Patent ID: 8596796

Claim:
A projection display device comprising: a light source unit that includes a discharge lamp as a light source; an image formation unit; a projection optical system; and a light source cooling unit that cools the light source unit, thereby projecting an image displayed on the image formation unit by using light emitted from the light source unit, wherein the light source unit is disposed so that a lamp axis that connects two discharge electrodes of the discharge lamp is orthogonal to a projecting direction of the projection optical system, the light source unit comprises: a concave mirror whose central axis matches the lamp axis and that reflects the light emitted from the discharge lamp; and a transparent part that covers an opening of the concave mirror, and the light source cooling unit comprises: a blowing fan that supplies cooling air; a plurality of air blowing ports disposed in a circumferential portion of the concave mirror or a connecting part that connects the concave mirror and the transparent part, at positions corresponding to directions in which they are orthogonal to each other with the lamp axis as a center when viewed in the lamp axis direction; an air duct that forms a plurality of branch flow paths connecting the air blowing ports and the blowing fan; a branch switching valve that is disposed in the air duct and switches between the branch flow paths so as to allow the cooling air supplied by the blowing fan to flow therethrough; and a plurality of control valves, each of the air blowing ports being provided with one of the control valves, each of the control valves being rotated around a rotation axis that extends in a direction orthogonal or parallel to the lamp axis by the action of gravity depending on a posture of the light source cooling unit, thereby controlling a wind direction so that the cooling air is blown from above the discharge lamp, wherein each of the control valves is formed of an air control baffle that is rotatable around the rotation axis, the branch switching valve operates so as to send an airflow from an entrance of the air duct toward the air blowing port postured in a vertical direction among the air blowing ports disposed orthogonal to each other, while blocking an airflow toward the air blowing port postured in a horizontal direction, and each of the air control baffles is configured such that when the air blowing port postured in a vertical direction is positioned above the discharge lamp, the air control baffle is inclined, so that airflow through the air blowing port flows into the concave mirror in an oblique direction, thereby being blown toward the top of the light source lamp, and when the air blowing port postured in a vertical direction is positioned below the discharge lamp, the air control baffle hangs in a vertically downward direction, so that airflow through the air blowing port is guided in a vertically upward direction and then flows along the shape of the concave mirror, thereby being blown toward the top of the light source lamp.