Patent ID: 7804659

Claim:
A disk drive comprising: a disk medium on which spiral servo patterns are recorded; a head including a read head which reads data from the disk medium and a write head which writes data to the disk medium; a head moving unit which moves the head radially over the disk medium; a unit which reproduces burst signals of a particular shape from the spiral servo patterns read by the read head while the head is scanning circumferential regions on the rotating disk medium which correspond to concentric tracks; a generator which generates position data associating servo burst signals contained in concentric servo patterns constituting the concentric tracks with the burst signals of the particular shape; a position error calculating unit which uses the position data to perform a position error calculation required to position the head on one of the concentric tracks; and a controller which uses a result of the calculation performed by the position error calculating unit to control the head moving unit and thus positioning of the head, wherein the generator divides each of the burst signals of the particular shape into a plurality of regions in a circumferential direction to generate position data associating amplitudes obtained from the respective regions with position signals A and B reproduced from the servo burst signals and used to calculate an error in a position with respect to a center line of each of the concentric tracks and position signals C and D reproduced from the servo burst signals and used to calculate an error in a position with respect to an adjacent track boundary.