U.S. Philips Corporation

Gerrit J Koel

Jan T Gerkema

Frederik W Gorter

Lambertus Postma

Willem Frederik Druyvesteyn

Karel E Kuijk

Jan G Peelen

Frederik Ate De Jonge

Jan Willem Dorleijn

Theodorus C Bertens

Rene A Pluijms

Cornelis P Auwerda

Pieter Van Der Ree

While collapsing the central duct in hollow glass optical fiber preforms, an etchant consisting of a mixture of oxygen and a fluorocarbon compound from the group C.sub.2 F.sub.6, C.sub.3 F.sub.8 and N-C.sub.4 F.sub.10 is passed through the duct. In particular, the etchant is passed through the duct only when the duct's diameter is 1 mm or smaller. The resulting solid preforms and optical fibers drawn therefrom do not have a central dip in the refractive index profile.

Method of manufacturing an optical fiber preform

Optical fibres are manufactured by etching the inner wall of a tube. The tube wall is etched by passing a hydrogen-free fluorine compound through the tube while reciprocating a nonisothermal plasma through the tube. After etching, core glass is chemically deposited on the etched surface. The core glass is deposited from the gaseous phase while using a nonisothermal plasma for initiating the reaction. The inner-coated tube is then collapsed and drawn to form an optical fiber.

Method of manufacturing optical fibres

A memory device utilizing magnetic bubbles which are driven by a rotary magnetic field on contiguous disc drive patterns. These disc patterns have mainly a first scale. Each drive pattern also comprises a further disc pattern of a substantially larger scale. These further disc patterns each time comprise an excitation loop. These loops are mutually staggered with respect to the phase of the rotary field and are electrically connected in series. The series connection can be excited during relevant phases of the rotary magnetic field in order to selectively process a bubble then present in a locally formed preferred position from among the magnetic bubbles present on the larger disc patterns. The processing operation may be generating, detecting and annihilating bubbles.

Device for generating magnetic bubbles with a high bit rate

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

In the electrodeposition of nickel-iron alloy layers during the manufacture of a thin-film magnetic head it is ensured that the nickel-iron alloy layer has a top layer having a higher iron content than the iron content of the remainder of the nickel-iron alloy layer. Since this top layer etches more rapidly than the remainder of the layer, the nickel-iron alloy layer itself becomes sloped during etching, this sloping configuration presents great advantages in the subsequent coating with a layer of silicon dioxide.

Method of manufacturing a thin-film magnetic head with a nickel-iron

A method of manufacturing a magnetic head wherein a pattern is formed in a nickel-iron layer by means of a photo-etching process. The nickel-iron layer is provided with an auxiliary layer of titanium, titanium oxide or silicon oxide and with a photolacquer layer in a pattern which corresponds to the pattern desired in the nickel-iron layer. The lacquer layer pattern does not cover a part of the auxiliary layer and serves as an etching mask for the simultaneous etching of the auxiliary layer and the nickel-iron layer.

Method of manufacturing a magnetic head by photo-etching

A method of making inclined sides on a metal pattern which is grown on a substrate by electroplating as a preliminary measure to the coating of the substrate with the metal pattern by an insulating layer. The main deposition of the insulating layer by sputtering is preceded by a sputter-etching step which transforms the rounded edges of the metal pattern into inclined sides.

Forming electrically insulating layers by sputter deposition

A method of manufacturing a device in which a conductive base pattern is formed on a substrate and is reinforced by electroplating so as to obtain a conductor pattern, characterized in that at least a surface layer of the substrate consists of an electrically insulating material on which an auxiliary layer is provided having a sheet resistance between 10.sup.12 and 10.sup.17 ohms per square, after which the base pattern is formed on the last-mentioned layer.

Method of reinforcing a conductive base pattern by electroplating and

A thin-film magnetic head in which the electrically conductive magnetic material of the core is wound directly a number of times around an electrical conductor which ensures the energization of the head presents the advantage that the manufacture can take place by means of exclusively electroplating methods, since in this configuration no insulating layers are necessary between the material of the core and the conductor.

Magnetic head having a core provided on a substrate by means of

A magnetic head for use in a magnetic reproduction device has a substrate in which a groove is provided. Provided on one wall of the groove is a magnetic field-sensitive element which is preferably positioned normal to an associated recording medium for coupling to the magnetic head.

Magnetic head using a magnetic field-sensitive element and method of

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 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.

The invention relates to a device for magnetic recording which is provided with a layer of a magnetizable material which is provided on a support and has an easy axis of magnetization which is at least substantially perpendicular to the plane of the layer, which layer is suitable to support magnetic domains having a direction of magnetization which is opposite to the direction of magnetization of the remainder of the layer, the device also comprising a device for producing a magnetization field having a field direction perpendicular to the plane of the layer, said layer being destined to cooperate with a recording medium which is relatively movable with respect to the layer.

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Eindhoven, Netherlands

Gerrit J Koel