Power control system for LCD monitor

• US 20040164979A1
• Filed: 11/13/2003
• Published: 08/26/2004
• Est. Priority Date: 02/21/2003
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Lee, Sang Ho
• Granted Patent: US 7,400,315 B2
• Time in Patent Office: Days
• US Class Current: 345/212
• CPC Class Codes: H05B 41/2855 against abnormal lamp operating conditions
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

A power control system for an LCD monitor having an LCD panel includes a light source unit providing light to the LCD panel, a power supply unit generating a standard low DC current, and a high-voltage generator for converting the lower DC voltage to a relatively high voltage and supplying the high voltage to the light source. The power control system further includes a feedback control unit coupled to the power supply unit for interrupting the operation of the power supply unit when the converted high voltage is determined to be abnormal. The feedback control unit includes a cable, through which a voltage can be induced due to high voltage generated by the high-voltage generator, and a power supply control circuit capable of interrupting the operation of the power supply unit when the converted high voltage is determined to be abnormal by analyzing the induced current.

Claims

1. A power control system for a liquid crystal display (LCD) monitor having an LCD panel, the system comprising:

a light source unit providing light to the LCD panel;

a power supply unit generating a standard low direct current (DC) voltage;

a high-voltage generator coupled to the power supply unit for converting the low DC voltage to a relatively high voltage, the high-voltage generator supplying the high voltage to the light source unit; and

a feedback control unit coupled to the power supply unit for interrupting the operation of the power supply unit when the converted high voltage is determined to be abnormal.

2. The power control system of claim 1, wherein the feedback control unit determines whether the converted high voltage is abnormal or not by analyzing a voltage induced due to the high voltage generated by the high-voltage generator.

3. The power control system of claim 1, wherein the feedback control unit comprises a cable, through which a voltage is induced due to the high voltage generated by the high-voltage generator.

4. The power control system of claim 3, wherein the cable is a printed current board (PCB) pattern.

5. The power control system of claim 4, wherein the feedback control unit further comprises a power supply control circuit coupled to the PCB pattern and the power supply unit, the control circuit interrupting the operation of the power supply unit when the converted high voltage is determined to be abnormal by analyzing the induced voltage.

6. The power control system of claim 5, wherein the converted high voltage is determined to be abnormal when the induced voltage is suddenly increased or decreased or when there is no voltage induced through the PCB pattern at all.

7. The power control system of claim 5, wherein the converted high voltage is determined to be abnormal when the induced voltage is less than a predetermined voltage level.

8. The power control system of claim 5, wherein the power supply control circuit is integrated within the power supply unit.

9. The power control system of claim 8, wherein the power supply control circuit is a switching mode power supply (SMPS) control circuit.

10. The power control system of claim 5, wherein the feedback control unit further comprises:

a first capacitor coupled to the PCB pattern for performing alternating current (AC) coupling on the induced voltage;

an integration circuit coupled to the first capacitor for converting the AC-coupled voltage to a DC voltage by integration; and

a first diode coupled to the integration circuit and the power supply control circuit for outputting the integrated DC voltage to the power supply unit.

11. The power control system of claim 10, wherein the integration circuit comprises a resistor and a second capacitor.

12. The power control system of claim 10, further comprising a zener diode coupled to the first diode for cutting off the DC voltage being outputted through the first diode when it is higher than a breakdown voltage of the zener diode.

13. The power control system of claim 1, wherein the light source unit is a fluorescent lamp.

14. The power control system of claim 13, wherein the fluorescent lamp is a cold cathode fluorescent lamp (CCFL)

15. A power control system for a liquid crystal display (LCD) monitor having a LCD panel, the system comprising:

a light source unit providing light to the LCD panel;

a power supply unit generating a standard low DC voltage;

a direct current to direct current (DC/DC) converter coupled to the power supply unit for converting the standard DC voltage to a predetermined DC voltage;

a high-voltage generator coupled to the DC/DC converter for converting the predetermined DC voltage to a relatively high voltage, the high-voltage generator supplying the high voltage to the light source unit; and

a feedback control unit coupled to the power supply unit for interrupting the operation of the power supply unit when the converted high voltage is determined to be abnormal.

16. The power control system of claim 15, wherein the feedback control unit comprises:

a printed current board (PCB) pattern, through which a voltage is induced due to the high voltage generated by the high-voltage generator; and

a power supply control circuit coupled to the PCB pattern and the power supply unit, wherein the control circuit interrupts the operation of the power supply unit when the converted high voltage is determined to be abnormal by analyzing the induced voltage.

17. The power control system of claim 16, wherein the power supply control circuit is integrated within the power supply unit.

18. The power control system of claim 17, wherein the power supply control circuit is a switching mode power supply (SMPS) control circuit.

19. The power control system of claim 16, wherein the feedback control unit further comprises:

a first capacitor coupled to the PCP pattern for performing alternating current (AC) coupling on the induced voltage;

an integration circuit coupled to the first capacitor for converting the AC-coupled voltage to a DC voltage by integration; and

a first diode coupled to the integration circuit and the power supply control circuit for outputting the integrated DC voltage to the power supply unit.

20. The power control system of claim 19, wherein the integration circuit comprises a resistor and a second capacitor.

21. The power control system of claim 19, further comprising a zener diode coupled to the first diode for cutting off the DC voltage being outputted through the first diode when it is higher than a breakdown voltage of the zener diode.