JP6599258B2 - Shaking type open magnetic shield structure - Google Patents
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Description
本発明はシェイキング式の開放型磁気シールド構造に関し，とくに磁気シェイキングを利用して遮蔽性能を向上させた開放型磁気シールド構造に関する。 The present invention relates to an open type magnetic shield structure of a shaking type, and more particularly to an open type magnetic shield structure having improved shielding performance using magnetic shaking.
半導体製造施設等で用いる電子顕微鏡，ＥＢ露光装置，ＥＢステッパー等の電子ビーム応用装置は，微弱な磁気変動でも電子ビームの軌道が変化して製品の品質が劣化するため，外乱磁場変動を１００ｎＴ（１ｍＧ）以下に制御された磁気シールドルーム（磁気シールド空間）に設置することが求められる。従来の一般的な磁気シールド空間はＰＣパーマロイ等の透磁率の高い磁性体で床，壁，天井の全体を隙間なく覆う構造（密閉型磁気シールド構造）であるが，材料サイズの制約等から接合部が多くなり，接合部からの外乱磁場の浸入に伴う性能劣化が問題となっていた。これに対し，図１４に示すように，簾状又はルーバー状に並べた帯状磁性板（短冊形磁性板）を用いた磁気シールド構造（開放型磁気シールド構造）５が開発されている（特許文献１参照）。 Electron beam application devices such as electron microscopes, EB exposure devices, and EB steppers used in semiconductor manufacturing facilities, etc., even with weak magnetic fluctuations, change the trajectory of the electron beam and degrade the product quality. It is required to be installed in a magnetic shield room (magnetic shield space) controlled to 1 mG or less. The conventional general magnetic shield space is a structure (sealed magnetic shield structure) that covers the entire floor, wall, and ceiling with a magnetic material with high permeability such as PC permalloy (sealed magnetic shield structure). The number of parts increased, and the performance degradation due to the penetration of the disturbance magnetic field from the joints was a problem. On the other hand, as shown in FIG. 14, a magnetic shield structure (open magnetic shield structure) 5 using strip-shaped magnetic plates (strip-shaped magnetic plates) arranged in a bowl shape or a louver shape has been developed (Patent Literature). 1).
開放型磁気シールド構造５は，例えば幅５０ｍｍ程度の複数の帯状磁性板２を長さ方向中心軸Ｃが同一面Ｆ上に平行に並ぶように所要の板厚方向間隔ｄで積み重ねてシールド簾体３とし（図１４（Ａ）参照），複数のシールド簾体３ａ，３ｂ，３ｃ，３ｄを対応する端縁の接合部９の重ね合わせにより磁気的に接合して環状に閉じた帯状磁性板（以下，環帯状磁性板という）１０を形成し，複数の環帯状磁性板１０によって磁気シールド対象空間を囲んだものである（図１４（Ｂ）参照）。環帯状磁性板１０の適切な間隔ｄを設計することにより，磁気シールド対象空間に開放性（透視性，透光性，放熱性）を与えつつ，環帯状磁性板１０（磁性体回路）に磁束を集中させて間隔ｄからの磁束の侵入及び漏洩（性能劣化）を小さく抑えることができる。また，接合部９で磁気的連続性が確保しやすいことから，性能劣化が少なく，所期性能を発揮することが容易な構造となっている。更に，安全率を小さく抑え，従来の密閉型磁気シールド構造に比して使用する材料を減らすことができるため，コストダウンにも繋がる利点を有している。 The open type magnetic shield structure 5 includes a plurality of strip-like magnetic plates 2 having a width of about 50 mm, for example, which are stacked at a required thickness direction interval d so that the longitudinal central axes C are arranged in parallel on the same plane F. 3 (see FIG. 14 (A)), a plurality of shield housings 3a, 3b, 3c, 3d are magnetically joined by overlapping the corresponding joints 9 at the end edges, and a belt-like magnetic plate (annularly closed) (Hereinafter, referred to as an annular belt-shaped magnetic plate) 10 is formed, and a magnetic shield target space is surrounded by a plurality of annular belt-shaped magnetic plates 10 (see FIG. 14B). By designing an appropriate distance d of the ring-shaped magnetic plate 10, magnetic flux is applied to the ring-shaped magnetic plate 10 (magnetic circuit) while providing openness (permeability, translucency, heat dissipation) to the magnetic shield target space. , And the magnetic flux intrusion and leakage (performance degradation) from the interval d can be kept small. In addition, since the magnetic continuity can be easily secured at the joint 9, the performance is less deteriorated and the desired performance can be easily achieved. Furthermore, since the safety factor can be reduced and the amount of material used can be reduced compared to the conventional sealed magnetic shield structure, there is an advantage that leads to cost reduction.
また開放型磁気シールド構造５は，外乱磁場の周波数が高くなると環帯状磁性板１０の断面に流れる渦電流によって磁気シールド性能が劣化しうるが，環帯状磁性板１０（磁性体回路）に銅板やアルミニウム板等の環帯状導体（導体回路）を付加して導体シールド効果を重畳することにより，２００Ｈｚ程度までの外乱磁場（交流磁場）においても直流磁場と同等以上の遮蔽性能を発揮することができる（特許文献２参照）。すなわち，環帯状磁性板で構成された開放型磁気シールド構造５，或いは必要に応じて導体回路を付加した開放型磁気シールド構造５により磁気シールド空間を構築すれば，環境磁気ノイズ（外乱磁場変動）を効率的に１００ｎＴ以下にまで遮断し，電子ビーム応用装置等を設置するに相応しい磁気環境（磁気シールド空間）を提供することができる。 In the open type magnetic shield structure 5, the magnetic shield performance can be deteriorated by the eddy current flowing in the cross section of the ring-shaped magnetic plate 10 when the frequency of the disturbance magnetic field is increased. By adding a ring-shaped conductor (conductor circuit) such as an aluminum plate and superimposing the conductor shielding effect, even a disturbance magnetic field (AC magnetic field) up to about 200 Hz can exhibit shielding performance equivalent to or better than a DC magnetic field. (See Patent Document 2). That is, if the magnetic shield space is constructed by the open type magnetic shield structure 5 constituted by an annular magnetic plate 5 or the open type magnetic shield structure 5 to which a conductor circuit is added if necessary, environmental magnetic noise (disturbance magnetic field fluctuation) Can be effectively cut down to 100 nT or less, and a magnetic environment (magnetic shield space) suitable for installing an electron beam application apparatus or the like can be provided.
他方，医療施設や研究施設で用いるＳＱＵＩＤ（超電導量子干渉素子）応用装置は，脳や心臓の活動に伴い発生する超微弱な脳磁波，心磁波等の磁場を測定するため，設置空間を１ｎＴ以下の磁気環境に制御することが求められる。このような超高度な磁気環境を得る手段として磁気シェイキングが提案されている（特許文献３，４，非特許文献１参照）。磁気シェイキングとは，周期的に変動する磁場（シェイキング磁場）を磁性体に印加して磁性体内部で磁束を揺らすことにより磁性体の磁気特性（実効的な透磁率）を向上させる手法である。例えば特許文献３は，比較的低コストで製造できる厚さ２０μｍ以上５００μｍ以下のフィルム（又はリボン）状のアモルファス磁性薄帯材で密閉型磁気シールド構造を構成し，磁気シェイキングによってパーマロイ並みの性能を得たことを報告している。 On the other hand, SQUID (Superconducting Quantum Interference Device) application devices used in medical facilities and research facilities measure the magnetic field such as ultra-weak brain magnetic waves and magneto-magnetic waves generated by the activity of the brain and heart. It is required to control the magnetic environment. Magnetic shaking has been proposed as means for obtaining such an ultra-high magnetic environment (see Patent Documents 3 and 4, Non-Patent Document 1). Magnetic shaking is a technique for improving the magnetic properties (effective permeability) of a magnetic material by applying a periodically varying magnetic field (shaking magnetic field) to the magnetic material to sway the magnetic flux inside the magnetic material. For example, in Patent Document 3, a sealed magnetic shield structure is constituted by an amorphous magnetic ribbon material in the form of a film (or ribbon) having a thickness of 20 μm or more and 500 μm or less which can be manufactured at a relatively low cost. It is reported that I got it.
磁気シェイキングでは，磁性体内部で磁束を揺らす（シェイキングする）ため，磁性体の磁化容易方向の軸の周りにほぼ垂直にシェイキングコイルを巻き，遮蔽したい環境磁気ノイズの周波数成分ｆｎよりも高い周波数ｆの電流（シェイキング電流）を印加してシェイキング磁場を発生させる。例えば特許文献４の開示する密閉型磁気シールド用の磁気シールド部材４０は，図１５に示すように，基材４１の表面上にリボン状の８本のアモルファス磁性薄帯４２ａを長手方向が縦方向で平行となるように所定間隙で配列し，その表面上にリボン状の８本のアモルファス磁性薄帯４２ｂを長手方向が横方向で平行となるように所定間隙で配列し，井桁配置の磁性薄帯４２ａ，４２ｂの所定間隙に表裏を縫うようにシェイキングコイル４３を巻き付ける。図示例のコイル４３は，入力端子４４と出力端子４５との間を１６の部分に分け，図１５（Ｂ）に示すように奇数の部分で表面を通過させると共に偶数の部分で裏面を通過させることにより，磁性薄帯４２ａ，４２ｂの何れの長手方向に対してもほぼ垂直方向に巻き付けられている。 In magnetic shaking, since the magnetic flux is swayed (shaked) inside the magnetic body, a shaking coil is wound almost perpendicularly around the axis of the magnetization direction of the magnetic body, and the frequency f higher than the frequency component fn of the environmental magnetic noise to be shielded. Is applied (shaking current) to generate a shaking magnetic field. For example, as shown in FIG. 15, a magnetic shield member 40 for a sealed magnetic shield disclosed in Patent Document 4 has eight ribbon-like amorphous magnetic ribbons 42a on the surface of a base material 41 in the longitudinal direction. Are arranged with a predetermined gap so as to be parallel with each other, and eight ribbon-like amorphous magnetic ribbons 42b are arranged with a predetermined gap so that the longitudinal direction thereof is parallel with the lateral direction on the surface thereof. The shaking coil 43 is wound so as to sew the front and back in a predetermined gap between the bands 42a and 42b. In the illustrated example, the coil 43 is divided into 16 portions between the input terminal 44 and the output terminal 45, and as shown in FIG. 15 (B), the odd-numbered portion passes the surface and the even-numbered portion passes the back surface. Thus, the magnetic ribbons 42a and 42b are wound in a substantially vertical direction with respect to any longitudinal direction.
しかし，従来の磁気シェイキングには，磁性体内部をシェイキングするための印加磁場（シェイキング磁場）が磁気シールド空間へ漏洩してしまう問題点がある。例えば図１５の磁気シールド部材４０において，シェイキングコイル４３が表面及び裏面の両側に隣接平行している部分ではコイル外側の磁場が打ち消されるので磁気シールド空間への漏洩をある程度抑制できるが，シェイキングコイル４３が表面又は裏面の方側のみに配置される周縁部分ではコイル外側の磁場（シェイキングノイズ）が磁気シールド空間に漏洩する。また，シェイキング効果を高めるためには磁性体の内部を均等にシェイキングすることが望ましいにも拘わらず，図１５の磁気シールド部材４０では，磁性薄帯４２ａ，４２ｂにそれぞれ長手方向のシェイキング磁場と他方の長手方向と交差する向きのシェイキング磁場とが同時に印加されるので，各磁性薄帯４２ａ，４２ｂの内部が均等にシェイキングされない問題点もある。 However, the conventional magnetic shaking has a problem that an applied magnetic field (shaking magnetic field) for shaking the inside of the magnetic material leaks to the magnetic shield space. For example, in the magnetic shield member 40 of FIG. 15, the magnetic field outside the coil is canceled at the portion where the shaking coil 43 is adjacent and parallel on both sides of the front and back surfaces, so that leakage to the magnetic shield space can be suppressed to some extent. In the peripheral portion where only the front side or the back side is arranged, the magnetic field outside the coil (shaking noise) leaks into the magnetic shield space. Further, in order to enhance the shaking effect, it is desirable to shake the inside of the magnetic material evenly. However, in the magnetic shield member 40 shown in FIG. Since the shaking magnetic field in the direction intersecting with the longitudinal direction of the magnetic ribbons is simultaneously applied, there is a problem that the insides of the magnetic ribbons 42a and 42b are not shaken evenly.
シェイキングノイズの漏洩を防止するため，例えば非特許文献１は，シェイキングコイルを巻き付けたアモルファス層の内側をアルミニウム層で被覆し，更にアルミニウム層の内側を磁気シェイキングのないアモルファス層で被覆する３層構造を提案している。ただし，このような３層構造の対策によっても磁気シールド空間の内壁付近において１０ｎＴを超えるシェイキングノイズが計測されている。また，３層構造のようなノイズ対策は，磁気シールドの施工コストの高騰に繋がる問題点もある。１ｎＴ以下の磁気シールド空間を磁気シェイキングによって実現するためには，磁性体内部を均等にシェイキングすると共に，シェイキングノイズを低減することが必要である。 In order to prevent leakage of shaking noise, for example, Non-Patent Document 1 discloses a three-layer structure in which an amorphous layer around which a shaking coil is wound is covered with an aluminum layer, and further, the inner side of the aluminum layer is covered with an amorphous layer without magnetic shaking. Has proposed. However, even with such a three-layer structure measure, shaking noise exceeding 10 nT is measured near the inner wall of the magnetic shield space. In addition, noise countermeasures such as a three-layer structure have a problem that leads to an increase in the construction cost of the magnetic shield. In order to realize a magnetic shield space of 1 nT or less by magnetic shaking, it is necessary to shake the inside of the magnetic material evenly and reduce shaking noise.
そこで本発明の目的は，シェイキングノイズの漏洩を小さく抑えることができるシェイキング式の開放型磁気シールド構造を提供することにある。 SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a shaking type open type magnetic shield structure capable of suppressing leakage of shaking noise to a small level.
図１の実施例を参照するに，本発明によるシェイキング式の開放型磁気シールド構造は，磁気シールド対象空間１を貫く第１方向軸Ａｚと所定間隔ｄｚで交差する複数段の平行な平面Ｐｚ１，Ｐｚ２，……上にそれぞれ対象空間１を所定帯幅Ｗで囲むように設けた環帯状磁性板１０，環帯状磁性板１０の各段にそれぞれ環状軸に沿って所定ピッチＴで巻き付けた導線コイル２０，環帯状磁性板１０の各段の間隔ｄｚにそれぞれ環帯状磁性板１０と実質上同径で平行に設けた環状導体５０，導線コイル２０に所定周波数のシェイキング電流Ｉ１を印加するコイル駆動装置３０，及び環状導体５０にキャンセル電流Ｉ２を印加する導体駆動装置６０を備え，導線コイル２０内側の発生磁場により環帯状磁性板１０を磁気シェイキングすると共に導線コイル２０外側の漏洩磁場を環状導体５０の発生する磁場により打ち消してなるものである。 Referring to the embodiment of FIG. 1, a shaking type open magnetic shield structure according to the present invention includes a plurality of parallel planes Pz1, intersecting a first direction axis Az penetrating the magnetic shield target space 1 at a predetermined interval dz. Pz2,..., A conductive coil wound around the annular axis at a predetermined pitch T around each stage of the annular belt-like magnetic plate 10 and the annular belt-like magnetic plate 10 provided so as to surround the target space 1 with a prescribed belt width W, respectively. 20, a coil driving device for applying a shaking current I1 having a predetermined frequency to the annular conductor 50 and the conductive wire coil 20 provided in parallel with the annular belt-like magnetic plate 10 at intervals dz of the respective steps of the annular belt-like magnetic plate 10 30 and a conductor driving device 60 that applies a canceling current I2 to the annular conductor 50, and magnetically shakes and guides the ring-shaped magnetic plate 10 by a magnetic field generated inside the conductor coil 20. The coil 20 outside the leakage magnetic field is made to cancel the magnetic field generated in the annular conductor 50.
好ましい実施例では，図１（Ｂ）及び（Ｃ）に示すように，導体駆動装置６０が環状導体５０に印加するキャンセル電流の電流値を，導線コイル２０外側の漏洩磁場が最小となるように段毎に独立に設定する。望ましくは，環帯状磁性板１０の各段の導線コイル２０の所定ピッチＴを導線コイル２０外側の漏洩磁場が最小となるように設定する。 In the preferred embodiment, as shown in FIGS. 1B and 1C, the current value of the cancel current applied by the conductor driving device 60 to the annular conductor 50 is set so that the leakage magnetic field outside the conductor coil 20 is minimized. Set independently for each stage. Desirably, the predetermined pitch T of the conductive coil 20 at each stage of the ring-shaped magnetic plate 10 is set so that the leakage magnetic field outside the conductive coil 20 is minimized.
更に好ましい実施例では，図１に示すように，導線コイル２０及び環状導体５０の各段に平行配置の入出力ライン２０ａ，２０ｂ及び５０ａ，５０ｂを含め，入出力ライン２０ａ，２０ｂ及び５０ａ，５０ｂの漏洩磁場を逆向きの入出力電流により打ち消す。必要に応じて，図１３（Ｇ）及び（Ｈ）に示すように，導線コイル２０及び環状導体５０の各段の入出力ライン２０ａ，２０ｂ及び５０ａ，５０ｂを収容するスリット２３付き磁気シールド筒体２２を設けることができる。 In a more preferred embodiment, as shown in FIG. 1, input / output lines 20a, 20b and 50a, 50b including input / output lines 20a, 20b and 50a, 50b arranged in parallel at each stage of the conductor coil 20 and the annular conductor 50 are provided. The leakage magnetic field is canceled by the reverse input / output current. If necessary, as shown in FIGS. 13G and 13H, a magnetic shield cylinder with a slit 23 for accommodating the input / output lines 20a, 20b and 50a, 50b of each stage of the conductor coil 20 and the annular conductor 50 is provided. 22 can be provided.
本発明によるシェイキング式の開放型磁気シールド構造は，磁気シールド対象空間１を貫く第１方向軸Ａｚと所定間隔ｄｚで交差する複数段の平行な平面Ｐｚ１，Ｐｚ２，……上にそれぞれ対象空間１を所定帯幅Ｗで囲むように環帯状磁性板１０を設け，環帯状磁性板１０の各段にそれぞれ環状軸に沿って導線コイル２０を所定ピッチＴで巻き付け，環帯状磁性板１０の各段の間隔ｄｚにそれぞれ環帯状磁性板１０と実質上同径で平行に環状導体５０を設け，コイル駆動装置３０によって導線コイル２０に所定周波数のシェイキング電流Ｉ１を印加して発生させた導線コイル２０内側の磁場により環帯状磁性板１０を磁気シェイキングすると共に，導体駆動装置６０によって環状導体５０にキャンセル電流Ｉ２を印加して発生させたキャンセル磁場により導線コイル２０外側の漏洩磁場を打ち消すので，次の有利な効果を奏する。 The shaking type open type magnetic shield structure according to the present invention includes a target space 1 on a plurality of parallel planes Pz1, Pz2,... Intersecting a first direction axis Az penetrating the magnetic shield target space 1 at a predetermined interval dz. Are provided with a predetermined band width W, and a coil 20 is wound around each stage of the ring-shaped magnetic plate 10 along the annular axis at a predetermined pitch T. The inside of the conductor coil 20 generated by applying the shaking current I1 having a predetermined frequency to the conductor coil 20 by the coil driving device 30 provided with the annular conductor 50 substantially parallel to the annular belt-like magnetic plate 10 at the interval dz. The cancel is generated by applying the cancel current I2 to the annular conductor 50 by the conductor driving device 60 while magnetically shaking the ring-shaped magnetic plate 10 by the magnetic field of Since cancel the leakage magnetic field of the conductor coil 20 outside the magnetic field, it exhibits the following advantageous effects.
（イ）環帯状磁性板１０（磁性体回路）の各段に軸方向に沿って導線コイル２０を巻き付け，環帯状磁性板１０の軸方向の周りに同じ大きさでほぼ逆向きのシェイキング電流を点対称で流すことにより，環帯状磁性板１０の内側に軸方向に沿った均等なシェイキング磁場を発生させ，磁性体内部の磁束を均等に揺らして磁気特性を効率的に向上させることができる。
（ロ）平面Ｐｚ上の環帯状磁性板１０に巻き付けた導線コイル２０の外側には平面Ｐｚと垂直な成分が支配的な漏洩磁場（シェイキングノイズ）を生じるが，環帯状磁性板１０の間隔ｄｚに設けた実質上同径で平行な環状導体５０にキャンセル電流を流すことにより，漏洩磁場と逆向きで平面Ｐｚと垂直なキャンセル磁場が発生するので，そのキャンセル磁場によりシェイキングノイズを効率的に打ち消すことができる。
（ハ）また，環帯状磁性板１０と実質上同径で平行な環状導体５０の発生するキャンセル磁場は，環帯状磁性板１０の軸方向の成分を含まないので，導線コイル２０の発生する軸方向のシェイキング磁場に対する影響を避けながら，導線コイル２０の漏洩磁場を低減することができる。
(A) A conducting coil 20 is wound around each stage of the ring-shaped magnetic plate 10 (magnetic circuit) along the axial direction, and a shaking current having the same size and a substantially opposite direction is applied around the axial direction of the ring-shaped magnetic plate 10. By flowing point-symmetrically, a uniform shaking magnetic field along the axial direction can be generated inside the ring-shaped magnetic plate 10, and the magnetic flux inside the magnetic body can be evenly shaken to improve the magnetic characteristics efficiently.
(B) A leakage magnetic field (shaking noise) in which a component perpendicular to the plane Pz is dominant is generated outside the conducting coil 20 wound around the ring-shaped magnetic plate 10 on the plane Pz. Since a canceling magnetic field is generated in a direction opposite to the leakage magnetic field and perpendicular to the plane Pz by flowing a canceling current through the annular conductor 50 having substantially the same diameter and parallel provided in FIG. 1, the shaking magnetic field effectively cancels the shaking noise. be able to.
(C) Since the canceling magnetic field generated by the annular conductor 50 having substantially the same diameter and parallel to the ring-shaped magnetic plate 10 does not include the axial component of the ring-shaped magnetic plate 10, the axis generated by the conducting coil 20 The leakage magnetic field of the conducting wire coil 20 can be reduced while avoiding the influence of the direction on the shaking magnetic field.
（ニ）複数段の環状導体５０に印加するキャンセル電流は同じ電流値とする必要はなく，導線コイル２０外側の漏洩磁場（シェイキングノイズ）を最も効率的に打ち消すことができるように各環状導体５０のキャンセル電流の電流値を段毎に独立に設定することにより，所要のシェイキング磁場を発生させつつシェイキングノイズの漏洩を最小化することができる。
（ホ）導線コイル２０の巻き付けピッチＴを短くすることでシェイキング磁場を小さな電流量で発生させることが可能となり，所要のシェイキング磁場を発生させる最小の電流量を設定することで，導線コイル２０の外側の漏洩磁場（シェイキングノイズ）を更に低減することができる。
（ヘ）環帯状磁性板１０の内部の磁束を均等に揺らして磁気特性を効率的に向上させると共に，磁気シールド空間へ漏洩する磁場（シェイキングノイズ）を小さく抑えることにより，開放型磁気シールド構造の遮蔽性能を確実且つ大幅に向上させることができる。
(D) The cancel currents applied to the plurality of stages of the annular conductors 50 do not have to have the same current value, and each annular conductor 50 can be canceled most efficiently so as to cancel the leakage magnetic field (shaking noise) outside the conductor coil 20. By setting the current value of the cancellation current independently for each stage, leakage of shaking noise can be minimized while generating a required shaking magnetic field.
(E) It is possible to generate a shaking magnetic field with a small amount of current by shortening the winding pitch T of the conductive coil 20, and by setting a minimum amount of current that generates a required shaking magnetic field, The outside leakage magnetic field (shaking noise) can be further reduced.
(F) The magnetic properties inside the ring-shaped magnetic plate 10 are evenly swayed to improve the magnetic characteristics efficiently, and the magnetic field leaking to the magnetic shield space (shaking noise) is suppressed to a small size. The shielding performance can be improved reliably and significantly.
以下，添付図面を参照して本発明を実施するための形態及び実施例を説明する。
図１は，磁気シールド対象空間１（例えば磁気シールドルーム）の周囲に配置する本発明のシェイキング式の開放型磁気シールド構造の実施例を示す。図１（Ａ）の開放型磁気シールド構造５ｚは，対象空間１の中心点Ｏを貫く第１方向軸Ａｚと所定間隔ｄｚで交差する複数の平行な平面Ｐｚ１，Ｐｚ２，……上にそれぞれ所定帯幅Ｗで空間を囲む環帯状磁性板１０を配置し，図１４（Ｂ）と同様に複数の環帯状磁性板１０によって磁気シールド対象空間１を囲んだものである。図示例は，各環帯状磁性板１０の中心軸である第１方向軸Ａｚを鉛直方向軸（Ｚ軸）としているが，方向軸Ａｚは外来磁場の到来方向に応じて適宜選択可能であり，図１１（Ｂ）及び（Ｃ）に示すように，対象空間１を貫く水平なＸ軸又はＹ軸とすることができる。また，図示例では環帯状磁性板１０を設ける各平面Ｐｚを第１方向軸Ａｚと直交させているが，交差角度を直交以外とすることも可能である。 FIG. 1 shows an embodiment of a shaking type open magnetic shield structure of the present invention disposed around a magnetic shield target space 1 (for example, a magnetic shield room). The open type magnetic shield structure 5z shown in FIG. 1A is predetermined on a plurality of parallel planes Pz1, Pz2,... Intersecting the first direction axis Az penetrating the center point O of the target space 1 at a predetermined interval dz. An annular belt-like magnetic plate 10 surrounding the space with a belt width W is disposed, and the magnetic shield target space 1 is enclosed by a plurality of annular belt-like magnetic plates 10 as in FIG. 14B. In the illustrated example, the first direction axis Az that is the central axis of each ring-shaped magnetic plate 10 is the vertical direction axis (Z axis), but the direction axis Az can be appropriately selected according to the arrival direction of the external magnetic field, As shown in FIGS. 11B and 11C, the horizontal X axis or Y axis that penetrates the target space 1 can be used. In the illustrated example, each plane Pz on which the ring-shaped magnetic plate 10 is provided is orthogonal to the first direction axis Az, but the crossing angle may be other than orthogonal.
環帯状磁性板１０は，例えば図１４（Ａ）に示すように，第１方向軸Ａｚと交差する平面Ｐｚと対象空間の内面との交差線に沿って，帯幅Ｗで適当な長さの複数の帯状導体板２を端縁の重ね合わせによって平らな多角形状（例えば井桁状）に接合することにより作成する。環帯状磁性板１０は，磁気シェイキングにより磁気特性の向上が期待できる磁性体を用いて作成することができ，例えばコバルト系及び鉄系アモルファス，パーマロイ，電磁鋼板等とするが，とくに微弱磁場領域での透磁率が他と比べて格段に高いコバルト系アモルファスとすることが望ましい。一般にコバルト系アモルファスは，最大５０ｍｍ程度の幅の薄帯状磁性板として提供され，それ以上の広幅材料は提供されていないので，密閉型磁気シールド構造では図１５のように複数のアモルファス薄帯を平行に配列して磁気シールド面を形成する手間がかかるが，開放型磁気シールド構造では薄帯状磁性板をそのまま用いて環帯状磁性板１０を形成できるので，開放型磁気シールド構造に適した磁性体ということができる。 For example, as shown in FIG. 14A, the ring-shaped magnetic plate 10 has a band width W and an appropriate length along the intersection line between the plane Pz intersecting the first direction axis Az and the inner surface of the target space. The plurality of strip-shaped conductor plates 2 are formed by joining the edges in a flat polygonal shape (for example, a cross-girder shape). The ring-shaped magnetic plate 10 can be made using a magnetic material that can be expected to improve magnetic properties by magnetic shaking, for example, cobalt-based and iron-based amorphous, permalloy, electromagnetic steel plate, etc., especially in the weak magnetic field region. It is desirable to use a cobalt-based amorphous material whose magnetic permeability is much higher than others. Generally, cobalt-based amorphous is provided as a ribbon-like magnetic plate with a maximum width of about 50 mm, and no wider material is provided. Therefore, in a sealed magnetic shield structure, a plurality of amorphous ribbons are paralleled as shown in FIG. However, in the open type magnetic shield structure, the annular belt-like magnetic plate 10 can be formed using the thin belt-like magnetic plate as it is, so that the magnetic material suitable for the open type magnetic shield structure is used. be able to.
図示例の磁気シールド構造は，開放型磁気シールド構造５ｚの各段の環帯状磁性板１０にそれぞれ環状軸に沿って巻き付けた導線コイル２０（図３（Ｂ）に示す環帯状磁性板１０の平面図を参照）と，その導線コイル２０に所定周波数のシェイキング電流を印加するコイル駆動装置３０とを有する。各段の環帯状磁性板１０（磁性体回路）に巻き付けた導線コイル２０は，環帯状磁性板１０の環状軸と交差する断面（磁性体回路の断面）重心に対して点対称の位置にシェイキング電流を流すので，導線コイル２０の内側に環帯状磁性板１０の軸方向に沿った均等なシェイキング磁場を発生させ，環帯状磁性板１０の内部の磁束を均等に揺らして磁気シェイキング効果を効率的に発揮させることができる。このように磁性体内部の磁束を均等に揺らすことが比較的容易であることから，開放型磁気シールド構造は密閉型磁気シールド構造に比して磁気シェイキングによる遮蔽性能の大幅な向上が期待できる。 The magnetic shield structure in the illustrated example has a conductor coil 20 wound around each ring-shaped magnetic plate 10 of each stage of the open-type magnetic shield structure 5z along the annular axis (a plane of the ring-shaped magnetic plate 10 shown in FIG. 3B). And a coil driving device 30 for applying a shaking current having a predetermined frequency to the conducting wire coil 20. The conducting coil 20 wound around the ring-shaped magnetic plate 10 (magnetic circuit) of each stage is shaken at a point-symmetrical position with respect to the center of gravity of the cross-section (cross-section of the magnetic circuit) intersecting the annular axis of the ring-shaped magnetic plate 10. Since an electric current flows, a uniform shaking magnetic field along the axial direction of the ring-shaped magnetic plate 10 is generated inside the conductor coil 20, and the magnetic flux inside the ring-shaped magnetic plate 10 is evenly shaken to efficiently produce the magnetic shaking effect. Can be demonstrated. As described above, since the magnetic flux inside the magnetic body can be relatively easily shaken, the open type magnetic shield structure can be expected to greatly improve the shielding performance by magnetic shaking as compared with the closed type magnetic shield structure.
また，図示例の磁気シールド構造は，各段の開放型磁気シールド構造５ｚの間隔ｄｚにそれぞれ環帯状磁性板１０と実質上同径で平行に設けた環状導体５０と，その環状導体５０にキャンセル電流を印加する導体駆動装置６０とを有する。後述するように（実験例２参照），環帯状磁性板１０に巻き付けた導線コイル２０は，その環帯状磁性板１０の平面Ｐｚと垂直な方向が支配的な漏洩磁場（シェイキングノイズ）を生じるが，環帯状磁性板１０と実質上同径で平行な環状導体５０にキャンセル電流を流すことにより，漏洩磁場と逆向きで平面Ｐｚと垂直なキャンセル磁場が発生するので，そのキャンセル磁場によりシェイキングノイズを効率的に打ち消すことができる。また，環帯状磁性板１０と実質上同径で平行な環状導体５０の発生するキャンセル磁場は，環帯状磁性板１０の軸方向の成分を含まないので，導線コイル２０の発生する軸方向のシェイキング磁場に対する影響を避けながらシェイキングノイズを低減することができる。 Further, the magnetic shield structure of the illustrated example has an annular conductor 50 provided substantially in parallel with the ring-shaped magnetic plate 10 at the interval dz between the open magnetic shield structures 5z of each stage, and the annular conductor 50 cancels the annular conductor 50. And a conductor driving device 60 for applying a current. As will be described later (see Experimental Example 2), the conductor coil 20 wound around the ring-shaped magnetic plate 10 generates a leakage magnetic field (shaking noise) whose direction perpendicular to the plane Pz of the ring-shaped magnetic plate 10 is dominant. Since a canceling magnetic field is generated in a direction opposite to the leakage magnetic field and perpendicular to the plane Pz by flowing a canceling current through the annular conductor 50 having substantially the same diameter and parallel to the ring-shaped magnetic plate 10, a shaking magnetic field is generated by the canceling magnetic field. It can be canceled out efficiently. Further, since the canceling magnetic field generated by the annular conductor 50 having substantially the same diameter and parallel to the ring-shaped magnetic plate 10 does not include the axial component of the ring-shaped magnetic plate 10, the axial shaking generated by the conducting coil 20 is performed. Shaking noise can be reduced while avoiding the influence on the magnetic field.
［実験例１］
先ず，開放型磁気シールド構造５ｚの各段の環帯状磁性板１０にそれぞれ導線コイル２０を巻き付けた場合の漏洩磁場（シェイキングノイズ）を確認するため，図２に示すようなモデル実験を行った。本実験では，図２（Ａ）に示すように幅５０ｍｍ，長さ１０００ｍｍ，厚さ５ｍｍの帯状磁性板４枚を井桁状に接合して外形９５０ｍｍの環帯状磁性板１０（磁性体回路）を構成し，その環帯状磁性板１０を所定間隔ｄｚ＝２００ｍｍで５段配置して開放型磁気シールド構造５ｚを形成し，各段の環帯状磁性板１０にそれぞれ環状軸と直角方向に導線コイル２０を所定ピッチＴで巻き付けてシェイキング電流（周波数２００Ｈｚ）を印加した。環帯状磁性板１０の外形の大きさは，環状の磁性体回路の中心軸の長さを表している。図２（Ｂ）はこの開放型磁気シールド構造５ｚのＸＹ平面と平行な平面図を示し，図２（Ｃ）はこの開放型磁気シールド構造５ｚのＹＺ平面と平行な断面図を示し，図２（Ｄ）は図２（Ｂ）の楕円Ｄ部分を拡大したコイル電流の模式的平面図を示し，図２（Ｅ）は環帯状磁性板１０の環状軸方向から見たコイル電流の模式的側面図を示す。この場合の導線コイル２０は，図２（Ｂ）及び（Ｄ）に示すように相互に連続しておらず，所定ピッチＴ間隔の巻き付け位置毎に相互に独立した閉回路を想定した。図２（Ｃ）及び（Ｅ）に示す各コイル（以下，１段コイルということがある）２０は，発生する磁場の相殺効果を考慮して，磁性体回路の断面の重心に対して点対称の位置に配置されており，断面の大きさは５０ｍｍ×５ｍｍである。
[Experimental Example 1]
First, in order to confirm the leakage magnetic field (shaking noise) when the conducting coil 20 is wound around the ring-shaped magnetic plate 10 of each stage of the open type magnetic shield structure 5z, a model experiment as shown in FIG. 2 was performed. In this experiment, as shown in FIG. 2 (A), four belt-like magnetic plates having a width of 50 mm, a length of 1000 mm, and a thickness of 5 mm were joined in a cross-beam shape to form an annular belt-like magnetic plate 10 (magnetic circuit) having an outer shape of 950 mm. The ring-shaped magnetic plate 10 is arranged in five stages at a predetermined interval dz = 200 mm to form an open-type magnetic shield structure 5z, and each of the ring-shaped magnetic plates 10 at each stage has a conductor coil 20 perpendicular to the annular axis. Was wound at a predetermined pitch T, and a shaking current (frequency: 200 Hz) was applied. The size of the outer shape of the ring-shaped magnetic plate 10 represents the length of the central axis of the annular magnetic circuit. 2B shows a plan view parallel to the XY plane of the open type magnetic shield structure 5z, and FIG. 2C shows a cross-sectional view parallel to the YZ plane of the open type magnetic shield structure 5z. 2D is a schematic plan view of the coil current obtained by enlarging the ellipse D portion of FIG. 2B, and FIG. 2E is a schematic side view of the coil current viewed from the annular axis direction of the ring-shaped magnetic plate 10. The figure is shown. As shown in FIGS. 2B and 2D, the conducting coil 20 in this case is not continuous with each other, and a closed circuit independent of each other at each winding position with a predetermined pitch T interval is assumed. Each coil 20 (hereinafter also referred to as a single-stage coil) 20 shown in FIGS. 2C and 2E is point-symmetric with respect to the center of gravity of the cross section of the magnetic circuit circuit in consideration of the canceling effect of the generated magnetic field. The cross-sectional size is 50 mm × 5 mm.
また，比較のため，図６に示すように開放型磁気シールド構造５ｚの５段の環帯状磁性板１０（磁性体回路）にまとめて導線コイル２０を所定ピッチＴで巻き付けてシェイキング電流（周波数２００Ｈｚ）を印加する実験を行った。図６に示す各コイル（以下，５段コイルということがある）２０も相互に連続しておらず，所定ピッチＴ間隔の巻き付け位置毎に相互に独立した閉回路を想定し，断面の大きさは５０ｍｍ×８０５ｍｍである。図２の１段コイルと図６の５段コイルとにそれぞれシェイキング電流を印加し，コイル内側の発生磁場とコイル外側の漏洩磁場とをそれぞれ数値シミュレーション（三次元非線形磁場解析）により求めた。 For comparison, as shown in FIG. 6, a conducting coil 20 is wound around a five-step annular magnetic plate 10 (magnetic circuit) of an open magnetic shield structure 5z and wound at a predetermined pitch T to obtain a shaking current (frequency 200 Hz). ) Was applied. Each coil (hereinafter also referred to as a five-stage coil) 20 shown in FIG. 6 is not continuous with each other, and assumes a closed circuit independent at each winding position with a predetermined pitch T interval. Is 50 mm × 805 mm. Shaking currents were applied to the 1-stage coil of FIG. 2 and the 5-stage coil of FIG. 6, respectively, and the generated magnetic field inside the coil and the leakage magnetic field outside the coil were obtained by numerical simulation (three-dimensional nonlinear magnetic field analysis).
なお本実験では，図２の１段コイルと図６の５段コイルとで磁性体回路のシェイキング強度を揃えるため，環帯状磁性板１０の内部に誘起される磁束密度が一致するように１段コイル及び５段コイルのシェイキング電流を設定した。すなわち，図２の１段コイルに１Ａのシェイキング電流を印加したときの各段の磁性体回路の辺中央の磁束密度は１９．６ｍＴであるのに対し，図６の５段コイルに１Ａのシェイキング電流を印加したときの各段の磁性体回路の辺中央の磁束密度は，１段目及び５段目では３８.７ｍＴ，２段目〜４段目では５７．８ｍＴとなり，何れも１段コイルより大きくなった。これは５段コイルが各段の磁性体回路の間に跨っており，電流路が長いことに起因する。そのため，２段目〜４段目の磁束密度が１段コイルの１９．６ｍＴと一致するように，５段コイルに印加するシェイキング電流の電流値を０．３３９Ａと設定した。 In this experiment, in order to make the shaking strength of the magnetic circuit uniform between the one-stage coil shown in FIG. 2 and the five-stage coil shown in FIG. 6, the one-stage coil so that the magnetic flux densities induced inside the annular magnetic plate 10 match. The shaking current of the coil and the 5-stage coil was set. That is, when a 1 A shaking current is applied to the 1-stage coil of FIG. 2, the magnetic flux density at the center of each side of the magnetic circuit of each stage is 19.6 mT, whereas the 1-A shaking is applied to the 5-stage coil of FIG. The magnetic flux density at the center of each stage of the magnetic circuit at each stage when current is applied is 38.7 mT in the first and fifth stages, and 57.8 mT in the second to fourth stages. It became bigger. This is due to the fact that the 5-stage coil straddles between the magnetic circuit of each stage and the current path is long. For this reason, the current value of the shaking current applied to the 5-stage coil was set to 0.339 A so that the magnetic flux density of the second to fourth stages coincided with 19.6 mT of the first-stage coil.
図４（Ａ）及び（Ｂ）は，図２の１段コイル外側の漏洩磁場を，図２（Ｂ）及び（Ｃ）に示す開放型磁気シールド構造内側の評価対象域Ｒの磁場分布のコンター図・ベクトル図として表したものである。また図７（Ａ）及び（Ｂ）は，図６の５段コイル外側の漏洩磁場を評価対象域Ｒの磁場分布のコンター図・ベクトル図として表したものである。なお，図４及び図７はそれぞれ磁性体回路が存在しないコイルのみを配置した場合の漏洩磁場を示しており，磁性体回路が存在する場合は，シェイキング電流により磁化された磁性体から発生する磁場が重畳されるため評価対象域Ｒの磁場分布は大きくなる。ただし，磁性体の種類，厚さ（積層枚数），大きさなどにより重畳される値は様々に変わるため，シェイキングコイルから発生する磁場のみを評価するためには，磁性体回路のないコイルのみの漏洩磁場を考慮することが有効である。 4 (A) and 4 (B) show the magnetic field distribution of the magnetic field distribution in the evaluation target region R inside the open type magnetic shield structure shown in FIGS. 2 (B) and 2 (C). It is represented as a figure / vector diagram. FIGS. 7A and 7B show the leakage magnetic field outside the five-stage coil in FIG. 6 as a contour diagram / vector diagram of the magnetic field distribution in the evaluation target region R. FIG. 4 and 7 each show a leakage magnetic field when only a coil having no magnetic circuit is arranged. When a magnetic circuit is present, the magnetic field generated from the magnetic material magnetized by the shaking current is shown. Is superimposed, the magnetic field distribution in the evaluation target region R becomes large. However, the superimposed value varies depending on the type, thickness (number of stacked layers), size, etc. of the magnetic material. Therefore, in order to evaluate only the magnetic field generated from the shaking coil, It is effective to consider the leakage magnetic field.
１段コイルの作る図４の磁場分布と，５段コイルの作る図７の磁場分布とを比較すると，１段コイルのほうが１／１３程度小さくなっていることが分かる。また，いずれの場合も，漏洩磁場は水平成分のみであり，垂直方向の磁場は殆ど漏洩していないことが分かる。この理由は，図２（Ｄ）及び（Ｅ）に示すコイル電流の模式図から分かるように，コイルに流れる電流Ｉａ，Ｉｂ，Ｉｃ，Ｉｄは磁性体回路の断面の重心に対して点対称の位置（環状軸方向から見て点対称の位置）にあり，同じ大きさで方向が異なるため，電流Ｉａ及びＩｃから発生する磁場（垂直成分）は打ち消し合ってゼロとなり，電流Ｉｂ及びＩｄから発生する磁場（水平成分）のみが評価対象域Ｒに漏洩するからである。５段コイルは，電流値は小さいにも拘わらず，磁場の水平成分を誘起する垂直電流路が長いため，漏洩磁場が大きくなっている。もっとも垂直方向の漏洩磁場についても，コイル近傍（評価対象域Ｒの周縁）では比較的大きいが，コイルから離れるに従って打ち消し合う効果が高まり，評価対象域Ｒの中心部（磁気シールド対象空間の中心部）では一気に小さくなっている。 Comparing the magnetic field distribution of FIG. 4 produced by the single-stage coil with the magnetic field distribution of FIG. 7 produced by the five-stage coil, it can be seen that the single-stage coil is about 1/13 smaller. In either case, the leakage magnetic field is only the horizontal component, and it can be seen that the magnetic field in the vertical direction hardly leaks. The reason for this is that the currents Ia, Ib, Ic, Id flowing through the coil are point-symmetric with respect to the center of gravity of the cross section of the magnetic circuit, as can be seen from the schematic diagrams of the coil currents shown in FIGS. Because it is in a position (a point-symmetrical position when viewed from the annular axis direction), the direction is the same and the directions are different. This is because only the magnetic field (horizontal component) to be leaked to the evaluation target region R. Although the 5-stage coil has a small current value, the leakage magnetic field is large because the vertical current path for inducing the horizontal component of the magnetic field is long. Of course, the leakage magnetic field in the vertical direction is relatively large in the vicinity of the coil (periphery of the evaluation target area R), but the effect of canceling out increases as the distance from the coil increases. ) Is getting smaller at once.
図４及び図７の磁場分布の比較から，図２のように開放型磁気シールド構造５ｚの各段の環帯状磁性板１０にそれぞれ環状軸に沿って導線コイル２０を巻き付けてシェイキング電流を印加することにより，導線コイル２０の外側に漏洩する磁場（シェイキングノイズ）を十分に低減できることが分かる。密閉型磁気シールド構造をシェイキングする場合は図６と同様の５段コイルが必要であることから，開放型磁気シールド構造は密閉型磁気シールド構造に比して磁気シェイキングの漏洩磁場を小さくできる利点があるといえる。また，図２（Ｅ）に示すように，磁性体回路の軸方向から見て点対称の位置に巻き付けた１段コイルは，磁性体回路の内部に軸方向に沿ったシェイキング磁場のみを発生させるので，環帯状磁性板内部の磁束を均等に揺らせることが分かる。 From comparison of the magnetic field distributions in FIGS. 4 and 7, as shown in FIG. 2, a conducting coil 20 is wound around each ring-shaped magnetic plate 10 of each stage of the open magnetic shield structure 5 z along the annular axis to apply a shaking current. This shows that the magnetic field (shaking noise) leaking to the outside of the conducting wire coil 20 can be sufficiently reduced. When a sealed magnetic shield structure is shaken, the same five-stage coil as in FIG. 6 is required. Therefore, the open type magnetic shield structure has the advantage that the magnetic field of the magnetic shaking can be reduced compared to the sealed magnetic shield structure. It can be said that there is. In addition, as shown in FIG. 2E, a single-stage coil wound around a point-symmetrical position when viewed from the axial direction of the magnetic circuit generates only a shaking magnetic field along the axial direction inside the magnetic circuit. Therefore, it can be seen that the magnetic flux inside the ring-shaped magnetic plate is evenly swayed.
［実験例２］
図２のモデル実験では，環帯状磁性板１０の所定ピッチＴの巻き付け位置毎に独立した閉回路コイルを巻き付けているが，実際の開放型磁気シールド構造５ｚの環帯状磁性板１０をシェイキングする場合は閉回路コイルとすることは難しい。そこで次に，図３のように各段の環帯状磁性板１０の環状軸に沿って所定ピッチＴで連続的に導線コイル２０に巻き付けた場合の漏洩磁場（シェイキングノイズ）を確認するため，上述した実験例１と同様に外形（環状の磁性体回路の中心軸の長さ）９５０ｍｍの環帯状磁性板１０（磁性体回路）を所定間隔ｄｚ＝２００ｍｍで５段配置して開放型磁気シールド構造５ｚを形成し，図３（Ｂ）及び（Ｃ）に示すように５段の環帯状磁性板１０の環状軸方向にそれぞれ所定ピッチＴ（１００ｍｍ幅で１ターン，環帯状磁性板の各辺（９００ｍｍ）で９ターン）で連続的に導線コイル２０を巻き付けてシェイキング電流（周波数２００Ｈｚ）を印加し，コイル内側の発生磁場とコイル外側の漏洩磁場とをそれぞれ数値シミュレーションにより求める実験を行った。図３（Ｂ）はこの開放型磁気シールド構造５ｚのＸＹ平面と平行な平面図を示し，図３（Ｃ）はこの開放型磁気シールド構造５ｚのＹＺ平面と平行な断面図を示し，図３（Ｄ）は図３（Ｂ）の楕円Ｄ部分を拡大したコイル電流の模式的平面図を示し，図３（Ｅ）は環帯状磁性板１０の環状軸方向から見たコイル電流の模式的側面図を示す。
[Experiment 2]
In the model experiment of FIG. 2, an independent closed circuit coil is wound at each winding position of the ring-shaped magnetic plate 10 at a predetermined pitch T. When the ring-shaped magnetic plate 10 of the actual open-type magnetic shield structure 5z is shaken. Is difficult to make a closed circuit coil. Therefore, in order to confirm the leakage magnetic field (shaking noise) when continuously wound around the conducting coil 20 at a predetermined pitch T along the annular axis of the annular magnetic plate 10 at each stage as shown in FIG. In the same manner as in Experimental Example 1, an annular magnetic plate 10 (magnetic circuit) having an outer shape (the length of the central axis of the annular magnetic circuit) of 950 mm is arranged in five stages at a predetermined interval dz = 200 mm, and an open type magnetic shield structure 5z, and as shown in FIGS. 3B and 3C, each turn (100 mm width for one turn, each side of the ring-shaped magnetic plate (100 mm width) in the direction of the annular axis of the five-step ring-shaped magnetic plate 10 900 mm) and 9 turns), the coil 20 is continuously wound and a shaking current (frequency 200 Hz) is applied, and the generated magnetic field inside the coil and the leakage magnetic field outside the coil are obtained by numerical simulation. Experiments were carried out. 3B shows a plan view parallel to the XY plane of this open type magnetic shield structure 5z, and FIG. 3C shows a cross-sectional view parallel to the YZ plane of this open type magnetic shield structure 5z. 3D is a schematic plan view of the coil current obtained by enlarging the ellipse D portion of FIG. 3B, and FIG. 3E is a schematic side view of the coil current viewed from the annular axis direction of the ring-shaped magnetic plate 10. The figure is shown.
また，比較のため，図８に示すように開放型磁気シールド構造５ｚの５段の環帯状磁性板１０（磁性体回路）にまとめて導線コイル２０を所定ピッチＴ（１００ｍｍ幅で１ターン，環帯状磁性板の各辺（９００ｍｍ）で９ターン）で連続的に巻き付けてシェイキング電流を印加し，コイル内側の発生磁場とコイル外側の漏洩磁場とをそれぞれ数値シミュレーションにより求める実験を行った。環帯状磁性板１０の内部に誘起される磁束密度を実験例１（図２の１段コイルの場合）と揃えるため，図３の１段コイルに印加するシェイキング電流の電流値を１．４１４Ａと設定し，図８の５段コイルに印加するシェイキング電流の電流値は０．３３９Ａと設定した。 For comparison, as shown in FIG. 8, the conductor coil 20 is put together on a five-stage annular belt-like magnetic plate 10 (magnetic circuit) of the open type magnetic shield structure 5z so that the conductor coil 20 is turned at a predetermined pitch T (100 mm width, one turn). An experiment was performed in which a magnetic field generated inside the coil and a leakage magnetic field outside the coil were respectively obtained by numerical simulation by applying a shaking current by continuously winding the belt-shaped magnetic plate on each side (900 mm, 9 turns). In order to align the magnetic flux density induced inside the ring-shaped magnetic plate 10 with that of Experimental Example 1 (in the case of the single-stage coil in FIG. 2), the current value of the shaking current applied to the single-stage coil in FIG. The current value of the shaking current applied to the 5-stage coil of FIG. 8 was set to 0.339A.
図５（Ａ）及び（Ｂ）は，図３の１段コイル外側の漏洩磁場を，開放型磁気シールド構造内側の評価対象域Ｒの磁場分布のコンター図・ベクトル図として表したものである。また図９（Ａ）及び（Ｂ）は，図８の５段コイル外側の漏洩磁場を評価対象域Ｒの磁場分布のコンター図・ベクトル図として表したものである。図５及び図９も，実験例１の図４及び図７の場合と同様に，磁性体から発生する磁場の重畳を避けるため，磁性体回路が存在しないコイルのみを配置した場合の漏洩磁場を示している。 5A and 5B show the leakage magnetic field outside the first stage coil of FIG. 3 as a contour diagram / vector diagram of the magnetic field distribution in the evaluation target region R inside the open type magnetic shield structure. FIGS. 9A and 9B show the leakage magnetic field outside the five-stage coil of FIG. 8 as a contour diagram and vector diagram of the magnetic field distribution in the evaluation target region R. FIG. 5 and 9 also show the leakage magnetic field when only the coil having no magnetic material circuit is arranged in order to avoid the superposition of the magnetic field generated from the magnetic material, as in the case of FIGS. Show.
１段コイルの作る図５の磁場分布と，５段コイルの作る図９の磁場分布とを比較すると，何れも漏洩磁場は垂直成分が支配的であり，１段コイルのほうが３０倍程度大きくなっていることが分かる。この理由は，図３（Ｄ）及び（Ｅ）に示すコイル電流の模式図から分かるように，コイルに流れる電流Ｉａ，Ｉｃは同じ大きさであるがＸＹ平面上で方向が異なっているため，発生する磁場の垂直成分を打ち消し合う効果が不十分となるからである。図９の５段コイルでは，電流Ｉａ，Ｉｃが離れているのである程度の打ち消し効果が見られるが，図５の１段コイルでは漏洩磁場の垂直成分が大きくなっている。なお，コイルに流れる電流Ｉｂ，ＩｄもＹ軸方向で位置がずれているが，漏洩磁場（水平成分）への影響は比較的小さい。 Comparing the magnetic field distribution of FIG. 5 made by the single-stage coil with the magnetic field distribution of FIG. 9 made by the five-stage coil, the leakage magnetic field has a dominant vertical component, and the single-stage coil is about 30 times larger. I understand that The reason for this is that, as can be seen from the schematic diagrams of the coil currents shown in FIGS. 3D and 3E, the currents Ia and Ic flowing through the coils have the same magnitude but different directions on the XY plane. This is because the effect of canceling out the vertical component of the generated magnetic field is insufficient. In the five-stage coil of FIG. 9, the currents Ia and Ic are separated, so that a certain amount of cancellation effect is seen. However, in the single-stage coil of FIG. 5, the vertical component of the leakage magnetic field is large. The positions of the currents Ib and Id flowing through the coils are also shifted in the Y-axis direction, but the influence on the leakage magnetic field (horizontal component) is relatively small.
図５及び図９の磁場分布の比較から，開放型磁気シールド構造の磁性体回路に所定ピッチＴ（１００ｍｍ幅で１ターン）で連続的に導線コイル２０を巻き付けてシェイキング電流を印加した場合は，図８の５段コイルの漏洩磁場よりも図３の１段コイルの漏洩磁場が大きいことが分かる。すなわち，図３のように環帯状磁性板１０の環状軸方向から見て点対称の位置にシェイキング電流を流す１段コイルは，環帯状磁性板１０の内部の磁束を均等に揺らして磁気シェイキング効果を効率的に発揮させるために有効であるが，シェイキング電流に伴う漏洩磁場（シェイキングノイズ）によって磁気環境が劣化することが懸念される。 From the comparison of the magnetic field distributions in FIGS. 5 and 9, it is found that when the conducting coil 20 is continuously wound around the magnetic circuit of the open magnetic shield structure at a predetermined pitch T (one turn with a width of 100 mm) and a shaking current is applied, It can be seen that the leakage magnetic field of the first stage coil of FIG. 3 is larger than the leakage magnetic field of the five stage coil of FIG. That is, as shown in FIG. 3, the one-stage coil for passing a shaking current at a point-symmetrical position when viewed from the annular axis direction of the ring-shaped magnetic plate 10 uniformly shakes the magnetic flux inside the ring-shaped magnetic plate 10 to achieve the magnetic shaking effect. However, there is a concern that the magnetic environment may deteriorate due to the leakage magnetic field (shaking noise) accompanying the shaking current.
なお，図３の開放型磁気シールド構造５ｚでは，５段配置の環帯状磁性板１０にそれぞれ導線コイル２０を連続的に巻き付け，そのコイル２０の一端及び他端を入出力ライン２０ａ，２０ｂに接続し，交流電源であるコイル駆動装置３０から入出力ライン２０ａ，２０ｂにシェイキング電流を印加している。この場合に，各段の磁性体回路に巻き付けたコイル２０と共に入出力ライン２０ａ，２０ｂからの磁場の漏洩も問題となりうるが，図示例のように入出力ライン２０ａ，２０ｂを隣接させて平行に配置することにより，入出力ライン２０ａ，２０ｂの発生磁場を逆向きの入出力電流によって打ち消して漏洩磁場を小さく抑えることができる。必要に応じて出力ライン２０ａ，２０ｂを撚ることにより打ち消し効果を高めることも有効である。ただし，導線コイル２０は，図示例のように複数段の環帯状磁性板１０に連続的に巻き付ける必要はなく，少なくとも１つの段において連続していれば足りる。その場合は，段毎にコイル駆動装置３０を設けて段毎の導線コイル２０にシェイキング電流を個別に印加する。 In the open type magnetic shield structure 5z shown in FIG. 3, the conductive coil 20 is continuously wound around the annular belt-like magnetic plate 10 arranged in five stages, and one end and the other end of the coil 20 are connected to the input / output lines 20a and 20b. In addition, a shaking current is applied to the input / output lines 20a and 20b from the coil driving device 30 which is an AC power supply. In this case, leakage of the magnetic field from the input / output lines 20a and 20b together with the coil 20 wound around the magnetic circuit at each stage may be a problem, but the input / output lines 20a and 20b are adjacent to each other in parallel as in the illustrated example. By disposing, the magnetic field generated in the input / output lines 20a and 20b can be canceled by the input / output current in the reverse direction, and the leakage magnetic field can be kept small. It is also effective to enhance the cancellation effect by twisting the output lines 20a and 20b as necessary. However, the conductor coil 20 does not need to be continuously wound around a plurality of stages of the annular belt-like magnetic plate 10 as in the illustrated example, and it is sufficient if it is continuous in at least one stage. In that case, a coil driving device 30 is provided for each stage, and a shaking current is individually applied to the conductive wire coil 20 for each stage.
［実験例３］
図３のように各段の環帯状磁性板１０の各辺に所定ピッチＴで連続的に導線コイル２０に巻き付けた開放型磁気シールド構造５ｚにおいて，図３（Ｄ）及び（Ｅ）に示す所定ピッチＴの導線コイル２０のコイル電流Ｉａ，Ｉｃを，図２（Ｄ）及び（Ｅ）に示す導線コイル２０のコイル電流Ｉａ，ＩｃのようにＸＹ平面上で近付ければ，図３の１段コイル２０の作る図５の磁場分布を，図２の１段コイル２０の作る図４の磁場分布に近付けて漏洩磁場を低減することが期待できる。そこで，図３の環帯状磁性板１０の各辺（９００ｍｍ）に連続的に巻き付ける導線コイル２０の所定ピッチＴを，（ａ）１００ｍｍ（９００ｍｍ幅で９ターン），（ｂ）５０ｍｍ（９００ｍｍ幅では１８ターン），（ｃ）２０ｍｍ（９００ｍｍ幅では４５ターン），（ｄ）１０ｍｍ（９００ｍｍ幅では９０ターン）と変えながら，評価対象域Ｒの漏洩磁場を数値シミュレーションにより順次求める実験を繰り返した。
[Experiment 3]
As shown in FIG. 3, in the open type magnetic shield structure 5z continuously wound around the conductor coil 20 at a predetermined pitch T around each side of the annular band-shaped magnetic plate 10 in each step, the predetermined shown in FIGS. 3D and 3E. If the coil currents Ia and Ic of the conductor coil 20 having the pitch T are brought close to each other on the XY plane like the coil currents Ia and Ic of the conductor coil 20 shown in FIGS. It can be expected that the magnetic field distribution of FIG. 5 made by the coil 20 is brought close to the magnetic field distribution of FIG. 4 made by the single-stage coil 20 of FIG. 2 to reduce the leakage magnetic field. Therefore, the predetermined pitch T of the conductive coil 20 continuously wound around each side (900 mm) of the ring-shaped magnetic plate 10 of FIG. 3 is (a) 100 mm (900 mm width 9 turns), (b) 50 mm (900 mm width) 18 turns), (c) 20 mm (45 turns for a 900 mm width), and (d) 10 mm (90 turns for a 900 mm width), and the experiment for sequentially obtaining the leakage magnetic field in the evaluation target region R by numerical simulation was repeated.
導線コイル２０の所定ピッチＴに拘わらず，環帯状磁性板１０の内部に誘起される磁束密度を実験例１（図２の１段コイルの場合）と揃えると，（ａ）所定ピッチＴ＝１００ｍｍのときはシェイキング電流の電流値を１．４１４Ａ，（ｂ）５０ｍｍのときは１．１１８Ａ，（ｃ）２０ｍｍのときは１．０２０Ａ，（ｄ）１０ｍｍのときは１．００５Ａとなる。また，所定ピッチＴを小さくするとターン数（巻き数）が多くなるので，ターン数の増加に応じてシェイキング電流の電流値を小さくすることにより，シェイキングノイズの漏洩を更に低減することが期待できる。 Regardless of the predetermined pitch T of the conductor coil 20, when the magnetic flux density induced in the ring-shaped magnetic plate 10 is aligned with that of Experimental Example 1 (in the case of the single-stage coil in FIG. 2), (a) the predetermined pitch T = 100 mm In this case, the current value of the shaking current is 1.414 A, (b) 50 mm is 1.118 A, (c) 20 mm is 1.020 A, and (d) 10 mm is 1.005 A. Moreover, since the number of turns (the number of turns) increases when the predetermined pitch T is reduced, it is expected that the leakage of the shaking noise can be further reduced by reducing the current value of the shaking current as the number of turns increases.
一般に環帯状磁性板１０の内部をシェイキングするために必要なシェイキング電流（励磁電流）は，巻き付けた導線コイル２０の電流値（Ａ）×ターン数（Ｔ）＝アンペアターン（ＡＴ）で表すことができる。そこで本実験では，導線コイル２０の所定ピッチＴに拘わらず，ターン数を考慮してアンペアターン（ＡＴ）が実験例１（図２の１段コイルの場合）と一致するように，（ａ）所定ピッチＴ＝１００ｍｍのときはシェイキング電流の電流値を１．４１４Ａ，（ｂ）５０ｍｍのときは０．５５９Ａ，（ｃ）２０ｍｍのときは０．２０４Ａ，（ｄ）１０ｍｍのときは０．１００Ａに設定した。本実験の結果を表１，及び図１０のグラフに示す。 In general, the shaking current (excitation current) necessary to shake the inside of the ring-shaped magnetic plate 10 can be expressed by the current value (A) of the wound conductive coil 20 × the number of turns (T) = ampere turns (AT). it can. Therefore, in this experiment, (a) so that the ampere turn (AT) coincides with Experimental Example 1 (in the case of the one-stage coil in FIG. 2) in consideration of the number of turns, regardless of the predetermined pitch T of the conductor coil 20. When the predetermined pitch T = 100 mm, the current value of the shaking current is 1.414 A, (b) 0.559 A when 50 mm, (c) 0.204 A when 20 mm, and (d) 0.100 A when 10 mm. Set to. The results of this experiment are shown in Table 1 and the graph of FIG.
表１の５段コイル（連続）の欄は，図８のように５段の環帯状磁性板１０に所定ピッチ１００ｍｍで連続的に巻き付けた導線コイル２０の評価対象域Ｒにおける漏洩磁場を示す。また表１の１段コイル（連続）の漏洩磁場の平均値欄は，図３の１段導線コイル２０の所定ピッチＴを１００ｍｍ，５０ｍｍ，２０ｍｍ，１０ｍｍと切り替えたときの評価対象域Ｒの漏洩磁場の水平面における平均値，及び垂直面における平均値の変化をそれぞれ示している。図１０は，表１の１段コイル（連続）の水平面における漏洩磁場の水平成分，垂直成分，及び両者を合成した漏洩磁場の平均値の変化をグラフで表している。図１０（Ｂ）及び（Ｃ）のグラフから分かるように，図３の１段コイルのつくる漏洩磁場の垂直成分は，図８の５段コイルのつくる漏洩磁場の垂直成分よりも大きいが，１段コイルの所定ピッチＴを小さく（ターン数を大きく）するとコイル電流Ｉａ，ＩｃがＸＹ平面において接近するので（図３（Ｄ）及び（Ｅ）参照），漏洩磁場の打ち消し率を高めて垂直成分を低減することができる。 The column of 5-stage coil (continuous) in Table 1 shows the leakage magnetic field in the evaluation target region R of the conductive coil 20 continuously wound around the 5-stage annular belt-like magnetic plate 10 at a predetermined pitch of 100 mm as shown in FIG. The average value field of the leakage magnetic field of the first stage coil (continuous) in Table 1 shows the leakage of the evaluation target area R when the predetermined pitch T of the first stage conductive coil 20 in FIG. 3 is switched to 100 mm, 50 mm, 20 mm, and 10 mm. The average value of the magnetic field in the horizontal plane and the change in the average value in the vertical plane are shown. FIG. 10 is a graph showing changes in the horizontal and vertical components of the leakage magnetic field in the horizontal plane of the one-stage coil (continuous) in Table 1 and the average value of the leakage magnetic field obtained by combining both. As can be seen from the graphs of FIGS. 10B and 10C, the vertical component of the leakage magnetic field generated by the one-stage coil of FIG. 3 is larger than the vertical component of the leakage magnetic field generated by the five-stage coil of FIG. When the predetermined pitch T of the step coil is reduced (the number of turns is increased), the coil currents Ia and Ic approach in the XY plane (see FIGS. 3D and 3E), so that the canceling rate of the leakage magnetic field is increased and the vertical component is increased. Can be reduced.
表１及び図１０のグラフから，磁気シールド空間１を囲む環帯状磁性板１０の各段に軸方向に沿って導線コイル（１段コイル）２０を所定ピッチＴで巻き付け，導線コイル２０外側の漏洩磁場が打ち消されるように導線コイル２０の所定巻き付けピッチＴを設定することにより，環帯状磁性板１０の内部の磁束を均等に揺らして磁気特性を効率的に向上させると同時に，磁気シールド空間１への漏洩磁場（シェイキングノイズ）を小さく抑えられることが分かる。ただし，１段コイルの所定ピッチＴを１０ｍｍにまで小さくしても，漏洩磁場は所定ピッチが１００ｍｍの５段コイルよりも小さくならないので，漏洩磁場を更に低減するためにはピッチの設定以外の対策が求められる。 From the graphs of Table 1 and FIG. 10, a conducting coil (one-stage coil) 20 is wound around each stage of the ring-shaped magnetic plate 10 surrounding the magnetic shield space 1 along the axial direction at a predetermined pitch T, and leakage outside the conducting coil 20 is detected. By setting a predetermined winding pitch T of the conductive coil 20 so that the magnetic field is canceled, the magnetic flux inside the ring-shaped magnetic plate 10 is evenly shaken to improve the magnetic characteristics efficiently, and at the same time to the magnetic shield space 1. It can be seen that the leakage magnetic field (shaking noise) can be kept small. However, even if the predetermined pitch T of the first stage coil is reduced to 10 mm, the leakage magnetic field does not become smaller than that of the five-stage coil having a predetermined pitch of 100 mm. Therefore, in order to further reduce the leakage magnetic field, measures other than the pitch setting are required. Is required.
もっとも，表１及び図１０のグラフは図３のモデル実験による漏洩磁場のシミュレーション結果であり，モデルが異なれば漏洩磁場も異なってくる。図３のモデル実験は比較的小型であるため漏洩磁場が大きくなっているが，磁気シールド空間１の大きさが変わると距離減衰効果によって漏洩磁場は低下し，通常の医療施設や研究施設の磁気シールドルームのサイズまで大きくすると漏洩磁場は大幅に低下するものと考えられる。すなわち，設計条件及び要求性能に応じて導線コイル２０の所定ピッチＴを適切に設定すれば，本発明のシェイキング式の開放型磁気シールド構造は十分に実用化可能である。 However, the graphs in Table 1 and FIG. 10 are the simulation results of the leakage magnetic field by the model experiment of FIG. 3, and the leakage magnetic field differs depending on the model. Although the model experiment of FIG. 3 is relatively small, the leakage magnetic field is large. However, when the size of the magnetic shield space 1 is changed, the leakage magnetic field is reduced by the distance attenuation effect, and the magnetic field of a normal medical facility or research facility is reduced. It is considered that the leakage magnetic field is greatly reduced when the size of the shield room is increased. That is, if the predetermined pitch T of the conductor coil 20 is appropriately set according to the design conditions and required performance, the shaking type open magnetic shield structure of the present invention can be sufficiently put into practical use.
［実験例４］
実験例３で確認したように，磁気シールド空間１を囲む環帯状磁性板１０の各段に導線コイル２０を連続的に巻き付けた開放型磁気シールド構造５ｚは比較的大きなシェイキングノイズ（垂直成分）を漏洩することから，図１（Ａ）に示すように，環状の磁性体回路の外形（中心軸の長さ）が９５０ｍｍの環帯状磁性板１０（磁性体回路）を５段配置した開放型磁気シールド構造５ｚの各段の間隔ｄｚにそれぞれ環帯状磁性板１０と実質上同じ外形９５０ｍｍの環状導体５０を芯合わせしながら平行に挿入し，コイル駆動装置３０により導線コイル２０の各段に同じ向きのシェイキング電流Ｉ１（周波数２００Ｈｚ）を印加しながら，導体駆動装置６０により環状導体５０の各段にシェイキング電流Ｉ１と逆向きのキャンセル電流Ｉ２を印加した場合の漏洩磁場（シェイキングノイズ）を数値シミュレーションにより求める実験を行った。
[Experimental Example 4]
As confirmed in Experimental Example 3, the open type magnetic shield structure 5z in which the conductive coil 20 is continuously wound around each stage of the ring-shaped magnetic plate 10 surrounding the magnetic shield space 1 generates relatively large shaking noise (vertical component). Because of leakage, as shown in FIG. 1 (A), an open magnetic circuit in which an annular magnetic plate 10 (magnetic circuit) having an outer shape (center axis length) of 950 mm is arranged in five stages as shown in FIG. An annular conductor 50 having substantially the same outer shape 950 mm as that of the ring-shaped magnetic plate 10 is inserted in parallel with each other at intervals dz between the steps of the shield structure 5 z and aligned in the same direction in each step of the conducting coil 20 by the coil driving device 30. A canceling current I2 opposite to the shaking current I1 is applied to each stage of the annular conductor 50 by the conductor driving device 60 while applying the shaking current I1 (frequency 200 Hz). Experiments determined by numerical simulation the leakage magnetic field (shaking noise) when the Been.
本実験においても，環帯状磁性板１０の各辺（９００ｍｍ）に連続的に巻き付ける導線コイル２０の所定ピッチＴを，（ａ）１００ｍｍ，（ｂ）５０ｍｍ，（ｃ）２０ｍｍ，（ｄ）１０ｍｍと変えながら実験を繰り返した。導線コイル２０に印加するシェイキング電流Ｉ１は，実験例３の場合と同様に，（ａ）所定ピッチＴ＝１００ｍｍのときは１．４１４Ａ，（ｂ）５０ｍｍのときは０．５５９Ａ，（ｃ）２０ｍｍのときは０．２０４Ａ，（ｄ）１０ｍｍのときは０．１００Ａとした。また，環状導体５０に印加する逆向きのキャンセル電流Ｉ２は，導電コイル２０に印加するシェイキング電流Ｉ１と逆向きで同じ大きさとし，（ａ）所定ピッチＴ＝１００ｍｍのときは−１．４１４Ａ，（ｂ）５０ｍｍのときは−０．５５９Ａ，（ｃ）２０ｍｍのときは−０．２０４Ａ，（ｄ）１０ｍｍのときは−０．１００Ａに設定した。本実験の結果を，上述した実験例３の結果と共に，表１及び図１０のグラフに合わせて示す。 Also in this experiment, the predetermined pitch T of the conductive coil 20 continuously wound around each side (900 mm) of the ring-shaped magnetic plate 10 is (a) 100 mm, (b) 50 mm, (c) 20 mm, (d) 10 mm. The experiment was repeated while changing. The shaking current I1 applied to the conductor coil 20 is (a) 1.414 A when the predetermined pitch T = 100 mm, (b) 0.559 A when 50 mm, and (c) 20 mm, as in Experiment 3. In this case, it was 0.204 A, and when (d) 10 mm, it was 0.100 A. Further, the reverse cancellation current I2 applied to the annular conductor 50 has the same magnitude in the reverse direction as the shaking current I1 applied to the conductive coil 20, and (a) −1.414A when the predetermined pitch T = 100 mm, ( b) -0.559 A for 50 mm, (c) -0.204 A for 20 mm, and (d) -0.100 A for 10 mm. The result of this experiment is shown in Table 1 and the graph of FIG. 10 together with the result of Experimental Example 3 described above.
表１のキャンセル電流の漏洩磁場の平均値欄は，環状導体５０にキャンセル電流Ｉ２を印加したときの評価対象域Ｒの漏洩磁場の水平面における平均値，及び垂直面における平均値の変化をそれぞれ示す。また図１０のグラフ（キャンセル電流）は，水平面における漏洩磁場の水平成分，垂直成分，及び両者を合成した漏洩磁場の平均値の変化を表している。図１０（Ｂ）及び（Ｃ）のグラフは，環帯状磁性板１０の各段のシェイキング電流Ｉ１を流す導線コイル２０の所定ピッチＴが２０ｍｍより小さい場合に，環状導体５０に流すキャンセル電流Ｉ２によって，１段コイルのシェイキング電流Ｉ１のつくる漏洩磁場（シェイキングノイズ）を，図８の５段コイルのつくる漏洩磁場よりも小さくできることを示している。 The average value column of the leakage current of the cancellation current in Table 1 shows the change in the average value in the horizontal plane and the average value in the vertical plane of the leakage magnetic field in the evaluation target region R when the cancellation current I2 is applied to the annular conductor 50. . The graph (cancellation current) in FIG. 10 represents the horizontal component, the vertical component of the leakage magnetic field on the horizontal plane, and the change in the average value of the leakage magnetic field obtained by combining both. 10B and 10C show the cancellation current I2 that flows through the annular conductor 50 when the predetermined pitch T of the conducting coil 20 that flows the shaking current I1 of each stage of the ring-shaped magnetic plate 10 is smaller than 20 mm. , The leakage magnetic field (shaking noise) generated by the shaking current I1 of the first stage coil can be made smaller than the leakage magnetic field generated by the five stage coil of FIG.
本実験により，環帯状磁性板１０の各段の間隔ｄｚにそれぞれ実質上同径の環状導体５０を平行に挿入し，その環状導体５０にシェイキング電流と逆向きのキャンセル電流Ｉ２を流すことにより，その環状導体５０をキャンセル回路として機能させ，環帯状磁性板１０の漏洩磁場（シェイキングノイズ）を環状導体５０の発生する磁場（キャンセル磁場）により打ち消すことができることを確認できた。図１（Ａ）において環状導体５０は平面Ｐｚと平行な環状コイルであり，環状導体１０の平面Ｐｚ上で発生するキャンセル磁場は垂直成分のみであることから，垂直成分が支配的な環帯状磁性板１０のシェイキングノイズを効率的に打ち消すことができたと考えられる。 As a result of this experiment, an annular conductor 50 having substantially the same diameter is inserted in parallel to the interval dz of each step of the ring-shaped magnetic plate 10, and a canceling current I2 opposite to the shaking current is passed through the annular conductor 50, It was confirmed that the annular conductor 50 functions as a cancel circuit, and the leakage magnetic field (shaking noise) of the ring-shaped magnetic plate 10 can be canceled by the magnetic field (cancellation magnetic field) generated by the annular conductor 50. In FIG. 1A, the annular conductor 50 is an annular coil parallel to the plane Pz, and the canceling magnetic field generated on the plane Pz of the annular conductor 10 is only the vertical component. It is considered that the shaking noise of the plate 10 could be canceled efficiently.
なお，本実験では環状導体（キャンセル回路）５０の外形を環帯状磁性板１０の外形と一致させて同径としているが，環状導体５０の外形は環帯状磁性板１０の外形と厳密に一致させる必要はなく，環帯状磁性板１０の外形と実質上同径であれば，環帯状磁性板１０の導線コイル２０からの漏洩磁場（シェイキングノイズ）を環状導体５０によって十分に打ち消すことが期待できる。必要に応じて，シェイキングノイズを最も効率的に打ち消すことができるように，環帯状磁性板１０の外形（径）に対応させて環状導体５０の外形（径）を設計することも可能である。 In this experiment, the outer shape of the annular conductor (cancellation circuit) 50 is made to be the same as the outer shape of the annular belt-shaped magnetic plate 10, but the outer shape of the annular conductor 50 is exactly matched to the outer shape of the annular belt-shaped magnetic plate 10. It is not necessary, and if the outer diameter of the annular belt-shaped magnetic plate 10 is substantially the same, it can be expected that the annular conductor 50 sufficiently cancels the leakage magnetic field (shaking noise) from the conductive coil 20 of the annular belt-shaped magnetic plate 10. If necessary, the outer shape (diameter) of the annular conductor 50 can be designed in accordance with the outer shape (diameter) of the ring-shaped magnetic plate 10 so that the shaking noise can be canceled most efficiently.
［実験例５］
図１（Ａ）の開放型磁気シールド構造５ｚにおいて，図１（Ｂ）のように複数段の環状導体５０に印加するキャンセル電流Ｉ２，Ｉ３の電流値を段毎に独立に設定することにより，環帯状磁性板１０の導線コイル２０からのシェイキングノイズの漏洩を更に低減することが期待できる。すなわち，開放型磁気シールド構造内側の評価対象域Ｒの中心点におけるシェイキングノイズが最小となるように，複数段の環状導体５０に印加するキャンセル電流Ｉ２，Ｉ３を段毎に独立に最適化することができる。
[Experimental Example 5]
In the open type magnetic shield structure 5z in FIG. 1A, by setting the current values of the cancel currents I2 and I3 applied to the annular conductors 50 in a plurality of stages as shown in FIG. It can be expected that leakage of shaking noise from the conductive coil 20 of the ring-shaped magnetic plate 10 is further reduced. That is, the canceling currents I2 and I3 applied to the annular conductors 50 of the plurality of stages are optimized independently for each stage so that the shaking noise at the center point of the evaluation target area R inside the open type magnetic shield structure is minimized. Can do.
例えば，図１（Ｂ）の５段の開放型磁気シールド構造５ｚにおいて，先ず２段目，３段目，４段目の３段の環帯状磁性板１０に導線コイル２０にシェイキング電流Ｉ１を流したときの磁気シールド構造内側の中心点の磁場（シェイキングノイズ）を求める。次に，２段目，３段目の環状導体５０に逆向きのキャンセル電流Ｉ２を印加しながら，磁気シールド構造内側の中心点の磁場が打ち消されて最小（例えばゼロ）となるようなキャンセル電流Ｉ２の電流値を決定する。このようにして決定した３段モデルの結果を５段モデルに適用し，５段モデルの環帯状磁性板１０に導線コイル２０にシェイキング電流Ｉ１を流しながら，２段目，３段目の環状導体５０に逆向きのキャンセル電流Ｉ２を印加したときの磁気シールド構造内側の中心点の磁場を求める。次いで，１段目，４段目の環状導体５０に逆向きのキャンセル電流Ｉ３を印加し，磁気シールド構造内側の中心点の磁場が打ち消されて最小（例えばゼロ）となるような１段目，４段目のキャンセル電流Ｉ３の電流値を決定する。 For example, in the five-stage open type magnetic shield structure 5z shown in FIG. 1B, a shaking current I1 is first supplied to the conducting coil 20 through the second-stage, third-stage, and fourth-stage three-band annular magnetic plates 10. The magnetic field (shaking noise) at the center point inside the magnetic shield structure is obtained. Next, a canceling current that cancels the magnetic field at the center point inside the magnetic shield structure to a minimum (for example, zero) while applying a reverse canceling current I2 to the second and third annular conductors 50. The current value of I2 is determined. The results of the three-stage model determined in this way are applied to the five-stage model, and the second and third-stage annular conductors are applied while flowing the shaking current I1 through the conducting coil 20 through the ring-shaped magnetic plate 10 of the five-stage model. 50, the magnetic field at the center point inside the magnetic shield structure when the reverse cancel current I2 is applied is obtained. Next, a reverse current I3 is applied to the first and fourth annular conductors 50 so that the magnetic field at the center point inside the magnetic shield structure is canceled and minimized (for example, zero), The current value of the fourth stage cancellation current I3 is determined.
図１（Ｂ）の開放型磁気シールド構造５ｚにおいて，５段の環帯状磁性板１０に導線コイル２０にシェイキング電流Ｉ１を流しながら，環状導体５０に印加するキャンセル電流Ｉ２，Ｉ３を最適化した磁気シールド空間１の漏洩磁場を数値シミュレーションにより求める実験を行った。具体的には，（ａ）所定ピッチＴ＝１００ｍｍのときはシェイキング電流Ｉ１＝１．４１４Ａ，キャンセル電流Ｉ２＝−１．９６４Ａ，キャンセル電流Ｉ３＝−１．０９０Ａ，（ｂ）５０ｍｍのときはシェイキング電流Ｉ１＝０．５５９Ａ，キャンセル電流Ｉ２＝−０．７７７Ａ，キャンセル電流Ｉ３＝−０．４３０Ａ，（ｃ）２０ｍｍのときはシェイキング電流Ｉ１＝０．２０４Ａ，キャンセル電流Ｉ２＝−０．２８３Ａ，キャンセル電流Ｉ３＝−０．１５７Ａ，（ｄ）１０ｍｍのときはシェイキング電流Ｉ１＝０．１００Ａ，キャンセル電流Ｉ２＝−０．１３９Ａ，キャンセル電流Ｉ３＝−０．０７７Ａに設定した。本実験の結果を，上述した実験例３の結果と共に，表１及び図１０のグラフに合わせて示す。 In the open type magnetic shield structure 5z shown in FIG. 1B, the canceling currents I2 and I3 to be applied to the annular conductor 50 are optimized while the shaking current I1 is passed through the conductive coil 20 through the five-step annular magnetic plate 10. An experiment was performed to obtain the leakage magnetic field of the shield space 1 by numerical simulation. Specifically, (a) when the predetermined pitch T = 100 mm, the shaking current I1 = 1.414 A, the cancellation current I2 = −1.964 A, the cancellation current I3 = −1.090 A, and (b) the shaking when 50 mm. Current I1 = 0.559A, cancel current I2 = −0.777A, cancel current I3 = −0.430A, (c) Shaking current I1 = 0.204A, cancel current I2 = −0.283A, cancel When the current I3 = −0.157 A and (d) 10 mm, the shaking current I1 = 0.100 A, the cancel current I2 = −0.139 A, and the cancel current I3 = −0.077 A were set. The result of this experiment is shown in Table 1 and the graph of FIG. 10 together with the result of Experimental Example 3 described above.
表１のキャンセル電流（最適電流値）の漏洩磁場の平均値欄は，環状導体５０のキャンセル電流の電流値Ｉ２，Ｉ３を最適化したときの評価対象域Ｒの漏洩磁場の水平面における平均値，及び垂直面における平均値の変化をそれぞれ示している。また図１０のグラフ（キャンセル電流（最適電流値））は，水平面における漏洩磁場の水平成分，垂直成分，及び両者を合成した漏洩磁場の平均値の変化を表している。図１０（Ｂ）及び（Ｃ）のグラフは，環帯状磁性板１０の各段の間隔ｄｚにそれぞれ実質上同径の環状導体５０を芯合わせしながら平行に挿入し，その環状導体５０に最適化されたキャンセル電流Ｉ２，Ｉ３を流すことにより，１段コイルのつくる漏洩磁場を，その１段コイルの所定ピッチＴに拘わらず，図８の５段コイルのつくる漏洩磁場よりも小さくできることを示している。更に，キャンセル電流Ｉ２，Ｉ３の最適化に加えて，各段の導線コイル２０の所定ピッチＴを導線コイル２０漏洩磁場が最小となるように設定することが可能であり，導線コイル２０の所定ピッチＴを１０ｍｍ程度に小さくすることにより，所定ピッチＴが１００ｍｍの場合に比してシェイキングノイズを１／１０程度に低減できることを示している。 The mean value field of the leakage magnetic field of the cancellation current (optimum current value) in Table 1 is an average value in the horizontal plane of the leakage magnetic field in the evaluation target region R when the current values I2 and I3 of the cancellation current of the annular conductor 50 are optimized. And the change of the average value in the vertical plane. The graph (cancellation current (optimum current value)) in FIG. 10 represents the horizontal component and vertical component of the leakage magnetic field in the horizontal plane, and the change in the average value of the leakage magnetic field obtained by combining both. The graphs of FIGS. 10B and 10C show that an annular conductor 50 having substantially the same diameter is inserted in parallel with the interval dz of each step of the ring-shaped magnetic plate 10 while being aligned, and is optimal for the annular conductor 50. 8 shows that the leakage magnetic field generated by the first stage coil can be made smaller than the leakage magnetic field generated by the five-stage coil of FIG. 8 regardless of the predetermined pitch T of the first-stage coil by flowing the canceled cancellation currents I2 and I3. ing. Further, in addition to the optimization of the cancellation currents I2 and I3, the predetermined pitch T of the conductive coil 20 at each stage can be set so that the leakage magnetic field of the conductive coil 20 is minimized. It is shown that by reducing T to about 10 mm, the shaking noise can be reduced to about 1/10 compared with the case where the predetermined pitch T is 100 mm.
更に図１０（Ｂ）及び（Ｃ）は，上述した実験例３のように環状導体５０を挿入しない場合は，１段コイルの所定ピッチＴを１０ｍｍにまで小さくしても漏洩磁場を５段コイルよりも小さくすることはできない実験例３の結果を併せて示しており，実験例３と対比することにより，環帯状磁性板１０の間隔に環状導体５０を設けて最適化されたキャンセル電流Ｉ２，Ｉ３を流すことにより，環帯状磁性板１０の導線コイル２０の漏洩するシェイキングノイズを効率的に低減できることを表している。更に，１段コイルの所定ピッチＴを２０ｍｍ以下とすることにより，５段コイルの場合に比して，磁気シールド空間１へのシェイキングノイズの漏洩を１／５以下（２０％以下）に低減することができる。 Further, FIGS. 10B and 10C show that when the annular conductor 50 is not inserted as in Experimental Example 3 described above, the leakage magnetic field is reduced to 5 mm even if the predetermined pitch T of the 1-stage coil is reduced to 10 mm. The results of Experimental Example 3 that cannot be made smaller than the above are also shown. By contrasting with Experimental Example 3, an optimized canceling current I2, which is obtained by providing the annular conductor 50 in the interval between the ring-shaped magnetic plates 10 is shown. By flowing I3, it is shown that the shaking noise leaking from the conductive coil 20 of the ring-shaped magnetic plate 10 can be efficiently reduced. Furthermore, by reducing the predetermined pitch T of the 1-stage coil to 20 mm or less, the leakage of shaking noise to the magnetic shield space 1 is reduced to 1/5 or less (20% or less) compared to the case of the 5-stage coil. be able to.
なお，５段より段数の多い開放型磁気シールド構造のモデルにおいても，上述した図１（Ｂ）の最適化方法と同様にして，環状導体２０に印加するキャンセル電流の最適電流値を求めることができる。或いは，図１（Ｃ）に示すように，複数段の環状導体５０に印加するキャンセル電流をそれぞれ異なる電流値Ｉａ，Ｉｂ，Ｉｃ，Ｉｄとすることも可能である。図１（Ｃ）のモデルによれば，複数段の環帯状磁性板１０の導線コイル２０に印加するシェイキング電流が段毎に異なる場合でも，磁気シールド構造内側の中心点の磁場が最小となるようなキャンセル電流の電流値Ｉａ，Ｉｂ，Ｉｃ，Ｉｄを設定することも容易である。 Even in an open magnetic shield structure model having more than five stages, the optimum current value of the cancel current applied to the annular conductor 20 can be obtained in the same manner as the optimization method of FIG. it can. Alternatively, as shown in FIG. 1C, the cancel currents applied to the plurality of stages of annular conductors 50 can be set to different current values Ia, Ib, Ic, and Id. According to the model of FIG. 1 (C), the magnetic field at the center point inside the magnetic shield structure is minimized even when the shaking current applied to the conducting coil 20 of the annular belt-shaped magnetic plate 10 of the plurality of stages is different for each stage. It is also easy to set the current values Ia, Ib, Ic, and Id of the cancel currents.
また，図１（Ａ）〜（Ｃ）のような開放型磁気シールド構造５ｚでは，環帯状磁性板１０の複数段の間隔ｄｚに環状導体５０を配置し，その環状導体５０の一端及び他端を入出力ライン５０ａ，５０ｂに接続し，交流電源である導体駆動装置６０から入出力ライン５０ａ，５０ｂにキャンセル電流を印加しているので，入出力ライン５０ａ，５０ｂからの磁場の漏洩も問題となりうる。しかし，上述した導線コイル２０の入出力ライン２０ａ，２０ｂと同様に，導体駆動装置６０の入出力ライン５０ａ，５０ｂを隣接させて平行に配置することにより，入出力ライン５０ａ，５０ｂの発生磁場を逆向きの入出力電流によって打ち消して漏洩磁場を小さく抑えることができる。必要に応じて出力ライン５０ａ，５０ｂを撚ることにより打ち消し効果を高めることも有効である。 Further, in the open type magnetic shield structure 5z as shown in FIGS. 1A to 1C, the annular conductor 50 is arranged at a plurality of intervals dz of the ring-shaped magnetic plate 10, and one end and the other end of the annular conductor 50 are arranged. Is connected to the input / output lines 50a and 50b, and a canceling current is applied to the input / output lines 50a and 50b from the conductor drive device 60, which is an AC power supply, so that magnetic field leakage from the input / output lines 50a and 50b also becomes a problem. sell. However, similarly to the input / output lines 20a and 20b of the conductive coil 20, the input / output lines 50a and 50b of the conductor driving device 60 are arranged adjacent to each other in parallel, so that the generated magnetic fields of the input / output lines 50a and 50b are changed. The leakage magnetic field can be kept small by canceling with the reverse input / output current. It is also effective to enhance the cancellation effect by twisting the output lines 50a and 50b as necessary.
こうして本発明の目的である「シェイキングノイズの漏洩を小さく抑えることができるシェイキング式の開放型磁気シールド構造」の提供を達成できる。 Thus, it is possible to achieve the “shaking type open magnetic shield structure capable of minimizing leakage of shaking noise”, which is an object of the present invention.
図１の開放型磁気シールド構造５ｚは主にＸＹ平面の一方向又は二方向の外乱磁場の遮蔽を目的としているが，外乱磁場の方向が決まっていない磁気シールド対象空間１において三方向の外乱磁場を遮蔽対象とする場合は，図１の構造を基本ユニットとして，図１１（Ａ）〜（Ｃ）のような複数ユニットを組み合わせた開放型磁気シールド構造とすることができる。図１１は，医療施設や研究施設に設置される外寸２５５０ｍｍを基本サイズとした立方体形状の開放型磁気シールドルームの一例を示す。 The open magnetic shield structure 5z in FIG. 1 is mainly intended for shielding a disturbance magnetic field in one or two directions in the XY plane, but in a magnetic shield target space 1 in which the direction of the disturbance magnetic field is not determined, the three-way disturbance magnetic field is shown. 1 can be used as an open type magnetic shield structure in which a plurality of units as shown in FIGS. 11A to 11C are combined with the structure of FIG. 1 as a basic unit. FIG. 11 shows an example of a cube-shaped open type magnetic shield room having an outer size of 2550 mm as a basic size installed in a medical facility or research facility.
図１１（Ａ）は，磁気シールド対象空間１を貫く第１方向軸Ａｚ（Ｚ軸）と所定間隔ｄｚで交差する複数段の平行な平面Ｐｚ上にそれぞれ対象空間１を所定帯幅Ｗで囲むように環帯状磁性板１０を設けた図１と同様の開放型磁気シールド構造５ｚを示す。また，図１１（Ｂ）は磁気シールド対象空間１を貫く第２方向軸Ａｘ（Ｘ軸）と所定間隔ｄｘで交差する複数段の平行な平面Ｐｘ上にそれぞれ対象空間１を所定帯幅Ｗで囲むように環帯状磁性板１０を設けた開放型磁気シールド構造５ｘを示し，図１１（Ｃ）は磁気シールド対象空間１を貫く第３方向軸Ａｙ（Ｙ軸）と所定間隔ｄｙで交差する複数段の平行な平面Ｐｙ上にそれぞれ対象空間１を所定帯幅Ｗで囲むように環帯状磁性板１０を設けた開放型磁気シールド構造５ｙを示す。磁気シールド対象空間１の周囲に３つの開放型磁気シールド構造５ｚ，５ｘ，５ｙを入れ子状に配置し，或いは開放型磁気シールド構造５ｚ，５ｘ，５ｙのうち何れか２つを選択して入れ子状に配置して一体化することにより，三方向の外乱磁場を遮蔽する磁気シールドルームとすることできる。 FIG. 11A shows the target space 1 surrounded by a predetermined band width W on a plurality of parallel planes Pz intersecting the first direction axis Az (Z axis) penetrating the magnetic shield target space 1 at a predetermined interval dz. An open type magnetic shield structure 5z similar to that shown in FIG. 1 provided with an annular magnetic plate 10 is shown. FIG. 11B shows the target space 1 with a predetermined width W on a plurality of parallel planes Px intersecting the second direction axis Ax (X axis) penetrating the magnetic shield target space 1 at a predetermined interval dx. An open-type magnetic shield structure 5x provided with a ring-shaped magnetic plate 10 so as to surround is shown. FIG. 11C shows a plurality of crossing with a third direction axis Ay (Y axis) penetrating the magnetic shield target space 1 at a predetermined interval dy. An open type magnetic shield structure 5y is shown in which a ring-shaped magnetic plate 10 is provided so as to surround the target space 1 with a predetermined band width W on each of the parallel planes Py. Three open type magnetic shield structures 5z, 5x, 5y are arranged in a nested manner around the magnetic shield target space 1, or any two of the open type magnetic shield structures 5z, 5x, 5y are selected and nested. It is possible to provide a magnetic shield room that shields disturbance magnetic fields in three directions by arranging and integrating them.
図１１（Ａ）〜（Ｃ）の環帯状磁性板１０は，それぞれコバルト系アモルファス（厚さ２３μｍ×２０枚積層，幅５０ｍｍ）の帯板を井桁状に組んで構成し，例えば所定間隔ｄｚ＝２００ｍｍで１２段配置して開放型磁気シールド構造５ｚ，５ｘ，５ｙとすることができる。開放型磁気シールド構造５ｚ，５ｘには，同じ帯状磁性板（コバルト系アモルファス）１０で構成された扉枠１４ａ，１４ｂ，１４ｃ，１４ｄで囲まれた開口が設けられ，その開口にＰＣパーマロイ板（厚さ１ｍｍ×２枚積層）の２層（内側，外側）構造の扉１２が取り付けられている。 Each of the ring-shaped magnetic plates 10 of FIGS. 11 (A) to 11 (C) is formed by arranging strips of cobalt-based amorphous (thickness 23 μm × 20 layers, width 50 mm) in a cross-beam shape, for example, a predetermined interval dz = The open magnetic shield structures 5z, 5x, and 5y can be formed by arranging 12 stages at 200 mm. Open-type magnetic shield structures 5z and 5x are provided with openings surrounded by door frames 14a, 14b, 14c and 14d made of the same strip-shaped magnetic plate (cobalt-based amorphous) 10, and PC permalloy plates ( A door 12 having a two-layer structure (inner side and outer side) having a thickness of 1 mm × two layers is attached.
開放型磁気シールド構造５ｚ，５ｘ，５ｙの各段の環帯状磁性板１０には，図１の場合と同様にそれぞれ環状軸に沿って所定ピッチＴで導線コイル２０を巻き付け，コイル駆動装置３０により各導線コイル２０に所定周波数のシェイキング電流を印加して磁気シールド構造５ｚ，５ｘ，５ｙを磁気シェイキングする。また，環帯状磁性板１０の各段の間隔ｄｚ，ｄｘ，ｄｙにそれぞれ実質上同径の環状導体５０を平行に挿入し，導体駆動装置６０により各環状導体５０にシェイキング電流と逆向きのキャンセル電流を流すことにより，環帯状磁性板１０の漏洩磁場（シェイキングノイズ）を環状導体５０の発生する磁場（キャンセル磁場）によって打ち消す。導線コイル２０に印加するシェイキング電流の電流値及び向き，環状導体５０に印加するキャンセル電流の電流値及び向きは，設計条件及び要求性能に応じて適宜決定することができる。 As in the case of FIG. 1, the conductive coil 20 is wound around the annular axis at the predetermined pitch T along the annular axis on the annular magnetic plate 10 of each stage of the open type magnetic shield structure 5z, 5x, 5y. By applying a shaking current having a predetermined frequency to each conductive wire coil 20, the magnetic shield structures 5z, 5x, and 5y are magnetically shaken. In addition, annular conductors 50 having substantially the same diameter are inserted in parallel to the intervals dz, dx, dy of each step of the ring-shaped magnetic plate 10, and a canceling operation in the direction opposite to the shaking current is applied to each annular conductor 50 by the conductor driving device 60. By flowing a current, the leakage magnetic field (shaking noise) of the ring-shaped magnetic plate 10 is canceled by the magnetic field (cancellation magnetic field) generated by the annular conductor 50. The current value and direction of the shaking current applied to the conductor coil 20 and the current value and direction of the cancel current applied to the annular conductor 50 can be appropriately determined according to design conditions and required performance.
図１２（Ａ）は，開口のない開放型磁気シールド構造５ｙの各段の環帯状磁性板（磁性体回路）１０に１本の導線コイル２０を連続的に巻き付ける方法の一例を示す。コイル駆動装置３０のシェイキング電流は，入出力ライン２０ａ（又は２０ｂ）を介して１段目の磁性体回路の位置番号１に入力され，位置番号２〜６の順で１段目の磁性体回路を周回する。次いで，位置番号７から２段目の磁性体回路に移り，位置番号８〜１２の順で周回する。同様に１２段目の位置番号６８〜７２まで周回を繰り返したのち，位置番号７３を経由して１段目まで戻り，位置番号７４から入出力ライン２０ｂ（又は２０ａ）を介して出力される。 FIG. 12A shows an example of a method in which one conductive coil 20 is continuously wound around the ring-shaped magnetic plate (magnetic circuit) 10 of each stage of the open type magnetic shield structure 5y having no opening. The shaking current of the coil driving device 30 is input to the position number 1 of the first-stage magnetic circuit via the input / output line 20a (or 20b), and the first-stage magnetic circuit in the order of position numbers 2-6. Go around. Next, the position number 7 moves to the second-stage magnetic circuit, and the circuit circulates in the order of position numbers 8-12. Similarly, after repeating the circulation from the position number 68 to 72 of the 12th stage, the position returns to the 1st stage via the position number 73 and is output from the position number 74 via the input / output line 20b (or 20a).
図１２（Ａ）において，各段の導線コイル２０の所定ピッチＴを適切に設定することにより，各段の磁性体回路のシェイキングノイズを低減することができる。各段のシェイキング電流を最適化する場合は，電流値自体を段毎に変えることはできないが，各段の所定ピッチＴ（ターン数）を調整することで実質的に対応できる。各段の磁性体回路からのシェイキングノイズと共に，隣接する磁性体回路に移行する経路でのシェイキングノイズの漏洩も懸念されるが，これについては入出力ライン２０ａ，２０ｂと同様に，位置番号７，１３，１９，２５，３１，３７，４３，４９，５５，６１，６７と位置番号７３とは電流値が同じで方向が逆のため，隣接させて平行に配置することにより逆向き電流によって互いに打ち消して漏洩を小さく抑えることができる。必要に応じて両者を撚ることにより打ち消し効果を高めることも有効である。 In FIG. 12A, by appropriately setting the predetermined pitch T of the conductive coil 20 at each stage, the shaking noise of the magnetic circuit at each stage can be reduced. When the shaking current of each stage is optimized, the current value itself cannot be changed for each stage, but it can be substantially handled by adjusting the predetermined pitch T (number of turns) of each stage. In addition to the shaking noise from the magnetic circuit at each stage, there is a concern about leakage of the shaking noise in the path that moves to the adjacent magnetic circuit. However, as with the input / output lines 20a and 20b, the position number 7, 13, 19, 25, 31, 37, 43, 49, 55, 61, 67 and position number 73 have the same current value and opposite directions. It can be canceled out and leakage can be kept small. It is also effective to enhance the cancellation effect by twisting the two as necessary.
また図１２（Ｂ）は，開放型磁気シールド構造５ｙの各段の間隙ｄｙに１本の環状導体（キャンセル回路）５０を連続的に配置する方法の一例を示す。導体駆動装置６０のキャンセル電流は，入出力ライン５０ａ（又は５０ｂ）を介して１段目のキャンセル回路の位置番号１に入力され，位置番号２〜６の順で１段目のキャンセル回路を周回する。キャンセル電流は，シェイキング電流とは逆向きである。次いで，位置番号７から２段目のキャンセル回路に移り，位置番号７〜１２の順で周回する。同様に１１段目の位置番号５２〜５６まで周回を繰り返したのち，位置番号５７を経由して１段目のキャンセル回路まで戻り，位置番号５８から入出力ライン５０ｂ（又は５０ａ）を介して出力される。 FIG. 12B shows an example of a method in which one annular conductor (cancel circuit) 50 is continuously arranged in the gap dy of each stage of the open type magnetic shield structure 5y. The cancel current of the conductor driving device 60 is input to the position number 1 of the first-stage cancel circuit via the input / output line 50a (or 50b), and goes around the first-stage cancel circuit in the order of position numbers 2-6. To do. The cancellation current is in the opposite direction to the shaking current. Next, the process proceeds from the position number 7 to the second-stage cancel circuit, and circulates in the order of the position numbers 7-12. Similarly, after repeating the laps to the 11th stage position numbers 52 to 56, the position number 57 is returned to the first stage cancel circuit, and the position number 58 is output via the input / output line 50b (or 50a). Is done.
図１２（Ｂ）において，各段のキャンセル電流を最適化する場合は，図１（Ｂ）と同様に複数段のキャンセル回路をグループ分けして別々の導体駆動装置６０を設け，又は図１（Ｃ）と同様に段毎のキャンセル回路に別々の導体駆動装置６０を設けることができる。隣接するキャンセル回路に移行する経路での磁場の漏洩も懸念されるが，これについては入出力ライン５０ａ，５０ｂと同様に，位置番号６〜７，１１〜１２，１６〜１７，２１〜２２，２６〜２７，３１〜３２，３６〜３７，４１〜４２，４６〜４７，５１〜５２と位置番号５７とは電流値が同じで方向が逆のため，接近させて平行に設置することにより逆向き電流によって互いに打ち消して漏洩磁場を小さく抑えることができる。必要に応じて両者を撚ることにより打ち消し効果を高めることも有効である。 12B, in order to optimize the cancel current of each stage, a plurality of stages of cancel circuits are grouped as in FIG. 1B, and separate conductor driving devices 60 are provided, or FIG. As in C), a separate conductor driving device 60 can be provided in the cancel circuit for each stage. There is also a concern about leakage of the magnetic field in the path moving to the adjacent cancel circuit. However, as with the input / output lines 50a and 50b, the position numbers 6 to 7, 11 to 12, 16 to 17, 21 to 22, 26-27, 31-32, 36-37, 41-42, 46-47, 51-52 and position number 57 have the same current value and reverse direction, so they are reversed by being placed in parallel and close to each other. The leakage magnetic field can be kept small by canceling each other by the direction current. It is also effective to enhance the cancellation effect by twisting the two as necessary.
図１３（Ａ）は，開口のある開放型磁気シールド構造５ｚの各段の環帯状磁性板１０に１本の導線コイル２０を連続的に巻き付ける方法の一例を示す。シェイキング電流は，入出力ライン２０ａ（又は２０ｂ）を介して１段目の磁性体回路の位置番号１に入力され，位置番号２〜７を周回する。次いで，位置番号８から２段目の磁性体回路に移って位置番号９に至り，ここで扉１２により流れを遮られた電流は，扉枠１４ａ，１４ｄ，１４ｂの位置番号１０〜１２を介して迂回したのち位置番号１３〜１７の順で周回し，位置番号１８を介して３段目の磁性体回路に移る。同様に１１段目の位置番号９９から扉枠１４ａ，１４ｃ，１４ｂの位置番号１００〜１０２を迂回して位置番号１０３〜１０７まで周回を繰り返したのち，位置番号１０８から１２段目の磁性体回路に移る。更に，位置番号１０９〜１１４の順で巡回したのち，位置番号１１５を介して１段目まで戻り，位置番号１１６から入出力ライン２０ｂ（又は２０ａ）を介して出力される。 FIG. 13A shows an example of a method in which one conductive coil 20 is continuously wound around the ring-shaped magnetic plate 10 at each stage of the open magnetic shield structure 5z having an opening. The shaking current is inputted to the position number 1 of the first-stage magnetic circuit circuit via the input / output line 20a (or 20b) and goes around the position numbers 2 to 7. Next, the position number 8 moves to the magnetic circuit of the second stage to reach the position number 9, where the current blocked by the door 12 passes through the position numbers 10 to 12 of the door frames 14a, 14d and 14b. After detouring, the circuit circulates in the order of position numbers 13 to 17, and moves to the third-stage magnetic circuit via position number 18. Similarly, the position number 99 from the 11th stage bypasses the position numbers 100 to 102 of the door frames 14a, 14c, and 14b and repeats the circulation from the position numbers 103 to 107, and then the magnetic circuit of the 12th stage from the position number 108. Move on. Further, after circulating in the order of the position numbers 109 to 114, it returns to the first stage via the position number 115 and is output from the position number 116 via the input / output line 20b (or 20a).
図１３（Ａ）において，隣接する磁性体回路間を移行する経路のシェイキングノイズの漏洩は，位置番号８，１８，２８，３８，４８，５８，６８，７８，８８，９８，１０８と位置番号１１５とは電流値が同じで方向が逆であるため，隣接させて平行に配置することにより逆向き電流によって互いに打ち消して漏洩を小さく抑えることができる。必要に応じて両者を撚ることにより打ち消し効果を高めることも有効である。なお，図１３（Ａ）においてシェイキング電流の扉１２の迂回方向は，距離が短い方となる。 In FIG. 13A, the leakage of the shaking noise in the path moving between adjacent magnetic circuits is the position numbers 8, 18, 28, 38, 48, 58, 68, 78, 88, 98, 108 and the position numbers. Since the current value is the same as that of 115 and the direction is opposite, by arranging them adjacent to each other in parallel, they can cancel each other out by the reverse current and suppress leakage. It is also effective to enhance the cancellation effect by twisting the two as necessary. In FIG. 13A, the detour direction of the door 12 with the shaking current is the shorter distance.
また図１３（Ｂ）は，開放型磁気シールド構造５ｚの各段の間隙ｄｚに１本の環状導体（キャンセル回路）５０を連続的に配置する方法の一例を示す。キャンセル電流は，入出力ライン５０ａ（又は５０ｂ）を介して１段目のキャンセル回路の位置番号１に入力され，位置番号２から位置番号３に至り，ここで扉１２により流れを遮られた電流は，扉枠１４ａ，１４ｄ，１４ｂの位置番号４〜６を介して迂回したのち位置番号７〜１１の順で周回する。キャンセル電流は，シェイキング電流とは逆向きである。次いで，位置番号１２から２段目のキャンセル回路に移って位置番号１３に至り，ここで扉１２により流れを遮られた電流は，扉枠１４ａ，１４ｄ，１４ｂの位置番号１４〜１６を介して迂回したのち位置番号１７〜２１の順で周回する。同様に位置番号１２から１１段目のキャンセル回路に移って位置番号１０３に至り，ここで扉１２により流れを遮られた電流は，扉枠１４ａ，１４ｃ，１４ｂの位置番号１０４〜１０６を介して迂回したのち位置番号１０７〜１１１の順で周回する。 FIG. 13B shows an example of a method in which one annular conductor (cancellation circuit) 50 is continuously arranged in the gap dz of each stage of the open type magnetic shield structure 5z. The cancel current is input to the position number 1 of the first-stage cancel circuit via the input / output line 50a (or 50b) and reaches the position number 3 from the position number 2 where the flow is blocked by the door 12 here. Circulates in the order of position numbers 7 to 11 after detouring via the position numbers 4 to 6 of the door frames 14a, 14d and 14b. The cancellation current is in the opposite direction to the shaking current. Next, the position number 12 shifts to the cancellation circuit in the second stage to reach the position number 13, where the current blocked by the door 12 passes through the position numbers 14-16 of the door frames 14a, 14d, 14b. After detouring, go around in order of position number 17-21. Similarly, the position number 12 shifts to the eleventh stage cancel circuit to reach the position number 103, where the current blocked by the door 12 passes through the position numbers 104 to 106 of the door frames 14a, 14c and 14b. After detouring, it circulates in the order of position numbers 107-111.
図１３（Ｂ）において，キャンセル電流の扉１２の迂回方向も，距離が短い方となる。１１段目のキャンセル回路は，位置番号１１１から位置番号１１２を介して１段目まで戻り，位置番号１１３から入出力ライン５０ｂ（又は５０ａ）を介して出力される。隣接するキャンセル回路に移行する経路での磁場の漏洩は，位置番号１１〜１２，２１〜２２，３１〜３２，４１〜４２，５１〜５２，６１〜６２，７１〜７２，８１〜８２，９１〜９２，１０１〜１０２と位置番号１１２とは電流値が同じで方向が逆のため，接近させて平行に設置することにより逆向き電流によって互いに打ち消して漏洩磁場を小さく抑えることができる。必要に応じて両者を撚ることにより打ち消し効果を高めることも有効である。 In FIG. 13B, the detour direction of the cancellation current door 12 is also the shorter one. The eleventh stage cancel circuit returns from the position number 111 to the first stage via the position number 112 and is output from the position number 113 via the input / output line 50b (or 50a). The leakage of the magnetic field in the path to the adjacent cancel circuit is the position numbers 11 to 12, 21 to 22, 31 to 32, 41 to 42, 51 to 52, 61 to 62, 71 to 72, 81 to 82, 91. Since .about.92, 101.about.102 and position number 112 have the same current value and opposite directions, they can be placed close to each other in parallel to cancel each other out by a reverse current and suppress the leakage magnetic field to be small. It is also effective to enhance the cancellation effect by twisting the two as necessary.
図１３（Ｃ）〜（Ｆ）は，隣接する磁性体回路への移行経路となる扉枠１４ｃ，１４ａ，１４ｂ，１４ｄのシェイキング電流及びキャンセル電流をまとめて示したものである。図１３（Ｃ）の扉枠１４ｃでは，位置符号６１，７１，８１，９１，１０１（シェイキング電流）は右向きであり，位置番号６５，７５，８５，９５，１０５（キャンセル電流）は左向きであるから，これらを合成するとゼロとなる。図１３（Ｆ）の扉枠１４ｄでは，位置符号１１，２１，３１，４１，５１（シェイキング電流）は右向きであり，位置番号５，１５，２５，３５，４５，５５（キャンセル電流）は左向きであるから，これらを合成すると左向き電流が単独で存在することになる。 FIGS. 13C to 13F collectively show shaking currents and canceling currents of the door frames 14c, 14a, 14b, and 14d that are transition paths to adjacent magnetic circuits. In the door frame 14c of FIG. 13C, the position codes 61, 71, 81, 91, 101 (shaking current) are directed to the right, and the position numbers 65, 75, 85, 95, 105 (cancellation current) are directed to the left. Therefore, when these are combined, it becomes zero. In the door frame 14d in FIG. 13F, the position codes 11, 21, 31, 41, 51 (shaking current) are directed to the right, and the position numbers 5, 15, 25, 35, 45, 55 (cancellation current) are directed to the left. Therefore, when these are combined, a leftward current exists alone.
また，図１３（Ｄ）の扉枠１４ａでは，位置番号６０，７０，８０，９０，１００（シェイキング電流）と，位置番号６，１６，２６，３６，４６，５６（キャンセル電流）は上向きであり，位置番号１０，２０，３０，４０，５０（シェイキング電流）と，位置番号６６，７６，８６，９６，１０６（キャンセル電流）は下向きであるから，これらを合成すると上向き電流が１段おきに単独で存在する。更に図１３（Ｅ）の窓枠１４ｂでは，位置番号１２，２２，３２，４２，５２（シェイキング電流）と，位置番号６４，７４，８４，９４，１０４（キャンセル電流）は上向きであり，位置番号６２，７２，８２，９２，１０２（シェイキング電流）と，位置番号４，１４，２４，３４，４４，５４（キャンセル電流）は下向きであるから，これらを合成すると下向き電流が１段おきに単独で存在する。 Further, in the door frame 14a of FIG. 13D, the position numbers 60, 70, 80, 90, 100 (shaking current) and the position numbers 6, 16, 26, 36, 46, 56 (cancellation current) are upward. Yes, position numbers 10, 20, 30, 40, 50 (shaking current) and position numbers 66, 76, 86, 96, 106 (cancellation current) are downwards. Exist alone. Further, in the window frame 14b of FIG. 13E, the position numbers 12, 22, 32, 42, 52 (shaking current) and the position numbers 64, 74, 84, 94, 104 (cancellation current) are facing upward, Since the numbers 62, 72, 82, 92, 102 (shaking current) and the position numbers 4, 14, 24, 34, 44, 54 (cancellation current) are downward, when these are combined, the downward current is every other stage. Exists alone.
このように扉枠１４ａ，１４ｂ，１４ｄにおいて逆向き電流によって打ち消すことができない電流が存在しており，これらの経路から磁場（シェイキングノイズ）の漏洩が懸念される。そのため，図１３（Ｇ）及び（Ｈ）に示すように，扉枠１４ａ，１４ｂ，１４ｄに沿って例えばＰＣパーマロイ製のスリット２３付き磁気シールド筒体２２（角筒又は円筒）を設置し，その筒体２２内に隣接する回路への移行経路部分を収容することが望ましい。スリット２３は，シールド筒体２２の長手方向に沿って設けられており，単線の導線コイル２０からの磁場の漏洩方向を制御する機能を有し，シールド対象空間１と反対側に向けることで対象空間１へのシェイキングノイズの漏洩を低減する（特許文献５参照）。スリット２３は，導線コイル２０及び環状導体５０の引き入れ，引き出しの際にも利用できる。なお，シェイキング電流及びキャンセル電流の電流値を最適化した場合は，段毎に電流値が相違するために隣接する回路への移行経路部分で逆向き電流の打ち消し効果が低下しうるが，そのような場合にもスリット２３付き磁気シールド筒体２２に移行経路部分を収容することで漏洩磁場を抑えることができる。 As described above, there is a current that cannot be canceled by the reverse current in the door frames 14a, 14b, and 14d, and there is a concern about leakage of a magnetic field (shaking noise) from these paths. Therefore, as shown in FIGS. 13 (G) and 13 (H), a magnetic shield cylinder 22 (square tube or cylinder) with a slit 23 made of, for example, PC Permalloy is installed along the door frames 14a, 14b, 14d. It is desirable to accommodate a transition path portion to an adjacent circuit in the cylindrical body 22. The slit 23 is provided along the longitudinal direction of the shield cylinder 22, has a function of controlling the leakage direction of the magnetic field from the single wire conductor coil 20, and is directed to the opposite side to the shield target space 1. The leakage of shaking noise to the space 1 is reduced (see Patent Document 5). The slit 23 can also be used when the lead coil 20 and the annular conductor 50 are drawn in and pulled out. Note that when the current values of the shaking current and the cancellation current are optimized, the current value is different for each stage, so that the reverse current canceling effect may be reduced at the transition path part to the adjacent circuit. Even in this case, the leakage magnetic field can be suppressed by accommodating the transition path portion in the magnetic shield cylinder 22 with the slit 23.
１…磁気シールド対象空間 ２…帯状磁性板
３…シールド簾体 ５…開放型磁気シールド構造
８…磁気センサ ９…端縁（重ね合わせ部）
１０…環帯状磁性板 １２…扉
１４ａ，１４ｂ，１４ｃ，１４ｄ…扉枠
２０…導線コイル ２０ａ，２０ｂ…入出力ライン
２２…シールド筒体 ２３…スリット
３０…コイル駆動装置
４０…磁気シールド部材 ４１…基材
４２ａ，４２ｂ…磁性薄帯 ４３…導線コイル（シェイキングコイル）
４４…入力端子 ４５…出力端子
５０…環状導体 ５０ａ，５０ｂ…入出力ライン
６０…導体駆動装置
Ａｘ，Ａｙ，Ａｚ…軸 ｄ…間隔
Ｉ…電流 Ｌ…電流担体（コイル）
Ｍ…外乱磁場 Ｏ…中心点
Ｐｘ，Ｐｙ，Ｐｚ…平面 Ｒ…評価対象域
Ｔ…ピッチ Ｗ…環帯状磁性板の帯幅
DESCRIPTION OF SYMBOLS 1 ... Magnetic shield object space 2 ... Strip | belt-shaped magnetic board 3 ... Shield housing 5 ... Open type magnetic shield structure 8 ... Magnetic sensor 9 ... Edge (overlapping part)
DESCRIPTION OF SYMBOLS 10 ... Ring-shaped magnetic plate 12 ... Door 14a, 14b, 14c, 14d ... Door frame 20 ... Conductor coil 20a, 20b ... Input / output line 22 ... Shield cylinder 23 ... Slit 30 ... Coil drive device 40 ... Magnetic shield member 41 ... Base material 42a, 42b ... Magnetic ribbon 43 ... Conductor coil (shaking coil)
44 ... input terminal 45 ... output terminal 50 ... annular conductors 50a, 50b ... input / output lines 60 ... conductor drive devices Ax, Ay, Az ... axes d ... interval I ... current L ... current carrier (coil)
M ... disturbance magnetic field O ... center point Px, Py, Pz ... plane R ... evaluation target area T ... pitch W ... band width of ring-shaped magnetic plate
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| JP2016016784A JP6599258B2 (en) | 2016-01-31 | 2016-01-31 | Shaking type open magnetic shield structure |
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| JP2016016784A JP6599258B2 (en) | 2016-01-31 | 2016-01-31 | Shaking type open magnetic shield structure |
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| JP2017135354A JP2017135354A (en) | 2017-08-03 |
| JP6599258B2 true JP6599258B2 (en) | 2019-10-30 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPH03161998A (en) * | 1989-11-21 | 1991-07-11 | Kosuke Harada | Plane coil |
| JP2004179550A (en) * | 2002-11-28 | 2004-06-24 | Sangaku Renkei Kiko Kyushu:Kk | Split type cylindrical magnetic shield apparatus |
| JP2005217341A (en) * | 2004-02-02 | 2005-08-11 | Kri Inc | Environmental magnetism noise shielding equipment |
| JP4354898B2 (en) * | 2004-11-08 | 2009-10-28 | 新日本製鐵株式会社 | Magnetic shield structure for AC power single wire cable |
| JP4794353B2 (en) * | 2006-05-17 | 2011-10-19 | 新日本製鐵株式会社 | Magnetic shield structure and magnetic shield method |
| JP5328599B2 (en) * | 2009-10-09 | 2013-10-30 | 鹿島建設株式会社 | Composite magnetic shield structure and system |
| JP5930400B2 (en) * | 2012-10-26 | 2016-06-08 | 鹿島建設株式会社 | Open magnetic shield structure with conductor circuit |
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