Power control system for LCD monitor

• US 7,400,315 B2
• Filed: 11/13/2003
• Issued: 07/15/2008
• Est. Priority Date: 02/21/2003
• Status: Expired due to Fees

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Lee, Sang Ho
• Primary Examiner(s): Shalwala, Bipin
• Assistant Examiner(s): Holton, Steven E
• Application Number:
  US10/706,292
• Publication Number:
  US 20040164979A1
• Time in Patent Office: 1,706 Days
• Field of Search: 345/87, 345/102, 345211-213, 315/291
• US Class Current: 345/102
• 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 power control system comprising:

a light source unit for providing light to the LCD panel;

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

a high-voltage generator for outputting to the light source unit a high voltage based on the low DC voltage; and

a feedback control unit for detecting a voltage induced from the high voltage output, for determining based on a level of the induced voltage an abnormal condition of the high voltage output, and for inhibiting the output of the high-voltage generator during a time corresponding to the abnormal condition by suspending operation of said power supply unit during the time corresponding to the abnormal condition,

wherein said feedback control unit comprises a patterned conductor for conducting the induced voltage to said feedback control unit,

wherein the patterned conductor is configured to transmit the conductor voltage, the transmitted voltage representing the abnormal condition if a power surge exists in the high voltage output, representing the abnormal condition if there is no detection of induced voltage from voltage output, representing the abnormal condition if the level of the induced voltage indicates that the high voltage is less than a predetermined voltage level.

2. The power control system of claim 1, wherein the patterned conductor is a printed current board (PCB) pattern disposed electromagnetically proximate to an electric output of the high-voltage generator and to an electric input of the light source unit.

3. The power control system of claim 1, wherein the feedback control unit comprises:

a power supply control circuit for receiving the induced voltage and for suspending the operation of the power supply unit during the time corresponding to the abnormal condition.

4. The power control system of claim 3, wherein the power supply control circuit is integrated within the power supply unit.

5. The power control system of claim 3, wherein the feedback control unit further comprises:

a Zener diode for limiting the induced voltage received by the power supply control circuit.

6. The power control system of claim 4, wherein the power supply control circuit is a switching mode power supply (SMPS) control circuit.

7. The power control system of claim 1, wherein the feedback control unit comprises:

a coupling capacitor for alternating current (AC) coupling the induced voltage conducted by the patterned conductor;

an integration circuit for integrating the AC-coupled voltage, to output an integrated DC voltage; and

a rectifying diode for outputting the integrated DC voltage, the integrated DC voltage being used to determine the abnormal condition.

8. The power control system of claim 7, wherein the integration circuit comprises a series resistor and a shunt capacitor.

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

10. The power control system of claim 9, wherein the fluorescent lamp is a cold cathode fluorescent lamp (CCFL).

11. The power control system of claim 1, wherein the patterned conductor is electrically isolated from the high voltage output and has two ends, one end being connected to an input of the feedback control unit and the other end being grounded.

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

a light source unit for providing light to the LCD panel;

a power supply unit for generating a standard DC voltage;

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

a high-voltage generator for outputting to the light source unit a high voltage based on the predetermined DC voltage; and

a feedback control unit for detecting a voltage induced from the high voltage output, for determining based on a level of the induced voltage an abnormal condition of the high voltage output, and for inhibiting the output of the high-voltage generator during a time corresponding to the abnormal condition by suspending operation of said power supply unit during the time corresponding to the abnormal condition,

wherein said feedback control unit comprises a printed current board (PCB) pattern disposed electromagnetically proximate to an electrical output of the high-voltage generator and to an electrical input of the light source unit, for conducting the induced voltage to said feedback control unit,

wherein the PCB pattern is configured to transmit the conductor voltage, the transmitted voltage representing the abnormal condition if a power surge exists in the high voltage output, representing the abnormal condition if there is no detection of induced voltage from the high voltage output, and representing the abnormal condition if the level of the induced voltage indicates that the high voltage is less than a predetermined voltage level.

13. The power control system of claim 12, wherein the feedback control unit further comprises:

a power supply control circuit for receiving the induced voltage and for suspending the operation of the power supply unit during the time corresponding to the abnormal condition.

14. The power control system of claim 13, wherein the power supply control circuit is integrated within the power supply unit.

15. The power control system of claim 14, wherein the power supply control circuit is a switching mode power supply (SMPS) control circuit.

16. The power control system of claim 13, wherein the feedback control unit further comprises:

a coupling capacitor alternating current (AC) coupling the induced voltage conducted by the PCB pattern;

an integration circuit for integrating the AC-coupled voltage, to output an integrated DC voltage; and

a rectifying diode for outputting the integrated DC voltage to the power supply control circuit,

wherein the power supply control circuit uses the integrated DC voltage to determine the abnormal condition.

17. The power control system of claim 16, wherein the integration circuit comprises a series resistor and a shunt capacitor.

18. The power control system of claim 13, wherein the feedback control unit further comprises:

a Zener diode for limiting the induced voltage received by the power supply control circuit.

19. The power control system of claim 12, further comprising:

a main controller for generating a power control signal for controlling an on/off function of the power supply unit and for generating a brightness control signal for controlling brightness of the light source unit.

20. The power control system of claim 19, further comprising:

a brightness controller for controlling the predetermined DC voltage output from the DC/DC converter according to the brightness control signal received from the main controller.

21. A method for controlling power to a liquid crystal display (LCD) monitor having an LCD panel, the method comprising:

generating a low direct current (DC) voltage;

generating a high voltage based on the low DC voltage;

applying the generated high voltage to a light source unit for providing light to the LCD panel;

detecting a voltage induced from the high voltage applied to the light source unit;

determining, based on a level of the induced voltage, an abnormal condition of the high voltage output; and

inhibiting said high-voltage generation during a time corresponding to the abnormal condition by suspending said low DC voltage generating,

wherein the detected voltage is induced into a patterned conductor for conducting the induced voltage to a feedback control unit and wherein the patterned conductor is configured to transmit the conducted voltage, the transmitted voltage representing the abnormal condition if a power surge exists in the high voltage output, and representing the abnormal condition if the induced voltage indicates that the high voltage is less than a predetermined voltage level.