Apparatus for controlling and maintaining the heads to track alignment and method and apparatus to compensate steady disturbances in such an apparatus

摘要

For tracking control of magnetic heads via magnetic tracks, auxiliary servo position signals (a, b) are provided symmetrically on each side to the track center (3) and offset from each other in addition to the servo position signals (A, B) arranged offset to the track center (3). These auxiliary servo position signals (a, b) are smaller than half the track width and, when determining the position error signal PES, serve to determine the tilting of the magnetic head (1) relative to the recording track if the size is not the same. In the event of large deviations of the magnetic head (1) from the center of the track (3), these auxiliary servo position signals (a, b) can also be applied to the main servo position signals (A, B) in order to obtain a larger position error signal PES. In order to determine and compensate for uniform disturbance variables, the instantaneous values of the control signal are measured and an average value is formed therefrom, which is added to an earlier average value in certain time segments, stored and inserted into the control system as an additional control signal.