Driving circuit and driving method for piezoelectric transformer, backlight apparatus, liquid crystal display apparatus, liquid crystal monitor, and liquid crystal TV

摘要

A driving circuit for a piezoelectric transformer is provided, which is capable of driving a piezoelectric transformer at a high efficiency and with low distortion, and being miniaturized. At the commencement of lighting a cold-cathode fluorescent tube, a digital controller fixes frequencies of first and second control signals VC 1 and VC 2 at a predetermined frequency and controls the phase difference therebetween so that an output power of the piezoelectric transformer becomes from substantially zero to a predetermined output power. After lighting of the cold-cathode fluorescent tube, the digital controller controls the phase difference between the first and second control signals VC 1 and VC 2 so that current detecting data CD substantially is matched with reference data RD.