| 摘要 |
PURPOSE:To enhance serviceability by enabling oscillation to be precisely stopped or an output to be limited when an electric discharge lamp has come to its end, and lighting other electric discharge lamps under no load. CONSTITUTION:A plurality of fluorescent lamps 70-72 are lighted in parallel by the LC series resonance of inductors 90-92 and capacitors 70 72. The lamp voltages of the fluorescent lamps 70-72 are divided by resistors 230-232 and 240-242 and detected by a control portion 29. In order to enable a no-load voltage and a fluorescent-lamp life-end voltage to be distinguished one from the other, a no-load detecting circuit B is provided, and a voltage detected by the control portion 29 is regarded as a ground voltage when the lamps are under no load. Therefore, it is made possible to discriminate between the end of an electric discharge lamp and a no-loaded condition. |
