Patent ID: 7639446
Filing Date: 2009-12-29
Classification: G11B

Abstract:
1. A disk drive device comprising: a head configured to read and write data; a disk media in which a plurality of spiral servo patterns are written as a base pattern for writing a plurality of radial servo patterns which are of a product servo pattern, each of the plurality of spiral servo patterns including a burst signal in which sync marks are inserted at predetermined intervals; a clock generating module configured to generate a servo write clock, the servo write clock being of a reference clock; and a servo write module configured to function in synchronization with the servo write clock, and to perform a self servo write process using the plurality of spiral servo patterns while moving the head on the disk media in a radial direction, the plurality of radial servo patterns being written on the disk media in the self servo write process, wherein the servo write module is configured to search a spiral servo pattern to be used as the base pattern, to measure a time interval from a time point at which a sync mark is read in the searched spiral servo pattern to a time point at which a sync mark is read in a spiral servo pattern adjacent to the searched spiral servo pattern, to adjust a phase of the servo write clock based on a difference between the measured time interval and a predetermined reference time interval, to detect a shift amount of a sync mark position in other spiral servo patterns with respect to a sync mark position in the searched spiral servo pattern to store a correction value indicating the detected shift amount in a correction table, to position the head at a target position where the radial servo pattern is written on the disk media using the searched spiral servo pattern to write predetermined servo data for the radial servo pattern at the target position, to switch the spiral servo pattern to be used as the base pattern when a radial position of the head reaches a radial position where the spiral servo pattern currently used as the base pattern and the radial servo pattern overlap each other, to obtain a correction value corresponding to a spiral servo pattern to be used as a base pattern from the table when the spiral servo pattern to be used as the base pattern is switched, and to adjust the phase of the servo write clock based on the obtained correction value.