JP2002374089A - Magnetic laminate for magnetic shield and magnetic shield device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lightweight magnetic shield having high performance magnetic shield characteristics. SOLUTION: A magnetic body being employed as a material has a sheet-like shape and the thickness of one sheet 11a is 10-200 μm. Two or more sheets constitute the laminate for a magnetic shield provided with a nonmagnetic supporting plate 11b on at least one side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic shield, and more particularly, to a magnetic shield having a hollow structure.

[0002]

2. Description of the Related Art FIG. 9 or FIG.
Has a rectangular cross-sectional structure 140 and a ring-shaped cross-sectional structure 150 as shown in FIG.
Generally, a structure in which the wall of the magnetic material constituting the shield is doubled or tripled or a structure in which the thickness of the magnetic material of the wall is changed is used.

[0003]

However, in the prior art, in order to obtain sufficient shielding characteristics, the thickness of the magnetic body is increased even if the magnetic body on the wall has a double or more multiple structure. I had to. This is because the magnetic flux control in the space tends to be insufficient depending on the basic structure of the conventional magnetic shield. For example, as a general principle, at the interface between a magnetic material having a high magnetic permeability and vacuum (air), the magnetic flux density is continuous in the direction perpendicular to the interface with respect to the direction of the magnetic flux in the vacuum, and in the direction parallel to the interface. The magnetic field becomes continuous. Here, the relative permeability of the magnetic material is μ,
Assuming that the magnetic flux density is B, the magnetic field H is given by H = B / μ. Therefore, as the relative permeability μ increases, the parallel component of the spatial magnetic field near the interface decreases.

When the magnetic flux density in the space increases, the magnetic field in the magnetic body also increases, so that the magnetic body approaches saturation. At this time, since the relative magnetic permeability of the magnetic material decreases, the shield characteristics deteriorate. In order to avoid this effect, it is necessary to increase the saturation magnetic flux density of the magnetic material or to reduce the density by increasing the thickness of the magnetic material. In the prior art, in order to improve the shield ratio, permalloy (NiF) having a large relative magnetic permeability is used.
e alloy) is often used. For Permalloy,
Since the saturation magnetic flux density was relatively small, it was necessary to increase the thickness of the magnetic material. In addition, the conventional technology does not have the technology to control the magnetic flux component in the direction perpendicular to the interface between the magnetic material and the vacuum, so the only way to shield the magnetic flux of the vertical component is to increase the refractive index at the interface of the magnetic flux lines. Met.
In this method, since the refractive index is proportional to the relative magnetic permeability, it is necessary to keep the thickness of the magnetic material sufficiently large to avoid deterioration of the relative magnetic permeability.

As a technique for avoiding magnetic saturation of a magnetic material for shielding, a technique of providing a tapered shape at a bent portion as disclosed in Japanese Patent Application Laid-Open No. 55-82278, or a double magnetic path having a tapered shape. For example, there is a technique of providing a magnetic body for performing the operation. However, the prior art disclosed therein is a technique for avoiding saturation of the magnetic flux collected for performing the shielding, and it is not possible to efficiently control the magnetic flux of the external magnetic field with respect to the entire apparatus for performing the magnetic shielding. .

After all, these prior arts have a problem that the thickness of the magnetic body must be increased, so that the shield wall constituting the magnetic shield becomes heavy.
This problem can be solved by, for example, weakening the structural strength of the wall surface to reduce the overall weight when the volume of the space for the magnetic shield is small. However, when the shielding space is large, the shield wall itself has a large area, and the structure that supports the shield wall is large and has sufficient strength as the own weight increases. In this situation, it was impossible to reduce the weight of the structure by reducing the proportion of the magnetic material in the conventional shield structure.

An object of the present invention is to solve the above problems and to provide a magnetic laminate for a magnetic shield and a magnetic shield device having a lightweight and high-performance shield characteristic. It is another object of the present invention to provide a magnetic laminate for a magnetic shield and a magnetic shield device in which assembling of a magnetic shield is simplified and workability is greatly improved.

[0008]

According to a first aspect of the present invention, a magnetic material used as a material has a sheet shape, the thickness of one sheet is not less than 10 μm and not more than 200 μm, and A magnetic laminate for a magnetic shield, comprising a laminate of the above sheets and having a support plate made of a non-magnetic material on at least one surface.

The above-mentioned one sheet can be formed by arranging narrow magnetic members in parallel with no gap. In order to arrange without gaps, it is necessary to partially overlap adjacent narrow magnetic bodies,
Or you may match. The latter is preferred because the magnetic sheet is less likely to be damaged or distorted when the magnetic laminate for a magnetic shield is used in a portion subjected to a load of a device placed in a magnetically shielded space.

[0010] The magnetic laminate for a magnetic shield of the present invention may include a sheet in which the direction in which narrow magnetic bodies are arranged is different from other sheets. The magnetic sheet has directionality, and the magnetic resistance is small when the longitudinal direction of the narrow magnetic body (thin body) and the direction of the magnetic field are parallel to each other, and large when the magnetic sheet is perpendicular to the magnetic field. In the space where the device is installed, there are various AC magnetic fields generated from surrounding electronic devices and power lines in addition to the geomagnetism. In order to shield all these magnetic fields, it is desirable that the magnetic laminate for magnetic shielding has no directionality. Therefore, it is preferable to form the magnetic laminate for magnetic shield by laminating the sheets while changing the longitudinal direction of the thin body.

In the narrow magnetic body, fine crystal grains having a particle diameter of 500 nm or less containing iron as a main component are at least 50% of the structure.
It is preferable to be made of an alloy material occupying the above and be formed in a sheet or tape shape. This magnetic material has excellent magnetic properties, but the sheet is formed from 5 layers to 15 layers to prevent magnetic saturation.
It is preferable to laminate about layers.

[0012] A second invention of the present application is a magnetic shield device characterized in that a magnetic path is formed by the magnetic laminate for magnetic shield and a magnetic shield of an internal space is performed.

In this magnetic shield device, the magnetic laminate for magnetic shield described above can be used as a component of a floor surface that receives a load of the device. When a magnetic material is subjected to strain, its magnetic characteristics may be degraded. The magnetic sheet made of fine crystal grains of the present invention is less susceptible to stress and strain as compared with a conventional NiFe alloy shield material, and thus is suitable as a floor material for a shield device. However, since the thickness of the magnetic material is thin, the sheet itself may be broken when subjected to a local shear stress. Therefore, the magnetic laminate for a magnetic shield of the first invention used in the present invention receives at least a load. Since the support plate is provided on the side surface, breakage of the magnetic body can be avoided. The support plate is formed of a non-magnetic material because it does not affect the magnetic path. Rigidity is required for the non-magnetic material, and aluminum alloy, stainless steel, resin such as polycarbonate, wood, and the like can be used.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention can provide a more effectively shielded space by combining a magnetic laminate and a magnetic shield. As shown in FIG. 1, when the band-shaped projecting second magnetic members 72 and 73 are arranged on the surface of the first plate-like magnetic member arranged in parallel and opposed to each other, the space to be magnetically shielded can be reduced. The magnetic flux lines are controlled as shown in FIG. A magnetic shield is configured by combining a first plate-shaped magnetic body 71 formed by projecting a second magnetic body with the magnetic laminated body 11. Arrows 1 and 10 represent external magnetic fields. First
The flat magnetic body 71 is composed of a side wall and a top plate. The external magnetic field 1 directed to the side surface is guided to the second magnetic body 72 and the first plate-shaped magnetic body 71 and is shielded from the inside of the magnetic shield. On the other hand, the external magnetic field 10 heading toward the bottom surface 11 is shielded by the magnetic laminate 11 constituting the bottom surface. When the magnetic laminate 11 is not disposed on the bottom surface, the external magnetic field 10 incident from obliquely below enters the internal space as shown by the broken line and exerts an influence of the magnetic field on the device 12.

In the structure of FIG. 1, when the cross-sectional area of the space to be shielded increases, it is necessary to provide a magnetic shield with higher efficiency. In the configuration of FIG. 2, the protruding second magnetic body 72 is disposed on both surfaces of the first magnetic body 71, so that the shielding efficiency near the center of the wall surface can be improved. That is, the second magnetic material is the first magnetic material.
Characterized in that they are arranged in a protruding shape on both sides of the surface of the magnetic body. In particular, a high effect is exhibited when all the three-dimensional magnetic flux direction components are shielded from the installed magnetic shield wall so that the geomagnetism has a dip component. Even if a part of the magnetic fields 80 and 15 having components oblique to the shield wall surface leaks from the magnetic laminate 11 to the internal space, the leakage occurs near the corner of the magnetic laminate 11 so that the leakage magnetic field 82 It is immediately sucked by the protruding second magnetic body 73b provided inside. As described above, the magnetic flux converges on the wall side, and the leakage magnetic field 82 does not affect the device 12 (not shown) installed on the bottom surface sufficiently far from the side wall.

FIG. 3 is a sectional view illustrating another embodiment of the magnetic panel of the present invention. (A) of the figure is a comparative example, (b) is an embodiment. (A) The comparative example illustrates the relationship between the magnetic shield 211 and another device 212 installed near the magnetic shield 211. The other device 212 has a magnetic field generating means 213 inside, and the magnetic field 210 leaks outside. The outer periphery of the magnetic shield 211 is surrounded by a soft magnetic material to magnetically shield the inside. However, there is a problem that the leakage magnetic field 210 enters the magnetic shield 211 depending on the incident angle of the magnetic flux to the magnetic shield 211. Therefore, as shown in FIG. 4B, the magnetic field 214 is concentrated on both ends of the magnetic panel 214 by disposing the magnetic panel 214 according to the present invention between the magnetic shield 211 and another device 212 like a partition plate. In addition, it is possible to prevent the strong leakage magnetic field 210 from being incident on the magnetic shield 211, and to perform a more efficient magnetic shield. Note that, instead of the magnetic panel 214 in which the magnetic laminate is combined with an aluminum plate, a partition wall or a partition to which only the magnetic laminate is adhered is arranged to absorb the leakage magnetic field 210 and shield the magnetic shield 211. Good. Also,
In this embodiment, one magnetic panel is arranged so that its surface is substantially parallel to the leakage magnetic field.However, when the direction of the external magnetic field is not uniform, or when there are a plurality of other devices that generate the leakage magnetic field, A plurality of magnetic panels may be arranged around the magnetic shield 211 in different directions so as to absorb the leakage magnetic field.

Further, according to the present invention, in each of the above-described magnetic materials for a magnetic shield, the magnetic material used as a material has a sheet shape, and the thickness of one sheet is 10 μm.
It is not less than 200 μm. In the configuration using the sheet-shaped magnetic material, the magnetic flux in the space can be collected efficiently, so that a magnetic material having a smaller thickness than that of a conventional magnetic shield can be used. The advantage of using a thin magnetic material is that the structural weight of the magnetic shield can be reduced, and the assembly and workability of the shield device can be improved. For example, in the case of a shield using a rolled thin plate (thickness: 0.5 to 1 mm) such as soft iron or a NiFe alloy, the limit is to form a shield wall of 350 × 350 mm to 500 × 500 mm for a weight of 1 kg. However, a 2 × 2 m shield wall can be formed with a 200 μm sheet, and the number of parts of the shield wall can be greatly reduced. As a characteristic of the shield, the shield ratio of one NiFe plate is about 20 dB,
In the present invention, 10 to 15 d even under the condition of a 10 μm sheet.
B, and by setting this to 200 μm, a shielding ratio of 20 dB or more can be obtained.

The present invention also relates to any of the above magnetic materials for a magnetic shield, wherein the sheet-shaped magnetic material has a sheet thickness of 10 μm or more and 30 μm or less.
It is characterized by comprising a laminate of at least two sheets. In the case of a sheet-shaped magnetic material, magnetic anisotropy may occur depending on the direction in the sheet surface depending on the manufacturing method.
In the present invention, the effect of the magnetic anisotropy can be canceled out by using two or more sheet-shaped magnetic materials in an overlapping manner, and a shielding characteristic independent of the direction of the spatial magnetic field for shielding can be obtained. For example, the magnetic properties of the shield wall surface can be isotropically improved by laminating two sheet-shaped magnetic bodies having magnetic anisotropy so that the easy magnetization directions are perpendicular to each other. In addition, since the effect of lamination increases the volume of the magnetic material used for the shield, the effect of keeping the magnetic permeability of the entire magnetic material high is provided. Therefore, the efficiency of the magnetic shield can be improved.

The present invention also relates to any one of the above magnetic materials for a magnetic shield, wherein the magnetic material has a particle diameter of 500
It is characterized in that it is composed of an alloy material in which fine crystal grains of nm or less occupy at least 50% or more of the structure, and has a sheet or tape shape. The fine crystalline material (also referred to as nanocrystalline material) of this iron alloy (Fe alloy) can be obtained by heat-treating an amorphous material at a desired temperature as disclosed in Japanese Patent No. 2625485, for example. In the configuration of this patent, since the magnetic flux in the space can be collected efficiently, it is possible to use a magnetic material having a smaller thickness than a conventional magnetic shield. In order to obtain a thin magnetic material, for example, there is a foil body by rolling or ultra-quenching method. Since the characteristics are liable to be deteriorated, there is a possibility that a problem such as difficulty in handling when constructing the shield wall may occur. Particularly, in the case of a NiFe alloy, the hardness of the material becomes insufficient, and the crystal defects generated by deformation of the sheet due to the weight of the shield wall significantly deteriorate the magnetic characteristics. On the other hand, in a magnetic sheet obtained by heat-treating a foil body formed by rapidly quenching an Fe-based alloy having a high magnetic permeability, the obtained Fe-based alloy has sufficient hardness and causes a reverse magnetostriction effect. Due to the difficulty, it is possible to obtain a sufficiently thin magnetic sheet. In addition, as described in Japanese Patent Application Laid-Open No. 6-112031, it is possible to make it difficult to break down the material due to mechanical deformation and to remarkably reduce shape restrictions on processing. In the magnetic shield of the present invention using the magnetic sheet, the shield wall can be reduced in weight and the influence of stress can be eliminated as much as possible, so that the handling of the material during construction is simple. As described above, according to the present invention, it is possible to provide a magnetic shield that is lightweight and has excellent workability.

The iron alloy (Fe) used for the magnetic material according to the present invention
Alloy) is preferably Fe-Cu-Nb.
-A soft magnetic material having a fine crystal structure (or fine crystal grains) of bccFe of the Si-B type is used. More preferably, a material having an average crystal grain size of the fine crystal grains of 100 nm or less is used.

The magnetic anisotropy of the magnetic laminate for a magnetic shield of the present invention will be described with reference to FIGS. FIG. 4 shows a magnetic sheet 11a formed by arranging narrow magnetic bodies 11aa. Narrow magnetic material has easy magnetization direction He and hard magnetization direction Hd
And To shield magnetic fields with various directions,
As shown in FIG. 5, for example, the magnetic sheets 11a are stacked while the direction of easy magnetization is shifted by 90 °. The magnetic sheets are fixed with adhesive wax. In one example, the thickness is 20μ
By stacking ten magnetic sheets of m, a sheet having a thickness of about 200 μm can be obtained. A nonmagnetic support plate 11b is fixed to at least one side of this sheet to form a magnetic laminate 11 for magnetic shield (FIG. 6). The influence of the stress on the magnetic sheet can be suppressed by the support plate. If the support plates are fixed to both sides of the magnetic sheet, the influence of the stress on the magnetic sheet is further suppressed (FIG. 7).

FIG. 8 shows an example of an embodiment in which the magnetic laminated body 11 is used as a member constituting the bottom surface of a magnetic shield device to receive the load of the device 12. However, the side wall and the top plate of the magnetic shield device are not shown. Here, the magnetic laminated body 11 receives the load of the device 12 on the surface provided with the support plate 11b. The thickness of the support plate 11b depends on its material, the load of the device 12,
It can be determined by the installation area and the like.

[0023]

According to the present invention, a lightweight and high-performance magnetic shield can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of a magnetic shield device.

FIG. 2 is a sectional view of another magnetic shield device.

3A is a cross-sectional view of a magnetic shield device having a conventional structure, and FIG. 3B is a cross-sectional view when the magnetic shield device of the present invention is used upright.

FIG. 4 is an external view of a magnetic sheet used in the present invention.

FIG. 5 is an external view of a magnetic sheet used in the present invention.

FIG. 6 is an external view of a magnetic laminate for a magnetic shield used in the present invention.

FIG. 7 is an external view of a magnetic laminate for a magnetic shield used in the present invention.

FIG. 8 is an external view of a magnetic shield device (side walls and a top plate are not shown) used in the present invention.

FIG. 9 is a sectional view of a magnetic shield having a conventional structure.

FIG. 10 is a sectional view of a magnetic shield having a conventional structure.

[Explanation of symbols]

 1, 10: External magnetic field 2, 71: First flat magnetic body 72, 73: Second magnetic body 11: Magnetic laminate 11a: Magnetic sheet 11aa: Narrow magnetic body 11b: Non-magnetic body Support plate 12 ... Device 82 ... Leakage magnetic field He ... Easy magnetization direction Hd ... Hard magnetization direction

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hirokazu Araki 5200 Sankajiri, Kumagaya-shi, Saitama F-term in the Advanced Electronics Research Laboratory, Hitachi Metals, Ltd. 5E321 BB22 BB53 BB55 GG07

Claims (6)

[Claims] 1. A magnetic material used as a material has a sheet-like shape, a thickness of one sheet is 10 μm or more and 200 μm or less, and is formed of a laminate of two or more sheets. A magnetic laminate for a magnetic shield, comprising a support plate made of a non-magnetic material on a surface on the side of the magnetic shield. 2. The magnetic laminate for a magnetic shield according to claim 1, wherein one sheet has a configuration in which narrow magnetic bodies are arranged in parallel without gaps. 3. The magnetic laminate for a magnetic shield according to claim 1, wherein a direction in which the narrow magnetic bodies are arranged includes a sheet different from other sheets. 4. A sheet or tape-like shape comprising an alloy material in which fine crystal grains having a particle diameter of 500 nm or less and containing iron as a main component occupy at least 50% of the structure. A magnetic laminate for a magnetic shield according to the above item. 5. A magnetic shield device, wherein a magnetic path is formed with the magnetic laminate for magnetic shield according to claim 1, and an internal magnetic shield is performed. 6. A magnetic shield device according to claim 5, wherein the magnetic laminate for a magnetic shield according to any one of claims 1 to 4 is used as a component of a floor surface to receive a load.