| 摘要 |
PURPOSE:To position a data head at a desired position in a short time by varying an initial position in accordance with the extent of an offset after matching a servo surface signal and a data surface signal with each other. CONSTITUTION:A position error detecting circuit 9 finds a difference between the output signal of a demodulator 6 and that of a synthesizing and forming circuit 8 to output the extent of a position error between the position of a data head 2 and that of a servo head 3. An adder 10 adds the extent of the position error to a servo surface signal to output a corrected servo surface signal. This corrected servo surface signal is inputted to a position signal selection switch 11 together with the output of the circuit 8, and the switch is switched from a speed control signal to a position control signal by the output of a comparator 12. The output of the switch 11 is supplied to a compensator 13, which outputs an initial value at the time of a change from speed control to position control. This initial value is an optimum value invariably and supplied to a linear driver 17, which drives the heads 2 and 3. |
