Patent ID: 7330003

Claim:
A backlight control circuit comprising: a first load circuit comprising a first backlight and a first backlight inspecting circuit connected in series, the first backlight inspecting circuit comprising a first output end; a second load circuit comprising a second backlight and a second backlight inspecting circuit connected in series, the second backlight inspecting circuit comprising a second output end; a pulse width modulation integrated circuit (PWM IC) comprising a current sampling pin; a switching circuit comprising a first transistor, a second transistor, a current limiting resistor, and a bias resistor, the first transistor comprising an emitter electrode connected to ground, a collector electrode connected to the sampling pin of the PWM IC, and a base electrode, the second transistor comprising an emitter electrode connected to ground, a collector electrode connected to the base electrode of the first transistor, and a base electrode connected to the ground via the bias resistor; a first input circuit comprising: a first resistor; a first capacitor; a first voltage division resistor; and a first diode comprising a positive terminal connected to the first output end of the first backlight inspecting circuit, and a negative terminal connected to ground via the first resistor and the first capacitor respectively, the negative terminal also connected to the base electrode of the second transistor via the first voltage division resistor; and a second input circuit comprising a first input resistor, the second output end of the second backlight inspecting circuit connected to the current sampling pin of the PWM IC via the first input resistor.