Clearance distance verification and control
AssigneeSeagate Technology LLC
InventorsRichard E. Martin, Quinn J. Haddock
Life of this patent
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Abstract
Method and apparatus for verifying and controlling a clearance distance of an object, such as but not limited to a fly height of a read/write transducer adjacent a recording medium in a data storage device. In accordance with some embodiments, a sensor is used to sense a plurality of patterns from an adjacent surface, with each pattern being written at a different constant frequency. A final clearance distance between the sensor and the surface is established in response to a multi-frequency response ratio from the sensor and a single frequency response ratio from the sensor.
Claims20
A method comprising:
- using a sensor to sense a plurality of patterns from an adjacent surface, each pattern written at a different constant frequency;
- and
- setting a final clearance distance between the sensor and the surface in response to a multi-frequency response ratio from the sensor at the final clearance distance and a single frequency response ratio from the sensor at the final clearance distance.
An apparatus comprising:
- a sensor positioned adjacent a surface with a plurality of oscillating patterns at different constant frequencies written thereto;
- a clearance adjustment mechanism configured to change a clearance distance between the sensor and the surface;
- and
- a processing circuit adapted to control a clearance distance between the sensor and the surface by performing a first regression of a plurality of multi-harmonic ratio values obtained as the sensor senses the plurality of oscillating patterns, performing a second regression of a plurality of single harmonic ratio values obtained as the sensor senses one of the plurality of oscillating patterns, and comparing a slope of the second regression to a slope of the first regression at a target clearance distance.
An apparatus comprising:
- a data recording medium;
- a read/write transducer adjacent the data recording medium and comprising a data read sensor, a data writer and a heater;
- and
- a processing circuit configured to direct the data writer to write a plurality of patterns to the medium with each pattern having a different constant frequency, to direct the read sensor to sense the plurality of patterns, to generate a multi-frequency response ratio value, a single frequency response ratio value from the sensed patterns and a single sided confidence interval at a selected confidence level with the transducer at a target clearance distance from the medium, and to output a power input value to the heater to adjust a clearance distance between the transducer and the medium responsive to the multi-frequency and single frequency response ratio values and responsive to the single sided confidence interval being less than the target clearance distance.
Dependencies are inferred from the claim text.