| 摘要 |
PURPOSE:To provide a small-sized and inexpensive discharge lamp lighting device capable of avoiding acoustic resonance phenomenon and stably lighting a discharge lamp. CONSTITUTION:A control circuit 4 continues the ON state of a switching element S1 (or S2) which was ON till then at a point of time when the voltage of a capacitor C0 is substantially zero, and also turns ON the switching element S2 or S1 which was OFF till then. By the simultaneous ON operation, an inverter circuit 2 releases the charge of the capacitor C0 and accumulates a magnetic energy in an inductor Ls by a DC power source 1 according to the length of the ON period. This accumulated energy forms the energy of resonance for raising the wave height value and effective value of resonance voltage when the switching element S1 (or S2) is OFF. Since the simultaneous ON period is variably set according the power source voltage, the operating frequency of the inverter circuit 2 is also changed, the impedance value of an inductor L1 is consequently changed, and the output power is made substantially constant. |
