本発明は、非磁性導体からなる対象物の位置、距離、変位、ずれ、キズ、厚さ、面ブレ、軸振動、表面の凹凸、回転数、速度等を、励磁コイルと磁気インピーダンス素子（以下ＭＩ素子と略す）を用いて検出するセンサに関する。 In the present invention, the position, distance, displacement, deviation, scratch, thickness, surface vibration, axial vibration, surface irregularity, rotation speed, speed, etc. of an object made of a non-magnetic conductor can be measured with an excitation coil and a magnetic impedance element (hereinafter referred to as “impact coil”) The present invention relates to a sensor that detects using an abbreviated MI element.
非磁性導体を検出対象として、位置、距離、変位、ずれ、キズ、厚さ、面ブレ、軸振動表面の凹凸、回転数、速度等を検出するセンサとして渦電流を利用したものが知られている。 Sensors that use eddy currents are known as sensors that detect non-magnetic conductors and detect position, distance, displacement, displacement, scratches, thickness, surface blurring, shaft vibration surface irregularities, rotation speed, speed, etc. Yes.
図３１は従来の渦電流を利用した検出センサ７の概念図である。同図の検出センサ７は空芯コイル９、発振回路１０、増幅器１１、信号処理回路１２から構成されている。同図において符号１は非磁性導体対象物である。この検出センサ７は発振回路１０より、空芯コイル９に交流電流を流し交流磁束８を発生させる。該非磁性導体対象物１の表面とセンサ間の距離が短くなると、交流磁束の一部が非磁性導体対象物の内部に侵入して渦電流を発生し、その渦電流により発生した反磁界が交流磁束８を打ち消し、コイル電圧は低下する。反対に、該非磁性導体対象物１の表面とセンサ間の距離が長くなるとコイル電圧は増加する。そこで、このコイル電圧を信号として増幅器で増幅し、信号処理回路で処理する。 FIG. 31 is a conceptual diagram of a detection sensor 7 using a conventional eddy current. The detection sensor 7 shown in FIG. 1 includes an air-core coil 9, an oscillation circuit 10, an amplifier 11, and a signal processing circuit 12. In the figure, reference numeral 1 denotes a nonmagnetic conductor object. This detection sensor 7 causes an alternating current to flow through the air core coil 9 from the oscillation circuit 10 to generate an alternating magnetic flux 8. When the distance between the surface of the nonmagnetic conductor object 1 and the sensor is shortened, a part of the alternating magnetic flux enters the inside of the nonmagnetic conductor object to generate eddy current, and the demagnetizing field generated by the eddy current is AC. The magnetic flux 8 is canceled, and the coil voltage decreases. Conversely, the coil voltage increases as the distance between the surface of the nonmagnetic conductor object 1 and the sensor increases. Therefore, this coil voltage is amplified as a signal by an amplifier and processed by a signal processing circuit.
しかし、このような回転センサは、例えば、コイル径を１０ｍｍ以下に小型化すると感度が落ち、渦電流の反磁場の強さが急激に低下するため、測定対象物の表面積が小さい場合や測定対象物と励磁コイルとの距離（リフトオフと定義する）がおよそ１ｍｍ以上の場合には測定が困難となる。様々な分野で該センサの小型化の要請がある。例えばアルミニウム製測定対象物の凹凸上下の落差が１ｍｍ以下の測定の場合、径１０ｍｍ以下の励磁コイルを使用して安全を見てリフトオフを１ｍｍ以上の測定が困難となる。このような問題に対しては、コイルの巻き数を増やし、コイル電圧を上げること試られたが、十分な信号を得るに到っていない。However, in such a rotation sensor, for example, when the coil diameter is reduced to 10 mm or less, the sensitivity decreases and the strength of the demagnetizing field of the eddy current rapidly decreases. When the distance between the object and the exciting coil (defined as lift-off) is approximately 1 mm or more, measurement becomes difficult. There is a demand for downsizing of the sensor in various fields. For example, in the case where the height difference between the top and bottom of an object to be measured made of aluminum is 1 mm or less, it is difficult to measure a lift-off of 1 mm or more by using an exciting coil having a diameter of 10 mm or less for safety. For such a problem, an attempt was made to increase the coil voltage by increasing the number of turns of the coil, but a sufficient signal was not obtained.
これに対して、近年、ＭＩ素子が、高感度消費電流が少なく、形状が小さいことから注目され、例えば、車載センサとして車速センサ、位置センサ、高さ測定センサ、ポジションセンサ等、また工場内生産ラインとして各種近接センサ、工場内搬送装置などに使用されているか、又はされつつある（特許文献１）。
しかしながら、ＭＩ素子は基本的に非磁性物質に応答しないために、非磁性導体の測定個所に磁性物質を取り付けるが、あるいは蒸着をして使用する必要がある。一方測定個所の取り付けが不可能な場所や測定環境によっては好ましくはない場合がある。On the other hand, in recent years, MI elements have attracted attention because of their low sensitive current consumption and small shape. For example, vehicle sensors include vehicle speed sensors, position sensors, height measurement sensors, position sensors, etc. It is being used or is being used for various proximity sensors, in-plant transfer devices, etc. as a line (Patent Document 1).
However, since the MI element basically does not respond to a nonmagnetic substance, it is necessary to attach a magnetic substance to a measurement location of a nonmagnetic conductor or to use it by vapor deposition. On the other hand, it may not be preferable depending on the location where the measurement location cannot be attached and the measurement environment.
そこで、位置、距離、変位、ずれ、キズ、厚さ、面ブレ、軸振動、表面の凹凸、回転数、速度等を測定する場合、非磁性導体対象物に磁性物質を取り付けや蒸着することなくそのままの形態で高感度に求められるようにすることが求められている。なお、ＭＩ素子を利用した渦電流センサとしては、金属の欠陥検出を目的としたもの（非特許文献１）や、金属体との距離を検出するものが既に提案されているが感度の点で低いかもしくは不明確である。
特開２００２−１９５８６４号 特開２００３−２７３７１８号 日本応用磁気学会誌、２３、１４５３−１４５６（１９９９） Therefore, when measuring position, distance, displacement, displacement, scratches, thickness, surface vibration, axial vibration, surface irregularities, rotation speed, speed, etc., without attaching or depositing a magnetic substance on the nonmagnetic conductor object There is a demand for high sensitivity in the form as it is. In addition, as an eddy current sensor using an MI element, a sensor for detecting a defect of a metal (Non-Patent Document 1) and a sensor for detecting a distance from a metal body have already been proposed. Low or unclear.
JP 2002-195864 A JP 2003-273718 A Journal of the Japan Society of Applied Magnetics, 23, 1453-1456 (1999)
本発明は、ＭＩ素子を利用したセンサにより、非磁性体対象物の位置、変位、ずれ、キズ、厚さ、面ブレ、軸振動、表面の凹凸、回転数、速度をその非磁性導体対象物に磁性物質を取り付けたり、蒸着したりすることなく、そのままの形態で高感度に求める構成と方法を提供することを目的とする。 According to the present invention, the position, displacement, displacement, scratch, thickness, surface vibration, axial vibration, surface unevenness, rotational speed, and speed of the nonmagnetic object are measured by the sensor using the MI element. It is an object of the present invention to provide a structure and a method that can be obtained with high sensitivity in the form as it is without attaching a magnetic substance or vapor deposition.
上記の目的を達成するため、本発明は、非磁性導体対象物の位置、距離、変位、ずれ、キズ、厚さ、面ブレ、軸振動、表面の凹凸、回転数、速度を検出するセンサであって、非磁性体導体対象物を励磁する励磁コイル、励磁コイルにより非磁性体導体対象物による磁束変化を検出するＭＩ素子、及びＭＩ素子により検出された信号を処理する演算回路を備えた検出センサ７を提供する。 In order to achieve the above object, the present invention is a sensor that detects the position, distance, displacement, displacement, scratch, thickness, surface blur, axial vibration, surface irregularity, rotation speed, and speed of a nonmagnetic conductor object. A detection device comprising an exciting coil for exciting a non-magnetic conductor object, an MI element for detecting a magnetic flux change caused by the non-magnetic conductor object by the exciting coil, and an arithmetic circuit for processing a signal detected by the MI element. A sensor 7 is provided.
本発明の検出センサはＭＩ素子を励磁コイルの内部、または外部に配置し、非磁性導体対象物に発生する渦電流による反磁場の影響を直接的に及び励磁コイルを介して効果的に検出センサ出力信号として利用する方法である。高感度で小型化にすることが実現できる。例えば従来の磁気抵抗素子の感度が１ガウス程度であるのに対して、１０−６ガウス程度の高感度のＭＩ素子を反磁場の影響を効果的に取り出すために励磁コイルの内部または外部に配置して後述するコイル磁場の相互作用を利用して更に感度を高め、演算回路を除いたセンサヘッド部を縦横数ｍｍないしそれ以下の寸法に小型化し、検出精度を向上すると同時に、従来測定不可能であったリフトオフでの測定を可能にすることができる。具体的に説明する。励磁コイル内部または励磁コイル周縁外部に設置されたＭＩ素子は励磁コイル内部または励磁コイル周縁外部の設置位置により出力電圧値は異なる。例１として、非磁性導体対象物の渦電流反磁界の影響を受けない環境下では、コイル長さ方向のおよそ中央で出力電圧値は最小値ピークを示す。この後非磁性導体対象物を励磁コイルに近づけると即ちリフトオフを小さくすると出力電圧値は増加し、さらに近接すると最大値に達する。ここで感度を下式に定義する。
感度（％）＝（出力電圧比の最大値−出力電圧比の最小値）×１００（１）
出力電圧値比の最大値を１とすると、ほぼ１００％の感度が得られる。ただし、出力電圧比の最小値は目的に合わせて該ピークより大きい値を用いてもよい。（１）式は後述する他の構成についても成立する。電流反磁界の影響を例２として、非磁性導体対象物の渦電流反磁場を受ける環境下即ち励磁コイルと非磁性導体対象物が近接した状態にある励磁コイル内でＭＩ素子の位置によって出力電圧が最大値ピークとなる領域（領域１とする）、最小値ピークとなる領域（領域２とする）及び最大値から最小値に変化する過渡領域（領域３とする）の３つの領域が存在する。領域１の場合、非磁性導体対象物と励磁コイルの間隔を広げると、即ちリフトオフを大きくするにつれ出力電圧は小さくなる。（１）式を用いて感度を求めることができる。ただし、出力電圧比の最大値は用途に応じて該ピークより小さい値を用いてもよい。領域２の場合非磁性導体対象物と励磁コイルの間隔を広げると、即ちリフトオフを大きくすると、出力電圧は大きくなる。領域３の場合、リフトオフを大きくすると、出力電圧は一端小さくなるが、次に大きくなり複雑な変位を示す。従って、これらの特性を利用して非磁性体対象物の位置、距離、変位、ずれ、キズ、厚さ、面ブレ、軸振動、表面の凹凸、回転数、速度の計測に使用することができる。In the detection sensor of the present invention, the MI element is disposed inside or outside the excitation coil, and the effect of the demagnetizing field due to the eddy current generated in the nonmagnetic conductor object is detected directly and effectively through the excitation coil. This method is used as an output signal. High sensitivity and downsizing can be realized. For example, while the sensitivity of a conventional magnetoresistive element is about 1 gauss, a highly sensitive MI element of about 10-6 gauss is arranged inside or outside the exciting coil in order to effectively extract the influence of the demagnetizing field. By using the interaction of coil magnetic fields, which will be described later, the sensitivity is further improved, and the sensor head part excluding the arithmetic circuit is downsized to several mm or less in dimensions to improve the detection accuracy, and at the same time, conventional measurement is impossible. It was possible to make the measurement at the lift-off that was. This will be specifically described. The output voltage value of the MI element installed inside the excitation coil or outside the periphery of the excitation coil varies depending on the installation position inside the excitation coil or outside the periphery of the excitation coil. As an example 1, in an environment that is not affected by the eddy current demagnetizing field of the nonmagnetic conductor object, the output voltage value exhibits a minimum value peak at approximately the center in the coil length direction. Thereafter, when the nonmagnetic conductor object is brought closer to the exciting coil, that is, when the lift-off is reduced, the output voltage value is increased, and when the object is further approached, the maximum value is reached. Here, the sensitivity is defined by the following equation.
Sensitivity (%) = (Maximum value of output voltage ratio−Minimum value of output voltage ratio) × 100 (1)
When the maximum value of the output voltage value ratio is 1, a sensitivity of almost 100% can be obtained. However, the minimum value of the output voltage ratio may be larger than the peak according to the purpose. Equation (1) holds true for other configurations described later. As an example of the influence of the current demagnetizing field, the output voltage depends on the position of the MI element in the environment where the nonmagnetic conductor object is subjected to the eddy current demagnetizing field, that is, the excitation coil and the nonmagnetic conductor object are close to each other. There are three regions: a region where the peak is the maximum value (referred to as region 1), a region where the peak is the minimum value (referred to as region 2), and a transient region where the maximum value changes from the minimum value (referred to as region 3) . In the case of region 1, the output voltage decreases as the distance between the nonmagnetic conductor object and the exciting coil is increased, that is, as the lift-off is increased. Sensitivity can be obtained using equation (1). However, the maximum value of the output voltage ratio may be smaller than the peak depending on the application. In the case of region 2, when the distance between the nonmagnetic conductor object and the exciting coil is increased, that is, when the lift-off is increased, the output voltage increases. In the case of the region 3, when the lift-off is increased, the output voltage is once reduced, but is then increased to indicate a complicated displacement. Therefore, these characteristics can be used to measure the position, distance, displacement, displacement, scratch, thickness, surface vibration, axial vibration, surface irregularities, rotation speed, and speed of a non-magnetic object. .
以下、図面を参照しながら、本発明を詳細に説明する。なお、各図中、同一符号は同一又は同等の構成要素を表している。図１は本発明の一実施例の検出センサ概念図である。この検出センサ７は、センサヘッド部１３が励磁コイル２及び、ＭＩ素子３で構成されており、また、回路部が励磁用発振回路１４、ＭＩ素子用発振回路１５、及び保持回路１７と増幅器１１からなる演算回路１８で構成されている。ＭＩ素子３は、その外部磁場感知方向（長手方向）が励磁コイル２の軸に対して垂直に該コイル内部または周縁外部（図は省略）に配置されており、非磁性導体対象物１の面に対して水平となるように配置されて使用される。このように励磁コイル２とＭＩ素子３を配置することにより、リフトオフを大きくした場合の感度の向上を大幅に図ることができる。本発明において、ＭＩ素子３としては例えば、直径２０から３０μｍ、長さ約０．５ｍｍから１．０ｍｍの棒状のアモルハスワイヤを使用する。この他、ＭＩ素子としては、ガラス等の基板に蒸着により形成した薄膜ＭＩ素子を使用してもよく、その場合、薄膜ＭＩ素子の大きさは、例えば、縦１〜３ｍｍ×横２〜４ｍｍ×厚さ０．２〜１．５ｍｍ程度となる。ＭＩ素子の出力電圧はコイルの巻数、コイル形状、コイル電圧により異なるので、相対比、即ち出力電圧比を代わりに用いることによって全ての図を関連づけることができる。 Hereinafter, the present invention will be described in detail with reference to the drawings. In each figure, the same numerals indicate the same or equivalent components. FIG. 1 is a conceptual diagram of a detection sensor according to an embodiment of the present invention. In this detection sensor 7, the sensor head portion 13 is composed of the excitation coil 2 and the MI element 3, and the circuit portion is the excitation oscillation circuit 14, the MI element oscillation circuit 15, the holding circuit 17 and the amplifier 11. It is comprised by the arithmetic circuit 18 which consists of. The MI element 3 has an external magnetic field sensing direction (longitudinal direction) perpendicular to the axis of the exciting coil 2 and is disposed inside the coil or outside the periphery (not shown), and the surface of the nonmagnetic conductor object 1 It is arranged and used so that it may become horizontal. By arranging the exciting coil 2 and the MI element 3 in this way, the sensitivity can be greatly improved when the lift-off is increased. In the present invention, for example, a rod-shaped amorphous wire having a diameter of 20 to 30 μm and a length of about 0.5 to 1.0 mm is used as the MI element 3. In addition, as the MI element, a thin film MI element formed by vapor deposition on a substrate such as glass may be used. In that case, the size of the thin film MI element is, for example, 1 to 3 mm in length × 2 to 4 mm in width. The thickness is about 0.2 to 1.5 mm. Since the output voltage of the MI element varies depending on the number of turns of the coil, the coil shape, and the coil voltage, all figures can be related by using the relative ratio, that is, the output voltage ratio instead.
本発明は非磁性導体対象物、励磁コイルおよびＭＩ素子の配置された構成において、ＭＩ素子の位置に依存して、出力電圧が異なることおよび該位置でのリフトオフ特性が異なることから適切な励磁コイルとＭＩ素子の位置関係を決定し用途に合った検出センサを提供する。
先ず、アルミニウム非磁性導体対象物１、励磁コイル２及びＭＩ素子３の順で構成する図２の位置関係により得られる出力電圧比の特性を図３に示す。この構成の場合、該出力電圧はリフトオフが０ｍｍで最低値を示すが、リフトオフの数値が増大するにつれ増大して１０ｍｍに至るとほぼ飽和する傾向がある。即ち、励磁コイル２がＭＩ素子３よりもアルミニウム非磁性導体対象物１により近距離にある場合、該出力電圧はリフトオフの数値が増大するにつれ増大する。（現象Ｂとする）。According to the present invention, in a configuration in which a nonmagnetic conductor object, an excitation coil, and an MI element are arranged, an output voltage differs depending on the position of the MI element, and lift-off characteristics at the position are different. The detection sensor suitable for the use is provided by determining the positional relationship between the MI element and the MI element.
First, FIG. 3 shows the characteristics of the output voltage ratio obtained by the positional relationship of FIG. 2, which is composed of the aluminum nonmagnetic conductor object 1, the exciting coil 2 and the MI element 3 in this order. In the case of this configuration, the output voltage shows a minimum value when the lift-off is 0 mm, but tends to be saturated when the lift-off value increases and reaches 10 mm. That is, when the exciting coil 2 is closer to the aluminum nonmagnetic conductor object 1 than the MI element 3, the output voltage increases as the lift-off value increases. (Referred to as phenomenon B).
次に、アルミニウム非磁性導体対象物１、ＭＩ素子３及び励磁コイル２の順で構成する図４の位置関係により得られる出力電圧比の特性を図５に示す。該出力電圧はリフトオフが０ｍｍで最高値を示すが、リフトオフの数値が増大するにつれ減少して１０ｍｍに至るとほぼ飽和する傾向がある。即ち、励磁コイル２がＭＩ素子３よりもアルミニウム非磁性導体対象１から遠距離にある場合、該出力電圧はリフトオフの数値が増大するにつれ減少する。（現象Ａとする．）。 Next, FIG. 5 shows the characteristics of the output voltage ratio obtained by the positional relationship of FIG. 4 configured in the order of the aluminum nonmagnetic conductor object 1, the MI element 3, and the exciting coil 2. The output voltage shows a maximum value when the lift-off is 0 mm, but tends to be saturated when the lift-off value increases and decreases to 10 mm. That is, when the exciting coil 2 is farther from the aluminum nonmagnetic conductor object 1 than the MI element 3, the output voltage decreases as the lift-off value increases. (Referred to as phenomenon A).
図６の構成において、ＭＩ素子３を励磁コイル２内部の適切な位置に配置し、現象Ａと現象Ｂのバランスをとることによって高感度の検出センサ７を得ることが可能となる。 In the configuration of FIG. 6, the MI element 3 is disposed at an appropriate position inside the exciting coil 2, and the phenomenon A and the phenomenon B are balanced to obtain the highly sensitive detection sensor 7.
例えば、リフトオフを最大限広げてアルミニウム非磁性導体対象物１からの渦電流反磁界の影響をなくし、ＭＩ素子３をコイル内で移動するか、もしくはＭＩ素子３を固定して励磁コイル２を移動すると出力電圧は位置ごとに変化し最小値が現れることを図７に示す。出力電圧が最小となる該バランスの取れた近辺で励磁コイル２を固定すると、例えば図８に示すリフトオフが減少するにつれ該２つの現象Ａ，Ｂのバランスが崩れるために、出力電圧値が大幅に増加するため高感度センサが可能となる。 For example, the lift-off is maximized to eliminate the influence of the eddy current demagnetizing field from the aluminum nonmagnetic conductor object 1, and the MI element 3 is moved in the coil, or the MI element 3 is fixed and the exciting coil 2 is moved. Then, FIG. 7 shows that the output voltage changes for each position and the minimum value appears. If the exciting coil 2 is fixed in the vicinity of the balanced state where the output voltage is minimized, the balance between the two phenomena A and B is lost as the lift-off shown in FIG. Since it increases, a highly sensitive sensor becomes possible.
例えば、アルミニウム非磁性導体対象物１を励磁コイル２に近接状態とし、ＭＩ素子３を励磁コイル２内で移動すると出力電圧は位置ごとに変化し最大値と最小値が現れることを図９に示す。該出力電圧が最小値を示す位置、即ち、該２つの現象Ａ，Ｂのバランスの取れた状態である該位置近辺でＭＩ素子３を固定して高感度の検出センサ７が作成できる。例えば図１０のリフトオフが増加するにつれアルミニウム非磁性導体対象物１に生じた渦電流の反磁場の影響で該２つの現象Ａ，Ｂのバランスが崩れ、出力電圧値が大幅に変化する高感度検出センサ７となる。 For example, FIG. 9 shows that when the aluminum nonmagnetic conductor object 1 is placed in the proximity of the excitation coil 2 and the MI element 3 is moved within the excitation coil 2, the output voltage changes for each position and the maximum value and minimum value appear. . A highly sensitive detection sensor 7 can be created by fixing the MI element 3 at a position where the output voltage shows a minimum value, that is, in the vicinity of the position where the two phenomena A and B are balanced. For example, as the lift-off in FIG. 10 increases, the sensitivity of the two phenomena A and B is lost due to the influence of the demagnetizing field of the eddy current generated in the aluminum non-magnetic conductor object 1, and the output voltage value changes greatly. It becomes the sensor 7.
該出力電圧が最大値を示す位置、即ち、該２つの現象Ａ，Ｂのバランスの取れていない状態である該位置近辺でＭＩ素子３を固定して高感度の検出センサ７が作成できる。例えば図１１のようにリフトオフが増加するにつれアルミニウム非磁性導体対象物１に生じた渦電流の反磁場の影響で該２つの現象Ａ，Ｂのバランスが整い、出力電圧値が大幅に減少する高感度検出センサ７となる。 A highly sensitive detection sensor 7 can be created by fixing the MI element 3 at a position where the output voltage shows the maximum value, that is, in the vicinity of the position where the two phenomena A and B are not balanced. For example, as shown in FIG. 11, as the lift-off increases, the balance between the two phenomena A and B is achieved by the influence of the demagnetizing field of the eddy current generated in the aluminum nonmagnetic conductor object 1, and the output voltage value is greatly reduced. The sensitivity detection sensor 7 is obtained.
このようにしてアルミニウムを非磁性導体対象物１として異なる出力特性が高感度の３種類の検出センサ７は用途に応じて選択することができる。その際、出力電圧の最小値もしくは最大値の位置は励磁コイル２、ＭＩ素子３の形状、寸法により依存するが、必ず励磁コイル２の内部、もしくは側面近辺に限られる。また、励磁コイル２とＭＩ素子３の位置関係から得られる図７、図９の出力電圧信号から任意の感度の検出センサ７の設定が可能である。 In this manner, the three types of detection sensors 7 having different output characteristics and high sensitivity using aluminum as the non-magnetic conductor object 1 can be selected according to the application. At that time, the position of the minimum value or the maximum value of the output voltage depends on the shape and dimensions of the exciting coil 2 and the MI element 3, but is always limited to the inside of the exciting coil 2 or the vicinity of the side surface. Further, the detection sensor 7 having an arbitrary sensitivity can be set from the output voltage signals in FIGS. 7 and 9 obtained from the positional relationship between the exciting coil 2 and the MI element 3.
これまで、ＭＩ素子３が励磁コイル２内部にあるとき、または励磁コイル側面近辺に配置されているときについて述べてきたが、ここでＭＩ素子３がコイル周縁外部に配置しても感度特性が同じ傾向を持つことを説明する。図１６のようにコイルの周縁外部にＭＩ素子３を配置する本考案もまた性能の高い検出器を提供する。本発明も非磁性導体対象物１、励磁コイル２及びＭＩ素子３の３者が関係する位置構成に基づく出力信号の特異点を効果的に利用した高感度、高精度の検出センサ７を提供する。 Up to now, the case where the MI element 3 is inside the excitation coil 2 or the case where the MI element 3 is arranged near the side surface of the excitation coil has been described. However, even if the MI element 3 is arranged outside the coil periphery, the sensitivity characteristics are the same. Explain that they have a tendency. The present invention in which the MI element 3 is arranged outside the periphery of the coil as shown in FIG. 16 also provides a high-performance detector. The present invention also provides a high-sensitivity and high-precision detection sensor 7 that effectively uses a singular point of an output signal based on a positional configuration in which the nonmagnetic conductor object 1, the exciting coil 2, and the MI element 3 are related. .
図１２、図１４、図１６はアルミニウム非磁性導体対象物１、ＭＩ素子３及び励磁コルとの位置関係と出力電圧を説明するための概念図である。図１２において、アルミニウム非磁性導体対象物１に対向して励磁コイル２、斜め前方に該励磁コイル２が位置するようにＭＩ素子３が配置されている構成の場合、該出力電圧はリフトオフが０ｍｍで最低値を示すが、リフトオフの数値が増大するにつれ増大し、１０ｍｍに至りほぼ飽和する。図２の構成の検出センサ７と同じ傾向があることを図１３が示している。即ち励磁コイル２がＭＩ素子３よりもアルミニウム非磁性導体対象物１により近距離にある場合該出力電圧はリフトオフの数値が増大するにつれ増大する現象Ｂを示す。 FIGS. 12, 14, and 16 are conceptual diagrams for explaining the positional relationship and output voltage between the aluminum nonmagnetic conductor object 1, the MI element 3, and the excitation coll. In FIG. 12, when the MI coil 3 is arranged so that the exciting coil 2 faces the aluminum nonmagnetic conductor object 1 and the exciting coil 2 is positioned obliquely forward, the output voltage has a lift-off of 0 mm. Shows a minimum value, but increases as the lift-off value increases, reaches 10 mm, and is almost saturated. FIG. 13 shows that there is the same tendency as the detection sensor 7 having the configuration of FIG. That is, when the exciting coil 2 is closer to the aluminum nonmagnetic conductor object 1 than the MI element 3, the output voltage shows a phenomenon B that increases as the lift-off value increases.
図１４において、アルミニウ厶非磁性導体対象物１に対向してＭＩ素子３、該ＭＩ素子３の斜め後方に該励磁コイル２が位置する構成の場合、図１５において該出力電圧はリフトオフが０ｍｍで最高値を示すが、リフトオフが増大するにつれ減少して１０ｍｍに至るとほぼ飽和する。この傾向は図４の構成の検出センサ７と同じ傾向があることを示している。即ち、アルミニウム非磁性導体対象物１に対して、励磁コイル２がＭＩ素子３よりも遠距離にある場合、該出力電圧はリフトオフの数値が増大するにつれ減少する全く逆の現象Ａ示す。 In FIG. 14, when the MI element 3 is opposed to the aluminum nonmagnetic conductor object 1 and the exciting coil 2 is positioned obliquely behind the MI element 3, the output voltage in FIG. Although it shows the maximum value, it decreases as the lift-off increases, and is almost saturated when it reaches 10 mm. This tendency indicates the same tendency as that of the detection sensor 7 having the configuration shown in FIG. That is, when the exciting coil 2 is located farther than the MI element 3 with respect to the aluminum nonmagnetic conductor object 1, the output voltage shows a completely opposite phenomenon A that decreases as the lift-off value increases.
図１６はアルミニウム非磁性導体対象物１に対向して励磁コイル２の周縁外部に近接してＭＩ素子３が配置される構成を示している。現象Ａと現象Ｂの影響を受け、励磁コイル２内のＭＩ素子３の出力電圧は設置される位置に依存する。 FIG. 16 shows a configuration in which the MI element 3 is arranged close to the outer periphery of the excitation coil 2 so as to face the aluminum nonmagnetic conductor object 1. Under the influence of the phenomenon A and the phenomenon B, the output voltage of the MI element 3 in the exciting coil 2 depends on the position where it is installed.
ＭＩ素子３もしくは励磁コイル２の間隔を２００ｍｍ以上離した場合、即ちアルミニウム非磁性導体対象物１の渦電流反磁界の影響を無視できる距離において、該励磁コイル２と該ＭＩ素子３の位置関係から生ずる特性について説明する。ＭＩ素子３が非対象物側励磁コイル周縁外部端面から励磁コイル２に沿って反対面の励磁コイル周縁外部に至った後までの過程でＭＩ素子３測定点が該励磁コイル２の周縁外部に沿って移動する図１６のとき、ＭＩ素子３の出力電圧値は下降し、ＭＩ素子３がコイル周縁外部範囲内で最小となることを図１７に示す。この最小値を示す位置では現象Ａ，Ｂが拮抗し、共に打ち消しあってバランスが励磁コイル２内部で保たれているものと考える。リフトオフ距離を狭めると、反磁界の影響が現れ、バランスが崩れ出力電圧が増加して、図１８の高出力電圧変化が得られる。 From the positional relationship between the exciting coil 2 and the MI element 3 when the interval between the MI element 3 or the exciting coil 2 is 200 mm or more, that is, at a distance where the influence of the eddy current demagnetizing field of the aluminum nonmagnetic conductor object 1 can be ignored. The resulting characteristics will be described. The MI element 3 measurement point is along the outer periphery of the excitation coil 2 in the process from when the MI element 3 reaches the outside of the excitation coil periphery on the opposite surface along the excitation coil 2 from the non-object side excitation coil periphery outer end surface. FIG. 17 shows that the output voltage value of the MI element 3 decreases and the MI element 3 becomes the minimum within the coil peripheral outside range. It is considered that the phenomenon A and B antagonize at the position showing the minimum value, cancel each other, and the balance is maintained inside the exciting coil 2. When the lift-off distance is shortened, the influence of the demagnetizing field appears, the balance is lost, the output voltage increases, and the high output voltage change of FIG. 18 is obtained.
非磁性導体対象物１と励磁コイル２間の距離を近接して、ＭＩ素子３が非磁性導対象物側励磁コイル周縁外部端面に近接した位置から、該励磁コイル周縁外部に沿って反対面の近接位置に至るまでの過程で、ＭＩ素子３の位置と出力電圧値の関係を図１９に示す。コイル非磁性導体対象物１側外側からＭＩ素子３が移動するにつれ、出力電圧は増大し、最大値に到達する。この最大値までに至る任意の位置で作成した検出センサ７はリフトオフが大きくなるにつれ出力電圧が低下する図２０の傾向を持ち、この領域を領域１とする。 When the distance between the nonmagnetic conductor object 1 and the exciting coil 2 is close, the MI element 3 is located on the opposite surface along the outer periphery of the exciting coil from the position close to the outer peripheral edge of the nonmagnetic conductive object side exciting coil. FIG. 19 shows the relationship between the position of the MI element 3 and the output voltage value in the process up to the proximity position. As the MI element 3 moves from the outside of the coil nonmagnetic conductor object 1 side, the output voltage increases and reaches the maximum value. The detection sensor 7 created at an arbitrary position up to this maximum value has the tendency shown in FIG. 20 in which the output voltage decreases as the lift-off increases.
更にＭＩ素子３が移動すると出力電圧は最大値から最小値に向かって減少する。この領域を領域３とする。領域３で作成した検出センサ７は図２１のようにリフトオフが大きくなるにつれ出力電圧が減少する現象Ａと増加する現象Ｂが混在する。ＭＩ素子３が移動すると出力電圧は最小値に達する。最小値近辺で作成した検出センサ７はリフトオフが大きくなるにつれ、出力電圧も大きくなる図２２の結果を得る。この領域を領域２とする。更に、ＭＩ素子３が励磁コイル２の反対側の周縁外部端面近辺に至るまで、増加し最大値に達しその後低下する。 Further, when the MI element 3 moves, the output voltage decreases from the maximum value to the minimum value. This region is referred to as region 3. As shown in FIG. 21, the detection sensor 7 created in the region 3 includes a phenomenon A in which the output voltage decreases and a phenomenon B in which the output voltage increases as the lift-off increases. When the MI element 3 moves, the output voltage reaches a minimum value. The detection sensor 7 created near the minimum value obtains the result of FIG. 22 in which the output voltage increases as the lift-off increases. This region is referred to as region 2. Further, the MI element 3 increases until reaching the vicinity of the outer peripheral edge on the opposite side of the exciting coil 2, reaches a maximum value, and then decreases.
検出センサ７の感度調整法について説明する
検出センサ７の感度は非磁性導体対象物１、ＭＩ素子３および励磁コイル２の位置関係から得られる曲線より容易に設定できる。
一例として、ＭＩ素子３もしくは励磁コイル２の間隔を非磁性導体対象物１から２００ｍｍ上離した場合、即ちアルミニウム非磁性導体対象物１の渦電流反磁界の影響を無視できる距離において、非磁性導体対象物側励磁コイル２面の外、励磁コイル２内、非磁性導体対象物側励磁コイル反対面の外の順にＭＩ素子３を移動させながら出力電圧値を測定すると、励磁コイル２内部で、図７のように零に近い最小値を含む曲線が得られる。この出力電圧が最小値を示す位置で励磁コイル２とＭＩ素子３を接着剤で固定し検出センサ７を形成する。ここで検出センサ７とアルミニウム非磁性導体対象物１間のリフトオフを図８に示すように小さくすると、出力電圧信号はおおきくなり、さらにリフトオフが零では最大値となる。具体的に説明すると、信号の初期値、例えばリフトオフが２００ｍｍのとき零に近い値が設定でき、リフトオフが、例えば、０ｍｍのとき、出力電圧は最高値近くに大きくなるために、ほぼ１００パーセントの高感度の信号を得ることができる高感度センサを提供できる。この説明は図６のＭＩ素子３が励磁コイル２の内部にある場合であるが、図１６のようにＭＩ素子３が励磁コイル２の周縁外部にあっても出力電圧の最小値となる位置でＭＩ素子３と励磁コイル２を固定して図１８に示している高感度の検出センサ７を提供することが可能である。The sensitivity of the detection sensor 7 for explaining the sensitivity adjustment method of the detection sensor 7 can be easily set from a curve obtained from the positional relationship between the nonmagnetic conductor object 1, the MI element 3, and the exciting coil 2.
As an example, when the interval between the MI element 3 or the exciting coil 2 is 200 mm above the nonmagnetic conductor object 1, that is, at a distance where the influence of the eddy current demagnetizing field of the aluminum nonmagnetic conductor object 1 can be ignored. When the output voltage value is measured while moving the MI element 3 in the order of outside the object side exciting coil 2 surface, inside the exciting coil 2 and outside the nonmagnetic conductor object side exciting coil, the inside of the exciting coil 2 A curve including a minimum value close to zero, such as 7, is obtained. The excitation coil 2 and the MI element 3 are fixed with an adhesive at a position where the output voltage shows the minimum value, and the detection sensor 7 is formed. Here, when the lift-off between the detection sensor 7 and the aluminum nonmagnetic conductor object 1 is reduced as shown in FIG. 8, the output voltage signal increases, and when the lift-off is zero, the maximum value is obtained. Specifically, the initial value of the signal, for example, a value close to zero can be set when the lift-off is 200 mm, and when the lift-off is, for example, 0 mm, the output voltage becomes close to the maximum value. A highly sensitive sensor capable of obtaining a highly sensitive signal can be provided. This explanation is for the case where the MI element 3 in FIG. 6 is inside the excitation coil 2, but at a position where the minimum value of the output voltage is obtained even if the MI element 3 is outside the periphery of the excitation coil 2 as shown in FIG. The highly sensitive detection sensor 7 shown in FIG. 18 can be provided with the MI element 3 and the excitation coil 2 fixed.
また励磁コイル２に流す電流を調整することで高い出力の得られる検出センサ７を提供できる。なお零点はＭＩ素子３や励磁コイル２の微妙な形状、寸法により励磁コイル２内部で変動するが、上述の電気的手法で零点の位置を見出してＭＩ素子３と励磁コイル２を容易に固定することができる。 Moreover, the detection sensor 7 which can obtain a high output by adjusting the electric current sent through the exciting coil 2 can be provided. The zero point fluctuates inside the excitation coil 2 depending on the delicate shape and dimensions of the MI element 3 and the excitation coil 2, but the MI element 3 and the excitation coil 2 are easily fixed by finding the position of the zero point by the above-described electrical method. be able to.
二例として、ＭＩ素子３もしくは励磁コイル２が磁性導体対象物と間隔が０ｍｍで近接した場合、即ちアルミニウム非磁性導体対象物１の渦電流反磁界の影響を受ける距離において、非磁性導体対象物側励磁コイル２側面、励磁コイル２内、非磁性導体対象物側励磁コイル２反対面の外の順に固定したＭＩ素子３を内在して励磁コイル２を移動させながら出力電圧値を測定した結果を図９に示す。特に図６の範囲で増大、最大値、減少、最小値、再度増大と複雑な変化をする。この出力電圧が最小値を示す位置で励磁コイル２とＭＩ素子３を接着剤で固定し検出センサ７を形成する。ここで検出センサ７とアルミニウム非磁性導体対象物１間のリフトオフを大きくすると、図１０に示すように出力電圧信号は大きくなる。
この説明は図６のＭＩ素子３が励磁コイル２の内部にある場合であるが、図１６のようにＭＩ素子３が励磁コイル２の周縁外部にあっても出力電圧の最小値となる位置でＭＩ素子３と励磁コイル２を固定して作成した検出センサ７を用いて図２２に示すリフトオフの増加に対する出力電圧の増加率の大きい高感度の検出センサ７の提供することが可能である。As an example, when the MI element 3 or the excitation coil 2 is close to the magnetic conductor object with a distance of 0 mm, that is, at a distance affected by the eddy current demagnetizing field of the aluminum nonmagnetic conductor object 1, the nonmagnetic conductor object The result of measuring the output voltage value while moving the excitation coil 2 with the MI element 3 fixed in the order of the side of the side excitation coil 2, the inside of the excitation coil 2, and the outer surface of the non-magnetic conductor object side excitation coil 2. As shown in FIG. In particular, in the range of FIG. 6, there are complicated changes such as increase, maximum value, decrease, minimum value, and increase again. The excitation coil 2 and the MI element 3 are fixed with an adhesive at a position where the output voltage shows the minimum value, and the detection sensor 7 is formed. Here, if the lift-off between the detection sensor 7 and the aluminum nonmagnetic conductor object 1 is increased, the output voltage signal increases as shown in FIG.
This explanation is for the case where the MI element 3 in FIG. 6 is inside the excitation coil 2, but at a position where the minimum value of the output voltage is obtained even if the MI element 3 is outside the periphery of the excitation coil 2 as shown in FIG. It is possible to provide the high-sensitivity detection sensor 7 having a large increase rate of the output voltage with respect to the increase in lift-off shown in FIG. 22 by using the detection sensor 7 formed by fixing the MI element 3 and the excitation coil 2.
次に、図９の出力電圧が最大値を示す位置で励磁コイル２とＭＩ素子３を接着剤で固定し検出センサ７を形成する。図１１に示すリフトオフの増加に対する出力電圧を測定し、減少率の大きい高感度の検出センサ７の提供することが可能である。
この説明は図６のＭＩ素子３が励磁コイル２の内部にある場合であるが、図１６のようにＭＩ素子３が励磁コイル２の周縁外部にあっても出力電圧の最大値となる位置でＭＩ素子３と励磁コイル２を固定して作成したセンサヘッドを用いて図２０に示すリフトオフの増加対する出力電圧の減少率の大きい高感度の検出センサ７の提供することが可能である。Next, the excitation coil 2 and the MI element 3 are fixed with an adhesive at a position where the output voltage of FIG. It is possible to measure the output voltage with respect to the increase in lift-off shown in FIG. 11 and provide the high-sensitivity detection sensor 7 having a large decrease rate.
This explanation is for the case where the MI element 3 in FIG. 6 is inside the exciting coil 2, but at a position where the maximum value of the output voltage is obtained even if the MI element 3 is outside the periphery of the exciting coil 2 as shown in FIG. It is possible to provide a highly sensitive detection sensor 7 having a large output voltage decrease rate with respect to an increase in lift-off shown in FIG. 20 using a sensor head formed by fixing the MI element 3 and the exciting coil 2.
銅、真鍮、ステンレス、鉄などの非磁性導体対象物はアルミニウム非磁性導体対象物と感度が異なるが、出力特性はほぼ同じ傾向であり、例えばリフトオフが増加するにつれ出力電圧値のより高い特性をもつ高感度検出センサが可能となる。また、リフトオフを最大限広げてＭＩ素子３をコイル内で移動し出力電圧が最小となる近辺でＭＩ素子３を固定すると、リフトオフが増加するにつれより出力電圧値のより低くなる特性をもつ高感度検出センサ７が可能となる。 Non-magnetic conductor objects such as copper, brass, stainless steel, and iron have different sensitivities from aluminum non-magnetic conductor objects, but the output characteristics tend to be almost the same.For example, as the lift-off increases, the output voltage value becomes higher. A high-sensitivity detection sensor can be realized. Further, when the MI element 3 is moved in the coil with the lift-off being maximized and the MI element 3 is fixed in the vicinity where the output voltage is minimized, the output voltage value becomes lower as the lift-off increases. The detection sensor 7 becomes possible.
実施例１ Example 1
試−１
励磁コイル２軸線上にＭＩ素子３を配置する図２、図４及び図６の様態からなる検出セサ７であって、高感度、高精度が取得できる確実な感度調整方法について説明する。
ＭＩセンサ３及び励磁コイル２はアルミニウム製非磁性導体対象物１からの渦電流反磁界の影響を受けない距離例えば２００ｍｍ以上の間隔にする。励磁コイル２としては、例えば、線径０．０１ｍｍ〜１ｍｍの銅線からなる、外径４．１４ｍｍ、内径３．０２及び厚み．０．８ｍｍのパンケーキ型励磁コイル２を使用した励磁コイル２には５Ｖｐ−ｐの８０ｋＨｚの周波数交流電圧を加えた測定はコイル内部ばかりでなく、その延長上においても測定した。出力はシンクロスコープで観察した。観察例を図２４，２５．２６に示す。横軸が時間に対して、縦軸は出力電圧である。図２４は出力電圧が１０ｍＶ以下、図２５は出力電圧が約１５０ｍＶ、図２６が約４００ｍＶ出力の各例である。
励磁コイル２がアルミニウム製非磁性導体対象物１に向かってＭＩ素子３の前方にある図２の様態のとき、リフトオフが大きくなるにつれて、出力電圧比は上昇する図３の現象Ｂを示した。励磁コイル２がアルミニウ厶製非磁性導体対象物１に向かってＭＩ素子３の後方にある図４の様態のとき、リフトオフが大きくなるにつれて、出力電圧比は下降する図５の現象Ａを示した。Trial-1
A description will be given of a reliable sensitivity adjustment method for obtaining high sensitivity and high accuracy, which is the detection sensor 7 having the MI elements 3 arranged on the two axes of the exciting coil and having the modes shown in FIGS.
The MI sensor 3 and the excitation coil 2 are set to a distance not affected by the eddy current demagnetizing field from the aluminum nonmagnetic conductor object 1, for example, 200 mm or more. As the exciting coil 2, for example, an outer diameter of 4.14 mm, an inner diameter of 3.02, and a thickness of copper wire having a wire diameter of 0.01 mm to 1 mm are used. The excitation coil 2 using the 0.8 mm pancake-type excitation coil 2 was measured not only in the coil but also on the extension thereof by applying an AC voltage of 80 kHz frequency of 5 Vp-p. The output was observed with a synchroscope. An example of observation is shown in FIGS. The horizontal axis represents time, and the vertical axis represents output voltage. 24 shows an example in which the output voltage is 10 mV or less, FIG. 25 shows each example in which the output voltage is about 150 mV, and FIG. 26 shows about 400 mV output.
When the exciting coil 2 is in front of the MI element 3 toward the aluminum non-magnetic conductor object 1, the output voltage ratio increases as the lift-off increases. In the state of FIG. 4 in which the exciting coil 2 is behind the MI element 3 toward the nonmagnetic conductor object 1 made of aluminum, the phenomenon A in FIG. 5 in which the output voltage ratio decreases as the lift-off increases is shown. .
ＭＩ素子３を励磁コイル２内、外部で出力電圧を測定しながら移動させると、出力電圧は移動につれて下降しほぼ零近くまで到達後再度上昇したことにより励磁コイル２内部で最小値を得ることができた。結果を図７に示す。この最小値を示す位置で励磁コイル２とＭＩ素子３の両方を接着剤または機械的に固定した検出センサ７を成した。図８に検出センサ７を用いて測定したリフトオフと出力電圧比の関係を示す。リフトオフが減少するにつれて出力電圧の増加が大きく、ほぼ１００パーセントの高感度を得ることができた。When the MI element 3 is moved while measuring the output voltage inside and outside the exciting coil 2, the output voltage decreases as it moves, reaches a value close to zero, and then rises again, thereby obtaining a minimum value inside the exciting coil 2. did it. The results are shown in FIG. A detection sensor 7 in which both the exciting coil 2 and the MI element 3 are fixed with an adhesive or mechanically is formed at a position showing the minimum value. FIG. 8 shows the relationship between the lift-off measured using the detection sensor 7 and the output voltage ratio. As the lift-off decreased, the output voltage increased greatly, and a high sensitivity of almost 100 percent could be obtained.
試−２
励磁コイル２軸線上に平行にＭＩ素子３を配置した図２、図４、図６の３様態から構成からなる検出センサ７の高精度、高感度が取得できる第２番目の感度調整方法を説明する。ＭＩ素子３及び励磁コイル２はアルミニウム製非磁性導体対象物１と近接して配置し、積極的にアルミニウム製非磁性導体対象物１の影響を受けるようにした（リフトオフ０ｍｍ）。ＭＩ素子３をアルミニウム製非磁性導体対象物１側から励磁コイル２軸線に平行に順次励磁コイル２内を通って該対象物と反対側に移動させたときの移動距離と出力電圧比の関係を図９に示す。ＭＩ素子３が励磁コイル２内部に存在する図６の様態では、現象Ａと現象Ｂの相互作用がより顕著に現れる領域である。０．８ｍｍ幅の励磁コイル２内部で最大（領域１）と最小（領域２）の二つのピーク値と両ピーク間にまたがる斜線（領域３）が示された。領域１の近辺で形成した検出センサ７はリフトオフの増加に伴う出力電圧比の減少率が大きいことを図１１に示した。Trial-2
A second sensitivity adjustment method capable of acquiring high accuracy and high sensitivity of the detection sensor 7 having the configuration shown in FIGS. 2, 4 and 6 in which the MI element 3 is arranged in parallel on the two axes of the exciting coil will be described. To do. The MI element 3 and the exciting coil 2 are arranged close to the aluminum nonmagnetic conductor object 1 so as to be positively influenced by the aluminum nonmagnetic conductor object 1 (lift-off 0 mm). The relationship between the movement distance and the output voltage ratio when the MI element 3 is moved from the aluminum non-magnetic conductor object 1 side in parallel to the excitation coil 2 axis and sequentially through the excitation coil 2 to the opposite side of the object. As shown in FIG. In the state of FIG. 6 in which the MI element 3 is present inside the exciting coil 2, this is a region where the interaction between the phenomenon A and the phenomenon B appears more prominently. Two peak values (maximum (region 1) and minimum (region 2)) inside the exciting coil 2 having a width of 0.8 mm and a diagonal line (region 3) extending between the two peaks are shown. FIG. 11 shows that the detection sensor 7 formed in the vicinity of the region 1 has a large reduction rate of the output voltage ratio with an increase in lift-off.
領域２の近辺で形成した検出センサ７はリフトオフの増加につれて出力電圧比変化が大きくなることを図１０に示した。 FIG. 10 shows that the change in the output voltage ratio of the detection sensor 7 formed in the vicinity of the region 2 increases as the lift-off increases.
領域３の近辺では励磁コイル２とＭＩ素子３の位置の微小な変化により、リフトオフの増加に伴い出力電圧は一旦減少するが、直ぐに増加するＡ，Ｂの２現象からなる傾向を図２３に示した。
実施例２
試−３In the vicinity of region 3, the output voltage decreases once as lift-off increases due to slight changes in the positions of the exciting coil 2 and the MI element 3, but the tendency consisting of two phenomena A and B immediately increases is shown in FIG. It was.
Example 2
Trial-3
励磁コイル２の周縁外部にＭＩ素子３を配置した図１２、図１４及び図１６の３様態から構成からなる検出センサ７の高精度、高感度が取得できる簡単明瞭な感度調整方法を説明する。ＭＩ素子３及び励磁コイル２はアルミニウム製非磁性導体対象物１からの渦電流反磁界の影響を受けない距離例えば２００ｍｍ以上の間隔にする。励磁コイル２としては、例えば、線径０．０１ｍｍ〜１ｍｍの銅線からなる、外径４．１４ｍｍ、内径３．０２及び厚み１．５ｍｍのパンケーキ型励磁コイル２を使用した。励磁コイル２には５Ｖｐ−ｐの６０ｋＨｚの周波数交流電圧を加えた。測定はコイル内部もしくは該周縁ばかりでなく、その延長上においても測定した。出力はシンクロスコープで観察した。 A simple and clear sensitivity adjustment method capable of obtaining high accuracy and high sensitivity of the detection sensor 7 having the configuration of the three modes of FIGS. 12, 14 and 16 in which the MI element 3 is arranged outside the periphery of the exciting coil 2 will be described. The MI element 3 and the excitation coil 2 are set to a distance not affected by the eddy current demagnetizing field from the aluminum nonmagnetic conductor object 1, for example, 200 mm or more. As the exciting coil 2, for example, a pancake type exciting coil 2 made of a copper wire having a wire diameter of 0.01 mm to 1 mm and having an outer diameter of 4.14 mm, an inner diameter of 3.02 and a thickness of 1.5 mm was used. The excitation coil 2 was applied with a frequency alternating voltage of 60 V and 5 Vp-p. The measurement was performed not only on the inside of the coil or the peripheral edge but also on the extension thereof. The output was observed with a synchroscope.
励磁コイル２がアルミニウム製非磁性導体対象物１に向かってＭＩ素子３の前方にある図１２の様態のとき、リフトオフが大きくなるにつれて、出力電圧比は上昇する図１３の現象Ｂを示した。また励磁コイル２がアルミニウム製非磁性導体対象物１に向かってＭＩ素子３の後方にある図１４の様態のとき、リフトオフが大きくなるにつれて、出力電圧比は下降する図１５の現象Ａを示した。 When the exciting coil 2 is in front of the MI element 3 toward the aluminum non-magnetic conductor object 1, the output voltage ratio increases as the lift-off increases. In addition, when the exciting coil 2 is behind the MI element 3 toward the aluminum non-magnetic conductor object 1, the output voltage ratio decreases as the lift-off increases. .
試−４
ＭＩ素子３が励磁コイル２周縁外部に近接している図１６の様態では、現象Ａと現象Ｂの相互作用がより顕著に現れる領域である。アルミニウム製非磁性導体対象物１と励磁コイル２が近接した条件下において、励磁コイル２の外周部に近接しているＭＩ素子３の各位置の出力電圧値を測定した。結果を図１９に示す。１．５ｍｍ幅の励磁コイル外部周縁で最大値（領域１）と最小値（領域２）の二つのピーク値と両ピーク間にまたがる斜線（領域３）が示されている。Trial-4
In the state of FIG. 16 in which the MI element 3 is close to the outside of the periphery of the exciting coil 2, this is a region where the interaction between the phenomenon A and the phenomenon B appears more prominently. Under the condition where the aluminum nonmagnetic conductor object 1 and the exciting coil 2 are close to each other, the output voltage value at each position of the MI element 3 close to the outer peripheral portion of the exciting coil 2 was measured. The results are shown in FIG. Two peak values of the maximum value (region 1) and the minimum value (region 2) and a diagonal line (region 3) extending between the two peaks are shown at the outer periphery of the 1.5 mm wide excitation coil.
領域１で励磁コイル２周縁外部とＭＩ素子３を固定した構成からなる検出センサ７のリフトオフと出力電圧の関係を図２０に示す。リフトオフが大きくなるにつれて非磁性導体対象物１上の渦電流による反磁界の影響が減少し、出力電圧値は最大値から順次低い値に移行した。FIG. 20 shows the relationship between the lift-off and the output voltage of the detection sensor 7 having a configuration in which the MI coil 3 is fixed to the outside of the periphery of the exciting coil 2 in the region 1. As the lift-off increased, the influence of the demagnetizing field due to the eddy current on the non-magnetic conductor object 1 decreased, and the output voltage value gradually shifted from the maximum value to a lower value.
領域１と領域２の中間に存在する斜線の領域３におけるリフトオフと出力電圧の関係を図２１に示す。リフトオフが小さいとき、出力電圧は減少するが、リフトオフが大きくなるにつれ出力電圧は逆転して大きくなる。この領域３では現象Ａと現象Ｂが複雑に絡み合っている。ただし、リフトオフが小さい範囲に限定すれば、感度を高く取ることができるので１ｍｍから１μｍの変量を測定用として適していた。 FIG. 21 shows the relationship between the lift-off and the output voltage in the hatched region 3 existing between the region 1 and the region 2. When the lift-off is small, the output voltage decreases. However, as the lift-off increases, the output voltage reverses and increases. In this region 3, phenomenon A and phenomenon B are intertwined in a complicated manner. However, if the lift-off is limited to a small range, the sensitivity can be increased, so that a variable of 1 mm to 1 μm is suitable for measurement.
領域２で磁コイル２周縁外部とＭＩ素子３を固定した構成からなる検出センサ７のリフトオフと出力電圧の関係を図２２に示す。リフトオフが大きくなるにつれて非磁性導体対象物１上の渦電流による反磁界の影響が減少し、出力電圧値は最小値から順次高い値に移行した。
実施例３FIG. 22 shows the relationship between the lift-off of the detection sensor 7 having a configuration in which the MI element 3 is fixed to the outside of the periphery of the magnetic coil 2 in the region 2 and the output voltage. As the lift-off increased, the influence of the demagnetizing field due to the eddy current on the nonmagnetic conductor object 1 decreased, and the output voltage value shifted from the minimum value to the higher value sequentially.
Example 3
試−５
真鍮を非磁性導体対象物１とした場合の励磁コイル２内の軸線に平行にＭＩ素子３を配置する図６の様態からなる検出センサ７であって、高感度、高精度が取得できる確実な感度調整方法について説明する。ＭＩセンサ３及び励磁コイル２は真鍮製非磁性導体対象物１からの渦電流反磁界の影響を受けない距離例えば２００ｍｍ以上の間隔にした。ＭＩ素子３を励磁コイル２内部で出力電圧を測定しながら真鍮製非磁性導体対象物１側の励磁コイル２側面から移動させると、出力電圧はＭＩ素子３の移動につれて下降しほぼ零近くまで到達後再度上昇したことにより最小値を得ることができた。この最小値を示す位置で励磁コイル２とＭＩ素子３の両方を接着剤または機械的に固定した検出センサ７を作成した。この検出センサ７を用いて図２７にリフトオフと電圧出力値の関係を示す。アルミニウム同等の高い感度である。
試−６Trial-5
The detection sensor 7 having the mode shown in FIG. 6 in which the MI element 3 is arranged in parallel to the axis in the exciting coil 2 when brass is used as the nonmagnetic conductor object 1, and can be obtained with high sensitivity and high accuracy. A sensitivity adjustment method will be described. The MI sensor 3 and the exciting coil 2 were set to a distance not affected by the eddy current demagnetizing field from the brass nonmagnetic conductor object 1, for example, 200 mm or more. When the MI element 3 is moved from the side of the exciting coil 2 on the brass non-magnetic conductor object 1 side while measuring the output voltage inside the exciting coil 2, the output voltage decreases as the MI element 3 moves and reaches nearly zero. The minimum value could be obtained by raising again later. A detection sensor 7 in which both the exciting coil 2 and the MI element 3 were fixed with an adhesive or mechanically at a position showing the minimum value was prepared. FIG. 27 shows the relationship between the lift-off and the voltage output value using this detection sensor 7. High sensitivity equivalent to aluminum.
Trial-6
真鍮を非磁性導体対象物１とした場合の励磁コイル２軸線上に沿ってＭＩ素子３を配置する図６の様態からなる検出センサ７であって、高感度、高精度が取得できる第２の確実な感度調整方法について説明する。ＭＩセンサ３及び励磁コイル２は真鍮製非磁性導体対象物１からの渦電流反磁界の影響を積極的に受けるように近接して配置した。出力電圧はＭＩ素子３の移動につれ最大値と最小値が見つかるが、最小値でＭＩセンサ３と励磁コイル２を固定して検出センサ７を作成した。この検出センサ７を用いて図２８にリフトオフと電圧出力値の関係を示す。アルミニウム同等の高い感度である。
実施例４A detection sensor 7 having the form of FIG. 6 in which the MI element 3 is arranged along the axis of the exciting coil 2 when brass is used as the nonmagnetic conductor object 1, and is a second sensor that can acquire high sensitivity and high accuracy. A reliable sensitivity adjustment method will be described. The MI sensor 3 and the exciting coil 2 were arranged close to each other so as to be positively affected by the eddy current demagnetizing field from the brass nonmagnetic conductor object 1. As the output voltage, the maximum value and the minimum value are found as the MI element 3 moves, and the detection sensor 7 is created by fixing the MI sensor 3 and the excitation coil 2 at the minimum value. FIG. 28 shows the relationship between lift-off and voltage output value using this detection sensor 7. High sensitivity equivalent to aluminum.
Example 4
ステンレスを非磁性導体対象物１とした場合の励磁コイル２軸線上にＭＩ素子３を配置する図６の様態からなる検出センサ７であって、高感度、高精度が取得できる確実な感度調整方法について説明する。ＭＩセンサ３及び励磁コイル２はステンレス製非磁性導体対象物１からの渦電流反磁界の影響を受けない距離例えば２００ｍｍ以上の間隔にした。ＭＩ素子３を励磁コイル２内部で出力電圧を測定しながらステンレス製非磁性導体対象物１側の励磁コイル２側面から移動させると、出力電圧はＭＩ素子３の移動につれて下降しほぼ２０ｍＶまで到達後、励磁コイル２とＭＩ素子３の両方を接着剤または機械的に固定した検出センサ７を作成した。この検出センサ７を用いて図２９にリフトオフと電圧出力値の関係を示す。
実施例５6 is a detection sensor 7 configured as shown in FIG. 6 in which the MI element 3 is arranged on the axis of the exciting coil 2 when stainless steel is used as the nonmagnetic conductor object 1, and a reliable sensitivity adjustment method capable of obtaining high sensitivity and high accuracy. Will be described. The MI sensor 3 and the exciting coil 2 were set to a distance not affected by the eddy current demagnetizing field from the stainless nonmagnetic conductor object 1, for example, 200 mm or more. When the MI element 3 is moved from the side of the exciting coil 2 on the stainless steel nonmagnetic conductor object 1 side while measuring the output voltage inside the exciting coil 2, the output voltage decreases as the MI element 3 moves and reaches approximately 20 mV. Then, a detection sensor 7 in which both the exciting coil 2 and the MI element 3 were fixed with an adhesive or mechanically was prepared. FIG. 29 shows the relationship between lift-off and voltage output value using this detection sensor 7.
Example 5
鉄を非磁性導体対象物１とした場合の励磁コイル２軸線上にＭＩ素子３を配置する図６の様態からなる検出センサ７であって、高感度、高精度が取得できる確実な感度調整方法について説明する。ＭＩ素子３及び励磁コイル２は鉄製非磁性導体対象物１からの渦電流反磁界の影響を受けない距離例えば２００ｍｍ以上の間隔にした。ＭＩ素子３を励磁コイル２内部で出力電圧を測定しながら鉄製非磁性導体対象物１側の励磁コイル２側面から移動させると、出力電圧はＭＩ素子の移動につれて下降しほぼ１０ｍＶまで到達後、励磁コイル２とＭＩ素子３の両方を接着剤または機械的に固定した検出センサ７を作成した。この検出センサ７を用いて図３０にリフトオフと電圧出力値の関係を示す。6 is a detection sensor 7 configured as shown in FIG. 6 in which the MI element 3 is arranged on the two axes of the exciting coil when iron is used as the nonmagnetic conductor object 1, and a reliable sensitivity adjustment method capable of obtaining high sensitivity and high accuracy. Will be described. The MI element 3 and the exciting coil 2 are set to a distance that is not affected by the eddy current demagnetizing field from the iron nonmagnetic conductor object 1, for example, 200 mm or more. When the MI element 3 is moved from the side of the exciting coil 2 on the iron non-magnetic conductor object 1 side while measuring the output voltage inside the exciting coil 2, the output voltage decreases as the MI element moves and reaches approximately 10 mV, and then the exciting voltage is increased. A detection sensor 7 in which both the coil 2 and the MI element 3 were fixed with an adhesive or mechanically was prepared. FIG. 30 shows the relationship between the lift-off and the voltage output value using this detection sensor 7.
本発明の検出センサの基本概念図 Basic conceptual diagram of the detection sensor of the present invention
非磁性導体対象物、励磁コイル、ＭＩ素子の順でコイル軸上に配置した検出センサの構成概念図 Conceptual diagram of the configuration of the detection sensor placed on the coil axis in the order of non-magnetic conductor object, exciting coil, MI element
非磁性導体対象物、励磁コイル、ＭＩ素子の順でコイル軸上に配置した検センサのリフトオフ−出力電圧図 Non-magnetic conductor object, exciting coil, MI element in order of lift-off output voltage diagram of the sensor arranged on the coil axis
非磁性導体対象物、ＭＩ素子、励磁コイルの順でコイル軸上に配置した検センサの構成概念図 Non-magnetic conductor object, MI element, excitation conceptual diagram of the sensor arranged on the coil axis in this order
非磁性導体対象物、ＭＩ素子、励磁コイルの順で一列に配置した検出セサのリフトオフー出力電圧図 Lift-off output voltage diagram of detection sensor arranged in a line in the order of non-magnetic conductor object, MI element, excitation coil
ＭＩ素子を励磁コイル内部に配置した検出センサの構成概念図 Configuration conceptual diagram of detection sensor with MI element placed inside excitation coil
図６において、非磁性導体対象物の渦電流反磁界の影響を無視できる距離であって、励磁コイルとＭＩ素子の位置関係による出力電圧の依存性 In FIG. 6, it is a distance where the influence of the eddy current demagnetizing field of the nonmagnetic conductor object can be ignored, and the dependence of the output voltage on the positional relationship between the exciting coil and the MI element.
図６において、非磁性導体対象物の渦電流反磁界の影響を無視できる距離であって、出力電圧が励磁コイル内で最小値を示す位置にＭＩ素子を固定した検出センサのリトオフー出力電圧図 In FIG. 6, a litho-off output voltage diagram of a detection sensor in which the MI element is fixed at a position where the influence of the eddy current demagnetizing field of the non-magnetic conductor object can be ignored and the output voltage shows the minimum value in the exciting coil.
図６において、非磁性導体対象物が励磁コイルに近接した状態であって励磁コイルとＭＩ素子の位置関係による出力電圧の依存性 In FIG. 6, the output voltage depends on the positional relationship between the exciting coil and the MI element when the nonmagnetic conductor object is close to the exciting coil.
図６おいて、非磁性導体対象物が励磁コイルに近接した状態であって、出力電圧が励磁コイル内で最小値を示す位置にＭＩ素子を固定した検出センサのリフトオフー出力電圧図 In FIG. 6, the lift-off output voltage diagram of the detection sensor in which the MI element is fixed at a position where the nonmagnetic conductor object is close to the exciting coil and the output voltage shows the minimum value in the exciting coil.
図６おいて、非磁性導体対象物が励磁コイルに近接した状態であって、出電圧が励磁コイル内で最大値を示す位置にＭＩ素子を固定した検出センサリフトオフー出力電圧図 In FIG. 6, a detection sensor lift-off output voltage diagram in which the MI element is fixed at a position where the non-magnetic conductor object is close to the excitation coil and the output voltage shows the maximum value in the excitation coil.
非磁性導体対象物に対向した励磁コイルの斜めした後方にＭＩ素子を配置した検出センサの概念図 Conceptual diagram of a detection sensor in which an MI element is arranged obliquely behind an exciting coil facing a non-magnetic conductor object
非磁性導体対象物に対向した励磁コイルの斜めした後方にＭＩ素子を配置した検出センサのリフトオフー出力電圧図 Lift-off output voltage diagram of detection sensor with MI element placed diagonally behind exciting coil facing non-magnetic conductor object
非磁性導体対象物に対向したＭＩ素子の斜め後方に励磁コイルを配置した検出センサの概念図 Conceptual diagram of a detection sensor in which an exciting coil is disposed obliquely behind an MI element facing a nonmagnetic conductor object
非磁性導体対象物に対向したＭＩ素子の斜め後方に励磁コイルを配置した検出センサのリフトオフー出力電圧図 Lift-off output voltage diagram of detection sensor with exciting coil placed diagonally behind MI element facing non-magnetic conductor object
ＭＩ素子を励磁コイル周縁外部に配置した検出センサの構成概念図 Configuration conceptual diagram of detection sensor with MI element arranged outside the excitation coil periphery
図１６のＭＩ素子を励磁コイル周縁外部に配置した検出センサにおいて、非磁性導体対象物の渦電流反磁界の影響を無視できる距離であって、励磁コイルとＭＩ素子の位置関係による出力電圧の依存性 In the detection sensor in which the MI element shown in FIG. 16 is arranged outside the periphery of the exciting coil, the distance is such that the influence of the eddy current demagnetizing field of the nonmagnetic conductor object can be ignored, and the output voltage depends on the positional relationship between the exciting coil and the MI element. sex
図１６のＭＩ素子を励磁コイル周縁外部に配置した検出センサにおいて、非磁性導体対象物の渦電流反磁界の影響を無視できる距離であって、励磁コイル内とＭＩ素子を最小出力電圧で固定して作成したセンサのリフトオフー出力電圧図 In the detection sensor in which the MI element shown in FIG. 16 is arranged outside the periphery of the exciting coil, the distance between the nonmagnetic conductor object and the eddy current demagnetizing field is negligible, and the inside of the exciting coil and the MI element are fixed at the minimum output voltage. Lift-off output voltage diagram of sensor created
図１６のＭＩ素子を励磁コイル周縁外部に配置した検出センサにおいて、非磁性導体対象物が励磁コイルに近接した状態であって、励磁コイルとＭＩ素子の位置関係による出力電圧の依存性 In the detection sensor in which the MI element shown in FIG. 16 is arranged outside the periphery of the excitation coil, the nonmagnetic conductor object is close to the excitation coil and the output voltage depends on the positional relationship between the excitation coil and the MI element.
図１６のＭＩ素子を励磁コイル周縁外部に配置した検出センサにおいて非磁性導体対象物が励磁コイルに近接した状態であって、出電圧が励磁イル内で最大値を示す位置にＭＩ素子を固定した検出センサのリフトオフー出力電圧図 In the detection sensor in which the MI element shown in FIG. 16 is arranged outside the periphery of the exciting coil, the MI element is fixed at a position where the nonmagnetic conductor object is close to the exciting coil and the output voltage shows the maximum value in the exciting coil. Detection sensor lift-off output voltage diagram
図１６のＭＩ素子を励磁コイル周縁外部に配置した検出センサにおいて非磁性導体対象物が励磁コイルに近接した状態であって、検出電圧が励磁コイル内で最大値から最小値に移行する過程の位置でＭＩ素子を固定した検出センサのリフトオフー出力電圧図 In the detection sensor in which the MI element shown in FIG. 16 is arranged outside the periphery of the excitation coil, the nonmagnetic conductor object is close to the excitation coil, and the position of the process in which the detection voltage shifts from the maximum value to the minimum value in the excitation coil Figure of lift-off output voltage of detection sensor with fixed MI element
図１６のＭＩ素子を励磁コイル周縁外部に配置した検出センサにおいて非磁性導体対象物が励磁コイルに近接した状態であって、出力電圧が励磁イル内で最小値を示す位置にＭＩ素子を固定した検出センサリフトオフー出力電圧図 In the detection sensor in which the MI element of FIG. 16 is arranged outside the periphery of the excitation coil, the MI element is fixed at a position where the nonmagnetic conductor object is close to the excitation coil and the output voltage shows the minimum value in the excitation coil. Detection sensor lift-off output voltage diagram
図６のＭＩ素子を励磁コイル内部に配置した検出センサにおいて非磁性導体対象物が励磁コイルに近接した状態であって、出力電圧が励磁コイル内で最大値から最小値に移行する過程の位置でＭＩ素子を固定した検出センサのリフトオフー出力電圧図 In the detection sensor in which the MI element shown in FIG. 6 is arranged inside the exciting coil, the non-magnetic conductor object is close to the exciting coil, and the position where the output voltage shifts from the maximum value to the minimum value in the exciting coil. Lift-off output voltage diagram of detection sensor with fixed MI element
図６のＭＩ素子を励磁コイル内部に配置した検出センサのオシロスコープによる出力電圧波形例 １０ｍＶ以下 Example of output voltage waveform by oscilloscope of detection sensor in which MI element of Fig. 6 is arranged inside exciting coil 10mV or less
図６のＭＩ素子を励磁コイル内部に配置した検出センサのオシロスコープによる出力電圧波形例 約 １５０ｍＶ Example of output voltage waveform by oscilloscope of detection sensor in which MI element of Fig. 6 is arranged inside exciting coil About 150mV
図６のＭＩ素子を励磁コイル内部に配置した検出センサのオシロスコープによる出力電圧波形例 約 ４００ｍＶ Example of output voltage waveform using an oscilloscope of a detection sensor in which the MI element shown in FIG.
非磁性導体対象物を真鍮とし、図６のＭＩ素子を励磁コイル内部に配置した検出センサの構成において、非磁性導体対象物の渦電流反磁界の影響を受けない距離で、励磁コイル内の出力電圧が最小となる位置でＭＩ素子を固定して作成した検出センサのリフトオフー出力電圧図 In the configuration of the detection sensor in which the nonmagnetic conductor object is brass and the MI element of FIG. 6 is arranged inside the excitation coil, the output in the excitation coil is at a distance not affected by the eddy current demagnetizing field of the nonmagnetic conductor object. Lift-off output voltage diagram of the detection sensor created by fixing the MI element at the position where the voltage is minimum
非磁性導体対象物を真鍮とし、図６のＭＩ素子を励磁コイル内部に配置した検出センサの構成において、非磁性導体対象物に近接して、励磁コイル内の出力電圧が最大となる位置でＭＩ素子を固定して作成した検出センサのリフトオフー出力電圧図 In the configuration of the detection sensor in which the nonmagnetic conductor object is brass and the MI element shown in FIG. 6 is arranged inside the excitation coil, the MI is located near the nonmagnetic conductor object and at the position where the output voltage in the excitation coil becomes maximum. Lift-off output voltage diagram of detection sensor created with fixed elements
非磁性導体対象物をステンレスとし、図６のＭＩ素子を励磁コイル内部に配置した検出センサの構成において、非磁性導体対象物の渦電流反磁界の影響を受けない距離で、励磁コイル内の出力電圧が最小となる位置でＭＩ素子を固定して作成した検出センサのリフトオフー出力電圧図 In the configuration of the detection sensor in which the nonmagnetic conductor object is made of stainless steel and the MI element of FIG. 6 is arranged inside the excitation coil, the output in the excitation coil is at a distance not affected by the eddy current demagnetizing field of the nonmagnetic conductor object. Lift-off output voltage diagram of the detection sensor created by fixing the MI element at the position where the voltage is minimum
非磁性導体対象物を鉄とし、図６のＭＩ素子を励磁コイル内部に配置した検出センサの構成において、非磁性導体対象物の渦電流反磁界の影響を受けない距離で、励磁コイル内の出力電圧が最小となる位置でＭＩ素子を固定して作成した検出センサのリフトオフー出力電圧図 In the configuration of the detection sensor in which the nonmagnetic conductor object is iron and the MI element of FIG. 6 is arranged inside the excitation coil, the output in the excitation coil is at a distance not affected by the eddy current demagnetizing field of the nonmagnetic conductor object. Lift-off output voltage diagram of the detection sensor created by fixing the MI element at the position where the voltage is minimum
従来の検出センサ概念図 Conventional detection sensor conceptual diagram
符号の説明Explanation of symbols
１ 非磁性導体対象物
２ 励磁コイル
３ ＭＩ素子
４ 電子回路
５ 回路基板
６ 接続ケーブル
７ 検出センサ
８ 交流磁束
９ 空芯コイル
１０ 発振回路
１１ 増幅器
１２ 信号処理回路
１３ センサヘッド部
１４ 励磁用発振回路
１５ ＭＩ素子用発振回路
１６ 抵抗
１７ 保持回路
１８ 演算回路DESCRIPTION OF SYMBOLS 1 Nonmagnetic conductor object 2 Excitation coil 3 MI element 4 Electronic circuit 5 Circuit board 6 Connection cable 7 Detection sensor 8 AC magnetic flux 9 Air core coil 10 Oscillation circuit 11 Amplifier 12 Signal processing circuit 13 Sensor head part 14 Oscillation circuit 15 for excitation MI element oscillation circuit 16 resistor 17 holding circuit 18 arithmetic circuit
