| 摘要 |
At least a pair of light amount adjusting plates is allocated at peripheral side rim portions of a light path through which light from a light source is projected. These light amount adjusting plates are drivable between a narrow-down position in which they enter into the light path and a retreat position in which they retreat to outside of the light path. A restriction member such as a stopper member restricts a rotation of the light amount adjusting plate at the retreat position, and a holding unit holds the light amount adjusting plate to this restriction member. The restriction member blocks a predetermined angle or further rotation of the light amount adjusting plate, and the holding unit, such as a spring or a magnet, biases the light amount adjusting plate to the restriction member.
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