Abstract:
An emissive display system includes a matrix of pixels. The matrix of pixels can be comprised of two or more elements. The two or more elements have different areas from each other. The different areas allow the elements to be driven at similar or preferred drive biases and energies despite the different materials utilized to manufacture the elements.

Description:
FIELD OF THE INVENTION 
   The present application relates to visual displays. More particularly, the present application relates to emissive displays having pixel elements sized to optimize efficiency, luminance, chromaticity and lifetime. 
   BACKGROUND OF THE INVENTION 
   Display devices have utilized a variety of techniques to provide dynamic or static images. According to one type of display, an array of pixels emit colored light to achieve an image discernable by an operator. Such emissive displays can utilize pixels comprised of organic light emitting diode (OLED) and polymer light emitting diode (PLED) elements. For a conventional color display, each color pixel is comprised of at least three OLED or PLED elements. 
   With reference to  FIG. 1 , a conventional pixel  20  for a conventional display includes a red element  22 , a blue element  24  and a green element  26 . As shown in  FIG. 1 , elements  22 ,  24 , and  26  have essentially the same area with respect to each other. Elements  22 ,  24 , and  26  can be patterned according to various photolithographic pattern technologies. Elements  22 ,  24 , or  26  can be PLED or OLED elements or other emissive elements. U.S. Pat. No. 6,013,538, U.S. Pat. No. 6,013,982 and U.S. Pat. No. 6,023,259 describe OLED elements. 
   According to conventional systems, element  22  emits a first particular color, element  24  emits a second particular color and element  26  emits a third particular color. Elements  22 ,  24 , and  26  each contain unique materials with respect to each other so that they emit the first, second or third color, respectively, in response to a drive signal. However, certain materials emit brighter or higher luminance light than materials associated with other colors in response to the same drive signal. Accordingly, prior art systems have driven weaker color elements at higher voltages relative to the others to provide the appropriate luminance and chromaticity for pixel  20 . 
   Driving weaker elements harder than others accelerates the degradation of those weaker color elements. For example, if element  22  is driven harder than element  26 , element  22  will degrade and eventually fail before element  26 . Therefore, the need to drive one of elements  22 ,  24 , and  26  with more energy than other elements leads to a premature failure of the display. 
   Thus, there is a need for an emissive display having pixels comprised of elements which are driven equally. Further still, there is a need for a display which addresses efficiency, luminance, chromaticity and lifetime. Even further still, there is a need for a pixel having OLED or PLED elements optimized for operation in a most efficient operating region. 
   SUMMARY OF THE INVENTION 
   An exemplary embodiment relates to an avionic including a plurality of pixels. The pixels are comprised of a plurality of emitting elements. The emitting elements have a first element capable of emitting a first color and a second element capable of emitting a second color. The first element has a first area and the second element has a second area. The first area is larger than the second area. 
   Another exemplary embodiment relates to a display. The display includes a matrix of color pixels. The color pixels are comprised of a first element capable of providing a first color, a second element capable of providing a second color, and a third element capable of providing a third color. The first color is different than the second color and the third color. The second color is different than the third color. The first element has a first area, and the second element has a second area. The first area is larger than the second area. 
   Still another exemplary embodiment relates to a pixel for a display. The pixel includes a first element capable of providing a first color, a second element capable of providing a second color, and a third element capable of providing a third color. The first color is different than the third color and the second color. The second color is different than the third color. The first element has a first area, and the second element has a second area. The first area is larger than the second area. 
   Still another exemplary embodiment relates to a display. The display includes a matrix of color pixels. The color pixels are comprised of a first means for providing a first color, a second means for providing a second color, and a third means for providing a third color. The first color is different than the second color and the third color. The second color is different than the third color. The first element has a first area, and the second element has a second area. The first area is larger than the second area. 
   Still another exemplary embodiment relates to a method of manufacturing a display. The display includes a number of pixels. The method includes providing a first emissive element, providing a second emissive element and providing a third emissive element. The first emissive element is capable of emitting a first color, and the second emissive element is capable of emitting a second color. The third emissive element is capable of emitting a third color. The first color is different than the second and third colors. The second color is different than the third color. The first emissive element has a first area and the second emissive element has a second area. The first area is larger than the second area. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The exemplary embodiments will hereafter be described with reference to the accompanying drawings, wherein like numerals denote like elements, and: 
       FIG. 1  is a schematic block diagram of a conventional pixel for use in an emissive display; 
       FIG. 2  is a schematic block diagram of a display system including a matrix of pixels, in accordance with an exemplary embodiment; 
       FIG. 3  is a more detailed schematic view of a pixel in the matrix illustrated in  FIG. 2 , in accordance with a first exemplary embodiment; 
       FIG. 4  is a more detailed schematic view of a pixel in the matrix illustrated in  FIG. 2 , in accordance with a second exemplary embodiment; 
       FIG. 5  is a more detailed schematic of a pixel in the matrix illustrated in  FIG. 2 , in accordance with a third exemplary embodiment; 
       FIG. 6  is a more detailed schematic view of a pixel in the matrix of  FIG. 2 , in accordance with a fourth exemplary embodiment; 
       FIG. 7  is a more detailed schematic view of a pixel in the matrix illustrated in  FIG. 2 , in accordance with a fifth exemplary embodiment; 
       FIG. 8  is a more detailed schematic view of a pixel in the matrix illustrated in  FIG. 2 , in accordance with a sixth exemplary embodiment; 
       FIG. 9  is a more detailed schematic view of a pixel in the matrix illustrated in  FIG. 2 , in accordance with a seventh embodiment; 
       FIG. 10  is a more detailed schematic view of a pixel for the matrix illustrated in  FIG. 2 , in accordance with an eighth exemplary embodiment; and 
       FIG. 11  is a more detailed schematic view of a pixel for the matrix illustrated in  FIG. 2 , in accordance with a ninth exemplary embodiment. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   With reference to  FIG. 2 , a display system  50  includes a matrix  52  of pixels  54 . Display system  50  can be utilized in a variety of applications. In one embodiment, system  50  is an avionic display in which picture quality and product lifetime are important design parameters. 
   Pixels  54  are driven by electrical signals provided via conductive bars  56  and  58 . Conductive bar  56  drives column signals in accordance with color signals received on conductive lines  60 ,  62 , and  64 . Similarly, conductive bar  58  provides row color signals provided on conductive lines  70 ,  72 , and  74 . 
   Conductive lines  60 ,  62 , and  64  are configured in illuminate or activate colors such as red, green, and blue in pixels  54 . Alternatively, other colors can be represented. The color signals are provided via conductive lines  60 ,  62 , and  64  to drive column signals for matrix  52 . 
   Similarly, conductive lines  70 ,  72 , and  74  drive new color signals for conductive bar  58 . The row color signals can represent colors, such as red, green and blue. Lines  60 ,  62 , and  64  and  70 ,  72 , and  74  are coupled in accordance with a conventional scheme which causes pixels  54  to emit a particular color. The conventional scheme can be for both active and passive matrices. 
   With reference to  FIG. 3 , a pixel  110  can be substituted for any of pixels  54  of matrix  52 . Pixel  110  includes an element  112 , an element  114 , and an element  116 . Element  112  can emit a particular color such as blue. Element  114  can emit a particular color such as green, and element  116  can emit a particular color such as red. Unlike conventional pixels ( FIG. 1 ), pixel  110  includes elements  112 ,  114 , and  116  which are different sizes with respect to each other. 
   As shown in  FIG. 3 , element  112  has an area between the area of element  114  and element  116 . Element  116  has an area greater than element  114 . 
   Various dimensions and arrangements for elements  112 ,  114  and  116  can be utilized. Although shown with element  114  (the smallest sized element) positioned between element  112  (the medium sized element) and element  116  (the longest sized element), other arrangements can be utilized. In fact, any of the arrangements shown in the various figures can be rotated 90 degrees, flipped about a center horizontal axis, flipped about a center vertical axis or flipped about a vertical or horizontal axis on sides of pixel  110 . The arrangements shown in the figures are exemplary arrangements only. 
   In a preferred embodiment, pixel  110  has a 90,000 square micron area having dimensions of 300 microns by 300 microns. Each of elements  112 ,  114 , and  116  has a height of 300 microns. Element  112  has a width of 90 microns. Element  114  has a width of 60 microns and element  116  has a width of 150 microns. Alternatively, pixel  110  can be designed so that element  114  has a width of one half of element  116  and element  112  has a width between the width of element  114  and element  116 . (Element  114  has an area or a width of X; element  116  has an area or a width of 2X and element  112  has an area or width between 1X and 2X.) The above description is for a preferred embodiment only and the claims should be construed to cover any combination of relative sizes and colors unless explicitly required by the claims or the prior art. 
   The dimensions associated with pixel  110  can be chosen in accordance with various design criteria. Elements  112  and  114  and  116  can be lithographically patterned to have area or widths to compensate for weaker color elements such as element  116 . As an example, if element  116  is a red element, it must be larger to have the same luminance at the same drive voltage as elements  114  and  112 . Similarly, element  112  must have an area larger than element  114  to have the same luminance at the same drive voltages. In this way, pixel  110  includes elements which are driven relatively equally to increase lifetime and efficiency of pixel  116  without jeopardizing luminance and chromaticity. Although elements  112 ,  114  and  116  are discussed as having the same luminance, elements  112 ,  114  and  116  do not necessarily have to have the same luminance depending upon design considerations and display criteria. In fact, elements  112 ,  114  and  116  can have slightly more or less luminance than each other according to display preferences. 
   Elements  112 ,  114 , and  116  can be organic light emitting diodes or polymer light emitting diodes. Various manufacturing techniques can be utilized to pattern and fabricate elements  112 ,  114 , and  116 . The present application is not limited to any particular method for manufacturing elements  112 ,  114 , and  116 . Further, elements  112  and  114 , or elements  110  and  112  can have the same area or dimensions rather than the differing dimensions shown in  FIG. 3 . 
   With reference to  FIG. 4 , a pixel  130  is substantially similar to pixel  110  discussed with reference to  FIG. 3 . However, pixel  130  is comprised of a first element  134 , a second element  132  and a third element  136 . Element  136  is similar to element  116 . Element  132  is similar to element  112 . Element  134  is similar to element  114 . However, elements  132  and  134  have different heights from each other and from the height of element  136 . The configuration in  FIG. 4  has elements  134  and  132  having the same widths from left to right as the width of element  136  and different heights to achieve the appropriate area for each element. 
   With reference to  FIG. 5 , a pixel  140  is similar to pixel  110 . However pixel  140  includes a first element  144 , a second element  142 , and a third element  146 . Third element  146  has an L-shape pattern to achieve a greater area than elements  142  and  144 . Again the ratio of areas for elements  142 ,  144 , and  146  can be similar to elements  112 ,  114  and  116  discussed with reference to  FIG. 3 . 
   With reference to  FIG. 6 , a pixel  150  is similar to pixel  140 . However, pixel  150  includes an L-shaped element  156 , an L-shaped element  154  and a square shaped element  152 . The ratio of areas for elements  152 ,  154 , and  156  can be similar to the areas given for elements  114 ,  112  and  116 , respectively. 
   With reference to  FIG. 7 , a pixel  160  is similar to pixel  140 . However, pixel  160  includes a triangular element  164 , a trapezoidal element  162 , and a triangular element  166 . The ratio of areas between elements  162 ,  164 , and  166  can preferably be similar to the areas given for elements  112 ,  114 , and  116 . 
   With reference to  FIG. 8 , a pixel  200  is similar to pixel  110 . However, pixel  200  has a circular shape preferably having an area of approximately 90,000 square microns. Pixel  200  includes a ring shaped element  212  similar to element  112  in  FIG. 3 , a ring shaped element  214  similar to element  114  in  FIG. 3  and a circular element  216  similar to element  116 . Preferably, elements  212 ,  214 , and  216  are concentric to each other and can have a ratio of areas similar to elements  112 ,  114 , and  116 . 
   With reference to  FIG. 9 , a pixel  220  includes a ring shaped element  222 , an oval shaped element  224  and an oval shaped element  226 . Elements  222 ,  224 , and  226  can have a ratio of areas similar to elements  212 ,  214 , and  216  discussed with reference to  FIG. 8 . 
   With reference to  FIG. 10 , a pixel  230  is similar to pixel  200  and includes a ring shaped element  232 , a D-shaped element  234  and a D-shaped element  236 . Elements  232 ,  234 , and  236  can have a ratio of areas similar to elements  212 ,  214 , and  216  discussed with reference to  FIG. 8 . 
   With reference to  FIG. 11 , a pixel  240  is similar to pixel  230  and includes a U-shaped element  242 , a rectangular element  244 , and a U-shaped element  246 . Elements  242 ,  244 , and  246  can have a ratio of areas similar to elements  112 ,  114 , and  116 . 
   Although various particular configurations and shapes for elements are discussed with reference to  FIGS. 2–11 , other configurations and shapes can be utilized. For example, circles, semicircles, D-shaped elements, L-shaped elements, squares, trapezoids, and other polygons can all be used in a variety of configurations. Further, although only circular and square shaped pixels are shown, rectangular, oval, and other shaped pixels can also be formed. 
   It is understood that while the detailed drawings, specific examples, material types, thicknesses, dimensions, and particular values given provide a preferred exemplary embodiment of the present invention, the preferred exemplary embodiment is for the purpose of illustration only. The method and apparatus of the invention is not limited to the precise details and conditions disclosed. Various changes may be made to the details disclosed without departing from the spirit of the invention which is defined by the following claims.