| 摘要 |
A lens-barrel cam mechanism includes first and second ring members and cam grooves and cam followers formed on the ring members. A single groove/follower set (C17s, 17s), and a groove/follower group (C17f1, 17cf1, C17r1, 17cr1), including front (C17f1, 17cf1) and rear (c17r1, 17cr1) groove/follower sets are at different positions in the optical axis direction, and at different positions in a circumferential direction. The cam groove (C17s) of the single groove/follower set (C17s, 17s) intersects those of the groove/follower group (C17f1, 17cf1, C17r1, 17cr1), and condition (a) and/or (b) are satisfied: <SL> <LI>(a) the cam groove (C17s) of the single groove/follower set (C17s,17s) is wider than that of the groove/follower group (C17f1, 17cf1, C17r1, 17cr1), and <LI>(b) an interval (angle) ( r 1, r 2, r 3) between the cam groove (C17s) of the single groove/follower set (C17s, 17s) and that of the front groove/follower set (C17f, 17cf1) and an interval (angle) ( q 1, q 2, q 3) between the cam groove (C17s) of the single groove/follower set (C17s, 17s) and that of the rear groove/follower set (C17r1, 17cr1) in the circumferential direction are different. </SL> |
