Patent ID: 6812916
Filing Date: 2004-11-02
Classification: H05B

Abstract:
A driving circuit for an LCD backlight, comprising:a DC/DC converter changing the level of an input DC power; an inverter converting the level-changed DC power into AC, boosting the converted AC power to higher voltage AC power, which is to be applied to a lamp, according to the ratio of a primary eside winding and a secondary side winding of a transformer; a feedback means sensing the AC current flowing in the lamp, feeding back the sensed current with electrical insulation between the primary side and the secondary side of the transformer, and flattening the fed back current wherein said feedback means comprise a photo coupler rectifying the AC current flowing in the lamp and feeding back the rectified current with electrical insulation; a rectifying element connected between the secondary winding and the lamp; and a DC filter flattening the output signal of the coupler; and a level controller comparing the flattened current with a reference signal, and providing the difference signal between the compared signals to the DC/DC converter which adjusts a target level to change according to the difference signal.