Patent ID: 7663827

Claim:
A method of initializing a perpendicular magnetic recording medium in which a magnetic field having a magnetic field strength Hex is applied to a perpendicular magnetic recording medium having a magnetic layer having a coercive force Hc to initialize the magnetic layer, the method comprising: generating, using a magnetic field generating device which has a pair of magnetic poles including two magnetic poles placed on a same surface side of the perpendicular magnetic recording medium, a flux loop of a demagnetization magnetic field having magnetic field lines parallel to a circumferential direction of the perpendicular magnetic recording medium by the pair of magnetic poles; applying the demagnetization magnetic field to the perpendicular magnetic recording medium along the circumferential direction of the perpendicular magnetic recording medium to alternating-current-demagnetize the perpendicular magnetic recording medium by moving the perpendicular magnetic recording medium in the circumferential direction relative to the magnetic field generating device to make the magnetic layer of the perpendicular magnetic recording medium pass under the flux loop; controlling a magnetic field strength HexP of the demagnetization magnetic field in a direction parallel to the medium surface so that HexP>1.3×Hc; and controlling a magnetic field strength HexV of the demagnetization magnetic field in a direction perpendicular to the medium surface so that HexV<Hc.