JPH0723292U - Magnetic gradiometer - Google Patents
Magnetic gradiometerInfo
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- JPH0723292U JPH0723292U JP5795693U JP5795693U JPH0723292U JP H0723292 U JPH0723292 U JP H0723292U JP 5795693 U JP5795693 U JP 5795693U JP 5795693 U JP5795693 U JP 5795693U JP H0723292 U JPH0723292 U JP H0723292U
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Abstract
(57)【要約】
【目的】 １軸、直交２軸、又は直交３軸の磁気検知器
を２個１組用いて磁気検知器を適当距離はなし配置して
２点間の磁気傾度を検出する磁気傾度計に於て、従来に
比べて出力に含まれるノイズの値が小さく製作が容易な
磁気傾度計とする。
【構成】 １方の磁気検知器を基準磁気検知器とし他方
を検出磁気検知器として、基準磁気検知器の検出する地
磁気成分により基準磁気検知器の検出巻線５に負帰還し
て磁気検知素子１ａを零磁界で作動させるとともに、基
準磁気検知器の出力と検出磁気検知器の出力の一部とを
差動にして電圧電流変換回路１４を介し検出磁気検知器
の磁気検知素子１ｂの検出巻線５に入力して零磁界で検
出磁気検知器を作動させるとともに、検出磁気検知器の
増幅度を高め磁気傾度分のみを増幅し検出する。
(57) [Abstract] [Purpose] Detect magnetic gradient between two points by arranging two magnetic detectors each having one axis, two orthogonal axes, or three orthogonal axes and arranging the magnetic detectors at appropriate distances. In the magnetic gradient meter, the value of noise contained in the output is smaller than that of the conventional one and the magnetic gradient meter is easy to manufacture. [Structure] One magnetic detector is used as a reference magnetic detector, and the other magnetic detector is used as a detection magnetic detector, and a magnetic detection element is provided by negatively feeding back to a detection winding 5 of the reference magnetic detector by a geomagnetic component detected by the reference magnetic detector. 1a is operated in a zero magnetic field, and the output of the reference magnetic detector and a part of the output of the detected magnetic detector are made differential, and the detection winding of the magnetic detection element 1b of the detected magnetic detector is made through the voltage-current conversion circuit 14. Input to line 5 to operate the detection magnetic detector at zero magnetic field, increase the amplification degree of the detection magnetic detector and amplify and detect only the magnetic gradient.
Description
【０００１】[0001]
本考案は、地磁気中に強磁性体が存在することによって生ずる磁界によって生 ずる２点間の磁気傾度を検出する磁気傾度計に関するものである。 The present invention relates to a magnetic gradient meter for detecting a magnetic gradient between two points generated by a magnetic field generated by the presence of a ferromagnetic substance in the earth's magnetism.
【０００２】[0002]
従来、この種の磁気傾度計は図２に示すように、２個１組の所謂フラックスゲ ート型磁力計の磁気検知素子１ａ、１ｂ間を離して、又磁気検知素子の方向を同 一方向に揃え、回路の構成が全く同じで検出感度も同じに調整された２個１組の 磁気検知器の各軸（図１は一軸成分のみを示す）の出力を差動増幅器１６に入力 し、その出力を磁気傾度の値として求めていたが、磁気検知素子１ａ、１ｂから の出力信号を夫々独立した２つの回路によって検出しているため、発振ノイズを 低減するため同じ発振回路の出力を用いて磁気検知素子を励磁する等の工夫は行 われていたが、それぞれの成分の出力電圧は差動増幅器の入力で５００００ｎＴ で出力電圧を５Ｖとすると１ｎＴ当りの電圧は０．１ｍＶとなり単位磁界当りの 検出感度が低く差動増幅器１６に入力された後大幅に増幅する必要があり、出力 感度に対する回路ノイズが大きくなること、又磁気検知素子や回路の直線性、又 温度特性の影響が大きく、磁気検知素子が検出した地磁気の値により磁気傾度に 誤差を生ずる原因となる等の問題があった。 2. Description of the Related Art Conventionally, as shown in FIG. 2, a magnetic gradient meter of this type has a magnetic sensing element 1a, 1b of a pair of so-called fluxgate magnetometers separated from each other, and the magnetic sensing elements have the same direction. The outputs of each axis (Fig. 1 shows only one axis component) of a pair of magnetic detectors aligned in the same direction and having the same circuit configuration and the same detection sensitivity are input to the differential amplifier 16. , The output was obtained as the value of the magnetic gradient, but since the output signals from the magnetic sensing elements 1a and 1b are detected by two independent circuits, respectively, the output of the same oscillator circuit is reduced to reduce the oscillation noise. Although the device was used to excite the magnetic sensing element, etc., the output voltage of each component was 50000 nT at the input of the differential amplifier, and if the output voltage was 5 V, the voltage per 1 nT was 0.1 mV. Detection sensitivity per hit is low After the signal is input to the dynamic amplifier 16, it is necessary to amplify it significantly, the circuit noise with respect to the output sensitivity becomes large, the linearity of the magnetic sensing element and the circuit, and the influence of the temperature characteristic are large. There was a problem that the value of the geomagnetism causes an error in the magnetic gradient.
【０００３】[0003]
本考案は、前記の課題を解決するため、一方の磁気検知器を地磁気成分（５０ ０００ｎＴ）を検出する基準磁気検知器にし、基準磁気検知器の地磁気成分の出 力を基準磁気検知器の磁気検出素子に帰還して地磁気成分を打消して零磁界で作 動させるとともに、他方の検出感度を高めて磁気傾度を検出する検出磁気検知器 の磁気検出素子に、基準磁気検知器の出力と検出磁気検知器の出力の一部の電圧 とを検出磁気検知器の磁気検出素子に組合せ入力して、検出磁気検知器の動作範 囲を１００ｎＴ以下の低い磁気傾度の磁界のみを検出するようにして、信号対雑 音比のよい、即ち信号電圧に対して回路ノイズの低い磁気傾度計とするにある。 In order to solve the above problems, the present invention uses one of the magnetic detectors as a reference magnetic detector that detects a geomagnetic component (50,000 nT), and outputs the output of the geomagnetic component of the reference magnetic detector to the magnetic field of the reference magnetic detector. The output of the reference magnetic detector is detected by the magnetic detection element of the detection magnetic detector that returns to the detection element to cancel the geomagnetic component to operate at zero magnetic field and enhance the detection sensitivity of the other to detect the magnetic gradient. The voltage of a part of the output of the magnetic detector is combined and input to the magnetic detecting element of the detecting magnetic detector so that the operating range of the detecting magnetic detector detects only the magnetic field with a low magnetic gradient of 100 nT or less. The magnetic gradient meter has a good signal-to-noise ratio, that is, low circuit noise with respect to the signal voltage.
【０００４】[0004]
本考案は、組となる２個の磁気検知器の内一方の磁気検知器（基準磁気検知器 ）の出力を基準磁気検知器の磁気検知素子に帰還すると共に、基準磁気検知器の 出力電圧と他方の検出磁気検知器の出力電圧の一部とを、共に電圧電流変換回路 を介して他方の検出磁気検知器の入力側の磁気検知素子に帰還して検出磁気検知 器を零磁界で動作させるようにし、検出磁気検知器の出力電圧の増幅度を高めて 、検出磁気検知器の出力電圧により磁気傾度を検出するようにして信号対雑音比 にすぐれた、即ち回路ノイズ低い磁気傾度計を構成する。 The present invention feeds back the output of one magnetic detector (reference magnetic detector) of the two magnetic detectors forming a pair to the magnetic detecting element of the reference magnetic detector and outputs the output voltage of the reference magnetic detector. A part of the output voltage of the other detection magnetic detector is fed back to the magnetic detection element on the input side of the other detection magnetic detector through the voltage-current conversion circuit to operate the detection magnetic detector at zero magnetic field. By increasing the amplification factor of the output voltage of the detection magnetic detector and detecting the magnetic gradient by the output voltage of the detection magnetic detector, a magnetic gradient meter with an excellent signal-to-noise ratio, that is, low circuit noise is constructed. To do.
【０００５】[0005]
従来の磁気傾度計は同じ定数で、検出する方向が同一方を向く磁気検知素子を ２個用いかつ同じ回路構成の２つの磁気検知器を或る距離だけはなして配置し、 夫々の磁気検知器の地磁気の出力（５００００ｎＴ）を差動増幅器に入力してそ の出力の差を求め、更に増幅して必要な電圧にし２つの磁気検知器間の磁気傾度 を検出していたが、本考案の磁気傾度計では定数及び特性の揃った磁気検知素子 を用い、一方の基準磁気検知器で検出した地磁気成分の出力を従来のように基準 磁気検知器の検出巻線に電圧電流変換回路を介し負帰還する一方、他方の検出磁 気検知器の検出巻線に基準磁気検知器の出力を電圧電流変換回路を介して地磁気 成分を打消すように検出磁気検知器の入力の磁気検知素子に検出磁気検知器の出 力の一部と共に負帰還して、検出磁気検知器の磁気検知素子を零磁界で作動する ようにする。他方の検出磁気検知器の出力は、増幅度を高めて２つの磁気検知器 の差のみを増幅するようにする。 The conventional magnetic gradiometer has the same constant, uses two magnetic detectors that detect the same direction, and arranges two magnetic detectors with the same circuit configuration with a certain distance between them. The output of terrestrial magnetism (50000 nT) was input to the differential amplifier, the difference between the outputs was calculated, and further amplified to obtain the required voltage to detect the magnetic gradient between the two magnetic detectors. The magnetic gradient meter uses magnetic sensing elements with uniform constants and characteristics, and the output of the geomagnetic component detected by one of the reference magnetic detectors is negatively applied to the detection winding of the reference magnetic detector via a voltage-current conversion circuit as in the past. On the other hand, the output of the reference magnetic detector is sent to the detection winding of the other detecting magnetic detector through the voltage-current conversion circuit so as to cancel the geomagnetic component. Along with some of the detector output Feedback to, so as to actuate the magnetic detection element of the detected magnetic detector at zero magnetic field. The output of the other magnetic detector is amplified so that only the difference between the two magnetic detectors is amplified.
【０００６】 このような構成としてあるので、従来は２つの磁気検知器の地磁気の値（磁気 検知素子の軸方向が地磁気方向に直交する時は零となり地磁気方向と平行となる 時は国内では最大５００００ｎＴ程の値となる）に対する２つの磁気検知器間の 直線性と温度特性とが一致する必要があること、又２つの磁気検知器の差動入力 の電圧は最大±５００００ｎＴで±５Ｖ程度と１ｎＴ当りの検出電圧は０．１ｍ Ｖと低く、差動増幅器以後の増幅回路で例えば５０ｎＴで５Ｖの出力とすると６ ０ｄＢの増幅度を必要とし、磁気検知器の最低感度を決める回路ノイズが大きく なるのに対し、本考案による磁気傾度計は検出磁気検知器が基準磁気検知器の出 力により検出磁気検知器の地磁気成分の大部分を打消して、２つの磁気検知器の 差の磁気成分のみを増幅すればよく、従来に比べて増幅回路を１段は除くことが 出来、回路ノイズの値は少なくとも本考案の構成とすることにより２０ｄＢは改 善出来る。With such a configuration, conventionally, the value of the geomagnetism of the two magnetic detectors (zero when the axial direction of the magnetic detection element is orthogonal to the geomagnetic direction and the maximum value in Japan when it is parallel to the geomagnetic direction) It is necessary that the linearity and temperature characteristics between the two magnetic detectors (for values of about 50,000 nT) be the same, and the voltage of the differential input of the two magnetic detectors is ± 5V at maximum ± 50000 nT. The detection voltage per 1 nT is as low as 0.1 mV, and if the amplification circuit after the differential amplifier outputs 5 V at 50 nT, for example, an amplification degree of 60 dB is required, and the circuit noise that determines the minimum sensitivity of the magnetic detector is large. On the other hand, in the magnetic gradient meter according to the present invention, the detection magnetic detector cancels out most of the geomagnetic component of the detection magnetic detector by the output of the reference magnetic detector, and the difference between the two magnetic detectors. May be amplified only magnetic component, can be removed in one stage amplification circuit compared to the conventional, 20 dB can improve with the configuration of the values of circuit noise at least present invention.
【０００７】[0007]
本考案の実施例を図面を用い説明する。 図１は本考案の磁気傾度計の実施例を示す回路ブロック図で、１軸成分のみを示 し、実際の磁気傾度計では、図１に示す１軸成分のみで構成した１軸磁気検知器 の磁気検知素子１ａ，１ｂを夫々２組用意し直交して組合せ構成した２軸直交磁 気検知素子を使用した２軸直交磁気検知器、又は同様に、１軸磁気検知器を３組 用意し夫々をＸ軸、Ｙ軸、Ｚ軸方向に直交して組合せた３軸直交磁気検知器等に も適用される。 An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a circuit block diagram showing an embodiment of the magnetic gradient meter of the present invention, showing only a single-axis component, and in an actual magnetic gradient meter, a single-axis magnetic detector composed of only the single-axis component shown in FIG. 2 sets of magnetic detection elements 1a and 1b are prepared, and 2 sets of 2 axis orthogonal magnetic detectors using 2 axis orthogonal magnetic detection elements that are orthogonally combined and configured, or 3 sets of 1 axis magnetic detectors are also prepared. It is also applied to a 3-axis orthogonal magnetic detector, etc., in which the X-axis, Y-axis, and Z-axis directions are combined so as to be orthogonal to each other.
【０００８】 図１において、環状磁芯に励磁巻線と検出巻線とを巻回した磁気検知素子１ａ 、１ｂは、１つの発振回路２の発振出力で励磁回路３を介し励磁巻線４により励 磁され、磁気検知素子の磁芯を励磁し、検出巻線５により地磁気成分が検出され る。地磁気成分は磁芯が地磁気で偏倚されたことによって生ずる検出巻線５に生 ずる非対称波中の倍周波成分を、励磁する交流電圧の周波数の２倍周波成分２ｆ で位相検波回路１０で検波し、地磁気成分に相当する直流電圧を位相検波回路１ ０の出力のコンデンサＣ2及び増幅器Ａ2１１又はＡ4で積分して得る。In FIG. 1, the magnetic sensing elements 1 a and 1 b each having an excitation winding and a detection winding wound around an annular magnetic core are oscillated by one oscillation circuit 2 and are excited by the excitation winding 4 via the excitation circuit 3. When excited, the magnetic core of the magnetic sensing element is excited, and the detection winding 5 detects the geomagnetic component. The geomagnetic component is detected by the phase detection circuit 10 with the double frequency component 2f of the frequency of the AC voltage to be excited, which is the double frequency component in the asymmetrical wave generated in the detection winding 5 caused by the bias of the magnetic core due to the geomagnetism. , The DC voltage corresponding to the geomagnetic component is integrated by the capacitor C 2 of the output of the phase detection circuit 10 and the amplifier A 2 11 or A 4 .
【０００９】 本考案では磁気検知素子１ａの出力Ａは一部は電圧電流変換回路１４を介して 検出巻線５に負帰還し、磁気検知素子１ａの磁芯は常に零磁界で地磁気を検出す るように構成され、磁気検知素子１ａを含む磁気検知器は基準磁気検知器を構成 する。本考案の磁気傾度計では基準磁気検知器の出力Ａの出力を他方の磁気検知 素子１ｂを含む検出磁気検知器に増幅器Ａ5１２と電圧電流変換回路１４を介し 磁気検知素子１ｂの検出巻線５に負帰還し、磁気検知素子１ｂの磁芯を零磁界で 作動するようにする。In the present invention, a part of the output A of the magnetic detection element 1a is negatively fed back to the detection winding 5 via the voltage-current conversion circuit 14, and the magnetic core of the magnetic detection element 1a always detects the earth magnetism with a zero magnetic field. The magnetic detector including the magnetic detecting element 1a constitutes a reference magnetic detector. In the magnetic gradient meter of the present invention, the output of the output A of the reference magnetic detector is connected to the detection magnetic detector including the other magnetic detection element 1b through the amplifier A 5 12 and the voltage-current conversion circuit 14 and the detection winding of the magnetic detection element 1b. Negative feedback is made to 5 so that the magnetic core of the magnetic sensing element 1b is operated at zero magnetic field.
【００１０】 本考案の磁気傾度計では、即ち基準磁気検知器が検出した地磁気検出成分で基 準磁気検知器と検出磁気検知器の地磁気成分を打消すことにより、磁気検知素子 １ｂを含む検出磁気検知器は２つの磁気検知素子間の検出した磁界の差のみを増 幅するので、検出磁気検知器では５０ｎＴないし１００ｎＴ程の地磁気の変化成 分のみを増幅すればよいので、基準磁気検知器が最大５００００ｎＴを最大５Ｖ で出力するのに対し検出磁気検知器では基準磁気検知器と検出磁気検知器の差分 だけ増幅すればよく同じ検出感度のとき同じ磁界で同じ出力電圧にするためには 従来の磁気傾度計では本考案の傾度計に比較して１０００倍ないし５００倍の増 幅度を得るための増幅器が必要となるので、本考案の磁気傾度計では従来に比べ て同じ検出磁界の時には回路ノイズによるノイズの少ない出力電圧が得られる。 即ち、図１の検出巻線５の出力に接続された増幅器Ａ3９の増幅度は図２に示す 従来の磁気傾度計の差動増幅器１６の役割に相当し、従って従来の磁気傾度計と 比較し図２の増幅器Ａ1８、Ａ2１１を必要としないのでそれだけ初段の回路ノイ ズを低減出来る。In the magnetic gradiometer of the present invention, that is, by canceling the geomagnetic components of the reference magnetic detector and the detection magnetic detector with the geomagnetic detection component detected by the reference magnetic detector, the detection magnetic element including the magnetic detection element 1b is detected. Since the detector amplifies only the difference in the detected magnetic field between the two magnetic sensing elements, the detecting magnetic detector only needs to amplify the change component of the geomagnetism of about 50 nT to 100 nT. A maximum of 50000nT is output at a maximum of 5V, whereas the detection magnetic detector needs to amplify only the difference between the reference magnetic detector and the detection magnetic detector. The magnetic gradient meter requires an amplifier to obtain a gain of 1000 to 500 times as compared with the gradient meter of the present invention. When the detection magnetic field is the same, an output voltage with less noise due to circuit noise can be obtained. That is, the amplification factor of the amplifier A 3 9 connected to the output of the detection coil 5 in FIG. 1 corresponds to the role of the differential amplifier 16 of the conventional magnetic gradiometers shown in FIG. 2, thus the conventional magnetic gradiometers does not require an amplifier a 1 8, a 2 11 as compared to Figure 2 can be correspondingly reduced circuit noise of the first stage.
【００１１】 図１において検出磁気検知器の出力Ｂの一部は、基準磁気検知器の出力Ａを検 出磁気検知器の電圧電流変換回路１４に入力する増幅器Ａ5１２の入力側に出力 電圧を分割する帰還可変抵抗Ｒ１７を介し入力され、検出磁気検知器の出力は２ つの磁気検知器が均一磁界中にあるときは検出磁気検知器の出力に接続する帰還 可変抵抗Ｒ１７を調整し出力Ｂの出力電圧を０出力になるよう抵抗Ｒを変え調整 するもであ。以上により、本考案の磁気傾度計を構成する。[0011] portion of the output B of the detected magnetic detector in FIG. 1, reference magnetic detector detect the output A magnetic detector is input to the voltage-current conversion circuit 14 amplifier A 5 12 on the input side to the output voltage Is input via a feedback variable resistor R17 that divides the output of the magnetic field detector. It is also possible to adjust the resistance R so that the output voltage of is 0 output. The magnetic gradient meter of the present invention is constructed as described above.
【００１２】[0012]
本考案の磁気傾度計とすることにより、検出する磁気傾度の検出感度が大きく 、回路ノイズが小さく、製造が容易な磁気傾度計が構成出来ると言う効果を有す る。 The magnetic gradiometer according to the present invention has an effect that a magnetic gradiometer having a high detection sensitivity of a magnetic gradient to be detected, a small circuit noise, and an easily manufactured magnetic gradiometer can be configured.
【図１】図１は、本考案による磁気傾度計を示す回路ブ
ロック図。FIG. 1 is a circuit block diagram showing a magnetic gradient meter according to the present invention.
【図２】図２は、従来の磁気傾度計を示す回路ブロック
図。FIG. 2 is a circuit block diagram showing a conventional magnetic gradient meter.
１ａ、１ｂ 磁気検地素子 ２ 発振回路 ３ 励磁回路 ４ 励磁巻線 ５ 検出巻線 ７ 結合コンデンサ ８、９、１１ 増幅器 １０ 位相検波回路 １２、１６ 差動増幅器 １３ 積分用コンデンサ １４ 電圧電流変換回路 １７ 帰還可変抵抗Ｒ 1a, 1b Magnetic detection element 2 Oscillation circuit 3 Excitation circuit 4 Excitation winding 5 Detection winding 7 Coupling capacitor 8, 9, 11 Amplifier 10 Phase detection circuit 12, 16 Differential amplifier 13 Integration capacitor 14 Voltage current conversion circuit 17 Feedback Variable resistance R
Claims (1)
知器を２個１組用いて２点間の磁気勾配を検出する磁気
傾度計において、検出した地磁気成分の検出電圧を電圧
電流変換回路を介し検出巻線に帰還して地磁気成分を打
消して磁気検知素子を零磁界で作動する一方の磁気検知
器の基準磁気検知器と、及び他方の検出磁気検知器の磁
気検知素子の検出巻線に、前記基準磁気検知器の出力電
圧と他方の検出磁気検知器の出力電圧を可変する手段を
介し接続した差動増幅回路の出力を電圧電流変換回路を
通し入力して検出磁気検知器の地磁気成分を打消し、検
出磁気検知器の出力電圧を増幅して磁気傾度を検出する
ように構成してなることを特徴とする磁気傾度計。1. A magnetic gradiometer for detecting a magnetic gradient between two points by using a pair of one-axis, two-axis orthogonal, or three-axis orthogonal magnetic detectors, and a detected voltage of a detected geomagnetic component is a voltage current. The reference magnetic detector of one magnetic detector that returns to the detection winding through the conversion circuit and cancels the geomagnetic component to operate the magnetic detection element at zero magnetic field, and the magnetic detection element of the other detection magnetic detector The output of a differential amplifier circuit connected to the detection winding through a means for varying the output voltage of the reference magnetic detector and the output voltage of the other detection magnetic detector is input through a voltage-current conversion circuit to detect magnetic detection. A magnetic gradient meter configured to cancel the geomagnetic component of the detector and amplify the output voltage of the detection magnetic detector to detect the magnetic gradient.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5795693U JPH0723292U (en) | 1993-09-29 | 1993-09-29 | Magnetic gradiometer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5795693U JPH0723292U (en) | 1993-09-29 | 1993-09-29 | Magnetic gradiometer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0723292U true JPH0723292U (en) | 1995-04-25 |
Family
ID=13070484
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5795693U Pending JPH0723292U (en) | 1993-09-29 | 1993-09-29 | Magnetic gradiometer |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0723292U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1138108A (en) * | 1997-07-17 | 1999-02-12 | Uchihashi Estec Co Ltd | Multihead magnetic field sensor |
-
1993
- 1993-09-29 JP JP5795693U patent/JPH0723292U/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1138108A (en) * | 1997-07-17 | 1999-02-12 | Uchihashi Estec Co Ltd | Multihead magnetic field sensor |
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