Patent ID: 7372653

Claim:
A hard disk drive, which includes a magnetic recording medium and a write head for writing data onto the magnetic recording medium, wherein the polarity of a current flowing to the write head is reversed in accordance with the data to write the data onto the magnetic recording medium, the hard disk drive comprising: a first current source configured to supply a first current, which flows to the write head, in order to write the data onto the magnetic recording medium; a second current source configured to supply a second current, which flows to the write head, when the polarity of the first current changes; a switching circuit configured to reverse the polarities of currents flowing from the first current source and the second current source to the write head, in accordance with the data; and a control circuit configured to control after the writing data is finished so that the second current becomes approximately zero before the first current converges to approximately zero during a degauss period during which the write head is degaussed by flowing the first current to the write head with the polarity of the first current reversed while the first current is attenuated.