Suppression of magnetic instability in inductive recording heads
AssigneeInternational Business Machines Corporation
InventorsKlaas B. Klaasen, Jacobus C. L. van Peppen
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Abstract
Circuitry for eliminating magnetic instability of an inductive magnetic transducer during sensing of data from a magnetic recording medium to prevent distortion of the readback signal by hysterically moving domain walls. An inductive sensing coil has an impedance constituting the output impedance of the transducer. Means connected to the coil amplifies a data signal generated by the magnetic flux changes and produces a selected input impedance. The sum of these input and output impedances is selected to be small enough to substantially eliminate motion of the domain walls in the yoke of the transducer while the transducer is sensing data from the medium.
Claims13
For use with a magnetic recording medium, circuitry comprising:
- an inductive magnetic transducer (10) having (i) a yoke region (12) with magnetic domain walls separating differently oriented magnetic domains and (ii) and inductive sensing coil (14) for sensing data on the recording medium and generating a data signal produced by magnetic flux changes, said coil having an impedance constituting the output impedance (Z.sub.h) of the transducer;
- and
- means (22) connected to the coil for amplifying the data signal and having as an input an electronics input impedance (Z.sub.in), where Z.sub.in =-Z.sub.h (1-.epsilon.) and .epsilon. has a value between +1 and -1, the vectorial sum of said input and output impedances having a magnitude that (i) inhibits motion of the domain walls in the yoke region, while the transducer is sensing data, and (ii) inhibits flux variations of the data signal at frequencies at which motion of the domain walls can occur.
A method of inhibiting motion of the magnetic domain walls of the yoke region of an inductive magnetic transducer that includes an inductive sensing coil that senses data on a magnetic recording medium, generates a data signal from magnetic flux changes, and has an impedance constituting the output impedance (Z.sub.h) of the transducer, comprising the steps of:
- amplifying the data signal with a circuit including an amplifier connected to the coil and having as an input a selectable electronics input impedance (Z.sub.in);
- and
- selecting input and output impedances such that Z.sub.in =-Z.sub.h (1-.epsilon.), where .epsilon. has a value between +1 and -1 and the vectorial sum of said impedances has a magnitude that (i) inhibits said motion of the domain walls in the yoke region, while the transducer is sensing data, and (ii) inhibits flux variations of the data signal at frequencies at which motion of the domain walls can occur.
Dependencies are inferred from the claim text.