Granted Patent B1

US 8,891,192 · App. 13/678,495 · Granted Nov 18, 2014

Abstract

Claims (41)

1. A disk drive comprising:

a disk comprising a plurality of tracks;

a head actuated over the disk; and

control circuitry operable to:

read a target track to generate a read signal;

inject a noise signal into the read signal to generate a noisy read signal;

measure an off-track read capability (OTRC) based on the noisy read signal by measuring an OTRC metric at a plurality of radial offsets for the head relative to a center of the target track; and

adjust a parameter of the disk drive based on the OTRC.

2. The disk drive as recited in claim 1 , wherein the control circuitry is further operable to:

configure an amplitude of the noise signal to a target amplitude; and

after configuring the amplitude of the noise signal, adjust the parameter of the disk drive until the OTRC reaches a target threshold.

3. The disk drive as recited in claim 2 , wherein the parameter of the disk drive comprises a fly height of the head.

4. The disk drive as recited in claim 3 , wherein the control circuitry is further operable to:

scan for defects on the disk while the head is operating based on a first fly height; and

after scanning for defects, adjust the fly height until the OTRC reaches the target threshold.

5. The disk drive as recited in claim 4 , wherein the adjusted fly height is higher than the first fly height to reduce a probability of the head contacting an asperity on the disk during a normal read operation of the disk drive.

6. The disk drive as recited in claim 4 , wherein prior to defect scanning the disk the control circuitry is further operable to calibrate the first fly height by:

increasing the amplitude of the noise signal; and

adjusting the fly height until the OTRC reaches the target threshold.

7. The disk drive as recited in claim 6 , wherein after scanning for defects the control circuitry is further operable to:

decrease the amplitude of the noise signal; and

adjust the fly height until the OTRC reaches the target threshold.

8. A method of operating a disk drive, the disk drive comprising a disk comprising a plurality of tracks, and a head actuated over the disk, the method comprising:

reading a target track to generate a read signal;

injecting a noise signal into the read signal to generate a noisy read signal;

measuring an off-track read capability (OTRC) based on the noisy read signal by measuring an OTRC metric at a plurality of radial offsets for the head relative to a center of the target track; and

adjusting a parameter of the disk drive based on the OTRC.

9. The method as recited in claim 8 , further comprising:

configuring an amplitude of the noise signal to a target amplitude; and

after configuring the amplitude of the noise signal, adjusting the parameter of the disk drive until the OTRC reaches a target threshold.

10. The method as recited in claim 9 , wherein the parameter of the disk drive comprises a fly height of the head.

11. The method as recited in claim 10 , further comprising:

scanning for defects on the disk while the head is operating based on a first fly height; and

after scanning for defects, adjusting the fly height until the OTRC reaches the target threshold.

12. The method as recited in claim 11 , wherein the adjusted fly height is higher than the first fly height to reduce a probability of the head contacting an asperity on the disk during a normal read operation of the disk drive.

13. The method as recited in claim 11 , wherein prior to defect scanning the disk the method further comprises calibrating the first fly height by:

increasing the amplitude of the noise signal; and

adjusting the fly height until the OTRC reaches the target threshold.

14. The method as recited in claim 13 , wherein after scanning for defects the method further comprising:

decreasing the amplitude of the noise signal; and

adjusting the fly height until the OTRC reaches the target threshold.

Assignments (8)