| 摘要 |
PROBLEM TO BE SOLVED: To provide a very reliable reduction gear unit capable of eliminating adverse influence of grease or the like with which a gear is filled by improving the resolution for detecting pulses for counting the revolving speed of a motor with a simple structure, a reduction gear unit assembling method and a zoom device for camera using the reduction gear unit. SOLUTION: Gears 30, 31, 32, 33 and 35 are assembled in a gear box 4. An impeller 21 and a pinion 23 are attached on the output shaft of a motor 2, and the pinion 23 on the output shaft is meshed with the input gear of the gear box, so that the motor 2 is fixed in the gear box. The impeller 21 is housed in space partitioned off from the pinion housing part of the gear box 4. A sensor 27 for detecting the rotation of the impeller 21 is attached and the gear box is hermetically sealed with a cover. Thus, a gear train is easily formed and the sensor can be prevented from being adversely influenced by the scattering of the grease. COPYRIGHT: (C)2004,JPO&NCIPI
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