Color electrophoretic display

• US 8,786,935 B2
• Filed: 05/29/2012
• Issued: 07/22/2014
• Est. Priority Date: 06/02/2011
• Status: Active Grant

• Current Assignee: E Ink Holdings Incorporated
• Original Assignee: SiPix Imaging, Inc. (E Ink Holdings Incorporated)
• Inventors: Sprague, Robert
• Primary Examiner(s): CHOI, WILLIAM C
• Application Number:
  US13/482,913
• Publication Number:
  US 20120307346A1
• Time in Patent Office: 784 Days
• Field of Search: 359/296, 345/107, 430/32, 204/600
• US Class Current: 359/296
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G02F 2203/34 Colour display without the use of colour mosaic filters

Abstract

The present invention is directed to a color display device wherein each of the display cells is filled with an electrophoretic fluid comprising two types of charged pigment particles dispersed in a colored medium. Multiple colors of high quality may be achieved by the present invention.

Claims

1. A display device comprising display cells, wherein each of said display cells is

a) sandwiched between a first layer comprising a common electrode and a second layer comprising a pixel electrode, and

b) filled with a display fluid comprising a first type of pigment particles which is white and a second type of pigment particles which is red, green or blue, and said two types of pigment particles are oppositely charged and are dispersed in a black solvent,

wherein said black solvent comprises non-charged or slightly charged black particles dispersed in a clear and colorless solvent.

2. The display device of claim 1, wherein said white pigment particles are formed from TiO₂.

3. The display device of claim 1, wherein at least one type of the pigment particles are encapsulated pigment particles.

4. The display device of claim 1, wherein said display fluid further comprises a charge control agent.

5. The display device of claim 1, wherein said non-charged or slightly charged black particles are substantially transparent.

6. The display device of claim 1, wherein the non-charged or slightly charged black particles have a zeta potential of <

20.

7. The display device of claim 1, wherein the non-charged or slightly charged black particles are polymeric and are in the form of a transparent polymeric matrix, with dye molecules embedded in the matrix.

8. The display device of claim 1, wherein each display cell defines a sub-pixel and three sub-pixels forms a pixel.

9. A display device comprising display cells, wherein each of said display cells is

a) sandwiched between a first layer comprising a common electrode and a second layer comprising a pixel electrode, and

b) filled with a display fluid comprising a first type of pigment particles which is white and a second type of pigment particles which is red, green or blue, and said two types of pigment particles are oppositely charged and are dispersed in a colored solvent which has a color complementary to the color of the second type of pigment particles,

wherein the colored solvent comprises non-charged or slightly charged colored particles dispersed in a clear and colorless solvent.

10. The display device of claim 9, wherein each display cell defines a sub-pixel and three sub-pixels form a pixel.

11. The display device of claim 9, wherein said display fluid further comprises a charge control agent.

12. The display device of claim 9, wherein said non-charged or slightly charged colored particles are substantially transparent.

13. The display device of claim 9, wherein the non-charged or slightly charged colored particles have a zeta potential of <

20.

14. The display device of claim 9, wherein the non-charged or slightly charged colored particles are polymeric and are in the form of a transparent polymeric matrix, with dye molecules embedded in the matrix.

15. A display device comprising display cells and a white background layer, wherein each of said display cells is

a) sandwiched between a first layer comprising a common electrode and a second layer comprising a pixel electrode and at least one in-pane electrode, and

b) filled with a display fluid comprising a first type of pigment particles which are white and a second type of pigment particles which are red, green or blue, and said two types of pigment particles are oppositely charged and are dispersed in a colored solvent which has a color complementary to the color of the second type of pigment particles,

wherein the colored solvent comprises non-charged or slightly charged colored particles dispersed in a clear and colorless solvent.

16. The display device of claim 15, wherein each display cell defines a sub-pixel and two sub-pixels form a pixel.

17. The display device of claim 15, wherein said display fluid further comprises a charge control agent.

18. The display device of claim 15, wherein said non-charged or slightly charged colored particles are substantially transparent.

19. The display device of claim 15, wherein the non-charged or slightly charged colored particles have a zeta potential of <

20.

20. The display device of claim 15, wherein the non-charged or slightly charged colored particles are polymeric and are in the form of a transparent polymeric matrix, with dye molecules embedded in the matrix.