| 摘要 |
PURPOSE:To realize stable lighting control of a discharge lamp in high frequency lighting of the discharge lamp. CONSTITUTION:A resonance circuit (an inductor 11 and a capacitor 14) is arranged in the rear stage of a DC-AC converting circuit 7, and a control circuit 22 varies an oscillation frequency of a frequency variable oscillating part 28 according to signals from a voltage detecting part 23, an electric current detecting part 24 and a timer circuit 25, and thereby varies a frequency of output voltage of the DC-AC converting circuit 7, and controls supply voltage to a discharge lamp 20. Resonance maintaining voltage in the resonance circuit is used as voltage necessary to transfer the discharge lamp 20 to arc discharge from glow discharge, and stable lighting of the discharge lamp 20 is performed under constant power control by the control circuit 22. |
