Patent ID: 6954314

Claim:
A cam mechanism of a lens barrel, comprising: a first ring member driven to rotate about an optical axis; a second ring member which supports an optical element, and is linearly guided along said optical axis without rotating; a plurality of cam grooves having the same cam diagrams which are formed on one of said first ring member and said second ring member; and a plurality of cam followers formed on the other of said first ring member and said second ring member to be engaged in said plurality of cam grooves, respectively, wherein at least two groove/follower groups, each of which includes a front groove/follower set and a rear groove/follower set which are positioned at different positions in said optical axis direction, are positioned at different positions in a circumferential direction, each of said front groove/follower set and said rear groove/follower set including a cam groove of said plurality of cam grooves and an associated cam follower of said plurality of cam followers, wherein said cam grooves of one of said two groove/follower groups intersect said cam grooves of another of said two groove/follower groups, respectively, and wherein at least one of the following two conditions (a) and (b) is satisfied: (a) a distance in said optical axis direction between said front groove/follower set and said rear groove/follower set of one of said two groove/follower groups is different from a distance in said optical axis direction between said front groove/follower set and said rear groove/follower set of another of said two groove/follower groups, and (b) a distance in said circumferential direction between two said front groove/follower sets of said two groove/follower groups is different from a distance in said circumferential direction between two said rear groove/follower sets of said two groove/follower groups.