Viewing angle control element, display device, and electronic apparatus

• US 20040252258A1
• Filed: 04/27/2004
• Published: 12/16/2004
• Est. Priority Date: 05/09/2003
• Status: Active Grant

• Current Assignee: BOE Technology Group Co., Ltd.
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Matsushima, Toshiharu
• Granted Patent: US 7,400,367 B2
• Time in Patent Office: Days
• US Class Current: 349/96
• CPC Class Codes: G02F 1/1323 Arrangements for providing a switchable viewing angle
• CPC Class Codes: G02F 1/1347 Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells
• CPC Class Codes: G02F 1/13471 in which all the liquid crystal cells or layers remain transparent, e.g. FLC, ECB, DAP, HAN, TN, STN, SBE-LC cells G02F1/13475 takes precedence

Abstract

The invention provides a viewing angle control element capable of realizing high information concealment without damaging brightness of transmitted light and dynamically changing a viewing angle in accordance with need or no need of information concealment. The viewing angle control element according to the invention can include liquid crystal twist-aligned by approximately 180°, and have a liquid crystal layer being electrically controllable and a pair of polarizing layers provided at both sides of the liquid crystal layer. Optical axes of both polarizing layers can be arranged to be substantially parallel to each other, and liquid crystal molecules of the liquid crystal layer adjacent to the polarizing layers can be aligned to be substantially parallel to the optical axes of the polarizing layers.

Claims

1. A viewing angle control element, comprising:

a liquid crystal layer that is electrically controllable; and

a pair of polarizing layers provided at both sides of the liquid crystal layer.

2. The viewing angle control element according to claim 1, optical axes of the pair of polarizing layers being arranged to be substantially parallel to each other.

3. The viewing angle control element according to claim 2,

the liquid crystal layer including liquid crystal twist-aligned by approximately 180°

, and

liquid crystal molecules adjacent to the polarizing layers being aligned to be substantially parallel to the optical axes of the polarizing layers.

4. The viewing angle control element according to claim 2,

an alignment axis of the liquid crystal layer and absorption axes of the polarizing layers being arranged to be substantially perpendicular to each other.

5. The viewing angle control element according to claim 2,

an alignment axis of the liquid crystal layer and absorption axes of the polarizing layers being arranged to be substantially parallel to each other.

6. The viewing angle control element according to claim 1,

product Δ

nd of the refractive-index anisotropy Δ

n of the liquid crystal layer and a thickness d of the liquid crystal layer being equal to or greater than 1.0 μ

m.

7. The viewing angle control element according to claim 1,

product Δ

nd of the refractive-index anisotropy Δ

n of the liquid crystal layer and a thickness d of the liquid crystal layer being equal to or less than 8.0 μ

m.

8. The viewing angle control element according to claim 1,

product Δ

nd of the refractive-index anisotropy Δ

n of the liquid crystal layer and a thickness d of the liquid crystal layer being equal to or greater than 2.0 μ

m, and equal to or less than 5.0 μ

m.

9. The viewing angle control element according to claim 1,

a phase difference layer being provided between the pair of polarizing layers.

10. The viewing angle control element according to claim 9,

the phase difference layer being provided at both sides of the liquid crystal layer.

11. The viewing angle control element according to claim 9,

the phase difference layer having an optical characteristic of giving a phase difference to a component of light transmitted through the phase difference layer in a direction of thickness.

12. A display device, comprising the viewing angle control element according to claim 1 and a display element,

the viewing angle control element adjusting the viewing angle of the display element.

13. A display device according to claim 12,

the display element including a liquid crystal display element, and the viewing angle control element being provided on a front surface or a back surface of the liquid crystal display element.

14. A display device according to claim 13,

the polarizing layer of the viewing angle control element on the liquid crystal display element side functioning as a polarizing layer of the liquid crystal display element.

15. A display device according to claim 13,

an optical rotation device that adjusts a deviation between an optical axis of a polarizing layer provided on a viewing angle control element forming surface of the liquid crystal display element and the optical axes of the polarizing layers of the viewing angle control element being provided between the liquid crystal display element and the viewing angle control element.

16. A display device according to claim 15,

the optical rotation device being a half-wave plate.

17. A display device according to claim 15,

the optical rotation device having twist-aligned liquid crystal.

18. A display device according to claim 12,

the display element including an EL display element, a circularly polarizing layer being provided between the EL display element and the viewing angle control element, and the polarizing layer of the viewing angle control element on an EL display element side constituting a part of the circularly polarizing layer.

19. An electronic apparatus, comprising the viewing angle control element according to claim 1.

20. An electronic apparatus, comprising the display device according to claim 12.