Display Medium And Method Of Manufacturing Display Medium

• US 20070188442A1
• Filed: 03/24/2007
• Published: 08/16/2007
• Est. Priority Date: 09/30/2004
• Status: Active Grant

• Current Assignee: Brother Kogyo Kabushiki Kaisha
• Original Assignee: Brother Kogyo Kabushiki Kaisha
• Inventors: Hattori, Yasuhiro, Enomoto, Hiroyuki
• Granted Patent: US 7,706,051 B2
• Time in Patent Office: Days
• US Class Current: 345/107
• CPC Class Codes: G02F 1/133305 Flexible substrates, e.g. plastics, organic film
• CPC Class Codes: G02F 1/133377 Cells with plural compartments or having plurality of liquid crystal microcells partitioned by walls, e.g. one microcell per pixel
• 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 1/1681 having two or more microcells partitioned by walls, e.g. of microcup type
• CPC Class Codes: G02F 2001/1678 characterised by the composition or particle type

Abstract

A display medium includes a pair of substrates, an electrophoretic medium, and a partitioning medium. The pair of substrates is disposed in spaced-apart relation and substantially parallel to each other. The electrophoretic medium is disposed between the pair of substrates and contains charged particles. An electric field generated between the pair of substrates causes the charged particles contained in the electrophoretic medium to migrate for switching a display state. The partitioning medium has fluidity and is phase-separated from the electrophoretic medium at least at room temperature. The partitioning medium is in a phase-separated state phase-separated from the electrophoretic medium. The partitioning medium is disposed between the pair of substrates as a partition to partition the electrophoretic medium.

Claims

1. A display medium comprising:

a pair of substrates disposed in spaced-apart relation and substantially parallel to each other; and

an electrophoretic medium disposed between the pair of substrates and containing charged particles, whereby an electric field generated between the pair of substrates causes the charged particles contained in the electrophoretic medium to migrate for switching a display state;

characterized in that the display medium further comprises a partitioning medium having fluidity and phase-separated from the electrophoretic medium at least at room temperature, the partitioning medium being in a phase-separated state phase-separated from the electrophoretic medium, wherein the partitioning medium is disposed between the pair of substrates as a partition to partition the electrophoretic medium.

2. The display medium according to claim 1, further comprising:

a first surface treatment part having a greater affinity to the electrophoretic medium than the partitioning medium; and

a second surface treatment part having a greater affinity to the partitioning medium than the electrophoretic medium;

wherein the second surface treatment part is disposed on a surface of at least one of the pair of substrates in a position to which the partitioning medium contacts, in accordance with a shape of the partitioning medium, and the first surface treatment part is disposed on a surface of at least one of the pair of substrates in a position at which the electrophoretic medium is to be disposed.

3. The display medium according to claim 2, wherein the first surface treatment part and the second surface treatment part are transparent and are provided on the substrate that a user views as a display.

4. The display medium according to claim 1, wherein both the electrophoretic medium and the partitioning medium are solvents insoluble to each other, or solutions containing the solvent insoluble to each other.

5. The display medium according to claim 4, wherein one of the electrophoretic medium and the partitioning medium is water or an aqueous solution, while the other is a water insoluble solvent or a solution containing the water insoluble solvent.

6. The display medium according to claim 4, wherein the partitioning medium is water or an aqueous solution, and the electrophoretic medium is a water insoluble solvent or a solution containing the water insoluble solvent.

7. The display medium according to claim 4, wherein the water insoluble solvent is an aromatic hydrocarbon solvent, an aliphatic hydrocarbon solvent, a halogenated hydrocarbon solvent, a silicone oil, or a high-purity oil, or is a mixture including two or more thereof.

8. The display medium according to claim 1, wherein the partitioning medium is colorless or white in color.

9. The display medium according to claim 1, wherein the charged particle has a surface that has a greater affinity to the electrophoretic medium than the partitioning medium.

10. The display medium according to claim 1, further comprising:

a pair of electrodes disposed on opposing surfaces of the pair of substrates respectively; and

a protective film having a resistance to fluids and provided on the opposing surface of each electrode.

11. The display medium according to claim 10, wherein the protective film has a fluorine-containing compound.

12. The display medium according to claim 1, wherein the pair of substrates are both flexible.

13. The display medium according to claim 1, further comprising spacer particles disposed between the pair of substrates to maintain a prescribed distance between the pair of substrates.

14. The display medium according to claim 13, wherein the spacer particle has a surface that has a greater affinity to the partitioning medium than the electrophoretic medium.

15. The display medium according to claim 1, further comprising an aggregated fixed partition disposed between the pair of substrates and fixed to at least one of the pair of substrates.

16. The display medium according to claim 15, wherein the fixed partition is fixed to one of the pair of substrates and separated from the other substrate.

17. The display medium according to claim 16, wherein the partitioning medium is disposed between the fixed partition and the substrate separated from the fixed partition.

18. The display medium according to claim 16, wherein a surface of the fixed partition facing the substrate from which the fixed partition is separated or a surface of the substrate separated from the fixed partition has a greater affinity to the partitioning medium than the electrophoretic medium.

19. A display medium comprising:

a pair of substrates disposed in spaced-apart relation and substantially parallel to each other;

charged particles; and

an electrophoretic medium disposed between the pair of substrates and containing the charged particles, whereby an electric field generated between the pair of substrates causes the charged particles contained in the electrophoretic medium to migrate for switching a display state;

wherein the electrophoretic medium comprises a first medium that takes on a first color and a second medium that takes on a second color, the second medium being capable of being phase-separated from the first medium at least at room temperature, the second medium and the first medium that are phase-separated from each other forming a prescribed pattern.

20. The display medium according to claim 19, further comprising:

a first surface treatment part having a greater affinity to the first medium than the second medium; and

a second surface treatment part having a greater affinity to the second medium than the first medium;

wherein the first surface treatment part and the second surface treatment part are both disposed on a surface of at least one of the pair of substrate that contacts the electrophoretic medium in accordance with the prescribed pattern.

21. The display medium according to claim 19, wherein the first medium and the second medium are solvents insoluble to each other, or solutions containing the solvent insoluble to each other.

22. The display medium according to claim 21, wherein one of the first medium and the second medium is water or an aqueous solution, while the other is a water insoluble solvent or a solution containing the water insoluble solvent.

23. The display medium according to claim 22, wherein the water is distilled water or deionized water.

24. The display medium according to claim 22, wherein the water insoluble solvent is an aromatic hydrocarbon solvent, an aliphatic hydrocarbon solvent, a halogenated hydrocarbon solvent, a silicone oil, or a high-purity oil, or is a mixture including two or more thereof.

25. The display medium according to claim 19, wherein the charged particle includes a first particle having a surface that has greater affinity to the first medium than the second medium, and a second particle having a surface that has a greater affinity to the second medium than the first medium.

26. The display medium according to claim 25, wherein the first particle and the second particle are given different colors.

27. The display medium according to claim 19, wherein the first medium and the second medium are given different colors.

28. The display medium according to claim 19, further comprising:

a pair of electrodes disposed on opposing surfaces of the pair of substrates respectively; and

a protective film having a resistance to fluids and provided on the opposing surface of each electrode.

29. The display medium according to claim 28, wherein the protective film has a fluorine-containing compound.

30. The display medium according to claim 19, wherein the pair of substrates are both flexible.

31. The display medium according to claim 19, further comprising a spacer disposed between the pair of substrates to maintain a prescribed distance between the pair of substrates.

32. The display medium according to claim 19, wherein one of the pair of electrodes comprises a first electrode and a second electrode alternately disposed in spaced-apart relation,

wherein the first medium is disposed at a position corresponding to a position of the first electrode and the second medium is disposed at a position corresponding to a position of the second electrode to form the prescribed pattern.

33. The display medium according to claim 32, further comprising:

a first surface treatment-part having a greater affinity to the first medium than the second medium; and

a second surface treatment part having a greater affinity to the second medium than the first medium;

wherein the first surface treatment part is disposed on a surfaces of the first electrode, and the second surface treatment part is disposed on a surfaces of the second electrode.

34. An electrophoretic display device comprising:

a display medium according to claim 32;

and

an electric field controlling unit that independently controls an electric field generated between the first electrode and an electrode opposing the first electrode and an electric field generated between the second electrode and an electrode opposing the second electrode.

35. The electrophoretic display device according to claim 34, wherein the electric field controlling unit independently controls the electric fields by applying voltages with different drive waveforms to the first electrode or the second electrode.

36. A method of manufacturing a display medium including a pair of substrates disposed in spaced-apart relation and substantially parallel to each other, and an electrophoretic medium disposed between the pair of substrates and containing charged particles, whereby an electric field generated between the pair of substrates causes the charged particles contained in the electrophoretic medium to migrate for switching a display state;

the manufacturing method comprising;

a medium layout step for disposing a mixture of the electrophoretic medium, and a partitioning medium having fluidity and phase-separated from the electrophoretic medium at least at room temperature, on a surface of at least one of the pair of substrates opposing the other substrate; and

a partition forming step for disposing the partitioning medium as a partition to partition the electrophoretic medium by phase-separating the electrophoretic medium and the partitioning medium in the mixture disposed on the surface of at least one of the pair of substrates in the medium layout step.

37. The method of manufacturing a display medium according to claim 36, further comprising a surface treatment step for providing a first surface treatment part having a greater affinity to the electrophoretic medium than the partitioning medium on a surface of at least one of the pair of substrates opposing the other substrate in a position at which the electrophoretic medium is to be disposed, and providing a second surface treatment part having a greater affinity to the partitioning medium than the electrophoretic medium on a surface of at least one of the pair of substrates opposing the other substrate in a position corresponding to a shape of the partitioning medium.

38. The method of manufacturing a display medium according to claim 36, wherein the charged particle has a greater affinity to the electrophoretic medium than the partitioning medium.

39. The method of manufacturing a display medium according to claim 37, further comprising a protective film forming step for forming a protective film having resistance to fluids on surfaces of the pair of electrodes disposed on opposing surfaces of the pair of substrates respectively by coating the surfaces of the pair of electrodes with a liquid including a fluorine-containing compound prior to treating the surfaces of the substrate in the surface treatment step.

40. A method of manufacturing a display medium including a pair of substrates disposed in spaced-apart relation and substantially parallel to each other, charged particles, and an electrophoretic medium disposed between the pair of substrates and containing the charged particles, whereby an electric field generated between the pair of substrates causes the charged particles contained in the electrophoretic medium to migrate for switching a display state;

the manufacturing method comprising;

a medium layout step for disposing the electrophoretic medium including a mixture of a first medium taking on a first color and a second medium taking on a second color on a surface of at least one of the pair of substrates opposing the other substrate, the second medium being capable of being phase-separated from the first medium at least at room temperature; and

a medium separation step for forming a prescribed pattern with the first medium and the second medium by phase-separating the first medium and the second medium in the electrophoretic medium disposed in the medium layout step.

41. The method of manufacturing a display medium according to claim 40, wherein one of the pair of electrodes disposed on opposing surfaces of the pair of substrates respectively includes a first electrode and a second electrode alternately disposed in spaced-apart relation;

the manufacturing method further comprising a surface treatment step for providing a first surface treatment part having a greater affinity to the first medium than the second medium on a surface of the first electrode and providing a second surface treatment part having a greater affinity to the second medium than the first medium on a surface of the second electrode;

wherein the medium separation step forms the prescribed pattern by selectively disposing the electrophoretic medium so that the first medium is disposed at a position corresponding to the first electrode and the second medium is disposed at a position corresponding to the second electrode when the first medium and the second medium are phase-separated.

42. The method of manufacturing a display medium according to claim 41, further comprising a protective film forming step for forming the protective film having a resistance to fluids on surfaces of the pair of electrodes by coating the surfaces of the pair of electrodes with a liquid including a fluorine-containing compound prior to treating the surfaces of the first electrode and the second electrode in the surface treatment step.

43. The method of manufacturing a display medium according to claim 40, wherein the charged particles comprise a first particle having a greater affinity to the first medium than the second medium, and a second particle having a greater affinity to the second medium than the first medium.