US Patent 7235931 Discharge lamp lighting apparatus for lighting multiple discharge lamps

In a discharge lamp lighting apparatus to light two discharge lamps, one terminal of the secondary side of a step-up transformer is connected to one terminal of each of the two discharge lamps, the other terminal of each of the two discharge lamps is connected, via each of two variable inductance elements, to one lamp current detecting unit, a signal of each lamp current detecting unit is connected to a lamp current control circuit, and an output signal from each lamp current control circuit is connected to each variable inductance element so as to vary the inductance of each variable inductance element, whereby the lamp current flowing through each discharge lamp is controlled.