Patent ID: 7394600

Claim:
A lens barrel comprising: a first frame member movable in a direction of an optical axis having a first cam follower and a second cam follower; and a second frame member formed of a cylindrical member having a pair of opening ends at both ends, which is rotatable around the optical axis relative to the first frame member, including: a first cam groove having a portion of a cam engaged with the first cam follower formed on a circumferential surface, the cam disappearing at an intermediate point of the circumferential surface, and releasing an engagement with the first cam follower on a first cam locus required for moving the first frame member in the direction of the optical axis; a first disengaged portion at which the first cam follower is not engaged from an end where the first cam groove disappears to one end of the pair of opening ends on the cam locus; a second cam groove formed on the circumferential surface, and engaged with the second cam follower while the first cam follower is not engaged with the first cam groove on a second cam locus which is different from but congruent with the first cam locus required for moving the first frame member in the direction of the optical axis; and a second disengaged portion that is not engaged with the second cam follower on the second cam locus while the first cam follower is engaged with the first cam groove, and is being cut out at an intermediate point of the second cam locus and at the other end of the pair of opening ends, wherein an engagement state is switched between an engagement of the first cam follower with the first cam groove and an engagement of the second cam follower with the second cam groove accompanied with a rotation of the second frame member.