Systems for self-servowriting in multiple portions with multiple passes per servowriting step
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 servo bursts are used to define a position on the media, trimming a first burst and writing a second burst on separate revolutions of the media 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 combination of bursts, each burst also can be trimmed and/or written in multiple passes. The overall error in position should decrease as the number of passes used to write a burst combination increases. 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 system for writing position information to a rotating medium, comprising:
a rotatable medium to store information;
a write element to write information to the rotatable medium;
a control mechanism to rotate the rotatable medium and position the write element relative to the rotatable medium; and
a machine readable medium including instructions to:
write a first servo burst during a first servowriting step of the write element over the rotatable medium;
trim a first portion of the first servo burst during a first pass of a second servowriting step of the write element;
trim a second portion of the first servo burst during a second pass of the second servowriting step of the write element;
write a second servo burst during a third pass of the second servowriting step of the write element, wherein the first servo burst and second servo burst each have a substantially common edge that can be used to determine the position of the write element during a subsequent pass over those servo bursts; and
demodulate the first portion and the second portion of the first servo burst so that written-in runout is reduced.
2. A system according to claim 1 , wherein:
the rotatable medium is selected from the group consisting of magnetic disks, optical disks, and laser-recordable disks.
3. A system according to claim 1 , wherein:
the first servo burst and second servo burst each have an edge that is positioned approximately along a track line, the track line extending circumferentially about the disk.
4. A system according to claim 1 , further comprising:
a read element to read one or both of the first servo burst and the second servo burst on a subsequent pass over the rotatable medium.
5. A system according to claim 4 , further comprising:
a read/write head containing the read element and the write element.
6. A system according to claim 5 , further comprising:
read circuitry to accept information from the read element and determine the position of the read/write head.
7. A system according to claim 1 , wherein:
the machine readable medium further includes instructions to trim the first servo burst to have a width approximately equal to the width of a track of servo data.
8. A system according to claim 1 , wherein:
the machine readable medium further includes instructions to write the first and second servo bursts in a servo wedge on the rotatable medium.
9. A system according to claim 1 , wherein the first servo burst includes a plurality of transitions, and wherein:
the instruction to trim a first portion of the first servo burst includes trimming less than all of the plurality of transitions.
10. The system of claim 1 , wherein the machine readable medium further includes instructions to average the first portion and the second portion of the first servo burst.
11. A system for writing position information to a rotating medium, comprising:
a rotatable medium to store information;
a write element to write information to the rotatable medium; and
a control mechanism to rotate the rotatable medium and position the write element relative to the rotatable medium; and
a machine readable medium including instructions to:
write a first servo burst during a first servowriting step of the write element over a rotating medium;
trim the first servo burst during a first pass of a second servowriting step of the write element;
write a first portion of a second servo burst during a second pass of the second servowriting step of the write element;
write a second portion of the second servo burst during a third pass of the second servowriting step of the write element, wherein the first servo burst and second servo burst each have a substantially common edge that can be used to determine the position of the write element during a subsequent pass over those servo bursts; and
demodulate the first portion and the second portion of the second servo burst so that written-in runout is reduced.
12. A system according to claim 11 , wherein the second burst includes a plurality of transitions, and wherein:
the write element writes the first portion of the second burst pattern by writing less than all of the plurality of transitions.
13. The system of claim 11 , wherein the machine readable medium further includes instructions to average the first portion and the second portion of the first servo burst.
14. system for writing position information to a rotating medium, comprising:
a rotatable medium to store information;
a write element to write information to the rotatable medium; and
a control mechanism adapted to rotate the rotatable medium and position the write element relative to the rotatable medium; and
a machine readable medium including instructions to:
write a first servo burst during a first servowriting step of the write element over a rotating medium;
trim at least a portion of a first servo burst during a first pass of a second servowriting step of the write element;
write at least a portion of a second servo burst during a second pass of the second servowriting step of the write element, wherein the first servo burst and second servo burst each have a substantially common edge that can be used to determine the position of the write element during a subsequent pass over those servo bursts; and
demodulate the at least a portion of the first servo burst and/or second servo burst so that written-in runout is reduced.
15. The system of claim 14 , wherein the machine readable medium further includes instructions to average the first portion and the second portion of the first servo burst.