Methods for variable 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, the rotatable storage medium having an inner diameter and an outer diameter;
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, the subset being selected based upon the proximity of each concentric track to at least one of the inner diameter and outer diameter.
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 subset further includes each first and second servo burst that defines a data track centerline.
7. A method according to claim 1 , wherein:
writing the second servo burst occurs before trimming the first servo burst.
8. A method according to claim 1 , wherein:
the subset is selected further based on the amount of runout.
9. 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 having an inner diameter and an outer diameter, 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 being written on one of the second revolution and a subsequent revolution depending on the proximity to the outer diameter; 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 on one of the fourth revolution and a subsequent revolution, depending upon the proximity to the outer diameter.
10. A method according to claim 9 , wherein:
data tracks having a fourth servo burst written on a fourth revolution are closer to the inner diameter than data tracks having a fourth servo burst written on a subsequent revolution.
11. 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 one of the second pass and a subsequent pass of the write element, depending on the proximity to an outer diameter of the rotating medium.
12. A method for manufacturing a hard disk drive, comprising:
providing means for 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, the rotatable storage medium having an inner diameter and an outer diameter;
providing means for 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
providing means for 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, the subset being selected based upon the proximity of each concentric track to at least one of the inner diameter and outer diameter.