Abstract:
A serving tray comprised of at least one synthetic material and an insert which provides a non-slip top surface of the serving tray. The textured relief is preferably made of thermoplastic polyurethane (TPU) which allows a glass or other item to be placed on the serving tray without the item sliding or slipping while the tray is in motion. As the tray is being fabricated, the TPU is mechanically bonded with the top surface of the tray while a textured relief is simultaneously defined into the top surface. The textured relief provides adequate frictional force to an item being placed on the tray so as to substantially prevent its lateral movement. The tray also includes an inner support structure disposed on its inner surface. The inner support structure provides an upward facing edge which allows a plurality of trays to be easily and efficiently stacked or nested on one another.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a Continuation-in-Part application of non-provisional patent application entitled, “Serving Tray Incorporating Thermoplastic Polyurethane and Methods for Manufacturing the Same,” Ser. No. 15/153,274, filed on May 12, 2016, under 35 USC 120, which is incorporated herein by reference. 
     
    
     BACKGROUND 
     Field of the Technology 
       [0002]    The invention relates to the field of plastic trays and methods for manufacturing the same. 
       Description of the Prior Art 
       [0003]    Serving trays have long been used in a variety of settings including cafeterias, hospitals, hotels, bars, and restaurants. Many of these serving trays are comprised of plastic or plastic composites including polyester resin and other variations of polyethylene. Other trays may comprise one or more layers of fiberglass strand mats blended into their structure for increased structural strength and durability. 
         [0004]    Many trays currently in use comprise a textured, upward facing surface which aides in the prevention of items which are placed on the tray from sliding or moving about when the tray is moved or carried. Typically, a textured surface is formed or defined in the top surface of the tray itself and is usually in the form of a series of ridges or protrusions which interact with a bottom surface of an item which is placed on the tray. Other trays do not comprise any textured surface at all but instead comprise a mat made of rubber, cork, or other suitable material which is then laid directly and/or adhered onto the tray. The textured surface or mat then serves to help maintain any item placed on the tray in a fixed position. 
         [0005]    While serving trays with raised or textured surfaces have helped reduce instances of items placed on trays such as plates, glasses, and other dishware from slipping and/or breaking, they are not completely fool proof and can still lead to unnecessary accidents and increased costs. Condensation which has formed on the outside surfaces of glasses can run down into the raised textured surface of the tray and make them slick thus increasing the chances that a glass may slide or tip over when the tray is being moved. Rubber and cork insert layers can break down over time after repeated exposure to moisture which reduces the overall durability and effective lifetime of the tray, forcing the user to discard or refurbish the tray at greater expense. 
         [0006]    What is needed is a serving tray comprising a textured surface that is not subject to the limitations of the previous art and which is capable of sustaining a glass or other object at an upright orientation regardless of condensation or other environmental factors. Additionally, a plurality of methods of manufacturing are needed in order to produce such a tray. 
       BRIEF SUMMARY 
       [0007]    The current invention is a serving tray which includes a top surface, a bottom surface disposed on an opposing side of the top surface, and a raised edge disposed about the top surface. The tray also includes an inner support structure disposed circumferentially around the top surface. Disposed within the raised edge are at least two elongated lips, while the top surface has a textured relief defined into it. Both the top surface and the bottom surface are made of at least one synthetic material, while the textured relief is made from an insert that is integrally bonded with the at least one synthetic material. 
         [0008]    In one embodiment, the insert of the tray which is integrally bonded with the at least one synthetic material is specifically made of a sheet of thermoplastic polyurethane (TPU). 
         [0009]    In another embodiment, the inner support structure of the tray includes a protrusion in its surface which provides an upward facing edge around the circumference of the top surface of the tray. 
         [0010]    In yet another embodiment, the inner support structure of the tray is disposed on the raised edge and above the top surface. 
         [0011]    In still a further embodiment, the tray is made from a number of synthetic layers including at least two layers of randomly distributed and continuous glass fiber filament sheets, at least two layers of crisscrossed interlocking glass fiber sheets with a chemical binder, and an interstitial layer of polycarbonate resin. 
         [0012]    In one embodiment, the tray further includes a shaped smooth boundary portion that is located between the textured surface and the inner support structure on the raised edge on the top surface. 
         [0013]    In yet another embodiment, the textured relief includes a number of raised protrusions and a number of recessed indentations that are asymmetrically disposed over the top surface. 
         [0014]    The invention also includes an improvement in a method of making a friction enhanced tray in a compression molding apparatus. The method includes placing an insert on top of a lower tool portion of the compression molding apparatus, layering at least two layers of randomly distributed and continuous glass fiber filament sheets on top of the insert, and then layering at least two layers of crisscrossed interlocking glass fiber sheets with a chemical binder on top of the insert. Next, an interstitial layer of polycarbonate resin is disposed between the at least two layers of crisscrossed interlocking glass fiber sheets with a chemical binder. The insert, the least two layers of randomly distributed and continuous glass fiber filament sheets, the at least two layers of crisscrossed interlocking glass fiber sheets with a chemical binder, and the interstitial layer of polycarbonate resin are then compressed against the lower tool portion of the compression molding apparatus and which also defines an inner support structure in the friction enhanced tray. Finally, a textured relief is defined within the insert. 
         [0015]    In one embodiment, the method step of defining the textured relief within the insert includes impressing a chemically etched mold surface disposed on the lower tool portion into a surface of the insert. 
         [0016]    In another embodiment, the method step of compressing the insert and defining an inner support structure in the friction enhanced tray specifically includes defining the inner support structure above the insert on a raised edge that is disposed around the circumference of the insert. Defining the inner support structure above the insert on a raised edge that is disposed around the circumference of the insert further includes defining a protrusion along the length of the inner support structure. 
         [0017]    In yet another embodiment, the method also includes defining a shaped smooth boundary portion that is disposed around the textured relief defined in the insert and beneath the inner support structure. 
         [0018]    In a further embodiment, the method step of placing the insert on top of a lower tool portion of the compression molding apparatus specifically includes placing a sheet of thermoplastic polyurethane (TPU) on top of the lower tool portion of the compression molding apparatus. 
         [0019]    Finally, in a further embodiment the method step of defining a textured relief within the insert includes asymmetrically defining a plurality of raised protrusions and a plurality of recessed indentations into a surface of the insert. 
         [0020]    The invention also includes an improvement in a method of making a friction enhanced tray in an injection molding apparatus. The method includes placing an insert on a first half of a mold of the injection molding apparatus, enclosing the insert by bringing a second half of the mold against the first half of the mold, the first and second halves of the mold forming a completed mold tool, and then injecting a liquid interstitial resin into the completed mold tool. Next, a tray is formed around the insert within the completed mold tool. At the same time, an inner support structure is formed in the tray while a textured relief is defined within a surface of the insert. 
         [0021]    In one embodiment, the method step of defining the textured relief within a surface of the insert specifically includes impressing a mold surface disposed on the first half of the mold into the surface of the insert. 
         [0022]    In another embodiment, the method step of forming an inner support structure in the tray includes forming the inner support structure above the insert on a raised edge that is disposed around the circumference of the insert. This embodiment further includes where forming the inner support structure above the insert on a raised edge that is disposed around the circumference of the insert includes forming a protrusion along the length of the inner support structure. 
         [0023]    In another embodiment, the method further includes defining a shaped smooth boundary portion disposed around the textured relief defined in the surface of the insert and beneath the inner support structure. 
         [0024]    In yet another embodiment, the method step of placing an insert on a first half of a mold of the injection molding apparatus specifically includes placing a sheet of thermoplastic polyurethane (TPU) on the first half of the mold of the injection molding apparatus. 
         [0025]    While the apparatus and method has or will be described for the sake of grammatical fluidity with functional explanations, it is to be expressly understood that the claims, unless expressly formulated under 35 USC 112, are not to be construed as necessarily limited in any way by the construction of “means” or “steps” limitations, but are to be accorded the full scope of the meaning and equivalents of the definition provided by the claims under the judicial doctrine of equivalents, and in the case where the claims are expressly formulated under 35 USC 112 are to be accorded full statutory equivalents under 35 USC 112. The disclosure can be better visualized by turning now to the following drawings wherein like elements are referenced by like numerals. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIG. 1  is a perspective view of a serving tray of the current invention. 
           [0027]      FIG. 2  is a top view of the serving tray seen in  FIG. 1 . 
           [0028]      FIG. 3  is a bottom view of the serving tray seen in  FIG. 1 . 
           [0029]      FIG. 4  is a block diagram showing of a compression molding device used to fabricate the serving tray seen in  FIG. 1 . 
           [0030]      FIG. 5  is a block diagram showing the configuration of an injection molding device used to fabricate the serving tray seen in  FIG. 1 . 
           [0031]      FIG. 6  is a side elevational view of the serving tray seen in  FIG. 1 . 
           [0032]      FIG. 7A  is a cross sectional view of the serving tray seen in  FIG. 6 . 
           [0033]      FIG. 7B  is a magnified cross sectional view of surface of the serving tray seen in  FIG. 7A . 
           [0034]      FIG. 8  is a side elevational view of a plurality of serving trays seen in  FIGS. 1 and 6  when stacked or nested within one another. 
           [0035]      FIG. 9A  is a cross sectional view of the plurality of stacked or nested serving trays seen in  FIG. 8 . 
           [0036]      FIG. 9B  is a magnified cross sectional view of the stacked or nested surfaces of the plurality of serving trays seen in  FIG. 9A . 
       
    
    
       [0037]    The disclosure and its various embodiments can now be better understood by turning to the following detailed description of the preferred embodiments which are presented as illustrated examples of the embodiments defined in the claims. It is expressly understood that the embodiments as defined by the claims may be broader than the illustrated embodiments described below. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0038]    The current invention comprises a manufactured serving tray which may be seen in  FIGS. 1-3  and which is denoted generally under reference numeral  10 . As seen in  FIGS. 1-3 , the tray  10  is substantially circular shaped, however other shapes known in the art such as rectangles, squares, and the like may be used without departing from the original spirit and scope of the invention. The tray  10  comprises a top surface  12  which is surrounded circumferentially by a raised edge  14 . The raised edge  14  begins at the outer edge of the top surface  12  and is disposed at an angle relative to the top surface  12  which is substantially horizontal or flat. The raised edge  14  further comprises at least two elongated lips  16  which are diametrically disposed across the tray  10 . Each lip  16  represents a bulge or increased surface area portion compared to the rest of the raised edge  14  as best seen in the top down view of  FIG. 2  that is orientated substantially perpendicular to the inclined orientation of the raised edge  14 . The tray  10  also comprises a bottom surface  18  as seen in  FIG. 3 . The bottom surface  18  further comprises a plurality of feet  20  disposed in a symmetrical pattern around the circumference of the bottom surface  18 . The plurality of feet  20  help keep the tray  10  in a fixed position when placed on a table or other horizontal surface as is known in the art. 
         [0039]    As best seen in  FIG. 2 , the top surface  12  is substantially round or circular shaped, while the lips  16  help form or stretch the overall shape of the raised edge  14  a substantially oval or oblong shape, thus creating an oval or oblong shaped upper profile of the tray and a circular shaped lower profile of the tray. The oblong shaped upper profile of the tray  10  comprising the lips  16  allows a user to easily grip and carry the tray  10  when glassware and other items on placed on its top surface  12  while the circular lower profile of the tray  10  allows multiple trays to be stacked or nested within one another without regard to each successive tray&#39;s 10 orientation with regard to each other. In other words, when a second tray is placed on top of the first tray  10 , the circular lower profile of the second tray fits easily and snuggly on top of the top surface  12  and within the confines of the raised edge  14  of the first tray  10  regardless of which direction the lips  16  are currently orientated in. This therefore allows a plurality of trays  10  to be quickly and efficiently stacked upon each other when the trays  10  are not in use or when held in storage. 
         [0040]    The tray  10  further comprises a textured relief  22  defined into the top surface  12 . The textured relief  22  preferably comprises a plurality or sequence of raised ridges or protrusions and a corresponding plurality of recessed indentations or depressions distributed about the top surface  12  in an asymmetrical pattern, however other similar or equivalent relief patterns now known or later devised may be used without significantly departing from the original spirit and scope of the invention. The textured relief  22  is configured to dramatically increase the coefficient of friction of the top surface  12  so that when glassware or other items are placed upon it, the item will remain frictionally engaged and motionless on the top surface even when the tray  10  is titled at an angle of up to and including 45 degrees relative to the horizontal. The textured relief  22  is defined across the substantial majority of the top surface  12 , however as best seen in  FIG. 2 , the textured relief  22  ends at a specified distance away from the beginning of the raised edge  14 , thus leaving a shaped smooth boundary portion  24  disposed about a circumference of the tray  10  between the relief portion  22  and the raised edge  14 . 
         [0041]    As also seen in  FIGS. 1 and 2 , the tray  10  further comprises an inner support structure  60 . The inner support structure  60  is a substantially ring or annular shaped protrusion that is elevated or raised with respect to the surface of the raised edge  14 . The inner support structure  60  is disposed along the surface of the raised edge  14  and above the top surface  12  and smooth boundary portion  24 . As best seen in  FIG. 2 , the inner support structure  60  is disposed about the entire inner circumference of the tray  10 . 
         [0042]    The majority of the tray  10  is preferably comprised of successive layers of plastic or plastic composites as will be detailed further below, however disposed at or on the top surface  12  is preferably an insert  26  comprising at least one layer of thermoplastic polyurethane (TPU). As is known in the art, TPU is part of a class of polyurethane plastics which has a high shear strength and a high elasticity, making it ideal for being used in a molding process. TPU is also highly resistant to liquids, oil, and grease, thus further making it suitable for use in the food and beverage industry where contact with various liquids or oils is commonplace. When an item such as a glass, cup, or other dishware is placed on the tray  10  that comprises an insert  26  comprised of TPU that is integrally bonded with the top surface  12 , the item will remain upright on the tray  10  even when the tray  10  is tilted at an angle of up to 45 degrees from the horizontal. Because of the ability of TPU to resist liquid, the tray  10  comprising a TPU top surface  12  will also maintain the item in an upright position even if that item is wet, condensation has formed on the item, or if liquid has been spilled on the top surface  12  of the tray  10 . 
         [0043]    Greater detail of the inner support structure  60  may be seen in  FIGS. 7A and 7B . The inner support structure  60  is disposed about the circumference of the tray  10  at a constant elevation above the top surface  12  and along the inner surface of the raised edge  14 . As best seen in the magnified view of  FIG. 7B , the inner support structure  60  specifically comprises a protrusion or bump  62  which provides a localized increased thickness to the raised edge  14 , thus creating an upward facing edge or surface around the inner circumference of the serving area of the tray  10 . 
         [0044]    Having an inner support structure  60  aides in the ability of a plurality of trays  10  to be nested or stacked as seen in  FIGS. 8, 9A, and 9B .  FIGS. 8 and 9A  show that when a plurality of trays  10  are stacked vertically on one another, each subsequent tray  10  is placed within the tray  10  disposed directly beneath it, specifically with the bottom surface  18  of the nested tray  10  being disposed within the enclosed circumference formed by the raised edge  14  of the tray  10  beneath it. The magnified cross section of  FIG. 9B  shows that when the bottom surface  18  of a tray  10  to be stacked is placed into a tray  10  disposed beneath it, it comes to rest on top of the inner support structure  60 . More specifically, the bottom surface  18  rests upon the upward facing surface of the protrusion  62 . Because the inner support structure  60  is disposed around the circumference of the tray  10 , any subsequent tray  10  which is nested within it will be maintained at a constant elevation that is above that of the top surface  12  of the bottom tray  10 . The process may be repeated for each subsequently nested tray  10  with the bottom surface  18  of each tray  10  resting on the inner support structure  60  of the tray  10  disposed directly beneath it so that a stack is formed as seen in  FIGS. 8 and 9A . Having each tray  10  maintained at a raised elevation with respect to the tray  10  beneath it when in a stacked configuration allows the plurality of trays  10  to be easily stacked in a stable position. Additionally, because each tray  10  is maintained at a fixed elevated position, the lips  16  of each tray  10  are also maintained at a fixed elevated position with respect to one another as seen in  FIG. 9B , thus allowing a user to easily and quickly grab a single tray  10  by grabbing the corresponding lip  16  and lifting upwards. The inner support structure  60  of the current tray  10  thus prevents the plurality of trays  10  from becoming wedged or stuck together when placed in a stacked configuration. 
         [0045]    In one embodiment, the tray  10  may be manufactured according to a compression wet molding process. In this embodiment as seen in  FIG. 4 , an insert  26  comprising a sheet of TPU is placed on a lower tool  28  of a compression manufacturing device shown generally as reference numeral  30 . The TPU sheet  26  preferably comprises a durometer value of 65A to 85D and an overall thickness of 0.005 in. to 0.060 in., however other durometer or thickness values may be used without significantly departing from the overall scope and spirit of the claim. A first surmat or fiberglass veil  32  is placed over the TPU sheet  26 , followed by a first chopped strand mat  34 . A portion of liquid state polyester resin  36  is then evenly or symmetrically distributed over the first chopped strand mat  34 . Next, a second chopped strand mat  34 ′ is placed over the now resin covered first chopped strand mat  34 . Finally, a second surmat or fiberglass veil  32 ′ is layered on the second chopped strand mat  34 ′, thus completing a fully formed stack or sandwich  40  which is used to form the tray  10 . Alternatively, the TPU sheet  26  may be placed directly on the lower tool  28  while the sandwich  40  comprising the first and second surmat  32 ,  32 ′, the first and second chopped strand mat  34 ,  34 ′ and the resin  36  is formed at a separate location. The resin  36  is preferably an interstitial resin, meaning the resin  36  is allowed to flow and completely fill in the volume defined between the first and second chopped strand mats  34 ,  34 ′. The formed sandwich  40  as single unit may then be moved to the compression manufacturing device  30  and placed on the TPU sheet  26 . After all the layers of the tray  10  are in place, the compression manufacturing device  30  is activated and an upper tool  38  moves downward and presses the sandwich  40  and TPU sheet  26  against the lower tool  38 , compressing the layers into a shape as dictated by the shape of the lower and upper tools  28 ,  38 . As the layers of the tray  10  are being compressed, each layer of the tray are pressed together and a mechanical bond is formed between each subsequent layer, including the TPU sheet  26  which becomes an integral part of the structure of the tray  10 . At the same time, the lower tool  28  which comprises a chemically etched mold for the top surface  12  of the tray  12 , presses into the TPU sheet  26  deep enough to sufficiently form the textured relief  22 , preferably to a depth range from 0.002 in. to 0.025 in. The mold etched into the surface of the lower tool  28  is configured so as to form the smooth portion  24  and the support structure  60 . Having a smooth portion  24  located on the top surface  12  of the tray  10  is critical since it creates a buffer zone disposed between the support structure  60  and the textured relief  22 . Resin  36  which leaks or is pushed out by the compression process is stopped by the mold of the lower tool  28  which prevents the resin  36  from interfering with the fabrication of the textured relief  22 . If resin  36  is allowed to seep onto the top surface  12  as the textured relief  22  is being formed, the resin  36  will be compressed into the TPU sheet  26  and the various ridges, protrusions, indentations, and depressions which comprise the textured relief  22  will be filled in or covered by the resin  36 , thus effectively spoiling the desired friction profile of the textured relief  22 . Once compression is complete, the upper tool  38  is drawn away from the lower tool  28  and the now fully formed tray  10  may be lifted up off the lower tool  28  and removed from the compression manufacturing device  30 . A user may then repeat the process and create additional trays  10  as needed. 
         [0046]    The first and second chopped strand mat  34 ,  34 ′ are preferably comprised of crisscrossed, interlocking glass fibers with a chemical binder which holds the glass fibers together in sheet form. Depending the density of the glass fibers, each chopped strand mat  34 ,  34 ′ may have a weight of 1.25, 1.5, 1.75, or 2 ounces per square foot. In contrast, the first and second surmat  32 ,  32 ′ are comprised of continuous glass fiber filaments that are randomly distributed and bonded together with a specially formulated resin or binder. The first and second surmats  32 ,  32 ′ bring the resin  36  to the surface of the tray  10  and improves the overall surface appearance of the tray  10 . Each surmat  32 ,  32  preferably has a thickness that is between 7 mm/2.6 grams per square foot to 30 mm/9.7 grams per square foot. Both the chopped strand mats  34 ,  34 ′ and the surmats  32 ,  32 ′ each comprise sizing which is a silane coupling agent. The sizing helps form the necessary bond between the fiber glass filaments of the surmats  32 ,  32 ′ and chopped strand mats  34 ,  34 ′ with the resin  36  in order to produce the tray  10 . 
         [0047]    While the insert  26  has been described above as comprising a sheet of TPU which is used as the top most additive added to the composition of the tray  10 , similar or additional materials may also be used without departing from the original spirit and scope of the invention. For example, the insert may comprise other materials such as rubber, silicone, paper coated with polyurethane, a styrene acrylonitrile (SAN) sheet coated with polyurethane, or a combination thereof. 
         [0048]    Similarly, while epoxy resins has been described above as being used as forming the main composition of the tray  10 , this is meant to be for illustrative purposes only. Similar or additional substances other than what is disclosed above may also be used without departing from the original spirit and scope of the invention, for example thermoset matrix resins, vinyl ester, or unsaturated polyester. More specifically, the type of unsaturated polyester used may include but is not limited to bispheon A fumerate, DCPD-modified, fire-retardant, isophthalic, low-VOC or no VOC, orthophthalic, or terephthalic unsaturated polyesters, or a combination thereof. 
         [0049]    In another embodiment, the tray  10  may be fabricated according to an injection molding technique. In this embodiment as seen in  FIG. 5 , a sheet of TPU  26  is placed on a first half  42  of a mold of an injection molding device shown generally as reference numeral  50 . The mold then closes by bringing the second half  44  of the mold against the first half  42 . At the same time, plastic or plastic composite pellets are delivered from a hopper  46  into a heated barrel  48 . The barrel  48  heats the pellets to create a liquid or interstitial polymer resin from the material which comprised the pellets and delivers the resin to the mold via an injection nozzle. The resin then flows into the mold and forms a tray  10  around the TPU sheet  26  as determined by the specific contours and shape of the mold itself. The first half  42  of the mold, like the lower tool  28  as disclosed above, is chemically etched to form the textured relief  22  on the top surface  12  of the tray  12 . The combined pressure of the first and second halves  42 ,  44  presses into the TPU sheet  26  deep enough to sufficiently form the textured relief  22  and incorporate the TPU sheet  26  into the integral structure of the tray  10 . The etched surface of the first half  42  of the tool is configured so as to form the smooth portion  24  and support structure  60  seen in  FIG. 2 . Once the mold has been sufficiently filled with resin, the mold is allowed to cool. The mold is then opened by pulling the second half  44  away from the first half  42 . The now fully formed tray  10  is then ejected or otherwise removed from the mold and the entire process is allowed to repeat itself as needed. 
         [0050]    While the insert  26  has been described above as comprising a TPU sheet which is used as the additive added to the mold before the resin is injected into the mold, similar or additional materials may also be used without departing from the original spirit and scope of the invention. For example, the insert  26  may comprise other materials such as rubber, silicone, paper coated with polyurethane, a styrene acrylonitrile (SAN) sheet coated with polyurethane, or combinations thereof. 
         [0051]    Similarly, while plastic pellets have been described above as being heated to create a polymer resin which is injected into the mold to form the tray  10 , this is meant to be for illustrative purposes only. Similar or additional substances other than what is disclosed above may also be used without departing from the original spirit and scope of the invention. For example, polycarbonate, copolymer, polypropylene, or polyethylene resins may also be used. Additionally, other substances such as nylon, acrylic back up (ABU), TPU, or a combination thereof can also be used to form the tray  10  and achieve a substantially similar result. 
         [0052]    Many alterations and modifications may be made by those having ordinary skill in the art without departing from the spirit and scope of the embodiments. Therefore, it must be understood that the illustrated embodiment has been set forth only for the purposes of example and that it should not be taken as limiting the embodiments as defined by the following embodiments and its various embodiments. 
         [0053]    Therefore, it must be understood that the illustrated embodiment has been set forth only for the purposes of example and that it should not be taken as limiting the embodiments as defined by the following claims. For example, notwithstanding the fact that the elements of a claim are set forth below in a certain combination, it must be expressly understood that the embodiments includes other combinations of fewer, more or different elements, which are disclosed in above even when not initially claimed in such combinations. A teaching that two elements are combined in a claimed combination is further to be understood as also allowing for a claimed combination in which the two elements are not combined with each other, but may be used alone or combined in other combinations. The excision of any disclosed element of the embodiments is explicitly contemplated as within the scope of the embodiments. 
         [0054]    The words used in this specification to describe the various embodiments are to be understood not only in the sense of their commonly defined meanings, but to include by special definition in this specification structure, material or acts beyond the scope of the commonly defined meanings. Thus if an element can be understood in the context of this specification as including more than one meaning, then its use in a claim must be understood as being generic to all possible meanings supported by the specification and by the word itself. 
         [0055]    The definitions of the words or elements of the following claims are, therefore, defined in this specification to include not only the combination of elements which are literally set forth, but all equivalent structure, material or acts for performing substantially the same function in substantially the same way to obtain substantially the same result. In this sense it is therefore contemplated that an equivalent substitution of two or more elements may be made for any one of the elements in the claims below or that a single element may be substituted for two or more elements in a claim. Although elements may be described above as acting in certain combinations and even initially claimed as such, it is to be expressly understood that one or more elements from a claimed combination can in some cases be excised from the combination and that the claimed combination may be directed to a subcombination or variation of a subcombination. 
         [0056]    Insubstantial changes from the claimed subject matter as viewed by a person with ordinary skill in the art, now known or later devised, are expressly contemplated as being equivalently within the scope of the claims. Therefore, obvious substitutions now or later known to one with ordinary skill in the art are defined to be within the scope of the defined elements. 
         [0057]    The claims are thus to be understood to include what is specifically illustrated and described above, what is conceptionally equivalent, what can be obviously substituted and also what essentially incorporates the essential idea of the embodiments.