Record carrier scanning apparatus with feedback control system for

Abstract

Apparatus for scanning a record carrier having substantially parallel recording tracks, which apparatus includes a position control system with position and velocity feedback for controlling the scanning point toward the center of a track being scanned. Such position control system produces a velocity signal (RS) indicative of the velocity of the scanning point and an error signal (RE) which, within a limited first range to either side of the track center, is proportional to the deviation from the track center. The position control system has a feedback loop which includes a control circuit for controlling the positioning of the scanning point in accordance with the error signal (RE) and the velocity signal (RS), such control circuit generating at least one substitute error signal (PE', UC') when the scanning point deviation is in a second range beyond the aforesaid first range, the substitute error signal having a sign indicative of the direction of such deviation. The control circuit provides the velocity signal (RS) and a position control signal in the feedback loop in response to either the error signal (RE) or the substitute error signal (UC', PE'), depending on whether the deviation is within the first range or the second range. The velocity control signal (RS) is independent of the magnitude of the scanning point deviation.