ELECTRO OPTICAL DEVICE, ELECTRIC APPARATUS AND PIXEL RENDERING METHOD

• US 20160247441A1
• Filed: 02/19/2016
• Published: 08/25/2016
• Est. Priority Date: 02/20/2015
• Status: Active Grant

• Current Assignee: Tianma Microelectronics Company Limited
• Original Assignee: NLT Technologies, Ltd.
• Inventors: HAMADA, Keita, MATSUEDA, Yojiro
• Granted Patent: US 10,032,403 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G09G 2300/0443 with several sub-pixels for the same colour in a pixel, not specifically used to display gradations G09G3/364 takes precedence
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2320/045 Compensation of drifts in the characteristics of light emitting or modulating elements
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2320/103 Detection of image changes, e.g. determination of an index representative of the image change
• CPC Class Codes: G09G 2340/0457 Improvement of perceived resolution by subpixel rendering
• CPC Class Codes: G09G 3/2003 Display of colours specific for liquid crystal displays G09G3/3607
• CPC Class Codes: G09G 3/2044 using dithering
• CPC Class Codes: G09G 3/2059 using error diffusion
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element

Abstract

An electro optical device has a pixel array constituted by pixels arranged in matrix, each pixel including four subpixels, the four subpixels including RGB subpixels and a subpixel of a similar color to a specific color among RGB, and the four subpixels being arranged in two rows and two columns. In each pixel, a first subpixel having the highest emission luminance and a second subpixel having the second highest emission luminance among subpixels needed for white display are arranged on one diagonal line of the pixel, and the other subpixels are arranged on the other diagonal line. The electro optical device has a control unit that executes switching between a first driving condition and a second driving condition in accordance with a color of a pixel to be displayed, the first driving condition in which both the subpixel of the specific color and the subpixel of the similar color are driven to emit light with the first luminance ratio, and the second driving condition in which both the subpixels of the specific color and the similar color are driven to emit light with the second luminance ratio.

Claims

1. An electro optical device comprising:

a pixel array constituted by pixels arranged in matrix, each pixel including four subpixels, the four subpixels including subpixels of colors of R (Red), G (Green) and B (Blue), and a subpixel of a similar color to a specific color, the specific color being a color of subpixel including a light emitting material having a shortest lifetime among the light emitting materials included in the subpixels of colors of R, G and B, respectively, and the four subpixels being arranged in two rows and two columns; and

a control unit that executes switching between a first driving condition in which both the subpixel of the specific color and the subpixel of the similar color are driven to emit light with a first luminance ratio, and a second driving condition in which both the subpixel of the specific color and the subpixel of the similar color are driven to emit light with a second luminance ratio different from the first luminance ratio, as conditions for driving the pixels, in accordance with a color of a pixel to be displayed, and

wherein each of the pixels includes;

a first subpixel having a highest emission luminance and a second subpixel having a second highest emission luminance among subpixels needed to display a white color, both the first subpixel and the second subpixel being arranged on one diagonal line of the pixel; and

a third subpixel having a third highest emission luminance and a fourth subpixel having a lowest emission luminance, both the third subpixel and the fourth subpixel being arranged on another diagonal line of the pixel.

2. The electro optical device according to claim 1, wherein the specific color is deep blue (B2) and the similar color is light blue (B1).

3. The electro optical device according to claim 2, wherein the control unit executes the switching between the first driving condition and the second driving condition depending on whether a position on a chromaticity diagram of the pixel to be displayed is within a first region enclosed by R, G and B1 or within a second region enclosed by R, B1 and B2.

4. The electro optical device according to claim 3, wherein

the first luminance ratio has a low emission luminance for a subpixel of B2 compared to the second luminance ratio, and

the control unit drives the pixels under the first driving condition with the first luminance ratio in a case where the position on the chromaticity diagram of the pixel to be displayed is within the first region, and drives the pixels under the second driving condition with the second luminance ratio in a case where the position on the chromaticity diagram of the pixel to be displayed is within the second region.

5. The electro optical device according to claim 3, wherein the control unit adjusts a luminance ratio of a subpixel of B2 in accordance with a remaining lifetime for the subpixel of B2.

6. The electro optical device according to claim 3, wherein the control unit adjusts a luminance ratio of a subpixel of B2 in accordance with whether the image to be displayed is a still image or a moving image.

7. The electro optical device according to claim 3, wherein the control unit adjusts a luminance ratio of a subpixel of B2 in accordance with a display mode of the image to be displayed.

8. An electric apparatus, comprising, as a display device, an organic electro luminescence device in which the electro optical device according to claim 1 including a subpixel containing an organic electro luminescence material and a circuit unit driving the pixel array of the electro optical device are formed on a substrate.

9. A pixel rendering method in an electro optical device comprising a pixel array constituted by pixels arranged in matrix, each pixel including four subpixels, the four subpixels including subpixels of colors of R (Red), G (Green) and B (Blue), and a subpixel of a similar color to a specific color, the specific color being a color of subpixel including a light emitting material having a shortest lifetime among the light emitting materials included in the subpixels of colors of R, G and B, respectively, and the four subpixels being arranged in two rows and two columns, and

each of the pixels including:

a first subpixel having a highest emission luminance and a second subpixel having a second highest emission luminance among subpixels needed to display a white color, both the first subpixel and the second subpixel being arranged on one diagonal line of the pixel; and

a third subpixel having a third highest emission luminance and a fourth subpixel having a lowest emission luminance, both the third subpixel and the fourth subpixel being arranged on another diagonal line of the pixel, wherein

the method comprises;

extracting a singularity which is to be an end of an image to be displayed in the pixel array; and

making a subpixel emit light with a predetermined value of luminance, the subpixel being in an adjacent pixel located adjacent to the first subpixel having the highest emission luminance or the fourth subpixel having the lowest emission luminance among pixels arranged at the singularity.

10. The pixel rendering method according to claim 9, comprising

in a case where the image is a white dot,

making at least one of the first subpixel having the highest emission luminance and the second subpixel having the second highest emission luminance in an adjacent pixel emit light, the subpixels being adjacent to the fourth subpixel having the lowest emission luminance in a pixel of the white dot.

11. The pixel rendering method according to claim 9, comprising

in a case where the image is a white dot,

making at least one of the fourth subpixel having the lowest emission luminance and the third subpixel having the third highest emission luminance in an adjacent pixel emit light, the subpixels being adjacent to the first subpixel having the highest emission luminance in a pixel of the white dot.

12. The pixel rendering method according to claim 9, comprising

in a case where the image is a white line,

making the first subpixel having the highest emission luminance or the second subpixel having the second highest emission luminance in an adjacent pixel outside the white line emit light, the subpixel being adjacent to the fourth subpixel having the lowest emission luminance in a pixel inside the white line, and making the second subpixel having the second highest emission luminance or the first subpixel having the highest emission luminance in an adjacent pixel outside the white line emit light, the subpixel being adjacent to the third subpixel having the third highest emission luminance in the pixel inside the white line.

13. The pixel rendering method according to claim 9, comprising

in a case where the image is a white line,

making the fourth subpixel having the lowest emission luminance or the third subpixel having the third highest emission luminance in an adjacent pixel outside the white line emit light, the subpixel being adjacent to the first subpixel having the highest emission luminance in a pixel inside the white line, and making the third subpixel having the third highest emission luminance or the fourth subpixel having the lowest emission luminance in an adjacent pixel outside the white line emit light, the subpixel being adjacent to the second subpixel having the second highest emission luminance in the pixel inside the white line.

14. The pixel rendering method according to claim 10, comprising making the first subpixel having the highest emission luminance in the adjacent pixel and the second subpixel having the second highest emission luminance in the adjacent pixel emit light with different values of luminance.

15. The pixel rendering method according to claim 11, comprising making the fourth subpixel having the lowest emission luminance in the adjacent pixel and the third subpixel having the third highest emission luminance in the adjacent pixel emit light with different values of luminance.

16. The pixel rendering method according to claim 9, wherein the specific color is deep blue (B2) and the similar color is light blue (B1).