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    14.
    发明专利
    未知

    公开(公告)号：DE69221049T2

    公开(公告)日：1998-01-15

    申请号：DE69221049

    申请日：1992-09-04

    Applicant: IBM

    Inventor： CALL DAVID ERNEST ,  LEWKOWICZ JULIAN

    IPC: G11B7/00 ,  G11B7/0045 ,  G11B7/0055 ,  G11B7/125 ,  G11B7/09 ,  H01S3/00

    Abstract: Method and apparatus for calibrating the drive current circuit of a semiconductor laser diode subject to reflected optical feedback from a target surface such an an optical recording disk. The method makes use of two power output vs. drive current characteristic curves for the laser, one curve 190 for in-focus condition and the other curve 191 for out-of-focus condition, wherein the curves exhibit an asymptotic region at high power level (P2). Measurement of drive current I2 at power level P2 is taken under an out-of-focus condition. Measurement of drive current I1 and I3 at a predetermined low power level P1 are taken for both out-of-focus condition and in-focus condition. The linear slope of the in-focus curve 190 can thus be calculated to set desired power levels.

    15.
    发明专利
    未知

    公开(公告)号：DE69016246T2

    公开(公告)日：1995-06-29

    申请号：DE69016246

    申请日：1990-04-04

    Applicant: IBM

    Inventor： BLETSHER WARREN LEROY ,  TAYEFEH MOROVAT ,  LEWKOWICZ JULIAN

    IPC: G11B11/10 ,  G11B7/00 ,  G11B7/0045 ,  G11B7/125 ,  G11B11/105 ,  G11B27/36 ,  G11B7/12

    Abstract: Recording operations for an optical disk recorder are calibrated by adjusting recording power level (light intensity) such that a permissible crosstalk can be detected in adjacent erased tracks. Following the power level calibration, pulse duration or width is calibrated for a predetermined symmetry of recorded pulses along the calibration track. Various sequences and procedures are described. Calibration occurs at a plurality of radially spaced-apart tracks.

    17.
    发明专利
    未知

    公开(公告)号：DE3681974D1

    公开(公告)日：1991-11-21

    申请号：DE3681974

    申请日：1986-06-25

    Applicant: IBM

    Inventor： LEWKOWICZ JULIAN

    IPC: G11B11/00 ,  G11B7/00 ,  G11B7/0045 ,  G11B7/125 ,  G11B11/105 ,  G11B7/013 ,  G11B11/10 ,  G11B13/04

    Abstract: An optical information-bearing-signal recorder employs thermally-induced recording of ablative, material movement, material phase change, magneto-optic or similar technologies. Synchronous noise in the recording is reduced by employing a heat-inducing energy pulse (25), coherent light for example, shaped to have an initial recording-initiating intensity amplitude (44, 44A) followed by a recording-sustaining amplitude (55, 55A). The duration of the recording-initiating amplitude portion is constant for all lengths of signals being recorded. When a rotating optical disk is employed as a record-bearing medium, the recording-initiating and recording-sustaining amplitudes are increased with increasing radius of the recording on the disk.

    BIASING OF MAGNETORESISTIVE READ HEAD USING GYRATORS
    18.
    发明专利
    BIASING OF MAGNETORESISTIVE READ HEAD USING GYRATORS 未知

    公开(公告)号：CA1127299A

    公开(公告)日：1982-07-06

    申请号：CA332289

    申请日：1979-07-20

    Applicant: IBM

    Inventor： LEWKOWICZ JULIAN

    IPC: G11B5/09 ,  G11B5/02 ,  G11B5/027 ,  G11B5/03 ,  G11B5/39 ,  H03H11/42

    Abstract: BIASING OF MAGNETORESISTIVE READ HEAD USING GYRATORS An electromagnetic transducer particularly of the magneto-resistive (MR) type is biased by an inductive circuit means and operates within the linear portion of its characteristic curve. The inductive circuit means is interconnected to the output terminals of said transducer. An amplifier means is connected to the output terminals of the transducer and the inductive circuit means. The amplifier means is also biased by the inductive circuit means. The biasing scheme is enhanced when a gyrator is used as the inductive circuit means. BO978008

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