Granted Patent B1

US 9,564,162 · App. 14/981,785 · Granted Feb 7, 2017

Abstract

Claims (42)

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.

Assignments (9)