| 摘要 |
PROBLEM TO BE SOLVED: To protect the circuit by detecting steadily the phenomena of the end of the life of the discharge lamp by a simple structure. SOLUTION: This is a discharge lamp lighting device in which a parallel capacitor C1 is provided in one of switching element Q1 in the half-bridge inverter circuit 1 and by charging and discharging this parallel capacitor C1 by the electric current flowing in a load circuit 2 including the LC resonance circuit and the discharge lamp La, steep change of the voltage of the switching element is alleviated and the switching loss or the noise is reduced. When the lamp impedance has become large at the end of the life or the like, the phenomena in which the charging current of the parallel capacitor C1 flows through a switching element Q2 is detected by a differentiation circuit 4, and the output of the inverter circuit 1 is reduced or stopped. COPYRIGHT: (C)2003,JPO |
