Smear height detection and measurement in a data storage device
AssigneeWestern Digital Technologies, Inc.
InventorsBernhard E. Knigge, Yuichi Aoki, Yukio Kato, Wangzhen Zhao
Life of this patent
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Abstract
A data storage device comprises a disk and a recording head. A thermal fly-height control (TFC) heater thermally adjusts a spacing of the recording head from a surface of the disk. A thermal proximity sensor detects a spacing of the recording head from the disk surface and generates a thermal proximity sensor signal indicative of the detected spacing. A height of smear accumulated on the recording head is determined by dithering the TFC heater about a DC power level, measuring a skewness in the thermal proximity sensor signal while the TFC heater is being dithered, and determining the smear height from the measured skewness.
Claims20
A data storage device comprising:
- a disk;
- a recording head;
- a thermal fly-height control (TFC) heater configured to thermally adjust a spacing of the recording head from a surface of the disk;
- a thermal proximity sensor configured to detect a spacing of the recording head from the disk surface and to generate a thermal proximity sensor signal indicative of the detected spacing;
- and
- one or more processing devices, individually or in combination, configured to:
- dither the TFC heater about a direct current (DC) power level;
- measure a skewness in the thermal proximity sensor signal while the TFC heater is being dithered;
- and
- determine, from the measured skewness, a height of smear accumulated on the recording head.
A method for detecting smear height on a recording head of a data storage device, the method comprising:
- dithering a thermal fly-height control (TFC) heater that is configured to thermally adjust a spacing of the recording head from a surface of a disk of the data storage device about a direct current (DC) power level;
- measuring a skewness in a thermal proximity sensor signal indicative of the spacing of the recording head from the disk surface while the TFC heater is being dithered;
- and
- determining, from the measured skewness, a height of smear accumulated on the recording head.
A data storage device comprising:
- a disk;
- a recording head;
- a thermal fly-height control (TFC) heater configured to thermally adjust a spacing of the recording head from a surface of the disk;
- a thermal proximity sensor configured to detect a spacing of the recording head from the disk surface and to generate a thermal proximity sensor signal indicative of the detected spacing;
- and
- one or more processing device means, individually or in combination, configured to:
- gradually increase a power of the TFC heater;
- monitor the thermal proximity sensor signal as the TFC heater power is increased;
- and
- detect a cooling signature in the thermal proximity sensor signal that is indicative of accumulation of smear on the recording head.
Dependencies are inferred from the claim text.