Data storage device measuring resonant frequency of a shock sensor by applying differential excitation and measuring oscillation

Patent metadata

Field	Value
Publication number	US-9564162-B1
Application number	US-201514981785-A
Country	US
Kind code	B1
Filing date	Dec 28, 2015
Priority date	Dec 28, 2015
Publication date	Feb 7, 2017
Grant date	Feb 7, 2017

Abstract

A data storage device is disclosed comprising a disk, a head, and a shock sensor comprising a first terminal and a second terminal. A first bias signal is applied signal to the first terminal of the shock sensor and a second bias signal is applied to the second terminal of the shock sensor. An oscillating signal is generated by increasing the first bias signal and decreasing the second bias signal, and a resonant frequency of the shock sensor is detected based on the oscillating signal. A physical shock affecting the head actuated over the disk is detected based on a response of the shock sensor to the physical shock and based on the detected resonant frequency of the shock sensor.

First claim

What is claimed is:

1. A data storage device comprising:
a disk;
a head;
a shock sensor comprising a first terminal and a second terminal; and
control circuitry configured to:
apply a first bias signal to the first terminal of the shock sensor and apply a second bias signal to the second terminal of the shock sensor;
generate an oscillating signal by increasing the first bias signal and decreasing the second bias signal;
detect a resonant frequency of the shock sensor based on the oscillating signal; and
detect a physical shock affecting the head actuated over the disk based on a response of the shock sensor to the physical shock and based on the detected resonant frequency of the shock sensor.

2. The data storage device as recited in claim 1 , wherein the shock sensor is a piezoelectric sensor.

3. The data storage device as recited in claim 1 , wherein the first bias signal is increased and the second bias signal is decreased by substantially the same amount.

4. The data storage device as recited in claim 3 , wherein after increasing the first bias signal and decreasing the second bias signal, an amplitude of the first bias signal substantially matches an amplitude of the second bias signal.

5. The data storage device as recited in claim 3 , wherein before increasing the first bias signal and decreasing the second bias signal, an amplitude of the first bias signal substantially matches an amplitude of the second bias signal.

6. The data storage device as recited in claim 1 , wherein:
the control circuitry comprises a differential amplifier comprising a first input coupled to the first terminal of the shock sensor and a second input coupled to the second terminal of the shock sensor; and
the first bias signal is increased and the second bias signal is decreased by substantially the same amount so that a common mode input voltage of the differential amplifier remains substantially constant.

7. The data storage device as recited in claim 6 , wherein the differential amplifier outputs the oscillating signal.

8. The data storage device as recited in claim 6 , wherein the oscillating signal is generated based on an output of the differential amplifier.

9. The data storage device as recited in claim 1 , wherein the first bias signal is a voltage and the second bias signal is a voltage.

10. Control circuitry for use in a data storage device comprising a head actuated over a disk, the control circuitry configured to:
apply a first bias signal to a first terminal of a shock sensor and apply a second bias signal to a second terminal of the shock sensor; and
generate an oscillating signal representing a resonant frequency of the shock sensor by increasing the first bias signal and decreasing the second bias signal,
wherein:
the control circuitry comprises a differential amplifier comprising a first input for coupling to the first terminal of the shock sensor and a second input for coupling to the second terminal of the shock sensor; and
the first bias signal is increased and the second bias signal is decreased by substantially the same amount so that a common mode input voltage of the differential amplifier remains substantially constant.

11. The control circuitry as recited in claim 10 , wherein the shock sensor is a piezoelectric sensor.

12. The control circuitry as recited in claim 10 , wherein the first bias signal is increased and the second bias signal is decreased by substantially the same amount.

13. The control circuitry as recited in claim 12 , wherein after increasing the first bias signal and decreasing the second bias signal, an amplitude of the first bias signal substantially matches an amplitude of the second bias signal.

14. The control circuitry as recited in claim 12 , wherein before increasing the first bias signal and decreasing the second bias signal, an amplitude of the first bias signal substantially matches an amplitude of the second bias signal.

15. The control circuitry as recited in claim 10 , wherein the differential amplifier outputs the oscillating signal.

16. The control circuitry as recited in claim 10 , wherein the oscillating signal is generated based on an output of the differential amplifier.

17. The control circuitry as recited in claim 10 , wherein the first bias signal is a voltage and the second bias signal is a voltage.

18. A method of operating data storage device comprising, the method comprising:
applying a first bias signal to a first terminal of a shock sensor and applying a second bias signal to a second terminal of the shock sensor;
generating an oscillating signal by increasing the first bias signal and decreasing the second bias signal;
detecting a resonant frequency of the shock sensor based on the oscillating signal; and
detecting a physical shock affecting a head actuated over a disk based on a response of the shock sensor to the physical shock and based on the detected resonant frequency of the shock sensor.

19. The method as recited in claim 18 , wherein the shock sensor is a piezoelectric sensor.

20. The method as recited in claim 18 , wherein the first bias signal is increased and the second bias signal is decreased by substantially the same amount.

21. The method as recited in claim 20 , wherein after increasing the first bias signal and decreasing the second bias signal, an amplitude of the first bias signal substantially matches an amplitude of the second bias signal.

22. The method as recited in claim 20 , wherein before increasing the first bias signal and decreasing the second bias signal, an amplitude of the first bias signal substantially matches an amplitude of the second bias signal.

23. The method as recited in claim 18 , wherein the first bias signal is a voltage and the second bias signal is a voltage.

Assignees

• Western Digital Tech Inc

Inventors

• Byoun Jaesoo
• Ferris Timothy A

Classifications

• G01H11/08

  using piezoelectric devices · CPC title

• G01H13/00

  Measuring resonant frequency · CPC title

• G11B5/59694 Primary

  System adaptation for working during or after external perturbation, e.g. in the presence of a mechanical oscillation caused by a shock · CPC title