| 摘要 |
PURPOSE:To reduce the starting time for a discharge lamp by adding a voltage produced between non-power side electrode terminals of a pair of filament of the discharge lamp to a control input terminal of a voltage determination switch through a serial circuit of a parallel circuit of a Zener diode and a capacitor and a resistor from the discharge lamp side of a delay switch. CONSTITUTION:When a delay switch SW is closed, a voltage determination switch SCR becomes continuous to discharge a capacitor C1, and a large current is supplied to the control input terminal of the voltage determination switch SCR through a resistor R1 and the capacitor C1. A threshold voltage for determining a voltage between non-power side electrode terminals T1, T2 of a pair of filaments f1, f2 of a discharge lamp DL thus becomes low. When the delay switch SW is closed to be preheated previously just after charging the power, the continuity phase of the voltage determination switch SCR advances to increase a preheating current to be supplied to the filaments f1, f2. The starting time of the discharge lamp can thus be reduced. |
