Planar light source device, liquid crystal display apparatus, and display apparatus

• US 20040119908A1
• Filed: 11/05/2003
• Published: 06/24/2004
• Est. Priority Date: 12/18/2002
• Status: Active Grant

• Current Assignee: Trivale Technologies, LLC (Vector Capital Corporation)
• Original Assignee: Advanced Display Technologies
• Inventors: Sakai, Seiji
• Granted Patent: US 6,964,500 B2
• Time in Patent Office: Days
• US Class Current: 349/65
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: H01H 2219/056 Diffuser; Uneven surface

Abstract

A liquid crystal display apparatus has R, G, and B LEDs and a light guide plate for guiding and diffusing the light entering through an incident surface evenly over the plate. The bottom surface of the light guide plate has a diffusion portion where microdot pattern is printed to diffuse incident light. The liquid crystal display apparatus also has an optical sensor for receiving the light exiting from the light guide plate through a side surface, and a light-shielding member mounted in front of the optical sensor. The light-shielding member has pinholes to block the light incident on the optical sensor in the direction from the incident surface to the opposite surface at an incidence angle greater than a given angle. The luminance of the LEDs is controlled based on the light detected by the optical sensor.

Claims

1. A planar light source device comprising:

a plurality of light sources;

a light guide plate for guiding light entering through an incident surface from the plurality of light sources evenly over the light guide plate;

a diffusion portion for diffusing incident light, formed on the light guide plate;

an optical sensor for receiving light exiting from the light guide plate through a side surface thereof; and

a light-shielding member mounted in front of the optical sensor, for blocking light incident on a light-receiving surface of the optical sensor at an incident angle greater than a given angle;

wherein luminance of each of the plurality of light sources is controlled based on light detected by the optical sensor.

2. A planar light source device according to claim 1, comprising:

a plurality of light sources for emitting different colors of light; and

a plurality of optical sensors for detecting different colors of light,

wherein luminance of each of the plurality of light sources for emitting different colors of light is controlled based on light detected by each of the plurality of optical sensors.

3. A planar light source device according to claim 1, wherein the light-shielding member comprises black resin having a pinhole.

4. A planar light source device according to claim 2, wherein the light-shielding member comprises black resin having a pinhole.

5. A planar light source device according to claim 1, further comprising:

an infrared filter for blocking infrared light, placed between the optical sensor and the light-shielding member.

6. A planar light source device according to claim 2, further comprising:

an infrared filter for blocking infrared light, placed between the optical sensor and the light-shielding member.

7. A planar light source device according to claim 3, further comprising:

an infrared filter for blocking infrared light, placed between the optical sensor and the light-shielding member.

8. A planar light source device according to claim 1, wherein the plurality of light sources comprise light-emitting diodes.

9. A planar light source device according to claim 2, wherein the plurality of light sources comprise light-emitting diodes.

10. A planar light source device according to claim 3, wherein the plurality of light sources comprise light-emitting diodes.

11. A planar light source device according to claim 5, wherein the plurality of light sources comprise light-emitting diodes.

12. A liquid crystal display apparatus comprising:

a planar light source device according to claim 1;

and

a liquid crystal panel mounted above the planar light source device, comprising two substrates with a liquid crystal layer interposed therebetween.

13. A liquid crystal display apparatus comprising:

a planar light source device according to claim 2;

and

a liquid crystal panel mounted above the planar light source device, comprising two substrates with a liquid crystal layer interposed therebetween.

14. A liquid crystal display apparatus comprising:

a planar light source device according to claim 3;

and

a liquid crystal panel mounted above the planar light source device, comprising two substrates with a liquid crystal layer interposed therebetween.

15. A liquid crystal display apparatus comprising:

a planar light source device according to claim 5;

and

a liquid crystal panel mounted above the planar light source device, comprising two substrates with a liquid crystal layer interposed therebetween.

16. A liquid crystal display apparatus comprising:

a planar light source device according to claim 8;

and

a liquid crystal panel mounted above the planar light source device, comprising two substrates with a liquid crystal layer interposed therebetween.

17. A display apparatus comprising:

a plurality of light sources;

a light guide plate for guiding light entering through an incident surface from the plurality of light sources evenly over the light guide plate;

a diffusion portion for diffusing incident light, formed on the light guide plate;

an optical sensor mounted on a side surface of the light guide plate which is adjacent to the incident surface on which light from the plurality of light sources is incident;

a light-shielding member mounted in front of the optical sensor, for blocking light incident on a light-receiving surface of the optical sensor at an incidence angle greater than a given angle; and

a display panel mounted above the light guide plate,

wherein luminance of each of the plurality of light sources is controlled based on light detected by the optical sensor.