IMPROVEMENTS IN PHONOGRAPH PICKUP ARMS

摘要

A pickup arm assembly for gramophone disc records comprises a pickup arm (6) pivotally mounted to a driven arm (8) movable about an axis substantially parallel to the axis of rotation of the record disc (A). The pickup arm pivot (7) carries a target (11) which coacts with a position sensor (12) mounted on the driven arm (8) to sense changes in the angle subtended between the pickup arm (6) and the driven arm (8). The position sensor (12) provides a signal corresponding to any deviation of the angle from a desired predetermined angle to operate drive means (9) for the driven arm (8) to thereby move the arm in a direction to reduce such deviation. The relationship of the position sensor (12) to the driven arm (8) may be varied in accordance with variations in the position of the driven arm (8) to reduce or illuminate tracking errors.