| 摘要 |
<p>A code plate (6) of an incremental encoder is fixedly mounted to a first rotor (4) which is rotatably supported on a housing (1); a small-diameter portion (4a) and a large-diameter portion (4b) are formed on the outer peripheral surface of the first rotor; and furthermore a pair of engaging projections (17a/17b) are formed on both sides of a clearance groove (16) formed in the large-diameter portion. A rotating ring is mounted on the inside bottom surface of the housing; on the rotating ring is formed a driven gear through a range of about 90 degrees, and a shield plate is erected in a position corresponding to the driven gear. Five photo-interrupters (13a-13e) are arranged astride the shield plate on the path of rotation of the rotating ring, so that the position of the rotating ring can be detected by the ON/OFF operation of the photo-interrupters. On the housing an intermediate gear (14) is rotatably supported, and is in constant mesh with the driven gear. On the intermediate gear are provided a first tooth portion and a second tooth portion, which are arranged 45 degrees apart from each other. The first tooth portion faces the small-diameter portion of the first rotor, while the second tooth portion faces the large-diameter portion, whereby the intermediate gear is turned through about 90 degrees by the engaging projections during one rotation of the first rotor, thus turning the rotating ring by two teeth of the driven gear. <IMAGE></p> |
