JPH05275879A - Magnetic shielding structure - Google Patents
Magnetic shielding structureInfo
- Publication number
- JPH05275879A JPH05275879A JP6243291A JP6243291A JPH05275879A JP H05275879 A JPH05275879 A JP H05275879A JP 6243291 A JP6243291 A JP 6243291A JP 6243291 A JP6243291 A JP 6243291A JP H05275879 A JPH05275879 A JP H05275879A
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- Prior art keywords
- opening
- magnetic field
- ferromagnetic
- cylindrical
- space
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、例えば強磁性体を利用
した磁気シールド空間に開設された開口部からの磁気侵
入を防ぐ磁気シールド構造に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic shield structure for preventing magnetic intrusion from an opening formed in a magnetic shield space using, for example, a ferromagnetic material.
【０００２】[0002]
【従来の技術】強磁性体を用いたシールド構造では、例
えば強磁性体材料で円筒状のシールド体を構成した場合
には、磁場中にこのシールド体が保持されると、シール
ド体に沿って磁気誘導が生じ、結果的に磁場の方向を変
更させて、内部空間を磁気シールドするものである。こ
のような強磁性体材料を用いたシールド空間は、低磁場
環境での観測や、ノイズレス空間の実現等と、現在では
種々に応用されている。磁気シールド空間では、多くの
場合、内部に被測定物を出し入れするための開口部が必
要である。2. Description of the Related Art In a shield structure using a ferromagnetic material, for example, when a cylindrical shield body is made of a ferromagnetic material, when the shield body is held in a magnetic field, the shield body is guided along the shield body. Magnetic induction occurs, and as a result, the direction of the magnetic field is changed to magnetically shield the internal space. The shield space using such a ferromagnetic material is now being used in various applications such as observation in a low magnetic field environment and realization of a noiseless space. In many cases, the magnetic shield space needs an opening for inserting and removing the object to be measured.
【０００３】[0003]
【発明が解決しようとする課題】しかしながら、開口部
があると、ここから磁場が侵入し、内部に低磁場を作る
のが困難となる。このため開口部を開閉式にし、測定時
には閉じるとか開口部を小さくして磁場侵入を防ぐ方法
が取られてきた。しかし、低磁場空間を実現するには開
閉式の場合には、通常強磁性体を多層に用いてシールド
体壁を構成するので、その壁の厚さが大きく且つ開閉用
扉とシールド壁との間隙の磁気抵抗を小さくする必要が
あるため扉の構造が複雑となり、且つ扉の重量が大きい
ので開閉装置も特別なものとなる。従ってコストが高く
なる等の問題が生じていた。また、開口部を小さくする
と大きな被測定物の搬入ができなくなり大きなシールド
体は構成できない。However, if there is an opening, the magnetic field penetrates from here, making it difficult to create a low magnetic field inside. For this reason, a method has been adopted in which the opening is opened and closed, and during measurement, it is closed or the opening is made small to prevent the magnetic field from entering. However, in order to realize a low magnetic field space, in the case of the opening and closing type, since the shield body wall is usually formed by using ferromagnetic materials in multiple layers, the thickness of the wall is large and the opening and closing door and the shield wall are Since it is necessary to reduce the magnetic resistance of the gap, the structure of the door is complicated, and the weight of the door is large, so that the opening / closing device is also special. Therefore, there have been problems such as high cost. Further, if the opening is made small, a large object to be measured cannot be carried in, and a large shield cannot be constructed.
【０００４】一方、強磁性体による例えば円筒状のシー
ルド体では、横磁場より縦磁場の遮蔽能が良くないの
で、高い遮蔽能を得るために円筒を数層重ね、内層を外
層より短くする構造をとらなければならなかった。その
結果、強磁性体でも、最外層の円筒の長さが長くなり、
また使用可能な容積が大きければさらに長くなってコス
トが高くなるという問題点もあった。On the other hand, in a cylindrical shield made of a ferromagnetic material, for example, the longitudinal magnetic field shielding ability is poorer than the transverse magnetic field. Therefore, in order to obtain high shielding ability, several cylinders are stacked and the inner layer is made shorter than the outer layer. Had to take. As a result, even in ferromagnetic materials, the length of the outermost cylinder increases,
There is also a problem that if the usable volume is large, the volume becomes longer and the cost becomes higher.
【０００５】本発明の目的は、シールド空間の開口部か
らの磁場侵入を小さくし、且つ開閉が容易な扉を与え、
構造が簡単で、コストの低い磁気シールド構造を実現す
ることを目的とする。An object of the present invention is to provide a door which can reduce magnetic field penetration from the opening of the shielded space and can be easily opened and closed,
An object is to realize a magnetic shield structure having a simple structure and low cost.
【０００６】[0006]
【課題を解決するための手段】本発明に係る磁気シール
ド構造では、所定の空間を強磁性体で囲んだ開口部を有
するシールド空間において、前記シールド空間の開口部
に、該開口部と同方向の開口を有する強磁性体よりなる
筒状部材を、間隔を開けて同心多重状に配設したことを
特徴とするものである。尚、前記多重筒状部材の断面形
状は、前記シールド空間の開口部と同形状としたことを
特徴とするものであり、具体的に筒状強磁性体部材の断
面形状が、円形又は多角形としたものである。In a magnetic shield structure according to the present invention, in a shield space having an opening in which a predetermined space is surrounded by a ferromagnetic material, the opening of the shield space is in the same direction as the opening. The cylindrical members made of a ferromagnetic material having the above-mentioned openings are arranged in a concentric multiplex pattern with a space therebetween. The cross-sectional shape of the multiple cylindrical member is the same as that of the opening of the shield space. Specifically, the cross-sectional shape of the cylindrical ferromagnetic member is circular or polygonal. It is what
【０００７】[0007]
【作用】本発明では、強磁性体の筒状部材の間隙に侵入
する磁場の減衰量を計算する手法を解明し、この結果に
基づき本発明に至ったものであり、詳しくは、強磁性体
のシールド空間の開口部に、該開口部と同方向の開口を
有する強磁性体よりなる筒状部材を、間隔を開けて同心
多重状に配設したものであるため、強磁性体の筒状部材
による磁場の減衰を利用し、筒状部材を幾層も重ねるこ
とにより、より低い磁場の減衰を達成し、シールド空間
外からの磁場の侵入を防ぐものである。In the present invention, a method for calculating the attenuation amount of the magnetic field penetrating into the gap between the ferromagnetic cylindrical members has been clarified, and the present invention has been completed based on this result. Since a cylindrical member made of a ferromagnetic material having an opening in the same direction as the opening is arranged in a concentric multiplex pattern at an opening of the shield space of By utilizing the attenuation of the magnetic field by the member and stacking a number of layers of cylindrical members, a lower attenuation of the magnetic field is achieved and the invasion of the magnetic field from outside the shield space is prevented.
【０００８】次に、強磁性体の筒状部材に侵入する磁場
の減衰量の計算を説明する。先ず、単独強磁性体製円筒
体内部での磁場侵入は次の２式(1) (2) に従う。Next, the calculation of the attenuation amount of the magnetic field penetrating into the ferromagnetic cylindrical member will be described. First, the magnetic field penetration inside the single ferromagnetic cylinder follows the following two equations (1) and (2).
【０００９】[0009]
【数１】 [Equation 1]
【数２】 [Equation 2]
【００１０】ここで、式(1) は外部磁場が円筒体軸と直
角方向に印加された場合で、式(2)は外部磁場が円筒体
軸と平行方向に印加された場合である。尚、Ｒ1 は単独
強磁性体製円筒体の半径、ｚは開口部からの距離、Ｈ
a ，Ｈt は磁場の強さである。この２式(1) (2) から、
磁場侵入は外部磁場が円筒体軸方向に印加された場合に
大きくなることが判る。例えば、磁場侵入量を１０-5ま
で小さくしようとすると、開口部から半径の５倍程度内
部に入る必要がある。言い換えれば、開口部の長さは半
径の５倍を必要とすることである。Here, the equation (1) is the case where the external magnetic field is applied in the direction perpendicular to the cylinder axis, and the equation (2) is the case where the external magnetic field is applied in the direction parallel to the cylinder axis. Note that R 1 is the radius of the single ferromagnetic cylinder, z is the distance from the opening, and H is
a and Ht are magnetic field strengths. From these two formulas (1) and (2),
It can be seen that the magnetic field penetration increases when an external magnetic field is applied in the axial direction of the cylinder. For example, in order to reduce the magnetic field penetration amount to 10 −5 , it is necessary to enter the inside from the opening by about 5 times the radius. In other words, the length of the opening requires 5 times the radius.
【００１１】さて、図１は強磁性体製円筒を同心円状に
配置した多重円筒体のモデルを示す説明図である。図２
は外側円筒体と内側円筒体との間隙に侵入する磁場の減
衰量の計算結果を示す線図である。図１に示す通り、こ
の円筒体群の開口端からこれら円筒体群の間隙に磁場が
侵入して行き、長さｚだけ入った内部での磁場強度は図
２で示される定数Ｋにより表わされる次の式(3) とな
る。FIG. 1 is an explanatory view showing a model of a multi-cylinder body in which ferromagnetic cylinders are concentrically arranged. Figure 2
FIG. 6 is a diagram showing a calculation result of the attenuation amount of a magnetic field penetrating the gap between the outer cylinder and the inner cylinder. As shown in FIG. 1, the magnetic field penetrates into the gaps between the cylinders from the open ends of the cylinders, and the magnetic field strength inside the length z is represented by the constant K shown in FIG. It becomes the following formula (3).
【００１２】[0012]
【数３】 [Equation 3]
【００１３】尚、ここで式(3) のｄp はこの間隙の大き
さであり、最内部円筒体の内部磁場については、その半
径を表わすものとする。また、これら強磁性体−強磁性
体で構成される間隙では図２からその間隙の磁場の減衰
はｄn ＜ 0.5Ｒn の時、おおよそ次の式(4) となる。Here, d p in the equation (3) is the size of this gap, and the radius of the internal magnetic field of the innermost cylindrical body is represented. Further, in the gap composed of these ferromagnetic bodies-ferromagnetic bodies, from FIG. 2, when the attenuation of the magnetic field in the gap is d n <0.5R n , the following formula (4) is approximately obtained.
【００１４】[0014]
【数４】 [Equation 4]
【００１５】また、強磁性体最内部円筒の内部磁場の減
衰は、おおよそ次の式(5) (6) が求められる。For the attenuation of the internal magnetic field of the innermost cylinder of the ferromagnetic material, the following equations (5) and (6) can be obtained.
【００１６】[0016]
【数５】 [Equation 5]
【数６】 [Equation 6]
【００１７】これらの間隙に侵入する磁場が、その出口
即ちｚ＝Ｌにおいて等しくなるように強磁性体製円筒体
の径を設計することが侵入磁場を最小にする上で最適と
なる。従って、次の式(7) の関係を満たすように間隙を
定めればよい。Designing the diameters of the ferromagnetic cylinders so that the magnetic field penetrating these gaps is equal at their exits, ie z = L, is optimal for minimizing the penetrating magnetic field. Therefore, the gap may be set so as to satisfy the following expression (7).
【００１８】[0018]
【数７】 [Equation 7]
【００１９】更に、円筒の厚さを無視すると、次の式
(8) の関係が得られる。Further, ignoring the thickness of the cylinder, the following equation
The relationship of (8) is obtained.
【００２０】[0020]
【数８】 [Equation 8]
【００２１】また、この時の円筒体の間隙ｄp 及び半径
Ｒp は次の式(9) (10)で示される。The gap d p and the radius R p of the cylindrical body at this time are expressed by the following equations (9) and (10).
【００２２】[0022]
【数９】 [Equation 9]
【数１０】 [Equation 10]
【００２３】ところで、長さＬでの出口磁場は、次の式
(11)となり、これが内側円筒体がない単独円筒体のみの
場合の次の式(12)に対して著しく改善されることが判
る。By the way, the exit magnetic field at the length L is expressed by the following equation:
It becomes (11), and it can be seen that this is remarkably improved with respect to the following formula (12) in the case of only a single cylinder without an inner cylinder.
【００２４】[0024]
【数１１】 [Equation 11]
【数１２】 [Equation 12]
【００２５】以上の式の比較から円筒体の長さが、K1/
(K1+K2+…+Kn)で、同一磁場減衰量が得られることが解
る。さて具体的には、強磁性体製円筒体をｎ組用いた
時、長さＬでの磁場の強さは、次の式(13)となり、これ
が内側円筒体を配設していない単独円筒体のみに対し
て、円筒体の長さが1/(1.36n-0.31)で同一磁場減衰量が
得られることが解る。From the comparison of the above equations, the length of the cylinder is K 1 /
It can be seen that the same magnetic field attenuation can be obtained by (K 1 + K 2 +… + K n ). Now, concretely, when n sets of ferromagnetic cylinders are used, the strength of the magnetic field at the length L is given by the following formula (13), which is a single cylinder without an inner cylinder. It can be seen that the same magnetic field attenuation can be obtained when the length of the cylinder is 1 / (1.36n-0.31) only for the body.
【００２６】[0026]
【数１３】 [Equation 13]
【００２７】この時の、各々の円筒の半径Ｒp 、間隙ｄ
p は次の式(14)(15)で示される。At this time, the radius R p of each cylinder and the gap d
p is expressed by the following equations (14) and (15).
【００２８】[0028]
【数１４】 [Equation 14]
【数１５】 [Equation 15]
【００２９】以上のように、強磁性体製円筒体の数
（ｎ）をふやせば磁場減衰量は大きくできるが、間隙が
小さくなるので、自ずと限界が生ずることが判る。ま
た、強磁性体は微弱磁場ではその透磁率が著しく減少
し、磁場減衰量に限界が生ずることが判る。この場合、
１０-5程度の減衰が実用的限界である。これらの点を考
慮して強磁性体製円筒体の数（ｎ）の値が決められる。As described above, if the number (n) of ferromagnetic cylinders is increased, the magnetic field attenuation amount can be increased, but the gap becomes smaller, so it is understood that a limit naturally occurs. Further, it is understood that the magnetic permeability of the ferromagnetic material is remarkably reduced in a weak magnetic field, and the magnetic field attenuation amount is limited. in this case,
Attenuation of about 10 -5 is a practical limit. Considering these points, the value of the number (n) of ferromagnetic cylinders is determined.
【００３０】尚、ここでは同心円筒状の構造について述
べたが、類似の多角形断面を有する筒状構造についても
同様なことができることは言うまでもない。また、幾層
にも重ね合わせる筒状体は、間隙をもって配されれば良
く、必ずしも同心上に配する必要はないが、間隙の幅が
最も大きい箇所でシールド特性が定まるため、同心上が
最も効率が良い。Although the concentric cylindrical structure has been described here, it goes without saying that the same can be applied to a cylindrical structure having a similar polygonal cross section. In addition, the cylindrical bodies that are stacked in multiple layers need only be arranged with a gap, and do not necessarily have to be arranged concentrically, but since the shield characteristics are determined at the location where the width of the gap is largest, concentricity is the most important. Good efficiency.
【００３１】[0031]
【実施例】（実施例１）図３は本発明の一実施例の構成
を示す説明図である。図に示すように、円形断面部分の
内径１ｍ，長さ2.5 ｍの円筒状強磁性体（パーマロイ）
(31)の開口部に長さ70cm，厚さ５mmの強磁性体（パーマ
ロイ）で作られた直径がそれぞれ90cm，66cm，42cmの円
筒を同心上にはめ込んだ多重筒状部材(32)を設けた。こ
れらの多重筒状部材の筒は支持枠（図示せず）で支えら
れ、搬入する機器などを出し入れするため取り外せるよ
うに設計されている。この内部の磁場の強さを測定した
ところ、円筒状強磁性体(31)内部のＡ点の磁場は外部磁
場に対してそれぞれ10-5倍になった。一方、多重筒状部
材(32)を取り除いて測定したところ、同じく円筒状強磁
性体(31)内部のＡ点の磁場は外部磁場に対してそれぞれ
10-1倍であった。このことから本発明により強磁性体円
筒の開口部に侵入する磁場が著しく小さく出来ることが
わかる。(Embodiment 1) FIG. 3 is an explanatory diagram showing the construction of an embodiment of the present invention. As shown in the figure, a cylindrical ferromagnetic material (permalloy) with an inner diameter of 1 m and a length of 2.5 m in a circular cross section
Provided in the opening of (31) is a multi-cylindrical member (32) in which cylinders made of a ferromagnetic material (permalloy) having a length of 70 cm and a thickness of 5 mm and having diameters of 90 cm, 66 cm and 42 cm are concentrically fitted. It was The tubes of these multiple tubular members are supported by a support frame (not shown), and are designed to be detachable for taking in and out a device to be carried in and out. When the strength of the internal magnetic field was measured, the magnetic field at point A inside the cylindrical ferromagnetic body (31) was 10 −5 times that of the external magnetic field. On the other hand, when the multi-cylindrical member (32) was removed and measured, the magnetic field at point A inside the cylindrical ferromagnetic body (31) was also different from the external magnetic field.
It was 10 -1 times. From this, it can be seen that the magnetic field penetrating the opening of the ferromagnetic cylinder can be significantly reduced by the present invention.
【００３２】（実施例２）図４は本発明の別の実施例の
構成を示す説明図である。図に示すように、シールドル
ーム(41)の開口部（横幅１ｍ，高さ 1.5ｍ）に長さ80cm
であり、これらの厚さが５mmの強磁性体（パーマロイ）
で作られた横幅が各々 100cm、74cm、47cm、21cmで高さ
が各々 150cm、 111cm、70cm、32cmの断面が四角い筒を
同心上にはめ込んだ多重筒状部材(42)を設けた。これら
の多重筒状部材(42)は、最外部の筒をシールドルーム(4
1)壁に接続し、その内側の筒は支持枠（図示せず）で支
えられ、シールドルーム(41)へ搬入する機器などを出し
入れするため、開閉するように設計されている。この内
部の磁場の強さを測定したところ、シールドルーム(41)
内部のＡ点の磁場は外部磁場に対して10-3倍になった。(Embodiment 2) FIG. 4 is an explanatory view showing the constitution of another embodiment of the present invention. As shown in the figure, the opening of the shield room (41) (width 1m, height 1.5m) is 80cm long.
And a ferromagnetic material (permalloy) having a thickness of 5 mm
A multi-cylinder member (42) was made by concentrically fitting the cylinders with 100 cm, 74 cm, 47 cm, and 21 cm in width and 150 cm, 111 cm, 70 cm, and 32 cm in height and square cross sections. These multiple tubular members (42) connect the outermost tube to the shield room (4
1) Connected to a wall, the inner tube is supported by a support frame (not shown), and is designed to be opened and closed in order to take in and out equipment and the like to be carried in and out of the shield room (41). When the strength of the magnetic field inside this was measured, the shield room (41)
The internal magnetic field at point A was 10 -3 times that of the external magnetic field.
【００３３】一方、構造(42)を取り外して測定したとこ
ろ、同じくシールドルーム(41)内部のＡ点の磁場は外部
磁場に対してそれぞれ10-1倍であった。このことから本
発明により超電導体製円筒体内に侵入する磁場が著しく
小さく出来ることがわかる。On the other hand, when the structure (42) was detached and measured, the magnetic field at point A inside the shield room (41) was 10 -1 times the external magnetic field. From this, it is understood that the magnetic field penetrating into the superconductor cylinder can be made extremely small by the present invention.
【００３４】[0034]
【発明の効果】以上説明したように、強磁性体のシール
ド空間の開口部に、該開口部と同方向の開口を有する強
磁性体よりなる筒状部材を、間隔を開けて同心多重状に
配設したものであるため、強磁性体の筒状部材による磁
場の減衰を利用し、筒状部材を幾層も重ねることによ
り、より低い磁場の減衰を達成し、シールド空間外から
の磁場の侵入を防ぐことができる。As described above, a cylindrical member made of a ferromagnetic material having an opening in the same direction as the opening is provided in the opening of the shield space of the ferromagnetic material in a concentric multiplex shape with a space. Since it is arranged, the attenuation of the magnetic field by the ferromagnetic cylindrical member is utilized, and a lower magnetic field attenuation is achieved by stacking multiple layers of the cylindrical member, and the magnetic field from the outside of the shield space is reduced. Intrusion can be prevented.
【００３５】このため、比較的容易に低コストで低磁場
空間への開口部が実現でき、微小な磁気現象を観測する
ことができる。機材の搬入可能な空間が作れる。これら
科学技術上、及び医療上有用な用途が多く工業的価値も
大である。Therefore, the opening to the low magnetic field space can be realized relatively easily and at low cost, and a minute magnetic phenomenon can be observed. You can create a space where you can carry in equipment. These have many industrially useful applications in terms of science and technology and have great industrial value.
【図１】図１は強磁性体製円筒体を同心円状に配置した
多重円筒体のモデルを示す説明図である。FIG. 1 is an explanatory view showing a model of a multi-cylinder in which ferromagnetic cylinders are concentrically arranged.
【図２】外側円筒体と内側円筒体との間隙に侵入する磁
場の減衰量の計算結果を示す線図である。FIG. 2 is a diagram showing a calculation result of an attenuation amount of a magnetic field entering a gap between an outer cylinder and an inner cylinder.
【図３】本発明の一実施例の構成を示す説明図である。FIG. 3 is an explanatory diagram showing a configuration of an exemplary embodiment of the present invention.
【図４】本発明の別の実施例の構成を示す説明図であ
る。FIG. 4 is an explanatory diagram showing the configuration of another embodiment of the present invention.
３１ 円筒状強磁性体 ４１ シールドルーム ３２，４２ 多重筒状部材 31 Cylindrical Ferromagnetic Material 41 Shield Room 32, 42 Multiple Cylindrical Members
Claims (1)
有するシールド空間において、 前記シールド空間の開口部に、該開口部と同方向の開口
を有する強磁性体よりなる筒状部材を、間隔を開けて同
心多重状に配設したことを特徴とする磁気シールド構
造。1. A shield space having an opening in which a predetermined space is surrounded by a ferromagnetic material, wherein a cylindrical member made of a ferromagnetic material having an opening in the same direction as the opening is provided in the opening of the shield space. A magnetic shield structure characterized in that the magnetic shield structure is arranged in a concentric multiple state with an interval.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6243291A JPH05275879A (en) | 1991-03-05 | 1991-03-05 | Magnetic shielding structure |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6243291A JPH05275879A (en) | 1991-03-05 | 1991-03-05 | Magnetic shielding structure |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05275879A true JPH05275879A (en) | 1993-10-22 |
Family
ID=13200017
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6243291A Pending JPH05275879A (en) | 1991-03-05 | 1991-03-05 | Magnetic shielding structure |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05275879A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008218729A (en) * | 2007-03-05 | 2008-09-18 | Toyohashi Univ Of Technology | Magnetic shield box for metal detector |
| JP2012227515A (en) * | 2011-04-04 | 2012-11-15 | Seiko Epson Corp | Magnetic shield, program, and selection method |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58145199A (en) * | 1982-02-23 | 1983-08-29 | 富士通株式会社 | Magnetic shielding enclosure by magnetic fluid |
| JPS6365297B2 (en) * | 1978-11-17 | 1988-12-15 |
-
1991
- 1991-03-05 JP JP6243291A patent/JPH05275879A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6365297B2 (en) * | 1978-11-17 | 1988-12-15 | ||
| JPS58145199A (en) * | 1982-02-23 | 1983-08-29 | 富士通株式会社 | Magnetic shielding enclosure by magnetic fluid |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008218729A (en) * | 2007-03-05 | 2008-09-18 | Toyohashi Univ Of Technology | Magnetic shield box for metal detector |
| JP2012227515A (en) * | 2011-04-04 | 2012-11-15 | Seiko Epson Corp | Magnetic shield, program, and selection method |
| US9612295B2 (en) | 2011-04-04 | 2017-04-04 | Seiko Epson Corporation | Magnetic shield, program, and selection method |
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