| 摘要 |
PURPOSE:To perform reduction and magnification smoothly by forming the cam surface that follows up the movement extent of a lens possessed by a change cam into such an arc shape that when a follower moves past the contact point of the cam follower in the stage of unmagnification the turning direction of the cam is reversed with said point as a boundary. CONSTITUTION:The cam surface 11b of a variable magnification cam 11 provided with the 1st cam surface 11a which determines the movement extent of a mirror and the 2nd cam surface 11b that follows up the movement extent of a lens is formed into a mild arc shape. It is formed to such a shape that when a follower 12 moves past the contact position in the stage of unmagnification, the turning direction of the cam is reversed at this point. More specifically, the surface 11b of the 2nd cam to be engaged with the follower 14 moving cooperatively with the mirror as the cam 11 moves clockwise around the center 13 of rotation when the follower 12 moves in any direction from said position is constituted to such a simple shape that when the cam turns in one direction the follower 14 moves in one direction. |
