Power supply for an LCD panel

• US 6,936,975 B2
• Filed: 04/15/2003
• Issued: 08/30/2005
• Est. Priority Date: 04/15/2003
• Status: Expired due to Fees

• Current Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Original Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Inventors: Lin, Yung-Lin, Liu, Da
• Primary Examiner(s): VU, DAVID HUNG
• Application Number:
  US10/414,374
• Publication Number:
  US 20040207339A1
• Time in Patent Office: 868 Days
• Field of Search: 315/224, 315/276, 315/277, 363/98, 363/17, 363/132
• US Class Current: 315/224
• CPC Class Codes: H05B 41/282 with semiconductor devices H05B41/2806, H05B41/288, H05B41/295 take precedence
• CPC Class Codes: H05B 41/2827 using specially adapted components in the load circuit, e.g. feed-back transformers, piezoelectric transformers; using specially adapted load circuit configurations
• CPC Class Codes: H05B 41/2828 using control circuits for the switching elements H05B41/2827 takes precedence
• CPC Class Codes: H05B 41/3921 with possibility of light intensity variations
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

A power supply system is provided for a multiple lamp LCD panel. In one aspect, the power supply includes a plurality of transformers for driving a plurality of respective CCFLs. The primary sides of each transformer are coupled in series to thereby reduce the stress on each transformer. For LCD panels that include longer CCFLs, a power supply is provided that includes a plurality of transformers for driving a plurality of respective CCFLs. The primary sides of each transformer are coupled in series and each lamp is coupled to two secondary sides of the transformers, thereby reducing the problems associated with longer CCFL tubes. In any of the embodiments, the power supply can be adapted to convert a high voltage DC signal to high voltage AC used to power the lamps.

Claims

1. A high voltage LCD power supply system, comprising:

an inverter controller operable to control a plurality of switches for converting a DC signal to an AC signal;

a plurality of transformers receiving said AC signal and each generating a high voltage sinusoidal signal, wherein each said transformer having a primary side and a secondary side and wherein each said primary side being coupled in series with each other across said AC signal; and

an LCD panel comprising a plurality of cold cathode fluorescent lamps, wherein one lamp is coupled between a positive polarity of a first secondary side and a negative polarity of a second secondary side; and

wherein a first feedback circuit is coupled to a negative polarity of said first secondary side and a second feedback circuit is coupled to a positive polarity of said second secondary side.

2. A power supply system as claimed in claim 1, wherein said switches being arranged in a full bridge circuit configuration, and said controller being adapted to control said full bridge circuit.

3. A power supply system as claimed in claim 1, wherein said switches being arranged in a half bridge circuit configuration, and said controller being adapted to control said half bridge circuit.

4. A power supply system as claimed in claim 1, wherein said switches being arranged in a class D circuit configuration, and said controller being adapted to control said class D circuit.

5. A power supply system as claimed in claim 1, wherein said first and second feedback circuits are capable of generating a current feedback signal indicative of current supplied to at least one said lamp, and said inverter controller adapted to receive said current feedback signal to adjust the current delivered to said at least one lamp.

6. A power supply system as claimed in claim 1, further comprising circuitry to generate a voltage feedback signal indicative of voltage supplied to at least one said lamp, and said inverter controller adapted to receive said voltage feedback signal to adjust the voltage delivered to said at least one lamp.