Conductive layer to reduce drive voltage in displays

• US 7,564,528 B2
• Filed: 05/20/2005
• Issued: 07/21/2009
• Est. Priority Date: 05/20/2005
• Status: Expired due to Fees

• Current Assignee: Industrial Technology Research Institute
• Original Assignee: Industrial Technology Research Institute
• Inventors: Burberry, Mitchell S., Weiner, Megan L., Rankin, JR., Charles M.
• Primary Examiner(s): Caley, Michael H
• Application Number:
  US11/133,822
• Publication Number:
  US 20060262245A1
• Time in Patent Office: 1,523 Days
• Field of Search: 349/86, 349/138
• US Class Current: 349/138
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/133707 Structures for producing distorted electric fields, e.g. bumps, protrusions, recesses, slits in pixel electrodes
• CPC Class Codes: G02F 1/13718 based on a change of the texture state of a cholesteric liquid crystal
• CPC Class Codes: G02F 1/1391 Bistable or multi-stable liquid crystal cells G02F1/141 takes precedence
• CPC Class Codes: G02F 1/167 by electrophoresis

Abstract

The present invention relates to a display comprising a substrate, an electrically modulated imaging layer, at least one conductive layer, and a drive voltage-reducing layer between said conductive layer and said electrically modulated imaging layer, wherein said drive voltage-reducing layer has an SER greater than 10⁹ ohms per square and a method for imaging the display.

Claims

1. A bistable matrix-addressable display comprising a substrate, an electrically modulated imaging layer, at least a first patterned conductive layer patterned with non-conductive spaces between adjacent conductive areas, a drive voltage-reducing layer between said first patterned conductive layer and said electrically modulated imaging layer, and at least a second conductor on the side of said bistable electrically modulated imaging layer opposite said first conductor, wherein said drive voltage-reducing layer is configured to restrict spreading of an electric field from portions of said drive voltage-reducing layer disposed adjacent to said conductive areas into portions of said drive voltage-reducing layer disposed adjacent to said non-conductive spaces.

2. The bistable display of claim 1 wherein said bistable electrically modulated imaging layer comprises a liquid crystal material.

3. The bistable display of claim 1 wherein said bistable electrically modulated imaging layer comprises a polymer dispersed chiral nematic liquid crystal material.

4. The bistable display of claim 1 wherein said bistable electrically modulated imaging layer comprises an electrophoretic material.

5. The bistable display of claim 1 wherein said at least first conductive layer includes at least one transparent conductive layer.

6. The bistable display of claim 1 wherein said a drive voltage-reducing layer is transparent.

7. The bistable display of claim 1 wherein said drive voltage-reducing layer comprises at least one member selected from the group consisting of conjugated conducting polymers, conducting carbon particles, crystalline semiconductor particles, amorphous semiconductive fibrils, continuous conductive metal and semiconducting thin films.

8. The bistable display of claim 1 wherein said drive voltage-reducing layer comprises electronically conductive metal-containing particles.

9. The bistable display of claim 8 wherein said electronically conductive metal-containing particles are semiconducting metal oxides.

10. The bistable display of claim 8 wherein said electronically conductive metal-containing particles are conductive crystalline inorganic oxides, conductive metal antimonates, or conductive inorganic non-oxides.

11. The bistable display of claim 1 wherein said drive voltage-reducing layer comprises electronically conductive polymer.

12. The bistable display of claim 11 wherein said electronically conductive polymer is at least one member selected from the group consisting of substituted or unsubstituted polythiophenes, substituted or unsubstituted polypyrroles, and substituted or unsubstituted polyanilines.

13. The bistable display of claim 1 wherein said drive voltage-reducing layer contains polythiophene (PEDOT) particles.

14. The bistable display of claim 1 wherein said drive voltage-reducing layer contains carbon particles

15. The bistable display of claim 1 wherein said electrically modulated imaging layer is a wet-coated aqueous-based electrically modulated imaging layer and said drive voltage-reducing layer is a wet-coated aqueous-based drive voltage-reducing layer.

16. The bistable display of claim 1 wherein said at least first one conductor is located between said substrate and said bistable electrically modulated imaging layer.

17. The bistable display of claim 1 wherein said at least first conductor is located on the side of said bistable electrically modulated imaging layer opposite said substrate.

18. The bistable display of claim 1 wherein said drive voltage-reducing layer has a sheet resistance (SER) of from 2×

10⁹ to 2×

10¹¹ ohms/square.

19. The bistable display of claim 1 wherein said drive voltage-reducing layer comprises a colorant having a contrasting color to the reflection maximum of said bistable electrically modulated imaging layer.

20. A method of imaging a bistable matrix-addressable display element comprising:

providing a bistable matrix-addressable display comprising a substrate, an electrically modulated imaging layer, a first patterned conductive layer with non-conductive spaces between adjacent conductive areas, a drive voltage-reducing layer between said first conductive layer and said electrically modulated imaging layer, and a second conductive layer on the side of said bistable electrically modulated imaging layer opposite said first conductor layer, wherein said drive voltage-reducing layer is configured to restrict spreading of an electric field from portions of said drive voltage-reducing layer disposed adjacent to said conductive areas into portions of said drive voltage-reducing layer disposed adjacent to said non-conductive spaces;

identifying an area to be updated of said bistable matrix-addressable display; and

applying a sequence of drive signals.