Sumitomo Special Metal Co. Ltd.

Sumitomo Special Meter Co., Ltd.

Sumotomo Special Metal Co., Ltd.

Youichi Ohnishi

Hideya Sakurai

Toshinobu Miyamoto

Hiroo Hayashi

Masaaki Aoki

Hirofumi Takabayashi

Disclosed is an MRI-dedicated magnetic field generating device for generating magnetic fields within an air gap, including: a pair of permanent magnet assemblies opposite to each other to form an air gap therebetween; yokes for magnetically linking the permanent magnet assemblies; and magnetic pole pieces fixed to air-gap-confronting surfaces thereof. Based on this construction, intensities of the magnetic fields are increased by disposing a plurality of magnetic material segments on the same circle or a concentric circle on the confronting surface thereof or decreased by disposing a plurality of permanent magnet segments having a magnetizing direction opposite to that of the permanent magnet assemblies on the same circle or the concentric circle on the confronting surface thereof; or alternatively both the magnetic material segments and the permanent magnet segments are disposed on the same circle or the concentric circle.

Magnetic field generating device for MRI

A magnetic field generating device for nuclear magnetic resonance-computerized tomography of the type wherein permanent magnet assemblies of a pair opposing mutually to define an air gap therebetween are magnetically coupled together by yoke means to create a magnetic field within the air gap is provided, which is characterized in that each permanent magnet assembly comprises a flat plate-like central permanent magnet and peripheral permanent magnets arranged around the central permanent magnet and inclined toward the inside of the air gap, the magnetic pole surface of each permanent magnet assembly forms a curved concave face with respect to the air gap, and each permanent magnet is magnetized in the direction perpendicular to the corresponding magnetic pole surface, whereby the leakage flux is reduced and the magnetic efficiency is enhanced, thus, reduction of the device dimension and weight can be achieved.

Magnetic field generating device for NMR-CT

A magnetic field generating device for a nuclear magnetic resonance-computerized tomography comprising a pair of permanent magnets magnetized in the same direction with different-polarity poles opposing mutually to define an air gap, whose maximum energy product, (BH).sub.max, is not less than 30 MGOe (240 KJ/m.sup.3), on each of the opposing faces of the permanent magnets a magnetic pole segment being provided which has an annular projection and, as occasion demands, at least one central convex projection inside the annular projection, and the permanent magnets being coupled magnetically by a yoke to generate a magnetic field within the air gap. The present device is able to create a uniform and stable magnetic field, in spite of its small-sized body.

Growing community of inventors

Mishima, Japan

Youichi Ohnishi