JP4874781B2

JP4874781B2 - Magnetic sensor and magnetic encoder using the same

Info

Publication number: JP4874781B2
Application number: JP2006343031A
Authority: JP
Inventors: 孝二倉田; 一郎徳永; 拓哉清野
Original assignee: Alps Electric Co Ltd
Current assignee: Alps Alpine Co Ltd
Priority date: 2006-12-20
Filing date: 2006-12-20
Publication date: 2012-02-15
Anticipated expiration: 2026-12-20
Also published as: JP2008151759A

Description

本発明は、特に、出力波形の安定化を図ることができる等、検出精度を向上させることが可能な磁気センサ及びそれを用いた磁気エンコーダに関する。 In particular, the present invention relates to a magnetic sensor capable of improving detection accuracy, such as stabilization of an output waveform, and a magnetic encoder using the same.

巨大磁気抵抗効果（ＧＭＲ効果）を利用した磁気抵抗効果素子（ＧＭＲ素子）は、磁気エンコーダに使用できる。 A magnetoresistive effect element (GMR element) using the giant magnetoresistive effect (GMR effect) can be used for a magnetic encoder.

図１０は、従来における磁気エンコーダの部分断面図である。図１０に示す磁石１の表面は、磁気センサ２の相対移動方向に向けてＮ極とＳ極とが交互に配列された着磁面となっている。 FIG. 10 is a partial cross-sectional view of a conventional magnetic encoder. The surface of the magnet 1 shown in FIG. 10 is a magnetized surface in which N and S poles are alternately arranged in the relative movement direction of the magnetic sensor 2.

図１０に示すように、前記磁気センサ２は、基板３と前記基板３の表面に形成された磁気抵抗効果素子４，５とを有して構成される。 As shown in FIG. 10, the magnetic sensor 2 includes a substrate 3 and magnetoresistive elements 4 and 5 formed on the surface of the substrate 3.

前記磁気抵抗効果素子４，５は直列接続されている。前記磁石１のＮ極とＳ極間の中心幅（ピッチ）は、λ（図１１を参照）である。また直列接続された前記磁気抵抗効果素子４，５の中心間の間隔もλとなっている。前記磁気抵抗効果素子４，５は共に同じ積層体６で構成される。前記積層体６は下から反強磁性層７、固定磁性層８、非磁性材料層９、フリー磁性層１０及び保護層１１の順で積層される。 The magnetoresistive elements 4 and 5 are connected in series. The center width (pitch) between the N pole and the S pole of the magnet 1 is λ (see FIG. 11). The interval between the centers of the magnetoresistive elements 4 and 5 connected in series is also λ. The magnetoresistive elements 4 and 5 are composed of the same laminate 6. The laminate 6 is laminated in order of an antiferromagnetic layer 7, a pinned magnetic layer 8, a nonmagnetic material layer 9, a free magnetic layer 10 and a protective layer 11 from the bottom.

図１０に示すように、前記固定磁性層８は、前記反強磁性層７との間で生じる交換結合磁界（Ｈｅｘ）により図示Ｘ１方向に磁化固定されている。図１０には前記固定磁性層８の磁化方向が「ＰＩＮ」と表示されている。 As shown in FIG. 10, the pinned magnetic layer 8 is pinned in the X1 direction by an exchange coupling magnetic field (Hex) generated between the pinned magnetic layer 8 and the antiferromagnetic layer 7. In FIG. 10, the magnetization direction of the pinned magnetic layer 8 is displayed as “PIN”.

また前記フリー磁性層１０と前記固定磁性層８との間には層間結合磁界Ｈｉｎが生じており、前記フリー磁性層１０は前記層間結合磁界Ｈｉｎの方向に磁化されている。前記層間結合磁界Ｈｉｎは前記固定磁性層８の磁化方向と平行方向あるいは反平行方向のどちらかに生じる。図１０では前記層間結合磁界Ｈｉｎは前記固定磁性層８の磁化方向と平行な方向に生じている。 An interlayer coupling magnetic field Hin is generated between the free magnetic layer 10 and the pinned magnetic layer 8, and the free magnetic layer 10 is magnetized in the direction of the interlayer coupling magnetic field Hin. The interlayer coupling magnetic field Hin is generated either in the direction parallel to the magnetization direction of the pinned magnetic layer 8 or in the antiparallel direction. In FIG. 10, the interlayer coupling magnetic field Hin is generated in a direction parallel to the magnetization direction of the pinned magnetic layer 8.

図１０に示すように、前記磁気抵抗効果素子４，５が、夫々、磁石１のＮ極とＳ極との境界部の真下に位置すると、前記磁気抵抗効果素子４には、前記磁石１から図示Ｘ２方向に向う外部磁界Ｈ１が支配的に流入し、前記磁気抵抗効果素子５には、前記磁石１から図示Ｘ１方向に向う外部磁界Ｈ２が支配的に流入する。 As shown in FIG. 10, when the magnetoresistive effect elements 4 and 5 are respectively located directly below the boundary between the north pole and the south pole of the magnet 1, the magnetoresistive effect element 4 includes the magnet 1 from the magnet 1. An external magnetic field H1 directed in the X2 direction in the figure flows dominantly, and an external magnetic field H2 in the X1 direction in the figure from the magnet 1 dominantly flows into the magnetoresistive effect element 5.

前記磁気センサ２が前記磁石１に対し図示Ｘ１方向に向けて相対移動すると、前記磁気抵抗効果素子４，５に流入する外部磁界Ｈの方向が変化することで、各磁気抵抗効果素子４，５の電気抵抗値が変化する。前記電気抵抗値の変化に基づく電圧変化は、略矩形状の出力波形として得られ、前記出力波形により、前記磁石１の移動速度や移動距離等を知ることが可能となっている。
特開２００３−６０２５６号公報 When the magnetic sensor 2 moves relative to the magnet 1 in the X1 direction in the figure, the direction of the external magnetic field H flowing into the magnetoresistive elements 4 and 5 changes, so that each of the magnetoresistive elements 4 and 5 The electrical resistance value changes. The voltage change based on the change in the electric resistance value is obtained as a substantially rectangular output waveform, and it is possible to know the moving speed and moving distance of the magnet 1 from the output waveform.
JP 2003-60256 A

しかしながら、前記フリー磁性層１０には、前記固定磁性層８の磁化方向（ＰＩＮ方向）と同じ方向である図示Ｘ１方向に層間結合磁界Ｈｉｎが生じているので、図示Ｘ１方向に外部磁界Ｈ２が作用しても、図１０に示す前記磁気抵抗効果素子５の電気抵抗値は変化しない。 However, an interlayer coupling magnetic field Hin is generated in the free magnetic layer 10 in the X1 direction, which is the same direction as the magnetization direction (PIN direction) of the pinned magnetic layer 8, so that an external magnetic field H2 acts in the X1 direction. Even so, the electrical resistance value of the magnetoresistive element 5 shown in FIG. 10 does not change.

すなわち前記磁気抵抗効果素子４，５を構成するフリー磁性層１０は、外部磁界Ｈの方向によって向きやすさ（感度）が異なっている。よって図１０に示す従来構成では、検出精度を適切に向上させることが出来なかった。 That is, the easiness (sensitivity) of the free magnetic layer 10 constituting the magnetoresistive effect elements 4 and 5 differs depending on the direction of the external magnetic field H. Therefore, in the conventional configuration shown in FIG. 10, the detection accuracy cannot be improved appropriately.

一方、図１１に示すように、磁気抵抗効果素子４，５の固定磁性層８の磁化方向（ＰＩＮ方向）を図示Ｘ１方向に固定しておき、前記固定磁性層８とフリー磁性層１０との間に生じる層間結合磁界Ｈｉｎをゼロになるように調整する構成も考えられる。前記層間結合磁界Ｈｉｎは、例えば、前記固定磁性層８と前記フリー磁性層１０との間に設けられる非磁性材料層９の膜厚によって調整できる。 On the other hand, as shown in FIG. 11, the magnetization direction (PIN direction) of the pinned magnetic layer 8 of the magnetoresistive effect elements 4 and 5 is pinned in the X1 direction, and the pinned magnetic layer 8 and the free magnetic layer 10 are A configuration is also conceivable in which the interlayer coupling magnetic field Hin generated therebetween is adjusted to zero. The interlayer coupling magnetic field Hin can be adjusted by, for example, the film thickness of the nonmagnetic material layer 9 provided between the pinned magnetic layer 8 and the free magnetic layer 10.

図１２は、図１１に示す層間結合磁界Ｈｉｎをゼロに調整した磁気抵抗効果素子４，５のＲ−Ｈ曲線１２を示している。 FIG. 12 shows an RH curve 12 of the magnetoresistive effect elements 4 and 5 in which the interlayer coupling magnetic field Hin shown in FIG. 11 is adjusted to zero.

図１２に示すようにＲ−Ｈ曲線１２のループ部１３は横軸方向（外部磁界Ｈ方向）に所定幅を有しており、この所定幅がヒステリシスである。 As shown in FIG. 12, the loop portion 13 of the RH curve 12 has a predetermined width in the horizontal axis direction (external magnetic field H direction), and this predetermined width is hysteresis.

図１１に示すように、磁気抵抗効果素子４，５の真上に磁石１の各磁極中心が位置したとき、前記磁気抵抗効果素子４，５には膜面と垂直方向（図示Ｚ１方向、あるいは図示Ｚ２方向）から外部磁界Ｈ３，Ｈ４が作用する。 As shown in FIG. 11, when each magnetic pole center of the magnet 1 is positioned directly above the magnetoresistive effect elements 4 and 5, the magnetoresistive effect elements 4 and 5 have a direction perpendicular to the film surface (Z1 direction shown in FIG. External magnetic fields H3 and H4 act from the Z2 direction in the figure.

前記磁気抵抗効果素子４，５のフリー磁性層１０は前記外部磁界Ｈ３，H４に対して磁化変動しない。すなわち前記磁気抵抗効果素子４，５に外部磁界Ｈが作用していない無磁場状態と同じ状態となる。 The free magnetic layer 10 of the magnetoresistive elements 4 and 5 does not fluctuate with respect to the external magnetic fields H3 and H4. That is, the magnetoresistive effect elements 4 and 5 are in the same state as the no magnetic field state in which the external magnetic field H is not acting.

無磁場状態における磁気抵抗効果素子４，５の電気抵抗値を、図１２に示すＲ−Ｈグラフで見ると、磁気抵抗効果素子４，５の電気抵抗値はＲ１かＲ２となっている。すなわち、無磁場状態では、磁気抵抗効果素子４，５の電気抵抗値は一定にならず、不安定となっている。 When the electric resistance values of the magnetoresistive effect elements 4 and 5 in the non-magnetic field state are viewed in the RH graph shown in FIG. 12, the electric resistance values of the magnetoresistive effect elements 4 and 5 are R1 or R2. That is, in the absence of a magnetic field, the electric resistance values of the magnetoresistive elements 4 and 5 are not constant and are unstable.

そして層間結合磁界Ｈｉｎがゼロに調整された磁気抵抗効果素子４，５を有する磁気センサ２の出力波形を調べると、平滑でなく乱れが生じており（波打っており）、出力波形が不安定となることがわかった。 When the output waveform of the magnetic sensor 2 having the magnetoresistive elements 4 and 5 in which the interlayer coupling magnetic field Hin is adjusted to zero is examined, the output waveform is not smooth but turbulent (wavy), and the output waveform is unstable. I found out that

特許文献１に記載された発明では、磁気エンコーダの上記した問題点について何ら言及していない。加えて、特許文献１では、特許文献１の図６に示すように、フリー磁性層の磁化方向と固定磁性層の磁化方向とが平行あるいは反平行であり、図１０で指摘した磁化方向と同じである。 The invention described in Patent Document 1 makes no mention of the above-described problems of the magnetic encoder. In addition, in Patent Document 1, as shown in FIG. 6 of Patent Document 1, the magnetization direction of the free magnetic layer and the magnetization direction of the pinned magnetic layer are parallel or antiparallel, which is the same as the magnetization direction pointed out in FIG. It is.

そこで本発明は上記従来の課題を解決するためのものであり、特に、簡単な構成で、出力波形の安定化を図ることができる等、検出精度を向上させることが可能な磁気センサ及びそれを用いた磁気エンコーダを提供することを目的としている。 Therefore, the present invention is for solving the above-described conventional problems, and in particular, a magnetic sensor capable of improving detection accuracy, such as being capable of stabilizing the output waveform with a simple configuration, and the like. It aims at providing the used magnetic encoder.

本発明は、基板上に、磁界発生部材からの外部磁界に対して電気抵抗値が変化する磁気抵抗効果を利用した磁気抵抗効果素子を有する磁気センサであって、
前記磁気抵抗効果素子は複数個、前記基板上に設けられるとともに、磁化が一方向に固定された固定磁性層と、前記外部磁界に対して磁化変動するフリー磁性層とが、非磁性材料層を介して積層された積層部分を有し、
全ての前記磁気抵抗効果素子における前記固定磁性層の磁化方向は平行であるか、あるいは少なくとも一つの前記磁気抵抗効果素子における前記固定磁性層の磁化方向が、残りの前記磁気抵抗効果素子における前記固定磁性層の磁化方向に対して反平行であり、
前記磁気抵抗効果素子と離れた位置に永久磁石が設けられ、前記磁界発生部材からの外部磁界が作用しない無磁場状態において、全ての前記磁気抵抗効果素子の前記フリー磁性層が、前記永久磁石からの同じバイアス磁界によって、前記固定磁性層の磁化方向と直交方向で且つ前記バイアス磁界の作用方向と同一方向に、磁化されていることを特徴とするものである。 The present invention is a magnetic sensor having a magnetoresistive effect element utilizing a magnetoresistive effect in which an electric resistance value changes with respect to an external magnetic field from a magnetic field generating member on a substrate,
A plurality of the magnetoresistive effect elements are provided on the substrate, and a fixed magnetic layer whose magnetization is fixed in one direction and a free magnetic layer whose magnetization is fluctuated with respect to the external magnetic field are a nonmagnetic material layer. Having a laminated portion laminated through,
The magnetization direction of the pinned magnetic layer in all the magnetoresistive effect elements is parallel, or the magnetization direction of the pinned magnetic layer in at least one of the magnetoresistive effect elements is the pinned in the remaining magnetoresistive effect elements. Antiparallel to the magnetization direction of the magnetic layer,
A permanent magnet is provided at a position away from the magnetoresistive effect element, and the free magnetic layer of all the magnetoresistive effect elements is separated from the permanent magnet in a no-magnetic field state where an external magnetic field from the magnetic field generating member does not act. Are magnetized in the direction perpendicular to the magnetization direction of the pinned magnetic layer and in the same direction as the action direction of the bias magnetic field .

本発明では、各磁気抵抗効果素子のフリー磁性層の磁化方向を前記固定磁性層の固定磁化方向に対して直交する方向に向けている。特に、永久磁石を用いて、全ての前記磁気抵抗効果素子の前記フリー磁性層を、前記永久磁石からの同じバイアス磁界によって同一方向に向けているので、簡単な構成で、前記フリー磁性層の磁化調整を行うことが可能である。 In the present invention, the magnetization direction of the free magnetic layer of each magnetoresistive effect element is oriented in a direction orthogonal to the fixed magnetization direction of the fixed magnetic layer. In particular, since the free magnetic layers of all the magnetoresistive effect elements are directed in the same direction by the same bias magnetic field from the permanent magnets using permanent magnets, the magnetization of the free magnetic layers can be performed with a simple configuration. Adjustments can be made.

このように全ての磁気抵抗効果素子のフリー磁性層の磁化を固定磁性層の固定磁化方向に対して直交させることで、出力波形の乱れを従来に比べて改善でき、また外部磁界の作用方向に対する磁気感度の違いを改善でき、したがって従来に比べて検出精度を向上できる。 Thus, by making the magnetization of the free magnetic layer of all the magnetoresistive effect elements orthogonal to the fixed magnetization direction of the fixed magnetic layer, the disturbance of the output waveform can be improved as compared with the conventional one, and the direction of the external magnetic field is affected. The difference in magnetic sensitivity can be improved, and therefore the detection accuracy can be improved as compared with the conventional case.

本発明では、前記基板の表面に前記磁気抵抗効果素子が設けられ、前記基板の裏面に前記永久磁石が設けられることが好ましい。これにより磁気センサの構成を簡単に出来る。 In this invention, it is preferable that the said magnetoresistive effect element is provided in the surface of the said board | substrate, and the said permanent magnet is provided in the back surface of the said board | substrate. Thereby, the configuration of the magnetic sensor can be simplified.

また本発明では、前記磁気抵抗効果素子は、幅方向の寸法よりも前記幅方向と直交する長さ方向の寸法のほうが長く形成された形状であり、前記固定磁性層が、前記幅方向に磁化固定され、フリー磁性層が前記長さ方向に磁化されている構成に特に好ましく適用できる。 In the present invention, the magnetoresistive element has a shape in which the dimension in the length direction perpendicular to the width direction is longer than the dimension in the width direction, and the pinned magnetic layer is magnetized in the width direction. The present invention can be particularly preferably applied to a configuration in which the fixed and free magnetic layer is magnetized in the length direction.

また本発明は、表面に、Ｎ極とＳ極が交互に着磁された着磁面を有する磁界発生部材と、上記のいずれかに記載された磁気センサとを備える磁気エンコーダであって、
前記Ｎ極及びＳ極は、前記磁気センサの相対移動方向あるいは相対回転方向に交互に配列されて、前記磁気センサには、相対移動あるいは相対回転に伴って、前記相対移動方向あるいは前記相対回転方向に向う（＋）方向への外部磁界と、前記（＋）方向とは逆方向の（−）方向への外部磁界とが交互に作用し、
直列接続される磁気抵抗効果素子どうしは、前記相対移動方向と平行な方向に、あるいは、前記基板の中心を相対回転方向上の接点としたときの接線方向と平行な方向に、ずれて配置され、
各磁気抵抗効果素子の固定磁性層が、夫々、前記相対移動方向と平行あるいは反平行な方向に、あるいは、前記接線方向と平行あるいは反平行な方向に磁化固定されていることを特徴とするものである。 Further, the present invention is a magnetic encoder comprising a magnetic field generating member having a magnetized surface in which N and S poles are alternately magnetized on the surface, and the magnetic sensor described in any of the above,
The N pole and the S pole are alternately arranged in the relative movement direction or the relative rotation direction of the magnetic sensor, and the relative movement direction or the relative rotation direction is provided to the magnetic sensor in accordance with the relative movement or the relative rotation. The external magnetic field in the (+) direction toward the direction and the external magnetic field in the (−) direction opposite to the (+) direction act alternately,
The magnetoresistive effect elements connected in series are displaced in a direction parallel to the relative movement direction or in a direction parallel to a tangential direction when the center of the substrate is a contact point in the relative rotation direction. ,
The pinned magnetic layer of each magnetoresistive element is fixed in magnetization in a direction parallel or antiparallel to the relative movement direction, or in a direction parallel or antiparallel to the tangential direction, respectively. It is.

本発明の磁気センサは、上記したように磁気エンコーダに好ましく適用できる。これにより出力波形の安定化を図ることができ、移動速度や移動距離を適切に検出することが出来る。 As described above, the magnetic sensor of the present invention can be preferably applied to a magnetic encoder. As a result, the output waveform can be stabilized, and the moving speed and moving distance can be detected appropriately.

本発明では、前記Ｎ極と前記Ｓ極の中心間距離をλとしたとき、直列接続される磁気抵抗効果素子どうしは、前記相対移動方向と平行な方向に、あるいは、前記接線方向と平行な方向に、λの中心間距離を空けて配置されており、
全ての磁気抵抗効果素子の前記固定磁性層が、同一方向に磁化固定されている構成に特に好ましく適用できる。 In the present invention, when the distance between the centers of the N pole and the S pole is λ, magnetoresistive elements connected in series are parallel to the relative movement direction or parallel to the tangential direction. In the direction, with a distance between the centers of λ,
The present invention can be particularly preferably applied to a configuration in which the pinned magnetic layers of all the magnetoresistive elements are fixed in magnetization in the same direction.

本発明における磁気センサ及びそれを用いた磁気エンコーダでは、簡単な構成で、出力波形の安定化を図ることができる等、検出精度を向上させることが可能である。 In the magnetic sensor and the magnetic encoder using the same according to the present invention, the detection accuracy can be improved, for example, the output waveform can be stabilized with a simple configuration.

図１は本実施形態の磁気エンコーダの部分斜視図、図２は、磁気センサの部分拡大平面図、図３は図２に示すＡ−Ａ線から膜厚方向に切断し矢印方向から見た前記磁気エンコーダの部分拡大断面図、図４は、図３の状態から磁気センサが、λ／２だけ相対移動したときの前記磁気エンコーダの部分拡大断面図、図５は、図２に示すＢ−Ｂ線から膜厚方向に切断し矢印方向から見た前記磁気センサの拡大断面図、図６は、図５の変形例を示す磁気センサの断面図、図７は、磁気センサの回路図、図８は磁気抵抗効果素子のＨ／／ＰＩＮ方向のＲ−Ｈ曲線を示すグラフ、である。 FIG. 1 is a partial perspective view of the magnetic encoder of the present embodiment, FIG. 2 is a partially enlarged plan view of the magnetic sensor, and FIG. 3 is a view cut in the film thickness direction from the line AA shown in FIG. 4 is a partially enlarged sectional view of the magnetic encoder, FIG. 4 is a partially enlarged sectional view of the magnetic encoder when the magnetic sensor is relatively moved from the state of FIG. 3 by λ / 2, and FIG. 5 is a BB shown in FIG. FIG. 6 is a cross-sectional view of the magnetic sensor showing a modification of FIG. 5, and FIG. 7 is a circuit diagram of the magnetic sensor. These are the graphs which show the RH curve of the H // PIN direction of a magnetoresistive effect element.

各図におけるＸ１−Ｘ２方向、Ｙ１−Ｙ２方向、及びＺ１−Ｚ２方向の各方向は残り２つの方向に対して直交した関係となっている。Ｘ１方向は、磁石あるいは磁気センサの移動方向である。Ｚ１−Ｚ２方向は前記磁石と磁気センサとが所定の間隔を空けて対向する方向である。 Each direction of the X1-X2 direction, the Y1-Y2 direction, and the Z1-Z2 direction in each figure has a relationship orthogonal to the remaining two directions. The X1 direction is a moving direction of the magnet or the magnetic sensor. The Z1-Z2 direction is a direction in which the magnet and the magnetic sensor face each other with a predetermined interval.

図１に示すように磁気エンコーダ２０は、第１の永久磁石２１と磁気センサ２２を有して構成される。 As shown in FIG. 1, the magnetic encoder 20 includes a first permanent magnet 21 and a magnetic sensor 22.

前記第１の永久磁石（磁界発生部材）２１は図示Ｘ１−Ｘ２方向に延びる棒形状であり、図示Ｘ１−Ｘ２方向に所定幅にてＮ極とＳ極とが交互に着磁されている。Ｎ極の着磁面と、隣接するＳ極の着磁面との間の中心幅（ピッチ）はλである。 The first permanent magnet (magnetic field generating member) 21 has a rod shape extending in the X1-X2 direction in the figure, and N poles and S poles are alternately magnetized with a predetermined width in the X1-X2 direction in the figure. The center width (pitch) between the N pole magnetized surface and the adjacent S pole magnetized surface is λ.

図１に示すように前記第１の永久磁石２１と前記磁気センサ２２との間には所定の間隔Ｓ１が空けられている。 As shown in FIG. 1, a predetermined interval S <b> 1 is provided between the first permanent magnet 21 and the magnetic sensor 22.

図１に示すように前記磁気センサ２２は、基板２３と、同一の前記基板２３の表面（第１の永久磁石２１との対向面）２３ａに設けられた複数の磁気抵抗効果素子２４ａ〜２４ｈと、前記基板２３の裏面２３ｂに設けられた１個の第２の永久磁石２５とを有して構成される。 As shown in FIG. 1, the magnetic sensor 22 includes a substrate 23 and a plurality of magnetoresistive elements 24 a to 24 h provided on the same surface 23 a (a surface facing the first permanent magnet 21) 23 a of the same substrate 23. And a second permanent magnet 25 provided on the back surface 23b of the substrate 23.

図１及び図２に示すように、８個の磁気抵抗効果素子２４ａ〜２４ｈは、Ｘ１−Ｘ２方向に４個ずつ、Ｙ１−Ｙ２方向に２個ずつマトリクス状に配列している。図２に示すようにＸ１−Ｘ２方向にて隣り合う各磁気抵抗効果素子の幅方向（図示Ｘ１−Ｘ２方向）の中心間の間隔はλ／２となっている。 As shown in FIG. 1 and FIG. 2, the eight magnetoresistive elements 24a to 24h are arranged in a matrix form, four in the X1-X2 direction and two in the Y1-Y2 direction. As shown in FIG. 2, the distance between the centers in the width direction (X1-X2 direction in the drawing) of each magnetoresistive element adjacent in the X1-X2 direction is λ / 2.

図３に示すように各磁気抵抗効果素子２４ａ〜２４ｈは全て同じ積層体３５で構成される。図３には、磁気抵抗効果素子２４ａ〜２４ｃのみが図示されているが、磁気抵抗効果素子２４ｄ〜２４ｈも同じ積層体で形成される。このように全ての磁気抵抗効果素子２４ａ〜２４ｈが同じ積層体３５で形成されるので、これら磁気抵抗効果素子２４ａ〜２４ｈを全て同じ製造工程で形成でき、しかも後述するように各磁気抵抗効果素子２４ａ〜２４ｈの磁化方向も同じであるので、容易に製造できる。 As shown in FIG. 3, each of the magnetoresistive effect elements 24 a to 24 h is composed of the same stacked body 35. Although only the magnetoresistive effect elements 24a to 24c are illustrated in FIG. 3, the magnetoresistive effect elements 24d to 24h are also formed of the same laminate. Thus, since all the magnetoresistive effect elements 24a-24h are formed by the same laminated body 35, these magnetoresistive effect elements 24a-24h can be formed in the same manufacturing process, and each magnetoresistive effect element is described later. Since the magnetization direction of 24a-24h is also the same, it can manufacture easily.

図３に示すように磁気抵抗効果素子は、下から反強磁性層３０、固定磁性層３１、非磁性材料層３２、フリー磁性層３３及び保護層３４の順で積層された積層体３５で形成される。前記積層体３５は前記反強磁性層３０と前記基板２３との間に下地層が形成されたり、積層体３５の膜構成は図３に限定されない。また、前記積層体３５は下からフリー磁性層３３、非磁性材料層３２、固定磁性層３１、反強磁性層３０及び保護層３４の順に積層されてもよい。 As shown in FIG. 3, the magnetoresistive effect element is formed by a laminated body 35 in which an antiferromagnetic layer 30, a pinned magnetic layer 31, a nonmagnetic material layer 32, a free magnetic layer 33 and a protective layer 34 are laminated in this order from the bottom. Is done. In the laminated body 35, an underlayer is formed between the antiferromagnetic layer 30 and the substrate 23, and the film configuration of the laminated body 35 is not limited to FIG. 3. The laminated body 35 may be laminated in order of the free magnetic layer 33, the nonmagnetic material layer 32, the pinned magnetic layer 31, the antiferromagnetic layer 30, and the protective layer 34 from the bottom.

前記反強磁性層３０は例えばＰｔＭｎやＩｒＭｎで形成される。前記固定磁性層３１及びフリー磁性層３３は例えば、ＮｉＦｅやＣｏＦｅで形成される。前記非磁性材料層３２は例えばＣｕで形成される。また前記保護層３４は例えばＴａで形成される。 The antiferromagnetic layer 30 is made of, for example, PtMn or IrMn. The pinned magnetic layer 31 and the free magnetic layer 33 are made of, for example, NiFe or CoFe. The nonmagnetic material layer 32 is made of Cu, for example. The protective layer 34 is made of Ta, for example.

前記反強磁性層３０と前記固定磁性層３１との間には交換結合磁界（Ｈｅｘ）が生じて前記固定磁性層３１の磁化は一方向に固定されている。図２，図３に示すように全ての磁気抵抗効果素子２４ａ〜２４ｈの固定磁性層３１の磁化方向（ＰＩＮ方向）は図示Ｘ１方向（相対移動方向）に固定されている。一方、前記フリー磁性層３３の磁化方向は固定されておらず外部磁界（センシング磁界）によって磁化変動する。なお、前記固定磁性層３１の磁化方向は図示Ｘ２方向（相対移動方向に対して反平行）でもよい。 An exchange coupling magnetic field (Hex) is generated between the antiferromagnetic layer 30 and the pinned magnetic layer 31, and the magnetization of the pinned magnetic layer 31 is pinned in one direction. As shown in FIGS. 2 and 3, the magnetization direction (PIN direction) of the pinned magnetic layer 31 of all the magnetoresistive elements 24a to 24h is fixed in the X1 direction (relative movement direction). On the other hand, the magnetization direction of the free magnetic layer 33 is not fixed and fluctuates due to an external magnetic field (sensing magnetic field). The magnetization direction of the pinned magnetic layer 31 may be the X2 direction (antiparallel to the relative movement direction).

なお本実施形態では、前記非磁性材料層３２が非磁性導電材料で形成された巨大磁気抵抗効果（ＧＭＲ効果）を利用したＧＭＲ素子に代えて、前記非磁性材料層３２がＡｌ_２Ｏ_３等の絶縁材料で形成されたトンネル型磁気抵抗効果素子（ＴＭＲ素子）を用いてもよい。 In this embodiment, instead of the GMR element using the giant magnetoresistance effect (GMR effect) in which the nonmagnetic material layer 32 is formed of a nonmagnetic conductive material, the nonmagnetic material layer 32 is made of Al ₂ O ₃ or the like. Alternatively, a tunnel type magnetoresistive element (TMR element) formed of any insulating material may be used.

本実施形態では、全ての磁気抵抗効果素子２４ａ〜２４ｈのフリー磁性層３３には、図３，図５に示すように、前記基板２３の裏面２３ｂに設けられた第２の磁石２５から生じたバイアス磁界ｂｉａｓが印加されている。これにより全ての磁気抵抗効果素子２４ａ〜２４ｈの前記フリー磁性層３３の磁化方向３３ａは、図２，図５に示すように、図示Ｙ１方向に向けられている。 In the present embodiment, the free magnetic layers 33 of all the magnetoresistive elements 24a to 24h are generated from the second magnet 25 provided on the back surface 23b of the substrate 23 as shown in FIGS. A bias magnetic field bias is applied. Thereby, the magnetization direction 33a of the free magnetic layer 33 of all the magnetoresistive effect elements 24a to 24h is oriented in the Y1 direction as shown in FIGS.

図２に示すように、前記フリー磁性層３３の磁化方向３３ａと固定磁性層３１の磁化方向（ＰＩＮ方向）とは直交した関係にある。図８が各磁気抵抗効果素子２４ａ〜２４ｈのＲ−Ｈ曲線４０である。図１２に示す従来の磁気抵抗効果素子のように、ヒステリシスが生じておらず、直線状のＲ−Ｈ曲線４０を形成している。 As shown in FIG. 2, the magnetization direction 33a of the free magnetic layer 33 and the magnetization direction (PIN direction) of the pinned magnetic layer 31 are orthogonal to each other. FIG. 8 is an RH curve 40 of each of the magnetoresistive effect elements 24a to 24h. Unlike the conventional magnetoresistive effect element shown in FIG. 12, there is no hysteresis, and a linear RH curve 40 is formed.

次に以下では、磁気抵抗効果素子２４ａを第１の磁気抵抗効果素子２４ａ、磁気抵抗効果素子２４ｂを第２の磁気抵抗効果素子２４ｂ、磁気抵抗効果素子２４ｃを第３の磁気抵抗効果素子２４ｃ、磁気抵抗効果素子２４ｄを第４の磁気抵抗効果素子２４ｄ、磁気抵抗効果素子２４ｅを第５の磁気抵抗効果素子２４ｅ、磁気抵抗効果素子２４ｆを第６の磁気抵抗効果素子２４ｆ、磁気抵抗効果素子２４ｇを第７の磁気抵抗効果素子２４ｇ、磁気抵抗効果素子２４ｈを第８の磁気抵抗効果素子２４ｈと称することとする。 Next, in the following, the magnetoresistive effect element 24a is the first magnetoresistive effect element 24a, the magnetoresistive effect element 24b is the second magnetoresistive effect element 24b, the magnetoresistive effect element 24c is the third magnetoresistive effect element 24c, The magnetoresistive effect element 24d is the fourth magnetoresistive effect element 24d, the magnetoresistive effect element 24e is the fifth magnetoresistive effect element 24e, the magnetoresistive effect element 24f is the sixth magnetoresistive effect element 24f, and the magnetoresistive effect element 24g. Is referred to as a seventh magnetoresistive element 24g, and the magnetoresistive element 24h is referred to as an eighth magnetoresistive element 24h.

図７に示すように、第１の磁気抵抗効果素子２４ａ、第３の磁気抵抗効果素子２４ｃ、第５の磁気抵抗効果素子２４ｅ及び第７の磁気抵抗効果素子２４ｇによりＡ相のブリッジ回路が構成されている。第１の磁気抵抗効果素子２４ａと第３の磁気抵抗効果素子２４ｃとが第１の出力取り出し部５０を介して直列接続され、第５の磁気抵抗効果素子２４ｅと第７の磁気抵抗効果素子２４ｇとが第２の出力取り出し部５１を介して直列接続されている。また、図７に示すように第１の磁気抵抗効果素子２４ａと第７の磁気抵抗効果素子２４ｇとが入力端子５２を介して並列接続され、前記第３の磁気抵抗効果素子２４ｃと前記第５の磁気抵抗効果素子２４ｅとがアース端子５３を介して並列接続されている。 As shown in FIG. 7, the first magnetoresistive element 24a, the third magnetoresistive element 24c, the fifth magnetoresistive element 24e, and the seventh magnetoresistive element 24g constitute an A-phase bridge circuit. Has been. The first magnetoresistive effect element 24a and the third magnetoresistive effect element 24c are connected in series via the first output extraction section 50, and the fifth magnetoresistive effect element 24e and the seventh magnetoresistive effect element 24g are connected. Are connected in series via the second output extraction portion 51. Further, as shown in FIG. 7, the first magnetoresistive effect element 24a and the seventh magnetoresistive effect element 24g are connected in parallel via the input terminal 52, and the third magnetoresistive effect element 24c and the fifth magnetoresistive effect element 24c are connected to each other. Are connected in parallel via a ground terminal 53.

図７に示すように第１の出力取り出し部５０と第２の出力取り出し部５１は、第１の差動増幅器５８の入力部側に接続され、前記第１の差動増幅器５８の出力側が第１の出力端子５９に接続されている。 As shown in FIG. 7, the first output extraction section 50 and the second output extraction section 51 are connected to the input section side of the first differential amplifier 58, and the output side of the first differential amplifier 58 is the first output section. 1 output terminal 59.

また本実施形態ではもう一つＢ相のブリッジ回路が、第２の磁気抵抗効果素子２４ｂ、第４の磁気抵抗効果素子２４ｄ、第６の磁気抵抗効果素子２４ｆ及び第８の磁気抵抗効果素子２４ｈにより構成されている。第２の磁気抵抗効果素子２４ｂと第４の磁気抵抗効果素子２４ｄとが第３の出力取り出し部５４を介して直列接続され、第６の磁気抵抗効果素子２４ｆと第８の磁気抵抗効果素子２４ｈとが第４の出力取り出し部５５を介して直列接続されている。また、図７に示すように第２の磁気抵抗効果素子２４ｂと第８の磁気抵抗効果素子２４ｈとが入力端子５６を介して並列接続され、前記第４の磁気抵抗効果素子２４ｄと前記第６の磁気抵抗効果素子２４ｆとがアース端子５７を介して並列接続されている。 In the present embodiment, another B-phase bridge circuit includes the second magnetoresistive element 24b, the fourth magnetoresistive element 24d, the sixth magnetoresistive element 24f, and the eighth magnetoresistive element 24h. It is comprised by. The second magnetoresistive effect element 24b and the fourth magnetoresistive effect element 24d are connected in series via the third output extraction portion 54, and the sixth magnetoresistive effect element 24f and the eighth magnetoresistive effect element 24h. Are connected in series via the fourth output extraction portion 55. Further, as shown in FIG. 7, the second magnetoresistive effect element 24b and the eighth magnetoresistive effect element 24h are connected in parallel via the input terminal 56, and the fourth magnetoresistive effect element 24d and the sixth magnetoresistive effect element 24d are connected to each other. The magnetoresistive effect element 24 f is connected in parallel via a ground terminal 57.

図７に示すように第３の出力取り出し部５４と第４の出力取り出し部５５は、第２の差動増幅器６０の入力部側に接続され、前記第２の差動増幅器６０の出力側が第２の出力端子６１に接続されている。 As shown in FIG. 7, the third output extraction section 54 and the fourth output extraction section 55 are connected to the input section side of the second differential amplifier 60, and the output side of the second differential amplifier 60 is the first output section. 2 output terminals 61.

図２に示すように、図７に示すブリッジ回路にて直列接続される磁気抵抗効果素子どうしの中心間の間隔はλとなっている。 As shown in FIG. 2, the distance between the centers of the magnetoresistive elements connected in series in the bridge circuit shown in FIG. 7 is λ.

本実施形態では、磁気センサ２２あるいは第１の永久磁石２１のどちらか一方が図示Ｘ１―図示Ｘ２方向と平行な方向に直線移動可能に支持されている。本実施形態では前記磁気センサ２２の相対移動空間内に、前記第１の永久磁石２１から生じる外部磁界領域が形成されている。ここで相対移動方向（図１では図示Ｘ１方向）を（＋）方向と、相対移動方向と逆方向（図１では図示Ｘ２方向）を（−）方向と定めると、図１に示すように、前記外部磁界領域では、前記相対移動方向に向う（＋）方向への外部磁界Ｈ５と、前記相対移動方向とは逆方向に向う（−）方向への外部磁界Ｈ６とが交互に発生している。 In the present embodiment, either the magnetic sensor 22 or the first permanent magnet 21 is supported so as to be linearly movable in a direction parallel to the illustrated X1-X2 direction. In the present embodiment, an external magnetic field region generated from the first permanent magnet 21 is formed in the relative movement space of the magnetic sensor 22. Here, when the relative movement direction (X1 direction in FIG. 1) is defined as the (+) direction and the opposite direction (X2 direction in FIG. 1) is defined as the (−) direction, as shown in FIG. In the external magnetic field region, an external magnetic field H5 in the (+) direction toward the relative movement direction and an external magnetic field H6 in the (−) direction opposite to the relative movement direction are alternately generated. .

図３に示すように、ちょうど、第１の磁気抵抗効果素子２４ａの頭上に、第１の永久磁石２１のＮ極の中心が対向した位置関係になると、前記第１の磁気抵抗効果素子２４ａのフリー磁性層３３には、前記（＋）方向及び（−）方向の外部磁界Ｈ５，Ｈ６のベクトル成分のうち、図示Ｚ１方向（紙面下方向）へのベクトル成分の外部磁界Ｈ７が支配的に流入する。前記外部磁界Ｈ７は、第１の磁気抵抗効果素子２４ａの膜面（Ｘ−Ｙ面と平行な面）に対して垂直方向であるため、前記フリー磁性層３３の磁化方向３３ａは変動せず、前記固定磁性層３１の磁化方向（ＰＩＮ方向）と直交した関係を維持する。よって前記第１の磁気抵抗効果素子２４ａには外部磁界Ｈが作用していない無磁場状態と同じ状態が作用し、前記第１の磁気抵抗効果素子２４ａの電気抵抗値は変動しない。 As shown in FIG. 3, when the center of the N pole of the first permanent magnet 21 faces just above the head of the first magnetoresistive element 24a, the first magnetoresistive element 24a Out of the vector components of the external magnetic fields H5 and H6 in the (+) direction and the (−) direction, the external magnetic field H7 of the vector component in the Z1 direction (downward direction in the drawing) dominantly flows into the free magnetic layer 33. To do. Since the external magnetic field H7 is perpendicular to the film surface of the first magnetoresistive element 24a (a surface parallel to the XY plane), the magnetization direction 33a of the free magnetic layer 33 does not vary, The relationship orthogonal to the magnetization direction (PIN direction) of the pinned magnetic layer 31 is maintained. Therefore, the same state as the non-magnetic field state where the external magnetic field H is not acting acts on the first magnetoresistive effect element 24a, and the electric resistance value of the first magnetoresistive effect element 24a does not fluctuate.

また、前記第１の磁気抵抗効果素子２４ａと直列接続され、前記第１の磁気抵抗効果素子２４ａとλの中心間距離を空けた第３の磁気抵抗効果素子２４ｃの頭上には、第１の永久磁石２１のＳ極の中心が対向した位置関係になる。このとき、前記第３の磁気抵抗効果素子２４ｃのフリー磁性層３３には、前記（＋）方向及び（−）方向の外部磁界Ｈ５，Ｈ６のベクトル成分のうち、図示Ｚ２方向（紙面上方向）へのベクトル成分の外部磁界Ｈ８が支配的に流入する。前記外部磁界Ｈ８は、第３の磁気抵抗効果素子２４ｃの膜面（Ｘ−Ｙ面と平行な面）に対して垂直方向であるため、前記フリー磁性層３３の磁化方向３３ａは変動せず、前記固定磁性層３１の磁化方向（ＰＩＮ方向）と直交した関係を維持する。よって前記第３の磁気抵抗効果素子２４ｃには外部磁界Ｈが作用していない無磁場状態と同じ状態が作用し、前記第３の磁気抵抗効果素子２４ｃの電気抵抗値は変動しない。 The first magnetoresistive element 24c connected in series with the first magnetoresistive element 24a and spaced apart from the center of the first magnetoresistive element 24a by the first magnetoresistive element 24c It becomes the positional relationship in which the centers of the S poles of the permanent magnet 21 face each other. At this time, in the free magnetic layer 33 of the third magnetoresistive element 24c, the vector component of the external magnetic fields H5 and H6 in the (+) direction and the (−) direction is the Z2 direction (upward in the drawing) in the drawing. The external magnetic field H8 of the vector component flows into dominantly. Since the external magnetic field H8 is perpendicular to the film surface of the third magnetoresistive element 24c (a surface parallel to the XY plane), the magnetization direction 33a of the free magnetic layer 33 does not vary, The relationship orthogonal to the magnetization direction (PIN direction) of the pinned magnetic layer 31 is maintained. Therefore, the same state as the non-magnetic field state where the external magnetic field H is not acting acts on the third magnetoresistive element 24c, and the electric resistance value of the third magnetoresistive element 24c does not fluctuate.

図３の状態では、第１の磁気抵抗効果素子２４ａ及び第３の磁気抵抗効果素子２４ｃのみならず、Ａ相のブリッジ回路を構成する他の第５の磁気抵抗効果素子２４ｅ及び第７の磁気抵抗効果素子２４ｇの電気抵抗値も変動しない。 In the state of FIG. 3, not only the first magnetoresistive effect element 24a and the third magnetoresistive effect element 24c but also the other fifth magnetoresistive effect element 24e and the seventh magnetism constituting the A-phase bridge circuit. The electrical resistance value of the resistive element 24g does not change.

よって図７に示す第１の出力取り出し部５０及び第２の出力取り出し部５１からは夫々中点電位が出力され、差動電位はゼロである。 Therefore, the first output extraction unit 50 and the second output extraction unit 51 shown in FIG. 7 each output a midpoint potential, and the differential potential is zero.

本実施形態では、前記フリー磁性層３３の磁化方向３３ａを無磁場状態において、前記固定磁性層３１の磁化方向（ＰＩＮ方向）と直交する方向に規制し、図８に示すヒステリシスのないＲ−Ｈ曲線４０を得ることが出来る。図１１，図１２で説明した従来構造では、無磁場状態でのフリー磁性層の磁化の不安定化によって磁気抵抗効果素子の電気抵抗値がばらつき、その結果、出力波形に乱れが生じたが、本実施形態では、従来に比べて出力波形の乱れを改善でき波形を平滑化できる。 In the present embodiment, the magnetization direction 33a of the free magnetic layer 33 is restricted to a direction orthogonal to the magnetization direction (PIN direction) of the pinned magnetic layer 31 in the absence of a magnetic field, and RH without hysteresis shown in FIG. A curve 40 can be obtained. In the conventional structure described with reference to FIGS. 11 and 12, the electric resistance value of the magnetoresistive effect element varies due to destabilization of the magnetization of the free magnetic layer in the absence of a magnetic field, and as a result, the output waveform is disturbed. In this embodiment, the disturbance of the output waveform can be improved compared to the conventional case, and the waveform can be smoothed.

次に、前記磁気センサ２２が図示Ｘ１方向にλ／２だけ相対移動すると図４のようになる。 Next, when the magnetic sensor 22 is relatively moved by λ / 2 in the X1 direction shown in FIG.

図４に示すように前記第１の磁気抵抗効果素子２４ａには、（−）方向の外部磁界Ｈ６のうち、図示Ｘ２方向へのベクトル成分の外部磁界Ｈ９が支配的に流入する。 As shown in FIG. 4, out of the external magnetic field H6 in the (−) direction, a vector component external magnetic field H9 in the X2 direction flows dominantly into the first magnetoresistive element 24a.

この結果、前記フリー磁性層３３の磁化方向３３ａは、固定磁性層３１の磁化方向（ＰＩＮ方向）と直交方向である図示Ｙ１方向（図２参照）から図示Ｘ２方向に磁化変動する。前記フリー磁性層３３の磁化方向３３ａは前記固定磁性層３１の磁化方向（ＰＩＮ方向）と逆方向であるから、前記第１の磁気抵抗効果素子２４ａの電気抵抗値は大きくなる。 As a result, the magnetization direction 33a of the free magnetic layer 33 changes in magnetization from the Y1 direction (see FIG. 2) perpendicular to the magnetization direction (PIN direction) of the pinned magnetic layer 31 to the X2 direction. Since the magnetization direction 33a of the free magnetic layer 33 is opposite to the magnetization direction (PIN direction) of the pinned magnetic layer 31, the electrical resistance value of the first magnetoresistive element 24a is increased.

一方、前記第１の磁気抵抗効果素子２４ａと直列接続され、図示Ｘ１方向にλの中心間距離を空けた位置にある第３の磁気抵抗効果素子２４ｃには、（＋）方向の外部磁界Ｈ５のうち、図示Ｘ１方向へのベクトル成分の外部磁界Ｈ１０が支配的に流入する。 On the other hand, an external magnetic field H5 in the (+) direction is connected to the third magnetoresistive element 24c that is connected in series with the first magnetoresistive element 24a and is spaced by a center distance of λ in the X1 direction shown in the figure. Among these, the external magnetic field H10 of the vector component in the X1 direction shown in FIG.

この結果、前記フリー磁性層３３の磁化方向３３ａは、固定磁性層３１の磁化方向（ＰＩＮ方向）と直交方向である図示Ｙ１方向（図２参照）から図示Ｘ１方向に磁化変動する。前記フリー磁性層３３の磁化方向３３ａは前記固定磁性層３１の磁化方向（ＰＩＮ方向）と同じ方向であるから、前記第３の磁気抵抗効果素子２４ａの電気抵抗値は小さくなる。 As a result, the magnetization direction 33a of the free magnetic layer 33 changes in magnetization from the Y1 direction (see FIG. 2) perpendicular to the magnetization direction (PIN direction) of the pinned magnetic layer 31 to the X1 direction. Since the magnetization direction 33a of the free magnetic layer 33 is the same as the magnetization direction (PIN direction) of the pinned magnetic layer 31, the electric resistance value of the third magnetoresistive element 24a becomes small.

また第１の磁気抵抗効果素子２４ａ及び第３の磁気抵抗効果素子２４ｃとブリッジ回路を構成する前記第５の磁気抵抗効果素子２４ｅには、前記第１の磁気抵抗効果素子２４ｅに流入する外部磁界Ｈ９が流入し、前記第７の磁気抵抗効果素子２４ｇには、前記第３の磁気抵抗効果素子２４ｃに流入する外部磁界Ｈ１０が流入する。 The fifth magnetoresistive effect element 24e constituting a bridge circuit with the first magnetoresistive effect element 24a and the third magnetoresistive effect element 24c has an external magnetic field flowing into the first magnetoresistive effect element 24e. H9 flows in, and the external magnetic field H10 flowing into the third magnetoresistive element 24c flows into the seventh magnetoresistive element 24g.

よって図７に示す第１の出力取り出し部５０からは、中点電位よりも低い電圧が出力され、前記第２の出力取り出し部５１からは、中点電位よりも高い電圧が出力される。そして差動電位を取ると電圧値が倍となる。 Therefore, a voltage lower than the midpoint potential is output from the first output extraction section 50 shown in FIG. 7, and a voltage higher than the midpoint potential is output from the second output extraction section 51. When the differential potential is taken, the voltage value is doubled.

Ａ相のブリッジ回路を構成する第１の磁気抵抗効果素子２４ａ、第３の磁気抵抗効果素子２４ｃ、第５の磁気抵抗効果素子２４ｅ及び第７の磁気抵抗効果素子２４ｇは、夫々、前記磁気センサ２２あるいは第１の永久磁石２１の移動により、電気抵抗値が変化し、第１の出力端子５９からは略矩形状の出力波形が得られる。 The first magnetoresistive effect element 24a, the third magnetoresistive effect element 24c, the fifth magnetoresistive effect element 24e, and the seventh magnetoresistive effect element 24g constituting the A-phase bridge circuit are respectively the magnetic sensor. 22 or the movement of the first permanent magnet 21 changes the electric resistance value, and a substantially rectangular output waveform is obtained from the first output terminal 59.

一方、Ｂ相のブリッジ回路を構成する第２の磁気抵抗効果素子２４ｂ、第４の磁気抵抗効果素子２４ｄ、第６の磁気抵抗効果素子２４ｆ及び第８の磁気抵抗効果素子２４ｈも、夫々、前記磁気センサ２２あるいは第１の永久磁石２１の移動により、電気抵抗値が変化し、第２の出力端子６１からは略矩形状の出力波形が得られる。 On the other hand, the second magnetoresistive effect element 24b, the fourth magnetoresistive effect element 24d, the sixth magnetoresistive effect element 24f and the eighth magnetoresistive effect element 24h constituting the B-phase bridge circuit are also respectively described above. Due to the movement of the magnetic sensor 22 or the first permanent magnet 21, the electric resistance value changes, and a substantially rectangular output waveform is obtained from the second output terminal 61.

前記第１の出力端子５９から出力される出力波形と、前記第２の出力端子６１から出力される出力波形は位相がずれている。出力により、前記磁気センサ２２あるいは第１の永久磁石２１の移動速度や移動距離を検出できる。またＡ相とＢ相のブリッジ回路を設けて出力を２系統にすることで、前記第１の出力端子５９からの出力波形に対する前記第２の出力端子６１からの出力波形の位相のずれ方向がどちら方向であるかにより、移動方向を知ることが可能である。 The output waveform output from the first output terminal 59 and the output waveform output from the second output terminal 61 are out of phase. Based on the output, the moving speed and moving distance of the magnetic sensor 22 or the first permanent magnet 21 can be detected. In addition, by providing A-phase and B-phase bridge circuits and providing two systems of output, the phase shift direction of the output waveform from the second output terminal 61 relative to the output waveform from the first output terminal 59 can be changed. It is possible to know the moving direction depending on which direction it is.

上記のようにフリー磁性層３３の磁化方向３３ａを、前記固定磁性層３１の磁化方向（ＰＩＮ方向）と直交する方向に制御することで、図３に示すＡ相のブリッジ回路に対する無磁場状態から図４の状態に変化したとき、第１の磁気抵抗効果素子２４ａのフリー磁性層３３、及び第３の磁気抵抗効果素子２４ｃのフリー磁性層３３の双方が、同じように磁化変動する。すなわちフリー磁性層３３は、（＋）方向の外部磁界Ｈ５が作用したときと、（−）方向の外部磁界Ｈ６が作用したときとで、磁気感度が夫々同じである。また、一方の磁気抵抗効果素子の電気抵抗値が大きくなれば、直列接続された他方の磁気抵抗効果素子の電気抵抗値は必ず下がる関係にある。したがって図１０に示す従来構造に比べて、（＋）方向の外部磁界Ｈ５及び（−）方向の外部磁界Ｈ６に対する磁気感度のアンバランスを改善できる。 As described above, the magnetization direction 33a of the free magnetic layer 33 is controlled to a direction orthogonal to the magnetization direction (PIN direction) of the pinned magnetic layer 31 so that the A-phase bridge circuit shown in FIG. When the state changes to the state of FIG. 4, both the free magnetic layer 33 of the first magnetoresistive effect element 24a and the free magnetic layer 33 of the third magnetoresistive effect element 24c fluctuate in the same manner. That is, the free magnetic layer 33 has the same magnetic sensitivity when the external magnetic field H5 in the (+) direction is applied and when the external magnetic field H6 in the (−) direction is applied. Further, when the electric resistance value of one magnetoresistive effect element is increased, the electric resistance value of the other magnetoresistive effect element connected in series is necessarily reduced. Therefore, compared with the conventional structure shown in FIG. 10, it is possible to improve the magnetic sensitivity imbalance with respect to the external magnetic field H5 in the (+) direction and the external magnetic field H6 in the (−) direction.

以上のように本実施形態では、出力波形の乱れを従来に比べて改善でき、また（＋）方向の外部磁界が作用したときと（−）方向の外部磁界が作用したときとで各磁気抵抗効果素子の検出感度を同じにでき、したがって従来に比べて検出精度を向上できる。 As described above, in this embodiment, the disturbance of the output waveform can be improved as compared with the conventional case, and each magnetoresistive resistance is increased when an external magnetic field in the (+) direction is applied and when an external magnetic field in the (−) direction is applied. The detection sensitivity of the effect element can be made the same, and therefore the detection accuracy can be improved as compared with the conventional case.

しかも本実施形態では、基板２３の裏面２３ｂに一つの第２の永久磁石２５を設け、全ての磁気抵抗効果素子２４ａ〜２４ｈのフリー磁性層３３の磁化方向３３ａを、前記第２の永久磁石２５からの同じバイアス磁界ｂｉａｓによって制御するので、簡単な構成で、前記フリー磁性層３３の磁化方向３３ａの制御を行うことが可能となっている。 In addition, in the present embodiment, one second permanent magnet 25 is provided on the back surface 23b of the substrate 23, and the magnetization direction 33a of the free magnetic layer 33 of all the magnetoresistive effect elements 24a to 24h is set to the second permanent magnet 25. Therefore, the magnetization direction 33a of the free magnetic layer 33 can be controlled with a simple configuration.

前記第２の永久磁石２５の図示Ｘ１−Ｘ２方向への幅寸法は、図示Ｘ１−Ｘ２方向に配列された磁気抵抗効果素子の両側に位置する第１の磁気抵抗効果素子２４ａと前記第４の磁気抵抗効果素子２４ｄ間の間隔、及び前記第５の磁気抵抗効果素子２４ｅと前記第８の磁気抵抗効果素子２４ｈ間の間隔よりも大きい。これによって全ての磁気抵抗効果素子２４ａ〜２４ｈに対して前記第２の永久磁石２５から同じバイアス磁界ｂｉａｓを印加でき、全ての磁気抵抗効果素子２４ａ〜２４ｈのフリー磁性層３３を適切に磁化制御できる。 The width dimension of the second permanent magnet 25 in the illustrated X1-X2 direction is such that the first magnetoresistive effect element 24a located on both sides of the magnetoresistive effect elements arranged in the illustrated X1-X2 direction and the fourth permanent magnet 25 have the fourth dimension. The distance between the magnetoresistive effect element 24d and the distance between the fifth magnetoresistive effect element 24e and the eighth magnetoresistive effect element 24h are larger. As a result, the same bias magnetic field bias can be applied from the second permanent magnet 25 to all the magnetoresistive effect elements 24a to 24h, and the free magnetic layers 33 of all the magnetoresistive effect elements 24a to 24h can be controlled appropriately. .

前記第２の永久磁石２５はバルク材であることが好ましい。例えば、前記第２の永久磁石２５は前記基板２３の裏面２３ｂに接着剤を介して貼り付けられる。 The second permanent magnet 25 is preferably a bulk material. For example, the second permanent magnet 25 is attached to the back surface 23b of the substrate 23 with an adhesive.

図２に示すように各磁気抵抗効果素子２４ａ〜２４ｈは、図示Ｘ１−Ｘ２方向の幅寸法Ｔ１よりも、図示Ｙ１−Ｙ２方向の長さ寸法Ｌ１のほうが長く形成されている。前記固定磁性層３１の磁化方向（ＰＩＮ方向）は、図示Ｘ１−Ｘ２方向に磁化され、前記フリー磁性層３３の磁化方向３３ａは、長手方向である図示Ｙ１−Ｙ２方向に磁化される。各磁気抵抗効果素子２４ａ〜２４ｈの幅寸法Ｔ１は、２〜１００μｍ程度、長さ寸法Ｌ１は１００〜３００μｍ程度である。このように長さ寸法Ｌ１が非常に長くなっている。よって例えば、前記磁気抵抗効果素子２４ａ〜２４ｈの図示Ｙ１−Ｙ２方向の両側に、ＣｏＰｔ等のハードバイアス層をスパッタ法で形成して、前記ハードバイアス層によるバイアス磁界によって前記フリー磁性層３３を図示Ｙ１方向に磁化するには、前記バイアス磁界が弱すぎ、前記フリー磁性層３３を適切に磁化制御できない。したがって本実施形態ではバルク材の第２の永久磁石２５を用いている。そして、これにより、全ての前記フリー磁性層３３の磁化制御を一度に行うことが出来る。 As shown in FIG. 2, each of the magnetoresistive elements 24a to 24h is formed such that the length dimension L1 in the illustrated Y1-Y2 direction is longer than the width dimension T1 in the illustrated X1-X2 direction. The magnetization direction (PIN direction) of the pinned magnetic layer 31 is magnetized in the illustrated X1-X2 direction, and the magnetization direction 33a of the free magnetic layer 33 is magnetized in the illustrated Y1-Y2 direction, which is the longitudinal direction. Width T1 of each magnetoresistive element 24a~24h is about 2 ～100Myuemu, the length L1 is about 100 to 300 [mu] m. Thus, the length dimension L1 is very long. Therefore, for example, a hard bias layer such as CoPt is formed by sputtering on both sides of the magnetoresistive elements 24a to 24h in the Y1-Y2 direction, and the free magnetic layer 33 is illustrated by a bias magnetic field generated by the hard bias layer. In order to magnetize in the Y1 direction, the bias magnetic field is too weak to properly control the magnetization of the free magnetic layer 33. Therefore, in this embodiment, the second permanent magnet 25 made of a bulk material is used. Thereby, the magnetization control of all the free magnetic layers 33 can be performed at a time.

前記第２の永久磁石２５から前記フリー磁性層３３に作用するバイアス磁界ｂｉａｓの大きさは、前記第１の永久磁石２１から前記フリー磁性層３３に作用する外部磁界Ｈの大きさに比べて小さい。これによって前記フリー磁性層３３は、適切に前記第１の永久磁石２１からの外部磁界Ｈによって磁化変動する。 The magnitude of the bias magnetic field bias that acts on the free magnetic layer 33 from the second permanent magnet 25 is smaller than the magnitude of the external magnetic field H that acts on the free magnetic layer 33 from the first permanent magnet 21. . Accordingly, the free magnetic layer 33 is appropriately changed in magnetization by the external magnetic field H from the first permanent magnet 21.

また、図６に示すように、前記基板２３と磁気抵抗効果素子２４ａ〜２４ｈとを有する磁気センサ２２を収納した筐体７０の外側に、前記第２の永久磁石２５を設けてもよい。 In addition, as shown in FIG. 6, the second permanent magnet 25 may be provided outside the housing 70 that houses the magnetic sensor 22 having the substrate 23 and the magnetoresistive elements 24a to 24h.

本実施形態の磁気エンコーダ２０は、図１に示すように磁気センサ２２が第１の永久磁石２１に対して直線的に相対移動するものであったが、図９に示すように、例えば表面８０ａにＮ極とＳ極とが交互に着磁された回転ドラム８０と前記磁気センサ２２とを有し、前記回転ドラム８０の回転によって得られた出力により、回転速度や回転数、回転方向を検知できる回転型の磁気エンコーダであってもよい。 In the magnetic encoder 20 of the present embodiment, the magnetic sensor 22 linearly moves relative to the first permanent magnet 21 as shown in FIG. 1, but as shown in FIG. The rotating drum 80 in which N poles and S poles are alternately magnetized and the magnetic sensor 22, and the rotation speed, the number of rotations, and the rotating direction are detected by the output obtained by the rotation of the rotating drum 80. A rotary magnetic encoder that can be used may be used.

図９の拡大図に示すように、図１に示す直線移動の磁気エンコーダと同様に、Ｎ極とＳ極の中心間距離（ピッチ）をλとしたとき、直列接続される各磁気抵抗効果素子どうしの中心間距離はλに制御されている。 As shown in the enlarged view of FIG. 9, each magnetoresistive element connected in series when the distance (pitch) between the centers of the N pole and the S pole is λ, similar to the linearly moving magnetic encoder shown in FIG. The distance between the centers is controlled to λ.

図９に示すように、各磁気抵抗効果素子２４ａ〜２４ｈの固定磁性層３１の磁化方向（ＰＩＮ方向）は、前記磁気センサ２２の基板２３の中心を、前記磁気センサ２２の相対回転方向上の接点としたときの接線方向と平行な方向に固定されている。ここで「接線方向」とは、接線に方向性を持たせたものであり、その方向は、相対回転方向に従う。換言すれば、前記接線方向は、前記接点での速度ベクトルの方向である。前記固定磁性層３１の磁化方向は、前記接線方向に反平行であってもよい。 As shown in FIG. 9, the magnetization direction (PIN direction) of the pinned magnetic layer 31 of each of the magnetoresistive effect elements 24 a to 24 h is centered on the substrate 23 of the magnetic sensor 22 and on the relative rotational direction of the magnetic sensor 22. It is fixed in a direction parallel to the tangential direction when the contact is made. Here, the “tangential direction” is a direction in which the tangent is given directionality, and the direction follows the relative rotation direction. In other words, the tangential direction is the direction of the velocity vector at the contact. The magnetization direction of the pinned magnetic layer 31 may be antiparallel to the tangential direction.

また図７に示すように本実施形態では、Ａ相とＢ相のブリッジ回路が設けられているが、どちらか一方だけ設けられる形態でもよい。 Further, as shown in FIG. 7, in the present embodiment, a bridge circuit of A phase and B phase is provided, but only one of them may be provided.

また本実施形態の磁気エンコーダでは、直列接続される磁気抵抗効果素子の中心間の間隔はλであったが、これに限定されるものではない。かかる場合、全ての固定磁性層の磁化方向は平行でなくてもよい。少なくとも一つの磁気抵抗効果素子における固定磁性層の磁化方向が、残りの磁気抵抗効果素子における固定磁性層の磁化方向に対して反平行であってもよい。例えば図２に示す第１の磁気抵抗効果素子２４ａの固定磁性層３１の磁化方向は図示Ｘ１方向であるが、第３の磁気抵抗効果素子２４ｃの固定磁性層３１の磁化方向は図示Ｘ２方向である如くである。ただし、図２に示すように、直列接続される磁気抵抗効果素子の中心間の間隔をλとし、各磁気抵抗効果素子２４ａ〜２４ｈの固定磁性層３１の磁化方向（ＰＩＮ方向）を全て同一方向に磁化することが前提の磁気エンコーダに本実施形態は効果的に適用できる。 In the magnetic encoder of the present embodiment, the interval between the centers of the magnetoresistive elements connected in series is λ, but is not limited to this. In such a case, the magnetization directions of all the pinned magnetic layers may not be parallel. The magnetization direction of the pinned magnetic layer in at least one magnetoresistive element may be antiparallel to the magnetization direction of the pinned magnetic layer in the remaining magnetoresistive elements. For example, the magnetization direction of the pinned magnetic layer 31 of the first magnetoresistive effect element 24a shown in FIG. 2 is the X1 direction shown in the figure, but the magnetization direction of the pinned magnetic layer 31 of the third magnetoresistive effect element 24c is the X2 direction shown in the figure. There seems to be. However, as shown in FIG. 2, the interval between the centers of the magnetoresistive effect elements connected in series is λ, and the magnetization directions (PIN directions) of the pinned magnetic layers 31 of the magnetoresistive effect elements 24a to 24h are all in the same direction. The present embodiment can be effectively applied to a magnetic encoder that is premised on magnetization.

本実施形態の磁気センサ２２は、磁気エンコーダ以外に、例えば、ポテンショメータにも適用することが出来る。ポテンショメータでは磁気センサの基板に垂直な軸を中心として回転可能な磁石（磁界発生部材）が対向配置される。前記磁石の回転により、各磁気抵抗効果素子に回転磁場が作用し各磁気抵抗効果素子の電気抵抗値が変化する。前記電気抵抗値の変化に基づく出力波形から前記磁石の回転角度を検知できる。 The magnetic sensor 22 of the present embodiment can be applied to, for example, a potentiometer in addition to the magnetic encoder. In the potentiometer, a magnet (magnetic field generating member) that can rotate about an axis perpendicular to the substrate of the magnetic sensor is disposed oppositely. Due to the rotation of the magnet, a rotating magnetic field acts on each magnetoresistive element and the electric resistance value of each magnetoresistive element changes. The rotation angle of the magnet can be detected from the output waveform based on the change in the electrical resistance value.

本実施形態の磁気エンコーダの部分斜視図、The partial perspective view of the magnetic encoder of this embodiment, 磁気センサの部分拡大平面図、Partial enlarged plan view of the magnetic sensor, 図２に示すＡ−Ａ線から膜厚方向に切断し矢印方向から見た前記磁気エンコーダの部分拡大断面図、The partial expanded sectional view of the said magnetic encoder cut | disconnected in the film thickness direction from the AA line shown in FIG. 図３の状態から磁気センサが、λ／２だけ相対移動したときの前記磁気エンコーダの部分拡大断面図、FIG. 3 is a partial enlarged cross-sectional view of the magnetic encoder when the magnetic sensor is relatively moved by λ / 2 from the state of FIG. 3; 図２に示すＢ−Ｂ線から膜厚方向に切断し矢印方向から見た前記磁気センサの拡大断面図、FIG. 2 is an enlarged cross-sectional view of the magnetic sensor as viewed from the direction of the arrow cut in the film thickness direction from the line BB shown in FIG. 図５の変形例を示す磁気センサの断面図、Sectional drawing of the magnetic sensor which shows the modification of FIG. 磁気センサの回路図、Circuit diagram of magnetic sensor, 磁気抵抗効果素子のＲ−Ｈ曲線を示すグラフ、A graph showing an RH curve of the magnetoresistive element; 本実施の別の形態の磁気エンコーダの模式図、Schematic diagram of a magnetic encoder of another embodiment of the present embodiment, 従来における第１の磁気エンコーダの構造と問題点を説明するための部分断面図、Partial sectional view for explaining the structure and problems of a first magnetic encoder in the prior art, 従来における第２の磁気エンコーダの構造と問題点を説明するための部分断面図、Partial sectional view for explaining the structure and problems of the second magnetic encoder in the prior art, 図１１の磁気エンコーダに搭載される磁気抵抗効果素子のＨ／／ＰＩＮ方向のＲ−Ｈ曲線を示すグラフ、The graph which shows the RH curve of the H // PIN direction of the magnetoresistive effect element mounted in the magnetic encoder of FIG.

Explanation of symbols

２０磁気エンコーダ
２１第１の永久磁石
２２磁気センサ
２３基板
２４ａ〜２４ｈ磁気抵抗効果素子
２５第２の永久磁石
３０反強磁性層
３１固定磁性層
３２非磁性材料層
３３フリー磁性層
３４保護層
４０Ｒ−Ｈ曲線
７０筐体
５０、５１、５４、５５出力取り出し部
５２、５６入力端子
５３、５７アース端子
５８、６０差動増幅器
５９、６１出力端子
８０回転ドラム
３３ａ（フリー磁性層の）磁化方向
ＰＩＮ（固定磁性層の）磁化方向 20 Magnetic encoder 21 First permanent magnet 22 Magnetic sensor 23 Substrate 24a-24h Magnetoresistive element 25 Second permanent magnet 30 Antiferromagnetic layer 31 Fixed magnetic layer 32 Nonmagnetic material layer 33 Free magnetic layer 34 Protective layer 40 R -H curve 70 Case 50, 51, 54, 55 Output take-out part 52, 56 Input terminal 53, 57 Ground terminal 58, 60 Differential amplifier 59, 61 Output terminal 80 Rotating drum 33a Magnetization direction PIN (of free magnetic layer) Magnetization direction (of pinned magnetic layer)

Claims

A magnetic sensor having a magnetoresistive effect element using a magnetoresistive effect that changes an electric resistance value with respect to an external magnetic field from a magnetic field generating member on a substrate,
A plurality of the magnetoresistive effect elements are provided on the substrate, and a fixed magnetic layer whose magnetization is fixed in one direction and a free magnetic layer whose magnetization is fluctuated with respect to the external magnetic field are a nonmagnetic material layer. Having a laminated portion laminated through,
The magnetization direction of the pinned magnetic layer in all the magnetoresistive effect elements is parallel, or the magnetization direction of the pinned magnetic layer in at least one of the magnetoresistive effect elements is the pinned in the remaining magnetoresistive effect elements. Antiparallel to the magnetization direction of the magnetic layer,
A permanent magnet is provided at a position away from the magnetoresistive effect element, and the free magnetic layer of all the magnetoresistive effect elements is separated from the permanent magnet in a no-magnetic field state where an external magnetic field from the magnetic field generating member does not act. The magnetic sensor is magnetized by the same bias magnetic field in the direction perpendicular to the magnetization direction of the pinned magnetic layer and in the same direction as the action direction of the bias magnetic field .

The magnetic sensor according to claim 1, wherein the magnetoresistive effect element is provided on a surface of the substrate, and the permanent magnet is provided on a back surface of the substrate.

The magnetoresistive effect element has a shape in which the dimension in the length direction perpendicular to the width direction is longer than the dimension in the width direction, and the pinned magnetic layer is magnetization-fixed in the width direction and free magnetic The magnetic sensor according to claim 1, wherein the layer is magnetized in the length direction.

A magnetic encoder comprising a magnetic field generating member having a magnetized surface in which N and S poles are alternately magnetized on the surface, and the magnetic sensor according to any one of claims 1 to 3,
The N pole and the S pole are alternately arranged in the relative movement direction or the relative rotation direction of the magnetic sensor, and the relative movement direction or the relative rotation direction is provided to the magnetic sensor in accordance with the relative movement or the relative rotation. The external magnetic field in the (+) direction toward the direction and the external magnetic field in the (−) direction opposite to the (+) direction act alternately,
The magnetoresistive effect elements connected in series are displaced in a direction parallel to the relative movement direction or in a direction parallel to a tangential direction when the center of the substrate is a contact point in the relative rotation direction. ,
The fixed magnetic layer of each magnetoresistive element is magnetized and fixed in a direction parallel or antiparallel to the relative movement direction, or in a direction parallel or antiparallel to the tangential direction, respectively. Encoder.

When the distance between the centers of the N pole and the S pole is λ, the magnetoresistive elements connected in series are in a direction parallel to the relative movement direction or in a direction parallel to the tangential direction. It is arranged with a distance between the centers of
The magnetic encoder according to claim 4, wherein the fixed magnetic layers of all magnetoresistive elements are fixed in magnetization in the same direction.