Mitsubishi Denki Kabushiki Kaisha

Japan Atomic Energy Research Institute

Hideo Ikeda

Yoshihiko Utsui

Chiyo Hamamura

Hiroshi Satoh

Hiroshi Sato

Takeshi Araki

Masashi Okabe

Masaharu Moriyasu

Masaru Okada

Megumi Ohmine

Hideyuki Yagi

Katsuyuki Ara

Naoki Yagi

Katsuhiko Honda

Toshitsugu Ohmura

Yoshihiro Tani

Hideshi Tsuchiya

Keiitiro Kobayashi

Tiyo Hamamura

Yoshiyasu Ogata

A thin film magnet and a cylindrical ferromagnetic thin film having a high maximum energy product (greater than 120 kJ/m.sup.3) and thus suitable for use in miniature high performance devices are provided. The thin film magnet is produced by means of physical vapor deposition. The thin film magnet is an (Nd.sub.1-x R.sub.x).sub.y M.sub.1-y-z B.sub.z alloy having a ferromagnetic compound of the Nd.sub.2 Fe.sub.14 B type as its main phase, wherein R is Tb, Ho, and Dy and M is Fe metal or an Fe-based alloy including at least one of Co and Ni, 0.04.ltoreq.x.ltoreq.0.10,0.11.ltoreq.y.ltoreq.0.15, and 0.08.ltoreq.z.ltoreq.0.15. A perpendicular magnetization film having such a composition is deposited on the side wall of a substrate in the columnar (or cylindrical) form thereby obtaining a cylindrical ferromagnetic thin film having radial anisotropy.

Thin film magnet, cylindrical ferromagnetic thin film and production

A strain detector in which a pair of magnetic layer patterns (5, 6) made of a magnetically permeable soft magnetic material are attached to a driven shaft (1) and a pair of detection coils (8, 9) are disposed to surround the respective magnetic layers for detecting a change in magnetic permeability of the magnetic layers which is caused when an external force is applied to the driven shaft. A magnetic yoke (15 or 16) is disposed around each of the detection coils (8 or 9) for promoting the passage of the magnetic flux therethrough, thereby decreasing flux leakage. The magnetic yokes (15, 16) each comprises an axially extending tubular member (15a) and radially inward outer and inner flanges (15d, 15e) extending from axially outer and inner ends of the tubular member, respectively. The magnetic yokes each may be made of a compacted core material containing magnetic powder and binder or assembled from a plurality of parts. A highly electrically-conductive, non-magnetic material (23) may be disposed directly between the inner ends (21b ) of the tubular member (21a) of the magnetic yokes (21) and the detection coils (8, 9) for magnetically isolating them without the need for any inner flange while allowing a compact structure.

Strain detector

A strain detector wherein the efficiency of a detecting coil is improved to improve the sensitivity of the strain detector. The strain detector comprises a magnetic layer made of a soft magnetic material having a high permeability and fixedly mounted on an outer periphery of a driven shaft strain of which is to be detected, and a detecting coil disposed around the magnetic layer with a gap left therebetween for detecting a variation of the permeability arising from strain of the magnetic layer caused by an external force applied to the driven shaft. The strain detector further comprises a metal layer made of a non-magnetic material having a high electric conductivity and disposed in the gap between the magnetic layer and the detecting coil. Or else, the detecting coil has a pair of coil portions connected to each other by way of an intermediate portion thereof, and an electric current flows in the same direction through the coil portions.

A method of manufacturing a heat resisting magnetic scale is disclosed which comprises a manufacturing process in which at least a part of a heat resisting base is heated and immediately cooled for the purpose of fusing the heated part to the base and changing both the magnetic characteristics of the part of the base which has been heated and the Curie point of the part which has been heated is raised to 100.degree. C. or higher.

Method of manufacturing heat resisting magnetic scale

A strain detector wherein external and internal magnetic fields are magnetically separated from each other to eliminate an influence of such disturbance magnetic field to assure accurate and stabilized detection of strain in a drive shaft. The detector comprises a magnetic layer made of a soft magnetic material having a high permeability and suitable magnetostriction fixedly mounted on an outer periphery of a driven shaft, a pair of bearings or bearing stands made of a soft magnetic material having a high permeability for supporting the driven shaft for rotation thereon, a detecting coil disposed around the magnetic layer for detecting a variation of the permeability of the magnetic layer arising from strain of the magnetic layer caused by an external force applied to the driven shaft, and a shield disposed on an outer periphery of the detecting coil and magnetically connected at the axial opposite end portions thereof to the bearings or bearing stands.

A strain detector for detecting a strain developed in a shaft applied with a torque comprises strain-sensitive magnetostrictive elements attached to the shaft in two groups in a chevron pattern. A pair of annular detection coils are wound around a bobbin to surround respective one of the groups of magnetostrictive elements. Two annular yokes made of a soft magnetic material of high permeability are disposed around respective coils across radial gaps. A hollow cylindrical shield of non-magnetic material with a high electrical conductivity is disposed around the two yokes across radial gaps. The magnetostrictive elements may be made of a nickel-iron alloy of 45 to 55% Ni-Fe. The yokes may be made of a nickel-iron alloy of about 80% Ni-Fe or alternatively, of a 6.5% Si-Fe steel. The detector may comprise a second magnetic shield disposed around the first shield of non-magnetic material with a high electrical conductivity. The second shield may be made of the same magnetic material as the yokes.

Strain detector with magnetostrictive elements

A speaker comprises a voice coil placed in an air gap between a center pole and a plate wherein a specific ferromagnetic material obtained by forming fine crystalline grains is used on at least one of the surfaces of the center pole and the plate which respectively face the voice coil, thereby providing a speaker having low distortion.

Growing community of inventors

Amagasaki, Japan

Hideo Ikeda