Abstract:
Tiled flat-panel displays have increased mechanical stability due to the addition of stiffening straps affixed across seams between individual display modules. The stiffening straps may increase mechanical strength of the display by redistributing stress placed on the display from the front of the display to the straps.

Description:
BACKGROUND  
         [0001]    This invention relates generally to tiled, flat-panel displays.  
           [0002]    Flat-panel displays are widespread in their use. For example, watches, clocks, telephones, and laptop computers may all incorporate flat-panel displays. Because of the relatively small size of the flat panel displays used in the above examples, they are usually monolithic.  
           [0003]    A monolithic display may be limited in size due to a variety of factors. For example, increasing the size of an active matrix liquid crystal display by one square inch may require millions of dollars to be invested in capital equipment and may lead to an increase in component failure or malfunction. Moreover, in general, increasing the size of monolithic flat-panel displays may also increase the number of defects per unit of area so that the yield of functional displays is low. That means increased cost to the consumer to compensate for the loss of functional displays during the manufacturing process. Thus, very large flat-panel displays may not be cost effective.  
           [0004]    One way to circumvent the size limitations placed on monolithic flat-panel displays is to use an array of smaller display modules. The smaller display modules may be “tiled” to create a large display that appears monolithic to the viewer.  
           [0005]    A variety of devices may utilize a large, tiled, flat-panel display. For example, large screen televisions, public information displays, displays in public trading rooms, displays at sporting arenas, and electronic signs may all incorporate a large array, tiled, flat-panel display.  
           [0006]    Sandwiching an array of display modules between two glass plates may lend mechanical stability to tiled, flat-panel displays. Increasing the thickness of the glass plates may further increase the mechanical stability of the tiled displays.  
           [0007]    Placing tiled, flat-paneled displays in a “picture” or “window” frame may also lend mechanical stability to the displays. The frame may reduce a large display&#39;s tendency to twist and bend at the periphery. However, the frame may not prohibit bending and twisting at the front or back of the display, away from the periphery. For example, in an outdoor sporting arena, wind may cause a large display to bend or bow in or out at the center of the display.  
           [0008]    Mechanical stability that is obtained by using thick glass plates and robust frames may increase the weight and cost of large displays without significantly reducing their tendency to bend or to bow. Thus, the increase in the weight and cost of the large displays may outweigh the benefits of known mechanical strengthening techniques.  
           [0009]    Therefore, there is a need to improve the mechanical stability for tiled, flat-panel displays without significantly increasing the weight and cost of the displays. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is a front plan view of a tiled, flat-panel display according to one embodiment of the present invention;  
         [0011]    [0011]FIG. 2 is a back plan view of the display in FIG. 1 during fabrication in accordance with one embodiment of the present invention;  
         [0012]    [0012]FIG. 3 is a back plan view of the display of FIG. 2 after fabrication according to one embodiment of the present invention;  
         [0013]    [0013]FIG. 4 a  is an enlarged partial cross-sectional view, taken generally along the line  4 - 4 , of a portion of the embodiment of the present invention shown in FIG. 3 under one type of stress;  
         [0014]    [0014]FIG. 4 b  is an enlarged partial cross-sectional view, taken generally along the line  4 - 4 , of a portion of the embodiment of the present invention shown in FIG. 3 under a different type of stress; and  
         [0015]    [0015]FIG. 5 is an enlarged cross-sectional view taken generally along the line  4 - 4  in FIG. 3.  
     
    
     DETAILED DESCRIPTION  
       [0016]    Referring to FIG. 1, in accordance with one embodiment of the present invention, a tiled, flat-panel display  10  may include an optical integrator  25  having a front surface  30 . In addition, a frame  12  may surround the display  10 .  
         [0017]    A viewer observes an image on the display  10  through the front surface  30  of the optical integrator  25 . That is, the front surface  30  of the display  10  may have light emitted through it. The optical integrator  25  may be made of a substantially transparent material such as glass. The frame  12  may be made of a supportive material, such as a plastic or a metal, which may reduce the tendency of the display  10  to twist or bend at the periphery.  
         [0018]    Tiling of individual display elements  16  may occur during fabrication, as shown in FIG. 2. The plurality of display elements  16 , on the back surface  28  of the display  20 , may ultimately create the image observed by the viewer through the front surface  30  of the display  10 . The display elements  16  emit visible light through the front surface  30  (FIG. 1). The individual display elements  16  that make up the tiled, flat-panel display  10  may be liquid crystal, field emission, plasma, or electroluminescent displays, as examples.  
         [0019]    Individual display elements  16  may be square, rectangular, or another geometric shape. However, in one embodiment of the invention, the display elements  16  may be of the same size and geometric shape.  
         [0020]    Weak points or seams  18  known as stress risers may develop when the display elements  16  combine to form the composite display  10 . Without additional support, a bending stress placed on the display  10  may be concentrated on the optical integrator  25  at the seams  18 . This concentration of stress may result in catastrophic failures. For example, a bending stress may provide the potential for the initiation and propagation of cracks in the display  10 . Thus, the optical integrator  25  may have a tendency to break at the seams  18  when subjected to a bending force.  
         [0021]    In one embodiment of the invention, each display element  16  may be adjacent to at least two other display elements  16  to form seams  18  in both the vertical and horizontal directions. Thus, an increased number of display elements  16  provide an increased number of seams  18  and a decrease in the mechanical stability of the display  10 . Consequently, the larger the display  10 , the greater the potential for the optical integrator  25  to break at the seams  18  especially when subjected to a non-peripheral stress.  
         [0022]    A plurality of vertical straps  20  and horizontal straps  22  may attach to the back surface  28  of the display  10  as shown in FIG. 3. In one embodiment of the invention, the straps  20  and  22  may bridge the seams  18  that create mechanical weakness in the display  10 . That is, each one of the straps  20  and  22  may be attached to a portion of each of two adjacent display elements  16  so that the straps  20  and  22  lie across the seams  18 . In one embodiment, straps  20  and  22  may be adhesively secured to the elements  16 . Moreover, the straps  20  and  22  may be positioned over the seams  18  so that they are perpendicular to each other.  
         [0023]    To further mechanical stability and overall strength of the display  10 , the straps  20  and  22  may connect to the frame  12  by a plurality of joints  24 . In addition, the vertical straps  20  and the horizontal straps  22  may also connect to each other by a plurality of joints  26 . In one embodiment of the invention, the straps  20  and  22  may be attached to each other by an adhesive, for example. Additionally, the straps  20  and  22  may also be adhesively attached to the frame  12 . However, the straps  20  and  22  may be unconnected to one another or all of the straps  20  and  22  may be formed as one integral piece.  
         [0024]    The above-described arrangement of the straps  20  and  22  may contribute to the stability of the display  10  by providing a mechanical interconnection between adjacent display elements  16 . Moreover, the positioning of the straps  20  and  22  may redistribute stress from the optical integrator  25  to the straps  20  and  22 . Thus, the attachments and positioning of the straps  20  and  22  may diminish the stress placed on the optical integrator  25  and hence the tendency of the display  10  to break.  
         [0025]    In one embodiment of the invention, two adjacent display elements  16  are positioned between the optical integrator  25  and one of the straps  20 , as shown in FIGS. 4 a  and  4   b.  The vertical strap  20  lies across the seam  18  between the two display elements  16  where it is adhered to a portion of each of the back surfaces  28  of the adjacent display elements  16 , according to one embodiment. Although not shown for purposes of clarity, the horizontal straps  22  may be similarly positioned across the seams  18  between adjacent display elements  16 .  
         [0026]    Stress concentrations placed on the display  10  around the seams  18  may be redistributed as tension in the straps  20  or  22 , as shown in FIG. 4a. The display  10  may be subjected to a bending stress “A” that bends the display  10  forward relative to the frame  12 , toward the front surface  30  of the optical integrator  25 . Without the straps  20  and  22 , bending stress A may cause the optical integrator  25  to crack at the seams  18 . However, the straps  20  and  22  may limit the degree to which the display  10  may bend in response to the stress A. That is, the bending stress A placed on the display  10  may be redistributed as a tensional stress “B” placed on the strap  20  or  22 . Thus, the strap  20  or  22  may significantly reduce the concentration of the bending stress A placed on the optical integrator  25  at the seam  18 .  
         [0027]    Stress concentrations placed on the display  10  around the seams  18  may also be redistributed as compression, as shown in FIG. 4b. The display  10  may be subjected to bending stress “C” that bends the display  10  backward, toward the back surface  28  of the display  10 . Thus, bending stress C is opposite in direction to that of bending stress A (FIG. 4a). Again, the degree to which the optical integrator  25  and the display elements  16  may be subjected to bending stress C may be limited by the presence of the strap  20  or  22 . In this case, the bending stress C placed on the display  10  around the seam  18  may be redistributed as compression “D” placed on the strap  20  or  22 . Thus, the redistribution of bending stress C to compression D may significantly reduce the concentration of stress placed on the display  10 .  
         [0028]    In sum, the redistribution of bending stress to either tension or compression may decrease the tendency of the display  10  to fail at the seams  18 .  
         [0029]    In one embodiment of the present invention, straps  20  may attach across every vertical seam  18  between display elements  16  in the display  10 , as shown in FIG. 5. The straps  22  may be similarly situated over every horizontal seam  18 , in one embodiment. Thus, a non-peripheral bending force, in either direction, may be transferred from the optical integrator  25  over the entire back surface  28  of the display, via the straps  20  and  22 . Moreover, the combination of the vertical straps  20  and horizontal straps  22  at the juncture of vertical and horizontal seams  18  may significantly redistribute bending stress at these points to improve the integrity of the display  10 . Lastly, the frame  12  may reduce the tendency of the display  10  to twist or bend at the periphery. Taken together, the vertical straps  20 , the horizontal straps  22  and the frame  12  may provide sufficient mechanical strength to significantly consume many types of bending and twisting stresses that may lead to cracking or other failures of the display  10 . In turn, this may allow for the construction of a large array, tiled, flat-panel display that is lightweight yet sturdy.  
         [0030]    While the present invention has been described with respect to a limited number of embodiments, those skilled in the art will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of this present invention.