| 摘要 |
PURPOSE:To adjust the quantity of light more accurately when a stop is almost closed by slanting the lengthwise center line of the guide pin oblong hole of a stop link lever at a constant angle to a straight line which connect the center of the stop and the center of rotation of a turning pin to each other. CONSTITUTION:When the turning pin 12 moves from an open aperture state up to an angle alpha1 which is a half as large as a turnable angle, the stop link lever 13 turns from a point A to a point B and the angle of movement becomes beta1. When the pin moves by an angle alpha2(alpha1=alpha2), the stop link lever 13 turns from the point B to a point C by an angle beta2. In this case, beta1>beta2. Similarly, when the pin 12 turns by alpha2/2 from the state shown in a figure (b) during the movement from the figure (b) to a figure (c), the turning angle of the stop link lever 13 is larger when the pin 12 further rotates by alpha2/2. Namely, variation in stop area to the turning angle of the turning pin 12 decreases as the stop is closed more as more to zero.
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