| 摘要 |
PURPOSE:To obtain many division patterns of a zoom encoder by preventing a cam cylinder, which is rotated in accordance with movement of a zoom ring, from being moved in the direction of the optical axis to a fixed barrel and sticking a brush to the cam cylinder and providing the zoom encoder on the peripheral surface of the fixed barrel. CONSTITUTION:A cam cylinder 4 is rotatably fitted to the outside of a second fixed barrel 11, and a pin 15 stood on the second fixed barrel 11 is fitted into a peripheral groove 4d to prevent movement of the cam cylinder in the direction of the optical axis. Brushes 7 are stuck to a holding member 22, and the holding member 22 is fixed to the cam cylinder 4 by a screw 23, and a zoom encoder 6 is adhered to the outside peripheral surface of the fixed barrel 11, and four division patterns are provided on the zoom encoder, and four brushes 7 are slid on them. A zoom ring 2 is stuck to a one-group moving frame 9 by a screw 24, and a knurling tool is provided on the outside peripheral surface of the zoom ring to prevent slip at the time of zooming operation. Thus, the length of the division pattern part on the zoom encoder is extended and the number of divisions of division patterns is increased.
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