Electromagnetically driven diaphragm device

摘要

In the disclosed diaphragm device, an electromagnetic unit is composed of two opposing sets of circularly arranged magnets poled so that opposing surfaces have the same polarity, a rotary member carrying an electromagnetic coil that moves the rotary member in response to current therethrough and the field of the magnets, and diaphragm blades which are positioned between the magnet members and the rotary member and pivoted to close the aperture in response to rotation of the rotary member in one direction. When the rotary member is rotating in the closing direction, stopping means respond to an input signal and stop movement of the diaphragm blades at a particular aperture value.