DISCHARGE LAMP LIGHTING DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device capable of surely detecting the abnormal lighting state of a discharge lamp. SOLUTION: A dimming control circuit 3b controls the oscillation state of an oscillation control circuit 3a in response to the dimming signal Vs to change the output of a high-frequency power supply 1. A lamp operation point switching controller 5 periodically switches multiple lamp operation points at the time of dimming to continuously change the light output of a discharge lamp 2. In an abnormality detection section 4, an abnormality detecting circuit 4a detects the lighting state of the discharge lamp 2, and an abnormality judging circuit 4c compares the detected output of the abnormality detecting circuit 4a with the reference voltage of a reference setting circuit 4b to judge whether the lighting state is abnormal or not and stops the output of the high-frequency power supply 1 in the abnormal lighting state. The abnormality detection section 4 is provided with a malfunction preventing means preventing the malfunction of the abnormality detection section 4 at the time of the switching action of the lamp operation points.