DRIVE CIRCUIT FOR PIEZOELECTRIC TRANSFORMER, LIGHT- EMITTING DEVICE FOR COLD-CATHODE TUBE, LIQUID CRYSTAL PANEL AND LIQUID CRYSTAL PANEL EMBEDDED APPARATUS

摘要

PROBLEM TO BE SOLVED: To surely light all cold-cathode tubes connected to a piezoelectric transformer, to reduce a difference in luminance of each cold-cathode tube in normal lighting, and to improve the reliability and performance of a device. SOLUTION: A drive circuit for the piezoelectric transformer is provided with: a plurality of cold-cathode tubes 7, 8 connected to a secondary side of the piezoelectric transformer 1; and a cold-cathode tube output detecting circuit 20 that is connected to the plurality of cold-cathode tubes in series and detects the output state of each cold-cathode tube. The piezoelectric transformer is drive-controlled based on a detected signal from the cold-cathode tube output detecting circuit, and the piezoelectric transformer can thereby perform the same operation as an operation performed to one cold-cathode tube. COPYRIGHT: (C)2003,JPO