Patent ID: 7728533
Filing Date: 2010-06-01
Classification: H05B,Y02B

Abstract:
1. A backlight control circuit comprising: at least two load circuits, each of the load circuits comprising a backlight and a backlight inspecting circuit connected in series, wherein the backlight inspecting circuit comprises an output end; a pulse width modulation integrated circuit (PWM IC) comprising a current sampling pin; a switching circuit comprising a first transistor, a source electrode of the first transistor configured to be connected to ground, a drain electrode of the first transistor being connected to the current sampling pin of the PWM IC, a gate electrode of the first transistor configured to be connected to a direct current (DC) power supply; and an input circuit comprising at least two first diodes, at least two input resistors, at least two first filter capacitors, a first bias resistor, a second transistor, and a pink-to-pink detector circuit, the pink-to-pink detector circuit comprising a second diode, a second bias resistor, and a second filter capacitor; wherein positive terminals of the first diodes are respectively connected to a positive terminal of the second diode, a negative terminal of each of the first diodes is configured to be connected to ground via a respective one of the first filter capacitors and is connected to the output end of a respective one of the load circuits via a respective one of the input resistors, a positive terminal of the second diode is configured to be connected to the DC power supply via the first bias resistor, a negative terminal of the second diode is connected to a gate electrode of the second transistor and is configured to be connected to ground respectively via the second filter capacitor and the second bias resistor, a source electrode of the second transistor is configured to be connected to ground, and a drain electrode of the second transistor is connected to the gate electrode of the first transistor.