| 摘要 |
PURPOSE:To rotate a zoom ring by synchronizing with a movement, by providing a helical rack in the moving direction, and using a helical gear for the zoom ring, in a variable power copying machine for moving a zoom lens diagonally against the original scanning direction when converting a magnification. CONSTITUTION:When a wire 21 wound to a driving pulley 24 is moved by rotating a motor 29, a lens base 16 is displaced. As for a rotational quantity of the motor 29, a displacement quantity of the lens base 16 is known by a photocopuler 31 for generating a pulse by synchronizing with the rotation, and when it comes to a position corresponding to the magnification, it is stopped. The position for placing an original is determined by one side face of an original placing plate, therefore, it is necessary that a zoom lens 15 moves diagnoally in the original scanning direction. A helical rack gear 36 is provided along this direction, therfore, a helical gear 35 engaged to said gear rotates, turns a zoom ring 34, moves a pin fitted into a groove hole 34', and changes the magnification. |
