ELECTRO-OPTIC DISPLAY AND MATERIALS FOR USE THEREIN

• US 20070035808A1
• Filed: 07/05/2006
• Published: 02/15/2007
• Est. Priority Date: 07/09/2001
• Status: Active Grant

• Current Assignee: E Ink Holdings Incorporated
• Original Assignee: E Ink Holdings Incorporated
• Inventors: Loxley, Andrew, Crossley, Glen, Geramita, Katharine, Steiner, Michael, Zhang, Libing, Webber, Richard, Amundson, Karl, Zehner, Robert, Duthaler, Gregg, Ritter, John, Abramson, Justin, Holman, Mavyn
• Granted Patent: US 7,535,624 B2
• Time in Patent Office: Days
• US Class Current: 359/296
• CPC Class Codes: C08K 3/017 Antistatic agents
• CPC Class Codes: C08K 3/22 of metals
• CPC Class Codes: C09J 11/04 inorganic
• CPC Class Codes: C09J 2301/408 additives as essential feature of the adhesive layer
• CPC Class Codes: C09J 7/10 without carriers
• CPC Class Codes: C09J 7/38 Pressure-sensitive adhesives [PSA]
• CPC Class Codes: C09J 9/02 Electrically-conducting adhesives
• CPC Class Codes: G02B 26/026 based on the rotation of particles under the influence of an external field, e.g. gyricons, twisting ball displays based on orientable dipolar particles G02F1/172; based on electrophoresis G02F1/167
• CPC Class Codes: G02F 1/133305 Flexible substrates, e.g. plastics, organic film
• CPC Class Codes: G02F 1/133368 Cells having two substrates with different characteristics, e.g. different thickness or material
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G02F 1/16757 Microcapsules
• CPC Class Codes: G02F 1/172 based on a suspension of orientable dipolar particles, e.g. suspended particles displays
• CPC Class Codes: G02F 2202/16 conductive
• CPC Class Codes: G02F 2202/28 Adhesive materials or arrangements
• CPC Class Codes: H05K 3/323 by applying an anisotropic conductive adhesive layer over an array of pads

Abstract

An electro-optic display comprises a layer (130) of a solid electro-optic material, at least one electrode disposed adjacent the layer (130) of electro-optic material, and a layer (180) of a lamination adhesive interposed between the layer (130) of electro-optic material and the electrode, the lamination adhesive (180) having a higher electrical conductivity in a direction perpendicular to the layer of lamination adhesive than in the plane of the layer.

Claims

1. A process for forming a layer of an anisotropic adhesive having greater conductivity perpendicular to the plane of the layer than in this plane, the process comprising:

dispersing a plurality of conductive particles in an adhesive matrix, the particles having a complex conductivity differing from that of the matrix;

applying to the particles/matrix mixture an electric or magnetic field effective to cause the particles to form conductive strands extending substantially perpendicular to the plane of the layer; and

increasing the viscosity of the matrix to prevent the particles moving our of the strands.

2. A process according to claim 1 wherein the conductive particles have a conductivity greater than about 10⁻

9 S/cm. and a diameter not greater than about one-tenth of the thickness of the layer of lamination adhesive.

3. A process according to claim 1 wherein the conductive particles are formed from a semiconducting polymer.

4. A process according to claim 1 wherein the conductive particles are formed from a low conductivity material having a polar material adsorbed on its surface to increase its conductivity.

5. A process according to claim 1 wherein the matrix has a conductivity less than about 10⁻

10 S/cm.

6. A process according to claim 1 wherein the particles are magnetizable and the matrix is substantially non-magnetizable.

7. A process according to claim 6 wherein the magnetizable particles comprise an iron oxide.

8. A process according to claim 1 wherein the layer of anisotropic adhesive formed is thereafter laminated to a layer of an electro-optic material.

9. An electro-optic display comprising a layer of a solid electro-optic material, and at least one electrode arranged to apply an electric field to the layer of electro-optic material, the layer of electro-optic material comprising a binder, the binder having a volume resistivity, measured at 10°

C., which does not change by a factor of more than about 3 after being held at 25°

C. and 45 per cent relative humidity for 1000 hours.

10. An electro-optic display according to claim 9 wherein the volume resistivity of the binder measured at 10°

C. does not change by a factor of more than about 2 after being held at 25°

C. and 45 per cent relative humidity for 1000 hours.

11. An electro-optic display according to claim 10 wherein the volume resistivity of the binder measured at 10°

C. does not change by a factor of more than about 1. 5 after being held at 25°

C. and 45 per cent relative humidity for 1000 hours.

12. An electro-optic display according to claim 9 wherein the binder essentially free from plasticizer.

13. An electro-optic display according to claim 9 wherein the binder exhibits a change in the enthalpy associated with any phase transition in the material, as measured by differential scanning calorimetry, that is not more than about 2 Joules per gram after being held at 25°

C. and 45 per cent relative humidity for 1000 hours.

14. An electro-optic display according to claim 9 wherein the binder exhibits a change in dielectric constant of less than about 2 after being held at 25°

C. and 45 percent relative humidity for 1000 hours.

15. An electro-optic display according to claim 9 wherein the binder comprises a blend of at least two binder materials, at least one of which has a volume resistivity, measured at 10°

C., which changes by a factor of more than 3 after being held at 25°

C. and 45 percent relative humidity for 1000 hours.

16. An electro-optic display according to claim 9 wherein the binder comprises at least one polyurethane.

17. An electro-optic display according to claim 16 wherein the binder comprises a blend of at least two polyurethanes.

18. An electro-optic display according to claim 17 wherein the binder comprises a blend of a non-ionically stabilized polyester-based polyurethane and an anionically stabilized polyester-based polyurethane.

19. An electro-optic display according to claim 9 wherein the binder has a volume resistivity, measured at 10°

C., of not more than about 3×

10¹⁰ ohm cm.

20. An electro-optic display according to claim 9 wherein the electro-optic medium comprises a rotating bichromal member, polymer-dispersed electrophoretic or microcell electrophoretic medium.

21. An electro-optic display according to claim 9 wherein the electro-optic medium comprises an electrophoretic medium comprising a plurality of capsules, each capsule comprising a capsule wall and an internal phase encapsulated within capsule wall, the internal phase comprising electrically charged particles suspended in a fluid and capable of moving through the fluid on application of an electric field to the electrophoretic material.

22. A microcavity electrophoretic display comprising a layer of a binder having a plurality of closed cavities formed therein, said cavities being at least partially filled with an electrophoretic medium comprising a plurality of electrically charged particles in a fluid and capable of moving therethrough on application of an electric field to the electrophoretic medium, the display further comprising at least one electrode arranged to apply an electric field to the electrophoretic medium, the binder being characterized by any one or more of the following:

(a) having a volume resistivity, measured at 10°

C., which does not change by a factor of more than about 3 after being held at 25°

C. and 45 percent relative humidity for 1000 hours;

(b) having a volume resistivity which changes by a factor of less than about 10 within a range of 10 to 90 percent relative humidity and over a temperature range of 10 to 50°

C.;

(c) having a shear modulus at 120°

C. of not more than about 1 megaPascal;

(d) the product of the dielectric constant and the volume resistivity of the binder is not greater than the product of the dielectric constant and the volume resistivity of the fluid within a range of 10 to 90 percent relative humidity and over a temperature range of 10 to 50°

C.;

(e) comprising an ultra-violet stabilizer;

(f) the ratio of the dielectric constant of the binder to the dielectric constant of the fluid within the temperature over the range of from 10 to 50°

C. does not vary from this ratio at 25°

C. by more than about 2 percent;

(g) the ratio of the volume resistivity of the binder to the volume resistivity of the fluid within the temperature over the range of from 10 to 50°

C. does not vary from this ratio at 25°

C. by more than a factor of about 100;

(h) the solubility of the fluid in the binder does not exceed about 1 percent weight/weight over the range of 10 to 50°

C.; and

(i) the binder is substantially free from mobile species.

23. An electrophoretic display according to claim 22 wherein the electrophoretic medium comprises a polymer-dispersed electrophoretic or microcell electrophoretic medium.

24. An electrophoretic display according to claim 22 wherein the electrophoretic medium comprises a plurality of capsules, each capsule comprising a capsule wall and an internal phase encapsulated within the capsule wall, the internal phase comprising electrically charged particles in a fluid and capable of moving through the fluid on application of an electric field to the electrophoretic medium.

25. An article of manufacture comprising in order:

a light-transmissive electrically-conductive layer;

a layer of an electrophoretic medium in electrical contact with the electrically-conductive layer, the electrophoretic medium comprising a binder having a plurality of closed cavities formed therein, said cavities being at least partially filled with an electrophoretic medium comprising a plurality of electrically charged particles in a fluid and capable of moving therethrough on application of an electric field to the electrophoretic medium;

an adhesive layer; and

a release sheet,

the binder being characterized by any one or more of the following;

(a) having a volume resistivity, measured at 10°

C., which does not change by a factor of more than about 3 after being held at 25°

C. and 45 percent relative humidity for 1000 hours;

(b) having a volume resistivity which changes by a factor of less than about 10 within a range of 10 to 90 percent relative humidity and over a temperature range of 10 to 50°

C.;

(c) having a shear modulus at 120°

C. of not more than about 1 megaPascal;

(d) the product of the dielectric constant and the volume resistivity of the binder is not greater than the product of the dielectric constant and the volume resistivity of the fluid within a range of 10 to 90 percent relative humidity and over a temperature range of 10 to 50°

C.;

(e) comprising an ultra-violet stabilizer;

(f) the ratio of the dielectric constant of the binder to the dielectric constant of the fluid within the temperature over the range of from 10 to 50°

C. does not vary from this ratio at 25°

C. by more than about 2 percent;

(g) the ratio of the volume resistivity of the binder to the volume resistivity of the fluid within the temperature over the range of from 10 to 50C. does not vary from this ratio at 25°

C. by more than a factor of about 100;

(h) the solubility of the fluid in the binder does not exceed about 1 percent weight/weight over the range of 10 to 50°

C.; and

(i) the binder is substantially free from mobile species.

26. An article of manufacture according to claim 25 wherein the electrophoretic medium comprises a polymer-dispersed electrophoretic or microcell electrophoretic medium.

27. An article of manufacture according to claim 25 wherein the electrophoretic medium comprises a plurality of capsules, each capsule comprising a capsule wall and an internal phase encapsulated within the capsule wall, the internal phase comprising electrically charged particles in a fluid and capable of moving through the fluid on application of an electric field to the electrophoretic medium.

28. An article of manufacture comprising:

a layer of an electrophoretic medium having first and second surfaces on opposed sides thereof, the electrophoretic medium comprising a binder having a plurality of closed cavities formed therein, said cavities being at least partially filled with an internal comprising a plurality of electrically charged particles in a fluid and capable of moving therethrough on application of an electric field to the electrophoretic medium;

a first adhesive layer on the first surface of the layer of electrophoretic medium;

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

a second adhesive layer on the second surface of the layer of electrophoretic medium,

the binder being characterized by any one or more of the following;

(a) having a volume resistivity, measured at 10°

C., which does not change by a factor of more than about 3 after being held at 25°

C. and 45 percent relative humidity for 1000 hours;

(b) having a volume resistivity which changes by a factor of less than about 10 within a range of 10 to 90 percent relative humidity and over a temperature range of 10 to 50°

C.;

(c) having a shear modulus at 120°

C. of not more than about 1 megaPascal;

(d) the product of the dielectric constant and the volume resistivity of the binder is not greater than the product of the dielectric constant and the volume resistivity of the fluid within a range of 10 to 90 percent relative humidity and over a temperature range of 10 to 50°

C.;

(e) comprising an ultra-violet stabilizer;

(f) the ratio of the dielectric constant of the binder to the dielectric constant of the fluid within the temperature over the range of from 10 to 50°

C. does not vary from this ratio at 25°

C. by more than about 2 percent;

(g) the ratio of the volume resistivity of the binder to the volume resistivity of the fluid within the temperature over the range of from 10 to 50°

C. does not vary from this ratio at 25°

C. by more than a factor of about 100;

(h) the solubility of the fluid in the binder does not exceed about 1 percent weight/weight over the range of 10 to 50°

C.; and

(i) the binder is substantially free from mobile species.

29. An article of manufacture according to claim 28 wherein the electrophoretic medium comprises a polymer-dispersed electrophoretic or microcell electrophoretic medium.

30. An article of manufacture according to claim 28 wherein the electrophoretic medium comprises an electrophoretic medium comprising a plurality of capsules, each capsule comprising a capsule wall and an internal phase encapsulated within the capsule wall, the internal phase comprising electrically charged particles in a fluid and capable of moving through the fluid on application of an electric field to the electrophoretic medium.

31. An article of manufacture comprising in order:

a light-transmissive electrically-conductive layer;

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

an adhesive layer; and

a release sheet,

the adhesive layer being characterized by any one or more of the following;

(a) having a volume resistivity, measured at 10°

C., which does not change by a factor of more than about 3 after being held at 25°

C. and 45 percent relative humidity for 1000 hours;

(b) the volume resistivity of the adhesive changes by a factor of less than about 10 within a range of 10 to 90 percent relative humidity and over a temperature range of 10 to 50°

C.;

(c) the adhesive has a shear modulus at 120°

C. of not more than about 1 megaPascal;

(d) the product of the dielectric constant and the volume resistivity of the adhesive is not greater than the product of the dielectric constant and the volume resistivity of the electro-optic medium within a range of 10 to 90 percent relative humidity and over a temperature range of 10 to 50°

C.;

(e) comprising an ultra-violet stabilizer;

(f) being substantially free from mobile species.

32. An article of manufacture according to claim 31 wherein the electro-optic medium comprises a rotating bichromal member, polymer-dispersed electrophoretic or microcell electrophoretic medium.

33. An article of manufacture according to claim 31 wherein the electro-optic medium comprises an electrophoretic medium comprising a plurality of capsules, each capsule comprising a capsule wall and an internal phase encapsulated within the capsule wall, the internal phase comprising electrically charged particles suspended in a fluid and capable of moving through the fluid on application of an electric field to the electrophoretic material.

34. An article of manufacture comprising in order:

a light-transmissive electrically-conductive layer;

a layer of an electrophoretic medium in electrical contact with the electrically-conductive layer, the electrophoretic medium comprising a plurality of electrically charged particles in a fluid and capable of moving therethrough on application of an electric field to the electrophoretic medium;

an adhesive layer; and

a release sheet,

the adhesive layer being characterized by any one or more of the following;

(a) the product of the dielectric constant and the volume resistivity of the adhesive layer is not greater than the product of the dielectric constant and the volume resistivity of the fluid within a range of 10 to 90 percent relative humidity and over a temperature range of 10 to 50°

C.;

(b) the ratio of the dielectric constant of the adhesive layer to the dielectric constant of the fluid within the temperature over the range of from 10 to 50°

C. does not vary from this ratio at 25°

C. by more than about 2 percent;

(c) the ratio of the volume resistivity of the adhesive layer to the volume resistivity of the fluid within the temperature over the range of from 10 to 50°

C. does not vary from this ratio at 25°

C. by more than a factor of about 100; and

(d) the solubility of the fluid in the adhesive layer does not exceed about 1 percent weight/weight over the range of 10 to 50°

C.

35. An article of manufacture according to claim 34 wherein the electrophoretic medium comprises a polymer-dispersed electrophoretic or microcell electrophoretic medium.

36. An article of manufacture according to claim 34 wherein the electrophoretic medium comprises a plurality of capsules, each capsule comprising a capsule wall and an internal phase encapsulated within the capsule wall, the internal phase comprising electrically charged particles in a fluid and capable of moving through the fluid on application of an electric field to the electrophoretic material.

37. An article of manufacture comprising:

a layer of a solid electro-optic medium having first and second surfaces on opposed sides thereof,

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

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

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

at least one of first and second adhesive layers being characterized by any one or more of the following;

(a) having a volume resistivity, measured at 10°

C., which does not change by a factor of more than about 3 after being held at 25°

C. and 45 percent relative humidity for 1000 hours;

(b) the volume resistivity of the adhesive changes by a factor of less than about 10 within a range of 10 to 90 percent relative humidity and over a temperature range of 10 to 50°

C.;

(c) the adhesive has a shear modulus at 120°

C. of not more than about 1 megaPascal;

(d) the product of the dielectric constant and the volume resistivity of the adhesive is not greater than the product of the dielectric constant and the volume resistivity of the electro-optic medium within a range of 10 to 90 percent relative humidity and over a temperature range of 10 to 50°

C.;

(e) comprising an ultra-violet stabilizer; and

(f) being substantially free from mobile species.

38. An article of manufacture according to claim 37 wherein the electro-optic medium comprises a rotating bichromal member, polymer-dispersed electrophoretic or microcell electrophoretic medium.

39. An article of manufacture according to claim 37 wherein the electro-optic medium comprises an electrophoretic medium comprising a plurality of capsules, each capsule comprising a capsule wall and an internal phase encapsulated within the capsule wall, the internal phase comprising electrically charged particles in a fluid and capable of moving through the fluid on application of an electric field to the electrophoretic medium.

40. An article of manufacture comprising:

a layer of an electrophoretic medium having first and second surfaces on opposed sides thereof, the electrophoretic medium comprising a plurality of electrically charged particles in a fluid and capable of moving therethrough on application of an electric field to the electrophoretic medium;

a first adhesive layer on the first surface of the layer of electrophoretic medium;

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

a second adhesive layer on the second surface of the layer of electrophoretic medium,

at least one of first and second adhesive layers being characterized by any one or more of the following;

(a) the product of the dielectric constant and the volume resistivity of the adhesive layer is not greater than the product of the dielectric constant and the volume resistivity of the fluid within a range of 10 to 90 percent relative humidity and over a temperature range of 10 to 50°

C.;

(b) the ratio of the dielectric constant of the adhesive layer to the dielectric constant of the fluid within the temperature over the range of from 10 to 50°

C. does not vary from this ratio at 25°

C. by more than about 2 percent;

(c) the ratio of the volume resistivity of the adhesive layer to the volume resistivity of the fluid within the temperature over the range of from 10 to 50°

C. does not vary from this ratio at 25°

C. by more than a factor of about 100; and

(d) the solubility of the fluid in the adhesive layer does not exceed about 1 percent weight/weight over the range of 10 to 50°

C.

41. An article of manufacture according to claim 40 wherein the electrophoretic medium comprises a polymer-dispersed electrophoretic or microcell electrophoretic medium.

42. An article of manufacture according to claim 42 wherein the electrophoretic medium comprises a plurality of capsules, each capsule comprising a capsule wall and an internal phase encapsulated within the capsule wall, the internal phase comprising electrically charged particles in a fluid and capable of moving through the fluid on application of an electric field to the electrophoretic medium.