Method and apparatus for determining track density during a servo-track writing operation
AssigneeWestern Digital Technologies, Inc.
InventorsRaffi Codilian, William D. Johns
Life of this patent
Estimating the term…
Abstract
Disk drives are produced having a track density that is determined during a servo-track writing operation. A plurality of calibration tracks is written onto a storage medium of a disk of a head-disk assembly at a calibration track density. The calibration track density corresponds to a portion of a nominal track density profile. An aspect of the servo performance of the head-disk assembly is measured at the calibration tracks. A selected track density profile is identified based on the measured servo performance. The plurality of tracks is written to storage medium at the selected track density profile.
Claims34
A method for manufacturing a disk drive that comprises a head-disk assembly having a disk with a storage medium, the head-disk assembly having a servo performance, the method comprising:
- writing a plurality of calibration tracks onto the storage medium at a calibration track density profile corresponding to a portion of a nominal track density profile;
- measuring the servo performance of the head-disk assembly at the calibration tracks;
- selecting a track density profile based on the measured servo performance of the head-disk assembly;
- and
- writing a plurality of tracks to the storage medium of the disk at the selected track density profile.
A method for manufacturing a disk drive that comprises a head-disk assembly having a disk with a storage medium, the head-disk assembly having a servo performance, the method comprising:
- writing a plurality of calibration tracks onto the storage medium at a calibration track density profile corresponding to a portion of a nominal track density profile;
- measuring the position error signal of the head-disk assembly and the settle time of the head-disk assembly at the calibration tracks;
- identifying a density-based track density profile based on the measured position error signal of the head-disk assembly;
- determining whether the value of the measured position error signal permits reducing the average density of the density-based track density profile in order to improve the settle time of the head-disk assembly;
- selecting a track density profile based on the determining step;
- and
- writing a plurality of tracks to the storage medium of the disk at the selected track density profile.
A servo-track writer for writing a plurality of calibration tracks on a storage medium of a head-disk assembly at a calibration stepping increment and for writing a plurality of servo-tracks on the storage medium of the head-disk assembly at a selected stepping increment, the head-disk assembly comprising a read element, a write element, and an actuator, the head-disk assembly having a servo performance, the servo-track writer comprising:
- (a) a controller that processes a clock reference pattern to determine the circumferential location of the write element and that directs the write element to write the servo-tracks to the storage medium;
- (b) a servo performance measurement circuit that measures an aspect of the servo performance of the head-disk assembly and that selects a stepping increment based thereon;
- and
- (c) a head positioner circuit that comprises a positioning mechanism that imparts a step-wise movement to the actuator at a calibration stepping increment for writing the plurality of calibration tracks, and that imparts a step-wise movement to the actuator at the selected stepping increment for writing the plurality of servo-tracks to the storage medium.
A disk drive comprising:
- a head-disk assembly having a servo performance, the head disk assembly comprising:
- an actuator;
- a read element;
- a write element;
- a spindle motor;
- and
- a disk having a storage medium, the disk mounted on the spindle motor, the storage medium written by:
- writing a plurality of calibration tracks onto the storage medium at a calibration track density corresponding to a portion of a nominal track density profile;
- measuring the servo performance of the head-disk assembly at the calibration tracks;
- selecting a track density profile based on the measured servo performance of the head-disk assembly;
- and
- writing a plurality of servo-tracks to storage medium of the disk at the selected track density profile.
A disk drive comprising:
- a head-disk assembly having a servo performance, the head disk assembly comprising:
- an actuator;
- a read element;
- a write element;
- a spindle motor;
- and
- a disk having a storage medium, the disk mounted on the spindle motor, the storage medium written by:
- writing a plurality of calibration tracks onto the storage medium at a calibration track density corresponding to a portion of a nominal track density profile;
- measuring the position error signal and the settle time of the head-disk assembly at the calibration tracks;
- identifying a density-based track density profile based on the measured position error signal of the head-disk assembly;
- determining whether the value of the measured position error signal permits reducing the average density of the density-based track density profile in order to improve the settle time of the head-disk assembly;
- selecting a track density profile based on the determining step;
- and
- writing a plurality of servo-tracks to the storage medium of the disk at the selected track density profile.
Dependencies are inferred from the claim text.