Disk drive during self-servo writing
A disk drive self-servo writes on a storage disk. Servo bursts are self-written along a track using a transducer, a position error signal (PES) indicating repeatable runout due (RRO) for the servo bursts is determined using a reference pattern, an embedded runout correction (ERC) value is calculated based on the PES and stored in a corresponding servo sector, and then the disk drive self-writes other servo bursts.
1. A disk drive, comprising:
a disk that includes a reference pattern and tracks, wherein the reference pattern includes servo information and the tracks include servo sectors, and embedded runout correction (ERC) values compensate for repeatable runout (RRO) in the tracks;
a transducer that reads data from and writes data to the disk; and
a controller that (1) generates a position error signal (PES) using the transducer to read the reference pattern while the transducer is at a radial position, (2) self-writes a servo burst on the disk using the transducer while using the PES to position the transducer at the radial position, wherein the PES indicates the RRO for the servo burst and the transducer remains positioned at the radial position between reading the reference pattern and self-writing the servo burst, (3) calculates an ERC value for the servo burst using the PES, and (4) writes the ERC value to the disk using the transducer;
wherein the controller also (1) generates a second PES using the transducer to read the reference pattern while the transducer is at a second radial position, (2) self-writes a second servo burst on the disk using the transducer while using the second PES to position the transducer at the second radial position, wherein the servo bursts are radially offset, circumferentially staggered servo bursts, and the second PES indicates RRO for the second servo burst, and (3) calculates the ERC value for the servo bursts using the PES's; and
wherein the controller (1) generates the PES and self-writes the servo burst during a first revolution of the disk, and (2) generates the second PES and self-writes the second servo burst during a second revolution of the disk.
2. The disk drive of claim 1 , wherein the reference pattern is a temporary pattern.
3. The disk drive of claim 1 , wherein the reference pattern is circumferentially spaced spirals.
4. The disk drive of claim 1 , wherein the servo bursts define a track centerline in a servo sector.
5. The disk drive of claim 1 , wherein the controller (1) generates a second PES using the transducer to read the reference pattern while the transducer is at the radial position after self-writing the servo burst, wherein the second PES indicates RRO for the servo burst, (2) generates an interpolated PES using the PES's, and (3) calculates the ERC value using the interpolated PES.
6. The disk drive of claim 1 , wherein the controller calculates and stores the ERC values on a sector-by-sector basis for each servo sector in a track.
7. The disk drive of claim 1 , wherein the controller calculates the ERC value without reading the servo burst.
8. The disk drive of claim 1 , wherein the controller calculates the ERC value without reading a final servo pattern.
9. An apparatus comprising:
a storage media having a temporary reference pattern indicating a repeatable runout for a plurality of servo tracks; and
a controller operatively coupled to a transducer, the controller generating a position error signal using a repeatable runout corresponding to one of the plurality of tracks, using the position error signal to radially position the transducer over the track, and writing a servo burst and an embedded runout correction value for the track calculated from the position error signal.
10. The apparatus of claim 9 , wherein the controller generates the position error signal and writes the servo burst during a single revolution of the storage media.
11. The apparatus of claim 9 , wherein the controller calculates the embedded runout correction value without reading the servo burst.
12. The apparatus of claim 9 , wherein the controller calculates the embedded runout correction value without reading a final servo pattern.
13. An apparatus comprising:
a storage media having a reference pattern of circumferentially spaced spirals indicating a repeatable runout for a plurality of servo tracks; and
a controller operatively coupled to a transducer, the controller generating a position error signal using a repeatable runout corresponding to one of the plurality of tracks, using the position error signal to radially position the transducer over the track, and writing a servo burst and an embedded runout correction value for the track calculated from the position error signal.