Lighting circuit for discharge lamp

摘要

A lighting circuit for a discharge lamp is designed in such a way that a detection time for the flicker state of a discharge lamp is not affected by the light-OFF time at the time the discharge lamp flickers without causing a significant increase in cost. This lighting circuit 1 for a discharge lamp comprises detection means 5 for detecting a flicker state of a discharge lamp 3; and abnormality determining means 6 for determining an abnormality in the discharge lamp 3 in accordance with a detection signal from the detection means 5 and implementing display to that effect, or stopping power supply to the discharge lamp 3, whereby when the detection signal from the detection means 5 indicates repetition of a state where a light-OFF time of the discharge lamp 3 is equal to or greater than a first set time and a light-ON time of the discharge lamp 3 is equal to or less than a second set time is repeated a predetermined period or longer, or a predetermined number of times or more, the abnormality determining means 6 determines the state as abnormal lighting of the discharge lamp 3.