| 摘要 |
PROBLEM TO BE SOLVED: To realize very long life of a cooling fan assembly by restraining acceleration of abrasion to a cooling fan driving bearing or the like. SOLUTION: A tank 1 is installed on the top of a laser chamber 6, a cooling fan 4 is provided in the tank, rotation driving force from a motor 7 is transmitted though a magnetic coupling 8. Magnetic switches SR1, SR2, SR3 and transformer Tr1 are provided in the tank 1 in a tiered-box shape. A fan control device 20 detects a trigger signal from the outside, checks whether or not there is the trigger signal within a predetermined period. When the trigger signal is received within the predetermined period, the cooling fan is rotated with a motor 7 turned on. When the trigger signal is not received within the predetermined period, the operation of the cooling fan 4 is stopped. The motor 7 may be turned on/off or its rotational speed may be set corresponding to the average value of intervals of the trigger signals or the temperature of isolated refrigerant 5 or the like. COPYRIGHT: (C)2004,JPO
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