DISCHARGE LAMP LIGHTING DEVICE

摘要

PROBLEM TO BE SOLVED: To improve the safety and suppress the effect of malfunction due to noise and the like by surely detecting an abnormal state of a discharge lamp and taking protective actions. SOLUTION: The discharge lamp 1 is lit by a high frequency output of an inverter circuit 3 and the operation of the inverter circuit 3 is controlled by a control circuit 8. This discharge lamp lighting device is provided with a filament disconnection determining circuit 4 detecting the disconnection of a filament of the discharge lamp 1 and issuing an abnormality signal, a protection means responding to the abnormality signal and raising the oscillation frequency of the inverter circuit 3 and a protection means of stopping the inverter circuit 3 incorporated in the control circuit 8, and two transmission circuits 7 and 13 transmitting the abnormality signal to the two protection means at different response times. The response time of the transmission circuit 7 transmitting the abnormality signal to the protection means for stopping the inverter circuit 3 is made longer than the response time of the transmission circuit 13 transmitting the abnormality signal to the protection means for raising the oscillation frequency of the inverter circuit 3. COPYRIGHT: (C)2004,JPO