Patent ID: 7800318
Filing Date: 2010-09-21
Classification: H05B

Abstract:
1. A power supply device for a backlight control of the LCD panel, capable of driving a plurality of cold cathode fluorescence lamps (CCFL), comprising: a switching electronic ballast circuit, utilizing a primary sine wave voltage produced by a switching modulation circuit, wherein the primary sine wave voltage is transferred via a transformer to output a secondary sine wave voltage; an impedance matching device at positive end, installed in between positive ends of the plurality of cold cathode fluorescence lamps and a positive end of a secondary winding of the transformer in order to balance the CCFL current; a CCFL abnormal detective circuit, providing a detective unit respectively for each of the plurality of CCFL, wherein the detective unit comprises a voltage detective capacitor and a delay capacitor, every voltage detective capacitor is connected to a positive end of the corresponding CCFL to determine a positive end voltage, one end of the delay capacitor is connected to ground so that it can be charged or discharged through the positive end voltage, a first optical coupler of the CCFL abnormal detective circuit outputs a detective signal according to the positive end voltage to switch on or off the switching electronic ballast circuit; an adjusting and enabling control device, producing and outputting an enabling signal to the switching electronic ballast circuit according to a low frequency signal for adjusting pulse wave width in order to control the operation timing of the switching electronic ballast circuit; and an auxiliary power source circuit, providing a stable direct current voltage to the CCFL abnormal detective circuit.