Importance

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Abstract

A focusing mechanism for a camera includes a drive arrangement for displacing the camera lens in accordance with the contents of a counter into which the output of a pulse generator is gated during a range pulse whose duration is directly related to the distance of a subject from the camera. The pulse generator is programmed so that its pulse repetition rate matches the time-derivative of the function relating the subject distance to the lens position at which a subject is in focus. Integration of the generator output is carried out by gating the generator pulses into a counter during the range pulse such that at the trailing edge of the range pulse, the contents of the counter will be the integral of the time-derivative evaluated between the limits of the range pulse, i.e., a definite integral representative of the lens position at which a subject will be in focus when located at a distance defined by the duration of the range pulse. For fully automated operation as applied to a still camera, shutter actuation can be in response to arrival of the lens to the position at which the subject is in focus. Applied to movie cameras, the lens can track a moving subject maintaining it in focus during filming.

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First Claim