Patent ID: 8456755

Claim:
A lens barrel, comprising: a first frame formed in a substantially cylindrical shape that has at least one cam groove; and a second frame formed in a substantially cylindrical shape that has at least one cam follower to be engaged with the cam groove, wherein when the second frame rotates relative to the first frame, the second frame moves relative to the first frame in an optical axis direction, the cam follower has a first lateral surface and a second lateral surface, the first lateral surface is part of a cone or cylinder that is formed around a first center, the second lateral surface is part of a cone or cylinder that is formed around a second center, the first center and the second center are aligned in a circumferential direction of the second frame, the cam groove has a parallel portion that is substantially parallel to a circumferential direction of the first frame, an inclined portion that is inclined with respect to the circumferential direction of the first frame, and a curved portion that joins the parallel portion and the inclined portion, the inclined portion is configured so that, when the second frame rotates in one direction, the cam follower moves in only one direction along the optical axis direction, and the inclined portion and the curved portion of the cam groove are formed so that, lateral surfaces thereof are engaged with the first lateral surface and the second lateral surface of the cam follower substantially continuously.