A cam mechanism where one follower is temporarily disengaged from its groove

摘要

A cam mechanism has a cam ring (11) and a movable frame (8). The cam ring has at least two cam followers (8b-1, 8b-2) which engage with at least two cam grooves (11a-1, 11a-2) which have a similar reference cam diagram provided on the movable frame. The cam followers and cam grooves are each spaced along the optical axis direction and at least one of the followers (8b-1) remains engaged in a cam groove whilst the other (8b-2) is temporarily disengaged from its groove as there is a discontinuity of the groove in the Vtm area. Disengagement of the cam follower(s) with the cam groove(s) may occur during a lens zooming range of the cam grooves and the cam grooves and followers may be arranged in a circumferential direction.