Abstract:
A timing device for visually indicating the passage of a duration of time is disclosed. The timing device and system, in accordance with the embodiments of the invention, is sectioned into zones with different rates of reactivity and/or sensitivity, such that the zones change color or darken over a range of times. The timing device, in accordance with further embodiments of the invention, comprises a film, that is a color film, a black and white film or a combination thereof, with a photographic layer and a developer layer, which when brought together activate the device. The photographic film can be pre-exposed to light or heat to control the rate that the film changes color or darkens after being activated. Pieces of timing film, in accordance with further embodiments of the invention, have adhesion layers for attaching the pieces of timing film to perishable articles or packages containing perishable articles and are preferably configured to be dispensed from a roll or stack of the timing film.

Description:
RELATED APPLICATION(S)  
       [0001]    This Patent Application is a continuation-in-part application of the co-pending U.S. Pat. application Ser. No. 10/319,233, filed Dec. 13, 2002, and entitled “TIMING SYSTEM AND DEVICE AND METHOD FOR MAKING THE SAME”, which claims priority under 35 U.S.C. §119 (e) from the U.S. Provisional Patent Application, Ser. No. 60/339,744, filed Dec. 13, 2001, and entitled “TIME DOT”. The U.S. patent application Ser. No. 10/319,233, filed Dec. 13, 2002, and entitled “TIMING SYSTEM AND DEVICE AND METHOD FOR MAKING THE SAME” and the Provisional Patent Application Serial No. 60/339,744 filed Dec. 13, 2001, and entitled “TIME DOT” are both hereby incorporated by reference. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The invention relates to timing systems and devices and a method for making the same. More specifically, the invention relates to systems and devices for and methods of indicating the passage of a duration time.  
         BACKGROUND OF THE INVENTION  
         [0003]    There are a number of different timing systems and devices, generally referred to as time-temperature indicators (TTIs) which can be used to monitor the exposure of objects to a range of temperatures over a specified period of time. In an early example, Witonsky, in U.S. Pat. No. 3,942,467 describes a time-temperature indicator with an encapsulated inner container and a pH sensitive dye solution contained therein. The device of Witonsky further has an encapsulated outer container containing an organic material which undergoes solvolysis. The outer container and the inner container are separated by a membrane. When the membrane between the inner and the outer container is broken, the contents of the containers mix and over a period of time change color thus providing an indication of the passage of a duration of time. A number of other time-temperature indicators utilize wicking techniques (such as described in U.S. Pat. No. 5,709,472 and U.S. Pat. No. 6,042,264, both issued to Prusik et al.) or diffusion layer techniques (such as described in U.S. Pat. No. 4,629,330 issued to Nichols and U.S. Pat. Nos. 5,930,206 and 5,633,835 both issued to Haas et al.). In U.S. Pat. No. 6,198,701 issued to De Jonghe et al., an electrochemical timing device is described, whereby consumption of an electrode is used to provide an indication of the passage of a duration of time.  
           [0004]    Time-temperature indicators can have a number of different applications for indicating when an event or activity needs to take place. For example, time-temperature indicators have applications for indicating when the perishable materials have expired and need to be thrown out. Time-temperature indicators also have applications for general inventory management, for monitoring projects, activities and a host of other time and/or temperature dependent events. Therefore, there is a continued need to develop reliable timing systems and devices which can be used for a variety of different applications.  
         SUMMARY OF THE INVENTION  
         [0005]    The present invention is directed to a device and system for indicating the passage of a duration of time and a method of making the same. While, the present invention is referred to herein as a timing device, it is understood that the timing device of the present invention is also sensitive to temperature. While a timing device, in accordance with the embodiments of the invention, can be configured to be more or less sensitive to temperature, the timing device will generally react, or change, at a faster rate at higher temperatures.  
           [0006]    A timing device, in accordance with the embodiments of the present invention is a chemical-based timing device, electrochemical-based timing device, or a combination thereof. The timing device, when actuated, provides a visual indication of a passage of time. The timing device is configured as a “stand alone” indicator or, alternatively, is configured to be coupled with any number of circuits which also provide an audible signal or otherwise sense and/or store information regarding the operation of the device.  
           [0007]    The device preferably comprises a lens, a base and means for altering the visibility of the base through the lens and thereby indicating the passage of a duration of time. The means for altering the visibility of the base through the lens preferably comprises an optical medium positioned between the lens and the base. The optical medium comprises chemicals and/or elements of a battery that react or otherwise change over time and, thereby alters the visibility of the base through the lens. For example, one or more of the materials, layers or components of the optical medium are converted from opaque to transparent or, alternatively, from transparent to opaque, thereby increasing or decreasing the visibility of the base through the lens, respectfully. Alternately, one or more of the materials, layers or components of the optical medium are dissolved or depleted, thereby altering the visibility of the base through the lens.  
           [0008]    In accordance with the embodiments of the invention, the optical medium comprises a solid layer positioned between the lens and the base, also referred to herein as a lens coating layer, and a fluid layer positioned between the solid layer and the base. The fluid layer contains gel, water and any suitable chemical(s) required to change the solid layer from opaque to transparent, change the layer from transparent to opaque, deplete the solid layer or dissolve the solid layer, as explained in detail below. In the preferred embodiment of the invention, the solid layer is opaque and when the device is actuated, the fluid layer dissolves the solid layer over a duration of time, thereby making the base visible through the lens and indicating the passage of a duration of time.  
           [0009]    In further embodiments of the invention, a timing device comprises an indicator between the lens and the lens coating layer to enhance the visual indication of the passage of time. Suitable indicators are fluids or solid, and can include, but are not limited to pH indicators and reactive dye indicators, which generate a color change when reacted with the fluid layer, after the fluid layer sufficiently depletes or dissolves the lens coating layer. Alternatively, the lens coating layer is a semi-porous membrane layer, wherein the indicator provides a color change when a sufficient amount of the reactive species from the fluid medium migrates through the membrane layer.  
           [0010]    In still further embodiments of the invention, a timing device comprises a battery, wherein at least a portion of the optical medium between the solid layer and the base actively participates in an electrochemical process resulting in a visual change indicating the passage of a duration of time. In accordance with this embodiment of the invention, the battery is a galvanic cell and the optical medium comprises an electrolyte. A galvanic cell is a battery where reduction and oxidation of species within the battery will occur spontaneously as long as there is a conductive path from a first electrode of the cell to a second electrode of the cell. In operation a material within the electrolyte is plated between the base and the lens, thereby reducing the visibility of the base through the lens. Alternatively, an opaque electrode positioned between the lens and the base is depleted, thereby increasing the visibility of the base through the lens.  
           [0011]    In still further embodiments of the invention, the battery is an electrolytic cell. An electrolytic cell requires a current from another battery, or other current source, to drive the reduction and oxidation of species within the battery. In accordance with this embodiment, a current from an external battery, or current source, flows through the battery and a material within the electrolyte is plated out between the lens and the base, thereby reducing the visibility of the base through the lens. Alternatively, an opaque electrode positioned between the lens and the base is depleted, thereby increasing the visibility of the base through the lens.  
           [0012]    A timing device, in accordance with the embodiments of the invention, is actuated using any number of different mechanisms or combination of mechanisms. For example, where the timing device is a chemical-based timing device, the timing device is preferably formed in parts, wherein a first part comprises a first reactive region and a second part comprises a second reactive region. To form an activated device, the first part and the second part are brought together and the first reactive region and the second reactive region are held eclipsed and in contact. Alternatively, a chemical-based timing device comprises a membrane or a removable structure separating the reactive regions of the device, wherein the membrane is broken or the structure is removed to activate the device.  
           [0013]    Where the timing device is an electrochemical-based timing device, the device is preferably actuated by a switch mechanism that closes a circuit between electrode elements of a galvanic or an electrolytic cell. Alternatively, the device is fabricated in parts as described above, wherein the parts have contact features, which when brought together close a circuit between the electrode elements of a galvanic or an electrolytic cell. An actuator switch, in accordance with further embodiments of the invention, is in electrical communication with a thermosensor, wherein the thermosensor instructs the actuator switch to close a circuit between electrode elements of a galvanic or an electrolytic cell within a range of temperatures.  
           [0014]    In accordance with yet further embodiments of the invention, a timing device and system comprises a photo-sensitive component, element or film. For example, a timing device comprises a piece of photographic film, which is color film, black and white film or a combination thereof. The photographic film is formed from a base with a photographic medium coated or deposited thereon, wherein the photographic film is capable of being activated to change color or shade and thereby indicate the passage of a duration of time. The photographic material is any photographic medium, but preferably comprises a silver-based material including, but not limited to, silver chloride, silver fluoride, silver iodide and/or combinations thereof. In yet other embodiments of the invention the photographic medium comprises a silver-soap (Ag +  cations in a fatty acid such as stearic acid) often used in thermally-activated films. Where the photographic medium is a silver halide, the silver halide is mixed with a binder, such as cellulose or gelatin, to hold the silver halide material on the base.  
           [0015]    The photographic material, in accordance with the embodiments of the invention, is made to be thermally and/or light sensitive using any number of techniques known in the art, including the addition of sulfur and gold and/or a dye, such as an infrared absorbing dye. To activate the photographic medium a developer is applied to the film. There are a number of materials that can be used for developing photographic materials, such as hydroquinone-based developers. Generally, all developers contain chemicals that assist in the reduction of silver halide or silver cations to form a darkened or colored image.  
           [0016]    In accordance with the embodiments of the invention, a developer is incorporated into the construction of the film and a timing device is thermally activated or is activated by removing a barrier between the photographic material and the developer. Alternatively, the photographic material and the developer are included on separate parts or regions of a timing device and are activated by bringing together a part or region of the film with the photographic material with a part or region of the film with the developer.  
           [0017]    In accordance with yet further embodiments of the invention, a device comprises a film with zones that change color at different rates and, therefore, provide an indication of the passage of a range of times. Each of the zones comprises a photographic material, as explained above, or other chemical and/or electrochemical materials that can be activated to change color at different rates. When the zones comprise photographic materials, the zones are made to have different reaction rates by using photographic materials with different sensitivities to heat, light and/or developer, and/or by varying the thickness of diffusion layers deposited over the zones. In accordance with further embodiments of the invention, the zones are made to have different rates of reaction and/or sensitivity to a developer by pretreating the zones to a range of different light and/or heat exposures, wherein the zones with longer exposures will develop and change color faster than zones with shorter exposures.  
           [0018]    A system, in accordance with the embodiments of the invention, comprises a timing film, such as described above, and further comprises an adhesion layer for attaching pieces of film to consumer articles, such as containers of leftover food. The system also preferably comprises a dispenser for conveniently dispensing pieces of film from a stack or roll of the timing film and means, such as a magnet, for attaching the dispenser to a household appliance.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0019]    FIGS.  1 A-B show a schematic representation of a timing device, in accordance with the embodiments of the invention.  
         [0020]    [0020]FIG. 2 shows a schematic representation of a timing device, in accordance with a preferred embodiment of the invention.  
         [0021]    FIGS.  3 A-C show systems for assembling timing devices, in accordance with the method of the present invention.  
         [0022]    FIGS.  4 A-C show schematic cross sectional views of several timing device configurations, in accordance with the embodiments of the invention.  
         [0023]    [0023]FIG. 5 shows a piece of timing film with a plurality of zones for indicating the passage of a range of times, in accordance with the embodiments of the invention.  
         [0024]    [0024]FIG. 6 is a cross-sectional representation of a section of timing film, in accordance with the embodiments of the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0025]    Referring to FIGS.  1 A-B, a timing device  100 , in accordance with the embodiments of the invention is a chemical-based timing device, an electrochemical-based timing device, or a combination thereof. The timing device  100  comprises a transparent lens  101 , a base  105  and an optical medium  103  therebetween. When the device  100  is actuated, the optical medium  103  is changed to a modified medium  103 ′, thereby altering the visibility of the base  105  through the lens  101  indicating the passage of a duration of time. The lens  101  and base  105  are formed from any suitable material, or combination of materials, including, but not limited to polymers and plastic materials.  
         [0026]    Still referring to FIGS.  1 A-B, the optical medium  103  comprises any number of different chemicals or elements which over the duration of time alter the visibility of the base  105  through the lens, as explained in detail below. Preferably, however, the base  105  becomes more visible through the lens  101  when the device  100  has expired. In order to enhance the visibility of the base  105  through the lens  101 , when the device  100  has expired, the base  105  is preferably brightly colored and/or has indicia printed thereon, such that the bright color and/or the indicia are visible through the lens  101  when the device is expired.  
         [0027]    Referring now to FIG. 2, in accordance with a preferred embodiment of the invention, a timing device  200  comprises a lens  201 , a base  211  and an optical medium  204 , as described above. The optical medium  204  preferably comprises a fluid layer  207 . The fluid layer  207  can be comprised of any number of fluid materials, but preferably comprises a transparent gel material, which is either acid or basic and which is either conductive or insulating, depending on the application at hand. The optical medium  204  also preferably comprises an opaque layer  205 , also referred to herein as a lens coating layer, which does not imply that the opaque layer  205  is necessarily coated directly on the lens  201 . The lens coating  205  is preferably formed from a material which will react with the fluid layer  207 , when the device  200  is activated. For example, the lens coating layer  205  is formed from a hardened gel, such as gelatin and thiosulfate. Preferably, the liquid layer  207  dissolves the lens coating layer  205  when the device  200  is activated, thereby increasing the visibility of the base therebelow and indicating the passage of a duration of time.  
         [0028]    Still referring to FIG. 2, in further embodiments of the invention, a timing device  200  comprises an activation layer  203 . The activation layer  203  comprises an indicator, such as a pH indicator which reacts with the fluid layer  207 , when the fluid layer  207  sufficiently depletes or dissolves the lens coating layer  205 . Alternatively, an indicator is incorporated into the lens coating layer  205  and is dissolved or leached by the fluid layer  207 , such that when the concentration of the indicator in the fluid layer  207  becomes sufficiently high, the fluid layer  207  changes color.  
         [0029]    In still further embodiments of the invention, the lens coating layer comprises a reactive species that reacts with an indicator in the fluid layer  207 . For example, the lens coating layer  205  comprises a base material, such as sodium bicarbonate, which is leached from the lens coating layer  205  or is dissolved into the fluid layer  207  from the lens coating layer  205 . The fluid layer  207  comprises a pH indicator and an acid material and when a sufficient amount of base material is dissolved into the fluid layer  207 , then the acid material is naturalized and the pH indicator changes color, indicating the passage of a duration of time.  
         [0030]    In still further embodiments of the invention, a timing device  200  comprises a diffusion material  209 . When the device  200  is activated, the diffusion material  209  begins to diffuse through the fluid layer  207 , as indicated by the arrows  215 . When the diffusion material  209  reaches the lens coating layer  205 , the diffusion material  209  reacts with the lens coating layer  205  to provide a color change, dissolve the lens coating layer  205  and react with the indicator layer  203 , or any combination thereof, to indicate the passage of a duration of time.  
         [0031]    Still referring to FIG. 2, a timing device  200 , in accordance with the embodiments of the present invention also comprises an attaching means  213  for attaching the timing device  200  to a product or an object (not shown). The attaching means  213  is any suitable attaching means, and preferably comprises an adhesive layer for sticking the device  200  onto the product or object.  
         [0032]    Now referring to FIG. 3A, a timing system  300 , in accordance with a preferred method of the invention, is fabricated in parts  310  and  320 . A first part  310  of the system  300  comprises a first reactive region  307  formed on a suitable base  301 . A second part  320  oft the system  300  comprises a second reaction region  305  formed on a clear lens  303 . One or both of the parts  310  and  320  comprise adhesive rings  311  and  309 . To actuate the system  300 , the parts are brought together such that the first reactive region  307  and the second reactive region  305  are eclipsed and in contact with each other. The adhesive rings  311  and  309  hold the first part  310  and the second part  320  together with the reactive regions  305  and  307  eclipsed and in contact. While in contact with each other, the first reactive region  307  and the second reactive region  305 , undergo a chemical, physical or electrochemical process which alters the visibility of the base  310  through the lens  303 , as described above. Each of the parts  310  and  320  of the system  300 , in accordance with further embodiments of the invention, comprise a protective covering (not shown), such as a cellophane, which acts protective of the reactive regions  307  and  305 , and is removed prior to use.  
         [0033]    Now referring to FIG. 3B, a system  320 , in accordance with the embodiments of the invention, is formed by fabricating a plurality of first reactive regions  322  on a first piece of tape  321  and a plurality of second reactive regions  324  on a second piece of tape  323 . The tapes  321  and  323  preferably have perforations  326  and  328  between each of the first reactive regions  322  and the second reactive regions  324 . The tapes  321  and  323  are preferably configured to be dispensed from a roll dispenser (not shown) or any other suitable dispenser. The dispenser can be dispenser configured to attach to a household appliance using a magnet or any other suitable attachment means.  
         [0034]    In use, an activated device is formed by removing a first part  327  comprising a first reactive region  322  and a second part  329  comprising a second reaction region  324  from the tapes  321  and  323  through the perforations  326  and  328 , respectively. The first part  327  and the second part  329  are then combined with the first reactive region  322  and the second reactive region  324  eclipsed and in contact, as explained in detail above.  
         [0035]    Now referring to FIG. 3C, in accordance with alternative embodiments of the invention, a system  340  comprises a plurality of first reactive regions  342  and second reactive regions  344  formed in an alternating fashion on single piece of tape  343 . In use, an activated device is formed from a section  349  comprising a first reactive region  342  and a second reactive region  344  that is separated from the tape  343  through a perforation  348 . The section  349  is then folded over onto itself through a seam  346 , such that the first reactive region  342  and the second reactive region  348  are eclipsed and in contact with each other. While FIG. 3C, shows the first reactive regions  342  and the second reactive regions  344  being formed in an alternating fashion on single piece of tape  343  such that an active device is formed by folding one of the first reactive regions  342  and one of the second reactive regions  344  in an end-to-end fashion, it will be clear to one skilled in the art that a system can alternatively be formed on single piece of tape with first reactive regions and second reactive regions formed in rows, such that an active device is formed by folding one of the first reactive regions  342  and one of the second reactive regions  344  in a side-to-side fashion.  
         [0036]    [0036]FIG. 4A shows a cross sectional view of a timing device  400 , in accordance with the embodiments of the invention. As described previously, the device  400  comprises a lens  405  and a base  401 . The device  400  also comprises an optical medium with one or more fluid layers  411  and  411 ′ and a membrane structure  412  therebetween. The device  400  further comprises a lens coating layer  403  and a reactive material  413  that is capable of reacting with the lens coating layer  403 . To activate the timing device  400 , the membrane structure  403  is ruptured allowing the reactive material  413  to mix with the fluid layers  411  and  411 ′s and react with the lens coating layer  403 , thereby indicating the passage of a duration of time.  
         [0037]    Referring now to FIG. 4B, a timing device  420 , in accordance with further embodiments of the invention, comprises a lens, a metal base structure  421  and an ionic fluid medium  431 , therebetween. The metal base structure  421  is formed from a first metal layer  424  with a first reduction potential and a second metal layer  422  with a second reduction potential that is substantially different from the first metal layer  424 . The device  420  also has metal lens coating layer  423  with a reduction potential that is also substantially different from the first metal layer  424 , but can be the same or nearly the same as the reduction potential of the second metal layer  422 . To actuate the device the metal lens coating layer  423  and the second metal layer  422  are placed in electrical communication with each other. The potential difference between the first metal layer  424  and the second metal layer  422  will drive a current to flow and cause the metal lens coating layer  423  to become depleted over time, and plate out over the first metal layer, thereby indicating the passage of a duration of time.  
         [0038]    In accordance with yet further embodiments of the invention, a timing device  440  is coupled to a circuit  450 , as shown in FIG. 4C. The device  440  comprises a lens  443 , a metal base  441 , a reactive medium  451  and a lens coating layer  445 . The ionic reactive medium  451  is capable of depleting or dissolving the lens coating layer  445 , either chemically or electrochemically as explained previously, when the device  440  is activated. After the device is activated and the lens coating layer  445  is sufficiently depleted or dissolved, the ionic reactive medium  451  provides an electrical path to close the circuit  450  between the leads  447  and  448 . The circuit  450 , in accordance with the embodiments of the invention, comprises a battery  446  and a piezo-electric element that generate an audible signal when the device  440  expires and the circuit  450  is closed.  
         [0039]    In still further embodiments of the invention, a timing device comprises a galvanic cell or an electrolytic cell, wherein one or more electrochemically active materials between a transparent lens and a base, such as metal ions and/or electrodes, are configured to be plated out or depleted and alters the visibility of the base through the lens and indicating the passage of a duration of time. Where a timing device is an electrochemical-based timing device, an actuator switch mechanism comprising electrical contacts can be used to actuate the device. The timing device, in accordance with still further embodiments of the invention, is in electrical communication with a thermosensor (not shown), wherein the thermosensor instructs the actuator switch to close a circuit between electrode elements of a galvanic or electrolytic cell within a range of temperatures.  
         [0040]    Referring to FIG. 5, in accordance with yet further embodiments of the invention, a device comprises a film  500  with a plurality of zones (shown as  1 - 10 ). The zones can be arranged in any geometric pattern, but are preferably arranged in a linear fashion from a first end  510  to a second end  520  of the film  500 . The zones are configured to change color at different rates and, therefore, provide an indication of the passage of a range of times. For example, when each of the zones represents one hour, then the film  500  as shown, indicates the passage of approximately 7 hours. In approximately one more hour, the next zone will change color and indicate the passage of approximately 8 hours.  
         [0041]    Still referring to FIG. 5, each of the zones, in accordance with the embodiments of the invention, comprises a photographic, chemical and/or electro-chemical material, as described in detail above. When the zones (shown as  1  - 10 ) comprise photographic materials, the zones can be made to have different rates of reaction by using photographic materials with different sensitivities to heat, light and/or developer and/or by varying the thickness of diffusion layers deposited over each of the zones, such as described below. In accordance with an embodiment of the invention, the zones are made to have different rates of reaction and/or sensitivity to a developer by pre-treating the zones to a range of different light and/or heat exposures, wherein the zones with longer exposures will develop and change color faster than zones with shorter exposures after being activated.  
         [0042]    Still referring to FIG. 5, when the zones (shown as  1 - 10 ) comprise chemical and/or electro-chemical material(s), as described in detail above and in accordance with the embodiments of the invention, the zones are made to have different rates of reactivity and/or sensitivity. Accordingly, each zone has a different expiration time and indicated passage of a different amount of time and the zones viewed collectively indicate passage of a total time. This embodiment has particular applications for managing inventories of food items in a household refrigerator by indicating how long the food items have been in the refrigerator, regardless of whether or not the food items have spoiled or aged past a freshness date.  
         [0043]    [0043]FIG. 6 is a cross-sectional representation of a section of timing film  600 , in accordance with the embodiments of the invention. The section of timing film  600  is formed by coating or depositing a photographic layer  605 , which can include silver, silver halide, gelatin, cellulose, fatty acids, developers or combinations thereof, onto a base structure  603 . The base structure  603  is preferably formed from a polymeric material, such as polyester, and can also include an adhesive layer (not shown) for attaching the section of timing film  600  to a consumer article (also not shown).  
         [0044]    Still referring to FIG. 6, the section of film  600 , in accordance with the embodiments of the invention, further comprises a diffusion layer  615  comprising a diffusion material and a developer layer  611  comprising a developer. The diffusion material is any material that will allow the developer in the developer layer  611  to migrate to the photographic layer  605  causing the photographic layer  605  to change color or darken and indicate the passage of time. Suitable diffusion materials include, but are not limited to, gelatin, cellulose and combinations thereof.  
         [0045]    In accordance with still further embodiments of the invention, the section of film  600  further comprises a barrier layer  613  that can be pulled out or removed to activate the device and allow the developer layer  611  to diffuse through the layer  615  and cause the photographic layer  605  to change color or darken and indicate the passage of time. Alternatively, the photographic layer  605  and the developer layer  611  are formed as separate parts that can be brought together to activate the device, as explained in detail above with reference to FIGS.  3 A-C.  
         [0046]    The current invention has applications for marking when any number of different events need to take place and/or for timing the duration of any number of different events. For example, the timing device of the present invention has applications for indicating when perishable materials have expired and need to be thrown out, indicating the age of inventory and managing when the inventory needs to be rotated, tracking a deadline and a host of other time and/or temperature dependent events. One advantage of the present invention is that the timing device can be fabricated in two or more reactive parts, wherein the device is not activated, or sensitive to the environment (such as temperature), until the parts are coupled together, as explained in detail above. Accordingly, the shelf life of the timing device prior to use is enhanced and the sensitivity of the device to environmental conditions prior to use is reduced.  
         [0047]    While the present invention has been described in terms of specific embodiments incorporating details to facilitate the understanding of the principles of construction and operation of the invention. As such, references, herein, to specific embodiments and details thereof are not intended to limit the scope of the claims appended hereto. It will be apparent to those skilled in the art that modifications can be made in the embodiment chosen for illustration without departing from the spirit and scope of the invention.