Direct current bias fields for magnetic printing
AssigneeGeneral Electric Company
InventorsAmi E. Berkowitz, Joseph A. Lahut
Life of this patent
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Abstract
Recording head current in magnetic printing systems is reduced by application of a direct current magnetic bias field. The bias and recording fields add to produce a sum field with sufficient strength to switch a premagnetized recording medium. The bias field may be applied directly to the surface of the recording medium or may be concentrated at the recording medium surface by pin poles. In one embodiment of the invention the bias field is supplied by a permanent magnet common pole in a pin pole-type recording head array.
Claims19
A method of recording magnetic information on a sheet of magnetic recording medium comprising:
- premagnetizing said magnetic recording medium with a first magnetic field oriented in a first direction;
- biasing said magnetic recording medium with a second magnetic field, said second magnetic field being oriented in a second direction opposite to the direction of said first magnetic field, the strength of said second magnetic field being less than the strength necessary to saturate said recording medium;
- applying the poles of a recording head to said recording medium in the presence of said magnetic field;
- said poles defining a gap parallel to the direction of said second magnetic field;
- applying electric current to said magnetic recording head, said current being adapted to produce a third magnetic field across the gap of said recording head, the strength of said third magnetic field being less than the strength necessary to saturate said recording medium and the sum of the strength of said second magnetic field and the strength of said third magnetic field being sufficient to saturate said recording medium.
A structure for recording information in a sheet of magnetic recording medium, said recording medium having been premagnetized with a magnetic field of a first orientation in the plane of said sheet, comprising:
- means for applying a direct current magnetic bias field to said medium, said bias field having a magnitude less than the magnitude necessary to saturate said recording medium and further having an orientation opposite to the orientation of said premagnetized field;
- and
- a single turn, planar, recording head disposed in contact with said recording medium, the plane of said recording head being oriented normal to the orientation of said bias field, said head being adapted to selectively excite said recording medium with a recording magnetic field, said recording magnetic field having a force less than the force necessary to saturate said recording medium, the sum of the force of said recording magnetic field and the force of said bias magnetic field being sufficient to saturate said recording medium.
A structure for recording information in a planar sheet of magnetic recording medium, said medium having been premagnetized with a magnetic field in a first orientation in a plane of said sheet;
- comprising:
- means for applying a direct current magnetic bias field to said medium, said bias field further being oriented opposite to the orientation of said premagnetized field;
- and
- a plurality of magnetic recording heads, each of said heads including pin core members forming an acute angle within a plane lying normal to said sheet and parallel to said bias field, said recording head being adapted to excite said recording medium with a recording magnetic field having a magnetic force less than the magnetic force necessary to saturate said recording medium, the sum of the magnetic force of said recording magnetic field and the magnetic force of said bias field being sufficient to saturate said recording medium.
Dependencies are inferred from the claim text.