Abstract:
A tiled display may include subpixels that may be partially occluded by an overlaying matrix. The matrix hides the joints between adjacent tiles. The partial occlusion of one subpixel of a pixel may result in chromatic shifts and/or luminance reduction. The partially occluded subpixel may be compensated for by providing an extra light producing subpixel of the same color on the opposite side of the matrix opening.

Description:
BACKGROUND 
     This invention relates generally to tiled displays made up of a plurality of tiles that collectively display a composite image. 
     In most tiled displays, a matrix overlays the individual tiles which collectively form the display. The matrix generally hides or occludes the joint between adjacent tiles. Each tile may include one or more pixels. Each pixel in turn may be formed by a plurality of color producing elements. The color producing elements may produce the three colors associated with conventional color spaces such as the red green blue (RGB) color space as one example. 
     In some cases, the matrix overlaying the pixels may occlude one or more colors produced by the color producing elements. This may result in luminance loss or chromatic shifts. For example, in a red green blue system, if a blue subpixel of a particular pixel is occluded at a particular viewing angle, the overall pixel may appear shifted towards yellow. Also, the resulting reduction in the blue light may result in loss of luminance to the viewer. 
     Thus, from particular viewing angles, the display may appear chromatically shifted or luminance levels may be lost at least around edges adjacent to the matrix. 
     Displays that may be partially occluded by the matrix may be described as having an aperture parallax limit. In other words, at some angles, through the aperture formed by the matrix into one or more pixels, there may be an angle beyond which the displayed image may be distorted. The distortion may appear as a luminance reductions or chromatic shift as two examples. 
     Thus, there is a need for a way to improve distortions that arise in tiled displays. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic depiction of one embodiment of the present invention; 
     FIG. 2 is a top plan view of the display shown in FIG. 1 before the matrix is applied; and 
     FIG. 3 is an enlarged, partial, top plan view of the embodiment shown in FIG.  1 . 
    
    
     DETAILED DESCRIPTION 
     Referring to FIG. 1, a tiled display  10  may include a layer  18  which has formed therein a plurality of color producing elements  20 ,  22  and  24 . In one embodiment, the elements  20  produce red light, the element  24  produces green light and the elements  22  produce blue light. The color producing elements  20 ,  22  and  24  may be light emissive elements such as inorganic or organic light emitting devices (OLEDs) or field emissive devices as two examples. As another example, the elements  20 ,  22  and  24  may be absorptive or contrast enhancing elements that alter or modulate light passing through them, such as liquid crystal display (LCD) devices. Thus, each element  20 ,  22  or  24  “produces” light of a particular color for example by emitting, selectively passing an absorbing light. 
     A variety of color spaces may be utilized to form the display  10 . In one embodiment, a red green blue (RGB) color gamut is utilized but other known color gamuts may be used as well. In conventional color gamuts, three different color producing elements or subpixels form an individual pixel. By altering the mix of colors produced by the color producing elements  20 ,  22  and  24 , the user can perceive an overall scene made up of a plurality of pixels of the desired colors. 
     In a tiled display  10 , a plurality of display tiles  30   a-h  may be butted together, as illustrated in FIG.  2 . The joint  44  shown between adjacent tiles  30  may be occluded by the matrix  12  shown in FIG.  1 . The matrix  12  generally functions to occlude the joint  44  in an non-obtrusive fashion. 
     As illustrated in FIG. 3, the matrix  12  not only covers the joint  44  but also divides each tile  30 , which may include a large number of pixels, into pixel-sized openings  14 . Thus, a viewer may not notice that the overall display  10  is made up of a plurality of tiles  30  including a large number of pixels defined by apertures  14  in the matrix  12 . 
     The tiles  30  may be unified by a substantially transparent sheet  16  shown in FIG.  1 . The sheet  16  may be a glass sheet in one embodiment. The sheet  16  spaces the layer  18  from the matrix  12 . 
     In one embodiment, shown in FIG. 3, the matrix  12  may be formed of a plurality of intersecting, perpendicular strips  32  that define a plurality of pixel-sized openings  14  over each tile  30 . The viewer perceives the image from the display  10 , not as a collection of images created through the openings  14 , but ideally as a unitary display image. 
     However, a parallax effect may result when a viewer is positioned at an angle with respect to an opening  14 . For example, a viewer may view a pixel made up of subpixels formed by the red  20   b , green  24  and blue  22   a  elements, from the position, as shown in FIG. 1, A. The viewer may have only an occluded view of the red light producing element  20   b . As a result, a luminance loss and/or a chromatic shift may result. However, by including an extra red color producing element  20   a  on the opposite side of the opening  14 , the partial loss of red light from the element  20   b  may be made up by the addition of red light from the element  20   a . Thus, the viewer sees the additional element  20   a  along the line of sight C even through the line of sight B is partially occluded by the matrix  12 . 
     Similarly, a viewer viewing from the opposite side of the opening  14  may have only an occluded view of the blue color producing element  22   a . However, this occlusion may be overcome because the extra blue color producing element  22   b  may be visible in such case. 
     When a pixel made up of the elements  20   b ,  24  and  22   a  is viewed straight on, the viewer may not view the elements  22   b  and  22   a  (which, in such case, are unnecessary). When the viewer views from an angle that causes occlusion of either the element  22   a  or the element  20   b , the additional element  20   a  or  22   b  may then become visible and may compensate for chromatic shift and/or luminance loss resulting from the parallax problem. 
     In some embodiments, the extra blue element  22   b  and the extra red element  20   a  need not be of the same size as the elements  20   b  and  22   a . Since, generally, the elements  20   b  and  22   a  are only partially occluded, only a partial compensating light source may be needed in some embodiments. 
     In some embodiments of the present invention, the red color producing element  20   a  and the red color producing element  20   b  may be driven by the same red color driver  24 . Similarly, a blue color driver  26  may drive both blue color producing elements  22   a  and  22   b  so separate drive systems are not needed for the extra elements  20   a  and  22   b . In addition, in such a system, if the lines are of similar lengths, the elements  22   b  and  22   a  may be driven at exactly the same time as the elements  22   a  and  20   b . A green color element  24 , which in one embodiment may be centrally located, may driven by a green driver  28 . 
     Of course, the orientation of the color producing elements  20 ,  22  and  24  may be changed in other embodiments. In addition, different colors may be utilized in systems which use different color spaces. 
     Since the added elements  20   a  and  22   b  are generally completely occluded when the display  10  is viewed straight on, the inclusion of these extra elements  22   b  and  20   a  may not significantly increase the size of a display  10  or increase the size of the matrix  12 , in some embodiments. Thus, the luminance and/or chrominance roll off may be improved without significantly increasing display  10  or matrix  12  size, in some embodiments of the present invention. 
     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.