DISCHARGE LAMP LIGHTING DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device capable of stably lighting a discharge lamp of a relatively large lamp voltage while securing electrical safety. SOLUTION: A pulsating voltage obtained from rectification of ac power is applied between terminals (p), (q) and is stepped up by a chopper circuit 10. The output of the chopper circuit 10 is converted to a high frequency AC output by an inverter circuit 20. The output of the inverter circuit 20 is stepped up by an AC-AC converter circuit 30 and supplied to a discharge lamp La. The inverter circuit 20 adjusts the AC electric power of the output by changing a switching frequency with which switching elements Q2 , Q3 are alternately turned on and off by an inverter control circuit 21 at high frequencies. Also, when the rated voltage of the discharge lamp La is not less than 140 V, the inverter control circuit 21 regulates a dimming ratio lower limit value so that the lamp voltage is less than 300 V during dimming.