Patent ID: 7859779

Claim:
A magnetic disk apparatus comprising: a magnetic disk provided with a data recording area and a servo-pattern area, the data recording area being provided by a non-magnetic area scattered with magnetic regions, the servo-pattern area including a plurality of magnetic regions each having a larger area than the magnetic regions in the data recording area and magnetized in a uniform magnetization direction; a magnetic head arranged to reciprocate radially of the magnetic disk for giving a magnetization direction to the magnetic regions in the data recording area and for reading a magnetization direction of the magnetic regions in the data recording area and of the magnetic regions in the servo-pattern area; a servo reproduction signal generator for reading the servo-pattern area with the magnetic head via an absolute-value calculation circuit so as to generate a servo reproduction signal prior to recording to or reading from the data recording area; and a magnetic head controller for performing recording to or reproducing from the data recording area by controlling the magnetic head based on the servo reproduction signal.