Non-spherical cavity electrophoretic displays and materials for making the same

• US 7,391,555 B2
• Filed: 06/27/2006
• Issued: 06/24/2008
• Est. Priority Date: 07/20/1995
• Status: Expired due to Fees

• Current Assignee: E Ink Holdings Incorporated
• Original Assignee: E Ink Holdings Incorporated
• Inventors: Albert, Jonathan D., Comiskey, Barrett
• Primary Examiner(s): Choi; William C
• Application Number:
  US11/426,672
• Publication Number:
  US 20060245038A1
• Time in Patent Office: 728 Days
• Field of Search: 359/296, 345/107, 430/32
• US Class Current: 359/296
• CPC Class Codes: B25B 13/461 with concentric driving and driven member
• CPC Class Codes: B41J 3/4076 printing on rewritable, bistable "electronic paper" by a focused electric or magnetic field
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: G02B 26/005 based on electrowetting
• 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 1/133348 Charged particles addressed liquid crystal cells, e.g. controlled by an electron beam
• CPC Class Codes: G02F 1/13336 Combining plural substrates to produce large-area displays, e.g. tiled displays
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/1343 Electrodes reflective electrodes G02F1/133553
• CPC Class Codes: G02F 1/1345 Conductors connecting electrodes to cell terminals
• CPC Class Codes: G02F 1/135 Liquid crystal cells structurally associated with a photoconducting or a ferro-electric layer, the properties of which can be optically or electrically varied G02F1/133348 takes precedence
• CPC Class Codes: G02F 1/1365 in which the switching element is a two-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G02F 1/16757 Microcapsules
• CPC Class Codes: G02F 1/1681 having two or more microcells partitioned by walls, e.g. of microcup type
• CPC Class Codes: G02F 1/172 based on a suspension of orientable dipolar particles, e.g. suspended particles displays
• CPC Class Codes: G02F 2001/1678 characterised by the composition or particle type
• CPC Class Codes: G02F 2202/12 photoconductor
• CPC Class Codes: G02F 2202/28 Adhesive materials or arrangements
• CPC Class Codes: G06F 15/0283 : for data storage and retrieval
• CPC Class Codes: G06K 19/07703 : the interface being visual
• 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: H01L 27/12 : the substrate being other than a semiconductor body, e.g. an insulating body
• CPC Class Codes: H10K 10/46 : Field-effect transistors, e.g. organic thin-film transistors [OTFT] H10K10/43 takes precedence
• CPC Class Codes: H10K 10/462 : Insulated gate field-effect transistors [IGFETs]
• CPC Class Codes: H10K 19/00 : Integrated devices, or assemblies of multiple devices, comprising at least one organic element specially adapted for rectifying, amplifying, oscillating or switching, covered by group H10K10/00
• CPC Class Codes: H10K 85/113 : Heteroaromatic compounds comprising sulfur or selene, e.g. polythiophene
• CPC Class Codes: H10K 85/114 : Poly-phenylenevinylene; Derivatives thereof
• CPC Class Codes: H10K 85/20 : Carbon compounds, e.g. carbon nanotubes or fullerenes
• CPC Class Codes: H10K 85/30 : Coordination compounds
• CPC Class Codes: H10K 85/311 : Phthalocyanine
• CPC Class Codes: H10K 85/60 : Organic compounds having low molecular weight H10K85/10 - H10K85/50 take precedence
• CPC Class Codes: H10K 85/611 : Charge transfer complexes
• CPC Class Codes: H10K 85/615 : Polycyclic condensed aromatic hydrocarbons, e.g. anthracene

Abstract

Disclosed herein are novel electrophoretic displays and materials useful in fabricating such displays. In particular, novel encapsulated displays are disclosed. Particles encapsulated therein are dispersed within a suspending, or electrophoretic, fluid. This fluid may be a mixture of two or more fluids or may be a single fluid. The displays may further comprise particles dispersed in a suspending fluid, wherein the particles contain a liquid. In either case, the suspending fluid may have a density or refractive index substantially matched to that of the particles dispersed therein. Finally, also disclosed herein are electro-osmotic displays. These displays comprise at least one capsule containing either a cellulosic or gel-like internal phase and a liquid phase, or containing two or more immiscible fluids. Application of electric fields to any of the electrophoretic displays described herein affects an optical property of the display.

Claims

1. An encapsulated electrophoretic display having a viewed surface and comprising a polymer matrix and at least one elastomeric capsule disposed in the polymer matrix, the elastomeric capsule comprising a capsule wall and an internal phase enclosed within the capsule wall, the internal phase comprising a suspending fluid and at least one electrophoretic particle, the elastomeric capsule having a substantially flat surface that is substantially parallel to or coplanar with the viewed surface, and side walls extending substantially perpendicular to the viewed surface so that the capsule has substantially the form of a polyhedron.

2. A display according to claim 1 wherein the aspect ratio of width to height for each capsule is greater than about 1.2.

3. A display according to claim 2 wherein the aspect ratio is greater than about 1.5.

4. A display according to claim 3 wherein the aspect ratio is greater than about 1.75.

5. A display according to claim 1 wherein the volume fraction of the polymer matrix is between about 0.05 and about 0.2.

6. A display according to claim 1 wherein the capsule has a substantially flat rear surface parallel to the viewed surface.

7. A display according to claim 1 wherein the at least one electrophoretic particle comprises titania.

8. A display according to claim 7 wherein the titania is coated with a metal oxide.

9. A display according to claim 1 wherein the at least one electrophoretic particle comprises carbon black.

10. A display according to claim 1 further comprising at least one electrode for applying an electric field to the capsule.

11. An encapsulated electrophoretic display having a viewed surface and at least one deformable capsule, the deformable capsule comprising a capsule wall and an internal phase enclosed within the capsule wall, the internal phase comprising a suspending fluid and at least one electrophoretic particle, the deformable capsule having a substantially flat surface that is substantially parallel to or coplanar with the viewed surface, and side walls extending substantially perpendicular to the viewed surface so that the capsule has substantially the form of a polyhedron.

12. A display according to claim 11 wherein the aspect ratio of width to height for each capsule is greater than about 1.2.

13. A display according to claim 12 wherein the aspect ratio is greater than about 1.5.

14. A display according to claim 13 wherein the aspect ratio is greater than about 1.75.

15. A display according to claim 11 wherein the capsule has a substantially flat rear surface parallel to the viewed surface.

16. A display according to claim 11 wherein the at least one electrophoretic particle comprises titania.

17. A display according to claim 16 wherein the titania is coated with a metal oxide.

18. A display according to claim 11 wherein the at least one electrophoretic particle comprises carbon black.

19. A display according to claim 11 further comprising at least one electrode for applying an electric field to the capsule.

20. A process for forming an electrophoretic display, the process comprising:

forming a capsule/binder mixture comprising a plurality of capsules in a polymer binder, each of the capsules comprising a suspending fluid and at least one electrophoretic particle;

coating a layer of the capsule/binder mixture on a substrate;

drying or curing the binder, thereby causing the binder to shrink and form a viewed surface, and the capsules to assume a form having a substantially flat surface that is substantially parallel to or coplanar with the viewed surface, and side walls extending substantially perpendicular to the viewed surface so that the capsules have substantially the form of polyhedra.