Systems and methods for multipass servowriting with a null burst pattern
View Patent ↗Embodiments of the present invention enables the trimming and writing of servo bursts in a null burst servo pattern as multiple portions in multiple passes while still demodulating each of the servo bursts as a single burst to obtain PES. Alternatively, the servo bursts can be trimmed and written using different currents in different passes respectively so that a gap can be created in the radial direction between the servo bursts. 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 servowriting a null burst servo pattern on a surface of a rotatable medium using a head, comprising:
positioning the head at a first radial position;
writing a first servo burst in the null burst servo pattern
positioning the head at a second radial position;
trimming the first servo burst;
writing a second servo burst in the null burst pattern while maintaining the head at the second radial position;
wherein a radial gap is formed between the first servo burst and the second servo burst;
demodulating the first and second servo burst as a single burst to obtain a position error signal.
2. The method according to claim 1 , wherein
the first servo burst and the second servo burst circumferentially overlap and are 180 degrees out of phase.
3. The method according to claim 1 , further comprising:
writing the first servo burst in a first servowriting step.
4. The method according to claim 1 , further comprising:
trimming the first servo burst in a first pass of a second servowriting step.
5. The method according to claim 1 , further comprising:
writing the second servo burst in a second pass of the second servowriting step.
6. The method according to claim 1 , wherein:
trimming the first servo burst further comprises applying an erase current to a write element of the head; and
writing a second servo burst further comprises applying a write current to the write element of the head; and
the erase current is higher than the write current.
7. The system of claim 1 , wherein the gap is narrower than a width of a read element of the read/write head.
8. A system for servowriting a null burst servo pattern, comprising:
a rotatable medium including a surface having a plurality of tracks to store the null burst servo pattern;
a write head servowrite the null burst servo pattern; and
a machine readable medium including instructions to:
position the write head at a first radial position relative to a surface of the rotatable medium for servowriting;
write a first servo burst in the null burst pattern using the write head;
position the write head at a second radial position;
trim the first servo burst using the write head;
write a second servo burst in the null burst pattern using the write head while maintaining the write head at the second radial position;
wherein a radial gap is formed between the first servo burst and the second servo burst; and
demodulate the first and second servo burst as a single burst to obtain a position error signal.
9. The system according to claim 8 wherein:
the rotatable medium is one of a magnetic disk, an optical disk, and a laser-recordable disk.
10. The system according to claim 8 , wherein:
the first servo burst and the second servo burst circumferentially overlap and are 180 degrees out of phase.
11. The method according to claim 8 , wherein the instruction to trim the first servo burst further includes instructions to apply an erase current to a write element of the head; and
wherein the instruction to write a second servo burst further includes instructions to apply a write current to the write element of the head; and
wherein the erase current is higher than the write current.
12. The system of claim 8 , wherein the gap is narrower than a width of a read element of the read/write head.
13. A system for servowriting a null burst servo pattern on a surface of a rotatable medium, comprising:
a read/write head including a write element;
a machine readable medium including instructions to:
position the write element at a first position over the surface;
write a first servo burst having a plurality of transitions in the null burst servo pattern;
position the write element at a second position overlapping the first position;
trim the first servo burst;
write a second servo burst having a plurality of transitions out of phase with the transitions of the first servo burst while maintaining the write element at the second position so that a gap is formed between the first servo burst and the second servo burst; and
demodulate the first and second servo burst to obtain a position error signal.
14. The system of claim 13 , wherein the instruction to trim the first servo burst further includes instructions to apply an erase current to a write element of the head; and
wherein the instruction to write a second servo burst further includes instructions to apply a write current to the write element of the head; and
wherein the erase current is higher than the write current.
15. The system of claim 13 , wherein the gap is narrower than a width of a read element of the read/write head.