| 摘要 |
PROBLEM TO BE SOLVED: To correct deviations from the optimum value of on-duty at frequency ripple of voltage applied to a piezoelectric transformer caused by input voltage change or dimming operation, etc. SOLUTION: Correction of on-duty is performed by providing a frequency controller 10a, which controls the frequency of the voltage applied to a piezoelectric transformer, with an on-duty resistor 12, which performs the correction to the ripple of input voltage by adding a voltage value which is proportional to the input voltage thereby correcting the reference value, and a dimming on duty switching circuit 13, which corrects the reference value by switching a voltage dividing resistor for correcting the reference value through switching of the voltage dividing resistor for creating a reference value by the existence of dimming operation, and controlling the frequency with the corrected reference value. |
