| 摘要 |
PROBLEM TO BE SOLVED: To provide a lighting device for discharge lamp in which circuits are adequately protected at the last life stage in accordance with a light modulation level. SOLUTION: An AC power source Vs is converted to a designated direct current voltage in an AC/DC converter circuit 1', and a discharge lamp La is lighted at a high frequency by an inverter part 30, with the direct current voltage as a power source. When it is detected that the discharge lamp La is emissionless in an emissionless detecting circuit 7 connected to the inverter part 30, an oscillation stopping signal is sent to an oscillation control circuit 5 to control an inverter circuit 3 and oscillating operation is stopped. At the same time, an actuating signal for a stop timer is sent to a stop timer circuit 6 to actuate the stop timer circuit 6, by this stop timer circuit 6 the stopping time of the oscillating operation is controlled to a designated time corresponding to a light modulation level shown by a modulated light signal from a dimmer 7, and when a designated time has elapsed, the inverter part 30 is re-started by sending a re-starting signal from the stop timer circuit 6 to the oscillation control circuit 5. |
