Abstract:
An assembly for enhancing an image displayed on a liquid crystal display (LCD) is disclosed. The assembly comprises a housing configured to surround a backlight, an optical sheet, and an LCD. The optical sheet being located between the backlight and the LCD. The assembly further comprises a spring assembly for tensioning the optical sheet.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 62/212,662, filed Sep. 1, 2015, which is incorporated by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    Embodiments generally relate to backlighting assemblies with optical sheets. 
       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. 
         [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 provide a spring tensioning assembly for an optical sheet. In some embodiments the tensioning springs are provided as flat or leaf springs while in other embodiments the tensioning springs can be traditional extension springs or torsion springs. 
         [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 an exemplary embodiment of an assembly for back to back LCDs and showing the section line  1 - 1 . 
           [0009]      FIG. 2  is a perspective section view of the assembly taken from section line  1 - 1  and showing the location for detail A. 
           [0010]      FIG. 3  is a perspective section view of detail A. 
           [0011]      FIG. 4  is a top plan view of the embodiments shown above where the transparent protective plate and the LCD have been removed, and indicating the location for detail B. 
           [0012]      FIG. 5  is a top plan view of detail B. 
           [0013]      FIG. 6  is a top perspective view of detail B. 
           [0014]      FIGS. 7A-7D  provide top plan views for various embodiments for the placement of tensioner springs and securing posts on various perimeter edges of the optical sheet. 
           [0015]      FIG. 8  is a side perspective sectional view of another exemplary embodiment of the present invention showing Detail C and Detail D. 
           [0016]      FIG. 9  is a detailed side perspective sectional view of Detail C of  FIG. 8 , also showing Detail E. 
           [0017]      FIG. 10  is a detailed front perspective sectional view of Detail E of  FIG. 9 . 
           [0018]      FIG. 11  is a top perspective sectional view of Detail E of  FIG. 9 . 
           [0019]      FIG. 12  is a detailed top perspective sectional view of Detail D of  FIG. 8 , shown with the plate  300  removed. 
           [0020]      FIG. 13  is a detailed top perspective sectional view of Detail D of  FIG. 8 , shown with the plate  300  and the LCD  100  removed. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    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. 
         [0022]    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. 
         [0023]    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. 
         [0024]    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. 
         [0025]      FIG. 1  is a perspective view of a car top assembly  401  for back to back LCDs and showing the section line  1 - 1 . A housing  400  preferably contains and protects the components and has mounting plates  410  as well as an ambient air inlet  200  and ambient 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. 
         [0026]    Fans  375  may be positioned within the housing  400  to force the ambient 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  1 - 1  is shown cutting vertically through the assembly  401 . 
         [0027]      FIG. 2  is a perspective section view of the car top assembly taken from section line  1 - 1  and showing the location for detail A. 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 in a preferred embodiment. Both the first and second sides preferably contain an embodiment of the LCD assembly  199 . The assembly preferably contains two paths for cooling air. The first path (open loop) is ambient 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. The open loop is forced by the fans  375  described above. 
         [0028]    The second path (closed loop) may be 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 . 
         [0029]      FIG. 3  is a perspective section view of detail A. The 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 may accept the closed loop circulating gas. The backlight  160  is preferably positioned behind the optical sheet  130  and is preferably in conductive thermal communication with a front thermal plate  170 . An optional 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. 
         [0030]    A series of channels  198  may be 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 . 
         [0031]      FIG. 4  is a top plan view of the embodiments shown above where the transparent protective plate  300  and the LCD  100  have been removed, and indicating the location for detail B. The optical sheet  130  is generally a thin plastic sheet which has a size and shape that is similar to that of the LCD  100  and may be configured to diffuse or otherwise scatter light. As further illustrated in  FIG. 9 , the optical sheet  130  may comprise one or more of the following, a diffuser  512 , a light diffusion film (LDF)  514 , a dual brightness enhancement film (DBEF)  518 , a brightness enhancement film (BEF)  516 , a polarizer, and an anti-reflective film. These are merely exemplary, those having an ordinary level of skill in the arts will recognize that any type of optical sheet, stack, and/or film may be used with the present invention in any combination, the components of which may be used to diffuse, scatter, collimate, polarize, enhance, or otherwise alter the light passing therethrough. The optical sheet  130  preferably has four perimeter edges, where one or more of the edges may be secured to the  150 , preferably by passing a post  450  from the backlight wall  150  through an aperture  132  placed near the perimeter edge of the optical sheet  130 . Any number of posts  450  and corresponding apertures  132  may be used. At least one perimeter edge of the optical sheet  130  preferably contains one or more apertures  131  for tensioning the optical sheet  130 . 
         [0032]      FIG. 5  is a top plan view of detail B. A tensioner spring  145  preferably contains a hook  146  or similar means for attaching the tensioner spring  145  to the aperture  131  in the optical sheet  130 . In some embodiments, the hook  146  may be inserted directly into the aperture  131 . In other embodiments, as shown here, an intermediary element  141  passes through the aperture  131  and connects with the tensioner spring  145 . Here, the intermediary element  141  comprises a strip of flexible material (preferably plastic or sheet metal) which passes through the aperture  131  and is folded over upon itself. An aperture  142  is preferably placed on the intermediary element  141  to provide a location for the hook  146  of the tensioner spring  145 . In this embodiment, the aperture  142  passes through the intermediary element  141  twice since the intermediary element  141  is folded over upon itself. Preferably, the apertures  131  in the optical sheet  130  are slots while the apertures  142  in the intermediary element  141  are round holes. However, if the hook  146  of the tensioner spring  145  were to connect directly with the optical sheet  130 , then the apertures  131  in the optical sheet  130  would preferably be rounded holes. 
         [0033]    Although shown herein with a leaf or flat spring design, the tensioner spring  145  could be any number of biasing elements including but not limited to traditional extension springs as well as torsion springs. In the particular design shown, one or more posts  148  are used to create a first portion of the tensioner spring  145  that is substantially parallel to the adjacent edge of the optical sheet  130 . While posts  148  are used here, this could also be any surface which is substantially parallel to the adjacent edge of the optical sheet  130  or any element to keep the first portion of the tensioner spring  145  substantially parallel to the adjacent edge of the optical sheet  130 . Thus, in this embodiment the tensioner spring  145  contains a first portion which is substantially parallel to the adjacent edge of the optical sheet  130  and a second portion which angles towards the optical sheet  130  and contains an end having the hook  146  (or other means for attaching to the apertures  131  or  142 ). 
         [0034]      FIG. 6  is a top perspective view of detail B. The end of the tensioner spring  145  which is opposite the hook  146  preferably contains a hollow portion  145  which can accept a locating post  149  (which is shown here as a threaded fastener, but this is not required as any object which fits within the hollow portion  145  will perform adequately). 
         [0035]      FIGS. 7A-7D  provide top plan views for various embodiments for the placement of tensioner springs  145  and securing posts  450  on various perimeter edges of the optical sheet  130 . The embodiment of  FIG. 7A  uses securing posts  450  along each edge except for one edge which contains the tensioner springs  145 . The embodiment of  FIG. 7B  provides tensioner springs  145  along two opposing edges of the optical sheet  130  while the remaining edges contain securing posts  450 . The embodiment of  FIG. 7C  shows tensioner springs  145  along two adjacent perimeter edges of the optical sheet  130  while the remaining edges (the opposite set of adjacent perimeter edges) contain securing posts  450 . The embodiment of  FIG. 7D  provides tensioner springs  145  along each perimeter edge of the optical sheet  130 . It should be noted that although shown in a rectangular-portrait orientation, this is not required by any of the claims as all teachings could be applied to rectangular-landscape orientation or displays which are square. These embodiments are merely exemplary, any location of tensioner springs  145  and securing posts  450  is contemplated. 
         [0036]      FIG. 8  is a side perspective sectional view of another exemplary electronic display assembly  501  in accordance with the present invention. Similar to other embodiments described herein, the assembly may comprise the housing  400 , the plate  300 , and an open and closed loop of gas, which may be propelled by one or more of the fans  375  positioned at various locations within the housing  400 . In exemplary embodiments of the present invention, the open loop may be comprised of ambient air and may travel through a series of channels  198  and a heat exchanger  393 . A closed loop of circulating gas may travel between the LCD  100  and the plate  300 , vertically along the upper and lower edges of the assembly  501  and across the bottom of the housing  400 . The circulating gas may travel vertically by way of one or more pass through apertures  510 . 
         [0037]      FIG. 9  is a detailed side perspective sectional view of Detail C. The optical sheet  130  may comprise one or more of the following, the diffuser  512 , the light diffusion film (LDF)  514 , the dual brightness enhancement film (DBEF)  518 , the brightness enhancement film (BEF)  516 , the polarizer, and the anti-reflective film. These are merely exemplary, those having an ordinary level of skill in the arts will recognize that any type of optical sheet, stack, and/or film may be used with the present invention in any combination, the components of which may be used to diffuse, scatter, collimate, polarize, enhance, or otherwise alter the light passing therethrough 
         [0038]      FIG. 10  is a detailed section view of Detail E, shown from a front view. The backlight wall  150  may be curved such that it contacts the backlight  160  and the optical sheet  130  in an “S” type shape. In exemplary embodiments of the present invention, the backlight wall  150  may contact the diffuser  512 , though in other exemplary embodiments the backlight wall  150  may contact other elements of the optical sheet  130 . The spring assembly  145  may reside in the space created by the curved shape of the backlight wall  150 , though any location is contemplated. The intermediary element  141  may be attached to the optical sheet  130 . Preferably, the intermediary element  141  may wrap around one or more layers of the optical sheet  130 . 
         [0039]      FIG. 11  is a detailed sectional view of Detail E from a rear perspective. The intermediary element  141  may rest beneath the LCD  100 . Therefore, it is desirable that the intermediary element  141  be comprised of a material of high stiffness (so as to transfer the tensioning force to the optical sheet  130 ), tear-resistance (so the hook  146  does not enlarge, tear, or otherwise compromise the aperture  142 ), thin (so at to not add thickness to the assembly  501 ), and smooth (such that it does not scratch the LCD  100 ). In exemplary embodiments of the present invention, the intermediary element  141  may be comprised of a polymer, a reinforced tape, or a woven material, though any material is contemplated. 
         [0040]      FIG. 12  is a detailed top perspective sectional view of Detail D of  FIG. 8 , shown with the plate  300  removed. The tensioner spring  145  may be biased such that it would normally extend substantially parallel to the edge of the backlight wall  150 . The first portion of the tensioner spring  145  be retrained by the posts  148  and a second portion of the tensioner spring  145  may be manipulated upward and made to engage the intermediary element  141  such that the tensioner spring  145  creates a downward force against the intermediary element  141  and thus the optical sheet  130 . 
         [0041]      FIG. 13  is a detailed top perspective sectional view of Detail D of  FIG. 8 , shown with the plate  300  and the LCD  100  removed to expose the optical sheet  130 . As illustrated, the optical sheet  130  may be comprised of multiple layers such as the diffuser  512 , the light diffusion film (LDF)  514 , the dual brightness enhancement film (DBEF)  518 , and the brightness enhancement film (BEF)  516 . The intermediary element  141  may wrap around and engage one or more of these layers, thus providing a tensioning force against these layers. 
         [0042]    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.