US 4,399,422 AGranted

Magnetizing apparatus

AssigneeWang Laboratories, Inc.

InventorsAlfred M. Nelson, Houshang Rasekhi, John J. Sudano

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Abstract

Apparatus is provided for uniformly premagnetizing magnetic media, such as wide magnetic tapes and/or for substantially uniformly orienting the magnetic particles in the slurry of the magnetizable layer of magnetic media during their formation. Premagnetization constitutes magnetizing the medium in a preselected direction, such as the transverse direction (i.e., perpendicular to the intended direction of movement of the recording medium past a recording head but in the plane of the medium), prior to magnetically recording information thereon. The apparatus comprises a number of predeterminably arranged small magnets disposed proximate to the medium which obviates the need for large, expensive, heavy magnets and magnet systems. A continuous transverse saturation level of magnetization is provided in the medium with virtually no vertical or longitudinal magnetic components or anomalous effects. A preferred arrangement comprises a number of wafer magnets each having an elongated edge of a pole face disposed proximate to the medium and at a preselected acute angle relative to the direction of intended movement of the magnetic medium.

Claims10

Dependent claims

Apparatus for applying magnetic fields to a magnetizable medium to render same substantially uniformly magnetized in one direction across and parallel to the medium and comprising:

a first plurality of magnets arranged in an array extending across the width of said medium and the magnetic fields created by each of said first plurality of magnets interact to effect a substantially uniform and continuous magnetic field in said one direction across said medium, and
a second plurality of magnets arranged in an array extending across the width of said medium and substantially parallel to said first plurality of magnets, the magnetic field created by said second plurality of magnets interact to effect a substantially uniform and continuous magnetic field in said one direction and also interact with the magnetic field created by said first plurality of magnets to substantially suppress components of said magnetic fields perpendicular to said medium while maintaining said magnetic fields created by said first and second plurality of magnets uniform and continuous and being substantially parallel to said medium to uniformly magnetize said medium in said one direction across the width of said medium as relative movement is affected between said medium and said first and second plurality of magnets.

Dependencies are inferred from the claim text.