Shutter mode microencapsulated electrophoretic display

• US 6,130,774 A
• Filed: 04/27/1999
• Issued: 10/10/2000
• Est. Priority Date: 04/27/1998
• Status: Expired due to Term

• Current Assignee: E Ink Corporation (E Ink Holdings Incorporated)
• Original Assignee: E Ink Corporation (E Ink Holdings Incorporated)
• Inventors: Albert, Jonathan D., Comiskey, Barrett
• Primary Examiner(s): Sugarman, Scott J.
• Assistant Examiner(s): Spector, David N.
• Application Number:
  US09/300,585
• Time in Patent Office: 532 Days
• Field of Search: 359/296, 359/263, 359/277, 252/583, 264/4, 345/107, 349/86, 430/32, 430/34, 430/35
• US Class Current: 359/296
• CPC Class Codes: B41J 3/4076 printing on rewritable, bistable "electronic paper" by a focused electric or magnetic field
• 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 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/1345 Conductors connecting electrodes to cell terminals
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G02F 1/16757 Microcapsules
• CPC Class Codes: G02F 2202/28 Adhesive materials or arrangements
• CPC Class Codes: G09F 9/302 characterised by the form or geometrical disposition of the individual elements
• CPC Class Codes: G09F 9/372 the positions of the elements being controlled by the application of an electric field
• CPC Class Codes: H10K 10/462 Insulated gate field-effect transistors [IGFETs]
• CPC Class Codes: H10K 85/30 Coordination compounds
• CPC Class Codes: H10K 85/60 Organic compounds having low molecular weight H10K85/10 - H10K85/50 take precedence

Abstract

An electrophoretic display element includes a capsule having a first, larger surface and a second, smaller surface. The capsule contains a suspending fluid and at least one particle dispersed within said suspending fluid. Application of a first electrical field causes the particle or particles to migrate towards the first, larger surface of the capsule, causing it to take on the visual appearance of the particles. Application of a second electrical field causes the particle or particles to migrate towards the second, smaller surface, allowing the capsule to take on the visual appearance of the dispersing fluid or of a substrate or electrode positioned behind the display element. Displays may be fabricated from multiple display elements arranged on a substrate.

Claims

1. An electrophoretic display element comprising:

a capsule having a first surface and a second surface, said first surface having a larger projected surface area than a projected surface area of said second surface when both surfaces are viewed in an intended viewing direction, said capsule containing;

a suspending fluid; and

at least one particle dispersed within said suspending fluid;

wherein application of a first electrical field causes the at least one particle to migrate towards said first surface and application of a second electrical field causes the at least one particle to migrate towards said second surface, the at least one particle having an optical property such that said display element is substantially reflective when the at least one particle migrates towards said first surface.

2. An electrophoretic display comprising:

a plurality of display elements, each display element including;

a capsule having a first surface and a second surface, said first surface having a larger projected surface area than a projected surface area of said second surface when both surfaces are viewed in an intended viewing direction, said capsule containing;

a suspending fluid; and

at least one particle dispersed within said suspending fluid; and

a first substrate defining a plurality of cavities, each cavity adapted to receive at least one of said plurality of display elements therein.

3. The display of claim 2 further comprising a second substrate disposed over said first substrate, enclosing said cavity.

4. The display of claim 2 wherein said first substrate comprises an embossed substrate defining said cavity.

5. The display of claim 2 wherein said first substrate comprises an etched substrate defining said cavity.

6. The display of claim 2 wherein said first substrate comprises a micromachined substrate defining said cavity.

7. The display of claim 2 wherein said first substrate defines conical receiving cavities.

8. The display of claim 2 wherein said first substrate defines grooves for receiving said capsule.

9. The display of claim 8 wherein said first substrate defines grooves having a triangular cross section for receiving said capsule.

10. The display of claim 8 wherein said first substrate defines grooves having a trapezoidal cross section for receiving said capsule.

11. The display of claim 8 wherein said first substrate defines grooves for receiving said capsule wherein said first surface and said second surface are disposed in a substantially parallel relationship.

12. A method of manufacturing an electrophoretic display comprising the steps of:

manufacturing a plurality of display elements, each display element being manufactured by a process comprising the steps of;

encapsulating with a capsule a suspending fluid having a first optical property, and at least one particle dispersed within said suspending fluid and having a second optical property different from said first optical property; and

shaping said capsule to produce a first surface and a second surface, said first surface having a larger projected surface area than a projected surface area of said second surface when both surfaces are viewed in an intended viewing direction;

providing a substrate defining a plurality of cavities, each cavity adapted to receive one of said plurality of display elements therein; and

situating at least one of said plurality of display elements within at least one of said plurality of cavities defined within said substrate.

13. The method of claim 12 comprising the additional step of providing electrodes adapted to address each of said display elements individually.

14. The method of claim 12 wherein the step of providing a substrate comprises providing a substrate defining a plurality of conical cavities therein.

15. The method of claim 12 wherein the step of providing a substrate comprises providing a substrate defining a plurality of pyramidal cavities therein.

16. The method of claim 12 wherein the step of providing a substrate comprises providing a substrate defining a plurality of grooves therein.

17. An electrophoretic display element comprising:

a capsule having a first surface and a second surface and containing a structural portion, said structural portion adjacent to at least a portion of said second surface of said capsule and oriented at an oblique angle relative to said second surface to create a display portion of said capsule wherein one of said first surface and said second surface has a larger projected area than the other of said first surface and said second surface, said projected areas being measured when viewed in an intended viewing direction, said display portion including;

a suspending fluid; and

at least one particle dispersed within said suspending fluid;

wherein application of a first electrical field causes the at least one particle to migrate towards said first surface of said capsule and application of a second electrical field causes the at least one particle to migrate towards said second surface of said capsule.

18. The display element of claim 17 wherein the at least one particle has an optical property such that said display element is substantially opaque when the at least one particle migrates towards said first surface.

19. The display element of claim 17 wherein the at least one particle has an optical property such that said display element is substantially reflective when the at least one particle migrates towards said first surface.

20. The display element of claim 17 wherein said display element is substantially transparent when the at least one particle migrates towards said second surface.

21. The display element of claim 17 wherein said structural portion comprises a polymer.

22. The display element of claim 17 wherein said structural portion comprises a thermoset polymer.

23. The display element of claim 17 wherein said structural portion comprises a photohardenable polymer.

24. A method of manufacturing an electrophoretic display element comprising the steps of:

encapsulating within a capsule a suspending fluid having a first optical property, at least one particle dispersed within said suspending fluid and having a second optical property different from said first optical property, and a structural material;

orienting said capsule in a predetermined orientation; and

treating said structural material within said capsule to form a capsule comprising a display portion having a first surface, a second surface and a structural portion, said structural portion adjacent to at least a portion of said second surface and oriented at an oblique angle relative to said second surface of said capsule, and one of said first surface and said second surface having a larger projected area than the other of said first surface and said second surface, said projected areas being measured when viewed in an intended viewing direction.

25. The method according to claim 24 wherein the step of treating said structural material comprises polymerizing said structural material.

26. The method according to claim 24 wherein the step of treating said structural material comprises photohardening said structural material.

27. The method according to claim 24 wherein the step of treating said structural material comprises thermally treating said structural material.

28. The method according to claim 24 wherein the step of treating said structural material comprises melting and solidifying said structural material.

29. An electrophoretic display comprising:

a plurality of display elements, each display element including;

a capsule having a first surface and a second surface and containing a structural portion, said structural portion adjacent to at least a portion of said second surface and oriented at an oblique angle relative to said second surface of said capsule to create a display portion of said capsule wherein one of said first surface and said second surface has a larger projected area than the other of said first surface and said second surface, said projected areas being measured when viewed in an intended viewing direction, said display portion including;

a suspending fluid; and

at least one particle dispersed within said suspending fluid; and

a first substrate adapted to receive said plurality of display elements.

30. The display of claim 29 wherein each of said display elements is individually addressable.

31. A method of manufacturing an electrophoretic display comprising the steps of:

manufacturing a plurality of display elements, each display element being manufactured by a process comprising the steps of;

encapsulating within a capsule a suspending fluid having a first optical property, at least one particle dispersed within said suspending fluid and having a second optical property different from said first optical property, and a structural material;

providing a substrate adapted to receive said plurality of display elements;

situating at least one of said plurality of display elements on said substrate;

orienting said substrate in a predetermined orientation; and

treating said structural material within each of said plurality of capsules to form within each of said plurality of capsules a display portion having a first surface, a second surface and a structural portion, said structural portion adjacent to at least a portion of said second surface and oriented at an oblique angle relative to said second surface, one of said first surface and said second surface having a larger projected area than the other of said first surface and said second surface, said projected areas being measured when viewed in an intended viewing direction.

32. The method of claim 31 comprising the additional step of providing electrodes adapted to address each of said display elements individually.

33. An electrophoretic display element comprising:

a capsule having a first surface and a second surface, wherein said first surface and said second surface comprise different projected areas, said projected areas being measured when viewed in an intended viewing direction, and wherein said first surface and said second surface are relatively oblique, said capsule containing;

a suspending fluid; and

at least one particle dispersed within said suspending fluid;

wherein application of a first electrical field causes the at least one particle to migrate towards said first surface and application of a second electrical field causes the at least one particle to migrate towards said second surfacer wherein said first surface.

34. An electrophoretic display element comprising:

a capsule having a first surface and a second surface, said first surface having a larger projected surface area than a projected surface area of said second surface when both surfaces are viewed in an intended viewing direction, said capsule containing;

a suspending fluid; and

at least one particle dispersed within said suspending fluid;

wherein application of a first electrical field causes the at least one particle to migrate towards said first surface and application of a second electrical field causes the at least one particle to migrate towards said second surface, and wherein a cross section of said element comprises a polygon of N sides, where N ranges from 5 to 12.

35. The display element of claim 34 wherein said polygon comprises a regular polygon.