Abstract:
This invention relates to an optical mechanism comprising: an optical beam generating mechanism to generate an optical beam; and a unitary, transparent waveguide for guiding the optical beam to an optically writable surface wherein optical elements for guiding the optical beam are coated onto the waveguide to create a relatively compact optical system, a relatively low exit numerical aperture for the exit pupil, and for bending and re-directing the optical beam.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to an optical mechanism comprising: an optical beam generating mechanism to generate an optical beam; and a unitary, transparent waveguide for guiding the optical beam to an optically writable surface wherein optical elements for guiding the optical beam are coated onto the waveguide to create a relatively compact optical system, a relatively low exit numerical aperture for the exit pupil, and for bending and re-directing the optical beam. 
   2. Description of the Related Art 
   Prior to the present invention, as set forth in general terms above and more specifically below, it is known that optical disc drives have historically been used to optically read data from and optically write data to data regions of optical discs. More recently, optical disc drives have been used to optically write images to label regions of optical discs. For example, a type of optical disc is known in which a laser or other optical beam can be used to write to the label side of an optical disc. 
   A costly component of an optical disc drive is the optical pickup unit (OPU). The OPU is the optical mechanism by which an optical beam is generated, and then guided to the surface of an optical disc using a number of precisely arranged lenses and other components, including an objective lens, which have to be manufactured to high tolerances, and thus at high cost. Therefore, optical disc drives typically only have one OPU for cost and complexity reasons. An optical drive having just a single such optical mechanism for accessing both the label and the data sides of an optical disc, however, forces a user to remove the disc from the drive, flip it over, and reinsert the disc back into the drive when the optical drive needs to access the data side after having accessed the label side, and vice-versa. Consequently, a more advantageous optical disc drive, then, would be provided if only one OPU could be utilized. 
   It is also known, that conventional optical print heads (OPHs) use a non-waveguide optical path in the optical disk drive. The non-waveguide optical path can be constructed of plastic or metallic materials. The discrete optical components (objective lens, collimator, prism, and quarter wave element) are then cemented to the non-waveguide arm or optical pick-up unit (OPU)-sled assembly. The alignments of these optical components are very critical to the quality of the OPH. Also, the alignments can be costly as well as time consuming. Therefore, a further advantageous OPH, then, would be provided if a glass/quartz (or any high transmit and low birefringence material for labeling wavelength) are could be used in the OPH for disk labeling. 
   It is further known to use a unitary wave guide arm wherein optical elements are secured to the wave guide to provide the necessary reflection/refraction surfaces. As discussed above, the optical elements alignments and optical beam generating mechanism alignments are very critical to the quality of the OPH. Also, the alignments can be costly as well as time consuming. Finally, these type of wave guides utilize an extremely long path length. 
   It is apparent from the above that there exists a need in the art for a unitary, transparent glass/quartz (or any high transmit material for labeling wavelength) waveguide that utilizes optical elements that are placed onto the waveguide such that the waveguide creates a more compact assembly, employs a relatively low numerical aperture for the exit pupil that can be used in the OPH for disk labeling, and reduces the number of alignments. It is a purpose of this invention to fulfill this and other needs in the art in a manner more apparent to the skilled artisan once given the following disclosure. 
   SUMMARY OF THE INVENTION 
   Generally speaking, an embodiment of this invention fulfills these needs by providing an optical mechanism comprising: an optical beam generating mechanism to generate an optical beam; and a unitary, transparent waveguide for guiding the optical beam to an optically writable surface wherein optical elements for guiding the optical beam are coated onto the waveguide to create a relatively short optical beam path length, a relatively low numerical aperture for the exit pupil, and for bending and re-directing the optical beam. 
   In certain preferred embodiments, the optical beam generating mechanism is capable of generating an optical beam through the use of a laser diode. Also, the waveguide is constructed of any suitable moldable material upon which the optical elements such as multilayer anti-reflective, polarization separation coatings and reflective coatings can be placed such that the coatings have a high enough transmission and low enough birefringence. Finally, the optical mechanism measures characteristics of that beam as it is reflected back from the optically writable surface. 
   In another further preferred embodiment, a unitary, transparent glass/quartz (or any high transmit material and low birefringence for labeling wavelength) waveguide that utilizes optical elements that are placed onto the waveguide such that the waveguide creates a more compact assembly, employs a relatively low numerical aperture that can be used in the OPH for disk labeling, reduces the number of disparate optical elements, and reduces the number of alignments is disclosed. 
   The preferred optical mechanism, according to various embodiments of the present invention, offers the following advantages: lightness in weight; a more compact assembly; a relatively low numerical aperture; and decreased optical element/optical beam generating mechanism alignment complexity. In fact, in many of the preferred embodiments, these factors of shorter optical beam path length, lower numerical aperture, and decreased optical element/optical beam generating mechanism alignment complexity are optimized to an extent that is considerably higher than heretofore achieved in prior, known optical mechanisms. 
   The above and other features of the present invention, which will become more apparent as the description proceeds, are best understood by considering the following detailed description in conjunction with the accompanying drawings, wherein like characters represent like parts throughout the several views and in which: 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The drawings referenced herein form a part of the specification. Features shown in the drawing are meant as illustrative of only some embodiments of the invention, and not of all embodiments of the invention, unless otherwise explicitly indicated. 
       FIG. 1  is a diagram of an optical disc drive, according to an embodiment of the present invention. 
       FIG. 2  is a top view illustration an optical mechanism for the optical disc drive of  FIG. 1 , according to one embodiment of the present invention. 
       FIG. 3  is a schematic illustration a unitary, transparent waveguide for guiding the optical beam of  FIG. 2 , according to another embodiment of the present invention. 
       FIG. 4  is a side view illustration an optical mechanism for the optical disc drive of  FIG. 2 , according to another embodiment of the present invention. 
       FIG. 5  is a graphical illustration of the intensity profile of the focused beam at the labeling layer, according to another embodiment of the present invention. 
       FIG. 6  is a graphical illustration diagram of the irradiance pattern of the focused beam at the labeling layer, according to another embodiment of the present invention. 
       FIG. 7  is a graphical illustration of a x-intensity profile plot of the focused write beam at the labeling layer, according to another embodiment of the present invention. 
       FIG. 8  is a graphical illustration of a y-intensity profile plot of the focused write beam at the labeling layer, according to another embodiment of the present invention. 
       FIG. 9  is a diagram of an optical disc drive having two optical mechanisms for accessing both sides of an optical disc without having to have a user remove the disc from the drive, flip it over, and reinsert the disc into the drive, according to an embodiment of the invention. 
       FIG. 10  is a flowchart of a method of use for an optical disc drive having an optical mechanism with a light pipe, according to an embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   In the following detailed description of exemplary embodiments of the invention, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific exemplary embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized, and logical, mechanical, and other changes may be made without departing from the spirit or scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims. 
   With reference first to  FIG. 1 , there is illustrated one preferred embodiment for use of the concepts of this invention.  FIG. 1  shows an optical disc drive  100 , according to an embodiment of the invention. The optical drive  100  is for reading from and/or writing to an optical disc  102  which has a label side  104 A opposite a data side  104 B. More specifically, the optical drive  100  is for reading from and/or writing to an optically writable label side  104 A of the optical disc  102 , and/or an optically writable label side  104 B of the optical disc  102 , which are collectively referred to as the sides  104  of the optical disc  102 . 
   The optically writable data side  104 B of the optical disc  102  includes a data region on which data may be optically written to and/or optically read by the optical drive  100 . The data side  104 B is thus the side of the optical disc  102  to which binary data readable by the optical drive  100  and understandable by a computing device is written, and can be written by the optical drive  100  itself. For instance, the data side  104 B may be the data side of a compact disc (CD), a CD-readable (CD-R), which can be optically written to once, a CD-readable/writable (CD-RW), which can be optically written to multiple times, and so on. The data side  104 B may further be the data side of a digital versatile disc (DVD), a DVD-readable (DVD-R), or a DVD that is readable and writable, such as a DVD-RW, a DVD-RAM, or a DVD+RW. The data side  104 B may further be the data side of a high-capacity optical disc, such as a Blu-ray optical disc, and so on. Furthermore, there may be a data region on each side of the optical disc  102 , such that the optical disc is double sided, and such that there is a label region on at least one of the sides of the disc. 
   The optically writable label side  104 A of the optical disc  102  includes a label region on which an image may be optically written thereto, to effectively label the optical disc  102 . The label side  104 A is thus the side of the optical disc  102  to which visible markings can be optically written to realize a desired label image. It is noted in one embodiment that both the sides  104 A and  104 B of the optical disc  102  may have both label regions and data regions. 
   The optical drive  100  is depicted in  FIG. 1  as including an optical mechanism  106 . Different and specific embodiments of the optical mechanism  106  are described in detail later in the detailed description. In general, however, the optical mechanism  106  does not employ an objective lens, and further employs a unitary, transparent waveguide to direct a generated optical beam to the surface of the optical disc  102 . As such, the optical mechanism  106  is advantageous because it may not need costly, complex, and precisely arranged lenses and other components. 
   In particular, the optical mechanism  106  employing a unitary, transparent waveguide, and not employing an objective lens, is applicable to using the optical mechanism  106  to optically write to the label side  104 A of the optical disc  102 , because less precision is needed to optically write to and/or read from the label side  104 A, as opposed to optically writing to and/or reading from the data side  104 B. In such an embodiment of the invention, the optical mechanism  106  may be referred to as an optical print head, because it is used to optically write marks to the label side  104 A, to achieve a desired image on the label side  104 A of the optical disc  102 . However, in other embodiments, the optical mechanism  106  may also be able to be used to optically write to and/or read from the data side  104 B, too. 
   The optical drive  100  is also depicted in  FIG. 1  as including a spindle  110 A and a spindle motor  110 B, which are collectively referred to as the first motor mechanism  110 . The spindle motor  110 B rotates the spindle  110 A, such that the optical disc  102  correspondingly rotates. The first motor mechanism  110  may include other components besides those depicted in  FIG. 1 . For instance, the first motor mechanism  110  may include a rotary encoder or another type of encoder to provide for control of the spindle motor  110 B and the spindle  110 A. 
   The optical drive  100  is further depicted in  FIG. 1  as including a sled  114 A, a coarse actuator  114 B, a fine actuator  114 C, and a rail  114 D, which are collectively referred to as the second motor mechanism  114 . The second motor mechanism  114  moves the optical mechanism  106  to radial locations relative to a surface of the optical disc  102 . The coarse actuator  114 B is or includes a motor that causes the sled  114 A, and hence the fine actuator  114 C and the optical mechanism  106  situated on the sled  114 A, to move radially relative to the optical disc  102  on the rail  114 D. The coarse actuator  114 B thus provides for coarse or large radial movements of the fine actuator  114 C and the optical mechanism  106 . 
   By comparison, the fine actuator  114 C also is or includes a motor, and causes the optical mechanism  106  to move radially relative to the optical disc  102  on the sled  114 A. The fine actuator  114 C thus provides for fine or small movements of the optical mechanism  106 . The second motor mechanism  114  may include other components besides those depicted in  FIG. 1 . For instance, the second motor mechanism  114  may include a linear encoder or another type of encoder to provide for control of the coarse actuator  114 B and the sled  114 A. Note that it is possible to use a single motor for both actuations, under the condition that it has enough accuracy to provide acceptable print quality to the human eye. This single motor may or may not use an encoder strip to provide feedback to enhance accuracy of positioning and hence print quality. Furthermore, either or both of the motor mechanisms  110  and  114  may be considered as the movement mechanism of the optical drive  100 . 
   It is noted that the utilization of a fine actuator  114 C and a coarse actuator  114 B, as part of the second motor mechanism  114 , is representative of one, but not all, embodiments of the invention. That is, to radially move the optical mechanism  106  in relation to the optical disc  102 , the embodiment of  FIG. 1  uses both a fine actuator  114 C and a coarse actuator  114 B. However, in other embodiments, other types of a second motor mechanism  114 C can be used to radially move the optical mechanism  106  in relation to the optical disc  102 , which do not require both a fine actuator  114 C and a coarse actuator  114 B. For instance, a single actuator or other type of motor may alternatively be used to radially move and position the optical mechanism  106  in relation to the optical disc  102 . One such alternative embodiment is described later, at the end of the detailed description. 
   The optical drive  100  is additionally depicted in  FIG. 1  as including a controller  116 . The controller  116  can in one embodiment include at least a rotation controller  116 A, a coarse controller  116 B, and a fine controller  116 C. The mechanisms  116  may each be implemented in software, hardware, or a combination of software and hardware. The rotation controller  116 A controls movement of the spindle motor  110 B, and thus controls rotation of the optical disc  102  on the spindle  110 A, such as the angular velocity of the rotation of the optical disc  102 . The coarse controller  116 B controls the coarse actuator  114 B, and thus movement of the sled  114 A on the rail  114 D. The fine controller  116 C controls the fine actuator  114 C, and thus movement of the beam source  106 A on the sled  114 A. 
   The controller  116  may further include other components besides those depicted in  FIG. 1 . For instance, the controller  116  can be responsible for turning on and off, and focusing, the optical beam  316  ( FIG. 3 ). In addition, as can be appreciated by those of ordinary skill within the art, the components depicted in the optical drive  100  are representative of one embodiment of the invention, and do not limit all embodiments of the invention. 
     FIG. 2  shows the optical mechanism  106  of the optical disc drive  100  in detail, according to an embodiment of the invention. The optical mechanism  106  includes carriage rails  202 , an optical beam generating mechanism  204 , a carriage  206 , and unitary, transparent waveguide  208 . The carriage rails  202  are rigidly connected to fine actuator  114 C ( FIG. 1 ). Carriage rails  202 , preferably, are constructed of any suitable, durable material. Carriage  206  is rigidly connected to carriage rails  202 . Carriage  206 , preferably, is constructed of any suitable, durable material. Optical beam generating mechanism  204  is rigidly connected to carriage  206 . Optical beam generating mechanism  204 , preferably, includes a conventional laser diode that is capable of emitting a laser beam  304  ( FIG. 3 ). One example of this diode is Sharp Corporation Japan&#39;s GH07P28 series of laser diodes. Unitary, transparent waveguide  208  is rigidly connected to carriage  206  such that an optical beam  304  originating from optical beam generating mechanism  204  can be traversed through waveguide  208  such that it interacts with the label side  104 A of the optical disc  102  to produce marking. Waveguide  208 , preferably, is constructed of any suitable, durable, transparent material that is capable of being molded. In particular, waveguide  208  is a single block of glass or polymeric material which provides all of the focusing optics and folding mirrors built in a single molded step. The multilayer coatings are placed on the waveguide after the molding process is complete. The multilayer coatings can be placed between two molding processes. Multilayer coatings provide mirror areas for the reflective optics and mirrors and areas of high transmission for light entering from the optical beam generating mechanism  204  and exiting onto label side  104 A. The multilayer coatings can also create a beam splitter, a polarized beam splitter, an anti-reflective layer and other such reflective optics. Preferably, the total thickness required for optical mechanism  106  is 6.45 millimeters with a conventional 5.6 millimeter diameter optical beam generating mechanism  204 . It is to be understood that other packages are available that can reduce this distance even further. It is to be further understood that since all the optics are formed in one molded step, the cost is very low and optical element alignment errors are reduced. Finally, the waveguide  208  creates a relatively compact optical system that exhibits low birefringence, a relatively low exit numerical aperture for the exit pupil, and for bending and re-directing the optical beam. 
     FIG. 3  shows the optical mechanism  106  in detail, according to another embodiment of the invention. Like-numbered components between  FIG. 3  and  FIG. 2  operate at least substantially the same between the optical mechanisms  106  of  FIGS. 2 and 3 , and the description of such components is not repeated in relation to  FIG. 3  unless the manner by which they operate is different in relation to  FIG. 3 . 
   With respect to  FIG. 3 , waveguide  208  is illustrated. Waveguide  208  includes, in part, multi-layer, anti-reflective coating or lens  306 , multi-layer reflective coating  310 , multi-layer, anti-reflective coating or lens  314 , and conventional laser beam sensor  318 . During the construction of waveguide  208 , waveguide  208  is molded. Portions of waveguide  208  are conventionally covered so that only the areas where anti-reflective coatings or lenses are to be placed are left uncovered. The anti-reflective coatings or lenses are then conventionally applied. It is to be understood that the anti-reflective coating or lens should be designed to work with the wavelength of interest. Also, the anti-reflective areas are conventionally covered and a reflective coating is conventionally placed on the remainder of waveguide  208 . It is to be further understood that the reflective coating should be designed to work with the wavelength of interest. Finally, it is to be understood that an anti-reflective coating or lens is equal to a high transmission coating or lens. This means that a light beam will transmit through. On the other hand, a reflective coating highly reflects the light beam in an opposite direction such that no light beam is transmitted through. 
   During the operation of optical mechanism  106 , a laser beam  304  is emitted from laser diode  204 . Laser beam  304  enters into waveguide  208  and interacts with anti-reflective coating  306 . Anti-reflective coating  306  causes the laser beam to transmit through/focus and form laser beam  308 . Laser beam  308  interacts with reflective coating  310  to create laser beam  312 . Laser beam  312  interacts with anti-reflective coating  314 . After laser beam  312  interacts with anti-reflective coating  314 , laser beam  312  is further transmitted through/focused such that laser beam  316  exits waveguide  208  and optically writes marks to the label side to achieve a desired image on the label side of the optical disc. 
   The reflected optical beam  320  is similarly routed back through waveguide  208  at curved section  322 . Curved section  322  is also coated with the same multi-layer, anti-reflective coating, as discussed above. The reflected optical beam  320  is transmitted through/focused by curved section  322  such that it impinges upon conventional laser beam detector/sensor  318 . The location of laser beam  316  is then conventionally monitored/adjusted, according to conventional techniques. 
     FIG. 4  shows a side view of carriage rails  202 , laser diode  204 , and carriage  206 . As shown in  FIG. 4 , laser beam  316  exits waveguide  208  and optically writes marks to the label side  104 A to achieve a desired image on the label side  104 A of the optical disc  102 . Preferably, laser beam  316  should have a width of between 32 μm and 18 μm full width half maximum (FWHM) for proper labeling applications. 
     FIG. 5  shows the intensity profile of the focused beam  316  ( FIG. 3 ) at the label side  104 A ( FIG. 1 ). This intensity profile demonstrates that the optical mechanism  106  can create a suitable intensity of the focused beam  316  ( FIG. 3 ) at the label side  104 A ( FIG. 1 ). 
     FIG. 6  shows the irradiance pattern of the focused beam  316  ( FIG. 3 ) at the label side  104 A ( FIG. 1 ). This irradiance pattern demonstrates that the optical mechanism  106  can create a suitable irradiance of the focused beam  316  ( FIG. 3 ) at the label side  104 A ( FIG. 1 ). 
     FIG. 7  shows the intensity of the x-intensity profile of the focused beam  316  ( FIG. 3 ) at the label side  104 A ( FIG. 1 ).  FIG. 8  shows the intensity of the y-intensity profile of the focused beam  316  ( FIG. 3 ) at the label side  104 A ( FIG. 1 ). Both profiles showed good axisymmetric Gaussian profile shapes. 
   The optical beam  316  is output onto the surface of the optical disc  102 , such as the label side  104 A, at a spot that may have a circular or an oval shape. In some situations, it may be desired to reduce the size, or the surface area, of this spot, for better precision and to achieve higher pixel density on the surface of the optical disc  102 . Reducing the size of the spot at which the optical beam  212  is output from the waveguide  208  may be modified by changing the waveguide  208 . 
   The optical mechanism  106  has been described as having an optical beam-generating mechanism  204  that is specifically, or that specifically includes, an optical beam diode, such as a laser diode, which emits an optical beam  304  that can be a laser beam, for instance. In other embodiments, the optical-beam generating mechanism  204  may be or include components other than an optical beam diode like a laser diode. 
   The optical mechanism  106  of various embodiments of the invention that have been described is at least for optically writing to the label side  104 A of the optical disc  102 . In one embodiment, the optical mechanism  106  may be able to be also employed to optically write to and/or optically read from the data side  104 B of the optical disc  102 . In such an embodiment, the optical disc  102  would have to be removed from the optical disc drive  100 , flipped or turned over, and reinserted into the optical disc drive  100  for the optical mechanism  106  to access the label side  104 A after the data side  104 B of the optical disc  102  has been accessed, and vice-versa. This can be inconvenient for the user, however. In such situations, and in the embodiment where the optical mechanism  106  cannot be employed to optically write to and/or optically read from the data side  104 B of the optical disc  102 , the optical disc drive  100  may be modified to include two optical mechanisms, including the optical mechanism  106 . 
     FIG. 9  shows the optical disc drive  100 , according to such an embodiment of the invention. In particular, the optical disc drive  100  includes the optical mechanism  106  that has been described, as well as another optical mechanism  902  situated or disposed opposite to the optical mechanism  106 . The other components of the optical disc drive  100  that are depicted in  FIG. 1 , such as various motor mechanisms and controllers, are not shown in  FIG. 9  for illustrative convenience. Furthermore, the optical disc drive  100  of  FIG. 9  may have additional components besides those depicted in  FIG. 9 , such as one or more motor mechanisms for the optical mechanism  902 . The optical mechanism  106  is incident to the label side  104 A of the optical disc  102  that has been inserted into the optical disc drive  100 , whereas the optical mechanism  902  is incident to the data side  104 B of the optical disc  102  that has been inserted into the optical disc drive  100 . 
   As a result, access to both the label side  104 A and the data side  104 B of the optical disc  102  can be achieved by the optical disc drive  100 , without having to have the user remove the disc  102  from the drive  100 , flip it over, and reinsert the disc  102  into the drive  100  for the drive  100  to access the label side  104 A after having accessed the data side  104 B, and vice-versa. The optical mechanism  106  can be in accordance with the embodiments of the invention that have been described, such that it does not employ an objective lens. By comparison, the optical mechanism  902  in one embodiment can be a conventional optical pickup unit (OPU), and thus employ an objective lens as well as other costly and complex components. In another embodiment, however, the optical mechanism  902  may be another instance of the optical mechanism  106  that has been described. 
     FIG. 10  shows a method  1000  for optically writing an image to the optically writable label side  104 A of the optical disc  102  with the optical drive  100  having the optical mechanism  106  with the waveguide  208  that has been described, according to an embodiment of the invention. The method  1000  may thus be performed by the components of the optical drive  100  that have been described. At least some components of the method  1000  may be implemented as computer program parts of a computer program stored on a computer-readable medium. The medium may be a magnetic storage medium, such as a hard disk drive, an optical storage medium, a magnetic optical storage medium such as an optical disc, and/or a semiconductor storage medium, such as a memory, among other types of computer-readable media. 
   The optical disc  102  is initially rotated within the optical drive  100  (step  1002 ). The optical mechanism  106  is radially moved relative to the optical disc  102  to cause the optical mechanism  106  to be incident to a given radial location of a label region of the optical disc  102  (step  1004 ). For instance, where the optical mechanism  106  includes the carriage  206 , the carriage  206 , that has been described, can be rotated. The label region of the optical disc  102  can, in one embodiment, be the label side  104 A of the optical disc  102 . The optical beam  316  is then selectively generated by the optical mechanism  106  (step  1006 ). 
   The optical beam  316  is routed to the radial location of the label region of the optical disc  102  to which the optical mechanism  106  is incident using the waveguide  208 , as has been described (step  1008 ). Routing of the optical beam  316  that is selectively generated and routed to the radial location of the label region of the optical disc  102 , as the optical disc  102  is being rotated, therefore enables the optical beam  316  to optically write to this radial location a portion of an image to be optically written to the label region (step  1010 ). Steps  1004 ,  1006 ,  1008 , and  1010  of the method  1000  are repeated for new radial locations of the label region of the optical disc  102 , until the desired image has been completely written to the label region of the optical disc  102 . 
   It is to be understood that the flowchart of the  FIG. 10  shows the architecture, functionality, and operation of one implementation of the present invention. If embodied in software, each block may represent a module, segment, or portion of code that comprises one or more executable instructions to implement the specified logical function(s). If embodied in hardware, each block may represent a circuit or a number of interconnected circuits to implement the specified logical function(s). 
   Also, the present invention can be embodied in any computer-readable medium for use by or in connection with an instruction-execution system, apparatus or device such as a computer/processor based system, processor-containing system or other system that can fetch the instructions from the instruction-execution system, apparatus or device, and execute the instructions contained therein. In the context of this disclosure, a “computer-readable medium” can be any means that can store, communicate, propagate or transport a program for use by or in connection with the instruction-execution system, apparatus or device. The computer-readable medium can comprise any one of many physical media such as, for example, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor media. More specific examples of a suitable computer-readable medium would include, but are not limited to, a portable magnetic computer diskette such as floppy diskettes or hard drives, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory, or a portable compact disc. It is to be understood that the computer-readable medium could even be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via, for instance, optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a single manner, if necessary, and then stored in a computer memory. 
   Those skilled in the art will understand that various embodiment of the present invention can be implemented in hardware, software, firmware or combinations thereof. Separate embodiments of the present invention can be implemented using a combination of hardware and software or firmware that is stored in memory and executed by a suitable instruction-execution system. If implemented solely in hardware, as in an alternative embodiment, the present invention can be separately implemented with any or a combination of technologies which are well known in the art (for example, discrete-logic circuits, application-specific integrated circuits (ASICs), programmable-gate arrays (PGAs), field-programmable gate arrays (FPGAs), and/or other later developed technologies. In preferred embodiments, the present invention can be implemented in a combination of software and data executed and stored under the control of a computing device. 
   It will be well understood by one having ordinary skill in the art, after having become familiar with the teachings of the present invention, that software applications may be written in a number of programming languages now known or later developed. 
   Although the flowchart of the  FIG. 10  shows a specific order of execution, the order of execution may differ from that which is depicted. For example, the order of execution of two or more blocks may be scrambled relative to the order shown. Also, two or more blocks shown in succession in  FIG. 10  may be executed concurrently or with partial concurrence. All such variations are within the scope of the present invention. 
   Once given the above disclosure, many other features, modifications or improvements will become apparent to the skilled artisan. Such features, modifications or improvements are, therefore, considered to be a part of this invention, the scope of which is to be determined by the following claims.