Patent ID: 6879445

Claim:
A lens barrel comprising: a stationary member; a rotary input shaft which is rotatably supported by said stationary member to extend parallel to an optical axis, and includes an orthogonal surface lying in a plane orthogonal to an axis of the rotary input shaft; a manual operating ring which is rotatably supported by said stationary member, and is rotated by a rotation of said rotary input shaft via a gear mechanism; at least one optical element which is movable along the optical axis by a rotation of said manual operating ring; a hollow-cylindrical output gear having a cylindrical inner peripheral surface in which said rotary input shaft is fitted so that said hollow-cylindrical output gear can freely rotate on said rotary input shaft, and an outer gear portion which is formed on an outer peripheral surface of said hollow-cylindrical output gear to be concentric with the cylindrical inner peripheral surface, the outer gear portion serving as a part of said gear mechanism; a non-circular cross section portion formed on said rotary input shaft to be adjacent to said orthogonal surface to form at least one accommodation space between said rotary input shaft and said cylindrical inner peripheral surface; at least one ball installed in said accommodation space; and a biasing device for making said orthogonal surface and said ball come into pressing contact with each other, wherein said non-circular cross section portion is shaped so that said rotation of said rotary input shaft is transferred to said hollow-cylindrical output gear via said ball, to which said rotation of said rotary input shaft is given via said orthogonal surface, when said rotary input shaft is driven to rotate.