences (Palmer et al., 2003, J. Clin. Microbiol. 41 835-7). Thus, there is a potential for both false-positive and false-negative results to occur when using PCR for routine detection of N. gonorrhoeae . In both situations the consequences may be significant. From a public health perspective, false-negative results may allow unchecked spread of the disease whereas false-positive results can have considerable social ramifications for patients. The Roche Cobas Amplicor system (Roche Diagnostics, Australia) is a PCR assay widely used for the detection of N. gonorrhoeae . Its appeal lies in its ability to simultaneously detect N. gonorrhoeae, Chlamydia trachomatis and the presence of inhibiting substances, while also carrying United States Food and Drug Administration (FDA) approval. However, the Cobas Amplicor system does have limitations. Most, notably, its N. gonorrhoeae assay is known to cross react with some strains of commensal Neisseria species, including N. subflava, N. cinerea, N. flavescens, N. lactamica and N. sicca (Palmer et al., 2003, supra; Farrell, 1999, J. Clin. Microbiol. 37 386-90). Consequently, there is a need to use a second PCR assay to confirm Cobas Amplicor positive results. In response, clinical laboratories have adopted in-house confirmatory assays. To date, the most common target for in-house confirmatory tests has been the cryptic plasmid (cppB) gene of N. gonorrhoeae , with several such protocols having been described (Ho et al., 1992, J. Clin Pathol. 45 439-442; Farrell, 19995 supra; Whiley et al., 2002, Diagn. Microbiol. Infect. Dis. 42 85-9; Tabrizi et al., 2004, Sex. Trans. Infect 80 68-71). In particular, a LightCycler based cppB PCR (cppB-LC) assay has been developed for conformation of Cobas N. gonorrhoeae positive specimens (Whiley et al., 2002, supra). However, serious concerns have now been raised over the sensitivity and specificity of N. gonorrhoeae assays targeting the cppB gene. Studies conducted in both the United Kingdom and Australia have identified N. gonorrhoeae isolates lacking the cppB gene (Palmer et al. 2003, supra, Ottawa; A cluster of culture-positive, but PCR false negative infections with Neisseria gonorrhoeae . Tapsall et al., Abstract 0129. 15th Biennial Congress of the International Society for Sexually Transmitted Diseases Research ISSTDR). Therefore, laboratories targeting this gene run the risk of false-negative results. In addition, the cppB gene could be present in commensal Neisseria strains, including N. cinerea , and so could also produce false-positive results (Palmer et al. 2003, supra). Cross-reaction is a significant problem for gonococcal nucleic acid-based diagnostic testing and horizontal genetic exchange in the Neisseria genus is the major source of these cross-reactions (Johnson et al., 2002, MMWR Recomm. Rep 18 1-38). Furthermore, gonococcal tests are used on non-sterile sites and other Neisseria strains may frequently be found in such sites. PCR detection of the porA gene has been used to detect. Neisseria meningitidis (Glustein et al., 1999, Molecular Diagnosis 4 233-9), partly due to an assumption that is gene is absent in commensal Neisseria (Feavers & Maiden, 1998, Mol. Microbiol. 30 647-656). Furthermore, in such assays, cross-reaction (or the potential for cross-reaction) is not a significant threat as these tests are used on sterile sites, including blood and CSF. The only other Neisseria species where a porA sequence has been identified is N. gonorrhoeae , which has a porA pseudogene of considerable sequence similarity to the N. meningitidis porA gene (Feavers & Maiden, 1998, supra). However, it is not clear whether this pseudogene is present in all strains of N. gonorrhoeae , nor has its absence in commensal strains been verified.

<SOH> SUMMARY OF THE INVENTION <EOH>Notwithstanding the fact that the N. gonorrhoeae porA pseudogene is an unlikely target for nucleic acid-based detection of N. gonorrhoeae and, more particularly for distinguishing between N. gonorrhoeae and N. meningitidis , and might not be present ubiquitously among N. gonorrhoeae isolates and strains or absent in commensal strains, the present inventors have developed a surprisingly sensitive and reproducible nucleic acid-based detection method using the N. gonorrhoeae porA pseudogene as a target. The present invention is therefore broadly directed to an method of determining whether an individual is or has been infected with Neisseria gonorrhoeae , which method utilizes a porA pseudogene or porA nucleic acid derived therefrom, as an indicator of infection. The present, invention is also broadly directed to one or more oligonucleotides which facilitate detection of a Neisseria gonorrhoeae , porA gene or porA nucleic acid. In a first aspect the invention provides a method of determining whether an individual is or has been infected with Neisseria gonorrhoeae , said method including the step of detecting an isolated porA nucleic acid of Neisseria gonorrhoeae , if present in a biological sample obtained from said individual, a presence of said porA nucleic acid indicating that said individual is or has been infected with Neisseria gonorrhoeae. Preferably, the method includes the step of subjecting a nucleic acid sample to nucleic acid sequence amplification under conditions which facilitate amplification of said isolated porA nucleic acid to a detectable level. In a second aspect the invention provides a method of determining whether an individual is or has been infected with Neisseria gonorrhoeae , said method including the step of selectively detecting or distinguishing an isolated porA nucleic acid of Neisseria gonorrhoeae , from a porA nucleic of another Neisseria species if present in said biological sample obtained from said individual, a presence of said isolated porA nucleic acid indicating mat said individual is or has been infected with Neisseria gonorrhoeae. Preferably, the method includes the step of subjecting a nucleic acid sample to nucleic acid sequence amplification under conditions which facilitate amplification of said isolated porA nucleic acid to a detectable level but which do not facilitate amplification of said porA nucleic of said another Neisseria species to a detectable level. Preferably, said another Neisseria species is N. meningitidis. In a preferred embodiment the invention provides a method of determining whether a human individual is or has been infected with Neisseria gonorrhoeae said method inducing the steps of: (i) subjecting a biological sample obtained from said human individual to nucleic acid sequence amplification to selectively produce a porA Neisseria gonorrhoeae , amplification product from a Neisseria gonorrhoeae , porA nucleic acid if present in said biological sample; and (ii) detecting said amplification product, if present, by probe hybridization whereby a presence of said porA amplification product indicates that said individual is or has been infected with Neisseria gonorrhoeae. In a third aspect, the invention provides an oligonucleotide which is capable of hybridizing to a porA nucleic acid of Neisseria gonorrhoeae , sufficiently to enable detection of said porA nucleic acid, but which is not capable of hybridizing to a porA nucleic acid of another Neisseria species sufficiently to enable detection of said porA nucleic acid of said another Neisseria species. Preferably, said another Neisseria species is N. meningitidis. In preferred embodiments, said oligonucleotide comprises a nucleotide sequence as set forth in Table 1 and FIG. 1 (SEQ ID NOS:3-9). In a fourth, aspect, the invention provides a kit comprising one or more oligonucleotides according to the third aspect together with a DMA polymerase and/or one or more detection reagents. In a fifth aspect the invention provides a nucleic acid array comprising an oligonucleotide according to the second aspect, immobilized, coupled, impregnated or otherwise in communication with a substrate. It will be appreciated that the invention provides a method and oligonucleotide mat facilitate detection of a porA nucleic acid of Neisseria gonorrhoeae. Preferably the porA nucleic acid corresponds to a fragment of a porA pseudogene of Neisseria gonorrhoeae. More preferably, according to tins embodiment the porA nucleic acid corresponds to a fragment of a porA pseudogene of Neisseria gonorrhoeae , which fragment has a nucleotide sequence distinct from a fragment of a porA gene or pseudogene of another Neisseria species. In a particularly preferred embodiment, the porA nucleic acid of Neisseria gonorrhoeae , comprises a nucleotide sequence to which an oligonucleotide is capable of annealing sufficient to enable detection of said porA nucleic acid. Suitably, said nucleotide sequence is not present in, or has one or more nucleotides different to, a nucleotide sequence of a porA nucleic acid of another Neisseria species, such that said oligonucleotide is not capable of hybridizing to said porA nucleic acid of said another Neisseria species sufficient to facilitate detection of said porA nucleic acid of said another Neisseria species. Preferably, said another Neisseria species is N. meningitidis. In a particularly advantageous embodiment, the method and oligonucleotide of the invention facilitate detection of a porA nucleic acid feat may be present in each, of a plurality of isolates, strains, allelic variants or sub-species of Neisseria gonorrhoeae. Throughout tins specification, unless otherwise indicated, “comprise”, “comprises” and “comprising” are used inclusively rather than exclusively, so that a stated integer or group of integers may include one or more other non-stated integers or groups of integers.

20061030

20110816

20090521

97158.0

C12Q168

ZEMAN, ROBERT A

NEISSERIA GONORRHOEAE DETECTION

UNDISCOUNTED

ACCEPTED

C12Q

ACCEPTED

Hydrogen Generation Apparatus Incorporating a Staged Catalyst and Method for Using Same

A method and apparatus for generation of hydrogen. The apparatus includes a hydrogen reactor chamber (99) and a plurality of catalysts within the chamber (99) forming distinct zones or portions (200, 202, and 204), each zone or portion comprising a distinct catalyst or combination thereof. Said plurality of catalysts include at least one of a high-activity steam reformation catalyst, coke resistant steam reformation catalyst and steam reformation catalyst that promotes a water gas shift reaction.

1. A method for generating hydrogen, comprising: providing a hydrogen reactor chamber; providing a plurality of catalysts within said hydrogen reactor chamber to form a staged catalyst medium, the staged catalyst medium comprising a series of distinct zones or portions, each zone or portion comprising a distinct catalyst or combination thereof having a unique definitive characteristics; and passing a feed stream of hydrocarbons through the staged catalyst medium to produce hydrogen. 2. The method of claim 1, wherein said plurality of catalysts is comprised of at least one of a high-activity steam reformation catalyst and a coke-resistant steam reformation catalyst. 3. The method of claim 2, wherein said plurality of catalysts is further comprised of a steam reformation catalyst that promotes a water-gas shift reaction. 4. The method of claim 1, further comprising introducing said feed stream of hydrocarbons into said hydrogen reactor chamber. 5. The method of claim 1, wherein said feed stream of hydrocarbons is a fuel having at least one of a C1-C4 hydrocarbon or mixture, or a C1-C4 oxygenate thereof. 6. The method of claim 1, wherein at least 300 sccm of hydrogen or reformed gas stream is produced in conjunction with residence times of less than about 0.5 sec. 7. The method of claim 4, wherein said at least one hydrocarbon is propane and provides hydrogen production at residence times of about 0.15 to about 0.30 sec and at a temperature of about 575° C. 8. The method of claim 1, wherein providing a plurality of catalysts within the reactor chamber can be performed by loading said plurality of catalysts within said hydrogen reactor chamber such that said feed stream of hydrocarbons is exposed to said plurality of catalysts in a predetermined sequential manner. 9. The method of claim 8, further comprising introducing said feed stream of hydrocarbons to a steam reformation catalyst, the reformation catalysts also promoting the water-gas shift reaction, the reformation catalyst located adjacent entrance or exit portions of said hydrogen reactor chamber. 10. The method of claim 1, wherein providing a plurality of catalysts within the reactor chamber can be performed by loading said plurality of catalysts within said hydrogen reactor chamber such that said staged catalyst medium includes a first portion having a steam reformation catalyst, which also promotes the water-gas shift reaction, located adjacent entrance or exit portions and a second portion including at least one of a high-activity steam reformation catalyst and a coke-resistant steam reformation catalyst. 11. The method of claim 2, wherein providing a plurality of catalysts within the reactor chamber can be performed such that the high reforming and water gas shift activity characteristics of at least one catalyst is balanced with resistance to coking. 12. The method of claim 11 wherein said coke-resistant catalyst is loaded at an entrance of the hydrogen reactor chamber, followed by said high-activity catalyst or wherein all or part of the coke-resistant catalyst is mixed with said high-activity catalyst, before loading into the hydrogen reactor chamber. 13. The method of claim 1, further comprising the step of hot swapping of fuels in the C1-C4 range to obtain fuel flexibility and uninterrupted production of hydrogen or a reformed gas stream. 14. A hydrogen generation apparatus comprising a reactor chamber wherein a hydrogen generating reaction is performed, the reactor chamber comprising a plurality of catalysts in a staged configuration, wherein the plurality of staged catalysts is provided to form a staged catalyst medium. 15. A hydrogen generating apparatus wherein hydrogen is generated by steam reformation of a hydrocarbon fuel, the apparatus comprising a steam reformer wherein a reaction resulting in steam reformation of the hydrocarbon fuel is performed, the steam reformer including a portion having a plurality of steam reformation catalysts disposed therein. 16. The hydrogen generating apparatus of claim 15, wherein said plurality of steam reformation catalysts are provided in a staged configuration. 17. The hydrogen generating apparatus of claim 16, wherein said staged configuration includes a coke-resistant steam reformation catalyst loaded at an entrance of said steam reformer. 18. The hydrogen generating apparatus of claim 15, wherein said plurality of steam reformation catalysts includes at least two of a high-activity steam reformation catalyst, a coke-resistant steam reformation catalyst and a steam reformation catalyst which promotes a water-gas shift reaction. 19. The hydrogen generating apparatus of claim 18, wherein said high-activity steam reformation catalyst is a supported nickel-based catalyst. 20. The hydrogen generating apparatus of claim 17 or 18 wherein said coke-resistant stream reformation catalyst is a supported doped nickel-based catalysts. 21. The hydrogen generating apparatus of claim 20, wherein said supported doped nickel-based catalyst is comprised of at least one of calcium oxide, potassium oxide and calcium aluminate or combinations thereof. 22. The hydrogen generating apparatus of claim 21, wherein said supported doped nickel-based catalysts is further comprised of at least one noble metal. 23. The hydrogen generating apparatus of claim 22, wherein said at least one noble metal is at least one of platinum, palladium, rhodium, or ruthenium or any combination thereof. 24. The hydrogen generating apparatus of claim 18, wherein said coke-resistant stream reformation catalyst is loaded at an entrance of said steam reformer, followed by said high-activity steam reformation catalyst. 25. The hydrogen generating apparatus of claim 19, wherein the high activity steam reformation catalyst contains at least one noble metal component. 26. The hydrogen generating apparatus of claim 15, wherein the plurality of catalysts are powders or coatings supported on a substrate. 27. The hydrogen generating apparatus of claim 26, wherein said substrate is selected from the group consisting of foams, monoliths, felts and mesh, or any combination thereof. 28. The hydrogen generation apparatus of claim 15, wherein a fuel cell is in fluid communication with the hydrogen generation reactor. 29. A method for generating hydrogen by steam reformation of a hydrocarbon fuel, the method comprising: providing a steam reformer; providing a plurality of catalysts within the steam reformer to form a staged catalyst medium; and passing a hydrocarbon fuel feed stream in the steam reformer to obtain a hydrogen containing reformed stream, the reformed stream is purified to produce hydrogen. 30. A method for manufacturing a hydrogen generation apparatus, the method comprising: providing an element of the apparatus wherein a reaction associated with hydrogen production is performed; and providing within said element a plurality of catalysts in a staged catalyst medium, the staged catalyst medium comprising a series of distinct zones or portions, each zone or portion comprising a distinct catalyst or combination thereof. 31. The method of claim 29, wherein purification of the reformer stream is achieved using a hydrogen separation membrane.

RELATED APPLICATIONS This application claims priority of U.S. Provisional Application No. 60/561,750 filed on Apr. 12, 2004, and of PCT application No. PCT/US04/37620 filed on Nov. 11, 2004, all herein incorporated by reference in their entirety. FIELD OF THE INVENTION The present invention generally relates to the chemical arts. More particularly, the present invention relates to an apparatus and method for generating hydrogen gas by the steam reformation of hydrocarbons. BACKGROUND OF THE INVENTION The growing popularity of electronic devices has produced an increased demand for electrical power sources to energize these devices. At present, storage or rechargeable batteries are typically used to provide independent electrical power sources for electronic devices. However, the amount of energy that can be stored in storage or rechargeable batteries is insufficient to meet the need of certain applications. Fuel cells, including hydrogen/air fuel. cells (H/AFCs) have enormous potential as a replacement for batteries. Fuel cells can operate on very energy-dense fuels. Some fuel cell-based power supplies offer high energy-to-weight ratios compared with even state-of-the-art batteries. Functionally, fuel cells generate electricity by reacting hydrogen with oxygen to produce water. For example, in a PEM H/AFC hydrogen atoms pass through a membrane as H+ while the electrons travel around the membrane, the H+s join with oxygen, on the otherside of the membrane to form water. Since oxygen can typically be obtained from the ambient atmosphere, only a source of hydrogen must be provided to operate a fuel cell. Merely providing compressed hydrogen is not always a viable option, because of the substantial volume that even a highly compressed gas occupies. Liquid hydrogen, which occupies less volume, is a cryogenic liquid, and a significant amount of energy is required to maintain the extremely low temperatures required to maintain it as a liquid. Furthermore, there are safety issues involved with the handling and storage of hydrogen in the compressed gas form or in the liquid form. Among the most desirable alternative hydrogen sources is hydrogen produced by the steam reformation of hydrocarbons, particularly C1-C4 hydrocarbons. For example, C1, methane, as natural gas, and C3, propane, are used for residential, mobile home and recreational services, while propane and C4, butane, are used as fuels for backpack stoves. Following are the reaction equations for the steam reforming method, where methane is the feedstock: CH4+H2O→CO+3H2 Equation (1) CH4+2H2O→CO2+4H2 Equation (2) It is a drawback of the reformation of such hydrocarbon fuels, that coke, a solid residue which reduces the activity and lifetime of the steam reformation and catalyst and is undesirable in a fuel cell application, is formed. Consequently, there is a desideratum for an apparatus and method that has the flexibility to effectively and efficiently generate hydrogen from C1-C4 hydrocarbon fuels without necessitating a change in the catalyst, while minimizing the production of coke residue. SUMMARY OF THE INVENTION Now in accordance with this invention there has been found a hydrogen generation apparatus for use with fuel cells and other applications wherein generation of hydrogen is required or desirable. According to a first aspect a method for generating hydrogen is disclosed, the method comprising providing a reactor chamber; providing a plurality of catalysts within the reactor chamber to form a staged catalyst medium; and passing a fuel feed stream, such as a hydrocarbon fuel stream, in the reactor chamber to produce hydrogen or a hydrogen containing product gas. Providing a plurality of catalysts within the reactor chamber can be performed by packing or loading the plurality of catalysts in the staged catalyst medium within the chamber. A staged catalyst medium is a medium comprising a series of distinct zones or portions, each zone or portion comprising a distinct catalyst or combination thereof having a unique definitive characteristic. A definitive characteristics, is a characteristic of the catalyst or combination thereof identifying a physical and/or chemical property of the catalyst or combination thereof which is associated with the hydrogen generation as performed in the apparatus. Zones boundaries may vary. Zone boundaries may be characterized by an abrupt end to the catalysts, may be characterized by a decreasing or increasing gradient of one or more catalysts or catalytic activity, or may be characterized by any combination thereof. Each zone or portion comprises a catalyst or combination thereof such that the definitive characteristic of the catalyst or combination thereof is unique, i.e. not presented by catalysts or combination thereof comprised in other zones or portions of the staged catalyst medium. A definitive characteristic of the catalyst in each zone or portion and the location of the zones or portions in the staged catalyst medium is a function of a desired effect to be performed in the zone or portion, the effect associated with the hydrogen generation performed in the reactor, the structure and/or the operation mode of the reactor. In some exemplary implementations, the plurality of catalysts are packed or loaded in the staged catalyst medium within the reactor chamber such that the feed stream passed in the reactor chamber is exposed to the plurality of catalysts in a predetermined sequential manner. The predetermined sequential manner can be determined in view of several factors associated with the desired production of hydrogen, such as the selected hydrogen generating reaction to be performed in the reactor, presence and location of pre-reformation zones in the reactor, selection of operating mode of the reactor. Accordingly, in exemplary implementations wherein the hydrogen generation is performed by steam reformation, providing a plurality of catalysts within the reactor chamber in a staged catalyst medium can be performed such that a steam reformation catalyst is located in the staged catalyst medium in a zone adjacent the entrance portion and/or typically exit portion of the hydrogen reactor chamber, the catalysts promoting a water-gas shift reaction. Also, in exemplary implementations, wherein a pre-reformation zone is included in the chamber, providing a plurality of catalysts within the reactor chamber in a staged catalysts medium can be performed such that a steam reformation catalysts is located in the staged catalyst medium in a zone located in the prereformation zone. In exemplary implementations, wherein a hydrogen separation membrane is included in the reactor, providing a plurality of catalysts within the reactor chamber can be performed such that hydrogen that is contained in the product gas can be separated through a palladium based membrane that is located either internal or external to the reactor. Additionally, providing a plurality of catalysts within the reactor chamber in a staged catalyst medium can be performed such that a predetermined catalyst is packed or loaded in the staged catalyst medium in a zone located in a portion of the reactor wherein the temperature is adjusted to enhance the performance of the catalysts in the reactor. Providing a plurality of catalysts within the reactor chamber in a staged catalyst medium can also be performed such that staged catalyst medium includes a first portion having at least one of a high-activity steam reformation catalyst and a coke-resistant steam reformation catalyst and a second portion having a steam reformation catalyst that promotes a water-gas shift reaction, located adjacent exit portion of the hydrogen reactor chamber. Providing a plurality of catalysts within the reactor chamber in a staged catalyst medium can be performed so that the staged catalyst medium comprises a plurality of catalysts provided and comprised of at least one of a high-activity steam reformation catalyst and a coke-resistant steam reformation catalyst. In some exemplary implementations the plurality of catalysts is further comprised of a steam reformation catalyst that promotes a water-gas shift reaction. Providing a plurality of catalysts within the reactor chamber in a staged catalyst medium can be performed so that the coke-resistant steam reformation catalyst is loaded at an entrance of the hydrogen reactor chamber, followed by a high-activity steam reformation catalyst. Alternatively, all or part of the coke-resistant steam reformation catalyst can be mixed with the high-activity steam reformation catalyst before loading into the hydrogen reactor chamber. Providing a plurality of catalysts within the hydrogen generating apparatus in a staged catalyst medium and/or passing a feed stream in the reactor chamber can also be performed such that the high reforming and water gas shift activity features of at least one catalyst is balanced with resistance to coking. The method can also comprise adjusting the operating parameters of the hydrogen generating apparatus to enhance the performance of the plurality of catalyst in the staged catalyst medium. In particular, the temperature of the reactor can be adjusted so that the zone including a determined catalyst is brought at the desired operating temperature of the catalysts for example by employing heat exchange. According to a second aspect a hydrogen generation apparatus is disclosed, the apparatus comprising a reactor chamber, the reactor chamber comprising a plurality of catalysts in a staged configuration, wherein the plurality of staged catalysts is provided in a staged catalyst medium. In particular, the plurality of catalysts can be located in the reaction chamber in any of the staged catalyst medium herein described. The staged catalyst medium can also be located in other portions of the hydrogen generating apparatus, such as pre-reformer, wherein hydrogen producing reactions and/or additional reactions associated with hydrogen production in the apparatus are performed. According to a third aspect, a hydrogen generating apparatus wherein hydrogen is generated by steam reformation of a hydrocarbon fuel is disclosed. The apparatus comprises a steam reformer wherein a reaction resulting in steam reformation of a hydrocarbon fuel is performed, the steam reformer including a portion having a plurality of steam reformation catalysts disposed therein. The plurality of steam reformation catalysts can be provided in a staged configuration, wherein the plurality of catalysts are included in a staged catalyst medium. In particular, the plurality of catalysts can be located in the steam reformer in any of the staged catalyst medium herein described. The staged configuration can in particular include a staged catalyst medium including a coke-resistant steam reformation catalyst loaded at an entrance of the steam reformer. Furthermore, the plurality of steam reformation catalysts in the staged catalyst medium can include at least two of a high-activity steam reformation catalyst, a coke-resistant steam reformation catalyst and a steam reformation catalyst which promotes a water-gas shift reaction. The high-activity steam reformation catalyst can be a supported nickel-based catalyst and the coke-resistant steam reformation catalyst can be a supported doped nickel-based catalysts. In an embodiment, the supported doped nickel-based catalyst can be comprised of at least one of calcium oxide, potassium oxide and calcium aluminate or combinations thereof. In some exemplary implementations the supported doped nickel-based catalysts is further comprised of at least one noble metal, such as at least one of platinum, palladium, and rhodium or combination thereof. The coke-resistant stream reformation catalyst can be loaded at an entrance of the steam reformer, followed by the high-activity steam reformation catalyst. According to a fourth aspect, a method for generating hydrogen by steam reformation of a hydrocarbon fuel is disclosed. The method comprises providing a steam reformer; providing a plurality of catalysts within the steam reformer in a staged catalyst medium; passing a hydrocarbon fuel. feed stream in the steam reformer to obtain a hydrogen containing reformed stream, the reformed stream purified to produce hydrogen. Providing a plurality of catalysts in the steam reformer to. form a staged catalysts medium can include locating the plurality of catalysts to form a staged catalyst medium in the steam reformer in any of the staged catalyst medium herein described wherein the chemical and/or physical activity associated with hydrogen production is also associated to steam reformation reactions. Purification of the hydrogen can be achieved by hydrogen separation membranes that are situated either internal or external to the steam reformer. The feed stream of hydrocarbons can be a fuel having at least one of a C1-C4 hydrocarbon or mixture or oxygenate thereof. Catalysts may be provided on a number of useful carriers, such as foams, monoliths, felts, pellets or powders, or any combination thereof. According to a fifth aspect, a method for manufacturing a hydrogen generation apparatus is disclosed, the method comprises providing an element or component of the hydrogen generation apparatus wherein a reaction associated with hydrogen production is performed, such as a reaction chamber; and providing within said element a plurality of catalysts to form a staged catalyst medium, the staged catalyst medium comprising a series of distinct zones or portions, each zone or portion comprising a distinct catalyst or combination thereof. The reaction chamber is preferably a steam reformer. The hydrogen generation apparatuses herein disclosed can also comprise a other elements or components identifiable by a person skilled in the art, such as fuel supply, a water supply, an oxygen supply, an air intake, and a vaporizer. Each of the elements included in the hydrogen generation apparatus according to the disclosure are connected to other elements by related lines identifiable by a person skilled in the art. According to the teachings of the present invention, exemplary methods and apparatuses can provide for at least 300 sccm of a reformed stream containing about 60% hydrogen produced in conjunction with residence times of less than about 0.5 sec, preferably less than about 0.4 sec. In a particular embodiment, the at least one C1-C4 hydrocarbon is propane and provides hydrogen production at residence times of about 0.15 to about 0.30 sec, preferably from about 0.20 to about 0.28 sec at about 575° C . Such a reformed gas stream containing hydrogen, when routed to a fuel cell such as a solid oxide fuel cell (SOFC), is capable of generating about 15 to 25 W of power based on the characteristics of the SOFC. The features believed to be novel are set forth within. However, the features both as to configuration, and method of operation, and the advantages thereof, may be best understood by reference to the following descriptions taken in conjunction with the diagrams, figures and accompanying drawings. BRIEF DESCRIPTION OF THE FIGURES The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying figures, wherein: FIG. 1 shows a block diagram illustrating the primary components of a hydrogen generator in accordance with the present invention; FIG. 2 shows an exemplary hydrogen reactor chamber packed/loaded in accordance with the teachings of the present invention; FIG. 3 shows an exemplary hydrogen generating reactor depicting the bottom portion and an exemplary channeled insert made in accordance with the teachings of the present invention; FIG. 4 shows an exemplary hydrogen generating reactor having the exemplary channeled insert in place; FIG. 5 shows an embodiment of an assembled (covered) exemplary hydrogen generating reactor; FIG. 6 shows a diagram illustrating an exemplary methane conversion and hydrogen concentration in function of the temperature during steam reformation in an exemplary hydrogen generation reactor; on the y axes the methane conversion percentage and the hydrogen mole percentages are reported; on the x axis the temperature is reported; FIG. 7 shows a diagram illustrating exemplary hydrogen production rates during steam reformation of methane in an exemplary hydrogen generation reactor; on the y axes the hydrogen flow in standard centimeter cube per minute are reported; on the x axis the temperature is reported. FIG. 8 shows a diagram illustrating exemplary hydrogen (H2—black squares), carbon dioxide (CO2—white squares) and methane (CH4 white circles) concentrations in an exemplary hydrogen generation reactor; on the y axis the concentration as mol % is reported; on the x axis the time is reported; FIG. 9 shows a diagram illustrating exemplary carbon monoxide concentrations in the dry product gas during steam reformation of methane in an exemplary hydrogen generation reactor; on the y axis the concentration as mol % is reported; on the x axis the time is reported; FIG. 10 shows a diagram illustrating a comparison equilibrium methane conversion vs. experimental values, in an exemplary hydrogen generation reactor; on the y axis the methane conversion concentration as mol % is reported; on the x axis the temperature is reported; FIG. 11 shows a diagram illustrating an equilibrium hydrogen concentrations vs. experimental values in an exemplary hydrogen generation reactor; on the y axis the concentration as mol % is reported; on the x axis the temperature is reported; FIG. 12A shows a diagram illustrating production of H2, CO2 and propane in an exemplary hydrogen generation reactor, during a “hot swap” of fuels; on the y axis the concentration as mol % is reported; on the x axis the time is reported; FIG. 12B shows a diagram illustrating production of CO, CH4 and C2 in an exemplary hydrogen generation reactor, during a “hot swap” of fuels; on the y axis the concentration as mol % is reported; on the x axis the time is reported; FIG. 13A shows a diagram illustrating production H2, CO2 and C4 (butane) in an exemplary hydrogen generation reactor, during a “hot swap” of fuels; on the y axis the concentration as mol % is reported; on the x axis the time is reported; FIG. 13B shows a diagram illustrating production CO, CH4 and C2 and C3 in an exemplary hydrogen generation reactor, during a “hot swap” of fuels; on the y axis the concentration as mol % is reported; on the x axis the time is reported; FIG. 14 is a schematic diagram of an exemplary apparatus for vaporizing butane prior to feeding butane into an exemplary hydrogen generator of FIG. 5. FIG. 15A shows a diagram illustrating production of H2, CO2 and C3 and C4 (butane) in an exemplary hydrogen generation reactor, during a “hot swap” of fuels; on the y axis the concentration as mol % is reported; on the x axis the time is reported; FIG. 15B shows a diagram illustrating production of CO, CH4 and C2 in an exemplary hydrogen generation reactor, during a “hot swap” of fuels; on the y axis the concentration as mol % is reported; on the x axis the time is reported; FIG. 16A shows a diagram illustrating production of H2, CO2 and C3 in an exemplary hydrogen generation reactor, during a “hot swap” of fuels; on the y axis the concentration as mol % is reported; on the x axis the time is reported; and FIG. 16B shows a diagram illustrating production of CO, CH4 and C2 in an exemplary hydrogen generation reactor, during a “hot swap” of fuels; on the y axis the concentration as mol % is reported; on the x axis the time is reported. DETAILED DESCRIPTION OF THE PREFERRED EXEMPLARY IMPLEMENTATIONS Particular exemplary implementations of the invention are described below in greater detail for the purpose for illustrating its principles and operation. However, various modifications may be made, and the scope of the invention is not limited to the exemplary exemplary implementations or operation described. For example, while specific reference is made to a reactor containing a channeled insert, it can be appreciated that any reactor suitable for the steam reformation of C1-C4 hydrocarbons can be advantageously employed. It is advantageous that the hydrogen generators provided, with only minor modifications, can be used to generate hydrogen from C1-C4 hydrocarbons and combinations thereof, without changing catalysts thereby facilitating multi-fuel reforming. In some exemplary implementations the hydrocarbon feed can be switched from one to another while the reactor is under operation facilitating hot-swapping of fuels. For example, the. hydrogen generator is useful with a combination 60% butane and 40% propane available commercially available as Powermax fuel, from Coleman Company (Wichita, Kans.). Such hydrocarbons are conventionally stored and transported as liquefiable gases. FIG. 1 shows an exemplary hydrogen generator 10. This. hydrogen generator can be supplied with one or more C1-C4 hydrocarbon fuels and water to generate hydrogen gas. The hydrogen generator includes a fuel supply 12, a water supply 14, and an oxygen supply 16, e.g., an ambient air intake, a vaporizer 18, a preheater 20, and a steam reformer 22. The hydrogen generator preferably includes a water storage tank (not shown), a fuel pressurizer 24 (if needed), and a water pump 26. Appropriate fluid conduits or lines are included as shown, and arrowheads incorporated into such fluid conduits indicate the proper flow of fluid through the hydrogen generator. A water supply conduit 40 and an air supply conduit 42 provide a fluid connection between the water supply 14 and the vaporizer 18 and the air supply 16 and the vaporizer, respectively. A fuel supply conduit 44 provides a fluid connection between the fuel supply 12 and a mixing tee 45. The embodiment shown in FIG. 1 includes a first pair of sulfur adsorption beds 70a and 70b located in the fuel supply conduit 44, between the fuel supply 12 and the mixing tee 45. While adsorption bed 70a is online, removing sulfur from the natural gas or some other C1-C4 hydrocarbon feed, adsorption bed 70b is regenerated and vice versa. Suitable sulfur adsorbents include activated carbon, molecular sieves and zinc oxide. A preferred sulfur adsorbent is regenerable activated carbon containing a transition metal such as copper and/or iron. Such regenerable catalysts as are available from Nucon International (Columbus, Ohio). The vaporizer 18 has an oxygen inlet 46, a water inlet 48, and a steam outlet 50. Since vaporization is endothermic, the vaporizer also includes a combustor to supply the heat necessary for vaporization by combustion of the fuel. The combustion product gases, i.e., carbon dioxide and water, exit the vaporizer through a combustion products outlet 52 into a combustion products line 54. The hydrogen generator 10 can include an additional stream splitter 60 located in the fuel supply conduit 44. The splitter directs a predetermined amount of the fuel to the combustor integrated with the vaporizer 18, to the combustor integrated with the preheater 20 and to the combustor integrated with the steam reformer 22. Fuel, and steam leaving the vaporizer 18, are combined in the mixing tee 45 and then directed through a feed gas line 56 to a preheater feed gas inlet 58. In a preferred embodiment the steam is present in an amount in excess to the stoichiometric value, that is, typically between 1 and 2. In preferred embodiments, the actual steam to carbon ratio is between 2 and 3. In one exemplary implementation, the preheater is a section of tubing packed with an inert particulate material. Suitable particulate materials include quartz, white sand, and alumina, with quartz being most preferred. In one preferred embodiment, the preheater 20 is made of a section of stainless steel tubing. The tubing is packed with quartz particles to yield a ratio of tubing length to equivalent particle diameter (L/dp) of from about 50:1 to about 100:1 preferably about 150:1 and a ratio of tubing internal diameter to equivalent particle diameter (D/dp) of from about 5:1 to about 10:1, preferably about 9:1. The mixture is heated to within 50° C. of the desired reaction temperature, e.g., to from about 525° C. to about 575° C., before it is directed out of a preheated feed gas outlet into a preheated feed gas line 62. The hot combustion product gases, i.e., carbon dioxide and water, exiting the vaporizer through a combustion products outlet 52 into a combustion products line 54, is routed to the pre-heater 20 to supply heat required for pre-heating. In one embodiment, the pre-heater section can be a portion of the reactor chamber itself. The steam reformer 22 has a preheated feed gas inlet 64, in fluid connection with the preheated gas line 62, and a reformed gas outlet 66. Since reformation is endothermic, the steam reformer 22 also includes a combustor to supply the heat necessary for reformation by combustion of the fuel. In one exemplary implementation, the steam reformer 22 is a hydrogen membrane reactor as described in PCT/US02/12822, filed Apr. 23, 2002, which application is herein incorporated by reference. In other exemplary implementations, the steam reformer can be a MesoChannel Reactor (see below) wherein the channels of the hydrogen membrane reactor preferably have a height and/or width between 0.01 mm and 10 mm, more preferably between 0.5 an 1.0 mm, and still more preferably between 0.4 and 0.5 mm. The aspect ratio (height/width) of the channels is generally greater than 2, preferably greater than 4, and more preferably greater than about 4.5. In some exemplary implementations the catalysts can be introduced by the coldspray technique described in PCT Application No. PCT/US04/3762 filed on Nov. 11, 2004, herein incorporated by reference in its entirety. The reformed gas stream exiting the steam reformer 22 is directed through reformed gas conduit 72 into a water condenser 74, where water is condensed and separated from the hydrogen gas. FIG. 2 is an exemplary hydrogen reactor chamber 99 containing catalysts loaded in accordance with one aspect of the present disclosure. The hydrogen reactor chamber 99 is also denominated “MesoChannel Reactor” and provides means by which different catalysts can be loaded and tested. In the MesoChannel Reactor 99, a block 100 is included in a housing 102 which consists of a top cover 104 and a bottom base 106, each containing a knife edge that could cut into a metal gasket, that is preferably nickel or copper, to provide a leak-tight seal. The top cover 104 and the bottom base 106 were assembled using socket head cap screws 105. The bottom base contained a tubing 108 for feeding reactants at one end and a tubing 110 for removing product gases on the opposite end. In the reactor of FIG. 2, tubing 108 are formed by an ⅛″ OD stainless steel tubing (SS 316 grade) and tubing 110 are formed be an ⅛″ OD stainless steel (SS 316 grade). The block 100 includes channels 101. Channels 101 as shown in FIG. 2 were machined into a metal block that was 76.2 mm length×37.6 mm width using CNC milling on both sides of a block 100. Preferable materials of construction are stainless steel 304, Inconel 600, and when it is required to decrease the component weight, titanium. Block 100 was then inserted into a housing 102 constructed preferably out of stainless steel (SS 304 grade) as exemplarily shown in FIGS. 3 and 4. While exemplary channels 101 do not have any curves, other configurations of channels 101 can also be provided, such as serpentine or curves, if so desired. An exemplary block 100 having channels 101 can be about 30 g in weight. Block 100 includes a staged catalyst medium wherein catalysts possessing unique distinctive characteristics are disposed in zones identified with numerals 200 202 and 204. Catalyst loading in zones 200 202 and 204 is accomplished utilizing a plurality of catalyst powders within the hydrogen reactor chamber, wherein each of the plurality of catalyst powders possesses unique definitive characteristics, packed in the reactor such as to provide a staged catalyst medium through which the feed stream of hydrocarbons is passed, to liberate hydrogen. Exemplary catalysts include high-activity catalysts, coke-resistant steam reformation catalysts and steam reformation catalysts that also promotes a water-gas shift reaction. In one example, although not limited thereto, zones are provided, here for example the three zones 200, 202 and 204, and are packed with the respective catalyst powders or blends thereof, as desired. The lines used in FIG. 2 to delineate zones 200, 202 and 204 are for demonstration/explanatory purposes and in no way are meant as a limitation of possible configurations/overall geometry of multi-catalyst packing, as described herein. Graded/transitional portions/zones, having mixtures/a blend of catalysts that comprise zones adjacent thereto, can also be provided, such that the fluid flow passes transitional portions disposed between a first provided zone and a second provided zone. For example, the fluid is first exposed to a first catalyst in a first zone, then passes a graded/transitional portion having a mixture of a first catalyst and a second catalyst, then passing through a second zone having the second catalyst. While three zones are exemplarily depicted in FIG. 2, any number of useful zones may be provided and loaded with catalysts, in accordance with concept of staged configuration disclosed herein. FIGS. 3 to 5 show an exemplary assembly process of the MesoChannel Reactor as shown in FIG. 2. FIG. 3 depicts exemplary reactor components of hydrogen reactor chamber 99 showing the housing 102, the block 100 containing channels 101, and top cover 104 prior to assembly. The assembly of these reactor components incorporation of catalysts yields an exemplary partially assembled “MesoChannel Reactor”. FIG. 4 depicts exemplary reactor components of hydrogen reactor chamber 99 with block 100 in place. Housing 102 was designed in such a manner so as to provide a leak-tight assembly when tested at pressures of up to 100 psig. The housing 102 consists of a top cover 104 and a bottom base 106, each containing a knife edge that could cut into a metal gasket, that is preferably nickel or copper, to provide a leak-tight seal. When changing catalysts is not required, the top cover 104, the bottom base 106 and the reactor can be sealed using conventional welding or brazing techniques. FIG. 5 depicts an exemplary assembled MesoChannel reactor. The top cover 104 and the bottom base 106 shown in FIG. 4 were assembled using socket head cap screws 105. The bottom base contained an ⅛″ OD stainless steel tubing 108 (SS 316 grade) for feeding reactants in at one end and an ⅛″ OD stainless steel tubing 110 (SS 316 grade) for removing product gases on the opposite end. In this embodiment, each end of the base also had provisions to accommodate 1/16″ OD thermocouples. In one embodiment, the volume of this exemplary reactor with a titanium insert in place was measured to be 10 cc. The MesoChannel Reactor is one of the hydrogen generating reaction chambers also suitable for steam reformation of hydrocarbon fuel. In some exemplary implementations, the MesoChannel Reactor can be included as a steam reformer 22 in a hydrogen generating apparatus such as hydrogen generating apparatus 10 depicted in FIG. 1. In other exemplary implementations, the steam reformer 22 is constituted by a hydrogen membrane reactor including a hydrogen separation membrane. Steam reforming of hydrocarbons in the C1-C4 range is described in the non-limiting examples below. In these examples, the reformer temperature was intentionally held below 625° C., and more preferably at about 575° C. Operating at these temperature offers the following advantage, namely, enhancing the stability of the hydrogen separation membrane when the hydrogen generator is operated as a membrane steam reformer, since a temperature of 575° C. is below the Tamman temperature range (the range at which bulk atoms exhibit mobility), and hence inter-metallic diffusion problems are avoided. In an exemplary implementation, the hydrogen separation membrane is preferably a film of palladium alloy and is more preferably a film of a palladium-silver alloy (77% Pd) on a porous support. Preferred porous supports include stainless steel and Inconel available from Mott Corp. As stated above, the steam reformation reaction is preferably carried at a temperature in the range of about below 625° C. more preferably below 575° C. Another advantage is that reforming at these temperatures results in the presence of un-reacted hydrocarbons in outlet gas, which is preferably in the 5 to 25 mole % range. These un-reacted hydrocarbons are combusted to provide heat to vaporize water and preheat the feed, and to run the reforming reaction as described in PCT/US02/12822, filed Apr. 23, 2002, which is herein incorporated by reference. In particular exemplary implementations, such outlet gas comprising partially reformed hydrocarbons can be fed to a solid oxide fuel cell (SOFC) to complete the reformation process. Finally, operating below 625° C., permits the use of conventional and relatively inexpensive metals such as stainless steel, as materials of construction. Inconel is available from a variety of sources, as known in the art, and is a variety of alloys which are useful for practicing the present invention. Exemplary alloys include, but are not limited to: Inconel 600 (nominal composition of essential elements: Ni(+Co) 76.4, C 0.04, Mn 0.2, Fe 7.2, S 0.007, Si 0.2, Cu 0.10, Cr 15.85); Inconel 625 (nominal composition of essential elements: Ni (+Co) 62.6 C 0.05, Mn 0.55, Fe 6.85, S 0.007, Si 0.35, Cu 0.05, Cr 20, Al 0.15, Ti 0.3, Cb(+Ta) 3.95; Inconel X (nominal composition of essential elements: Ni (+Co) 72.85, C 0.04, Mn 0.65, Fe 6.80, S 0.007, Si 0.3, Cu 0.05, Cr 15.15 Al 0.75, Ti 2.5, Cb (+Ta) 0.85). In an exemplary implementation , the steam reformer 22 incorporates a highly effective combination of three catalysts to transform a feed stream containing a C1-C4 hydrocarbon or mixtures of such hydrocarbons into hydrogen, while substantially eliminating the formation of coke residue. The first catalyst is a high-activity steam reformation catalyst. Exemplary high activity steam reformation catalysts typically have light-off temperatures in about the 350-400° C. range. Preferred high-activity steam reformation catalysts include supported, nickel-based catalysts, such as the C 11-9-09 catalyst available from Süd Chemie, Louisville, Ky. The C 11-9-09 catalyst is formed of 1-15 wt. % nickel oxide on an alumina support. The second catalyst is a coke-resistant steam reformation catalyst. Preferred coke-resistant catalysts include supported, doped, nickel-based catalysts. Representative dopants include calcium oxide, potassium oxide, calcium aluminate and combinations thereof. Suitable coke-resistant catalysts include G-91 catalyst also available from Süd Chemie. The G-91 catalyst is formed of 15-25 wt. % nickel 150° C. for 1 h, ramping to 700° C. at a ramp rate of 180° C./h and holding at 700° C. for 4 h. The relative amount of each catalyst will depend on a number of operating parameters including the particular steam reformation reactor and feed gas. For example, the relative concentration of the high activity catalyst can be increased with increasing proportion of C1 or natural gas in the feedstock, while the relative concentration of the coke-resistant catalyst can be increased with the increasing proportion of higher hydrocarbons in the feedstock. Typically, the catalysts are loaded into the steam reformer 22 in such a manner that the steam reformer reactor contains from about 10 wt. % to 70 wt. %, preferably about 20 wt. % to 60 wt. %, and more preferably about 51 wt. % of the first catalyst, about 10 wt. % to 70 wt. %, preferably about 20 wt. % to 60 wt. %, and more preferably about 46 wt. % of the second catalyst, and about 1 wt. % to 10 wt. %, preferably about 2 wt. % to 5 wt. %, and more preferably about 3 wt. % of the third catalyst. In exemplary implementations where a premium is placed on minimizing the production of coke, the coke-resistant catalyst is loaded at the entrance of the steam reformer 22, followed by the high-activity catalyst. In exemplary implementations where it is desired to enhance catalyst activity, all or part of the coke-resistant catalyst can be mixed with the high-activity catalyst, before loading into the steam reformer. The third catalyst is incorporated at adjacent the exit portion. In the case of catalysts provided as powders, the powders are packed manually, that is powders, shake/tap to allow powders to settle, fill more powders etc, until the channels 101 are fully packed. The reactor is then sealed, a gas is passed through the reactor, the reactor is opened for inspection and channels 101 are repacked if needed. When catalysts are in the form of powders, the catalyst powders are carefully packed so as to prevent the occurrence of channeling. Channeling occurs when catalyst particles are dislodged so as to expose catalyst-free pathways that offer a path of least resistance which gases will take, and therefore result in lower hydrogen production rates. EXAMPLES In the illustrative examples below, the effective hydrocarbon conversion (XHC) is defined as follows: oxide, 1-10 wt. % calcium oxide, 1-5 wt. % potassium oxide, and 20-49 wt. % calcium aluminate on an alumina support. In preferred embodiments, the activity of the supported, nickel-based catalyst is increased by including small amounts of a noble metals. In some preferred embodiments, the catalysts contain from about 1-2 wt. %, more preferably from about 0.5-1 wt. % of noble metals such as platinum, palladium and rhodium, for example. The third catalyst is a steam reformation catalyst that also promotes a water-gas shift reaction. The water-gas shift reaction is a reaction that causes water to further react with the CO produced in accordance with Equation (1), above. This not only results in the production of additional hydrogen, but it reduces the amount of CO, an undesirable byproduct of steam reformation. The water-gas shift reaction can be represented by the following equation: CO+H2O→CO2+H2 Equation (3) Suitable third catalysts are supported catalysts containing 1-3 wt. %, preferably about 0.5 wt. % to 2 wt. %, noble metal, such as platinum and/or palladium on a high surface area support. In the case of platinum or palladium, these catalysts can be prepared from dihydrogen hexachloroplatinate (IV) and tetraamine palladium (II) nitrate (both from Alfa Aesar) using an incipient wetness technique, for example. Representative supports include high surface area alumina, silica, zirconia or ceria supports, more preferably supports doped with calcia or magnesia. The latter doped supports are less acidic, and are therefore less susceptible to coke formation. A preferred high surface support contains, in weight percent (wt. %), >92 wt. % alumina, 1 wt. %, to 10 wt. % calcium oxide more preferably 1 to 5 wt. % calcium oxide and 0.5 wt. % to 5 wt. % magnesium oxide, and more preferably 0.5 wt. % to 2 wt. %, magnesium oxide. Such catalyst supports are available from Saint Gobain Norpro. The supports, typically having an initial surface area on the order of 250 m2/g, are sized mesh, preferably about 35 to 60 mesh (250 to 500 micron sized particles) prior to impregnation with the noble metal catalyst. After impregnation, the resulting supported catalyst powders are heat treated, for example heat treated at XHC=(CCO+CO2)/(Cin), where C represents carbon Example 1 Hydrogen Production Using A Plurality of Catalysts Hydrogen production from methane using a plurality of catalysts containing 46% of the coke resistant catalyst, 51% of the high activity catalyst and 3% of the steam reformation catalyst with water gas shift capabilities. The same catalyst loading was used for all examples. Hydrogen is produced from methane via the following reactions: CH4+H2O→CO+3H2 (1) CO+H2O→CO2+H2 (2) Reaction (1) is referred to as steam reforming and reaction (2) is generally referred to as the water gas shift reaction. A combination of reactions (1) and (2) yields CH4+2H2O→CO2+4H2 (4) Reaction (4) shows that the stoichiometric steam to carbon ratio (S/C) is 2. To prevent coke accumulation and promote water gas shift, an excess of steam preferably equal to 1.5 times the stoichiometric value was employed. The S/C ratio was therefore close to 3. The residence time based on reactor volume was calculated to be 0.31 to 0.34 s. Residence time is defined as the ratio of the reactor volume to the flow rate of the reactants (steam+methane) at reaction temperature at pressure. The inverse of the residence time is defined as the space velocity. This quantity corresponding to residence times of 0.31 to 0.34 s is in the 10,800 h′ to 11,500 h′ range. Methane conversion and hydrogen concentration in the dry product gas during steam reformation of methane at residence times less than 0.4 s were measured in an exemplary MesoChannel Reactor. The results are shown in FIG. 6, which is an exemplary plot of methane conversion and hydrogen concentration in the product gas (dry basis) as a function of temperature at a residence time of less than 0.31 to 0.34 s. As can be seen, both of these quantities increased with temperature in a monotonic fashion resulting conversions of 53% and hydrogen concentrations of 68% at 625° C. Carbon balance calculated as (g Cin−g Cout)/g Cin for each analysis was within +/−3% over the course of this run. Hydrogen production rates during steam reformation of methane at residence times less than 0.4 s were also measured and the results are shown in FIG. 7 which reports a diagram illustrating the hydrogen production rates during the reaction temperatures of 600° C. and 625° C. As shown in FIG. 7 a hydrogen production rate of about 300 sccm (flow rate at STP) was sustained for more than 30 hours. This result points to excellent catalyst stability under the reaction conditions employed. The up-stream reaction pressure during these measurements varied from 1.7 to 2.8 psig. Operating at such low pressures while at space velocities of >10,000 h−1 and with catalyst powders is made possible using the MesoChannel reactor architecture described above. Carbon dioxide, carbon monoxide and methane concentrations in the dry product gas during steam reformation of methane at residence times less than 0.4 s was also measured in the MesoChannel Reactor and the results are shown in FIGS. 8 and 9. FIG. 8 shows the concentrations of hydrogen, carbon dioxide and methane while FIG. 9 shows the carbon monoxide levels in the reactor effluent gas (dry basis). The flat trends seen in these figures also support excellent stability. Notice in particular (FIG. 9) that the concentration of CO is only about 4% at both 600° C. and 625° C. Such low levels of CO indicates that the water gas shift reaction (reaction 2) is favored due to the addition of excess steam in the feed and due to the selection and configuration of proper catalysts. Experiments were also carried out to measure equilibrium methane conversion vs. experimental values in the MesoChannel Reactor. The experimental results were obtained during steam reformation of methane at residence times less than 0.4 s and are shown in FIG. 10, wherein a comparison of equilibrium methane conversions and measured methane conversions is shown. The equilibrium compositions were calculated by minimizing the Gibbs free energy of a mixture consisting of methane, carbon oxide, carbon dioxide, hydrogen and water and at the same pressure and S/C ratio as that corresponding to the experimental run. The equilibrium hydrogen concentrations vs. experimental values on a dry basis, during steam reformation of the methane shown in FIG. 10 was also measured. The results are reported on FIG. 11, which shows a comparison of equilibrium and experimental hydrogen concentrations dry basis vs. experimental values and indicates that the operating conditions are away from equilibrium, and therefore suggests that higher hydrogen production rates (>300 sccm) are possible as conditions are chosen to approach equilibrium using the same reactor. The reaction was stopped by gradually replacing methane flow with hydrogen flow, while reducing the temperature. Water was cut-off when the reactor temperature reached about 350° C. and the reactor was cooled to room temperature under hydrogen flow. On reaching room temperature, hydrogen flow was cut-off and the reactor was idled. Example 2 Hydrogen Production by the Steam Reforming of Methane after Reactor Idling for more than 2 Months. The reactor with the same catalyst loading was again heated to repeat methane steam reforming as described in Example 1, after an idling time of more than 2 months. a period during which the reactor remains at room temperature with no gas flow is referred to as idling. The start-up procedure as described in Example I was followed. Table I compares conversions (X) and outlet gas compositions obtained at 550° C. and 575° C. during this run with the values obtained during the run described Exampe 1, in mole fraction, dry basis. As can be seen, there is good agreement between the two runs, pointing to good catalyst stability, during one thermal cycle. The thermal cycle consisted of cooling from 625° C. to room temperature at the end of the run described in Example 1, and heating from room temperature to 550° C. and then to 575° C. during the start-up of the run in Example 2. TABLE 1 Run Temp (° C.) X, CH4 H2 CO CH4 CO2 Example 1 550 35.44 59.17 1.74 26.36 12.73 575 41.07 62.13 2.55 22.32 13.00 Example 2 550 40.87 57.29 2.24 27.31 13.15 575 45.58 62.45 3.16 20.43 13.95 Example 3 Hydrogen Production by the Steam Reforming of Propane The reactor that was in operation for methane reforming as described in Example 2, was then utilized for propane reforming by simply replacing methane flow by propane flow while the reactor temperature was at 575° C. The propane used was of a certified purity grade (99.98%, Matheson). Minor constituents that were present in the propane gas feed are listed in Table 2. No attempt was made to remove the sulfur that was present in the propane feed. TABLE 2 Impurity Concentration (ppm) 1. n-butane 0.4 2. Ethane 1.4 3. Ethylene <0.5 4. Isobutane 0.4 5. Methane <0.5 6. Nitrogen 1.8 7. Oxygen <0.5 8. Propylene <0.5 9. Sulfur <0.5 10. Water <1 The flow rate of propane and steam was controlled to yield a feed SIC ratio of 2.86, which is close to the S/C value of 3 that was used for methane reforming as described in Example 1. The residence time at reaction temperature and pressure was 0.24 seconds, and the reactor pressure was in the 2-3 psig range. The composition of the outlet gas was monitored continuously for about 35 hours and was found to be as shown in FIGS. 12A and 12B. The hydrogen content of the product gas was about 64% (H2, equilibrium 66%) and remained fairly steady during this period. The CO and CO2 contents were about 4% (CO, equilibrium=7%) and about 18% (CO2, equilibrium=17%) respectively, indicating the occurrence of the water gas shift reaction. Average hydrocarbon conversion was 41% (equilibrium conversion=70%), and reformed gas production was at the rate of about 326 sccm. Example 4 Hydrogen Production by the Steam Reforming of Butane The reactor that was in operation for propane steam reforming as described in Example 3, was then utilized for producing hydrogen via the steam reforming of butane by simply replacing the propane flow with butane flow, while the reactor temperature was at 575° C. The butane that was used was commercial purity grade (99%, Matheson) and was stored as a liquid under 150 psig nitrogen head pressure. No attempt was made to pre-treat the butane feed prior to feeding into the reactor. The flow rate of butane and steam was controlled to yield a feed with a S/C ratio of 2.87. The residence time at reaction temperature and pressure was about 0.26 seconds. The composition of the reactor outlet gas was monitored continuously for a period of about 33 hours and was found to be as presented in FIGS. 13A and 13B. It can be seen that the hydrogen content in the product gas remained fairly steady at about 64% (H2, equilibrium=65.5%) during this period, while the CO content remained at under 4% (CO. equilibrium=7%). The average hydrocarbon conversion over the 33 hour testing period was about 32% (equilibrium conversion 72.5%), while reformed gas was produced at the rate of about 335 sccm. As mentioned above, butane was stored as a liquid and was vaporized using an exemplary vaporizer system 300 as shown in FIG. 14. The vaporizer system 300 comprises a butane storage 302 connected with a pressure sensor 301, and with a reactor 304 through a heat exchanger 303. The butane is fed into the reactor 304 through the conduit 307 and the product gases exiting reactor 304 are directed to an exhaust 309 through conduit 308. Conduit 308 originates heat exchange coils 306 wrapping around butane storage 302 and directed to an exhaust 310. A first detector 305 in the conduit 306 and a second detector in the conduit 308 are provided and associated to pressure sensor 301 to detect pressure in the various portions of the system. Such an arrangement was adopted to circumvent flow fluctuations that would arise due to a vapor/liquid flow of butane. The temperature of the heating bath was maintained at about 44° C. Butane that was stored as a liquid was metered through a needle valve into an intermediate storage vessel that was provided with a coil of copper tubing that was wound around it. Water from a constant temperature bath was circulated through the coil in order to provide heat. Butane from the intermediate storage vessel was routed through a back pressure regulator and through a coil of copper tubing that was immersed in the constant temperature bath and then to a mass flow controller. In a hydrogen generation apparatus as shown in FIG. 1, butane can be warmed by utilizing the heat from hot streams such the combustion exhaust gases exiting the combustors, for example stream 54 that exits the vaporizer. When liquid butane is used for producing hydrogen for portable fuel cell applications, a process flow arrangement, as exemplarily depicted schematically in FIG. 14, can be used to insure a well regulated flow of butane into the reactor. Such an arrangement can be particularly beneficial when the reactor is of the form of a hydrogen-separating membrane reactor, which typically operates at pressures in the 40 to 60 psig range to insure sufficient hydrogen flow through the membrane. At 20° C. , butane has a vapor pressure of only 15 psig, but at 50° C., butane has a vapor pressure of 58 psig, which is sufficient to meet the needs of a membrane reactor. Example 5 Hydrogen Production by the Steam Reforming of Coleman Powermax Fuel Fuels that are available in canisters, such as the Powermax fuel which is sold by the Coleman Company (Wichita, Kans.), are widely used during the pursuit of outdoor activities to power portable devices such as stoves. The Powermax fuel is made up of approximately 60% butane and 40% propane. It is inexpensive and is stored in lightweight canisters. The fuel has a higher vapor pressure than pure butane due to the propane blend, and is well suited for operation at colder temperatures. These fuels typically contain sulfur additives such as light mercaptans and with a total sulfur content usually in the about 15 to 25 ppm range. The reactor that was in operation for steam reforming of butane, as described in Example 4, was then utilized for producing hydrogen via the steam reforming of the Powermax fuel by simply replacing the propane flow with Powermax fuel flow, while the reactor temperature was at 575° C. In this case, however, the fuel was routed through an adsorber (bed as described above) to remove sulfur. Adsorbents that are commonly used for sulfur removal include activated charcoal, molecular sieves and zinc oxide. More preferably, the adsorbent is an activated carbon that contains transition metals like copper and iron. Such adsorbents are cheap, efficient and are regenerable, unlike the zinc oxides. The adsorbent utilized here was composed of 90-100 wt.-% activated carbon, 0-10 wt.-% ferric oxide and 0-10 wt.-% cupric oxide. The adsorbent was supplied by Nucon International (Columbus, Ohio), and is capable of removing H2S, CS2, light mercaptans, t-butyl mercpatans, sulfides, disulfides and hydrogen selenide with adsorption capacities of 15 wt.-% sulfur. The adsorbents particles were in the form of extrudates that were 0.056 inch in diameter and 0.1 inch in length. The adsorber bed was a 1.5 inch ID (internal diameter)×12 inch tube that was packed with 175 g of the adsorbent. If the fuel flow rate is so chosen to correspond to a hydrogen production of about 200 sccm, and assuming that the fuel contains 50 ppm of light sulfur compounds, the loading of 175 g of this adsorbent should be capable of removing sulfur for more than 5 years of continuous operation. The adsorbent bed can be sized in such a manner to meet the requirements of hydrogen generation for stationary or portable fuel cell applications. The adsorbent bed used in this example resulted in a L/Dp (length to particle diameter) ratio of about 210 and D/Dp (diameter of tube to particle diameter) of 27. Desired values of these ratios are about 50 to 100 and about 5 to 10, respectively, to insure uniform plug flow behavior. The control valve of the fuel canister was adapted to incorporate a ⅛″ stainless tubing that contained a needle valve. Fuel was routed through a needle valve into the adsorber. The outlet stream. of the adsorber passed through a vaporizing coil that was maintained at about 44° C., and was metered using a mass flow controller into the reactor system. The flow rate of the fuel and steam was controlled to yield a feed with a S/C ratio of 2.26. The residence time at reaction temperature and pressure was about 0.25 seconds. The composition of the reactor outlet gas was monitored continuously for a period of about 20 hours and was found to be as shown in FIGS. 15A and 15B. It can be seen from FIG. 15A that the hydrogen content in the product gas remained fairly steady at about 60% (H2 at equilibrium=64%) during this period, while the CO content remained at about 4% (CO content at equilibrium 7%). The average hydrocarbon conversion was about 31% (equilibrium conversion=67.5%), while reformed gas was produced at the rate of about 345 sccm over a 20 hour testing period. Example 6 Steam Reforming of Propane: Long Term Stability Test As demonstrated in examples 1 to 5, hydrogen was produced by successively switching or “hot swapping” to different hydrocarbons: from methane for about 33 h, to propane for about 35 hours, to butane for about 33 hours and to Powermax fuel for about 20 hours. To further demonstrate that the same catalyst possesses the ability to reform various hydrocarbons to hydrogen, another test was conducted for a period that was in excess of 240 h and is described below. The reactor that was in operation for Powermax fuel reforming as described in Example 5, was then utilized for propane reforming by simply replacing Powermax fuel flow by propane flow while the reactor temperature was at 575° C. The propane used was of the certified purity grade (99.98%, Matheson) and was the same fuel as used in Example 2. The flow rate of propane and steam was controlled to yield a feed with a S/C ratio of 2.55 (=2.86 in Example 3). The residence time at reaction temperature and pressure was 0.20 seconds (=0.24 in Example 3), and the reactor pressure was in the 2-3 psig range. The composition of the outlet gas was monitored continuously for more than 240 h hours and was found to be as shown in FIGS. 16A and 16B. The hydrogen content (FIG. 16A) of the product gas was between 56 to 59% (H2 at equilibrium=64%) and remained fairly steady during this period. The CO and CO2 contents were about 4% (CO at equilibrium=7%) and about 16% (CO2 at equilibrium=17%) respectively. The average propane conversion was calculated to be about 30% (equilibrium conversion=67.5%), while reformed gas was produced at about 320 sccm over this period. Generally, reformed gas contains, on average, about 60 to 75 wt. % hydrogen, 10 to 15 wt. % carbon dioxide, up to 10 wt. % carbon monoxide and 15 to 30 wt. % unreacted fuel. When pure hydrogen is needed, for example for PEM fuel cell applications, the hydrogen is separated from the other gases by, for example, use of a hydrogen membrane reactor. In some exemplary implementations, the unreacted fuel is then recycled to provide at least a portion of the fuel for the combustors integrated with the vaporizer 18, the preheater 20 and/or the steam reformer 22. For generating power using solid oxide fuel cells, the dry reformed stream can be directly routed to the solid oxide fuel cell. For exemplary implementations in which a fuel cell is added to the system to generate electricity from the hydrogen produced, the preferred fuel cell is a PEM fuel cell. The hydrogen produced can be routed to other hydrogen using apparatus, such as welding and other metal working apparatus. When pure hydrogen is required, preferably, the hydrogen generator 10 will generate hydrogen on demand and in those exemplary implementations where the hydrogen is to be used immediately after it is generated a hydrogen reservoir is not required. However, there are inefficiencies inherent in a hydrogen generating cycle that comprises a series of short periods of operation followed by long periods of inactivity, because during the start up phase, the fuel is being used to bring the system up to an operating temperature rather than for generating hydrogen. Therefore, in some exemplary implementations, a hydrogen reservoir (not shown) is employed to store hydrogen not currently required, so that while the system is at operating temperature, the fuel can be employed to generate hydrogen for later use, rather than to bring the system to operating temperature. Since the filling of such hydrogen reservoirs, such as hydrides, requires that hydrogen be supplied at pressure, typically between 100 and 300 psig, a compressor should be used to increase the pressure of hydrogen that is diverted to the storage device. Alternately, the operating pressure of the reformer can be increased to suit the pressure requirements of charging the hydrides. In summary, a method for generating hydrogen, which comprises providing a hydrogen reactor chamber; and providing a plurality of catalysts within said hydrogen reactor chamber, in a staged catalyst medium; a method to generate hydrogen by steam reformation of a hydrocarbon fuel comprising providing a steam reformer and providing a plurality of catalysts within said steam reformer, in a staged catalyst medium; a hydrogen generation apparatus comprising at least one of a steam reformer and a reaction chamber comprising a plurality of catalysts in a staged catalyst medium; a method for manufacturing a hydrogen generation apparatus, comprising: providing a reaction chamber and/or a steam reformer; and providing within said element a plurality of catalysts in a staged catalyst medium. Although the present invention has been described in connection with the preferred form of practicing it, those of ordinary skill in the art will understand that many modifications can be made thereto without departing from the spirit of the present invention. Accordingly, it is not intended that the scope of the invention in any way be limited by the above description.

<SOH> BACKGROUND OF THE INVENTION <EOH>The growing popularity of electronic devices has produced an increased demand for electrical power sources to energize these devices. At present, storage or rechargeable batteries are typically used to provide independent electrical power sources for electronic devices. However, the amount of energy that can be stored in storage or rechargeable batteries is insufficient to meet the need of certain applications. Fuel cells, including hydrogen/air fuel. cells (H/AFCs) have enormous potential as a replacement for batteries. Fuel cells can operate on very energy-dense fuels. Some fuel cell-based power supplies offer high energy-to-weight ratios compared with even state-of-the-art batteries. Functionally, fuel cells generate electricity by reacting hydrogen with oxygen to produce water. For example, in a PEM H/AFC hydrogen atoms pass through a membrane as H+ while the electrons travel around the membrane, the H+s join with oxygen, on the otherside of the membrane to form water. Since oxygen can typically be obtained from the ambient atmosphere, only a source of hydrogen must be provided to operate a fuel cell. Merely providing compressed hydrogen is not always a viable option, because of the substantial volume that even a highly compressed gas occupies. Liquid hydrogen, which occupies less volume, is a cryogenic liquid, and a significant amount of energy is required to maintain the extremely low temperatures required to maintain it as a liquid. Furthermore, there are safety issues involved with the handling and storage of hydrogen in the compressed gas form or in the liquid form. Among the most desirable alternative hydrogen sources is hydrogen produced by the steam reformation of hydrocarbons, particularly C 1 -C 4 hydrocarbons. For example, C 1 , methane, as natural gas, and C 3 , propane, are used for residential, mobile home and recreational services, while propane and C 4 , butane, are used as fuels for backpack stoves. Following are the reaction equations for the steam reforming method, where methane is the feedstock: in-line-formulae description="In-line Formulae" end="lead"? CH 4 +H 2 O→CO+3H 2 Equation (1) in-line-formulae description="In-line Formulae" end="tail"? in-line-formulae description="In-line Formulae" end="lead"? CH 4 +2H 2 O→CO 2 +4H 2 Equation (2) in-line-formulae description="In-line Formulae" end="tail"? It is a drawback of the reformation of such hydrocarbon fuels, that coke, a solid residue which reduces the activity and lifetime of the steam reformation and catalyst and is undesirable in a fuel cell application, is formed. Consequently, there is a desideratum for an apparatus and method that has the flexibility to effectively and efficiently generate hydrogen from C 1 -C 4 hydrocarbon fuels without necessitating a change in the catalyst, while minimizing the production of coke residue.

<SOH> SUMMARY OF THE INVENTION <EOH>Now in accordance with this invention there has been found a hydrogen generation apparatus for use with fuel cells and other applications wherein generation of hydrogen is required or desirable. According to a first aspect a method for generating hydrogen is disclosed, the method comprising providing a reactor chamber; providing a plurality of catalysts within the reactor chamber to form a staged catalyst medium; and passing a fuel feed stream, such as a hydrocarbon fuel stream, in the reactor chamber to produce hydrogen or a hydrogen containing product gas. Providing a plurality of catalysts within the reactor chamber can be performed by packing or loading the plurality of catalysts in the staged catalyst medium within the chamber. A staged catalyst medium is a medium comprising a series of distinct zones or portions, each zone or portion comprising a distinct catalyst or combination thereof having a unique definitive characteristic. A definitive characteristics, is a characteristic of the catalyst or combination thereof identifying a physical and/or chemical property of the catalyst or combination thereof which is associated with the hydrogen generation as performed in the apparatus. Zones boundaries may vary. Zone boundaries may be characterized by an abrupt end to the catalysts, may be characterized by a decreasing or increasing gradient of one or more catalysts or catalytic activity, or may be characterized by any combination thereof. Each zone or portion comprises a catalyst or combination thereof such that the definitive characteristic of the catalyst or combination thereof is unique, i.e. not presented by catalysts or combination thereof comprised in other zones or portions of the staged catalyst medium. A definitive characteristic of the catalyst in each zone or portion and the location of the zones or portions in the staged catalyst medium is a function of a desired effect to be performed in the zone or portion, the effect associated with the hydrogen generation performed in the reactor, the structure and/or the operation mode of the reactor. In some exemplary implementations, the plurality of catalysts are packed or loaded in the staged catalyst medium within the reactor chamber such that the feed stream passed in the reactor chamber is exposed to the plurality of catalysts in a predetermined sequential manner. The predetermined sequential manner can be determined in view of several factors associated with the desired production of hydrogen, such as the selected hydrogen generating reaction to be performed in the reactor, presence and location of pre-reformation zones in the reactor, selection of operating mode of the reactor. Accordingly, in exemplary implementations wherein the hydrogen generation is performed by steam reformation, providing a plurality of catalysts within the reactor chamber in a staged catalyst medium can be performed such that a steam reformation catalyst is located in the staged catalyst medium in a zone adjacent the entrance portion and/or typically exit portion of the hydrogen reactor chamber, the catalysts promoting a water-gas shift reaction. Also, in exemplary implementations, wherein a pre-reformation zone is included in the chamber, providing a plurality of catalysts within the reactor chamber in a staged catalysts medium can be performed such that a steam reformation catalysts is located in the staged catalyst medium in a zone located in the prereformation zone. In exemplary implementations, wherein a hydrogen separation membrane is included in the reactor, providing a plurality of catalysts within the reactor chamber can be performed such that hydrogen that is contained in the product gas can be separated through a palladium based membrane that is located either internal or external to the reactor. Additionally, providing a plurality of catalysts within the reactor chamber in a staged catalyst medium can be performed such that a predetermined catalyst is packed or loaded in the staged catalyst medium in a zone located in a portion of the reactor wherein the temperature is adjusted to enhance the performance of the catalysts in the reactor. Providing a plurality of catalysts within the reactor chamber in a staged catalyst medium can also be performed such that staged catalyst medium includes a first portion having at least one of a high-activity steam reformation catalyst and a coke-resistant steam reformation catalyst and a second portion having a steam reformation catalyst that promotes a water-gas shift reaction, located adjacent exit portion of the hydrogen reactor chamber. Providing a plurality of catalysts within the reactor chamber in a staged catalyst medium can be performed so that the staged catalyst medium comprises a plurality of catalysts provided and comprised of at least one of a high-activity steam reformation catalyst and a coke-resistant steam reformation catalyst. In some exemplary implementations the plurality of catalysts is further comprised of a steam reformation catalyst that promotes a water-gas shift reaction. Providing a plurality of catalysts within the reactor chamber in a staged catalyst medium can be performed so that the coke-resistant steam reformation catalyst is loaded at an entrance of the hydrogen reactor chamber, followed by a high-activity steam reformation catalyst. Alternatively, all or part of the coke-resistant steam reformation catalyst can be mixed with the high-activity steam reformation catalyst before loading into the hydrogen reactor chamber. Providing a plurality of catalysts within the hydrogen generating apparatus in a staged catalyst medium and/or passing a feed stream in the reactor chamber can also be performed such that the high reforming and water gas shift activity features of at least one catalyst is balanced with resistance to coking. The method can also comprise adjusting the operating parameters of the hydrogen generating apparatus to enhance the performance of the plurality of catalyst in the staged catalyst medium. In particular, the temperature of the reactor can be adjusted so that the zone including a determined catalyst is brought at the desired operating temperature of the catalysts for example by employing heat exchange. According to a second aspect a hydrogen generation apparatus is disclosed, the apparatus comprising a reactor chamber, the reactor chamber comprising a plurality of catalysts in a staged configuration, wherein the plurality of staged catalysts is provided in a staged catalyst medium. In particular, the plurality of catalysts can be located in the reaction chamber in any of the staged catalyst medium herein described. The staged catalyst medium can also be located in other portions of the hydrogen generating apparatus, such as pre-reformer, wherein hydrogen producing reactions and/or additional reactions associated with hydrogen production in the apparatus are performed. According to a third aspect, a hydrogen generating apparatus wherein hydrogen is generated by steam reformation of a hydrocarbon fuel is disclosed. The apparatus comprises a steam reformer wherein a reaction resulting in steam reformation of a hydrocarbon fuel is performed, the steam reformer including a portion having a plurality of steam reformation catalysts disposed therein. The plurality of steam reformation catalysts can be provided in a staged configuration, wherein the plurality of catalysts are included in a staged catalyst medium. In particular, the plurality of catalysts can be located in the steam reformer in any of the staged catalyst medium herein described. The staged configuration can in particular include a staged catalyst medium including a coke-resistant steam reformation catalyst loaded at an entrance of the steam reformer. Furthermore, the plurality of steam reformation catalysts in the staged catalyst medium can include at least two of a high-activity steam reformation catalyst, a coke-resistant steam reformation catalyst and a steam reformation catalyst which promotes a water-gas shift reaction. The high-activity steam reformation catalyst can be a supported nickel-based catalyst and the coke-resistant steam reformation catalyst can be a supported doped nickel-based catalysts. In an embodiment, the supported doped nickel-based catalyst can be comprised of at least one of calcium oxide, potassium oxide and calcium aluminate or combinations thereof. In some exemplary implementations the supported doped nickel-based catalysts is further comprised of at least one noble metal, such as at least one of platinum, palladium, and rhodium or combination thereof. The coke-resistant stream reformation catalyst can be loaded at an entrance of the steam reformer, followed by the high-activity steam reformation catalyst. According to a fourth aspect, a method for generating hydrogen by steam reformation of a hydrocarbon fuel is disclosed. The method comprises providing a steam reformer; providing a plurality of catalysts within the steam reformer in a staged catalyst medium; passing a hydrocarbon fuel. feed stream in the steam reformer to obtain a hydrogen containing reformed stream, the reformed stream purified to produce hydrogen. Providing a plurality of catalysts in the steam reformer to. form a staged catalysts medium can include locating the plurality of catalysts to form a staged catalyst medium in the steam reformer in any of the staged catalyst medium herein described wherein the chemical and/or physical activity associated with hydrogen production is also associated to steam reformation reactions. Purification of the hydrogen can be achieved by hydrogen separation membranes that are situated either internal or external to the steam reformer. The feed stream of hydrocarbons can be a fuel having at least one of a C 1 -C 4 hydrocarbon or mixture or oxygenate thereof. Catalysts may be provided on a number of useful carriers, such as foams, monoliths, felts, pellets or powders, or any combination thereof. According to a fifth aspect, a method for manufacturing a hydrogen generation apparatus is disclosed, the method comprises providing an element or component of the hydrogen generation apparatus wherein a reaction associated with hydrogen production is performed, such as a reaction chamber; and providing within said element a plurality of catalysts to form a staged catalyst medium, the staged catalyst medium comprising a series of distinct zones or portions, each zone or portion comprising a distinct catalyst or combination thereof. The reaction chamber is preferably a steam reformer. The hydrogen generation apparatuses herein disclosed can also comprise a other elements or components identifiable by a person skilled in the art, such as fuel supply, a water supply, an oxygen supply, an air intake, and a vaporizer. Each of the elements included in the hydrogen generation apparatus according to the disclosure are connected to other elements by related lines identifiable by a person skilled in the art. According to the teachings of the present invention, exemplary methods and apparatuses can provide for at least 300 sccm of a reformed stream containing about 60% hydrogen produced in conjunction with residence times of less than about 0.5 sec, preferably less than about 0.4 sec. In a particular embodiment, the at least one C 1 -C 4 hydrocarbon is propane and provides hydrogen production at residence times of about 0.15 to about 0.30 sec, preferably from about 0.20 to about 0.28 sec at about 575° C . Such a reformed gas stream containing hydrogen, when routed to a fuel cell such as a solid oxide fuel cell (SOFC), is capable of generating about 15 to 25 W of power based on the characteristics of the SOFC. The features believed to be novel are set forth within. However, the features both as to configuration, and method of operation, and the advantages thereof, may be best understood by reference to the following descriptions taken in conjunction with the diagrams, figures and accompanying drawings.

20070717

20131231

20080103

68710.0

B01J802

CHANDLER, KAITY V

HYDROGEN GENERATION APPARATUS INCORPORATING A STAGED CATALYST AND METHOD FOR USING SAME

UNDISCOUNTED

ACCEPTED

B01J

ACCEPTED

DRIVING CIRCUIT OF A LIQUID CRYSTAL DISPLAY PANEL AND RELATED DRIVING METHOD

A method for driving a liquid crystal display (LCD) panel includes receiving continuously a plurality of frame data, generating a plurality of data impulses for each pixel every frame period according to the frame data, and applying the data impulses to a liquid crystal device of a pixel within a frame period via the data line connected to the pixel in order to control a transmission rate of the liquid crystal device.

1. A method for driving a liquid crystal display (LCD) panel, the LCD panel comprising: a plurality of scan lines; a plurality of data lines; and a plurality of pixels, each pixel being connected to a corresponding scan line and a corresponding data line, and each pixel comprising a liquid crystal device and a switching device connected to the corresponding scan line, the corresponding data line, and the liquid crystal device, and the method comprising: receiving continuously a plurality of frame data; generating a plurality of data impulses for each pixel within every frame period according to the frame data; and applying the data impulses to the liquid crystal device of one of the pixels within one frame period via the data line connected to the pixel in order to control a transmission rate of the liquid crystal device of the pixel. 2. The method of claim 1 further comprising: delaying the frame data to generate a plurality of corresponding delayed frame data; and comparing current frame data and corresponding delayed data to determine voltage values of the data impulses when generating the data impulses. 3. The method of claim 2 wherein the data impulses are a first data impulse and a second data impulse applied to the liquid crystal device of the pixel in sequence within the frame period. 4. The method of claim 3 further comprising: determining a difference between the first data impulse and the second data impulse according to the current frame data and the corresponding delayed frame data. 5. The method of claim 1 further comprising: applying a scan line voltage to the switch device of the pixel via the scan line connected to the pixel in order to have the data impulses be applied to the liquid crystal device of the pixel. 6. The method of claim 1 wherein each frame data comprises a plurality of pixel data, and each pixel data corresponds to a pixel. 7. A driving circuit for driving an LCD panel, the LCD panel comprising: a plurality of scan lines; a plurality of data lines; and a plurality of pixels, each pixel being connected to a corresponding scan line and a corresponding data line, and each pixel comprising a liquid crystal device and a switching device connected to the corresponding scan line, the corresponding data line, and the liquid crystal device, the driving circuit comprising: a blur clear converter for receiving frame data every frame period, each frame data comprising a plurality of pixel data and each pixel data corresponding to a pixel, the blur clear converter delaying current frame data to generate delayed frame data and generating a plurality of overdriven pixel data within every frame period for each pixel; a source driver for generating a plurality of data impulses to each pixel according to the plurality of overdriven pixel data generated by the blur clear converter and applying the data impulses to the liquid crystal device of the pixel via the scan line connected to the pixel within one frame period in order to control transmission rate of the liquid crystal device; and a gate driver for applying a scan line voltage to the switch device of the pixel so that the data impulses can be applied to the liquid crystal device of the pixel. 8. The driving circuit of claim 7 wherein the blur clear converter further comprises: a multiplier for multiplying a frequency of a control signal to generate a multiplied signal; a first image memory for delaying the pixel data for a frame period; a processing circuit for generating the plurality of overdriven pixel data according to the pixel data and the pixel data delayed by the first image memory; a second image memory for storing the overdriven pixel data; a memory controller for controlling the second image memory according to the multiplied signal to output the plurality of overdriven pixel data to any pixel so that the source driver generates the data impulses to each pixel within one frame period according to the overdriven pixel data output by the second image memory. 9. The driving circuit of claim 7 wherein the blur clear converter further comprises: a multiplier for multiplying a frequency of a control signal to generate a multiplied signal; a first image memory for receiving and temporarily storing the pixel data; a second image memory for delaying the pixel data stored and output by the first image memory for a frame period; a third image memory for delaying the pixel data stored and output by the second image memory for a frame period; a memory controller for controlling the second image memory and the third image memory according to the multiplied signal; a processing circuit for generating the plurality of overdriven pixel data according to the pixel data delayed and output by the second image memory and the third image memory; and a comparing circuit for comparing the pixel data delayed by the second image memory with the pixel data delayed by the third image memory in order to determine data values of the overdriven pixel data generated by the processing circuit.

BACKGROUND OF INVENTION 1. Field of the Invention The invention relates to a driving circuit of a liquid crystal display (LCD) panel and its related driving method, and more particularly, to a driving circuit for applying over two data impulses to a pixel electrode within one frame period, and its related driving method. 2. Description of the Prior Art A liquid crystal display (LCD) has advantages of lightweight, low power consumption, and low divergence and is applied to various portable equipment such as notebook computers and personal digital assistants (PDAs). In addition, LCD monitors and LCD televisions are gaining in popularity as a substitute for traditional cathode ray tube (CRT) monitors and televisions. However, an LCD does have some disadvantages. Because of the limitations of physical characteristics, the liquid crystal molecules need to be twisted and rearranged when changing input data, which can cause the images to be delayed. For satisfying the rapid switching requirements of multimedia equipment, improving the response speed of liquid crystal is desired. Generally when driving an LCD, a driving circuit receives a plurality of frame data and then generates corresponding data impulses, scan voltages, and timing signals, according to the frame data, in order to control pixel operation of the LCD. Each of the frame data includes data for refreshing all of the pixels within a frame period; thus each of the frame data can be regarded as including a plurality of pixel data, and each of the pixel data is for defining the gray level that a pixel is required to reach within a frame period. In the general standard, each pixel can switch among 256 (28) gray levels, thus each of the pixel data is 8 bits in length. Please refer to FIG. 1 showing a timing diagram of pixel data values varying in accordance with the frames. When driving a pixel, the driving circuit receives a plurality of pixel data used for driving the pixel in sequence. As shown in FIG. 1, GN, GN+1, GN+2 are the pixel data received in frame periods N, N+1, N+2, and the driving circuit determines the gray level of the pixel in the frame periods N, N+1, N+2 according to the values of the pixel data GN, GN+1, GN+2. In general, the larger the value of the pixel data is, the larger the gray level is. The driving circuit generates a data impulse corresponding to a frame period according to the pixel data GN, GN+1, GN+2, and applies the pulse to a pixel electrode of the corresponding pixel to have the pixel be in the appropriate gray level as required within each frame period. Please refer to FIG. 2 showing a timing diagram of different transmission rates of a pixel, varying in accordance with the frames. Two curves C1, C2 are measured when the driving circuit changes the transmission rate from T1 to T2 beginning at frame period N. The curve C1 shows the transmission rate of a pixel not overdriven corresponding to the frames, and the curve C2 shows the transmission rate of the pixel overdriven corresponding to the frames. The U.S. published application No. 2002/0050965 is one of the references of the conventional overdriving method. There is a time delay when charging liquid crystal molecules, so that they cannot twist at a predetermined angle at a predetermined transmission rate. As shown by the curve C1, in the case of not being overdriven, the transmission rate cannot reach a predetermined level in the frame period N but has to wait until the frame period N+2. Such a delay causes blurring. In order to improve that, some conventional LCD are overdriven, which means applying a higher or a lower data impulse to the pixel electrode to accelerate the reaction speed of the liquid crystal molecules, so that the pixel can reach the predetermined gray level in a predetermined frame period. As shown by the curve C2, in the case of being overdriven, although the reaction speed of the liquid crystal molecules is faster than in case of not being overdriven, the transmission rate has to wait until frame period N+1 to reach T2. Thus, the requirement of reaching T2 in the frame period N still remains unsatisfied. SUMMARY OF INVENTION It is therefore a primary objective of the claimed invention to provide a driving circuit of an LCD panel and its relating driving method to solve the problem mentioned above. Briefly, the present invention provides a method for driving an LCD panel. The LCD panel includes a plurality of scan lines, a plurality of data lines, and a plurality of pixels. Each pixel is connected to a corresponding scan line and a corresponding data line, and each pixel includes a liquid crystal device and a switching device connected to the corresponding scan line, the corresponding data line, and the liquid crystal device. The method includes receiving continuously a plurality of frame data, generating a plurality of data impulses for each pixel in every frame period according to the frame data and applying the data impulses to the liquid crystal device of one of the pixels within one frame period via the data line connected to the pixel in order to control the transmission rate of the liquid crystal device of the pixel. The present invention further provides a driving circuit for driving an LCD panel including a blur clear converter for receiving frame data every frame period, each frame data comprising a plurality of pixel data and each pixel data corresponding to a pixel, the blur clear converter delaying current frame data to generate delayed frame data and generating a plurality of overdriven pixel data in every frame period for each pixel; a source driver for generating a plurality of data impulses to each pixel according to the plurality of overdriven pixel data generated by the blur clear converter and applying the data impulses to the liquid crystal device of the pixel via the scan line connected to the pixel in order to control the transmission rate of the liquid crystal device; and a gate driver for applying a scan line voltage to the switch device of the pixel so that the data impulses can be applied to the liquid crystal device of the pixel. These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a timing diagram of the pixel data values varying in accordance with the frames according to the prior art. FIG. 2 is a timing diagram of different transmission rates of the pixel varying in accordance with the frames. FIG. 3 is a block diagram of a driving circuit and an LCD panel according to the present invention. FIG. 4 is a circuit diagram of the LCD panel. FIG. 5 is a timing diagram of pixel data values varying in accordance with frames. FIG. 6 is a timing diagram of the transmission rate of the pixel varying in accordance with the frames. FIG. 7 is a block diagram of the blur clear converter according to the first embodiment of the present invention. FIG. 8 is a block diagram of the blur clear converter according to the second embodiment of the present invention. FIG. 9 is a timing diagram of original pixel data received by the blur clear converter varying in accordance with the frames. FIG. 10 is a timing diagram of overdriven pixel data generated by the blur clear converter varying in accordance with the frames. DETAILED DESCRIPTION Please refer to FIG. 3 showing a block diagram of a driving circuit 10 and an LCD panel 30 according to the present invention. The driving circuit 10 is for driving the LCD panel 30, which includes a signal controller 12, a blur clear converter 14, a timing controller 16, a source driver 18, and a gate driver 20. The signal controller 12 is for receiving composite video signals Sc, which includes frame data and timing data for driving the LCD panel 30, and processing the composite video signals Sc to separate them into frame signals G and control signals C. Subsequently, the blur clear converter 14 continuously receives the control signals C and the frame data included in the frame signals G and generates processed frame signals G including a plurality of overdriven data according to the frame data. The timing controller 16 controls the source driver 18 and the gate driver 20 according to the frame signals G and the control signals C so that the source driver 18 and the gate driver 20 generate corresponding data line voltages and scan line voltages according to the plurality of overdriven data included in the frame signals G in order to drive the LCD panel 30 to generate images corresponding to the composite video signals Sc. Please refer to FIG. 4 showing a circuit diagram of the LCD panel 30. The LCD panel 30 includes a plurality of scan lines 32, a plurality of data lines 34, and a plurality of pixels 36. Each pixel 36 is connected to a corresponding scan line 32 and a corresponding data line 34, and each pixel 36 has a switching device 38 and a liquid crystal device 39 a.k.a. a pixel electrode. The switching device 38 is connected to the corresponding scan line 32 and the corresponding data line 34, and the source driver 18 and the gate driver 20 control the operation of each pixel 36 via the scan line 32 and the data line 34. To drive the LCD 30, scan voltages are applied to the scan lines 32 to turn on the switching devices 38, and data voltages are applied to the data lines 34 and transmitted to the pixel electrodes 30 through the switching devices 38. Therefore, when the scan voltages are applied to the scan lines 32 to turn on the switching devices 38, the data voltages on the data lines 34 will charge the pixel electrodes 39 through the switch devices 38, thereby twisting the liquid crystal molecules. When the scan voltages on the scan lines 32 are removed to turn off the switching devices 38, the data lines 34 and the pixels 36 will disconnect, and the pixel electrodes 39 will remain charged. The scan lines 32 turn the switching devices 38 on and off repeatedly so that the pixel electrodes 39 can be repeatedly charged. Different data voltages cause different twisting angles and show different transmission rates. Hence, the LCD 30 displays various images. Please refer to FIG. 5 showing a timing diagram of pixel data values varying in accordance with frames. According to the present invention, when driving any pixel 36 of the LCD panel 30, the driving circuit 10 generates a plurality of pixel data used for driving the pixel in sequence. As shown in FIG. 5, GN, GN(2), GN+1, GN+1(2), GN+2, GN+2(2), GN+3, GN+3(2) are the pixel data generated in frame periods N, N+1, N+2, N+3. The driving circuit 10 generates two pieces of pixel data for each pixel 36 in every frame period. The driving circuit 10 drives the pixel to reach gray levels in the frame periods N, N+1, N+2, N+3 according to the values of the pixel data GN−GN+2(2). For instance, when the pixel data GN, GN(2) are generated, the source driver of the driving circuit 10 converts the pixel data GN, GN(2) into two corresponding data impulses and then applies them to the liquid crystal device 39 via the data line 32 in the frame period N in order to control the transmission rate of the liquid crystal device 39. Similarly, data impulses corresponding to the pixel data GN+1−GN+3(2) are applied respectively to corresponding pixel electrodes 39 every half a frame period. Same as the prior art, the larger the value of the pixel data is, the higher the voltage of the corresponding data impulse is, and the larger the gray level value is. Please refer to FIG. 6 showing a timing diagram of the transmission rate of the pixel 36 varying in accordance with the frames. As described above, the driving circuit 10 generates two pieces of pixel data in each frame period, and then the source driver 18 generates two corresponding data impulses according to the two pieces of pixel data and applies them to the pixel electrode 39 of the corresponding pixel 36 in order to control the transmission rate and gray level of the pixel electrode 39. As shown in FIG. 6, the driving circuit 10 changes the transmission rate of the pixel electrode 39 of a pixel 36 from T1 to T2 in the frame period N+1. The pixel electrode 39 is applied with two data impulses corresponding to the pixel data GN+1, GN+1(2) in the frame period N+1 at a time interval of half a frame period. As shown in FIG. 6, although the transmission rate of the pixel electrode 39 cannot reach T2 in the first half period n+2 of the frame period N+1, in the later half period n+3 of the frame period N+1, the pixel electrode 39 is applied with another data impulse, so that the transmission rate can reach T2 in the frame period N+1 as required. Therefore, blurring will not occur. In the present embodiment, the two pieces of pixel data of each pixel in every frame period are generated by the blur clear converter 14. Please refer to FIG. 7 showing a block diagram of the blur clear converter 14. The blur clear converter 14 includes a multiplier 40, a processing circuit 42, a first image memory 44, a second image memory 46, a first memory controller 48, and a second memory controller 50. The multiplier 40 is for doubling the frequency of the control signal C to generate a multiplied signal C2. The first image memory 44 is controlled by the first memory controller 48 to delay current pixel data Gm for a frame period to generate delayed pixel data Gm−1 according to the control signal C. The processing circuit 42 generates a plurality of overdriven pixel data GN according to the current pixel data Gm and the delayed pixel data Gm−1. The second image memory 46 stores the overdriven pixel data GN, and the second memory controller 50 controls the second image memory 46 to output two overdriven pixel data GN, GN(2) to each pixel 36 within a frame period according to the multiplied signal C2 in order to have the source driver 18 apply two data impulses to a specific pixel 36 within a frame period according to the two overdriven pixel data GN, GN(2). Please refer to FIG. 8 showing a block diagram of the blur clear converter 60 according to the second embodiment of the present invention. The blur clear converter 60 functions the same as the blur clear converter 14, which includes a multiplier 62, a first image memory 66, a second image memory 68, a third image memory 70, a memory controller 64, a processing circuit 74, and a comparing circuit 72. The multiplier 62 is for doubling the frequency of the control signal C to generate a multiplied signal C2. The first image memory 66 is for receiving and temporarily storing a plurality of pixel data G. The second image memory 68 delays the plurality of pixel data G for a frame period to generate delayed pixel data Gm−1. The third image memory 70 delays the pixel data Gm−1 for a frame period to generate delayed pixel data Gm−2. Thus the pixel data Gm−2 lags the pixel data Gm−1 for a frame period, and so does the pixel data Gm−1 with respect to the pixel data Gm. The memory controller 64 controls the second image memory 68 and the third image memory 70 to output two overdriven pixel data in each frame period according to the multiplied signal C2. The processing circuit 74 generates two pieces of overdriven pixel data GN1, GN−1(2) for each pixel 36 in every frame period according to the pixel data Gm−1, Gm−2. The comparing circuit 72 compares the pixel data Gm−1 with the pixel data Gm−2 to determine the values of the overdriven pixel data GN−1, GN−1(2). Please refer to FIG. 9 showing a timing diagram of original pixel data received by the blur clear converter 60 varying in accordance with the frames, and FIG. 10 showing a timing diagram of overdriven pixel data generated by the blur clear converter 60 varying in accordance with the frames. As shown in FIG. 9, the original pixel data received by the blur clear converter 60 in the frame periods N and N+1 are respectively Gm and Gm+1, with a difference Diff between each other. The blur clear converter 60 generates the two overdriven pixel data GN+1, GN+1(2) with a difference ΔG between each other according to the original pixel data Gm, Gm+1. The difference ΔG is determined by the comparing circuit 72 in FIG. 8 for driving the pixels 36 according to difference conditions. The difference ΔG is determined according to the difference Diff between the original pixel data Gm and Gm+1. For instance, when the difference Diff is less than a specific value, the comparing circuit 72 determines the difference ΔG as 0, that is equating the overdriven pixel data GN+1 to the overdriven pixel data GN+1(2). Or when the difference Diff is larger than a specific value, the comparing circuit 72 modulates the difference ΔG to drive the LCD panel 30 properly. In contrast to the prior art, the present invention discloses a driving circuit and relating driving method to generate two pieces of pixel data in each frame period for every pixel on an LCD panel and then to generate two data impulses according to the two pieces of pixel data and to apply them to each pixel within a frame period in order to change the transmission rate of a pixel electrode. Thus, each of the pixels of the LCD panel is applied of a plurality of data impulses within a frame period, so that liquid crystal molecules of the pixels can twist to reach a predetermined gray level within a frame period, and blurring will not occur. Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.

<SOH> BACKGROUND OF INVENTION <EOH>1. Field of the Invention The invention relates to a driving circuit of a liquid crystal display (LCD) panel and its related driving method, and more particularly, to a driving circuit for applying over two data impulses to a pixel electrode within one frame period, and its related driving method. 2. Description of the Prior Art A liquid crystal display (LCD) has advantages of lightweight, low power consumption, and low divergence and is applied to various portable equipment such as notebook computers and personal digital assistants (PDAs). In addition, LCD monitors and LCD televisions are gaining in popularity as a substitute for traditional cathode ray tube (CRT) monitors and televisions. However, an LCD does have some disadvantages. Because of the limitations of physical characteristics, the liquid crystal molecules need to be twisted and rearranged when changing input data, which can cause the images to be delayed. For satisfying the rapid switching requirements of multimedia equipment, improving the response speed of liquid crystal is desired. Generally when driving an LCD, a driving circuit receives a plurality of frame data and then generates corresponding data impulses, scan voltages, and timing signals, according to the frame data, in order to control pixel operation of the LCD. Each of the frame data includes data for refreshing all of the pixels within a frame period; thus each of the frame data can be regarded as including a plurality of pixel data, and each of the pixel data is for defining the gray level that a pixel is required to reach within a frame period. In the general standard, each pixel can switch among 256 (2 8 ) gray levels, thus each of the pixel data is 8 bits in length. Please refer to FIG. 1 showing a timing diagram of pixel data values varying in accordance with the frames. When driving a pixel, the driving circuit receives a plurality of pixel data used for driving the pixel in sequence. As shown in FIG. 1 , GN, GN+1, GN+2 are the pixel data received in frame periods N, N+1, N+2, and the driving circuit determines the gray level of the pixel in the frame periods N, N+1, N+2 according to the values of the pixel data GN, GN+1, GN+2. In general, the larger the value of the pixel data is, the larger the gray level is. The driving circuit generates a data impulse corresponding to a frame period according to the pixel data GN, GN+1, GN+2, and applies the pulse to a pixel electrode of the corresponding pixel to have the pixel be in the appropriate gray level as required within each frame period. Please refer to FIG. 2 showing a timing diagram of different transmission rates of a pixel, varying in accordance with the frames. Two curves C 1 , C 2 are measured when the driving circuit changes the transmission rate from T 1 to T 2 beginning at frame period N. The curve C 1 shows the transmission rate of a pixel not overdriven corresponding to the frames, and the curve C 2 shows the transmission rate of the pixel overdriven corresponding to the frames. The U.S. published application No. 2002/0050965 is one of the references of the conventional overdriving method. There is a time delay when charging liquid crystal molecules, so that they cannot twist at a predetermined angle at a predetermined transmission rate. As shown by the curve C 1 , in the case of not being overdriven, the transmission rate cannot reach a predetermined level in the frame period N but has to wait until the frame period N+2. Such a delay causes blurring. In order to improve that, some conventional LCD are overdriven, which means applying a higher or a lower data impulse to the pixel electrode to accelerate the reaction speed of the liquid crystal molecules, so that the pixel can reach the predetermined gray level in a predetermined frame period. As shown by the curve C 2 , in the case of being overdriven, although the reaction speed of the liquid crystal molecules is faster than in case of not being overdriven, the transmission rate has to wait until frame period N+1 to reach T 2 . Thus, the requirement of reaching T 2 in the frame period N still remains unsatisfied.

<SOH> SUMMARY OF INVENTION <EOH>It is therefore a primary objective of the claimed invention to provide a driving circuit of an LCD panel and its relating driving method to solve the problem mentioned above. Briefly, the present invention provides a method for driving an LCD panel. The LCD panel includes a plurality of scan lines, a plurality of data lines, and a plurality of pixels. Each pixel is connected to a corresponding scan line and a corresponding data line, and each pixel includes a liquid crystal device and a switching device connected to the corresponding scan line, the corresponding data line, and the liquid crystal device. The method includes receiving continuously a plurality of frame data, generating a plurality of data impulses for each pixel in every frame period according to the frame data and applying the data impulses to the liquid crystal device of one of the pixels within one frame period via the data line connected to the pixel in order to control the transmission rate of the liquid crystal device of the pixel. The present invention further provides a driving circuit for driving an LCD panel including a blur clear converter for receiving frame data every frame period, each frame data comprising a plurality of pixel data and each pixel data corresponding to a pixel, the blur clear converter delaying current frame data to generate delayed frame data and generating a plurality of overdriven pixel data in every frame period for each pixel; a source driver for generating a plurality of data impulses to each pixel according to the plurality of overdriven pixel data generated by the blur clear converter and applying the data impulses to the liquid crystal device of the pixel via the scan line connected to the pixel in order to control the transmission rate of the liquid crystal device; and a gate driver for applying a scan line voltage to the switch device of the pixel so that the data impulses can be applied to the liquid crystal device of the pixel. These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

20040108

20070410

20050519

57312.0

PATEL, NITIN

DRIVING CIRCUIT OF A LIQUID CRYSTAL DISPLAY PANEL AND RELATED DRIVING METHOD

SMALL

ACCEPTED

ACCEPTED

METHOD AND SYSTEM FOR CREATING, VIEWING, EDITING, AND SHARING OUTPUT FROM A DESIGN CHECKING SYSTEM

Existing text output from a design rule checker is put in appropriate input format, and automatically displayed as text within a design tool using existing design tool capabilities, such as highlighting, zooming, and drawing box-regions. A graphical display of the output of the rule checker includes the informative text. Design rule violations are listed in a manner in which they can be individually selected. The output is displayed on a unique software program layer within the design tool so as to not effect or make any permanent changes to the original design file. The layers can be safely deleted when no longer in use.

1. A method of using text from a design tool to display an output to a user, said method comprising: graphically displaying said output from said text of said design tool; graphically listing design rule violations; displaying said output as part of a software layer of said design tool such that no permanent changes are made to any original design file; generating and annotating a subset output file for use by other users; and generating software help functions allowing said user to gain information about design rule violations. 2. The method of claim 1 wherein said design tool is a design rule checking system. 3. The method of claim 1 wherein said text comprises text output from said design tool. 4. The method of claim 3 wherein said text output from said design tool comprises an input file for software implementing said method. 5. The method of claim 1 including individually selecting said design rule violations. 6. The method of claim 1 including representing said output as part of said software layer of said design tool, and deleting said output when no longer required. 7. The method of claim 6 including having said software layer presented in a pop-up window display. 8. The method of claim 7 wherein said pop-up window further includes information identifying said design rule violations, net name, component name, information relating to design rules. 9. The method of claim 8 wherein said pop-up window further comprises the identification of parameters being checked along with information as to said parameters' importance. 10. The method of claim 1 including drawing a bounding box around any of said design rule violations. 11. The method of claim 1 including loading and viewing said subset output file without running said design tool rule checker. 12. The method of claim 1 wherein said subset file includes saved information relating to an identified violation. 13. The method of claim 12 further including electronically sharing said saved information with different users. 14. The method of claim 12 comprising requesting said identified violation be saved such that a resulting output file contains only those of said design rule violations that a user requested be saved, preserving said original design file. 15. The method of claim 1 wherein said software help functions include highlighting, zooming, measuring cumulative distance between multiple points, changing viewpoints of a design, changing magnification level, changing feature visibility, and changing location of a viewport. 16. The method of claim 1 further comprising reselecting said design rule violations to return to an originally presented view. 17. A method of viewing violations identified by a design rule checker comprising: inputting text output from said design rule checker into a software program routine for viewing said violations; inputting design file information into said software program routine; generating a subset output file of said violations for a user to view; and editing said design file based on said violations. 18. The method of claim 17 further comprising: inputting design data and rule checker parameters into a design rule checking tool; and performing design rule checking. 19. The method of claim 17 including generating a subset text output file of said violations. 20. The method of claim 17 including allowing said user to individually select said violations. 21. The method of claim 17 including representing said output as part of a software layer of said design rule checker, and deleting said output when no longer required. 22. The method of claim 21 including having said software layer presented in a pop-up window display. 23. A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps for using text from a design tool to display an output to a user, said method steps comprising: graphically displaying said output from said text of said design tool; graphically listing design rule violations; displaying said output as part of a software layer of said design tool such that no permanent changes are made to any original design file; generating and annotating a subset output file for use by other users; and generating software help functions allowing said user to gain information about design rule violations. 24. The program storage device of claim 23 wherein said text comprises text output from said design tool. 25. The program storage device of claim 24 wherein said text output from said design tool comprises an input file for software implementing said method. 26. The program storage device of claim 23 including individually selecting said design rule violations. 27. The program storage device of claim 23 including representing said output as part of said software layer of said design tool, and deleting said output when no longer required. 28. The program storage device of claim 27 including having said software layer presented in a pop-up window display. 29. A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps for viewing violations identified by a design rule checker, said method steps comprising: inputting text output from said design rule checker into a software program routine for viewing said violations; inputting design file information into said software program routine; generating a subset output file of said violations for a user to view; and editing said design file based on said violations. 30. The method of claim 29 including generating a subset text output file of said violations.

BACKGROUND OF INVENTION This invention relates to the field of printed feature manufacturing, such as printed circuit boards and integrated circuitry manufacturing. In particular, this invention relates design tools for printed circuit board layouts and integrated device layouts. More specifically, the invention relates to graphically identifying each violation of a design rule to a user using the output of a design rule checker. Computer aided design (CAD) software programs are used to create design drawings such as electrical schematics. To fabricate either a printed circuit board or an integrated circuit (IC), engineers first use a logical electronic design automation (EDA) tool, to create a schematic design, such as a schematic circuit design or layout. The layout typically contains data layers that correspond to the actual layers to be fabricated in the circuit board or circuit. Such designs usually have to adhere to a set of predefined criteria, referred to as design rules, which are unique to the product, product type, or manufacturing process. Various techniques have been developed to ensure conformance to design rules. These techniques include the use of design rule checking programs run subsequent to the design creation and the use of interactive design rule checking procedures run continually during the design process. Once the layout is created, the layout is verified to ensure that the layout has been properly executed and that the final layout created adheres to certain geometric design rules. These layout verifications are called design rule checks. Such tools are available from CADENCE DESIGN SYSTEMS and from MENTOR GRAPHICS. In these tools a number of physical design rule checkers exist. These rule checkers compare actual design data against a user or default-specified set of design parameters and output any non-complying features as violations. When anomalies or errors are discovered by these checking tools, the designer must repair the fault before the layout is sent out for circuit manufacturing and wafer fabrication. Design rule checking searches the design for violations of a predetermined set of conditions, for example, minimum line widths and minimum separations, and returns a result indicating whether design rule violations were found. The intermediate layer(s) associated with a design rule checker can store a list of design rule errors found, or a modified design that satisfies the design rules. The design rule checker is typically a software program or module, which is provided by an established vendor or specially programmed. The design rule checker is adapted to receive a digital representation of the layout pattern to be analyzed. Such representations specify in a standard format the coordinates of defined edges on a pattern or other geometric features. Generally, the layout design is provided in a digital form to a design rule checker set to select only those features that violate the design rules. In U.S. Pat. No. 6,282,696 issued to Garza, et al., on Aug. 28, 2001, entitled “PERFORMING OPTICAL PROXIMITY CORRECTION WITH THE AID OF DESIGN RULE CHECKERS,” a design rule checker is used to locate features of an integrated circuit layout design meeting predefined criteria. A partial layout is created as a new file having coordinates for each small feature under consideration. However, graphical assistance in dealing with violations identified by the design rule checker is neither taught nor suggested. One problem with these design rule checkers is that a majority of them output the violations as a text file. Reviewing the output of these design rule checkers requires significant time on the part of the user to locate and understand the violation by using the text output to manually interact with the design file. A few design rule checkers also output some graphical information, but in most cases this information is limited to a pointer that identifies a problem location without providing data related to any specifics about the violation. An example of this type of output is demonstrated by the CADENCE ALLEGRO™ DRC (design rule checker). In these types of systems, the location of the violation is given, but useful information concerning the violation remains unknown to the user. In U.S. Pat. No. 6,415,421 issued to Anderson, et al., on Jul. 2, 2002, entitled “INTEGRATED VERIFICATION AND MANUFACTURABILITY TOOL,” a hierarchical database is taught to store shared design data accessed by multiple verification tool components, such as design rule check. The database includes representations of one or more additional, or intermediate layer structures that are created and used by the verification tool components for operations performed on the design being verified. Once again, however, graphical representations of violations are not suggested or taught. Generally, the output of design rule checkers is a one-time-only output, either in a text file or in a view of the design file within the design environment. There are no utilities within the violation review process for a user to create a desired subset of those violations that could then be shared with a designer. The user is typically forced to manually edit the original text output and give the resulting list to the designer, who must repeat the process of manually locating and understanding the violations. Often, when reviewing a list of violations, the user needs to obtain more information about a particular violation, such as inquiring about the neighboring features or some of the properties associated with the violating feature. With traditional violation reviewing, the user enters a number of keystrokes to get this information. If in the process of obtaining this information, the view of the design changes significantly, such as scrolling to a different location within the design, manual effort is required to relocate the violation in question. Consequently, there is a need in the art to take the output of a design rule checker and graphically identify each violation to the user using design tool operations. Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a graphical method for viewing and editing output from a design rule checking system. It is another object of the present invention to provide a system and method that takes a text file from a design rule checker and graphical displays violations to a user. A further object of the invention is to provide an interactive graphic tool using the output of a design rule checker to allow multiple users to view output without re-running the rule checking software. It is yet another object of the present invention to provide a non-destructive interactive graphical tool to allow a designer to work with design rule checking output without risking existing data. Another object of the present invention is to allow a user to view a design violation from any rule-checking tool that outputs in compatible format. Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification. SUMMARY OF INVENTION The above and other objects, which will be apparent to those skilled in art, are achieved in the present invention which is directed to a method of using text from a design tool to display an output to a user, the method comprising: graphically displaying the output from the text of the design tool; graphically listing design rule violations; displaying the output as part of a software layer of the design tool such that no permanent changes are made to any original design file; generating and annotating a subset output file for use by other users; and generating software help functions allowing the user to gain information about design rule violations. The design tool may be a design rule checking system. The text comprises text output from the design tool. The text output from the design tool comprises an input file for software implementing the method. The method further includes individually selecting the design rule violations. The output may be represented as part of the software layer of the design tool and deleted when no longer required. The software layer may be presented in a pop-up window display. The pop-up window includes information identifying the design rule violations, net name, component name, information relating to design rules. The pop-up window further comprises the identification of parameters being checked along with information as to the parameters' importance. The method may include drawing a bounding box around any of the design rule violations. The subset output file may be loaded and viewed without running the design tool rule checker. The subset file may include saved information relating to an identified violation. The saved information may be shared electronically with different users. The identified violation may be requested by the user to be saved such that a resulting output file contains only those of the design rule violations that the user requested be saved, preserving the original design file. Software help functions may include highlighting, zooming, measuring cumulative distance between multiple points, changing viewpoints of a design, changing magnification level, changing feature visibility, and changing location of a viewport. The design rule violations may be reselected to return to an originally presented view. In a second aspect, the present invention is directed to a method of viewing violations identified by a design rule checker comprising: inputting text output from the design rule checker into a software program routine for viewing the violations; inputting design file information into the software program routine; generating a subset output file of the violations for a user to view; and editing the design file based on the violations. The method may further comprise: inputting design data and rule checker parameters into a design rule checking tool; and performing design rule checking. The method includes generating a subset text output file of the violations and allowing the user to individually select the violations. The output may be represented as part of a software layer of the design rule checker, and deleted when no longer required. The software layer may be presented in a pop-up window display. In a third aspect, the present invention is directed to a program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps for using text from a design tool to display an output to a user, the method steps comprising: graphically displaying the output from the text of the design tool; graphically listing design rule violations; displaying the output as part of a software layer of the design tool such that no permanent changes are made to any original design file; generating and annotating a subset output file for use by other users; and generating software help functions allowing the user to gain information about design rule violations. The text comprises text output from the design tool. The text output from the design tool comprises an input file for software implementing the method. The design rule violations may be individually selected. In a fourth aspect, the present invention is directed to a program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps for viewing violations identified by a design rule checker, the method steps comprising: inputting text output from the design rule checker into a software program routine for viewing the violations; inputting design file information into the software program routine; generating a subset output file of the violations for a user to view; and editing the design file based on the violations. BRIEF DESCRIPTION OF DRAWINGS The features of the invention believed to be novel and the elements characteristic of the invention are set forth with particularity in the appended claims. The figures are for illustration purposes only and are not drawn to scale. The invention itself, however, both as to organization and method of operation, may best be understood by reference to the detailed description which follows taken in conjunction with the accompanying drawings in which: FIG. 1 depicts the overall process flow for the present invention. FIG. 2 depicts a pop-up window of violations to view and available to be chosen by the user. FIG. 3 depicts the pop-up window of FIG. 2 with a sample violation viewing along with a highlighted feature pertinent to the violation. FIG. 4 depicts the pop-up window of FIG. 2 with general highlighting and boxing of first and second violation features. FIG. 5 depicts the pop-up window of FIG. 2 with a bounding box around a region pertinent to the violation. FIG. 6 depicts the pop-up window of FIG. 2 having a box drawn to show a feature search region. FIG. 7 depicts a portion of the pop-up window of FIG. 2 showing basic helper function soft-keys, including a “save line” feature. FIG. 8 depicts an additional helper function pop-up window with examples of helper function available to the user. FIG. 9 depicts a sample viewing of the selection of a subset output file from the directory. FIG. 10 depicts a sample violation pop-up window list showing the subset of the overall list specified by the user to communicate with the designer. FIG. 11 depicts sample instructions for the Cadence Allegro design tool advising the user of the temporary layer created for viewing violations. FIG. 12 depicts an example of a temporary layer created for viewing violations within the CADENCE ALLEGRO design environment that can be safely removed without making permanent, destructive changes to the original design. FIG. 13 depicts an example of helper function that has a bounding box as its input. FIG. 14 depicts a second example of a helper function where the user may select a function that has a feature name as its input. DETAILED DESCRIPTION In describing the preferred embodiment of the present invention, reference will be made herein to FIGS. 1-14 of the drawings in which like numerals refer to like features of the invention. The present invention takes existing text output from a rule checker in appropriate input format, and automatically displays the text within the design tool using existing design tool capabilities, such as highlighting, zooming, drawing box-regions, and the like. Information is graphically associated with the rule checker text output. A graphical user interface output of the rule checker is then provided. The invention graphically displays the output of the rule checker including the informative text. Any violations are listed in a manner in which they can be individually selected. The output is displayed on a unique layer within the design tool so as to make no permanent changes to the original design file. The layers may be safely deleted when no longer in use. This process provides a user with means to annotate and output a subset file for use by other users and designers. For example, a designer may then load and view a subset file using the present invention, without having to run the rule checker. Useful helper functions are also provided, which allow the user or designer to gain more information about the design. These functions are generally available in the design tool; however, their implementation would normally involve a more intensive manual process. Importantly, the present invention takes the output of the design rule checker and graphically identifies each violation to the user using design tool operations. The user selects from a list of violations, which may be presented in a pop-up window, and zooms the view to an appropriate level for the user to clearly see the violation, depending on the type of information contained in the rule checker file. This process highlights and effectively draws a bounding box around any violation in question if applicable. The pop-up window is made to contain information identifying the violation along with other pertinent information about it, such as the net name, component name, and the like, which will aid the user in understanding more about the violation. The pop-up window also contains information about the checked design rule, which helps the user to understand the violation. This information includes identifying the parameters being checked and information as to why these parameters are important. Importantly, the output file of the design rule checker must be in a format that can communicate with, and be processed by, the present invention. The output file of the design rule checker is the input file for the Invention. The user applies the rule checker text output to speed up and simplify the review of the design rule checker output. The present invention generates an output file that allows the user to save information related to identified violations in order to share the information with a designer or other user. In this process, the user requests that a particular violation be saved. The resulting output file contains only those violations that the user requested to be saved. A new user reviewing this subset file can then view precisely what the first user experienced. The original file is preserved. Consequently, the creation of this subset file is repeatable for multiple, unique output files. Normally, extensive user interaction is necessary to obtain additional information about the violating feature or surrounding features. This interaction generally requires a substantial number of keystrokes, which need to be frequently repeated. The process of getting this additional information may, on occasion, cause the user to change the viewpoint of the design, either the magnification level, feature visibility, or location of the view port. The present invention affords multiple advantages here. First, “helper functions” are automatically integrated for common activities, such as zooming to a region, measuring cumulative distance between multiple points, resetting visibility, and the like. This integration saves input time and removes input mistakes by reducing the number of keystrokes necessary for input. Second, since a list of the violations is contained within a selectable popup window, the user need only reselect the violation to return to the originally presented view. The issues addressed by the present invention enable a user to save significant time. Typically, timesavings can be upward of 75-90% of the original, manual review time. Overall Process Flow FIG. 1 depicts the overall process flow for the present invention. The invention input file 6 is a software tool that provides a graphical user representation for a printed circuit board design file 1 and the output of a design rule checker 4. The overall application of the invention is typically as follows: The user applies rule checker parameters 3 against a design file or some subset of the design file data 2 within a design rule checker 4. The rule checker 4 compares the design data 1, 2 against the rule checker parameters 3 and provides output to the user in text form 5 and in a standard file format specified for the input file 6. The present invention then a “violation viewer” methodology 8 that generates an output file 9 allowing the user to save information related to identified violations. This includes the data from the design file 1, and uses the input file 6 to graphically identify the rule checker output to the user. When the user identifies particular violations that need to be shared with the designer, a portion of the “violation viewer” methodology 8 is used to create a subset output file 9 that contains only that violation information to be shared with the designer. If appropriate, a text version of this output 7 may also be generated. The designer operates the “violation viewer” methodology 8 similar to the original user, applying the subset output file 9 against the design file 1, using the text output 7 as an additional reference if needed. The designer identifies and performs necessary design file changes 10 on the design file 1. This process may then iterate through from the rule checking process as many times as is deemed necessary by the user. Upon initializing the software to perform the methodology of the present invention, the user is presented with a pop-up window 11 as shown in FIG. 2, which lists the violations reported 12 along with some descriptive text 13 taken from the rule checker to identify the rule check performed. If the list 12 is longer than the window permits, a scroll bar 17 is provided to scroll through the list 12. The user may select a violation to be displayed, which will then be highlighted 1) either by selecting it with the mouse pointer, using the “up” and “down” arrow keys on the keyboard, or with the Prev(ious) 18 and Next 19 clickable software buttons. For each violation, useful information such as an identifier number 15 and violation description 16 is shown in the list 12 as provided by the rule checker output 6. The graphical representation of the rule checker output 6 can be shown to the user in a variety of ways. The software for the present invention is designed to interact with the design file software using the design file software's various capabilities. A feature central to the violation 25 may be highlighted as depicted in FIG. 3. Where a violation contains a main description 16 and a secondary feature related to the violation 23, both highlighting of the main feature 25 and highlighting and/or the drawing of a small box around the secondary feature 24 can be performed. This is shown in FIG. 4. If a bounding region is pertinent to the violation, a bounding box of prescribed distance may be drawn around the key feature 26. FIG. 5 depicts a bounding box around the region. In this example, a box is drawn around a component pin at a distance from all sides of the pin. If the violation relates to the lack of a desired feature that should be located within a region, a bounding box representing the checked region may be drawn 28, as depicted in FIG. 6. The box is drawn to indicate a feature search region based on a set of grid coordinates specified by the rule checker. The box drawn 28 represents one grid box in the overall grid. In addition to these graphical representation capabilities, the invention methodology also provides the user with the ability to output a subset list of the violations that need further communication 7, 9. This output file is created with the “save line” software button 21 on the main pop-up window 11 as shown in FIG. 7. Once created, the subset output 9 may be viewed graphically within the design tool. The user accesses this ability primarily through an additional helper function pop-up window 38 shown in FIG. 8. The helper functions include an initial set “Goto Point”, “Get Distance”, and “Reset Find Filter”, and additional helper functions including “Start Vioviewer”, “Outline ON/OFF”, “Show Comp”, “Show Comp Info”, “Show Decaps”, “Show Pin”, “Show Net”, “Show Net Info”, “Show Seg”, “Get Layer Thick”, “Sublayer Thick”, and “Done”. The “Goto Point” allows the user to input an x- and y-coordinate and zooms such that the selected coordinate is at the screen's center. The “Get Distance” allows the user to select two points on the screen, returning the distance between the selected two points. The “Reset Find Filter” resets the state of the selection feature. The “Outline On/Off” toggles the design element called “outline” to an on or off state. The “Show Comp” allows the user to input a component identifier, and zooms the display such that the component is at the center of the screen and highlighted. The “Show Comp Info” allows the user to input a component identifier, and returns a pop-up window containing the component properties. The “Show Decaps” highlights decoupling capacitors connected to the net specified by the user. The “Show Pin” takes the user input of a component pin, and zooms so that the pin is in the center of the screen and highlighted. “Show Net” takes the user input of a net, and zooms so that the net is in the center of the screen and highlighted. “Show Net Info” allows the user to input a net identifier, and returns a pop-up window containing the net properties. “Show Seg” takes the user input of a net segment, and zooms so that the net segment is in the center of the screen and highlighted. “Get Layer Thick” allows the user to select a layer identifier and returns the thickness dimension from the design data. “Sublayer Thick” allows the user to select a sublayer identifier and returns the thickness dimension from the design data. “Done” closes the helper window. Along with an initial set of helper functions 29, a soft-key button “Start Vioviewer” 31 is programmed to start the viewing of the input files 6, 9. When this button is selected, a violation file selector pop-up window 30 is presented as seen in FIG. 9. This window shows a list of files 33 that may be selected. The subset files are created as separate files from the original input files. When the desired file is identified, it may be selected by clicking on it, which initiates loading it into the file path box 34. Alternatively, if the user knows the specific file path, he or she may type it directly into the file path box 34. Referring to FIG. 10, once started, the present invention operates on the subset file 9 and shows a similar pop-up box 110 to the violation list as shown previously. In this case, the violation list 120 contains only those in the subset output file 9. This can be seen in the violation list 120. FIG. 10 depicts the sample violation pop-up window list showing the subset of the overall list specified by a user to communicate with a designer. Since the invention relies on interacting with the design file 1 within the design tool, the features 24, 25, 26, 27 shown in FIGS. 2-6 are created as design elements in the design file 1. In order to keep these design elements 24, 25, 26, 27 from permanently altering the original design file 1, they are created on a unique layer or class 37 within the design file 1, and can be deleted from the design file 1 without permanently altering the original data. Instructions 35, 36 for removal of this layer or class 37 may be provided to the user through interaction with the design tool. FIG. 11 depicts sample instructions for the CADENCE ALLEGRO™ design tool, advising the user of the temporary layer created for viewing violations that can be safely removed without making permanent, destructive changes to the original design. An example of this layer or class 37 within the CADENCE ALLEGRO design environment is shown in FIG. 12. The layer in this example is labeled “VioView” 370. FIG. 8 showed an example of a number of helper functions 29 available via a pop-up window 28 within the invention. An example of another helper function 290 is shown in FIG. 13. In this figure, the user has selected a helper function 290 that has a bounding box as its input. A pop-up window 380 enables the user to specify the coordinates of a rectangular box 390 that the invention can draw a bounding box about and zoom in magnification. FIG. 14 is a second example of a helper function 290a where the user may select a function that has a feature name as its input. This selection displays a pop-up box 400 in which the user specifies a feature name 410. Typical operation of this helper function 290 would highlight the feature and zoom the magnification to an appropriate level. ALTERNATIVE EMBODIMENTS The description of the present invention has thus far been based on using the invention to graphically display design rule checker output that is overlaid onto the design file within the design tool environment. Alternately, the invention may be used to output a format that is viewable in a different software program or in a common graphics format such as, but not limited to, JPEG, GIF, TIFF, BMP, HTML, and the like. The above-identified figures are examples of the invention as used with the Cadence Allegro design tool. However, the invention is not limited to one tool as long as design tool commands are driven by a software program, the invention can be used in any design tool. Through the use of a translator from one format set of instructions to another, the subset file or even the original design rule checker file can be translated to work with a design tool other than the one originally used to create the design. While the present invention has been particularly described, in conjunction with a specific preferred embodiment, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. It is therefore contemplated that the appended claims will embrace any such alternatives, modifications and variations as falling within the true scope and spirit of the present invention.

<SOH> BACKGROUND OF INVENTION <EOH>This invention relates to the field of printed feature manufacturing, such as printed circuit boards and integrated circuitry manufacturing. In particular, this invention relates design tools for printed circuit board layouts and integrated device layouts. More specifically, the invention relates to graphically identifying each violation of a design rule to a user using the output of a design rule checker. Computer aided design (CAD) software programs are used to create design drawings such as electrical schematics. To fabricate either a printed circuit board or an integrated circuit (IC), engineers first use a logical electronic design automation (EDA) tool, to create a schematic design, such as a schematic circuit design or layout. The layout typically contains data layers that correspond to the actual layers to be fabricated in the circuit board or circuit. Such designs usually have to adhere to a set of predefined criteria, referred to as design rules, which are unique to the product, product type, or manufacturing process. Various techniques have been developed to ensure conformance to design rules. These techniques include the use of design rule checking programs run subsequent to the design creation and the use of interactive design rule checking procedures run continually during the design process. Once the layout is created, the layout is verified to ensure that the layout has been properly executed and that the final layout created adheres to certain geometric design rules. These layout verifications are called design rule checks. Such tools are available from CADENCE DESIGN SYSTEMS and from MENTOR GRAPHICS. In these tools a number of physical design rule checkers exist. These rule checkers compare actual design data against a user or default-specified set of design parameters and output any non-complying features as violations. When anomalies or errors are discovered by these checking tools, the designer must repair the fault before the layout is sent out for circuit manufacturing and wafer fabrication. Design rule checking searches the design for violations of a predetermined set of conditions, for example, minimum line widths and minimum separations, and returns a result indicating whether design rule violations were found. The intermediate layer(s) associated with a design rule checker can store a list of design rule errors found, or a modified design that satisfies the design rules. The design rule checker is typically a software program or module, which is provided by an established vendor or specially programmed. The design rule checker is adapted to receive a digital representation of the layout pattern to be analyzed. Such representations specify in a standard format the coordinates of defined edges on a pattern or other geometric features. Generally, the layout design is provided in a digital form to a design rule checker set to select only those features that violate the design rules. In U.S. Pat. No. 6,282,696 issued to Garza, et al., on Aug. 28, 2001, entitled “PERFORMING OPTICAL PROXIMITY CORRECTION WITH THE AID OF DESIGN RULE CHECKERS,” a design rule checker is used to locate features of an integrated circuit layout design meeting predefined criteria. A partial layout is created as a new file having coordinates for each small feature under consideration. However, graphical assistance in dealing with violations identified by the design rule checker is neither taught nor suggested. One problem with these design rule checkers is that a majority of them output the violations as a text file. Reviewing the output of these design rule checkers requires significant time on the part of the user to locate and understand the violation by using the text output to manually interact with the design file. A few design rule checkers also output some graphical information, but in most cases this information is limited to a pointer that identifies a problem location without providing data related to any specifics about the violation. An example of this type of output is demonstrated by the CADENCE ALLEGRO™ DRC (design rule checker). In these types of systems, the location of the violation is given, but useful information concerning the violation remains unknown to the user. In U.S. Pat. No. 6,415,421 issued to Anderson, et al., on Jul. 2, 2002, entitled “INTEGRATED VERIFICATION AND MANUFACTURABILITY TOOL,” a hierarchical database is taught to store shared design data accessed by multiple verification tool components, such as design rule check. The database includes representations of one or more additional, or intermediate layer structures that are created and used by the verification tool components for operations performed on the design being verified. Once again, however, graphical representations of violations are not suggested or taught. Generally, the output of design rule checkers is a one-time-only output, either in a text file or in a view of the design file within the design environment. There are no utilities within the violation review process for a user to create a desired subset of those violations that could then be shared with a designer. The user is typically forced to manually edit the original text output and give the resulting list to the designer, who must repeat the process of manually locating and understanding the violations. Often, when reviewing a list of violations, the user needs to obtain more information about a particular violation, such as inquiring about the neighboring features or some of the properties associated with the violating feature. With traditional violation reviewing, the user enters a number of keystrokes to get this information. If in the process of obtaining this information, the view of the design changes significantly, such as scrolling to a different location within the design, manual effort is required to relocate the violation in question. Consequently, there is a need in the art to take the output of a design rule checker and graphically identify each violation to the user using design tool operations. Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a graphical method for viewing and editing output from a design rule checking system. It is another object of the present invention to provide a system and method that takes a text file from a design rule checker and graphical displays violations to a user. A further object of the invention is to provide an interactive graphic tool using the output of a design rule checker to allow multiple users to view output without re-running the rule checking software. It is yet another object of the present invention to provide a non-destructive interactive graphical tool to allow a designer to work with design rule checking output without risking existing data. Another object of the present invention is to allow a user to view a design violation from any rule-checking tool that outputs in compatible format. Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.

<SOH> SUMMARY OF INVENTION <EOH>The above and other objects, which will be apparent to those skilled in art, are achieved in the present invention which is directed to a method of using text from a design tool to display an output to a user, the method comprising: graphically displaying the output from the text of the design tool; graphically listing design rule violations; displaying the output as part of a software layer of the design tool such that no permanent changes are made to any original design file; generating and annotating a subset output file for use by other users; and generating software help functions allowing the user to gain information about design rule violations. The design tool may be a design rule checking system. The text comprises text output from the design tool. The text output from the design tool comprises an input file for software implementing the method. The method further includes individually selecting the design rule violations. The output may be represented as part of the software layer of the design tool and deleted when no longer required. The software layer may be presented in a pop-up window display. The pop-up window includes information identifying the design rule violations, net name, component name, information relating to design rules. The pop-up window further comprises the identification of parameters being checked along with information as to the parameters' importance. The method may include drawing a bounding box around any of the design rule violations. The subset output file may be loaded and viewed without running the design tool rule checker. The subset file may include saved information relating to an identified violation. The saved information may be shared electronically with different users. The identified violation may be requested by the user to be saved such that a resulting output file contains only those of the design rule violations that the user requested be saved, preserving the original design file. Software help functions may include highlighting, zooming, measuring cumulative distance between multiple points, changing viewpoints of a design, changing magnification level, changing feature visibility, and changing location of a viewport. The design rule violations may be reselected to return to an originally presented view. In a second aspect, the present invention is directed to a method of viewing violations identified by a design rule checker comprising: inputting text output from the design rule checker into a software program routine for viewing the violations; inputting design file information into the software program routine; generating a subset output file of the violations for a user to view; and editing the design file based on the violations. The method may further comprise: inputting design data and rule checker parameters into a design rule checking tool; and performing design rule checking. The method includes generating a subset text output file of the violations and allowing the user to individually select the violations. The output may be represented as part of a software layer of the design rule checker, and deleted when no longer required. The software layer may be presented in a pop-up window display. In a third aspect, the present invention is directed to a program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps for using text from a design tool to display an output to a user, the method steps comprising: graphically displaying the output from the text of the design tool; graphically listing design rule violations; displaying the output as part of a software layer of the design tool such that no permanent changes are made to any original design file; generating and annotating a subset output file for use by other users; and generating software help functions allowing the user to gain information about design rule violations. The text comprises text output from the design tool. The text output from the design tool comprises an input file for software implementing the method. The design rule violations may be individually selected. In a fourth aspect, the present invention is directed to a program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps for viewing violations identified by a design rule checker, the method steps comprising: inputting text output from the design rule checker into a software program routine for viewing the violations; inputting design file information into the software program routine; generating a subset output file of the violations for a user to view; and editing the design file based on the violations.

20040112

20080101

20050714

64330.0

SIEK, VUTHE

METHOD AND SYSTEM FOR CREATING, VIEWING, EDITING, AND SHARING OUTPUT FROM A DESIGN CHECKING SYSTEM

UNDISCOUNTED

ACCEPTED

ACCEPTED

FLAP-TYPE ROTARY FINISHING DEVICE

A rotary finishing device including a generally circular hub having an inner periphery and an outer periphery. The outer periphery includes a plurality of slots formed thereabout, which are defined by a pair of side portions. The plurality of slots are generally uniformly spaced about the outer periphery of the hub. Each of the slots has at least one finishing sheet secured therein by an adhesive.

1. A rotary finishing device, comprising: a generally circular hub having an inner periphery and an outer periphery, said inner periphery defining a throughhole: a plurality of slots formed about said outer periphery of said generally circular hub, each of said plurality of slots being defined by a pair of side portions extending from said outer periphery, said plurality of slots being generally uniformly spaced around said generally circular hub; and at least one of said plurality of slots having at least one finishing sheet secured therein by an adhesive; at least one serration formed in each of said plurality of slots to assist in adhering said at least one finishing sheet to said hub. 2. The rotary finishing device of claim 1, wherein said generally cylindrical hub is formed of a metal material. 3. The rotary finishing device of claim 2, wherein said generally cylindrical hub is constructed of aluminum. 4. The rotary finishing device of claim 1, wherein said generally cylindrical hub is formed by an extrusion process. 5. The rotary finishing device of claim 1, wherein said pair of side portions extends generally outward from said outer periphery. 6. The rotary finishing device of claim 1, wherein said pair of side portions extends generally inward from said outer periphery. 7. The rotary finishing device of claim 1, wherein said generally circular hub includes a centerline defining a reference axis that extends from said centerline to a point between said side portions and wherein said pair of side portions extend from said outer periphery in a direction generally parallel to said reference axis. 8. The rotary finishing device of claim 1, wherein said generally circular hub includes a centerline defining a reference axis that extends from said centerline to a point between said side portions and wherein said pair of side portions extend from said outer periphery in a direction parallel to said reference axis. 9. The rotary finishing device of claim 1 wherein said pair of side portions extends from said outer periphery such that each of said plurality of slots is generally rounded. 10. The rotary finishing device of claim 1, wherein said adhesive secures said at least one finishing sheet within said slot by adhering it to each of said pair of side portions. 11. The rotary finishing device of claim 1, further comprising; an end cap in communication with said generally cylindrical hub such that a portion of said end cap is in communication with said generally cylindrical hub to effectuate driving thereof. 12. (canceled) 13. The rotary finishing device of claim 1, wherein each of said plurality of slots includes at least one finishing sheet secured therein by an adhesive. 14. The rotary finishing device of claim 13, wherein each of said plurality of slots includes at least one sheet of sandpaper secured therein by an adhesive. 15. A rotary finishing device comprising: a generally circular metal hub having an inner periphery and an outer periphery; at least one end cap in releasable communication with said inner periphery of said generally circular hub to allow driving thereof about an axis of rotation; a plurality of slots uniformly spaced about said outer periphery of said generally circular hub; and at least one sheet of a finishing media secured by an adhesive within at least two of said plurality of slots, said finishing media being disposed substantially along the entirely of at least one side of said at least one sheet. 16. The rotary finishing device of claim 15, wherein each of said at least two slots is defined by a pair of side portions. 17. The rotary finishing device of claim 16, wherein said pair of side portions of each of said at least two slots are oriented generally parallel to each other. 18. The rotary finishing device of claim 16, wherein each of said pair of side portions extend from said outer periphery in a generally parallel direction to a reference line extending from said axis of rotation to a point between said side portions. 19. The rotary finishing device of claim 16, wherein said pair of side portions extend from said outer periphery In a non-parallel direction to a reference line extending from said axis of rotation to a point between said side portions. 20. The rotary abrasive device of claim 15, wherein at least one of said plurality of slots includes at least one serration formed therein to provide increased adhering power to said adhesive. 21. The rotary abrasive device of claim 20, wherein said adhesive is an epoxy. 22. (canceled) 23. The rotary abrasive device of claim 15, wherein said generally cylindrical hub is constructed of aluminum. 24. The rotary abrasive device of claim 15, wherein said generally cylindrical hub is formed by an extrusion process. 25. A rotary finishing device, comprising: a generally circular hub having a centerline, an outer periphery, and an inner periphery defining a throughhole; a plurality of slots spaced about said outer periphery of said generally circular hub, said plurality of slots positioned at approximately an equal number of degrees apart from one another; at least one of said plurality of slots being defined by a pair of side portions that extend from said outer periphery of said generally circular hub in a direction not parallel to a reference line extending from said centerline to a point between said pair of side portions, said pair of side portions being generally parallel to one another; and at least one sheet of a finishing media secured by an epoxy within said at least one slot, said finishing media being disposed substantially along an entirety of at least one side of said at least one sheet. 26. The rotary finishing device of claim 25, said generally cylindrical hub is formed of a metal material. 27. The rotary finishing device of claim 26, wherein said generally cylindrical hub is constructed of aluminum. 28. The rotary finishing device of claim 25, wherein said generally cylindrical hub is formed by an extrusion process. 29. The rotary finishing device of claim 25, wherein said epoxy secures said finishing media within each of said slots by adhering them to said outer periphery and at least a portion of each of said pair of side portions. 30. The rotary finishing device of claim 25, wherein said finishing media consists of at least one sheet of sandpaper. 31. The rotary finishing device of claim 25, further comprising: an end cap in communication with said generally cylindrical hub such that a portion of said end cap contacts said generally cylindrical hub. 32. The rotary finishing device of claim 25, wherein said outer periphery includes at least one serration formed in said at least one slot to assist in adhering said finishing media to said generally circular hub. 33-34. (canceled) 35. The rotary finishing device of claim 25, wherein each of said pair of end portions extends generally outward from said outer periphery of said generally circular hub. 36. The rotary finishing device of claim 25, wherein each of said pair of end portions extends generally inward from said outer periphery of said generally circular hub. 37. A rotary finishing device, comprising: a generally circular hub having an inner periphery and an outer periphery, said inner periphery defining a throughhole; an end cap that is intended to engage said inner periphery of said generally circular hub; a plurality of slots spaced about said outer periphery of said generally circular hub, said plurality of slots defined by a pair of side portions and wherein said plurality of slots are spaced generally uniformly about said outer periphery of said generally circular hub, said side portions extend generally outwardly from said outer periphery and are oriented generally parallel to one another; and at least one sheet of a finishing media secured by an epoxy within at least two of said plurality of slots, said finishing media being disposed substantially along an entirety of at least one side of said at least one sheet. 38. The rotary finishing device of claim 37, wherein said generally cylindrical hub is formed of a metal material. 39. The rotary finishing device of claim 38, wherein said generally cylindrical hub is constructed of aluminum. 40. The rotary finishing device of claim 37, wherein said generally cylindrical hub is formed by an extrusion process. 41-43. (canceled) 44. The rotary finishing device of claim 41, wherein said generally circular hub includes a centerline defining a reference line that extends from said centerline to a point between said side portions wherein said pair of side portions extend from said outer periphery in a direction generally parallel to said reference line. 45. The rotary finishing device of claim 41, wherein said generally circular hub includes a centerline defining a line that extends from said centerline to a point between said side portions and wherein said pair of side portions extend from said outerperiphery in a direction not parallel to said reference line. 46. (canceled) 47. The rotary finishing device of claim 41, wherein said adhesive secures said at least one finishing sheet within said slot by adhering it to each of said pair of side portions.

BACKGROUND OF INVENTION The present invention relates generally to a rotary finishing device, and more particularly to a flap-type rotary finishing device having an epoxy attachment of the finishing media to a hub of the flap wheel. Rotary finishing tools are well known and typically include pieces or strips of a finishing medium. Such tools have proven to be very effective in the finishing of a wide variety of components such as those made from metal or the like. An exemplary rotary finishing tool utilizes generally rectangular pieces of abrasive paper, such as sandpaper, to provide a rotary abrasive device. One of the more common rotary finishing tools or devices is known in the art as a flap wheel. These flap wheels typically have annular arrays of flexible finishing strips and are commonly used in the finishing art. Most conventional rotary finishing devices consist of flexible strips each comprising sheets of material for finishing a surface of a piece. Many of these rotary finishing devices have abrasive particles bonded on one face thereof. Such rotary abrasive devices are useful for contoured polishing, cutting, or surface abrading of a variety of metal surfaces. Various fabrication methods for such a rotary device are known. One such conventional method requires that the finishing sheets have two notches in their opposite side edges near the base end of each strip. As the strips are arranged in an annular array, the notches form concentric circular depressions on opposite sides of the annular array. Suitable circular reinforcement mechanisms, such as two metallic end caps are mounted on opposite sides of the array. Each end cap has an inwardly extending lip, which engages the circular depressions to mechanically grip the inner ends of the finishing strips. This method thus relies on friction created between the two metallic end caps to maintain the base ends of the strips in contact with a hub of the rotary device. Although a rotary finishing device of this configuration performs suitably, its manufacture is rather expensive and requires two notches to be formed in each strip prior to assembly. The forming of these notches is both time consuming and costly. Further, the notches must be aligned properly with respect to each other to receive accurate placement of the metal end caps. Another known fabrication method for a rotary finishing device involves attaching the strips to an aluminum clip, such as by stapling. The metal clip with the attached strips is then loaded into a metal hub. A plurality of pins are then used to secure the hub to an end cap. These pins maintain the strips in communication with the metal hub, such that it is relatively difficult for the strips to become disengaged from the hub during polishing. However, these rotary devices are also relatively expensive and also require a relatively cumbersome assembly process. Yet another known fabrication process involves attaching the finishing media through the use of a suitable adhesive. This adhesive, such as an epoxy, is applied to the strips at their base ends to bond them to one another to form a unitary structure. The adhesive itself thus becomes the hub. Alternatively, a cardboard center is utilized to control the flow of adhesive. The cardboard center merely While these rotary devices are relatively inexpensive to produce, they are prone to breakage issues after high use. This breakage typically occurs due to failure of the epoxy, which is the weakest part of the device, as a result of the application of significant force during usage. When this breakage or failure of the rotary device occurs, a portion of the epoxy, together with the adhered strips, typically separates from the device. This results in an imbalanced rotary device, which requires replacement. Additionally, when the breakage occurs, because of the relatively high operating speeds of these devices, the separated portion can become a projectile, which can raise safety concerns or cause damage to the finishing device or surrounding apparatus. Therefore, a need exists for a rotary finishing device that is relatively inexpensive to manufacture, but has sufficient strength to withstand the high operating speeds to which these devices are subjected. SUMMARY OF INVENTION One advantage of the present invention is to provide a rotary finishing device that is less expensive than prior rotary finishing devices. Another advantage of the present invention is to provide a rotary finishing device that decreases the assembly time of the device without compromising its strength or integrity. Yet another advantage of the present invention is to provide a rotary finishing device that can be more inexpensively manufactured for a wide variety of different applications. A further advantage of the present invention is to provide a rotary finishing device that can be manufactured in a variety of different widths and lengths. In accordance with the above and the other advantages of the present invention, a rotary finishing device is provided. The rotary finishing device includes a generally circular hub having an inner periphery and an outer periphery. The inner periphery defines a passageway therethrough. The outer periphery of the hub has a plurality of slots extending therefrom. Each of the plurality of slots is defined by a pair of side portions. Additionally, the plurality of slots are generally uniformly spaced around the outer periphery. Each of the plurality of slots includes at least one finishing sheet secured therein. The at least one finishing sheet is secured within each of the plurality of slots by an adhesive. Other advantages of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims. BRIEF DESCRIPTION OF DRAWINGS For a more complete understanding of this invention, reference should now be made to the embodiments illustrated in greater detail in the accompanying drawings and described below by way of examples of the invention: FIG. 1 is a perspective view of a flap wheel, in accordance with one embodiment of the present invention; FIG. 2 is a front view of the flap wheel shown in FIG. 1; FIG. 3 is a front view of a generally cylindrical hub of the flap wheel shown in FIG. 1; FIG. 4 is a perspective view of a flap wheel in accordance with another embodiment of the present invention; FIG. 5 is a front view of the flap wheel shown in FIG. 4; FIG. 6 is a front view of a generally cylindrical hub of the flap wheel shown in FIG. 4; FIG. 7 is a perspective view of a flap wheel in accordance with yet another embodiment of the present invention; FIG. 8 is a perspective view of a generally cylindrical hub of the flap wheel shown in FIG. 7; FIG. 9 is a front view of the generally cylindrical hub shown in FIG. 8 including an end cap engaging the hub; FIG. 10 is a perspective view of the generally cylindrical hub and end cap shown in FIG. 9; FIG. 11 is a perspective view of an end cap for attachment to a generally cylindrical hub of a flap wheel in accordance with one embodiment of the present invention; FIG. 12 is a perspective view of a generally cylindrical hub for a flap wheel, in accordance with still another embodiment of the present invention; FIG. 13 is an enlarged view of a portion of the generally cylindrical hub shown in FIG. 12; and FIG. 14 is a front view of a cylindrical hub for a flap wheel in accordance with yet a further embodiment of the present invention. DETAILED DESCRIPTION Referring now to the Figures, which illustrate various embodiments of a rotary finishing device in accordance with the present invention. The rotary finishing devices can be utilized to finish a surface, such as by polishing, abrading or the like. However, it will be understood that the finishing devices disclosed herein can be utilized for a variety of different purposes and can be formed with a variety of different configurations. Moreover, the finishing media utilized with the disclosed finishing devices can also vary depending upon the application for which the finishing devices will be used and can include cloth, sandpaper or the like. It will also be understood that a variety of different finishing media may be utilized. Turning now to FIGS. 1 through 3, which illustrate one embodiment of a rotary finishing device in accordance with the present invention. The rotary finishing device 10 includes a generally circular hub 12, having an outer peripheral surface or outer periphery 14, and an inner peripheral surface or inner periphery 16. The inner periphery 16 defines a passageway or throughway 18 that is preferably open to either side of the device 10. The circular hub 12 is preferably formed from a metal, such as aluminum. However, it will be understood that a variety of other materials may also be utilized, including plastic. Further, the circular hub 10 is preferably formed by an extrusion process. However, again a variety of other processes may also be utilized to form the circular hub 12. The hubs can be formed with a variety of different diameters, widths, lengths and other configurations. This flexibility is not present in current devices, i.e. the ability to provide hubs of varying lengths. The outer periphery 14 of the device 10 includes a plurality of slots 20 formed thereabout. In this embodiment, the slots 20 are defined by a pair of side portions 22, 24 that extend generally outward from the outer periphery 14. It will be understood that the side portions 22, 24 of each of the slots 20 can extend in a variety of different directions, including inwardly. As shown best in FIG. 3, each side portion 22, 24 includes a tip portion 26, a base portion 28, and a side surface 30 extending between the base portion 28 and the tip portion 26. In this embodiment, the tip portions 26 have a greater width (w1) than the width (w2) of the base portions 28. This orientation assists in maintaining the side surfaces 30 generally parallel to one another such that each slot 20 is generally square or rectangular in shape. Additionally, the circular hub 12 has a center point or centerline 32, which corresponds to the axis of rotation of the device 10. A reference line exists that extends from the center point 32 to a point between the pair of side portions 22, 24, as is identified by number 34. When the reference line 34 continues outwardly it passes between each of the side portions 22, 24. Here, the side surfaces 30 lie generally parallel to the reference line 34. This provides side portions 22, 24 that are oriented generally perpendicular to the outer periphery 14 of the hub 12. Each of the slots 20 includes a finishing media 40 disposed therein. The finishing media 40 may be comprised of a single sheet of material or a plurality of sheets of material. The finishing media 40 is intended to contact a surface to be finished. The finishing media is disposed between a pair of side portions 22, 24 and its innermost portion 42 is located adjacent the outer periphery 14 of the device 10. In one embodiment, the finishing media 40 is secured within each of the slots by an adhesive, such as an epoxy. The adhesive is utilized to secure the finishing media within each slot 20 by affixing it to the outer periphery 14 of the hub 12 and the opposing side surfaces 30 of each of the side portions 22, 24. Obviously, the finishing media can be secured within each of the slots in a variety of suitable manners. The inner periphery 18 of the device 10 also includes a plurality of lugs 36 that extend generally inwardly therefrom. The lugs 36 allow for easy machining of the device 10 to true up the inside contact surface, by removing a certain portion of material from the tip 38 of at least some of the lugs 36. This provides significant material savings as well as a decrease in machining cost as only the lugs 36 require machining instead of the entire inner periphery 18 when that is used as the contact surface to drive the finishing device. The lugs 36 also allow the hub 12 to communicate with a shaft or end cap to allow easy driving thereof. It will be understood that the inner periphery 18 may alternatively be a generally smooth surface without any lugs 36. Moreover, any number of lugs may be utilized. For example, FIG. 14 illustrates a generally circular hub 52 having an outer periphery 54 and an inner periphery 56. The inner periphery 56 does not have any lugs, but instead is comprised of a smooth surface. FIGS. 4 through 6 illustrate another embodiment of a rotary finishing device in accordance with the present invention. The rotary finishing device 50 also includes a generally circular hub 52, having an outer peripheral surface or outer periphery 54, and an inner peripheral surface or inner periphery 56. The inner periphery 56 defines a passageway or throughhole 58 that is preferably open to either side of the device 50. Again, while the circular hub 12 is preferably formed from a metal, such as aluminum through an extrusion process, it can be formed form a variety of different materials, through different processes, and in a variety of different sizes and dimensions. The outer periphery 54 of the device 10 includes a plurality of slots 60 formed thereabout. In this embodiment, the slots 60 are defined by a pair of side portions 62, 64 that extend generally inward from the outer periphery 54. Again, it will be understood by one of ordinary skill in the art that the side portions 62, 64 of each of the slots 60 can extend in a variety of different directions, including outwardly and can take on a variety of different configurations. As shown best in FIG. 6, each side portion 62, 64 includes a tip portion 66, a base portion 68, and a side surface 70 extending between the base portion 68 and the tip portion 66. Again, in this embodiment, the tip portions 66 have a greater width (w1) than the width (w2) of the base portions 68. This orientation assists in maintaining the side surfaces 70 generally parallel to one another such that each slot 60 is generally square or rectangular in shape. Additionally, the circular hub 52 has a center point or centerline 72, which corresponds to the axis of rotation of the device 50. A reference line exists that extends from the center point 72 to a point between the pair of side portions 62, 64, as is identified by number 74. When the reference line 74 continues outwardly, it passes between each of the side portions 62, 64. Here, the side surfaces 70 are configured in a non-parallel orientation with respect to the reference line 74. In other words, the side portions 62, 64 are oriented at an angle with respect to the outer periphery 54. Each of the slots 60 includes a finishing media 76 disposed therein. The finishing media 76 may be comprised of a single sheet of material or a plurality of sheets of material. The finishing media 76 is intended to contact a surface to be finished. The finishing media 76 is disposed between a pair of side portions 62, 64 and its innermost portion 78 is located adjacent the outer periphery 54 of the device 50. In one embodiment, the finishing media 76 is secured within each of the slots 60 by an adhesive, such as an epoxy. The adhesive secures the finishing media 76 within each slot 60 by affixing it to a bottom surface 80 that extends between and connects the base portions 68 of a pair of adjacent side portions 62, 64. Obviously, the finishing media 76 can be secured within each of the slots 60 in a variety of suitable manners. The inner periphery 56 of the device 50 also includes a plurality of lugs 82 that extend generally inward therefrom. The lugs 82 allow for easy machining of the device 50 to true up the inside contact surface, by removing a certain portion of material from the tip 84 of at least some of the lugs 82. This provides significant material savings as well as a decrease in machining cost as only the lugs 82 require machining instead of the entire inner periphery 56 when that is used as the contact surface. The lugs 82 also allow the hub 52 to communicate with a shaft or end cap to allow easy driving thereof. It will be understood that the inner periphery 56 may alternatively be a generally smooth surface without any lugs. Moreover, any number of lugs may be utilized. For example, FIG. 14 illustrates a generally circular hub 52 having an outer periphery 54 and an inner periphery 56. The inner periphery 56 does not have any lugs, but instead is comprised of a smooth surface for engagement with another structure to effectuate driving of the device. FIGS. 7 through 10 illustrate still another embodiment of a rotary finishing device in accordance with the present invention. The rotary finishing device 90 also includes a generally circular hub 92, having an outer peripheral surface or outer periphery 94, and an inner peripheral surface or inner periphery 96. The inner periphery 56 defines a passageway or throughhole 98 that is preferably open to either side of the device 90. Again, while the circular hub 92 is preferably formed from a metal, such as aluminum through an extrusion process, it can be formed form a variety of different materials, through different processes, and in a variety of different sizes. The outer periphery 94 of the device 90 includes a plurality of slots 100 formed thereabout. In this embodiment, the slots 100 are defined by a pair of side portions 102, 104 that extend generally inward from the outer periphery 94. Again, it will be understood by one of ordinary skill in the art that the side portions 102, 104 of each of the slots 100 can extend in a variety of different directions, including outwardly and can take on a variety of different configurations. As shown best in FIG. 9, each side portion 102, 104 includes a tip portion 106, a base portion 108, and a side surface 110 extending between the base portion 108 and the tip portion 106. In this embodiment, each of the slots 100 is generally rounded in shape. Additionally, the circular hub 92 has a center point or centerline 112, which corresponds to the axis of rotation of the device 90. A reference line exists that extends from the center point 112 to a point between the pair of side portions 102, 104, as is identified by number 114. When the reference line 114 continues outwardly, it passes between each of the side portions 102, 104. The side surfaces 100 are oriented in a non-parallel relationship to the reference line 114. However, the side portions 102, 104 lie in a parallel plane to the reference plane 114 (or generally parallel thereto) and extend from the outer periphery 94 in a generally perpendicular direction. In this embodiment, the side surfaces 100 are also not oriented generally parallel to one another. Each of the slots 100 includes a finishing media 116 disposed therein. The finishing media 116 may be comprised of a single sheet of material or a plurality of sheets of material. The finishing media 116 is intended to contact a surface to be finished. The finishing media 116 is disposed between a pair of side portions 102, 104 and its innermost portion 118 is located adjacent the outer periphery 94 of the device 90. In one embodiment, the finishing media 116 is secured within each of the slots 100 by an adhesive, such as an epoxy. The adhesive secures the finishing media 116 within each slot 100 by affixing it within the rounded slot. Obviously, the finishing media 116 can be secured within each of the slots 100 in a variety of suitable manners. The inner periphery 96 of the device 90 also includes a plurality of lugs 122 that extend generally inwardly therefrom. The lugs 122 allow for easy machining of the device 90 to true up the inside contact surface, by removing a certain portion of material from the tip 124 of at least some of the lugs 122. This provides significant material savings as well as a decrease in machining cost as only the lugs 122 require machining instead of the entire inner periphery 96 when that is used as the contact surface. The lugs 122 also allow the hub 92 to communicate with a shaft or end cap 126 to allow easy driving thereof. It will be understood that the inner periphery 96 may alternatively be a generally smooth surface without any lugs. Moreover, any number of lugs may be utilized. Turning to FIGS. 9 through 11, which illustrate an end cap 126 for engagement with a rotary finishing device in accordance with the present invention. The end cap 126 is generally circular in shape and includes an outer perimeter 128, an outer side 130, an inner side 132, and an opening 134. The inner side 132 of the end cap 126 has an inner step 136 that is intended to be received in the throughhole 98 of the circular hub 92. In one embodiment, the inner step 136 includes a plurality of grooves 138 that are spaced about the periphery of the inner step 136. Each of the plurality of grooves 138 is intended to engage a respective one of the lugs 122. The end cap 126 is intended to receive a driving shaft through the opening 134. As the driving shaft rotates, it causes the end cap 126 to rotate, which is in communication with the finishing device through the lugs 122 causing it to rotate. It will be understood that the end cap 126 can take on a variety of configurations and can be configured to engage the circular hub 92 in a variety of different manners. For example, the end cap 126 can engage the circular hub 92 on the outer periphery 94. Alternatively, the inner periphery of the circular hub may be a generally smooth surface without lugs and the end cap may have a generally smooth inner step outer periphery to effectuate engagement with the circular hub, such as is exemplarily shown in FIG. 14. FIGS. 12 and 13 illustrate another embodiment of a rotary finishing device in accordance with the present invention. The rotary finishing device 140 also includes a generally circular hub 142, having an outer peripheral surface or outer periphery 144, and an inner peripheral surface or inner periphery 146. The inner periphery 146 defines a passageway or throughhole 148 that is preferably open to either side of the device 140. Again, while the circular hub 142 is preferably formed from a metal, such as aluminum through an extrusion process, it can be formed form a variety of different materials, through different processes, and in a variety of different sizes. The outer periphery 144 of the device 140 includes a plurality of slots 150 formed thereabout. In this embodiment, the slots 150 are defined by a pair of side portions 152, 154 that extend generally outward from the outer periphery 144. Again, it will be understood by one of ordinary skill in the art that the side portions 152, 154 of each of the slots 150 can extend in a variety of different directions, including inwardly and can take on a variety of different configurations. Each of the slots 150 is intended to receive a finishing media that is secured in each slot 150 in the same manner discussed above. As shown best in FIG. 13, each side portion 152, 154 includes a tip portion 156, a base portion 158, and a side surface 160 extending between the base portion 158 and the tip portion 156. Again, in this embodiment, the tip portions 156 have a greater width (w1) than the width (w2) of the base portions 158. This orientation assists in maintaining the side surfaces 160 generally parallel to one another such that each slot 150 is generally square or rectangular in shape. In this embodiment, the side surfaces 160 are shaped such that the distance between opposing tip portions 156 is less than the distance between opposing base portions 158. The circular hub 142 also has a center point or centerline 162, which corresponds to the axis of rotation of the device 140. A reference line exists that extends from the center point 162 to a point between the pair of side portions 152, 154. The configuration of the reference line in this embodiment corresponds to the reference line in FIG. 3. Here, the side portions 152, 154 are oriented generally parallel to the reference line and thus are oriented generally perpendicular to the outer periphery 144. This is despite the fact that the side surfaces 160 are disposed at a slight angle with respect to the reference line. Between each of the side portions 152, 154, the outer periphery 144 consists of a pair of inwardly sloping planar surfaces 166, 168. Each of these slopes terminates at a point from which a wedge 170 extends. Accordingly, each of the slots 150 includes a wedge 170 extending outwardly from the outer periphery 144. Each wedge 170 is generally pointed and acts to spread the sheets of the finishing media apart so that they are wide at the base and cannot be easily pulled from the slot. The wedge 170 thus assists in retaining the finishing media within each of the slots 150. Each of the slots 150 includes a finishing media (not shown) disposed therein. The finishing media may be comprised of a single sheet of material or a plurality of sheets of material. The finishing media is intended to contact a surface to be finished. The finishing media is disposed between a pair of side portions 152, 154 and its innermost portion is located adjacent the outer periphery 144 of the device 140. In one embodiment, the finishing media is secured within each of the slots 150 by an adhesive, such as an epoxy. The adhesive secures the finishing media within each slot 150 by affixing it within the rounded slot. Obviously, the finishing media can be secured within each of the slots in a variety of suitable manners. The inner periphery 146 of the device 140 also includes a plurality of lugs 164 that extend generally inwardly therefrom. The lugs 164 allow for easy machining of the device 140 to true up the inside contact surface, by removing a certain portion of material from the tip 166 of at least some of the lugs 164. This provides significant material savings as well as a decrease in machining cost as only the lugs 164 require machining instead of the entire inner periphery 146 when that is used as the contact surface. The lugs 164 also allow the hub 142 to communicate with a shaft or end cap to allow easy driving thereof. It will be understood that the inner periphery may alternatively be a generally smooth surface without any lugs. Moreover, any number of lugs may be utilized. While particular embodiments of the invention have been shown and described, numerous variations and alternate embodiments will occur to those skilled in the art. Accordingly, it is intended that the invention be limited only in terms of the appended claims.

<SOH> BACKGROUND OF INVENTION <EOH>The present invention relates generally to a rotary finishing device, and more particularly to a flap-type rotary finishing device having an epoxy attachment of the finishing media to a hub of the flap wheel. Rotary finishing tools are well known and typically include pieces or strips of a finishing medium. Such tools have proven to be very effective in the finishing of a wide variety of components such as those made from metal or the like. An exemplary rotary finishing tool utilizes generally rectangular pieces of abrasive paper, such as sandpaper, to provide a rotary abrasive device. One of the more common rotary finishing tools or devices is known in the art as a flap wheel. These flap wheels typically have annular arrays of flexible finishing strips and are commonly used in the finishing art. Most conventional rotary finishing devices consist of flexible strips each comprising sheets of material for finishing a surface of a piece. Many of these rotary finishing devices have abrasive particles bonded on one face thereof. Such rotary abrasive devices are useful for contoured polishing, cutting, or surface abrading of a variety of metal surfaces. Various fabrication methods for such a rotary device are known. One such conventional method requires that the finishing sheets have two notches in their opposite side edges near the base end of each strip. As the strips are arranged in an annular array, the notches form concentric circular depressions on opposite sides of the annular array. Suitable circular reinforcement mechanisms, such as two metallic end caps are mounted on opposite sides of the array. Each end cap has an inwardly extending lip, which engages the circular depressions to mechanically grip the inner ends of the finishing strips. This method thus relies on friction created between the two metallic end caps to maintain the base ends of the strips in contact with a hub of the rotary device. Although a rotary finishing device of this configuration performs suitably, its manufacture is rather expensive and requires two notches to be formed in each strip prior to assembly. The forming of these notches is both time consuming and costly. Further, the notches must be aligned properly with respect to each other to receive accurate placement of the metal end caps. Another known fabrication method for a rotary finishing device involves attaching the strips to an aluminum clip, such as by stapling. The metal clip with the attached strips is then loaded into a metal hub. A plurality of pins are then used to secure the hub to an end cap. These pins maintain the strips in communication with the metal hub, such that it is relatively difficult for the strips to become disengaged from the hub during polishing. However, these rotary devices are also relatively expensive and also require a relatively cumbersome assembly process. Yet another known fabrication process involves attaching the finishing media through the use of a suitable adhesive. This adhesive, such as an epoxy, is applied to the strips at their base ends to bond them to one another to form a unitary structure. The adhesive itself thus becomes the hub. Alternatively, a cardboard center is utilized to control the flow of adhesive. The cardboard center merely While these rotary devices are relatively inexpensive to produce, they are prone to breakage issues after high use. This breakage typically occurs due to failure of the epoxy, which is the weakest part of the device, as a result of the application of significant force during usage. When this breakage or failure of the rotary device occurs, a portion of the epoxy, together with the adhered strips, typically separates from the device. This results in an imbalanced rotary device, which requires replacement. Additionally, when the breakage occurs, because of the relatively high operating speeds of these devices, the separated portion can become a projectile, which can raise safety concerns or cause damage to the finishing device or surrounding apparatus. Therefore, a need exists for a rotary finishing device that is relatively inexpensive to manufacture, but has sufficient strength to withstand the high operating speeds to which these devices are subjected.

<SOH> SUMMARY OF INVENTION <EOH>One advantage of the present invention is to provide a rotary finishing device that is less expensive than prior rotary finishing devices. Another advantage of the present invention is to provide a rotary finishing device that decreases the assembly time of the device without compromising its strength or integrity. Yet another advantage of the present invention is to provide a rotary finishing device that can be more inexpensively manufactured for a wide variety of different applications. A further advantage of the present invention is to provide a rotary finishing device that can be manufactured in a variety of different widths and lengths. In accordance with the above and the other advantages of the present invention, a rotary finishing device is provided. The rotary finishing device includes a generally circular hub having an inner periphery and an outer periphery. The inner periphery defines a passageway therethrough. The outer periphery of the hub has a plurality of slots extending therefrom. Each of the plurality of slots is defined by a pair of side portions. Additionally, the plurality of slots are generally uniformly spaced around the outer periphery. Each of the plurality of slots includes at least one finishing sheet secured therein. The at least one finishing sheet is secured within each of the plurality of slots by an adhesive. Other advantages of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.

20040112

20050927

20050714

74097.0

NGUYEN, DUNG V

FLAP-TYPE ROTARY FINISHING DEVICE

SMALL

ACCEPTED

ACCEPTED

ELECTROSTATIC DISCHARGE INPUT AND POWER CLAMP CIRCUIT FOR HIGH CUTOFF FREQUENCY TECHNOLOGY RADIO FREQUENCY (RF) APPLICATIONS

A SiGe ESD (electrostatic discharge) power clamp circuit having a forward biased trigger device fabricated in a given technology and a clamp transistor preferably comprising a high frequency cutoff SiGe npn transistor, wherein the trigger device has a turn-on voltage which is below the Johnson Limit breakdown voltage of the highest frequency device fabricated in the given technology.

1. An electrostatic discharge device comprising: a forward biased trigger device fabricated in a given technology, wherein the trigger device is forward biased bv a voltage to conduct in a non-breakdown, non-rectifying mode of operation; a clamp transistor coupled to the trigger device so that activation of the trigger device activates the clamp transistor, the clamp transistor having a cutoff frequency which determines its Johnson Limit breakdown voltage; the trigger device being fabricated in the given technology and having a trigger activation voltage above which the trigger device activates the clamp transistor, with the trigger activation voltage being below the Johnson Limit breakdown voltage of the highest frequency device fabricated in the given technology. 2. The electrostatic discharge device of claim 1, wherein the trigger device is coupled to the base of the clamp transistor. 3. The electrostatic discharge device of claim 1, wherein the trigger device is constructed of a silicon germanium material. 4. The electrostatic discharge device of claim 1, wherein the clamp transistor is constructed of a silicon germanium material. 5. The electrostatic discharge device of claim 1, wherein the trigger device and the clamp transistor are coupled between an input pad and a ground. 6. The electrostatic discharge device of claim 1, wherein the trigger device and the clamp transistor are coupled between a power rail and a ground rail. 7. The electrostatic discharge device of claim 1, wherein the trigger device and the clamp transistor are coupled between a first power source and a second power source. 8. The electrostatic discharge device of claim 1, wherein the trigger device is constructed of a plurality of trigger elements in a series configuration. 9. The electrostatic discharge device of claim 1, wherein the trigger device includes at least one forward biased junction element in the group consisting of Si, SiGe and SiGeC. 10. The electrostatic discharge device of claim 1, wherein the trigger device includes at least one forward biased junction element in the group consisting of CMOS diodes, BiCMOS diodes, RF CMOS diodes, bipolar devices including Si, SiGe and SiGeC diode configured bipolar transistors and varactors, Schottky diodes in Si, SiGe and SiGeC, and MOSFETs. 11. A method of fabricating electrostatic discharge protection in an integrated circuit comprising the steps of: fabricating a forward biased trigger device in a given technology in the integrated circuit; fabricating a clamp transistor coupled to the trigger device in the integrated circuit so that activation of the trigger device activates the clamp transistor, the clamp transistor having a cutoff frequency which determines its Johnson Limit breakdown voltage; fabricating the trigger device in the given technology to have a trigger activation voltage above which the trigger device activates the clamp transistor, with the trigger device being forward biased bv a voltage to conduct in a non-breakdown, non-rectifying mode of operation, and the trigger activation voltage being below the Johnson Limit breakdown voltage of the highest frequency device fabricated in the given technology. 12. The method of claim 11, including fabricating the trigger device and the clamp transistor of a silicon germanium material. 13. The method of claim 11, including coupling the trigger device and the clamp transistor between an input pad and a ground. 14. The method of claim 11, including coupling the trigger device and the clamp transistor between a power source and a ground. 15. The method of claim 11, including fabricating the trigger device as at least one forward biased junction element in the group consisting of Si, SiGe and SiGeC 16. The method of claim 11, including fabricating the trigger device as at least one forward biased junction element in the group consisting of CMOS diodes, BiCMOS diodes, RF CMOS diodes, bipolar devices including Si, SiGe and SiGeC diode configured bipolar transistors and varactors, Schottky diodes in Si, SiGe and SiGeC, and MOSFETs. 17. A semiconductor device comprising: a first rail for providing a first voltage source; a second rail for providing a second voltage source; functional circuitry, coupled between the first and second rails, for performing an electrical function; electrostatic discharge circuitry, coupled between the first and second rails, for diverting electrostatic discharges from the functional circuitry onto either the first or second rail, the electrostatic discharge circuitry including: a forward biased trigger device fabricated in a given technology, wherein the trigger device is forward biased bv a voltage to conduct in a non-breakdown, non-rectifying mode of operation; a clamp transistor coupled to the trigger device so that activation of the trigger device activates the clamp transistor, the clamp transistor having a cutoff frequency which determines its Johnson Limit breakdown voltage; the trigger device having a trigger activation voltage above which the trigger device activates the clamp transistor, with the trigger activation voltage being below the Johnson Limit breakdown voltage of the highest frequency device fabricated in the given technology. 18. The semiconductor device of claim 17, wherein the trigger device and transistor are constructed of a silicon germanium material. 19. The semiconductor device of claim 17, wherein the trigger device includes at least one forward biased junction element in the group consisting of Si, SiGe and SiGeC. 20. The semiconductor device of claim 17, wherein the trigger device includes at least one forward biased junction element in the group consisting of CMOS diodes, BiCMOS diodes, RF CMOS diodes, bipolar devices including Si, SiGe and SiGeC diode configured bipolar transistors and varactors, Schottky diodes in Si, SiGe and SiGeC, and MOSFETs. 21. An integrated circuit comprising: a first rail for providing a first voltage source; a second rail for providing a second voltage source; functional circuitry, coupled between the first and second rails, for performing a desired function; electrostatic discharge circuitry, coupled between the first and second rails, for diverting electrostatic discharges from the functional circuitry onto either the first or second rail, the electrostatic discharge circuitry including: a forward biased trigger device fabricated in a given technology, wherein the trigger device is forward biased by a voltage to conduct in a non-breakdown, non-rectifying mode of operation; a clamp transistor coupled to the trigger device so that activation of the trigger device activates the clamp transistor, the clamp transistor having a cutoff frequency which determines its Johnson Limit breakdown voltage; the trigger device having a trigger activation voltage above which the trigger device activates the clamp transistor, with the trigger activation voltage being below the Johnson Limit breakdown voltage of the highest frequency device fabricated in the given technology. 22. The integrated circuit of claim 21, wherein the trigger device includes at least one forward biased junction element in the group consisting of Si, SiGe and SiG. 23. The semiconductor device of claim 21, wherein the trigger device includes at least one forward biased junction element in the group consisting of CMOS diodes, BiCMOS diodes, RF CMOS diodes, bipolar devices including Si, SiGe and SiGeC diode configured bipolar transistors and varactors, Schottky diodes in Si, SiGe and SiGeC, and MOSFETs.

BACKGROUND OF INVENTION 1. Field of the Invention The present invention relates generally to an electrostatic discharge input and power clamp circuit for high cutoff frequency technology radio frequency (RF) applications. More particularly, the subject invention relates to an electrostatic discharge input and power clamp circuit for high cutoff frequency technology RF applications with low voltage trigger elements and low power applications, and utilizing a forward biased junction trigger device and a low capacitance ESD NPN clamp transistor. 2. Discussion of the Prior Art The present invention relates generally to electrostatic discharge circuits, and more specifically pertains to electrostatic discharge power clamp circuits for high frequency RF applications. Electrostatic Discharge (ESD) events, which can occur both during and after manufacturing of an Integrated Circuit (IC), can cause substantial damage to the IC. ESD events have become particularly troublesome for CMOS and BiCMOS chips because of their low power requirements and extreme sensitivity. A significant factor contributing to this sensitivity to ESD is that the transistors of the circuits are formed from small regions of N-type materials, P-type materials, and thin gate oxides. When a transistor is exposed to an ESD event, the charge applied may cause an extremely high current flow to occur within the device, which can, in turn cause permanent damage to the junctions, neighboring gate oxides, interconnects and/or other physical structures. Because of this potential damage, on chip ESD protection circuits for CMOS and BiCMOS chips is essential. In general, such protection circuits require a high failure threshold, a small layout size and a low Resistive/Capacitive (RC) delay so as to allow high speed applications. An ESD event within an IC can be caused by a static discharge occurring at one of the power lines or rails. In an effort to guard the circuit against damage from the static discharge, circuits referred to as ESD clamps are used. An effective ESD clamp will maintain the voltage at the power line to a value which is known to be safe for the operating circuits, and not interfere with the operating circuits under normal operating conditions. An ESD clamp circuit is typically constructed between a positive power supply (e.g.VDD) and a ground plane, or a ground plane and a negative power supply (Vss). The main purpose of the ESD clamp is to reduce the impedance between the rails VDD and VSS so as to reduce the impedance between the input pad and the VSS rail (i.e. discharge of current between the input to VSS), and to protect the power rails themselves from ESD events. The never ending demand by consumers for increased speed in Radio Frequency (RF) devices has resulted in some unique challenges for providing ESD protection in these high speed applications. More specifically, the physical size (e.g. breakdown voltage) and loading effects of the ESD devices must now be considered in such high speed applications (e.g. 1-200 GHz range). The capacitive loading of the ESD device itself becomes a major concern for chips running at high frequencies, since the capacitive loading has an adverse effect on performance. For example, the capacitive loading effect of a typical ESD input device at a frequency of 1 GHz is 0.5 pF, 10 GHz -0.1 pF, and at 100 GHz -0.05pF, 200 GHz -0.01 pF. For an input pad, having a low capacitance and low trigger voltage ESD network are keys to provide ESD solutions for high speed circuits. Hence an input ESD device must have the highest performance element with the lowest capacitance and the lowest trigger condition. RF technologies can have a plurality of transistor frequencies (e.g. typically one, two or three). Moreover a high frequency transistor typically has a lower capacitance compared to a high breakdown transistor. For an ESD power clamp, it is important to provide a low voltage trigger condition to allow for a low voltage turn-on above the power supply voltage condition. For RF CMOS, Silicon Germanium (SiGe) and Silicon Germanium Carbon (SiGeC) technologies, the frequencies of the devices are increasing. Silicon Germanium technology current gain cutoff frequencies have increased to 120, 200 and 300 GHz. As the cutoff frequency increases, the architecture of the transistor is modified to address improved performance conditions. In each technology generation, the power supply voltage is reduced as well. Additionally, on input pins, circuits with small signal swings well below the power supply can allow for ESD input networks whose maximum signal swing is well below the BVCEO (breakdown voltage from collector to emitter) of the high fT (unity current gain cutoff frequency) transistor supported in a Bipolar or BiCMOS technology. There are transistor logic standards, such as open drain configurations, Gunning transistor logic (GTL) and potentially other standards, where the maximum voltage observed in a CMOS circuit (or BiCMOS, or pure Bipolar) network is such that the signal swing is well below the BVCEO of at least one transistor in the technology. For low power applications, the voltage can be set to a level well below the BVCEO of a transistor. For a SiGe transistor, a 100 GHz transistor will have a BVCEO of approximately 2 Volts, and a 200 GHz transistor will have a BVCEO of approximately 1 Volt. Additionally, the power supply of the semiconductor chip may be reduced in a mixed signal application. In this case, the power supply condition on CMOS circuits may be reduced. Additionally, the power supply condition on the product may be reduced for power saving, power management, and low power applications. To provide good ESD protection, it is then possible to provide an ESD input pad network or an ESD power clamp below the power supply conditions. The prior art as developed to date has been constrained by the Johnson Limit as discussed below in providing a low trigger voltage condition for ESD protection circuits, particularly on-chip ESD protection circuits for CMOS and BiCMOS chips for RF applications. It would, therefore, be a distinct advantage to have an ESD power clamp that could provide substantial benefits in high speed device technologies and provide a low trigger voltage condition for RF applications, mixed signal environments, and low power applications. The present invention provides such an ESD clamp. SUMMARY OF INVENTION The present invention provides an ESD power clamp with a low trigger voltage condition for high speed, high cutoff frequency RF applications, mixed signal environments, and low power applications. The present invention provides an ESD device that is useful in high speed radio frequency applications where turn-on voltage condition is a concern. In a preferred embodiment of the present invention, the trigger device utilizes a forward biased p-n diode device based configuration fabricated in a given technology and having a turn-on voltage that is lower than the Johnson Limit breakdown voltage of the highest frequency device fabricated in that given technology. For each technology generation the BVCEO of the clamp device decreases as a result of the relationship between the Johnson limit (which describes a fundamental relationship between the frequency response of a transistor device and the maximum power applied across the transistor device) and the current gain cutoff frequency. The present invention provides an ESD device that allows a trigger condition, by a forward biased trigger device implemented in a given technology, that is not limited to the BVCEO of the clamping device and is not limited to the Johnson Limit breakdown voltage of the fastest device in the technology of implementation. The trigger device is forward biased which means that the trigger device is biased by a voltage to conduct in a non-breakdown, non-rectifying mode of operation. The present invention provides an ESD device network that is suitable for implementation in CMOS, BiCMOS, or Bipolar circuits for standard or low power technologies. BRIEF DESCRIPTION OF DRAWINGS The foregoing objects and advantages of the present invention for an electrostatic discharge input and power clamp circuit for high cutoff frequency technology RF applications may be more readily understood by one skilled in the art with reference being had to the following detailed description of several embodiments thereof, taken in conjunction with the accompanying drawings wherein like elements are designated by identical reference numerals throughout the several views, and in which: FIG. 1 illustrates an exemplary circuit of a prior art SiGe ESD power clamp wherein a first stage low breakdown transistor device serves as a trigger for a second stage high breakdown clamp transistor device; FIG. 2 is a graph of the Johnson Limit curve illustrating in greater detail the trigger conditions for the prior art implementation and a comparison of the trigger conditions for the present invention; FIG. 3 is a schematic diagram illustrating one embodiment of an ESD clamp constructed in accordance with the teachings of the present invention utilizing a SiGe based varactor or diode trigger network; FIG. 4 is a schematic diagram illustrating another embodiment of an ESD clamp constructed in accordance with the teachings of the present invention utilizing a Schottky diode trigger network. FIG. 5 is a cross sectional view and diagram of an implementation of the clamp device as a SiGe Heterojunction Bipolar Transistor (HBT) according to the teachings of the present invention; FIG. 6 shows graphs of experimental results illustrating the operability of the present invention; FIG. 7 shows graphs of experimental results illustrating the operability of the present invention. FIG. 8 is a schematic diagram illustrating another embodiment of an ESD clamp constructed in accordance with the teachings of the present invention utilizing a BiCMOS p-n diode trigger network. FIG. 9 is a schematic diagram illustrating another embodiment of an ESD clamp constructed in accordance with the teachings of the present invention utilizing a lateral polysilicon-bound diode trigger network. FIG. 10 is a schematic diagram illustrating another embodiment of an ESD clamp constructed in accordance with the teachings of the present invention utilizing a pseudozero VT MOSFET trigger network FIG. 11 is a schematic diagram illustrating another embodiment of an ESD clamp constructed in accordance with the teachings of the present invention utilizing a dynamic threshold MOSFET trigger network. DETAILED DESCRIPTION FIG. 1 illustrates an exemplary circuit of a prior art SiGe ESD power clamp wherein a first stage low breakdown transistor device serves as a trigger for a second stage high breakdown clamp transistor device. The first stage trigger transistor has a resistor Rbias in series therewith between power supplies VDD and VSS, and the second stage clamp transistor has a resistor Rballast in series therewith between the power supplies VDD and VSS. The circuit of FIG. 1 is a common emitter circuit with SiGe or SiGeC devices having floating bases, wherein the devices closely approximate the Johnson Limit curve. FIG. 1 illustrates an exemplary Darlington configured bipolar power clamp circuit with a sub-native trigger voltage. For this configuration to be suitable as an ESD power clamp, we can take advantage of the inverse relationship between the BVCEO and the fT of the device. For a power clamp, the clamp device must have a high breakdown voltage in order to address the functional potential between the VCC power supply and ground potential. This power clamp requires a fT above the ESD pulse frequency to discharge the current effectively. For the trigger device, a low breakdown voltage device is needed in order to initiate base current into the clamp device at an early enough voltage. The present invention capitalizes upon the recognition that the structural and physical characteristics of Silicon Germanium (SiGe) material and other equivalent materials (e.g. Silicon Germanium Carbon (SiGeC)) are ideal for use in an ESD clamp for high speed applications. More specifically, the present invention recognizes that the scaling of the SiGe or SiGeC heterojunction bipolar transistor is driven by both structural changes and the physical limitations of the transistor itself, and that such recognitions can be used where BVCEO conditions are important. An equation (PmXc)½fT=Emvs/2π known as the Johnson Limit describes a fundamental relationship between the frequency response of the transistor and the maximum power applied across the transistor element. Pm represents the maximum power, Xc represents the reactance (Xc=½πfTCbc), fT represents the unity current gain cutoff frequency, Em represents the maximum electric field, and vs represents the electron saturation velocity. The equation can be transposed so that is it is expressed in terms of maximum voltage Vm=Emvs/2πfT to illustrate the inverse relationship between the transistor speed and the allowed breakdown voltage. FIG. 2 is a graph illustrating in greater detail the Johnson Limit curve and approximations of how transistors constructed of Silicon and SiGe compare. In this diagram, the x-axis represents fT, and the y-axis represents the Breakdown Voltage of the transistor from the collector-to-emitter (BVCEO). The curve demonstrates that the BVCEO of the transistor decreases with an increase in the unity current gain cutoff frequency (fT). FIG. 2 is a graph illustrating the frequency cutoff and BVCEO characteristics of trigger and clamp devices constructed in accordance with the teachings of the present invention wherein N=1, 2 or 3 trigger and clamp devices as discussed below. As previously discussed and illustrated in FIG. 1, a transistor constructed from SiGe or SiGeC material closely approximates the Johnson Limit curve. The present invention recognizes this by developing a trigger condition of the trigger device which is lower than the Johnson Limit breakdown voltage of the fastest device in the technology of implementation and the BVCEO of the clamp device. More specifically, the present invention uses a first ESD trigger circuit and a second ESD device having a high fT/low BVCEO. In this configuration, the capacitive loading of the ESD input device is reduced to a respectable level. This can provide an ESD clamp device placed on the power rail having a low voltage power clamp. ESD trigger device is preferably a forward biased junction element in Si or SiGe or SiGeC and comprises the following general categories of junction elements: 1. CMOS, BiCMOS and RF CMOS diodes, including Si LOCOS defined pn diodes, Si shallow trench isolation defined pn diodes with a medium or deep trenches, polysilicon gate defined pn diodes, all of which can be in Si, SiGe or SiGeC technologies, in either P well or N well, and all of which can include features of subcollectors, trench isolation, with medium or deep trench structures; 2. bipolar devices, including Si, SiGe or SiGeC diode configured bipolar npn or pnp transistors as two element components, Si, SiGe or SiGeC varactors, usually configured base-collector; 3. Schottky diodes in either Si, SiGe or SiGeC; 4. MOSFETs, in either P channel or N channel, including low voltage trigger MOSFETs, gate modulated pseudozero VT MOSFETs, depletion MOSFETs and dynamic threshold MOSFET diodes. FIG. 3 is a schematic diagram illustrating an ESD clamp constructed in accordance with the teachings of the present invention utilizing a SiGe based varactor or diode trigger network with a sub-native trigger voltage. In the embodiment of FIG. 3, one SiGe varactor element, or a number of SiGe varactor elements placed in series, are used as the trigger device in an ESD clamp circuit. Utilization of a single varactor element allows the trigger condition to be set at a minimum turn-on voltage of the varactor (e.g. 0.7 Volts), plus the turn on voltage of the SiGe (or SiGeC) emitter base voltage of the clamp element (e.g. 0.7 Volts) leading to a turn on voltage of 1.4 Volts. This trigger condition can be increased by adding more varactor elements in series. Hence states of 1.4, 2.1, and 2.8 V are achievable with additional elements. Adding more elements reduces the observed capacitance of the trigger element, but impacts the turn-on voltage and the size of the structure. The capacitance of the varactor structure can be reduced by utilizing the trench and non-subcollector solutions as discussed herein. An alternative embodiment can use an SiGe npn transistor with its emitter base shorted, and utilize the basecollector Vbc voltage to provide the trigger condition, or alternatively, to provide a lower capacitance trigger, the base-emitter junction of a SiGe npn device can be utilized which has a lower capacitance than the base-collector junction. For input pad applications, usage of this network provides a low capacitance trigger network reducing the device loading shorting (or across) the base-collector. More generally, the trigger condition can be provided by a diode configured npn SiGe transistor (using the base-emitter voltage with the collector-base shorted, or a diode configured pnp SiGe transistor (using the emitter-base voltage with the collector-base shorted, or the collector-base voltage with the emitter-base shorted). For the trigger and clamp devices, the frequency response of the clamping device is not critical for ESD applications. The capacitance of the subcollector can be reduced by using a medium depth trench isolation whose depth extends shallower than the subcollector depth. Additionally, the ESD trigger element or ESD Clamp element can achieve a lower capacitance by an extension of the trench isolation well below the subcollector junction depth. Additionally, the trigger element can achieve a lower capacitance by elimination of the subcollector implant from the collector region. Elimination of the subcollector implant reduces the collector-to-substrate capacitance thereby lowering the trigger element capacitance. This provides a lower capacitance ESD network for the trigger element and the clamp element. The use of a lower breakdown voltage trigger device ensures the turning on of the trigger element prior to the turning on of the clamp element. This is important because the turning on of the clamp element prevents a non-uniform current constriction within the clamp element from adversely affecting the ESD robustness with increased scaling of the clamp element length in high frequency applications. FIG. 4 is a schematic diagram of another embodiment of an ESD clamp constructed in accordance with the teachings of the present invention utilizing a Schottky diode trigger network with a sub-native trigger voltage. A SiGe-based Schottky diode network provides a lower trigger voltage than a CMOS diode, a SiGe npn or a diode configured SiGe transistor or a SiGe varactor structure. By utilizing a single Schottky diode, a trigger condition can be set to 0.3 V plus the Vbe of the SiGe clamp transistor (0.9 Volts). Additionally, by placing multiple Schottky diodes in series, trigger conditions of 0.9, 1.2, and 1.5 V are obtainable with 1, 2, and 3 Schottky diodes placed in series. The Schottky diode capacitance can be reduced by trench isolation, and subcollector elimination (non-subcollector implementation) of the Schottky structure. The present invention can selectively combine and mix diode-configured SiGe npn transistors, SiGe based varactors and Schottky based elements in series to achieve different trigger conditions. Hence it should be apparent that a hybrid network of these elements in a series configuration can provide selected new voltage conditions as well as capacitance loading advantages. Utilization of the ESD circuit in CMOS or RF CMOS networks provides the trigger element and clamp element with a higher frequency response while making them less sensitive to spurious noise spikes and electrostatic emissions (EMI) events. The ballast resistor Rballast is placed in series with the clamp device, and is used in a conventional fashion for providing emitter stability, voltage limitations, thermal stability, and ESD stability. The bias resistor Rbias is placed in series with trigger device, and is used to maintain the base of the clamp device at a low potential in order to limit the amount of current that flows through the trigger device during an ESD event. Formation of a trigger device and clamp transistor can be initiated using two different collector designs in a common process. FIG. 5 is a cross sectional view of an implementation of the trigger device as a SiGe varactor according to the teachings of the present invention. The SiGe varactor is formed on a n++ subcollector. The SiGe epitaxial film is placed on the silicon surface forming the extrinsic base over the STI isolation and the intrinsic base region over the single crystal silicon region. An n+ pedestal implant is formed through the emitter window. FIG. 5 illustrates a SiGe HBT (Heterojunction Bipolar Transistor) structure. The SiGe HBT devices are designed on a p-substrate. An n++ subcollector is formed in the p-substrate followed by an epitaxial growth. Shallow trench isolation and deep trench isolation are formed prior to the epitaxial base SiGe film growth. A first n+ pedestal implant is done to allow the collector implants to move closer to the silicon surface. The SiGe epitaxial film is placed on the silicon surface forming the extrinsic base over the STI isolation and the intrinsic base region over the single crystal silicon region. To form a high fT SiGe HBT device, a second n+ pedestal region is implanted through the emitter window of only one SiGe HBT. The pedestal implant is typically formed to reduce the Kirk effect. The Kirk effect is due to a high current density which forces the space charge region of the base-collector junction to get pushed into the collector region. This reduces the frequency response of the transistor. To prevent this, the extra pedestal implant is placed so to maintain a high fT device, which in turn causes a low BVCEO breakdown voltage. As a result, the high fT/low BVCEO device can serve as a frequency responsive low breakdown voltage for the trigger of the Darlington configured network. The second transistor which does not have the second pedestal implant can serve as the high BVCEO/ low fT device. Obviously, more pedestal implants can be added to lower the BVCEO until a desired level is obtained. The SiGe varactor without the pedestal implant allows for a lower capacitance and lower leakage structure for a low capacitance ESD element. In this embodiment, Si diodes can be utilized where the anode is a shallow trench isolation defined p+ implant, and the cathode is a shallow trench isolation defined implant. This can utilize medium depth trench isolation and deep trench isolation for the sidewall of the element's cathode structure for latchup, isolation, injection and density advantages. This Si diode element can utilize n-wells, p-wells, n+ subcollector structures, collector structures, and trench structures for ESD and capacitance reduction advantages. The SiGe HBT ESD Power Clamp network trigger network consists of a high fT SiGe HBT with a bias resistor. When the transistor collector-to-emitter voltage is below the breakdown voltage, no current is flowing through the trigger transistor. The bias resistor holds the base of the SiGe HBT clamp transistor to a ground potential. With no current flowing, the output clamp can be visualized as a grounded base npn device between the power supplies. When the voltage on VCC exceeds the collector-to-emitter breakdown voltage, BVCEO, in the high fT SiGe HBT, current flows into the base of the SiGe HBT high breakdown device. This leads to discharging of the current on the VCC electrode to the VSS ground electrode. In the case with no trigger device, the SiGe HBT power clamp will undergo breakdown according to the condition similar to the grounded base npn transistor in common emitter configuration. To quantify the condition of snap-back of the clamp element, the terminal conditions when the partial derivative of the terminal current with respect to the terminal voltage goes to infinity. Assuming no ballasting resistor and no base resistance, it can be shown that ∂ I ∂ V = ∂ M ∂ V ⁢ { α ⁢ ⁢ I E + I gen } [ 1 - α ⁢ ⁢ M 1 + 1 R bias ⁢ kT q ⁢ I E ] → ∞ where the avalanche condition is modified by the bias resistor as α ⁢ M = 1 + 1 R bias ⁢ kT q ⁢ 1 I E This sets a BVCER condition on the clamp device as BV CER = BV CBO ⁢ 1 - α 1 + kT q ⁢ 1 R bias ⁢ 1 I E n This condition is the case where the base resistance is negligible. In our implementation, the trigger device will be lower than the BVCER value when a high fT/low BVCEO device is used. If the same transistor is used, the trigger device will be in a floating-base configuration, and the clamp device will be in the above condition with the additional current source from the triggering transistor. The bias resistor causes the clamp device to exceed the floating base condition. As the bias resistor increases, eventually, the clamp voltage will begin to appear as an open-base type condition. For an open-base trigger element, the collector current equals the emitter current with the condition of I C Trigger = I E Trigger = MI co ⁡ ( 1 + β ) 1 - β ⁡ ( M - 1 ) where the current gain is the current gain of the trigger device. This current serves as the base current to the clamp transistor. If we assume that the current flow through the bias transistor is small, this current will flow into the base of the clamp device. In the condition that the clamp is not in an avalanche state, and the trigger device is the current through the clamp is I C Clamp = β Clamp ⁢ MI co ⁡ ( 1 + β TR ) 1 - β TR ⁡ ( M - 1 ) As the voltage exceeds the breakdown voltage of the clamp element, both the trigger and clamp device will be in an avalanche state. In this condition a more general expression is need to quantify the operation. Alternative embodiments of both the clamp and trigger devices can be created by adding additional pedestal and/or CMOS N-well implants. For example, such implants could be used to create three distinct transistors, each having a differing fT. Alternative embodiments of both the clamp and trigger devices can be created by adding additional pedestal and/or CMOS N-well implants. FIGS. 6 and 7 show illustrations of the operability of the ESD network discussed in FIG. 3. Transmission line pulse (TLP) testing results show the operation with and without ballasting resistors. In this embodiment, the size of the structure was modified to determine ESD scaling results. These measurements are from the IBM SiGe 8T technology utilizing a 200 GHz ft transistor element as the clamp element and a 200 GHz fT transistor trigger element, which is in a B—C diode configuration (E-B shorted). FIG. 8 is a schematic diagram illustrating another embodiment of an ESD clamp constructed in accordance with the teachings of the present invention utilizing an BiCMOS diode trigger network 80. BiCMOS diodes can consist of shallow trench isolation (STI) defined p+ anode and STI-defined n+ cathode region. This structure can exist in a p-well or an n-well. In the case of the n-well region, the n-well tub becomes the cathode structure and the STI-defined region becomes the electrical contact to the n-well region. An additional n++ sub-collector can be placed in the n-well region or additional n-implants. The n-well region can be in a p-substrate. The edges of the n-well region can consists of n+ reach-through implants, trench isolation (TI), or deep trench (DT) structures. In the case of a p-well, the p-well becomes the anode structure and the STI-defined n+ region becomes the cathode structure. This p-well can be bound by an n-well edge, a n+ reach-through, an n-band, a sub-collector, trench isolation (TI) or deep trench (DT) isolation. In this implementation, a single element or a plurality of elements in a series configuration can be used. FIG. 9 is a schematic diagram illustrating another embodiment of an ESD clamp constructed in accordance with the teachings of the present invention utilizing a BiCMOS lateral polysilicon-bound gated diode trigger network 90. In this structure, instead of the p+ anode and n+ cathode being defined by the shallow trench isolation (STI), a polysilicon MOSFET gate structure serves as a means to define the anode and cathode connections. In this case, the lateral p-n diode is formed using a thin dielectric with a polysilicon film and spacer forming a MOSFET polysilicon gate structure. Source and drain implants as welll as halos, low-doped drain implants, extension implants and other MOSFET angled implants that form the MOSFET drain structure are present in the polysilicon gated diode structure. The gate structure has the p+ implants on half of the polysilicon film, and the n+ implants on the other half of the polysilicon film, which is achieved using the block masks used for MOSFET n- and p-channel device formation. This structure can exists in a p-well or an n-well. In the case of the n-well region, the n-well tub becomes the cathode structure and the polysilicon-defined region becomes the electrical contact to the n-well region. An additional n++ sub-collector can be placed in the n-well region or additional n-implants. The n-well region can be in a p-substrate. The edges of the n-well region can consists of n+ reach-through implants, trench isolation (TI), or deep trench (DT) structures. In the case of a p-well, the p-well becomes the anode structure and the polysilicon-defined n+ region becomes the cathode structure. This p-well can be bound by an n-well edge, an n+ reach-through, an n-band, a sub-collector, trench isolation (TI) or deep trench (DT) isolation. In this implementation, a single element or a plurality of elements in a series configuration can be used. FIG. 10 is a schematic diagram illustrating another embodiment of an ESD clamp constructed in accordance with the teachings of the present invention utilizing a pseudozero VT MOSFET trigger network 100. In this implementation, a MOSFET with a gate control network can be used to serve as a trigger voltage. The MOSFET element is placed between the power supply voltage VDD and the bipolar base node. A reference control network consisting of resistors or other elements in a resistive configuration sets the voltage to allow turn-on of the MOSFET. This voltage reference can be set to define the turn-on voltage of the network. In this implementation, a single element or a plurality of elements in a series configuration can be used. FIG. 11 is a schematic diagram illustrating another embodiment of an ESD clamp constructed in accordance with the teachings of the present invention utilizing a dynamic threshold MOSFET trigger network 110. In this embodiment, the MOSFET gate, drain and body are all connected to the VDD node and the source is connected to the base of the bipolar transistor. As the body rises, the threshold voltage of the MOSFET turns on. As the body rises, the threshold decreases, and the current drive of the MOSFET increases due to a larger VG-VT increase. This provides a low voltage trigger element which can be below the Johnson Limit condition of the bipolar elements. In this embodiments, the dynamic threshold MOSFET can be a singular element or a plurality of elements in a series configuration for the trigger circuit. While several embodiments and variations of the present invention for an electrostatic discharge input and power clamp circuit for high cutoff frequency technology RF applications are described in detail herein, it should be apparent that the disclosure and teachings of the present invention will suggest many alternative designs to those skilled in the art.

<SOH> BACKGROUND OF INVENTION <EOH>1. Field of the Invention The present invention relates generally to an electrostatic discharge input and power clamp circuit for high cutoff frequency technology radio frequency (RF) applications. More particularly, the subject invention relates to an electrostatic discharge input and power clamp circuit for high cutoff frequency technology RF applications with low voltage trigger elements and low power applications, and utilizing a forward biased junction trigger device and a low capacitance ESD NPN clamp transistor. 2. Discussion of the Prior Art The present invention relates generally to electrostatic discharge circuits, and more specifically pertains to electrostatic discharge power clamp circuits for high frequency RF applications. Electrostatic Discharge (ESD) events, which can occur both during and after manufacturing of an Integrated Circuit (IC), can cause substantial damage to the IC. ESD events have become particularly troublesome for CMOS and BiCMOS chips because of their low power requirements and extreme sensitivity. A significant factor contributing to this sensitivity to ESD is that the transistors of the circuits are formed from small regions of N-type materials, P-type materials, and thin gate oxides. When a transistor is exposed to an ESD event, the charge applied may cause an extremely high current flow to occur within the device, which can, in turn cause permanent damage to the junctions, neighboring gate oxides, interconnects and/or other physical structures. Because of this potential damage, on chip ESD protection circuits for CMOS and BiCMOS chips is essential. In general, such protection circuits require a high failure threshold, a small layout size and a low Resistive/Capacitive (RC) delay so as to allow high speed applications. An ESD event within an IC can be caused by a static discharge occurring at one of the power lines or rails. In an effort to guard the circuit against damage from the static discharge, circuits referred to as ESD clamps are used. An effective ESD clamp will maintain the voltage at the power line to a value which is known to be safe for the operating circuits, and not interfere with the operating circuits under normal operating conditions. An ESD clamp circuit is typically constructed between a positive power supply (e.g.VDD) and a ground plane, or a ground plane and a negative power supply (V ss ). The main purpose of the ESD clamp is to reduce the impedance between the rails V DD and V SS so as to reduce the impedance between the input pad and the V SS rail (i.e. discharge of current between the input to V SS ), and to protect the power rails themselves from ESD events. The never ending demand by consumers for increased speed in Radio Frequency (RF) devices has resulted in some unique challenges for providing ESD protection in these high speed applications. More specifically, the physical size (e.g. breakdown voltage) and loading effects of the ESD devices must now be considered in such high speed applications (e.g. 1-200 GHz range). The capacitive loading of the ESD device itself becomes a major concern for chips running at high frequencies, since the capacitive loading has an adverse effect on performance. For example, the capacitive loading effect of a typical ESD input device at a frequency of 1 GHz is 0.5 pF, 10 GHz -0.1 pF, and at 100 GHz -0.05pF, 200 GHz -0.01 pF. For an input pad, having a low capacitance and low trigger voltage ESD network are keys to provide ESD solutions for high speed circuits. Hence an input ESD device must have the highest performance element with the lowest capacitance and the lowest trigger condition. RF technologies can have a plurality of transistor frequencies (e.g. typically one, two or three). Moreover a high frequency transistor typically has a lower capacitance compared to a high breakdown transistor. For an ESD power clamp, it is important to provide a low voltage trigger condition to allow for a low voltage turn-on above the power supply voltage condition. For RF CMOS, Silicon Germanium (SiGe) and Silicon Germanium Carbon (SiGeC) technologies, the frequencies of the devices are increasing. Silicon Germanium technology current gain cutoff frequencies have increased to 120, 200 and 300 GHz. As the cutoff frequency increases, the architecture of the transistor is modified to address improved performance conditions. In each technology generation, the power supply voltage is reduced as well. Additionally, on input pins, circuits with small signal swings well below the power supply can allow for ESD input networks whose maximum signal swing is well below the BVCEO (breakdown voltage from collector to emitter) of the high f T (unity current gain cutoff frequency) transistor supported in a Bipolar or BiCMOS technology. There are transistor logic standards, such as open drain configurations, Gunning transistor logic (GTL) and potentially other standards, where the maximum voltage observed in a CMOS circuit (or BiCMOS, or pure Bipolar) network is such that the signal swing is well below the BVCEO of at least one transistor in the technology. For low power applications, the voltage can be set to a level well below the BV CEO of a transistor. For a SiGe transistor, a 100 GHz transistor will have a BV CEO of approximately 2 Volts, and a 200 GHz transistor will have a BV CEO of approximately 1 Volt. Additionally, the power supply of the semiconductor chip may be reduced in a mixed signal application. In this case, the power supply condition on CMOS circuits may be reduced. Additionally, the power supply condition on the product may be reduced for power saving, power management, and low power applications. To provide good ESD protection, it is then possible to provide an ESD input pad network or an ESD power clamp below the power supply conditions. The prior art as developed to date has been constrained by the Johnson Limit as discussed below in providing a low trigger voltage condition for ESD protection circuits, particularly on-chip ESD protection circuits for CMOS and BiCMOS chips for RF applications. It would, therefore, be a distinct advantage to have an ESD power clamp that could provide substantial benefits in high speed device technologies and provide a low trigger voltage condition for RF applications, mixed signal environments, and low power applications. The present invention provides such an ESD clamp.

<SOH> SUMMARY OF INVENTION <EOH>The present invention provides an ESD power clamp with a low trigger voltage condition for high speed, high cutoff frequency RF applications, mixed signal environments, and low power applications. The present invention provides an ESD device that is useful in high speed radio frequency applications where turn-on voltage condition is a concern. In a preferred embodiment of the present invention, the trigger device utilizes a forward biased p-n diode device based configuration fabricated in a given technology and having a turn-on voltage that is lower than the Johnson Limit breakdown voltage of the highest frequency device fabricated in that given technology. For each technology generation the BV CEO of the clamp device decreases as a result of the relationship between the Johnson limit (which describes a fundamental relationship between the frequency response of a transistor device and the maximum power applied across the transistor device) and the current gain cutoff frequency. The present invention provides an ESD device that allows a trigger condition, by a forward biased trigger device implemented in a given technology, that is not limited to the BV CEO of the clamping device and is not limited to the Johnson Limit breakdown voltage of the fastest device in the technology of implementation. The trigger device is forward biased which means that the trigger device is biased by a voltage to conduct in a non-breakdown, non-rectifying mode of operation. The present invention provides an ESD device network that is suitable for implementation in CMOS, BiCMOS, or Bipolar circuits for standard or low power technologies.

20040128

20050920

20050728

96584.0

QUINTO, KEVIN V

ELECTROSTATIC DISCHARGE INPUT AND POWER CLAMP CIRCUIT FOR HIGH CUTOFF FREQUENCY TECHNOLOGY RADIO FREQUENCY (RF) APPLICATIONS

UNDISCOUNTED

ACCEPTED

ACCEPTED

[LED DEVICE, FLIP-CHIP LED PACKAGE AND LIGHT REFLECTING STRUCTURE]

A light emitting diode (LED) device is provided. The LED device includes a device substrate, a first doped layer of a first conductivity type, a light emitting layer, a second doped layer of a second conductivity type, a transparent conductive oxide layer, a reflecting layer and two electrodes. The first doped layer is deposited on the device substrate, the light emitting layer is deposited on a portion of the first doped layer, and the second doped layer is deposited on the light emitting layer. The first and the second doped layers are comprised of III-V semiconductor material respectively. The transparent conductive oxide layer is deposited on the second doped layer, and the reflecting layer is deposited on the transparent conductive oxide layer. The two electrodes are deposited on the reflecting layer and the first doped layer respectively.

1. A light emitting diode (LED) device, comprising: a device substrate; a first doped layer, formed on the device substrate; a light emitting layer, formed on the first doped layer; a second doped layer, formed on the light emitting layer, wherein the second doped layer and the first doped layer are comprised of a semiconductor material of a III-V group compound with different conductivity type; a strained-layer superlattice contact layer a transparent conductive oxide layer as an ohmic contact layer, wherein the transparent conductive oxide layer is deposited on the strained-layer superlattice contact layer; a reflecting layer, deposited on the transparent conductive oxide layer; and two electrodes, formed on the reflecting layer and a portion of the first doped layer, respectively. 2. The LED device of claim 1, wherein a thickness of the transparent conductive oxide layer is (2 m+1)λ/2n (m is 0 or a positive integer), wherein λ is a wavelength of a light emitted from the light emitting layer and n is a refractive index of the transparent conductive oxide layer. 3. The LED device of claim 1, wherein the strained-layer superlattice contact layer comprise n-type or p-type III-V semiconductor multi-layer structures. 4. The LED device of claim 1, wherein the semiconductor material of the III-V group compound is gallium nitride (GaN), gallium phosphide (GaP) or gallium phosphide arsenide (GaAsP). 5. The LED device of claim 1, wherein the light emitting layer comprise a quantum-well light emitting layer. 6. The LED device of claim 1, wherein a material of the transparent conductive oxide layer is indium tin oxide (ITO), cerium tin oxide (CTO), antimony tin oxide (ATO), aluminum zinc oxide (AZO) indium zinc oxide (IZO), zinc oxide (ZnO), cadmium tin oxide, ZnGa2O4, SnO2:Sb, Ga2O3:Sn, AgInO2:Sn, In2O3:Zn, CuAlO2, LaCuOS, NiO, or CuGaO2, SrCu2O2. 7. The LED device of claim 1, wherein the first doped layer is comprised of a N-type doped layer, and the second doped layer is comprised of a P-type doped layer. 8. The LED device of claim 1, wherein the first doped layer is comprised of a P-type doped layer, and the second doped layer is comprised of a N-type doped layer. 9. A light emitting diode (LED) device, comprising: a device substrate; a first doped layer, formed on the device substrate; a light emitting layer, formed on the first doped layer; a second doped layer, formed on the light emitting layer, wherein the second doped layer and the first doped layer are comprised of a semiconductor material of a III-V group compound with different conductivity type; a strained-layer superlattice contact layer; a transparent conductive oxide layer as an ohmic contact layer, wherein the transparent conductive oxide layer is deposited on the strained-layer superlattice contact layer; a transparent insulating layer as a passivation layer, wherein the transparent insulating layer is deposited on transparent conductive oxide layer; a reflecting layer, deposited on the transparent insulating layer and a portion of the transparent conductive oxide layer; and two electrodes, formed on the reflecting layer and a portion of the first doped layer, respectively. 10. The LED device of claim 9, wherein a thickness of the transparent conductive oxide layer is (2 m+1)λ/2n (m is 0 or a positive integer), wherein λ is a wavelength of a light emitted from the light emitting layer and n is a refractive index of the transparent conductive oxide layer. 11. The LED device of claim 9, wherein a thickness of the transparent insulating layer is (2 m+1)λ/2k (m is 0 or a positive integer), wherein λ is a wavelength of a light emitted from the light emitting layer and k is a refractive index of the transparent insulating layer. 12. The LED device of claim 9, wherein the strained-layer superlattice contact layer comprise n-type or p-type III-V semiconductor multi-layer structures. 13. The LED device of claim 9, wherein the semiconductor material of the III-V group compound is gallium nitride (GaN), gallium phosphide (GaP) or gallium phosphide arsenide (GaAsP). 14. The LED device of claim 9, wherein the light emitting layer comprise a quantum-well light emitting layer. 15. The LED device of claim 9, wherein a material of the transparent conductive oxide layer is indium tin oxide (ITO), cerium tin oxide (CTO), antimony tin oxide (ATO), aluminum zinc oxide (AZO) indium zinc oxide (IZO), zinc oxide (ZnO), cadmium tin oxide, ZnGa2O4, SnO2:Sb, Ga2O3:Sn, AgInO2:Sn, In2O3:Zn, CuAlO2, LaCuOS, NiO, or CuGaO2, SrCu2O2. 16. The LED device of claim 9, wherein a material of the transparent conductive oxide layer is SiO2, SiN, Al2O3, AlN, BeO, ZnO. 17. The LED device of claim 9, wherein the first doped layer is comprised of a N-type doped layer, and the second doped layer is comprised of a P-type doped layer. 18. The LED device of claim 9, wherein the first doped layer is comprised of a P-type doped layer, and the second doped layer is comprised of a N-type doped layer. 19. A flip-chip light emitting diode (LED) package structure, comprising: a package substrate; and a LED device, faced-down and flipped on the package substrate and electrically connected to the package substrate, wherein the LED device comprises: a device substrate; a first doped layer, formed on the device substrate; a light emitting layer, formed on the first doped layer; a second doped layer, formed on the light emitting layer, wherein the second doped layer and the first doped layer are comprised of a semiconductor material of a III-V group compound with different conductivity type; a strained-layer superlattice contact layer a transparent conductive oxide layer as an ohmic contact layer, wherein the transparent conductive oxide layer is deposited on the strained-layer superlattice contact layer; a reflecting layer, deposited on the transparent conductive oxide layer; and two electrodes, formed on the reflecting layer and a portion of the first doped layer, respectively. 20. The flip-chip LED package structure of claim 19, wherein a thickness of the transparent conductive oxide layer is (2 m+1)λ/2n (m is 0 or a positive integer), wherein λ is a wavelength of a light emitted from the light emitting layer and n is a refractive index of the transparent conductive oxide layer. 21. A flip-chip light emitting diode (LED) package structure, comprising: a package substrate; and a LED device, faced-down and flipped on the package substrate and electrically connected to the package substrate, wherein the LED device comprises: a device substrate; a first doped layer, formed on the device substrate; a light emitting layer, formed on the first doped layer; a second doped layer, formed on the light emitting layer, wherein the second doped layer and the first doped layer are comprised of a semiconductor material of a III-V group compound with different conductivity type; a strained-layer superlattice contact layer; a transparent conductive oxide layer as an ohmic contact layer, wherein the transparent conductive oxide layer is deposited on the strained-layer superlattice contact layer; a transparent insulating layer as a passivation layer, wherein the transparent insulating layer is deposited on transparent conductive oxide layer; a reflecting layer, deposited on the transparent insulating layer and a portion of the transparent conductive oxide layer; and two electrodes, formed on the reflecting layer and a portion of the first doped layer, respectively. 22. The flip-chip LED package structure of claim 21, wherein a thickness of the transparent conductive oxide layer is (2 m+1)λ/2n (m is 0 or a positive integer), wherein λ is a wavelength of a light emitted from the light emitting layer and n is a refractive index of the transparent conductive oxide layer. 23 The flip-chip LED package structure of claim 21, wherein a thickness of the transparent insulating layer is (2 m+1)λ/2k (m is 0 or a positive integer), wherein λ is a wavelength of a light emitted from the light emitting layer and k is a refractive index of the transparent insulating layer. 24. A light reflective structure for a light emitting diode (LED), comprising: a transparent conductive oxide layer deposited on a semiconductor layer; a transparent insulating layer deposited on the transparent conductive oxide layer; and a reflecting layer deposited on the transparent insulating layer. 25. The light reflective structure of claim 24, wherein a thickness of the transparent conductive oxide layer is (2 m+1)λ/2n (m is 0 or a positive integer), wherein λ is a wavelength of a light emitted from the light emitting layer and n is a refractive index of the transparent conductive oxide layer. 26 The LED device of claim 24, wherein a thickness of the transparent insulating layer is (2 m+1)λ/2k (m is 0 or a positive integer), wherein λ is a wavelength of a light emitted from the light emitting layer and k is a refractive index of the transparent insulating layer.

CROSS REFERENCE TO RELATED APPLICATIONS This application claims the priority benefit of Taiwan application serial no.92120195, filed on Jul. 24, 2003. BACKGROUND OF INVENTION 1. Field of the Invention The invention relates in general to a structure of a semiconductor light emitting device, and more particularly, to a structure of a light emitting diode (LED) device, to a package structure of a flip-chip LED device, and to a light reflective structure being applicable for a LED. 2. Related Art of the Invention In general, a light emitting diode (LED) constructed by an III-V semiconductor material can be provided as a wide bandgap light emitting device. The wavelength of the light emitted from the wide bandgap light emitting device ranges from infrared (IR) to ultraviolet (UV); therefore the entire spectrum of visible light is also covered. In recent years, due to the rapid development of the high illumination of the gallium nitride (GaN) LEDs having a blue/green light, the full-color LED display, white light LED and the LED for traffic signals are put into practice. Therefore, the application of a variety of LED also becomes more popular. In principle, a fundamental structure of a LED device includes an epitaxy layer of a P-type and a N-type III-V group compound and a light emitting layer in-between. The light emitting efficiency of the LED device is dependent on the internal quantum efficiency of the light emitting layer and the light extraction efficiency of the device. A method of increasing the internal quantum efficiency includes, for the most part, improving the quality of the light emitting layer and the design of the structure. The method of increasing the light extraction efficiency includes, for the most part, decreasing the light loss caused by the absorption of the light emitted from the light emitting layer due to the reflection of the light inside the LED device. In a conventional gallium nitride (GaN) LED device grown on the first substrate, such as sapphire, having an insulating property, since the positive and the negative electrodes of a gallium nitride (GaN) LED device are deposited on, in general, the same side of a first surface, and the positive electrode will screen out the emitted light from light emitting layer. Therefore, the packaging for a gallium nitride (GaN) LED normally uses the flip chip method. Thus, the emitted light will pass through the second surface. Moreover, a reflecting layer is formed on the topmost surface of GaN LED that faces the second substrate, in order to emit most of the emitted light towards the second surface of a GaN LED. Another advantage of using the flip-chip package process is, if a proper surface mount (so called surmount) substrate, for example, a silicon substrate is provided, the heat dissipation of the LED device is enhanced, especially under a high current operation. Accordingly, not only the light extraction efficiency is increased, the internal quantum efficiency of the light emitting layer will also be maintained. Moreover, in order to improve the electrical property of the LED device, a semi-transparent nickel (Ni)/gold (Au) ohmic contact layer is first formed on the epitaxy layer surface, and a thermal process is performed to form a desirable ohmic contact, followed by forming a reflecting layer thereon. However, since the absorption of light of the Ni/Au layer is high (the transparency of that is about 60% to about 70%), and due to the thermal process, the interface between the epitaxy layer and the Ni/Au layer becomes too rough to reflect light. Accordingly, the light reflective efficiency of the bottom of the flip-chip LEDs device will be reduced. SUMMARY OF INVENTION Accordingly, the present invention is to provide a light reflective structure, which is applicable for a LED device to enhance the extraction efficiency of light. Another object of the present invention is to provide a LED device having a light reflective structure of the present invention, wherein the extraction efficiency of light is enhanced. It is yet another object of the present invention to provide a flip-chip LED package structure having a light reflective structure of the present invention, wherein the extraction efficiency of light is enhanced. In order to achieve the above objects and other advantages of the present invention, a light reflective structure for a LED device is provided. The light reflective structure includes, for example but not limited to, a transparent conductive oxide layer deposited on a semiconductor layer, a transparent insulating layer deposited on the transparent conductive oxide layer, and a reflecting layer deposited on the transparent insulating layer. The transparent conductive oxide layer is provided as an ohmic contact layer for the semiconductor layer. The transparent insulating layer is provided as a passivation layer for the transparent conductive oxide layer. When the wavelength of the light emitted from the LED device is λ, and the refractive index of the transparent conductive oxide layer is n, the thickness of the transparent conductive oxide layer is preferably to be (2 m+1)λ/2n (m is 0 or an positive integer). When the refractive index of the transparent insulating layer is k, the thickness of the transparent insulating layer is preferably to be (2 m+1)λ/2k (m is 0 or an positive integer). Therefore, a constructive interference of the lights is achieved. In order to achieve the above objects and other advantages of the present invention, a light reflective structure applicable for a LED device is provided. The light reflective structure includes a transparent conductive oxide layer deposited on a semiconductor layer, and a reflecting layer deposited on the transparent conductive oxide layer. The transparent conductive oxide layer is provided as an ohmic contact layer for the semiconductor layer. When the wavelength of the light emitted from the LED device is λ, and the refractive index of the transparent conductive oxide layer is n, the thickness of the transparent conductive oxide layer is preferably to be (2 m+1)λ/2n (m is 0 or a positive integer). Therefore, a constructive interference of the lights is achieved. The LED device of the present invention includes a first substrate called device substrate, a first doped layer, a light emitting layer, a second doped layer, a transparent conductive oxide layer, a reflecting layer, and two electrodes. The first doped layer is deposited on the device substrate, the light emitting layer is deposited on the first doped layer, and the second doped layer is deposited on the light emitting layer. The second doped layer and the first doped layer are constructed from an III-V group compound of semiconductor material with different conductivity type. The transparent conductive oxide layer is deposited on the second doped layer, and is provided as an ohmic contact layer. The transparent insulating layer is deposited on the ohmic contact layer to serves as a passivation layer. The reflecting layer is deposited on the transparent insulating layer. The two electrodes are formed on the reflecting layer and the first doped layer, respectively. The LED device of the present invention includes a first substrate called device substrate, a first doped layer, a light emitting layer, a second doped layer, a transparent conductive oxide layer, a reflecting layer, and two electrodes. The first doped layer is deposited on the device substrate, the light emitting layer is deposited on the first doped layer, and the second doped layer is deposited on the light emitting layer. The second doped layer and the first doped layer are constructed from an III-V group compound of semiconductor material with different conductivity type. The transparent conductive oxide layer is deposited on the second doped layer, and is provided as an ohmic contact layer. The reflecting layer is deposited on the transparent conductive oxide layer. The two electrodes are formed on the reflecting layer and the first doped layer, respectively. The flip-chip LED package structure of the present invention includes a package substrate called second substrate or submount substrate and a LED structure on the first substrate, in which the LED is faced-down over the package substrate and is electrically connected to the package substrate. The LED includes a first substrate (device substrate), a first doped layer, a light emitting layer, a second doped layer, a transparent conductive oxide layer, a transparent insulating passivation layer, a reflecting layer, and two electrodes. The first doped layer is deposited on the first substrate, the light emitting layer is deposited on the first doped layer, and the second doped layer is deposited on the light emitting layer. The second doped layer and the first doped layer are constructed from an III-V group compound of semiconductor material with different conductivity type. The transparent conductive oxide layer is deposited on the second doped layer, and is provided as an ohmic contact layer. The transparent insulating layer is deposited on the ohmic contact layer to serves as a passivation layer. The reflecting layer is deposited on the transparent insulating layer. The two electrodes are deposited on the reflecting layer and the first doped layer, respectively. The flip-chip LED package structure of the present invention includes a package substrate called second substrate or submount substrate and a LED structure on the first substrate, in which the LED is faced-down over the package substrate and is electrically connected to the package substrate. The LED includes a first substrate (device substrate), a first doped layer, a light emitting layer, a second doped layer, a transparent conductive oxide layer, a reflecting layer, and two electrodes. The first doped layer is deposited on the first substrate, the light emitting layer is deposited on the first doped layer, and the second doped layer is deposited on the light emitting layer. The second doped layer and the first doped layer are constructed from an III-V group compound of semiconductor material with different conductivity type. The transparent conductive oxide layer is deposited on the second doped layer, and is provided as an ohmic contact layer. The reflecting layer is deposited on the transparent insulating layer. The two electrodes are deposited on the reflecting layer and the first doped layer, respectively. Accordingly, in the present invention, the material of the ohmic contact layer includes a transparent conductive metal oxide, and a thermal process for achieving a good ohmic contact is not required for the transparent conductive metal oxide. Therefore, the interface between the ohmic contact layer and the second doped layer is smooth, and thus the interface can be provided as a reflecting surface. Moreover, in the present invention, the absorption to visible light of the transparent conductive metal oxide can be reduced to less than 10% (for example, when the oxide is an indium tin oxide (ITO; therefore, the absorption of the ohmic contact layer to the LED device is reduced drastically. It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed. BRIEF DESCRIPTION OF DRAWINGS The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. FIG. 1 is a cross-sectional view illustrating a structure of a LED device and a enlarged view of a portion adjacent to a interface of the transparent conductive oxide layer of the LED device according to a preferred embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating another structure of a LED device. FIG. 3 is a cross-sectional view illustrating a flip-chip LED package structure achieved after a flip-chip package process of the LED device of FIG. 1 and FIG. 2. DETAILED DESCRIPTION The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. FIG. 1 is a cross-sectional view illustrating a structure of a LED device and a enlarged view of a portion adjacent to a interface of the transparent conductive oxide layer of the LED device according to a preferred embodiment of the present invention. Referring to FIG. 1, the LED device includes a device substrate 100, a N-type doped layer 110, a light emitting layer 120, a P-type doped layer 130, a strained-layer superlattice (SLS) contact layer 135, a transparent conductive oxide layer 140, a reflecting layer 150, and an anode 160 and a cathode 170. In FIG. 1, an active layer constructed by a N-type doped layer 110, a light emitting layer 120 and a P-type doped layer 130 is formed, for example but not limited to, by performing a series of epitaxy processes sequentially on the device substrate 100. Moreover, in the succeeding process, a portion of the N-type doped layer 110, a portion of the light emitting layer 120 and a portion of the P-type doped layer 130 are removed, for example but not limited to, by etching or by another method. Therefore, each of the layers 110, 120, 130 and 135 are patterned to form a plurality of isolated island structure (MESA). It is noticed that, in the isolated island structure above, a portion of the P-type doped layer 130 and SLS contact layer 135 over the cathode 170, the light emitting layer 120 and a portion of the N-type doped layer 110 are removed. The cathode 170 thus can be electrically connected with the N-type doped layer 110. Referring to FIG. 1, in the present embodiment, the transparent conductive oxide layer 140 is deposited on the SLS contact layer 135, while the reflecting layer 150 is deposited on the transparent conductive oxide layer 140 and the anode 160 is deposited on the reflecting layer 150. The device substrate 100 includes, for example but not limited to, a sapphire substrate. The materials of the N-type doped layer 110, light emitting layer 120, the P-type doped layer 130, and SLS contact layer 135 are comprised of a III-V group compound of semiconductor material, including but not limited to, a gallium nitride (GaN), a gallium phosphide (GaP) or a gallium phosphide arsenide (GaAsP). The light emitting layer 120 includes, for example but not limited to, a single or a multi quantum well structure, to enhance the light emitting efficiency. A material of the transparent conductive oxide layer 140 preferably includes an indium tin oxide (ITO), but also may include, for example but not limited to, such as ITO, CTO, IZO, ZnO:Al, ZnGa2O4, SnO2:Sb, Ga2O3:Sn, AgInO2:Sn, In2O3:Zn, CuAlO2, LaCuOS, NiO, CuGaO2, SrCu2O2, and so on or other transparent conductive material having similar properties. A material of the reflecting layer 150 includes, for example but not limited to, an aluminum (Al), a silver (Ag), Ni/Ag, Ni/Al, Mo/Ag, Mo/Al, Ti/Ag, Ti/Al, Nd/Al, Nd/Ag, Pd/Al, Pd/Ag, Cr/Al, Cr/Ag and materials of the anode 160 and the cathode 170 include, for example but not limited to, a bi-layer or tri-layer metal system, such as Cr/Au, Ti/Au, Cr/Pt/Au and Ti/Pt/Au. As shown in the enlarged view of FIG. 1, since the transparent conductive oxide layer 140 does not require a thermal process for increasing the ohm contact efficiency, the interface between the transparent conductive oxide layer 140 and the SLS contact layer 135 is smooth. A desirable reflecting effect is thereby achieved. Moreover, according to the theory of light interference, when the light emitting wavelength of the LED device is λ, and the refractive index of the transparent conductive oxide layer 140 is n, the thickness of the transparent conductive oxide layer 140 is preferably to be (2 m+1)λ/2n (m is 0 or an positive integer such as 1, 2, 3, etc.). Thus, the reflecting light from the interface between the transparent conductive oxide layer 140 and the reflecting layer 150, and the reflecting light from the interface of the SLS contact layer 135 and the transparent conductive oxide layer 140 can generate a constructive interference effect. FIG. 2 is a cross-sectional view illustrating another structure of a LED device. Referring to FIG. 2, the LED device includes a device substrate 200, a N-type doped layer 210, a light emitting layer 220, a P-type doped layer 230, a strained-layer superlattice (SLS) contact layer 235, a transparent conductive oxide layer 240, a transparent insulating passivation layer 245, a reflecting layer 250, and an anode 260 and a cathode 270. In FIG. 2, an active layer constructed by a N-type doped layer 210, a light emitting layer 220 and a P-type doped layer 230 is formed, for example but not limited to, by performing a series of epitaxy processes sequentially on the device substrate 200. Moreover, in the succeeding process, a portion of the N-type doped layer 210, a portion of the light emitting layer 220, a portion of the P-type doped layer 230 and a SLS contact layer 235 are removed, for example but not limited to, by etching or by another method. Therefore, each of the layers 210, 220, 230 and 235 are patterned to form a plurality of isolated island structure (MESA). It is noticed that, in the isolated island structure above, a portion of the P-type doped layer 230 and SLS contact layer 235 over the cathode 270, the light emitting layer 220 and a portion of the N-type doped layer 210 are removed. The cathode 270 thus can be electrically connected with the N-type doped layer 210. Referring to FIG. 2, in the present embodiment, the transparent conductive oxide layer 240 is deposited on the SLS contact layer 235, and the transparent insulating passivation layer 245 is deposited on the transparent conductive oxide layer 240 while the reflecting layer 250 is deposited on the transparent insulating passivation layer 245 and the anode 260 is deposited on the reflecting layer 250. The device substrate 200 includes, for example but not limited to, a sapphire substrate. The materials of the N-type doped layer 210, light emitting layer 220, the P-type doped layer 230, and SLS contact layer 235 are comprised of a III-V group compound of semiconductor material, including but not limited to, a gallium nitride (GaN), a gallium phosphide (GaP) or a gallium phosphide arsenide (GaAsP). The light emitting layer 220 includes, for example but not limited to, a single or a multi quantum well structure, to enhance the light emitting efficiency. A material of the transparent conductive oxide layer 140 preferably includes an indium tin oxide (ITO), but also may include, for example but not limited to, such as ITO, CTO, IZO, ZnO:Al, ZnGa2O4, SnO2:Sb, Ga2O3:Sn, AgInO2:Sn, In2O3:Zn, CuAlO2, LaCuOS, NiO, CuGaO2, SrCu2O2, and so on. or other transparent conductive material having similar properties. A material of the transparent insulating passivation layer 245 includes, for example but not limited to, a SiO2, SiNx, Al2O3, AlN, BeO, ZnO, and so on. A material of the reflecting layer 250 includes, for example but not limited to, an aluminum (Al), a silver (Ag), Ni/Ag, Ni/Al, Mo/Ag, Mo/Al, Ti/Ag, Ti/Al, Nd/Al, Nd/Ag, Pd/Al, Pd/Ag, Cr/Al, Cr/Ag and materials of the anode 260 and the cathode 270 include, for example but not limited to, a bi-layer or tri-layer metal system, such as Cr/Au, Ti/Au, Cr/Pt/Au and Ti/Pt/Au. As shown in the enlarged view of FIG. 2, since the transparent conductive oxide layer 240 does not require a thermal process for increasing the ohm contact efficiency, the interface between the transparent conductive oxide layer 240 and the SLS contact layer 235 is smooth. A desirable reflecting effect is thereby achieved. Moreover, according to the theory of light interference, when the light emitting wavelength of the LED device is λ, and the refractive index of the transparent conductive oxide layer 140 is n, the thickness of the transparent conductive oxide layer 240 is preferably to be (2 m+1)λ/2n (m is 0 or an positive integer such as 1, 2, 3, etc.). Moreover, according to the theory of light interference, when the light emitting wavelength of the LED device is λ, and the refractive index of the transparent insulating passivation layer 245 is k, the thickness of the transparent insulating passivation layer 245 is preferably to be (2 m+1)λ/2k (m is 0 or an positive integer such as 1, 2, 3, etc.). Thus, the reflecting light from the interface between the transparent insulating passivation layer 245 and the reflecting layer 250, and the reflecting light from the interface of the SLS contact layer 235 and the transparent conductive oxide layer 240 can generate a constructive interference effect. FIG. 3 is a cross-sectional view illustrating a flip-chip LED package structure obtained after the flip-chip packaging of the LED device of FIG. 1 and FIG. 2. Referring to FIG. 3, the LED device of FIG. 1 or FIG. 2 is flipped over a package substrate 300, the package substrate 300 includes, for example but not limited to, a silicon substrate. The LED device of FIG. 1 and the package substrate 300 are electrically connected via a bump 380 and a bump 390. The bump 380 is electrically connected with the anode 160 and the package substrate 300, and the bump 390 is electrically connected with the cathode 170 and the package substrate 300. Since the reflecting layer 150 is between the top layer of the FIG. 1 and the package substrate 300, and faces to the package substrate 200. Thus, the light emitted from the light emitting layer 120 is reflected by the multi-layer structures including the layer 135, layer 140, and layer 150 and emits through the device substrate 100. Similar concept is also suitable for a device consisting of a transparent insulating passivation layer, as shown in FIG. 2. Moreover, the device structure of the embodiments described above, for example, a LED device having a flip-chip package structure, is only an example for describing the present invention. The scope of the invention is not limited to the above embodiments. Moreover, the present invention can also be provided for all of the LED devices that are formed with an ohmic contact layer and a reflecting layer and are packaged by a process other than the flip-chip package process for increasing the light reflecting efficiency. In addition, although the present invention is described with a N-type doped layer being formed on the device substrate, and a P-type doped layer being formed on the light emitting layer and, the present invention is also applicable with the conductive type of the doped layers being exchanged. That is, a P-type doped layer is formed on the device substrate, and a N-type doped layer is formed on the light emitting layer. Therefore, the electrode formed on the reflecting layer is served as a cathode, and the electrode formed on the P-type doped layer is served as an anode. In accordance to the present invention, the material of the ohmic contact layer includes a transparent conductive metal oxide, wherein a thermal process for increasing the ohmic contact efficiency is not required for the transparent conductive metal oxide. Therefore, the interface between the ohmic contact layer and the SLS contact layer is smooth, and thus the interface can be provided as a reflecting surface. Moreover, in the present invention, the absorption to visible light of the transparent conductive metal oxide can be reduced to less than 10% (for example, when the oxide is a indium tin oxide (ITO); therefore, the absorption of the ohmic contact layer to the LED device is reduced drastically. It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.

<SOH> BACKGROUND OF INVENTION <EOH>1. Field of the Invention The invention relates in general to a structure of a semiconductor light emitting device, and more particularly, to a structure of a light emitting diode (LED) device, to a package structure of a flip-chip LED device, and to a light reflective structure being applicable for a LED. 2. Related Art of the Invention In general, a light emitting diode (LED) constructed by an III-V semiconductor material can be provided as a wide bandgap light emitting device. The wavelength of the light emitted from the wide bandgap light emitting device ranges from infrared (IR) to ultraviolet (UV); therefore the entire spectrum of visible light is also covered. In recent years, due to the rapid development of the high illumination of the gallium nitride (GaN) LEDs having a blue/green light, the full-color LED display, white light LED and the LED for traffic signals are put into practice. Therefore, the application of a variety of LED also becomes more popular. In principle, a fundamental structure of a LED device includes an epitaxy layer of a P-type and a N-type III-V group compound and a light emitting layer in-between. The light emitting efficiency of the LED device is dependent on the internal quantum efficiency of the light emitting layer and the light extraction efficiency of the device. A method of increasing the internal quantum efficiency includes, for the most part, improving the quality of the light emitting layer and the design of the structure. The method of increasing the light extraction efficiency includes, for the most part, decreasing the light loss caused by the absorption of the light emitted from the light emitting layer due to the reflection of the light inside the LED device. In a conventional gallium nitride (GaN) LED device grown on the first substrate, such as sapphire, having an insulating property, since the positive and the negative electrodes of a gallium nitride (GaN) LED device are deposited on, in general, the same side of a first surface, and the positive electrode will screen out the emitted light from light emitting layer. Therefore, the packaging for a gallium nitride (GaN) LED normally uses the flip chip method. Thus, the emitted light will pass through the second surface. Moreover, a reflecting layer is formed on the topmost surface of GaN LED that faces the second substrate, in order to emit most of the emitted light towards the second surface of a GaN LED. Another advantage of using the flip-chip package process is, if a proper surface mount (so called surmount) substrate, for example, a silicon substrate is provided, the heat dissipation of the LED device is enhanced, especially under a high current operation. Accordingly, not only the light extraction efficiency is increased, the internal quantum efficiency of the light emitting layer will also be maintained. Moreover, in order to improve the electrical property of the LED device, a semi-transparent nickel (Ni)/gold (Au) ohmic contact layer is first formed on the epitaxy layer surface, and a thermal process is performed to form a desirable ohmic contact, followed by forming a reflecting layer thereon. However, since the absorption of light of the Ni/Au layer is high (the transparency of that is about 60% to about 70%), and due to the thermal process, the interface between the epitaxy layer and the Ni/Au layer becomes too rough to reflect light. Accordingly, the light reflective efficiency of the bottom of the flip-chip LEDs device will be reduced.

<SOH> SUMMARY OF INVENTION <EOH>Accordingly, the present invention is to provide a light reflective structure, which is applicable for a LED device to enhance the extraction efficiency of light. Another object of the present invention is to provide a LED device having a light reflective structure of the present invention, wherein the extraction efficiency of light is enhanced. It is yet another object of the present invention to provide a flip-chip LED package structure having a light reflective structure of the present invention, wherein the extraction efficiency of light is enhanced. In order to achieve the above objects and other advantages of the present invention, a light reflective structure for a LED device is provided. The light reflective structure includes, for example but not limited to, a transparent conductive oxide layer deposited on a semiconductor layer, a transparent insulating layer deposited on the transparent conductive oxide layer, and a reflecting layer deposited on the transparent insulating layer. The transparent conductive oxide layer is provided as an ohmic contact layer for the semiconductor layer. The transparent insulating layer is provided as a passivation layer for the transparent conductive oxide layer. When the wavelength of the light emitted from the LED device is λ, and the refractive index of the transparent conductive oxide layer is n, the thickness of the transparent conductive oxide layer is preferably to be (2 m+1)λ/2n (m is 0 or an positive integer). When the refractive index of the transparent insulating layer is k, the thickness of the transparent insulating layer is preferably to be (2 m+1)λ/2k (m is 0 or an positive integer). Therefore, a constructive interference of the lights is achieved. In order to achieve the above objects and other advantages of the present invention, a light reflective structure applicable for a LED device is provided. The light reflective structure includes a transparent conductive oxide layer deposited on a semiconductor layer, and a reflecting layer deposited on the transparent conductive oxide layer. The transparent conductive oxide layer is provided as an ohmic contact layer for the semiconductor layer. When the wavelength of the light emitted from the LED device is λ, and the refractive index of the transparent conductive oxide layer is n, the thickness of the transparent conductive oxide layer is preferably to be (2 m+1)λ/2n (m is 0 or a positive integer). Therefore, a constructive interference of the lights is achieved. The LED device of the present invention includes a first substrate called device substrate, a first doped layer, a light emitting layer, a second doped layer, a transparent conductive oxide layer, a reflecting layer, and two electrodes. The first doped layer is deposited on the device substrate, the light emitting layer is deposited on the first doped layer, and the second doped layer is deposited on the light emitting layer. The second doped layer and the first doped layer are constructed from an III-V group compound of semiconductor material with different conductivity type. The transparent conductive oxide layer is deposited on the second doped layer, and is provided as an ohmic contact layer. The transparent insulating layer is deposited on the ohmic contact layer to serves as a passivation layer. The reflecting layer is deposited on the transparent insulating layer. The two electrodes are formed on the reflecting layer and the first doped layer, respectively. The LED device of the present invention includes a first substrate called device substrate, a first doped layer, a light emitting layer, a second doped layer, a transparent conductive oxide layer, a reflecting layer, and two electrodes. The first doped layer is deposited on the device substrate, the light emitting layer is deposited on the first doped layer, and the second doped layer is deposited on the light emitting layer. The second doped layer and the first doped layer are constructed from an III-V group compound of semiconductor material with different conductivity type. The transparent conductive oxide layer is deposited on the second doped layer, and is provided as an ohmic contact layer. The reflecting layer is deposited on the transparent conductive oxide layer. The two electrodes are formed on the reflecting layer and the first doped layer, respectively. The flip-chip LED package structure of the present invention includes a package substrate called second substrate or submount substrate and a LED structure on the first substrate, in which the LED is faced-down over the package substrate and is electrically connected to the package substrate. The LED includes a first substrate (device substrate), a first doped layer, a light emitting layer, a second doped layer, a transparent conductive oxide layer, a transparent insulating passivation layer, a reflecting layer, and two electrodes. The first doped layer is deposited on the first substrate, the light emitting layer is deposited on the first doped layer, and the second doped layer is deposited on the light emitting layer. The second doped layer and the first doped layer are constructed from an III-V group compound of semiconductor material with different conductivity type. The transparent conductive oxide layer is deposited on the second doped layer, and is provided as an ohmic contact layer. The transparent insulating layer is deposited on the ohmic contact layer to serves as a passivation layer. The reflecting layer is deposited on the transparent insulating layer. The two electrodes are deposited on the reflecting layer and the first doped layer, respectively. The flip-chip LED package structure of the present invention includes a package substrate called second substrate or submount substrate and a LED structure on the first substrate, in which the LED is faced-down over the package substrate and is electrically connected to the package substrate. The LED includes a first substrate (device substrate), a first doped layer, a light emitting layer, a second doped layer, a transparent conductive oxide layer, a reflecting layer, and two electrodes. The first doped layer is deposited on the first substrate, the light emitting layer is deposited on the first doped layer, and the second doped layer is deposited on the light emitting layer. The second doped layer and the first doped layer are constructed from an III-V group compound of semiconductor material with different conductivity type. The transparent conductive oxide layer is deposited on the second doped layer, and is provided as an ohmic contact layer. The reflecting layer is deposited on the transparent insulating layer. The two electrodes are deposited on the reflecting layer and the first doped layer, respectively. Accordingly, in the present invention, the material of the ohmic contact layer includes a transparent conductive metal oxide, and a thermal process for achieving a good ohmic contact is not required for the transparent conductive metal oxide. Therefore, the interface between the ohmic contact layer and the second doped layer is smooth, and thus the interface can be provided as a reflecting surface. Moreover, in the present invention, the absorption to visible light of the transparent conductive metal oxide can be reduced to less than 10% (for example, when the oxide is an indium tin oxide (ITO; therefore, the absorption of the ohmic contact layer to the LED device is reduced drastically. It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.

20040216

20050705

20050127

96584.0

QUINTO, KEVIN V

[LED DEVICE, FLIP-CHIP LED PACKAGE AND LIGHT REFLECTING STRUCTURE]

UNDISCOUNTED

ACCEPTED

ACCEPTED

CONTROLABLE RELEASE OF A VOLATILE SUBSTANCE

The present invention is directed to a device for releasing a controlled amount of a volatile substance into an environment while isolating the non-released amount of such a substance from the environment. The device includes a housing having an interior region, a volatile substance cartridge associated with the housing, wherein the cartridge can be replaced, or, alternatively, refilled with a desired fluid. A mechanism is provided for releasing a pre-determined amount of fluid from the housing, which is activated, as desired, by a user of the device.

1. A device for releasing a volatile substance into an environment comprising: a housing having an interior region, an outer surface, and an opening, wherein the housing includes a volatile substance cartridge for containing a fluid therewithin; means for orienting the device such that gravity forces the volatile substance toward the opening; and means for controllably releasing a predetermined amount of the volatile substance from the housing toward and onto an emanator, wherein fluid in the housing is substantially protected from exposure to the outside environment. 2. The device of claim 1, wherein the controlled release means has a first release and a second boost release of the volatile substance. 3. The device of claim 1, wherein the housing and the controlled release means isolate the volatile substance from the outside air and substantially prevent loss of the volatile substance until and after a desired release. 4. The device of claim 1, wherein the housing, controlled release means and emanator can operate with large swings in temperature and pressure of the outside environment. 5. The device according to claim 1 wherein the controlled release mean further comprises a rotating manually operable valve for releasing a predetermined amount of fluid on to an emanator to be utilized over time into the surrounding environment. 6. The device according to claim 1, further including means for protecting fluid in the reservoir from exposure to the outside environment. 7. The device according to claim 1 wherein the controlled release means comprises an electrically operated valve which releases predetermined amounts of the volatile substance to the emanator while isolating the remaining volatile substance in the housing from the outside environment such that there is substantially no loss of volatile substance until the valve is activated. 8. The device according to claim 1 wherein the device is used in automobiles, vehicles, airplanes, trains and other room spaces where large temperature and pressure swings exit. 9. The device according to claim 1 wherein the emanator is selected from the group consisting of porous plastic, cellulose pads, porous glass, ceramic pads, heated pads, piezo electric pads or ultrasonic pads, fans and combinations thereof. 10. The device according to claim 1 wherein the housing is constructed of a substantially rigid material having means for allowing air to fill the space when a predetermined amount of volatile substance controllably leaves the reservoir. 11. The device according to claim 1 wherein the housing comprises a flexible material 12. The device according to claim 1 wherein the volatile substance is selected from the group comprising fragrances, medicaments, insect repellents, cleaning chemicals and combination thereof. 13. The device according to claim 1 wherein the controller comprises a frame with a shuttle inside, the shuttle having a chamber with and a plurality of seals surrounding the shuttle, and a spring in contact with the shuttle for movement. 14. The device according to claim 1 wherein the shuttle has a chamber for delivering a predetermined dose of the volatile substance to a discharge hole within the frame. 15. The device according to claim 1 wherein the controller comprises a rotating pin. 16. The device according to claim 15 wherein the rotating pin includes mechanical stops. 17. The device according to claim 15 wherein the rotating pin has a spring return. 18. The device according to claim 1 wherein the emanator further comprises a surface to receive the fluid, the surface being an absorbent pad. 19. The device according to claim 1 wherein the emanator further comprises a surface to receive the fluid, the surface being a hard surface. 20. The device according to claim 1 wherein the emanator is associated with a heating element for increasing volatilization. 21. The device according to claim 1 further comprising means for increasing airflow adjacent the emanator. 22. The device according to claim 1, wherein the cartridge is replaceable 23. The device according to claim 1, wherein the cartridge is refillable. 24. A method of releasing a volatile substance into an outside environment comprising the steps of: storing a volatile substance in a reservoir; releasing a fixed dose of the volatile substance from the reservoir by a controller and the controller sealing the volatile substance from the outside environment until released; and collecting the fixed dose and vaporizing the fixed dose of the volatile substance into the outside environment by an emanator, the emanator positioned below the reservoir. 25. The method of claim 24, wherein the step of releasing comprises the step of activating the controller from a first position to a fluid releasing position while preventing loss of the volatile substance until and after a desired release. 26. The method of claim 24, wherein the step of activating is selected from the steps of manually or electronically activating.

BACKGROUND OF INVENTION 1. Field of the Invention The present invention generally relates to controlling the release of a volatile substance, more particularly, to controlling the release of a predetermined amount of a volatile substance of fluid and isolating the container of the volatile substance from the outside environment. 2. Background Art Prior art methods for delivering volatile substances from a container, for example a volatile substance such as a liquid, make use of absorbent material such as wicks. For example, one end of a wick is placed in a fluid to be dispensed, while the other end is exposed to the atmosphere. Capillary action will force liquid through the wick and to the exposed end of the wick. Once at the exposed end of the wick the liquid evaporates off of the end of the wick and into the surrounding atmosphere. Other prior art fluid delivery systems have relied upon various types of gravity driven mechanisms, allowing fluids to diffuse through a membrane under the force of gravity. For instance, Zembrodt, U.S. Pat. No. 4,948,047 shows a container for holding a liquid reservoir which is in contact with a membrane positioned in the bottom of the container. Under the force of gravity, the liquid diffuses through the membrane and volatilizes into the surrounding atmosphere from the exposed surface of the membrane. Likewise, Munteanu, U.S. Pat. No. 4,917,301, discloses a similar container for housing a liquid, with a membrane in the bottom of the container. Gravity again forces the liquid to diffuse through the membrane, from where it then evaporates into the surrounding atmosphere. Joshi et al. also describes gravity based devices in U.S. Pat. Nos. 5,932,204, 6,109,539 and 6,419,163 B1. Although these and other conventional controlled delivery systems have worked well they have failed to provide for both the controlled fixed amount of fluid to be released while isolating the rest of the fluid under large temperature swings or pressure swings occurring in some applications such as automobiles or airplanes and other temperature and pressure swing environments. Accordingly, such prior art devices have traditionally failed to isolate the volatile fluids from emanating under such high temperature or pressure swings, which, in turn, result in an excessive and rapid volatilization of fluids at a faster rate when no one is occupying the particular environment. Furthermore such devices have failed to provide a means for a user to selectively dispense only a fixed amount of fluid on the emanator and isolate the rest of fluid in the container from exposure to the atmosphere when the volatile substance needs to be protected from coming into contact with the atmosphere. SUMMARY OF INVENTION The present invention comprises a device for controllably releasing a fixed, predetermined amount of volatile substances (“fluid”) from a housing and isolating the rest of the fluid from the outside environment. The controlled substance release device comprises a housing, a volatile substance cartridge (for releasably holding a volatile fluid), and means for controllably releasing the substance from the housing on to an emanator pad. The housing further consists of an interior region, a release mechanism in the bottom end of the device, and means for orienting the device so that the force of gravity maintains the volatile substance over the releasing mechanism on the bottom end of the device. In one preferred embodiment, the device further includes a valve which functions as the controlled release means. The valve is positioned within the opening in the bottom of the device, and is in contact with the volatile substance. At the same time, at least a portion of the bottom surface of the valve is exposed to the atmosphere to allow the fixed amount of volatile substance to dispense from the valve on to an emanator pad. In addition, the device may further comprise means to re-supply the housing with additional amounts of volatile substance. Such re-supplying means may consist of an independent top end to the device, or an inlet port through which the volatile substance may be poured. Moreover, it is also contemplated that the volatile substance may be contained in a replaceable cartridge having means to cooperate with the housing during use of the device, to, in turn, allow the volatile substance to be released from the cartridge. In another preferred embodiment, the device further comprises a valve, and the housing is constructed of a material which is substantially permeable to ambient air, yet substantially impermeable to the volatile substance contained within the housing—in combination functioning as the controlled release means. The housing may consist of a series of microscopic pores, and may be fabricated from polypropylene, high density polyethylene, and polyethylene, to name a few. The housing allows ambient air to enter the interior region of the housing, thus allowing the volatile substance to dispense through an “on/off” valve when the valve is activated. At the same time, the housing prevents any loss of the volatile substance from the housing walls, through, for instance, a vent, thus preventing uncontrolled loss of the volatile substance, until such time that the valve is activated to dispense a fixed amount of fluid on to the associated emanator. It is likewise contemplated that the housing is substantially flexible yet substantially impermeable to the volatile substance. Once the valve is activated, the fixed amount of volatile substance is dispensed on to an emanator and the rest of the fluid is isolated from coming into contact with the emanator. In yet another preferred embodiment, the device further comprises a housing with an electrochemical gas generating cell as well as a fixed amount dispensing valve which acts to control the amount of the volatile substance from the housing. The cell emits gases into the interior region of the housing, thus allowing the release of the volatile substance through a valve and onto the emanator and, in turn, into the surrounding atmosphere. In another preferred embodiment, the device further comprises a dispensing valve in the housing, which is positioned below the volatile substance, and an emanator pad, which is positioned below the valve—thus comprising the controlled release means in this embodiment. The volatile substance drips through the valve when activated, where it falls onto the emanator pad. The emanator pad, in turn retains or absorbs the volatile substance, before the substance volatilizes from the surface of the emanator pad into the surrounding atmosphere. In still another preferred embodiment, the device further consists of a heating element associated with an emanator which serves to increase the evaporation rate, and thus the release rate of the volatile substance into the atmosphere. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a side cross sectional view of the controllable release device of the present invention in a pre-release, ready orientation; FIG. 1a is a side cross sectional view of the controllable release device shown in FIG. 1, in a fluid dispensing orientation; FIG. 2 is a side cross sectional view of another embodiment of the controllable release device of the present invention in a pre-release, ready orientation; FIG. 2a is a side cross sectional view of the controllable release device of FIG. 2, in a fluid dispensing orientation; FIG. 3 is a perspective view of a sub-assembly of a rack and pinion rotating a pin to activate a controllable release device of one embodiment of the present invention; FIG. 4 is a side cross sectional view of another preferred embodiment of a controllable release device of the present invention in a pre-release, ready orientation; FIG. 4a is a sectional view of a check valve shown in FIG. 4 and taken along lines 1-1; FIG. 4b is a side cross sectional view of the controllable release device of FIG. 4 in a fluid dispensing orientation; and FIG. 4c is a sectional view of a check valve shown in FIG. 4b. DETAILED DESCRIPTION The following detailed description is of the best currently contemplated mode of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims. Referring now to FIG. 1 of the drawings, shown is a drawing of a sectional side view of one embodiment of the present invention providing controlled release device 10. Controlled release device 10 is in a ready position 11 and the controlled release device 10 has a fragrance or fluid bottle 12 and a housing 14. The fragrance or fluid bottle 12 may be disposable or may be reusable. In FIG. 1, as in one embodiment of the present invention, device 10 includes spring 16 and chamber 18 disposed inside housing 14. Volatile substance, or fluid, 20 is inside fluid bottle/cartridge 12 when a shuttle 24 is in the ready position 11. When shuttle 24 is in the ready or dispensing position 13 (FIG. 1a), seals 22 protect fluid 20 from the outside environment or atmosphere 15 by closing off the environment or atmosphere 15 from fluid 20. Seals 22 close off atmosphere 15 by providing contact with shuttle 24 and housing 14. Shuttle 24 is positioned in the ready position 11 and dispensing position 13 by spring 16 which is in contact with shuttle 24. Spring 16 provides the ready position 11 when in a substantially uncompressed state 17. Conversely, spring 16 provides the dispensing position 13 when in a substantially compressed state 34 (FIG. 1a). Controller 19 provides the force 30 and timing to compress spring 16. As will be understood, the controller may comprise mechanical actuation by a user, or, an electromechanical switch for activation. Other conventional controlling/activating means are likewise contemplated for use. Referring to FIG. 1a, as in one embodiment of the present invention, shown is controlled release device 10 in dispensing position 13 with spring 16 in a substantially compressed state. Force 30 causes chamber 18 to line up with discharge hole 26. Emanator 28 is provided under the discharge hole 26. When chamber 18 lines up with discharge hole 26, fluid 20 is allowed to exit 32 housing 14 and collect on emanator 28. Vapors 36 leave fragrance 20 and fill the environment or atmosphere 15. Emanator 28 has an emanator surface 29. Controlled release device 10 can be activated by control 19 to fill the environment or atmosphere 15 with fluid 20 (such as a volatile fragrant fluid) for a certain period of time, and may be activated manually when more fragrance or fluid 20 is desired. For example, in a cabin of an automobile, the controller 19 may be a driver who can place controlled release device 10 in dispensing position 13 when, for example, the driver first enters the automobile. The driver may move shuttle 24 into dispensing position 13 once, or a multiple of times as desired. Fragrance or fluid 20 will be in the environment or atmosphere 15 for a period of time and may be boosted with a second, or subsequent activations by pushing the controller 19 when desired. Again, as shown in FIG. 1a, emanator surface 29 can be an absorbent pad or a simple hard surface, amongst others. Also the emanator surface can be heated to promote fragrance or fluid evaporation 31. Further emanator surface 29 may be placed in the airflow of a fan or a car vent or other such acceleration and distribution means. Referring to FIG. 2, according to another embodiment of the present invention, shown are drawings of one embodiment of the present invention providing controlled release device 40. Controlled release device 40 is shown in the ready position 42. Also shown is a fragrance or fluid bottle/cartridge 48 and a housing 50. The fragrance or fluid bottle/cartridge 48 may be disposable or may be reusable. When the bottle is disposable, it is contemplated that a replacement bottle/cartridge (filled with fluid) be substituted in its place. Release and replacement of the cartridge can be accomplished by any number of conventional means such as threaded releasable securement to the housing, snap-fit, biasing means, ratched mechanisms, etc. Alternatively, the cartridge may include a sealable aperture for enabling re-filling with additional fluid. Chamber 52 is disposed inside housing 50. A dosage 53 of fluid 54 is released from cartridge 48 and into chamber 52, which is formed in a cup-like shape in rotating pin 56. Rotating pin 56 is shown in the ready position 42, in FIG. 2, when cup-like chamber 52 aligns with opening 52′ of cartridge 48. When rotating pin 56 is in the ready position 42, seals 58 protect fragrance/fluid 54 from an outside environment or atmosphere 60 by closing off the environment or atmosphere 60 from fragrance 54. Seals 58 close off atmosphere 60 by providing contact with the rotating pin 56 and housing 50. Rotating pin 56 is positioned in the ready position 42 and dispensing position 62 (see FIG. 2a) by controller 64. Controller 64 provides the ready position 42 and may be rotated 180 degrees (with mechanical stops, if desired) thereby moving to dispensing position 62. Also, controller 64 may provide the ready position 42 and dispensing position 62 by using a spring return mechanism, among other types of return means. Also shown in FIG. 2 is optional gas generating cell 60′ which can assist in gravitational displacement of fluid. Controlled release device 40 is shown in FIG. 2a in a dispensing position 46. As can be seen, chamber 52 is lined up with discharge hole 66 of housing 50. Dosage 53 passes from chamber 52 through discharge hole 66 to emanator 68. Emanator 68 is provided under discharge hole 66. When chamber 52 lines up with discharge hole 66, fragrance 20 is allowed to exit 72 housing 50 and collect on emanator 68. Vapors 76 leave fragrance 54 and fill the environment or atmosphere 60. Referring to FIG. 3, shown is another preferred embodiment of a rotating mechanism which can be used in the present invention. The rotating mechanism includes rotating pin 80 by way of a rack 82 and pinion 84. Further shown is return spring 86 and fragrance dose chamber 88. Rotating pin 80 rotates 91 to dump a dosage 90 when the rack 82 is pushed 92. Referring to FIG. 4, according to another embodiment of the present invention, shown is controlled release device 100. Furthermore, as can be seen, the controlled release device is in a ready potion 108. Fluid reservoir 102, with fluid 104 inside includes vent 101. A dispensing chamber inlet valve 106 is below the fluid reservoir 102. The ready position 108 provides a dispensing chamber or bubble 110 filled with fluid 104. Dispensing chamber 110 is generally made of a flexible material. Activation force 112 is placed on the dispensing chamber 110. Discharge valve 114 is positioned below dispensing chamber 110 and above fluid outlet 118. Emanator 120 is positioned below the fluid outlet. Both the dispensing chamber inlet check valve 106 and the discharge valve 114 may be one-way check valves. Referring to FIG. 4a, shown is an exploded cross sectional view of the discharge valve 114. Discharge valve 114 is in a closed state 122 with ball 124 providing a seal force 125 from an un-compressed spring 126. Referring to FIG. 4b as in one embodiment of the present invention, provided is controlled release device 100 in a dispensing position 130. Dispensing chamber inlet check valve 106 is closed and discharge valve 114 is open. Dispensing chamber 110 is collapsed 132 by activation force (squeezing) causing fluid 104 to be forced out discharge valve 114 and onto emanator or evaporation surface 120. Referring to FIG. 4c is an exploded cross sectional view of the discharge valve 114. Discharge valve 114 is in an open state 134 with ball 124 allowing fluid 104 to pass with a compressed spring 136. As can be seen in FIGS. 4 and 4b, a means for providing a predetermined dose 140 by using a flexible bubble or dispensing chamber 110 and two-one way check valves 106 and 114 is disclosed. With dispensing chamber 110 full, compression forces are applied and fluid 104 is forced through the discharge valve 114 and the outlet 118 and onto the emanator 120. When the dispensing chamber 110 is compressed, the inlet valve or dispensing chamber inlet valve 106 is forced closed to prevent fluid 104 from moving back into the fluid reservoir 102. When dispensing chamber 110 is released, bubble 110 expands back toward its original shape prior to the application of the compression forces. At this time the outlet valve 114 is shut preventing air from being sucked into bubble 110. As bubble 110 expands it draws fluid in through inlet valve 106 from reservoir 102 so that bubble 110 is full and ready for another dose 140. As fluid 104 moves from the reservoir 102 into bubble 110, the volume of the reservoir 102 is replaced by air entering vent 101. It should be understood, of course, that the foregoing relates to preferred embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.

<SOH> BACKGROUND OF INVENTION <EOH>1. Field of the Invention The present invention generally relates to controlling the release of a volatile substance, more particularly, to controlling the release of a predetermined amount of a volatile substance of fluid and isolating the container of the volatile substance from the outside environment. 2. Background Art Prior art methods for delivering volatile substances from a container, for example a volatile substance such as a liquid, make use of absorbent material such as wicks. For example, one end of a wick is placed in a fluid to be dispensed, while the other end is exposed to the atmosphere. Capillary action will force liquid through the wick and to the exposed end of the wick. Once at the exposed end of the wick the liquid evaporates off of the end of the wick and into the surrounding atmosphere. Other prior art fluid delivery systems have relied upon various types of gravity driven mechanisms, allowing fluids to diffuse through a membrane under the force of gravity. For instance, Zembrodt, U.S. Pat. No. 4,948,047 shows a container for holding a liquid reservoir which is in contact with a membrane positioned in the bottom of the container. Under the force of gravity, the liquid diffuses through the membrane and volatilizes into the surrounding atmosphere from the exposed surface of the membrane. Likewise, Munteanu, U.S. Pat. No. 4,917,301, discloses a similar container for housing a liquid, with a membrane in the bottom of the container. Gravity again forces the liquid to diffuse through the membrane, from where it then evaporates into the surrounding atmosphere. Joshi et al. also describes gravity based devices in U.S. Pat. Nos. 5,932,204, 6,109,539 and 6,419,163 B1. Although these and other conventional controlled delivery systems have worked well they have failed to provide for both the controlled fixed amount of fluid to be released while isolating the rest of the fluid under large temperature swings or pressure swings occurring in some applications such as automobiles or airplanes and other temperature and pressure swing environments. Accordingly, such prior art devices have traditionally failed to isolate the volatile fluids from emanating under such high temperature or pressure swings, which, in turn, result in an excessive and rapid volatilization of fluids at a faster rate when no one is occupying the particular environment. Furthermore such devices have failed to provide a means for a user to selectively dispense only a fixed amount of fluid on the emanator and isolate the rest of fluid in the container from exposure to the atmosphere when the volatile substance needs to be protected from coming into contact with the atmosphere.

<SOH> SUMMARY OF INVENTION <EOH>The present invention comprises a device for controllably releasing a fixed, predetermined amount of volatile substances (“fluid”) from a housing and isolating the rest of the fluid from the outside environment. The controlled substance release device comprises a housing, a volatile substance cartridge (for releasably holding a volatile fluid), and means for controllably releasing the substance from the housing on to an emanator pad. The housing further consists of an interior region, a release mechanism in the bottom end of the device, and means for orienting the device so that the force of gravity maintains the volatile substance over the releasing mechanism on the bottom end of the device. In one preferred embodiment, the device further includes a valve which functions as the controlled release means. The valve is positioned within the opening in the bottom of the device, and is in contact with the volatile substance. At the same time, at least a portion of the bottom surface of the valve is exposed to the atmosphere to allow the fixed amount of volatile substance to dispense from the valve on to an emanator pad. In addition, the device may further comprise means to re-supply the housing with additional amounts of volatile substance. Such re-supplying means may consist of an independent top end to the device, or an inlet port through which the volatile substance may be poured. Moreover, it is also contemplated that the volatile substance may be contained in a replaceable cartridge having means to cooperate with the housing during use of the device, to, in turn, allow the volatile substance to be released from the cartridge. In another preferred embodiment, the device further comprises a valve, and the housing is constructed of a material which is substantially permeable to ambient air, yet substantially impermeable to the volatile substance contained within the housing—in combination functioning as the controlled release means. The housing may consist of a series of microscopic pores, and may be fabricated from polypropylene, high density polyethylene, and polyethylene, to name a few. The housing allows ambient air to enter the interior region of the housing, thus allowing the volatile substance to dispense through an “on/off” valve when the valve is activated. At the same time, the housing prevents any loss of the volatile substance from the housing walls, through, for instance, a vent, thus preventing uncontrolled loss of the volatile substance, until such time that the valve is activated to dispense a fixed amount of fluid on to the associated emanator. It is likewise contemplated that the housing is substantially flexible yet substantially impermeable to the volatile substance. Once the valve is activated, the fixed amount of volatile substance is dispensed on to an emanator and the rest of the fluid is isolated from coming into contact with the emanator. In yet another preferred embodiment, the device further comprises a housing with an electrochemical gas generating cell as well as a fixed amount dispensing valve which acts to control the amount of the volatile substance from the housing. The cell emits gases into the interior region of the housing, thus allowing the release of the volatile substance through a valve and onto the emanator and, in turn, into the surrounding atmosphere. In another preferred embodiment, the device further comprises a dispensing valve in the housing, which is positioned below the volatile substance, and an emanator pad, which is positioned below the valve—thus comprising the controlled release means in this embodiment. The volatile substance drips through the valve when activated, where it falls onto the emanator pad. The emanator pad, in turn retains or absorbs the volatile substance, before the substance volatilizes from the surface of the emanator pad into the surrounding atmosphere. In still another preferred embodiment, the device further consists of a heating element associated with an emanator which serves to increase the evaporation rate, and thus the release rate of the volatile substance into the atmosphere.

20040219

20061212

20050825

63694.0

PAIK, SANG YEOP

CONTROLABLE RELEASE OF A VOLATILE SUBSTANCE

SMALL

ACCEPTED

ACCEPTED

Methods and Apparatus for Generating Strongly-Ionized Plasmas with Ionizational Instabilities

Methods and apparatus for generating strongly-ionized plasmas are disclosed. A strongly-ionized plasma generator according to one embodiment includes a chamber for confining a feed gas. An anode and a cathode assembly are positioned inside the chamber. A pulsed power supply is electrically connected between the anode and the cathode assembly. The pulsed power supply generates a multi-stage voltage pulse that includes a low-power stage with a first peak voltage having a magnitude and a rise time that is sufficient to generate a weakly-ionized plasma from the feed gas. The multi-stage voltage pulse also includes a transient stage with a second peak voltage having a magnitude and a rise time that is sufficient to shift an electron energy distribution in the weakly-ionized plasma to higher energies that increase an ionization rate which results in a rapid increase in electron density and a formation of a strongly-ionized plasma.

1. A strongly-ionized plasma generator comprising: a) a chamber for confining a feed gas; b) an anode that is positioned inside the chamber; c) a cathode assembly that is positioned adjacent to the anode inside the chamber; and d) a pulsed power supply having an output that is electrically connected between the anode and the cathode assembly, the pulsed power supply generating at the output a multi-stage voltage pulse comprising: a low-power stage including a first peak voltage having a magnitude and a rise time that is sufficient to generate a weakly-ionized plasma from the feed gas; and a transient stage including a second peak voltage having a magnitude and a rise time that is sufficient to shift an electron energy distribution in the weakly-ionized plasma to higher energies that increase an ionization rate which results in a rapid increase in electron density and a formation of a strongly-ionized plasma. 2. The plasma generator of claim 1 further comprising a magnet that generates a magnetic field proximate to the cathode assembly. 3. The plasma generator of claim 2 wherein the magnet is movable. 4. The plasma generator of claim 2 wherein the magnetic field generated by the magnet confines the weakly-ionized and strongly ionized plasmas proximate to the cathode assembly. 5. The plasma generator of claim 2 wherein the magnetic field generated by the magnet and an electric field generated by the multi-stage voltage pulse induces an electron Hall current that raises the temperature of the electrons in the weakly-ionized plasma to a temperature that enhances the rapid increase in electron density and the formation of the strongly-ionized plasma. 6. The plasma generator of claim 1 wherein the feed gas comprises at least one of excited and metastable atoms. 7. The plasma generator of claim 1 wherein the magnitude of the first peak voltage is less than 1,000V. 8. The plasma generator of claim 1 wherein the pulsed power supply provides enough energy for the electron energy distribution in the weakly-ionized plasma to continuously shift to higher energies until the strongly ionized plasma is formed. 9. The plasma generator of claim 1 further comprising an energy storage device that is electrically coupled to the cathode assembly, the energy storage device discharging energy into the weakly-ionized plasma to enhance the rapid increase in electron density and the formation of the strongly-ionized plasma. 10. The plasma generator of claim 1 wherein the weakly-ionized plasma has a discharge current density that is less than about 0.5 A/cm2 and a power density that is less than about 250 W/cm2. 11. The plasma generator of claim 1 wherein the pulsed power supply generates the transient stage of the multi-stage pulse at a time that is at least 150 μsec after the generation of the weakly-ionized plasma. 12. The plasma generator of claim 1 wherein the rise time of the second peak voltage in the transient stage is greater than about 0.5V/μsec. 13. The plasma generator of claim 1 wherein the magnitude of the second peak voltage is less than about 1,000V over the first peak voltage. 14. The plasma generator of claim 1 wherein the second peak voltage in the transient stage forms ionizational instabilities in the weakly-ionized plasma. 15. The plasma generator of claim 1 wherein the transient stage generates diocotron oscillations in the weakly-ionized plasma. 16. The plasma generator of claim 1 wherein a discharge current density of the strongly-ionized plasma is greater than about 0.5 A/cm2. 17. The plasma generator of claim 1 wherein the power density of the strongly-ionized plasma is greater than 250 W/cm2. 18. The plasma generator of claim 1 wherein the multi-stage voltage pulse further comprises a high-power stage following the transient stage, the high-power stage having a voltage that is sufficient to sustain the strongly-ionized plasma. 19. The plasma generator of claim 18 wherein the voltage in the high-power stage comprises a relatively constant average voltage. 20. The plasma generator of claim 18 wherein a lifetime of the strongly-ionized plasma is greater than about 200 μsec. 21. A method of generating a strongly-ionized plasma, the method comprising: a) supplying feed gas proximate to an anode and a cathode assembly; b) generating a weakly-ionized plasma by applying a first voltage between the anode and the cathode assembly, the first voltage having a magnitude and a rise time that is sufficient to ignite the feed gas; and c) generating a strongly-ionized plasma from the weakly-ionized plasma by applying a second voltage between the anode and the cathode assembly, the second voltage having a magnitude and a rise time that is sufficient to shift an electron energy distribution in the weakly-ionized plasma to higher energies that increase an ionization rate which results in a rapid increase in electron density and a formation of the strongly-ionized plasma. 22. The method of claim 21 further comprising applying a magnetic field proximate to the cathode assembly. 23. The method of claim 22 further comprising moving the magnetic field. 24. The method of claim 22 further comprising generating an electron Hall current from an electric field generated by the second voltage and from the magnetic field, the electron Hall current raising the temperature of the electrons in the weakly-ionized plasma to a temperature that enhances the increase in electron density and the form ation of the strongly-ionized plasma. 25. The method of claim 21 wherein the first and the second voltages comprise a multi-stage voltage pulse. 26. The method of claim 21 further comprising applying a third voltage between the anode and the cathode assembly that sustains the strongly-ionized plasma. 27. The method of claim 26 wherein an average value of the third voltage applied between the anode and the cathode assembly is relatively constant. 28. The method of claim 21 wherein a lifetime of the strongly-ionized plasma is greater than 200 μsec. 29. The method of claim 21 wherein the weakly-ionized plasma is in a steady state condition before the application of the second voltage. 30. The method of claim 21 wherein the weakly-ionized plasma is in a quasi-steady state condition before the application of the second voltage. 31. The method of claim 21 further comprising discharging energy from an energy storage device into the weakly-ionized plasma to enhance the rapid increase in electron density and the formation of a strongly-ionized plasma. 32. The method of claim 21 wherein the magnitude and the rise time of the second voltage are sufficient to generate ionizational instabilities in the weakly-ionized plasma that enhance the ionization rate resulting in a rapid increase in electron density and the formation of the strongly-ionized plasma. 33. The method of claim 32 wherein the ionizational instabilities comprise diocotron instabilities. 34. The method of claim 21 wherein the magnitude of the first voltage is less than 1,000V. 35. The method of claim 21 wherein the rise time of the second voltage applied between the anode and the cathode assembly is greater than about 0.5V/μsec. 36. The method of claim 21 wherein the magnitude of the second voltage is less than about 1,000V over the first voltage. 37. The method of claim 21 wherein the weakly-ionized plasma has a discharge current density that is less than about 0.5 A/cm2 and a power density that is less than about 250 W/cm2. 38. A method of generating a strongly-ionized plasma, the method comprising: a) supplying feed gas proximate to an anode and a cathode assembly; and b) applying a voltage pulse between the anode and the cathode assembly, the voltage pulse comprising: a first peak voltage having a magnitude and a rise time that is sufficient to ignite an initial plasma from the feed gas; and a second peak voltage having a magnitude and a rise time that is sufficient to shift an electron energy distribution in the initial plasma to higher energies that increase an ionization rate resulting in a rapid increase in electron density and a formation of the strongly-ionized plasma that is sustained for greater than 200 μsec. 39. The method of claim 38 further comprising applying a magnetic field proximate to the cathode assembly. 40. The method of claim 39 further comprising moving the magnetic field. 41. The method of claim 39 further comprising generating an electron Hall current from an electric field generated by the voltage pulse and from the magnetic field, the electron Hall current raising the temperature of the electrons in the initial plasma to a temperature that enhances the rapid increase in electron density and the formation of the strongly-ionized plasma. 42. The method of claim 38 wherein the voltage pulse further comprises a substantially constant voltage that sustains the strongly-ionized plasma. 43. The method of claim 38 wherein a duration of the voltage pulse is greater than 200 μsec. 44. The method of claim 38 wherein the magnitude of the first peak voltage is less than 1,000V. 45. The method of claim 38 wherein the magnitude of the second peak voltage is less than about 1,000V over the first peak voltage. 46. The method of claim 38 wherein the second peak voltage has a magnitude and a rise time that are sufficient to generate ionizational instabilities that enhance the ionization rate resulting in the rapid increase in electron density and the formation of the strongly-ionized plasma. 47. An apparatus for generating a strongly-ionized plasma, the apparatus comprising: a) means for supplying feed gas proximate to an anode and a cathode assembly; b) means for generating a weakly-ionized plasma from the feed gas; c) means for shifting an electron energy distribution in the weakly-ionized plasma to higher energies that increase an ionization rate which results in a rapid increase in electron density and a formation of the strongly-ionized plasma from the weakly-ionized plasma; and d) means for sustaining the strongly-ionized plasma for greater than 200 μsec.

BACKGROUND OF INVENTION A plasma can be created in a chamber by igniting a direct current (DC) electrical discharge between two electrodes in the presence of a feed gas. The electrical discharge generates electrons in the feed gas that ionize atoms thereby creating the plasma. The electrons in the plasma provide a path for an electric current to pass through the plasma. The energy supplied to the plasma must be relatively high for applications, such as magnetron plasma sputtering. Applying high electrical currents through a plasma can result in overheating the electrodes as well as overheating the work piece in the chamber. Complex cooling mechanisms can be used to cool the electrodes and the work piece. However, the cooling can cause temperature gradients in the chamber. These temperature gradients can cause non-uniformities in the plasma density which can cause non-uniform plasma process. Temperature gradients can be reduced by pulsing DC power to the electrodes. Pulsing the DC power can allow the use of lower average power. This results in a lower temperature plasma process. However, pulsed DC power systems are prone to arcing at plasma ignition and plasma termination, especially when working with high-power pulses. Arcing can result in the release of undesirable particles in the chamber that can contaminate the work piece. Plasma density in known plasma systems is typically increased by increasing the electrode voltage. The increased electrode voltage increases the discharge current and thus the plasma density. However, the electrode voltage is limited in many applications because high electrode voltages can effect the properties of films being deposited or etched. In addition, high electrode voltages can also cause arcing which can damage the electrode and contaminate the work piece. BRIEF DESCRIPTION OF DRAWINGS This invention is described with particularity in the detailed description and claims. The above and further advantages of this invention may be better understood by referring to the following description in conjunction with the accompanying drawings, in which like numerals indicate like structural elements and features in various figures. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. FIG. 1 illustrates a cross-sectional view of a plasma sputtering apparatus having a pulsed direct current (DC) power supply according to one embodiment of the invention. FIG. 2 is measured data of discharge voltage as a function of discharge current for a prior art low-current plasma and a high-current plasma according to the present invention. FIG. 3 is measured data of a particular voltage pulse generated by the pulsed power supply of FIG. 1 operating in a low-power voltage mode. FIG. 4 is measured data of a multi-stage voltage pulse that is generated by the pulsed power supply of FIG. 1 that creates a strongly-ionized plasma according to the present invention. FIG. 5A-FIG. 5C are measured data of other illustrative multi-stage voltage pulses generated by the pulsed power supply of FIG. 1. FIG. 6A and FIG. 6B are measured data of multi-stage voltage pulses generated by the pulsed power supply of FIG. 1 that illustrate the effect of pulse duration in the transient stage of the pulse on the plasma discharge current. FIG. 7A and FIG. 7B are measured data of multi-stage voltage pulses generated by the pulsed power supply of FIG. 1 that show the effect of the pulsed power supply operating mode on the plasma discharge current. FIG. 8 is measured data for an exemplary single-stage voltage pulse generated by the pulsed power supply of FIG. 1 that produces a high-density plasma according to the invention that is useful for high-deposition rate sputtering. FIG. 9 illustrates a cross-sectional view of a plasma sputtering apparatus having a pulsed direct current (DC) power supply according to another embodiment of the invention. FIG. 10 illustrates a schematic diagram of a pulsed power supply that can generate multi-step voltage pulses according to the present invention. FIG. 11 illustrates a schematic diagram of a pulsed power supply having a magnetic compression network for supplying high-power pulses. FIG. 12 illustrates a schematic diagram of a pulsed power supply having a Blumlein generator for supplying high-power pulses. FIG. 13 illustrates a schematic diagram of a pulsed power supply having a pulse cascade generator for supplying high-power pulses. DETAILED DESCRIPTION FIG. 1 illustrates a cross-sectional view of a plasma sputtering apparatus 100 having a pulsed direct current (DC) power supply 102 according to one embodiment of the invention. The plasma sputtering apparatus 100 includes a vacuum chamber 104 for containing a plasma. The vacuum chamber 104 can be coupled to ground 105. The vacuum chamber 104 is positioned in fluid communication with a vacuum pump 106 that is used to evacuate the vacuum chamber 104 to high vacuum. The pressure inside the vacuum chamber 104 is generally less than 10−1 Torr for most plasma operating conditions. A process or feed gas 108 is introduced into the vacuum chamber 104 through a gas inlet 112 from a feed gas source 110, such as an argon gas source. The flow of the feed gas is controlled by a valve 114. In some embodiments, the gas source is an excited atom or metastable atom source. The plasma sputtering apparatus 100 also includes a cathode assembly 116. The cathode assembly 116 shown in FIG. 1 is formed in the shape of a circular disk, but can be formed in other shapes. In some embodiments, the cathode assembly 116 includes a target 118 for sputtering. The cathode assembly 116 is electrically connected to a first terminal 120 of the pulsed power supply 102 with an electrical transmission line 122. A ring-shaped anode 124 is positioned in the vacuum chamber 104 proximate to the cathode assembly 116. The anode 124 is electrically connected to ground 105. A second terminal 125 of the pulsed power supply 102 is also electrically connected to ground 105. In other embodiments, the anode 124 is electrically connected to the second terminal 125 of the pulsed power supply 102 which is not at ground potential. A housing 126 surrounds the cathode assembly 116. The anode 124 can be integrated with or electrically connected to the housing 126. The outer edge 127 of the cathode assembly 116 is electrically isolated from the housing 126 insulators 128. The gap 129 between the outer edge 127 of the cathode assembly 116 and the housing 126 can be an air gap or can include a dielectric material. In some embodiments, the plasma sputtering apparatus 100 includes a magnet assembly 130 that generates a etic field 132 proximate to the target 118. The magnetic field 132 is less parallel to the surface of the cathode assembly 116 at the poles of the magnets in the magnet assembly 130 and more parallel to the surface of the cathode assembly 116 in the region 134 between the poles of the magnets in the magnetic assembly 130. The magnetic field 132 is shaped to trap and concentrate secondary electrons emitted from the target 118 that are proximate to the target surface 133. The magnet assembly can consist of rotating magnets. The magnetic field 132 increases the density of electrons and therefore, increases the plasma density in the region 134 that is proximate to the target surface 133. The magnetic field 132 can also induce an electron Hall current 135 that is formed by the crossed electric and magnetic fields. The strength of the electron Hall current 135 depends, at least in part, on the density of the plasma and the strength of the crossed electric and magnetic fields. The plasma sputtering apparatus 100 also includes a substrate support 136 that holds a substrate 138 or other work piece for plasma processing. In some embodiments, the substrate support 136 is biased with a RF field. In these embodiments, the substrate support 136 is electrically connected to an output 140 of a RF power supply 142 with an electrical transmission line 144. A matching network (not shown) may be used to coupled the RF power supply 142 to the substrate support 136. In some embodiments, a temperature controller 148 is thermally coupled to the substrate support 136. The temperature controller 148 regulates the temperature of the substrate 138. In some embodiments, the plasma sputtering apparatus 100 includes an energy storage device 147 that provides a source of energy that can be controllably released into the plasma. The energy storage device 147 is electrically coupled to the cathode assembly 116. In one embodiment, the energy storage device 147 includes a capacitor bank. In operation, the vacuum pump 106 evacuates the chamber 104 to the desired operating pressure. The feed gas source 110 injects feed gas 108 into the chamber 104 through the gas inlet 112. The pulsed power supply 102 applies voltage pulses to the cathode assembly 116 that cause an electric field 149 to develop between the target 118 and the anode 124. The magnitude, duration and rise time of the initial voltage pulse are chosen such that the resulting electric field 149 ionizes the feed gas 108, thus igniting the plasma in the chamber 104. In one embodiment, ignition of the plasma is enhanced by one or more methods described in co-pending U.S. patent application Ser. No. 10/065,277, entitled High-Power Pulsed Magnetron Sputtering, and co-pending U.S. patent application Ser. No. 10/065,629, entitled Methods and Apparatus for Generating High-Density Plasma which are assigned to the present assignee. The entire disclosures of U.S. patent application Ser. No. 10/065,277 and U.S. patent application Ser. No. 10/065,629 are incorporated herein by reference. U.S. patent application Ser. No. 10/065,629 describes a method of accelerating the ignition of the plasma by increasing the feed gas pressure for a short period of time and/or flowing feed gas directly through a gap between an anode and a cathode assembly. In addition, U.S. patent application Ser. No. 10/065,277 describes a method of using pre-ionization electrodes to accelerate the ignition of the plasma. The characteristics of the voltage pulses generated by the pulsed power supply 102 and the resulting plasmas are discussed in connection with the following figures. The pulsed power supply 102 can include circuitry that minimizes or eliminates the probability of arcing in the chamber 104. Arcing is generally undesirable because it can damage the anode 124 and cathode assembly 116 and can contaminate the wafer or work piece being processed. In one embodiment, the circuitry of the pulse supply 102 limits the plasma discharge current up to a certain level, and if this limit is exceeded, the voltage generated by the power supply 102 drops for a certain period of time. The plasma is maintained by electrons generated by the electric field 149 and also by secondary electron emission from the target 118. In embodiments including the magnet assembly 130, the magnetic field 132 is generated proximate to the target surface 133. The magnetic field 132 confines the primary and secondary electrons in a region 134 thereby concentrating the plasma in the region 134. The magnetic field 132 also induces the electron Hall current 135 proximate to the target surface 133 that further confines the plasma in the region 134. In one embodiment, the magnet assembly 130 includes an electromagnet in addition to a permanent magnet. A magnet power supply (not shown) is electrically connected to the magnetic assembly 130. The magnet power supply can generate a constant current that generates a constant magnetic filed. Alternatively, the magnet power supply can generate a pulse that produces a pulsed magnetic field that creates an increase in electron Hall current 135 proximate to the target surface 133 that further confines the plasma in the region 134. In one embodiment, the pulsing of the magnetic field is synchronized with the pulsing the electric field in the plasma discharge in order to increase the density of the plasma. The sudden increase in the electron Hall current 135 may create a transient non-steady state plasma. Ions in the plasma bombard the target surface 133 because the target 118 is negatively biased. The impact caused by the ions bombarding the target surface 133 dislodges or sputters material from the target 118. The sputtering rate generally increases as the density of the plasma increases. The RF power supply 142 can apply a negative RF bias voltage to the substrate 138 that attracts positively ionized sputtered material to the substrate 138. The sputtered material forms a film of target material on the substrate 138. The magnitude of the RF bias voltage on the substrate 138 can be chosen to optimize parameters, such as sputtering rate and adhesion of the sputtered film to the substrate 138. The magnitude of the RF bias voltage on the substrate 138 can also be chosen to minimize damage to the substrate 138. In embodiments including the temperature controller 148, the temperature of the substrate 138 can be regulated by the temperature controller 148 in order to avoid overheating the substrate 138. Although FIG. 1 illustrates a cross-sectional view of a plasma sputtering apparatus 100, it will be clear to skilled artisans that the principles of the present invention can be used in many other systems, such as plasma etching systems, hollow cathode magnetrons, ion beam generators, plasma-enhanced chemical vapor deposition (CVD) systems, plasma accelerators, plasma rocket thrusters, plasma traps, and any plasma system that uses crossed electric and magnetic fields. FIG. 2 is measured data 150 of discharge voltage as a function of discharge current for a prior art low-current plasma and a high-current plasma according to the present invention. Current-voltage characteristic 152 represents measured data for discharge voltage as a function of discharge current for a plasma generated in a typical commercial magnetron plasma system with a commercially available DC power supply. The actual magnetron plasma system used to obtain the current-voltage characteristics 152 was a standard magnetron with a 10 cm diameter copper sputtering target. Similar results have been observed for a NiV sputtering target. Argon was used as the feed gas and the operating pressure was about 1 mTorr. The current-voltage characteristic 152 illustrates that discharge current increases with voltage. The current-voltage characteristic 152 for the same magnetron plasma system generates a relatively low or moderate plasma density (less than 1012-1013 cm−1, measured close to the cathode/target surface) in a low-current regime. The plasma density in the low-current regime is relatively low because the plasma is mainly generated by direct ionization of ground state atoms in the feed gas. The term “low-current regime” is defined herein to mean the range of plasma discharge current densities that are less than about 0.5 A/cm2 for typical sputtering voltages of between about −300V to −1000V. The power density is less than about 250 W/cm2 for plasmas in the low-current regime. Sputtering with discharge voltages greater than −800V can be undesirable because such high voltages can increase the probability of arcing and can tend to create sputtered films having relatively poor film quality. The current-voltage characteristic 154 represents actual data for a plasma generated by the pulsed power supply 102 in the plasma sputtering system 100 of FIG. 1. The current-voltage characteristic 154 illustrates that the discharge current is about 140 A (˜1.8 A/cm2) at a voltage of about −500V. The discharge current is about 220 A (˜2.7 A/cm2) when the voltage is about −575V. The data depends on various parameters, such as the magnitude and geometry of the magnetic field, chamber pressure, gas flow rate, pumping speed, and the design of the pulsed power supply 102. For certain operating conditions, the discharge current can exceed 375 A with a discharge voltage of only −500V. The voltage-current characteristic 154 is in a high-current regime. The current-voltage characteristic 154 generates a relatively high plasma density (greater than 1012-1013 cm−3) in the high-current regime. The term “high-current regime” is defined herein to mean the range of plasma discharge currents that are greater than about 0.5 A/cm2 for typical sputtering voltages of between about −300V to −1000V. The power density is greater than about 250 W/cm2 for plasmas in the high-current regime. The voltage-current characteristic 154 generates high-density plasmas that can be used for high-deposition rate magnetron sputtering. Some known magnetron systems operate within the high-current regime for very short periods of time. However, these known magnetron systems cannot sustain and control operation in the high-current regime for long enough periods of time to perform any useful plasma processing. The pulsed power supply 102 of the present invention is designed to generate waveforms that create and sustain the high-density plasma with current-voltage characteristics in the high-current regime. FIG. 3 is measured data 200 of a particular voltage pulse 202 generated by the pulsed power supply 102 of FIG. 1 operating in a low-power voltage mode. The pulsed power supply 102 produces a weakly-ionized plasma having a low or moderate plasma density (less than 1012 1013 cm−3) that is typical of known plasma processing systems. The pulsed power supply 102 is operating in a low-power mode throughout the duration of the voltage pulse 202. The pulsed power supply 102 supplies energy to the plasma at a relatively slow rate in the low-power mode. The energy supplied by the pulsed power supply 102 in the low-power mode generates a weakly-ionized plasma by direct ionization of the ground state atoms in the feed gas. The weakly-ionized plasma corresponds to a plasma generated by a conventional DC magnetron. The pulsed power supply 102 can be programmed to generate voltage pulses having various shapes. The desired voltage pulse of FIG. 3 is a square wave voltage pulse as shown by the dotted line 203. However, the actual voltage pulse 202 generated by the pulsed power supply 102 is not perfectly square, but instead includes low frequency oscillations that are inherent to the power supply 102. Some of these low frequency oscillations can be on the order of 50V or more. In addition, the voltage pulse 202 has an initial value 204 of about −115V that is caused by the charge accumulation on the cathode assembly 116 for a particular repetition rate. The voltage pulse 202 includes an ignition stage 205 that is characterized by a voltage 206 having a magnitude and a rise time that is sufficient to ignite a plasma from a feed gas. The magnitude of the voltage pulse 202 rises to about 550V in the ignition stage 205. However, the voltage of the first pulse that initially ignites the plasma can be as high as −1500V. The ignition of the plasma is depicted as a rise in a discharge current 208 through the plasma. The duration of the ignition stage 205 is generally less than about 150 μsec. After the ignition stage 205, the discharge current 208 continues to rise even as the voltage 210 decreases. The rise in the discharge current 208 is caused at least in part by the interaction of the pulsed power supply 102 with the developing plasma. The impedance of the plasma decreases as the current density in the plasma increases. The pulsed power supply 102 attempts to maintain a constant voltage, but the voltage decreases due to the changing plasma resistive load. The peak discharge current 212 is less than about 50 A with a voltage 214 that is about −450V. The power 216 that is present at the peak discharge current 212, which corresponds to a momentary peak density of the plasma, is about 23 kW. As the voltage 218 continues to decrease, the discharge current 220 and the plasma density also decrease. As the density of the plasma decreases, the impedance of the plasma increases. The voltage level 222 corresponds to a quasi-static discharge current 224 that is substantially constant throughout the duration of the voltage pulse 202. This region of quasi-static discharge current 224 is caused by the plasma having a substantially constant resistive load. The term “substantially constant” when applied to discharge current is defined herein to mean a discharge current with less than a 10% variation. After about 200 μsec the oscillations dampen as the voltage 226 fluctuates between about −525V and −575V, the discharge current 228 remains constant with a value of about 25 A and the power 230 is between about 10-15 kW. These conditions correspond to a weakly-ionized or low-density plasma that is typical of most plasma processing systems, such as the conditions represented by the current-voltage characteristic 152 described in connection with FIG. 2. The plasma density is in the range of about 108-1013 cm−3. The total duration of the voltage pulse 202 is about 1.0 msec. The next voltage pulse (not shown) will typically include an ignition stage 205 in order to re-ignite the plasma. However, electrons generated from the first pulse can still be present so the required ignition voltage will typically be much less than the first pulse (on the order of about −600V) and the ignition will typically be much faster (on the order of less than about 200 μsec). FIG. 4 is measured data 250 of a multi-stage voltage pulse 252 that is generated by the pulsed power supply of FIG. 1 that creates a strongly-ionized plasma according to the present invention. The measured data 250 is from a magnetron sputtering system that includes a 10 cm diameter NiV target with an argon feed gas at a pressure of about 10−3 Torr. The multi-stage voltage pulse 252 generates a weakly-ionized plasma in the low-current regime (FIG. 2) initially, and then eventually generates a strongly-ionized or high-density plasma in the high-current regime according to the present invention. Weakly-ionized plasmas are generally plasmas having plasma densities that are less than about 1012-1013 cm−3 and strongly-ionized plasmas are generally plasmas having plasma densities that are greater than about 1012-1013 cm−3. The multi-stage voltage pulse 252 is presented to illustrate the present invention. One skilled in the art will appreciate that there are numerous variations of the exact shape of the multi-stage pulse according to the present invention. The multi-stage voltage pulse 252 is a single voltage pulse having multiple stages as illustrated by the dotted line 253. An ignition stage 254 of the voltage pulse 252 corresponds to a voltage 256 having a magnitude (on the order of about −600V) and a rise time (on the order of about 4V/μsec) that is sufficient to ignite an initial plasma from a feed gas. The initial plasma is typically ignited in less than 200 μsec. A first low-power stage 258 of the voltage pulse 252 has a peak voltage 260 that corresponds to a discharge current 261 in the developing initial plasma. In some embodiments, the ignition stage 254 is integrated into the first low-power stage 258 such that the plasma is ignited during the first low-power stage 258. The peak voltage 260 is about −600V and can range from −300V to −1000V, the corresponding discharge current 261 is about 20 A, and the corresponding power is about 12 kW. In the first low-power stage 258, the pulsed power supply 102 (FIG. 1) is operating in the low-power mode. In the low power mode, the pulsed power supply 102 supplies energy to the initial plasma at a relatively slow rate. The slow rate of energy supplied to the initial plasma in the low-power mode maintains the plasma in a weakly-ionized condition. The weakly-ionized or pre-ionized condition corresponds to an initial plasma having a relatively low (typically less than 1012-1013 cm−3) plasma density. As the density of the initial plasma grows, the voltage 262 decreases by about 50V as the current 261 continues to rise to about 30 A before remaining substantially constant for about 200 μsec. The discharge current 261 rises as the voltage 262 decreases because of the changing impedance of the plasma. As the plasma density changes, the impedance of the plasma and thus the load seen by the pulsed power supply 102 also changes. In addition, the initial plasma can draw energy from the pulsed power supply 102 at a rate that is faster than the response time of the pulsed power supply 102 thereby causing the voltage 262 to decrease. The impedance of the plasma decreases when the number of ions and electrons in the plasma increases as the current density in the initial plasma increases. The increase in the number of ions and electrons decreases the value of the plasma load. The pulsed power supply 102 attempts to maintain a constant voltage. However, the voltage 262 continues to decrease, at least in part, because of the changing plasma load. The substantially constant discharge current corresponds to a conventional DC magnetron discharge current as discussed in connection with current-voltage characteristic 152 of FIG. 2. The initial plasma can correspond to a plasma that is in a steady state or a quasi-steady state condition. The peak plasma density can be controlled by controlling the slope of the rise time of the voltage pulse 252. In a first transient stage 264 of the voltage pulse 252, the voltage increase is characterized by a relatively slow rise time (on the order of about 2.8V/μsec) that is sufficient to only moderately increase the plasma density. The plasma density increases moderately because the magnitude and the rise time of the voltage 266 in the first transient stage 264 is not sufficient to energize the electrons in the plasma to significantly increase an electron energy distribution in the plasma. An increase in the electron energy distribution in the plasma can generate ionizational instabilities that rapidly increase the ionization rate of the plasma. The electron energy distribution and the ionizational instabilities are discussed in more detail with respect to generating a strongly-ionized plasma according to the invention. The moderate increase in the plasma density will result in a current-voltage characteristic that is similar to the current-voltage characteristic 152 of a conventional DC magnetron that was described in connection with FIG. 2. The voltage 266 increases by about 50V to a voltage peak 268 of about −650V. The discharge current 270 increases by about 20 A to about 50 A and the power increases to about 30 kW. The pulsed power supply 102 is still operating in the low-power mode during the first transient stage 264. In a second low-power stage 272 of the voltage pulse 252, the voltage 274 increases slowly by about 40V. The slow voltage increase is characterized by a discharge current 276 that remains substantially constant for about 350 μsec. The plasma can be substantially in a steady state or a quasi-steady state condition corresponding to the current-voltage characteristic 152 of FIG. 2 during the second low-power stage 272. The plasma density in the second low-power stage 272 is greater than the plasma density in the first low-power stage 258, but is still only weakly-ionized. The pulsed power supply 102 is operating in the low-power mode. In a second transient stage 278 of the voltage pulse 252, the pulsed power supply 102 operates in the high-power mode. In this second transient stage 278, the voltage 280 increases sharply compared with the first transient stage 264. The rise time of the voltage 280 is greater than about 0.5V/μsec. The voltage increase is about 60V to the peak voltage. The relatively fast rise time (on the order of about 5V/μsec) of the voltage 280 and the corresponding energy supplied by the pulsed power supply 102 shifts the electron energy distribution in the weakly-ionized plasma to higher energies. The higher energy electrons rapidly ionize the atoms in the plasma and create ionizational instability in the plasma that drives the weakly-ionized plasma to a non-steady state condition or a transient state. In a non-steady state, the Boltzman, Maxwell, and Saha distributions can be modified. The rapid increase in ionization of the atoms in the plasma results in a rapid increase in electron density and a formation of the strongly-ionized plasma that is characterized by a significant rise in the discharge current 282. The discharge current 282 rises to about 250 A at a non-linear rate for about 250 μsec. One mechanism that contributes to a sharp increase in the electron energy distribution is known as diocotron instability. Diocotron instability is a wave phenomena that relates to the behavior of electron density gradients in the presence of electric and magnetic fields. Electron electrostatic waves can propagate along and across (parallel to and perpendicular to) field lines with different frequencies. These electron electrostatic waves can create electron drifts in the presence of a perpendicular electric field that are perpendicular to magnetic field lines. Such electron drifts are inherently unstable, since any departure from charge neutrality in the form of charge bunching and separation (over distances on the order of the characteristic length scale in a plasma, the Debye length) create electric fields which cause second order ExB drifts that can exacerbate the perturbation. These instabilities are referred to as gradient-drift and neutral-drag instabilities. A charge perturbation associated with an electron Hall current developed by crossed magnetic and electric fields can produce radial electron drift waves. Drifts driven by the two density gradients (perpendicular and parallel) associated with a maximum in the radial electron density distribution can interact to cause the diocotron instability. Diocotron instability is described in “Magnetron Sputtering: Basic Physics and Application to Cylindrical Magnetrons” by John A. Thorton., J. Voc. Sci. Technol. 15(2), March/April p. 171-177, 1978. A high-power stage 283 includes voltage oscillations 284 that have peak-to-peak amplitudes that are on the order of about 50V. These “saw tooth” voltage oscillations 284 may be caused by the electron density forming a soliton waveform or having another non-linear mechanism, such as diocotron instability discussed above, that increases the electron density as indicated by the increasing discharge current 286. The soliton waveform or other non-linear mechanism may also help to sustain the high-density plasma throughout the duration of the voltage pulse 252. Soliton waveforms, in particular, have relatively long lifetimes. The discharge current 286 increases non-linearly through the high-power stage 283 until a condition corresponding to the voltage-current characteristic 154 of FIG. 2 is reached. This condition corresponds to the point in which the pulsed power supply 102 is supplying an adequate amount of continuous power to sustain the strongly-ionized plasma at a constant rate as illustrated by a substantially constant discharge current 287. The peak discharge current 288 in the high-power stage 283 is about 250 A at a voltage 290 of about −750V. The corresponding peak power 292 is about 190 kW. The voltage pulse 252 is terminated at about 1.24 msec. The cathode assembly 116 remains negatively biased at about −300V after the termination of the voltage pulse 252. The plasma then rapidly decays as indicated by the rapidly decreasing discharge current 294. The high-power stage 283 of the voltage pulse is sufficient to drive the plasma from a non-steady state in the second transient stage 278 to a strongly-ionized state corresponding to the voltage-current characteristic 154 of FIG. 2. The pulsed power supply 102 must supply a sufficient amount of uninterrupted power to continuously drive the initial plasma in the weakly-ionized state (in the second low-power stage 272) through the transient non-steady state (in the second transient stage 278) to the strongly-ionized state (in the high-power stage 283). The rise time of the voltage 280 in the second transient stage 278 is chosen to be sharp enough to shift the electron energy distribution of the initial plasma to higher energy levels to generate ionizational instabilities that creates many excited and ionized atoms. The rise time of the voltage 280 is greater than about 0.5V/μsec. The magnitude of the voltage 280 in the second transient stage 278 is chosen to generate a strong enough electric field between the target 118 and the anode 124 (FIG. 1) to shift the electron energy distribution to high energies. The higher electron energies create excitation, ionization, and recombination processes that transition the state of the weakly-ionized plasma to the strongly-ionized state. The transient non-steady state plasma state exists for a time period during the second transient stage 278. The transient state results from plasma instabilities that occur because of mechanisms, such as increasing electron temperature caused by ExB Hall currents. Some of these plasma instabilities are discussed herein. The strong electric field generated by the voltage 280 between the target 118 and the anode 124 (FIG. 1) causes several ionization processes. The strong electric field causes some direct ionization of ground state atoms in the weakly-ionized plasma. There are many ground state atoms in the weakly-ionized plasma because of its relatively low level of ionization. In addition, the strong electric field heats electrons initiating several other different type of ionization process, such as electron impact, Penning ionization, and associative ionization. Plasma radiation can also assist in the formation and maintenance of the high current discharge. The direct and other ionization processes of the ground state atoms in the weakly-ionized plasma significantly increase the rate at which a strongly-ionized plasma is formed. In one embodiment, the ionization process is a multi-stage ionization process. The multi-stage voltage pulse 252 initially raises the energy of the ground state atoms in the weakly-ionized plasma to a level where the atoms are excited. For example, argon atoms require an energy of about 11.55 eV to become excited. The magnitude and rise time of the voltage 280 is then chosen to create a strong electric field that ionizes the exited atoms. Excited atoms ionize at a much higher rate than neutral atoms. For example, Argon excited atoms only require about 4 eV of energy to ionize while neutral atoms require about 15.76 eV of energy to ionize. The multi-step ionization process is described in co-pending U.S. patent application Ser. No. 10/249,844, entitled High-Density Plasma Source using Excited Atoms which is assigned to the present assignee. The entire disclosure of U.S. patent application Ser. No. 10/249,844 is incorporated herein by reference. The multi-step ionization process can be described as follows: Ar+e−→Ar*+e− Ar*+e−→Ar++2e− where Ar represents a neutral argon atom in the initial plasma, e− represents an ionizing electron generated in response to an electric field, and Ar* represents an excited argon atom in the initial plasma. The collision between the excited argon atom and the ionizing electron results in the formation of an argon ion (Ar+) and two electrons. In one embodiment, ions in the developing plasma strike the target 118 causing secondary electron emission. These secondary electrons interact with neutral or excited atoms in the developing plasma. The interaction of the secondary electrons with the neutral or excited atoms further increases the density of ions in the developing plasma as the feed gas 108 is replenished. Thus, the excited atoms tend to more rapidly ionize near the target surface 133 (FIG. 1) than the neutral argon atoms. As the density of the excited atoms in the plasma increases, the efficiency of the ionization process rapidly increases. The increased efficiency can result in an avalanche-like increase in the density of the plasma thereby creating a strongly-ionized plasma. In one embodiment, the magnet assembly 130 generates a magnetic field 132 proximate to the target 118 that is sufficient to generate an electron ExB Hall current 135 (FIG. 1) which causes the electron density in the plasma to form a soliton or other non-linear waveform that increases at least one of the density and lifetime of the plasma as previously discussed. In some embodiments, the strength of the magnetic field 132 required to cause the electron density in the plasma to form such a soliton or non-linear waveform is in the range of fifty to ten thousand gauss. An electron ExB Hall current 135 is generated when the voltage pulse 252 applied between the target 118 and the anode 124 generates primary electrons and secondary electrons that move in a substantially circular motion proximate to the target 118 according to crossed electric and magnetic fields. The magnitude of the electron ExB Hall current 135 is proportional to the magnitude of the discharge current in the plasma. In some embodiments, the electron ExB Hall current 135 is approximately in the range of three to ten times the magnitude of the discharge current. The electron ExB Hall current 135 defines a substantially circular shape when the plasma density is relatively low. The substantially circular electron ExB Hall current 135 tends to form a more complex shape as the current density of the plasma increases. The shape is more complex because of the electron ExB Hall current 135 generates its own magnetic field that interacts with the magnetic field generated by the magnet assembly 130 and the electric field generated by the voltage pulse 252. In some embodiments, the electron ExB Hall current 135 becomes cycloidal shape as the current density of the plasma increases. The electron density in the plasma can form a soliton or other non-linear waveforms when the small voltage oscillations 284 create a pulsing electric field that interacts with the electron ExB Hall current 135. The small voltage oscillations 284 tend to create oscillations in the plasma density that increase the density and lifetime of the plasma. The increase in plasma density shown in FIG. 4 in the time period between about 900 μsec and 1.2 msec can be the result of the electron density forming a soliton or other non-linear waveform. In this time period, the voltage is only slightly increasing with time, but the discharge current 286 increases at a much more rapid rate. In one embodiment, the electron density increases in an avalanche-like manner because of electron overheating instability. Electron overheating instabilities can occur when heat is exchanged between the electrons in the plasma, the feed gas, and the walls of the chamber. For example, electron overheating instabilities can be caused when electrons in a weakly-ionized plasma are heated by an external field and then lose energy in elastic collisions with atoms in the feed gas. The elastic collisions with the atoms in the feed gas raise the temperature and lower the density of the feed gas. The decrease in the density of the gas results in an increase in the electron temperature because the frequency of elastic collisions in the feed gas decreases. The increase in the electron temperature again enhances the heating of the gas. The electron heating effect develops in an avalanche-like manner and can drive the weakly-ionized plasma into the transient non-steady state. FIG. 5A-FIG. 5C are measured data 300, 300″, and 300′″ of other illustrative multi-stage voltage pulses 302, 302′, and 302″ generated by the pulsed power supply 102 of FIG. 1. The desired pulse shapes requested from the pulsed power supply 102 are superimposed in dotted lines 304, 304′, and 304″ onto each of the respective multi-stage voltage pulses 302, 302′, and 302″. The voltage pulses 302, 302′, and 302″ are generated for a magnetron sputtering source having a 10 cm diameter copper target and operating with argon feed gas at a chamber pressure of approximately 10−1 Torr. The repetition rate of the voltage pulses is 40 Hz. The voltage pulse 302 illustrated in FIG. 5A is a two-stage voltage pulse 302 having a transient region included in both the low-power stage and the high-power stage of the pulse. A low-power stage 306 of the voltage pulse 302 including the first transient region is sufficient to ignite an initial plasma and eventually sustain a weakly-ionized plasma. The duration of the low-power stage 306 of the voltage pulse 302 is about 1.0 msec. The relatively fast rise time (on the order of about 6.25V/μsec) of the voltage during the first transient region in the low-power stage 306 is sufficient to shift the electron energy distribution of the initial plasma to higher energies to generate ionizational instability that drives the initial plasma into a transient non-steady state condition. The rise time of the voltage should be greater than about 0.5V/μsec as previously discussed. However, since the pulsed power supply 102 is operating in a low-power mode during the low-power stage 306 of the voltage pulse 302, it does not supply a sufficient amount of uninterrupted power to continuously drive the initial plasma from the transient non-steady state to a strongly-ionized state corresponding to the current-voltage characteristic 154 of FIG. 2. Since there is insufficient energy stored in the pulsed power supply 102 in the low-power mode to create conditions that can sustain a strongly-ionized plasma, the plasma density oscillates and eventually the transient non-steady state of the plasma becomes weakly-ionized corresponding to the current-voltage characteristic 152 of FIG. 2. The low-power stage 306 of the voltage pulse 302 includes relatively large voltage oscillations 308. The voltage oscillations 308 dampen when the initial plasma reaches the weakly-ionized condition corresponding to the current-voltage characteristic 152 of FIG. 2. The weakly-ionized plasma is characterized by the substantially constant discharge current 312. The voltage oscillations 308 occur because the pulsed power supply 102 does not supply enough energy in the low-power mode to drive the transient plasma into the strongly-ionized state that corresponds to the high-current regime illustrated by the current-voltage characteristic 154 of FIG. 2. Consequently, the discharge current 310 oscillates as the plasma rapidly expands and contracts. The rapidly expanding and contracting plasma causes the output voltage 308 to oscillate in response to the changing plasma load. The rapidly expanding and contracting plasma also prevents the electron density in the plasma from forming a soliton or other non-linear waveform that can increase the plasma density. The average power 314 during the generation of the initial plasma is less than about 50 kW. The voltage 316 and the discharge current 318 are substantially constant after about 500 μsec, which corresponds to a plasma in a weakly-ionized condition. A high-power stage 320 of the voltage pulse 302 includes a second transient region 321. The voltage increases by about 30V in the second transient region 321. The pulsed power supply 102 generates the high-power stage 320 of the voltage pulse 304 at about 1.1 msec. The voltage in the second transient region 321 has a magnitude and a rise time (on the order of about 5V/μsec) that is sufficient to drive the weakly-ionized plasma into a transient non-steady state. The rise time of the voltage is greater than about 0.5V/μsec. In the high-power stage 320, the pulsed power supply 102 is operating in the high-power mode and supplies a sufficient amount of uninterrupted power to drive the weakly-ionized plasma from the transient non-steady state to a strongly-ionized state corresponding to the current-voltage characteristic 154 of FIG. 2. Voltage oscillations 322 occur for about 300 μsec. The voltage oscillations 322 create current oscillations 324 in the transient plasma. The voltage oscillations 322 are caused, at least in part, by the changing resistive load in the plasma. The pulsed power supply 102 attempts to maintain a constant voltage and a constant discharge current, but the transient plasma exhibits a rapidly changing resistive load. The voltage oscillations 322 can also be caused by ionizational instabilities in the plasma as previously discussed. Ionizational instabilities can occur when the degree of ionization in the plasma changes because of varying magnitudes of the crossed electric and magnetic fields. The degree of ionization can grow exponentially as the ionizational instability develops. The exponential growth in ionization may be a consequence of electron gas overheating as a result of developing electron Hall currents. The exponential growth in ionization dramatically increases the discharge current. The voltage oscillations 322 are minimized after about 1.5 msec. The minimum voltage oscillations 323 can create a pulsing electric field that interacts with the electron ExB Hall current 135 (FIG. 1) to generate oscillations in the plasma density that increase the density and lifetime of the plasma. The plasma is in the high-current regime corresponding to the current-voltage characteristic 154 of FIG. 2 in which the pulsed power supply 102 supplies an adequate amount of energy to increase the density of the plasma non-linearly to the strongly-ionized state. The average voltage 326 is substantially constant while the current 328 increases nonlinearly with insignificant oscillations. After the voltage oscillations 322, the average voltage 326 remains lower than the voltage 316 present during the low-power stage 306 of the voltage pulse 304. The discharge current 324 rises to a peak current 330. After about 2.0 msec the average voltage 326 is about −500V, the discharge current 330 is almost 300 A and the power 332 is about 150 kW. These conditions correspond to a strongly-ionized plasma in the high-current regime. The pulsed power supply 102 supplies power to the transient plasma during the high-power stage 320 at a relatively slow rate. This relatively slow rate corresponds to a relatively slow rate of increase in the discharge current 328 over a time period of about 1.0 msec. In one embodiment of the invention, the pulsed power supply 102 supplies high-power to the plasma relatively quickly thereby increasing the density of the plasma more rapidly. The density of the plasma can also be increased by increasing the pressure inside the plasma chamber. FIG. 5A illustrates that in order to sustain a strongly-ionized plasma in the high-current regime corresponding to the current-voltage characteristic 154 of FIG. 2 at least two conditions must be satisfied. The first condition is that the rise time of a voltage in a transient region must be sufficient to shift the electron energy distribution of the initial plasma to higher energies to generate ionizational instability that drives the plasma into a transient non-steady state condition. The second condition is that the pulsed power supply must supply a sufficient amount of uninterrupted power to drive the plasma from the transient non-steady state to a strongly-ionized state corresponding to the current-voltage characteristic 154 of FIG. 2. In the low-power stage 306, the voltage in the first transient region has a sufficient rise time to shift the electron energy distribution of the initial plasma to higher energies as shown by current oscillations 310. However, the pulsed power supply 102 is in the low-power mode and does not supply a sufficient amount of uninterrupted power to drive the initial plasma from the transient non-steady state to a strongly-ionized state. In the high-power stage 320, the voltage in the second transient region 321 has a sufficient rise time to shift the electron energy distribution of the initial plasma to higher energies as shown by current oscillations 324. Also, the pulsed power supply 102 (in the high-power mode) supplies a sufficient amount of uninterrupted power to drive the weakly-ionized plasma from the transient non-steady state to a strongly-ionized state. FIG. 5B is measured data 300′ of another illustrative multi-stage voltage pulse 302′ generated by the pulsed power supply 102 of FIG. 1. The voltage pulse 302′ is a three-stage voltage pulse 302′. The low-power stage 306′ of the voltage pulse 302′ including a first transient region has a rise time and magnitude that ignites an initial plasma. The low-power stage 306′ corresponds to a low-power mode of the pulsed power supply 102 and is similar to the low-power stage 306 of the voltage pulse 302 that was described in connection with FIG. 5A. A transient stage 340 of the three-stage voltage pulse 302′ is a transition stage where the pulsed power supply 102 transitions from the low-power mode to the high-power mode. The duration of the transient stage 340 is about 40 μsec, but can have a duration that is in the range of about 10 μsec to 5,000 μsec. The discharge voltage 342 and discharge current 344 both increase sharply in the transient stage 340 as previously discussed. The transient stage 340 of the voltage pulse 302′ has a rise time that shifts the electron energy distribution in the weakly-ionized plasma to higher energies thereby causing a rapid increase in the ionization rate by driving the weakly-ionized plasma into a transient non-steady state. Plasmas can be driven into transient non-steady states by creating plasma instabilities from the application of a strong electric field. A high-power stage 350 of the three-stage voltage pulse 302′ is similar to the high-power stage 320 of the two-stage voltage pulse 302 that was described in connection with FIG. 5A. However, the discharge current 352 increases at a much faster rate than the discharge current 328 that was described in connection with FIG. 5A. The discharge current 328 increases more rapidly because the transient stage 340 of the voltage pulse 302′ supplies high power to the weakly-ionized initial plasma at a rate and duration that is sufficient to more rapidly create a strongly-ionized plasma having a discharge current 352 that increases non-linearly. Voltage oscillations 354 in the high-power stage 350 are sustained for about 100 μsec. The voltage oscillations can are caused by the ionizational instabilities in the plasma as described herein, such as diocotron oscillations. The voltage oscillations 354 cause current oscillations 356. The maximum power 358 in the third stage 350 is approaching 200 kW, which corresponds to a maximum discharge current 360 that is almost 350 A. The third stage 350 of the voltage pulse 302′ is terminated after about 1.0 msec. FIG. 5C is measured data 300″ of another illustrative multi-stage voltage pulse 302″ generated by the pulsed power supply 102 of FIG. 1. The voltage pulse 302″ is a three-stage voltage pulse 302″. The low-power stage 306″ of the voltage pulse 302″ including a first transient region has a rise time and magnitude that ignites an initial plasma. The low-power stage 306″ corresponds to a low-power mode of the pulsed power supply 102 and is similar to the low-power stage 306 of the voltage pulse 302 that was described in connection with FIG. 5A and the low-power stage 306′ of the voltage pulse 302′ that was described in connection with FIG. 5B. A transient stage 370 of the three-stage voltage pulse 302″ is a transition stage where the pulsed power supply 102 transitions from the low-power mode to the high-power mode. The duration of the transient stage 370 is about 60 μsec, which is about 1.5 times longer than the duration of the transient stage 340 of the voltage pulse 302′ that was described in connection with FIG. 5B. The peak-to-peak magnitude of the voltage 376 (˜100V) is greater than the peak-to-peak magnitude of the voltage 346 (˜70V) of FIG. 5B. The discharge voltage 372 and discharge current 374 both increase sharply in the transient stage 370 because of the high value of the peak-to-peak magnitude of the voltage 376. The magnitude and rise time of the transient stage 370 is sufficient to drive the initial plasma into a non-steady state condition. The discharge voltage 372 and the discharge current 374 increase sharply. The peak discharge voltage 376 is about −650V, which corresponds to a discharge current 377 that is greater than about 200 A. The discharge voltage 378 then decreases as the discharge current 374 continues to increase. The discharge current 374 in the transient stage 370 increases at a much faster rate than the discharge current 352 that was described in connection with FIG. 5B because the peak-to-peak magnitude of the voltage 376 is higher and the duration of the transient stage 370 is longer than in the transient stage 340 of FIG. 5B. The duration of the transient stage 370 is long enough to supply enough uninterrupted energy to the weakly-ionized plasma to rapidly increase the rate of ionization of the transient plasma. A high-power stage 380 of the three-stage voltage pulse 302″ is similar to the high-power stage 350 of the three-stage voltage pulse 302′ that was described in connection with FIG. 5B. However, the voltage pulse 302″ does not include the large voltage oscillations that were described in connection with FIGS. 5A and 5B. The large voltage oscillations are not present in the voltage pulse 302″ because the transient plasma is already substantially strongly-ionized as a result of the energy supplied in the transient stage 370. Consequently, the initial plasma transitions in a relatively short period of time from a weakly-ionized condition to a strongly-ionized condition. Small voltage oscillations 384 in the voltage pulse 302″ may be caused by the electron density forming a soliton waveform or having another non-linear mechanism that increases the electron density as indicated by the increasing discharge current 286. The soliton waveform or other non-linear mechanism may also help to sustain the high-density plasma throughout the duration of the voltage pulse 302′. The discharge current 382 in the third stage 380 is greater than about 300 A. The maximum power 386 in the third stage 380 approaches 200 kW. The third stage 380 of the voltage pulse 304″ is terminated after about 1.0 msec. FIG. 6A and FIG. 6B are measured data of multi-stage voltage pulses 400, 400′ generated by the pulsed power supply 102 of FIG. 1 that illustrate the effect of pulse duration in the transient stage of the pulse on the plasma discharge current. The multi-stage voltage pulses 400, 400′ were applied to a standard magnetron with a 15 cm diameter copper target. The feed gas was argon and the chamber pressure was about 3 mTorr. The multi-stage voltage pulse 400 shown in FIG. 6A is a three-stage voltage pulse 402 as indicated by the dotted line 404. A low-power stage 406 of the voltage pulse 402 has a magnitude and a rise time that is sufficient to ignite a feed gas and generate an initial plasma. The pulsed power supply 102 is operating in the low-power mode during the low-power stage 406. The maximum voltage in the low-power stage 406 is about −550V. The initial plasma develops into a weakly-ionized plasma having a relatively low-level of ionization corresponding to the current-voltage characteristic 152 of FIG. 2. The weakly-ionized plasma can be in a steady state corresponding to a substantially constant discharge current 408 that is less than about 50 A. The pulsed power supply 102 is in the high-power mode during a transient stage 410. In the transient stage 410, the voltage increases by about 100V. The rise time of the voltage increase is sufficient to create a strong electric field through the weakly-ionized plasma that promotes excitation, ionization, and recombination processes. The excitation, ionization, and recombination processes create plasma instabilities, such as ionizational instabilities, that result in voltage oscillations 412. The duration of the transient stage 410 of the voltage pulse 402 is, however, insufficient to shift the electron energy distribution in the plasma to higher energies because the energy supplied by the pulsed power supply 102 in the transient stage 410 is terminated abruptly as illustrated by the dampening discharge current 414. Consequently, the transient plasma exhibits ionizational relaxation and eventually decays to a weakly-ionized plasma state corresponding to a substantially constant discharge current 416. A high-power stage 418 of the voltage pulse 402 has a lower magnitude than the transient stage 410 of the voltage pulse, but a higher magnitude than the low-power stage 406. The high-power stage 418 is sufficient to maintain the weakly-ionized plasma, but cannot drive the plasma from the weakly-ionized condition to the strongly-ionized condition corresponding to the current-voltage characteristic 154 of FIG. 2. This is because the transient stage 410 did not provide the conditions necessary to sufficiently shift the electron energy distribution in the weakly-ionized plasma to high enough energies to create ionizational instabilities in the plasma. The voltage pulse 402 is terminated after about 2.25 msec. The multi-stage voltage pulse 400′ illustrated in FIG. 6B is a three-stage voltage pulse 402′ as indicated by the dotted line 404′. A low-power stage 406′ of the voltage pulse 402′ is similar to the low-power stage 406 of the voltage pulse 402 that was described in connection with FIG. 6A. The low-power stage 406′ has a magnitude and a rise time that is sufficient to ignite a feed gas and generate an initial plasma. The pulsed power supply 102 is operating in the low-power mode during the low-power stage 406′. The maximum voltage in the low-power stage is also about −550V. The initial plasma develops into a weakly-ionized plasma having a relatively low-level of ionization corresponding to the current-voltage characteristic 152 of FIG. 2. The weakly-ionized plasma can be in a steady state corresponding to a substantially constant discharge current 408′ that is less than about 50 A. The transient stage 410′ of the voltage pulse 402′ creates a strong electric field through the weakly-ionized plasma that promotes excitation, ionization, and recombination processes. The excitation, ionization, and recombination processes create plasma instabilities, such as ionizational instabilities, that result in voltage oscillations 412′. The rise time of the peaks in the oscillating voltage 412′ create instabilities in the weakly-ionized plasma that rapidly increase the ionization rate of the weakly-ionized plasma as illustrated by the rapidly increasing discharge current 414′. The duration of the transient stage 410′ of the voltage pulse 402′ is sufficient to shift the electron energy distribution in the plasma to higher energies that rapidly increase the ionization rate. The duration of the transient stage 410′ of FIG. 6B is five times more than the duration of the transient stage 410 of FIG. 6A. The discharge current 420 increases nonlinearly as the average discharge voltage 422 decreases. The magnitude of the discharge current can be controlled by varying the magnitude and the duration of the transient stage 410′ of the voltage pulse 402′. The high-power stage 418′ of the voltage pulse 402′ has a lower magnitude than the transient stage 410′. The pulsed power supply 102 provides a sufficient amount of energy during the high-power stage 418′ to maintain the plasma in a strongly-ionized condition corresponding to the current-voltage characteristic 154 of FIG. 2. The maximum discharge current 416′ for the plasma in the strongly-ionized state is about 350 A. The voltage pulse 402′ is terminated after about 2.25 msec. FIG. 7A and FIG. 7B are measured data of multi-stage voltage pulses 430, 430′ generated by the pulsed power supply 102 of FIG. 1 that show the effect of the pulsed power supply operating mode on the plasma discharge current. The multi-stage voltage pulses 430, 430′ were applied to a standard magnetron with a 15 cm diameter copper target. The feed gas was argon and the chamber pressure was about 3 mTorr. The multi-stage voltage pulse 430 shown in FIG. 7A is a three-stage voltage pulse 432 as indicated by the dotted line 434. The pulsed power supply 102 generates a low-power stage 436 of the voltage pulse 432 that has a magnitude and a rise time that is sufficient to ignite a feed gas to generate an initial plasma. The maximum voltage in the ignition stage is about −550V. The pulsed power supply 102 is operating in the low-power mode. The initial plasma develops into a weakly-ionized plasma having a relatively low-level of ionization corresponding to the current-voltage characteristic 152 of FIG. 2. The weakly-ionized plasma can be in a steady state corresponding to a substantially constant discharge current 408′ that is less than about 50 A. The pulsed power supply 102 generates a transient stage 440 of the voltage pulse 432 that increases the voltage by about 150V. The rise time, amplitude and duration of the voltage in the transient stage 440 of the voltage pulse 432 is sufficient to promote enough excitation, ionization, and recombination processes for the weakly-ionized plasma to experience a high rate of ionization as illustrated by the rapidly increasing discharge current 442. The pulsed power supply 102 is operating in a high-power mode during the transient stage 440. The high-power stage 444 of the voltage pulse 432 has a lower magnitude than the transient stage 440 but has a sufficient magnitude to maintain the strongly-ionized plasma in the high-current regime corresponding to the current-voltage characteristic 154 of FIG. 2. The discharge current 446 for the strongly-ionized plasma is about 350 A. The pulsed power supply 102 operates in the high-power mode during the high-power stage 444 and generates enough uninterrupted energy to sustain the strongly-ionized plasma. The voltage pulse 432 is terminated after about 2.25 msec. The multi-stage voltage pulse 430′ of FIG. 7B is a three-stage voltage pulse 432′ as indicated by the dotted line 434′. The pulsed power supply generates a low-power stage 436′ of the voltage pulse 432′ that is similar to the low-power stage 436 of the voltage pulse 432 of FIG. 7A. The low-power stage 436′ of the voltage pulse 432′ has a magnitude and a rise time that is sufficient to ignite a feed gas to generate an initial plasma. The pulsed power supply 102 is operating in the low-power mode. The maximum voltage in the ignition stage is about −550V. The initial plasma develops into a weakly-ionized plasma having a relatively low-level of ionization. The weakly-ionized plasma can be in a steady state that corresponds to a substantially constant discharge current 438′ that is less than about 50 A. The pulsed power supply 102 generates a transient stage 440′ of the voltage pulse 432′ that increases the voltage by about 150V. The transient stage 440′ is similar to the transient stage 440 of FIG. 7A. The amplitude and duration of the transient stage 440′ of the voltage pulse 432′ is sufficient to promote enough excitation, ionization, and recombination processes to rapidly increase the ionization rate of the weakly-ionized plasma as illustrated by the rapidly increasing discharge current 442′. The pulsed power supply 102 is operating in a high-power mode during the transient stage 440′. The pulsed power supply 102 generates a high-power stage 444′ that includes a voltage having a lower magnitude than the voltage in the second stage 440′. The voltage in the high-power stage 444′ decreases to below 500V which is insufficient to sustain a strongly-ionized plasma. Thus, the strongly-ionized plasma exhibits ionizational relaxation and eventually decays to a weakly-ionized plasma state corresponding to a quasi-stationary discharge current 449. The voltage pulse 432′ is terminated after about 2.25 msec. FIG. 8 is measured data 450 for an exemplary single-stage voltage pulse 452 generated by the pulsed power supply 102 of FIG. 1 that produces a high-density plasma according to the invention that is useful for high-deposition rate sputtering. The voltage pulse 452 is a single-stage voltage pulse as indicated by the dotted line 453. The pulsed power supply 102 operates in a high-power mode throughout the duration of the voltage pulse 452. The voltage pulse 452 includes an ignition region 454 that has a magnitude and a rise time that is sufficient to ignite a feed gas to generate an initial plasma. The discharge current 458 increases after the initial plasma is ignited. The initial plasma is ignited in about 100 μsec. After ignition, the discharge current 460 and the voltage 456 both increase. The initial peak voltage 462 is about 900V. The voltage then begins to decrease. The discharge current 460 reaches an initial peak current 464 corresponding to a voltage 466. The initial peak discharge current 464 is about 150 A at a discharge voltage 466 of about The peak discharge current 464 and corresponding discharge voltage 466 corresponds to a power 468 that is about 120 kW. The time period from the ignition of the plasma to the initial peak discharge current 464 is about 50 μsec. The initial plasma does not reach a steady state condition but instead remains in a transient state. The voltage pulse 452 also includes a transient region 454′ having voltage oscillations 467 that include rise times which are sufficient to shift the electron energy distribution in the initial plasma to higher energies that create ionizational instabilities that cause a rapid increase in the ionization rate as described herein. The initial plasma remains in a transient state. The voltage pulse 452 also includes a high-power region 454″. The voltage in the high-power region 454″ has a magnitude that is sufficient to sustain a strongly-ionized plasma. Small voltage oscillations 469 in the voltage pulse 452 may be caused by the electron density forming a soliton waveform or having another non-linear mechanism that increases the electron density as indicated by the increasing discharge current 470. The soliton waveform or other non-linear mechanism may also help to sustain the strongly-ionized plasma throughout the duration of the voltage pulse 452. The single-stage voltage pulse 452 includes a voltage 456 that is sufficient to ignite an initial plasma, voltage oscillations 467 that are sufficient to create ionizational instabilities in the initial plasma, and a voltage 472 that is sufficient to sustain the strongly-ionized plasma. The pulsed power supply 102 operates in the high-power mode throughout the duration of the single-stage voltage pulse 452. The peak discharge current 470 in the high-density plasma is greater than about 250 A for a discharge voltage 472 of about −500V. The power 474 is about 125 kW. The pulse width of the voltage pulse 452 is about 1.0 msec. FIG. 9 illustrates a cross-sectional view of a plasma sputtering apparatus 500 having a pulsed direct current (DC) power supply 501 according to another embodiment of the invention. The plasma sputtering apparatus 500 includes a vacuum chamber 104 for containing a plasma. The vacuum chamber 104 can be coupled to ground 105. The vacuum chamber 104 is positioned in fluid communication with a vacuum pump 106 that is used to evacuate the vacuum chamber 104 to high vacuum. The pressure inside the vacuum chamber 104 is generally less than 10−1 Torr for most plasma operating conditions. The plasma sputtering apparatus 500 also includes a cathode assembly 502. The cathode assembly 502 is generally in the shape of a circular ring. The cathode assembly 502 includes a target 504. The target 504 is generally in the shape of a disk and is secured to the cathode assembly 502 through a locking mechanism, such as a clamp 506. The cathode assembly 502 is electrically connected to a first terminal 508 of the pulsed power supply 501 with an electrical transmission line 510. In some embodiments, the plasma sputtering apparatus 500 includes an energy storage device 503 that provides a source of energy that can be controllably released into the plasma. The energy storage device 503 is electrically coupled to the cathode assembly 502. In one embodiment, the energy storage device 503 includes a capacitor bank. A ring-shaped anode 512 is positioned in the vacuum chamber 104 proximate to the cathode assembly 502 so as to form a gap 514 between the anode 512 and the cathode assembly 502. The gap 514 can be between about 1.0 cm and 12.0 cm wide. The gap 514 can reduce the probability that an electrical breakdown condition (i.e., arcing) will develop in the chamber 104. The gap 514 can also promote increased homogeneity of the plasma by controlling a gas flow through the gap. The anode 512 can include a plurality of feed gas injectors 516 that inject feed gas into the gap 514. In the embodiment shown, the feed gas injectors 516 are positioned within the anode 512. The feed gas injectors 516 are coupled to one or more feed gas sources 518. The feed gas sources can include atomic feed gases, reactive gases, or a mixture of atomic and reactive gases. Additionally, excited atom sources (not shown) or metastable atom sources (not shown) can be coupled to the feed gas injectors 516 to supply excited atoms or metastable atoms to the chamber 104. The anode 512 is electrically connected to ground 105. A second terminal 520 of the pulsed power supply 501 is also electrically connected to ground 105. In other embodiments, the anode 512 is electrically connected to the second terminal 520 of the pulsed power supply 501. The anode 512 can be integrated with or connected to a housing 521 that surrounds the cathode assembly 502. An outer edge 522 of the cathode 502 is isolated from the housing 521 with insulators 523. The space 524 between the outer edge 522 of the cathode assembly 502 and the housing 521 can be filled with a dielectric. The plasma sputtering apparatus 500 can include a magnet assembly 525 that generates a magnetic field 526 proximate to the target 504. The magnetic field 526 is less parallel to the surface of the cathode assembly 502 at the poles of the magnets in the magnet assembly 525 and more parallel to the surface of the cathode assembly 502 in the region 527 between the poles of the magnets in the magnetic assembly 525. The magnetic field 526 is shaped to trap and concentrate secondary electrons emitted from the target 504 that are proximate to the target surface 528. The magnetic field 526 increases the density of electrons and therefore, increases the plasma density in the region 527. The magnetic field 526 can also induce an electron Hall current that is generated by the crossed electric and magnetic fields. The strength of the electron Hall current depends, at least in part, on the density of the plasma and the strength of the crossed electric and magnetic fields. Crossed electric and magnetic fields generated in the gap 514 can enhance the ionizational instability effect on the plasma as discussed herein. The plasma sputtering apparatus 500 also includes a substrate support 530 that holds a substrate 532 or other work piece. The substrate support 530 can be electrically connected to a first terminal 534 of a RF power supply 536 with an electrical transmission line 538. A second terminal 540 of the RF power supply 536 is coupled to ground 105. The RF power supply 536 can be connected to the substrate support 530 through a matching unit (not shown). In one embodiment a temperature controller 542 is thermally coupled to the substrate support 530. The temperature controller 542 regulates the temperature of the substrate 532. The plasma sputtering apparatus 500 can also include a cooling system 544 to cool the target 504 and the cathode assembly 502. The cooling system 544 can be any one of numerous types of liquid or gas cooling system that are known in the art. In operation, the vacuum pump 106 evacuates the chamber 104 to the desired operating pressure. The feed gas is injected into the chamber 104 from the feed gas source 518 through the gas inlet 516. The pulsed power supply 501 applies negative voltage pulses to the cathode 502 (or positive voltage pulses to the anode 512) that generate an electric field 546 in the gap 514 between the cathode assembly 502 and the anode 512. The magnitude and rise time of the voltage pulse are chosen such that the resulting electric field 546 ionizes the feed gas in the gap 514, thereby igniting an initial plasma in the gap 514. The geometry of the gap 514 can be chosen to minimize the probability of arcing and to facilitate the generation of a very strong electric field 546 with electric field lines that are perpendicular to the surface 528 of the target 504 and the cathode 502. This strong electric field 546 can enhance the ionizational instability in the plasma by increasing the volume of excited atoms including metastable atoms that are generated from ground state atoms in the initial plasma. The increased volume of exited atoms can increase the density of the plasma in a non-linear manner as previously discussed. The plasma is maintained, in part, by secondary electron emission from the target 504. In embodiments including the magnet assembly 525, the magnetic field 526 confines the secondary electrons proximate to the region 527 and, therefore, concentrates the plasma proximate to the target surface 528. The magnetic field 526 also induces an electron Hall current proximate to the target surface 528, which further confines the plasma and can cause the electron density to form a soliton waveform or other non-linear waveform. Ions in the plasma bombard the target surface 528 since the target 504 is negatively biased. The impact caused by the ions bombarding the target 504 dislodges or sputters material from the target 504. The sputtering rate generally increases as the density of the plasma increases. The RF power supply 536 generates a negative RF bias voltage on the substrate 532 that attracts positively ionized sputtered material to the substrate 532. The sputtered material forms a thin film of target material on the substrate 532. The magnitude of the RF bias voltage on the substrate 532 can be chosen to optimize parameters, such as sputtering rate and adhesion of the sputtered firm to the substrate 532, and to minimize damage to the substrate 532. The temperature controller 542 can regulate the temperature of the substrate 532 to avoid overheating the substrate 532. Although FIG. 9 illustrates a magnetron sputtering system, skilled artisans will appreciate that many other plasma systems can utilize methods for generating high-density plasmas using ionizational instability according to the invention. For example, the methods for generating high-density plasmas using ionizational instability according to the invention can be used to construct a plasma thruster. The method of generating a high-density plasma for a thruster is substantially the same as the method described in connection with FIG. 9 except that the plasma is accelerated through an exhaust by external fields. FIG. 10 illustrates a schematic diagram 550 of a pulsed power supply 552 that can generate multi-step voltage pulses according to the present invention. The pulsed power supply 552 includes an input voltage 554 that charges a bank of capacitors 556. A parallel bank of high-power solid state switches 558, such as insulated gate bipolar transistors (IGBTs) is coupled to a primary coil 560 of a pulse transformer 562. The solid state switches 558 release energy stored in the capacitors 556 to the primary coil 560 of the pulse transformer 562. The pulse transformer 562 also includes a secondary coil 564. The voltage gain from the pulse transformer 562 is proportional to the number of secondary turns in the secondary coil 564. A first end 566 of the secondary coil 564 is coupled to an array of driving circuits 568. A second end 570 of the secondary coil 564 is coupled to ground 572. The array of driving circuits 568 provide voltage pulses across a first output 574 and a second output 576. The first output 574 can be coupled to a cathode and the second output 576 can be coupled to an anode. The pulsed power supply 552 can provide pulse power up to about 10 MW with a relatively fast rise time. FIG. 11 illustrates a schematic diagram 600 of a pulsed power supply 602 having a magnetic compression network 604 for supplying high-power pulses. The pulsed power supply 602 generates a long pulse with a switch and applies the pulse to an input stage of a multi-stage magnetic compression network 604. Each stage of magnetic compression reduces the time duration of the pulse, thereby increasing the power of the pulse. The pulsed power supply 602 includes a DC supply 606, a capacitor 608, and a power-MOS solid switch 610 for providing power to the magnetic compression network 604. The magnetic compression network 604 includes four non-linear magnetic inductors 612, 614, 616, 618 and four capacitors 620, 622, 624, 626. The non-linear magnetic inductors 612, 614, 616, 618 behave as switches that are off when they are unsaturated and on when they are saturated. The magnetic compression network 604 also includes a transformer 628. When the solid switch 610 is activated, the capacitor 620 begins to charge and the voltage V1 increases. At a predetermined value of the voltage V1, the magnetic core of the non-linear magnetic inductor 612 saturates and the inductance of the non-linear magnetic inductor 612 becomes low causing the non-linear magnetic inductor 612 to turn on. This results in charge transferring from the capacitor 608 to the capacitor 620. The electric charge stored in the capacitor 620 is then transferred through the transformer 628 to the capacitor 622 and so on. The charge that is transferred to the capacitor 626 is eventually discharged through a load 630. The magnetic compression network 604 can generate high-power pulses up to a terawatt in tens of nanoseconds with a relatively high repetition rate. FIG. 12 illustrates a schematic diagram 650 of a pulsed power supply 652 having a Blumlein generator 654 for supplying high-power pulses. The pulsed power supply 652 having the Blumlein generator 654 can deliver short duration high voltage pulses with a fast rise time and a relatively flat top. The pulsed power supply 652 includes a high voltage DC supply 656. A first terminal 658 of the high voltage DC supply 656 is coupled through a current-limiting inductor 660 to a dielectric material 662 that is located between an inner conductor 664 and an outer conductor 666 of a coaxial cable 668. The inner conductor 664 is coupled to ground 670 through an inductance 672. The outer conductor 666 is also coupled to ground 670. In operation, the high voltage power supply 656 slowly charges the Blumlein generator 654. A very fast high-power switch 674 discharges the charge through a load 676, such as a plasma load. FIG. 13 illustrates a schematic diagram 700 of a pulsed power supply 702 having a pulse cascade generator 704 for supplying high-power pulses. A high frequency power supply 706 is coupled to a transformer 708. The transformer 708 is coupled to a cascade of lower voltage (1 kV to 3 kV) pulse generators 710 that are connected in series. In operation, the high frequency power supply 706 charges capacitors 712 in each of the pulse generators 710. Switches 714 in each of the pulse generators 710 close at predetermined times thereby discharging energy in the capacitors 712. When the required output voltage appears between the terminal 716 and ground 718, the stored energy discharges through a load 720, such as a plasma load. EQUIVALENTS While the invention has been particularly shown and described with reference to specific preferred embodiments, it should be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined herein.

<SOH> BACKGROUND OF INVENTION <EOH>A plasma can be created in a chamber by igniting a direct current (DC) electrical discharge between two electrodes in the presence of a feed gas. The electrical discharge generates electrons in the feed gas that ionize atoms thereby creating the plasma. The electrons in the plasma provide a path for an electric current to pass through the plasma. The energy supplied to the plasma must be relatively high for applications, such as magnetron plasma sputtering. Applying high electrical currents through a plasma can result in overheating the electrodes as well as overheating the work piece in the chamber. Complex cooling mechanisms can be used to cool the electrodes and the work piece. However, the cooling can cause temperature gradients in the chamber. These temperature gradients can cause non-uniformities in the plasma density which can cause non-uniform plasma process. Temperature gradients can be reduced by pulsing DC power to the electrodes. Pulsing the DC power can allow the use of lower average power. This results in a lower temperature plasma process. However, pulsed DC power systems are prone to arcing at plasma ignition and plasma termination, especially when working with high-power pulses. Arcing can result in the release of undesirable particles in the chamber that can contaminate the work piece. Plasma density in known plasma systems is typically increased by increasing the electrode voltage. The increased electrode voltage increases the discharge current and thus the plasma density. However, the electrode voltage is limited in many applications because high electrode voltages can effect the properties of films being deposited or etched. In addition, high electrode voltages can also cause arcing which can damage the electrode and contaminate the work piece.

<SOH> BRIEF DESCRIPTION OF DRAWINGS <EOH>This invention is described with particularity in the detailed description and claims. The above and further advantages of this invention may be better understood by referring to the following description in conjunction with the accompanying drawings, in which like numerals indicate like structural elements and features in various figures. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. FIG. 1 illustrates a cross-sectional view of a plasma sputtering apparatus having a pulsed direct current (DC) power supply according to one embodiment of the invention. FIG. 2 is measured data of discharge voltage as a function of discharge current for a prior art low-current plasma and a high-current plasma according to the present invention. FIG. 3 is measured data of a particular voltage pulse generated by the pulsed power supply of FIG. 1 operating in a low-power voltage mode. FIG. 4 is measured data of a multi-stage voltage pulse that is generated by the pulsed power supply of FIG. 1 that creates a strongly-ionized plasma according to the present invention. FIG. 5A - FIG. 5C are measured data of other illustrative multi-stage voltage pulses generated by the pulsed power supply of FIG. 1 . FIG. 6A and FIG. 6B are measured data of multi-stage voltage pulses generated by the pulsed power supply of FIG. 1 that illustrate the effect of pulse duration in the transient stage of the pulse on the plasma discharge current. FIG. 7A and FIG. 7B are measured data of multi-stage voltage pulses generated by the pulsed power supply of FIG. 1 that show the effect of the pulsed power supply operating mode on the plasma discharge current. FIG. 8 is measured data for an exemplary single-stage voltage pulse generated by the pulsed power supply of FIG. 1 that produces a high-density plasma according to the invention that is useful for high-deposition rate sputtering. FIG. 9 illustrates a cross-sectional view of a plasma sputtering apparatus having a pulsed direct current (DC) power supply according to another embodiment of the invention. FIG. 10 illustrates a schematic diagram of a pulsed power supply that can generate multi-step voltage pulses according to the present invention. FIG. 11 illustrates a schematic diagram of a pulsed power supply having a magnetic compression network for supplying high-power pulses. FIG. 12 illustrates a schematic diagram of a pulsed power supply having a Blumlein generator for supplying high-power pulses. FIG. 13 illustrates a schematic diagram of a pulsed power supply having a pulse cascade generator for supplying high-power pulses. detailed-description description="Detailed Description" end="lead"?

20040222

20060822

20050825

71956.0

LIE, ANGELA M

METHODS AND APPARATUS FOR GENERATING STRONGLY-IONIZED PLASMAS WITH IONIZATIONAL INSTABILITIES

SMALL

ACCEPTED

ACCEPTED

Low-to-high level shifter

A low-to-high level shifter operating under a first supply voltage is disclosed. The low-to-high level shifter includes a pull-down circuit coupled to an input signal, the pull-down circuit having a plurality of low-voltage devices, the input signal corresponding to a second supply voltage; and a pull-up circuit coupled to the pull-down circuit, the pull-up circuit having a plurality of high-voltage devices. The low-to-high level shifter generates an output signal according to the input signal, the output signal corresponds to the first supply voltage, and the first supply voltage is larger than the second supply voltage.

1. A low-to-high level shifter operating under a first supply voltage, the low-to-high level shifter comprising: a pull-down circuit coupled to an input signal, the input signal corresponding to a second supply voltage; a pull-up circuit coupled to the pull-down circuit; and a clamping circuit coupled to the pull-down circuit, for clamping an operating voltage of the pull-down circuit; wherein the low-to-high level shifter generates an output signal according to the input signal, the output signal corresponds to the first supply voltage, and the first supply voltage is larger than the second supply voltage. 2. The low-to-high level shifter of claim 1 wherein the pull-down circuit comprises a plurality of low-voltage devices, and the pull-up circuit comprises a plurality of high-voltage devices. 3. The low-to-high level shifter of claim 2 wherein the low-voltage devices have a lower turn-on characteristic than the high-voltage devices. 4. The low-to-high level shifter of claim 1 wherein the pull-down circuit comprises a first pull-down transistor and a second pull-down transistor, control terminals of the first and the second pull-down transistors are coupled to the input signal. 5. The low-to-high level shifter of claim 1 wherein the pull-up circuit comprises a first pull-up transistor and a second pull-up transistor, a control terminal of the first pull-up transistor is coupled to a first terminal of the second pull-up transistor, and a control terminal of the second pull-up transistor is coupled to a first terminal of the first pull-up transistor. 6. The low-to-high level shifter of claim 5 wherein the output signal is extracted from the first terminal of the first pull-up transistor. 7. The low-to-high level shifter of claim 5 wherein the first terminals of the first and the second pull-up transistors are coupled to the pull-down circuit. 8. The low-to-high level shifter of claim 1 wherein the clamping circuit comprises a first clamping transistor and a second clamping transistor, control terminals of the first and the second clamping transistors are coupled to a bias voltage. 9. The low-to-high level shifter of claim 1 wherein the input signal is coupled to the pull-down circuit via an inverter operating under the second supply voltage. 10. A low-to-high level shifter operating under a first supply voltage, the low-to-high level shifter comprising: a pull-down circuit coupled to an input signal, the pull-down circuit comprising a plurality of low-voltage devices, the input signal corresponding to a second supply voltage; and a pull-up circuit coupled to the pull-down circuit, the pull-up circuit comprising a plurality of high-voltage devices; wherein the low-to-high level shifter generates an out-put signal according to the input signal, the output signal corresponds to the first supply voltage, and the first supply voltage is larger than the second supply voltage. 11. The low-to-high level shifter of claim 10 further comprising: a clamping circuit coupled to the pull-down circuit, for clamping an operating voltage of the pull-down circuit. 12. The low-to-high level shifter of claim 11 wherein the clamping circuit comprises a first clamping transistor and a second clamping transistor, control terminals of the first and the second clamping transistors are coupled to a bias voltage. 13. The low-to-high level shifter of claim 10 wherein the pull-down circuit comprises a first pull-down transistor and a second pull-down transistor, control terminals of the first and the second pull-down transistors are coupled to the input signal. 14. The low-to-high level shifter of claim 10 wherein the pull-up circuit comprises a first pull-up transistor and a second pull-up transistor, a control terminal of the first pull-up transistor is coupled to a first terminal of the second pull-up transistor, and a control terminal of the second pull-up transistor is coupled to a first terminal of the first pull-up transistor. 15. The low-to-high level shifter of claim 14 wherein the output signal is extracted from the first terminal of the first pull-up transistor. 16. The low-to-high level shifter of claim 14 wherein the first terminals of the first and the second pull-up transistors are coupled to the pull-down circuit. 17. The low-to-high level shifter of claim 10 wherein the input signal is coupled to the pull-down circuit via an inverter operating under the second supply voltage. 18. The low-to-high level shifter of claim 10 wherein the low-voltage devices have a lower turn-on characteristic than the high-voltage devices.

BACKGROUND OF INVENTION 1. Field of the Invention The invention relates to a level shifter, and more particularly, to a level shifter for shifting the voltage level of a logic signal from a low operating voltage to a high operating voltage. 2. Description of the Prior Art In an integrated circuit, because of the concerns of power and integration, the operating voltage of the integrated circuit is usually smaller than the operating voltage of an external system. Take an integrated circuit using 1.2V as the operating voltages to be an example, 1.2V and 0V are used to represent logic value 1 and 0 respectively. But an external circuit usually uses higher voltage as the operating voltage than the integrated circuit. For example, the operating voltage of circuit elements on a motherboard is normally 5V or 3.3V, that is, 5V or 3.3V is used to represent logic value 1, while 0V is used to represent logic value 0. Accordingly, in an integrated circuit, a device must be set for shifting the level of a logic signal switching between 1.2V and 0V into a logic signal switching between 5V(or 3.3V) and 0V, which is termed “low-to-high level shifter” hereinafter. In an integrated circuit, a component operating at 5V/3.3V is called high-voltage element; a component operating at 1.2V is called low-voltage element. Take metal-oxide-semiconductor transistors (MOS transistor) for example, being a high-voltage element or a low-voltage element is determined by the thickness of the oxide-layer of the MOS transistor. Generally speaking, a high-voltage MOS transistor has a thicker oxide-layer than a low-voltage MOS transistor. Consequently, the threshold voltage of the high-voltage MOS transistor is higher than the threshold voltage of the low-voltage MOS transistor. Normally a high-voltage MOS transistor has a nominal threshold voltage of 0.9V. Please refer to FIG. 1, a circuit diagram of a conventional low-to-high level shifter is illustrated. The low-to-high level shifter 100 includes: a high-voltage NMOS transistor 120, a high-voltage NMOS transistor 140, a high-voltage PMOS transistor 160 and a high-voltage PMOS transistor 180. When the four transistors are turned on or off, a first output end 191 and a second output end 192 will be charged or discharged, and the goal of level shifting will be achieved as a result. Assume that in FIG. 1, VDDH=3.3V, VSSH=0V, VDDL=1.2V, VSSL=0V. When the potential of a first input signal SL1 changes from VSSL to VDDL, at first the high-voltage NMOS transistor 120 will be turned on, while the high-voltage NMOS transistor 140 will be turned off, the potential of a first output signal SH1 on the first output end 191 will become VSSH. Next, because the potential of the first output signal SH1 equals VSSH, the high-voltage PMOS transistor 180 will be turned on, in turn the potential of the second output signal SH2 on the second output end 192 will become VDDH. But with advanced technology on integrated circuit processes, the operating voltage of the integrated circuit becomes smaller and smaller. For example, an integrated circuit produced through advanced technology can have an operating voltage lower than 1.2, such as 0.9V or even lower. Under such circumstances the low-to-high level shifter 100 in FIG. 1 will probably pass logic signals wrongly. Now consider the situation when VDDL equals 1V (assume that other parameters are unchanged). When the potential of the first input signal SL1 changes from VSSL to VDDL, because VDDL is only a bit higher than the threshold voltage of the high-voltage NMOS transistor 120, the falling speed of the potential of the first output signal SH1 will be slow, in turn the raising speed of the potential of the second output signal SH2 will also be slow. The consequence is that the switching time for the integrated circuit becomes longer, the jitter problem of logic signals becomes more serious, and as a result the whole circuit becomes unreliable. If the operating frequency of the first input signal SL1 rises, the potential of the first output signal SH1 may not have enough time to switch correctly. An extreme case is that when VDDL equals 0.9V or is lower than 0.9V, when the potential at the gate of the high-voltage NMOS transistor 120 or the high-voltage NMOS transistor 140 equals VDDL, the two transistors may not be turned on, and the low-to-high level shifter can not function correctly at all. As depicted above, one problem the prior art low-to-high level shifter faces is that logic signals probably can not pass through the low-to-high level shifter correctly, when the operating voltage of the integrated circuit becomes smaller and smaller SUMMARY OF INVENTION It is therefore one of the many objectives of the claimed invention to provide a low-to-high level shifter using low-voltage elements as pull-down elements and including a clamping circuit. According to embodiments of the invention, a low-to-high level shifter operating under a first supply voltage is disclosed. The low-to-high level shifter comprises a pull-down circuit coupled to an input signal, the input signal corresponding to a second supply voltage; a pull-up circuit coupled to the pull-down circuit; and a clamping circuit coupled to the pull-down circuit, for clamping an operating voltage of the pull-down circuit. The low-to-high level shifter generates an output signal according to the input signal, the output signal corresponds to the first supply voltage, and the first supply voltage is larger than the second supply voltage. According to embodiments of the invention, a low-to-high level shifter operating under a first supply voltage is disclosed. The low-to-high level shifter comprises a pull-down circuit coupled to an input signal, the pull-down circuit comprising a plurality of low-voltage devices, the input signal corresponding to a second supply voltage; and a pull-up circuit coupled to the pull-down circuit, the pull-up circuit comprising a plurality of high-voltage devices. The low-to-high level shifter generates an output signal according to the input signal, the output signal corresponds to the first supply voltage, and the first supply voltage is larger than the second supply voltage. These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the embodiment that is illustrated in the various figures and drawings. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a circuit diagram of a conventional low-to-high level shifter. FIG. 2 is a circuit diagram of a low-to-high level shifter according to an embodiment of the present invention. DETAILED DESCRIPTION Please refer to FIG. 2, a circuit diagram of a low-to-high level shifter according to an embodiment of the present invention is illustrated. A low-to-high level shifter 400 includes a pull-down circuit, a pull-up circuit, and a clamping circuit. In this embodiment, the pull-down circuit includes a first pull-down unit, that is a low-voltage NMOS transistor 410; and a second pull-down unit, that is a low-voltage NMOS transistor 420. The pull-up circuit includes a first pull-up unit, that is a high-voltage PMOS transistor 450; and a second pull-up unit, that is a high-voltage PMOS transistor 460. The clamping circuit includes a first clamping unit, that is a high-voltage NMOS transistor 430; and a second clamping unit, that is a high-voltage NMOS transistor 440. Please note that herein MOS transistors are divided into high-voltage MOS transistors and low-voltage MOS transistors, where they have different thickness on their oxide-layer, they can operate at different voltage range, and they have different threshold voltage. In FIG. 1 the low-to-high level shifter 100 uses high-voltage elements (that is, the high-voltage NMOS transistor 120 and the high-voltage NMOS transistor 140) as pull-down elements, while in this embodiment, low-voltage elements (that is, the low-voltage NMOS transistor 410 and the low-voltage NMOS transistor 420) are used. Because low-voltage elements have lower threshold voltage than high-voltage elements (for example, the threshold voltages of high-voltage elements and low-voltage elements are 0.9V and 0.5V respectively), when VDDL is used as the gate voltage of the low-voltage NMOS transistor 410 or the low-voltage NMOS transistor 420, the channel between the drain and source of the transistor can be turned on correctly, then the potential at its drain can be discharged to VSSH very fast. It should be noted that being low voltage elements, the potential at the drain of the low-voltage NMOS transistor 410 or the low-voltage NMOS transistor 420 should not be of too high a value (such as VDDH), or the element will probably be damaged. So in this embodiment, two clamping units are used to guarantee the potential at the drain of the low-voltage NMOS transistor 410 or the low-voltage NMOS transistor 420 will not be too high to damage these low-voltage elements. The gate of the high-voltage NMOS transistor 430 couples to a bias voltage VBIAS, for making sure that the potential at the drain of the low-voltage NMOS transistor 410 will not exceed VBIAS subtracting the threshold voltage Vt of the high-voltage transistor 430. So if the maximum potential the low-voltage NMOS transistor 410 can tolerate at its drain is 1.5V, a simple design choice is to use 2.4V as VBIAS (at this time VBIAS-Vt=1.5V). The function of the high-voltage NMOS transistor 440 is similar to that of the high-voltage NMOS transistor 430. The gate of the high-voltage PMOS transistor 450 couples to a second output end 442, the drain couples to a first output end 432, and the source couples to a high-voltage bias having potential equals VDDH. The function of the high-voltage PMOS transistor 450 is to pull up the potential of the first output signal SH1 at the first output end 432 to become VDDH when the potential of the second output signal SH2 at the second output end 442 substantially equals VSSH. The function of the high-voltage PMOS transistor 460 is similar to that of the high-voltage PMOS transistor 450. Please note that although in this embodiment the gates of the high-voltage NMOS transistor 430 and the high-voltage NMOS transistor 440 use only one bias voltage VBIAS, in other embodiments these two transistors can use different bias voltages with different potentials. The way to generate the bias voltage is a design choice of the circuit designer. The low-to-high level shifter according to embodiments of the present invention uses low-voltage elements as pull-down elements, while uses clamping elements to protect the low-voltage elements. As a result, the low-to-high level shifter according to embodiments of the present invention can pass logical signals correctly even with the operating voltage of the integrated circuit becoming smaller and smaller. Those skilled in the art will readily observe that numerous modification and alternation of the device may be made while retaining the teaching of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.

<SOH> BACKGROUND OF INVENTION <EOH>1. Field of the Invention The invention relates to a level shifter, and more particularly, to a level shifter for shifting the voltage level of a logic signal from a low operating voltage to a high operating voltage. 2. Description of the Prior Art In an integrated circuit, because of the concerns of power and integration, the operating voltage of the integrated circuit is usually smaller than the operating voltage of an external system. Take an integrated circuit using 1.2V as the operating voltages to be an example, 1.2V and 0V are used to represent logic value 1 and 0 respectively. But an external circuit usually uses higher voltage as the operating voltage than the integrated circuit. For example, the operating voltage of circuit elements on a motherboard is normally 5V or 3.3V, that is, 5V or 3.3V is used to represent logic value 1, while 0V is used to represent logic value 0. Accordingly, in an integrated circuit, a device must be set for shifting the level of a logic signal switching between 1.2V and 0V into a logic signal switching between 5V(or 3.3V) and 0V, which is termed “low-to-high level shifter” hereinafter. In an integrated circuit, a component operating at 5V/3.3V is called high-voltage element; a component operating at 1.2V is called low-voltage element. Take metal-oxide-semiconductor transistors (MOS transistor) for example, being a high-voltage element or a low-voltage element is determined by the thickness of the oxide-layer of the MOS transistor. Generally speaking, a high-voltage MOS transistor has a thicker oxide-layer than a low-voltage MOS transistor. Consequently, the threshold voltage of the high-voltage MOS transistor is higher than the threshold voltage of the low-voltage MOS transistor. Normally a high-voltage MOS transistor has a nominal threshold voltage of 0.9V. Please refer to FIG. 1 , a circuit diagram of a conventional low-to-high level shifter is illustrated. The low-to-high level shifter 100 includes: a high-voltage NMOS transistor 120 , a high-voltage NMOS transistor 140 , a high-voltage PMOS transistor 160 and a high-voltage PMOS transistor 180 . When the four transistors are turned on or off, a first output end 191 and a second output end 192 will be charged or discharged, and the goal of level shifting will be achieved as a result. Assume that in FIG. 1 , VDDH=3.3V, VSSH=0V, VDDL=1.2V, VSSL=0V. When the potential of a first input signal SL 1 changes from VSSL to VDDL, at first the high-voltage NMOS transistor 120 will be turned on, while the high-voltage NMOS transistor 140 will be turned off, the potential of a first output signal SH 1 on the first output end 191 will become VSSH. Next, because the potential of the first output signal SH 1 equals VSSH, the high-voltage PMOS transistor 180 will be turned on, in turn the potential of the second output signal SH 2 on the second output end 192 will become VDDH. But with advanced technology on integrated circuit processes, the operating voltage of the integrated circuit becomes smaller and smaller. For example, an integrated circuit produced through advanced technology can have an operating voltage lower than 1.2, such as 0.9V or even lower. Under such circumstances the low-to-high level shifter 100 in FIG. 1 will probably pass logic signals wrongly. Now consider the situation when VDDL equals 1V (assume that other parameters are unchanged). When the potential of the first input signal SL 1 changes from VSSL to VDDL, because VDDL is only a bit higher than the threshold voltage of the high-voltage NMOS transistor 120 , the falling speed of the potential of the first output signal SH 1 will be slow, in turn the raising speed of the potential of the second output signal SH 2 will also be slow. The consequence is that the switching time for the integrated circuit becomes longer, the jitter problem of logic signals becomes more serious, and as a result the whole circuit becomes unreliable. If the operating frequency of the first input signal SL 1 rises, the potential of the first output signal SH 1 may not have enough time to switch correctly. An extreme case is that when VDDL equals 0.9V or is lower than 0.9V, when the potential at the gate of the high-voltage NMOS transistor 120 or the high-voltage NMOS transistor 140 equals VDDL, the two transistors may not be turned on, and the low-to-high level shifter can not function correctly at all. As depicted above, one problem the prior art low-to-high level shifter faces is that logic signals probably can not pass through the low-to-high level shifter correctly, when the operating voltage of the integrated circuit becomes smaller and smaller

<SOH> SUMMARY OF INVENTION <EOH>It is therefore one of the many objectives of the claimed invention to provide a low-to-high level shifter using low-voltage elements as pull-down elements and including a clamping circuit. According to embodiments of the invention, a low-to-high level shifter operating under a first supply voltage is disclosed. The low-to-high level shifter comprises a pull-down circuit coupled to an input signal, the input signal corresponding to a second supply voltage; a pull-up circuit coupled to the pull-down circuit; and a clamping circuit coupled to the pull-down circuit, for clamping an operating voltage of the pull-down circuit. The low-to-high level shifter generates an output signal according to the input signal, the output signal corresponds to the first supply voltage, and the first supply voltage is larger than the second supply voltage. According to embodiments of the invention, a low-to-high level shifter operating under a first supply voltage is disclosed. The low-to-high level shifter comprises a pull-down circuit coupled to an input signal, the pull-down circuit comprising a plurality of low-voltage devices, the input signal corresponding to a second supply voltage; and a pull-up circuit coupled to the pull-down circuit, the pull-up circuit comprising a plurality of high-voltage devices. The low-to-high level shifter generates an output signal according to the input signal, the output signal corresponds to the first supply voltage, and the first supply voltage is larger than the second supply voltage. These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the embodiment that is illustrated in the various figures and drawings.

20040223

20051108

20050127

66904.0

LE, DON P

LOW-TO-HIGH LEVEL SHIFTER

UNDISCOUNTED

ACCEPTED

ACCEPTED

METHOD AND APPARATUS FOR IMPROVING CYCLE TIME IN A QUAD DATA RATE SRAM DEVICE

A method for implementing a self-timed, read to write operation in a memory storage device. In an exemplary embodiment, the method includes capturing a read address during a first half of a current clock cycle, and commencing a read operation so as to read data corresponding to the captured read address onto a pair of bit lines. A write operation is commenced for the current clock cycle so as to cause write data to appear on the pair of bit lines as soon as the read data from the captured read address is amplified by a sense amplifier, wherein the write operation uses a previous write address captured during a preceding clock cycle. A current write address is captured during a second half of the current clock cycle, said current write address used for a write operation implemented during a subsequent clock cycle, wherein the write operation for the current clock cycle is timed independent of the current write address captured during said second half of the current clock cycle.

1. A method for implementing a self-timed, read to write operation in a memory storage device, the method comprising: capturing a read address during a first half of a current clock cycle; commencing a read operation so as to read data corresponding to said captured read address onto a pair of bit lines; commencing a write operation for said current clock cycle so as to cause write data to appear on said pair of bit lines as soon as said read data from said captured read address is amplified by a sense amplifier, wherein said write operation uses a previous write address captured during a preceding clock cycle; and capturing a current write address during a second half of said current clock cycle, said current write address to be used for a write operation implemented during a subsequent clock cycle; wherein said commencing a write operation for said current clock cycle is timed independent of said current write address captured during said second half of said current clock cycle. 2. The method of claim 1, further comprising: generating an internal read clock signal from a main clock signal; generating a first internal write clock signal from said main clock signal, said first internal write clock signal used for said capturing a current write address; and generating a second internal write clock signal from said main clock signal, said second internal write clock signal used for commencing a write operation for said current clock cycle; wherein said second internal write clock signal is also a delayed version of said internal read clock signal. 3. The method of claim 2, further comprising implementing sense amplifier interlock logic to enable said write operation to cause write data to appear on said pair of bit lines as soon as said read data from said captured read address is amplified by said sense amplifier. 4. The method of claim 3, wherein said sense amplifier interlock logic utilizes a mimic word line to simulate a signal delay propagated through an actual word line and bit line during said read operation. 5. The method of claim 4, wherein said sense amplifier interlock logic is used to control a pair of read bit switches configured to selectively couple said bit lines to said sense amplifier, and said sense amplifier interlock logic is further used to control a pair of write bit switches configured to selectively couple said bit lines to a write driver. 6. The method of claim 5, wherein said sense amplifier interlock logic is used to reset a subarray of the memory storage device and disable a read-operation word line prior to the start of said write operation. 7. The method of claim 6, wherein said sense amplifier interlock logic is used to reset said subarray of the memory storage device, disable a write-operation word line, and initiate a bit line precharge operation using a write margin mimic delay circuit configured to simulate the timing margin of said write operation. 8. The method of claim 6, wherein said sense amplifier interlock logic is used to control the operation of said write driver. 9. A method for implementing a self-timed, read to write protocol for a Quad Data Rate (QDR) Static Random Access Memory (SRAM) device, the method comprising: capturing a read address during a first half of a current clock cycle; commencing a read operation so as to read data corresponding to said captured read address onto a pair of bit lines; commencing a write operation for said current clock cycle so as to cause write data to appear on said pair of bit lines as soon as said read data from said captured read address is amplified by a sense amplifier, wherein said write operation uses a previous write address captured during a preceding clock cycle; and capturing, in a write address buffer, a current write address during a second half of said current clock cycle, said current write address to be used for a write operation implemented during a subsequent clock cycle; wherein said commencing a write operation for said current clock cycle is timed independent of said current write address captured during said second half of said current clock cycle. 10. The method of claim 9, further comprising: generating an internal read clock signal from a main clock signal; generating a first internal write clock signal from said main clock signal, said first internal write clock signal used for said capturing a current write address; and generating a second internal write clock signal from said main clock signal, said second internal write clock signal used for commencing a write operation for said current clock cycle; wherein said second internal write clock signal is also a delayed version of said internal read clock signal. 11. The method of claim 10, further comprising implementing sense amplifier interlock logic to enable said write operation to cause write data to appear on said pair of bit lines as soon as said read data from said captured read address is amplified by said sense amplifier. 12. The method of claim 11, wherein said sense amplifier interlock logic utilizes a mimic word line to simulate a signal delay propagated through an actual word line and bit line during said read operation. 13. The method of claim 12, wherein said sense amplifier interlock logic is used to control a pair of read bit switches configured to selectively couple said bit lines to said sense amplifier, and said sense amplifier interlock logic is further used to control a pair of write bit switches configured to selectively couple said bit lines to a write driver. 14. The method of claim 13, wherein said sense amplifier interlock logic is used to reset a subarray of the memory storage device and disable a read-operation word line prior to the start of said write operation. 15. The method of claim 14, wherein said sense amplifier interlock logic is used to reset said subarray of the memory storage device, disable a write-operation word line, and initiate a bit line precharge operation using a write margin mimic delay circuit configured to simulate the timing margin of said write operation. 16. The method of claim 14, wherein said sense amplifier interlock logic is used to control the operation of said write driver. 17. The method of claim 9, further comprising: comparing said current write address in said write address buffer with said current read address; and upon determining a match between said current read address and said current write address, fetching said read data from a write data buffer. 18. A semiconductor memory storage device, comprising: circuitry configured to capture a read address during a first half of a current clock cycle; circuitry configured to commence a read operation so as to read data corresponding to said captured read address onto a pair of bit lines; circuitry configured to commence a write operation for said current clock cycle so as to cause write data to appear on said pair of bit lines as soon as said read data from said captured read address is amplified by a sense amplifier, wherein said write operation uses a previous write address captured during a preceding clock cycle; and circuitry configured to capture a current write address during a second half of said current clock cycle, said current write address to be used for a write operation implemented during a subsequent clock cycle; wherein said write operation for said current clock cycle is timed independent of said current write address captured during said second half of said current clock cycle. 19. The memory storage device of claim 18, further comprising: circuitry configured to generate an internal read clock signal from a main clock signal; circuitry configured to generate a first internal write clock signal from said main clock signal, said first internal write clock signal used for said capturing a current write address; and circuitry configured to generate a second internal write clock signal from said main clock signal, said second internal write clock signal used for commencing a write operation for said current clock cycle; wherein said second internal write clock signal is also a delayed version of said internal read clock signal. 20. The method of claim 19, further comprising sense amplifier interlock logic configured to enable said write operation to cause write data to appear on said pair of bit lines as soon as said read data from said captured read address is amplified by said sense amplifier. 21. The memory storage device of claim 20, wherein said sense amplifier interlock logic utilizes a mimic word line to simulate a signal delay propagated through an actual word line and bit line during said read operation. 22. The memory storage device of claim 21, wherein said sense amplifier interlock logic is configured to control a pair of read bit switches configured to selectively couple said bit lines to said sense amplifier, said sense amplifier interlock logic further configured to control a pair of write bit switches configured to selectively couple said bit lines to a write driver. 23. The method of claim 22, wherein said sense amplifier interlock logic is configured to reset a subarray of the memory storage device and disable a read-operation word line prior to the start of said write operation. 24. The memory storage device of claim 23, wherein said sense amplifier interlock logic is configured to reset said subarray of the memory storage device, disable a write-operation word line, and initiate a bit line precharge operation using a write margin mimic delay circuit configured to simulate the timing margin of said write operation. 25. The memory storage device of claim 22, wherein said sense amplifier interlock logic is configured to control the operation of said write driver. 26. A Quad Data Rate (QDR) Static Random Access Memory (SRAM) device, comprising: circuitry configured to capture a read address during a first half of a current clock cycle; circuitry configured to commence a read operation so as to read data corresponding to said captured read address onto a pair of bit lines; circuitry configured to commence a write operation for said current clock cycle so as to cause write data to appear on said pair of bit lines as soon as said read data from said captured read address is amplified by a sense amplifier, wherein said write operation uses a previous write address captured during a preceding clock cycle; and circuitry configured to capture, in a write address buffer, a current write address during a second half of said current clock cycle, said current write address to be used for a write operation implemented during a subsequent clock cycle; wherein said write operation for said current clock cycle is timed independent of said current write address captured during said second half of said current clock cycle. 27. The QDR SRAM device of claim 26, further comprising: circuitry configured to generate an internal read clock signal from a main clock signal; circuitry configured to generate a first internal write clock signal from said main clock signal, said first internal write clock signal used for said capturing a current write address; and circuitry configured to generate a second internal write clock signal from said main clock signal, said second internal write clock signal used for commencing a write operation for said current clock cycle; wherein said second internal write clock signal is also a delayed version of said internal read clock signal. 28. The QDR SRAM device of claim 27, further comprising sense amplifier interlock logic configured to enable said write operation to cause write data to appear on said pair of bit lines as soon as said read data from said captured read address is amplified by said sense amplifier. 29. The QDR SRAM device of claim 28, wherein said sense amplifier interlock logic utilizes a mimic word line to simulate a signal delay propagated through an actual word line and bit line during said read operation. 30. The QDR SRAM device of claim 29, wherein said sense amplifier interlock logic is configured to control a pair of read bit switches configured to selectively couple said bit lines to said sense amplifier, said sense amplifier interlock logic further configured to control a pair of write bit switches configured to selectively couple said bit lines to a write driver. 31. The QDR SRAM device of claim 30, wherein said sense amplifier interlock logic is configured to reset a subarray of the memory storage device and disable a read-operation word line prior to the start of said write operation. 32. The QDR SRAM device of claim 31, wherein said sense amplifier interlock logic is configured to reset said subarray of the memory storage device, disable a write-operation word line, and initiate a bit line precharge operation using a write margin mimic delay circuit configured to simulate the timing margin of said write operation. 33. The QDR SRAM device of claim 30, wherein said sense amplifier interlock logic is configured to control the operation of said write driver. 34. The QDR SRAM device of claim 26, further comprising: a comparator configured to compare said current write address in said write address buffer with said current read address; and circuitry configured to fetch said read data from a write data buffer upon determination of a match between said current read address and said current write address.

BACKGROUND OF INVENTION The present invention relates generally to integrated circuit memory devices and, more particularly, to a method and apparatus for improving cycle time in a Quad Data Rate (QDR) Static Random Access Memory (SRAM) device. Quad Data Rate (QDR) SRAM devices are currently being manufactured using a high-speed CMOS fabrication process. At the heart of the QDR architecture are two separate Double Data Rate (DDR) ports to allow simultaneous access to the memory storage array. Each port is dedicated, with one performing read operations while the other performs data write operations. By allowing two-way access to the memory array at DDR signaling rates, a quad data rate (QDR) is established. A QDR SRAM system employs dual circuitry for both the address registers and logic controllers, thus allowing for the dual port architecture. While the WRITE port stores data into the memory storage array, the READ port can simultaneously retrieve data from therefrom. A single reference clock generator controls the speeds of both ports. One signal is passed to both logic controllers, resulting in a smooth flow of data. In addition, the clock generator controls the speed of the read and write data registers, providing consistent core bandwidth and operating rates. If individual timing signals were employed for each circuit, the signals could be slightly mismatched, thus resulting in a stall or crash of the memory system. In earlier generation double data rate (DDR) devices, the core operations are directly timed from only the rising edge of the reference clock signal. As each address operation is performed, only two data operations can occur. Address operations are performed only during the rising edge of the clock signal. Because only one common data bus (port) is available, simultaneous read and write operations are not available with this technology. Unfortunately, even at higher megahertz clock speeds, DDR SRAM is challenged to provide sufficient bandwidth required by today's high-speed network communications equipment. In comparison, the differences of QDR signaling versus DDR are evident. In order to facilitate a quad data rate, all data is carried by separate read and write ports. By using a DDR clock with two ports, information can be transferred at four data items per clock (assuming two operations are needed, one read and one write). However, notwithstanding the improved bandwidth provided by QDR SRAM in performing the read operation during the first half of the clock phase and the write operation during the second half of the clock phase, the maximum cycle time of the QDR SRAM is still limited since both the read and the write operations must be performed within one-half clock cycle. In essence, the SRAM performs a complete read and precharge, then a complete write and precharge, all within the same clock cycle. Accordingly, it would be desirable to implement even further improvements in the cycle time of a QDR SRAM device, such as those used in high bandwidth applications like networking and communications systems. SUMMARY OF INVENTION The foregoing discussed drawbacks and deficiencies of the prior art are overcome or alleviated by a method for implementing a self-timed, read to write operation in a memory storage device. In an exemplary embodiment, the method includes capturing a read address during a first half of a current clock cycle, and commencing a read operation so as to read data corresponding to the captured read address onto a pair of bit lines. A write operation is commenced for the current clock cycle so as to cause write data to appear on the pair of bit lines as soon as the read data from the captured read address is amplified by a sense amplifier, wherein the write operation uses a previous write address captured during a preceding clock cycle. A current write address is captured during a second half of the current clock cycle, said current write address used for a write operation implemented during a subsequent clock cycle, wherein the write operation for the current clock cycle is timed independent of the current write address captured during said second half of the current clock cycle. In another embodiment, a method for implementing a self-timed, read to write protocol for a Quad Data Rate (QDR) Static Random Access Memory (SRAM) device includes capturing a read address during a first half of a current clock cycle, and commencing a read operation so as to read data corresponding to the captured read address onto a pair of bit lines. A write operation is commenced for the current clock cycle so as to cause write data to appear on the pair of bit lines as soon as the read data from the captured read address is amplified by a sense amplifier, wherein the write operation uses a previous write address captured during a preceding clock cycle. A current write address is captured in a write address buffer during a second half of the current clock cycle, the current write address to be used for a write operation implemented during a subsequent clock cycle, wherein the write operation for the current clock cycle is timed independent of the current write address captured during the second half of the current clock cycle. BRIEF DESCRIPTION OF DRAWINGS Referring to the exemplary drawings wherein like elements are numbered alike in the several Figures: FIG. 1 is a timing diagram illustrating the operation of a conventionally configured network QDR SRAM device; FIGS. 2(a) and 2(b) are schematic diagrams of an apparatus for implementing a self-timed, read to write protocol for a QDR SRAM device, in accordance with an embodiment of the invention; FIG. 3 is a schematic diagram illustrating the read to write interlock portion of the apparatus shown in FIG. 2(a); and FIG. 4 is a timing diagram illustrating a simulation of the self-timed, read to write protocol, in accordance with a further embodiment of the present invention. DETAILED DESCRIPTION Disclosed herein is a method and apparatus for improving cycle time in a Quad Data Rate (QDR) Static Random Access Memory (SRAM) device, in which write addresses and data are captured and buffered to be used in a subsequent read to write cycle thus allowing the write operation to be timed immediately after the read operation. The start of the write operation does not wait until addresses and data are captured. Instead, the write address and data captured in the preceding cycle is used for the write operation of the current cycle, while the write address and data captured the current cycle is actually written in the next cycle. In a conventionally configured network QDR SRAM device, the protocols dictate a read operation during the first half of the clock cycle and a write operation during the second half of the clock cycle. For example, as illustrated in the timing diagram of FIG. 1, addresses A and B correspond to the read and write addresses, respectively. The write data for address B is input in double data rate mode on both the rising and falling edges of the clock signal. The write operation may only start as soon as the corresponding write addresses and data are captured and distributed internally, as reflected by the Internal Write Data signal in FIG. 1. During the read cycle, activation of the word line (WL) signal starts a bit line signal development as shown by the signal differential on the complement and true bit-lines BLC/BLT. Then, the sense amplifier (SA) data lines are amplified once the SET signal is activated. Following the read cycle, the write WL is decoded and the write data (DB) is written to the bit lines. In this protocol, cycle time margin is measured from the completion of the previous write cycle to the activation of the read WL for the current cycle. In the example illustrated, the 2.5 ns external cycle simulation of FIG. 1 shows a cycle time margin of only about 0.13 ns. Therefore, in accordance with an embodiment of the invention, there is disclosed a method and apparatus for improving cycle time in a QDR SRAM device. Briefly stated, an improvement in the cycle time is achieved by implementing a self-timed read to write protocol in which write addresses and data are captured and buffered during a given read to write cycle are actually written in the next read to write cycle. As such, the write operation (of data and address captured in the previous cycle) may be timed immediately after the read operation of the current cycle. This capability is realized, in part, by generating a pair of write clock signals: one write clock for capturing previous cycle write and address data, and another write clock (delayed) for launching the internal write address captured during the previous cycle. Referring generally now to FIGS. 2(a) and 2(b), there is shown a schematic diagram of one possible embodiment of an apparatus 200 for implementing a self-timed read to write protocol for a QDR SRAM device. In particular, apparatus 200 generates three self-resetting clock signals (labeled “Clkrd”, “Clkwr1”, “Clkwr2”) from read/write commands, as well as a system clock (labeled “Clock”). The signals Clkrd and Clkwr1 are used to capture read and write addresses from rising and falling edges of Clock, respectively. In addition, Clkrd is also used to generate internal true and complement data addresses. Clkwr2 is a delayed version of Clkrd that is used to launch the internal write address from the current buffered write address (i.e., the earlier write-cycle address) previously captured by Clkwr1. It will be appreciated that the Clkwr2 timing is not critical, since the precise timing between read and write cycles in a given array (or subarray) is locally controlled therein. As described in further detail hereinafter, a read to write interlock 202 includes sense amplifier interlock logic used to drive a set signal to the array sense amplifiers for a read operation, to isolate the sense amplifier from the bit lines through a pair of read bit switches, to enable a subarray (including word line) reset operation, and to enable a write activate signal that activates a pair of write bit switches for beginning the write operation. As shown in FIG. 2(b), address compare logic 204 is used to fetch read data directly from a write data buffer, rather from than the array itself, whenever data from the address to be read has not yet been written to memory. Thus, the read address (Radd) and the write address (Wadd) are compared with one another on every write cycle, wherein a signal (Match) is generated if the two addresses are equal. FIG. 3 is a schematic diagram illustrating the read to write interlock 202 shown in FIG. 2(a). As is shown, signals “Subd”, “We”, “Re”and “Bitd” are subarray-decode, write, read and bit-decode pulse input controls signals to the subarray, which is accessed through a plurality of local word line drivers 302. For a selected subarray, the signal “Subsel” disables the bit line restore (i.e., precharging) devices through the signal labeled “BLrst”, and also enables the individual word lines (e.g., WL0 . . . WL255) and read bit switches (through signal RBS). In addition, through the use of a mimic (i.e., dummy) word line (WLM) and bit line (BLM), a signal sent therethrough is capable of tracking the delay through an actual word line and bit line. Moreover, WLM/BLM is also used to time the bit line signal development to as to ensure an adequate signal development at the sense amplifier. As indicated earlier, the sense amplifier interlock logic 304 includes four functions: driving the SET signal to the sense amplifier(s) 306; disabling the read bit switches (through signal RBS) in order to isolate the sense amplifier from the bit lines; enabling a subarray reset (including read word line reset); and enabling signal WRT to activate a pair of write bit switches (activated by signal WBS) to start the write operation. Once the write operation begins, a Write Margin Mimic Delay circuit 308 times the duration of the write operation. The mimic delay circuit 308 provides a more precise timing of the write to the cell, as compared to the previous approach of using a read mimic bit line delay. The end of the write operation occurs when the mimic delay circuit disables signal WBS, enables precharging signal BLrst, and regenerates a second “Subrst” pulse that restores the write word line. Thus, the subarray timings are restored twice: first at the setting of the sense amplifier, and then again at the end of the write duration pulse. FIG. 4 is a timing diagram illustrating a simulation of the self-timed, read to write protocol, in accordance with a further embodiment of the present invention. At the first rising edge of the main clock, the read portion of the read to write cycle commences. Internally, it is noted the write operation for the previous half-cycle is finishing up, as reflected by the deactivation of the previously addressed word line (signals WL, Wact go from high to low), and the deactivation of the write bit switches (WBS also goes low) to decouple the bit line pair from the write driver. In addition, the fully developed data signal on the bit lines BLC/BLT disappears as the voltage on both is restored to the precharge value of VDD. At some point during the read half-cycle, the internally generated read clock signal Clkrd (from FIG. 2(a)) goes high to capture the read data and address for the current cycle. Once the addressed wordline signal (WL) is activated by going high and the read bit switches are activated (by RBS going low), an appropriate signal development takes place on the bit line pair BLC/BLT which will then be set and driven to the full swing value by the sense amplifier. It will also be noted, however, that at about the same point in time as the word line signal goes high for the read operation, the internally generated clock signal Clkwr2 (the delayed version of Clkrd) is activated to begin the write operation immediately after the sense amplifier captures the read data. Again, the write operation for a given cycle does not depend upon waiting to capture write data and address information during the second half of the current clock cycle, because such information was already captured in the prior cycle. Thus, Clkwr2 is generated from Clkrd to launch the previously captured write address after the current read address is launched. The active low signal on the mimic bit line (BLM) activates write activation signal Wact, which in turn enables signal WBS for immediate writing of the write data (DZ) onto the bit line pair. There is no need to precharge the bit line pair once the read data is captured by the sense amplifier BL restore after the read operation; as can be seen in FIG. 4, once the read word line signal is reset and the read bit switches are disabled (RBS goes high), the bit line pair is driven by write data. Finally, after the execution of the write margin mimic delay (i.e., the falling edge of signal Wact) the write bit switches are uncoupled, the write word line is restored and the bit lines BLC/BLT are precharged. As will be appreciated, the cycle time margin achieved in the simulation of FIG. 4 is about 0.7 ns, which is a significant improvement over 0.13 ns in the conventional scheme of FIG. 1. Given a 2.5 ns external cycle, then, a cycle time margin of 0.7 ns allows the external cycle time to be reduced to about 1.8 ns. While the invention has been described with reference to a preferred embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

<SOH> BACKGROUND OF INVENTION <EOH>The present invention relates generally to integrated circuit memory devices and, more particularly, to a method and apparatus for improving cycle time in a Quad Data Rate (QDR) Static Random Access Memory (SRAM) device. Quad Data Rate (QDR) SRAM devices are currently being manufactured using a high-speed CMOS fabrication process. At the heart of the QDR architecture are two separate Double Data Rate (DDR) ports to allow simultaneous access to the memory storage array. Each port is dedicated, with one performing read operations while the other performs data write operations. By allowing two-way access to the memory array at DDR signaling rates, a quad data rate (QDR) is established. A QDR SRAM system employs dual circuitry for both the address registers and logic controllers, thus allowing for the dual port architecture. While the WRITE port stores data into the memory storage array, the READ port can simultaneously retrieve data from therefrom. A single reference clock generator controls the speeds of both ports. One signal is passed to both logic controllers, resulting in a smooth flow of data. In addition, the clock generator controls the speed of the read and write data registers, providing consistent core bandwidth and operating rates. If individual timing signals were employed for each circuit, the signals could be slightly mismatched, thus resulting in a stall or crash of the memory system. In earlier generation double data rate (DDR) devices, the core operations are directly timed from only the rising edge of the reference clock signal. As each address operation is performed, only two data operations can occur. Address operations are performed only during the rising edge of the clock signal. Because only one common data bus (port) is available, simultaneous read and write operations are not available with this technology. Unfortunately, even at higher megahertz clock speeds, DDR SRAM is challenged to provide sufficient bandwidth required by today's high-speed network communications equipment. In comparison, the differences of QDR signaling versus DDR are evident. In order to facilitate a quad data rate, all data is carried by separate read and write ports. By using a DDR clock with two ports, information can be transferred at four data items per clock (assuming two operations are needed, one read and one write). However, notwithstanding the improved bandwidth provided by QDR SRAM in performing the read operation during the first half of the clock phase and the write operation during the second half of the clock phase, the maximum cycle time of the QDR SRAM is still limited since both the read and the write operations must be performed within one-half clock cycle. In essence, the SRAM performs a complete read and precharge, then a complete write and precharge, all within the same clock cycle. Accordingly, it would be desirable to implement even further improvements in the cycle time of a QDR SRAM device, such as those used in high bandwidth applications like networking and communications systems.

<SOH> SUMMARY OF INVENTION <EOH>The foregoing discussed drawbacks and deficiencies of the prior art are overcome or alleviated by a method for implementing a self-timed, read to write operation in a memory storage device. In an exemplary embodiment, the method includes capturing a read address during a first half of a current clock cycle, and commencing a read operation so as to read data corresponding to the captured read address onto a pair of bit lines. A write operation is commenced for the current clock cycle so as to cause write data to appear on the pair of bit lines as soon as the read data from the captured read address is amplified by a sense amplifier, wherein the write operation uses a previous write address captured during a preceding clock cycle. A current write address is captured during a second half of the current clock cycle, said current write address used for a write operation implemented during a subsequent clock cycle, wherein the write operation for the current clock cycle is timed independent of the current write address captured during said second half of the current clock cycle. In another embodiment, a method for implementing a self-timed, read to write protocol for a Quad Data Rate (QDR) Static Random Access Memory (SRAM) device includes capturing a read address during a first half of a current clock cycle, and commencing a read operation so as to read data corresponding to the captured read address onto a pair of bit lines. A write operation is commenced for the current clock cycle so as to cause write data to appear on the pair of bit lines as soon as the read data from the captured read address is amplified by a sense amplifier, wherein the write operation uses a previous write address captured during a preceding clock cycle. A current write address is captured in a write address buffer during a second half of the current clock cycle, the current write address to be used for a write operation implemented during a subsequent clock cycle, wherein the write operation for the current clock cycle is timed independent of the current write address captured during the second half of the current clock cycle.

20040227

20051122

20050901

94785.0

PHUNG, ANH K

METHOD AND APPARATUS FOR IMPROVING CYCLE TIME IN A QUAD DATA RATE SRAM DEVICE

UNDISCOUNTED

ACCEPTED

ACCEPTED

Data Cartridge Library

The present invention is directed to a data cartridge library that, in one embodiment, is comprised of: (a) a frame or cabinet that defines an interior space; (b) a magazine; (c) a drive bay; (d) a picker; (e) an elevator for moving the picker; and (f) a robotics module that can be removed from the interior of the frame and is comprised of the picker and a substantial portion of the elevator.

1. A data cartridge library comprising: a frame that defines an interior space; a data cartridge magazine, operatively attached to said frame and located within said interior space, for providing a plurality of data cartridge storage spaces; a drive, operatively attached to said frame and located within said interior space, for writing data onto a recording medium located within a data cartridge and/or reading data from a recording medium located within a data cartridge; a picker that is capable of grasping a data cartridge, releasing a grasped data cartridge, inserting a grasped data cartridge into a data cartridge storage space in said data cartridge magazine, inserting a grasped data cartridge into said drive, retracting a grasped data cartridge from a data cartridge storage space in said data cartridge magazine, and retracting a grasped data cartridge from said drive; an elevator for moving said picker such that said picker can perform grasping, retracting and inserting operations in the moving of a data cartridge between any one of said data cartridge storage spaces and said drive; and a transport support structure; wherein said elevator is operatively connected to said transport support structure; wherein said picker is operatively connected to said elevator; a user-actuatable connector that allows a user: (a) to attach a transport module comprising said transport support structure, at least a portion of said elevator, and said picker to said frame; and (b) to detach said transport module from said frame. 2. A data cartridge library, as claimed in claim 1, wherein: said frame comprises an exterior surface; and a portion of said exterior surface is capable of being displaced by a user so as create an opening with sufficient dimensions to allow said transport module to be inserted into and removed from said interior space. 3. A data cartridge library, as claimed in claim 1, wherein: said user-actuatable connector comprises: a first connector portion that is operatively associated with said frame; and a second connector portion that is operatively associated with said transport support structure. 4. A data cartridge library, as claimed in claim 3, wherein: said first connector portion comprises a flange. 5. A data cartridge library, as claimed in claim 3, wherein: said first connector portion comprises a plurality of flanges. 6. A data cartridge library, as claimed in claim 3, wherein: said second portion comprises a screw. 7. A data cartridge library, as claimed in claim 3, wherein: said second portion comprises a captured screw. 8. A data cartridge library, as claimed in claim 1, wherein: said transport module comprises an electric motor of said elevator. 9. A data cartridge library, as claimed in claim 1, wherein: said transport module comprises first and second electrical motors of said elevator. 10. A data cartridge library, as claimed in claim 1, wherein: said transport module comprises an elevator carriage that supports said picker. 11. A data cartridge library, as claimed in claim 1, wherein: said transport module comprises a controller. 12. A data cartridge library, as claimed in claim 1, wherein: said elevator comprises: an electric motor; an elevator carriage have a first end and a second end that is separated from said first end; a first drive system for applying a force to said first end of said elevator carriage; and a second drive system for applying a force to said second end of said elevator carriage. 13. A data cartridge library, as claimed in claim 12, wherein: said transport module comprises said first drive system. 14. A data cartridge library, as claimed in claim 13, wherein: said transport module comprises said electric motor. 15. A data cartridge library, as claimed in claim 13, wherein: said transport module comprises said elevator carriage. 16. A data cartridge library, as claimed in claim 1, wherein: said elevator comprises: an electric motor; an elevator carriage comprising a first end and a second end that is separated from said first end; a first drive system for applying a force to said first end of said elevator carriage; a second drive system for applying a force to said second end of said elevator carriage; and a shaft for transferring a force from said first drive system to said second drive system. 17. A data cartridge library, as claimed in claim 16, wherein: said transport module comprises a portion of said shaft that is less than all of said shaft 18. A data cartridge library, as claimed in claim 17, wherein: said portion of said shaft comprises a portion of a connector for connecting said portion of said shaft to another portion of said shaft. 19. A data cartridge library, as claimed in claim 17, wherein: said portion of a connector comprises a spline. 20. A data cartridge library, as claimed in claim 1, wherein: said elevator comprises an elevator carriage comprising a first end and a second end that is separated from said first end; wherein said first end of said elevator is operatively attached to said transport support structure; wherein said elevator further comprises a portion of a connector that allows a user to attach or detach said second end of said elevator from said frame.

FIELD OF THE INVENTION The present invention is directed to a data cartridge library that is useful in storing data on a recording medium located in a cartridge and/or retrieving data from a recording medium located in a cartridge. BACKGROUND OF THE INVENTION Presently, data cartridge libraries are primarily used to archive data, i.e., store data that is not immediately needed by a host computer, and provide archived data to the host computer when the data is needed. To elaborate, the typical data cartridge library receives data from a host computer and causes the data to be stored or recorded on the recording medium located in one or more cartridges. When the host computer requires some of the data that was previously stored in a data cartridge, a request for the data is sent from the host computer to the library. In response, the library identifies the data cartridge(s) in which the desired data is located, retrieves the data from the recording medium with the cartridge(s), and transmits the retrieved data to the host computer system. Presently, most data cartridge libraries are comprised of: (a) a frame/chassis/cabinet that defines an interior space; (b) a magazine structure that is located within the interior space and that provides a plurality of data cartridge storage spaces, which are each capable of accommodating at least one data cartridge; (c) one or more drives that are each located within the interior space and capable of writing data onto a recording medium located in a data cartridge and/or reading data from the recording medium located in a data cartridge; (d) a data cartridge transport device that is located within the interior space and capable of moving an individual data cartridge between any one of the plurality of data cartridge storage spaces and any one of the drives within the library; and (e) an interface for receiving data from and transmitting data to a host computer. Typically, such a data cartridge library is capable of both storing data provided by a host computer and retrieving data previously stored in the library for the host computer. The storage of data involves using the transport device to move a data cartridge from one of the data cartridge storage spaces to a drive, using the drive to write the data provided by the host computer on the recording medium located within the cartridge, and after the data has been written on the recording medium, using the transport device to move the data cartridge from the drive to a data cartridge storage space. The retrieval of data involves using the transport device to move a data cartridge from one of the data cartridge storage spaces to a drive, using the drive to read the data on the recording medium located within the cartridge and provide the read data to the host computer, and after the data has been read from the recording medium, using the transport device to move the data cartridge from the drive to a data cartridge storage space. As previously noted, a data cartridge library is comprised of a data cartridge transport that is capable of being used to move a data cartridge between any one of the magazine data cartridge storage locations and any one of the drives in the library. Typically, the data cartridge transport device is comprised of a picker and an elevator that moves the picker within the interior space. The picker is capable of inserting/extracting a data cartridge into/from any one of the magazine storage spaces and any one of the drives. Typically, the picker is comprised of: (a) a grasping device that is used to engage a data cartridge and (b) a pusher plate that carries the grasping device and that is capable of movement towards and away from a location that is capable of accommodating a data cartridge. The elevator serves to position the picker adjacent to a location that is capable of accommodating a data cartridge so that the picker can perform an insertion or extraction operation. In an extraction operation, the elevator is used to position the picker adjacent to a space at which a data cartridge is located (typically, either a storage space associated with the magazine or a drive). After the picker has been positioned, the pusher plate is used to move the grasping device towards the data cartridge. After the grasping device has been positioned, the grasping device is then actuated to grasp the cartridge. At this point, the pusher plate is then moved away from the location at which the data cartridge was located to extract the data cartridge from the space. In an insertion operation, the elevator is used to position the picker (which is assumed to be grasping a data cartridge) adjacent to the space at which a data cartridge is to be located. After the picker has been positioned, the pusher plate is then used to move the grasping device and the grasped data cartridge towards the space in which the data cartridge is to be located. After the pusher plate and grasping device have positioned the data cartridge in the space, the grasping device releases the data cartridge, and the pusher plate is moved away from the space to retract the grasping device. Many data cartridge libraries are also comprised of an entry/exit port that allows a user to insert and/or extract a data cartridge from the library without powering down the transport device. To elaborate, absent an entry/exit port, if a user wants to insert/extract a data cartridge into/from a library, the user typically powers down the transport device to avoid being injured by the transport device during the insertion or extraction of the data cartridge. The entry/exit port allows a user to insert/extract a data cartridge into/from the library without being exposed to the transport device. As a consequence, the entry/exit port allows a data cartridge to be inserted/extracted into/from the library without having to power down the transport device. Typically, an entry exit port is comprised of a slot structure that defines at least one slot that is capable of accommodating at least one data cartridge and a device that places the structure in one of two states. In the first state, the device positions the slot structure such that a slot is exposed to the exterior environment. When the structure is in this state, a user can either insert a data cartridge into the slot or remove a data cartridge from the slot, without being exposed to the transport device in either case. In the second state, the device positions the slot structure such that a slot is exposed to the interior of the library and accessible by the transport device, which can either insert a cartridge into the slot or remove a cartridge from the slot. When the structure is in the second state, the user is not exposed to the transport device. One type of entry/exit port that has evolved is comprised of: (a) a frame or support to/from which a magazine that can accommodate multiple data cartridges can be attached/detached; and (b) a device for placing the frame in one of the states. In the first state, the device positions the frame such that the frame is exposed to the exterior environment. When the structure is in this state, a user can either attach a magazine to the frame or detach a magazine from the frame. Further, the user can either insert/remove one or more data cartridges into/from the magazine. In the second state, the device positions the frame such that any magazine that is attached to the frame is exposed to the transport device. In this state, the transport device can load data cartridges into the magazine or remove data cartridges from the magazine, as needed. When the frame is in either state, a user is substantially shielded from the transport device. Many data cartridge libraries also have a hinged door that allows a user access to the interior of the library. Typically, such a door is provided so that the transport device can be accessed for maintenance and repair. SUMMARY OF THE INVENTION The present invention is directed to a data cartridge library that is comprised of: (a) a frame/chassis/cabinet; (b) a data cartridge magazine that provides a plurality of data cartridge storage spaces that are each capable of accommodating at least one data cartridge; (c) a drive that is capable of writing data onto a recording medium located within a cartridge and/or reading data from a recording medium located in a cartridge; (d) a picker that is capable of being used to insert and extract a data cartridge from a space that is capable of accommodating a data cartridge; and (e) an elevator for moving the picker within the library so that a data cartridge can be transported between any one of the plurality of magazine data cartridge storage spaces and any one of the drives within the library. In one embodiment, the data cartridge library comprises a picker that is comprised of: (a) a base plate that is operatively connected to an elevator; (b) a grasper that is operatively connected to the base plate and comprised of a pair of members that are capable of being placed in a closed position that is suitable for grasping a data cartridge and an open position that is suitable for releasing a grasped data cartridge; and (c) a crank that is operatively connected to the base plate and capable of rotating about an axis. The picker further comprises a grasper cam structure comprised of a cam driver that is associated with the crank and a cam follower that is associated with the grasper. The cam driver and the cam follower are situated such that rotation of the crank brings the cam driver into contact with the cam follower and, in so doing, places the grasper in one of the closed position and the open position. Unlike known pickers that employ a crank and a cam structure to actuate a grasper, the grasper is placed in a closed position over a first range of rotation of the crank and an open position over a second range of rotation of the crank that substantially does not overlap with the first range of rotation. In one embodiment, the first and second ranges are each about 180 degrees. In one embodiment, the data cartridge library comprises a picker that is comprised of: (a) a base plate that is operatively connected to an elevator; (b) a grasper that is operatively connected to the base plate and comprised of a pair of members that are capable of being placed in a closed position that is suitable for grasping a data cartridge and an open position that is suitable for releasing a grasped data cartridge; and (c) a crank that is operatively connected to the base plate and capable of rotating about an axis. The picker further comprises a grasper cam structure comprised of a cam driver that is associated with the crank and a cam follower that is associated with the grasper. The cam driver and the cam follower are situated such that rotation of the crank brings the cam driver into contact with the cam follower and, in so doing, places the grasper in one of the closed position and the open position. Unlike known pickers that employ a crank and a cam structure to actuate a grasper, the crank is capable of rotating through more than 180 degrees. In one embodiment, the crank is capable of rotating through 360 degrees. In a particular embodiment in which the crank is capable of such a rotation, the picker is further comprised of a pusher plate that supports the grasper and a pusher plate cam structure that is used to move the pusher plate towards and away from a space that is capable of accommodating a data cartridge. The pusher plate cam structure is comprised of a pusher plate cam driver that is associated with the crank and a pusher plate cam follower that is associated with the pusher plate. The grasper cam structure and pusher cam structure are situated such that: (a) for 180 degrees of a 360 degree rotation of the crank, the grasper is placed in a closed position and the pusher plate can be moved between a fully retracted and a fully extended position; and (b) for the other 180 degrees of a 360 degree rotation of the crank, the grasper is placed in an open position and the pusher plate can be moved between a fully retracted position and a fully extended position. In another embodiment, the data cartridge library is comprised of a picker that is, in turn, comprised of a base plate, grasper, crank that is capable of rotation about an axis, and a grasper cam structure. The grasper cam structure is comprised of a cam driver that is associated with the crank and a cam follower that is associated with the grasper. The grasper cam driver has a surface vector that is not substantially perpendicular to the axis or rotation of the crank. In one embodiment, the grasper cam driver comprises a bubble-like or spherical section that has such a surface vector. In a further embodiment, the picker is comprised of a pusher plate and a pusher plate cam structure with a pusher plate cam driver that is associated with the crank. The pusher plate cam driver has a surface vector, in contrast to the grasper cam driver, that is substantially perpendicular to the axis of rotation of the crank. In one particular embodiment, the pusher plate cam structure operates to move the pusher plate in a direction that is substantially perpendicular to the axis of rotation of the crank and the grasper cam structure operates such that the grasper cam follower is displaced in a direction that at least has a component vector that is parallel to the axis of rotation of the crank. In another embodiment, a data cartridge library is provided that allows a user to readily remove/insert a transport module from/into the library, where the transport module is comprised of a picker and a substantial portion of an elevator. In one embodiment, the library is comprised of: (a) a frame/chassis/cabinet; (b) a data cartridge magazine; (c) a drive; (d) a picker that is capable of being used to insert and extract a data cartridge from a space that is capable of accommodating a data cartridge; and (e) an elevator for moving the picker within the library so that a data cartridge can be transported between any one of the plurality of magazine data cartridge storage spaces and any one of the drives within the library. The library is further comprised of a transport module that is comprised of a support structure, a portion of the elevator that is connected to the support structure, and the picker. A user-actuatable connector is also provided that allows a user to attach the transport module to the frame of the library and to detach the transport module from the frame so that the module can be removed from the library. In one embodiment of a data cartridge library with a removable/insertable transport module, the elevator is comprised of an elevator carriage that supports the picker, a first drive system for driving one end of the carriage, a second drive system for driving the other end of the carriage, an electric motor that is operatively connected to the first drive system and provides the first drive system with energy for moving the first end of the carriage. The elevator is further comprised of a shaft that connects the first drive system to the second drive system, thereby allowing energy from the motor to be transferred through the first drive system to the second drive system. So that the transport module can be removed from the library, the shaft is capable of be separated into two pieces by actuation of a user-actuatable connector. In one embodiment, the connector is comprised of a spline associated with a free end of one piece of the shaft and a spline collar that is associated with the free end of the other piece of the shaft. By sliding the spline collar away from the spline, the two pieces of the shaft are disconnected to facilitate removal of the transport module from the library. To connect the two pieces of the shaft, the free ends of the shaft are aligned and the spline collar is slide over the spline. In yet another embodiment, a data cartridge library is provided in which a shaft, rather than a pulley system, is used to connect two drive structures that are used to drive the ends of an elevator carriage that supports a picker. In one embodiment, the library is comprised of: (a) a frame/chassis/cabinet; (b) a data cartridge magazine; (c) a drive; (d) a picker that is capable of being used to insert and extract a data cartridge from a space that is capable of accommodating a data cartridge; and (e) an elevator for moving the picker within the library so that a data cartridge can be transported between any one of the plurality of magazine data cartridge storage spaces and any one of the drives within the library. The elevator is comprised of an elevator carriage that supports the picker, a first drive system for driving one end of the carriage, a second drive system for driving the other end of the carriage, an electric motor that is operatively connected to the first drive system and provides the first drive system with energy for moving the first end of the carriage. The elevator is further comprised of a shaft that connects the first drive system to the second drive system, thereby allowing energy from the motor to be transferred through the first drive system to the second drive system. In yet another embodiment, a data cartridge library is provided with a door that allows a user access to the interior of the library and that is not constrained to rotate about an axis when moving between open and closed positions. In one embodiment, the library is comprised of: (a) a frame/chassis/cabinet with a top surface, bottom surface, and side surface extending between the top and bottom surfaces; (b) a data cartridge magazine; (c) a drive; (d) a picker that is capable of being used to insert and extract a data cartridge from a space that is capable of accommodating a data cartridge; and (e) an elevator for moving the picker within the library so that a data cartridge can be transported between any one of the plurality of magazine data cartridge storage spaces and any one of the drives within the library. The library is further comprised of a user interface that is associated with the side surface of the frame and is exposed to the exterior environment. In various embodiments, the user-interface comprises an output terminal for providing a user with information relating to the library, an input terminal for allowing a user to interact with the library, an entry/exit port, and combinations of the these elements. The side surface is comprised of a displaceable portion that accommodates the user interface. The displaceable portion is capable of being placed in an “open” condition that allows a user access to the magazine, drive(s), picker and elevator and a “closed” condition that prevents user access to the noted elements. The library further comprises a user-actuatable connector that permits a user to place the displaceable portion in either the open or closed conditions. However, unlike hinged doors, the displaceable portion and the user-actuatable connector do not constrain the displaceable portion to rotate about an axis in moving between open and closed positions. In one embodiment, the user-actuatable connector comprises one or more captured screws that allow the displaceable portion to be detached from the frame to expose the interior of the library or attached to the frame to cover the interior of the library. In another embodiment, a data cartridge library is provided that has a multi-piece magazine. In one embodiment, the library is comprised of: (a) a frame/chassis/cabinet; (b) a data cartridge magazine; (c) a drive; (d) a picker that is capable of being used to insert and extract a data cartridge from a space that is capable of accommodating a data cartridge; and (e) an elevator for moving the picker within the library so that a data cartridge can be transported between any one of the plurality of magazine data cartridge storage spaces and any one of the drives within the library. In one embodiment, the magazine is a multi-piece structure that forms a channel with a first side, a second side, and a back side that extends between the first and second sides. The first, second and back sides cooperatively define an interior space that is capable of accommodating a plurality of data cartridges. The multi-piece magazine structure is comprised of: (a) a first structure that is in the form of a U-shaped channel that forms portions of the first and second sides of the magazine and the back side of the magazine; (b) a second structure that forms portions of the first and second sides; and (c) a coupler for connecting the first and structures to one another. The first structure also serves as a portion of the frame of the library and, in one embodiment, is made of metal. The second structure is made of the same type of material as the cartridges (typically, plastic) in one embodiment. The present invention further provides a multi-piece magazine that is suitable for use in a data cartridge library. In one embodiment, the magazine resulting for the joining together of the various pieces forms a channel with a first side, a second side, and a back side that extends between the first and second sides. The first side, second side and back side cooperatively define an interior space that is capable of accommodating a plurality of data cartridges. The multi-piece magazine structure is comprised of: (a) a first structure that forms at least a portion of the back side of the magazine; (b) a second that structure that forms at least portions of the first and second sides; and (c) a coupler for connecting the first and second structures to one another. In one embodiment, the first structure is in the form of a U-shaped channel that forms portions of the first and second sides of the magazine and a substantial portion of the back side of the magazine. The second structure, in addition to providing at least portions of the first and second sides of the magazine, further comprises a pair of end sides that are separated from each other and that each connect the portions of the first and second sides provided by the second structure to one another, thereby forming a closed-loop structure. The coupler connects the first and second structures to one another so as to form a box-like, magazine structure with an open side through which cartridges can be inserted/removed into/from the magazine structure. The present invention also provides a magazine that is capable of being attached/detached to/from an entry/exit port structure. The magazine is comprised of: (a) a box structure with a bottom wall and a side wall that extends from the bottom wall to a terminal edge that defines an opening for the insertion/extraction of data cartridges into/from the magazine; (b) a plurality of partitioning structures that partition the interior space of the magazine into a plurality of slots that are each capable of accommodating at least one data cartridge; and (c) a coupling structure that allows the box structure to be attached/detached to/from an entry/exit port structure. In one embodiment, the coupling structure is comprised of a first substantially rigid flange that extends away from a first side wall portion and a second substantially rigid flange that extends away from a second side wall portion that is separated from and substantially parallel to the first side wall portion. In one embodiment, the first and second flanges are located in an asymmetric manner so that the box structure can only be mounted to the entry/exit port structure in a particular orientation. The present invention further provides a data cartridge library with an entry/exit port that has a frame that can be readily attached and detached to facilitate maintenance of the entry/exit port. In one embodiment, the library is comprised of: (a) a frame/chassis/cabinet; (b) a data cartridge magazine; (c) a drive; and (d) a transport assembly that is capable of moving a data cartridge between any one of the plurality of magazine data cartridge storage spaces and the drive. The library is further comprised of an entry/exit port for moving entry/exit port magazines between an exterior environment and an interior environment of the library where the magazine is accessible to the transport device. In one embodiment, the entry/exit port comprises a mount to which a magazine can be attached and from which a magazine can be detached, a guide structure for constraining the movement of the mount between a first position at which a user can attach/ detach a magazine to/from the mount and a second position at which the transport assembly is capable of inserting/removing a data cartridge into/from a magazine attached to the mount, and a motive device for providing the motive force for moving the mount between the first and second positions. The entry/exit port further comprises a “stop” structure that is attached to the mount and operates to prevent the mount from being moved beyond the first position. A quick release structure allows the stop structure to be quickly detached from the mount so that the mount can be readily removed from the library. The present invention also provides a data cartridge library with a drive bay that is capable of accommodating a full-height drive and being altered to accommodate two, half-height drives. In one embodiment, the library is comprised of: (a) a frame/chassis/cabinet; (b) a data cartridge magazine; and (c) a transport assembly that is capable of moving a data cartridge between any one of the plurality of magazine data cartridge storage spaces and any one of the drives within the library. The library is further comprised of a drive bay that provides a full-height drive space that is capable of accommodating a full-height drive and a partition mount for supporting a partition that allows the full-height drive space to be divided into two, half-height drive spaces that are each capable of accommodating a half-height drive. In one embodiment, the full-height drive space is capable of: (a) accommodating a full-height drive that is located within a full-height drive sled; or (b) when a partition engages the partition mount, accommodating two, half-height drives that are each located within a half-height drive sled. In other embodiments, the library is further comprised of combinations of full-height and half-height drives located in the drive bay. The present invention also provides a data cartridge library with a universal bay that is capable of accommodating one of more electronic devices that are not necessary to the operation of the library but can be used to enhance or supplement the operation of the library. In one embodiment, the library is comprised of a frame/chassis/cabinet that defines an interior space. The interior space is partitioned into: (a) a data cartridge space that provides storage locations for all of the cartridges that the library is capable of storing; (b) a drive space that provides locations for all of the drives that the library is capable of supporting; (c) a transport assembly space for accommodating the movement of a picker and elevator in moving a data cartridge between any one of the data cartridge storage locations and any one of the drives within the library; (d) a power supply space for housing all of the power supplies that the library is capable of supporting; and (e) circuitry space for housing circuitry that is used to distribute power within the library and control the operation of the transport assembly. The library is further comprised of a universal bay that defines a universal space which can be used to house circuitry other than the circuitry located in the circuitry space and does not comprise any of the other noted spaces. In one embodiment, the universal bay comprises a partition mount that is capable of supporting a partition that is used to divide the universal space into subsidiary spaces, each capable of accommodating circuitry that enhances or supplements the operation of the library. BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A-1B illustrate the exterior of an embodiment of a data cartridge library that is capable of processing LTO tape cartridges; FIG. 2 is an exploded view of the embodiment of the data cartridge library illustrated in FIGS. 1A-1B; FIGS. 3A-3B illustrates an LTO tape data cartridge; FIGS. 4A-4B illustrate a DLT tape data cartridge; FIGS. 5A-5B illustrate a displaceable portion of the side of the housing of library shown in FIGS. 1A-1B that allows a user to access the interior of the library; FIGS. 6A-6C illustrate an entry/exit port associated with the data cartridge library illustrated in FIGS. 1A-1B; FIGS. 7A-7F illustrate a cartridge magazine that can be attached/detached to/from the entry/exit port illustrated in FIGS. 6A-6C and portions of the magazine; FIGS. 8A-8E illustrate a multi-piece magazine for storing a plurality of LTO tape cartridges and that is associated with the library shown in FIGS. 1A-1B; FIGS. 9A-9F illustrate a drive bay that is associated with the library shown in FIGS. 1A-1B and capable of accommodating multiple full-height drives and be adapted to accommodate half-height drives within a space that is capable of accommodating one of the full-height drives; FIGS. 10A-10B illustrate the space within the library shown in FIGS. 1A-1B that is used to house power supplies and circuitry for distributing electrical power to various power consuming components within the library; FIGS. 11A-11C a universal bay that is associated with the library shown in FIGS. 1A-1B and capable of accommodating circuitry that enhances of supplements the operation of the library but is not necessary to the operation of the library; FIGS. 12A-12F illustrate the transport system that is associated with the library shown in FIGS. 1A-1B; FIG. 13A-13B illustrates aspects of the robotics module that can be readily inserted into and removed from the library illustrated in FIGS. 1A-1B; FIGS. 14A-14F illustrate the picker that is associated with the library shown in FIGS. 1A-1B; FIGS. 15A1-15D2 illustrate the operation of the picker in grasping an LTO tape cartridge; and FIGS. 16A-16D illustrate the ranges of rotation of the crank during which the grasper assembly is in the open position and in the closed position. DETAILED DESCRIPTION With reference to FIGS. 1A, 1B and 2, an embodiment of a data cartridge library 100 (hereinafter referred to as “library 100”) is described. Generally, the library is comprised of: (a) a frame/chassis/cabinet 102 that defines an interior space for containing the other components of the library; (b) entry/exit port 104 for moving data cartridges into and out of the library; (c) a magazine structure 106 for providing a plurality of data cartridge storage spaces that are each capable of accommodating at least one data cartridge; (d) a drive bay 108 for housing a plurality of drives; (e) a plurality of drives 110 located in a drive bay 108, with each drive capable of writing/reading data onto/from a recording medium located in a cartridge; (f) a transport system 112 for moving a data cartridge between any one of the data cartridge storage spaces provided by the magazine structure 106 and any one of the drives 108; (g) a power supply/control module bay 114 for housing at least one power supply and control circuitry that is deemed necessary to the operation of the library; (h) a pair of power supplies 116A, 116B that are each located in the power supply/control module bay 114; (g) a library control module 118 located in the power supply/control module bay 114; and (h) a universal bay 120 for housing electronic circuitry that enhances or supplements the operation of the library but is not deemed necessary to the operation of the library. Before describing the library 100 in greater detail, the data cartridges that the library 100 is adapted to manipulate are described. The library 100 is adapted for operating on magnetic tape cartridges. Specifically, the library 100 is adapted for operating on cartridges that conform to the following cartridge formats: (a) LTO (linear tape open) and (b) DLT (digital linear tape). It should, however, be appreciated that the library 100 can be adapted to operate on magnetic tape cartridge that conform to other cartridge formats, such as AIT (advanced intelligent tape), SAIT (super advanced intelligent tape), Travan, and the like. Further, it should be appreciated that the library can be adapted to operate on cartridges that contain other types of recording mediums, such as magnetic disk, optical disk and optical tape mediums. With reference to FIGS. 3A-3B, an LTO tape cartridge 130 comprises a first cartridge face 132A, a second cartridge face 132B, a first cartridge side 134A, a second cartridge side 134B, a first cartridge end 136A, and a second cartridge end 136B. The distance between the first and second cartridge faces 132A, 132B defines the height of the cartridge, which is 0.85 in. The distance between the first and second side surfaces 134A, 134B defines the width of the cartridge, which is 4.15 in. The distance between the first and second ends 136A, 136B defines the depth of the cartridge, which is 4.02 in. The cartridge further comprises an orientation feature 138 that provides a basis for properly orientating the cartridge for insertion in to an LTO tape drive so that data can be read from and/or written to the recording medium within the cartridge. The orientation feature 138 also provides a basis for orienting all of the LTO tape cartridges stored within the library 100 in the same manner. The cartridge also comprises a first pair of gripper notches 140A, 140B and a second pair of gripper notches 142A, 142B, with one or both pair of notches typically used by a device that grips the cartridge during transport between a magazine and a drive. With reference to FIGS. 4A-4B, a DLT tape cartridge 150 comprises a first cartridge face 152A, a second cartridge face 152B, a first cartridge side 154A, a second cartridge side 154B, a first cartridge end 156A, and a second cartridge end 156B. The distance between the first and second cartridge faces 152A, 152B defines the height of the cartridge, which is 1.00 in. The distance between the first and second side surfaces 154A, 154B defines the width of the cartridge, which is 4.15 in. The distance between the first and second ends 156A, 156B defines the depth of the cartridge, which is 4.16 in. The cartridge further comprises an orientation feature 158 that provides a basis for properly orientating the cartridge for insertion into a DLT tape drive so that data can be read from and/or written to the recording medium within the cartridge. The orientation feature in an actual DLT is somewhat more complex than the feature shown in FIG. 4A. The orientation feature 158 also provides a basis for orienting all of the DLT tape cartridges stored in the library 100 in the same manner. The cartridge also comprises a single gripper notch 160, which is typically used by a device that grips the cartridge during transport between a magazine and a drive. The DLT tape cartridge 150 further comprises a recess 162 in the first end 156A that is typically used for to hold a label, such as a bar-code label, that is used to identify the cartridge. Having described the tape data cartridges on which the library 100 operates, the library 100 is now described in greater detail. With reference to FIGS. 1A-1B, the library 100 comprises a front side 170A, a rear side 170B, a first lateral side 170C, a second lateral side 170D, a top side 170E, and a bottom side 170F. Associated with the front side 170A of the library 100 is the entry/exit port 104 and a power button 172 that allows a user to control the application of electrical power from the power supplies 116A, 116B to components of the library. Also associated with the front side 170A is a touch screen 172 that is used to output information relating to the library 100 to a user and to allow a user to input information (e.g., commands) to the library 100. Other types of input and output peripherals can be used in place of the touch screen 106. For instance, a screen can be provided to output information to a user and a keyboard can be provided to allow a user to input information. A front panel 176 that provides ports for accommodating the entry/exit port 104, the power button 172 and the touch screen 172 is also associated with the front side 170A. The front panel 176 is also capable of being removed by a user to allow the user to access the interior of the library 100. Associated with the rear side 170B of the library 100 is access to the space within the drive bay 108, which allows a user to insert/remove a drive into/from the drive bay 108. User access to the power supply/control module bay 114 is also associated with the rear side 170B. Specifically, a user can insert/remove a power supply and/or insert/remove a library control module via the access provided to the power supply/control module bay 114 at the rear side 170B. Also associated with the rear side 170B is access to the space within the universal bay 120. In the embodiment of the library illustrated in FIG. 1B, a pair of quad-interface processors are resident in the space defined by the universal bay 170B. The first lateral side 170C comprises a cosmetic exterior skin 178A. Underlying the skin 178A is: (a) a side portion 180A of a top tray 182, (b) a side portion 184A of a bottom tray 186, and (c) portions of the magazine structure 106 that connect the side portion 180A and the side portion 184A. The side portion 184A also accommodates a rail that facilitates rack mounting of the library 100. Similarly, the second lateral side 170D comprises a cosmetic exterior skin 178B. Underlying the skin 178B is: (a) a side portion 180B of a top tray 182, (b) a side portion 184B of a bottom tray 186, and (c) portions of the magazine structure 106 that connect the side portion 180B and the side portion 184B. The side portion 184B also accommodates a rail that facilitates rack mounting of the library 100. The top side 170E comprises a mid-portion 188 of the top tray 182 that extends between the side portions 180A, 180B. Similarly, the bottom side 170F comprises a mid-portion 190 of the bottom tray 186. The top tray 182, bottom tray 186, and the portions of the magazine structure 106 that connect the top tray 182 and the bottom tray 186 form the frame 102, i.e., the structure that supports the other elements of the library and defines an interior space in which the other elements of the library reside. It should be appreciated that other frame structures are also feasible. With reference to FIGS. 5A-5B, the removable front panel 176 is described in greater detail. Generally, the removable front panel 176 comprises a panel structure 200 and a plurality of captured screws 202, i.e. screws that can be actuated to attach/detach the front panel 176 from the remainder of the library 100 but that remain attached to the panel structure 200 to prevent loss. A plurality of threaded holes 204, each for engaging one of the captured screws 202, are associated with portions of the library other than the front panel 176. When the front panel 176 is in place, as shown in FIG. 1A, each of the captured screws 202 is accessible to a user and engages one of the threaded holes 204, thereby placing the front panel 176 in a “closed” state that prevents a user from accessing the interior of the library 100 via the opening covered by the front panel 176. If a user wants to access the interior of the library 100, the captured screws 202 are actuated to disengage the screws from the threaded holes. After all of the captured screws 202 have been disengaged from the threaded holes 204, the front panel 176 can be removed to expose the interior of the library. The opening provided by removal of the front panel 176 is sufficient to allow a transport module comprised of a picker and a substantial portion of an elevator and an associated tray to be inserted/removed into/from the interior of the library 100. The front panel 176 also defines openings 206A-206C that respectively accommodate the exit/entry port 104, the power button 172, and the touch screen 174. With reference to FIG. 5B, the front panel 176 is comprised of a sheet metal portion 208 and a plastic portion 210 that is readily attached/detached to/from the sheet metal portion 208 to expose at least some of the captured screws 202. The sheet metal portion 208 supports all of the captured screws 202. Additionally, the sheet metal portion 208 is comprised of: (a) a first screen portion 212 that allows air to flow from the exterior environment into the interior of the library to cool components located therein but prevents electro-magnetic radiation from escaping from the interior of the library; (b) a second screen portion 214 that permits a user to view the interior of the library when the front panel is in the closed state but prevents electro-magnetic radiation from escaping from the interior of the library; (c) openings 216A-216C that respectively form portions of the openings 206A-206C; (d) locator pin holes 218A-218C that cooperate with locator pins that are associated with the plastic portion 210 to facilitate the mating of the plastic portion 210 to the sheet metal portion 208; and (e) socket portions 220A-220D of ball-and-socket clips (aka Tinneman clips) that are used to attach/detach the plastic portion 210 to the sheet metal portion 208. The plastic portion 210 comprises: (a) a window 222 that, when the plastic portion 210 is properly mated with the sheet metal portion 208, is located adjacent to the second screen portion 214 of the sheet metal portion 208; (b) openings 224A-224C that cooperate with the openings 216A-216C to form the openings 206A-206C when the plastic portion 210 is properly mated with the sheet metal portion 208; (c) locator pins 226A-226C that cooperate with the locator pin holes 218A-218C to facilitate alignment of the plastic portion 210 with the sheet metal portion 208 when mating the plastic portion 210 to the sheet metal portion; (d) balls 228A-228D for engaging the sockets 220A-220D associated with the sheet metal portion 208 to facilitate attachment/detachment of the plastic portion 210 to/from the sheet metal portion 208. With reference to FIGS. 6A-6C, the entry/exit port 104 is of a type that moves a magazine frame or mount between an “open” position, as shown in FIG. 6A, and a “closed” position as shown in FIG. 1A. When the magazine frame is in the “open” position, a user can attach a magazine to the magazine frame. Further, if a magazine is attached to the magazine frame and the magazine frame is in the open position, a user can insert a data cartridge into the library by placing a data cartridge in one of the slots of the magazine (either before or after the magazine is attached to the magazine frame) and then causing the magazine frame to move to the “closed” position. After the magazine frame is in the “closed” position, the data cartridge is accessible to the transport assembly. Consequently, if desired, the transport assembly can be used to move the data cartridge to any space within the library that is accessible to the transport assembly and capable of storing the data cartridge. One advantage of employing a magazine is that the magazine can be populated with multiple data cartridges, thereby allowing multiple data cartridges to be loaded into the library at one time. If, on the other hand, a magazine is attached to the magazine frame and a user wants to remove a data cartridge from the library, the magazine frame is placed in the “closed” position. If the desired data cartridge is not already in the magazine, the transport assembly is used to move the desired data cartridge to the magazine. After the desired data cartridge is loaded into the magazine, the magazine frame is caused to move from the “closed” position to the “open” position so that the user can remove the desired data cartridge from the magazine. One advantage of employing a magazine is that multiple data cartridges can be removed from library at one time, either by removing the cartridges from the magazine or disengaging the magazine from the frame. With reference to FIGS. 6A-6C, the entry/exit port 104 is comprised of: (a) a magazine frame 240; (b) a guide structure 242 for supporting the magazine frame 240 and guiding the magazine frame between “open” and “closed” positions; (c) a drive mechanism 244 for applying a motive force to the magazine frame 240 to drive the magazine frame between the “open” and “closed” positions; and (d) a sensor system 246 for use in determining when the magazine frame 240 is in the “open” position and when the magazine frame is in the “closed” position. With continuing reference to FIGS. 6B-6C, the magazine frame 240 is comprised of: (a) a top guide channel 248; (b) a bottom bracket 250; (c) a front side bracket 252 that is attached to the top guide channel 248 and the bottom bracket 250; (d) a back side bracket 254 that is attached to the top guide channel 248 and the bottom bracket 250; (e) a bottom rail 256 that is operatively attached to the bottom bracket 250; (f) a rack 258 that is operatively attached to the bottom bracket 250; and (g) a stop 262, operatively attached to the bottom bracket 250, for preventing the drive mechanism 244 from driving the magazine frame 240 beyond the “open” and “closed” positions. The front side bracket 252, back side bracket 254, a portion of the top guide channel 248 and a portion of the bottom bracket 250 form a magazine receptacle 264 for receiving a magazine. Further, the front side bracket 252 and back side bracket 254 each respectively comprise a first flange engagement structure 268A and second flange engagement structure 268B that are each capable of receiving and engaging one of a pair of flanges associated with a magazine to secure the magazine within the receptacle 264. The first and second flange engagement structures 268A, 268B, if engaging the pair of flanges associated with a magazine, can also be disengaged from the flanges so that the magazine can be removed from the receptacle 264. The first and second flange engagement structures 268A, 268B are located such that the magazine can only be received in the magazine receptacle 264 when the magazine is in a particular orientation. Also associated with the front side bracket 252 is a cover mounting bracket 270 that support a entry/exit port cover 272. With continuing reference to FIGS. 6A-6C, the guide structure 242 is comprised of a top guide structure 274 that engages the top guide channel 248. The top guide structure 274 is comprised of a bracket 276 that is attached to the exterior skin 178B and two pairs of rollers 278A, 278B that each engage a flange of the top guide channel 248 to guide the magazine frame 240. The guide structure 242 is further comprised of a bottom guide structure 280 that engages the bottom rail 256. The bottom guide structure 280 is comprised of a bracket 282 that supports rail brackets 284A, 284B. The rail brackets 284A, 284B capture the rail 256 and allow the rail 256 to be linearly displaced so that the frame can be moved between the “open” and “closed” positions. The drive mechanism 244 is comprised of the rack 258, a stepper motor 288 that is attached to the mounting bracket 282, a pinion 290 that is attached to the spindle of the motor 286, and a cluster gear 292 that connects the rack 258 and the pinion 290. In operation, the stepper motor 288 produces a motive force that is used to translate the magazine frame 240 between the “closed” and “open” positions. More specifically, the stepper motor 288 produces a rotational motive force that is transferred to the rack 258 via the pinion 290 and the cluster gear 292. The interaction of the cluster gear 292 and the rack 258 translates the rotation motive force into a translational motive force that is used to move the magazine frame 240 between the “closed” and “open” positions. The stepper motor 288 is capable of being controlled so as to rotate the spindle in either a clockwise direction or a counter-clockwise direction. Rotation of the motor spindle in the clockwise direction causes the magazine frame 240 to move towards the “open” position. Conversely, rotation of the motor spindle in the counter-clockwise direction causes the frame to move towards the “closed” position. The sensor system 246 is comprised of a flag 294 that is attached to the bottom bracket 250 of the magazine frame 240, a first detector 296 for detecting when the magazine frame 240 is in the “open” position and that is attached to the mounting bracket 284B, a second detector 298 for detecting when the magazine frame 240 is in the “closed” position. The second detector 298 is supported by a bracket 300 that is attached to the side portion 184B of the bottom tray 186. In operation, the sensor system 246 detects that the magazine frame 240 is in the “open” position when the first detector 296 detects the flag 294. Similarly, the sensor system 246 detects that the magazine frame 240 is in the “closed” position when the second detector 298 detects the flag 294. The sensor system 246 is further comprised of a comb flag 302 and a third sensor 304 that are used to determine the position of the frame 240 when the frame 240 is located between the “open” and “closed” positions. With continuing reference to FIGS. 6A-6C, the stop 262 engages a portion of the bracket 300 to prevent the drive mechanism 244 from driving the magazine frame 240 beyond the “closed” position. The stop 262 engages the bracket 282 to prevent the drive mechanism 244 from driving the magazine frame 240 beyond the “open” position. The stop 262 is attached to the bottom bracket 250 by four screws 306. Notably, the magazine frame 240 can be disengaged from the guide structure by unscrewing the four screws 306 so that the stop 262 is no longer attached to the bottom bracket 250, thereby allowing the frame 240 to be displaced beyond the “open” position. With reference to FIGS. 7A-7F, an embodiment of a entry/exit port magazine 310 that is capable of holding a plurality of LTO tape cartridges and being engaged/disengaged to/from the magazine frame 240 of the entry/exit port 104 is described. The magazine 310 is comprised of a cartridge holding portion 312 and a dust cover 314. The cartridge holding portion 312 is comprised of a bottom wall 316 and a side wall 318 that extends from the bottom wall 316 to a side wall edge 320, which defines the opening through which an LTO cartridge is inserted/extracted into/from the magazine 310. The side wall 318 is comprised of first and second end walls 322A, 322B and first and second side walls 324A, 324B. Respectively associated with the first and second side walls 324A, 324B are first and second frame engagement structures 326A, 326B. The first frame engagement structure 326A is comprised of a first substantially rigid flange 328A that extends outward from the first side wall 324A and a first pair of ribs 330A, 332A. Similarly, the second frame engagement structure 326B is comprised of a substantially rigid flange 328B that extends outward from the second side wall 324B and a second pair of ribs 330B, 332B. The first substantially rigid flange 328A comprises a first engagement surface 334A that is located at a first distance from the edge 320. Similarly, the second substantially rigid flange 328B comprises a second engagement surface 334B that is also located at the first distance from the edge 320. The bottom edges of the first pair of ribs 330A, 332A and second pair of 330B, 332B are each located at a second distance from the edge 320 that is less than the first distance. The difference between the first and second distances is slightly greater than the thickness of the material in which the first and second flange engagement structures 268A, 268B have been established. To engage the magazine 310 to the frame 240 of the entry/exit port 104 (assuming the port is in the “open” position), the magazine is inserted into the receptacle 264 such that the substantially rigid flanges 328A, 328B are respectively pass through the wider openings located towards the top ends of the first and second flange engagement structures 268A, 268B. The first pair of ribs 330A, 332A and the second pair of ribs 330B, 332B respectively engage the back side bracket 254 and the front side bracket 252 to limit the extent to which the flanges 328A, 328B can pass through the larger portions of the first and second flange engagement structures 268A, 268B. At this point, the magazine 310 is displaced towards the bottom bracket 250 so that the first engagement surface 334A of the first flange 328A engages the posterior side of the back side bracket 254 and the second engagement surface 334B of the second flange 328B engages the posterior side of the front side bracket 252. At this point, the first engagement surface 334A is engaging the posterior side of the back side bracket 254 and the bottom edges of the first pair of ribs 330A, 332A are engaging the anterior surface of the back side bracket 254. Likewise, the second engagement surface 334B is engaging the posterior side of the front side bracket 252 and the second pair of ribs 330B, 332B are engage the anterior surface of the front side bracket 252. With the first and second engagement surface s 334A, 334B and the bottom edges of the first and second pairs of ribs 330A, 332A, 330B, 332B engaged to the frame 240 in this manner, the position of the magazine is substantially fixed in two orthogonal dimensions. An end rib 334 associated with the first end wall 322A engages the bottom bracket 250 to limit the extent to which the magazine 310 can be displaced towards the bottom bracket 250. To disengage the magazine 310 from the frame 240 (still assuming the port 104 is in the “open” condition), the attachment operation is reversed, i.e., the magazine 310 is displaced away from the bottom bracket 250 until the first and second flanges can be pulled through the wider openings located towards the top ends of the first and second flange engagement structures 268A, 268B to disengage the magazine 310 from the frame. The first and second substantially rigid flanges 328A, 328B are also located so as to establish an asymmetry that constrains the magazine 310 to be mounted to the frame 240 in a single, preferred orientation. To elaborate, the asymmetry is established by locating the first flange 328A such that the flange is a first distance from the first end wall 322A and locating the second flange 328B such that the flange is a second distance from the second end wall 322B that is not equal to the first distance. In the illustrated embodiment, the first flange 328A is located at a first distance from the first end wall 322A and a second distance from the second end wall 322B that is different than the first distance, and the second flange 328B is located the same second distance from the second end wall 322B. In addition, a cut-out 249 associated with the top guide channel 248 and the lack of a comparable cut-out associated with the bottom bracket 252 prevent the magazine 310 from being mounted to the frame 240 in an undesired orientation. Associated with the bottom wall 316 are a plurality of holes 336A-336D that are each engaged by a protrusion on the dust cover 314 of another magazine 310 to facilitate stacking of the magazines. There are numerous alternatives to the holes 336A-336D. Among the possible alternatives are: (a) one or more recesses that are each adapted to engage a protrusion on the dust cover of another magazine; and (b) one or more protrusions that are each adapted to engage a hole on the dust cover of another magazine. Different numbers of structures can be utilized. Moreover, a structure with a different shape than the holes 336A-336D is also feasible. With reference to FIGS. 7A, 7B, and 7D, the dust cover 314 comprises an exterior surface 338 and an interior surface 340. Associated with the exterior surface are protrusions 342A-342D that are each capable of mating with one of the plurality of holes 336A-336D associated with another magazine to facilitate stacking of the magazines. There are numerous alternative structures to the protrusions 342A-342D that can be used to facilitate stacking of magazines. For instances, holes or recesses that mate with protrusions located on the bottom wall of a magazine can be used in place of the protrusions 342A-342D. Different numbers of structures and/or structures with different shapes from those illustrated can also be utilized. Associated with the interior surface 340 of the cover 314 are a first pair of detents 344A, 344B and a second pair of detents 346A, 346B that are used to fasten the cover 314 to the cartridge holding portion 312. To elaborate, the first pair of detents 344A, 344B are adapted to engage a portion of a lip that is associated with the edge 320 and that is located adjacent to first flange 328A, and the second pair of detents 346A, 346B are adapted to engage a portion of the lip that is located adjacent to the second flange 328B. A pair of tabs 348A, 348B allow a user to disengage the cover 314 from the cartridge holding portion 312. To elaborate, the first tab 348A allows a user to flex the cover 314 (which is preferably made of plastic) adjacent to the first pair of detents 344A, 344B in a manner that disengages the first pair of detents 344A, 344B from the lip. The second tab 348B similarly allows a user to disengage the second pair of detents 346A, 346B from the lip. Respectively associated with the first and second end walls 322A, 322B are first and second bar code areas 350A, 350B that are each capable of accommodating a bar code. In many cases, the bar code is imprinted on a label that is placed in the bar code area. In some embodiments, a single bar code area that is associated with one of the first and second end walls 322A, 322B or one of the first and second side walls 324A, 324B is adequate. In other embodiments, two or more bar codes areas, each associated with one of the first and second end walls 322A, 322B and the first and second side walls 324A, 324B is needed or desirable. Extending from the second end wall 322B is a third bar code area 350C, which is shown with a bar code label attached. The third bar code area is located so that when the magazine 310 is within the library, the magazine can be identified. To elaborate, when the magazine 310 is attached to the magazine frame 240, any bar codes associated with the first and second bar code areas 350A, 350B or associated with any other locations on the side wall 318 are likely to be difficult for a bar code reader associated with the transport system 112 to read. In contrast, a bar code associated with the third bar code area 350C is readily visible to such a bar code reader. Generally, any bar code associated with the third bar code area 350C is identical to the bar code associated with the first and second bar code areas 350A, 350B. However, it is not required that a bar code associated with an individual magazine be identical to any other bar codes associated with the magazine. With reference to FIGS. 7E and 7F, the bottom wall 316, the first and second end walls 322A, 322B, the first and second side walls 324A, 324B define an interior space that is capable of accommodating a plurality of the LTO tape cartridges. In the illustrated embodiment, three LTO cartridges are shown located within the interior space of the magazine 310. A plurality of partition structures 352 divide the interior space into a plurality of data cartridge storage spaces 354, each being capable of accommodating a single LTO tape cartridge. Each partition 352 is comprised of a pair of panels 356A, 356B and a pair of spacer ribs 358A, 358B. The spacer ribs 358A, 358B serve to space cartridges that are stored in adjacent storage spaces a sufficient distance from one another so that the picker associated with the transport assembly can grasp one of the cartridges without interference from any adjacent cartridges. Associated with each of the storage space 354 is a pair of centering fins 360A, 360B that serve to center a data cartridge within the storage space. Also associated with each storage space 354 is an orientation structure 362 that prevents insertion of an LTO tape cartridge into space if the cartridge does not have the proper orientation. To elaborate, the orientation structure 362 is designed to accommodate or complement the orientation feature 138 of an LTO tape cartridge that is being inserted into the space and has the desired orientation. If, however, an LTO tape cartridge is being inserted into the space and does not have the desired orientation, the orientation structure 362 is not positioned to accommodate the orientation feature 138 of the LTO tape cartridge and, as such, interferes with the insertion of the LTO tape cartridge into the space. Further, all of the orientation structures 362 in the magazine 310 are substantially identical to one another and in substantially the same location in each storage space. Consequently, the orientation structures cumulatively operate to ensure that all of the cartridges that can be held by the magazine have the same orientation within the magazine. This characteristic of the magazine, in combination with the features of the magazine that require the magazine to be in a specific orientation for attachment to the magazine frame 240 of the entry/exit port 104, ensure that all of the data cartridge that are placed in the library via the entry/exit port 104 have the same orientation relative to the picker, which facilitates the design of the picker. Additionally, a retaining structure 364 is associated with each of the storage spaces 354 to prevent unintentional dislodgement of an LTO cartridge located in the space. Generally, the retaining structure comprises a cantilever member with one end fixed to the cartridge holding portion 312 and a free or movable end that supports a detent for engaging the notch 142B of an LTO cartridge. In operation, the spring force provided by the cantilever member urges the detent into engagement with the notch 142B during insertion of the LTO cartridge into the cartridge holding portion 312 and allows the detent to disengage from the notch during extraction of the cartridge by a picker or user. Each of the storage spaces 354 also comprises portions of stand-offs 366A, 366B that ensure that the cartridge end 136A of the LTO cartridge is substantially the same distance from the bottom wall of the 316 of the magazine 310 as the cartridge end 156A of a DLT tape cartridge is from the bottom wall of a magazine designed to accommodate DLT tape cartridges. In libraries that are capable of operating on cartridges with different dimensions, such as library 100, the use of stand-offs to ensure this consistency of cartridge location simplifies the picker design. Associated with the side wall 324A are two orientation surfaces 368A, 368B that can each be used by a picker to locate the data cartridge storage spaces 354. The cover 314 is designed to accommodate the orientation surfaces 368A, 368B. Associated with the side wall 324B are blockers 369A, 369B that serve to prevent the magazine frame 240 of the entry/exit port 104 from reaching the closed position, as shown in FIG. 1A, if the magazine 310 is not fully engaged to the frame 240. Associated with one of the partitions 352 is a strut 370 that connects the pair of panels 356A, 356B. The strut 370 prevents the first and second side walls 324A, 324B from bowing towards or away from one another. A picker space 372 associated with the storage space 254 immediately adjacent to the first end wall 322 provides space that is utilized by a picker in inserting a data cartridge into the space 254 and retracting a data cartridge from the space 254. With reference to FIGS. 2 and 8A-8E, the magazine structure 106 comprises first and second banks of magazines 380A, 380B. The first bank of magazines 380A is described with the understanding that the second bank of magazines 380B (other than accommodating the entry/exit port 104) is substantially identical. The first bank of magazines 380A is comprised of four, multi-piece magazines 382A-382D. With reference to FIG. 8A, each of the multi-piece magazines 328A-382D is comprised of a back side 384, a first side 386A, and a second side 386B that cumulatively define an interior space for accommodating a plurality of data cartridges and an opening through which data cartridges can be inserted/extracted into/from the interior space. Each of the multi-piece magazines 382A-382D also comprises a partitioning structure 388 that divides the interior space into a plurality of storage spaces that are each capable of accommodating an LTO tape data cartridge. With reference to FIGS. 8A-8E, each of the multi-piece magazines 382A-382D is comprised of a C-channel 390 and at least one magazine clip 392. The C-channel 390 forms substantially the entire back side 384 of the magazine and portions of the first and second sides 386A, 386B of the magazine. The C-channel 390 comprises first and second C-channel sides 394A, 394B and a C-channel mid-section 396 that extends between and connects the first and second C-channel sides 394A, 394B. The C-channel mid-section 396 forms substantially the entire back side 384 of the magazine. In addition, the C-channel mid-section 396 comprises a plurality of stand-offs 398, with each stand-off positioned to engage at least one LTO tape cartridge located in one of the storage spaces provided by the magazine such that the cartridge end 136A of the LTO cartridge is substantially the same distance from the back side 384 as the cartridge end 156A of a DLT tape cartridge is from the back side 384 of a magazine designed to accommodate DLT tape cartridges. In libraries that are capable of operating on cartridges with different dimensions, such as library 100, the use of stand-offs to ensure this consistency of cartridge location simplifies the picker design. The C-channel mid-section 396 further comprises a plurality of rivet holes 400 that allow the C-channel 390 to be attached to the top tray 182, bottom tray 186, and exterior skins 178A, 178B by rivets. The C-channel 390, in connecting the top tray 182 and the bottom 186 to one another, also provides structural support that is not provided by the exterior skins 178A, 178B. Consequently, each of the C-channels forms a structural portion the frame 102. Respectively associated with the first and second C-channel sides 394A, 394B are first latch elements 402A, 402B that each form a latch with a second latch element associated with the magazine clip 392 to join the magazine clip and the C-channel 390. In the illustrated embodiment, the first latch elements 402A-402B are holes. However, other types of latch elements are feasible. A plurality of slits 404 are also associated with each of the first and second C-channel sides 394A, 394B. The slits 404 cooperate with slot defining structures that are associated with the magazine clip 392 to further fix the magazine clip 292 to the C-channel 390 in the manner that slotted cards are interconnected to build a house of cards. The C-channel 390 is preferably made of a metal (aluminum, sheet steel etc.). Further, the C-channel of each of the magazines in the first bank of magazines 380A forms a portion of the frame 102 of the library 101. This is also the case with respect to the second bank of magazines 380B with the possible exception of the magazine situation above the entry/exit port 104. The magazine clip 392 is comprised of a side wall 406 that extends from a bottom edge 408 to a top edge 410 that defines an opening through which an LTO cartridge is inserted/extracted into/from the magazine when the magazine clip 392 is joined to the C-channel 390. The side wall 406 is comprised of first and second end walls 412A, 412B and first and second side walls 414A, 414B. Associated with the first and second side walls 414A, 414B are second latch elements 416A-416B that respectively cooperate with first latch elements 402A-402B of the C-channel 390 to connect the magazine clip 392 and the C-channel 390. In the illustrated embodiment, the second latch elements 416A-416B are each substantially rigid flanges. In joining the magazine clip 392 to the C-channel 390, the magazine clip 392 are brought together such that the second latch elements 416A, 416B cause the first and second C-channel sides 394A, 394B to flex or spread apart. Once, however, the second latch elements 416A, 416B reach the first latch elements 402A, 402B, the first and second C-channel side 394A, 394B come together to latch the magazine clip 392 and the C-channel 390. Also associated with the first and second side walls 414A, 414B are slot defining structures 418 that are each adapted to engage one of the slits 404 associated with the first and second C-channel sides 394A, 394B. The slot defining structures 418 and slits 404 operate to prevent the magazine clip 392 from being displaced towards the top tray 182 or the bottom tray 186. The magazine clip 392 further comprises a plurality of partitions 420 that define a plurality of LTO tape cartridge storage spaces 422. Each of the partitions 420 is comprised of a panel 424, pair of spacer ribs 426A, 426B that are each substantially identical to the comparable element associated with the entry/exit port magazine 310 and perform substantially the same function as the comparable element of the entry/exit port magazine 310. As such, these elements will not be described further. Associated with each of the storage spaces 422 are centering fins 428A, 428B and a retaining structure 430, which are each substantially identical to the comparable element associated with the entry/exit port magazine 310 and perform substantially the same function as the comparable element in the magazine 310. Consequently, these features will not be described further. Notably, the magazine clip 392 does not include any kind of orientation feature for ensuring that cartridges held by the magazine have a predetermined orientation. The magazine clip 392 lacks an orientation feature because it is assumed that substantially all of the data cartridges that will be held by any one of the magazine associated with the first and second banks of magazines 380A, 380B will enter the library via the entry/exit port 104 and, as such, will have the desired predetermined orientation due to the operation of the entry/exit port 104 and the entry/exit port magazine 310. The magazine clip 392 also does not have any kind of back wall or stand-off feature like the entry/exit port magazine 310, nor does it need any of these features because these features are provided by the C-channel 390. Consequently, absent the operation of the retaining structure 430 associated with each data cartridge storage space of the magazine clip 392 and the attachment of the clip 392 to the C-channel 390, a data cartridge can be passed all the way through the magazine clip 392. For example, a data cartridge could be inserted into the magazine clip 392 through the opening defined by the top edge 410 and, absent the operation of the retaining structure, be extracted through an opening defined, at least in part by the bottom edge 408. The magazine clip 392 is made of one of the same class of materials as is used to make the cartridge housing of a data cartridge. Consequently, at present, the magazine clip 392 is made of plastic. The use of plastic to make the magazine clip 392 results in less wear and tear on the cartridge housings over numerous insertions and extractions relative to a clip made of, for example, metal. For cartridges with dimensions that would place the cartridge end at a different distance from the back side 384 of a magazine designed to accommodate LTO cartridges, such as magazine 382A, there are at least two possible ways to design the magazine so that the cartridge will be at the same distance from the back side and thereby facilitate the picker design. First, a shim can be attached to the stand-offs 398. Second, the magazine clip can be designed to hold the cartridge at the desired distance. It should be appreciated that a multi-piece magazine can be realized in which one piece forms at least a portion of the back of the magazine that does not have a C-shape or U-shape. For example, a multi-piece magazine can be realized in which a substantially flat piece of material forms at least a portion of the back of the magazine. Additionally, a multi-piece magazine can be realized in which a piece that forms at least a portion of the back of the magazine and a piece that forms at least portions of the side are attached to one another in a manner that does not involve overlapping side portions provided by each of the pieces. For example, the pieces can be joined to one another with a connector that forms a butt joint between the pieces. With reference to FIGS. 9A-9F, the drive bay 108 is comprised of a frame 442 that defines a drive bay space which is capable of accommodating a number of LTO drives that are each contained within a drive sled that facilitates hot-swapping of drives to and from the library 100. The frame 442 defines a first opening 444 (see FIG. 2) that exposes any drives appropriately located in the drive bay 108 so to the transport system 112 can load and unload tape cartridges from the drive. The frame 442 also defines a second opening 446 that allows a user to insert and remove drives from the drive bay space. With reference to FIG. 9B, which is a cross-sectional view of the drive bay 108, the drive bay 108 is further comprised of five fixed-partitions 448A-448E that divide the drive bay space into six, full-height drive spaces 450A-450F, each capable of accommodating a full-height LTO drive located in a drive sled. The portion of the frame 442 adjacent to each of the full-height drive spaces 450A-450F defines a pair of slots 452A, 452B that are capable of engaging an insertable/removable partition 454. If the partition 454 engages one of the pair of slots 452A, 452B, the full-height drive space with which the pair of slots is associated is divided into two, half-height drive spaces 456A, 456B, each capable of accommodating a half-height drive located within a drive sled. Consequently, the drive bay 108 can be configured to provide twelve half-height drive spaces. However, because of the operation of the transport assembly 112, the upper-most and lower-most half-height drive spaces cannot be utilized. As a consequence, only the middle ten of the twelve possible half-height drive spaces can be utilized. In libraries that employ different transport assemblies and/or have different dimensions, this constraint on the number of half-height drives may not be present and, as such, all of the possible half-height drive spaces will be capable of being utilized. Associated with each of the full-height drive spaces 450A-450F are first and second plugs 458A, 458B that are used to provide power and intra-library control via a controller area network (CAN) to a full-height drive located in the space. If a full-height drive space is divided into two, half-height drive spaces, the first plug 458A is used to provide power to any half-height drive located in the half-height drive space 456A (i.e., the upper, half-height drive space) and the second plug 458B is used to provide power to any half-height drive located in the half-height drive space 456B (i.e., the lower, half-height drive space). As should be appreciated, the drive bay 108 is capable of accommodating only full-height drives, only half-height drives, combinations of full-height and half-height drives, and less than a full complement of drives. For example, FIG. 9C shows the drive bay 108 configured such that the full-height drive space 450B has been partitioned into two, half-height drive spaces with one space containing a half-height drive and the other space containing a half-height drive block-off plate; a full-height drive in full-height drive space 450F; and full-height drive block-off plates 460 in each of full-height drives spaces 450A, 450C, 450D and 450E. FIGS. 9D-9F illustrate a drive sled 470 for housing a full-height LTO tape drive 472. The LTO tape drive 472 is shown with an LTO tape cartridge 474 inserted in the receptacle of the drive. The drive sled 470 generally facilitates the insertion/removal of a drive into/from the drive bay 108 via the second open side 446 of the drive bay 108. More specifically, the drive sled 470 facilitates insertion of a drive by allowing a power connection to be established between the drive and one of the plugs 458A, 458B by inserting the drive and the sled into one of the full-height drive spaces 450A-450F. The drive sled 470 facilitates removal of a drive by allowing a power connection between a drive and one of the plugs 458A, 458B to be terminated by extracting the sled from the full-height drive space 450A-450F in which the drive and sled are resident. The sled 470 comprises a housing 476 with a front side 478A, back side 478B, first lateral side 478C, second lateral side 478D, top side 478E and bottom side 478F. Associated with the front side 478A are first and second plug receptacles 480A, 480B that are adapted to engage the plugs 458A, 458B associated with a full-height drive space within the drive bay 108. Associated with the back side 478B of the housing are a pair of SCSI connectors 484A, 484B that are respectively used to establish a “daisy chain” connection to a SCSI cable over which SCSI commands and data are transmitted to/from drives resident in the drive bay 108. Also associated with the back side 478B are: (a) a latch 486 that is used to retain the sled with a drive bay; (b) a handle 488 that facilitates the insertion and extraction of the sled 470 from the drive bay 108; (c) a grill 490 for moving air from the interior of the sled 470 to the exterior environment and thereby contribute to the cooling of any drive resident in the sled; and (d) an LED 491 that is used to provide a user with an indication of the operational status of any drive resident in the sled. Associated with the first lateral side 478C of the sled 470 is a spring latch 492 that is activated by the latch 486 and cooperates with the frame 442 of the drive bay 108 to retain the sled within one of the drive storage spaces. The first lateral side 478C also comprises a pair of mounting holes 494A, 494B that each receive a screw that, in turn, engages a threaded hole associated with the housing of a drive to fix the drive within the sled. Similarly, the second lateral side 478D comprises mounting holes 496A, 496B that each receive a screw that, in turn, engages a threaded hole associated with the housing of a drive to fix the drive within the sled. The top side 478E can be detached from the remainder of the housing 476 so that a drive can be inserted/extracted into/from the interior of the sled 470. The top side 478E is detached by removing a screw 498 and sliding the top side 478E (which is captured by overlying flanges 500A-500D and underlying flanges 502A-502F extending from the first and second lateral sides) rearward. With reference to FIG. 9F, the sled 470 comprises a fan 504 that operates to move air from the interior of the sled to the exterior environment via the grill 490. The sled further comprises a power distribution device 506 that distributes power received via one of the first and second receptacles 480A, 480B to the fan 504 and to any drive resident in the sled via a drive power connector 508. The power connector 508 is used to establish an electrical connection with the drive via a power cable that extends between the connector 508 and a power connection interface associated with the drive. Similarly, the interior sides of the SCSI connectors 484A, 484B are used to establish electrical connection with the SCSI interface of the drive via a SCSI cable. A half-height sled has substantially the same structure as the full-height sled 470. However, the half-height sled has only one plug receptacle for receiving power from one of the plugs 458A, 458B associated with a half-height drive space. With reference to FIGS. 10A-10B, the power supply/control module bay 114 is comprised of a frame 520 that defines an interior space that accommodates a library control module and a maximum of two power supplies. Generally, the frame 520 is comprised of a portion of the frame 442 of the drive bay 108, a portion of the top tray 182, a section of the side portion 180B, a section of the side portion 184B, a portion of the bottom tray 186, a divider 522, and exterior wall 524. The exterior wall 524 defines a library control module opening 526 for insertion/extraction of a library control module into/from the interior space; a power supply opening 528 for the insertion/extraction of power supplies into/from the interior space; and plug receptacle opening 530 for accommodating the plug receptacles that receive the AC power plugs that are used to provide the power used by any power supplies in the interior space. The bay 114 further comprises a library control module cage 532 for receiving a library control module that is used to distribute power to other elements within the library 100 and control the operation of the library 100. Also comprising the bay 114 is a power supply cage 534 that is capable of accommodating two power supplies. The library 100 only requires one power supply to operate. Nonetheless, the bay 114 is able to accommodate two power supplies so that there is a back-up power supply available and on-line should one of the two, power supplies fail, thereby enhancing the reliability of the library 100. FIG. 10B illustrate the power supply/library control module bay 114 fully populated, i.e. with a library control module 536 situated in the library control module cage 532 and first and second power supplies 538A, 538B located in the power supply cage 534. In addition, plug receptacles 540A, 540B are located in the plug receptacle opening 530. With reference to FIGS. 11A-11C, the universal bay 120 is generally for accommodating electronic or processing circuitry that can enhance or supplement the operation of the library 100 but is not electronic or processing circuitry that is necessary to the operation of the library, such necessary circuitry being located in the power supply/library control module bay 114 or elsewhere. It should also be noted that the universal bay 120 is located in a space that is separate from the spaces dedicated to the storage of data cartridges (including the entry/exit port 104); drives; the transport of data cartridges between the space for storing data cartridges the drives, power supply, and control systems necessary to the operation of the library 100. Moreover, space within the universal bay 120 is not accessible to the transport system 112. The universal bay 120 is comprised of a frame 550 that defines an interior space that accommodates enhancing or supplementing circuitry. Generally, the frame 550 is comprised of a portion of the frame 442 of the drive bay 108, a portion of the top tray 182, a section of the side portion 180A, a section of the side portion 184A, a portion of the bottom tray 186, and a divider 552. The frame also comprises an exterior wall 554 defines one or more openings that are adapted to receive the desired electronics. Since the desired electronics may be in a number of different forms the number of holes, the location of any holes, and the dimensions of any holes associated with the exterior wall 554 vary depending on the desired electronics. In the illustrated embodiment, the exterior 554 defines the openings needed for a quad-interface process (QIP) and a card cage that can be used to accommodate the cards needed to realize a PC or other device within the library 100. A QIP is a device that is capable of processing, relative to the drives within the library 100, SCSI data and command signals associated with four SCSI busses. Normally, the QIP operates with respect to four, full-height drives but is capable of operating with eight, half-height drives. Further comprising the universal bay 120 is a partition 556 that divides the interior space of the universal bay 120 into first and second spaces 558A, 558B. The partition 556 is removable. Consequently, should a user want to use more space than either the first space 558A or the second space 558B can provide, a greater amount of space is available. It should also be appreciated that partition structures are feasible that divide the interior space into a greater number of subsidiary spaces and into spaces with different dimension than those shown. Associated with the first space 558A is a first circuit board 560A that is operatively attached to the divider 552 and adapted to engage the interface of whatever type of circuitry is located in the first space 558A. Similarly, a second circuit board 560B is associated with the second space 558B. The second circuit board 560B is operatively attached to the divider 552 and adapted to engage the interface of whatever type of circuitry is located in the second space 558B. If the partition 556 is removed or never installed to realize a space that is bigger than that provided by either of the first and second space 558A, 558B, one or more circuit boards are attached to the divider 552 and adapted to engage the interface of whatever circuitry the user chooses to locate in the space. When the interior space of the universal bay 120 is divided into the first and second spaces 558A, 558B, there are presently the options of: (a) placing a QIP in one or both of the spaces; (b) placing a 3 U high CPCI card cage in one or both of the spaces; and (c) placing a 6U high card cage in the second space 558B, which is taller than the first space 558A. Presently, when the interior space of the universal bay 120 is undivided, the space is capable of supporting a two high, 6U card cage. For example and with reference to FIG. 11B, the universal bay 120 comprises a 3U card cage 562 located in the first space 558A and a QIP cage 564 located in the second space 558B. FIG. 11C illustrates the 3U card cage 562 populated with CPCI cards 566, and the QIP cage 564 housing a QIP 568. As should be appreciated, the use of the interior space within the universal bay 120 is not limited to the options described above. It should be appreciated that the configuration and any reconfiguration of the drive bay 108 with drives and/or configuration or reconfiguration of the universal bay 120 can be accomplished entirely from the rear side 170B of the library 100, thereby avoiding any need to remove the library 100 from an equipment rack. With reference to FIGS. 12A-12E, the transport system 112 is comprised of: (a) a picker 580 that is capable of grasping a data cartridge that is located in a storage space associated with the entry/exit port 104, magazine structure 106, any one of the drives located in the drive bay 108 and displacing a grasped data cartridge towards or away from a storage space; and (b) an elevator 582 that moves the picker 580 within the library 100 so that the picker 580 can perform the noted grasping and displacing operations. Due to the layout of the entry/exit port 104, the magazine structure 106 and the drive bay 108 and the need for the elevator to move the picker between each space associated with the entry/exit port 104, magazine structure 106 and the drive bay 108, the elevator 582 is capable of vertical and horizontal displacement of the picker 580, as well as rotation of the picker 580 about a vertical axis. The elevator 582 comprises a picker carriage 584 that supports the picker 580. The carriage 584 is comprised of a vertical member 586, a top bracket 588 that is connected to one end of the vertical member 586, and a bottom bracket 590 that is connected to the other end of the vertical member 586. Associated with the carriage 584 is a vertical displacement system 592 for vertically displacing to the picker 580 to a desired location between the top bracket 588 and the bottom bracket 590. The vertical displacement system 592 is comprised of: (a) a vertical linear rail 594 that is adapted to engage linear rail mounts associated with the picker 580 to guide the picker 580; (b) a vertical drive system 596 for providing the motive force to move the picker 580 to a desired location along the linear rail 594; and (c) a vertical position sensor system 598 for determining the location of the picker 580 along the linear rail 594. The vertical drive system 596 is comprised of: (a) a lead screw 600 with first and second ends that respectively journaled to the top bracket 588 and the bottom bracket 590; (b) a lead screw pulley 602 that is attached to the lead screw 600; (c) a stepper motor 604; (d) a spindle pulley 606 that is attached to the spindle of the stepper motor 604; and (e) a timing belt 608 that connects the lead screw pulley 602 and the spindle pulley 606. The vertical position sensor system 598 is comprised of: (a) a home sensor 610 that detects when the picker 580 is at a “home” position, which in this embodiment is adjacent to the bottom bracket 590; and (b) an encoder bar 612 that extends between the top bracket 588 and bottom bracket 590 and is used to determine the location of the picker 580 relative to the “home” position. Also associated with the vertical position sensor system 598 is a sensor that cooperates with the encoder bar 612 to provide information on the vertical position of the picker 580 relative to the “home” position. Operation of the vertical displacement system 592 comprises using the stepper motor 604 to drive the lead screw 600 in either a clockwise direction to cause the picker 580 to be displaced along the linear rail 594 and towards the top bracket 588 or a counter-clockwise direction to cause the picker 580 to be displaced along the linear rail 594 and towards the bottom bracket 590. The vertical sensor system 592 is used to control the stepper motor 604 so that the stepper motor 604 is operated to position the picker 580 at the desired vertical location. To rotate the picker 580, the transport system further comprises a rotational displacement system 620 that is used to rotate the picker carriage 584 and, as a consequence, the picker 580. The rotational displacement system 620 comprises: (a) a top plate 622 and bottom plate 624 that are respectively journaled to the top bracket 588 and the bottom bracket 590 of the carriage 584 to guide the rotational movement of the carriage 584; (b) a rotational drive system 626 for providing the motive force to rotate the carriage 586 and the picker 580 to a desired rotational position relative to the top plate 622 and the bottom plate 624; and (c) a rotational position sensor system 628 for determining the rotational position of the carriage 584 and the picker 580. The rotational displacement system 620 further comprises a limiting system 630 for limiting the range of rotation of the carriage 584 and the picker 580. The rotational drive system 626 comprises: (a) a stepper motor 632 that provides the motive force for rotating the carriage 584 and the picker 580 relative to the top plate 622 and bottom plate 624; (b) a sector gear 634 that is operatively attached to the bottom plate 624; (c) a pinion 636 that is operatively attached to the spindle of the stepper motor 632; and (d) a cluster gear 638 that is operatively attached to the bottom bracket 590 of the carriage 584 and that operates to transfer a rotational force from the pinion 636 to the sector gear 634. The rotational position sensor system 628 comprises: (a) a flag 640 that is operatively attached to the bottom bracket 590 of the carriage 584; and (b) a detector 642 that operates to detect the flag 640 and thereby provide an indication of when the carriage 584 and picker 580 are at a “home” rotational position. Once the “home” position is detected using the flag 640 and the detector 642, the signals provided to the stepper motor to cause rotation of the carriage 584 and the picker 580 are also used to calculate the rotational position of the carriage 584 and the picker 580 relative to the “home” position. The limiting system 630 operates to limit the rotation of the carriage 584 and the picker 580 to the approximately 180 degree range that is needed to move data cartridges between any of the storage and drive spaces within the library 100 that are capable of accommodating a data cartridge. The limiting system 630 comprises: (a) first and second hard stops 644A, 644B that are operatively connected to the bottom plate 624; and (b) member 646 that is operatively connected to the bottom bracket 590 of the carriage 584 and positioned to engage the first and second hard stops 644A, 644B to prevent rotation of the carriage 584 beyond the desired range. Operation of the rotational displacement system 620 comprises using the stepper motor 632, pinion 636, cluster gear 638, and sector gear 634 to rotate the carriage 584 in a clockwise or counter-clockwise direction. The rotational position sensor system 628 is used to control the stepper motor 632 so that the stepper motor 632 positions the picker 580 at the desired rotational position. The limiting system 630 operates to limit the range of rotational positions at which the rotational drive system 626 can position the carriage 584 and picker 580. The transport system further comprises a horizontal displacement system 650 for horizontally translating the picker 580. The horizontal displacement system 650 comprises: (a) a top guide system 652 for horizontally guiding the top bracket 588 of the carriage 584; (b) a bottom guide system 654 for horizontally guiding the bottom bracket 590 of the carriage 584; (c) a horizontal drive system 656 for providing the motive force to drive the carriage 586 and the picker 580 to a desired horizontal position; and (d) a horizontal position sensor system 658 for determining the horizontal position of the carriage 584 and the picker 580. The top guide system 652 is comprised of: (a) a pair of rails 660A, 660B that are attached to the top tray 182; and (b) a roller system 662 that is comprised of a plate 664 that is fixed to the top plate 622 of the rotational displacement system 620 and a pair of rollers 666A, 666B that each engage the rails 660A, 660B. Each of the rollers 666A, 666B is pivotally attached to the plate 664. The bottom guide system 654 is comprised of: (a) a horizontal linear rail 668 that is operatively attached to robotics module tray 670; and (b) a pair of linear rail mounts (not shown) that are operatively attached to the bottom plate 624 of the rotational displacement system and engage the horizontal linear rail 668. The horizontal drive system 656 is comprised of: (a) a stepper motor 672 that is attached to the robotic module tray 670 and provides the motive force for horizontally displacing the carriage 584 and the picker 580 that is attached to the carriage; (b) a bottom drive system 674 for applying a motive force to the bottom plate 624; (c) a top drive system 676 for applying a motive force to the top plate 622; and (d) a shaft 678 for transmitting a motive force from the bottom drive system 674 to the top drive system 676. The bottom drive system 674 is comprised of: (a) drive pulley 680 that is attached to the spindle of the stepper motor 672; (b) a cluster pulley 682 that is operatively attached to the tray 670; (c) a first shaft pulley 684 that is also operatively attached to the tray 670; (d) a first timing belt 686 that extends between the drive pulley 680 and the cluster pulley 682; (e) a second timing belt 688 that extends between the cluster pulley 682 and the first shaft pulley 684; and (f) a connecting bracket 690 that connects the second timing belt 688 to the bottom plate 624. The connecting bracket 690 also incorporates a device for tensioning the second timing belt 688. Alternatively, tensioning of the second timing belt 688 can be accomplished by providing a structure for adjusting the position of at least one of the cluster pulley 682 and the first shaft pulley 684. The top drive system 676 is comprised of: (a) pulley 692 that is attached to the top tray 182 via a bracket 694; (b) a second shaft pulley 696 that is attached to the top tray 182 via a bracket 698; (c) a third timing belt 700 that extends between the pulley 692 and the second shaft pulley 696; and (d) a connecting bracket 701 that connects the third timing belt 700 to the top plate 622. The connecting bracket 701 also incorporates a device for tensioning the third timing belt 700. A screw connection 701A allows the plate 664 to be quickly disconnected from the top plate 622. The shaft 678 comprises: (a) a first shaft piece 702 that is operatively connected to the cluster pulley 682; (b) a second shaft piece 704 that is operatively connected to the second shaft pulley 692; and (c) a connector 706 that is used to connect the first shaft piece 702 and the second shaft piece 704. The connector 706 comprises a first spline that is associated with the first shaft piece 702, a second spline that is associated with the second shaft piece 704, and a spline sleeve 708 that is attached to the second shaft piece 704. The spline sleeve 708, as a result of its engagement with the second spline, is constrained such that it is not able to rotate about the second shaft piece 704 but is capable of being linearly displaced to engage and disengage the first shaft piece 702 and the second shaft piece 704. To elaborate, by sliding the spline sleeve 708 towards the first shaft 702, the spline sleeve 708 engages the spline of the first shaft piece 702 to connect the first shaft piece 702 and the second shaft piece 704. Conversely, by sliding the spline sleeve 708 away from the first shaft 702, the spline sleeve 708 disengages from the spline of the first shaft piece 702 to disengage the first shaft piece 702 and the second shaft piece 704. A collared spring structure 710 is used to bias the spline sleeve 708 towards engagement with the first shaft piece 702. Other biasing devices are feasible. Other coupling devices are also feasible. For example, the first shaft piece 702 and the second shaft piece 704 can be connected to one another and disconnected from one another using a clamping shaft coupler that utilizes a screw to adjust the diameter of a collar to engage or disengage the shaft pieces. The horizontal position sensor system 658 comprises: (a) a home sensor 712 for sensing when the carriage 584 and the picker 580 are at a horizontal “home” position from which other horizontal positions can be determined; (b) a coarse horizontal position sensor 714 for determining the coarse position of the carriage 584 and the picker 580; and (c) a fine horizontal position sensor 716. The coarse horizontal position sensor 714 comprises a coarse flag 718 that is operatively attached to the tray 670 and a coarse detector 720 that is operatively attached to the bottom plate 624 and that cooperates with the coarse flag 718 to determine the half of the range of possible horizontal positions in which the carriage 584 and the picker 580 are located. The fine horizontal position sensor 716 comprises a fine, crenelated flag 722 and a fine detector 724 that is operatively attached to the bottom plate 624 and that cooperates with the crenelated fine flag 722 to provide a higher resolution determination of the location of the carriage 584 and the picker 580 than provided by the coarse detector 720. Operation of the horizontal displacement system 650 comprises using the stepper motor 672 to provide a motive force that is used to horizontally displace the carriage 584 and the picker 580 towards or away from the drive bay 08 as constrained by the top guide system 652 and the bottom guide system 654. The motive force produced by the stepper motor 672 is transmitted to the carriage 584 via the bottom drive system 674, top drive system 676, and shaft 678. The horizontal position sensor system 58 is used to determine the current position of the carriage 584 and the picker 580 relative to the “home” position. With reference to FIGS. 14A-14F, the picker 580 is comprised of: (a) a base plate 800 that supports other elements of the picker; (b) a grasper assembly 802 that is capable of being placed in a “closed” state in which a data cartridge can be grasped and an “open” state in which a data cartridge can not be grasped; (c) a pusher plate assembly 804 that supports the grasper assembly 802 and is used in moving the grasper assembly towards and away from a location in which a data cartridge is located or may be located; and (d) a crank assembly 806 that provides the motive forces needed to place the grasper assembly 802 in the “open” or “closed” states and to move the pusher plate assembly 804. In addition to supporting other elements of the picker, the base plate 800 also supports elements of the vertical displacement system 592 that are used to position the picker 580 at a desired vertical location. Specifically, the base plate 800 supports: (a) a pair of mounts 810A, 810B that connect the base plate 800 to the vertical linear rail 594; (b) a lead screw nut 812 that receives the lead screw 600; and (c) a vertical encoder sensor 814 that cooperates with the encoder bar 512 to provide information that is used to determine the vertical position of the picker 580. Rotation of the lead screw 600 provides a motive force that is applied to the base plate 800 via the lead screw nut 812 to move the base plate to a desired vertical location along the vertical linear rail 594. The grasper assembly 802 is comprised of: (a) a static member 820 that has a first surface 822 for engaging one side of a data cartridge; and (b) a moving member system 824 that has a second surface 826 for engaging the opposite side of a data cartridge. The moving member system 824 is also capable of being moved between a “closed” position in which the second surface 826 and the first surface 822 are capable of grasping a data cartridge and an “open” position in which the second surface 826 and the first surface 822 are not capable of grasping a data cartridge. The grasper assembly 802 is further comprised of a bias system 828 that serves to bias the moving member system 824 such that the second surface 826 is forced towards the “closed” position. Further comprising the grasper assembly 802 is grasper cam follower 830 that interacts with a grasper cam driver associated with the crank assembly 106 to force the moving member 824 towards the “open” position. It should be appreciated that grasping assemblies in which two moving members are used to grasp and release a data cartridge are also feasible. Further, grasping assemblies in which there is a bias system that biases one or more members that are used to grasp a data cartridge towards an “open” position are feasible. Similarly, grasper assemblies that employ a grasper cam follower that forces one or more member that are used to grasp a data cartridge towards a “closed” position are feasible. The moving member system 824 is comprised of: (a) an upper jaw 836; (b) a jaw grip 838 that is attached to the upper jaw 836 and provides the second surface 826; (c) a mount 840; (d) a u-shaped linkage 842 that extends between the mount 840 and the upper jaw 836; and (e) a link 844 that also extends between the mount 840 and the upper jaw 836. The jaw grip 838 is typically made of rubber or some other material that provides a good grip. The u-shaped linkage 842 and the link 844 operate to constrain the movement of the upper jaw 836 so that the second surface 826 associated with the jaw grip 838 does not rotate about an axis. The bias system 828 is comprised of a spring 850 that is located within a hole 852 of a housing 854. One end of the spring 850 is located adjacent to a cover 856 that is attached to the housing 854. The other end of the spring 850 contacts a surface associated with the upper jaw 836. In operation, the spring 850 applies a force to the upper jaw 836 such that the second surface 826 is forced towards the “closed” position. Other types of bias systems are also feasible. The grasper cam follower 830 is operatively attached to the upper jaw 836 and is comprised of a horizontal surface 860 and a transitional surface 862. The horizontal surface 860 interacts with the grasper cam driver associated with the crank assembly 806 to force the second surface 826 towards the “open” position, which is in opposition to the operation of the bias system 828. The transitional surface 826 interacts with the grasper cam driver associated with the crank assembly 806 so that there is a gradual transition of the second surface 826 between the “open” and “closed” positions. Associated with the grasper assembly 802 is a “tape-in-jaw” sensing system 868 that is comprised of a flag assembly 870 and a sensor 872. The flag assembly 870 is comprised of a spring-loaded plunger assembly 872. In operation, the plunger of the spring-loaded plunger 872 is in a first position if the grasping assembly 802 is not grasping a data cartridge. If, however, the grasping assembly 802 is grasping a data cartridge, the plunger moves to a second position. When the pusher plate assembly is at or near a fully retracted position, the sensor 872 can detect whether the plunger is in the first position or the second position. This information is used to determine which direction a crank associated with the crank assembly should be rotated. More specifically, if the grasper assembly 802 is grasping a data cartridge, the crank will be rotated in whichever direction, clock-wise or counter clock-wise, will maintain the grip on the data cartridge. If, the grasper assembly 802 is not grasping a data cartridge, the crank will be rotated in the opposite direction from that used to maintain a grip on a data cartridge. The pusher plate assembly 804 is comprised of: (a) a first member 880 that supports the gripper assembly 802 and comprises pusher plate cam follower; (b) an L-shaped member 882 that is operatively connected to the first member 880; (c) a linear rail 884 that is operatively connected to the base plate 800; (d) a pair of mounts 886A, 886B that connect the L-shaped member 882 to the linear rail 884; and (e) a roller assembly 888 that also connects the first member 880 to the base plate 800 and allows the first member 880 to move relative to the base plate 800. The linear rail 884 and pair of mounts 886A, 886B operate to constrain the movement of the gripper assembly 802 to linear movement towards and away from locations at which a data cartridge is located or can be located. Other types of base plate assemblies that are capable of being used to move a gripper assembly towards and away from locations at which a data cartridge is or can be located are feasible. The first member 800 comprises a pusher cam follower surface 894 that interacts with a pusher plate cam driver associated with the crank assembly 806 to move the pusher plate assembly 804 to a desired location along the linear rail 884. Generally, the cam follower surface 894 is comprised of two, parallel surfaces 896A, 896B. The application of a force by the pusher plate cam driver to the surface 896A drives the pusher plate assembly 804 away from the elevator 582. Conversely, the application of a force by the pusher plate cam driver to the surface 896B drives the pusher plate assembly 804 towards the elevator 582. Forming a portion of the surface 896A is a compliance member 898 that flexes to reduce the force being applied by the pusher plate cam driver to a data cartridge that has been contacted by the grasper assembly 802. In the illustrated embodiment, the compliance member 898 is comprised of a flat spring 900 that is located in a recess 902. One end of the spring 900 is fixed to the first member 880 and the other end of the spring 900 floats within the recess 902 to allow the spring 900 to flex. Forming a portion of the surface 896B is a dwell 904 that prevents the pusher plate cam driver from applying a force to the pusher plate assembly 804 over the extent of the dwell 898. The crank assembly 806 is comprised of: (a) a motor assembly 910 for providing a rotational motive force; (b) a crank 912 for rotating about an axis 913 in response to the rotational motive force provided by the motor assembly; and (c) a camming structure 914 that provides a grasper cam driver surface for interacting with a grasper cam follower and a pusher plate cam driver surface for interacting with a pusher plate cam follower, and moves through the operation of the motor assembly 910 and the crank 912. The motor assembly 910 is comprised of: (a) a stepper motor 920 that is attached to the base plate 800; and (b) a pinion 922 that is attached to the spindle of the stepper motor 920. The stepper motor 920 is capable of rotating the pinion 922 in a clock-wise direction and a counterclockwise direction. The crank 912 is comprised of: (a) a crank spindle 928 that is attached to the base plate 800; (b) a crank top 930; (c) an inner gear 932 that is attached to the crank top 930 and that engages the pinion 922 that is associated with the stepper motor 920; and (d) a bearing assembly 934 that connects the crank top 930 and the inner gear 932 to the spindle 928. The camming structure 914 is operatively attached to the crank top 930 and is comprised of a cylindrical surface 940 and a spherical surface 942. All or a substantial portion of the cylindrical surface 940 is the pusher plate cam driver surface that interacts with the pusher plate cam follower surface 894 to move the pusher plate assembly 804. The cylindrical surface 940 has a surface vector that is substantially perpendicular to the axis 913. Pusher plate cam driver surfaces that are other than cylindrical surfaces are feasible provided the surface is capable of interacting with a pusher plate cam follower surface to move the pusher plate to the desired location. At least a portion of the spherical surface 942 is the grasper cam driver surface that interacts with the grasper cam follower 830 to force the second surface 826 associated with the upper jaw 836 to move towards the “open” position. Associated with the crank assembly 806 is a crank position sensing system 948 that is comprised of: (a) a 50/50 flag 950 that is attached to the underside of the crank top 930 and used to determine whether the crank 912 is within a first 180 degree range of operation or a second 180 degree range of operation that does not substantially overlap with the first 180 degree range of operation; (b) a 50/50 flag sensor 952 for detecting the 50/50 flag; (c) a plurality of pins 954 that are attached to the underside of the crank top 930 and used to determine where the crank 912 is operating to a greater degree of accuracy than is possible with the 50/50 flag 950; and (d) an encoder sensor 956 for detecting pins associated with the plurality of pins 954. Also associated with the picker 580 is a calibration sensor 962 that is used to orient and/or calibrate the positioning systems within the library 100 by detecting the orientation structures 368A, 368B associated with the entry/exit port magazine 310, the top surfaces of the slit defining structures 418 of the magazines in the magazine structure 106, and drive orientation structures associated 964 (see FIG. 9B) with the frame 442 of the drive bay 108. Further associated with the picker 580 is a bar code sensor 966 that is used to detect a bar code that is associated with an entry/exit port magazine 310 and bar codes associated with data cartridges located within the library 100. With reference to FIGS. 15A1-15D2, the operation of the picker 580 in grasping an LTO data cartridge 980 is described. FIGS. 15A1 and 15A2 illustrate the situation in which: (a) the picker 580 has been positioned adjacent to the data cartridge 980 that is to be grasped; and (b) the pusher plate assembly 804 is fully retracted, i.e., the crank assembly 806 has been used to position the pusher plate assembly 804 as close to the elevator 582 as is possible. In this state, a portion of the spherical surface 942 is engaging the horizontal surface 860 of the grasper cam follower 830. As a consequence, the moving member 824 is positioned such that the second surface 826 and the first surface 822 are in the “open” position, i.e., incapable of grasping a data cartridge. Further, the flag assembly 870 of the tape-in-jaw sensory system 868 is in a state that indicates that there is no tape located between the first surface 822 and the second surface 826. FIGS. 15B1 and 15B2 illustrate the state of the picker 580 and the data cartridge 980 after the crank 912 has rotated the camming structure 914 in a counter-clockwise direction 984 though about 180 degrees relative to position of the camming structure 914 shown in FIGS. 15A1 and 15A2. The rotation of the camming structure 914 has caused the pusher plate cam driver portion of the cylindrical surface 940 to apply a force to the pusher cam follower surface 896A that has moved the pusher plate assembly 804 from the position shown in FIG. 15A1 to the position shown in FIG. 15A2. At this point, the spherical surface 942 is still engaging the horizontal surface 860 of the grasper cam follower 830. Consequently, the first surface 822 and the second surface 826 of the grasper assembly 802 are still in the “open” position. Since the data cartridge 980 is now in between the first surface 822 and the second surface 826, the flag assembly 870 is now in a state that indicates this condition. However, the flag assembly 870 is not yet positioned so that the plunger can be detected by the sensor 872. FIGS. 15C1 and 15C2 illustrate the state of the picker 580 and the data cartridge 980 after the crank 912 has slightly further rotated the camming structure 914 in the counter-clockwise direction 984 relative to the rotational position of the camming structure 914 shown in FIGS. 15B1 and 15B2. Due to the operation of the compliance member 898, the further rotation has resulted in little, if any, further linear displacement of the pusher plate assembly 804. The spherical surface 942 is, due to the further rotation, no longer in contact with the grasper cam follower 830. As a consequence, the bias system 828 has caused the second surface 826 to move towards the first surface 822 and the cartridge 980 to be grasped. The flag assembly 870 is still in a state that indicates that a cartridge is located between the first surface 822 and the second surface 826. Further, the flag assembly 870 is still not positioned so that the sensor 872 can detect the plunger associated with the assembly. FIGS. 15D1 and 15D2 illustrate the state of the picker 580 and the data cartridge 980 after the crank 912 has further rotated the camming structure 914 in the counter-clockwise direction 984 through about 180 degrees relative to position of the camming structure 914 shown in FIGS. 15B1 and 15B2, i.e. almost back to the fully retracted position. The further rotation of the camming structure 914 has caused the pusher plate cam driver portion of the cylindrical surface 940 to apply a force to the pusher cam follower surface 896B that has moved the pusher plate assembly 804 from the position shown in FIG. 15B1 to the position shown in FIG. 15D2. The spherical surface 942 is still not in contact with the grasper cam follower 830. As a consequence, the first surface 822 and the second surface 816 are still grasping the cartridge 980. The flag assembly 870 is still in a state that indicates that the cartridge is located between the first surface 822 and the second surface 826. However, the plunger associated with the flag assembly 870 is now positioned so that the sensor 872 can detect the plunger. The facts that the sensor 872 has detected that the data cartridge 980 is located between the first surface 822 and the second surface 826 and that the pusher plate assembly 804 is at or near to the fully retracted position dictate that any subsequent rotation of the crank 912 must be in the clockwise direction. Further rotation of the crank 912 in the counter-clockwise direction would result in the second surface 826 being displaced away from the first surface, which could result in the cartridge being dropped. Insertion of the grasped data cartridge into a location that is capable of holding the cartridge is accomplished by reversing the noted operations, which involves clockwise rotation of the crank 912. It should be appreciated that the picker 580 operates such that: (a) for a first range of the rotation of the crank 912, the grasper assembly 802 is in the open position and incapable of grasping a cartridge, and (b) for a second range of rotation of the crank 912 that does not substantially overlap with the first range, the grasper assembly 802 is in the closed position that allows a cartridge to be grasped. With reference to FIGS. 16A-16D, the ranges over which the grasper assembly 802 is in the open position, closed position, and transitioning between the open and closed positions are illustrated. FIG. 16A, which corresponds to FIGS. 15A1 and 15A2, illustrates the spherical surface 942 engaging the horizontal surface 860 of the grasper cam follower 830 at a point immediately adjacent to the transitional surface 862 of the grasper cam follower. Consequently, FIG. 16A illustrates an approximate first end point 990 of the first range of rotation of the crank 912 during which the grasper assembly 802 is in the open position. FIG. 16B, which corresponds to FIGS. 15B1 and 15B2, shows the spherical surface 942 engaging the horizontal surface 860 of the grasper cam follower 830 at point immediately adjacent to the transitional surface 862 after the crank 912 has rotated the camming structure 914 through approximately 180 degrees relative to the position of the camming structure 914 shown in FIG. 16A. At this point, the grasper assembly 802 is still in the open position. Consequently, FIG. 16B illustrates an approximate second end point 992 of the first range. As illustrated, the range between the first and second end points 990, 992, relative to a center line 994, is somewhat less than 180 degrees. With reference to FIG. 16C, which corresponds to FIGS. 15C1 and 15C2, the spherical surface 942 is not engaging the grasper cam follower 830 and is positioned at a point immediately adjacent to the transitional surface 862. At this point, the grasper assembly 802 is in the closed position. Consequently, FIG. 16C illustrates an approximate first end point 996 of the second range of rotation of the crank 912 during which the grasper assembly 802 is in the closed position. FIG. 16D, which corresponds to FIGS. 15D1 and 15D2, shows the spherical surface 942 immediately adjacent to the transitional surface 862 of the grasper cam follower 830 after the crank 912 has rotated the camming structure 914 through approximately 180 degrees relative to the position of the camming structure 914 shown in FIG. 16C. Consequently, FIG. 16D illustrates an approximate second end point 998 of the second range. As illustrated, the range between the first and second end points 996, 998, relative to a center line 994, is somewhat less than 180 degrees. Between the second end point 992 of the first range and the first end point 996 of the second range, the spherical surface 942 is engaging the transitional surface 862 of the grasper cam follower 830 and the grasper assembly 802 is between the open and closed positions. Similarly, between the second end point 998 of the second range and the first end point 990 of the first range, the spherical surface 942 is engaging the transitional surface 862 of the grasper cam follower 830 and the grasper assembly 802 is between the open and closed positions. When the grasper assembly 802 is between the open and closed positions, the ability of the grasper assembly 802 to grasp a cartridge is ambiguous. Consequently, the end points of the first and second ranges may lie in the ranges associated with the transition of the grasper assembly 802 between the open and closed positions. As such the first and second ranges may lie closer to 180 degrees or may exceed 180 degrees. In any event, the ranges are each approximately 180 degrees and do not substantially overlap. It should be appreciated that picker can be designed such the grasper is in an open position for a first range of rotation of a crank and in a closed position for a second range of rotation of the crank that does not substantially overlap with the first range of rotation where the ranges are different than those illustrated in FIGS. 16A-16D. With reference to FIGS. 12B, 13A and 13B, the library 100 further comprises a removable robotics module 740 that allows a user to readily remove substantially all of the electrical and mechanical components of the transport system 112 that could break or malfunction from the library 100 and replace all of those components by inserting another module into the library 100. As a consequence, any downtime for the library 100 that is associated with a broken or malfunctioning component of the transport system 112 can be reduced. The removable robotic module 740 comprises the robotic module tray 670 and, attached to the tray 670, the picker 580, most of the elevator 582, and a controller board 742 that provides control logic for the picker 580 and the elevator 582. The module 740 does not include the pulley 692, the bracket 694, the second shaft pulley 696, the bracket 698, the third timing belt 700, the portion of the connecting bracket 690 that remains connected to the timing belt 700 after the quick release device is actuated, the second shaft piece 704, or the spline sleeve 708. The tray 670 of the module 740 is fixed in place in the library 100 by brackets 744A-744B that are attached to the side portion 184A of the bottom tray 186, brackets 746A-746B that are attached to the side portion 184B of the bottom tray 186, a bracket 748 that is attached to the mid-portion 190 of the bottom tray 186, and a threaded hole 750 that receives a captured screw 752 associated with the tray 670. The brackets 744A, 744B, 746A and 746B operate to engage the edge of the tray 670 and thereby vertically constrain the tray 670. The bracket 748 engages the edge of the tray 670 to both vertically and horizontally constrain the tray 670. The threaded hole 750, when engaged by the screw 752, also serves to vertically and horizontally constrain the tray 670. Assuming the removable robotic module 740 is fixed in place within the library 100, removal of the module 740 involves: removing the front panel 176 to expose the module 740, unscrewing the screw 752 from the threaded hole 750, manipulating the spline sleeve 708 to disconnect the first shaft piece 702 and the second shaft piece 704, and manipulating the connecting bracket 701 to disconnect the top plate 622 from the third timing belt 700. In addition, an electrical connector that connects the controller board 742 and the control module 536 is disconnected. After these operations are completed, the module 740 can be slid out of the library 100 and, if desired, a replacement module inserted and connected to the library. After any replacement module has been connected to the library 100, the front panel 176 is replaced. The foregoing is intended to describe the best mode known of practicing each of the inventions and to enable others skilled in the art to practice the inventions.

<SOH> BACKGROUND OF THE INVENTION <EOH>Presently, data cartridge libraries are primarily used to archive data, i.e., store data that is not immediately needed by a host computer, and provide archived data to the host computer when the data is needed. To elaborate, the typical data cartridge library receives data from a host computer and causes the data to be stored or recorded on the recording medium located in one or more cartridges. When the host computer requires some of the data that was previously stored in a data cartridge, a request for the data is sent from the host computer to the library. In response, the library identifies the data cartridge(s) in which the desired data is located, retrieves the data from the recording medium with the cartridge(s), and transmits the retrieved data to the host computer system. Presently, most data cartridge libraries are comprised of: (a) a frame/chassis/cabinet that defines an interior space; (b) a magazine structure that is located within the interior space and that provides a plurality of data cartridge storage spaces, which are each capable of accommodating at least one data cartridge; (c) one or more drives that are each located within the interior space and capable of writing data onto a recording medium located in a data cartridge and/or reading data from the recording medium located in a data cartridge; (d) a data cartridge transport device that is located within the interior space and capable of moving an individual data cartridge between any one of the plurality of data cartridge storage spaces and any one of the drives within the library; and (e) an interface for receiving data from and transmitting data to a host computer. Typically, such a data cartridge library is capable of both storing data provided by a host computer and retrieving data previously stored in the library for the host computer. The storage of data involves using the transport device to move a data cartridge from one of the data cartridge storage spaces to a drive, using the drive to write the data provided by the host computer on the recording medium located within the cartridge, and after the data has been written on the recording medium, using the transport device to move the data cartridge from the drive to a data cartridge storage space. The retrieval of data involves using the transport device to move a data cartridge from one of the data cartridge storage spaces to a drive, using the drive to read the data on the recording medium located within the cartridge and provide the read data to the host computer, and after the data has been read from the recording medium, using the transport device to move the data cartridge from the drive to a data cartridge storage space. As previously noted, a data cartridge library is comprised of a data cartridge transport that is capable of being used to move a data cartridge between any one of the magazine data cartridge storage locations and any one of the drives in the library. Typically, the data cartridge transport device is comprised of a picker and an elevator that moves the picker within the interior space. The picker is capable of inserting/extracting a data cartridge into/from any one of the magazine storage spaces and any one of the drives. Typically, the picker is comprised of: (a) a grasping device that is used to engage a data cartridge and (b) a pusher plate that carries the grasping device and that is capable of movement towards and away from a location that is capable of accommodating a data cartridge. The elevator serves to position the picker adjacent to a location that is capable of accommodating a data cartridge so that the picker can perform an insertion or extraction operation. In an extraction operation, the elevator is used to position the picker adjacent to a space at which a data cartridge is located (typically, either a storage space associated with the magazine or a drive). After the picker has been positioned, the pusher plate is used to move the grasping device towards the data cartridge. After the grasping device has been positioned, the grasping device is then actuated to grasp the cartridge. At this point, the pusher plate is then moved away from the location at which the data cartridge was located to extract the data cartridge from the space. In an insertion operation, the elevator is used to position the picker (which is assumed to be grasping a data cartridge) adjacent to the space at which a data cartridge is to be located. After the picker has been positioned, the pusher plate is then used to move the grasping device and the grasped data cartridge towards the space in which the data cartridge is to be located. After the pusher plate and grasping device have positioned the data cartridge in the space, the grasping device releases the data cartridge, and the pusher plate is moved away from the space to retract the grasping device. Many data cartridge libraries are also comprised of an entry/exit port that allows a user to insert and/or extract a data cartridge from the library without powering down the transport device. To elaborate, absent an entry/exit port, if a user wants to insert/extract a data cartridge into/from a library, the user typically powers down the transport device to avoid being injured by the transport device during the insertion or extraction of the data cartridge. The entry/exit port allows a user to insert/extract a data cartridge into/from the library without being exposed to the transport device. As a consequence, the entry/exit port allows a data cartridge to be inserted/extracted into/from the library without having to power down the transport device. Typically, an entry exit port is comprised of a slot structure that defines at least one slot that is capable of accommodating at least one data cartridge and a device that places the structure in one of two states. In the first state, the device positions the slot structure such that a slot is exposed to the exterior environment. When the structure is in this state, a user can either insert a data cartridge into the slot or remove a data cartridge from the slot, without being exposed to the transport device in either case. In the second state, the device positions the slot structure such that a slot is exposed to the interior of the library and accessible by the transport device, which can either insert a cartridge into the slot or remove a cartridge from the slot. When the structure is in the second state, the user is not exposed to the transport device. One type of entry/exit port that has evolved is comprised of: (a) a frame or support to/from which a magazine that can accommodate multiple data cartridges can be attached/detached; and (b) a device for placing the frame in one of the states. In the first state, the device positions the frame such that the frame is exposed to the exterior environment. When the structure is in this state, a user can either attach a magazine to the frame or detach a magazine from the frame. Further, the user can either insert/remove one or more data cartridges into/from the magazine. In the second state, the device positions the frame such that any magazine that is attached to the frame is exposed to the transport device. In this state, the transport device can load data cartridges into the magazine or remove data cartridges from the magazine, as needed. When the frame is in either state, a user is substantially shielded from the transport device. Many data cartridge libraries also have a hinged door that allows a user access to the interior of the library. Typically, such a door is provided so that the transport device can be accessed for maintenance and repair.

<SOH> SUMMARY OF THE INVENTION <EOH>The present invention is directed to a data cartridge library that is comprised of: (a) a frame/chassis/cabinet; (b) a data cartridge magazine that provides a plurality of data cartridge storage spaces that are each capable of accommodating at least one data cartridge; (c) a drive that is capable of writing data onto a recording medium located within a cartridge and/or reading data from a recording medium located in a cartridge; (d) a picker that is capable of being used to insert and extract a data cartridge from a space that is capable of accommodating a data cartridge; and (e) an elevator for moving the picker within the library so that a data cartridge can be transported between any one of the plurality of magazine data cartridge storage spaces and any one of the drives within the library. In one embodiment, the data cartridge library comprises a picker that is comprised of: (a) a base plate that is operatively connected to an elevator; (b) a grasper that is operatively connected to the base plate and comprised of a pair of members that are capable of being placed in a closed position that is suitable for grasping a data cartridge and an open position that is suitable for releasing a grasped data cartridge; and (c) a crank that is operatively connected to the base plate and capable of rotating about an axis. The picker further comprises a grasper cam structure comprised of a cam driver that is associated with the crank and a cam follower that is associated with the grasper. The cam driver and the cam follower are situated such that rotation of the crank brings the cam driver into contact with the cam follower and, in so doing, places the grasper in one of the closed position and the open position. Unlike known pickers that employ a crank and a cam structure to actuate a grasper, the grasper is placed in a closed position over a first range of rotation of the crank and an open position over a second range of rotation of the crank that substantially does not overlap with the first range of rotation. In one embodiment, the first and second ranges are each about 180 degrees. In one embodiment, the data cartridge library comprises a picker that is comprised of: (a) a base plate that is operatively connected to an elevator; (b) a grasper that is operatively connected to the base plate and comprised of a pair of members that are capable of being placed in a closed position that is suitable for grasping a data cartridge and an open position that is suitable for releasing a grasped data cartridge; and (c) a crank that is operatively connected to the base plate and capable of rotating about an axis. The picker further comprises a grasper cam structure comprised of a cam driver that is associated with the crank and a cam follower that is associated with the grasper. The cam driver and the cam follower are situated such that rotation of the crank brings the cam driver into contact with the cam follower and, in so doing, places the grasper in one of the closed position and the open position. Unlike known pickers that employ a crank and a cam structure to actuate a grasper, the crank is capable of rotating through more than 180 degrees. In one embodiment, the crank is capable of rotating through 360 degrees. In a particular embodiment in which the crank is capable of such a rotation, the picker is further comprised of a pusher plate that supports the grasper and a pusher plate cam structure that is used to move the pusher plate towards and away from a space that is capable of accommodating a data cartridge. The pusher plate cam structure is comprised of a pusher plate cam driver that is associated with the crank and a pusher plate cam follower that is associated with the pusher plate. The grasper cam structure and pusher cam structure are situated such that: (a) for 180 degrees of a 360 degree rotation of the crank, the grasper is placed in a closed position and the pusher plate can be moved between a fully retracted and a fully extended position; and (b) for the other 180 degrees of a 360 degree rotation of the crank, the grasper is placed in an open position and the pusher plate can be moved between a fully retracted position and a fully extended position. In another embodiment, the data cartridge library is comprised of a picker that is, in turn, comprised of a base plate, grasper, crank that is capable of rotation about an axis, and a grasper cam structure. The grasper cam structure is comprised of a cam driver that is associated with the crank and a cam follower that is associated with the grasper. The grasper cam driver has a surface vector that is not substantially perpendicular to the axis or rotation of the crank. In one embodiment, the grasper cam driver comprises a bubble-like or spherical section that has such a surface vector. In a further embodiment, the picker is comprised of a pusher plate and a pusher plate cam structure with a pusher plate cam driver that is associated with the crank. The pusher plate cam driver has a surface vector, in contrast to the grasper cam driver, that is substantially perpendicular to the axis of rotation of the crank. In one particular embodiment, the pusher plate cam structure operates to move the pusher plate in a direction that is substantially perpendicular to the axis of rotation of the crank and the grasper cam structure operates such that the grasper cam follower is displaced in a direction that at least has a component vector that is parallel to the axis of rotation of the crank. In another embodiment, a data cartridge library is provided that allows a user to readily remove/insert a transport module from/into the library, where the transport module is comprised of a picker and a substantial portion of an elevator. In one embodiment, the library is comprised of: (a) a frame/chassis/cabinet; (b) a data cartridge magazine; (c) a drive; (d) a picker that is capable of being used to insert and extract a data cartridge from a space that is capable of accommodating a data cartridge; and (e) an elevator for moving the picker within the library so that a data cartridge can be transported between any one of the plurality of magazine data cartridge storage spaces and any one of the drives within the library. The library is further comprised of a transport module that is comprised of a support structure, a portion of the elevator that is connected to the support structure, and the picker. A user-actuatable connector is also provided that allows a user to attach the transport module to the frame of the library and to detach the transport module from the frame so that the module can be removed from the library. In one embodiment of a data cartridge library with a removable/insertable transport module, the elevator is comprised of an elevator carriage that supports the picker, a first drive system for driving one end of the carriage, a second drive system for driving the other end of the carriage, an electric motor that is operatively connected to the first drive system and provides the first drive system with energy for moving the first end of the carriage. The elevator is further comprised of a shaft that connects the first drive system to the second drive system, thereby allowing energy from the motor to be transferred through the first drive system to the second drive system. So that the transport module can be removed from the library, the shaft is capable of be separated into two pieces by actuation of a user-actuatable connector. In one embodiment, the connector is comprised of a spline associated with a free end of one piece of the shaft and a spline collar that is associated with the free end of the other piece of the shaft. By sliding the spline collar away from the spline, the two pieces of the shaft are disconnected to facilitate removal of the transport module from the library. To connect the two pieces of the shaft, the free ends of the shaft are aligned and the spline collar is slide over the spline. In yet another embodiment, a data cartridge library is provided in which a shaft, rather than a pulley system, is used to connect two drive structures that are used to drive the ends of an elevator carriage that supports a picker. In one embodiment, the library is comprised of: (a) a frame/chassis/cabinet; (b) a data cartridge magazine; (c) a drive; (d) a picker that is capable of being used to insert and extract a data cartridge from a space that is capable of accommodating a data cartridge; and (e) an elevator for moving the picker within the library so that a data cartridge can be transported between any one of the plurality of magazine data cartridge storage spaces and any one of the drives within the library. The elevator is comprised of an elevator carriage that supports the picker, a first drive system for driving one end of the carriage, a second drive system for driving the other end of the carriage, an electric motor that is operatively connected to the first drive system and provides the first drive system with energy for moving the first end of the carriage. The elevator is further comprised of a shaft that connects the first drive system to the second drive system, thereby allowing energy from the motor to be transferred through the first drive system to the second drive system. In yet another embodiment, a data cartridge library is provided with a door that allows a user access to the interior of the library and that is not constrained to rotate about an axis when moving between open and closed positions. In one embodiment, the library is comprised of: (a) a frame/chassis/cabinet with a top surface, bottom surface, and side surface extending between the top and bottom surfaces; (b) a data cartridge magazine; (c) a drive; (d) a picker that is capable of being used to insert and extract a data cartridge from a space that is capable of accommodating a data cartridge; and (e) an elevator for moving the picker within the library so that a data cartridge can be transported between any one of the plurality of magazine data cartridge storage spaces and any one of the drives within the library. The library is further comprised of a user interface that is associated with the side surface of the frame and is exposed to the exterior environment. In various embodiments, the user-interface comprises an output terminal for providing a user with information relating to the library, an input terminal for allowing a user to interact with the library, an entry/exit port, and combinations of the these elements. The side surface is comprised of a displaceable portion that accommodates the user interface. The displaceable portion is capable of being placed in an “open” condition that allows a user access to the magazine, drive(s), picker and elevator and a “closed” condition that prevents user access to the noted elements. The library further comprises a user-actuatable connector that permits a user to place the displaceable portion in either the open or closed conditions. However, unlike hinged doors, the displaceable portion and the user-actuatable connector do not constrain the displaceable portion to rotate about an axis in moving between open and closed positions. In one embodiment, the user-actuatable connector comprises one or more captured screws that allow the displaceable portion to be detached from the frame to expose the interior of the library or attached to the frame to cover the interior of the library. In another embodiment, a data cartridge library is provided that has a multi-piece magazine. In one embodiment, the library is comprised of: (a) a frame/chassis/cabinet; (b) a data cartridge magazine; (c) a drive; (d) a picker that is capable of being used to insert and extract a data cartridge from a space that is capable of accommodating a data cartridge; and (e) an elevator for moving the picker within the library so that a data cartridge can be transported between any one of the plurality of magazine data cartridge storage spaces and any one of the drives within the library. In one embodiment, the magazine is a multi-piece structure that forms a channel with a first side, a second side, and a back side that extends between the first and second sides. The first, second and back sides cooperatively define an interior space that is capable of accommodating a plurality of data cartridges. The multi-piece magazine structure is comprised of: (a) a first structure that is in the form of a U-shaped channel that forms portions of the first and second sides of the magazine and the back side of the magazine; (b) a second structure that forms portions of the first and second sides; and (c) a coupler for connecting the first and structures to one another. The first structure also serves as a portion of the frame of the library and, in one embodiment, is made of metal. The second structure is made of the same type of material as the cartridges (typically, plastic) in one embodiment. The present invention further provides a multi-piece magazine that is suitable for use in a data cartridge library. In one embodiment, the magazine resulting for the joining together of the various pieces forms a channel with a first side, a second side, and a back side that extends between the first and second sides. The first side, second side and back side cooperatively define an interior space that is capable of accommodating a plurality of data cartridges. The multi-piece magazine structure is comprised of: (a) a first structure that forms at least a portion of the back side of the magazine; (b) a second that structure that forms at least portions of the first and second sides; and (c) a coupler for connecting the first and second structures to one another. In one embodiment, the first structure is in the form of a U-shaped channel that forms portions of the first and second sides of the magazine and a substantial portion of the back side of the magazine. The second structure, in addition to providing at least portions of the first and second sides of the magazine, further comprises a pair of end sides that are separated from each other and that each connect the portions of the first and second sides provided by the second structure to one another, thereby forming a closed-loop structure. The coupler connects the first and second structures to one another so as to form a box-like, magazine structure with an open side through which cartridges can be inserted/removed into/from the magazine structure. The present invention also provides a magazine that is capable of being attached/detached to/from an entry/exit port structure. The magazine is comprised of: (a) a box structure with a bottom wall and a side wall that extends from the bottom wall to a terminal edge that defines an opening for the insertion/extraction of data cartridges into/from the magazine; (b) a plurality of partitioning structures that partition the interior space of the magazine into a plurality of slots that are each capable of accommodating at least one data cartridge; and (c) a coupling structure that allows the box structure to be attached/detached to/from an entry/exit port structure. In one embodiment, the coupling structure is comprised of a first substantially rigid flange that extends away from a first side wall portion and a second substantially rigid flange that extends away from a second side wall portion that is separated from and substantially parallel to the first side wall portion. In one embodiment, the first and second flanges are located in an asymmetric manner so that the box structure can only be mounted to the entry/exit port structure in a particular orientation. The present invention further provides a data cartridge library with an entry/exit port that has a frame that can be readily attached and detached to facilitate maintenance of the entry/exit port. In one embodiment, the library is comprised of: (a) a frame/chassis/cabinet; (b) a data cartridge magazine; (c) a drive; and (d) a transport assembly that is capable of moving a data cartridge between any one of the plurality of magazine data cartridge storage spaces and the drive. The library is further comprised of an entry/exit port for moving entry/exit port magazines between an exterior environment and an interior environment of the library where the magazine is accessible to the transport device. In one embodiment, the entry/exit port comprises a mount to which a magazine can be attached and from which a magazine can be detached, a guide structure for constraining the movement of the mount between a first position at which a user can attach/ detach a magazine to/from the mount and a second position at which the transport assembly is capable of inserting/removing a data cartridge into/from a magazine attached to the mount, and a motive device for providing the motive force for moving the mount between the first and second positions. The entry/exit port further comprises a “stop” structure that is attached to the mount and operates to prevent the mount from being moved beyond the first position. A quick release structure allows the stop structure to be quickly detached from the mount so that the mount can be readily removed from the library. The present invention also provides a data cartridge library with a drive bay that is capable of accommodating a full-height drive and being altered to accommodate two, half-height drives. In one embodiment, the library is comprised of: (a) a frame/chassis/cabinet; (b) a data cartridge magazine; and (c) a transport assembly that is capable of moving a data cartridge between any one of the plurality of magazine data cartridge storage spaces and any one of the drives within the library. The library is further comprised of a drive bay that provides a full-height drive space that is capable of accommodating a full-height drive and a partition mount for supporting a partition that allows the full-height drive space to be divided into two, half-height drive spaces that are each capable of accommodating a half-height drive. In one embodiment, the full-height drive space is capable of: (a) accommodating a full-height drive that is located within a full-height drive sled; or (b) when a partition engages the partition mount, accommodating two, half-height drives that are each located within a half-height drive sled. In other embodiments, the library is further comprised of combinations of full-height and half-height drives located in the drive bay. The present invention also provides a data cartridge library with a universal bay that is capable of accommodating one of more electronic devices that are not necessary to the operation of the library but can be used to enhance or supplement the operation of the library. In one embodiment, the library is comprised of a frame/chassis/cabinet that defines an interior space. The interior space is partitioned into: (a) a data cartridge space that provides storage locations for all of the cartridges that the library is capable of storing; (b) a drive space that provides locations for all of the drives that the library is capable of supporting; (c) a transport assembly space for accommodating the movement of a picker and elevator in moving a data cartridge between any one of the data cartridge storage locations and any one of the drives within the library; (d) a power supply space for housing all of the power supplies that the library is capable of supporting; and (e) circuitry space for housing circuitry that is used to distribute power within the library and control the operation of the transport assembly. The library is further comprised of a universal bay that defines a universal space which can be used to house circuitry other than the circuitry located in the circuitry space and does not comprise any of the other noted spaces. In one embodiment, the universal bay comprises a partition mount that is capable of supporting a partition that is used to divide the universal space into subsidiary spaces, each capable of accommodating circuitry that enhances or supplements the operation of the library.

20040305

20060905

20050908

62237.0

EVANS, JEFFERSON A

MODULAR ROBOTICS SYSTEM FOR A DATA CARTRIDGE LIBRARY

SMALL

ACCEPTED

ACCEPTED

SECURITY SESSION AUTHENTICATION SYSTEM AND METHOD

Sharing of data between one domain and at least one other domain over a network is facilitated by the use of tokens. A user token set in a cookie stored on the user's system at log-on to a first domain is used to create, or is associated with, a secure token passed by a first domain to a second domain when the user, in a session with the second domain, requests resources, access to which includes authorization by a first domain. The secure token facilitates various actions pertinent to a user in a session with said second domain, including, for example, the maintenance of an active, concurrent session between a user and a first domain, and authentication and authorization without log-on at a second domain or other domains.

1. A method for facilitating the sharing of data pertinent to a user system between a first domain and a second domain, wherein said second domain is in a session with said user system, the method comprising: establishing a network session between said user system and said second domain, wherein said session is at least one of secure or non-secure, and wherein said second domain and said first domain are configured to interactively communicate with each other; receiving a request from said user system to said second domain for a resource, wherein access to said resource includes authorization by said first domain; determining the presence of at least one secure token in a cookie set by said second domain on said user system, wherein said secure token originates with said first domain and relates at least to an authorization of said user system to access said resource; determining the validity of said secure token, if said secure token is present; redirecting said request to said first domain, if said secure token is not present; and if said secure token is present, and is valid, incorporating said secure token in a request to said first domain to keep the state of the session between said user system and said first domain as active. 2. The method of claim 1, wherein said secure token is encrypted, and is clarified by at least one of said first domain and second domain prior to its use in said request to maintain the session between said user system and said first domain. 3. The method of claim 1, wherein said secure token is obfuscated, and is clarified by at least one of said first domain and second domain prior to its use in said request to maintain the session between said user system and said first domain. 4. The method of claim 1, further comprising determining an elapsed time since the prior use of said secure token in said request to maintain the session between said user system and said first domain, and if such elapsed time is greater than a pre-defined threshold, redirecting said user system to said first domain. 5. The method of claim 1, further comprising using said secure token, if such secure token is present, and is valid, to fulfill said request made by said user system for said resource. 6. The method of claim 1, further comprising determining whether said request made by said user system is for a secure or a non-secure resource, and if said request is for a non-secure resource, fulfilling said request. 7. A computer system for facilitating the sharing of data pertinent to a user system between a first domain and a second domain, wherein said second domain is in a session with said user system, comprising: a module configured to establish a network session between said user system and said second domain, wherein said session is at least one of secure or non-secure; a module configured to establish interactive communication between said first domain and said second domain; a module configured to receive a request made by said user system to said second domain for a resource, wherein access to said resource includes authorization by said first domain; a module configured to substantially determine the presence of at least one secure token in a cookie set by said second domain on said user system, wherein said secure token originates with said first domain and relates at least to an authorization of said user system to access said resource; a module configured to substantially determine the validity of said secure token, if said secure token is present; a module configured to redirect said request to said first domain, if said secure token is not present; and if said secure token is present, and is valid, a module configured to use said secure token in a request to said first domain to keep the state of the session between said user system and said first domain as active. 8. The system of claim 7, further comprising a module to clarify said secure token, where said secure token is obfuscated, prior to its use in said request to said first domain to keep the state of the session between said user system and said first domain as active. 9. The system of claim 7, further comprising a module to decrypt said secure token, where said secure token is encrypted, prior to its use in said request to said first domain to keep the state of the session between said user system and said first domain as active. 10. The system of claim 7, further comprising a module configured to substantially determine an elapsed time since the prior use of said secure token in said request to said first domain to keep the state of the session between said user system and said first domain as active, and if such elapsed time is greater than a pre-defined threshold, to redirect said user system to said first domain. 11. The system of claim 7, further comprising a module configured to use said secure token, if such secure token is present, and is valid, to fulfill said request for said resource. 12. The system of claim 7, further comprising a module configured to substantially determine whether said request is for a secure or a non-secure resource, and if said request is for a non-secure resource, fulfilling said request. 13. A method for facilitating the sharing of data pertinent to a user system between a first domain and a second domain, wherein said second domain is in a session with said user system, the method comprising: establishing a network session between said user system and said second domain, wherein said session is at least one of secure or non-secure, and wherein said second domain and said first domain are configured to interactively communicate with each other; receiving, on redirect from said second domain, a request made by said user system to said second domain for a resource, wherein access to said resource includes authorization by said first domain; determining the presence of at least one user token in a cookie set by said first domain on said user system, wherein said user token originates with said first domain and relates at least to a log-on of said user system to said first domain; determining the validity of said user token, if said user token is present; if said user token is at least one of not present and not valid, said user system logging-on, and, upon valid log-on, setting a user token in a cookie on said user system, which user token relates at least to said log-on; and if said user token is present, and said user token is valid, including a secure token in said first domain response to said redirect from said second domain, wherein said secure token relates to the authorization of said user system to request said resource. 14. The method of claim 13, wherein said secure token included in said first domain's response to said redirect from said second domain is obfuscated. 15. The method of claim 13, wherein said secure token included in said first domain's response to said redirect from said second domain is encrypted. 16. The method of claim 13, further comprising: receiving a request from said second domain, wherein said request is to keep the state of the session between said user system and said first domain as active; determining whether said request made by said second domain contains said secure token; and if said secure token is present, and is valid, setting the state of the session between said first domain and said user system as active. 17. The method of claim 13, further comprising determining whether said request made by said user system is for a secure or a non-secure resource, and if said request is for a non-secure resource, including a secure token in said first domain's response to said redirect from said second domain authorizing fulfilling said request whether or not said user token is present. 18. A computer system for facilitating the sharing of data pertinent to a user system between a first domain and a second domain, wherein said second domain is in a session with said user system, comprising: a module configured to establish a network session between said user system and said first domain, wherein said session is at least one of secure and non-secure; a module configured to facilitate interactive communication between said first domain and said second domain; a module configured to receive, on redirect from said second domain, a request made by said user system to said second domain for a resource, wherein access to said resource includes authorization by said first domain; a module configured to substantially determine the presence of at least one user token in a cookie set by said first domain on said user system, wherein said user token originates with said first domain and relates at least to a log-on of said user system to said first domain; a module configured to substantially determine the validity of said user token, if said user token is present; if said user token is at least one of not present and not valid, said user system logging-on, and, upon valid log-on, setting a user token in a cookie on said user system, which token relates at least to said log-on; and if said user token is present, and is valid, a module configured to include a secure token in said first domain's response to said redirect from said second domain, wherein said secure token relates to the authorization of said user system to request said resource. 19. The system of claim 18, further comprising a module to obfuscate said secure token prior to inclusion in said first domain's response to said redirect from said second domain. 20. The system of claim 18, further comprising a module to encrypt said secure token prior to inclusion in said first domain's response to said redirect from said second domain. 21. The system of claim 18, further comprising: a module to receive a request from said second domain, wherein said request is to keep the state of the session between said first domain and said user system as active; a module to substantially determine whether said request contains said secure token; and if said secure token is present in said request, and said token is valid, setting the state of said session between said first domain and said user system as active. 22. A secure token comprising computer readable program code relating at least to the authorization of a user system in a session with a second domain, which session is one of secure or non-secure, to access a resource, wherein access to said resource includes authorization by a first domain, and wherein said computer readable program code derives from a secure token included by said first domain in a response to a redirect by said second domain of a request for said resource, which secure token is included in a cookie set by the second domain on the user system, and wherein said secure token is associated with a user token in a cookie set by said first domain on said user system at log-on to said first domain. 23. The secure token of claim 22, wherein said secure token is obfuscated by said first domain prior to inclusion in said first domain's response to said redirect from said second domain. 24. The secure token of claim 22, wherein said secure token is encrypted by said first domain prior to inclusion in said first domain's response to said redirect from said second domain. 25. A method for facilitating the sharing of data pertinent to a user system between a first domain and a second domain, wherein said second domain is in a session with said user system, the method comprising: establishing a network session between said user system and said second domain, wherein said session is at least one of secure or non-secure, and wherein said second domain and said first domain are configured to interactively communicate with each other; receiving a request from said user system to said second domain for a resource, wherein access to said resource includes authorization by said first domain; requesting, by said second domain, authentication of said user session at said first domain; determining the validity of said authentication, if said authentication is present; redirecting said request to said first domain, if said authentication is not valid; and if said authentication is valid, maintaining the state of the session between said user system and said first domain as active.

FIELD OF INVENTION The method and system of this invention generally relates to network communications, and more particularly, to facilitating the sharing of data between one domain and at least one other domain, by the use of tokens, to facilitate various actions pertinent to a user in a session with the other domain, including, for example, authentication, authorization, and the maintenance of an active, concurrent session over the network between a user and the first domain. BACKGROUND OF INVENTION It is increasingly common for transactions and services to be provided by electronic means. The conduct of such business to business and business to consumer transactions and the delivery of services is often facilitated by a user connecting to a host or server on the World Wide Web. In providing transactions and services to the user or client, the host may need to marshal resources, including applications and data, hosted at related servers or on third party servers. For example, an on-line store may offer a user the opportunity to browse and purchase products offered by multiple vendors. The store may need to display products and prices derived from such vendors' servers, process a purchase or sale transaction, and provide for payment and shipping. In accessing such resources, a connection is typically established with, or request made to, the server hosting the requested resource. Where the resource is partially or fully secure, it may be available only following log-on by the user and the establishment of a secure session with the server where the secure application or data resides. The log-on may provide authentication of the user and verification of the authorization of the user to access the requested resource. Log-on may be effected by supplying a user name and password which matches a user name and password previously established with the server hosting the resource, and sometimes additionally by the successful completion of a challenge query and a proper response sequence. The requirement of sign-in, authentication, and authorization in order to obtain secure content may interrupt the perceived continuity of the session established between the user and the host. The user may be requested to engage in the authentication and authorization process multiple times, such as by logging-on, with the host and third party servers, in order to access applications and data. Each log-on may include a different user name or identification and password. The interruption of the session with the host, and the possible need to retain multiple user names and passwords, detracts from the user experience. Moreover, the session with one server may expire or time-out, thereby requiring the user to log-on again. Methods exist to avoid multiple authentication and authorization steps by the user, while merging the functionality and resources of more than one site. Some such methods are referred to as “single sign-on” or SSO. Such methods generally include the use of a central authentication service which stores user identities and authorizations for various servers. The user typically logs-on once with the service, and may then access the applications and data for which authorization has been supplied by the service. The service may host the user session by providing a single log-on and negotiating for access to secure data with other web servers participating in the service. This solution to multiple user log-on is often complicated and expensive to deploy and maintain. An example of single-sign-in methodology is Microsoft Corporation's Passport® single sign-in protocol, which provides users a means to sign-in to participating merchant web sites by signing-in and being authenticated only once to a common server. The Passport® protocol relies upon encrypted cookies set by the Passport® server. When a user begins a session with a merchant web site, the merchant web site re-directs the user to a Passport® server. The user logs-on with the Passport® server, and the Passport® server returns encrypted authentication information which is set as a cookie with the user system. Such authentication information can only be decrypted by the merchant web site. When the user returns to the merchant web site, the encrypted cookie is also returned to the merchant web site. The cookie is decrypted at the merchant web site and the user is verified as authenticated. The Passport® server also sets a cookie by which it can recognize the user as logged-in. Thus, if the user visits a second merchant web site, on re-direct to the Passport® server the Passport® server recognizes the user as already logged-in, and does not require another log-on, but returns authentication information that can only be decrypted by the second merchant web site, and redirects the user to that web site. Current approaches to multiple authentication and authorization may include the sharing of confidential information about the user with the third party authentication service, and the necessity of updating such information on both the server owning the information and the third party server providing the authentication service. The placement of proprietary databases containing user information with a third party server also increases security risks. Accordingly, a need exists for a less complicated and more cost effective way to address the requirement of sign-in, authentication, and authorization for multiple servers. SUMMARY OF INVENTION A method and apparatus facilitates the sharing of data between one domain and at least one other domain over a network, by the use of at least one token created by the first domain. The first domain and the other domain, herein referred to as the second domain, are capable of interactively communicating with each other. While in a session with the second domain, the user requests a resource, access to which is controlled or includes authorization by the first domain. The resource may be hosted at the second domain, the first domain or another domain, and which resource may be at least one of secure and non-secure. The second domain initially redirects the user request to the first domain, and the first domain authenticates the user, said authentication including at least determining whether the user has previously established a user session by logging-on with the first domain, and, if not logged-on, may requesting the user to log-on with the first domain; determining whether the user session is still valid, for instance, has not expired or timed out; and determining what resources the user is authorized or permitted to access. The process of authenticating the user includes at least verifying the presence on the user system of a user token set by the first domain at the time the user logged-in to the first domain. If the user token is present, and the first domain determines the user token to be substantially authentic and valid, for instance, not expired or timed-out, and the user request to be within the authorization of the user established at log-on, the first domain uses the user token to create a secure token and places the secure token in a header to the first domain's response to the redirect of the user. The secure token may include a form of the user token, or may be created in some other manner that allows the secure token to be associated with the authenticated user in subsequent communications. The secure token may include designations of the resources the user is authorized to access and may also include other data, such as a time-out window. Further, the secure token may be obfuscated (e.g., made obscure or unclear), or may be encrypted. The user is redirected from the first domain to the second domain, and the second domain places the secure token in a cookie with the user or the secure token could be a session cookie. The second domain may use the secure token to maintain the user's session with the first domain on behalf of the user, and to provide access to resources requested by the user. The user perceives a single session which is being managed across different domains and the user also perceives an uninterrupted session with the second domain. As such, the user may be unaware that the user's session with the first domain is concurrently maintained by the second domain, or of the location of resources requested. The method of the invention facilitates the maintenance of a session between a user and at least two domains, such that a user may navigate among such domains without being required to log-on each time a domain is visited. Such session maintenance is accomplished without disclosing the contents of the tokens and cookies used to achieve that functionality, i.e., the method of the invention is not dependent on the second domain's capability to read the contents of the tokens and cookies used to maintain user sessions between the user, a first domain, and at least one second domain. The invention also allows a first domain to share selected resources with another domain without the necessity of storing such resources on a web server that the first domain does not control, and to control access to resources according to whether such resources are secure or non-secure. BRIEF DESCRIPTION OF DRAWINGS The accompanying drawings, wherein like reference numerals represent like elements, are incorporated in and constitute a part of this specification and, together with the description, explain the advantages and principles of the invention. In the drawings, FIG. 1 is a block diagram of an exemplary system for maintaining multiple sessions over a network among a user, a first domain and a second domain; FIG. 2 is a block diagram of exemplary components of a computer and a server; FIG. 3A is a block diagram of an exemplary system for setting a user token; FIG. 3B is a block diagram of an exemplary system for setting a secure token; FIG. 3C is a block diagram of an exemplary system for using a secure token; FIG. 4 is a flow diagram of an exemplary method for using the secure token to maintain concurrent sessions over a network among a user, a first domain and a second domain; and FIG. 5 is a flow diagram of an exemplary method for setting the secure token. DETAILED DESCRIPTION Overview: The detailed description of embodiments of the invention herein makes reference to the accompanying drawings and figures, which show the embodiments by way of illustration and its best mode. Such embodiments are exemplary of numerous embodiments that may be made of the method of the invention. While these embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be realized and that logical and mechanical changes may be made without departing from the spirit and scope of the invention. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not limited to the order presented. The Internet is large network of computers and other devices that can communicate across a transmission medium. The computers and other devices may themselves be part of subnetworks. The documents, resources and other content available over the Internet are referred to as the World Wide Web. Web servers may store and disseminate such content in the form of web pages. A web page may represent text, graphics, animations, video, an executable file or other resources or content. Web servers and web pages are accessed by a user or client with agent software referred to as a “browser.” Examples of browsers for use with personal computers include Netscape Navigator®, Internet Explorer®, Opera® and Mozilla®. The term “webpage” as it is used herein is not meant to limit the type of documents and applications that might be used to interact with the user. For example, a typical website might include, in addition to standard HTML documents, various forms, Java applets, Javascript, active server pages (ASP), common gateway interface scripts (CGI), extensible markup language (XML), dynamic HTML, cascading style sheets (CSS), helper applications, plug-ins, and the like. A web server may include a web service which receives a request from a web server, the request including a URL (http://yahoo.com/stockquotes/ge) and an IP address (123.56.789). The web service server retrieves the appropriate web pages and serves data and applications for web pages to the IP address. Each computer or other device on a network has an address or identifier for purposes of routing or addressing messages or data packets known as an IP address. All resources and content on the World Wide Web have a Uniform Resource Identifier or URI. The Uniform Resource Locator or URL is a type of URI, and is the global address of resources and content on the World Wide Web. The URL identifies the IP address where a particular resource or content is located and the means or protocol that must be used to access the resource or content, such as HTTP or FTP. Since IP addresses are stated in numbers, for ease of reference, one or more IP addresses may be identified by an alphanumeric domain name. Web sites are locations on the World Wide Web, and typically include a collection of linked or interconnected web pages. The rules and conventions which govern the assignment of IP address, URI's, URL's, and domain names are well known in the art. The computers and other devices on the Internet exchange messages or communicate using a protocol. Protocols govern logical addressing, routing, name service, error control, flow control, and application support. The protocol for Internet communications in general use today is TCP/IP, which is an acronym for Transmission Control Protocol and Internet Protocol. TCP governs how two computers on a network establish a connection and exchange packets of data. IP governs how the data is segmented into packets. Another protocol sometimes used is UDP or User Datagram Protocol. The principal protocol used by the World Wide Web is HTTP or HyperText Transfer Protocol. HTTP establishes rules for communication between two computers on the Internet, defining how messages are formatted and transmitted, and what actions clients and servers may initiate and how they may respond. It is typically based on a client-server architecture and a request-response paradigm. That is, one computer, referred to as the client, opens communication with another computer, referred to as the host, by sending a request, to which the other computer, referred to as the server, replies by sending a response. Both the format and content of the request and the response must conform to the HTTP protocol. For example, entering a URI in a browser sends an HTTP <<GET>> request to the server for the web page located at the URI. If the URI is valid and the request is not unauthorized, the server transmits the requested web page. Additional information is contained in HTTP request-response messages and headers. For example, the message headers typically identify the URL from which the message originates, the type, version, and capabilities of the browser being used and the date, size, and type of data being sent. Additional headers may specify caching directives, the expiration or maximum age of the message, and other parameters. Each request-response pair is complete and independent of every other request-response pair. After responding to the client request, the server terminates the connection with the client. For that reason, HTTP is called a “connectionless” protocol. Moreover, the server does not track prior connections or maintain a record of the “state” or the status or condition of each connection, so each new request is received and processed without the context of such communications. For this reason, HTTP is said not to maintain state, and HTTP sessions are called “stateless.” To get around the problem of maintaining an active connection or session using a protocol that is stateless, information about the connection and messages exchanged may be included in a file stored by the client, sometimes called a cookie. A cookie may be persistent, which comprises a cookie stored on the user system which is retained notwithstanding the user exiting the browser or restarting the user system. Another type of cookie, called a session cookie, comprises a temporary record of settings and preferences relating to the navigation of a web site by a user, which cookie is deleted when the user exits the browser. The state information contained in a session cookie is returned to the web server in the next request, and the web server can send a response taking that state information into account. To the user, the session appears to be continuously active, and is sometimes called “stateful,” and session cookies are a means of managing session state. Cookies generally are specific to the domain of the server which sent the data to the client, and the contents of cookies are typically not available to servers outside the domain of the server setting the cookie. Cookie content may include user identification and password information, user preferences, browsing history, transaction history associated with the user, and the range of URL's to which the cookie is accessible. Cookies and their contents may be in clear text, or encrypted or obfuscated in whole or in part. Any method of encryption or obfuscation may be employed. For example, DES, triple-DES and public-private key systems are commonly used encryption means. Cookies may be temporary, meaning they are deleted when the browsing session ends, or persistent, meaning they are stored on the user system and not deleted when a browsing session ends. The request to store information in a cookie on the client, the content and format of that information, and the manner and extent to which such information is used by the user agent or browser and included in an HTTP request header, is generally governed by established conventions or rules. Those most applicable to HTTP sessions and to cookies are published by the IETF as Requests for Comment Nos. 2616 (“Hypertext Transfer Protocol HTTP/1.1”) and 2965 (“HTTP State Management Mechanism”). The referenced texts are hereby incorporated by reference. The exchange of confidential, proprietary or “secure” content between a client and a server may be accomplished using various security protocols. A security protocol encrypts and decrypts messages transmitted over a network, and may provide authentication of authorized recipients. Common security protocols used for Internet communications include Secure Sockets Layer or SSL, Secure HTTP or SHTTP, Private Communications Technology or PCT, IP Security or Ipsec, and Transport Layer Security or TLS. SSL is in common use and is invoked by the “https” preface in a domain name or URL. SSL provides data encryption using private key encryption technology. Where a client engages in a secure session with a server, headers in the request-response messages exchanged may specify a secure protocol, and convey state information, such as the identity of the client and the authorizations or permissions applicable to the client, i.e., what secure content may be sent in a response to a client request. For a basic introduction of cryptography and network security, the following may be helpful references: (1) “Applied Cryptography: Protocols, Algorithms, And Source Code In C,” by Bruce Schneier, published by John Wiley & Sons (second edition, 1996); (2) “Java Cryptography” by Jonathan Knudson, published by O'Reilly & Associates (1998); (3) “Cryptography & Network Security: Principles & Practice” by William Stalling, published by Prentice Hall; all of which are hereby incorporated by reference. Embodiments consistent with the invention are capable of maintaining a concurrent session between a user system and a first domain (e.g., web server), which session may be secure or non-secure, while the user is in a session with at least one second domain, which session may also be secure or non-secure, wherein resources requested by the user system, access to which includes authorization by the first domain, may be provided to the user system without requiring the user to log-on with both the first domain and the second domain, whether or not the resources are hosted at the first domain or the second domain. Typically, if there is a session to be managed, the first domain session is secure since there most likely was some type of login. In other words, if the first domain is not secure, then there really may not be a session to be maintained between the domains. Logically, it still appears there is one site, but the two domains may not be communicating as set forth herein. As such, if the user makes a request for some protected resource from the first domain, then the first domain will demand a login first. Maintaining a concurrent session is accomplished by using a secure token, which secure token is set by the first domain in the header of a response to a redirect of the user from the second domain to the first domain. The secure token is extracted from the response header, and placed by the second domain in a cookie (e.g., session cookie) with the user system. The secure token is attached to subsequent user requests made to the second first domain from the second domain. The secure token is used by the second domain to maintain an active user session with the first domain and to display the resource requested, using first domain web services that have been made available to the second domain. As one of ordinary skill will recognize, the term “display” includes access to any type of resource, including data and applications. In an embodiment, the first domain encrypts the user token set when the user logs in with the first domain, and places the encrypted user token as the secure token in the response header redirecting the user to the second domain. When the secure token is used by the second domain to maintain an active user session with the first domain, or in a request for a resource, where access to such resource includes authorization by the first domain, the first domain decrypts and may then authenticate the secure token as the user token previously set by the first domain, and thereby confirm user authorizations or permissions to access the resource requested. When making the session anonymous, in one embodiment, the second domain nulls out the secure token that is present. In an exemplary embodiment, the user token may not be encrypted and used as the secure token, but the secure token may be derived from the user token or established by some other means and associated or linked with the user token. The second domain may then further obfuscate the secure token. In one embodiment, log-on, authentication and authorization are managed by processes or services available to the first domain, also known as components or modules, as is the creation of the user token, its encryption and placement as the secure token, and its inclusion in the response header. The creation, populating and management of headers and cookies and the content of headers and cookies is also managed by services called by each of the first domain and second domain. The further obfuscation of the secure token and its use in cookies and headers is managed by the second domain. The maintenance of a user session with and access to resources hosted at the first domain is facilitated by providing the second domain with the capability of exchanging messages or calls with certain web services at the first domain. For example, the second domain might communicate a request to the first domain web service providing the functionality of validating user requests for resources. Web services are applications which are capable of interacting with other applications over a communications means, such as the Internet. Web services are typically based on standards or protocols such as XML, SOAP, WSDL and UDDI. Web services methods are well known in the art, and are covered in many standard texts. See, e.g., Alex Nghiem, “IT Web Services: A Roadmap for the Enterprise” (2003), hereby incorporated herein by reference. Exemplary embodiments of the invention include facilitating the merger of the functionality of an on-line store spanning multiple merchant web sites using a pre-paid or on-line wallet service, or providing a means to combine resources from multiple airline, auto rental, hotel and other services web sites to produce a consolidated itinerary, or allowing for the redemption of points awarded in various merchant loyalty programs such as those offered by credit card companies, at third party web sites other than the web site of the merchant maintaining the point balance. Exemplary embodiments of the invention also include a system for maintaining concurrent sessions over a network among a user, a first domain and at least one other domain, referred to herein as the second domain. Communication between the user system, first domain, and/or second domain may be accomplished through any suitable communication means, such as, for example, a telephone network, intranet, Internet, point of interaction device (point of sale device, personal digital assistant, cellular phone, kiosk, etc.), online communications, off-line communications, wireless communications, transponder communications and/or the like. One skilled in the art will also appreciate that, for security reasons, any databases, systems, or components of the present invention may include any combination of databases or components at a single location or at multiple locations, wherein each database or system includes any of various suitable security features, such as firewalls, access codes, encryption, de-encryption, compression, decompression, and/or the like. The computers discussed herein may provide a suitable website or other Internet-based graphical user interface which is accessible by users. In one embodiment, the Internet Information Server, Microsoft Transaction Server, and Microsoft SQL Server, are used in conjunction with the Microsoft operating system, Microsoft NT web server software, a Microsoft SQL database system, and a Microsoft Commerce Server. Additionally, components such as Access or SQL Server, Oracle, Sybase, Informix MySQL, Interbase, etc., may be used to provide an ADO-compliant database management system. In the embodiment shown in FIG. 1, the system 10 includes a user 12, comprised of at least a user system 14 and a user agent 16, a first domain 18, a second domain 24, and resources 20 hosted at the first domain 18. The user system 14 and the second domain 24 are connected by means of the user agent 16 and a network 22. The user system 14 and the first domain 18 are also connected by means of the user agent 16 and a network 22. The second domain 24 and the first domain 18 are connected by a network 22. For the sake of brevity, conventional data networking, application development and other functional aspects of the systems (and components of the individual operating components of the systems) may not be described in detail herein. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. The user system 14 may be any software, hardware, person, entity, and/or electronic agent for a natural person or a business entity. The user system 14 establishes a connection over a network 22 with the second domain 24 and the first domain 18 by means of the user agent 16. The user agent 16 may be any hardware and/or software configured for communicating over a network 22, including a computer and a personal digital assistant, and a network connection. The user agent 16 can be in a home or business environment. In one embodiment, access to the network 22 is via the Internet through a commercially-available web-browser software package. The user system 14 may interface with the user agent 16 by various means. The user system 14 and the user agent 16 may be collectively referred to as a user or client. In use, the relationship between the user and the second domain 24 or the first domain 18 is called a session. Upon establishing a session between the user system 14 and the second domain 24 or first domain 18, the user is in communication with the web server for such domain via a network 22. The network can include any wireline or wireless network for data transmission such as, for example, a TCP/IP network. While the system 10 will be described herein with respect to an Internet connection and the protocols associated therewith, one skilled in the art will appreciate that any network connection or protocol now known or hereafter developed may also be used in the present invention. The system 10 may be suitably coupled to network 22 via data links. A variety of conventional communications media and protocols may be used for data links. Such as, for example, a connection to an Internet Service Provider (ISP) over the local loop as is typically used in connection with standard modem communication, cable modem, Dish networks, ISDN, Digital Subscriber Line (DSL), or various wireless communication methods. Merchant system might also reside within a local area network (LAN) which interfaces to network via a leased line (T1, D3, etc.). Such communication methods are well known in the art, and are covered in a variety of standard texts. See, e.g., Gilbert Held, “Understanding Data Communications” (1996), hereby incorporated by reference. System 10 also includes a second domain 24 and a first domain 18. Each domain includes at least one web server and may include multiple interconnected computing systems sharing a common domain name, and a particular request in a session with the user may be routed to any available computing system comprising the domain. The computing systems may include a processor for processing digital data, a memory coupled to said processor for storing digital data, an input device coupled to the processor 42 for inputting data, an application program stored in said memory and accessible by said processor for directing processing of data by said processor, a display coupled to the processor and memory for displaying information derived from data processed by said processor and a plurality of databases, said databases including client data, merchant data, financial institution data and/or like data that could be used in association with the present invention. As those skilled in the art will appreciate, the computer will typically include an operating system (e.g., Windows NT, 95/98/2000, Linux, Solaris, etc.), and various application and support software and drivers typically associated with computers. Such application and support software may include components that provide discrete functionality and have well-defined interfaces. For example, such components might retain information concerning the state of a user session, or provide authentication and authorization services, or display requested resources following valid authentication and authorization. In an embodiment as described herein, the second domain serves as the host or primary connection with the user. Whether the user established the session with the second domain directly, by a hyperlink from another domain or by some other means is not material to the invention. Typically, the user establishes a session with the second domain to transact business or to obtain information or services. For example, the second domain may be an on-line store, and the user connects to the second domain for purposes of searching and possibly purchasing goods or services. System also includes a first domain. The first domain controls access to resources, which may be stored at the first domain, or the first domain may serve as a conduit or gateway to a repository where such content is stored. For example, the first domain may provide access to credit information personal to the user, or to the balance of a pre-paid account which may be used to make purchases, or to the balance of points or tokens that may be redeemed for goods or services. Resources may include text, graphics, animations, video, an executable file and/or any other data, content or resource. Resources so hosted may or may not be stored at the first domain, but may be stored at other locations and accessed through the first domain by a network or other means. In addition, content may be secure, e.g., accessible only by authorized persons in secure sessions, or non-secure, e.g., accessible by anyone in non-secure sessions. An example of a secure resource might include the balance of a user's credit card account, or a transaction history for such account. An example of a non-secure resource may be a list or other presentation of goods for purchase, as might be displayed at the website of an online merchant. One skilled in the art will also appreciate that any databases, systems, or components of the present invention may include any combination of databases or components at a single location or at multiple locations, wherein each database or system includes any of various suitable security features, such as firewalls, access codes, encryption, de-encryption, compression, decompression, and/or the like. Any databases discussed herein may be any type of database, such as relational, hierarchical, object-oriented, and/or the like. Common database products that may be used to implement the databases include DB2 by IBM (White Plains, N.Y.), any of the database products available from Oracle Corporation (Redwood Shores, Calif.), Microsoft Access or MSSQL by Microsoft Corporation (Redmond, Wash.), or any other database product. Database may be organized in any suitable manner, including as data tables or lookup tables. Association of certain data may be accomplished through any data association technique known and practiced in the art. For example, the association may be accomplished either manually or automatically. Automatic association techniques may include, for example, a database search, a database merge, GREP, AGREP, SQL, and/or the like. The association step may be accomplished by a database merge function, for example, using a “key field”in each of the manufacturer and retailer data tables. A “key field” partitions the database according to the high-level class of objects defined by the key field. For example, a certain class may be designated as a key field in both the first data table and the second data table, and the two data tables may then be merged on the basis of the class data in the key field. In this embodiment, the data corresponding to the key field in each of the merged data tables is preferably the same. However, data tables having similar, though not identical, data in the key fields may also be merged by using AGREP, for example. The first domain and the second domain interactively connected at least in that the second domain may access certain services and resources hosted at the first domain using previously established interfaces and protocols. One skilled in the art will recognize that such interfaces and protocols may take many forms, and may include something as basic as web services or an HTML based form populated by the second server that is accessed via the Internet, or a proprietary scripting language. FIG. 2 is a block diagram of an exemplary computer 30 illustrating typical components of a user system 24 or a web server or other computer that is a component of the first domain 18 or the second domain 24. Computer 30 can include a connection with a network 22 such as, for example, the Internet through any suitable network connection. Computer 30 typically includes a memory 32, a secondary storage device 40, a processor 42, an input device 36 for entering information into computer 30, a display device 38 for providing a visual display of information, and an output device 44 for outputting information such as in hard copy or audio form. Memory 32 may include random access memory (RAM) or similar types of memory, and it may store one or more applications 34 for execution by processor 42. Secondary storage device 40 may include a hard disk drive, floppy disk drive, CD-ROM drive, or other types of non-volatile data storage. Processor 42 may execute applications or programs stored in memory 34 or secondary storage 40, or received from the Internet or other network 16. Although computer 30 is depicted with various components, one skilled in the art will appreciate that the server and agent computers can contain different components. As described herein, the computing units may be connected with each other via a data communication network. The network may be a public network and assumed to be insecure and open to eavesdroppers. In the illustrated implementation, the network may be embodied as the Internet. In this context, the computers may or may not be connected to the Internet at all times. For instance, the user may employ a computer and modem to occasionally connect to the Internet, whereas the web server computers might maintain a permanent connection to the Internet. Specific information related to the protocols, standards, and application software utilized in connection with the Internet may not be discussed herein. For further information regarding such details, see, for example, Dilip Naik, “Internet Standards and Protocols” (1998); “Java 2 Complete”, various authors, (Sybex 1999); Deborah Ray and Eric Ray, “Mastering HTML 4.0” (1997); Loshin, “TCP/IP Clearly Explained” (1997); and David Gourley and Brian Totty, “HTTP, The Definitive Guide” (2002). All of these texts are hereby incorporated by reference. The systems may be suitably coupled to a network via data links. A variety of conventional communications media and protocols may be used for data links. Such as, for example, a connection to an Internet Service Provider (ISP) over the local loop as is typically used in connection with standard modem communication, cable modem, Dish networks, ISDN, Digital Subscriber Line (DSL), or various wireless communication methods. Any of the computers might also reside within a local area network (LAN) which interfaces to network via a leased line (T1, D3, etc.). Such communication methods are well known in the art, and are covered in a variety of standard texts. See, e.g., Gilbert Held, “Understanding Data Communications” (1996), hereby incorporated by reference. Embodiments of invention may be described herein in terms of functional block components, optional selections and various processing steps. It should be appreciated that such functional blocks may be realized by any number of hardware and/or software components configured to perform the specified functions. For example, embodiments of the invention may employ various integrated circuit components, e.g., memory elements, processing elements, logic elements, look-up tables, and the like, which may carry out a variety of functions under the control of one or more microprocessors or other control devices. Similarly, the software elements of the present invention may be implemented with any programming or scripting language such as C, C++, Java, COBOL, assembler, PERL, Visual Basic, SQL Stored Procedures, extensible markup language (XML), with the various algorithms being implemented with any combination of data structures, objects, processes, routines or other programming elements. Further, it should be noted that embodiments of the invention may employ any number of conventional techniques for data transmission, signaling, data processing, network control, and the like. Many applications of embodiments of the invention could be formulated. One skilled in the art will appreciate that the network may include any system for exchanging data or transacting business, such as the Internet, an intranet, an extranet, WAN, LAN, satellite communications, and/or the like. It is noted that the network may be implemented as other types of networks, such as an interactive television (ITV) network. The users may interact with the system via any input device such as a keyboard, mouse, kiosk, personal digital assistant, handheld computer (e.g., Palm Pilot®), cellular phone and/or the like. Similarly, the invention could be used in conjunction with any type of personal computer, network computer, workstation, minicomputer, mainframe, or the like running any operating system such as any version of Windows, Windows NT, Windows2000, Windows 98, Windows 95, MacOS, OS/2, BeOS, Linux, UNIX, Solaris or the like. Moreover, although embodiments of the invention are frequently described herein as being implemented with TCP/IP communications protocols, it will be readily understood that such embodiments could also be implemented using IPX, Appletalk, IP6, NetBIOS, OSI or any number of existing or future protocols. FIG. 3A is a block diagram of an exemplary system 10 by which a user logs on to the first domain 18. A session is established via the network between the user system 14 and the first domain 18. The user log-on to the first domain 18 is managed by a login service 24. The login service 24 may include more than one application residing on one or more web servers or computers in the first domain 18. The login service 24 authenticates or verifies the identity of the user and returns a user token or tag in the response header disclosing the state of the user session with the first domain as logged-in. The user token or tag is preserved by the user agent 16 as a cookie. Additional information concerning the user, such as the nature or types of resources that the user is authorized or permitted to access, may also be disclosed in a similar fashion. However, in certain embodiments, user information is not available to the second domain; rather, the second domain receives the secure token and the second domain uses the secure token as a key to facilitate access to information, while having minimal or no access or information related to the resources within the first domain. FIG. 3B is a block diagram of an exemplary system by which a secure token is set. A session is established via the network 22 between the user and the second domain 24. The user initiates a request at the second domain 24. For purposes of FIG. 3B, the user has logged on to the first domain 18 prior to such request. The user token is included in the user request header by the user agent 16. The user request is redirected to the first domain 18 for purposes of authentication. In the embodiment illustrated, the first domain 18 authenticates the user by validating the user token which was set on the user system at the time of the prior user log-on. The authentication process is managed by a security service 26. The security service 26 may include at least one application residing on one or more web servers or computers in the first domain 18. The security service 26 confirms that the state of the user session is logged-on to the first domain 18. The security service 26 may comprise further logic that causes the expiration of the logged-on status if, for example, the elapsed time between the initial log-on by the user and the request to authenticate the logged-on status of the user exceeds a predetermined value. For purposes of FIG. 3B, the user has logged-on and such logged-on status is valid. The security service 26 encrypts the user/session credential to create a secure token, then returns a secure token or tag in the response header disclosing the state of the user session with the first domain 18 as logged-on. The secure token is included in a response header sent by the first domain 24 to the user system 14, and is set by the second domain in a cookie on the user system. Additional information concerning the user, such as the nature or types of resources that the user is authorized or permitted to access, may also be disclosed in a similar fashion. The presence of the secure token in the cookie set by the second domain defines a session and the session identifies the user and establishes the resources which the user is authorized to access, and which the second domain is authorized to display to the user. FIG. 3C is a block diagram of an exemplary system by which a secure token is used to retrieve user information from the first domain 18 fromby the second domain 24. As the user browses the second domain 24, the user system 14 initiates multiple requests directed to the second domain. The requests include information set by the second domain 24 and stored as cookies by the user agent 16 in response to a <<SET COOKIE>> command initiated by the second domain 24, such as the secure token. When the second domain 24 receives such requests, it uses the secure token returned in the user request in a communication with the security service 26 component of the first domain 18. The communication may be a request to maintain the state of the user session with the first domain 18 as logged-on or active, or to display resources requested by the user system 14. The security service 26 at least authenticates the second server 16 as an authorized origin for such communication, verifies and authenticates the secure token present in the communication, and updates the state of the user session, authorizes the data to be acquired by the second domain and displayed again by the second domain, or both, depending on the validity of the communication and secure token. With reference to FIGS. 1 and 4, the invention includes an exemplary method for using the secure token to maintain concurrent sessions over a network 22 among a user, a first domain 18 and a second domain 24. The method can be implemented in, for example, hardware and/or software modules for execution by a computer. In one embodiment, a user, in a session with the second domain 24, requests a resource. (Step 1) The user may establish the session with the second domain 24 by any means, including directly requesting the connection to the second domain 24 by entering its URL in a browser, or indirectly by referral or hyperlink from another URL. The user session may be one of secure or non-secure, which in the embodiment illustrated in FIG. 4 is, for example, HTTPS or HTTP, respectively. The user request is transmitted by the user agent 16 to the second domain 24 via a network. As indicated above, this request can originate from a variety of computers or other devices via any communications network. The user agent 16 prepares and formats the user request according to the protocol established for communicating with the second domain 24, which is one of non-secure or secure. The user request header created by the user agent 16 typically identifies whether the session is conducted using a non-secure protocol, such as HTTP, and is therefore a non-secure session, or whether the session is conducted using a secure protocol, such as HTTPS, and is therefore a secure session. Data from cookies, such as tokens or tags, may also be included by the user agent 16 in the user request header. The user request is received by the second domain and processed 54, and, depending on the presence and value of a secure token in the user requestuser's response header, the second domain takes certain actions respecting the user request, such as maintaining the state of the user session with the second domain as logged-on or active, obtaining the resource requested by the user, or directing the user to log in with the first domain. (Step 2) In the embodiment illustrated, the second domain checks for the presence and value of the secure token 54. In one embodiment, during the user's initial request to the second domain, the second domain also determines from the user request header whether the user session is non-secure or secure 66; however, the type of session may be determined at other points in the process. If the secure token is not present in the cookie set by the second domain, the user system is redirected to the second first domain for authentication or log-on 56. (Step 3) If the secure token is present in the user cookie and has no value (i.e., no value) 58, and the user request is for a non-secure resource that may be displayed in a non-secure (e.g., HTTP) session 60, the resource requested will be displayed to the user 76. If the secure token is present in the user cookie and has no value 58, and the user request is for a secure resource that may be displayed only in a secure (e.g., HTTPS) session 60, the user will be redirected to first domain 56 to log-in. (Step 3) If the secure token is present in the user cookie and has a value 58, then the second domain will substantially determine when the secure token was last used to refresh, keep alive or maintain the session state between the user and the first domain as logged-on or active 64. In one embodiment, this may be accomplished by a request to maintain the session as logged-on or active 70, herein called a “keep alive” web service request, in which the secure token is included, made by the second domain to the first domain. (Step 9). The second domain will clarify the obfuscated security token If the secure token has been obfuscated by the second domain, the second domain will clarify the secure token and include it in the keep-alive request 70 (de-obfuscating the secure token may also applicable in other embodiments and steps, such as, for example, acquiring a secure resource). The keep-alive request is processed by an application service at the first domain, which, among other steps, substantially determines whether the keep-alive request originated from a domain authorized to make such requests and whether the secure token included in the request is valid 72. In addition to a keep alive request, in one embodiment, the system may include a secure token which fulfills the user request by displaying the requested resource 74. The present invention may include two methods for managing the session between the domains. As an initial matter, active requests for resources from the second domain to the first domain reset the session period. In one embodiment for managing the session timer, as described, an application timer is used to determine when an explicit request to reset the session timer is made from the second domain. In another embodiment, an explicit request is made for every page requested by the user from the second domain. In other words, instead of using a timer to know when to reset the session, a reset is simply made for every page for the user session. This embodiment may be seamless because it is the method for managing the session on the first domain. The frequency of keep-alive requests may be mitigated by employing the following additional steps separately or in combination 64. For example, where the time elapsed since the last such use exceeds a pre-set value, the user session with the first domain will be deemed to have expired and the user will be directed to the first domain to log-on and establish another session 56. If the time elapsed since the last such use does not exceed the preset value, the second domain will make a keep-alive request to the first domain and include the secure token in such request 70, and fulfill the user request 74 by displaying the resource requested 76. Optionally, as a means to balance keep-alive requests, the second domain may make such requests only where the elapsed time since the last such request is within a predefined window. For example, where the elapsed time is greater than some minimum below which the likelihood of the session between the user and the first domain having expired is low, the second domain may omit the step of using the secure token to refresh, keep-alive or maintain an active user session, and use the secure token to fulfill the user request by displaying the requested resource. If the secure token used by the second domain in a keep-alive request or in displaying the requested resource is not accepted by the first domain security service, the user is re-directed to the first domain to log-on, if the resource being requested is secure (e.g., HTTPS). The exemplary logic of the second domain in processing the user request may be represented in tabular form as a function of the presence or absence of the secure token, the value of the secure token if present, the type of session requested, i.e., secure or non-secure, and the time elapsed since the last call to the security web service to maintain an active user session with the first domain. When making the session anonymous with a non-secure resource, in one embodiment, the second domain nulls out the secure token that is present. Moreover, to trigger the refresh, the invention establishes a discrete session maximum and a refresh minimum threshold. Secure Last Token Value HTTP/S Use Action Not — — Redirect to first domain present Present No HTTP — Display resource value Present No HTTPS — Redirect to first domain value Present ≠No HTTP >10 Display Resource, make session value min. anonymous Present ≠No HTTPS >10 Redirect to first domain value min. Present ≠No — <10 Maximum session time value min. >8 Refresh session minimum, display min. resource Present ≠No — ≦8 Display resource value min. FIG. 5 is a flow diagram of an exemplary method for setting the secure token. The secure token is set by the first domain following redirect by the second domain of a user request for a resource controlled by or accessed through the first second domain 56. (Step 3) The secure token is then placed in the response header to the redirect of the user request from the second domain back to the first domain. (Step 7) In an exemplary method, upon redirect of the user request 56, the first domain first substantially determines whether the user has already logged-on to the first domain 100. This is accomplished by checking for the presence of the user token set by the first domain at user logon 102 and authenticating the user token if present 114. (Step 4) The authenticating step is managed by an application service. If the user token is not present, or if the user token is present but is not valid, and the user request is for a non-secure resource 104, the secure token is created and its value is set at no value 110. (Step 4) The no value secure token is included in the response header to the redirect of the user request from the second domain 112. If the user token is not present or if the user token is present but is not valid, and the user request is for a secure resource, the user is directed to log-on at the first domain 106. The log-on is managed by an application service. Upon successful log-on 108, the first domain sets a user token in a cookie 110, and the user restarts the authentication step 100. If the user token is present, then the first domain will attempt to authenticate the user token using the security service 114. (Step 5) The security service may, among other steps, compare the user token present with the user token that was set by the first domain on user log-on. If the user token is present and is authenticated by the first domain, the first domain will set a secure token in the response header to the redirect of the user request from the second domain. In the exemplary embodiment, the user token is encrypted and set as the value of the secure token 118. (Step 7) Use of an encrypted value for the secure token may provide some protection against a compromise of session security, for example, by spoofing the first domain header information. The actions taken by the first domain in setting the secure token can be represented in a table as a function of the presence and validity of a user token, and the type of resource requested, i.e., non-secure or secure (HTTP or HTTPS, respectively). User Token Valid HTTP/S Action Not — HTTP Secure token value set to no value present Not — HTTPS User directed to log-on; Encrypted user present token set as secure token value Present No HTTP Secure token value set to no value Present No HTTPS User directed to log-on; Encrypted user token set as secure token value Present Yes — Encrypted user token set as secure token value The second domain receives the response from the first web domain to the redirect of the user request from the second domain 120, parses the response header, and uses the secure token included therein as the secure token value to be set in a secure (e.g., HTTPS) cookie and obfuscates the secure token and places that value in a non-secure (e.g., HTTP) cookie with the user agent for use when resources from the first domain are needed. (Step 8) In one embodiment, the system may trigger the second domain when to refresh itself against the first domain (e.g., to avoid an arbitrary refresh) when it knows that there have been changes of interest for the second domain. In requests from the user to the second domain, the user agent will include the secure token contained in the session cookie set by the second domain in the request header. In another exemplary embodiment, instead of or in addition to the second domain checking whether it has a secure token, the second domain may check (e.g., each time) the first domain for an active token. As such, if an event occurred since the time when the second domain acquired the secure token, the next time any action occurs on the second domain, the new event is available to the second domain. While the methods disclosed herein have been described and shown with reference to particular steps performed in a particular order, it will be understood that these steps may be combined, sub-divided, or re-ordered to form an equivalent method without departing from the teachings of the present invention. Accordingly, unless specifically indicated herein, the order and grouping of the steps is not a limitation of the present invention.

<SOH> BACKGROUND OF INVENTION <EOH>It is increasingly common for transactions and services to be provided by electronic means. The conduct of such business to business and business to consumer transactions and the delivery of services is often facilitated by a user connecting to a host or server on the World Wide Web. In providing transactions and services to the user or client, the host may need to marshal resources, including applications and data, hosted at related servers or on third party servers. For example, an on-line store may offer a user the opportunity to browse and purchase products offered by multiple vendors. The store may need to display products and prices derived from such vendors' servers, process a purchase or sale transaction, and provide for payment and shipping. In accessing such resources, a connection is typically established with, or request made to, the server hosting the requested resource. Where the resource is partially or fully secure, it may be available only following log-on by the user and the establishment of a secure session with the server where the secure application or data resides. The log-on may provide authentication of the user and verification of the authorization of the user to access the requested resource. Log-on may be effected by supplying a user name and password which matches a user name and password previously established with the server hosting the resource, and sometimes additionally by the successful completion of a challenge query and a proper response sequence. The requirement of sign-in, authentication, and authorization in order to obtain secure content may interrupt the perceived continuity of the session established between the user and the host. The user may be requested to engage in the authentication and authorization process multiple times, such as by logging-on, with the host and third party servers, in order to access applications and data. Each log-on may include a different user name or identification and password. The interruption of the session with the host, and the possible need to retain multiple user names and passwords, detracts from the user experience. Moreover, the session with one server may expire or time-out, thereby requiring the user to log-on again. Methods exist to avoid multiple authentication and authorization steps by the user, while merging the functionality and resources of more than one site. Some such methods are referred to as “single sign-on” or SSO. Such methods generally include the use of a central authentication service which stores user identities and authorizations for various servers. The user typically logs-on once with the service, and may then access the applications and data for which authorization has been supplied by the service. The service may host the user session by providing a single log-on and negotiating for access to secure data with other web servers participating in the service. This solution to multiple user log-on is often complicated and expensive to deploy and maintain. An example of single-sign-in methodology is Microsoft Corporation's Passport® single sign-in protocol, which provides users a means to sign-in to participating merchant web sites by signing-in and being authenticated only once to a common server. The Passport® protocol relies upon encrypted cookies set by the Passport® server. When a user begins a session with a merchant web site, the merchant web site re-directs the user to a Passport® server. The user logs-on with the Passport® server, and the Passport® server returns encrypted authentication information which is set as a cookie with the user system. Such authentication information can only be decrypted by the merchant web site. When the user returns to the merchant web site, the encrypted cookie is also returned to the merchant web site. The cookie is decrypted at the merchant web site and the user is verified as authenticated. The Passport® server also sets a cookie by which it can recognize the user as logged-in. Thus, if the user visits a second merchant web site, on re-direct to the Passport® server the Passport® server recognizes the user as already logged-in, and does not require another log-on, but returns authentication information that can only be decrypted by the second merchant web site, and redirects the user to that web site. Current approaches to multiple authentication and authorization may include the sharing of confidential information about the user with the third party authentication service, and the necessity of updating such information on both the server owning the information and the third party server providing the authentication service. The placement of proprietary databases containing user information with a third party server also increases security risks. Accordingly, a need exists for a less complicated and more cost effective way to address the requirement of sign-in, authentication, and authorization for multiple servers.

<SOH> SUMMARY OF INVENTION <EOH>A method and apparatus facilitates the sharing of data between one domain and at least one other domain over a network, by the use of at least one token created by the first domain. The first domain and the other domain, herein referred to as the second domain, are capable of interactively communicating with each other. While in a session with the second domain, the user requests a resource, access to which is controlled or includes authorization by the first domain. The resource may be hosted at the second domain, the first domain or another domain, and which resource may be at least one of secure and non-secure. The second domain initially redirects the user request to the first domain, and the first domain authenticates the user, said authentication including at least determining whether the user has previously established a user session by logging-on with the first domain, and, if not logged-on, may requesting the user to log-on with the first domain; determining whether the user session is still valid, for instance, has not expired or timed out; and determining what resources the user is authorized or permitted to access. The process of authenticating the user includes at least verifying the presence on the user system of a user token set by the first domain at the time the user logged-in to the first domain. If the user token is present, and the first domain determines the user token to be substantially authentic and valid, for instance, not expired or timed-out, and the user request to be within the authorization of the user established at log-on, the first domain uses the user token to create a secure token and places the secure token in a header to the first domain's response to the redirect of the user. The secure token may include a form of the user token, or may be created in some other manner that allows the secure token to be associated with the authenticated user in subsequent communications. The secure token may include designations of the resources the user is authorized to access and may also include other data, such as a time-out window. Further, the secure token may be obfuscated (e.g., made obscure or unclear), or may be encrypted. The user is redirected from the first domain to the second domain, and the second domain places the secure token in a cookie with the user or the secure token could be a session cookie. The second domain may use the secure token to maintain the user's session with the first domain on behalf of the user, and to provide access to resources requested by the user. The user perceives a single session which is being managed across different domains and the user also perceives an uninterrupted session with the second domain. As such, the user may be unaware that the user's session with the first domain is concurrently maintained by the second domain, or of the location of resources requested. The method of the invention facilitates the maintenance of a session between a user and at least two domains, such that a user may navigate among such domains without being required to log-on each time a domain is visited. Such session maintenance is accomplished without disclosing the contents of the tokens and cookies used to achieve that functionality, i.e., the method of the invention is not dependent on the second domain's capability to read the contents of the tokens and cookies used to maintain user sessions between the user, a first domain, and at least one second domain. The invention also allows a first domain to share selected resources with another domain without the necessity of storing such resources on a web server that the first domain does not control, and to control access to resources according to whether such resources are secure or non-secure.

20040310

20080408

20050915

58956.0

PEESO, THOMAS R

SECURITY SESSION AUTHENTICATION SYSTEM AND METHOD

UNDISCOUNTED

ACCEPTED

ACCEPTED

SELF SEALING HEAT STAKE ON AN OVERMOLDED PANEL

An automotive door panel assembly is provided, comprising a door trim panel. The door trim panel is comprised of an outer trim panel surface; an inner trim panel surface; and at least one tubular stake. The tubular stake includes outer tubular walls protruding from the inner trim panel surface. The tubular stake including a seal sleeve flow channel connecting the outer trim panel surface to the inner trim panel surface. The panel assembly includes an overmold material applied to the outer trim panel surface. The overmold material fills the seal sleeve flow channel and generates an overmold seal sleeve skin on the outer tubular walls. A door main panel assembly is included having at least one clip hole. The tubular stake is positioned within the at least one clip hole. The overmold seal sleeve skin removably engages the at least one clip hole to form a primary seal between the door trim panel and the door main panel assembly.

1. An automotive door panel assembly comprising: a door trim panel comprising: an outer trim panel surface; an inner trim panel surface; and at least one tubular stake including outer tubular walls protruding from said inner trim panel surface, said tubular stake including a seal sleeve flow channel connecting said outer trim panel surface to said inner trim panel surface; an overmold material applied to said outer trim panel surface, said overmold material filling said seal sleeve flow channel and generating an overmold seal sleeve skin on said outer tubular walls; a door main panel assembly including at least one clip hole, said tubular stake positioned within said at least one clip hole; and wherein said overmold seal sleeve skin removably engages said at least one clip hole to form a primary seal between said door trim panel and said door main panel assembly. 2. An automotive door panel assembly as described in claim 1, wherein said overmold seal sleeve skin comprises: a chamfered guide top; and a seal sleeve wall secured to said outer tubular walls. 3. An automotive door panel assembly as described in claim 1, further comprising: an outer overmold seal formed on an edge surface of said outer trim panel surface, said outer overmold seal engaging said door main panel assembly to form a secondary sealing surface between said door trim panel and said door main panel assembly. 4. An automotive door panel assembly as described in claim 1, wherein said overmold seal sleeve skin further comprises: an engagement notch feature formed in a seal sleeve wall, said engagement notch feature engaging said at least one clip hole when said tubular stake is positioned within said at least one clip hole. 5. An automotive door panel assembly as described in claim 1, wherein said trim panel comprises: a plurality of said tubular stakes positioned around a perimeter mounting region of said door trim panel. 6. An automotive door panel assembly as described in claim 1, wherein said seal sleeve skin comprises a tubular sleeve in radial compression within said clip hole. 7. An automotive door panel assembly as described in claim 1, wherein said seal sleeve skin comprises a skin end in contact with said inner trim panel surface. 8. A weather resistant panel assembly comprising: a trim panel comprising: an outer trim panel surface; an inner trim panel surface; and at least one tubular stake including a seal sleeve flow channel connecting said outer trim panel surface to said inner trim panel surface; an overmold material applied to said outer trim panel surface, said overmold material filling said seal sleeve flow channel and generating an overmold seal sleeve skin; a main panel assembly including at least one clip hole, said overmold seal sleeve skin positioned within said at least one clip hole; and wherein said overmold seal sleeve skin removably engages said at least one clip hole to form a primary seal between said trim panel and said main panel assembly. 9. A weather resistant panel assembly as described in claim 8, wherein said overmold seal sleeve skin comprises: a chamfered guide top; and a seal sleeve wall secured to said outer tubular walls. 10. A weather resistant panel assembly as described in claim 8, further comprising: an outer overmold seal formed on an edge surface of said outer trim panel surface, said outer overmold seal engaging said main panel assembly to form a secondary sealing surface between said trim panel and said main panel assembly. 11. A weather resistant panel assembly as described in claim 8, wherein said overmold seal sleeve skin further comprises: an engagement notch feature formed in a seal sleeve wall, said engagement notch feature engaging said at least one clip hole when said tubular stake is positioned within said at least one clip hole. 12. A weather resistant panel assembly as described in claim 8, wherein said trim panel comprises: a plurality of said tubular stakes positioned around a perimeter mounting region of said trim panel. 13. A weather resistant panel assembly as described in claim 8, wherein said seal sleeve skin comprises a tubular sleeve in radial compression within said clip hole. 14. A weather resistant panel assembly as described in claim 8, wherein said seal sleeve skin comprises a skin end in contact with said inner trim panel surface. 15. A method of manufacturing a moisture resistant panel assembly comprising: forming a trim panel comprising: an outer trim panel surface; an trim panel inner surface; and a tubular stake including outer tubular walls protruding from said inner trim panel surface; said tubular stake including a seal sleeve flow channel connecting said outer trim panel surface to said inner trim panel surface; placing said trim panel in an overmolding assembly; injecting an overmold material such that; said overmold material flows onto said outer surface to form an outer overmold skin; said overmold material flows through said seal sleeve flow channel from said outer trim panel surface towards said inner trim panel surface; and said overmold material flows over said tubular stake to form an overmold sleeve skin on said outer tubular walls. 16. A method of manufacturing a moisture resistant panel assembly as described in claim 15, further comprising: installing said trim panel into a main panel assembly such that said tubular stake is positioned within at least one clip hole formed in said main panel assembly; and generating a seal between said trim panel and said main panel assembly by way of said overmold sleeve skin removably engaging said at least one clip hole. 17. A method of manufacturing a moisture resistant panel assembly as described in claim 15, further comprising: forming an engagement feature in said overmold sleeve skin such that said overmold sleeve skin lockingly engages said at least one clip hole. 18. A method of manufacturing a moisture resistant panel assembly as described in claim 15, further comprising: flowing said overmold material on said outer trim panel surface into contact with an edge surface of said outer trim panel surface to form an outer overmold seal, said outer overmold seal engaging said main panel assembly to form a secondary sealing surface between said trim panel and said main panel assembly. 19. A method of manufacturing a moisture resistant panel assembly as described in claim 18, further comprising: installing said trim panel into a main panel assembly such that said tubular stake is positioned within at least one clip hole formed in said main panel assembly; and generating a seal between said trim panel and said main panel assembly by way of said overmold sleeve skin removably engaging said at least one clip hole; generating a secondary seal between said trim panel and said main panel assembly by forcing said outer overmold seal into engagement with said main panel assembly. 20. A manufacturing a moisture resistant panel assembly as described in claim 16, wherein said overmold sleeve skin is placed in radial compression to seal said at least one clip hole.

BACKGROUND OF INVENTION The present invention relates generally to an overmolded staked panel assembly and more particularly to a flowthrough stake element allowing overmold material to flow from through the stake element to form a self sealing heat stake. Automotive components play an important role in automobile design and functionality. Components such as vehicle doors provide controls for a wide variety of electrically based functions within the automobile. In addition, comfort and styling as increased the number of modular panels utilized in assembling vehicle doors. As such, present automotive door construction has increased in complexity. The complexity is further increased by the requirement of accessibility of many of the electrical components throughout the lifecycle of the vehicle. Replacement or repair may be required during the vehicle lifecycle, which in turn often requires the modular panels to be removable. Complexity of design is intertwined with complexity of function within these assemblies. Continuous proper functioning of the vehicle door and installed components requires these components to operate after exposure of the vehicle door to weather conditions such as rain or snow. The solution has been the development of wet modular trim panels. These panels provide a water seal between all the sub components and the main door trim panel. Manufacturing and assembly of such assemblies can be time consuming and costly. Present manufacturing techniques often utilize heat stake technology wherein the use of resilient seals placed on heat stakes and subsequently heat staked into place. These panels are then used to snap-fit onto the main door trim panel. Manufacturing of such trim pieces can result in unduly complicated processes. Furthermore, the removal of such trim pieces from the main door trim panel can be difficult. It would be desirable, therefore, to have a modular trim door panel assembly with improved manufacturing and assembly characteristics. It would additionally, be highly desirable to have a modular trim door panel assembly having easily removed trim panels with improved water penetration resistance. SUMMARY OF INVENTION It is therefore an object of the present invention to provide an automotive door panel assembly with improved manufacturing and assembly characteristics. It is a further object of the present invention to provide an automotive door panel assembly with improved removability of sealed trim panels. In accordance with the objects of the present invention an automotive door panel assembly is provided. An automotive door panel assembly is provided, comprising a door trim panel. The door trim panel is comprised of an outer trim panel surface; an inner trim panel surface; and at least one tubular stake. The tubular stake includes outer tubular walls protruding from the inner trim panel surface. The tubular stake including a seal sleeve flow channel connecting the outer trim panel surface to the inner trim panel surface. The panel assembly includes an overmold material applied to the outer trim panel surface. The overmold material fills the seal sleeve flow channel and generates an overmold seal sleeve skin on the outer tubular walls. A door main panel assembly is included having at least one clip hole. The tubular stake is positioned within the at least one clip hole. The overmold seal sleeve skin removably engages the at least one clip hole to form a primary seal between the door trim panel and the door main panel assembly. Other objects and features of the present invention will become apparent when viewed in light of the detailed description and preferred embodiment when taken in conjunction with the attached drawings and claims. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an illustration of an automotive door panel assembly in accordance with the present invention. FIG. 2 is a cross-section of the automotive door panel assembly illustrated in FIG. 1, the cross-section taken along the lines 2-2 in the direction of the arrows. FIG. 3 is an illustration of a method of forming a door trim panel for use in the automotive door panel assembly illustrated in FIG. 1, the door trim panel illustrated positioned within an overmolding assembly. FIG. 4 is an illustration of the door trim panel and overmolding assembly illustrated in FIG. 3, the illustration showing the injection of overmolding material. DETAILED DESCRIPTION Referring now to FIG. 1, which is an illustration of an automotive door panel assembly 10 in accordance with the present invention. The automotive door panel assembly 10 is illustrated in a specific embodiment, however, alternate embodiments are contemplated including additional automotive trim panel components including non-door components. The automotive door panel assembly 10 includes at least one door trim panel 12. Door trim panels 12 are utilized in automotive door panel assemblies 10 and are known to come in a vast array of sizes and shapes. The door trim panel 12 proposed by the present invention provides a unique and productive structure and method for mounting the door trim panel 12 to a door main panel assembly 28. The unique door trim panel 12 includes an outer trim panel surface 14 and an inner trim panel surface 16 (see FIG. 2). Although the door trim panel 12 may be formed from a variety of materials, one embodiment contemplates the use of injection molded polymers. The door trim panel 12 includes at least one tubular stake 18 protruding from the inner trim panel surface 16. Although a single tubular stake 18 may be practical for smaller door trim panels 12, it is contemplated that the trim panel 12 may be comprised of a plurality of tubular stakes 46 positioned around a mounting perimeter region 47 of the trim panel 12. Each of the tubular stakes 18 includes outer tubular walls 20 protruding from the inner trim panel surface 16. These outer tubular walls 20 generate a seal sleeve flow channel 22 which connects the outer trim panel surface 14 to the inner trim panel surface 16. In this fashion, the door trim panel 12 can be placed within an overmolding assembly 50 as illustrated in FIG. 3. An overmold material 24, preferably a soft flexible material, can then be injected into the overmolding assembly such that the overmold material 24 is applied to the outer trim panel surface 14 (see FIG. 4). The seal sleeve flow channel 22 allows the overmold material 24 to flow from the outer trim panel surface 14 into a sleeve generating pocket 52 formed in the overmolding assembly 50 surrounding the tubular stake 46. This allows the overmold material 24 to generate an overmold seal sleeve skin 26 on the outer tubular walls 20. This methodology allows the overmolded door trim panel 12 and the overmold sleeve skin 26 to be formed using a single shot in injection molded overmold material 24. In additional, this methodology allows for the use of resilient overmolding material to form a compact, high quality seal that is bonded to the door trim panel 12. The predictable and consistent geometric form created by this processes provides substantial benefit to assembly and disassembly of the automotive door panel assembly 10. After the overmolding process has been utilized to form the overmold sleeve skin 26, the door trim panel 12 can be assembled into the door main panel assembly 28 by inserting the tubular stake 18 into a corresponding clip hole 30 formed in the main panel assembly 28. The overmold seal sleeve skin 26 thereby engages the clip hole 30 in order to form a primary seal 32 between the door trim panel 12 and the door main panel assembly 28. Although the overmold seal sleeve skin 26 can be formed in a variety of configurations, it is contemplated that it can be formed with a chamfered guide top 34 and a seal sleeve wall 36 that secures to the outer tubular walls 20. The seal sleeve skin 26 preferably comprises a skin end 48 in contact with the inner trim panel surface 16. This configuration allows for a low effort insertion into the clip hole(s) 30 while generating a tubular sleeve that is placed in radial compression within the clip hole 30 so as to generate the primary seal 32. It is further contemplated that an engagement notch 44 may be formed in the seal sleeve skin 26 during the overmolding process. The engagement notch 44 can be utilized in order to generate a resistance effort from removing the tubular stake 18 from the clip hole 30 so as to prevent unwanted separation of the trim panels or seals. It should be understood that the seal sleeve skin 26 can be formed in a variety of configurations that provide the desired qualities of improved sealing of the clip hole 30 in combination of removability of the tubular stake 18 from the clip hole 30 for maintenance or replacement. It is further contemplated that the overmold material 24 may be utilized to form an outer overmold seal 38 formed on an edge surface 40 of the outer trim panel surface 14. The outer overmold seal 38 can be utilized to engage the door main panel assembly 28 during installation such that a secondary sealing surface 42 is generated between the door trim panel 12 and the door main panel assembly 28. This provides a dual sealing system when used in conjunction with the primary seal 32 generated within the clip holes 32. This dual sealing system is further benefited by its simplicity of manufacturing and assembly by requiring only a single shot of overmolding material 24 to generate both seals. While the invention has been described in connection with one or more embodiments, it is to be understood that the specific mechanisms and techniques which have been described are merely illustrative of the principles of the invention, numerous modifications may be made to the methods and apparatus described without departing from the spirit and scope of the invention as defined by the appended claims.

<SOH> BACKGROUND OF INVENTION <EOH>The present invention relates generally to an overmolded staked panel assembly and more particularly to a flowthrough stake element allowing overmold material to flow from through the stake element to form a self sealing heat stake. Automotive components play an important role in automobile design and functionality. Components such as vehicle doors provide controls for a wide variety of electrically based functions within the automobile. In addition, comfort and styling as increased the number of modular panels utilized in assembling vehicle doors. As such, present automotive door construction has increased in complexity. The complexity is further increased by the requirement of accessibility of many of the electrical components throughout the lifecycle of the vehicle. Replacement or repair may be required during the vehicle lifecycle, which in turn often requires the modular panels to be removable. Complexity of design is intertwined with complexity of function within these assemblies. Continuous proper functioning of the vehicle door and installed components requires these components to operate after exposure of the vehicle door to weather conditions such as rain or snow. The solution has been the development of wet modular trim panels. These panels provide a water seal between all the sub components and the main door trim panel. Manufacturing and assembly of such assemblies can be time consuming and costly. Present manufacturing techniques often utilize heat stake technology wherein the use of resilient seals placed on heat stakes and subsequently heat staked into place. These panels are then used to snap-fit onto the main door trim panel. Manufacturing of such trim pieces can result in unduly complicated processes. Furthermore, the removal of such trim pieces from the main door trim panel can be difficult. It would be desirable, therefore, to have a modular trim door panel assembly with improved manufacturing and assembly characteristics. It would additionally, be highly desirable to have a modular trim door panel assembly having easily removed trim panels with improved water penetration resistance.

<SOH> SUMMARY OF INVENTION <EOH>It is therefore an object of the present invention to provide an automotive door panel assembly with improved manufacturing and assembly characteristics. It is a further object of the present invention to provide an automotive door panel assembly with improved removability of sealed trim panels. In accordance with the objects of the present invention an automotive door panel assembly is provided. An automotive door panel assembly is provided, comprising a door trim panel. The door trim panel is comprised of an outer trim panel surface; an inner trim panel surface; and at least one tubular stake. The tubular stake includes outer tubular walls protruding from the inner trim panel surface. The tubular stake including a seal sleeve flow channel connecting the outer trim panel surface to the inner trim panel surface. The panel assembly includes an overmold material applied to the outer trim panel surface. The overmold material fills the seal sleeve flow channel and generates an overmold seal sleeve skin on the outer tubular walls. A door main panel assembly is included having at least one clip hole. The tubular stake is positioned within the at least one clip hole. The overmold seal sleeve skin removably engages the at least one clip hole to form a primary seal between the door trim panel and the door main panel assembly. Other objects and features of the present invention will become apparent when viewed in light of the detailed description and preferred embodiment when taken in conjunction with the attached drawings and claims.

20040316

20051018

20050922

81016.0

MORROW, JASON S

SELF SEALING HEAT STAKE ON AN OVERMOLDED PANEL

UNDISCOUNTED

ACCEPTED

ACCEPTED

FUEL INJECTION SYSTEM

A fuel injection system for an internal combustion engine comprises a nozzle (2) with an inlet and a cam-driven plunger (5) forming a plunger chamber (7) which is connected to the inlet of the nozzle. The injection system also comprises a common rail (10) for fuel and a control valve (9) installed between the plunger chamber (7) and the common rail (10), wherein the control valve is able to open or close hydraulic communication between the plunger chamber and the common rail upon receiving an electrical control command. An electrically actuated nozzle control valve (21) is used for opening and closing of the nozzle (2). The system also comprises a means (11) for pressurizing the common rail and regulating pressure of the fuel in the common rail (10).

1. A fuel injection system for an internal combustion engine comprising a nozzle (2) with an inlet; a cam-driven plunger (5) forming a plunger chamber (7) said plunger chamber connected to the inlet of the nozzle; a common rail (10) for fuel; a control valve (9) between the plunger chamber (7) and the common rail (10), said control valve being able to open or close hydraulic communication between the plunger chamber and the common rail upon receiving an electrical control command; an electrically operated nozzle control valve (3) for opening and closing of the nozzle (2); a means (11) for pressurizing the common rail and regulating pressure of the fuel in the common rail (10); and a fuel tank (13). 2. The fuel injection system as recited in claim 1, wherein a non-return valve (20) is installed between said plunger chamber (7) and the common rail (10), with the inlet of said non-return valve connected to the common rail. 3. The fuel injection system as recited in claim 1, wherein said control valve (9) isolates said plunger chamber (7) from the common rail (10) and connects the plunger chamber (7) to the return line (12) while in a third position; isolates the plunger chamber (7) from both the return line (12) and the common rail (10) while in a second position; isolates the plunger chamber (7) from the return line (12) and connects the plunger chamber (7) to the common rail (10) while in a first position. 4. A fuel injection system comprising a nozzle (2) with an inlet and a needle (15); a resilient means (14) biasing the needle to close the nozzle; a control piston (16) forming a control chamber (17) with an input throttle (18) and an outlet port (19), said control piston abutting the needle (15) such that an higher pressure in the control chamber (17) tends to urge the control piston (16) onto the needle to close to the nozzle; a cam-driven plunger (5) forming a plunger chamber (7), said plunger chamber connected to the input throttle (18) and the inlet of the nozzle (2); a common rail (10) for fuel; a control valve (9) installed between the plunger chamber (7) and the common rail (10), said control valve (9) being able to open or close hydraulic communication between the plunger chamber and the common rail upon receiving an electrical control command; a nozzle control valve (NCV) (3) installed between the outlet port (19) of the control chamber (17) and a return line (12), said NCV being able to open or close hydraulic communication between the outlet port (17) and the return line (12); a means (11) for pressurizing the common rail and regulating pressure of the fuel in the common rail; a fuel tank (13); said fuel injection system characterized in that the effective flow areas of said input throttle (18), outlet port (19) and the NCV (3) and the force of the resilient means (14) are chosen such that an opening of the NCV can cause the needle (15) to open the nozzle when the pressure at the inlet of the nozzle is below a maximum working pressure of the common rail. 5. The fuel injection system as recited in claim 4, wherein a non-return valve (20) is installed between said plunger chamber (7) and the common rail (10), with the inlet of said non-return valve connected to the common rail. 6. The fuel injection system as recited in claim 4, wherein said control valve (9) isolates said plunger chamber (7) from the common rail (10) and connects the plunger chamber (7) to the return line (12) while in a third position; isolates the plunger chamber (7) from both the return line (12) and the common rail (10) while in a second position; isolates the plunger chamber (7) from the return line (12) and connects 15 the plunger chamber (7) to the common rail (10) while in a first position. 7. The fuel injection system as recited in claim 4, wherein said input throttle (18) is connected to the common rail (10) instead of being connected to the plunger chamber (7). 8. The fuel injection system as recited in claim 4, wherein said outlet port (19) and the control piston (16) are designed such that the control piston (16) is able to restrict the flow area of the outlet port (19) at a position corresponding to an open nozzle (2), thereby limiting the leakage of pressurized fuel through the input throttle (18), output port (19) and open NCV (3) to the return line (12). 9. A fuel injection system comprising a nozzle (2) with an inlet and a needle (15); a resilient means (14) biasing the needle (15) to close the nozzle (2); a control piston (16) forming a control chamber (17) and abutting the needle (15) such that an higher pressure in the control chamber (17) tends to urge the control piston (16) onto the needle (15) to close the nozzle (2); a cam-driven plunger (5) forming a plunger chamber (7), said plunger chamber connected to the inlet of the nozzle (2); a common rail (10) for fuel; a control valve (9) installed between the plunger chamber (7) and the common rail (10), said control valve being able to open or close hydraulic communication between the plunger chamber and the common rail upon receiving an electrical control command; a nozzle control valve (NCV) (3), said NCV being able to isolate said control chamber (17) from a return line (12) and open hydraulic communication between said plunger chamber (7) and the control chamber (17) while in a first position and being able to isolate the control chamber (17) from the plunger chamber (7) and hydraulically connect the control chamber (17) to the return line (12) while in a second position; a means for pressurizing the common rail (10) and regulating pressure of the fuel in the common rail; a fuel tank (13); said fuel injection system characterized in that the pressure in the common rail (10) can be set sufficiently high to overcome the force of the resilient means (14) and open the nozzle (2) when the NCV (3) is in its second position. 10. The fuel injection system as recited in claim 9, wherein a non-return valve (20) is installed between said plunger chamber (7) and the common rail (10), with the inlet of said non-return valve connected to the common rail. 11. The fuel injection system as recited in claim 9, wherein said control valve (9) isolates said plunger chamber (7) from the common rail (10) and connects the plunger chamber (7) to the return line (12) while in a third position; isolates the plunger chamber (7) from both the return line (12) and the common rail (10) while in a second position; isolates the plunger chamber (7) from the return line (12) and connects the plunger chamber (7) to the common rail (10) while in a first position. 12. The fuel injection system as recited in claim 9, wherein said NCV (3) isolates said control chamber (17) from the return line (12) and opens hydraulic communication between said control chamber (17) and the common rail (10) while in the first position; and isolates the control chamber (17) from the common rail (10) and hydraulically connects the control chamber (17) to the return line (12) while in the second position. 13. The fuel injection system as recited in claim 1, wherein the means (11) for pressurizing the common rail (10) comprise an hydraulic pump of a variable displacement type and a means for controlling the displacement of said pump to achieve desired pressure in the common rail. 14. The fuel injection system as recited in claim 1, wherein the means for pressurizing the common rail (10) comprise an hydraulic pump of a fixed displacement type and a means for controlling the rotational speed of said pump to achieve desired pressure in the common rail. 15. The fuel injection system as recited in claim 14, wherein said hydraulic pump is driven by the starter motor of the engine. 16. The fuel injection system as recited in claim 1, wherein the pressure in the common rail (10) can be set to a maximum value of 600 bar.

CROSS REFERENCE TO RELATED APPLICATIONS The present application is a continuation patent application of International Application No. PCT/SE03/00435 filed 14 Mar. 2003 which was published in English pursuant to Article 21(2) of the Patent Cooperation Treaty. International Application No. PCT/SE03/00435 claims priority to Swedish Application No. 0200944-7 filed 26 Mar. 2002 and claims the benefit of United States Provisional Application No. 60/319,538 filed 9 Sep. 2002. Said applications are expressly incorporated herein by reference in their entireties. BACKGROUND OF INVENTION 1. Technical Field The present invention relates to apparatus for injecting fuel into internal combustion engines, particularly compression ignition engines. 2. Background The common means of injecting fuel into modern diesel engines can be divided in two functionally different groups: mechanically actuated systems and common rail systems. The majority of heavy-duty diesel engines for commercial vehicles utilize mechanically actuated, electronically controlled unit injector/unit pump systems. The light duty diesel engine market is dominated by either pump-line-nozzle mechanically actuated fuel injection systems (FIE) or so called high pressure common rail systems. There are several types of mechanically actuated unit injectors/pumps. All of them are capable of creating very high injection pressures with relatively good hydraulic/mechanical efficiency, which is one of their most important advantages over the common rail systems. Another advantage is significantly better durability. Durability of high pressure common rail systems is inferior to mechanically actuated systems largely due to constant exposure of its elements to maximum fuel pressure which is required for injection. Yet another significant advantage of mechanically actuated unit injection systems is their natural ability to achieve favorable injection rate development during a single injection. High pressure common rail systems cannot easily provide such injection characteristic and, when their inherent square-shaped injection trace pattern becomes desirable in some engine operating points, the contemporary unit injectors with a direct nozzle control valve can shape an injection in this way just as well. This affords the latter systems better flexibility in injection rate shaping. On the other hand, high pressure common rail systems have certain advantages over the mechanically actuated injection systems. Among those most important for the commercial vehicle engines have almost unlimited injection timing flexibility and ease of achieving multiple injections. Such an ability of a fuel injection system gains importance with the introduction of various types of diesel exhaust aftertreatment devices and advances in the development of alternative combustion processes like HCCl. The reliance of the mechanically actuated systems on a cam driving the pumping plunger can significantly restrict their ability to fulfill the requirements to injection timing and fuelling of multiple injections. The other advantage of a high pressure common rail system over a mechanical unit injection system can be lower parasitic drive power losses when operating at very low engine loads and idle. At such conditions, high pressure common rail systems also have better accuracy of fuel delivery than a mechanically actuated unit injection system with a large plunger diameter. Finally, mechanically actuated unit injection systems can be a source of excessive mechanical noise generated by both the FIE itself and the drivetrain transmitting torque to actuate the system. Such excessive noise is especially conspicuous at engine idle. The operation of the high pressure common rail systems does not significantly contribute to the total engine noise at any operating point. U.S. Pat. No. 6,247,450 by Jiang discloses a system consisting of a mechanically actuated unit injector with a control valve and a common rail. In that system, the common rail pressure is regulated at relatively low levels and the fuel under this pressure can be fed into the unit injector through a metering orifice that is opened at a certain retracted position of the plunger of the unit injector, and closed at other plunger positions. Variation of common rail pressure and the duration of opening of the metering orifice determine the amount of fuel filling the plunger chamber. During a pumping stroke of the plunger, the metering orifice is closed and fuel is pressurized in the plunger chamber, which is appropriately sized to allow for necessary injection pressure to be reached. The plunger chamber is connected to the inlet of a conventional spring-closed nozzle via a control valve. Upon reaching a required pressure level, the control valve can be opened to transmit the pressurized fuel to the nozzle and commence injection. To end injection, the valve closes and the nozzle is closed by the return spring. Such a system relies on the plunger being stationary at the maximum lift and keeping the pressure created during the pumping stroke to provide flexibility in injection timing. Fuel injection cannot possibly take place during most of the retraction and pumping strokes of the plunger due to the metering orifice being closed. Clearly, the system is not designed to inject at any other time but when the plunger is close to the maximum lift, because even if the control valve were opened during the fuel metering phase and common rail pressure were set above the spring opening pressure of the nozzle, the pressure drop across the metering orifice that is necessary to achieve the fuel metering function of the system, would have prevented injection. Apart from a restricted injection timing range, the system of the U.S. Pat. No. 6,247,450 suffers from a number of other drawbacks, namely, unfavorable shape of injection rate trace both in the beginning and end of injection, restricted range of injection pressures etc. The other prior art FIE which can be considered relevant to the present invention is that referred to as pressure/time metering unit injection system introduced into the market by Cummins Inc. Examples of such system can be found in U.S. Pat. Nos. 3,544,008, 4,092,964 and 5,445,323. A system of this type contains a pressurized fuel common rail feeding unit injectors. However, the function of the common rail is not to directly inject fuel into the engine, but to facilitate fuel metering into the plunger chamber which will be displaced through the nozzle during the pumping stroke of the plunger. Such systems thus have a limited injection timing range and need to utilize the mechanical actuation every time an injection is due. SUMMARY OF INVENTION The subject of the present invention is a new mechanical unit injection system with common rail functionality. The purpose of the invention is to allow the mechanical injection actuation and the common rail principles to be used selectively at such conditions that permit utilization of their respective advantages, and to be selectively de-activated at other conditions where their respective drawbacks could adversely affect the performance of the engine. A primary object of the invention is to provide a fuel injection system allowing the mechanical injection actuation and the common rail principles to be used selectively at such conditions that permit utilization of their respective advantages, and to be selectively de-activated at other conditions to avoid their respective disadvantages. A more specific object of the invention is to provide a fuel injection system with an expanded range of possible injection timings compared to the known mechanically actuated injection systems, so that injection could occur at any point in engine's revolution; with an expanded range of possible injection pressures compared to what is feasible for the known high pressure common rail systems; and with an enhanced injection rate shaping capability. Such a system will allow an exclusive use of the common rail operating principle at idle and low loads to reduce the engine noise and an exclusive use of the mechanical actuation principle at such conditions where high injection pressure is necessary, thereby permitting the design of the common rail part of the system to be relatively simple and durable due to relatively low maximum rail pressure. Such a system will, using both operating principles by choosing an appropriate timing of energization of a control valve, be able to achieve a so-called “boot”-shaped injection in addition to other types of rate shaping which are known to be possible for mechanically actuated unit injectors and common rail systems, such as a square or triangular injection rate traces, pilot injections, high-pressure post injections and late post injections. Another specific object of the present invention is to provide a fuel injection system that, in addition to the features described above, will have an intrinsic protection against system overpressure. BRIEF DESCRIPTION OF DRAWINGS FIGS. 1 to 10 are diagrammatic views of various embodiments of the present invention which will be described in greater detail hereinbelow. DETAILED DESCRIPTION In accordance with a first embodiment of the present invention that is shown in FIG. 1, a fuel injector 1 there is provided that incorporates a conventional, normally closed nozzle 2 and an electrically operated nozzle control valve (NCV) 3. A mechanically actuated means 4 is also provided for pressurizing fuel and comprises (includes, but is not limited to) a cam-driven plunger 5 with a cam 6 and a plunger chamber 7. There is a return spring 8 and an electrically operated valve 9 and a common rail 10 typically serving a set of said fuel injectors and mechanically actuated means in an engine (not shown). There is also a means 11 for pressurizing the common rail and regulating pressure in it at a required level. A return line 12 is provided with a relatively low pressure and a fuel tank 13. An electronic control unit (not shown) governs the pressure in the common rail 10 and controls valves 3 and 9. Fuel injector 1 is designed to operate as a high pressure common rail injector of the type well known from the prior art. As is typical to such known injectors, injector 1 contains a spring 14 biasing a needle 15 to close the nozzle 2; a control piston 16 with a control chamber 17 arranged such that higher pressure in the control chamber tends to urge the control piston to push onto the needle 15 to close the nozzle; an input throttle 18 and an outlet port 19. The input throttle 18 connects the control chamber 17 with the plunger chamber 7 and the outlet port 19 connects the control chamber with the NCV 3. The NCV can, upon receiving a command, open and connect the outlet port 19 to the return line 12. The flow areas of the input throttle, outlet port and the NCV are chosen such that an opening of the NCV causes a pressure drop in the control chamber that is sufficient to allow the pressure acting on a differential area of the needle 15 to open the nozzle 2. Also typical to the known high pressure common rail injectors, the outlet port 19 and the control piston 16 are designed such that the control piston is able to restrict the outlet port at a position corresponding to an open nozzle, thereby limiting the leakage of pressurized fuel through the input throttle 18, output port 19 and open control valve 3 to the return line 12. The plunger chamber 7 is connected to the inlet of the nozzle 2. The plunger chamber can be connected to or disconnected from the common rail 10, depending on the state of the control valve 9. The fuel injection system works as follows: the fuel pressure in the common rail 10 is maintained at a certain constant level that is set in accordance with requirements of a particular operating condition of the engine. When a high injection pressure is not required for the injection, for example, with the engine at idle or relatively low load point, the control valve 9 remains open throughout the entire engine cycle. During the pumping stroke of the plunger 5, the fuel is displaced through the control valve 9 back to the common rail such that there is very little pressure build-up in the plunger chamber 7 and, correspondingly, little wind-up of the engine transmission driving the plunger. To start an injection, the NCV 3 opens, the pressure in the control chamber 17 falls allowing the control piston 16 and the needle 15 to lift up and open the nozzle. Then, fuel is injected under the common rail pressure through the open nozzle, until the NCV is closed again. Following the closure of the NCV, the pressure in the control chamber 17 rises back to the level of the common rail pressure and the control piston 16, assisted by the spring 14, closes the nozzle. This mode of operation will be further referred to as the common rail or CR mode. It will be understood that for the CR operational mode to work, the difference between the pressures in the common rail 10 and the return line 12 should be bigger than the spring opening pressure of the nozzle 2, said spring opening pressure being defined by the pre-load of the spring 14 and the size of the differential area of the closed needle 15. The CR operational mode allows to reduce the mechanical noise of the injection system by eliminating the windup and rapid release of the wound-up transmission driving the mechanical actuation means, that is characteristic to the mechanically actuated FIE and, particularly, unit injectors. The availability of the common rail pressure also allows for fuel injection at any point of the engine cycle. Maximum design limit on the working pressure in the common rail will be a compromise between the cost, useful life and other parameters limiting maximum pressure on one hand and, on the other hand, the benefits such as injection timing flexibility, noise reductions and other improved engine characteristics. Thus, a typical maximum working pressure in the common rail can be between 200 and 600 bar. When a higher injection pressure is required, the control valve 9 is briefly closed during the pumping stroke of the plunger 5. This will cause a pressure increase in the plunger chamber 7, at the input throttle 18 and the inlet of the nozzle 2. When a certain desired pressure is achieved, the NCV opens and injection takes place as described above. The end of injection depends on the relative timing of closing of the NCV and opening of the control valve 9. This mode of operation resembles the functional sequence of electronically controlled mechanically actuated unit injectors known in the prior art and will be further referred to as the EUI mode of operation. By means of utilizing the EUI mode of operation the present invention can achieve very high injection pressures that are characteristic to the known unit injector and unit pump systems. At the same time, the present invention does not have the drawbacks of the high pressure common rail systems associated with having very high pressure in the common rail and other volumes, because the high pressure is kept to relatively small volumes by the closed control valve 9. In fact, the common rail pressure during the EUI operational mode can be reduced down to a very low lever that is just enough to ensure reliable filling of the plunger chamber 7 during the retraction stroke of the plunger, typically between 4 and 6 bar. In another embodiment of the present invention shown in FIG. 2, the system is designed in the same way, but a non-return valve 20 is installed between the inlet of the nozzle 2 and the common rail 10, with its input connected to the common rail. Valve 20 opens during the return or retraction stroke of the plunger 5 to reduce the pressure drop between the plunger chamber 7 and the common rail, which in the absence of the valve 20 could lead to too low a pressure at the inlet of the nozzle 2 for the CR mode of injection to work. The valve 20 is therefore employed to allow for an injection during the retraction stroke of the plunger. Alternatively, it permits the use of a control valve 9 with a smaller flow area. That, in turn, can improve the control valve's response times, reduce its dimensions, electrical power consumption etc. The above described principle for controlling the movement of the needle 15 can be inadequate when a higher needle opening and closing velocity is required. That can be overcome by the use of a three-way valve and suitable modification of the hydraulic circuit. The FIGS. 3 and 4 show another embodiment of the invention in which a three-way needle control valve 3 is installed between the plunger chamber 7 and the control chamber 17. The control chamber's only connection is to the NCV, which can alternatively connect the control chamber 17 to the source of pressure (as shown in the figure) or to the return line 12 with low pressure. Opening of the NCV closes the connection of the control chamber to the source of pressure and opens the return line connection, so that the fuel can be evacuated quickly allowing for a faster opening of the needle. Closing of the NCV disconnects the control chamber 17 from the return line and reconnects it to the pressure source, which can also close the nozzle faster. Identically to the embodiment shown in FIG. 2, a non-return valve 20 connected by its inlet to the common rail and outlet to the nozzle 2 may be used as shown in FIG. 4 to expand the range of possible injection timings of the system and reduce the maximum necessary flow area of the control valve 9. Still another embodiment shown in FIG. 5 incorporates a three position/three-way control valve 9 between the plunger chamber 7 and common rail 10. The control valve 9 can alternatively connect the plunger chamber 7 to the common rail or to the return line 12, or isolate the chamber from both of them. The rest of the design is identical to that shown in FIG. 3. The advantage of configuring the present invention according to the embodiment of FIG. 5 is that a so-called “spill end” of injection can be used where necessary. The CR mode of operation is achieved by opening the NCV and thereby releasing the pressure from the control chamber 17, which in turn allows the nozzle 2 to open. During a CR-mode injection, fuel is supplied to the nozzle from the common rail through the open control valve 9 as shown in FIG. 5. This position of the valve 9 will be referred to as a first position. Closing the NCV raises the pressure in the control chamber 17 and eventually closes the nozzle. Any fuel displaced by the plunger 5 during the pumping stroke passes back to the common rail through the valve 9, which prevents significant extra pressure from being generated in the system and therefore effectively eliminates wind-up and release of the plunger driving mechanism. In the EUI mode of operation, the control valve 9 is switched from the first to a second position during the pumping stroke of the plunger 5. In the second position, valve 9 isolates the plunger chamber 7 from both common rail and return line. Pressure in the system then rises and, upon reaching a desired pressure level, the NCV is open allowing the needle 15 to open the nozzle as described above. Fuel injection occurs at a high pressure generated by the plunger. To end an injection, several options are available. Typically, the NCV will close re-pressurizing the control chamber 17. If a pressure-backed end of injection is desired, the control valve 9 can be either left closed in the second position for a period of time corresponding to the closing duration of the nozzle, or switched back to the first position. The nozzle will then be closed at a high pressure in the control chamber 17, which will be assisting the return spring 14 in closing the nozzle quicker. If a spill end of injection is desired, the control valve 9 will be switched to a third position connecting the plunger chamber 7 to the return line 12 and isolating it from the common rail. By this means, the nozzle will be closed with the return spring 14 while fuel pressure in the nozzle is low. In case a simultaneous use of the spill end and the pressure-backed end of injection is an advantage, the NCV can be connected directly to the common rail as shown in FIG. 6. To end an injection, the NCV is switched to the position where it closes the connection between the control chamber 17 and the return line 12 and connects the control chamber with the common rail. The control valve 9 is switched to the third position to release the pressure from the plunger chamber and the nozzle, and the needle 15 closes the nozzle under the combined action of the return spring 14 and pressure in the control chamber 17. In this embodiment of the present invention, a relatively weak return spring 14 of the nozzle can be used, which can allow for lower minimum common rail pressure setting that can be used for the CR mode of operation. To reduce complexity of the injection systems shown in FIGS. 5 and 6, a two-way nozzle control valve may be used instead of the three-way valve, as shown in FIGS. 7 and 8. The functional sequence of the systems per FIGS. 7 and 8 corresponds to that of the systems depicted in FIGS. 5 and 6 respectively. The design and function of the two-way NCV arrangement is described earlier in this section. The embodiments of the present invention shown in FIGS. 6 and 8 can be advantageous due to their intrinsically better protection against system overpressure. This is due to the inlet of the control chamber 17 being connected to the common rail (either directly or via NCV) rather than to the plunger chamber 7, as is the case in the other embodiments of the invention (FIGS. 1-5, 7) and in many a prior art design. In these latter systems, a failure of the NCV to open leaves no way for the pressure created during the pumping stroke of the plunger to escape, because pressure build-up occurs simultaneously in the nozzle and in the control chamber 17, and cannot open the nozzle. This can cause serious mechanical damage of the FIE and the engine. Connecting the control chamber 17 to the common rail as in FIGS. 6 and 8 sets a hardware limit to the maximum pressure that can be achieved in the injector with the closed nozzle. This pressure limit is determined by the preload of the return spring 14, diameter of the control piston 16 and pressure in the common rail 10, which in turn can be easily limited by a relief valve. Such principle of hardware limiting of the maximum pressure can be used in any other embodiment of the present invention as described above. An example of this is given in FIGS. 9a,b. Yet another embodiment of the present invention shown in FIG. 10 incorporates an electrically operated nozzle control valve 3 which directly controls the position of the needle 15 of the nozzle 2. The needle 15 can be mechanically connected to the moveable armature 21 of the NCV 3. The CR and/or the EUI operational modes, as well as their combinations, are realized in this embodiment in the same way as previously described. The NCV can be solenoid-actuated or, preferably, piezo-actuated to achieve fast and precise control of the position of the needle 15. All of the embodiments of the present invention described herein are capable of rate shaping of the injection process in several ways. Variable needle opening pressure (NOP) is achieved during the EUI operational mode by suitably delaying the timing of the opening of the NCV 3 relative to closing of the control valve 9. For the variants shown in FIGS. 6, 8 and 9, high maximum NOP can be set by using the control piston 16 of a bigger diameter than the diameter of the needle Selecting an higher NOP gives a more square-shaped injection rate trace, lower NOP will give a gradual pressure rise during an injection and the trace will have a triangular shape. Different combinations of multiple injections such as pilot, split and post injections that are known to be possible for both EUI and CR FIE are also achievable by the present invention. Additionally, the invention allows for a boot-shaped injection with variable pressure level and variable duration of the boot phase. To achieve such an injection pattern, both the CR and EUI operational modes can be used within a single injection cycle, with NCV opening prior to the start of pumping stroke of the plunger. The means 11 for pressurizing the common rail 10 and regulating the fuel pressure can incorporate a fixed displacement pump and a pressure regulator that is essentially a controllable relief valve. The displacement of the pump is chosen such that maximum required pressure in the CR can be achieved at any engine operating condition. When a lower pressure is required compared to what is achievable at the particular condition, the relief valve will return the excess fuel from the outlet of the pump back to the fuel tank. Alternatively, a variable displacement pump can be used such that the delivery of the pump can be adjusted at any operating condition to maintain necessary CR pressure without opening a relief valve, which in such a system will function as a safety relief valve. The use of a variable displacement pump will allow reduced power losses, but such pumps are generally more expensive than fixed displacement pumps. Other configurations of the means 11 can be utilized in the present invention, for example, a fixed displacement pump driven by the engine via a variable ratio transmission, either mechanical, hydro-mechanical or electrical. In the latter case the starter motor of the engine can be used for the purpose, thereby avoiding the cost of an additional dedicated electrical motor for the pump. While the present invention has been disclosed in connection with the preferred embodiments thereof, it should be understood that there might be other embodiments that fall within the spirit and scope of the invention as defined by the following claims.

<SOH> BACKGROUND OF INVENTION <EOH>1. Technical Field The present invention relates to apparatus for injecting fuel into internal combustion engines, particularly compression ignition engines. 2. Background The common means of injecting fuel into modern diesel engines can be divided in two functionally different groups: mechanically actuated systems and common rail systems. The majority of heavy-duty diesel engines for commercial vehicles utilize mechanically actuated, electronically controlled unit injector/unit pump systems. The light duty diesel engine market is dominated by either pump-line-nozzle mechanically actuated fuel injection systems (FIE) or so called high pressure common rail systems. There are several types of mechanically actuated unit injectors/pumps. All of them are capable of creating very high injection pressures with relatively good hydraulic/mechanical efficiency, which is one of their most important advantages over the common rail systems. Another advantage is significantly better durability. Durability of high pressure common rail systems is inferior to mechanically actuated systems largely due to constant exposure of its elements to maximum fuel pressure which is required for injection. Yet another significant advantage of mechanically actuated unit injection systems is their natural ability to achieve favorable injection rate development during a single injection. High pressure common rail systems cannot easily provide such injection characteristic and, when their inherent square-shaped injection trace pattern becomes desirable in some engine operating points, the contemporary unit injectors with a direct nozzle control valve can shape an injection in this way just as well. This affords the latter systems better flexibility in injection rate shaping. On the other hand, high pressure common rail systems have certain advantages over the mechanically actuated injection systems. Among those most important for the commercial vehicle engines have almost unlimited injection timing flexibility and ease of achieving multiple injections. Such an ability of a fuel injection system gains importance with the introduction of various types of diesel exhaust aftertreatment devices and advances in the development of alternative combustion processes like HCCl. The reliance of the mechanically actuated systems on a cam driving the pumping plunger can significantly restrict their ability to fulfill the requirements to injection timing and fuelling of multiple injections. The other advantage of a high pressure common rail system over a mechanical unit injection system can be lower parasitic drive power losses when operating at very low engine loads and idle. At such conditions, high pressure common rail systems also have better accuracy of fuel delivery than a mechanically actuated unit injection system with a large plunger diameter. Finally, mechanically actuated unit injection systems can be a source of excessive mechanical noise generated by both the FIE itself and the drivetrain transmitting torque to actuate the system. Such excessive noise is especially conspicuous at engine idle. The operation of the high pressure common rail systems does not significantly contribute to the total engine noise at any operating point. U.S. Pat. No. 6,247,450 by Jiang discloses a system consisting of a mechanically actuated unit injector with a control valve and a common rail. In that system, the common rail pressure is regulated at relatively low levels and the fuel under this pressure can be fed into the unit injector through a metering orifice that is opened at a certain retracted position of the plunger of the unit injector, and closed at other plunger positions. Variation of common rail pressure and the duration of opening of the metering orifice determine the amount of fuel filling the plunger chamber. During a pumping stroke of the plunger, the metering orifice is closed and fuel is pressurized in the plunger chamber, which is appropriately sized to allow for necessary injection pressure to be reached. The plunger chamber is connected to the inlet of a conventional spring-closed nozzle via a control valve. Upon reaching a required pressure level, the control valve can be opened to transmit the pressurized fuel to the nozzle and commence injection. To end injection, the valve closes and the nozzle is closed by the return spring. Such a system relies on the plunger being stationary at the maximum lift and keeping the pressure created during the pumping stroke to provide flexibility in injection timing. Fuel injection cannot possibly take place during most of the retraction and pumping strokes of the plunger due to the metering orifice being closed. Clearly, the system is not designed to inject at any other time but when the plunger is close to the maximum lift, because even if the control valve were opened during the fuel metering phase and common rail pressure were set above the spring opening pressure of the nozzle, the pressure drop across the metering orifice that is necessary to achieve the fuel metering function of the system, would have prevented injection. Apart from a restricted injection timing range, the system of the U.S. Pat. No. 6,247,450 suffers from a number of other drawbacks, namely, unfavorable shape of injection rate trace both in the beginning and end of injection, restricted range of injection pressures etc. The other prior art FIE which can be considered relevant to the present invention is that referred to as pressure/time metering unit injection system introduced into the market by Cummins Inc. Examples of such system can be found in U.S. Pat. Nos. 3,544,008, 4,092,964 and 5,445,323. A system of this type contains a pressurized fuel common rail feeding unit injectors. However, the function of the common rail is not to directly inject fuel into the engine, but to facilitate fuel metering into the plunger chamber which will be displaced through the nozzle during the pumping stroke of the plunger. Such systems thus have a limited injection timing range and need to utilize the mechanical actuation every time an injection is due.

<SOH> SUMMARY OF INVENTION <EOH>The subject of the present invention is a new mechanical unit injection system with common rail functionality. The purpose of the invention is to allow the mechanical injection actuation and the common rail principles to be used selectively at such conditions that permit utilization of their respective advantages, and to be selectively de-activated at other conditions where their respective drawbacks could adversely affect the performance of the engine. A primary object of the invention is to provide a fuel injection system allowing the mechanical injection actuation and the common rail principles to be used selectively at such conditions that permit utilization of their respective advantages, and to be selectively de-activated at other conditions to avoid their respective disadvantages. A more specific object of the invention is to provide a fuel injection system with an expanded range of possible injection timings compared to the known mechanically actuated injection systems, so that injection could occur at any point in engine's revolution; with an expanded range of possible injection pressures compared to what is feasible for the known high pressure common rail systems; and with an enhanced injection rate shaping capability. Such a system will allow an exclusive use of the common rail operating principle at idle and low loads to reduce the engine noise and an exclusive use of the mechanical actuation principle at such conditions where high injection pressure is necessary, thereby permitting the design of the common rail part of the system to be relatively simple and durable due to relatively low maximum rail pressure. Such a system will, using both operating principles by choosing an appropriate timing of energization of a control valve, be able to achieve a so-called “boot”-shaped injection in addition to other types of rate shaping which are known to be possible for mechanically actuated unit injectors and common rail systems, such as a square or triangular injection rate traces, pilot injections, high-pressure post injections and late post injections. Another specific object of the present invention is to provide a fuel injection system that, in addition to the features described above, will have an intrinsic protection against system overpressure.

20040317

20070320

20050106

63299.0

MOULIS, THOMAS N

FUEL INJECTION SYSTEM

UNDISCOUNTED

CONT-ACCEPTED

ACCEPTED

MULTIPLE DIELECTRIC FINFET STRUCTURE AND METHOD

Disclosed is a method and structure for a fin-type field effect transistor (FinFET) structure that has different thickness gate dielectrics covering the fins extending from the substrate. These fins have a central channel region and source and drain regions on opposite sides of the channel region. The thicker gate dielectrics can comprise multiple layers of dielectric and the thinner gate dielectrics can comprise less layers of dielectric. A cap comprising a different material than the gate dielectrics can be positioned over the fins.

1. A fin-type field effect transistor (FinFET) structure comprising: a substrate; fins extending from said substrate; and gate dielectrics covering said fins, wherein said gate dielectrics have different thickness. 2. The FinFET structure in claim 1, wherein said fins are utilized in different types of transistors on said substrate, and wherein one type of transistor includes gate dielectrics having a first thickness and a second type of transistor includes gate dielectrics having a second thickness different than said first thickness. 3. The FinFET structure in claim 1, wherein said fins are utilized in multiple-fin transistors. 4. The FinFET structure in claim 1, wherein thicker gate dielectrics comprise multiple layers of dielectric and thinner gate dielectrics comprise less layers of dielectric. 5. The FinFET structure in claim 1, further comprising a cap over said fins. 6. The FinFET structure in claim 5, wherein said cap comprises a different material than said gate dielectrics. 7. A fin-type field effect transistor (FinFET) structure comprising: a substrate; fins extending from said substrate, wherein said fins comprise a central channel region and source and drain regions on opposite sides of said channel region; and gate dielectrics covering said channel region of fins, wherein said gate dielectrics have different thickness. 8. The FinFET structure in claim 7, wherein said fins are utilized in different types of transistors on said substrate, and wherein one type of transistor includes gate dielectrics having a first thickness and a second type of transistor includes gate dielectrics having a second thickness different than said first thickness. 9. The FinFET structure in claim 7, wherein said fins are utilized in multiple-fin transistors. 10. The FinFET structure in claim 7, wherein thicker gate dielectrics comprise multiple layers of dielectric and thinner gate dielectrics comprise less layers of dielectric. 11. The FinFET structure in claim 7, further comprising a cap over said fins. 12. The FinFET structure in claim 11, wherein said cap comprises a different material than said gate dielectrics. 13. A fin-type field effect transistor (FinFET) structure comprising: a substrate; fins extending from said substrate; and gate dielectrics covering said fins, wherein said fins are utilized in different types of transistors on said substrate, and wherein a first type of transistor includes gate dielectrics having a first thickness and a second type of transistor includes gate dielectrics having a second thickness different than said first thickness. 14. The FinFET structure in claim 13, wherein said fins are utilized in multiple-fin transistors. 15. The FinFET structure in claim 13, wherein thicker gate dielectrics comprise multiple layers of dielectric and thinner gate dielectrics comprise less layers of dielectric. 16. The FinFET structure in claim 13, further comprising a cap over said fins. 17. The FinFET structure in claim 5, wherein said cap comprises a different material than said gate dielectrics. 18. A method of forming a fin-type field effect transistor (FinFET) structure, said method comprising: patterning fins on a substrate; forming a first gate dielectric on said fins; protecting first fins using a mask; removing said first gate dielectric from unprotected second fins; removing said mask from said first fins; and forming an additional gate dielectric on said second fins and on said first gate dielectric that covers said first fins to form different thicknesses of gate dielectrics on said first fins when compared to said second fins. 19. The method in claim 18, further comprising utilizing said fins in different types of transistors on said substrate, wherein one type of transistor includes gate dielectrics having a first thickness and a second type of transistor includes gate dielectrics having a second thickness different than said first thickness. 20. The method in claim 18, further comprising utilizing said fins in multiple-fin transistors. 21. The method in claim 18, wherein said process of forming an additional gate dielectric forms multiple layers of dielectric over said first fins and forms only said additional gate dielectric over said second fins. 22. The method in claim 18, wherein said process of patterning said fins forms a cap over said fins. 23. The method in claim 22, wherein said cap comprises a different material than said gate dielectrics. 24. A method of forming a fin-type field effect transistor (FinFET) structure, said method comprising: patterning fins on a substrate; forming a first gate dielectric on said fins; protecting first fins using a mask; removing said first gate dielectric from unprotected second fins; removing said mask from said first fins; forming an additional gate dielectric on said second fins and on said first gate dielectric that covers said first fins to form different thicknesses of gate dielectrics on said first fins when compared to said second fins; doping ends of said fins to form source and drain regions separated by a central channel regions of said fins; and forming a gate conductor over said channel regions, wherein said gate dielectrics insulate said channel regions from said gate conductor. 25. The method in claim 24, further comprising utilizing said fins in different types of transistors on said substrate, wherein one type of transistor includes gate dielectrics having a first thickness and a second type of transistor includes gate dielectrics having a second thickness different than said first thickness. 26. The method in claim 24, further comprising utilizing said fins in multiple-fin transistors. 27. The method in claim 24, wherein said process of forming an additional gate dielectric forms multiple layers of dielectric over said first fins and forms said additional gate dielectric only over said second fins. 28. The method in claim 24, wherein said process of patterning said fins forms a cap over said fins. 29. The method in claim 28, wherein said cap comprises a different material than said gate dielectrics. 30. A method of forming a fin-type field effect transistor (FinFET) structure, said method comprising: patterning fins on a substrate; forming a first gate dielectric on said fins; protecting first fins using a mask; removing said first gate dielectric from unprotected second fins; removing said mask from said first fins; forming an additional gate dielectric on said second fins and on said first gate dielectric that covers said first fins to form different thicknesses of gate dielectrics on said first fins when compared to said second fins; and utilizing said fins in different types of transistors on said substrate, wherein one type of transistor includes gate dielectrics having a first thickness and a second type of transistor includes gate dielectrics having a second thickness different than said first thickness. 31. The method in claim 30, further comprising utilizing said fins in multiple-fin transistors. 32. The method in claim 30, wherein said process of forming an additional gate dielectric forms multiple layers of dielectric over said first fins and forms said additional gate dielectric only over said second fins. 33. The method in claim 30, wherein said process of patterning said fins forms a cap over said fins. 34. The method in claim 33, wherein said cap comprises a different material than said gate dielectrics.

BACKGROUND OF INVENTION 1. Field of the Invention The present invention generally relates to Fin-type field effect transistors (FinFET) and more particularly to an improved FinFET structure that includes multiple gate dielectric thicknesses. 2. Description of the Related Art As the need to decrease the size of transistors continues, new and smaller types of transistors are created. One recent advance in transistor technology is the introduction of fin type field effect transistors that are known as FinFETs. U.S. Pat. No. 6,413,802 to Hu et al. (hereinafter “Hu patent”), which is incorporated herein by reference, discloses a FinFET structure that includes a center fin that has a channel along its center and source and drains at the ends of the fin structure. A gate conductor covers the channel portion. While FinFETs structures reduce the size of transistor-based devices, it is still important to continue to improve FinFETs. The invention described below provides a method and structure which improves the performance of FinFETs. SUMMARY OF INVENTION The invention provides a method of forming a fin-type field effect transistor (FinFET) structure that begins by patterning fins on a substrate and forming a first gate dielectric on the fins. Then, the invention protects first fins using a mask and removes the first gate dielectric from unprotected second fins. After removing the mask from the first fins, the invention forms an additional gate dielectric on the second fins and on the first gate dielectric that covers the first fins. This forms different thicknesses of gate dielectrics on the first fins when compared to the second fins. This process also forms multiple layers of dielectric over the first fins and forms the additional gate dielectric only over the second fins. Processing steps used to complete the FinFET structure include doping ends of the fins to form source and drain regions separated by a central channel regions of the fins, and forming a gate conductor over the channel regions. The gate dielectrics insulate the channel regions from the gate conductor. The invention can utilize the fins in different types of transistors on the substrate. In this situation, one type of transistor would include gate dielectrics having a first thickness and a second type of transistor would include gate dielectrics having a second thickness different than the first thickness. Also, the invention can utilize the fins in multiple-fin transistors. This process produces a fin-type field effect transistor (FinFET) structure that has different thickness gate dielectrics covering the fins extending from the substrate. These fins have a central channel region and source and drain regions on opposite sides of the channel region. Again, the thicker gate dielectrics can comprise multiple layers of dielectric and the thinner gate dielectrics comprise less layers of dielectric. A cap comprising a different material than the gate dielectrics can be positioned over the fins. The use of different voltage ranges on separate regions of circuit areas (core, I/O, capacitors, etc.) requires different dielectric thickness to optimize device performance and reliability. This invention proposes a multi-thickness dielectric FinFET structure and method to map this into future technologies. This invention uses multiple gate dielectrics on FinFET designs to optimize device performance/reliability and a method to fabricate them. By using a multiple dielectric design the invention avoids the density and performance penalties associated with complicated stacking schemes designed to keep device electric fields within the thinner dielectric imposed limits. This invention also extends the scaling capabilities of FINFETs. These, and other, aspects and objects of the present invention will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following description, while indicating preferred embodiments of the present invention and numerous specific details thereof, is given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications. BRIEF DESCRIPTION OF DRAWINGS The invention will be better understood from the following detailed description with reference to the drawings, in which: FIG. 1 is a schematic diagram of a partially completed FinFET structure; FIG. 2 is a schematic diagram of a partially completed FinFET structure; FIG. 3 is a schematic diagram of a partially completed FinFET structure; FIG. 4 is a schematic diagram of a partially completed FinFET structure; FIG. 5 is a schematic diagram of a partially completed FinFET structure; FIG. 6 is a schematic diagram of a partially completed FinFET structure; FIG. 7 is a schematic diagram of a partially completed FinFET structure; and FIG. 8 is a flow diagram illustrating a preferred method of the invention. DETAILED DESCRIPTION The present invention and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. It should be noted that the features illustrated in the drawings are not necessarily drawn to scale. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the present invention. The examples used herein are intended merely to facilitate an understanding of ways in which the invention may be practiced and to further enable those of skill in the art to practice the invention. Accordingly, the examples should not be construed as limiting the scope of the invention. As shown in FIG. 5, one embodiment of the invention provides a fin-type field effect transistor (FinFET) structure that has different thickness gate dielectrics 502, 504 covering the fins 112-114 extending from the substrate 110. The thicker gate dielectrics 504 can comprise multiple layers of dielectric (200 and 500) and the thinner gate dielectrics 502 comprise less layers of dielectric (only 500). A cap 116 comprising a different material than the gate dielectrics can be positioned over the fins 112-114. As shown in FIG. 6, the fins 66 have a central channel region covered by a gate conductor 64, and source 60 and drain 62 regions on opposite sides of the channel region. FIGS. 1-5 illustrates one exemplary methodology utilized to form the inventive structure. More specifically, FIG. 1 illustrates fins 112-114 and caps 116 patterned on a substrate 110. FIG. 2 illustrates a first gate dielectric 200 that is grown on the fins 112-114. Then, the invention protects first fins 114 using a mask 300, as shown in FIG. 3. In FIG. 4, the invention removes the first gate dielectric from unprotected second fins 112, 113. After removing the mask from the first fins (as shown and FIG. 5), the invention forms an additional gate dielectric 500 on the second fins 112, 113 and on the first gate dielectric 200 that covers the first fins 114. This forms different thicknesses of gate dielectrics 504 on the first fins 114 when compared to the thickness of the dielectrics 502 on the second fins 112, 113. This process also forms multiple layers of dielectric 200, 500 over the first fins 114 and forms only the additional gate dielectric 500 over the second fins. As shown in FIG. 6 and 7, additional processing steps, such as those described in the Hu patent are used to complete the FinFET structure. For example, the ends of the fins 66 are doped to form source 60 and drain 62 regions separated by a central channel region. Gate conductors 64 are formed over the channel regions of the fins 66. The gate dielectrics 200, 500 insulate the channel regions from the gate conductor 64. While a limited number of types of FinFETs are shown in the drawings, one ordinarily skilled in the art would readily understand that the invention can utilize the fins in many different types of transistors on the substrate. For example, the invention can form complementary transistors on the same substrate, or can form transistors with different voltage requirements on different areas of the substrate. Therefore, in these situations, certain types of transistor would include gate dielectrics having a first thickness and other types of transistor could include gate dielectrics having a second thickness. Also, the invention can utilize the fins in multiple-fin transistors. Further, one ordinarily skilled in the art would clearly understand that the invention is not limited to only two different thicknesses of gate dielectrics. To the contrary, any number of gate dielectric thicknesses can be formed with the invention by simply repeating the masking and depositing processes shown in FIGS. 3-5. FIG. 8 illustrates the methodology of the invention in flowchart form. More specifically, in item 800, the invention patterns fins on a substrate and in item 802, the invention forms a first gate dielectric on the fins. Then, the invention protects first fins using a mask (804) and removes the first gate dielectric from unprotected second fins 806. After removing the mask from the first fins, the invention forms an additional gate dielectric on the second fins and on the first gate dielectric that covers the first fins 808. This forms different thicknesses of gate dielectrics on the first fins when compared to the second fins. For example, one gate dielectric could be more than twice as thick as the other gate dielectric. This process also forms multiple layers of dielectric over the first fins and forms only the additional gate dielectric over the second fins. Forming n layers on one set of FINs, n−1 on another set, n−2 on a third set etc., so the process is repeatable and flexible. Processing steps used to complete the FinFET structure include doping ends of the fins to form source and drain regions 810 separated by a central channel regions of the fins, and forming a gate conductor over the channel regions 812. In addition, while one methodology is discussed above, variations on this methodology are intended to be included within the invention. For example, while FIG. 4 illustrates the removal of the first gate dielectric 200 from selected fins, the inventive process can instead selectively retard oxide growth in one set of FINS (112 and 113) (for example by N2 implantation into the Fin sidewall) and then perform a single oxidation which would yield a first thickness on 112/113 and a second thickness (thicker film) on 114. Another aspect of the invention is that after growing layer 200 and protecting FINs 114 the invention etch off layer 200 on FINS 112-113. This has the effect of thinning the body of 112 and 113 as the grown oxide (200) consumes silicon during the growth phase. After layer 500 is grown the FIN bodies of 112 and 113 are thinner than 114 which is scaled in the correct direction, i.e. for higher voltages it is desirable to have a thicker oxide and thicker FIN body. Additionally, any type of dielectric that functions properly as a gate dielectric can be used including oxides, nitrides, glasses, silicone, or any of the class of hi-K dielectrics etc. One ordinarily skilled in the art would understand that additional similar methodologies could be employed within the spirit and scope of the invention. The use of different voltage ranges on separate regions of circuit areas (core, I/O, capacitors, etc.) requires different dielectric thickness to optimize device performance and reliability. This invention discloses a multi-thickness dielectric FinFET structure and method to map this into future technologies. This invention uses multiple gate dielectrics on FinFET designs to optimize device performance/reliability and a method to fabricate them. By using a multiple dielectric design, the invention avoids the density and performance penalties associated with complicated stacking schemes designed to keep device electric fields within the thinner dielectric imposed limits. This invention also extends the scaling capabilities of FinFETs. While the invention has been described in terms of preferred embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the appended claims.

<SOH> BACKGROUND OF INVENTION <EOH>1. Field of the Invention The present invention generally relates to Fin-type field effect transistors (FinFET) and more particularly to an improved FinFET structure that includes multiple gate dielectric thicknesses. 2. Description of the Related Art As the need to decrease the size of transistors continues, new and smaller types of transistors are created. One recent advance in transistor technology is the introduction of fin type field effect transistors that are known as FinFETs. U.S. Pat. No. 6,413,802 to Hu et al. (hereinafter “Hu patent”), which is incorporated herein by reference, discloses a FinFET structure that includes a center fin that has a channel along its center and source and drains at the ends of the fin structure. A gate conductor covers the channel portion. While FinFETs structures reduce the size of transistor-based devices, it is still important to continue to improve FinFETs. The invention described below provides a method and structure which improves the performance of FinFETs.

<SOH> SUMMARY OF INVENTION <EOH>The invention provides a method of forming a fin-type field effect transistor (FinFET) structure that begins by patterning fins on a substrate and forming a first gate dielectric on the fins. Then, the invention protects first fins using a mask and removes the first gate dielectric from unprotected second fins. After removing the mask from the first fins, the invention forms an additional gate dielectric on the second fins and on the first gate dielectric that covers the first fins. This forms different thicknesses of gate dielectrics on the first fins when compared to the second fins. This process also forms multiple layers of dielectric over the first fins and forms the additional gate dielectric only over the second fins. Processing steps used to complete the FinFET structure include doping ends of the fins to form source and drain regions separated by a central channel regions of the fins, and forming a gate conductor over the channel regions. The gate dielectrics insulate the channel regions from the gate conductor. The invention can utilize the fins in different types of transistors on the substrate. In this situation, one type of transistor would include gate dielectrics having a first thickness and a second type of transistor would include gate dielectrics having a second thickness different than the first thickness. Also, the invention can utilize the fins in multiple-fin transistors. This process produces a fin-type field effect transistor (FinFET) structure that has different thickness gate dielectrics covering the fins extending from the substrate. These fins have a central channel region and source and drain regions on opposite sides of the channel region. Again, the thicker gate dielectrics can comprise multiple layers of dielectric and the thinner gate dielectrics comprise less layers of dielectric. A cap comprising a different material than the gate dielectrics can be positioned over the fins. The use of different voltage ranges on separate regions of circuit areas (core, I/O, capacitors, etc.) requires different dielectric thickness to optimize device performance and reliability. This invention proposes a multi-thickness dielectric FinFET structure and method to map this into future technologies. This invention uses multiple gate dielectrics on FinFET designs to optimize device performance/reliability and a method to fabricate them. By using a multiple dielectric design the invention avoids the density and performance penalties associated with complicated stacking schemes designed to keep device electric fields within the thinner dielectric imposed limits. This invention also extends the scaling capabilities of FINFETs. These, and other, aspects and objects of the present invention will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following description, while indicating preferred embodiments of the present invention and numerous specific details thereof, is given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.

20040318

20061003

20050922

96584.0

QUINTO, KEVIN V

MULTIPLE DIELECTRIC FINFET STRUCTURE AND METHOD

UNDISCOUNTED

ACCEPTED

ACCEPTED

METHOD AND RELATED APPARATUS FOR CLEARING DATA IN A MEMORY

A computer system includes a processor, and a memory controller electrically connected to the processor and the memory for controlling the accessing operations of the memory. The method includes the processor generating a predetermined logic value and delivering the predetermined logic value to the memory controller, and the memory controller repeatedly overwriting data stored in the plurality of memory units by the predetermined logic value.

1. A method of clearing data in a memory of a computer system, the computer system comprising a processor, and a memory controller electrically connected to the processor and the memory for controlling accessing operations of the memory, the memory comprising a plurality of memory units, the method comprising: a) the processor generating a predetermined logic value, and delivering the predetermined logic value to the memory controller; and b) the memory controller repeatedly overwriting data stored in the plurality of memory units by the predetermined logic value. 2. The method of claim 1 wherein if the plurality of memory units have continuous addresses, a source memory address and a bit length are delivered to the memory controller. 3. The method of claim 1 wherein if the plurality of memory units have discontinuous addresses, a memory address table is provided to the memory controller for writing the predetermined logic value to the plurality of memory units. 4. The method of claim 3 wherein the memory address table comprises a plurality of fields, each field including a physical memory address, a bit length, and a flag for respectively recording a start address, a bit length, and indicating whether data is an end portion. 5. The method of claim 1 wherein the predetermined logic value is “0” or “1”. 6. A computer system comprising: a processor for controlling operations of the computer system; a memory including a plurality of memory units for storing data; and a memory controller electrically connected to the processor and the memory, the memory controller comprising: an address register for storing a plurality of memory addresses corresponding to the plurality of memory units; a data register; and a data clear module for transmitting a predetermined logic value generated by the processor to the data register so that the predetermined logic value overwrites data stored in the plurality of memory units one by one. 7. The computer system of claim 6 wherein if the plurality of memory units have continuous addresses, the data clear module will generate a plurality of memory addresses according to a source memory address and a bit length, and deliver the plurality of memory addresses to the address register so as to write the predetermined logic value to the memory units corresponding to the plurality of memory addresses. 8. The computer system of claim 6 wherein if the plurality of memory units have discontinuous addresses, the data clear module utilizes a memory address table for generating a plurality of memory addresses to the address register, and writes the predetermined logic value to the plurality of memory units corresponding to the plurality of memory addresses. 9. The computer system of claim 8 wherein the memory address table is generated by an operating system of the computer system. 10. The computer system of claim 6 wherein the memory controller is installed in a north bridge circuit. 11. The computer system of claim 10 wherein the north bridge circuit further comprises a display controller to generate image signals for driving a display device of the computer system. 12. The computer system of claim 11 wherein the memory comprises a display memory for storing operation data of the display controller, and a system memory for storing operation data of the processor. 13. The computer system of claim 12 wherein the plurality of memory units are located in the display memory or in the system memory.

BACKGROUND OF INVENTION 1. Field of the Invention The present invention relates to a method and related apparatus for clearing data in a memory, and more particularly, to a method and related apparatus for clearing data in a memory without the involvement of a CPU. 2. Description of the Prior Art FIG. 1 is a schematic diagram of a conventional computer system 10. As shown in FIG. 1, the computer system 10 includes a CPU 12, a north bridge circuit 14, a south bridge circuit 16, a display controller 18, a display 19, a memory 20, a hard disk 22, and an input device 24. The memory 20 includes a plurality of memory units 26 arranged in arrays, i.e., each memory unit 26 corresponds to a column address and a row address. The accessing operations of the memory 20 are controlled via a memory controller 30 positioned in the north bridge circuit 14. The memory controller 30 includes an address register 32 and a data register 34 where the address register 32 is for storing memory addresses, and the data register 34 is for storing data to be written to the memory 20 and data read from the memory 20. For the computer system 10, any executed programs, for example a driver or an application program, require the memory 20 for storing data. When a first application program is executed, a memory block of the memory 20 is designated for storing operation data of the first application program. While the first application program is closed, the memory block must be released so that other programs can use this memory block to store data. In addition to release the memory block, however, the first application program must clear the memory block, by for example overwriting the data stored in each memory unit 26 of the memory block with a logic value “1” or “0”. In such case, a second application program executed thereafter, can correctly access data in the same memory block. If that memory block is not cleared, errors due to misjudgment may occur when the second application program is executed. These errors may even lead to the crash of the computer system 10. Therefore, when a program requires a certain capacity of memory units 26 in the memory 20 to store operation data, that certain capacity of memory units 26 must be overwritten with logic values “1” or “0”. For example, if the CPU 12 executes the program codes of clearing data, the CPU will output the memory addresses corresponding to the memory units 26 to be used to the address register 32. Meanwhile, the CPU 12 will repeatedly output the logic value “1” or “0” to the data register 34. If the capacity of the memory 20 to be used is 3 MB, the CPU 12 will output the logic values “1” to the data register 34 24 million times for clearing 24 million memory units 26 (corresponding to 3 MB capacity) in the memory 20. It can be seen that the CPU 12 spends much time repeatedly outputting the logic value “1” or “0” to the memory 20, thereby reducing its efficiency. In addition to reducing the efficiency of the CPU 12, the limited bandwidth of the front-side bus (FSB) between the CPU 12 and the north bridge circuit 14 is also consumed. This also affects the total efficiency of the computer system 10. SUMMARY OF INVENTION It is therefore a primary objective of the present invention to provide a method and related apparatus of clearing data in a memory for solving the above problems. According to the claimed invention, a method of clearing data in a memory of a computer system is disclosed. The computer system includes a processor, and a memory controller electrically connected to the processor and the memory for controlling the accessing operations of the memory. The method includes the processor generating a predetermined logic value and delivering the predetermined logic value to the memory controller, and the memory controller repeatedly overwriting data stored in the plurality of memory units by the predetermined logic value. The claimed invention further includes a computer system including a processor for controlling operations of the computer system, a memory having a plurality of memory units for respectively storing a data, and a memory controller electrically connected to the processor and the memory. The memory controller includes an address register for storing a plurality of memory addresses corresponding to the plurality of memory units, a data register, and a data clear module for transmitting a predetermined logic value generated by the processor to the data register so that the predetermined logic value overwrites data stored in the plurality of memory units one by one. These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic diagram of a conventional computer system 10. FIG. 2 is a schematic diagram of a computer system according to a first embodiment of the present invention. FIG. 3 is a memory address table of the present invention. FIG. 4 is a schematic diagram of another computer system according to a second embodiment of the present invention. DETAILED DESCRIPTION FIG. 2 is a schematic diagram of a computer system 80 according to a first preferred embodiment of the present invention. As shown in FIG. 2, the computer system 80 includes a CPU 82, a north bridge circuit 84, a south bridge circuit 86, a display controller 88, a memory 90, an input device 92, a hard disk 94, and a display 96. The north bridge circuit 84 has a memory controller 98, and the memory controller 98 includes a data clear module 100, an address register 102, and a data register 104. The memory 90 includes a plurality of memory units 106 arranged in arrays, i.e., each memory unit 106 corresponds to a column address and a row address. The memory controller 98 is for controlling accessing operations of the memory 90. The address register 102 is for storing memory addresses, and the data register 104 is for storing data to be written to the memory 90 or data to be read from the memory 90. The data clear module 100 can output a predetermined logic value (such as “1” or “0”) to overwrite the memory units 106 of the memory 90 so as to clear any data in the memory units 106. Therefore, the memory controller 98 is capable of deleting data stored in the memory in virtue of the installation of the data clear module 100. The mechanism of the data clear module 100 is demonstrated as follows. When the computer system 80 starts, an operating system is loaded first. Then the user inputs an instruction via the input device 92 for executing an application program. The application program will be allotted a portion of the memory units 106 of the memory 90 for storing operation data. Those memory units 106 used for storing operation data must be cleared by the application program to prevent operation errors. Therefore, the CPU 82 delivers a control instruction to the memory controller 98 for starting the data clear module 100. In addition, the CPU 82 also delivers the memory addresses corresponding to the memory units 106 to be cleared to the address register 102. Accordingly, the data clear module 100 can select the logic value “1” or “0” to overwrite data stored in the portion of the memory units 106. As described, instead of outputting the logic value repeatedly to the data register 104, the logic value is generated by the CPU 82 and only has to be delivered to the data clear module 100 once when clearing data. Therefore, the efficiency of the CPU 82 is improved. In addition, since the CPU 82 does not need to repeatedly deliver the logic value to the data register 104, it only has to directly output the logic value to the data clear module 100 once. The bandwidth of the FSB between the CPU 82 and the north bridge circuit 84 is not consumed. In addition, if the data to be cleared includes a plurality of data bits, the memory controller 98 generally uses physical memory addresses (for example a memory address table) to access memory units 106 of the memory 90. FIG. 3 is a schematic diagram of a memory address table 107. As shown in FIG. 3, the memory address table 107 includes three kinds of fields where fields 108a, 108b, and 108n record the physical memory addresses, fields 110a, 110b, and 110n record flags which represent whether the data is an end portion (end of file, EOF), and fields 112a, 112b, 112n designate a bit length of each physical memory address recorded in fields 108. For example, if a program (an application or a driver) has to clear the data stored in a plurality of memory units 106 in the memory 90, the program first generates the memory address table 107 via the operation system of the computer system 80, and stores the memory address table 107 in a predetermined memory block of the memory 90. Then, the CPU 82 executes the program codes of the program, and thus outputs a control instruction to the memory controller 98 so as to start the data clear module 100. While being started, the data clear module 100 reads the memory address table 107 in order to distinguish exactly the physical memory addresses to be cleared. Consequently, the data clear module 100 can read a memory address ADDRESSa recorded in field 108a, and consecutively clear a plurality of data bits from the memory address ADDRESSa according to a bit length LENGTHa recorded in field 112a. In other words, the physical memory addresses corresponding to the plurality of data bits are consecutively written to the address register 102 (e.g. the data bits from ADDRESSa to ADDRESSa+(LENGTHa-1) or from ADDRESSa to ADDRESSa−(LENGTHa-1)), so that the data register 104 overwrites data stored in the memory units 106 corresponding to the physical memory addresses with the logic value (“1” or “0”). In addition, since the flag recorded in field 110a is “0” which means the data is not an end portion, the data clear module 100 keeps on reading a memory address ADDRESSb in field 108b, and clearing a plurality of data bits of a length LENGTHb according to a bit length LENGTHb recorded in field 112b. Again since the flag recorded in field 110b is “0”, the data clear module 100 continues to clear data according to the memory address table 107. After the data clear module 100 reads a memory address ADDRESSn recorded in field 108n, and clears a plurality of data bits having a bit length LENGTHn recorded in field 112n, the data clear module 100 stops reading memory addresses and clearing data bits since the flag recorded in field 110n is “1”, which means the data is an end portion. It is worth noting that in the above case the physical memory addresses are discontinuous, therefore the memory address table 107 is necessary for the data clear module 100 to clear data. If the physical memory addresses corresponding to the memory units 106 are continuous, the computer system 80 only has to provide a source memory address and the bit length of the data for the data clear module 100. The data clear module 100 can therefore consecutively clear data according to the source memory address and the bit length of the data. FIG. 4 is a schematic diagram of a computer system 120 according to a second preferred embodiment of the present invention. As shown in FIG. 4, the computer system 120 includes a CPU 122, a north bridge circuit 124, a south bridge circuit 126, a display 128, a memory 130, an input device 132, and a hard disk 134. The north bridge circuit 124 includes a memory controller 136 and a display controller 138. The memory controller 136 includes a data clear module 140, an address register 142, and a data register 144. In this embodiment, the memory 130, which comprises a plurality of memory units 150 arranged in arrays, is divided into a system memory 146 and a display memory 148. Similar to the first embodiment, the data clear module 140 can clear data bits stored in the plurality of memory units 150 whether the corresponding physical memory addresses are continuous or discontinuous. If the physical memory addresses are discontinuous, the data clear module 140 can implement the clearing operation via a memory address table. If the physical memory addresses are continuous, the data clear module 140 only requires a source memory address and a bit length of the data to be clear, for clearing the data bits stored in the memory units 150 corresponding to the physical memory addresses. It is to be noted that the data clear module 140 can also clear the memory units 150 of the display memory 148. Normally, the display controller 138 uses the display memory 148 to store operation data of 2D and 3D graphic calculations. The display memory 148 includes an image buffer zone and a Z buffer zone, where the image buffer is for storing the display data (e.g. gray scale value) of each pixel in the display 128, and the Z buffer is for storing the relative depth value of the display data in each pixel. After the display controller 138 reads the display data stored in the image buffer to drive the display 128 for displaying an image, the display controller 138 must clear data stored in the image buffer and in the Z buffer before next image is displayed. In such case, the CPU 122 will output a logic value to the data clear module 140 once, and the memory addresses of the memory units 150 corresponding to the image buffer and the Z buffer to the address register 142. Meanwhile, the data clear module 140 starts to output a predetermined logic value (“1” or “0”) to the data register 144 so that the data clear module 140 can overwrite the memory units 150 corresponding to the image buffer and the Z buffer with the predetermined logic value according to the memory addresses held in the address register 142. Since the data clear module 140 can clear data of the display memory 148 without the involvement of the CPU 122, the CPU 122 can save more resources for other programs. In addition, since the limited bandwidth of the FSB between the CPU 122 and the north bridge circuit 124 is not consumed, the computer system 120 is more efficient. Those skilled in the art will readily appreciate that numerous modifications and alterations of the device may be made without departing from the scope of the present invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.

<SOH> BACKGROUND OF INVENTION <EOH>1. Field of the Invention The present invention relates to a method and related apparatus for clearing data in a memory, and more particularly, to a method and related apparatus for clearing data in a memory without the involvement of a CPU. 2. Description of the Prior Art FIG. 1 is a schematic diagram of a conventional computer system 10 . As shown in FIG. 1 , the computer system 10 includes a CPU 12 , a north bridge circuit 14 , a south bridge circuit 16 , a display controller 18 , a display 19 , a memory 20 , a hard disk 22 , and an input device 24 . The memory 20 includes a plurality of memory units 26 arranged in arrays, i.e., each memory unit 26 corresponds to a column address and a row address. The accessing operations of the memory 20 are controlled via a memory controller 30 positioned in the north bridge circuit 14 . The memory controller 30 includes an address register 32 and a data register 34 where the address register 32 is for storing memory addresses, and the data register 34 is for storing data to be written to the memory 20 and data read from the memory 20 . For the computer system 10 , any executed programs, for example a driver or an application program, require the memory 20 for storing data. When a first application program is executed, a memory block of the memory 20 is designated for storing operation data of the first application program. While the first application program is closed, the memory block must be released so that other programs can use this memory block to store data. In addition to release the memory block, however, the first application program must clear the memory block, by for example overwriting the data stored in each memory unit 26 of the memory block with a logic value “1” or “0”. In such case, a second application program executed thereafter, can correctly access data in the same memory block. If that memory block is not cleared, errors due to misjudgment may occur when the second application program is executed. These errors may even lead to the crash of the computer system 10 . Therefore, when a program requires a certain capacity of memory units 26 in the memory 20 to store operation data, that certain capacity of memory units 26 must be overwritten with logic values “1” or “0”. For example, if the CPU 12 executes the program codes of clearing data, the CPU will output the memory addresses corresponding to the memory units 26 to be used to the address register 32 . Meanwhile, the CPU 12 will repeatedly output the logic value “1” or “0” to the data register 34 . If the capacity of the memory 20 to be used is 3 MB, the CPU 12 will output the logic values “1” to the data register 34 24 million times for clearing 24 million memory units 26 (corresponding to 3 MB capacity) in the memory 20 . It can be seen that the CPU 12 spends much time repeatedly outputting the logic value “1” or “0” to the memory 20 , thereby reducing its efficiency. In addition to reducing the efficiency of the CPU 12 , the limited bandwidth of the front-side bus (FSB) between the CPU 12 and the north bridge circuit 14 is also consumed. This also affects the total efficiency of the computer system 10 .

<SOH> SUMMARY OF INVENTION <EOH>It is therefore a primary objective of the present invention to provide a method and related apparatus of clearing data in a memory for solving the above problems. According to the claimed invention, a method of clearing data in a memory of a computer system is disclosed. The computer system includes a processor, and a memory controller electrically connected to the processor and the memory for controlling the accessing operations of the memory. The method includes the processor generating a predetermined logic value and delivering the predetermined logic value to the memory controller, and the memory controller repeatedly overwriting data stored in the plurality of memory units by the predetermined logic value. The claimed invention further includes a computer system including a processor for controlling operations of the computer system, a memory having a plurality of memory units for respectively storing a data, and a memory controller electrically connected to the processor and the memory. The memory controller includes an address register for storing a plurality of memory addresses corresponding to the plurality of memory units, a data register, and a data clear module for transmitting a predetermined logic value generated by the processor to the data register so that the predetermined logic value overwrites data stored in the plurality of memory units one by one. These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

20040326

20061017

20050310

68119.0

KIM, HONG CHONG

MEMORY CONTROLLER INCLUDING DATA CLEARING MODULE

UNDISCOUNTED

ACCEPTED

ACCEPTED

EFFICIENT BLENDING BASED ON BLENDING COMPONENT AVAILIABLITY FOR A PARTIAL BLEND DURATION

An aspect of the present invention takes advantage of the information of expected time of availability of an unavailable component to meet a desired criteria (e.g., minimize the aggregate cost of components). An intermediate product properties combination, which can be attained from an initial heel volume by mixing the available components, may be determined. The combination further permits the target product properties also to be attained from the intermediate product properties combination, while meeting various constraints and desired criteria. The flow controls of the individual components are accordingly controlled to blend the components and produce the desired product. Such features may be useful in environments such as oil refineries.

1. A method OLE_LINK1 of blending a plurality of components to produce a product having a plurality of target properties, each of said plurality of components impacting one or more of said plurality of target properties when blended, wherein a first component comprised in said plurality of components being scheduled to be available only at a time instance during blending, OLE_LINK1 said method comprising: receiving in a digital processing system data indicating said plurality of target properties, the manner in which each of said plurality of components impacts any of said plurality of target properties, an aggregate volume of said product to be produced; determining in said digital processing system an intermediate blend point at or after said time instance such that a corresponding intermediate properties combination can be attained at said intermediate blend point and said plurality of target properties can be attained from said intermediate blend point; and controlling flow rates of each of said plurality of components to attain said intermediate properties combination before said first component becomes available, and to attain said plurality of target properties from said intermediate properties combination after said first component becomes available, whereby said product of said aggregate volume is generated by blending said plurality of components. 2. The method of claim 1, wherein said determining determines said intermediate blend point to meet a desired criteria. 3. The method of claim 2, wherein said desired criteria comprises minimizing total cost of said plurality of components blended to produce said product. 4. The method of claim 1, wherein each of said plurality of components are provided for blending by a corresponding plurality of outlets, wherein each of a plurality of source controllers control the flow rate of a corresponding one of said plurality of outlets, said method further comprises: determining in said digital processing system each of a first plurality flow rates for a corresponding one of each of said plurality of components before said intermediate blend point such that said intermediate properties combination is attained for said product at said intermediate blend point; determining in said digital processing system each of a second plurality flow rates for a corresponding one of each of said plurality of components after said intermediate blend point such that said plurality of target properties are attained for said product after said intermediate blend point, wherein said controlling is performed by operating said plurality of outlets according to said first plurality of flow rates and said second plurality of flow rates. 5. The method of claim 1, wherein said determining comprises: computing using said digital processing system a plurality of ideal volumes corresponding to said plurality of components which would be blended if said first component were to be available during entire blend duration, wherein said plurality of ideal volumes includes a first ideal volume for said first component; assigning said first ideal volume to a temporary variable; searching whether one or more of said intermediate blend points are feasible with said temporary variable as volume for said first component; if one or more of said intermediate blend points are feasible, said controlling using one of said one or more intermediate blend points to control flow rates of said plurality of components; and if any of said intermediate blend points is not feasible, decreasing said temporary variable by an amount and performing said searching. 6. The method of claim 5, wherein said finding finds said one or more intermediate blend points consistent with a plurality of constraints posed by a manufacturing plant. 7. The method of claim 1, wherein said method is performed in an oil refinery. 8. A computer readable medium carrying one or more sequences of instructions for causing a computer system to support blending of a plurality of components to produce a product having a plurality of target properties, each of said plurality of components affecting one or more of said plurality of target properties when blended, a first component being scheduled to be available only at a time instance during blending, wherein said first component is comprised in said plurality of components, wherein execution of said one or more sequences of instructions by one or more processors contained in said computer system causes said one or more processors to perform the actions of: receiving data indicating said plurality of target properties, the manner in which each of said plurality of components affects any of said plurality of target properties, said time instance, an aggregate volume of said product to be produced; and determining an intermediate blend point at or after said time instance such that a corresponding intermediate properties combination can be attained at said intermediate blend point and said plurality of target properties can be attained from said intermediate blend point, wherein flow rates of each of said plurality of components are controlled to attain said intermediate properties combination before said first component becomes available, and to attain said plurality of target properties from said intermediate properties combination after said first component becomes available, whereby said product of said aggregate volume is generated by blending said plurality of components. 9. The computer readable medium of claim 8, wherein said determining determines said intermediate blend point to meet a desired criteria. 10. The computer readable medium of claim 9, wherein said desired criteria comprises minimizing total cost of said plurality of components blended to produce said product. 11. The computer readable medium of claim 8, wherein each of said plurality of components are provided for blending by a corresponding plurality of outlets, wherein each of a plurality of source controllers control the flow rate of a corresponding one of said plurality of outlets, further comprises: determining in said computer system each of a first plurality flow rates for a corresponding one of each of said plurality of components before said intermediate blend point such that said intermediate properties combination is attained for said product at said intermediate blend point; determining in said computer system each of a second plurality flow rates for a corresponding one of each of said plurality of components after said intermediate blend point such that said plurality of target properties are attained for said product after said intermediate blend point, wherein said controlling is performed by operating said plurality of outlets according to said first plurality of flow rates and said second plurality of flow rates. 12. The computer readable medium of claim 8, wherein said determining comprises: computing a plurality of ideal volumes corresponding to said plurality of components which would be blended if said first component were to be available during entire blend duration, wherein said plurality of ideal volumes includes a first ideal volume for said first component; setting a temporary variable equal to said first ideal volume; finding whether one or more of said intermediate blend points are possible with said temporary variable as volume for said first component; if one or more of said intermediate blend points are possible, using one of said one or more intermediate blend points to control flow rates of said plurality of components; and if one or more of said intermediate blend points are not possible, decreasing said temporary variable by an amount and performing said finding. 13. The computer readable medium of claim 12, wherein said finding finds said one or more intermediate blend points consistent with a plurality of constraints posed by a manufacturing plant. 14. A manufacturing plant for blending a plurality of components to produce a product having a plurality of target properties, each of said plurality of components affecting one or more of said plurality of target properties when blended, a first component being scheduled to be available only at a time instance during blending, wherein said first component is comprised in said plurality of components, said manufacturing plant comprising: a blender; a plurality of outlets, wherein each of said plurality of outlets provides a corresponding one of said plurality of components according to a corresponding flow rate for blending by said blender; a plurality of source controllers, wherein each of said plurality of source controllers controls the flow rate of a corresponding one of said plurality of outlets; and a blend controller determining the flow rate for each of said plurality of source controllers, said blend controller operable to: receive data indicating said plurality of target properties, the manner in which each of said plurality of components affects any of said plurality of target properties, said time instance, an aggregate volume of said product to be produced; determine an intermediate blend point at or after said time instance such that a corresponding intermediate properties combination can be attained at said intermediate blend point and said plurality of target properties can be attained from said intermediate blend point; and control flow rates of each of said plurality of components to attain said intermediate properties combination before said first component becomes available, and to attain said plurality of target properties from said intermediate properties combination after said first component becomes available, whereby said product of said aggregate volume is generated by blending said plurality of components.

BACKGROUND OF INVENTION 1. Field of the Invention The present invention relates to manufacturing technologies (such as oil refineries), and more specifically to a method and apparatus for blending when one or more of the components is available only for partial blend duration with components affecting several properties of the end product. 2. Related Art Manufacturing plants are generally used to produce end products by blending several components (“blended components” or “blending components”). Blending generally refers to mixing components to produce an end product. It is used in several environments such as oil refineries, including without limitation, other process industries. An end product is generally characterized by several properties. For example, petrol/gasoline has properties such as RON (Research Octane Number), MON (Motor Octane Number), RDON (Road Octane Number), RVP (Reid Vapor pressure), Benzene content, API gravity, recovery at various temperatures, and final boiling point The properties of blended components generally impact properties of the end product, and each component may impact a specific property to a different degree. Continuing with the example of above, Butane typically has a higher Octane number compared to the other blending components, for example, Butane has a Octane Number that is greater than 100, whereas the other Blending components may have a Octane number which is much less when compared to 100. Any increase of Butane in the blend will have a direct incremental impact on the Octane Number of the Blended product. However, Butane is also lower in Reid Vapor pressure compared to the other blending components, for example, RVP of Butane is in the range of 10 to 12 Kpa. When the Butane content in the Blend is increased then this would have a decremental impact on the Reid vapor pressure of the Blended product. Similarly, Light Reformats would have a high benzene content and will play a key role in increasing the Benzene content of the Blended product. From the above, it may be appreciated that one skilled in the related art may conventionally determine the ratios of quantities of each component that may be used to generate an end product having desired (range) values of various properties. Accordingly, a manufacturing plant may blend the components in such ratios to produce an end product having desired properties. Generally, executing such a conventional process has certain limitation such as, for example, timely availability of the blending components. Further, it is undesirable to wait until such components are available since production delays usually translate to economic loss. For convenience, it is assumed that only one component is unavailable and is referred to below as “unavailable component”. One another conventional process addresses such production delays by continuing the blending operation using available components at the time of blending. During execution of such a conventional process, ratio (flow-rate ratio or volumetric ratio, etc.) of blending is computed without taking into account expected time of availability of the unavailable component. It may therefore be apparent that such conventional approaches do not address the issues pertaining to meeting at least some of desired objectives. For example, one objective could be to minimize the aggregate cost of components, but the conventional approach may use a relatively more expensive component in a substantial quantity (while desired properties could have been attained using less expensive components), thereby leading to an increase in the cost of aggregate components used. Accordingly, there is a need in the related art to develop techniques, which enable desired objectives to be met while blending, when one or more of the components is available only for partial blend duration with components affecting several properties of the end product. SUMMARY OF INVENTION An aspect of the present invention enables efficient blending of components to produce a product having target (desired) properties, when each component impacts potentially multiple target properties when blended and when a first component is scheduled to be available only at a known time instance during blending. In an embodiment, a digital processing system receives data indicating the target properties, the manner in which each component impacts each target property, and an aggregate volume of the product to be produced. The digital processing system may determine an intermediate blend point at or after the time instance such that a corresponding intermediate properties combination can be attained at the intermediate blend point and the target properties can be attained from the intermediate blend point. The flow rate of each component is controlled to attain the intermediate properties combination before the intermediate blend point, and to attain the target properties from the intermediate properties combination after the intermediate blend point. Several advantages may be attained by using such an approach. For example, the intermediate blend point may be computed to meet a desired criteria using various well-known approaches. In one embodiment, the criteria is to minimize the total cost of the components blended to produce the product. However, the desired criteria can be based on any considerations suitable for the specific situation according to various aspects of the present invention. In an implementation, each component is provided for blending by corresponding outlets, and each source controller controls the flow rate of the corresponding outlet. In such an embodiment, a digital processing system may determine first flow rates of respective components before the intermediate blend point such that said intermediate properties combination is attained for the product at the intermediate time instance, and second flow rates of respective components after the intermediate blend point. The outlets are operated according to the first flow rates before the intermediate time point and according to the second flow rates after the intermediate time point to produce the product with the target properties. The intermediate blend point may be determined using one of several known approaches. In an embodiment, a digital processing system determines the ideal volumes of components which would be blended if all components were to be available during entire blend duration, wherein the ideal volumes include a first ideal volume for the first (i.e., unavailable) component. The intermediate blend points are sought to be determined attempting to use the first ideal volume for the first component. If no such intermediate blend point is determined to be feasible, the volume for the first component is decremented, and feasible intermediate blend points are sought to be determined with the decremented volume for the first component. Further features and advantages of the invention, as well as the structure and operation of various embodiments of the invention, are described in detail below with reference to the accompanying drawings. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number. BRIEF DESCRIPTION OF DRAWINGS The present invention may be described with reference to the accompanying drawings briefly described below. FIG. (Fig.) 1 is a block diagram depicting a typical environment to implement various aspects of the present invention. FIG. 2 is a table illustrating desired range of values for the properties to be maintained in the blend header during the course of blending and for the end product at the end of the blend operation in an illustrative example scenario. FIG. 3 is a table illustrating the manner in which each component affects each of the properties of the product in the illustrative example. FIG. 4 is a table illustrating the flow constraints and volume constraints imposed by the equipment while blending the components in the illustrative example. FIG. 5 is a flowchart illustrating the manner in which a product is blended according to an aspect of the present invention when one of the components is available only for a partial blend duration. FIG. 6 is a graph containing two lines respectively depicting the value of property 1 (prop 1) at various volumes of blend during blending according to an aspect of the present invention and a prior approach. FIG. 7 is a table illustrating the range of intermediate property values computed in an embodiment for the illustrative example scenario. FIG. 8 is a table illustrating the volumes of components consumed before and after arrival of a (unavailable) component in one prior approach. FIG. 9 is a table illustrating the volumes of components consumed before and after arrival of a (unavailable) component in an embodiment of the invention. FIG. 10 is a table containing blend properties in the blender before and after arrival of the (unavailable) component, illustrating some more example constraints, which are sought to be satisfied in the illustrative example. FIG. 11 is shown containing a table illustrating the relative total costs and blended volumes for the components in the case of a prior approach and an aspect of the present invention for the illustrative example. FIG. 12 is a flow chart illustrating the manner in which the intermediate properties combination may be determined in an embodiment of the present invention. FIG. 13 is a block diagram illustrating the manner in which various aspects of the present invention can be implemented substantially in the form of software instructions. DETAILED DESCRIPTION 1. Overview According to an aspect of the present invention, intermediate blend points with corresponding intermediate properties at or after the time instance at which an unavailable component is expected to be available, are computed. The intermediate blend points are computed such that the corresponding intermediate properties can be attained at the corresponding time instances, as well as the target properties can eventually be attained from the intermediate product properties (while satisfying various constraints) at the end of the blend operation. The intermediate blend points may be determined based on the manner in which each component affects each target (desired) property, a time instance at which the unavailable component is expected to be available, and an aggregate volume of the product to be produced. Various mathematical approaches can be used to determine the intermediate blend points. Several aspects of the invention are described below with reference to examples for illustration. It should be understood that numerous specific example details, relationships, and methods are set forth to provide a full understanding of the invention. One skilled in the relevant art, however, will readily recognize that the invention can be practiced without one or more of the specific details, or with other methods, etc. In other instances, well-known structures or operations are not shown in detail to avoid obscuring the invention. 2. Example Environment FIG. 1 is a block diagram illustrating the details of an example environment in which various aspects of the present invention can be implemented. The environment is assumed to represent an oil refinery merely for illustration. However, various aspects of the present invention can be used in other environments in which there is an overlap of properties (of a product sought to be produced) that are affected by the components in blending. Merely for illustration, the block diagram is shown associated with an example in which five components are blended to produce a desired product. In addition, it should be understood that only representative example components are shown in the diagram so as not to obscure various features of the present invention. However, it will be apparent to one skilled in the relevant arts that environments may contain several other (both in number and type) components, without departing from the scope and spirit of various aspects of the present invention. The block diagram is shown containing blend controller 110, components ratio controller 120, components source controller 130-1 through 130-5, component outlets 140-1 through 140-5, components blender 160, product flow meter 170, product outlet 180, blend property analyzer 185, product storage 190, and level determination block 195. Each block is described below in detail. Components ratio controller 120 receives from blend controller 110 the ratios (e.g., in the form of volumes) in which the components are to be blended, and configures (programs) component source controllers 130-1 through 130-5 accordingly. Component source controllers 130-1 through 130-5 are configured to adjust and further control the flow rates of respective component outlets 140-1 through 140-5. Component outlets 140-1 through 140-5 respectively permit corresponding exemplary five components to flow to component blender 160. Component blender 160 blends the received components, and channels the resulting product, to product storage 190 via product flow meter 170 and product outlet 180. Product flow meter 170 displays the volume of flow of the blended product by appropriate configuration of product outlet 180. Blend property analyzer 185 typically analyzes the properties of product being transferred from components blender 160 to products storage 190 to determine the properties of the product produced by blending. The results are forwarded to blend controller 110. Level determination block 195 determines the present level of the product in product storage 190, and forwards the results to blend controller 110. Components ratio controller 120, components source controller 130-1 through 130-5, components Outlets 140-1 through 140-5, components blender 160, product flow meter 170, blend property analyzer 185, product storage 190, and level determination block 195 may be implemented in a known way. Blend controller 110 computes the ratios at which the components may desirably be blended at various time durations of the blending process. In one embodiment, the volumetric ratios for blending are computed first, and the volumetric ratios are then used to compute the corresponding flow ratios. The ratios may be computed while taking into account the time instances at which the corresponding components may become available and meeting any desired criteria (e.g., minimizing cost of components). The inputs used for such computation are logically represented by “A” in FIG. 1. The manner in which the ratios may be computed according to various aspects of the present invention is described below in further detail with reference to an example applicable to scenario. 3. Example Requirements FIG. 2 includes a table illustrating the properties of a product sought to be produced. The table is shown containing three columns 201-203, with column 201 indicating the property that is subject of corresponding row 221-225, column 202 indicating a minimum and a maximum value for each property of the blend during blend and column 203 indicating a minimum and a maximum value for each property of product at the end of the blend. The properties of the columns may correspond to some of those noted in the background section in the context of oil refineries. Each row is described below in further detail. In row 221, prop1 is shown to have a minimum value of 80 and maximum value of 95 during blend (i.e., within components blender 160, when being mixed). This row also indicates that the product sought to be produced needs to have a value for Prop 1 between 88 and 89, at the end of blend (as shown by point “D” of FIG. 6 described in sections below). Thus, the values in column 201 indicate the target properties for the product sought to be produced. It should be understood that the values shown in column 202 of FIG. 2 represent example constraints while blending to produce the desired product. There can be other constraints as well. For example, each source controller 130-1 through 130-5 may be able to hold only a corresponding amount/volume of the component, each outlet 140-1 through 140-5 (described below with reference to FIG. 4) and 180 may have a corresponding maximum flow rate. All such constraints may need to be satisfied while producing a product of desired target qualities. The description is continued with respect to the manner in which each component may affect a specific quality of the product. FIG. 3 contains a table illustrating the components that may be blended to produce a desired product, and the manner in which each component affects the specific properties of the product. The table is shown containing 9 columns with 301 indicating the specific component that is subject of corresponding row 321-325, columns 302 through 306 respectively indicating how the corresponding property is affected by the subject component, columns 307 and 308 indicating minimum and maximum ratio of the subject component that may be allowed in the blend, and column 309 indicates the cost per unit of the subject component. Row 321 indicates properties of component C1 and how this component when blended affects each of the specific property of the product. The row indicates that adding one unit volume of component 1 affects properties 1-5 by 110, 100, 20, 680, and 3 respectively. Row 321 also indicates that the blend could contain between 0% and 100% of computed volume of this component, and the cost per unit of this component is 135. For example, when a blend contains only components C1 and C2 in equal proportion, value of prop1 is impacted linearly by volume of both C1 and C2 and this value is computed as 50/100*110+50/100*88. Rows 322 through 325 contains similar details for components C2-C5 respectively. Row 326 contains property values of initial volume (heel) of the product in product storage, at the start of the blend. The row indicates that prop1 of heel (Point A of FIG. 6) is 80. It also indicates that heel has a value of 70 for prop2, 40 for prop3, 700 for prop4 and 2 for prop5. The description is continued with respect to additional constraints in producing such a product. FIG. 4 contains a table illustrating some constraints posed by the equipments used in a manufacturing plant. The table is shown containing 5 columns with 401 indicating the specific component source posing some constraints that is subject of corresponding rows 421-425. Columns 402 and 403 respectively indicate minimum and maximum flow constraints imposed by outlets 140-1 through 140-4. Columns 404 and 405 indicate any minimum and maximum volumes of the subject component source. The maximum volume may be set by the storage capacity of source controllers and/or timely availability of the components. Row 421 indicates that source controller 130-1 used to supply C1 (130-1 of FIG. 1) allows a minimum value of 0 units and a maximum value of 450 units to flow through its outlet (140-1 of FIG. 1). The row also indicates that this equipment could store between 0 and 15000 units of component C1. Rows 422 through 425 indicates similar constraints posed by other equipments used to supply components C2 to C5. The description is continued with respect to the manner in which various aspects of the present invention enable a product to be produced within requirements such as those noted above. Merely for convenience, it is assumed that there is one unavailable component (C5) for blend and it becomes available at a specific time instance from start of blend. 4. Method FIG. 5 is a flow chart illustrating the manner in which a product may be produced according to various aspects of the present invention. The method is described with reference to FIGS. 1-4 merely for illustration. However, the method can be implemented in other environments as well. The method begins in step 501 and control immediately passes to step 510. In step 510, blend controller 110 receives data indicating the target properties of the end product sought to be produced, how each component affects each of the properties, the aggregate volume of the product to be produced, a time instance at which an unavailable component may become available. Some or all of the parameters may be received based on operator inputs and values generated by other digital processing systems. In step 520, blend controller 110 determines intermediate blend points at or after the time instance such that the intermediate properties can be attained at each corresponding intermediate blend point and the target properties can be attained from the intermediate blend point while satisfying any other constraints. Such a determination can be performed using one of several approaches. An example approach is described in a section below in further detail. In step 530, blend controller 110 selects one of the intermediate blend points, which meets a desired set of criteria. In one embodiment described below, the total cost of components is sought to be minimized. However, other criteria may also be used without departing from the scope and spirit of various aspects of the present invention. In step 540, the available components are blended until the selected intermediate blend point to attain a blend having a corresponding intermediate quality metrics. In general, the ratios (or flow-rates) of components need to be determined to attain the intermediate quality metrics and the corresponding values are used to control source controllers 130-1 through 130-5 via components ratio controller 120. In Step 550, potentially all components are blended from the selected intermediate blend point (i.e., when the unavailable component becomes available) to attain a blend having the target properties. Again, the ratios of components need to be determined to attain the target properties (from the intermediate properties), and the components mixed accordingly. The flow chart ends in step 599. Due to the computations of step 520, the target properties may be attained while meeting a desired set of criteria. The features of the flow chart may be appreciated by comparison with an approach that does not use the information on expected time of availability of an unavailable component. 5. Comparison With a Conventional Approach FIG. 6 is a graph illustrating the advantages offered by various aspects of the present invention in comparison with a prior approach. The graph corresponds to one of the properties (Prop1) noted in the description above. Similarly, other properties also may be addressed in according to aspects of the present technique. The graph is shown with blend quantity (i.e., the amount of product produced by blending) on X-axis and the present property value on Y-axis. The X-axis may also be viewed as representing lapse of time during blending and thus each point of X-axis is described as a time instance. For illustration, it is assumed that component C5 is expected to arrive at a time instance corresponding to 650. Time instance corresponding to 699 represents an expected end time instance for blending assuming that the aggregate flow rate (1500 in example noted above) is completely used during the entire blend duration. Two lines 610 and 621 are shown, which are described below in further detail. Broken line 610 corresponds to a prior approach, which does not take advantage of such time of availability. As noted above in the background section, the prior approach may use blend ratios, which are computed without regard to the expected time of availability. The computed ratios are used up to time instance 650 and the corresponding present quality is represented by segment 611. The blend ratios are recomputed at time instance 650 and these newly computed ratios are used in segment 612. Solid line 621 corresponds to an approach, which takes advantage of the information on the time of availability of component C5 in an embodiment of the present invention. Thus, the blend ratios in segment 621 are computed by determining an intermediate blend point (corresponding to time instance 650) having an associated intermediate blend properties which satisfy two conditions: (1) the intermediate blend properties are attainable in segment 621 (i.e., from start of blending to time instance 650) within the remaining constraints; and (2) the target product properties are attainable in segment 622 (between time instance 650 and the end of blend point 699). If multiple such properties are possible, an intermediate blend point, which meets a desired (set of) criteria (e.g., minimising cost) may be selected. Due to the use of such approach described associated with solid line 621, the desired product may be produced meeting a desired criteria and also meeting other constraints as described below with reference to the tables of FIGS. 7 through 12. 6. Tables FIG. 7 contains a table illustrating a range of intermediate blend properties at time instance 650 (of FIG. 6), which permit the target properties to be eventually achieved by time instance D (of FIG. 6) while minimizing the overall cost of components. The range may be determined using various mathematical models such as Linear Programming Model, as described in sections below. The specific intermediate blend property is determined taking into account the time duration after which the components are scheduled to become available or unavailable, starting quality of the product in the tank, constraints (property in the blend header, at the end of the blend, flow and volume), components qualities and the time duration that would be left after arrival of the component till the end of the blend. The intermediate values may be determined using techniques such as standard Mathematical models, which use Linear programming principles. The table of FIG. 7 is shown containing three columns 701-703, with column 701 indicating the specific property that is subject of corresponding row 721-725, column 702 indicating a lower limit of intermediate blend property, and column 703 indicating an upper limit of the intermediate blend property. Thus, row 721 indicates that the low and high values for property prop1 are respectively 83.4125 and 83.9625. As may be noted, solid line 621 of FIG. 6 has a value of 83.4615 at time instance 650, consistent with the requirement of row 721. The remaining rows are described similarly. FIG. 8 contains a table illustrating computed volume of components used, based on the prior approach of broken line 610 of FIG. 6. The table is shown containing 4 columns 801-804, with 801 indicating the specific component name of corresponding row 821-825. Column 802 contains volume of components used, until time instance (i.e., 650 in the example of FIG. 6) when an unavailable component becomes available. Column 803 contains computed volume of each component used in blend during partial blend duration after (i.e., between 650 and point D of FIG. 6) unavailable component becomes available. Column 804 indicates total volume of each component used during entire blend duration in the prior approach. Row 825 indicates that 0 units of comp 5 are consumed in the entry corresponding to column 802 since comp 5 is unavailable in the corresponding duration. The row further indicates that 1540 units of comp 5 are consumed thereafter in the remaining blend duration. Rows 821-824 is described similarly. Row 826 indicates that a total of 9000 units are blended before the unavailable component (Comp 5) becomes available, and 11000 units are blended thereafter. The X-axis values in broken line 610 of FIG. 6 are consistent with these numbers. The description is continued to provide a comparison of the corresponding volumes of components used in an embodiment of the present invention. FIG. 9 contains a table illustrating the computed volume of components used, in an embodiment of the present invention. The table is shown containing 4 columns 901-904 and six rows 921-926. The rows and columns are described below. Column 901 indicates the specific component, which is the subject of corresponding row 921-925. Column 902 contains volume of components used in blend until time instance when an unavailable component becomes available. As may be readily appreciated, the volumes may be computed in step 540. Column 903 contains volume of components used in blend during partial blend duration after the unavailable component becomes available. The values of column 903 may be computed in step 550. Column 904 indicates total volume of each component used during entire blend duration. Row 925 indicates that 0 units of Comp 5 are consumed in the entry corresponding to column 902 since the component is unavailable in the corresponding duration. The row further indicates that 2800 units of Comp 5 are used in the remaining blend duration. As may be appreciated more units (2800 in FIG. 9 versus 1540 in FIG. 8) of Comp 5 are consumed in the embodiment according to the present invention compared to the prior embodiment described in FIG. 8. The use of more units leads to lesser total aggregate cost since Comp 5 is shown to be a cheaper (assumed to be the desired criteria) component than Comp 1 (which is used more in the described prior approach) in FIG. 3. Such an optimization is achieved as various aspects of the present invention take advantage of the information on expected time of availability of the unavailable component(s). It may be appreciated that the various additional constraints may need to be satisfied while meeting the desired criteria. The blend properties noted above with respect to column 202 of FIG. 2 may also be satisfied, as described below with respect to FIG. 10. FIG. 10 is a table containing the properties maintained in blender 160 before and after the unavailable component becomes available. The table illustrates that the properties (resulting due to mixing of components as per volumes depicted in FIG. 9) in the blender are within the ranges specified by column 202 of FIG. 2. The table of FIG. 10 is shown containing three columns 1001-1003 and rows 1021-1025. Column 1001 indicates the specific property that is subject of corresponding row 1021-1025, column 1002 indicates value for properties until time instance when an unavailable component becomes available, and column 1003 indicates value of properties after this time. Row 1021 indicates that prop1 has a value of 85.00 before the unavailable component (Comp 5) becomes available, and a value of 93.36 thereafter. The two values are consistent with the blend property constraint noted in row 221, column 202 of FIG. 2, as desired. The remaining rows 1022-1024 are described similarly. The description is continued with reference to a summary of comparison of various results due to the use of the prior approach of broken line 610 and the illustrative embodiment of the present invention. FIG. 11 is a table containing differences in values of various parameters such as cost, ratio and volume of each component consumed, between the prior approach and present invention thereby illustrating the advantages attained in the illustrative example above. The table is shown containing 7 columns 1101-1107, with 1101 indicating the specific component that is subject of corresponding row 1121-1125. Columns 1102 and 1103 respectively contain the same values as 804 and 904, and the description is not repeated in the interest of conciseness. Columns 1104 and 1105 respectively are shown containing values for ratios of components used in corresponding approaches. Each ratio is generally computed by dividing the corresponding volume by the aggregate blend volume in the corresponding duration. Columns 1106 and 1107 contain the aggregate cost due to the corresponding component. Row 1125 (unavailable component) indicates that a total of 1540 units of Comp 5 are used in the example prior approach leading to a corresponding cost of 7.7 (computed according to the table of FIG. 3). On the other hand, in the illustrative embodiment in accordance with the present invention, a total of 2800 units of Comp 5 are used leading to a cost of 14. The remaining rows 1121-1124 are similarly described. Row 1126 is shown containing the total cost for producing same volume of a product using the prior approach and present invention. The cost of production using the prior approach is 90.329 and that based on present invention is 88.550. The lower cost is attained since various aspects of the present invention take advantage of available information on any expected time of availability of unavailable components. It may be appreciated that the above tables are described assuming that the optimal intermediate product properties are determined. Various mathematical/heuristics based approaches can be used to determine such properties. An example approach to determine the optimal intermediate product properties is described below in further detail. 7. Determining Intermediate Product Properties FIG. 12 is a flow chart illustrating the manner in which the intermediate product properties (corresponding to point 650) may be determined according to an aspect of the present invention. The flowchart begins in step 1201, in which control immediately passes to step 1210. In step 1210, blend controller 110 determines ideal component volumes to blend assuming all components (including C5 of the illustrative example) are available. In other words, the component volumes are determined considering the desired criteria and various constraints, but assuming that all the components are available. It may be appreciated that such a computation indicates the optimal volume/amount (quantity in general) of the unavailable component (C5) that should be ideally used to achieve the desired criteria. Accordingly, in step 1220, blend controller 110 sets a variable temp to equal the volume of the unavailable product. In step 1230, blend controller 110 determines whether at least one intermediate blend properties combination meeting all constraints is possible assuming temp amount of unavailable component will be blended after availability of the unavailable component. In other words, each such intermediate blend properties combination is attainable from the initial heel volume, and the target product properties is attainable from the intermediate blend properties, while meeting various constraints. In step 1240, blend controller 110 determines whether at least one such combination exists. Control passes to step 1250 if such a combination exists, otherwise to step 1270. In step 1250, blend controller 110 determines whether at least one combination meets the desired criteria. In one embodiment, the desired criteria is set to merely minimize the cost. In such a case, the combination providing the least cost (computed according to table 3) is deemed to meet the desired criteria. Alternatively, the desired criteria may contain a threshold for a total cost, and a combination may be deemed to meet the desired criteria only if the corresponding total cost is less than or equal to such a threshold. Control passes to step 1260 if the desired criteria is not met or if additional search is desirable for whatever reasons. Otherwise, since the desired intermediate properties combination is found, control passes to step 1299, in which the method ends. In step 1260, blend controller 110 may decrease variable temp by delta, and control passes to step 1270. Delta may be chosen to be any positive integer, and can vary to permit various search approaches, as is well known in the relevant arts. In step 1270, control passes to step 1230 if temp is greater than 0, or else to step 1280. The search for intermediate blend properties continues in step 1230 with the new value of temp. In step 1280, blend controller 110 may relax constraints or desired criteria. For example, the threshold for the total cost (noted above in step 1250) may be increased. Control then passes to step 1220 to continue the search. It should be understood that the approaches of above may be used by blend controller 110 to determine various intermediate product properties combinations first, and select one of the combinations without terminating the search in step 1260 noted above. It should be understood that the approach(es) of above can be extended to situations in which an unavailable component (C5 above) becomes available earlier or later than an expected time of arrival (650 of FIG. 6). In such a situations, the computations of above may be performed again treating the presently available volume in the storage 190 as heel. The above approach can also be extended to situations when multiple components may not be available at the start of the blend and information regarding expected time of availability of these components is known. In such a situation, the concept could be extended to determine various combinations of intermediate blend points and intermediate blend properties until the best combination that meets example requirements is determined. Once the desired optimal combination is determined, the product blending may be continued accordingly as described above with reference to FIG. 6. As a result, various aspects of the present invention permit that any desired criteria can be potentially met if one of the components is available only for partial blend duration with components affecting several properties of the end product. It should be understood that blend controller 110 can be implemented substantially in the form of a digital controller system controlled by software instructions as described below in further detail. 8. Software-driven Implementation FIG. 13 is a block diagram illustrating the details of digital processing system 1300 implemented substantially in the form of software in an embodiment of the present invention. System 1300 may correspond to a portion of blend controller 110. System 1300 may contain one or more processors such as central processing unit (CPU) 1310, random access memory (RAM) 1320, secondary memory 1330, graphics controller 1360, display unit 1370, network interface 1380, and input interface 1390. All the components except display unit 1370 may communicate with each other over communication path 1350, which may contain several buses as is well known in the relevant arts. The components of FIG. 13 are described below in further detail. CPU 1310 may execute instructions stored in RAM 1320 to provide several features of the present invention. CPU 1310 may contain multiple processing units, with each processing unit potentially being designed for a specific task. Alternatively, CPU 1310 may contain only a single general purpose processing unit. RAM 1320 may receive instructions from secondary memory 1330 using communication path 1350. The instructions may determine the intermediate property points and the flow rates before and after the selected intermediate property point, and configure components ratio controller 120 accordingly. Graphics controller 1360 generates display signals (e.g., in RGB format) to display unit 1370 based on data/instructions received from CPU 1310. Display unit 1370 contains a display screen to display the images defined by the display signals. Input interface 1390 may correspond to a key-board and/or mouse. Graphics controller 1360 and input interface 1390 may enable an user to indicate information related to components availability, initial heel volume, etc. Secondary memory 1330 may contain hard drive 1335, flash memory 1336 and removable storage drive 1337. Secondary memory 1330 may store the data and software instructions (e.g., methods instantiated by each of client system), which enable system 1300 to provide several features in accordance with the present invention. Some or all of the data and instructions may be provided on removable storage unit 1340, and the data and instructions may be read and provided by removable storage drive 1337 to CPU 1310. Floppy drive, magnetic tape drive, CD-ROM drive, DVD Drive, Flash memory, removable memory chip (PCMCIA Card, EPROM) are examples of such removable storage drive 1337. Removable storage unit 1340 may be implemented using medium and storage format compatible with removable storage drive 1337 such that removable storage drive 1337 can read the data and instructions. Thus, removable storage unit 1340 includes a computer readable storage medium having stored therein computer software and/or data. In this document, the term “computer program product” is used to generally refer to removable storage unit 1340 or hard disk installed in hard drive 1335. These computer program products are means for providing software to system 1300. CPU 1310 may retrieve the software instructions, and execute the instructions to provide various features of the present invention as described above. 9. Conclusion While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of the present invention should not be limited by any of the above described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

<SOH> BACKGROUND OF INVENTION <EOH>1. Field of the Invention The present invention relates to manufacturing technologies (such as oil refineries), and more specifically to a method and apparatus for blending when one or more of the components is available only for partial blend duration with components affecting several properties of the end product. 2. Related Art Manufacturing plants are generally used to produce end products by blending several components (“blended components” or “blending components”). Blending generally refers to mixing components to produce an end product. It is used in several environments such as oil refineries, including without limitation, other process industries. An end product is generally characterized by several properties. For example, petrol/gasoline has properties such as RON (Research Octane Number), MON (Motor Octane Number), RDON (Road Octane Number), RVP (Reid Vapor pressure), Benzene content, API gravity, recovery at various temperatures, and final boiling point The properties of blended components generally impact properties of the end product, and each component may impact a specific property to a different degree. Continuing with the example of above, Butane typically has a higher Octane number compared to the other blending components, for example, Butane has a Octane Number that is greater than 100, whereas the other Blending components may have a Octane number which is much less when compared to 100. Any increase of Butane in the blend will have a direct incremental impact on the Octane Number of the Blended product. However, Butane is also lower in Reid Vapor pressure compared to the other blending components, for example, RVP of Butane is in the range of 10 to 12 Kpa. When the Butane content in the Blend is increased then this would have a decremental impact on the Reid vapor pressure of the Blended product. Similarly, Light Reformats would have a high benzene content and will play a key role in increasing the Benzene content of the Blended product. From the above, it may be appreciated that one skilled in the related art may conventionally determine the ratios of quantities of each component that may be used to generate an end product having desired (range) values of various properties. Accordingly, a manufacturing plant may blend the components in such ratios to produce an end product having desired properties. Generally, executing such a conventional process has certain limitation such as, for example, timely availability of the blending components. Further, it is undesirable to wait until such components are available since production delays usually translate to economic loss. For convenience, it is assumed that only one component is unavailable and is referred to below as “unavailable component”. One another conventional process addresses such production delays by continuing the blending operation using available components at the time of blending. During execution of such a conventional process, ratio (flow-rate ratio or volumetric ratio, etc.) of blending is computed without taking into account expected time of availability of the unavailable component. It may therefore be apparent that such conventional approaches do not address the issues pertaining to meeting at least some of desired objectives. For example, one objective could be to minimize the aggregate cost of components, but the conventional approach may use a relatively more expensive component in a substantial quantity (while desired properties could have been attained using less expensive components), thereby leading to an increase in the cost of aggregate components used. Accordingly, there is a need in the related art to develop techniques, which enable desired objectives to be met while blending, when one or more of the components is available only for partial blend duration with components affecting several properties of the end product.

<SOH> SUMMARY OF INVENTION <EOH>An aspect of the present invention enables efficient blending of components to produce a product having target (desired) properties, when each component impacts potentially multiple target properties when blended and when a first component is scheduled to be available only at a known time instance during blending. In an embodiment, a digital processing system receives data indicating the target properties, the manner in which each component impacts each target property, and an aggregate volume of the product to be produced. The digital processing system may determine an intermediate blend point at or after the time instance such that a corresponding intermediate properties combination can be attained at the intermediate blend point and the target properties can be attained from the intermediate blend point. The flow rate of each component is controlled to attain the intermediate properties combination before the intermediate blend point, and to attain the target properties from the intermediate properties combination after the intermediate blend point. Several advantages may be attained by using such an approach. For example, the intermediate blend point may be computed to meet a desired criteria using various well-known approaches. In one embodiment, the criteria is to minimize the total cost of the components blended to produce the product. However, the desired criteria can be based on any considerations suitable for the specific situation according to various aspects of the present invention. In an implementation, each component is provided for blending by corresponding outlets, and each source controller controls the flow rate of the corresponding outlet. In such an embodiment, a digital processing system may determine first flow rates of respective components before the intermediate blend point such that said intermediate properties combination is attained for the product at the intermediate time instance, and second flow rates of respective components after the intermediate blend point. The outlets are operated according to the first flow rates before the intermediate time point and according to the second flow rates after the intermediate time point to produce the product with the target properties. The intermediate blend point may be determined using one of several known approaches. In an embodiment, a digital processing system determines the ideal volumes of components which would be blended if all components were to be available during entire blend duration, wherein the ideal volumes include a first ideal volume for the first (i.e., unavailable) component. The intermediate blend points are sought to be determined attempting to use the first ideal volume for the first component. If no such intermediate blend point is determined to be feasible, the volume for the first component is decremented, and feasible intermediate blend points are sought to be determined with the decremented volume for the first component. Further features and advantages of the invention, as well as the structure and operation of various embodiments of the invention, are described in detail below with reference to the accompanying drawings. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number.

20040330

20100223

20051013

83670.0

ORTIZ RODRIGUEZ, CARLOS R

EFFICIENT BLENDING BASED ON BLENDING COMPONENT AVAILIABLITY FOR A PARTIAL BLEND DURATION

UNDISCOUNTED

ACCEPTED

ACCEPTED

System and Method to Seal by Bringing the Wall of a Wellbore into Sealing Contact with a Tubing

The invention is a system and method used to seal between an open wellbore and a tubing by bringing the wellbore wall inwardly so as to enable sections of earth from the wellbore wall to create the required seal against the tubing. The earth sections that make up the seal can be created by collapsing the relevant parts of the wellbore wall inwardly or by causing the relevant parts of the wellbore wall to swell inwardly.

1. A method to seal between a subterranean wellbore wall and an interior tubing, comprising bringing the wall inwardly towards the tubing. 2. The method of claim 1, wherein the bringing step comprises bringing the wall into sealing contact with the tubing. 3. The method of claim 1, wherein the bringing step comprises mechanically unloading a section of the wellbore. 4. The method of claim 3, wherein the mechanically unloading step comprises scraping a portion of the wellbore wall. 5. The method of claim 4, wherein the mechanically unloading step comprises collecting the portions to create the seal. 6. The method of claim 1, wherein the bringing step comprises hydraulically unloading a section of the wellbore. 7. The method of claim 6, wherein the hydraulically unloading step comprises providing a fluid stream at the wellbore wall with enough force to dislodge portions of the wellbore wall. 8. The method of claim 7, wherein the hydraulically unloading step comprises collecting the portions to create the seal. 9. The method of claim 6, wherein the hydraulically unloading step comprises creating a suction area proximate the wellbore wall with enough force to dislodge portions of the wellbore wall. 10. The method of claim 9, wherein the hydraulically unloading step comprises collecting the portions to create the seal. 11. The method of claim 1, wherein the bringing step comprises explosively unloading a section of the wellbore. 12. The method of claim 11, wherein the explosively unloading step comprises creating an explosion towards the wellbore wall to dislodge portions of the wellbore wall. 13. The method of claim 12, wherein the explosively unloading step comprises collecting the portions to create the seal. 14. The method of claim 1, wherein the bringing step comprises swelling a portion of the wellbore wall. 15. The method of claim 14, wherein the swelling step comprises distributing a chemical on the wellbore wall. 16. A method to seal between a subterranean wellbore wall and an interior tubing, comprising setting two packers against the wall and bringing the wall between the two packers inwardly towards the tubing. 17. The method of claim 16, wherein the bringing step comprises bringing the wall into sealing contact with the tubing. 18. The method of claim 16, wherein the bringing step comprises creating a suction area proximate the wellbore wall between the two packers with enough force to dislodge portions of the wellbore wall between the two packers. 19. A system for sealing between a subterranean wellbore wall and an interior tubing, comprising a sealing unit adapted to bring the wall inwardly towards the tubing. 20. The system of claim 19, wherein the sealing unit is adapted to bring the wall into sealing contact with the tubing. 21. The system of claim 19, wherein the sealing unit comprises at least one scrape arm to scrape a portion of the wellbore wall. 22. The system of claim 21, wherein the sealing unit comprises a holder to collect the portions to create the seal. 23. The system of claim 19, wherein the sealing unit comprises a pressurized fluid source and at least one nozzle, wherein the nozzle directs fluid from the source at the wellbore wall with enough force to dislodge portions of the wellbore wall. 24. The system of claim 23, wherein the sealing unit comprises a holder to collect the portions to create the seal. 25. The system of claim 19, wherein the sealing unit comprises a suction source and at least one port on the tubing, wherein the port provides fluid communication between the source and the wellbore wall and a suction area is created proximate the wellbore wall with enough force to dislodge portions of the wellbore wall. 26. The system of claim 25, wherein the sealing unit comprises a holder to collect the portions to create the seal. 27. The system of claim 19, wherein the sealing unit comprises at least one explosive, wherein the explosive creates an explosion towards the wellbore wall to dislodge portions of the wellbore wall. 28. The system of claim 27, wherein the sealing unit comprises a holder to collect the portions to create the seal. 29. The system of claim 19, wherein the sealing unit comprises a chemical source and at least one nozzle, wherein the nozzle distributes chemical from the source on the wellbore wall wellbore wall towards the tubing.

BACKGROUND OF INVENTION The invention generally relates to a system and method to seal by bringing the wall of a subterranean wellbore into sealing contact with an interior tubing. More specifically, the invention relates to a sealing system that causes the wall of a wellbore to collapse or swell and thereby provide a seal against a tubing located within the wellbore. Sealing systems, such as packers or anchors, are commonly used in the oilfield. Packers, for instance, are used to seal the annular space between a tubing string and a surface exterior to the tubing string, such as a casing or an open wellbore. Commonly, packers are actuated by hydraulic pressure transmitted either through the tubing bore, annulus, or a control line. Other packers are actuated via an electric line deployed from the surface of the wellbore. The majority of packers are constructed so that when actuated they provide a seal in a substantially circular geometry. However, in an open wellbore, packers are required to seal in a geometry that is typically not substantially circular. Thus, there is a continuing need to address one or more of the problems stated above. SUMMARY OF INVENTION The invention is a system and method used to seal between an open wellbore and a tubing by bringing the wellbore wall inwardly so as to enable sections of earth from the wellbore wall to create the required seal against the tubing. The earth sections that make up the seal can be created by collapsing the relevant parts of the wellbore wall inwardly or by causing the relevant parts of the wellbore wall to swell inwardly. Advantages and other features of the invention will become apparent from the following drawing, description and claims. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an illustration of a prior art wellbore and packer. FIG. 2 is an illustration of the present invention. FIG. 3 shows the inactive state of one embodiment of the present invention. FIG. 4 shows the active state of the embodiment of FIG. 3. FIG. 5 shows another embodiment of the present invention, including nozzles. FIG. 6 shows another embodiment of the present invention, including explosives. FIG. 7 shows another embodiment of the present invention, including creating a suction. FIG. 8 shows another embodiment of the present invention, including swelling the wellbore wall. FIG. 9 shows another use for the present invention. DETAILED DESCRIPTION FIG. 1 illustrates a prior art system, in which a tubing 2 is deployed in a wellbore 4 that extends from the surface 5 and intersects a formation 6. Typically and depending on whether the wellbore is a producing or injecting wellbore, hydrocarbons (such as oil or gas) are either produced from the formation 6, into the wellbore 4, into the tubing 2 through tubing openings 8 (such as slots or valves), and to the surface 5, or fluids (such as water or treating fluid) are injected from the surface 5, down the tubing 2, through the openings 8, and into the formation 6. In the prior art, a packer 10 is usually deployed on the tubing 2 to anchor the tubing 2 against the wellbore wall 12. Packer 10 also seals against the wellbore wall 12 in order to restrict the path of the fluid being produced or injected to below the packer 10. In some embodiments, packer 10 isolates a shale section in the earth from the formation 6 to prevent shale migration in the annulus below the packer 10. As is known in the art, shale can plug sand screens that may be used as a sand filter prior to the openings 8. When more than one formation is intersected by a wellbore, packers are also used to isolate formations from each other. Zonal isolation is useful in order to independently control the flow from each formation, and, if desired, to avoid co-mingling of formation effluents. A general schematic of the present invention 20 is illustrated in FIG. 2. In this Figure, a wellbore 22 extends from the surface 24 and intersects at least one formation 26, 28 (two formations are shown). Zones 36, 38 of earth, which can be made up of a variety of geological characteristics, are typically located between formations 26, 28. A tubing 30 is deployed within the wellbore 22, which tubing 30 includes openings 32, 34 that provide fluid communication between the interior of the tubing 30 and a corresponding formation 26, 28. As described with respect to FIG. 1, wellbore 22 can be a producing or an injecting wellbore (determined by whether fluid flows out of or into the formations). Formation 26, 28 may include hydrocarbons. Instead of utilizing a packer or another tool carried on the tubing to seal against the wellbore wall 40, the present invention 20 brings the wall 40 (or sections 37, 39 thereof) into sealing engagement with the tubing 30. The earth sections 37, 39 that create the requisite seal against tubing 30 are created either by collapsing the relevant parts of zones 36, 38 inwardly (such as by either mechanically, hydraulically, or explosively unloading the sections) or by causing the relevant parts of zones 36, 38 to swell inwardly. In other words, the present invention alters the chemical and/or mechanical conditions of the wellbore to bring the wall of the wellbore into sealing contact with the tubing 30. FIGS. 3 and 4 illustrate one embodiment that can be used to mechanically unload the relevant parts of a zone 36, 38 and wall 40. In this embodiment, a sealing unit 50 of the present invention is incorporated along the tubing 03 at each location where a seal is required along the wellbore 22. Each sealing unit 50 includes at least one scraper arm 52 and a holder 54. FIG. 3 shows the sealing unit 50 in its inactive state 56, while FIG. 4 shows the sealing unit 50 in its active state 58. It is understood that tubing 30 can comprise a plurality of tubing sections, each of which is deployed separately into the wellbore and some of which can include a sealing unit 50. In the inactive state 56, the scraper arms 52 and holder 54 are not deployed outwardly and are located proximate the sealing unit 50 or tubing 30. In one embodiment, each scraper arm 52 is pivotably connected to the sealing unit 50 at a pivot point 60. Each scraper arm 52 may be constructed from a material hard enough to scrape the earth proximate the wellbore wall 40. Satisfactory materials for scraper arm 52 include metal materials commonly used in downhole conditions. Also in one embodiment, the holder 54 is pivotably connected to the sealing unit 50 at a pivot point 62. The holder 54 may be constructed from a material strong enough to support the weight of the earth that makes up the sealing extensions (such as earth sections 37 and 39 of FIG. 2). In the active state 58, the scraper arms 52 and holder 54 are pivoted outwardly toward the wellbore wall 40 about their corresponding pivot points 60, 62. The length of each scraper arm 52 is such that the arm end 53 distal to the pivot point 60 is embedded in the earth when in the active state 58. In one embodiment, the angle 64 that each scraper arm 52 makes with the sealing unit 50 when in the active state 58 is an acute angle. An arm stop 66 deployed with each scraper arm 52 maintains the scraper arm 52 at no more than the acute angle 64 from the sealing unit 50 thereby preventing the forces applied by the earth as the sealing unit 50 is forced downward from overbending or overpivotting the scraper arms 52. A spring 68, such as a torsion spring, is deployed about the pivot point 60 biasing scraper arm 52 outwardly to become embedded within the earth. The length of holder 54 is such that the end 55 distal to the pivot point 62 is dragged along the wellbore wall 40 as the sealing unit 50 is forced downward when the sealing unit 50 is in the active state 58. In one embodiment, the holder distal end 55 is bent slightly in the upward direction so as to prevent or reduce the chance of it embedding in the earth. In one embodiment, the angle 70 between the holder 54 and the sealing unit 50 is an acute angle when the sealing unit 50 is in the active state 58. A spring 72, such as a torsion spring, is deployed about the pivot point 62 biasing holder 54 outwardly toward the wellbore wall 40. The scraper arms 52 and holder 54 are locked in the inactive state 56 by a locking mechanism 80 as the tubing 30 and sealing unit 50 are deployed in the wellbore 22. When the operator is ready to deploy the scraper arms 52 and holder 54, a signal is sent from the surface 24 to the sealing unit 50 to cause the unlocking of the locking mechanism 80 thereby enabling the scraper arms 52 and holder 54 to deploy from the inactive state 56 to the active state 58. Lock mechanism 80 may comprise a shear pin 82 attached between each scraper arm 52 and the sealing unit 50 and a shear pin 82 attached between the holder 54 and the sealing unit 50. In this case, the signal can comprise applied pressure from the surface (transmitted via the tubing 30 interior or via a control line) that shears the shear pins 80, allowing the springs 68, 72 to bias the scraper arms 52 and holder 54 outwardly from the inactive state 56 to the active state 58. In operation, a sealing unit 50 is incorporated along the tubing 30 at each location where a seal is required along the wellbore 22. The tubing 30 is deployed and when the sealing units 50 are proximate to their appropriate locations, the scraper arms 52 and holder 54 are deployed from the inactive state 52 to the active state 54. The tubing 30 is then forced downwards, which embeds scraper arms 52 into the earth, causing some of the earth 84 proximate the wellbore wall 40 to fall into the annulus and collect and accumulate on top of the holder 54 (which is dragging along the wellbore wall 40). As tubing 30 is forced downward to its appropriate location, earth 84 becomes packed between the scraper arms 52 and the holder 54 thereby providing an effective seal between the tubing 30 and the wellbore wall 40. Thus, earth sections 37 and 39 may be created by this embodiment of the sealing unit 50 to seal against the tubing 30. FIG. 5 illustrates one embodiment that can be used to hydraulically unload the relevant parts of a zone 36, 38. In this embodiment, a sealing unit 50 of the present invention is incorporated along the tubing 30 at each location where a seal is required along the wellbore 22. Each sealing unit 50 includes at least one nozzle 90 and a holder 54. The holder 54 may function as described in relation to the embodiment illustrated in FIGS. 3 and 4. Instead of the scraper arms 52, the embodiment of FIG. 5 includes at least one nozzle 90. Each nozzle 90 is in fluid communication with a pressurized fluid source 92 typically located at the surface 24. The fluid communication can be provided through the interior of tubing 30 or through control lines connecting the nozzles 90 and the fluid source 92. Once the tubing 30 and sealing unit 50 are in their appropriate downhole locations, the holder 54 is deployed (as described above) and then the fluid source 92 is activated. The fluid source 92 pumps fluid through the nozzles 90 in a stream 91 and at the wellbore wall 40 with enough force that parts of earth are dislodged from the wellbore wall 40 and accumulate on top of the holder 54. Eventually, earth 84 becomes packed on top of the holder 54 thereby providing an effective seal between the tubing 30 and the wellbore wall 40. Thus, earth sections 37 and 39 may be created by this embodiment of the sealing unit 50 to seal against the tubing 30. FIG. 6 illustrates one embodiment that can be used to explosively unload the relevant parts of a zone 36, 38. In this embodiment, a sealing unit 50 of the present invention is incorporated along the tubing 30 at each location where a seal is required along the wellbore 22. Each sealing unit 50 includes at least one explosive 100 and a holder 54. The holder 54 may function as described in relation to the embodiment illustrated in FIGS. 3 and 4. Instead of the scraper arms 52, the embodiment of FIG. 6 includes at least one explosive 100. Each explosive 100 can be activated as known in the prior art (in relation to perforating guns), such as by signals down control lines, pressure pulses, drop bars, applied pressure, or wireless telemetry (including acoustic, electromagnetic, pressure pulse, seismic, and mechanical manipulation telemetry). It is noted that FIG. 6 illustrates the sealing unit 50 including the explosives 100 prior to activation. When activated, each explosive 100 explodes towards the wall 40 and earth thereby causing a portion of the earth to dislodge from the wellbore wall 40 and accumulate on top of the holder 54. Eventually, earth becomes packed on top of the holder 54 thereby providing an effective seal between the tubing 30 and the wellbore wall 40. Thus, earth sections 37 and 39 may be created by this embodiment of the sealing unit 50 to seal against the tubing 30. FIG. 7 illustrates one embodiment that can be used to hydraulically unload the relevant parts of a zone 36, 38. In this embodiment, a sealing unit 50 of the present invention is incorporated along the tubing 30 at each location where a seal is required along the wellbore 22. Each sealing unit 50 includes two sets of rubber cups 120A, 120B and at least one port 122 located on the tubing 30 between the cups, 120A and 120B. Each rubber cup set 120A, 120B may include one or more rubber cups. The interior of tubing 30 is in fluid communication with a suction source 124. To operate this embodiment of the sealing unit 50, the suction source 124 is activated, which results in the creation of a low pressure and suction area in the interior of the tubing 30 as well as in the annulus 124 between the cup sets 120A, 120B (through the ports 122). The cup sets 120A, 120B effectively allow the creation of this suction area therebetween since each set is sized to abut the wellbore wall 40. Once the suction is great enough, it will cause portions of the earth to dislodge from the wellbore wall 40 and flow towards the ports 122. A filter 126 positioned outside of or in the interior of the tubing 30 allows the suction to communicate through the ports 122 but does not allow the dislodged earth sections to flow into tubing 30. After some time, the suction source 124 is deactivated thereby allowing the dislodged earth sections to fall on top of the bottom cup set 120B. Eventually, earth becomes packed on top of the bottom cup set 120B thereby providing an effective seal between the tubing 30 and the wellbore wall 40. Thus, earth sections 37 and 39 may be created by this embodiment of the sealing unit 50 to seal against the tubing 30. FIG. 8 illustrates one embodiment that can be used to swell the relevant parts of a zone 36, 38. In this embodiment, a sealing unit 50 of the present invention is incorporated along the tubing 30 at each location where a seal is required along the wellbore 22. Each sealing unit 50 includes at least one outlet 110. Each outlet 110 is in fluid communication with a chemical source 112. Although the source 112 is shown as being located at the surface 24, the source 112 may also be located downhole. The fluid communication can be provided through the interior of tubing 30 or through control lines connecting the outlets 90 and the chemical source 92. Once the tubing 30 and sealing unit 50 are in their appropriate downhole locations, the chemical source 112 is activated to distribute fluid through the outlets 110 in a stream 111 at the wellbore wall 40. The chemical distributed by the chemical source 112 is one that causes the relevant parts of zones 36, 38 to swell. The selection of the correct chemical depends on the geological characteristics of the zones 36, 38. The chemical should be selected so that the relevant parts of zones 36, 38 swell to abut and seal against the tubing 30 thereby providing an effective annular seal. Thus, earth sections 37 and 39 may be created by this embodiment of the sealing unit 50 to seal against the tubing 30. The chemical can be in the form of a liquid, gel, or paste. Gel or liquid would prevent free flow. Alternatively, temporary sealing members like rubber packers, cups, etc. can be run with sealing unit 50 to seal off both ends of sealing unit 50 to form a closed chamber. In this embodiment, the chemical is released and retained in the closed chamber. Chemicals may also be used in conjunction with the embodiments that mechanically, explosively, or hydraulically unload the zones 36, 38 to create the earth sections 37, 39 that seal against the tubing 30. For instance, a chemical to soften the relevant wall section may be distributed on such section before the unloading of the zones 36, 38. Also, a chemical to bond the earth 84 that makes up the earth sections 37, 39 can be distributed after the unloading of the zones 36, 38. Other chemicals may also be used. For instance, a thyxotropic gel can be placed via a ported collar into the annulus, which gel chemistry can alter the borehole conditions triggering a wellbore wall collapse. If chemicals are used, a fluid communication system similar to that described in relation to FIG. 8 would also be implemented. Combinations of the different sealing unit embodiments are also possible. For instance, the embodiments used to hydraulically or explosively unload the zones 36, 38 may be combined with the embodiments used to mechanically unload the zones 36, 38. Other combinations are possible. It is noted that the pressure that will be maintained by the earth sections 37, 39 will depend on the porosity and compactness of the earth 84 that makes up the earth sections 37, 39. Such porosity and compactness may be affected to provide a more efficient and thorough seal, such as by adding a chemical (like the bonding chemical) to the earth sections 37, 39, as described above. The present invention is a system and method by which to create a seal between an open wellbore and a tubing by bringing the wellbore wall into sealing contact with the tubing. For its principal use, the present invention does not utilize prior art packers and therefore does not contain any of the difficulties found in deploying, activating, and maintaining such packers. Another use of the present invention is shown in FIG. 9. In this embodiment, the sealing unit 50 is used to extend the sealing area created between two prior art packers. The operation of this embodiment is the same as the embodiment described in relation to FIG. 7, but instead prior art packers 130A, 130B are used to define the annulus 124 that is in communication with the at least one port 122. The prior art packers 130A, 130B can comprise rubber packers, cup packers, hydraulically set packers, electrically set packers, mechanically set packers, swellable packers, or any other packer known in the prior art. The present invention is useful as illustrated situations when the sealing area A provided by a single prior art packer is not large enough. For instance, in some cases fluid may flow through the earth from below a prior art packer (such as 130B) to above the prior art packer, if the sealing area (such as A) provided by such packer is not large enough. On the other hand, if the sealing area is increased to A″ by the use of the present invention and another prior art packer (such as 130A), then the likelihood of flow across the sealing area A″ is greatly reduced. The present invention has been illustrated and described as being a replacement or enhancement to prior art packers in that the sealing area provided by the present invention is small relative to the length of the wellbore. However, the present invention can also be used to provide a sealing area that is substantial in relation to the wellbore length or that even comprises the entire or most of the wellbore length. For instance, the sealing area can be enlarged by enlarging the distance between the holder 54 and scraper arms 52 of FIGS. 3 and 4, the nozzles 90 and the holder 54 of FIG. 5, the explosives 100 and the holder 54 of FIG. 6, the cup sets 120A and 120B of FIG. 7, and the prior art packers 130A and 130B of FIG. 9. The sealing area can also be enlarged by incorporating additional scraper arms 52 (FIGS. 3 and 4), nozzles 90 (FIG. 5), explosives 100 (FIG. 6), outlets 110 (as in FIG. 8), and ports 122 (FIGS. 7 and 9). Other embodiments are within the scope of the following claims. For example, although the seals created by the present invention were shown to be created in a vertical wellbore, the present invention and its seals may also be created in horizontal, inclined, or lateral tracks or wellbores. In other examples, the holder 54 of FIGS. 3, 4, 5, and 6 may be substituted by a cup set 120 of FIG. 7. Also, instead of using ports 122, the embodiments of FIGS. 7 and 9 may use ported collars (as known in the field). In addition, a downhole seismic vibrator can be used to cause the collapse of the wellbore wall instead of, for instance, the explosives 100 of FIG. 6. Other variations are possible. While the present invention has been described with respect to a limited number of embodiments, those skilled in the art, having the benefit of this disclosure, will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of this present invention.

<SOH> BACKGROUND OF INVENTION <EOH>The invention generally relates to a system and method to seal by bringing the wall of a subterranean wellbore into sealing contact with an interior tubing. More specifically, the invention relates to a sealing system that causes the wall of a wellbore to collapse or swell and thereby provide a seal against a tubing located within the wellbore. Sealing systems, such as packers or anchors, are commonly used in the oilfield. Packers, for instance, are used to seal the annular space between a tubing string and a surface exterior to the tubing string, such as a casing or an open wellbore. Commonly, packers are actuated by hydraulic pressure transmitted either through the tubing bore, annulus, or a control line. Other packers are actuated via an electric line deployed from the surface of the wellbore. The majority of packers are constructed so that when actuated they provide a seal in a substantially circular geometry. However, in an open wellbore, packers are required to seal in a geometry that is typically not substantially circular. Thus, there is a continuing need to address one or more of the problems stated above.

<SOH> SUMMARY OF INVENTION <EOH>The invention is a system and method used to seal between an open wellbore and a tubing by bringing the wellbore wall inwardly so as to enable sections of earth from the wellbore wall to create the required seal against the tubing. The earth sections that make up the seal can be created by collapsing the relevant parts of the wellbore wall inwardly or by causing the relevant parts of the wellbore wall to swell inwardly. Advantages and other features of the invention will become apparent from the following drawing, description and claims.

20040401

20060620

20051006

91423.0

DANG, HOANG C

SYSTEM AND METHOD TO SEAL BY BRINGING THE WALL OF A WELLBORE INTO SEALING CONTACT WITH A TUBING

UNDISCOUNTED

ACCEPTED

ACCEPTED

WIRE STRAPPER FOR WASTE MATERIAL BALER

A wire strapping or tying device (46) is provided having a rotatable pinion-type knotter assembly (56) for twist-knotting of a pair of adjacent wire sections (50a, 50b), together with a shiftable knotter cover (266) movable between a home position for maintaining the sections (50a, 50b) within the assembly (56) and a remote knotter access position allowing ready access to the knotter assembly (56). The cover (266) is supported by arms (268, 270) which are pivotal about an axis spaced from and generally parallel with the cover (266). The cover (266) may be manually shifted to the remote knotter access position through an arc of at least 45°. Also, the knotter assembly (56) includes a primary body (128) supporting a rotatable, slotted knotter pinion (178). The body (128) is pivotally secured to frame plates (68, 70), allowing the body (128) to be pivoted to a convenient position for servicing of pinion (178). Preferably, a mechanical operator assembly (198) is employed to sequentially operate all of the device components in a precise, timed sequence. A single drive assembly (196) preferably in the form of a piston and cylinder assembly (200) is used to actuate the assembly (198).

1. In a knotting device including a rotatable knotter operable to twist-knot a pair of adjacent wire sections, and a cover located adjacent said knotter for maintaining the wire sections within the knotter during feeding and knotting operations, the improvement which comprises a mount for said cover permitting the cover to be pivoted away from said knotter to a knotter access position remote from said wire-maintaining position and through a pivot arc of at least about 90°. 2. The device of claim 1, said arc being greater than about 120°. 3. The device of claim 1, said knotter comprising a slotted, rotatable pinion adapted to receive within the slot thereof said adjacent wire sections. 4. The device of claim 1, including a spring operably coupled with said cover for biasing the cover up to said wire-maintaining position thereof. 5. The device of claim 4, said spring also operable to bias the cover to said knotter access position upon pivoting of the cover to the knotter access position. 6. The device of claim 5, said spring secured to said cover and shiftable over center with the cover. 7. The device of claim 1, said mount comprising a leg secured to said cover and pivotal about an axis remote from said cover and generally parallel thereto. 8. The device of claim 1, said knotter rotatably mounted on an elongated support body, said body being selectively rotatable when said cover is in said knotter access position to a non-operative position permitting ready replacement or repair of the knotter. 9. The device of claim 8, including an upright frame member proximal to said knotter, said support body being releasably secured to said frame member and pivotal relative thereto to move the support body and knotter to said non-operative position. 10. The device of claim 1, said cover being manually shiftable from said wire-maintaining position to said knotter access position. 11. In a knotting device including a knotting assembly having a gripper for selectively gripping one of two adjacent wire sections, a rotatable knotter operable to twist-knot the two adjacent wire sections, a cutting element for cutting of the other of said adjacent wire sections after twist-knotting of the sections and a shiftable cover located adjacent said knotter for maintaining the wire sections within the knotter during feeding said twist-knotting and thereafter movable to a wire-clearing position permitting passage of the twist-knotted wire sections from the knotter, the improvement which comprises an operator assembly for timed operation of said gripper, knotter, cutting element and cover, and a single drive assembly coupled with said operator assembly for effecting said timed operation. 12. The device of claim 11, said drive assembly comprising a piston and cylinder assembly including a reciprocal piston rod operably connected with said operator assembly. 13. The device of claim 11, said operator assembly including a pivotal shaft assembly carrying respective operator bodies for said gripper, knotter, cutting element and cover. 14. The device of claim 13, said cover attached to a mount for pivotal movement of the cover between said wire-maintaining position and said wire-clearing position, including a spring operably coupled with said cover mount for biasing the cover to said wire-maintaining position thereof, said cover operator body configured to engage said cover mount to move the cover from said wire-maintaining position to said wire-clearing position. 15. The device of claim 14, said cover mount permitting selective pivoting of the cover from said wire-maintaining position to a remote knotter access position and through an arc of at least about 90°. 16. The device of claim 15, said spring acting to maintain said cover in said knotter access position. 17. The device of claim 15, said knotter rotatably mounted on an elongated support body, said body being selectively rotatable when said cover is in said knotter access position to a non-operative position permitting ready replacement or repair of the knotter. 18. The device of claim 17, including an upright frame member proximal to said knotter, said support body being releasably secured to said frame member and pivotal relative thereto to move the support body and knotter to said non-operative position. 19. In a knotting device including a rotatable knotter operable in one position thereof to twist-knot a pair of adjacent wire sections, and a cover located adjacent said knotter for maintaining the wire sections within the knotter during feeding and knotting, the improvement which comprises a mount for said knotter permitting the knotter to be pivoted from said one position to an access position allowing servicing of the knotter. 20. The device of claim 19, said knotter comprising a slotted, rotatable pinion adapted to receive within the slot thereof said adjacent wire sections. 21. The device of claim 19, said knotter mount comprising an elongated support body, said body being selectively rotatable to said access position. 22. The device of claim 21, including an upright frame member proximal to said knotter, said support body being releasably secured to said frame member and pivotal relative thereto to move the support body and knotter to said access position. 23. The device of claim 22, including a threadable connector securing said support body to said frame member.

BACKGROUND OF INVENTION 1. Field of the Invention The present invention is broadly concerned with wire strapping apparatus of the type used to apply knotted and tensioned wire ties to preformed bales such as compressed refuse bales. More particularly, the invention is concerned with such apparatus having features permitting quick and easy access to critical wire knotting components, so that the user may readily clear, repair and/or replace such components as necessary. 2. Description of the Prior Art Various wire tying and strapping machines have been proposed in the past for applying knotted and tensioned wire ties to bales, packages or other articles. One class of these prior machines makes us of a continuous, two-piece wire track with an associated strapping device. In such units, a package or bale to be tied is positioned within the confines of the wire track, and a continuous strand of wire is advanced completely around the track and overlapped with itself. The wire is then tensioned and the overlapped sections are knotted together by twisting. This further tensions the wire to the point that the track sections are separated allowing the knotted and tensioned tie to snap into place about the bale or article. In some cases more complex devices are provided for ejecting the knotted wire from the track. Commonly, a twister pinion is employed for twist-knotting of adjacent wire sections. Such a knotter pinion includes a slot to accommodate the wire sections and upon rotation of the pinion a defined number of turns or twists are created. In order to maintain the wires in the twister pinion and associated structure, a shiftable knotter cover located adjacent the twister pinion is used. A significant problem with prior machines is the difficulty of readily clearing or servicing the twister pinion and related structure. Hence, in one prior machine design, it is necessary to physically detach the cover and disassemble the pinion apparatus for servicing purposes. In other instances, the cover is movable to only a very limited extent, making it very difficult to access the pinion. Prior art patents relating to strapping devices include U.S. Pat. Nos. 4,777,554, 3,295,436, 2,922,359, and 4,817,519. SUMMARY OF INVENTION The present invention overcomes the problems outlined above and provides an improved knotting device of the type including a rotatable knotter operable to twist-knot a pair of adjacent wire sections and having a cover located proximal to the knotter for maintaining the wire sections within the knotter during knotter operations. In particular, the improved device has a mount for the knotter cover permitting the cover to be pivoted away from the knotter to a knotter access position remote from the home or wire-maintaining position and through an arc of at least about 45°, more preferably greater than about 60°, and most advantageously around 90°. Preferably, the rotatable knotter is in the form of a slotted, rotatable pinion adapted to receive adjacent wire sections within the slot thereof, and the associated knotter cover is mounted on a leg pivotal about an access remote from the cover and generally parallel thereto. An over center spring is secured to the cover mount for biasing the cover to its home position, and also biasing the cover to its knotter access position when the cover is shifted away from the knotter. In further preferred forms of the invention, the rotatable knotter is mounted to an elongated, axially pivotal support body. The body is mounted to a stationary frame member by way of a threaded couplers or any convenient means. Thus, when the cover is in its remote position, it is a simple matter to loosen the threaded couplers and rotate the support body to a position facilitating access to rotatable knotter. In another aspect of the invention, a knotting device is provided having a knotting assembly comprising a gripper for selectively gripping one of two adjacent wire sections, a rotatable knotter operable to twist-knot the adjacent sections, a cutting element for cutting the other of the adjacent wire sections after twist-knotting of the sections, and a shiftable cover adjacent the knotter for obtaining the wire sections within the knotter during twist-knotting and thereafter movable to a wire-clearing position permitting passage of the twist-knotted wire sections from the knotter. In this case an operator assembly is provided for timed operation of the gripper, knotter, cutting element, and cover and a single drive assembly (e.g., a piston and cylinder assembly) is coupled with the operator assembly for effecting the timed operation. Use of only a single drive assembly makes it possible to mechanically time the knotting device on a very precise basis. This in turn facilitates and speeds up the overall wire tying sequence. Preferably, the operator assembly includes a pivotal shaft carrying respective mechanical operator bodies for the gripper, knotter, cutting element and cover. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an isometric view of a dual-ram refuse baler equipped with the wire strapper of the present invention; FIG. 2 is an isometric view of the strapping device forming a part of the overall wire strapper, depicting the device in the ready position thereof before initiation of a strapping operation; FIG. 3 is an isometric view similar to that of FIG. 2, but viewing the device from the opposite side illustrated in FIG. 2; FIG. 4 is a front elevational view of portions of the strapping device, including the main frame assembly, knotter assembly, torque tube assembly, gear hub and knotter cover assembly, the gripper assembly and the exit assembly; FIG. 5 is a fragmentary isometric view illustrating details of construction of portions of the main frame assembly, torque tube assembly and the gear hub and knotter cover assembly; FIG. 6 is a fragmentary isometric view illustrating portions of the torque tube assembly, and the gear hub and cover assembly; FIG. 7 is a fragmentary isometric view of portions of the torque tube assembly; FIG. 8. is an isometric view similar to that of FIG. 2 with the pinch roll and entry assemblies deleted, and showing the knotter cover in its elevated access position and with the knotter assembly open for access; FIG. 9 is an exploded isometric view illustrating the components of the gripper assembly; FIG. 10 is an exploded isometric view of the components of the knotter assembly; FIG. 11 is a vertical sectional view taken along line 11-11 of FIG. 4 and illustrating the wire cutter forming a part of the knotter assembly prior to operation of the wire cutter; FIG. 12 is a vertical sectional view similar to that of FIG. 11, but depicting the cutter after the wire has been cut; FIG. 13 is a vertical sectional view taken along line 13-13 of FIG. 11 and illustrating the knotted strapping wire prior to cutting thereof; FIG. 14 is a fragmentary vertical sectional view taken along line 14-14 of FIG. 6 and illustrating release of the gripping assembly by the action of the torque tube assembly; FIG. 15 is a vertical sectional view taken along line 15-15 of FIG. 4 and showing the action of wire removal fingers prior to engagement of a knotted wire within the knotter pinion; FIG. 16 is a view similar to that of FIG. 15 but showing the knotted wire fully removed from the knotting opinion; FIG. 17 is a fragmentary, sectional isometric view illustrating the interengagement between the knotting pinion and the sector gear forming a part of the gear hub and knotter cover assembly, prior to commencement of the wire knotting operation; FIG. 18 is a fragmentary, sectional view illustrating a wire within the knotting pinion with the knotting cover in its operative position; FIG. 19. is a view similar to that of FIG. 18, but illustrating the knotting pinion during a wire knotting operation; FIG. 20 is a view similar to that FIG. 19, but showing the cover displaced from the knotting pinion in order to permit withdrawal of the knotted wire from the pinion; FIG. 21 is a sectional view taken along line 21-21 of FIG. 4, and illustrating the knotter and gripper assemblies, prior to initiation of a baling operation; FIG. 22 is a sectional view similar to that of FIG. 21, but showing a wire within the knotter and gripper assemblies, with the latter holding the wire in place; FIG. 22a is a cross-sectional view taken along line 22a-22a of FIG. 22, particularly showing the gripped end section of the wire below the other section of wire; and FIG. 23 is a view similar to that FIG. 22, but showing the gripper in its release position. DETAILED DESCRIPTION Turning now to the drawing, FIG. 1 illustrates a double ram refuse baler 30 designed to receive and compress refuse into large bales, and to eject such bales with one or more tensioned and knotted wires around the bale. Broadly, the baler 30 includes a compression ram chamber 32, an ejection ram chamber 34, an inlet hopper 36, a bale outlet 38, and a wire strapper 40 disposed about the outlet 38. The baler 30 is powered by means of a multiple stage hydraulic power unit 42. In operation, refuse is loaded into hopper 36 and is compressed using a ram (not shown) within chamber 32 to create an appropriately sized bale which is moved into the transverse chamber 34. Another ram (also not shown) within chamber 34 serves to eject the compressed bale through outlet opening 38. During the course of or after such ejection, the strapper 40 is operated to place one or more tensioned and knotted wire ties about the formed bale which can then be disposed of in conventional fashion. Balers of the type shown in FIG. 1 are available from a number of sources, such as Marathon Equipment Co. Broadly speaking, the wire strapper 40 includes a spring-loaded, separable wire guide track 44 substantially circumscribing the opening 38, as well as a strapping device 46 located above the opening 38. A separate wire stand 48 is provided which has a supply of wire 50 which is fed to the inlet of device 46 during strapping operations. The device 46 includes a number of assemblies operating in cooperation for effective bale tying. Again broadly speaking, the device 46 has (see FIGS. 2 and 3) a main frame assembly 51, pinch roll assembly 52, a wire entry assembly 54, a knotter assembly 56, a torque tube assembly 58, a hub gear and knotter cover assembly 60, a wire gripper assembly 62 and an exit assembly 64. As shown, opposed ends of the guide track 44 mate with the entry assembly 54 and exit assembly 64 respectively, so as to create a continuous wire path. The frame assembly 51 is a rigid frame and has a bottom plate 66 and a pair of upstanding, apertured side plates 68, 70. It additionally has a laterally projecting plate 72 affixed to plate 70 and serving as a mount for pinch roll assembly 52. Finally, an upper cross-plate 74 is attached to and spans the side plates 68, 70 and is equipped with a large opening 76. A pair of upstanding bearing blocks 78, 80 are attached to the upper face of cross-plate 74 of opposite sides of opening 76. The pinch roll assembly 52 includes a main, rearmost frame plate 82 supporting a pair of spaced apart subframes 84, 86 with a wire feeder 88 located between the subframes 84, 86 and having a wire entrance opening 90. As best seen in FIG. 2, a drive gear 92 is mounted on subframe 84 and is connected to a rearwardly extending drive motor 94. The gear 92 is in meshed, driving engagement with upper and lower gears 96, 98 housed within subframe 84; each of the gears 96, 98 carries a peripherally recessed wire gripper 100, 102. Mating gears 104, 106 are housed within subframe 86 and likewise carry peripherally recessed wire grippers 108, 110. A pair of upper and lower wire guides 112, 114 are also situated between the subframes 84, 86. The pinch roll assembly 52 is operable, as explained in more detail below, to draw the wire 50 from stand 48 downwardly through the pinch roll assembly into entry assembly 54 and the remainder of device 46. Thus, when drive gear 92 is rotated in a counterclockwise fashion as viewed in FIG. 2, gears 96, 98 and 104, 106 are rotated along with the associated grippers 100, 102 and 108, 110. This serves to pull the wire downwardly through the pinch roll assembly towards entry assembly 54. Likewise, rotation of the drive gear in a clockwise direction serves to retract the wire 50. It will be appreciated that the wire 50 travels through the feeder 88 and is cooperatively engaged by the grippers 100, 102 and 108, 110, being further guided by the guides 112, 114, for the purposes described. Although the assembly 52 as described is preferred, it will be appreciated that a variety of other functional pinch roll assemblies could also be employed. See, e.g., U.S. Pat. No. 4,817,519. The entry assembly 54 includes an obliquely oriented plate 116 affixed to plate 72, as well as a pair of three laterally extending plates 118, 119, 120 which are supported by the plate 72. The plates 116, 72 cooperatively define a wire path leading from the wire outlet of pinch roll assembly 52 downwardly towards the plates 118-120. Plate 119 is configured to present an elongated wire path in alignment with the path defined by the plates 116, 72 thus forming a continuous wire path through assemblies 52, 54 and into the knotter assembly 56. As best seen in FIG. 3, a wire path 122 is defined between the plates 119 and 120, which communicates with the path defined by the guide track 44. The assembly 54 also includes a pair of spring clips 124, 126 serving to yieldably retain plate 120 adjacent plate 119. An L-shaped connector 127 serves to interconnect the assembly 54 with the adjacent end of continuous track 44. The knotter assembly 56 includes (see FIG. 10) a primary block 128, cutter element 130 and knotter pinion assembly 132. The block 128 has a central section including a U-shaped segment 134 having a pair of upstanding wall sections 136, 138 with an opening 140 therebetween. The lower portion of segment 134 presents an arcuate surface 142. Elongated slots 144, 146 are provided on either side of the wall sections 136, 138. The ends of block 128 are equipped with upstanding apertured connector bodies 148, 150 which are designed for swingable attachment to the inboard faces of the frame walls 68, 70 via threaded connectors 151 (see FIGS. 2 and 3). The block 128 is normally retained in the operating position (shown in FIGS. 2 and 3) by removable threaded fasteners 153. However, the fasteners 153 can be removed so that the block 128 can be swung upwardly on connectors 151 to the maintenance position (shown in FIG. 8). Knife element 130 is secured to the right-hand end of block 128 as viewed in FIGS. 10 and 13. The element 130 includes an obliquely and upwardly oriented section 152 having a laterally projecting follower 154 adjacent the upper end thereof. The lower end of the cutter includes a mounting bore 156, lowermost wire shearing surface 158 and spring-receiving recess 160. The element 130 is secured to block 128 by means of U-shaped end connector 162 which carries a pivot pin 164. Thus, the pin 164 extends through the bore 156 and seats within an aligned bore 166 provided in the butt end of body 128, allowing pivoting of the element 130. Coupler 168 extend through the ends of connector 162 and into corresponding tapped bores 170 in the block 128. A pair of bias springs 171 are seated within recess 160 with their opposite ends engaging the inner face of connector 162. The knotter pinion assembly 132 includes a pair of arcuate bushings 172, 174 which are secured to the arcuate surface 142 of segment 134 via oblique couplers 175. The bushings 172, 174 support the opposed ends of pinion member 176 having a central pinion gear 178 and laterally extending support sections 180, 182 which are engaged by the corresponding bushings. It will be noted that the bushings, support sections and the pinion gear have mating, wire-receiving slots 172a, 174a, 178a, 180a, 182a which are important for purposes to be described. A pair of wire guide blocks 184, 186 are affixed to block 128 on opposite sides of pinion assembly 132 and have an open lower end for passage of wire sections therethrough. As best seen in FIG. 10, the right-hand ends of the blocks have a tapered wire guiding surface 184a, 186a. A right-hand wire guide block 187 having a wire passageway 187a is secured to the underside of block 128 between block 186 and the lower extent of element 130. Also, a left-hand end wire guide block 190 carrying a secondary gripper block 191 and having a lower wire passageway 192 is affixed to the left-hand end of block 128 beneath connector body 148. Referring to FIG. 13, it will be seen that the lower end of cutter element 130 adjacent shearing surface 158, wire passageway 187a, block 186, pinion assembly 132, block 184 and block 190 cooperatively define an elongated, open-bottom wire passageway generally referred to by the numeral 194 which extends throughout the entire length of the knotter assembly 56. This passageway 194 is sized so as to simultaneously accommodate separate, upper and lower segments of wire, namely a section of wire 50a extending entirely around the guide track 44 and along passageway 194 and a lower wire section 50b extending through passageway 194 (see FIG. 22a). The torque tube assembly 58 is best illustrated in FIGS. 5-7, and generally includes a drive assembly 196 as well as an operator assembly 198. The drive 196 includes a piston and cylinder device 200 comprising an elongated hydraulic cylinder 202 having a central mounting block 204 equipped with laterally extending trunnions 206. The cylinder 202 extends through opening 76 of crossplate 74 with the trunnions 206 supported by the bearing blocks 78, 80. In this fashion, the cylinder 202 may rock or pivot relative to the blocks 78, 80 and crossplate 74. The assembly 200 also includes an reciprocal piston rod 208 equipped with a lower most clevis 210. The cylinder 200 is operatively equipped with a source of pressurized hydraulic fluid (not shown). The operator assembly 200 includes a cross shaft 212 supported on endmost bearings 214. A mounting shaft 216 supports the bearings 214 and extends through cross shaft 212; the shaft 216 is in turn secured to frame plates 68, 70. A total of four operating arms are fixedly secured to cross shaft 212 in spaced relationship along the length thereof, namely a crank and gripper operator 218, a pair of mating hub gear and ejector operators 220, 222 and a cutter operator 224. The crank and gripper operator 218 includes an elongated projecting body 226 equipped with a clevis mount 228 adjacent the outboard end thereof along with a leg 230 which supports a gripper operator element 232. The operators 220, 222 similarly include outwardly extending bodies 234, 236. The outboard end of the bodies 234, 236 have wire ejector fingers 238 and 240 secured thereto, along with rocker blocks 242, 244. Additionally, a roller 246 is disposed between the bodies 234, 236 and is supported for rotation via terminal bearing supports 248 and support pin 250. The cutter operator 224 has an extended body 252 carrying an operator block 254 adjacent the outer end thereof. As best seen in FIGS. 5 and 6, clevis 210 is pivotally coupled with mount 228 carried by operator body 226. Thus, upon extension or retraction of piston rod 208, the entire assembly 198 is correspondingly pivoted about a rotational axis defined by mounting shaft 216. The various operating components carried by the operators 218-224 are designed to operate, on a sequential basis, the operations of gripping, knotting, cutting and ejecting a final knotted bale wire for application to a compressed bale. This operation will be described in detail below. The hub gear and cover assembly 60 is best seen in FIGS. 5 and 8. This assembly includes a central sector gear 256 having a toothed face 258 in mesh with pinion gear 178, and an elongated drive slot 260. The gear 256 is secured to a transverse support shaft assembly 262 by means of coupler 264 (see FIG. 6). The ends of the shaft assembly 262 are rotatably secured at the outer ends thereof to the frame walls 68, 70 thereby allowing the shaft assembly 262 to pivot with sector gear 256. The overall hub gear and cover assembly 60 further includes a knotter cover 266 which is normally disposed beneath the knotter assembly 56. The cover 266 is in the form of an apertured plate as best seen in FIG. 8. The cover 266 is supported by a pair of upright arms 268, 270 disposed on opposite sides of gear 256. Each arm 268, 270 is mounted via appropriate bearings onto the shaft assembly 262, with the latter being rotatable relative to the arms. Each of the arms includes an inwardly extending rotatable abutment 272, 274. As best seen in FIGS. 17-20, the cover supports a rockable, spring-biased, bifurcated retainer 276 which extends inwardly and presents up-standing nibs 278. A pair of springs 280, mounted on pins 282, bias retainer 276 to its upraised position best illustrated in FIG. 20. Finally, as illustrated in FIG. 2, the arm 268 has a laterally extending spring connector 284. A coil spring 286 is extends between connector 284 and stud 288 affixed to frame wall 68. The spring 286 biases the cover 266 inwardly towards gear 256. The gripper 62 is illustrated in FIGS. 9 and 21-23. Generally, the gripper has a dogleg-shaped, wire-engaging gripper component 290 with a wire-engaging end 292 and an actuator end 294. The component 290 has a central bearing section 296 and a spring recess 298. The gripper 62 also includes a spring loaded, pivotal block 300 presenting opposed pairs of endmost connection ears 302 and 304 and a threadably attached central operator segment 305 including an inclined operating surface 306 which is important for purposes to be described. A spring assembly 308 is housed within block 300 and comprises a central coil spring 310 positioned between a retainer cap 312 having a bore 313 and a lower annular retainer 314. A headed pin 316 extends upwardly through the base 318 of block 300 and retainer 314 into the confines of spring 310. It will be noted that the ears 302 are provided with elongated slots 319, and that the ears 304 have circular openings 319a. The block 300 is supported on a connector 320 including an upright plate 322 having an upper apertured tab 324 as well as an opposed apertured tab 326, the latter having a stop block 328 secured thereto. Additionally, the plate 322 has a pair of blind spring recesses 330 adapted to receive coil springs 332. The plate 322 is directly secured to frame sideplate 68 and also supports a proximity sensor 334. A first connection pin 336 extends through the opening of tab 324, slots 319 and cap bore 313, and finally through the bore of opposed tab 326, to thereby pivotally mount one end of the block 300. Another connection pin 338 extends through the openings 319a of ears 304 and bearing section 296 of component 290 to complete the connection. A coil biasing spring 344 extends between the block 300 and is received within spring recess 298 of component 290. Additionally, the coil springs 332 are seated within the recesses 330 and engage block 300 as best seen in FIGS. 21-23. Finally, a cylinder 340 is affixed to plate 322 and has a selectively extendable rod 342 configured to engage the actuator of component 290. Exit assembly 64 includes a pair of abutting plates 346 and 348, with the plate 346 having an upstanding projection secured to the outer face of frame plate 68. The plates 346, 348 cooperatively define a wire passageway 350 which is in alignment with passageway 194 of knotter assembly 56. A spring retainer clip 351 is in bridging relationship to the plates 346, 348, in order to yieldably hold the plates together while permitting separation thereof so as to permit release of a tensioned and knotted wire bale. An L-shaped connector 352 serves to connect the exit assembly 64 with continuous track 44. Operation The operation of baler 30 will now be described in the context of applying a tensioned and knotted wire tie about a compressed refuse bale. In this discussion, it will be assumed that the strapping device is in a ready condition, i.e., that a wire has previously been applied to the same or an earlier bale, and that the leading end of the wire 50 is positioned just upstream of the wire shearing surface 158 of cutter element 130. Moreover, the gripper 62 is in the FIG. 21 released position thereof, and the torque tube assembly is in the FIG. 2-3 position thereof. When a bale is properly positioned relative to the outlet opening 38 of ejection ram chamber 34 in location to receive a knotted and tensioned wire tie, a sensor (not shown) associated with the chamber 34 sends an initiation signal to device 46. Next, the pinch roll assembly 52 is actuated via drive motor 94 and the coupled gear train in order to rotate the wire grippers 100, 102 and 108, 110 so as to advance the wire 50, and thus draw wire from the wire stand 48. Specifically, the assembly 52 advances the wire 50 along the passageway 194 through the remainder of the knotter assembly 56, exit assembly 64, and then completely around the guide track 44 until the leading end of the wire encounters wire path 122 defined by entry assembly 54. At this point the leading end of the wire passes beneath the wire section already situated within the knotter assembly 56 and the region of gripper 62. This condition is illustrated in FIG. 22a, where it will be seen that the section of wire 50a extends completely around the track 54, and the shorter section 50b lies beneath the portion of wire 50a within the knotter assembly 56. The advancement of the wire 50 continues until the leading edge thereof passes and engages the wire engaging edge 292 of gripper component 290. This causes the component 290 to slightly pivot in a clockwise direction as viewed in FIG. 21 until the component assumes the initial gripping position depicted in FIG. 22. In this orientation, the gripping end 292 engages the wire section 50a and the actuator 294 is moved to a position beneath sensor 334. The sensor 334 is capable of detecting the presence of the metallic actuator. This causes a signal to be sent to the assembly 52 to stop the advancement of wire, and to reverse the operation thereof. This begins tensioning the wire section 50a extending around track 44 to thereby draw the sections 50a and 50b taut. During the course of this reverse movement, the component 292 is moved rightwardly (FIG. 22) because of the engagement with the wire until block 328 is encountered. Further reverse wire movement draws the end 292 of component 290 into tight gripping engagement with the wire, pressing the latter against block 191. To insure the wire is gripped, cylinder 340 is actuated. The rod 342 thus engages actuator 294 in order to pivot the component 290 counterclockwise about axis pin 338, extending spring 334. The final wire-gripping position is illustrated in FIG. 22. This reverse movement of the assembly 52 continues until an appropriate tension is created in the wire, which is sensed by a sensor (not shown) associated with assembly 52. At this point the operation of the assembly 52 entirely terminates, and a signal is sent to drive assembly 196. The drive assembly 196 is then actuated in order to sequentially twist-knot the wire sections 50a, 50b, to cut the wire section 50a, to shift the cover 266 from its wire-maintaining home position, and to eject (if necessary) the knotted and tensioned wire tie from the knotter assembly 56 and through the separable sections of track 44, in order to cause the completed wire tie to envelop the refuse bale. These actions are all accomplished through the medium of the single operator assembly 198. In more detail, the piston and cylinder device 200 is actuated in order to extend rod 208. This rotates cross shaft 212 about mounting shaft 216, i.e., the clevis 210 operates to rotate crank and gripper operator 218 which thus rotates the entire assembly 198. At this point the sector gear 256 is pivoted by virtue of the roller 246 attached to the operators 220, 222 and riding within drive slot 260. Inasmuch as the toothed face 258 of gear 256 is in meshed, driving engagement with pinion gear 178, the latter is rotated. During such rotation the wire sections 50a, 50b within the pinion slot 178a and adjacent slots 180a and 182a are twisted together a desired number of turns (in the present embodiment four) along the length of passageway 194, as schematically illustrated in FIGS. 17-19. During such twisting operation, the retainer 276 and specifically nib 278 thereof serve to maintain the wire sections within the stationary sections 180, 182, while the cover 266 ensures that the remainder of the wires remain within passageway 194. Next, the cutter operator 224 comes into play by engagement of block 254 with the follower 154 secured to the upper end of section 152 of knife element 130. Referring to FIGS. 11 and 12, it will be seen that such engagement causes the knife element to rock about pin 164 so as to shear cut the wire section 50a. In the next step, the gripper 62 is released to free the knotted and tensioned wire tie. Specifically, the gripper operator element 232 carried by operator 218 is pivoted into engagement with oblique surface 306 of body 305 carried by block 300. Such engagement causes the body 300 to be pivoted over center about the axis defined by connecting pin 336 and against the bias of springs 332. Such over center pivoting is accommodated by the slots 319 formed in ears 302 (see FIG. 9). It will further be appreciated that during this over center travel of block 300, the pin 316 engages the section 296 of component 290 so as to move the latter toward block 191, past stop block 328. Because of the arcuate configuration of end 292, a rolling action occurs during gripper release, i.e., the end 292 “rolls” along the wire which avoids undue stress concentrations. Shortly after the gripper 62 is released, the cover 266 is moved upwardly so as to permit ejection of the knotted and tensioned wire tie. This occurs because of the interaction of the rocker blocks 242, 244 carried by the operators 220, 222, with the abutments 272, 274 carried by arms 268, 270. Such interaction causes the cover 266 to be shifted outwardly as depicted in FIGS. 15, 16 and 19, thereby fully opening passageway 194. Normally, the tension of the knotted wire tie is sufficient to cause the latter to rapidly eject of its own accord from the knotter assembly and to separate the sections of track 44. However, as a further measure, the ejector fingers 238, 240 (see FIGS. 15-16) pass through the slots 144, 146 to engage and positively eject (if needed) the knotted and tensioned wire tie from the passageway 194. Thus, the wire tie separates the wire-receiving plates of the entrance and ejection assemblies 54, 64 against the bias of the clips 124, 126, and 351, and also separates the spring-loaded sections of track 44. This allows the twisted wire bale to “snap” into place around the refuse bale. The device 46 then returns to its ready position for another tying sequence. This involves actuation of device 200 to retract piston rod 208. When this occurs, the gear 256 returns to its original position along with the components of operating assembly 198. The cover 266 resumes its normal position, under the influence of spring 286. The gripper 62 returns to its ready position by springs 332 causing the block 300 to shift back over center so that the gripper 62 again assumes the FIG. 21 release position. The device 46 is thus again ready to create a knotted and tensioned wire tie. A feature of the present invention is the provision of a knotter assembly cover 266 which can be readily shifted to a remote knotter access position (see FIG. 8) allowing easy replacement or repair (e.g. clearing) of the knotter assembly 56. In particular, when such replacement or repair is needed, it is only necessary to grasp the cover 266 and rotate it upwardly through an arc of at least 90° and more preferably at least 120° to the knotter access position of FIG. 8. It will be observed that during the course of this pivoting the spring 286 goes over center, and thus biases the cover to the remote position. Hence the spring 286 serves a dual purpose in the device 46. Moreover, because primary block 128 of assembly 56 is mounted to the frame plates 68, 70 by threaded connectors 151, it is a simple matter to remove the fasteners 153 and pivot the body through an arc of approximately 90° until the body assumes the FIG. 8 position. It will be noted that in this position there is ready access to the pinion assembly 132. This procedure can easily be reversed by pivoting the body 128 back downwardly to its original position and inserting and tightening the fasteners 153. The preferred forms of the invention described above are to be used as illustration only, and should not be utilized in a limiting sense in interpreting the scope of the present invention. Obvious modifications to the exemplary embodiments, as hereinabove set forth, could be readily made by those skilled in the art without departing from the spirit of the present invention. The inventors hereby state their intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of the present invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set forth in the following claims.

<SOH> BACKGROUND OF INVENTION <EOH>1. Field of the Invention The present invention is broadly concerned with wire strapping apparatus of the type used to apply knotted and tensioned wire ties to preformed bales such as compressed refuse bales. More particularly, the invention is concerned with such apparatus having features permitting quick and easy access to critical wire knotting components, so that the user may readily clear, repair and/or replace such components as necessary. 2. Description of the Prior Art Various wire tying and strapping machines have been proposed in the past for applying knotted and tensioned wire ties to bales, packages or other articles. One class of these prior machines makes us of a continuous, two-piece wire track with an associated strapping device. In such units, a package or bale to be tied is positioned within the confines of the wire track, and a continuous strand of wire is advanced completely around the track and overlapped with itself. The wire is then tensioned and the overlapped sections are knotted together by twisting. This further tensions the wire to the point that the track sections are separated allowing the knotted and tensioned tie to snap into place about the bale or article. In some cases more complex devices are provided for ejecting the knotted wire from the track. Commonly, a twister pinion is employed for twist-knotting of adjacent wire sections. Such a knotter pinion includes a slot to accommodate the wire sections and upon rotation of the pinion a defined number of turns or twists are created. In order to maintain the wires in the twister pinion and associated structure, a shiftable knotter cover located adjacent the twister pinion is used. A significant problem with prior machines is the difficulty of readily clearing or servicing the twister pinion and related structure. Hence, in one prior machine design, it is necessary to physically detach the cover and disassemble the pinion apparatus for servicing purposes. In other instances, the cover is movable to only a very limited extent, making it very difficult to access the pinion. Prior art patents relating to strapping devices include U.S. Pat. Nos. 4,777,554, 3,295,436, 2,922,359, and 4,817,519.

<SOH> SUMMARY OF INVENTION <EOH>The present invention overcomes the problems outlined above and provides an improved knotting device of the type including a rotatable knotter operable to twist-knot a pair of adjacent wire sections and having a cover located proximal to the knotter for maintaining the wire sections within the knotter during knotter operations. In particular, the improved device has a mount for the knotter cover permitting the cover to be pivoted away from the knotter to a knotter access position remote from the home or wire-maintaining position and through an arc of at least about 45°, more preferably greater than about 60°, and most advantageously around 90°. Preferably, the rotatable knotter is in the form of a slotted, rotatable pinion adapted to receive adjacent wire sections within the slot thereof, and the associated knotter cover is mounted on a leg pivotal about an access remote from the cover and generally parallel thereto. An over center spring is secured to the cover mount for biasing the cover to its home position, and also biasing the cover to its knotter access position when the cover is shifted away from the knotter. In further preferred forms of the invention, the rotatable knotter is mounted to an elongated, axially pivotal support body. The body is mounted to a stationary frame member by way of a threaded couplers or any convenient means. Thus, when the cover is in its remote position, it is a simple matter to loosen the threaded couplers and rotate the support body to a position facilitating access to rotatable knotter. In another aspect of the invention, a knotting device is provided having a knotting assembly comprising a gripper for selectively gripping one of two adjacent wire sections, a rotatable knotter operable to twist-knot the adjacent sections, a cutting element for cutting the other of the adjacent wire sections after twist-knotting of the sections, and a shiftable cover adjacent the knotter for obtaining the wire sections within the knotter during twist-knotting and thereafter movable to a wire-clearing position permitting passage of the twist-knotted wire sections from the knotter. In this case an operator assembly is provided for timed operation of the gripper, knotter, cutting element, and cover and a single drive assembly (e.g., a piston and cylinder assembly) is coupled with the operator assembly for effecting the timed operation. Use of only a single drive assembly makes it possible to mechanically time the knotting device on a very precise basis. This in turn facilitates and speeds up the overall wire tying sequence. Preferably, the operator assembly includes a pivotal shaft carrying respective mechanical operator bodies for the gripper, knotter, cutting element and cover.

20040414

20080520

20051020

61131.0

NGUYEN, JIMMY T

WIRE STRAPPER FOR WASTE MATERIAL BALER

SMALL

ACCEPTED

ACCEPTED

METHOD OF DETERMINING THE NUCLEOTIDE SEQUENCE OF OLIGONUCLEOTIDES AND DNA MOLECULES

The present invention relates to a novel method for analyzing nucleic acid sequences based on real-time detection of DNA poly-merase-catalyzed incorporation of each of the four nucleotide bases, supplied individually and serially in a microfluidic system, to a reaction cell containing a template system comprising a DNA fragment of unknown sequence and an oligonucleotide primer. Incorporation of a nucleotide base into the template system can be detected by any of a variety of methods including but not limited to fluorescence and chemiluminescence detection. Alternatively, microcalorimetic detection of the heat generated by the incorporation of a nucleotide into the extending template system using thermopile, thermistor and refractive index measurements can be used to detect extension reactions.

1. A method of DNA sequencing comprising the steps of: (a) providing a template system comprising at least one nucleic acid molecule of unknown sequence hybridized to a primer oligonucleotide in the presence of a DNA polymerase with reduced exonuclease activity; (b) contacting the template system with a single type of deoxyribonucleotide under conditions which allow extension of the primer by incorporation of at least one deoxyribonucleotide to the 3′ end of the primer to form an extended primer; (c) detecting whether extension of the primer has occurred; (d) detecting the number of deoxyribonucleotides incorporated into the primer; (e) removing unincorporated deoxyribonucleotide; and (f) repeating steps (a) through (e) to determine the nucleotide sequence of the nucleic acid molecule. 2. The method of claim 1 wherein the at least one deoxyribonucleotide includes a chemiluminescent moiety comprising detecting whether extension of the primer has occurred by detecting a chemiluminescent signal emitted by the chemiluminescent moiety, and further comprising removing the chemiluminescent moiety from the template system. 3. The method of claim 1 wherein the at least one deoxyribonucleotide includes a fluorescent moiety comprising detecting whether extension of the primer has occurred by detecting a fluorescent signal emitted by the fluorescent moiety, and further comprising removing the fluorescent moiety from the template system. 4. The method of claim 1 wherein the at least one deoxyribonucleotide includes a fluorescent moiety comprising detecting whether extension of the primer has occurred by detecting a fluorescent signal emitted by the fluorescent moiety, and further comprising destroying the fluorescent signal without removal of the fluorescent moiety. 5. The method of claim 4 wherein the fluorescent moiety is destroyed by reaction with compounds capable of extracting an electron from the excited state of the fluorescent moiety. 6. The method of claim 5 wherein the compound is a diphenyliodonium salt. 7. The method of claim 1 comprising detecting whether extension of the primer has occurred by detecting a change in the concentration of unincorporated deoxyribonucleotide. 8. The method of claim 1, wherein incorporation of the at least one deoxyribonucleotide generates heat, comprising detecting whether extension of the primer has occurred by detecting the heat generated by said incorporation. 9. The method of claim 8 wherein a thermopile is used to detect the generated heat. 10. The method of claim 8 wherein a thermistor is used to detect the generated heat. 11. The method of claim 1 wherein the template system further includes a buffer wherein incorporation of the at least one deoxyribonucleotide generates heat which is absorbed by said buffer and further comprising measuring the refractive index of the buffer. 12. The method of claim 1 comprising detecting whether extension of the primer has occurred by detecting the concentration of pyrophosphate released by addition of a deoxyribonucleotide to the 3′ end of the primer. 13. The method of claim 12 wherein the concentration of pyrophosphate is detected by hydrolyzing the pyrophosphate and measuring heat generated by hydrolysis of the pyrophosphate. 14. The method of claim 1 wherein the DNA polymerase is a T4 DNA polymerase with a substitution of amino acid residue Asp112 by Ala and Glu114 by Ala. 15. The method of claim 11 wherein the DNA polymerase further comprises a T4 DNA polymerase with a substitution of amino acid residue Ile417 by Val. 16. A method of DNA sequencing comprising the steps of: (a) providing a template system comprising at least one nucleic acid molecule of unknown sequence hybridized to a primer oligonucleotide in the presence of a exonuclease deficient DNA polymerase; (b) contacting the template system with a single type of deoxyribonucleotide under conditions which allow extension of the primer by incorporation of at least one deoxyribonucleotide to the 3′ end of the primer to form an extended primer; (c) detecting whether extension of the primer has occurred thereby identifying the deoxyribonucleotide added to the 3′ end of the primer; (d) detecting the number of deoxyribonucleotides incorporated into the primer; (e) removing unincorporated deoxyribonucleotide; (f) contacting the template system with a mixture including an exonuclease proficient DNA polymerase, an exonuclease deficient DNA polymerase and the identified deoxyribonucleotide of step (b); (g) removing the mixture of step (f); and (h) repeating steps (a) through (g) to determine the nucleotide sequence of the nucleic acid molecule. 17. The method of claim 16 wherein the at least one deoxyribonucleotide includes a flourescent moiety comprising detecting whether extension of the primer has occurred by detecting a fluorescent signal emitted by the fluorescent moiety. 18. The method of claim 16 wherein the at least one deoxyribonucleotide includes a fluorescent moiety comprising detecting whether extension of the primer has occurred by detecting a fluorescent signal emitted by the fluorescent moiety, and further comprising destroying the fluorescent signal without removal of the fluorescent moiety. 19. The method of claim 18 wherein the fluorescent moiety is destroyed by reaction with compounds capable of extracting an electron from the excited state of the fluorescent moiety. 20. The method of claim 19 wherein the compound is a diphenyliodonium salt. 21. The method of claim 16 wherein the at least one deoxyribonucleotide includes a chemiluminescent moiety comprising detecting whether extension of the primer has occurred by detecting chemiluminescent signal emitted by the chemiluminescent moiety. 22. The method of claim 16 comprising detecting whether extension of the primer has occurred by detecting a change in the concentration of unincorporated deoxyribonucleotide. 23. The method of claim 16 wherein incorporation of the at least one deoxyribonucleotide generates heat comprising detecting whether extension of the primer has occurred by detecting heat generated by said incorporation. 24. The method of claim 23 wherein a thermopile is used to detect the generated heat. 25. The method of claim 23 wherein a thermistor is used to detect the generated heat. 26. The method of claim 16 wherein the template system further includes a buffer wherein incorporation of the at least one deoxyribonucleotide generates heat which is absorbed by said buffer and further comprising measuring the refractive index of the buffer. 27. The method of claim 16 comprising detecting whether extension of the primer has occurred by detecting the concentration of pyrophosphate released by incorporation of a deoxyribonucleotide to the 3′ end of the primer. 28. The method of claim 27 wherein the concentration of pyrophosphate is detected by hydrolyzing the pyrophosphate and measuring the heat generated by hydrolysis of the pyrophosphate. 29. The method of claim 16 wherein the exonuclease deficient DNA polymerase is a T4 DNA polymerase with a substitution of amino acid residue Asp112 by Ala and Glu114 by Ala. 30. The method of claim 26 wherein the exonuclease deficient DNA polymerase further comprises a T4 DNA polymerase with a substitution of amino acid residue Ile417 by Val. 31. A method for removal of contaminating nucleotides from a solution comprising contacting said solution with immobilized DNA complementary to each of the three possibly contaminating nucleotides in the presence of primers and polymerase for a time sufficient to incorporate any contaminating nucleotides into DNA. 32. A method for discriminating between the in-phase and out-of-phase sequencing signals comprising: (a) detecting and measuring error signals thereby determining the size of the trailing strand population; (b) between the 3′ terminus of the trailing strand primers and the 3′ terminus of the leading strand primers; (c) simulating the occurrence of an extension failure at a point upstream from the 3′ terminus of the leading strands thereby predicting at each extension step the exact point in the sequence previously traversed by the leading strands to which the 3′ termini of the trailing strands have been extended; (d) predicting for each dNTP introduced the signal to be expected from correct extension of the trailing strands; and (e) subtracting the predicted signal from the measured signal to yield a signal due only to correct extension of the leading strand population.

CROSS REFERENCE TO RELATED APPLICATIONS This patent application is a continuation of Ser. No. 09/941,882 filed Aug. 28, 2001, which is a continuation-in-part of Ser. No. 09/673,544 filed Feb. 26, 2001 and now abandoned, which is a continuation-in-part of PCT/US99/09616 filed Apr. 30, 1999 and claims the benefit of provisional application Ser. No. 60/083,840 filed May 1, 1998. INTRODUCTION The present invention relates to a novel method for analyzing nucleic acid sequences based on real-time detection of DNA polymerase-catalyzed incorporation of each of the four deoxynucleoside monophosphates, supplied individually and serially as deoxynucleoside triphosphates in a micro fluidic system, to a template system comprising a DNA fragment of unknown sequence and an oligonucleotide primer. Incorporation of a deoxynucleoside-monophosphate (dNMP) into the primer can be detected by any of a variety of methods including but not limited to fluorescence and chemiluminescence detection. Alternatively, microcalorimetic detection of the heat generated by the incorporation of a dNMP into the extending primer using thermopile, thermistor and refractive index measurements can be used to detect extension reactions. The present invention further provides a method for monitoring and correction of sequencing errors due to misincorporation or extension failure. The present invention provides a method for sequencing DNA that avoids electrophoretic separation of DNA fragments thus eliminating the problems associated with anomalous migration of DNA due to repeated base sequences or other self-complementary sequences which can cause single-stranded DNA to self-hybridize into hairpin loops, and also avoids current limitations on the size of fragments that can be read. The method of the invention can be utilized to determine the nucleotide sequence of genomic or cDNA fragments, or alternatively, as a diagnostic tool for sequencing patient derived DNA samples. BACKGROUND OF INVENTION Currently, two approaches are utilized for DNA sequence determination: the dideoxy chain termination method of Sanger (1977, Proc. Natl. Acad. Sci 74:5463-5674) and the chemical degradation method of Maxam (1977, Proc. Natl. Acad. Sci 74:560-564). The Sanger dideoxy chain termination method is the most widely used method and is the method upon which automated DNA sequencing machines rely. In the chain termination method, DNA polymerase enzyme is added to four separate reaction systems to make multiple copies of a template DNA strand in which the growth process has been arrested at each occurrence of an A, in one set of reactions, and a G, C, or T, respectively, in the other sets of reactions, by incorporating in each reaction system one nucleotide type lacking the 3′-OH on the deoxyribose at which chain extension occurs. This procedure produces a series of DNA fragments of different lengths, and it is the length of the extended DNA fragment that signals the position along the template strand at which each of four bases occur. To determine the nucleotide sequence, the DNA fragments are separated by high resolution gel electrophoresis and the order of the four bases is read from the gel. A major research goal is to derive the DNA sequence of the entire human genome. To meet this goal the need has developed for new genomic sequencing technology that can dispense with the difficulties of gel electrophoresis, lower the costs of performing sequencing reactions, including reagent costs, increase the speed and accuracy of sequencing, and increase the length of sequence that can be read in a single step. Potential improvements in sequencing speed may be provided by a commercialized capillary gel electrophoresis technique such as that described in Marshall and Pennisis (1998, Science 280:994-995). However, a major problem common to all gel electrophoresis approaches is the occurrence of DNA sequence compressions, usually arising from secondary structures in the DNA fragment, which result in anomalous migration of certain DNA fragments through the gel. As genomic information accumulates and the relationships between gene mutations and specific diseases are identified, there will be a growing need for diagnostic methods for identification of mutations. In contrast to the large scale methods needed for sequencing large segments of the human genome, what is needed for diagnostic methods are repetitive, low-cost, highly accurate techniques for resequencing of certain small isolated regions of the genome. In such instances, methods of sequencing based on gel electrophoresis readout become far too slow and expensive. When considering novel DNA sequencing techniques, the possibility of reading the sequence directly, much as the cell does, rather than indirectly as in the Sanger dideoxynucleotide approach, is a preferred goal. This was the goal of early unsuccessful attempts to determine the shapes of the individual nucleotide bases with scanning probe microscopes. Additionally, another approach for reading a nucleotide sequence directly is to treat the DNA with an exonuclease coupled with a detection scheme for identifying each nucleotide sequentially released as described in Goodwin, et al., (1995, Experimental Techniques of Physics 41:279-294). However, researchers using this technology are confronted with the enormous problem of detecting and identifying single nucleotide molecules as they are digested from a single DNA strand. Simultaneous exonuclease digestion of multiple DNA strands to yield larger signals is not feasible because the enzymes rapidly get out of phase, so that nucleotides from different positions on the different strands are released together, and the sequences become unreadable. It would be highly beneficial if some means of external regulation of the exonuclease could be found so that multiple enzyme molecules could be compelled to operate in phase. However, external regulation of an enzyme that remains docked to its polymeric substrate is exceptionally difficult, if not impossible, because after each digestion the next substrate segment is immediately present at the active site. Thus, any controlling signal must be present at the active site at the start of each reaction. A variety of methods may be used to detect the poly-merase-catalyzed incorporation of deoxynucleoside monophosphates (dNMPs) into a primer at each template site. For example, the pyrophosphate released whenever DNA polymerase adds one of the four dNTPs onto a primer 3′ end may be detected using a chemiluminescent based detection of the pyrophosphate as described in Hyman E. D. (1988, Analytical Biochemistry 174:423-436) and U.S. Pat. No. 4,971,903. This approach has been utilized most recently in a sequencing approach referred to as “sequencing by incorporation” as described in Ronaghi (1996, Analytical Biochem. 242:84) and Ronaghi (1998, Science 281:363-365). However, there exist two key problems associated with this approach, destruction of unincorporated nucleotides and detection of pyrophosphate. The solution to the first problem is to destroy the added, unincorporated nucleotides using a dNTP-digesting enzyme such as apyrase. The solution to the second is the detection of the pyrophosphate using ATP sulfurylase to reconvert the pyrophosphate to ATP which can be detected by a luciferase chemiluminescent reaction as described in U.S. Pat. No. 4,971,903 and Ronaghi (1998, Science 281:363-365). Deoxyadenosine α-thiotriphosphate is used instead of dATP to minimize direct interaction of injected dATP with the luciferase. Unfortunately, the requirement for multiple enzyme reactions to be completed in each cycle imposes restrictions on the speed of this approach while the read length is limited by the impossibility of completely destroying un-incorporated, non-complementary, nucleotides. If some residual amount of one nucleotide remains in the reaction system at the time when a fresh aliquot of a different nucleotide is added for the next extension reaction, there exists a possibility that some fraction of the primer strands will be extended by two or more nucleotides, the added nucleotide type and the residual impurity type, if these match the template sequence, and so this fraction of the primer strands will then be out of phase with the remainder. This out of phase component produces an erroneous incorporation signal which grows larger with each cycle and ultimately makes the sequence unreadable. A different direct sequencing approach uses dNTPs tagged at the 3′ OH position with four different colored fluorescent tags, one for each of the four nucleotides is described in Metzger, M. L., et al. (1994, Nucleic Acids Research 22:4259-4267). In this approach, the primer/template duplex is contacted with all four dNTPs simultaneously. Incorporation of a 3′ tagged NMP blocks further chain extension. The excess and unreacted dNTPs are flushed away and the incorporated nucleotide is identified by the color of the incorporated fluorescent tag. The fluorescent tag must then be removed in order for a subsequent incorporation reaction to occur. Similar to the pyrophosphate detection method, incomplete removal of a blocking fluorescent tag leaves some primer strands unextended on the next reaction cycle, and if these are subsequently unblocked in a later cycle, once again an out-of-phase signal is produced which grows larger with each cycle and ultimately limits the read length. To date, this method has so far been demonstrated to work for only a single base extension. Thus, this method is slow and is likely to be restricted to very short read lengths due to the fact that 99% efficiency in removal of the tag is required to read beyond 50 base pairs. Incomplete removal of the label results in out of phase extended DNA strands. SUMMARY OF INVENTION Accordingly, it is an object of the present invention to provide a novel method for determining the nucleotide sequence of a DNA fragment which eliminates the need for electrophoretic separation of DNA fragments. The inventive method, referred to herein as “reactive sequencing”, is based on detection of DNA polymerase catalyzed incorporation of each of the four nucleotide types, when deoxynucleoside triphosphates (dNTP's) are supplied individually and serially to a DNA primer/template system. The DNA primer/template system comprises a single stranded DNA fragment of unknown sequence, an oligonucleotide primer that forms a matched duplex with a short region of the single stranded DNA, and a DNA polymerase enzyme. The enzyme may either be already present in the template system, or may be supplied together with the dNTP solution. Typically a single deoxynucleoside triphosphate (dNTP) is added to the DNA primer template system and allowed to react. As used herein deoxyribonucleotide means and includes, in addition to dGTP, dCTP, dATP, dTTP, chemically modified versions of these deoxyribonucleotides or analogs thereof. Such chemically modified deoxyribonucleotides include but are not limited to those deoxyribonucleotides tagged with a fluorescent or chemiluminescent moiety. Analogs of deoxyribonucleotides that may be used include but are not limited to 7-deazapurine. The present invention additionally provides a method for improving the purity of deoxynucleotides used in the polymerase reaction. An extension reaction will occur only when the incoming dNTP base is complementary to the next unpaired base of the DNA template beyond the 3′ end of the primer. While the reaction is occurring, or after a delay of sufficient duration to allow a reaction to occur, the system is tested to determine whether an additional nucleotide derived from the added dNTP has been incorporated into the DNA primer/template system. A correlation between the dNTP added to the reaction cell and detection of an incorporation signal identifies the nucleotide incorporated into the primer/template. The amplitude of the incorporation signal identifies the number of nucleotides incorporated, and thereby quantifies single base repeat lengths where these occur. By repeating this process with each of the four nucleotides individually, the sequence of the template can be directly read in the 5′ to 3′ direction one nucleotide at a time. Detection of the polymerase mediated extension reaction and quantification of the extent of reaction can occur by a variety of different techniques, including but not limited to, microcalorimetic detection of the heat generated by the incorporation of a nucleotide into the extending duplex. Optical detection of an extension reaction by fluorescence or chemiluminescence may also be used to detect incorporation of nucleotides tagged with fluorescent or chemiluminescent entities into the extending duplex. Where the incorporated nucleotide is tagged with a fluorophore, excess unincorporated nucleotide is removed, and the template system is illuminated to stimulate fluorescence from the incorporated nucleotide. The fluorescent tag may then be cleaved and removed from the DNA template system before a subsequent incorporation cycle begins. A similar process is followed for chemiluminescent tags, with the chemiluminescent reaction being stimulated by introducing an appropriate reagent into the system, again after excess unreacted tagged dNTP has been removed; however, chemiluminescent tags are typically destroyed in the process of readout and so a separate cleavage and removal step following detection may not be required. For either type of tag, fluorescent or chemiluminescent, the tag may also be cleaved after incorporation and transported to a separate detection chamber for fluorescent or chemiluminescent detection. In this way, fluorescent quenching by adjacent fluorophore tags incorporated in a single base repeat sequence may be avoided. In addition, this may protect the DNA template system from possible radiation damage in the case of fluorescent detection or from possible chemical damage in the case of chemiluminescent detection. Alternatively the fluorescent tag may be selectively destroyed by a chemical or photochemical reaction. This process eliminates the need to cleave the tag after each readout, or to detach and transport the tag from the reaction chamber to a separate detection chamber for fluorescent detection. The present invention provides a method for selective destruction of a fluorescent tag by a photochemical reaction with diphenyliodonium ions or related species. The present invention further provides a reactive sequencing method that utilizes a two cycle system. An exonuclease-deficient polymerase is used in the first cycle and a mixture of exonuclease-deficient and exonuclease-proficient enzymes are used in the second cycle. In the first cycle, the template-primer system together with an exonuclease-deficient polymerase will be presented sequentially with each of the four possible nucleotides. In the second cycle, after identification of the correct nucleotide, a mixture of exonuclease proficient and deficient polymerases, or a polymerase containing both types of activity will be added in a second cycle together with the correct dNTP identified in the first cycle to complete and proofread the primer extension. In this way, an exonuclease-proficient polymerase is only present in the reaction cell when the correct dNTP is present, so that exonucleolytic degradation of correctly extended strands does not occur, while degradation and correct re-extension of previously incorrectly extended strands does occur, thus achieving extremely accurate strand extension. The present invention also provides a method for monitoring reactive sequencing reactions to detect and correct sequencing reaction errors resulting from misincorporation, i.e., incorrectly incorporating a non-complementary base, and extension failure, i.e., failure to extend a fraction of the DNA primer strands. The method is based on the ability to (i) determine the size of the trailing strand population (trailing strands are those primer strands which have undergone an extension failure at any extension prior to the current reaction step); (ii) determine the downstream sequence of the trailing strand population between the 3′ terminus of the trailing strands and the 3′ terminus of the corresponding leading strands (“downstream” refers to the template sequence beyond the current 3′ terminus of a primer strand; correspondingly, “upstream” refers to the known template and complementary primer sequence towards the 5′ end of the primer strand; “leading strands” are those primer strands which have not previously undergone extension failure); and (iii) predict at each extension step the signal to be expected from the extension of the trailing strands through simulation of the occurrence of an extension failure at any point upstream from the 3′ terminus of the leading strand. Subtraction of the predicted signal from the measured signal yields a signal due only to valid extension of the leading strand population. In a preferred embodiment of the invention, the monitoring for reactive sequencing reaction errors is computer-aided. The ability to monitor extension failures permits determination of the point to which the trailing strands for a given template sequence have advanced and the sequence in the 1, 2 or 3 base gap between these strands and the leading strands. Knowing this information the dNTP probe cycle can be altered to selectively extend the trailing strands for a given template sequence while not extending the leading strands, thereby resynchronizing the populations. The present invention further provides an apparatus for DNA sequencing comprising: (a) at least one chamber including a DNA primer/template system which produces a detectable signal when a DNA polymerase enzyme incorporates a deoxyribonucleotide monophosphate onto the 3′ end of the primer strand; (b) means for introducing into, and evacuating from, the reaction chamber at least one selected from the group consisting of buffers, electrolytes, DNA template, DNA primer, deoxyribonucleotides, and polymerase enzymes; (c) means for amplifying said signal; and (d) means for converting said signal into an electrical signal. BRIEF DESCRIPTION OF DRAWINGS Further objects and advantages of the invention will be apparent from a reading of the following description in conjunction with the accompanying drawings, in which: FIG. 1 is a schematic diagram illustrating a reactive sequencing device containing a thin film bismuth antimony thermopile in accordance with the invention; FIG. 2 is a schematic diagram of a reactive sequencing device containing a thermistor in accordance with the invention; FIG. 3 is a schematic diagram illustrating a representative embodiment of micro calorimetry detection of a DNA polymerase reaction in accordance with the invention; FIG. 4 is an electrophoretic gel showing a time course for primer extension assays catalyzed by T4 DNA polymerase mutants; FIG. 5 is a schematic diagram illustrating a nucleotide attached to a fluorophore by a benzoin ester which is a photocleavable linker for use in the invention; FIG. 6 is a schematic illustration of a nucleotide attached to a chemiluminescent tag for use in the invention; FIG. 7 is a schematic diagram of a nucleotide attached to a chemiluminescent tag by a cleavable linkage; FIGS. 8(a) and 8(b) are schematic diagrams of a mechanical fluorescent sequencing method in accordance with the invention in which a DNA template and primer are absorbed on beads captured behind a porous frit; and FIG. 9 is a schematic diagram of a sequencing method in accordance with the invention utilizing a two cycle system. FIG. 10 is a diagram of the mechanism of photochemical degradation of fluorescein by diphenyliodonium ion (DPI). FIG. 11 shows fluorescence spectra of equimolar concentrations of fluorescein and tetramethylrhodamine dyes before and after addition of a solution of diphenyliodonium chloride. FIG. 12 is the UV absorption spectra obtained from (1) fluorescein and (2) fluorescein+DPI after a single flash from a xenon camera strobe. FIG. 13 displays the fluorescence spectra from single nucleotide polymerase reactions with DPI photobleaching between incorporation reactions. FIG. 14A-D. Simulation of Reactive Sequencing of [CTGA] GAA ACC AGA AAG TCC [T], probed with a dNTP cycle. 14A. Sequence readout close to the primer where no extension failure has occurred. 14B. Sequence readout downstream of primer where 60% of the strands have undergone extension failure and are producing out of phase signals and misincorporation has prevented extension on 75% of all strands. 14C. Downstream readout with error signals from trailing strands (dark shading) distinguished from correct readout signals from leading strands (light shading) using knowledge of the downstream sequence of the trailing strands. 14D. Corrected sequence readout following subtraction of error signals from trailing strands. Note the similarity to the data of FIG. 1A. FIG. 15. Effect of a leading strand population on extension signals. DETAILED DESCRIPTION The present invention provides a method for determining the nucleic acid sequence of a DNA molecule based on detection of successive single nucleotide DNA polymerase mediated extension reactions. As described in detail below, in one embodiment, a DNA primer/template system comprising a polynucleotide primer complementary to and bound to a region of the DNA to be sequenced is constrained within a reaction cell into which buffer solutions containing various reagents necessary for a DNA polymerase reaction to occur are added. Into the reaction cell, a single type of deoxynucleoside triphosphate (dNTP) is added. Depending on the identity of the next complementary site in the DNA primer/template system, an extension reaction will occur only when the appropriate nucleotide is present in the reaction cell. A correlation between the nucleotide present in the reaction cell and detection of an incorporation signal identifies the next nucleotide of the template. Following each extension reaction, the reaction cell is flushed with dNTP-free buffer, retaining the DNA primer/template system, and the cycle is repeated until the entire nucleotide sequence is identified. The present invention is based on the existence of a control signal within the active site of DNA polymerases which distinguish, with high fidelity, complementary and non-complementary fits of incoming deoxynucleotide triphosphates to the base on the template strand at the primer extension site, i.e., to read the sequence, and to incorporate at that site only the one type of deoxynucleotide that is complementary. That is, if the available nucleotide type is not complementary to the next template site, the polymerase is inactive, thus, the template sequence is the DNA polymerase control signal. Therefore, by contacting a DNA polymerase system with a single nucleotide type rather than all four, the next base in the sequence can be identified by detecting whether or not a reaction occurs. Further, single base repeat lengths can be quantified by quantifying the extent of reaction. As a first step in the practice of the inventive method, single-stranded template DNA to be sequenced is prepared using any of a variety of different methods known in the art. Two types of DNA can be used as templates in the sequencing reactions. Pure single-stranded DNA such as that obtained from recombinant bacteriophage can be used. The use of bacteriophage provides a method for producing large quantities of pure single stranded template. Alternatively, single-stranded DNA may be derived from double-stranded DNA that has been denatured by heat or alkaline conditions, as described in Chen and Subrung, (1985, DNA 4:165); Huttoi and Skaki (1986, Anal. Biochem. 152:232); and Mierendorf and Pfeffer, (1987, Methods Enzymol. 152:556), may be used. Such double stranded DNA includes, for example, DNA samples derived from patients to be used in diagnostic sequencing reactions. The template DNA can be prepared by various techniques well known to those of skill in the art. For example, template DNA can be prepared as vector inserts using any conventional cloning methods, including those used frequently for sequencing. Such methods can be found in Sambrook et al., Molecular Cloning: A Laboratory Manual, Second Edition (Cold Spring Harbor Laboratories, New York, 1989). In a preferred embodiment of the invention, polymerase chain reactions (PCR) may be used to amplify fragments of DNA to be used as template DNA as described in Innis et al., ed. PCR Protocols (Academic Press, New York, 1990). The amount of DNA template needed for accurate detection of the polymerase reaction will depend on the detection technique used. For example, for optical detection, e.g., fluorescence or chemiluminescence detection, relatively small quantities of DNA in the femtomole range are needed. For thermal detection quantities approaching one picomole may be required to detect the change in temperature resulting from a DNA polymerase mediated extension reaction. In enzymatic sequencing reactions, the priming of DNA synthesis is achieved by the use of an oligonucleotide primer with a base sequence that is complementary to, and therefore capable of binding to, a specific region on the template DNA sequence. In instances where the template DNA is obtained as single stranded DNA from bacteriophage, or as double stranded DNA derived from plasmids, “universal” primers that are complementary to sequences in the vectors, i.e.,the bacteriophage, cosmid and plasmid vectors, and that flank the template DNA, can be used. Primer oligonucleotides are chosen to form highly stable duplexes that bind to the template DNA sequences and remain intact during any washing steps during the extension cycles. Preferably, the length of the primer oligonucleotide is from 18-30 nucleotides and contains a balanced base composition. The structure of the primer should also be analyzed to confirm that it does not contain regions of dyad symmetry which can fold and self anneal to form secondary structures thereby rendering the primers inefficient. Conditions for selecting appropriate hybridization conditions for binding of the oligonucleotide primers in the template systems will depend on the primer sequence and are well known to those of skill in the art. In utilizing the reactive sequencing method of the invention, a variety of different DNA polymerases may be used to incorporate dNTPs onto the 3′ end of the primer which is hybridized to the template DNA molecule. Such DNA polymerases include but are not limited to Taq polymerase, T7 or T4 polymerase, and Klenow polymerase. In a preferred embodiment of the invention, described in detail below, DNA polymerases lacking 5′-3′-exonuclease proofreading activity are used in the sequencing reactions. For the most rapid reaction kinetics, the amount of polymerase is sufficient to ensure that each DNA molecule carries a non-covalently attached polymerase molecule during reaction. For a typical equilibrium constant of −50 nM for the dissociation equilibrium: DNA-Pol⇄DNA+Pol K˜50 nM the desired condition is: [Pol]≧50 nM+[DNA]. In addition, reverse transcriptase which catalyzes the synthesis of single stranded DNA from an RNA template may be utilized in the reactive sequencing method of the invention to sequence messenger RNA (mRNA). Such a method comprises sequentially contacting an RNA template annealed to a primer (RNA primer/template) with dNTPs in the presence of reverse transcriptase enzyme to determine the sequence of the RNA. Because mRNA is produced by RNA polymerase-catalyzed synthesis from a DNA template, and thus contains the sequence information of the DNA template strand, sequencing the mRNA yields the sequence of the DNA gene from which it was transcribed. Eukaryotic mRNAs have poly(A) tails and therefore the primer for reverse transcription can be an oligo(dT). Typically, it will be most convenient to synthesize the oligo(dT) primer with a terminal biotin or amino group through which the primer can be captured on a substrate and subsequently hybridize to and capture the template mRNA strand. The extension reactions are carried out in buffer solutions which contain the appropriate concentrations of salts, dNTPs and DNA polymerase required for the DNA polymerase mediated extension to proceed. For guidance regarding such conditions see, for example, Sambrook, et al., (1989, Molecular Cloning, A Laboratory Manual, Cold Spring Harbor Press, N.Y.); and Ausubel, et al. (1989, Current Protocols in Molecular Biology, Green Publishing Associates and Wiley lnterscience, N.Y. ). Typically, buffer containing one of the four dNTPs is added into a reaction cell. Depending on the identity of the nucleoside base at the next unpaired template site in the primer/template system, a reaction will occur when the reaction cell contains the appropriate dNTP. When the reaction cell contains any one of the other three incorrect dNTPs, no reaction will take place. The reaction cell is then flushed with dNTP free buffer and the cycle is repeated until a complete DNA sequence is identified. Detection of a DNA polymerase mediated extension can be made using any of the detection methods described in detail below including optical and thermal detection of an extension reaction. In some instances, a nucleotide solution is found to be contaminated with any of the other three nucleotides. In such instances a small fraction of strands may be extended by incorporation of an impurity dNTP when the dNTP type supplied is incorrect for extension, producing a population of strands which are subsequently extended ahead of the main strand population. Thus, in an embodiment of the invention, each nucleotide solution can be treated to remove any contaminated nucleotides. Treatment of each nucleotide solution involves reaction of the solution prior to use with immobilized DNA complementary to each the possibly contaminating nucleotides. For example, a dATP solution will be allowed to react with immobilized poly (dA), poly (dG) or poly (dC), with appropriate primers and polymerase, for a time sufficient to incorporate any contaminating dTTP, dCTP and dGTP nucleotides into DNA. In a preferred embodiment of the invention, the primer/template system comprises the template DNA tethered to a solid phase support to permit the sequential addition of sequencing reaction reagents without complicated and time consuming purification steps following each extension reaction. Preferably, the template DNA is covalently attached to a solid phase support, such as the surface of a reaction flow cell, a polymeric microsphere, filter material, or the like, which permits the sequential application of sequencing reaction reagents, i.e., buffers, dNTPs and DNA polymerase, without complicated and time consuming purification steps following each extension reaction. Alternatively, for applications that require sequencing of many samples containing the same vector template or same gene, for example, in diagnostic applications, a universal primer may be tethered to a support, and the template DNA allowed to hybridize to the immobilized primer. The DNA may be modified to facilitate covalent or non-covalent tethering of the DNA to a solid phase support. For example, when PCR is used to amplify DNA fragments, the 5′ ends of one set of PCR primer oligonucleotides strands may be modified to carry a linker moiety for tethering one of the two complementary types of DNA strands produced to a solid phase support. Such linker moieties include, for example, biotin. When using biotin, the biotinylated DNA fragments may be bound non-covalently to streptavidin covalently attached to the solid phase support. Alternatively, an amino group (—NH2) may be chemically incorporated into one of the PCR primer strands and used to covalently link the DNA template to a solid phase support using standard chemistry, such as reactions with N-hydroxysuccinimide activated agarose surfaces. In another embodiment, the 5′ ends of the sequencing oligonucleotide primer may be modified with biotin, for non-covalent capture to a streptavidin-treated support, or with an amino group for chemical linkage to a solid support; the template strands are then captured by the non-covalent binding attraction between the immobilized primer base sequence and the complementary sequence on the template strands. Methods for immobilizing DNA on a solid phase support are well known to those of skill in the art and will vary depending on the solid phase support chosen. In the reactive sequencing method of the present invention, DNA polymerase is presented sequentially with each of the 4 dNTPs. In the majority of the reaction cycles, only incorrect dNTPs will be present, thereby increasing the likelihood of misincorporation of incorrect nucleotides into the extending DNA primer/template system. Accordingly, the present invention further provides methods for optimizing the reactive sequencing reaction to achieve rapid and complete incorporation of the correct nucleotide into the DNA primer/template system, while limiting the misincorporation of incorrect nucleotides. For example, dNTP concentrations may be lowered to reduce misincorporation of incorrect nucleotides into the DNA primer. Km values for incorrect dNTPs can be as much as 1000-fold higher than for correct nucleotides, indicating that a reduction in dNTP concentrations can reduce the rate of misincorporation of nucleotides. Thus, in a preferred embodiment of the invention the concentration of dNTPs in the sequencing reactions are approximately 5-20 μM. At this concentration, incorporation rates are as close to the maximum rate of 400 nucleotides/s for T4 DNA polymerase as possible. In addition, relatively short reaction times can be used to reduce the probability of misincorporation. For an incorporation rate approaching the maximum rate of 400 nucleotides/s, a reaction time of approximately 25 milliseconds (ms) will be sufficient to ensure extension of 99.99% of primer strands. In a specific embodiment of the invention, DNA polymerases lacking 3′ to 5′ exonuclease activity may be used for reactive sequencing to limit exonucleolytic degradation of primers that would occur in the absence of correct dNTPs. In the presence of all four dNTPs, misincorporation frequencies by DNA polymerases possessing exonucleolytic proofreading activity are as low as one error in 106 to 108 nucleotides incorporated as discussed in Echols and Goodman (1991, Annu. Rev. Biochem 60;477-511); and Goodman, et al. (1993, Crit. Rev. Biochem. Molec. Biol. 28:83-126); and Loeb and Kunkel (1982, Annu. Rev. Biochem. 52:429-457). In the absence of proofreading, DNA polymerase error rates are typically on the order of 1 in 104 to 1 in 106. Although exonuclease activity increases the fidelity of a DNA polymerase, the use of DNA polymerases having proofreading activity can pose technical difficulties for the reactive sequencing method of the present invention. Not only will the exonuclease remove any misincorporated nucleotides, but also, in the absence of a correct dNTP complementary to the next template base, the exonuclease will remove correctly-paired nucleotides successively until a point on the template sequence is reached where the base is complementary to the dNTP in the reaction cell. At this point, an idling reaction is established where the polymerase repeatedly incorporates the correct dNMP and then removes it. Only when a correct dNTP is present will the rate of polymerase activity exceed the exonuclease rate so that an idling reaction is established that maintains the incorporation of that correct nucleotide at the 3′ end of the primer. A number of T4 DNA polymerase mutants containing specific amino acid substitutions possess reduced exonuclease activity levels up to 10,000-fold less than the wild-type enzyme. For example, Reha-Krantz and Nonay (1993, J. Biol. Chem. 268:27100-17108) report that when Asp 112 was replaced with Ala and Glu 114 was replaced with Ala (D112A/E114A) in T4 polymerase, these two amino acid substitutions reduced the exonuclease activity on double stranded DNA by a factor of about 300 relative to the wild type enzyme. Such mutants may be advantageously used in the practice of the invention for incorporation of nucleotides into the DNA primer/template system. In yet another embodiment of the invention, DNA polymerases which are more accurate than wild type polymerases at incorporating the correct nucleotide into a DNA primer/template may be used. For example, in a (D112A/E114A) mutant T4 polymerase with a third mutation where Ile 417 is replaced by Val (1417V/D112A/E114A), the 1417V mutation results in an antimutator phenotype for the polymerase (Reha-Krantz and Nonay, 1994,J. Biol. Chem. 269:5635-5643; Stocki et al., 1995, Mol. Biol. 254:15-28). This antimutator phenotype arises because the polymerase tends to move the primer ends from the polymerase site to the exonuclease site more frequently and thus proof read more frequently than the wild type polymerase, and thus increases the accuracy of synthesis. In yet another embodiment of the invention, polymerase mutants that are capable of more efficiently incorporating fluorescent-labeled nucleotides into the template DNA system molecule may be used in the practice of the invention. The efficiency of incorporation of fluorescent-labeled nucleotides may be reduced due to the presence of bulky fluorophore labels that may inhibit dNTP interaction at the active site of the polymerase. Polymerase mutants that may be advantageously used for incorporation of fluorescent-labeled dNTPs into DNA include but are not limited to those described in U.S. application Ser. No. 08/632,742 filed Apr. 16, 1996 which is incorporated by reference herein. In a preferred embodiment of the invention, the reactive sequencing method utilizes a two cycle system. An exonuclease-deficient polymerase is used in the first cycle and a mixture of exonuclease-deficient and exonuclease-proficient enzymes are used in the second cycle. In the first cycle, the primer/template system together with an exonuclease-deficient polymerase will be presented sequentially with each of the four possible nucleotides. Reaction time and conditions will be such that a sufficient fraction of primers are extended to allow for detection and quantification of nucleotide incorporation, ˜98%, for accurate quantification of multiple single-base repeats. In the second cycle, after identification of the correct nucleotide, a mixture of exonuclease proficient and deficient polymerases, or a polymerase containing both types of activity will be added in a second cycle together with the correct dNTP identified in the first cycle to complete and proofread the primer extension. In this way, an exonuclease-proficient polymerase is only present in the reaction cell when the correct dNTP is present, so that exonucleolytic degradation of correctly extended strands does not occur, while degradation and correct re-extension of previously incorrectly extended strands does occur, thus achieving extremely accurate strand extension. The detection of a DNA polymerase mediated extension reaction can be accomplished in a number of ways. For example, the heat generated by the extension reaction can be measured using a variety of different techniques such as those employing thermopile, thermistor and refractive index measurements. In an embodiment of the invention, the heat generated by a DNA polymerase mediated extension reaction can be measured. For example, in a reaction cell volume of 100 micrometers3 containing 1 μg of water as the sole thermal mass and 2×1011 DNA template molecules (300 fmol) tethered within the cell, the temperature of the water increases by 1×10−3° C. for a polymerase reaction which extends the primer by a single nucleoside monophosphate. This calculation is based on the experimental determination that a one base pair extension in a DNA chain is an exothermic reaction and the enthalpy change associated with this reaction is 3.5 kcal/mole of base. Thus extension of 300 fmol of primer strands by a single base produces 300 fmol×3.5 kcal/mol or 1×10−9 cal of heat. This is sufficient to raise the temperature of 1 μg of water by 1×10−3° C. Such a temperature change can be readily detectable using thermistors (sensitivity ≦10° C.); thermopiles (sensitivity ≦10−5° C.); and refractive index measurements (sensitivity ≦10° C). In a specific embodiment of the invention, thermopiles may be used to detect temperature changes. Such thermopiles are known to have a high sensitivity to temperature and can make measurements in the tens of microdegree range in several second time constants. Thermopiles may be fabricated by constructing serial sets of junctions of two dissimilar metals and physically arranging the junctions so that alternating junctions are separated in space. One set of junctions is maintained at a constant reference temperature, while the alternate set of junctions is located in the region whose temperature is to be sensed. A temperature difference between the two sets of junctions produces a potential difference across the junction set which is proportional to the temperature difference, to the thermoelectric coefficient of the junction and to the number of junctions. For optimum response, bimetallic pairs with a large thermoelectric coefficient are desirable, such as bismuth and antimony. Thermopiles may be fabricated using thin film deposition techniques in which evaporated metal vapor is deposited onto insulating substrates through specially fabricated masks. Thermopiles that may be used in the practice of the invention include thermopiles such as those described in U.S. Pat. No. 4,935,345, which is incorporated by reference herein. In a specific embodiment of the invention, miniature thin film thermopiles produced by metal evaporation techniques, such as those described in U.S. Pat. No. 4,935,345 incorporated herein by reference, may be used to detect the enthalpy changes. Such devices have been made by vacuum evaporation through masks of about 10 mm square. Using methods of photolithography, sputter etching and reverse lift-off techniques, devices as small as 2 mm square may be constructed without the aid of modern microlithographic techniques. These devices contain 150 thermoelectric junctions and employ 12 micron line widths and can measure the exothermic heat of reaction of enzyme-catalyzed reactions in flow streams where the enzyme is preferably immobilized on the surface of the thermopile. To incorporate thermopile detection technology into a reactive sequencing device, thin-film bismuth-antimony thermopiles 2, as shown in FIG. 1, may be fabricated by successive electron-beam evaporation of bismuth and antimony metals through two different photolithographically-generated masks in order to produce a zigzag array of alternating thin bismuth and antimony wires which are connected to form two sets of bismuth-antimony thermocouple junctions. Modern microlithographic techniques will allow fabrication of devices at least one order of magnitude smaller than those previously made, i.e., with line widths as small as 1 ÿm and overall dimensions on the order of 100 μm2. One set of junctions 4 (the sensor junctions) is located within the reaction cell 6, i.e., deposited on a wall of the reaction cell, while the second reference set of junctions 8 is located outside the cell at a reference point whose temperature is kept constant. Any difference in temperature between the sensorjunctions and the reference junctions results in an electric potential being generated across the device, which can be measured by a high-resolution digital voltmeter 10 connected to measurement points 12 at either end of the device. It is not necessary that the temperature of the reaction cell and the reference junctions be the same in the absence of a polymerase reaction event, only that a change in the temperature of the sensorjunctions due to a polymerase reaction event be detectable as a change in the voltage generated across the thermopile. In addition to thermopiles, as shown in FIG. 2, a thermistor 14 may also be used to detect temperature changes in the reaction cell 6 resulting from DNA polymerase mediated incorporation of dNMPs into the DNA primer strand. Thermistors are semiconductors composed of a sintered mixture of metallic oxides such as manganese, nickel, and cobalt oxides. This material has a large temperature coefficient of resistance, typically ˜4% per ° C., and so can sense extremely small temperature changes when the resistance is monitored with a stable, high-resolution resistance-measuring device such as a digital voltmeter, e.g., Keithley Instruments Model 2002. A thermistor 14, such as that depicted in FIG. 2, may be fabricated in the reactive sequencing reaction cell by sputter depositing a thin film of the active thermistor material onto the surface of the reaction cell from a single target consisting of hot pressed nickel, cobalt and manganese oxides. Metal interconnections 16 which extend out beyond the wall of the reaction cell may also be fabricated in a separate step so that the resistance of the thermistor may be measured using an external measuring device 18. Temperature changes may also be sensed using a refractive index measurement technique. For example, techniques such as those described in Bornhop (1995, Applied Optics 34:3234-323) and U.S. Pat. No. 5,325,170, may be used to detect refractive index changes for liquids in capillaries. In such a technique, a low-power He—Ne laser is aimed off-center at a right angle to a capillary and undergoes multiple internal reflection. Part of the beam travels through the liquid while the remainder reflects only off the external capillary wall. The two beams undergo different phase shifts depending on the refractive index difference between the liquid and capillary. The result is an interference pattern, with the fringe position extremely sensitive to temperature—induced refractive index changes. In a further embodiment of the invention, the thermal response of the system may be increased by the presence of inorganic pyrophosphatase enzyme which is contacted with the template system along with the dNTP solution. Additionally, heat is released as the pyrophosphate released from the dNTPs upon incorporation into the template system is hydrolyzed by inorganic pyrophosphatase enzyme. In another embodiment, the pyrophosphate released upon incorporation of dNTP's may be removed from the template system and hydrolyzed, and the resultant heat detected, using thermopile, thermistor or refractive index methods, in a separate reaction cell downstream. In this reaction cell, inorganic pyrophosphatase enzyme may be mixed in solution with the dNTP removed from the DNA template system, or alternatively the inorganic pyrophosphatase enzyme may be covalently tethered to the wall of the reaction cell. Alternatively, the polymerase-catalyzed incorporation of a nucleotide base can be detected using fluorescence and chemiluminescence detection schemes. The DNA polymerase mediated extension is detected when a fluorescent or chemiluminescent signal is generated upon incorporation of a fluorescently or chemiluminescently labeled dNMP into the extending DNA primer strand. Such tags are attached to the nucleotide in such a way as to not interfere with the action of the polymerase. For example, the tag may be attached to the nucleotide base by a linker arm sufficiently long to move the bulky fluorophore away from the active site of the enzyme. For use of such detection schemes, nucleotide bases are labeled by covalently attaching a compound such that a fluorescent or chemiluminescent signal is generated following incorporation of a dNTP into the extending DNA primer/template. Examples of fluorescent compounds for labeling dNTPs include but are not limited to fluorescein, rhodamine, and BODIPY (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene). See “Handbook of Molecular Probes and Fluorescent Chemicals”, available from Molecular Probes, Inc. (Eugene, Oreg.). Examples of chemiluminescence based compounds that may be used in the sequencing methods of the invention include but are not limited to luminol and dioxetanones (See, Gundennan and McCapra, “Chemiluminescence in Organic Chemistry”, Springer-Verlag, Berlin Heidleberg, 1987) Fluorescently or chemiluminescently labeled dNTPs are added individually to a DNA template system containing template DNA annealed to the primer, DNA polymerase and the appropriate buffer conditions. After the reaction interval, the excess dNTP is removed and the system is probed to detect whether a fluorescent or chemiluminescent tagged nucleotide has been incorporated into the DNA template. Detection of the incorporated nucleotide can be accomplished using different methods that will depend on the type of tag utilized. For fluorescently-tagged dNTPs the DNA template system may be illuminated with optical radiation at a wavelength which is strongly absorbed by the tag entity. Fluorescence from the tag is detected using for example a photodetector together with an optical filter which excludes any scattered light at the excitation wavelength. Since labels on previously incorporated nucleotides would interfere with the signal generated by the most recently incorporated nucleotide, it is essential that the fluorescent tag be removed at the completion of each extension reaction. To facilitate removal of a fluorescent tag, the tag may be attached to the nucleotide via a chemically or photochemically cleavable linker using methods such as those described by Metzger, M. L., et al. (1994, Nucleic Acids Research 22:4259-4267) and Burgess, K., et al., (1997, J. Org. Chem. 62:5165-5168) so that the fluorescent tag may be removed from the DNA template system before a new extension reaction is carried out. In a further embodiment utilizing fluorescent detection, the fluorescent tag is attached to the dNTP by a photo-cleavable or chemically cleavable linker, and the tag is detached following the extension reaction and removed from the template system into a detection cell where the presence, and the amount, of the tag is determined by optical excitation at a suitable wavelength and detection of fluorescence. In this embodiment, the possibility of fluorescence quenching, due to the presence of multiple fluorescent tags immediately adjacent to one another on a primer strand which has been extended complementary to a single base repeat region in the template, is minimized, and the accuracy with which the repeat number can be determined is optimized. In addition, excitation of fluorescence in a separate chamber minimizes the possibility of photolytic damage to the DNA primer/template system. In an additional embodiment utilizing fluorescent detection, the signal from the fluorescent tag can be destroyed using a chemical reaction which specifically targets the fluorescent moiety and reacts to form a final product which is no longer fluorescent. In this embodiment, the fluorescent tag attached to the nucleotide base is destroyed following extension and detection of the fluorescence signal, without the removal of the tag. In a specific embodiment, fluorophores attached to dNTP bases may be selectively destroyed by reaction with compounds capable of extracting an electron from the excited state of the fluorescent moiety thereby producing a radical ion of the fluorescent moiety which then reacts to form a final product which is no longer fluorescent. In a further specific embodiment, the signal from a fluorescent tag is destroyed by photochemical reaction with the cation of a diphenyliodonium salt following extension and detection of the fluorescence label. The fluorescent tag attached to the incorporated nucleotide base is destroyed, without removal of the tag, by the addition of a solution of a diphenyliodonium salt to the reaction cell and subsequent UV light exposure. The diphenyliodonium salt solution is removed and the reactive sequencing is continued. This embodiment does not require dNTP's with chemically or photochemically cleavable linkers, since the fluorescent tag need not be removed. In a further embodiment of the technique, the response generated by a DNA polymerase-mediated extension reaction can be amplified. In this embodiment, the dNTP is chemically modified by the covalent attachment of a signaling tag through a linker that can be cleaved either chemically or photolytically. Following exposure of the dNTP to the primer/template system and flushing away any unincorporated chemically modified dNTP, any signaling tag that has been incorporated is detached by a chemical or photolytic reaction and flushed out of the reaction chamber to an amplification chamber in which an amplified signal may be produced and detected. A variety of methods may be used to produce an amplified signal. In one such method the signaling tag has a catalytic function. When the catalytic tag is cleaved and allowed to react with its substrate, many cycles of chemical reaction ensue producing many moles of product per mole of catalytic tag, with a corresponding multiplication of reaction enthalpy. Either the reaction product is detected, through some property such as color or absorbency, or the amplified heat product is detected by a thermal sensor. For example, if an enzyme is covalently attached to the dNTP via a cleavable linker arm of sufficient length that the enzyme does not interfere with the active site of the polymerase enzyme. Following incorporation onto the DNA primer strand, that enzyme is detached and transported to a second reactor volume in which it is allowed to interact with its specific substrate, thus an amplified response is obtained as each enzyme molecule carries out many cycles of reaction. For example, the enzyme catalase (CAT) catalyzes the reaction: If each dNTP is tagged with a catalase molecule which is detached after dNMP incorporation and allowed to react downstream with hydrogen peroxide, each nucleotide incorporation would generate ˜25 kcal/mol×N of heat where N is the number of hydrogen peroxide molecules decomposed by the catalase. The heat of decomposition of hydrogen peroxide is already ˜6-8 times greater than for nucleotide incorporation, (i.e. 3.5-4 kcal/mol). For decomposition of 150 hydrogen peroxide molecules the amount of heat generated per base incorporation approaches 1000 times that of the unamplified reaction. Similarly, enzymes which produce colored products, such as those commonly used in enzyme-linked immunosorbent assays (ELISA) could be incorporated as detachable tags. For example the enzyme alkaline phosphatase converts colorless p-nitrophenyl phosphate to a colored product (p-nitrophenol); the enzyme horseradish peroxidase converts colorless o-phenylenediamine hydrochloride to an orange product. Chemistries for linking these enzymes to proteins such as antibodies are well-known to those versed in the art, and could be adapted to link the enzymes to nucleotide bases via linker arms that maintain the enzymes at a distance from the active site of the polymerase enzymes. In a further embodiment, an amplified thermal signal may be produced when the signaling tag is an entity which can stimulate an active response in cells which are attached to, or held in the vicinity of, a thermal sensor such as a thermopile or thermistor. Pizziconi and Page (1997, Biosensors and Bioelectronics 12:457-466) reported that harvested and cultured mast cell populations could be activated by calcium ionophore to undergo exocytosis to release histamine, up to 10-30 pg (100-300 fmol) per cell. The multiple cell reactions leading to exocytosis are themselves exothermic. This process is further amplified using the enzymes diamine oxidase to oxidize the histamine to hydrogen peroxide and imidazoleacetaldehyde, and catalase to disproportionate the hydrogen peroxide. Two reactions together liberate over 100 kJ of heat per mole of histamine. For example, a calcium ionophore is covalently attached to the dNTP base via a linker arm which distances the linked calcium ionophore from the active site of the polymerase enzyme and is chemically or photochemically cleavable. Following the DNA polymerase catalyzed incorporation step, and flushing away unincorporated nucleotides any calcium ionophore remaining bound to an incorporated nucleotide may be cleaved and flushed downstream to a detection chamber containing a mast cell-based sensor such as described by Pizziconi and Page (1997, Biosensors and Bioelectronics 12:457-466). The calcium ionophore would bind to receptors on the mast cells stimulating histamine release with the accompanying generation of heat. The heat production could be further amplified by introducing the enzymes diamine oxidase to oxidize the histamine to hydrogen peroxide and imidazoleacetaldehyde, and catalase to disproportionate the hydrogen peroxide. Thus a significantly amplified heat signal would be produced which could readily be detected by a thermopile or thermistor sensor within, or in contact with, the reaction chamber. In a further embodiment utilizing chemiluminescent detection, the chemiluminescent tag is attached to the dNTP by a photocleavable or chemically cleavable linker. The tag is detached following the extension reaction and removed from the template system into a detection cell where the presence, and the amount, of the tag is determined by an appropriate chemical reaction and sensitive optical detection of the light produced. In this embodiment, the possibility of a non-linear optical response due to the presence of multiple chemiluminescent tags immediately adjacent to one another on a primer strand which has been extended complementary to a single base repeat region in the template, is minimized, and the accuracy with which the repeat number can be determined is optimized. In addition, generation of chemiluminescence in a separate chamber minimizes chemical damage to the DNA primer/template system, and allows detection under harsh chemical conditions which otherwise would chemically damage the DNA primer/template. In this way, chemiluminescent tags can be chosen to optimize chemiluminescence reaction speed, or compatibility of the tagged dNTP with the polymerase enzyme, without regard to the compatibility of the chemiluminescence reaction conditions with the DNA primer/template. In a further embodiment of the invention, the concentration of the dNTP solution removed from the template system following each extension reaction can be measured by detecting a change in UV absorption due to a change in the concentration of dNTPs, or a change in fluorescence response of fluorescently-tagged dNTPs. The incorporation of nucleotides into the extended template would result in a decreased concentration of nucleotides removed from the template system. Such a change could be detected by measuring the UV absorption of the buffer removed from the template system following each extension cycle. In a further embodiment of the invention, extension of the primer strand may be sensed by a device capable of sensing fluorescence from, or resolving an image of, a single DNA molecule. Devices capable of sensing fluorescence from a single molecule include the confocal microscope and the near-field optical microscope. Devices capable of resolving an image of a single molecule include the scanning tunneling microscope (STM) and the atomic force microscope (AFM). In this embodiment of the invention, a single DNA template molecule with attached primer is immobilized on a surface and viewed with an optical microscope or an STM or AFM before and after exposure to buffer solution containing a single type of dNTP, together with polymerase enzyme and other necessary electrolytes. When an optical microscope is used, the single molecule is exposed serially to fluorescently-tagged dNTP solutions and as before incorporation is sensed by detecting the fluorescent tag after excess unreacted dNTP is removed. Again as before, the incorporated fluorescent tag must be cleaved and discarded before a subsequent tag can be detected. Using the STM or AFM, the change in length of the primer strand is imaged to detect incorporation of the dNTP. Alternatively the dNTP may be tagged with a physically bulky molecule, more readily visible in the STM or AFM, and this bulky tag is removed and discarded before each fresh incorporation reaction. When sequencing a single molecular template in this way, the possibility of incomplete reaction producing erroneous signal and out-of-phase strand extension, does not exist and the consequent limitations on read length do not apply. For a single molecular template, reaction either occurs or it does not, and if it does not, then extension either ceases and is known to cease, or correct extension occurs in a subsequent cycle with the correct dNTP. In the event that an incorrect nucleotide is incorporated, which has the same probability as more the multiple strand processes discussed earlier, for example 1 in 1,000, an error is recorded in the sequence, but this error does not propagate or affect subsequent readout and so the read length is not limited by incorrect incorporation. Detection and Compensation for DNA Polymerase Errors In the reactive sequencing process, extension failures will typically arise due to the kinetics of the extension reaction and limitations on the amount of time allotted for each extension trial with the single deoxynucleotide triphosphates (dNTP's). When reaction is terminated by flushing away the dNTP supply, some small fraction of the primer strands may remain unextended. These strands on subsequent dNTP reaction cycles will continue to extend but will be out of phase with the majority strands, giving rise to small out-of-phase signals (i.e. signaling a positive incorporation for an added dNTP which is incorrect for extension of the majority strands). Because extension failure can occur, statistically, on any extension event, these out-of-phase signals will increase as the population of strands with extension failures grows. Ultimately the out-of-phase signal becomes comparable in amplitude with the signal due to correct extension of the majority strands and the sequence may be unreadable. The length by which the primer has been extended when the sequence becomes unreadable is known as the sequencing read length. The present invention relates to a method that can extend the sequencing read length in two ways, first, by discriminating between the in-phase and out-of-phase signals, and second by calculating where, and how, a dNTP probe sequence can be altered so as selectively to extend the out-of-phase strands to bring them back into phase with the majority strands. Specifically, a method is provided for discriminating between the in-phase and out-of-phase sequencing signals comprising: (i) detecting and measuring error signals thereby determining the size of the trailing strand population; (ii) between the 3′ terminus of the trailing strand primers and the 3′ terminus of the leading strand primers; (iii) simulating the occurrence of an extension failure at a point upstream from the 3′ terminus of the leading strands thereby predicting at each extension step the exact point in the sequence previously traversed by the leading strands to which the 3′ termini of the trailing strands have been extended; (iv) predicting for each dNTP introduced the signal to be expected from correct extension of the trailing strands; and (v) subtracting the predicted signal from the measured signal to yield a signal due only to correct extension of the leading strand population. “Upstream” refers to the known sequence of bases correctly incorporated onto the primer strands. “Down-stream” refers to the sequence beyond the 3′ terminus. Thus for the leading strand population the downstream sequence is unknown but is predetermined by the sequence of the template strand that has not yet been read; for the trailing strand population, the downstream sequence is known for the gap between the 3′ termini of the trailing and leading strands. The gap between the leading and trailing primer strands may be 1, 2 or 3 bases (where a single base repeat of any length, e.g. AAAA, is counted as a single base because the entire repeat will be traversed in a single reaction cycle if the correct dNTP is introduced), but can never exceed 3 bases nor shrink spontaneously to zero if the reaction cycle of the four dNTP's is unchanged and no other reaction errors occur, for example a second extension failure on the same primer strand. If the reaction cycle of the four dNTP's is unchanged, it may readily be understood that a primer strand which has failed to extend when the correct dNTP, for example dATP, is in the reaction chamber cannot trail the leading (majority) strands (which did extend) by more than 3 bases, because the fourth base in the dNTP reaction cycle will always once again be the correct base (dATP) for the strand which failed to extend previously. Similarly, a trailing strand resulting from an extension failure can never re-synchronize with the leading strands if extension subsequently proceeds correctly, because the leading strands will always have extended by at least one more nucleotide —G, T, or C in the example discussion of an A extension failure—before the trailing strand can add the missing A. The effect is that after each complete dNTP cycle the trailing strands always follow the leading strands by an extension amount that represents the bases added in one complete dNTP cycle at a given point in the sequence. A further consequence is that all trailing strands that have undergone a single failure are in phase with each other regardless of the point at which the extension failure occurred. The methods described herein may be utilized to significantly extend the read length that can be achieved by the technique of reactive sequencing by providing a high level of immunity to erroneous signals arising from extension failure. In a preferred embodiment of the invention, the discrimination method of the invention is computer based. First, determination of the readout signals allows real-time discrimination between the signals due to correct extension of the leading strand population and error signals arising from extension of the population of trailing strands resulting from extension failure. Using this information, accurate sequence readout can be obtained significantly beyond the point at which the trailing strand signals would begin to mask the correct leading strand signals. In fact, because the trailing strand signals can always be distinguished from the leading strand signals, it is possible to allow the trailing strand population to continue to grow, at the expense of the leading strands, to the point where the sequence is read from the signals generated on the trailing strand population, and the leading strand signals are treated as error signals to be corrected for. Ultimately, as the probability that a primer strand will have undergone at least one extension failure approaches unity, the signals from the leading strand population will disappear. Correspondingly the probability will increase that a trailing strand will undergo a second extension failure; the signals from this second population of double failure strands can be monitored and the single failure strand signals corrected in just the same way as the zero failure strand signals were corrected for signals due to single failure strands. Second, because knowledge of the leading strand sequence permits one to know the point to which the trailing strands have advanced, by simulating the effect of an extension failure on that known sequence in a computer, and also to know the sequence in the 1, 2 or 3 base gap between these strands and the leading strands, then for a given template sequence the dNTP probe cycle can be altered at any point to selectively extend the trailing strands while not extending the leading strands, thereby resynchronizing the populations. Alternatively the gap between leading and trailing strands can be simulated in the computer and the gap can be eliminated by reversing the dNTP cycle whenever the gap shrinks to a single base. These processes are referred to as “healing.” If a large number of different sequences are being read in parallel with the same dNTP reagents, an altered dNTP probe cycle that is correct for healing extension failure strands on a given sequence may not be correct for healing other sequences. However, with a large enough number of parallel sequence readouts, roughly one-third of the sequences will have trailing strands with a 1-base gap at any point, and so reversal of the dNTP probe cycle at arbitrary intervals will heal roughly one-third of the readouts with extension failure gaps. Repeated arbitrary reversal of the dNTP probe cycle eventually heals roughly two-thirds of all the readouts. The overall effect of these error correction and error elimination processes is to reduce, or eliminate any limitation on read length arising from extension failure. The ability to overcome the read length limitations imposed by extension failure provides significant additional flexibility in experimental design. For example, it may be that read length is not limited by extension failure, but rather by misincorporation of incorrect nucleotides, which shuts down extension on the affected strands and steadily reduces the signal, ultimately to the point where it is not detectable with the desired accuracy. In this case, the ability to eliminate the effects of extension failure allows the experimenter great flexibility to alter the reaction conditions in such a way that misincorporation is minimized, at the expense of an increased incidence of extension failure. Misincorporation frequency depends in part on the concentration of the probing dNTP's and the reaction time allowed. Longer reaction times, or higher dNTP concentrations result in an increased probability of misincorporation, but a reduced incidence of extension failure. Therefore, if a higher level of extension failure can be tolerated due to, for example, the computer-aided signal discrimination and dNTP cycle-reversal healing methods, then reaction times and/or dNTP reagent concentrations can be reduced to minimize misincorporation, with the resulting increase in extension failure being countered by the computer-aided signal discrimination and/or dNTP cycle-reversal healing techniques described above. If the deoxyribonucleotides used for the polymerase reaction are impure a small fraction of strands will extend when the main nucleotide is incorrect and produce a population of leading, rather than trailing, error strands. As with the trailing strands, the leading strand population is never more than three bases, nor less than one base, ahead of the main population, unless a second error occurs on the same strand, and also, regardless of where an incorrect extension by an impurity dNTP occurs, the leading strands are all in phase with each other. A given base site can be probed either 1, 2 or 3 times with an incorrect dNTP before it must be extended by the correct dNTP, so on the average twice. If each of the incorrect dNTP's is assumed to carry the same percentage of dNTP impurity, then the probability of incorrect extension by, e.g. 99% pure dNTP containing the correct complementary base as an impurity is 1%÷3 (only ⅓ of the impurity will be the correct complementary base)×2 (average 2 incorrect trials between each correct extension), that is, 0.67%. As with trailing strands, the leading strand population can produce out-of-phase extension signals that complicate the readout of the majority strand sequence, as shown in FIG. 15. Because the sequence downstream of the 3′ terminus of the majority strands is not known at the time of extension of those strands, the signal due to leading strand extension can not immediately be corrected for, nor can an altered dNTP cycle be calculated which would automatically heal the gap between majority and leading strands for a given template sequence. However similar methods can be used to ameliorate the effects of a leading strand population. First, as with trailing strands, reversal of the dNTP probe cycle automatically heals the gap between leading and majority strand populations whenever the gap shrinks to a single base. Therefore, arbitrary reversal of the dNTP probe cycle has a ⅓ probability of healing the gap for a given sequence, or will heal ⅓ of the sequences in a large population of sequences probed in parallel. Continued arbitrary reversal eventually heals roughly two-thirds of such gaps. Second, although the sequence downstream of the 3′ terminus of the majority strands is not immediately known, information about this sequence becomes available as soon as the majority strands traverse the gap region. Therefore, for each extension of the majority strands it is possible, ideally using a computer simulation, to calculate when the leading strand population would have traversed that base and thus the signal by which a prior extension of the majority strands would have been contaminated. In this way the majority strand extension signals can retrospectively be corrected for leading strand signals. There are important aspects to leading strand creation that reduce the frequency of occurrence of leading strand events. First, if the concentration of impurity dNTP's is sufficiently low, a leading strand population cannot be created by impurity extension of the first base of a repeat. This is because the probability of incorrect incorporation of two impurity bases on the same strand in the same reaction cycle is the square of the probability for a single incorporation, and therefore vanishingly small for small impurity levels. Therefore, whenever the correct dNTP for extension of the repeat length is supplied, all strands will be extended to completion when the correct nucleotide is supplied, regardless of whether some fraction of the strands were already partially extended by one base of the repeat. Second, not all incorrect extensions result in a permanent phase difference. For a permanent phase difference to result, a second extension (by a correct base) must occur on the leading strand before the main strands extend to catch up to the leading strand. Labeling the next four sites along the template sequence: 1, 2, 3, 4, then, by definition, if a leading strand is created by incorporation of an impurity base on site 1 while the majority of the strands do not extend, the main nucleotide supplied is incorrect for extension at site 1. If the main nucleotide supplied is correct for extension at site 2, a 2-base lead is created. There is 1 chance in 4 that the reaction chamber contains the correct nucleotide for site 2, so the probability of creating a 2-base extension in a single step (with an impurity extension followed by a correct extension) is ¼ the probability of the impurity extension alone. For the 0.67% impurity extension probability cited above, this means a 0.16% probability of creating a 2-base extension in a single cycle. However, if the main nucleotide supplied is incorrect for further extension at site 2, and, by definition incorrect for extension at site 1, then for the lead to become fixed, the correct nucleotide for site 2 must be supplied before the correct nucleotide to extend at site 1. The probability that site 2 will extend before site 1 is therefore 50%; for a 0.67% impurity extension probability, the probability that this creates a fixed lead due to a second extension by a correct nucleotide is 0.33%. Overall, a 1% impurity level results in ˜0.5% probability of creating a leading strand in any given reaction trial. Preparation of specific embodiments in accordance with the present invention will now be described in further detail. These examples are intended to be illustrative and the invention is not limited to the specific materials and methods set forth in these embodiments. EXAMPLE 1 A microcalorimetic experiment was performed which demonstrates for the first time the successful thermal detection of a DNA polymerase reaction. The results are shown in FIG. 3. Approximately 20 units of T7 Sequenase was injected into a 3 mL reaction volume containing approximately 20 nmol of DNA template and complementary primer, and an excess of dNTPs. The primer was extended by 52-base pairs, the expected length given the size of the template. Using a commercial microcalorimeter (TAM Model 2273; Thermometrics, Sweden) a reaction enthalpy of 3.5-4 kcal per mole of base was measured (FIG. 3). This measurement is well within the value required for thermal detection of DNA polymerase activity. This measurement also demonstrates the sensitivity of thermopile detection as the maximum temperature rise in the reaction cell was 1×10−3 C. The lower trace seen in FIG. 3 is from a reference cell showing the injection artifact for an enzyme-free injection into buffer containing no template system. EXAMPLE 2 To illustrate the utility of mutant T4 polymerases, two primer extension assays were performed with two different mutant T4 polymerases, both of which are exonuclease deficient. In one mutant, Asp112 is replaced with Ala and Glu114 is replaced with Ala (D112A/E114A). The exonuclease activity of this mutant on double-stranded DNA is reduced by a factor of about 300 relative to the wild type enzyme as described by Reha-Krantz and Nonay (1993, J. Biol. Chem. 268:27100-27108). In a second polymerase mutant, in addition to the D112A/E114A amino acid substitutions, a third substitution replaces Ile417 with Val (I417V/D112A/E114A). The 1417V mutation increases the accuracy of synthesis by this polymerase (Stocki, S. A. and Reha-Krantz, L. J, 1995, J Mol. Biol. 245:15-28; Reha-Krantz, L. J. and Nonay, R. L., 1994, J. Biol. Chem. 269:5635-5643) Two separate primer extension reactions were carried out using each of the polymerase mutants. In the first, only a single correct nucleotide, dGTP, corresponding to a template C was added; The next unpaired template site is a G so that misincorporation would result in formation of a G-G mispair. A G-G mispair tends to be among the most difficult mispairs for polymerases to make. In the second primer extension reaction, two nucleotides, dGTP and dCTP, complementary to the first three unpaired template sites were added. Following correct incorporation of dGMP and dCMP, the next available template site is a T. Formation of C-T mispairs tend to be very difficult while G-T mispairs tend to be the most frequent mispairs made by polymerases. Time courses for primer extension reactions by both mutant T4 polymerases are shown in FIG. 4. Low concentrations of T4 polymerase relative to primer/template (p/t) were used so that incorporation reactions could be measured on convenient time scales (60 min). By 64 minutes 98% of the primers were extended. In reactions containing only dGTP, both polymerases nearly completely extended primer ends by dGMP without any detectable incorporation of dGMP opposite G. In reactions containing both dGMP and dCMP, both polymerases nearly completely extended primer ends by addition of one dGMP and two dCMP's. A small percentage (≈1%) of misincorporation was detectable in the reaction catalyzed by the D112A/E114Amutant. Significantly, no detectable misincorporation was seen in the reaction catalyzed by the I417V/D112A/E114A mutant. EXAMPLE 3 In accordance with the invention a fluorescent tag may be attached to the nucleotide base at a site other than the 3′ position of the sugar moiety. Chemistries for such tags which do not interfere with the activity of the DNA polymerase have been developed as described by Goodwin et al. (1995, Experimental Technique of Physics 41:279-294). Generally the tag is attached to the base by a linker arm of sufficient length to move the bulky tag out of the active site of the enzyme during incorporation. As illustrated in FIG. 5, a nucleotide can be connected to a fluorophore by a photocleavable linker, e.g., a benzoin ester. After the tagged dNMP is incorporated onto the 3′ end of the DNA primer strand, the DNA template system is illuminated by light at a wave length corresponding to the absorption maximum of the fluorophore and the presence of the fluorophore is signaled by detection of fluorescence at the emission maximum of the fluorophore. Following detection of the fluorophore, the linker may be photocleaved to produce compound 2; the result is an elongated DNA molecule with a modified but non-fluorescent nucleotide attached. Many fluorophores, including for example, a dansyl group or acridine, etc., will be employed in the methodology illustrated by FIG. 5. Alternatively, the DNA template system is not illuminated to stimulate fluorescence. Instead, the photocleavage reaction is carried out to produce compound 2 releasing the fluorophore, which is removed from the template system into a separate detection chamber. There the presence of the fluorophore is detected as before, by illumination at the absorption maximum of the fluorophore and detection of emission near the emission maximum of the fluorophore. EXAMPLE 4 In a specific embodiment of the invention, a linked system consisting of a chemiluminescently tagged dNTP can consist of a chemiluminescent group (the dioxetane portion of compound 4), a chemically cleavable linker (the silyl ether), and an optional photocleavable group (the benzoin ester) as depicted in FIG. 6. The cleavage of the silyl ether by a fluoride ion produces detectable chemiluminescence as described in Schaap, et al. (1991, “Chemical and Enzymatic Triggering of 1, 2-dioxetanes: Structural Effects on Chemiluminescence Efficiency” in Bioluminescence & Chemiluminescence, Stanley, P. E. and Knicha, L. J. (Eds), Wiley, N.Y. 1991, pp. 103-106). In addition, the benzoin ester that links the nucleoside triphosphate to the silyl linker is photocleavable as set forth in Rock and Chan (1996, J. Org. Chem. 61: 1526-1529); and Felder, et al. (1997, First International Electronic Conference on Synthetic Organic Chemistry, Sept. 1-30). Having both a chemiluminescent tag and a photocleavable linker is not always necessary; the silyl ether can be attached directly to the nucleotide base and the chemiluminescent tag is destroyed as it is read. As illustrated in FIG. 6 with respect to compound 3, treatment with fluoride ion liberates the phenolate ion of the adamantyl dioxetane, which is known to chemiluminesce with high efficiency (Bronstein et al., 1991, “Novel Chemiluminescent Adamantyl 1, 2-dioxetane Enzyme Substrates,” in Bioluminescence & Chemiluminescence, Stanley, P. E. and Kricka, R. J. (eds), Wiley, N.Y. 1991 pp. 73-82). The other product of the reaction is compound 4, which is no longer chemiluminescent. Compound 4 upon photolysis at 308-366 nm liberates compound 2. The synthesis of compound 1 is achieved by attachment of the fluorophore to the carboxyl group of the benzoin, whose α-keto hydroxyl group is protected by 9(FMOC), followed by removal of the FMOC protecting group and coupling to the nucleotide bearing an activated carbonic acid derivative at its 3′ end. Compound 4 is prepared via coupling of the vinyl ether form of the adamantyl phenol, to chloro(3-cyanopropyl)dimethylsilane, reduction of the cyano group to the amine, generation of the oxetane, and coupling of this chemiluminescence precursor to the nucleotide bearing an activated carbonic acid derivative at its 3′ end. The chemiluminescent tag can also be attached to the dNTP by a cleavable linkage and cleaved prior to detection of chemiluminescence. As shown in FIG. 7, the benzoin ester linkage in compound 3 may be cleaved photolytically to produce the free chemiluminescent compound 5. Reaction of compound 5 with fluoride ion to generate chemiluminescence may then be carried out after compound 5 has been flushed away from the DNA template primer in the reaction chamber. As an alternative to photolytic cleavage, the tag may be attached by a chemically cleavable linker which is cleaved by chemical processing which does not trigger the chemiluminescent reaction. EXAMPLE 5 In this example, the nucleotide sequence of a template molecule comprising a portion of DNA of unknown sequence is determined. The DNA of unknown sequence is cloned into a single stranded vector such as M13. A primer that is complementary to a single stranded region of the vector immediately upstream of the foreign DNA is annealed to the vector and used to prime synthesis in reactive sequencing. For the annealing reaction, equal molar ratios of primer and template (calculated based on the approximation that one base contributes 330 g/molto the molecular weight of a DNA polymer) is mixed in a buffer consisting of 67 mM TrisHCl pH 8.8, 16.7 mM (NH4)2SO4, and 0.5 mM EDTA. This buffer is suitable both for annealing DNA and subsequent polymerase extension reactions. Annealing is accomplished by heating the DNA sample in buffer to 80° C. and allowing it to slowly cool to room temperature. Samples are briefly spun in a microcentrifuge to remove condensation from the lid and walls of the tube. To the DNA is added 0.2 mol equivalents of T4 polymerase mutant I417V/D112A/E114A and buffer components so that the final reaction cell contains 67 mM TrisHCl pH 8.8, 16.7 mM (NH4)2SO4, 6.7 mM MgCl2 and 0.5 mM dithiothreitol. The polymerase is then queried with one dNTP at a time at a final concentration of 10 ÿM. The nucleotide is incubated with polymerase at 37° C. for 10s. Incorporation of dNTPs may be detected by one of the methods described above including measuring fluorescence, chemiluminescence or temperature change. The reaction cycle will be repeated with each of the four dNTPs until the complete sequence of the DNA molecule has been determined. EXAMPLE 6 FIG. 7 illustrates a mechanical fluorescent sequencing method in accordance with the invention. A DNA template and primer are captured onto beads 18 using, for example, avidin-biotin or —NH2/n-hydroxysuccinimide chemistry and loaded behind a porous frit or filter 20 at the tip of a micropipette 22 or other aspiration device as shown in FIG. 7(a), step 1. Exonuclease deficient polymerase enzyme is added and the pipette tip is lowered into a small reservoir 24 containing a solution of fluorescently-labeled dNTP. As illustrated in step 2 of FIG. 7(a), a small quantity of dNTP solution is aspirated through the filter and allowed to react with the immobilized DNA. The dNTP solution also contains approximately 100 nM polymerase enzyme, sufficient to replenish rinsing losses. After reaction, as shown in step 3, the excess dNTP solution 24 is forced back out through the frit 20 into the dNTP reservoir 24. In step 4 of the process the pipette is moved to a reservoir containing buffer solution and several aliquots of buffer solution are aspirated through the frit to rinse excess unbound dNTP from the beads. The buffer inside the pipette is then forced out and discarded to waste 26. The pipette is moved to a second buffer reservoir (buffer 2), containing the chemicals required to cleave the fluorescent tag from the incorporated dNMP. The reaction is allowed to occur to cleave the tag. As shown in step 5 the bead/buffer slurry with the detached fluorescent tag in solution is irradiated by a laser or light source 28 at a wavelength chosen to excite the fluorescent tag, the fluorescence is detected by fluorescence detector 30 and quantified if incorporation has occurred. Subsequent steps depend on the enzyme strategy used. If a single-stage strategy with an exonuclease-deficient polymerase is used, as illustrated in FIG. 7(b), the solution containing the detached fluorescent tag is discarded to waste (step 6) which is expelled, followed by a further rinse step with buffer 1 (step 7) which is thereafter discarded (step 8) and the pipette is moved to a second reservoir containing a different dNTP (step 9) and the process repeats starting from step 3, cycling through all four dNTPs. In a two-stage strategy, after the correct dNTP has been identified and the repeat length quantified in step 5, the reaction mixture is rinsed as shown in steps 6, 7, and 8 of FIG. 7(b) and the pipette is returned to a different reservoir containing the same dNTP (e.g., dNTPI) as shown in step (a) of FIG. 8 to which a quantity of exonuclease-proficient polymerase has been added and the solution is aspirated for a further stage of reaction which proofreads the prior extension and correctly completes the extension. This second batch of dNTP need not be fluorescently tagged, as the identity of the dNTP is known and no sequence information will be gained in this proof-reading step. If a tagged dNTP is used, the fluorescent tag is preferably cleaved and discarded as in step 5 of FIG. 7(a) using Buffer 2. Alternatively, the initial incorporation reaction shown in step 2 of FIG. 7(a) is carried out for long enough, and the initial polymerase is accurate enough, so that the additional amount of fluorescent tag incorporated with dNTP1 at step a of FIG. 8 is small and does not interfere with quantification of the subsequent dNTP. Following proof-reading in step a of FIG. 8, excess dNTP is expelled (step b) and the reaction mixture is rinsed (steps c, d) with a high-salt buffer to dissociate the exo+polymerase from the DNA primer/template. It is important not to have exonuclease-proficient enzyme present if the DNA primer/template is exposed to an incorrect dNTP. The pipette is then moved to step e, in which the reservoir contains a different dNTP, and the process is repeated, again cycling through all four dNTPs. EXAMPLE 7 A new process for destruction of a fluorophore signal which involves reaction of the electronically excited fluorophore with an electron-abstracting species, such as diphenyliodonium salts, is described. The reaction of a diphenyliodonium ion with an electronically excited fluorescein molecule is illustrated in FIG. 10. The diphenyliodonium ion extracts an electron from the excited state of the fluorescein molecule producing a radical ion of the fluorescein molecule and a neutral diphenyliodonium free radical. The diphenyliodonium free radical rapidly decomposes to iodobenzene and a phenyl radical. The fluorescein radical ion then either reacts with the phenyl radical or undergoes an internal arrangement to produce a final product which is no longer fluorescent. FIGS. 11 and 12 demonstrate evidence for the specific destruction of fluorescein by diphenylionium ion. In FIG. 11, fluorescence spectra are presented for a mixture of fluorescein and tetramethylrhodamine dyes, before and after addition of a solution of diphenyliodonium chloride. It is seen that the fluorescence from the fluorescein dye is immediately quenched, demonstrating electron abstraction from the excited state of the molecule while the fluorescence from the rhodamine is unaffected, apart from a small decrease due to the dilution of the dye solution by the added diphenyliodonium chloride solution. Elimination of the fluorescent signal from the fluorescein dye by diphenyliodonium chloride is not in itself proof that the fluorescein molecule has been destroyed, because electron abstraction from the excited state of fluorescein effectively quenches the fluorescence, and quenching need not result in destruction of the fluorescein molecule. However, FIG. 12 demonstrates that the fluorescein molecule is destroyed by reaction with the diphenyliodonium and not simply quenched. FIG. 12 demonstrates the ultraviolet (UV) absorption spectra for a fluorescein solution before and after addition of a solution of diphenyliodonium chloride. Spectrum 1 is the UV absorption spectrum of a pure fluorescein solution. Spectrum 2 is the UV absorption of the fluorescein solution following the addition of a solution containing a molar excess of diphenyliodonium (DPI) chloride and exposure to a single flash from a xenon camera strobe. The data show that fluorescein is essentially destroyed by the photochemical reaction with the DPI ion. FIG. 12 provides clear evidence that diphenyliodonium chloride not only quenches the fluorescence from the fluorescein dye but destroys the molecule to such an extent that it can no longer act as a fluorophore. An experiment was performed to demonstrate efficient fluorescent detection and destruction of fluorophore using a template sequence. The template, synthesized with a alkyl amino linker at the 5′ terminus, was: 3′-H2N-(CH2)7-GAC CAT TAT AGG TCT TGT TAG GGA AAG GAA GA-5′ The trial sequence to be determined is: G GGA AAG GAA GA. A tetramethyrhodamine-labeled primer sequence was synthesized to be complementary to the template as follows: 5′-[Rhodamine]-(CH2)6-CTG GTA ATA TCC AGA ACA AT-3′ The alkyl amino-terminated template molecules were chemically linked to Sepharose beads derivatized with N-hydroxysuccinimide and the rhodamine-labeled primer was annealed to the template. The beads with attached DNA template and annealed primer were loaded behind a B-100 disposable filter in a 5-ml syringe. A volume containing a mixture of fluorescein-labeled and unlabelled dCTP in a ratio of 1:2 and exonuclease-deficient polymerase enzyme in a reaction buffer as specified by the manufacturer was drawn into the syringe. Reaction was allowed to proceed for 20 minutes, at 35° C. After the reaction, the fluid was forced out of the syringe, retaining the beads with the reacted DNA behind the filter, and three washes with double-distilled water were performed by drawing water through the filter into the syringe and expelling it. The beads were resuspended in phosphate buffer, the filter was removed and the suspension was dispensed into a cuvette for fluorescence analysis. Following fluorescence analysis, the bead suspension was loaded back into the syringe which was then fitted with a filter tip, and the phosphate buffer was dispensed. A solution of DPI was drawn up into the syringe with a concentration calculated to be in 1:1 molar equivalence to the theoretical amount of DNA template, the filter was removed and the bead suspension was dispensed into a cuvette for UV light exposure for 15 minutes. The suspension was recollected into a syringe, the filter was reattached, the DPI solution was expelled, and the beads were resuspended by drawing up 0.7 mL of phosphate buffer. After removal of the filter the bead suspension was dispensed into a clean cuvette for fluorescence analysis to check the completeness of destruction of the fluorescein by the reaction with the DPI. A subsequent polymerase reaction was performed using the same protocol with labeled dTTP and similarly measured for fluorescence. FIG. 13 demonstrates the results of the polymerase reactions, with photochemical destruction of the fluorescein label by DPI following each nucleotide incorporation reaction. Curve 1 shows rhodamine fluorescence following annealing of the rhodamine labeled primer to the beads, demonstrating covalent attachment of the template strands to the beads and capture of the rhodamine-labeled primer strands. Curve 2 demonstrates detection of fluorescein following polymerase-catalyzed incorporation of three partially fluorescein-labeled dCMPs onto the 3′ terminus of the primer strands. Curve 3 shows complete destruction of the incorporated fluorescein label by photo-induced reaction with diphenyliodonium chloride. Loss of rhodamine signal here is attributed to loss of a significant fraction of the beads which stuck to the filter during washes. Curve 4 shows detection of a new fluorescein label following photochemical destruction of the fluorescein attached to the dCMP's and subsequent polymerase-catalyzed incorporation of three partially fluorescein-labeled dTMPs onto the 3′ terminus of the primer strands. The following methods were utilized to demonstrate successful destruction of a fluorescein-labeled dTMP. Sepharose beads were purchased from Amersham with surfaces derivatized with N-hydroxysuccinimide for reaction with primary amine groups. The alkyl amino-terminated templates were chemically linked to the Sepharose beads using the standard procedure recommended by the manufacturer. The beads with attached template were suspended in 250 mM Tris buffer containing 250 mM NaCl and 40 nM MgCl 2. The solution containing the primer strands was added and the mixture heated to 80° C. and cooled over 2 hours to anneal the primers to the surface-immobilized DNA template strands. Fluorescein-labeled dUTP and dCTP were purchased from NEN Life Science Products. Unlabeled dTTP and dCTP were purchased from Amersham. Prior to any reaction, the annealed primer/template was subjected to fluorescence analysis to ensure that annealing had occurred. The excitation wavelength used was 320 nm and fluorescence from fluorescein and rhodamine was detected at ˜520 nm and ˜580 nm respectively. Reagent volumes were calculated on the assumption that the DNA template was attached to the beads with 100% efficiency. The 5X reaction buffer contained: 1) 250 mM Tris buffer, pH 7.5 2) 250 mM NaCl 3) 40 mM MgCl2 4) 1 mg/mL BSA 5) 25 mM dithiothreitol (DTT) mixed and brought to volume with double-distilled H2O T4 DNA polymerase was obtained from Worthington Bio-chemical Corp. The polymerase was dissolved in the polymerase buffer according to the manufacturer's protocols. Fluorescein-labeled and unlabeled dCTP's were mixed in a ratio of 1:2. The reaction was run in a 5 mL syringe (Becton Dickinson) fitted with a B-100 disposable filter (Upchurch Scientific). This limits the reaction volume to 5 mL total: Primer template suspension 0.7 mL T4 DNA Polymerase 1.0 mL FdCTP/dCTP 0.040 mL 5X reaction buffer 2.0 mL double-dist. H2O 1.0 mL The reaction was allowed to proceed in a 35° C. oven for 20 minutes. Following reaction, the fluid was forced out of the syringe allowing the filter to retain the beads with the reacted DNA. Three washes with double-distilled water were performed. All waste was collected and saved for future reuse. The beads were resuspended in 0.7 mL of phosphate buffer, the filter was removed and the suspension was dispensed into a cuvette for fluorescence analysis. Following fluorescence analysis the bead suspension was collected into a 1 mL syringe (Becton Dickinson) which was then fitted with a filter tip. The phosphate buffer was dispensed and the waste collected. A solution of diphenyliodonium chloride (DPI) was drawn up with a concentration calculated to be in 1:1 molar equivalence to the theoretical amount of DNA template (i.e. DPI was present in excess of the incorporated fluorescein-labeled dCTP). The filter was removed and the bead suspension with added DPI was dispensed into a cuvette and exposed to UV light for 15 minutes. The suspension was recollected into a syringe, the filter reattached, the DPI solution was dispensed and the beads were resuspended in 0.7 mL of phosphate buffer. The bead suspension was dispensed into a clean cuvette for fluorescence analysis. It should be noted that a significant fraction of the beads used in this procedure appeared to become stuck in the filter on the syringe. This resulted in a significant increase in the pressure needed to force fluids through the filter as it became clogged by the beads, and more importantly reduced the amount of DNA available for fluorescent detection of incorporated nucleotides and reduced the weak rhodamine signal from the labeled primer to the point where it was no longer detectable. Following the successful incorporation reaction with dCTP, a subsequent polymerase reaction was run to incorporate dTTP. The incorporated fluorescein-labeled dTMP was detected, but with significantly lower intensity due to the losses of the beads in the filter in the multiple transfer steps between the reaction syringe and the analysis cuvette. The lowered signal could also result in part from a different labeling efficiency of the dTTP and a different incorporation efficiency for the labeled nucleotide in the polymerase reaction. Because the rhodamine signal was no longer detectable following the second incorporation reaction it was not possible to correct for bead losses. The results are shown in FIG. 13. The data represented by the curves were obtained sequentially as follows: Curve 1 shows the rhodamine fluorescence following annealing of the rhodamine-labeled primer to the bead-immobilized DNA template. Curve 2 demonstrates detection of the fluorescein-labeled dCTP following polymerase-catalyzed incorporation of three dCMP's onto the 3′ terminus of the primer strands. Curve 3 demonstrates complete destruction of the incorporated fluorescein label on the dCMP's by photo-induced reaction with dipenyliodonium chloride. In this instance, the rhodamine label also has vanished; this is primarily because a significant fraction of the beads were lost by sticking in the filter used in the reagent flushing operation. It is possible that the rhodamine also was destroyed by the DPI photochemical reaction. Curve 4 demonstrates detection of a new fluorescein label following photochemical destruction of the fluorescein label on the dCMP's and polymerase-catalyzed incorporation of three fluorescein-tagged dTMP's onto the 3′ terminus of the primer strands. The lower signal compared to curve 2 results mainly from the bead losses in the syringe, but may also reflect a lower incorporation efficiency of the dTMP and/or a lower labeling efficiency. Because the rhodamine signal from the labeled primer is no longer detectable, the bead losses cannot be calibrated. The results shown here demonstrate the concept of reactive sequencing by fluorescent detection of DNA extension followed by photochemical destruction of the fluorophore, which allows further extension and detection of a subsequent added fluorophore. This cycle can be repeated a large number of times if sample losses are avoided. In practical applications of this approach, such losses will be avoided by attaching the primer or template strands to the fixed surface of an array device, for example a microscope slide, and transferring the entire array device between a reaction vessel and the fluorescent reader. EXAMPLE 8 Read length is defined as the maximum length of DNA sequence that can be read before uncertainties in the identities of the DNA bases exceed some defined level. In the reactive sequencing approach, read length is limited by two types of polymerase failures: misincorporation, i.e., incorrectly incorporating a noncomplementary base, and extension failure, i.e.,failure to extend some fraction of the DNA primer strands on a given cycle in the presence of the correct complementary base. Example 2 demonstrated that reaction conditions can be optimized such that neither type of failure affects more than ˜1% of the arrayed strands for any given incorporation reaction. Neither type of failure directly produces an error signal in the sequence readout, because neither a 1% positive signal, for a misincorporation, nor a 1% decrease in the signal for a correct incorporation, in the case of extension failure, will be significant compared to the signals anticipated for a correct incorporation. However, accumulated failures limit the read length in a variety of different ways. For example, misincorporation inhibits any further extension on the affected strand resulting in a reduction in subsequent signals. It is estimated that the probability of continuing to extend a given strand following a misincorporation is no greater than 0.1%, so that any contribution to the fluorescent signal resulting from misincorporation followed by subsequent extension of the error strand will be negligible. Instead, the accumulation of misincorporations resulting in inhibition of strand extension ultimately reduces the overall signal amplitude for correct base incorporation to a level at which noise signals in the detection system begin to have a significant probability of producing a false signal that is read as a true base incorporation. Extension failures typically arise due to the kinetics of the extension reaction and limitations on the amount of time allotted for each extension trial with the single deoxynucleotide triphosphates (dNTP's). When reaction is terminated by flushing away the dNTP supply, a small fraction of the primer strands may remain unextended. These strands on subsequent dNTP reaction cycles will continue to extend but will be out of phase with the majority strands, giving rise to small out-of-phase signals, i.e., signaling a positive incorporation for an added dNTP which is incorrect for extension of the majority strands. Because extension failure can occur, statistically, on any extension event, the out-of-phase signals will increase as the population of strands with extension failures grows. If reaction conditions are chosen so that the reaction is 99.9% complete on a given reaction cycle, for example, after a further number, N, of successful extension reactions, the out-of-phase signal will be approximately (1-0.999N). The number N at which the out-of-phase signal becomes large enough to be incorrectly read as a correct extension signal is the read length. For example, after extension by 200 bases with 99.9% completion, the out-of-phase signal is approximately 18% of the in-phase signal, for a single base extension in either case. After extension by 400 bases the out-of-phase signal grows to 33%. The point at which the read must terminate is dictated by the ability to distinguish the in-phase signals from the out-of-phase signals. In what follows, a length of single base repeats, e.g. AAAAA, is treated as a single base for the purposes of discussing the phase difference between strands. If the reaction cycle of the four dNTP's is unchanged, then a primer strand which has failed to extend when the correct dNTP, for example dATP, is in the reaction cell cannot trail the leading, i.e., majority strands, which did extend correctly, by more than 3 bases because the fourth base in the dNTP reaction cycle will always once again be the correct base (dATP) for the strand which failed to extend previously. It is assumed that extension failure is purely statistical, and that any strand which fails to extend has an equal chance of subsequent extension when the correct dNTP is supplied, and that this extension probability is sufficiently high that the chance of repeated extension failures on the same strand is vanishingly small. For example, if the probability of extension failure on a single strand is 0.1%, the probability of two extension failures on the same strand is (0.001)2 or 10−6. Similarly, the trailing strand can never resynchronize with the leading strands if extension subsequently proceeds correctly, because the leading strands will always have extended by at least one more nucleotide —G, T, or C in the example discussion of an A extension failure—before the trailing strand can add the missing A. The effect is that after each complete dNTP cycle the trailing strands always follow the leading strands by an extension amount that represents the bases added in one complete dNTP cycle at a given point in the sequence. These observations predict that: (i) the gap between the leading and trailing strands perpetually oscillates between 1 and 3 bases and can never increase unless a second extension failure occurs on the same strand; and (ii) the gap between the leading and trailing strands is independent of the position along the trailing strand at which the extension failure occurs. This gap at any given point in the extension of the leading strands is solely a function of the sequence of the leading strand population up to that point and the dNTP probe cycle. In other words, a population of trailing strands is produced due to random extension failure at different points in the sequence, but these trailing strands themselves are all exactly in phase with each other. Because the result of an extension failure is to produce a trailing strand population that trails the leading strands perpetually by an amount that oscillates between one and three nucleotides, assuming that a second extension failure does not occur on the trailing strand and that the probing dNTP cycle remains unchanged, therefore the gap between the leading and trailing strand populations can always be known by tracking the leading strand sequence by, for example, computer simulation and simulating an extension failure event at any point along the sequence. Thus the present invention provides, first, a general method of computer tracking of the sequence information which allows the out-of-phase error signals due to extension of trailing strands to be recognized and subtracted from the correct signals, and, second, methods of altering the probing dNTP cycle to selectively extend the trailing strands so that they move back into phase with the leading strands, thus completely eliminating sequence uncertainty due to out-of-phase signals arising from the trailing strands that result from extension failure. The statistics which govern the ability to distinguish an incorrect signal from out-of-phase strands from a correct signal depend upon the noise level and statistical variation of the fluorescence signal. Assuming that the signal for a correct 1-base extension has a standard deviation of ±5%, then statistically 99.75% of the signals will have an amplitude between 0.85 and 1.15 (±3 standard deviations from the average value) when the average value is 1.0 and the standard deviation is 0.05. If the extension signal must be at least 85% of the average single extension signal to register a correct extension, then statistically a correct extension will be missed only 0.13% of the time, i.e. the readout accuracy would be 99.87%. Another 0.13% of the signals for a correct extension will be greater than 1.15, but the concern is only with signals that are lower than average and so are more difficult to distinguish from a growing signal from out-of-phase strands. The statistics for errors arising from out-of-phase extension of a trailing strand are similar. If the standard deviation of the trailing strand signals is also ±5% of the mean extension signal which will be true whenever the trailing strand intensity approaches the leading strand intensity, then if the trailing strand intensity does not grow beyond 0.7, the fraction of trailing strand extensions that give rise to a signal of 0.85 or greater 4 standard deviations beyond the mean is less than 0.01%. Thus an out-of phase signal arising from a single-base extension on one of the three sets of trailing strands should be distinguishable from the in-phase signal with accuracy so long as the out-of-phase signal does not grow beyond −70% of the in-phase signal. The above discussion assumes that all the extension events correspond to single base extensions. However, multiple single-base repeats are common in DNA sequences, thus one must consider the situation where the out-of-phase signal can be M times larger than that for a single base extension, where M is the repeat number. For example, if the population of one of the three sets of out-of-phase strands has grown to 20% of the leading strand population, at which level the in-phase and out-of-phase signals can readily be distinguished for a single base extension, then if this set of out-of-phase strands encounters a 5-base repeat, e.g. AAAAA, the signal for that repeat becomes identical in magnitude to that for a single base extension on the in-phase strands. Real-time computer monitoring of the extension signals permits discrimination against such repeat-enhanced out-of-phase signals, for example, by implementing linear and/or non-linear auto-regressive moving average (ARMA) schemes. The essential points here are as follows (i) the out-of-phase strands are those that are trailing the majority strands as a result of extension failure; misincorporation events which could produce leading error strands have the effect of shutting down further extension on the affected strands and so do not give rise to significant out-of-phase error signals; (ii) there is always only one population of trailing strands regardless of where the extension failure occurred; all the primer strands in this population have been extended to the same point which trails the leading strand sequence by 1, 2 or 3 bases; and (iii) because the leading strands have always previously traversed the sequence subsequently encountered by the trailing strands, the sequence at least 1 base beyond the 3′ terminus of the trailing strands is always known and allows prediction of exactly whether, and by how much, these trailing strands will extend for any nucleotide supplied, by simulating, in a computer for example, the effect of an extension failure at any point in the known sequence upstream of the position to which the leading strands have advanced. On each incorporation trial, in addition to any possible correct extension signal for the leading strands, there may also be an error signal corresponding to extension of the trailing strands. For example, let us assume that the trailing strand population has grown as large as 20% of the leading strand population. The size of this population can be monitored by detecting the incorporation signal when the trailing strands extend and the leading strands do not. Assume that the leading strand population has just traversed a single base repeat region on the template, for example AAAAA, and incorporated onto the primer the complementary T repeat: TTTTT. The trailing strands will not traverse this same AAAAA repeat for at least a complete cycle of the four probing nucleotides, until the next time the strands are probed with dTTP. Knowing the size of the trailing strand population from the amplitude of its incorporation signals, determined at any point where the leading strands do not extend but the trailing strands do, the signal to be expected from the trailing strand population due to the TTTTT incorporation can be calculated precisely. If the trailing strand population is ⅕ as large as the leading strand population, for example, this signal will mimic incorporation of a single T on the leading strand population. In the absence of the computer-aided monitoring method discussed here, such a false signal would give rise to a drastic sequence error. FIGS. 14A and 14B demonstrate how data would appear for a sequence: [CTGA] GAA ACC AGA AAG TCC [T], probed with a dNTP cycle: CAGT, close to the primer where no extension failure has occurred (FIG. 14A) and well downstream (FIG. 14B) at a point where 60% of the strands have undergone extension failure and are producing out-of-phase signals, and misincorporation has shut down extension on 75% of all strands. The readouts shown start at the second G in the sequence (beyond the [CTGA] sequence in parentheses) and end at the last C (before the [T] in parentheses). The digital nature of the signal in FIG. 14A and also the amplitude scale should be noted. In FIG. 14B, the signal for a single base extension has been reduced by 60%, from 1.0 to 0.4 due to the extension failure strands, and by a further factor of 4 to 0.1 due to misincorporation and the resulting 75% signal loss. However, added to the correct extension signals are signals due to the out-of-phase extension of the trailing strands. At first sight, the readout is completely different from the correct readout shown in FIG. 14A, due to the superposition of signals produced when the trailing strands encounter the sequence previously traversed by the leading strands. Particularly large errors arise whenever the trailing strand population encounters the AAA repeats. For example, the second T probe yields a signal amplitude corresponding to an AAAAA repeat instead of the correct single A, the third G probe gives a signal corresponding to CCC when in fact there is no C at this point in the leading strand sequence, the fourth T probe reads 4 A's when the correct sequence has none (the trailing strands encounter the second AAA repeat). However, because the sequence from the leading strands is known, the false signals arising from the trailing strands can be predicted and subtracted from the total signal to obtain the correct sequence readout. This is shown in FIG. 14C, where the signals arising from the trailing strands are coded by different shading from the leading strand signal. Because the signals due to the trailing strands can be predicted, the error signals can be subtracted to obtain the correct digital sequence readout shown in FIG. 14D. It should be noted that the data in FIG. 14D are now identical to those in FIG. 14A, and yield the correct sequence readout for the leading strands, the only difference being that the overall intensity is reduced due to the assumed loss of signal due to misincorporation and extension failure, the latter populating the trailing strands. In other words, by keeping track of the sequence in a computer the effect is as though one could directly visualize the different contributions as depicted on the plot in FIG. 14C. Therefore, it is possible to predict for any probe nucleotide event exactly what the signal from the trailing strand population should be, and subtract this error signal from the measured signal to arrive at a true digital signal representative of the sequence of the leading strand population, which is the desired result. Given the ability to compute and subtract any trailing strand signals as discussed, the accuracy with which nucleotide incorporation or non-incorporation on the leading strands can be sensed is limited, not by the absolute size of the trailing strand signal, but instead by the noise on those signals. For example, assume that the signal for a single-base extension of a trailing strand population equal to 20% of the leading strand population is 0.2±0.05. If the trailing strands encounter a 5-base repeat, the resulting signal would be identical in amplitude to that produced by a single-base extension of the leading strands, but this signal could be subtracted from the observed signal to yield either a signal resulting from a leading strand extension, or a null signal corresponding to no extension of the leading strands. Assuming that the noise is purely statistical and therefore is reduced in proportion to the square root of the signal amplitude, for a 5-base extension of the trailing strands or a single extension of the leading strands the signal would be 1±(0.05×{square root}5), i.e. 1±0.11, because the statistical noise on a set of added signals grows as the square root of the number of signals. One can subtract from this value a correction signal which is much more accurately known because the trailing strand signal has been repeatedly measured yielding better statistics on this value. It is assumed that the uncertainty in the correction signal is negligible. For no extension of the leading strands, the resulting difference signal would be 0±0.11, whereas a single extension of the leading strands would yield a difference signal of 1±0.11; the two signals are distinguishable with better than 99.9% accuracy. The example given here is an extreme case: in fact, the extension failure can be corrected at any point, so that it will be possible to minimize the trailing strand population below a level where it would produce signals that make the leading strand sequence uncertain. There are additional advantages to the computer-aided monitoring method proposed. First, the signals from the trailing strands serve as an additional check on the leading strand sequence. Second, the trailing strand population could be allowed to surpass the leading strand population in magnitude. Without computer-aided monitoring, readout would have to cease well before this point, however, with computer-aided monitoring, readout can continue, now using the trailing strands rather than the leading strands to reveal the sequence. Thus, the strand population that trails due to only one extension failure now becomes the leading strand population for the purposes of computer aided monitoring. This allows readout to continue until further complications arise from the occurrence of 2 extension failures on the same strand, producing a new trailing strand population which can be tracked in the same way as the single failure strands, while the population of strands that have undergone no error failure diminishes to the point where it contributes no detectable signal. Optimization of reagents, enzyme and reaction conditions should allow misincorporation probabilities below 1%, and extension failure probabilities as low as 0.1%. The computer aided monitoring method of the present invention additionally provides a means for healing the trailing strand population by selectively extending this population so that it is again synchronous with the leading strands. For example, given a dNTP probe cycle of GCTA, and a template sequence (beyond the 3′ end of the primer) of: ......GTGCAGATCTG ... and assuming that when dCTP is in the reaction chamber, the polymerase fails to incorporate a C in some fraction of the primer strands, the following results: Template ......GTG CAG ATC TG ... Main strands ......C Template ......GTG CAG ATC TG Failure strands ...... At the end of the first cycle, the main strands have extended by . . . CA, while the failure strand has not advanced. After one more complete cycle, the main strand extension is . . . CAC and the failure strand now reads . . . CA, i.e. now just one base out of phase. Template ......GTG CAG ATC TG ... Main strands ......CAC Template ......GTG CAG ATC TG Failure strands ......CA Because the phase lag arises from the repeating interaction of the probe cycle sequence with the template sequence, the unchanged probe cycle can never have the correct sequence to resynchronize the strands. Instead, if the probe cycle is unchanged, and if no further extension failures occur, the phase lag for a given failure strand oscillates perpetually between 1 and 3 bases, counting single base repeats as one base for this purpose. However because the leading strand sequence up to the last extension is always known, one can determine the effect of introducing an extension failure at some upstream position. It should be noted that an extension failure introduced at any arbitrary upstream position, or any base type, always produces the same phase lag because the effect of an extension failure is to cause extension of the affected strand to lag by one complete dNTP cycle. Thus, it is possible to alter the probe cycle sequence, for example to probe with a C, instead of a G, after the last A in the sequence discussed above. The failure strand would advance while the main strands did not and the phase lag would heal. In yet another embodiment the dNTP probe cycle may be reversed whenever the phase lag shrinks to only 1 base. Whenever the phase difference declines to a single base, or repeats of a single base, then simply reversing the probe cycle sequence always resynchronizes the strands. FIG. 15 shows how a leading strand population arising from incorrect extension of a fraction of primer strands due to nucleotide impurities can adversely affect the signals from the main population. Using the same template sequence as before: [CTGA] GAA ACC AGA AA GTC C [TC AGT] and the same probe cycle: CAGT, the effect of a leading strand population which is 20% of the main strand population can be simulated and 2 bases ahead of the main strands at the time the main strand sequence begins to be read. The leading strands have already extended by -C TTT. The first C probe extends the main primer strands by one base complementary to the first G in the sequence giving a single base extension signal of 1. The first G extends the leading strands by -GG- complementary to the -CC- repeat, giving a signal of 0.4. Greater ambiguity arises when the leading strands encounter the second AAA-repeat at the second T probe, increasing the main strand signal from the correct value for a single base extension to 1.6. In the absence of further information, this value will be ambiguous or may be interpreted as a 2-base repeat. Correction for these ambiguities comes from the fact that the correct sequence of the main strands is read following the leading strand read. In general, a large multiple repeat which can give an error signal when encountered by the leading strands will subsequently give a larger signal when encountered by the main strands, and superimposed on this correct signal will be a leading strand signal for which there are three possibilities: (i) zero signal: the leading strands do not extend; (ii) small signal that does not create ambiguity—the leading strands extend by a single base or a repeat number small enough not to simulate an additional base extension of the main strands; (iii) large signal; the leading strands encounter a second large repeat. By monitoring the main strand sequence, it is possible at each extension to retroactively estimate the effects of a leading strand population and subtract such signals from the main strand signals to arrive at a correct sequence. In the case where the leading strands encounter a repeat large enough to create ambiguity in the sequence, even if the leading strands subsequently encounter a second or third large repeat when the main strands encounter the first repeat, the main strands will eventually traverse the same region to give sufficient information to derive the correct sequence. In other words, the sequence information at any point is always overde-termined—the signal for any given extension is always read twice, by the leading strands and the main strands, and so yields sufficient information to determine both the correct sequence and the fractional population of the leading strands, which are the two pieces of information required. Because the sequence of the leading strand population produced by impure nucleotides cannot be known until it is subsequently traversed by the main strands, one cannot know what dNTP probe cycle would act to extend the main strands while not extending the leading strands, as was the case for a trailing strand population produced by extension failure. However, as with trailing strands, the gap between the leading and main strands oscillates perpetually between one and three bases, and can be reconnected by reversing the dNTP probe sequence whenever the gap between the leading and main strands shrinks to a single base. Although it cannot be known when this single base gap occurs, the dNTP probe sequence can be reversed at regular intervals. Trials indicate that such a process ultimately reconnects approximately ⅔ of the leading strands. The statistics for this process are as follows. Statistically, because the gap between the main and leading strands can be 1, 2 or 3 bases, there is a ⅓ probability that the leading strand population will have only a 1-base phase lag at any time the cycle is reversed. The 1-base phase difference will always be healed by a cycle reversal. Another ⅓ of the time the leading strands are 2 bases ahead at the time the cycle is reversed. For the next probing base the following possibilities exist: Lead Main strand strand 0 0 No extension on either strand: Prob. 3/4 × 3/4 = 9/16 +1 0 Phase lag increases: Prob. 1/4 × 3/4 = 3/12 +1 +1 Both strands advance: Prob. 1/4 × 1/4 = 1/16 0 +1 Phase lag decreases: Prob. 3/4 × 1/4 = 3/12 Phase lag stays at 2: Number of chances = 10/16 Phase lag decreases Number of chances = 3/12 Phase lag increases Number of chances = 3/12 So the chance of making a 2-base gap worse is ({fraction (3/12)})/({fraction (10/16)}+{fraction (3/12)})=28%. Considering all three gap sizes: 1-base gap heals (33% of population); 2-base gap gets worse 28% of the time: only ⅓ of gaps are 2 base, so 9% total get worse; 3-base gap also gets worse 28% of the time, again 9% overall effect. In sum, 33% heal at a given reversal, 18% lose at a given reversal and the remaining 50% are unchanged. Even assuming the 18% are permanently lost (and a 2 base gap increased to a 3 base gap can still rejoin), at each subsequent reversal ⅓ of the 50% of strands are healed, which are unchanged by the previous reversal, as follows: Reversal # Fraction of gaps healed 1 33% 2 17% 3 9% 4 4.5% 5 2.5% 6 1% Total ˜67% Therefore, repeated reversal of the dNTP probe cycle can reduce by ⅔ the effects of out-of-phase signals due to incorrect extension by nucleotide impurities, or random extension failure, effectively increasing the read length when limited by either effect by a factor of 3. Although the invention has been described herein with reference to specific embodiments, many modifications and variations therein will readily occur to those skilled in the art. Accordingly, all such variations and modifications are included within the intended scope of the invention.

<SOH> BACKGROUND OF INVENTION <EOH>Currently, two approaches are utilized for DNA sequence determination: the dideoxy chain termination method of Sanger (1977, Proc. Natl. Acad. Sci 74:5463-5674) and the chemical degradation method of Maxam (1977, Proc. Natl. Acad. Sci 74:560-564). The Sanger dideoxy chain termination method is the most widely used method and is the method upon which automated DNA sequencing machines rely. In the chain termination method, DNA polymerase enzyme is added to four separate reaction systems to make multiple copies of a template DNA strand in which the growth process has been arrested at each occurrence of an A, in one set of reactions, and a G, C, or T, respectively, in the other sets of reactions, by incorporating in each reaction system one nucleotide type lacking the 3′-OH on the deoxyribose at which chain extension occurs. This procedure produces a series of DNA fragments of different lengths, and it is the length of the extended DNA fragment that signals the position along the template strand at which each of four bases occur. To determine the nucleotide sequence, the DNA fragments are separated by high resolution gel electrophoresis and the order of the four bases is read from the gel. A major research goal is to derive the DNA sequence of the entire human genome. To meet this goal the need has developed for new genomic sequencing technology that can dispense with the difficulties of gel electrophoresis, lower the costs of performing sequencing reactions, including reagent costs, increase the speed and accuracy of sequencing, and increase the length of sequence that can be read in a single step. Potential improvements in sequencing speed may be provided by a commercialized capillary gel electrophoresis technique such as that described in Marshall and Pennisis (1998, Science 280:994-995). However, a major problem common to all gel electrophoresis approaches is the occurrence of DNA sequence compressions, usually arising from secondary structures in the DNA fragment, which result in anomalous migration of certain DNA fragments through the gel. As genomic information accumulates and the relationships between gene mutations and specific diseases are identified, there will be a growing need for diagnostic methods for identification of mutations. In contrast to the large scale methods needed for sequencing large segments of the human genome, what is needed for diagnostic methods are repetitive, low-cost, highly accurate techniques for resequencing of certain small isolated regions of the genome. In such instances, methods of sequencing based on gel electrophoresis readout become far too slow and expensive. When considering novel DNA sequencing techniques, the possibility of reading the sequence directly, much as the cell does, rather than indirectly as in the Sanger dideoxynucleotide approach, is a preferred goal. This was the goal of early unsuccessful attempts to determine the shapes of the individual nucleotide bases with scanning probe microscopes. Additionally, another approach for reading a nucleotide sequence directly is to treat the DNA with an exonuclease coupled with a detection scheme for identifying each nucleotide sequentially released as described in Goodwin, et al., (1995, Experimental Techniques of Physics 41:279-294). However, researchers using this technology are confronted with the enormous problem of detecting and identifying single nucleotide molecules as they are digested from a single DNA strand. Simultaneous exonuclease digestion of multiple DNA strands to yield larger signals is not feasible because the enzymes rapidly get out of phase, so that nucleotides from different positions on the different strands are released together, and the sequences become unreadable. It would be highly beneficial if some means of external regulation of the exonuclease could be found so that multiple enzyme molecules could be compelled to operate in phase. However, external regulation of an enzyme that remains docked to its polymeric substrate is exceptionally difficult, if not impossible, because after each digestion the next substrate segment is immediately present at the active site. Thus, any controlling signal must be present at the active site at the start of each reaction. A variety of methods may be used to detect the poly-merase-catalyzed incorporation of deoxynucleoside monophosphates (dNMPs) into a primer at each template site. For example, the pyrophosphate released whenever DNA polymerase adds one of the four dNTPs onto a primer 3′ end may be detected using a chemiluminescent based detection of the pyrophosphate as described in Hyman E. D. (1988, Analytical Biochemistry 174:423-436) and U.S. Pat. No. 4,971,903. This approach has been utilized most recently in a sequencing approach referred to as “sequencing by incorporation” as described in Ronaghi (1996, Analytical Biochem. 242:84) and Ronaghi (1998, Science 281:363-365). However, there exist two key problems associated with this approach, destruction of unincorporated nucleotides and detection of pyrophosphate. The solution to the first problem is to destroy the added, unincorporated nucleotides using a dNTP-digesting enzyme such as apyrase. The solution to the second is the detection of the pyrophosphate using ATP sulfurylase to reconvert the pyrophosphate to ATP which can be detected by a luciferase chemiluminescent reaction as described in U.S. Pat. No. 4,971,903 and Ronaghi (1998, Science 281:363-365). Deoxyadenosine α-thiotriphosphate is used instead of dATP to minimize direct interaction of injected dATP with the luciferase. Unfortunately, the requirement for multiple enzyme reactions to be completed in each cycle imposes restrictions on the speed of this approach while the read length is limited by the impossibility of completely destroying un-incorporated, non-complementary, nucleotides. If some residual amount of one nucleotide remains in the reaction system at the time when a fresh aliquot of a different nucleotide is added for the next extension reaction, there exists a possibility that some fraction of the primer strands will be extended by two or more nucleotides, the added nucleotide type and the residual impurity type, if these match the template sequence, and so this fraction of the primer strands will then be out of phase with the remainder. This out of phase component produces an erroneous incorporation signal which grows larger with each cycle and ultimately makes the sequence unreadable. A different direct sequencing approach uses dNTPs tagged at the 3′ OH position with four different colored fluorescent tags, one for each of the four nucleotides is described in Metzger, M. L., et al. (1994, Nucleic Acids Research 22:4259-4267). In this approach, the primer/template duplex is contacted with all four dNTPs simultaneously. Incorporation of a 3′ tagged NMP blocks further chain extension. The excess and unreacted dNTPs are flushed away and the incorporated nucleotide is identified by the color of the incorporated fluorescent tag. The fluorescent tag must then be removed in order for a subsequent incorporation reaction to occur. Similar to the pyrophosphate detection method, incomplete removal of a blocking fluorescent tag leaves some primer strands unextended on the next reaction cycle, and if these are subsequently unblocked in a later cycle, once again an out-of-phase signal is produced which grows larger with each cycle and ultimately limits the read length. To date, this method has so far been demonstrated to work for only a single base extension. Thus, this method is slow and is likely to be restricted to very short read lengths due to the fact that 99% efficiency in removal of the tag is required to read beyond 50 base pairs. Incomplete removal of the label results in out of phase extended DNA strands.

<SOH> SUMMARY OF INVENTION <EOH>Accordingly, it is an object of the present invention to provide a novel method for determining the nucleotide sequence of a DNA fragment which eliminates the need for electrophoretic separation of DNA fragments. The inventive method, referred to herein as “reactive sequencing”, is based on detection of DNA polymerase catalyzed incorporation of each of the four nucleotide types, when deoxynucleoside triphosphates (dNTP's) are supplied individually and serially to a DNA primer/template system. The DNA primer/template system comprises a single stranded DNA fragment of unknown sequence, an oligonucleotide primer that forms a matched duplex with a short region of the single stranded DNA, and a DNA polymerase enzyme. The enzyme may either be already present in the template system, or may be supplied together with the dNTP solution. Typically a single deoxynucleoside triphosphate (dNTP) is added to the DNA primer template system and allowed to react. As used herein deoxyribonucleotide means and includes, in addition to dGTP, dCTP, dATP, dTTP, chemically modified versions of these deoxyribonucleotides or analogs thereof. Such chemically modified deoxyribonucleotides include but are not limited to those deoxyribonucleotides tagged with a fluorescent or chemiluminescent moiety. Analogs of deoxyribonucleotides that may be used include but are not limited to 7-deazapurine. The present invention additionally provides a method for improving the purity of deoxynucleotides used in the polymerase reaction. An extension reaction will occur only when the incoming dNTP base is complementary to the next unpaired base of the DNA template beyond the 3′ end of the primer. While the reaction is occurring, or after a delay of sufficient duration to allow a reaction to occur, the system is tested to determine whether an additional nucleotide derived from the added dNTP has been incorporated into the DNA primer/template system. A correlation between the dNTP added to the reaction cell and detection of an incorporation signal identifies the nucleotide incorporated into the primer/template. The amplitude of the incorporation signal identifies the number of nucleotides incorporated, and thereby quantifies single base repeat lengths where these occur. By repeating this process with each of the four nucleotides individually, the sequence of the template can be directly read in the 5′ to 3′ direction one nucleotide at a time. Detection of the polymerase mediated extension reaction and quantification of the extent of reaction can occur by a variety of different techniques, including but not limited to, microcalorimetic detection of the heat generated by the incorporation of a nucleotide into the extending duplex. Optical detection of an extension reaction by fluorescence or chemiluminescence may also be used to detect incorporation of nucleotides tagged with fluorescent or chemiluminescent entities into the extending duplex. Where the incorporated nucleotide is tagged with a fluorophore, excess unincorporated nucleotide is removed, and the template system is illuminated to stimulate fluorescence from the incorporated nucleotide. The fluorescent tag may then be cleaved and removed from the DNA template system before a subsequent incorporation cycle begins. A similar process is followed for chemiluminescent tags, with the chemiluminescent reaction being stimulated by introducing an appropriate reagent into the system, again after excess unreacted tagged dNTP has been removed; however, chemiluminescent tags are typically destroyed in the process of readout and so a separate cleavage and removal step following detection may not be required. For either type of tag, fluorescent or chemiluminescent, the tag may also be cleaved after incorporation and transported to a separate detection chamber for fluorescent or chemiluminescent detection. In this way, fluorescent quenching by adjacent fluorophore tags incorporated in a single base repeat sequence may be avoided. In addition, this may protect the DNA template system from possible radiation damage in the case of fluorescent detection or from possible chemical damage in the case of chemiluminescent detection. Alternatively the fluorescent tag may be selectively destroyed by a chemical or photochemical reaction. This process eliminates the need to cleave the tag after each readout, or to detach and transport the tag from the reaction chamber to a separate detection chamber for fluorescent detection. The present invention provides a method for selective destruction of a fluorescent tag by a photochemical reaction with diphenyliodonium ions or related species. The present invention further provides a reactive sequencing method that utilizes a two cycle system. An exonuclease-deficient polymerase is used in the first cycle and a mixture of exonuclease-deficient and exonuclease-proficient enzymes are used in the second cycle. In the first cycle, the template-primer system together with an exonuclease-deficient polymerase will be presented sequentially with each of the four possible nucleotides. In the second cycle, after identification of the correct nucleotide, a mixture of exonuclease proficient and deficient polymerases, or a polymerase containing both types of activity will be added in a second cycle together with the correct dNTP identified in the first cycle to complete and proofread the primer extension. In this way, an exonuclease-proficient polymerase is only present in the reaction cell when the correct dNTP is present, so that exonucleolytic degradation of correctly extended strands does not occur, while degradation and correct re-extension of previously incorrectly extended strands does occur, thus achieving extremely accurate strand extension. The present invention also provides a method for monitoring reactive sequencing reactions to detect and correct sequencing reaction errors resulting from misincorporation, i.e., incorrectly incorporating a non-complementary base, and extension failure, i.e., failure to extend a fraction of the DNA primer strands. The method is based on the ability to (i) determine the size of the trailing strand population (trailing strands are those primer strands which have undergone an extension failure at any extension prior to the current reaction step); (ii) determine the downstream sequence of the trailing strand population between the 3′ terminus of the trailing strands and the 3′ terminus of the corresponding leading strands (“downstream” refers to the template sequence beyond the current 3′ terminus of a primer strand; correspondingly, “upstream” refers to the known template and complementary primer sequence towards the 5′ end of the primer strand; “leading strands” are those primer strands which have not previously undergone extension failure); and (iii) predict at each extension step the signal to be expected from the extension of the trailing strands through simulation of the occurrence of an extension failure at any point upstream from the 3′ terminus of the leading strand. Subtraction of the predicted signal from the measured signal yields a signal due only to valid extension of the leading strand population. In a preferred embodiment of the invention, the monitoring for reactive sequencing reaction errors is computer-aided. The ability to monitor extension failures permits determination of the point to which the trailing strands for a given template sequence have advanced and the sequence in the 1, 2 or 3 base gap between these strands and the leading strands. Knowing this information the dNTP probe cycle can be altered to selectively extend the trailing strands for a given template sequence while not extending the leading strands, thereby resynchronizing the populations. The present invention further provides an apparatus for DNA sequencing comprising: (a) at least one chamber including a DNA primer/template system which produces a detectable signal when a DNA polymerase enzyme incorporates a deoxyribonucleotide monophosphate onto the 3′ end of the primer strand; (b) means for introducing into, and evacuating from, the reaction chamber at least one selected from the group consisting of buffers, electrolytes, DNA template, DNA primer, deoxyribonucleotides, and polymerase enzymes; (c) means for amplifying said signal; and (d) means for converting said signal into an electrical signal.

20040505

20100112

20050210

90773.0

RILEY, JEZIA

METHOD OF DETERMINING THE NUCLEOTIDE SEQUENCE OF OLIGONUCLEOTIDES AND DNA MOLECULES

UNDISCOUNTED

CONT-ACCEPTED

ACCEPTED

METHOD AND SYSTEM FOR DETECTING FIRE IN A PREDETERMINED AREA

A method and system for detecting early fires in a predetermined area includes capturing a plurality of images of the predetermined area during an interval for generating a plurality of difference frames, and detecting a number of pixels that have fire characteristics in each difference frame. If the detection result indicates that the flame of the predetermined area substantially increases during the interval, the method outputs an early fire alarm that can provide more time for firefighting. Thus, both early fire detection and reduction of false fire alarms are achieved.

1. A method for detecting early fires in a predetermined area, the method comprising: (a) capturing a plurality of images of the predetermined area during an interval for generating a plurality of difference frames; (b) detecting a number of pixels that have fire characteristics in each difference frame; and (c) if the result of step (b) indicates that a flame in the predetermined area substantially increases during the interval, outputting an early fire alarm. 2. The method of claim 1 wherein step (b) includes: determining if each pixel of each difference frame complies with the following rules: R>Rt; R≧G>B; and S≧((255−R)*St/Rt); wherein R is a value of a red component of the pixel, Rt is a threshold of the red component, G is a value of a green component of the pixel, B is a value of a blue component of the pixel, S is saturation of the pixel, St is a threshold of saturation; and if a pixel complies with the above rules, adjusting the number of pixels that have fire characteristics of the difference frame. 3. The method of claim 2 wherein when the value of the red component of a pixel is Rt, the saturation of the pixel is St. 4. The method of claim 1 wherein in step (c), if the result of step (b) indicates that a ratio of spreading flame in the predetermined area is over a threshold of spreading flame during the interval, then outputting the early fire alarm. 5. The method of claim 1 wherein step (a) including: comparing two images captured for generating a difference of the two images; and removing noise from the difference for generating a difference frame. 6. A method for detecting a number of pixels that have fire characteristics in a difference frame, the method comprising: determining if each pixel of the difference frame complies with the following rules: R>Rt; R≧G>B; and S≧((255−R)*St/Rt); wherein R is a value of a red component of the pixel, Rt is a threshold of the red component, G is a value of a green component of the pixel, B is a value of a blue component of the pixel, S is saturation of the pixel, St is a threshold of saturation; and if a pixel complies with the above rules, adjusting the number of pixels that have fire characteristics of the difference frame. 7. The method of claim 6 wherein when the value of the red component of a pixel is Rt, the saturation of the pixel is St. 8. The method of claim 6 wherein a video detecting system captures images in a predetermined area and the difference frame is generated by removing noise of a difference of two images captured by the video detecting system. 9. A video detecting system comprising: an image capturing device for capturing images; a logic unit for performing the following steps: (a) controlling the image capturing device to capture a plurality of images of a predetermined area during an interval for generating a plurality of difference frames; (b) detecting a number of pixels that have fire characteristics in each difference frame; and (c) if the result of step (b) indicates that a flame in the predetermined area substantially increases during the interval, outputting an early fire alarm. 10. The video detecting system of claim 9 wherein step (b) performed by the logic unit includes: determining if each pixel of the difference frame complies with the following rules: R>Rt; R≧G>B; and S≧((255−R)*St/Rt); wherein R is a value of a red component of the pixel, Rt is a threshold of the red component, G is a value of a green component of the pixel, B is a value of a blue component of the pixel, S is saturation of the pixel, St is a threshold of saturation; and if a pixel complies with the above rules, adjusting the number of pixels that have fire characteristics of the difference frame. 11. The video detecting system of claim 10 wherein when the value of the red component of a pixel is Rt, the saturation of the pixel is St. 12. The video detecting system of claim 9 wherein if the result of step (b) indicates that a ratio of spreading flame in the predetermined area is over a threshold of spreading flame during the interval, the logic unit outputs the early fire alarm. 13. The video detecting system of claim 9 wherein step (a) performed by the logic unit includes: comparing two images captured for generating a difference of the two images; and removing noise from the difference for generating a difference frame. 14. The video detecting system of claim 9 wherein the logic unit is a logic circuit. 15. The video detecting system of claim 9 wherein the logic unit is a program code. 16. A video detecting system comprising: an image capturing device for capturing images; a logic unit for performing the following steps: (a) determining if pixels of difference frames complies with the following rules, the difference frames generated from images captured by the video detecting system: R>Rt; R≧G>B; and S≧((255−R)*St/Rt); wherein R is a value of a red component of the pixel, Rt is a threshold of the red component, G is a value of a green component of the pixel, B is a value of a blue component of the pixel, S is saturation of the pixel, St is a threshold of saturation; and (b) if a pixel complies with the above rules, adjusting a number of pixels that have fire characteristics of the difference frame. 17. The video detecting system of claim 16 wherein when the value of the red component of a pixel is Rt, the saturation of the pixel is St. 18. The video detecting system of claim 16 wherein step (a) performed by the logic unit includes: comparing two images captured for generating a difference of the two images; and removing noise from the difference for generating a difference frame. 19. The video detecting system of claim 16 wherein the logic unit is a logic circuit. 20. The video detecting system of claim 16 wherein the logic unit is a program code.

BACKGROUND OF INVENTION 1. Field of the Invention The present invention relates to a method and system for detecting early fires in a predetermined area, and more particularly, to a method and system that can detect if images contain flames and if a flame increases to be a fire. 2. Description of the Prior Art Generally, a HSI (hue/saturation/intensity) domain is usually utilized for analyzing images, since hue, saturation and intensity can represent all combinations of light to describe color. One prior art method detects if images have flames in the HSI domain. The method includes capturing images in a predetermined area, transforming RGB of each pixel of the images into HSI, and determining if the HSI of each pixel complies with rules in the HSI domain. In the prior art, the RGB of each pixel is transformed into the HSI by the following equations: I = 1 3 ⁢ ( R + G + B ) , 0 ≤ I ≤ 1 ( 1 ) S = ⁢ 1 - 3 ( R + G + B ) ⁡ [ min ⁡ ( R , G , B ) ] , 0 ≤ S ≤ 1 H = ⁢ { θ if ⁢ ⁢ B ≤ G 360 - θ if ⁢ ⁢ B > G , θ = ⁢ cos - 1 ⁢ { 1 2 ⁡ [ ( R - G ) + ( R + B ) ] [ ( R - G ) 2 + ( R - B ) ⁢ ( G - B ) ] 1 2 } ( 2 ) 0 ⁢ ° ≤ H ≤ 360 ⁢ ° ( 3 ) In the prior art, HSI is utilized for analyzing flame. The HSI domain is divided into six regions, as shown in FIG. 1. Fig. 1 is a table of hue, RGB model and color range. The color range of a common fire is from red to yellow; therefore, the hue of fire is from 0 to 60 degrees. Saturation of a fire changes with background illumination. For instance, the color of a fire during the day or under an extra light source has a stronger saturation than that of during the night or having no light source. That is, the color of a fire during the day or with the extra light source displays less white while the color of fire during the night or having no light source displays more white. A fire found in images captured during the night is more white in hue because the fire is the typically the only luminous entity in the images. Additionally, for providing sufficient brightness in video processing, the intensity should be over a threshold. Experimental results according to the prior art show that each HSI pixel of a fire should satisfy the following conditions: 0°≦H≦60° Brighter environment: 30≦S≦100, Darker environment: 20≦S≦100, 127≦I≦255 The method mentioned above for detecting fire includes a series of complicated equations to transform RGB into HSI, which requires intensive computations. Besides, the low bound of the saturation condition (ii) may be too small to work correctly and hence it will yield a false fire-detection due to the appearance of reflected flames. Furthermore, in a fire detecting system, another important function is to generate a fire alarm to prevent a fire accident. The method for generating a fire alarm according to the prior art compares the number of fire pixels to a threshold. If the number of fire pixels in an image is larger than the threshold, a fire alarm is output. However, the method is confined by the distance between the fire and an image capturing device (such as a camera). This enormously increases the false fire alarm rate and thus cannot adequately achieve the purpose of detecting early fires. For example, suppose that the size of a flame is constant, such as a flame of a candle or a lighter. This kind of flame does not constitute a fire accident; therefore, a fire alarm is not required. Please refer to FIG. 2 to FIG. 5. FIG. 2 and FIG. 4 are diagrams of the same flame 20 of a lighter and an image capturing device 12 separated by different distances. FIG. 2 shows that the flame 20 is far away from the image capturing device 12 and FIG. 4 shows that the flame 20 is near the image capturing device 12. The image capturing device 12 only captures images in a predetermined area. If the distance of the flame 20 and the image capturing device 12 is longer, as d1 shows in FIG. 2, the size of the flame 20 in a frame is much smaller; that is, the number of fire pixels is small, as shown in FIG. 3. On the contrary, if the distance of the flame 20 and the image capturing device 12 is shorter, as d2 shows in FIG. 4, the size of the flame 20 in a frame is much larger; that is, the number of fire pixels is large as shown in FIG. 4. As shown in FIG. 3 and FIG. 5, the flame 20 in FIG. 3 approximately occupies 1.4 squares and the flame 20 in FIG. 5 approximately occupies 14 squares. Suppose that the threshold is 7 squares, the fire alarm is not provided due to the result of FIG. 3 while the fire alarm is provided due to the result of FIG. 5. The same flame 20 of the lighter results in different effects due to the distance of the flame 20 to the image capturing device 12. The result of FIG. 3 does not lead to a false fire alarm, but the result of FIG. 5 does. In another situation, supposing that the flame spreads out and forms a fire, a fire alarm should be generated. Please refer to FIG. 6 to FIG. 17. FIGS. 6, 8, and 10 show a flame 30 spreading out to be flames 40 and 50, the distance from the image capturing device 12 being d1. FIGS. 7, 9, and 11 show numbers of fire pixels of FIGS. 6, 8, and 10, respectively. FIGS. 12, 14, and 16 show a flame 30 spreading out to be flames 40 and 50, the distance from the image capturing device 12 being the shorter d2. FIGS. 13, 15, and 17 show numbers of fire pixels of FIGS. 12, 14, and 16, respectively. The image capturing device 12 only captures images in a predetermined area. If the distance between the flames 30, 40, and 50 and the image capturing device 12 is d1, the sizes of the flame 30, 40, and 50 in a frame are much smaller; that is, the numbers of fire pixels are small, as shown in FIGS. 7, 9, and 11. On the contrary, if the distance between the flames 30, 40, and 50 and the image capturing device 12 is d2, the sizes of the flame 30, 40, and 50 in a frame are much larger; that is, the numbers of fire pixels are large, as shown in FIGS. 13, 15, and 17. Suppose that the fire alarm is given if the number of fire pixels reaches 15. Although the flame 30 has spread to be the flame 50 thereby causing a fire accident, the fire alarm is not generated due to the result of FIG. 11 so occupants are not alerted to escape from the fire accident. Because the distance between the image capturing device 12 and the scene of the fire is longer, the image capturing device 12 has no ability to detect that the fire exists. Although the fire alarm is correctly provided due to the result of FIG. 17, this is only because the distance between the image capturing device 12 and the flame 50 is just right. In the prior art, the position of the fire cannot be detected in a real environment. The image capturing device 12 cannot accurately detect if a fire is formed. Therefore, the fire alarm cannot be efficiently provided to prevent a fire accident. SUMMARY OF INVENTION It is therefore a primary objective of the claimed invention to provide a method for detecting early fires in a predetermined area to solve the above-mentioned problem. The claimed invention includes capturing a plurality of images in a predetermined area for generating a plurality of difference frames during an interval, detecting a number of pixels that have fire characteristics in each difference frame, and if the detection result indicates that the flame of the predetermined area substantially increases during the interval, outputting an early fire alarm. These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a table of hue, RGB model, and color range. FIG. 2 to FIG. 17 show the detection of early fires and the numbers of fire pixels according to the prior art. FIG. 18 is a graph of red component R versus saturation S. FIG. 19 is a diagram of a video detecting system. FIG. 20 is a flowchart of detecting early fires according to the present invention. FIG. 21 to FIG. 44 show the detection of early fires and the numbers of fire pixels according to the present invention. DETAILED DESCRIPTION In order to shed light on the present invention, the first discussion relates how to detect fire pixels of frames, and the second discussion relates how to detect a flame increasing to become a fire. Finally, the best embodiment of detecting early fires, which combines the first method with the second method, is disclosed. To provide less-computational fire-detecting rules and overcome the problem of small low-bound in condition (ii) described previously, we develop a more cost-effective and reliable fire-detection strategy. Two basic ideas behind the proposed technique are based on direct processing with RGB model and solving the problem of the reflected flames. As mentioned above, the color range of a common fire is from red to yellow. From the table in FIG. 1, the relation of R, G, and B is R≧G>B. If the RGB value of a pixel complies with the rule, the pixel may be a fire pixel. Then, other detections are required to be performed for the pixel. Because fire is a light source, the image capturing device needs sufficient brightness to capture useful image sequences. From the color of fire, R is the maximum of R, G, and B and is thus the major component. There should be a stronger R in a fire image. Hence, the value of the R component should be over a threshold, Rt, which is obtained from the results of experiments. However, background illumination can affect the saturation of flames or generate a false appearance of flame so that false fire detection occurs. To prevent such a mistake caused by the background illumination, the saturation of flames must satisfy a determined equation to eliminate the false appearance of flame. The determined equation is also obtained from the result of experiments. Based on the explanation above, the rules are described as follows: rule 1: R>Rt rule 2: R≧G>B rule 3: IF (S≧(S≧((255−R)*St/Rt)) fire pixel ELSE not fire pixel S is simplified by rule 2, S = 1 - 3 ⁢ B ( R + G + B ) , 0≦S≦1 In rule 3, when the value of the red component of a pixel is Rt, the saturation of the pixel is St. St and Rt are obtained from a great number of experiment values. Both St and Rt are affected by the background illumination, such as that during the day or the night. Therefore, St and Rt change with the environment. In rule 3, when R increases up to the value 255, the result should be zero. That is, S of fire pixels increases with R increasing while the result of rule 3 decreases. Please refer to FIG. 18. FIG. 18 is a graph of R versus S, obtained from many experiments. The background illumination during the day is brighter; thus, R is smaller and S is larger. Conversely, the background illumination during the night is darker; thus, R is larger and S is smaller. The range of Rt is from 100 to 150 and the range of corresponding S is from 70 to 50, both obtained from experiments. These two ranges are suitable for detecting flames in both conditions, the day and the night. Detecting flames by the three rules only requires calculating S according to RGB instead of transforming RGB into HSI. Also, the present invention reduces a lot of calculation by directly utilizing RGB for detecting if pixels captured are fire pixels. In addition, the color range of flames is from red to yellow and R is the maximum of components R, G, and B of a fire pixel, as shown in FIG. 1. Therefore, the basis of a flame is the R component. Thus, the present invention utilizes R as the basis for detecting flames. For instance, R must be over a threshold, Rt, and satisfy the relation R≧G>B. Finally, in order to reduce the effect of the background illumination, S must be over a result of an equation, rule 3. In the prior art, intensity I is an average of R, G, and B, as shown in equation (1), and G and B are considered in intensity I. Therefore, the prior art cannot accurately detect fire characteristics. Hence, the three rules of the present invention are more accurate than the prior art. The next discussion relates how to detect if a flame is increasing to be a fire. After detecting flames by the three rules, the number of fire pixels of each image can be calculated. Repeats of capturing images and recording the number of fire pixels of each image are required for the detection. Capturing K images and determining if the number of fire pixels increases over P %*K times indicates whether a flame is spreading out to become a fire, and if a fire alarm should be generated. For instance, suppose that K is 100 and P is 70. After capturing 100 images and calculating the numbers of fire pixels of each image, the number of fire pixels is compared between sequential images. If the number of fire pixels in a latter image is larger than that in a former image, the number of fire pixels has increased. In other words, the number of fire pixels of the i-th image is compared to that of the i+1-th image, and the number of fire pixels of the i+1-th image is compared to that of the i+2-th image, and so on. If the number of fire pixels increases over 70 (K*P %=100*70%=70) times, the flame is detected as spreading out to become a fire and a fire alarm should be generated. The methods mentioned above are carried out in a fire detection system. Please refer to FIG. 19. FIG. 19 is a diagram of the video detecting system 10 of the present invention. The image capturing device 12 is utilized for capturing images. A logic unit 14 controls the image capturing device 12 to capture a plurality of images 16 in a predetermined area during an interval for generating a plurality of difference frames, detects a number of fire pixels in each difference frame, and outputs a fire alarm if the detection result indicates that the flame of the predetermined area substantially increases during the interval. FIG. 20 is a flowchart of detecting early fires according to the present invention. The steps are as follows: Step 100: start the fire detection system. Step 102: the image capturing device 12 captures a plurality of images and a background image. Step 104: detect if there is a difference between the background image and the current image; that is, perform a difference frame process. The differences between the images captured by the image capturing device 12 and the background image are retained and noise of the differences is removed for generating a plurality of difference frames. The difference between the current image and the background image is detected by the difference frame process. Step 106: detect if each pixel is a fire pixel by the three rules and record the numbers in each difference frame. If at least one of pixels is a fire pixel, go to step 108. Otherwise, if no pixel has fire characteristics, re-detect the difference between the background image and the images captured by the image capturing device 12 and go to step 104. Step 108: detect if the flame increases to be a fire according to the numbers of fire pixels of difference frames. If yes, go to step 110. If no, stay in step 108. Because pixels of difference frames are detected to be fire pixels, the flame is still small at this time. Therefore, continuously detect if the flame increases to be a fire. Step 100: if the number of fire pixels increases over K*P % times, it indicates that the flame spreads out to be a fire and a fire alarm should be generated. The present invention can reduce the calculations required and efficiently reduce the false fire alarm rate while preventing fire accidents. As mentioned above, the prior art is confined by the distance of the flame and the image capturing device so that the false fire alarm rate increases. The present invention can efficiently reduce the false fire alarm rate. For instance, suppose that the size of flame is constant, such as a flame of a candle or a lighter. This kind of flame will not bring about a fire accident; therefore, a fire alarm is not provided. Please refer to FIG. 21 to FIG. 32. FIGS. 21, 23, and 25 show the same flame 120, 130, and 140 moving due to wind, the distance between the image capturing device 12 and the flame being d1. FIGS. 22, 24, and 26 show the numbers of fire pixels of FIGS. 21, 23, and 25, respectively. FIGS. 27, 29, and 31 show the same flame 120, 130, and 140 moving due to wind, with the separation being d2. FIGS. 28, 30, and 32 show the numbers of fire pixels of FIGS. 27, 29, and 31, respectively. The image capturing device 12 captures images in the predetermined area. If the distance is d1, the sizes of the flames 120, 130, and 140 in the frames are small. Due to the flames 120, 130, and 140 being the same, the numbers of fire pixels of the flames 120, 130, and 140 are also approximately the same. The number of fire pixels does not significantly increase when continuously capturing images. Even though the wind causes the flame to move, the number just changes within a narrow range. In this case, when the present invention detects if the flame increases, the answer is no and a fire alarm is not generated. Similarly, if the distance is d2, the sizes of the flames 120, 130, and 140 in the frames are larger. However, due to the flames 120, 130, and 140 being the same, the numbers of fire pixels of the flames 120, 130, and 140 are also the substantially the same. The number of fire pixels does not significantly increase when continuously capturing images. Even though the wind causes the flame to move, the number just changes within a narrow range. Also, when the present invention detects if the flame increases, the result is negative and a fire alarm is not generated. In another situation, supposing that the flame spreads out and forms a fire, the fire alarm should be generated. Please refer to FIG. 33 to FIG. 44. FIGS. 33, 35, and 37 show a flame 150 spreading out to becomes flames 160 and 170, the distance from the image capturing device 12 being the longer d1. FIGS. 34, 36, and 38 show numbers of fire pixels of FIGS. 33, 35, and 37, respectively. FIGS. 39, 41, and 43 show the same flame 150 spreading out to become flames 160 and 170, the distance from the image capturing device 12 being the shorter d2. FIGS. 40, 42, and 44 show numbers of fire pixels of FIGS. 39, 41, and 43, respectively. The image capturing device 12 only captures images in a predetermined area. Although the distance is d1, the flame spreads out. When the image capturing device 12 captures images continuously, the number of fire pixels increases gradually. In this condition, when the present invention detects if the flame increases, the result is positive and a fire alarm is generated. Similarly, even though the flames 150, 160, and 170 are near the image capturing device 12, because the flame is spreading out, the number of fire pixels increases gradually. In this situation a fire alarm is also provided. From the examples mentioned above, the present invention efficiently reduces the false fire alarm rate. Generally, fires are formed by inflammable substances in a combustion-supporting atmosphere at suitable temperature. Equally important, it takes a period of time to form a fire. The present invention uses the period before a fire is fully formed to repeatedly record the number of fire pixels of difference frames for detecting if a flame increases, outputting a fire alarm when significant flame increase is determined. Thus, the flame can be extinguished before forming a full-scale fire. The present invention also can efficiently reduce the false fire alarm rate to achieve efficient fire detection. Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.

<SOH> BACKGROUND OF INVENTION <EOH>1. Field of the Invention The present invention relates to a method and system for detecting early fires in a predetermined area, and more particularly, to a method and system that can detect if images contain flames and if a flame increases to be a fire. 2. Description of the Prior Art Generally, a HSI (hue/saturation/intensity) domain is usually utilized for analyzing images, since hue, saturation and intensity can represent all combinations of light to describe color. One prior art method detects if images have flames in the HSI domain. The method includes capturing images in a predetermined area, transforming RGB of each pixel of the images into HSI, and determining if the HSI of each pixel complies with rules in the HSI domain. In the prior art, the RGB of each pixel is transformed into the HSI by the following equations: I = 1 3 ⁢ ( R + G + B ) , 0 ≤ I ≤ 1 ( 1 ) S = ⁢ 1 - 3 ( R + G + B ) ⁡ [ min ⁡ ( R , G , B ) ] , 0 ≤ S ≤ 1 H = ⁢ { θ if ⁢ ⁢ B ≤ G 360 - θ if ⁢ ⁢ B > G , θ = ⁢ cos - 1 ⁢ { 1 2 ⁡ [ ( R - G ) + ( R + B ) ] [ ( R - G ) 2 + ( R - B ) ⁢ ( G - B ) ] 1 2 } ( 2 ) 0 ⁢ ° ≤ H ≤ 360 ⁢ ° ( 3 ) In the prior art, HSI is utilized for analyzing flame. The HSI domain is divided into six regions, as shown in FIG. 1 . Fig. 1 is a table of hue, RGB model and color range. The color range of a common fire is from red to yellow; therefore, the hue of fire is from 0 to 60 degrees. Saturation of a fire changes with background illumination. For instance, the color of a fire during the day or under an extra light source has a stronger saturation than that of during the night or having no light source. That is, the color of a fire during the day or with the extra light source displays less white while the color of fire during the night or having no light source displays more white. A fire found in images captured during the night is more white in hue because the fire is the typically the only luminous entity in the images. Additionally, for providing sufficient brightness in video processing, the intensity should be over a threshold. Experimental results according to the prior art show that each HSI pixel of a fire should satisfy the following conditions: 0°≦H≦60° Brighter environment: 30≦S≦100, Darker environment: 20≦S≦100, 127≦I≦255 The method mentioned above for detecting fire includes a series of complicated equations to transform RGB into HSI, which requires intensive computations. Besides, the low bound of the saturation condition (ii) may be too small to work correctly and hence it will yield a false fire-detection due to the appearance of reflected flames. Furthermore, in a fire detecting system, another important function is to generate a fire alarm to prevent a fire accident. The method for generating a fire alarm according to the prior art compares the number of fire pixels to a threshold. If the number of fire pixels in an image is larger than the threshold, a fire alarm is output. However, the method is confined by the distance between the fire and an image capturing device (such as a camera). This enormously increases the false fire alarm rate and thus cannot adequately achieve the purpose of detecting early fires. For example, suppose that the size of a flame is constant, such as a flame of a candle or a lighter. This kind of flame does not constitute a fire accident; therefore, a fire alarm is not required. Please refer to FIG. 2 to FIG. 5 . FIG. 2 and FIG. 4 are diagrams of the same flame 20 of a lighter and an image capturing device 12 separated by different distances. FIG. 2 shows that the flame 20 is far away from the image capturing device 12 and FIG. 4 shows that the flame 20 is near the image capturing device 12 . The image capturing device 12 only captures images in a predetermined area. If the distance of the flame 20 and the image capturing device 12 is longer, as d 1 shows in FIG. 2 , the size of the flame 20 in a frame is much smaller; that is, the number of fire pixels is small, as shown in FIG. 3 . On the contrary, if the distance of the flame 20 and the image capturing device 12 is shorter, as d 2 shows in FIG. 4 , the size of the flame 20 in a frame is much larger; that is, the number of fire pixels is large as shown in FIG. 4 . As shown in FIG. 3 and FIG. 5 , the flame 20 in FIG. 3 approximately occupies 1.4 squares and the flame 20 in FIG. 5 approximately occupies 14 squares. Suppose that the threshold is 7 squares, the fire alarm is not provided due to the result of FIG. 3 while the fire alarm is provided due to the result of FIG. 5 . The same flame 20 of the lighter results in different effects due to the distance of the flame 20 to the image capturing device 12 . The result of FIG. 3 does not lead to a false fire alarm, but the result of FIG. 5 does. In another situation, supposing that the flame spreads out and forms a fire, a fire alarm should be generated. Please refer to FIG. 6 to FIG. 17 . FIGS. 6, 8 , and 10 show a flame 30 spreading out to be flames 40 and 50 , the distance from the image capturing device 12 being d 1 . FIGS. 7, 9 , and 11 show numbers of fire pixels of FIGS. 6, 8 , and 10 , respectively. FIGS. 12, 14 , and 16 show a flame 30 spreading out to be flames 40 and 50 , the distance from the image capturing device 12 being the shorter d 2 . FIGS. 13, 15 , and 17 show numbers of fire pixels of FIGS. 12, 14 , and 16 , respectively. The image capturing device 12 only captures images in a predetermined area. If the distance between the flames 30 , 40 , and 50 and the image capturing device 12 is d 1 , the sizes of the flame 30 , 40 , and 50 in a frame are much smaller; that is, the numbers of fire pixels are small, as shown in FIGS. 7, 9 , and 11 . On the contrary, if the distance between the flames 30 , 40 , and 50 and the image capturing device 12 is d 2 , the sizes of the flame 30 , 40 , and 50 in a frame are much larger; that is, the numbers of fire pixels are large, as shown in FIGS. 13, 15 , and 17 . Suppose that the fire alarm is given if the number of fire pixels reaches 15. Although the flame 30 has spread to be the flame 50 thereby causing a fire accident, the fire alarm is not generated due to the result of FIG. 11 so occupants are not alerted to escape from the fire accident. Because the distance between the image capturing device 12 and the scene of the fire is longer, the image capturing device 12 has no ability to detect that the fire exists. Although the fire alarm is correctly provided due to the result of FIG. 17 , this is only because the distance between the image capturing device 12 and the flame 50 is just right. In the prior art, the position of the fire cannot be detected in a real environment. The image capturing device 12 cannot accurately detect if a fire is formed. Therefore, the fire alarm cannot be efficiently provided to prevent a fire accident.

<SOH> SUMMARY OF INVENTION <EOH>It is therefore a primary objective of the claimed invention to provide a method for detecting early fires in a predetermined area to solve the above-mentioned problem. The claimed invention includes capturing a plurality of images in a predetermined area for generating a plurality of difference frames during an interval, detecting a number of pixels that have fire characteristics in each difference frame, and if the detection result indicates that the flame of the predetermined area substantially increases during the interval, outputting an early fire alarm. These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

20040513

20060829

20051117

82732.0

HUNNINGS, TRAVIS R

METHOD AND SYSTEM FOR DETECTING FIRE IN A PREDETERMINED AREA

SMALL

ACCEPTED

ACCEPTED

OVERHEAD AUTOMOTIVE AIRBAG DESIGN

An automotive overhead airbag assembly is provided including an airbag mounted on an inside surface of a vehicle roof at an airbag mount position. The airbag has an airbag stored condition and an airbag deployed position and expands downwards from said vehicle roof when in the airbag deployed position. The assembly includes at least one wing element having a first wing mounting edge mounted to the vehicle roof and a second wing mounting edge mounted to a lower deployed portion of said airbag. The first wing mounting edge extends in a transverse direction from the airbag mount position. The at least one wing element includes a wing stored condition and a wing deployed position. The at least one wing element restricts forward motion of the airbag when the airbag is in the deployed position. The assembly includes a trampoline surface formed by the at least one wing element when the at least one wing element is in said wing deployed position. The trampoline surface absorbs passenger forward momentum during vehicle impact.

1. An automotive overhead airbag assembly comprising: an airbag mounted on an inside surface of a vehicle roof at an airbag mount position, said airbag having an airbag stored condition and an airbag deployed position, said airbag expanding downwards from said vehicle roof when in said airbag deployed position; at least one wing element having a upper wing mounting edge mounted to said vehicle roof and a side wing mounting edge mounted to a lower deployed portion of said airbag, said upper wing mounting edge extending in a transverse direction from said airbag mount position, said at least one wing element having a wing stored condition and a wing deployed position, said at least one wing element restricting forward motion of said airbag when said airbag is in said deployed position; and a trampoline surface formed by said at least one wing element when said at least one wing element is in said wing deployed position, said trampoline surface absorbing passenger forward momentum during vehicle impact. 2. An automotive overhead airbag assembly as described in claim 1, wherein said at least one wing element comprises: a first wing element extending in a first transverse direction from said airbag mount position; and a second wing element extending in a second transverse direction from said airbag mount position. 3. An automotive overhead airbag assembly as described in claim 2, wherein said first wing element and said second wing element comprise triangular wing elements. 4. An automotive overhead airbag assembly as described in claim 1, further comprising: an airbag module storing said airbag when said airbag is in said airbag stored position, said airbag module having at least one slotted guide positioned on a transverse side, said at least one slotted guide permitting said at least one wing element to extend in said transverse direction while said airbag is in said airbag stored position. 5. An automotive auxiliary restraint assembly as described in claim 1, further comprising: a slotted chamber positioned on said vehicle roof, said slotted chamber extending in a transverse direction from said airbag module, said at least one wing element stored in said slotted chamber when said airbag is in said airbag stored position. 6. An automotive auxiliary restraint assembly as described in claim 1, wherein said side wing mounting edge is vertically mounted to said airbag. 7. An automotive auxiliary restraint assembly as described in claim 1, wherein said side wing mounting edge is stitched on an inner surface of said airbag. 8. An automotive auxiliary restraint assembly as described in claim 2, wherein said airbag comprises a vertically orientated center portion, said first wing element and said second wing element mounted to opposing edges of said vertically orientated center portion such that said trampoline is comprised of said first wing element, said second wing element, and said vertically orientated center portion. 9. An automotive auxiliary restraint assembly as described in claim 1, wherein said trampoline comprises said at least one wing element stretched to resist forward motion of said airbag. 10. An automotive auxiliary restraint assembly as described in claim 1, wherein said airbag is mounted to a roof rail. 11. An automotive overhead airbag assembly comprising: an airbag mounted on an inside surface of a vehicle roof at an airbag mount position, said airbag having an airbag stored condition and an airbag deployed position, said airbag expanding downwards from said vehicle roof when in said airbag deployed position; a first wing element having a first upper wing mounting edge mounted to said vehicle roof and a first side wing mounting edge mounted to a lower deployed portion of said airbag, said first upper wing mounting edge extending in a first transverse direction from said airbag mount position, said first wing element having a first wing stored condition and a first wing deployed position; a second wing element having a second upper wing mounting edge mounted to said vehicle roof and a second side wing mounting edge mounted to said lower deployed portion of said airbag, said second upper wing mounting edge extending in a second transverse direction from said airbag mount position, said second wing element having a second wing stored condition and a second wing deployed position; said first wing element restricting forward motion of said airbag when said airbag is in said deployed position; and a trampoline surface formed by said first wing element and said second wing element when said airbag is in said airbag deployed position, said trampoline surface restricting forward motion of said airbag, said trampoline surface absorbing passenger forward momentum during vehicle impact. 12. An automotive overhead airbag assembly as described in claim 11, wherein said first wing element and said second wing element comprise triangular wing elements. 13. An automotive overhead airbag assembly as described in claim 11, further comprising: an airbag module housing said airbag when said airbag is in said airbag stored position, said airbag module having a first slotted guide and a second slotted guide positioned on opposing transverse sides of said airbag module, said first and second slotted guides permitting said first and second wing elements to extend in opposing transverse directions from said airbag module while said airbag is in said airbag stored position. 14. An automotive auxiliary restraint assembly as described in claim 11, wherein said first wing element and said second wing element are stretched to resist forward motion of said airbag trampoline when said airbag is in said airbag deployed position. 15. An automotive auxiliary restraint assembly as described in claim 11, wherein said first side wing mounting edge and said second side wing mounting edge are vertically mounted to said airbag. 16. An automotive auxiliary restraint assembly as described in claim 11, wherein said airbag is mounted to a roof rail. 17. A method of restraining passenger forward momentum during a vehicular impact comprising: storing an airbag within an airbag module, said airbag module positioned on a vehicle roof, said airbag having an airbag stored condition and an airbag deployed position; deploying said airbag downwards into said airbag deployed position during the vehicular impact; simultaneously deploying at least one wing element having a upper wing mounting edge mounted to said vehicle roof and a side wing mounting edge mounted to a lower deployed portion of said airbag, said upper wing mounting edge extending in a transverse direction from said airbag mount position, said at least one wing element restricting forward motion of said airbag when said airbag is in said deployed position; engaging the passenger using a trampoline surface formed by said at least one wing element when said airbag is in said airbag deployed position, said trampoline surface absorbing passenger forward momentum during vehicle impact. 18. A method as described in claim 17, further comprising: storing said at least one wing element a slotted chamber positioned on said vehicle roof, said slotted chamber extending in a transverse direction from said airbag module, said at least one wing element stored in said slotted chamber when said airbag is in said airbag stored position; and routing said at least one wing element through at least one slotted guide positioned on a transverse side of said airbag module, said at least one slotted guide permitting said at least one wing element to extend in said transverse direction while said airbag is in said airbag stored position. 19. A method as described in claim 17, wherein said at least one wing element comprises a first wing element and a second wing element, further comprising: folding a vertically orientated right portion and a vertically orientated left portion of said airbag over a vertically orientated center portion; positioning said airbag within said airbag module such that said first wing element extends in a first transverse direction outwards from said airbag module through a first slotted chamber and said second wing element extends in a second transverse direction outwards from said airbag module through a second slotted chamber. 20. A method as described in claim 19, further comprising: exerting tension in said at least one wing element by deploying said airbag; and generating an extended passenger engagement surface comprising said at least one wing element and said airbag when said airbag is in said airbag deployed position.

BACKGROUND OF INVENTION The present invention relates generally to an overhead automotive airbag assembly and more particularly to an overhead airbag assembly with limited forward movement. Automotive vehicle design is governed by the constant and unending pursuit of improved occupant comfort and safety. Modern vehicles incorporate considerable design and manufacturing efforts to minimize injuries to occupants in the event of vehicle accidents. These safety features, however, must co-exist with the primary functional features as well as the comfort features of the vehicle. Their placement within the vehicle, therefore, must be a function of both operation of the safety component in combination with available placement within the existing vehicle operational structure. These physical placement constraints can serve to limit the freedom of placement of certain features within the automobile. Such is the case with airbag assemblies. Airbag assemblies have proven themselves to be highly beneficial and desirable to consumers. A wide variety of implementation schemes have been devised in order to improve the functionality of airbag protection assemblies. The assemblies, however, are often positioned within traditional mounting structures based upon their operational objectives. Frontal impact airbags, for instance, are commonly positioned immediately forward of the occupant and are designed to inflate towards the occupant upon vehicle impact. This requires installation immediately forward of the occupant in the steering wheel or dashboard. Placement of frontal impact airbags for rear-seated passengers is often impractical or overly complex. The resulting design scenario commonly finds these airbag assemblies positioned in these traditional mounting locations. These locations, especially the dashboard, can become prized real estate in automotive design. As additional technology and features are incorporated into automobiles, locations such as the dashboard are desirable for passenger accessible features. Present airbag assemblies can place considerable constraint on the incorporation of these new features. It would therefore, be highly desirable to afford an alternate mounting location for forward impact airbag assemblies that provided design flexibility to automotive designers such that that airbag assemblies did not place unreasonable constraints on design creativity. On approach to the placement of frontal impact airbag assemblies is to position the assemblies in an overhead position. This arrangement not only addresses the concern for useful real estate on the dashboard, but also can provide access to passengers seated in the rear without complex seat/airbag designs. The nature of present airbag assemblies, however, does not provide adequate restraint in directions perpendicular to inflation. An overhead airbag assembly, therefore, would provide insufficient resistance to forward motion since the passenger is moving in a direction perpendicular to inflation. The lack of forward motion resistance is further exacerbated by the relatively small airbag mounting arrangements. The mounting structures are commonly small compared to the inflated bags and therefore provide inadequate support for the resistance of perpendicular forces. It would, therefore, be highly desirable to have an overhead airbag assembly design with improved forward motion resistance. SUMMARY OF INVENTION It is, therefore, an object of the present invention to provide an automotive overhead airbag assembly with forward motion resistance. It is a further object of the present invention to provide an automotive overhead airbag assembly with improved overhead installation characteristics. In accordance with the objects of the present invention, an automotive overhead airbag assembly is provided. The automotive overhead airbag assembly includes an airbag mounted on an inside surface of a vehicle roof at an airbag mount position. The airbag has an airbag stored condition and an airbag deployed position and expands downwards from said vehicle roof when in the airbag deployed position. The assembly includes at least one wing element having a first wing mounting edge mounted to the vehicle roof and a second wing mounting edge mounted to a lower deployed portion of said airbag. The first wing mounting edge extends in a transverse direction from the airbag mount position. The at least one wing element includes a wing stored condition and a wing deployed position. The at least one wing element restricts forward motion of the airbag when the airbag is in the deployed position. The assembly includes a trampoline surface formed by the at least one wing element when the at least one wing element is in said wing deployed position. The trampoline surface absorbs passenger forward momentum during vehicle impact. Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a side-view illustration of an overhead airbag assembly in accordance with the present invention, the assembly illustrated in the airbag deployed position; FIG. 2 is a detail illustration of the overhead airbag assembly, the overhead airbag assembly illustrated in the airbag stored position; and FIG. 3 is a rear view illustration of the overhead airbag assembly illustrated in FIG. 1, the view illustrating the assembly wing elements. DETAILED DESCRIPTION Referring now to FIG. 1, which is an illustration of an automotive overhead airbag assembly 10 in accordance with the present invention. The overhead airbag assembly 10 is intended to be utilized in a wide variety of vehicles for a wide variety of specific configurations. It is intended, however, to provide overhead deployed airbag protection to an occupant 12 positioned within the interior 14 of a vehicle 16, such as within a vehicle seat 18. The present invention provides such protection in addition to increasing airbag engagement area and reducing forward motion. The present invention accomplishes these goals by including an airbag 20 mounted on an inside surface 22 of the vehicle roof 24 at an airbag mount position 26. Although a variety of airbag mount positions 26 on the vehicle roof 24 are contemplated and may be optimized for specific applications, one embodiment contemplates the placement of the airbag mount position 26 on the vehicle roof rail 28 (see FIG. 2). The airbag 20 has an airbag stored condition 30 (FIG. 2) and an airbag deployed position (FIG. 1) 32. The airbag 20 expands downward from the vehicle roof 24 to move from the airbag stored condition 30 to the airbag deployed position 32. The present invention improves the performance of the airbag 20 by including at least one wing element 34 having an upper wing mounting edge 36 mounted to the vehicle roof 24 and a side wing mounting edge 38 mounted to a lower deployed portion 40 of the airbag 20. The at least one wing element 34 has a wing stored condition 42 (FIG. 2) and a wing deployed position 44 (FIG. 1). The at least one wing element 34 is utilized to restrict forward motion of the airbag 20 when the airbag 20 is in the airbag deployed position 32. This is important since the airbag module 46 is commonly relatively small in size compared to the deployed airbag 20 and therefore does not alone supply sufficient passenger forward momentum 60 restraint. It is contemplated that the at least one wing element 34 can be formed in a variety of fashions. It may be formed as a triangular wing element as illustrated in FIG. 3. It may be further comprised of a first wing element 48 and a second wing element 50. The first wing element 48 extends in a first transverse direction 52 from the airbag mount position 26. The second wing element 50 extends in a second transverse direction 54 from the airbag mount position 26. By extending the wing elements 48,50 in generally opposing transverse directions 52,54 an extended passenger engagement surface 56 is generated. The extended passenger engagement surface 56 extends the practical airbag 20 surface area. In addition, it acts as a trampoline surface to further absorb passenger momentum. These characteristics are further improved through the introduction of a rearward mounting point 58, rearward of the airbag mount position 26, even with generally opposing transverse directions 52,54. The wing elements 48, 50 are attached to the airbag 20 preferably by way of the side wing mounting edge 38 which is vertically mounted to the airbag 20. The side wing mounting edge 38 may be attached to the airbag 20 in a variety of fashions, although stitching the side wing mounting edge 38 to the inner surface 62 of the airbag 20 is preferred. The airbag 20 can be divided into three vertical sections, a right vertical section 64, a center vertical section 66, and a left vertical section 68. The wing elements 48, 50 are preferably mounted to opposing edges 70 of the center vertical section 66. This optimizes the fore/aft restraint generated by the wing elements 48,50. The right vertical section 64 and left vertical section 68 can be folded over the center vertical section for installation into the airbag module 46. Although the wing elements 48,50 can be mounted to the vehicle roof 24 all along the upper wing mounting edge 36, it is contemplated that they may be physically attached in a plurality of mounting locations 71 to simplify assembly while providing sufficient support. The airbag 20, when in the airbag stored condition 30, is stored within an airbag module 46 mounted to the roof rail 28. A slotted guide 72, or pair of slotted guides, formed in the airbag module 46 allows the wing elements 48,50 to extend from the airbag module 46 in the transverse directions 52,54 for mounting to the vehicle roof 24 even while the airbag 20 is in the airbag stored condition 30. The first wing element 48 and second wing element 50 can be stored within a slotted chamber 74 formed in the vehicle roof 24, such as in the headliner, such that they are hidden from view while in their respective first wing stored condition 76 and second wing stored condition 78. Upon inflation of the airbag 20, the first and second wing elements 48,50 are pulled downward into a first wing deployed position 80 and second wing deployed position 82 (see FIG. 2). The material of the wing elements 48,50 is thereby stretched to form a trampoline surface 56 that, as trampolines do, absorbs momentum efficiently. While particular embodiments of the invention have been shown and described, numerous variations and alternative embodiments will occur to those skilled in the art. Accordingly, it is intended that the invention be limited only in terms of the appended claims.

<SOH> BACKGROUND OF INVENTION <EOH>The present invention relates generally to an overhead automotive airbag assembly and more particularly to an overhead airbag assembly with limited forward movement. Automotive vehicle design is governed by the constant and unending pursuit of improved occupant comfort and safety. Modern vehicles incorporate considerable design and manufacturing efforts to minimize injuries to occupants in the event of vehicle accidents. These safety features, however, must co-exist with the primary functional features as well as the comfort features of the vehicle. Their placement within the vehicle, therefore, must be a function of both operation of the safety component in combination with available placement within the existing vehicle operational structure. These physical placement constraints can serve to limit the freedom of placement of certain features within the automobile. Such is the case with airbag assemblies. Airbag assemblies have proven themselves to be highly beneficial and desirable to consumers. A wide variety of implementation schemes have been devised in order to improve the functionality of airbag protection assemblies. The assemblies, however, are often positioned within traditional mounting structures based upon their operational objectives. Frontal impact airbags, for instance, are commonly positioned immediately forward of the occupant and are designed to inflate towards the occupant upon vehicle impact. This requires installation immediately forward of the occupant in the steering wheel or dashboard. Placement of frontal impact airbags for rear-seated passengers is often impractical or overly complex. The resulting design scenario commonly finds these airbag assemblies positioned in these traditional mounting locations. These locations, especially the dashboard, can become prized real estate in automotive design. As additional technology and features are incorporated into automobiles, locations such as the dashboard are desirable for passenger accessible features. Present airbag assemblies can place considerable constraint on the incorporation of these new features. It would therefore, be highly desirable to afford an alternate mounting location for forward impact airbag assemblies that provided design flexibility to automotive designers such that that airbag assemblies did not place unreasonable constraints on design creativity. On approach to the placement of frontal impact airbag assemblies is to position the assemblies in an overhead position. This arrangement not only addresses the concern for useful real estate on the dashboard, but also can provide access to passengers seated in the rear without complex seat/airbag designs. The nature of present airbag assemblies, however, does not provide adequate restraint in directions perpendicular to inflation. An overhead airbag assembly, therefore, would provide insufficient resistance to forward motion since the passenger is moving in a direction perpendicular to inflation. The lack of forward motion resistance is further exacerbated by the relatively small airbag mounting arrangements. The mounting structures are commonly small compared to the inflated bags and therefore provide inadequate support for the resistance of perpendicular forces. It would, therefore, be highly desirable to have an overhead airbag assembly design with improved forward motion resistance.

<SOH> SUMMARY OF INVENTION <EOH>It is, therefore, an object of the present invention to provide an automotive overhead airbag assembly with forward motion resistance. It is a further object of the present invention to provide an automotive overhead airbag assembly with improved overhead installation characteristics. In accordance with the objects of the present invention, an automotive overhead airbag assembly is provided. The automotive overhead airbag assembly includes an airbag mounted on an inside surface of a vehicle roof at an airbag mount position. The airbag has an airbag stored condition and an airbag deployed position and expands downwards from said vehicle roof when in the airbag deployed position. The assembly includes at least one wing element having a first wing mounting edge mounted to the vehicle roof and a second wing mounting edge mounted to a lower deployed portion of said airbag. The first wing mounting edge extends in a transverse direction from the airbag mount position. The at least one wing element includes a wing stored condition and a wing deployed position. The at least one wing element restricts forward motion of the airbag when the airbag is in the deployed position. The assembly includes a trampoline surface formed by the at least one wing element when the at least one wing element is in said wing deployed position. The trampoline surface absorbs passenger forward momentum during vehicle impact. Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.

20040525

20061226

20051215

68838.0

FLEMING, FAYE M

OVERHEAD AUTOMOTIVE AIRBAG DESIGN

UNDISCOUNTED

ACCEPTED

ACCEPTED

[HOLDER OF PHOTOMASK]

The present invention relates to an apparatus of holder of photomask for holding the photomask, which is placed in the transfer box and to be exposed by projecting light during process of manufacturing semiconductor, and more particularly to one being able to prevent the photomask from friction with the protrusions therein in consequence of not creating any dust particle. The holder is made of material of PEEK or VESPEL, which is abrasion resisting and high hardness. On the side of the protrusion is shaped in inclination toward center with the top in long cambered surface as supporting ridge. And, at distal end of the supporting ridge, a pedestal is given to jointly integrate with the holder so that the photomask can be placed thereon. Thus, by means of the supporting ridge with the long cambered surface of the protrusion to uphold photo mask, the contacting area of friction is reduced. Moreover, the characteristics of the protrusion is abrasion resisting and high hardness prevent from friction with the Chromium (Cr) deposition on the bottom surface of the photomask therein in consequence of not creating any dust particle.

1. An apparatus of holder of photomask means a holder being able to prevent the photomask from friction with the protrusions therein in consequence of not creating any dust particle. 2. The holder features that the protrusion is made of PEEK material with attrition resisting and high hardness. 3. On the side of the protrusion is shaped in inclination toward center with the top in long cambered surface as supporting ridge. 4. The protrusion can be inserted into the through hole of the holder to let the photomask dispose hereon. And, by means of the supporting ridge with the long cambered surface of the protrusion to uphold photomask, the contacting area of friction is reduced. 5. Thus, it prevents from contact with the Chromium (Cr) deposition on the bottom surface of the photomask therein to avoid attrition of the protrusion creating any dust particle. 6. A holder of photomask as claimed in claim 1, wherein the protrusion is also made of VESPEL material with attrition resisting and high hardness. 7. A holder of photomask as claimed in claim 1, wherein the shape of the pedestal at the distal end of the supporting ridge on the protrusion can be adapted to match the structure of the through hole on the holder. 8. A holder of photomask as claimed in claim 1, wherein a pedestal, at distal end of the supporting ridge, is given to jointly integrate with the through hole of the holder.

CROSS REFERENCE TO RELATED APPLICATIONS This application claims the priority bnefit of Taiwan patent application unmber 092114456 filed on May 8, 2003. BACKGROUND OF INVENTION 1.Field of the Invention The present invention provides an apparatus of holder of photomask for holding the photomask, which is placed in the transfer box and to be exposed by projecting optical light during process of manufacturing semiconductor. By means of the long cambered surface of the protrusion to uphold photo mask, it prevents the protrusion from friction that with the Chromium (Cr) deposition on the bottom surface of the photomask therein in consequence of not creating any dust particle. 2. Description of the Related Art Heretofore, a conventional holder 10 of the photomask 201 (as illustrated in FIGS. 1 & 2) is placed in a base 20 of the transfer box. The holder 10 is U-shaped with several falciform members 101 and several protrusions 102. The holder 10 is made of plastics in one-piece by eject forming, and the protrusion 102 is rendered to uphold photomask 201. As the contacting area of top of the protrusion 102 with photo mask 201 is rather large and in plastics constitution, the protrusion 102 is not featured with attrition resisting and high hardness. Frequently, owing to inspection manipulating in movement and reposition as well as pick-and-place of photomask 201 on holder 10 in process operation, the protrusion 102 is subject to friction with the Chromium (Cr) deposition on the bottom surface of the protrusion 102, which served as circuit protecting shroud layer, and results in creating dust particle. Wherein the Chromium (Cr) deposition on the bottom surface is extremely precise circuit protecting shroud layer so joint with a jacket membrane 201a to stop the dust particle off the focus of photomask 201. If the surface of the jacket membrane 201a is adhered dust particle abundantly, the jacket membrane 201a must be replaced to prevent wafer from failure in exposure. However, the unit price of jacket membrane 201a is expensive so that draw-back in cost increasing due to step up the replacement frequency of jacket membrane 201a as failure in reducing the possibility of friction. That friction occurs between the holder 10 and the photomask 201 in consequence of causing dust particle. Furthermore as shown in FIGS. 1, 2 and 3 respectively, those are a perspective view, a front sectional view and a testing waveform chart of photo mask holder. The friction between the protrusion 101 and photomask 201, it make the protrusion 101 have been wearied and abraded to cause dust particle, then the dust particle creates the unbalance and unflatness of the photomask 201 on the protrusion 101. Thus, it necessitate the repeated adjusting the coordinating position of sucking disk with the photomask 201 to let robot arm use sucking disk to attract the photomask 201 successfully and movement in clean room. If the coordinating position of sucking disk with the photomask 201 is not well adjusted, the sucking disk cannot suck the photomask 201 to move and after a certain period of inspecting process, it can be seen that the seriously unbalanced situation of the protrusion 101 due to the dust particle created by abrading the protrusion 101. And, the testing waveform chart presents some pulsation in big amplitude and to retard the movement in process of photomask 201. Moreover, the transfer box is functioned to ensure the cleanness within be better than that outside. So, the less the dust particle be caused inside, the better is the function. Owing to the current contrived structure, the transfer box is suffered from dust particle of attrition mentioned above. Thus, it creates cost escalation and extra work attributed to periodic cleansing regularly. SUMMARY OF INVENTION The present invention has been accomplished under the circumstances in view. The compound material with high hardness and attrition resisting has been tried. Although the compound material can be able to prevent from causing dust particle in friction, its brittleness is not good enough to form falciform member 101 of the holder 10 through one-piece ejecting forming. It is greatly possible to be cracked and damaged due to shake and crush of the photomask 201. Besides, its cost is rather expensive. From consequence of further experiment, the various materials and adoption of special structure in protrusion is eventually applied to prevent it from friction creating dust particle as well as to reduce the cost. BRIEF DESCRIPTION OF DRAWINGS FIG. 1: is a perspective view of photomask holder with photomask placed hereon of the conventional invention. FIG. 2: is a front sectional view of photomask holder with photomask placed hereon of the conventional invention. FIG. 3: is a testing waveform chart in balanced mode of photomask holder of conventional invention. FIG. 4: is a perspective view of photomask holder of the present invention. FIG. 5: is a front sectional view of photomask holder of the present invention. FIG. 6: is an exploded perspective view of photomask holder in the preferred embodiment of the present invention. FIG. 7: is a testing waveform chart in balanced mode of photomask holder of the present invention. DETAILED DESCRIPTION Referring to FIGS. 4 and 5, which are a perspective view and a front sectional view of photomask holder of the present invention respectively. A protrusion 40 is made from PEEK and VESPEL material with attrition resisting and high hardness. On the side of the protrusion 40 is shaped in inclination toward center with the top in long cambered surface as supporting ridge 41. And, at distal end of the supporting ridge 41, a pedestal 40a is given to jointly integrate with a through hole 50a of a holder 50 so that the protrusion 40 is positioned on the holder 50 and the photomask 201 can be placed on the supporting portion 41 of the protrusion 40 thereon. Thus, by means of the supporting ridge 41 with the long cambered surface of the protrusion 40 to uphold photomask 201, the contacting area of friction is reduced. Moreover, the protrusion 40 with the characteristics of attrition resisting and high hardness enable the protrusion 40 to prevent from friction with the Chromium (Cr) deposition on the bottom surface of the photomask 201 therein in consequence of not creating any dust particle. Wherein, the shape of pedestal 40a (refer to FIGS. 4 and 6) at the distal end of the supporting ridge 41 on the protrusion 40 can be adapted to match the structure of the through hole 50a on the holder 50. Or, the protrusion 40 can also constructed without pedestal 40a to directly adhere the protrusions 40 on the surface of the holder 50. Further referring to FIGS. 5, 6 and 7, which are a front sectional view, an exploded perspective view and a testing waveform chart in balanced mode of photo mask holder of the present invention respectively. The protrusion 40 is made from material with attrition resisting and high hardness. And, by means of the supporting ridge 41 with the long cambered surface of the protrusion 40 to uphold photomask 201, it can prevent the protrusion 40 from friction with the bottom side of the photomask 201. Then, the supporting ridge 41 of the protrusion 40 is hard to susceptible to causing dust particle and to have a more stability of photomask 201 on the protrusion 40. Thus, it is not necessary to repeated adjust the coordinating position of sucking disk with the photomask 201 to let robot arm use sucking disk to attract the photomask 201 successfully and movement of photomask 201 in clean room. And, the testing waveform charts of photomask 201 present pretty balanced and stable condition with limited tolerance of local pulsation in small amplitude. Thus, it proves that the protrusion 40 creates no dust particle due to suffering from no serious attrition. Additionally, by means of protrusion 40 upholding the photomask 201, it remain the photomask 201 in manner of better balance and stability without any effect in operation of moving the photomask 201. Therefore, the protrusion 40 on the holder 50 of the present invention can definitely offer the effect in stable disposition of photomask 201, as well as prevent the protrusion 40 from dust particle caused by friction. Although a particular embodiment of the invention has described in detail for purpose of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.

<SOH> BACKGROUND OF INVENTION <EOH>1.Field of the Invention The present invention provides an apparatus of holder of photomask for holding the photomask, which is placed in the transfer box and to be exposed by projecting optical light during process of manufacturing semiconductor. By means of the long cambered surface of the protrusion to uphold photo mask, it prevents the protrusion from friction that with the Chromium (Cr) deposition on the bottom surface of the photomask therein in consequence of not creating any dust particle. 2. Description of the Related Art Heretofore, a conventional holder 10 of the photomask 201 (as illustrated in FIGS. 1 & 2 ) is placed in a base 20 of the transfer box. The holder 10 is U-shaped with several falciform members 101 and several protrusions 102 . The holder 10 is made of plastics in one-piece by eject forming, and the protrusion 102 is rendered to uphold photomask 201 . As the contacting area of top of the protrusion 102 with photo mask 201 is rather large and in plastics constitution, the protrusion 102 is not featured with attrition resisting and high hardness. Frequently, owing to inspection manipulating in movement and reposition as well as pick-and-place of photomask 201 on holder 10 in process operation, the protrusion 102 is subject to friction with the Chromium (Cr) deposition on the bottom surface of the protrusion 102 , which served as circuit protecting shroud layer, and results in creating dust particle. Wherein the Chromium (Cr) deposition on the bottom surface is extremely precise circuit protecting shroud layer so joint with a jacket membrane 201 a to stop the dust particle off the focus of photomask 201 . If the surface of the jacket membrane 201 a is adhered dust particle abundantly, the jacket membrane 201 a must be replaced to prevent wafer from failure in exposure. However, the unit price of jacket membrane 201 a is expensive so that draw-back in cost increasing due to step up the replacement frequency of jacket membrane 201 a as failure in reducing the possibility of friction. That friction occurs between the holder 10 and the photomask 201 in consequence of causing dust particle. Furthermore as shown in FIGS. 1, 2 and 3 respectively, those are a perspective view, a front sectional view and a testing waveform chart of photo mask holder. The friction between the protrusion 101 and photomask 201 , it make the protrusion 101 have been wearied and abraded to cause dust particle, then the dust particle creates the unbalance and unflatness of the photomask 201 on the protrusion 101 . Thus, it necessitate the repeated adjusting the coordinating position of sucking disk with the photomask 201 to let robot arm use sucking disk to attract the photomask 201 successfully and movement in clean room. If the coordinating position of sucking disk with the photomask 201 is not well adjusted, the sucking disk cannot suck the photomask 201 to move and after a certain period of inspecting process, it can be seen that the seriously unbalanced situation of the protrusion 101 due to the dust particle created by abrading the protrusion 101 . And, the testing waveform chart presents some pulsation in big amplitude and to retard the movement in process of photomask 201 . Moreover, the transfer box is functioned to ensure the cleanness within be better than that outside. So, the less the dust particle be caused inside, the better is the function. Owing to the current contrived structure, the transfer box is suffered from dust particle of attrition mentioned above. Thus, it creates cost escalation and extra work attributed to periodic cleansing regularly.

<SOH> SUMMARY OF INVENTION <EOH>The present invention has been accomplished under the circumstances in view. The compound material with high hardness and attrition resisting has been tried. Although the compound material can be able to prevent from causing dust particle in friction, its brittleness is not good enough to form falciform member 101 of the holder 10 through one-piece ejecting forming. It is greatly possible to be cracked and damaged due to shake and crush of the photomask 201 . Besides, its cost is rather expensive. From consequence of further experiment, the various materials and adoption of special structure in protrusion is eventually applied to prevent it from friction creating dust particle as well as to reduce the cost.

20040526

20060307

20050113

69679.0

MATHEWS, ALAN A

[HOLDER OF PHOTOMASK]

SMALL

ACCEPTED

ACCEPTED

NON-FUSION SPINAL CORRECTION SYSTEMS AND METHODS

Methods and devices that utilize segmental fixation between several adjacent vertebrae, thus allowing each vertebrae to be adjusted independently, are provided. In general, the device includes a spinal anchoring element that is adapted to seat at least one spinal fixation element, and a closure mechanism that is adapted to mate to the spinal anchoring element to lock the at least one spinal fixation element in a fixed position relative to the spinal anchoring element.

1. A device for treating spinal deformities, comprising: a spinal anchoring element adapted to seat first and second spinal fixation elements at a distance spaced apart from one another; and a closure mechanism adapted to mate to the spinal anchoring element to lock each of the first and second spinal fixation elements in a fixed position relative to the spinal anchoring element. 2. The device of claim 1, wherein the spinal anchoring element includes a first recess adapted to receive a first spinal fixation element, and a second recess spaced a distance apart from the first recess and adapted to receive a second spinal fixation element. 3. The device of claim 2, wherein the spinal anchoring element includes a central portion positioned between the first and second recesses and adapted to receive a fastening element for mating the anchoring element to bone. 4. The device of claim 3, wherein the central portion includes a bore extending therethrough for receiving a fastening element. 5. The device of claim 4, wherein the closure mechanism includes a central portion adapted to receive a locking mechanism for mating the closure mechanism to the spinal anchoring element. 6. The device of claim 5, further comprising a fastening element for mating the spinal anchoring element to bone, and a locking mechanism for mating the closure mechanism to the spinal anchoring element. 7. The device of claim 6, wherein the fastening element comprises a bone screw, and the locking mechanism comprises a set screw. 8. The device of claim 3, wherein the first recess is formed in a first end portion of the spinal anchoring element and the second recess is formed in a second, opposed end portion of the spinal anchoring element. 9. The device of claim 8, wherein each end portion includes a superior surface and an inferior surface, the first and second recesses being formed in the superior surface. 10. The device of claim 9, further comprising a bone engaging member extending distally from the inferior surface of each of the first and second end portions. 11. The device of claim 10, wherein each bone engaging member comprises a spike adapted to extend into bone to prevent rotation of the spinal anchoring element. 12. The device of claim 8, wherein the closure mechanism includes a first end portion adapted to lock a spinal fixation element within the first recess, and a second end portion adapted to lock a spinal fixation element within the second recess. 13. The device of claim 12, wherein the first and second ends portions on the closure mechanism each include a bore formed therethrough for receiving an engagement mechanism adapted to extend into and engage a spinal fixation element disposed within each of the first and second recesses in the spinal anchoring element. 14. The device of claim 13, further comprising first and second engagement mechanisms, each engagement mechanism including a proximal, threaded portion adapted to mate with corresponding threads formed within the bore in the closure mechanism, and a distal pin member adapted to extend into a spinal fixation element positioned in each of the first and second recesses. 15. The device of claim 1, further comprising first and second spinal fixation elements adapted to be disposed between the spinal anchoring element and the closure mechanism. 16. The device of claim 15, wherein each spinal fixation element comprises a flexible fixation element. 17. The device of claim 15, wherein each spinal fixation element is formed from a bioabsorbable material. 18. The device of claim 2, wherein each recess has a substantially concave shape. 19. The device of claim 2, wherein each recess includes at least one protrusion formed therein and adapted to extend into and engage a spinal fixation element positioned therein. 20. The device of claim 2, wherein the closure mechanism includes at least one protrusion formed thereon and adapted to extend into and engage a spinal fixation element disposed in each of the first and second recesses formed in the spinal anchoring element. 21. A medical system for treating spinal deformities, comprising: first and second flexible spinal fixation elements; a plurality of spinal anchoring devices adapted to mate to a plurality of vertebrae and to engage the first and second spinal fixation elements such that the first and second spinal fixation elements can be tensioned between the plurality of spinal anchoring devices to adjust a position of the plurality of vertebrae in both a sagittal plane and a coronal plate when the plurality of spinal anchoring devices are implanted in a plurality of vertebrae. 22. The system of claim 21, wherein at least one of the plurality of spinal anchoring devices includes a spinal anchoring element and a closure mechanism adapted to mate to the spinal anchoring element to lock the first and second flexible spinal fixation elements therein. 23. The system of claim 22, wherein the spinal anchoring element and the closure mechanism each include first and second recesses formed therein for seating the first and second spinal fixation elements therebetween. 24. The system of claim 23, wherein the closure mechanism includes first and second bores formed therein and configured to receive an engagement mechanism adapted to extend into and engage the first and second spinal fixation elements. 25. The system of claim 23, wherein the first recess in each of the spinal anchoring element and closure mechanism is spaced a distance apart from the second recess in each of the spinal anchoring element and closure mechanism. 26. The system of claim 25, further comprising a bore extending through the closure mechanism and spinal anchoring element for receiving a fastening element adapted to mate the spinal anchoring element to bone, and a locking mechanism adapted to mate the closure mechanism to the spinal anchoring element. 27. The system of claim 26, wherein the fastening element comprises a bone screw, and the locking mechanism comprises a set screw. 28. The system of claim 26, wherein the bore in the closure mechanism and spinal anchoring element is positioned between the first and second recesses. 29. The system of claim 25, wherein the first recess is formed in a first end portion of each of the spinal anchoring element and the closure mechanism, and the second recess is formed in a second, opposed end portion of each of the spinal anchoring element and the closure mechanism. 30. The system of claim 29, wherein the first and second recesses have a substantially concave shape. 31. The system of claim 29, wherein the recesses are formed in an inferior surface of the closure mechanism and a superior surface of the spinal anchoring element. 32. The system of claim 31, wherein the first and second recesses in at least one of each closure mechanism and each spinal fixation element includes at least one protrusion formed therein for extending into and engaging the first and second spinal fixation elements. 33. The system of claim 21, further comprising at least one bone engaging member formed on at least one of the plurality of spinal anchoring devices for extending into bone to prevent rotation of the spinal anchoring device relative thereto. 34. The system of claim 21, wherein the first and second spinal fixation elements are flexible. 35. The system of claim 21, wherein the first and second spinal fixation elements are formed from a bioabsorbable material. 36. A non-fusion spinal anchoring device for treating spinal deformities, comprising: an anchoring element adapted to seat an elongate element; an engagement mechanism adapted to mate to the anchoring element to seat an elongate element within the anchoring element; and at least one protrusion formed on at least one of the anchoring element and the engagement mechanism for extending into and engaging an elongate element disposed within the anchoring element to prevent sliding movement of the elongate element relative to the anchoring element and the engagement mechanism. 37. The device of claim 36, wherein the elongate element is flexible. 38. The device of claim 36, wherein the engagement mechanism includes a proximal threaded portion adapted to mate with corresponding threads formed on the anchoring element, and wherein the at least one protrusion extends distally from the proximal threaded portion. 39. The device of claim 38, wherein the anchoring element includes a proximal U-shaped member defining a recess for seating an elongate element, and a distal bone-engaging portion. 40. The device of claim 39, wherein the distal bone-engaging portion comprises a bone screw. 41. The device of claim 39, wherein the proximal U-shaped member includes threads formed therein for mating with the proximal threaded portion of the engagement mechanism. 42. The device of claim 36, wherein the engagement mechanism includes a single protrusion formed thereon in the form of a spike. 43. A non-fusion spinal anchoring device for treating spinal deformities, comprising: a spinal anchoring element adapted to seat first and second spinal fixation elements; at least one closure mechanism adapted to mate to the spinal anchoring element to lock the first and second spinal fixation elements therein; and at least one protrusion formed on at least one of the spinal anchoring element and the at least one closure mechanism and effective to prevent sliding movement of the first and second spinal fixation elements relative to the spinal anchoring element. 44. The device of claim 43, further comprising at least one bone-engaging member formed on the spinal anchoring element and adapted to extend into bone to prevent rotation of the spinal anchoring element relative to the bone. 45. A method for correcting spinal deformities, comprising: implanting a plurality of anchoring devices within a plurality of adjacent vertebrae in a spinal column; coupling first and second elongate elements to the plurality of anchoring devices such that the first and second elongate elements are spaced a distance apart from one another; and locking the first and second elongate elements relative to the plurality of anchoring devices to selectively tension the first and second elongate elements between the plurality of anchoring devices, thereby adjusting a position of the plurality of adjacent vertebrae in the spinal column relative to one another. 46. The method of claim 45, wherein the plurality of adjacent vertebrae are adjusted along both a sagittal plane and a coronal plane of a patient's body. 47. The method of claim 45, wherein at least one of the plurality of anchoring devices includes a spinal anchoring element and a closure mechanism adapted to mate to the spinal anchoring element to lock the first and second elongate elements therein. 48. The method of claim 47, wherein the spinal anchoring element and the closure mechanism each include first and second recesses formed therein for seating the first and second spinal fixation elements therebetween. 49. The method of claim 45, wherein the first and second elongate elements are flexible. 50. The method of claim 49, wherein the anchoring device includes at least one protrusion that is adapted to extend into the first elongate element and at least one protrusion that is adapted to extend into the second elongate element, the protrusions being effective to prevent sliding movement of the elongate elements relative to each anchoring device. 51. A non-fusion method for correcting spinal deformities, comprising: implanting a plurality of spinal anchoring devices in a plurality of vertebrae, and fixedly coupling first and second fixation flexible fixation elements to the plurality of spinal anchoring devices such that segmental tension is applied between the anchoring devices to adjust a position of the plurality of vertebrae in both a coronal plane and a sagittal plane of a patient's body. 52. The method of claim 51, wherein at least one of the plurality of spinal anchoring devices includes an anchoring element adapted to mate to a vertebra, and a closure mechanism adapted to lock each of the first and second flexible fixation elements in a fixed position relative to the anchoring element.

FIELD OF THE INVENTION The present invention relates to non-fusion methods and devices for correcting spinal deformities. BACKGROUND OF THE INVENTION Spinal deformities, which include rotation, angulation, and/or curvature of the spine, can result from various disorders, including, for example, scoliosis (abnormal curvature in the coronal plane of the spine), kyphosis (backward curvature of the spine), and spondylolisthesis (forward displacement of a lumbar vertebra). Early techniques for correcting such deformities utilized external devices that apply force to the spine in an attempt to reposition the vertebrae. These devices, however, resulted in severe restriction and in some cases immobility of the patient. Thus, to avoid this need, several rod-based techniques were developed to span across multiple vertebrae and force the vertebrae into a desired orientation. In rod-based techniques, one or more rods are attached to the vertebrae at several fixation sites to progressively correct the spinal deformity. The rods are typically pre-curved to a desired adjusted spinal curvature. Wires can also be used to pull individual vertebra toward the rod. Once the spine has been substantially corrected, the procedure typically requires fusion of the instrumented spinal segments. While several different rod-based systems have been developed, they tend to be cumbersome, requiring complicated surgical procedures with long operating times to achieve correction. Further, intraoperative adjustment of rod-based systems can be difficult and may result in loss of mechanical properties due to multiple bending operations. Lastly, the rigidity and permanence of rigid rod-based systems does not allow growth of the spine and generally requires fusion of many spine levels, drastically reducing the flexibility of the spine. Accordingly, there remains a need for improved methods and devices for correcting spinal deformities, and in particular, there remains a need for non-fusion spinal correction systems and methods. BRIEF SUMMARY OF THE INVENTION The present invention provides methods and devices for treating spinal deformities. In general, the methods and devices utilize segmental fixation between several adjacent vertebrae, thus allowing each vertebrae to be repositioned independently. In one embodiment, a device is provided having a spinal anchoring element that is adapted to seat first and second spinal fixation elements at a distance spaced apart from one another, and a closure mechanism that is adapted to mate to the spinal anchoring element to lock each of the first and second spinal fixation elements in a fixed position relative to the spinal anchoring element. Each spinal fixation element can be, for example, a flexible fixation element that is preferably formed from a bioabsorbable material. The spinal anchoring element can have a variety of configurations, but in an embodiment it includes a first recess that is adapted to receive a first spinal fixation element, and a second recess that is spaced a distance apart from the first recess and that is adapted to receive a second spinal fixation element. The first recess can be formed in a first end portion of the spinal anchoring element and the second recess can be formed in a second, opposed end portion of the spinal anchoring element, and each recess is preferably formed in a superior surface of the anchoring element. A central portion can be formed between the first and second recesses for receiving a fastening element for mating the anchoring element to bone. In an exemplary embodiment, the central portion includes a bore extending therethrough for receiving a fastening element, such as a bone screw. The closure mechanism that mates to the anchoring element can also have a variety of configurations, but in an embodiment it includes a central portion that is adapted to receive a locking mechanism, such as a set screw, for mating the closure mechanism to the spinal anchoring element. The closure mechanism can also include a first end portion that is adapted to lock a spinal fixation element within the first recess, and a second end portion that is adapted to lock a spinal fixation element within the second recess. In one embodiment, the first and second ends portions on the closure mechanism can include a bore formed therethrough for receiving an engagement mechanism that is adapted to extend into and engage a spinal fixation element disposed within each of the first and second recesses in the spinal anchoring element. Each engagement mechanism can include, for example, a proximal, threaded portion that is adapted to mate with corresponding threads formed within the bore in the closure mechanism, and a distal pin member that is adapted to extend into a spinal fixation element positioned in each of the first and second recesses in the anchoring element. In another embodiment, the closure mechanism can include at least one protrusion formed thereon and adapted to extend into and engage a spinal fixation element disposed in each of the first and second recesses formed in the spinal anchoring element. In yet another embodiment, the device can include a bone engaging member extending distally from the inferior surface of each of the first and second end portions of the anchoring element. The bone engaging member can be, for example, a spike that is adapted to extend into bone to prevent rotation of the spinal anchoring element. The present invention also provides a medical system for treating spinal deformities that includes first and second flexible spinal fixation elements, and several spinal anchoring devices. Each anchoring device is adapted to mate to a vertebra and to engage each of the first and second spinal fixation elements such that the first and second spinal fixation elements can be tensioned between each spinal anchoring device to adjust a position of each vertebra in both a sagittal plane and a coronal plate when the spinal anchoring devices are implanted in several adjacent vertebrae. The system can also include several closure mechanisms that are adapted to mate to the spinal anchoring elements to lock the first and second flexible spinal fixation elements therein. In other aspects of the invention, a non-fusion spinal anchoring device for treating spinal deformities is provided having an anchoring element that is adapted to seat an elongate element, such as a flexible fixation element, and an engagement mechanism that is adapted to mate to the anchoring element. The engagement mechanism includes at least one protrusion formed thereon for extending into and engaging an elongate element disposed within the anchoring element to prevent sliding movement of the elongate element relative to the anchoring element. In an exemplary embodiment, the engagement mechanism includes a proximal threaded portion that is adapted to mate with corresponding threads formed on the anchoring element. The protrusion(s) preferably extends distally from the proximal threaded portion. Methods for correcting spinal deformities are also provided. In one embodiment, the method includes the steps of implanting an anchoring device within each of a plurality of adjacent vertebrae in a spinal column, coupling first and second elongate elements to each anchoring device such that the first and second elongate elements are spaced a distance apart from one another, and locking the first and second elongate elements relative to each anchoring device to selectively tension the first and second elongate elements between each anchoring device, thereby adjusting a position of the plurality of adjacent vertebrae in the spinal column relative to one another. The vertebrae are preferably adjusted along both a sagittal plane and a coronal plane of a patient's body. In another non-fusion method for correcting spinal deformities, a spinal anchoring device is implanted in each of a plurality of vertebrae, and first and second flexible fixation elements are fixedly coupled to each spinal anchoring device such that segmental tension is applied between each anchoring device to adjust a position of each of the plurality of vertebrae in both a coronal plane and a sagittal plane of a patient's body. Each anchoring device can include an anchoring element that is adapted to mate to a vertebra, and a closure mechanism that is adapted to lock each of the first and second flexible fixation elements in a fixed position relative to the anchoring element. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. 1 is perspective view illustration of one embodiment of a spinal anchoring device in accordance with the present invention; FIG. 2A is a side, cross-sectional view of an alternative embodiment of the spinal anchoring device shown in FIG. 1; FIG. 2B is a side, cross-sectional view of another alternative embodiment of the spinal anchoring device shown in FIG. 1; FIG. 2C is a side, cross-sectional view of yet another alternative embodiment of the spinal anchoring device shown in FIG. 1; FIG. 3A is a cross-sectional view of the spinal anchoring device shown in FIG. 1 implanted in a vertebra; FIG. 3B is perspective view illustration of several spinal anchoring systems, as shown in FIG. 1, implanted along a portion of a human spinal column in accordance with another embodiment of the present invention; FIG. 4A is a side, disassembled view of another embodiment of a spinal anchoring device in accordance with the present invention; FIG. 4B is a side assembled view of the device shown in FIG. 4A; FIG. 4C is a cross-sectional view of the device shown in FIG. 4B taken across line A-A; FIG. 4D is a cross-sectional view of the device shown in FIG. 4B taken across line B-B; FIG. 5 is a cross-sectional view of yet another embodiment of a spinal anchoring device having inner and outer locking mechanisms; FIG. 6 is a cross-sectional view of another embodiment of a spinal anchoring device having two inner locking mechanisms; FIG. 7A is a top perspective view of a portion of a spinal anchoring device having several protrusions formed thereon in accordance with yet another embodiment of the present invention; FIG. 7B is a top view of the spinal anchoring element shown in FIG. 7A with a locking mechanism disposed therein; FIG. 8A is a perspective view of a deformed human spinal column having multiple spinal anchoring devices, as shown in FIGS. 4A-4C, implanted therein and mated to one another by first and second spinal fixation elements in accordance with another embodiment of the present invention; FIG. 8B is a perspective view of the human spinal column shown in FIG. 8A after the deformity is corrected; FIG. 9 is a perspective view of a portion of a deformed human spinal column having multiple spinal anchoring devices, as shown in FIGS. 4A-4C, implanted therein in accordance with yet another embodiment of the present invention; FIG. 10A is a side perspective view of yet another embodiment of a spinal anchoring device in accordance with the present invention; and FIG. 10B is a side perspective view of a spinal anchoring device in accordance with yet another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION The present invention provides methods and devices for treating spinal deformities, and in particular to non-fusion methods and devices for treating spinal deformities. In general, the methods and devices utilize segmental fixation between several adjacent vertebrae, thus allowing each vertebrae to be adjusted independently. The vertebrae can be individually adjusted along both the coronal plane and the sagittal plane of the patient's body. Such a technique can be advantageous for shortening and/or halting growth of the patient's spine, however the methods and devices can be used in a variety of other spinal applications. By way of non-limiting example, the device can be used for posterior dynamization to function as a decompressive device for stenosis and/or an adjunct to an intervertebral disc to unload the facets of the vertebra. FIG. 1 illustrates one embodiment of a spinal anchoring device 10 in accordance with the present invention. As shown, the spinal anchoring device 10 includes a spinal anchoring element 12 that is adapted to seat first and second spinal fixation elements 14a, 14b at a distance spaced apart from one another, and a closure mechanism 16 that is adapted to mate to the spinal anchoring element 12 to lock each of the first and second spinal fixation elements 14a, 14b in a fixed position relative to the spinal anchoring element 12. The device 10 can also include a fastening element 20 for mating the spinal anchoring element 12 to bone, and a locking mechanism 18 for mating the closure mechanism 16 to the spinal anchoring element 12. While not illustrated, a single fastening element can be used to attach the anchoring element to bone and to lock the closure mechanism to the anchoring element. A person skilled in the art will appreciate that the spinal anchoring device 10 can be used with a variety of spinal fixation elements, and by way of non-limiting example, suitable fixation elements include rigid or flexible spinal rods, cables, tethers, wires, etc. The fixation elements can also be formed from a variety of materials, including, for example, stainless steel, titanium, non-absorbable polymeric braided materials, such as ultra-high molecular weight polyethylene or poly(ethylene terephthalate), absorbable polymeric braided materials, such as poly(L-lactic acid) or other high strength, slowly degrading polymers known in the art. The spinal anchoring element 12 can have a variety of configurations, but, as stated above, it should be adapted to seat first and second spinal fixation elements 14a, 14b therein. In an exemplary embodiment, as shown, the anchoring element 12 is in the form of a generally elongate housing having opposed superior and inferior surfaces 12s, 12i, and opposed first and second ends 12a, 12b. The inferior surface 12i is adapted to be positioned against bone when the spinal anchoring element 12 is implanted, and the superior surface 12s is adapted to seat the first and second fixation elements 14a, 14b. Accordingly, the superior surface 12s can include first and second opposed recesses 22a, 22b formed therein adjacent the opposed first and second ends 12a, 12b thereof for seating the spinal fixation elements 14a, 14b. The recesses 22a, 22b are spaced a distance apart from one another to allow the fixation elements 14a, 14b to be positioned at different locations along the patient's spinal column, as will be discussed in more detail below. Each recess 22a, 22b can vary in shape and size depending on the configuration of the fixation element 14a, 14b being disposed therein, but in an exemplary embodiment each recess 22a, 22b has a substantially convex shape. The recesses 22a, 22b also preferably extend across the superior surface 12s of the anchoring element 12 in a direction that is substantially transverse to an axis L that extends between the first and second ends 12a, 12b. As a result, the spinal fixation elements 14a, 14b will extend in the same direction as the recesses 12a, 12b. The spinal anchoring element 12 also preferably includes a central portion 12c that is formed between the opposed ends 12a, 12b and that is adapted to receive a fastening element 20 for mating the spinal anchoring element 12 to bone. While other techniques can be used to mate the anchoring element 12 to bone, and the anchoring element 12 can be mated at other locations on the device 10, in an exemplary embodiment the central portion 12c includes a central pathway or bore 12d extending therethrough for receiving the fastening element 20. The central bore 12d can vary in shape and size depending on the configuration of the fastening element 20. However, in an exemplary embodiment, the fastening element 20 is a bone screw having a head 20a and a threaded shank 20b, and the bore 12d includes a distal portion or recess 12d2 that is adapted to seat the head 20a of the bone screw 20 such the shank 20b of the bone screw 20 extends through the bore 12d. In other words, the bone screw 20 can be polyaxial relative to the anchoring element 12. In use, the bone screw 20 can be inserted through the bore 12d and threaded into bone, thereby attaching the anchoring element 12 to bone. A person skilled in the art will appreciate that, while a polyaxial bone screw 20 is shown, the bone screw 20 can be monoaxial or it can have a variety of other configurations. Other techniques for attaching the anchoring element 12 to bone may also be used. The spinal anchoring element 12 can also optionally include one or more bone-engaging members formed thereon and adapted to prevent rotational movement of the anchoring element 12 when the anchoring element 12 is implanted. FIG. 1 illustrates one exemplary embodiment of first and second bone-engaging members 24a, 24b formed on and extending distally from the inferior surface 12i of the anchoring element 12 at a location adjacent to the first and second ends 12a, 12b of the anchoring element 12. The bone-engaging members 24a, 24b are in the form of spikes that are adapted to extend into bone, however they can have a variety of other shapes. In use, a mallet or other device can be used to apply a force to the anchoring element 12 to impact the spikes 24a, 24b into bone at the desired implant site. The fastening element, e.g., bone screw 20, can then be inserted through the central bore 12d and threaded into bone to further secure the anchoring element 12 to the bone. Still referring to FIG. 1, the device 10 also includes a closure mechanism 16 that is adapted to mate to the spinal anchoring element 12 to lock each of the first and second spinal fixation elements 14a, 14b in a fixed position relative to the spinal anchoring element 12. The configuration of the closure mechanism 16 can vary, and it can be formed from separate components, but more preferably it is formed from a single elongate member having a shape that is substantially similar to the shape of the anchoring element 12. As shown in FIG. 1, the closure mechanism 16 includes first and second opposed ends 16a, 16b that are configured to be juxtapositioned on the first and second opposed ends 12a, 12b of the anchoring element 12. The closure mechanism 16 also includes superior and inferior surfaces 16s, 16i. The inferior surface 16i, which is the surface that faces the superior surface 12s of the anchoring element 12, is adapted to lock the first and second fixation elements 14a, 14b within the recesses 22a, 22b formed in the anchoring element 12. Accordingly, the inferior surface 16i can include first and second recesses 26a, 26b formed therein and opposed to the first and second recesses 22a, 22b in the anchoring element 12 to facilitate engagement of the fixation elements 14a, 14b. While the shape of each recess 26a, 26b will vary depending on the shape of each fixation element 14a, 14b, in an exemplary embodiment each recess 26a, 26b preferably has a substantially concave shape such that the opposed recesses 22a, 26a, 22b, 26b in the anchoring element 12 and the closure mechanism 16 form a substantially cylindrical cavity extending therebetween for receiving substantially cylindrical, elongate fixation elements 14a, 14b. Each recess 26a, 26b should also extend in the same direction as the recesses 22a, 22b formed in the anchoring element 12. The closure mechanism 16 can be mated to the spinal anchoring element 12 using a variety of techniques, but in an exemplary embodiment, as shown, the closure mechanism 16 includes a central portion 16c having a central bore 16d extending therethrough for receiving a locking mechanism 18. The central bore 16d is preferably axially aligned with the central bore 12d in the anchoring element 12 to allow the locking mechanism 18 to extend through the closure mechanism 16 and to engage the anchoring element 12. While various types of locking mechanisms can be used, in an exemplary embodiment the locking mechanism 18 is a set screw 18 having a head 18a and a threaded shank 18b. The bore 16d in the closure mechanism 16 is therefore preferably adapted to seat the head 18a of the set screw, yet to allow the threaded shank 18b to pass therethrough. The bore 16d can optionally be tapered from the superior surface 16s to the inferior surface 16i to further facilitate positioning of the head 18a of the set screw 18 therein, and more preferably to allow the head 18a to seat flush or sub-flush with the superior surface 16s of the closure mechanism 16. When the head 18a is seated within the bore 16d in the closure mechanism, the threaded shank 18b of the set screw 18 extends through the bore 16d to engage the anchoring element 12. The bore 12d in the anchoring element 12 is thus preferably adapted to mate with the threaded shank 18d to allow the set screw 18 to lock the closure mechanism 16 to the anchoring element 12, thereby locking the first and second fixation elements 14a, 14b within the recesses 22a, 22b, 26a, 26b in the closure mechanism 16 and anchoring element 12. As shown in FIG. 1, a proximal portion 12d1 of the bore 12d in the anchoring element 12 is threaded to mate with the threaded shank 18b of the set screw 18. A person skilled in the art will appreciate that a single fastening element can be used to lock the closure mechanism 16 to the anchoring element 12, and to also attach the anchoring element 12 to bone. In use, when the set screw 18 is fully threaded into the bore 12d in the anchoring element 12, the closure mechanism 16 is locked to the anchoring element 12, thereby locking the first and second fixation elements 14a, 14b therebetween. Where the bone screw 20 is polyaxial, the shank 18b of the set screw 18 can be configured to contact the fastening element, e.g., bone screw 20, to lock the bone screw 20 in a fixed position relative to the anchoring element 12. In order to drive the set screw 18 into the anchoring element 12, the set screw 18 can include a mating element, such as a socket 18c, formed on or in the head 18a thereof for mating with or receiving a driver mechanism. A person skilled in the art will appreciate that a variety of other techniques can be used to lock the closure mechanism 16 to the anchoring element 12. The spinal anchoring device 10 can also include a variety of engagement mechanisms that are adapted to engage the first and second fixation elements 14a, 14b to prevent slidable movement of the fixation elements 14a, 14b relative to the closure mechanism 16 and the anchoring element 12 when the closure mechanism 16 is locked to the anchoring element 12. FIGS. 2A-2C illustrate various embodiments of engagement mechanisms for use with the present invention. A person skilled in the art will appreciate that a variety of other techniques can be used to facilitate locking of the first and second fixation elements 14a, 14b within the device 10. FIG. 2A illustrates one embodiment of a spinal anchoring device 10′ having protrusions 28a, 28b formed within the first and second recesses 26a′, 26b′ of the closure mechanism 16′, and FIG. 2B illustrates another embodiment of a spinal anchoring device 10″ having protrusions 30a, 30b formed within the first and second recesses 22a″, 22b″ of the anchoring element 12′. The size and shape of the protrusions 28a, 28b, 30a, 30b can vary, but as shown each protrusion 28a, 28b, 30a, 30b can have a substantially triangular or spiked shape. In use, the protrusions 28a, 28b, 30a, 30b extend into the spinal fixation elements 14a, 14b to engage the spinal fixation elements 14a, 14b. For example, where each fixation element 14a, 14b is formed from a flexible cable or tether, the protrusions 28a, 28b, 30a, 30b will engage the fixation element to prevent it from sliding relative to the device 10′, 10″. A person skilled in the art will appreciate that the closure mechanism 16′, 16″ and/or the anchoring element 12′, 12″ can include any number of protrusions formed therein at any location. FIG. 2C illustrates another embodiment of an engagement mechanism for preventing slidable movement of the fixation elements 14a, 14b within the device 10′″. In this embodiment, the closure mechanism 16′″ includes first and second bores 34a, 34b formed therein for receiving first and second engagement mechanisms 32a, 32b, each of which is adapted to engage the spinal fixation element 14a, 14b disposed between the closure mechanism 16′″ and the anchoring element 12′″. The bores 34a, 34b are preferably threaded, as shown, however they can be adapted to mate with the engagement mechanism 32a, 32b using a variety of other techniques, such as, for example, a snap-fit, an interference fit, etc. Each engagement mechanism 32a, 32b can also have a variety of configurations, but in an exemplary embodiment, as shown, each engagement mechanism 32a, 32b includes a proximal, threaded portion 32a1, 32b1 that is adapted to mate with the threaded bores 34a, 34b in the closure mechanism 16′″, and a distal pin member 32a2, 32b 2 that is adapted to extend into the spinal fixation element 14a, 14b positioned between the closure mechanism 16′″ and the anchoring element 12′″. While the distal pin member 32a2′ 32b2 preferably extends into the fixation elements 14a, 14b, where a rigid fixation element is used, the distal pin member 32a2′ 32b2 can use other techniques for engaging the fixation element 14a, 14b, such as an interference fit. The device 10′″ can also include, in combination with the engagement mechanisms 32a, 32b, one or more protrusions (not shown) formed therein and adapted to extend into and/or engage the spinal fixation element 14a, 14b, such as those previously described with respect to FIGS. 2A-2B. FIGS. 3A-3B illustrate an exemplary method for correcting a spinal deformity. Referring to FIG. 3A, spinal anchoring device 10 (shown in FIG. 1) is shown in implanted in a patient's vertebra 60. The spinal anchoring element 12 is first implanted preferably by impacting the anchoring element 12 to insert the bone-engaging members or spikes 24a, 24b into the vertebra 60, thereby positioning the anchoring element 12 at the desired implant site. A fastening element, e.g., bone screw 20, can then be inserted through the bore 12d in the anchoring element 12 and threaded into the vertebra 60 to securely attach the anchoring element 12 to the vertebra 60. The position of the anchoring element 12 relative to the vertebra 60 can vary depending on the spinal deformity being corrected. In FIG. 3A, the anchoring element 12 is implanted in the lateral aspect of the vertebra 60. As shown in FIG. 3B, once the anchoring element 12 is securely attached to the vertebra, several additional anchoring elements 12′, 12″ can be implanted within adjacent vertebrae 60′, 60″ along the patient's spine. The location of the anchoring elements 12, 12′, 12″ along the spine can vary depending on the deformity being corrected. First and second spinal fixation elements, such as fixation elements 14a, 14b, are then positioned with the recess in each anchoring element 12, 12′, 12″ such that the fixation elements 14a, 14b span across several vertebrae 60, 60′, 60″. A closure mechanism 16, 16′, 16″ can then be applied to each anchoring element 12, 12′, 12″ and a locking mechanism, e.g., set screw 18, 18′, 18″ can be loosely threaded to each anchoring element 12, 12′, 12″ to loosely attach the closure mechanisms 16, 16′, 16″ thereto. A tension of the fixation elements 14a, 14b between each device 10, 10′, 10″ can then be adjusted to apply a selected segmental tension, and the tension can be retained by tightening the locking mechanisms 16, 16′, 16″. The selected segmental tension can be configured to intraoperatively achieve correction immediately, or the tension can be configured such that the fixation elements 14a, 14b will asymmetrically restrict growth of the spine to achieve correction. Since the fixation elements 14a, 14b are spaced a distance apart from one another, and since the tension can be adjusted between each device 10, 10′, 10″, the fixation elements 14a, 14b can correct spinal deformities in both the sagittal plane and the coronal plane of the patient's body, i.e., the fixation elements 14a, 14b provide correction in all three rotational degrees of freedom. FIGS. 4A-4D illustrate yet another embodiment of a spinal anchoring device 100 in accordance with the present invention. The spinal anchoring device 100 is similar to spinal anchoring device 10, however it is preferably only adapted to seat a single spinal fixation element 114 therein. As shown in FIG. 4A, the device 100 generally includes an anchoring element 102 that is adapted to seat a fixation element 114, and an engagement mechanism 104 that is adapted to mate to the anchoring element 102 and to engage the fixation element 114 to lock the fixation element 114 within the anchoring element 102. In this embodiment, the device 100 is particularly adapted for use with a flexible fixation element 114. However, a person skilled in the art will appreciate that the device 100 can be modified for use with rigid fixation elements. In use, multiple spinal anchoring devices 100 can be implanted in each vertebra and/or in multiple adjacent vertebrae along a patient's spinal column to provide the desired correction in one or more rotational degrees of freedom. The anchoring element 102 can have virtually any configuration, and it can be in the form of a spinal plate, a monoaxial bone screw, a polyaxial bone screw, a hook, or any other device known in the art for anchoring a spinal fixation element to bone. In the illustrated embodiment, the anchoring element 102 is a monoaxial bone screw having a threaded, bone engaging shank 102b that is coupled to a U-shaped head 102a. The head 102a include opposed recesses 102c1, 102c2 formed therein for receiving the fixation element 114. The head 102a also preferably includes threads (not shown), or some other mating element, formed therein for mating with threads, or some other complementary mating element, formed on the engagement mechanism 104. The engagement mechanism 104 can also have a variety of configurations as long as it is adapted to mate to the anchoring element 102 to lock the fixation element 114 therein. As shown in FIG. 4A, the engagement mechanism 104 includes a proximal, threaded portion that is adapted to mate with corresponding threads formed within the U-shaped head 102a. As previously mentioned, other techniques can be used to mate the engagement mechanism 104 to the U-shaped head 102a, including, for example, a twist-lock closure mechanism, a snap-fit, etc. The engagement mechanism 104 also includes a distal portion 104b that extends distally from the proximal, threaded portion 104a and that is adapted to at least partially extend into the fixation element 114. As shown, the distal portion 104b is in the form of a pin or spike. FIGS. 4A-4D illustrate the device 100 with the flexible fixation element 114 locked therein. As shown, the fixation element 114 is positioned to extend through the recesses 102c1′ 102c2 in the U-shaped head 102a, and the engagement mechanism 104 is threaded into the head 102a to cause the distal pin 104b to penetrate through the fixation element 114. A driver device can be used to engage a mating element, such as a socket 104(c) (FIG. 4C), formed in the proximal threaded portion 104a of the engagement mechanism 104, and to rotate the engagement mechanism 104 to thread it into the anchoring element 102. Once the engagement mechanism 104 is fully threaded into the anchoring element 102, the fixation element 114 is locked in a fixed position such that it is prevented from moving relative to the anchoring element 102. FIGS. 5 and 6 illustrate additional embodiments of engagement mechanisms for locking a fixation element within an anchoring element of a spinal fixation device. In the embodiment shown in FIG. 5, the spinal fixation device 200 includes inner and outer engagement mechanisms 204, 206. The inner engagement mechanism 204 is similar to engagement mechanism 104 shown in FIG. 4A as it includes a proximal threaded portion 204a that is adapted to mate with corresponding threads formed on an internal portion of the U-shaped head 202a of the anchoring element 202, and a distal portion 204b that extends distally from the proximal, threaded portion 204a and that is adapted to at least partially extend into a fixation element 214 seated within the anchoring element 202. The outer engagement mechanism 206 is also threaded and it is adapted to mate with corresponding threads formed on an outer portion of the U-shaped head 202a of the anchoring element 202. In use, the outer engagement mechanism 206 prevents the legs of the U-shaped head 202a from splaying, thereby further locking the spinal fixation element 214 within the U-shaped head 202a. In the embodiment shown in FIG. 6, the spinal fixation device 300 includes two inner engagement mechanisms 304, 306. The first inner engagement mechanism 304 is similar to engagement mechanism 104 shown in FIG. 4A in that it includes a proximal threaded portion 304a and a distal portion 304b that is adapted to extend into a spinal fixation element 314 seated within the spinal anchoring element 302. The proximal threaded portion 304a does not, however, mate with the U-shaped head 302a of the anchoring element 302, but rather it mates with threads formed on an inner surface of the second inner engagement mechanism 306, which in turn includes outer threads formed thereon that mate with the threads formed on the inner surface of the U-shaped head 302a. This allows the second engagement mechanism 306 to be threaded into the U-shaped head 302a to secure the spinal fixation element 314 within the head 302a, yet to allow slidably movement of the spinal fixation element 314. The fixation element 314 can subsequently be locked within the head 302a by threading the first inner engagement mechanism 304 into the second inner engagement mechanism 306, thereby causing the distal portion 304b of the first inner engagement mechanism 304 to extend into the spinal fixation element 314. A person skilled in the art will appreciate that, while threads are shown for mating the engagement mechanisms to the anchoring element, virtually any mating technique can be used including, for example, a twist-lock, a dovetail, a snap-fit, etc. The spinal anchoring devices can also include a variety of other features to prevent slidable movement of a fixation element relative thereto. Suitable engagement features include, for example, protrusions, such as those described with respect to FIGS. 2A-2B, knurling on the surface of each recess, non-slip coatings, and other features known in the art. FIGS. 7A and 7B illustrate yet another embodiment of a spinal anchoring device 400 having three protrusions formed thereon that are adapted to prevent slidable movement of a fixation element relative thereto. In particular, the spinal anchoring device 400, which is similar to anchoring device 100 shown in FIG. 4A, includes a central protrusion 403 extending proximally from a substantial mid-portion of the U-shaped head 402a, and first and second smaller protrusions 405, 407 extending proximally from the recesses 402a1′ 402a2 formed in the U-shaped head 402a. Each of the protrusions 403, 405, 407 is adapted to extend into a spinal fixation element (not shown) seated within the head 402a of the anchoring element 402. The spinal fixation element can then be locked within the head 402a using an engagement mechanism. As shown in FIG. 7B, the engagement mechanism 408 is threaded for mating with corresponding threads formed on the inner surface of the U-shaped head 402a. The engagement mechanism 408 also includes a central lumen 409 extending therethrough for receiving at least a portion of the central protrusion 403. FIGS. 8A-8B illustrate one exemplary method for correcting spinal deformities using a spinal anchoring device, such as device 100 shown in FIGS. 4A-4D. In FIG. 8A, a human spinal column having a right thoraco-lumbar scoliotic deformity is shown, however the methods can be used to correct a variety of spinal deformities. Following standard surgical procedures, the antero-lateral aspect of the thoraco-lumbar spinal vertebrae are exposed. In order to induce correction at each spinal level, several spinal anchoring elements 100(a)-(f) are implanted in one or more adjacent vertebrae, as shown. Radiographs may be obtained to determine the corrective actions needed, and thus to determine the proper placement for each anchoring element 100(a)-(f). As shown in FIG. 8A, three anchors 100(a), 100(b), 100(c) are placed in the sagittal plane on the concave side of the curve in the spinal column, and three additional anchors 100(d), 100(e), 100(f) are placed on the opposed convex side of the spinal column at a higher level than the first three anchors 100(a), 100(b), 100(c). Next, a first fixation element 114(a) is positioned within spinal anchoring devices 100(a), 100(b), 100(c), and a second fixation element 114(b) is positioned within spinal anchoring devices 100(d), 100(e), 100(f). An engagement mechanism can then be at least partially applied to each anchoring device 100(a)-(f) to at least temporarily retain the fixation element 114(a), 114(b) therein, and preferably at least one of the engagement mechanisms on each side of the spine is fully tightened to lock the first and second fixation elements 114(a), 114(b) to one of the anchoring devices, e.g., devices 100(a) and 100(d). The fixation elements 114(a), 114(b) can then be selectively tensioned between each anchoring device 100(a)-(f) by tightening the engagement mechanism at each level. The tension between each vertebra can vary depending on the desired correction, which can be accomplished intraoperatively by tensioning the fixation elements 114(a), 114(b) to achieve the correction immediately, and/or by allowing normal growth of the spine to achieve correction by asymmetrically restricting growth using the fixation elements 114(a), 114(b). FIG. 8B illustrates the spinal column of FIG. 8A with the deformity corrected. Once correction has been achieved, the fixation elements can optionally be cut to release the tension at one or more levels. In one embodiment, the fixation elements can be cut in a minimally invasive procedure. Cutting the fixation elements is particularly advantageous to prevent over-correction. As noted above, the position of each fixation element along the patient's spinal column will vary depending on the spinal deformity being corrected. By way of non-limiting example, as shown in FIG. 9, to achieve correction of a scoliotic deformity in the frontal plane, both fixation elements 114a, 114b can be placed on the convex side of the curve, with one posterior fixation element 114b and one anterior fixation element 114a. The fixation elements 114a, 114b are mated to the vertebrae by several spinal fixation devices 100a, 100b, 100c, 100d, 100e, 100f that are implanted adjacent to one another within each of several adjacent vertebrae (only three vertebrae 160a, 160b, 160c are shown for illustration purposes). Spinal fixation devices 100a, 100c, and 100e are positioned on the anterior side of the vertebrae, and spinal fixation devices 100b, 100d, and 100f are positioned on the posterior side of the vertebrae. Tension can then be applied to both the anterior and posterior fixation elements 114a, 114b by selectively fastening the fixation devices 100a, 100b, 100c, 100d, 100e, 100f to lock the fixation elements 114a, 114b therein. To correct only the frontal plane deformity, equal tension is preferably applied to both fixation elements 114a, 114b, and the degree of tension dictates how much correction is achieved intraoperatively and how much is left to take place during asymmetric growth restriction. To achieve correction of a saggittal plane deformity in addition to correction of a scoliotic deformity, the anterior and posterior fixation elements 114a, 114b are preferably tensioned differently. To increase lordosis, the posterior fixation element 114b is tightened more than the anterior fixation element 114a. To increase kyphosis, the anterior fixation element 114a is tightened more than the posterior fixation element 114b. Similar to correcting the scoliotic deformity, the degree of tension dictates how much correction is achieved intraoperatively and how much is left to take place during asymmetric growth restriction. FIGS. 10A-10B illustrate additional embodiments of spinal anchoring devices 500, 600. In these embodiments, the anchoring devices 500, 600 include a combination of features from anchoring device 10, shown in FIG. 1, and from anchoring device 100 shown in FIG. 4. In particular, each anchoring device 500 includes a spinal anchoring element 512, 612 that is similar to spinal anchoring element 12 shown in FIG. 1. Anchoring elements 512, 612, however, include first and second U-shaped heads 502a, 502b, 602a, 602b formed thereon for seating first and second fixation elements. The heads 502a, 502b, 602a, 602b, which are similar to head 102 in FIG. 4, allow separate engagement mechanisms 504a, 504b, 506a, 506b to be applied thereto to secure the fixation elements separately within the heads 502a, 502b, 602a, 602b. In FIG. 10A, the engagement mechanisms 504a, 504b are similar to engagement mechanism 104 in that they include a proximal portion 504a1′ 504b1 that mates to an internal portion of the U-shaped head 502a, 502b, and a distal portion 504a2′ 504b2 that is adapted to extend into a spinal fixation element to prevent slidably movement of the fixation element relative to the anchoring element 512. In FIG. 10B, the engagement mechanisms 604a, 604b are similar to engagement mechanism 408 shown in FIGS. 8A and 8B in that they each include a central lumen 609a, 609b for receiving a portion of a protrusion 603a, 603b formed within the U-shaped head 602a, 602b, and they are each adapted to threadably mate with an inner surface of each U-shaped head 602a, 602b. In use, the separate engagement mechanisms 504a, 504b, 604a, 604b on each device 500, 600 allow first and second fixation elements disposed within the anchoring elements 512, 612 to be individually tensioned and locked relative to the anchoring element 512, 612, thereby allowing segmental tension to be created between adjacent vertebrae. The following example serves to further illustrate the invention: EXAMPLE 1 A 3 mm Ultra-High Molecular Weight Polyethylene (Spectra) cable was attached to a U-shaped head of a bone screw using a set screw tightened with a torque of 5 N-m. The set screw did not include anything that penetrated into the cable. A second 3 mm Ultra-High Molecular Weight Polyethylene (Spectra) cable was attached to a U-shaped head of a bone screw using an engagement mechanism having a pin that was inserted through the cable. The engagement mechanism was tightened with a torque of 3 N-m. The force required to move each cable was tested. The cable tightened with the set screw required 32 N of force to cause 3 mm of slippage, whereas the cable tightened using the engagement mechanism required 244 N of force to cause 3 mm of slippage. Accordingly, the engagement mechanism with the pin that extended through the cable required 750% more force to move the cable. One of ordinary skill in the art will appreciate further features and advantages of the invention based on the above-described embodiments. Accordingly, the invention is not to be limited by what has been particularly shown and described, except as indicated by the appended claims. All publications and references cited herein are expressly incorporated herein by reference in their entirety.

<SOH> BACKGROUND OF THE INVENTION <EOH>Spinal deformities, which include rotation, angulation, and/or curvature of the spine, can result from various disorders, including, for example, scoliosis (abnormal curvature in the coronal plane of the spine), kyphosis (backward curvature of the spine), and spondylolisthesis (forward displacement of a lumbar vertebra). Early techniques for correcting such deformities utilized external devices that apply force to the spine in an attempt to reposition the vertebrae. These devices, however, resulted in severe restriction and in some cases immobility of the patient. Thus, to avoid this need, several rod-based techniques were developed to span across multiple vertebrae and force the vertebrae into a desired orientation. In rod-based techniques, one or more rods are attached to the vertebrae at several fixation sites to progressively correct the spinal deformity. The rods are typically pre-curved to a desired adjusted spinal curvature. Wires can also be used to pull individual vertebra toward the rod. Once the spine has been substantially corrected, the procedure typically requires fusion of the instrumented spinal segments. While several different rod-based systems have been developed, they tend to be cumbersome, requiring complicated surgical procedures with long operating times to achieve correction. Further, intraoperative adjustment of rod-based systems can be difficult and may result in loss of mechanical properties due to multiple bending operations. Lastly, the rigidity and permanence of rigid rod-based systems does not allow growth of the spine and generally requires fusion of many spine levels, drastically reducing the flexibility of the spine. Accordingly, there remains a need for improved methods and devices for correcting spinal deformities, and in particular, there remains a need for non-fusion spinal correction systems and methods.

<SOH> BRIEF SUMMARY OF THE INVENTION <EOH>The present invention provides methods and devices for treating spinal deformities. In general, the methods and devices utilize segmental fixation between several adjacent vertebrae, thus allowing each vertebrae to be repositioned independently. In one embodiment, a device is provided having a spinal anchoring element that is adapted to seat first and second spinal fixation elements at a distance spaced apart from one another, and a closure mechanism that is adapted to mate to the spinal anchoring element to lock each of the first and second spinal fixation elements in a fixed position relative to the spinal anchoring element. Each spinal fixation element can be, for example, a flexible fixation element that is preferably formed from a bioabsorbable material. The spinal anchoring element can have a variety of configurations, but in an embodiment it includes a first recess that is adapted to receive a first spinal fixation element, and a second recess that is spaced a distance apart from the first recess and that is adapted to receive a second spinal fixation element. The first recess can be formed in a first end portion of the spinal anchoring element and the second recess can be formed in a second, opposed end portion of the spinal anchoring element, and each recess is preferably formed in a superior surface of the anchoring element. A central portion can be formed between the first and second recesses for receiving a fastening element for mating the anchoring element to bone. In an exemplary embodiment, the central portion includes a bore extending therethrough for receiving a fastening element, such as a bone screw. The closure mechanism that mates to the anchoring element can also have a variety of configurations, but in an embodiment it includes a central portion that is adapted to receive a locking mechanism, such as a set screw, for mating the closure mechanism to the spinal anchoring element. The closure mechanism can also include a first end portion that is adapted to lock a spinal fixation element within the first recess, and a second end portion that is adapted to lock a spinal fixation element within the second recess. In one embodiment, the first and second ends portions on the closure mechanism can include a bore formed therethrough for receiving an engagement mechanism that is adapted to extend into and engage a spinal fixation element disposed within each of the first and second recesses in the spinal anchoring element. Each engagement mechanism can include, for example, a proximal, threaded portion that is adapted to mate with corresponding threads formed within the bore in the closure mechanism, and a distal pin member that is adapted to extend into a spinal fixation element positioned in each of the first and second recesses in the anchoring element. In another embodiment, the closure mechanism can include at least one protrusion formed thereon and adapted to extend into and engage a spinal fixation element disposed in each of the first and second recesses formed in the spinal anchoring element. In yet another embodiment, the device can include a bone engaging member extending distally from the inferior surface of each of the first and second end portions of the anchoring element. The bone engaging member can be, for example, a spike that is adapted to extend into bone to prevent rotation of the spinal anchoring element. The present invention also provides a medical system for treating spinal deformities that includes first and second flexible spinal fixation elements, and several spinal anchoring devices. Each anchoring device is adapted to mate to a vertebra and to engage each of the first and second spinal fixation elements such that the first and second spinal fixation elements can be tensioned between each spinal anchoring device to adjust a position of each vertebra in both a sagittal plane and a coronal plate when the spinal anchoring devices are implanted in several adjacent vertebrae. The system can also include several closure mechanisms that are adapted to mate to the spinal anchoring elements to lock the first and second flexible spinal fixation elements therein. In other aspects of the invention, a non-fusion spinal anchoring device for treating spinal deformities is provided having an anchoring element that is adapted to seat an elongate element, such as a flexible fixation element, and an engagement mechanism that is adapted to mate to the anchoring element. The engagement mechanism includes at least one protrusion formed thereon for extending into and engaging an elongate element disposed within the anchoring element to prevent sliding movement of the elongate element relative to the anchoring element. In an exemplary embodiment, the engagement mechanism includes a proximal threaded portion that is adapted to mate with corresponding threads formed on the anchoring element. The protrusion(s) preferably extends distally from the proximal threaded portion. Methods for correcting spinal deformities are also provided. In one embodiment, the method includes the steps of implanting an anchoring device within each of a plurality of adjacent vertebrae in a spinal column, coupling first and second elongate elements to each anchoring device such that the first and second elongate elements are spaced a distance apart from one another, and locking the first and second elongate elements relative to each anchoring device to selectively tension the first and second elongate elements between each anchoring device, thereby adjusting a position of the plurality of adjacent vertebrae in the spinal column relative to one another. The vertebrae are preferably adjusted along both a sagittal plane and a coronal plane of a patient's body. In another non-fusion method for correcting spinal deformities, a spinal anchoring device is implanted in each of a plurality of vertebrae, and first and second flexible fixation elements are fixedly coupled to each spinal anchoring device such that segmental tension is applied between each anchoring device to adjust a position of each of the plurality of vertebrae in both a coronal plane and a sagittal plane of a patient's body. Each anchoring device can include an anchoring element that is adapted to mate to a vertebra, and a closure mechanism that is adapted to lock each of the first and second flexible fixation elements in a fixed position relative to the anchoring element.

20040528

20111011

20051215

96932.0

HOFFMAN, MARY C

NON-FUSION SPINAL CORRECTION SYSTEMS AND METHODS

UNDISCOUNTED

ACCEPTED

ACCEPTED

LIGHTING FIXTURE WITH NIGHT LIGHT

A lighting fixture has a night light that is always on, a safety light that provides more light than the night light, and a sensor that detects the presence of a person within the area illuminated by the safety light. The sensor turns on the safety light when a person is detected within said area and turns off the safety light after the person is no longer detected within the area. In that way, ample light is provided for safety and security purposes while dramatically reducing the amount of energy used.

1. A lighting fixture comprising (A) a night light that is always on; (B) a safety light that provides more light than said night light; and (C) a sensor that detects the presence of a person within the area illuminated by said safety light and turns on said safety light when a person is detected within said area and turns off said safety light after said person is no longer detected within said area: 2. A lighting fixture according to claim 1 wherein said night light provides at least 1 foot candle of light. 3. A lighting fixture according to claim 2 wherein said night light provides 1 to about 2 foot candles of light. 4. A lighting fixture according to claim 1 wherein said night light is a fluorescent bulb of about 3 to about 7 watts. 5. A lighting fixture according to claim 1 wherein said safety light provides about 8 to about 12 foot candles of light. 6. A lighting fixture according to claim 1 wherein said safety light is a single fluorescent bulb of about 20 to about 40 watts. 7. A lighting fixture according to claim 1 wherein said safety light is two fluorescent bulbs, each of about 10 to about 18 watts. 8. A lighting fixture according to claim 1 wherein said safety light provides about 3 to about 4 times as much light as said night light. 9. A lighting fixture according to claim 1 wherein said sensor detects the motion of a person. 10. A lighting fixture according to claim 1 wherein said sensor senses the difference between infrared energy from a person's body in motion and background space. 11. A lighting fixture according to claim 1 wherein said sensor turns off said safety light about 30 seconds to about 30 minutes after it no longer detects the presence of a person within said area. 12. A lighting fixture according to claim 1 that has an emergency ballast. 13. A lighting fixture according to claim 1 wherein said lens is a clear prismatic acrylic lens. 14. A corridor in a building having a lighting fixture according to claim 1 mounted therein. 15. A method of lighting a corridor in a building comprising mounting a lighting fixture according to claim 1 therein. 16. A stairwell in a building having a lighting fixture according to claim 1 mounted therein. 17. A method of lighting a stairwell in a building comprising mounting a lighting fixture according to claim 1 therein. 18. A lighting fixture comprising (A) a night light that is always on and provides about 1 to about 2 foot candles of light; (B) a safety light that comprises one or two bulbs that provide a total of about 8 to about 12 foot candles of light; and (C) a sensor that detects the presence of a person within the area illuminated by said safety light and turns on said safety light when a person is detected within said area and turns off said safety light about 30 seconds to about 30 minutes after said person is no longer detected within said area. 19. A lighting fixture according to claim 18 wherein said night light and said safety light are fluorescent lights. 20. A lighting fixture comprising (A) a fluorescent night light of about 3 to about 7 watts that is always on and provides about 1 to about 2 foot candles of light; (B) a fluorescent safety light that comprises one or two bulbs using a total power of about 20 to about 40 watts and providing about 8 to about 12 foot candles of light; and (C) a sensor that detects the presence of a person within the area illuminated by said safety light by sensing the difference between infrared energy from his body in motion and background space and turns on said safety light when a person is detected within said area and turns off said safety light about 1 to about 3 minutes after said person is no longer detected within said area.

BACKGROUND OF INVENTION This invention relates to an indoor lighting fixture equipped with a night light and a sensor. In particular, it relates to a lighting fixture that has a night light that is always on and a brighter safety light that comes on only when a sensor detects the presence of a person. Buildings and indoor parking garages are required by law to have lights in the corridors and stairwells, both for security and for safety. While the UCB (Uniform Code for Buildings) requires these lights to be only one foot candle, the conventional practice is to use much brighter lights in order to reduce or avoid liability for inadequate lighting. The cost of electricity for these lights in a large building can be a significant expense. SUMMARY OF INVENTION The lighting fixture of this invention conserves energy and reduces the cost of lighting corridors and stairwells in buildings such as office buildings, apartment buildings, hospitals, parking garages, and other facilities. The fixture has a night light that is continuously on, providing the minimum amount of light needed to comply with building regulations. The fixture also has a sensor that can detect the presence of a person. When a person is detected, a brighter safety light is turned on to provide ample light in the area. Once the person leaves, the safety light is turned off. Since the night light uses very little electricity and the safety light is usually on only very infrequently, the amount of electricity used for lighting corridors and stair-wells in buildings is cut dramatically. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an isometric view of a certain presently preferred embodiment of a lighting fixture according to this invention. FIG. 2 is a plan view of the lighting fixture of FIG. 1 with the lens removed. FIG. 3 is a circuit diagram of the lighting fixture according to this invention, where two bulbs are used for the safety light. FIG. 4 is an isometric view showing the lighting fixture of FIG. 1 mounted in a corridor. FIG. 5 is an isometric view showing the lighting fixture of FIG. 1 mounted in a stairwell. DETAILED DESCRIPTION In FIGS. 1 and 2, lighting fixture 1 has a casing 2 and a lens 3. Beneath lens 3 is a 32 watt fluorescent safety light 4, held by sockets 5, and a 5 watt compact fluorescent night light 6, held by socket 7. There is also a ballast 8 for for safety light 4 and a second ballast 9 for night light 6. At one end of fixture 1 is attached a sensor 10 that can detect the presence of a person in the area lit by safety light 4. In FIG. 3, a source of electrical power 11, typically 110 VAC or 220 VAC, supplies power continuously to night light 6. Sensor 10 is connected in series with two 15 watt fluorescent safety lights 12 and turns safety lights 12 on immediately when it detects a person and turns safety lights 12 off at a predetermined interval after the person is no longer detected. That interval can be set on sensor 10, by turning a knob (not shown) to the delay desired. The delay could be set, for example, to between about 30 seconds and about 30 minutes; a delay of about 1 to about 3 minutes is preferred. The night light of this invention preferably provides about 1 to about 2 foot candles, which meets the UCB requirement without wasting energy. A bulb of about 3 to about 7 watts is preferred for the night light and a 5 watt energy efficient fluorescent bulb is particularly preferred. Safety light 4 emits more light than night light 6, preferably about 3 to about 4 times as much light and preferably provides about 8 to about 12 foot candles. Safety light 4 may be a single bulb or several bulbs. The total power usage of safety light 4 for one or more bulbs may be, for example, about 20 to about 40 watts. If two bulbs are used, each may be about 10 to about 18 watts. Other types of lights besides fluorescent lights may also be used, such as incandescent lights, mercury vapor lights, and sodium vapor lights. Sensor 10 may detect the presence of a person in a variety of different ways, such as by the emission of infrared radiation (heat), by the breaking of a beam of light, by radar, etc. Preferably, it detects the presence of a person by motion. A preferred motion-detecting sensor detects the presence of a person by sensing the difference between infrared energy from a human body in motion and the background space; that sensor is available from The Watt Stopper, Inc. Preferred sensors can detect the presence of a person equally well in any direction (360°) within the space that is being lighted. Casing 2 is typically made of metal, but may be made of other materials, such as plastic, if desired. Lens 3 protects safety light 4 and night light 6 while transmitting as much light as possible. A variety of different types of lenses may be used; a clear prismatic acrylic lens is preferred. A locking lens system may be used to make it more difficult for vandals and criminals to break the lights. The lighting fixtures intended primarily for use indoors, but could also be used outdoors. They are typically mounted on the ceiling in a corridor, as shown in FIG. 4, or on the wall in a stairwell, as shown in FIG. 5. In a corridor (FIG. 4), a fixture 1 may be placed on the ceiling about every 16 feet and in a stairwell (FIG. 5) a fixture 1 may be mounted on the wall at every landing. An emergency ballast (i.e., a battery) may be added to the fixture to provide power during a power outage, if desired. This technology can also be used to retrofit existing fixtures, if applicable.

<SOH> BACKGROUND OF INVENTION <EOH>This invention relates to an indoor lighting fixture equipped with a night light and a sensor. In particular, it relates to a lighting fixture that has a night light that is always on and a brighter safety light that comes on only when a sensor detects the presence of a person. Buildings and indoor parking garages are required by law to have lights in the corridors and stairwells, both for security and for safety. While the UCB (Uniform Code for Buildings) requires these lights to be only one foot candle, the conventional practice is to use much brighter lights in order to reduce or avoid liability for inadequate lighting. The cost of electricity for these lights in a large building can be a significant expense.

<SOH> SUMMARY OF INVENTION <EOH>The lighting fixture of this invention conserves energy and reduces the cost of lighting corridors and stairwells in buildings such as office buildings, apartment buildings, hospitals, parking garages, and other facilities. The fixture has a night light that is continuously on, providing the minimum amount of light needed to comply with building regulations. The fixture also has a sensor that can detect the presence of a person. When a person is detected, a brighter safety light is turned on to provide ample light in the area. Once the person leaves, the safety light is turned off. Since the night light uses very little electricity and the safety light is usually on only very infrequently, the amount of electricity used for lighting corridors and stair-wells in buildings is cut dramatically.

20040530

20070123

20051201

66479.0

HUSAR, STEPHEN F

LIGHTING FIXTURE WITH NIGHT LIGHT

SMALL

ACCEPTED

ACCEPTED

ECHO CANCELLATION DEVICE FOR FULL DUPLEX COMMUNICATION SYSTEMS

An echo cancellation device for a full duplex communications system is provided. The full duplex communication system has a transmitter for transmitting a transmit signal and a receiver for receiving a receive signal. The echo cancellation device has a filter for outputting a filter signal according to the transmit signal, an echo cancellation circuit connected to the filter for outputting an echo cancellation signal according to the filter signal, at least one echo cancellation resistor connected to the transmitter, the receiver, and the echo cancellation circuit, and an echo cancellation detection circuit for outputting a control signal according to an echo residue at the receiver to control the filter.

1. An echo cancellation device for use in a full duplex communication system, wherein the full duplex communication system comprises a transmitter for transmitting a transmit signal and a receiver for receiving a receive signal, the echo cancellation device comprising: a filter for outputting a filtering signal according to the transmit signal; an echo cancellation circuit electrically coupled to the filter for outputting an echo cancellation signal according to the filtering signal; and at least an echo cancellation resistor electrically coupled to the transmitter, the receiver, and the echo cancellation circuit. 2. The echo cancellation device of claim 1, wherein the echo cancellation signal corresponds to the transmit signal. 3. The echo cancellation device of claim 1 further comprising a digital-to-analog converter. 4. The echo cancellation device of claim 1, wherein the filter further comprises a digital low pass filter. 5. The echo cancellation device of claim 1, wherein the filter further comprises an analog low pass filter. 6. The echo cancellation device of claim 1 further comprising an echo residue detection circuit for outputting a control signal to control at least a characteristic of the filter according to an echo residue received by the receiver. 7. The echo cancellation device of claim 6, wherein the filter is a finite impulse response (FIR) filter and the characteristic is at least a coefficient of the FIR filter. 8. The device of claim 6, wherein the filter is a infinite impulse response (IIR) filter and the characteristic is at least a coefficient of the IIR filter. 9. The echo cancellation device of claim 6, wherein the filter is a resistor-capacitor (RC) network low pass filter and the characteristic is the resistance of the resistor or the capacitance of the capacitor. 10. An echo cancellation device for use in a full duplex communication system, wherein the full duplex communication system comprises a transmitter for transmitting a transmit signal and a receiver for receiving a receive signal, the echo cancellation device comprising: a filter for outputting a filtering signal according to the transmit signal; an echo cancellation circuit electrically coupled to the filter for outputting an echo cancellation signal according to the filtering signal; at least an echo cancellation resistor electrically coupled to the transmitter, the receiver, and the echo cancellation circuit; and an echo residue detection circuit for outputting a control signal to adjust the filter according to an echo residue received by the receiver. 11. The echo cancellation device of claim 10, wherein the echo cancellation signal corresponds to the transmit signal. 12. The echo cancellation device of claim 10 further comprising a digital-to-analog converter. 13. The echo cancellation device of claim 10, wherein the filter further comprises a digital low pass filter. 14. The echo cancellation device of claim 13, wherein the digital low pass filter is a finite impulse response (FIR) filter and the FIR filter is adjusted through adjusting at least a coefficient of the FIR filter. 15. The echo cancellation device of claim 13, wherein the digital low pass filter is a infinite impulse response (IIR) filter and the IIR filter is adjusted through adjusting at least a coefficient of the IIR filter. 16. The echo cancellation device of claim 10, wherein the filter further comprises a RC network filter. 17. The echo cancellation device of claim 16, wherein the RC network filter further comprises a resistor. 18. The echo cancellation device of claim 17, wherein the resistor is implemented by a MOS transistor. 19. The echo cancellation device of claim 18, wherein the RC network filter is adjusted through adjusting a gate voltage applied to the gate electrode of the MOS transistor. 20. The echo cancellation device of claim 16, wherein the RC network filter comprises a capacitor. 21. The echo cancellation device of claim 20, wherein the capacitor comprises a parasitic capacitor. 22. The echo cancellation device of claim 20, wherein the RC network filter is adjusted through adjusting the capacitance of the capacitor.

BACKGROUND OF INVENTION 1. Field of the Invention The invention generally relates to a full duplex communication system, and more particularly, to an echo cancellation device for a full duplex communication system. 2. Description of the Prior Art As technology advances, network usage is more and more popular. The requirement of network bandwidth is increasing and the transmission speed of data packets of Ethernet has risen from 10/100 Mps to 1 Gbps. Please refer to FIG. 1, which is a block diagram of a 1 Gbps fast Ethernet system. In the 1 Gbps Ethernet system, each port has 4 channels 100 where each channel has a transceiver 102 and a line interface 116 electrically coupled to a twisted line 118. The transceiver 102 has a transmitter 104 and a receiver 106, wherein the transmitter 104 has a digital-to-analog converter (DAC) 108 to convert signals into analog form for transmitting to a far-end network device via the line interface 116 and the twisted line 118, and the receiver 106 has an analog front end (AFE) circuit for processing the received signal from the line interface 116 and an analog-to-digital converter (ADC) 114 for converting the processed signals into digital signals and then sending to the after circuits. The fast Ethernet and the far-end network device both simultaneously utilize the four channels where each channel simultaneously performs the transmitting and receiving operations. As a result, the fast Ethernet system is a full duplex communication system. Each channel of the fast Ethernet system simultaneously performs the transmitting and receiving operations. When the channel is transmitting, the signals received from the channel are affected by the transmission and this phenomenon is known as echo impairment. In order to reduce echo impairment, an echo cancellation device 110 and an echo cancellation resistor Rp are usually disposed in the transmitter 104 as illustrated in FIG. 1. The echo cancellation device 100 is usually a digital-to-analog converter (DAC) to output a cancellation signal that is similar to the output signal from the DAC 108 so the cancellation signal can cancel the adverse effects on the receiver 106 by the transmitted signals to achieve echo cancellation. Please refer to FIG. 2, which is an equivalent circuit of the fast Ethernet device in FIG. 1. The circuit equivalence of the DAC 108 and the echo cancellation device 110 of the transmitter 104 are current sources Id and Ic respectively. For the receiver 106 to achieve echo cancellation, the output of the current sources Ic and Id must cancel the adverse effects caused by the transmitter 106. Please refer to FIG. 3, which is a model of the equivalent circuit in FIG. 2. Zo is the effective output impedance which in FIG. 2 includes a matching resistor Rm for matching impedance and an effective resistor Rc of the channel. Vo is the output signal which is the transmitted signal from the transmitter 104 and is also the received signal from the receiver 106. From the circuit in FIG. 3, we can draw the following formula: Vi = - Zi ⁡ [ IdZo + ( Zo + Rp ) ⁢ Ic ] Rp + Zi + Zo ( 1 ) in order to cancel echo, set vi=0, which satisfies: IdZo+(Zo+Rp)Ic=0 (2) therefore the relationship between Ic and Id is: Ic = - Zo Rp + Zo ⁢ Id ( 3 ) to accomplish echo cancellation. The disadvantages of conventional echo cancellation device is that the effective output impedance Zo is seen as a pure load resistor Re, where the resistance characteristics are based on the matching resistor Rm and the effective resistor Rc. Besides the matching resistor Rm and the effective resistor Rc of the channel, the effective output impedance is also affected by the parasitic capacitance Ce that is unavoidable during operation of the circuit. If the effective output impedance is seen purely as a load resistor Re, echo cancellation cannot be effectively reduced to the lowest. SUMMARY OF INVENTION It is therefore one of the objects of the claimed invention to provide an echo cancellation device for a full duplex communication system that can effectively cancel echo impairment to solve the above-mentioned problem. According to the claimed invention, an echo cancellation device for a full duplex communication system is provided. The full duplex communication system comprises a transmitter for transmitting a transmit signal and a receiver for receiving a receive signal. The echo cancellation device comprises: a filter for filtering the transmit signal; at least an echo cancellation resistor electrically coupled to the transmitter, the receiver, and the echo cancellation device; and an echo residue detection circuit for generating a control signal to control the filter according to the echo residue. These and other objectives of the claimed invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. BRIEF DESCRIPTION OF DRAWINGS FIG.1 is a block diagram of a 1 Gbps fast Ethernet device according to the embodiment of the present invention. FIG. 2 is an equivalent circuit of the fast Ethernet device in FIG. 1. FIG. 3 is a small signal model for the equivalent circuit in FIG. 2. FIG. 4 is a block diagram of the fast Ethernet device according to the embodiment of the present invention. FIG. 5 is a schematic diagram of the digitally implemented low pass filter in FIG. 4. FIG. 6 is a schematic diagram of the analogly implemented low pass filter in FIG. 4. FIG. 7 is a block diagram of the fast Ethernet device according to another embodiment of the present invention. DETAILED DESCRIPTION Please refer to FIG. 3, the present invention takes into consideration the unavoidable parasitic capacitance in a practical circuit. The effective output impedance Zo is the parallel of the parasitic capacitance Ce and the load resistor Re, which is made up of the matching resistor Rm and the channel effective resistor Rc. The effective output impedance Zo is calculated by the following equation: Zo = Re sReCe + 1 ( 4 ) substitute formula (4) into formula (3) to obtain formula (5): Ic = - Re Rp + Re + sReRpCe ⁢ Id = H ⁡ ( s ) · Id ( 5 ) From formula (5), it is known that the relationship between Ic and Ic is defined by a low pass transfer function. Please refer to FIG. 4, which shows a block diagram of the fast Ethernet device according to the first embodiment of the present invention. The echo cancellation device of the embodiment of the present invention comprises: an echo cancellation circuit 410 for generating a cancellation signal that corresponds to the transmit signal from the DAC 408; an echo cancellation resistor Rp electrically coupled between the transmitter 404 and the receiver 406; and a low pass filter 420 electrically coupled to the echo cancellation circuit 410 as a front-end circuit. The echo cancellation circuit 410 can be a DAC and the low pass filter 420 can be implemented either analogly or digitally. The digital low pass filter 420 is shown in FIG. 5 and the analog low pass filter 420 is the RC network low pass filter which is shown in FIG. 6. The low pass filter 420 allows the cancellation signal outputted by the echo cancellation circuit 410 to cancel the transmit signal from the DAC 408 (the current source Id in the circuit) so echo impairment of the receiver 406 is reduced to a minimum. The capacitor in FIG. 6 can be a metal-stacked layer capacitor or a parasitic capacitor and the resistor can be a MOS transistor where the equivalent resistance of the MOS transistor is controlled by the Vd of the gate electrode. Please refer to FIG. 7, which is a block diagram of the fast Ethernet device according to a second embodiment of the present invention. In practical operation, the capacitance of the parasitic capacitor Ce, the channel effective resistor Rc, and the impedance matching resistor Rm are affected by the operating environment, temperature, manufacturing deviations, and the like, therefore the values will fluctuate and change when transmitting/receiving data. In order to more precisely eliminate echo, in the second embodiment of the present invention, the receiver 706 further comprises an echo residue detection circuit 722 for detecting the amount of echo residue at the receiver 706. The echo residue detection circuit 722 outputs a control signal to the low pass filter 720 according to the detected echo residue to form a loop. The digitally implemented low pass filter 720 takes the adjustment of the coefficients of a finite impulse response (FIR) or a infinite impulse response (IIR) and the analogly implemented low pass filter 720 takes the adjustment of the RC value of the low pass RC filter by controlling the gate voltage Vd to actively adjust the low pass filter 720 according to the different characteristics of circuit components and network environment to maintain the best echo cancellation performance. Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teachings of the invention. Accordingly, that above disclosure should be construed as limited only by the metes and bounds of the appended claims.

<SOH> BACKGROUND OF INVENTION <EOH>1. Field of the Invention The invention generally relates to a full duplex communication system, and more particularly, to an echo cancellation device for a full duplex communication system. 2. Description of the Prior Art As technology advances, network usage is more and more popular. The requirement of network bandwidth is increasing and the transmission speed of data packets of Ethernet has risen from 10/100 Mps to 1 Gbps. Please refer to FIG. 1 , which is a block diagram of a 1 Gbps fast Ethernet system. In the 1 Gbps Ethernet system, each port has 4 channels 100 where each channel has a transceiver 102 and a line interface 116 electrically coupled to a twisted line 118 . The transceiver 102 has a transmitter 104 and a receiver 106 , wherein the transmitter 104 has a digital-to-analog converter (DAC) 108 to convert signals into analog form for transmitting to a far-end network device via the line interface 116 and the twisted line 118 , and the receiver 106 has an analog front end (AFE) circuit for processing the received signal from the line interface 116 and an analog-to-digital converter (ADC) 114 for converting the processed signals into digital signals and then sending to the after circuits. The fast Ethernet and the far-end network device both simultaneously utilize the four channels where each channel simultaneously performs the transmitting and receiving operations. As a result, the fast Ethernet system is a full duplex communication system. Each channel of the fast Ethernet system simultaneously performs the transmitting and receiving operations. When the channel is transmitting, the signals received from the channel are affected by the transmission and this phenomenon is known as echo impairment. In order to reduce echo impairment, an echo cancellation device 110 and an echo cancellation resistor Rp are usually disposed in the transmitter 104 as illustrated in FIG. 1 . The echo cancellation device 100 is usually a digital-to-analog converter (DAC) to output a cancellation signal that is similar to the output signal from the DAC 108 so the cancellation signal can cancel the adverse effects on the receiver 106 by the transmitted signals to achieve echo cancellation. Please refer to FIG. 2 , which is an equivalent circuit of the fast Ethernet device in FIG. 1 . The circuit equivalence of the DAC 108 and the echo cancellation device 110 of the transmitter 104 are current sources Id and Ic respectively. For the receiver 106 to achieve echo cancellation, the output of the current sources Ic and Id must cancel the adverse effects caused by the transmitter 106 . Please refer to FIG. 3 , which is a model of the equivalent circuit in FIG. 2 . Zo is the effective output impedance which in FIG. 2 includes a matching resistor Rm for matching impedance and an effective resistor Rc of the channel. Vo is the output signal which is the transmitted signal from the transmitter 104 and is also the received signal from the receiver 106 . From the circuit in FIG. 3 , we can draw the following formula: Vi = - Zi ⁡ [ IdZo + ( Zo + Rp ) ⁢ Ic ] Rp + Zi + Zo ( 1 ) in order to cancel echo, set vi=0, which satisfies: in-line-formulae description="In-line Formulae" end="lead"? IdZo +( Zo+Rp ) Ic= 0   (2) in-line-formulae description="In-line Formulae" end="tail"? therefore the relationship between Ic and Id is: Ic = - Zo Rp + Zo ⁢ Id ( 3 ) to accomplish echo cancellation. The disadvantages of conventional echo cancellation device is that the effective output impedance Zo is seen as a pure load resistor Re, where the resistance characteristics are based on the matching resistor Rm and the effective resistor Rc. Besides the matching resistor Rm and the effective resistor Rc of the channel, the effective output impedance is also affected by the parasitic capacitance Ce that is unavoidable during operation of the circuit. If the effective output impedance is seen purely as a load resistor Re, echo cancellation cannot be effectively reduced to the lowest.

<SOH> SUMMARY OF INVENTION <EOH>It is therefore one of the objects of the claimed invention to provide an echo cancellation device for a full duplex communication system that can effectively cancel echo impairment to solve the above-mentioned problem. According to the claimed invention, an echo cancellation device for a full duplex communication system is provided. The full duplex communication system comprises a transmitter for transmitting a transmit signal and a receiver for receiving a receive signal. The echo cancellation device comprises: a filter for filtering the transmit signal; at least an echo cancellation resistor electrically coupled to the transmitter, the receiver, and the echo cancellation device; and an echo residue detection circuit for generating a control signal to control the filter according to the echo residue. These and other objectives of the claimed invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

20040607

20071204

20050512

63651.0

SINGH, RAMNANDAN P

ECHO CANCELLATION DEVICE FOR FULL DUPLEX COMMUNICATION SYSTEMS

UNDISCOUNTED

ACCEPTED

ACCEPTED

STRUCTURE AND METHOD OF PATTERNING A MAGNETIC TUNNEL JUNCTION STACK FOR A MAGNETO-RESISTIVE RANDOM ACCESS MEMORY

A method of patterning a magnetic tunnel junction (MTJ) stack is provided. According to such method, an MTJ stack is formed having a free layer, a pinned layer and a tunnel barrier layer disposed between the free layer and the pinned layer. A first area of the MTJ stack is masked while the free layer of the MTJ is exposed in a second area. The free layer is then rendered electrically and magnetically inactive in the second area.

1. A method of patterning a magnetic tunnel junction (MTJ) stack comprising; forming an MTJ stack having a free layer, a pinned layer and a tunnel barrier layer disposed between said free layer and said pinned layer; masking a first area of said MTJ stack while exposing said free layer of said MTJ stack in a second area; rendering said free layer electrically and magnetically inactive in said second area. 2. A method as claimed in claim 1, wherein said stack is formed over one or more interlevel dielectric layers in which one or more respective metal conductor layers are disposed. 3. A method as claimed in claim 1, wherein said free layer is rendered electrically and magnetically inactive through conversion to an inert compound by chemically altering its composition. 4. A method as claimed in claim 3, wherein said free layer is chemically altered by plasma treatment. 5. The method of claim 4, wherein said plasma treatment includes plasma oxidation. 6. The method of claim 5, wherein said plasma oxidation is performed at an elevated temperature that is higher than room temperature. 7. The method of claim 5, wherein said plasma oxidation is performed at a reduced temperature that is lower than room temperature. 8. The method of claim 5, wherein said chemical alteration further includes acceleration of oxygen ions. 9. The method of claim 3, wherein said free layer is chemically altered by exposure to a chemical agent including at least one agent selected from the group consisting of fluorine, carbon, and nitrogen. 10. A method as claimed in claim 1, wherein said free layer is rendered electrically and magnetically inactive through oxidation. 11. The method of claim 3, wherein said free layer is chemically altered by anodization. 12. The method of claim 1, wherein said free layer is rendered electrically and magnetically inactive by physically altering its composition. 13. The method of claim 12, wherein said free layer is rendered electrically and magnetically inactive by adding additional atoms to said free layer. 14. The method of claim 12, wherein the additional atoms are added by ion implantation. 15. The method of claim 1, wherein said free layer includes a layer consisting essentially of nickel-iron (NiFe). 16. The method of claim 12, wherein the additional atoms are added by diffusion out of an adjacent “donor” film into said free layer of at least one agent selected from the group consisting of oxygen, nitrogen, fluorine, and carbon. 17. The method of claim 1, wherein said masking is conducted by forming a hardmask including at least one material selected from the group consisting of titanium nitride (TiN), tantalum nitride (TaN), and a sacrificial material, wherein said free layer includes iron, and said tunnel barrier layer includes at least one material selected from the group consisting of aluminum oxide and magnesium oxide. 18. A method of patterning an MTJ stack of a magneto-resistive random access memory (MRAM) comprising; forming an interlevel dielectric layer (ILD) over a substrate, said ILD including a plurality of conductive lines and vias; forming an MTJ stack overlying said ILD, said MTJ stack including a pinned layer, a tunnel barrier layer overlying said pinned layer, and a free layer overlying said tunnel barrier layer; masking a portion of said MTJ stack to expose an area of said free layer; and converting said exposed area of said free layer to a non-magnetic compound by altering its composition. 19. The method of claim 18, wherein said exposed area is also rendered highly resistive. 20. A structure including a magnetic tunnel junction (MTJ), comprising: an MTJ stack including a first portion of a pinned layer, a first portion of a tunnel barrier layer overlying said first portion of said pinned layer, and a free layer overlying said first portion of said tunnel barrier layer; and a layered stack abutting one or more peripheral edges of said MTJ stack, said layered stack including a second portion of said pinned layer, a second portion of said tunnel barrier layer, and an electrically and magnetically inactive compound of a material included in said free layer.

BACKGROUND OF INVENTION The invention relates to microelectronic devices, and more particularly to a magnetic tunnel junction and method for patterning the same. In a magneto-resistive random access memory (MRAM), information is stored in arrays of magnetic storage elements known as magnetic tunnel junctions (MTJs). One of the advantages of MRAM is the capability of the MTJ storage array to be placed in a level above the surface of a semiconductor substrate. In that way, the surface area of the semiconductor substrate is conserved for use by relatively few transistors used to control the MTJ array. In addition, the available substrate surface area does not constrain the density of the MRAM to the same extent as in other types of memory. MRAM technology potentially offers great benefits to the integration of processors and other system elements on a single integrated circuit (IC or “chip”), commonly referred to as “systems on a chip” (SOCs). The placement of the MTJ array in a layer above the semiconductor substrate surface increases the flexibility for fabricating the MRAM cell control transistors in the substrate. With such flexibility, MRAM cell control transistors can be fabricated using most, if not all of the same process steps as transistors used in logic circuitry, e.g. a microprocessor, of such chip. Another advantage of MRAM compared to dynamic random access memory (DRAM) and static random access memory (SRAM), is that the stored information is non-volatile. In an MRAM, information is stored according to the orientation of magnetic dipoles within an MTJ storage element of each MRAM cell. The magnetic dipoles are re-orientable by application of a magnetic field to program the MTJ, that is, to write information to the MTJ. Once the MTJ is programmed by the magnetic field, the MTJ remains in either a first state or a second state until reprogrammed by a different magnetic field, even if power is removed from the MTJ in the meantime. An advantage of MRAM compared to other non-volatile rewriteable memory such as flash memory, is that the MTJ has longer life. Current technology suggests that MTJs are reprogrammable many billions of cycles. Flash memory, which utilizes thin dielectrics and is reprogrammed by applying relatively high voltage (10 V to 15 V) and current, typically fails within one million cycles. A magnetic tunnel junction memory element includes a structure having ferromagnetic layers separated by a non-magnetic tunnel barrier. Digital information is stored and represented in the memory element as directions of magnetization vectors in the ferromagnetic layers. More specifically, the magnetic moment of one magnetic layer is fixed. Such layer is called the “pinned” or “reference” layer. The magnetic moment of the other magnetic layer may be switched to be either parallel or antiparallel to the pinned layer. This layer is called the “free” or “soft” layer. When the orientations in the pinned layer and the free layer are parallel, the MTJ is in a first state having a first electrical resistance. On the other hand, when the orientations in the pinned layer and the free layer are antiparallel, the MTJ is in a second state, in which its electrical resistance is significantly higher than in the first state. In general, the device state is determined by the orientation of the magnetic films in closest proximity to the tunnel barrier, even if the pinned and free layers are themselves comprised of multiple layers of materials. Such composite pinned and free layers are common, as they can enhance device operation and lifetime. The patterning of the MTJ device is one of the most challenging aspects of fabrication. Conventional techniques used to pattern other structures of a chip, such as reactive ion etching (RIE) or ion milling, have been less than satisfactory when applied to the materials that compose magnetic stacks. In most cases utilizing such techniques, it is extremely difficult to cleanly remove etched material. Physical sputtering, often the dominant component of magnetic material RIE, usually results in the formation of re-deposited residues (called “fences” or “veils”) that can short circuit the junctions of the MTJ, as well as short circuit conductive patterns in different metal layers. Short circuiting may occur either immediately as a result of such fence residues, or after subsequent high temperature processing. Another problem of conventional etch techniques is corrosion and degradation of the patterned free and pinned layers that form the MTJ, due to chemical residue remaining after etching. Exposure to reactive gases during deposition of dielectrics such as silicon nitride and silicon dioxide after the etching of the MTJ can also cause corrosion and degradation. For example, fluorine and/or chlorine species may be present when plasma-etching a stack of magnetic films. Chlorine and fluorine species can combine with conductive and photoresist material removed in the process to deposit a conductive residue along sidewalls of the stack. When subjected to high temperatures, the residue can migrate and cause corrosion, degradation and electrical shorting. One way proposed for handling these problems is development of a process having better selective etch control to minimize exposure of sensitive interfaces to corrosive chemicals and conductive fences. Such etch process should have high selectivity, in order for etching to stop when the thin tunnel barrier layer of a magnetic film stack is reached. Such etch process is known as stop on alumina (SOA), named historically because many of the MTJ tunnel barriers are formed from alumina-type compounds. However, the tight process control and high selectivity required to maintain an acceptably controlled etch process across an entire wafer is difficult to achieve. Moreover, the SOA process does not necessarily protect the free layer from harmful corrosion and degradation. Accordingly, it is desirable to provide an improved structure and method for patterning magnetic tunnel junctions of an MRAM. SUMMARY OF INVENTION According to an aspect of the invention, a method of patterning a magnetic tunnel junction (MTJ) stack is provided. According to such method, an MTJ stack is formed having a free layer, a pinned layer and a tunnel barrier layer disposed between the free layer and the pinned layer. A first area of the MTJ stack is masked while the free layer of the MTJ is exposed in a second area. The free layer is then rendered electrically and magnetically inactive in the second area. According to another aspect of the invention, a method is provided for patterning an MTJ stack of a magneto-resistive random access memory (MRAM). Such method includes forming an interlevel dielectric layer (ILD) over a substrate, the ILD including a plurality of conductive lines and vias. An MTJ stack is then formed overlying the ILD, the MTJ stack including a pinned layer, a tunnel barrier layer overlying the pinned layer, and a free layer overlying the tunnel barrier layer. A portion of the MTJ stack is masked to expose an area of the free layer. The exposed area is then converted to a non-magnetic compound by altering its composition. According to yet another aspect of the invention, a structure including a magnetic tunnel junction (MTJ) is provided. Such structure includes an MTJ stack having a first portion of a pinned layer, a first portion of a tunnel barrier layer overlying the first portion of the pinned layer, and a free layer overlying the first portion of the tunnel barrier layer. The structure further includes a layered stack abutting one or more peripheral edges of the MTJ stack, the layered stack including a second portion of the pinned layer, a second portion of the tunnel barrier layer, and an electrically and magnetically inactive compound of a material included in the free layer. BRIEF DESCRIPTION OF DRAWINGS FIGS. 1 through 4 are cross sectional views illustrating stages in the fabrication of a magnetic tunnel junction (MTJ) according to an embodiment of the invention. FIG. 5 is a graph illustrating the Kerr signal returned from a ferromagnetic material layer, after processing the layer with oxygen ions at selected acceleration voltages. DETAILED DESCRIPTION FIG. 1 is a cross-sectional view illustrating the structure of a patterned MTJ storage element 100 and its interconnection to M1 and M2 conductive lines. The MTJ 100 includes a pinned layer 132, a tunnel barrier layer 134 and a free layer 136. Each of these layers 132, 134, and 136 can include one or several layers which work together to enhance device performance or manufacturability. The free layer 136 is adjoined at first edges 135 of the MTJ by portions 143 of the free layer material that has been purposely inactivated. Preferably, the free layer 136 is also adjoined by the same type of inactivated material at second edges (not shown) in front of and in back of the MTJ 100, (the second edges not being visible in the particular cross-section shown), such that the MTJ 100 is surrounded by the same type of purposely inactivated material. The portions 143 of inactivated material extend to outer edges 156 of the patterned structure beyond the MTJ 100. The pinned layer 132 and tunnel barrier layer 134 also extend in a substantially horizontal direction to areas beyond the first edges 135 and second edges of the MTJ 100 to the outer edges 156. The MTJ 100 is disposed at the crossing of M1 and M2 conductive lines 102, 104. The M1 conductive lines 102 are parts of a first metallization layer that includes a first interlevel dielectric layer (ILD) 110 for electrically isolating the M1 lines from each other. The M2 conductive line 104 is part of a second metallization layer, which includes a second interlevel dielectric layer (ILD) 120 that electrically isolates respective M2 lines from each other. A conductive via 122 is disposed in an interlevel dielectric layer VA ILD 124 lying between the first and second ILDs 110 and 120, the conductive via 122 interconnecting an M1 line 102 to the pinned layer 132 of the MTJ 100. Conductive interconnection between the MTJ 100 and the M2 conductive line 104 is provided by a conductive member 160 which may also serve as a hard mask during processing. Referring to FIG. 2, a method of fabricating an MTJ according to a preferred embodiment of the invention will now be described. As shown in FIG. 2, a layered stack 140 is provided including the pinned layer 132, a tunnel barrier layer 134, and a free layer 136. The pinned layer 132 typically includes the following layers listed in order, from the bottom up: an adhesion layer, typically including 5 to 10 nm of TaN and/or Ta, a relatively thick antiferromagnet, illustratively including a 20 nm thick layer of PtMn or IrMn, and then a ferromagnetic “reference” layer or set of layers formed overlying and pinned by the antiferromagnet. The ferromagnetic reference layer is comprised of films such as CoFe and NiFe, which may be interspersed with a nonmagnetic coupling layer such as Ru or TaN that is used to reduce offsets from demagnetization fields. A representative thickness of the ferromagnetic reference layer(s) is 2 to 5 nm. The purpose of the antiferromagnet is to fix the ferromagnetic reference layer(s) such that they will not switch magnetization direction during normal operation, thus providing a reference against which to compare the free layer magnetization direction (which will be switched). The foregoing layers make up the pinned layer of the MTJ. The tunnel barrier layer 134 is formed by deposition of a thin dielectric layer onto the pinned layer 132. Typically, the tunnel barrier layer 134 is formed of an oxide of aluminum, such as including or similar to Al2O3, having a thickness of about 1 nm. Other materials available for use as the tunnel barrier layer 134 include oxides of magnesium, oxides of silicon, nitrides of silicon, and carbides of silicon; oxides, nitrides and carbides of other elements, or combinations of elements and other materials including or formed from semiconducting materials. The free layer 136 is formed by depositing onto the tunnel barrier layer 134 a layer of nickel-iron (NiFe) having a thickness of about 5 nm. Thereafter, a conductive barrier layer of tantalum nitride (TaN) having a thickness of about 5 nm is formed by deposition. This TaN layer serves to protect the NiFe layer during subsequent processing and to provide adhesion for one or more subsequently formed layers. Alternatively, NiCoFe, amorphous CoFeB, and similar ferromagnets can be used in place of NiFe as the ferromagnetic portion of the free layer. In an alternative embodiment, the free layer can be formed of more than one such ferromagnetic layer to enhance performance or manufacturability. Multiple layers may be separated by non-magnetic layers like TaN or Ru. These layers typically range in thickness from 2 to 10 nm. As further shown in FIG. 2, a layer 150 of hard mask material is formed on the layered stack 140. In the simplest embodiment, the hard mask 150 is formed from a conductive material such as tantalum nitride (TaN) or titanium nitride (TiN). Alternatively, the hardmask is formed from a sacrificial material and can be a dielectric or a conductor. In such case, after patterning the MTJ, the sacrificial material is removed and replaced by a conductor to connect the M2 wire (FIG. 1) with the free layer of the MTJ. The connecting conductor and M2 metallization can be formed by standard copper Damascene techniques. Thereafter, as illustrated in FIG. 3, the hard mask layer 150 is patterned (typically, together with the foregoing described layer of TaN) to selectively expose portions 142 of the free layer. The exposed portions 142 of the free layer are then converted to electrically and magnetically inactive material by chemically and/or physically altering the material composition. A variety of processes can be utilized to effect such alteration. Referring to FIG. 4, such processing results in the formation of portions 143 of inactivated material where the free layer is not protected by the hard mask 150. Such portions 143 are made magnetically inactive, such that no net moment is present. The portions 143 are also made highly resistive, such that their effects as a shunt path around the tunnel barrier 134 can be ignored. As illustrated in FIG. 4, some volumetric expansion typically occurs when the material of the free layer in portions 143 is inactivated as a result of oxidation or other similar conversion. The oxidation process must be conducted in a manner so that any such volumetric expansion does not cause excessive stress or delamination of one or more layers of the structure. In addition, the processing method used to inactivate the material in portions 143 should prevent the inactivated material from being converted back into a conductive and/or magnetic phase by subsequent processing. Moreover, the condition of the tunnel barrier layer 134, as well as the portion 144 of the free layer protected by the hard mask 150, should not be degraded by such subsequent processing, e.g., subsequent high temperature processing. As will now be described, several methods are available to effect the conversion of the exposed portions of the free layer, although the invention is not limited to any particular method. A first method for altering the free layer material involves oxidation by exposure to a plasma. In this first method, a plasma which contains oxygen ions is applied to the exposed portions of the free layer. Plasma oxidation can be performed with or without accelerating oxygen ions in a direction normal to the surface of the exposed portions to implant the oxygen ions therein. When such plasma implantation is used, any undercut of the portion of the tunnel barrier layer 134 and of the free layer beneath the hardmask 150 can be made slight, particularly when the process is performed at or below room temperature. The plasma oxidation can be performed whether or not accompanied by directional acceleration for implantation, and whether or not performed at a reduced temperature. For more rapid and more thorough conversion of the magnetic material, plasma oxidation can also be performed at elevated temperatures, as high as the integrity of the tunnel junction will allow (approximately 300-400° C.). Another conversion technique involves exposure to fluorine and/or nitrogen agents. Other available techniques include ion implantation that is not performed in presence of a plasma. Anodization is another suitable technique wherein wet electrochemistry provides a source of additional atoms to chemically alter the exposed portions 142 of the free layer. Lastly, combinations of any of the above methods can be used with increased effectiveness. Patterning of the MTJ by conversion of exposed portions 142 of the free layer offers the following advantages. Referring to FIG. 1, edges including first edges 135 and second edges (not shown) of the MTJ structure are prevented from being exposed to ambients during processing. This reduces the risk of corrosion and resulting degradation of the MTJ. A large process window is achieved for sufficiently or completely oxidizing the material of the free layer in portions 143, while stopping on the tunnel barrier 134 to leave the pinned layer 132 substantially unaffected. Oxidation that stops on the tunnel barrier 134 reduces offset fields from demagnetization contributions from the pinned layer 132. For example, a standard etch process will likely penetrate part-way into the pinned layer, leaving an unpredictable magnetic field emanating from the edge of the pinned layer. When the pinned layer of an MTJ makes a demagnetization contribution, a resultant unbalanced magnetic coupling can cause a shift in the hysteresis loop for the MTJ, reducing the operating window. By eliminating the demagnetization contribution and reducing the loop offset, more uniform behavior among MTJ elements can be achieved across a chip and across the entire wafer. While it is in principle possible to use etch techniques to stop on the tunnel barrier 134, in practice, this is quite difficult, and the conversion techniques outlined in this invention provide a much larger process window to allow effective stopping on the tunnel barrier 134. With continued reference to FIG. 1, after free layer conversion, the converted regions 143, the tunnel barrier layer 134 and the pinned layer 132 are now patterned at edges 156 to electrically isolate MTJs from each other. This is preferably performed in the following manner. With the patterned TiN hardmask material 150 (FIG. 4) still in place, a dielectric layer 152, e.g. of silicon dioxide or silicon nitride, is deposited over the structure in turn, followed by deposition and patterning of a photoresist material. The dielectric layer 152 is then patterned, followed by stripping the photoresist, and the dielectric layer 152 becomes a hardmask for reactive ion etching (RIE) the layers 143, 134, and 132 selectively to the underlying material of VA ILD 124. The dielectric material 152 tends to become eroded near the outer edges 156 of the patterned structure, accounting for their sloped appearance. Thereafter, the M2 ILD 120 is deposited over the patterned structure, and then polished flat and patterned to form a trough-shaped opening that exposes the hard mask material 150 (FIG. 4). When the hardmask material 150 is a conductive material such as TiN, the hard mask material is left in place as the conductive member 160 shown in FIG. 1. In such case, the M2 conductive line 104 is deposited in the opening in contact with the hardmask material to complete the structure shown in FIG. 1. In such structure, the previously deposited TiN material 150 is now used to conductively interconnect the M2 conductive line 104 to the MTJ 100. When the hardmask material 150 is a sacrificial material such as a dielectric, the sacrificial material is removed from the opening to expose the TaN cover portion of the free layer 136. For example, oxygen ashing would be used to remove a SiLK dielectric mandrel. A conductive member 160 is then formed in place of the prior hardmask, as by the same metallization process used to form the M2 metallization layer including M2 conductive line 104. FIG. 5 provides data to show conclusively that a NiFe magnetic free layer is converted to an essentially magnetically neutral layer by oxidation when conditions sufficiently oxidize the free layer. The data points graphed in FIG. 5 are expressed in Kerr signal vs. acceleration voltage for oxygen ions. When light is reflected from the surface of a magnetized layer, i.e. one having a substantial proportion of the dipoles contained in the layer oriented in one direction, a change is observed in the polarization of the light. The measured change in polarization is a Kerr signal. The more strongly the layer is magnetized, the stronger the Kerr signal becomes. FIG. 5 illustrates that when the magnetic free layer is more completely oxidized by driving oxygen ions into the free layer at higher acceleration voltage, the Kerr signal drops, and eventually reaches zero. This demonstrates the effectiveness of the technique in making the free layer become magnetically neutral. A corresponding increase in film sheet resistance has been observed with increasing oxidation of the NiFe layer. Experiments have shown that when the Kerr signal eventually decreases to zero, the resistance of the NiFe layer becomes extremely large, such that the oxidized free layer does not shunt an appreciable amount of current away from the active MTJ. These experiments demonstrate that the material of the free layer such as NiFe can be converted to a magnetically and electrically inactive form by oxidation. According to a preferred embodiment of the invention, oxidation by ion implantation is performed using Ar and O2 in an atomic ratio of 10 to 1. Post implantation annealing is performed at a temperature ranging between about 150 to 500 degrees C., preferably between about 250 to 350 degrees C., and most preferably between 250 and 300 degrees C. Experiments have shown that such annealing does not magnetically reactivate the oxidized NiFe. According to preferred embodiments of the invention, the addition of cobalt to the alloy used as the free layer enhances the propensity of such layer to be oxidized. Cobalt-containing materials such as NiCoFe and CoFeB are among such materials available for use as the free layer material. The presence of boron in amorphous alloys such as the CoFeB leads to formation of a glassy oxidized phase having good dielectric properties. Referring to FIG. 1, one result of the process according an embodiment of the invention is that the edges 135 of the MTJ 100 including first edges 135 and second edges (not shown) are protected from exposure to an ambient during processing. As described in the background, the conventional process leaves the edges of the MTJ exposed to an ambient during processing, which can result in corrosion or degradation during subsequent processing. Other advantages of the MTJ according to embodiments of the invention include protecting the underlying layer (i.e., the pinned layer) from being affected by processes such as oxidation or partial etching. The fabrication of MTJ structures including moisture-sensitive tunnel barriers or which use amorphous alloys as the free layer is aided by the embodiments of the invention because of the reduced exposure to ambients. The MTJ stack may include a tunnel barrier layer having a material that is moisture sensitive, such as MgO. In such case, patterning of the MTJ by oxidation rather than by etching protects the tunnel barrier layer from exposure to ambients. Protecting such tunnel barrier layer can be essential to providing an MTJ having good switching characteristics. Finally, processes according to foregoing described embodiments of the invention are implemented using readily available and simple techniques. For that reason, they are cost-effective to implement. In addition, processes according to the foregoing described embodiments are easily integrated into fabrication processes for MRAMs that include storage cells having field effect transistors (FETs) to control the MTJs, as well as MRAMs without such transistors (in the so-called crosspoint architecture). While the invention has been described in accordance with certain preferred embodiments thereof, those skilled in the art will understand the many modifications and enhancements which can be made thereto without departing from the true scope and spirit of the invention, which is limited only by the claims appended below.

<SOH> BACKGROUND OF INVENTION <EOH>The invention relates to microelectronic devices, and more particularly to a magnetic tunnel junction and method for patterning the same. In a magneto-resistive random access memory (MRAM), information is stored in arrays of magnetic storage elements known as magnetic tunnel junctions (MTJs). One of the advantages of MRAM is the capability of the MTJ storage array to be placed in a level above the surface of a semiconductor substrate. In that way, the surface area of the semiconductor substrate is conserved for use by relatively few transistors used to control the MTJ array. In addition, the available substrate surface area does not constrain the density of the MRAM to the same extent as in other types of memory. MRAM technology potentially offers great benefits to the integration of processors and other system elements on a single integrated circuit (IC or “chip”), commonly referred to as “systems on a chip” (SOCs). The placement of the MTJ array in a layer above the semiconductor substrate surface increases the flexibility for fabricating the MRAM cell control transistors in the substrate. With such flexibility, MRAM cell control transistors can be fabricated using most, if not all of the same process steps as transistors used in logic circuitry, e.g. a microprocessor, of such chip. Another advantage of MRAM compared to dynamic random access memory (DRAM) and static random access memory (SRAM), is that the stored information is non-volatile. In an MRAM, information is stored according to the orientation of magnetic dipoles within an MTJ storage element of each MRAM cell. The magnetic dipoles are re-orientable by application of a magnetic field to program the MTJ, that is, to write information to the MTJ. Once the MTJ is programmed by the magnetic field, the MTJ remains in either a first state or a second state until reprogrammed by a different magnetic field, even if power is removed from the MTJ in the meantime. An advantage of MRAM compared to other non-volatile rewriteable memory such as flash memory, is that the MTJ has longer life. Current technology suggests that MTJs are reprogrammable many billions of cycles. Flash memory, which utilizes thin dielectrics and is reprogrammed by applying relatively high voltage (10 V to 15 V) and current, typically fails within one million cycles. A magnetic tunnel junction memory element includes a structure having ferromagnetic layers separated by a non-magnetic tunnel barrier. Digital information is stored and represented in the memory element as directions of magnetization vectors in the ferromagnetic layers. More specifically, the magnetic moment of one magnetic layer is fixed. Such layer is called the “pinned” or “reference” layer. The magnetic moment of the other magnetic layer may be switched to be either parallel or antiparallel to the pinned layer. This layer is called the “free” or “soft” layer. When the orientations in the pinned layer and the free layer are parallel, the MTJ is in a first state having a first electrical resistance. On the other hand, when the orientations in the pinned layer and the free layer are antiparallel, the MTJ is in a second state, in which its electrical resistance is significantly higher than in the first state. In general, the device state is determined by the orientation of the magnetic films in closest proximity to the tunnel barrier, even if the pinned and free layers are themselves comprised of multiple layers of materials. Such composite pinned and free layers are common, as they can enhance device operation and lifetime. The patterning of the MTJ device is one of the most challenging aspects of fabrication. Conventional techniques used to pattern other structures of a chip, such as reactive ion etching (RIE) or ion milling, have been less than satisfactory when applied to the materials that compose magnetic stacks. In most cases utilizing such techniques, it is extremely difficult to cleanly remove etched material. Physical sputtering, often the dominant component of magnetic material RIE, usually results in the formation of re-deposited residues (called “fences” or “veils”) that can short circuit the junctions of the MTJ, as well as short circuit conductive patterns in different metal layers. Short circuiting may occur either immediately as a result of such fence residues, or after subsequent high temperature processing. Another problem of conventional etch techniques is corrosion and degradation of the patterned free and pinned layers that form the MTJ, due to chemical residue remaining after etching. Exposure to reactive gases during deposition of dielectrics such as silicon nitride and silicon dioxide after the etching of the MTJ can also cause corrosion and degradation. For example, fluorine and/or chlorine species may be present when plasma-etching a stack of magnetic films. Chlorine and fluorine species can combine with conductive and photoresist material removed in the process to deposit a conductive residue along sidewalls of the stack. When subjected to high temperatures, the residue can migrate and cause corrosion, degradation and electrical shorting. One way proposed for handling these problems is development of a process having better selective etch control to minimize exposure of sensitive interfaces to corrosive chemicals and conductive fences. Such etch process should have high selectivity, in order for etching to stop when the thin tunnel barrier layer of a magnetic film stack is reached. Such etch process is known as stop on alumina (SOA), named historically because many of the MTJ tunnel barriers are formed from alumina-type compounds. However, the tight process control and high selectivity required to maintain an acceptably controlled etch process across an entire wafer is difficult to achieve. Moreover, the SOA process does not necessarily protect the free layer from harmful corrosion and degradation. Accordingly, it is desirable to provide an improved structure and method for patterning magnetic tunnel junctions of an MRAM.

<SOH> SUMMARY OF INVENTION <EOH>According to an aspect of the invention, a method of patterning a magnetic tunnel junction (MTJ) stack is provided. According to such method, an MTJ stack is formed having a free layer, a pinned layer and a tunnel barrier layer disposed between the free layer and the pinned layer. A first area of the MTJ stack is masked while the free layer of the MTJ is exposed in a second area. The free layer is then rendered electrically and magnetically inactive in the second area. According to another aspect of the invention, a method is provided for patterning an MTJ stack of a magneto-resistive random access memory (MRAM). Such method includes forming an interlevel dielectric layer (ILD) over a substrate, the ILD including a plurality of conductive lines and vias. An MTJ stack is then formed overlying the ILD, the MTJ stack including a pinned layer, a tunnel barrier layer overlying the pinned layer, and a free layer overlying the tunnel barrier layer. A portion of the MTJ stack is masked to expose an area of the free layer. The exposed area is then converted to a non-magnetic compound by altering its composition. According to yet another aspect of the invention, a structure including a magnetic tunnel junction (MTJ) is provided. Such structure includes an MTJ stack having a first portion of a pinned layer, a first portion of a tunnel barrier layer overlying the first portion of the pinned layer, and a free layer overlying the first portion of the tunnel barrier layer. The structure further includes a layered stack abutting one or more peripheral edges of the MTJ stack, the layered stack including a second portion of the pinned layer, a second portion of the tunnel barrier layer, and an electrically and magnetically inactive compound of a material included in the free layer.

20040611

20070501

20051215

83176.0

LE, DUNG ANH

METHOD OF PATTERNING A MAGNETIC TUNNEL JUNCTION STACK FOR A MAGNETO-RESISTIVE RANDOM ACCESS MEMORY

UNDISCOUNTED

ACCEPTED

ACCEPTED

[THIN FILM TRANSISTOR ARRAY SUBSTRATE AND REPAIRING METHOD THEREOF]

A thin film transistor (TFT) array substrate including a substrate, a plurality of scan lines, a plurality of data lines, a plurality of thin film transistors, a plurality of pixel electrodes and a repairing circuit is provided. The scan lines and the data lines are disposed over the substrate, therefore a plurality of pixel areas are defined. Each thin film transistor is disposed in each pixel area respectively and driven by the corresponding scan line and data line. Each pixel electrode is disposed in each pixel area respectively and electrically connected to the corresponding thin film transistor. A repairing method for TFT array substrate is also provided. The method includes connecting the repairing circuit and the defect scan line besides the break to repair and convert the line defect into two-point defect, single defect, or totally repair the line defect.

1. A thin film transistor (TFT) array substrate, comprising: a substrate; a plurality of scan lines, disposed over the substrate, wherein the scan lines comprise at least a defect scan line comprising a break; a plurality of data lines, disposed over the substrate, wherein a plurality of pixel areas are defined by the scan lines and the data lines; a plurality of thin film transistors, connected with the scan lines and the data lines, wherein each of the thin film transistors is disposed in one of the pixel areas; a plurality of pixel electrodes, wherein each of the pixel electrodes is disposed in one of the pixel areas and electrically connected to one of the thin film transistors correspondingly, and a portion of each of the pixel electrodes is disposed over one of the scan lines correspondingly to construct a storage capacitor; and a repairing circuit, disposed over the break for electrically connecting the defect scan line at two sides of the break, wherein the repairing circuit is electrically insulated with the pixel electrodes. 2. The TET array substrate of claim 1, wherein the break of the defect scan line is between two of the data lines and one of the pixel electrodes comprises an opening corresponding to the break, wherein the repairing circuit is disposed in the opening to be electrically insulated with the one of the pixel electrodes. 3. The TFT array substrate of claim 1, wherein the break of the defect scan line is under one of the data lines and a gap is formed at an edge of two of the pixel electrodes adjacent to the break, wherein the repairing circuit crosses over one of the data lines and is in the gap to be electrically insulated with the pixel electrodes. 4. A thin film transistor (TFT) array substrate, comprising: a substrate; a plurality of scan lines, disposed over the substrate, wherein the scan lines comprise at least a defect scan line comprising a break; a plurality of data lines, disposed over the substrate, wherein a plurality of pixel areas are defined by the scan lines and the data lines; a plurality of thin film transistors, connected with the scan lines and the data lines, wherein each of the thin film transistors is disposed in one of the pixel areas; a plurality of pixel electrodes, wherein each of the pixel electrodes is disposed in one of the pixel areas and electrically connected to one of the thin film transistors correspondingly, and a portion of each of the pixel electrodes is disposed over one of the scan lines correspondingly to construct a storage capacitor; and a repairing circuit, disposed over the break, wherein the repairing circuit and at least one of the pixel electrodes are electrically connected with the defect scan lines at two sides of the break. 5. The TFT array substrate of claim 4, wherein the break of the defect scan line is under one of the data lines and two of the pixel electrodes adjacent to the break of the defect scan line respectively comprises: a displaying portion; and a repairing portion, electrically insulated with the displaying portion, wherein the repairing circuit and the repairing portion are electrically connected to the defect scan line at two sides of the break. 6. A thin film transistor (TFT) array substrate, comprising: a substrate; a plurality of scan lines, disposed over the substrate, wherein the scan lines comprise at least a defect scan line comprising a break; a plurality of data lines, disposed over the substrate, wherein a plurality of pixel areas are defined by the scan lines and the data lines; a plurality of thin film transistors, connected with the scan lines and the data lines, wherein each of the thin film transistors is disposed in one of the pixel areas; and a plurality of pixel electrodes, wherein each of the pixel electrodes is disposed in one of the pixel areas and electrically connected to one of the thin film transistors correspondingly, and a portion of each of the pixel electrodes is disposed over one of the scan lines correspondingly to construct a storage capacitor, wherein at least one of the pixel electrodes is electrically connected to the defeat scan line at two sides of the break. 7. The TFT array substrate of claim 6, wherein the break of the defect scan line is between two of the data lines and one of the pixel electrodes comprises: a displaying portion; and a repairing portion, electrically insulated with the displaying portion, wherein the repairing circuit and the repairing portion are electrically connected to the defect scan line at two sides of the break. 8. The TFT array substrate of claim 6, wherein the break of the defect scan line is under one of the data lines, further comprises: a repairing circuit, crossing over one of the data lines, wherein the repairing line, two of the pixel electrodes adjacent to the break and the defect scan line at two sides of the break are electrically connected mutually. 9. A thin film transistor (TFT) array substrate, comprising: a substrate; a plurality of scan lines, disposed over the substrate; a plurality of data lines, disposed over the substrate, wherein a plurality of pixel areas are defined by the scan lines and the data lines; a plurality of thin film transistors, connected with the scan lines and the data lines, wherein each of the thin film transistors is disposed in one of the pixel areas; and a plurality of pixel electrodes, wherein each of the pixel electrodes is disposed in one of the pixel areas and electrically connected to one of the thin film transistors correspondingly; a plurality of common lines, disposed over the substrate, and a portion of each of the pixel electrodes is disposed over one of the common lines correspondingly to construct a storage capacitor, and the common lines comprise at least a defect common line comprising a break; and a repairing circuit, disposed over the break and electrically connected with the defect common line at two sides of the break, wherein the repairing circuit is electrically insulated with the pixel electrodes. 10. The TFT array substrate of claim 9, wherein the break of the defect common line is between two of the data lines, and one of the pixel electrodes comprises an opening corresponding to the break, and the repairing circuit is disposed in the opening to be electrically insulated with one of the pixel electrodes. 11. The TFT array substrate of claim 9, wherein the break of the defect common line is under one of the data lines, and a gap is formed at an edge of two of the pixel electrodes adjacent to the break, and the repairing circuit crosses over one of the data lines and is in the gap to be electrically insulated with the pixel electrodes. 12. A thin film transistor (TFT) array substrate, comprising: a substrate; a plurality of scan lines, disposed over the substrate; a plurality of data lines, disposed over the substrate, wherein a plurality of pixel areas are defined by the scan lines and the data lines; a plurality of thin film transistors, connected with the scan lines and the data lines, wherein each of the thin film transistors is disposed in one of the pixel areas; and a plurality of pixel electrodes, wherein each of the pixel electrodes is disposed in one of the pixel areas and electrically connected to one of the tin film transistors correspondingly, a plurality of common lines, disposed over the substrate, and a portion of each of the pixel electrodes is disposed over one of the common lines correspondingly to construct a storage capacitor, and the common lines comprise at least a defect common line comprising a break; and a repairing circuit, disposed over the break, wherein the repairing circuit and at least one of the pixel electrodes are electrically connected to the defect common line at two sides of the break. 13. The TFT array substrate of claim 12, wherein the break of the defect common line is under one of the data lines and two of the pixel electrodes adjacent to the break of the defect common line respectively comprise: a displaying portion; and a repairing portion, electrically insulated with the displaying portion, wherein the repairing circuit and the repairing portion are electrically connected to the defect common line at two sides of the break. 14. A thin film transistor (TFT) array substrate, comprising: a substrate; a plurality of scan lines, disposed over the substrate; a plurality of data lines, disposed over the substrate, wherein a plurality of pixel areas are defined by the scan lines and the data lines; a plurality of thin film transistors, connected with the scan lines and the data lines, wherein each of the thin film transistors is disposed in one of the pixel areas; and a plurality of pixel electrodes, wherein each of the pixel electrodes is disposed in one of the pixel areas and electrically connected to one of the thin film transistors correspondingly; and a plurality of common lines, disposed over the substrate, and a portion of each of the pixel electrodes is disposed over one of the common lines correspondingly to construct a storage capacitor, and the common lines comprise at least a defect common line comprising a break, wherein at least one of the pixel electrodes is electrically connected to the defect common line at two sides of the break. 15. The TFT array substrate of claim 14, wherein the break of the defect common line is between two of the data lines and one of the pixel electrodes comprises: a displaying portion; and a repairing portion, electrically insulated with the displaying portion, wherein the repairing circuit and the repairing portion are electrically connected to the defect common line at two sides of the break. 16. The TFT array substrate of claim 14, wherein the break of the defect common line is under one of the data lines, further comprises: a repairing circuit, crossing over one of the data lines, wherein the repairing line, two of the pixel electrodes adjacent to the break and the defect common line at two sides of the break are electrically connected mutually. 17-29. (canceled)

CROSS REFERENCE TO RELATED APPLICATIONS This application claims the priority benefit of Taiwan application serial no. 93111175, filed Apr. 23, 2004. BACKGROUND OF INVENTION 1. Field of the Invention The present invention relates to a thin film transistor (TFT) array substrate and a repairing method thereof. More particularly, the present invention relates to a TFT array substrate and a repairing method thereof for repairing a break of the scan line or the common line of the substrate. 2. Description of the Related Art Recently, a variety of factories have exerted great effort on the development of display device since the requirement and the market of display device has grown rapidly. Conventionally, since the cathode ray tube (CRT) is fully developed and has good display quality, the CRT has been adopted in a variety of application. However, the CRT has the disadvantages of high power consumption, heavy weight, larger size and high radiation and can not meet the requirement of environmental protection. Therefore, the thin film transistor liquid crystal display (TFT-LCD) has been developed and become the major trend of the display device due to the advantages of high definition, small size, thin thickness, low power consumption, radiation free. Conventionally, TFT LCD is mainly constructed by thin film transistor (TFT) array substrate, color filter array substrate and liquid crystal layer. The TFT array substrate is constructed by a plurality of thin film transistors and pixel electrodes disposed corresponding to the thin film transistors. The thin film transistors are adopted as the switching component of the pixel units of the liquid crystal display. The pixel unit is selected and controlled via the corresponding scan line and data line. Then, an applicable operation voltage is applied to the pixel unit to display a displaying data on the pixel. Generally, a portion of the pixel electrode described above is covered on the scan line or the common line, and the overlapped portion of the pixel electrodes is adopted as a storage capacitor (Cst). Therefore, the pixels of the TFT LCD may be operated for displaying the images by the storage capacitors. It is noted that, a problem of line defect may be generated in the conventional TFT array substrate due to the break of the lines such as the scan line or the common line of the TFT array substrate. Therefore, the TFT array substrate is damaged and may be withdrawn. SUMMARY OF INVENTION Therefore, the present invention is directed to a TFT array substrate and a repairing method thereof for repairing a break of the scan line or the common line to avoid the withdrawal of the TFT array substrate. In accordance with one embodiment of the present invention, a thin film transistor (TFT) array substrate including a substrate, a plurality of scan lines, a plurality of data lines, a plurality of thin film transistors, a plurality of pixel electrodes and a repairing circuit is provided. The scan lines are disposed over the substrate and include at least a defect scan line having a break, and the data lines are disposed over the substrate. Therefore, a plurality of pixel areas are defined by the scan lines and the data lines. Each thin film transistor is disposed in one of the pixel areas, and the thin film transistors are connected with and driven via the scan lines and the data lines. Each pixel electrode is disposed in one of the pixel areas and electrically connected to one of the thin film transistors correspondingly, and a portion of each of the pixel electrodes is disposed over one of the scan lines correspondingly to construct a storage capacitor. The repairing circuit is disposed over the break for electrically connecting the defect scan line at two sides of the break, wherein the repairing circuit is electrically insulated with the pixel electrodes. In accordance with one embodiment of the present invention, a thin film transistor (TFT) array substrate including a substrate, a plurality of scan lines, a plurality of data lines, a plurality of thin film transistors, a plurality of pixel electrodes and a repairing circuit is provided. The scan lines are disposed over the substrate and include at least a defect scan line having a break, the data lines are disposed over the substrate. Therefore, a plurality of pixel areas are defined by the scan lines and the data lines. Each thin film transistor is disposed in one of the pixel areas, and the thin film transistors are connected with and driven via the scan lines and the data lines. Each pixel electrode is disposed in one of the pixel areas and electrically connected to one of the thin film transistors correspondingly, and a portion of each of the pixel electrodes is disposed over one of the scan lines correspondingly to construct a storage capacitor. The repairing circuit is disposed over the break, wherein the repairing circuit and at least one of the pixel electrodes is electrically connected with the defect scan lines at two sides of the break. In accordance with one embodiment of the present invention, a thin film transistor (TFT) array substrate including a substrate, a plurality of scan lines, a plurality of data lines, a plurality of thin film transistors and a plurality of pixel electrodes is provided. The scan lines are disposed over the substrate and include at least a defect scan line having a break, and the data lines are disposed over the substrate. Therefore, a plurality of pixel areas are defined by the scan lines and the data lines. Each thin film transistor is disposed in one of the pixel areas, and the thin film transistors are connected with and driven via the scan lines and the data lines. Each pixel electrode is disposed in one of the pixel areas and electrically connected to one of the thin film transistors correspondingly, and a portion of each of the pixel electrodes is disposed over one of the scan lines correspondingly to construct a storage capacitor. Therefore, at least one of the pixel electrodes is electrically connected to the defect scan line at two sides of the break. In accordance with one embodiment of the present invention, a thin film transistor (TFT) array substrate including a substrate, a plurality of scan lines, a plurality of data lines, a plurality of thin film transistors, a plurality of pixel electrodes, a plurality of common line and a repairing circuit is provided. The scan lines and the data lines are disposed over the substrate, therefore a plurality of pixel areas are defined by the scan lines and the data lines. Each thin film transistor is disposed in one of the pixel areas, and the thin film transistors are connected with and driven via the scan lines and the data lines. Each pixel electrode is disposed in one of the pixel areas and electrically connected to one of the thin film transistors correspondingly. The common lines are disposed over the substrate, and a portion of each of the pixel electrodes is disposed over one of the common lines correspondingly to construct a storage capacitor, wherein the common lines comprise at least a defect common line comprising a break. The repairing circuit is disposed over the break for electrically connecting the defect scan line at two sides of the break, wherein the repairing circuit is electrically insulated with the pixel electrodes. In accordance with one embodiment of the present invention, a thin film transistor (TFT) array substrate including a substrate, a plurality of scan lines, a plurality of data lines, a plurality of thin film transistors, a plurality of pixel electrodes, a plurality of common line and a repairing circuit is provided. The scan lines and the data lines are disposed over the substrate, therefore a plurality of pixel areas are defined by the scan lines and the data lines. Each thin film transistor is disposed in one of the pixel areas, and the thin film transistors are connected with and driven via the scan lines and the data lines. Each pixel electrode is disposed in one of the pixel areas and electrically connected to one of the thin film transistors correspondingly. The common lines are disposed over the substrate, and a portion of each of the pixel electrodes is disposed over one of the common lines correspondingly to construct a storage capacitor, wherein the common lines comprise at least a defect common line comprising a break. The repairing circuit is disposed over the break, wherein the repairing circuit and at least one of the pixel electrodes are electrically connected to the defect common line at two sides of the break. In accordance with one embodiment of the present invention, a thin film transistor (TFT) array substrate including a substrate, a plurality of scan lines, a plurality of data lines, a plurality of thin film transistors, a plurality of pixel electrodes and a plurality of common line is provided. The scan lines and the data lines are disposed over the substrate, therefore a plurality of pixel areas are defined by the scan lines and the data lines. Each thin film transistor is disposed in one of the pixel areas, and the thin film transistors are connected with and driven via the scan lines and the data lines. Each pixel electrodes is disposed in one of the pixel areas and electrically connected to one of the thin film transistors correspondingly. The common lines are disposed over the substrate, and a portion of each of the pixel electrodes is disposed over one of the common lines correspondingly to construct a storage capacitor, wherein the common lines comprise at least a defect common line comprising a break. In addition, at least one of the pixel electrodes is electrically connected to the defect common line at two sides of the break. In accordance with one embodiment of the present invention, a repairing method of a thin film transistor (TFT) array substrate for repairing a TFT array substrate comprising a storage capacitor on a gate (Cst on gate) or a storage capacitor on a common line (Cst on common) is provided. The repairing method includes, for example but not limited to, the following steps. First, a portion of at least one pixel electrode adjacent to a break of a scan line or a common line is removed. Then, a repairing circuit over the break is formed to electrically connect the repairing circuit and the scan line at two sides of the break or electrically connect the repairing circuit and the common line at two sides of the break, wherein the repairing circuit is electrically insulated with the pixel electrodes. In accordance with one embodiment of the present invention, a repairing method of a thin film transistor (TFT) array substrate for repairing a TFT array substrate comprising a storage capacitor on a gate or a storage capacitor on a common line is provided. The repairing method includes, for example but not limited to, the following steps. Wherein, a portion of at least one pixel electrode adjacent to a break of a scan line or a common line is removed to electrically connect a portion of the pixel electrode with the scan line or the common line at two sides of the break. In accordance with one embodiment of the present invention, a repairing method of a thin film transistor (TFT) array substrate for repairing a TFT array substrate comprising a storage capacitor on a gate or a storage capacitor on a common line is provided. The repairing method includes, for example but not limited to, the following steps. Wherein, at least one pixel electrode adjacent to a break of a scan line or a common line is electrically connected to the scan line or the common line at two sides of the break. Accordingly, the present invention provides a repairing circuit for repairing the break of the scan line or the common line of the TFT array substrate. The defect scan line or the defect common line is repaired by electrically connecting the repairing circuit to the scan line or the common line at two sides of the break. In addition, the defect scan line or the defect common line may also be repaired by directly connecting the pixel electrode disposed over the break top to the scan line or the common line at two sides of the break. One or parts or all of these and other features and advantages of the present invention will become readily apparent to those skilled in this art from the following description wherein there is shown and described a preferred embodiment of this invention, simply by way of illustration of one of the modes best suited to carry out the invention. As it will be realized, the invention is capable of different embodiments, and its several details are capable of modifications in various, obvious aspects all without departing from the invention. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive. BRIEF DESCRIPTION OF DRAWINGS The accompanying drawings are included to provide a further understanding of the present invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention. FIG. 1 is a schematic top view illustrates a thin film transistor (TFT) array substrate of storage capacitor on a gate according to one embodiment of the present invention. FIG. 2A to FIG. 2F are top views schematically illustrating a method for repairing the defect scan line shown in FIG. 1 according to embodiments of the present invention. FIG. 3A to FIG. 3F are top views schematically illustrating a method for repairing a defect common line according to embodiments of the present invention. DETAILED DESCRIPTION The present invention will be described fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the present invention are illustrated. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements in the accompanying drawings throughout. FIG. 1 is a schematic top view illustrates a thin film transistor (TFT) array substrate of a storage capacitor on a gate according to one embodiment of the present invention. Referring to FIG. 1, a thin film transistor (TFT) array substrate comprises, for example but not limited to, a substrate 100, a plurality of scan lines 110, a plurality of data lines 120, a plurality of thin film transistors 130 and a plurality of pixel electrodes 140. The scan lines 110 and the data lines 120 are disposed over the substrate 100, and a plurality of pixel areas 122 are defined by the scan lines 110 and the data lines 120. Each thin film transistor 130 is disposed in the corresponding pixel area 122, and the thin film transistors 130 are connected with and driven via the scan lines 110 and the data lines 120. Each pixel electrode 140 is disposed in the corresponding pixel area 122 to be electrically connected to the corresponding thin film transistor 130. In addition, a portion of each pixel electrode 140 is disposed over the corresponding scan line 110 to construct a storage capacitor. Therefore, the storage capacitor is constructed by the coupling of the scan line 110 and the pixel electrode 140 over the scan line 110, wherein a dielectric layer, for example but not limited to, a gate isolation layer and/or a protection layer is disposed between the scan line 110 and the pixel electrode 140. It is noted that, sometimes at least a defect scan line 110a may be generated in the scan lines 110 due to the defect in the process or other reasons. The defect scan line 110a generally comprises at least a break A. When a defect scan line 110a is generated in the scan lines 110, the pixel electrodes 140 connected after the break of the defect scan line 110a dont work for displaying normally. Hereinafter, in the present invention, a break A of the defect scan line 110a disposed between any two data lines 120 or under any data line 120 will be illustrated as an exemplary embodiment. In addition, a plurality of repairing methods for repairing the defect scan line 110a will also be described. However, the present invention should not be limited to the embodiments and the descriptions of the invention. FIG. 2A to FIG. 2F are top views schematically illustrating a repairing method corresponding to the defect scan line shown in FIG. 1 according to embodiments of the present invention. Referring to FIG. 2A, if the break A of the defect scan line 110a is disposed between any two of the data lines 120, the defect scan line 110a may be repaired by, for example but not limited to, the following steps. First, a portion of the pixel electrode 140 above the break A is removed by using, for example but not limited to, a laser removing method. In one embodiment of the present, an opening 142 may be formed after the portion of the pixel electrode 140 is removed. Thereafter, a repairing circuit 150 may be formed in the opening 142 by using, for example but not limited to, a laser chemical vapor deposition (CVD) method. It is noted that, the repairing circuit 150 and the defect scan line 110a at two sides of the break A are electrically connected by using, for example but not limited to, a laser welding method. Alternatively, referring to FIG. 2B, if the break A of the defect scan line 110a is disposed under one of the data lines 120, the defect scan line 110a may be repaired by, for example but not limited to, the following steps. First, a portion of two pixel electrodes 140 adjacent to the break A is removed by using, for example but not limited to, a laser removing method. In one embodiment of the present invention, a gap 144 may be formed by removing the edges of the two pixel electrodes 140 respectively. In addition, a repairing circuit 150 is formed in the gap 144 and crosses over the data line 120 by using, for example but not limited to, a laser chemical vapor deposition (CVD) method. It is noted that, the repairing circuit 150 and the defect scan line 110a at two sides of the break A are electrically connected by using, for example but not limited to, a laser welding method. Accordingly, in the repairing method illustrated in FIG. 2A or FIG. 2B, since the repairing circuit 150 and the repaired pixel electrodes 140 are electrically insulated mutually, the repaired pixel electrode 140 can be used for displaying normally. Moreover, referring to FIG. 2C, when the break A of the defect scan line 110a is disposed under one of the data lines 120, the defect scan line 110a may be repaired by, for example but not limited to, the following steps. First, the two pixel electrodes 140 adjacent to the break A are divided into a displaying portion 140a and a repairing portion 140b, wherein the displaying portion 140a and the repairing portion 140b are electrically insulated. In one embodiment of the present embodiment, the two pixel electrodes 140 are divided by using, for example but not limited to, a laser removing method. In addition, a repairing circuit 150 is formed over the break A, therefore the repairing circuit 150 and the repairing portion 140b may be electrically connected to the defect scan line 110a at two sides of the break A. It is noted that, the repairing circuit 150 is electrically connected to the defect scan line 110a at two sides of the break A and the repairing portion 140b by using, for example but not limited to, a laser welding method. Alternatively, referring to FIG. 2D, when the break A of the defect scan line 110a is disposed between any two data lines 120, the defect scan line 110a may be repaired by, for example but not limited to, the following method. First, the pixel electrode 140 over the break A is divided into a displaying portion 140a and a repairing portion 140b surrounded by the displaying portion 140a. The displaying portion 140a and the repairing portion 140b are electrically insulated. In one embodiment of the present invention, the pixel electrode 140 is divided by using, for example but not limited to, a laser removing method. Thereafter, the repairing portion 140b is electrically connected to the defect scan line 110a at two sides of the break A. In one embodiment of the present invention, the repairing portion 140b and the defect scan line 110a at two sides of the break A are electrically connected by using, for example but not limited to, a laser welding method. Accordingly, in the repairing method shown in FIG. 2C and FIG. 2D, the pixel electrode 140 adjacent to the break A is divided into the displaying portion 140a and the repairing portion 140b. Then, the repairing portion 140b is electrically connected to the defect scan line 110a at two sides of the break A, therefore the break A is repaired. It is noted that, since the displaying portion 140a and the repairing portion 140b of the pixel electrode 140 are electrically insulated mutually, the displaying portion 140a of the pixel electrode 140 can also be used for displaying normally and is not influenced by the repairing process. Referring to FIG. 2E, when the break A of the defect scan line 110a is disposed between any two of the data lines 120, the defect scan line 110a may be repaired by, for example but not limited to, a laser welding method to electrically connect the pixel electrode 140 over the break A and the defect scan line 110a at two sides of the break A directly. Therefore, since the defect scan line 110a is repaired by the pixel electrode 140 over the break A, the line defect may be repaired and converted into a single defect. Alternatively, referring to FIG. 2F, when the break A of the defect scan line 110a is disposed under one of the data lines 120, the defect scan line 110a may be repaired by, for example but not limited to, forming a repairing circuit 150 over the break A. In one embodiment of the present invention, the repairing circuit 150 is formed by, for example but not limited to, a laser chemical vapor deposition (CVD) method. It is noted that, the repairing circuit 150 is electrically connected to the defect common line 110a at two sides of the break A and the pixel electrode 140 at two sides of the break A by using, for example but not limited to, a laser welding method. Accordingly, in the repairing method illustrated in FIG. 2E and FIG. 2F, the line defect can be repaired by electrically connecting the pixel electrode 140 to the defect scan line 110a at two sides of the break A directly. Accordingly, the embodiments described above are provided for repairing the break of the defect scan line. However, the repairing method of the present invention is not only limited to the method of repairing the defect scan line, but also can be provided for repairing. For example but not limited to, the defect common line of the TFT array substrate. In general, the common line is disposed between every two adjacent scan lines, and the common line may be covered by a portion of the pixel electrode to form a storage capacitor on a common line (Cst on common). Therefore, when the defect common line of the common line is broken, a problem of line defect is also generated. Therefore, the present invention provides another repairing method for repairing the defect common line. FIG. 3A to FIG. 3F are top views schematically illustrating a method for repairing a defect common line according to embodiments of the present invention. The TFT array substrate shown in FIG. 3A to FIG. 3F comprises a TFT array substrate of a storage capacitor on a common line (Cst on common) and has a structure similar to FIG. 2A to FIG. 2F. Therefore, only the technology different to the embodiments described above will be described in detail hereinafter. In the structure of a storage capacitor on a common line (Cst on common), a common line 160 is disposed between any two adjacent scan lines 110 of the substrate 100. The storage capacitor (not shown) in each pixel is constructed from a portion of the pixel electrode 140 and the common line 160 over the pixel electrode 140. Similarly, the common line 160 and the pixel electrode 140 are generally separated by a dielectric layer (not shown), for example but not limited to, a gate isolation layer (not shown) and/or a protection layer (not shown). In general, at least a defect common line 160a may be formed in the common lines 160, and the defect common line 160a comprises a break B. Referring to FIG. 3A, when the break B of the defect common line 160a is disposed between any two of the data lines 120, the defect common line 160a may be repairing by using, for example but not limited to, the following steps. First, a portion of the pixel electrode 140 over the break B is removed to form an opening 142. Thereafter, a repairing circuit 150 is formed in the opening 142 to electrically connect the repairing circuit 150 to the defect common line 160a at two sides of the break B. Thus, the defect common line 160a is repaired. Referring to FIG. 3B, in one embodiment of the present invention, a portion of the pixel electrode 140 over the break B is removed to form a display area 140a and an and a repairing area 140b electrically insulated with the display area 140a. Thereafter, the repairing area 140b is electrically connected to the defect common line 160a at two sides of the break B. Referring to FIG. 3C, in one embodiment of the present invention, the pixel electrode 140 over the break B may be electrically connected to the defect common line 160a at two sides of the break B directly by using a laser welding method. Referring to FIG. 3D, when the break B of the defect common line 160a is disposed under one of the data lines 120, the defect common line 160a may be repaired by, for example but not limited to, the following steps. First, a portion of two pixel electrodes 140 adjacent to the break B is removed to form a gap 144 at the edges of the two pixel electrodes 140 respectively. Thereafter, a repairing circuit 150 is formed and crosses over the data line 120, wherein the repairing circuit 150 is in the gap 144 and electrically connected to the defect common line 160a at two sides of the break B. Referring to FIG. 3E, in one embodiment of the present invention, a portion of two pixel electrodes 140 adjacent to the remove break B may also be removed to form a display area 140a and a repairing area 140b electrically insulated with the display area 140a. Thereafter, a repairing circuit 150 is formed and crosses over the data line 120, wherein the repairing circuit 150 is electrically connected to the repairing area 140b and the defect common line 160a at two sides of the break B. Referring to FIG. 3F, in one embodiment of the present invention, a repairing circuit 150 may be directly formed and crosses over the data line 120, and then the repairing circuit 150 is electrically connected to the defect common line 160a at two sides of the break B by using, for example, a laser welding method. Accordingly, the repairing method of the present invention has the following advantages. First, the line defect generated in the scan line or the common line may be easily repaired by the repairing method of the present invention. The present invention is practicable. Next, the repairing method of the present invention is provided for repairing and converting the line defect into a two-point defect, a single defect, or even the defect is totally repaired (zero defect). Therefore, the yield is drastically enhanced. The foregoing description of the preferred embodiment of the present invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form or to exemplary embodiments disclosed. Accordingly, the foregoing description should be regarded as illustrative rather than restrictive. Obviously, many modifications and variations will be apparent to practitioners skilled in this art. The embodiments are chosen and described in order to best explain the principles of the invention and its best mode practical application, thereby to enable persons skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use or implementation contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents in which all terms are meant in their broadest reasonable sense unless otherwise indicated. It should be appreciated that variations may be made in the embodiments described by persons skilled in the art without departing from the scope of the present invention as defined by the following claims. Moreover, no element and component in the present disclosure is intended to be dedicated to the public regardless of whether the element or component is explicitly recited in the following claims.

<SOH> BACKGROUND OF INVENTION <EOH>1. Field of the Invention The present invention relates to a thin film transistor (TFT) array substrate and a repairing method thereof. More particularly, the present invention relates to a TFT array substrate and a repairing method thereof for repairing a break of the scan line or the common line of the substrate. 2. Description of the Related Art Recently, a variety of factories have exerted great effort on the development of display device since the requirement and the market of display device has grown rapidly. Conventionally, since the cathode ray tube (CRT) is fully developed and has good display quality, the CRT has been adopted in a variety of application. However, the CRT has the disadvantages of high power consumption, heavy weight, larger size and high radiation and can not meet the requirement of environmental protection. Therefore, the thin film transistor liquid crystal display (TFT-LCD) has been developed and become the major trend of the display device due to the advantages of high definition, small size, thin thickness, low power consumption, radiation free. Conventionally, TFT LCD is mainly constructed by thin film transistor (TFT) array substrate, color filter array substrate and liquid crystal layer. The TFT array substrate is constructed by a plurality of thin film transistors and pixel electrodes disposed corresponding to the thin film transistors. The thin film transistors are adopted as the switching component of the pixel units of the liquid crystal display. The pixel unit is selected and controlled via the corresponding scan line and data line. Then, an applicable operation voltage is applied to the pixel unit to display a displaying data on the pixel. Generally, a portion of the pixel electrode described above is covered on the scan line or the common line, and the overlapped portion of the pixel electrodes is adopted as a storage capacitor (Cst). Therefore, the pixels of the TFT LCD may be operated for displaying the images by the storage capacitors. It is noted that, a problem of line defect may be generated in the conventional TFT array substrate due to the break of the lines such as the scan line or the common line of the TFT array substrate. Therefore, the TFT array substrate is damaged and may be withdrawn.

<SOH> SUMMARY OF INVENTION <EOH>Therefore, the present invention is directed to a TFT array substrate and a repairing method thereof for repairing a break of the scan line or the common line to avoid the withdrawal of the TFT array substrate. In accordance with one embodiment of the present invention, a thin film transistor (TFT) array substrate including a substrate, a plurality of scan lines, a plurality of data lines, a plurality of thin film transistors, a plurality of pixel electrodes and a repairing circuit is provided. The scan lines are disposed over the substrate and include at least a defect scan line having a break, and the data lines are disposed over the substrate. Therefore, a plurality of pixel areas are defined by the scan lines and the data lines. Each thin film transistor is disposed in one of the pixel areas, and the thin film transistors are connected with and driven via the scan lines and the data lines. Each pixel electrode is disposed in one of the pixel areas and electrically connected to one of the thin film transistors correspondingly, and a portion of each of the pixel electrodes is disposed over one of the scan lines correspondingly to construct a storage capacitor. The repairing circuit is disposed over the break for electrically connecting the defect scan line at two sides of the break, wherein the repairing circuit is electrically insulated with the pixel electrodes. In accordance with one embodiment of the present invention, a thin film transistor (TFT) array substrate including a substrate, a plurality of scan lines, a plurality of data lines, a plurality of thin film transistors, a plurality of pixel electrodes and a repairing circuit is provided. The scan lines are disposed over the substrate and include at least a defect scan line having a break, the data lines are disposed over the substrate. Therefore, a plurality of pixel areas are defined by the scan lines and the data lines. Each thin film transistor is disposed in one of the pixel areas, and the thin film transistors are connected with and driven via the scan lines and the data lines. Each pixel electrode is disposed in one of the pixel areas and electrically connected to one of the thin film transistors correspondingly, and a portion of each of the pixel electrodes is disposed over one of the scan lines correspondingly to construct a storage capacitor. The repairing circuit is disposed over the break, wherein the repairing circuit and at least one of the pixel electrodes is electrically connected with the defect scan lines at two sides of the break. In accordance with one embodiment of the present invention, a thin film transistor (TFT) array substrate including a substrate, a plurality of scan lines, a plurality of data lines, a plurality of thin film transistors and a plurality of pixel electrodes is provided. The scan lines are disposed over the substrate and include at least a defect scan line having a break, and the data lines are disposed over the substrate. Therefore, a plurality of pixel areas are defined by the scan lines and the data lines. Each thin film transistor is disposed in one of the pixel areas, and the thin film transistors are connected with and driven via the scan lines and the data lines. Each pixel electrode is disposed in one of the pixel areas and electrically connected to one of the thin film transistors correspondingly, and a portion of each of the pixel electrodes is disposed over one of the scan lines correspondingly to construct a storage capacitor. Therefore, at least one of the pixel electrodes is electrically connected to the defect scan line at two sides of the break. In accordance with one embodiment of the present invention, a thin film transistor (TFT) array substrate including a substrate, a plurality of scan lines, a plurality of data lines, a plurality of thin film transistors, a plurality of pixel electrodes, a plurality of common line and a repairing circuit is provided. The scan lines and the data lines are disposed over the substrate, therefore a plurality of pixel areas are defined by the scan lines and the data lines. Each thin film transistor is disposed in one of the pixel areas, and the thin film transistors are connected with and driven via the scan lines and the data lines. Each pixel electrode is disposed in one of the pixel areas and electrically connected to one of the thin film transistors correspondingly. The common lines are disposed over the substrate, and a portion of each of the pixel electrodes is disposed over one of the common lines correspondingly to construct a storage capacitor, wherein the common lines comprise at least a defect common line comprising a break. The repairing circuit is disposed over the break for electrically connecting the defect scan line at two sides of the break, wherein the repairing circuit is electrically insulated with the pixel electrodes. In accordance with one embodiment of the present invention, a thin film transistor (TFT) array substrate including a substrate, a plurality of scan lines, a plurality of data lines, a plurality of thin film transistors, a plurality of pixel electrodes, a plurality of common line and a repairing circuit is provided. The scan lines and the data lines are disposed over the substrate, therefore a plurality of pixel areas are defined by the scan lines and the data lines. Each thin film transistor is disposed in one of the pixel areas, and the thin film transistors are connected with and driven via the scan lines and the data lines. Each pixel electrode is disposed in one of the pixel areas and electrically connected to one of the thin film transistors correspondingly. The common lines are disposed over the substrate, and a portion of each of the pixel electrodes is disposed over one of the common lines correspondingly to construct a storage capacitor, wherein the common lines comprise at least a defect common line comprising a break. The repairing circuit is disposed over the break, wherein the repairing circuit and at least one of the pixel electrodes are electrically connected to the defect common line at two sides of the break. In accordance with one embodiment of the present invention, a thin film transistor (TFT) array substrate including a substrate, a plurality of scan lines, a plurality of data lines, a plurality of thin film transistors, a plurality of pixel electrodes and a plurality of common line is provided. The scan lines and the data lines are disposed over the substrate, therefore a plurality of pixel areas are defined by the scan lines and the data lines. Each thin film transistor is disposed in one of the pixel areas, and the thin film transistors are connected with and driven via the scan lines and the data lines. Each pixel electrodes is disposed in one of the pixel areas and electrically connected to one of the thin film transistors correspondingly. The common lines are disposed over the substrate, and a portion of each of the pixel electrodes is disposed over one of the common lines correspondingly to construct a storage capacitor, wherein the common lines comprise at least a defect common line comprising a break. In addition, at least one of the pixel electrodes is electrically connected to the defect common line at two sides of the break. In accordance with one embodiment of the present invention, a repairing method of a thin film transistor (TFT) array substrate for repairing a TFT array substrate comprising a storage capacitor on a gate (Cst on gate) or a storage capacitor on a common line (Cst on common) is provided. The repairing method includes, for example but not limited to, the following steps. First, a portion of at least one pixel electrode adjacent to a break of a scan line or a common line is removed. Then, a repairing circuit over the break is formed to electrically connect the repairing circuit and the scan line at two sides of the break or electrically connect the repairing circuit and the common line at two sides of the break, wherein the repairing circuit is electrically insulated with the pixel electrodes. In accordance with one embodiment of the present invention, a repairing method of a thin film transistor (TFT) array substrate for repairing a TFT array substrate comprising a storage capacitor on a gate or a storage capacitor on a common line is provided. The repairing method includes, for example but not limited to, the following steps. Wherein, a portion of at least one pixel electrode adjacent to a break of a scan line or a common line is removed to electrically connect a portion of the pixel electrode with the scan line or the common line at two sides of the break. In accordance with one embodiment of the present invention, a repairing method of a thin film transistor (TFT) array substrate for repairing a TFT array substrate comprising a storage capacitor on a gate or a storage capacitor on a common line is provided. The repairing method includes, for example but not limited to, the following steps. Wherein, at least one pixel electrode adjacent to a break of a scan line or a common line is electrically connected to the scan line or the common line at two sides of the break. Accordingly, the present invention provides a repairing circuit for repairing the break of the scan line or the common line of the TFT array substrate. The defect scan line or the defect common line is repaired by electrically connecting the repairing circuit to the scan line or the common line at two sides of the break. In addition, the defect scan line or the defect common line may also be repaired by directly connecting the pixel electrode disposed over the break top to the scan line or the common line at two sides of the break. One or parts or all of these and other features and advantages of the present invention will become readily apparent to those skilled in this art from the following description wherein there is shown and described a preferred embodiment of this invention, simply by way of illustration of one of the modes best suited to carry out the invention. As it will be realized, the invention is capable of different embodiments, and its several details are capable of modifications in various, obvious aspects all without departing from the invention. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive.

20040623

20060404

20051117

57929.0

LOUIE, WAI SING

[THIN FILM TRANSISTOR ARRAY SUBSTRATE AND REPAIRING METHOD THEREOF]

UNDISCOUNTED

ACCEPTED

ACCEPTED

METHODS AND SYSTEMS FOR LAYOUT AND ROUTING USING ALTERNATING APERTURE PHASE SHIFT MASKS

Methods for performing phase-correct layout and routing of integrated circuits using alternating aperture phase shift masks (AltPSM), including bright field AltPSM and dark field AltPSM are disclosed. Also disclosed are systems for performing phase-correct layout and routing, including computer-based routing programs and systems.

1. A method of laying out features for alternating aperture phase shift masks, comprising: defining features on a grid of a uniform basic pitch; orienting the features such that those of the features defined, at least in part, by phase shifting shapes are oriented along a primary direction; and spacing two features terminating adjacent one another such that the two features have space between them sufficient to prevent phase conflicts if both of the two features are defined, at least in part, by phase shifting shapes. 2. The method of claim 1, wherein the alternating aperture phase shift mask is a bright field alternating aperture phase shift mask. 3. The method of claim 2, further comprising sizing features or sections of features not oriented along the primary direction so as to be non-critical in dimension. 4. The method of claim 3, wherein the features or sections of features not oriented along the primary direction have a dimension equal to two or more times the uniform basic pitch. 5. The method of claim 1, wherein the alternating aperture phase shift mask is a dark field phase shift mask. 6. The method of claim 5, further comprising spacing pins such that, if oriented in the primary direction, two adjacent pins are placed with greater than the uniform basic pitch between them. 7. The method of claim 5, further comprising orienting substantially all of the features along the primary direction. 8. The method of claim 7, further comprising one or more of laying out features not extending along the primary direction such that the features not extending along the primary direction extend in a non-primary direction for an even number of spaces along the grid; defining the features not extending along the primary direction on a separate integrated circuit layer having a separate primary direction that matches a direction of the features not extending along the primary direction; or spacing the features not extending along the primary direction such that adjacent free space adequate to prevent phase conflicts is provided. 9. A computer-readable medium containing instructions that, when executed, cause a computer to perform the tasks of the method of claim 1. 10. A system for layout and routing of integrated circuits, comprising: a routing module that, when routing wires or features for alternating aperture phase shift masks, considers routes essentially only in a primary wiring direction, and blocks sufficient free space between the end of a first feature and the beginning of a second feature to avoid phase conflicts between the first feature and the second feature. 11. The system of claim 10, wherein the alternating aperture phase shift mask is a dark field alternating aperture phase shift mask. 12. The system of claim 10, wherein the routing module, when routing wires or features for bright field alternating aperture phase shift masks, ensures that wires or features running orthogonally to the primary wiring direction are of non-critical dimensions. 13. The system of claim 10, wherein the routing module defines features on a grid of a uniform basic pitch. 14. The system of claim 13, wherein the routing module routes such that jogs in wires or features: extend an even number of spaces along the grid in a non-primary wiring direction; or are provided with adequate adjacent free space so as to avoid phase conflicts. 15. A computer-readable medium containing instructions which, when executed, cause a computer to produce a substantially phase-correct integrated circuit routing for a plurality of features defined by alternating aperture phase shift masks. 16. The computer-readable medium of claim 15, wherein the routing is produced on a grid of a uniform basic pitch. 17. The computer-readable medium of claim 16, wherein the alternating aperture phase shift mask is a dark field alternating aperture phase shift mask. 18. The computer-readable medium of claim 17, wherein the instructions cause the computer to: consider routes essentially only in a primary wiring direction, and block sufficient free space between the end of a first feature and the beginning of a second feature to avoid phase conflicts between the first feature and the second feature. 19. The computer-readable medium of claim 17, wherein the instructions cause the computer to route wires that would extend in other than the primary wiring direction on another layer of the integrated circuit. 20. The computer-readable medium of claim 17, wherein the instructions cause the computer to route and define wires and features such that jogs in the wires or features: extend an even number of spaces along the grid in a non-primary wiring direction; or are provided with adequate free surrounding space so as to avoid phase conflicts. 21. The computer-readable medium of claim 16, wherein the instructions, when executed, cause a computer to produce a substantially phase-correct integrated circuit routing for a plurality of features produced using bright field alternating aperture phase shift masks. 22. The computer-readable medium of claim 21, wherein the instructions cause the computer to make features not oriented along a primary wiring direction of non-critical dimensions. 23. The computer-readable medium of claim 16, wherein the instructions cause the computer to locate contact pins so as to produce a substantially phase-correct routing.

BACKGROUND OF INVENTION 1. Field of the Invention The invention relates to methods and systems for design, layout, and routing of integrated circuits using alternating aperture phase shift masks. 2. Description of Related Art The features of small integrated circuit semiconductor devices, such as microprocessors, are usually defined by using lithographic techniques on a semiconductor wafer. A typical lithographic mask for semiconductor photolithography processes is a sheet of quartz onto which a layer of chrome or another opaque material is deposited in patterns that define the shapes which are to be reproduced lithographically on the semiconductor wafer. As better technologies have allowed the features of a semiconductor device to become smaller and smaller, feature size has begun to approach the theoretical minimum size that can be faithfully reproduced by conventional lithographic techniques. Therefore, as feature sizes have become smaller and smaller, engineers have turned to a number of Resolution Enhancement Techniques (RET) that improve the resolution of the conventional processes. One RET is a technique known as Alternating Aperture Phase Shift Masks (AltPSM). In general, AltPSM makes use of the constructive and destructive interference of light to sharpen the edges and increase the resolution of lithographically reproduced features. Specifically, some portions of AltPSM masks are etched so as to be thinner, or have additional layers of transparent material deposited on them so as to be thicker. Changing the depth of material through which light passes during lithography alters the phase of the light. By selecting and controlling the depth (i.e., thickness) of the mask, an AltPSM mask can have areas in which the light passing through the mask is 180° out of phase with respect to the other areas of the same mask. When light that is 180° out of phase meets at the wafer, either constructive interference or destructive interference may occur, and the interfering light defines the pattern to which the (usually photoresist-covered) wafer is actually exposed. Typically, light of a particular wavelength (e.g., currently 193 nanometers (nm)) is used in semiconductor lithography. Resolution Enhancement Techniques such as AltPSM may be used to print features smaller than the wavelength of the light. When using AltPSM techniques in integrated circuit design and layout, features that approach the minimum size may be defined, at least in part, by shapes having the phases necessary to cause interference and create the desired feature. Two primary types of AltPSM are in use: bright field and dark field. The two techniques are complements of one another. In bright field AltPSM, phase shifting shapes are added to the layout to sharpen the focus of the design features. In dark field AltPSM, phases are added to the design features themselves to define and sharpen the spaces between the features. For example, FIG. 1 is a depiction of an exemplary phase-correct bright field AltPSM layout 10. The actual shape of the feature 12 is flanked on each side by a phase shape 14, 16. The two phase shapes 14, 16 have phases that are 180° out of phase, so that interference of light will define the desired feature 12. FIG. 2 is a depiction of an exemplary phase-correct dark field AltPSM layout 20. In the dark field layout 20, three wires 22, 24, 26 are given particular phases; the uppermost and lowermost phase wires 22, 26 in FIG. 2 have the same phase, and the center wire 24 has a phase 180° out of phase with the other two wires 22, 26; therefore interference between the center wire 24 and the top and bottom wires 22, 26 will define and sharpen the spaces between the wires. Typically, bright field AltPSM is used for polysilicon layers and dark field AltPSM is used for metal layers (e.g., wiring layers). The overall process of determining the location and phase of AltPSM phase shapes is sometimes referred to as “phase coloring,” particularly in the case of dark field AltPSM, in which phases are added to existing shapes or features. AltPSM layouts and routings may be determined for an entire integrated circuit together, or for smaller individual portions of the circuit, for example, between a certain group of standard or “book” elements in one portion of the integrated circuit. SUMMARY OF INVENTION One aspect of the invention relates to a method for laying out features for alternating aperture phase shift masks. The method comprises defining features on a grid of a uniform basic pitch. The method also comprises orienting the features such that those of the features defined, at least in part, by phase shifting shapes are oriented along a primary direction, and spacing two features terminating adjacent one another such that the two features have space between them sufficient to prevent phase conflicts if both of the two features are defined, at least in part, by phase shifting shapes. Another aspect of the invention relates to a system for layout and routing of integrated circuits. The system comprises a routing module that, when routing wires or features for alternating aperture phase shift masks, considers routes essentially only in a primary wiring direction, and blocks sufficient free space between the end of a first feature and the beginning of a second feature to avoid phase conflicts between the first feature and the second feature. A further aspect of the invention relates to a computer-readable medium containing instructions that, when executed, cause a computer to produce a substantially phase-correct circuit routing for a plurality of features defined by alternating aperture phase shift masks. BRIEF DESCRIPTION OF DRAWINGS The invention will be described with respect to the following drawing figures, in which like numerals represent like views throughout the figures, and in which: FIG. 1 is a schematic view of an exemplary conventional bright field AltPSM layout; FIG. 2 is a schematic view of an exemplary conventional dark field AltPSM layout; FIG. 3A is a schematic view of a bright field AltPSM layout illustrating a “T” conflict created by the intersection of two orthogonal features; FIG. 3B is a schematic view of a bright field AltPSM layout similar to that of FIG. 3A, illustrating the avoidance of a “T” conflict using methods according to embodiments of the invention; FIG. 4A is a schematic view of a bright field AltPSM layout illustrating an “odd/even” conflict created by several nearby features, one of which changes direction; FIG. 4B is a schematic view of a bright field AltPSM layout similar to that of FIG. 4A illustrating the avoidance of an “odd/even” conflict using methods according to embodiments of the invention; FIG. 5A is a schematic view of a bright field AltPSM layout illustrating a “line end” conflict created by the end of one feature proximate to another feature; FIG. 5B is a schematic view of a bright field AltPSM layout illustrating the avoidance of a “line end” conflict using methods according to embodiments of the invention; FIG. 6A is a schematic view of a dark field AltPSM layout illustrating a “T” conflict; FIG. 6B is a schematic view of a dark field AltPSM layout illustrating the avoidance of a “T” conflict using methods according to embodiments of the invention; FIG. 7A is a schematic view of a dark field AltPSM layout illustrating an “odd/even” conflict; FIG. 7B is a schematic view of a dark field AltPSM layout illustrating the avoidance of an “odd/even” conflict using methods according to embodiments of the invention; FIG. 8 is a schematic view of a dark field AltPSM layout illustrating a phase correct even jog that may be used in methods according to embodiments of the invention; FIGS. 9A and 9B are schematic views of dark field AltPSM layouts illustrating phase correct odd jogs that may be used in embodiments of the invention; FIG. 10A is a schematic view of a dark field AltPSM layout illustrating phase correct phase shapes that terminate at pins according to embodiments of the invention; FIG. 10B is a schematic view of a dark field AltPSM layout illustrating phase correct phase shapes that terminate at pins according to embodiments of the invention; and FIG. 11 is a schematic flow diagram of a routing system according to embodiments of the invention. DETAILED DESCRIPTION In general, embodiments of the invention provide methods and systems for designing and laying out integrated circuits using AltPSM techniques. Methods and systems according to embodiments of the invention may be used with and embodied in automated programs that create wiring layouts and routes, as well as with manual layout and routing techniques. The use of phase shapes or design shapes having particular phases may create certain routing problems for wiring and other features in AltPSM layout and routing. The description below presents certain particular examples of these problems, along with design principles and alternative routing layouts for avoiding the problems in systems and methods according to embodiments of the invention, for both bright field and dark field AltPSM. FIG. 3A is a schematic view of a bright field AltPSM layout 50 illustrating a “T” conflict created by the intersection of orthogonal wires 52, 54, 62. Wires 54 and 62 run vertically (with respect to the coordinate system of the figure); feature 52 runs horizontally. Three phase shapes 56, 58, and 60 flank the three orthogonal wires 52, 54, 62. Phase shapes 56 and 58 are 180° out of phase with each other and will thus create the interference necessary to define wires properly. However, phase shape 60 is not 180° out of phase with both of the other phase shapes 56, 58; therefore, some portion of the orthogonal wires 52, 54, 62 will be malformed or unsharp because two mutually 180° out of phase shapes are not present to define each feature 52, 54, 62. The three points A, B, C in FIG. 3A, and the lines between them, illustrate the improper odd cycle (i.e., the phase pairings that improperly occur between the three phase shapes 56, 58, 60). In embodiments of the invention, the wiring on each metallization layer is designed to run in a primary wiring direction. Additionally, a layout grid having some uniform basic pitch, or spacing between features, is defined. As the term is used here, a “standardized” or “uniform” grid or basic pitch may refer to a grid with a uniform pitch or spacing in all directions or a uniform pitch in only a single direction. (However, for simplicity in description, embodiments of the invention will be described with respect to spacing grids that are uniform in all directions.) Typically, because of general integrated circuit design requirements, some or all of the wires or features on each metallization layer would be designated as “critical,” or those that will be fabricated with specified dimensions. In typical integrated circuit designs, “critical” wires or features are fabricated with the minimum possible dimensions or spacings, although this need not necessarily be the case. A wire or feature may be designated as “critical” for a number of reasons, all of which would be readily discerned by those of skill in the art. Typically, “critical” features are those that have at least one dimension equal to a single space on the grid (e.g., a feature width of one grid space). Features that are “non-critical” are typically those that have dimensions occupying more than one space on the grid (e.g., a feature width of two or more grid spaces). Two design principles according to embodiments of the invention may avoid conflicts such as that shown in FIG. 3A, given the circuit layout design practices described above. The first design principle is that wires and features that run in the primary wiring direction should be on a uniform pitch and may or may not be designated as “critical,” depending on the particular circuit. The second design principle is that wires running orthogonal to the primary wiring direction should be designated as “non-critical” and given larger dimensions (e.g., dimensions that would not require phase shapes or phase coloring). FIG. 3B is a schematic view of a bright field AltPSM layout 75 similar to that of FIG. 3A, illustrating the avoidance of the phase conflict shown in FIG. 3A by application of the two design principles described above. In the case of FIGS. 3A and 3B, the primary wiring direction is vertical (with respect to the coordinate system of those figures). In FIG. 3B, as in FIG. 3A, two wires 64, 66 run in the vertical direction. A third wire 68 runs orthogonally (i.e., horizontally) with respect to the other two wires 64, 66 to connect them. By the second of the two design principles described above, the orthogonal wire 68 is “non-critical,” has dimensions larger than the two vertical wires 64, 66, and does not require phase shapes. Properly paired phase shapes 70, 72, 74, 76 flank the two vertical wires 64, 66, respectively. (Points D, E, F, G and the lines between them illustrate proper pairings between the phase shapes 70, 72, 74, 76.) Note that by the first design principle described above, the two vertical wires 64, 66 may be of either “critical” or “non-critical” dimensions, although they are illustrated as being of “critical” dimensions in FIG. 3B. FIG. 4A is a schematic view of a bright-field AltPSM layout 100 illustrating an “odd-even” conflict. As shown, the AltPSM layout 100 includes three wires, 102, 104, 106. Top wire 102 turns downward approximately when the middle wire 104 terminates. (The change in direction of top wire 102 may also be referred to as a “jog,” and certain considerations relating to jogs in methods according to embodiments of the invention will be described below in more detail.) The bottom wire 106 continues straight through AltPSM layout 100. Phase shapes 108 and 110 flank the top wire 102, phase shapes 110 and 112 flank the middle wire 104, and phase shapes 112 and 114 flank the bottom wire 106. By the nature and general principles of AltPSM layout, the middle wire 104 should be flanked with phase shapes along its entire length. However, by another general principle of AltPSM layout, the phase shapes used for the top wire 102 should remain consistent along the entire length of the top wire 102. Therefore, a conflict arises because of phase shapes 110 and 112, as shown by points H, I, J, K and the lines between them. (Points H, I, and J define an “odd cycle.”) FIG. 4B is a schematic view of a bright field AltPSM layout 150 similar to that of FIG. 4A, illustrating the avoidance of an “odd-even” conflict using the design principles described above. AltPSM layout 150 also includes three wires: a top wire 152, a middle wire 154, and a bottom wire 156. The three wires 152, 154, 156 have generally the same configuration as the corresponding wires 102, 104, 106 of FIG. 4A. However, in FIG. 4B, by the second of the two design principles described above, the orthogonal section 158 of the top wire 152 has been designated as “non-critical” and has been widened accordingly (in this case, to double the “critical” width). Because the orthogonal section 158 has been widened and is “non-critical,” there is no need for flanking phase shapes, and the conflict is thus resolved. Phase shapes 160 and 162 flank the upper portion of top wire 152, while phase shapes 164 and 170 flank the bottom portion of top wire 152. (Phase shapes 162 and 164 have the same phase, which is 180° out of phase with that of phase shape 160. The phase of phase shape 170 is the same as that of phase shape 160.) Phase shapes 164 and 166 flank the middle wire 154 and are mutually 180° out of phase. Phase shapes 166 and 170 have the same phase and flank the top of bottom wire 156, while phase shape 168 flanks the bottom of bottom wire 156. (Points L, M, N, O, P and the lines between them illustrate the corrected phase pairings.) FIG. 5A is a schematic view of an AltPSM layout 200 illustrating a “line end” conflict created by the end of one feature proximate to another. A horizontal wire 202 and a vertical wire 204 are shown in FIG. 5A. Horizontal wire 202 is flanked by phase shapes 206 and 208; vertical wire 204 is flanked by phase shapes 210 and 212. Because of the proximity of the horizontal 202 and vertical 204 wires, a phase conflict arises between phase shapes 206, 208 and 210, as shown by points R, S, T, U and the lines between them. FIG. 5B is a schematic view of an AltPSM layout 250 illustrating the avoidance of a “line end” conflict. As shown in FIG. 5B, AltPSM layout 250 includes a horizontal wire 252 and a vertical wire 254. By the second of the two deprinciples sign described above, assuming the primary wiring direction on the metallization layer is horizontal, the vertical wire 254 has been made “non-critical” and, accordingly, has been given a greater width so that flanking phase shapes are not required. Horizontal wire 252 is flanked by phase shapes 256 and 258, which are mutually 180° out of phase. (The correctness of the phase pairing is shown by points V and X and the line between them.) For dark-field wire routing and AltPSM phase shapes, three specific design principles may apply in methods according to embodiments of the invention. First, all wiring and other features in a dark field AltPSM routing layout should run in the primary wiring direction. In the case of dark field AltPSM, wires and other features orthogonal to the primary wiring direction should generally be avoided. Second, where a wire or feature ends, additional space should be inserted beyond the edge of the wire or feature, for example, doubling the free space between the end of one wire or feature and the beginning of another. A third design principle, which flows from the second principle, is that pins should not be aligned in the primary wiring direction at minimum spacing, because two such pins aligned at minimum spacing are likely to cause violations of the second design principle. (Pins and their layout in methods according to embodiments of the invention will be described below in more detail.) FIG. 6A is a schematic view of a portion of a dark field AltPSM layout, generally indicated at 300, illustrating a “T” conflict. In layout 300, three wires 302, 304, 306 are given phases. Wire 302 runs horizontally through layout 300. Wire 304, immediately below wire 302, terminates mid-way through layout 300, and wire 306 begins a short distance after the end of phase shape 304. Wires 302 and 306 are mutually 180° out of phase with each other, and will thus properly define wires; however, phase shape 304 is not 180° out of phase with either of wires 302 or 306. Therefore, wire 304 will not properly define the spaces between the wires 302, 304, 306 in combination with the other two wires 302, 306. (The odd cycle is shown by points Y, Z, and AA, and the lines between them.) In general, the need for wires 302, 304, 306 of three different phases is created by the spacing between the end of wire 304 and the beginning of wire 306. FIG. 6B is a schematic view of a dark field AltPSM layout 350, illustrating the avoidance of a “T” conflict using methods according to embodiments of the invention. Layout 350 includes three wires 352, 354, 356 with phases. Similarly to layout 300, wire 352 runs horizontally through layout 350. Wire 354, below wire 352, terminates approximately mid-way through layout 350, and wire 356 begins a short distance after the end of wire 304. However, by the second design principle for dark field AltPSM, in layout 350, extra space has been inserted between the respective ends of wires 354 and 356, approximately doubling the amount of space between them. The particular amount of space may vary, but would generally be enough space to render the space between the features “non-critical” in dimension. Accordingly, the conflict is eliminated; wires 354 and 356 are mutually 180° out of phase with wire 352. The proper phase pairings are shown by points BB, CC, and DD and the lines between them. FIG. 7A is a schematic view of a dark field AltPSM layout 400, illustrating an “odd-even” conflict. Layout 400 has three wires 402, 404, 406 with phases. Top wire 402 extends the entire length of layout 400 but includes a jog and changes direction downward approximately mid-way through layout 400 before changing direction again and resuming its horizontal course. Wire 404 extends to a point approximately mid-way through layout 400 and terminates. Wire 406 extends horizontally along the entire length of layout 400. The jog of wire 402 creates a phase conflict between wire 404 and the other two wires 402, 406. The phase conflict is shown by points EE, FF, and GG and the lines between them. FIG. 7B is a schematic view of a dark field AltPSM layout 450, illustrating the avoidance of an “odd-even” conflict using methods according to embodiments of the invention. Layout 450 includes four wires 452, 454, 456, 458 with phases. Wires 452 and 454 traverse essentially the same route as wire 402 of layout 400. However, neither of wires 452 or 454 includes a jog; both wires 452, 454 extend horizontally. By the first design principle for dark field AltPSM routing and layout, the sections of wiring orthogonal to the primary wiring direction (the primary wiring direction being horizontal in the case of FIG. 7B) have been moved to another metallization layer. Wires 452 and 454 are connected at respective ends to a structure 460 that is in electrical communication with another metallization layer on which vertical is the primary wiring direction. The correct phase pairings are shown by points HH, II, JJ, and KK and the lines between them. As was described above particularly with respect to wire 102 and wire 402, jogs or changes in direction of features may cause routing and phase conflicts among AltPSM phase shapes and phase-colored features. However, it should be understood that not all jogs will cause phase conflicts. In particular, if an AltPSM layout is performed on a standardized pitch or grid, then jogs that run for an even number of grid spaces may not cause phase or routing conflicts if proper spacing is maintained between the jogged portion of the wire and other wires it passes (applying the second principle of dark field AltPSM routing and layout between wire ends and the jogged wire section). FIG. 8 is a schematic view of a dark field AltPSM layout 500. Layout 500 includes phase-colored wires 502 and 504. Below wire 504 in layout 500 is wire 506, which begins on the upper left of layout 500 and jogs downward approximately mid-way through layout 500 to terminate on the lower right of layout 500. The phase of wires 502 and 506 are properly mutually 180° out of phase, as are wires 504 and 506. In addition to wires 502, 504, and 506, a number of smaller features populate layout 500. In particular, wires 508 and 510, which are properly mutually 180° out of phase, are to the left of jog 507 in wire 506. Wires 512 and 514, which are properly mutually 180° out of phase, are to the right of jog 507 in wire 506. In addition to the wires, FIG. 8 includes four rectangular indicators 516 for illustrative purposes (i.e., the indicators 516 are not features in the layout). The indicators 516 indicate the pitch or grid size on which layout 500 is created. Additionally, the indicators 516 are positioned at points that should be left empty of features in order for no phase conflicts to arise. As can be seen by comparison to the indicators 516, the jog 507 in phase shape 506 extends for an even number of grid spaces, which, in general, prevents phase conflicts. Wires and phase shapes having more than one jog may avoid conflict in methods according to embodiments of the invention by following the general principle illustrated in FIG. 8 and extending the jog for an even number of grid spaces. In some cases, wires or phase shapes may also jog for an odd number of grid spaces. FIGS. 9A and 9B are schematic views of dark field AltPSM layouts 550 and 580, respectively, which illustrate phase correct layouts with wires having jogs extending for an odd number of grid spaces. Wire 552 has a central, U-shaped jog 553. Smaller wires 554 and 556, which are correctly mutually 180° degrees out of phase, are located below wire 552 and to the left of jog 553. Wire 554 is also 180° out of phase with wire 552. Smaller wires 558 and 560, which are correctly mutually 180° degrees out of phase, are located below wire 552 and to the right of jog 553. Wire 558 is also 180° out of phase with wire 552. Jog 553 extends downward an odd number of grid spaces. Therefore, because of jog 553 in wire 552, area 562 should be left free of wires or other features in order to prevent phase conflicts. Dark field AltPSM layout 580 of FIG. 9B illustrates a similar situation. Wire 582 has a downward jog 583, such that it begins in the upper left of layout 580 and terminates toward the lower right. Jog 583 extends an odd number of grid spaces. Shorter wires 584 and 586 extend below the upper left portion of wire 582 and are correctly mutually 180° out of phase with each other. Wire 584 is correctly 180° out of phase with wire 582. Because of the odd jog 583, areas 588 and 590 should be left free of wires or other features in order to prevent phase conflicts. Other situations can arise in dark field AltPSM when wires terminate at pins. FIG. 10A is a schematic view of a dark field AltPSM layout 600 illustrating one phase-correct way of terminating wires at pins. As shown in FIG. 9A, two phase-colored wires 604 and 610, which are not correctly mutually out of phase, terminate at respective pins 606 and 612. In order to avoid phase conflicts, a third wire 602 with a phase that is properly 180° out of phase with both wires 604 and 610, jogs in and terminates at a pin 608 that is interposed between pins 606 and 612. This arrangement represents a special case, because of the jog of third wire 602. As an alternative to layout 600, FIG. 10B is a schematic view of a dark field AltPSM layout 650 which illustrates two horizontal wires 652 and 658 that terminate at respective pins 654 and 656. The wires 652, 658 are properly mutually 180° out of phase, preventing a phase conflict. The AltPSM layouts described above with respect to FIGS. 3A-10B illustrate representative routing and phase conflicts in bright field and dark field AltPSM, respectively, and exemplary methods of resolving those conflicts using methods and systems according to embodiments of the invention. It should be understood that the examples presented above may not be the only types of conflicts that may arise in AltPSM layout. However, certain types of more complex conflicts may be analyzed as being combinations of the basic types of conflicts that were described above. Some additional difficulties can arise in dark field AltPSM layout and routing. Part of the additional difficulty with dark field AltPSM layout arises because phase shapes flanking each feature are not applied in dark field AltPSM; instead, particular phases are directly applied to existing wires and other design features. Therefore, errors in phase coloring and in the phases of adjacent shapes or features may not be readily apparent. Additionally, because wiring (typically defined with dark field AltPSM) usually runs for longer distances than the polysilicon gates and other features that are typically defined with bright field AltPSM, the potential for phase conflicts in dark field AltPSM may be greater than that in bright field AltPSM. Work by the inventor has demonstrated that traditional wire routing methods and programs often violate the design principles set forth above and produce improper dark field AltPSM phase colorings and layouts. For example, TABLE 1 sets forth the average number of violations of each type found on each of three metallization layers (M1-M3) for macros on two microprocessors. The three types of violations are classified as odd cycles (examples of which were illustrated above), routing restriction violations (e.g., of the design principles set forth above), and illegal pin placements. TABLE 1 Average Violations P1-3 P4 P5-8 M1 Odd Cycles 245.3 786 6.0 M1 Routing Restriction Violations 749.7 4008 9.0 M2 Odd Cycles 107.3 0 22.5 M2 Routing Restriction Violations 157 13 42.0 M3 Odd Cycles n/a n/a 0.75 M3 Routing Restriction Violations n/a n/a 2.5 Illegal Pins 121.3 1450 46.5 Of the eight cases shown in TABLE 1, the layout and routing for P4 was performed largely by hand. In the case of P4, nearly 15% of the pins were illegally located, and 2495 shapes contained wrong-way wiring (i.e., wiring that is not in the primary wiring direction). Routing programs according to embodiments of the invention may be implemented in a variety of different programming languages, including interpreted scripting and macro languages and compiled languages, and on a variety of different platforms. For example, routing programs according to embodiments of the invention may be implemented in compiled languages like C and C++, as well as in other languages such as Java and J++on platforms including general purpose computers, special purpose computers, and any other device capable of executing a routing program. Although the term “implemented” is used, it should be understood that the process of creating a routing program according to embodiments of the invention may include a process of modifying an existing routing program to route so as to avoid the types of phase conflicts identified above with respect to FIGS. 3A-10B. Additionally, routing programs may use any known optimization and/or search algorithms to determine proper routing. FIG. 11 is a schematic flow diagram illustrating the general tasks involved in a routing method 700 according to embodiments of the invention. Routing method 700 may be embodied in a routing system according to embodiments of the invention, and generally follows the AltPSM design principles set forth above with respect to bright and dark AltPSM layout. Routing method 700 begins at S702 and control passes to S704. At S704, the basic information provided to the routing system is initialized, including the list of nets, the list of pins, and the routing cost information used to determine the best routes. Once initialization is complete in S704, method 700 continues with S706. In S706S710, method 700 verifies the placement of each pin. Control of method 700 is returned to S706 from S710 for each pin, so that the placement of each can be verified. In the context of embodiments of the present invention, the pin placement verification of S706S710 may include checking for the pin spacing problems that were noted above, as well as a number of related tasks that will be explained below in more detail. Once pin placement verification is complete in S710 (S710:NO), method 700 proceeds with S712, in which a particular net is selected. After a net is selected, target pins are selected in S714. Method 700 then determines a route between the target pins in S716. The routing performed in S716 may be constrained so as to produce phase-correct routing by applying the design principles set forth above. For example, when searching for a route, method 700 may consider only grid spaces that run in the primary wiring direction for dark field AltPSM layout (or, alternatively, if a jog is required, method 700 may consider jogs only of lengths that will avoid phase conflicts). Additionally, in bright field AltPSM layout, method 700 may check for the existence of extra free space for wires that run orthogonal to the primary wiring direction. The routing task of S716 may be limited to a maximum number of routing attempts, so that method 700 does not become “stuck” if no routing solution exists for a set of pins. If a route is found between two pins, method 700 continues with S718, in which method 700 retraces the route to add design shapes (i.e., the actual shapes of the wires or features that connect the two pins). In the process of retracing, method 700 may also observe the design principles noted above, for example, by marking a space beyond the end of a feature as “blocked” in dark field AltPSM layout, so as to prevent the phase conflict shown in FIG. 6A. Additionally, method 700 may set the width of wires running orthogonal to the primary wiring direction as double the usual width in bright field AltPSM layout. After retracing is complete in S718, method 700 continues with S720, a decision task. In S720, if there are other pins in the selected net to be routed (S720:YES), control returns to S714. If there are no pins remaining in the selected net to be routed (S720:NO), control passes to S722, another decision task. In S722, if there are other nets to be routed (S722:YES), control returns to S712. If there are no nets remaining to be routed (S722:NO), then control passes to S724, where method 700 terminates and returns. Thus, the routing tasks described above are performed for each pin in each net. As those of skill in the art will realize, routing methods and systems may perform additional tasks, including pin-to-net routing. The tasks described with respect to method 700 are not intended to be an exclusive list. As one particular example of a layout and routing system according to embodiments of the invention, a phase-correct interactive layout system according to embodiments of the invention was implemented in C++ by modifying an existing interactive layout system. The existing interactive layout system used a gridded multilayer router with a best first search algorithm. One of the differences between the original interactive layout system and the phase-correct layout system was in the types of wiring moves which the system was permitted to explore. The design principles described above for bright and dark field AltPSM were implemented as limitations in the search stage of the algorithm. During the retrace stage, blockages on extra grids were inserted. For a bright field wire which is routed perpendicular to the primary direction, a double width wire was inserted and two side-by-side grid points were blocked at each point along the wire's length. For a dark field wire, a blocked grid point was placed on the grid which lay one grid point beyond each end of a wire in the primary routing direction. In general, the exemplary layout system followed the set of tasks described above with respect to method 700. Pseudocode for the exemplary layout system follows: For Each Net Select an Unrouted Pin. If two pins have already been connected, only allow pin to net connections (not pin to pin). Path Trace←empty Fronts←φ Lowest Cost Grid infinity Add the pin location to the heap of fronts, with cost equal to zero While front size ≠0 and no path exists and iterations<maximum iterations Front←top of Fronts heap (lowest cost entry) For each possible neighbor point (there are 6: up, down, left, right, up level, down level) For Dark Field, only neighbors in the primary wiring direction are considered Does the Neighbor point exist and is this neighbor point one of the following? a. Open: Routing Grid [neighbor]=empty b. A target (i.e., a pin for this net): Routing Grid [neighbor]=pin on this net c. For Dark Field: additional grid space is available if we are changing levels Move cost←front cost+cost to move in this direction If Move cost<Lowest Cost [neighbor point] For Bright field levels, check for free neighbor grids for wrong-way wires Accept a move if an additional free grid is available Add the neighbor grid location to the Fronts heap Path Trace[neighbor]←direction we came from If path was found to a target: Retrace from the target back to the source, adding design shapes Positions←Target Location State 0: Position←Direction pointed to by Path Trace[Position] State←1 State 1: Start of a line segment If not primary direction and bright field: line with←2×level width If dark field: Mark a PSM Blockage beyond the line endpoint Else line width←level width Starting Point←Position Routing Grid [Position]←used If not primary direction and bright field: Routing Grid[Position's neighbor]←used Owner[Position]←this net Position←Direction pointed to by Path Trace[Position] If New Position is in same direction as previous position (still in a line): State←2 Else State←3 State 2: Point along a line segment Routing Grid [Position]←used If not primary direction and bright field: Routing Grid[Position's neighbor]←used If dark field: Mark a PSM Blockage beyond the line endpoint Owner[previous point]←this net Position←Direction pointed to by Path Trace[Position] If New Position is in same direction as previous position (still in a line): State←2 Else State←3 State 3: End of a line segment If Starting Point and Current Position are equal, create a rectangle in layout Else Create a line in the layout: From Starting Point to Current Position With line width State←0//Do not get a new point Release the Fronts heap The exemplary layout system functioned with the aid of certain assumptions, which were as follows: 1. Wires may be placed on adjacent grid points without violating minimum spacing requirements. 2. Wires may end on adjacent grids without violating spacing requirements. 3. Wires may be placed on the grids nearest the boundaries without considering what lies beyond the boundaries, because it is assumed that a “guard ring” of empty space (e.g., at least one grid point) exists around the boundary. 4. Shapes (for bright field AltPSM layout) and spaces (for dark field AltPSM layout) that have minimum width are critical. 5. Shapes (for bright field AltPSM layout) and spaces (for dark field AltPSM layout) that are twice the minimum width (e.g., two grid spaces) are non-critical. Of course, not all of the above assumptions need be made in layout and routing systems according to embodiments of the invention. In particular, circuit elements beyond the boundaries of a particular layout may also be designed for phase-correct routing, so as to eliminate the need for free space. Additionally, wire jogs may be included in dark field AltPSM layers as was described above. The exemplary phase correct router implemented four types of layers. A first type of layer included no phase restrictions and allowed wires to be routed vertically and horizontally as desired. A second type of layer was a bright field AltPSM phase correct layer. On the bright field AltPSM phase correct layer, wires or features orthogonal to the primary wiring direction were routed at twice the standard width and blocked two adjacent grid points. A third type of layer was the dark field AltPSM phase correct layer. On the dark field AltPSM phase correct layer, wires were only allowed to run in the primary wiring direction, ends of wires were provided with an extra grid point of adjacent free space, and each pin was checked for legality. A fourth type of layer was similar to the dark field AltPSM phase correct layer, but without additional blocked grid points, and was used to test certain aspects of switchbox routing. In general, the exemplary routing and layout system described above in pseudocode performed well, leaving very few nets and pins unrouted. Manual changes to the order of nets and pins allowed the system to complete the routing of all pins and nets. Conventional rip-up and re-route algorithms may be added to the exemplary system presented above, as they may allow the exemplary routing and layout system, as well as other systems according to embodiments of the invention, to complete the routing of all pins and nets. Although the invention has been described with respect to certain exemplary embodiments, modifications and variations may be made within the scope of the appended claims.

<SOH> BACKGROUND OF INVENTION <EOH>1. Field of the Invention The invention relates to methods and systems for design, layout, and routing of integrated circuits using alternating aperture phase shift masks. 2. Description of Related Art The features of small integrated circuit semiconductor devices, such as microprocessors, are usually defined by using lithographic techniques on a semiconductor wafer. A typical lithographic mask for semiconductor photolithography processes is a sheet of quartz onto which a layer of chrome or another opaque material is deposited in patterns that define the shapes which are to be reproduced lithographically on the semiconductor wafer. As better technologies have allowed the features of a semiconductor device to become smaller and smaller, feature size has begun to approach the theoretical minimum size that can be faithfully reproduced by conventional lithographic techniques. Therefore, as feature sizes have become smaller and smaller, engineers have turned to a number of Resolution Enhancement Techniques (RET) that improve the resolution of the conventional processes. One RET is a technique known as Alternating Aperture Phase Shift Masks (AltPSM). In general, AltPSM makes use of the constructive and destructive interference of light to sharpen the edges and increase the resolution of lithographically reproduced features. Specifically, some portions of AltPSM masks are etched so as to be thinner, or have additional layers of transparent material deposited on them so as to be thicker. Changing the depth of material through which light passes during lithography alters the phase of the light. By selecting and controlling the depth (i.e., thickness) of the mask, an AltPSM mask can have areas in which the light passing through the mask is 180° out of phase with respect to the other areas of the same mask. When light that is 180° out of phase meets at the wafer, either constructive interference or destructive interference may occur, and the interfering light defines the pattern to which the (usually photoresist-covered) wafer is actually exposed. Typically, light of a particular wavelength (e.g., currently 193 nanometers (nm)) is used in semiconductor lithography. Resolution Enhancement Techniques such as AltPSM may be used to print features smaller than the wavelength of the light. When using AltPSM techniques in integrated circuit design and layout, features that approach the minimum size may be defined, at least in part, by shapes having the phases necessary to cause interference and create the desired feature. Two primary types of AltPSM are in use: bright field and dark field. The two techniques are complements of one another. In bright field AltPSM, phase shifting shapes are added to the layout to sharpen the focus of the design features. In dark field AltPSM, phases are added to the design features themselves to define and sharpen the spaces between the features. For example, FIG. 1 is a depiction of an exemplary phase-correct bright field AltPSM layout 10 . The actual shape of the feature 12 is flanked on each side by a phase shape 14 , 16 . The two phase shapes 14 , 16 have phases that are 180° out of phase, so that interference of light will define the desired feature 12 . FIG. 2 is a depiction of an exemplary phase-correct dark field AltPSM layout 20 . In the dark field layout 20 , three wires 22 , 24 , 26 are given particular phases; the uppermost and lowermost phase wires 22 , 26 in FIG. 2 have the same phase, and the center wire 24 has a phase 180° out of phase with the other two wires 22 , 26 ; therefore interference between the center wire 24 and the top and bottom wires 22 , 26 will define and sharpen the spaces between the wires. Typically, bright field AltPSM is used for polysilicon layers and dark field AltPSM is used for metal layers (e.g., wiring layers). The overall process of determining the location and phase of AltPSM phase shapes is sometimes referred to as “phase coloring,” particularly in the case of dark field AltPSM, in which phases are added to existing shapes or features. AltPSM layouts and routings may be determined for an entire integrated circuit together, or for smaller individual portions of the circuit, for example, between a certain group of standard or “book” elements in one portion of the integrated circuit.

<SOH> SUMMARY OF INVENTION <EOH>One aspect of the invention relates to a method for laying out features for alternating aperture phase shift masks. The method comprises defining features on a grid of a uniform basic pitch. The method also comprises orienting the features such that those of the features defined, at least in part, by phase shifting shapes are oriented along a primary direction, and spacing two features terminating adjacent one another such that the two features have space between them sufficient to prevent phase conflicts if both of the two features are defined, at least in part, by phase shifting shapes. Another aspect of the invention relates to a system for layout and routing of integrated circuits. The system comprises a routing module that, when routing wires or features for alternating aperture phase shift masks, considers routes essentially only in a primary wiring direction, and blocks sufficient free space between the end of a first feature and the beginning of a second feature to avoid phase conflicts between the first feature and the second feature. A further aspect of the invention relates to a computer-readable medium containing instructions that, when executed, cause a computer to produce a substantially phase-correct circuit routing for a plurality of features defined by alternating aperture phase shift masks.

20040623

20090106

20051229

96806.0

ROSSOSHEK, YELENA

METHODS AND SYSTEMS FOR LAYOUT AND ROUTING USING ALTERNATING APERTURE PHASE SHIFT MASKS

UNDISCOUNTED

ACCEPTED

ACCEPTED

INFRARED SENSOR PACKAGE

An optical sensor package with a substrate that supports a membrane carrying an optical sensor and through which radiation passes to impinge the sensor. The substrate has a first surface in which a cavity is defined, a second surface opposite the first surface, and a wall between the cavity and the second surface. The optical sensor is supported on the membrane, which is bonded to the substrate and spans the cavity in the substrate. A window is defined at the second surface of the substrate for enabling infrared radiation to pass through the wall of the substrate to the optical sensor.

1. An optical sensor package comprising: a substrate having a first surface in which a cavity is defined, a second surface opposite the first surface, and a wall between the cavity and the second surface, at least a portion of the substrate being formed of silicon; a membrane bonded to the substrate and spanning the cavity in the substrate; an optical sensing element on the membrane; and a window at the second surface for enabling infrared radiation to pass through the wall of the substrate to the optical sensing element, the wall allowing only radiation of wavelengths longer than 1.1 micrometers to pass therethrough to the optical sensing element. 2. The optical sensor package according to claim 1, wherein the optical sensing element is a thermopile. 3. The optical sensor package according to claim 1, further comprising integrated circuitry on the substrate, the integrated circuitry performing logic functions and signal processing for the optical sensing element. 4. The optical sensor package according to claim 3, wherein the integrated circuitry is between the membrane and the substrate. 5. The optical sensor package according to claim 1, wherein the substrate and the wall are defined by a monocrystallographic silicon chip. 6. The optical sensor package according to claim 1, further comprising a filtering material at the second surface of the substrate. 7. The optical sensor package according to claim 6, wherein the filtering material is implanted in the second surface of the substrate. 8. The optical sensor package according to claim 6, wherein the filtering material is epitaxially grown on the second surface of the substrate. 9. The optical sensor package according to claim 6, wherein the filtering material is a first chip that constitutes a first portion of the substrate, the cavity is defined in a silicon chip that constitutes a second portion of the substrate, and the first and silicon chips are bonded together to form the substrate. 10. The optical sensor package according to claim 6, wherein the filtering material is chosen from the group consisting of germanium, PbS, InAs, and PbTe. 11. The optical sensor package according to claim 1, further comprising an antireflection coating on the second surface of the substrate, the antireflection coating minimizing reflection of infrared radiation by the substrate. 12. The optical sensor package according to claim 11, wherein the window comprises a coating on the antireflection coating, the coating being substantially opaque to infrared radiation and having an opening aligned with the wall of the substrate and the optical sensing element on the membrane. 13. The optical sensor package according to claim 1, further comprising a capping chip secured to the substrate and enclosing the membrane. 14. An infrared sensor package comprising: a substrate having a first surface in which a cavity is defined, a second surface opposite the first surface, and a wall defined by and between the cavity and the second surface, at least a portion of the substrate being formed of silicon; a membrane bonded to the substrate and spanning the cavity in the substrate; a thermopile sensing element on the membrane; and integrated circuitry on the substrate, the integrated circuitry performing logic functions and signal processing for the thermopile sensing element; a window at the second surface for enabling infrared radiation to pass through the wall of the substrate to the thermopile sensing element. 15. The infrared sensor package according to claim 14, wherein the wall is defined by the silicon portion of the substrate. 16. The infrared sensor package according to claim 14, wherein the substrate and the wall are defined by a monocrystallographic silicon chip. 17. The infrared sensor package according to claim 14, further comprising a filtering material implanted in the second surface of the substrate. 18. The infrared sensor package according to claim 14, further comprising a filtering material epitaxially grown on the second surface of the substrate. 19. The infrared sensor package according to claim 14, wherein the substrate comprises a first chip of a filtering material bonded to a silicon chip in which the cavity is defined. 20. The infrared sensor package according to claim 14, further comprising a capping chip secured to the substrate and defining a cavity that encloses the membrane.

CROSS REFERENCE TO RELATED APPLICATIONS This application claims the benefit of the U.S. Provisional Application No. 60/489,726, filed Jul. 24, 2003. BACKGROUND OF INVENTION 1. Field of the Invention The present invention generally relates to packages for containing electronic devices, and more particularly to a package having a infrared sensor mounted to a silicon base through which infrared radiation passes before impinging the sensor. 2. Description of the Related Art Infrared (IR) sensors have been used to measure the temperature of thermal sources, such as hot materials, humans, etc. To accurately detect heat radiated from a target, interference from ambient light, particularly visible light, should be filtered out. This can be done by adding a filter in front of the IR sensor. For example, in commonly-assigned U.S. patent application Ser. No. 10/065,446 to Logsdon et al., a chip formed of silicon—which allows only wavelengths longer than about 1.1 φm to pass through—is individually mounted to a chip carrier on which an infrared sensor is mounted so that the silicon chip is between the sensor and the target being sensed. In the automotive applications, an IR sensor package equipped with such a silicon “window” allows a targeted subject, such as the driver or passengers of a car, to be monitored with minimum background interferences. SUMMARY OF INVENTION The present invention is directed to an optical sensor package in which a substrate supports a membrane carrying an optical sensor, and radiation passes through the substrate to impinge the sensor. Generally, the optical sensor package includes a substrate, at least a portion of which is formed of silicon. The substrate has a first surface in which a cavity is defined, a second surface opposite the first surface, and a wall between the cavity and the second surface. An optical sensing element is supported on a membrane bonded to the substrate and spanning the cavity in the substrate. A window is defined at the second surface of the substrate for enabling infrared radiation to pass through the wall of the substrate to the optical sensing element. The wall preferably has a bandgap of about 1.1 eV so as to absorb impinging radiation with wavelengths shorter than 1.1 micrometers, such that only radiation of wavelengths longer than 1.1 micrometers pass therethrough to the optical sensing element. From the above, it can be seen that a significant advantage of the invention is that the filter required for the sensor to be active only in the desired optical range is an integral part of the sensor structure. Other objects and advantages of this invention will be better appreciated from the following detailed description. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a cross-sectional view of an infrared sensor package in accordance with a first embodiment of this invention. FIGS. 2 and 3 show second and third embodiments of infrared sensor packages of this invention, wherein the backside of the silicon chip is provided with a filtering layer. FIG. 4 shows a fourth embodiment of an infrared sensor package of this invention, wherein the sensing elements are enclosed for protection from the surrounding environment. DETAILED DESCRIPTION The present invention provides an optical sensor package that employs a silicon-containing substrate as the supporting material for an IR sensor, which is preferably made by standard integrated circuit (IC) fabrication processes. A preferred sensor employs a thermopile as the IR sensor, such as the thermopiles disclosed in commonly-assigned U.S. patent application Ser. Nos. 10/065,447 and 10/065,448, the contents of which relating to thermopile construction are incorporated herein by reference. In addition, a suitable thermocouple structure for the thermopile is disclosed in commonly-assigned U.S. patent application Ser. No. ______ {Attorney Docket No. DP300915} to Jiang et al., the contents of which relating to thermocouple construction are incorporated herein by reference. According to the present invention, the substrate is configured to define a wall that serves as a filter to filter out visible light, allowing only infrared wavelengths of interest to reach the IR sensor. According to a preferred aspect of the invention, integrated circuitry for performing logic functions and signal processing required for the IR sensor can also be fabricated on or in the substrate. FIG. 1 is a cross-sectional view of an IR sensor package 10 in accordance with a first embodiment of the invention. The package 10 comprises a silicon substrate 12 in which a cavity 14 has been formed (e.g., etched), a multilayer membrane 16 bonded to the substrate 12 and enclosing the cavity 14, and a thermopile sensor 18 formed in a layer 20 of the membrane 16. Standard IC processes and micromachining techniques can be used to fabricate the sensor 18, including its structure and elements, on the membrane 16. One or more layers 22 of infrared absorbing and reflecting materials are shown as being formed on the membrane 16, thereby defining the outer surface of the membrane 16 to enhance infrared absorption and heat generation within the sensor 18. Suitable materials for the infrared absorbing and reflecting layers 22 include oxynitride, tetra-ethyl-ortho-silicate (TEOS) based oxides, low-temperature deposited oxides, and aluminum. The membrane 16 is bonded to the silicon substrate 12, which is preferably a monocrystallographic silicon chip. According to a preferred aspect of the invention, the package 10 is one of any number of packages that are micromachined and assembled at wafer-level and subsequently singulated into individual packages. Integrated circuitry 32 for performing logic functions and signal processing required for the thermopile sensor 18 is represented as being fabricated in the silicon substrate 12, such as located in the surface to which the membrane 16 is bonded. A wall 24 is defined by and between the cavity 14 and the backside surface of the substrate 12, and serves as a silicon window through which infrared radiation is permitted to pass to impinge the sensor 18 while filtering out undesired radiation. For this purpose, the backside surface of the substrate 12 has an antireflection coating 26, a portion of which is exposed within an opening 28 formed in an outer coating 30 to define the window region of the wall 24. The antireflection coating 26 minimizes the amount of infrared radiation reflected by the silicon substrate 12. Suitable materials for the antireflection coating 26 include a single layer of silicon nitride, organic layers, and other custom composite layers of appropriate materials at appropriate thicknesses to meet the required radiation spectrum sensing regime. The outer coating 30 on the substrate 12 is preferable opaque to the desired range of infrared radiation wavelengths, so that radiation of the desired wavelengths impinges the location on the membrane 16 corresponding to the location of the thermopile sensor 18, but radiation of other wavelengths are otherwise reflected to minimize thermal energy absorption by the sensor package 10. In view of the package configuration shown in FIG. 1, use of the sensor package 10 involves facing the backside of the silicon substrate 12 toward the intended target, such as the driver or passengers of a vehicle, so that infrared radiation passes through the silicon wall 24 of the substrate 12 to the sensing elements of the sensor 18 on the membrane 16. In this manner, visible light with wavelengths shorter than about 1.1 φm is filtered out by the silicon wall 24 before reaching the sensor 18. FIG. 2 shows an IR sensor package 40 similar to that of FIG. 1 (with the same reference numbers used to identify essentially the same features), but with a filter material 42 implanted and driven-in or epitaxially grown on the backside of the substrate 12 to provide a filtering layer. Depending on the filter material 42, different wavelengths of light can be filtered. Candidate materials include germanium (Ge), PbS, InAs, and PbTe, which allow only wavelengths longer than about 1.88, 3.02, 3.44 and 4.0 φm, respectively, to pass through the window 24 to the sensor 18. FIG. 3 shows a package 50 that is a variation of FIG. 2, in which filtering is achieved with a filter chip 54 that has been bonded to a silicon chip 52 to form the substrate 12. The chip 52 is represented as having been etched from backside to frontside (opposite that of FIGS. 1 and 2), such that the cavity 14 extends completely through the chip 52. The filter chip 54 can be, for example, a silicon or germanium chip bonded to the silicon chip 52. In this embodiment, wafer-level packaging of the additional filter material, as opposed to chip-level packaging, has the ability of lowering manufacture costs. FIG. 4 shows another variation of FIG. 2, in which a triple stack of wafers is used to form a package 60 that encloses the membrane 16, thereby protecting the membrane 16 and its thermopile sensor 18 from the surrounding environment. The package 60 is represented as having a third chip 62 bonded to the membrane 16, with a cavity 64 defined in the chip 62 so as to protectively enclose the membrane 16. Suitable materials for the chip 62 include silicon, the use of which permits the package 60 to be formed by silicon-to-silicon wafer bonding techniques. While the invention has been described in terms of a preferred embodiment, it is apparent that other forms could be adopted by one skilled in the art. Accordingly, the scope of the invention is to be limited only by the following claims.

<SOH> BACKGROUND OF INVENTION <EOH>1. Field of the Invention The present invention generally relates to packages for containing electronic devices, and more particularly to a package having a infrared sensor mounted to a silicon base through which infrared radiation passes before impinging the sensor. 2. Description of the Related Art Infrared (IR) sensors have been used to measure the temperature of thermal sources, such as hot materials, humans, etc. To accurately detect heat radiated from a target, interference from ambient light, particularly visible light, should be filtered out. This can be done by adding a filter in front of the IR sensor. For example, in commonly-assigned U.S. patent application Ser. No. 10/065,446 to Logsdon et al., a chip formed of silicon—which allows only wavelengths longer than about 1.1 φm to pass through—is individually mounted to a chip carrier on which an infrared sensor is mounted so that the silicon chip is between the sensor and the target being sensed. In the automotive applications, an IR sensor package equipped with such a silicon “window” allows a targeted subject, such as the driver or passengers of a car, to be monitored with minimum background interferences.

<SOH> SUMMARY OF INVENTION <EOH>The present invention is directed to an optical sensor package in which a substrate supports a membrane carrying an optical sensor, and radiation passes through the substrate to impinge the sensor. Generally, the optical sensor package includes a substrate, at least a portion of which is formed of silicon. The substrate has a first surface in which a cavity is defined, a second surface opposite the first surface, and a wall between the cavity and the second surface. An optical sensing element is supported on a membrane bonded to the substrate and spanning the cavity in the substrate. A window is defined at the second surface of the substrate for enabling infrared radiation to pass through the wall of the substrate to the optical sensing element. The wall preferably has a bandgap of about 1.1 eV so as to absorb impinging radiation with wavelengths shorter than 1.1 micrometers, such that only radiation of wavelengths longer than 1.1 micrometers pass therethrough to the optical sensing element. From the above, it can be seen that a significant advantage of the invention is that the filter required for the sensor to be active only in the desired optical range is an integral part of the sensor structure. Other objects and advantages of this invention will be better appreciated from the following detailed description.

20040629

20070220

20050127

80168.0

BOOSALIS, FANI POLYZOS

INFRARED SENSOR PACKAGE

UNDISCOUNTED

ACCEPTED

ACCEPTED

IMAGE PRINTING SYSTEM

An image printing system is a system which forms images continuously on a long photosensitive material. The image printing system includes an inputting unit for making reservations for cutting of the photosensitive material by the unit of order. The reserved orders for which a cut is reserved by using the inputting unit are memorized in a RAM. The photosensitive material is cut by a paper cutter at a point behind a place where the formation of images is complete for the reserved order.

1. An image printing system for forming images continuously on a long photosensitive material, characterized in that cutting of the photosensitive material by the unit of order is reservable. 2. An image printing system for forming images continuously on a long photosensitive material, comprising: inputting means for making a reservation for cutting of the photosensitive material by the unit of order; storing means for memorizing a reserved order for which the reservation for cutting has been made via the in-putting means; and cutting means for cutting at a point on the photosensitive material behind a place where image formation for the reserved order is complete. 3. The image printing system according to claim 2, further comprising winding means for winding the photo-sensitive material formed with at least an image.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image printing system, and more specifically to an image printing system which forms images continuously on a long photosensitive material. 2. Description of the Related Art Image printing systems of this kind offer an advantage of forming images continuously on a photosensitive material, and therefore is beneficial to entities such as a large-scale image processing station where a large amount of printing is performed. An example of a conventional art of this kind is disclosed in the Patent Document 1. The Patent Document 1 discloses a printer which performs scanning exposure thereby continually forming images on a long photosensitive material. The disclosure includes cutters for cutting the photosensitive material. An example is a cutter which is not utilized in normal operations but used for cutting the photosensitive material when all of the exposed photosensitive material stored in a reservoir after the exposing operation is to be discharged. Another example is a cutter for cutting the photosensitive material when a sensor at the reservoir is unable to detect a loop of the material or when a problem arises in a developing apparatus for example. (Patent Document 1) Japanese Patent Laid-Open No. 9-171219 According to this conventional art, when the photosensitive material must be cut during continuous printing of a plurality of orders, the only way to do so is a forcible cutting. According to such a forcible cutting, a cutting command from the operator is executed right away, but the cutting of the photosensitive material occurs whether or not the order in process has been completed. Cutting of the photosensitive material in the middle of an order is a problem which decreases processing efficiency. It is also an inconvenience to the operator since he cannot leave until a more efficient timing for the cutting has come. SUMMARY OF THE INVENTION It is therefore a primary object of the present invention to provide an image printing system capable of improving convenience without decreasing efficiency in processing. According to an aspect of the present invention, there is provided an image printing system for forming images continuously on a long photosensitive material, characterized in that cutting of the photosensitive material by the unit of order is reservable. According to another aspect of the present invention, there is provided an image printing system for forming images continuously on a long photosensitive material, comprising: inputting means for making a reservation for cutting of the photosensitive material by the unit of order; storing means for memorizing a reserved order for which the reservation for cutting has been made via the inputting means; and cutting means for cutting at a point on the photosensitive material behind a place where image formation for the reserved order is complete. The present invention enables to avoid cutting the photosensitive material in the middle of an order, but to ensure to cut the photosensitive material at an end of the order, making possible to improve processing efficiency. Further, the operator can make reservations for points where a cut is to be made. The operator can now leave the place, which leads to improved convenience. Preferably, the image printing system further comprises winding means for winding the photosensitive material formed with at least an image. In this case, the wound piece of photosensitive material is a piece consisting of a complete order(s), enabling to handle the following operations also by the unit of order. This also improves processing efficiency. The above mentioned object, other objects, characteristics, aspects and advantages of the present invention will become clearer from the following detailed description of an embodiment to be made with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an embodiment of the present invention; FIG. 2 is an external view showing an example of printing apparatuses to which the present invention is applied; FIG. 3 is a schematic diagram outlining a printing apparatus to which the present invention is applied; FIG. 4 shows an example of punch holes made in printing paper; FIG. 5 shows an example of GUI screens presented in a display unit; FIG. 6 shows another example of GUI screens presented in the display; FIG. 7 is a flowchart showing an example of steps for reserving and canceling an order cut; FIG. 8 is a flowchart showing an example of steps to perform an order cut operation; and FIG. 9 is a flowchart showing an example of steps to perform a forcible cut operation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Referring to FIG. 1 through FIG. 3, an image printing system 10 as an embodiment of the present invention can be suitably used at a large-scale image processing station for example where a large amount of printing is performed. The image printing system 10 is a separate system in which formation of images on a printing paper S is performed separately from other tasks that follow, such as development of the images, cutting and sorting, etc. The image printing system 10 includes a printing apparatus 12. The printing apparatus 12 includes a supplying magazine 14 which holds a roll of printing paper S that is photosensitive material to feed, an exposing unit 16 which performs exposure (printing) onto the printing paper S, a winding magazine 18 which winds the exposed printing paper S back into a roll, a control unit 20 which controls operations of the printing apparatus 12, an inputting unit 22 such as a keyboard and a mouse to allow an operator to enter data and issue commands, and a display unit 24 which displays GUIs (GUI: Graphical User Interface) and other information to assist the operator in working with the printing apparatus 12. As shown in FIG. 3, the exposing unit 16 includes a supplying unit 26 for unwinding the roll of printing paper S held in the supplying magazine 14. On a transport path of the long printing paper S unwound by the supplying unit 26, and on a downstream side of the supplying unit 26, there is disposed a paper end sensor 28 for detecting an end of the printing paper S, a splice sensor 30 for detecting a splice in the printing paper S, a paper cutter 32 for cutting the printing paper S in an order cutting, a forcible cutting and other cutting operations, guide rollers 34 for changing a direction of the printing paper S, and a loop forming unit 36. The supplying unit 26 includes rollers in the unit, which are driven by a motor 38. The paper cutter 32 and the guide rollers 34 are driven by a motor 40 and a motor 42 respectively. The loop forming unit 36 absorbs e.g. tension in the printing paper S. In addition, sensors 44 through 50 are provided in order to detect the loop size of the printing paper S formed by the loop forming unit 36. Essentially the same construction is used for loop forming units 62 and 82 to be mentioned later. Before and after the loop forming unit 36 are paper sensors 52 and 54 disposed for detecting positions of the printing paper S. Information from the sensors is used to detect paper jamming, positions of the printing paper S and so on. Other paper sensors 60, 80 and 86 all serve the same purposes. Further along the transporting path of the printing paper S, there are disposed guide rollers 56 for changing the direction of the printing paper S, a punch 58 for forming punch holes as marks on the printing paper S, the paper sensor 60, the loop forming unit 62 and a mark sensor 64 for detecting the marks for purposes of exposing and other operations. The mark sensor 64 detects the punch hole marks formed in the printing paper S, such as a cut mark H1 and an order mark H2 shown in FIG. 4. The cut mark H1 is made for each image (frame) whereas the order mark H2 is made for each order. The loop forming unit 62 is provided with sensors 66 and 68 disposed near by, for detecting a loop formed in the printing paper S. The guide rollers 56 are driven by a motor 70. A pair of rollers 62a and a pair of rollers 62b of the loop forming unit 62 are driven by a motor 72 and a motor 74 respectively. On the downstream side of the mark sensor 64 are transporting roller pairs 76 and 78. Further disposed are the paper sensor 80, a loop forming unit 82, a transporting roller pair 84, and the paper sensor 86. Between the transportation roller pairs 76 and 78, the long printing paper S receives scanning exposure from the exposing unit 88, and thus a plurality of latent images are formed continuously. The loop forming unit 82 is provided with sensors 90 and 92 disposed near by, for detecting a loop in the printing paper S. The transporting roller pairs 76 and 78 are driven by a motor 94. The transporting roller pair 76 includes a pressing roller 76a which is driven to press and release by a motor 96. Likewise, the transporting roller pair 78 includes a pressing roller 78a which is driven to press and release by a motor 98, and the transporting roller pair 84 is driven by a motor 100. The printing paper S is processed by the exposing unit 16 described above, and then wound by the winding magazine 18 into a roll, as undeveloped. Thereafter, the printing paper S is moved manually for example to another unillustrated processing apparatus for development, cutting and sorting, to be made into finished prints. Returning to FIG. 1, the supplying magazine 14, the exposing unit 16, the winding magazine 18, the inputting unit 22, the display unit 24 and so on are controlled by the control unit 20. The control unit 20 includes a CPU 104, a ROM 106, a RAM 108, a hard disc drive (HDD: including hard discs) 110 and a CD-ROM drive 112, all interconnected with a bus 102. The CPU 104 runs a variety of programs stored in the ROM 106, the HDD 110 and so on, sending commands to different components in the printing apparatus 12, a scanner 116 and a communication control unit 118, and controlling operations of the image printing system 10. The ROM 106 stores a startup program and other programs. The startup program is executed by the CPU 104 when power is turned ON to the printing apparatus 12. The execution loads the RAM 108 with an operating system (OS) and other programs stored in the HDD 110 so that variety of processing and controlling operations can be ready to run. The RAM 108 provides space for programs used to control the printing apparatus 12, holding such information as results of operations performed by the programs, temporary data for processing, display data (e.g. text data and image data) and so on for displaying GUIs for example, on a screen of the display unit 24, as well as providing a working area for the CPU 104. The display data prepared in the RAM 108 is sent to the display unit 24. The display unit 24 displays information (e.g. text and images) represented by the display data. Examples of the display are GUI screens in FIG. 5 and FIG. 6. The RAM 108 also memorizes information whether or not each order is a reserved order for which an order cut is reserved (indicated by an order-cut icon 206). The HDD 110 is a device which is controlled by the CPU 104 and reads and records programs, control data, text data, image data and other information to and from the hard discs. In this embodiment, the hard discs in the HDD 110 store programs necessary for performing operations shown in FIG. 7 through FIG. 9, and image data of images to be printed on the printing paper S for each order. The programs are read out and run by the CPU 104, and thus the operations are performed. Each image data is provided with an ID unique to the order it belongs to. The ID corresponds to a reception number displayed at the head of order information 200 shown in FIG. 5 (The reception numbers are represented by numbers “2” through “7” in the figure). The CD-ROM drive 112 reads programs and data stored in a CD-ROM 114, under the control of the CPU 104. The control unit 20 is connected to the scanner 116. The scanner 116 reads images to be formed on the printing paper S and prepares image data. The prepared image data is stored in the HDD 110. Further, the control unit 20 is connected to the communication control unit 118. The communication control unit 118 is connected to a network 120 such as the Internet, and capable of receiving and storing image data from other apparatuses via the network as well as sending and receiving data and uploading/downloading programs and data to and from other apparatuses under the control provided by the CPU 104. The display unit 24 displays GUI screens such as shown in FIG. 5. The screen shows the order information 200, a reserve/cancel button 202 and forcible cut button 204. FIG. 5 shows a case in which there are six orders. It should be noted here that “unit of order” can be any. For example, the unit of order may be a distribution center or an individual consumer. Similarly, if orders are from a school for example, the unit of order may be an individual student. The term “order cut” means that the printing paper S is cut behind a point where a complete set of prints has been finished for a selected order. This enables to cut the printing paper S by the unit of order (at the end of any orders). An order cut can be reserved for each order via the inputting unit 22. A reserved order cut is so indicated by an order-cut icon 206 which appears at the head of the order information 200, and the printing paper S is cut by the paper cutter 32, behind a point where a complete set of prints has been finished for this particular order. The reserve/cancel button 202 is displayed either as a reserve button or as a cancel button. Hereinafter, the button will be called the reserve button 202 or the cancel button 202 depending on situations. When a selection is made from a list of orders displayed on the screen, for an order accompanied by an order-cut icon 206, the reserve/cancel button 202 appears as the cancel button. When the selected order is not accompanied by an order-cut icon 206, then the reserve/cancel button 202 appears as the reserve button. Note that FIG. 5 shows the cancel button. Next, reference is made to FIG. 7 through FIG. 9, to describe examples of operation performed by the image printing system 10. Referring first to FIG. 7, description will cover how an order cut can be reserved and canceled. It should be noted here that an order cut can be reserved and canceled while printing is being made as well as while printing is paused (during a waiting mode). The display unit 24 shows a GUI screen as shown in FIG. 5. When an order is selected on the screen (Step S1), the control unit 20 checks if the selected order is a reserved order or not (Step S3). If the selected order is not a reserved order, the control unit 20 further checks if the reserve button 202 has been pressed (Step S5). The control unit 20 waits until the reserve button 202 has been pressed. When the reserve button 202 is pressed, the control unit 20 checks if error conditions are filled (Step S7). In this step, the error conditions are satisfied if the system is performing an order cut for a reserved order, or if the system is in suspension (due to an error, when responding to the error, or when the system is halted for maintenance). If the error conditions are not filled, the control unit 20 displays on the display unit 24 a reservation confirmation screen as shown in FIG. 6 for example, giving a question such as “You are reserving an order cut. OK? Reception No. 7 (Yes/No)” (Step S9). The control unit 20 checks if the operator has confirmed the reservation on the reservation confirmation screen (Step S11). When a “Yes” button is selected and the confirmation is made on the screen, the control unit 20 checks if a point on the printing paper S which corresponds to the last frame in the selected order (hereinafter called “final-frame point” as necessary) has already passed a cutting point (where the paper cutter 32 is placed) (Step S13). The final-frame point on the printing paper S can be obtained as follows for example: Based on order information stored in the HDD 110 or elsewhere, the control unit 20 calculates how many frames there are after the currently exposed frame (the frame which has been exposed by an exposure head 88) to the last frame. The control unit 20 also can acquire the length of each frame (along the printing paper) for the frames to be printed. Based on these values, the control unit 20 can calculate a distance from the currently exposed frame to the last frame, and thereby identify the final-frame point on the printing paper S. On the other hand, a distance from the exposure position to the paper cutter 32 along the transport path of the printing paper S can be obtained in advance from the structure of printing unit 12. Therefore, the control unit 20 can determine if the final-frame point has passed the cutting point, based on the transportation distance of the printing paper and the final-frame point. If Step 13 finds that the final-frame point has not yet passed the cutting point, the reservation is accepted (Step S15). At this point, the selected order is memorized as a reserved order in the RAM 108, and an order-cut icon 206 is added to the left end of the selected order name displayed on the screen, before the routine comes to an end. On the other hand, if Step S7 finds that the error conditions are filled, the process goes to Step 17, where a massage is displayed saying that the order cut cannot be reserved, together with a specific reason, and the routine comes to the end. If Step S13 finds that the final-frame point on the printing paper S has already passed the cutting point, the process goes to Step S17, to display such a massage that “The order cut cannot be reserved because the final-frame point has already passed the cutting point,” and the routine comes to the end. If Step S11 finds that a “No” button is selected on the reservation confirmation screen, the routine comes to the end. On the other hand, if Step S3 sees that the selected order is a reserved order, then the control unit 20 checks if the cancel button 202 has been pressed (Step S19). The control unit 20 waits until the cancel button 202 has been pressed. When the cancel button 202 is pressed, the control unit 20 displays on the display unit 24 a cancellation confirmation screen, giving a question such as “You are canceling the order cut. OK? Reception No. 7 (Yes/No)” (Step S21). The control unit 20 checks if the operator has confirmed the cancellation (Step S23). When a “Yes” button is selected and the confirmation is made on the screen, the control unit 20 checks if a point on the printing paper S corresponding to the last frame in the selected order has already passed the cutting point (Step S25). If the final-frame point has not yet passed the cutting point, the cancellation is accepted (step S27). At this point, the selected order is memorized as a non-reserved order in the RAM 108, and the order-cut icon 206 is deleted from the left end of the selected order name displayed on the screen, before the routine comes to the end. If Step S23 finds that a “No” button is selected on the cancellation confirmation screen, the routine comes to the end. If Step S25 finds that the final-frame point on the printing paper S has already passed the cutting point, the control unit 20 displays on the display unit 24 a massage saying for example, “The order cut reservation was not cancelled because the final-frame point has already passed the cutting point,” (Step S29) and the routine comes to the end. Next, reference is made to FIG. 8 to describe an example of order cut operation. The order cut operation is enabled when a reserved order enters an in-process phase of the printing operation. In the order cut operation, the control unit 20 checks if the reserved order has all of its prints completed, i.e. if all of the frames included in the order have been exposed by the exposing unit 88 (Step S31). The control unit 20 waits till all of the prints have been completed, and when the printing is over, the paper cutter 32 cuts the printing paper S (Step S33). At this point, the printing paper S is cut behind the final-frame point. The printing paper S which has been cut is wound up by the winding magazine 18 (Step 35), which causes the printing apparatus 12 to pause (Step S37), and to prompt the operator for changing the winding magazine by displaying such a message as “Winding is complete. Change magazine, please,” (Step S39). The control unit 20 checks if the winding magazine 18 has been changed (Step S41) and waits until the winding magazine 18 has been changed. Once the winding magazine 18 is changed, the system resumes the printing operation, beginning a new printing cycle for the next order which comes right after the finished reserved order (Step S43), and ends the order cut operation. Step S43 is not executed if there is no reason to resume the printing e.g. when there are no more orders. Reference will now be made to FIG. 9 to describe an example of forcible cutting operation. The display unit 24 shows a GUI screen as in FIG. 5. When the forcible cut button 204 is pressed (Step S51), the control unit 20 checks if an error condition is filled (Step S53). In this stage, the error condition is filled if the system is halted. If the error conditions are not filled, the control unit 20 displays on the display unit 24 a forcible cut confirmation screen, giving a question such as “You are trying to cut the printing paper right now. OK? (Yes/No)” (Step S55). The control unit 20 checks if the operator has confirmed the forcible cut (Step S57). When a “Yes” button is selected and the confirmation is made on the forcible cut confirmation screen, the control unit 20 has the paper cutter 32 cut the printing paper S right away (Step S59). If Step S57 finds that a “No” button is selected, the operation comes to an end without cutting the printing paper S. After the printing paper S is cut in Step S59, the printing paper S which has been cut is wound up by the winding magazine 18 (Step 61), which causes the printing apparatus 12 to pause (Step S63), and to prompt the operator for changing the winding magazine by displaying such a message as “Winding is complete. Change magazine, please,” (Step S65). The control unit 20 checks if the winding magazine 18 has been changed (Step S67) and waits until the winding magazine 18 has been changed. Once the winding magazine 18 is changed, the system resumes the printing operation, beginning a new printing cycle for the next frame which comes right after the frame that is already printed on the wound roll of printing paper S (Step S69), and ends the forcible cut operation. Step S69 is not executed if there is no reason to resume the printing, e.g. when there are no more frames to print. On the other hand, if Step S53 finds that the error condition is filled, the control unit 20 displays on the display unit 24 a massage, such as “The forcible cut was not successful” (Step S71), and the operation comes to the end without performing a forcible cut. According to the image printing system 10 described as the above, the operator can simply reserve an order cut, then the printing apparatus 12 will automatically detects completion of a printing cycle performed for the reserved order, and causes the paper cutter 32 to cut the printing paper S. This ensures that the printing paper S is reliably cut at the end of each selected order, leading to improved processing efficiency. As has been described, an ability to perform automatic cutting for any orders selected from a continuous chain of orders allows the operator to leave the place once reservations have been made, making the image printing system a convenient system for the operator. Further, it is now possible to make cuts reliably by the unit of order, which means that the wound piece of photosensitive material S is a piece consisting of a complete order(s). This enables to handle the developing and later operations also by the unit of order, leading to improved processing efficiency and consistent printing qualities within each order. Further, the display unit 24 displays not only the reserve/cancel button 202 for a normal order cut but also the forcible cut button 204 for a forcible cut, offering easy options of order cutting in normal operations and forcible cutting in emergency situations. Further, the order information 200 displayed on the screen includes the order-cut icons 206, which makes easy to grasp which orders will cause automatic cutting. An order cut can be reserved for a plurality of orders. Therefore, order cut reservations can be made at one time, which will help the operator who might otherwise forget to make reservations. The reserved order cuts can be cancelled, which provides flexibility to respond to changes in situations after the order cut reservations are made. Still further, the system may also have a function to ask for a choice if “the reserved order cut should be canceled or not” when the printing paper has run out before the end of printing a reserved order. This enables to change a scheduled timing of cut in response to changes in situations. It should be noted here that in the order cut operation example shown in FIG. 8, cutting is made after printing has been finished. This sequence depends upon factors such as how much margin should be taken in the printing paper S after the final frame and how the other relevant apparatuses are laid out. The cutting action may not necessarily take place after the printing (exposing) is finished as long as the printing paper S is cut behind the final-frame point which is the point at which the printing operation is complete for the reserved order. The present invention is applicable to any printing apparatuses and printing systems in which a plurality of images are formed (by exposure) continuously in a longitudinal direction on a long photosensitive material prepared as a roll and then the photosensitive material is cut. The photosensitive material used in the present invention may not necessarily be printing paper, but may be cloth, plastic film and so on. The present invention being described in detail and illustrated thus far, it is obvious that these description and drawings only represent an example of the present invention, and should not be interpreted as limiting the invention. The spirit and scope of the present invention is only limited bywords used in the accompanied claim.

<SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The present invention relates to an image printing system, and more specifically to an image printing system which forms images continuously on a long photosensitive material. 2. Description of the Related Art Image printing systems of this kind offer an advantage of forming images continuously on a photosensitive material, and therefore is beneficial to entities such as a large-scale image processing station where a large amount of printing is performed. An example of a conventional art of this kind is disclosed in the Patent Document 1. The Patent Document 1 discloses a printer which performs scanning exposure thereby continually forming images on a long photosensitive material. The disclosure includes cutters for cutting the photosensitive material. An example is a cutter which is not utilized in normal operations but used for cutting the photosensitive material when all of the exposed photosensitive material stored in a reservoir after the exposing operation is to be discharged. Another example is a cutter for cutting the photosensitive material when a sensor at the reservoir is unable to detect a loop of the material or when a problem arises in a developing apparatus for example. (Patent Document 1) Japanese Patent Laid-Open No. 9-171219 According to this conventional art, when the photosensitive material must be cut during continuous printing of a plurality of orders, the only way to do so is a forcible cutting. According to such a forcible cutting, a cutting command from the operator is executed right away, but the cutting of the photosensitive material occurs whether or not the order in process has been completed. Cutting of the photosensitive material in the middle of an order is a problem which decreases processing efficiency. It is also an inconvenience to the operator since he cannot leave until a more efficient timing for the cutting has come.

<SOH> SUMMARY OF THE INVENTION <EOH>It is therefore a primary object of the present invention to provide an image printing system capable of improving convenience without decreasing efficiency in processing. According to an aspect of the present invention, there is provided an image printing system for forming images continuously on a long photosensitive material, characterized in that cutting of the photosensitive material by the unit of order is reservable. According to another aspect of the present invention, there is provided an image printing system for forming images continuously on a long photosensitive material, comprising: inputting means for making a reservation for cutting of the photosensitive material by the unit of order; storing means for memorizing a reserved order for which the reservation for cutting has been made via the inputting means; and cutting means for cutting at a point on the photosensitive material behind a place where image formation for the reserved order is complete. The present invention enables to avoid cutting the photosensitive material in the middle of an order, but to ensure to cut the photosensitive material at an end of the order, making possible to improve processing efficiency. Further, the operator can make reservations for points where a cut is to be made. The operator can now leave the place, which leads to improved convenience. Preferably, the image printing system further comprises winding means for winding the photosensitive material formed with at least an image. In this case, the wound piece of photosensitive material is a piece consisting of a complete order(s), enabling to handle the following operations also by the unit of order. This also improves processing efficiency. The above mentioned object, other objects, characteristics, aspects and advantages of the present invention will become clearer from the following detailed description of an embodiment to be made with reference to the attached drawings.

20040712

20051213

20050113

69679.0

MATHEWS, ALAN A

IMAGE PRINTING SYSTEM

UNDISCOUNTED

ACCEPTED

ACCEPTED

Bandwidth Limited Sampling Circuit of High Linearity

A bandwidth limited sampling circuit of high linearity may be implemented by using a first circuit portion to limit the bandwidth of the input signals, and using a second circuit portion to sample the bandwidth limited input signal. The first circuit portion and the second circuit portion may be implemented using separate components. In an alternative embodiment, bandwidth limiting is implemented by taking a difference of a sampled input signal from a sampled high frequency components of the input signal.

1. A sampling circuit to sample a source signal received on an input path, a noise signal of high frequency components also being received on said input path, said sampling circuit comprising: a first circuit portion receiving an input signal on said input path, said input signal containing both of said source signal and said noise signal, said first circuit portion generating an output signal by limiting bandwidth of said input signal, wherein said noise signal being substantially absent in said output signal due to said limiting; and a second circuit portion sampling said output signal generated by said first circuit portion. 2. The sampling circuit of claim 1, wherein said first circuit portion comprises a low pass filter. 3. The sampling circuit of claim 2, wherein said second circuit portion is implemented as a switched capacitor circuit. 4. The sampling circuit of claim 3, wherein said low pass filter comprises: a resistor receiving said source signal on one terminal and other terminal of said resistor being connected to a first node; and a first capacitor connected between said first node and a second node. 5. The sampling circuit of claim 4, wherein said first circuit portion further comprises: a first switch connected between said second node and a common mode voltage; and a second switch connected across said first capacitor. 6. The sampling circuit of claim 5, wherein said second circuit portion comprises: a buffer being coupled to receive an input from said first node; a second capacitor connected between a third node and a fourth node; a third switch connected between an output of said buffer and said third node; and a fourth switch connected between said fourth node and said common mode voltage. 7. The sampling circuit of claim 6, wherein said sampling circuit is implemented without requiring a bandwidth limiting element in signal path. 8. The sampling circuit of claim 1, wherein said second circuit portion and said first circuit portion are implemented using a separate set of components. 9. A sampling circuit to sample a source signal received on an input path, a noise signal of high frequency components also being received on said input path, said sampling circuit comprising: a first circuit path sampling an input signal containing both of said source signal and said noise signal; and a second circuit path sampling high frequency components of said input signal, wherein a difference of outputs of said first circuit path and said second circuit path is generated as a sampled output of said sampling circuit, said noise signal being substantially absent in said sampled output due to said difference. 10. The sampling circuit of claim 9, wherein said first circuit path comprises a first switched capacitor circuit. 11. The sampling circuit of claim 10, wherein said second circuit path comprises: a high pass filter providing high frequency components in said input signal as a first output; and a second switched capacitor circuit coupled to said high pass filter sampling said first output. 12. The sampling circuit of claim 11, wherein said high pass filter comprises: a first capacitor receiving said input signal on one terminal and a second terminal of said first capacitor being connected to a first node; and a resistor connected between said first node and a second node. 13. The sampling circuit of claim 12, wherein said second circuit path further comprises: a first switch connected between said second node and a common mode voltage; and a second switch connected across said first capacitor. 14. The sampling circuit of claim 12, wherein said second switched capacitor circuit comprises: a second capacitor connected between a third node and a fourth node; a third switch connected between a fifth node and said third node; and a fourth switch connected between said fourth node and said common mode voltage. 15. The sampling circuit of claim 14, wherein said second circuit path further comprises a buffer connected between said first node and said fifth node. 16. The sampling circuit of claim 15, wherein said sampling circuit is comprised in a correlated double sampler (CDS) which receives a reference level in a first phase and a relative video level in a second phase, said CDS generating actual video level representing a pixel as a difference of said reference level and said relative video level. 17. The sampling circuit of claim 16, further comprising: a third circuit path implemented similar to said second circuit path, wherein said first circuit path samples said reference level along with a corresponding noise signal in said first phase and said relative video level along with a corresponding noise signal in said second phase, said second circuit path sampling high frequency components corresponding to said reference level in said first phase and said third circuit path sampling high frequency components corresponding to said relative video level in said second phase; an amplifier amplifying the difference of outputs of said first circuit path received on a first input and said second circuit path received on a second input at the end of said second phase; a third capacitor connected between a first output of said amplifier and said first input of said amplifier forming a first feedback path in said second phase; a fourth capacitor connected between a second output of said amplifier and said second input of said amplifier forming a second feedback path in said second phase, wherein the difference of outputs provided between said first output and said second output represents said actual video level. 18. A device comprising: a sampling circuit to sample an input signal comprising a source signal and a noise signal of high frequency components, said sampling circuit comprising: a first circuit portion receiving said input signal, said first circuit portion generating an output signal by limiting bandwidth of said input signal, wherein said noise signal being substantially absent in said output signal due to said limiting; and a second circuit portion sampling said output signal generated by said first circuit portion. 19. The device of claim 18, wherein said device captures an image in a digital form, said device comprises: an image sensor allowing a light corresponding to said image to be incident on said image sensor, wherein said image sensor generating an electrical signal proportionate to the intensity of incident light; and an analog front end (AFE) processing said electrical signal, said AFE comprising said sampling circuit, said input signal being generated based on said electrical signal 20. The device of claim 19, wherein said first circuit portion comprises a low pass filter. 21. The device of claim 20, wherein said second circuit portion is implemented as a switched capacitor circuit. 22. The device of claim 21, wherein said low pass filter comprises: a resistor receiving said source signal on one terminal and other terminal of said resistor being connected to a first node; and a first capacitor connected between said first node and a second node. 23. The device of claim 22, wherein said first circuit portion further comprises: a first switch connected between said second node and a common mode voltage; and a second switch connected across said first capacitor. 24. The device of claim 23, wherein said second circuit portion comprises: a buffer being coupled to receive an input from said first node; a second capacitor connected between a third node and a fourth node; a third switch connected between an output of said buffer and said third node; and a fourth switch connected between said fourth node and said common mode voltage. 25. The device of claim 24, wherein said sampling circuit is implemented without requiring a bandwidth limiting element in signal path. 26. The device of claim 25, wherein said second circuit portion and said first circuit portion are implemented using a separate set of components. 27. The device of claim 19, wherein said image sensor contains a plurality of pixels, wherein each of said plurality of pixels stores a charge proportionate to the intensity of incident light and said image sensor generating said input signal proportionate to said charge. 28. The device of claim 21, wherein said AFE further comprises: a programmable gain amplifier (PGA) amplifying an output of said sampling circuit to generate an amplified sampled signal; and an analog to digital converter (ADC) converting said amplified sampled signal to digital values representing said image. 29. The device of claim 28, said device further comprises: a processor processing said digital values; and a memory storing said digital values. 30. The device of claim 29, wherein said image sensor comprises a charge coupled device (CCD). 31. A device comprising: a sampling circuit to sample an input signal containing a source signal and a noise signal of high frequency components, said sampling circuit comprising: a first circuit path sampling said input signal; and a second circuit path sampling high frequency components of said input signal, wherein a difference of outputs of said first circuit path and said second circuit path is generated as a sampled output of said sampling circuit, said noise signal being substantially absent in said sampled output due to said difference. 32. The device of claim 30, wherein said device captures an image in a digital form, said device comprises: an image sensor allowing a light corresponding to said image to be incident on said image sensor, wherein said image sensor generating an electrical signal proportionate to the intensity of incident light; and an analog front end (AFE) processing said electrical signal, said AFE comprising said sampling circuit, said input signal being generated based on said electrical signal. 33. The device of claim 32, wherein said first circuit path comprises a first switched capacitor circuit. 34. The device of claim 33, wherein said second circuit path comprises: a high pass filter providing high frequency components in said input signal as a first output; and a second switched capacitor circuit coupled to said high pass filter sampling said first output. 35. The device of claim 34, wherein said high pass filter comprises: a first capacitor receiving said input signal on one terminal and a second terminal of said first capacitor being connected to a first node; and a resistor connected between said first node and a second node. 36. The device of claim 35, wherein said second circuit path further comprises: a first switch connected between said second node and a common mode voltage; and a second switch connected across said first capacitor. 37. The device of claim 35, wherein said second switched capacitor circuit comprises: a second capacitor connected between a third node and a fourth node; a third switch connected between a fifth node and said third node; and a fourth switch connected between said fourth node and said common mode voltage. 38. The device of claim 37, wherein said second circuit path further comprises a buffer connected between said first node and said fifth node. 39. The device of claim 31, wherein said image sensor contains a plurality of pixels, wherein each of said plurality of pixels stores a charge proportionate to the intensity of incident light and said image sensor generating said input signal proportionate to said charge. 40. The device of claim 38, wherein said AFE further comprises: a programmable gain amplifier (PGA) amplifying an output of said sampling circuit to generate an amplified sampled signal; and an analog to digital converter (ADC) converting said amplified sampled signal to digital values representing said image. 41. The device of claim 40, said device further comprises: a processor processing said digital values; and a memory storing said digital values. 42. The device of claim 40, wherein said image sensor comprises a charge coupled device (CCD). 43. The device of claim 42, wherein said sampling circuit is comprised in a correlated double sampler (CDS) which receives a reference level in a first phase and a relative video level in a second phase, said CDS generating actual video level representing a pixel as a difference of said reference level and said relative video level. 44. The device of claim 43, further comprising: a third circuit path implemented similar to said second circuit path, wherein said first circuit path samples said reference level along with a corresponding noise signal in said first phase and said relative video level along with a corresponding noise signal in said second phase, said second circuit path sampling high frequency components corresponding to said reference level in said first phase and said third circuit path sampling high frequency components corresponding to said relative video level in said second phase; an amplifier amplifying the difference of outputs of said first circuit path received on a first input and said second circuit path received on a second input at the end of said second phase; a third capacitor connected between a first output of said amplifier and said first input of said amplifier forming a first feedback path in said second phase; a fourth capacitor connected between a second output of said amplifier and said second input of said amplifier forming a second feedback path in said second phase, wherein the difference of outputs provided between said first output and said second output represents said actual video level. 45. A sampling circuit to sample a source signal received on an input path, a noise signal of high frequency components also being received on said input path, said sampling circuit comprising: means for receiving an input signal on said input path, said input signal containing both of said source signal and said noise signal; means for generating an output signal by limiting bandwidth of said input signal, wherein said noise signal being substantially absent in said output signal due to said limiting; and means for sampling said output signal to generate a sampled output. 46. The sampling circuit of claim 45, wherein said means for generating passes said input signal through a low pass filter. 47. A sampling circuit to sample a source signal received on an input path, a noise signal of high frequency components also being received on said input path, said sampling circuit comprising: means for sampling an input signal generates a first output, wherein said input signal contains both of said source signal and said noise signal; and means for sampling high frequency components of said input signal generates a second output, wherein a difference of said first output and said second output is generated as a sampled output, said noise signal being substantially absent in said sampled output due to said difference. 48. The sampling circuit of claim 47, wherein said means for sampling an input signal passes said input signal through a first switched capacitor circuit. 49. The sampling circuit of claim 48, wherein said means for sampling high frequency components is operable to: pass said input signal through a high pass filter to provide high frequency components in said input signal as a third output; and pass said third output through a second switched capacitor circuit to generate said second output. 50. A method of sampling a source signal received on an input path, a noise signal of high frequency components also being received on said input path, said method comprising: receiving an input signal on said input path, said input signal containing both of said source signal and said noise signal; generating an output signal by limiting bandwidth of said input signal, wherein said noise signal being substantially absent in said output signal due to said limiting; and sampling said output signal to generate a sampled output. 51. The method of claim 50, wherein said generating comprises passing said input signal through a low pass filter. 52. A method of sampling a source signal received on an input path, a noise signal of high frequency components also being received on said input path, said method comprising: sampling an input signal to generate a first output, wherein said input signal contains both of said source signal and said noise signal; and sampling high frequency components of said input signal to generate a second output, wherein a difference of said first output and said second output is generated as a sampled output, said noise signal being substantially absent in said sampled output due to said difference. 53. The method of claim 52, wherein said sampling an input signal comprises passing said input signal through a first switched capacitor circuit. 54. The method of claim 53, wherein said sampling high frequency components comprises: passing said input signal through a high pass filter to provide high frequency components in said input signal as a third output; and passing said third output through a second switched capacitor circuit to generate said second output.

CROSS REFERENCE TO RELATED APPLICATIONS The present application is related to and claims priority from co_pending U.S. provisional patent application entitled, “Noise Suppression Scheme for Sampling Circuit”, Filed on: Aug. 29, 2003, Ser. No. 60/498,801, Attorney Docket Number: TI-919PS, naming as inventors: AYYAGARI et al, and is incorporated in its entirety herewith into the present application. BACKGROUND OF INVENTION 1. Field of the Invention The present invention relates to the design of electrical/electronic circuits, and more specifically to a method and apparatus for attaining a bandwidth limited sampling circuit of high linearity. 2. Related Art A sampling circuit generally refers to a component which samples a signal level of an input signal (e.g., analog signal) at a particular instant of time and provides an output signal having the signal level to other components for a long duration. In general, a sampling circuit samples an input analog signal at a time point specified by a clock signal, and provides an output signal with the sampled strength to other components for further processing for a long time. An input signal generally contains a source signal and a noise signal/component. It is generally desirable that the sampled output generated by a sampling circuit contain only the source signal component, which is generally referred to as providing a high signal to noise ratio (SNR). A prior approach may remove the noise component by eliminating high frequency components from an input signal as the noise component is generally present at high frequencies. One problem with such an approach is that some of the components performing such removal may have non_linear characteristics, which results in a non_linear response in terms of the overall sampling operation. The non_linearity is undesirable in several environments. Accordingly, what is needed is a bandwidth limited sampling circuit of high linearity providing high SNR. BRIEF DESCRIPTION OF DRAWINGS The present invention will be described with reference to the following accompanying drawings. FIG. 1 is a block diagram illustrating an example environment in which the present invention may be implemented. FIG. 2 is a block diagram of an analog front end illustrating the details (in one embodiment) as relevant to an understanding of several aspects of the present invention. FIG. 3 is a circuit diagram illustrating the details of a sampling circuit in one prior embodiment. FIG. 4 is a circuit diagram illustrating the details of a sampling circuit in an embodiment of the present invention. FIG. 5 is a circuit diagram illustrating the details of a sampling circuit in an alternative embodiment of the present invention. FIG. 6 is a circuit diagram illustrating the details of a correlated double sampler (CDS) used as a sampling circuit in a CCD sensor in one embodiment. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number. DETAILED DESCRIPTION 1. Overview A sampling circuit implemented according to one aspect of the present invention contains a first circuit portion which limits the bandwidth of an input signal containing both source signal and a noise signal, and a second circuit portion samples the bandwidth limited signal. Noise signal, which is generally of high frequency, is substantially absent at an output of the sampling circuit due to the operation of the first circuit portion. As a result, the immunity of the output signal generated by the sampling circuit to noise is enhanced. In one embodiment described below, the first circuit portion is implemented as a R_C circuit operating as a low pass filter, and the second circuit portion is implemented using a switched capacitor. According to another aspect of the present invention, the sampling circuit is implemented using two paths, with the first circuit path sampling the input signal (including source signal and noise signal) and the second circuit path sampling only the high frequency components of the input signal. The sampled signal is generated as a difference of the signals sampled by the two paths. Due to the difference, any high frequency noise components are eliminated, thereby enhancing the immunity of the output signal of the sampling circuit to the noise in the input signal. Various aspects of the present invention are described below with reference to an example problem. Several aspects of the invention are described below with reference to examples for illustration. It should be understood that numerous specific details, relationships, and methods are set forth to provide a full understanding of the invention. One skilled in the relevant art, however, will readily recognize that the invention can be practiced without one or more of the specific details, or with other methods, etc. In other instances, well_known structures or operations are not shown in detail to avoid obscuring the invention. 2. Example Environment FIG. 1 is a block diagram illustrating an example environment in which the present invention can be implemented. Light 119 emanating from image 110 is shown being passed to device 190 (such as a digital camera or a scanner). Device 190 generates pixel data elements representing image 110. The pixel data elements may be forwarded on path 168, and used in several ways, for example, viewed/edited by computer system 180_1, stored in floppy disk 180_2, printed on printer 180_3 or transferred to video player 180_4. Device 190 is shown containing lens 120, CCD (Charge Coupled Device) 130, analog front end (AFE) 140 and post processor 160. Light 119 from image 110 is shown being focused on CCD 130 by lens 120. CCD 130 contains several pixels which are charged proportionate to the product of the intensity of the incident light and the time of exposure to the light. The charge (example of an electrical signal) is converted into voltage in a known way and transferred to AFE 140 on path 134. AFE 140 converts an input signal received on path 134 into digital values (on path 146) representing the image, and transmits the digital values to post processor 150. Input signal on path 134 may contain a source signal representing the voltages and an unwanted noise signal. AFE 140 may employ techniques such as correlated double sampling (which are well known in the relevant arts) in the course of generating the digital values while substantially eliminating the noise signal in the digital values in accordance with several aspects of the present invention as described below in further detail. Post processor 160 (example of a processor) processes the digital values received on path 146, generally to enhance the quality of image represented by the digital values and/or to convert the data into suitable format for storing. The resulting output data on path 168 may be used in several ways by one of the external devices, for example, stored in a memory for processing later. The description is continued with reference to the details of example embodiment of AFE 140. 3. Analog Front End FIG. 2 is a block diagram of AFE 140 illustrating the details (in one embodiment) as relevant to an understanding of several aspects of the present invention. AFE 140 is shown containing sampling circuit 210, programmable gain amplifier (PGA) 220 and analog to digital converter (ADC) 230. Each component is described below in further detail. Sampling circuit 210 samples the voltage levels on a source signal received on path 134 according to various aspects of the present invention to generate an output voltage level which is (substantially) immune from any noise also received on path 134. Sampling circuit 210 may further perform operations such as correlated double sampling (CDS) to generate a voltage level corresponding to a pixel of image 110. PGA 220 amplifies the voltage level received on path 212 by a gain specified typically by a designer depending on image 110. ADC 230 digitizes the amplified voltage signal to generate pixel digital elements on path 146 for further processing. PGA 220 and ADC 230 may be implemented in a known way. The digital elements generated by ADC 230 may accurately reflect image 110 as sampling circuit 210 may be implemented to be immune to any noise present in the input signal received on path 134. Various aspects of the present invention will be clearer by first appreciating a prior approach, which may not include one or several features of the present invention. Accordingly, a prior approach is described below first. 4. Prior Sampling Circuit FIG. 3 is a circuit diagram illustrating the details of a sampling circuit in one prior embodiment. Sampling circuit 300 is shown containing resistor 310, capacitor 320, and switches 330, 340 and 350. Each component is described below. Resistor 310 receives input signal (includes both source signal and a noise signal) on path 311 and provides bandwidth limiting to the input signal, as described in further detail below. Capacitor 320 samples the input signal by charging to the voltage level of input signal when switches 330 and 340 are closed. The time (Ts) duration of sampling is controlled by controlling switches 330 and 340. The voltage across capacitor 320 at the end of sampling time, Ts, represents the sampled voltage level and is provided on path 399. Capacitor 320 discharges through switch 350 when in closed state for next sampling of input signal 311. As is well known in relevant arts, resistor 310 and capacitor 320 together operate as a low pass filter, which limits the bandwidth of input signal 311. Due to the bandwidth limiting, any high frequency CCD noise signal components are removed from signal 311 and low frequency source signal components are provided on path 399. Bandwidth limiting may be achieved by choosing R_C (Rs and C320, wherein Rs is series resistance including resistance of resistor 310, and switches 330 and 340) time constant (Trc) of a desired value (as is well known in the relevant arts) to effectively reduce CCD noise signal components. Thus, sampling circuit 300 samples source signal level received on path 311 at a time instant and provides the sampled voltage on path 399. In addition, sampling circuit 300 performs bandwidth limiting to reduce CCD noise signal components in the sampled output on path 399. One potential problem with sampling circuit 300 is the signal at output may be degraded. The degradation may be caused as the voltage on path 399 may equal a fraction (much less than 1) of the voltage level of signal 311. The reason for such a fraction may be appreciated by understanding that the R_C time constant Trc equals the product of Rs and C320, and generally has a limited value. Due to the requirement that Trc to be greater than or equal to Ts/2, the value of Ts may also be small and capacitor 320 may charge to only a fraction of the voltage level 311 in time duration Ts. Thus, the image quality is diminished due to such partial charging. The degradation of image quality in such a situation may be degraded by the non_linearity introduced by switch 330. At least in case of implementations using technologies such as CMOS transistors, the resistance of switch 330 varies with variation in voltage level of input signal 311. The variable resistance introduces non_linearity into the operation of sampling circuit 300 due to the partial charging. As a result, the image quality is diminished since the sampled output voltage level on path 399 is determined by R_C time constant Trc, which depends on variable resistance R310, thereby degrading the image quality. Various aspects of the present invention overcome some of such problems as described below in further detail. 5. Sampling Circuit FIG. 4 is a circuit diagram illustrating the details of a sampling circuit in an embodiment of the present invention. Merely for illustration, sampling circuit 400 is described with reference to FIGS. 1 and 2, however, sampling circuit 400 can be implemented in other environments as well. Sampling circuit 400 is contained in sampling circuit 210 of FIG. 2. Sampling circuit 400 is shown containing resistor 410, capacitors 420 and 440, buffer 430, and switches 450, 460, 470 and 480. Each component is described below. Broadly, a first circuit portion containing resistor 410, capacitor 420, and switches 450/460 performs bandwidth limiting and the second circuit portion containing capacitor 440, and switches 470/480 performs sampling. As may be apparent, the first circuit portion and second circuit portions are implemented using a separate set of components. Due to the use of two separate portions for bandwidth limiting and sampling respectively, sampling circuit 400 may be substantially immune to noise in the input signal received on path 134, while providing a linear response as described below. Switches 450, 460, 470 and 480 are controlled by a clock signal (not shown). During one phase of the clock signal, switches 460, 470 and 480 are closed and switch 450 is opened to sample input signal on path 134. During another phase of the clock signal, switches 460, 470 and 480 are opened and switch 450 is closed to enable capacitor 420 to sample next signal on path 134. The manner in which bandwidth limiting may be performed is described below first, and then sampling is described later. Resistor 410 receives input signal on path 134 and capacitor 420 charges to the voltage level of input signal 134 when switch 460 is in closed state. Capacitor 420 discharges through switch 450 when in closed state to sample the next signal level. Upper plate of capacitor 420 is connected to resistor 410 and lower plate of capacitor 420 is connected to a common mode voltage via switch 460. Thus, the configuration of resistor 410 and capacitor 420 operates as a low pass filter, which limits the bandwidth by removing high frequency noise signal components and allowing only low frequency source signal components to be present across capacitor 420. The noise signal may be reduced effectively by selecting RC (R410 and C420) time constant to be large. The manner in which sampling may be performed is described below. Capacitor 440, and switches 470 and 480 together sample the voltage level of source signal (which does not include noise signal) received on path 134. Capacitor 440 samples the voltage level stored on capacitor 420 when switches 470 and 480 are closed (switch 460 is also closed on the same time) and provides the sampled voltage level on path 212 when switches 470 and 480 are opened. However, switch 470 is opened before switch 460 is opened to avoid charge injection on capacitor 440. Buffer 430 provides a low impedance drive to the second circuit portion, and thus allowing the required drive current to capacitor 440 to settle (substantially) completely (that is, charges to the sampled voltage level on capacitor 420). As a result, linearity of the sampled voltage level provided on path 212 may not be affected. If buffer 430 is not present, capacitor 440 loads capacitor 420 and thus causes the voltage across capacitor 420 to be reduced. In comparison to the prior circuit described above with reference to FIG. 3, it may be noted that a non_linear switch, whose resistance value changes with input signal swing, is not present in input signal path. Even though switch 470 receives input signal 134 through buffer 430, the path in which switch 470 is present operates with a small time constant (due to absence of series resistance). Thus, the non_linearity of resistance of switch 470 may not affect the sampled output on path 212. As a result, non_linearity in the sampled output signal on path 212 may be negligibly small. However, buffer 430 needs to be capable of receiving high bandwidth of the signal present at the output of capacitor 420. Buffer 430 may also need to have bandwidth greater than RC (R410×C420) time constant in order not to introduce error due to settling and phase shift as is well known in relevant arts. In addition, buffer 430 may need to be capable of receiving a voltage swing as large as the voltage swing in input signal 134 since voltage stored on capacitor 420 approximately equals input voltage 134 (Vi) as given by equation (1). Voltage on capacitor 420=Vi (1_exp(_Ts/RC)) Equation (1) In an example embodiment, when RC time constant equals Ts/2 to reduce CCD noise, voltage on capacitor 420 equals 0.86 of input voltage 134 as given by equation (2) below. Voltage on capacitor 420=Vi (1_exp(—2))=0.86 Vi Equation (2) However, a fast buffer with high input signal swing leads to high power dissipation and is not desirable. In general, a source_follower buffer is very fast (high bandwidth) and consumes less power. However, the input swing capacity is less. Alternatively, a closed loop class_A buffer provides high bandwidth. However, such buffer introduces more noise and also requires more power. Therefore, an alternative embodiment may overcome some of such disadvantages as described below with reference to FIG. 5. 6. Alternative Embodiment FIG. 5 is a circuit diagram illustrating the details of a sampling circuit in an alternative embodiment of the present invention. Merely for illustration, sampling circuit 500 is described with reference to FIGS. 1 and 2, however, sampling circuit 500 can be implemented in other environments as well. Sampling circuit 500 is contained in sampling circuit 210 of FIG. 2. Sampling circuit 500 is shown containing resistor 510, capacitors 520, 540 and 550, buffer 530, and switches 570_1 through 570_6. Each component is described below. Broadly, a first circuit path containing capacitor 540, and switches 570_3/570_5 samples the entire input signal (including both source signal and noise signal) received on path 134, and a second circuit path containing resistor 510, capacitors 520 and 550, buffer 530, and switches 570_1, 570_2, 570_4 and 570_6 samples only the high frequency components in input signal 134. The sampled output signal is generated as a difference of the signals sampled by the two paths 591 and 592. Due to the difference, the high frequency noise signal components received on path 134 may be eliminated and sampling circuit 500 may be substantially immune to noise in the input signal received on path 134, while providing a linear response as described below. Switches 570_1 through 570_6 are controlled by a clock signal (not shown). During one phase of the clock signal, switches 570_2 through 570_6 are closed and switch 570_1 is opened to sample input signal on path 134. During another phase of the clock signal, switches 570_2 through 570_6 are opened and switch 570_1 is closed to enable capacitor 520 to sample next signal on path 134. The manner in which bandwidth limiting and sampling may be performed is described below. Resistor 510, capacitor 520, and switches 570_2 and 570_1 together operate as a high pass filter as would be apparent to one skilled in the relevant art. The high pass filter filters the low frequency components in the input signal received on path 134 and provides the remaining high frequency components on path 533. Buffer 530, capacitor 550, and switches 570_4 and 570_6 operate similar to buffer 430, capacitor 440, and switches 470 and 480 of FIG. 4 respectively. Thus, capacitor 550 samples the output of the high pass filter on path 533 when switches 570_4 and 570_6 are closed and provides the sampled output on path 592 when switches 570_4 and 570_6 are opened. Capacitor 540 samples all frequencies of input signal received on path 134, including both the source signal and the high frequency noise components, when switches 570_3 and 570_5 are closed and provides the sampled output on path 591 when switches 570_3 and 570_5 are opened. The sampled output on path 591 contains all the frequency components in signal 134 and the output on path 592 contains only high frequency components. Therefore, the difference of outputs on paths 591 and 592 contains the sampled output with only low frequency source signal components and thus removes high frequency CCD noise components as desirable. Paths 591 and 592 are contained in path 212 of FIG. 2. As described above with equation (2) in the above illustrative example, voltage across capacitor 520 equals 0.86 Vi when RC (R510 and C520) time constant is Ts/2. As a result, the remaining voltage 0.14 Vi is present across resistor 510, which is the input voltage to buffer 530 on path 533. Therefore, buffer 530 may need to be capable of receiving only 14% of the swing in input voltage (Vi). As a result of the small voltage swing at the input of buffer, the power dissipation is low. Due to the small input voltage swing, a source follower buffer may be used as buffer 530. In general, a source follower has high bandwidth and thus speed of operation is also high. The manner in which the approaches of FIG. 5 can be used to implement correlated double sampling, is described below. 7. Correlated Double Sampler FIG. 6 is a circuit diagram illustrating the details of a correlated double sampler (CDS) used as sampling circuit 210 in CCD environments in one embodiment. CDS 600 is shown containing resistors 615 and 625, capacitors 610, 620, 640, 645, 660 and 665, and switches 670-1 through 670-9, 680-1 and 680-2. In an embodiment, input signal received on path 134 contains reference level and relative video level, which are multiplexed in time domain. Thus, the reference level and the relative video level form the source signal in the corresponding time domain, and the input signal on path 134 contains noise signal in addition to the source signal. The actual video level may be obtained by subtracting relative video level from the reference level, as is well known in the relevant arts. The manner in which CDS 600 generates a sample representing the actual video level is described below. Broadly, CDS 600 samples reference level during one phase (phase I) of clock signal and relative video level during another phase (phase II) of clock signal, and provides the actual video level between output paths 691 and 692. Paths 691 and 692 are contained in path 212 of FIG. 2. CDS 600 may implement the approaches described above with respect to sampling circuit 500 to sample both reference level and relative video level as described below in detail. Such a sampling operation is supported by appropriately closing and opening various switches during different phases. Thus, all the shown switches in CDS 600 may be controlled by a clock signal (not shown). Switches 680_1 and 680_2 are closed to discharge capacitors 610 and 620 respectively prior to sampling input signal 134 and generating an actual video level. The manner in which actual video level may be generated from input signal 134 while substantially eliminating noise signal is described in further detail below. During phase I, a first circuit path containing capacitor 640, and switches 670_3 and 670_6 passes input signal received on path 134 onto capacitor 640, the other end of which is held at a constant voltage by switch 670_6. The passed signal represents all frequency components of (reference level+high frequency noise). A second circuit path containing resistor 625, capacitors 620 and 645, buffer 630, and switches 670_2, 670_4, and 670_7 passes input signal received on path 134 onto capacitor 645 after filtering it through the high-pass filter formed by resistor 625 and capacitor 620. The other end of capacitor 645 is held at a constant voltage by closing switch 670_7, while the second circuit path passes the input signal. At the end of phase I , switches 670_6 and 670_7 are opened. As a result, the difference in voltages across capacitors 640 and 645, which is of (all frequency components_high frequency components) represents the low frequency component of input signal 134. Thus, the low frequency reference level (with the high_frequency noise removed) sampled across capacitors 640 and 645 differentially may be obtained. During phase II, input signal 134 contains a reference video level, and the first circuit path passes input signal 134 onto capacitor 640. The passed signal represents all frequency components of (reference video level+high frequency noise). A third circuit path containing resistor 615, capacitors 610 and 645, buffer 635, and switches 670_1, 670_5, and 670_7 passes input signal received on path 134 after filtering it through the high_pass filter formed by resistor 615 and capacitor 610, onto capacitor 645. It may be noted that switches 670_6 and 670_7 are opened during phase II, thus the other end of capacitors 640 and 645 is not held at a constant voltage, rather connected to the virtual ground of amplifier 650, which is in amplification mode. As a result, capacitors 640 and 645 still hold the sampled reference level during phase I across them. In addition, as capacitors 640 and 645 would be present in series with the filtered relative video level during phase II, the voltage at the output of amplifier 650 represents (low_frequency filtered relative video level sampled in phase II -low_frequency filtered reference level stored on capacitors 640 and 645 in phase I), which in turn represents low_frequency actual video level with noise components removed. Amplifier 650 amplifies the difference on paths 651 and 652 at the end of phase II due to the feedback paths formed by capacitors 660 and 665. The feed back paths are formed by capacitors 660 and 665 since switches 670_8 and 670_9 are closed during phase II. Due to charge sharing between capacitors 640 and 660 and also between capacitors 645 and 665, the difference is amplified and available for further processing on paths 691 and 692. Thus, the difference signal between paths 691 and 692 represents the actual video level containing only low frequency components. Due to the bandwidth limiting, the output may be substantially independent of noise. In addition, linearity of response is maintained/enhanced by using various other features of the present invention. 8. Conclusion While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of the present invention should not be limited by any of the above described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

<SOH> BACKGROUND OF INVENTION <EOH>1. Field of the Invention The present invention relates to the design of electrical/electronic circuits, and more specifically to a method and apparatus for attaining a bandwidth limited sampling circuit of high linearity. 2. Related Art A sampling circuit generally refers to a component which samples a signal level of an input signal (e.g., analog signal) at a particular instant of time and provides an output signal having the signal level to other components for a long duration. In general, a sampling circuit samples an input analog signal at a time point specified by a clock signal, and provides an output signal with the sampled strength to other components for further processing for a long time. An input signal generally contains a source signal and a noise signal/component. It is generally desirable that the sampled output generated by a sampling circuit contain only the source signal component, which is generally referred to as providing a high signal to noise ratio (SNR). A prior approach may remove the noise component by eliminating high frequency components from an input signal as the noise component is generally present at high frequencies. One problem with such an approach is that some of the components performing such removal may have non_linear characteristics, which results in a non_linear response in terms of the overall sampling operation. The non_linearity is undesirable in several environments. Accordingly, what is needed is a bandwidth limited sampling circuit of high linearity providing high SNR.

<SOH> BRIEF DESCRIPTION OF DRAWINGS <EOH>The present invention will be described with reference to the following accompanying drawings. FIG. 1 is a block diagram illustrating an example environment in which the present invention may be implemented. FIG. 2 is a block diagram of an analog front end illustrating the details (in one embodiment) as relevant to an understanding of several aspects of the present invention. FIG. 3 is a circuit diagram illustrating the details of a sampling circuit in one prior embodiment. FIG. 4 is a circuit diagram illustrating the details of a sampling circuit in an embodiment of the present invention. FIG. 5 is a circuit diagram illustrating the details of a sampling circuit in an alternative embodiment of the present invention. FIG. 6 is a circuit diagram illustrating the details of a correlated double sampler (CDS) used as a sampling circuit in a CCD sensor in one embodiment. detailed-description description="Detailed Description" end="lead"? In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number.

20040726

20060321

20050303

65100.0

JEAN PIERRE, PEGUY

BANDWIDTH LIMITED SAMPLING CIRCUIT OF HIGH LINEARITY

UNDISCOUNTED

ACCEPTED

ACCEPTED

AN APPARATUS AND METHOD FOR TRANSMISSION AND REMOTE SENSING OF SIGNALS FROM INTEGRATED CIRCUIT DEVICES

An apparatus and a method for testing semiconductor devices, such as individual integrated circuits in semiconductor chips, by directing a current in each circuit through a respective selected predetermined path to establish, in each circuit, a respective focused magnetic field and converting each such magnetic field into a respective voltage which, when fed to respective amplifier gated with a respective selected frequency, will modulate each such respective voltage. Each such respective voltage is then used to create a respective pulsating magnetic field that when detected by a respective remote magnetic sensor will provide a series of respective signals representative of the current in the respective circuit from which the pulsating magnetic field was derived. By applying each such series of voltages to a lock-in amplifier synchronized at the respective frequencies gating each respective amplifier the current in each circuit being tested can be accurately determined and will be free of errors due to circuit noise or crosstalk between the circuits under test.

1. A system for remotely measuring signals in a circuit under test comprising: means for establishing a first signal in a first selected current path in said circuit; means for establishing a first focused magnetic field at a selected position in said first current path; means for converting said first focused magnetic field into a first Hall voltage; means for transmitting said first Hall voltage to a first frequency gated amplifier; means for gating said amplifier with a first selected signal having a first selected frequency; to modulate, in the amplifier, the converted Hall voltage to provide, at the output of said first amplifier, a second current pulsating at the frequency of said first selected signal; means for transmitting said pulsating flow of current pulses through a second current path to establish in said second current path a second focused magnetic field pulsing at the frequency of said first signal; and, remote magnetic sensing means for detecting said pulsating magnetic field and for providing a electrical output directly proportional to the current in said first path. 2. The system of claim 1 wherein said remote magnetic sensing means is a superconducting quantum interference device. 3. The system of claim 2 the output of said superconducting quantum interference device is coupled to a lock-in amplifier synchronized to the respective frequency pulsing the sensed magnetic field transmitters. 4. A method of remotely detecting and establishing the value of currents in circuits in an integrated semiconductor device comprising the steps of: selecting an integrated semiconductor device; applying a voltage to a first selected circuit in said device to establish a first quiescent current in a selected portion of said first selected circuit; sensing said first quiescent current in said selected portion of said first selected circuit, converting said sensed first quiescent current in said first selected circuit to a first Hall voltage with a first magnetic field concentrator and a first Hall sensor, amplifying said first Hall voltage; modulating said amplified first Hall voltage with a first known frequency, converting said amplified and modulated first Hall voltage with a second magnetic field concentrator to create a first magnetic field pulsing at said known first frequency; and detecting said pulsating first magnetic field with a first remote sensor to provide an output signal proportional to said first sensed current. 5. The method of claim 4 wherein there is further included the steps of: applying a voltage to a second selected circuit in said device to establish a second quiescent current in a selected portion of said second selected circuit; sensing said second quiescent current in said selected portion of said second selected circuit, converting said sensed second quiescent current in said second selected circuit to a second Hall voltage with a third magnetic field concentrator and a second Hall sensor, amplifying said second Hall voltage; modulating said amplified second Hall voltage with a second known frequency, converting said amplified and modulated second Hall voltage with a fourth magnetic field concentrator to create a second magnetic field pulsing at said known second frequency; and detecting said pulsating second magnetic field with a second remote sensor to provide an output signal proportional to said second sensed current. 6. The method of claim 4 wherein there is further included the steps of: applying a selected voltage to a second selected circuit in said chip to establish a current therein; directing said current in said second circuit through a third magnetic field concentrator to establish a steady state magnetic field; converting said second magnetic field into a third voltage applying a second frequency to said third voltage to modulate said third voltage; creating from said third modulated voltage a second pulsating magnetic field that is pulsating at said second frequency; measuring said second pulsating magnetic field with a second remote sensor to convert said second pulsating magnetic field into an output signal proportional to said current in said second selected integrated circuit; applying the output signal of the first remote sensor and the output signal of the second remote sensor to a lock-in amplifier and synchronizing the output signal of said first remote sensor with said first frequency and synchronizing the output signal of said second remote sensor with said second frequency to provide at the output of the lock-in amplifier analog current information from each sensing location without crosstalk between the sensing circuits and without noise in the form of stray extraneous magnetic fields and other induced errors in the tested circuit. 7. A semiconductor testing apparatus comprising: means for holding a semiconductor device to be tested; means for applying an electrical signal to the semiconductor device to be tested to induce in said device a current through a selected path in said device means for establishing a current in a selected current path in said circuit; means for establishing a focused magnetic field at a selected position in said current path; means for converting said focused magnetic field into a Hall voltage; means for transmitting said Hall voltage to a second gated amplifier; means for gating said amplifier with a selected signal with a selected frequency; to modulate, in the amplifier, the converted Hall voltage to provide, at the output of said amplifier, a current pulsating at the frequency of said selected signal; means for transmitting said pulsating current pulses through a current path to establish in said current path a focused magnetic field pulsing at the frequency of said signal; and, remote magnetic sensing means for detecting said pulsating magnetic field and for providing a electrical output proportional to the current in said path.

BACKGROUND OF INVENTION The present invention relates generally to an apparatus and a method for the transmission and sensing of signals in selected portions of semiconductor integrated circuits or chips containing a plurality of individual circuits therein. More particularly, the present invention is directed to a transmission and sensing circuit arrangement especially useful in measuring currents in selected portions of semiconductor Integrated circuits. As is well known in the art, an Integrated circuit chip is comprised of a plurality of individual circuits and, as the elements forming the individual circuits in the integrated circuit chip have become smaller, each individual circuit in the chip also becomes denser causing an exponential increase especially in standby or quiescent currents in the chip and in each such individual circuit. Furthermore these increased currents contribute directly to excessive power dissipation in the chip and affects, through heating, the performance and reliability of the chip. Furthermore defective portions of integrated circuits often draw significantly increased current that can be used to identify defective portions of the integrated circuit. Therefore it is desirable, during the design and testing of an integrated circuit chip, to be able to accurately measure all such quiescent currents at numerous locations in a circuit or at different numerous locations in a plurality of different circuits throughout the chip in order to accurately measure the quiescent current in each circuit or selected portion thereof. In order to characterize and diagnose design or processing efficacy. The prior art attempted to mitigate this problem by monitoring the current at multiple locations in such circuits while under test with built in current sensors (BICS). However, these prior art BICS have various shortcomings that adversely impact the circuits under test for they are interactive and thus introduce parasitic resistance, additional capacitance or inductance, while consuming unproductive chip area by requiring extra inputs and outputs, additional wiring, and tester hardware to transmit the current measurement data off-chip. Accordingly, the present invention is designed to circumvent the above difficulties and avoid the above described difficulties encountered by the prior art. The present invention achieves these ends by providing a circuit layout and current-monitoring apparatus and a method that is passive, remote, has little or no parasitic electrical impact on the circuit under test, minimizes the impact on circuit layout, or area, and provides wide frequency response. The present invention also has minimal impact on circuit performance and provides analog current information from multiple locations simultaneously without crosstalk, interference, or noise. SUMMARY OF INVENTION The present invention achieves all of these desirable results, in a novel circuit; in which the current from a circuit under test, passing to ground, is directed through a first respective selected predetermined path and location to establish in each such circuit under test, a focused magnetic field at a known position; converting each such focused magnetic field into a respective “Hall voltage”, feeding each respective Hall voltage to a respective amplifier that is strobed or gated with a respective selected frequency; to modulate, in the amplifier, the converted Hall voltage and thereby provide, at the output of said amplifier, current pulses at the frequency of said respective selected frequency; passing said current pulses through a second predetermined path to ground to establish in said second path a pulsating magnetic field; and, detecting said pulsating magnetic field with a remote magnetic sensor to provide an electrical output directly proportional to the current in said first path at the respective selected frequency. The remote sensor is preferably a respective superconducting quantum interference device (SQUID) whose output is directed to a lock-in amplifier that is synchronized with the respective frequencies pulsing the sensed magnetic field transmitters. The present invention thus eliminates crosstalk between the individual magnetic field transmitters, noise in the form of extraneous magnetic fields, and increases the output read from each circuit under test. The present invention also teaches a method for the remote magnetic field sensing and readout at known frequencies. The present invention by providing each circuit under test with a first respective magnetic field concentrator arranged to determine the quiescent current in a selected portion of an integrated circuit by sensing the current therein, converting the sensed current to a Hall voltage, modulating this Hall voltage with a known frequency, amplifying the modulated voltage to create a modulated current through a second magnetic field concentrator to create a pulsating magnetic field and detecting this pulsating magnetic field with a remote sensor to provide an output signal proportional to the original sensed current. The current in each circuit, in a plurality of integrated circuits, can be measured by using a distinct frequency for each circuit being measured to create distinct pulsed magnetic fields and distinct pulsed output signals and sending the output signal of each respective remote sensor to a lock-in amplifier that is synchronized with the frequencies used to create the pulsed magnetic fields so that the output of the lock-in amplifier provides analog current information from each sensing location without crosstalk between the sensing circuits and without noise in the form of stray extraneous magnetic fields and other induced errors in the tested circuit. These objects, features and advantages of the present invention will become further apparent to those skilled in the art from the following detailed description taken in conjunction with the accompanying drawings wherein: BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic view of signal transmitter and sensor circuits of the present invention. FIG. 2 illustrates the frequency modulated magnetic field realized by the remote superconducting quantum interference device of FIG. 1; FIG. 3 schematically illustrates a chip having therein a plurality of circuits to be tested in which each circuit is provided with the present invention for determining the current in each circuit. FIG. 4 is a sectional view of a schematically illustrated wafer level test assembly employing the present invention; FIG. 5 schematically illustrates the housing detail of the superconducting quantum interference device used in the present invention, and FIG. 6 is a sectional view of a schematically illustrated package level test assembly employing the present invention. DETAILED DESCRIPTION Referring now to FIGS. 1 through 6 the present invention will be described in detail, wherein: FIG. 1 is a schematic view of signal transmitter and sensor circuits of the present invention; FIG. 2 illustrates the frequency modulated magnetic field realized by the remote superconducting quantum interference device of FIG. 1; FIG. 3 schematically illustrates a chip having therein a plurality of circuits to be tested in which each circuit is provided with the present invention for determining the current in each such circuit; FIG. 4 schematically illustrates a wafer level test assembly employing the present invention; FIG. 5 illustrates the housing detail of the superconducting quantum interference device used in the wafer level test assembly of FIG. 4 and FIG. 6 illustrates a package level test assembly employing the present invention. With reference now to the drawings and especially FIGS. 1 and 2, there is schematically shown, in FIG. 1, a circuit 10 coupled between to a voltage supply 35 and ground 12 through a magnetic field concentrating loop 14. When the circuit 10 is activated it draws a current IDD from the voltage source 35 through the concentrating loop 14 and a magnetic field is generated adjacent the loop. A magnetic field sensor 19, such as a Hall Effect sensor is positioned adjacent to the concentrating loop 14 and within the generated magnetic field created by the current through the conducting loop 14. This generated magnetic field will cause the sensor.19 to produce a Hall Voltage HV that is proportional to the current through the loop 14, i.e. VH∝IDD. This generated Hall Voltage HV is fed to the first input 21 of a strobed or gated amplifier 20. Simultaneously, a selected frequency f, is delivered from the ring oscillator 23 driven by a suitable enable signal from a suitable enable signal source 24, is applied to the second input 22 of the gated amplifier 20 to create a pulsed current IOUT indicated by arrow 27. This pulsed current flow IOUT flows through a second concentrating loop 25 coupled to ground 12.and generates a strobed magnetic field 26. This strobed magnetic field 26 is now detected by SQUID 28. The SQUID 28 measures the amplitude modulated magnetic field 26 and generates the frequency modulated output signal 29 shown in FIG. 2 whose amplitude is directly proportional to the current flow IDD through the first concentrating loop 14. The SQUID 28 is a commercially available device designed to measure extremely weak magnetic signals, and may be either designed for radio frequencies measurements or for direct current measurements. Basically a SQUID is a Josephson junction device, formed of two different superconductors, e.g. a top layer formed of lead with 10% gold or indium and a bottom layer of niobium, separated by an electron tunneling barrier. Such SQUIDs are sensitive enough to detect a change of magnetic energy 100 billion times weaker than the electromagnetic energy required to move a compass needle. Because they are so sensitive they are extremely efficient remote sensors and need not come in contact with a system that they are testing. A radio frequency SQUID is made up of a Josephson junction mounted on a superconducting ring such that when an oscillating current is applied to an external circuit, its voltage changes as an effect of the interaction between it and the ring. The magnetic flux is then measured. The direct current (DC) SQUID is much more sensitive and consists of two Josephson junctions employed in parallel so that electrons tunneling through the junctions demonstrate quantum interference, dependent upon the strength of the magnetic field within a loop and thus demonstrate resistance in response to even tiny variations in a magnetic field. This is the feature that enables the detection of such minute changes in magnetic fields. FIG. 3 schematically illustrates a chip having therein a plurality of circuits to be tested. Each circuit employs the present invention to determine the current in each circuit. In this FIG. 3 there is shown, for example, four separate circuits 30, 31, 32, and 33 each of which is coupled to a voltage source 35, via a respective magnetic concentration loop 30a, 31a, 32a, 33a, and to ground 36. Thus when each circuit is active a respective current exists between the voltage source 35 and ground 36 via its respective concentration loop, i.e., in circuit 30 the current IDD1 passes through the loop 30a, in circuit 31 the current IDD2, passes through the loop 31a, in circuit 32 the current IDD3 passes through the loop 32a, and in circuit 33 the current IDD4 passes through the loop 33a. It is to be understood that although only four such circuits are shown in the present, that as a practical matter when testing a semiconductor chip that many different circuits or portions thereof may need to be checked and measured. Further more, the currents drawn by or existing in each circuit or portion thereof can be different from the current existing in any other circuit. Thus, during test, it is necessary to correctly establish the value of the current in each circuit or portion thereof. That is all the currents, IDD1, 1DD2, IDD3 and IDD4 need to be measured. The present invention does so by placing a respective magnetic concentration loop 30a, 31a, 32a, and 33a in each circuit or portion whose current is to be determined and placing a respective Hall Effect sensor in each respective concentration loop. Thus, In FIG. 3, a Hall sensor 19a is placed in concentration loop 30a, sensor 19b is placed in concentration loop 31a, sensor 19c is placed in concentration loop 32a, and sensor 19d is placed in concentration loop, 33a. The signal from each respective Hall-effect device 19a, 19b, 19c, and 19d is fed to the first input of a respective gated amplifier. Thus the output of Hall-effect device 19a, is fed to the first input 21a of a respective gated amplifier 20a, the output of Hall-effect device 19b, is fed to the first input 21b of a respective gated amplifier 20b, the output of Hall-effect device 19c is fed to the first input 21c of a respective gated amplifier 20c, and the output of Hall-effect device 19d, is fed to the first input 21d of a respective gated amplifier 20d. The other input of each amplifier 20a, 20b, 20c, and 20d is coupled to a respective ring oscillator 23a, 23b, 23c, and 23d so that a respective frequency f1, f2, f3, and f4 may be generated by each respective ring oscillator into each respective amplifier 20a, 20b, 20c, and 20d. These frequencies f1, f2 f3, and f4 cause the output of each respective amplifier 20a, 20b, 20c, and 20d to pulse at the frequency applied to the amplifier. The output of each amplifier 20a, 20b, 20c, and 20d is in turn coupled to ground through a respective magnetic field concentrator 25a, 25b, 25c, and 25d to produce around each magnetic field concentrator 25a, 25b, 25c, and 25d, a respective pulsating magnetic field Bf1, Bf2, Bf3, and Bf4. Each magnetic field Bf1, Bf2, Bf3 and Bf4 is pulsating at the frequency applied to its respective amplifier. Thus the magnetic field Bf1 produced around concentrator 25a is pulsating at the frequency f the magnetic field Bf2 produced around concentrator 25b is pulsating at the frequency f2, the magnetic field Bf3 produced around concentrator 25c is pulsating at the frequency f3, and the magnetic field Bf4 produced around concentrator 25d is pulsating at the frequency f4. These pulsating magnetic fields Bf1, Bf2, Bf3, and Bf4 are detected by the SQUID sensors 28a, 28b, 28,c and 28d respectively. The information detected by each respective SQUID sensor 28a, 28b, 28,c and 28d is transmitted to a lock-in amplifier 30 that is synchronized with the frequencies f1, f2, f3, and f4 so that output of the lock-in amplifier 30 can be set to provide an output indicative of each respective current IDD1, 1DD2, IDD3 or IDD4. FIG. 4 is a sectional view of a schematically illustrated wafer level test assembly employing the present invention. In FIG. 4, a wafer 41 is shown mounted on a wafer chuck 42. The wafer 41 contains a plurality of chips such as chips 41a, 41b, 41c, 41d and 41e. For purposes of illustration only it will be presumed that chip 41b contains the four separate circuits 30, 31, 32, and 33 shown in FIG. 3. The wafer 41 has its back or inactive side 40 mounted on a wafer chuck 42 containing a plurality of SQUID assemblies 28a, 28b, 28c, and 28d. FIG. 5 is an enlargement of a portion of FIG. 4 and schematically illustrates the housing detail of the superconducting quantum interference device used in FIG. 4. Each SQUID assembly 46 is, as shown in FIG. 5 comprised of a plurality of remote SQUIDs 28a, 28b, 28c and 28d mounted in a cooling apparatus 47. Each such SQUID is of course electrically coupled, via lines 29a, 29b, 29c, and 29d to suitable circuitry (not shown) in order to determine the current in each circuit being tested and each is positioned to detect and measure a respective pulsating magnetic field. Thus SQUID 28a detects field Bf1, SQUID 28b detects field Bf2, SQUID 28c detects field Bf3 and SQUID 28d detects field Bf4. Such SQUID assemblies are presently commercially available and can be designed to conform to any desired circuit design or arrangement. For purposes of illustration only, it will be assumed in FIGS. 4 and 5 that the magnetic concentration loops 25a, 25b, 25c and 25d are arranged in line so that a test unit 43, having a plurality of probes 44 positioned in contact with chip 41b, can provide power to the circuits 30a, 31a, 32a, and 33a in a manner well known to the art. When the circuits 30a, 31a, 32a, and 33a are powered up and operated as above described, the pulsating fields Bf1, Bf2, Bf3, and Bf4 are created. When the SQUID sensors 28a, 28b, 28c and 28d are located beneath the chip 41b as shown in FIGS. 4 and 5 each one of the pulsating fields Bf1, Bf2, Bf3, and Bf4 are detected by a respective one of the SQUID sensors 28a, 28b, 28c and 28d. Although in FIG. 5 the SQUID sensors 28a, 28b, 28c and 28d are shown mounted on cold fingers arranged in a line, it should be understood that the SQUID sensors 28a, 28b, 28c and 28d will actually be positioned in any configuration that will permit each to sense a respective one of the pulsating fields Bf1, Bf2, Bf3 and Bf4 created as above described. As shown in FIG. 5 the SQUID sensors 28a, 28b, 28c and 28d are positioned in an evacuated cavity 48 sealed by a protective window 49 that is transparent to the pulsating magnetic fields. Port 50 is used to evacuate the cavity 48 and electrical leads 29a, 29b, 29c and 29d, as shown in FIGS. 3 and 5, lead from each respective sensor to the lock-in amplifier 30. FIG. 6 is a sectional view of a schematically illustrated test arrangement designed to measure, in accordance with the present invention, the currents in a chip 50 under various test conditions. Here a chip 50 has been designed and provided with the necessary magnetic field concentrators, Hall converters, amplifiers and etc. as described in conjunction with FIG. 1 of the present invention. The chip 50 is then mounted such that its active face 52 is mounted against a wiring substrate, as is well known to the art. When so mounted the chip can be electrically activated though the substrate and subjected to various selected tests as is well known to the art. By employing the present invention circuit in selected portions of such substrate mounted chips can be measured by placing the back or inactive face 55 of the chip 50 in contact with a remote sensor arrangement 56, designed for the chip under test, and measuring, as above described, the actual currents in selected portions of the powered up chip. The present invention thus teaches a simple, inexpensive and automatic way of measuring with great accuracy the actual currents in a semiconductor chip under various operating conditions. This completes the description of the preferred embodiment of the invention. Since changes may be made in the above construction without departing from the scope of the invention described herein, it is intended that all the matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. Other alternatives and modifications will now become apparent to those skilled in the art without departing from the spirit and scope of the invention as set forth in the following claims.

<SOH> BACKGROUND OF INVENTION <EOH>The present invention relates generally to an apparatus and a method for the transmission and sensing of signals in selected portions of semiconductor integrated circuits or chips containing a plurality of individual circuits therein. More particularly, the present invention is directed to a transmission and sensing circuit arrangement especially useful in measuring currents in selected portions of semiconductor Integrated circuits. As is well known in the art, an Integrated circuit chip is comprised of a plurality of individual circuits and, as the elements forming the individual circuits in the integrated circuit chip have become smaller, each individual circuit in the chip also becomes denser causing an exponential increase especially in standby or quiescent currents in the chip and in each such individual circuit. Furthermore these increased currents contribute directly to excessive power dissipation in the chip and affects, through heating, the performance and reliability of the chip. Furthermore defective portions of integrated circuits often draw significantly increased current that can be used to identify defective portions of the integrated circuit. Therefore it is desirable, during the design and testing of an integrated circuit chip, to be able to accurately measure all such quiescent currents at numerous locations in a circuit or at different numerous locations in a plurality of different circuits throughout the chip in order to accurately measure the quiescent current in each circuit or selected portion thereof. In order to characterize and diagnose design or processing efficacy. The prior art attempted to mitigate this problem by monitoring the current at multiple locations in such circuits while under test with built in current sensors (BICS). However, these prior art BICS have various shortcomings that adversely impact the circuits under test for they are interactive and thus introduce parasitic resistance, additional capacitance or inductance, while consuming unproductive chip area by requiring extra inputs and outputs, additional wiring, and tester hardware to transmit the current measurement data off-chip. Accordingly, the present invention is designed to circumvent the above difficulties and avoid the above described difficulties encountered by the prior art. The present invention achieves these ends by providing a circuit layout and current-monitoring apparatus and a method that is passive, remote, has little or no parasitic electrical impact on the circuit under test, minimizes the impact on circuit layout, or area, and provides wide frequency response. The present invention also has minimal impact on circuit performance and provides analog current information from multiple locations simultaneously without crosstalk, interference, or noise.

<SOH> SUMMARY OF INVENTION <EOH>The present invention achieves all of these desirable results, in a novel circuit; in which the current from a circuit under test, passing to ground, is directed through a first respective selected predetermined path and location to establish in each such circuit under test, a focused magnetic field at a known position; converting each such focused magnetic field into a respective “Hall voltage”, feeding each respective Hall voltage to a respective amplifier that is strobed or gated with a respective selected frequency; to modulate, in the amplifier, the converted Hall voltage and thereby provide, at the output of said amplifier, current pulses at the frequency of said respective selected frequency; passing said current pulses through a second predetermined path to ground to establish in said second path a pulsating magnetic field; and, detecting said pulsating magnetic field with a remote magnetic sensor to provide an electrical output directly proportional to the current in said first path at the respective selected frequency. The remote sensor is preferably a respective superconducting quantum interference device (SQUID) whose output is directed to a lock-in amplifier that is synchronized with the respective frequencies pulsing the sensed magnetic field transmitters. The present invention thus eliminates crosstalk between the individual magnetic field transmitters, noise in the form of extraneous magnetic fields, and increases the output read from each circuit under test. The present invention also teaches a method for the remote magnetic field sensing and readout at known frequencies. The present invention by providing each circuit under test with a first respective magnetic field concentrator arranged to determine the quiescent current in a selected portion of an integrated circuit by sensing the current therein, converting the sensed current to a Hall voltage, modulating this Hall voltage with a known frequency, amplifying the modulated voltage to create a modulated current through a second magnetic field concentrator to create a pulsating magnetic field and detecting this pulsating magnetic field with a remote sensor to provide an output signal proportional to the original sensed current. The current in each circuit, in a plurality of integrated circuits, can be measured by using a distinct frequency for each circuit being measured to create distinct pulsed magnetic fields and distinct pulsed output signals and sending the output signal of each respective remote sensor to a lock-in amplifier that is synchronized with the frequencies used to create the pulsed magnetic fields so that the output of the lock-in amplifier provides analog current information from each sensing location without crosstalk between the sensing circuits and without noise in the form of stray extraneous magnetic fields and other induced errors in the tested circuit. These objects, features and advantages of the present invention will become further apparent to those skilled in the art from the following detailed description taken in conjunction with the accompanying drawings wherein:

20040728

20061003

20060202

91289.0

G01R3302

VELEZ, ROBERTO

AN APPARATUS AND METHOD FOR TRANSMISSION AND REMOTE SENSING OF SIGNALS FROM INTEGRATED CIRCUIT DEVICES

UNDISCOUNTED

ACCEPTED

G01R

ACCEPTED

APPARATUS FOR TRIMMING METAL

An apparatus for trimming scrap from an aluminum sheet metal blank is provided. The apparatus includes a clamping base comprising a clamping base engagement surface positioned between a clamping base upper surface and a clamping base bottom surface. The clamping base engagement has a clamping base vertically orientated portion and a clamping base angled portion. A steady blade is mounted to the clamping base. The steady blade and the clamping base form a contiguous angled engagement surface. The steady blade engagement surface forms a steady blade trimming edge. An elastic scrap support and an upper clamping element are included. A moving blade includes a moving blade trimming edge formed by the intersection of the moving blade blade-side surface and the moving blade engagement surface. The moving blade engagement surface distributing strain on the aluminum blank as the moving blade trimming edge separates the scrap element from the aluminum blank.

1. An apparatus for trimming scrap from an aluminum sheet metal blank comprising: a clamping base comprising: a clamping base upper surface; a clamping base bottom surface; and a clamping base engagement surface positioned between said clamping base upper surface and said clamping base bottom surface, said clamping base engagement surface comprising: a clamping base vertically orientated portion perpendicular to said clamping base upper surface; and a clamping base angled portion intersecting said clamping base upper surface at an obtuse intersection angle; a steady blade mounted to said clamping base, said steady blade comprising: a steady blade mounting surface coincident with said clamping base vertically orientated portion; a vertically orientated steady blade blade-side surface; and a steady blade engagement surface angled to be substantially coplanar with said clamping base angled portion such that said steady blade and said clamping base form a contiguous angled engagement surface, said steady blade engagement surface intersecting said vertically orientated steady blade blade-side surface to form a steady blade trimming edge; an elastic scrap support comprising a support upper surface parallel and contiguous with said contiguous angled engagement surface; an upper clamping element comprising an upper clamping engagement surface parallel with said contiguous angled engagement surface, said upper clamping engagement surface positioned to engage an aluminum blank positioned between said upper clamping element and said contiguous angled engagement surface, said upper clamping element positioned such that said upper clamping engagement surface is positioned partly over said clamping base angled portion and partially over said steady blade engagement surface; a moving blade movable past said steady blade for trimming said aluminum blank, said moving blade comprising: a moving blade blade-side surface parallel to said steady blade blade-side surface, a moving blade engagement surface generally parallel with the contiguous angled engagement surface, and a moving blade trimming edge formed by the intersection of said moving blade blade-side surface and said moving blade engagement surface, said moving blade engagement surface distributing strain on said aluminum blank as said moving blade trimming edge separates a scrap element from said aluminum blank. 2. An apparatus for trimming scrap from an aluminum sheet metal blank as described in claim 1, further comprising: a stop surface having a first stop surface generally parallel to said clamping base upper surface and a second stop surface generally parallel to said contiguous angled engagement surface, said second stop surface noncontiguous with said contiguous angled engagement surface, said elastic scrap support element mounted on said second stop surface. 3. An apparatus for trimming scrap from an aluminum sheet metal blank as described in claim 1, wherein an upper clamping element blade-side surface is noncontiguous with said moving blade blade-side surface. 4. An apparatus for trimming scrap from an aluminum sheet metal blank as described in claim 1, wherein said moving blade separates said scrap from said aluminum blank by moving said scrap vertically while said elastic scrap support and said moving blade engagement surface act in concert to maintain the orientation of said scrap parallel to said contiguous angled engagement surface. 5. An apparatus for trimming scrap from an aluminum sheet metal blank as described in claim 1, wherein said moving blade engagement surface exerts a normal force onto said scrap. 6. An apparatus for trimming scrap from an aluminum sheet metal blank as described in claim 1, wherein said moving blade and said steady blade are removable. 7. An apparatus for trimming scrap from an aluminum sheet metal blank as described in claim 1, wherein said clamping base comprises: an upper clamping base including said clamping base angled portion and a portion of said clamping base vertically orientated portion; and a lower clamping base mounted to said upper clamping base, said lower clamping base including a lower clamping base height, said lower clamping base replaceable such that said lower clamping base height accommodates a variety of scrap widths. 8. An apparatus for trimming scrap from an aluminum sheet metal blank as described in claim 1, wherein said moving blade trimming edge comprises a curvilinear cutting edge. 9. An apparatus for trimming scrap from an aluminum sheet metal blank as described in claim 1, further comprising: a notch formed in said steady blade trimming edge. 10. An apparatus for trimming scrap from an aluminum sheet metal blank as described in claim 9, wherein said notch comprises: a vertical notch surface intersecting said steady blade engagement surface; and a horizontal notch surface intersecting said steady blade vertical surface. 11. OLE_LINK2 An apparatus for trimming scrap from an aluminum sheet metal blank as described in claim 1, further comprising: a radius formed on said moving blade trimming edge OLE_LINK2. 12. An apparatus for trimming scrap from an aluminum sheet metal blank comprising: a clamping base comprising: a clamping base engagement surface comprising: a clamping base vertically orientated portion; and a clamping base angled portion intersecting said clamping base vertically orientated portion at an obtuse intersection angle; a steady blade mounted to said clamping base, said steady blade comprising: a steady blade mounting surface coincident with said clamping base vertically orientated portion; a vertically orientated steady blade blade-side surface; and a steady blade engagement surface angled to be substantially coplanar with said clamping base angled portion such that said steady blade and said clamping base angled portion form a contiguous angled engagement surface, said steady blade engagement surface intersecting said vertically orientated steady blade blade-side surface to form a steady blade trimming edge; an elastic scrap support comprising a support upper surface contiguous with said contiguous angled engagement surface; an upper clamping element comprising an upper clamping engagement surface parallel with said contiguous angled engagement surface, said upper clamping engagement surface positioned to engage an aluminum blank positioned between said upper clamping element and said contiguous angled engagement surface; a moving blade movable past said steady blade for trimming said aluminum blank, said moving blade comprising: a moving blade blade-side surface parallel to said steady blade blade-side surface, a moving blade engagement surface generally parallel with the contiguous angled engagement surface, and a moving blade trimming edge formed by the intersection of said moving blade blade-side surface and said moving blade engagement surface, said moving blade engagement surface moving said scrap parallel to said contiguous angled engagement surface as said moving blade trimming edge separates said scrap from said aluminum blank. 13. An apparatus for trimming scrap from an aluminum sheet metal blank as described in claim 12, further comprising: a stop surface having a first stop upper surface and a second stop upper surface, said second stop surface generally parallel to said contiguous angled engagement surface, said second stop surface non-contiguous with said contiguous angled engagement surface, said elastic scrap support element mounted on said second stop upper surface. 14. An apparatus for trimming scrap from an aluminum sheet metal blank as described in claim 12, wherein said moving blade separates said scrap from said aluminum blank by moving said scrap vertically while said elastic scrap support and said moving blade engagement surface act in concert to maintain the orientation of said scrap parallel to said contiguous angled engagement surface. 15. An apparatus for trimming scrap from an aluminum sheet metal blank as described in claim 12, wherein said moving blade trimming edge comprises a curvilinear cutting edge. 16. An apparatus for trimming scrap from an aluminum sheet metal blank as described in claim 12, further comprising: a notch formed in said steady blade trimming edge. 17. An apparatus for trimming scrap from an aluminum sheet metal blank as described in claim 16, wherein said notch comprises: a vertical notch surface intersecting said steady blade engagement surface; and a horizontal notch surface intersecting said steady blade vertical surface. 18. An apparatus for trimming scrap from an aluminum sheet metal blank as described in claim 12, further comprising: a radius formed on said moving blade trimming edge. 19. A method of trimming scrap from an aluminum sheet metal blank comprising: placing the aluminum sheet metal blank between a continuous angled engagement surface and an upper clamping engagement surface, said continuous angled surface comprising: a clamping base; and a steady blade mounted to said clamping base; engaging the aluminum sheet metal blank by moving said upper engagement surface towards said continuous angled engagement surface until the aluminum sheet metal blank is secured, said upper clamping engagement surface parallel with said continuous angled engagement surface; engaging the aluminum sheet metal blank with a moving blade, said moving blade comprising: a moving blade blade-side surface parallel; and a moving blade engagement surface generally parallel with said contiguous angled engagement surface; and a moving blade trimming edge formed by the intersection of said moving blade blade-side edge and said moving blade engagement surface; moving a moving blade past said steady blade to trim the scrap from the aluminum sheet metal blank; supporting the scrap utilizing an elastic scrap support, said elastic scrap support comprising a support upper surface contiguous with said contiguous angled engagement surface; and keeping the scrap parallel to said contiguous angled engagement surface using said moving blade engagement surface.

CROSS REFERENCE TO RELATED APPLICATIONS This is a continuation-in-part of U.S. patent application Ser. No. 09/927,281 filed on Aug. 10, 2001. BACKGROUND OF INVENTION The present invention relates generally to an apparatus for trimming metal and more particularly to an apparatus for trimming metal that reduces defects. Modern product design and manufacturing often utilizes a wide variety of materials. Where once low carbon steel predominated, a variety of new materials such as aluminum alloys are now being utilized. These new materials often are capable of reducing weight, increasing strength and improving product efficiency. Although such alternative materials may provide a variety of benefits in product manufacturing and design, these same materials may present difficulties when subjected to manufacturing processes originally designed for low carbon steel. One such manufacturing area where difficulties may arise is in trimming operations. Alternative materials such as aluminum alloys can demonstrate different technological behavior due to differences in mechanical and surface properties and mass density when subjected to trimming operations. These difficulties may give rise to defects arising directly from the trimming process or arising from later operations due to effects caused by the trimming process. One defect known to arise directly from the trimming process is the generation slivers. The generation of slivers, and similar problem finishes, is highly undesirable as such slivers may get attached to the blank surface and distributed to the dies following the trimming operation. The accumulation of slivers on both these dies and the blank surfaces can result in an unacceptable surface finish when the blank is subjected to press operations. The press operations can cause the slivers located on either the dies or the blanks to be forced into the blank surface. Known systems for dealing with such slivers commonly focus on the removal of the slivers from the dies and the blanks rather than prevention of sliver generation. The removal of slivers from the dies and the blanks can be time-consuming and expensive. Often the cleaning of dies requires the interruption of automated stamping processes, which is highly undesirable. Furthermore, close visual inspection of a part surface finish is often required and additional metal work may be required to repair indentations caused by the slivers. These processes add to the cost and time of product manufacture and may lead to an increase in the number of parts that must be scrapped if repair is not feasible. Another approach to the elimination slivers, has been to attempt to increase the accuracy of the alignment of the upper and lower trimming steels. One such standard, that attempts to reduce the problem, requires the gap between the shearing edges to be 10% of the material thickness or less. This standard, however, can translate into gaps of less than 0.1 mm for some sheet metals. Other approaches have further limited the gap to even smaller percentages of material thickness and thereby further decrease the gap. Unfortunately, the tolerances required by such standards often exceed the capabilities of many trim dies and can still result in the production of slivers. This may result in time consuming and expensive procedures that may still fail to eliminate the production of slivers. A second defect that may arise directly in the trimming operation is the production of burrs. Burrs are known to decrease the quality and accuracy of stamped parts and are the sources of potential splits in following operations. Again, current standards attempt to limit the production of burrs through accurate alignment of the upper and lower trimming steels. These standards attempt to minimize the gap between the shearing edges to 10% of the material thickness. Other methods suggest even smaller reduction in gap such as 0-5% of the material thickness. Again, such tolerances may be beyond the capabilities of many trim dies. In addition to those defects arising directly from the trimming operations, defects can arise in later operations such as hemming and flanging operations. These later arising defects often can be traced back to results from the trimming operation. Irregular trim surfaces can result in splits when the trimmed blank is later subjected to hemming or flanging. The production of these post trim defects can add to additional repair and may lead to an increase in the number of parts that must be scrapped if repair is not feasible. Instead of attempting to repair defects after their production or reduce defects by impractical procedures, it would be more efficient and cost effective to improve the trimming process. A reduction in burr, sliver, and split production would decrease costs, reduce manufacturing time, improve surface finish and reduce scrap. It would, therefore, be desirable to have an apparatus for trimming that reduced the production of defects during the trimming process. SUMMARY OF INVENTION It is, therefore, an object of the present invention to provide an apparatus for trimming metal that reduces the generation of defects during operation. In accordance with the object of the present invention, an apparatus for trimming scrap from an aluminum sheet metal blank is provided. The apparatus includes a clamping base comprising a clamping base upper surface, a clamping base bottom surface, and a clamping base engagement surface. The clamping base engagement surface is positioned between the clamping base upper surface and the clamping base bottom surface. The clamping base engagement surface comprises a clamping base vertically orientated portion perpendicular to the clamping base upper surface, and a clamping base angled portion intersecting said clamping base upper surface at an obtuse intersection angle. The apparatus further includes a steady blade mounted to the clamping base. The steady blade includes a steady blade mounting surface coincident with the clamping base vertically orientated portion, a vertically orientated steady blade blade-side surface, and a steady blade engagement surface angled to be substantially coplanar with the clamping base angled portion such that the steady blade and the clamping base form a contiguous angled engagement surface. The steady blade engagement surface intersects the vertically orientated steady blade blade-side surface to form a steady blade trimming edge. The apparatus includes an elastic scrap support comprising a support upper surface parallel and contiguous with the contiguous angled engagement surface. The apparatus includes an upper clamping element comprising an upper clamping engagement surface parallel with the contiguous angled engagement surface. The upper clamping engagement surface is positioned to engage an aluminum blank positioned between the upper clamping element and the contiguous angled engagement surface. The upper clamping element is positioned such that the upper clamping engagement surface is positioned partly over the clamping base angled portion and partially over the steady blade engagement surface. The apparatus includes a moving blade movable past the steady blade for trimming said aluminum blank. The moving blade comprises a moving blade blade-side surface parallel to the steady blade blade-side surface, a moving blade engagement surface generally parallel with the contiguous angled engagement surface, and a moving blade trimming edge formed by the intersection of the moving blade blade-side surface and the moving blade engagement surface. The moving blade engagement surface distributing strain on the aluminum blank as the moving blade trimming edge separates the scrap element from the aluminum blank. Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an illustration of an embodiment of an apparatus for trimming metal in accordance with the present invention; FIG. 2 is an illustration of an alternate embodiment of an embodiment of an apparatus for trimming metal in accordance with the present invention; FIG. 3 is an illustration of the apparatus for trimming metal shown in FIG. 1 in a post-operation stage; FIG. 4 is an illustration of an alternate embodiment of the apparatus for trimming metal shown in FIG. 1, the illustration showing a curvilinear cutting edge; and FIG. 5 is an illustration of a aluminum sheet metal blank formed using the embodiment illustrated in FIG. 4. DETAILED DESCRIPTION Referring now to FIG. 1, which is an illustration of an embodiment of an apparatus 10 for trimming scrap 12 from a sheet metal blank 14 in accordance with the present invention. The apparatus for trimming scrap 10 includes a clamping base 16 and upper clamping element 46 for securing the aluminum sheet metal blank 14 to be trimmed against a steady blade 33. Although the basic mode of clamping and trimming may be known, the present invention provides benefits over known structures and methods. When known systems are used to trim alternate materials such as aluminum alloys, however, an unacceptable generation of material slivers and other defects may occur. In order to minimize slivers, and other defects, prior art processes attempted to minimize the gap 19 between the steady blade 33 and the moving blade 50. However, even upon minimization of the gap 19, also known as trim clearance, the production of slivers may still occur. In addition, as the gap 19 is reduced, often the time and expense of the trimming operation may increase. One reason for the continued production of slivers in the prior art systems bending of the blank 14 during the trimming operation. This bending creates additional tensile strains near the blank upper surface 120 of the blank 14 and compressive strains around the blank lower surface 121. Decreasing the gap 19 can decrease the bending moment but it cannot be eliminated even for zero gap because forces are not concentrated on exactly the leading edges 122,123. This results in the blank 14 cracking first on the blank upper surface 120. Contact pressure between the moving blade 50 and the blank 14 creates hydrostatic pressure that increases the blanks ductility and prevents its failure where they are in contact. As a result, the cracking starts at a point in the blank 14 not in contact with the moving blade 50. In the prior art, this creates a small tongue between the cracking and the sharp edge of the moving blade (not shown) that is bent and broken off creating slivers. To eliminate this phenomena, the present invention has developed an improved apparatus for trimming the scrap 12 from the aluminum sheet metal blank 14. The apparatus includes a clamping base 16 comprised of an upper clamping base 18 and a lower clamping base 20. Although a single piece clamping base 16 may be utilized, a two piece clamping base 16 provides adaptability such that the lower clamping base height 21 can be adjustable through substitution of different lower clamping bases 20 to accommodate a wide variety of scrap widths 23 (see FIG. 3). The clamping base 16 includes a clamping base upper surface 22, a clamping base bottom surface 24, and a clamping base engagement surface 26. The clamping base engagement surface is 26 is comprised of a clamping base vertically orientated portion 28 preferably perpendicular to the clamping base upper surface 22, and a clamping base angled portion 30 intersecting the clamping base upper surface 22 and an obtuse intersection angle 32. This allows the aluminum blank 14 to be retained at an angle relative to the trimming blades 34,50. The present invention further includes a steady blade 33 mounting to the clamping base 16. The steady blade 33 is preferably removably mounted using attachment elements 35 (see FIG. 2) such that it can be easily replaced and serviced during operation. The steady blade 33 comprises a steady blade mounting surface 34 coincident with the clamping base vertically orientated portion 28 to facilitate easy secure mounting. The steady blade 33 further comprises a vertically orientated steady blade blade-side surface 36 and a steady blade engagement surface 38. The steady blade engagement surface 38 is preferably angled to be substantially coplanar with the clamping base angled portion 30 to form a contiguous angled engagement surface 40. The steady blade engagement surface 38 intersects the vertically orientated steady blade blade-side surface 36 to form a steady blade trimming edge 42. The present invention further includes an elastic scrap support 44 mounted in communication with the steady blade 33. The elastic scrap support 44 includes a support surface 46 parallel and contiguous with the contiguous angled engagement surface 40. The elastic scrap support 44 in combination with the contiguous angled engagement surface 40 provides unequalled support of the blank 14 during the trimming process and thereby provide greater control of the scrap 12 and allow for a greater reduction in sliver production. A stop surface 58 is preferably utilized in conjunction with the elastic scrap support 44 to further provide control. One embodiment contemplates a stop surface 58 having a first stop surface 60 generally parallel to the clamping base upper surface 22 and a second stop surface 62 generally parallel to the contiguous angled engagement surface 40. The second stop surface 62 is preferably non-contiguous with the contiguous angled engagement surface 40 to allow the elastic scrap support 44, when mounted on the second stop surface 62, to be positioned in a contiguous relationship with the contiguous angled engagement surface 40. This form of support for the elastic scrap support 44 allows the scrap 12 to be loaded by the moving blade 50 while still retaining original orientation relative to the aluminum sheet metal blank 14. This drastically reduces the aforementioned bending and sliver producing movements. The aluminum sheet metal blank 14 is clamped to the contiguous angled engagement surface 40 utilizing an upper clamping element 46 having an upper clamping surface 48 parallel with the contiguous angled engagement surface 40. The upper clamping engagement surface 48 is positioned to engage the aluminum blank 14 positioned between it and the contiguous angled engagement surface 40. The upper clamping engagement surface 48 is preferably positioned such that the upper clamping engagement surface is positioned partly over the clamping base angled portion 30 and partly over the steady blade engagement surface 38. This is again utilized to reduce the bending of blank 14 or scrap 12 and thereby reduce resultant sliver production. The upper clamping element blade-side surface 39 is preferably non-contiguous with the moving blade blade-side surface 52. The present invention utilizes the moving blade 50 to separate the scrap 12 from the blank 14. The moving blade is also preferably removable for maintenance and replacement using attachment elements 35. The removal of scrap 12 is accomplished by way of moving the moving blade 50 past the steady blade 33 until the scrap 12 is separated. The unique relationship between the moving blade 50, the steady blade 33, and the contiguous angled engagement surface 40 allows further reductions in undesirably bending moments. The moving blade 50 includes a moving blade blade-side surface 52 parallel to the steady blade blade-side surface 36, a moving blade engagement surface 54 generally parallel with the contiguous angled engagement surface 40, and a moving blade trimming edge 56. The moving blade trimming edge is formed by the intersection of the moving blade blade-side surface 52 and the moving blade engagement surface 54. The moving blade engagements surface 54 engages the blank 14 with a surface area parallel to the blank at the same time as the blade trimming edge 56 is generating a trimming load. This acts to distribute strain on the aluminum sheet metal blank 14 as it is being trimmed and thereby reduces slivers. In addition, it converts a vertical loading into a normal load on the aluminum blank 14. Additionally, the moving blade engagement surface 54 insures a movement of the scrap 12 parallel to the blank's 14 original orientation. This works in conjunction with the other mechanical aspects of the present invention to reduce strain and sliver production. A radius 66 can be formed into the moving blade trimming edge 56 of the moving blade 50. By forming a radius 66 on the moving blade trimming edge 56 of the moving blade 50, the strain experienced by the blank 14 is distributed in a wider area which when used in conjunction with the other sliver reduction features of the present invention provides unique benefits. Although the cracking still develops away from the moving blade 50, the tongue has a bigger cross-section and is strong enough to stay on the scrap 12 when the scrap 12 is being separated from the blank 14 (see FIG. 3). This results in a reduction in the production of slivers. It is preferable that the radius 66 be several times less than the blank thickness 68. In one embodiment, for illustrative purposes only, the blank thickness 68 is 0.93 mm and the radius 66 is 0.12 mm. Although a blank thickness 68 and radius 66 have been described, it should be understood that a vast array of radii can be used in conjunction with differing blank thickness and blank materials may be utilized. In alternate embodiments, the present invention can impact an even wider variety of defects. In addition to slivers, trimming defects such as burrs and other surface faults that may result in post-trimming defects such as splits may also be reduced. Most materials have a higher ductility in the compressive stress state than in tensile. Bending the scrap 12 (forces the cracking on the upper surface 20 to dominate. Cracking starting on the blank upper surface 120 from the moving blade 50 generates burrs proportional to the gap 19 that remain on the part side of the trimmed surface. It is preferable, however, to have the cracking start from the steady blade 33 so that any burrs remain on the scrap 12. The unique design of the elastic scrap support 44 alone or in combination with the stop surface 58 has been found to promote cracking of the blank 14 beginning from the steady blade 33. This allows for a wider range of gaps 19. In addition, it reduces the horizontal forces, due to the parallel movement of the scrap 12. Finally, the present embodiment preserves the blanks 14 ductility along the trim line as compared to the prior art and thereby further enhances the blank's 14 usefulness. The present invention may be modified in a variety of ways to alter or improve performance. One embodiment contemplates the notch 70, forming in the steady blade trimming edge 42. The notch 70 is preferably comprised of a vertical notch surface 72 intersecting the steady blade engagement surface 38, and a horizontal notch surface 74 intersecting the steady blade vertical surface 36. The use of the notch 70 can further insure that cracking of the blank 14 originates on the steady blade 33 side of the blank 14 which further assures any burrs are retained on the scrap 12. This can further allow a greater range of gaps 19 to be utilized without developing slivers or burrs on the blank 14. It should be understood that the angle of the blank 14 (i.e. 180°-obtuse angle 32) in FIG. 1 without the notch 70 is preferably 15°-45°. When using the notch 70 as in FIG. 2, the angle of the blank can be increased to larger angles such as 60°-80°. This further improves sliver reduction. Finally, a most unique configuration of the present invention contemplates the use of a moving blade 50 with a curvilinear cutting edge 76 (see FIG. 5). The curvilinear cutting edge 76 allows complex trimming edges 78 to be generated during a single trimming action (see FIG. 5). Normal trimming operations with the requirements of minimal gap 19 often make complex shaped trimming unrealistic due to jamming. The recited structure of the present invention, however, allows for a greater gap 19 tolerance and therefore provides an opportunity to generate complex trimming edges 78 on structures. While particular embodiments of the invention have been shown and described, numerous variations and alternative embodiments will occur to those skilled in the art. Accordingly, it is intended that the invention be limited only in terms of the appended claims.

<SOH> BACKGROUND OF INVENTION <EOH>The present invention relates generally to an apparatus for trimming metal and more particularly to an apparatus for trimming metal that reduces defects. Modern product design and manufacturing often utilizes a wide variety of materials. Where once low carbon steel predominated, a variety of new materials such as aluminum alloys are now being utilized. These new materials often are capable of reducing weight, increasing strength and improving product efficiency. Although such alternative materials may provide a variety of benefits in product manufacturing and design, these same materials may present difficulties when subjected to manufacturing processes originally designed for low carbon steel. One such manufacturing area where difficulties may arise is in trimming operations. Alternative materials such as aluminum alloys can demonstrate different technological behavior due to differences in mechanical and surface properties and mass density when subjected to trimming operations. These difficulties may give rise to defects arising directly from the trimming process or arising from later operations due to effects caused by the trimming process. One defect known to arise directly from the trimming process is the generation slivers. The generation of slivers, and similar problem finishes, is highly undesirable as such slivers may get attached to the blank surface and distributed to the dies following the trimming operation. The accumulation of slivers on both these dies and the blank surfaces can result in an unacceptable surface finish when the blank is subjected to press operations. The press operations can cause the slivers located on either the dies or the blanks to be forced into the blank surface. Known systems for dealing with such slivers commonly focus on the removal of the slivers from the dies and the blanks rather than prevention of sliver generation. The removal of slivers from the dies and the blanks can be time-consuming and expensive. Often the cleaning of dies requires the interruption of automated stamping processes, which is highly undesirable. Furthermore, close visual inspection of a part surface finish is often required and additional metal work may be required to repair indentations caused by the slivers. These processes add to the cost and time of product manufacture and may lead to an increase in the number of parts that must be scrapped if repair is not feasible. Another approach to the elimination slivers, has been to attempt to increase the accuracy of the alignment of the upper and lower trimming steels. One such standard, that attempts to reduce the problem, requires the gap between the shearing edges to be 10% of the material thickness or less. This standard, however, can translate into gaps of less than 0.1 mm for some sheet metals. Other approaches have further limited the gap to even smaller percentages of material thickness and thereby further decrease the gap. Unfortunately, the tolerances required by such standards often exceed the capabilities of many trim dies and can still result in the production of slivers. This may result in time consuming and expensive procedures that may still fail to eliminate the production of slivers. A second defect that may arise directly in the trimming operation is the production of burrs. Burrs are known to decrease the quality and accuracy of stamped parts and are the sources of potential splits in following operations. Again, current standards attempt to limit the production of burrs through accurate alignment of the upper and lower trimming steels. These standards attempt to minimize the gap between the shearing edges to 10 % of the material thickness. Other methods suggest even smaller reduction in gap such as 0-5% of the material thickness. Again, such tolerances may be beyond the capabilities of many trim dies. In addition to those defects arising directly from the trimming operations, defects can arise in later operations such as hemming and flanging operations. These later arising defects often can be traced back to results from the trimming operation. Irregular trim surfaces can result in splits when the trimmed blank is later subjected to hemming or flanging. The production of these post trim defects can add to additional repair and may lead to an increase in the number of parts that must be scrapped if repair is not feasible. Instead of attempting to repair defects after their production or reduce defects by impractical procedures, it would be more efficient and cost effective to improve the trimming process. A reduction in burr, sliver, and split production would decrease costs, reduce manufacturing time, improve surface finish and reduce scrap. It would, therefore, be desirable to have an apparatus for trimming that reduced the production of defects during the trimming process.

<SOH> SUMMARY OF INVENTION <EOH>It is, therefore, an object of the present invention to provide an apparatus for trimming metal that reduces the generation of defects during operation. In accordance with the object of the present invention, an apparatus for trimming scrap from an aluminum sheet metal blank is provided. The apparatus includes a clamping base comprising a clamping base upper surface, a clamping base bottom surface, and a clamping base engagement surface. The clamping base engagement surface is positioned between the clamping base upper surface and the clamping base bottom surface. The clamping base engagement surface comprises a clamping base vertically orientated portion perpendicular to the clamping base upper surface, and a clamping base angled portion intersecting said clamping base upper surface at an obtuse intersection angle. The apparatus further includes a steady blade mounted to the clamping base. The steady blade includes a steady blade mounting surface coincident with the clamping base vertically orientated portion, a vertically orientated steady blade blade-side surface, and a steady blade engagement surface angled to be substantially coplanar with the clamping base angled portion such that the steady blade and the clamping base form a contiguous angled engagement surface. The steady blade engagement surface intersects the vertically orientated steady blade blade-side surface to form a steady blade trimming edge. The apparatus includes an elastic scrap support comprising a support upper surface parallel and contiguous with the contiguous angled engagement surface. The apparatus includes an upper clamping element comprising an upper clamping engagement surface parallel with the contiguous angled engagement surface. The upper clamping engagement surface is positioned to engage an aluminum blank positioned between the upper clamping element and the contiguous angled engagement surface. The upper clamping element is positioned such that the upper clamping engagement surface is positioned partly over the clamping base angled portion and partially over the steady blade engagement surface. The apparatus includes a moving blade movable past the steady blade for trimming said aluminum blank. The moving blade comprises a moving blade blade-side surface parallel to the steady blade blade-side surface, a moving blade engagement surface generally parallel with the contiguous angled engagement surface, and a moving blade trimming edge formed by the intersection of the moving blade blade-side surface and the moving blade engagement surface. The moving blade engagement surface distributing strain on the aluminum blank as the moving blade trimming edge separates the scrap element from the aluminum blank. Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.

20040729

20070403

20050203

69010.0

PETERSON, KENNETH E

APPARATUS FOR TRIMMING METAL

UNDISCOUNTED

CONT-ACCEPTED

ACCEPTED

Iron-Type Golf Club

An iron-type golf club head (20) includes a body (22) having a front wall (28) with a ball-striking surface (40). The body (22) further includes a rear surface (54) that has external rear cavity (56) formed therein. The rear surface (54) includes an upper portion (58) and a lower portion (60). The upper portion (60) is separated from the lower portion (59) by the external rear cavity (56) and at least one groove (64, 66). The lower portion (60) of the rear surface (54) has a notch (62) formed therein, which communicates with the external rear cavity (56). The golf club head (20) preferably has high moments of inertia Izz and Ixx.

1. An iron-type golf club head comprising: a body including a front wall having a ball-striking surface, and the body further including a rear surface having an external rear cavity formed therein, the rear surface including an upper portion and a lower portion, the upper portion being separated from the lower portion by the external rear cavity and at least one groove, the lower portion of the rear surface having a notch formed therein, the notch communicating with the external rear cavity. 2. The iron-type golf club head according to claim 1, wherein the at least one groove extends from the external rear cavity toward a heel end of the club head. 3. The iron-type golf club head according to claim 1, wherein at least one groove includes a first groove extending from the external rear cavity toward a heel end of the club head, and a second groove extending from the external rear cavity toward a toe end of the club head. 4. The iron-type golf club head according to claim 1, wherein the at least one groove has a width of approximately 0.040 inch. 5. The iron-type golf club head according to claim 1, wherein the lower portion of the rear surface extends further rearward than the upper portion of the rear surface. 6. The iron-type golf club head according to claim 5, wherein lower portion of the rear surface extends at least approximately 0.035 inch rearward of the upper portion of the rear surface. 7. The iron-type golf club head according to claim 1, wherein the body includes an undercut recess along at least a portion of the external rear cavity. 8. The iron-type golf club head according to claim 1, wherein the body is composed of a material selected from the group consisting of steel, titanium, titanium alloy, zirconium and zirconium alloy. 9. The iron golf club head according to claim 1, wherein the club head has a moment of inertia Ixx through the center of gravity of at least 2200 g-cm2 and a moment of inertia lzz through the center of gravity of at least 2100 g-cm2. 10. An iron-type golf club head comprising: a body composed of a material selected from the group including stainless steel, titanium and titanium alloy, the body including a front wall having a ball-striking surface, the body further including a rear surface having an external rear cavity formed therein, the rear surface including an upper portion and a lower portion, the lower portion having a notch formed therein, the notch communicating with the external rear cavity, wherein the upper portion of the rear surface is separated from the lower portion by the external rear cavity, a first groove and a second groove, the first groove extending from the external rear cavity toward a heel end, and the second groove extending from the external rear cavity toward a toe end. 11. The iron-type golf club head according to claim 10, wherein each of the first and second grooves has a width of approximately 0.040 inch. 12. The iron-type golf club head according to claim 10, wherein the lower portion of the rear surface extends further rearward than the upper portion of the rear surface. 13. The iron-type golf club head according to claim 12, wherein lower portion of the rear surface extends at least approximately 0.035 inch rearward of the upper portion of the rear surface. 14. The iron-type golf club head according to claim 10, wherein the body includes an undercut recess along at least a portion of the external rear cavity. 15. An iron-type golf club head comprising: a body including a front wall having a ball-striking surface, the body further including a rear surface having an external rear cavity formed therein, the rear surface including an upper portion and a lower portion, the lower portion extending further rearward than the upper portion and having a notch formed therein, the notch communicating with the external rear cavity, wherein the upper portion of the rear surface is separated from the lower portion by the external rear cavity, a first groove and a second groove, the first groove extending from the external rear cavity toward a heel end, and the second groove extending from the external rear cavity toward a toe end. 16. The iron-type golf club head according to claim 15, wherein each of the first and second grooves has a width of approximately 0.040 inch. 17. The iron-type golf club head according to claim 15, wherein lower portion of the rear surface extends at least approximately 0.035 inch rearward of the upper portion of the rear surface.

CROSS REFERENCE TO RELATED APPLICATIONS Not Applicable FEDERAL RESEARCH STATEMENT Not Applicable BACKGROUND OF INVENTION 1. Field of the Invention The present invention relates to an iron-type golf club. More specifically, the present invention relates to an iron-type golf club head with improved perimeter weighting. 2. Description of the Related Art The location and distribution of weight within a golf club is an important factor in the performance of the golf club. In particular, weight placement at the bottom of the golf club head provides a low center of gravity to help propel a golf ball into the air during impact, and weight concentrated at the heel and toe of the golf club head provides a resistance to twisting, or high moment of inertia, during impact. Both the low center of gravity and high moment of inertia are important performance variables that affect playability and feel of the golf club. Alternative designs have resulted in many innovations for varying the weight location and distribution in a golf club head. One approach to varying the weight distribution and location in a golf club head combines materials of different densities in the club head. U.S. Pat. No. 5,776,010 to Helmstetter et al. discloses a high density block or contoured shape attached, via mechanical means, such as friction fit, fasteners or screws, to a reciprocal recess in the golf club head. Although this approach provides the desired performance enhancements, the high density block and reciprocal recess must be machined to precise tolerances, which involves high production costs. Another approach is to add mass at certain areas of the club head. U.S. Pat. Nos. 5,390,924 and 5,395,113 to Antonious disclose a perimeter-weighted, cavity-back iron with integrally formed weight members located on an upper sole surface of a perimeter weight. U.S. Pat. No. 5,026,056 to McNally et al. discloses another perimeter-weighted, cavity-back iron with heel and toe weight pads positioned within the back cavity. U.S. Pat. No. 5,377,985 to Ohnishi discloses an iron-type golf club head with four weights projecting rearward from the face wall at the upper and lower toe side portions and upper and lower heel side portions of the club head. SUMMARY OF INVENTION The present invention provides an iron-type golf club head which has a low center of gravity, a high moment of inertia, reduced vibrations, and a solid feel and appearance. The iron-type golf club head includes a body having a front wall, which provides a ball-striking surface, and a rear surface. The rear surface has an external rear cavity formed therein. The rear surface further includes an upper portion and a lower portion. The lower portion has a notch formed therein, which communicates with the external rear cavity. The upper and lower portions of the rear surface are separated by the external rear cavity and at least one groove. The at least one groove may include a first groove extending from the external rear cavity toward a heel end of the club head and a second groove extending from the external rear cavity toward a toe end of the club head. In addition, the lower portion of the rear surface may extend further rearward of the upper portion. Having briefly described the present invention, the above and further features and advantages thereof will be recognized by those skilled in the pertinent art from the following detailed description of the invention when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a rear perspective view of an iron-type golf club head according to an embodiment of the present invention. FIG. 2 is a front plan view of the iron club head of FIG. 1. FIG. 3 is a rear plan view of the iron club head of FIG. 1. FIG. 4 is a top plan view of the iron club head of FIG. 1. FIG. 5 is a bottom plan view of the iron club head of FIG. 1. FIG. 6 is a heel side view of the iron club head of FIG. 1. FIG. 7 is a toe side view of the iron club head of FIG. 1. FIG. 8 is a cross-sectional view taken generally along line 8-8 of FIG. 3. FIG. 9 is a cross-sectional view taken generally along line 9-9 of FIG. 3. FIG. 10 is a cross-sectional view taken generally along line 10-10 of FIG. 3. FIG. 11 is a front perspective view of a golf club head illustrating the moments of inertia through the center of gravity. DETAILED DESCRIPTION As shown in FIGS. 1-10, an iron-type golf club head in accordance with the present invention is generally designated 20. The club head 20 is a cavity-back iron and includes a body 22 having a heel end 24 and a toe end 26. The body 22 has a front wall 28 for contacting a golf ball and a hosel 30 for receiving a shaft, not shown. The hosel 30 has a bore 32 with an ingress opening 34 and optionally an egress opening 36. In a preferred embodiment the golf club head 20 is composed of a stainless steel, however, those of ordinary skill in the art will appreciate that the golf club head 20 may also be composed of other materials, such as carbon steel, titanium, titanium alloy, zirconium or zirconium alloy. The front wall 28 of golf club head 20 has a ball-striking surface 40 and a back surface 42. The ball-striking surface 40 has a plurality of scorelines 44 formed therein. In a preferred embodiment the top of the hosel 30 is lower than the toe end of the front wall 28, thereby lowering the center of gravity of the club head 20. The golf club head 20 also has a top wall 46, a bottom wall 48, a heel wall 50, a toe wall 52 and a rear surface 54. The top wall 46 extends rearward from the top end of the front wall 28, in a direction opposite the ball-striking surface 40, to the rear surface 54 of the body 22. The bottom wall 48 extends rearward from the bottom end of the front wall 28 to the rear surface 54. The heel wall 50 extends rearward from the heel end 24 of the front wall 28 to the rear surface 54, and the toe wall 52 extends rearward from the toe end 26 of the front wall 28 to the rear surface 54. The rear surface 54, the top wall 46, the bottom wall 48, the heel wall 50 and the toe wall 52 define an external rear cavity 56 in the body 22 of the club head 20. The top wall 46, the bottom wall 48, the heel wall 50 and the toe wall 52 also provide the club head 20 with perimeter weighting to make the club head more forgiving and provide better performance for the typical golfer. The rear surface 54 includes an upper portion 58 and a lower portion 60. A notch 62 is formed in the lower portion 60 of the rear surface 54. The notch 62 is in communication with the external rear cavity 56 to provide enhanced perimeter weighting by removing mass from a central, rear portion of the club head and thereby increasing perimeter weighting at the heel and toe ends of the club head 20. The upper portion 58 of the rear surface 54 is separated from the lower portion 60 by the external rear cavity 56, a first groove 64 and a second groove 66. The first groove 64 extends from the external rear cavity 56 toward the heel end 24 of the body 22, while the second groove 66 extends from the external rear cavity 56 toward the toe end 26 of the body 22. Each groove preferably has a width W of approximately 0.040 inch. The length L1 of the first groove 64 is preferably in the range of 0.25 inch to 0.75 inch. The length L2 of the second groove 66 is preferably in the range of 0.20 inch to 0.50 inch. As best illustrated in FIG. 8, the lower portion 60 of the rear surface 54 extends further rearward than the upper portion 58 by a distance D. In the preferred embodiment the distance D is at least 0.035 inch. Having the lower portion 60 of the rear surface 54 extend rearward of the upper portion 58 provides the club head 20 with an increase in mass at the lower rear portion, which moves the club head's center of gravity further back from the ball-striking surface 40. The golf club head 20 preferably includes an undercut recess 68 in communication with the external rear cavity 56. The undercut recess 68 preferably circumscribes the external rear cavity 56. Alternatively, the undercut recess 68 may extend along only a portion of the external rear cavity 56. A medallion, not shown, is preferably disposed in the external rear cavity 56 of the body 22. FIG. 11 illustrates the axes of inertia through the center of gravity of the golf club head. The axes of inertia are designated X, Y and Z. The X-axis extends from rear of the golf club head 20 through the center of gravity, CG, and to the front wall. The Y-axis extends from the heel end 24 of the golf club head 20 through the center of gravity, CG, and to the toe end 26 of the golf club head 20. The Z-axis extends from the bottom wall through the center of gravity, CG, and to the top wall. As defined in Golf Club Design, Fitting, Alteration & Repair, 4th Edition, by Ralph Maltby, the center of gravity, or center of mass, of the golf club head is a point inside of the club head determined by the vertical intersection of two or more points where the club head balances when suspended. A more thorough explanation of this definition of the center of gravity is provided in Golf Club Design, Fitting, Alteration & Repair. The center of gravity and the moments of inertia of the golf club head 20 are preferably measured using a test frame (XT, YT, ZT), and then transformed to a head frame (XH, YH, ZH). The center of gravity of the golf club head 20 may be obtained using a center of gravity table having two weight scales thereon, as disclosed in U.S. Pat. No. 6,607,452, entitled High Moment Of Inertia Composite Golf Club, and hereby incorporated by reference in its entirety. If a shaft is present, the shaft is removed and replaced with a hosel cube that has a multitude of faces normal to the axes of the golf club head. Given the weight of the golf club head, the scales allow one to determine the weight distribution of the golf club head when the golf club head is placed on both scales simultaneously and weighed along a particular direction, the X, Y or Z direction. In general, the moment of inertia, lzz, about the Z-axis for the golf club head 20 preferably ranges from 2100 g-cm2 to 2700 g-cm2. The moment of inertia, Iyy, about the Y-axis for the golf club head 20 preferably ranges from 400 g-cm2 to 800 g-cm2. The moment of inertia, Ixx, about the X-axis for the golf club head 20 preferably ranges from 2200 g-cm2 to 2800 g-cm2. From the foregoing it is believed that those skilled in the pertinent art will recognize the meritorious advancement of this invention and will readily understand that while the present invention has been described in association with a preferred embodiment thereof, and other embodiments illustrated in the accompanying drawings, numerous changes, modifications and substitutions of equivalents may be made therein without departing from the spirit and scope of this invention which is intended to be unlimited by the foregoing except as may appear in the following appended claims. Therefore, the embodiments of the invention in which an exclusive property or privilege is claimed are defined in the following appended claims.

<SOH> BACKGROUND OF INVENTION <EOH>1. Field of the Invention The present invention relates to an iron-type golf club. More specifically, the present invention relates to an iron-type golf club head with improved perimeter weighting. 2. Description of the Related Art The location and distribution of weight within a golf club is an important factor in the performance of the golf club. In particular, weight placement at the bottom of the golf club head provides a low center of gravity to help propel a golf ball into the air during impact, and weight concentrated at the heel and toe of the golf club head provides a resistance to twisting, or high moment of inertia, during impact. Both the low center of gravity and high moment of inertia are important performance variables that affect playability and feel of the golf club. Alternative designs have resulted in many innovations for varying the weight location and distribution in a golf club head. One approach to varying the weight distribution and location in a golf club head combines materials of different densities in the club head. U.S. Pat. No. 5,776,010 to Helmstetter et al. discloses a high density block or contoured shape attached, via mechanical means, such as friction fit, fasteners or screws, to a reciprocal recess in the golf club head. Although this approach provides the desired performance enhancements, the high density block and reciprocal recess must be machined to precise tolerances, which involves high production costs. Another approach is to add mass at certain areas of the club head. U.S. Pat. Nos. 5,390,924 and 5,395,113 to Antonious disclose a perimeter-weighted, cavity-back iron with integrally formed weight members located on an upper sole surface of a perimeter weight. U.S. Pat. No. 5,026,056 to McNally et al. discloses another perimeter-weighted, cavity-back iron with heel and toe weight pads positioned within the back cavity. U.S. Pat. No. 5,377,985 to Ohnishi discloses an iron-type golf club head with four weights projecting rearward from the face wall at the upper and lower toe side portions and upper and lower heel side portions of the club head.

<SOH> SUMMARY OF INVENTION <EOH>The present invention provides an iron-type golf club head which has a low center of gravity, a high moment of inertia, reduced vibrations, and a solid feel and appearance. The iron-type golf club head includes a body having a front wall, which provides a ball-striking surface, and a rear surface. The rear surface has an external rear cavity formed therein. The rear surface further includes an upper portion and a lower portion. The lower portion has a notch formed therein, which communicates with the external rear cavity. The upper and lower portions of the rear surface are separated by the external rear cavity and at least one groove. The at least one groove may include a first groove extending from the external rear cavity toward a heel end of the club head and a second groove extending from the external rear cavity toward a toe end of the club head. In addition, the lower portion of the rear surface may extend further rearward of the upper portion. Having briefly described the present invention, the above and further features and advantages thereof will be recognized by those skilled in the pertinent art from the following detailed description of the invention when taken in conjunction with the accompanying drawings.

20040729

20060801

20060202

97032.0

A63B5304

HUNTER, ALVIN A

IRON-TYPE GOLF CLUB

UNDISCOUNTED

ACCEPTED

A63B

ACCEPTED

WHEEL TORQUE ESTIMATION IN A POWERTRAIN FOR A HYBRID ELECTRIC VEHICLE

A method for estimating traction wheel torque in a hybrid electric vehicle powertrain that does not require a torque sensor. The method relies upon variables including speed, torque, moments of inertia and angular acceleration of powertrain components. Separate strategy routines are used for a parallel operating mode and for a non-parallel operating mode.

1. A method for determining driving wheel torque for a vehicle having a hybrid electric powertrain, the powertrain comprising an engine, an electric motor, a battery, a generator and gearing that define plural torque flow paths from the engine and the motor to a torque output shaft, the method comprising: calculating angular acceleration of the motor; calculating angular acceleration of the engine; calculating moments of inertia of the motor and the generator; calculating static gearing output torque and motor torque; and estimating total wheel torque as a function of operating variables including inertia of both the motor and the generator, angular acceleration of the engine, motor torque and torque ratio from the motor to the vehicle wheels. 2. A method for determining driving wheel torque for a vehicle having a hybrid electric powertrain with a parallel operating mode, the powertrain comprising an engine, an electric motor, a battery, a generator and gearing that define plural torque flow paths from the engine and the motor to a torque output shaft, the method comprising: calculating angular acceleration of the motor; calculating angular acceleration of the engine; calculating moments of inertia of the motor, the engine and the generator; calculating static gearing output torque and motor torque; and estimating total wheel torque as a function of operating variables including inertia of both the motor and the generator, angular acceleration of the engine, motor torque and torque ratio from the motor to the vehicle wheels. 3. A method for determining driving wheel torque for a vehicle having a hybrid electric powertrain with a non-parallel operating mode, the powertrain comprising an engine, an electric motor, a battery, a generator and gearing that define plural torque flow paths from the engine and the motor to vehicle wheels, the method comprising: calculating angular acceleration of the motor; calculating angular acceleration of the engine; calculating moments of inertia of the motor and the generator; calculating static gearing output torque and motor torque during operation in the non-parallel mode as a function of torque ratio from the generator to the motor and generator torque; and estimating total wheel torque as a function of operating variables including inertia of both the motor and the generator, angular acceleration of the engine, motor torque and torque ratio from the motor to the vehicle wheels. 4. A method for determining driving wheel torque for a vehicle having a hybrid electric powertrain with non-parallel and parallel operating modes, the powertrain comprising an engine, an electric motor, a battery, a generator and gearing that define plural torque flow paths from the engine and the motor to vehicle wheels, the method comprising: calculating angular acceleration of the motor; calculating angular acceleration of the engine; calculating moments of inertia of the motor, the engine and the generator; and calculating static gearing output torque during operation in the parallel mode as a function of operating variables including torque ratio from the generator to the motor, engine torque, engine moment of inertia and engine angular acceleration. 5. The method set forth in claim 1 wherein estimated total wheel torque is computed in accordance with the equation: τtotal—wheel=Tmot2wheel*(τmot−τp@mot+Jgen—couple*dotωeng−Jmot—eff*dotωeng) where: τtotal—wheel=total wheel torque estimate; Tmot2wheel=torque ratio from motor to wheels; τp@mot=torque @ motor shaft; Jgen—couple=coupled moment of inertia of generator and the gear element to which it is connected; dotωeng=engine angular acceleration; Jmot—eff=sum of the lumped motor and gearing inertia and the lumped generator inertia reflected at the motor; and τmot=motor torque. 6. The method set forth in claim 2 wherein estimated total wheel torque is computed in accordance with the equation: τtotal—wheel=Tmot2wheel*(τmot−τp@mot+Jgen—couple*dotωeng−Jmot—eff*dotωeng) where: τtotal—wheel=total wheel torque estimate; Tmot2wheel=torque ratio from motor to wheels; τp@mot=torque @ motor shaft; Jgen—couple=coupled moment of inertia of generator and the gear element to which it is connected; dotωeng=engine angular acceleration; Jmot—eff=sum of the lumped motor and gearing inertia and the lumped generator inertia reflected at the motor; and τmot=motor torque. 7. The method set forth in claim 3 wherein estimated total wheel torque is computed in accordance with the equation: τtotal—wheel=Tmot2wheel*(τmot−τp@mot+Jgen—couple*dotωeng−Jmot—eff*dotωeng) where: τtotal—wheel=total wheel torque estimate; Tmot2wheel=torque ratio from motor to wheels; τp@mot=torque @ motor shaft; Jgen—couple=coupled moment of inertia of generator and the gear element to which it is connected; dotωeng=engine angular acceleration; Jmot—eff=sum of the lumped motor and gearing inertia and the lumped generator inertia reflected at the motor; and τmot=motor torque. 8. The method set forth in claim 3 wherein static gearing output torque is computed in accordance with the equation: τp@mot=Tgen2mot*τgen where: τp@mot=torque at motor shaft; Tgen2mot=torque ratio from generator to motor shaft; and τgen=generator torque. 9. The method set forth in claim 4 wherein static gearing output torque is computed in accordance with the equation: τp@mot=−Tgen2mot*(τeng−Jeng*dotωeng) where: τp@mot=torque at motor shaft; Tgen2mot=torque ratio from engine to motor shaft; τeng=engine torque; Jeng=lumped moment of inertia of engine and the element of the gearing to which it is connection; and dotωeng=engine angular acceleration.

BACKGROUND OF INVENTION 1. Field of the Invention The invention relates to hybrid electric vehicles and a method for estimating vehicle wheel torque. 2. Background Art Unlike pure electric vehicles that use a battery as a power source for a motor in a power flow path to traction wheels, a hybrid electric vehicle has an engine (typically an internal combustion engine) and a high voltage motor for powering the vehicle. A known powertrain configuration for a hybrid electric vehicle consists of two power sources that are connected to the vehicle traction wheels through a planetary gearset. A first power source in this powertrain configuration is a combination of an engine, a generator and a planetary gearset. A second power source comprises an electric drive system including a motor, a generator and a battery subsystem. The battery subsystem acts as an energy storing device for the generator and the motor. In the case of the first power source, the engine speed can be decoupled from the vehicle speed since the generator acts as a torque reaction element for a reaction gear of the planetary gearset. This results in both a mechanical torque flow path and an electromechanical torque flow path, which function in tandem to deliver driving torque to the vehicle traction wheels. The generator reaction torque effects engine speed control as it provides a reaction torque in the torque flow path from the engine. This operating mode commonly is referred to as a non-parallel operating mode. If the generator is braked, the reaction element of the gearset also becomes braked, which establishes a fully mechanical power flow path from the engine to the traction wheels through the gearset. This is referred to as a parallel operating mode. An example of a powertrain configuration of this type can be seen by referring to U.S. patent application Ser. No. 10/248,886, filed Feb. 27, 2003. In the powertrain configuration disclosed in the co-pending patent application, torque is delivered through the powertrain for forward motion only in the case of the first power source. In the case of the second power source, the electric motor draws electric power from the battery and provides driving torque independently of the engine in both forward and reverse drive. In this operating mode, the generator, using battery power, can drive against a one-way clutch on the engine output shaft to propel the vehicle forward. A control system is used to effect integration of the two power sources so that they work together seamlessly to meet the driver's demand for power at the traction wheels without exceeding the limits of the battery subsystem. This is accomplished in the powertrain of the co-pending patent application by coordinating the control of the two power sources. Under normal powertrain operating conditions, a vehicle system controller interprets a driver demand for power, which may be an acceleration or deceleration demand, and then determines a wheel torque demand based on driver demand and powertrain limits. The vehicle system controller also will determine when and how much torque each power source must provide to meet the driver's demand and to achieve specified vehicle performance, such as fuel economy, emissions, driveability, etc. The vehicle system controller can control the engine operating speed for each torque demand so that an efficient operating point on the speed-torque engine characteristic curve will be established. A control system of the type discussed in the preceding paragraphs requires a so-called drive-by-wire control system as the two power sources cooperate seamlessly to achieve optimal performance and efficiency. Such a drive-by-wire system requires a torque monitor strategy to ensure that the control system wheel torque demand and the actual powertrain torque output are within a predefined range so that unintended vehicle acceleration will be avoided. U.S. Pat. No. 5,452,207, which is owned by the assignee of the present invention, discloses a torque estimation method based on a vehicle dynamics model, a torque converter model and an engine torque model. Estimates of torque are obtained from at least two of the models. The torque estimates are weighted according to a predefined strategy and then transferred to a controller for developing torque estimates based on the weighted individual torque estimates. A wheel torque estimation strategy is disclosed also in U.S. Pat. No. 5,751,579, which also is owned by the assignee of the present invention. It provides an estimate of wheel torque based upon engine combustion torque. The estimated torque is proportional to engine acceleration and engine powertrain mass. SUMMARY OF INVENTION The control method of an embodiment of the invention will provide an estimate of the total output torque at the traction wheels for any given driving condition. The torque estimate is used to perform wheel torque monitoring. The method estimates total wheel torque for any given torque of the motor, the generator and the engine in various operating modes. These modes include a non-parallel mode and a parallel mode. When the powertrain configuration is operating in a non-parallel mode, both the engine and the motor cooperate with the gearset to establish both a mechanical torque flow path and an electromechanical torque flow path. In a so-called parallel operating mode, the generator rotor is braked. The method of the invention performs a torque monitoring function to ensure that the vehicle does not accelerate when acceleration is not intended. It eliminates the need for using a torque sensor for measuring total wheel torque. The method uses multiple powertrain inputs, including motor speed, generator speed, engine speed, motor torque, generator torque, engine torque and generator brake status. After calculating engine and motor angular accelerations, the strategy will determine the operating mode. Separate subroutines are used for the non-parallel mode (both positive and negative power flow) and the parallel mode to calculate output torque of the gearset. After the output torque of the gearset is computed in either of the separate subroutines, the strategy computes a total wheel torque estimate. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic representation of a hybrid electric vehicle powertrain for an automotive vehicle capable of embodying the present invention; FIG. 2 is a flowchart illustrating the control software strategy for calculating an estimate of total wheel torque; and FIG. 3 is a sub-routine used in carrying out the routine of FIG. 2 wherein the operating mode for the powertrain is determined. DETAILED DESCRIPTION The powertrain of FIG. 1 includes an internal combustion engine as shown at 10. A planetary gear unit 12 includes a ring gear 14, which is connected driveably to a torque input countershaft gear element 16. The engine torque output shaft is connected driveably to carrier 18 for the planetary gear unit 12. Sun gear 20 of the planetary gear unit 12 is connected driveably to generator 22. The generator is electrically coupled, as shown at 24, to a high voltage electric motor 26, which may be an induction motor. The output rotor of the motor is connected to gear element 28 of torque output countershaft gearing 30. A countershaft gear 32 engages gear 16. A countershaft gear of larger pitch diameter, shown at 34, driveably engages motor output drive gear element 28. A smaller pitch diameter countershaft gear element 36 driveably engages torque output gear 38, which distributes torque to a differential-and-axle assembly 40 to deliver driving torque to vehicle traction wheels 42. A generator brake 44, when applied, anchors the rotor of generator 22, which also anchors sun gear 20. When the generator brake is applied, a mechanical torque flow path from the engine to the differential-and-axle assembly 40 is established. This is referred to as a parallel driving mode. When the brake 44 is released, reaction torque of the generator establishes torque reaction for the sun gear 20 because of the direct mechanical coupling between the sun gear and the generator rotor. Engine speed thus can be controlled by controlling generator. The generator torque is under the control of transmission control module 46, which communicates with vehicle system controller 48. Input variables for the vehicle system controller 48 include a driver-controlled drive range selection at 50 and a signal from an accelerator pedal position sensor 52. Another driver input for the vehicle system controller is a brake pedal position sensor signal 56. Battery 58 is connected to the generator 22 and the motor 26 through a high voltage bus 60. The battery is under the control of the vehicle system controller by means of a contactor control signal at 62. The transmission control module receives from the vehicle system controller a desired wheel torque signal, a desired engine speed signal and a generator brake command as shown at 64. The transmission control module 46 distributes a generator control signal through signal flow path 68 that extends from the module 46 to the brake 44. For the purpose of describing the output torque estimation method, reference will be made to the strategy flow charts of FIGS. 2 and 3. The various method steps involved in the strategy of FIGS. 2 and 3 make use of moment of inertia terms, torque ratio terms, torque terms and angular acceleration terms for elements of the powertrain. Some of these terms are as follows: Jeng is the lumped inertia of engine and carrier; Jgen—couple is the coupled moment inertia of the generator/sun gear; Jmot—eff is the sum of the lumped motor/gear inertia and the lumped generator inertia reflected at the motor; Tgen2mot is the torque ratio from generator shaft to motor shaft; Teng2mot is the torque ratio from engine shaft to motor shaft; and Tmot2wheel is the torque ratio from motor shaft to wheel. In FIG. 2, the strategy routine begins at 70, where the various inputs for the controller 48 are read and then stored in computer memory (RAM). The inputs are motor speed, ωmot, generator speed, ωgen, engine speed, ωeng, motor torque, τmot, generator torque, τgen, engine torque, τeng, and generator brake status (the brake 44 is either eng “on” or “off”). The default operating mode is a non-parallel mode indicated by the statement “Parallel Mode=FALSE.” The first entry in the initialization step sets the parallel mode (internal variable) to FALSE. This occurs in the first entry only. As the strategy routine proceeds, the operating mode will be determined for each control loop of the processor, as will be explained subsequently. The routine then proceeds to action block 72, where motor angular acceleration is calculated. This is done using the functional relationship: dotωmot=dωmot/dt, which is a derivative of the angular velocity of the motor rotor. The result of the calculation at action block 72 is stored in memory, and the routine then proceeds to action block 74 where the engine angular acceleration is calculated. This is done in accordance with the following relationship: dotωeng=dωeng/dt, which is the derivative of the angular engine velocity. After the information obtained at action block 74 is stored in memory, the routine proceeds to action block 76, where the operating mode is determined. The routine at action block 76 is a subroutine indicated in FIG. 3. That subroutine will determine whether the powertrain is in the parallel mode or in the non-parallel mode. As explained previously, the generator brake is applied when the powertrain is in the parallel mode and is released to establish plural power flow paths in the non-parallel mode. As previously explained also, the default operating mode is a non-parallel mode. The routine then will proceed to decision block 78, where the controller will determine whether the generator brake is on. If the inquiry at 78 is negative, the operating mode set during initialization is confirmed. If the inquiry at 78 is positive, the routine will proceed to decision block 80, where it is determined whether the generator speed is less than a predetermined threshold generator speed Cgen—spd. If the result of the inquiry at 80 is negative, the non-parallel mode determination is confirmed. If the result of the inquiry at 80 is positive, the routine then will proceed to decision block 82, where it is determined whether the generator torque is less than a predetermined threshold Cgen—tq. If the result of the inquiry at 82 is negative, the non-parallel mode is confirmed. If the result of the inquiry at 82 is positive, the parallel mode is set to “TRUE”, which is a change in mode from non-parallel operation to parallel operation. This occurs at action block 84. If the powertrain is in a parallel operating mode, as determined at decision block 86′, the control routine will proceed to decision block 88, where it is determined whether the generator speed is less than a predetermined threshold generator speed Cgen—spd. If the result of the inquiry at 88 is positive, the operating mode is changed at action block 90 from the parallel mode to the non-parallel mode (the setting is “FALSE”). If the result of the inquiry at 88 is negative, the routine proceeds to action block 92, where it is determined whether the generator torque is less than a predetermined threshold Cgen—tq. If the result of the inquiry at 92 is positive, again the operating mode is changed at action block 90 from the parallel mode to the non-parallel mode. If the result of the inquiry at 92 is negative, the parallel mode at decision block 88 is confirmed. Likewise, a negative result of the inquiry at decision block 88 is a confirmation of the parallel mode indicated at 86′. Based upon the operating mode that is determined in the subroutine of FIG. 3, the method uses one of two different ways to calculate planetary output torque at the motor shaft. If the powertrain is in a non-parallel operating mode as confirmed at 86 in FIG. 2, the routine of FIG. 2 will proceed to action block 94, where static planetary output torque is calculated. This is done using the relationship: τp@mot=Tgen2mot*τgen where: τp@mot=torque at motor shaft; Tgen2mot=torque ratio from generator to motor shaft; and τgen=generator torque. On the other hand, if it is determined that the powertrain is in the parallel operating mode at 86, the routine will proceed to action block 96, where static planetary output torque is computed using the relationship: τp@mot=−Tgen2mot*(τgen−Jeng*dotωeng) where: τp@mot=torque at motor shaft; Tgen2mot=torque ratio from engine to motor shaft; τeng=engine torque; Jeng=lumped moment of inertia of engine and the element of the gearing to which it is connection; and dotωeng=engine angular acceleration. Following either of the calculations at action blocks 94 and 96, the routine will proceed to action block 98 where the total wheel torque is estimated. This is done using the following relationship: τtotal—wheel=Tmot2wheel*(τmot−τp@mot+Jgen—couple*dotωeng−Jmot—eff*dotωeng) where: τtotal—wheel=total wheel torque estimate; Tmot2wheel=torque ratio from motor to wheels; τmot=torque @ motor shaft; Jgen—couple=coupled moment of inertia of generator and the element to which it is connected; dotωeng=engine angular acceleration; and Jmoteff=sum of the lumped motor and gearing inertia and the lumped generator inertia reflect at the motor. Although an embodiment of the invention has been described, it will be apparent to a person skilled in the art that modifications may be made to the invention without departing from the scope of the invention. All such modifications and equivalents thereof are intended to be covered by the following claims.

<SOH> BACKGROUND OF INVENTION <EOH>1. Field of the Invention The invention relates to hybrid electric vehicles and a method for estimating vehicle wheel torque. 2. Background Art Unlike pure electric vehicles that use a battery as a power source for a motor in a power flow path to traction wheels, a hybrid electric vehicle has an engine (typically an internal combustion engine) and a high voltage motor for powering the vehicle. A known powertrain configuration for a hybrid electric vehicle consists of two power sources that are connected to the vehicle traction wheels through a planetary gearset. A first power source in this powertrain configuration is a combination of an engine, a generator and a planetary gearset. A second power source comprises an electric drive system including a motor, a generator and a battery subsystem. The battery subsystem acts as an energy storing device for the generator and the motor. In the case of the first power source, the engine speed can be decoupled from the vehicle speed since the generator acts as a torque reaction element for a reaction gear of the planetary gearset. This results in both a mechanical torque flow path and an electromechanical torque flow path, which function in tandem to deliver driving torque to the vehicle traction wheels. The generator reaction torque effects engine speed control as it provides a reaction torque in the torque flow path from the engine. This operating mode commonly is referred to as a non-parallel operating mode. If the generator is braked, the reaction element of the gearset also becomes braked, which establishes a fully mechanical power flow path from the engine to the traction wheels through the gearset. This is referred to as a parallel operating mode. An example of a powertrain configuration of this type can be seen by referring to U.S. patent application Ser. No. 10/248,886, filed Feb. 27, 2003. In the powertrain configuration disclosed in the co-pending patent application, torque is delivered through the powertrain for forward motion only in the case of the first power source. In the case of the second power source, the electric motor draws electric power from the battery and provides driving torque independently of the engine in both forward and reverse drive. In this operating mode, the generator, using battery power, can drive against a one-way clutch on the engine output shaft to propel the vehicle forward. A control system is used to effect integration of the two power sources so that they work together seamlessly to meet the driver's demand for power at the traction wheels without exceeding the limits of the battery subsystem. This is accomplished in the powertrain of the co-pending patent application by coordinating the control of the two power sources. Under normal powertrain operating conditions, a vehicle system controller interprets a driver demand for power, which may be an acceleration or deceleration demand, and then determines a wheel torque demand based on driver demand and powertrain limits. The vehicle system controller also will determine when and how much torque each power source must provide to meet the driver's demand and to achieve specified vehicle performance, such as fuel economy, emissions, driveability, etc. The vehicle system controller can control the engine operating speed for each torque demand so that an efficient operating point on the speed-torque engine characteristic curve will be established. A control system of the type discussed in the preceding paragraphs requires a so-called drive-by-wire control system as the two power sources cooperate seamlessly to achieve optimal performance and efficiency. Such a drive-by-wire system requires a torque monitor strategy to ensure that the control system wheel torque demand and the actual powertrain torque output are within a predefined range so that unintended vehicle acceleration will be avoided. U.S. Pat. No. 5,452,207, which is owned by the assignee of the present invention, discloses a torque estimation method based on a vehicle dynamics model, a torque converter model and an engine torque model. Estimates of torque are obtained from at least two of the models. The torque estimates are weighted according to a predefined strategy and then transferred to a controller for developing torque estimates based on the weighted individual torque estimates. A wheel torque estimation strategy is disclosed also in U.S. Pat. No. 5,751,579, which also is owned by the assignee of the present invention. It provides an estimate of wheel torque based upon engine combustion torque. The estimated torque is proportional to engine acceleration and engine powertrain mass.

<SOH> SUMMARY OF INVENTION <EOH>The control method of an embodiment of the invention will provide an estimate of the total output torque at the traction wheels for any given driving condition. The torque estimate is used to perform wheel torque monitoring. The method estimates total wheel torque for any given torque of the motor, the generator and the engine in various operating modes. These modes include a non-parallel mode and a parallel mode. When the powertrain configuration is operating in a non-parallel mode, both the engine and the motor cooperate with the gearset to establish both a mechanical torque flow path and an electromechanical torque flow path. In a so-called parallel operating mode, the generator rotor is braked. The method of the invention performs a torque monitoring function to ensure that the vehicle does not accelerate when acceleration is not intended. It eliminates the need for using a torque sensor for measuring total wheel torque. The method uses multiple powertrain inputs, including motor speed, generator speed, engine speed, motor torque, generator torque, engine torque and generator brake status. After calculating engine and motor angular accelerations, the strategy will determine the operating mode. Separate subroutines are used for the non-parallel mode (both positive and negative power flow) and the parallel mode to calculate output torque of the gearset. After the output torque of the gearset is computed in either of the separate subroutines, the strategy computes a total wheel torque estimate.

20040730

20070410

20060202

92831.0

G06F1700

NGUYEN, CHUONG P

WHEEL TORQUE ESTIMATION IN A POWERTRAIN FOR A HYBRID ELECTRIC VEHICLE

UNDISCOUNTED

ACCEPTED

G06F

ACCEPTED

AUTOMATIC LIQUID REFILL APPARATUS

An apparatus for maintaining a liquid level within a receptacle such as a Christmas-tree stand water basin or a pet's water dish includes: a) a liquid reservoir adapted to be positioned above a height of a liquid holding basin of the receptacle, where the reservoir includes an open upper end and a lower end, where the open upper end includes a threaded, cylindrical outer surface and the lower end includes a reservoir outlet orifice; b) a cap including a cylindrical wall having an enclosed top end and an open bottom end, where the cylindrical wall includes a threaded inner surface from gauging with a threaded outer surface of the liquid reservoir; c) a valve assembly provided approximate the reservoir outlet orifice of the reservoir and operatively coupled to the cap to open the reservoir outlet orifice when the cap is threaded downwardly on the reservoir to a valve-open height below an actuating height an operative to close the reservoir outlet orifice when the cap is threaded upwardly to a valve-closed height on the reservoir above the actuating height; and d) a circumferential seal provided radially between the reservoir and the cap when the cap is threaded at least between the valve-open height and the valve-closed height.

1. An apparatus for maintaining a liquid level within a receptacle comprising: a liquid reservoir adapted to be positioned above a height of a liquid holding basin of the receptacle, the reservoir including an open upper end and a lower end, the open upper end including a threaded, cylindrical outer surface, and the lower end including an reservoir outlet orifice; a cap including an cylindrical wall having an enclosed top end and an open bottom end, the cylindrical wall including a threaded inner surface for engaging with the threaded outer surface of the liquid reservoir; a valve assembly provided approximate the reservoir outlet orifice of the reservoir and operatively coupled to the cap to open the reservoir outlet orifice when the cap is threaded downwardly on the reservoir to a valve-open height below an actuating height and operative to close the reservoir outlet orifice when the cap is threaded upwardly to a valve-closed height on the reservoir above the actuating height; and a circumferential seal provided radially between the reservoir and the cap when the cap is threaded at least between the valve-open height and the valve-closed height. 2. The apparatus of claim 1, wherein the seal is an o-ring mounted about an outer circumferential surface of the reservoir below the threaded cylindrical outer surface of the reservoir. 3. The apparatus of claim 2, wherein the o-ring is seated within a circumferential groove extending radially inwardly into the outer circumferential surface of the reservoir below the threaded cylindrical outer surface of the reservoir. 4. The apparatus of claim 3, wherein the valve assembly includes a ball-valve. 5. The apparatus of claim 4, wherein the ball-valve includes: a ball positioned below the reservoir outlet orifice of the reservoir and is biased upwardly against the reservoir outlet orifice to close the reservoir outlet orifice; and an actuating structure operatively coupled between the cap and the ball, the actuating structure overcoming the bias to push the ball away from the reservoir outlet orifice when the cap is threaded to the valve-open height. 6. The apparatus of claim 5, wherein the actuating structure includes a rod coupled to an upper end of the ball, extending upwardly through the reservoir outlet orifice and into the reservoir. 7. The apparatus of claim 5, wherein the actuating structure is not attached to the cap so that the cap may be removed from the reservoir leaving the ball to be biased against the reservoir outlet orifice to close the reservoir outlet orifice. 8. The apparatus of claim 5, further comprising a nozzle conduit positioned below the reservoir outlet orifice of the reservoir and containing the ball and bias of the ball-valve therein, the nozzle conduit having a nozzle outlet adapted to be in fluid communication with the receptacle. 9. The apparatus of claim 8, further comprising a hose extending from the nozzle conduit at a first open end and adapted to be extended into the receptacle at an opposing open end. 10. The apparatus of claim 1, wherein the valve assembly includes a ball-valve. 11. The apparatus of claim 10, wherein the ball-valve includes: a ball positioned below the reservoir outlet orifice of the reservoir and is biased upwardly against the reservoir outlet orifice to close the reservoir outlet orifice; and an actuating structure operatively coupled between the cap and the ball, the actuating structure overcoming the bias to push the ball away from the reservoir outlet orifice when the cap is threaded to the valve-open height. 12. The apparatus of claim 11, wherein the actuating structure includes a rod coupled to an upper end of the ball, extending upwardly through the reservoir outlet orifice and into the reservoir. 13. The apparatus of claim 11, wherein the actuating structure is not attached to the cap so that the cap may be removed from the reservoir leaving the ball to be biased against the reservoir outlet orifice to close the reservoir outlet orifice. 14. The apparatus of claim 11, further comprising a nozzle conduit positioned below the reservoir outlet orifice of the reservoir and containing the ball and bias of the ball-valve therein, the nozzle conduit having a nozzle outlet adapted to be in fluid communication with the receptacle. 15. The apparatus of claim 14, further comprising a hose extending from the nozzle conduit at a first open end and adapted to be extended into the receptacle at an opposing open end. 16. The apparatus of claim 1, wherein the valve assembly is operative to maintain the reservoir outlet orifice closed when the cap is threaded upwardly beyond the valve-closed height and removed from the reservoir. 17. An apparatus for maintaining a liquid level within a receptacle comprising: a liquid reservoir adapted to be positioned above a height of a liquid holding basin of the receptacle, the reservoir including an open upper end and a lower end, the open upper end including an outer surface, and the lower end including an reservoir outlet orifice; a cap including an outer wall having an enclosed top end and an open bottom end, the outer wall shaped to engage with the outer surface of the liquid reservoir; a valve assembly provided approximate the reservoir outlet orifice of the reservoir and operatively coupled to the cap to open the reservoir outlet orifice when the cap is moved downwardly on the reservoir to a valve-open height below an actuating height and operative to close the reservoir outlet orifice when the cap is moved upwardly to a valve-closed height on the reservoir above the actuating height; and a peripheral seal provided between the outer surface of the reservoir and an inner surface of the outer wall of the cap when the cap is moved at least between the valve-open height and the valve-closed height.

BACKGROUND OF INVENTION The present invention is directed to an automatic liquid refill apparatus for maintaining a liquid level within a receptacle such as a water basin in a Christmas tree stand or in a pet's water dish; and, more specifically a vacuum break automatic gravity flow liquid refill apparatus having relatively simple on/off actuation mechanism as well as the ability for the liquid storage/supply reservoir to be refilled without flooding the refill receptacle. SUMMARY OF INVENTION A first aspect of the present invention is directed to an apparatus for maintaining a liquid level within a receptacle that includes: a) a liquid reservoir adapted to be positioned above a height of a liquid holding basin of the receptacle, where the reservoir includes an open upper end and a lower end, where the open upper end includes a threaded, cylindrical outer surface and the lower end includes a reservoir outlet orifice; b) a cap including a cylindrical wall having an enclosed top end and an open bottom end, where the cylindrical wall includes a threaded inner surface from gauging with a threaded outer surface of the liquid reservoir; c) a valve assembly provided approximate the reservoir outlet orifice of the reservoir and operatively coupled to the cap to open the reservoir outlet orifice when the cap is threaded downwardly on the reservoir to a valve-open height below an actuating height an operative to close the reservoir outlet orifice when the cap is threaded upwardly to a valve-closed height on the reservoir above the actuating height; and d) a circumferential seal provided radially between the reservoir and the cap when the cap is threaded at least between the valve-open height and the valve-closed height. In a more detailed embodiment, the seal is an o-ring mounted about an outer circumferential surface of the reservoir below the threaded cylindrical outer surface of the reservoir. In a further detailed embodiment, the o-ring is seated within a circumferential groove extending radially inwardly into the outer circumferential surface of the reservoir, below the threaded cylindrical outer surface of the reservoir. In yet a further detailed embodiment, the valve assembly includes a ball-valve. In yet a further detailed embodiment, the ball-valve includes a ball positioned below the reservoir outlet orifice of the reservoir and is biased upwardly against the reservoir outlet orifice to close the reservoir outlet orifice, and includes an actuating structure operatively coupled between the cap and the ball, where the actuating structure overcomes the bias to push the ball away from the reservoir outlet orifice when the cap is threaded to the valve-open height. In yet a further detailed embodiment, the actuating structure includes a rod coupled to an upper end of the ball, extending upwardly through the reservoir outlet orifice and then into the reservoir. Alternatively, the actuating structure is not attached to the cap so that the cap may be removed from the reservoir, leaving the ball to be biased against the reservoir outlet orifice to thereby close the reservoir outlet orifice. Alternatively, the apparatus further includes e) a nozzle conduit position below the reservoir outlet orifice of the reservoir and contain the ball and bias means of the ball-valve therein, where the nozzle conduit has a nozzle outlet adapted to be in fluid communication with the receptacle. In an alternative detailed embodiment of the first aspect of the present invention, the valve assembly includes a ball valve. In a further detailed embodiment, the ball valve includes a ball positioned below the reservoir outlet orifice of the reservoir and is biased upwardly against the reservoir outlet orifice to close the reservoir outlet orifice, and includes an actuating structure operatively coupled between the cap and the ball, where the actuating structure overcomes the bias to push the ball away from the reservoir outlet orifice when the cap is threaded to the valve-open height. In a more detailed embodiment, the actuating structure includes a rod coupled to an upper end of the ball, extending upwardly through the reservoir outlet orifice and into the reservoir. Alternatively, the actuating structure is not attached to the cap so that the cap may be removed from the reservoir leaving the ball to be biased against the reservoir outlet orifice to close the reservoir outlet orifice. Alternatively, the apparatus further includes e) a nozzle conduit positioned below the reservoir outlet orifice of the reservoir and containing the ball and bias mechanism of the ball-valve therein, where the nozzle conduit has a nozzle outlet adapted to be in fluid communication with the receptacle. In this alternative detailed embodiment, the apparatus may further include f) a hose extending from the nozzle conduit at a first open end and adapted to be extended into the receptacle at an opposing end. In yet a further alternative detailed embodiment of the first aspect of the present invention, the valve assembly is operative to maintain the reservoir outlet orifice closed when the cap is threaded upwardly beyond the valve-closed height and removed from the reservoir. It is a second aspect of the present invention to provide an apparatus for maintaining a liquid level within a receptacle that includes a) a liquid reservoir adapted to be positioned above a height of a liquid-holding basin of the receptacle, where the reservoir includes an open upper end and a lower end, where the open upper end includes an outer surface and the lower end includes a reservoir outlet orifice; b) a cap including an outer wall having an enclosed top end and an open bottom end, where the outer wall is shaped to engage with the outer surface of the liquid reservoir; c) a valve assembly provided approximate the reservoir outlet orifice of the reservoir and operatively coupled to the cap to open the reservoir outlet orifice when the cap is moved downwardly on the reservoir to a valve-open height below an actuating height and operative to close the reservoir outlet orifice when the cap is moved upwardly to a valve-closed height on a reservoir above the actuating height; and d) a peripheral seal provided between the outer surface of the reservoir and an inner surface of the outer wall of the cap when the cap is moved at least between the valve-open height and the valve-closed height. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic/cross-sectional depiction of an exemplary embodiment of the present invention illustrating the liquid-holding reservoir assembly in a nozzle-valve open configuration; FIG. 2 illustrates the exemplary embodiment of FIG. 1 where the liquid-holding reservoir assembly is in a nozzle-valve closed configuration; and FIG. 3 illustrates the exemplary embodiment of FIGS. 1 and 2 in which the liquid-holding reservoir assembly is in the nozzle-valve closed configuration with the reservoir cap removed to allow refill of the liquid-holding reservoir. DETAILED DESCRIPTION The present invention is directed to an automatic liquid refill apparatus for maintaining a liquid level within a receptacle such as a water basin in a Christmas tree stand or in a pet's water dish; and, more specifically a vacuum break automatic gravity flow liquid refill apparatus having relatively simple on/off actuation mechanism as well as the ability for the liquid storage/supply reservoir to be refilled without flooding the refill receptacle. As shown in FIG. 1, an exemplary embodiment of an automatic liquid refill apparatus 10 according to the present invention for maintaining a liquid level 12 in a refill receptacle 14, such as a water basin in a Christmas tree stand or in a pet's water dish, includes a liquid-holding reservoir assembly 16 positioned at a height above the desired water level 12 of the refill receptacle 14, where the liquid-holding reservoir assembly 16 includes an outlet nozzle 18 having a hose 20 extending therefrom for being coupled in an inlet port 22 of the refill receptacle 14. The liquid-holding reservoir assembly includes a substantially cylindrical primary reservoir 24 and a substantially cylindrical nozzle conduit 26 positioned below the primary reservoir and in fluid communication with the primary reservoir, and a reservoir cap 28 threaded onto the upper open end 30 of the primary reservoir 24. The open upper end 30 of the primary reservoir 24 includes threads 32 on the outer circumferential surface thereof for engaging with corresponding threads 34 on the inner circumferential surface under the reservoir cap 28. The cylindrical wall 36 of the reservoir cap has a portion 38 extending below the threads 34 having an inner surface that is adapted to engage with a circumferential seal 40 provided on the outer circumferential surface of the primary reservoir 24 below the threads 32 of the primary reservoir. The circumferential seal 40 includes an o-ring 42 received within an annular notch 43 extending radially into the outer circumferential surface of the primary reservoir 24. The nozzle conduit 26 extending below the primary reservoir 24 includes a ball-valve assembly 44 mounted therein, where the ball-valve assembly 44 includes a ball-valve 46 biased towards an outlet orifice 48 of the primary reservoir 24 by a spring 50, which is mounted between a base 52 and the ball valve 46 within the nozzle conduit 26. The base 52 includes axial channels to allow the liquid to pass thereby. The ball valve assembly 44 also includes an actuating rod 54 coupled to, and extending from the ball valve 46 upwardly through the outlet orifice 48 of the primary reservoir and abutting against (but not necessarily coupled to) the top inner surface 56 of the reservoir cap 28 when the reservoir cap is threaded onto the open upper end 30 of the primary reservoir 24. As shown in FIG. 1, the reservoir cap 28 is threaded downwardly onto the open upper end 30 of the primary reservoir 24 so that the inner top surface 56 of the reservoir cap 28 pushes downwardly on the actuator rod 54 of the ball valve assembly 44, which in turn, pushes downwardly on the ball valve 46 of the ball valve assembly 44, overcoming the bias induced by the spring 50, to thereby open the outlet orifice 48 of the primary reservoir and to allow fluid communication between the primary reservoir 24, the nozzle conduit 26, the hose 20 and the refill receptacle 14. In this valve-open configuration, the liquid-holding reservoir assembly 16 operates as a vacuum break, gravity regulated liquid delivery system. Such vacuum break systems require that the source reservoir (i.e., the primary reservoir 24 in the present embodiment) be substantially airtight. In the present embodiment, the circumferential seal 40 provided radially between the cylindrical wall 36 of the reservoir cap 28 and the outer circumferential surface of the primary reservoir 24 provides this substantial airtight seal. A partial vacuum develops in the primary reservoir 24 which stops the flow of water through the liquid-holding reservoir assembly 16 and into the liquid receptacle 14 until the liquid level 12 within the liquid receptacle 14 drops below the level of the inlet port 22, which allows air to enter into the inlet port 22. This allowance of air into the inlet port 22 and reservoir assembly 16 relieves the partial vacuum within the reservoir assembly 16 and allows the liquid to flow downwardly through the reservoir assembly 16 and back into the refill receptacle 14 until the level of liquid within the refill receptacle 14 reaches above the level of the inlet port 22 again. This automatic refill process will proceed continuously until the liquid-holding reservoir assembly 16 is emptied or until the ball valve assembly 44 is moved to a closed position, as described below. As shown in FIG. 2, the reservoir cap 28 has been threaded counter-clockwise so that it lifts upwardly with respect to the primary reservoir 24, which in turn allows the actuating rod to be pushed upwardly by the spring 50 until the ball valve is pressed against the outlet orifice 48 of the primary reservoir 24, thereby closing the outlet orifice 48. In the present embodiment, as can be seen in FIG. 2, the portion 38 of the outer cylindrical wall 36 of the reservoir cap 28 extending below the threads 34 is still engaged with the circumferential seal 40 so that the partial vacuum provided within the liquid-holding reservoir assembly 16 still exists when the liquid-holding reservoir assembly is configured to the valve-closed configuration as shown in FIG. 2. In this configuration, the automatic refill operation of the apparatus 10 will cease until the valve assembly 44 is opened again. As shown in FIG. 3, further counter-clockwise threading of the reservoir cap 28 will allow the reservoir cap 28 to be removed from the open upper end 30 of the primary reservoir 24. Because the ball valve 46 is still biased against the outlet orifice 48 by the spring 50 of the ball valve assembly 44, the ball valve assembly 44 will still be closed when the reservoir cap 28 is removed. This allows the primary reservoir 24 to be refilled or capped off without risking flooding into the refill receptacle 14. Selection of the dimensions and other configurations for the exemplary embodiment are based upon reference to “Water Conveyance with Siphons”, September 2000, Canadian Prairie Farm Rehabilitation Administration, Agriculture and Agri-Food, Canada, the disclosure of which is incorporated herein by reference. Based upon the above description, it can be seen that the exemplary embodiment allows the valve assembly of the liquid-holding reservoir assembly to the opened and closed by mere movement of the reservoir cap 28 up and down on the open upper end 30 of the primary reservoir 24, while maintaining a circumferential seal between the reservoir cap 28 and the primary reservoir 24 during this movement. Additionally, the cooperation between the reservoir cap and the valve assembly assures that the valve assembly is closed when the reservoir cap is removed, thereby allowing refill or capping-off of the primary reservoir 24 without risking flooding into the refill receptacle 14. Following from the above description and invention summaries, it should be apparent to those of ordinary skill in the art that, while the apparatuses herein described and illustrated constitute exemplary embodiments of the present invention, it is understood that the inventions are not limited to these precise embodiments and that changes may be made therein without departing from the scope of the inventions as defined by the claims. For example, and without limitation, it is not necessary that the valve assembly described herein be a ball-valve assembly and it is also not necessary that the operative coupling between the reservoir cap and the ball-valve assembly be an actuating rod. Furthermore, and without limitation, it is not necessary that the reservoir cap be threaded onto the primary reservoir. Additionally, it is to be understood that the inventions are defined by the claims and it is not intended that any limitations or elements describing the exemplary embodiments set forth herein are to be incorporated into the meanings of the claims unless explicitly recited in the claims themselves. Likewise, it is to be understood that it is not necessary to meet any or all of the recited advantages or objects of the inventions disclosed herein in order to fall within the scope of any claim, since the inventions are defined by the claims and since inherent and/or unforeseen advantages of the present inventions may exist even though they may not have been explicitly discussed herein.

<SOH> BACKGROUND OF INVENTION <EOH>The present invention is directed to an automatic liquid refill apparatus for maintaining a liquid level within a receptacle such as a water basin in a Christmas tree stand or in a pet's water dish; and, more specifically a vacuum break automatic gravity flow liquid refill apparatus having relatively simple on/off actuation mechanism as well as the ability for the liquid storage/supply reservoir to be refilled without flooding the refill receptacle.

<SOH> SUMMARY OF INVENTION <EOH>A first aspect of the present invention is directed to an apparatus for maintaining a liquid level within a receptacle that includes: a) a liquid reservoir adapted to be positioned above a height of a liquid holding basin of the receptacle, where the reservoir includes an open upper end and a lower end, where the open upper end includes a threaded, cylindrical outer surface and the lower end includes a reservoir outlet orifice; b) a cap including a cylindrical wall having an enclosed top end and an open bottom end, where the cylindrical wall includes a threaded inner surface from gauging with a threaded outer surface of the liquid reservoir; c) a valve assembly provided approximate the reservoir outlet orifice of the reservoir and operatively coupled to the cap to open the reservoir outlet orifice when the cap is threaded downwardly on the reservoir to a valve-open height below an actuating height an operative to close the reservoir outlet orifice when the cap is threaded upwardly to a valve-closed height on the reservoir above the actuating height; and d) a circumferential seal provided radially between the reservoir and the cap when the cap is threaded at least between the valve-open height and the valve-closed height. In a more detailed embodiment, the seal is an o-ring mounted about an outer circumferential surface of the reservoir below the threaded cylindrical outer surface of the reservoir. In a further detailed embodiment, the o-ring is seated within a circumferential groove extending radially inwardly into the outer circumferential surface of the reservoir, below the threaded cylindrical outer surface of the reservoir. In yet a further detailed embodiment, the valve assembly includes a ball-valve. In yet a further detailed embodiment, the ball-valve includes a ball positioned below the reservoir outlet orifice of the reservoir and is biased upwardly against the reservoir outlet orifice to close the reservoir outlet orifice, and includes an actuating structure operatively coupled between the cap and the ball, where the actuating structure overcomes the bias to push the ball away from the reservoir outlet orifice when the cap is threaded to the valve-open height. In yet a further detailed embodiment, the actuating structure includes a rod coupled to an upper end of the ball, extending upwardly through the reservoir outlet orifice and then into the reservoir. Alternatively, the actuating structure is not attached to the cap so that the cap may be removed from the reservoir, leaving the ball to be biased against the reservoir outlet orifice to thereby close the reservoir outlet orifice. Alternatively, the apparatus further includes e) a nozzle conduit position below the reservoir outlet orifice of the reservoir and contain the ball and bias means of the ball-valve therein, where the nozzle conduit has a nozzle outlet adapted to be in fluid communication with the receptacle. In an alternative detailed embodiment of the first aspect of the present invention, the valve assembly includes a ball valve. In a further detailed embodiment, the ball valve includes a ball positioned below the reservoir outlet orifice of the reservoir and is biased upwardly against the reservoir outlet orifice to close the reservoir outlet orifice, and includes an actuating structure operatively coupled between the cap and the ball, where the actuating structure overcomes the bias to push the ball away from the reservoir outlet orifice when the cap is threaded to the valve-open height. In a more detailed embodiment, the actuating structure includes a rod coupled to an upper end of the ball, extending upwardly through the reservoir outlet orifice and into the reservoir. Alternatively, the actuating structure is not attached to the cap so that the cap may be removed from the reservoir leaving the ball to be biased against the reservoir outlet orifice to close the reservoir outlet orifice. Alternatively, the apparatus further includes e) a nozzle conduit positioned below the reservoir outlet orifice of the reservoir and containing the ball and bias mechanism of the ball-valve therein, where the nozzle conduit has a nozzle outlet adapted to be in fluid communication with the receptacle. In this alternative detailed embodiment, the apparatus may further include f) a hose extending from the nozzle conduit at a first open end and adapted to be extended into the receptacle at an opposing end. In yet a further alternative detailed embodiment of the first aspect of the present invention, the valve assembly is operative to maintain the reservoir outlet orifice closed when the cap is threaded upwardly beyond the valve-closed height and removed from the reservoir. It is a second aspect of the present invention to provide an apparatus for maintaining a liquid level within a receptacle that includes a) a liquid reservoir adapted to be positioned above a height of a liquid-holding basin of the receptacle, where the reservoir includes an open upper end and a lower end, where the open upper end includes an outer surface and the lower end includes a reservoir outlet orifice; b) a cap including an outer wall having an enclosed top end and an open bottom end, where the outer wall is shaped to engage with the outer surface of the liquid reservoir; c) a valve assembly provided approximate the reservoir outlet orifice of the reservoir and operatively coupled to the cap to open the reservoir outlet orifice when the cap is moved downwardly on the reservoir to a valve-open height below an actuating height and operative to close the reservoir outlet orifice when the cap is moved upwardly to a valve-closed height on a reservoir above the actuating height; and d) a peripheral seal provided between the outer surface of the reservoir and an inner surface of the outer wall of the cap when the cap is moved at least between the valve-open height and the valve-closed height.

20040805

20060801

20060209

65183.0

B65B130

MAUST, TIMOTHY LEWIS

AUTOMATIC LIQUID REFILL APPARATUS

SMALL

ACCEPTED

B65B

ACCEPTED

Document placemarker

A method of saving and retrieving a selected string on an HTML-based document. A cursor is placed at a location on the document. The number of HTML tags are counted between the beginning of the document and the position of the cursor. The count of HTML tags is saved in association with the URL of the document. When the document at the URL is retrieved at a later time, the string at the location of the previously set cursor is retrieved and communicated to the end user.

1. A method of marking the position of a string in a document comprising the steps of: retrieving the document, establishing a cursor location in the document associated with the beginning of the string, parsing the source HTML in the document for a positional value representative of the number of HTML tags prior to the cursor location, identifying the URL of the document, and storing the positional value and the URL on a computer accessible medium. 2. The method of claim 1 further comprising the steps of: requesting the document associated with the URL, retrieving the positional value and URL from the computer accessible medium, parsing the source HTML in the document until the quantity of tags parsed equals the positional value, and outputting the string at the cursor location. 3. The method of claim 2 wherein the step of outputting the string is executed by an output means selected from the group consisting of a speech synthesizer, a Braille reader, a screen magnification application, and a pop-up display window. 4. A method of marking the position of a string in a document comprising the steps of: retrieving the document, establishing a cursor location in the document associated with the beginning of the string, parsing the source HTML in the document for a positional value representative of the number of HTML tags prior to the cursor location, identifying the URL of the document, storing the positional value and the URL on a computer accessible medium requesting the document associated with the URL, retrieving the positional value for the URL from the computer accessible medium, parsing the source HTML in the document until the quantity of tags parsed equals the positional value, and outputting the string by an output means selected from the group consisting of a speech synthesizer, a Braille reader, a screen magnification application, and a pop-up display window. 5. A method of claim 4 further comprising the step of outputting the string responsive to navigation to the associated URL. 6. The method of claim 4 further comprising step of storing a position for an entire domain whereby common headers that propagate across an entire domain are bypassed so that output begins at a location in the HTML that is distinct between web pages in the domain. 7. A method of marking the position of a string in a webpage comprising the steps of: retrieving a webpage, establishing a cursor location in the webpage associated with the beginning of the dynamically changing string, parsing the source HTML in the webpage for a positional value representative of the number of HTML tags prior to the cursor location, identifying the URL of the webpage, storing the positional value and the URL on a computer accessible medium retrieving the positional value and URL from the computer accessible medium, requesting the webpage associated with the URL, responsive to requesting the webpage associated with the URL, automatically parsing the source HTML in the webpage until the quantity of tags parsed equals the positional value, and automatically outputting the string by an output means selected from the group consisting of a speech synthesizer, a Braille reader, a screen magnification application, and a pop-up display window.

CROSS REFERENCE TO RELATED APPLICATION This application claims priority to U.S. Provisional Patent Application Ser. No. 60/493,707 filed Aug. 8, 2003 entitled “Method and apparatus for adding Placemarkers to a computer display.” The specification and claims of U.S. Provisional Patent Application Ser. No. 60/493,707 are incorporated herein by reference. FIELD OF INVENTION This invention relates to data processing and more specifically to accessing, locating and collecting data from a predetermined position in a document. BACKGROUND OF INVENTION During the infancy of the World Wide Web (herein “the Web”), documents transferred via hypertext protocol (“HTTP”) were frequently static and unchanging over long periods of time. However, as the web evolved, website were more frequently updated and linked to live databases. These new websites became dynamic, changing their displayed output as the linked database was updated. In most cases, database driven web sites maintained a consistent appearance. The tables, colors, fonts and other layout and formatting options were the same. However, the information placed within the layouts would change. Modern development tools such as Microsoft's ASP.NET provides tools to rapidly construct web pages dynamically linked to backend databases. For the average web users, viewing dynamic data is a convenience. Users check changing stock prices, sports scores, headlines, weather conditions and the like. In addition, many valuable databases are placed online so that anonymous users have limited access to their resources. The end user must type in a query in a web form which is then assembled into a query string. A SQL string is constructed from the information on the web form and the results are displayed. Sophisticated users and programmers sometimes write applications that “mine” a publicly accessible database to collect the contents of the database for their own use. Although some may question the ethics or legality of such database mining, it is important to note the underlying technology is known as “screen scraping.” In other words, the software application uses complex string handling routines to locate dynamically changing data on a website and store the results. Screen scraping has existed well before the advent of the web. Many terminal modes such as 3270, used to connect to mainframes, were “scraped” of data at predetermined locations on the display screen. To develop such a screen scraping application for the web a programmer will typically examine the HTML source code of the web page near the data element sought to be mined. The programmer will find a string of alphanumeric characters that consistently appears next to the target data element and use that string as a reference point. For example, if an HTML tag calls for a table cell to be a certain background color, the programmer may have the application look for that tag, go three lines down, twenty characters across and copy the next ten characters to a database field. A drawback of this method is that the author of the web page may change the page layout whereby the reference point is no longer valid. For users with full vision, finding dynamically changing data is typically not a problem. Web sites designers attempt to display the information in a format easy to assimilate. However, visually impaired (also known as “low-vision”) users often have difficultly finding a particular portion of a web page. While screen readers assist the visually impaired user by reading the output of a web page, a low-vision user may only want to hear about certain dynamically changing data on a web page. For example, a screen reader on a financial website may take a couple minutes to read the content between the top of the page and the current value of the Dow Jones Industrial Average (the “Dow”). A low-vision user may want to periodically check the Dow to see if the applicable stocks are going up or down for the day. It would be cumbersome to force the user to listen to other content on the page when all he or she wants to know about is the current value of the Dow. Although this information could be “scraped” by examining the HTML source code, writing a custom application for each individual website would also be cumbersome for the low-vision user. As a user moves though an HTML document downloaded from the Internet with a screen reader, he may want to return to a previously read portion of the document. Unfortunately, currently available screen readers do not provide the capability to return to a specified place within the document, such as a word or line. Instead, the user must return to the beginning of the document and search for the desired location. Therefore, it would be desirable to provide a capability to mark the text of a HTML document with a tag and to be able return to the tagged portion of the text in the future upon demand. What is needed is a method to locate where dynamically changing information appears on a web page whereby a screen reader can quickly provide the information to the low-vision user. Another need in the art is for a method of finding the location of this information without requiring the end user to engaging in complex string handing routines. SUMMARY OF INVENTION The present invention includes a screen reader that provides access to both software applications and the Internet. The screen reader includes a speech synthesizer that operates with a sound card in a personal computer to read aloud information appearing upon the computer screen. The screen reader provides access to a wide variety of software applications. The reader includes an interface that provides output to refreshable Braille displays. The screen reader has two cursors available to assist the user when using an application in the operating system, the PC cursor and the screen reader cursor The PC cursor is linked to the keyboard functions of the software applications and is used when typing information, moving through options in dialog boxes and making a selection of a particular option. Thus, as each key is pressed, the speech synthesizer recites the letter corresponding to the key or the name of the selected option. The screen reader cursor is linked to mouse pointer functions in the software applications to provide access to information in an application window that is beyond the scope of the PC cursor. For example, as the user maneuvers the mouse pointer over a tool bar, the speech synthesizer recites the name of the particular toolbar button that the pointer is over. In addition, the screen reader supports web browsers with special features such as link lists, frame lists, forms mode and reading of HTML labels and graphic labels included on web pages. Upon entering an HTML document via a URL, the screen reader actuates a virtual cursor that mimics the functions of the PC cursor. The virtual cursor causes the speech synthesizer to speak the number of frames in a document displayed upon the monitor screen and the number of links in the frame currently being displayed. In addition, the speech synthesizer reads graphics labeled by alternate tags in the HTML code. An embodiment of the present invention includes a method of marking the position of a dynamically changing string in a document including the steps of retrieving the document, establishing a cursor location in the document associated with the beginning of the dynamically changing string, parsing the source HTML in the document for a positional value representative of the number of HTML tags prior to the cursor location, identifying the URL of the document, and storing the value and the URL on a computer accessible medium. Additional steps include retrieving the positional value and URL from the computer accessible medium, requesting the document associated with the URL, parsing the source HTML in the document until the quantity of tags parsed equals the positional value, and outputting the dynamically changing string at the cursor location. The step of outputting the dynamically changing string at the cursor location may be executed by an output means selected from the group consisting of a speech synthesizer, a Braille reader, a screen magnification application, and a pop-up display window. Outputting the dynamically changing string may be performed responsive to navigation to the associated URL. A position for an entire domain may also be stored whereby common headers that propagate across an entire domain are bypassed so that the cursor is positioned at content that is distinct between web pages in the domain. BRIEF DESCRIPTION OF THE DRAWINGS For a fuller understanding of the invention, reference should be made to the following detailed description, taken in connection with the accompanying drawings, in which: FIG. 1 is a schematic diagram illustrating the present invention as applied to a personal computer connected to the Internet. FIG. 2 is a flow chart illustrating the operation of the personal computer shown in FIG. 1. FIG. 3 is a flow chart illustrating placement of a temporary Placemarker in accordance with the invention. FIG. 4 is a flow chart illustrating selection of a fixed Placemarker in accordance with the invention. FIG. 5 illustrates a monitor screen display utilized by the flow chart shown in FIG. 4. FIG. 6 is a flow chart illustrating placement of a fixed Placemarker and other operations available in accordance with the invention. FIG. 7 illustrates a monitor screen display for adding a Placemarker that is utilized by the flow chart shown in FIG. 6. FIG. 8 illustrates a monitor screen display for changing a Placemarker name that is utilized by the flow chart shown in FIG. 6. FIG. 9 is a flow chart illustrating a quick navigation feature that is included in the invention. FIG. 10 is a flow chart illustrating another quick navigation feature that is included in the invention. FIG. 11 is a view of a typical screen reader hardware configuration used by individuals. FIG. 12 is a web page display showing two dynamically changing stock prices. FIG. 13 shows underlying HTML source code for the web page of FIG. 12. FIG. 14 shows a dialog box for personalizing settings according to an embodiment of the invention. FIG. 15 is a flow chart illustrating the execution of the Placemarkers responsive to the navigation to a URL having preset Placemarkers. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention is directed toward a method and apparatus used in conjunction with screen reading software, such as the JAWS® screen reader, available from Freedom Scientific, for providing text markers for a document obtained from an outside source, such as, for example, the Internet. These text markers are referred to as “Placemarkers” in the following description. The Placemarkers are relative locations in a virtual document that corresponds to the original document. The virtual document and virtual PC cursor are driven by a virtual buffer—a textual representation of what appears on a web page. The virtual buffer is created by parsing the HTML of the page and then generating text that both describes the page in terms of headings, tables, etc. and which flattens items such as multicolumn text. What ends up in the virtual buffer is the equivalent of what a human would read aloud when asked to read a web page to a blind person. For every character of the text in the virtual buffer, a pointer back to the inner-most HTML element is maintained that encloses it. These pointers are in a parallel array to the array of text. From that HTML element it is possible to query both its siblings and its parent. This allows the application to move from any element of an HTML document to any other. For example, when using Microsoft Internet Explorer, a user clicks a location on the screen. The JAWS® application calls the Microsoft supplied ElementFromPoint function to find the inner-most HTML element that encloses the character clicked. The application then looks for this element in the array of elements described above, and moves the cursor in the virtual buffer to the first enclosed character of that element. The Placemarkers are stored in a separate Placemarker file, such as in a user's personal computer. The Placemarkers remain unknown to the outside source of the document being read, but are known to the screen reading software. The Placemarkers are stored using document structural information which is known to the screen reading software. While the following description refers to use with personal computers, it will be appreciated the invention also may be practiced with other similar devices, such as, for example, PAC Mate, a personal data assistant for the visually impaired. Referring now to the drawings, there is shown in FIG. 1, a workplace or home computer installation 10 with a personal computer 11 connected by conventional access hardware to the Internet 12. The personal computer is equipped with screen reading software, such as the JAWS® screen reader. A flow chart illustrating the operation of the present invention is shown in FIG. 2. Following connection to the Internet 12, the computer user can download material, such as a document 13 from the Internet. The document 13 is displayed upon the computer monitor screen. The downloading of the document 13 is shown in functional block 14 of FIG. 2. The JAWS® screen reader is operative to parse the document 13 in functional block 14 of FIG. 2 to locate any hidden and/or embedded markup tags. Such tags are commonly used by HTML, XML. Java Script and other embedded scripts when the original source documents are created. Following the parsing, JAWS® screen reader then creates a virtual document 16 in functional block 17 that corresponds to the original source document, but has available the embedded tags to aid in navigating the virtual document 16. The virtual document 16 referred to above is a document hosted by an application that does not in and of itself use a visible caret, but does enable usage of the common navigation keys found in Word Processors, such as the arrow keys and combinations of keys with control, alt or shift. Neither the original document, such as, for example, a web page, nor the host application, such as Internet Explorer, are virtual. The JAWS® screen reader also creates a virtual cursor as a soft cursor that is used by the software for navigation purposes within the virtual document, as explained earlier in this document. Besides the standard navigation and selection commands, the virtual cursor also provides many features that aid quicker navigation and contextual exploration. The present invention contemplates adding Placemarkers as another such feature. All of the features associated with the virtual cursor allow navigation (Move To) either on a single keystroke or by selecting the desired item from a list. Except for the Placemarkers, the features depend on the existence of corresponding elements within the Virtual Document for user benefit. Returning to FIG. 2, the present invention contemplates assigning Placemarkers within the virtual document 16 in functional block 18. The invention further contemplates that the Placemarkers are associated with the embedded document tags. Because the Placemarkers are keyed to the architecture of the document, they are independent of the document text. Additionally, fixed Placemarkers are saved in functional block 19 to a separate file 20 shown in FIG. 1 that corresponds to the document in order to preserve the Placemarkers for future use. Unlike other previously developed features of the Virtual Cursor, Placemarkers creates an environment in which the user can define, change, rename and remove new or existing locations, themselves called Placemarkers, for the active Virtual document. The present invention contemplates that in most, if not all cases, the Virtual Document is accessed (read and interacted with, in the case of a form), but the document is not modified by the user. Thus, while the Virtual Document's content may change at any time, the structure remains the same and the Placemarkers are not effected by the changes. The Placemarkers are quite different from prior art bookmarks, which are created by the user or developer of a document under an assumption that the document will not change structurally or in content without the bookmark's creator knowledge. With regard to a Placemarker, the Placemarker user not be aware of when the Virtual document changed or what changed. For example, in a Word Processor, Bookmarks can be used to create a Table of Contents, where the author/document developer is thoroughly aware of the document's structure and content. For a Placemarker user, the Virtual Document is one means by which to gather information that may be updated frequently, such as favorite sports scores, TV guide or latest specials. With conventional Bookmarks in a word processor, the bookmark is stored in the document or another file known to the word processor itself. With Placemarkers, the Virtual Document's host application does not have any information concerning the Placemarkers unless that Placemarker is specifically designed to activate a script or command within the document or application. In order to understand the significance of this difference, the Placemarker is compared it to a feature found in the average word processor, and one found in the average web browser, with the differences highlighted. With respect to a web browsing application, the bookmark points to a specific document, or location in document. In most cases, the bookmark points to a specific document via Uniform Resource Locator (URL) as prescribed by the developer of the web site. When the bookmark points to a location within a document, it is through the same method, using a URL. In contrast, the Placemarker, although usable on the Internet, points to a structural location within a page or any series of pages on the same web site. For example, if there is a blue box on every page of a given web site with new information, this spot can be marked once and the Placemarker will locate the same blue box on all the pages located at the site where it is found. This is true even if the content in the box changes as the user explores the web site. Thus, the Placemarker is by definition a location, structural or otherwise, defined and accessed by associated screen reader software, such as JAWS®. The host application of the Virtual Document has no relationship with the Placemarker. Unless the screen reader user is the developer of the web site or other Virtual Document, the document's creator, whether human or computer generated, there is no relationship between the document creator and the Placemarker itself. The invention contemplates that Placemarker usage includes structural locations in the Virtual document where important information is updated, either interactively by the user (form and input controls in document), or automatically without the user's knowledge. The invention also contemplates that users of Placemarkers will have the opportunity to copy and share Placemarker files which pertain to specific documents or web sites. The present invention contemplates providing Placemarkers that would allow the user of a screen reader to designate a place in a document line of text or a portion of a screen for future access. The invention further contemplates two types of Placemarkers, fixed and temporary. Referring again to the drawings, there is illustrated in FIG. 3, a flow chart for an algorithm for inserting a temporary Placemarker in a HTML document that is in accordance with the invention. The algorithm is entered through box 21 when the user simultaneously depresses the CTRL and K keys on his keyboard. In response, the algorithm inserts a temporary marker in a JAWS®) file that corresponds to the current location of the Virtual PC Cursor, as shown in functional box 22. Thus, the Placemarker of the present invention differs from conventional text bookmarks, such as in Microsoft Word®, in that the user can return to the marked position even if the data on the page has been changed. Also, by utilizing the Virtual PC Cursor, the user can insert Placemarkers into documents that do not have a keyboard accessible cursor, such as a flashing vertical line. The algorithm then advances to functional block 23 where the temporary Placemarker is added to a list of Placemarker names, that will be described below, under the name “Temporary”. The user can then return to the location of the temporary Placemarker, as also will be explained below. The temporary Placemarker is maintained as long as the user remains upon the current page. Hence, the algorithm advances to decision block 24 where it is determined whether the user is still on the same page. If the user has moved to another page, the algorithm transfers to functional block 25 where the temporary Placemarker is removed from the previous document page. The algorithm continues to functional block 26 where the “Temporary” name is deleted from the list of Placemarker names. Once deleted, the temporary Placemarker will not be present should the user return to the previously viewed page of the document. The algorithm then ends by passing through exit block 27. If, in decision block 24, the algorithm determines that the user is still on the same page, the algorithm transfers to decision block 28. In decision block 28, the algorithm determines whether the user has depressed the CTRL and K keys a second time. If the user has depressed the CTRL and K keys a second time, the algorithm transfers to functional block 29 and moves the temporary Placemarker to the current location of the Virtual PC Cursor. The algorithm then returns to decision block 24 to again check as to whether the user is still on the same page of the document. If, in decision block 28, the user has not depressed the CTRL and K keys a second time, the algorithm simply returns to decision block 24 to again check as to whether the user is still on the same page of the document. As long as the user remains on the same page, the temporary Placemarker will again be moved to the current location of the Virtual PC Cursor each subsequent time the CTRL and K keys are depressed. As indicated above, the invention also contemplates inserting fixed Placemarkers into a HTML document. Referring again to the drawings, there is illustrated in FIG. 4, a flow chart for an algorithm for inserting a such a fixed Placemarker that is in accordance with the invention. The algorithm is entered through box 30 when the user simultaneously depresses the CTRL, SHIFT and K keys on his keyboard. In response, the algorithm advances to functional block 32 where a “Placemarker List” dialog screen as shown in FIG. 5 is opened. The dialog screen includes a plurality of command buttons that will be described below and also displays the current list of named Placemarkers, as illustrated in FIG. 5. If there are no current Placemarkers, the name display will be blank and user may proceed to use the buttons, as will be described below. If there are current Placemarkers, the last one added or used will be highlighted. The algorithm advances to functional block 34 where the JAWS® speech synthesizer reads the highlighted Placemarker name. The algorithm then advances to decision block 36 where the user decides whether the highlighted Placemarker name is acceptable. If the name is acceptable, the user continues through the transfer point labeled “A” to the flow chart shown in FIG. 6. If the highlighted Placemarker name is not acceptable, the invention allows the user to shift up or down the list of current Placemarker names to find the desired one. Accordingly, the algorithm advances to decision block 38 where the user decides whether he wants to shift down the list. If the user wants to shift down the list, he presses the down arrow key on his keyboard, as shown in functional block 40. In response to the down arrow keystroke, the algorithm moves the highlight down to the next listed Placemarker name in functional block 42. The algorithm then advances to functional block 44 where the JAWS® speech synthesizer reads the newly highlighted Placemarker name. The algorithm then advances to decision block 46 where the user decides whether the newly highlighted Placemarker name is acceptable. If the name is acceptable, the user continues through the transfer point labeled “A”. If the name is not acceptable, the user returns to decision block 38. Upon returning to decision block 38, the user may shift further down the name list by again depressing the down arrow key. If, in decision block 38, the user does not want to shift down, the alternative is to shift up the name list by pressing the up arrow key on the keyboard, as shown in functional block 48. In response to the up arrow keystroke, the algorithm moves the highlight up the name list to the next listed Placemarker name in functional block 50. The algorithm then advances to functional block 44 where the JAWS® speech synthesizer reads the newly highlighted Placemarker name. The algorithm then advances to decision block 46 where the user decides whether the newly highlighted Placemarker name is acceptable. As before, if the name is acceptable, the user continues through the transfer point labeled “A”. If the name is not acceptable, the user again returns to decision block 38. Upon returning to decision block 38, the user may shift further up the name list by again depressing the up arrow key. While three decision blocks 36, 38 and 46 are shown in FIG. 4, it will be appreciated that the decision blocks are illustrative of an interactive association between the user and the algorithm, as described above. Thus, in the preferred embodiment, the decisions are made by the user pressing either the up arrow or down arrow keys on his keyboard or one of the command buttons on the dialog box. The invention also contemplates an alternate method for selecting a Placemarker name in which the user may simply presses the key corresponding to the first letter of the desired Placemarker name in place of deciding whether to shift up or down the displayed list of names in decision block 38 (not shown). Pressing the key corresponding to the first causes the algorithm to move to that name on the list. Thus, pressing the “T” key will transfer the user to the Temporary Placemarker, if one is included in the name list. The newly selected name is then recited as before. If the recited name is acceptable, the user continues through the transfer point labeled “A”. If the recited name is not acceptable, the user may either depress another key or return to decision block 38. Upon passing through the transfer point A, the algorithm continues with the flow chart shown in FIG. 6. As indicated above, there are six labeled command buttons shown to the right of the display screen in FIG. 5 while two option buttons are shown at the bottom of the screen. Corresponding to upper five command buttons, there are five decision blocks included to the left of FIG. 6. These decision blocks, which are described in the following, correspond to the user selecting and pressing the corresponding command button. Thus, while the decision blocks are shown and described insequence in the flow chart of FIG. 6, the invention contemplates that the user may proceed directly to any one of the command buttons. The command buttons are sequentially selected by depressing the tab key on the keyboard. After the tab key is depressed, the JAWS® speech synthesizer reads the control key label to inform the user of the currently selected command button selection. Pressing the enter key on the keyboard depresses the selected command button. Alternately, a key associated with the underlined letter in the label for each of the display command buttons may be utilized to select and press the button. For example, pressing the A key while holding down the ALT key will select and press the “Add” command button. When the Placemarker List dialog box is first opened, the “Move To” command button is currently selected if a Placemarker name is selected, as illustrated by decision block 60. The invention contemplates that the “Move To” command button is only available if one or more Placemarkers are listed on the screen. If there are no designated Placemarkers, the “Move To” button will be grayed out and thereby not available. If the user wants to move to the location corresponding to the selected Placemarker, he depresses the enter key on his keyboard to depress the “Move To” button on the display screen, as indicated by functional block 62. The algorithm then advances to functional block 64 and moves to the location in the document corresponding to the selected Placemarker name. The JAWS® speech synthesizer would then recite the line of the document for the selected location to provide audio feedback to the user. The algorithm advances to exit block 66 where the dialog box is closed and the algorithm terminates. The next command option to be discussed is the “Add” option that appears at the top of the set of command buttons included in the Placemarker List dialog box shown in FIG. 5. The “Add” button will insert a fixed Placemarker into a JAWS® file that corresponds to at the current location of the Virtual cursor and also add a name corresponding to the new Placemarker to the list shown on the dialog box display screen. The “Add” option is accessed in decision block 68 by selecting the Add button and depressing the ENTER key on the key board. This action causes the algorithm to open an “Add Placemarker” dialog box, as shown in functional block 70 and illustrated in FIG. 7. The Add Placemarker dialog box has one edit field that is used to specify the name of the new Placemarker. If the user has marked a blank field in the document, the edit field also will be blank Otherwise a portion of the document text at the location of the Virtual cursor will be displayed in the edit field as a default Placemarker name. The Add Placemarker dialog box also includes two command buttons labeled “OK” and “CANCEL”. When the dialog box is opened, the OK button is selected as a default setting. The algorithm advances to functional block 72 in which the JAWS® speech synthesizer recites the current contents of the of the edit field. The algorithm then advances to decision block 74 where the user decides whether or not to use the default name displayed in the edit field. The user can reject the default name by typing a name into the edit field in functional block 76. The user then depresses the ENTER key on the keyboard in functional block 78 to press the OK button in the dialog box. Upon depressing the ENTER key, the algorithm inserts a fixed Placemarker into the document and adds the name in the edit line to the list of Placemarker names. The algorithm then advances to functional block 80 and moves to the location in the document corresponding to the new Placemarker name. The JAWS® speech synthesizer would then recite the line of the document for the selected location to provide audio feedback to the user, as shown in functional block 82. The algorithm advances to exit block 66 where the “Add Placemarker” dialog box is closed and the algorithm terminates. i, in decision block 74, the user is satisfied with the default name appearing in the edit line in the Add Placemarker dialog box, he depresses the ENTER key to transfer the algorithm directly to functional block 78 to add the marker to the document at the current location of the Virtual cursor and the default name to the name list. As with the temporary Placemarkers, by utilizing the Virtual PC Cursor, the user can insert fixed Placemarkers into documents that do not have a keyboard accessible cursor, such as a flashing vertical line. As described above, the “Add Placemarker” dialog box also includes a CANCEL command button. The CANCEL button may be selecting with the tab key at any time that the “Add Placemarker” dialog box is open. After selecting the CANCEL button, depressing the ENTER key will close the dialog box and exit the algorithm. The present invention also includes a shortcut to access the “Add” option directly from the HTML document. The shortcut is illustrated in the upper right corner of FIG. 6 and consists of the entry box labeled 84. Entry box 84 indicates that depressing the K key twice within one second while holding down the CTRL key will open the “Add Placemarker” dialog box directly from the document. The “Add Placemarker” dialog box may then be used as described above to add a fixed Placemarker to the document without having to first open the Placemarker dialog box shown in FIG. 5. The next control option to be discussed is the “Change Name” option that appears third from the top of the set of command buttons included in the Placemarker List dialog box shown in FIG. 5. Selecting the “Change Name” button and depressing the ENTER key in decision block 84 opens a “Change Placemarker Name” dialog box over the Placemarker List dialog box, as shown in functional block 86 and illustrated in FIG. 8. The Change Placemarker Name dialog box has one edit field that displays the currently selected Placemarker name. Similar to the Add Placemarker dialog box, the Change Placemarker Name dialog box also includes two command buttons labeled “OK” and “CANCEL”. When the dialog box is opened, the OK button is selected as a default setting. The algorithm then advances to functional block 88 where the user types in a new name. Pressing the ENTER key in functional block 90 changes the name of the fixed Placemarker, closes the Change Placemarker Name dialog box and returns the algorithm to the PlaceMaker List dialog box through transfer point A. As described above, the Change Placemarker Name dialog box also includes a CANCEL command button. The CANCEL button may be selected with the tab key at any time that the “Change Name” dialog box is open. After selecting the CANCEL button, depressing the ENTER key will return the algorithm to the PlaceMaker dialog box through transfer point A. The present invention contemplates that the “Change Name” dialog box may be used to convert a Temporary Placemarker to a fixed Placemarker by changing the name of the Temporary Placemarker. The next command option to be discussed is the “Remove” option that appears fourth from the top of the set of command buttons included in the Placemarker List dialog box shown in FIG. 5 and is used to remove the currently selected Placemarker from the document. Selecting the “Remove” button and depressing the ENTER key in decision block 92 transfers the algorithm to functional block 94 where the currently selected Placemarker is removed from the document and the associated name is deleted from the list displayed in the Placemarker dialog box. The algorithm then exits through box 66. If there are no Placemarkers in the document, the “Remove” command button will be grayed out and not available for use. The final command option to be discussed is the “Remove All” option that appears fifth from the top of the set of command buttons included in the Placemarker List dialog box shown in FIG. 5 and is used to remove all of the Placemarkers, both fixed and temporary, from the document. Selecting the “Remove All” button and depressing the ENTER key in decision block 96 transfers the algorithm to decision block 98 where a dialog box (not shown) appears to confirm the command by presenting a message that reads: “Are you sure you want to remove all Place Markers?” The JAWS® speech synthesizer recites the message for the user. The user uses the tab key to select either a YES button or a NO button included in the dialog box and then presses the ENTER key. Pressing the NO button returns the user to the Placemarker dialog box via the transfer point A. Pressing the YES button advances the algorithm to functional block 100 where all of the Placemarkers are removed from the document and all of the corresponding Placemarker names are deleted from the list of names displayed in the Placemarker List dialog box. The algorithm then exits through box 66. If there are no Placemarkers in the document, the “Remove All” command button will be grayed out and not available for use. As shown in FIG. 5, the Placemarker List dialog box also includes a CANCEL command button in the functional block labeled 102. While the block 102 is shown below the decision blocks discussed above, the CANCEL button may be selecting with the tab key at any time that the Placemarker List dialog box is open. After selecting the CANCEL button, depressing the ENTER key will close the dialog box and terminate the algorithm through exit box 66. The Placemarker List dialog box also includes a pair of option buttons at the bottom of the box. The option buttons specify whether the Placemarkers should be sorted and display in “Tab Order” or in “Alphabetical” order. When Tab Order button is selected, the Placemarkers are displayed in element order that is based upon the order in which elements were rendered to the Virtual cursor buffer. When the Alphabetical button is selected, the Placemarkers are displayed in alphabetical order. In the preferred embodiment, the Tab Order button is selected by default when the dialog box is opened; however, either button may be selected with the TAB key and then activated by pressing the ENTER key on the keyboard. The present invention also includes a quick navigation feature that allows the user to select a previously defined Placemarker without opening the Placemarker dialog screen. The quick navigation feature is illustrated by the flow chart shown in FIG. 9 and is entered through block 110 by depressing the K key on the keyboard. The algorithm is responsive to the K key to shift forward in the document to the next Placemarker following the previously accessed Placemarker, as shown in functional block 112. The previously accessed Placemarker may be either the most recently added Placemarker or the previous Placemarker used, whichever occurred later. The JAWS® speech synthesizer then recites the newly selected Placemarker in functional block 114 and the subroutine moves to the place in the document corresponding to the newly selected Placemarker in functional block 116. The algorithm advances to decision block 118 and waits for another keystroke. If another K keystroke is entered, as shown in functional block 120, the algorithm again shifts forward in the document to the next Placemarker, as shown in functional block 122. The algorithm then returns to functional block 114, recites the name of the newly selected Placemarker and continues as described above. If a different keystroke is entered in decision block 118, the algorithm then exits through block 124 and proceeds to implement the action that corresponds to the entered keystroke. Also, the invention contemplates that cycling through the Placemarkers will wrap upon reaching the last Placemarker in the document. Thus, upon reaching the last Placemarker in the document, an additional K keystroke will cause the algorithm to move to the beginning of the document and search for the first Placemarker contained in the document. The present invention includes another quick navigation feature that is illustrated by the flow chart shown in FIG. 10 and that is entered through block 130 by depressing the SHIFT+K keys on the keyboard. The algorithm is responsive to the SHIFT+K keys to shift backward in the document to the previously accessed Placemarker, as shown in functional block 132. The previously accessed Placemarker may be either the most recently added Placemarker or the previous Placemarker used, whichever occurred later. The JAWS®) speech synthesizer then recites the selected Placemarker in functional block 134 and the subroutine moves to the place in the document corresponding to the selected Placemarker in functional block 136. The algorithm then advances to decision block 138 and waits for another keystroke. If another set of SHIFT+K keystrokes are entered, as shown in functional block 140, the algorithm shifts further back in the document to the next Placemarker ahead of the current Placemarker, as shown in functional block 142. The algorithm then returns to functional block 134, recites the name of the newly selected Placemarker and continues as described above. If a different keystroke is entered in decision block 138, the algorithm then exits through block 144 and proceeds to implement the action that corresponds to the entered keystroke. Also, the invention contemplates that cycling through the Placemarkers will wrap upon reaching the top of the list first Placemarker in the document. Thus, upon reaching the first Placemarker in the document, additional SHIFT+K keystrokes will cause the algorithm to move to the end of the document and search for the last Placemarker contained in the document. In FIG. 11, user 180 moves PC cursor 190 over the screen display 11 using mouse 170. Keyboard commands are accepted by user 180 through keyboard 160. JAWS® screen reader program interprets underlying code of web display and outputs speech to speakers 150. FIG. 12 illustrates a sample stock quote webpage that provides stock XYZ price 200 and stock ZYX price 210. User 180 moves cursor 190 to insert Placemarkers for each stock price. FIG. 13 shows the underlying HTML code for the stock quote webpage. Stock XYZ price 200 is located at Tag15 and stock price ZYX is located at Tag19. PMI file 220 shows an INI file structure wherein id=15 for XYZ stock price 200 and id=19 for ZYX stock price. As the stock price values immediately start from the 15th or 19th tag, no offset value is needed. As there is no frame set, the FrameIndex value is a null (i.e., −1). The invention contemplates that the fixed Placemarkers are retained within their own proprietary Placemarker file that is written and read by the JAWS® screen reader program. In the preferred embodiment, the Placemarker file is utilizes PMI extensions. Because the Placemarkers are stored in a separate file, the fixed Placemarkers are preserved when the user moves between pages or windows of the displayed document. However, the temporary Placemarkers are erased whenever the user moves between pages or windows of the displayed document. Additionally, the fixed Placemarkers may be used at a later date when a document is revisited, even if the document text has been changed, provided that there has not been too much structural change in the document. This feature is intended to facilitate returning to specific locations within favorite web sites. For example, if the user frequents a web site maintained by a retailer, the details of the web site may change with inventory changes, but the general layout of the web site will probably be the same. Thus, the user may mark portions of the web site of particular interest, such as, for example, audio equipment. Upon returning to the web site, the user would need only to activate the Placemarker for audio equipment. The algorithm would then move to the corresponding location on the web site and display audio equipment upon the computer monitor. The invention also contemplates that the JAWS® speech synthesizer will recite the number of Placemarkers present on a page when the user returns to a previously viewed page. Additionally, because the Placemarkers are maintained within a separate JAWS® file that is totally independent of the document, users may exchange fixed Placemarkers with other users of JAWS®. Thus, neither the web page carrying the document nor the document itself is aware of the existence of the Placemarker file associated with the particular document, which is entirely different from prior art bookmark features. Site and Title information concerning the document also are stored in the Placemarker file and are utilized by JAWS® to determine which Placemarker file should be accessed for a particular document. The inventors expect that this feature will be most helpful on HTML based applications being used by multiple JAWS® users at a common location. With the present invention, the user independently loads the document through his application and uses JAWS® to both interact with and acquire data from the application and the document. While the preferred embodiment has been illustrated and described in terms of the JAWS® screen reader, it will be appreciated that the invention also may be practiced with other types of screen readers. Additionally, it will be appreciated that the flow charts illustrated in the figures are exemplary and that the invention also can be practiced with flowcharts other than those specifically shown. Furthermore, the invention contemplates that a Braille display can be used in conjunction with, or in place of, an audio screen reader. In the former case, where the flow charts indicate recitation, the information would be displayed upon a Braille display while it is recited. In the later case, the information would only be displayed upon a Braille display with out any audio. In either case, the Braille display could either be available for a predetermined time period and then cleared or the Braille display could remain until replaced by the next usage. To summarize, Placemarkers allow a user to quickly and easily navigate to commonly used areas of his favorite web pages or HTML documents. The user can utilize Placemarkers to jump between certain areas of a page, mark important sections of an HTML document, or indicate key form elements. For example, the user could use Placemarkers to move to required fields in a complicated form or specific paragraphs in a long HTML document. The user presses Press K to move to the next Placemarker, or presses SHIFT+K to move to the prior Placemarker. Pressing CTRL+K places a temporary Placemarker. The invention also allows transfer to a numeric location of a Placemarker. To read or move to a specific Placemarker, the user presses CTRL+shift plus the numbers 1-N to read, and the same keystroke twice to move to the Placemarker. For example, to read the text at the location of the fifth Placemarker, the user presses CTRL+SHIFT+5. To move to the fifth Placemarker, press CTRL+SHIFT+5 twice quickly. Pressing CTRL+SHIFT+K to displays a list of all Placemarkers on the current page. Use the UP/DOWN ARROW keys to select a Placemarker in the list. Then press SPACEBAR on the Move To button or press ALT+M to move the virtual cursor to the Placemarker's location on the page. To add a Placemarker: Open a web page or other HTML document. Move the cursor to the location on the page where you want to put the Placemarker. Press CTRL+SHIFT+K. Press SPACEBAR on the Add button or press ALT+A. JAWS suggests a name for the Placemarker based on the text present at the cursor's current location. The user may enter a new name if necessary. Press SPACEBAR on the OK button to add the Placemarker to this page. To change the name of a Placemarker: The user opens the page containing the Placemarker that he wants to rename. The user presses CTRL+SHIFT+K to display a list of Placemarkers on this page. The user uses the UP/DOWN arrow keys to select the Placemarker. He then presses the SPACEBAR on the Change Name button or presses ALT+C. He enters a new name for the Placemarker and then press SPACEBAR on the OK button. Placemarkers added in this way remain there until the user removes them. The user can add a temporary Placemarker by pressing CTRL+K. Temporary Placemarkers only remain for the current session, and only one temporary Placemarker exists at a time. To remove one or more Placemarkers: The user open the page containing the Placemarker you want to delete. He then presses CTRL+SHIFT+K to display a list of all Placemarkers on the current page. He uses the UP/DOWN ARROW keys to select a Placemarker. The user then presses SPACEBAR on the Remove button or press ALT+R to delete the Placemarker. If the user wants to delete all Placemarkers for this page, he presses SPACEBAR on the Remove All button or press ALT+L. To share the Placemarkers with other JAWS users: The user presses WINDOWS KEY+E to start Windows Explorer. He then goes to the drive and folder where you installed JAWS. He opens the SETTINGS\ENU\Placemarkers folder. Placemarker information is stored in .PMI files. Locate the .PMI file with the same name as the page containing the Placemarkers user wants to share. The user copies this file and distribute it to other users. These users then need to copy the .PMI file into the JAWS5O\SETTTNGS\ENTJ\Placemarkers folder on their computers. The users can now navigate that HTML page with your Placemarkers. To automatically play the Placemarkers responsive to navigation to a URL: The user presses INSERT SHIFT V which opens the Personalize Settings Dialog (FIG. 14). The user presses C to move to the Custom Page Summary Speak Custom Summary choice and taps the space bar one time. The user toggles to read: Virtualize Custom Summary and presses Enter to accept. After navigating to a URL with preexisting Placemarkers, the Virtual Viewer display appears on top and it will contain the Placemarker information. The user can stop the automatic reading and arrow around in the text with both speech and Braille. The names you created for the PlaceMarkers are shown here as links. If you move to one and press enter, the Virtual Viewer goes away, and you land back on the Fast Quotes Page on the Line of the place Marker. Forms Mode is turned off at that point and you can arrow around. Use F to go back to the Symbols Edit Field and press enter for Forms Mode to find another Symbol. Note that if you just press Escape from the Virtual Viewer, you will land back on the Fast Quotes Page and still be in Forms Mode as expected. It will be seen that the advantages set forth above, and those made apparent from the foregoing description, are efficiently attained and since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matters contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween. Now that the invention has been described,

<SOH> BACKGROUND OF INVENTION <EOH>During the infancy of the World Wide Web (herein “the Web”), documents transferred via hypertext protocol (“HTTP”) were frequently static and unchanging over long periods of time. However, as the web evolved, website were more frequently updated and linked to live databases. These new websites became dynamic, changing their displayed output as the linked database was updated. In most cases, database driven web sites maintained a consistent appearance. The tables, colors, fonts and other layout and formatting options were the same. However, the information placed within the layouts would change. Modern development tools such as Microsoft's ASP.NET provides tools to rapidly construct web pages dynamically linked to backend databases. For the average web users, viewing dynamic data is a convenience. Users check changing stock prices, sports scores, headlines, weather conditions and the like. In addition, many valuable databases are placed online so that anonymous users have limited access to their resources. The end user must type in a query in a web form which is then assembled into a query string. A SQL string is constructed from the information on the web form and the results are displayed. Sophisticated users and programmers sometimes write applications that “mine” a publicly accessible database to collect the contents of the database for their own use. Although some may question the ethics or legality of such database mining, it is important to note the underlying technology is known as “screen scraping.” In other words, the software application uses complex string handling routines to locate dynamically changing data on a website and store the results. Screen scraping has existed well before the advent of the web. Many terminal modes such as 3270, used to connect to mainframes, were “scraped” of data at predetermined locations on the display screen. To develop such a screen scraping application for the web a programmer will typically examine the HTML source code of the web page near the data element sought to be mined. The programmer will find a string of alphanumeric characters that consistently appears next to the target data element and use that string as a reference point. For example, if an HTML tag calls for a table cell to be a certain background color, the programmer may have the application look for that tag, go three lines down, twenty characters across and copy the next ten characters to a database field. A drawback of this method is that the author of the web page may change the page layout whereby the reference point is no longer valid. For users with full vision, finding dynamically changing data is typically not a problem. Web sites designers attempt to display the information in a format easy to assimilate. However, visually impaired (also known as “low-vision”) users often have difficultly finding a particular portion of a web page. While screen readers assist the visually impaired user by reading the output of a web page, a low-vision user may only want to hear about certain dynamically changing data on a web page. For example, a screen reader on a financial website may take a couple minutes to read the content between the top of the page and the current value of the Dow Jones Industrial Average (the “Dow”). A low-vision user may want to periodically check the Dow to see if the applicable stocks are going up or down for the day. It would be cumbersome to force the user to listen to other content on the page when all he or she wants to know about is the current value of the Dow. Although this information could be “scraped” by examining the HTML source code, writing a custom application for each individual website would also be cumbersome for the low-vision user. As a user moves though an HTML document downloaded from the Internet with a screen reader, he may want to return to a previously read portion of the document. Unfortunately, currently available screen readers do not provide the capability to return to a specified place within the document, such as a word or line. Instead, the user must return to the beginning of the document and search for the desired location. Therefore, it would be desirable to provide a capability to mark the text of a HTML document with a tag and to be able return to the tagged portion of the text in the future upon demand. What is needed is a method to locate where dynamically changing information appears on a web page whereby a screen reader can quickly provide the information to the low-vision user. Another need in the art is for a method of finding the location of this information without requiring the end user to engaging in complex string handing routines.

<SOH> SUMMARY OF INVENTION <EOH>The present invention includes a screen reader that provides access to both software applications and the Internet. The screen reader includes a speech synthesizer that operates with a sound card in a personal computer to read aloud information appearing upon the computer screen. The screen reader provides access to a wide variety of software applications. The reader includes an interface that provides output to refreshable Braille displays. The screen reader has two cursors available to assist the user when using an application in the operating system, the PC cursor and the screen reader cursor The PC cursor is linked to the keyboard functions of the software applications and is used when typing information, moving through options in dialog boxes and making a selection of a particular option. Thus, as each key is pressed, the speech synthesizer recites the letter corresponding to the key or the name of the selected option. The screen reader cursor is linked to mouse pointer functions in the software applications to provide access to information in an application window that is beyond the scope of the PC cursor. For example, as the user maneuvers the mouse pointer over a tool bar, the speech synthesizer recites the name of the particular toolbar button that the pointer is over. In addition, the screen reader supports web browsers with special features such as link lists, frame lists, forms mode and reading of HTML labels and graphic labels included on web pages. Upon entering an HTML document via a URL, the screen reader actuates a virtual cursor that mimics the functions of the PC cursor. The virtual cursor causes the speech synthesizer to speak the number of frames in a document displayed upon the monitor screen and the number of links in the frame currently being displayed. In addition, the speech synthesizer reads graphics labeled by alternate tags in the HTML code. An embodiment of the present invention includes a method of marking the position of a dynamically changing string in a document including the steps of retrieving the document, establishing a cursor location in the document associated with the beginning of the dynamically changing string, parsing the source HTML in the document for a positional value representative of the number of HTML tags prior to the cursor location, identifying the URL of the document, and storing the value and the URL on a computer accessible medium. Additional steps include retrieving the positional value and URL from the computer accessible medium, requesting the document associated with the URL, parsing the source HTML in the document until the quantity of tags parsed equals the positional value, and outputting the dynamically changing string at the cursor location. The step of outputting the dynamically changing string at the cursor location may be executed by an output means selected from the group consisting of a speech synthesizer, a Braille reader, a screen magnification application, and a pop-up display window. Outputting the dynamically changing string may be performed responsive to navigation to the associated URL. A position for an entire domain may also be stored whereby common headers that propagate across an entire domain are bypassed so that the cursor is positioned at content that is distinct between web pages in the domain.

20040806

20060131

20050210

92978.0

HUTTON JR, WILLIAM D

DOCUMENT PLACEMARKER

SMALL

ACCEPTED

ACCEPTED

METHOD FOR CONTROLLING A HYBRID VEHICLE

A method for controlling a wheel drive system of a hybrid electric vehicle when starting a power source. The hybrid electric vehicle includes first and second power sources, a motor, and a power transfer unit adapted to drive a vehicle wheel. The method includes determining whether the first power source is to be started, determining whether a level of torque requested by a vehicle operator is greater than a threshold value, maintaining a current gear ratio if the threshold value is exceeded, and providing a target level of torque to the power transfer unit.

1. A method for controlling a wheel drive system of a hybrid electric vehicle when starting a power source, the hybrid electric vehicle having first and second power sources, a motor configured to be driven by the first and/or second power sources, and a power transfer unit having a plurality of gear ratios, the power transfer unit configured to be driven by the motor to drive a vehicle wheel, the method comprising: determining whether the first power source is to be started; determining whether a level of torque requested by a vehicle operator is greater than a threshold value if the first power source is to be started and the hybrid electric vehicle is in motion; maintaining a current gear ratio if the level of torque requested by the vehicle operator is greater than the threshold value; and providing a target level of torque with the motor while the current gear ratio is engaged. 2. The method of claim 2 wherein the step of determining whether the level of torque requested by the vehicle operator is greater than the threshold value further comprises determining whether the level of torque requested by the vehicle operator is less than an upper limit value. 3. The method of claim 1 wherein the current gear ratio is maintained for a predetermined period of time. 4. The method of claim 1 wherein the first power source is an internal combustion engine selectively coupled to the motor via a clutch. 5. The method of claim 1 wherein the second power source is a battery. 6. The method of claim 1 wherein the level of torque requested by the vehicle operator is based on a signal from an accelerator pedal position sensor. 7. The method of claim 1 wherein the threshold value is based on the current gear ratio of the power transfer unit. 8. The method of claim 1 wherein the step of determining the target level of torque based on the current gear ratio and the level of torque demanded by the vehicle operator. 9. A method for controlling a wheel drive system of a hybrid electric vehicle during a rolling start, the hybrid electric vehicle having first and second power sources, a motor adapted to be powered by at least one of the power sources, and a power transfer unit having a plurality of gear ratios, the power transfer unit being adapted to be driven by the motor to drive a vehicle wheel, the method comprising: determining whether to start the first power source; determining whether a level of torque requested by a vehicle operator is greater than a threshold value indicative of a level at which a power transfer unit gear ratio downshift would be desired; inhibiting a downshift to a lower gear ratio for a predetermined period of time; and providing an additional amount of torque to the vehicle wheel with the motor and second power source while the downshift to the lower gear ratio is inhibited. 10. The method of claim 9 wherein the step of providing an additional amount of torque includes determining an amount of torque that would be available if the target gear ratio were engaged. 11. The method of claim 10 wherein the additional amount of torque is equal to the amount of torque that would be available if the target gear ratio were selected. 12. The method of claim 9 wherein the motor is a starter-alternator. 13. The method of claim 9 wherein the predetermined period of time is less than or equal to 3 seconds. 14. The method of claim 9 wherein the level of torque requested by the vehicle operator is based on a signal from an accelerator pedal position sensor. 15. A method for controlling a wheel drive system of a hybrid electric vehicle during an engine start, the hybrid electric vehicle comprising an engine, a voltage source, a power transfer unit adapted to drive a vehicle wheel and having a plurality of gear ratios, a motor-generator selectively coupled to the engine via a first clutch, selectively coupled to the power transfer unit via a second clutch, and adapted to be powered by at least one power sources, the method comprising: determining whether an engine start-up is requested while the hybrid electric vehicle is moving; determining whether a level of torque requested by a vehicle operator exceeds a threshold value associated with a current gear ratio; starting a timer; inhibiting a gear ratio shift of the power transfer unit; starting the engine; calculating an amount of torque to provide to the power transfer unit while in the current gear ratio; providing the amount of torque to the power transfer unit with the motor-generator while the engine is being started; and repeating the inhibiting, calculating, and providing steps until a predetermined period of time measured by the timer has elapsed. 16. The method of claim 15 wherein the step of determining whether the level of torque requested by the vehicle operator exceeds the threshold value further comprises permitting a shift from the current gear ratio to a target gear ratio if the level of torque requested exceeds a limit value indicative of a wide open throttle condition. 17. The method of claim 15 wherein the step of calculating the amount of torque to provide to the power transfer unit is based on the current gear ratio, a target gear ratio that would be engaged if a gear ratio shift were permitted, and the level of torque requested by the vehicle operator. 18. The method of claim 15 wherein the level of torque requested by a vehicle operator is based on a signal from an accelerator pedal position sensor. 19. The method of claim 15 further comprising engaging the first clutch while the engine is being started. 20. The method of claim 15 further comprising engaging the second clutch after the engine has started.

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. provisional application Ser. No. 60/501,766 filed Sep. 10, 2003. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to the control of a hybrid electric vehicle, and more particularly to a method for controlling a wheel drive system of a hybrid electric vehicle. 2. Background Art Previously, hybrid electric vehicles employed control strategies that restricted “shift-up” actions of an automatic transmission to reduce shifting shocks that occurred as power source output decreased. An example of such a control strategy is described in U.S. Pat. No. 5,982,045. However, these hybrid vehicle control strategies did not address the problems associated with executing a transmission downshift to a lower gear ratio while simultaneously starting a drive power source, such as an engine of the hybrid electric vehicle. SUMMARY OF THE INVENTION According to one aspect of the present invention, a method for controlling a wheel drive system of a hybrid electric vehicle when starting a power source is provided. The hybrid electric vehicle includes first and second power sources, a motor, and a power transfer unit. The motor is configured to be driven by the first and/or second power sources. The power transfer unit has a plurality of gear ratios and is adapted to be driven by the motor to drive a vehicle wheel. The method includes determining whether the first power source is to be started, determining whether a level of torque requested by a vehicle operator is greater than a threshold value, maintaining a current gear ratio if the level of torque requested by the vehicle operator is greater than the threshold value, and providing a target level of torque with the motor while the current gear ratio is engaged. The method inhibits gear backlashes that may occur when a transmission downshift is executed when a power source is being started. Moreover, the method inhibits the undesirable noises and component life degradation that results from a gear backlash. The level of torque requested by the vehicle operator may be based on a signal from an accelerator pedal position sensor. The step of determining whether the level of torque requested by the vehicle operator is greater than the threshold value may also include determining whether the level of torque requested by the vehicle operator is less than an upper limit value. The threshold value may be based on the current gear ratio of the power transfer unit. The first power source may be an internal combustion engine. The second power source may be a battery. The motor may be a starter-alternator. According to another aspect of the present invention, a method for controlling a wheel drive system of a hybrid electric vehicle during a rolling start is provided. The hybrid electric vehicle includes first and second power sources, a motor, and a power transfer unit. The motor is configured to be driven by at least one power source. The power transfer unit has a plurality of gear ratios and is adapted to be driven by the motor to drive a vehicle wheel. The method includes the steps of determining whether to start the first power source, determining whether a level of torque requested by a vehicle operator is greater than a threshold value indicative of a level at which a power transfer unit gear ratio downshift would be desired, inhibiting a downshift to a lower gear ratio for a predetermined period of time, and providing an additional amount of torque to the vehicle wheel with the motor and second power source while the downshift to the lower gear ratio is inhibited. The method inhibits gear backlashing and improves vehicle driveability by inhibiting backlash events and associated noises and changes in wheel torque during the predetermined period of time in which a gear backlash may be likely to occur. The step of providing the additional amount of torque may include determining an amount of torque that would be available if a target gear ratio were engaged. The additional amount of torque may be the difference between an amount of torque provided in the current gear ratio and the amount of torque that would be provided if the target gear ratio was selected. According to another aspect of the present invention, a method for controlling a wheel drive system of a hybrid electric vehicle during an engine start is provided. The hybrid electric vehicle includes an engine, a voltage source, a power transfer unit, and a motor-generator. The power transfer unit is adapted to drive a vehicle wheel and has a plurality of gear ratios. The motor-generator is selectively coupled to the engine via a first clutch, selectively coupled to the power transfer unit via a second clutch, and is adapted to be powered by at least one power source. The method includes determining whether engine start-up is requested, determining whether a level of torque requested by a vehicle operator exceeds a threshold value associated with a current gear ratio, starting a timer, inhibiting a gear ratio shift of the power transfer unit, starting the engine, calculating an amount of torque to provide to the power transfer unit while in the current gear ratio, providing the amount of torque to the power transfer unit with the motor-generator while the engine is being started, and repeating the inhibiting, calculating, and providing steps until a predetermined period of time measured by the timer has elapsed. The step of determining whether the level of torque requested by the vehicle operator exceeds the threshold value may include permitting a shift from the current gear ratio to a target gear ratio if the level of torque requested exceeds a limit value indicative of a wide open throttle condition. The amount of torque to provide to the power transfer unit may be based on the current gear ratio, a target gear ratio that would be engaged if a gear ratio shift were permitted, and the level of torque requested by the vehicle operator. The first clutch may be engaged while the engine is being started. The second clutch may be engaged after the engine has started. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a schematic of a hybrid electric vehicle. FIG. 2 is a flowchart of a method for controlling a wheel drive system of the hybrid electric vehicle. FIG. 3 is a plot depicting the operation of the hybrid electric vehicle in accordance with the method of FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) Referring to FIG. 1, a schematic of a hybrid electric vehicle 10 is shown. The hybrid electric vehicle 10 includes a first wheel set 12, a second wheel set 14, and a drivetrain 16. The wheel drive system or drivetrain 16 may be configured to drive or provide torque to the first and/or second wheel sets 12,14. The drivetrain 16 may have any suitable configuration, such as a parallel drive, series drive, or split hybrid drive as is known by those skilled in the art. In the embodiment shown in FIG. 1, a parallel drive configuration is shown. The hybrid electric vehicle 10 may also include a plurality of power sources. In the embodiment shown in FIG. 1, the hybrid electric vehicle 10 includes a primary power source 18 and a secondary power source 20. However and suitable number of power sources may be employed. The primary power source 18 may be any suitable energy generation device, such as an internal combustion engine or a fuel cell. The secondary power source 20 may be any suitable voltage source, such as a battery, capacitor, or fuel cell. If a battery is used it may be of any suitable type, such as nickel-metal hydride (Ni—MH), nickel-iron (Ni—Fe), nickel-cadmium (Ni—Cd), lead acid, zinc bromine (Zn—Br), or lithium based. If a capacitor is used it may be of any suitable type, such as an ultra capacitor, super capacitor, electrochemical capacitor, or electronic double layer capacitor as is known by those skilled in the art. The primary and secondary power sources 18,20 are adapted to provide power to the drivetrain 16. The primary power source 18 is selectively coupled to an electrical machine, such as a motor, motor-generator, or starter-alternator 22 via a first clutch 24. If the first clutch 24 is engaged, the primary power source 18 may propel the hybrid electric vehicle 10. If the first clutch 24 is disengaged, the secondary power source 20 may power the starter-alternator 22 to propel the hybrid electric vehicle 10. In addition, both the primary and secondary power sources 18,20 may simultaneously provide power to the starter-alternator 22. An inverter 26 may be disposed between the secondary power source 20 and the starter-alternator 22. The inverter 26 converts direct current (DC) to alternating current (AC) when current flows from the secondary power source 20 and converts alternating current (AC) to direct current (DC) when current flows to the secondary power source 20. The starter-alternator 22 may be selectively coupled to a power transfer unit 28 via a second clutch 30. The power transfer unit 28 may be of any suitable type, such as a multi-gear step ratio transmission or an electronic converterless transmission as is known by those skilled in the art. The power transfer unit 28 is adapted to drive one or more vehicle wheels. More specifically, the power transfer unit 28 is connected to a differential 32 by a driveshaft. The differential 32 is connected to each wheel of the second wheel set 14 by a pair of halfshafts or axles 34. Optionally, the hybrid electric vehicle 10 may be configured with one or more energy recovery devices, such as a regenerative braking system that captures kinetic energy when the brakes are applied and returns the recovered energy to the secondary power source 20 via the starter-alternator 22. A vehicle system control module 36 may monitor and control various aspects of the hybrid electric vehicle 10. For example, the control module 36 may be connected to the primary power source 18 and power transfer unit 28 to monitor and control their operation and performance. In addition, the control module 36 may receive input signals from various components. These components may include a motor speed sensor 38 and an accelerator pedal position sensor 40. The motor speed sensor 38 detects the rotational velocity of the starter-alternator 22. The accelerator pedal position sensor 40 detects the driver's commands for acceleration of the hybrid electric vehicle 10. In a hybrid electric vehicle such as that previously described, it is undesirable to simultaneously start the primary power source or engine and execute a power transfer unit gear ratio shift while the vehicle is in motion, also known as a “rolling start”, for three main reasons. First, if the gear ratio is changed while the engine is being started, the gears of the differential and/or power transfer unit may backlash. More specifically, a gear backlash condition may occur when the gear torque switches between a positive torque (in which the vehicle wheels are driven by the drivetrain) and a negative torque (in which the compression braking effect of the engine provides a retarding torque). Gear backlash may be perceived by vehicle occupants as an undesirable bump or clunk and may reduce component life. Second, the configuration of the hybrid vehicle drivetrain may create physical limitations that prohibit a gear ratio shifts while starting the engine. For example, vehicle control logic may attempt to engage and disengage a particular clutch at the same time. Third, a secondary power source or the starter-alternator may run out of capacity to provide the desired level of torque to the power transfer unit when a gear ratio shift and engine start coincide. As a result, a vehicle occupant may perceive a lack of acceleration or vehicle responsiveness. Consequently, it may be desirable to provide additional torque with the starter-alternator to adequately respond to a driver's acceleration commands. Referring to FIG. 2, a flowchart of a method for controlling the wheel drive system of the hybrid electric vehicle 10 is shown. The method may inhibit power transfer unit gear ratio shifts when the primary power source is being started and may provide additional torque to the power transfer unit and vehicle wheels. As will be appreciated by one of ordinary skill in the art, the flowchart represents control logic which may be implemented using hardware, software, or combination of hardware and software. For example, the various functions may be performed using a programmed microprocessor. The control logic may be implemented using any of a number of known programming or processing techniques or strategies and is not limited to the order or sequence illustrated. For instance, interrupt or event-driven processing is employed in real-time control applications, rather than a purely sequential strategy as illustrated. Likewise, pair processing, multitasking, or multi-threaded systems and methods may be used to accomplish the objectives, features, and advantages of the present invention. This invention is independent of the particular programming language, operating system processor, or circuitry used to develop and/or implement the control logic illustrated. Likewise, depending upon the particular programming language and processing strategy, various functions may be performed in the sequence illustrated at substantially the same time or in a different sequence while accomplishing the features and advantages of the present invention. The illustrated functions may be modified or in some cases omitted without departing from the spirit or scope of the present invention. In this flowchart, the term “engine start” denotes activation of the primary power source. However, the present invention contemplates that the primary power source may not be an engine as previously discussed. At 100, the method begins by determining whether engine start-up is desired. This determination may be based on an engine start-up signal provided to or by the control unit. An engine start-up signal may occur in many situations, such as when the secondary power source has a low charge or when more power is demanded by the driver than the secondary power source can provide. If engine start-up is not requested, the process continues at block 116 where the strategy is discontinued. If engine start-up is requested, the process continues a block 102. At 102, the method determines whether the torque requested by the driver is greater than a threshold value. The torque requested by the driver may be based on a signal from the accelerator pedal position sensor. This signal may be converted into a torque value in a manner known by those skilled in the art. The threshold value may be based on the current gear ratio of the power transfer unit. More specifically, a threshold value may be associated with each gear ratio. These threshold values may be stored in a lookup table for access by the control unit. The threshold values may be established by vehicle calibration testing and the associated shift schedules of the power transfer unit. If the torque requested by the driver is not greater than a threshold value, the process ends at block 116. If the torque requested by the driver is greater than a threshold value, the process continues a block 104. At 104, an optional step is shown. In this optional step, the method determines whether the torque requested by the driver is less than an upper limit value. More particularly, if a very high level of vehicle acceleration or torque is requested by the driver, such as a wide open throttle condition, the method does not need to be implemented since the very high torque demand makes it unlikely that gear backlash could occur until after the engine is started. The upper limit value may be based on vehicle calibration testing and the design attributes of the power transfer unit. If the torque requested by the driver is less than an upper limit value, the process continues a block 106. At 106, a timer is started. The timer is used to determine how long to maintain the current gear ratio of the power transfer unit and may exceed the amount of time needed to start the engine. At 108, gear ratio shifts of the power transfer unit are inhibited (i.e., the current gear ratio is maintained). At 110, the method determines an additional amount of torque that would be provided if the power transfer unit were permitted to the downshift to a target gear ratio. The target gear ratio is the gear ratio that would be engaged if a gear ratio shift were permitted. The additional amount of torque may be determined as a function of the following expression: (GRTarget−GRCurrent)*TorqueDemand where: GRTarget is the target gear ratio, GRCurrent is the current gear ratio of the power transfer unit, and TorqueDemand is the level of torque demanded by the vehicle operator. At 112, the method provides the additional amount of torque to the power transfer unit to improve acceleration responsiveness. The additional torque may be provided using the starter-alternator and the second power source. At 114, the method determines whether a predetermined amount of time has elapsed. More specifically, the elapsed time measured by the timer is compared to a predetermined time value. The predetermined time value is indicative of the amount of time needed to start the engine and may be determined by vehicle testing. For example, the predetermined value is less than or equal to three seconds. If the predetermined amount of time has not elapsed, the method returns to block 108. If the predetermined amount of time has elapsed, the method ends at block 116 where gear ratio shifts are enabled. Referring to FIG. 3, a plot depicting the operation of the hybrid electric vehicle in accordance with the method of FIG. 2 is shown. The plot depicts the change of various vehicle parameters over time. More particularly, from top to bottom, the plot depicts the accelerator pedal position, current gear ratio of the power transfer unit, the desired or target gear ratio, and the axle or halfshaft torque. The vertical axes differ for each vehicle parameter depicted in the plot. The accelerator pedal position is shown as a percentage. 100% designates a fully actuated accelerator pedal or wide open throttle condition. 0% designates a fully released accelerator pedal (i.e., the accelerator pedal is not pressed). The current and desired gear ratios are expressed as integers (e.g., “4” designates fourth gear, “3” designates third gear, etc.). Referring to the halfshaft torque plot, two lines are shown. The solid line represents the halfshaft torque without the control method of the present invention. The dotted line represents the halfshaft torque when the method of the present invention is employed. In the absence of the control method of the present invention, the halfshaft torque (solid line) shifts from negative to positive at approximately 1.75 seconds and between positive and negative values between 5 and 6 seconds. This shifting is indicative of gear backlash in the drivetrain, such as in the differential or power transfer unit. More particularly, when the present invention is not employed, an fast engine start is requested to quickly respond to the driver's request for acceleration. The fast engine start results in a negative to positive torque shift at approximately 1.75 seconds. In addition, the driver's acceleration request would normally result in a downshift from third gear to second gear between approximately 2.75 and 3.0 seconds. Such a gear ratio shift results in shifts between positive and negative torque values between 5 and 6 seconds. In contrast, the halfshaft torque measured when the control method of the present invention is employed (dotted line) does not shift between positive and negative values. As such, gear backlash is inhibited. The operation of the method in accordance with the present invention will now be described in more detail. At time 0 (t=0) the engine is turned off and the hybrid electric vehicle is in motion, such as may occur when the vehicle is coasting or being powered by a secondary power source. The halfshaft torque is a negative value (indicative of regenerative braking). At approximately 0.75 seconds, the driver presses the accelerator pedal approximately 60% as shown in the accelerator pedal position plot. The control unit interprets the change in the accelerator pedal position as a request for a high level of acceleration or wheel torque. In response, the control unit requests that the engine be started. The control unit also compares the requested level of torque to the threshold value. In this scenario, the threshold level is exceeded, resulting in the execution of blocks 106 through 114 of the method in FIG. 2. Consequently, the timer is started and gear ratio shifts are inhibited for a predetermined period of time. In this scenario, the predetermined period of time is 3.0 seconds. At approximately 1.1 seconds, the control unit determines a downshift to a lower gear ratio (from third gear to second gear) is desirable to provide the requested level of torque. However, the gear ratio shift is not implemented and the power transfer unit remains in third gear as indicated by the current gear plot. At approximately 3.6 seconds, the control unit determines that an upshift to a higher gear ratio (from second to third gear) would be desirable. However, such a gear shift is not implemented since the power transfer unit is already in third gear. At approximately 3.75 seconds, the predetermined period of time has elapsed and the strategy is discontinued. While the best mode for carrying out the invention has been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.

<SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The present invention relates generally to the control of a hybrid electric vehicle, and more particularly to a method for controlling a wheel drive system of a hybrid electric vehicle. 2. Background Art Previously, hybrid electric vehicles employed control strategies that restricted “shift-up” actions of an automatic transmission to reduce shifting shocks that occurred as power source output decreased. An example of such a control strategy is described in U.S. Pat. No. 5,982,045. However, these hybrid vehicle control strategies did not address the problems associated with executing a transmission downshift to a lower gear ratio while simultaneously starting a drive power source, such as an engine of the hybrid electric vehicle.

<SOH> SUMMARY OF THE INVENTION <EOH>According to one aspect of the present invention, a method for controlling a wheel drive system of a hybrid electric vehicle when starting a power source is provided. The hybrid electric vehicle includes first and second power sources, a motor, and a power transfer unit. The motor is configured to be driven by the first and/or second power sources. The power transfer unit has a plurality of gear ratios and is adapted to be driven by the motor to drive a vehicle wheel. The method includes determining whether the first power source is to be started, determining whether a level of torque requested by a vehicle operator is greater than a threshold value, maintaining a current gear ratio if the level of torque requested by the vehicle operator is greater than the threshold value, and providing a target level of torque with the motor while the current gear ratio is engaged. The method inhibits gear backlashes that may occur when a transmission downshift is executed when a power source is being started. Moreover, the method inhibits the undesirable noises and component life degradation that results from a gear backlash. The level of torque requested by the vehicle operator may be based on a signal from an accelerator pedal position sensor. The step of determining whether the level of torque requested by the vehicle operator is greater than the threshold value may also include determining whether the level of torque requested by the vehicle operator is less than an upper limit value. The threshold value may be based on the current gear ratio of the power transfer unit. The first power source may be an internal combustion engine. The second power source may be a battery. The motor may be a starter-alternator. According to another aspect of the present invention, a method for controlling a wheel drive system of a hybrid electric vehicle during a rolling start is provided. The hybrid electric vehicle includes first and second power sources, a motor, and a power transfer unit. The motor is configured to be driven by at least one power source. The power transfer unit has a plurality of gear ratios and is adapted to be driven by the motor to drive a vehicle wheel. The method includes the steps of determining whether to start the first power source, determining whether a level of torque requested by a vehicle operator is greater than a threshold value indicative of a level at which a power transfer unit gear ratio downshift would be desired, inhibiting a downshift to a lower gear ratio for a predetermined period of time, and providing an additional amount of torque to the vehicle wheel with the motor and second power source while the downshift to the lower gear ratio is inhibited. The method inhibits gear backlashing and improves vehicle driveability by inhibiting backlash events and associated noises and changes in wheel torque during the predetermined period of time in which a gear backlash may be likely to occur. The step of providing the additional amount of torque may include determining an amount of torque that would be available if a target gear ratio were engaged. The additional amount of torque may be the difference between an amount of torque provided in the current gear ratio and the amount of torque that would be provided if the target gear ratio was selected. According to another aspect of the present invention, a method for controlling a wheel drive system of a hybrid electric vehicle during an engine start is provided. The hybrid electric vehicle includes an engine, a voltage source, a power transfer unit, and a motor-generator. The power transfer unit is adapted to drive a vehicle wheel and has a plurality of gear ratios. The motor-generator is selectively coupled to the engine via a first clutch, selectively coupled to the power transfer unit via a second clutch, and is adapted to be powered by at least one power source. The method includes determining whether engine start-up is requested, determining whether a level of torque requested by a vehicle operator exceeds a threshold value associated with a current gear ratio, starting a timer, inhibiting a gear ratio shift of the power transfer unit, starting the engine, calculating an amount of torque to provide to the power transfer unit while in the current gear ratio, providing the amount of torque to the power transfer unit with the motor-generator while the engine is being started, and repeating the inhibiting, calculating, and providing steps until a predetermined period of time measured by the timer has elapsed. The step of determining whether the level of torque requested by the vehicle operator exceeds the threshold value may include permitting a shift from the current gear ratio to a target gear ratio if the level of torque requested exceeds a limit value indicative of a wide open throttle condition. The amount of torque to provide to the power transfer unit may be based on the current gear ratio, a target gear ratio that would be engaged if a gear ratio shift were permitted, and the level of torque requested by the vehicle operator. The first clutch may be engaged while the engine is being started. The second clutch may be engaged after the engine has started.

20040902

20061003

20050310

73905.0

PANG, ROGER L

METHOD FOR CONTROLLING A HYBRID VEHICLE

UNDISCOUNTED

ACCEPTED

ACCEPTED

METHOD TO DETECT TERMITE INFESTATION IN A STRUCTURE

A method for confirming the presence of termites in a structure, involving a preliminary infrared scan of a structure and confirmation of termite infestation with at least one detector in order to quickly locate potential areas of termite infestation.

1. A method to nondestructively confirm termite infestation sites in a structure comprising: (a) performing a preliminary infrared scan of said structure to identify potential infestation sites; (b) positioning at least one detector at said potential infestation sites to confirm termite infestation; and (c) nondestructively confirming termite infestation sites in a structure. 2. The method of claim 1 wherein said at least one detector is a microwave motion detector. 3. The method of claim 1 wherein at least one detector is a dog. 4. The method of claim 1 wherein in said at least one detector is a gas detector. 5. The method of claim 1 wherein said at least one detector is an x-ray detector. 6. The method of claim 1 further including the step of heating said structure. 7. The method of claim 1 further including the step of cooling said structure. 8. The method of claim 1 wherein said at least one detector is a fiber optic scope.

CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part and claims the benefit under 35 U.S.C. §120 of U.S. application Ser. No. 10/680,377 filed Oct. 7, 2003 and U.S. application Ser. No. 10/708,571 filed Mar. 11, 2004, and 35 U.S.C. § 119(e) of U.S. Provisional Application Ser. No. 60/417,257 filed Oct. 9, 2002, hereby specifically incorporated by reference in their entirety. BACKGROUND OF THE INVENTION This invention relates to nondestructive detection of termite infestation in a structure and, more particularly, to methods for detecting and preventing termite damage. SUMMARY OF THE INVENTION Termites are extremely destructive to wood material. Termites attack and destroy wood almost everywhere in the world, with the exception of climate zones that experience hard freezing. There are close to fifty species of termites in the United States, the majority of losses to wood material being caused by subterranean species. All termites are social insects. They live in colonies that can number over one million individuals. It is difficult to put a dollar amount estimate on termite damage. However, renowned termite scientist Dr. Nan Yao Su at the University of Florida has estimated that the total annual cost of termite control and damage repair for the United States alone was $11 billion in 1999. Few homes are treated for termite detection/prevention during construction, although this is the best and most economical way to prevent termite attack. Untreated foundations make the house very susceptible to termite attack. It is often very difficult and costly to apply effective control measures after a building has become infested with termites. It is rarely apparent from visual observation that a termite infestation is active and that wood damage is occurring. Typically, only about 30 percent of structural wood in a structure is visible for visual inspection. Even when visible wood is to be inspected, an inspector often has to rely on secondary signs of an infestation, such as moisture staining, the presence of foraging tubes and debris expelled from termite colonies. Another method often used to detect termites is to tap the surface of the wood while listening for a characteristic sound indicative of an underlying gallery void. When a suspected area is located, the inspector applies a sharp probe, such as a screwdriver, to break the wood surface and locate wood galleries and live termites. This method has significant disadvantages. The confirmation of an active infestation requires some localized damage to the wood. Also, when termites are exposed in this manner, the destruction induces termites to retreat from the disturbed area and may reduce the effectiveness of a subsequent localized treatment. Commercial demand for a dependable, nondestructive and nonsubjective method to detect termites has spawned a number of alternatives to visual inspection. However, none of these techniques has satisfied the non-destructive and non-subjective requirements, and many infestations are still missed. Prior devices for nondestructive detection of termites may be generally classified into four categories: (1) Apparatus having sensors that detect the presence of gases emitted by termites, as disclosed for example in U.S. Pat. No. 6,150,944; (2) Apparatus having acoustic sensors that detect insect sounds at high or ultrasonic frequencies, as disclosed for example in U.S. Pat. No. 4,809,554 to Shade et al., U.S. Pat. No. 5,285,688 to Robbins et al., and Japanese Patent Application JP H07-143837; (3) Apparatus having sensors that detect destruction of a baited sample, for example, inclusion of circuit elements designed to be destroyed as the sample is destroyed, thereby breaking a circuit, as disclosed in U.S. Pat. Nos. 6,052,066; 5,815,090; 5,592,774; activation of a switch by movement of a mechanical element in response to sample destruction, as disclosed in U.S. Pat. No. 5,571,967 and Japanese Patent Publication No. H7-255344; or penetration of a film across the entrance to a baited trap, as disclosed in U.S. Pat. No. 5,877,422; and (4) Apparatus employing infrared sensors. Detection devices that rely on sensing the presence of termite-created gases eliminate the need to use bait to attract the termites, and, in theory, they can signal the actual locations of the termites. A significant disadvantage, however, is that the gases must be abstracted within a confined space, such as within the walls of a structure. These devices are thus unsuitable for detecting termites in wood that is not within a confined space. Moreover, the use of these devices to detect termites is very time-consuming and costly as a result. Detection devises that rely on sensing ultrasonic termite sounds, on the other hand, offer the advantage that they can be placed on the exterior of structural walls rather than within the walls. The ultrasonic frequencies, however, are difficult to detect through walls and other concealing structures due to the signal's very short distance of travel (ultrasonic frequencies have very high transmission loss), and this process fails to take into account the full range of termites noises, which fall primarily in the range of 100 Hz to 15 kHz. An alternative to devices employing ultrasonic acoustic sensors is a device employing sensor (or electronic stethoscope) arranged to detect acoustic signals and process them for listening and directs interpretation by a trained operator. In some cases, the device may be connected to a spectrum analyzer arranged to generate a plot of signals in the frequency domain, which can then be interpreted by the operator. These devices require a high degree of operator skill. In addition, such devices typically use a relatively narrow frequency range. For example, the device disclosed in U.S. Pat. No. 4,895,025 is focused on a frequency range of 1462.5 Hz to 3337.5 Hz. The device of U.S. Pat. No. 4,941,356 (the '356 patent), on the other hand, is evidently intended to work over a broad range of audible frequencies (100 Hz to 15 kHz). The '356 patent, however, fails to disclose specific apparatus, algorithms or noise patterns useful for detection over the specified frequency range. The various devices for sensing the destruction of bait sample are useful for detecting the presence of termites in the vicinity of a structure, but cannot be used to locate precise areas of termite infestation in concealed areas within the structure. Once it has been determined that termites are present in the vicinity of the structure, the only way to determine the actual locations of termites within the structure is to remove portions of the structure, which is, again, damaging and costly. It has also been proposed to use infrared sensors to detect the surface temperature differences indicative of termite infestations. Infrared detection works because subterranean termites require a high percentage of humidity in their living environment. Moisture brought in by the termites produce a temperature change in the wall, which can be detected by an infrared thermal imaging device. However, this is a relatively nonspecific method, yielding many, many false positives since there are many sources of temperature differences in a typical structure, such as non-uniform insulation material, air-conditioning ducts, leakage, air movement through wall cracks, water and moisture problems, etc. As a result, detection of termites using infrared sensors still requires destruction of walls to verify results and to more specifically locate the actual termite infestations. Furthermore, use of infrared sensing for detection of termites also requires a relatively high degree of operator skill, training and judgment which adds time and cost to its use. Devices relying on acoustic detection appear to offer the best combination of accuracy and lack of destruction. Such devices, however, generally do not take into account the full range of termite sounds, as explained above. Moreover, the design of prior devices has generally resulted in only highly localized detection ability, thereby necessitating the taking of many samples or data points, and requiring an inordinate amount of time or number of sensors to completely inspect a structure. As a result of the various practical difficulties outlined above, the prior devices described above have generally seen insignificant commercial implementation despite the long-felt need for nondestructive termite and wood-destroying insect detection. There is still a need for a nondestructive, reliable and easy-to-use apparatus and method for detecting termites. The present invention relates to a method to detect termite infestation. In particular, an infrared scan of a structure is conducted to identify potential infestation sites. Then once potential infestation sites are identified, another nondestructive detection method such as a microwave is used to confirm termite infestation in the structure. Preliminary infrared detection has the advantage of covering a much larger area than acoustic detection and, although less specific or accurate than acoustic detection, provides efficient screening and a convenient way of scanning the structure for potential infestations in order to guide placement of detectors in order to carry out more specific tests. In this way, inspection time requirements, and, therefore, costs, are greatly reduced. Further, detection accuracy is greatly increased. The combination of infrared and other detection method couples a quicker but low-specificity screening technique for speed with a high-specificity, slower technique for accuracy and is a significant improvement in the art having important commercial applications. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic illustration of a termite detection system assembled in accordance with the principles of a preferred embodiment of the invention. FIG. 2A is an infrared scan of a structure showing drywood termite infestation. FIG. 2B is a photo of a wood structure with the surface material removed. FIG. 3A is an infrared scan of a structure showing drywood termite infestation. FIG. 3B is a photo of a wood structure with the surface material removed. FIG. 4A is a photograph of a wall. FIG. 4B is an infrared scan of the wall. FIG. 4C is a photograph of the wall with the dry wall removed, it shows the2×4 stud damaged by subterrarean termite. DETAILED DESCRIPTION As schematically depicted in FIG. 1, a preferred embodiment of the apparatus and method of the present invention includes a thermal imaging camera 1 for performing a preliminary scan of a structure 13 in order to locate potential termite infestations sites 3. A thermal imaging camera 1 is used to perform an infrared scan. The structure 13 can be a wooden object, such as a wall stud, paneling or in one embodiment a live tree. Termite infestation sites 3 can be the result of subterranean termite or dry-wood termite activity. In the case of a subterranean termite infestation, the moisture brought in by the subterranean termites will show up as a “suspicious cold or hot spot” in a thermal imaging scan. In the case of a dry-wood termite infestation, a heat or cold source 9 is needed to increase or decrease the temperature of a targeted structure 13. This heat source 9 can be an electric, gas or oil heat source as well as an incandescent or infrared light source. The areas in the targeted structure 13 that contain a cavity created by dry-wood termites will show up as “suspicious warm or hot spots.” The correspondent video images of the potential termite infestation are recorded by the camcorder 2 or by the thermal imaging camera if it is equipped with recording capability 6. Thermal imaging camera 1 may be any of a number known, commercially available infrared cameras conventionally used by structural engineers, police and the military. In order to improve the accuracy by which the thermal imaging camera 1 detects potential areas of termite infestation, the thermal imaging camera may further include termite infestation recognition software, such as matched filtering software which compares the frequency spectrum of a thermal image with frequency spectra of a reference images known to indicate termite infestation, thereby reducing the level of skill required of the camera operator, reducing time required and increasing termite identification effectiveness. This database of infestation images of suspicious thermal images can be built by one skilled in the art. Specific equipment to facilitate an infrared scan of a structure and procedures to enhance the resolution of the scan are described in U.S. patent application Ser. No 10/708,571. Referring now to FIGS. 2A and 2B, an infrared scan of a wall shows potential termite damage at 50, 51 and 52. The surface material was removed in FIG. 2B to show termite damage at 53, 54 and 55. Referring now to FIGS. 3A and 3B, an infrared scan of a wall shows potential drywood termite damage at 61-67. The surface material was removed in FIG. 2B to show termite damage at 70-76. FIG. 4A 4C show additional preliminary infrared detection. In FIG. 4A, a photograph of a wall is shown. This is what a human eye sees. In FIG. 4B, a preliminary infrared scan shows suspicious black spots which might be subterranean termite infestation. Subterranean termite infested areas contain very high moisture content, as the moisture evaporates infested areas appear as cold spots. In FIG. 4B, when the wall is removed, actual termite damage is shown at 60 and 61. However, it would be better to confirm wood damaging termite damage or infestation prior to destructive of the dry wall. More specifically, upon a preliminary thermal indication of termite infestation observed with thermal imaging camera 1, detectors are positioned on the wall of the structure adjacent to the potentially infested locations in the structure 13. The detectors can be used to confirm termite infestation. These detectors include but are not limited to microwave motion detector, dogs, sound (acoustic), fiber optic scope, and gas detection and x-ray detection. A microwave motion detector can detect termite movement inside the wall cavity, however, the operator must be perfectly still while holding the device. Very often high moisture content in the wall cavity prevents an accurate measurement. Moisture content; however, can be differentiated through infrared detection. U.S. Forest Service, Mississippi. Additionally, dogs are now being used by some pest control specialists in the detection of termites. The handler/inspector is a key part of this inspection team. This individual should be a well-trained termite inspector, and also someone who can properly handle and care for the dog and become familiar with the cues and responses the dog gives when it detects an insect infestation. Truman's Scientific Guide to Pest Control Operations, 5th Edition. Gas detectors have been marketed to aid in termite inspections. Id. X-ray detection is one of the latest pinpoint inspection techniques. X-ray detection produces a good image of termite infestation in wood structure. However, this technique requires a radioactive source and can only be employed under very strict conditions in order to contain radio active radiation. This is an active device and requires FDA and EPA approval. In addition, the equipment is quite expensive and requires extensive training. Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it will be obvious that certain changes and modifications can be made which are within the full scope of the invention.

<SOH> BACKGROUND OF THE INVENTION <EOH>This invention relates to nondestructive detection of termite infestation in a structure and, more particularly, to methods for detecting and preventing termite damage.

<SOH> SUMMARY OF THE INVENTION <EOH>Termites are extremely destructive to wood material. Termites attack and destroy wood almost everywhere in the world, with the exception of climate zones that experience hard freezing. There are close to fifty species of termites in the United States, the majority of losses to wood material being caused by subterranean species. All termites are social insects. They live in colonies that can number over one million individuals. It is difficult to put a dollar amount estimate on termite damage. However, renowned termite scientist Dr. Nan Yao Su at the University of Florida has estimated that the total annual cost of termite control and damage repair for the United States alone was $11 billion in 1999. Few homes are treated for termite detection/prevention during construction, although this is the best and most economical way to prevent termite attack. Untreated foundations make the house very susceptible to termite attack. It is often very difficult and costly to apply effective control measures after a building has become infested with termites. It is rarely apparent from visual observation that a termite infestation is active and that wood damage is occurring. Typically, only about 30 percent of structural wood in a structure is visible for visual inspection. Even when visible wood is to be inspected, an inspector often has to rely on secondary signs of an infestation, such as moisture staining, the presence of foraging tubes and debris expelled from termite colonies. Another method often used to detect termites is to tap the surface of the wood while listening for a characteristic sound indicative of an underlying gallery void. When a suspected area is located, the inspector applies a sharp probe, such as a screwdriver, to break the wood surface and locate wood galleries and live termites. This method has significant disadvantages. The confirmation of an active infestation requires some localized damage to the wood. Also, when termites are exposed in this manner, the destruction induces termites to retreat from the disturbed area and may reduce the effectiveness of a subsequent localized treatment. Commercial demand for a dependable, nondestructive and nonsubjective method to detect termites has spawned a number of alternatives to visual inspection. However, none of these techniques has satisfied the non-destructive and non-subjective requirements, and many infestations are still missed. Prior devices for nondestructive detection of termites may be generally classified into four categories: (1) Apparatus having sensors that detect the presence of gases emitted by termites, as disclosed for example in U.S. Pat. No. 6,150,944; (2) Apparatus having acoustic sensors that detect insect sounds at high or ultrasonic frequencies, as disclosed for example in U.S. Pat. No. 4,809,554 to Shade et al., U.S. Pat. No. 5,285,688 to Robbins et al., and Japanese Patent Application JP H07-143837; (3) Apparatus having sensors that detect destruction of a baited sample, for example, inclusion of circuit elements designed to be destroyed as the sample is destroyed, thereby breaking a circuit, as disclosed in U.S. Pat. Nos. 6,052,066; 5,815,090; 5,592,774; activation of a switch by movement of a mechanical element in response to sample destruction, as disclosed in U.S. Pat. No. 5,571,967 and Japanese Patent Publication No. H7-255344; or penetration of a film across the entrance to a baited trap, as disclosed in U.S. Pat. No. 5,877,422; and (4) Apparatus employing infrared sensors. Detection devices that rely on sensing the presence of termite-created gases eliminate the need to use bait to attract the termites, and, in theory, they can signal the actual locations of the termites. A significant disadvantage, however, is that the gases must be abstracted within a confined space, such as within the walls of a structure. These devices are thus unsuitable for detecting termites in wood that is not within a confined space. Moreover, the use of these devices to detect termites is very time-consuming and costly as a result. Detection devises that rely on sensing ultrasonic termite sounds, on the other hand, offer the advantage that they can be placed on the exterior of structural walls rather than within the walls. The ultrasonic frequencies, however, are difficult to detect through walls and other concealing structures due to the signal's very short distance of travel (ultrasonic frequencies have very high transmission loss), and this process fails to take into account the full range of termites noises, which fall primarily in the range of 100 Hz to 15 kHz. An alternative to devices employing ultrasonic acoustic sensors is a device employing sensor (or electronic stethoscope) arranged to detect acoustic signals and process them for listening and directs interpretation by a trained operator. In some cases, the device may be connected to a spectrum analyzer arranged to generate a plot of signals in the frequency domain, which can then be interpreted by the operator. These devices require a high degree of operator skill. In addition, such devices typically use a relatively narrow frequency range. For example, the device disclosed in U.S. Pat. No. 4,895,025 is focused on a frequency range of 1462.5 Hz to 3337.5 Hz. The device of U.S. Pat. No. 4,941,356 (the '356 patent), on the other hand, is evidently intended to work over a broad range of audible frequencies (100 Hz to 15 kHz). The '356 patent, however, fails to disclose specific apparatus, algorithms or noise patterns useful for detection over the specified frequency range. The various devices for sensing the destruction of bait sample are useful for detecting the presence of termites in the vicinity of a structure, but cannot be used to locate precise areas of termite infestation in concealed areas within the structure. Once it has been determined that termites are present in the vicinity of the structure, the only way to determine the actual locations of termites within the structure is to remove portions of the structure, which is, again, damaging and costly. It has also been proposed to use infrared sensors to detect the surface temperature differences indicative of termite infestations. Infrared detection works because subterranean termites require a high percentage of humidity in their living environment. Moisture brought in by the termites produce a temperature change in the wall, which can be detected by an infrared thermal imaging device. However, this is a relatively nonspecific method, yielding many, many false positives since there are many sources of temperature differences in a typical structure, such as non-uniform insulation material, air-conditioning ducts, leakage, air movement through wall cracks, water and moisture problems, etc. As a result, detection of termites using infrared sensors still requires destruction of walls to verify results and to more specifically locate the actual termite infestations. Furthermore, use of infrared sensing for detection of termites also requires a relatively high degree of operator skill, training and judgment which adds time and cost to its use. Devices relying on acoustic detection appear to offer the best combination of accuracy and lack of destruction. Such devices, however, generally do not take into account the full range of termite sounds, as explained above. Moreover, the design of prior devices has generally resulted in only highly localized detection ability, thereby necessitating the taking of many samples or data points, and requiring an inordinate amount of time or number of sensors to completely inspect a structure. As a result of the various practical difficulties outlined above, the prior devices described above have generally seen insignificant commercial implementation despite the long-felt need for nondestructive termite and wood-destroying insect detection. There is still a need for a nondestructive, reliable and easy-to-use apparatus and method for detecting termites. The present invention relates to a method to detect termite infestation. In particular, an infrared scan of a structure is conducted to identify potential infestation sites. Then once potential infestation sites are identified, another nondestructive detection method such as a microwave is used to confirm termite infestation in the structure. Preliminary infrared detection has the advantage of covering a much larger area than acoustic detection and, although less specific or accurate than acoustic detection, provides efficient screening and a convenient way of scanning the structure for potential infestations in order to guide placement of detectors in order to carry out more specific tests. In this way, inspection time requirements, and, therefore, costs, are greatly reduced. Further, detection accuracy is greatly increased. The combination of infrared and other detection method couples a quicker but low-specificity screening technique for speed with a high-specificity, slower technique for accuracy and is a significant improvement in the art having important commercial applications.

20040903

20081014

20050127

69919.0

JAGAN, MIRELLYS

METHOD TO DETECT TERMITE INFESTATION IN A STRUCTURE

SMALL

CONT-ACCEPTED

ACCEPTED

PROGNOSTIC METHOD AND SYSTEM FOR HYBRID AND ELETRIC VEHICLE COMPONENTS

A prognostic method and system for testing and controlling various hybrid, fuel cell, and electric vehicle components. The tests generate test data for determining a state of the tested components. An operating strategy of the vehicle is controlled based on the state of its tested components.

1. A method for operating a vehicle, the method comprising: applying a test signal to a vehicle electric power component; generating a response from the component; determining an operating state of the component based at least in part on the response to the signal; and controlling vehicle operation based at least in part on the determined operating state of the component. 2. The method of claim 1, wherein controlling vehicle operation includes implementing a limited vehicle operating strategy based at least in part on detecting a degrading state for the component. 3. The method of claim 1, wherein controlling vehicle operation includes preventing further operation of the component. 4. The method of claim 1, wherein controlling vehicle operation includes indicating a degrading state of the component on a display. 5. The method of claim 1, wherein applying the test signal includes applying the signal to determine a forward-on voltage drop of the component. 6. The method of claim 1, wherein applying the test signal includes shutting off at least one other component and applying the signal to test for a leakage current in the component. 7. The method of claim 1, wherein applying the test signal includes applying the signal to determine a thermal impedance of the component. 8. The method of claim 1, wherein applying the test signal includes applying the signal to determine an AC impedance of the component. 9. The method of claim 1, wherein determining the response includes developing a response trend based on a number of responses, comparing the response trend to a predefined trend, and determining the state of the component based in part on the comparison. 10. The method of claim 9, wherein the state of the component indicates a need to limit degradation if the response trend differs from the predefined trend by a predefined margin. 11. The method of claim 1, wherein the vehicle includes an inverter for powering a motor and the component is the inverter, and wherein controlling vehicle operation includes limiting operation of the motor if the diagnosed state of the inverter indicates the inverter is degrading. 12. The method of claim 1, wherein the vehicle includes an inverter for powering a power steering unit and the component is the inverter, wherein controlling vehicle operating includes limiting operation of the power steering unit if the determined state of the inverter indicates the inverter is degrading. 13. The method of claim 1, wherein the vehicle includes an inverter for powering an air conditioning unit and the component is the inverter, and wherein controlling vehicle operation includes limiting operation of the air conditioning unit if the diagnosed state of the inverter indicates the inverter is degrading. 14. The method of claim 1, wherein the vehicle includes an auxiliary DC/DC converter and the component is the auxiliary DC/DC converter, wherein controlling vehicle operating includes limiting operation of the auxiliary DC/DC converter if the determined state of the auxiliary DC/DC converter indicates the auxiliary DC/DC converter is degrading. 15. The method of claim 1, wherein the vehicle includes an inverter for powering a fan/radiator unit and the component is the inverter, and wherein controlling vehicle operation includes limiting operation of the fan/radiator unit if the determined state of the inverter indicates the inverter is degrading. 16. The method of claim 1, wherein the vehicle includes a DC/DC converter that receives power from a fuel cell and a high voltage battery and that outputs power on a high voltage bus for powering the vehicle, wherein the component is the DC/DC converter, and wherein controlling vehicle operation includes limiting operation of the DC/DC converter if the determined state of the DC/DC converter indicates the DC/DC converter is degrading. 17. The method of claim 1, wherein the vehicle includes a fuel cell and an inverter for powering a fuel cell air compressor and the component is the inverter, wherein controlling vehicle operating includes limiting operation of the fuel cell if the determined state of the inverter indicates the inverter is degrading. 18. The method of claim 1, wherein the vehicle includes a fuel cell and an inverter for powering a fuel cell water pump and the component is the inverter, wherein controlling vehicle operation includes limiting operation of the fuel cell if the determined state of the inverter indicates the inverter is degrading. 19. A system for controlling operation of an electronic power component of a vehicle based at least in part on a determined state of the vehicle component, the system comprising: a prognostic module to diagnose the state of the vehicle component by providing a test signal thereto and determining a degrading state of the tested component based at least in part on a response of the tested component to the test signal if the determined state is degrading faster than a predefined degradation rate; and a vehicle system controller for controlling operation of the vehicle, the vehicle system controller being operable with the prognostic module to limit vehicle operation in response to detection of a degrading state of the tested component. 20. The system of claim 19 wherein the prognostic module test one of an inverter and a DC/DC converter.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prognostic system and method of testing and controlling vehicle components. It particularly relates to testing and determining an operating state of a vehicle component and controlling operation of the vehicle based on a prognosis of the operating state. 2. Background Art U.S. Pat. No. 6,484,080 relates to a method and system for controlling vehicle operation based on an operating state of one or more of its components. The operating state is determined by monitoring various vehicle components and inputting signals related thereto into a pattern recognition system. One problem with the method and system disclosed in the '080 patent is that its vehicle control elements cannot be prognostically tested. The method and system of the '080 patent is merely reactive. It records the operation characteristics of the components for comparison to predefined operational trends. Abnormal operation is determined, and corresponding vehicular control is undertaken, if the recorded operation differs from the predefined operational trends. The invention of the '080 patent fails to stress, probe, prompt, provoke or otherwise test the vehicle's components. Its reactive characteristic is unsuitable for testing the state of health of the components. It therefore is unsuitable for making a prognosis of an operation state of such tested components. Another limitation of the invention of the '080 patent is that it is not suitable for control of hybrid, fuel cell, and electric vehicles. Increased demand of these types of vehicles presents control needs relating to their wide dynamic ranges of operation and diverse usage profiles. These characteristics are not found in powertrains with traditional internal combustion vehicles, such as those of the '080 patent. A need exists in the art for a prognostic system and method for controlling hybrid vehicles, fuel cell vehicles and electric vehicles. The need extends to monitoring a state of the vehicle's components, and as power electronic modules, and to control operation of the vehicle based on a prognosis of the operating state of those components. SUMMARY OF THE INVENTION The present invention includes features for testing vehicle components and for controlling operation of the vehicle based on a prognosis of the state of health of the tested components, such as high efficiency, integrated, electronic power modules. In practicing the present invention a test signal is provided to a vehicle component. The test signal causes the vehicle component to develop a response to the test signal. A prognosis of an operating state of the tested component is based, at least in part, on its response to the test signal. Vehicle operation can then be modified in accordance with the operating state of the tested component. The modified vehicle operation can include implementing a limited operation strategy based, at least in part, on a degrading state for the tested component. The modified vehicle operation can include limiting operation or preventing further operation of a tested component or a component associated with the tested component. The modified vehicle operation can also include identifying a degrading state on an indicator. The indicator can be an alphanumeric display, a flashing light or the like. One aspect of the present invention relates to testing a vehicle component by using a test signal to determine a forward-on voltage drop of the tested component. Another aspect of the present invention relates to testing a vehicle component by disabling at least one non-tested component and using a test signal to determine a leakage current in the tested component. Another aspect of the present invention relates to testing a component by providing a test signal to determine thermal impedance of the component. Another aspect of the present invention relates to testing a component by using a test signal to test for an AC impedance of the tested component. Another aspect of the present invention relates to testing a component by using a test signal to determine a calculation state of the tested component. One advantage of the present invention is that response of the tested components to the test signals make it possible to predictively determine the state of the tested component. Another advantage of the present invention is that the states can be taken into account during execution of control strategies for controllers for powertrains in internal combustion engine powered vehicles, hybrid fuel cell vehicles and electric vehicles. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a hybrid vehicle having a prognostic module in accordance with the present invention; FIG. 2 illustrates a response trend for a tested component in accordance with the present invention; FIG. 3 illustrates a comparison of the response trend shown in FIG. 2 to a benchmark life expectancy trend in accordance with the present invention; and FIG. 4 illustrates a fuel cell vehicle having a prognostic module in accordance with the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) FIG. 1 illustrates an exemplary hybrid electric vehicle (HEV) 10 commonly referred to as parallel-series hybrid electric vehicle (PSHEV) 10. The present invention can be used, however, with any hybrid or non-hybrid system without deviating from the scope of the present invention, including vehicles powered by internal combustion engines, series hybrid electric vehicles (SHEV), parallel hybrid electric vehicles (PHEV), fuel cell vehicles (FIG. 4) and electric vehicles. HEV 10 includes electrically operated or controlled components including engine 14, transmission 16, and battery 20. These components operate with planetary gear set 24, generator 26, inverter 28, motor 30, and countershaft gearing 32 for powering differential axle 38 and wheels 40. DC/DC converter 44 regulates power provided to auxiliary loads 46. Power steering unit 50 provides power steering of dirigible wheels, not shown. Power steering unit 50 includes pump 54 powered by inverter motor 56. Fan/radiator unit 60, which cools motor 30 and engine 14, is powered by inverter 62. Air conditioning unit 66, which provides cooling for a vehicle passenger compartment includes compressor 68 powered by inverter motor 70. Transmission control module 72 controls and monitors the torque output of engine 14 and motor 30. Battery control module 76 monitors and controls battery 20. Vehicle system controller 78 (VSC) controls all aspect of vehicle operation. VSC 78 monitors vehicle operation and selects/controls HEV 10. VSC 78 generates and transmits signals to the vehicle components. The components operate as instructed by VSC 78. VSC 78 can control each component independently and collectively to control vehicle operation. HEV 10 includes prognostic module 86. Prognostic module 86 generates test signals for testing various vehicle components. The test signals generate test data in the tested components that prognostic module 86 uses to diagnose a state of health of the tested component. That information is fed back to VSC 78. VSC 78 can control operation of HEV 10 based on the state of health of the tested component. Multiple components can be tested and diagnosed simultaneously. Prognostic module 86 can be configured for operation with any vehicle component. The cost to configure prognostic module 86 is best offset if prognostic module 86 is configured for inverters and DC/DC converters, such as those described above. These electric components are both costly and important to vehicle reliability. It is desirable to accurately determine the states of such costly components so that vehicle operation can be controlled to limit their degradation. Usage degradation can be problematic if allowed to be continued without some preventive measure. Commonly, especially in hybrid and electric vehicles, the high voltages received by these electronic components can begin a slow degradation of the components. The degradation may begin slowly and then increase in rate if the degrading component is not monitored and the degradating effects limited. The present invention comprises a control strategy based on the monitored state of the tested component. The control strategy implements a limited operating strategy should one of the tested components begin to show degrading effects. The limited operating strategy permits HEV 10 to maintain varying levels of operation before shut-down. Shut-down is a last option as it can cause a substantial interruption to operation. Shut-down may be required to prevent permanent degradation to the tested component(s). A degrading component is discovered during its monitored state. The monitored states are determined from the test data gathered by prognostic module 86 during testing. The monitored states are used to indicate whether the tested component shows indications of degradation. The testing includes issuing test signals to the tested component and recording its response. The test signals are signals generated by prognostic module 86 and sent to the module being tested. The test signals are used to stress, probe, prompt, provoke, or otherwise test the component. The test signals sent to the tested component can be more beneficial in predicting degradation than merely recording a current operating state of the tested component. Acceptable operation under normal conditions can mask a greater underlying problem. The greater problem relates to the degradation of a component and its continued viability. Many vehicle components degrade over time and such degradation is expected. Degradation that causes a problem is that which exceeds a planned degradation schedule. It is too late to take preventive measure against unscheduled degradation if the testing system merely records the current operating state of the component. The present invention overcomes this by testing the components in a predictive manner. In one non-limiting aspect of the present invention, the test signals subject the tested component to operating conditions that the component would not typically experience. The test signal is transmitted/applied, for example, to test for a forward-on voltage of tested component. This is done by transmitting a preset current or voltage, or a combination of the two, to the tested component. The response of the tested component is determined by sensing its voltage drop. According to another aspect of the present invention the test signal is transmitted/applied to test for a leakage current in the tested component. This is done by applying a preset current or voltage, or a combination of the two, to the tested component. The response of the tested component is determined by sensing its leakage current. According to another aspect of the present invention the test signal is transmitted/applied to test for thermal impedance of the tested component. This is done by transmitting a preset current or voltage, or a combination of the two, with a power-pulse to the tested component. The response of the tested component is determined by measuring a change in temperature, such as a semi-conductor junction temperature or component case temperature or both. According to another aspect of the present invention the test signal is transmitted/applied to test for an AC impedance of the tested component. This is done by transmitting a preset current or voltage, or a combination of the two, to the tested component. The response of the tested component is determined by sensing the impedance of the tested component. The signals are known calibrating signals that produce predetermined responses of the tested component such that the degradation of the tested component can be determined. The testing of the tested component can be done on any schedule, preferably at least at vehicle start-up and, optionally, periodically during vehicle operation. Testing at start-up may limit interference with other systems in HEV 10 or permit shutting down of these other systems. Periodic testing during vehicle operation may permit testing for specific conditions that would not otherwise appear during start-up. The testing can correspond with different vehicle operating conditions to effect differential testing. The test signals can be generated and transmitted/applied to the tested module as necessary. The responses of the tested components are recorded. Recording includes data regarding the condition rules or vehicle state under which the test was conducted; i.e., whether the vehicle is in start-up or being driven. Prognostic module 86 can store data from a number of tests in a memory, along with the various parameters associated with the administration of the test signals, such as the driving conditions and the condition of other components in HEV 10. The responses to the test signal are stored by prognostic module 86 over time so that a history of responses can be kept and monitored. FIG. 2 illustrates an exemplary response trend line 108 for one tested component. Response trend line 108 indicates on the ordinate 112 the responses of the tested component to a number of tests of the tested component over time indicated on axis 110. Trend line 104 represents the severity of the degradation of the tested response on a relative scale. A worsening degradation is shown with increased vertical spacing of the plotted data relative to abscissa 110. Once a sufficient number of tests is recorded, analysis of the test responses can begin and a state of the tested component can be determined. This analysis can take a number of forms. In one case it can include an averaging and graphing of the tested responses. A slope of response trend 108 can be determined and used for subsequent comparison, and ultimately for obtaining a prognosis of the state of the tested component. FIG. 3 illustrates a comparison of response trend 108 to a benchmark life expectancy trend 120. The comparison is used to diagnose the state of the tested component. Response trend 108 includes first portion 124, second portion 128, and third portion 132. First portion 124 is relatively flat with a slight upward slope to illustrate a slight worsening in the response to the test signal. The difference in slope between first portion 124 of response trend 108 and a corresponding portion of life expectancy trend 120 can be used to predict whether the degradation severity is such that the tested component is operating in a degrading state. The degrading state triggers a modification to vehicle operation. The slight worsening of first portion 124, followed by more rapid worsening at second portion 128, can be interpreted as a warning sign that the tested component is beginning to degrade. If the degrading slope deviates more than a predetermined amount and life expectancy trend 120 does not increase at a corresponding rate, that will indicate that the tested components is beginning to degrade. The degrading of the tested component ideally matches the slope of life expectancy trend 120. An early warning can be provided to predict the degrading state of the tested component if the degrading slope deviates more than a predetermined amount. If the beginning of the upward movement of second portion 128 occurs at approximately the same time as in the life expectancy trend 120, a degrading state would not be determined. If the trend rapidly increases with a much greater slope than life expectancy trend 120, such as in portion 128 or 132, the degrading state may be determined. Although the difference in slope between response trend 108 and life expectancy trend 120 may not be sufficiently large to indicate a degrading state, such as open entry into portion 132, a rapidly increasing slope of response trend 108 can provide a sufficient basis for determining the degrading state. The slope of response trend 108 may suddenly change so drastically that it would be impossible for such a change to take place unless there were some sort of inaccuracy with prognostic module 86. In this case, the inaccuracy of the prognostic module is determined, rather than determining the degrading state of the tested module. Any number of parameters beyond differences in slope can be used to determine a degrading state. In addition, other parameters and computation means could be used without varying from the scope of the present invention. Fuzzy logic and/or neural networks may be used to integrate results from the different test signals, and to make adjustments to the life expectancy process based on learned behavior of the tested component, which may not have been known at the time of determining life expectancy trend. Fuzzy logic and neural networks may also be use to integrate a condition determination with a modification to vehicle operation in order to provide a better understanding of whether the desired compensation is working as intended. VSC 78 modifies vehicle operation if a degrading state is detected for the tested component. According to one non-limiting aspect of the present invention, the modified vehicle operation can include implementing a limited operating strategy for any number of vehicle controls. Preferably, the limiting operating strategy compensates for the degrading state of the tested component so that further degradation is limited as much as possible. One modification to vehicle operation can include activation of an indicator when the degrading state of the tested component is detected. Indicator 142 can be used for this purpose. Indicator 142 can be an indicator light, such as an LED, or an alphanumeric display. When the degrading state is determined, the indicator can be turned on or the alphanumeric display can display a message describing the degrading state and, optionally, the corrective action needed. Indicator 142 can also be controllable to communicate further degradation information in the event that the response trend continues to increase in slope, such as shown in third portion 132. Third portion 132 corresponds with severe degradation and a need to take immediate action. The severity can require vehicle shut-down. This can be communicated by flashing warning indicator 142 or changing to a flashing the alphanumeric display. In addition to or in place of indicator 142, prognostic module 86 can communicate a signal to VSC 78 to take corrective action based on the degrading state of the component experiencing the degradation. Preferably, the corrective action can be based on the severity of the degradation. The corrective action can be proportional to the difference in value or slope between response trend 108 and life expectancy trend 120. The degrading state may be determined with respect to inverter 28 in FIG. 1. VSC 78 can modify vehicle operation by controlling motor 30 to operate under limited power to limit further degradation of the inverter. If the diagnosed state is within second portion 128 (FIG. 3) of response trend 108 (FIG. 3), the degrading state may be compensated for by VSC 78 limiting power consumption of motor 30; i.e., by providing a limp-home function. If the degrading state of the inverter continues to increase, or is already determined to be operating within third portion 132, VSC 78 can prevent further operation of motor 30 and direct continued vehicle operation to be based solely on engine 14. This can be helpful to maintain continued vehicle operation until servicing can be obtained. The degrading state may be determined with respect to inverter 56 used in power steering unit 50. VSC 78 can modify vehicle by limiting operation of power steering unit 50 to limit further degradation to inverter 56. The limited operation of power steering unit 50 can be a decrease in power steering assist levels and/or shut-down of power steering in favor of manual steering. The degrading state may be determined with respect to inverter 70 used for powering an air conditioning unit 66. VSC 78 can limit operation of the air conditioning unit 66 to reduce further degradation to inverter 70. The limited operation of air conditioning unit 66 can be a decrease in cooling ability or shut-down of air conditioning unit 66. The degrading state may be determined with respect to auxiliary DC/DC converter 44. VSC 78 can modify vehicle operation by limiting operation of the auxiliary DC/DC converter 44 to limit its further degradation. The limited operation of auxiliary DC/DC converter 44 can be a decrease in power supplied to auxiliary loads 46 or shut-down of all power supplied to auxiliary loads 46 based on prioritized auxiliary load strategy. In some cases, some operation must be maintained, such as maintaining lighting systems. The degrading state may be determined with respect to inverter 62 used for powering fan/radiator unit 60. VSC 78 can modify vehicle operation by limiting operation of the fan/radiator unit 60 to limit further degradation to inverter 62. The limited operation of fan/radiator unit 60 can be a decrease in cooling operation or shut-down of all cooling. The shut-down of all cooling may further include shutting-down motor 30 or engine 14. FIG. 4 illustrates an exemplary fuel cell vehicle 150. The present invention includes modifying operation of the fuel cell vehicle 150 based on testing and monitoring a state of the fuel cell vehicle components. Fuel cell vehicles include components similar to those described above with respect to vehicles with internal combustion engines. Fuel cell vehicle 150 operates in a manner similar to that described above with respect to HEV 10. The common features and operation are shown with the same reference numerals as those used above with respect to HEV 10. The modified operation of fuel cell vehicle 150 in response to determining a degrading state for one or more of the components is likewise controlled. Unlike HEV 10, fuel cell vehicle 150 (FIG. 4) includes fuel cell 154 and a traction motor 156. Fuel cell 154 replaces engine 14, but it is similarly controlled by VSC 78. The traction motor 156, powered by inverter 158 and gearing 32, replaces planetary gear set 24 of FIG. 1 and is controlled by VSC 78. Inverter/Motor 156, 158 operates on power provide to high voltage bus 160. High voltage bus 160 receives power from DC/DC converter 162. DC/DC converter 162 receives power inputs from fuel cell 154 and high voltage battery 20. Fuel cell 154 further includes fuel cell air compressor 170 and water pump 172. Each includes respective inverter/motor combinations 176 and 178. Fuel cell air compressor 170 provides air to fuel cell 154. Fuel cell water pump 172 provides water to fuel cell 154. A degrading state may be determined with respect to DC/DC converter 162. VSC 78 can modify vehicle operation by limiting operation of DC/DC converter 162 to limit its further degradation. The limited operation of DC/DC converter 162 can be a decrease in power output and/or vehicle shut-down. A degrading state may be determined with respect to inverter 176, used for powering fuel cell air compressor 170. VSC 78 can modify vehicle operation by limiting operation of fuel cell 154 to limit further degradation to inverter 176. The limited operation of fuel cell 154 can be a decrease in power output or fuel cell 154 shut-down. The shut-down of fuel cell 154 provides a limp-home function as motor 156 can still be powered by power remaining in battery 20. A degrading state may be determined with respect to inverter 178, used for powering fuel cell water pump 172. VSC 78 can modify vehicle operation by limiting operation of fuel cell 154 to limit further degradation to inverter 178. The limited operation of fuel cell 154 can be a decrease in power output of fuel cell or fuel cell 154 shut-down. The shut-down of fuel cell 154 provides a limp-home function as motor can still be powered by power remaining in battery 20. A degrading state may be determined with respect to inverter 158 used for powering motor 156. VSC 78 can modify vehicle operation by limiting operation of motor 156 to limit further degradation to inverter 158. The limited operation of motor 156 can be a decrease in power output or shut-down. Continued monitoring of the modified vehicle operation can occur by prognostic module 86 and VSC 78. This can include any number of operations. Preferably it can include further modification to vehicle operations, such as the modifications described above with respect to a flashing warning light, or it can prevent further operation of motor, based on whether the modified vehicle operation is executing the necessary correction of the degraded condition. While the best mode for carrying out the invention has been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.

<SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The present invention relates to a prognostic system and method of testing and controlling vehicle components. It particularly relates to testing and determining an operating state of a vehicle component and controlling operation of the vehicle based on a prognosis of the operating state. 2. Background Art U.S. Pat. No. 6,484,080 relates to a method and system for controlling vehicle operation based on an operating state of one or more of its components. The operating state is determined by monitoring various vehicle components and inputting signals related thereto into a pattern recognition system. One problem with the method and system disclosed in the '080 patent is that its vehicle control elements cannot be prognostically tested. The method and system of the '080 patent is merely reactive. It records the operation characteristics of the components for comparison to predefined operational trends. Abnormal operation is determined, and corresponding vehicular control is undertaken, if the recorded operation differs from the predefined operational trends. The invention of the '080 patent fails to stress, probe, prompt, provoke or otherwise test the vehicle's components. Its reactive characteristic is unsuitable for testing the state of health of the components. It therefore is unsuitable for making a prognosis of an operation state of such tested components. Another limitation of the invention of the '080 patent is that it is not suitable for control of hybrid, fuel cell, and electric vehicles. Increased demand of these types of vehicles presents control needs relating to their wide dynamic ranges of operation and diverse usage profiles. These characteristics are not found in powertrains with traditional internal combustion vehicles, such as those of the '080 patent. A need exists in the art for a prognostic system and method for controlling hybrid vehicles, fuel cell vehicles and electric vehicles. The need extends to monitoring a state of the vehicle's components, and as power electronic modules, and to control operation of the vehicle based on a prognosis of the operating state of those components.

<SOH> SUMMARY OF THE INVENTION <EOH>The present invention includes features for testing vehicle components and for controlling operation of the vehicle based on a prognosis of the state of health of the tested components, such as high efficiency, integrated, electronic power modules. In practicing the present invention a test signal is provided to a vehicle component. The test signal causes the vehicle component to develop a response to the test signal. A prognosis of an operating state of the tested component is based, at least in part, on its response to the test signal. Vehicle operation can then be modified in accordance with the operating state of the tested component. The modified vehicle operation can include implementing a limited operation strategy based, at least in part, on a degrading state for the tested component. The modified vehicle operation can include limiting operation or preventing further operation of a tested component or a component associated with the tested component. The modified vehicle operation can also include identifying a degrading state on an indicator. The indicator can be an alphanumeric display, a flashing light or the like. One aspect of the present invention relates to testing a vehicle component by using a test signal to determine a forward-on voltage drop of the tested component. Another aspect of the present invention relates to testing a vehicle component by disabling at least one non-tested component and using a test signal to determine a leakage current in the tested component. Another aspect of the present invention relates to testing a component by providing a test signal to determine thermal impedance of the component. Another aspect of the present invention relates to testing a component by using a test signal to test for an AC impedance of the tested component. Another aspect of the present invention relates to testing a component by using a test signal to determine a calculation state of the tested component. One advantage of the present invention is that response of the tested components to the test signals make it possible to predictively determine the state of the tested component. Another advantage of the present invention is that the states can be taken into account during execution of control strategies for controllers for powertrains in internal combustion engine powered vehicles, hybrid fuel cell vehicles and electric vehicles.

20040910

20090707

20060316

87309.0

G06F1900

CAMBY, RICHARD M

PROGNOSTIC METHOD AND SYSTEM FOR HYBRID AND ELECTRIC VEHICLE COMPONENTS

UNDISCOUNTED

ACCEPTED

G06F

ACCEPTED

CELLULAR PHONE/PDA COMMUNICATION SYSTEM

A cellular PDA communication system for allowing a plurality of cellular phone users to monitor each others' location and status, to initiate cellular phone calls by touching a symbol on the display screen with a stylus or finger which can also include conferencing calling. The system also provides for remote activation of a cellular phone by an initiator causing the remote cellular phone to annunciate audio announcements, to call another phone number, to increase the volume of the speaker, to vibrate or to display images or videos. All this is accomplished with a conventional cellular phone PDA that includes GPS navigation with an enhanced improved software program.

1. A method of providing a cellular phone communication network for designated participating users, each having a similarly equipped cellular phone that includes a CPU, GPS navigational system and a touch screen display comprising the steps of: a) providing for the selective polling of position and status information from one user among all of the other users equipped with cellular phone/PDA/GPS system and its associated software; b1) providing for the entering of other entities of interest into the cellular phone CPU and assigning the other entities of interest a category; b2) providing the latitude and longitude of the entities of interest along with their categories being automatically sent on the communications network; c) providing rapid voice call initiation to one or more locations whose phone number is available in a geographical referenced database using the touch screen; d) providing rapid voice call initiation to the users of the cellular phone/PDA/GPS network system using the touch screen; e) providing rapid transmission of free, operator selected text messages, photographs, and video to another cellular phone using the touch screen; f) providing rapid conference calling multiple phones that are contained within the geographical referenced data base; and g) providing remote control from one cellular phone/PDA/GPS system to any of the other cellular phone/PDA/GPS system phones, including the ability to control remote cellular phones to make verbal announcements, display images, place return calls, place calls to another phone number, vibrate, change sound intensity and process and display pre-stored data, images and stored video. 2. A communication system to provide a cellular phone network for a group of participants, each of the participants having an individual portable cellular phone that includes voice communication, free and operator selected text messages, photographs and video, a CPU and a GPS navigational system that can accurately determine the location of each cellular phone, each of the cellular phones in the communications net of participants containing: said CPU and memory; a touch screen display; symbol generator in said CPU that can generate symbols that represent each of the participants' cell phones in the communication network on the display screen; a database that stores the individual telephone numbers related to each of the symbols each of which represents a participant in the communication network; cellular phone call initiating software in said CPU connected to the telephone number database and the touch screen and the symbols on the touch screen whereby touching an individual symbol will automatically initiate a cellular phone telephone call to the user represented by the symbol that includes said voice communication, free and operator selected text messages, photographs and video; and said display including databases that display geographical information that includes showing the geographical location of each of the symbols representing participants in the communication network, fixed locations, and entered items of interest. 3. A communication network that includes said participants, as in claim 2 further comprising: said software for automatically initiating a cellular phone call to a user represented by a symbol includes initiating a conference call to two or more of the participants from a base phone by touching the specific symbols of those participants that will be participating in a conference call by touching the symbol of each of those users and providing a software switch to initiate the conference call by touching the screen whereby each of the initiated conference participants will be called by the base phone to establish a conference call. 4. A communication network as in claim 3 whereby the communication network can include a large number of participants in a conference call comprising: conference call initiating software in said CPU that is made by sending a digital message to the remote cellular phones from said phone, by touching the symbol of each of the participants, of an 800 number and a participant code that cause each of the participants to call the 800 number and to enter a participant code to establish the conference call with the said phone. 5. A communication network as in claim 2 comprising: said CPU including a software program to initiate a call to one of the participants represented by a symbol on said touch screen in conjunction with a software switch displayed on said touch screen and software to initiate the cellular phone call automatically that turns the remote cellular phone on or off and generates in the receiving remote cellular phone a pre-stored message that alerts the remote cellular phone user to call the initiator. 6. A method of establishing a cellular phone communication network for designated participants, each having a similarly equipped cellular phone that includes voice communication, free and operator selected text messages, photograph and video, a CPU, a GPS navigation system and a touch screen display comprising the steps of: a) generating one or more symbols on the touch display screen, each representing a different participant that has a cellular phone that includes said voice communication, free and operator selected text messages, photograph and video, said CPU, said GPS system and a touch screen display; b) providing and storing in each of the participant cellular phones one or more cellular phone telephone numbers, each cellular phone number of which relates to a different symbol of each of the participants in the communication network; c) providing initiating cellular phone calling software in each cellular phone that is activated by touching a symbol on the touch display that automatically initiates a cellular phone call using the stored cellular phone number to the participant represented by the symbol; and d) generating a geographical location chart on said display screen to show the geographical location of each of the symbols representing the participants in the communication network by latitude and longitude. 7. The method of establishing a communication network as in claim 6 comprising the additional step of: e) providing conference call initiating software that allows each of the participants to initiate a conference call to other participants by touching each of the symbols on the touch screen representing participants who will participate in the conference call. 8. A method of establishing a communication network as in claim 6 including the step of: f) providing conference call initiating software for a large number of participants represented by the symbols on the touch screen in which each of the proposed conference call participants are established by touching the participant's symbol on the screen which causes the cellular phone initiating the conference call to transmit messages to each of the users represented by the touched symbols that tells each of the called participants through their cellular phones to call a particular 800 number to establish the conference call. 9. The method of providing a communication network as in claim 1 including the step of: providing in each of the cellular phones a remotely activatable software program for turning the cellular phone on and off and that initiates a signal from the remote cellular phone displaying a pre-stored message and to call the initiating cellular phone; and providing software that activates the remote cellular phone causing the remote cellular phone to generate said pre-stored message to the remote cellular phone user. 10. A cellular phone for use in a communication network for a plurality of participants comprising: a cellular phone transmitter and receiver for transmitting and receiving voice communication, free and operator selected text messages, photographs, and video; a small hand held portable housing containing said cellular phone transmitter and receiver; a touch display screen mounted in said housing; a modem connected to said cellular phone transmitter and receiver; a CPU connected to said cellular phone transmitter and receiver; a GPS navigation system connected to said CPU and to said cellular phone transmitter and receiver on said touch screen; a database connected to said CPU that includes a list of telephone numbers that relate to specific symbols; a symbol generator connected to said CPU and said database for generating symbols on said touch display screen; CPU software for selectively polling other participants with a cellular phone; call initiating software connected through said CPU and said telephone database and said symbol generator whereby when a user touches the symbol displayed on said touch display screen the cellular phone call is automatically initiated to the cellular phone represented by the symbol; and a geographical database connected to said CPU to provide a geographical display on said touch screen representing a defined geographical area that also displays symbols representing each of the participants by latitude and longitude. 11. A cellular phone as in claim 10, including: conference call initiating software connected to said CPU that allows the cellular phone user to initiate a conference call to a plurality of participants represented by symbols by touching each of the symbols and initiating a conference call software switch. 12. A cellular phone as in claim 10, including: conference call initiating software for large number of conference call participants that allows the user of the cellular phone to initiate a conference call to the cellular phone users represented by the symbols on the screen by touching each of the symbols representing a participant in the conference call which initiates an automatic cellular phone call to the remote cellular phone users represented by the symbols displaying a text message to call a particular 800 number to establish the conference call. 13. A cellular phone as in claim 10, including: an emergency call initiating software connected to said CPU that includes a remote cellular phone activating signal for causing a remote cellular phone that is called by touching a symbol representing the cellular phone to be called to generate and play an audio message telling the remote cellular phone user that there is an emergency and to call the cellular phone initiator. 14. A cellular phone as in claim 12, including: providing the ability to pre-establish phone conferencing nets by touching the said touch display screen at a symbolic representation of the person(s) location or by selecting the parties from a list appearing on the touch display screen and assigning them to a software drawn switch made to appear on a touch display screen; and providing the ability to conference the participants previously assigned to a net by using a software drawn switch(es) for a conference call, whereby the user touches the net software switch to initiate the call to all of the participants on the net. 15. A layered set of software drawn switches as in claim 14, including: a matrix of layered software drawn switches so that each switch that when activated on the touch display screen overlays the previously drawn matrix of switches, the matrix level of which is noted in one of the switch locations, thus providing the operator a large choice of switches in the same physical space on the touch display screen and informing the operator of the level of switches that are displayed.

FIELD OF THE INVENTION This invention relates generally to an integrated communications system using a plurality of cellular PDA/GPS phones for the management of a group of people through the use of a communications net and, specifically, provide each user with a cellular phone that has features that permit all the users to know each other's locations and status, to rapidly call and communicate data among the users by touching display screen symbols and to enable the users to easily access data concerning other users and other database information. DESCRIPTION OF RELATED ART The purpose of a communications system is to transmit information bearing signals from a source, located at one point, to a user destination, located at another point some distance away. A communications system is generally comprised of three basic elements: transmitter, information channel and receiver. One form of communication in recent years is cellular phone telephony. A network of communication cells set up around an area such as the United States allows multiple users to talk to each other, either on individual calls or on group calls. Some cellular phone services enable a cellular phone to engage in conference calls with a small number of users. Furthermore, cellular conference calls can be established through 800 number services. Cellular telephony also now includes systems that include Global Positioning System (GPS) navigation that utilizes satellite navigation. These devices thus unite cellular phone cellular technology with navigation information and computer information transmission and receipt of data. Digital SMS (Smart Message Service) and TCP/IP messages can be transmitted using cellular technology such as the various versions of GSM and CDMA or via a WiFi local area network. One implementation of these GPS location reporting cellular systems is for the data to go to a central site where the information is displayed for a person to monitor the locations of the units that have the combined GPS cellular phone. Another implementation permits the cellular phone users to also view the location of other GPS equipped units. A drawback of the current implementation is that these systems are either all on or all off. There is no way to selectively activate participants or to stop the participants from participating in the network Another drawback of the use of the current combined cellular phone PDA technology is that when using the PDA to display a map (that also may depict georeferenced businesses, homes and other facilities' locations and phone numbers), and the operator wants to place a call, the cellular phone/PDA operator is required to obtain the phone number by touching the display screen at the correct location of that entity on the map to obtain the phone number, then the operator has to memorize the phone number, then go to a different display to enter the phone number, to make the call and then, if desired, go back to the map display. Needless to say, this is a cumbersome process. Sending a text message to a location, business, home or facility that appears on a PDA map display to another cellular phone can also be a cumbersome process as the PDA operator has to find the phone number on the map display, memorize the phone number, then go to a different display to enter a text message, enter the text message, send the text message and then shift back to the map display program. Furthermore, for a phone to send data concerning a new entity of interest (car, person, tank, accident, or other entity) the operator must type in the information and the latitude and longitude of the entity. In spite of the rapid advance in cellular phone technology, it would also be desirable to actuate a remote cellular phone to annunciate an audio message to alert the remote user that there is an emergency (or for another reason) and that the calling cellular phone should be called immediately. Furthermore, it would be desirable to cause the remote phone to display a text message, photograph, video clip or video transmission, to announce the caller's name and to be able to control a remote phone and cause the remote phone to call another phone number (as an example, to automatically establish an 800 number conference call), to vibrate, or increase the loudness of an announcement without any action by the remote phone operator. The present software invention overcomes many of these problems shown in the prior art by providing a cellular phone/PDA/GPS user: a) the ability to selectively poll each of the other PDA/GPS phones to start reporting their positions and status information directly to all or selected users equipped with cellular phone/PDA communication/GPS system in the communications net so that each of the systems that the data is transmitted to is provided a display of the location, status and other information of the other users; b) the ability to exchange other entities of interest information and to assign these entities a category (car, person, tank, accident, or other entity) by touching the display screen at their locations on the map, and selecting the appropriate category switch; c) the ability to make rapid voice and data call initiation to locations, businesses, homes and facilities whose phone number is available in a georeferenced database including the cellular phone/PDA/GPS systems in a communications net by touching the display screen at the appropriate location on the PDA display and selecting a call switch; d) the ability to make rapid voice and data conference call initiation to locations, businesses, homes and facilities whose phone number is available in a georeferenced database including the cellular phone/PDA/GPS systems in a communications net by touching the display screen at the appropriate locations on the PDA display and selecting a conference call switch; e) the ability to remotely control from one cellular phone/PDA/GPS any of the other cellular phone/PDA/GPS systems phones including the ability to control remote cellular phones to make verbal prerecorded announcements, place return calls, place calls to another phone number, vibrate, execute text to speech software, change sound intensity and process and display information by touching the display screen at their location on the PDA display and selecting the appropriate switch; and f) the ability to layer a sufficient number of switches or buttons on the PDA display to perform the above functions without overlaying the map. U.S. Patent Application No. 2003/0139150 published Jul. 24, 2003 shows a portable navigation and communication system. In one embodiment, the system combines within a single enclosure a GPS satellite positioning unit, mobile telephony using cellular phone technology and personal computing capable of wired or wireless internet or intranet access using a standard operating system. The purpose of this invention is to provide portable navigation for an individual. However, to operate the device, one still needs to utilize a keypad with the telephone functions. U.S. Patent Application No. 2003/0139150 described a wireless communication operating the PDA in a conventional manner. There is no provision for displaying the location of other similarly equipped systems. There is no provision to cause other similarly equipped cellular phone PDA users to transmit their location. There is no provision for entering other entities of interest by touching the display screen at their locations on a map. There is no provision for making a telephone call by touching the display screen at a net participant's symbol to initiate automatically the telephone call to that user or by touching multiple symbols to make conference calls. There is no provision for sending text messages, photographs or videos by touching the net participant(s)' symbol(s) on the display screen to automatically send text messages, photographs or videos to that participant or participants. There is no description or disclosure of a procedure to cause digital messages to be sent to a remote cellular phone that would cause the cellular phone to make verbal announcements, increase sound intensity, vibrate or to call back or to call another phone number. There is no description of the uses of layered soft switches which confine the switches to a particular vicinity of the PDA's display screen. SUMMARY OF THE INVENTION A method and system employing cellular telephone communications to provide the location information to a group of geographically dispersed people, and to enable the rapid transmission of data concerning entities of interest to the members of the group and to coordinate the activities of the group through data and voice communications. Each of the cellular telephones includes a visual display with a touch screen, a global positioning system (GPS) receiver and navigation display, a CPU, memory, power supply, battery, microphone, speaker and commercially available software. To this is added: a) communications data and voice exchange software, b) a map database and a database of geographically referenced fixed locations including military bases, homes, businesses, government facilities, street locations and the like, each with a specified latitude and longitude, along with, if available, phone numbers that are associated with of each of these entities, c) another database with the constantly updated GPS location and status of all the software equipped cellular phone/PDA/GPS systems that are part of the communications net. Each cellular phone/PDA/GPS system is identified on the display of the other phone systems by a symbol that is generated to indicate its identity. The symbol is placed at the correct geographical location and is correlated with the map on the display. Each cellular phone/PDA/GPS System may enter other entities (locations of people, vehicles, buildings, facilities, and other entities) into its database. This information can be likewise transmitted to all the other participants on the communications net. The map, fixed entities, and cellular phone/PDA/GPS System communications net participants' latitude and longitude information is related to the display x, y display locations by a mathematical correlation algorithm. When the cellular phone/PDA/GPS System user uses his stylus or finger to touch one or more of the symbols or a location on the cellular phone display, the system's software causes the status and latitude and longitude information concerning that symbol or location to be displayed. To operate the present invention, the operator (“cellular phone one” or “phone one”) starts the system by selecting the software which causes: a) the cellular phone to initiate (if it has not already been activated), b) the GPS interface to be established, c) a map of the geographic area where the operator is located and operator's own unit symbol to appear at the correct latitude and longitude on the map, d) the locations of people, vehicles, buildings, and the like that are part of the database appear as symbols on the map, e) the system selected item read out area (which provides amplification information for the communications net participant or object that has been touched on the display screen) to appear on the display, f) an insert area that contains various varying data including: the list of net participants, a list of messages to be read, an indication of what portion of the map is being displayed in major area and other information to appear on the display, and g) a row of primary software created “soft switches” that are always present on the display. One of these soft switches when touched causes a matrix of software driven layered switches (soft switches) to appear on the display in place of the readout and insert areas. Some of these soft switches, when touched, cause the system's functions to occur. Other soft switches cause yet another layer of soft switches to appear, replacing those that were previously displayed. The operator is provided an indication of where the operator is in the layer of switches, and is able to return to the previous layer or to cause the layered switches to disappear and only the basic switches to remain. The operator can also use the phone's hardware pointing device (Navigation Pad) to control the soft switches. By using these soft switches, and hard switches that are part of the cellular phone, the operator can activate different maps, change map scales, select which fixed entities are desired to be displayed, display the information concerning the symbol the operator has touched, initiate phone voice calls, send messages (text, photographs and videos), enter symbols and information representative of other entities, view the locations and statuses of the other communications net participants, establish conference calls, pre-establish conference sub-nets that, when activated, cause all the phone numbers that are specified to be conferenced for voice, text and photograph and video communications, and transmit messages to remote phones which cause the remote phones to make calls, verbal announcements, vibrate, increase sound levels and other functions. To initialize the communications net, the cellular phone one operator selects, from a list, the other users (or all of them), that the operator desires to be part of the communications net. The system then polls the selected phones to activate and become part of the communications net. The selected phones then transmit their positions to all the other phones in the established net. Through interaction with one or more other software enabled cellular phones, symbols are generated on the operators' displays based on the participants' latitude and longitude that is exchanged between the cellular phones. The transmission of this information is based on an algorithm that considers time and or movement or upon a polling request. Each of the communication net symbols on the display represent a different cellular phone remote from cellular phone one. Each of the cellular phones has the phone numbers of all the phones in the communications net in its database. Each of the phones also has in its database the pre-established phone numbers for the fixed locations: people, buildings, facilities, military bases, and other desired locations that can be called in its database. The touch screen provided with the LCD display in the cellular phone includes x, y coordinates that are correlated with the map on the cellular phone display and the geographic location of the fixed sites and the cellular phones in the communications net. Each cellular phone can enter objects of interest by touching the display screen at the object's location on the display screen map. The operator can then assign these objects a category (car, person, tank, accident, or other category). The latitude and longitude of these objects along with their category and other information is then sent on the communications network. Because each of the receiving telephone units has software that automatically converts the received data to the correct map location, the transmitted symbols appear at the correct location without operator intervention and their category information is available by touching the symbol on the display screen. Each cellular phone/PDA/GPS has the communications hardware along with the circuitry in software to initiate a voice telephone call or transmit data messages, photographs, or videos by touching the screen with a stylus or finger at the symbol location displayed on the screen of the desired phone to be called and then selecting the “call” software switch on the display touch screen. The software will then cause the cellular phone to call to the specific phone number represented by the symbol on the screen. This is done automatically. This action alleviates completely the necessity of actually looking up a phone number and manually entering the phone numbers required to make a cellular phone call. A further benefit of the present invention is that more than one symbol can be specified to receive a cellular phone voice call and or data call, thus automatically conferencing them. The operator of the cellular phone can conference a small number of phones by touching the display screen locations of the communications net participant symbols that the operator wishes to conference by selecting a “conference” soft switch. This action will then cause the selected units to be conferenced together. The conference call can be expanded to a greater number of users by providing additional software that would conference phones by sending a digital message to the remote cellular phones from the operator cellular phone causing each of the remote cellular phones to dial a specified 800 conference call number and enter each individual phone participant code. The originator phone calls the same number and automatically enters the originator host code. Once all the phones have dialed the 800 number and entered their appropriate participant and host numbers, the conference call will be established. Furthermore, the operator of cellular phone one can pre-establish conference nets for voice and data exchange by either selecting them from a list or a table or by touching the display screen locations of the communication net participant symbols that the operator wishes to conference and selecting a “conference net” soft switch. Once the operator has done that, the software associates those communication net participants as being part of an established conference net. When the cellular phone operator chooses to call all the net participants, all the operator has to do is to select the designated software switch for that net to conference the pre-selected conference participants together. That action will then place a call to all the conferences without further action. This method of conference calling can be also used to send text messages, photographs and videos. Another embodiment of the invention can include a unique feature in which cellular phone one can send a digital message using SMS, TCP/IP or another protocol to another cellular phone on the communications net by touching a display screen symbol on the geographical screen and then selecting the appropriate software switch to transmit a digital message that would then remotely activate a program in the remote cellular phone to play a recorded audio file to announce an emergency and that a call to cellular phone one is required immediately. Since each of the remote cellular phones has the same software as cellular phone one and includes a PDA and the ability to receive digital messages, the ability to control remote cellular phones to make verbal announcements, display images, place return calls, place calls to another phone number, vibrate, change sound intensity and process and display pre-stored data, images and video can be achieved. In accordance with the present invention, a multiple cellular phone communication network is set up using the invention. Each cellular phone contains the same software and circuitry that includes cellular phone technology, GPS navigation technology, and a PDA for displaying maps, georeferenced symbols, and data concerning symbols of interest and software created soft switches, transmitting and receiving digital SMS, TCP/IP and other protocol messages. To establish each other's communication net IP addresses, the cellular phones first exchange SMS messages (or use another method) that identifies their IP addresses. Each phone then transmits to all others its location and status in accordance with an established algorithm that is based on time and or movement. Each cellular phone is also able to poll the other cellular phones to transmit their locations. Each user is able to transmit to all the other users: text messages, photographs and videos. Using the present invention, a cellular telephone network can be set up in which all of the parties in the network have almost automatic and instant access to and status of any and all other parties in the network by touching the display screen symbol of the party he desires to initiate voice and data calls, thus, instantly activating the calls. This is an immense time saver in dealing with a cellular phone network for all the parties combined. It is an object of this invention to provide an improved cellular telephone communication network among a plurality of cellular phones for greatly increasing the call up and initiation speed of each of the cellular phones with each other. And yet another object of this invention is to enable each participant to automatically exchange IP addresses using SMS or another digital message format. And yet another object of this invention is to enable each participant in the communications net to poll the other net participants to report or cease reporting their locations and status on the communication net. And yet another object of this invention is to enable each participant in the communications net to be able to easily transmit entities of interest to the other participants of the net by touching the display at the entities' location on the map and causing a symbol to be entered and then entering the entities' category information. And yet another object of this invention is to provide for initiating a cellular phone telephone call to another phone by touching the other phone's symbol on the screen of the cellular phone, which automatically activates the telephone call. And yet another object of this invention is to provide a cellular phone network that provides for instant conference calling among a plurality of cellular phones by touching the screen of specific symbols for initiating the calls. And yet another object of this invention is to provide a cellular phone network that provides for instant conference voice, text, photographs and video exchange by pre-establishing conferencing sub-nets and the subsequent activation of one of those sub-nets to establish a conference call. And yet still another object of this invention is to provide a cellular phone that allows for remote alarm activation on another cellular phone to cause a remote cellular phone to make verbal announcements, display images, place return calls, place calls to another phone number, vibrate, change sound intensity and process and display pre-stored data, images and video. In accordance with these and other objects which will become apparent hereinafter, the instant invention will now be described with particular reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a front plan view of a cellular phone/PDA and display in accordance with the present invention. FIG. 2 shows a front plan view of the cellular phone/PDA of FIG. 1 with a different display. FIG. 3 shows a flow chart of the operation of the present invention. DETAILED DESCRIPTION Referring now to the drawings and, in particular, FIG. 1, the present invention is shown generally at 10 that includes a small handheld cellular phone/PDA communications system in housing 12 that includes an on/off power switch 19, a microphone 38, and an LCD display 16 that is also a touch screen system. The small area 16a is the Navigation Bar that depicts the telephone, GPS and other status data and the active software. With the touch screen system, the screen symbols are entered through GPS inputs or by the operator using a stylus or finger 14 by manipulatively directing the stylus or finger 14 to literally touch display screen 16. The soft switches displayed on the screen are likewise activated by using a stylus or finger 14 and physically and manipulatively directing the stylus or finger to literally touch display screen 16. The display x, y coordinates of the touched point are known by a CPU in the PDA section of the communication system that can coordinate various information contained in the PDA portion relative to the x, y coordinate position on the screen. Inside housing 12 is contained the conventional cellular phone elements including a modem, a CPU for use with a PDA and associated circuitry connected to a speaker 24 and a microphone 38. A GPS navigational system that can determine the latitude and longitude of the cellular phone can be internal or external to the housing 12. PDA/cellular phone units such as these are currently on sale and sold as a complete unit (or with an external connected GPS) that can be used for cellular telephone calls and sending cellular SMS and TCP/IP or other messages using the PDA's display and computer. The GPS system is capable of determining the latitude and longitude and through SMS, TCP/IP, WiFi or other digital messaging software, to also transmit this latitude and longitude information to other cellular phones via cellular communications, WiFi or radio. The unit includes a pair of cellular phone hardware activating buttons 20 to turn the cellular phone on and 22 to turn the cellular phone off. Navigation Pad actuator 18 is similar to a joy or force stick in that the actuator 18 manually provides movement commands that can be used by the PDA's software to move a cursor. Switches 26 and 28 are designed to quickly select an operator specified software program. Device 24 is the system's speaker. Device 38 is the system's microphone. Switch 19 at the top left of the unit is the power on and power off switch. The heart of the invention lies in the software applications provided in the system. Mounted inside housing 12 as part of the PDA is the display function screen and the CPU. The CPU includes databases that provide for a geographical map and georeferenced entities that is shown as display portion 16b that includes as part of the display various areas of interest in the particular local map section. When looking at display 16, the software switches which appear at the very bottom of the display 16d are used to control many of the software driven functions of the phone. The software drawn and controlled switches are activated through the operator's use of the Navigation Pad 18, or a small track ball, force stick or similar hardware pointing device. Alternatively, the operator may chose to activate the software switch matrix by touching the screen with his finger or stylus at the switches' locations. When some of the software switches are activated, it will cause yet different software switches to appear. The bar display 16d shows the software switches “ZM IN, (zoom in)” “ZM OT (zoom out),”, “CENT (center)” “GRAB, (pan/grab)” at the bottom of the screen. These software switches are for the operator to perform these functions. The “SWITH (switch)” software switch at the lower right causes the matrix of layered software switches to appear above the bottom row of switches. Through use of the software switches, one can also manipulate the geographical map or chart display. When looking at FIG. 1, permanent geographical locations and buildings are shown. For example, the police station is shown and when the symbol is touched by the stylus or finger, the latitude and longitude of the symbol's location, as shown in display section 16c, is displayed at the bottom left of the screen. The bottom right side of display 16c is a multifunction inset area that can contain a variety of information including: a) a list of the communication link participants; b) a list of received messages; c) a map, aerial photograph or satellite image with an indication of the zoom and off set location of the main map display, which is indicated by a square that depicts the area actually displayed in the main geographical screen 16b; d) applicable status information; and e) a list of the communication net participants. Also shown on the display screen 16, specifically the geographical display 16b, is a pair of different looking symbols 30 and 34, a small triangle and a small square, which are not labeled. These symbols 30 and 34 can represent communication net cellular phone users in the displayed geographical area that are part of the overall cellular phone communications net used in this invention wherein each of the users has a similar cellular phone to the one shown in FIG. 1. The latitude and longitude of symbol 30 is associated within a database along with a specific phone number. The screen display 16b, which is a touch screen, provides x and y coordinates of the screen 16b to the CPU's software. The software has an algorithm that relates the x and y coordinates to latitude and longitude and can access a communications net participant's symbol or an entity's symbol as being the one closest to that point. In order to initiate a telephone call to the cellular phone user represented by symbol (triangle) 30 at a specific GPS provided latitude and longitude which has been sent to the cellular phone shown in FIG. 1, the operator or initiator of what we call cellular phone one in FIG. 1 can take the stylus or finger 14, touch the triangle 30 with the stylus or finger, and then touch a “call” software switch from a matrix of displayed switches that will overlay the display area 16c and immediately the cellular phone one will initiate a cellular phone telephone call to the cellular phone user at the location shown that represents symbol 30. A second cellular phone user is represented by symbol 34 which is a small square but could be any shape or icon to represent an individual cellular phone unit in the display area. The ring 32 around symbol 30 indicates that the symbol has been touched and that a telephone call can be initiated by touching the soft switch that says “call.” When this is done, the telephone call is placed. Another type of symbolic display can indicate that the call is in effect. Furthermore, the operator of cellular phone one can call the police station or other locations, buildings, or facilities (whose phone numbers are stored in the database) by touching them on the display screen using the stylus or his finger and then the call switch. Additionally, the operator can touch both symbol 34 and symbol 30 and can activate a conference call between the two cellular phones and users represented by symbols 30 and 34. Again, a symbolic ring around symbol 34 indicates that a call has been initiated. The system shown in FIG. 1 can also initiate a telephone conference call for a small number of phones using a stylus or finger contact to touch all the displayed symbols on display 16 that the initiator desires to conference and then selecting the conference call soft switch. The operator can also pre-establish a conference sub-net that the operator desires to be able to rapidly call. The operator performs this task by touching the symbols or by selecting participants from a list or a matrix of the participant addresses and assigning the participants to a net software switch. When the operator desires to place a conference call to these participants, the operator simply touches the net soft switch associated with this group. Software is provided in the unit that mimics setting up a normal small conference call from “phone one” to each of the cellular phones the user had indicated by touching their symbols or selecting their sub-net soft switch on the screen. Once the first call is complete, the party will be automatically put on hold and other callers will be called or answered in sequence and put on hold until all the parties are on line at which time the conference call will be announced at each phone. As each participant is called, the phone will announce that a conference call requested by cellular phone one is in progress. This will all be done by software. If a conference call is desired that includes more than a small number of phone users, the use of an 800 number conferencing service is required. The initiator or operator of cellular phone one would select the “conference 800” call software switch and then use the stylus or finger to touch the cellular phone users' symbols to whom the calls are to be placed. For example, 50 users are desired on a conference call. The cellular phone would send out a SMS or TCP/IP message to all of the cellular phone displays that requests each cellular phone to call an 800 number (the given number for a conference call) to conference with cellular phone one. Each individual cellular phone user at that point in time would then be verbally notified that a conference call was requested. When the user selected the “accept” software switch, the phone would then call the 800 number and enter its conference participant code. Another feature available in the cellular phone/PDA system shown in FIG. 1 is its ability to activate a remote cellular phone to make verbal announcements, display images, place return calls, place calls to another phone number, vibrate, change sound intensity and process and display pre-stored data, images and video. As an example, on the PDA screen display 16, a software switch will be provided that would allow cellular phone one to call in an emergency situation and that would basically initiate an emergency audio response call. Using the stylus or finger again, a symbol such as 30 would be touched with the stylus or finger indicating a call to be made. The software switch labeled “call” would cause other software switches to appear, one of which would be “call provide emergency audio response” which when touched by the stylus or finger 14 would cause the cellular phone one system to automatically call the telephone number represented by symbol 30. The cellular phone 30 includes software that when it receives the SMS or TCP/IP message, can activate an audio message that announces “emergency please call cellular phone one immediately.” The announcement would be done through the cellular phone speaker. Thus, the system is capable of initiating a cellular phone call by touch only, initiating conference call by touch only and activating a remote cellular phone to announce an emergency and other messages and elicit the audio response in the remote cellular phone by touch only. Referring now to FIG. 2, the same cellular phone/PDA 10 is shown with the soft switch matrix displayed at 16cc and 16d. The cellular phone/PDA is capable of an alternative method of contacting the participants. As shown in FIG. 2 and display 16cc, a plurality of squares is displayed having letters and numbers, each square of which indicates a different participant such as “A1SQD.” Also, on the right hand side, top line is a switch option called “call.” The bottom line 16dd shows ZM IN, ZM OUT, CENT, GRAB and SWIT. Using this alternative telephone method, the initiator can touch individual squares, each having a reference to a participant to initiate one call or a conference call with all of the parties. These can also be joined in a single NET 1 as shown. Subsequent phone calls with the particular designated parties or participants established with NET 1 can subsequently be initiated just by touching NET 1 with the stylus or with a finger. The displayed information can be layered with a plurality of “NETS” on a next layer for contacting groups of participants in each NET. This is used in lieu of the screen symbols for conference calls. Referring now to FIG. 3, a flow chart is shown of the activities provided by the present invention and the methodology. First, we provide a cellular phone that includes PDA computer technology and a GPS navigation system that provides to the PDA the location of the cellular phone in latitude and longitude at all times. The cellular phone includes an LCD display with touch screen features for use with a stylus or finger. The communication device is also given a database that includes a geographical display on the LCD display and software that coordinates the x and y coordinates on the LCD display touch screen with the geographical display. There is also software that places symbols on the geographical display that represent other cellular phone users that are part of the communications net. All the participant's cellular phones that are a part of the communications net include an integrated or electronically connected GPS navigational system. Each phone can call the other cellular phones and request that they broadcast their latitude and longitude locations and status information. Each cellular phone can enter other entities of interest and assign each of them a category (car, person, tank, accident, or other category). The latitude and longitude of each of these entities along with each category is then sent on the communications network. Each phone can also have the latitude and longitude and phone numbers of fixed (geographically referenced fixed locations including: restaurants, gas stations, hospitals, fire departments, military bases, homes, businesses, government facilities, street locations, and the like) are also contained in the data base and displayed on the screen. Therefore, the present invention can provide a cellular phone PDA GPS system that includes a geographical display that shows one or more other cellular phone users symbolically displayed on the screen and also entered entities that each of the cellular phone users consider to be items of interest, along with pre-established points of interest (geographical referenced fixed locations including: restaurants, gas stations, hospitals, fire departments, military bases, homes, businesses, government facilities, street locations, and the like). The present invention also includes a database that has the specific cellular phone telephone numbers of each of the displayed symbols thus providing a relationship between the symbol, its location on the geographical screen and the stored memory phone number. There is also a software program that allows the operator of cellular phone one to touch one of the symbols representing a phone user on the display screen and to initiate a call by touching the appropriate switch with a stylus or finger at which time the software will automatically retrieve the designated symbolic phone telephone number from memory and will initiate instantly a telephone call to the cellular phone number that is associated with the symbol. This is all done by merely touching the symbol representing the phone in the database and touching the “call” soft switch. In addition, with multiple cellular phone users present, the operator of cellular phone one can use the stylus or finger and touch more than one cellular phone user's symbol and then touch a software switch that says “conference call” wherein the software will initiate and establish conference calls with all of the designated cellular phone users by the touch of a stylus or finger or by selecting a pre-established participant conference net switch. In the event that there are more than a small number of phone users in the area that need to be established on a conference call, because of the technological limitations of conference calls on cellular phones, the system will send a different message that causes the remote cellular phone to call a specific 800 conference number that can establish a much larger number of conference callers. Thus, if the user selects to conference more than an established number of phone users for a conference call, the software will indicate that the 800 number software switch is to be utilized. In addition the operator of cellular phone one can address text messages, photographs and video for transmission to one or more net participants by either touching their symbols and selecting the appropriate soft switch or selecting the appropriate call net. Another important feature of the present invention is that the operator or initiator of cellular phone one can by touching a switch on the display, send through the PDA system, a signal and digital message to all the cellular phones in the communications net or to designated cellular phone(s), represented by their symbols on the geographic display, an emergency message which requires a response. When received, the software in the remote cellular phone causes the remote cellular phone to initiate an audio message to the cellular phone user that there is an emergency (or another message) and to call the initiator immediately. This is accomplished by the message sent from cellular phone one to the software in the remote cellular phone(s). In summary, the present invention provides for expeditious data exchange and cellular phone calls to one or more users by merely touching the display screen location of a remote cellular phone user's symbol to initiate the call. Other features include conference calling by stylus or finger and a rapid emergency remote activation and causing a remote phone to: annunciate various pre-established messages, execute text to speech software, increase its volume level, vibrate, show photographs, or show videos. The instant invention has been shown and described herein in what is considered to be the most practical and preferred embodiment. It is recognized, however, that departures may be made there from within the scope of the invention and that obvious modifications will occur to a person skilled in the art.

<SOH> FIELD OF THE INVENTION <EOH>This invention relates generally to an integrated communications system using a plurality of cellular PDA/GPS phones for the management of a group of people through the use of a communications net and, specifically, provide each user with a cellular phone that has features that permit all the users to know each other's locations and status, to rapidly call and communicate data among the users by touching display screen symbols and to enable the users to easily access data concerning other users and other database information.

<SOH> SUMMARY OF THE INVENTION <EOH>A method and system employing cellular telephone communications to provide the location information to a group of geographically dispersed people, and to enable the rapid transmission of data concerning entities of interest to the members of the group and to coordinate the activities of the group through data and voice communications. Each of the cellular telephones includes a visual display with a touch screen, a global positioning system (GPS) receiver and navigation display, a CPU, memory, power supply, battery, microphone, speaker and commercially available software. To this is added: a) communications data and voice exchange software, b) a map database and a database of geographically referenced fixed locations including military bases, homes, businesses, government facilities, street locations and the like, each with a specified latitude and longitude, along with, if available, phone numbers that are associated with of each of these entities, c) another database with the constantly updated GPS location and status of all the software equipped cellular phone/PDA/GPS systems that are part of the communications net. Each cellular phone/PDA/GPS system is identified on the display of the other phone systems by a symbol that is generated to indicate its identity. The symbol is placed at the correct geographical location and is correlated with the map on the display. Each cellular phone/PDA/GPS System may enter other entities (locations of people, vehicles, buildings, facilities, and other entities) into its database. This information can be likewise transmitted to all the other participants on the communications net. The map, fixed entities, and cellular phone/PDA/GPS System communications net participants' latitude and longitude information is related to the display x, y display locations by a mathematical correlation algorithm. When the cellular phone/PDA/GPS System user uses his stylus or finger to touch one or more of the symbols or a location on the cellular phone display, the system's software causes the status and latitude and longitude information concerning that symbol or location to be displayed. To operate the present invention, the operator (“cellular phone one” or “phone one”) starts the system by selecting the software which causes: a) the cellular phone to initiate (if it has not already been activated), b) the GPS interface to be established, c) a map of the geographic area where the operator is located and operator's own unit symbol to appear at the correct latitude and longitude on the map, d) the locations of people, vehicles, buildings, and the like that are part of the database appear as symbols on the map, e) the system selected item read out area (which provides amplification information for the communications net participant or object that has been touched on the display screen) to appear on the display, f) an insert area that contains various varying data including: the list of net participants, a list of messages to be read, an indication of what portion of the map is being displayed in major area and other information to appear on the display, and g) a row of primary software created “soft switches” that are always present on the display. One of these soft switches when touched causes a matrix of software driven layered switches (soft switches) to appear on the display in place of the readout and insert areas. Some of these soft switches, when touched, cause the system's functions to occur. Other soft switches cause yet another layer of soft switches to appear, replacing those that were previously displayed. The operator is provided an indication of where the operator is in the layer of switches, and is able to return to the previous layer or to cause the layered switches to disappear and only the basic switches to remain. The operator can also use the phone's hardware pointing device (Navigation Pad) to control the soft switches. By using these soft switches, and hard switches that are part of the cellular phone, the operator can activate different maps, change map scales, select which fixed entities are desired to be displayed, display the information concerning the symbol the operator has touched, initiate phone voice calls, send messages (text, photographs and videos), enter symbols and information representative of other entities, view the locations and statuses of the other communications net participants, establish conference calls, pre-establish conference sub-nets that, when activated, cause all the phone numbers that are specified to be conferenced for voice, text and photograph and video communications, and transmit messages to remote phones which cause the remote phones to make calls, verbal announcements, vibrate, increase sound levels and other functions. To initialize the communications net, the cellular phone one operator selects, from a list, the other users (or all of them), that the operator desires to be part of the communications net. The system then polls the selected phones to activate and become part of the communications net. The selected phones then transmit their positions to all the other phones in the established net. Through interaction with one or more other software enabled cellular phones, symbols are generated on the operators' displays based on the participants' latitude and longitude that is exchanged between the cellular phones. The transmission of this information is based on an algorithm that considers time and or movement or upon a polling request. Each of the communication net symbols on the display represent a different cellular phone remote from cellular phone one. Each of the cellular phones has the phone numbers of all the phones in the communications net in its database. Each of the phones also has in its database the pre-established phone numbers for the fixed locations: people, buildings, facilities, military bases, and other desired locations that can be called in its database. The touch screen provided with the LCD display in the cellular phone includes x, y coordinates that are correlated with the map on the cellular phone display and the geographic location of the fixed sites and the cellular phones in the communications net. Each cellular phone can enter objects of interest by touching the display screen at the object's location on the display screen map. The operator can then assign these objects a category (car, person, tank, accident, or other category). The latitude and longitude of these objects along with their category and other information is then sent on the communications network. Because each of the receiving telephone units has software that automatically converts the received data to the correct map location, the transmitted symbols appear at the correct location without operator intervention and their category information is available by touching the symbol on the display screen. Each cellular phone/PDA/GPS has the communications hardware along with the circuitry in software to initiate a voice telephone call or transmit data messages, photographs, or videos by touching the screen with a stylus or finger at the symbol location displayed on the screen of the desired phone to be called and then selecting the “call” software switch on the display touch screen. The software will then cause the cellular phone to call to the specific phone number represented by the symbol on the screen. This is done automatically. This action alleviates completely the necessity of actually looking up a phone number and manually entering the phone numbers required to make a cellular phone call. A further benefit of the present invention is that more than one symbol can be specified to receive a cellular phone voice call and or data call, thus automatically conferencing them. The operator of the cellular phone can conference a small number of phones by touching the display screen locations of the communications net participant symbols that the operator wishes to conference by selecting a “conference” soft switch. This action will then cause the selected units to be conferenced together. The conference call can be expanded to a greater number of users by providing additional software that would conference phones by sending a digital message to the remote cellular phones from the operator cellular phone causing each of the remote cellular phones to dial a specified 800 conference call number and enter each individual phone participant code. The originator phone calls the same number and automatically enters the originator host code. Once all the phones have dialed the 800 number and entered their appropriate participant and host numbers, the conference call will be established. Furthermore, the operator of cellular phone one can pre-establish conference nets for voice and data exchange by either selecting them from a list or a table or by touching the display screen locations of the communication net participant symbols that the operator wishes to conference and selecting a “conference net” soft switch. Once the operator has done that, the software associates those communication net participants as being part of an established conference net. When the cellular phone operator chooses to call all the net participants, all the operator has to do is to select the designated software switch for that net to conference the pre-selected conference participants together. That action will then place a call to all the conferences without further action. This method of conference calling can be also used to send text messages, photographs and videos. Another embodiment of the invention can include a unique feature in which cellular phone one can send a digital message using SMS, TCP/IP or another protocol to another cellular phone on the communications net by touching a display screen symbol on the geographical screen and then selecting the appropriate software switch to transmit a digital message that would then remotely activate a program in the remote cellular phone to play a recorded audio file to announce an emergency and that a call to cellular phone one is required immediately. Since each of the remote cellular phones has the same software as cellular phone one and includes a PDA and the ability to receive digital messages, the ability to control remote cellular phones to make verbal announcements, display images, place return calls, place calls to another phone number, vibrate, change sound intensity and process and display pre-stored data, images and video can be achieved. In accordance with the present invention, a multiple cellular phone communication network is set up using the invention. Each cellular phone contains the same software and circuitry that includes cellular phone technology, GPS navigation technology, and a PDA for displaying maps, georeferenced symbols, and data concerning symbols of interest and software created soft switches, transmitting and receiving digital SMS, TCP/IP and other protocol messages. To establish each other's communication net IP addresses, the cellular phones first exchange SMS messages (or use another method) that identifies their IP addresses. Each phone then transmits to all others its location and status in accordance with an established algorithm that is based on time and or movement. Each cellular phone is also able to poll the other cellular phones to transmit their locations. Each user is able to transmit to all the other users: text messages, photographs and videos. Using the present invention, a cellular telephone network can be set up in which all of the parties in the network have almost automatic and instant access to and status of any and all other parties in the network by touching the display screen symbol of the party he desires to initiate voice and data calls, thus, instantly activating the calls. This is an immense time saver in dealing with a cellular phone network for all the parties combined. It is an object of this invention to provide an improved cellular telephone communication network among a plurality of cellular phones for greatly increasing the call up and initiation speed of each of the cellular phones with each other. And yet another object of this invention is to enable each participant to automatically exchange IP addresses using SMS or another digital message format. And yet another object of this invention is to enable each participant in the communications net to poll the other net participants to report or cease reporting their locations and status on the communication net. And yet another object of this invention is to enable each participant in the communications net to be able to easily transmit entities of interest to the other participants of the net by touching the display at the entities' location on the map and causing a symbol to be entered and then entering the entities' category information. And yet another object of this invention is to provide for initiating a cellular phone telephone call to another phone by touching the other phone's symbol on the screen of the cellular phone, which automatically activates the telephone call. And yet another object of this invention is to provide a cellular phone network that provides for instant conference calling among a plurality of cellular phones by touching the screen of specific symbols for initiating the calls. And yet another object of this invention is to provide a cellular phone network that provides for instant conference voice, text, photographs and video exchange by pre-establishing conferencing sub-nets and the subsequent activation of one of those sub-nets to establish a conference call. And yet still another object of this invention is to provide a cellular phone that allows for remote alarm activation on another cellular phone to cause a remote cellular phone to make verbal announcements, display images, place return calls, place calls to another phone number, vibrate, change sound intensity and process and display pre-stored data, images and video. In accordance with these and other objects which will become apparent hereinafter, the instant invention will now be described with particular reference to the accompanying drawings.

20040921

20060418

20060323

61737.0

H04Q700

MOE, AUNG SOE

CELLULAR PHONE/PDA COMMUNICATION SYSTEM

SMALL

ACCEPTED

H04Q

ACCEPTED

Device for control of display of video frames and method for control of display of video frames

The present invention relates to a device for control of display of video frames and a method for control of display of video frames, used in digital decoders/receivers of television signal, to which the signal is drawn in an analogue form.

1. A device for control of display of video frames comprising a receiving block for receiving a first analogue video signal of a first format; a conversion block for conversion of the first analogue signal of the first format into a digital signal and connected to the receiving block; a buffer controller of frames included in the digital signal connected to the conversion block and having frame buffers, a decoding frame controller and a displaying frame controller; a video coder for transforming the digital signal into a second analogue signal of a second format; a receiver for displaying the second analogue signal of the second format; and a processor for data processing and controlling the receiving block, the conversion block, the buffer controller, the video coder and the receiver. 2. A method for control of display of video frames comprising the steps of: creating at least three frame buffers; setting a current decoder buffer chosen from the frame buffers; fetching of data of frames from a first analogue video signal of a first format; temporarily storing the data of the frames in the current decoder buffer; setting a display buffer chosen from the frame buffers; and reading data of a display frame from the display buffer and displaying the frame in a second video. 3. The method according to claim 2, wherein the frame buffers are organized in a two-way list and wherein the last element of the two-way list is linked to the first element of the two-way list. 4. The method according to claim 2, wherein the step of fetching and the storing of the data of the frames comprises the steps of setting the current decoder buffer, to which the data of the frames will be decoded, to a first free buffer from the frame buffers; awaiting for a bottom vertical synchronization signal in the first analogue video signal of the first format; checking if a next buffer, in relation to the current decoder buffer, is being displayed, after the bottom vertical synchronization signal is detected; setting the next buffer as the current decoder buffer when the next buffer is not being displayed; detecting a top vertical synchronization signal in the first analogue video signal of the first format; decoding of the data of the frame to the current decoder buffer; and returning to the awaiting for the bottom vertical synchronization signal in the input video signal. 5. The method according to claim 2, wherein the step of reading and displaying data comprises the steps of awaiting for an appearance of a bottom vertical synchronization signal in an analogue output video signal; setting a previous buffer in relation to the current decoder buffer as the display buffer after appearance of a bottom vertical synchronization signal; awaiting for a top synchronization signal in the output video signal; displaying the display buffer after detecting the top vertical synchronization signal in the output video signal; and returning to the awaiting for the bottom vertical synchronization signal in the output video signal. 6. A method for control of display of video frames comprising the steps of: applying at least three frame buffers; setting a current decoder buffer chosen from the frame buffers; fetching of data of a frame from a first analogue video signal; awaiting for a bottom vertical synchronization signal in the first analogue video signal; checking if a next buffer, in relation to the current decoder buffer, is being displayed, after the bottom vertical synchronization signal is detected; setting the next buffer as the current decoder buffer when the next buffer is not being displayed; detecting a top vertical synchronization signal in the first analogue video signal; decoding of the data of the frame to the current decoder buffer; temporarily storing the data of the frame in the current decoder buffer; returning to the awaiting for the bottom vertical synchronization signal in the first analogue video signal; awaiting for an appearance of a bottom vertical synchronization signal in an analogue output video signal; setting a previous buffer in relation to the current decoder buffer as the display buffer after appearance of the bottom vertical synchronization signal; awaiting for a top synchronization signal in the analogue output video signal; displaying the display buffer after detecting the top vertical synchronization signal in the analogue output video signal; and returning to the awaiting for the bottom vertical synchronization signal in the analogue output video signal, wherein the fetching-decoding and displaying processes are run concurrently and communicate with each other. 7. The method according to claim 6, wherein the frame buffers are organized in a two-way list and wherein the last element of the two-way list is linked to the first element of the two-way list.

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to Polish Application No. P-362631, filed Oct. 6, 2003, the contents of which are incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for control of display of video frames and a method for control of display of video frames, used in digital decoders/receivers of television signal, in which the signal is received in an analogue form, and then, after conversion into a digital signal, it is processed in the decoder/receiver (e.g. OSD ‘On-Screen Display’ functions are applied). Next it is converted to an analogue format, which is transmitted to a receiver, for example a TV set. 2. Brief Description of the Background of the Invention Including Prior Art The methods of controlling display of video signal frames, known from the prior art, can be divided into three groups. The first group uses a single frame buffer, and the input of video signal (refresh frequency timer) is not synchronized with the output. The drawback of this solution are the interferences, which appear during the displaying of video frames. They appear, for instance, as a shift of the top part of the picture in relation to the bottom part. The second solution consists in applying a single frame buffer and synchronization of the input signal timers with the output signal. Although interferences occurring in the first method do not appear here, it is still necessary to synchronize the timers. Moreover, there appear problems related to switching among input signals with different synchronization frequencies/phases. The third method, called “back buffering” or “double buffering”, requires two frame buffers. Data are fetched into the first one, and next they are copied to the second one. The contents of the second buffer are displayed. A disadvantage of this solution is the necessity of copying large amounts of data. The U.S. Pat. No. 5,446,496 presents a solution, in which the frequency of video frames is converted. The output frequency in this solution must be lower than the input frequency. Moreover, a single frame buffer is used for the conversion, which—during considerable discrepancies between input and output frame frequencies—may lead to the loss of many video signal frames. This is due to the fact, that the currently displayed data cannot be overwritten. SUMMARY OF THE INVENTION Purposes of the Invention It is the object of this invention to eliminate the interferences and allowing a conversion of video frames frequency, in such a way, that the output frequency can be either lower or higher than the input frequency. This and other objects and advantages of the present invention will become apparent from the detailed description, which follows. BRIEF DESCRIPTION OF THE INVENTION A device for control of display of video frames, according to the present invention, comprises a receiving block for receiving a first analogue video signal or an input video signal, a conversion block for conversion of the first analogue signal, of a first format, into a digital signal and connected to the receiving block, a buffer controller of frame buffers, connected to the conversion block, the buffer controller comprising three modules, (a) buffers linked together, (b) a decoding frame controller and (c) a displaying frame controller, a video coder for transforming the output digital signal into an output analogue signal or an analogue signal of a second format, a receiver for displaying the analogue signal of a second format and a processor for data processing and controlling the receiving block, the conversion block, the buffer controller, the video coder and the receiver. In the method, according to the present invention, two processes are initiated. The first one controls fetching and decoding of frames from the source of the signal recorded in a first video format, and storing them in the chosen frame buffers. The second one controls displaying frames, stored in frame buffers, where the displaying preferably takes place in a second video format. These processes communicate between each other, setting the moment, which is related to signals frequencies, and place, being the chosen buffer, for the fetching and displaying of video frames with the application of at least three video frame buffers. The method presented here applies to processing of video frames, which are read from an analogue video signal source. These frames are processed and then displayed by an analogue signal receiver, such as a television set. Data that are needed for processing and displaying the frames are transmitted in the source signal. They may, for instance, comply with the ITU-R BT.601-5 or ITU-R BT.656-4 specifications. The method for control of display of video frames comprises applying at least three frame buffers, fetching frames from signal data, temporarily storing the frames of a first video format in the first buffer chosen from the buffers and reading and displaying the frames in a second video format. The frame buffers can be organized in a two-way list form, in which the first element of the list has a pointer to the last element and the last element of the list has a pointer to the first element of the list. The fetching and decoding of the frames favorably starts with setting the current decoder buffer pointer, to which the a frame will be decoded, to the first buffer of the two-way list of buffers, awaiting for a bottom vertical synchronization signal from an input video signal, checking if a next buffer, in relation to the current decoder buffer, is being displayed, when the bottom vertical synchronization signal is detected, setting the next buffer as the current decoder buffer when the next buffer is not displayed, detecting a top vertical synchronization signal in the analogue input signal data, decoding data to the current decoder buffer and awaiting for the next bottom vertical synchronization signal from the input video signal. The reading and displaying of data favorably starts from setting the first buffer from a list of buffers as the current displayed buffer and then awaiting for an appearance of a bottom vertical synchronization signal in an analogue output video signal. After such signal is detected, setting the previous buffer in relation to the current decoder buffer as the current displayed buffer and, after the appearance of the top vertical synchronization signal, displaying the current display buffer, and returning to the awaiting for the bottom vertical synchronization signal in the output video signal. According to the method, data is buffered in the list of frame buffers used in the device, which temporarily store the received video frames. Such list consists of at least three buffers, where each of them stores a single video frame. The present invention allows avoiding problems with the synchronization of the input signal frame timer with the output signal frame timer. The received data are processed in such a way, that the reading does not conflict with the writing, and no interferences are introduced to the output analogue signal. Moreover, contrary to the known solutions, picture interference is avoided, as is the need for the transfer of large amount of data between separate frame buffers. Thanks to data buffering in the queue of the frame buffers, and to the method of controlling it, problems with synchronization of the input signal frame timer with the of output signal frame timer, can be also avoided. BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings one of the possible embodiments of the present invention is shown, where: FIG. 1 is a typical analogue video signal; FIG. 2 is a schematic diagram of a device for control of display of video frames; FIG. 3 is a shift of video frame synchronizing signals; FIG. 4 is a flow chart of a procedure of decoding signal frames; FIG. 5 is a flow chart of a procedure of displaying signal frames; FIG. 6 is a flow chart of a procedure of organizing video signal frame buffers; FIG. 7 is a diagram of steps of fetching and displaying of frames when an input frequency is higher than an output frequency; and FIG. 8 is a diagram of steps of fetching and displaying of frames when an input frequency is lower than an output frequency. DESCRIPTION OF INVENTION AND PREFERRED EMBODIMENT As shown in FIG. 1—illustrating an analogue video signal—data intended to be displayed are sent together with control signals to the signal receiver. The fragment 106 of the analogue video signal corresponds to a single horizontal line of a picture. Its individual parts represent: a horizontal synchronization (HSync) 101, which denotes a shift to the next line, a horizontal front porch 102, a horizontal back porch 103, a horizontal blank time 104 and time 105, at which information about the contents of a given line is transferred. As shown in signal part 107, after displaying all picture lines, the analogue video signal transmits the information about a vertical synchronization 108 to the signal receiver. Such information consists of three parts: a vertical front porch 109, a vertical synchronization (VSync) 110, which denotes setting of a current location of picture display in the left hand top corner and a vertical back porch 111. A device for control of display of video frames, for which the method of controlling display of video frames described in the present invention is intended, is shown in FIG. 2. This device is a television signal receiver/decoder, which fetches television data from an analogue video signal. A receiving block 201 of the analogue video signal transmits data read from the analogue signal to a conversion block 202, where conversion of the analogue signal into a digital signal takes place. After the conversion, data are transmitted to a buffers controller 203, which consists of a decoding controller 203a, buffers 203b and a displaying controller 203c. The buffer controller 203 controls writing of the data in the buffers 203b, reading of the data from the buffers 203b and transmitting the data form the buffers 203b to a video coder 204, which transforms the digital signal into an analogue signal, which is next transmitted to a receiver 205, for example a television set. The whole process of data processing is controlled by the processor 206 of the television receiver/decoder. In addition, data can be further processed in the buffers. A method for control of display of video frames, described in the present invention, solves the problem of shifting synchronizing signals of input and output video signals and eliminates picture interferences, which may occur, when the frequency of the input video frames differs from a frequency of the output frames. In the case when the input frequency is higher and frame buffers record more data than can be transferred to the output, certain frames will be omitted (depending on the frequency difference) in order to avoid any interference in the picture display. However, if the input frames frequency is lower than the output frequency, some frames will—if there is such need—be displayed more than once. Typical frame frequencies for a PAL signal are 25 frames per second (50 VSYNC signals). For NTSC, the frequency is 29.97 frames per second (59.94 VSYNC signals). FIG. 3 illustrates an example of a shift between the input and output video signals of the same frequency. Control of the input data by the output timer would create interferences, which could appear to the user as a picture consisting half of one frame, and half of the next one. A flow chart of a procedure of decoding frames is shown in FIG. 4. This procedure controls decoding of a picture frame and writing it the to selected frame buffer. The procedure starts in step 401. Its first task, in step 402, is to set the current decoder buffer—to which the data will be decoded—to the first buffer on a list of frame buffers. In the next step 403, the procedure awaits for a bottom vertical synchronization signal in the input video signal. When the controller detects such signal, the procedure moves to step 404, where a check is made, whether the buffer, next in relation to the current buffer of the decoder, is being displayed. This prevents the overwriting of the data composing the currently displayed video frame. If it is not displayed, the current decoder buffer, to which the data will be written, is set in step 405 to the next buffer and the procedure moves to step 406. In the opposite case, when the next buffer is being displayed, there is a direct shift to step 406, where—after detecting the signal of the top vertical synchronization in the analogue input signal data—decoding to the current decoder buffer the takes place. Finally the procedure proceeds to step 403 and further operates in a loop. The procedure of displaying video signal frames is shown in FIG. 5. The procedure starts in step 501. The next step 502 sets the first frame buffer chosen from the frame buffers list, as a buffer to be displayed. Next, in step 503 the system awaits for the bottom vertical synchronization on the analogue output of the video signal. When such signal is detected, the procedure moves to step 504, where the current displayed buffer is set to the previous buffer in relation to the current decoder buffer. The last step 505 is the display of content of the currently set display buffer. This display can take place after a signal of a top vertical synchronization is detected in the analogue output signal. After that, the procedure returns to step 503. From this moment on, the displaying controller operates in a loop. Frame buffers—with cyclically recorded data—are shown in FIG. 6. They are organized as a two-way list, where each buffer 602 contains, in addition to the given video frame, a pointer 603 to the next buffer in the two-way list, and a pointer 601 to the previous buffer from the two-way list. As shown in the drawing, there is also a connection between the first buffer and the last buffer in the two-way list. FIG. 7 shows signal processing when the frequency of the input signal 701 is higher than the frequency of the output signal 704. FIG. 7 also presents the current values of the decoder buffer pointer 702 and the display buffer pointer 703 during the input signal processing. At the beginning of processing of the input signal the frame F1 is being read. The display buffer pointer is set to the B1 buffer, in which there are no data. The B1 buffer is the previous buffer to the B2, which is the current decoder buffer. The time of displaying data from the B1 buffer if predefined and depends on the output signal frequency. After storing the F1 frame in the B2 buffer the next frame F2 is fetched into B3 buffer, which is now the current decoder buffer. After the B1 buffer is displayed, the F1 frame is displayed from the B2 buffer, which is chosen because it is the previous buffer in relation to the current decoder buffer B3. After storing the F6 frame in the B1 buffer, storing of the frame F7 in the B2 buffer takes place. The B2 buffer becomes the current decoder buffer and the B1 buffer becomes the current display buffer since it is the previous buffer in relation to the decoder buffer. Due to this fact the B3 buffer is omitted. The omission of the frame, the B3 buffer containing the F5 frame, or frames will occur when while displaying data of the current display buffer, the B2 buffer containing the F4 frame, the system will decode more than one frame into the remaining buffers, F5 and F6 frames. In such case the next displayed frame will be the F6 frame, which is the most recently decoded one. FIG. 8 shows signal processing when the frequency of the input signal 801 is lower than the frequency of the output signal 804. The drawing also presents the current values of the decoder buffer pointer 802 and the display buffer pointer 803 during the input signal processing. The method of choosing current decoder and display buffers was presented in FIG. 4 and FIG. 5. FIG. 8 illustrates how certain frames will be displayed more than once when the output frames frequency is higher than the input frequency. The first frame that will be displayed twice is the F2 frame from the B3 buffer. This will happen because when the F2 frame is being displayed for the first time there is no new frame to be displayed i.e. the new frame is still being decoded to the B1 buffer. The preferred embodiment having been thus described, it will now be evident to those skilled in the art that further variation thereto may be contemplated. Such variations are not regarded as a departure from the invention, the true scope of the invention being set forth in the claims appended hereto.

<SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The present invention relates to a device for control of display of video frames and a method for control of display of video frames, used in digital decoders/receivers of television signal, in which the signal is received in an analogue form, and then, after conversion into a digital signal, it is processed in the decoder/receiver (e.g. OSD ‘On-Screen Display’ functions are applied). Next it is converted to an analogue format, which is transmitted to a receiver, for example a TV set. 2. Brief Description of the Background of the Invention Including Prior Art The methods of controlling display of video signal frames, known from the prior art, can be divided into three groups. The first group uses a single frame buffer, and the input of video signal (refresh frequency timer) is not synchronized with the output. The drawback of this solution are the interferences, which appear during the displaying of video frames. They appear, for instance, as a shift of the top part of the picture in relation to the bottom part. The second solution consists in applying a single frame buffer and synchronization of the input signal timers with the output signal. Although interferences occurring in the first method do not appear here, it is still necessary to synchronize the timers. Moreover, there appear problems related to switching among input signals with different synchronization frequencies/phases. The third method, called “back buffering” or “double buffering”, requires two frame buffers. Data are fetched into the first one, and next they are copied to the second one. The contents of the second buffer are displayed. A disadvantage of this solution is the necessity of copying large amounts of data. The U.S. Pat. No. 5,446,496 presents a solution, in which the frequency of video frames is converted. The output frequency in this solution must be lower than the input frequency. Moreover, a single frame buffer is used for the conversion, which—during considerable discrepancies between input and output frame frequencies—may lead to the loss of many video signal frames. This is due to the fact, that the currently displayed data cannot be overwritten.

<SOH> SUMMARY OF THE INVENTION <EOH>Purposes of the Invention It is the object of this invention to eliminate the interferences and allowing a conversion of video frames frequency, in such a way, that the output frequency can be either lower or higher than the input frequency. This and other objects and advantages of the present invention will become apparent from the detailed description, which follows.

20040927

20071218

20050407

67870.0

KOSTAK, VICTOR R

RECEIVER OF ANALOGUE VIDEO SIGNAL HAVING MEANS FOR ANALOGUE VIDEO SIGNAL CONVERSION AND METHOD FOR CONTROL OF DISPLAY OF VIDEO FRAMES

UNDISCOUNTED

ACCEPTED

ACCEPTED

APPARATUS AND METHODS FOR REDUCING STAND-OFF EFFECTS OF A DOWNHOLE TOOL

A method for reducing stand-off effects of a downhole tool includes disposing the downhole tool in a borehole, wherein the downhole tool comprises at least one moveable section disposed between an energy source and a receiver on the downhole tool; and activating the at least one moveable section to reduce a thickness of at least one selected from a mud layer and a mudcake between the downhole tool and a wall of the borehole. A downhole tool includes an energy source and a receiver disposed on the downhole tool; at least one moveable section disposed between the energy source and the receiver; and an activation mechanism for reducing a thickness of at least one selected from a mud layer and a mudcake between the downhole tool and a wall of a borehole.

1. A method for reducing stand-off effects of a downhole tool, comprising: disposing the downhole tool in a borehole, wherein the downhole tool comprises at least one moveable section disposed between an energy source and a receiver on the downhole tool; and activating the at least one moveable section to reduce a thickness of at least one selected from a mud layer and a mudcake between the downhole tool and a wall of the borehole. 2. The method of claim 1, wherein the downhole tool is one selected from a wireline tool, a logging-while-drilling too, a measurement-while-drilling tool, and a measurement-while-tripping tool. 3. The method of claim 1, wherein the downhole tool is an electromagnetic logging tool or a gamma-ray density tool. 4. The method of claim 1, wherein the activating is by a mechanical mechanism or a hydraulic mechanism. 5. The method of claim 1, wherein the at least one moveable section is attached to the downhole tool by a hinge. 6. A downhole tool, comprising: an energy source and a receiver disposed on the downhole tool; at least one moveable section disposed between the energy source and the receiver; and an activation mechanism for reducing a thickness of at least one selected from a mud layer and a mudcake between the downhole tool and a wall of a borehole. 7. The downhole tool of claim 6, wherein the downhole tool is one selected from a wireline tool, a logging-while-drilling too, a measurement-while-drilling tool, and a measurement-while-tripping tool. 8. The downhole tool of claim 6, wherein the downhole tool is an electromagnetic logging tool or a gamma-ray density tool. 9. The downhole tool of claim 6, wherein the activation mechanism is a mechanical mechanism or a hydraulic mechanism. 10. The downhole tool of claim 6, wherein the at least one moveable section is attached to the downhole tool by a hinge. 11. The downhole tool of claim 6, wherein the energy source and the receiver are disposed on a non-moveable part on the downhole tool.

CROSS-REFERENCE TO RELATED APPLICATIONS Not applicable. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT Not applicable. BACKGROUND OF INVENTION 1. Field of the Invention The invention relates generally to tools for well logging. More particularly, the invention relates to devices and methods for reducing stand-off effects in downhole tools. 2. Background Art Oil and gas industry uses various tools to probe the formation to locate hydrocarbon reservoirs and to determine the types and quantities of hydrocarbons. A typical logging tool transmits energy (a signal) from a source (e.g., a transmitter of a propagation tool or a gamma-ray source of a density logging tool) into the borehole and the formation. The transmitted signal interacts with matters in the formation when it traverses the formation. As a result of these interactions, the properties of the transmitted signal is altered, and some of the altered signals may return to the borehole and the tool. One or more sensors (e.g., receivers) may be disposed on the tool to detect the returned signals. The detected signals can then be analyzed to provide insights into the formation properties. Ideally, the receivers detect only the signals returned from the formation. However, if the transmitters and the receivers do not directly contact the formation (i.e., tool stand-off), the borehole and the borehole fluid often provide an alternate transmission pathway for the signals to travel from the transmitters to the receivers. Signal transmitted in the borehole may be generally referred to as “trapped signals,” which complicate the measurements and may render the analysis of the desired signals difficult or impossible. Various approaches are known in the art for reducing or eliminating tool stand-off effects (or borehole effects). The following description uses electromagnetic propagation tools as examples to illustrate the problems associated with tool stand-off effects and to illustrate methods for overcoming these effects. One of ordinary skill in the art would appreciate that embodiments of the invention may be used with various tools and are not limited to these specific examples. Electromagnetic (EM) propagation tools are commonly used to measure the subsurface properties of resistivity and/or dielectric constant. For discussion of EM propagation measurements see: “Theory of Microwave Dielectric Logging Using the Electromagnetic Wave Propagation Method,” Freeman et al., Geophysics, 1979; U.S. Pat. Nos. 4,689,572 and 4,704,581 issued to Clark. EM propagation can also be used to provide borehole imaging while drilling. The boreholes may be drilled with an oil-based mud (OBM) or an water-based mud (WBM). In a typical EM propagation tool, the antennas are mounted on one or more articulated pads. FIGS. 1A-1C show a schematic of a typical EM tool having antennas or magnetic dipole arrays mounted on a pad. FIG. 1A shows a top view of the pad, which typically has dimensions of 20 cm by 8 cm and a thickness of 3 cm. As shown in FIG. 1A, two transmitters T1 and T2 are each disposed on one side of the two receivers R1 and R2 at equal spacings. The two transmitters T1 and T2 can be sequentially fired to provide compensated measurements, as disclosed in U.S. Pat. No. 3,849,721 issued to Calvert. FIG. 1B shows a side view of the pad, while FIG. 1C shows a cross sectional view of the pad, illustrating the curved pad face that is designed to fit the borehole wall. The curvatures of the pads may be designed to fit a particular borehole diameter (e.g., 6, 8½, or 12½ inches). FIG. 1C also shows that the pad face may be coated with a hardfacing material to make the pad more wear resistant. The antennas (as shown in FIG. 1A) may be endfire and/or broadside magnetic dipole arrays, which may be operated at a proper frequency (e.g., approximately 1 GHZ for propagation measurements). Other electromagnetic sensors have been proposed for high frequency measurements, for example, using button electrodes that function as normal electric dipoles (being normal to the pad face), crossed magnetic dipoles, and normal magnetic dipoles. Because stand-off between the sensors and the formation can lead to erroneous measurements, especially in oil based mud, the pads that house the sensors should be articulated to maintain contact with the formation at all times. Ideally, the distance between the pad face and the borehole wall should be 0.1 inches or less. With the antennas mounted in the articulated pad, cables would need to be routed to the pad (see FIG. 1C). In some tools, it may be necessary to place some front-end electronics in the pad to reduce the number of cables and/or to improve the measurement accuracy. Because the pads are subject to higher shock levels than the drill collars, pad-mounted electronics will have to be designed to survive in harsher environments. An extremely harsh environment may be encountered by the antennas and electronics mounted in the pad and the cables connecting the pad to the drill collar. For example, if the drill collar is rotating at 120 RPM in an 8.5 inch borehole, then the articulated pad will travel 16,000 ft/hr just from the tool's rotation. In a 100 hour Logging While Drilling (LWD) job, the pad will travel 1,600,000 ft. To put this in perspective, a typical wireline tool travels only a few thousand feet in a logging job. Therefore, the mechanical abuse on an LWD pad in one LWD job is roughly three orders of magnitude greater than on a wireline pad in a wireline job. Hence, abrasion of the antennas could be a significant problem leading to antenna failure and high maintenance and service costs. The minimum reliability for an LWD tool should be 2000 hr, which implies that the pad-mounted antennas need to survive 32,000,000 ft before failures occur. Mechanical shock for components mounted in an articulated pad is another serious concern. Assuming 120 RPM and one shock per revolution, the pad will experience 7,2000 shocks/hr. In a 100 hr job, the pad would experience 720,000 shocks. To achieve an MTBF of 2000 hr, the pad components would then have to survive 14,4000,000 shocks. These numbers are well above the number of shocks currently experienced by Measurement While Drilling (MWD) or LWD components which are not mounted in an articulated pad. Furthermore, since the pad is small, lightweight, and articulated, the shock level will be considerably higher in the pad than in the drill collar. Developing antennas and electronics to survive these shock levels is challenging. Frictional contact between the pad and the formation may also result in the pad being subjected to much higher temperatures than the ambient downhole temperature. Another concern is the repeated stress applied to the cables between the pad and the drill collar. Again assuming 120 RPM, the cables will be twisted 14,400 times per hr (opening and closing the pad every revolution) and 1,440,000 times in a 100 hr LWD job. The above description shows that while mounting the sensors on articulate pads can overcome most of the adverse effects associated with tool stand-offs, this approach subjects the sensors and the electronics to harsher environments. An alternative is to mount the sensors in non-moving parts of a drill string assembly. For example, U.S. Pat. No. 6,173,793 B1 issued to Thompson et al. discloses tools having sensors mounted in non-rotating pads. While this approach overcomes some problems associated with rotating pads, it is sometimes desirable to have sensors rotate with the drill strings, for example to provide full-bore images. Therefore, there still exists a need for methods that can provide similar benefits of articulating pads without subjecting the sensors to the extremely harsh environment experienced by a typical articulating pad. SUMMARY OF INVENTION One aspect of the invention relates to methods for reducing stand-off effects of a downhole tool. A method in accordance with one embodiment of the invention includes disposing the downhole tool in a borehole, wherein the downhole tool comprises at least one moveable section disposed between an energy source and a receiver on the downhole tool; and activating the at least one moveable section to reduce a thickness of a mud layer and/or mudcake between the downhole tool and a wall of the borehole. Here, mud refers to the specialized drilling fluid used to lubricate the drill string, used to lift rock cuttings to surface, and used to prevent blowouts. Mudcake refers to a generally soft and thin layer that forms on the surface of the borehole in permeable rock formations. As the boundary between the mud and mudcake can be indistinguishable, hereafter the mud layer and any mudcake will simply be referred to as the “mud layer.” One aspect of the invention relates to downhole tools. A downhole tool in accordance with one embodiment of the invention includes an energy source and a receiver disposed on the downhole tool; at least one moveable section disposed between the energy source and the receiver; and an activation mechanism for reducing a thickness of a mud layer between the downhole tool and a wall of a borehole. Other aspects and advantages of the invention will be apparent from the following description and the appended claims. BRIEF DESCRIPTION OF DRAWINGS FIG. 1A shows a top view of a prior art electromagnetic dipole arrays disposed on a articulating pad. FIG. 1B shows a side view of the articulating pad of FIG. 1A. FIG. 1C shows a cross sectional view of the articulating pad of FIG. 1A. FIG. 2 shows energy transmission pathways via the formation and the borehole of a conventional electromagnetic logging tool disposed in a borehole. FIG. 3 shows energy transmission pathway via the formation of an electromagnetic logging tool disposed in a borehole in accordance with one embodiment of the invention. FIG. 4 shows a logging tool having moveable sections in a closed position in accordance with one embodiment of the invention. FIG. 5 shows a logging tool having moveable sections in an open (deployed) position in accordance with one embodiment of the invention. FIG. 6 shows energy transmission pathways via the formation and the borehole of a conventional gamma-ray density logging tool disposed in a borehole. FIG. 7 shows energy transmission pathway via the formation of a gamma-ray density logging tool disposed in a borehole in accordance with one embodiment of the invention. DETAILED DESCRIPTION Embodiments of the invention relate to methods for reducing stand-off effects without mounting sensors (e.g., antennas) on articulated pads. In accordance with embodiments of the invention, the sensors or antennas (e.g., transmitters and receivers) may be mounted on the drill collars or stabilizers of a tool, and one or more articulating (deployable) pads are placed between the energy source (e.g., transmitters) and detectors (e.g., receivers). These pads may be articulated to eliminate or minimize the mud layer between the pads and the formation, and, therefore, to eliminate or minimize the transmission of the trapped signals. Embodiments of the invention is based on the concept of divorcing the sensors (e.g., antennas) from the articulated pad, while retaining the advantages of articulation. Embodiments of the invention may be applied to any sensor or tool that is adversely impacted by trapped signals traveling in a mud layer between a source and a receiver. Such sensors or tools may include, for example, EM propagation tools and electrode tools. For example, embodiments of the invention can also be applied to nuclear measurements such as formation density measurements, in which gamma-rays are emitted from a radioactive source (e.g. 137Cs) and detected by a scintillation counter disposed at a distance from the source. To illustrate the working principles of embodiments of the invention, FIG. 2 shows an EM propagation tool 21 having two transmitters T1, T2 and two receivers R1, R2 (similar to that shown in FIG. 1). The transmitters T1, T2 and receivers R1, R2 could be broadside, endfire, crossed, or normal magnetic dipole arrays, or normal electric dipoles. The tool 21 in FIG. 2 is a borehole compensated system, in which two transmitters T1, T2 are each disposed on one side of the two receivers R1, R2 at equal distances. The two transmitters T1, T2 may be sequentially fired to provide two sets of measurements (attenuation and phase shift between the receivers R1, R2) that may be used to cancel most of the differences in the sensitivities of the two receiving antennas. As shown in FIG. 2, when transmitter T1 is activated, it may excite two distinct propagating waves 24,25 that reach the receivers R1,R2. The “lateral wave” 24 can be viewed as traveling through the formation 23 to reach the receivers R1,R2, while the “trapped wave” 25 can be viewed as traveling in the mud layer 22 between the tool face 26 and the formation 23. If it were possible to measure only the lateral wave 24, then the phase shift (φ) and attenuation (A) measured between the two receivers R1,R2 would accurately describe the formation properties. However, the receivers R1,R2 would detect both the lateral 24 and trapped waves 25, and, therefore, the measurements obtained in a typical logging operation can be significantly influenced by the trapped waves 25. The trapped wave's characteristics are largely affected by the mud layer's properties. The stronger the trapped wave, the more difficult it is to determine the formation properties. In general, the trapped wave has a greater impact on the measurements of a propagation tool when: (1) the stand-off occurs in very resistive mud (e.g., oil-based mud), (2) the formation is very conductive compared to the mud, and (3) and the stand-off is significant (e.g., greater than approximately 0.1 to 0.2 inches). In the prior art, the impact of trapped waves is typically minimized by mounting sensors in articulated pads, which, when deployed, eliminate or reduce stand-offs in front of the sensors. By eliminating or reducing the stand off, the source on the articulated pad injects energy directly into the formation, minimizing the generation of the trapped waves. However, this approach subjects the sensors and their associated electronics and the cables to stress and wear. Embodiments of the invention use an alternative approach that divorces the sensors from the articulating pads. Instead, embodiments of the invention use moveable sections between the transmitters (or other energy sources) and receivers to fill the gap between the tool surface and the formation, as shown in FIG. 3. FIG. 3 shows a logging tool 31, in accordance with one embodiment of the invention, having two transmitters T1,T2 and two receivers R1,R2 disposed on the non-moveable parts (e.g., collar or stabilizers) of the tool, instead of articulating pads (see FIG. 1). As shown in FIG. 3, two moveable (deployable) sections 37,38 are disposed between the transmitters T1,T2 and receivers R1,R2. When deployed, these moveable sections 37,38 essentially cut off the pathways that may conduct the trapped waves (shown as 25 in FIG. 2). The moveable sections 37,38 are preferably made of wear resistant materials (e.g., metal) and may be further protected with a hardfacing coating (e.g., PDC coating or cubic boron nitride coating). In the tool shown in FIG. 3, the transmitters T1,T2 and receivers R1,R2 themselves are rigidly mounted on non-moveable sections on the tool 31 (e.g., the drill collar or stabilizer). Therefore, the transmitters T1,T2 and the receivers R1,R2 would not experience the same level of environmental shocks, mechanical flexing, and abrasion as they would, if mounted on an articulated pad. In addition, the electronics (not shown) are located inside the drill collar, and the antennas may be connected to the electronics without exposing wires (not shown) to borehole pressure and mud. The moveable sections 37,38 may be simple metallic parts (e.g. steel with hardfacing or TCI inserts), which can be replaced as wear items. This can significantly reduce the costs associated with the maintenance and services of the tools. The moveable sections 37,38 may be activated by any mechanism known in the art, e.g., springs or hydraulic pressure differential between the inside and outside of the drill collar. The stand-off with an LWD tool that has sensors mounted on a stabilizer typically is relatively small (e.g., about 2 inch or 1.3 cm), and, therefore, moveable sections do not have to travel a great distance. For example, in some embodiments, the transmitters and receivers may be mounted on an upset on the drill collar OD, or in a stabilizer blade. As the drill collar rotates, the distance between the antennas and the formation will vary from zero stand-off (e.g., when the antennas are on the low side of a deviated borehole) to a maximum stand-off (approximately 2 inch, when they are on the high side of the borehole). Hence, in most cases, the moveable sections need only be able to move in and out a fraction of an inch (2.5 cm). The moveable sections may use any mechanism known in the art for attachment and deployment, including hinges and springs, hydraulics, etc. For example, in FIG. 3, springs 39 are used to articulate (deploy) the moveable sections 37,38. Furthermore, FIG. 4 and FIG. 5 show examples, in which hinges are used to attach and control the movement of moveable sections. The hinge option may be similar to those used in the PowerDrive™ pads from Schlumberger Technology Corp. (Houston, Tex.). FIG. 4 shows the moveable sections 47,48 in the closed position, while FIG. 5 shows the moveable sections 57,58 in the open position. These figures illustrate that the antennas T1,T2 and R1,R2 are rigidly mounted on stabilizer blades, while the moveable sections are attached to the drill collar with hinges. The hinges are attached in a manner such that the hinge is the leading edge during normal rotation. These moveable sections may be activated (deployed) by a pressure differential across the inside and outside of the drill collar when the mud pumps are on, and when the mud pumps are off, these sections may be retracted by bias springs. In this case, the default position of the moveable sections is the closed position. In alternative embodiments, these moveable sections (pads) may be constructed to have a slight bias pressure (e.g., using springs) to have them in the activated (deployed) state by default, and the extent of the movement (extension) is limited by the borehole diameter when they are in the borehole. Some embodiments of the invention may use other mechanical options to open and close the moveable sections. For example, radial expansion may use spring or hydraulics activation. In these embodiments, bolts or lips may be used to prevent the sections from becoming detached from the drill collar. One of ordinary skill in the art would appreciate that other variations are possible without departing from the scope of the invention. The above description uses an electromagnetic logging tool to illustrate embodiments of the invention. As noted above, embodiments of the invention may be used in other situations where signal propagation in the borehole produces undesirable effects. These situations include many other formation logging tools, such as the gamma-ray density logging tools. For a description of gamma-ray density logging tools see U.S. Pat. No. 3,263,083 issued to Johnson et al., U.S. Pat. No. 3,858,037 issued to Moore et al., and U.S. Pat. No. 3,864,569 issued to Tittman. FIG. 6 shows an embodiment of the invention used in a gamma-ray density logging tool 61 that uses a radioactive source 62 (e.g. 137Cs) to provide a stream of gamma-rays. These gamma-rays are ultimately detected by “near” 63 and “far” 64 detectors, as indicated by the solid lines, curve 65,66, in FIG. 6. The detectors 63,64 are typically sodium-iodine crystals with photomultipliers. Gamma-rays enter the formation and are Compton scattered and attenuated by electrons. The greater the electron density is, the more scattering and attenuation occur. The electron density is related to the formation's mass density, with typical formation mass densities being 2 to 3 gm/cc. On the other hand, drilling mud has a mass density typically 1 to 2 gm/cc, and, therefore, it does not attenuate gamma-rays as efficiently. If stand-off occurs, then gamma-rays can stream through the mud layer and reach the detectors with little attenuation. The dashed lines, curve 67, in FIG. 6 illustrate gamma-rays traveling through the mud layer. The gamma rays traveling in the mud layer can seriously degrade the formation density measurements. Therefore, in the prior art wireline density logging tools, the density measurement source and/or detectors are typically disposed on articulated pads to ensure good contact with the borehole wall, and to minimize any stand-off effects. However, an articulated pad containing a radioactive source and detectors would be extremely difficult to build and possibly quite dangerous for LWD. The possibility of losing a radioactive source downhole precludes mounting it on an articulated pad, which can be destroyed or become detached from the drill collar. Also, the radioactive source and the detectors are quite large and would be difficult to fit into a typical articulated pad. Thus, existing LWD density tools typically place the source and detectors inside the drill collar or inside a fixed stabilizer blade. As the LWD density tool rotates, the stand-off between the tool and borehole wall varies from zero to about ½ inch or more, depending on the stabilizer OD and the borehole diameter. If the stand-off is greater than about ¾ inch, the density measurements may be very seriously impaired. For example, density images covering the entire borehole would not be possible with large stand-offs on the top of the hole. Adding a moveable section to the density measurement can block the gamma-rays traveling in the stand-off region. This is illustrated in FIG. 7. The moveable section 77 shown in FIG. 7 is preferably made of a high-density material, such as steel, which has a density of 7.8 μm/cc. This will fully attenuate any gamma-rays traveling through the mud layer. The radioactive source 72 and gamma-ray detectors 73,74 can remain mounted in the drill collar or under a fixed stabilizer blade as before. The moveable sections 77 may be attached and deployed using any mechanism described above. For example, a hinged system as described in FIGS. 4 and 5 may be used. Because there is only one source 72, a moveable section disposed between the source 72 and the detectors 73,74 will be sufficient. The above description uses an EM tool and a density logging tool to illustrate embodiments of the invention. However, embodiments of the invention are not so limited and can be applied to any tool that suffers from adverse effects arising from trapped signals traveling in the borehole. Furthermore, embodiments of the invention may be used on wireline, logging-while-drilling (LWD), measurement-while-drilling (MWD), or measurement-while-tripping (MWT) tools. One of ordinary skill in the art would appreciate that embodiments of the invention benefits from having moveable sections disposed between energy sources and receivers on the tool. However, embodiments of the invention do not exclude tools that also have the sensors disposed on articulating pads. Therefore, these tools are within the scope of the invention. Advantages of the invention may include one or more of the following. Embodiments of the invention are based on a concept that divorces the sensors from the articulating pads, while retaining the benefits of an articulating pads. The sensors are disposed on fixed parts of the tool, while one or more articulating pads or sections are disposed between the energy source and the receivers to prevent or reduce the trapped signal transmission in the mud layer. The sensors of these embodiments are not subjected to the same extent of mechanical adverse impacts as compared to those disposed on articulating pads. The moveable sections of embodiments of the invention can effectively reduce or prevent signals from traveling in the borehole. These moveable sections are relatively inexpensive to manufacture and to replace. Therefore, the overall costs of the manufacturing and maintenance of the tools can be significantly reduced. Embodiments of the invention have broad applicability and can be used on a wide range of downhole tools. While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.

<SOH> BACKGROUND OF INVENTION <EOH>1. Field of the Invention The invention relates generally to tools for well logging. More particularly, the invention relates to devices and methods for reducing stand-off effects in downhole tools. 2. Background Art Oil and gas industry uses various tools to probe the formation to locate hydrocarbon reservoirs and to determine the types and quantities of hydrocarbons. A typical logging tool transmits energy (a signal) from a source (e.g., a transmitter of a propagation tool or a gamma-ray source of a density logging tool) into the borehole and the formation. The transmitted signal interacts with matters in the formation when it traverses the formation. As a result of these interactions, the properties of the transmitted signal is altered, and some of the altered signals may return to the borehole and the tool. One or more sensors (e.g., receivers) may be disposed on the tool to detect the returned signals. The detected signals can then be analyzed to provide insights into the formation properties. Ideally, the receivers detect only the signals returned from the formation. However, if the transmitters and the receivers do not directly contact the formation (i.e., tool stand-off), the borehole and the borehole fluid often provide an alternate transmission pathway for the signals to travel from the transmitters to the receivers. Signal transmitted in the borehole may be generally referred to as “trapped signals,” which complicate the measurements and may render the analysis of the desired signals difficult or impossible. Various approaches are known in the art for reducing or eliminating tool stand-off effects (or borehole effects). The following description uses electromagnetic propagation tools as examples to illustrate the problems associated with tool stand-off effects and to illustrate methods for overcoming these effects. One of ordinary skill in the art would appreciate that embodiments of the invention may be used with various tools and are not limited to these specific examples. Electromagnetic (EM) propagation tools are commonly used to measure the subsurface properties of resistivity and/or dielectric constant. For discussion of EM propagation measurements see: “Theory of Microwave Dielectric Logging Using the Electromagnetic Wave Propagation Method,” Freeman et al., Geophysics, 1979; U.S. Pat. Nos. 4,689,572 and 4,704,581 issued to Clark. EM propagation can also be used to provide borehole imaging while drilling. The boreholes may be drilled with an oil-based mud (OBM) or an water-based mud (WBM). In a typical EM propagation tool, the antennas are mounted on one or more articulated pads. FIGS. 1A-1C show a schematic of a typical EM tool having antennas or magnetic dipole arrays mounted on a pad. FIG. 1A shows a top view of the pad, which typically has dimensions of 20 cm by 8 cm and a thickness of 3 cm. As shown in FIG. 1A , two transmitters T 1 and T 2 are each disposed on one side of the two receivers R 1 and R 2 at equal spacings. The two transmitters T 1 and T 2 can be sequentially fired to provide compensated measurements, as disclosed in U.S. Pat. No. 3,849,721 issued to Calvert. FIG. 1B shows a side view of the pad, while FIG. 1C shows a cross sectional view of the pad, illustrating the curved pad face that is designed to fit the borehole wall. The curvatures of the pads may be designed to fit a particular borehole diameter (e.g., 6, 8½, or 12½ inches). FIG. 1C also shows that the pad face may be coated with a hardfacing material to make the pad more wear resistant. The antennas (as shown in FIG. 1A ) may be endfire and/or broadside magnetic dipole arrays, which may be operated at a proper frequency (e.g., approximately 1 GHZ for propagation measurements). Other electromagnetic sensors have been proposed for high frequency measurements, for example, using button electrodes that function as normal electric dipoles (being normal to the pad face), crossed magnetic dipoles, and normal magnetic dipoles. Because stand-off between the sensors and the formation can lead to erroneous measurements, especially in oil based mud, the pads that house the sensors should be articulated to maintain contact with the formation at all times. Ideally, the distance between the pad face and the borehole wall should be 0.1 inches or less. With the antennas mounted in the articulated pad, cables would need to be routed to the pad (see FIG. 1C ). In some tools, it may be necessary to place some front-end electronics in the pad to reduce the number of cables and/or to improve the measurement accuracy. Because the pads are subject to higher shock levels than the drill collars, pad-mounted electronics will have to be designed to survive in harsher environments. An extremely harsh environment may be encountered by the antennas and electronics mounted in the pad and the cables connecting the pad to the drill collar. For example, if the drill collar is rotating at 120 RPM in an 8.5 inch borehole, then the articulated pad will travel 16,000 ft/hr just from the tool's rotation. In a 100 hour Logging While Drilling (LWD) job, the pad will travel 1,600,000 ft. To put this in perspective, a typical wireline tool travels only a few thousand feet in a logging job. Therefore, the mechanical abuse on an LWD pad in one LWD job is roughly three orders of magnitude greater than on a wireline pad in a wireline job. Hence, abrasion of the antennas could be a significant problem leading to antenna failure and high maintenance and service costs. The minimum reliability for an LWD tool should be 2000 hr, which implies that the pad-mounted antennas need to survive 32,000,000 ft before failures occur. Mechanical shock for components mounted in an articulated pad is another serious concern. Assuming 120 RPM and one shock per revolution, the pad will experience 7 , 2000 shocks/hr. In a 100 hr job, the pad would experience 720,000 shocks. To achieve an MTBF of 2000 hr, the pad components would then have to survive 14,4000,000 shocks. These numbers are well above the number of shocks currently experienced by Measurement While Drilling (MWD) or LWD components which are not mounted in an articulated pad. Furthermore, since the pad is small, lightweight, and articulated, the shock level will be considerably higher in the pad than in the drill collar. Developing antennas and electronics to survive these shock levels is challenging. Frictional contact between the pad and the formation may also result in the pad being subjected to much higher temperatures than the ambient downhole temperature. Another concern is the repeated stress applied to the cables between the pad and the drill collar. Again assuming 120 RPM, the cables will be twisted 14,400 times per hr (opening and closing the pad every revolution) and 1,440,000 times in a 100 hr LWD job. The above description shows that while mounting the sensors on articulate pads can overcome most of the adverse effects associated with tool stand-offs, this approach subjects the sensors and the electronics to harsher environments. An alternative is to mount the sensors in non-moving parts of a drill string assembly. For example, U.S. Pat. No. 6,173,793 B1 issued to Thompson et al. discloses tools having sensors mounted in non-rotating pads. While this approach overcomes some problems associated with rotating pads, it is sometimes desirable to have sensors rotate with the drill strings, for example to provide full-bore images. Therefore, there still exists a need for methods that can provide similar benefits of articulating pads without subjecting the sensors to the extremely harsh environment experienced by a typical articulating pad.

<SOH> SUMMARY OF INVENTION <EOH>One aspect of the invention relates to methods for reducing stand-off effects of a downhole tool. A method in accordance with one embodiment of the invention includes disposing the downhole tool in a borehole, wherein the downhole tool comprises at least one moveable section disposed between an energy source and a receiver on the downhole tool; and activating the at least one moveable section to reduce a thickness of a mud layer and/or mudcake between the downhole tool and a wall of the borehole. Here, mud refers to the specialized drilling fluid used to lubricate the drill string, used to lift rock cuttings to surface, and used to prevent blowouts. Mudcake refers to a generally soft and thin layer that forms on the surface of the borehole in permeable rock formations. As the boundary between the mud and mudcake can be indistinguishable, hereafter the mud layer and any mudcake will simply be referred to as the “mud layer.” One aspect of the invention relates to downhole tools. A downhole tool in accordance with one embodiment of the invention includes an energy source and a receiver disposed on the downhole tool; at least one moveable section disposed between the energy source and the receiver; and an activation mechanism for reducing a thickness of a mud layer between the downhole tool and a wall of a borehole. Other aspects and advantages of the invention will be apparent from the following description and the appended claims.

20040928

20071023

20060330

98919.0

E21B4700

ANDREWS, DAVID L

APPARATUS AND METHODS FOR REDUCING STAND-OFF EFFECTS OF A DOWNHOLE TOOL

UNDISCOUNTED

ACCEPTED

E21B

ACCEPTED

METHOD FOR FABRICATING DOPED POLYSILICON LINES

A method of fabricating polysilicon lines and polysilicon gates, the method of including: providing a substrate; forming a dielectric layer on a top surface of the substrate; forming a polysilicon layer on a top surface of the dielectric layer; implanting the polysilicon layer with N-dopant species, the N-dopant species about contained within the polysilicon layer; implanting the polysilicon layer with a nitrogen containing species, the nitrogen containing species essentially contained within the polysilicon layer.

1. A method of fabricating a semiconductor structure, comprising: providing a substrate; forming a dielectric layer on a top surface of said substrate; forming a polysilicon layer on a top surface of said dielectric layer; implanting said polysilicon layer with N-dopant species, said N-dopant species about contained within said polysilicon layer; implanting said polysilicon layer with a nitrogen containing species, said nitrogen containing species about contained within said polysilicon layer. 2. The method of claim 1, wherein a peak concentration of said N-dopant species is about equal to a peak concentration of said nitrogen containing species at about a same distance from a top surface of said polysilicon layer. 3. The method of claim 1, wherein a surface concentration of said N-dopant species is about equal to a surface concentration of said nitrogen containing species at about a same distance from a top surface of said polysilicon layer. 4. The method of claim 1, wherein said N-dopant species and said nitrogen containing species have about a same ion implantation concentration profile. 5. The method of claim 1, wherein a surface concentration of said N-dopant species is between about 1E18 atm/cm3 to about 1E22 atm/cm3 and a surface concentration of said nitrogen containing species is between about abut 1E18 atm/cm3 to about 1E21 atm/cm3. 6. The method of claim 1, wherein: wherein a peak concentration of said N-dopant species is between about 1E18 atm/cm3 to about 1E22 atm/cm3 and a peak concentration of said nitrogen containing species is between about 1E18 atm/cm3 to about 1E21 atm/cm3; and said peak concentration of said N-dopant species occurring between a distance of about 0 nm and about ⅓ of a thickness of said polysilicon layer from a top surface of said polysilicon layer and said peak concentration of said nitrogen containing species occurring between about 0 nm to about ⅔ of said thickness of said polysilicon layer from said top surface of said polysilicon layer. 7. The method of claim 1, wherein: said N-dopant species is selected from the group consisting of phosphorus and arsenic; and said nitrogen containing species is selected from the group consisting of N, N2, NO, NF3, N2O and NH3. 8. The method of claim 1, further including: patterning said polysilicon layer into one or more polysilicon lines; performing a thermal oxidation of sidewalls and top surfaces of said one or more polysilicon lines to form a thermal oxide layer, said thermal oxide layer of about uniform thickness. 9. The method of claim 8, wherein said nitrogen containing species retards oxidation of said one or more polysilicon lines. 10. A method of fabricating a semiconductor structure, comprising: (a) providing a substrate; (b) forming a dielectric layer on a top surface of said substrate; (c) forming a polysilicon layer on a top surface of said dielectric layer; (d) implanting a first portion of said polysilicon layer with N-dopant species, said N-dopant species about contained within said polysilicon layer; (e) implanting a second and different portion of said polysilicon layer with P-dopant species, said P-dopant species about contained within said polysilicon layer; (f) implanting said first portion of said polysilicon layer with a nitrogen containing species, said nitrogen containing species essentially contained within said polysilicon layer. 11. The method of claim 10, further including: (g) implanting said second portion of said polysilicon layer with said nitrogen containing species. 12. The method of claim 10, wherein a peak concentration of said N-dopant species is about equal to a peak concentration of said nitrogen containing species at about a same distance from a top surface of said polysilicon layer. 13. The method of claim 10, wherein a surface concentration of said N-dopant species is about equal to a surface concentration of said nitrogen containing species at about a same distance from a top surface of said polysilicon layer. 14. The method of claim 10, wherein said N-dopant species and said nitrogen containing species have about a same ion implantation concentration profile. 15. The method of claim 10, wherein a surface concentration of said N-dopant species is between about 1E18 atm/cm3 to about 1E22 atm/cm3 and a surface concentration of said nitrogen containing species is between about abut 1E18 atm/cm3 to about 1E21 atm/cm3. 16. The method of claim 10, wherein: wherein a peak concentration of said N-dopant species is between about 1E18 atm/cm3 to about 1E22 atm/cm3 and a peak concentration of said nitrogen containing species is between about 1E18 atm/cm3 to about 1E21 atm/cm3; and said peak concentration of said N-dopant species occurring between a distance of about 0 nm and about ⅓ of a thickness of said polysilicon layer from a top surface of said polysilicon layer and said peak concentration of said nitrogen containing species occurring between about 0 nm to about ⅔ of said thickness of said polysilicon layer from said top surface of said polysilicon layer. 17. The method of claim 10, wherein: said N-dopant species is selected from the group consisting of phosphorus and arsenic; and said nitrogen containing species is selected from the group consisting of N, N2, NO, NF3, N2O and NH3. 18. The method of claim 10, further including: after steps (a) through (f), (g) patterning said first portion of said polysilicon layer into one or more NFET gate electrodes and patterning said second portion of said polysilicon layer into one or more PFET gate electrodes; and (h) performing a thermal oxidation of sidewalls and top surfaces of said one or more NFET and PFET gate electrodes to form a thermal oxide layer. 19. The method of claim 18, wherein said nitrogen containing species retards oxidation of said one or more NFET gate electrodes. 20. The method of claim 18, further including: after step (h), removing said thermal oxide layer from said top surfaces of said NFET and PFET gate electrodes and forming a metal silicide layer on said top surfaces of NFET and PFET gate electrodes.

BACKGROUND OF INVENTION 1. Field of the Invention The present invention relates to the field of semiconductor fabrication; more specifically, it relates a method of fabricating doped polysilicon lines and complementary metal-oxide-silicon (CMOS) doped polysilicon gates. 2. Background of the Invention Advanced CMOS devices utilize doped polysilicon lines and gates with metal silicide layers as a method of improving and matching the performance of N-channel field effect transistors (NFETs) and P-channel field effect transistors (PFETs). However, controlling the width and sheet resistance of oppositely doped polysilicon lines and gates has become more important and difficult as the widths of polysilicon lines and gates have decreased. Therefore, there is a need for a method of fabricating doped polysilicon lines and gates with improved linewidth control. SUMMARY OF INVENTION A first aspect of the present invention is a method of fabricating a semiconductor structure, comprising: providing a substrate; forming a dielectric layer on a top surface of the substrate; forming a polysilicon layer on a top surface of the dielectric layer; implanting the polysilicon layer with N-dopant species, the N-dopant species essentially contained within the polysilicon layer; implanting the polysilicon layer with a nitrogen containing species, the nitrogen containing species about contained within the polysilicon layer. A second aspect of the present invention is a method of fabricating a semiconductor structure, comprising: (a) providing a substrate; (b) forming a dielectric layer on a top surface of the substrate; (c) forming a polysilicon layer on a top surface of the dielectric layer; (d) implanting a first portion of the polysilicon layer with N-dopant species, the N-dopant species about contained within the polysilicon layer; (e) implanting a second and different portion of the polysilicon layer with P-dopant species, the P-dopant species about contained within the polysilicon layer; (f) implanting the first portion of the polysilicon layer with a nitrogen containing species, the nitrogen containing species essentially contained within the polysilicon layer. BRIEF DESCRIPTION OF DRAWINGS The features of the invention are set forth in the appended claims. The invention itself, however, will be best understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: FIGS. 1A through 1D are partial cross-sectional views illustrating initial steps for fabricating doped polysilicon lines and gates according to a first embodiment of the present invention; FIGS. 2A through 2D are partial cross-sectional views illustrating initial steps for fabricating doped polysilicon lines and gates according to a second embodiment of the present invention; FIGS. 3A through 3D are partial cross-sectional views illustrating initial steps for fabricating doped polysilicon lines and gates according to a third embodiment of the present invention; FIG. 4 is a plot of concentration of implanted species versus distance from a top surface of a doped polysilicon layer according to the present invention; FIGS. 5A and 5B are partial cross-sectional views illustrating common intermediate steps for fabricating doped polysilicon lines and gates according to the present invention; FIG. 6 is a partial cross-sectional view of a problem solved by the present invention; and FIGS. 7A through 7E are partial cross-sectional views illustrating common last steps for fabricating doped polysilicon lines and gates according to the present invention. DETAILED DESCRIPTION The present invention will be described using fabrication of doped polysilicon gates as exemplary of the fabrication process of the present invention. A doped polysilicon gate should be considered a doped polysilicon line used for a specific purpose. FIGS. 1A through 1D are partial cross-sectional views illustrating initial steps for fabricating doped polysilicon lines and gates according to a first embodiment of the present invention. In FIG. 1A, formed in a silicon substrate 100 are an N-well 105, a P-well 110 and shallow trench isolation (STI) 115. STI 115 may be formed by etching a trench into substrate 100, depositing a dielectric layer on a surface 120 of the substrate of sufficient thickness to fill the trench, and then performing a chemical-mechanical-polishing step to remove excess dielectric layer. However, formation of STI 115 is optional, and STI 115 need not be present. Formed on top surface 120 of substrate 100 is a gate dielectric layer 125. Formed on a top surface 130 of gate dielectric layer 125 is a polysilicon layer 135. In one example, gate dielectric layer 125 is thermal silicon oxide having a thickness of between about 0.8 nm to about 4 nm. In one example, polysilicon layer 135 is undoped polysilicon having a thickness of between about 40 nm to about 200 nm. In FIG. 1B, a photoresist layer 140 is formed on a top surface 145 of polysilicon layer 135. Photoresist layer 140 is then removed from over P-well 110 by one of by one of any number of photolithographic methods known in the art. Then a phosphorus ion implantation is performed. Photoresist layer 140 is of sufficient thickness to about block phosphorus ion implantation into polysilicon layer 135 over N-well 105. The ion implantation is performed to place the peak (the maximum) of the implanted phosphorus distribution concentration (in atm/cm3) proximate to top surface 145 of polysilicon layer 135. Proximate is defined herein as within about 0 nm to about a value of one fourth of the thickness of polysilicon layer 135. (See also FIG. 4, distances D1A and D1B). The ion implantation is further performed so that the concentration distribution profile of implanted phosphorus is such as to not significantly effect the overall P dopant level of P-well 110. The phosphorus ion implant concentration distribution profile is illustrated in FIG. 4 and described infra. In one example, with polysilicon layer 135 having a thickness of about 0.15 nm, phosphorus is implanted at a dose of about 5E14 atm/cm2 to about 5E16 atm/cm2 at an energy of about 30 Kev or less. Arsenic may be subsituted for phosphorus and the arsenic. In one example, with polysilicon layer 135 having a thickness of about 0.15 nm, arsenic is implanted at a dose of about 5E14 atm/cm2 to about 5E16 atm/cm2 at an energy of about 60 Kev or less. Photoresist layer 140 is then removed. In other examples, the phosphorus and arsenic doses and energies should be scaled proportionally to the thickness of polysilicon layer 135. In FIG. 1C, a photoresist layer 150 is formed on top surface 145 of polysilicon layer 135. Photoresist layer 150 is then removed from over N-well 105 by one of any number of photolithographic methods known in the art. Then a boron ion implantation is performed. Photoresist layer 150 is of sufficient thickness to about block boron ion implantation into polysilicon layer 135 over P-well 110. The ion implantation is performed to place the peak of the implanted phosphorus distribution concentration profile proximate to top surface 145 of polysilicon layer 135. The ion implantation is further performed so that the concentration distribution profile of implanted boron is such as to not significantly effect the overall N dopant level of N-well 105. Photoresist layer 150 is then removed. In FIG. 1D, a nitrogen containing species ion implantation is performed. The ion implantation is performed to place the peak of the implanted nitrogen species distribution concentration profile proximate to top surface 145 of polysilicon layer 135. The ion implantation is further performed so that the concentration of implanted nitrogen penetrating into either gate dielectric layer 125, N-well 105 and P-well 110 is not significant. The nitrogen ion implant concentration distribution profile is illustrated in FIG. 4 and described infra. In one example, with polysilicon layer 135 having a thickness of about 0.15 nm, nitrogen (as N) is implanted at a dose of about 1E14 atm/cm2 to about 4E15 atm/cm2 at an energy of about 20 Kev or less. Other suitable nitrogen species include but is not limited to N, N2, NO, NF3, N2O and NH3. In other examples, the nitrogen dose and energy should be scaled proportionally to the thickness of polysilicon layer 135.The steps illustrated in FIGS. 5A and 5B are next performed. For the first, as well as the second and third embodiments of the present invention, one intent of the phosphorus (or arsenic), boron and nitrogen containing species ion implantations is to keep a maximum amount as possible of implanted species contained within the polysilicon layer at the time of ion implantation as well as after various later heat cycles and to keep a minimum amount as possible of implanted species from penetrating through the polysilicon layer into the underlying layers or into the substrate. Thus, the ion implantations are shallow (low energy) with concentration peaks close to the surface of the polysilicon and concentration tails that fall off to very low concentrations while still within the polysilicon. Thus the implanted species is essentially contained within the polysilicon layer. Less than about 2E12 atm/cm2 of any of the ion implanted species is intended to penetrate into substrate in the case of a polysilicon line or into the gate dielectric layer or N-well or P-well in the gate of polysilicon gates. FIGS. 2A through 2D are partial cross-sectional views illustrating initial steps for fabricating doped polysilicon lines and gates according to a second embodiment of the present invention. FIG. 2A is identical to FIG. 1A. In FIG. 2B, a nitrogen containing species ion implantation is performed. The ion implantation is performed to place the peak of the implanted nitrogen species distribution concentration profile proximate to top surface 145 of polysilicon layer 135. The ion implantation is further performed so that the concentration of implanted nitrogen penetrating into either gate dielectric layer 125, N-well 105 and P-well 110 is not significant. The nitrogen ion implant concentration distribution profile is illustrated in FIG. 4 and described infra. In one example, with polysilicon layer 135 having a thickness of about 0.15 nm, nitrogen (as N) is implanted at a dose of about 1E14 atm/cm2 to about 4E14 atm/cm2 at an energy of about 20 Kev or less. Other suitable nitrogen species include but is not limited to N2, NO, NF3, N2O and NH3. In other examples, the nitrogen dose and energy should be scaled proportionally to the thickness of polysilicon layer 135. In FIG. 2C, a photoresist layer 155 is formed on top surface 145 of polysilicon layer 135. Photoresist layer 155 is then removed from over P-well 110 by one of any number of photolithographic methods known in the art. Then a phosphorus ion implantation is performed. Photoresist layer 155 is of sufficient thickness to about block phosphorus ion implantation into polysilicon layer 135 over N-well 105. The ion implantation is performed to place the peak of the implanted phosphorus distribution concentration proximate to top surface 145 of polysilicon layer 135. The ion implantation is further performed so that the concentration distribution profile of implanted phosphorus is such as to not significantly effect the overall P dopant level of P-well 110. The phosphorus ion implant concentration distribution profile is illustrated in FIG. 4 and described infra. In one example, with polysilicon layer 135 having a thickness of about 0.15 nm, phosphorus is implanted at a dose of about 5E14 atm/cm2 to about 5E16 atm/cm2 at an energy of about 30 Kev or less. Arsenic may be subsituted for phosphorus. In one example, with polysilicon layer 135 having a thickness of about 0.15 nm, arsenic is implanted at a dose of about 5E14 atm/cm2 to about 5E16 atm/cm2 at an energy of about 60 Kev or less. In other examples, the phosphorus and arsenic doses and energies should be scaled proportionally to the thickness of polysilicon layer 135.Photoresist layer 155 is then removed. In FIG. 2D, a photoresist layer 160 is formed on top surface 145 of polysilicon layer 135. Photoresist layer 160 is then removed from over N-well 105 by one of any number of photolithographic methods known in the art. Then a boron ion implantation is performed. Photoresist layer 160 is of sufficient thickness to about block boron ion implantation into polysilicon layer 135 over P-well 110. The ion implantation is performed to place the peak of the implanted phosphorus distribution concentration profile proximate to top surface 145 of polysilicon layer 135. The ion implantation is further performed so that the concentration distribution profile of implanted boron is such as to not significantly effect the overall N dopant level of N-well 105. Photoresist layer 160 is then removed. The steps illustrated in FIGS. 5A and 5B are next performed. FIGS. 3A through 3D are partial cross-sectional views illustrating initial steps for fabricating doped polysilicon lines and gates according to a third embodiment of the present invention. FIG. 3A is identical to FIG. 1A. In FIG. 3B, a photoresist layer 165 is formed on top surface 145 of polysilicon layer 135. Photoresist layer 165 is then removed from over P-well 110 by one of any number of photolithographic methods known in the art. Then a phosphorus ion implantation is performed. Photoresist layer 165 is of sufficient thickness to about block phosphorus ion implantation into polysilicon layer 135 over N-well 105. The ion implantation is performed to place the peak of the implanted phosphorus distribution concentration proximate to top surface 145 of polysilicon layer 135. The ion implantation is further performed so that the concentration distribution profile of implanted phosphorus is such as to not significantly effect the overall P dopant level of P-well 110. The phosphorus ion implant concentration distribution profile is illustrated in FIG. 4 and described infra. In one example, with polysilicon layer 135 having a thickness of about 0.15 nm, phosphorus is implanted at a dose of about 5E14 atm/cm2 to about 5E16 atm/cm2 at an energy of about 30 Kev or less. Arsenic may be subsituted for phosphorus. In one example, with polysilicon layer 135 having a thickness of about 0.15 nm, arsenic is implanted at a dose of about 5E14 atm/cm2 to about 5E16 atm/cm2 at an energy of about 60 Kev or less. In other examples, the phosphorus and arsenic doses and energies should be scaled proportionally to the thickness of polysilicon layer 135. In FIG. 3C, a nitrogen containing species ion implantation is performed. Photoresist layer 165 is of sufficient thickness to about block nitrogen species ion implantation into polysilicon layer 135 over N-well 105. The ion implantation is performed to place the peak of the implanted nitrogen species distribution concentration profile proximate to top surface 145 of polysilicon layer 135. The ion implantation is further performed so that the concentration of implanted nitrogen penetrating into either gate dielectric layer 125 and P-well 110 is not significant. The nitrogen ion implant concentration distribution profile is illustrated in FIG. 4 and described infra. In one example, nitrogen (as N) is implanted at a dose of about 1E14 atm/cm2 to about 4E15 atm/cm2 at an energy of about 20 Kev or less. In other examples, the nitrogen dose and energy should be scaled proportionally to the thickness of polysilicon layer 135. Other suitable nitrogen species include but is not limited to N2, NO, NF3, N2O and NH3. Photoresist layer 165 is then removed. In FIG. 3D, a photoresist layer 170 is formed on top surface 145 of polysilicon layer 135. Photoresist layer 170 is then removed from over N-well 105 by one of any number of photolithographic methods known in the art. Then a boron ion implantation is performed. Photoresist layer 170 is of sufficient thickness to about block boron ion implantation into polysilicon layer 135 over P-well 110. The ion implantation is performed to place the peak of the implanted phosphorus distribution concentration profile proximate to top surface 145 of polysilicon layer 135. The ion implantation is further performed so that the concentration distribution profile of implanted boron is such as to not significantly effect the overall N dopant level of N-well 105. Photoresist layer 170 is then removed. The steps illustrated in FIGS. 5A and 5B are next performed. The present invention may be practiced by (1) fully matching ion implantation concentration profiles (concentration vs. ion implanted distance) of N-dopant (i. e. phosphorus or arsenic) and nitrogen species at the same distance into the polysilicon, by (2) matching ion implantation concentration profiles of N-dopant and nitrogen species, within a predetermined concentration range, at the same distances into the polysilicon, by (3) matching, within a predetermined concentration range, the surface concentrations of N-dopant and nitrogen in the polysilicon, or by (4) by matching, within a predetermined concentration range, peak concentrations of N-dopant and nitrogen at the same distance into the polysilicon. FIG. 4 is a plot of concentration of implanted species versus distance from a top surface of a doped polysilicon layer according to the present invention. In FIG. 4, curve 175 (N-dopant) and 180 (nitrogen species) are illustrated using option (2), matching ion implantation concentration profiles of N-dopant and nitrogen species, within a predetermined concentration range, at the same distances into the polysilicon. That is, an equation defining curve 175 and an equation defining curve 180 would yield, for the same distance from the top surface of the polysilicon, a concentration of implanted species within predetermined range of concentration of each other. In a full ion implantation profiles match, option (1) curves 175 and 180 would overlay. In FIG. 4, the N-dopant (phosphorus or arsenic) ion implantation concentration distribution profile is indicated by curve 175 and the nitrogen species ion implantation concentration distribution profile is indicated by curve 180. While curve 180 is illustrated above curve 175, curve 175 could be above 180. Also curve 175 and curve 180 could cross at one or more points. The exact relationship between curves 175 and 180 is determined by the specific ion implant dose and energy or the N dopant and the specific ion implant dose and energy or the nitrogen. The surface distribution concentration C2A of curve 175 and C2B of curve 180 occur respectively at distance 0 into the polysilicon layer. In one example, C2A is between about 1E18 atm/cm3 and about 1E21 atm/cm3 and concentration C2B is about 1E18 atm/cm3 and about 1E22 atm/cm3. The ranges of values for C2A and C2B may overlap. The peak distribution concentration C3A of curve 175 and C3B of curve 180 occur respectively proximate to the surface of the polysilicon at distance D1A and D1B into the polysilicon layer. In one example, C3A is between about 1E18 atm/cm3 and about 1E22 atm/cm3 and concentration C3B is about 1E18 atm/cm3 and about 1E21 atm/cm3. The ranges of values for C3A and C3B may overlap. In one example D1A is between about 0 nm and about ⅓ the thickness of the polysilicon and depth D1B is about 0 nm to about ⅔ the thickness of the polysilicon. The ranges for values for D1A and D1B may overlap. A concentration C1 is defined in FIG. 4 for curve 175 at a distance D2A and for curve 180 at a distance D2B into the polysilicon layer. D2A is between about 10 nm and the thickness of the polysilicon and D2B is between about 50% and about 150% of D2A. Concentration C1 is a concentration at which an insignificant amount to none of the ion implanted species exists hence essentially the implanted N dopant species and implanted nitrogen containing species are contained with the polysilicon layer. An insignificant amount of implanted species is defined as an amount of implanted species, that if present, would not significantly effect chemical processes or electrical parameters of the polysilicon layer (or gate dielectric layer or P-well) in which the implanted species is present. Table I summarizes the relationship between curve 175 (N Dopant) and curve 180 (Nitrogen species). TABLE I Minimum Maximum Value Value N Dopant Surface about 1E18 atm/cm3 about 1E22 atm/cm3 Concentration (C2A) Nitrogen Species about 1E18 atm/cm3 about 1E21 atm/cm3 Surface Concentration(C2B— N Dopant Peak about 1E18 atm/cm3 about 1E22 atm/cm3 Concentration (C3A) Nitrogen Species Peak about 1E18 atm/cm3 about 1E22 atm/cm3 Concentration(C3B) N Dopant Peak Depth about 0 nm about equal to ⅓ (D1A) the polysilicon thickness Nitrogen Species Peak about 0 nm about equal to ⅔ Depth (D1B) the polysilicon thickness N Dopant and Nitrogen Not Applicable about 1E15 atm/cm3 Species Insignificant Concentration (C1) N Dopant Insignificant 10 nm about equal to the Concentration full thickness of the Depth (D2A) polysilicon Nitrogen Species about 150% of D1A about 150% of D2A Insignificant Concentration Depth (D2B) Also in FIG. 4, the gate dielectric layer occurs between a distance D3 and D4. Distance D3 is the same as the thickness of the polysilicon layer discussed supra in reference to FIG.1 A and (D4-D3) is the thickness of the gate dielectric layer discussed supra in reference to FIG. 1A. FIGS. 5A and 5B are partial cross-sectional views illustrating common intermediate steps for fabricating doped polysilicon lines and gates according to the present invention. In FIG. 5A, polysilicon layer 135 (see FIG. 1D, 2D or 3D} is etched into gate electrodes 185A and 185B. Formation of gate electrodes 185A and 185B may be accomplished by one of any number of plasma etch processes selective to etch polysilicon over oxide well known in the art. In FIG. 5B, an oxidation is performed to simultaneously grow a thermal oxide layer 1 90A over sidewalls 1 95A and a top surface 200A of gate electrode 185A and a thermal oxide layer 1 90B over sidewalls 1 95B and a top surface 200B of gate electrode 185B. The width of gate electrode 185A at top surface 200A and the width of gate electrode 185B at top surface 200B are both about equal to W1. Gate electrode 185A is doped P type and gate electrode 185B is doped N type. Gate electrode 185B (and possibly gate electrode 185A depending upon which embodiment of the present invention is used prior to the thermal oxidation step) has also been nitrogenated by the nitrogen ion species ion implantation described supra. This reduces (retards) the thermal oxidation rate of N-doped polysilicon. In one example, the thermal oxidation rate of N-doped polysilicon is retarded to be about the same as the thermal oxidation rate of P-doped polysilicon. An example of a thermal oxidation is a furnace oxidation performed for in about a 97% O2 and about 3% HCL generating gas a temperature of about 750° C. for 35 minutes which will grow about 40 angstroms of Si)2 on <100> single-crystal silicon. The steps illustrated in FIGS. 7A through 7E are next performed. FIG. 6 is a partial cross-sectional view of a problem solved by the present invention. In FIG. 6, the situation that would otherwise prevail if the nitrogen species ion implantation had not been performed. After thermal oxidation, gate electrode 190C has a width W2 at a top surface 200C (where W2 is less than W1) because N-doped polysilicon oxidizes at a faster rate than P-doped polysilicon. The situation wherein the N-dopant concentration is higher near a top surface 200C of gate electrode 185C is illustrated. Table II illustrates the effect of nitrogen species ion implantation: TABLE II Nitrogen Implant Thermal Oxide Thickness Polysilicon Width at Top Energy N-doped P-doped N-doped P-doped and Dose Polysilicon Polysilicon Polysilicon Polysilicon NONE 149 Å 61 Å 13 nm 28 nm 6.3 Kev, 64 Å 58 Å 23 nm 27 nm 5E15 atm/cm2 6.3 Kev, 52 Å 58 Å 23 nm 30 nm 1E16 atm/cm2 FIGS. 7A through 7E are partial cross-sectional views illustrating common last steps for fabricating doped polysilicon lines and gates according to the present invention. FIG. 7A is identical to FIG. 5B. In FIG. 7B, dielectric spacers 205A and 205B are formed over thermal oxide layers 190A and 190B on sidewalls 195A and 195B of gate electrodes 185A and 185B respectively. Spacers 205A and 205B may be formed by deposition of a conformal material (for example, silicon nitride) followed by a reactive ion etch (RIE) to remove the conformal material from surfaces perpendicular to the direction of the ion flux. Next, well known in the art extension and/or halo and source drain ion implants are performed to P+ source drains 210 in N-well 105 and N+ source drains 215 in P-well 115. Additional spacers may be formed between various extension, halo and source/drain ion implants. In FIG. 7C, gate dielectric layer 125 is removed wherever the gate dielectric layer is not protected by gate electrodes 185A and 185B and by spacers 105A and 205B. (The gate dielectric on the sidewalls of the gate electrodes also protects the underlying gate dielectric layer.) Also, thermal oxide layer 190A and 190B on top surfaces 200A and 200B of gate electrodes 185A and 185B respectively is removed. Gate dielectric layer 125 and thermal oxide layer 190A and 190B removal may be accomplished, for example, using a dilute aqueous HF containing solution. In FIG. 7D a metal layer 220 is deposited. Metal layer 220 may be nickel, titanium, platinum or cobalt. In FIG. 7E, a portion of metal layer 220 in contact with gate electrodes 185A and 185B and with P+ source drains 210 and N+ source/drains 215 is converted to a metal silicide 225 by annealing and removing unreacted metal layer 220 by methods well known in the art. Fabrication of a PFET 230 and an NFET 235 having similar gate electrode linewidths and resistivity is now complete. Thus, the present invention provides a method of fabricating doped polysilicon lines and gates with improved linewidth control. The description of the embodiments of the present invention is given above for the understanding of the present invention. It will be understood that the invention is not limited to the particular embodiments described herein, but is capable of various modifications, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, it is intended that the following claims cover all such modifications and changes as fall within the true spirit and scope of the invention.

<SOH> BACKGROUND OF INVENTION <EOH>1. Field of the Invention The present invention relates to the field of semiconductor fabrication; more specifically, it relates a method of fabricating doped polysilicon lines and complementary metal-oxide-silicon (CMOS) doped polysilicon gates. 2. Background of the Invention Advanced CMOS devices utilize doped polysilicon lines and gates with metal silicide layers as a method of improving and matching the performance of N-channel field effect transistors (NFETs) and P-channel field effect transistors (PFETs). However, controlling the width and sheet resistance of oppositely doped polysilicon lines and gates has become more important and difficult as the widths of polysilicon lines and gates have decreased. Therefore, there is a need for a method of fabricating doped polysilicon lines and gates with improved linewidth control.

<SOH> SUMMARY OF INVENTION <EOH>A first aspect of the present invention is a method of fabricating a semiconductor structure, comprising: providing a substrate; forming a dielectric layer on a top surface of the substrate; forming a polysilicon layer on a top surface of the dielectric layer; implanting the polysilicon layer with N-dopant species, the N-dopant species essentially contained within the polysilicon layer; implanting the polysilicon layer with a nitrogen containing species, the nitrogen containing species about contained within the polysilicon layer. A second aspect of the present invention is a method of fabricating a semiconductor structure, comprising: (a) providing a substrate; (b) forming a dielectric layer on a top surface of the substrate; (c) forming a polysilicon layer on a top surface of the dielectric layer; (d) implanting a first portion of the polysilicon layer with N-dopant species, the N-dopant species about contained within the polysilicon layer; (e) implanting a second and different portion of the polysilicon layer with P-dopant species, the P-dopant species about contained within the polysilicon layer; (f) implanting the first portion of the polysilicon layer with a nitrogen containing species, the nitrogen containing species essentially contained within the polysilicon layer.

20041004

20071204

20060406

79226.0

H01L213205

GHYKA, ALEXANDER G

METHOD FOR FABRICATING DOPED POLYSILICON LINES

UNDISCOUNTED

ACCEPTED

H01L

ACCEPTED

TEXTURE ERROR RECOVERY METHOD USING EDGE PRESERVING SPATIAL INTERPOLATION

A method of recovering texture information for an error block in a video stream includes applying an edge detection spatial filter on blocks surrounding an error block to detect texture edges, each block containing a plurality of pixels, and identifying first pixels surrounding the error block having texture data above a predetermined threshold value, selecting first pixels and checking the texture data of pixels extending from the selected first pixel in a plurality of predetermined directions for determining a direction of the texture edge, accumulating the edge detection filtering results of pixels that are located on the texture edge in a selected direction, determining the filtering weights corresponding to each direction of the texture edge based on the filtering results of pixels checked in the predetermined directions, and reconstructing the texture of the error block in the spatial domain using weight filtering based on the texture data of surrounding pixels.

1. A method of recovering texture information for an error block in a video stream, the method comprising: locating an error block; applying an edge detection spatial filter on blocks surrounding the error block to detect texture edges, each block containing a plurality of pixels; generating filtering results of the plurality of pixels; identifying first pixels surrounding the error block having texture data above a predetermined threshold value; selecting first pixels one by one and checking the texture data of pixels extending from the selected first pixel in a plurality of predetermined directions for determining a direction of the texture edge; accumulating the filtering results of pixels that are located on the texture edge in a selected direction using a corresponding counter; determining filtering weights based on the accumulation results of each counter corresponding to the predetermined directions; and reconstructing the texture data of the error block in the spatial domain based on the texture data of surrounding pixels of the error block. 2. The method of claim 1, further comprising after checking the texture data of pixels extending from one of the first pixels in a selected direction, setting a flag corresponding to the selected direction to indicate that the selected direction has already been checked. 3. The method of claim 2, further comprising skipping checking the texture data of pixels in the selected direction if the flag corresponding to the selected direction has already been set. 4. The method of claim 1, wherein the texture data is checked for pixels in eight different directions. 5. The method of claim 4, wherein a 22.5-degree angle separates adjacent directions. 6. The method of claim 1, wherein selecting first pixels one by one comprises selecting successive first pixels in a row one by one from left to right, and then checking successive rows from top to bottom. 7. The method of claim 6, wherein each of the predetermined directions extends below or to the right of the selected first pixel. 8. The method of claim 1, further comprising stopping checking the texture data of pixels in the selected direction if a predetermined number of consecutive pixels are not located on the texture edge. 9. The method of claim 8, wherein the predetermined number of consecutive pixels is equal to 1. 10. The method of claim 8, wherein the predetermined number of consecutive pixels is equal to 2. 11. The method of claim 1, wherein the edge detection spatial filter applied to the blocks surrounding the error block is defined by the matrix M = [ - 1 - 1 - 1 - 1 8 - 1 - 1 - 1 - 1 ] 12. The method of claim 1, wherein the predetermined threshold value is equal to 64. 13. The method of claim 1, wherein the error block is reconstructed by weight filtering the texture data of the surrounding pixels of the error block.

BACKGROUND OF INVENTION 1. Field of the Invention The present invention relates to a method of recovering texture data in video streams, and more specifically, to a method of recovering texture data for error blocks in video streams using spatial interpolation. 2. Description of the Prior Art Video streams are composed of many macro blocks. It is inevitable that some of the blocks in a video stream may have errors when transmitting. The macro blocks containing errors are referred to as error blocks. Methods have been developed for reconstructing error blocks in order to clean up the video signal. The blocks surrounding the error block are analyzed, and the error block is reconstructed to be similar to the surrounding blocks. Each block contains a plurality of pixels. For the following disclosure, it will be assumed that each block is a set of 16×16 pixels. Please refer to FIG. 1. FIG. 1 is a diagram of a video frame 5 containing an error block 10. The error block 10 is shown in the video frame 5, surrounded by other blocks 12. The prior art method of reconstructing the error block 10 contains several steps. First of all, the method calculates a gradient for each pixel in the surrounding blocks 12. Thereafter, the texture edge is detected by comparing the pixel gradients to a threshold level. The gradient directions of the pixels in the surrounding blocks 12 fall into eight classes, which are illustrated in FIG. 2. Eight surrounding pixels 20 in FIG. 2, which are labeled 0 to 7, present eight different directions extending from a central pixel 15. Each of these eight directions covers an angle area of 22.5 degrees. For each of the pixels in surrounding blocks, the texture edge extending direction of one pixel can be calculated using its gradient direction. If the texture edge extending direction runs through the error block 10, a counter corresponding to that direction will be accumulated with the gradient magnitude of the pixel. Once the texture edge extension has been calculated for each of the pixels in the four surrounding blocks, the counter totals are used in calculating filtering weights. The error block 10 is then reconstructed by weight filtering its surrounding boundary pixels from blocks 12. The filtering weights correspond to the eight edge extending directions and further to the eight pixels shown in FIG. 2. To perform the weight filtering, the texture data of the surrounding pixels of the error pixel will be multiplied with corresponding weights and then averaged for the reconstructed result. The weight filtering is performed for each pixel of the error block 10 to reconstruct the whole error block finally. Unfortunately, the calculating the texture edge extension for each of the 8 sections is complicated and requires heavy computation. SUMMARY OF INVENTION It is therefore an objective of the claimed invention to provide a method of interpolating texture information for an error block in a video stream in order to solve the above-mentioned problems. According to the claimed invention, a method of recovering texture information for an error block in a video stream includes locating an error block, applying an edge detection spatial filter on blocks surrounding the error block to detect texture edges, each block containing a plurality of pixels, generating filtering results of the plurality of pixels, and identifying first pixels surrounding the error block having texture data above a predetermined threshold value. The method also includes selecting first pixels one by one and checking the texture data of pixels extending from the selected first pixel in a plurality of predetermined directions for determining a direction of the texture edge, accumulating the filtering results of pixels that are located on the texture edge in a selected direction using a corresponding counter, determining filtering weights based on the accumulation results of each counter corresponding to the predetermined directions, and reconstructing the texture data of the error block in the spatial domain based on the texture data of surrounding pixels of the error block. It is an advantage of the claimed invention that checking the texture data of blocks extending from the first pixels in the plurality of predetermined directions is simplified in the present invention for reducing complexity of the texture recovery operation and for reducing the number of calculations required. The claimed invention does not require gradients to be calculated, and thereby requires fewer overall calculations be performed. These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram of a video frame containing an error block. FIG. 2 presents the relationship between the surrounding pixels of the error pixel with the edge extending directions. FIG. 3 illustrates checking texture edges in a plurality of directions according to the present invention. DETAILED DESCRIPTION The present invention method of recovering texture data for error blocks in video streams using spatial interpolation starts out by identifying error blocks. This identification can be performed using any of the prior art identification methods. Once an error block has been identified, a matrix is applied to the four surrounding blocks for filtering the surrounding blocks with an edge detection spatial filter. Although many different matrices could be applied, matrix M is shown below as an example. M = [ - 1 - 1 - 1 - 1 8 - 1 - 1 - 1 - 1 ] A threshold is set to detect the texture edge by only considering pixels whose filtering results are above a threshold value. As an example, the threshold may be set equal to 64. Please refer to FIG. 3. FIG. 3 illustrates checking texture edges in a plurality of directions according to the present invention. After the pixels with its filtering result above the threshold have been calculated, the texture edge pixels are checked one by one in eight different directions D0-D7 to determine if other pixels in that direction also lie on the texture edge. Pixels are checked one at a time from left to right in a row. Once a row is completed, the next row down is checked until the pixels in all of the rows have been checked. As shown in FIG. 3, a current pixel 40 is the texture edge pixel currently being checked. The eight directions D0-D7 extend to the right of the current pixel 40 or down from the current pixel 40. None of the eight directions D0-D7 extend directly to the left of the current pixel 40 or up from the current pixel 40. This is because pixels above the current pixel 40 or directly to the left of the current pixel 40 have already been checked by previous iterations. In a preferred embodiment of the present invention, eight directions D0-D7 are used, where a 22.5-degree angle separates adjacent directions. There is still a limiting condition, however. The checking on the directions Dx (x=0, 1, . . . 7) should be skipped if the edge extending on this direction cannot go through the error block area. As mentioned above, the eight directions are used to determine if other pixels in those directions also lie on the texture edge. To avoid repeated calculations, a group of flags can be used to record whether groups of pixels have already been checked in a specified direction. If the flag indicates that all pixels in that direction have already been checked, those pixels do not need to be checked again. In order to reduce spatial noise, the checking of texture edge pixels in a specific direction will be stopped if a predetermined number of consecutive pixels are found not to be on the texture edge. For strictly reducing noise, the predetermined number of consecutive pixels is set to be a low number. For example in directions D0, D2, D4, and D6, the predetermined number of consecutive pixels can be set as 2 pixels. For directions D1, D3, D5, and D7, the predetermined number of consecutive pixels can be set as 1 pixel. For less strictly reducing noise, the number of consecutive pixels can be set to larger numbers. As a result, if the current pixel 40 is an isolated edge pixel, which means no pixel is found on the texture edge after checking for this pixel, the pixel 40 will be thought as a noise pixel and not considered in subsequent process. In general, once the eight directions extending from the current pixel 40 have been checked, the filtering results of texture edge pixels located on that direction would be accumulated with a counter corresponding to that direction. Based on the accumulation results, the filtering weights corresponding to the eight edge extending directions can be calculated. Thereafter, the texture of the error block is reconstructed similarly using the same weight filtering as that in the prior art. By the reconstruction of the texture of the error block, the overall quality of the video stream will be improved, and will look less noisy. In contrast to the prior art, the present invention does not require gradients to be calculated, and thereby requires fewer overall calculations be performed. Checking the texture data of blocks extending from the current pixel in the plurality of predetermined directions is simplified in the present invention for reducing complexity of the texture recovery operation and for reducing the number of calculations required. Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.

<SOH> BACKGROUND OF INVENTION <EOH>1. Field of the Invention The present invention relates to a method of recovering texture data in video streams, and more specifically, to a method of recovering texture data for error blocks in video streams using spatial interpolation. 2. Description of the Prior Art Video streams are composed of many macro blocks. It is inevitable that some of the blocks in a video stream may have errors when transmitting. The macro blocks containing errors are referred to as error blocks. Methods have been developed for reconstructing error blocks in order to clean up the video signal. The blocks surrounding the error block are analyzed, and the error block is reconstructed to be similar to the surrounding blocks. Each block contains a plurality of pixels. For the following disclosure, it will be assumed that each block is a set of 16×16 pixels. Please refer to FIG. 1 . FIG. 1 is a diagram of a video frame 5 containing an error block 10 . The error block 10 is shown in the video frame 5 , surrounded by other blocks 12 . The prior art method of reconstructing the error block 10 contains several steps. First of all, the method calculates a gradient for each pixel in the surrounding blocks 12 . Thereafter, the texture edge is detected by comparing the pixel gradients to a threshold level. The gradient directions of the pixels in the surrounding blocks 12 fall into eight classes, which are illustrated in FIG. 2 . Eight surrounding pixels 20 in FIG. 2 , which are labeled 0 to 7 , present eight different directions extending from a central pixel 15 . Each of these eight directions covers an angle area of 22.5 degrees. For each of the pixels in surrounding blocks, the texture edge extending direction of one pixel can be calculated using its gradient direction. If the texture edge extending direction runs through the error block 10 , a counter corresponding to that direction will be accumulated with the gradient magnitude of the pixel. Once the texture edge extension has been calculated for each of the pixels in the four surrounding blocks, the counter totals are used in calculating filtering weights. The error block 10 is then reconstructed by weight filtering its surrounding boundary pixels from blocks 12 . The filtering weights correspond to the eight edge extending directions and further to the eight pixels shown in FIG. 2 . To perform the weight filtering, the texture data of the surrounding pixels of the error pixel will be multiplied with corresponding weights and then averaged for the reconstructed result. The weight filtering is performed for each pixel of the error block 10 to reconstruct the whole error block finally. Unfortunately, the calculating the texture edge extension for each of the 8 sections is complicated and requires heavy computation.

<SOH> SUMMARY OF INVENTION <EOH>It is therefore an objective of the claimed invention to provide a method of interpolating texture information for an error block in a video stream in order to solve the above-mentioned problems. According to the claimed invention, a method of recovering texture information for an error block in a video stream includes locating an error block, applying an edge detection spatial filter on blocks surrounding the error block to detect texture edges, each block containing a plurality of pixels, generating filtering results of the plurality of pixels, and identifying first pixels surrounding the error block having texture data above a predetermined threshold value. The method also includes selecting first pixels one by one and checking the texture data of pixels extending from the selected first pixel in a plurality of predetermined directions for determining a direction of the texture edge, accumulating the filtering results of pixels that are located on the texture edge in a selected direction using a corresponding counter, determining filtering weights based on the accumulation results of each counter corresponding to the predetermined directions, and reconstructing the texture data of the error block in the spatial domain based on the texture data of surrounding pixels of the error block. It is an advantage of the claimed invention that checking the texture data of blocks extending from the first pixels in the plurality of predetermined directions is simplified in the present invention for reducing complexity of the texture recovery operation and for reducing the number of calculations required. The claimed invention does not require gradients to be calculated, and thereby requires fewer overall calculations be performed. These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

20041011

20080226

20060413

58639.0

G06K940

ALAVI, AMIR

TEXTURE ERROR RECOVERY METHOD USING EDGE PRESERVING SPATIAL INTERPOLATION

UNDISCOUNTED

ACCEPTED

G06K

ACCEPTED

NON-SKID MODULAR PLASTIC CONVEYOR BELT

A modular conveyor belt constructed of modules having upstanding ribs, each in the form of textured upper ridge structure atop an elongated rib base. Consecutive ribs are spaced apart laterally on the top surface of the modules. Longitudinal slots between laterally consecutively ribs admit the fingers of transfer plates for smooth transfer of articles on and off the belt. The textured rib structure includes rows of teeth, truncated pyramids or cones, corrugated structure, and sinuous beads atop which articles are supported with little slipping in wet conditions.

1. A conveyor belt module comprising: a module body extending longitudinally from a first end to a second end, laterally from a first side edge to a second side edge, and in thickness from a top side to a bottom side, the module body comprising: a first set of hinge eyes spaced apart laterally along the first end; a second set of hinge eyes spaced apart laterally along the second end; a flat surface on the top side; a plurality of laterally spaced longitudinal ribs including a solid elongated base extending outward of the flat surface and textured upper ridge structure atop the base to support conveyed articles. 2. A conveyor belt module as in claim 1 wherein the textured upper ridge structure comprises a longitudinal row of truncated rectangular pyramids. 3. A conveyor belt module as in claim 1 wherein the textured upper ridge structure comprises a longitudinal row of truncated cones. 4. A conveyor belt module as in claim 1 wherein the textured upper ridge structure comprises a longitudinal row of teeth. 5. A conveyor belt module as in claim 4 wherein the textured upper ridge structure of each rib comprises two longitudinal rows of teeth separated laterally by a longitudinal groove. 6. A conveyor belt module as in claim 1 wherein the textured upper ridge structure comprises a longitudinal row of alternating crests and valleys. 7. A conveyor belt module as in claim 6 wherein the crests and valleys are aligned along axes oblique to the longitudinal direction of the rib. 8. A conveyor belt module as in claim 1 wherein the textured upper ridge structure comprises a longitudinal row of corrugations. 9. A conveyor belt module as in claim 1 wherein the textured upper ridge structure comprises a sinuous bead upstanding from the base. 10. A modular conveyor belt comprising a plurality of conveyor belt modules as in claim 1 connected together edge to edge and end to end into a series of consecutive rows of belt modules interconnected by hinge rods received in lateral passageways formed in the aligned hinge eyes of consecutive rows of belt modules. 11. A conveyor belt module comprising: a module body extending longitudinally from a first end to a second end, laterally from a first side edge to a second side edge, and in thickness from a top side to a bottom side, the module body comprising: a first set of hinge eyes spaced apart laterally along the first end; a second set of hinge eyes spaced apart laterally along the second end; a flat surface on the top side; a plurality of longitudinal rows of truncated rectangular pyramids extending outwardly of the flat surface and defining notches between consecutive pyramids in each row, wherein each row is spaced laterally from another row to form a longitudinal slot between consecutive rows, wherein the longitudinal dimension of the notches is less than the lateral dimension of the slots between consecutive rows. 12. A conveyor belt module as in claim 11 wherein the lateral dimension of the slots is at least as great as the lateral dimension of the pyramids. 13. A conveyor belt module as in claim 11 wherein the total number of hinge eyes in the first and second sets equals the number of longitudinal rows. 14. A conveyor belt module as in claim 11 wherein the hinge eyes include a top portion coplanar with the flat surface and wherein one of the pyramids in each row extends from the top portion of a hinge eye. 15. A conveyor belt module as in claim 11 wherein each truncated rectangular pyramid has a rectangular base and a rectangular top face. 16. A conveyor belt module as in claim 15 wherein the area of the rectangular top face of each pyramid is less than the area of the rectangular base. 17. (canceled) 18. (canceled) 19. A conveyor belt module as in claim 17 wherein the notches are V-shaped. 20. A conveyor belt module as in claim 17 wherein at least some of the notches of one row are generally aligned laterally with notches of the other rows to form a lateral line of sight through the aligned notches from the first side edge of the module body to the second side edge. 21. A modular conveyor belt comprising a plurality of conveyor belt modules as in claim 11 connected together edge to edge and end to end into a series of consecutive rows of belt modules interconnected by hinge rods received in lateral passageways formed in the aligned hinge eyes of consecutive rows of belt modules. 22. A conveyor belt module comprising: a module body extending longitudinally from a first end to a second end, laterally from a first side edge to a second side edge, and in thickness from a top side to a bottom side, the module body comprising: a first set of hinge eyes spaced apart laterally along the first end; a second set of hinge eyes spaced apart laterally along the second end; a flat surface on the top side; a plurality of laterally spaced longitudinal ribs extending outwardly of the flat surface and having laterally spaced first and second side walls, wherein each rib is characterized by longitudinally spaced notches extending through the rib from the first side wall to the second side wall. 23. A conveyor belt module as in claim 22 wherein each rib is further characterized by a longitudinal groove extending the length of the rib between the first side wall and the second side wall. 24. A conveyor belt module as in claim 22 wherein the total number of hinge eyes in the first and second sets equals the number of longitudinal ribs. 25. A conveyor belt module as in claim 22 wherein the hinge eyes include a top portion coplanar with the flat surface and wherein each rib extends onto the top portion of a hinge eye. 26. A conveyor belt module as in claim 22 wherein each rib defines a plurality of teeth separated by the notches. 27. A conveyor belt module as in claim 26 wherein each tooth forms a truncated rectangular pyramid. 28. A conveyor belt module as in claim 22 wherein the notches are V-shaped. 29. A conveyor belt module as in claim 28 wherein the vertices of the V-shaped notches are disposed slightly above the flat surface on the top side of the module body. 30. A conveyor belt module as in claim 22 wherein at least some of the notches of one rib are generally aligned laterally with notches of the other ribs to form a lateral line of sight through the aligned notches from the first side edge of the module body to the second side edge. 31. A modular conveyor belt comprising a plurality of conveyor belt modules as in claim 22 connected together edge to edge and end to end into a series of consecutive rows of belt modules interconnected by hinge rods received in lateral passageways formed in the aligned hinge eyes of consecutive rows of belt modules. 32. A conveyor belt module comprising: a module body extending longitudinally from a first end to a second end, laterally from a first side edge to a second side edge, and in thickness from a top side to a bottom side, the module body comprising: a first set of hinge eyes spaced apart laterally at the first end; a second set of hinge eyes spaced apart laterally at the second end; a plurality of teeth arranged at the top side into a plurality of longitudinal rows of teeth separated by longitudinal slots extending longitudinally along the top side, wherein each tooth defines with a consecutive tooth on a row a notch that separates the consecutive teeth longitudinally and wherein the longitudinal dimension of the notches is less than the lateral dimension of the slots. 33. A conveyor belt module as in claim 32 wherein the total number of hinge eyes in the first and second sets equals the number of longitudinal rows of teeth. 34. A conveyor belt module as in claim 32 further comprising a flat surface at the top side of the module and wherein the hinge eyes include a top portion coplanar with the flat surface and wherein one of the teeth in each row extends from the top portion of a hinge eye. 35. A conveyor belt module as in claim 32 wherein each tooth is in the form of a rectangular pyramid. 36. A conveyor belt module as in claim 32 wherein each tooth includes a rectangular base at the bottom and a flat top face. 37. A conveyor belt module as in claim 36 wherein the area of the top face is less than the area of the rectangular base. 38. A conveyor belt module as in claim 32 wherein each tooth has a base at the bottom and an opposite top face and, between the base and the top face, a pair of opposite side walls laterally spaced from each other and a front wall and an opposite rear wall longitudinally spaced from each other. 39. A conveyor belt as in claim 38 wherein each of the side walls, the front wall, and the rear wall tapers toward its opposite wall with distance from the base. 40. (canceled) 41. (canceled) 42. A conveyor belt module as in claim 32 wherein the notches are V-shaped. 43. A conveyor belt module as in claim 32 wherein at least some of the notches of one row are generally aligned laterally with notches of the other rows to form a lateral line of sight through the aligned notches front the first side edge of the module body to the second side edge. 44. A modular conveyor belt comprising a plurality of conveyor belt modules as in claim 32 connected together edge to edge and end to end into a series of consecutive rows of belt modules interconnected by hinge rods received in lateral passageways formed in the aligned hinge eyes of consecutive rows of belt modules.

BACKGROUND The invention relates generally to power-driven conveyors and, more particularly, to modular plastic conveyor belts having a skid-proof top surface. Modular plastic conveyor belts with raised ribs are used with finger transfer plates or combs to transfer articles smoothly or passengers safely off the end of a conveyor belt. The fingers of the transfer plate extend into slots between raised longitudinal ribs formed on the conveying side of the conveyor belt. The ribs support conveyed articles, which are stripped from the end of the belt carryway by the fingers. The fingers partly occlude the gap that would exist between the end of the belt and a toothless transfer plate to prevent debris from dropping into the drive mechanism of the belt. The flat top surfaces of the ribs, however, do not make for a high-friction surface. For that reason, conventional raised rib belts are not often used in inclines, declines, or wet applications in which a conveyed article is susceptible to slipping along the ribbed conveying surface. Thus, there is a need for a conveyor belt that provides a non-skid surface on inclines or declines or in a wet environment. SUMMARY This need and other needs are satisfied by modular conveyor belts constructed of modules embodying features of the invention. In a first version of the invention, the module comprises a module body that extends longitudinally from a first end to a second end, laterally from a first side edge to a second side edge, and in thickness from a top side to a bottom side. The module body has a first set of hinge eyes spaced apart laterally along the first end and a second set along the second end. Longitudinal rows of truncated rectangular pyramids extend outward of a flat surface on the top side of the module body. Each row of pyramids is spaced laterally from another row to form a longitudinal slot between consecutive rows. In another version of the invention, a conveyor belt module comprises a module body that extends longitudinally from a first end to a second end, laterally from a first side edge to a second side edge, and in thickness from a top side to a bottom side. A first set of hinge eyes is spaced apart laterally along the first end; a second set, along the second end. The top side has a flat surface. Laterally spaced longitudinal ribs extend outward of the flat surface. The ribs have laterally spaced first and second side walls. Each rib is characterized by longitudinally spaced notches extending through the rib from the first side wall to the second side wall. In yet another version, a conveyor belt module comprises a module body extending longitudinally from a first end to a second end, laterally from a first side edge to a second side edge, and in thickness from a top side to a bottom side. The module body includes a first set of hinge eyes spaced apart laterally at the first end and a second set of hinge eyes spaced apart laterally at the second end. Teeth are arranged at the top side into a plurality of longitudinal rows. The teeth extend outward at the top side. Each tooth defines with a consecutive tooth on a row a notch that separates the consecutive teeth longitudinally. In still another version of the invention, a conveyor belt module comprises a module body that extends longitudinally from a first end to a second end, laterally from a first side edge to a second side edge, and in thickness from a top side to a bottom side. A first set of hinge eyes is spaced apart laterally along the first end; a second set, along the second end. The top side has a flat surface. Laterally spaced longitudinal ribs have a solid elongated base that extends outward of the flat surface. Textured upper ridge structure atop the base supports conveyed articles. In another aspect of the invention, belt modules of the various versions are connected together edge to edge and end to end into a series of consecutive rows of belt modules interconnected by hinge rods received in lateral passageways formed in the aligned hinge eyes of consecutive rows of belt modules. BRIEF DESCRIPTION OF THE DRAWINGS These features and aspects of the invention, as well as its advantages, are better understood by referring to the following description, appended claims, and accompanying drawings, in which: FIG. 1 is an isometric view of a portion of a modular conveyor belt constructed of belt modules embodying features of the invention; FIG. 2 is a pictorial view of an interior belt module usable in the belt of FIG. 1; FIG. 3 is a front elevation view of the module of FIG. 2; FIG. 4 is an isometric view of a portion of a conveyor belt as in claim 1 engaged by a finger transfer plate; FIG. 5 is a pictorial view of a portion of another version of a ribbed module usable in a belt as in FIG. 1 and embodying features of the invention including an oblique pattern of crests and valleys forming the ridge of the rib; FIG. 6 is a pictorial view of yet another version of a ribbed module usable in a belt as in FIG. 1 and embodying features of the invention including a pair of rows of teeth forming the ridge of each rib; FIG. 7 is a pictorial view of a portion of another version of a ribbed module usable in a belt as in FIG. 1 and embodying features of the invention including a longitudinal row of truncated cones forming the ridge of the rib; and FIG. 8 is a pictorial view of another version of a ribbed module usable in a belt as in FIG. 1 and embodying features of the invention including a sinuous bead forming the ridge of the rib. DETAILED DESCRIPTION A portion of a conveyor belt embodying features of the invention is shown in FIG. 1. The conveyor belt 10 is constructed of a series of rows 12, 12′ of belt modules arranged side by side in the row. The modules include short left-side edge modules 14 and long left-side edge modules 14′, short right-side edge modules 15 and long right-side edge modules 15′, and interior modules 16. The modules are preferably arranged in a bricklay pattern, in which all the even rows 12 are identical to each other, and all the odd rows 12′ are identical to each other. Each module 14, 15, 16 extends in a longitudinal direction, that is, in the direction of belt travel 18, from a first leading end 20 to a second trailing end 21. Sets of hinge eyes 22, 22′ are spaced apart laterally along the leading and trailing ends of the modules. The leading hinge eyes of a trailing row of belt modules are interleaved with the trailing hinge eyes of a leading belt row. Apertures 24 in the interleaved hinge eyes between consecutive rows are aligned to form a lateral passageway along the width of the belt. A hinge rod 26, received in the passageway, connects consecutive rows together at a hinge joint 28 at which the belt can articulate as it wraps around a drive or idler sprocket or backbends about shoes or rollers in a return path. The edge modules 14, 14′, 15, 15′ include an edge portion 30, 30′ that may include a cavity 32 for a plug or other rod retention device to confine the hinge rod within the belt. The edge portions 30, 30′ in this example have a generally smooth, flat top, unlike the interior portions of the belt, which have a raised structure. The flat top portion is used to smoothly engage shoes or rollers that support the belt and minimize sag in the belt's return path and to admit conveyor structure along the carryway to overlap the side edges of the belt to a height that is level with the raised structure. The modules are preferably made of thermoplastic materials, such as polypropylene, polyethylene, acetal, or composite materials including fibers for strength in an injection-molding process. The hinge rods may be stainless steel or made of molded or extruded plastic materials. The basic structure of the modules shown is similar to that of the Series 1200 modular plastic belt manufactured and sold by Intralox, L.L.C., of Harahan, La., USA. The interior module 16 shown in FIGS. 2 and 3 illustrates the non-skid top of the belt in greater detail. The body of the module extends longitudinally from a first end 20 to a second end 21 and laterally from a first side edge 32 to an opposite second side edge 33. The module body extends in thickness from a bottom side 34 to a top side 35. The top side is characterized by a generally flat surface 36 from which ribs 38 in the form of longitudinal rows of teeth 40 extend outward of the flat surface. In this example, each row includes six teeth in the form of truncated rectangular pyramids with rectangular top faces 42 having smaller areas than the bases 44 of the teeth. The teeth form a textured upper rib structure atop the ribs. The bases of the teeth may rest on a long rectangular pedestal, or rib base, 46 or directly on the flat surface of the module. The rib base is solid, without voids. The teeth have opposite side walls 47, 47′ separated laterally and defining the thickness 48 of the teeth. Perpendicular to the side walls are a front wall 49 and a rear wall 49′. To simplify molding of the modules, the walls are preferably tapered, making the teeth narrower at the top than at the base. V- or U-shaped notches 50 extend through the ribs from side wall to side wall to form the tooth-like structure. The notches are spaced apart longitudinally on each rib, generally at equal intervals to form the six teeth of more or less equal top area. The vertices 53 of the notches shown in FIG. 2 do not extend to the flat top surfaces of the module, but could extend to the flat surfaces. In this example, notches in laterally consecutive ribs are generally aligned longitudinally to provide a lateral line of sight 51 through aligned notches across the width of the belt. But the notches could be longitudinally staggered and provide no such line of sight. In the preferred version shown, the leading 22 and trailing 22′ hinge eyes are laterally offset from each other. A row of teeth is associated with each hinge eye. In this way, the total number of hinge eyes equals the number of ribs. The inward top portion 52 of each hinge eye is generally coplanar with and merely an extension of the flat top surface of the module body. One of the teeth of each row extends out and onto the top portion of the associated hinge eye. This maintains better uniformity and minimizes gaps in the pattern of teeth at the hinge joints of the belt of FIG. 1. Consecutive ribs are longitudinally offset from each other in accordance with their extension onto their associated hinge eyes. As shown best in FIGS. 3 and 4, the ribs are spaced apart laterally across longitudinal slots 54. Each slot is wide enough to accommodate a finger 60 of a finger transfer plate 61 at the entrance and exit ends of a conveyor carryway path. A front lip 62 of the transfer plate is generally level with or, more commonly, above the top support faces 42 of the teeth to strip articles or allow trip-free personal egress off the conveyor belt. Preferably, as shown in FIG. 2, the width, or lateral dimension, of the slots is greater than the longitudinal dimension of the notches from tooth to tooth. Another version of belt module is shown in FIG. 5. The module 64 differs from the previous version in that the textured upper ridge structure atop the base of each rib is a series of crests 66 and valleys, or notches, 67 forming corrugations or triangular teeth along the rib. The axes 68 of the crests and valleys are oblique to the longitudinal direction of the module. Laterally alternate ribs 69, 69′, in this version, are arranged on axes that are mirror images of each other about the longitudinal direction. FIG. 6 shows yet another example of a belt module usable in a conveyor belt as in FIG. 1. In this module 70, each rib 72, 72′ has two longitudinal rows of teeth 74, 74′ separated laterally by a longitudinal groove 76. Longitudinally spaced notches 78 separate the teeth in each row. Another example of a non-skid module with textured structure atop ribs is shown in FIG. 7. The module 80 has parallel rows of ribs 82 separated laterally by slots 84. Each rib includes an elongated base 86 topped with a series of projections in the form of truncated cones 88 with flat top faces 89 for supporting articles and presenting a non-skid surface. Yet another version of module that can be used in a non-skid conveyor belt as in FIG. 1 is shown in FIG. 8. Like other versions, the module 90 has a plurality longitudinal ribs 92 spaced apart laterally by slots that accommodate the fingers of a transfer plate. Each rib has an elongated base portion 94 extending from a flat surface 96 of the module body. Running generally along the length of the rib and forming its upper ridge structure is a sinuous bead 98. The corrugated pattern of the bead provides an effective non-skid pattern. Unlike continuous, broad, flat-topped ribs that are often used to convey articles, the generally uniform pattern of toothed ribs and other textured upper ridge structures provides a non-skid surface that is especially effective in wet environments and on inclines and declines. The notches between the teeth, the other variations in structure at the ridges of the ribs, and the slots between rows provide gaps that help inhibit articles atop the ribs from sliding freely on the belt. And the raised-rib structure avoids the problems encountered in wet environments by belts that have a generally continuous conveying surface on which water can accumulate and form a slick track for conveyed articles. Thus, the invention has been shown with respect to a preferred version, but other versions are possible. For example, longer belt modules with more than six teeth per row could be made. As another example, the rib density could be greater or less than one rib per hinge eye on each module. As yet another example, the top flat surface of the belt could be perforated to allow water to drain through it. So, as these few examples suggest, the scope and spirit of the claims is not meant to be limited to the preferred version described in detail.

<SOH> BACKGROUND <EOH>The invention relates generally to power-driven conveyors and, more particularly, to modular plastic conveyor belts having a skid-proof top surface. Modular plastic conveyor belts with raised ribs are used with finger transfer plates or combs to transfer articles smoothly or passengers safely off the end of a conveyor belt. The fingers of the transfer plate extend into slots between raised longitudinal ribs formed on the conveying side of the conveyor belt. The ribs support conveyed articles, which are stripped from the end of the belt carryway by the fingers. The fingers partly occlude the gap that would exist between the end of the belt and a toothless transfer plate to prevent debris from dropping into the drive mechanism of the belt. The flat top surfaces of the ribs, however, do not make for a high-friction surface. For that reason, conventional raised rib belts are not often used in inclines, declines, or wet applications in which a conveyed article is susceptible to slipping along the ribbed conveying surface. Thus, there is a need for a conveyor belt that provides a non-skid surface on inclines or declines or in a wet environment.

<SOH> SUMMARY <EOH>This need and other needs are satisfied by modular conveyor belts constructed of modules embodying features of the invention. In a first version of the invention, the module comprises a module body that extends longitudinally from a first end to a second end, laterally from a first side edge to a second side edge, and in thickness from a top side to a bottom side. The module body has a first set of hinge eyes spaced apart laterally along the first end and a second set along the second end. Longitudinal rows of truncated rectangular pyramids extend outward of a flat surface on the top side of the module body. Each row of pyramids is spaced laterally from another row to form a longitudinal slot between consecutive rows. In another version of the invention, a conveyor belt module comprises a module body that extends longitudinally from a first end to a second end, laterally from a first side edge to a second side edge, and in thickness from a top side to a bottom side. A first set of hinge eyes is spaced apart laterally along the first end; a second set, along the second end. The top side has a flat surface. Laterally spaced longitudinal ribs extend outward of the flat surface. The ribs have laterally spaced first and second side walls. Each rib is characterized by longitudinally spaced notches extending through the rib from the first side wall to the second side wall. In yet another version, a conveyor belt module comprises a module body extending longitudinally from a first end to a second end, laterally from a first side edge to a second side edge, and in thickness from a top side to a bottom side. The module body includes a first set of hinge eyes spaced apart laterally at the first end and a second set of hinge eyes spaced apart laterally at the second end. Teeth are arranged at the top side into a plurality of longitudinal rows. The teeth extend outward at the top side. Each tooth defines with a consecutive tooth on a row a notch that separates the consecutive teeth longitudinally. In still another version of the invention, a conveyor belt module comprises a module body that extends longitudinally from a first end to a second end, laterally from a first side edge to a second side edge, and in thickness from a top side to a bottom side. A first set of hinge eyes is spaced apart laterally along the first end; a second set, along the second end. The top side has a flat surface. Laterally spaced longitudinal ribs have a solid elongated base that extends outward of the flat surface. Textured upper ridge structure atop the base supports conveyed articles. In another aspect of the invention, belt modules of the various versions are connected together edge to edge and end to end into a series of consecutive rows of belt modules interconnected by hinge rods received in lateral passageways formed in the aligned hinge eyes of consecutive rows of belt modules.

20041013

20060926

20060413

67679.0

B65G1706

BIDWELL, JAMES R

NON-SKID MODULAR PLASTIC CONVEYOR BELT

UNDISCOUNTED

ACCEPTED

B65G

ACCEPTED

INTEGRATED CIRCUIT SELECTIVE SCALING

Methods, systems and program products are disclosed for selectively scaling an integrated circuit (IC) design: by layer, by unit, or by ground rule, or a combination of these. The selective scaling technique can be applied in a feedback loop with the manufacturing system with process and yield feedback, during the life of a design, to increase yield in early processes in such a way that hierarchy is preserved. The invention removes the need to involve designers in improving yield where new technologies such as maskless fabrication are implemented.

1. A method for selectively scaling an integrated circuit design layout, the method comprising the steps of: identifying a scaling target for at least one problem object of the design layout based on manufacturing information; defining technology ground rules and methodology constraints for each problem object; determining a scaling factor for each problem object; determining which at least one of a plurality of scaling techniques is to be applied to each problem object, and scaling each problem object with a respective at least one scaling technique and scaling factor; and in the case that assembly is required, performing placement and routing to assemble the design using the scaled problem object. 2. The method of claim 1, wherein the at least one problem object is selected from the group comprising: a layer, a region and a cell. 3. The method of claim 1, wherein the placement and routing performing step includes using an optimization-based hierarchical scaling program to produce a legal layout for each problem object. 4. The method of claim 1, wherein the scaling factor is at least one of: a compensation, a new ground rule and a scaling multiplier. 5. The method of claim 1, wherein the identifying step includes: manufacturing the design layout; testing the manufactured design layout and identifying at least one problem object that is a problem; and generating the manufacturing information. 6. The method of claim 5, wherein the testing step includes characterizing operation and identifying the at least one problem object by obtaining data indicating how well objects are able to be manufactured. 7. The method of claim 5, wherein the manufacturing information generating step includes generating the scaling target for the problem object. 8. The method of claim 1, further comprising the step of evaluating whether a new design layout including the scaled objects achieves an expected behavior. 9. A system for selectively scaling an integrated circuit design layout, the system comprising the steps of: means for identifying a scaling target for at least one problem object of the design layout based on manufacturing information; means for defining technology ground rules and methodology constraints for each problem object; means for determining a scaling factor for each problem object; means for determining which at least one of a plurality of scaling techniques is to be applied to each problem object, and scaling each problem object with a respective at least one scaling technique and scaling factor; and means for, in the case that assembly is required, performing placement and routing to assemble the design using the scaled problem object. 10. The system of claim 9, wherein the at least one problem object is selected from the group comprising: a layer, a region and a cell. 11. The system of claim 9, wherein the placement and routing performing means includes means for conducting an optimization-based hierarchical scaling to produce a legal layout for each problem object. 12. The system of claim 9, wherein the scaling factor is at least one of: a compensation, a new ground rule and a scaling multiplier. 13. The system of claim 9, wherein the identifying means includes: means for testing a manufactured design layout and identifying at least one problem object that is a problem; and means for generating the manufacturing information. 14. The system of claim 13, wherein the testing means includes means for characterizing operation and identifying the at least one problem object by obtaining data indicating how well objects are able to be manufactured. 15. The system of claim 13, wherein the manufacturing information generating means includes means for generating the scaling target for the problem object. 16. The system of claim 13, further comprising means for evaluating whether a new design layout including the scaled objects achieves an expected behavior. 17. A computer program product comprising a computer useable medium having computer readable program code embodied therein for selectively scaling an integrated circuit design layout, the program product comprising: program code configured to identify a scaling target for at least one problem object of the design layout based on manufacturing information; program code configured to define technology ground rules and methodology constraints for each problem object; program code configured to determine a scaling factor for each problem object; program code configured to determine which at least one of a plurality of scaling techniques is to be applied to each problem object, and scaling each problem object with a respective at least one scaling technique and scaling factor; and program code configured to, in the case that assembly is required, perform placement and routing to assemble the design using the scaled problem object. 18. The program product of claim 17, wherein the at least one problem object is selected from the group comprising: a layer, a region and a cell. 19. The program product of claim 17, wherein the placement and routing performing code includes program code configured to conduct an optimization-based hierarchical scaling to produce a legal layout for each problem object. 20. The program product of claim 17, wherein the scaling factor is at least one of: a compensation, a new ground rule and a scaling multiplier. 21. The program product of claim 17, wherein the identifying code includes: program code configured to test a manufactured design layout and identify at least one problem object that is a problem; and program code configured to generate the manufacturing information. 22. The program product of claim 21, wherein the testing code includes program code configured to characterize operation and identify the at least one problem object by obtaining data indicating how well objects are able to be manufactured. 23. The program product of claim 17, wherein the manufacturing information generating code includes program code configured to generate a scaling target for the problem object. 24. The program product of claim 17, further comprising program code configured to evaluate whether a new design layout including the scaled objects achieves an expected behavior. 25. A method for improving yield of an integrated circuit design layout during manufacturing, the method comprising the steps of: testing a manufactured design layout and identifying at least one problem object that is a problem; generating manufacturing information obtained during the testing; and feeding back the manufacturing information to a system for selective scaling of the design layout to improve yield using a scaling target for at least one problem object of the design layout based on the manufacturing information. 26. The method of claim 25, wherein the testing step includes characterizing operation by obtaining data indicating how well objects are able to be manufactured. 27. A system for improving yield of an integrated circuit design layout during manufacturing, the system comprising: means for testing a manufactured design layout and identifying at least one problem object that is a problem; means for generating manufacturing information including a scaling target for each problem object; and means for feeding back the manufacturing information to a system for selective scaling of the design layout to improve yield using a scaling target for at least one problem object of the design layout based on the manufacturing information. 28. The system of claim 27, wherein the testing means includes means for characterizing operation by obtaining data indicating how well objects are able to be manufactured. 29. A computer program product comprising a computer useable medium having computer readable program code embodied therein for improving yield of an integrated circuit design layout during manufacturing, the program product comprising: program code configured to test a manufactured design layout and identifying at least one problem object that is a problem; program code configured to generate manufacturing information including a scaling target for each problem object; and program code configured to feed back the manufacturing information to a system for selective scaling of the design layout to improve yield using a scaling target for at least one problem object of the design layout based on the manufacturing information. 30. The program product of claim 29, wherein the testing code includes program code configured to characterize operation by obtaining data indicating how well objects are able to be manufactured.

BACKGROUND OF THE INVENTION 1. Technical Field The present invention relates generally to integrated circuit design, and more particularly, to selectively scaling an integrated circuit design layout by: layer, region or cell, or a combination of these, for the purposes of increasing yield in early processes in such a way that hierarchy is preserved. 2. Related Art One way of modifying an existing very large scale integrated (VLSI) circuit design to increase its manufacturing yield is to spread wires and add redundant vias in order to decrease critical area and increase via reliability. However, in the early stages of a new manufacturing process, these post-layout modifications alone may not be sufficient to achieve the desired yield improvement. Another yield-enhancing modification to an existing layout is to relax the spacing and width tolerances, which can be accomplished by a geometric scaling process. A challenge arises, however, when this scaling is attempted on only certain design layers and in the presence of certain other geometric constraints or in the presence of hierarchy. For example, back-end-of-line (BEOL) layers might be chosen for scaling but without altering any device sizes, and with the requirement that the location of connections from the top-level wiring to the integrated-circuit package remain fixed. A simple linear geometric scaling (i.e., multiplying the coordinates of every object in the design database by a fixed scaling factor) is obviously inadequate if connectivity is to be maintained between layers that are scaled and layers that are not scaled. The problem of hierarchical scaling itself is difficult to solve. One approach is addressed in co-pending U.S. patent application Ser. No. 10/438,625 (currently pending), entitled “A Practical Method for Hierarchical-Preserving Layout Optimization of Integrated Circuit Layout,” which is hereby incorporated by reference. Another approach is selective scaling, an example of which is disclosed in U.S. Pat. No. 6,756,242 to Regan. Regan, however, teaches scaling an entire design with different scaling factors in an X direction and a Y direction, which is also inadequate if connectivity is to be maintained between layers. In semiconductor manufacturing, design layouts are completed with a set of fixed ground rules that are provided to the designers by the manufacturing organization. The ground rules describe process and lithography best estimates of what is manufacturable. The ground rules attempt to balance chip density on a wafer (aggressiveness) with what can be reliably manufactured (conservatism). During the lifetime of a technology process or a design, “learning” takes place through failure analysis on finished products and in the manufacturing line. If implemented, this learning can improve yields. For example, the ground rules may change to reflect the yield learning. Unfortunately, frequent or considerable changes cannot usually be made because implementation of any change is expensive because each requires designer involvement in modifying the design to reflect the new ground rules. More significantly, any design modification typically requires new masks, which are extremely expensive. Accordingly, design changes are historically only made very infrequently. Yield related design changes may be added if functional changes require new masks (i.e., if there are difficulties with the function or performance which require a new design iteration), or if there are significant yield issues which force a new design iteration in order to achieve cost targets. Future manufacturing and design environments, however, provide several important aspects that may allow significant improvement of this process: First, maskless lithography has been proposed for future technologies, which if implemented will eliminate the costs of additional mask sets for a changed design. Second, improved simulation and validation capabilities may provide the ability to do more “full-up” simulations of designs because of improved algorithms, parallel processing, and system architectures. In this fashion, selective scaling may be applied in a tightly coupled feedback loop with the manufacturing line with process and yield feedback, during the life of a design. In current manufacturing and design environments, limited mask lifespans offer the opportunity for periodic layout updates during the life of a design. In view of the foregoing, there is a need in the art to address the problems of the related art. SUMMARY OF THE INVENTION The invention includes methods, systems and program products for selectively scaling an integrated circuit (IC) design by: layer, region or cell, or a combination of these. The selective scaling technique can be applied in a feedback loop with the manufacturing system with process and yield feedback, during the life of a design, to increase yield in early processes in such a way that hierarchy is preserved. The invention removes the need to involve designers in improving yield. A first aspect of the invention is directed to a method for selectively scaling an integrated circuit design layout, the method comprising the steps of: identifying a scaling target for at least one problem object of the design layout based on manufacturing information; defining technology ground rules and methodology constraints for each problem object; determining a scaling factor for each problem object; determining which at least one of a plurality of scaling techniques is to be applied to each problem object, and scaling each problem object with a respective at least one scaling technique and scaling factor; and in the case that assembly is required, performing placement and routing to assemble the design using the scaled problem object. A second aspect is directed to a system for selectively scaling an integrated circuit design layout, the system comprising the steps of: means for identifying a scaling target for at least one problem object of the design layout based on manufacturing information; means for defining technology ground rules and methodology constraints for each problem object; means for determining a scaling factor for each problem object; means for determining which at least one of a plurality of scaling techniques is to be applied to each problem object, and scaling each problem object with a respective at least one scaling technique and scaling factor; and means for, in the case that assembly is required, performing placement and routing to assemble the design using the scaled problem object. A third aspect is directed to a computer program product comprising a computer useable medium having computer readable program code embodied therein for selectively scaling an integrated circuit design layout, the program product comprising: program code configured to identify a scaling target for at least one problem object of the design layout based on manufacturing information; program code configured to define technology ground rules and methodology constraints for each problem object; program code configured to determine a scaling factor for each problem object; program code configured to determine which at least one of a plurality of scaling techniques is to be applied to each problem object, and scaling each problem object with a respective at least one scaling technique and scaling factor; and program code configured to, in the case that assembly is required, perform placement and routing to assemble the design using the scaled problem object. A fourth aspect is directed to a method for improving yield of an integrated circuit design layout during manufacturing, the method comprising the steps of: testing a manufactured design layout and identifying at least one problem object that is a problem; generating a scaling target for each problem object based on manufacturing information obtained during the testing; and feeding back the manufacturing information to a system for selective scaling of the design layout to improve yield using a scaling target for at least one problem object of the design layout based on the manufacturing information. A fifth aspect of the invention is directed to a system for improving yield of an integrated circuit design layout during manufacturing, the system comprising: means for testing a manufactured design layout and identifying at least one problem object that is a problem; means for generating manufacturing information including a scaling target for each problem object; and means for feeding back the manufacturing information to a system for selective scaling of the design layout to improve yield using a scaling target for at least one problem object of the design layout based on the manufacturing information. A sixth aspect of the invention is directed to a computer program product comprising a computer useable medium having computer readable program code embodied therein for improving yield of an integrated circuit design layout during manufacturing, the program product comprising: program code configured to test a manufactured design layout and identifying at least one problem object that is a problem; program code configured to generate manufacturing information including a scaling target for each problem object; and program code configured to feedback the manufacturing information to a system for selective scaling of the design layout to improve yield using a scaling target for at least one problem object of the design layout based on the manufacturing information. The foregoing and other features of the invention will be apparent from the following more particular description of embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS The embodiments of this invention will be described in detail, with reference to the following figures, wherein like designations denote like elements, and wherein: FIG. 1 shows a block diagram of a selective scaling system and a manufacturing system benefiting from the scaling system according to one embodiment of the invention. FIG. 2 shows a flow diagram of operational methodology of the system of FIG. 1. FIG. 3 shows a flow diagram of operation of the manufacturing system of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION For purposes of organization only, the description includes the following headings: I. System Overview, II. Operational Methodology, III. Conclusion. I. System Overview With reference to the accompanying drawings, FIG. 1 is a block diagram of an integrated circuit (IC) design selective scaling system 100 according to one embodiment of the invention. System 100 includes a memory 112, a processing unit (PU) 114, input/output devices (I/O) 116 and a bus 118. A database 120 may also be provided for storage of data relative to processing tasks. Memory 112 includes a program product 122 that, when executed by PU 114, comprises various functional capabilities described in further detail below. Memory 112 (and database 120) may comprise any known type of data storage system and/or transmission media, including magnetic media, optical media, random access memory (RAM), read only memory (ROM), a data object, etc. Moreover, memory 112 (and database 120) may reside at a single physical location comprising one or more types of data storage, or be distributed across a plurality of physical systems. PU 114 may likewise comprise a single processing unit, or a plurality of processing units distributed across one or more locations. I/O 116 may comprise any known type of input/output device including a network system, modem, keyboard, mouse, scanner, voice recognition system, CRT, printer, disc drives, etc. Additional components, such as cache memory, communication systems, system software, etc., may also be incorporated into system 100. System 100 receives an IC design 200 to be legalized and outputs an improved IC design 202. It should be recognized that system 100 may be incorporated as a part of a larger IC design system or be provided as a separate system. As shown in FIG. 1, program product 122 may include a scaling target identifier 124, a constraint definer 126, a scaling factor creator 128, a scaling technique determinator 130, a placement/router module 132, an evaluator 134 and other system components 138. Other system components 138 may include any other necessary functionality not expressly described herein. It should be recognized that while system 100 has been illustrated as a standalone system, it may be included as part of a larger IC design system or a peripheral thereto. An IC design 200 is input to system 100, and an improved IC design 202 is output from system 100. Manufacturing system 400 will be described in greater detail below. II. Operational Methodology A. Overview Co-pending U.S. patent application Ser. No. 10/438,625, entitled “A Practical Method for Hierarchical-Preserving Layout Optimization of Integrated Circuit Layout,” describes a method for scaling different layers in an integrated circuit (IC) design layout by different scaling factors without creating so-called “pull-aparts,” i.e., situations where two touching shapes on the same layer do not touch after being scaled. In this application, a method is taught on how to apply these techniques to a hierarchical design by specifying constraints for interfaces between hierarchical design levels and by showing how the placement of hierarchical elements (e.g., libraries or macros) can be specified during the scaling. Additionally, the invention allows different functional components embedded in an overall design to be scaled differently, without the necessity for disassembly and reassembly. The invention also can be used to scale by selected regions of any size up to and including an entire chip, based on any selection criteria, e.g., pattern matching, hierarchy, name, etc. The invention thus allows for: a) the scaling itself to be an optimization process—some scaling targets will be met and some not met. This allows a designer to impose and obey certain methodology constraints (such as pin locations). b) In the case where sub-circuits grow as a consequence of the scaling, the placement of the circuits is modified to preserve layout topology. c) The scaling can be applied component by component, as a design is assembled, or the scaling can be applied to the fully assembled (placed and routed) design at the end. d) A very fine degree of control is allowed over the scaling—by component, by layer, or even by geographic location. The invention also includes a manufacturing yield improvement loop (FIGS. 2-3) that extends back to the original design, without involving the original designer. This loop can be run in real time in the manufacturing environment, or it can be applied when new masks are built. The advantage of this flow is that it makes the manufacturing/design feedback loop a tighter, more focused loop than currently exists. A cost target can be set for a design, and the size of the layout (chips per wafer) versus yield can be automatically adjusted throughout the life of the design and process, in order to meet that target. In a “maskless lithography” world, this optimization could be applied batch-to-batch in manufacturing. In a “mask” world, this optimization could be applied whenever a new mask set is needed. Given that mask lifespans are limited, a long-running design may go through multiple sets of masks. B. Selective Scaling Methodology Given a ground-rule correct hierarchical IC design layout and feedback from manufacturing describing known problems, the design layout is scaled by a scaling factor for each object, i.e., layer, region and/or cell-specific values. Scaling Techniques The selective scaling methodology may implement different scaling techniques depending on the parts to be scaled. For purposes of this invention, three different scaling techniques will be described. It should be recognized, however, that other now known or later developed scaling techniques may be implemented. The three scaling techniques include: Flat Scaling, Minimum Perturbation Compaction, and Scaling of Custom Circuitry. Since each of these scaling techniques is described in detail in other U.S. patent applications or otherwise known by those with ordinary skill in the art, details of each will not be made. a) Flat Scaling A flat scaling of library elements uses the technique described in U.S. patent application Ser. No. 10/438,625, entitled “A Practical Method for Hierarchical-Preserving Layout Optimization of Integrated Circuit Layout,” to scale the data using appropriate scale factors for different layers/regions. b) Minimum Perturbation Compaction For circuits with defined border methodology (e.g., RLMs, bit stacks) use, a longest-path analysis referred to as minimum perturbation (hereinafter “minpert”) compaction may be used to calculate the amount by which each sub-cell will grow. Minpert compaction is described in U.S. patent application Ser. No. 10/707,287, entitled “Circuit Area Minimization Using Scaling,” which is hereby incorporated by reference. In this technique, the placement location of each sub-cell is modified so that after expansion, their boundary shapes abut. Then, each macro circuit is scaled hierarchically. c) Scaling of Custom Circuitry With pure custom circuits, the macro is typically scaled in two passes. The first-pass scaling modifies shapes and transform locations. “Transform” refers to a location of a circuit in terms of an X value, a Y value, a mirror value and a rotation value. For example, a circuit may have location of X=5, Y=4, be mirrored about the X-axis and a 90° rotation value (in this example, a shape vertex at point 5, 4 would first move to 5, −4 with the mirroring, then move to 4, 5 when rotated +90 degrees). A transform location modification changes the outline of the shape, thus changing its position relative to its neighbors. In a second pass, transform locations are rounded to integer values and ground-rule fix-up is performed using the layout optimizer, i.e., to accommodate the neighboring shape requirements. 2. Selective Scaling Technique Turning to FIG. 2, operational methodology of system 100 according to one embodiment of the invention will now be described. In step S1, based on information from manufacturing, at least one scaling target for at least one object of the design layout is identified by scaling target identifier 126. An “object” as used herein means a layer, region and/or cell (i.e., one or more layers, one or more regions, one or more cells, or a combination of those) of the design layout. As used herein, a “cell” is any placeable part of an IC design, sometimes referred to as macros, cells, sub-cells, etc. In addition, in certain instances, an “object” may include the entire chip. This step may include manual identification of a layer, region and/or cell by, for example, a person familiar with the manufacturing process and yield issues. Alternatively, this step may be carried out by any now known or later developed automated failure analysis system that can identify a layer, region and/or unit that is causing yield issues and may be a target for scaling. In addition, step S1 may include determining how much scaling is ideally required. “Manufacturing information” may be any information usable to identify a scaling target for an object. Manufacturing information will be described in greater detail below. Problem objects are identified regardless of whether they relate to design-related layout patterns that are known to be difficult to manufacture, or process-related defects, e.g., lines, vias, or other structures on a particular level which are not printing well. In step S2, the technology ground rules are defined for each object having a scaling target. This step is required because the scaling may be applied to more than just layers. For example, spacing ground rules that apply to the object, e.g., wiring or pins, must be defined and obeyed. In addition, methodology constraints are defined. For example, cell boundaries that limit growth, pin shapes, pin position, wiring tracks, etc., are defined. In step S3, a scaling factor is determined for each object having a scaling target. “Scaling factor” can be any form of changing the design now known or later developed. For example, the scaling factor may be one or more of a compensation (e.g., grow this unit by 3%), a new ground rule (e.g., change spacing for this layer by 2 nm), a scaling multiplier (e.g., decrease units on this layer by a factor of 0.011), etc. In step S4, a determination is made as to which at least one of a plurality of scaling techniques is to be applied to each object. For example, for flat cells without a hierarchy (e.g., library cells), the object may be scaled using the Flat Scaling technique, i.e., the region is flattened, determine the hierarchy and scale according the Flat Scaling technique. The object may be, for example, a region having an X-Y space. It should be recognized that each object is evaluated individually in that an object may be positioned at one location which is to be scaled, and also at another location which is not to be scaled or may be scaled by another scaling factor. Another example is a cell with border methodology constraints, which may be composed of instances of sub-cells with abutting boundary shapes. In this case, the MinPert Compaction scaling technique may be appropriate. Each pure custom circuit will be scaled using the Pure Circuit scaling technique, i.e., in two passes. In step S5, two different operations may occur depending on whether the above-described methodology is applied to: a) the objects and the chip re-assembled, or b) to the whole assembled circuit. In the former case, standard placement and routing technology is used to assemble the design using the scaled objects. In one embodiment, this step includes using an optimization-based hierarchical program to produce a legal layout for each object. In the latter case, the selective scaling is applied to an entire assembled circuit, i.e., the chip is the object, which eliminates the need to rerun placement and routing. Step S6 represents an optional step in which the new design layout is evaluated by evaluator 134 to determine whether the expected behavior is achieved. Evaluator 134 may include software and/or hardware for comparing the new design layout to the old design layout, and a simulator to implement design intent information (defined below) and check tools to verify that the expected behavior is achieved. This step may be carried out after the new design layer is virtually generated, or after a manufacturing run. The process may then repeat, as shown in FIG. 2. 3. Example Implementations The following illustrative implementations are not exhaustive and, therefore, should not be considered limiting of the attached claims. In a first example, a particular library cell in a design may require scaling of certain levels. A second example includes a particular redundant via cell. For example, if a particular arrangement of vias was found to cause yield issues (perhaps due to an optical proximity correction (OPC) issue), the spacing or arrangement of this particular model could be changed in every occurrence. (OPC is a technique for improving printing of shapes, which is applied just before masks are made. OPC makes additions to or subtractions from difficult to print structures due to the optical effects and the small wavelength of light used. For example, an inside corner, like the bend in an “L,” tends to fill-in a little during printing, so those corners get little notches cut out. Outside corners like the end of a line tend to round-off, so they get a small extra bump added.) A third example includes a situation in which difficulty with only a particular metal layer (e.g., M1) in a chip is observed. In this case, a chip-wide scaling of just that metal layer is necessary. C. Application of Selective Scaling to Yield Learning The above-described method can be applied to yield learning in a manufacturing system 400 on a continuous basis, or as new masks are built using the following methodology. The following methodology would occur as part of step S1, described above. It should be recognized that manufacturing system 400 may include similar computer-based sub-system structures (i.e., PU, I/O, busses, program products, etc.) as scaling system 100. Referring to FIG. 3, in a step S101, a design layout is manufactured by conventional manufacturing equipment 402. This step includes sub-step S101A preparing the design layout for photolithography, i.e., conventional data prep and conversion for masks or maskless data for tools. This step may include provision of design “intent” information by a designer to the manufacturing organization. This intent information is used during simulation of changes to the actual layout shapes, in order to ensure correct performance and function if small layout changes are made. For example, performance and tuning information and/or power information can be provided. In particular, a layout indicates how an IC works statically, but not how it functions dynamically, i.e., how fast or how much power is consumed in a clock cycle. Intent information may include data regarding static behavior deductions from the layout, the anticipated dynamic behavior such as performance and power. Also, noise to neighboring circuits or circuit groupings could be a piece of intent information. Circuit groupings may indicate circuits arranged so that they do not all switch simultaneously, because if they did it would cause a substantial voltage drop on a particular power bus so that some might not function correctly. In sub-step S101B, parts are manufactured. In step S102, testing is conducted by conventional testing equipment 404. In one embodiment, testing includes characterizing operation by obtaining data indicating how well objects or features are able to be manufactured. For example, line monitors (e.g., kerfs or special wafers) may measure the ability of the process to print embedded lines at a particular pitch. In another example, kerf structures could monitor the performance of types of via combinations for printability. At step S103, manufacturing information is generated by manufacturing information generator (MI) generator 406, and fed back to system 100 by any now known or later developed communications mechanism 408, e.g., a network. MI generator 406 may include any mechanism to generate the manufacturing information including, for example, mechanisms for determining when certain parameters exceed a threshold. In terms of parameters, manufacturing information may include, for example: a) Layers that should be scaled up to larger sizes or pitches because of unacceptable defects on those layers; b) Layers that can be scaled down to smaller sizes or pitches because of unexpectedly good manufacturability; c) Regions of a design that should be scaled up to a larger size in order to minimize systematic defects in these particular regions; d) Regions of a design that can be scaled down to a smaller size due to unexpectedly low defect densities in those regions; e) Cells that cannot be placed next to one another due to inappropriate interactions; and/or f) Cells that require modification to be placed next to one another to be more independent or tolerant of neighboring cells. Relative to the above described example in which line monitors measure the ability of the process to print embedded lines at a particular pitch: if the printable pitch drifts slightly, manufacturing information can be generated (next step) such that the above-described selective scaling can be applied to narrow or widen the actual pitch used in the design. The increments of change made could be very small, i.e., below that would be normally considered for ground rule changes (˜10 nm, for example). Similarly, where kerf structures monitor the performance of types of via combinations for printability, manufacturing information could indicate that changes in vias are necessary, e.g., slight enlargement or spacing changes, in response to changes in the process. The manufacturing information is fed back and applied to the current layout as manufactured using the above-described selective scaling methodology. As discussed above, the manufacturing information is used to identify scaling targets for problem objects. This yield learning process may be particularly helpful when moving a design to a new, second fabrication facility. The second fabrication facility is likely to have very slightly different “optimum” points for some ground rule values. Over time, these points can be found, and the part numbers optimized to the separate fabrication facilities. III. Conclusion In the previous discussion, it will be understood that the method steps discussed are performed by a processor, such as PU 114 of system 100, executing instructions of program product 122, stored in memory. It is understood that the various devices, modules, mechanisms and systems described herein may be realized in hardware, software, or a combination of hardware and software, and may be compartmentalized other than as shown. They may be implemented by any type of computer system or other apparatus adapted for carrying out the methods described herein. A typical combination of hardware and software could be a general-purpose computer system with a computer program that, when loaded and executed, controls the computer system such that it carries out the methods described herein. Alternatively, a specific use computer, containing specialized hardware for carrying out one or more of the functional tasks of the invention could be utilized. The present invention can also be embedded in a computer program product, which comprises all the features enabling the implementation of the methods and functions described herein, and which—when loaded in a computer system—is able to carry out these methods and functions. Computer program, software program, program, program product, or software, in the present context mean any expression, in any language, code or notation, of a set of instructions intended to cause a system having an information processing capability to perform a particular function either directly or after the following: (a) conversion to another language, code or notation; and/or (b) reproduction in a different material form. While this invention has been described in conjunction with the specific embodiments outlined above, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the embodiments of the invention as set forth above are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the invention as defined in the following claims.

<SOH> BACKGROUND OF THE INVENTION <EOH>1. Technical Field The present invention relates generally to integrated circuit design, and more particularly, to selectively scaling an integrated circuit design layout by: layer, region or cell, or a combination of these, for the purposes of increasing yield in early processes in such a way that hierarchy is preserved. 2. Related Art One way of modifying an existing very large scale integrated (VLSI) circuit design to increase its manufacturing yield is to spread wires and add redundant vias in order to decrease critical area and increase via reliability. However, in the early stages of a new manufacturing process, these post-layout modifications alone may not be sufficient to achieve the desired yield improvement. Another yield-enhancing modification to an existing layout is to relax the spacing and width tolerances, which can be accomplished by a geometric scaling process. A challenge arises, however, when this scaling is attempted on only certain design layers and in the presence of certain other geometric constraints or in the presence of hierarchy. For example, back-end-of-line (BEOL) layers might be chosen for scaling but without altering any device sizes, and with the requirement that the location of connections from the top-level wiring to the integrated-circuit package remain fixed. A simple linear geometric scaling (i.e., multiplying the coordinates of every object in the design database by a fixed scaling factor) is obviously inadequate if connectivity is to be maintained between layers that are scaled and layers that are not scaled. The problem of hierarchical scaling itself is difficult to solve. One approach is addressed in co-pending U.S. patent application Ser. No. 10/438,625 (currently pending), entitled “A Practical Method for Hierarchical-Preserving Layout Optimization of Integrated Circuit Layout,” which is hereby incorporated by reference. Another approach is selective scaling, an example of which is disclosed in U.S. Pat. No. 6,756,242 to Regan. Regan, however, teaches scaling an entire design with different scaling factors in an X direction and a Y direction, which is also inadequate if connectivity is to be maintained between layers. In semiconductor manufacturing, design layouts are completed with a set of fixed ground rules that are provided to the designers by the manufacturing organization. The ground rules describe process and lithography best estimates of what is manufacturable. The ground rules attempt to balance chip density on a wafer (aggressiveness) with what can be reliably manufactured (conservatism). During the lifetime of a technology process or a design, “learning” takes place through failure analysis on finished products and in the manufacturing line. If implemented, this learning can improve yields. For example, the ground rules may change to reflect the yield learning. Unfortunately, frequent or considerable changes cannot usually be made because implementation of any change is expensive because each requires designer involvement in modifying the design to reflect the new ground rules. More significantly, any design modification typically requires new masks, which are extremely expensive. Accordingly, design changes are historically only made very infrequently. Yield related design changes may be added if functional changes require new masks (i.e., if there are difficulties with the function or performance which require a new design iteration), or if there are significant yield issues which force a new design iteration in order to achieve cost targets. Future manufacturing and design environments, however, provide several important aspects that may allow significant improvement of this process: First, maskless lithography has been proposed for future technologies, which if implemented will eliminate the costs of additional mask sets for a changed design. Second, improved simulation and validation capabilities may provide the ability to do more “full-up” simulations of designs because of improved algorithms, parallel processing, and system architectures. In this fashion, selective scaling may be applied in a tightly coupled feedback loop with the manufacturing line with process and yield feedback, during the life of a design. In current manufacturing and design environments, limited mask lifespans offer the opportunity for periodic layout updates during the life of a design. In view of the foregoing, there is a need in the art to address the problems of the related art.

<SOH> SUMMARY OF THE INVENTION <EOH>The invention includes methods, systems and program products for selectively scaling an integrated circuit (IC) design by: layer, region or cell, or a combination of these. The selective scaling technique can be applied in a feedback loop with the manufacturing system with process and yield feedback, during the life of a design, to increase yield in early processes in such a way that hierarchy is preserved. The invention removes the need to involve designers in improving yield. A first aspect of the invention is directed to a method for selectively scaling an integrated circuit design layout, the method comprising the steps of: identifying a scaling target for at least one problem object of the design layout based on manufacturing information; defining technology ground rules and methodology constraints for each problem object; determining a scaling factor for each problem object; determining which at least one of a plurality of scaling techniques is to be applied to each problem object, and scaling each problem object with a respective at least one scaling technique and scaling factor; and in the case that assembly is required, performing placement and routing to assemble the design using the scaled problem object. A second aspect is directed to a system for selectively scaling an integrated circuit design layout, the system comprising the steps of: means for identifying a scaling target for at least one problem object of the design layout based on manufacturing information; means for defining technology ground rules and methodology constraints for each problem object; means for determining a scaling factor for each problem object; means for determining which at least one of a plurality of scaling techniques is to be applied to each problem object, and scaling each problem object with a respective at least one scaling technique and scaling factor; and means for, in the case that assembly is required, performing placement and routing to assemble the design using the scaled problem object. A third aspect is directed to a computer program product comprising a computer useable medium having computer readable program code embodied therein for selectively scaling an integrated circuit design layout, the program product comprising: program code configured to identify a scaling target for at least one problem object of the design layout based on manufacturing information; program code configured to define technology ground rules and methodology constraints for each problem object; program code configured to determine a scaling factor for each problem object; program code configured to determine which at least one of a plurality of scaling techniques is to be applied to each problem object, and scaling each problem object with a respective at least one scaling technique and scaling factor; and program code configured to, in the case that assembly is required, perform placement and routing to assemble the design using the scaled problem object. A fourth aspect is directed to a method for improving yield of an integrated circuit design layout during manufacturing, the method comprising the steps of: testing a manufactured design layout and identifying at least one problem object that is a problem; generating a scaling target for each problem object based on manufacturing information obtained during the testing; and feeding back the manufacturing information to a system for selective scaling of the design layout to improve yield using a scaling target for at least one problem object of the design layout based on the manufacturing information. A fifth aspect of the invention is directed to a system for improving yield of an integrated circuit design layout during manufacturing, the system comprising: means for testing a manufactured design layout and identifying at least one problem object that is a problem; means for generating manufacturing information including a scaling target for each problem object; and means for feeding back the manufacturing information to a system for selective scaling of the design layout to improve yield using a scaling target for at least one problem object of the design layout based on the manufacturing information. A sixth aspect of the invention is directed to a computer program product comprising a computer useable medium having computer readable program code embodied therein for improving yield of an integrated circuit design layout during manufacturing, the program product comprising: program code configured to test a manufactured design layout and identifying at least one problem object that is a problem; program code configured to generate manufacturing information including a scaling target for each problem object; and program code configured to feedback the manufacturing information to a system for selective scaling of the design layout to improve yield using a scaling target for at least one problem object of the design layout based on the manufacturing information. The foregoing and other features of the invention will be apparent from the following more particular description of embodiments of the invention.

20041015

20080422

20060420

82899.0

G06F1750

KIK, PHALLAKA

INTEGRATED CIRCUIT SELECTIVE SCALING

UNDISCOUNTED

ACCEPTED

G06F

ACCEPTED

IMPROVED CRATE SYSTEM

A crate system for transport of items. The system includes a set of U shaped tubes that are mounted in an upright position on beams. A second set of U shaped tubes are also mounted in an upright position on beams. Each assembled set are then mounted on top of one another to form a crate system. The crate system can safely secure and even stack heavy items on top of one another. These crate systems can then be disassembled for packing and shipping back to the original shipper.

1. A crate system for transporting items wherein said crate system comprises: a first set of structural tubes; a first set of beams; and a first fastening mechanism for securing said first set of structural tubes in a spaced relationship to one another to said first set of beams. 2. The crate system of claim 1 wherein said crate system further includes: a second set of structural tubes; a second set of beams; a second fastening mechanism for securing said second set of structural tubes in a spaced relationship to one another to said second set of beams; and a securing mechanism for securing said assembled first set of structural tubes to said assembled second set of structural tubes. 3. The crate system of claim 1 wherein said first set of structural tubes includes: each of said first set of structural tubes shaped in a substantially U shape. 4. The crate system of claim 1 wherein said first set of structural tubes includes: each of said first set of structural tubes shaped in a substantially U shape; and said first set of beams include a open slot. 5. The crate system of claim 1 wherein said first set of structural tubes includes: each of said first set of structural tubes shaped in a substantially U shape; said first set of beams include a open slot; and said first fastening mechanism includes spring nuts mounted in said open slot and a threaded fastener engaging through each of said first set of structural tubes into said spring nuts. 6. The crate system of claim 1 wherein said first set of structural tubes includes: each of said first set of structural tubes shaped in a substantially U shape; and said fastening mechanism secures said first set of structural tubes in a substantially upright position spaced from each other on said first set of beams. 7. The crate system of claim 1 wherein said crate system further includes: a second set of structural tubes; a second set of beams; a second fastening mechanism for securing said second set of structural tubes in a spaced relationship to one another to said second set of beams; and a securing mechanism for securing said assembled first set of structural tubes to said assembled second set of structural tubes wherein said securing mechanism includes at least one beam extending the length of said crate and fasteners securing said assembled first set of structural tubes to said assembled second set of structural tubes. 8. The crate system of claim 1 wherein said crate system further includes: each of said first set of structural tubes shaped in a substantially U shape; said fastening mechanism secures said first set of structural tubes in a substantially upright position spaced from each other on said first set of beams; a second set of structural tubes shaped in a substantially U shape; a second set of beams; a second fastening mechanism for securing said second set of structural tubes in a substantially upright position in spaced relationship to one another to said second set of beams; and a securing mechanism for securing said assembled first set of structural tubes to said assembled second set of structural tubes. 9. The crate system of claim 1 wherein said crate system further includes: each of said first set of structural tubes shaped in a substantially U shape; said fastening mechanism secures said first set of structural tubes in a substantially upright position spaced from each other on said first set of beams; a second set of structural tubes shaped in a substantially U shape; a second set of beams; a second fastening mechanism for securing said second set of structural tubes in a substantially upright position in spaced relationship to one another to said second set of beams; and a securing mechanism for securing said assembled first set of structural tubes to said assembled second set of structural tubes wherein said securing mechanism includes at least one beam extending the length of said crate and fasteners securing said assembled first set of structural tubes to said assembled second set of structural tubes. 10. A method for using a crate system for transporting items wherein said method comprises: providing a first set of structural tubes; providing a first set of beams; providing a first fastening mechanism; and securing said first set of structural tubes in a spaced relationship to one another to said first set of beams by said first fastening mechanism. 11. The method of claim 10 wherein said method further includes the steps of: providing a second set of structural tubes; providing a second set of beams; providing a second fastening mechanism; securing said second set of structural tubes in a spaced relationship to one another to said second set of beams with said second fastening mechanism; providing a securing mechanism; and securing said assembled first set of structural tubes to said assembled second set of structural tubes with said securing mechanism. 12. The method of claim 10 wherein said step of providing said first set of structural tubes includes: providing each of said first set of structural tubes shaped in a substantially U shape. 13. The method of claim 10 wherein said method further includes: said step of providing said first set of structural tubes includes providing each of said first set of structural tubes shaped in a substantially U shape; and providing an open slot on said first set of beams. 14. The method of claim 10 wherein said method further includes: said step of providing said first set of structural tubes includes shaping each of said first set of structural tubes in a substantially U shape; said step of providing said first set of beams includes providing an open slot; and proving spring nuts on said first fastening mechanism mounted in said open slot and a threaded fastener engaging through each of said first set of structural tubes into said spring nuts. 15. The method of claim 10 wherein said method further includes: said step of providing said first set of structural tubes includes shaping each of said first set of structural tubes in a substantially U shape; and said step of securing said first set of structural tubes to said first beams includes securing said first set of structural tubes in a substantially upright position spaced from each other on said first set of beams. 16. The method of claim 10 wherein said method further includes: providing a second set of structural tubes; providing a second set of beams; providing a second fastening mechanism; securing said second set of structural tubes in a spaced relationship to one another to said second set of beams with said second fastening mechanism; providing a securing mechanism; and securing said assembled first set of structural tubes to said assembled second set of structural tubes wherein said securing mechanism includes at least one beam extending the length of said crate and fasteners securing said assembled first set of structural tubes to said assembled second set of structural tubes with said securing mechanism. 17. The method of claim 10 wherein said method further includes: shaping each of said first set of structural tubes in a substantially U shape; securing said first set of structural tubes in a substantially upright position spaced from each other on said first set of beams with said first fastening mechanism; providing a second set of structural tubes shaped in a substantially U shape; providing a second set of beams; providing a second fastening mechanism; securing said second set of structural tubes in a substantially upright position in spaced relationship to one another to said second set of beams with said second fastening mechanism; providing a securing mechanism; and securing said assembled first set of structural tubes to said assembled second set of structural tubes with said securing mechanism. 18. The method of claim 10 wherein said method further includes: shaping each of said first set of structural tubes in a substantially U shape; securing said first set of structural tubes in a substantially upright position spaced from each other on said first set of beams with said first fastening mechanism; providing a second set of structural tubes shaped in a substantially U shape; providing a second set of beams; providing a second fastening mechanism; securing said second set of structural tubes in a substantially upright position in spaced relationship to one another to said second set of beams with said second fastening mechanism; providing a securing mechanism; and securing said assembled first set of structural tubes to said assembled second set of structural tubes with said securing mechanism wherein said securing mechanism includes at least one beam extending the length of said crate and fasteners securing said assembled first set of structural tubes to said assembled second set of structural tubes. 19. The method of claim 10 wherein said method further includes: disassembling said crate by unfastening said first set of structural tubes from said first set of beams. 20. The method of claim 19 wherein said method further includes: packaging said unassembled first set of structural tubes and said unassembled said first set of beams and said fastening mechanism for shipment.

BACKGROUND OF THE INVENTION Field of the Invention This invention relates to the field of shipping crates for large items. Most manufactured items are packaged for shipment to their destination. This packaging may range from simple plastic and cardboard packaging for small consumer items to large wooden crates or containers for larger items. The larger crates can be quite cumbersome and complex in order to properly prevent damage to their contents. Often those crates are subject to mishandling and damage due to the use of equipment to manipulate them. Also, the crates and their contents must often be stacked on top of one another to provide for an efficient shipment. These problems are particularly prevalent in the shipment of larger items such as snowmobiles, personal water craft or all terrain vehicles “ATVs” as well as other large items. These items tend to be large, bulky and heavy as well as susceptible to damage. The weight alone makes it difficult to stack these items without special precautions. The weight and bulk of these types of items render fiberboard, cardboard or plastic impractical for use in shipment. Presently, these items are shipped in specially prepared wooden crates. A typical wooden crate consists of a framework of two by fours, cross-bracing timbers, and plywood panel sides. These wooden crates present a multitude of problems. The crates are relatively expensive to manufacture and to assemble. Once the items have been packed within the crates, it is difficult to inspect the items for customs, or for damage. The crates must be disassembled which typically damages the crate. Wooden crates also are environmentally unsound, both from the viewpoint of the destruction of forest environment to create the raw materials, the disposal of the crates once they are discarded and from their inability to withstand environmental forces. The crates become weakened and damaged from rain, snow, ice and other environmental forces which can lead to damage to their contents. Certain countries, locales and companies will not accept shipments in wooden containers due to problems with insects and disease that may be carried in the wooden containers. The disposal of the wooden crates is a major factor. The wooden components are normally discarded after use due to the damage suffered during shipment and unpacking. This creates additional cost in disposing of the disassembled components. Even if the components are reusable, the storage of those bulky components is costly. SUMMARY OF THE INVENTION The present invention provides an improved crate system that solves these and other problems. The crate system of the present system provides a lightweight crate system that is extremely strong yet is reusable. The crate system can also be disassembled for shipment or for compact storage. The crate system of a preferred embodiment of the present invention includes a set of lightweight high strength structural tubes. These structural tubes are secured to beams to form the crate. The structural tubes can be fabricated in a substantially rectangular shape, or in another preferred embodiment, be fabricated in a substantially U shape. In the latter embodiment, the system can be assembled into lower and upper shells that are secured together to form a substantially rectangular shape. Other shapes can be formed by simply fabricating the structural tubes into a desired shape. In a preferred embodiment of the present invention, the crate system is formed from structural tubing. The structural tubing can be hollow lightweight high strength steel tubing, such as one-half to one-inch tubing. Other sizes can be used as well as other material choices. The crate system of a preferred embodiment may also incorporate beams, slats, open slot C channel members or other elongated members. This provides a high strength support structure to reinforce the structural tubes as well as to maintain the structural tubing in the desired spaced relationship to one another. The open slot C channel members also allow the fastening mechanisms for securing the structural tubes to the beams to be easily adjusted to the appropriate locations. In one preferred embodiment, the fastening mechanisms include spring nuts that are easily inserted into the channel members. In the crate system of the preferred embodiment using an upper shell and a lower shell, beams are secured along the upper ends of the structural tubes to form a mechanism for securing the upper shell to the lower shell. The beams are secured by fasteners, such as dowel pins, spring loaded star nuts or simply by welding nuts to the upper ends. The improved crate system of a preferred embodiment can be easily and quickly assembled with little skill necessary and only one wrench. The structural tubes are secured to the beams by a simple fastening system that aligns the structural tubes in the appropriate spacing. If the upper shell and lower shell system is used, those are easily secured together. The item can then be placed in the system either before or after the shells are fastened together. It can be shrink wrapped to allow viewing of the item for inspection or simply covered with cardboard or fiberboard. The crates can be safely stacked on top of one another without fear of damage to the crate or its contents. Once the item is unpacked, the crate system can be partially disassembled to allow compact storage or completely disassembled for packing the components for return or for storage. The crate system can be reused numerous times or reused for other structures. The cost of shipping the crate system components is less than the current cost of disposing of wooden crate materials and certainly less than the cost of constructing a similar size of wooden crates. The crate system can be easily scaled to ship most items, and has particular use for large items, such as all terrain vehicles, personal watercraft, snowmobiles, generators or other large items. These and other features will be evident from the ensuing detailed description of preferred embodiments and from the drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates the assembled crate system of a preferred embodiment of the present invention. FIG. 2 illustrates a side view of the crate system of FIG. 1 with an all terrain vehicle packed inside of it. FIG. 3 illustrates the components of the crate system of FIG. 1. FIG. 4 illustrates a partially assembled lower shell of the crate system of FIG. 1. FIG. 5 illustrates an exploded view of the spring nut fastening system used in the embodiment of FIG. 1. FIG. 6 illustrates a detail view of the assembled spring nut fastening system used in thee embodiment of FIG. 1. FIG. 7 illustrates an end view of a partial assembly of the embodiment of FIG. 1. FIG. 8 illustrates a preferred fastening system used in the embodiment of FIG. 1. FIG. 9 illustrates an alternative fastening system. FIG. 10 illustrates another alternative fastening system. FIG. 11 illustrates a securing system used in the preferred embodiment of FIG. 1. FIG. 12 illustrates a collapsed section of the crate system of the embodiment of FIG. 1. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The present invention, in a preferred embodiment, provides an improved shipping crate system for large items. A preferred embodiment of the present invention is described below. It is to be expressly understood that this descriptive embodiment is provided for explanatory purposes only, and is not meant to unduly limit the scope of the present invention as set forth in the claims. Other embodiments of the present invention are considered to be within the scope of the claimed inventions, including not only those embodiments that would be within the scope of one skilled in the art, but also as encompassed in technology developed in the future. A preferred embodiment of an improved shipping crate system of the present invention is illustrated in FIGS. 1-12. This preferred embodiment is described for use in shipping ATVs, snowmobiles, personal watercraft and other related items but it is expressly noted that other items may be used with the present invention. Also, the shipping crate system of the present invention may also be scaled down or up in size as desired for shipment of other items. The preferred embodiment of the shipping crate system 10 includes spaced lower tubes 20 and upper tubes 30. In this preferred embodiment, the tubes 20 and 30 are fabricated from standard hollow steel tubing, preferably one-half inch to one inch square tubing. It is to be expressly understood that other sizes of tubing, types of tubing, such as C or U shaped tubing and even materials, such as high strength plastic can be used as well. The tubes 20 and 30 are fabricated into a U shape, as shown in the FIGS. 1-12. In this preferred embodiment, all of the lower tubes and upper tubes are identical to one another. It is to be understood that in other embodiments, the tubes may be of different sizes, strengths or shapes from one another. However, it in this embodiment, the tubes are all identical to provide efficient manufacturing, inventory and assembly. Beams 40, 42, 44, 46, 48, 50, 52, 54 are integral to the crate 10. The beams provide the dual purpose of reinforcing the strength of the crate as well as to secure the tubes 20, 30 into an integral structure. The beams in this preferred embodiment are formed in a channel having an internal slot 56 with overextending lips 58, 60. It is to be expressly understood that other types of beams may be used as well, such as tubing, other types of beams, slats or any other suitable member. The lower tubes 20 are assembled as shown in FIG. 4. The tubes are mounted in an upright position on beams 40, 42 and spaced from one another. The tubes 20 include pre-drilled holes 22, 24 that are oriented directly over the channels 40, 42 that are spaced from one another in a parallel fashion. The tubes are then fastened to the channels 40, 42 by inserting spring nut 62 into the channel slot 56 as shown in FIGS. 5 and 6. The spring nut 62 includes a grooved upper surface 64, 66 that engages in the lips 58, 60. This engagement is secured by spring 68 that allows the nut 62 may be moved along the channel slot 56 as necessary. Bolt 70 engages through the pre-drilled hole in the tube 20 and engage spring nut 62 to secure the tube 20 to channel 40. Each of the tubes 20 are loosely secured onto the beams 40, 42 initially. Once each of the tubes 20 have been loosely secured onto the beams, then surface beams 44, 46 are mounted to the upper surfaces 24, 26 as shown in FIGS. 3 and 6. The beams 44, 46 include a plurality of spaced pre-drilled holes. A fastening mechanism 80 is mounted in the upper end of each of the tubes 20. One example is fastening mechanism illustrated in FIG. 8 that includes a dowel pin 82. This dowel pin includes a threaded aperture 84. Another example is the fastening mechanism 86 is shown in FIG. 9. This fastening mechanism 86 includes a plate with a threaded aperture or nut on the upper end of the tube 20. Another example is fastening mechanism 90 shown in FIG. 10. This fastening mechanism 90 includes a plurality of spring loaded plates 92 surrounding threaded bushing 94. The spring loaded plates 92 engage against the inner surfaces of the tubes 20 as the bushing is pulled forward. In each of these and other fastening mechanisms, bolts are inserted into the channel slot of the beams 44, 46 and into the pre-drilled holes to engage the fastening mechanism 82. Once the beams 44, 46 have been securely tightened onto the upper ends of the tubes 20, then the fasteners 70 and spring nuts 62 are securely tightened. This creates a secure and rigid lower shell for the crate 10. The upper shell is created in an identical fashion using tubes 30 and beams 48, 50 and surface beams 52, 54. Once the upper shell has been assembled, then the entire crate can be assembled, as shown in FIGS. 7 and 11. The upper shell is inverted and set down onto the lower shell so that the surface beams 44, 46 of the lower shell mate against the surface beams 52, 54 of the upper shell. In the preferred embodiment as shown in FIG. 10, a wooden, plastic, metal or other material slat 96 is inserted to engage in both of the slots 56 of the surface beams 44, 46, 52, 54 respectively. This slat maintains the alignment of the lower shell and the lower shell during assembly and during use. A bolt and nut assembly 100,102 are then used to secure the upper shell and the lower shell together. The assembled crate is shown in FIGS. 1 and 2. In the preferred embodiment, the crate 10 is scaled particularly for use in the shipment of all terrain vehicles (“ATV”), snowmobiles, personal watercraft or other larger, heavier items. This enables the crate to be strong, rigid but also relatively light compared with wooden crates that have been previously used. The tubes 20 can also be selectively reinforced at key locations if that is necessary as well by adding additional tubes at that location. The crates can be safely stacked onto one another even when fully loaded. Also, the crates can be easily inspected. The crates may be left open, but more preferably are either shrink wrapped or covered with cardboard. Once the crate has been transported or is otherwise ready for the item to be removed, the crate is easily opened. The crate will have suffered no or minimal damage so it can be immediately and safely reused. However, if the crate is not needed, it can be quickly and compactly disassembled. The crate can be disassembled by removing the fastening assemblies 100 so the upper shell can be separated from the lower shell. Then the fastening mechanism 80 can be removed so the surface beams 44, 46 and 52, 54 can be removed from the tubes 20 and 30 respectively. The fasteners 70 can be loosened to allow the tubes 20, 30 to simply collapsed as shown in FIG. 1 3 to allow the storage of the crate 10. Another alternative is to remove the fasteners to allow the tubes 20, 30 and beams 40-54 to be packed into a relatively compact shipment to be returned to the original destination. Other embodiments of the crate system of the present invention are considered to be within the scope of the claimed invention. The crate 10 can be scaled to create any size of crate by changing the size and or number of tubes 20, 30 and beams. Also, different material choices may be used as well depending on the weight and size of the item(s) to be shipped as well as the cost efficiencies desired. Another preferred embodiment of the present invention utilizes only the lower shell as described above. Items are packed within the lower shell and then covered by either a top or simply by shrink wrapping. Another preferred embodiment uses rectangular or oval shaped tubes instead of the U shaped tubes with a lower and upper shell structure. The crate system of this embodiment is assembled with the beams without the need of the surface beams that were necessary to secure the lower shell and upper shell. Other configurations may be used as well to perform the function of the presently claimed invention. These and other features of the present invention are considered to be within the scope of the claimed inventions.

<SOH> BACKGROUND OF THE INVENTION <EOH>

<SOH> SUMMARY OF THE INVENTION <EOH>The present invention provides an improved crate system that solves these and other problems. The crate system of the present system provides a lightweight crate system that is extremely strong yet is reusable. The crate system can also be disassembled for shipment or for compact storage. The crate system of a preferred embodiment of the present invention includes a set of lightweight high strength structural tubes. These structural tubes are secured to beams to form the crate. The structural tubes can be fabricated in a substantially rectangular shape, or in another preferred embodiment, be fabricated in a substantially U shape. In the latter embodiment, the system can be assembled into lower and upper shells that are secured together to form a substantially rectangular shape. Other shapes can be formed by simply fabricating the structural tubes into a desired shape. In a preferred embodiment of the present invention, the crate system is formed from structural tubing. The structural tubing can be hollow lightweight high strength steel tubing, such as one-half to one-inch tubing. Other sizes can be used as well as other material choices. The crate system of a preferred embodiment may also incorporate beams, slats, open slot C channel members or other elongated members. This provides a high strength support structure to reinforce the structural tubes as well as to maintain the structural tubing in the desired spaced relationship to one another. The open slot C channel members also allow the fastening mechanisms for securing the structural tubes to the beams to be easily adjusted to the appropriate locations. In one preferred embodiment, the fastening mechanisms include spring nuts that are easily inserted into the channel members. In the crate system of the preferred embodiment using an upper shell and a lower shell, beams are secured along the upper ends of the structural tubes to form a mechanism for securing the upper shell to the lower shell. The beams are secured by fasteners, such as dowel pins, spring loaded star nuts or simply by welding nuts to the upper ends. The improved crate system of a preferred embodiment can be easily and quickly assembled with little skill necessary and only one wrench. The structural tubes are secured to the beams by a simple fastening system that aligns the structural tubes in the appropriate spacing. If the upper shell and lower shell system is used, those are easily secured together. The item can then be placed in the system either before or after the shells are fastened together. It can be shrink wrapped to allow viewing of the item for inspection or simply covered with cardboard or fiberboard. The crates can be safely stacked on top of one another without fear of damage to the crate or its contents. Once the item is unpacked, the crate system can be partially disassembled to allow compact storage or completely disassembled for packing the components for return or for storage. The crate system can be reused numerous times or reused for other structures. The cost of shipping the crate system components is less than the current cost of disposing of wooden crate materials and certainly less than the cost of constructing a similar size of wooden crates. The crate system can be easily scaled to ship most items, and has particular use for large items, such as all terrain vehicles, personal watercraft, snowmobiles, generators or other large items. These and other features will be evident from the ensuing detailed description of preferred embodiments and from the drawings.

20041015

20111220

20060420

98500.0

B65D616

GROSSO, HARRY A

IMPROVED CRATE SYSTEM

SMALL

ACCEPTED

B65D

ACCEPTED

Built-in jitter measurement circuit for voltage controlled oscillator and phase locked loop

A built-in jitter measurement circuit for a VCO (voltage-controlled oscillator) and a PLL (phase-locked loop) is disclosed. The circuit includes a divider for dividing frequency of a signal, a time to digital converter (TDC) for converting the period of the divided signal into digital values, a variance calculator for calculating variance of the period of the divided signal, a mean calculator for calculating mean value of the period of the divided signal, a encoder and counter for encoding and calculating the period of the divided signal, and a state controller as a controller for all other components. The circuit disclosed utilizes output clock of an opened-loop circuit to be measured and a divider for increasing jitter of the original signal. By measuring the bandwidth of a closed-loop circuit, accordingly, jitter of output clock of an opened-loop or an closed-loop circuit is measured by correlating the measured bandwidth and the jitter values from extrapolation.

1. A built-in jitter measurement circuit for a voltage-controlled oscillator (VCO) and a phase-locked loop (PLL) comprising: a divider for dividing frequency of a signal to be measured by n; a state controller as a controller for other components; a variance calculator for calculating variance of the signal to be measured; a mean calculator for calculating mean of the signal to be measured; a time to digital converter (TDC) for converting the period of the signal to be measured into digital values; and a encoder and counter for counting and encoding the digital values output from TDC; wherein, the divider divides the frequency of the signal to be measured, the period of the divided signals to be measured are converted into digital values by TDC, encoder and counter, the digital values are calculated by the variance calculator and the mean calculator, and period means and jitter of the divided signal are determined. 2. The circuit of claim 1, wherein after the period mean and the jitter of the divided signal are determined, the circuit further comprises a step of performing calculation according to the equation as following: Y′={y1+e1,y1,y2+e2,y3+e3, . . . } MY′=nMX+ME σ2Y′=nσ2X+σ2E, for determining the period jitter of the original signal (σx). 3. The circuit of claim 1, wherein the TDC further comprises a latch chain, a counter, an encoder and a set of flip-flops. 4. The circuit of claim 3, wherein the TDC performs operating modes of HOLD, RUN and CLEAR in a single synchronous cycle. 5. The circuit of claim 3, wherein the encoder uses equalization encoding for linearizing the output of the TDC and balancing the difference between rising-time and falling-time of the signal in a standard cell in the latch chains so that enhance measurement precision. 6. The circuit of claim 3, wherein the circuit further comprises a multiplexer and a set of D flip-flops for correcting random output of latch chain and increasing fault coverage.

FIELD OF THE INVENTION This invention relates to a built-in jitter measurement circuit for a voltage-controlled oscillator (VCO) and a phase-locked loop (PLL), wherein a divider is utilized for outputting the increasing jitter of the signal to be measured such that the jitter of the original un-divided signal is determined by some derivations. BACKGROUND OF THE INVENTION A voltage-controlled oscillator (VCO) and a phase-locked loop (PLL) are commonly used components in many circuit designs. Jitter of the output clock signal in a VCO or a PLL determine the quality even the performance of the output signal. Therefore jitter measurement in a VCO and a PLL becomes indispensable in the field of circuit design. As a result of the rapid advancement of VLSI technology, Frequently, a SoC (System on A Chip) has an embedded PLL. However, there are many restrictions posed when external measuring equipment measures a built-in PLL. Such restrictions include noise from measuring environment and package pins, bandwidth limitation of the external measuring equipment and lack of input and output interface for built-in PLL to external. Compare with prior art methods measuring by external equipment, an internal measuring circuit has advantages such as low cost, faster measuring, better precision, less restriction on measuring capacity, and ability to perform at-speed testing. Jitter is often less than several hundred pico seconds in many cases. Conventionally, internal measurement technologies are usually implemented by analog designs, which are complicated and expensive. LogicVision Inc. utilizes components including delay-lines for adjusting delays, flip-flops and counters for counting timing intervals, and then combining with statistics method for calculating jitter. Nonetheless, its precision and accuracy are limited to the resolution of the delay-lines and the setup time of the flip-flops. Credence utilizes built-in clock generators for generating clocks of predefined periods. A signal to be measured is used for triggering the generated clocks. First cycle trigger the first generated clock and second cycle trigger the second generated clock. After the phase of the first generated clock matches the phase of the second generated clock, the period of the signal to be measured is determined by the number of cycles required for phase matching. By measuring the periods of the signal repeatedly, the jitter of the signal is determined combined with statistics method. The internal clock generators and matching decision devices used in such method restrict precision and accuracy of jitter measurement. Such method also requires extra device for performing statistics calculation and results in larger circuit area. Precision level of jitter measurement taken by aforementioned methods only reaches several hundred pico seconds. Antonio H. Chan and Gordon W. Roberts proposed a paper titled “A Synthesizable, Fast and High-resolution Timing Measurement Device Using a Component-invariant Vernier Delay Line” in the International Test Conference, 2001. Chan and Roberts applied a differential method for overcoming the precision restriction caused by minimum delay of a component. However, the extra design cost grows exponentially with improved precision, also, the differential values of components will shift when implemented in different manufacturing process and result in undetermined precision and undesirable accuracy. SUMMARY OF THE INVENTION The present invention provides a built-in jitter measurement circuit for a voltage-controlled oscillator (VCO) and a phase-locked loop (PLL) in a SoC for eliminating the need of external high-end tester, the interference from noise of environment, noise of output and input pins in measurement. The main objective of the present invention is to provide a built-in jitter measurement circuit, wherein period jitter and long-term jitter are determined by statistics calculation performed by the circuit and as a result eliminating the needs for massive data output and a process for complicated statistical analysis of the data. Another objective of the present invention is to provide a built-in jitter measurement circuit, wherein a test integration method and a test subtraction method are applied for increasing precision and accuracy of jitter measurement. Another objective of the present invention is to provide a built-in jitter measurement circuit, wherein an all digital standard cell-based design is adapted for increasing reliability and noise immunity. Such design avoids difficulties faced in analog designed and is suited for different manufacturing processes. Another objective of the present invention is to provide a built-in jitter measurement circuit, wherein the measurement circuit is embedded with DfT (Design for Test) for ensuring the test quality. Another objective of the present invention is to provide a built-in jitter measurement circuit, wherein the circuit is applicable to a core-based self test circuit in a SoC. Another objective of the present invention is to provide a built-in jitter measurement circuit, wherein measuring the divided and jitter increased signal of the output clock of the opened-loop circuit and accordingly long-term jitter of the output clock of the opened-loop circuit can be determined. Another objective of the present invention is to provide a built-in jitter measurement circuit, wherein jitter measured from several measurements are calculated by extrapolation for recovering the period jitter and eliminating the error caused in measurement. Another objective of the present invention is to provide a built-in jitter measurement circuit, by measuring the bandwidth of a closed-loop circuit, accordingly, jitter of output clock of the closed-loop, which is jitter defined in a PLL, is measured by correlating the measured bandwidth and the jitter from extrapolation. Another objective of the present invention is to provide a built-in jitter measurement circuit, wherein TDC comprising latch chain is adapted for measuring periods. The present invention is characterized by being able to perform operating modes of HOLD, CLEAR and RUN in the same cycle, and a fact that values represented by digital output are in proportion to the time of the periods. Another objective of the present invention is to provide a built-in jitter measurement circuit, where the circuit performs statistical calculation. The outputs of the TDC and the square of the outputs are added up for determining the jitter of the signal. Another objective of the present invention is to provide a built-in jitter measurement circuit, equalization encoding is applied for linearizing the output of the TDC and balancing the difference between rising-time and falling-time of the signal in a standard cell in the latch chains so that measurement errors are reduced and enhancing the precision. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a Gaussian distribution diagram of periodical signal jitter; FIG. 2 is a curve diagram illustrating measurement of an opened-loop and a closed-loop jitter; FIG. 3 is a diagram illustrating waveform correlation between signal to be measured x(t) and divided signal to be measured y(t); FIG. 4a is a schematic curve diagram illustrating the jitter measurement method used according to the present invention; FIG. 4b is a curve diagram illustrating frequency response of a PLL; FIG. 5 is a design block diagram illustrating the jitter measurement circuit; FIG. 6a is a design block diagram illustrating a time to digital converter (TDC); FIG. 6b is a design block diagram illustrating a test circuit having multiplexers and D flip-flops; FIG. 7 is a timing diagram illustrating the TDC; FIG. 8 is a data diagram illustrating comparison between linear encoding and equalization encoding; FIG. 9 is a data diagram illustrating simulation results of different input periods; FIG. 10 is data diagram illustrating simulation results of different divided settings; and FIG. 11 is a data diagram illustrating simulation results of different input jitter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (I) Jitter Measurement Scheme FIG. 1 describes a Gaussian distribution of jitter for periodical signal, where t is a random variable of signal's period, p(t) is a probability density and σx is the standard deviation. FIG. 2 describes measurement results of long-term jitter of an opened-loop and a closed-loop circuits, where T is time, σL(T) is a long-term jitter for T, κ is a constant coefficient, and τL is the loop bandwidth of a closed-loop circuit. For an opened-loop signal, if its period is T and period jitter is σP, then the n-periods long-term jitter for it is σL(nT)={square root}{square root over (n)}*σP. However, the long-term jitter for a closed-loop circuit is expected to be stabilized as σ L ⁡ ( τ L ) = τ L T * σ P when the measurement time is longer than τL. Such stabilized long-term jitter measurement of a closed-loop circuit is considered as the jitter measurement of a PLL. Based on the conclusions above, as shown in the FIG. 3, if a periodic signal to be measured is x(t), period of each cycle is x1, x2, x3 . . . , signal divided by n is y(t), each period set is y1, y2, y3 . . . , and then equations are described as follows: y1=x1+x2+ . . . +xn y2=xn+1+xn+2+ . . . +x2n . . . yk=x(k−1)n+1+x(k−1)n+2+ . . . +xkn . . . Also, new random variables are defined as follows: S1={x1, xn+1, x2n+1, . . . } S2={x2, xn+2, x2n+2, . . . } S3={x3, xn+3, x2n+3, . . . } . . . Y={y1, y2, y3, . . . } As a result, Y=S1+S2+S3+ . . . +Sn. Because Sk (k=1,2, . . . ,n) are random variables independent of each other for a opened-loop PLL or VCO, therefore equations are described as follows: MY=MS1+MS2+ . . . +MSn σ2Y=σ2S1+σ2S2+ . . . +σ2Sn For random variables, Ms1=Ms2= . . . =Msn=MX and σs1=σs2= . . . =σsn=σX, accordingly the equation is reduced to: MY=nMX σ2Y=nσ2X The jitter of the signal to be measured x(t) is too low to be accurately measured. On the other hand, the jitter of the signal to be measured y(t) is not. So by measuring the jitter of the signal divided by n, y(t), long-term jitter of signal x(t) with n times period is attained. Also, it follows that the period jitter (σX) of x(t) can also be attained. In addition, If there are errors caused by frequency divider or other factors, a new random variable E={e1, e2, e3, . . . } is defined to represent the errors. Accordingly, equations are represented as follows: Y′={y1+e1, y2+e2, y3+e3, . . . } MY′=nMX+ME (EQU-1) σ2Y′=nσ2X+σ2E According to the equations, calibration can be performed as long as measurement data by setting different n is provided. Thus errors are corrected and measurement accuracy is enhanced. In other words, the long-term jitter of the original signal can be attained by measuring the period jitter of the signal having frequency divided according to the conclusion reached above. As J1, J2, J3 and the curve linked in between shown in FIG. 4a, opened-loop curve is attained after measurement errors are calibrated by setting different n and extrapolation is conducted. Then as shown in the FIG. 4b, τL is the inverse of the measurement of the bandwidth of the PLL when input frequency is set in increments. Apply the τL in the FIG. 4a. The jitter of PLL JPLL (short for stabilized value of long-term jitter of a closed-loop PLL) is thus attained at the intersection of opened-loop curve and the τL curve. (II) An Implementation of Embedded Jitter Measurement Circuit An embedded jitter measurement circuit is described as the following. The circuit is provided for measuring signal after frequency dividing and is based on the equations as follows: M y = ∑ i = 1 N ⁢ y i / N σ y 2 = ( ∑ i = 1 N ⁢ y i 2 / N ) - M y 2 The divisor N in the equations above can be set as 27=128 to reduce the hardware area. As shown in FIG. 5, a block diagram of the embedded circuit is described which includes a 1/n Divider 1, a state controller 2, a variance calculator 3, a mean calculator 4, a encoder and counter 5, and a time to digital converter (TDC) 6. The circuit operates as following steps. The divider 1 divides an input signal and outputs a signal, which is easier to be measured than the original signal. The period of the divided signal is converted into digital values by TDC 6, encoder and counter 5. The digital values are put into calculation by the variance calculator 3 and the mean calculator 4 for calculating the mean of period and jitter value of the divided signal. The jitter value calculated represents the long-term jitter of the original signal with a period of n times. In addition, because the n can be sets to different values, an equation 11 can be applied for calculating the period jitter of the original signal. The design of the TDC 6 is shown in the FIG. 6a. The TDC 6 includes a latch chain 61, a counter 62, an encoder 63 and a set of D flip-flops 64. Digital output values represent the time when the input signal during high level. By appropriate timing setting, the TDC performs operating modes of HOLD, RUN and CLEAR in a single synchronous cycle according to the present invention. When signal enable goes to low level, the latch chain 61 stop to transmit signal, the operating mode is in HOLD mode. When the signal enable goes to high level and the reset signal goes to low level, the signal will be inversed at a NOR-gate and circulate in the latch chain 61, the operating mode is in RUN mode. When the signal enable goes to high level and the reset signal goes to high level, the latch chain continues to circulate digital value zero until the whole loop is stored with digital value zero, the operation mode is in CLEAR mode. Because rise delay time and the fall delay time may not be the same in the latch chain 61, equalization encoding is used in the present invention for enabling a linear curve between the TDC output and the period of the original signal. Refer to FIG. 6b, a DfT (Design for Test) circuit is embedded in the measurement circuit. Before implement with full scan design, the fault coverage achieved is only 63%. If only full scan is implemented, then the fault coverage can be improved as 82%. When the circuit further comprises a multiplexer 65 and a D flip-flop 66 for correcting random output of latch chain, the fault coverage is increased as 91% and the test coverage is increased as 100%. To realize the function of TDC 6 described previously, the timing design implemented in the embodiment according to the present invention is as shown in FIG. 7. A first clock clk is delayed for a time td and results in a second clock clkd. The clkd is used for assisting to the timing control of a reset signal rst and control signal enable. When the first clock goes to high level, the operation mode is in the RUN mode. When the first clock goes to low level, the operation mode is in a HOLD mode. When the reset signal rst goes to rising edge, the value of the encoder and counter is latched. It follows that the latch chain is cleared to zero and the operation mode enters into CLEAR mode before the following first clock clk goes to high level. The present invention is characterized by being able to perform operating modes of HOLD, CLEAR and RUN in the same cycle, and the digital signal measured is in proportion to the time duration of high level. Consequentially, the width of high (the time duration that signal equals to 1) must have to form a stable duty cycles, thus the measurement result is in proportion to the period. The divider used in the present invention provides a stable duty cycle signal to the TDC when n>=2. The present invention provides a continuous measuring of period for each clock generated without waiting. Equalization encoding is another concept proposed in the present invention for eliminating measurement errors. Such measurement errors are caused by the difference between the rising-time and the falling-time in each standard cell. Such measurement errors also result in depicted errors of the TDC output. An example is described as below. As shown in the FIG. 8, the first column represents steps the signal in the latch chain moved, and the second column represents the actual delay time depicted. It is noted that the difference between the beginning digital values is low due to the delay time is short, and the difference between the following digital values is high due to the delay time is long. If a traditional encoding (T.E.) is implemented in the example, the same steps result in the same code. Thus, based on the T.E., depicted time represented by the digital values output from the TDC results in significant errors. The third column is the T.E. The fourth column is the depicted delay indicated by each code. The fifth column is the error percentage of the difference of indicated time and the actual time, and divided by the average time step, wherein the average time step is 2.4 ns/8=0.3 ns: Error = Encoded ⁢ ⁢ Delay - Actual ⁢ ⁢ Delay Averge ⁢ ⁢ Time ⁢ ⁢ Step × 100 ⁢ ⁢ % The equalization encoding proposed by the present invention is a method for selecting a code, which is the closest value of the output digital value output from the TDC. The delays between adjacent codes almost equal to each other hence the method is called equalization code. Such method can be designed in the register transfer level before the synthesis. The area and speed achieved by the circuit mentioned above is similar to the area and speed achieved by the circuit synthesized by T.E. The sixth column in the FIG. 8 is the equalization encoding (E.E.) proposed in the present invention. The seventh column is the depicted time indicated. The eighth column is the accumulated delay time based on the E.E. according to the present invention. According to data in the eighth column, it is noted that the E.E. of present invention significantly eliminates the errors compare to the T.E. (III) Simulation Result of the Embodiment of the Present Invention Simulation result of the embodiment is described in the FIG. 9, FIG. 10 and FIG. 11 for a TSMC 0.25 um design, wherein T is the period of an input signal, σx is the jitter of the input signal, n is the divisor applied in the input divider, and mean and var2 are the digital output values from the embedded test circuit. Jitter σm and the measurement errors can be attained from the equation as follows: σ m = n × var ⁢ ⁢ 2 × T mean error = σ m - σ x σ x × 100 ⁢ ⁢ % For signal with different input period, if n is fixed as 64, and input signal jitter is fixed as 300 ps, then the measurement error is less than 4.23%. The minimum of an input period is limited by three factors. The first is the maximum of the operating speed of the divider, second is the maximum operating speed of the TDC, the third is the jitter can not too large compared to the signal average period. The last row shown in the FIG. 9 is in violation of the third factor mentioned above. Those factors can be expressed in the equations as follows: T≧0.85 ns nT≧30 ns T≧10σx (If xi is within ±5 σx) The digital width of TDC determine the maximum of the input period. For a 12 bit design, if the signal period is lower than 0.3×20×212 (ns)=24.6 (us), the error is limited within 5%. Such a range of input signal is subject to the design of a circuit. FIG. 10 and FIG. 11 are simulation results of output jitter by different settings of the divisor and the input jitter. Most of the results indicate that the error is small. It is observed that, for signal having different σx, the n has to follow the equation below to limit the error within 5%. 0.3×{square root}{square root over (20)}<{square root}{square root over (n)}σx<0.3×27×⅕→1.34 ns<{square root}{square root over (n)}σx<7.68 ns Errors observed in the first row in the FIG. 10 and the first and the second row in the FIG. 11 are significant due to the fact that {square root}{square root over (n)}σx is too small. The last row in the FIG. 10 fails to perform the simulation because the {square root}{square root over (n)}σx is too large. In conclusion, given the period and jitter of a signal to be measured may be different, as long as an appropriate n is selected to introduce in the equations above, simulation results can be attained accurately. In example of the simulation result by the last row in the FIG. 11, the input clock is 1.5 ns and jitter is only 40 ps, for n=1024, the error is only 2%. Based on the accompanying drawings, a practical embodiment of a built-in jitter measurement circuit for a voltage-controlled oscillator and a phase-locked loop according to the present invention have been described. However, the present invention is not limited to the illustrated method. It will be apparent to those skilled in the art that various changes, improvements, and modifications can be made thereto without departing from the spirit or scope of the invention.