Color display device and method for reproducing color with an increased number of gradation levels

• US 8,159,509 B2
• Filed: 03/28/2008
• Issued: 04/17/2012
• Est. Priority Date: 03/30/2007
• Status: Active Grant

• Current Assignee: LAPIS Semiconductor Co., Ltd. (ROHM Co., Ltd.)
• Original Assignee: Oki Semiconductor Company Limited (ROHM Co., Ltd.)
• Inventors: Kanou, Hideki
• Primary Examiner(s): Mengistu, Amare
• Assistant Examiner(s): Sharifi-Tafreshi, Koosha
• Application Number:
  US12/057,875
• Publication Number:
  US 20080238952A1
• Time in Patent Office: 1,481 Days
• Field of Search: 345/87, 345/89, 345/690, 345/694, 345/695, 345/698
• US Class Current: 345/690
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 3/2074 using sub-pixels
• CPC Class Codes: G09G 3/3607 for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels display of colours in flat matrix panels other than liquid crystal displays G09G3/2003; grey scales specific for television H04N3/127

Abstract

A color display device has a display screen having pixels arrayed, each of which is composed of primary color sub-pixels capable of reproducing respective primary colors and at least one subsidiary color sub-pixel capable of reproducing gray. While gradation signals are generated and supplied to the primary color sub-pixels on the basis of the primary color components of an image to be displayed, the gradation signal to be supplied to the subsidiary color sub-pixel is generated on the basis of the intensity component of the image. The color display device is attained in which the number of gradation levels can be substantially increased without increasing the number of gradation levels of the primary colors.

Claims

1. A method of controlling a color display device comprising a display screen having a plurality of pixels arranged in an array, each of the plurality of pixels including primary color sub-pixels for reproducing at least respective, three primary colors and at least one subsidiary color sub-pixel for reproducing a color different from the primary colors to increase a number of gradation levels of the primary colors of the primary color sub-pixels, comprising the steps of:

inputting into a processor or generating by the processor an original luminance signal and original color-difference signals determined from an original image which is desired to be displayed on the screen;

generating a primary color data signal for each of the primary color sub-pixels on a basis of the original luminance signal and original color-difference signals by the processor to output the primary color data signal to a timing controller together with the original luminance signal, the primary color data signal indicating a voltage to be applied to the primary color sub-pixel; and

generating by the timing controller a subsidiary color data signal on the basis of the original luminance signal to output the subsidiary color data signal to a source driver of the screen together with the primary color data signals, the subsidiary color data signal indicating a voltage to be applied to the subsidiary color sub-pixel of the pixel having the primary color sub-pixel for which the primary color data signal is generated.

2. The method in accordance with claim 1, wherein the pixel consists of three primary color sub-pixels arranged in a first row and three subsidiary color sub-pixels arranged in a second row next to the first row, and the subsidiary color data signal is generated for the subsidiary color sub-pixel arranged in a same column of the primary color sub-pixel for which the primary color data signal is generated.

3. The method in accordance with claim 1, further comprising the step of separately transferring the original luminance signal and the primary color data signals from each other from the processor to the timing controller.

4. The method in accordance with claim 1, wherein the timing controller generates the subsidiary color data signal referring to correction data indicating suitable luminance of the subsidiary color sub-pixel for the primary color to be reproduced by the primary color data signal.

5. A method of displaying a color at a pixel of a display screen by a combination of at least three primary color sub-pixels for at least respective, three primary colors and at least one subsidiary color sub-pixel for reproducing a color different from the primary colors to increase a number of gradation levels of the primary colors of the primary color sub-pixels, comprising the steps of:

generating an original luminance signal and original color-difference signals determined from an original image which is desired to be displayed on the screen;

generating a primary color data signal for each of the primary color sub-pixels on a basis of the original luminance signal and original color-difference signals, the primary color data signal indicating a voltage to be applied to the primary color sub-pixel; and

generating a subsidiary color data signal on the basis of the original luminance signal, the subsidiary color data signal indicating voltage to be applied to the subsidiary color sub-pixel of the pixel having the primary color sub-pixel for which the primary color data signal is generated;

wherein the pixel consists of three primary color sub-pixels arranged in a first row and three subsidiary color sub-pixels arranged in a second row next to the first row, and the subsidiary color data signal is generated for the subsidiary color sub-pixel arranged in a same column of the primary color sub-pixel for which the primary color data signal is generated.

6. The method in accordance with claim 5, wherein the subsidiary color data signal is generated with reference to correction data indicating a suitable luminance of the subsidiary color sub-pixel for the primary color to be reproduced by the primary color data signal.

7. A color display device comprising:

a display screen having plurality of pixels arranged in an array, each of the plurality of pixels including primary color sub-pixels for reproducing at least respective, three primary colors and at least one subsidiary color sub-pixel for reproducing a color different from the primary colors to increase a number of gradation levels of the primary colors of the primary color sub-pixels;

a processor for receiving or generating an original luminance signal and original color-difference signals determined from an original image which is desired to be displayed on the screen, and for generating a primary color data signal for each of the primary color sub-pixels on a basis of the original luminance signal and original color-difference signals, the primary color data signal indicating a voltage to be applied to the primary color sub-pixel; and

a timing controller for receiving the primary color data signal from the processor together with the original luminance signal, and for generating a subsidiary color data signal on a basis of the original luminance signal to output the subsidiary color data signal to a source driver of the display together with the primary color data signal, the subsidiary color data signal indicating a voltage to be applied to the subsidiary color sub-pixel of the pixel having the primary color sub-pixel for which the primary color data signal is generated.

8. The color display device in accordance with claim 7, wherein each of said plurality of pixels comprises a plurality of the subsidiary color sub-pixels provided in a one-to-one correspondence with the primary color sub-pixels.

9. The color display device in accordance with claim 8, wherein the subsidiary color data signal is generated separately for each of the subsidiary color sub-pixels.

10. The color display device in accordance with claim 7, wherein said data processor separately transfers the original luminance signal and the primary color data signal from each other to said timing controller.

11. The color display device in accordance with claim 7, wherein said data processor is provided with correction data indicating suitable luminance of the subsidiary color sub-pixel for the primary color to be reproduced by the primary color data signal, and the data processor refers to the correction data to generate the subsidiary color data signal.

12. The color display device in accordance with claim 7, wherein the pixel consists of three primary color sub-pixels arranged in a first row and three subsidiary color sub-pixels arranged in a second row next to the first row, and the subsidiary color data signal is generated for the subsidiary color sub-pixel arranged in a same column of the primary color sub-pixel for which the primary color data signal is generated.