Abstract: There is provided a reader for reading information magnetically coded on a carrier. The reader includes a magnetizing device for magnetizing the information precoded on the carrier and a transducer for detecting the magnetized information as the carrier is translated successively past the magnetizer and transducer. The magnetizer includes at least one magnetic layer having a succession of adjoining zones, the length of alternate zones being much greater than the length of the other zones and the magnetic induction in the zones being of opposite sense. The transducer includes at least one magneto-resistive detecting member and a magneto-resistive compensating member which are of anisotropic magnetic material. The members are disposed to develop across the compensating member a voltage in response to the interference magnetic field which is equal to that developed across the detecting member due to that field.

Abstract: The invention concerns an integrated magnetic head adapted to cooperate with a track of a very narrow width, f.i. of about 20 microns, of a recording medium which moves perpendicularly to said width in close proximity to the frontal gap face of the head. The frontal width of the pole-piece layers of the head is reduced after said layers have been formed with a larger width adapted to a normal electromagnetic efficiency of the head in the parts of the said pole-pieces which encase the front branch of its flat conductor winding coil. The reduction is obtained by removal of the lateral parts of the pole-pieces over a predetermined depth with respect to the frontal face. Any registering part of an intervening dielectric layer between the pole-piece layers for defining the magnetic gap of the head is simultaneously removed. It is important that the removal be made by an attack such as a ionic erosion process perpendicularly oriented to the frontal plane of the head.

Abstract: In magnetic disk equipment or the like, the read/write magnetic heads are each bonded to the wall of a thru-hole of a carrier plate adapted to act as a "flying" member maintained by an aerodynamical action in close proximity to the surface of the rotating disk. In a device according to the invention, the bond between the lateral surface of the head and said wall is made to ensure magnetostatic and electrostatic shielding of the head against spurious magnetic, electromagnetic and electrostatic fields. Said bond may comprise thin films of a high permeability anisotropic material coating at least the facing surfaces of the head and the wall and a layer of solder intervening between said films. Such a shield may partially extend over selected areas of the rear faces of the plate and head.

Abstract: The invention concerns an integrated magnetic head adapted to cooperate with a track of a very narrow width, f.i. of about twenty microns, of a recording medium which moves perpendicularly to said width in close proximity to the frontal gap face of the head. The frontal width of the pole-piece layers of the head is reduced after said layers have been formed with a larger width adapted to a normal electromagnetic efficiency of the head in the parts of the said pole-pieces which encase the front branch of its flat conductor winding coil. The reduction is obtained by removal of the lateral parts of the pole-pieces over a predetermined depth with respect to the frontal face. Any registering part of an intervening dielectric layer between the pole-piece layers for defining the magnetic gap of the head is simultaneously removed. It is important that the removal be made by an attack such as a ionic erosion process perpendicularly oriented to the frontal plane of the head.

Abstract: The invention provides a structure for a read-only integrated magnetic head which, without any recourse to a shield, ensures or at least enables the elimination from the read-out signal transferred from the head to the external circuits it must feed, any component which might be due to the application of spurious electromagnetic fields to the surface comprised by the flat conductor winding coil and to the surface intervening between the output leads of said coil up to the rear edge of the substrate which carries the integrated magnetic head.An additional flat conductor winding coil is provided over the read-out coil. Said two coils register but they are mutually magnetically decoupled, by means for instance of an intervening non-magnetic dielectric layer of appropriate thickness.

Abstract: In magnetic disk equipments or the like, the read/write magnetic heads are each bonded to the wall of a thru-hole of a carrier plate adapted to act as a "flying" member maintained by an aerodynamical action in close proximity to the surface of the rotating disk. In a device according to the invention, the bond between the lateral surface of the head and said wall is made to ensure magnetostatic and electrostatic shielding of the head against spurious magnetic, electromagnetic and electrostatic fields. Said bond may comprise thin films of a high permeability anisotropic material coating at least the facing surfaces of the head and the wall and a layer of solder intervening between said films. Such a shield may partially extend over selected areas of the rear faces of the plate and head.

Abstract: In a thin film magnetic writing head structure, a high permeability layer is arranged parallel to the lateral face of a pole piece which is situated in the downstream direction of movement of the magnetic record carrier under the head airgap. Said high permeability layer is magnetostatically de-coupled from the pole piece. This arrangement guides the zero magnetic field lines from the head along the frontal plane of the pole piece and along the lateral face of said piece, thereby drastically reducing the action of de-magnetizing components of the writing flux on the record.

Abstract: A magnetic circuit which exhibits low reluctance on the path of a magnetic flux and comprises at least one anisotropic thin film formed of an iron-nickel-chromium alloy through which said magnetic flux passes in the hard direction of magnetization of the film.

Abstract: An electromagnetic transducer based on the magnetoresistive effect is made of a stack of members each of which comprises a magnetoresistive layer enclosed, with interposition of non-magnetic insulating layer, between two thicker high permeability layers, so that these layers are in leakage field magnetostatic coupling. The members are stacked with interposition of non-magnetic layers such that they are in relative edge effect magnetostatic coupling relation. Each magnetoresistive layer has its easy magnetization axis 45.degree. to the direction of passage of an electrical current therethrough and said axes are 90.degree. to each other in any two of the consecutive members of the stack.

Abstract: A read-write transducer for magnetic recording is made of two plural magnetoresistive layer flat structures contacting each other at first ends thereof and spaced apart at the opposite ends thereof and of a flat conductor coil winding having a front branch inserted between the said spaced apart ends of the structures. The magnetoresistive layers of the stacks are electrically interconnected in a read-out circuit and the winding may receive writing electrical currents. Each magnetoresistive layer in a stack is inserted between two thicker high permeability magnetic layers and all layers in a stack are relatively insulated.

Abstract: A device for testing the magnetic properties of a magnetic material in which a measurement air gap and a measurement compensation air-gap, is established and a measuring coil is provided for collecting a voltage which is proportional to the variation of amplitude of the resultant useful flux derived from the magnetic material which is placed in the vicinity of the measurement air-gap.

Abstract: The open-loop magnetic circuit of an integrated magnetic head for reading and/or writing is made up of two magnetic films which are joined together at one end, the other end being placed in proximity to the writing and/or reading surface and substantially at right angles thereto. In order to form the electric winding for writing and/or reading, the magnetic head comprises within said loop and in an alternate arrangement a succession of electrically conducting and electrically insulating film layers which are at least partially superposed in a direction substantially at right angles to the plane of the two magnetic films.