| 摘要 |
PROBLEM TO BE SOLVED: To restrain an electric power loss for detecting a load state with the simple circuit constitution, to secure large a changing width of a load state detecting signal when performing continuous light dimming control, and to enable highly accurate and wide continuous light dimming in a discharge lamp lighting device. SOLUTION: A discharge lamp 21 is lighted by obtaining high frequency electric power by performing resonance operation between the discharge lamp and a load circuit 20 by controlling ON/OFF of a switching element Q1 of an inverter circuit 10. Here, since the load state detecting signal for performing feedback control is generated from end-to-end voltage of a capacitor C2 inserted in series into the discharge lamp 21, the electric power loss is restrained as compared to the constitution of a resonance current monitor by a conventional resistance, and a large detecting signal difference can be obtained at continuous light dimming time. |
