Tetrachromatic color filter array for reflective display

• US 8,873,129 B2
• Filed: 04/04/2012
• Issued: 10/28/2014
• Est. Priority Date: 04/07/2011
• Status: Active Grant

• Current Assignee: E Ink Holdings Incorporated
• Original Assignee: E Ink Holdings Incorporated
• Inventors: Paolini, Richard J. Jr., Telfer, Stephen J., Bouchard, Alain, Atkinson, John
• Primary Examiner(s): Pham, Thomas K
• Assistant Examiner(s): THOMAS, BRANDI N
• Application Number:
  US13/439,404
• Publication Number:
  US 20120257269A1
• Time in Patent Office: 937 Days
• Field of Search: 359/237, 359/242, 359290-292, 359/295, 359/298, 359/267, 359/268, 359/491.01, 353/84
• US Class Current: 359/296
• CPC Class Codes: G02B 5/201 in the form of arrays
• CPC Class Codes: G02B 5/22 Absorbing filters G02B5/201 - G02B5/208 take precedence
• CPC Class Codes: G02F 1/133514 Colour filters
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G02F 1/1677 Structural association of cells with optical devices, e.g. reflectors or illuminating devices
• CPC Class Codes: G02F 2203/055 wavelength filtering

Abstract

A tetrachromatic color filter array comprises multiple pixels, each of which comprises first, second, third and fourth sub-pixels having first, second, third and fourth hues, P1, P2, P3 and P4 respectively, these first, second, third and fourth hues having first, second and third hue angles, h1, h2, h3 and h4 respectively. The hues of the sub-pixels such that h3 equals h1+(180°±10°) and h4 equals h2+(180°±10°) in the a*b* plane of the La*b* color space.

Claims

1. A color filter array comprising a plurality of pixels, each pixel comprising:

a first sub-pixel having a first hue P1 positioned at a first hue angle h1 in the a*b* plane of the La*b* color space;

a second sub-pixel having a second hue P2 positioned at a second hue angle h2 in said a*b* plane;

a third sub-pixel having a third hue P3 positioned at a third hue angle h3 equal to h1+(180°

±

10°

) in said a*b* plane; and

a fourth sub-pixel having a fourth hue P4 positioned at a fourth hue angle h4 equal to h2+(180°

±

10°

) in said a*b* plane.

2. A color filter according to claim 1 wherein said third hue angle h3 is equal to h1+(180°

±

5°

) and said fourth hue angle h4 equal to h2+(180°

±

5°

) in said a*b* plane.

3. A color filter according to claim 2 wherein said third hue angle h3 is equal to h1+(180°

±

2°

) and said fourth hue angle h4 equal to h2+(180°

±

2°

) in said a*b* plane.

4. A color filter array according to claim 1 wherein hue pairs P1/P3 and P2/P4 are selected from red/cyan, green/magenta and blue/yellow.

5. A color filter array according to claim 1 wherein a first line connecting hue P1 to hue P3 and a second line connecting hue P2 to hue P4 intersect within the a*b* plane of the La*b* color space so as to define angles of not less than about 70°

.

6. A color filter array according to claim 5 wherein said first and second lines define angles of not less than about 80°

.

7. A color filter array according to claim 6 wherein said first and second lines define angles of not less than about 85°

.

8. A color filter array according to claim 1 wherein the line connecting hue P1 to P3 and the line connecting hue P2 to hue P4 intersect near the origin of the a*b* plane of the La*b* color space such that the distance from the origin of the a*b* plane to said intersection is less than about 20% of the shortest of the distances from the origin of the a*b* plane to any one of hues P1, P2, P3, and P4.

9. A color filter array according to claim 1 wherein the angle between hue angle h1 and hue angle h2 in said a*b* plane is from about 70°

to about 110°

.

10. A color filter array according to claim 1 wherein the hue of each sub-pixel in the color filter array has a C* value greater than 5 Δ

E units from the origin of the a*b* plane.

11. An electro-optic display comprising a color filter according to claim 1, a layer of electro-optic material disposed adjacent the color filter capable of changing its optical state upon application of an electric field thereto, and at least one electrode arranged to apply an electric field to the layer of electro-optic material.

12. An electro-optic display according to claim 11 wherein the electro-optic material comprises a rotating bichromal member or electrochromic material.

13. An electro-optic display according to claim 11 wherein the electro-optic material comprises an electrophoretic material comprising a plurality of electrically charged particles disposed in a fluid and capable of moving through the fluid under the influence of an electric field.

14. An electro-optic display according to claim 13 wherein the electrically charged particles and the fluid are confined with a plurality of capsules or micro cells.

15. An electro-optic display according to claim 13 wherein the electrically charged particles and the fluid are present as a plurality of discrete droplets surrounded by a continuous phase comprising a polymeric material.

16. An electro-optic display according to claim 13 wherein the fluid is gaseous.

17. An electronic book reader, portable computer, tablet computer, cellular telephone, smart card, sign, watch, shelf label, and/or flash drive comprising a display according to claim 11.

18. A color filter array according to claim 1 which contains only sub-pixels of said first, second, third and fourth hues.