Seagate Technology Incorporated

Ghassan M Abdelnour

Housan Dakroub

Jeffrey A Heydt

Roger J Kassab

Alfredo Gay Sam

Horace David Chandler

Steven Hill Rogers

A method for determining whether a data storage device read/write head is a low-flying read/write head or a non low-flying read/write head. A disc attached to a spindle motor is accelerated to an operating rotational velocity, the head is positioned over a portion of the disc non-accessible to customer data and a data pattern of selected frequency is written. A magnetoresistive element of the is biased and the data pattern is read while the disc is decelerated to a predetermined rotational velocity threshold. Occurrence of a read signal landing signature comprising readback signal amplitude modulation prior to reaching the predetermined rotational velocity threshold identifies the head as a low-flying head. Contrawise, non-occurrence of the read signal landing signature prior to reaching the predetermined rotational velocity threshold signifies the head as a non low-flying head.

Low flying head detection using readback signal amplitude modulation

A method for improving read error rates in a disc drive employing repeatable run-out compensation for writing but not for reading is disclosed. Pursuant to the method, a repeatable run-out compensation system which compensates for repeatable run-out during write operations but not during read operations is implemented. After implementing the repeatable run-out compensation system, reader-to-writer offset calibration is performed. In one embodiment of the present invention, after implementing the repeatable run-out compensation system, read error rates are experimentally determined for a given data track across a range of reader-to-writer offset values. Then a curve representing read error rates as a function of reader-to-writer offset is generated. The optimum reader-to-writer offset is then determined based on the shape of the curve. A disc drive employing this method is also disclosed.

Calibration of reader/writer offset in a disc drive

A method for optimizing data transfer performance in a disc drive through selection of optimal reader/writer offsets and write fault thresholds. An initial offset for a selected track is determined as the radial distance between read and write elements of a head as the head is positioned adjacent a selected track. Asymmetric write fault thresholds are selected on opposing sides of the center of the selected track in relation to the ability of the read element to successfully recover data written to the track. An adjustment value is determined in relation to the asymmetry of the write fault thresholds, and the adjustment value is used to modify the initial offset to form a final offset, as well as to make the write fault thresholds symmetric about the center of the track.

Optimal reader/writer offsets and write fault thresholds in a disc drive

Method for optimizing parameter values in a read/write channel of a disc drive. A population of error rate points is obtained from selected ranges of a plurality of read/write channel parameters, each error rate point corresponding to a unique combination of parameter values and having an associated error rate value. A weight is determined for each of the error rate points through normalization to the minimum error rate value in the population. A threshold value is determined based upon the error rate values in a plurality of nominally identical disc drives and the weights are compared to the threshold value. Those error rate values having weights less than the threshold are selected and a center of gravity is determined therefrom. At such times that the entire population of error rate values has weights greater than the threshold value, the optimum parameter values are those that map to the center of gravity. Otherwise, for each error rate value having a weight greater than the threshold, the average and standard deviation are determined for neighboring (immediately adjacent) error rate values and the error rate value having the tightest distribution in the neighboring error rate values provides the optimum parameter values.

Selection of optimal read/write channel parameters in a hard disc drive

Apparatus and method for the early detection of faults in a head-disc assembly (HDA) from a disc drive manufacturing process. Parametrics are obtained from an HDA at a parametric station and provided to a pattern recognition system for estimating an error rate category from the measured HDA parametrics. The estimated error rate category and the parametrics are provided to a fuzzy inferencing system, which uses linguistic rules to classify the HDA as GOOD, MARGINAL or BAD, based upon the parametrics and the estimated error rate category. HDAs classified as GOOD or MARGINAL continue processing through dynamic burn-in (DBI), while HDAs classified as BAD are subjected to rework. The pattern recognition system includes a reference database containing historical parametric and associated error rate data, which is updated over time by the subsequent inclusion of selected parametrics and measured error rates for HDAs subjected to DBI.

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Oklahoma City, OK, United States of America

Ghassan M Abdelnour