| 摘要 |
PROBLEM TO BE SOLVED: To provide a light quantity adjusting device which can selectively actuate a light quantity adjusting means to three positions in a non-energized state and has a wide light quantity adjusting area. SOLUTION: By providing a magnetic substance which increases a holding force at a third position where the smallest holding force is generated out of three magnetic balance points formed of magnets formed in a columnar shape and having two-divided polarities by NS two poles in a radial direction, and a magnetic yoke being a cylinder and having a C-shaped cross section formed by cutting a part of the side surface of the cylinder, the holding force acting on the three magnetic balance points is made uniform, and the light quantity adjusting means takes three stop positions in a state that energization to an electromagnetic coil is interrupted. COPYRIGHT: (C)2010,JPO&INPIT |
