Dynamic magnetic information storage or retrieval – General processing of a digital signal – Pulse crowding correction
Patent
1993-06-08
1995-02-21
Hajec, Donald
Dynamic magnetic information storage or retrieval
General processing of a digital signal
Pulse crowding correction
361149, 365 38, G11B 509, H01F 1300, H01H 4700, G11C 1908
Patent
active
053921690
ABSTRACT:
A method and apparatus for conditioning a magnetic read/write head to substantially eliminate read-back pulse distortions associated with unfavorable magnetic domain patterns in the head stores the polarity of the last write current pulse of a write pulse train applied to the head-coils. This polarity is compared to a pre-determined reset current pulse polarity. If the last write current polarity is opposite to the reset current polarity, then a reset pulse, or a series of pulses, having the pre-determined reset polarity is applied to the head prior to performing a read operation with the head. The pre-determined reset polarity corresponds to the polarity that resets the head to the magnetic domain state most preferred for reading due to reduction of read-back distortion. The reset pulse, or pulse train, according to the present invention is of constant polarity. If the last write current pulse polarity is the same as the reset polarity, then no reset pulse is applied to the head. Prior to applying the reset pulse, the head is either re-positioned or, if not re-positioned, the reset pulse is applied to the head only when it is flying over a sector gap.
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Argyle Bernell E.
Praino Anthony P.
Re Mark E.
Schafer Rudolf
Takayama Shinji
Hajec Donald
International Business Machines - Corporation
Wamsley Patrick
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