Optical element including an absorptive and reflective polarizer having particular orientation

• US 6,747,716 B2
• Filed: 03/18/2002
• Issued: 06/08/2004
• Est. Priority Date: 04/30/1998
• Status: Expired due to Term

• Current Assignee: BOE Technology Group Co., Ltd.
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Tsuda, Atsunari, Kuroiwa, Masahiro, Miwa, Naonori
• Primary Examiner(s): CHOWDHURY, TARIFUR RASHID
• Application Number:
  US10/098,489
• Publication Number:
  US 20020089622A1
• Time in Patent Office: 813 Days
• Field of Search: 349/96, 349/98, 349/117, 349/69, 349/112, 345/94
• US Class Current: 349/96
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one
• CPC Class Codes: G02F 2203/02 reflective

Abstract

The liquid crystal device of the present invention effectively prevents reversion of bright/dark states between a reflective display mode and a transmissive display mode. The liquid crystal device includes a first absorptive polarizer, which receives light from outside; a liquid crystal cell, which receives light emitted from the first absorptive polarizer; a second absorptive polarizer, which receives light emitted from the liquid crystal cell; and a reflective polarizer, which receives light emitted from the second absorptive polarizer. The reflective polarizer has an axis of reflection in a predetermined direction to reflect at least part of light that has been transmitted through the first absorptive polarizer, the liquid crystal cell, and the second absorptive polarizer to be incident on the reflective polarizer. The reflective polarizer partially transmits light including a linearly polarized light component which is included in light entering the reflective polarizer from an opposite side to the second absorptive polarizer and which is to be transmitted through the second absorptive polarizer. The first absorptive polarizer has an axis of transmission in a specific direction to cause light, which has been reflected by the reflective polarizer and transmitted through the second absorptive polarizer, to be transmitted through the first absorptive polarizer.

Claims

1. An optical element, comprising:

an absorptive polarizer having an axis of absorption and an axis of transmission; and

a reflective polarizer positioned to face the absorptive polarizer and having an axis of reflection and an axis of transmission,

wherein the reflection axis of the reflective polarizer and the transmission axis of the absorptive polarizer intersect at an angle between 15 and 25 degrees.

2. An optical element according to claim 1, further comprising a diffusing plate arranged between the absorptive polarizer and the refractive polarizer.

3. An optical element according to claim 1, further comprising a retardation film arranged between the absorptive polarizer and the reflective polarizer.

4. An optical element, comprising:

a diffusing plate having at least two surfaces, each of the surfaces being opposite to the other;

an absorptive polarizer facing one of the surfaces and having an axis of absorption and an axis of transmission; and

a reflective polarizer facing the other of the surfaces and having an axis of reflection and an axis of transmission,

wherein the reflection axis of the reflective polarizer and the transmission axis of the absorptive polarizer intersect at an angle between 15 and 25 degrees.

5. An optical element, comprising:

a retardation film having at least two surfaces, each of the surfaces being opposite to the other;

an absorptive polarizer facing one of the surfaces and having an axis of absorption and an axis of transmission; and

a reflective polarizer facing the other of the surfaces and having an axis of reflection and an axis of transmission,

wherein the reflection axis of the reflective polarizer and the transmission axis of the absorptive polarizer intersect at an angle between 15 and 25 degrees.

6. A liquid crystal display device, comprising:

a liquid crystal layer;

a light source emitting light towards the liquid crystal layer; and

an optical element positioned between the liquid crystal layer and the light source, the optical element comprising;

an absorptive polarizer having an axis of absorption and an axis of transmission; and

a reflective polarizer positioned to face the absorptive polarizer and having an axis of reflection and an axis of transmission,

wherein the optical element is disposed such that the absorptive polarizer faces the liquid crystal layer and the reflective polarizer faces the light source and the reflection axis of the reflective polarizer and the transmission axis of the absorptive polarizer intersect at an angle between 15 and 25 degrees.

7. A liquid crystal display device according to claim 6, further comprising a diffusing plate between the absorptive polarizer and the reflective polarizer.

8. A liquid crystal display device according to claim 6, further comprising a retardation film arranged between the absorptive polarizer and the reflective polarizer.

9. A liquid crystal display device according to claim 6, wherein the device is capable of performing both of a reflective display mode and a transmissive display mode.

10. An electronic apparatus comprising a liquid crystal display device of claim 6.