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公开(公告)号：JP2002197602A
公开(公告)日：2002-07-12
申请号：JP2001332187
申请日：2001-10-30
Applicant: IBM
Inventor： BHAUMIK JAYDIP , KERTIS ROBERT ANDREW , KLAASSEN KLAAS BEREND , RAYMOND ALLAN RICHIETTA , VAN PEPPEN JACOBUS CORNELIS LE
Abstract: PROBLEM TO BE SOLVED: To provide a correction device for the magneto-resistance asymmetry and its method so that an asymmetric pulse from a magneto-resistance head is easily and efficiently corrected. SOLUTION: The device is provided with a shift circuit, 1st gain circuit, 2nd gain circuit and 3rd gain circuit. In the shift circuit, a shifted recording signal is produced by adding or dividing the shifted value with respect to a reading signal in accordance with the polarity of asymmetry. The reading signal, the shifted reading signal and the shifted value are produced by the shift circuit. The reading signal, the shifted reading signal and the shifted value are respectively received by the 1st, 2nd and 3rd gain circuits, and outputs amplified in accordance with each control signal are respectively produced. The reading signal is received by a control means to detect the polarity of the optional asymmetry of the reading signal, then a polarity signal is given to the shift circuit in accordance with the required correction amount, and also the respective control signals are given to the 1st, 2nd and 3rd gain circuits.
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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
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.
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公开(公告)号：DE69317185T2
公开(公告)日：1998-10-29
申请号：DE69317185
申请日：1993-09-16
Applicant: IBM
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公开(公告)号：DE69317084D1
公开(公告)日：1998-04-02
申请号：DE69317084
申请日：1993-07-14
Applicant: IBM
IPC: G11B5/00 , G11B5/012 , G11B5/02 , G11B5/11 , G11B5/39 , G11B5/40 , G11B5/55 , G11B19/02 , G11B19/04 , G11B23/50 , G11B33/00 , G11B33/14 , H03F3/04 , H03F3/195 , G11B20/24 , G01R33/06
Abstract: Low noise, low power, low voltage amplifier circuits with a single ended input having no common mode rejection for concurrently biasing and amplifying signals generated by magnetoresistive (MR) elements in a disk file. The amplifier circuits comprise a single (grounded) supply voltage source. One terminal of each MR element and the conductive substrate of each MR element and the conductive substrate of each disk in the disk file are grounded to minimize transient conductive asperity currents. The head/disk assembly of the disk file is completely enclosed by a highly conductive electrostatically shielded metallic enclosure that.. operates as a Faraday cage and isolates leads connecting the MR elements with the amplifier circuit from large, fast rise/fall time voltage transients.
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Patent Agency Ranking
公开(公告)号：DE69120600T2
公开(公告)日：1997-01-23
申请号：DE69120600
申请日：1991-04-26
Applicant: IBM
Inventor： KLAASSEN KLAAS BEREND , VAN PEPPEN JACOBUS CORNELIS LE
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.
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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
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.
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公开(公告)号：DE68914744T2
公开(公告)日：1994-11-24
申请号：DE68914744
申请日：1989-06-23
Applicant: IBM
IPC: G11B5/09 , G11B5/00 , G11B5/012 , G11B5/02 , G11B5/40 , G11B19/04 , G11B20/00 , G11B20/22 , G11B33/10
Abstract: A method and circuitry are disclosed for suppressing additive transient disturbances in a data channel; e.g., due to thermal transients caused by an MR transducer contacting a moving storage surface. Positive and negative envelope detectors (11, 12) each have their inputs connected to the channel, and provide respective outputs which are summed (13) and contain an envelope component and a residue component. A buffer (14) interconnects the detectors to allow both detectors (11, 12) to follow rapid positive excursions of the data channel signal. A nonlinear signal-adaptive filter (15) is connected to the summed output to further reduce the residue component. The data channel signal (or preferably the output from a delay means connected to the channel) is summed with the output from the filter. The relative amplitudes of these two outputs is set such that the resulting summed output signal is free of additive disturbances.
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公开(公告)号：DE68914744D1
公开(公告)日：1994-05-26
申请号：DE68914744
申请日：1989-06-23
Applicant: IBM
IPC: G11B5/09 , G11B5/00 , G11B5/012 , G11B5/02 , G11B5/40 , G11B19/04 , G11B20/00 , G11B20/22 , G11B33/10
Abstract: A method and circuitry are disclosed for suppressing additive transient disturbances in a data channel; e.g., due to thermal transients caused by an MR transducer contacting a moving storage surface. Positive and negative envelope detectors (11, 12) each have their inputs connected to the channel, and provide respective outputs which are summed (13) and contain an envelope component and a residue component. A buffer (14) interconnects the detectors to allow both detectors (11, 12) to follow rapid positive excursions of the data channel signal. A nonlinear signal-adaptive filter (15) is connected to the summed output to further reduce the residue component. The data channel signal (or preferably the output from a delay means connected to the channel) is summed with the output from the filter. The relative amplitudes of these two outputs is set such that the resulting summed output signal is free of additive disturbances.
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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
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.
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