Abstract:
The exemplary embodiments herein provide a transparent liquid crystal display (LCD) assembly having a glass panel with an LCD panel placed in front of the glass panel. A light guide may be positioned between the LCD panel and the glass panel and the light guide may have an edge. A substrate containing a plurality of LEDs is preferably positioned adjacent to the edge of the light guide and a thermal plate is preferably attached to both the substrate and the glass panel. The thermal plate may contain two portions which are substantially perpendicular to each other, where one of the portions is substantially parallel to the glass panel. In some embodiments, the LCD may be sandwiched in between a pair of glass panels, held opposite one another by a spacer.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application No. 62/012,785 filed on Jun. 16, 2014 which is herein incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     Embodiments generally relate to cooling systems for transparent liquid crystal displays (LCD) and traditional LCDs. 
     BACKGROUND OF THE ART 
     Display cases are used in a number of different retail establishments for illustrating the products that are available for sale. In some instances these display cases may be coolers or freezers which are placed in grocery stores, convenience stores, gas stations, restaurants, or other retail establishments. In other instances these display cases may be non-refrigerated transparent containers used in a jewelry or watch store, bakery, deli, antique shop, sporting goods store, electronics store, or other retail establishments. While the design and appearance of the product itself does provide some point-of-sale (POS) advertising, it has been found that additional advertising at the POS can increase the awareness of a product and in turn create additional sales. 
     Most retail establishments already contain some POS advertising, and depending on the type of establishment the proprietor may want to limit the amount of ‘clutter’ in the retail area—resulting in a very limited space for additional POS advertising. It has now become desirable to utilize the transparent glass that is typically placed in display cases with additional POS advertising. Most notably, it has been considered that transparent LCDs may be positioned along with the transparent glass and could display additional advertising materials while still allowing a patron to view the products inside the display case. 
     SUMMARY OF THE EXEMPLARY EMBODIMENTS 
     An exemplary embodiment provides a cooling system for a transparent LCD assembly. LEDs are preferably arranged along the top and bottom edges of a two way light guide which permits the light to exit both the front and rear surface of the light guide. The top LEDs are preferably placed in thermal communication with a top thermal plate which is placed in conductive thermal communication with the rear glass. Similarly, the bottom LEDs are preferably placed in thermal communication with a bottom thermal plate which is also placed in conductive thermal communication with the rear glass. The top and bottom thermal plates permit the heat to spread out and transfer to the rear glass where it can be removed by forced or natural convection. 
     The foregoing and other features and advantages of the present invention will be apparent from the following more detailed description of the particular embodiments, as illustrated in the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A better understanding of an exemplary embodiment will be obtained from a reading of the following detailed description and the accompanying drawings wherein identical reference characters refer to identical parts and in which: 
         FIG. 1  is a perspective view of a display case having an exemplary sealed transparent LCD assembly. 
         FIG. 2  is a perspective view of the display case of  FIG. 1  where the door has been opened. 
         FIG. 3  is a perspective view of the sealed transparent LCD assembly of  FIGS. 1-2 . 
         FIG. 4  is a front planar view of the sealed transparent LCD assembly, showing the section lines A-A and B-B. 
         FIG. 5  is a section view taken along the section line A-A shown in  FIG. 4  and indicating Detail A and Detail B. 
         FIG. 6  is a section view taken along the section line B-B shown in  FIG. 4  and indicating Detail C. 
         FIG. 7  is a detailed section view of Detail A shown in  FIG. 5 . 
         FIG. 8  is a detailed section view of Detail B shown in  FIG. 5 . 
         FIG. 9  is a detailed section view of Detail C shown in  FIG. 6 . 
         FIG. 10  is a perspective view of a partially assembled exemplary embodiment of a sealed transparent LCD assembly. 
         FIG. 11  is a simplified partial view of an exemplary embodiment of the lower thermal plate. 
         FIG. 12  is a simplified partial view of an exemplary embodiment of the upper thermal plate. 
     
    
    
     DETAILED DESCRIPTION 
     The invention is described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     Embodiments of the invention are described herein with reference to illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of the invention. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments of the invention should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
       FIG. 1  is a perspective view of a display case having an exemplary sealed transparent LCD assembly  200 . Generally, the display case includes a housing  105 , to which a door frame assembly  100  is fastened. In this embodiment, a cavity  110  is provided below the door frame assembly  100  where various electronic devices  111  for operating the transparent LCD assembly  200  can be located. The electrical devices  111  may include any or all of the following: timing and control board (TCON), video player, hard drive/storage, microprocessor/CPU, wireless transmitter/receiver, cellular data transmitter/receiver, and internet connectivity. At least some of the electrical devices  111  are in electrical communication with the transparent LCD  230 . 
       FIG. 2  is a perspective view of the display case of  FIG. 1  where the door has been opened. 
       FIG. 3  is a perspective view of the sealed transparent LCD assembly  200  of  FIGS. 1-2 . Generally speaking, the assembly includes a spacer  300  which is sandwiched between a front glass  225  and rear glass  205 . These components are preferably sealed together with an inert gas filling the sealed enclosure. Although not required for every embodiment, argon gas has been found to be preferred in the exemplary embodiments. For sealing these components together, it is preferable to use a hot melt polyurethane. Preferably, the spacer  300  is the Super Spacer® Standard from Quanex in Cambridge, Ohio. www.quanex.com. In an exemplary embodiment, the spacer  300  would be a flexible foam that contains a desiccant and has a pressure sensitive acrylic adhesive on the front and back edges of the spacer which would be used to bond with the front and rear glass. 
       FIG. 4  is a front planar view of the sealed transparent LCD assembly, showing the section lines A-A and B-B.  FIG. 5  is a section view taken along the section line A-A shown in  FIG. 4  and indicating Detail A and Detail B.  FIG. 6  is a section view taken along the section line B-B shown in  FIG. 4  and indicating Detail C. 
       FIG. 7  is a detailed section view of Detail A shown in  FIG. 5 . A top thermal plate  216  is preferably bonded to the rear glass  205 . In an exemplary embodiment, the top thermal plate  216  is preferably bonded to the rear glass  205  through adhesive transfer tape. An exemplary adhesive transfer tape for this purpose would be 468 MP, available commercially from 3M™ of St. Paul, Minn. www.3M.com/converter. A printed circuit board (PCB)  246  containing a plurality of LEDs  276  is preferably attached to the top thermal plate  216  and is preferably in conductive thermal communication with the top thermal plate  216  as well. In this way, heat that is generated by the LEDs  276  can be transmitted to the PCB  246 , top thermal plate  216 , and eventually transferring to the rear glass  205  where the heat can dissipate through natural or forced convection. 
     The LEDs  276  are placed adjacent to the edge of a light guide  220  which is sandwiched between a rear bracket  211  and a front bracket  236 . Generally speaking, the light guide  220  is only constrained from movement towards the front or back of the assembly, but is not constrained from movement towards the top or sides of the assembly. In other words, the light guide  220  is secured such that it is capable of thermal expansion/contraction in the X-Y direction (horizontal and vertical when observing the LCD), but is fixed in the Z direction (into/out of the assembly when observing the LCD). It could also be said that the light guide  220  is constrained so that it cannot move towards the front or rear glass but otherwise is permitted to float between the rear bracket  211  and front bracket  236 . In an exemplary embodiment, the light guide  220  would be the Acrylite® LED Endlighten product available from Evonik Industries. www.acrylite-shop.com. 
     Preferably, the light guide  220  would contain microscopic diffuse particulate that is homogeneously scattered throughout the sheet. Also preferably, the light emitted from the LEDs  276  and  275  is permitted to exit both the front and rear surfaces of the light guide  220  (in this way, the light guide  220  could be referred to as a ‘two way light guide’). In an exemplary embodiment, the light is permitted to exit the rear of the light guide  220  so as to illuminate the products within the display case. Thus, it is preferable that the amount of light permitted to exit the rear surface of the light guide  220  is at least 20% of the amount of light permitted to exit the front surface of the light guide  220 . 
     The transparent LCD  230  is preferably attached to a front surface of the front bracket  236  through a layer of adhesive  241  which would preferably be applied around the perimeter of the LCD  230 . In an exemplary embodiment, the adhesive  241  would be VHB tape and preferably 5052 VHB Tape available commercially from 3M™ of St. Paul, Minn. www.3M.com. 
       FIG. 8  is a detailed section view of Detail B shown in  FIG. 5 . A bottom thermal plate  215  is preferably bonded to the rear glass  205 . In an exemplary embodiment, the bottom thermal plate  215  is preferably bonded to the rear glass  205  through adhesive transfer tape. An exemplary adhesive transfer tape for this purpose would be 468 MP, available commercially from 3M™ of St. Paul, Minn. www.3M.com/converter. A printed circuit board (PCB)  245  containing a plurality of LEDs  275  is preferably attached to the bottom thermal plate  215  and is preferably in conductive thermal communication with the bottom thermal plate  215  as well. In this way, heat that is generated by the LEDs  275  can be transmitted to the PCB  245 , bottom thermal plate  215 , and eventually transferring to the rear glass  205  where the heat can dissipate through natural or forced convection. 
     The LEDs  275  are placed adjacent to the edge of a light guide  220  which is sandwiched between a rear bracket  211  and a front bracket  236 . As discussed at length above, the light guide  220  is preferably only constrained from movement towards the front or back of the assembly, but is not contained from movement towards the top or sides of the assembly. 
       FIG. 9  is a detailed section view of Detail C shown in  FIG. 6 . 
       FIG. 10  is a perspective view of a partially assembled exemplary embodiment of a sealed transparent LCD assembly. This view shows the rear glass  205  with the spacer  300  attached around the perimeter of the glass  205 . Also shown is the rear bracket  211  which may be attached to the rear glass  205  as well. 
       FIG. 11  is a simplified partial view of an exemplary embodiment of the lower thermal plate  215 . In a preferred embodiment, the lower thermal plate  215  would extend horizontally as far as possible, preferably to the same horizontal width as the LCD  230  and may extend 4-14 inches in vertical width, depending on the application. In this embodiment, electrical devices  400  are mounted to the thermal plate  215  and can include, but are not limited to: power modules, wireless or satellite receiver/transmitter, video player, hard drive, microprocessor, and printed circuit boards. Although shown attached to the lower thermal plate  215 , electrical devices  400  could also be mounted to the upper thermal plate  216 . Preferably, the electrical devices  400  are also in conductive thermal communication with the thermal plate  215 / 216  so that heat which is generated by the electrical devices  400  can be transferred to the thermal plate  215 / 216  and eventually to the rear glass  205 , where it can be removed by natural or forced convection. 
       FIG. 12  is a simplified partial view of an exemplary embodiment of the upper thermal plate. Again, in a preferred embodiment, the upper thermal plate  216  would extend horizontally as far as possible, preferably to the same horizontal width as the LCD  230 . The upper thermal plate  216  may also extend 4-14 inches in vertical width, depending on the application. While not required, it is also preferred that the lower thermal plate  215  and the upper thermal plate  216  are within 15% of the same surface area. In other words, it is preferred that the plates  215 / 216  are substantially the same surface area. This is not required, however, as some embodiments may require a larger surface area for the plate which would contain the electrical devices  400 , or a larger surface area for the top plate  216  as compared to the bottom plate  215 . It is preferred that the thermal plates are both metallic, and most preferably aluminum, but they can be any material that has good thermal conductivity. 
     The embodiments of the cooling system described herein can be used with any number of display case designs, either temperature controlled or not, and with doors that open, or glass that remains stationary. Although shown here with a transparent LCD, the cooling system could be used with a traditional backlit LCD as well. 
     Having shown and described a preferred embodiment of the invention, those skilled in the art will realize that many variations and modifications may be made to affect the described invention and still be within the scope of the claimed invention. Additionally, many of the elements indicated above may be altered or replaced by different elements which will provide the same result and fall within the spirit of the claimed invention. It is the intention, therefore, to limit the invention only as indicated by the scope of the claims.