U.S. Philips Corporation

Gerardus H Somers

Jacobus J Ruigrok

Lambertus Postma

Jan Haisma

Victor Zieren

Antonius B Voermans

Henricus G Maas

Johann R Van Beek

Rudolf A Van Doorn

Franciscus A Pronk

Antonius C Gieles

Eduard E Gillissen

James Richard Peterson

Helmut J Gassen

Wilhelmus J Smits

Arie J Van Straalen

Mathijs Antonius Karsmakers

P Michalek

Johannes F De Proost

Johannes H Franssen

System comprising a magnetic head (1) and a measuring device connected to the magnetoresistive element. The magnetic head has a head face (5) with a transducing gap (15) and comprises a magnetoresistive element (13) and a magnetically conducting yoke with an electrically conducting element (11a) for generating a magnetic field intersecting the magnetoresistive element. The system also comprises a current device connected to the electrically conducting element.

System comprising a magnetic head, measuring device and a current device

Method of manufacturing a thin-film magnetic head provided with a transducing element (23) and at least one flux-guiding element (17a, 17b). An electrically conducting layer (8) of a non-magnetic material and a second electrically insulating layer (9) of a non-magnetic material are successively formed on a first electrically insulating layer (5) of a non-magnetic material. The second electrically insulating layer is subsequently provided with at least an interruption exposing a portion of the electrically conducting layer. Subsequently, the flux-guiding element is formed by electrodepositing a soft-magnetic material on said portion until the interruption is filled, whereby the flux-guiding element and the second electrically insulating layer constitute an at least substantially plane surface on which an electrically insulating spacer layer (21) is formed. Subsequently, the transducing element is provided on the spacer layer. The magnetic head thus formed has a non-magnetic transducing gap (35) terminating in a head face (33) and being constituted by the first electrically insulating layer (5) and the electrically conducting layer (8).

Method of manufacturing a thin-film magnetic head, and magnetic head

Apparatus for recharging a battery, comprising a compartment which holds the battery so that its electrical terminals are in contact with a pair of electrodes. The electrodes are connectable to the poles of a controllable source of electrical energy. In the compartment a ferromagnetic body is positioned so as to be subjected to mechanical stress in response to mechanical deformation of the battery. An electrical device monitors the magnetic permeability .mu. of the ferromagnetic body by measuring the self-inductance of a coil surrounding at least a portion of the ferromagnetic body. The .mu. of the ferromagnetic body changes by magnetostrictive effects arising from mechanical stress of the ferromagnetic body in response to mechanical deformation of the battery (5) during charging. Expansion of the battery can be used as an indicator that charging has been completed, and that the battery should be disconnected from the source of electrical energy.

Apparatus for recharging a battery

Method of manufacturing a thin-film magnetic head in which a main layer (5) of a non-magnetic material is formed on a support, which layer is recessed by removing material from a side remote from the support, said recess being subsequently filled up with a soft-magnetic material for forming a flux guide (17a, 17b), whereafter the main layer provided with the filled recess is mechanochemically polished for forming a main surface (19) at which subsequently a layer of a magnetoresistive material is provided for forming a magnetoresistive element (23).

Method of manufacturing a thin-film magnetic head

Method of manufacturing a magnetoresistive magnetic head in which a first insulation layer (5) of a non-magnetic material is formed on a support face (3a), on which insulation layer a soft-magnetic layer having an upper face remote from the first insulation layer is formed by deposition of a soft-magnetic material. Subsequently a layer portion is removed for forming the flux-guiding elements (17a, 17b) and an aperture extending between said elements, and non-magnetic material for forming a second insulation layer (18) having an upper face remote from the soft-magnetic layer is deposited on the soft-magnetic layer and in the aperture formed therein, which second insulation layer has such a thickness that, viewed in a direction transverse to the support face, the smallest distance between the support face and the upper face of the second insulation layer is larger than the largest distance between the support face and the upper face of the soft-magnetic layer. Subsequently, a mechanochemical polishing treatment is performed as from the upper face of the second insulation layer for forming a main surface (19) at which magnetoresistive material is subsequently deposited for forming a magnetoresistive element (23).

A thin-film magnetic head is situated on a carrier (2) on which an electrically conducting plating-base (2) is provided on which by electroplating flux conductors and a magnetically insulating layer (8) are grown. This provides a planar structure on which an electrically insulating layer and a magneto-resistance element are provided. The plating-base also constitutes the gap layer.

Thin-film magnetic head having an electrically conducting plating base

A magnetic head (1) for reading information comprises a magnetoresistive element (21) which is arranged between two flux guides (7, 9) present on a support and is partly located on thinner ends (25, 27) of the flux guides. The flux guides are composed of a basic layer (13, 15) and a main layer (17, 19) which partly covers the basic layer. Subsequently the magnetoresistive element is partly provided on the parts (25, 27) of the basic layer which have been left free by the main layer so that the magnetoresistive element is magnetically coupled to the flux guides via coupling parts (20, 22).

Magnetic head provided with a flux guide and a magnetoresistive element

A method of producing a thin-film magnetic head on a carrier (1) comprising depositing an electrically conducting plating-base (2) and electroplating flux conductors (4a, 4b) and a magnetically insulating layer (8) on the plating-base. This provides a planar structure on which an electrically insulating layer (9) and a magneto-resistance element (10) are applied. The plating-base (2) also constitutes the gap layer.

Method of producing a thin-film magnetic head utilizing electroplating

With a thin-film magnetic head (20) having a flux conductor (21) and a magneto-resistance element (28) the flux conductor is divided into a plurality of flux conductor portions (23) which are spaced apart along the length (25) by a distance (27). This accomplishes a decrease in the mechanical tensions in the flux conductor (21) as a result of which a signal to be read is distorted to a lesser extent.

Thin-film magnetic head

Thin-film magnetic head comprising a substrate (2), an inductive element (23) and a magnetoresistive element (7), and substantially parallel extending flux guides of a magnetic conducting material for magnetic cooperation with said elements. The flux guides are mutually arranged in such a way that two pairs of flux guides (3A, 3B; 5A, 5B) mutually separated by an insulation layer (19) of a non-magnetic material are present, a first pair constituting a first magnetic circuit, provided with a write gap (27), for the inductive element and a second pair constituting a second magnetic circuit, provided with a read gap (17), for the magnetoresistive element.

Combined read/write thin film magnetic head with two pairs of flux guides

For a tape contact face to be formed in a thin-film magnetic head having at least one transducing element, by removing material, a reference plane (29) corresponding to the tape contact face is detected by means of a plurality of markers (27A-27J) juxtaposed in a layer and extending transversely to the tape contact face, which markers have first end portions (27A1-27J1) pointing in one direction and second, spatially separated end portions (27A2-27J2) pointing in an opposite direction, with the second end portions located at different distances from the reference plane, inclined with respect to the reference plane, and adjoining each other steplessly.

Method of manufacturing a thin-film magnetic head and magnetic head

A read head arrangement comprising n first read heads (h.sub.a.1, . . . , h.sub.a.n) and n second read heads (h.sub.b.1, . . . , h.sub.b.n) of the magnetoresistance type, n transistors (Tr.sub.1, . . . , Tr.sub.n) and switching means (S), where n is an integer greater than two. The first main electrode (collector) of a transistor (Tr.sub.i) is coupled to an i-th output (U.sub.i) of the arrangement. The second main electrode (emitter) of the transistor (Tr.sub.i) is coupled to a first terminal (t.sub.1) of a first read head (h.sub.a.i) and a second read head (h.sub.b.i). The second terminal (t.sub.2) of the first read head (h.sub.a.1) is coupled to a first terminal (a) of the switching means (S). The second terminal (t.sub.2) of the second read head (h.sub.b.1) is coupled to a second terminal (b) of the switching means (S), of which a third terminal (c) is coupled to a point of constant potential (earth), while i ranges from 1 to n.

Cassette recorder magnetic read head arrangement for autoreverse

A thin-film magnetic head comprises a magnetic yoke, having a first and a second flux conductor (1, 2) and a magneto-resistance element (4) remote from a head face (7). A first edge portion (4a) of the magneto-resistance element (4) is located closer to the head face (7) than a second edge portion (4b). The first flux condutor (1) extends from the head face (7) to close to the first edge portion (4a) and the second flux conductor (2) extends from the head face at least to the second edge portion (4b). Furthermore, the magnetic head includes a further magneto-resistance element (5) which forms part of the magnetic yoke and is located between the first and the second flux conductors (1, 2) at the head face (7).

Thin-film magnetic head having two magneto-resistant elements

A thin-film magnetic head comprises a magnetic yoke having first and second flux conductors (3, 4) and a magneto-resistance element (7), located remotely from a head face (1). An edge portion (7a) of the magneto-resistance element (7) is located closer to the head face (1) than a second edge portion (7b). The first flux conductor (3) extends from the head face (1) to close to the first edge portion (7a) and the second flux conductor (4) extends from the head face at least to the second edge portion (7b). The magnetic head furthermore comprises a third flux conductor (5) which extends from the head face (1) to close to an end portion (16) of the first flux conductor (3) located near the first edge portion (7b). A transducing gap (17) and an inductive element (9) are located between the first and the third flux conductors (3, 5).

Elongate magneto-resistive elements (3) spaced apart on a substrate (9) incorporated in a magnetic circuit constituted by a magnetic yoke (5, 7, 9) which is provided with pole faces (19, 21) for the purpose of co-operating with the registration medium, while each magneto-resistive element is provided with two contacts (3A) for connection to a measuring current source. To improve the stability of the magneto-resistive elements, the magnetic head has strip-shaped coupling elements (17) which magnetically couple the magneto-resistive elements and keep them electrically separated from each other.

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Eindhoven, Netherlands

Gerardus H Somers