| 摘要 |
PURPOSE:To improve the power factor while securing the constancy of a smooth voltage, by connecting the first and the second diodes between a DC power source and a capacitor for smoothing, and between the DC power source and the second switching element side of a resonance capacitor respectively. CONSTITUTION:When a resonance inductor voltage VCO generated by the resonance of the resonance inductor L0 of an inverter circuit 5 and a resonance capacitor C0 is made equal to the power source voltage Vin, the second diode D4 is turned ON. As a result, a power factor improving current flows from the second switching element S3 to a capacitor C1 for smoothing through the resonance inductor L0, and a current with a high peak to the capacitor C1 can be suppressed. Consequently, a low distortion circuit which can maintain the smooth electrode constant as well as can improve the power factor in a simple structure is formed. And the voltage applied to the discharge lamp as a load 8 is made flat. |
