JPS60202374A - Detection of magnetic body - Google Patents

Detection of magnetic body

Info

Publication number
JPS60202374A
JPS60202374A JP59059811A JP5981184A JPS60202374A JP S60202374 A JPS60202374 A JP S60202374A JP 59059811 A JP59059811 A JP 59059811A JP 5981184 A JP5981184 A JP 5981184A JP S60202374 A JPS60202374 A JP S60202374A
Authority
JP
Japan
Prior art keywords
coil
iron
magnetic
ferrite
frequency
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.)
Pending
Application number
JP59059811A
Other languages
Japanese (ja)
Inventor
Akio Ito
伊藤　昭雄
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NEC Corp
Original Assignee
NEC Corp
Nippon Electric Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by NEC Corp, Nippon Electric Co Ltd filed Critical NEC Corp
Priority to JP59059811A priority Critical patent/JPS60202374A/en
Publication of JPS60202374A publication Critical patent/JPS60202374A/en
Pending legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
    • G01V3/08—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices
    • G01V3/10—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices using induction coils
    • G01V3/104—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices using induction coils using several coupled or uncoupled coils
    • G01V3/105—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices using induction coils using several coupled or uncoupled coils forming directly coupled primary and secondary coils or loops

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Remote Sensing (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Electromagnetism (AREA)
  • Environmental & Geological Engineering (AREA)
  • Geology (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Geophysics (AREA)
  • Geophysics And Detection Of Objects (AREA)

Abstract

PURPOSE:To enable distinguishing a magnetic material as a defective conductor from iron utilizing a requency characteristic varying according to a magnetic body. CONSTITUTION:When alternating current is run to a exciting coil 1 from an oscillator section 3 and a magnetic body 5 approaches the coil 1, an AC magnetic field about the coil is disturbed. The disturbance of the magnetic field is detected with a coil 2 and the type of the magnetic body 5 is discriminated with a detection circuit 4 depending upon the detection level. In this case, the excitation frequency of the oscillator section 3 is fixed at the frequency f1 lower than the resonance frequency f0 prescribed by the coil 1 and circuit parts and ferrite and iron are identified depending on changes in the detection level. For example, when the detection level is at the point Q, ferrite is discrimated and when it at the point R, iron is done.

Description

【発明の詳細な説明】 （産業上の利用分野） 本発明は磁性体検知方法に関し、特に交流磁場を用いた
検知方法に関するものである。DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a magnetic substance detection method, and particularly to a detection method using an alternating current magnetic field.

（従来技術とその問題点） 周知のように鉄等の磁性体を検知する１つの方法として
、交流磁場を用いる仁とが行なわれている。これは交流
磁場をコイルで励起し、磁性体の存在によって乱される
磁束を検知し、磁性体を検知しようとするものである。(Prior Art and its Problems) As is well known, one method of detecting magnetic materials such as iron is to use an alternating current magnetic field. This is an attempt to detect a magnetic material by exciting an alternating magnetic field with a coil and detecting the magnetic flux disturbed by the presence of a magnetic material.

この検知方法においては、励起用コイルは共振状態で動
作させることが一般に行なわれている。これは周知のよ
うＫ。In this detection method, the excitation coil is generally operated in a resonant state. This is well known K.

共振状態でコイルに最も多くの電流を流すことができ、
効率的に交流磁場を発生することができるためである。The most current can be passed through the coil in a resonant state,
This is because an alternating current magnetic field can be efficiently generated.

とζろで近年、鉄と同様な磁性体材料であるフエライト
全磁気的な標識体として用いることか、例えば特願昭５
５年第０８７５９７号（発明の名称「磁気標識体」）に
述べられている。In recent years, ferrite, which is a magnetic material similar to iron, has been used as a totally magnetic marker, for example,
No. 5, No. 087597 (title of invention: "Magnetic label").

それは、フェライトが化学的に安定な磁性材であ夛、鉄
のようにさびるようなことがなく、磁気標識体として用
いるのに適しているからである。こ　□のようにフェラ
イトを磁気、標識体として用いて実用化するにあたって
は、先に述べた従来の検知方法で検知しようとしても次
のような問題点が生じ　□る。即ち、鉄は例えば道路に
おいてはマンホールの蓋や工事用の鉄板として、また建
物等においては鉄筋や鉄骨として、一般に建築物や構造
物材料として広く使われてお）磁気標識体として用いる
フェライトと鉄とを識別する必要がある。第１図は交流
磁場を用いて磁性体検知に一般に用いられる、回路の基
本構成を示す概念図である。This is because ferrite is a chemically stable magnetic material that does not rust like iron, making it suitable for use as a magnetic marker. When ferrite is put to practical use as a magnet or marker as described above, the following problems arise even if the conventional detection methods mentioned above are used to detect it. In other words, iron is widely used as a material for buildings and structures, for example, as manhole covers and iron plates for construction on roads, and as reinforcing bars and steel frames in buildings.) Ferrite and iron are used as magnetic markers. It is necessary to identify the FIG. 1 is a conceptual diagram showing the basic configuration of a circuit generally used for detecting magnetic substances using an alternating magnetic field.

即ち、発振部３で励起用コイル１に交流を流し、そのコ
イル周辺に交流磁場を発生させる。そして磁性体５がと
やコイルに接近すると、この交流磁場が乱される。検出
コイル２で磁場の乱れを検出し検出回路部４で電気的に
増幅や判別等を行なうことが一般に行なわれている。と
ころで従来は、発振部３の周波数を、励起用コイルｌの
共振周波数（１０）に固定して用いられているのが通常
であった。その理由はコイルの共振状態では、電気的抵
抗（インピーダンス）が最小となシ、より多くの電流を
励起コイル１に流すことができ、従ってよシ強い磁場を
発生することが可能なためである。That is, the oscillator 3 applies an alternating current to the excitation coil 1 to generate an alternating magnetic field around the coil. When the magnetic body 5 approaches the coil, this alternating magnetic field is disturbed. Generally, the detection coil 2 detects disturbances in the magnetic field, and the detection circuit section 4 electrically amplifies, discriminates, etc. By the way, in the past, the frequency of the oscillation section 3 was usually fixed at the resonance frequency (10) of the excitation coil l. The reason for this is that when the coil is in a resonant state, the electrical resistance (impedance) is at its minimum, allowing more current to flow through the excitation coil 1 and therefore generating a stronger magnetic field. .

しかし、従来のようにコイルの共振状態（共−振周波数
ｆ。）を利用し、ｆｏの励振周波数で交流磁場を発生さ
せたのでは、鉄とフェライトとを識別することが困難で
あった。However, if the resonant state of the coil (resonant frequency f) is used to generate an alternating current magnetic field at the excitation frequency fo as in the conventional method, it is difficult to distinguish between iron and ferrite.

（発明の目的） 本発明はフェライト等の不良導体磁性材と、鉄と同様な
良導体磁性材とを識別可能な磁性体検知方法を提供する
ことにある。(Object of the Invention) An object of the present invention is to provide a magnetic material detection method that can distinguish between a bad conductor magnetic material such as ferrite and a good conductor magnetic material similar to iron.

（発明の構成） 本発明は励起用コイルを用いて交流磁場を励振し、不良
導体の磁性体を検出する方法において、前記励起用コイ
ルを励振させる周波数を、該コイルと回路部品で規定さ
れる共振周波数よシ低く設定し、その電圧レベルの変化
によシ磁性体の種類を識別することを特徴とする磁性体
検知方法である。(Structure of the Invention) The present invention provides a method for detecting a magnetic substance in a defective conductor by exciting an alternating current magnetic field using an excitation coil, in which the frequency at which the excitation coil is excited is defined by the coil and circuit components. This magnetic material detection method is characterized by setting the resonance frequency lower than the resonance frequency and identifying the type of magnetic material based on changes in the voltage level.

（実施例） 以下、本発明の実施例について第２図を参照して詳細に
説明する。(Example) Hereinafter, an example of the present invention will be described in detail with reference to FIG. 2.

曲線Ａは磁性体５（第１図参照）が検知距離範囲内にな
いときの、励起コイルの周波数特性を示す。同図から明
らかなように共振周波数ｆ。（磁性体がないときのセン
サ共振点）である。Curve A shows the frequency characteristic of the excitation coil when the magnetic body 5 (see FIG. 1) is not within the detection distance range. As is clear from the figure, the resonance frequency f. (sensor resonance point when there is no magnetic material).

曲線Ｂは、磁性体５がフェライトであシ、検知距離範囲
内に入ったときの同様な特性である。明らかなようにそ
のときの共振周波数ｆ０′（フェライト接近時のセンサ
共振点）はｆｏよシ低下する。フェライトがよシ接近す
ると、共振周波数は更に下る（図示せず）。またそれぞ
れの共振周波数でのレベルは曲線Ａ、Ｂから分るように
あまシ変化しないことが分る。一方、フェライトと同様
な軟磁性材である鉄が検知距離範囲内に入ったときの、
周波数特性を曲線Ｃで示す。フェライトのときと異なシ
、そのときの共振周波数ｆ：（鉄接近時のセンサ共振点
）はｆｏよシ上昇する。しかも曲線Ｃ全体の電圧レベル
は低下している。これは鉄によシ渦電流損失が起きるた
めと解釈される。Curve B shows similar characteristics when the magnetic material 5 is made of ferrite and is within the detection distance range. As is clear, the resonance frequency f0' (sensor resonance point when approaching the ferrite) at that time is lower than fo. As the ferrite gets closer, the resonant frequency drops further (not shown). Furthermore, as can be seen from curves A and B, the levels at each resonant frequency do not change much. On the other hand, when iron, a soft magnetic material similar to ferrite, comes within the detection distance,
Curve C shows the frequency characteristics. Unlike when using ferrite, the resonance frequency f: (sensor resonance point when approaching iron) is higher than f. Moreover, the voltage level of the entire curve C is decreasing. This is interpreted to be due to eddy current loss occurring due to iron.

本発明はこのような磁性体に応じて変化する周波数特性
を利用し、フェライトと鉄との識別を行なうものである
。即ち、本来の励起用コイルと回路部品とで規定される
共振周波数ｆ０よシ低い周波数、例えばｆｌ　（磁性体
がないときの励振用周波数固定点）に励損用周波数を固
定し、その電圧レベルの変化から識別するものである。The present invention utilizes such frequency characteristics that change depending on the magnetic material to distinguish between ferrite and iron. That is, the excitation frequency is fixed at a frequency lower than the resonance frequency f0 defined by the original excitation coil and circuit components, for example, fl (the excitation frequency fixed point when there is no magnetic material), and the voltage level is It can be identified from the change in

磁性体が接近しないときには電圧はＰ点（磁性体がない
ときの励振用周波数固定点）に相当するものである。When the magnetic body does not approach, the voltage corresponds to point P (excitation frequency fixed point when there is no magnetic body).

フェライトが接近したときには電圧は９点（フェライト
接近時の電圧移動点）に相当し、上昇し、鉄が接近した
ときにはＲ点（鉄接近時の電圧移動点）に相当し、低下
する。When the ferrite approaches, the voltage corresponds to point 9 (voltage shifting point when ferrite approaches) and rises, and when iron approaches, it corresponds to point R (voltage shifting point when iron approaches) and decreases.

このように励起周波数をｆｏよシ低く設定するととによ
シフエライトと鉄を識別できることが分る。It can be seen that if the excitation frequency is set lower than fo in this way, it is possible to distinguish between toyoshiferite and iron.

一方、励起周波数をｆｏよシ高く、例えばｆｚ　（磁性
体がないときの励振用周波数固定点）に設定すると、そ
の識別は困難となる。即ち、磁性体が接近していなかっ
たときの電圧はＰ′点（磁性体がないときの励振用周波
数固定点）に相当するが、フェライトや鉄のいずれもが
接近しても電圧はそれぞれ９１点（フェライト接近時の
電圧移動点）、Ｒ′点（鉄接近時の電圧移動点）に示さ
れるように低下してしまう。またその電圧低下の様子は
磁性体の接近種度によシ異なるので、電圧低下の程度か
らも鉄とフェライトの峻別は困難である。On the other hand, if the excitation frequency is set higher than fo, for example fz (excitation frequency fixed point when there is no magnetic material), identification becomes difficult. In other words, the voltage when no magnetic material is close corresponds to point P' (the excitation frequency fixed point when there is no magnetic material), but even when ferrite and iron are close, the voltage is 91. The voltage decreases as shown at point R' (voltage shift point when approaching ferrite) and R' point (voltage shift point when approaching iron). Furthermore, since the manner of voltage drop differs depending on the degree of proximity of the magnetic material, it is difficult to distinguish between iron and ferrite based on the degree of voltage drop.

また従来技術で行なわれていたように、励起周波数をｆ
に固定していたのでは同図から明らかなようにｆ：の例
で述べたと同様に識別は困難である。Also, as was done in the prior art, the excitation frequency is
As is clear from the figure, if it is fixed at f:, it is difficult to identify it as described in the example of f:.

以上本発明の実施例をフェライトと鉄での特性を用いて
述べてきたが、本発明がこれに限定されるものでなく、
フェライトの替わシにフェライトと同様に渦電流損失の
少ない不良導体の磁性体を磁気標識体として用いても、
鉄との識別は可能である。Although the embodiments of the present invention have been described above using the characteristics of ferrite and iron, the present invention is not limited to this.
Even if a magnetic material with poor conductivity and low eddy current loss is used as a magnetic marker instead of ferrite,
It is possible to distinguish it from iron.

また、本発明は励起周波数をｆｏよシ下げて用いること
を述べた。その下限は原理的にはないが、必要以上に下
げると、実効的な検知感度を低下させることになり好ま
しくない。本発明では下限値することが望ましい。Furthermore, it has been described that the present invention is used with the excitation frequency lower than fo. Although there is no lower limit in principle, lowering it more than necessary is undesirable because it reduces the effective detection sensitivity. In the present invention, a lower limit value is desirable.

（発明の効果） 以上詳細に述べた通シ本発明によれば、従来方式の不良
導体磁性材と鉄の識別が不可能であったのに比べて、不
良導体磁性材と鉄の識別ができ、実用的であるという効
果を有するものである。(Effects of the Invention) According to the present invention described in detail above, it is possible to distinguish between a defective conductor magnetic material and iron, compared to the conventional method in which it was impossible to distinguish between a defective conductor magnetic material and iron. , it has the effect of being practical.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は回路の基本構成を示す概念図、第２図は本発明
の一実施例を示す特性図である。 １・・・励起用コイル、５・・・磁性体。FIG. 1 is a conceptual diagram showing the basic configuration of the circuit, and FIG. 2 is a characteristic diagram showing one embodiment of the present invention. 1... Excitation coil, 5... Magnetic material.

Claims (1)

【特許請求の範囲】[Claims] （１）　励起用コイルを用いて交流磁場を励振し、不良
導体の磁性体を検出する方法において、前記励起用コイ
ルを励振させる周波数を、該励起用コイルと回路部品で
規定される共振周波数よシ低く設定し、その電圧レベル
の変化によシ磁性体の種類を識別することを特徴とする
磁性体検知方法。(1) In a method of detecting a magnetic material in a bad conductor by exciting an alternating current magnetic field using an excitation coil, the frequency at which the excitation coil is excited is set to a resonance frequency defined by the excitation coil and circuit components. A method for detecting a magnetic substance, characterized in that the voltage level is set low and the type of magnetic substance is identified based on changes in the voltage level.
JP59059811A 1984-03-28 1984-03-28 Detection of magnetic body Pending JPS60202374A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP59059811A JPS60202374A (en) 1984-03-28 1984-03-28 Detection of magnetic body

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP59059811A JPS60202374A (en) 1984-03-28 1984-03-28 Detection of magnetic body

Publications (1)

Publication Number Publication Date
JPS60202374A true JPS60202374A (en) 1985-10-12

Family

ID=13123989

Family Applications (1)

Application Number Title Priority Date Filing Date
JP59059811A Pending JPS60202374A (en) 1984-03-28 1984-03-28 Detection of magnetic body

Country Status (1)

Country Link
JP (1) JPS60202374A (en)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5359550A (en) * 1976-11-04 1978-05-29 Daito Seisakusho Pachinko game ball detecting method
JPS5940287A (en) * 1982-08-31 1984-03-05 Anritsu Corp Apparatus for detecting metal

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5359550A (en) * 1976-11-04 1978-05-29 Daito Seisakusho Pachinko game ball detecting method
JPS5940287A (en) * 1982-08-31 1984-03-05 Anritsu Corp Apparatus for detecting metal

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