| 摘要 |
PURPOSE:To eliminate the restriction of the selection of the constant of a main lighting circuit by setting the synthetic impedance of an LC serial resonance circuit and the impedance of an ignitor sufficiently high. CONSTITUTION:An inverter IN switches at least one of switching elements Q1, Q2 to convert the DC power voltage into the high-frequency voltage. The elements Q1, Q2 form an oscillating resonance circuit together with capacitors C1, C2 when they are closed. The synthetic impedance of an LC serial resonance circuit is set sufficiently high against the oscillation frequency of the oscillation circuit of an ignitor IG. The impedance of the circuit including the impedance element of the ignitor IG connected in parallel with a discharge lamp DL is set sufficiently large against the lighting frequency of the discharge lamp DL. When the discharge lamp DL is ordinarily lighted, the voltage not affecting the elements Q1, Q2 and the resonance circuit is used. The ignitor IG gives no restriction on the selection of the constant of a main lighting circuit, and no effect in the electric capacity is given to the elements Q1, Q2. |
