Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the head
Patent
1997-07-11
1999-08-31
Edun, Muhammad
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the head
360 75, G11B 5596
Patent
active
059461586
ABSTRACT:
The invention is a method of calibrating a position error signal (PES) to overcome the problem of a measured displacement or PES that varies as a non-linear function of real displacement when the read transducer is positioned to either side of a null position where the PES equals zero. The PES is notably nonlinear while reading servo burst information with a Magneto-Resistive (MR) head which has nonlinear magnetic characteristics. The method uniquely calibrates the measured PES to provide a corrected PES without requiring any knowledge of the actual displacement from the position where the measured PES equals 0. The calibration according to this method, therefore, may be performed at anytime without need for real displacement information from a servowriter or any sort of special calibration track. The method involves positioning the MR head to a plurality of predetermined, measured displacements corresponding to partial track increments of real displacement of unknown magnitude on either side of the null position, measuring a PES gain value at each of the plurality of measured displacements, and then correcting subsequent measured displacements based on the plurality of measured displacements and corresponding PES gain values. The correcting step is preferably accomplished by using the measured displacements and corresponding PES gain values to establish coefficients of a correction function c(y) which substantially provides unity gain relative to real displacement over a limited range of measured displacements. The preferred correction function c(y) is a partial sum Fourier series.
REFERENCES:
patent: 5457586 (1995-10-01), Solhjell
patent: 5844675 (1998-12-01), Hayes et al.
Nazarian Ara W.
Trieu Thao P.
Wong Richard K.
Edun Muhammad
Shara Milad
Western Digital Corporation
Young Leo J.
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