| 摘要 |
PROBLEM TO BE SOLVED: To allow the processed surface of diaphragm blades to be hardly worn even when the aperture of an iris diaphragm is repeatedly opened and closed. SOLUTION: The cylindrical surface of a hole washer 10 is provided with a groove 15 becoming one part of a spiral centered at the cylindrical axis of the cylindrical surface. A similar groove (not shown in the figure) is formed at a position symmetric to the groove 15 with the cylindrical axis as the axis of symmetry. Then, a machine screw 25a is fixed to the cylindrical surface of an inner clip washer 20 and engaged with the groove 15 so as to constitute a cam mechanism. A machine screw (not shown in the figure) is arranged at the symmetric position to the position where the screw 25a is fixed with the cylindrical axis of the washer 20 as the axis of symmetry and engaged with the groove arranged at the position being symmetric to the groove 15 so as to constitute a cam mechanism. When the screw 25a is positioned at the leftmost position, the aperture formed by the diaphragm blade 30 becomes the maximum and space between the washer 20 and the washer 10 becomes the minimum. When the screw 25a is positioned at the rightmost position, the aperture becomes the minimum and the space between the washer 20 and the washer 10 becomes the maximum.
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