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 method for writing a longitudinal servo track on a magnetic storage medium, comprising:
moving a magnetic storage medium in a longitudinal direction relative to a first recording element and a second recording element, wherein the first recording element and the second recording element are aligned along the longitudinal direction and are oriented at different azimuth angles;
generating pulses in the first recording element and the second recording element to write servo frames forming a servo track, wherein within each servo frame the first recording element writes a tone field of repeating servo marks and the second recording element overwrites a portion of the tone field with a mid-frame synchronization mark such that the number of servo marks in the tone field of each servo frame along the longitudinal direction of the servo track before the mid-frame synchronization mark and after the mid-frame synchronization mark varies with lateral position, wherein the first recording element writes a start-frame synchronization mark associated with a beginning of each servo frame and the position of the mid-frame synchronization mark written by the second recording element is controlled by reading the tone field and start-frame synchronization mark written by the first recording element.
2. The method of claim 1 , wherein at least one of the mid-frame synchronization mark and the start-frame synchronization mark include a servo mark distinguishable from the tone field.
3. The method of claim 1 , wherein at least one of the mid-frame synchronization mark and the staff-frame synchronization mark include an erased region of the servo track.
4. The method of claim 1 , further including providing multiple first write elements and multiple second write elements configured to write multiple servo tracks laterally across a magnetic storage medium.
5. The method of claim 1 , wherein the different azimuth angles are equal but opposite to a lateral dimension of the magnetic storage medium.
6. The method of claim 1 , wherein the azimuth angles are different, but not equal and opposite to the lateral dimension of the magnetic storage medium.
7. The method of claim 1 , wherein the tone field and the mid-frame synchronization mark are written at different azimuth angles and occupy simultaneously the same longitudinal and lateral dimension of the servo frame.
8. The method of claim 1 , wherein the tone field and start-frame synchronization mark written by the first recording element is read by a read transducer disposed in close proximity to the second recording element.
9. The method of claim 1 , wherein the tone field and start-frame synchronization mark written by the first recording element is read by a read transducer that is fabricated on a shared magnetic shield with the second recording element.
10. The method of claim 1 , wherein the tone field servo marks are at a known pitch.
11. The method of claim 1 , wherein the tone field servo marks are encoded with information.
12. The method of claim 11 , wherein the information is associated with a longitudinal position of the servo frame.
13. The method of claim 12 , wherein the tone field servo marks are modulated to form tone field intervals that are symmetrical about the start-frame synchronization mark.
14. A method for writing a longitudinal servo track on a magnetic storage medium, comprising:
moving a magnetic storage medium in a longitudinal direction relative to a first recording element and a second recording element, wherein the first recording element and the second recording element are aligned along the longitudinal direction and are oriented at different azimuth angles;
generating pulses in the first recording element and the second recording element to write servo frames forming a servo track, wherein within each servo frame the first recording element writes a tone field of repeating servo marks and the second recording element overwrites a portion of the tone field with a mid-frame synchronization mark such that the number of servo marks in the tone field of each servo frame along the longitudinal direction of the servo track before the mid-frame synchronization mark and after the mid-frame synchronization mark varies with lateral position, wherein the tone field servo marks are phase encoded with information associated with a longitudinal position of the servo frame by displacing selective servo marks of the tone field to create longitudinal characters.