| 摘要 |
<P>PROBLEM TO BE SOLVED: To allow light quantity to be adjusted quickly and precisely. <P>SOLUTION: In a light quantity adjustment device, a soft magnetic part 32 is arranged at an outside edge part of a plate part 31 of a rotary plate 3, and a back yoke 7 and a coil 6 are arranged on a plane of a cam plate 4, perpendicular to an optic axis C1, and the center position of the coil 6 in a direction of the optic axis C1 is substantially aligned with the center-of-gravity position of the soft magnetic part 32, and the back yoke 7 is arranged so as to be disposed between the coil 6 and the cam plate 4. When the plate 3 is rotated by a motor 1, aperture blades 5 are driven and guided around a dimple part 51 in the plane perpendicular to the optic axis C1. When the coil 6 is energized, a generated magnetic field allows magnetic attractive force to act on the plate 3 in a direction of the back yoke 7 to cause the cam plate 4 and the plate 3 to sandwich the aperture blades 5 in the direction of the optic axis C1, thereby increasing respective friction loads between the aperture blades 5, between the aperture blades 5 and the cam plate 4, and between the aperture blades 5 and the plate 3. <P>COPYRIGHT: (C)2013,JPO&INPIT |
