| 摘要 |
PURPOSE:To keep load impedance constant even just after OFF of a starting switch and satisfactorily supply a power to a lamp by connecting a fifth capacitor in parallel to both ends of the resonance circuit part and starting switch in a starting circuit. CONSTITUTION:To start a lamp 14, a starting switch 12 is ON to supply a power from an inverter 3 to a main circuit and a starting circuit 18. A high voltage is applied to a gas probe 14b, and a plasma ring is formed in a main tube 14a. When the switch 12 is then opened, a parallel resonance circuit 16 is cut from the main circuit, while the series circuit of third and fifth capacitors 8, 17 is laid in the state connected in parallel to an exciting coil 7 to cancel the inductance excess of the main circuit, and the load impedance can be kept constant. Thus, a sufficient power is supplied from the inverter 3 to the lamp 14, and inconveniences such as the failure of the lamp 14 can be prevented. |
