Backlight unit and driving method thereof, and liquid crystal display device having the backlight unit

• US 7,614,778 B2
• Filed: 12/07/2006
• Issued: 11/10/2009
• Est. Priority Date: 06/30/2006
• Status: Expired due to Fees

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Ahn, Byeong Hyeon
• Primary Examiner(s): O'Shea; Sandra L
• Assistant Examiner(s): Dunwiddie; Meghan K
• Application Number:
  US11/635,363
• Publication Number:
  US 20080002424A1
• Time in Patent Office: 1,069 Days
• Field of Search: 362/555, 362/561, 362/612, 362/630, 362/631
• US Class Current: 362/631
• CPC Class Codes: G02B 6/0011 the light guides being planar or of plate-like form
• CPC Class Codes: G02B 6/0073 Light emitting diode [LED]
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2360/141 the light conveying information used for selecting or modulating the light emitting or modulating element
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336

Abstract

A liquid crystal display device, backlight unit, and method of driving a backlight unit are provided. The backlight includes a lamp and an inverter that is operative to supply a driving voltage to the lamp. An illuminance correction system is operative to sense a surrounding luminance of the lamp and to illuminate a predetermined amount of light.

Claims

1. A backlight unit comprising:

a lamp;

an inverter that is operative to supply a driving voltage to the lamp; and

an illuminance correction system that is operative to sense a surrounding luminance of the lamp and to illuminate a predetermined amount of light, the illuminance correction system comprising

a light sensor, a light emitting device disposed around the lamp, and a controller that controls the light sensor and the light emitting device,

wherein the light sensor senses the illuminance around the lamp,

wherein the light emitting device emits light to secure an environment for the stable driving of the lamp and

wherein the controller stops driving the light emitting device, when the lamp is driven by the inverter.

2. The backlight unit according to claim 1, wherein the light sensor is disposed in close proximity of the lamp.

3. The backlight unit according to claim 1, wherein the light sensor comprises a photodiode that is operative to sense light or a thin film transistor.

4. The backlight unit according to claim 1, wherein the light emitting device is disposed in proximity of the lamp.

5. The backlight unit according to claim 1, wherein the light emitting device comprises a tight emitting diode (LED).

6. The backlight unit according to claim 1, wherein the controller has a preset reference illuminance.

7. The backlight unit according to claim 6, wherein the present reference illuminance is set to 1 lx.

8. The backlight unit according to claim 6, wherein the controller is operatively coupled to compare the sensed surrounding illuminance with the reference illuminance.

9. The backlight unit according to claim 8, wherein the controller is operative to generate an ON control signal when the sensed surrounding illuminance is smaller than the reference illuminance, and generate an OFF control signal when the sensed surrounding illuminance is equal to or higher than the reference illuminance.

10. A liquid crystal display device comprising:

an illuminance correction system that is operative to sense a surrounding illuminance of a lamp and emit a predetermined amount of light from the lamp; and

a liquid crystal display panel displaying an image using the light emitted from the lamp,

wherein the illuminance correction system comprises a light sensor, a light emitting device disposed around the lamp, and a controller that controls the light sensor and the light emitting device,

wherein the light sensor senses the illuminance around the lamp,

wherein the light emitting device emits light to secure an environment for the stable driving of the lamp and

wherein the controller stops driving the light emitting device, when the lamp is driven by the inverter.

11. The liquid crystal display device according to claim 10, wherein the light sensor is disposed in close proximity of the lamp.

12. The liquid crystal display device according to claim 10, wherein the light sensor comprises a photodiode capable of sensing light or a thin film transistor.

13. The liquid crystal display device according to claim 10, wherein the light emitting device is disposed in close proximity of the lamp.

14. The liquid crystal display device according to claim 10, wherein the light emitting device comprises a light emitting diode (LED).

15. The liquid crystal display device according to claim 10, wherein the controller has a preset reference illuminance.

16. The liquid crystal display device according to claim 15, wherein the present reference illuminance is 1 lx.

17. The liquid crystal display device according to claim 16, wherein the controller is operatively coupled to compare the sensed surrounding illuminance with the reference illuminance.

18. The liquid crystal display device according to claim 17, wherein the controller is operative to generate an ON control signal when the sensed surrounding illuminance is smaller than the reference illuminance, and generate an OFF control signal when the sensed surrounding illuminance is equal to or higher than the reference illuminance.

19. A method of driving a backlight unit, the method comprising:

sensing a surrounding illuminance of a lamp;

comparing the surrounding illuminance with a preset reference illuminance;

generating an ON/OFF control signal of a light emitting device according to a result of the comparing; and

driving or stopping the light emitting device according to the ON/OFF control signal,

wherein the light emitting device is disposed around the lamp,

wherein the light emitting device emits light to secure an environment for the stable driving of the lamp and

wherein the controller stops driving the light emitting device when the lamp is driven by the inverter.

20. The method according to claim 19, wherein comparing the sensed surrounding iliuminance with the reference illuminance is performed by a controller.

21. The method according to claim 20, wherein the controller generates an ON control signal when the sensed surrounding illuminance is smaller than the reference illuminance, and generates OFF signal when the sensed surrounding illuminance is equal to or higher than the reference illuminance.

22. The method according to claim 19, wherein the controller generates an OFF control signal in a section where the lamp drives.

23. The method according to claim 19, wherein the preset reference illuminance is 1 lx.