| 摘要 |
Briefly, according to the present invention, a lens barrel includes: a first frame member having on the inner surface thereof a female helicoid and cam grooves each of which has substantially the same lead angle as that of the female helicoid and which is deeper than the female helicoid; and a second frame member which is placed inside the first frame member and which has a male helicoid, which is engaged with the female helicoid, and cam followers which are engaged with the cam grooves. The first frame member is rotated relative to the second frame member, resulting in forward or backward movement of the second frame member.
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