| 摘要 |
PROBLEM TO BE SOLVED: To reduce noise (whistling) caused by an air intake fan and an exhaust fan which are provided in a main body of a liquid crystal projector. SOLUTION: An exhaust fan 3 is provided on the side face on the light source lamp side of an enclosure 1 of the main body of the liquid crystal projector, and an air intake fan 2 which has the same shape and the same rotational frequency as the exhaust fan is provided in a position facing the exhaust fan, namely, in a position of the same height from the bottom and the same distance in the horizontal direction as the exhaust fan on the other side of the enclosure. The propagation speed of sounds in air is divided by the frequency of whistle and the quotient is divided by 2, and the result is used as an interval x between two fans so that whistles of two fans may be canceled by each other. The noise level is about zero at a point A, and it is reduced at other positions.
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