Lighting apparatus for discharge lamps with preheating filaments

摘要

The discharge lamp lighting apparatus of the present invention includes an inverter 1 to convert input DC voltage into high frequency voltage and supply the converted high frequency voltage to a discharge lamp 2 having filaments, a preheating circuit C1 to preheat the filaments of the discharge lamp 2, a filament voltage detecting circuit 3 to detect voltage applied between both ends of the filaments of the discharge lamp 2, and an output controlling circuit 7 to control the inverter to stop or lower the output of high frequency voltage when the detected result of the filament voltage detecting circuit 3 exceeds a specified value.