Abstract:
Exemplary embodiments disclosed herein provide a rigid LCD assembly including a LCD having a perimeter, a first layer of tape around the perimeter of the LCD, and a diffusing plate attached to the later of tape so as to create a cavity defined by the space between the LCD, tape, and diffusing plate. One or more optical films may be inserted into the cavity, and while constricted in directions perpendicular to the films, the films may be free to move slightly in the directions parallel to the films. A U-shaped backlight wall may attach to the diffusing plate and would contain a backlight. An optional thermal plate can be attached to the backlight wall, which can be used with a second thermal plate to define a channel for accepting cooling air.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application No. 61/785,285, filed on Mar. 14, 2013, which is herein incorporated by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    Embodiments generally relate to liquid crystal display assemblies. 
       BACKGROUND OF THE ART 
       [0003]    Liquid crystal displays (LCDs) are now being used in many environments which are not protected from direct sunlight, shock, or high/low ambient temperatures. Specifically, it is now desirable to place LCDs on a moving vehicle, typically for advertising or informational purposes. While they can be placed anywhere on the vehicle, it is sometimes preferred to place the LCDs atop the vehicle, attached to the roof. Of course, traditional LCDs are not capable of withstanding the impacts of sunlight, weather, high/low ambient temperatures, as well as the shock that would be transferred to the LCD when the vehicle hits potholes, curbs, speed bumps, and sometimes other vehicles. 
         [0004]    The various layers used to construct an LCD are typically very thin, as the thinner LCD assemblies have been more popular in the marketplace and are typically more appealing to the consumer. However, thin components have been difficult to form into a resulting assembly that is durable enough to withstand this particular application and all of the competing environmental factors, while still producing a very bright, high quality image that does not degrade over time. 
       SUMMARY OF THE EXEMPLARY EMBODIMENTS 
       [0005]    Exemplary embodiments disclosed herein provide a rigid LCD assembly including a LCD having a perimeter, a first layer of tape around the perimeter of the LCD, and a diffusing plate attached to the later of tape so as to create a cavity defined by the space between the LCD, tape, and diffusing plate. One or more optical films may be inserted into the cavity, and while constricted in directions perpendicular to the films, the films may be free to move slightly in the directions parallel to the films. A U-shaped backlight wall may attach to the diffusing plate and would contain a backlight. An optional thermal plate can be attached to the backlight wall, which can be used with a second thermal plate to define a channel for accepting cooling air. 
         [0006]    The foregoing and other features and advantages of the exemplary embodiments 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 
         [0007]    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: 
           [0008]      FIG. 1  is a perspective view of a car top assembly for back to back LCDs and showing the section line  2 - 2 . 
           [0009]      FIG. 2  is a perspective section view of the car top assembly taken from section line  2 - 2  and showing the location for detail  3 . 
           [0010]      FIG. 3  is a perspective section view of detail  3 . 
           [0011]      FIG. 4  is a perspective view of an exemplary embodiment for the rigid LCD assembly and showing the section line  5 - 5 . 
           [0012]      FIG. 5  is a perspective section view taken from section line  5 - 5  and showing detail  6 . 
           [0013]      FIG. 6  is a perspective section view of detail  6 . 
           [0014]      FIG. 7  is a perspective illustration of the car top LCD assembly of  FIG. 1  shown mounted atop an automobile. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    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. 
         [0016]    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. 
         [0017]    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. 
         [0018]    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. 
         [0019]      FIG. 1  is a perspective view of a car top assembly  401  for back to back LCDs and showing the section line  2 - 2 . A housing  400  contains and protects the components and has mounting plates  410  as well as an external air inlet  200  and external air outlet  210 . The housing  400  is preferably metal but this is not required. A transparent protective plate  300  is used to protect the internal LCD. In an exemplary embodiment the plate  300  would be glass and would contain at least one anti-reflective layer or coating. In some embodiments the plate  300  may be a single pane of tempered glass while in other embodiments the plate  300  may be two pieces of anti-reflective glass laminated together with optical adhesive. 
         [0020]    Fans  375  may be positioned within the housing  400  to force the external air through the inlet  200  and outlet  210 . Fans  375  could be positioned anywhere within the housing  400 , but are preferably near either the inlet  200  or outlet  210 . Fans  375  may be placed near both the inlet  200  and outlet  210  or only near one of the two. Section line  2 - 2  is shown cutting vertically through the assembly  401 . 
         [0021]      FIG. 2  is a perspective section view of the car top assembly taken from section line  2 - 2  and showing the location for detail  3 . In an exemplary embodiment, the assembly is substantially symmetrical about a vertical center plane, so the assembly will be described mostly with reference to a first side, as the second side is substantially the same. Both the first and second sides preferably contain an embodiment of the rigid LCD assembly  199 . The assembly preferably contains two paths for cooling air. The first path (open loop) is external air which is drawn through the inlet  200  and preferably forced through a first heat exchanger  392 , second heat exchanger  391 , behind a first backlight  160 , and behind a second backlight (for the opposing LCD). The open loop is forced by the fans  375  described above. 
         [0022]    The second path (closed loop) is used to force circulating air through a first heat exchanger  392 , second heat exchanger  391 , between the protective plate  300  and a first LCD, and between a second protective plate and a second LCD. The circulating gas is preferably forced through the closed loop path by fan  380 , which could be placed anywhere in the path of the closed loop, but here is shown above the first and second heat exchangers  392  and  391 . The second path (closed loop) can be thought of as a single figure-8 type flow or a combination of loops. The first loop can be described as beginning at the fan  380 , travelling through the heat exchanger  392 , continuing between the rigid LCD assembly  199  and the transparent protective plate  300 , and finally returning to the fan  380 . The second loop would also begin at the fan  380 , but would instead travel through the heat exchanger  391 , continuing between the opposing LCD assembly and the opposing transparent protective plate, and finally returning to the fan  380 . 
         [0023]    Preferably, the circulating air traveling through the closed loop is not permitted to mix with the external air travelling through the open loop. This prevents dust, water vapor, pollen, and other contaminates from entering sensitive portions of the display, specifically the gap  505  between the two heat exchangers as well as the gap between the rigid LCD assembly  199  and the transparent protective plate  300 . The gap  505  is preferably used to house the electronics for powering and driving the rigid LCD assemblies. 
         [0024]      FIG. 3  is a perspective section view of detail  3 . The rigid LCD assembly  199  preferably contains an LCD  100  as the outermost layer. A gap is preferably defined between the LCD  100  and the plate  300 , which accepts the closed loop circulating gas. The backlight  160  is positioned behind the diffuser  130  and is preferably in conductive thermal communication with a front thermal plate  170 . A corrugated layer  180  is preferably sandwiched between the front thermal plate  170  and a rear thermal plate  190 . Preferably, the corrugated layer  180  is in conductive thermal communication with the front thermal plate  170  and rear thermal plate  190 . In an exemplary embodiment, the front thermal plate  170 , rear thermal plate  190 , and corrugated layer  180  are all comprised of metal and even more preferably of aluminum or stainless steel. Also in an exemplary embodiment, the corrugated layer  180  would contact the front thermal plate  170  and rear thermal plate  190  in an alternating fashion. 
         [0025]    A series of channels  198  are preferably defined by the combination of the front thermal plate  170 , rear thermal plate  190 , and corrugated layer  180 . The channels  198  guide the open loop air and allow heat to be removed from the backlight  160  by transferring to the heat to the front thermal plate  170 , rear thermal plate  190 , and corrugated layer  180 . In some embodiments, the corrugate layer  180  may not be used, but the open loop air is simply forced between the front thermal plate  170  and rear thermal plate  190 . 
         [0026]      FIG. 4  is a perspective view of an exemplary embodiment for the rigid LCD assembly  199  and showing the section line  5 - 5 . As shown, an exemplary embodiment for the rigid LCD assembly  199  would contain each layer found between the LCD  100  and the rear thermal plate  190 .  FIG. 5  is a perspective section view taken from section line  5 - 5  and showing detail  6 . 
         [0027]      FIG. 6  is a perspective section view of detail  6 . A layer of adhesive  110  is preferably used to bond the LCD  100  to a diffuser plate  130 , sandwiching one or more optical films  120  in between the LCD  100  and the diffuser plate  130 . It is preferable to provide the adhesive  110  in a thickness that is approximately equal to the thickness of the optical films  120  as this would prevent the films from shifting, bunching, or buckling due to thermal or shock issues. It may be preferable to constrain the optical films in a cavity (defined between the LCD  100 , diffuser plate  130 , and adhesive  110 ) that is approximately the same thickness as the optical films  120  but has a length and width which is slightly larger than the films, to allow for thermal expansion/contraction without buckling. In other words, it may be preferable to allow the optical films  120  to float within the directions parallel to the films themselves, while constraining the films to prevent movement within directions perpendicular to the optical films  120 . The adhesive  110  is generally placed around the perimeter of the diffuser plate  130 . 
         [0028]    While not required, it is preferable that the diffuser plate  130  is a glass plate, which helps to provide rigidity to the assembly. In an exemplary embodiment, the diffuser plate  130  is a glass plate with a coating or treatment on the front surface which causes the diffusion of the light. In some embodiments the front surface of the glass may have a thin white flashed layer. In a preferred embodiment, the diffuser plate  130  would comprise Opalika® filterglass from Schott North America. The data sheet for Opalika® filterglass can be found at www.us.schott.com/architecture and is herein incorporated by reference in its entirety. It should be noted that while a plate is preferred for the diffuser  130 , a traditional diffuser film or plastic plate could also be used in some embodiments. 
         [0029]    Another layer of adhesive  140  is preferably used to bond the diffuser plate  130  to the backlight cavity walls  150 , which in an exemplary embodiment have a U-shaped cross-section and would be formed sheet metal. The backlight cavity walls  150  are preferably attached to the front thermal plate  170 , which is preferably in contact with the backlight  160 . The backlight  160  is preferably a metal printed circuit board having a plurality of LEDs. The rear thermal plate  190  may be attached to the front thermal plate  170  so as to interpose the corrugated layer  180  in between. The layer of adhesive  140  is preferably placed around the perimeter of the diffuser  130 . 
         [0030]    In a preferred embodiment, the backlight cavity walls  150  would have a U-shaped cross-section defined by a top ledge  341  with a top surface, bottom ledge  343  with a bottom surface, and a sidewall  342  connecting the top ledge  341  with the bottom ledge  343 . In a preferable arrangement, the top ledge  341  and bottom ledge  343  would be substantially parallel and the sidewall  342  would be substantially perpendicular to the top ledge  341  and bottom ledge  343 . Preferably, the top surface of the top ledge  341  would attach to the adhesive  140  while the bottom surface of the bottom ledge  343  would attach to the front thermal plate  170 . 
         [0031]    The adhesive layers  140  and  110  could be any number of adhesives, but are preferably very high bond (VHB) tape. In this way, the thickness of the VHB tape could be selected to be similar to the thickness of the optical films  120 . Although not required, the adhesive layers  140  and  110  would preferably run all around the perimeter of the assembly  199  so as to completely seal each of the layers and prevent dust and contaminates to enter the assembly and disrupt any resulting images or damage the components. 
         [0032]      FIG. 7  is a perspective illustration of the car top LCD assembly  401  of  FIG. 1  shown mounted atop an automobile  500 . 
         [0033]    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.