公开(公告)号：DE69108270T2

公开(公告)日：1995-10-19

申请号：DE69108270

申请日：1991-01-18

Applicant: IBM

Inventor： CHUNG PAUL WINGSHING ,  JENKINS MICHAEL OWEN ,  JOVE STEPHEN ALAN ,  KLAASSEN KLAAS BEREND ,  SABER PAIK ,  VAN PEPPEN JACOBUS CORNELIUS L

IPC: G11B5/09 ,  G11B5/00 ,  G11B5/012 ,  G11B5/02 ,  G11B20/02 ,  G11B20/24 ,  G11B20/00 ,  H03H21/00

公开(公告)号：HK139294A

公开(公告)日：1994-12-16

申请号：HK139294

申请日：1994-12-08

Applicant: IBM

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

IPC: G11B5/39 ,  G11B5/00 ,  G11B5/02 ,  G11B5/40 ,  G11B19/04 ,  H03F3/72

Abstract: The invention relates to a protection circuit for a magnetoresistive (MR) element (Rh) having a first terminal and a second terminal in which a first current source is coupled to the first terminal of the MR element to produce a bias current (J1) through the MR element and a second current source is coupled to the second terminal of the MR element to produce a reference current (Iref). According to the invention, circuit means (R,R,B) coupled across the MR element (Rh) senses the centre potential of the MR element substantially midway between the first and second terminals, and a feedback circuit (B) responsive to the sensed centre potential adjusts the current output of the first current source (J1) to maintain the centre potential to a selected reference voltage (Vcentre) to protect the MR element (Rh) from short circuits to a conductive area of the magnetisable recording medium being read by the MR element.

公开(公告)号：DE69103321D1

公开(公告)日：1994-09-15

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).

公开(公告)号：DE3787428T2

公开(公告)日：1994-04-21

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.

公开(公告)号：DE3778291D1

公开(公告)日：1992-05-21

申请号：DE3778291

申请日：1987-10-13

Applicant: IBM

Inventor： JOVE STEPHEN ALAN ,  KLAASSEN KLAAS BEREND ,  VANPEPPEN JACOBUS CORNELIS LEO ,  VO CHON NGOC

IPC: H03F1/34 ,  G11B5/02 ,  G11B5/035 ,  H03F1/08 ,  H03F1/48 ,  H03G7/00