Patent ID: 8817405

Claim:
A magnetic recording disk drive comprising: a rotatable magnetic recording disk having a magnetic recording layer, the recording layer having a plurality of radially-spaced tracks, each track having circumferentially spaced servo sectors containing synchronization (sync) marks, wherein the servo sectors in each track are generally aligned circumferentially with the servo sectors in adjacent tracks to form servo sections that extend generally radially across the tracks, and wherein some of the sync marks in some of the servo sectors are circumferentially misaligned with their radially adjacent sync marks; a read head for reading the sync marks in the servo sectors as the disk rotates; an actuator connected to the head for causing the head to seek radially from one track to another track; a sync mark detector coupled to the read head for sampling the sync marks; a servo clock for generating a variable frequency to the sync mark detector as the read head crosses a servo section during a seek, the variable frequency being in response to the sync mark circumferential misalignment and to the radial position of the read head as it crosses a servo section during a seek.