JP5592193B2 - Method of constructing a composite magnetic shield for disturbance magnetic fields - Google Patents
Method of constructing a composite magnetic shield for disturbance magnetic fields Download PDFInfo
- Publication number
- JP5592193B2 JP5592193B2 JP2010184215A JP2010184215A JP5592193B2 JP 5592193 B2 JP5592193 B2 JP 5592193B2 JP 2010184215 A JP2010184215 A JP 2010184215A JP 2010184215 A JP2010184215 A JP 2010184215A JP 5592193 B2 JP5592193 B2 JP 5592193B2
- Authority
- JP
- Japan
- Prior art keywords
- magnetic
- magnetic field
- shield
- cylindrical
- target position
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 230000005291 magnetic effect Effects 0.000 title claims description 434
- 239000002131 composite material Substances 0.000 title claims description 26
- 238000000034 method Methods 0.000 title claims description 6
- 238000010276 construction Methods 0.000 claims description 16
- 238000000926 separation method Methods 0.000 claims description 10
- 230000004323 axial length Effects 0.000 claims description 4
- 238000009826 distribution Methods 0.000 description 23
- 230000005294 ferromagnetic effect Effects 0.000 description 15
- 238000005259 measurement Methods 0.000 description 12
- 230000004907 flux Effects 0.000 description 9
- 230000006866 deterioration Effects 0.000 description 8
- 230000035699 permeability Effects 0.000 description 8
- 230000010363 phase shift Effects 0.000 description 6
- 238000012546 transfer Methods 0.000 description 6
- 238000002474 experimental method Methods 0.000 description 5
- 230000002238 attenuated effect Effects 0.000 description 4
- 230000006698 induction Effects 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 3
- 230000015556 catabolic process Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000006731 degradation reaction Methods 0.000 description 3
- 238000006073 displacement reaction Methods 0.000 description 3
- 238000009434 installation Methods 0.000 description 3
- 229910000889 permalloy Inorganic materials 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000010894 electron beam technology Methods 0.000 description 2
- 230000005389 magnetism Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000012827 research and development Methods 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 230000005415 magnetization Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
Landscapes
- Measuring Magnetic Variables (AREA)
- Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
Description
本発明は外乱磁場の複合型磁気シールド構築方法に関し、とくにパッシブ型磁気シールドとアクティブ型磁気シールドとを組み合わせて外乱磁場を減衰させる複合型磁気シールドを構築する方法に関する。 The present invention relates to a composite magnetic shield construction method for a disturbance magnetic field, and more particularly to a method for constructing a composite magnetic shield that attenuates a disturbance magnetic field by combining a passive magnetic shield and an active magnetic shield.
半導体製造施設で用いる電子顕微鏡、ＥＢ露光装置、ＥＢステッパ等の電子ビーム応用装置は、例えば１００ｎＴ（１ｍＧ）程度の微弱な磁気ノイズでも電子ビームの軌道が変化するので、製品の品質を維持するために外乱磁場（環境磁場）の影響を避けることが必要である。また、医療施設等で用いるＭＲＩ装置、ＮＭＲ装置、脳磁計や心磁計等のＳＱＵＩＤ（超電導量子干渉素子）応用装置も、超微弱な磁場変動への感度が高いために外乱磁場の影響を遮断することが求められる。このような磁場の影響を受けやすい装置（嫌磁気装置）を外乱磁場から保護して正常な動作を保証するため、半導体製造施設・医療施設等の内部に磁気シールド空間（磁気シールドルーム）を設けることがある。 Electron beam application devices such as electron microscopes, EB exposure devices, and EB steppers used in semiconductor manufacturing facilities change the electron beam trajectory even with weak magnetic noise of about 100 nT (1 mG), for example, to maintain product quality. It is necessary to avoid the influence of disturbance magnetic field (environmental magnetic field). In addition, SQUID (superconducting quantum interference device) application devices such as MRI devices, NMR devices, magnetoencephalographs and magnetocardiographs used in medical facilities etc. are also highly sensitive to very weak magnetic field fluctuations, and thus block the influence of disturbance magnetic fields. Is required. In order to protect such devices (aerodynamic devices) that are susceptible to magnetic fields from disturbance magnetic fields and to ensure normal operation, magnetic shield spaces (magnetic shield rooms) are provided inside semiconductor manufacturing facilities and medical facilities. Sometimes.
磁気シールド空間は、例えば比透磁率μの高いパーマロイ、電磁鋼板等の強磁性板で空間の周囲を覆い、空間外から到来する外乱磁場（以下、到来外乱磁場という）の磁力線を磁性板料中に迂回させて空間内への進入を防ぐパッシブ型（受動型）構造として構築することができる。ただし、高性能な磁気シールド空間を構築する場合、強磁性板を適当な空隙を設けて多層配置する必要が生じ、コストが膨大になる等の問題点がある。これに対し、空間の内側又は外側に補償磁場発生用のコイル（以下、補償コイルということがある）を配置し、到来外乱磁場の変動に応じて補償コイルに適切な補償磁場を発生させて到来外乱磁場の変動を減衰させ又は相殺するアクティブ型（能動型）の磁気シールド構造が開発されている（例えば特許文献１参照）。微弱な到来外乱磁場の変動に対応した磁気シールドの構築にはパッシブ型とアクティブ型とを組み合わせた複合型磁気シールドが性能的・経済的に有利であり、複合型磁気シールド構造の高性能化を図る研究開発が進められている（非特許文献１、２参照）。 The magnetic shield space, for example, covers the space with a ferromagnetic plate such as permalloy with high relative permeability μ, magnetic steel plate, etc., and the magnetic field lines of disturbance magnetic field coming from outside the space (hereinafter referred to as incoming disturbance magnetic field) It can be constructed as a passive type (passive type) structure that detours to prevent entry into the space. However, when constructing a high-performance magnetic shield space, there is a problem that the ferromagnetic plates need to be arranged in multiple layers with appropriate gaps, resulting in a huge cost. On the other hand, a coil for generating a compensation magnetic field (hereinafter sometimes referred to as a compensation coil) is arranged inside or outside the space, and an appropriate compensation magnetic field is generated in the compensation coil in accordance with fluctuations in the incoming disturbance magnetic field. An active type magnetic shield structure that attenuates or cancels fluctuations in a disturbance magnetic field has been developed (see, for example, Patent Document 1). For the construction of a magnetic shield that responds to weak fluctuations in the incoming disturbance magnetic field, a composite magnetic shield combining a passive type and an active type is advantageous in terms of performance and economy. Research and development is underway (see Non-Patent Documents 1 and 2).
非特許文献２は、図８（Ａ）のような複合型磁気シールド構造１を開示している。図示例の複合型構造１は、シールド対象空間Ｒの床、壁、天井の各内面に強磁性板（パーマロイ等）６ａ、６ｂ、６ｃ、６ｄを隙間なく配置したパッシブ型磁気シールド構造７（以下、密閉型シールド構造７ということがある）と、アクティブ型磁気シールド構造１０とを組み合わせたものである。図示例のアクティブ型磁気シールド構造１０は、空間Ｒの内側又は外側に配置した補償コイル１２ａ、１２ｂと、磁気センサ（磁気検出器）１４と、磁気センサ１４の計測磁場（磁束密度）を入力して補償コイル１２ａ、１２ｂを駆動する制御装置１６とにより構成されている。例えば空間Ｒ内の所定位置ＰのＸ軸に補償コイル１２ａ、１２ｂの中心軸線を芯合わせして配置し、パッシブ型磁気シールド７だけでは対応できないＸ軸方向の到来外乱磁場Ｂｏによる空間Ｒ内の動的な磁場変動（後述する所定位置Ｐの内側磁場Ｂｅ）を補償コイル１２ａ、１２ｂの発生する補償磁場Ｂｃの重畳によって減衰させる。図示例はＸ軸方向の補償コイル１２ａ、１２ｂのみを示しているが、Ｙ軸方向及びＺ軸方向についても同様に補償コイル１２を配置することにより、あらゆる方向の到来外乱磁場に対応することができる。 Non-Patent Document 2 discloses a composite magnetic shield structure 1 as shown in FIG. The composite type structure 1 in the illustrated example is a passive type magnetic shield structure 7 (hereinafter referred to as “ferromagnetic plates” 6a, 6b, 6c, and 6d arranged without gaps on the inner surfaces of the floor, wall, and ceiling of the shielded space R. , Sometimes referred to as a sealed shield structure 7) and an active magnetic shield structure 10. The active magnetic shield structure 10 in the illustrated example inputs compensation coils 12a and 12b disposed inside or outside the space R, a magnetic sensor (magnetic detector) 14, and a measurement magnetic field (magnetic flux density) of the magnetic sensor 14. And a control device 16 for driving the compensation coils 12a and 12b. For example, the center axis of the compensation coils 12a and 12b is aligned with the X axis at a predetermined position P in the space R, and the space R due to the incoming disturbance magnetic field Bo in the X axis direction that cannot be handled by the passive magnetic shield 7 alone. A dynamic magnetic field fluctuation (an inner magnetic field Be at a predetermined position P described later) is attenuated by superposition of the compensation magnetic field Bc generated by the compensation coils 12a and 12b. In the illustrated example, only the compensation coils 12a and 12b in the X-axis direction are shown. However, by arranging the compensation coil 12 in the same manner in the Y-axis direction and the Z-axis direction, it is possible to deal with incoming disturbance magnetic fields in all directions. it can.
また非特許文献２は、図８（Ａ）のような複合型構造において、アクティブ型（補償コイル１２）とパッシブ型（強磁性板６）との配置関係によるシールド性能を比較検討し、強磁性板６の内側に補償コイル１２を配置して複合型構造とする方が、強磁性板６の外側に補償コイル１２を配置する構造に比して、高いシールド性能を効率よく得ることができると報告している。例えば、強磁性板６の内側の高さ１／２の位置に１．０５〜１．１ｍ間隔で一対の補償コイル１２ａ、１２ｂを配置すれば、比較的小さな電流でＸ軸方向の到来外乱磁場を減衰させることができ、対象空間Ｒの中心付近に比較的広い低磁場領域を形成することができる。また、パッシブ型の内側に補償コイル１２を配置する複合型構造は、補償コイル１２の発生する補償磁場が空間Ｒの周辺環境に磁気ノイズとなって拡散するおそれがなく、パッシブ型の強磁性板６の磁化過程に起因するような磁気ノイズにも対応できる点でも有利であると指摘している。 Non-Patent Document 2 compares the shielding performance depending on the arrangement relationship between the active type (compensation coil 12) and the passive type (ferromagnetic plate 6) in the composite structure as shown in FIG. When the compensation coil 12 is disposed inside the plate 6 to form a composite structure, a higher shield performance can be obtained more efficiently than the structure in which the compensation coil 12 is disposed outside the ferromagnetic plate 6. Reporting. For example, if a pair of compensation coils 12a and 12b are arranged at a height of 1/2 on the inner side of the ferromagnetic plate 6 at intervals of 1.05 to 1.1 m, an incoming disturbance magnetic field in the X-axis direction with a relatively small current. Can be attenuated, and a relatively wide low magnetic field region can be formed near the center of the target space R. Further, the composite structure in which the compensation coil 12 is arranged inside the passive type does not cause the compensation magnetic field generated by the compensation coil 12 to diffuse into the surrounding environment of the space R as magnetic noise, and the passive type ferromagnetic plate. It is pointed out that it is advantageous in that it can cope with magnetic noise caused by the magnetization process of No. 6.
しかし、図８（Ａ）の複合型磁気シールド構造は、シールド対象空間Ｒ内のシールド対象位置Ｐと磁気センサ１４の設置位置Ｓ（センサ位置Ｓ）とが離れていると、シールド性能が劣化しうる問題点がある。アクティブ型磁気シールドでは、センサ位置Ｓの磁場（制御信号）に基づいて対象位置Ｐの磁場（出力信号）を制御するフィードバック系（図８（Ｂ）参照）を用いるために、センサ位置Ｓを対象位置Ｐにできるだけ近付けることが望ましいが、現実には対象位置Ｐにシールド対象の嫌磁気装置（例えばＭＲＩ装置等）が設置されるので、様々な物理的干渉を回避するためにセンサ位置Ｓと対象位置Ｐとを離さざるを得ないことも多い。例えば、強磁場を発生する嫌磁気装置（例えばＭＲＩ装置のデュワ部）の近傍では微弱な磁場の変動を計測すること自体が難しいため磁気センサ１４を装置から隔てて設置しなければならず、また装置利用者のハンドリング等の観点から嫌磁気装置の近傍にセンサの設置スペースを確保できない場合もある。例えばＭＲＩ装置を設置する磁気シールド空間Ｒ（シールド室）では、磁気センサ１４をＭＲＩ装置から十分に離れた天井面等に設置することも通常である。 However, in the composite magnetic shield structure of FIG. 8A, when the shield target position P in the shield target space R and the installation position S (sensor position S) of the magnetic sensor 14 are separated, the shield performance deteriorates. There are possible problems. The active magnetic shield uses a feedback system (see FIG. 8B) that controls the magnetic field (output signal) at the target position P based on the magnetic field (control signal) at the sensor position S. Although it is desirable to be as close as possible to the position P, in reality, a shielded anaerobic device (for example, an MRI apparatus) is installed at the target position P. Therefore, in order to avoid various physical interferences, the sensor position S and the target In many cases, the position P must be separated. For example, since it is difficult to measure weak magnetic field fluctuations in the vicinity of a magnetoless device that generates a strong magnetic field (for example, the dewar part of an MRI device), the magnetic sensor 14 must be installed separately from the device. In some cases, the installation space of the sensor cannot be secured in the vicinity of the negative magnetic device from the viewpoint of handling of the user of the device. For example, in the magnetic shield space R (shield room) in which the MRI apparatus is installed, it is usual to install the magnetic sensor 14 on a ceiling surface or the like sufficiently away from the MRI apparatus.
図８（Ａ）において、センサ位置Ｓと対象位置Ｐとが離れているとシールド性能の劣化を招く原因の１つは、シールド対象空間Ｒの内部の各位置における磁場Ｂｅ（以下、内部磁場Ｂｅということがある）に位相差δが生じることにある。すなわち、一般にパッシブ型磁気シールドでは到来外乱磁場Ｂｏの磁束密度φが変化すると強磁性板（導体）６中に起電力ｅ（＝−ｄφ／ｄｔ）の渦電流が誘導され、図示例のように対象空間Ｒの内面全体を強磁性板６で覆う密閉型シールド構造７では、到来外乱磁場Ｂｏの方向に応じて各内面の強磁性板６に向きの異なる渦電流が流れることにより内部磁場Ｂｅを減衰させる。例えば図６（Ａ）及び図６（Ｂ）に示すようにＸ軸方向の到来外乱磁場Ｂｏの磁束密度φが変化すると、空間ＲのＸ軸方向と交差する前後ＹＺ面の強磁性板６の外周部で電流密度が高くなり、その渦電流に起因して発生する誘導磁場と到来外乱磁場Ｂｏとが合成される結果、前後ＹＺ面の内部磁場Ｂｅは外側の到来外乱磁場Ｂｏに対して位相がずれる。また、空間ＲのＸ軸方向と平行な上下ＸＺ面の強磁性板６でも電流密度が高くなり、同様に上下ＸＺ面の内部磁場Ｂｅに位相のずれを生じさせるが、上下ＸＺ面の内側の渦電流に起因して発生する誘導磁場は前後ＹＺ面の場合とは極性が異なる。このように、空間Ｒの各強磁性板６の渦電流に起因する様々な極性の誘導磁場と到来外乱磁場Ｂｏとが合成される結果、空間Ｒの内側の離れたセンサ位置Ｓと対象位置Ｐとでは内部磁場Ｂｅに位相差δ（位相の分布）が生じる。 In FIG. 8A, if the sensor position S and the target position P are separated from each other, one of the causes for the deterioration of the shield performance is the magnetic field Be at each position inside the shield target space R (hereinafter referred to as the internal magnetic field Be). The phase difference δ occurs. That is, in general, when the magnetic flux density φ of the incoming disturbance magnetic field Bo is changed in the passive magnetic shield, an eddy current of an electromotive force e (= −dφ / dt) is induced in the ferromagnetic plate (conductor) 6 as shown in the illustrated example. In the sealed shield structure 7 in which the entire inner surface of the target space R is covered with the ferromagnetic plate 6, eddy currents having different directions flow through the ferromagnetic plate 6 on each inner surface according to the direction of the incoming disturbance magnetic field Bo, thereby causing the internal magnetic field Be to flow. Attenuate. For example, as shown in FIGS. 6A and 6B, when the magnetic flux density φ of the incoming disturbance magnetic field Bo in the X-axis direction changes, the ferromagnetic plate 6 on the front and rear YZ planes intersecting the X-axis direction of the space R As a result of the increase in current density at the outer periphery and the induction magnetic field generated due to the eddy current and the incoming disturbance magnetic field Bo are synthesized, the internal magnetic field Be on the front and rear YZ planes is in phase with the outer incoming magnetic field Bo. Shifts. Further, the current density also increases in the upper and lower XZ plane ferromagnetic plates 6 parallel to the X axis direction of the space R, and similarly, a phase shift occurs in the internal magnetic field Be of the upper and lower XZ planes. The induced magnetic field generated due to the eddy current is different in polarity from the front and rear YZ planes. In this way, as a result of synthesizing the induction magnetic field of various polarities and the incoming disturbance magnetic field Bo due to the eddy currents of the ferromagnetic plates 6 in the space R, the sensor position S and the target position P that are separated from each other inside the space R. Causes a phase difference δ (phase distribution) in the internal magnetic field Be.
対象位置Ｐとセンサ位置Ｓとで内部磁場Ｂｅに位相差δが生じると、図８（Ｂ）に示すアクティブ型磁気シールドの磁気シールド性能が低下しうる。複合型磁気シールドでは、上述したようにパッシブ型で減衰された内部磁場Ｂｅに対してアクティブ型の補償コイル１２の生成する補償磁場Ｂｃを重畳し、その重畳磁場Ｂｓ（＝Ｂｅ−Ｂｃ）がゼロに近付くようにフィードバック系でコイル電流を調整する。このアクティブ型磁気シールドの磁気シールド性能（相殺性能）ＳＥｓは、重畳磁場Ｂｓに対する内部磁場Ｂｅの比率（＝Ｂｅ／Ｂｓ）として定義され、（１）〜（３）式のように一巡伝達関数Ｇ（ω）を用いて評価することができる。一般にアクティブ型磁気シールドの一巡伝達関数Ｇ（ω）は磁気センサ１４、制御装置１６、補償コイル１２の特性によって定まり、それ自体に位相遅延が生じていることもあるが、（３）式から分かるように伝達関数Ｇ（ω）が大きいほど性能ＳＥｓが高くなる。対象位置Ｐとセンサ位置Ｓとの間に位相差δが生じると、伝達関数Ｇ（ω）の位相遅延が大きくなり、一般的にはそれに応じて伝達関数Ｇ（ω）が小さくなって性能ＳＥｓの低下を招く。図８（Ａ）のように補償コイル１２がパッシブ型（強磁性板６）の内側に配置されているときは、位相差δが更に大きくなると、補償コイル１２の駆動によって対象位置Ｐの内部磁場Ｂｅが逆に大きくなり、アクティブ型磁気シールドが対象位置Ｐの外乱要因となることも起こり得る。
When the phase difference δ occurs in the internal magnetic field Be between the target position P and the sensor position S, the magnetic shield performance of the active magnetic shield shown in FIG. In the composite magnetic shield, the compensation magnetic field Bc generated by the active compensation coil 12 is superimposed on the passive magnetic field Be attenuated as described above, and the superposition magnetic field Bs (= Be−Bc) is zero. The coil current is adjusted by a feedback system so as to approach The magnetic shield performance (cancellation performance) SEs of this active magnetic shield is defined as the ratio of the internal magnetic field Be to the superposed magnetic field Bs (= Be / Bs), and the one-round transfer function G is expressed by the equations (1) to (3). It can be evaluated using (ω). In general, the circular transfer function G (ω) of the active magnetic shield is determined by the characteristics of the magnetic sensor 14, the control device 16, and the compensation coil 12, and there may be a phase delay in itself. Thus, the performance SEs increases as the transfer function G (ω) increases. When the phase difference δ occurs between the target position P and the sensor position S, the phase delay of the transfer function G (ω) increases, and generally the transfer function G (ω) decreases accordingly, and the performance SEs. Cause a decline. When the compensation coil 12 is disposed inside the passive type (ferromagnetic plate 6) as shown in FIG. 8A, when the phase difference δ further increases, the internal magnetic field at the target position P is driven by the compensation coil 12. On the contrary, Be may increase and the active magnetic shield may become a disturbance factor of the target position P.
図９は、一定のシステム構成及び到来外乱磁場の条件を仮定したうえで、アクティブ型磁気シールドの相殺性能（シールド性能）ＳＥｓと内部磁場Ｂｅの位相差δとの関係を計算したグラフの一例を示す。同グラフは、位相差δが１０度未満であれば初期性能の８０％以上の相殺性能を確保できるが、位相差δが２０度以上になると初期性能の７０％以下に相殺性能が低下することを示している。すなわち、シールド対象位置Ｐとセンサ位置Ｓとが離隔しているシールド対象空間Ｒでは、複合型磁気シールドによって高いシールド性能を効率的に確保するために、単にパッシブ型（強磁性板６）とアクティブ型（補償コイル１２）との配置関係等を調整するだけは足りず、両位置Ｐ、Ｓの離隔により生じる性能の劣化（内部磁場Ｂｅの位相差δによる性能劣化）を防止することが重要となる。 FIG. 9 shows an example of a graph in which the relationship between the canceling performance (shielding performance) SEs of the active magnetic shield and the phase difference δ of the internal magnetic field Be is calculated, assuming a certain system configuration and the condition of the incoming disturbance magnetic field. Show. The graph shows that if the phase difference δ is less than 10 degrees, the cancellation performance of 80% or more of the initial performance can be secured, but if the phase difference δ is 20 degrees or more, the cancellation performance decreases to 70% or less of the initial performance. Is shown. That is, in the shield target space R in which the shield target position P and the sensor position S are separated from each other, in order to efficiently ensure high shielding performance by the composite magnetic shield, the passive type (ferromagnetic plate 6) and the active type are simply used. It is not only necessary to adjust the arrangement relationship with the mold (compensation coil 12), and it is important to prevent performance degradation caused by the separation of the positions P and S (performance degradation due to the phase difference δ of the internal magnetic field Be). Become.
そこで本発明の目的は、シールド対象位置とセンサ位置とが離れていてもシールド性能の劣化を防止できる外乱磁場の複合型磁気シールド構築方法を提供することにある。 Therefore, an object of the present invention is to provide a composite magnetic shield construction method for a disturbance magnetic field that can prevent deterioration of shield performance even if the shield target position and the sensor position are separated.
本発明者は、図７に示すような簾状に並べた帯状磁性板の群（以下、シールド簾体という）を用いた磁気シールド構造に着目した（特許文献２及び３参照）。図示例のシールド構造は、図７（Ａ）のように所定幅Ｗ（例えば３０〜１００ｍｍ程度）の複数の帯状磁性板２を長手方向中心軸Ｃが同一簾面Ｆ上にほぼ平行に並ぶように所定間隔ｄで積層してシールド簾体３とし、更に図７（Ｂ）に示すように複数のシールド簾体３ａ、３ｂ、３ｃ、３ｄを対応する帯状磁性板２の端縁の重ね合わせ（面接触、図中の符号９参照）によって磁気的に接合して列状構造としたものである。図７（Ｂ）のように、列状のシールド簾体３の一端側の未接合端縁を他端側の対応する未接合端縁と接合し、磁気的に閉じた環状磁性板４の群を形成することにより、所定間隔ｄで筒型に積層された環状磁性板４の群によりシールド対象空間Ｒを囲むパッシブ型磁気シールド構造５（以下、筒型磁性板群５ということがある）を形成することができる。 The inventor paid attention to a magnetic shield structure using a group of strip-like magnetic plates (hereinafter referred to as a shield case) arranged in a bowl shape as shown in FIG. 7 (see Patent Documents 2 and 3). The shield structure of the illustrated example has a plurality of strip-like magnetic plates 2 having a predetermined width W (for example, about 30 to 100 mm) as shown in FIG. Are laminated at a predetermined interval d to form a shield housing 3, and a plurality of shield housings 3a, 3b, 3c, 3d are overlapped on the corresponding edges of the strip-shaped magnetic plate 2 (see FIG. 7B). It is magnetically joined by surface contact (see reference numeral 9 in the figure) to form a line structure. As shown in FIG. 7B, a group of annular magnetic plates 4 in which the unjoined edge on one end side of the row-shaped shield housing 3 is joined with the corresponding unjoined edge on the other end side and magnetically closed. By forming a passive magnetic shield structure 5 (hereinafter sometimes referred to as a cylindrical magnetic plate group 5) that surrounds the shield target space R by a group of annular magnetic plates 4 laminated in a cylindrical shape at a predetermined interval d. Can be formed.
図７（Ａ）のシールド簾体３は、各磁性板２の相互間隔ｄにより開放性（透視性、透光性、放熱性）を有している。その間隔ｄは、磁性板２中の磁束の通りやすさ（磁性板のパーミアンス）が間隔ｄ中の磁束の通りやすさ（間隔のパーミアンス）より大きくなるように、すなわち簾体３の長手方向中心線Ｃと直交する間隔ｄの断面積Ｓａに対する磁性板２の断面積Ｓｍと比透磁率μとの積（Ｓｍ・μ）の割合（Ｓｍ・μ／Ｓａ）が１より大きくなるように設計する。また図７（Ｂ）の開放性を有する筒型磁性板群５は、磁気的に閉じた環状磁性板４を磁束の通りやすい閉磁路（磁束の漏れにくい磁気回路）として磁束を集中させ、間隔ｄからの磁気の漏洩（シールド性能の劣化）を小さく抑えることにより、同じ量の磁性板料を用いた密閉型シールド構造７（図８（Ａ）参照）と同等以上の性能を有している（特許文献２参照）。 The shield housing 3 in FIG. 7A has openness (transparency, translucency, heat dissipation) due to the mutual distance d between the magnetic plates 2. The interval d is set so that the magnetic flux passing through the magnetic plate 2 (permeance of the magnetic plate) is larger than the magnetic flux passing through the interval d (permeance of the interval), that is, the longitudinal center of the housing 3. The ratio (Sm · μ / Sa) of the product (Sm · μ) of the cross sectional area Sm of the magnetic plate 2 and the relative permeability μ to the cross sectional area Sa of the interval d orthogonal to the line C is designed to be greater than 1. . The cylindrical magnetic plate group 5 having openness shown in FIG. 7B concentrates the magnetic flux by using the magnetically closed annular magnetic plate 4 as a closed magnetic circuit (a magnetic circuit in which magnetic flux is difficult to leak). By suppressing magnetic leakage from d (deterioration of shielding performance) to a small level, it has the same or better performance as the sealed shield structure 7 (see FIG. 8A) using the same amount of magnetic plate material. (See Patent Document 2).
図６（Ｃ）及び図６（Ｄ）は、図７（Ｂ）の筒型磁性板群５の中心軸線（筒軸）をシールド対象空間ＲのＺ軸に芯合わせして配置し、Ｘ軸方向の到来外乱磁場Ｂｏの磁束密度φの変化によって筒型磁性板群５の各環状磁性板４に誘導される渦電流を示したものである。筒型磁性板群５では、図６（Ａ）及び（Ｂ）の密閉型シールド構造７の場合と同様に渦電流が誘導されるものの、環状磁性板４の相互間隔ｄによって電流経路が分断されているため、密閉型シールド構造７の前後ＹＺ面のような大きな鎖交面積をもった渦電流は生じない。また、環状磁性板４の各部分が到来外乱磁場Ｂｏと平行になっており、各部分に流れる渦電流の極性向きが揃っているので、渦電流に起因する誘導磁場によってシールド構造の内部磁場Ｂｅに大きな位相差δ（位相の分布）が生じにくいと予想される。 6 (C) and 6 (D) are arranged so that the central axis (cylinder axis) of the cylindrical magnetic plate group 5 of FIG. 7 (B) is aligned with the Z axis of the shielded space R, and the X axis The eddy current induced to each annular magnetic plate 4 of the cylindrical magnetic plate group 5 by the change of the magnetic flux density φ of the incoming disturbance magnetic field Bo in the direction is shown. In the cylindrical magnetic plate group 5, eddy currents are induced as in the case of the sealed shield structure 7 of FIGS. 6A and 6B, but the current path is divided by the mutual distance d of the annular magnetic plates 4. Therefore, an eddy current having a large interlinkage area such as the front and rear YZ planes of the sealed shield structure 7 does not occur. In addition, since each part of the annular magnetic plate 4 is parallel to the incoming disturbance magnetic field Bo and the polar direction of the eddy current flowing through each part is uniform, the internal magnetic field Be of the shield structure is induced by the induced magnetic field caused by the eddy current. It is expected that a large phase difference δ (phase distribution) hardly occurs.
本発明者は、図４に示すように、複数の径Ｄの環状磁性板４（図示例ではロ字型の磁性板）を所定筒軸（図示例ではＺ軸）に芯合わせして所定間隔ｄで筒型に積層することにより全長Ｌ（＝Ｄ×２）の磁気シールド構造（筒型磁性板群）５を試作し、到来外乱磁場Ｂｏによって生じるシールド構造の内部磁場Ｂｅの位相分布を確認する実験を行った。本実験では、図４（Ｂ）に示すように、筒型磁性板群５の両端から等距離（＝Ｌ／２）のＺ軸上に原点Ｐを設けると共に、その原点Ｐを通る環状磁性板４と平行な平面上のＹ軸及びＸ軸上に計測点Ｓ１、Ｓ２（原点Ｐからの距離＝環状磁性板４の径Ｄの１／３）を設け、Ｘ軸方向からの到来外乱磁場Ｂｏの周波数を変えながら、その到来外乱磁場Ｂｏの変動に対する原点Ｐ及び計測点Ｓ１、Ｓ２の各々の内部磁場Ｂｅの位相のずれ（位相の変位）を計測した。また、図４（Ｃ）に示すように、原点Ｐから隔てた軸線Ｚ上に計測点Ｓ３（原点Ｐからの距離＝筒型磁性板群５の長さＬの１／６）を設け、同様にしてＸ軸方向の到来外乱磁場Ｂｏの変動に対する計測点Ｓ３の内部磁場Ｂｅの位相変位を計測した。 As shown in FIG. 4, the present inventor aligns a plurality of annular magnetic plates 4 having a diameter D (in the illustrated example, a letter-shaped magnetic plate) with a predetermined cylinder axis (in the illustrated example, the Z axis) at predetermined intervals. The magnetic shield structure (cylindrical magnetic plate group) 5 having a total length L (= D × 2) is fabricated by stacking in a cylindrical shape with d, and the phase distribution of the internal magnetic field Be of the shield structure generated by the incoming disturbance magnetic field Bo is confirmed. An experiment was conducted. In this experiment, as shown in FIG. 4B, an origin P is provided on the Z axis equidistant (= L / 2) from both ends of the cylindrical magnetic plate group 5, and an annular magnetic plate passing through the origin P is provided. Measurement points S1 and S2 (distance from the origin P = 1/3 of the diameter D of the annular magnetic plate 4) are provided on the Y axis and the X axis on a plane parallel to 4, and the incoming disturbance magnetic field Bo from the X axis direction is provided. The phase shift (phase displacement) of the internal magnetic field Be at each of the origin P and the measurement points S1 and S2 with respect to the fluctuation of the incoming disturbance magnetic field Bo was measured. Further, as shown in FIG. 4C, a measurement point S3 (distance from the origin P = 1/6 of the length L of the cylindrical magnetic plate group 5) is provided on the axis Z separated from the origin P. Thus, the phase displacement of the internal magnetic field Be at the measurement point S3 with respect to the fluctuation of the incoming disturbance magnetic field Bo in the X-axis direction was measured.
図５のグラフは、図４の実験結果、すなわち原点Ｐ及び各計測点Ｓ１、Ｓ２、Ｓ３における内部磁場Ｂｅの到来外乱磁場Ｂｏに対する位相変位の計測結果を示す。同グラフから、到来外乱磁場Ｂｏの周波数が１〜２００Ｈｚの間で変化しても、筒型磁性板群５の内部の原点Ｐ及び計測点Ｓ１、Ｓ２では位相差δが１．５度以内に収まっており、筒軸（Ｚ軸）と垂直な環状磁性板４と平行な平面上では位相差δがほとんど生じていないことが分かる。また、筒軸（Ｚ軸）方向に隔てた原点Ｐと計測点Ｓ３との間でも位相差δは９．２度以内に収まっており、筒軸（Ｚ軸）方向に生じる位相の分布も緩やかなものであることが分かる。図９を参照して上述したように、位相差δが１０度以下であればアクティブ型磁気シールドの相殺性能（シールド性能）ＳＥｓが大幅に低下することはなく、初期性能の８０％以上のシールド性能を確保できる。すなわち、図８のように密閉型シールド構造７に代えて、図７のような筒型磁性板群５（開放型シールド構造５）を用いて複合型磁気シールドを構築すれば、シールド対象位置Ｐとセンサ位置Ｓとが離れていても、両位置Ｐ、Ｓの位相差δに起因する性能の劣化を防止することが期待できる。本発明は、この着想に基づく研究開発によって完成に至ったものである。 The graph of FIG. 5 shows the experimental result of FIG. 4, that is, the measurement result of the phase displacement of the internal magnetic field Be at the origin P and the measurement points S1, S2, and S3 with respect to the incoming disturbance magnetic field Bo. From the graph, even if the frequency of the incoming disturbance magnetic field Bo changes between 1 and 200 Hz, the phase difference δ is within 1.5 degrees at the origin P and the measurement points S1 and S2 inside the cylindrical magnetic plate group 5. It can be seen that there is almost no phase difference δ on a plane parallel to the annular magnetic plate 4 perpendicular to the cylinder axis (Z axis). Also, the phase difference δ is within 9.2 degrees between the origin P and the measurement point S3 separated in the cylinder axis (Z-axis) direction, and the phase distribution generated in the cylinder axis (Z-axis) direction is also gradual. You can see that As described above with reference to FIG. 9, if the phase difference δ is 10 degrees or less, the cancellation performance (shield performance) SEs of the active magnetic shield is not significantly lowered, and the shield has 80% or more of the initial performance. Performance can be secured. That is, instead of the sealed shield structure 7 as shown in FIG. 8, if a composite magnetic shield is constructed using the cylindrical magnetic plate group 5 (open shield structure 5) as shown in FIG. Even if the sensor position S is far from the sensor position S, it can be expected to prevent deterioration in performance due to the phase difference δ between the positions P and S. The present invention has been completed through research and development based on this idea.
図１の実施例を参照するに、本発明による外乱磁場の複合型磁気シールド構築方法は、シールド対象空間Ｒ内の所定対象位置Ｐ上に到来外乱磁場Ｂｏの方向と垂直な軸線Ｍを想定し且つその軸線Ｍと交差する所定間隔ｄの平行な複数の平面Ｑ上に空間Ｒの外縁に沿って環状磁性板４の群５（図７（Ｂ）参照）を筒型に配置し、筒型磁性板群５の内側又は外側の対象位置Ｐの周囲に補償磁場発生用コイル１２ａ、１２ｂを設置し、対象位置Ｐに対して位相差δが１０度以下の内部磁場Ｂｅを検出できる筒型磁性板群５内の離隔位置Ｓを選定して磁気センサ１４を設け、センサ１４の出力に応じてコイル１２ａ、１２ｂの補償磁場を制御して対象位置Ｐの内部磁場Ｂｅを減衰させてなるものである。 Referring to the embodiment of FIG. 1, the disturbance magnetic field composite magnetic shield construction method according to the present invention assumes an axis M perpendicular to the direction of the incoming disturbance magnetic field Bo on a predetermined target position P in the shield target space R. A group 5 (see FIG. 7B) of the annular magnetic plate 4 is arranged in a cylindrical shape along the outer edge of the space R on a plurality of parallel planes Q intersecting the axis M at a predetermined interval d. Compensation magnetic field generating coils 12a and 12b are installed around a target position P inside or outside the magnetic plate group 5, and a cylindrical magnet capable of detecting an internal magnetic field Be having a phase difference δ of 10 degrees or less with respect to the target position P. The magnetic sensor 14 is provided by selecting the separation position S in the plate group 5, and the compensation magnetic field of the coils 12a and 12b is controlled according to the output of the sensor 14 to attenuate the internal magnetic field Be at the target position P. is there.
好ましくは、磁気センサ１４を、対象位置Ｐを通る環状磁性板４と平行な平面Ｑ上に設ける。或いは、対象位置Ｐに対して位相差δが１０度以下の内部磁場Ｂｅを検出できる筒型磁性板群５内の軸線Ｍ方向の離隔許容範囲を検出し、磁気センサ１４を、対象位置Ｐから離隔許容範囲内の環状磁性４板と平行な平面Ｑ上に設けてもよい。 Preferably, the magnetic sensor 14 is provided on a plane Q parallel to the annular magnetic plate 4 passing through the target position P. Alternatively, the separation allowable range in the axis M direction in the cylindrical magnetic plate group 5 that can detect the internal magnetic field Be having a phase difference δ of 10 degrees or less with respect to the target position P is detected, and the magnetic sensor 14 is moved from the target position P. You may provide on the plane Q parallel to the cyclic | annular magnetic 4 plate in a space | interval tolerance.
更に好ましくは、対象位置Ｐを筒型磁性板群５の軸線Ｍ方向の中心とし、筒型磁性板群５の軸線Ｍ方向の長さＬを環状磁性板４の径Ｄの２倍以上とする。必要に応じて、図２に示すように、軸線Ｍと交差する筒型磁性板群５の両端面に磁気シールド面８を配置してもよい。 More preferably, the target position P is the center of the cylindrical magnetic plate group 5 in the axis M direction, and the length L of the cylindrical magnetic plate group 5 in the axis M direction is at least twice the diameter D of the annular magnetic plate 4. . If necessary, as shown in FIG. 2, magnetic shield surfaces 8 may be arranged on both end surfaces of the cylindrical magnetic plate group 5 intersecting the axis M.
本発明による外乱磁場の複合型磁気シールド構築方法は、シールド対象空間Ｒ内の所定対象位置Ｐ上に到来外乱磁場Ｂｏの到来方向と垂直な軸線Ｍを想定し、その軸線Ｍと交差する所定間隔ｄの平行な複数の平面Ｑ上に空間Ｒの外縁に沿って筒型に配置した環状磁性板４の群５によりパッシブ型磁気シールド（図７（Ｂ）参照）を構成し、その筒型磁性板群５の内側又は外側の対象位置Ｐの周囲に設置した補償磁場発生用コイル１２ａ、１２ｂと、対象位置Ｐに対して位相差δが１０度以下の内部磁場Ｂｅを検出できる筒型磁性板群５内の離隔位置Ｓを選定して設けた磁気センサ１４とによりアクティブ型磁気シールド（図８（Ａ）参照）を構成するので、次の効果を奏する。 The composite magnetic shield construction method for disturbance magnetic field according to the present invention assumes an axis M perpendicular to the arrival direction of the incoming disturbance magnetic field Bo on a predetermined target position P in the shield target space R, and a predetermined interval intersecting the axis M. A passive magnetic shield (see FIG. 7 (B)) is formed by a group 5 of annular magnetic plates 4 arranged in a cylindrical shape along the outer edge of the space R on a plurality of parallel planes Q of d, and the cylindrical magnetic Compensation magnetic field generating coils 12a and 12b installed around the target position P inside or outside the plate group 5, and a cylindrical magnetic plate capable of detecting an internal magnetic field Be having a phase difference δ of 10 degrees or less with respect to the target position P Since the active magnetic shield (see FIG. 8A) is configured by the magnetic sensor 14 provided by selecting the separation position S in the group 5, the following effects are obtained.
（イ）筒型磁性板群５をパッシブ型磁気シールドとして用いることにより、シールド対象空間Ｒ内の軸線Ｍと垂直な平面上で内部磁場Ｂｅの位相差δを小さく抑えて位相分布をほぼ一様化することができ、軸線Ｍ方向の内部磁場Ｂｅの位相分布も緩やかなものとすることができる。
（ロ）従来のパッシブ型磁気シールドに比して対象空間Ｒ内の対象位置Ｐ周辺に位相差δの小さい比較的広い領域を形成することができ、位相差δによる性能劣化を避けながらアクティブ磁気シールドのセンサ位置Ｓと対象位置Ｐとの離隔距離を大きくとることが可能になる。
（ハ）従って、アクティブ磁気シールドの対象位置Ｐ周辺の磁気センサ１４の位置選択の自由度を高めることができ、対象空問Ｒ内部に対象位置Ｐの嫌磁気装置（例えばＭＲＩ装置等）と物理的干渉を起こさないようにアクティブ型磁気シールドを適用することが容易になる。
（ニ）また、シールド対象空間Ｒ内の磁場位相差δの急激な変化を生じにくいので、事前に現場で磁気センサ１４の設置位置を探索・選定する作業を行う必要がなくなり、アクティブ型磁気シールドの施工作業の簡単化を図ることができる。
（ホ）到来外乱磁場Ｂｏの強さの分布に対しても筒型磁性板群５の磁性板相互間隔ｄの調整や補償コイル１２の配置位置の調整により比較的容易に対応可能であり、筒型磁性板群５の両端面に磁気シールド面８を配置することで到来外乱磁場Ｂｏの両端部からの回り込みにも対応できる。
(A) By using the cylindrical magnetic plate group 5 as a passive magnetic shield, the phase difference δ of the internal magnetic field Be is kept small on the plane perpendicular to the axis M in the shielded space R, and the phase distribution is substantially uniform. The phase distribution of the internal magnetic field Be in the direction of the axis M can be made gentle.
(B) A relatively wide region having a small phase difference δ can be formed around the target position P in the target space R as compared with a conventional passive magnetic shield, and active magnetism is avoided while avoiding performance deterioration due to the phase difference δ. It is possible to increase the separation distance between the sensor position S of the shield and the target position P.
(C) Accordingly, the degree of freedom in selecting the position of the magnetic sensor 14 around the target position P of the active magnetic shield can be increased, and the anaerobic device (for example, an MRI apparatus or the like) at the target position P is physically located inside the target question R. It becomes easy to apply an active magnetic shield so as not to cause mechanical interference.
(D) In addition, since the magnetic field phase difference δ in the shield target space R is unlikely to change rapidly, there is no need to search and select the installation position of the magnetic sensor 14 in advance on the site, and the active magnetic shield The construction work can be simplified.
(E) The distribution of the intensity of the incoming disturbance magnetic field Bo can be relatively easily handled by adjusting the magnetic plate mutual distance d of the cylindrical magnetic plate group 5 and adjusting the arrangement position of the compensation coil 12. By arranging the magnetic shield surfaces 8 on both end faces of the mold magnetic plate group 5, it is possible to cope with wraparound from both ends of the incoming disturbance magnetic field Bo.
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、本発明の複合型磁気シールド構造の一実施例を示す。図示例の複合型構造は、図７（Ｂ）のように複数の環状磁性板４を所定間隔ｄで積層した筒型磁性板群５を用いた開放型のパッシブ型磁気シールドと、図８（Ａ）と同様のアクティブ型磁気シールドとを組み合わせものである。図示例の筒型磁性板群５は、例えばシールド対象空間Ｒ内に嫌磁気装置（例えばＭＲＩ装置等）を設置すべきシールド対象位置Ｐを定め、その対象位置Ｐ上の軸線Ｍと交差する所定間隔ｄの平行な複数の平面Ｑ上に空間Ｒの外縁に沿って環状磁性板４の群を配置したものである。環状磁性板４の一例は、図５（Ｂ）に示すように短冊形の帯状磁性板２を端縁の重ね合わせにより磁気的に連続させて環状に結合した磁性体フレームである。ただし、環状磁性板４の形状は図示例のような四角形（ロ字形）に限らず、三角形又は多角形とすることができ、楕円形等の曲線で囲まれた環状磁性板４とすることも可能である。軸線Ｍの周りに筒型磁性板群５を配置することにより、対象空間Ｓの４面を囲う閉磁路が形成できる。 FIG. 1 shows an embodiment of a composite magnetic shield structure of the present invention. The composite structure of the illustrated example includes an open type passive magnetic shield using a cylindrical magnetic plate group 5 in which a plurality of annular magnetic plates 4 are laminated at a predetermined interval d as shown in FIG. The active magnetic shield similar to A) is combined. The cylindrical magnetic plate group 5 in the illustrated example defines a shield target position P where a magnetoless device (for example, an MRI apparatus or the like) is to be installed in the shield target space R, and is a predetermined crossing with the axis M on the target position P. A group of annular magnetic plates 4 is arranged along the outer edge of the space R on a plurality of parallel planes Q with a distance d. An example of the annular magnetic plate 4 is a magnetic frame in which strip-shaped magnetic strips 2 are magnetically continuous by overlapping edges as shown in FIG. 5B. However, the shape of the annular magnetic plate 4 is not limited to a quadrangle (b-shaped) as in the illustrated example, but may be a triangle or a polygon, and may be an annular magnetic plate 4 surrounded by a curve such as an ellipse. Is possible. By disposing the cylindrical magnetic plate group 5 around the axis M, a closed magnetic path surrounding the four surfaces of the target space S can be formed.
図示例において、筒型磁性板群５の各環状磁性板４の比透磁率μ、幅Ｗ、相互間隔ｄ等は、例えば筒型磁性板群５の施工前に予めシールド対象空間Ｒの外乱到来磁場Ｂｏの変動を求め、その到来外乱磁場Ｂｏの定常値又は最小値において対象空間Ｒ内の対象位置Ｐで要求される磁場強度（例えば対象位置Ｐに設置する嫌磁気装置の許容磁場強度）が得られるように設計することができる。筒型磁性板群５のシールド性能は、上述したように環状磁性板４の間隔ｄ（断面積Ｓａ）に対する環状磁性板４の幅Ｗ（断面積Ｓｍ）の比率（Ｓｍ・μ／Ｓａ）によって調整可能であるが、例えば幅Ｗに対する間隔ｄの比率を６未満（ｄ／Ｗ＜６）として十分な磁気シールド性能を確保することが望ましい。 In the illustrated example, the relative permeability μ, the width W, the mutual interval d, etc. of each annular magnetic plate 4 of the cylindrical magnetic plate group 5 are, for example, pre-disturbance in the shield target space R before the cylindrical magnetic plate group 5 is constructed. The fluctuation of the magnetic field Bo is obtained, and the magnetic field strength required at the target position P in the target space R at the steady or minimum value of the incoming disturbance magnetic field Bo (for example, the allowable magnetic field strength of the anaerobic device installed at the target position P). Can be designed to be obtained. As described above, the shielding performance of the cylindrical magnetic plate group 5 depends on the ratio (Sm · μ / Sa) of the width W (cross-sectional area Sm) of the annular magnetic plate 4 to the interval d (cross-sectional area Sa) of the annular magnetic plate 4. Although adjustment is possible, it is desirable to ensure sufficient magnetic shielding performance by setting the ratio of the distance d to the width W to be less than 6 (d / W <6), for example.
また筒型磁性板群５は、到来外乱磁場Ｂｏに対して各環状磁性板４中の磁束密度が磁気飽和しないように、環状磁性板４の比透磁率μ、幅Ｗと聞隔ｄとの比率（ｄ／Ｗ）を設計することが望ましい。環状磁性板４は、例えば薄い磁性板（パーマロイ、電磁鋼板等）を複数枚重ねたものとすることができ、その重ね枚数によって環状磁性板４の厚さ及び比透磁率μを調整することができる。筒型磁性板群５の全ての環状磁性板４の比透磁率μ、幅Ｗ、相互間隔ｄ等の属性を揃えることで施工の容易化を図れるが、各環状磁性板４の属性は同じである必要はなく、例えば到来外乱磁場Ｂｏの強さの分布に応じて環状磁性板４毎に属性を相違させることも可能である。例えば、到来外乱磁場Ｂｏの強い部位では比透磁率μや幅Ｗを大きくするか又は間隔ｄを小さくし、到来外乱磁場Ｂｏの弱い部位では比透磁率μや幅Ｗを小さくするか又は間隔ｄを大きくすることができる。 In addition, the cylindrical magnetic plate group 5 includes the relative magnetic permeability μ, the width W, and the interval d of the annular magnetic plate 4 so that the magnetic flux density in each annular magnetic plate 4 is not magnetically saturated with respect to the incoming disturbance magnetic field Bo. It is desirable to design the ratio (d / W). The annular magnetic plate 4 can be formed by stacking a plurality of thin magnetic plates (permalloy, electromagnetic steel plates, etc.), for example, and the thickness and relative permeability μ of the annular magnetic plate 4 can be adjusted by the number of the stacked sheets. it can. Construction can be facilitated by aligning the relative permeability μ, width W, mutual spacing d, etc. of all the annular magnetic plates 4 of the cylindrical magnetic plate group 5, but the attributes of each annular magnetic plate 4 are the same. There is no need, and for example, the attributes can be made different for each annular magnetic plate 4 according to the intensity distribution of the incoming disturbance magnetic field Bo. For example, the relative permeability μ and the width W are increased or the distance d is decreased at a portion where the incoming disturbance magnetic field Bo is strong, and the relative permeability μ and the width W are decreased or the interval d at a portion where the incoming disturbance magnetic field Bo is weak. Can be increased.
筒型磁性板群５は、予めシールド対象空間Ｒの外乱磁場Ｂｏの到来方向を求め、その到来外乱磁場Ｂｏの方向と垂直な対象位置Ｐ上の軸線（筒軸）Ｍと交差するように各環状磁性板４（平面Ｑ）を配置する。筒型磁性板群５の筒軸Ｍを到来外乱磁場Ｂｏの方向と平行に設置すると、図６（Ａ）の場合と同様に環状磁性板４の正面の環状方向に沿って大きな経路の渦電流が誘導され、環状磁性板４上の向きの異なる渦電流の誘導磁場により筒型磁性板群５の内部磁場Ｂｅの位相のずれ（位相の分布）が大きくなる。図示例のように筒型磁性板群５の筒軸Ｍを到来外乱磁場Ｂｏの方向に対して直交させ、各環状磁性板４の側面（厚さ方向断面）を到来外乱磁場Ｂｏと交差させることにより、環状磁性板４上に環状方向に沿った大きな経路の渦電流が誘導されることを抑制し、対象空間Ｒの内部磁場Ｂｅの位相のずれ（位相の分布）を小さく抑えることができる。 The cylindrical magnetic plate group 5 obtains the arrival direction of the disturbance magnetic field Bo in the shield target space R in advance, and crosses the axis (cylinder axis) M on the target position P perpendicular to the direction of the arrival disturbance magnetic field Bo. An annular magnetic plate 4 (plane Q) is disposed. When the cylindrical axis M of the cylindrical magnetic plate group 5 is installed in parallel with the direction of the incoming disturbance magnetic field Bo, an eddy current of a large path along the annular direction of the front surface of the annular magnetic plate 4 as in the case of FIG. The phase shift (phase distribution) of the internal magnetic field Be of the cylindrical magnetic plate group 5 is increased by the induced magnetic field of the eddy currents with different directions on the annular magnetic plate 4. As shown in the example, the cylindrical axis M of the cylindrical magnetic plate group 5 is orthogonal to the direction of the incoming disturbance magnetic field Bo, and the side surface (thickness direction cross section) of each annular magnetic plate 4 intersects the incoming disturbance magnetic field Bo. Thus, it is possible to suppress induction of eddy currents in a large path along the annular direction on the annular magnetic plate 4 and to suppress a phase shift (phase distribution) of the internal magnetic field Be in the target space R.
好ましくは、図示例のように筒型磁性板群５の筒軸Ｍと各環状磁性板４（平面Ｑ）とを直角に交差させ、環状磁性板４の環状方向に沿って誘導される渦電流を最小限に抑える。ただし、筒軸Ｍと各環状磁性板４とは厳密に直交させる必要はなく、環状磁性板４上に環状方向の渦電流が誘導されるのを防止できる角度で交差させれば足りる。また、各環状磁性板４の筒軸Ｍとの交差角度は全て同じである必要はなく、例えば到来外乱磁場Ｂｏの強さの分布に応じて環状磁性板４毎に交差角度を変えることも可能である。 Preferably, as shown in the drawing, the cylindrical axis M of the cylindrical magnetic plate group 5 and each annular magnetic plate 4 (plane Q) intersect at right angles, and eddy currents are induced along the annular direction of the annular magnetic plate 4. To minimize. However, the cylinder axis M and each annular magnetic plate 4 do not have to be strictly orthogonal, and it is sufficient if they intersect at an angle that can prevent induction of an eddy current in the annular direction on the annular magnetic plate 4. Further, the crossing angles of the annular magnetic plates 4 with the cylinder axis M need not all be the same. For example, the crossing angles can be changed for each of the annular magnetic plates 4 in accordance with the intensity distribution of the incoming disturbance magnetic field Bo. It is.
なお、図示例ではＸ軸、Ｙ軸、又はＺ軸と垂直な壁面に囲まれた立方体形状のシールド対象空間Ｒ（磁気シールドルーム等）を想定し、その壁面と垂直な方向（Ｚ軸方向）からの到来外乱磁場Ｂｏを対象としているが、本発明の対象とする到来外乱磁場Ｂｏは対象空間Ｒの壁面と垂直方向に到来する磁場に限定されるものではない。例えば図３の実施例に示すように、到来外乱磁場Ｂｏの方向に拘らず、その到来外乱磁場Ｂｏと垂直な軸線（筒軸）Ｍと交差するように複数の環状磁性板４を適当な間隔ｄで配置すれば、その環状磁性板４（筒型磁性板群５）で囲まれた対象空間Ｒの内部磁場Ｂｅの位相のずれ（位相の分布）を小さく抑えることができる。図３の実施例では対象空間Ｒの端面と筒型磁性板群５の端面とが揃わなくなり、筒型磁性板群５の端面から到来外乱磁場Ｂｏが対象空間Ｒの内側に進入するおそれも生じるが、そのような端面の影響は後述するように筒型磁性板群５の端面に磁気シールド面８を配置することで対応可能である（図２参照）。 In the illustrated example, a cube-shaped shield target space R (such as a magnetic shield room) surrounded by a wall surface perpendicular to the X-axis, Y-axis, or Z-axis is assumed, and a direction perpendicular to the wall surface (Z-axis direction). However, the incoming disturbance magnetic field Bo that is the subject of the present invention is not limited to the magnetic field that arrives in the direction perpendicular to the wall surface of the target space R. For example, as shown in the embodiment of FIG. 3, regardless of the direction of the incoming disturbance magnetic field Bo, a plurality of annular magnetic plates 4 are arranged at appropriate intervals so as to intersect the axis (cylinder axis) M perpendicular to the incoming disturbance magnetic field Bo. If it arrange | positions by d, the shift | offset | difference (phase distribution) of the internal magnetic field Be of the object space R enclosed by the annular magnetic plate 4 (tubular magnetic plate group 5) can be suppressed small. In the embodiment of FIG. 3, the end face of the target space R and the end face of the cylindrical magnetic plate group 5 are not aligned, and the incoming disturbance magnetic field Bo may enter the inside of the target space R from the end face of the cylindrical magnetic plate group 5. However, the influence of such an end face can be dealt with by arranging the magnetic shield surface 8 on the end face of the cylindrical magnetic plate group 5 as described later (see FIG. 2).
また、図１及び図３の実施例では、筒軸Ｍと交差する平面Ｑと対象空間Ｒの外縁との交線に沿って環状磁性板４を配置し、環状磁性板４の径Ｄと対象空間Ｒ（磁気シールドルーム等）の断面径とを一致させているが、環状磁性板４の径Ｄと対象空間Ｒの断面径とは必ずしも一致させなくてもよく、例えば環状磁性板４の径Ｄを対象空間Ｒの断面径より小径としてもよい。また、対象空間Ｒの外側に筒型磁性板群５を配置することが可能であれば、環状磁性板４の径Ｄを対象空間Ｒの断面径より大径とし、対象空間Ｒの外側の筒型磁性板群５によって対象空間Ｒの内部磁場Ｂｅの位相のずれ（位相の分布）を小さく抑えることも可能である。 1 and 3, the annular magnetic plate 4 is disposed along the intersection line between the plane Q intersecting the cylinder axis M and the outer edge of the target space R, and the diameter D of the annular magnetic plate 4 and the target The cross-sectional diameter of the space R (magnetic shield room or the like) is made to coincide, but the diameter D of the annular magnetic plate 4 and the cross-sectional diameter of the target space R do not necessarily coincide. For example, the diameter of the annular magnetic plate 4 D may be smaller than the cross-sectional diameter of the target space R. Further, if the cylindrical magnetic plate group 5 can be arranged outside the target space R, the diameter D of the annular magnetic plate 4 is made larger than the cross-sectional diameter of the target space R, and the cylinder outside the target space R is set. It is also possible to suppress a phase shift (phase distribution) of the internal magnetic field Be in the target space R by the mold magnetic plate group 5.
図示例のアクティブ型磁気シールドは、筒型磁性板群５の内側又は外側の対象位置Ｐの周囲に設置した一対の補償コイル１２ａ、１２ｂと、筒型磁性板群５内の対象位置Ｐから離隔したセンサ位置Ｓに設けた磁気センサ１４と、磁気センサ１４の計測磁場（内部磁場）Ｂｅを入力して補償コイル１２ａ、１２ｂの補償磁場を制御する制御装置１６とを有する。図示例の補償コイル１２ａ、１２ｂは、それぞれ対象空間Ｒの対象位置Ｐを通るＸ軸に芯合わせして筒型磁性板群５の内側に設置されており、図８（Ａ）の場合と同様に比較的小さな電流でＸ軸方向の外乱磁場を減衰させ、対象位置Ｐ付近に比較的広い補償磁場を形成することができる。ただし、補償コイル１２の配置位置及び形状は図示例に限定されず、必要な場合は筒型磁性板群５の外側に配置してもよい。また、対象空間Ｒの内面（図示例のＹＺ面）を複数に分割して各領域に補償コイル１２を配置し、各領域の補償コイル１２によって対象位置Ｐ付近に補償磁場を形成してもよい。 The active type magnetic shield of the illustrated example is separated from the target position P in the cylindrical magnetic plate group 5 and the pair of compensation coils 12 a and 12 b installed around the target position P inside or outside the cylindrical magnetic plate group 5. The magnetic sensor 14 provided at the sensor position S and the control device 16 that inputs the measurement magnetic field (internal magnetic field) Be of the magnetic sensor 14 and controls the compensation magnetic field of the compensation coils 12a and 12b. The compensation coils 12a and 12b in the illustrated example are each positioned inside the cylindrical magnetic plate group 5 so as to be aligned with the X axis passing through the target position P in the target space R, and are the same as in the case of FIG. The disturbance magnetic field in the X-axis direction can be attenuated with a relatively small current, and a relatively wide compensation magnetic field can be formed in the vicinity of the target position P. However, the arrangement position and shape of the compensation coil 12 are not limited to the illustrated example, and may be arranged outside the cylindrical magnetic plate group 5 if necessary. Further, the inner surface (YZ plane in the illustrated example) of the target space R may be divided into a plurality of areas, and the compensation coil 12 may be arranged in each region, and a compensation magnetic field may be formed near the target position P by the compensation coil 12 in each region. .
図示例のように到来外乱磁場Ｂｏの方向に対して筒軸Ｍが垂直な筒型磁性板群５を設置すれば、図５を参照して上述したように、対象位置Ｐを通る環状磁性板４と平行な平面Ｑ（ＸＹ平面）上で筒型磁性板群５の内部磁場Ｂｅの位相のずれ（位相分布）をほぼ一様化することができる。従って、その平面Ｑ上であれば、対象位置Ｐから離れた位置Ｓ（例えば対象位置Ｐの直上の天井に近い位置）に磁場センサ１４を設けても、内部磁場Ｂｅの位相差δによるアクティブ磁気シールドの性能劣化を避けることができる。また、対象位置Ｐを通る平面Ｑ上であればセンサ位置Ｓを任意に選択することが可能であり、センサ位置Ｓの選択の自由度を高めると共に、現場で事前にセンサ位置Ｓを探索・選定する作業を省略して施工作業の簡単化を図ることができる。 If the cylindrical magnetic plate group 5 having the cylinder axis M perpendicular to the direction of the incoming disturbance magnetic field Bo is installed as in the illustrated example, the annular magnetic plate passing through the target position P as described above with reference to FIG. 4, the phase shift (phase distribution) of the internal magnetic field Be of the cylindrical magnetic plate group 5 on the plane Q (XY plane) parallel to 4 can be made substantially uniform. Therefore, even if the magnetic field sensor 14 is provided at a position S away from the target position P (for example, a position close to the ceiling directly above the target position P) on the plane Q, the active magnetism due to the phase difference δ of the internal magnetic field Be. The performance degradation of the shield can be avoided. Further, the sensor position S can be arbitrarily selected as long as it is on the plane Q passing through the target position P, and the degree of freedom of selection of the sensor position S is increased, and the sensor position S is searched and selected in advance at the site. It is possible to simplify the construction work by omitting the work to be performed.
好ましくは、筒型磁性板群５の軸線Ｍ方向の長さＬを環状磁性板４の径Ｄの２倍以上とし、対象位置Ｐを筒型磁性板群５の軸線方向の中心付近に設ける。筒型磁性板群５の筒軸Ｍ方向の長さＬが環状磁性板４の径Ｄに比して同程度又は短いと、筒型磁性板群５の両端面から到来外乱磁場Ｂｏが対象空間Ｒの内側に回り込み、端部の影響によって内部磁場Ｂｅの位相分布が影響を受けるおそれがある。本発明者は、筒型磁性板群５の軸線方向中心でほぼ一様な位相分布が得られる軸線方向長さＬを検討する実験を繰り返し、筒型磁性板群５の軸線方向長さＬを環状磁性板４の径Ｄの２倍以上の比率（Ｌ／Ｄ＞２）とすれば、筒型磁性板群５の軸線方向中心で端面の影響が避けられることを見出した。ただし、例えば大きさの限られた対象空間Ｒ（磁気シールドルーム等）のように比率（Ｌ／Ｄ）を大きくすることが難しい場合でも、後述するように筒型磁性板群５の両端面に磁気シールド面８を配置する等の別の手段によって端部の影響を小さく抑えることができ、本発明を適用することができる。 Preferably, the length L in the axis M direction of the cylindrical magnetic plate group 5 is at least twice the diameter D of the annular magnetic plate 4, and the target position P is provided near the center of the cylindrical magnetic plate group 5 in the axial direction. When the length L in the cylinder axis M direction of the cylindrical magnetic plate group 5 is approximately equal to or shorter than the diameter D of the annular magnetic plate 4, the incoming disturbance magnetic field Bo is detected from both end faces of the cylindrical magnetic plate group 5 in the target space. There is a possibility that the phase distribution of the internal magnetic field Be may be affected by the influence of the end portion that goes around inside R. The inventor repeated an experiment to examine the axial length L at which the substantially uniform phase distribution is obtained at the axial center of the cylindrical magnetic plate group 5, and the axial length L of the cylindrical magnetic plate group 5 was determined. It has been found that if the ratio of the diameter D of the annular magnetic plate 4 is at least twice (L / D> 2), the influence of the end face can be avoided at the center of the cylindrical magnetic plate group 5 in the axial direction. However, even if it is difficult to increase the ratio (L / D), for example, in a limited space R (magnetic shield room or the like), for example, on both end faces of the cylindrical magnetic plate group 5 as described later. The influence of the end portion can be reduced by another means such as disposing the magnetic shield surface 8, and the present invention can be applied.
また、筒型磁性板群５の軸線Ｍ方向の長さＬを環状磁性板４の径Ｄの２倍以上とすれば、図４（Ｂ）に示したように、筒型磁性板群５の中心付近の軸線方向の位相分布を緩やかなものとすることができる。従って、対象位置Ｐに対して位相差δが許容範囲内（例えば１０度以下）の内部磁場Ｂｅを検出できる筒型磁性板群５内の軸線Ｍ方向の離隔許容範囲（例えば図４（Ｂ）に示す軸線方向長さＬの１／６）を検出し、対象位置Ｐからその離隔許容（Ｌ／６）の範囲内の環状磁性４板と平行な平面Ｑ上に磁場センサ１４を設けても、内部磁場Ｂｅの位相差δによるアクティブ磁気シールドの大きな性能劣化を避けることができる。そのような軸線Ｍ方向の離隔許容範囲は、現場で事前に探索・選定することも可能であるが、図４（Ｂ）のような筒型磁性板群５の模型を試作して予め実験的に又は数値解析により選定することが可能である。 If the length L of the cylindrical magnetic plate group 5 in the direction of the axis M is set to be twice or more the diameter D of the annular magnetic plate 4, the cylindrical magnetic plate group 5 has a length as shown in FIG. The phase distribution in the axial direction near the center can be made gentle. Therefore, the separation allowable range in the direction of the axis M in the cylindrical magnetic plate group 5 that can detect the internal magnetic field Be with the phase difference δ within the allowable range (for example, 10 degrees or less) with respect to the target position P (for example, FIG. 4B). 1/6) of the axial length L shown in FIG. 6 and the magnetic field sensor 14 is provided on the plane Q parallel to the annular magnetic plate 4 within the range of allowable separation (L / 6) from the target position P. Therefore, it is possible to avoid a large performance deterioration of the active magnetic shield due to the phase difference δ of the internal magnetic field Be. Such an allowable distance in the direction of the axis M can be searched and selected in advance in the field, but a model of the cylindrical magnetic plate group 5 as shown in FIG. Or by numerical analysis.
更に好ましくは、筒型磁性板群５の軸線Ｍ方向の長さＬの環状磁性板４の径Ｄに対する比率（Ｌ／Ｄ）を十分に大きし、ほぼ一様な位相分布が得られる領域を軸線方向（図示例ではＺ軸方向）に拡大する。筒型磁性板群５のような開放型シールド構造では、従来から比率（Ｌ／Ｄ）を十分に大きく（例えばＬ／Ｄ＞１０）とすると、磁気シールド性能がほぼ一定の軸線中央付近の領域が軸線方向に拡大する（端部を除き無限長の筒状体と見なせる）ことが知られている。本発明者は、そのような磁気シールド性能がほぼ一定の領域では、位相分布もほぼ一定となっていることを実験的に見出した。一様な位相分布が得られる領域を拡大することにより、アクティブ磁気シールドのセンサ位置Ｓの選択の自由度を更に高めることができる。 More preferably, the ratio of the length L of the cylindrical magnetic plate group 5 in the direction of the axis M to the diameter D of the annular magnetic plate 4 is sufficiently large (L / D), and a region in which a substantially uniform phase distribution can be obtained. It expands in the axial direction (Z-axis direction in the illustrated example). In an open shield structure such as the cylindrical magnetic plate group 5, if the ratio (L / D) is conventionally sufficiently large (for example, L / D> 10), the magnetic shield performance is a region near the center of the axis that is substantially constant. Is known to expand in the axial direction (can be regarded as an infinitely long cylindrical body excluding the ends). The inventor has experimentally found that the phase distribution is substantially constant in such a region where the magnetic shield performance is substantially constant. By expanding the region where a uniform phase distribution can be obtained, the degree of freedom in selecting the sensor position S of the active magnetic shield can be further increased.
こうして本発明の目的である「シールド対象位置とセンサ位置とが離れていてもシールド性能の劣化を防止できる外乱磁場の複合型磁気シールド構築方法」の提供を達成することができる。 In this way, it is possible to provide the “method for constructing a composite magnetic shield with a disturbance magnetic field that can prevent the deterioration of the shield performance even if the shield target position and the sensor position are separated”, which is an object of the present invention.
図２は、軸線Ｍと交差する筒型磁性板群５の両端面に磁気シールド面８を配置した本発明の他の実施例を示す。上述したように、筒型磁性板群５の軸線Ｍ方向の長さＬが環状磁性板４の径Ｄの２倍未満であると、筒型磁性板群５の端面からの到来外乱磁場Ｂｏの影響によって内部磁場Ｂｅの位相分布が影響を受けるおそれがある。図示例のように、型磁性板群５の両端面にヨーク状の磁気シールド面８を配置し、いわば筒型磁性板群５の両端面に磁気シールド面８の蓋を設けることで、端面の到来外乱磁場Ｂｏの影響を防止することができる。磁気シールド面８を配置する場合は、図６（Ａ）のように大きな経路の渦電流が誘導されないように、到来外乱磁場Ｂｏの垂直に入射する磁気シールド面８の面積をできるだけ小さくすることが望ましい。例えば、筒型磁性板群５の両端面をパーマロイ、電磁鋼板等の磁性薄板６（図８（Ａ）参照）で覆うことにより密閉型の磁気シールド面８とし、又は両端面と平行にシールド簾体（図７（Ａ）参照）を配置して開放型の磁気シールド面８とすることができる。 FIG. 2 shows another embodiment of the present invention in which magnetic shield surfaces 8 are arranged on both end faces of the cylindrical magnetic plate group 5 intersecting the axis M. In FIG. As described above, if the length L in the axis M direction of the cylindrical magnetic plate group 5 is less than twice the diameter D of the annular magnetic plate 4, the incoming disturbance magnetic field Bo from the end face of the cylindrical magnetic plate group 5 is reduced. The phase distribution of the internal magnetic field Be may be affected by the influence. As shown in the illustrated example, yoke-shaped magnetic shield surfaces 8 are arranged on both end surfaces of the mold magnetic plate group 5, and so to speak, end plates of the magnetic shield surface 8 are provided on both end surfaces of the cylindrical magnetic plate group 5. The influence of the incoming disturbance magnetic field Bo can be prevented. When the magnetic shield surface 8 is arranged, the area of the magnetic shield surface 8 that is perpendicularly incident to the incoming disturbance magnetic field Bo can be made as small as possible so that an eddy current in a large path is not induced as shown in FIG. desirable. For example, the both ends of the cylindrical magnetic plate group 5 are covered with a magnetic thin plate 6 (see FIG. 8A) such as permalloy or an electromagnetic steel plate to form a sealed magnetic shield surface 8 or a shield plate parallel to both end surfaces. A body (see FIG. 7A) can be arranged to form an open type magnetic shield surface 8.
１…複合型磁気シールド構造 ２…帯状磁性板
３…磁気シールド簾体 ４…環状磁性板
５…筒型磁性板群（開放型磁気シールド）
６…磁性板 ７…密閉型磁気シールド
９…重ね合わせ部
１０…アクティブ型磁気シールド １２…補償コイル
１４…磁気センサ １６…制御装置（コンピュータ）
２０…シールド対象機器（嫌磁気装置）
Ｂｏ…到来外乱磁場 Ｂｅ…内部磁場
Ｃ…長手方向中心軸 Ｄ…環状磁性板の径
ｄ…環状磁性板の相互間隔 ｅ…渦電流の起電力
Ｆ…シールド簾面 Ｇ…伝達関数
Ｌ…筒型磁性板群の軸線方向長さ Ｍ…到来外乱磁場の方向と垂直な軸線
Ｐ…シールド対象位置 Ｑ…環状磁性板の配置平面
Ｒ…シールド対象空間
Ｓ…センサ位置 Ｗ…環状磁性板の幅
DESCRIPTION OF SYMBOLS 1 ... Composite type magnetic shield structure 2 ... Strip | belt-shaped magnetic board 3 ... Magnetic shield housing 4 ... Annular magnetic board 5 ... Cylindrical magnetic board group (open type magnetic shield)
DESCRIPTION OF SYMBOLS 6 ... Magnetic board 7 ... Sealing type magnetic shield 9 ... Overlapping part 10 ... Active type magnetic shield 12 ... Compensation coil 14 ... Magnetic sensor 16 ... Control apparatus (computer)
20 ... Shield target device (magnetomagnetic device)
Bo ... disturbance magnetic field Be ... internal magnetic field C ... longitudinal center axis D ... annular magnetic plate diameter d ... mutual distance between annular magnetic plates e ... eddy current electromotive force F ... shield surface G ... transfer function L ... cylindrical type Length of magnetic plate group in axial direction M: Axis P perpendicular to direction of incoming disturbance magnetic field P: Shield target position Q: Placement plane R of annular magnetic plate S: Target space S: Sensor position W: Width of annular magnetic plate
Claims (5)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2010184215A JP5592193B2 (en) | 2010-08-19 | 2010-08-19 | Method of constructing a composite magnetic shield for disturbance magnetic fields |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2010184215A JP5592193B2 (en) | 2010-08-19 | 2010-08-19 | Method of constructing a composite magnetic shield for disturbance magnetic fields |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2012043998A JP2012043998A (en) | 2012-03-01 |
| JP5592193B2 true JP5592193B2 (en) | 2014-09-17 |
Family
ID=45899963
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2010184215A Expired - Fee Related JP5592193B2 (en) | 2010-08-19 | 2010-08-19 | Method of constructing a composite magnetic shield for disturbance magnetic fields |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP5592193B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10889367B2 (en) * | 2017-04-24 | 2021-01-12 | Pratt & Whitney Canada Corp. | Feedback system for pitch-adjustable blades of aircraft bladed rotor |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009175067A (en) * | 2008-01-28 | 2009-08-06 | Shimizu Corp | Active magnetic shield device and active magnetic shielding method |
| JP4919433B2 (en) * | 2008-03-17 | 2012-04-18 | 鹿島建設株式会社 | Magnetic shield blade material and method of manufacturing the same |
| JP5131758B2 (en) * | 2008-03-25 | 2013-01-30 | 鹿島建設株式会社 | Active magnetic shield performance evaluation method and apparatus |
-
2010
- 2010-08-19 JP JP2010184215A patent/JP5592193B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2012043998A (en) | 2012-03-01 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Lee et al. | Calculation of magnetic field noise from high-permeability magnetic shields and conducting objects with simple geometry | |
| CN102680567B (en) | Vortex finder | |
| JP5328599B2 (en) | Composite magnetic shield structure and system | |
| JP2012225921A (en) | Current sensor with magnetic core | |
| US9655291B2 (en) | Multilayer magnetic shield | |
| JP4857061B2 (en) | Gradient magnetic field coil and nuclear magnetic resonance tomography apparatus using the same | |
| JP5930400B2 (en) | Open magnetic shield structure with conductor circuit | |
| JP5592193B2 (en) | Method of constructing a composite magnetic shield for disturbance magnetic fields | |
| JP2012117839A (en) | Magnetic shield device and current sensor device using the same | |
| JP5900014B2 (en) | Magnetic shield device | |
| JP6628407B2 (en) | Low leakage shaking type open magnetic shield structure | |
| JP5630861B2 (en) | Disturbance magnetic field measurement sensor and active magnetic shield system | |
| JP2016061572A (en) | Magnetic field sensor | |
| US11320504B2 (en) | Open-type magnetic resonance imaging apparatus | |
| JP6599258B2 (en) | Shaking type open magnetic shield structure | |
| JP2002102205A (en) | Magnetic resonace imaging apparatus | |
| JP2024080721A (en) | Magnetic shield device and magnetic shield panel | |
| JP2017135353A (en) | Shaking open type magnetic shield structure | |
| JP3103439B2 (en) | Proximity installation method of a plurality of nuclear magnetic resonance apparatuses | |
| JP6906473B2 (en) | Magnetic field compensator | |
| JP5574809B2 (en) | Wire rope flaw detector and detection method using wire rope flaw detector | |
| US11525661B2 (en) | Magnetic unit, position detection apparatus, and magnetic member | |
| JPH01109799A (en) | Magnetic shielding device | |
| JPH0373598A (en) | Magnetic shielding device | |
| JPH06167583A (en) | Compensation method for leaked magnetic field at an open end of magnetic shield |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20130216 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20131129 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20131224 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20140218 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20140725 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20140731 |
|
| R150 | Certificate of patent or registration of utility model |
Ref document number: 5592193 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| LAPS | Cancellation because of no payment of annual fees |