| 摘要 |
PROBLEM TO BE SOLVED: To provide an extending cam mechanism for a lens barrel, which can shorten the axial length of a cam ring while maintaining light-tightness properties for the inside of the cam ring. SOLUTION: The extending cam mechanism for the lens barrel includes: the cam ring that is rotatable and has a cam groove in its periphery; and a movable member that has a cam follower that engages with the cam groove and is movable in the direction of an optical axis. The extending cam mechanism for the lens barrel moves the movable member forward or backward in the direction of the optical axis according to the rotation of the cam ring. In the extending cam mechanism for the lens barrel, the cam groove includes a bottomed cam groove that has a pair of inclined faces separated from each other in the direction of groove width and gradually narrow the gap between them as they extend in the direction of the depth. In the cam groove, in the area near the axial end face of the cam ring, one of the pair of inclined faces, which is located at the side of the end of the cam ring, is formed as a narrow partial inclined face extending from a halfway position in the direction of the depth to the bottom part of the cam groove, and a portion from the partial inclined face to the periphery of the cam ring is formed as an inner offset face, which is located near the center of the cam groove in the direction of the groove width rather than on an extension of the partial inclined face. COPYRIGHT: (C)2011,JPO&INPIT |
