| 摘要 |
PURPOSE:To prevent a drive transistor from damaging by absorbing a surge voltage induced in the primary winding of a current transformer through the secondary winding and a feedback winding of the transformer by a surge absorber. CONSTITUTION:Surge voltages are generated in the secondary windings L11, L21 through the secondary windings L12, L22 and feedback windings L13, L23 of current transformers T1, T2 when a discharge lamp is started and fired or when the phase of the current flowed to the lamp is advanced. The surge voltage is applied through a closed circuit of diodes D3, D4 to a surge absorber 9. A current is flowed through the closed circuit of the diodes D3, D4, the surge absorber 9, a capacitor C8 and a resistor R5 by the surge voltage, and clamped. Therefore, the surge voltage of the rated maximum absolute voltage or larger is not applied to drive transistors Q3, Q4. |
