COLOR SETS FOR LOW RESOLUTION DITHERING IN REFLECTIVE COLOR DISPLAYS

• US 20160091770A1
• Filed: 09/25/2015
• Published: 03/31/2016
• Est. Priority Date: 09/26/2014
• Status: Active Grant

• Current Assignee: E Ink Corporation (E Ink Holdings Incorporated)
• Original Assignee: E Ink Corporation (E Ink Holdings Incorporated)
• Inventors: Bouchard, Alain, Telfer, Stephen J.
• Granted Patent: US 10,353,266 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G02F 2001/1678 characterised by the composition or particle type
• CPC Class Codes: G02F 2201/52 RGB geometrical arrangements
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2340/06 Colour space transformation
• 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 3/344 based on particles moving in a fluid or in a gas, e.g. electrophoretic devices electrophoretic devices per se G02F1/167

Abstract

The present invention provides for a method of rendering an image on a reflective display wherein each pixel is capable of rendering a limited number of colors, each of which is rendered by predetermined set of waveforms stored in a waveform lookup table. Furthermore, the present invention provides for a method for rendering an image using such colors, having been chosen for optimal color rendition. This invention further provides for rendering a color image formed from a plurality of pixels on a reflective display wherein each pixel has a color selected from the group consisting of at least: red, green, blue, cyan, magenta, yellow, black and white.

Claims

1. An electrophoretic display comprising a plurality of pixels for generating a color image, each pixel capable of rendering no less than 8 colors and no more than 32 colors, wherein the 8 colors are:

red, green, blue, cyan, magenta, yellow, white and black.

2. The electrophoretic display of claim 1, wherein the colors red, green and blue each have an optical density measurable at three wavelengths, 650 nm, 550 nm, and 450 nm, wherein:

the optical density of the color red, when measured at 650 nm;

is at least 0.2 OD lower than the average of its OD when measured 550 nm and 450 nm,

and is at least 0.1 OD lower than its OD when measured at either 550 nm or 450 nm;

the optical density of the color green when measured at 550 nm;

is at least 0.2 OD lower than the average of its OD when measured at 650 nm and 450 nm,

and is at least 0.1 OD lower than its OD when measured at either 650 nm or 450 nm; and

the optical density of the color blue when measured at 450 nm;

is at least 0.2 OD lower than the average of its OD when measured at 650 nm and 550 nm,

and is at least 0.1 OD lower than its OD when measured at either 650 nm or 550 nm.

3. The electrophoretic display of claim 2, wherein the colors cyan, magenta and yellow each have an optical density measurable at three wavelengths, 650 nm, 550 nm, and 450 nm, wherein:

the optical density of the color cyan, when measured at 650 nm;

is at least 0.2 OD higher than the average of its OD when measured 550 nm and 450 nm,

and is at least 0.1 OD higher than its OD when measured at either 550 nm or 450 nm;

the optical density of the color magenta when measured at 550 nm;

is at least 0.2 OD higher than the average of its OD when measured at 650 nm and 450 nm,

and is at least 0.1 OD higher than its OD when measured at either 650 nm or 450 nm; and

the optical density of the color yellow when measured at 450 nm;

is at least 0.2 OD higher than the average of its OD when measured at 650 nm and 550 nm,

and is at least 0.1 OD higher than its OD when measured at either 650 nm or 550 nm.

4. The electrophoretic display of claim 3, wherein the colors black and white each have an optical density measurable at three wavelengths, 650 nm, 550 nm, and 450 nm, wherein:

the optical densities of the color black, when measured at 650 nm, 550 nm and 450 nm do not differ by more than 0.2 OD; and

the optical densities of the color white when measured at 650 nm, 550 nm and 450 nm do not differ by more than 0.2 OD.

5. An electrophoretic display comprising a plurality of pixels for generating a color image, each pixel capable of rendering no less than 16 colors and no more than 32 colors, wherein the 16 colors are:

red, green, blue, cyan, magenta, yellow, white, black, dark yellow, dark magenta, dark cyan, light red, light green, light blue, light gray and dark gray.

6. The electrophoretic display of claim 5, wherein the colors red, green and blue each have an optical density measurable at three wavelengths, 650 nm, 550 nm, and 450 nm, wherein:

the optical density of the color red, when measured at 650 nm;

is at least 0.2 OD lower than the average of its OD when measured 550 nm and 450 nm,

and is at least 0.1 OD lower than its OD when measured at either 550 nm or 450 nm;

the optical density of the color green when measured at 550 nm;

is at least 0.2 OD lower than the average of its OD when measured at 650 nm and 450 nm,

and is at least 0.1 OD lower than its OD when measured at either 650 nm or 450 nm; and

the optical density of the color blue when measured at 450 nm;

is at least 0.2 OD lower than the average of its OD when measured at 650 nm and 550 nm,

and is at least 0.1 OD lower than its OD when measured at either 650 nm or 550 nm.

7. The electrophoretic display of claim 6, wherein the colors cyan, magenta and yellow each have an optical density measurable at three wavelengths, 650 nm, 550 nm, and 450 nm, wherein:

the optical density of the color cyan, when measured at 650 nm;

is at least 0.2 OD higher than the average of its OD when measured 550 nm and 450 nm,

and is at least 0.1 OD higher than its OD when measured at either 550 nm or 450 nm;

the optical density of the color magenta when measured at 550 nm;

is at least 0.2 OD higher than the average of its OD when measured at 650 nm and 450 nm,

and is at least 0.1 OD higher than its OD when measured at either 650 nm or 450 nm; and

the optical density of the color yellow when measured at 450 nm;

is at least 0.2 OD higher than the average of its OD when measured at 650 nm and 550 nm,

and is at least 0.1 OD higher than its OD when measured at either 650 nm or 550 nm.

8. The electrophoretic display of claim 7, wherein the colors black and white each have an optical density measurable at three wavelengths, 650 nm, 550 nm, and 450 nm, wherein:

the optical densities of the color black, when measured at 650 nm, 550 nm and 450 nm do not differ by more than 0.2 OD; and

the optical densities of the color white when measured at 650 nm, 550 nm and 450 nm do not differ by more than 0.2 OD.

9. The electrophoretic display of claim 8, wherein the colors light red, light green and light blue each have an optical density measurable at three wavelengths, 650 nm, 550 nm, and 450 nm, wherein:

the optical density of the color light red, when measured at 650 nm, is at least 0.1 OD lower than the optical density of the color red when measured at 650 nm;

the optical density of the color light green, when measured at 550 nm is at least 0.1 OD lower than the optical density of the color green when measured at 550 nm; and

the optical density of the color light blue, when measured at 450 nm are at least 0.1 OD lower than the optical densities of the color blue when measured at 650 nm, 550 nm and 450 nm, respectively.

10. The electrophoretic display of claim 9, wherein the colors dark cyan, dark magenta and dark yellow each have an optical density measurable at three wavelengths, 650 nm, 550 nm, and 450 nm, wherein:

the optical density of the color dark cyan, when measured at 650 nm, is at least 0.1 OD higher than the optical density of the color cyan when measured at 650 nm;

the optical density of the color dark magenta, when measured at 550 nm, is at least 0.1 OD higher than the optical density of the color magenta when measured at 550 nm; and

the optical density of the color dark yellow, when measured at 450 nm, is at least 0.1 OD higher than the optical density of the color yellow when measured at 450 nm.

11. An electrophoretic display of claim 10, wherein the 32 colors are:

red, green, blue, cyan, magenta, yellow, white, black, dark yellow, dark magenta, dark cyan, light red, light green, light blue, dark red, dark blue, dark green, an intermediate color between green and yellow, an intermediate color between green and cyan, an intermediate color between red and magenta, an intermediate color between red and yellow, an intermediate color between magenta and blue, an intermediate color between cyan and blue, light cyan, light magenta, light yellow, and six intermediate grays between black and white.

12. An electrophoretic display comprising a plurality of pixels for generating a color image, each pixel capable of rendering no less than 8 colors and no more than 16 colors, wherein the 16 colors are:

red, green, blue, cyan, magenta, yellow, white, black, dark yellow, dark magenta, dark cyan, light red, light green, light blue, light gray and dark gray.

13. The electrophoretic display of claim 12, wherein the colors red, green and blue each have an optical density measurable at three wavelengths, 650 nm, 550 nm, and 450 nm, wherein:

the optical density of the color red, when measured at 650 nm;

is at least 0.2 OD lower than the average of its OD when measured 550 nm and 450 nm,

and is at least 0.1 OD lower than its OD when measured at either 550 nm or 450 nm;

the optical density of the color green when measured at 550 nm;

is at least 0.2 OD lower than the average of its OD when measured at 650 nm and 450 nm,

and is at least 0.1 OD lower than its OD when measured at either 650 nm or 450 nm; and

the optical density of the color blue when measured at 450 nm;

is at least 0.2 OD lower than the average of its OD when measured at 650 nm and 550 nm,

and is at least 0.1 OD lower than its OD when measured at either 650 nm or 550 nm.

14. The electrophoretic display of claim 13, wherein the colors cyan, magenta and yellow each have an optical density measurable at three wavelengths, 650 nm, 550 nm, and 450 nm, wherein:

the optical density of the color cyan, when measured at 650 nm;

is at least 0.2 OD higher than the average of its OD when measured 550 nm and 450 nm,

and is at least 0.1 OD higher than its OD when measured at either 550 nm or 450 nm;

the optical density of the color magenta when measured at 550 nm;

is at least 0.2 OD higher than the average of its OD when measured at 650 nm and 450 nm,

and is at least 0.1 OD higher than its OD when measured at either 650 nm or 450 nm; and

the optical density of the color yellow when measured at 450 nm;

is at least 0.2 OD higher than the average of its OD when measured at 650 nm and 550 nm,

and is at least 0.1 OD higher than its OD when measured at either 650 nm or 550 nm.

15. The electrophoretic display of claim 14, wherein the colors black and white each have an optical density measurable at three wavelengths, 650 nm, 550 nm, and 450 nm, wherein:

the optical densities of the color black, when measured at 650 nm, 550 nm and 450 nm do not differ by more than 0.2 OD; and

the optical densities of the color white when measured at 650 nm, 550 nm and 450 nm do not differ by more than 0.2 OD.

16. The electrophoretic display of claim 15, wherein the colors light red, light green and light blue each have an optical density measurable at three wavelengths, 650 nm, 550 nm, and 450 nm, wherein:

the optical density of the color light red, when measured at 650 nm, is at least 0.1 OD lower than the optical density of the color red when measured at 650 nm;

the optical density of the color light green, when measured at 550 nm is at least 0.1 OD lower than the optical density of the color green when measured at 550 nm; and

the optical density of the color light blue, when measured at 450 nm are at least 0.1 OD lower than the optical densities of the color blue when measured at 650 nm, 550 nm and 450 nm, respectively.

17. The electrophoretic display of claim 16, wherein the colors dark cyan, dark magenta and dark yellow each have an optical density measurable at three wavelengths, 650 nm, 550 nm, and 450 nm, wherein:

the optical density of the color dark cyan, when measured at 650 nm, is at least 0.1 OD higher than the optical density of the color cyan when measured at 650 nm;

the optical density of the color dark magenta, when measured at 550 nm, is at least 0.1 OD higher than the optical density of the color magenta when measured at 550 nm; and

the optical density of the color dark yellow, when measured at 450 nm, is at least 0.1 OD higher than the optical density of the color yellow when measured at 450 nm.

18. An electrophoretic display comprising a plurality of pixels for generating a color image, each pixel capable of rendering no less than 8 colors and no more than 64 colors, wherein 2 colors have a C* value less than 5 and 6 colors have a C* value greater than 10.

19. An electrophoretic display of claim 18, wherein the 2 colors having a C* value less than 5 are white and black.

20. An electrophoretic display of claim 18, wherein, of the 6 colors having a C* value greater than 10, one color has h⁰ between 1 and 60 degrees, one color has h⁰ between 60 degrees and 120 degrees, one color has h⁰ between 120 and 180 degrees, one color has h⁰ between 180 and 240 degrees, one color has h⁰ between 240 and 300 degrees, and one color has h⁰ between 300 and 360 degrees.

21. An electrophoretic display comprising a plurality of pixels for generating a color image, each pixel capable of rendering no less than 16 colors and no more than 64 colors, wherein 4 colors have a C* value less than 5 and 12 colors have a C* value greater than 10.

22. An electrophoretic display of claim 21, wherein, of the 4 colors having a C* value less than 5, one color is white, one color is black and two colors are gray tones equally spaced between white and black.

23. An electrophoretic display of claim 21, wherein, of the 12 colors having a C* value greater than 10, two colors have h⁰ between 1 and 60 degrees, two colors have h⁰ between 60 degrees and 120 degrees, two colors have h⁰ between 120 and 180 degrees, two colors have h⁰ between 180 and 240 degrees, two colors have h⁰ between 240 and 300 degrees, and two colors have h⁰ between 300 and 360 degrees.

24. An electrophoretic display comprising a plurality of pixels for generating a color image, each pixel capable of rendering no less than 32 colors and no more than 64 colors, wherein 8 colors have a C* value less than 5 and 24 colors have a C* value greater than 10.

25. An electrophoretic display of claim 24, wherein, of the 8 colors having a C* value less than 5, one color is white, one color is black and six colors are gray tones equally spaced between white and black.

26. An electrophoretic display of claim 24, wherein, of the 24 colors having a C* value greater than 10, three colors have h⁰ between 15 and 45 degrees, one color has h⁰ between 45 degrees and 75 degrees, three colors have h⁰ between 75 and 110 degrees, five colors have h⁰ between 110 and 180 degrees, three colors have h⁰ between 180 and 250 degrees, eight colors have h⁰ between 250 and 345 degrees, and one color has h⁰ between 345 and 15 degrees in a sector that includes h⁰ equal to 360°

.