Electrophoretic display with in-plane switching

• US 6,885,495 B2
• Filed: 07/16/2002
• Issued: 04/26/2005
• Est. Priority Date: 03/03/2000
• Status: Expired due to Term

• Current Assignee: E Ink California, LLC (E Ink Holdings Incorporated)
• Original Assignee: SiPix Imaging, Inc. (E Ink Holdings Incorporated)
• Inventors: Chung, Jerry, Liang, Rong-Chang, Chen, David
• Primary Examiner(s): Spector, David N.
• Application Number:
  US10/198,729
• Publication Number:
  US 20030035198A1
• Time in Patent Office: 1,015 Days
• Field of Search: 359/296, 345/107
• US Class Current: 359/296
• 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 1/1679 Gaskets; Spacers; Sealing of cells; Filling or closing of cells
• CPC Class Codes: G02F 2201/12 electrode

Abstract

The present invention relates to an improved EPD which comprises the in plane switching mode. More specifically, the EPD of the present invention comprises isolated cells formed from microcups of well defined size, shape and aspect ratio and the movement of the particles in the cells is controlled by the in-plane switching mode. The EPD of the present invention may be produced in a continuous manufacturing process, and the display gives improved color saturation.

Claims

1. An electrophoretic display comprising (1) isolated electrophoretic cells formed from micro cups of well-defined size, shape and aspect ratio wherein said microcups are filled with an electrophoretic composition and the filled microcups are sealed with a sealing layer formed from a sealing composition having a specific gravity lower than that of the electrophoretic composition, and (2) an in-plane switching mode.

2. The electrophoretic display of claim 1 wherein each of said isolated electrophoretic cells has two in-plane electrodes.

3. The electrophoretic display of claim 1 wherein each of said isolated electrophoretic cells has one in-plane electrode.

4. The electrophoretic display of claim 1 wherein the microcups have a top opening ranging from about 10² to about 1×

10⁶ μ

m².

5. The electrophoretic display of claim 4 wherein the microcups have a top opening ranging from about 10³ to about 1×

10⁵ μ

m².

6. The electrophoretic display of claim 1 wherein the microcups have a depth in the range of about 5 to about 200 microns.

7. The electrophoretic display of claim 6 wherein the microcups have a depth in the range of about 20 to about 100 microns.

8. The electrophoretic display of claim 1 wherein the microcups have an opening to total area ratio in the range of from about 0.2 to about 0.95.

59. The electrophoretic display of claim 1 wherein said sealing composition is a radiation, heat or moisture curable composition.

60. The electrophoretic display of claim 1 wherein said sealing composition comprises a material selected from the group consisting of acrylates, methacrylates, styrene, α

-methylstyrene, butadiene, isoprene, allylacrylate, polyvalent acrylate, polyvalent methacrylate, cyanoacrylates, polyvalent vinyl, polyvalent epoxide, polyvalent isocyanate, polyvalent allyl and oligomers or polymers containing crosslinkable functional groups.

61. The electrophoretic display of claim 1 wherein said sealing composition comprises a thermoplastic elastomer.

62. The electrophoretic display of claim 61 wherein said thermoplastic elastomer is a di-block or tri-block copolymer of styrene or α

-methylstyrene.

63. The electrophoretic display of claim 61 wherein said thermoplastic elastomer is SB (poly(styrene-b-butadiene)), SBS (poly(styrene-b-butadiene-b-styrene)), SIS (poly(styrene-b-isoprene-b-styrene)), SEBS (poly(styrene-b-ethylene/butylenes-b-styrene))poly(styrene-b-dimethylsiloxane-b-styrene), poly(α

-methylstyrene-b-isoprene), poly(α

-methylstyrene-b-isoprene-b-α

-methylstyrene), poly(α

-methylstyrene-b-propylene sulfide-b-α

-methylstyrene) or poly(α

-methylstyrene-b-dimethylsiloxane-b-α

-methylstyrene).

9. An electrophoretic display comprising isolated cells formed from microcups of well-defined size, shape and aspect ratio wherein said microcups are filled with an electrophoretic composition comprising charged particles dispersed in a dielectric solvent or solvent mixture and the filled microcups are sealed with a sealing layer formed from a sealing composition having a specific gravity lower than that of the electrophoretic composition and each of said isolated cells comprises a transparent viewing layer on one side and a layer comprising one common electrode and an in-plane electrode on the opposite side.

10. The electrophoretic display of claim 9 wherein each of said isolated cells further comprising a separate background layer.

11. The electrophoretic display of claim 9 wherein said transparent viewing layer is colorless.

12. The electrophoretic display of claim 10 wherein said separate background layer is on top of the layer comprising one common electrode and an in-plane electrode.

13. The electrophoretic display of claim 10 wherein said separate background layer is underneath the layer comprising one common electrode and an in-plane electrode.

14. The electrophoretic display of claim 9 wherein said layer comprising one common electrode and an in-plane electrode serves as a background layer and the in-plane electrode is white or colored.

15. The electrophoretic display of claim 9 wherein the display is a monochrome display.

16. The electrophoretic display of claim 15 wherein said dielectric solvent is clear and colorless.

17. The electrophoretic display of claim 16 wherein said charged particles are of the white color and said cells have a background of one color.

18. The electrophoretic display of claim 17 wherein said background color is black, red, green, blue, yellow, cyan or magenta.

19. The electrophoretic display of claim 16 wherein said charged particles are of one color and said cells have a background of the white color.

20. The electrophoretic display of claim 19 wherein said charged particles are black, red, green, blue, yellow, cyan or magenta.

21. The electrophoretic display of claim 16 wherein said charged particles are of mixed colors in all of said cells which have a background of one color.

22. The electrophoretic display of claim 21 wherein the mixed colors are two or more colors selected from the group consisting of black, white, red, green, blue, yellow, cyan and magenta.

23. The electrophoretic display of claim 22 wherein said background is of a color selected from the group consisting of black, white, red, green, blue, yellow, cyan and magenta.

24. The electrophoretic display of claim 9 wherein said display is a multiple color display.

25. The electrophoretic display of claim 24 wherein said charged particles are of the white color and said cells have background of different colors.

26. The electrophoretic display of claim 24 wherein said charged particles are of the black color and said cells have background of different colors.

27. The electrophoretic display of claim 24 wherein said cells are filled with electrophoretic compositions comprising charged particles of different colors dispersed in a dielectric solvent or solvent mixture and all of said cells have a background of the white color.

28. The electrophoretic display of claim 24 wherein said cells are filled with electrophoretic compositions comprising charged particles of different colors dispersed in a dielectric solvent or solvent mixture and all of said cells have a background of the black color.

29. The electrophoretic display of claim 9 wherein said transparent viewing layer is colored or comprises a color filter.

30. The electrophoretic display of claim 29 wherein each of said isolated cells further comprising a separate background layer which is on top of the layer comprising one common electrode and an in-plane electrode.

31. The electrophoretic display of claim 29 wherein each of said isolated cells further comprising a separate background layer which is underneath the layer comprising one common electrode and an in-plane electrode.

32. The electrophoretic display of claim 29 wherein said layer comprising one common electrode and an in-plane electrode serves as a background layer and the in-plane electrode is white or colored.

33. The electrophoretic display of claim 29 wherein said charged particles are of the white color and said cells have a background of the black color.

34. The electrophoretic display of claim 33 wherein all said cells have the transparent viewing layer of the same color.

35. The electrophoretic display of claim 33 wherein said cells have the transparent viewing layer of different colors.

58. The electrophoretic display of claim 9 wherein a substrate comprising an array of thin film transistors is used as the layer comprising one common electrode and an in-plane electrode.

64. The electrophoretic display of claim 9 wherein said sealing composition is a radiation, heat or moisture curable composition.

65. The electrophoretic display of claim 9 wherein said sealing composition comprises a material selected from the group consisting of acrylates, methacrylates, styrene, α

-methylstyrene, butadiene, isoprene, allylacrylate, polyvalent acrylate, polyvalent methacrylate, cyanoacrylates, polyvalent vinyl, polyvalent epoxide, polyvalent isocyanate, polyvalent allyl and oligomers or polymers containing crosslinkable functional groups.

66. The electrophoretic display of claim 9 wherein said sealing composition comprises a thermoplastic elastomer.

67. The electrophoretic display of claim 66 wherein said thermoplastic elastomer is a di-block or tri-block copolymer of styrene or α

-methylstyrene.

68. The electrophoretic display of claim 66 wherein said thermoplastic elastomer is SB (poly(styrene-b-butadiene)), SBS (poly(styrene-b-butadiene-b-styrene)), SIS (poly(styrene-b-isoprene-b-styrene)), SEBS (poly(styrene-b-ethylene/butylenes-b-styrene))poly(styrene-b-dimethylsiloxane-b-styrene), poly(α

-methylstyrene-b-isoprene), poly(α

-methylstyrene-b-isoprene-b-α

-methylstyrene), poly(α

-methylstyrene-b-propylene sulfide-b-α

-methylstyrene) or poly(α

-methylstyrene-b-dimethylsiloxane-b-α

-methylstyrene).

73. The electrophoretic display of claim 9 wherein said layer comprising one common electrode and an in-plane electrode comprises one common electrode and two in-plane electrodes.

74. The electrophoretic display of claim 9 wherein said layer comprising one common electrode and an in-plane electrode comprises one common electrode and one in-plane electrode.

36. A process for the manufacture of an electrophoretic display having isolated cells formed from microcups having well defined size, shape and aspect ratio, said process comprises

a) forming a layer by coating a radiation curable material over a transparent insulator substrate;

b) forming microcups on the radiation curable material by microembossing or imagewise exposure to radiation;

c) filling the microcups with an electrophoretic composition;

d) sealing the microcups with a sealing composition having a specific gravity lower than that of the electrophoretic composition; and

e) laminating the sealed microcups with a substrate comprising one common electrode and an in-plane electrode over each of said sealed microcups.

37. The process for the manufacture of an electrophoretic display of claim 36 wherein said substrate comprising one common electrode and an in-plane electrode is coated with an adhesive.

40. The process of claim 36 wherein the microcups have a top opening ranging from about 10² to about 1×

10⁶ μ

m².

42. The process of claim 36 wherein said transparent insulator substrate is colorless.

43. The process of claim 42 wherein said cells have a background of the same color and are filled with an electrophoretic composition comprising charged particles of the same color dispersed in a clear colorless dielectric solvent.

44. The process of claim 42 wherein said cells have background of different colors and are filled with an electrophoretic composition comprising charged particles of the same color dispersed in a clear colorless dielectric solvent.

45. The process of claim 42 wherein said cells have a background of the same color and are filled with electrophoretic compositions comprising charged particles of different colors dispersed in a clear colorless dielectric solvent.

50. The process of claim 36 wherein said transparent insulator substrate is colored.

51. The process of claim 50 wherein said cells have a background of the black color and are filled with an electrophoretic composition comprising charged particles of the white color dispersed in a clear colorless dielectric solvent.

52. The process of claim 51 wherein said cells have the transparent insulator substrate of the same color.

53. The process of claim 51 wherein said cells have the transparent insulator substrate of different colors.

69. The process of claim 36 wherein steps (c) and (d) are accomplished by (1) filling a mixture of the sealing composition and the electrophoretic composition, and (2) sealing the filled microcups by curing the sealing composition during or after it phase separates and forms a supernatant layer above the electrophoretic composition.

70. The process of claim 36 wherein step (d) is accomplished by (1) overcoating onto the electrophoretic composition with the sealing composition, and (2) curing said sealing composition.

38. A process for the manufacture of an electrophoretic display having isolated cells formed from microcups having well defined size, shape and aspect ratio, said process comprises

a) forming a layer by coating a radiation curable material over a substrate comprising common electrodes and in-plane electrode;

b) forming microcups on the radiation curable material by microembossing or imagewise exposure to radiation, whereby each of said microcups is on the substrate comprising one common electrode and an in-plane electrode;

c) filling the microcups with an electrophoretic composition;

d) sealing the microcups with a sealing composition having a specific gravity lower than that of the electrophoretic composition; and

e) laminating the sealed microcups with a transparent insulator substrate.

39. The process for the manufacture of an electrophoretic display of claim 38 wherein said transparent insulator substrate is coated with an adhesive.

41. The process of claim 38 wherein the microcups have a top opening ranging from about 10² to about 1×

10⁶ μ

m².

46. The process of claim 38 wherein said transparent insulator substrate is colorless.

47. The process of claim 46 wherein said cells have a background of the same color and are filled with an electrophoretic composition comprising charged particles of the same color dispersed in a clear colorless dielectric solvent.

48. The process of claim 46 wherein said cells have background of different colors and are filled with an electrophoretic composition comprising charged particles of the same color dispersed in a clear colorless dielectric solvent.

49. The process of claim 46 wherein said cells have a background of the same color and are filled with electrophoretic compositions comprising charged particles of different colors dispersed in a clear colorless dielectric solvent.

54. The process of claim 38 wherein said transparent insulator substrate is colored.

55. The process of claim 54 wherein said cells have a background of the black color and are filled with an electrophoretic composition comprising charged particles of the white color dispersed in a clear colorless dielectric solvent.

56. The process of claim 55 wherein said cells have the transparent insulator substrate of the same color.

57. The process of claim 55 wherein said cells have the transparent insulator substrate of different colors.

71. The process of claim 38 wherein steps (c) and (d) are accomplished by (1) filling a mixture of the sealing composition and the electrophoretic composition, and (2) sealing the filled microcups by curing the sealing composition during or after it phase separates and forms a supernatant layer above the electrophoretic composition.

72. The process of claim 38 wherein step (d) is accomplished by (1) overcoating onto the electrophoretic composition with the sealing composition, and (2) curing said sealing composition.