| 摘要 |
PROBLEM TO BE SOLVED: To provide a feed-out cam mechanism for a zoom lens barrel, which allows a cam ring to be made small-sized without sacrificing the extent of movement of a lens group and to provide a feed-out cam mechanism which allows a cam ring to be made small-sized without sacrificing the extent of movement of a linear motion member. SOLUTION: In the feed-out cam mechanism for a zoom lens barrel, a plurality cam grooves having the same basic locus are formed in the cam ring in positions different at least in the direction of an optical axis, and each cam groove is made short-sized so as not to be present at least at a front part or a rear part and is opened to the end face of the cam ring, and a plurality of cam followers to be engaged with the plurality of cam grooves respectively are formed in a linear motion ring in positions different at least in the direction of the optical axis. Cam followers are disengaged from a part of the plurality of cam grooves in at least one of the forward movement end and the backward movement end of the linear motion ring, while the other cam followers are kept engaged with cam grooves. COPYRIGHT: (C)2004,JPO
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