Patent ID: 7023142

Claim:
A method for modulating light of cold cathode fluorescent lamps (CCFLs) to module a luminosity of a CCFL by altering output voltage and output current of a piezoelectric transformer that actuate the CCEL, comprising: generating a pulse width modulation control signal that has different operation cycles T on and T off ; and generating a high frequency AC signal with different frequencies f 1 and f 2 at the different operation cycles T on and T off of the pulse width modulation control signal to actuate the piezoelectrie transformer to alter the output voltage and the output current of the piezoelectric transformer thereby to module the luminosity of the CCFL; the piezoelectric transformer generates a first voltage gain at the frequency f 1 of the operation cycle T on and generates a secondvoltage gain at the frequency f 2 of the operation cycle T off , the first voltage gain being greater than the second voltage gain.