Capacitive height sensing electronics for hard disk drive application
AssigneeAvago Technologies International Sales Pte. Limited
InventorScott O'Brien
Life of this patent
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Abstract
An assembly including a capacitive height sensor and a conditioning circuit. The capacitive height sensor detects capacitance between a read/write head and a disk surface to monitor variances in a flying height. To bring about a measurement voltage between the capacitive height sensor and the disk surface, the conditioning circuit supplies a drive current to the capacitive height sensor. The conditioning circuit ceases flowing the drive current to the capacitive height sensor upon detecting that the measurement voltage is greater than a high threshold, and commences flowing the drive current to the capacitive height sensor upon detecting that the measurement voltage is less than a low threshold.
Claims18
An apparatus comprising:
- a current source configured to:
- transform a positive voltage into a drive current, and
- provide, to bring about a measurement voltage between a sensor and a target object, the drive current to the sensor, wherein the current source comprises a plurality of slices, each slice is configured to individually flow a predetermined amount of the drive current;
- and
- an oscillator configured to:
- prevent, in response to detecting that the measurement voltage is greater than a first threshold, the current source from flowing the drive current, and
- enable, in response to detecting that the measurement voltage is less than a second threshold, the current source to commence flowing the drive current,
- wherein the first threshold is a voltage level higher than the second threshold;
- and
- wherein a frequency of the measurement voltage is proportional to the amplitude of the drive current.
A method comprising:
- detecting, by a capacitive height sensor to monitor variances in a flying height, capacitance between a read/write head and a disk surface;
- provided, by a conditioning circuit to generate a voltage between the capacitive height sensor and a target object, a drive current to the capacitive height sensor;
- cease, by the conditioning circuit in response to detecting that the voltage is greater than a first threshold, flowing the drive current to the capacitive height sensor;
- and
- commence, by the conditioning circuit in response to detecting that the voltage is less than a second threshold, flowing the drive current to the capacitive height sensor,
- wherein the first threshold is a voltage level higher than the second threshold;
- and
- wherein a frequency of the voltage is proportional to the amplitude of the drive current.
An assembly comprising:
- a capacitive height sensor configured to:
- detect, to monitor variances in a flying height, capacitance between a read/write head and a disk surface;
- and
- a conditioning circuit configured to:
- provide, to bring about a voltage between the capacitive height sensor and the disk surface, a drive current to the capacitive height sensor,
- cease, in response to detecting that the voltage is greater than a first threshold, providing the drive current to the capacitive height sensor, and
- commence, in response to detecting that the voltage is less than a second threshold, providing the drive current to the capacitive height sensor,
- wherein the first threshold is a voltage level higher than the second threshold;
- and
- wherein a frequency of the voltage is proportional to the amplitude of the drive current.
Dependencies are inferred from the claim text.