Sumitomo Special Metals Co., Ltd.

Citizen Watch Company, Ltd.

Sumitomo Special Metal Co. Ltd.

Junichi Nakaoka

Toshiaki Wada

Yoshiaki Katsuyama

Naoki Fujii

Toshikazu Hatsuse

Shigehiro Fuwa

Akio Murata

Masateru Nose

Masaru Ito

Takayuki Sugano

Takayuki Ono

A composite magnetic head is disclosed which is characterized by the fact that a magnetic head slider part and magnetic head core pieces both made of non-magnetic ceramic and provided on each of the opposed surfaces thereof with at least one layer of soft magnetic film produced in the form of sheet and subsequently shaped as required are integrally joined through the medium of glass members interposed between the opposed surfaces so as to give rise to a magnetic gap and an electromagnetic transducer coil is wound on the magnetic head core pieces. A composite magnetic head is further disclosed which is characterized by the fact that a magnetic head slider part and magnetic head core pieces, one made of an oxide magnetic material and the other made of a non-magnetic ceramic, are integrally joined through the medium of glass members interposed between pertinent opposed surfaces so as to give rise to a magnetic gap, the member made of the non-magnetic ceramic is provided on the opposed surface thereof with at least one layer of soft magnetic film produced in the form of sheet and subsequently shaped as required, and an electromagnetic transducer coil is wound on the magnetic head core pieces.

Composite magnetic head

A grooved magnetic substrate including an alumina film layer having a Knopp hardness of 600 kg/mm.sup.2 to 1200 kg/mm.sup.2 charged in at least one groove formed in a surface of a magnetic substrate. The magnetic substrate may be Mn-Zn or Ni--Zn base ferrite. The alumina film layer is formed by sputtering.

Grooved magnetic substrates and method for producing the same

A process for producing a substrate member for magnetic recording disc with improved surface state free of defects such as micropores and strain due to machining, and improved surface roughness, such substrate being obtained by first forming a glass coating layer on the surface of a substrate of an alumina-based ceramic material containing therein micropores of 5 .mu.m or less and having a relative theoretical density of 90% or above; then, subjecting the glass coating layer on a substrate to the hot isostatic pressing treatment; and further subjecting the surface of the glass coating layer to mechanochemical polishing to a layer thickness in a range of from 3 .mu.m to 200 .mu.m and the surface free from micropores and strain. Glass coating may be done by glazing or vapor deposition like sputtering.

Process for producing substrate member for magnetic recording disc

An improved magnetic recording disc comprising: a substrate member of an alumina-based ceramic material having micropores of 5 .mu.m or below and having a relative theoretical density of 90% or higher; a glass coating layer of a thickness of 3 to 200 .mu.m with a surface roughness (R.sub.z) of 180 angstroms or below, and being free from micropores and strain; a magnetic thin film formed on the surface of the glass coating layer; and a protective film formed thereon. A process for production of the magnetic recording disc comprises: forming a glass coating layer to a thickness of 5 to 220 .mu.m on the surface of an alumina-based ceramic substrate having micropores of 5 .mu.m or below and a relative theoretical density of at least 90%; then subjecting the glass coating layer to mechanochemical polishing to a layer thickness of 3 to 200 .mu.m, to make free from micropores and strain, and to have a surface roughness (R.sub.z) of 180 angstroms or below; and further coating the surface of the glass coating layer with a magnetic thin film and a protective film.

Magnetic recording disc and process for producing the same

An arrangement for mechanically processing a workpiece having a position detecting pattern or patterns formed thereon has a mechanically processing tool disposed at a predetermined position, a worktable arranged so as to be linearly moved in at least one of the rectangular coordinate X- and Y-axes while holding the workpiece thereon, and a position aligning unit provided with an opto-electric line sensor capable of detecting one of the patterns of the workpiece and issuing pattern detected signals, and an operation/control unit capable of mathematically processing the detected signals from the line sensor to determine a position of the workpiece to be mechanically processed and generating control signals for controlling the movement of the worktable so that the position to be mechanically processed is aligned with the position of the mechanically processing tool. The line sensor may be a CCD type line sensor.

Arrangement for mechanically and accurately processing a workpiece with

A grooved magnetic substrate including an alumina film layer having a Knoop hardness of 600 kg/mm.sup.2 to 1200 kg/mm.sup.2 charged in at least one groove formed in a surface of a magnetic substrate. The magnetic substrate may be Mn-Zn or NiZn base ferrite. The alumina film layer is formed by sputtering.

A substrate member for recording disk characterized in that a glass coating film is provided on an alumina base ceramic material having micropores of no larger than 5 microns and a relative theoretical density of no less than 96%, said glass coating film having a surface roughness of no more than 80 angstroms, being substantially pore-free and strain-free on the surface, and having a thickness of 0.3 to 200 microns and a relative difference of no more than 10.sup.-6 /deg in the coefficient of thermal expansion with respect to said base material.

Recording disk substrate members and process for producing same

A grooved magnetic substrate for thin film magnetic heads having grooves filled with glass having substantially no pores therein and an interdiffusion layer between substrate and glass of 5 microns or less. The substrate is produced by hot-filling the groove with glass at a viscosity of 10.sup.6 -10.sup.8 poise and subjecting the substrate to hot isostatic pressure at 10.sup.6 poise or higher to define a definite apex point to define the gap depth.

Growing community of inventors

Amagasaki, Japan

Junichi Nakaoka