Discharge lamp lighting circuit with protection circuit

摘要

A discharge lamp lighting circuit 1 has a DC power supply section 4 for receiving power supply from a DC power supply 2, a DC-AC conversion section 5 for converting an output voltage of the DC power supply section 4 into an AC voltage and then applying the AC voltage to a discharge lamp 8, and a starter circuit 6 for applying a high-voltage pulse to the discharge lamp 8 for starting the lamp. A control circuit 7 detects an anomaly occurring in the discharge lamp or the lighting circuit and stops supplying power to the discharge lamp 8 and also lights another light source as an alternative light source to the discharge lamp 8 or notifies a driver of occurrence of the anomaly. An internal state monitoring circuit 26 is provided for monitoring the operation state of the control circuit itself and when an anomaly about the control circuit 7 is detected, the alternative light source is lighted or the driver is notified of occurrence of the anomaly.