Patent ID: 7830098

Claim:
A light source device, comprising: a first electrode and a second electrode which cause light emission by electrical discharge between each other; a light emitting tube having a main body containing a discharge space which separates the first and second electrodes disposed within the main body, and sealing portions provided at both ends of the main body; a main reflection mirror disposed on the first electrode side to reflect source light generated by the discharge between the first and second electrodes and emit the reflected light toward an illuminated area; a sub reflection mirror disposed on the second electrode side at a position opposed to the main reflection mirror to reflect the source light toward the main reflection mirror side; and a current driving device which supplies alternating current for causing electrical discharge between the first and second electrodes to the first and second electrodes, 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.