BACK FOCUS ADJUSTING DEVICE FOR LENS OF OPTICAL SYSTEM

摘要

PURPOSE:To perform highly accurate adjustment using simple structure by moving the support of a variable magnification lens by a cylindrical cam. CONSTITUTION:A cylindrical cam 25 is mounted to the central flange 4B of the support 4A of variable magnification lens of a copying machine, and a cylindrical cam 29 having a gear 29C is placed on it. When magnification is designated with a magnification setting device 34 to change magnification of copying, a motor 31 is driven by a motor circuit 33 which is controlled by a microcomputer, and the cam cylinder 29 is rotated according to the change of magnification. Consequently, the lens support 4A fixed to the cylindrical cam 25 moves vertically to allow adjustment of back focus. Accordingly, the whole device can be made small.