Data storage device employing triangle-like dither to spread track squeeze
A data storage device is disclosed comprising a head actuated over a disk. The head is used to read servo information from the disk and generate a position error signal (PES) representing a position of the head over the disk. A control signal is generated based on the PES and a triangle-shape dither signal, and the head is positioned over the disk using the control signal.
1. A data storage device comprising:
a disk;
a head actuated over the disk; and
control circuitry configured to:
use the head to read servo information from the disk and generate a position error signal (PES) representing a radially position of the head over the disk;
generate a control signal based on the PES and a triangle-shape dither signal; and
position the head radially over the disk using the control signal,
wherein during an access operation the triangle-shape dither signal causes the head to cross multiple servo tracks on the disk at a substantially constant velocity, thereby spreading out an effect of track squeeze of the servo tracks.
2. The data storage device as recited in claim 1 , wherein the control circuitry is further configured to generate the triangle-shape dither signal by generating a plurality of odd harmonics of a fundamental frequency of a triangle wave.
3. The data storage device as recited in claim 1 , wherein:
the disk comprises a plurality of servo sectors defining a plurality of servo tracks;
the control circuitry is further configured to position the head over a data track using the control signal in order to access the data track; and
the triangle-shape dither signal causes the data track to cross multiple of the servo tracks.
4. The data storage device as recited in claim 3 , wherein the data track is substantially non-circular relative to a rotation axis of the disk.
5. The data storage device as recited in claim 4 , wherein the triangle-shape dither signal causes the head to follow the substantially non-circular data track.
6. The data storage device as recited in claim 4 , wherein the servo tracks are substantially circular relative to a rotation axis of the disk.
7. The data storage device as recited in claim 3 , wherein the data track is substantially circular relative to a rotation axis of the disk.
8. The data storage device as recited in claim 7 , wherein the triangle-shape dither signal causes the head to follow the substantially circular data track.
9. The data storage device as recited in claim 7 , wherein the servo tracks are substantially non-circular relative to a rotation axis of the disk.
10. The data storage device as recited in claim 1 , wherein the control circuitry is further configured to write servo sectors to the disk using the control signal to define a plurality of servo tracks, wherein the triangle-shape dither signal causes each servo track to be substantially non-circular relative to a rotation axis of the disk.
11. The data storage device as recited in claim 10 , wherein the control circuitry is further configured to position the head over a data track in order to access the data track, wherein the triangle-shape dither signal causes the data track to cross multiple of the servo tracks.
12. A data storage device comprising:
a disk;
a head actuated over the disk; and
control circuitry configured to:
generate a triangle-shape dither signal; and
write servo sectors to the disk using the triangle-shape dither signal to define a plurality of servo tracks, wherein the triangle-shape dither signal causes each servo track to be substantially non-circular relative to a rotation axis of the disk,
wherein during an access operation the triangle-shape dither signal causes the head to cross multiple of the servo tracks at a substantially constant velocity, thereby spreading out an effect of track squeeze of the servo tracks.
13. The data storage device as recited in claim 12 , wherein the control circuitry is further configured to generate the triangle-shape dither signal by generating a plurality of odd harmonics of a fundamental frequency of a triangle wave.
14. The data storage device as recited in claim 12 , wherein the control circuitry is further configured to:
generate a control signal based on the triangle-shape dither signal; and
position the head over a data track using the control signal in order to access the data track, wherein the triangle-shape dither signal causes the data track to cross multiple of the servo tracks.
15. The data storage device as recited in claim 14 , wherein the data track is substantially circular relative to a rotation axis of the disk.
16. The data storage device as recited in claim 14 , wherein the data track is substantially non-circular relative to a rotation axis of the disk.
17. A data storage device comprising:
a disk;
a head actuated over the disk; and
a means for positioning the head radially over the disk based on a triangle-shape dither signal,
wherein during an access operation the triangle-shape dither signal causes the head to cross multiple servo tracks on the disk at a substantially constant velocity, thereby spreading out an effect of track squeeze of the servo tracks.
18. The data storage device as recited in claim 17 , further comprising a means for writing servo sectors to the disk while positioning the head over the disk based on the triangle-shape dither signal.
19. The data storage device as recited in claim 17 , further comprising a means for accessing the disk while positioning the head over the disk based on the triangle-shape dither signal.