JPH07181239A - Magnetic impedance effect element - Google Patents
Magnetic impedance effect elementInfo
- Publication number
- JPH07181239A JPH07181239A JP5323816A JP32381693A JPH07181239A JP H07181239 A JPH07181239 A JP H07181239A JP 5323816 A JP5323816 A JP 5323816A JP 32381693 A JP32381693 A JP 32381693A JP H07181239 A JPH07181239 A JP H07181239A
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- JP
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- Prior art keywords
- magnetic
- wire
- magnetic line
- magnetic wire
- voltage
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Measuring Magnetic Variables (AREA)
- Magnetic Heads (AREA)
- Soft Magnetic Materials (AREA)
- Transmission And Conversion Of Sensor Element Output (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】この発明は、磁気インピーダンス
効果素子に関するものである。さらに詳しくは、この発
明は、オーディオテープレコーダ、ビデオテープレコー
ダ、コンピュータ、計測制御機器であるロータリエンコ
ーダ、数値制御機器の磁気スケールなどに用いられてい
る磁気ヘッドや各種の磁気センサ等として有用な磁気イ
ンピーダンス効果素子に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-impedance effect element. More specifically, the present invention is useful as a magnetic head and various magnetic sensors used in audio tape recorders, video tape recorders, computers, rotary encoders that are measurement control devices, magnetic scales of numerical control devices, and various magnetic sensors. The present invention relates to an impedance effect element.
【０００２】[0002]
【従来の技術とその課題】マイクロエレクトロニクス技
術の発展にともなって、ＡＶ機器、コンピュータ、計測
制御機器、数値制御機器等の小型高性能化が急速に進ん
でいる。特にコンピュータ関連機器に関してはそれが顕
著であり、たとえば、コンピュータ用外部記憶媒体であ
るフロッピーディスクについてみると、直径が５インチ
のものから、さらに小型化が進み、今や２．８インチ時
代を迎えようとしている。また、ハードディスクでは１
インチ径のものに移行しようとしている。2. Description of the Related Art With the development of microelectronics technology, miniaturization and high performance of AV equipments, computers, measurement control equipments, numerical control equipments, etc. are rapidly advancing. This is especially the case with computer-related equipment. For example, when it comes to floppy disks, which are external storage media for computers, those with a diameter of 5 inches are becoming smaller, and the 2.8-inch era will now be reached. I am trying. Also, for hard disks, 1
I am trying to shift to the inch diameter one.
【０００３】しかしながら、これらの各機器を小型化す
るには、その心臓部である磁気ヘッドを小型化する必要
があるが、この磁気ヘッドの小型化は必ずしも容易では
なく、これを妨げる要因がある。ひとつの要因は、磁気
ヘッド自体の大きさの問題である。つまり、従来の磁気
ヘッドはコイルの巻線が必要であり、磁気ヘッド自体は
どうしても大型化してしまう。もうひとつは、検出感度
の問題である。つまり、小型化されると磁気ヘッドと記
憶媒体の相対速度が低下して検出速度が小さくなり、し
たがって、検出感度が著しく低下してしまうということ
である。However, in order to miniaturize each of these devices, it is necessary to miniaturize the magnetic head, which is the heart of the equipment. However, miniaturization of the magnetic head is not always easy and there are factors that hinder this. . One factor is the size of the magnetic head itself. That is, the conventional magnetic head requires the winding of the coil, and the magnetic head itself inevitably becomes large. The other is the problem of detection sensitivity. In other words, when the size is reduced, the relative speed between the magnetic head and the storage medium is reduced and the detection speed is reduced, and therefore the detection sensitivity is significantly reduced.
【０００４】そこで、最近になって、従来の磁気ヘッド
では検出電圧が不足してくるため、磁束の時間変化でな
く磁束そのものを検出する磁気抵抗素子をヘッドとして
使用する動きが見られるようになってきた。これによ
り、小型化が一層押し進められてきた。ところが、現在
の磁気抵抗素子は電気抵抗の変化率が最大６％以下と非
常に小さく、また、数％の磁気抵抗変化を生じさせるの
に必要な外部磁界は、２０ガウス以上と大きい。このた
め、磁気抵抗感度は、０．１％／Ｇ以下の低感度であ
り、このため信号対雑音比（Ｓ／Ｎ比）も非常に悪い。Therefore, recently, since the detection voltage becomes insufficient in the conventional magnetic head, there is a tendency to use a magnetoresistive element for detecting the magnetic flux itself as a head instead of the time change of the magnetic flux. Came. This has promoted further miniaturization. However, the current magnetoresistive element has a very small change rate of the electric resistance of 6% or less at the maximum, and the external magnetic field required to cause the change of the magnetic resistance of several% is as large as 20 gauss or more. Therefore, the magnetoresistive sensitivity is as low as 0.1% / G or less, and therefore the signal-to-noise ratio (S / N ratio) is also very poor.
【０００５】従って、磁気抵抗素子はブリッジ回路で抵
抗変化のみを検出できるようにした上で着磁体に十分近
接させて用いる必要があるが、実際には、たとえば、ス
ピンドルモータなどのロータリエンコーダにおいては、
ギャップマージンが数十ミクロン程度しかなく、細かい
ゴミの侵入によってもモータが停止するといった故障が
生じ易い状態となっている。 このような磁気抵抗素子
に対し、最近になって、巨大磁気抵抗効果とよばれる現
象が磁性人工格子を用いる場合に見出されているが、こ
の場合には、実際のところ、数十％の電気抵抗変化を得
るのに数百ガウスもの大きな磁界が必要であり、さら
に、ヒステリシスの問題もあり、小型化を指向する製品
にはこの技術は適していない。Therefore, it is necessary to use the magnetoresistive element in such a manner that only the resistance change can be detected by the bridge circuit and it is used sufficiently close to the magnetized body. However, in practice, for example, in a rotary encoder such as a spindle motor. ,
Since the gap margin is only about several tens of microns, the motor is likely to stop due to the intrusion of fine dust, which causes a failure. For such a magnetoresistive element, a phenomenon called a giant magnetoresistive effect has recently been found in the case where a magnetic artificial lattice is used. A large magnetic field of several hundred gauss is required to obtain the change in electric resistance, and there is a problem of hysteresis, and this technique is not suitable for products aiming at miniaturization.
【０００６】そこで、このような従来の磁性抵抗素子や
巨大抵抗効果を用いた素子の欠点を克服することのでき
る新しい素子をこの発明の発明者はすでに提案してい
る。すなわち、まず、一般的に、磁性を持つ導線に交流
電流などの時間的に変化する電流を流すと、導線の両端
には二種類の電圧の和が現われる。それらは導線の電気
抵抗と電流との積による電圧と、円周磁束の時間変化に
よる電圧である。つまり、磁性線両端間の交流電圧ｅw
は一般に磁性線の電気抵抗Ｒによるオーミック電圧ｅR
＝Ｒ・ｉw と磁性線円周方向磁束φθの時間変化ｄφθ
／ｄｔによる誘電電圧ｅL ＝ｄφB ／ｄｔの２つの成分
の和 ｅW ＝ｅR ＋ｅL で表わせられる。通常後者の電圧は非常に小さいので、
この電圧を利用することは、現在まで工学的にほとんど
なかった。Therefore, the inventor of the present invention has already proposed a new element capable of overcoming the drawbacks of the conventional magnetoresistive element and the element using the giant resistance effect. That is, generally, when a time-varying current such as an alternating current is passed through a magnetic conducting wire, a sum of two kinds of voltages appears at both ends of the conducting wire. They are the voltage due to the product of the electrical resistance of the conductor and the current, and the voltage due to the temporal change of the circumferential magnetic flux. That is, the AC voltage ew across the magnetic wire
Is generally the ohmic voltage eR due to the electrical resistance R of the magnetic wire
= R · iw and magnetic flux circumferential direction magnetic flux φθ change with time dφθ
The sum of the two components of the dielectric voltage eL = d.phi.B / dt due to / dt is represented by eW = eR + eL. The latter voltage is usually very small, so
Until now, there has been almost no engineering use of this voltage.
【０００７】そこで、すでに発明者が提案した新しい素
子は、時間的に変化する電流を磁性線に印加することに
よって生じる円周磁束の時間変化に対する電圧のみを、
外部印加磁界による変化として検出することを基本的な
原理としている磁気インダクタンス素子である。この磁
気インダクタンス素子は、磁性線と、その磁性線の円周
磁束の時間変化に対する電圧のみを取出す電気抵抗回路
とからなる。図１はその磁気インダクタンス素子の例を
示したものである。この図１の回路内の磁性線として、
図２に示すように、FeCoSiB 等からなる零磁歪アモルフ
ァス細線等を折り曲げたものや直線状のものを用いるこ
ともできる。Therefore, in the new element already proposed by the inventor, only the voltage with respect to the time change of the circumferential magnetic flux generated by applying a time-varying current to the magnetic wire,
It is a magnetic inductance element whose basic principle is to detect it as a change due to an externally applied magnetic field. This magnetic inductance element is composed of a magnetic wire and an electric resistance circuit that extracts only the voltage with respect to the time change of the circumferential magnetic flux of the magnetic wire. FIG. 1 shows an example of the magnetic inductance element. As the magnetic wire in the circuit of FIG. 1,
As shown in FIG. 2, a zero magnetostrictive amorphous thin wire made of FeCoSiB or the like may be bent or linear.
【０００８】このような磁気インダクタンス素子内の回
路により、磁性線に交流電流などの時間的に変化する電
流（Iw）を印加し、電気抵抗分による電圧（オーミック
電圧）を相殺することでインダクタンス分電圧（ｅL )
を得ることができる。この磁気インダクタンス素子の磁
性線に、外部から、たとえば、永久磁石やその他の手段
で発生される一般的な直流磁界や交流磁界を印加するこ
とによって、ｅL の振幅 ｜ｅL ｜ が減少し、外部印加磁界を検知することができる。By the circuit in the magnetic inductance element as described above, a time-varying current (Iw) such as an alternating current is applied to the magnetic wire and the voltage (ohmic voltage) due to the electric resistance is canceled to cancel the inductance. Voltage (eL)
Can be obtained. By applying a general direct-current magnetic field or alternating-current magnetic field generated by, for example, a permanent magnet or other means to the magnetic wire of this magnetic inductance element from the outside, the amplitude | eL | of eL decreases and the external application A magnetic field can be detected.
【０００９】この磁気インダクタンス素子において、た
とえば、磁性線としてFeCoSiB からなるas-cast の零磁
歪ａ−ワイヤを用い、磁性線に平行方向に印加した外部
磁界Ｈ1 と、ワイヤの長さを変化させて、各インダクタ
ンス分電圧ｅL の振幅 ｜ｅL ｜ を測定すると、図３に示すようになる。In this magnetic inductance element, for example, an as-cast zero magnetostrictive a-wire made of FeCoSiB is used as the magnetic wire, and the external magnetic field H1 applied in the direction parallel to the magnetic wire and the length of the wire are changed. When the amplitude | eL | of each inductance component voltage eL is measured, it becomes as shown in FIG.
【００１０】この図３において、（ａ）はワイヤの長さ
が３０mm、（ｂ）はワイヤの長さが１０mm、（ｃ）はワ
イヤの長さが５mm、（ｄ）はワイヤの長さが２mmの磁気
インダクタンス素子について、各 ｜ｅL ｜ を測定したものである。In FIG. 3, (a) shows a wire length of 30 mm, (b) shows a wire length of 10 mm, (c) shows a wire length of 5 mm, and (d) shows a wire length. Each | eL | was measured for a 2 mm magnetic inductance element.
【００１１】たとえば、図３（ａ）に示したように、３
０mm長のａ−ワイヤではＨ1 が約１（Oe) における ｜ｅL ｜ は、Ｈ1 が０（Oe) における ｜ｅL0｜ に対して、約５０％減少しており、従来のフラックスゲ
ート形磁界センサと同程度の高感度を示している。この
とき、ワイヤの長さ方向に対して垂直方向のＨ2を印加
すると ｜ｅL ｜ はほとんど変化しない。すなわち、磁気インダクタンス
素子は強い指向性を持っており、被検出信号磁界のみを
選択的に検出するので方位センサなどに適用する場合、
Ｓ／Ｎ比は著しく高くなる。また、張力アニールを施し
たアモルファスワイヤでは１〜２mmの長さでも図３
（ａ）のような高感度の電圧変化特性も見出した。For example, as shown in FIG.
In the 0 mm long a-wire, | eL | at H1 of about 1 (Oe) is about 50% less than that of | eL0 | at H1 of 0 (Oe), which is lower than that of the conventional fluxgate type magnetic field sensor. It shows the same high sensitivity. At this time, when H2 in the direction perpendicular to the length direction of the wire is applied, | eL | hardly changes. That is, since the magnetic inductance element has a strong directivity and selectively detects only the detected signal magnetic field, when applied to a direction sensor or the like,
The S / N ratio becomes extremely high. In addition, even if the amorphous wire subjected to tension annealing has a length of 1 to 2 mm,
The high-sensitivity voltage change characteristic as shown in (a) was also found.
【００１２】しかしながら、その後のこの発明の発明者
の検討により、この新しい素子にも、改善すべき点が存
在することがわかってきた。それは、この磁気インダク
タンス素子においは、磁気抵抗素子を用いる場合と同様
にブリッジ回路という補償回路が必要であり、そのため
に小型化にはおのずと限界があったからである。また、
補償回路の調整に手間がかかり、操作性に難点があっ
た。However, subsequent studies by the inventor of the present invention have revealed that this new device also has some points to be improved. This is because this magnetic inductance element requires a compensating circuit called a bridge circuit as in the case of using a magnetic resistance element, and therefore there was a natural limit to miniaturization. Also,
Adjustment of the compensation circuit was troublesome, and there was a difficulty in operability.
【００１３】この発明は、以上の通りの事情に鑑みてな
されたものであり、従来の磁気抵抗素子の欠点を克服
し、磁気抵抗素子と同程度の微小寸法でフラックスゲー
トセンサと同程度の高感度をもつ新しいマイクロ磁気素
子を提供することを目的としている。The present invention has been made in view of the circumstances as described above, overcomes the drawbacks of the conventional magnetoresistive element, and has a minute size comparable to that of the magnetoresistive element and a height comparable to that of the fluxgate sensor. The object is to provide a new micro magnetic element with sensitivity.
【００１４】[0014]
【課題を解決するための手段】この発明は、上記の課題
を解決するための手段として、時間的に変化する電流を
磁性線に印加することによって生じる円周磁束の時間変
化に対する電圧を外部印加磁界によって変化させる磁気
素子において、時間的に変化する電流を高周波とする磁
気インピーダンス効果素子を提供する。As a means for solving the above-mentioned problems, the present invention externally applies a voltage with respect to a time change of a circumferential magnetic flux generated by applying a time-varying current to a magnetic wire. Provided is a magneto-impedance effect element in which a time-varying current has a high frequency in a magnetic element changed by a magnetic field.
【００１５】[0015]
【作用】つまり、この発明においは、従来の磁気インダ
クタンス素子における通電電流を高周波化することによ
り、ブリッジ回路を不要としたことに大きな特徴があ
る。例えば、図４はこの発明を実現するための最も単純
な電気回路であり、磁性線に交流電流ｉw を通電して、
磁性線の平行方向から外部磁界（Ｈext ）を印加し、磁
性線の両端間の交流電圧の振幅｜ｅw ｜を測定する構成
をなしている。That is, the present invention is characterized in that the bridge circuit becomes unnecessary by increasing the frequency of the current flowing through the conventional magnetic inductance element. For example, FIG. 4 shows the simplest electric circuit for realizing the present invention, in which an alternating current iw is applied to a magnetic wire,
An external magnetic field (Hext) is applied from the direction parallel to the magnetic wire, and the amplitude | ew | of the AC voltage across the magnetic wire is measured.
【００１６】この発明においては、例えば図４におい
て、電気抵抗Ｒに磁性線のインピーダンスの数倍以上の
大きな抵抗値を持たせ、磁性線に通電した交流電流ｉw
の波形が交流電圧源の電圧ｅacの波形にほぼ等しくなる
ようにすることが望ましい。この発明においては、磁性
線としてアモルファス磁性線を使用することを特徴とす
る磁気インピーダンス効果素子を用いてもよく、さら
に、そのアモルファス磁性線として、円周方向に磁化容
易方向をもつアモルファス磁性線を用いてもよい。また
さらに、そのアモルファス磁性線として、正磁歪をもつ
アモルファス磁性線には長さ方向に圧縮力、負磁歪をも
つアモルファス磁性線には長さ方向に張力を印加して熱
処理を施したアモルファス磁性線を用いてもよい。In the present invention, for example, in FIG. 4, the electric resistance R is given a large resistance value which is several times or more the impedance of the magnetic wire, and the alternating current iw passed through the magnetic wire.
It is desirable that the waveform of is almost equal to the waveform of the voltage eac of the AC voltage source. In the present invention, a magneto-impedance effect element characterized by using an amorphous magnetic wire as the magnetic wire may be used. Furthermore, as the amorphous magnetic wire, an amorphous magnetic wire having an easy magnetization direction in the circumferential direction may be used. You may use. Further, as the amorphous magnetic wire, an amorphous magnetic wire having a positive magnetostriction is subjected to a heat treatment by applying a compressive force in the length direction and an amorphous magnetic wire having a negative magnetostriction is applied with a tension in the length direction. May be used.
【００１７】以下実施例を示しさらに詳しくこの発明に
ついて説明する。The present invention will be described in more detail with reference to the following examples.
【００１８】[0018]
実施例１ 実際にこの発明の磁気インピーダンス効果素子につい
て、アモルファス磁性線を高周波電流ｉw で通電励磁
し、外部磁界を印加した場合の、オーミック電圧ｅr と
誘電圧ｅL との和ｅw の振幅｜ｅw ｜の値を測定した。Example 1 In the magneto-impedance effect element of the present invention, the amplitude | ew | The value of was measured.
【００１９】例えば図５は、直径が３０μｍ、長さ５．
５ｍｍのアモルファス磁性線を１００ｋＨｚ以上のｉw
で通電励磁し、Ｈext ＝０（Oe）と、Ｈext ＝10（Oe）
（８００Ａ／ｍ）の外部磁界を印加した場合の、オーミ
ック電圧ｅr と誘電圧ｅL との和ｅw の振幅｜ｅw ｜の
値を示した結果である。この図５において、実線はＨex
t ＝０（Oe）の場合、点線はＨext ＝10（Oe）（８００
Ａ／ｍ）の場合である。このアモルファス磁性線は、２
Kg/mm2の張力を印加し４７５℃、１min のアニールをア
ニールを施している。For example, in FIG. 5, the diameter is 30 μm and the length is 5.
5mm amorphous magnetic wire with iw of 100kHz or more
Energized and excited at Hext = 0 (Oe) and Hext = 10 (Oe)
It is the result of showing the value of amplitude | ew | of sum ew of ohmic voltage er and dielectric pressure eL when an external magnetic field of (800 A / m) is applied. In FIG. 5, the solid line is Hex
When t = 0 (Oe), the dotted line is Hext = 10 (Oe) (800
A / m). This amorphous magnetic wire is 2
Annealing is performed for 1 min at 475 ° C. by applying a tension of Kg / mm 2 .
【００２０】この図５に例示したように、｜ｅw ｜のＨ
ext の印加による変化は、ｆ＞２００ｋＨｚで出現し、
ｆ＝１〜２ＭＨｚでは、Ｈext ＝１０（Oe）の外部磁界
を印加した場合、｜ｅw ｜は約５０％の減少を示してい
る。このような現象はこれまでの磁性体ではみられなか
った現象であり、とくにＭＲ効果が小さい（１％以下）
アモルファス磁性線で現われたことはこれまでまったく
予想されなかったことである。 図６は図５のｆ＝１Ｍ
Ｈｚ，ｉw ＝１５ｍＡにおける、ｉW ，ｅw(Ｈext ＝
０) およびｅw(Ｈext ＝10（Oe）) の波形の写真であ
る。この図６に例示したように、正弦波電流に対して、
ｅW(Ｈext ＝０) の波形は角のある波形であり、ｅw(Ｈ
ext ＝10（Oe）) の波形はｉw の波形とほとんど同じで
ある。このｅw （Ｈert ＝０）の波形は正弦波から著し
くかけ離れた波形ではないのでｅw とｉw を正弦波と考
えた場合、磁性線インピーダンスをＺとすると｜ｅw ｜
のＨext に対する変化は｜Ｚ｜の変化とみなすことがで
きる。従って、この発明の磁気素子を磁気インピーダン
ス効果素子（Magneto-Impencance素子；ＭＩ素子）と呼
ぶことにした。実施例２ この発明の磁気インピーダンス効果素子について、アモ
ルファス磁性線を高周波電流ｉw で通電励磁し、外部印
加磁界の変化と｜ｅw ｜との関係である磁気インピーダ
ンス特性を調べた。As illustrated in FIG. 5, H of | ew |
The change due to the application of ext appears at f> 200 kHz,
At f = 1 to 2 MHz, when an external magnetic field of Hext = 10 (Oe) is applied, | ew | shows a decrease of about 50%. Such a phenomenon is a phenomenon that has not been observed in magnetic materials up to now, and the MR effect is particularly small (1% or less).
The appearance of amorphous magnetic wires has never been expected. FIG. 6 shows f = 1M of FIG.
IW, ew (Hext = 15 Hz, iw = 15 mA)
0) and ew (Hext = 10 (Oe)). As illustrated in FIG. 6, for sinusoidal current,
The waveform of ew (Hext = 0) is a waveform with corners, and ew (H
The waveform of ext = 10 (Oe)) is almost the same as the waveform of iw. Since the waveform of ew (Hert = 0) is not a waveform that is significantly different from the sine wave, assuming that ew and iw are sine waves, assuming that the magnetic wire impedance is Z, then | ew |
Can be regarded as a change in | Z |. Therefore, the magnetic element of the present invention is called a magneto-impedance effect element (Magneto-Impencance element; MI element). Example 2 With respect to the magneto-impedance effect element of the present invention, the amorphous magnetic wire was energized and excited by the high frequency current iw, and the magneto-impedance characteristic which is the relationship between the change of the externally applied magnetic field and | ew | was investigated.
【００２１】図７は実施例１で用いたアモルファス磁性
線の磁気インピーダンス特性であり、ｆ＝１ＭＨｚにお
いて、ｉw ＝７．５ｍＡおよび１５ｍＡの場合を測定し
た結果である。この図７に例示したように、｜ｅw ｜は
Ｈext ＝５（Oe）で約５０％減少しており、例えば図２
に例示した交流電流を通電した磁性線に両端間の電圧を
検出するだけのもっとも単純な回路を用いても、従来の
フラックスゲートセンサに匹敵する非常に高感度の磁束
検出素子を得ることが可能である。実施例３ アモルファスの磁性線の径を変化させた場合のΔ｜ｅw
｜／｜ｅw ｜の周波数特性を調べた。FIG. 7 shows the magnetic impedance characteristics of the amorphous magnetic wire used in Example 1, which is the result of measurement at i = 1 = 7.5 mA and 15 mA at f = 1 MHz. As illustrated in FIG. 7, | ew | is reduced by about 50% at Hext = 5 (Oe).
Even with the simplest circuit that detects the voltage across both ends of a magnetic wire that has been energized with an alternating current, the extremely sensitive magnetic flux detection element comparable to conventional flux gate sensors can be obtained. Is. Example 3 Δ | ew when the diameter of the amorphous magnetic wire was changed
The frequency characteristic of | / | ew | was investigated.
【００２２】図８は実施例１で用いたアモルファスの磁
性線を変化させた場合のΔ｜ｅw ｜／｜ｅw ｜の周波数
特性である。この図８に例示したように、１２４μｍ径
の磁性線および５０μｍ径の磁性線では、それぞれｆ＝
２００ＫＨｚおよび６００ｋＨｚ近傍で変化率は最大を
示した。特に、５０μｍ径の磁性線を用いた場合の変化
率は、この３つの中で最も大きくその値は約６０％を示
した。FIG. 8 shows the frequency characteristics of Δ | ew | / | ew | when the amorphous magnetic wire used in Example 1 was changed. As illustrated in FIG. 8, in the magnetic wire having a diameter of 124 μm and the magnetic wire having a diameter of 50 μm, f =
The maximum rate of change was shown near 200 kHz and 600 kHz. In particular, the rate of change when a magnetic wire with a diameter of 50 μm was used was the largest among these three values, and the value was about 60%.
【００２３】この磁気インピーダンス効果の起源は図５
に示した２曲線から考察すると磁性線の内部インダクタ
ンスＬi の変化と同時に磁性線の電気抵抗Ｒw が表皮効
果により変化するためと考えられる。すなわち、表皮効
果が強い場合（図５の実線ではｆ＞２００ＫＨＺ）には
インピーダンスＺは、δを表皮厚さ、ａを磁性線直径と
すると、The origin of this magneto-impedance effect is shown in FIG.
Considering from the two curves shown in FIG. 2, it is considered that the electric resistance Rw of the magnetic wire changes due to the skin effect at the same time as the internal inductance Li of the magnetic wire changes. That is, when the skin effect is strong (f> 200 KHZ in the solid line of FIG. 5), the impedance Z is given by δ, where a is the skin thickness, and a is the diameter of the magnetic wire.
【００２４】[0024]
【数１】 [Equation 1]
【００２５】となり、Then,
【００２６】[0026]
【数２】 [Equation 2]
【００２７】（μ0 ：円周透磁率）となるのでＨｅｘで
μ0 が減少し、｜Ｚ｜が大幅に減少する。実施例４ この発明の磁気インピーダンス素子を磁界センサに用い
た。図９はＭＩ素子・ＦＥＴ組合せによる共振型マルチ
バイブレータの例である。この共振型マルチバイブレー
タにおいては、３０μｍ径１mm長の微細なアモルファス
磁性線を用いて、２２０ＭＨｚの自己発振を生じさせる
ことができ、±２（Oe）までの外部印加磁界において、
直線性の良好な磁界検出特性を得ることができた。共振
は磁性線のインダクタンスとＦＥＴのソース・ドレイン
間の内部キャパシタンスで生じている。この共振型マル
チバイブレータにおいては、消費電力は非常に小さく８
ｍＷであった。Since (μ 0 : circumferential magnetic permeability), μ 0 decreases with Hex, and | Z | significantly decreases. Example 4 The magnetic impedance element of the present invention was used for a magnetic field sensor. FIG. 9 shows an example of a resonance type multivibrator using a combination of MI element and FET. In this resonance type multivibrator, a fine amorphous magnetic wire with a diameter of 30 μm and a length of 1 mm can be used to generate self-oscillation of 220 MHz, and in an externally applied magnetic field of up to ± 2 (Oe),
It was possible to obtain magnetic field detection characteristics with good linearity. The resonance is caused by the inductance of the magnetic wire and the internal capacitance between the source and drain of the FET. In this resonance type multivibrator, the power consumption is very small.
It was mW.
【００２８】このＭＩ素子・ＦＥＴ組合せによる共振型
マルチバイブレータの基本的な構造となるＭＩ素子の特
性は、例えば、図１０に示した通りとなる。このＭＩ素
子は２個のＭＩ素子に互いに逆のバイアス直流磁界Ｈb
を印加して、各々のｅW の差が外部印加磁界Ｈexに正比
例する。図１１は図７の自己発振回路のＭＩ素子にはＨ
b を印加せず、１個のＭＩ素子の先端のみをフロッピー
ディスク駆動スピンドルモータのロータリエンコーダ用
３０mm径５１２極着磁のリング磁石表面０．５mmの位置
に置いた場合の磁極磁界検出結果である。この場合磁極
間隔は１５０μｍであった。磁気抵抗素子を用いた場合
の数倍のギャップマージンで明瞭な磁極磁界が検出され
た。The characteristics of the MI element, which is the basic structure of the resonance type multivibrator by this MI element / FET combination, are as shown in FIG. 10, for example. This MI device has two biased DC magnetic fields Hb
Is applied, and the difference in each eW is directly proportional to the externally applied magnetic field Hex. FIG. 11 shows that the MI element of the self-oscillation circuit of FIG.
It is the magnetic pole magnetic field detection result when b is not applied and only the tip of one MI element is placed at the position of the ring magnet surface of the 30 mm diameter 512 pole magnetized ring magnet for the rotary encoder of the floppy disk drive spindle motor. . In this case, the magnetic pole spacing was 150 μm. A clear magnetic pole magnetic field was detected with a gap margin several times that when a magnetoresistive element was used.
【００２９】[0029]
【発明の効果】以上詳しく説明した通り、この発明によ
って、通電電流を高周波化させることによって、ブリッ
ジ回路を用いる必要がなくなり、数ガウスの磁界で５０
％以上のインピーダンス変化を得る非常に感度のよい小
型の磁気インピーダンス効果素子が提供される。さらに
このインピーダンス効果素子を用いることによって、非
常に感度がよく小型の磁気ヘッドが提供される。As described above in detail, according to the present invention, by making the energizing current have a high frequency, it becomes unnecessary to use a bridge circuit, and a magnetic field of several Gauss can be applied.
Provided is a very sensitive and compact magneto-impedance effect element that obtains an impedance change of more than%. Further, by using this impedance effect element, a magnetic head having a very high sensitivity and a small size can be provided.
【００３０】この発明の磁気インピーダンス効果素子を
例えば磁界センサに用いた場合、従来のホール素子の感
度を約１００倍向上させることが可能であり、さらに、
ヘッドの使用温度は従来のホール素子の場合が７０℃程
度で破壊されるのに対して、約２００℃まで増大するこ
とが可能となる。 またさらに、この発明の磁気インピ
ーダンス効果素子をロータリエンコーダヘッドに用いる
と、従来のＭＲ素子に対して約１００倍以上の高感度を
実現し、ヘッドと磁石表面のギャップを０．５mm程度に
離すことができ、ごみの侵入による故障事故などをこと
が可能となる。この発明の磁気インピーダンス効果素子
を用いれば非常に小型の地磁気利用電子方位素子やマイ
クロマシン用のマイクロ磁気センサ、高感度の磁気探傷
センサアレイ、生体磁気センサなど各種の高感度マイク
ロ磁気センサが可能となる。When the magneto-impedance effect element of the present invention is used in, for example, a magnetic field sensor, it is possible to improve the sensitivity of the conventional Hall element by about 100 times.
The operating temperature of the head can be increased up to about 200 ° C., whereas the conventional Hall element is destroyed at about 70 ° C. Furthermore, when the magneto-impedance effect element of the present invention is used in a rotary encoder head, a high sensitivity of about 100 times or more that of a conventional MR element is realized, and the gap between the head and the magnet surface is separated by about 0.5 mm. It is possible to prevent accidents due to the intrusion of dust. The use of the magneto-impedance effect element of the present invention enables various types of high-sensitivity micro-magnetic sensors such as very small geomagnetically utilizing electronic orientation elements, micro-magnetic sensors for micro-machines, high-sensitivity magnetic flaw detection sensor arrays, and bio-magnetic sensors. .
【図１】従来の磁気インダクタンス素子を示した概略図
である。FIG. 1 is a schematic view showing a conventional magnetic inductance element.
【図２】従来の磁気インダクタンス素子の磁性線を示し
た平面図である。FIG. 2 is a plan view showing a magnetic wire of a conventional magnetic inductance element.
【図３】（ａ）（ｂ）（ｃ）（ｄ）は、各々、従来の磁
気インダクタンス素子を用いた磁気インダクタンスの波
形を示した波形図である。3 (a), (b), (c), and (d) are waveform charts each showing a waveform of a magnetic inductance using a conventional magnetic inductance element.
【図４】この発明の磁気インピーダンス素子を示した概
略図である。FIG. 4 is a schematic diagram showing a magneto-impedance element of the present invention.
【図５】磁性線両端間の電圧と高周波電流の周波数との
関係を示した相関図である。FIG. 5 is a correlation diagram showing the relationship between the voltage across the magnetic wire and the frequency of the high frequency current.
【図６】この発明における出力波形を示す波形図であ
る。FIG. 6 is a waveform diagram showing an output waveform in the present invention.
【図７】磁性線両端間の電圧と外部印加磁界との関係を
示した相関図である。FIG. 7 is a correlation diagram showing the relationship between the voltage across the magnetic wire and the externally applied magnetic field.
【図８】磁性線両端間の電圧の変化率と高周波電流周波
数との関係を示した相関図である。FIG. 8 is a correlation diagram showing the relationship between the rate of change in voltage across the magnetic wire and the high frequency current frequency.
【図９】この発明の磁気インピーダンス素子を磁界セン
サに用いた場合の概略図である。FIG. 9 is a schematic view when the magneto-impedance element of the present invention is used in a magnetic field sensor.
【図１０】この発明の磁気インピーダンス素子を磁界セ
ンサに用いた場合の磁性線両端間の電圧と外部印加磁界
との関係を示した相関図である。FIG. 10 is a correlation diagram showing the relationship between the voltage across the magnetic wire and the externally applied magnetic field when the magnetic impedance element of the present invention is used in a magnetic field sensor.
【図１１】磁極磁界検出結果を示した波形図である。FIG. 11 is a waveform diagram showing a magnetic pole magnetic field detection result.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｈ０１Ｆ 1/153 ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 6 Identification code Internal reference number FI Technical indication H01F 1/153
Claims (4)
ることによって生じる円周磁束の時間変化に対する電圧
を、外部印加磁界によって変化させる磁気素子におい
て、印加電流を時間的に変化する電流を高周波とする磁
気インピーダンス効果素子。1. A magnetic element for changing a voltage with respect to time change of a circumferential magnetic flux generated by applying a time-varying current to a magnetic wire by an externally applied magnetic field, Magneto-impedance effect element with high frequency.
線である磁気インピーダンス効果素子。2. The magneto-impedance effect element according to claim 1, wherein the magnetic wire is an amorphous magnetic wire.
方向に磁化容易方向をもつアモルファス磁性線である磁
気インピーダンス効果素子。3. The magneto-impedance effect element according to claim 2, wherein the amorphous magnetic wire is an amorphous magnetic wire having an easy magnetization direction in a circumferential direction.
が、正磁歪をもつアモルファス磁性線としては長さ方向
に圧縮力、負磁歪をもつアモルファス磁性線としては長
さ方向に張力を印加して熱処理を施したアモルファス磁
性線である磁気インピーダンス効果素子。4. The amorphous magnetic wire according to claim 2 or 3, wherein a compressive force is applied in the length direction as an amorphous magnetic wire having positive magnetostriction, and a tension is applied in the length direction as an amorphous magnetic wire having negative magnetostriction. A magneto-impedance effect element that is a heat-treated amorphous magnetic wire.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32381693A JP3197414B2 (en) | 1993-12-22 | 1993-12-22 | Magnetic impedance effect element |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32381693A JP3197414B2 (en) | 1993-12-22 | 1993-12-22 | Magnetic impedance effect element |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07181239A true JPH07181239A (en) | 1995-07-21 |
| JP3197414B2 JP3197414B2 (en) | 2001-08-13 |
Family
ID=18158926
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|---|---|---|---|
| JP32381693A Expired - Lifetime JP3197414B2 (en) | 1993-12-22 | 1993-12-22 | Magnetic impedance effect element |
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| Country | Link |
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| JP (1) | JP3197414B2 (en) |
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