Electrophoretic display with dual mode switching

• US 20040032389A1
• Filed: 02/14/2003
• Published: 02/19/2004
• Est. Priority Date: 08/16/2002
• Status: Active Grant

• Current Assignee: E Ink California, LLC (E Ink Corporation)
• Original Assignee: SiPix Imaging, Inc. (E Ink Holdings Incorporated)
• Inventors: Liang, Rong-Chang, Chung, Jerry
• Granted Patent: US 7,038,670 B2
• Time in Patent Office: Days
• US Class Current: 345/107
• CPC Class Codes: G02F 1/134363 for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G02F 1/16762 having three or more electrodes per pixel
• CPC Class Codes: G02F 1/1677 Structural association of cells with optical devices, e.g. reflectors or illuminating devices
• CPC Class Codes: G02F 1/1681 having two or more microcells partitioned by walls, e.g. of microcup type
• CPC Class Codes: G09G 2300/0426 Layout of electrodes and connections
• CPC Class Codes: G09G 2300/06 Passive matrix structure, i.e. with direct application of both column and row voltages to the light emitting or modulating elements, other than LCD or OLED
• CPC Class Codes: G09G 2300/08 Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
• CPC Class Codes: G09G 2310/0262 The addressing of the pixel, in a display other than an active matrix LCD, involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependent on signals of two data electrodes
• CPC Class Codes: G09G 2320/02 Improving the quality of display appearance
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• 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 relates to an improved EPD which comprises both the traditional up/down switching and the in-plane switching modes. In other words, the improved EPD has dual switching modes.

The monochrome EPDs of the present invention are capable of displaying highlight color of choice which is different from the text. For example, white background, blue text, and red highlight can be shown in any selected areas of the display. Furthermore, the full color EPDs of the present invention are capable of displaying high contrast images of high color saturation. Both high quality black and white states are possible in the full color displays of the present invention. The EPDs of the present invention do not need complex circuitry design, and are compatible with low cost and high yield roll-to-roll manufacturing processes. The EPD cells of the present invention may have opaque partition walls, or a black matrix top surface of the partition walls or a combination thereof.

Claims

1. An electrophoretic display comprising

a) a top layer comprising a top electrode,

b) a bottom layer comprising a bottom electrode and at least one in-plane electrode, and

c) an array of electrophoretic cells sandwiched between the top and bottom layers and each cell comprising

(i), opaque partition walls,

(ii) a cell background,

(iii) an electrophoretic composition filled therein and comprises only one type of charged pigment particles dispersed in a dyed dielectric solvent or solvent mixture.

2. The electrophoretic display of claim 1 wherein said opaque partition walls are white.

3. The electrophoretic display of claim 1 wherein said opaque partition walls are gray.

4. The electrophoretic display of claim 1 wherein said opaque partition walls are formed from a composition comprising a UV curable material and a filler, dye or pigment.

5. The electrophoretic display of claim 4 wherein said filler is selected from a group consisting of silica, ZnO, TiO₂, BaSO₄, CaCO₃ and polymer particles.

6. The electrophoretic display of claim 4 wherein said filler material is silica or polymer particles.

7. The electrophoretic display of claim 4 wherein said filler material is in the amount of 1-20% by weight of the composition.

8. The electrophoretic display of claim 7 wherein said filler material is in the amount of 2-10% by weight of the composition.

9. The electrophoretic display of claim 1 wherein said opaque partition walls are formed from a composition comprising a radiation curable material and a latent light scattering material.

10. The electrophoretic display of claim 9 wherein said latent light scattering material is a material that is compatible with the radiation curable material before curing but becomes incompatible after curing.

11. The electrophoretic display of claim 9 wherein said latent light scattering material is a thermally or photochemically triggered gas-releasing material.

12. The electrophoretic display of claim 11 wherein said thermally or photochemically triggered gas-releasing material is selected from a group consisting of CO₂ producing carboxylic acids, bicyclic lactones or heterocycles;

CO producing ketones or bicyclic adducts;

SO and SO₂ producing sulfones, sulfonyloxy compounds or heterocycles;

N₂ producing azoalkanes, azides, diazomethanes, N-nitroso compounds, diazo, triazo or tetraazo heterocycles;

COS producing xanthates and O₂ producing endoperoxides.

13. The electrophoretic display of claim 11 wherein said thermally or photochemically triggered gas-releasing material is a phenol, tropolone, pyridine, pyrazine, pyrrole or a halogenated derivative thereof.

14. The electrophoretic display of claim 1 wherein said opaque partition walls are colored.

15. The electrophoretic display of claim 1 wherein the inside surface of the partition walls is of the same color as that of the electrophoretic composition.

16. The electrophoretic display of claim 15 wherein the two sides of a partition wall are of different colors.

37. The electrophoretic display of claim 1 or 17 wherein said charged pigment particles are pigment-containing microparticles.

38. The electrophoretic display of claim 37 wherein said pigment-containing microparticles have a specific gravity matched to that of the dielectric solvent.

17. An electrophoretic display comprising

a) a top layer comprising a top electrode and optionally a top substrate,

b) a bottom layer comprising a bottom-electrode, at least one in-plane electrode and optionally a bottom substrate, and

c) an array of electrophoretic cells sandwiched between the top and bottom layers and each cell comprising

(i) partition walls,

(ii) a black matrix layer on the top surface of the partition walls or on another layer in areas corresponding to the top surface of the partition walls,

(iii) a cell background, and

(iv) an electrophoretic composition filled therein and comprises only one type of charged pigment particles dispersed in a dyed dielectric solvent or solvent mixture.

18. The electrophoretic display of claim 17 wherein said black matrix layer is on the top surface of the partition walls.

19. The electrophoretic display of claim 17 wherein each of said electrophoretic cells comprises a top sealing layer enclosing said electrophoretic composition within each cell.

20. The electrophoretic display of claim 19 wherein said top electrode layer is applied with an adhesive.

21. The electrophoretic display of claim 20 wherein said black matrix layer is between the top-sealing layer and the adhesive layer.

22. The electrophoretic display of claim 20 wherein said black matrix layer is between the adhesive layer and the top electrode layer.

23. The electrophoretic display of claim 17 wherein said black matrix layer is between the top electrode layer and the top substrate.

24. The electrophoretic display of claim 17 wherein said black matrix layer is on top of the top substrate.

25. The electrophoretic display of claim 17 wherein said black matrix layer is between the electrophoretic cells and the bottom electrode layer.

26. The electrophoretic display of claim 17 wherein said black matrix layer is between the bottom electrode layer and the bottom substrate.

27. The electrophoretic display of claim 17 wherein said black matrix layer is on the bottom surface of the bottom substrate.

28. The electrophoretic display of claim 17 wherein said black matrix layer is applied with registration to top surface of the partition walls.

29. The electrophoretic display of claim 17 wherein said black matrix layer is applied by printing, stamping or photolithography.

30. The electrophoretic display of claim 17 wherein said black matrix layer is applied by vapor deposition or sputtering with a shadow mask.

31. The electrophoretic display of claim 17 wherein the optical density of said black matrix layer is higher than 0.5.

32. The electrophoretic display of claim 31 wherein the optical density of said black matrix layer is higher than 1.

33. The electrophoretic display of claim 17 wherein the thickness of the black matrix layer is in the range of from 0.005 μ

m to 5 μ

m.

34. The electrophoretic display of claim 33 wherein the thickness of the black matrix layer is in the range of from 0.01 μ

m to 2 μ

m.

35. The electrophoretic display of claim 17 further comprising a diffuser layer directly or indirectly above the black matrix layer.

36. The electrophoretic display of claim 17 wherein said black matrix layer is a highly crosslinked black matrix layer.

39. The electrophoretic display of claim 17 wherein said partition walls are opaque.

40. The electrophoretic display of claim 39 wherein said partition walls are white opaque.

41. The electrophoretic display of claim 39 wherein said partition walls are gray opaque.

42. The electrophoretic display of claim 17 wherein said partition walls are colored.

43. The electrophoretic display of claim 17 wherein the inside surface of the partition walls is of the same color as the electrophoretic composition.

44. The electrophoretic display of claim 43 wherein the two sides of a partition wall are of different colors.