Patent ID: 7471427

Claim:
A warm-up circuit for CCFLs disposed in a scanner for controlling the brightness of a CCFL according to a reference voltage, said warm-up circuit comprising: an inverter connected to said CCFL and providing a drive power to said CCFL; and a PWM control unit connected to said inverter and outputting a first control signal to said inverter in a warm-up time and outputting a second control signal to said inverter to control said inverter supplying power to said CCFL in a scan time; wherein said inverter includes: a transformer connected to said CCFL via a secondary side coil for conversion of said drive power; and at least a transfer switch connected to said PWM control unit, said reference voltage and a primary side coil of said transformer, said transfer switch being controlled by said first control signal and said second control signal in order to perform on/off switching actions and transfer said reference voltage to the primary side coil of said transformer in an alternating way.