Flicker-free reflective liquid crystal cell

• US 5,764,324 A
• Filed: 01/22/1997
• Issued: 06/09/1998
• Est. Priority Date: 01/22/1997
• Status: Expired due to Term

• Current Assignee: AU Optronics Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Lu, Minhua, Yang, Kei-Hsiung
• Primary Examiner(s): GROSS, ANITA P
• Application Number:
  US08/787,411
• Time in Patent Office: 503 Days
• Field of Search: 349/25, 349/113, 349/147
• US Class Current: 349/113
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/13394 spacers regularly patterned on the cell subtrate, e.g. walls, pillars G02F1/133377 takes precedence
• CPC Class Codes: G02F 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making
• CPC Class Codes: G02F 1/136227 Through-hole connection of the pixel electrode to the active element through an insulation layer
• CPC Class Codes: G02F 1/136277 formed on a semiconductor substrate, e.g. of silicon

Abstract

A reflective liquid crystal cell for AMLCDs is provided wherein the reflective electrode may be passivated with an insulating film such as silicon oxide. In addition, the liquid crystal cell of the present invention may include a conducting transparent electrode that has a work function substantially equal to the work function of the reflective electrode in the cell. The reflective electrode may include a transparent conductive layer such as ITO, or may include an integer number of film pairs, wherein the film pair comprises a first dielectric film having a low index of refraction and a second dielectric film having a high index of refraction.

Claims

1. A liquid crystal cell for a liquid crystal display device comprising:

a transparent electrode;

a reflective electrode; and

a liquid crystal material disposed between said transparent electrode and said reflective electrode;

wherein work functions of said transparent electrode and said reflective electrode are approximately equal and wherein said reflective electrode comprises a transparent conductive layer and a reflecting metal layer.

2. The liquid crystal cell of claim 1, wherein said reflecting metal layer comprises aluminum.

3. The liquid crystal cell of claim 2, wherein said transparent conductive layer comprises ITO.

4. The liquid crystal cell of claim 1, wherein the thickness of said transparent conductive layer is approximately a half-wave plate for a predetermined incident light.

5. The liquid crystal cell of claim 1, wherein said liquid crystal cell is used in a spatial light modulator device.

6. A liquid crystal cell for a liquid crystal display device comprising:

a transparent electrode;

a reflective electrode; and

a liquid crystal material disposed between said transparent electrode and said reflective electrode;

wherein work functions of said transparent electrode and said reflective electrode are approximately equal, and wherein said reflective electrode comprises at least one layer of dielectric material disposed between a transparent conductive layer and a reflecting metal layer.

7. The liquid crystal cell of claim 6, wherein said transparent conductive layer comprises ITO.

8. The liquid crystal cell of claim 6, wherein said dielectric material comprises silicon dioxide.

9. The liquid crystal cell of claim 6, wherein the thickness of said at least one layer of dielectric material and said transparent conductive layer is optimized to achieve high reflectivity.

10. The liquid crystal cell of claim 8, wherein said reflective electrode comprises at least one pair of layers of dielectric material.

11. The liquid crystal cell of claim 10, wherein a first layer of said at least one pair of layers of dielectric material has a lower index of refraction with respect to a second layer of said at least one pair of layers of dielectric material.

12. The liquid crystal cell of claim 11, wherein said transparent conductive layer comprises ITO and said dielectric material comprises silicon dioxide.

13. The liquid crystal cell of claim 6, wherein said liquid crystal cell is used in a spatial light modulator device.