DISCHARGE LAMP LIGHTING DEVICE

PROBLEM TO BE SOLVED: To reduce cost by simplifying a lamp life period detecting means and a lamp connection detecting means and simplifying circuit configuration. SOLUTION: This device is equipped with a rectifying circuit 2 for obtaining a direct-current voltage by full-wave rectifying commercial alternating-current power 1, a boosting circuit 3 for an output voltage from the circuit 2, an inverter circuit 4 for converting the boosted voltage into a high-frequency voltage to be outputted, a circuit 5 for driving/controlling the circuit 4, discharge lamps 6a, 6b one end of each of which is connected to the positive output side of the circuit 4 via ballast coils 7a, 7b, respectively, the other end of each of which is connected to the negative output side of the circuit 4 via a capacitor 8 for direct current cutting, so as to be lit by alternately supplying them with the high-frequency voltage, a first comparator 20 for life period detection for comparing the voltage of a connection point connected to the other ends of the two lamps with a first threshold voltage and outputting a drive stopping signal to the circuit 5, when the connection point voltage is lower than the first threshold value, and a second comparator 21 for comparing the connection point voltage with a second threshold which is lower than the first threshold and outputting a drive stopping signal to the circuit 5, when the connection point voltage is lower than the second threshold.