Retroreflective electrophoretic displays and materials for making the same

• US 7,071,913 B2
• Filed: 06/29/2001
• Issued: 07/04/2006
• 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: Zhang, Libing, Feeney, Robert, Loxley, Andrew, 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:
  US09/896,546
• Publication Number:
  US 20050035941A1
• Time in Patent Office: 1,831 Days
• Field of Search: 359/296, 359/536, 359/537, 359/68, 359/618, 345/107, 345/85, 349/63, 349/86, 427/288, 204/606
• 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 1/1677 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 3/344 : based on particles moving in a fluid or in a gas, e.g. electrophoretic devices electrophoretic devices per se G02F1/167
• CPC Class Codes: G09G 3/3473 : based on light coupled out of a light guide, e.g. due to scattering, by contracting the light guide with external means
• 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, comprising one or more species of particles, each having a distinct electrophoretic mobility, wherein at least one of said species of particles comprises a retroreflective corner cube, said display being capable of displaying multiple optical states through electrophoretic movement of said particles.

2. The display of claim 1, wherein said display comprises a capsule in a binder encapsulating said one or more species of particles.

3. The display of claim 1, wherein at least one of said one or more species of particles has a reflective coating.

4. The display of claim 1, further comprising a suspending fluid having a density substantially matched to the density of said one or more species of particles.

5. The display of claim 4, wherein said suspending fluid is a halogenated hydrocarbon.

6. 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 poly(vinvl alcohol).

7. The display of claim 6, wherein said binder further comprises an additive selected from the group consisting of organic surfactants, organic salts, organic particles, and organic pigments.

8. The display of claim 1, wherein said one or more species of particles are titania.

9. The display of claim 1, wherein said one or more species of particles are metal oxide-coated titania.

10. The display of claim 9, wherein said metal oxide is selected from the group consisting of aluminum oxide and silicon oxide.

11. The display of claim 1, wherein said display comprises a polymer-dispersed display where said one or more species of particles are encapsulated in multiple cavities disposed in a polymeric matrix.

12. An electrophoretic display comprising a first species of particles and a second species of particles both disposed in multiple cavities in a polymeric matrix, each species of particles having a distinct electrophoretic mobility, said first species of particles being retroreflective, said first and second species of particles being capable of migrating between at least a first position and a second position, and

wherein said first and second species of particles in said first position at least partially allow said first species of particles to retroreflect an incident light, and in said second position at least partially prevent said first species of particles from retroreflecting the incident light.

13. The display of claim 12 wherein said first species of particles comprises a corner cube.

14. The display of claim 12, wherein said first species of particles has a reflective coating.

15. The display of claim 12, further comprising a suspending fluid having a density substantially matched to the density of at least one of said first and second species of particles.

16. The display of claim 12 wherein said display is of the emulsion or phase separation type display.

17. The display of claim 12, wherein at least one of said first and second species of particles comprises titania.

18. An electrophoretic display comprising a species of electrophoretic particles in a suspending fluid, and a retroreflective substrate, said display being capable of displaying multiple optical states through electrophoretic movement of at least said species of particles, said species of particles being capable of migrating between at least a first position and a second position, and

wherein said species of particles in said first position at least partially allow said substrate to retroreflect an incident light, and in said second position at least partially prevent said substrate from retroreflecting the incident light.

19. The display of claim 18 wherein said substrate comprises a corner cube.

20. The display of claim 18, wherein said species of particles is disposed in a cavity in a polymeric matrix.

21. The display of claim 20 wherein said display is of the emulsion or phase separation type display.

22. The display of claim 18, wherein said species of particles is encapsulated in at least one capsule in a binder.

23. The display of claim 18 further comprising a second species of particle having an electrophoretic mobility distinct from said first species of particles.

24. The display of claim 18, wherein said species of particles comprises titania.