Reflective liquid crystal displays having multilayer rear substrates

• US 6,801,280 B2
• Filed: 01/14/2003
• Issued: 10/05/2004
• Est. Priority Date: 01/15/2002
• Status: Active Grant

• Current Assignee: Hong Kong University of Science and Technology
• Original Assignee: Hong Kong University of Science and Technology
• Inventors: Kwok, Hoi-Sing, Tang, Shu-Tuen, Fung, Kin Ming
• Primary Examiner(s): Kim, Robert H.
• Assistant Examiner(s): Schechter, Andrew
• Application Number:
  US10/341,255
• Publication Number:
  US 20030133063A1
• Time in Patent Office: 630 Days
• Field of Search: 349/113, 349/114, 349/115, 349/147
• US Class Current: 349/113
• CPC Class Codes: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605

Abstract

There is provided a reflective liquid crystal cell formed of a liquid crystal material disposed between first and second substrates. The first substrate is optically transparent and is formed with a coating of optically transparent and electrically conductive material on the side facing the liquid crystal material. The second substrate is formed with a plurality of coatings on the side facing the liquid crystal material. These coatings include in sequence a layer of metallic reflective material, a layer of electrically insulating material, a layer of na optically transparent and conductive material and a liquid crystal alignment layer.

Claims

1. A reflective liquid crystal display comprising a liquid crystal cell formed of liquid crystal material disposed between first and second substrates, wherein said first substrate is optically transparent and is formed with a coating of optically transparent and electrically conductive material on the side of said first substrate facing said liquid crystal material, said coating being further provided with a liquid crystal alignment layer, and wherein said second substrate is formed with a plurality of coatings on the side of the second substrate facing the liquid crystal material, said coatings comprising in sequence a layer of metallic reflective material deposited on the surface of the second substrate, a layer of an electrically insulating material, a layer of an optically transparent and electrically conductive material formed of the same material as said layer of metallic reflective material, and a liquid crystal alignment layer.

2. A display as claimed in claim 1 wherein the metallic reflective layer formed on the surface of said second substrate is divided into electrically disconnected regions.

3. A display as claimed in claim 2 wherein said regions are a pattern of regular geometric figures.

4. A display as claimed in claim 3 wherein said geometric figures include squares, rectangles, circles or polygons.

5. A display as claimed in claim 1 wherein the layer of reflective material formed on the surface of the second substrate is formed of a material selected from the group consisting of aluminium, gold, silver, chromium, titanium, tin, zinc and iron.

6. A display as claimed in claim 1 wherein the metallic reflective layer formed on said second substrate is formed with a partially light scattering surface.

7. A display as claimed in claim 6 wherein said partially light scattering surface is formed by varying the conditions of a metal deposition process to form said metallic layer.

8. A display as claimed in claim 1 wherein said metallic reflective layer is formed by sputtering in a partial vacuum or by vacuum evaporation.

9. A display as claimed in claim 1 wherein said metallic reflective layer is formed with a thickness of between 0.01 and 1 micron.

10. A display as claimed in claim 1 wherein said electrically conductive layer formed on said second substrate is between 0.01 to 1 micron in thickness.

11. A display as claimed in claim 1 wherein said electrically insulating layer is formed of a material selected from the group consisting of silicon oxide, aluminium oxide, magnesium oxide, zirconium oxide or titanium oxide.

12. A display as claimed in claim 1 wherein said electrically insulating layer is formed of an organic polymer material.

13. A display as claimed in claim 1 wherein said electrically insulating layer is at least 1 micron in thickness.

14. A display as claimed in claim 1 wherein said electrically insulating layer is formed by sputtering in a partial vacuum, or by vacuum evaporation or by spin coating.

15. A reflective liquid crystal display comprising a liquid crystal cell formed of a liquid crystal material disposed between first and second substrates, wherein said first substrate is optically transparent and is formed with a coating of optically transparent and electrically conductive material on the side of said first substrate facing said liquid crystal material, said coating being further provided with a liquid crystal alignment layer, and wherein said second substrate is formed with a plurality of coatings on the side of the second substrate facing the liquid crystal material, said coatings comprising in sequence a layer of electrically insulating reflective material deposited on the surface of the second substrate and having a partially light scattering surface, a layer of an optically transparent and electrically conductive material, and a liquid crystal alignment layer.

16. A display as claimed in claim 15 wherein said electrically insulating reflective layer is formed of a dye doped polymer material.