Single polarized LCD consisting of particular twist angle and thickness-birefringence product

• US 6,091,477 A
• Filed: 03/25/1997
• Issued: 07/18/2000
• Est. Priority Date: 03/25/1997
• Status: Expired due to Term

• 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
• Primary Examiner(s): Sikes, Willaim L.
• Assistant Examiner(s): TON, MINH TOAN T
• Application Number:
  US08/826,815
• Time in Patent Office: 1,211 Days
• Field of Search: 349/96, 349/113, 349/117, 349/121, 349/180, 349/181
• US Class Current: 349/180
• CPC Class Codes: G02F 1/1396 the liquid crystal being selectively controlled between a twisted state and a non-twisted state, e.g. TN-LC cell G02F1/141 takes precedence

Abstract

A liquid crystal display is described in which the need for a conventional output polarizer is eliminated and the display comprises only a liquid crystal cell, a single input polarizer, a reflector placed behind the cell, and a retardation film placed between the reflector and the cell. A Jones matrix simulation approach is used in order to obtain the parameters corresponding to solution spaces for the above design and several combinations are disclosed that give good results.

Claims

1. A liquid crystal display consisting essentially of a liquid crystal cell, a single polarizer placed in front of said cell, a reflector placed behind said cell, and a retardation film provided between said reflector and said cell, wherein a is 45°

±

10° and

a product dΔ

n of said liquid crystal cell is larger than 0.5 μ

m and less than 2.5 μ

m.

5. A display as claimed in any of claims 1 to 4 wherein an (χ

) between a of said retardation film and a on the side of the liquid crystal cell through which light first enters is chosen such that χ

=0°

whereby said display is normally dark.

6. A display as claimed in any of claims 1 to 4 wherein an (χ

) between a of said retardation film and a on the side of the liquid crystal cell through which light first enters is chosen such that χ

=45°

whereby said display is normally bright.

2. A liquid crystal display consisting essentially of a liquid crystal cell, a single polarizer placed in front of said cell, a reflector placed behind said cell, and a retardation film provided between said reflector and said cell, where the twist angle is 135°

±

10° and

the thickness-birefringence product dΔ

n of said liquid crystal cell is larger than 0.3 μ

m and less than 2.5 μ

m.

3. A liquid crystal display consisting essentially of a liquid crystal cell, a single polarizer placed in front of said cell, a reflector placed behind said cell, and a retardation film provided between said reflector and said cell, wherein the twist angle is 225°

±

10° and

the thickness-birefringence product dΔ

n of said liquid crystal cell is larger than 0.8 μ

m and less than 2.5 μ

m.

4. A liquid crystal display consisting essentially of a liquid crystal cell, a single polarizer placed in front of said cell, a reflector placed behind said cell, and a retardation film provided between said reflector and said cell, wherein the twist angle is 315°

±

10° and

the thickness-birefringence produce dΔ

n of said liquid crystal cell is larger than 0.5 μ

m and less than 2.5 μ

m.