DRIVING DEVICE AND DRIVING METHOD OF COLD CATHODE FLUORESCENT TUBE USING PIEZOELECTRIC TRANSFORMER

摘要

PROBLEM TO BE SOLVED: To prevent the problem that the output voltage of the piezoelectric transformer becomes high when it is connected to plural cold cathode tubes. SOLUTION: In a piezoelectric transformer in which voltage inputted from the primary side electrode is outputted from the two secondary side electrodes by piezoelectric effect, the driving frequency of the piezoelectric transformer is fixed and the two output powers of the piezoelectric transformer are inputted into the two terminals of the cold cathode fluorescent tubes, and the phase difference between the input and output voltage of the piezoelectric transformer is detected, and control is made so that the phase difference may be constant.