Patent ID: 8408714

Claim:
A light source device comprising: an arc tube having a light emission portion and a first sealing portion extending from one end of the light emission portion; a first reflection mirror attached to the first sealing portion and having a substantially concave surface for reflecting light emitted from the light emission portion; and a container which accommodates the arc tube and the first reflection mirror, wherein: the arc tube has a second sealing portion extending from the end of the light emission portion opposite to the end from which the first sealing portion extends, the container has a duct unit disposed above the arc tube and extending along the center axis of light reflected by the reflection surface such that cooling air can flow in the direction opposite to the traveling direction of light reflected by the reflection surface, the duct unit includes: a first opening open to the arc tube and disposed at a position shifted toward the traveling direction side from an opening end of the first reflection mirror, a wall portion which forms the edge of the first opening on the side opposite to the traveling direction side as a final end of the duct unit, an inclined portion disposed in the vicinity of the edge of the first opening on the traveling direction side to bend the flowing direction of the cooling air toward the surface opposite to the surface having the first opening, the inclined portion extending away from the first opening in a sloping direction that is obliquely in the traveling direction and toward the center axis of the light reflected by the reflection surface, a branch portion having a second opening which branches a part of the cooling air flowing within the duct unit to guide the part of the cooling air to the second sealing portion, a first duct portion and a second duct portion disposed opposed to each other with the center of the arc tube interposed between the first and second duct portions, each of the first and second duct portions having the first opening, the wall portion, and the inclined portion, and a guiding member which directs the cooling air toward the first duct portion or the second duct portion positioned above the arc tube by moving by its own weight, and the second opening straddles the first duct portion and the second duct portion.