JP5139822B2 - Magnetic field probe - Google Patents

Magnetic field probe Download PDF

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JP5139822B2
JP5139822B2 JP2008019294A JP2008019294A JP5139822B2 JP 5139822 B2 JP5139822 B2 JP 5139822B2 JP 2008019294 A JP2008019294 A JP 2008019294A JP 2008019294 A JP2008019294 A JP 2008019294A JP 5139822 B2 JP5139822 B2 JP 5139822B2
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magnetic field
anisotropic magnetoresistive
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permanent magnet
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JP2009180596A (en
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信助 望月
栄男 小関
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Kohden Co Ltd
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Description

本発明は、永久磁石、金属材料の残留磁気、コイル等から発生する空間の磁界など磁界の強さ、方向を検出する磁界プローブに関するものである。   The present invention relates to a magnetic field probe for detecting the strength and direction of a magnetic field such as a permanent magnet, residual magnetism of a metal material, and a magnetic field in a space generated from a coil.

電界の影響を排除し磁界のみを検出するための装置として磁界プローブが存在する。発生源が発生する電磁界には、放射電磁界以外に静電磁界、誘導電磁界の成分がある。発生源の近傍ではこれらも電磁雑音として影響する。磁界プローブは、発生源から略１／６波長以上離れたところの放射電磁界による電磁雑音を測定する目的や、その発生源を特定する目的で主に使用されるものである。この磁界プローブの種類としては、コイルをループ状にしたループアンテナを使用するもの（特許文献１、２）、発生源の近傍での電磁雑音を測定する技術としてのホールプローブ、異方性磁気抵抗素子とループアンテナとを組み合わせた磁界プローブ（特許文献３）などが存在する。
特開２００２−１５６４３０号公報 特開２００４−０８５４６５号公報 特開２００１−２８９８９３号公報 Magnetic field probes exist as devices for eliminating the influence of an electric field and detecting only a magnetic field. The electromagnetic field generated by the generation source includes components of an electrostatic magnetic field and an induction electromagnetic field in addition to the radiated electromagnetic field. These also affect electromagnetic noise in the vicinity of the source. The magnetic field probe is mainly used for the purpose of measuring electromagnetic noise due to a radiated electromagnetic field at a distance of about 1/6 wavelength or more from a generation source and for the purpose of specifying the generation source. The types of magnetic field probes include those using a loop antenna having a coiled loop (Patent Documents 1 and 2), a Hall probe as a technique for measuring electromagnetic noise in the vicinity of the source, and an anisotropic magnetoresistance. There is a magnetic field probe (Patent Document 3) in which an element and a loop antenna are combined.
JP 2002-156430 A JP 2004-085465 A JP 2001-289893 A

前記特許文献１、２に記載のループアンテナを用いた磁界プローブの場合には、コイルからの出力は微分波形であり、すなわち誘起電圧が磁界の周波数に依存するため、１００ｋＨｚ以下の低周波の磁界では、ループの有効断面積を大きくするか巻き数を多くするかによって感度を大きくする必要がある。よって形状が大きくなり局所的な磁界を測定することが困難という問題がある。
詳細は省略するが、誘起電圧の最大値Ｖ０と、コイルの巻数ｎ、コイルの断面積Ｓ、周波数ｆでコイルに加わる磁界の最大値Ｂ０との間には、Ｖ０＝２πｆｎＳＢ０の関係が成り立つ。例えば、ｆ＝１００Ｈｚ、Ｂ０＝０．００２Ｔ、ｎ＝１０としたときに、誘起電圧の最大値Ｖ０として０．０９８Ｖを得るためには、コイルの半径を約５ｃｍとしなければならなくなってしまう。 In the case of the magnetic field probe using the loop antenna described in Patent Documents 1 and 2, since the output from the coil is a differential waveform, that is, the induced voltage depends on the frequency of the magnetic field, a low frequency magnetic field of 100 kHz or less. Then, it is necessary to increase the sensitivity depending on whether the effective area of the loop is increased or the number of turns is increased. Therefore, there is a problem that the shape becomes large and it is difficult to measure a local magnetic field.
Although not described in detail, V 0 = 2πfnSB 0 is between the maximum value V 0 of the induced voltage and the maximum value B 0 of the magnetic field applied to the coil at the number of turns n of the coil, the cross-sectional area S of the coil, and the frequency f. A relationship is established. For example, when f = 100 Hz, B 0 = 0.002T, and n = 10, in order to obtain 0.098V as the maximum value V 0 of the induced voltage, the radius of the coil must be about 5 cm. End up.

発生源の近傍での電磁雑音を測定する技術としてのホールプローブの場合は、検出部としてホール素子を使用しているため、永久磁石のような静磁界から１０ｋＨｚの低周波の磁界まで検出が可能であり、磁界範囲も数百ｍＴまで可能であり広い。しかしながら、１０ｋＨｚ以上の周波数域帯域の磁界検出が物性上困難という問題点がある。またホール素子では、磁界分解能として０．０５ｍＴ以下は難しいという問題点がある。
すなわち、前記ループアンテナを用いた磁界プローブやホールプローブでは、発生源の近傍での電磁雑音について、１００ｋＨｚ以下の周波数全域をカバーする効率的な測定を行うことは困難であるという問題があった。 In the case of a Hall probe as a technique for measuring electromagnetic noise in the vicinity of the generation source, since a Hall element is used as a detection unit, detection is possible from a static magnetic field such as a permanent magnet to a low-frequency magnetic field of 10 kHz. The magnetic field range can be several hundred mT and is wide. However, there is a problem that it is difficult to detect a magnetic field in a frequency band of 10 kHz or more. In addition, the Hall element has a problem that it is difficult to have a magnetic field resolution of 0.05 mT or less.
That is, the magnetic field probe and the hall probe using the loop antenna have a problem in that it is difficult to perform efficient measurement covering the entire frequency range of 100 kHz or less with respect to electromagnetic noise near the generation source.

これに対して、特許文献３に記載されたような異方性磁気抵抗素子とループアンテナとを組み合わせた磁界プローブでは、静磁界から１００ｋＨｚ以下の低周波数帯域の磁界を異方性磁気抵抗素子によって測定し、１００ｋＨｚ以上の周波数の磁界をループアンテナによって測定するため、幅広い周波数に対応した磁界検出が可能である。一般に、異方性磁気抵抗素子はＮｉ、Ｆｅ、Ｃｏ等の強磁性金属を主成分とする合金の薄膜で構成され、磁界の強さ方向に応じて抵抗値が変化する。強磁性薄膜金属の応答は、ΔＲ／Ｒ０（ΔＲ＝強磁性薄膜金属の抵抗の変化、Ｒ０＝強磁性薄膜金属の公称抵抗）として測定される。
図９（ａ）、（ｂ）に示すように、電流の方向に対して垂直方向の磁界の強さ（Ｈ）とΔＲ／Ｒ０との関係は、釣鐘形状（ΔＲ／Ｒ０はＨ２に略比例して減少）のグラフとなる。 On the other hand, in a magnetic field probe that combines an anisotropic magnetoresistive element and a loop antenna as described in Patent Document 3, a magnetic field in a low frequency band of 100 kHz or less from a static magnetic field is generated by an anisotropic magnetoresistive element. Since a magnetic field having a frequency of 100 kHz or higher is measured by the loop antenna, magnetic field detection corresponding to a wide range of frequencies is possible. In general, an anisotropic magnetoresistive element is formed of a thin film of an alloy mainly composed of a ferromagnetic metal such as Ni, Fe, or Co, and the resistance value changes according to the direction of the magnetic field strength. The response of the ferromagnetic thin film metal is measured as ΔR / R 0 (ΔR = change in resistance of the ferromagnetic thin film metal, R 0 = nominal resistance of the ferromagnetic thin film metal).
As shown in FIGS. 9A and 9B, the relationship between the strength (H) of the magnetic field perpendicular to the direction of the current and ΔR / R 0 is the bell shape (ΔR / R 0 is H 2). It is a graph of (decrease substantially in proportion to).

この異方性磁気抵抗素子とループアンテナとを組み合わせた磁界プローブの問題点は、図９（ｂ）に示すように動作点がゼロ磁界にあるため、強磁性薄膜金属の材質、膜厚、膜幅を検討し感度を上昇させても、場合によっては０．０１ｍＴの磁界分解能を得る事は難しいということである。さらに、図９（ｃ）は同図（ｂ）のゼロ磁界近辺の拡大図であるが、この図９（ｃ）に示すように、動作点がゼロ磁界の場合には必ずヒステリシスが生じるため、正確な検出が出来ない、若しくは、ヒステリシスによる影響を除いた結果を得るための処理回路が必要になり構成が複雑になるという問題がある。   The problem of the magnetic field probe combining this anisotropic magnetoresistive element and the loop antenna is that the operating point is a zero magnetic field as shown in FIG. Even if the width is examined and the sensitivity is increased, in some cases, it is difficult to obtain a magnetic field resolution of 0.01 mT. Further, FIG. 9C is an enlarged view of the vicinity of the zero magnetic field in FIG. 9B. However, as shown in FIG. 9C, hysteresis always occurs when the operating point is a zero magnetic field. There is a problem that accurate detection cannot be performed, or a processing circuit for obtaining a result excluding the influence of hysteresis is required, and the configuration becomes complicated.

本発明は、上記問題点に鑑みなされたものであり、静磁界からＭＨｚの周波数帯域において磁界の強さと方向を高精度に検出し、小型で安価で簡単な回路で実現できる磁界プローブを提供することを目的とするものである。   The present invention has been made in view of the above problems, and provides a magnetic field probe that can detect the strength and direction of a magnetic field with high accuracy in a frequency band from a static magnetic field to MHz and can be realized with a small, inexpensive, and simple circuit. It is for the purpose.

本発明の請求項１は、空間の磁界の強度と方向を検出する磁界プローブであって、異方性磁気抵抗素子が複数形成された基板と磁極面の中心から放射状に磁力線が放出される永久磁石とを具備したセンサと、導電率の高い素材で被われている配線部を備えた前記センサを固定するためのセンサ固定基板とからなり、前記センサは、前記永久磁石の磁極面に平行な基板上に、前記永久磁石の磁極面の磁気的中心を原点としてＸ軸及びＹ軸上の原点から同一距離の位置に４つの領域を形成し、この各々の領域に対して、軸線と４５°（又は１３５°）の角度をなす方向に延伸した異方性磁気抵抗素子をそれぞれ形成して、合計４つの異方性磁気抵抗素子から構成されるようにし、前記４つの異方性磁気抵抗素子は、対角に位置する同士を結線してその間から出力をとるようにしたことを特徴とする磁界プローブである。 Claim 1 of the present invention is a magnetic field probe for detecting the strength and direction of the magnetic field space, a permanent anisotropic magnetoresistive element force rays are emitted radially from the center of a plurality formed substrate and the magnetic pole surface A sensor having a magnet, and a sensor fixing substrate for fixing the sensor having a wiring portion covered with a material having high conductivity, the sensor being parallel to the magnetic pole surface of the permanent magnet. Four regions are formed on the substrate at the same distance from the origin on the X axis and the Y axis with the magnetic center of the magnetic pole surface of the permanent magnet as the origin. An anisotropic magnetoresistive element extended in a direction forming an angle of (or 135 °) is formed, respectively, so as to be composed of a total of four anisotropic magnetoresistive elements , and the four anisotropic magnetoresistive elements Are connected diagonally to each other. It is a magnetic field probe characterized by taking an output from between .

本発明の請求項２は、空間の磁界の強度と方向を検出する磁界プローブであって、異方性磁気抵抗素子が複数形成された基板と磁極面の中心から放射状に磁力線が放出される永久磁石とを具備したセンサと、導電率の高い素材で被われている配線部を備えた前記センサを固定するためのセンサ固定基板とからなり、前記センサは、前記永久磁石の磁極面に平行な基板上に、前記永久磁石の磁極面の磁気的中心を原点としてＸ軸及びＹ軸上の原点から同一距離の位置に４つの領域を形成し、この各々の領域に対して、互いの延伸する方向が成す角度が垂直でかつ軸線と４５°（又は１３５°）の角度をなす方向に延伸した２つの異方性磁気抵抗素子を隣接させて形成して、合計８つの異方性磁気抵抗素子から構成されることを特徴とする磁界プローブである。 According to a second aspect of the present invention , there is provided a magnetic field probe for detecting the intensity and direction of a magnetic field in a space, wherein a magnetic field line is emitted radially from the center of a substrate on which a plurality of anisotropic magnetoresistive elements are formed and a magnetic pole surface. A sensor having a magnet, and a sensor fixing substrate for fixing the sensor having a wiring portion covered with a material having high conductivity, the sensor being parallel to the magnetic pole surface of the permanent magnet. Four regions are formed on the substrate at the same distance from the origin on the X axis and the Y axis with the magnetic center of the magnetic pole surface of the permanent magnet as the origin, and the regions are extended with respect to each other. A total of eight anisotropic magnetoresistive elements are formed by adjoining two anisotropic magnetoresistive elements extending in a direction in which the direction is perpendicular to the axis and forming an angle of 45 ° (or 135 °) with the axis. Magnetic field professional characterized by comprising It is a curve.

本発明の請求項３は、請求項１又は２に加えて、前記異方性磁気抵抗素子が複数形成された基板は、低透磁率でかつ絶縁体であることを特徴とする磁界プローブである。 A third aspect of the present invention is the magnetic field probe according to the first or second aspect , wherein the substrate on which a plurality of the anisotropic magnetoresistive elements are formed has a low magnetic permeability and is an insulator. .

請求項１記載の発明によれば、前記センサは、前記永久磁石の磁極面に平行な基板上に、前記永久磁石の磁極面の磁気的中心を原点としてＸ軸及びＹ軸上の原点から同一距離の位置に４つの領域を形成し、この各々の領域に対して、軸線と４５°（又は１３５°）の角度をなす方向に延伸した異方性磁気抵抗素子をそれぞれ形成して、合計４つの異方性磁気抵抗素子から構成されるようにし、前記４つの異方性磁気抵抗素子は、対角に位置する同士を結線してその間から出力をとるようにしたので、磁界の方向を精度良く検出することが可能となる。 According to the first aspect of the present invention, the sensor is the same on the substrate parallel to the magnetic pole surface of the permanent magnet from the origin on the X axis and the Y axis with the magnetic center of the magnetic pole surface of the permanent magnet as the origin. Four regions are formed at the position of the distance, and anisotropic magnetoresistive elements extending in a direction forming an angle of 45 ° (or 135 °) with the axis are formed for each region, and a total of 4 regions are formed. Because the four anisotropic magnetoresistive elements are connected to each other diagonally and output is taken between them , the direction of the magnetic field is accurately determined. It is possible to detect well.

請求項２記載の発明によれば、前記センサは、前記永久磁石の磁極面に平行な基板上に、前記永久磁石の磁極面の磁気的中心を原点としてＸ軸及びＹ軸上の原点から同一距離の位置に４つの領域を形成し、この各々の領域に対して、互いの延伸する方向が成す角度が垂直でかつ軸線と４５°（又は１３５°）の角度をなす方向に延伸した２つの異方性磁気抵抗素子を隣接させて形成して、合計８つの異方性磁気抵抗素子から構成されるようにしたので、８つの異方性磁気抵抗素子をホイートストンブリッジ構成とすることで出力が２倍となり、かつ２次高調波成分が打ち消され出力の直線域が広がる。 According to a second aspect of the present invention, the sensor is the same on the substrate parallel to the magnetic pole surface of the permanent magnet from the origin on the X axis and the Y axis with the magnetic center of the magnetic pole surface of the permanent magnet as the origin. Four regions are formed at distance positions, and for each of the two regions, the angle formed by the direction in which the layers extend is perpendicular to each other, and the two extending in the direction that forms an angle of 45 ° (or 135 °) with the axis Since the anisotropic magnetoresistive elements are formed adjacent to each other so as to be composed of a total of eight anisotropic magnetoresistive elements, the output can be obtained by configuring the eight anisotropic magnetoresistive elements in a Wheatstone bridge configuration. The second harmonic component is canceled out and the output linear range is expanded.

請求項３記載の発明によれば、前記異方性磁気抵抗素子が複数形成された基板を低透磁率でかつ絶縁体である材料、例えば、セラミック又はガラス材で形成することで、高周波数帯域において磁界プローブ自身が発生する渦電流等を抑制することができる。 According to a third aspect of the present invention, a substrate on which a plurality of the anisotropic magnetoresistive elements are formed is formed of a material having a low magnetic permeability and an insulator, for example, a ceramic or glass material, so that a high frequency band is obtained. The eddy current generated by the magnetic field probe itself can be suppressed.

本発明による磁界プローブは、空間の磁界の強度と方向を検出する磁界プローブであって、異方性磁気抵抗素子が複数形成された基板と永久磁石とを具備したセンサと、導電率の高い素材で被われている配線部を備えた前記センサを固定するためのセンサ固定基板とからなることを特徴とするものであり、前記センサは、前記永久磁石の磁極面に平行な基板上に、前記永久磁石の磁極面の磁気的中心を原点としてＸ軸及びＹ軸上の原点から同一距離の位置に４つの領域を形成し、この各々の領域に対して、互いの延伸する方向が成す角度が垂直でかつ軸線と４５°（又は１３５°）の角度をなす方向に延伸した２つの異方性磁気抵抗素子を隣接させて形成して、合計８つの異方性磁気抵抗素子から構成されることを特徴とするものである。以下、図面に基づいて詳細な説明を行う。   A magnetic field probe according to the present invention is a magnetic field probe for detecting the intensity and direction of a magnetic field in a space, and includes a sensor having a substrate on which a plurality of anisotropic magnetoresistive elements are formed and a permanent magnet, and a material having high conductivity. A sensor fixing substrate for fixing the sensor provided with the wiring portion covered by the sensor, wherein the sensor is disposed on the substrate parallel to the magnetic pole surface of the permanent magnet. Four regions are formed at the same distance from the origin on the X-axis and the Y-axis with the magnetic center of the magnetic pole surface of the permanent magnet as the origin, and the angle formed by the extending direction of each region is relative to each region. Two anisotropic magnetoresistive elements that are perpendicular to each other and extend in a direction that forms an angle of 45 ° (or 135 °) with the axis are formed adjacent to each other, and are composed of a total of eight anisotropic magnetoresistive elements. It is characterized by. Hereinafter, a detailed description will be given based on the drawings.

本発明の実施の形態について説明する。図１（ａ）は本発明の磁界プローブ１０の構成を表した斜視図であり、図１（ｂ）は側面図である。異方性磁気抵抗素子が複数形成された基板１２の上に永久磁石１３が具備されたセンサ１１と、導電率の高い素材で出来たシールド膜１８で被われている配線部１５を備えたセンサ固定基板１４から構成されている。センサ１１とセンサ固定基板１４は、配線端部１６とセンサ１１との間を金線１７にてワイヤーボンディングして電気的に接続している。図面上は表現されていないが、各配線端部１６と配線１５は電気的に導通している。本図での図解は省略してあるが、センサ１１は一般的な電子部品材であるシリコン、エポキシ、ウレタン樹脂の単層若しくは多層にて保護されている。センサ固定基板１４は、ガラスエポキシ材若しくはＦＰＣ（フレキシブルプリント基板）からなり、配線部１５はＣｕ材からなり、配線端部１６はＮｉ鍍金とＡｕ鍍金が施されている。シールド膜１８は、例えば銅薄膜で構成されており、このシールド膜１８と配線部１５との間は絶縁されている。配線部１５が導電率の高い素材で被われていることで、電界の影響を排除することが可能となる。   Embodiments of the present invention will be described. FIG. 1A is a perspective view showing a configuration of a magnetic field probe 10 of the present invention, and FIG. 1B is a side view. A sensor having a sensor 11 having a permanent magnet 13 on a substrate 12 on which a plurality of anisotropic magnetoresistive elements are formed, and a wiring portion 15 covered with a shield film 18 made of a material having high conductivity. It is composed of a fixed substrate 14. The sensor 11 and the sensor fixing substrate 14 are electrically connected by wire bonding between the wiring end 16 and the sensor 11 with a gold wire 17. Although not shown in the drawing, each wiring end 16 and the wiring 15 are electrically connected. Although illustration in this figure is omitted, the sensor 11 is protected by a single layer or multiple layers of silicon, epoxy, or urethane resin, which are general electronic component materials. The sensor fixing substrate 14 is made of a glass epoxy material or FPC (flexible printed circuit board), the wiring portion 15 is made of a Cu material, and the wiring end portion 16 is plated with Ni and Au. The shield film 18 is made of, for example, a copper thin film, and the shield film 18 and the wiring portion 15 are insulated. Since the wiring part 15 is covered with a material having high conductivity, it is possible to eliminate the influence of the electric field.

図１では基板１２の上に永久磁石１３を配置してセンサ１１を形成しているが、図２（ａ）又は（ｂ）に示すように、センサ固定基板１４の表若しくは裏に穴を空けて永久磁石１３を埋め込んだものも本発明の他の実施例として挙げることができる。   In FIG. 1, the sensor 11 is formed by arranging the permanent magnet 13 on the substrate 12. However, as shown in FIG. 2A or 2B, holes are formed in the front or back of the sensor fixing substrate 14. Further, the one in which the permanent magnet 13 is embedded can be cited as another embodiment of the present invention.

図３（ａ）は、図１におけるセンサ１１の異方性磁気抵抗素子の構成に関する実施例１であり、センサ１１における永久磁石１３と異方性磁気抵抗素子との位置関係を示した図である。異方性磁気抵抗素子を形成した基板１２は、永久磁石１３の磁極面に平行で、永久磁石１３の磁極の中心に基板１２の中心が一致するように配置される。基板１２上のＸ軸及びＹ軸上における中心（原点）から同一距離の４つの領域には、軸線に対して４５°（１３５°）の角度をなす方向に延伸した異方性磁気抵抗素子１９、２０、２１、２２がそれぞれ形成されている。異方性磁気抵抗素子（１９〜２２）は基板１２上で、図３（ｂ）に示すように結線される。   FIG. 3A is a first embodiment relating to the configuration of the anisotropic magnetoresistive element of the sensor 11 in FIG. is there. The substrate 12 on which the anisotropic magnetoresistive element is formed is disposed so that it is parallel to the magnetic pole surface of the permanent magnet 13 and the center of the substrate 12 coincides with the center of the magnetic pole of the permanent magnet 13. Anisotropic magnetoresistive element 19 extended in a direction forming an angle of 45 ° (135 °) with respect to the axis in four regions on the substrate 12 at the same distance from the center (origin) on the X and Y axes. , 20, 21 and 22 are formed respectively. The anisotropic magnetoresistive elements (19 to 22) are connected on the substrate 12 as shown in FIG.

図４（ａ）は、図１におけるセンサ１１の異方性磁気抵抗素子の構成に関する実施例２であり、センサ１１における永久磁石１３と異方性磁気抵抗素子との位置関係を示した図である。異方性磁気抵抗素子を形成した基板１２は、永久磁石１３の磁極面に平行で、かつ永久磁石１３の磁極の中心に基板１２の中心が一致するように配置される。基板１２上のＸ軸及びＹ軸上における中心（原点）から同一距離の４つの領域にはそれぞれ、互いの延伸する方向が成す角度が垂直でかつ軸線に対して４５°（１３５°）の角度をなす方向に延伸した２つの隣接する異方性磁気抵抗素子が形成され、合計８つの異方性磁気抵抗素子２３ａ、２３ｂ、２４ａ、２４ｂ、２５ａ、２５ｂ、２６ａ、２６ｂが形成されている。異方性磁気抵抗素子（２３ａ〜２６ａ及び２３ｂ〜２６ｂ）は基板１２上で、図４（ｂ）に示すように、ホイートストンブリッジを構成するように結線される。   FIG. 4A is a second embodiment relating to the configuration of the anisotropic magnetoresistive element of the sensor 11 in FIG. 1, and is a diagram showing the positional relationship between the permanent magnet 13 and the anisotropic magnetoresistive element in the sensor 11. is there. The substrate 12 on which the anisotropic magnetoresistive element is formed is arranged so that it is parallel to the magnetic pole surface of the permanent magnet 13 and the center of the substrate 12 coincides with the center of the magnetic pole of the permanent magnet 13. In each of the four regions on the substrate 12 at the same distance from the center (origin) on the X-axis and the Y-axis, the angle formed by the extending direction of each other is vertical and an angle of 45 ° (135 °) with respect to the axis Two adjacent anisotropic magnetoresistive elements extending in the direction of forming are formed, and a total of eight anisotropic magnetoresistive elements 23a, 23b, 24a, 24b, 25a, 25b, 26a, 26b are formed. The anisotropic magnetoresistive elements (23a to 26a and 23b to 26b) are connected to form a Wheatstone bridge on the substrate 12, as shown in FIG. 4B.

次に、異方性磁気抵抗素子に常時バイアス磁界を印加することで特性改善がなされる原理を説明する。図９（ａ）で示した異方性磁気抵抗素子の抵抗変化において、常時バイアス磁界を印加することにより特性を改善する方法は、公知技術（例えば、特開昭５８−０１６５８０号公報）として知られている。
すなわち、図９（ａ）に示す異方性磁気抵抗素子のＹ方向にバイアス磁界を印加することで、図９（ｃ）でのヒステリシスが解消され、図９（ａ）に示す異方性磁気抵抗素子のＸ方向にバイアス磁界を印加することで、図５に示すように動作点が０（ゼロ）磁界からＰ点磁界に移動する。 Next, the principle of improving the characteristics by constantly applying a bias magnetic field to the anisotropic magnetoresistive element will be described. In the resistance change of the anisotropic magnetoresistive element shown in FIG. 9A, a method for improving the characteristics by constantly applying a bias magnetic field is known as a known technique (for example, Japanese Patent Laid-Open No. 58-016580). It has been.
That is, by applying a bias magnetic field in the Y direction of the anisotropic magnetoresistive element shown in FIG. 9A, the hysteresis in FIG. 9C is eliminated, and the anisotropic magnetism shown in FIG. By applying a bias magnetic field in the X direction of the resistance element, the operating point moves from a 0 (zero) magnetic field to a P point magnetic field as shown in FIG.

発生源から発生する磁界を入力磁界とした場合の異方性磁気抵抗素子の抵抗変化を表す検出信号は、動作点がゼロ磁界の場合は図６（ａ）のような変化となり、動作点がＰ点に移動した場合は図６（ｂ）のような変化となる。この図６からも分かるように、図６（ａ）より図６（ｂ）の方が、釣鐘形状の波形（２次曲線波形）のうち感度の高い線形に近い波形部分に動作点が移動したことによって、同じ磁界変化であっても抵抗値の変化幅が大きくなるため、磁界分解能が向上することが分かる。これにより、０．０１ｍＴ以下の磁界においても測定が可能となる。   The detection signal indicating the resistance change of the anisotropic magnetoresistive element when the magnetic field generated from the generation source is an input magnetic field changes as shown in FIG. 6A when the operating point is a zero magnetic field. When moved to the point P, the change is as shown in FIG. As can be seen from FIG. 6, in FIG. 6 (b), the operating point has moved to a highly sensitive linear portion of the bell-shaped waveform (secondary curve waveform) rather than FIG. 6 (a). Accordingly, it can be understood that the magnetic field resolution is improved because the change width of the resistance value is increased even with the same magnetic field change. As a result, measurement is possible even in a magnetic field of 0.01 mT or less.

加えて本発明のバイアス磁界を印加する手段としての永久磁石について説明する。図７に示すのは、永久磁石１３の磁気ベクトルを表した模式図であり、（ａ）は斜視図、（ｂ）は底面図である。この図７（ａ）（ｂ）に示すように、永久磁石１３の磁気ベクトルは、磁極面より放射状に発生する。このとき、永久磁石１３の磁極面と基板１２の中心を重ね合わせてセンサ１１を構成しているため、図３（ａ）又は図４（ａ）に示した全ての異方性磁気抵抗素子には、延伸方向に対して４５°の方向にバイアス磁界が印加される。すなわち、先に説明した図９（ａ）におけるＸ方向とＹ方向に同時にバイアス磁界が印加されることになる。よって、ヒステリシスが改善され、かつ、磁界分解能が向上する。   In addition, a permanent magnet as means for applying a bias magnetic field according to the present invention will be described. FIG. 7 is a schematic diagram showing the magnetic vector of the permanent magnet 13, where (a) is a perspective view and (b) is a bottom view. As shown in FIGS. 7A and 7B, the magnetic vector of the permanent magnet 13 is generated radially from the magnetic pole surface. At this time, since the sensor 11 is configured by superimposing the magnetic pole surface of the permanent magnet 13 and the center of the substrate 12, all the anisotropic magnetoresistive elements shown in FIG. 3A or FIG. Is applied with a bias magnetic field in a direction of 45 ° with respect to the stretching direction. That is, the bias magnetic field is simultaneously applied in the X direction and the Y direction in FIG. 9A described above. Therefore, hysteresis is improved and magnetic field resolution is improved.

図８に示すのは、本発明の磁界プローブ１０に発生源からの磁界が入力された場合を表した模式図である。この図８の磁界プローブ１０は、図１に示したものの上面図であって、図３及び図４でのＸ軸、Ｙ軸を付記し、配線やシールド等は図から省略したものである。
入力磁界がイ、ロ、ハの方向からそれぞれ印加された場合、Ｘ軸方向に形成された異方性磁気抵抗素子の抵抗値変化とＹ軸方向に形成された異方性磁気抵抗素子の抵抗値変化には以下の関係が成り立つ。
イ：Ｘ軸方向の抵抗値変化＞Ｙ軸方向の抵抗値変化
ロ：Ｘ軸方向の抵抗値変化＝Ｙ軸方向の抵抗値変化
ハ：Ｘ軸方向の抵抗値変化＜Ｙ軸方向の抵抗値変化 FIG. 8 is a schematic diagram showing a case where a magnetic field from a generation source is input to the magnetic field probe 10 of the present invention. The magnetic field probe 10 shown in FIG. 8 is a top view of what is shown in FIG. 1, with the X-axis and Y-axis in FIGS. 3 and 4 added, and the wiring and shields omitted from the drawing.
When the input magnetic field is applied from the directions of A, B, and C, respectively, the change in the resistance value of the anisotropic magnetoresistive element formed in the X axis direction and the resistance of the anisotropic magnetoresistive element formed in the Y axis direction The following relationship holds for the value change.
B: Resistance value change in the X-axis direction> Resistance value change in the Y-axis direction
B: Resistance value change in the X-axis direction = Resistance value change in the Y-axis direction
C: Resistance value change in the X-axis direction <Resistance value change in the Y-axis direction

すなわち、実施例１又は実施例２に示すようにして基板１２上に異方性磁気抵抗素子を形成することで、入力磁界の方向が分かる。入力磁界の強さを表す振幅の大小と抵抗値変化の振幅は比例関係にある。実施例２ではホイートストンブリッジ構成になっているため、実施例１に比較して２倍の出力となり、かつ２次高調波成分が打ち消され出力の直線域が広がる。図６（ｂ）から入力磁界の周波数と同じ周波数で抵抗値変化が起こることも理解できる。   That is, by forming an anisotropic magnetoresistive element on the substrate 12 as shown in Example 1 or Example 2, the direction of the input magnetic field can be known. The magnitude of the amplitude representing the strength of the input magnetic field is proportional to the amplitude of the resistance value change. Since the second embodiment has a Wheatstone bridge configuration, the output is twice that of the first embodiment, the second harmonic component is canceled, and the linear range of the output is expanded. It can also be understood from FIG. 6B that the resistance value changes at the same frequency as the frequency of the input magnetic field.

また、基板１２を低透磁率でかつ絶縁体であるセラミック又はガラス材で形成することで、高周波数帯域において磁界プローブ１０自身が発生する渦電流等を抑制することができる。   Further, by forming the substrate 12 from a ceramic or glass material that has a low magnetic permeability and is an insulator, eddy currents generated by the magnetic field probe 10 itself in a high frequency band can be suppressed.

以上に示した本発明の磁界プローブによれば、静磁界からＭＨｚ単位の周波数帯域まで幅広く対応可能で、かつ小型でありながら磁界の強さと方向を高精度に検出することが可能となる。
本発明の磁界プローブを実際に構成する場合、異方性磁気抵抗素子を形成する基板１２は２ｍｍ×２ｍｍ程度の大きさ、バイアス磁石１３としてのフェライト焼結材はΦ１．５ｍｍ×０．３５ｍｍ程度の大きさで構成することが可能となり、前述した従来技術のループコイルの場合と異なり、周波数に依存することなく小型化が可能であるというメリットがある。また、全体を安価に構成できるというメリットもある。 According to the magnetic field probe of the present invention described above, it is possible to cope with a wide range from a static magnetic field to a frequency band of MHz, and it is possible to detect the strength and direction of the magnetic field with high accuracy while being small.
When the magnetic field probe of the present invention is actually constructed, the substrate 12 on which the anisotropic magnetoresistive element is formed has a size of about 2 mm × 2 mm, and the sintered ferrite material as the bias magnet 13 has a diameter of about 1.5 mm × 0.35 mm. Unlike the conventional loop coil described above, there is an advantage that the size can be reduced without depending on the frequency. There is also an advantage that the whole can be configured at a low cost.

（ａ）は、本発明の磁界プローブ１０の構成を表した斜視図であり、（ｂ）は、側面図である。(A) is a perspective view showing the structure of the magnetic field probe 10 of this invention, (b) is a side view. （ａ）及び（ｂ）は、図１におけるセンサ１１の他の実施例を表した模式図である。(A) And (b) is the schematic diagram showing the other Example of the sensor 11 in FIG. （ａ）は、図１におけるセンサ１１の異方性磁気抵抗素子の構成に関する実施例１であり、（ｂ）は、異方性磁気抵抗素子の接続を表した回路図である。(A) is Example 1 regarding the structure of the anisotropic magnetoresistive element of the sensor 11 in FIG. 1, (b) is a circuit diagram showing the connection of the anisotropic magnetoresistive element. （ａ）は、図１におけるセンサ１１の異方性磁気抵抗素子の構成に関する実施例２であり、（ｂ）は、異方性磁気抵抗素子の接続を表した回路図である。(A) is Example 2 regarding the structure of the anisotropic magnetoresistive element of the sensor 11 in FIG. 1, (b) is a circuit diagram showing the connection of the anisotropic magnetoresistive element. バイアス磁界を印加した場合の異方性磁気抵抗素子の動作点の移動を表した説明図である。It is explanatory drawing showing the movement of the operating point of the anisotropic magnetoresistive element at the time of applying a bias magnetic field. 発生源から発生する磁界を入力磁界とした場合の異方性磁気抵抗素子の抵抗変化を表した模式図であり、（ａ）は、動作点がゼロ磁界の場合であり、（ｂ）は、動作点がＰ点に移動した場合である。It is a schematic diagram showing the resistance change of the anisotropic magnetoresistive element when the magnetic field generated from the generation source is the input magnetic field, (a) is a case where the operating point is a zero magnetic field, (b) This is a case where the operating point moves to point P. 永久磁石１３の磁気ベクトルを表した模式図であり、（ａ）は斜視図、（ｂ）は底面図である。It is the schematic diagram showing the magnetic vector of the permanent magnet 13, (a) is a perspective view, (b) is a bottom view. 本発明の磁界プローブ１０に発生源からの磁界が入力された場合を表した模式図である。It is the schematic diagram showing the case where the magnetic field from a generation source is input into the magnetic field probe 10 of this invention. （ａ）乃至（ｃ）は、異方性磁気抵抗素子の抵抗値変化の一般的性質について説明した説明図である。(A) thru | or (c) are explanatory drawings explaining the general property of resistance value change of an anisotropic magnetoresistive element.

符号の説明Explanation of symbols

１０…磁界プローブ、１１…センサ、１２…基板、１３…永久磁石、１４…センサ固定基板、１５…配線、１６…配線端部、１７…金線、１８…シールド膜、１９〜２２…異方性磁気抵抗素子、２３ａ〜２６ａ及び２３ｂ〜２６ｂ…異方性磁気抵抗素子。 DESCRIPTION OF SYMBOLS 10 ... Magnetic field probe, 11 ... Sensor, 12 ... Board | substrate, 13 ... Permanent magnet, 14 ... Sensor fixed board | substrate, 15 ... Wiring, 16 ... Wiring edge part, 17 ... Gold wire, 18 ... Shielding film, 19-22 ... Anisotropic Magnetoresistive elements, 23a to 26a and 23b to 26b, anisotropic magnetoresistive elements.

Claims (3)

空間の磁界の強度と方向を検出する磁界プローブであって、異方性磁気抵抗素子が複数形成された基板と磁極面の中心から放射状に磁力線が放出される永久磁石とを具備したセンサと、導電率の高い素材で被われている配線部を備えた前記センサを固定するためのセンサ固定基板とからなり、
前記センサは、前記永久磁石の磁極面に平行な基板上に、前記永久磁石の磁極面の磁気的中心を原点としてＸ軸及びＹ軸上の原点から同一距離の位置に４つの領域を形成し、この各々の領域に対して、軸線と４５°（又は１３５°）の角度をなす方向に延伸した異方性磁気抵抗素子をそれぞれ形成して、合計４つの異方性磁気抵抗素子から構成されるようにし、前記４つの異方性磁気抵抗素子は、対角に位置する同士を結線してその間から出力をとるようにしたことを特徴とする磁界プローブ。 A magnetic field probe for detecting the intensity and direction of a magnetic field in space, comprising a substrate on which a plurality of anisotropic magnetoresistive elements are formed and a permanent magnet from which magnetic lines of force are emitted radially from the center of the magnetic pole surface ; It consists of a sensor fixing substrate for fixing the sensor having a wiring part covered with a material having high conductivity,
The sensor forms four regions on the substrate parallel to the magnetic pole surface of the permanent magnet, with the magnetic center of the magnetic pole surface of the permanent magnet as the origin and at the same distance from the origin on the X and Y axes. The anisotropic magnetoresistive element extended in a direction forming an angle of 45 ° (or 135 °) with the axis is formed for each of these regions, and is composed of a total of four anisotropic magnetoresistive elements. that as the said four anisotropic magnetoresistive element, a magnetic field characterized in that the mutually diagonally positioned to take the output from therebetween by connecting the probe. 空間の磁界の強度と方向を検出する磁界プローブであって、異方性磁気抵抗素子が複数形成された基板と磁極面の中心から放射状に磁力線が放出される永久磁石とを具備したセンサと、導電率の高い素材で被われている配線部を備えた前記センサを固定するためのセンサ固定基板とからなり、
前記センサは、前記永久磁石の磁極面に平行な基板上に、前記永久磁石の磁極面の磁気的中心を原点としてＸ軸及びＹ軸上の原点から同一距離の位置に４つの領域を形成し、この各々の領域に対して、互いの延伸する方向が成す角度が垂直でかつ軸線と４５°（又は１３５°）の角度をなす方向に延伸した２つの異方性磁気抵抗素子を隣接させて形成して、合計８つの異方性磁気抵抗素子から構成されることを特徴とする磁界プローブ。 A magnetic field probe for detecting the intensity and direction of a magnetic field in space, comprising a substrate on which a plurality of anisotropic magnetoresistive elements are formed and a permanent magnet from which magnetic lines of force are emitted radially from the center of the magnetic pole surface ; It consists of a sensor fixing substrate for fixing the sensor having a wiring part covered with a material having high conductivity,
The sensor forms four regions on the substrate parallel to the magnetic pole surface of the permanent magnet, with the magnetic center of the magnetic pole surface of the permanent magnet as the origin and at the same distance from the origin on the X and Y axes. Two anisotropic magnetoresistive elements extending in a direction in which the extending direction of each other is perpendicular to each of the regions and extending at an angle of 45 ° (or 135 °) with the axis are adjacent to each other. A magnetic field probe formed and composed of a total of eight anisotropic magnetoresistive elements. 前記異方性磁気抵抗素子が複数形成された基板は、低透磁率でかつ絶縁体であることを特徴とする請求項1又は２記載の磁界プローブ。   3. The magnetic field probe according to claim 1, wherein the substrate on which the plurality of anisotropic magnetoresistive elements are formed is an insulator with a low magnetic permeability.
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