Methods for selective multi-pass servowriting and self-servowriting
View Patent ↗The amount of position error written into a servo burst pattern can be reduced by using additional media revolutions to write the pattern. Where the edges of two servo bursts are used to define a position on the media, trimming the first burst and writing the second burst on separate revolutions will result in a different amount of position error being written into each burst. The end result will be a reduction in the overall error in position information. In order to further reduce the position error given by a burst pair, each burst also can be trimmed and/or written in multiple passes. This description is not intended to be a complete description of, or limit the scope of, the invention. Other features, aspects, and objects of the invention can be obtained from a review of the specification, the figures, and the claims.
1. A method for writing position information to a rotatable medium, comprising:
selecting a pattern comprising a plurality of concentric tracks, wherein each concentric track is defined by a plurality of burst boundaries positioned circumferentially about a rotatable storage medium;
writing a first servo burst and a second servo burst for each burst boundary to the rotatable storage medium, wherein the first servo burst and second servo burst are written on separate passes of a write element over the rotatable storage medium, and wherein the first servo burst and second servo burst each have an edge that can be used to determine the position of the write element during a subsequent pass over those servo bursts; and
trimming the first servo burst for each burst boundary, wherein a subset of the plurality of concentric tracks is selected wherein the burst boundaries defining that subset use a separate pass of the write element to trim the first servo burst.
2. A method according to claim 1 , further comprising:
using the trimmed edge of the first servo burst and an adjacent edge of the second servo burst to determine the position of the write element.
3. A method according to claim 1 , wherein:
trimming the first servo burst includes trimming the first servo burst to have a width approximately equal to the width of a track of servo data.
4. A method according to claim 1 , wherein:
the first and second servo bursts are contained in a servo wedge on the rotatable storage medium.
5. A method according to claim 1 , wherein:
the trimmed edge of the first servo burst and an adjacent edge of the second servo burst define the position of a centerline of a data track on the rotatable storage medium.
6. A method according to claim 5 , wherein
the centerline of a data track defined by the first and second servo bursts is a member of the subset.
7. A method according to claim 1 , wherein:
writing the second servo burst occurs before trimming the first servo burst.
8. A method for writing position information to a rotatable storage medium having servo tracks and data tracks written thereon, comprising:
writing a plurality of servo tracks to a rotatable storage medium, wherein the position of each servo track is defined by an edge of a first servo burst and a complimentary edge of a second burst, and wherein the first servo burst is written in a first revolution of the rotatable storage medium, and the first burst is trimmed on a second revolution, the second servo burst also being written on the second revolution; and
writing a plurality of data tracks to a rotatable storage medium, wherein the position of each data track is defined by an edge of a third servo burst and a complimentary edge of a fourth servo burst, and wherein the third servo burst is written in a third revolution of the rotatable storage medium, the third servo burst is trimmed in a fourth revolution, and the fourth servo burst is written in a fifth revolution.
9. A method for writing position information to a rotating medium, comprising:
writing at least a portion of a first burst pattern during a first pass of a write element over a rotating medium;
trimming at least a portion of a first burst pattern during a second pass of the write element;
writing at least a portion of a second burst pattern during a third pass of the write element if the first burst pattern and second burst pattern are used to define a track centerline; and writing at least a portion of a second burst pattern during the second pass of the write element if the first burst pattern and second burst pattern are used to define a track boundary line.
10. A method for writing servo information to a magnetic disk, comprising:
writing a first servo burst during a first pass of a read/write head over a magnetic hard disk;
trimming the first servo burst during a second pass of the read/write bead, the first servo burst being trimmed so as to have a trimmed edge in about a predetermined position on the magnetic disk;
writing a second servo burst during the second pass of the read/write head if the first servo burst and second servo burst are used to define a track boundary; and
writing a second servo burst during a third pass of the read/write head if the first servo burst and second servo burst are used to define a track centerline, wherein the trimmed edge of the first servo burst and an adjacent edge of the second servo burst define a position that can be used to adjust the radial location over the disk of the read/write head during subsequent passes over those bursts.
11. A method for manufacturing a hard disk drive, comprising:
providing means for writing a first servo burst during a first pass of a read/write head over a magnetic hard disk;
providing means for trimming the first servo burst during a second pass of the read/write head, the first servo burst being trimmed so as to have a trimmed edge in about a predetermined position on the magnetic disk;
providing means for writing a second servo burst during the second pass of the read/write head if the first servo burst and second servo burst are used to define a track boundary; and
providing means for writing a second servo burst during a third pass of the read/write head if the first servo burst and second servo burst are used to define a track centerline.