Abstract:
A method of constructing a liquid crystal display element or similar article of manufacture includes providing a first transparent substrate bondable to a second transparent substrate. The second transparent substrate has a plurality of vias passing through opposing active faces. A dispensing technique is used to fill the vias void-free with an optical grade adhesive material to form the LCD element.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    The present application is related to U.S. application Ser. No. ______ (Docket 81525), filed ______, by Kenneth M. Fallon, et al., and entitled, “Liquid Crystal Display Element;” U.S. application Ser. No. ______ (Docket 83499), filed ______, by Kenneth M. Fallon, et al., and entitled, “Liquid Crystal Display And Method Of Making Same;” U.S. application Ser. No. ______ (Docket 83500), filed ______, by Kenneth M. Fallon, et al., and entitled, “Apparatus For Introducing A Fluid Into Vias Formed In A Liquid Crystal Display Element;” and U.S. application Ser. No. ______ (Docket 83501), filed ______, by Kenneth M. Fallon, et al., and entitled, “Method Of Delivering Fluid Into Constricted Openings Free Of Voids.” 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The invention relates generally to the field of liquid crystal displays (LCDs). More particularly, the invention concerns a liquid crystal display element, a liquid crystal display and method of making same in which a select one of two bonded substrate components has a plurality of vias filled with an optical grade adhesive in a manner to eliminate voids in the vias thereby substantially eliminating light scattering during LCD operations.  
         BACKGROUND OF THE INVENTION  
         [0003]    Conventional liquid crystal displays are formed by bonding two substantially planar substrates, commonly referred to as a panel electrode, and a drive or signal substrate, together with a gap between them and then injecting a liquid crystal in the gap. Electrical connectivity between the drive and panel substrates is typically achieved with an anisotropic conductive film that connects wiring terminals on a flexible polyimide drive substrate with transparent electrode terminals formed on of indium tin oxide (ITO) is deposited on both the panel and drive substrates forming a patterned ITO layer on the substrate(s). After forming the patterned ITO layer, the two glass substrates are then bonded together with a known gap therebetween. To complete the manufacturing process of the LCD, a liquid crystal material is then vacuum filled in the gap of the bonded substrates thereby forming an active liquid crystal display.  
           [0004]    U.S. Pat. No. 5,629,787, entitled “Method For Producing An LCD By Pressing The Substrates” by Tsubota et al., May 13, 1997, is illustrative of an existing process for making a typical liquid crystal display in which a spacer is used to determine the gap between the transparent substrates. Moreover, an ITO layer is coated only on one active surface of the transparent substrate. This reference, however, does not teach the presence of a plurality of adhesive filled, void-free vias formed in one of the substrates.  
           [0005]    Canadian Patent Application No. 2,279,780, entitled “Light Density Control With LCD Arrangement” by Kraft, et al. filed Aug. 9, 1999, discloses a LCD arrangement with improved exposure control in a photo finishing environment in which multiple picture elements (pixels) associated with electrodes are positioned on bonded transparent plates and feed conductors to the electrodes feed control signals thereto. Referring to FIG. 1, a typical prior art LCD display element  1  contains vias  2  or feed throughs in a transparent substrate  3  and patterning of an ITO layer  6  on opposed active surfaces  4  and  5 . Although the reference teaches vias  2  filled with an adhesive material layer  9  in the transparent substrate  3 , the reference clearly recognizes that air bubbles or voids  8  exist in the adhesive material  9  filling the vias  2  that necessitates vacuum removal. Moreover, the reference does not recognize controlling the height and thickness of the adhesive material  9  as important factors in bonding a deck plate  7  to a transparent substrate  3  with an ITO coating layer  6  applied to the active surfaces  4 ,  5  or filling the vias  2 .  
           [0006]    U.S. Pat. No.  6 , 061 , 105 , entitled “LCD With Via Connections Connecting The Data Line To A Conducting Line Both Before And Beyond The Sealing Material” by Nakagawa, May 9, 2000, discloses a liquid crystal display device that can eliminate an electrostatic discharge (ESD) problem resulting from a high dielectric constant filler that is appropriate for improved shape stability of a sealing material. While this reference is generally believed to teach a good solution to the electrostatic discharge problems encountered in the LCD display fabrication process, it does not teach or suggest adhesive filled, void-free vias formed in one of the substrates.  
           [0007]    U.S. Pat. No. 6,061,105 discloses using vias connections in thin film transistors (TFT) connections. This reference, however, does not present vias in the transparent substrate that feed ITO from one active surface to an opposed active surface of the transparent substrate. According to the prior art reference, the vias are formed in the seal area and outside the active pixels area of the display. Thus, the reference does not contemplate the use of optical grade adhesives nor the need to maintain transparency in the active area. Hence this reference shows no appreciation for Applicants&#39; problem or proposed solution.  
           [0008]    Therefore, a need persists in the art for a liquid crystal display element and method of making same in which vias are formed in a substrate and then specially filled with an optical grade adhesive. The adhesive material filling the vias are virtually free of voids which substantially eliminates light scatter in an operating LCD, for instance, in a photofinishing application.  
         SUMMARY OF THE INVENTION  
         [0009]    It is, therefore, an object of the invention to provide a method of constructing a liquid crystal display (LCD) element having vias formed in one of two transparent substrates filled with an optical grade adhesive material in a manner that resists the scatter of light.  
           [0010]    Another object of the invention is to provide such a method in which the vias in the aforementioned LCD element are filled in a manner to substantially eliminate the presence of voids in the optical grade adhesive materials filling the vias.  
           [0011]    The present invention is directed to overcoming one or more of the problems set forth above. Briefly summarized, according to one aspect of the present invention, a method of constructing a liquid crystal display element includes the step of providing a first transparent substrate having a first surface and an opposed second surface, said first surface being provided with a first ultra-violet protective layer; providing a second transparent substrate for fixedly attaching to said first transparent substrate with a predetermined gap therebetween, said second transparent substrate having a first active surface for bonding with said second surface of said first transparent substrate, and a second active surface opposite said first active surface, and wherein said second transparent substrate being provided with a plurality of vias passing between said first active surface and said second active surface to facilitate electrical continuity between said first active surface and said second active surface; controllably dispensing an optical grade adhesive material between said first transparent substrate and said second transparent substrate so as to fill each one of said plurality of vias in said second transparent substrate to a predetermined plug height; and, curing said optical grade adhesive material so as to bond said second surface of said first transparent substrate to said first active surface of said second transparent substrate thereby forming a liquid crystal display element.  
           [0012]    Thus, the present invention has numerous advantageous effects over prior art developments, including: air bubble free or void-free adhesive material filling vias formed in the second transparent substrate; air bubble free or void-free adhesive material bonding the second transparent substrate and the first transparent substrate; thickness controlled adhesive material levels dispensed into vias; efficient vias fill associated with controlled first transparent substrate to second transparent substrate gap width; fewer process steps in the LCD subassembly process; and, substantially simple process for locating the first transparent substrate in the LCD element. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    The above and other objects, features, and advantages of the present invention will become more apparent when taken in conjunction with the following description and drawings wherein identical reference numerals have been used, where possible, to designate identical features that are common to the figures, and wherein:  
         [0014]    [0014]FIG. 1 is a prior art liquid crystal display element having a void in an adhesive filled vias;  
         [0015]    [0015]FIG. 2 is a perspective view of the liquid crystal display element of the invention;  
         [0016]    [0016]FIG. 3 is a cross-sectional view of the first transparent substrate of the invention;  
         [0017]    [0017]FIG. 4 is a cross-sectional view of the second transparent substrate showing the vias passing through the active surfaces; and,  
         [0018]    [0018]FIG. 5 is a sectional view of the apparatus used for filling vias void-free in the second transparent substrate;  
         [0019]    [0019]FIG. 6 is a partial cross sectional view of the signal plate having vias with excessive optical grade epoxy material therein; and,  
         [0020]    [0020]FIG. 7 is a partial cross sectional view of the signal plate having vias deficient in optical grade material therein.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]    Turning now to the drawings, and particularly to FIGS. 2, 3, and  4 , the liquid crystal display (LCD) element  10  or components thereof made in accordance with the method of the invention is illustrated. According to FIGS. 3 and 4, liquid crystal display element  10  is generally defined as having a first transparent substrate, or alternatively deck plate,  12  fixedly bonded to a second transparent substrate, or alternatively signal plate,  18 . According to FIG. 2, among other things, deck plate  12  provides barrier protection for an indium tin oxide (ITO) coating layer  32  deposited on active surface  20  of signal plate  18 .  
         [0022]    Referring to FIG. 2, the ITO coating layer  32  provides electrical continuity between active surfaces  20 ,  22  through vias  30 . It should be appreciated that existing LCD panels teach an ITO coating layer  32  deposited only on one active surface of the signal plate in contradistinction to the present LCD element having an ITO coating layer  32  deposited on opposing active surfaces  20 ,  22  of signal plate  18 .  
         [0023]    Referring to FIGS. 2 and 4, important to the present invention, a plurality of through holes, commonly referred to as vias  30 , is formed in the signal plate  18 . As indicated, vias  30  provide electrical continuity paths between the opposing active surfaces  20 ,  22  of the signal plate  18 , as described in greater details below. Skilled artisans in the field of LCD manufacturing will appreciate that the present invention necessitates solving a range of new and challenging problems never before presented in traditional LCD manufacturing. To maintain transparency of the signal plate  18 , it was discovered that vias  30  then had to be filled with an optical grade adhesive material  34  (described below) free of air bubbles or voids so as to prevent light scattering from the functioning LCD (compare FIGS. 1 and 2). Moreover, it was discovered that the adhesive material  34  provides the unexpected benefit of further protecting the ITO coating layer  32  bonding the deck plate  12  to the signal plate  18 .  
         [0024]    Referring to FIGS. 2 and 3, by carefully controlling gap  11  separating the deck plate  12  and active surface  20  of signal plate  18 , we were able to facilitate capillary action that efficiently wicked the optical grade adhesive material  34  into the vias  30  formed in signal plate  18 . Spacers  28 , such as standoffs or shims, affixed to deck plate  12  is preferably used to control the spacing between deck plate  12  and signal plate  18 . As shown in FIG. 5, surface tension and the presence of a cavity  70  in the assembly fixture  60  prohibit the optical grade adhesive material  34  from wicking out onto second active surface (alternatively referred to as the pixel side of the LCD element)  22  of signal plate  18 . Second active surface  22  of signal plate  18  is then coated with a first polyimide alignment layer  38  which aligns the LCD medium  42  (typically a liquid crystal material formulation) with a second polyimide alignment layer  39  applied over a third transparent substrate (typically an electrode panel)  46 . LCD medium  42  contains spacers, such as a plurality of glass spheres,  40  that separate first polyimide alignment layer  38  from second polyimide layer  39  on electrode panel  46  thereby forming the active region  43  of LCD. An epoxy seal  44  is applied to the perimeter of the electrode panel  46  before it is bonded to the second active surface  22  of signal plate  18 . As shown in FIG. 2, electrode panel  46  comprises an active electrode surface  48  containing an ITO coating layer  52  and an outer passive electrode surface  50  opposite active electrode surface  48 . Active electrode surface  48  generally faces LCD medium  42 .  
         [0025]    Referring to FIGS. 2, 3,  4  and  5 , in constructing LCD element  10  of the invention, deck plate or first transparent substrate  12  is provided with a first surface  14  and an opposed second surface  16 . Spacers  28  are bonded along peripheral edges  29 ,  31  of first surface  14  of deck plate  12  with a suitable adhesive, such as an epoxy. We prefer using an optical grade adhesive material  34  such as the same epoxy used to bond deck plate  12  and signal plate  18 . Alternatively, the spacers  28  could be integrally formed into the deck plate  12  by etching and machining the deck plate  12 . As can be appreciated in FIG. 2, signal plate  18  containing vias  30  filled with an optical grade adhesive material  34  provides a boundary wall for the liquid crystal when it is injected into the active region  43  of the LCD element  10 . Moreover, second surface  16  of deck plate  12  is coated with a protective ultra-violet transparent protective layer  24  of a predetermined thickness to prevent light penetration through deck plate  12  and into gap  11 . Those skilled in the art will appreciate that deck plate  12 , of the present invention, is not contemplated in existing LCD elements.  
         [0026]    With reference to FIG. 3, we have experimentally determined that the preferred thickness of spacers  28  structurally associated with deck plate  12  is about 0.150 mm. This preferred thickness of spacers  28  corresponds to deck plate  12  having a thickness of about 0.500-mm and a signal plate  18  having vias  30  with an average diameter of about 0.300-mm. Therefore, our experience indicates that the spacer thickness is modified based on the average diameter of the vias  30 . The thickness of spacer  28  must be controlled to allow the adhesive material to flow into the vias  30 .  
         [0027]    Referring again to FIG. 3, formation of undesirable voids in adhesive material  34  filling vias  30  as well as insufficient filling of the vias  30  with optical grade adhesive material  34 , preferably EpoTek  310 ™, are strongly influenced by the diameter of the vias  30  and dimensions of spacers  28 . As examples, vias  30  having an average diameter of about 0.300 mm and the absence of spacers  28  affixed to deck plate  12  have both shown to produce voids in vias  30  and filling problems. The same result was observed if the spacers  28  had a thickness of less than about 0.075 mm. Referring to FIG. 2, gap  11  defined by the height of spacers  28  enables the vias in the signal plate  18  to be filled efficiently without introducing voids or air bubbles into the vias  30 . As indicated previously, experience indicates that the presence of air bubbles in the vias  30  causes the light to scatter in the operating LCD.  
         [0028]    According to FIG. 4, signal plate  18 , in greater details, has opposed first and second active surfaces  20 ,  22 . In stark contrast, prior art signal plates only have one active surface. In constructing the LCD element  10 , first active surface  20  of signal plate  18  is bonded with a suitable optical grade adhesive material  34 , such as an epoxy, acrylic or ester, to second surface  16  of deck plate  12 . It is important to the invention that signal plate  18  has formed therein a plurality of vias  30 . Vias  30  pass between the first active surface  20  and the second active surface  22  to facilitate electrical continuity between the first active surface  20  and the second active surface  22 . Also, vias  30  in the signal plate  18  allow a higher patterning density for the LCD, thereby decreasing the LCD size. Vias  30  are filled with the optical grade adhesive material  34 , as described more fully below, that prevents the formation of voids or air bubbles in the optical grade adhesive material  34 . As indicated above in the prior art, voids or air bubbles in the adhesive filling become a source of undesirable light scatter (see for instance prior art FIG. 1).  
         [0029]    Referring to FIGS. 2 and 4, skilled artisans will appreciate that vias  30  in signal plate or second substrate  18  may be formed in one of several ways. We prefer vias that have been drilled in the signal plate or second substrate  18  because the drill process is easier to use and results in smoother wall surfaces within the vias hole.  
         [0030]    Referring to FIGS. 2 and 5, vias  30  in signal plate  18  are filled when the LCD element  10  of the invention is assembled. As indicated above, deck plate  12  is assembled with spacers  28  that spatially separate the deck plate  12  from the signal plate  18 . The optical grade adhesive material  34  is dispensed along the perimeter of the deck plate  12  in an optimized pattern to minimize voiding between the two substrates (first transparent substrate or deck plate  12  and second transparent substrate or signal plate  18 ). Moreover, spacers  28  allow the optical grade adhesive material  34  to fill the vias  30  without voids. The process disclosed herein allows the manufactured LCD panels to meet the specification of a void free epoxy plug in the vias  30  and a void free deck plate  12  attachment to the signal plate  18 . Voids in the adhesive either between the signal plate  18  and deck plate  12  or in the vias  30  of the signal plate  18  cause light to scatter in the LCD application.  
         [0031]    Referring again to FIGS. 2 and 5, wicking of the optical grade adhesive material  34  beyond vias  30  and onto ITO pattern features is controllable by, among other ways, a novel and unobvious dispensing process. Also, predetermining surface tension effects of optical grade adhesive material  34 , selectively designing cavity  70  in assembly fixture  60 , and predetermining the height of spacers  28  also play important roles in preventing the optical grade adhesive materials  34  from wicking beyond vias  30  and onto the ITO coating layer  32 . By using the dispensing process of the invention, vias  30  are filled to a plug height (h) that ranges from no more than about 5 microns above active surface  22  of signal plate  18  to not less than 40 microns below active surface  22  of signal plate  18 .  
         [0032]    Referring to FIG. 6, if optical grade material in vias  30  exceed a plug height (h) greater than about 5 microns beyond second active surface  22 , the excess material level  34   a  which extends into the polyimide layer  38  and into the liquid crystal medium  42  will interfere with the application, preferably coating, of polyimide alignment layer  38  onto the second surface  22  of signal plate  18 . Moreover, the excess material level  34   a  may interfere with the formation of patterns (not shown) on polyimide layer  38 . Furthermore, excess material level  34   a  may cause an increased separation between second active surface  22  and an active surface  48  of electrode panel  46 . Therefore, the result of excessive material level  34   a  in vias  30  would be improper alignment of the liquid crystal medium  42 .  
         [0033]    Referring now to FIG. 7, if optical grade material in vias  30  exceed a plug height (h) less than about 40 microns below the second active surface  22 , the deficient material level  34   b  which falls below the polyimide layer  38  in vias  30  will also interfere with the application, preferably coating, of polyimide alignment layer  38  onto the second surface  22  of signal plate  18 . Therefore, the result of deficient material level  34   b  in vias  30  would also be improper alignment of the liquid crystal medium  42 .  
         [0034]    Those skilled in the art will appreciate that several known processes exist for filling vias  30  in a workpiece, for instance, an LCD element. Among the method currently used include screen printing and pressure rolling. However, these alternative methods are known to exert a force on the LCD element  10  forcing the optical grade adhesive material  34  through vias  30  and thereby contaminating second active surface  22  of signal plate  18 . Of course, an additional process step would then be required which would include an adhesive removal and cleaning process. Experience has taught that optical grade adhesive material  34  removal affects the optical quality of the optical grade adhesive material  34  as well as the adherence of the remaining optical grade adhesive material  34  to interior walls  33  of vias  30 . Moreover, dispense processes, like screenprinting, introduce air into the vias  30  as the optical grade adhesive material  34  is dispensed into the vias  30 .  
         [0035]    Referring again to FIG. 5, an important novel and unobvious process for filling vias  30  free of air pockets or voids is now described. Our preferred adhesive material dispense process requires several important steps in order to construct the LCD element  10  of the invention. Assemblage for adhesive material dispense process  68  containing assembly fixture  60  is used. Assembly fixture  60  has a cavity  70  alignable under the vias  30  drilled in the signal plate  18 . Cavity  70  keeps the dispensed optical grade adhesive material  34 , such as epoxy, from exiting the vias  30  after the optical grade adhesive material  34  has flowed into the vias  30 . If the cavity  70  was not present in the assembly fixture  60 , then capillary action would continue to pull the epoxy out of the vias  30  and contaminate the second active surface  22  of signal plate  18  with epoxy and create voids in the vias  30 .  
         [0036]    According to FIG. 5, at the outset, signal plate  18  is placed in the assembly fixture  60  and a positioning bracket  61  is slid into place. The positioning bracket  61  was designed to hold the deck plate  12  in place during the epoxy dispensing process. The positioning bracket  61  allows the deck plate  12  to be aligned properly prior to adhesive dispense. Moreover, the positioning bracket  61  was designed with a gap  72  so it would not slide on top of first active surface  20  of signal plate  18 . Furthermore, it is important that the design of positioning bracket  61  not interfere with the optical grade adhesive material  34  as it flows between the deck plate  12  and signal plate  18 .  
         [0037]    Referring again to FIG. 5, after the deck plate  12  is positioned on top of the signal plate  18 , a stabilizing member, preferably a glass block  62 , is placed on top of the deck plate  12 . The weight of glass block  62  keeps the deck plate  12  from moving either rotationally or translationally, during adhesive dispensing. A quartz block is preferably used, however the glass block  62  could also be fabricated from other materials such as aluminum. Since the deck plate  12  is mounted to signal plate  18  at the same time the optical grade adhesive material  34  in the vias  30  is cured, some sort of supporting weight on the deck plate  12  is required. Without the glass block  62 , there would be thickness variations in LCD elements produced in this process. If the deck plate  12  is allowed to float, i.e., is not supported by glass block  62  or its equivalent, the deck plate  12  would displace the excess optical grade adhesive material  34  from the vias  30  to the second active surface  22  of the signal plate  18 . The same would result if deck plate  12  is allowed to stabilize to the plug height ( h ) of spacers  28  during adhesive material curing. Displacement of the optical grade adhesive material  34  invariably contaminates the patterned ITO and causes defective pixels in the LCD.  
         [0038]    Again referring to FIG. 5, once the signal plate  18  and deck plate  12  are arranged in the assembly fixture  60 , the optical grade adhesive material  34  is dispensed with an automated dispensing unit  63 . The dispensing unit  63  contains a base plate  65  with a heating element  66 , preferably a hot plate, that preheats the assembly fixture  60 , the signal plate  18 , and the deck plate  12 . Preheating assists the flow of the optical grade adhesive material  34 . The optical grade adhesive material  34  is dispensed in a predetermined pattern, preferably a substantially “L” shaped pattern along two perimeter edges of deck plate  12 . This technique prevents the occurrence of voids or air bubbles in the adhesive layer  34  between the signal plate  18  and deck plate  12 , as previously described. A void in adhesive material  34  causes incoming light to scatter during the LCD application. More particularly, adhesive material  34  is dispensed along perimeter  64  of the deck plate  12 . Capillary action allows the adhesive material  34  to flow between the deck plate  12  and the signal plate  18 . By dispensing adhesive material  34  along the perimeter  64  of the deck plate  12 , capillary action fills the gap  11  between the deck plate  12  and signal plate  18 . The 0.15-mm spacer  28  between the deck plate  12  and the signal plate  18  enables the adhesive material  34  to flow into the vias  30  without trapping air in the vias  30  and creating voids. Since surface tension controls the flow depth of the adhesive material  34  in vias  30 , when the adhesive material exits the vias  30 , surface tension keeps it from flowing out of the vias  30  onto the patterned ITO.  
         [0039]    The invention has been described with reference to a preferred embodiment. However, it will be appreciated that variations and modifications can be effected by a person of ordinary skill in the art without departing from the scope of the invention. PARTS LIST:  
         [0040]    [0040] 1  liquid crystal display element of prior art  
         [0041]    [0041] 2  vias in prior art LCD display element  
         [0042]    [0042] 3  prior art transparent substrate  
         [0043]    [0043] 4  prior art active surface second side signal plate  
         [0044]    [0044] 5  prior art active surface first side signal plate  
         [0045]    [0045] 6  indium tin oxide (ITO) layer  
         [0046]    [0046] 7  prior art deck plate  
         [0047]    [0047] 8  void in adhesive material  
         [0048]    [0048] 9  adhesive material layer  
         [0049]    [0049] 10  liquid crystal display element of the invention  
         [0050]    [0050] 11  gap  
         [0051]    [0051] 12  first transparent substrate or deck plate  
         [0052]    [0052] 14  first surface of deck plate  12   
         [0053]    [0053] 16  second surface of deck plate  
         [0054]    [0054] 18  second transparent substrate or signal plate  
         [0055]    [0055] 20  first active surface of signal plate  18   
         [0056]    [0056] 22  second active surface of signal plate  18   
         [0057]    [0057] 24  UV transparent protective layer  
         [0058]    [0058] 28  spacers  
         [0059]    [0059] 30  peripheral edge  
         [0060]    [0060] 31  vias  
         [0061]    [0061] 32  peripheral edge  
         [0062]    [0062] 33  ITO coating layer  
         [0063]    [0063] 34  interior wall of vias  
         [0064]    [0064] 34   a  optical grade adhesive material  
         [0065]    [0065] 34   b  excessive material level  
         [0066]    [0066] 36  deficient material level  
         [0067]    [0067] 38  signal plate  
         [0068]    polyimide alignment layer  
         [0069]    [0069] 40  spacer beads  
         [0070]    [0070] 42  Liquid crystal medium  
         [0071]    [0071] 43  active region of LCD element  10   
         [0072]    [0072] 44  epoxy seal  
         [0073]    [0073] 46  third transparent substrate or electrode panel  
         [0074]    [0074] 48  active electrode surface of electrode panel  46   
         [0075]    [0075] 50  passive electrode surface of electrode panel  46   
         [0076]    [0076] 52  ITO coating layer on electrode panel  46   
         [0077]    [0077] 60  assembly fixture  
         [0078]    [0078] 61  positioning bracket  
         [0079]    [0079] 62  glass block  
         [0080]    [0080] 63  Automated dispensing unit  
         [0081]    [0081] 64  Adhesive dispensed along perimeter of deck plate  12   
         [0082]    [0082] 65  base plate  
         [0083]    [0083] 66  heating element  
         [0084]    [0084] 68  assemblage for adhesive material dispense process  
         [0085]    [0085] 70  cavity under signal plate  
         [0086]    [0086] 72  gap between positioning bracket and signal plate