Light source, display device, portable terminal device, and ray direction switching element

• US 7,929,077 B2
• Filed: 05/06/2010
• Issued: 04/19/2011
• Est. Priority Date: 05/24/2004
• Status: Active Grant

• Current Assignee: NLT Technologies, Ltd.
• Original Assignee: NEC Corporation
• Inventors: Uehara, Shinichi, Okumura, Fujio, Sumiyoshi, Ken, Suzuki, Teruaki
• Primary Examiner(s): QI, ZHI QIANG
• Application Number:
  US12/662,849
• Publication Number:
  US 20100220263A1
• Time in Patent Office: 348 Days
• Field of Search: 349/61, 349/62, 349/66
• US Class Current: 349/61
• CPC Class Codes: G02F 1/1323 Arrangements for providing a switchable viewing angle
• CPC Class Codes: G02F 1/133524 Light-guides, e.g. fibre-optic bundles, louvered or jalousie light-guides
• CPC Class Codes: G02F 1/133606 including a specially adapted diffusing, scattering or light controlling members
• CPC Class Codes: G02F 1/13476 in which at least one liquid crystal cell or layer assumes a scattering state

Abstract

A planar light source includes a backlight that emits light in a planar shape, a ray direction regulating element that regulates a direction of light made incident from the backlight and emits the light, whereby a directivity of the light is improved, and in which a transparent area for transmitting light and an absorption area for absorbing light are formed, and a transparent and scattering switching element that is switchable between a state in which light which is transmitted by the ray direction regulating element and made incident on the switching element is transmitted and a state in which the light is scattered. The transparent areas are formed in a shape of a matrix including a plurality of rows and a plurality of columns, the transparent and absorption areas are formed alternately, and the absorption area is formed so that the transparent areas are separated.

Claims

1. A planar light source comprising:

a backlight that emits light in a planar shape;

a ray direction regulating element that regulates a direction of light made incident from the backlight and emits the light, whereby a directivity of the light is improved, and in which a transparent area for transmitting light and an absorption area for absorbing light are formed; and

a transparent and scattering switching element that is switchable between a state in which light which is transmitted by the ray direction regulating element and made incident on the switching element is transmitted and a state in which the light is scattered, wherein

the transparent areas are formed in a shape of a matrix comprising a plurality of rows and a plurality of columns;

the transparent and absorption areas are formed alternately; and

the absorption area is formed so that the transparent areas are separated.

2. The planar light source according to claim 1, wherein an amount of light of the backlight and the transparent and scattering states of the transparent and scattering switching element can be set independently.

3. A display device that has the planar light source according to claim 1.

4. A portable terminal device that has the planar light source according to claim 1.

5. The portable terminal device according to claim 4, wherein the portable terminal device comprises one of a cellular phone, a personal digital assistant, a game machine, a digital camera, and a digital video camera.

6. The portable terminal device according to claim 4, further comprising:

adjusting means for changing an amount of the backlight and the transparent and scattering states of the transparent and scattering switching element independently from each other.

7. The portable terminal device according to claim 6, further comprising:

electric power accumulating means for accumulating electric power; and

residual amount detecting means for detecting electric power accumulated in the electric power accumulating means; and

control means for automatically changing an amount of light of the backlight and the transparent and scattering states of the transparent and scattering switching element on the basis of detected residual amount information.

8. The planar light source according to claim 1, wherein the transparent area of the ray direction regulating element comprises one of a circular transparent area and a quadrangle transparent area.

9. The planar light source according to claim 1, wherein the ray direction regulating element comprises a louver.

10. The planar light source according to claim 1, wherein the transparent area of the ray direction regulating element comprises plural transparent areas formed in rows and columns in the absorption area and surrounded by the absorption area.

11. The planar light source according to claim 1, wherein the ray direction of light incident on the ray direction regulating element is regulated in various directions.

12. The planar light source according to claim 1, wherein the light emitted by the backlight has an elliptical distribution, and light spreading in a longitudinal direction of the elliptical distribution is absorbed by the absorption area of the ray direction regulating element.

13. A display device comprising:

a backlight that emits light in a planar shape;

a ray direction regulating element that regulates a direction of light made incident from the backlight and emits the light, whereby a directivity of the light is improved, and in which a transparent area for transmitting light and an absorption area for absorbing light are formed;

a transparent and scattering switching element that is switchable between a state in which light which is transmitted by the ray direction regulating element and made incident on the switching element is transmitted and a state in which the light is scattered; and

a liquid crystal panel that displays an image with light made incident from the transparent and scattering switching element, wherein,

the transparent areas are formed in a shape of a matrix comprising a plurality of rows and a plurality of columns;

the transparent and absorption areas are formed alternately; and

the absorption area is formed so that the transparent areas are separated.

14. The display device according to claim 13, wherein, when the transparent and scattering switching element is in the scattering state, the display device adjusts brightness of an image displayed on the display panel by setting an amount of light of the backlight larger than that in the case in which the transparent and scattering switching element is in the transparent state.

15. The display device according to claim 14, wherein the backlight comprises a white light source.

16. The display device according to claim 15, wherein the white light source includes a blue LED and a yellow phosphor to adjust an amount of light with pulse modulation.

17. The display device according to claim 14, wherein the backlight includes a red light source, a green light source, and a blue light source and the red tight source, the green light source, and the blue light source are adjusted independently from each other.

18. The display device according to claim 13, wherein the transparent and scattering switching element includes flat electrodes which are formed in a line shape or a block shape and perform switching of transparent and scattering of the transparent and scattering switching element partially on the basis of image information displayed on the display panel.

19. The display device according to claim 13, wherein the display panel comprises a liquid crystal panel and the liquid crystal display panel comprises a panel of one of a lateral electric field mode, a multi-domain vertical orientation mode, and a film compensation TN mode.

20. A light regulator for planar light source having a backlight that emits light in a planar shape, the regulator comprising:

a ray direction regulating element that regulates a direction of light made incident from the backlight and emits the light, whereby a directivity of the light is improved, and in which a transparent area for transmitting light and an absorption area for absorbing light are formed; and

a transparent and scattering switching element that is switchable between a state in which light which is transmitted by the ray direction regulating element and made incident on the switching element is transmitted and a state in which the light is scattered, wherein

the transparent areas are formed in a shape of a matrix comprising a plurality of rows and a plurality of columns;

the transparent and absorption areas are formed alternately; and

the absorption area is formed so that the transparent areas are separated.

21. The light regulator of claim 20, wherein an amount of light emitted by the backlight and an amount of light transmitted by the light regulator are independently settable.

22. The light regulator of claim 21, further comprising:

a substrate, the ray direction regulating element being formed on the substrate and the transparent and scattering switching element being formed on the ray direction regulating element.