| 摘要 |
PURPOSE:To enable the formation of an original image at an exact magnification by returning an optical member once to a reference position after plural times of operations at changed magnifications are performed then moving the optical member. CONSTITUTION:When a motor 29 is run forward and a lens is kept moved in an arrow A direction, a microswitch 45 emits a signal upon lapse of certain time. The signal indicates the arrival of the lens at a reference position but in some cases the lens stops in the position deviated from said reference position. A torque limiter 25 is provided in the route where the driving power is transmitted to a lens base 16, in order to correct said deviation. The torque limiter is designed to continue the operation of the motor 29 up to the point of the time slightly after the point of the time when the switch 45 forms the signal and to de-energize the motor 29 after a bearing 18 is held pressed positively to a stopper 44 by such continued operation, that is, after the lens is correctly stopped and held in the reference position. |
