| 摘要 |
<p>PROBLEM TO BE SOLVED: To shorten a time required for transition to a minimum aperture state from a full-aperture state in amount-of-light adjustment devices.SOLUTION: An amount-of-light adjustment device according to the present invention comprises: a stationary frame member that has an opening serving as a through-hole where an optical axis passes through; an annular rotation drive member that is rotatable around the optical axis relatively to the stationary frame member; a plurality of cum grooves that are formed in the rotation drive member; a plurality of blade members that, in a periphery of the optical axis, is provided in the stationary frame member, is rotatably disposed around a shaft parallel to the optical axis, and has driven pins engaging with the cum grooves provided, respectively; and a stepping motor that rotatably drives the rotation drive member. An aperture diameter of the opening formed by respective edges of the plurality of blade members can be changed, and a shape of the cum groove is determined so that a relation between a rotation angle of the rotation drive member and the amount of change in an AV value increases a tilt as the rotation angle increases in a direction where the AV value is larger.</p> |
