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    11.
    发明专利
    未知

    公开(公告)号：DE69120600D1

    公开(公告)日：1996-08-08

    申请号：DE69120600

    申请日：1991-04-26

    Applicant: IBM

    Inventor： KLAASSEN KLAAS BEREND ,  VAN PEPPEN JACOBUS CORNELIS LE

    IPC: G11B5/09 ,  G11B5/465 ,  G11B5/55 ,  G11B19/04 ,  G11B5/03

    Abstract: A magnetic recording system includes a current- tapering circuit which gradually reduces the WRITE current in a magnetic recording head to zero over a time interval on the same order of magnitude as the characteristic relaxation time of the domain patterns in the magnetic recording head, rather than abruptly. Specific embodiments of the current-tapering circuit create a down-sloping ramp, a decaying exponential curve, and a high-frequency burst. The resultant magnetic recording system has reduced Barkhausen noise and reproducible READ performance as well as improved READ sensitivity following a WRITE operation.

    13.
    发明专利
    未知

    公开(公告)号：DE69103321T2

    公开(公告)日：1995-03-23

    申请号：DE69103321

    申请日：1991-05-01

    Applicant: IBM

    Inventor： JOVE STEPHEN ALAN ,  KLAASSEN KLAAS BEREND ,  NOMURA CALVIN SHIZUO ,  VAN PEPPEN JACOBUS CORNELIUS L

    IPC: G11B5/02 ,  G01R33/09 ,  G11B5/00 ,  G11B5/39 ,  G11B5/40 ,  G01R33/06

    Abstract: An amplifier circuit produces an electrical output signal whose magnitude is representative of a signal produced by a magnetoresistive (MR) element (Rmr) and also protects the MR element (Rmr) from electrical short circuits between the element (Rmr) and on adjacent conductive surface. A first feedback loop biases the MR element (Rmr) with a bias current and amplifies a signal current for causing the MR element (Rmr) to produce a circuit output signal corresponding to dRh/Rh and in which any dc offset error is minimized R h is the resistance of the MR element and dRh is the magnetic-signal-induced change in the resistance of the MR element. A second feedback loop insures that the MR element (Rmr) is held at a preselected reference potential and that no current will flow sufficiently to damage the element in the event of a short circuit between the element and the surface. The feedback loops are interconnected by outputs of the respective feedback loops being commonly connected to the bases of a pair of input bipolar transistors (Q1,Q2), whose respective emitters are connected to opposite terminals of the MR element (Rmr).

    14.
    发明专利
    未知

    公开(公告)号：DE3787428D1

    公开(公告)日：1993-10-21

    申请号：DE3787428

    申请日：1987-07-24

    Applicant: IBM

    Inventor： BROWN BYRON RICHARD ,  HU HUNG LIANG ,  KLAASSEN KLAAS BEREND ,  LUM JOSEPH JACK ,  VAN PEPPEN JACOBUS CORNELIS LE ,  WERESIN WALTER EUGENE

    IPC: G01B7/00 ,  G11B5/00 ,  G11B5/012 ,  G11B5/60 ,  G11B21/21 ,  G11B27/36 ,  G11B5/48 ,  G11B5/455

    Abstract: In a method of measuring the flying height of a slider supporting a magnetic transducer in an operational magnetic storage system, relative motion is produced between the magnetic transducer and a magnetic recording medium at a first velocity so that the resulting air bearing positions the magnetic transducer slider at a first flying height from the magnetic medium. A single signal of constant periodicity is written over a predetermined area of the recording medium by the magnetic transducer, and a readback signal is sensed from the predetermined area of the recording medium to produce a first signal. The flying height of the magnetic transducer slider is lowered to substantially zero, and a readback signal is sensed at the lowered flying height to produce a second signal. The first flying height is then calculated as the ratio, expressed in decibels, of the first and second signals times the wavelength divided by a constant. In another embodiment a plurality of signals are recorded and readback signals are simultaneously sensed at two separate wavelengths. In a further embodiment, a signal is recorded which has a spectral content comprising a plurality of different frequencies, and readback signals are simultaneously sensed at two separate wavelengths.

    SIGNAL SEPARATION IN MAGNETIC RECORDING SYSTEMS USING BURIED SERVO RECORDS
    17.
    发明专利
    SIGNAL SEPARATION IN MAGNETIC RECORDING SYSTEMS USING BURIED SERVO RECORDS 未知

    公开(公告)号：DE3174094D1

    公开(公告)日：1986-04-17

    申请号：DE3174094

    申请日：1981-12-02

    Applicant: IBM

    Inventor： KLAASSEN KLAAS BEREND

    IPC: G05D3/12 ,  G11B5/58 ,  G11B5/596 ,  G11B21/10 ,  H03K5/02 ,  G11B5/02

    Abstract: To prevent the voltage generated in the transducer while writing data from masking out the servo information in a magnetic recording system using a recording medium having a pre-recorded, buried servo record and the same transducer (Zh) for simultaneously reading the servo record and writing data above the servo record, the system includes a dummy impedance (Zh min ) through which a compensating current is driven to produce a voltage which opposes the voltage generated in the transducer by the data-writing current. An alternative to the bridge circuit, employs separate drivers, driven in opposite phase, for the transducer and the dummy impedance. Transformers can be used instead of resistors as the loads of the driver transistors.

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