TRACK PITCH DEVIATION MEASURING METHOD USING SPIRAL DC PATTERN WRITING

PROBLEM TO BE SOLVED: To provide a track pitch deviation measuring method using spiral DC pattern writing.SOLUTION: In one embodiment, the method includes the steps for using a writer of a magnetic head while moving the magnetic head in a direction almost parallel with a radial direction of a magnetic disk medium to spirally write a DC pattern on the magnetic disk medium during the rotation of the magnetic disk medium, reading the magnetic disk medium while moving the magnetic head in a direction almost parallel with the radial direction of the magnetic disk medium during the rotation of the magnetic disk medium, and calculating a track pitch interval between data tracks of the magnetic disk medium on the basis of reading of the magnetic disk medium. In another embodiment, a magnetic disk medium includes a DC spiral pattern in a radial region further outward and/or a radial region further inward than a radial region where data is recorded.