| 摘要 |
PROBLEM TO BE SOLVED: To make the shape of an aperture near to a right circle within a range from an open aperture state to an optional aperture state without increasing the number of blade member. SOLUTION: The light quantity adjusting device has a plurality of blade members and changes the size of the aperture through which luminous flux passes by turning the plurality of blade members. The circular arc-shaped inner edge part related to formation of the aperture, of the plurality of blade members is formed of a base inner edge part 1a near to the turning shaft of the blade member, a tip inner edge part 1b far from the turning shaft, a middle inner edge part 1c in the middle of both of them, a tip boundary inner edge part 1e connected to an inner edge part which is not related to the formation of a diaphragm aperture from the tip inner edge part, and a base boundary inner edge part 1d connected to the inner edge which is not related to the formation of the diaphragm aperture from the base inner edge part. COPYRIGHT: (C)2008,JPO&INPIT
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