| 摘要 |
PROBLEM TO BE SOLVED: To provide a cam ring and a zoom lens barrel which are superior in workability of engagement with and release from a cam groove of a follower and in strength and can avoid upsizing thereof. SOLUTION: The zoom lens barrel is provided with a lens support frame which supports a lens and has follower pins on the peripheral surface, a linear motion guide ring which is formed into a rotationally symmetrical shape with the optical axis of the lens as the center and has a linear motion guide groove parallel with the optical axis, and the cam ring having the same center as the linear motion guide ring and having a cam groove formed. The follower pins of the lens support frame are fitted to the linear motion guide groove and the cam groove, and the frame is moved in the direction of the optical axis by relative rotation of the linear motion guide groove and the cam ring around the optical axis. The cam ring is provided with at least two cylindrical parts having different diameters provided in different positions in the direction of the optical axis so as to stepwise reduce the diameter and a step part placed between the cylindrical parts, and one end of the cam groove formed in the smaller-diameter cylindrical part is opened to the step part between the cylindrical part itself and the larger-diameter cylindrical part, and the follower pins are made insertable to and removable from the cam groove through the opening. COPYRIGHT: (C)2004,JPO
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