JP6049014B2 - Open type magnetic shield structure with door - Google Patents

Description

  The present invention relates to an open type magnetic shield structure with a door, and more particularly to an open type magnetic shield structure in which a magnetic shield target space is surrounded by a belt-like magnetic plate.

  An electron beam application apparatus such as an electron microscope, an EB exposure apparatus, or an EB stepper used in a semiconductor manufacturing facility or the like ensures the product quality because the trajectory of the electron beam changes even with a weak magnetic noise of about 100 nT (1 mG), for example. Therefore, it is necessary to avoid the influence of disturbance magnetic field (environmental magnetic field). In addition, SQUID (superconducting quantum interference device) application devices such as magnetoencephalographs and magnetocardiographs used in medical facilities are required to block disturbance magnetic fields in order to accurately measure weak magnetism. In order to protect a device that does not like the influence of a disturbance magnetic field (magnetomagnetic device) from the disturbance magnetic field and to ensure normal operation, it is required to provide a magnetic shield room (shield space) in the facility.

  The conventional magnetic shield room has a structure that covers the entire floor, wall, and ceiling without any gaps with a plate made of a magnetic material such as PC permalloy (high magnetic permeability μ) or magnetic steel plate (hereinafter referred to as a magnetic plate) (sealed shield structure). And often. On the other hand, as shown in FIG. 13, a magnetic shield structure (hereinafter referred to as an open magnetic shield structure or an open shield structure) 5 in which strip-like magnetic plates are arranged in a bowl shape or a louver shape has been developed (Patent Document). 1-4). The open type shield structure 5 of the illustrated example has a required plate thickness direction interval d such that a plurality of belt-like magnetic plates 2 having, for example, a band width of about 30 to 50 mm are aligned in parallel with the longitudinal center axis C on the same saddle surface F. To form a magnetic shield housing 3 (see FIG. 13A), and a plurality of shield housings 3a, 3b, 3c, 3d are magnetically joined by overlapping (surface contact) 9 of corresponding edges. A band-shaped magnetic plate (hereinafter referred to as a ring-shaped magnetic plate) 4 that is closed in an annular shape is formed, and the shield target space 1 is surrounded by a plurality of ring-shaped magnetic plates 4 (see FIG. 13B).

  In the open type shield structure of FIG. 13B, the mutual distance d of the ring-shaped magnetic plates 4 is set so that the magnetic flux in the magnetic plate 4 is easy to pass (permeance of the magnetic plate). The ratio (Sm · μs / Sa) of the product (Sm · μs) of the cross-sectional area Sm of the magnetic plate 4 and the relative permeability μs to the cross-sectional area Sa of the interval d is greater than 1. It can be designed to be large enough. By designing an appropriate distance d, the space 1 is given openness (permeability, translucency, heat dissipation), and magnetically closed annulus-shaped magnetic plate 4 (magnetic) as shown by the arrows in FIG. The magnetic field is concentrated on the body circuit), and the magnetic field (magnetic shield performance) suitable for the magnetic shield room can be provided by suppressing the intrusion of the disturbance magnetic field M from the interval d. The illustrated example shows the case where the DC magnetic field M is applied, but when the AC magnetic field M is applied, the same effect can be obtained only by changing the direction of the magnetic flux.

  However, in order to apply the open type shield structure of FIG. 13B to a magnetic shield room, it is necessary to provide a relatively large door opening for people and objects to enter and exit. For example, in a magnetic shield room 1 having an open shield structure surrounded by an annular belt-like magnetic plate 4 as shown in FIGS. 10A1 and 10B1, a door opening 11 as shown in FIGS. 10A2 and 10B2. Since the ring-shaped magnetic plate (magnetic circuit) that is magnetically closed is cut, if the door opening 11 is left open, the magnetic shielding performance can be deteriorated. In the sealed shield structure, a magnetic plate is attached to the surface of the door that closes the opening 11, and the magnetic plate of the door is brought into surface contact with the magnetic plate of the floor, wall, or ceiling via the door frame. The door opening can be magnetically closed. On the other hand, in the open shield structure, the ring-shaped magnetic plate (C-shaped magnetic plate 20) cut at the door opening 11 cannot be brought into surface contact with the door surface. Even if it is used, it is difficult to magnetically close the door opening 11.

  As a method of magnetically closing the door opening 11 provided in the open type shield structure, as shown in FIGS. 10 (A3) and (B3), the magnetic shield housing 3 (FIG. 13 (A)) is used to An extension plate (L-shaped angle or the like) 16 made of a magnetic plate is attached to the lengthwise edge of the door, and the door is formed on the edge in the lengthwise direction of the peripheral wall surface of the opening 11 (C-shaped magnetic plate 20). In addition, a method has been proposed in which a magnetic expansion plate 16 is attached and the opposing area is expanded in the thickness direction (see Patent Document 3). Even if there is a slight gap between the door and the surrounding wall surface, if the area where the two faces each other is expanded, it can be expected that the two will be magnetically coupled through the gap to suppress the penetration of the magnetic field. Further, as shown in FIGS. 10A4 and 10B4, an opening frame 17 made of a magnetic plate is provided around the inner side of the door opening 11, and the opening frame 17 is formed into a C-shaped magnetic plate 20 on the peripheral wall surface of the opening 11. Has been proposed (see Patent Document 2). By diverting the magnetic flux through the magnetic opening frame 17, it can be expected that the intrusion of the magnetic field from the cut ring-shaped magnetic plate (C-shaped magnetic plate 20) can be suppressed to a low level.

International Publication No. 2004/084603 Pamphlet JP 2006-269656 A JP 2006-351598 A JP 2007-103854 A

The Institute of Electrical Engineers of Japan Corresponding Education Society "The Institute of Electrical Engineers of Japan, Electrical Materials (Revised)" The Institute of Electrical Engineers of Japan, December 26, 1960

  However, the above-described methods shown in FIGS. 10A3 and 10A4 have a problem that the weak magnetic field entering from the door opening 11 of the open shield structure cannot be sufficiently suppressed. The inventor used an annular belt-like magnetic plate 4 (see FIG. 13B) in which four belt-like magnetic plates 2 (made of PC Permalloy) having a width of 30 mm, a length of 280 mm, and a plate thickness of 0.5 mm were joined in a cross-beam shape. As shown in FIGS. 10 (A1) and (B1), an open type shield structure 5 in which the annular belt-like magnetic plate 4 is stacked in five steps at a thickness direction interval d = 60 mm is created to obtain a magnetic shield performance 5. An experiment to confirm was conducted. In the experiment, an open shield structure 5 is installed at the center of the annular coil L shown in FIG. 12A, and a substantially uniform weak magnetic field M (10 μT, DC magnetic field) in the X and Y directions is sequentially applied. The magnetic field strengths at the evaluation points S1 to S5 in the inner space 1 were measured by the magnetic sensor 8, respectively. Further, when the magnetic field strength at each of the evaluation points S1 to S5 of the same open shield structure 5 was analyzed by a numerical simulation (three-dimensional nonlinear magnetic field analysis), an analytical value almost coincident with the experimental value was obtained. Therefore, weak magnetic fields M in the X and Y directions were applied in an open shield structure having a 94 mm wide door opening 11 as shown in FIGS. 10 (A2), 10 (A3), and 10 (A4). A verification experiment was performed in which the magnetic field strengths of the evaluation points S1 to S5 at the time were respectively obtained by numerical simulation and compared with the magnetic field strengths (reference values of the magnetic field strength) of the evaluation points S1 to S5 before the opening 11 was provided.

  The graph of FIG. 11A2 shows the magnetic field strength (ratio to the reference value) of the evaluation points S1 to S5 of the open type shield structure with the door opening 11 opened as shown in FIG. The average magnetic field strength (ratio of the reference value to the average) is shown. Further, the graph of FIG. 11A3 shows the evaluation points S1 to S5 of the open type shield structure in which the door 3 with the magnetic expansion plate 16 and the periphery of the opening face each other with a required gap (width 5 mm) as shown in FIG. 10A3. The magnetic field strength (ratio to the reference value) and the average magnetic field strength at 5 points (ratio to the average of the reference value) are shown. As can be seen from the comparison of both graphs, by providing the door 3 with the magnetic expansion plate 16 in the opening 11, the magnetic field at the evaluation point S2 near the opening can be reduced with respect to the magnetic field in the X direction, but the other evaluation points S1, S3 The magnetic field of .about.S5 cannot be made sufficiently small. Further, although the magnetic field in the inner space 1 can be reduced as a whole with respect to the Y-direction magnetic field, the magnetic field at the evaluation point S2 cannot be sufficiently reduced. From this experimental result, it is difficult to obtain a sufficient magnetic shielding effect in the entire inner space 1 of the open shield structure for the weak magnetic field M only by attaching the magnetic expansion plate 16 to the door 3 of the opening 11. I understand.

  Further, the graph of FIG. 11A4 shows the evaluation points S1 to S5 of the open type shield structure in which the magnetic opening frame 17 having the required thickness (0.5 mm) is provided to bypass the magnetic flux as shown in FIG. 10A4. The magnetic field strength (ratio to the reference value) and the average magnetic field strength at 5 points (ratio to the average of the reference value) are shown. As can be seen from a comparison between FIG. 11 (A4) and FIG. 11 (A2), by providing the magnetic aperture frame 17 in the opening 11, the magnetic field at the evaluation point S3 away from the opening can be reduced with respect to the X-direction magnetic field. , The magnetic fields of the other evaluation points S1 to S2 and S4 to S5 are larger. Further, the magnetic field is generally increased with respect to the Y-direction magnetic field, and in particular, the magnetic field at the evaluation point S2 is increased. From this experimental result, it can be seen that even if the magnetic aperture frame 17 is provided in the opening 11, a sufficient magnetic shielding effect cannot be obtained in the entire inner space 1 of the open shield structure for the weak magnetic field M.

  The experimental result of FIG. 11 (A4) shows that the provision of the magnetic aperture frame 17 disrupts the overall arrangement balance of the magnetic material, and the magnetic flux flowing in the magnetic circuit becomes asymmetrical, resulting in a place where the magnetic flux does not flow easily. This suggests that the magnetic field in space 1 has increased overall. 11A3 shows that when the surface direction of the magnetic expansion plate 16 is different from the direction of the magnetic field M to be applied, it is difficult for the magnetic flux to flow in the magnetic circuit, and there is a place where the magnetic field increases in the internal space 1. Suggests that it will occur. In order to apply the open type shield structure to the magnetic shield room having the opening 11, the door opening 11 can be magnetically closed without disturbing the magnetic flux flowing through the magnetic circuit, and the weak magnetic field entering from the opening 11 can be prevented. There is a need for a technique that can be sufficiently suppressed to obtain a sufficient magnetic shielding effect in the entire inner space 1.

  Accordingly, an object of the present invention is to provide an open type magnetic shield structure with a door which can obtain a sufficient magnetic shield effect in the entire inner space.

Referring to the embodiment of FIG. 1, an open type magnetic shield structure with a door according to the present invention has a first direction axis Az penetrating the magnetic shield target space 1 with an opening 11 of the door 12 in parallel with the door 12 and a predetermined distance dz. in a plurality of parallel planes which intersect Pz1, Pz2, respectively provided on ...... and the 1C-shaped magnetic plate strip cut in the door opening 11 while surrounding the space 1 20z1,20z2, ......, first A plurality of planes Pz1, Pz2,... Intersecting the direction axis Az are arranged on the door 12 along the intersecting line with the door 12 closing the opening 11, respectively, and perpendicular to the band width surface of the first C-shaped magnetic plate; mutually insulated multiple strip of the 1I-shaped magnetic plate 23z (23z1,23z2, ......), the 1C-shaped magnetic plates 20Z1,20z2, the 1I-shaped magnetic across each cutting portion of ...... Take so as to face the plate 23z The L-shaped angle-shaped connecting magnetic body 26z (26z1, 26z2,...) And the first C-shaped magnetic plates 20z1, 20z2,... Via the connecting magnetic body 26z when the door opening 11 is closed. The first I-shaped magnetic plates 23z1, 23z2,.

Preferably, as shown in FIG. 2, the first C is respectively formed on a plurality of parallel planes Px1, Px2,... Intersecting a second direction axis Ax penetrating the magnetic shield target space 1 in parallel with the door 12 at a predetermined interval dx . shaped magnetic plate 20z1,20z2, ...... and telescopically arranged and cut in the door opening 11 while surrounding the space 1 a strip of the 2C-shaped magnetic plate 20x1,20x2, ......, a second direction axis Ax A plurality of planes Px1, Px2,... Intersecting with the door 12 are respectively arranged on the door 12 at right angles to the band width surface of the second C-shaped magnetic plate and insulated from each other and the first C A plurality of strip-shaped second I-shaped magnetic plates 23x (23x1, 23x2,...) Insulated from the letter-shaped magnetic plates 23z (23z1, 23z2,...), And the second C-shaped magnetic plates 20x1, 20x2,. Both ends of each cutting part The connecting magnetic 26x of the L-shaped angle shape mounted so as to face the first 2I-shaped magnetic plate 23x provided, the 2C-shaped magnetic plate through the magnetic 26x tether during closing of the door opening 11 by the pressing mechanism 20x1, 20x2,... And the second I-shaped magnetic plates 23x1, 23x2,.

  More preferably, as shown in FIG. 3, each space is placed on a plurality of parallel planes Py1, Py2,... Intersecting a third direction axis Ay passing through the magnetic shield target space 1 perpendicularly to the door 12 at a predetermined interval dy. Are provided around the space 1, and the first C-shaped magnetic plates 20z1, 20z2,... And the second C-shaped magnetic plates 20x1, 20x2,. The plates 20y1, 20y2,... Are arranged in a nested manner.

  In a more preferred embodiment, the first C-shaped magnetic plate 20z, the second C-shaped magnetic plate 20x, and the ring-shaped magnetic plate 20y are arranged in a nested manner around the magnetic shield target space 1 as shown in FIG. As shown in FIG. 4, a strip-shaped first C-shaped conductor cut by a door opening 11 while surrounding the magnetic shield target space 1 at intervals dz between a plurality of first C-shaped magnetic plates 20z intersecting the first direction axis Az. The plate 30z is provided, the conductor opening frame 32 is fixed around the inside of the opening 11, and both ends of the cut portion of each first C-shaped conductor plate 30z are electrically joined to the conductor opening frame 32.

  As shown in FIG. 5A, instead of or in addition to the first C-shaped conductor plate 30z, magnetic shield target spaces are respectively provided at intervals dx between the plurality of second C-shaped magnetic plates 20x intersecting the second direction axis Ax. 1, a belt-like second C-shaped conductor plate 30 x that is cut by the door opening 11 may be provided, and both ends of the cut portion of each second C-shaped conductor plate 30 x may be electrically joined to the conductor opening frame 32. . Further, as shown in FIG. 5B, instead of or in addition to the first C-shaped conductor plate 30z and the second C-shaped conductor plate 30x, a plurality of annular belt-shaped magnetic plates 20y intersecting the third direction axis Ay. An annular belt-shaped conductor plate 30y that surrounds the magnetic shield target space 1 can also be provided at intervals dy.

According to the open type magnetic shield structure with a door of the present invention, a plurality of parallel planes Pz1, Pz2,... On the first direction axis Az penetrating the magnetic shield target space 1 in parallel with the door 12 at a predetermined interval dz. C-shaped magnetic plates 20z1, 20z2,... Cut by the door opening 11 while surrounding the space 1, respectively, and a plurality of planes Pz1, Pz2,... And the opening 11 intersecting the first direction axis Az. A plurality of strip-shaped I-shaped magnetic plates 23z1, 23z2,... Are arranged on the door 12 while being insulated from each other along the line of intersection with the door 12 to be closed , and the C-shaped magnetic plates 20z1, 20z2,. The connecting magnetic body 26z is attached to both ends of each cut portion so as to face the I-shaped magnetic plates 23z1, 23z2,... When the door 12 is closed, and the C-shaped magnetic plate 20z1 is connected via the connecting magnetic body 26z. , 20z2, ...... and I Type magnetic plate 23Z1,23z2, since the in close contact to magnetically joining ..., the following effects can be obtained.

(A) The connecting magnetic body 26z attached to the C-shaped magnetic plate 20z is opposed to the door magnetic plate 22, and the C-shaped magnetic plate 20z and the door magnetic plate 22 are brought into surface contact with each other when the door 12 is closed. The door opening 11 can be magnetically closed while ensuring the continuity of the body circuit.
(B) Further, the door magnetic plate 22 is formed by a plurality of I-shaped magnetic plates 23z1, 23z2,... Provided while being insulated from each other along the intersecting line with the plurality of planes Pz1, Pz2,. And each of the C-shaped magnetic plate 20z and the I-shaped magnetic plate 23z are magnetically joined to each other while being insulated from each other, so that the magnetic flux flowing in each of the magnetic circuits is not disturbed. 11 can be magnetically closed.
(C) By magnetically closing the door opening 11 without disturbing the magnetic flux flowing in the magnetic circuit, a sufficient magnetic shielding effect can be obtained in the entire inner space when the door 12 is closed.
(D) Further, a C-shaped conductor plate 30z that is cut by the door opening 11 while surrounding the space 1 is provided at intervals dz between the plurality of C-shaped magnetic plates 20z, and a conductor opening frame 32 is provided around the inside of the opening 11. By fixing and electrically joining both ends of the cut portion of the C-shaped conductor plate 30z to the conductor opening frame 32, an open shield structure combining a magnetic circuit and a conductor circuit can be obtained.
(E) While the open shield structure with a magnetic circuit can degrade the magnetic shield performance at high frequencies, the open shield structure with a conductor circuit improves the magnetic shield performance at high frequencies. Thus, an open type shield structure that exhibits high magnetic shielding performance in a relatively wide frequency range can be obtained.

Hereinafter, embodiments and examples for carrying out the present invention will be described with reference to the accompanying drawings.
It is explanatory drawing of one Example of the open type | mold shield structure by this invention. It is explanatory drawing of the other Example of the open type shield structure by this invention. It is explanatory drawing of other Example of the open type shield structure by this invention. It is explanatory drawing of one Example of the magnetic shield structure of this invention which used the conductor circuit together. It is explanatory drawing of the other Example of the magnetic shield structure of this invention which used the conductor circuit together. It is the experimental result which verified the magnetic shielding performance of inner space by the open type shield structure of FIG. It is the experimental result which verified the magnetic shielding performance of inner space by the open type shield structure of FIG. It is explanatory drawing of the Example which applied the open type shield structure by this invention to the magnetic shield room. It is an enlarged view of the ellipse part VIII of FIG. It is explanatory drawing of the prior art which closes opening of an open type shield structure. It is the experimental result which verified the magnetic shielding performance by the prior art of FIG. It is explanatory drawing of the experimental method which verifies the magnetic shielding performance of an open type shield structure. It is explanatory drawing of an open type shield structure. It is explanatory drawing of the open type shield structure using a conductor circuit.

  FIG. 1 shows an embodiment in which an open shield structure with a door of the present invention is applied to a magnetic shield target space 1 (for example, a magnetic shield room) 1 having a door opening 11. As shown in FIG. 1A, the open type shield structure of the illustrated example includes a plurality of parallel planes Pz1, Pz2, and a first direction axis Az that penetrates the magnetic shield target space 1 in parallel with the door 12 and intersects at a predetermined interval dz. .., And as shown in FIG. 1B, the first C-shaped magnetic plates 20z1, 20z2 are arranged on the planes Pz1, Pz2,... So as to surround the space 1 with a predetermined band width Wc. ,... Are attached on the door 12 so as to face the door magnetic plate 22 on the door magnetic plate 22 arranged in parallel with the first direction axis Az and the C-shaped magnetic plates 20z1, 20z2,. The connecting magnetic bodies 26z, 26z,... In the illustrated example, each plane Px is orthogonal to the first direction axis Az, but the crossing angle may be other than orthogonal. Further, the center point O in the target space 1 passing through the first direction axis Az can be set, for example, as the installation position of the anaerobic device in the target space 1.

  The C-shaped magnetic plate 20z in the illustrated example is cut at the portion of the door opening 11 while surrounding the space 1 on each plane Pz as shown in FIG. 1C. For example, as shown in FIG. Similarly, it is made by using a PC permalloy or other strip-shaped magnetic plate 2 having a high magnetic permeability μ and arranging the strip-shaped magnetic plate 2 in a polygonal shape and joining along the intersecting line between the inner surface of the target space 1 and each plane Pz. it can. Desirably, the strip-shaped magnetic plate 2 constituting the C-shaped magnetic plate 20 is a laminated magnetic plate in which a plurality of PC permalloy thin plates and insulating thin strips are alternately stacked. It is known that the magnetic properties of PC permalloy are higher as they are thinner. Furthermore, by laminating them to the required plate thickness t via an insulating ribbon, the eddy current flowing in the cross section (eddy current loss) is suppressed to a low level. A decrease in magnetic shield performance in the frequency range can be suppressed. An example of the insulating ribbon material is paper or resin in the form of a sheet or film (thickness of 30 μm or less).

  Further, as shown in FIG. 1D, the door magnetic plate 22 on the door 12 is respectively along the intersection line between the planes Pz1, Pz2,... Intersecting the first direction axis Az and the door body 12. A plurality of strip-shaped first I-shaped magnetic plates 23z1, 23z2,... Arranged on the door body 12 while being insulated from each other. For example, the door body 12 is made of non-magnetic stainless steel (SUS), and a belt-like magnetic plate 2 similar to the C-shaped magnetic plate 20z is fixed thereon to form an I-shaped magnetic plate 23z. Ensure electrical insulation between them. Preferably, the I-shaped magnetic plate 23z is a laminated magnetic plate in which PC permalloy thin plates having the same band width and thickness as the C-shaped magnetic plate 20z are alternately stacked with an insulating thin strip material. By making the C-shaped magnetic plate 20z and the I-shaped magnetic plate 23z into strip-shaped magnetic plates having the same band width and thickness, as will be described later, turbulence of magnetic flux flowing in the magnetic circuit that magnetically couples the two is described later. Can be kept small. However, the door magnetic plate 22 is not limited to the I-shaped magnetic plate 23z. For example, as shown in FIG. 1F, the plate-like magnetic plate 24 provided on the surface of the door 12 parallel to the first direction axis Az. It is also possible.

  The connecting magnetic body 26z attached on the C-shaped magnetic plate 20z is attached to both ends facing the cut portion of each C-shaped magnetic plate 20z, and is disposed at right angles to the band width surface of the C-shaped magnetic plate 20z. For example, an L-shaped angle made of a magnetic plate as shown in FIG. 1E can be used so as to face the door magnetic plate 22 on the door 12. By making the C-shaped magnetic plate 20z and the door magnetic plate 22 face each other through the connecting magnetic body 26z, the continuity of the magnetic circuit is ensured when the door 12 is closed, and the door opening 11 is made magnetic. Can be closed.

  FIG. 6A shows an inner side when a magnetic field M in the X direction and the Y direction is applied in the open type shield structure with a door in which the first I-shaped magnetic plate 23z shown in FIG. The magnetic field strength at the evaluation points S1 to S5 in the space 1 is obtained by the above-described numerical simulation (three-dimensional nonlinear magnetic field analysis), and compared with the magnetic field strength (reference value of the magnetic field strength) at the evaluation points S1 to S5 before the opening 11 is provided. The result of a verification experiment is shown. From the comparison between the graph of FIG. 6A and the graph of FIG. 11A2, it can be seen that the magnetic field in the inner space 1 can be reduced as a whole with respect to the magnetic field in the X direction. Further, although the magnetic field at the evaluation point S2 near the opening is slightly increased with respect to the Y-direction magnetic field, the magnetic field in the inner space 1 can be reduced as a whole. From this experimental result, the magnetic flux flowing in each magnetic circuit is disturbed by magnetically joining each of the plurality of I-shaped magnetic plates 23z with the C-shaped magnetic plate 20z in a one-to-one manner while being insulated from each other. It can be seen that the door opening 11 can be magnetically closed, and as a result, a sufficient magnetic shielding effect can be obtained in the entire inner space.

  FIG. 6B shows an open-type shield that uses a plate-like magnetic plate 24 shown in FIG. 1F as the door magnetic plate 22 in place of the first I-shaped magnetic plate 23z shown in FIG. 1D. The verification experiment result which calculated | required the magnetic field intensity in evaluation point S1-S5 of the inner space 1 when the magnetic field M of a X direction and a Y direction was applied to the structure by numerical simulation is shown. From the comparison between the graph of FIG. 6B and the graph of FIG. 11A2, the variation of the magnetic field due to the evaluation points S1 to S5 in the inner space 1 with respect to the magnetic field in the X direction is large, and the evaluation point S1 that is the central point It can be seen that the magnetic field at the evaluation point S3 far from the opening is very small, but the magnetic field at the evaluation point S2 near the opening is large. Also, the magnetic field variation at the evaluation points S1 to S5 is large with respect to the Y-direction magnetic field, and the magnetic fields at the evaluation points S1 and S3 are small. The magnetic field is increasing. From this experimental result, when the door opening 11 is closed by the plate-shaped magnetic plate 24, the balance of the magnetic material arrangement is lost and the magnetic flux flowing in the magnetic material circuit is biased. It is thought to increase. However, FIG. 6B uses a plate-like magnetic plate 24 in place of the I-shaped magnetic plate 23z in order to keep the magnetic field of a specific part (for example, the evaluation point S1 as the central point) of the inner space 1 small. Shows that it is effective.

  In the open shield structure with a door of the present invention, if necessary, the C-shaped magnetic plate 20z and the door magnetic plate 22 are magnetically joined and integrated with each other via a connecting magnetic body 26z. They can be brought into contact with each other by applying appropriate pressure. For example, by diverting a pressing mechanism (for example, a mechanism constituted by a roller throttle handle, a side roller throttle via a rod, etc.) used in a conventional magnetic shield door with a hermetic shield structure, the door magnetic plate 22 is used. A pressing force can be applied to increase the degree of adhesion with the C-shaped magnetic plate 20z.

  Thus, the provision of an “open type magnetic shield structure with a door capable of obtaining a sufficient magnetic shielding effect in the entire inner space”, which is an object of the present invention, can be achieved.

  Preferably, as shown in FIG. 2A, a plurality of parallel planes Px1, Px2,... Intersecting the second direction axis Ax penetrating the magnetic shield target space 1 in parallel with the door 12 at a predetermined interval dx is assumed. On the planes Px1, Px2,..., Band-shaped second C-shaped magnetic plates 20x1, 20x2,... Cut around the door opening 11 while surrounding the space 1 with a predetermined band width Wc are provided. 1C-shaped magnetic plates 20z1, 20z2,... In FIG. 1B and second C-shaped magnetic plates 20x1, 20x2,. In FIG. 2, the second direction axis Ax is selected in a direction different from the first direction axis Az in FIG. 1, for example, a direction perpendicular to the direction axis Az. Further, the intersection angle between each plane Px and the second direction axis Ax may be other than orthogonal.

  As shown in FIG. 2 (B), both ends of each cut portion of the second C-shaped magnetic plate 20x are joined to face the door magnetic plate 22 in the same manner as the first C-shaped magnetic plate 20z. Install 26x. Then, the C-shaped magnetic plate 20x and the door magnetic plate 22 are opposed to each other through the connecting magnetic body 26x and are brought into surface contact with each other, thereby ensuring the continuity of the magnetic circuit when the door 12 is closed. The door magnetic plate 22 may be a plate-like magnetic plate 24 as shown in FIG. 1 (F), but a plurality of planes Px1, Px2,... Intersecting with the second direction axis Ax as shown in the example. And a plurality of strip-shaped second I-shaped magnetic plates 23x (23x1, 23x2,...) Provided while being insulated from each other along the line of intersection with the door 12.

  Although the open shield structure of FIG. 1A cannot cope with the disturbance magnetic field M in the Z direction (the direction of the first direction axis Az), the first C-shaped magnetic plate 20z and the second C-shaped magnetic plate 20x are combined. According to the open type shield structure of FIG. 2A, a high magnetic shielding effect can be expected even with respect to the external magnetic field M in the Z direction. Also, the door magnetic plate 22 is constituted by the first I-shaped magnetic plate 23z of FIG. 1B and the second I-shaped magnetic plate 23x of FIG. The plates 23z and 23x are magnetically joined to the C-shaped magnetic plates 20z and 20x on a one-to-one basis while insulating the plates 23z and 23x from each other, thereby magnetically opening the door opening 11 without disturbing the magnetic flux flowing in each magnetic circuit. Can be closed.

  More preferably, as shown in FIG. 3A, a plurality of parallel planes Py1, Py2,... Intersecting with the third direction axis Ay penetrating the magnetic shield target space 1 perpendicularly to the door 12 at a predetermined interval dy. Assuming that ring-shaped magnetic plates 20y1, 20y2,... Surrounding the space 1 are provided on the planes Py1, Py2,..., Respectively, and the first C-shaped magnetic plate 20z1 of FIG. , 20z2,... And two layers of the ring-shaped magnetic plates 20y1, 20y2,. Alternatively, the first C-shaped magnetic plates 20z1, 20z2,... Of FIG. 1B and the second C-shaped magnetic plates 20x1, 20x2,... Of FIG. The three layers of the ring-shaped magnetic plates 20y1, 20y2,. Since the ring-shaped magnetic plate 20y does not intersect the door opening 11, it can be a band-shaped magnetic plate closed in an annular shape without a cut portion.

  In FIG. 3, the third direction axis Ay is selected in a direction different from any of the first direction axis Az in FIG. 1 and the second direction axis Ax in FIG. 2, for example, a direction perpendicular to both of the direction axes Az and Ax. In addition, the crossing angle between each plane Py and the third direction axis Ay may be other than orthogonal. The open shield structure of FIG. 2A can shield the disturbance magnetic field M whose direction is not determined (can come from all directions), but all the planes surrounding the shield target space 1 (XZ plane, XY). According to the open type shield structure of FIG. 3A in which two layers of magnetic circuits are arranged on each of the plane and the YZ plane, a high magnetic shielding effect against the disturbance magnetic field M whose direction is not determined can be expected. .

  The open type magnetic shield structure with a door using a magnetic circuit has been described above. However, an open type magnetic shield structure using a magnetic circuit is not necessary if the disturbance magnetic field is a direct current or a low frequency alternating current of several Hz or less. Although the magnetic shield performance is as designed, there is a problem that the shield performance deteriorates in the high frequency range from 10 Hz to the commercial frequency or higher. In the graph of FIG. 12B, the open type shield structure shown in FIGS. 10A1 and 10B1 is installed at the center of the annular coil L of FIG. 12A, and the frequencies are 1 Hz, 10 Hz, 60 Hz, and 200 Hz. The measured value of the magnetic field strength at the inner center when a substantially uniform magnetic field M (10 μT) is applied while switching to is shown. The graph shows that as the frequency of the applied magnetic field M increases, the magnetic field strength at the inner center of the open shield structure increases, that is, the magnetic shield performance decreases. The reason why the magnetic shield performance deteriorates in the high frequency range is presumed to be that eddy current (eddy current loss) is generated in the ring-shaped magnetic plate 4 (magnetic circuit) by electromagnetic induction.

  On the other hand, it is known that a magnetic shield structure using an eddy current flowing in a conductor plate by electromagnetic induction works more effectively as the frequency is higher (see Non-Patent Document 1). Therefore, as shown in FIG. 14A, a ring-shaped conductor plate 6 having a width of 30 mm is prepared using a copper and aluminum conductor plate having an outer dimension of 280 mm × 280 mm and a plate thickness of 5 mm. An open type shield structure in which (conductor circuit) is stacked in five steps at a plate thickness direction interval d = 60 mm is installed at the center of the annular coil L in FIG. 12A so that the central axis direction coincides with the magnetic field direction. An experiment was conducted to measure the magnetic field strength (experimental value) at the inner center when a substantially uniform magnetic field M (10 μT) of 1 Hz, 10 Hz, 60 Hz, and 200 Hz was applied. The experimental results in FIG. 14B show that the magnetic field strength at the inner center of the open shield structure decreases as the frequency of the applied magnetic field M increases, that is, the magnetic shield performance improves. In addition, when the magnetic field strength at the inner center of the same open shield structure was analyzed by numerical simulation based on eddy current (three-dimensional nonlinear magnetic field analysis), an analytical value almost in agreement with the experimental value as shown in FIG. Obtained. This graph shows that the magnetic shielding performance of copper, which has higher conductivity than aluminum, is higher.

  The magnetic shield performance of the open shield structure shown in FIGS. 10A1 and 10B1 using the ring-shaped magnetic plate 4 (magnetic circuit) decreases as the frequency of the applied magnetic field M increases (FIG. 12B 14), the magnetic shield performance of the open shield structure of FIG. 14A using the ring-shaped conductor plate 6 (conductor circuit) is improved as the frequency of the applied magnetic field M is increased (see FIG. 14B). ), And by combining them, it is possible to obtain an open shield structure in which the shield performance is not deteriorated even with respect to a disturbance magnetic field M in a high frequency range (10 Hz to a commercial frequency or higher). (See Japanese Patent Application No. 2012-236166).

  FIG. 4 shows an embodiment of an open type shield structure with a door according to the present invention in which a magnetic circuit and a conductor circuit are combined. The open type shield structure of the illustrated example has a first C-shaped magnetic plate 20z1, 20z2,... In FIG. 1B and a second C-shaped magnetic plate 20x1, 20x2 in FIG. ,... And the annular belt-like magnetic plates 20y1, 20y2,... Of FIG. 3B are arranged in a nested manner, and the magnetic shield target space 1 is parallel to the door 12 as shown in FIG. As shown in FIG. 4B, the door opening 11 surrounds the space 1 at intervals dz of the plurality of first C-shaped magnetic plates 20z1, 20z2,... Intersecting the first direction axis Az that penetrates at a predetermined interval dz. The first C-shaped conductor plates 30z1, 30z2,..., Which are cut in the above, are arranged, the conductor opening frame 32 is fixed around the inside of the door opening 11, and the first C-shaped conductor plates 30z1, 30z2,. Electrically connect both ends of the cut portion to the conductor opening frame 32 One in which engaged.

  For example, as shown in FIG. 4C, the C-shaped conductor plate 30z is formed along a cross line between a plane Px intersecting the inner surface of the target space 1 and the first direction axis Az and the inner surface of the target space 1. It can be created by joining a plurality of strip-shaped conductor plates having a width Wm and an appropriate length. Since the magnetic shielding effect can vary greatly depending on the contact resistance of the joint, it is possible to cut out the C-shaped conductor plate 30z from one large conductor plate instead of the method of joining a plurality of strip-like conductor plates. is there. The material of the C-shaped conductor plate 30z can be appropriately selected according to the shielding performance required for the target space 1 from an appropriate conductor plate such as copper or aluminum, but as described above, the shielding performance is high when the conductivity is large. Therefore, it is desirable to use a material with high conductivity.

  Moreover, the conductor opening frame 32 fixed to the door opening 11 can be made of the same conductor plate as the C-shaped conductor plate 30z. For example, as shown in FIG. 4D, connecting conductors 36z, 36z,... Such as L-shaped angles are attached to both ends facing the cut portion of each C-shaped conductor plate 30z, and each C-shape is connected by the connecting conductor 36z. By electrically joining both ends of the cut portion of the mold conductor plate 30z to the conductor opening frame 32, the continuity of the conductor circuit can be secured and the door opening 11 can be electrically closed. Since the magnetic shield effect can vary greatly depending on the contact resistance of the joint portion, for example, a mirror-like finished surface is formed at each joint portion between the both ends of the cut portion of the C-shaped conductor plate 30z and the conductor opening frame 32. It is desirable to join them by overlapping each other and pressing them (see Japanese Patent Application No. 2012-276652 which is the prior application of the present inventors).

  The graphs of FIGS. 7 (S1) to (S5) show an open type shield structure (no opening) shown in FIG. 14 (A) using a copper ring-shaped conductor plate 6 having an outer dimension of 280 mm × 280 mm and a thickness of 5 mm, 94 mm. An open type shield structure (with no frame) with the width door opening 11 provided, and an open type shield structure (frame with the same structure shown in FIG. 4B) in which a conductor opening frame 32 is provided around the inner side of the door opening 11 with a width of 94 mm. 4 models (2 models of 5 mm and 10 mm of frame) are used, and the magnetic field strength at the evaluation points S1 to S5 in the inner space 1 when the magnetic field M in the central axis direction is applied to each of the numerical simulations (three-dimensional nonlinear magnetic field) The result of the verification experiment obtained by (Analysis) is shown. From the graph of FIG. 7, it can be seen that the magnetic shield effect cannot be obtained because the eddy current does not flow when the door opening 11 is left open (no frame). In addition, when the opening frame 32 is provided, it can be seen that a magnetic shield performance close to that without the opening can be obtained except that the magnetic field is slightly increased at the evaluation point S2 near the opening.

  In the open shield structure with a door in FIG. 4A, the conductor circuit composed of the first C-shaped conductor plate 30z and the conductor opening frame 32 is subjected to a disturbance magnetic field M in the central axis direction (the direction of the first direction axis Az). Shield performance is demonstrated. Further, the magnetic circuit composed of the second C-shaped magnetic plate 20x and the door magnetic plate 22 and the magnetic circuit composed of the ring-shaped magnetic plate 20y also exhibit shielding performance against the disturbance magnetic field M having the first direction axis Az. . Therefore, as shown in FIG. 4B, the C-shaped conductor plate 30z surrounding the magnetic shield target space 1 is disposed and the conductor opening frame 32 is disposed on the door 12, thereby arriving from the direction of the first direction axis Az. The decrease in magnetic shield performance in the high frequency range of the magnetic circuit against the disturbance magnetic field M can be compensated by improving the magnetic shield performance in the high frequency range of the conductor circuit, and the high frequency range coming from the direction of the first direction axis Az. It can be set as the open type shield structure with a door which shield performance does not deteriorate with respect to the disturbance magnetic field M (10 Hz-commercial frequency or more).

  Further, in the shield target space in which the first C-shaped magnetic plate 20z, the second C-shaped magnetic plate 20x, and the ring-shaped magnetic plate 20y are arranged in a nested manner as shown in FIG. In place of or in addition to the first C-shaped conductor plate 30z, a plurality of second C-shaped crossings intersecting the second direction axis Ax penetrating the magnetic shield target space 1 in parallel with the door 12 as shown in FIG. A band-shaped second C-shaped conductor plate 30x that is cut at the door opening 11 while surrounding the space 1 is arranged at intervals dx of the magnetic plates 20x, and both ends of the cut portions of the second C-shaped conductor plates 30x are opened to the conductor. It is also possible to electrically join the frame 32. The conductor circuit composed of the second C-shaped conductor plate 30x and the conductor opening frame 32 exhibits shielding performance against the disturbance magnetic field M in the central axis direction (direction of the second direction axis Ax). By arranging the C-shaped conductive plate 30x surrounding the space 1 and arranging the conductor opening frame 32 on the door 12, the high frequency of the magnetic circuit against the disturbance magnetic field M coming from the direction of the second direction axis Ax The decrease in magnetic shield performance in the high frequency range can be compensated by improving the magnetic shield performance in the high frequency range of the conductor circuit.

  Further, as shown in FIG. 4A, in the shield object space in which the first C-shaped magnetic plate 20z, the second C-shaped magnetic plate 20x, and the ring-shaped magnetic plate 20y are arranged in a nested manner, the above-described FIG. Instead of or in addition to the first C-shaped conductor plate 30z and the second C-shaped conductor plate 30x of FIG. 5A, the magnetic shield target space 1 passes through the door 12 perpendicularly as shown in FIG. 5B. It is also possible to provide ring-shaped conductor plates 30y surrounding the magnetic shield target space 1 at intervals dy between the plurality of ring-shaped magnetic plates 20y intersecting the third direction axis Ay. The conductor circuit composed of the ring-shaped conductor plate 30y exhibits shielding performance against the disturbance magnetic field M in the central axis direction (the direction of the third direction axis Ay), and therefore surrounds the space 1 as shown in FIG. By disposing the annular belt-like conductor plate 30y, the magnetic shield performance in the high frequency region of the conductor circuit is reduced with respect to the disturbance magnetic field M coming from the direction of the third direction axis Ay. It can be compensated for by improvement.

8A shows the first C-shaped magnetic plate 20z of FIG. 1B, the second C-shaped magnetic plate 20x of FIG. 2B, the ring-shaped magnetic plate 20y of FIG. 3B, and FIG. The magnetic shield room 1 of the present invention in which the first C-shaped conductor plate 30z of B), the second C-shaped conductor plate 30x of FIG. 5A, and the ring-shaped conductor plate 30y of FIG. Examples of The illustrated example shows a front view of a door 12 made of non-magnetic stainless steel (SUS) in the magnetic shield room 1, and a PC permalloy thin plate having a width of 50 mm and a thickness of 0.5 mm is formed on the peripheral wall as a magnetic circuit. A first C-shaped magnetic plate 20z (outer layer) and a second C-shaped magnetic plate 20x (inner layer) made of laminated magnetic plates (total thickness 4 mm) are arranged at intervals of 200 mm in the horizontal direction and the vertical direction, respectively. Yes. In addition, a copper first C-shaped conductor plate 30z (outer layer) and a second C-shaped conductor plate 30x (inner layer) having a width of 50 mm and a thickness of 5 mm are disposed as conductor circuits at intervals of 200 mm in the horizontal direction and the vertical direction, respectively. Yes. Further, the door 12 has a pressure mechanism (for example, a roller throttle handle, a roller throttle handle, a lift) used as a magnetic shield door having a conventional sealed shield structure as a pressing mechanism that can be held, rotated, and locked (opened / closed). Hinges, rods, side roller throttles, etc.) are attached.

  As shown in FIG. 8B, on the outer layer of the door 12, the planes Pz1, Pz2,... Intersecting the first direction axis Az and the door main body 12 as described above with reference to FIG. A plurality of strip-shaped first I-shaped magnetic plates 23z are arranged along the line of intersection with each other while being insulated from each other. 8C, the inner layer of the door 12 includes the planes Px1, Px2,... Intersecting the second direction axis Ax as shown in FIG. A plurality of strip-shaped second I-shaped magnetic plates 23x are arranged along the crossing line while being insulated from each other. The I-shaped magnetic plates 23z and 23x can be fastened and fixed to the door body 12 with a stainless steel screw or the like within a range where the magnetic characteristics of the PC permalloy are not deteriorated by stress. Further, as shown in FIG. 8 (E), a conductor opening frame 32 is fixed around the inner side of the inner layer of the door 12, and as shown in FIGS. 8 (D) and (E), the first C-shaped conductor plate 30z. The (outer layer) and the second C-shaped conductor plate 30x (inner layer) are electrically joined to the conductor opening frame 32 via L-shaped connecting conductors 36z and 36x, respectively.

  9A is a partially enlarged front view of the ellipse VIII in FIG. 8, and FIGS. 9B and 9C are cross-sectional views taken along lines BB and CC in FIG. 9A. . As shown in FIG. 9C, the connecting magnetic body 26z for magnetically joining the first C-shaped magnetic plate 20z (outer layer) and the first I-shaped magnetic plate 23z (outer layer) is a C-shaped magnetic plate 20z. L-shaped angle members 27z attached to both ends of the cut portion, a projecting member 28z projecting from the angle member 27z into the door opening 11, and a covering member 29z having a U-shaped cross section extending to the periphery of the door body 12. It is comprised by. The angle member 27z and the overhang member 28z are magnetically coupled to the C-shaped magnetic plate 20z while being in surface contact with each other using, for example, a stainless steel bolt. Further, the covering member 29z is magnetically connected to the I-shaped magnetic plate 23z using, for example, a stainless steel screw and brought into surface contact with the protruding member 28z when the door 12 is closed. Horizontal continuity is ensured.

  As shown in FIG. 9B, the connecting magnetic body 26x that magnetically bonds the second C-shaped magnetic plate 20x (inner layer) and the second I-shaped magnetic plate 23x (inner layer) is also C-shaped magnetic. An L-shaped angle member 27x attached to both ends of the cut portion of the plate 20x, a projecting member 28x projecting from the angle member 27x into the door opening 11, and a U-shaped covering extending to the periphery of the door body 12 It is comprised by the member 29x. The angle member 27x and the projecting member 28x are magnetically coupled to the C-shaped magnetic plate 20x while being in surface contact with each other, and the covering member 29x is magnetically coupled to the I-shaped magnetic plate 23x while being in surface contact. In addition, the continuity of the magnetic circuit in the vertical direction is ensured by surface contact with the overhanging member 28x when the door 12 is closed. The connecting magnetic bodies 26z and 26x can also be magnetically integrated by tightening and fixing the magnetic properties of the PC permalloy within a range in which the magnetic characteristics of the PC permalloy do not deteriorate due to stress.

1 ... Magnetic shield target space (magnetic shield room)
DESCRIPTION OF SYMBOLS 2 ... Strip | belt-shaped magnetic plate (strip-shaped magnetic plate) 3 ... Shield housing | casing 4 ... Ring-band-shaped magnetic plate 5 ... Open type magnetic shield structure 6 ... Annular conductor plate 8 ... Magnetic sensor 9 ... Overlapping part 11 ... Door opening 12 ... Door (Door body)
14 ... Door frame 16 ... Expansion plate 17 ... Opening frame (magnetic flux detour)
20, 20x, 20y ... strip-shaped C-shaped magnetic plate 22 ... door magnetic plate 23, 23x, 23y ... strip-shaped magnetic plate 24 ... plate-shaped magnetic plate 26, 26x, 26y ... connecting magnetic body 27 ... angle member 28 ... projecting member 29 ... Covering member 30, 30x, 30y ... Strip C-shaped conductor plate 32 ... Conductor opening frame 36, 36x, 36y ... Connecting conductor 37 ... Angle member 38 ... Overhang member 39 ... Covering member Ax, Ay, Az ... Shaft C ... Long Center axis F ... Saddle surface d ... Spacing I ... Current L ... Coil M ... Disturbing magnetic field O ... Center point Px, Py, Pz ... Plane Wc ... Band width of ring-shaped magnetic plate Wm ... Band width of ring-shaped conductor plate

Claims (7)

A belt-like first C provided on each of a plurality of parallel planes intersecting a first direction axis passing through a magnetic shield target space with a door opening parallel to the door at a predetermined interval, and cut at the door opening while surrounding the space. A letter-shaped magnetic plate disposed on the door at a right angle to the band width surface of the first C-shaped magnetic plate along a line of intersection between a plurality of planes intersecting the first direction axis and the door closing the opening; A plurality of strip-shaped first I-shaped magnetic plates insulated from each other, and an L-shaped angle shape attached to both ends of each cut portion of the first C-shaped magnetic plate so as to face the first I -shaped magnetic plate And a door open magnetic shield structure comprising a pressing mechanism for bringing the first C-shaped magnetic plate and the first I-shaped magnetic plate into close contact with each other through the connecting magnetic body when the door opening is closed . 2. The magnetic shield structure according to claim 1, wherein the first C-shaped magnetic plate is nested in a plurality of parallel planes intersecting a second direction axis passing through the space parallel to the door at a predetermined interval, and A belt-like second C-shaped magnetic plate that is cut at the door opening while surrounding the space, and a second C-shaped magnetic plate on the door along the intersection line of the plurality of planes intersecting the second direction axis and the door, respectively. A plurality of strip-shaped second I-shaped magnetic plates that are arranged perpendicular to the band width surface of the first and separated from each other and insulated from the first C-shaped magnetic plate, and cut portions of each of the second C-shaped magnetic plates An L-shaped angle-shaped connecting magnetic body is attached to both ends of the door so as to face the second I -shaped magnetic plate, and the second C-shaped magnetic plate is interposed via the connecting magnetic body when the door opening is closed by the pressing mechanism. When the door with open made in close contact and a second 2I-shaped magnetic plate Type magnetic shield structure. 3. The magnetic shield structure according to claim 2 , wherein a ring-shaped magnetic plate surrounding each space is provided on a plurality of parallel planes intersecting at a predetermined interval with a third direction axis penetrating the space perpendicular to the door. An open type magnetic shield structure with a door in which a first C-shaped magnetic plate, a second C-shaped magnetic plate, and a ring-shaped magnetic plate are arranged in a nested manner. 4. The magnetic shield structure according to claim 3 , wherein a belt-like first C-shaped conductor plate that is cut at a door opening while surrounding the space is provided at intervals between a plurality of first C-shaped magnetic plates intersecting the first direction axis. , An open type magnetic shield structure with a door, in which a conductor opening frame is fixed around the inside of the opening, and both ends of the cut portions of the first C-shaped conductor plates are electrically joined to the conductor opening frame. 5. The magnetic shield structure according to claim 3 , wherein the second C-shaped conductor plate is a belt-shaped second C-shaped conductor plate that is cut at a door opening while enclosing the space between the plurality of second C-shaped magnetic plates intersecting the second direction axis. An open type magnetic shield structure with a door, in which a conductor opening frame is fixed around the inside of the opening, and both ends of the cut portions of the second C-shaped conductor plates are electrically joined to the conductor opening frame. 6. The magnetic shield structure according to claim 3 , wherein an open-type magnetic shield with a door is provided in which a ring-shaped conductor plate surrounding each of the spaces is provided at intervals between the plurality of ring-shaped magnetic plates intersecting the third direction axis. Construction. 7. The magnetic shield structure with a door according to claim 1 , wherein the C-shaped magnetic plate and the I-shaped magnetic plate are made of PC permalloy magnetic plates having the same width and thickness, respectively. .