Patent ID: 6853512

Claim:
A data storage device comprising: a storage medium for storing user data and servo data; a head for writing and reading said user data at a predetermined access location on said storage medium, and for reading said servo data; signal output means for employing said servo data read by said head to output a position shift signal that represents the distance the position of said head is shifted; a filter for receiving said position shift signal, and for obtaining an effective gain relative to a predetermined frequency that has been set; phase comparison means for comparing the phase of said position shift signal with the phase of a signal output by said filter; frequency setting means for changing said predetermined frequency based on the comparison results obtained by said phase comparison means; control means for, based on said position shift signal and said signal output by said filter, generating a control signal in order to position said head at said access location, and for outputting said control signal; and a motor for driving said head based on said control signal.