Electrophoretic display and novel process for its manufacture

• US 6,831,770 B2
• Filed: 03/06/2002
• Issued: 12/14/2004
• Est. Priority Date: 03/03/2000
• Status: Expired due to Term

• Current Assignee: E Ink California, LLC (E Ink Corporation)
• Original Assignee: SiPix Imaging, Inc. (E Ink Holdings Incorporated)
• Inventors: Zang, Hongmei, Wu, Zarng-Arh George, Liang, Rong-Chang, Tseng, Scott C-J
• Primary Examiner(s): Dang, Hung Xuan
• Assistant Examiner(s): TRA, TUYEN Q
• Application Number:
  US10/092,936
• Publication Number:
  US 20030053190A1
• Time in Patent Office: 1,014 Days
• Field of Search: 359/296, 359/237, 359/238, 359/290, 345/105, 345/107, 430/32, 430/34, 430/38, 204/450, 204/600
• US Class Current: 359/296
• CPC Class Codes: B01J 13/16 Interfacial polymerisation
• CPC Class Codes: C08G 18/0866 the dispersing or dispersed phase being an aqueous medium
• CPC Class Codes: C08G 18/5015 having fluorine atoms
• CPC Class Codes: C08G 18/5039 containing amide groups
• CPC Class Codes: C08G 18/5066 having halogens in addition to nitrogen
• CPC Class Codes: C08G 18/792 formed by oligomerisation of aliphatic and/or cycloaliphatic isocyanates or isothiocyanates
• CPC Class Codes: C08G 18/8038 with compounds of C08G18/3225
• CPC Class Codes: C08G 18/8087 containing halogen atoms
• CPC Class Codes: G02F 1/161 Gaskets; Spacers; Sealing of cells; Filling or closing of cells
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G02F 1/1679 Gaskets; Spacers; Sealing of cells; Filling or closing of cells

Abstract

This invention relates to an electrophoretic display comprising cells which are filled with charged particles dispersed in a solvent and are individually sealed with a polymeric sealing layer.

Claims

1. An electrophoretic display comprising a plurality of cells, each cell:

a) being defined by side walls, the side walls having a side surface and a top surface;

b) being filled with an electrophoretic fluid comprising charged particles dispersed in a dielectric solvent or solvent mixture, with the top surface of the side walls being at least about 0.01μ

above the top surface of the electrophoretic fluid; and

c) being individually sealed with a polymeric sealing layer;

i) which is in intimate contact with and forms a contiguous film on the fluid;

ii) which is in intimate contact with the side surface of the side walls of the cell above the fluid; and

iii) which is in intimate contact with the top surface of the side walls of the cell.

2. The electrophoretic display of claim 1 wherein said polymeric sealing layer forms a contiguous film on the top of the sealed cells.

3. The electrophoretic display of claim 1 wherein said sealing layer is formed from a composition comprising a material selected from the group consisting of polyvalent acrylate or methacrylate, cyanoacrylates, polyvalent vinyl, polyvalent epoxide, polyvalent isocyanate, polyvalent allyl, and oligomers or polymers containing crosslinkable functional groups.

4. The electrophoretic display of claim 3 wherein said composition further comprises an additive selected from the group consisting of surfactants, antioxidants, initiators, catalysts, crosslinkers, thickeners, polymer binders, pigments, dyes and fillers.

5. The electrophoretic display of claim 3 wherein said filler is selected from the group consisting of silica, CaCO₃, BaSO₄, TiO₂, metal particles, metal oxides, and carbon black.

6. The electrophoretic display of claim 1 wherein the top surface of said side walls is about 0.02μ

to about 15μ

above the top surface of the electrophoretic fluid.

7. The electrophoretic display of claim 6 wherein the top surface of said side walls is about 0.1μ

to about 4μ

above the top surface of the electrophoretic fluid.

8. The electrophoretic display of claim 1 wherein the top surface of said sealing layer is at least about 0.01μ

above the top surface of said side walls.

9. The electrophoretic display of claim 8 wherein the top surface of said sealing layer is about 0.01μ

to about 50μ

above the top surface of said side walls.

10. The electrophoretic display of claim 9 wherein the top surface of said sealing layer is about 0.5μ

to about 8μ

above the top surface of said side walls.

11. The electrophoretic display of claim 1 wherein said sealing layer has a thickness in the range of from about 0.1μ

to about 50μ

as measured in the center of said cell.

12. The electrophoretic display of claim 11 wherein said sealing layer has a thickness in the range of from about 0.5μ

to about 15μ

as measured in the center of said cell.

13. The electrophoretic display of claim 12 wherein said sealing layer has a thickness in the range of from about 1μ

to about 8μ

as measured in the center of said cell.

32. The electrophoretic display of claim 1 wherein said polymeric sealing layer is formed from a sealing composition having a specific gravity lower than that of the electrophoretic fluid.

33. The electrophoretic display of claim 32 wherein said sealing composition is a UV curable composition.

34. The electrophoretic display of claim 32 wherein said sealing composition comprises a thermoplastic or thermoset precursor.

14. An electrophoretic display which comprises:

a) two electrode plates;

b) an array of cells, each cell;

i) being defined by side walls, the side walls having a side surface and a top surface;

ii) being filled with an electrophoretic fluid comprising charged particles dispersed in a dielectric solvent or solvent mixture, with the top surface of the side walls being at least about 0.01μ

above the top surface of the electrophoretic fluid; and

iii) being individually sealed with a polymeric sealing layer;

A) which is in intimate contact with and forms a contiguous film on the fluid;

B) which is in intimate contact with the side surface of the side walls of the cell above the fluid; and

C) which is in intimate contact with the top surface of the side walls of the cell.

15. The electrophoretic display of claim 14 further comprising an adhesive layer between the top of said polymeric sealing layer and one of said electrode plates.

16. The electrophoretic display of claim 15 wherein said polymeric sealing layer is formed from a composition comprising a material selected from the group consisting of polyvalent acrylate or methacrylate, cyanoacrylates, polyvalent vinyl, polyvalent epoxide, polyvalent isocyanate, polyvalent allyl, and oligomers or polymers containing crosslinkable functional groups.

17. The electrophoretic display of claim 16 wherein said composition further comprises one or more additive selected from the group consisting of surfactants, antioxidants, initiators, catalysts, crosslinkers, thickeners, polymer binders, pigments, dyes and fillers.

18. The electrophoretic display of claim 17 wherein said filler is selected from the group consisting of silica, CaCO₃, BaSO₄, TiO₂, metal particles, metal oxides, and carbon black.

19. The electrophoretic display of claim 15 wherein said adhesive layer is a pressure sensitive adhesive, a hot melt adhesive, a heat, moisture, or radiation curable adhesive.

20. The electrophoretic display of claim 19 wherein said adhesive layer is formed from a material selected from a group consisting of acrylics, styrene-butadiene copolymers, styrene-butadiene-styrene block coplymers, styrene-isoprene-styrene block copolymers, polyvinylbutyal, cellulose acetate butyrate, polyvinylpyrrolidone, polyurethanes, polyamides, ethylene-vinylacetate copolymers, epoxides, multifunctional acrylates, vinyls, vinylethers, and their oligomers, polymers, and copolymers.

21. The electrophoretic display of claim 15 wherein said sealing layer and said adhesive layer are formed from the same material.

22. The electrophoretic display of claim 21 wherein said material is a radiation curable material.

23. The electrophoretic display of claim 15 wherein said sealing layer and said adhesive layer are formed from different materials.

24. The electrophoretic display of claim 14 wherein the top surface of said side walls is about 0.02μ

to about 15μ

above the top surface of the electrophoretic fluid.

25. The electrophoretic display of claim 24 wherein the top surface of said side walls is about 0.1 μ

to about 4μ

above the top surface of the electrophoretic fluid.

26. The electrophoretic display of claim 14 wherein the top surface of said sealing layer is at least about 0.01μ

above the top surface of said side walls.

27. The electrophoretic display of claim 26 wherein the top surface of said sealing layer is about 0.01μ

to about 50μ

above the top surface of said side walls.

28. The electrophoretic display of claim 27 wherein the top surface of said sealing layer is about 0.5μ

to about 8μ

above the top surface of said side walls.

29. The electrophoretic display of claim 14 wherein said sealing layer has a thickness in the range of from about 0.1μ

to about 50μ

as measured in the center of said cell.

30. The electrophoretic display of claim 29 wherein said sealing layer has a thickness in the range of from about 0.5μ

to about 15μ

as measured in the center of said cell.

31. The electrophoretic display of claim 30 wherein said sealing layer has a thickness in the range of from about 1μ

to about 8μ

as measured in the center of said cell.

35. The electrophoretic display of claim 14 wherein said polymeric sealing layer is formed from a sealing composition having a specific gravity lower than that of the electrophoretic fluid.

36. The electrophoretic display of claim 35 wherein said sealing composition is a UV curable composition.

37. The electrophoretic display of claim 35 wherein said sealing composition comprises a thermoplastic or thermoset precursor.