Disk drive comprising slanted line servo bursts having a varying tilt angle
View Patent ↗A disk drive is disclosed comprising a disk having servo data defining a plurality of servo tracks. The servo data comprises a preamble comprising a varying length across a radius of the disk, and a plurality of slanted line servo bursts recorded at a tilt angle with respect to the preamble. The tilt angle varies across the radius of the disk commensurate with the varying length of the preamble. A position error signal (PES) is generated in response to a phase difference when reading the preamble and the slanted line servo bursts.
1. A disk drive comprising:
a disk comprising servo data defining a plurality of servo tracks, wherein the servo data comprises:
a preamble comprising a varying length across a radius of the disk; and
a plurality of slanted line servo bursts recorded at a tilt angle with respect to the preamble, wherein the tilt angle varies across the radius of the disk commensurate with the varying length of the preamble;
a head actuated radially over the disk for generating a read signal; and
control circuitry operable to:
generate a preamble read signal when the head passes over the preamble;
generate a burst read signal when the head passes over at least one of the slanted line servo bursts;
generate a position error signal (PES) in response to a phase difference between the preamble read signal and the burst read signal; and
position the head in response to the PES,
wherein:
the burst read signal comprises a periodic signal;
the burst read signal comprises a burst length representing a period of the periodic signal;
the burst length varies across the radius of the disk commensurate with the varying length of the preamble;
the tilt angle varies across the radius of the disk according to:
a tan(BL/BTP)
where BL represents the burst length and BTP represents a track pitch of the slanted line servo bursts.
2. The disk drive as recited in claim 1 , wherein:
the burst read signal comprises a burst width representing a width of one of the slanted line servo bursts; and
the burst width varies across the radius of the disk commensurate with the varying length of the preamble.
3. The disk drive as recited in claim 2 , wherein the burst width varies across the radius of the disk according to:
sin(α)·BTP
where α represents the tilt angle and BTP represents a track pitch of the slanted line servo bursts.
4. The disk drive as recited in claim 1 , wherein the servo data is recorded on the disk by fabricating magnetic slants and non-magnetic grooves.
5. The disk drive as recited in claim 1 , wherein the servo data is recorded on the disk by stamping a servo pattern on the disk using a master stamping disk.
6. A method of writing servo data to define a plurality of servo tracks on a disk of a disk drive comprising:
recording a preamble comprising a varying length across a radius of the disk; and
recording a plurality of slanted line servo bursts at a tilt angle with respect to the preamble, wherein the tilt angle varies across the radius of the disk commensurate with the varying length of the preamble,
wherein:
a burst read signal comprising a periodic signal is generated when reading at least one of the slanted line servo bursts;
the burst read signal comprises a burst length representing a period of the periodic signal;
the burst length varies across the radius of the disk commensurate with the varying length of the preamble;
the tilt angle varies across the radius of the disk according to:
a tan(BL/BTP)
where BL represents the burst length and BTP represents a track pitch of the slanted line servo bursts.
7. The method as recited in claim 6 , wherein:
the burst read signal comprises a burst width representing a width of one of the slanted line servo bursts; and
the burst width varies across the radius of the disk commensurate with the varying length of the preamble.
8. The method as recited in claim 7 , wherein the burst width varies across the radius of the disk according to:
sin(α)·BTP
where α represents the tilt angle and BTP represents a track pitch of the slanted line servo bursts.
9. The method as recited in claim 6 , wherein the servo data is recorded on the disk by fabricating magnetic slants and non-magnetic grooves.
10. The method as recited in claim 6 , wherein the servo data is recorded on the disk by stamping a servo pattern on the disk using a master stamping disk.
11. A disk for use in a disk drive, the disk comprising servo data defining a plurality of servo tracks, the servo data comprising:
a preamble comprising a varying length across a radius of the disk; and
a plurality of slanted line servo bursts recorded at a tilt angle with respect to the preamble, wherein the tilt angle varies across the radius of the disk commensurate with the varying length of the preamble,
wherein:
a burst read signal comprising a periodic signal is generated when reading at least one of the slanted line servo bursts;
the burst read signal comprises a burst length representing a period of the periodic signal;
the burst length varies across the radius of the disk commensurate with the varying length of the preamble;
the tilt angle varies across the radius of the disk according to:
a tan(BL/BTP)
where BL represents the burst length and BTP represents a track pitch of the slanted line servo bursts.
12. The disk as recited in claim 11 , wherein the servo data is recorded on the disk by fabricating magnetic slants and non-magnetic grooves.
13. The disk as recited in claim 11 , wherein the servo data is recorded on the disk by stamping a servo pattern on the disk using a master stamping disk.