Method of controlling electromagnetic actuator in a camera, and actuator controllable thereby

Abstract

To control an electromagnetic actuator of the type having an armature movable in a magnetic field and means for urging the armature toward a rest position, a series of electrical pulses are applied to the actuator by a control circuit, the frequency of the pulses being above the cutoff frequency of the actuator, the position of the actuator being controlled by the duty cycle of the pulses. In a preferred embodiment, the actuator controls a shutter/aperture, the aperture size being determined by the duty cycle of the pulses, and the shutter time being controlled by the number of pulses applied to the actuator. An actuator controlled by the control circuit is of the type having a planar coil on an armature, mounted for movement in the plane of the coil in a magnetic field. To reduce friction and simplify construction, the armature is mounted on a flexure spring which urges the armature toward its initial position and also serves as a conductor to provide current to the armature.

Dependencies are inferred from the claim text.