Retroreflective electrophoretic displays and materials for making the same

• US 6,249,271 B1
• Filed: 02/25/2000
• Issued: 06/19/2001
• Est. Priority Date: 07/20/1995
• Status: Expired due to Fees

• Current Assignee: E Ink Corporation (E Ink Holdings Incorporated)
• Original Assignee: E Ink Corporation (E Ink Holdings Incorporated)
• Inventors: Loxley, Andrew, Albert, Jonathan D., Jacobson, Joseph M., Comiskey, Barrett, Zhang, Libing, Drzaic, Paul, Feeney, Robert, Morrison, Ian
• Primary Examiner(s): Shalwala, Bipin
• Assistant Examiner(s): LEWIS, DAVID LEE
• Application Number:
  US09/513,411
• Time in Patent Office: 480 Days
• Field of Search: 345/107, 428/323, 359/296, 359/529, 359/530, 359/538, 359/539, 359/541, 349/86, 349/89
• US Class Current: 345/107
• CPC Class Codes: B41J 2/01 Ink jet
• CPC Class Codes: B41J 2/02 generating a continuous 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: C09D 11/50 Sympathetic, colour changing or similar 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 1/134309 characterised by their geometrical arrangement
• CPC Class Codes: G02F 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making
• 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 1/1677 : Structural association of cells with optical devices, e.g. reflectors or illuminating devices
• 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 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
• CPC Class Codes: Y10S 977/773 : Nanoparticle, i.e. structure having three dimensions of 100 nm or less
• CPC Class Codes: Y10S 977/952 : Display

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 element, the element comprising a retroreflective capsule defined by a wall and containing a suspending fluid and a plurality of electrophoretically mobile particles that can electrophoretically migrate between at least a first and a second position within the capsule, wherein the wall refracts and reflects light to substantially retroreflect incident light when the plurality of particles are at the first position, and wherein the wall is prevented from retroreflecting the incident light when the plurality of particles are at the second position.

2. The element of claim 1 wherein incident light retroreflects away from a point of observation.

3. The element of claim 1 wherein incident light retroreflects towards a point of observation.

4. The element of claim 1 wherein the suspending fluid has a density substantially matched to the density of at least a portion of the plurality of particles.

5. The element of claim 1 wherein the suspending fluid comprises a halogenated hydrocarbon.

6. The element of claim 5 wherein the halogenated hydrocarbon is tetrachloroethylene.

7. The element of claim 5 wherein the halogenated hydrocarbon is a poly(chlorotrifluoroethylene) polymer.

8. The element of claim 7 wherein the polymer has a degree of polymerization from about 2 to about 10.

9. The element of claim 1 wherein the suspending fluid comprises a mixture of two or more fluids.

10. The element of claim 1 further comprising an oil-soluble dye in the suspending fluid, the dye being selected from the group consisting of anthraquinone, azo, and triphenylmethane type dyes.

11. The element of claim 1 further comprising a surfactant in the suspending fluid.

12. The element of claim 11 wherein the surfactant comprises sodium dodecylsulfate.

13. The element of claim 1 further comprising a charge control agent.

14. The element of claim 13 wherein the charge control agent is a polyisobutylene succinimide.

15. The element of claim 13 wherein the charge control agent is a metal soap.

16. The element of claim 13 wherein the charge control agent is lecithin.

17. The element of claim 1 wherein the plurality of particles comprises at least two species of particles.

18. The element of claim 1 wherein at least some of the plurality of particles absorb light.

19. The element of claim 1 wherein at least some of the plurality of particles reflect light.

20. An electrophoretic display comprising a plurality of the encapsulated electrophoretic elements of claim 1.

21. An electrophoretic display comprising a plurality of retroreflective capsules, each capsule defined by a wall and containing a suspending fluid and a plurality of electrophoretically mobile particles, wherein the particles can electrophoretically migrate between at least a first and a second position within the capsules, and wherein at least some of the walls refract and reflect light to substantially retroreflect incident light depending on the positions of the particles within the capsules and wherein at least some of the capsules are adjacent to an electrode.

22. The display of claim 21 wherein the display further comprises a binder adhered to the plurality of capsules.

23. The display of claim 22 wherein the 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.

24. The display of claim 23 wherein the binder further comprises an additive selected from the group consisting of organic surfactants, organic salts, organic particles, and organic pigments.