| 摘要 |
PROBLEM TO BE SOLVED: To provide a discharge lamp lighting apparatus capable of giving a sufficient preheating current to the filament, when the lamp is off, and capable of completely turning off the lamp without a tube end of the discharge lamp glowing during the stand-by time. SOLUTION: This discharge lamp lighting apparatus comprises a DC power supply, an inverter circuit for inverting the output of the DC power supply to high-frequency power, a resonance circuit connected to the output of the inverter circuit, a discharge lamp driven by the resonance of the resonance circuit, an inverter control circuit for varying the output of the inverter circuit, and a modulated light control circuit for light modulation control and on/off control of the discharge lamp by inputting a light modulation signal from the outside. When the discharge lamp is off, at least two levels of pre-heating currents are fed to the filament of the discharge lamp switched with a prescribed cycle. A first period Tb, when the level of the pre-heating current If, is set high and a second period Ta, when the level of the pre-heating current is set low, are switched alternately, and the first period Tb is set sufficiently shorter than a second period Ta. |
