Patent ID: 7667915

Claim:
A disk drive comprising: a write head configured to record data on a disk medium; a data output unit configured to output data to be recorded on the disk medium; a head amplifier configured to include a first unit for allowing a write signal which corresponds to the data from the data output unit to be output to the write head when data is recorded on the disk medium and a second unit for allowing an AC signal to be output to the write head prior to the outputting of the write signal; a controller configured to control the recording of the data; and a unit configured to output a write gate signal for instructing a data recording timing to the disk medium, wherein the second unit includes a register accessed by the controller and configured to retain data for setting the frequency of the AC signal, and a unit configured to, according to the write gate signal, allow an AC signal of a frequency which is set by the retained data in the register to be generated only during a predetermined time immediately prior to the outputting of the write signal.