| 摘要 |
PURPOSE:To reduce a mechanical error by controlling a lens so that the lens is always moved in the same direction before stop in a copying machine where variable power can be executed by a zoom lens. CONSTITUTION:In case that a magnification m' set to the zoom lens is changed to a magnification (m), the magnification (m) is read into a microcomputer 72 by depression of a ten-key 73. The microcomputer 72 compares magnifications m' and (m) with each other and switches a motor rotation direction switching circuit 71 to the forward rotation side of a servo motor 48 in case of (m)>m' and switches this switching circuit 71 to the reverse rotation side of the servo motor 48 in case of (m)<m'. Next, the microcomputer 72 takes out a clock pulse number n', which corresponds to a distance d' from a reference position to a lens position corresponding to the initial magnification m', and a clock pulse number (n) corresponding to the designated magnification (m) from a storage part and calculates N=1n-n'1. The calculated clock pulse number N is set to a counter part, and a control signal is given to a motor applied voltage switching circuit 70. |
