Abstract: In one embodiment, a device for detecting the position of a head attached to a linear motor, the detection device comprises an extension member for guiding and directing flux therein. A moving coil disposed on the extension member which coil, when energized, moves along the extension for positioning the head. A magnet positioned in a spaced apart relationship with the coil for inducing a drive flux which assists in imparting the motion to the coil when the coil is energized. A first wall is positioned adjacent the linear motor. A second wall is positioned in a spaced apart relationship with the first wall.

Abstract: An improved electromagnetic camera shutter incorporating an electrically conductive shutter blade having a hole there through that is connected in series to a pair of electrically conductive springs to urge the shutter blade into a first or a second position from a compressed position between the first and the second positions.A permanent magnet having a hole there through is positioned in proximity to the shutter blade such that the shutter covers the hole in the permanent magnet when the shutter is in the first or the second position.

Abstract: A film cartridge has a folded-over tab protruding from a film egress slot in the form of a loop to be unfolded by a film leader moving outwardly through the slot and an electrically conductive patch located on the loop to be accessible for sensing only when the loop is unfolded. A sensor in a photographic camera or other film handling apparatus is positioned to detect the patch only when the loop is unfolded.

Abstract: A film cartridge has a folded-over tab protruding from a film egress slot, which is unfolded by a film leader moving outwardly through the slot. The unfolded tab provides a visible indication of film use. In an alternate embodiment, the tab is an integral extension of a light-trapping plush that lines the film egress slot.

Abstract: An electronically actuated shutter in which the location of the shutter blades are known to accurately control the aperture opening and exposure time. A Hall sensor is used to determine the position of the shutter blades.

Abstract: Exposure control apparatus is disclosed for controlling the amount of light admitted to a photosensitive surface. The apparatus comprises an electromagnetic actuator having a pair of aperture blades which are biased toward a rest position and are movable away from the rest position to define an aperture; the aperture blades also function as a shutter. A control means regulates current supplied to the actuator to control aperture size and exposure time. In order to precisely control the exposure interval, the control means includes a means for continuously sensing the position of at least one of the aperture blades.