Data storage device measuring resonant frequency of a shock sensor by inserting the shock sensor into an oscillator circuit
View Patent ↗A data storage device is disclosed comprising a disk, a head, a shock sensor, and an oscillator circuit responsive to the shock sensor and configured to generate an oscillating signal using positive feedback. 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.
1. A data storage device comprising:
a disk;
a head;
a shock sensor;
an oscillator circuit responsive to the shock sensor and configured to generate an oscillating signal using positive feedback; and
control circuitry configured to:
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 oscillator circuit comprises a differential amplifier comprising:
an output coupled to a first terminal of the shock sensor; and
a positive input coupled to a second terminal of the shock sensor, thereby providing the positive feedback to generate the oscillating signal.
4. The data storage device as recited in claim 3 , wherein the output of the differential amplifier is further coupled to a negative input of the differential amplifier.
5. The data storage device as recited in claim 4 , wherein the output of the differential amplifier is coupled to the negative input of the differential amplifier through a negative-path amplifier circuit.
6. The data storage device as recited in claim 5 , wherein the negative-path amplifier circuit comprises:
a first current source comprising an input coupled to the first terminal of the shock sensor; and
a capacitor coupled to the first current source.
7. The data storage device as recited in claim 6 , wherein the negative-path amplifier circuit further comprises a second current source comprising an input coupled to the first terminal of the shock sensor through an inverter.
8. The data storage device as recited in claim 1 , wherein the control circuitry is further configured to:
configure a notch filter based on the detected resonant frequency of the shock sensor, wherein the notch filter is configured to filter the response of the shock sensor; and
detect the physical shock affecting the data storage device based on an output of the notch filter.
9. Control circuitry for use in a data storage device comprising a head actuated over a disk, the control circuitry comprising:
an oscillator circuit connectable to a shock sensor, wherein the oscillator circuit is operable to generate an oscillating signal representing a resonant frequency of the shock sensor; and
a shock detector configured to 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 resonant frequency of the shock sensor.
10. The control circuitry as recited in claim 9 , wherein the shock sensor is a piezoelectric sensor.
11. The control circuitry as recited in claim 9 , wherein the oscillator circuit comprises a differential amplifier comprising:
an output coupled to a first terminal of the shock sensor; and
a positive input coupled to a second terminal of the shock sensor, thereby providing positive feedback to generate the oscillating signal.
12. The control circuitry as recited in claim 11 , wherein the output of the differential amplifier is further coupled to a negative input of the differential amplifier.
13. The control circuitry as recited in claim 12 , wherein the output of the differential amplifier is coupled to the negative input of the differential amplifier through a negative-path amplifier circuit.
14. The control circuitry as recited in claim 13 , wherein the negative-path amplifier circuit comprises:
a first current source comprising an input coupled to the first terminal of the shock sensor; and
a capacitor coupled to an output of the first current source.
15. The control circuitry as recited in claim 14 , wherein the negative-path amplifier circuit further comprises a second current source comprising an input coupled to the first terminal of the shock sensor through an inverter.
16. A method of operating a data storage device, the method comprising:
detecting a resonant frequency of a shock sensor based on an oscillating signal generated by an oscillator circuit responsive to the shock sensor; 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.
17. The method as recited in claim 16 , wherein the shock sensor is a piezoelectric sensor.
18. The method as recited in claim 16 , further comprising:
connecting the shock sensor to the oscillator circuit when detecting the resonant frequency; and
disconnecting the shock sensor from the oscillator circuit when detecting the physical shock affecting the head actuated over the disk.
19. The method as recited in claim 16 , further comprising:
configuring a notch filter based on the detected resonant frequency of the shock sensor, wherein the notch filter is configured to filter the response of the shock sensor; and
detecting the physical shock affecting the data storage device based on an output of the notch filter.