U.S. Philips Corporation

Frederik W Gorter

Jan T Gerkema

Gerrit J Koel

Jan Antoon Potgiesser

Karel E Kuijk

Jacobus J Ruigrok

Henricus Petrus Wijn

Jean-Paul G Morel

A core of a soft-magnetic material with a comparatively low saturation magnetization has layers of a soft-magnetic material with a higher saturation magnetization on the gap-bounding faces. To compensate for the uneven frequency response cause by the non-magnetic transition zones between the material of the core and the layers of soft-magnetic material, the layers of soft-magnetic material on the gap-bounding faces have different thicknesses.

Magnetic write head with smooth frequency response

A thin-film magnetic head for writing information in and reading information from a track of a magnetic recording medium in which the head comprises a magnetically permeable yoke having two limbs between which a writing/reading gap is formed. In a construction in which the limbs of the yoke overlap each other at the area of the writing/reading gap, they are bridged by a magneto-resistive reading element at a location remote from the reading/writing gap. A conductor is provided in some forms of the invention which extends intermediate the laterally overlapping limbs. This conductor is utilized for producing a writing flux in the magnetic yoke. Another conductor may be provided which extends through a window or opening in the yoke, which is remote from the reading/writing gap. This other conductor is utilized during writing operation to maximize efficiency.

Thin-film magnetic head for reading and writing information

A thin-film magnetic head for writing information in and reading information from a track of a magnetic recording medium in which the head comprises a magnetically permeable yoke having two limbs between which a writing/reading gap is formed. In a construction in which the limbs of the yoke are opposite to each other, one limb is interrupted by a gap which is bridged by a magneto-resistive reading element.

A magnetic reading device having two electrically series-arranged magnetoresistive elements, in particular for interference compensation and positioning control. A pattern of equipotential strips is provided on each element to adjust the quiescent angle .alpha. between the direction of magnetisation and the direction of current passage of one element between 30.degree. and 60.degree. and between 210.degree. and 240.degree., respectively, and that of the other element at 360.degree. - .alpha. and 180.degree. - .alpha., respectively, the device has for various applications an automatic compensation of the signals across the elements so that the use of difference amplifiers is superfluous. In addition, due to this adjustment, the reproduction characteristics has a linear variation.

Magnetoresistive head

A magnetic reading head having a magneto-resistive element of the non-magnetically biased type, in which the current is forced to flow through the element at an angle with the easy axis of magnetization. For adjusting the dynamic range of the element, the element is subjected to a variable strength auxiliary field having a direction of which is parallel to the easy axis of magnetization.

Variable dynamic range magneto-resistive head

A thin-film magnetic head for writing information in and reading information from a track of a magnetic recording medium in which the head comprises a magnetically permeable yoke having two limbs between which a writing and reading gap is formed. In a construction in which the limbs of the yoke are opposite to each other, one limb is interrupted by a gap which is bridged by a magneto-resistive reading element. In a construction in which the limbs of the yoke overlap each other at the area of the writing/reading gap, they are bridged by a magneto-resistive reading element in another place.

A thin-film magnetic head having improved playback properties in which the gap-bounding core parts overlap each other laterally while enclosing a layer having a gap and in which a first core part has the shape of a closed loop and is bridged in the center by a second core part. The parts of the first core part on either side of the bridge are provided with identical coils, while the first core part at the area of the overlap is divided centrally by an extra gap. Upon playing back, the difference signals of the coils then provides an indication as regards the position relative to the track.

Thin film magnetic head with a gap formed between a loop shaped core

A magnetic head having a magnetoresistive element. The element comprises a center tap, while on the left-hand half a pattern of equipotential strips is provided at an angle with the longitudinal direction of approximately 45.degree. and on the right-hand half a pattern of equipotential strips is provided at an angle of approximately 135.degree. with the longitudinal direction. The halves are each controlled with a current source and their output signals are subtracted from each other. The relation between the resistance of the total element and the value of external magnetic fields is more linear than in known magnetic heads having a magnetoresistive element and thermal noise is eliminated.

Magnetoresistive magnetic head

A magnetoresistive detection device for determining the presence or absence of a single-wall magnetic domain at a position in a thin layer of magnetic material in which stable single-wall magnetic domains can be moved, comprising a sensing element of magnetoresistive material which is provided with respect to the layer of magnetic material in such manner that the resistance thereof varies when a single-wall magnetic domain is present at the said position. The device comprises means to produce an alternating magnetic field so as to modulate the size of a single-wall magnetic domain present at the said position, and comprises a filter which passes only interference-free terms of the signal detected by the sensing element.

Magnetoresistance detection device having noise suppression

A magnetic head utilizing the magneto-resistive effect with at least two magneto-resistive elements present in one plane at right angles to the recording medium. The elements are connected to an output circuit in which their signals are subtracted from each other. In this manner compensation is provided for both interference signals and crosstalk signals. The head may comprise a reading element and a compensation element arranged above it or a reading element flanked by two compensation elements with a larger distance to the recording medium or with a smaller height.

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Eindhoven, Netherlands

Frederik W Gorter