Disk drive evaluating multiple vibration sensor outputs to enable write-protection
View Patent ↗A disk drive is disclosed comprising a head actuated over a disk, and control circuitry including a vibration sensor. A position error signal (PES) is generated representing a radial location of the head over the disk, and the head is servoed radially over the disk in response to the PES. A first vibration signal is generated in response to the vibration sensor, and a second vibration signal in response to the PES. The first vibration signal is combined with the second vibration signal to generate a third vibration signal, and a vibration event is detected in response to the third vibration signal.
1. A disk drive comprising:
a disk;
a head actuated over the disk; and
control circuitry including a vibration sensor, the control circuitry operable to:
generate a position error signal (PES) representing a radial location of the head over the disk;
servo the head radially over the disk in response to the PES;
generate a first vibration signal in response to the vibration sensor;
generate a second vibration signal in response to the PES;
combine the first vibration signal with the second vibration signal to generate a third vibration signal; and
detect a vibration event in response to the third vibration signal.
2. The disk drive as recited in claim 1 , wherein the control circuitry is further operable to disable writing to the disk in response to the detected vibration event.
3. The disk drive as recited in claim 1 , wherein the vibration sensor comprises an accelerometer.
4. The disk drive as recited in claim 1 , wherein the vibration sensor comprises at least one of a linear vibration sensor and a rotational vibration sensor.
5. The disk drive as recited in claim 1 , wherein the control circuitry is further operable to generate the second vibration signal by computing a variance of the PES.
6. The disk drive as recited in claim 1 , wherein the control circuitry is further operable to generate the second vibration signal by detecting when the PES exceeds a threshold.
7. The disk drive as recited in claim 6 , wherein the control circuitry is further operable to generate the second vibration signal by detecting a number of times the PES exceeds the threshold over a predetermined interval.
8. The disk drive as recited in claim 1 , wherein the control circuitry is further operable detect the vibration event when the third vibration signal exceeds a threshold.
9. The disk drive as recited in claim 1 , wherein the control circuitry is further operable to compare an output of the vibration sensor to a plurality of thresholds to generate the first vibration signal.
10. The disk drive as recited in claim 1 , wherein the control circuitry is further operable to generate the third vibration signal based on a magnitude of the first vibration signal relative to a magnitude of the second vibration signal.
11. The disk drive as recited in claim 1 , wherein the control circuitry is further operable to disable a data relocation operation when the vibration event is detected.
12. A method of operating a disk drive, the disk drive comprising a head actuated over a disk, and a vibration sensor, the method comprising:
generating a position error signal (PES) representing a radial location of the head over the disk;
servoing the head radially over the disk in response to the PES;
generating a first vibration signal in response to the vibration sensor;
generating a second vibration signal in response to the PES;
combining the first vibration signal with the second vibration signal to generate a third vibration signal; and
detecting a vibration event in response to the third vibration signal.
13. The method as recited in claim 12 , further comprising disabling writing to the disk in response to the detected vibration event.
14. The method as recited in claim 12 , wherein the vibration sensor comprises an accelerometer.
15. The method as recited in claim 12 , wherein the vibration sensor comprises at least one of a linear vibration sensor and a rotational vibration sensor.
16. The method as recited in claim 12 , further comprising generating the second vibration signal by computing a variance of the PES.
17. The method as recited in claim 12 , further comprising generating the second vibration signal by detecting when the PES exceeds a threshold.
18. The method as recited in claim 17 , further comprising generating the second vibration signal by detecting a number of times the PES exceeds the threshold over a predetermined interval.
19. The method as recited in claim 12 , further comprising detecting the vibration event when the third vibration signal exceeds a threshold.
20. The method as recited in claim 12 , further comprising comparing an output of the vibration sensor to a plurality of thresholds to generate the first vibration signal.
21. The method as recited in claim 12 , further comprising generating the third vibration signal based on a magnitude of the first vibration signal relative to a magnitude of the second vibration signal.
22. The method as recited in claim 12 , further comprising disabling a data relocation operation when the vibration event is detected.