| 摘要 |
PROBLEM TO BE SOLVED: To provide a projection type video display device capable of controlling ambient temperature near a projection lens unit to be nearly constant, and suppressing and reducing the amount of thermal expansion of the projection lens unit, the volume change of a projection lens and the change of the refractive index of the projection lens, thereby suppressing the out-of-focus of a video on a screen. SOLUTION: The projection type video display device is equipped with: a temperature sensor set to operation temperature the same as the ambient temperature of the projection lens unit when the projection lens is focused; a first blast path internally provided with a light source; a first fan for cooling the light source; a second blast path internally provided with the projection lens unit; a second fan for cooling the projection lens unit when the temperature sensor detects the temperature equal to or above the set temperature; and a third blast path having the exhaust ports of the first blast path and the second blast path. The third blast path is provided with a current-of-air direction switching device which sends warm air warmed by the light source to the second blast path side by stopping the second fan when the temperature sensor detects the temperature equal to or under the set temperature, and keeps the temperature near the projection lens unit the same as the set temperature. COPYRIGHT: (C)2008,JPO&INPIT
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