DISCHARGE LAMP LIGHTING DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device whose switching loss is reduced as well as down-sizing and cost down of the device are attempted. SOLUTION: An inverter circuit 7 is composed of the first and second diodes D1 , D2 respectively connected in reversely parallel to the first to fourth switching elements S1 to S4 in a bridge shape and to the second and the fourth switching elements S2 , S4 . A control part 2 makes the second and fourth switching element S2 , S4 to carry out their on/off operation alternately at a low frequency and also makes the first switching element S1 to carry out its on/off operation at a high frequency when the fourth switching element S4 is turned on and makes the fourth switching element S4 to carry out its on/off operation at a high frequency when the second switching element S2 is turned on. The control part 2 turns on the first or third switching elements S1 , S3 when an electric current flowing to the first or second diode D1 or D2 is found to become zero from the current flowing in a transformer T1 .