Granted Patent B1

US 9,076,490 · App. 13/712,905 · Granted Jul 7, 2015

Abstract

Claims (141)

1. A disk drive comprising:

a disk comprising a plurality of spiral seed tracks;

a head; and

control circuitry operable to:

position the head at a first radial location over the disk;

servo the head over the disk in response to the spiral seed tracks starting from the first radial location in order to write a first spiral servo track on the disk;

position the head at a second radial location over the disk different from the first radial location;

servo the head over the disk in response to the spiral seed tracks starting from the second radial location in order to write a second spiral servo track on the disk; and

configure a difference between the first and second radial locations according to:

Δ

⁢

⁢

r

=

v

f

⁢

T

N

*

v

s

v

s

+

v

f

where:

Δr represents the difference between the first and second radial locations;

v f represents a velocity of the head while writing the first and second spiral servo tracks;

T represents a number of servo samples in a revolution of the disk;

N represents a number of spiral servo tracks written to the disk; and

v s represents a velocity of a trajectory of the spiral seed tracks.

2. The disk drive as recited in claim 1 , wherein a radial trajectory of the spiral seed tracks is opposite a radial trajectory of the spiral servo tracks.

3. The disk drive as recited in claim 1 , wherein:

when writing the first spiral servo track to the disk the control circuitry is operable to servo the head over the disk by updating at least one servo state at a servo sample rate; and

prior to writing the second spiral servo track to the disk the control circuitry is operable to shift a phase of the servo sample rate.

4. The disk drive as recited in claim 3 , wherein the difference between the first and second radial locations and the shift of the phase of the servo sample rate results in a substantially consistent servo sampling relative to the spiral seed tracks.

5. The disk drive as recited in claim 3 , wherein

the shift of the phase of the servo sample rate is configured according to:

Δ

⁢

⁢

r

v

s

6. A method of operating a disk drive comprising a head actuated over a disk comprising a plurality of spiral seed tracks, the method comprising:

positioning the head at a first radial location over the disk;

servoing the head over the disk in response to the spiral seed tracks starting from the first radial location in order to write a first spiral servo track on the disk;

positioning the head at a second radial location over the disk different from the first radial location;

servoing the head over the disk in response to the spiral seed tracks starting from the second radial location in order to write a second spiral servo track on the disk; and

configuring a difference between the first and second radial locations according to:

Δ

⁢

⁢

r

=

v

f

⁢

T

N

*

v

s

v

s

+

v

f

where:

Δr represents the difference between the first and second radial locations;

v f represents a velocity of the head while writing the first and second spiral servo tracks;

T represents a number of servo samples in a revolution of the disk;

N represents a number of spiral servo tracks written to the disk; and

v s represents a velocity of a trajectory of the spiral seed tracks.

7. The method as recited in claim 6 , wherein a radial trajectory of the spiral seed tracks is opposite a radial trajectory of the spiral servo tracks.

8. The method as recited in claim 6 , wherein:

when writing the first spiral servo track to the disk further comprising servoing the head over the disk by updating at least one servo state at a servo sample rate; and

prior to writing the second spiral servo track to the disk further comprising shifting a phase of the servo sample rate.

9. The method as recited in claim 8 , wherein the difference between the first and second radial locations and the shift of the phase of the servo sample rate results in a substantially consistent servo sampling relative to the spiral seed tracks.

10. The method as recited in claim 8 , wherein

the shift of the phase of the servo sample rate is configured according to:

Δ

⁢

⁢

r

v

s

11. A disk drive comprising:

a disk comprising a plurality of spiral seed tracks;

a head; and

control circuitry operable to:

position the head at a first radial location over the disk;

servo the head over the disk in response to the spiral seed tracks starting from the first radial location in order to write a first spiral servo track on the disk;

position the head at a second radial location over the disk different from the first radial location; and

servo the head over the disk in response to the spiral seed tracks starting from the second radial location in order to write a second spiral servo track on the disk,

wherein a radial trajectory of the spiral seed tracks is opposite a radial trajectory of the spiral servo tracks.

12. A method of operating a disk drive comprising a head actuated over a disk comprising a plurality of spiral seed tracks, the method comprising:

positioning the head at a first radial location over the disk;

servoing the head over the disk in response to the spiral seed tracks starting from the first radial location in order to write a first spiral servo track on the disk;

positioning the head at a second radial location over the disk different from the first radial location; and

servoing the head over the disk in response to the spiral seed tracks starting from the second radial location in order to write a second spiral servo track on the disk,

wherein a radial trajectory of the spiral seed tracks is opposite a radial trajectory of the spiral servo tracks.

13. A disk drive comprising:

a disk comprising a plurality of spiral seed tracks;

a head; and

control circuitry operable to:

position the head at a first radial location over the disk;

servo the head over the disk in response to the spiral seed tracks starting from the first radial location in order to write a first spiral servo track on the disk;

position the head at a second radial location over the disk different from the first radial location; and

servo the head over the disk in response to the spiral seed tracks starting from the second radial location in order to write a second spiral servo track on the disk,

wherein:

when writing the first spiral servo track to the disk the control circuitry is operable to servo the head over the disk by updating at least one servo state at a servo sample rate; and

prior to writing the second spiral servo track to the disk the control circuitry is operable to shift a phase of the servo sample rate according to:

Δ

⁢

⁢

r

v

s

where:

Δr represents a difference between the first and second radial locations; and

v s represents a velocity of a trajectory of the spiral seed tracks.

14. A method of operating a disk drive comprising a head actuated over a disk comprising a plurality of spiral seed tracks, the method comprising:

positioning the head at a first radial location over the disk;

servoing the head over the disk in response to the spiral seed tracks starting from the first radial location in order to write a first spiral servo track on the disk;

positioning the head at a second radial location over the disk different from the first radial location; and

servoing the head over the disk in response to the spiral seed tracks starting from the second radial location in order to write a second spiral servo track on the disk,

wherein:

when writing the first spiral servo track to the disk the method further comprises servoing the head over the disk by updating at least one servo state at a servo sample rate; and

prior to writing the second spiral servo track to the disk the method further comprises shifting a phase of the servo sample rate according to:

Δ

⁢

⁢

r

v

s

where:

Δr represents a difference between the first and second radial locations; and

v s represents a velocity of a trajectory of the spiral seed tracks.

Assignments (6)