ELECTROPHORETIC DISPLAY SHEET, ELECTROPHORETIC DISPLAY, METHOD FOR PRODUCING ELECTROPHORETIC DISPLAY, AND ELECTRONIC APPARATUS

• US 20080204855A1
• Filed: 02/20/2008
• Published: 08/28/2008
• Est. Priority Date: 02/23/2007
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: YAMAMOTO, Hitoshi
• Granted Patent: US 7,804,638 B2
• Time in Patent Office: Days
• US Class Current: 359/296
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G02F 1/16757 Microcapsules
• CPC Class Codes: G02F 2001/1678 characterised by the composition or particle type

Abstract

An electrophoretic display sheet includes: a substrate; at least one kind of electrophoretic particles; an electrophoretic dispersion liquid containing the at least one kind of electrophoretic particles; a microcapsule having a shell for enclosing the electrophoretic dispersion liquid therein; a microcapsule-containing layer provided on a surface side of the substrate to contain the microcapsule; and a binder having a function of retaining the microcapsule and having viscosity under room temperature, the microcapsule-containing layer including the microcapsule and the binder; and the electrophoretic particles being contained in the electrophoretic dispersion liquid in a ratio of 30% to 60% wt. with respect to a weight of the electrophoretic dispersion liquid.

Claims

1. An electrophoretic display sheet, comprising:

a substrate having a surface side;

at least one kind of electrophoretic particles;

an electrophoretic dispersion liquid that contains the at least one kind of electrophoretic particles;

a microcapsule having a shell, the shell enclosing the electrophoretic dispersion liquid therein;

a microcapsule-containing layer provided on the surface side of the substrate, the microcapsule-containing layer containing the microcapsule; and

a binder that retains the microcapsule, the binder having viscosity at temperatures of approximately room temperature and below;

the microcapsule-containing layer including the microcapsule and the binder; and

the at least one kind of electrophoretic particles being contained in the electrophoretic dispersion liquid in a ratio of 30% to 60% by weight with respect to a weight of the electrophoretic dispersion liquid.

3. The electrophoretic display sheet according to claim 1, the electrophoretic particles including:

(i) white particles; and

(ii) color particles, the color particles having a tone different from that of the white particles;

(iii) a content ratio of the white particles being in a range from 94% to 98% wt. with respect to a weight of the electrophoretic particles; and

(iv) a content ratio of the color particles being in a range from 2% to 6% wt. with respect to the weight of the electrophoretic particles.

4. The electrophoretic display sheet according to claim 1, hydrophobic treatment being applied to surfaces of the electrophoretic particles.

5. The electrophoretic display sheet according to claim 3, the white particles being made of titanium oxide subjected to silica/alumina treatment;

and

the color particles being made of carbon black.

6. The electrophoretic display sheet according to claim 1, the binder having a melting point of 25°

C. or lower.

7. The electrophoretic display sheet according to claim 1, the binder including (metha)acrylic acid ester.

8. The electrophoretic display sheet according to claim 7, the (metha)acrylic acid ester having a total carbon number ranging from 5 to 20.

9. The electrophoretic display sheet according to claim 1, the shell including a material that contains gelatin.

10. The electrophoretic display sheet according to claim 1, the electrophoretic dispersion liquid being prepared by dispersing the electrophoretic particles in a dispersion medium that contains liquid paraffin.

11. The electrophoretic display sheet according to claim 10, the liquid paraffin being isoparaffin.

12. The electrophoretic display sheet according to claim 11, the isoparaffin having a carbon number ranging from 5 to 15.

13. An electrophoretic display, comprising:

the electrophoretic display sheet according to claim 1; and

an opposing substrate, the opposing substrate being provided on a side facing the surface side of the substrate having the microcapsule-containing layer provided thereon.

14. The electrophoretic display according to claim 13, further comprising an adhesive layer for bonding between the electrophoretic display sheet and the opposing substrate.

15. The electrophoretic display according to claim 14, the adhesive layer having insulating properties.

16. The electrophoretic display according to claim 14, the adhesive layer preventing the diffusion of ions to the opposing substrate from the electrophoretic display sheet.

17. The electrophoretic display according to claim 14, the adhesive layer absorbing and retaining water entering the electrophoretic display.

18. The electrophoretic display according to claim 14, the adhesive layer reducing stress occurring upon the bonding between the electrophoretic display sheet and the opposing substrate.

19. The electrophoretic display according to claim 14, the adhesive layer being predominantly made of polyurethane.

20. The electrophoretic display according to claim 14, wherein under a condition where a mean thickness of the adhesive layer is set to A μ

m and a mean thickness of the microcapsule-containing layer is set to B μ

m, a value of A/B ranges from 0.1 to 3.

21. A method for producing an electrophoretic display according to claim 1, comprising:

bonding an opposing substrate on a side facing the surface side of the substrate with the microcapsule-containing layer being provided between the substrate and the opposing substrate, the bonding being performed at temperatures of approximately room temperature and below to move and relocate the microcapsules in the microcapsule-containing layer such that an arrangement density of the microcapsules is equalized.

22. The method for producing an electrophoretic display according to claim 21, wherein when the bonding is performed, a thickness of the microcapsule-containing layer is reduced to deform the microcapsule.

23. An electronic apparatus comprising the electrophoretic display according to claim 13.

2. An electrophoretic display sheet, comprising:

a substrate that includes a surface side;

at least one kind of electrophoretic particles;

an electrophoretic dispersion liquid that includes the at least one kind of electrophoretic particles;

a microcapsule having a shell, the shell enclosing the electrophoretic dispersion liquid therein;

a microcapsule-containing layer provided on the surface side of the substrate, the microcapsule-containing layer containing the microcapsule; and

a binder that retains the microcapsule, the binder having viscosity at temperatures of approximately room temperature and below, the microcapsule-containing layer including the microcapsule and the binder;

the binder having a 180-degree peel adhesion strength (in accordance with JIS-K-6854) ranging from 5N/25 mm to 150N/25 mm; and

the electrophoretic particles being contained in the electrophoretic dispersion liquid in a ratio of 30% to 60% by weight with respect to a weight of the electrophoretic dispersion liquid.

24. An electrophoretic display sheet, comprising:

a substrate that includes a surface side;

at least one kind of electrophoretic particles;

an electrophoretic dispersion liquid that contains the at least one kind of electrophoretic particles;

at least one microcapsule, the electrophoretic dispersion liquid being disposed within the at least one microcapsule;

a binder that retains the at least one microcapsule, the binder having viscosity at temperatures of approximately room temperature and below;

the at least one kind of electrophoretic particles being contained in the electrophoretic dispersion liquid in a ratio of 30% to 60% by weight with respect to a weight of the electrophoretic dispersion liquid.

25. The electrophoretic display sheet according to claim 24, further comprising:

an opposing substrate, the microcapsule-containing layer being disposed between the substrate and the opposing substrate.

26. The electrophoretic display sheet according to claim 25, the at least one microcapsule comprising a plurality of microcapsules in a single-layer structure, the plurality of microcapsules being arranged in parallel to one another in a vertical or a horizontal direction such that the plurality of microcapsules are not overlapping in the vertical or horizontal direction.