| 摘要 |
A back lighting source module for a liquid crystal display comprises a pulse width modulation (PWM) controller for providing a pulse width signal to control output current of a lighting element. A half bridge converter includes two power transistors connected in series. An output is formed in a middle between the two power transistors. The output is controllable by the signal from the PWM controller to perform alternating opening and closing. A resonance circuit generates a sine-wave voltage to empower the lighting element. A feedback circuit includes a resistor. When a load varies, a voltage signal generated between two ends of the resistor of the feedback circuit timely changes a conductive time of the power transistors of the half bridge converter to complete regulation of current passing through the lighting element.
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