Encapsulated electrophoretic displays and methods and materials for making the same

• US 6,727,881 B1
• Filed: 08/27/1998
• Issued: 04/27/2004
• Est. Priority Date: 07/20/1995
• Status: Expired due to Fees

• Current Assignee: E Ink Holdings Incorporated
• Original Assignee: E Ink Holdings Incorporated
• Inventors: Loxley, Andrew, Zhang, Libing, Feeney, Robert, Albert, Jonathan D., Jacobson, Joseph M., Comiskey, Barrett, Drzaic, Paul, Morrison, Ian
• Primary Examiner(s): Shalwala, Bipin
• Assistant Examiner(s): LEWIS, DAVID LEE
• Application Number:
  US09/140,846
• Time in Patent Office: 2,070 Days
• Field of Search: 345/107, 345/48, 345/84, 345/85, 345/105, 345/108, 359/296, 348/86-90, 430/37, 430/47, 430/35, 427/212, 264/4.1, 428/402.24
• US Class Current: 345/107
• CPC Class Codes: B41J 2/01 Ink jet
• 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: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: C09D 11/30 Inkjet printing inks
• 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 1/172 based on a suspension of orientable dipolar particles, e.g. suspended particles displays
• CPC Class Codes: G02F 2202/12 photoconductor
• CPC Class Codes: G02F 2202/28 Adhesive materials or arrangements
• CPC Class Codes: G04B 47/00 Time-pieces combined with other articles which do not interfere with the running or the time-keeping of the time-piece clockwork cases for special purposes G04B37/12; clocks with magnifying glass built in the face G04B39/00; time-pieces in which parts or cases produce special effects, e.g. aesthetic effects, G04B45/00, particularly with inscriptions or pictures moved by hand G04B45/003, with specially shaped cases or parts G04B45/0069; combination of writing or drawing implements with devices for indicating time B43K29/087; combined with cameras, projectors, or photographic printing apparatus G03B29/00
• 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: G09G 2380/02 : Flexible displays
• CPC Class Codes: G09G 3/035 : for flexible display surfaces
• CPC Class Codes: G09G 3/344 : based on particles moving in a fluid or in a gas, e.g. electrophoretic devices electrophoretic devices per se G02F1/167
• CPC Class Codes: H01L 27/12 : the substrate being other than a semiconductor body, e.g. an insulating body
• CPC Class Codes: H05K 1/097 : Inks comprising nanoparticles and specially adapted for being sintered at low temperature H05K1/095 takes precedence
• CPC Class Codes: H05K 3/105 : by conversion of non-conductive material on or in the support into conductive material, e.g. by using an energy beam
• CPC Class Codes: H05K 3/1241 : by ink-jet printing or drawing by dispensing
• 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 10/466 : Lateral bottom-gate IGFETs comprising only a single gate
• 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 medium, comprising a capsule comprising particles dispersed in a suspending fluid, wherein said particles contain a liquid and move in response to an applied electric field.

2. The display of claim 1, wherein said display further comprises the capsule in a binder.

3. The display of claim 1, wherein said liquid is selected from the group consisting of a dye and a pigment.

4. The display of claim 1, further comprising a plurality of granules dispersed within said liquid.

5. The display of claim 4, wherein said plurality of granules are selected from the group consisting of scattering pigments, absorbing pigments, and luminescent particles.

6. The display of claim 1, wherein said capsule is between about 5 μ

m and about 200 μ

m in diameter.

7. The display of claim 1, wherein said particle is between about 10 nm and about 1 μ

m in diameter.

8. The display of claim 1, wherein said particle comprises a polymeric layer surrounding said liquid.

9. The display of claim 2, wherein application of an electric field affects the dispersion of said plurality of particles within said suspending fluid, thereby modulating the optical property of said capsule.

10. The display of claim 1, wherein said suspending fluid has a density substantially matched to the density of said particles.

11. The display of claim 1, wherein either of said suspending fluid or said liquid is a halogenated hydrocarbon.

12. The display of claim 11, wherein either of said suspending fluid or said liquid is tetrachloroethylene.

13. The display of claim 11, wherein either of said suspending fluid or said liquid is poly(chlorotrifluoroethylene) polymer.

14. The display of claim 13, wherein said polymer has a degree of polymerization from about 2 to about 10.

15. The display of claim 10, wherein either of said suspending fluid or said liquid is a mixture of two or more fluids.

16. The display of claim 1, further comprising an oil-soluble dye in either of said suspending fluid or said liquid, said dye being selected from the group consisting of anthraquinone, azo, and triphenylmethane type dyes.

17. The display of claim 1, further comprising a surfactant in said first suspending fluid.

18. The display of claim 17, wherein said surfactant comprises sodium dodecylsulfate.

19. The display of claim 2, wherein said binder is selected from the group consisting of water-soluble polymers, water-dispersed polymers, oil-soluble polymers, thermoset polymers, thermoplastic polymers, uv-cured polymers, radiation-cured polymers, gelatin arabic, gum arabic, polyurethanes, polyamides, urea formaldehyde resin, melamine formaldehyde resin, cellulose, cellulose derivatives, polyvinylacetates, and polyvinylalcohol.

20. The display of claim 19, wherein said binder further comprises an additive selected from the group consisting of organic surfactants, organic salts, organic particles, and organic pigments.

21. The display of claim 4, wherein said granules are titania.

22. The display of claim 4, wherein said granules are metal oxide-coated titania.

23. The display of claim 22, wherein said metal oxide is selected from the group consisting of aluminum oxide and silicon oxide.

24. The display of claim 23, wherein said metal oxide-coated titania comprises two layers of metal oxide coating.

25. The display of claim 24, wherein said titania is coated with both aluminum oxide and silicon oxide in either order.

26. The display of claim 4, further comprising a charge control agent.

27. The display of claim 26, wherein said charge control agent is polyisobutylenesuccinimide.

28. The display of claim 26, wherein said charge control agent is a metal soap.

29. The display of claim 26, wherein said charge control agent is lecithin.

30. A process for creating an encapsulated electrophoretic display medium, comprising the steps of:

(a) encapsulating a dye in a liquid into a plurality of first electrophoretic capsules; and

(b) encapsulating said plurality of first capsules into a second capsule in a binder to form said display medium.

31. The process of claim 30, wherein step (a) comprises encapsulating a dye comprising at least one dye and a polymerizable fluid into a plurality of first capsules.

32. The process of claim 31, further comprising the step of polymerizing said polymerizable fluid after step (a), thereby forming a solid polymer inside each capsule of said plurality of first capsules.

33. The process of claim 30, wherein said dye is polymerizable.

34. The process of claim 33, further comprising the step of polymerizing said dye after step (a), thereby forming a solid polymer inside each capsule of said plurality of first capsules.

35. The process of claim 32, wherein said polymerizable fluid may be polymerized by a process selected from the group consisting of thermal, photochemical and chemical diffusion.

36. The process of claim 34, further comprising the step of polymerizing said dye by a process selected from the group consisting of thermal, photochemical and chemical diffusion.

37. The process of claim 31, wherein said polymerizable fluid is selected from the group consisting of PMMA, polystyrene, polyethylene, polypropylene, phenolic resins, polyesters, polyacrylates, polymethacrylates, ethylene-vinyl acetate copolymers, ethylene acrylic acid, methacrylic acid, and acrylic copolymers and terpolymers.