DISCHARGE LAMP LIGHTING DEVICE

PROBLEM TO BE SOLVED: To offer an inexpensive circuit permitting precise detection of the presence the filament of a discharge lamp independently of any condition change of the loaded discharge lamp. SOLUTION: This discharge lamp lighting device comprises a non-load detection circuit for discriminating the presence of the filament of the loaded discharge lamp in accordance with the presence of the DC voltage supplied from a DC power supply via the filament. After an inverter circuit starts oscillation, high frequency voltage generated by the inverter circuit or the DC voltage supplied via the filament, whichever higher, is applied to the non-load detection circuit, and during the half-wave discharge to the loaded discharge lamp, at least the high frequency voltage generated by the inverter circuit is applied to the non-load detection circuit. COPYRIGHT: (C)2003,JPO