US Patent 7830098 Projector and light source device thereof

A light source device includes: a first electrode and a second electrode, a light emitting tube, a main reflection mirror disposed on the first electrode side, a sub reflection mirror disposed on the second electrode side and a current driving device which supplies alternating current and performs power control such that supply energy during an anode period of the first electrode becomes smaller than supply energy during a cathode period of the first electrode at least a predetermined period immediately before a stable operation starts in the period from the start of power supply to the first and second electrodes to the start of the stable operation.