Toda Kogyo Corporation

Takanori Doi

Kousaku Tamari

Tetsuya Kimura

Jun Koujima

Kenichi Nakata

Yoshiro Sato

Yasuo Kakihara

Yoji Okano

Kazumi Yamamoto

Tomohiro Dote

Setsuo Yamamoto

Mitsuru Matsuura

Masaaki Maekawa

Teruaki Santoki

An object of the present invention is to provide a ferrite material that is excellent in temperature characteristic and DC superimposition characteristic. The present invention relates to Ni&#x2014;Zn&#x2014;Cu-based ferrite particles comprising 70 to 95% by weight of an Ni&#x2014;Zn&#x2014;Cu ferrite having a specific composition, 1 to 20% by weight of nickel oxide, 0 to 20% by weight of zinc oxide and 1 to 10% by weight of copper oxide, and a ferrite sintered ceramics obtained by sintering the ferrite particles.

Ni&#x2014;Zn&#x2014;Cu-based ferrite particles, green sheet comprising the Ni&#x2014;Zn&#x2014;Cu-based ferrite particles and Ni&#x2014;Zn&#x2014;Cu-based ferrite sintered ceramics

The present invention relates to a folded dipole antenna comprising a magnetic material comprising a hexagonal Z-type ferrite and/or a hexagonal Y-type ferrite as a main component in which a radiation element and a reflection element each having a folded dipole structure are disposed, and an RF tag comprising the folded dipole antenna and an IC chip connected to the folded dipole antenna. The RF tag according to the present invention has a smaller size than that of the conventional RF tags and is not susceptible to adverse influence from ambient environments, and can be operated at an UHF band or surrounding frequency bands thereof.

Folded dipole antenna and RF tag using the folded dipole antenna

The present invention relates to a magnetic antenna for information communication using a magnetic field component which is capable of satisfying both reduction in size and improvement in communication sensitivity. The magnetic antenna of the present invention is used for transmitting and receiving information using an electromagnetic induction method, and comprises a central core formed of a magnetic material and a non-magnetic material, a coil-shaped electrode material wound around the core, and an insulating layer formed on at least one outside surface of the core on which the coil-shaped electrode material is provided, in which the magnetic material is separated into two or more parts through the non-magnetic material when viewed in a section of the core which is perpendicular to a magnetic flux passing therethrough.

Magnetic antenna, board mounted with the same, and RF tag

The present invention relates to a molded ferrite sheet having opposing surfaces and a thickness in a range of 30 &#x3bc;m to 430 &#x3bc;m, at least one surface of said opposing surfaces having the following surface roughness characteristics (a) to (c):

Molded ferrite sheet, sintered ferrite substrate and antenna module

The present invention relates to a composite RF tag for transmitting and receiving information using an electromagnetic induction method, comprising a magnetic antenna mounted with an IC, and a resin layer formed around the magnetic antenna, wherein the magnetic antenna comprises a central core formed of a magnetic material and a coil-shaped electrode material disposed around the core. The RF tag according to the present invention comprises the magnetic antenna surrounded by the resin, and therefore can provide a composite magnetic RF tag which can minimize adverse influence by surrounding water or metals in view of maintenance of tools or parts to which the composite RF tag is mounted, and is free from occurrence of any failure or cracking.

Composite RF tag, and tool mounted with the composite RF tag

A composite magnetic antenna for information communication utilizes a magnetic field component as well as a composite RF tag using the composite magnetic antenna, which can be embedded in metals while maintaining a sufficient communication sensitivity unlike conventional RF tags which are unusable in the metal embedding applications. The composite RF tag for transmitting and receiving information using an electromagnetic induction method includes a magnetic antenna on which an IC is mounted, and an insulating material and a metal material or a conductive material which are formed around the magnetic antenna. The magnetic antenna includes a central core formed of a magnetic material, and an electrode material formed into a coil around the central core. The insulating material is formed around the magnetic antenna except for one longitudinal end of the coil of the magnetic antenna. The metal material or the conductive material is formed on an outside of the insulating material.

Composite magnetic antenna and RF tag, and metal part and metal tool on which the composite magnetic antenna or RF tag is installed

A perpendicular magnetic recording medium, comprises a substrate; a soft-magnetic layer formed on the substrate; an NaCl-type oxide layer for orientation control formed on the soft-magnetic layer, having a thickness of from more than 0 to less than 10 nm; and a magnetic recording layer formed on the NaCl-type oxide layer for orientation control, comprising a maghemite thin film. Such a perpendicular magnetic recording medium is capable of showing excellent magnetic properties, a high recording resolution and improved surface properties.

Perpendicular magnetic recording medium

A magnetic recording medium exhibiting a high coercive force and excellent squareness having a substrate, an underlayer formed on the substrate, and a spinel-type iron oxide thin film with maghemite as a main component formed on the underlayer. The spinel-type iron oxide thin film has a thickness (t) of 5 to 50 nm, is constituted by grains having an average grain size (D) of 5 to 30 nm, standard deviation of sizes of grain of not more than 4 nm and a ratio (D/t) of the average grain size (D) to the thickness (t) of less than 1.0, exhibits a coercive force of not less than 159 kA/m (2,000 Oe) and a coercive squareness ratio S* of not less than 0.5:1 in a longitudinal recording medium or a squareness ratio not less than 0.75:1 in a perpendicular recording medium.

Magnetic recording medium and process for producing the same

A magnetic recording medium is prepared by forming on a plastic substrate, a nickel oxide underlayer having a plane (200) which is predominantly oriented in parallel with the surface of the plastic substrate, then forming on the nickel oxide underlayer at a substrate temperature of less 240&deg; C., a cobalt-containing magnetite thin film having a plane (400) which is predominantly oriented in parallel with the surface of the plastic substrate, and finally oxidizing the cobalt-containing magnetite thin film in a plasma-activated oxygen atmosphere containing a rare gas at a substrate temperature of less than 240&deg; C. while incorporating the rare gas into oxygen. This results in a cobalt-containing maghemite thin film as a perpendicular magnetic film having a spacing of a plane (400) of not more than 2.082 &angst;. The magnetic recording medium so produced is useful for high-density recording using a plastic substrate.

Process for producing magnetic recording medium

A magnetic recording medium of the present invention comprises: a plastic substrate; and a cobalt-containing maghemite thin film formed on said substrate, containing cobalt at a molar ratio of cobalt to iron of not more than 0.06:1, and having either a spacing of a plane (,) of not more than 2.510 &angst;, a spacing of a plane (,) of not more than 2.415 &angst; or a spacing of a plane (,) of not more than 2.950 &angst;; and has a coercive force of not less than 2,000 Oe. Such magnetic recording medium suitably applicable to existent magnetic recording systems using a ring-type magnetic head and capable of using a plastic substrate for providing a magnetic recording medium for high-density recording.

A magnetic recording medium of the present invention comprises: a substrate; and a cobalt-containing maghemite thin film formed on said substrate, containing cobalt at a molar ratio of cobalt to iron of not more than 0.06:1, having either a spacing of a (311) plane of not more than 2.510 .ANG., a spacing of a (222) plane of not more than 2.415 .ANG. or a spacing of a (220) plane of not more than 2.950 .ANG., and having a coercive force of not less than 1,800 Oe. Such a magnetic recording medium has as high a coercive force as possible, specifically not less than 1,800 Oe, and exhibits an excellent stability independent to change in passage of time and a large output in a high recording frequency region.

Magnetic recording medium

A magnetic recording medium of the present invention comprises: a substrate; a nickel oxide underlayer formed on said substrate; and a cobalt-containing maghemite thin film formed on said nickel oxide underlayer, having either a spacing of a (311) plane of not more than 2.510 .ANG., a spacing of a (222) plane of not more than 2.415 .ANG. or a spacing of a (220) plane of not more than 2.950 .ANG., and having the ratio of either of X-ray diffraction spectrum peak intensities of the (311), (222) or (220) planes of said cobalt-containing maghemite thin film to an X-ray diffraction spectrum peak intensity of the (400) plane of more than 0.5:1. Such a magnetic recording medium has a higher coercive force, a higher saturation magnetization, less amount of noise generated, a large output in a high recording frequency region and less distortion of a reproduced waveform, and is suitable for use in current magnetic recording systems in which a ring-type magnetic write head is used.

Growing community of inventors

Hiroshima-ken, Japan

Takanori Doi