| 摘要 |
PURPOSE:To obtain stability of the positioning operation of a magnetic head, by calculating the current position of the magnetic head by the first position signal and the second position signal and by positioning the magnetic head so that the current position becomes equal to the target position. CONSTITUTION:Position signals A and B are compared with each other by a comparing circuit 10 to discriminate whether the current position of the magnetic head is near points P0 and P1 or near points P2 and P3. Similarly, a position signal A and a polarity-inverted signal -B of a position signal B are compared with each other by a comparing circuit 11 to discriminate whether the current position of the magnetic head is near points P0 and P3 or near points P1 and P2. The exclusive OR between this discrimination signal and an output (c) of a comparing circuit 10 is obtained by an exclusive OR circuit 12. Deviations between current positions and target positions of signals (c) and (d) obtained as the result are obtained by a logical operation circuit 13, and a signal proportional to a minute deviation near the garget position P is output from a selecting circuit 16. |
