LIGHTING DRIVING DEVICE OF COLD-CATHODE TUBE

摘要

PROBLEM TO BE SOLVED: To provide a lighting driving device of a cold-cathode tube capable of equally controlling a plurality of cold-cathode tubes by controlling tube current without increasing loss electric power. SOLUTION: The lighting driving device of the cold-cathode tube is equipped with a one input two output type piezoelectric transformer outputting opposite phase AC voltage from a first output electrode and a second output electrode; a current detecting element inserted between two cold-cathode tubes connected in series between the first output electrode and the second output electrode; a current detecting circuit comprising a first differential amplifier in which voltage at both ends of the current detecting element is inputted; a second differential amplifier comparing output of the current detecting circuit with reference voltage; an oscillation circuit controlling the driving frequency of the piezoelectric transformer so that the current floating through the cold-cathode tube becomes constant based on the output of the second differential amplifier; and a driving circuit inputting AC voltage in the piezoelectric transformer based on the driving frequency oscillated from the oscillation circuit. COPYRIGHT: (C)2004,JPO&NCIPI