JPH07131178A - Magnetic shield room - Google Patents

Abstract

PURPOSE:To contrive to give a high magnetic shielding effect to a magnetic shielding room in a single structure by a method wherein a plurality of hexahedrons consisting of plates, which use a high-magnetic permeability alloy as their material and have a contanst thickness or wider, are formed into a multiple structure at a constant interval or wider between the structures interposing magnetic insulators between the structures. CONSTITUTION:A room 10 is constituted of an external room 12 installed on a floor surface FL and an internal room 16 housed in the interior of this external room 12 via a plurality of insulating materials 14 consisting of timbers or the like a necessary interval apart from the room 12. The rooms 12 and 16 are both one made to combine rectangular plates 20 using a high-magnetic permeability alloy as their material with each other to form a cube. The thickness of the plates 20 is set in a thickness of 2mm or thicker and at the same time, the separation interval between both rooms 12 and 16 is set at an interval of 250 or wider. Thereby, the magnetic field in the center of a space 18 in the room 16 can be set at 1/1000 of an earth magnetism (0.46 oersteds) and a very high magnetic shielding effect is attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetically shielded room, and more particularly to a magnetically shielded room capable of providing an indoor space capable of measuring and detecting magnetism extremely weaker than earth magnetism.

[0002]

2. Description of the Related Art When measuring and detecting a weak magnetic field such as an electroencephalogram or a CT scanner, it is necessary to block external magnetic influences, and a magnetically shielded room is preferably used as a means for this purpose. ing. As a magnetically shielded room, a plate material made of permalloy, which is a high-permeability material, is bent to form two 26-sided bodies of similar shape in which regular octagons are combined. There is proposed a double structure in which the above-mentioned 26-faced body is housed and arranged at a required interval (Japanese Patent Publication No. 2-953). In the magnetically shielded room having this structure, since the corners are set to obtuse angles, it is possible to suppress magnetic retention at the corners, and to achieve a high magnetic shielding effect.

[0003]

In the above-mentioned double-structured magnetically shielded room, since the interior space has a 26-sided shape, the area that can be effectively used is narrower than the entire interior space, and the necessary equipment is required. There is a problem that it is difficult to use and it is difficult to use. Therefore, if the entire shielded room is enlarged in order to secure a sufficiently large space for accommodating the equipment and instruments, problems occur in terms of installation space and material cost. Further, it is pointed out that molding and assembling are complicated, the number of steps is large, and the manufacturing cost is high. Furthermore, 26
Since it is in the shape of a face, there is a problem that it is difficult to use the space around the periphery and it is not possible to effectively use the space at the installation location.

In the magnetically shielded room, a magnetic shielding effect of 40 dB can be achieved with respect to the earth's magnetism (0.46 Oersted), and the weak magnetic field of the above-mentioned brain waves and CT scanners can be measured and detected. Can provide enough space. However, when using a squid (SQUID) that detects weaker magnetism, 60d
The magnetic shielding of B is required, and it is desired to propose a magnetic shield room having a simple structure that can achieve this.

[0005]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the problems inherent in the above-mentioned prior art, and has been proposed in order to solve the problems, and has a magnetic structure of a simple structure having a high magnetic shielding effect. The purpose is to provide a shielded room.

[0006]

In order to overcome the above problems and achieve the intended purpose, a magnetic shield room according to the present invention comprises a plurality of plate materials made of a high magnetic permeability alloy and having a thickness of 2 mm or more. It is characterized in that the hexahedron is formed into a multiple structure with a magnetic insulating material (hereinafter simply referred to as an insulating material) interposed therebetween and a distance of 250 mm or more.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a magnetic shield room according to the present invention will be described below with reference to the accompanying drawings with reference to preferred embodiments.

FIG. 1 is a schematic vertical sectional view of a magnetically shielded room according to an embodiment. The room 10 includes an external chamber 12 installed on a floor FL and a wood or the like inside the external chamber 12. The inner chamber 16 is housed with a plurality of insulating materials 14 separated by a predetermined distance. The outer chamber 12 and the inner chamber 16 each have a similar shape formed in a cubic (hexahedral) shape, and various measuring devices (not shown) are housed in the inner chamber 16. That is, since the internal space 18 of the internal chamber 16 has a cubic shape, almost all the area can be effectively used, and various measuring devices can be accommodated with a margin without enlarging the entire shield room. Is possible. Further, since a useless space that is difficult to use is not generated in the outer periphery, the space in the installation place can be effectively used.

Each of the outer chamber 12 and the inner chamber 16 is formed by combining rectangular plate members 20 made of a high magnetic permeability alloy to form a cube. The high permeability alloy is a soft magnetic material such as Fe-45Ni (PB permalloy), 80Ni-Mo-Fe, 78Ni-Mo-.
Cu-Fe (PC permalloy) or 70Ni-10Cu
-12Mn-Fe (Daido symbol PC-X) is preferably used. Further, the thickness dimension of the plate member 20 is set to 2 mm or more, and the space between the chambers 12 and 16 is set to 250 mm or more. As a result, the central magnetic field of the space 18 in the inner chamber 16 becomes 1 of the geomagnetism (0.46 Oersted)
/ 1000 (60 dB), and an extremely high magnetic shielding effect is achieved. In addition, as the insulating material 14,
Not limited to wood, a non-magnetic material can be preferably used.

Next, the results of experiments on the influence of each element in the magnetically shielded room will be described.

[0011]

[Influence of plate thickness] The outer shape of the outer chamber 12 (vertical, horizontal,
The height) is set to 2400 mm and the external chamber 1
In the magnetically shielded room 10 in which the distance between the inner space 16 and the inner space 16 is set to 200 mm, the plate material 2 of high magnetic permeability alloy is used.
As a first example, PC permalloy having a magnetic permeability μm = 24400 is used as 0, and the plate material 20 has a magnetic permeability μm =
A second example uses 100,000 PC permalloy. Then, in the first example and the second example, each chamber 1
The plate thickness of each plate member 20 in 2, 16 is 1 mm to 2.5 mm.
The central magnetic field of the space 18 in the internal chamber 16 when the temperature changed to was measured. As a result, as shown in FIG. 2, in the magnetic shield room 10 according to the first example, the target value of 3/10000 [Oe] (3 / 100000000T (Tesla), 1/1000 or less of earth magnetism) should be achieved. I couldn't. On the other hand, in the magnetic shield room 10 according to the second example, it was confirmed that the target value was achieved by setting the plate thickness to 2.5 mm. That is, it was found that a high magnetic shielding effect can be achieved by increasing the plate thickness with a material having a high magnetic permeability.

The central magnetic field was also measured when the plate thickness of one chamber was kept constant and the plate thickness of the other chamber was sequentially changed, but there was almost no change in the central magnetic field in this case. . However, it has been found that setting the plate thickness of the inner chamber 16 thicker has a higher magnetic shielding effect than making the plate thickness of the outer chamber 18 thicker.

[0013]

[Influence of the space between the rooms] In the magnetic shield rooms 10 of the first and second examples according to the above-mentioned conditions,
The plate thickness of the plate member 20 of the outer chamber 12 and the inner chamber 16 is 2 mm.
Under the condition, the central magnetic field of the space 18 in the internal chamber 16 was measured when the distance between the external chamber 12 and the internal chamber 16 was changed to 150 mm to 300 mm. As shown in FIG. 3, in the magnetic shield room 10 according to the first example, the target value of 3 / 100000000T (Tesla) could not be achieved. On the other hand, in the magnetic shield room 10 according to the second example, the separation distance is set to 25
It was confirmed that the target value was achieved by setting it to 0 mm. That is, it was found from this measurement result that the central magnetic field was reduced by increasing the distance between the outer chamber 12 and the inner chamber 16.

From the measurement results shown in FIGS. 2 and 3, in the magnetically shielded room 10 having the double structure, the central magnetic field is changed to the geomagnetic field.
The optimum condition for 1/1000 (60 dB) of (0.46 oersted) is a PC with permeability μm = 100000.
Permalloy is used, the plate thickness of the plate member 20 is set to 2 mm, and the distance between the outer chamber 12 and the inner chamber 16 is set to 30 mm.
It is set to 0 mm. As a result, it is possible to provide a small magnetically shielded room 10 that exhibits a high magnetic shielding effect. Since the magnetic shielding effect is further improved by using a material having high magnetic permeability, magnetic permeability μm =
By configuring the magnetic shield room 10 by combining PC-X of 336000 and PC permalloy, the separation distance between the outer chamber 12 and the inner chamber 16 is shortened without reducing the magnetic shielding effect, and the entire room is further improved. It is possible to reduce the size.

[0015]

[Influence of joint between plates] Plates 2 to be connected when the magnetic shield room 10 is assembled
With respect to the distance of the magnetic field leaking inward through the gap inevitably generated at the joint of 0 and 20, PC Permalloy having a permeability of μm = 100000 is used as the plate material 20 and the gap thickness is set to 1 mm. The measurement was performed when the length was changed. As a result, it was found that the leakage magnetic field distance became longer as the gap length became longer as shown below.

[0016]

Next, in order to prevent the leakage magnetic field from the above-mentioned gap, as shown in FIG.
The same material and the same thickness on the outside of the 20th joint
Attach the cover plate 22 (1 mm) and set the gap length to 2
With the length set to mm, the plate length L of the cover plate 22 is 0 m.
m, 4 mm, 11.4 mm. A gap of 0.2 mm is inevitably formed between the cover plate 22 and each of the plate members 20, 20. As a result, as shown in FIG. 5, it was found that the leakage magnetic field distance can be set to 1 mm or less by setting the plate length of the cover plate 22 to 11.4 mm. That is, in order to reliably prevent the stray magnetic field from the gap that is inevitably generated at the joint between the plate members 20 and 20, a cover plate 22 having a plate length set to about 6 times the length of the gap is arranged outside the joint. Installation is recommended.

[0018]

[Another Embodiment] FIG. 6 shows a magnetic shield room according to another embodiment of the present invention.
Is configured as a triple structure. That is, the intermediate chamber 24 is provided between the outer chamber 12 and the inner chamber 16 with a plurality of insulating members 14 interposed between the chambers 12 and 16 with a predetermined distance therebetween. The outer chamber 12, the inner chamber 16 and the intermediate chamber 24 in this other embodiment are formed into a cube by combining the rectangular plate members 20 made of the above-mentioned high magnetic permeability alloy. Then, the thickness of each plate member 20 is set to 2 mm or more, and the spacing between the chambers 12, 24 and 16 is set to 250 mm or more, respectively. It can be set to 1/1000 (60 dB) of 0.46 Oersted, and an extremely high magnetic shielding effect is achieved.

Next, the triple-structure magnetic shield room 10
In, in each chamber 12,24,16, by measuring the central magnetic field in the case of various combinations of PC Permalloy with magnetic permeability μm = 100000 and PC-X with magnetic permeability μm = 336000, The following results were obtained.

[0020] [PC = PC permalloy, the unit of the central magnetic field is 1/10
000000T (Tesla)]

That is, geomagnetism (0.46 Oersted)
1/1000 (60 dB) = 3 / 100000000T
The combination that clears is a combination that uses PC-X for the intermediate chamber 24 and PC permalloy for the inner chamber 16 and the outer chamber 12 and a combination that uses PC permalloy for all chambers 12, 24, 16 is there. Further, the use of PC permalloy for the outer chamber 12 tends to reduce the central magnetic field. It is considered that this is because, as shown in FIG. 7, the magnetic flux density of PC permalloy is higher than the magnetic flux density of PC-X, so that the magnetism from the outside is not easily transmitted to the inside. That is, P
It has been found that a combination of C-permalloy and PC-X in the intermediate chamber 24 or the internal chamber 16 provides a high magnetic shielding effect.

In the embodiment, the double structure and the triple structure are illustrated, but it goes without saying that the structure may be a quadruple structure or more. Further, each room is not limited to a cube but may be a rectangular parallelepiped.

[0023]

As described above, according to the magnetic shield room of the present invention, it is possible to secure a wide indoor space capable of accommodating various measuring devices without enlarging the entire shield room. Further, unlike the conventional magnetically shielded room having a 26-sided body, no space is wasted on the outer circumference, so that space can be saved. Moreover, since a magnetic shielding effect of 60 dB against the earth's magnetism can be obtained, it can be suitably used as a magnetic shield room of a SQUID that detects extremely weak magnetism. In addition, the number of man-hours for designing, molding, assembling, and constructing is small, and the assembly can be accurately performed in a short time and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic vertical cross-sectional view of a magnetic shield room according to a preferred embodiment of the present invention.

FIG. 2 is a graph showing the influence of plate thickness.

FIG. 3 is a graph showing a separation distance between chambers.

FIG. 4 is an explanatory diagram of a test example for measuring an influence of a gap at a joint between plate materials.

FIG. 5 is a graph showing an influence of a gap at a joint between plate materials.

FIG. 6 is a schematic vertical sectional view of a magnetic shield room according to another preferred embodiment of the present invention.

FIG. 7 is a graph showing magnetic characteristic curves of PC permalloy and PC-X.

[Explanation of symbols]

 10 Magnetic Shield Room 12 External Room 14 Insulation 16 Internal Room 20 Plate 24 Intermediate Room

Claims (4)

[Claims] 1. A magnetic structure characterized in that a plurality of hexahedrons made of a plate material having a thickness of 2 mm or more and made of a high-permeability alloy are formed in a multiple structure with an insulating material interposed between them and at a distance of 250 mm or more. Shield room. 2. The magnetically shielded room according to claim 1, wherein the hexagonal structure comprises two hexahedrons to form a double structure. 3. The magnetically shielded room according to claim 1, wherein the magnetic shield room has a triple structure composed of three hexahedrons. 4. The high magnetic permeability alloy is a soft magnetic material F
e-45Ni, 80Ni-Mo-Fe, 78Ni-Mo
-Cu-Fe or 70Ni-10Cu-12Mn-F
The magnetic shield room according to any one of claims 1 to 3, which is e.