Backlight driving apparatus of liquid crystal display and method for driving backlight driving apparatus

• US 20070285029A1
• Filed: 12/28/2006
• Published: 12/13/2007
• Est. Priority Date: 06/07/2006
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Philips LCD Company Limited (LG Display Co., Ltd.)
• Inventors: Kim, Byoung Chul
• Granted Patent: US 7,589,479 B2
• Time in Patent Office: Days
• US Class Current: 315/246
• CPC Class Codes: H05B 41/2853 against abnormal power supply conditions

Abstract

A backlight driving apparatus for a liquid crystal display device includes a light source, an AC driver for supplying a high voltage AC power to turn on the light source, and a protection circuit electrically connected to the AC driver responsive to an input voltage lower than a reference voltage for stopping the driving of the AC driver.

Claims

1. A backlight driving apparatus for a liquid crystal display device, comprising:

a light source;

an AC driver for supplying a high voltage AC power to turn on the light source; and

a protection circuit electrically connected to the AC driver responsive to an input voltage lower than a reference voltage for stopping the driving of the AC driver.

2. The backlight driving apparatus of claim 1, the protection circuit comprising:

a reference voltage setting unit for setting a level of the reference voltage;

one or more resistors for dividing the input voltage applied to the AC driver to form a comparison voltage; and

a comparator having two input terminals connected to an output terminal of the reference voltage setting unit and the one or more resistors, respectively, wherein the comparator compares the reference voltage and the comparison voltage received via the one or more resistors and outputs a control voltage for the driving of the AC driver.

3. The backlight driving apparatus of claim 2, wherein the reference voltage setting unit includes a zener diode.

4. The backlight driving apparatus of claim 2, wherein the comparison voltage is higher than the reference voltage and the comparator outputs the control voltage as a high level and drives the AC driver in a normal state.

5. The backlight driving apparatus of claim 4, wherein the control voltage is higher than the comparison voltage.

6. The backlight driving apparatus of claim 2, wherein the comparator outputs the control voltage as a low level and shuts down the AC driver when the comparison voltage is lower than the reference voltage.

7. The backlight driving apparatus of claim 6, wherein the control voltage is lower than the comparison voltage.

8. The backlight driving apparatus of claim 6, wherein the control voltage is a ground voltage.

9. The backlight driving apparatus of claim 2, wherein the comparator is an operational amplifier.

10. The backlight driving apparatus of claim 1, wherein the AC driver comprising:

a DC/AC converter for converting a DC input voltage into an AC voltage; and

a transformer for boosting the AC voltage converted through the DC/AC converter to a predetermined level.

11. The backlight driving apparatus of claim 1, wherein the light source includes a cold cathode fluorescent lamp.

12. The backlight driving apparatus of claim 1, wherein the light source includes an external electrode fluorescent lamp.

13. A backlight driving apparatus for a liquid crystal display, comprising:

a light-emitting diode;

a DC driver for supplying a high voltage DC power to turn on the light-emitting diode; and

a protection circuit electrically connected to the DC driver responsive to an input voltage lower than a reference voltage for stopping the driving of the DC driver.

14. The backlight driving apparatus of claim 13, wherein the protection circuit comprising:

a reference voltage setting unit for setting a level of the reference voltage;

one or more resistors for dividing the input voltage applied to the DC driver to form a comparison voltage; and

a comparator having two input terminals connected to an output terminal of the reference voltage setting unit and the one or more resistors, respectively, wherein the comparator compares the reference voltage and the comparison voltage received via the one or more resistors and outputs a control voltage for the driving of the DC driver.

15. The backlight driving apparatus of claim 14, wherein the reference voltage setting unit includes a zener diode.

16. The backlight driving apparatus of claim 14, wherein the comparison voltage is higher than the reference voltage and the comparator outputs the control voltage as a high level and drives the DC driver in a normal state.

17. The backlight driving apparatus of claim 16, wherein the control voltage is higher than the comparison voltage.

18. The backlight driving apparatus of claim 14, wherein the comparator outputs the control voltage as a low level and shuts down the DC driver when the comparison voltage is lower than the reference voltage.

19. The backlight driving apparatus of claim 18, wherein the control voltage is lower than the comparison voltage.

20. The backlight driving apparatus of claim 18, wherein the control voltage is a ground voltage.

21. The backlight driving apparatus of claim 14, wherein the comparator includes an operational amplifier.

22. The backlight driving apparatus of claim 14, the DC driver comprising:

a pulse width modulation signal providing unit for transforming a DC input voltage into a pulse width modulation signal and outputting the transformed pulse width modulation signal, and

a static voltage providing unit for transforming the transformed pulse width modulation signal into a constant level and providing the transformed signal.

23. A method for driving a backlight driving apparatus of a liquid crystal display, comprising:

providing an input voltage to a driver for supplying a high voltage driving power to a light source;

setting a reference voltage with a zener diode;

dividing the input voltage to form a comparison voltage;

comparing the comparison voltage and the reference voltage; and

driving or shutting down the driver by outputting a control voltage to control the operation of the driver after the comparison step.

24. The method of claim 23, wherein the comparison voltage is higher than the reference voltage and the control voltage is outputted as a high level so that the driver is driven in a normal state.

25. The method of claim 24, wherein the control voltage is higher than the comparison voltage.

26. The method of claim 23, wherein the control voltage is output as a low level so that the driver is shut down when the comparison voltage is lower than the reference voltage.

27. The method of claim 26, wherein the control voltage is lower than the comparison voltage.

28. The method of claim 27, wherein the control voltage is a ground voltage.