Patent ID: 8523365

Claim:
A light source device comprising: an arc tube having a bulb portion emitting a luminous flux; a sealing portion extending from the bulb portion to a side to which the luminous flux is emitted; a reflector fixing the arc tube and reflecting the luminous flux; and a holding portion holding the reflector, the holding portion including: an inlet port positioned lateral to the arc tube and introducing cooling air into the holding portion in a direction which is orthogonal to an optical axis of the luminous flux; a partition provided between the inlet port and the arc tube; a pair of passages to which the top and bottom of the arc tube diverges in the partition, and can circulate the cooling air to the arc tube; a first opening provided in the partition and through which a part of the cooling air from the inlet port passes; and a shutter provided on that side of the partition where the inlet port is located, rotating around a rotation axis which is parallel to the optical axis, and blocking a lower passage of the pair of passages, wherein the shutter has a second opening on a side of the shutter where the rotation axis is located, and the second opening is provided so as to overlap the first opening as seen from the inlet port.