MATERIALS FOR USE IN ELECTROPHORETIC DISPLAYS

• US 20090109519A1
• Filed: 03/06/2008
• Published: 04/30/2009
• Est. Priority Date: 03/06/2007
• Status: Active Grant

• Current Assignee: E Ink Holdings Incorporated
• Original Assignee: E Ink Holdings Incorporated
• Inventors: Zalesky, Anthony, Paolini, Richard J. Jr., Herb, Craig A., Harris, George G., Honeyman, Charles Howie, Wu, Bin, Dudek, Stephen P.
• Granted Patent: US 7,826,129 B2
• Time in Patent Office: Days
• US Class Current: 359/296
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G02F 1/16756 Insulating layers
• CPC Class Codes: G02F 2001/1678 characterised by the composition or particle type

Abstract

An electrophoretic medium comprises an electrophoretic layer, a layer of lamination adhesive and a polymeric layer disposed between the electrophoretic layer and the lamination adhesive layer, the polymeric layer being impermeable to the fluid. A second form of electrophoretic medium has a layer of a complex of an alkali metal and a polymer in contact with the electrophoretic layer. A third form of electrophoretic medium comprises a plurality of discrete droplets of internal phase in a binder, and further comprises a salt.

Claims

1. An electrophoretic medium comprising:

an electrophoretic layer comprising a plurality of discrete droplets of an internal phase in a binder, the internal phase comprising plurality of particles disposed in a fluid, the particles being capable of moving through the fluid upon application of an electric field to the medium;

a layer of a lamination adhesive; and

a polymeric layer disposed between the electrophoretic layer and the lamination adhesive layer, the polymeric layer being substantially impermeable to the fluid.

2. An electrophoretic medium according to claim 1 wherein the electrophoretic layer is of the capsule-based type, with each of the droplets of internal phase being surrounded by a capsule wall, which is in turn surrounded by the binder.

3. An electrophoretic medium according to claim 1 wherein the electrophoretic layer is of the polymer-dispersed type, with the droplets of internal phase being in direct contact with the binder.

4. An electrophoretic medium according to claim 1 wherein the electrophoretic layer is of the microcell type with the droplets confined within cavities formed in a polymeric binder medium, which forms the walls of the microcells.

5. An electrophoretic medium according to claim 1 wherein the fluid is gaseous.

6. An electrophoretic medium according to claim 1 wherein the polymeric layer comprises a mixture of hard and soft domains.

7. An electrophoretic medium according to claim 1 wherein the polymeric layer comprises a water-soluble polymer.

8. An electrophoretic medium according to claim 7 wherein the polymeric layer comprises any one or more of polyethylene oxide, polyethylene glycol, polypropylene oxide, poly(ethylene oxide-co-propylene oxide), poly(ethylene glycol-co-vinyl alcohol), poly(ethylene glycol-co-vinyl acetate), poly(ethylene glycol-co-acrylic acid), poly(ethylene glycol-co-acrylamide), poly(ethylene glycol-co-vinyl pyrrolidone), poly(ethylene glycol-co-methacrylic acid), and poly(ethylene glycol-co-hydroxyethyl methacrylate).

9. An electrophoretic medium according to claim 7 wherein the water-soluble polymer has a molecular weight in the range of from about 1,000 to 10,000,000.

10. An electrophoretic medium according to claim 9 wherein the water-soluble polymer has a molecular weight in the range of from about 10,000 to 1,000,000.

32. An electrophoretic display comprising an electrophoretic medium according to claim 1 and at least one electrode arranged to apply an electric field to the electrophoretic medium.

35. A front plane laminate comprising in order:

a light-transmissive electrically-conductive layer;

a layer of a solid electrophoretic medium in electrical contact with the electrically-conductive layer;

an adhesive layer; and

a release sheet, wherein the electrophoretic medium and adhesive layer comprise a medium according to claim 1.

38. A double release film comprising:

a layer of a solid electrophoretic medium comprising a binder and having first and second surfaces on opposed sides thereof;

a first adhesive layer on the first surface of the layer of electro-optic medium;

a release sheet disposed on the opposed side of the first adhesive layer from the layer of electro-optic medium; and

a second adhesive layer on the second surface of the layer of electro-optic medium,

wherein the electrophoretic medium and adhesive layer comprise a medium according to claim 1.

41. An inverted front plane laminate for use in forming an electrophoretic display, the article of manufacture comprising, in order:

at least one of a light-transmissive protective layer and a light-transmissive electrically-conductive layer;

an adhesive layer;

a layer of a solid electrophoretic medium comprising a binder; and

a release sheet,

wherein the layer of electrophoretic medium and the adhesive layer comprise an electrophoretic medium according to claim 1.

45. An electronic book reader, portable computer, tablet computer, cellular telephone, smart card, sign, watch, shelf label or flash drive comprising a display according to claim 32.

11. A polymer-dispersed electrophoretic medium comprising:

an electrophoretic layer comprising a plurality of discrete droplets of an internal phase in a binder, the internal phase comprising plurality of particles disposed in a fluid, the particles being capable of moving through the fluid upon application of an electric field to the medium; and

a layer of a complex of an alkali metal and a polymer in contact with the electrophoretic layer.

12. An electrophoretic medium according to claim 11 wherein the electrophoretic layer is of the capsule-based type, with each of the droplets of internal phase being surrounded by a capsule wall, which is in turn surrounded by the binder.

13. An electrophoretic medium according to claim 11 wherein the electrophoretic layer is of the polymer-dispersed type, with the droplets of internal phase being in direct contact with the binder.

14. An electrophoretic medium according to claim 11 wherein the electrophoretic layer is of the microcell type with the droplets confined within cavities formed in a polymeric binder medium, which forms the walls of the microcells.

15. An electrophoretic medium according to claim 11 wherein the fluid is gaseous.

16. An electrophoretic medium according to claim 11 wherein the polymeric layer comprises any one or more of poly(ethylene oxide), poly(dimethyl siloxane), polyoxymethylene, poly(oxymethylene-oxyethylene), poly[bis-(methoxyethoxyethoxy)phosphazene], poly(propylene oxide), polyoxetane, polytetrahydrofuran, and poly(1,3-dioxolane).

17. An electrophoretic medium according to claim 11 wherein the polymer has a molecular weight in the range of from about 1,000 to 10,000,000.

18. An electrophoretic medium according to claim 17 wherein the polymer has a molecular weight in the range of from about 10,000 to 1,000,000.

19. An electrophoretic medium according to claim 11 wherein the alkali metal is lithium.

20. An electrophoretic medium according to claim 19 wherein the complex is a complex of poly(ethylene oxide) and lithium.

21. An electrophoretic medium according to claim 19 wherein the molar ratio of poly(ethylene oxide) to lithium is in the range of from about 2 to about 10.

33. An electrophoretic display comprising an electrophoretic medium according to claim 11 and at least one electrode arranged to apply an electric field to the electrophoretic medium.

36. A front plane laminate comprising in order:

a light-transmissive electrically-conductive layer;

a layer of a solid electrophoretic medium in electrical contact with the electrically-conductive layer;

an adhesive layer; and

a release sheet, wherein the electrophoretic medium comprises a medium according to claim 11.

39. A double release film comprising:

a layer of a solid electrophoretic medium comprising a binder and having first and second surfaces on opposed sides thereof;

a first adhesive layer on the first surface of the layer of electro-optic medium;

a release sheet disposed on the opposed side of the first adhesive layer from the layer of electro-optic medium; and

a second adhesive layer on the second surface of the layer of electro-optic medium,

wherein the electrophoretic medium comprises a medium according to claim 11.

42. An inverted front plane laminate for use in forming an electrophoretic display, the article of manufacture comprising, in order:

at least one of a light-transmissive protective layer and a light-transmissive electrically-conductive layer;

an adhesive layer;

a layer of a solid electrophoretic medium comprising a binder; and

a release sheet,

wherein the electrophoretic medium comprises an electrophoretic medium according to claim 11.

46. An electronic book reader, portable computer, tablet computer, cellular telephone, smart card, sign, watch, shelf label or flash drive comprising a display according to claim 33.

22. A polymer-dispersed electrophoretic medium comprising a plurality of discrete droplets of an internal phase in a binder, the internal phase comprising plurality of particles disposed in a fluid, the particles being capable of moving through the fluid upon application of an electric field to the medium, the polymer-dispersed electrophoretic medium further comprising a salt.

23. An electrophoretic medium according to claim 22 wherein the electrophoretic layer is of the capsule-based type, with each of the droplets of internal phase being surrounded by a capsule wall, which is in turn surrounded by the binder.

24. An electrophoretic medium according to claim 22 wherein the electrophoretic layer is of the polymer-dispersed type, with the droplets of internal phase being in direct contact with the binder.

25. An electrophoretic medium according to claim 22 wherein the electrophoretic layer is of the microcell type with the droplets confined within cavities formed in a polymeric binder medium, which forms the walls of the microcells.

26. An electrophoretic medium according to claim 22 wherein the fluid is gaseous.

27. An electrophoretic medium according to claim 22 wherein the salt is a tetraalkylammonium salt.

29. An electrophoretic medium according to claim 22 wherein the salt is added to the binder in the form of solid crystals having an average diameter not greater than about 5 μ

m.

30. An electrophoretic medium according to claim 29 wherein the salt is added to the binder in an amount of from about 5 to about 500 μ

mole per kilogram of binder, measured on a solids basis.

31. An electrophoretic medium according to claim 22 wherein the binder comprises poly(vinyl alcohol), polyvinylpyrrolidone, and gelatin.

34. An electrophoretic display comprising an electrophoretic medium according to claim 22 and at least one electrode arranged to apply an electric field to the electrophoretic medium.

37. A front plane laminate comprising in order:

a light-transmissive electrically-conductive layer;

a layer of a solid electrophoretic medium in electrical contact with the electrically-conductive layer;

an adhesive layer; and

a release sheet, wherein the electrophoretic medium comprises a medium according to claim 22.

40. A double release film comprising:

a layer of a solid electrophoretic medium comprising a binder and having first and second surfaces on opposed sides thereof;

a first adhesive layer on the first surface of the layer of electro-optic medium;

a release sheet disposed on the opposed side of the first adhesive layer from the layer of electro-optic medium; and

a second adhesive layer on the second surface of the layer of electro-optic medium,

wherein the electrophoretic medium comprises a medium according to claim 22.

43. An inverted front plane laminate for use in forming an electrophoretic display, the article of manufacture comprising, in order:

at least one of a light-transmissive protective layer and a light-transmissive electrically-conductive layer;

an adhesive layer;

a layer of a solid electrophoretic medium comprising a binder; and

a release sheet,

wherein the electrophoretic medium comprises an electrophoretic medium according to claim 22.

47. An electronic book reader, portable computer, tablet computer, cellular telephone, smart card, sign, watch, shelf label or flash drive comprising a display according to claim 34.

28. An electrophoretic medium according to claim 28 wherein the salt is tetrabutylammonium hexafluorophosphate.