Disk drive detecting head touchdown by applying DC+AC control signal to fly height actuator
First Claim
Patent Images
1. A disk drive comprising:
- a disk;
a head actuated over the disk, the head comprising a dynamic fly height (DFH) actuator operable to control a fly height of the head over the disk; and
control circuitry operable to;
apply a DFH control signal to the DFH actuator to decrease the fly height of the head, wherein the DFH control signal comprises a DC component and an AC component comprising an excitation frequency;
measure a touchdown metric over an interval; and
detect the head contacting the disk in response to a frequency component of the touchdown metric at the excitation frequency,wherein the AC component comprises a periodic signal generated at a predetermined frequency high enough to attenuate a response of the DFH actuator.
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Abstract
A disk drive is disclosed comprising a head actuated over a disk, and a dynamic fly height (DFH) actuator operable to control a fly height of the head over the disk. A DFH control signal is applied to the DFH actuator to decrease the fly height of the head, wherein the DFH control signal comprises a DC component and an AC component comprising an excitation frequency. A touchdown metric is measured over an interval, and the head contacting the disk is detected in response to a frequency component of the touchdown metric at the excitation frequency.
483 Citations
30 Claims
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1. A disk drive comprising:
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a disk; a head actuated over the disk, the head comprising a dynamic fly height (DFH) actuator operable to control a fly height of the head over the disk; and control circuitry operable to; apply a DFH control signal to the DFH actuator to decrease the fly height of the head, wherein the DFH control signal comprises a DC component and an AC component comprising an excitation frequency; measure a touchdown metric over an interval; and detect the head contacting the disk in response to a frequency component of the touchdown metric at the excitation frequency, wherein the AC component comprises a periodic signal generated at a predetermined frequency high enough to attenuate a response of the DFH actuator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A disk drive comprising:
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a disk; a head actuated over the disk, the head comprising a dynamic fly height (DFH) actuator operable to control a fly height of the head over the disk; and control circuitry operable to; apply a DFH control signal to the DFH actuator to decrease the fly height of the head, wherein the DFH control signal comprises a first periodic signal comprising a first frequency combined with a second periodic signal comprising a second frequency different from the first frequency; measure a touchdown metric over an interval; and detect the head contacting the disk in response to a first frequency component of the touchdown metric at a first excitation frequency and a second frequency component of the touchdown metric at a second excitation frequency. - View Dependent Claims (13)
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14. A method of operating a disk drive comprising a head actuated over a disk, wherein the head comprises a dynamic fly height (DFH) actuator operable to control a fly height of the head over the disk, the method comprising:
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applying a DFH control signal to the DFH actuator to decrease the fly height of the head, wherein the DFH control signal comprises a DC component and an AC component comprising an excitation frequency; measuring a touchdown metric over an interval; and detecting the head contacting the disk in response to a frequency component of the touchdown metric at the excitation frequency, wherein the AC component comprises a periodic signal generated at a predetermined frequency high enough to attenuate a response of the DFH actuator. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A method of operating a disk drive, the disk drive comprising a head actuated over a disk, wherein the head comprises a dynamic fly height (DFH) actuator operable to control a fly height of the head over the disk, the method comprising:
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applying a DFH control signal to the DFH actuator to decrease the fly height of the head, wherein the DFH control signal comprises a first periodic signal comprising a first frequency combined with a second periodic signal comprising a second frequency different from the first frequency; measuring a touchdown metric over an interval; and detecting the head contacting the disk in response to a first frequency component of the touchdown metric at a first excitation frequency and a second frequency component of the touchdown metric at a second excitation frequency. - View Dependent Claims (26)
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27. A disk drive comprising:
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a disk; a head actuated over the disk, the head comprising a dynamic fly height (DFH) actuator operable to control a fly height of the head over the disk; and control circuitry operable to; apply a DFH control signal to the DFH actuator to decrease the fly height of the head, wherein the DFH control signal comprises a DC component and an AC component comprising an excitation frequency; measure a touchdown metric over an interval; and detect the head contacting the disk in response to a frequency component of the touchdown metric at the excitation frequency, wherein the DFH control signal is substantially zero for at least part of the interval while measuring the touchdown metric.
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28. A method of operating a disk drive comprising a head actuated over a disk, wherein the head comprises a dynamic fly height (DFH) actuator operable to control a fly height of the head over the disk, the method comprising:
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applying a DFH control signal to the DFH actuator to decrease the fly height of the head, wherein the DFH control signal comprises a DC component and an AC component comprising an excitation frequency; measuring a touchdown metric over an interval; and detecting the head contacting the disk in response to a frequency component of the touchdown metric at the excitation frequency, wherein the DFH control signal is substantially zero for at least part of the interval while measuring the touchdown metric.
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29. A disk drive comprising:
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a disk; a head actuated over the disk, the head comprising a dynamic fly height (DFH) actuator operable to control a fly height of the head over the disk; and control circuitry operable to; apply a DFH control signal to the DFH actuator to decrease the fly height of the head, wherein the DFH control signal comprises a DC component and an AC component comprising an excitation frequency; measure a touchdown metric over an interval; and detect the head contacting the disk in response to a frequency component of the touchdown metric at the excitation frequency, wherein the touchdown metric comprises a vector Z comprising a magnitude and a phase, wherein the phase of the vector Z is relative to a phase of the DFH control signal.
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30. A method of operating a disk drive comprising a head actuated over a disk, wherein the head comprises a dynamic fly height (DFH) actuator operable to control a fly height of the head over the disk, the method comprising:
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applying a DFH control signal to the DFH actuator to decrease the fly height of the head, wherein the DFH control signal comprises a DC component and an AC component comprising an excitation frequency; measuring a touchdown metric over an interval; and detecting the head contacting the disk in response to a frequency component of the touchdown metric at the excitation frequency, wherein the touchdown metric comprises a vector Z comprising a magnitude and a phase, wherein the phase of the vector Z is relative to a phase of the DFH signal.
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Specification