| 摘要 |
PURPOSE:To generate a large amount of drive torque and to control smoothly a diaphragm by making a permanent magnet for forming a magnetic loop at a circular top bisected by the supporting spindle of a movable magnetic member and a coil for forming electric loop opposite. CONSTITUTION:The movable magnetic member 12 is contained between a driving coil 10 and the outer wall 7c of a yoke 7 so that a magnet 12h can lie between driving coils, and a fixed magnetic member 10 and the movable magnetic member 12 face each other and are conducted to the coil of the fixed magnetic member 10. Thus a magnetic pole is generated in the optical axis direction in correspondence to the current direction where a current flows in the coil, and the movable magnetic member 12 is attracted by this pole and rotated around the axis for intersecting with the optical axis O-O' with spindles 12a and 12b as a center. For instance, the movable magnetic member 12 is rotated in the direction of an arrow (a) with the spindles 12a and 12b as a center, and the swinging action of the movable magnetic member 10m swigs immediately a vane operating member 4 in the direction of an arrow gammathrough a transmission pin 12d and the motion transmitting member, drives a vane 2 in the closing direction and narrows a diaphragm, thereby suppressing the photographing light quantity to an appropriate value.
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