Backlight system and LCD using the same

• US 20060232995A1
• Filed: 04/19/2005
• Published: 10/19/2006
• Est. Priority Date: 01/28/2005
• Status: Active Grant

• Current Assignee: AU Optronics Corporation
• Original Assignee: AU Optronics Corporation
• Inventors: Wu, Meng-Chai, Hsieh, Chin-Kun
• Granted Patent: US 7,575,357 B2
• Time in Patent Office: Days
• US Class Current: 362/613
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133604 with lamps
• CPC Class Codes: Y10S 362/802 Position or condition responsive switch

Abstract

A backlight system and an LCD using the same are provided. The present backlight system is equipped with a light-source driving module and several light sources of different optimum working temperature ranges. Hence, according to the environmental temperature, appropriate light source(s) will be driven by the light-source driving module to maintain a constant light output of the backlight system.

Claims

1. A backlight system, comprising:

a light guide plate having an incidence surface;

a first light source disposed adjacent to said incidence surface;

a second light source disposed adjacent to said incidence surface; and

a light-source driving module, wherein said first light source and said second light source are driven selectively by said light-source driving module according to an environmental temperature.

2. The system of claim 1, wherein said first light source comprises an light emitting diode (LED) array and said second light source comprises a cold cathode fluorescent lamp (CCFL).

3. The system of claim 2, wherein said first light source is disposed over said second light source.

4. The system of claim 2, wherein said first light source is disposed beneath said second light source.

5. The system of claim 1, wherein said first light source has an operation temperature less than 40°

C.

6. The system of claim 1, wherein said second light source has an operation temperature equal to or higher than 40°

C.

7. The system of claim 1, wherein said light-source driving module comprises:

a temperature sensor for detecting the environmental temperature and providing a temperature parameter; and

a driving device for selectively driving said first light source and said second light source according to the temperature parameter.

8. The system of claim 7, wherein said driving device comprises an automatic switch device for providing a driving signal according to said temperature parameter.

9. The system of claim 8, further comprising a manual switch device for controlling the light-source driving module.

10. The system of claim 1, wherein said light-source driving module is configured to drive both of said first light source and said second light source in response to the environmental temperature substantially between 20°

C. and 40°

C.

11. The system of claim 1, wherein said light-source driving module is configured to drive said first light source in response to the environmental temperature substantially lower than 20°

C.

12. The system of claim 1, wherein said light-source driving module is configured to drive said second light source in response to the environmental temperature substantially higher than 40°

C.

13. The system of claim 1, further comprising a manual switch device for controlling the light-source driving module.

14. The system of claim 1, wherein said backlight system is an edge-lighting light source module.

15. The system of claim 1, further comprising a third light source disposed adjacent to said incidence surface, wherein said first light source, said second light source, and said third light source are driven selectively by said light-source driving module according to the environmental temperature.

16. The system of claim 15, wherein said first light source comprises an LED array, and said second light source and said third light source comprise CCFLs.

17. The system of claim 16, wherein said light-source driving module is configured to drive said first light source in response to the environmental temperature substantially lower than 50°

C., said light-source driving module is configured to drive said second light source in response to the environmental temperature substantially between 50°

C. and 80°

C., and said light-source driving module is configured to drive said third light source in response to the environmental temperature substantially higher than 80°

C.

18. The system of claim 1, further comprising a reflector, wherein said first light source is disposed between said light guide plate and said reflector.

19. The system of claim 18, wherein said second light source is disposed between said light guide plate and said reflector.

20. A liquid crystal display (LCD), comprising:

an LCD panel; and

a backlight system disposed adjacent to said LCD panel, wherein said backlight system comprises;

a light guide plate having an incidence surface;

a first light source disposed adjacent to said incidence surface;

a second light source disposed adjacent to said incidence surface; and

a light-source driving module wherein said first light source and said second light source are driven selectively by said light-source driving module according to an environmental temperature.

21. The LCD of claim 20, wherein said first light source is disposed over said second light source.