POWER SUPPLY UNIT, LIGHTING DEVICE FOR ELECTRIC DISCHARGE DEVICE AND LIGHTING SYSTEM

摘要

PURPOSE: To prevent a distortion of input current from an AC power supply by a simple circuit configuration. CONSTITUTION: In a period in which MOSFET21 of a first switching means is turned off and the MOSFET22 of a second switching means is turned on, a resonance voltage is generated at a second capacitor C2 and inductor 24, and the distortion can be reduced by applying a power factor improvement current because of the effect of the resonance voltage even during a period when the peak value of the voltage rectified by a rectifying circuit 12 is low. In this case, the MOSFET21 applied of the resonance voltage has a higher withstand voltage than that of the MOSFET22 is used thereby providing both a low cost and a high reliability at the same time.