Hybrid arm-position/tape-tension servo control system

摘要

Servomechanisms (58 and 60) control a takeup reel (12) and a tension arm (16) in a cassette recorder. The servomechanisms receive control signals (54 and 56) generated in accordance with respective control functions, each of which includes a respective constituent function of the difference between a commanded tension-arm position and a measured tension-arm position. In a position of the tension arm that prevails at the beginning of tape threading (Fig. 1), the constituent of the tension-arm control function that depends on this arm-position error is a relatively large contribution and gradually decreases to zero as the tension arm moves to the position that it assumes for normal recording and playback. During the same time, the the constituent of the reel-control function that depends on arm-position error begins at zero and gradually increases. Such a gradual transfer of position-error-based control suppresses tape-tension transients that would otherwise result.