JP2007251012A - Magnetic shield equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide magnetic shield equipment having improved efficiency to terrestrial magnetism. <P>SOLUTION: In the magnetic shield equipment for demarcating a magnetic shield space by arranging a magnetic laminate 1 by overlapping a Co group amorphous alloy thin plate, the butt of the adjacent magnetic laminate 1 is blocked by a lamination crosslinking member 14 of the Co group amorphous alloy thin plate without any seams in a long widthwise direction along the extension direction of the butt. In the magnetic laminate 1, knitted magnetic shield materials are overlapped for performing the plain weaving of the Co group amorphous alloy ribbon shaped material. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a biomagnetic field measurement apparatus that measures a weak magnetic field generated from a living body using, for example, a SQUID or the like, various physics and chemistry instruments, or a magnetic shield apparatus used in a semiconductor processing apparatus that uses an electron beam. .

  In a biomagnetic field measuring apparatus that measures a weak magnetic field generated from the heart or brain by SQUID or the like, the detected magnetic field strength is as weak as about 10 minus 10 Tesla (T), and therefore, about 30 micro Tesla (μT). Geomagnetism is a major obstacle. For this reason, a magnetic shield device that attenuates the geomagnetism by at least 50 dB is required. As a magnetic shield member required for this, a high-permeability permalloy plate or silicon steel plate, which is an Fe-Ni alloy, or a soft magnetic alloy thin film having an ultrafine crystal structure with a crystal grain size of 100 nm or less and Magnetic laminated members in which polymer sheets are stacked and bonded have been proposed.

As an example of the basic structure of the magnetic shield device, a box-type structural frame made of aluminum or the like is used as a magnetic shield member with a high-permeability permalloy plate or silicon steel plate made of Fe-Ni alloy as a wall material or flooring material. In some cases, the magnetic shield space is defined by fixing with bolts or the like (see, for example, Patent Document 1). In addition, instead of a permalloy plate, it is also proposed to use a magnetic shield sheet material in which a thin film of a soft magnetic alloy having an ultrafine crystal structure having a crystal grain size of 100 nm or less and a polymer sheet are stacked and bonded as a magnetic shield member. (For example, refer to Patent Document 2).
Japanese Patent Laid-Open No. 5-183288 (2nd page, FIG. 1) JP 2000-077780 A (Page 3, FIG. 6)

  The magnetic shield device disclosed in Patent Document 1 uses a high permeability permalloy plate as a magnetic shield member, and has a structure surrounding a space to be magnetically shielded. In this case, the permalloy plate needs to have a thickness of about 1 mm, and parts processing such as cutting and bending is performed in accordance with the assembly structure of the magnetic shield device. However, although the permalloy plate does not affect the mechanical strength due to the external force applied during component processing, it has a drawback that the magnetic properties are extremely deteriorated. In addition, the magnetic properties of the permalloy plate are greatly reduced even when an external force such as an earthquake is applied to the magnetic shield device after installation. In addition, a magnetic shield device using a permalloy plate requires a permalloy thickness of about 1 mm or more for each layer, and even a magnetic shield device having a size of about 2 m × 2 m × 2 m reaches a weight of several hundred kg or more. End up. Furthermore, in order to increase the magnetic shield rate, the single layer structure of the permalloy plate is not sufficient, and a multilayer structure is necessary. In this case, the magnetic shield device becomes a weight of 1 ton or more, and the magnetic shield There is a problem that the movement of the apparatus is difficult. On the other hand, in the magnetic shield device disclosed in Patent Document 2, instead of a permalloy plate as a magnetic shield member, a thin film of a soft magnetic alloy having an ultrafine crystal structure with a crystal grain size of 100 nm or less and a polymer sheet are stacked. A bonded magnetic shield sheet material is used. In this case, unlike the permalloy plate, the magnetic properties are not deteriorated even if a slight external force is applied, but the alloy portion having an ultrafine crystal structure is weak in mechanical strength and easily breaks due to the external force. In the event of an earthquake or the like, mechanical failure may occur in the alloy part having an ultrafine crystal structure inside even though it does not appear to have an influence on the appearance.

  Therefore, an object of the present invention is to provide a magnetic shield device that solves the above-mentioned problems, is strong against external force and is lightweight, and can be used to effectively shield geomagnetism of about 30 microtesla (μT). That is. In particular, it is an object of the present invention to provide a magnetic shield device capable of attenuating a geomagnetism of about 30 microtesla (μT) by a minimum of 50 dB.

  As a technical means for achieving the above-mentioned object, a magnetic shield space is defined by arranging a magnetic laminate formed by laminating Co-based amorphous alloy thin plates, and a butt portion of an adjacent magnetic laminate is used as the butt. A magnetic shield device is proposed that is covered with a laminated bridge member made of a Co-based amorphous alloy thin plate that is long along the extending direction of the portion and seamless in the width direction.

  As the magnetic laminate, a knitted magnetic shield material obtained by plain weaving a Co-based amorphous alloy ribbon-shaped material is overlapped and is preferably lapped. Specifically, for example, one ribbon-shaped Co-based amorphous alloy substrate is used as a warp, and the other ribbon-shaped Co-based amorphous alloy substrate is used as a weft. After laminating a plurality of plain knitted magnetic shield materials so that there is no magnetic layer, and applying heat in the laminating direction to a maximum temperature of 300 ° C. to 480 ° C. Each is covered with a resin sheet, and the two opposite edges are extended from the edge of the magnetic layered body, and the sheets of the extension part are joined together. The magnetic laminate is sandwiched from both sides by the resin sheet by this lapping process. In this case, at least one of the ribbon-shaped Co-based amorphous alloy base materials used as warp or weft may be a stack of a plurality of Co-based amorphous alloy ribbon materials.

  As the magnetic laminate, it is possible to use a magnetic laminate in which a plurality of Co-based amorphous alloy ribbon-shaped materials are abutted in the ribbon width direction and spread in a flat shape, and these are stacked in the plate thickness direction. . Those that have been lapped are preferred.

  The Co-based amorphous alloy base material preferably has a coercive force (Hc) of 0.4 A / m or less, a saturation magnetostriction constant of 10 minus 6 or less, and a maximum DC magnetic permeability of 10,000 or more. .

  The alloy component of the Co-based amorphous alloy has a composition formula: (Co1-xy-zFexMnyNiz) 100-ab-cMaSibBc [where M is Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W , Cu, Ag, Au, Y, and at least one element selected from rare earth elements], and x is 0 to 0.1, y is 0 to 0.1, and z is 0 to 0. It is preferable that 0.2, a is 0 to 6, b is 8 to 18, c is 7 to 18, and (b + c) is 18 to 30.

  In some cases, the laminated bridge member of the Co-based amorphous alloy thin plate is preferably lined with a nonmagnetic reinforcing plate. The nonmagnetic reinforcing plate increases the mechanical strength of the laminated bridge member, and an Al thin plate, a stainless thin plate, or the like can be used.

  The nonmagnetic reinforcing plate is usually disposed on the opposite side of the butt portion through a laminated bridge member made of a Co-based amorphous alloy thin plate.

  In order to enhance the magnetic shielding effect, it is preferable to arrange the magnetic laminate so as to have at least a double structure in the inner and outer surface directions.

  It is advantageous that the Co-based amorphous alloy sheet is subjected to a heat treatment at a maximum temperature of 300 ° C. to 480 ° C.

  As the sheet used for the lapping process, a PET (polyethylene terephthalate) resin sheet or the like may be used, or a sheet obtained by mixing metal flakes with a resin or a thin film metal sheet may be used. As a method of joining the sheets of the extending portion, various means such as joining with an adhesive or heat pressing may be employed.

  In order to efficiently perform the heat treatment of the Co-based amorphous alloy thin plate, it is preferable that the tray containing the magnetic laminate is multi-staged and placed in a heat treatment furnace.

  In the magnetic shield device of the present invention, an amorphous alloy having no crystal grain boundary is used as a base material. Therefore, unlike the case of using an alloy having an ultrafine crystal structure, the alloy can be applied even if some external force is applied. Because of its high mechanical strength, there is almost no breakage. Even in the event of an earthquake or the like, mechanical fracture hardly occurs in the amorphous alloy portion of the base material.

  The magnetic shield device made according to the present invention is excellent in mechanical strength, lightweight, excellent in magnetic characteristics, and can attenuate geomagnetism of about 30 microtesla (μT) by at least 50 dB. Even when an external force such as an earthquake is applied, the magnetic properties of the Co-based amorphous alloy base material hardly deteriorate. In particular, since a laminated bridge member made of a Co-based amorphous alloy thin plate covering the butt portion of the adjacent magnetic laminate is disposed, the magnetic resistance at the butt portion of the magnetic laminate is small and the magnetic shielding effect is great. In accordance with the present invention, a magnetic laminate panel member is created in advance, and this is stretched around a structural frame and combined, and then the laminated bridge member is arranged to simplify the manufacturing process of the magnetic shield device. The assembly time can be shortened.

  One of the features of the present invention is that a Co-based amorphous alloy is used as a magnetic material for shielding geomagnetism of about 30 microtesla (μT). Magnetic materials for shielding magnetism include silicon steel plate, permalloy, Fe-based amorphous alloy, Co-based amorphous alloy, and soft magnetic Fe-based alloy having an ultrafine crystal structure with a crystal grain size of 100 nm or less There are soft magnetic Co-based alloys with ultrafine crystal structures with crystal grain sizes of 100 nm or less, but silicon steel plates and Fe-based amorphous alloys are used to shield low-frequency magnetism or static magnetism of 1 kHz or less. However, since the magnetic permeability is too small, it is necessary to use a thick plate, which makes the weight too large and is not practical.

  The magnetic permeability of soft magnetic alloys with an ultrafine crystal structure with crystal grains of 100 nm or less is considerably larger than that of silicon steel plates or Fe-based amorphous alloys, and shields low-frequency magnetism or static magnetism of 1 kHz or less. Although it is a preferable material in terms of magnetic properties, the mechanical strength of the alloy part with an ultrafine crystal structure is compared because it undergoes heat treatment at a temperature close to the crystallization temperature in order to crystallize the amorphous alloy ribbon. It is easily broken by external force. In the event of an earthquake or the like, the alloy portion having an ultrafine crystal structure may break the material even if it appears to have no effect on the appearance.

  Permalloy has a problem that the magnetic characteristics are extremely deteriorated due to an external force applied at the time of machining, and that the magnetic characteristics are greatly deteriorated when an external force due to an earthquake or the like is applied to the magnetic shield device. In order to recover the characteristics of the permalloy plate having deteriorated magnetic characteristics, it is necessary to take measures such as heat treatment again. In addition, a magnetic shield device using a permalloy plate requires a permalloy thickness of about 1 mm or more, and even a magnetic shield device having a size of about 2 m × 2 m × 2 m may reach a weight of 1 ton or more in some cases. There is a problem that it ends up. The present invention is based on the knowledge that a Co-based amorphous alloy is particularly excellent as a magnetic material for shielding geomagnetism of about 30 microtesla (μT).

  As a magnetic laminate used in a large-volume magnetic shield device that uses a magnetocardiograph for checking the health of the heart, a large-area magnetic laminate with a large thickness (for example, 320 μm) is working. Although the ribbon-shaped Co-based amorphous alloy is long (for example, 30,000 m), the ribbon width is about 200 mm at the maximum and the plate thickness is the maximum. Only about 20 μm to 50 μm can be obtained. In order to obtain a magnetic laminate having a large area and a large plate thickness, a large number of ribbons are arranged in the width direction and the end portions in the width direction are joined together to form a large plate, and these thin plates are overlapped in multiple layers. By bonding the layers with a resin or the like, it is possible to obtain a magnetic laminate having a large area and a large plate thickness.

  As another means, for example, if a plain weave is used without any gaps, using a long ribbon spool of a Co-based amorphous alloy that has been cast or heat-treated, the ribbon has a thickness approximately twice that of the ribbon. The knitted magnetic shield material having a wide width as desired and a long length (for example, 30,000 m) is obtained. A dedicated knitting machine based on the same principle as that of a normal cloth weaving machine can efficiently produce a knitted magnetic shield material. Since the elasticity of the Co-based amorphous alloy is greater before heat treatment, it is heat treated as a laminated body on a tray after being knitted magnetic shield material by a special loom (usually 300 ° C. to 480 ° C. for 1 to 2 hours. It is better to heat). After the heat treatment, the magnetic laminate is wrapped (WRAP) with a sheet of resin or the like, and the extended portion of the sheet is subjected to thermocompression bonding. By performing these operations continuously, a long magnetic shield member can be manufactured. When constructing the magnetic shield device, it can be cut and used. By performing the heat treatment, the maximum direct-current permeability of the Co-based amorphous alloy can be further increased, and the magnetic shield performance can be further improved.

  In order to increase the efficiency of the magnetic shield, when weaving plainly, use a plurality of ribbons as one warp, and similarly use a plurality of ribbons as the other weft. By knitting plain so that there is no gap, it is also possible to obtain a knitted magnetic shield member whose plate thickness is about four times or more the ribbon plate thickness. By laminating the knitted magnetic shield material thus created in the plate thickness direction, a magnetic laminate having a plate thickness 10 to 60 times the ribbon plate thickness can be easily obtained. After the heat treatment, resin sheets or the like are respectively disposed on both surfaces of the magnetic laminate directly or indirectly via an Al plate, for example, extending from the edges of the laminate at at least two opposite edges in the width direction, The sheets of the extension part are joined partially or entirely to form a magnetic shield member. Such a magnetic shield member has sufficient magnetic shielding characteristics when used for a wall material of a magnetic shield room.

  As the magnetic laminate, it is preferable that the Co-based amorphous alloy ribbon material has a multilayer structure of 15 layers or more in order to obtain sufficient magnetic shield characteristics. Compared with a permalloy magnetic shield plate, the magnetic laminate of the present invention formed by superimposing Co-based amorphous alloy ribbons can exhibit a magnetic shield effect higher than that of permalloy while being lightweight. The same situation applies when a magnetic shield member incorporating a magnetic laminate for defining a magnetic shield space is arranged in multiple layers as a wall material to maximize the magnetic shield effect. By combining a lightweight metal material such as aluminum as a framework member, the entire magnetic shield device can be reduced in weight.

  When multiple layers of magnetic laminates that define the magnetic shield space are arranged as wall materials, for example, foamed polystyrene is applied to the gaps between these walls to enhance the magnetic shield effect and increase the mechanical strength of the magnetic shield room. Furthermore, the air conditioning efficiency of the magnetic shield room interior space can be increased. By setting the total number of laminated Co-based amorphous alloy ribbon materials arranged in the wall material to 30 or more, the geomagnetism of about 30 microtesla (μT) can be easily attenuated by at least 50 dB. For magnetic shield devices required for magnetoencephalographs and other devices that require higher shield efficiency (performance), increase the number of layers to more than 30 layers, or use multiple shield arrangements of three or more layers. Thus, it is possible to obtain the necessary shield efficiency (performance), and such a method is possible by applying the present technology.

Hereinafter, embodiments of the present invention will be further described with reference to the drawings.
FIG. 1 is a partial perspective schematic view of a magnetic shield device of the present invention, in which a laminated bridge member 14 is arranged so as to cover a gap 13 between two magnetic shield members 12 having a magnetic laminate 20 attached on the front and back. is there. The magnetic laminated body 20 and the laminated bridge member 14 are made of heat-treated Co-based amorphous alloy thin plates. Such magnetic shield members are pasted as walls, floors, and ceiling materials to form a magnetic shield space. Laminated bridge members 14 including the corner portions are arranged at the joints of these magnetic shield members to reduce the magnetic resistance of the gap portions.

  By fixing these magnetic shield members to a lightweight metal frame member made of aluminum to form a magnetic shield room panel member, the assembly process of a magnetic shield device such as a magnetic shield room can be simplified. As such a panel, as shown in FIG. 1, the magnetic laminate is arranged in double in the wall thickness direction and, for example, a foamed polystyrene plate is applied between them, so that the panel hardly increases in weight. It is possible to increase the mechanical strength and the heat insulation effect. The gap between the magnetic laminates to be arranged is preferably 10 mm to 200 mm, so that the efficiency of the magnetic shield is enhanced by combining the two magnetic laminates.

  It is preferable that the magnetic shield space is defined by these panels and the inner peripheral wall is finished with a decorative material. A magnetic shield room utilizing the present invention can be formed by a simple construction method in which a room skeleton is formed with a framework member made of a light metal material of aluminum like a normal house, and then the magnetic shield member is bonded to the skeleton.

  A magnetocardiograph or magnetoencephalograph is installed in the magnetic shield space of the magnetic shield room formed in this way, the magnetic field generated from the heart or brain is measured using SQUID, and the distribution of current flowing through the heart or brain is used as an image. The health state of the living body can be grasped by means such as capturing. On one side of the magnetic shield device, a door (not shown) used for entering / exiting a person or carrying in medical equipment is provided.

  As the light metal frame member, an aluminum material is suitable, but other light metal materials such as a magnesium material can also be used. It is the same as ordinary construction that weight can be reduced without reducing strength by making the frame member hollow. The light metal frame member increases the overall strength of the magnetic shield device.

  After forming the skeleton of the magnetic shield room with the frame member, the magnetic shield member of the present invention can be bonded to form the inner wall and the outer wall to define the magnetic shield space. Alternatively, a frame member can be used to form a frame of a panel member, which is prepared in advance and a magnetic shield member is bonded to both sides of the panel to form a magnetic shield room. In order to protect the outer surface of the magnetic shield room and provide a clean feeling, it is preferable to arrange the decorative plate as an outer surface finishing material.

  Ribbon-shaped Co-based amorphous alloy base materials generally have a thickness of 8 μm to 80 μm, usually 16 μm to 40 μm, by injecting a melt of Co-based alloy onto the surface of a rapidly rotating cooling roll. Obtained as an amorphous alloy. The width is generally 5 mm to 200 mm. The Co-based amorphous alloy sheet has a magnetic permeability of about 80,000 or more at 1 kHz. The alloy composition is preferably the composition formula: (Co1-xy-zFexMnyNiz) 100-ab-cMaSibBc [where M is Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Cu, Ag. , Au, Y, at least one element selected from rare earth elements], and x is 0 to 0.1, a is 0 to 6, and (b + c) is 18 to 30, y is 0 to 0.2, b is 8 to 18, z is 0 to 0.13, and c is 7 to 18. The Co-based amorphous alloy sheet used in the present invention has no crystal grain boundaries and has a completely amorphous metal structure. The Co-based amorphous alloy base material has a coercive force (Hc) of 0.001 Oe or less, a magnetostriction of 10 minus 6 or less, and a DC maximum permeability of 10,000 or more. A shield member is obtained.

  The wall of the magnetic shield room using the present invention is provided with a through hole or a vent hole, and can take in air from the outside or pass cables for electronic devices. The through hole can also be formed by inserting a tube formed by rolling the magnetic shield member of the present invention. In this way, air can be taken in and cables can be passed without deteriorating the magnetic shield rate.

  A magnetic shield member using a Co-based amorphous alloy instead of permalloy that has been used in the prior art generally depends on the laminated structure, but generally has a magnetic permeability of 80 μm to 300 μm and a high magnetic permeability. Become. This magnetic shield member is lighter than Permalloy, has a high magnetic shield rate, and does not deteriorate in magnetic properties or mechanical strength even when an external force is applied. Even if you encounter a movement of the magnetic shield device or an earthquake, it is safe. It is easy to bend and cut, and can be handled like wallpaper.

In the prior art, a magnetic shield space is defined using a permalloy plate as a main member of the wall structure. However, in the present invention, a light metal material such as aluminum is used as a frame member of the magnetic shield device, and the magnetic shield is used. If the magnetic shield member of the present invention is used after defining the space, a magnetic shield room can be easily constructed.
Since the Co-based amorphous alloy ribbon is multi-layered, it is possible to realize a magnetic shield rate equal to or higher than that of a permalloy having a thickness of about 1 mm. The number of Co-based amorphous alloy ribbons to be stacked is preferably 10 or more, and more preferably a multilayer structure having 20 to 50 layers.

  The magnetic shield room using the permalloy of the prior art as the magnetic shield plate is heavy and difficult to assemble and move, but the magnetic shield room using the present invention is lightweight and adapts to changing the installation location in the hospital it can. Further, it is strong against external forces in terms of magnetic characteristics and mechanical strength, and its manufacturing method can be simplified. The installation of the through-hole connecting the equipment installed inside and the outside or the installation of the door are also easy to cut, so the construction is easy. Since it is easy to assemble the device using bolts, adhesives, etc., the industrial utility is high. Since the magnetic shield device of the present invention is lightweight, the floor strength is not so much required, and the option of selecting the structure and material is expanded.

The partial perspective schematic diagram of the magnetic shielding apparatus of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Magnetic laminated body, 2 ... Buffer material, 12 ... Magnetic shielding member, 13 ... Gap | interval, 14 ... Laminated bridge member.

Claims (9)

In a magnetic shield device that demarcates a magnetic shield space by arranging a magnetic laminate formed by stacking Co-based amorphous alloy thin plates, abutting portions of adjacent magnetic laminates are elongated along the extending direction of the butting portions. A magnetic shield device characterized in that it is closed with a laminated bridge member made of a thin Co-based amorphous alloy sheet that is seamless in the width direction. 2. The magnetic shield device according to claim 1, wherein the magnetic laminated body is formed by superposing knitted magnetic shield materials obtained by plain weaving of a Co-based amorphous alloy ribbon-shaped material and lapping. The magnetic laminate is formed by laminating a plurality of Co-based amorphous alloy ribbon-shaped materials in the ribbon width direction and laying them flat, and stacking them in the plate thickness direction, and lapping is performed. The magnetic shield device according to claim 1. 2. The Co-based amorphous alloy base material according to claim 1, wherein the coercive force (Hc) is 0.4 A / m or less, the saturation magnetostriction constant is 10 −6 or less, and the maximum DC magnetic permeability is 10,000 or more. Magnetic shield device. The alloy component of the Co-based amorphous alloy has a composition formula: (Co1-xy-zFexMnyNiz) 100-ab-cMaSibBc [where M is Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W , Cu, Ag, Au, Y, and at least one element selected from rare earth elements], and x is 0 to 0.1, y is 0 to 0.1, and z is 0 to 0. The magnetic shield device according to claim 1, wherein 0.2, a is 0 to 6, b is 8 to 18, c is 7 to 18, and (b + c) is 18 to 30. A magnetic shield device, wherein the laminated bridge member of the Co-based amorphous alloy thin plate is lined with a nonmagnetic reinforcing plate. The magnetic shield device according to claim 6, wherein the nonmagnetic reinforcing plate is disposed on a side opposite to the butt portion through a laminated bridge member made of a Co-based amorphous alloy thin plate. A magnetic shield device, wherein the magnetic laminate is disposed so as to have at least a double structure in the inner and outer surface directions. The magnetic shield device according to claim 1, wherein the Co-based amorphous alloy thin plate is subjected to a heat treatment at a maximum temperature of 300 ° C to 480 ° C.

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