Liquid crystal device and electronic apparatus using the same

• US 20020089622A1
• Filed: 03/18/2002
• Published: 07/11/2002
• Est. Priority Date: 04/30/1998
• Status: Active Grant

• Current Assignee: BOE Technology Group Co., Ltd.
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Kuroiwa, Masahiro, Miwa, Naonori, Tsuda, Atsunari
• Granted Patent: US 6,747,716 B2
• Time in Patent Office: Days
• 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. A liquid crystal device that modulates light responsive to given image signals, the liquid crystal device comprising:

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,

wherein 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, and 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, and

wherein 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.

2. A liquid crystal device in accordance with claim 1, further comprising:

a diffusing plate interposed between the second absorptive polarizer and the reflective polarizer.

3. A liquid crystal device in accordance with claim 1, wherein the predetermined direction of the reflection axis of the reflective polarizer is adjusted to cause a ratio of an amount of first light to an amount of second light to be not less than about 15% in a state where a linearly polarized light component having a predetermined first polarizing direction is emitted in a greatest amount from the liquid crystal cell towards the second absorptive polarizer, the first light being one that is reflected by the reflective polarizer and transmitted through the second absorptive polarizer, the liquid crystal cell, and the first absorptive polarizer, the second light being one that is incident on the first absorptive polarizer.

4. A liquid crystal device in accordance with claim 2, wherein the predetermined direction of the reflection axis of the reflective polarizer is adjusted to cause a ratio of an amount of first light to an amount of second light to be not less than about 15% in a state where a linearly polarized light component having a predetermined first polarizing direction is emitted in a greatest amount from the liquid crystal cell towards the second absorptive polarizer, the first light being one that is reflected by the reflective polarizer and transmitted through the second absorptive polarizer, the liquid crystal cell, and the first absorptive polarizer, the second light being one that is incident on the first absorptive polarizer.

5. A liquid crystal device in accordance with claim 1, further comprising:

a backlight that is disposed opposite to the second absorptive polarizer across the reflective polarizer,

wherein light emitted from the backlight is adjusted to have a color other than white, in order to cause color of a first light to be close to color of a second light, the first light being one that is emitted from the backlight and transmitted through the reflective polarizer, the second absorptive polarizer, the liquid crystal cell, and the first absorptive polarizer, the second light being one that comes from the outside and is transmitted through the first absorptive polarizer, the liquid crystal cell, and the second absorptive polarizer, subsequently reflected by the reflective polarizer, then transmitted through the second absorptive polarizer, the liquid crystal cell, and the first absorptive polarizer.

6. A liquid crystal device in accordance with claim 5, wherein the backlight comprises:

a light source; and

a color filter that adjusts color of light emitted from the light source.

7. An electronic apparatus comprising:

a display device, the display device including;

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,

wherein 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, and 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, and

wherein 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.

8. An electronic apparatus in accordance with claim 7, the display device further comprising:

a diffusing plate interposed between the second absorptive polarizer and the reflective polarizer.

9. An electronic apparatus in accordance with claim 7, wherein the predetermined direction of the reflection axis of the reflective polarizer is adjusted to cause a ratio of an amount of first light to an amount of second light to be not less than about 15% in a state where a linearly polarized light component having a predetermined first polarizing direction is emitted in a greatest amount from the liquid crystal cell towards the second absorptive polarizer, the first light being one that is reflected by the reflective polarizer and transmitted through the second absorptive polarizer, the liquid crystal cell, and the first absorptive polarizer, the second light being one that is incident on the first absorptive polarizer.

10. An electronic apparatus in accordance with claim 8, wherein the predetermined direction of the reflection axis of the reflective polarizer is adjusted to cause a ratio of an amount of first light to an amount of second light to be not less than about 15% in a state where a linearly polarized light component having a predetermined first polarizing direction is emitted in a greatest amount from the liquid crystal cell towards the second absorptive polarizer, the first light being one that is reflected by the reflective polarizer and transmitted through the second absorptive polarizer, the liquid crystal cell, and the first absorptive polarizer, the second light being one that is incident on the first absorptive polarizer.

11. A liquid crystal device in accordance with claim 7, the display device further comprising:

a backlight that is disposed opposite to the second absorptive polarizer across the reflective polarizer,

wherein light emitted from the backlight is adjusted to have a color other than white, in order to cause color of a first light to be close to color of a second light, the first light being one that is emitted from the backlight and transmitted through the reflective polarizer, the second absorptive polarizer, the liquid crystal cell, and the first absorptive polarizer, the second light being one that comes from the outside and is transmitted through the first absorptive polarizer, the liquid crystal cell, and the second absorptive polarizer, subsequently reflected by the reflective polarizer, then transmitted through the second absorptive polarizer, the liquid crystal cell, and the first absorptive polarizer.

12. An electronic apparatus in accordance with claim 11, wherein the backlight comprises:

a light source; and

a color filter that adjusts color of light emitted from the light source.