Patent ID: 8653735

Claim:
A backlight module applied to a liquid crystal display device, the back light module comprising: a control circuit for outputting a driving signal according to an analog dimming signal or a digital dimming signal; a driving circuit, electrically coupled to the control circuit, for receiving the driving signal and thereby outputting a lamp voltage according to the received driving signal; a fluorescent lamp set, electrically coupled to the driving circuit and comprising a plurality of fluorescent lamps, for receiving the lamp voltage and thereby producing a lamp current; a lamp feedback circuit, electrically coupled to the driving circuit, for obtaining the lamp voltage and outputting a feedback signal according to the obtained lamp voltage; and a dynamic protection circuit, electrically coupled between the lamp feedback circuit and the control circuit, for dynamically adjusting a protection command signal according to the analog dimming signal or the digital dimming signal, comparing the protection command signal and the feedback signal, and thereby generating a comparing result signal to the control circuit, wherein, the dynamic protection circuit comprises: a direct current level adjustment circuit, for receiving the analog dimming signal and thereby adjusting the protection command signal; and a comparing circuit, electrically coupled to the direct current level adjustment circuit, for receiving the adjusted protection command signal and the feedback signal and thereby outputting the comparing result signal.