Abstract: An ultrasonic ranging system for a camera includes an ultrasonic transducer responsive to a keying pulse for transmitting a frequency modulated burst of ultrasonic energy toward a subject. The leading half of the burst is a chirp whose frequency varies from a higher to a lower value; during the trailing half of the burst, the frequency remains substantially constant. The system also includes a receiver for processing an echo signal produced by the transducer on receipt of an echo within a predetermined time interval following the burst, and producing a range signal with a characteristic linearly related to the distance of a subject being photographed from the camera. A variable Q filter in the receiver filters echo signals produced by the transducer eliminates the need for a matched filter.

Abstract: A Sell-type transducer for use in an ultrasonic ranging system for a camera has a hollow base containing a floating backplate having a grooved surface in contact with the non-metallic surface of a metallized plastic diaphragm stretched across the base. A spring arrangement urges the floating backplate into engagement with the diaphragm to maintain tension thereon in the event long-term plastic flow occurs in the diaphragm. Improved side lobe suppression is achieved by progressively decreasing the depth of the grooves as the periphery is approached. Further, for repeatability, the crests of the grooves define a convex surface.

Abstract: This invention relates to a photographic apparatus which includes an exposure control system having shutter blade elements with respective selectively shaped aperture openings therethrough which, depending upon the position of the blades, symmetrically overlap over a light entering exposure opening within the camera to define an effective scene light admitting aperture. During an exposure interval, the blades move simultaneously in correspondence with each other to define a progressively variable effective aperture opening over the camera light entering opening. The exposure control system additionally includes exposure control circuitry having a photoresponsive element therein as well as means responsive to the output condition of the photoresponsive element for arresting the shutter blade movement to define a maximum effective size aperture opening as a function of a first select scene light condition during a photographic exposure interval.

Abstract: A solenoid comprising an excitation winding, a stationary armature, and a plunger disposed in cooperative arrangement such that a select partial energization of the winding operates to urge the plunger to displace laterally with respect to the winding and armature thereby stopping the plunger from further axial translation regardless of the plunger position and whereby full energization of the winding operates to urge the plunger to translate into the winding toward the armature.