| 摘要 |
PROBLEM TO BE SOLVED: To effectively restrain an increase in required operational energy associated with the housing operation of a lens group by compensating with simple constitution an increase in rotational torque when shifting the lens group from a photographic state to a collapsible state. SOLUTION: A cam barrel 5 is provided with each of a 1st group cam 5a and a 2nd group cam 5b, and a 1st group lens system 2 and a 2nd group lens system 3 are engaged with the 1st and the 2nd group cams 5a and 5b through a 1st group driving pin 8 and a 2nd group driving pin 9 respectively. The 1st and the 2nd group lens systems 2 and 3 are energized by a spring 10 and receive biasing force in directions opposite to each other along an optical axis direction. In the 1st and the 2nd group cams 5a and 5b, the angle of the cam near a housing start position where the power of the spring is small is increased and consecutively decreased in accordance with an increase in the power of the spring, so that the angle of the cam may be minimum near the housing position where the power of the spring is maximum. COPYRIGHT: (C)2004,JPO |
