Patent ID: 7561369

Claim:
A drive unit comprising: a recording medium; a head for writing/reading data to/from the recording medium; an actuator for making a relative movement of the head with respect to the recording medium; a signal generation circuit for, on the basis of data that is read out from the recording medium by the head, generating a position error signal at intervals of a specified sampling period, said position error signal indicating the amount of a position error of the head; a digital filter circuit in which a gain becomes effective for a setting frequency that is set; a setting changing circuit for, with a frequency of a periodically fluctuating signal component of the position error signal being used as a target frequency, controlling the setting frequency so that the setting frequency follows the target frequency within an effective frequency range of the digital filter circuit; a period changing circuit for, when the target frequency deviates from the effective frequency range, changing a sampling period of the position error signal to be supplied to the digital filter circuit so that the target frequency is converted into a frequency that falls within the effective frequency range; and a control circuit for driving the actuator on the basis of a signal that is output from the filter circuit.