Patent ID: 7164239

Claim:
A discharge lamp ballast circuit comprising: an inverter for converting a DC voltage to an AC voltage, and for boosting the AC voltage; an igniter for generating from the AC voltage boosted by said inverter a DC voltage higher than a breakdown voltage of a discharge lamp, or a superimposed voltage in which a pulsating component is superimposed on the DC voltage, and for supplying the discharge lamp with one of the DC voltage and the superimposed voltage to start discharge; and a resonant circuit that is connected to an output side of the inverter, and resonates in response to a load of the discharge lamp, wherein said resonant circuit comprises: a first reactor connected in parallel with the output side of the inverter; a second reactor having its first end connected to a first end of said first reactor; a first capacitor having its first end connected to a second end of said second reactor, and its second end connected to a first end of the discharge lamp; and a second capacitor having its first end connected to the second end of said second reactor, and its second end connected to a second end of said first reactor and to a second end of said discharge lamp.