Basf Aktiengesellschaft

George J Bennett

Harold E Arns

Abraham Bejerano

An optical control system for use with a transducer positioning apparatus of a type having a lead screw coupled to the transducer head for controllably positioning the head relative to a selected track on a recording medium, wherein the lead screw is controllably rotated by a geneva mechanism that includes a geneva wheel coupled to the head screw and a geneva driver driven by a reversible d-c motor. The optical control system includes an optical disc that rotates in correspondence with the geneva driver and that has two optical tracks, one utilized in producing an error signal that varies substantially linearly with the angular position of the disc and the other utilized in producing an engagement pulse signal whenever the pin of the geneva driver is engaged in a slot in the geneva wheel. When it is desired to index the transducer head to a selected track, a pulse is coupled to the motor to drive the geneva driver in the appropriate direction, such pulse being terminated only after it has been determined that the geneva driver pin has rotated out of engagement with a slot in the geneva wheel. Thereafter, the error signal is coupled to the motor to automatically position the pin away from the geneva wheel and thereby hold the wheel, and thus the transducer head, in their respective positions.

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Huntington Beach, CA, United States of America

George J Bennett