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The magnetic shield device including a plurality of concentrically arranged open-ended cylinders having a magnetic shaking applied thereto. A rectangular magnetic ribbon is fixed on the innermost cylinder such that a longitudinal direction of the ribbon is in parallel with or substantially in parall

The magnetic shield device including a plurality of concentrically arranged open-ended cylinders having a magnetic shaking applied thereto. A rectangular magnetic ribbon is fixed on the innermost cylinder such that a longitudinal direction of the ribbon is in parallel with or substantially in parallel with a circumferential direction of the cylinder to obtain a large magnetic shielding enhancement on a transverse direction, and a coil is wound around the innermost cylinder for supplying a magnetic shaking current. A rectangular magnetic ribbon is fixed on at least one cylinder except for the innermost one such that a longitudinal direction of the ribbon is in parallel with or substantially in parallel with an axial direction of the cylinder to obtain a large magnetic shielding enhancement on the axial direction, and a coil is wound around the cylinder for supplying a magnetic shaking current. A leakage of the magnetic shaking fields can be minimized and a high magnetic shielding enhancement on both the axial and circumferential directions can be attained. At least one cylinder is made of a magnetic material, and axial length and diameter of cylinders are suitably adjusted to attain a uniformity of a leakage magnetic field within the cylinder can be improved while a sufficiently high shielding factor is remained.

대표청구항 ▼

[ What is claimed is:] [1.]1. An open-ended cylindrical magnetic shield device including at least two open-ended cylinders which are arranged concentrically, a magnetic shaking being applied to each of said cylinders wherein;a ribbon made of a magnetic material having a rectangular hysteresis loop i

[ What is claimed is:] [1.]1. An open-ended cylindrical magnetic shield device including at least two open-ended cylinders which are arranged concentrically, a magnetic shaking being applied to each of said cylinders wherein;a ribbon made of a magnetic material having a rectangular hysteresis loop is fixed on an innermost cylinder such that a longitudinal direction of the ribbon is in parallel with or substantially in parallel with a circumferential direction of the cylinder to obtain a large magnetic shielding enhancement on a transverse direction;a coil is wound around the innermost cylinder, a magnetic shaking current being supplied to said coil;a ribbon made of a magnetic material having a rectangular hysteresis loop is fixed on at least one cylinder other than said innermost cylinder such that a longitudinal direction of the ribbon is in parallel with or substantially in parallel with an axial direction of the cylinder such that a large magnetic shielding enhancement is obtained on the axial direction; anda coil is wound around said at least one cylinder, a magnetic shaking current being supplied to said at least one cylinder. [11.]11. An open-ended cylindrical magnetic shield device comprising a single open-ended cylinder made of a magnetic material, said cylinder being constructed to satisfy the following equation: rein L is an axial length, D is a diameter and t is a thickness of said cylinder, .mu. is a relative permeability of the magnetic material of the cylinder, and C is a constant within a range from 0.5 to 1.2.12. The open-ended cylindrical magnetic shield device according to claim 11, wherein the constant C is set to a value within a range from 0.75 to 1.0. [13.]13. An open-ended cylindrical magnetic shield device including a plurality of open-ended cylinders made of magnetic materials and arranged concentrically, wherein said cylinders are divided into first and second groups such that a sign of axial and/or radial gradients of magnetic fields within one or more cylinders belonging to the first group is opposite to a sign of axial and/or radial gradients of magnetic fields within one or more cylinders belonging to the second group, and a ratio between length L and diameter D of these cylinders are set such that a magnitude of a gradient of composed magnetic fields in the first group becomes substantially identical with a magnitude of a gradient of composed magnetic fields in the second group.14. The open-ended cylindrical magnetic shield device according to claim 13, wherein first and second cylinders arranged concentrically are made of a same magnetic material to have a same thickness.