Servo track having periodic frames of tone field and embedded synchronization marks
View Patent ↗Methods and systems for sensing a position of a transducer head with respect to a storage medium. One method includes generating a read signal from a servo track stored on a magnetic storage medium. The servo track includes servo frames of magnetic flux transitions forming detectable servo marks, the servo marks forming a tone field of repeating servo marks oriented at a first azimuth angle and a mid-frame synchronization mark incorporated within the tone field, wherein the tone field provides a metric reference for dimensional measurements between features within the servo frame(s). The number of servo marks in the tone field of each servo frame along a longitudinal direction of the servo track before the mid-frame synchronization mark and after the mid-frame synchronization mark varies with lateral position.
1. A magnetic storage medium including a longitudinal servo track, the servo track comprising:
magnetic flux transitions forming detectable servo marks, the servo marks forming a tone field of repeating servo marks oriented at a first azimuth angle, whereby the tone field provides a metric reference for dimensional measurements between features of the servo track, wherein the tone field servo marks are phase encoded with information associated with a longitudinal position of the servo track by displacing selective servo marks of the tone field to create longitudinal characters; and
servo frames of the tone field having a mid-frame synchronization mark incorporated within the tone field, wherein
the mid-frame synchronization mark is distinguishable from the tone field, and for each servo frame the number of servo marks in the tone field of the servo frame along a longitudinal direction of the servo track before the mid-frame synchronization mark and after the mid-frame synchronization mark varies with lateral position of the servo track.
2. The magnetic storage medium of claim 1 , wherein the servo frames are separated by a detectable feature.
3. The magnetic storage medium of claim 2 , wherein the detectable feature includes an erased band.
4. The magnetic storage medium of claim 2 , wherein the detectable feature includes a uniquely identifiable servo mark.
5. The magnetic storage medium of claim 1 , wherein the mid-frame synchronization mark has a magnetic flux transition spacing different than the tone field.
6. The magnetic storage medium of claim 1 , wherein the mid-frame synchronization mark includes an erased band of the servo track.
7. The magnetic storage medium of claim 1 , wherein the mid-frame synchronization mark differs in magnetic flux characteristic and azimuth angle from the tone field of servo marks.
8. The magnetic storage medium of claim 1 , wherein the mid-frame synchronization mark is at a second azimuth angle, and the first azimuth angle and the second azimuth angle are equal but opposite to a lateral dimension of the magnetic storage medium.
9. The magnetic storage medium of claim 1 , wherein the mid-frame synchronization mark is at a second azimuth angle, and the first azimuth angle and the second azimuth angle are different, but not equal and opposite to the lateral dimension of the magnetic storage medium.
10. The magnetic storage medium of claim 1 , wherein the tone field flux transitions and the mid-frame synchronization mark flux transition are at different azimuth angles and occupy simultaneously the same longitudinal and lateral dimension of the servo frame.
11. The magnetic storage medium of claim 1 , wherein the tone field servo marks are encoded with information.
12. The magnetic storage medium of claim 11 , wherein the information is associated with a longitudinal position of the servo track.
13. The magnetic storage medium of claim 1 , further including multiple servo tracks spaced laterally across the magnetic storage medium to define data bands therebetween.
14. The magnetic storage medium of claim 13 , wherein the multiple servo tracks are indexed to adjacent data bands.
15. The magnetic storage medium of claim 13 , wherein the data bands are defined between the servo tracks.
16. The magnetic storage medium of claim 1 , wherein the servo marks of the tone field are disposed having a uniform distance therebetween.
17. A magnetic storage medium including a longitudinal servo track, the servo track comprising:
magnetic flux transitions forming detectable servo marks, the servo marks forming a tone field of repeating servo marks oriented at a first azimuth angle, whereby the tone field provides a metric reference for dimensional measurements between features of the servo track, wherein the tone field servo marks are phase encoded with information associated with a longitudinal position of the servo track by displacing selective servo marks of the tone field to create longitudinal characters.
18. The magnetic storage medium of claim 17 , wherein the servo track further includes servo frames of the tone field having a mid-frame synchronization mark incorporated within the tone field, wherein
the mid-frame synchronization mark is distinguishable from the tone field, and for each servo frame the number of servo marks in the tone field of the servo frame along a longitudinal direction of the servo track before the mid-frame synchronization mark and after the mid-frame synchronization mark varies with lateral position.
19. The magnetic storage medium of claim 18 , wherein the servo frames are separated by a detectable feature.
20. The magnetic storage medium of claim 18 , wherein the mid-frame synchronization mark differs in magnetic flux characteristic and azimuth angle from the tone field of servo marks.
21. The magnetic storage medium of claim 18 , wherein the mid-frame synchronization mark is at a second azimuth angle, and the first azimuth angle and the second azimuth angle are equal but opposite to a lateral dimension of the magnetic storage medium.
22. The magnetic storage medium of claim 18 , wherein the mid-frame synchronization mark is at a second azimuth angle, and the first azimuth angle and the second azimuth angle are different, but not equal and opposite to the lateral dimension of the magnetic storage medium.
23. The magnetic storage medium of claim 17 , wherein the information is associated with a longitudinal position of the servo track.
24. A magnetic storage medium including a longitudinal servo track, the servo track comprising:
magnetic flux transitions forming detectable servo marks, the servo marks forming a tone field of repeating servo marks oriented at a first azimuth angle, whereby the tone field provides a metric reference for dimensional measurements between features of the servo track, wherein:
the tone field servo marks are phase encoded with information associated with a longitudinal position of the servo track by displacing selective servo marks of the tone field to create longitudinal characters;
the servo track further includes servo frames of the tone field having a mid-frame synchronization mark at a second azimuth angle incorporated within the tone field, wherein the first azimuth angle and the second azimuth angle different,
the mid-frame synchronization mark is distinguishable from the tone field, and
for each servo frame the number of servo marks in the tone field of the servo frame along a longitudinal direction of the servo track before the mid-frame synchronization mark and after the mid-frame synchronization mark varies with lateral position of the servo track.
25. The magnetic storage medium of claim 24 , wherein the mid-frame synchronization mark is at a second azimuth angle, and the first azimuth angle and the second azimuth angle are equal but opposite to a lateral dimension of the magnetic storage medium.
26. The magnetic storage medium of claim 24 , wherein the mid-frame synchronization mark is at a second azimuth angle, and the first azimuth angle and the second azimuth angle are different, but not equal and opposite to the lateral dimension of the magnetic storage medium.