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    1.
    发明专利
    未知

    公开(公告)号：DE3750315D1

    公开(公告)日：1994-09-08

    申请号：DE3750315

    申请日：1987-05-19

    Applicant: IBM

    Inventor： CHRISTENSEN THOMAS CHARLES ,  JAWORSKI RICHARD CASIMIR ,  COKER JONATHAN DARREL ,  KERWIN GREGORY JOHN ,  CUNNINGHAM EARL ALBERT ,  PALMER DEAN CURTIS ,  ROEPKE JEFFREY RALPH

    IPC: G11B5/09 ,  G11B5/00 ,  G11B5/012 ,  G11B5/035 ,  G11B5/455 ,  G11B20/18 ,  G11B27/36

    Abstract: A magnetic disk drive channel circuitry is shown and described that generates eight incremental values of write current and eight incremental values of delta-V (the minimum voltage change per unit time which tests signals to discriminate between data and noise). Each of these variable parameter values may be program selected by a three bit bus signal. This variability testing of and adaptation to the optimum parameter value for each head media combination and by grouping tracks in contiguous data bands, the parameters may be optimized for tracks near the inner diameter, the outer diameter and in the middle band. The variable delta-V can also be used as an additional data recovery tool wherein re-reading with a lower value enhances recovery of missing bit errors and re-reading with an increased value can assist recovery from an extra bit error.

    Read error compensated in data storage systems
    2.
    发明专利
    Read error compensated in data storage systems 未知

    公开(公告)号：SG42810A1

    公开(公告)日：1997-10-17

    申请号：SG1995002122

    申请日：1992-06-23

    Applicant: IBM

    Inventor： CHRISTENSEN THOMAS CHARLES ,  ROOKE MATTHEW WILLIAM ,  WORKMAN MICHAEL LEE

    IPC: G11B21/10 ,  G11B5/55 ,  G11B7/13 ,  G11B20/10 ,  G11B20/18 ,  G06F12/00 ,  G11B5/596 ,  G11B21/18

    Abstract: A data storage system using a moving storage medium quickly measures and accurately compensates for thermal and mechanical errors in the position of the data detector with respect to the written data. This is accomplished by measuring the error rate of the written data as a function of the read offset of the detector. Error rates become increasingly large as the sensed noise to signal ratio becomes large. The number of errors detected in reading written data for various read offsets when the data storage system is initially activated is counted. When the number of errors reaches a target rate, the read offset required to produce the target rate is saved. This procedure is performed on either side of the data track. The detector is then centered between the two offsets. During the operation of the storage system, thermal and mechanical errors are introduced into the detector position compensation means. The present invention compensates for this by periodically determining a new offset for each side of the data track. The new offset which corresponds to the target error rate is found by interpolating between measured offsets for error rates which are higher and lower respectively than the target error rate. The new measured read offsets are obtained by reading back written data in a similar manner as was used to obtain the initial read offsets. The detector is then recentered with respect to the write transducer position between the new offsets on either side of the data track.

    8.
    发明专利
    未知

    公开(公告)号：DE3750315T2

    公开(公告)日：1995-03-09

    申请号：DE3750315

    申请日：1987-05-19

    Applicant: IBM

    Inventor： CHRISTENSEN THOMAS CHARLES ,  JAWORSKI RICHARD CASIMIR ,  COKER JONATHAN DARREL ,  KERWIN GREGORY JOHN ,  CUNNINGHAM EARL ALBERT ,  PALMER DEAN CURTIS ,  ROEPKE JEFFREY RALPH

    IPC: G11B5/09 ,  G11B5/00 ,  G11B5/012 ,  G11B5/035 ,  G11B5/455 ,  G11B20/18 ,  G11B27/36

    Abstract: A magnetic disk drive channel circuitry is shown and described that generates eight incremental values of write current and eight incremental values of delta-V (the minimum voltage change per unit time which tests signals to discriminate between data and noise). Each of these variable parameter values may be program selected by a three bit bus signal. This variability testing of and adaptation to the optimum parameter value for each head media combination and by grouping tracks in contiguous data bands, the parameters may be optimized for tracks near the inner diameter, the outer diameter and in the middle band. The variable delta-V can also be used as an additional data recovery tool wherein re-reading with a lower value enhances recovery of missing bit errors and re-reading with an increased value can assist recovery from an extra bit error.

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