Compagnie Internationale Pour L'informatique Cii-honeywell Bull (societe

Bull S.a.

Cii Honeywell Bull (societe Anonyme)

Compagnie Internationale Pour L'informatique

Bull S.a. (societe Anonyme)

Jacques Desserre

Michel Helle

Jean-Pierre Lazzari

Catherine Gueugnon

Pierre Bernstein

Jean-Claude Bouchand

Dominque Jeanniot

A substrate for perpendicular anisotropic magnetic recording comprises a nonmagnetic substrate (SUBSI) on which a thin metal magnetic medium (CMI) having a negative magnetostrictive effect is deposited. The direction of easy magnetization of the medium is perpendicular to the surface. In order to minimize the magnetostrictive effect in the metal magnetic medium, the medium comprises a stack of alternate thin magnetic and nonmagnetic layers (CI.sub.1 -CI.sub.n, ISO.sub.1 -ISO.sub.n-1), the nonmagnetic layers (ISO.sub.1 -ISO.sub.n-1) being sufficiently flexible so as to dampen the effect of the strains in the magnetic layers and enable strong magnetic coupling between them. The thickness of the nonmagnetic layers is between 150 and 250 angstroms, while the thickness of the magnetic layers is between 700 and 2000 angstroms. The stack may include as many as 10 or more magnetic layers of a chrome/cobalt alloy. The nonmagnetic layers may be SiO, SiO.sub.2 and mixtures thereof. The invention is applicable to magnetic recording disks.

Perpendicular anisotropic magnetic recording

A magnetic transducer for writing and reading data on a perpendicular recording carrier such as a magnetic disk includes a writing pole (MPOLI.sub.1) perpendicular to the recording carrier and a coil (BOBI.sub.1) magnetically coupled to a writing pole, each turn cross section of the coil being perpendicular to the carrier. The coil comprises a spiral with a flat development parallel to the carrier, disposed about and in the vicinity of the end of the writing pole (MPOLI.sub.1) that is located facing the carrier.

Magnetic reading/writing transducer for perpendicular recording

A device and method for writing data on a magnetic medium (SMI) are disclosed for use in connection with a recording layer (CMI1) made from an anisotropic material having the axis of easy magnetization perpendicular to its surface and which moves past at least one magnetic writing transducer (TMI). According to the invention, this device is characterized by the fact that the transducer comprises two adjoining writing poles (PEI1, PEI2) having opposite polarities and supplying simultaneously, in a direction (Oz) parallel to the surface of the layer and perpendicular to the base material's direction of motion, magnetic writing fields (Hy) which are normal to the surface of the layer with opposite polarity. The device is particularly applicable for writing data on a magnetic disc adapted for opto-electronic readout.

Device for writing high density data on a magnetic medium

A magnetic transducer is proposed for transverse recording on at least one track (PI.sub.1) of a data carrier (SMI.sub.1), comprising a magnetic circuit embodied by at least one writing pole (DCI.sub.1) coupled with a coil (BOBI.sub.1). According to the invention, the writing pole is a central pole surrounded by two auxiliary lateral poles (PLI.sub.1.1 and PLI.sub.1.2), separated from each of them by an air gap (ENI.sub.1, ENI.sub.2) such that the central pole records each cell of a given track with a given direction of magnetization, and the auxiliary poles record, on both sides of this cell, two lateral cells the magnetization of which is parallel and in the same direction and is opposite that of the central cell. The invention is applicable to magnetic disks.

Magnetic writing transducer for transverse recording

A transducer for writing data on a magnetic carrier includes a magnetic circuit having a writing pole piece (PPI.sub.2), realized in thin magnetic layers of anisotropic magnetic material. A conductor (CMPI) for controlling the writing is coupled magnetically with the pole piece and acts upon the pole piece for writing a datum by reversing the magnetization. A second control is magnetically coupled with the pole piece (PPI.sub.2), but does not act upon the pole piece except in the case of non-writing by diminishing the effective action of the conductor control.

Magnetic transducer for high density recording or writing

A magnetoresistant transducer for reading data present on the tracks of a multitrack magnetic carrier, comprises at least one magnetoresistant element perpendicular to the direction of travel of the data, and first and second magnetic screening means situated at either side of the element. The magnetoresistant transducer comprises deflecting means for deflecting the magnetic field generated by the current flowing through the element. The deflecting means are situated between the latter and the first and second screening means to intercept and deflect the magnetic field lines transmitted by the data items on the track. The deflecting means includes a plurality of mutually parallel thin magnetic blades separated from each other by thin non-magnetic laminations the thickness of which is such that the magnetic coupling between two adjacent laminations is weak. The laminations and magnetoresistances are of anisotropic material and have their axes of easy and difficult magnetization parallel to each other.

Magnetoresistant transducer

A magnetic transducer for reading magnetic information from a magnetic support such as a disc or tape which moves before it, comprises a magnetic circuit formed of two thin layer polar pieces having a gap at one end and means coupled magnetically to the circuit for transformation of magnetic flux loss of information into an electric signal. The pole pieces comprise at the level of the gap a central part bounded by two lateral parts spaced such that the magnetic coupling between the central parts is very much less than the magnetic coupling between the corresponding lateral parts of the pieces. The gap disposed between the central parts is larger than the gap of the lateral parts. There is a substantial reduction in Barkhausen noise and parasitic edge effects over conventional transducer constructions which is obtained by making the thickness of the pole pieces of the transducer substantially greater in the area of the geometric path Lpm than at the lateral portions beyond Lpm.

Integrated magnetic transducer

Transducer intended for read/write functions on a magnetic data carrier wherein the data is contained within a plurality of tracks. The transducer includes a magnetic circuit formed by two pole pieces separated by a gap parallel to the carrier, having its larger dimensions perpendicular to the direction of travel of the data of a track and a winding coupled magnetically to this circuit. The larger dimension of the gap varies depending on the nature of the function performed by the transducer. At least one thin layer of magnetic material is deposited across the pole pieces at each outer edge thereof and spaced from each other. The magnetic layers may be deposited in recesses formed in the pole pieces. The pole pieces may be constricted and include thin magnetic layers deposited on the lateral surfaces to channel magnetic flux lines.

Magnetic transducer comprising a gap of variable larger dimension for

Transducer intended for read and/or write functions on a magnetic data carrier wherein the data is contained within a plurality of tracks. The transducer includes a magnetic circuit formed by two pole pieces separated by a gap parallel to the carrier, having its larger dimension perpendicular to the direction of travel of data on a track and a winding coupled magnetically to this circuit. The transducer is characterized in that it comprises means associated with the pole pieces situated at either side of the gap as seen in the direction of its larger dimension, for channelling the magnetic flux emitted by the immediate magnetic surroundings of the track of the carrier read by the transducer.

Magnetic transducer for reading and/or recording of data contained on a

A magnetic transducer for reading and/or writing data contained on a carrier comprises two thin magnetic layers constituting the first and second pole pieces of the transducer. The layers are superimposed and magnetically coupled at one end and arranged at the other end adjacent the carrier, substantially perpendicular to the latter to form an air-gap to establish a magnetic circuit for the transducer. A coil is disposed between the thin magnetic layers. The coil is of thin conductive layers superimposed in a direction perpendicular to the plane of the magnetic layers and separated from each other by thin electrically insulating layers. The coil comprises windings of a number of turns N.sub.1 and N.sub.2 adapted to be traversed respectively by currents I.sub.1 and I.sub.2, the coefficients of mutual magnetic coupling of each of the thin conductive layers of each of the two windings with the downstream pole piece being respectively designated by L.sub.i1 and L.sub.j2 being such that: ##EQU1## whereby equal magnetic fluxes are created in the downstream pole piece, the downstream pole piece being defined as that pole piece which is last to be passed by a carrier moving substantially perpendicular to the plane of the layers and the air gap and successively past the first and second pole pieces.

A platform for supporting at least one magnetic transducer for reading from and/or recording on a data carrier. The platform is supported from a carrier arm adapted to position the platform over the data carrier which may be a multi-track disc. The magnetic transducer is supported in the lower face of the main body of the platform. The lower face includes a plurality of skids and one or more grooves which receive a rigid strut for suspending the platform over the carrier. The strut is secured in the groove (s) with the plane of the strut passing through the centers of gravity of the platform. The strut may be secured to a frame surrounding the platform which in turn may be secured to a further concentric frame also surrounding the platform.

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Rambouillet, France

Jacques Desserre