Patent ID: 8373934
Filing Date: 2013-02-12
Classification: G02B

Abstract:
1. A lens barrel, comprising: a zoom optical system including a plurality of lens groups each having one or more lenses, in which a focal distance is changeable between a wide-angle end and a tele end by moving the lens groups along an optical axis; a first frame moving together with a first lens group of the plurality of lens groups and which is closest to an object in the zoom optical system; and first and second cam mechanisms transmitting drive force to the first frame, wherein each of the first and second cam mechanisms includes a cam follower and a cam groove engaged with the cam follower, the cam groove including a section in which the cam follower moves when the focal distance is changed between the wide-angle end and the tele end, the section of at least one of the cam grooves of the first and second cam mechanisms includes a first section which has a predetermined gradient to a circumferential direction about the optical axis, a second section which adjoins the first section and has an absolute value of a gradient smaller than that of the first section, and a third section which adjoins the second section and has an absolute value of a gradient larger than that of the second section, and in which a sign of the gradient is the same as that of the first section, and a distance from an imaging surface to the first frame in the optical axis direction has a local minimum when the cam follower for the at least one of the cam grooves is positioned within the second section.