JPS642904B2 - - Google Patents
Info
- Publication number
- JPS642904B2 JPS642904B2 JP57169645A JP16964582A JPS642904B2 JP S642904 B2 JPS642904 B2 JP S642904B2 JP 57169645 A JP57169645 A JP 57169645A JP 16964582 A JP16964582 A JP 16964582A JP S642904 B2 JPS642904 B2 JP S642904B2
- Authority
- JP
- Japan
- Prior art keywords
- signal
- synchronous
- frequency
- metal
- phase
- 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.)
- Expired
Links
- 229910052751 metal Inorganic materials 0.000 claims description 42
- 239000002184 metal Substances 0.000 claims description 42
- 238000001514 detection method Methods 0.000 claims description 39
- 230000001360 synchronised effect Effects 0.000 claims description 36
- 230000003287 optical effect Effects 0.000 claims description 2
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 20
- 230000035945 sensitivity Effects 0.000 description 20
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 15
- -1 ferrous metals Chemical class 0.000 description 13
- 238000010586 diagram Methods 0.000 description 8
- 229910052742 iron Inorganic materials 0.000 description 6
- 150000002739 metals Chemical class 0.000 description 3
- 239000008186 active pharmaceutical agent Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000010363 phase shift Effects 0.000 description 2
- 235000013580 sausages Nutrition 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
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
- G01V3/107—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 using compensating coil or loop arrangements
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)
- Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
- Geophysics And Detection Of Objects (AREA)
Description
【発明の詳細な説明】
この発明は、コンベア等で搬送されている被検
査体（特に食品）中にどのような種類の金属が混
入しているか否かを高い感度指数で検出すること
ができる金属検出装置に関するものである。[Detailed Description of the Invention] This invention is capable of detecting with a high sensitivity index what kind of metal is mixed in an object to be inspected (especially food) being transported by a conveyor or the like. This invention relates to a metal detection device.
まず、従来から使用されている金属検出装置の
概要について第１図で説明する。 First, an overview of a conventionally used metal detection device will be explained with reference to FIG.
この図において、１は発振器、２は前記発振器
１に接続されている送信コイル、３ａ，３ｂはこ
の送信コイル２に対向して配置されている受信コ
イルで、この受信コイル３ａ，３ｂは、送信コイ
ル２の交番磁界中におかれ、その磁力線が等しく
交錯するように配置されている。 In this figure, 1 is an oscillator, 2 is a transmitting coil connected to the oscillator 1, 3a and 3b are receiving coils arranged opposite to this transmitting coil 2, and these receiving coils 3a and 3b are It is placed in the alternating magnetic field of the coil 2 and arranged so that the lines of magnetic force intersect equally.
４ａ，４ｂは、前記受信コイル３ａ，３ｂの誘
起電圧e〓1，e〓2の位相及び振幅の調整用のボリユー
ムを示し、このボリユーム４ａ，４ｂの調整によ
つて、通常は受信コイル３ａ，３ｂの差動誘起電
圧がe〓1−e〓2＝０となるように設定される。５は差
動誘起電圧e〓1−e〓2を増幅する増幅器、６ａ，６ｂ
はそれぞれ鉄及び非鉄金属を検出する同期検波
器、７ａ，７ｂはフイルタ、８ａ，８ｂは判別回
路である。なお、９ａ，９ｂは前記同期検波器６
ａ，６ｂに供給する同期信号を形成する第１、第
２の移相器を示す。 4a, 4b indicate volumes for adjusting the phase and amplitude of the induced voltages e〓 1 , e〓 2 of the receiving coils 3a, 3b. By adjusting the volumes 4a, 4b, the receiving coils 3a, 3b are normally adjusted. The differential induced voltage of 3b is set so that e〓 1 −e〓 2 =0. 5 is an amplifier that amplifies the differential induced voltage e〓 1 −e〓 2 , 6a, 6b
are synchronous detectors for detecting ferrous and non-ferrous metals, 7a and 7b are filters, and 8a and 8b are discrimination circuits. Note that 9a and 9b are the synchronous detectors 6
Fig. 6 shows first and second phase shifters that form synchronization signals supplied to terminals a and 6b.
かヽる構成からなる金属検出装置は、送信コイ
ル２、及び受信コイル３ａ，３ｂ間に被検査体Ｗ
が通過し、該被検査体Ｗに金属が混入している時
は、その金属の種類（鉄、又は非鉄金属）によつ
て判別回路８ａ，８ｂに検出信号が発生する。 A metal detection device having a tilted configuration has an object W to be inspected between a transmitting coil 2 and receiving coils 3a and 3b.
passes through and when metal is mixed in the object W to be inspected, a detection signal is generated in the discrimination circuits 8a and 8b depending on the type of metal (ferrous or non-ferrous metal).
この点を第２図ａ，ｂのベクトル図で説明する
と、通常、受信コイル３ａ，３ｂの誘起電圧e〓1，
e〓2は増幅器５の入力側においてe〓1−e〓2＝０となる
ように設定されているが、鉄を含んだ被検査体Ｗ
が矢印の方向から通過すると、まず第２図ａに示
すように受信コイル３ａの誘起電圧e〓1がe〓′1に増
大し、次に受信コイル３ｂの誘起電圧e〓2がe〓′2に
増大する。したがつて、e〓1−e〓2＝e〓Dfの差動誘起
電
圧が同期検波器６ａに入力され、この同期検波器
６ａに供給されている同位相の同期検波用の信号
e〓Fによつて検出される。 To explain this point using the vector diagrams in Fig. 2 a and b, normally, the induced voltages e〓 1 ,
e〓 2 is set so that e〓 1 −e〓 2 = 0 on the input side of the amplifier 5, but the test object W containing iron
passes from the direction of the arrow, first the induced voltage e〓 1 of the receiving coil 3a increases to e〓' 1 as shown in Fig. 2a, and then the induced voltage e〓 2 of the receiving coil 3b increases to e〓' Increases to 2 . Therefore, the differential induced voltage of e〓 1 −e〓 2 = e〓 Df is input to the synchronous detector 6a, and the same phase synchronous detection signal is supplied to the synchronous detector 6a.
e〓 Detected by F.
一方、非鉄金属（ステンレス・アルミ等）が混
入した被検査体Ｗが通過すると発振器１の光流磁
界の影響をうけて非鉄金属内に渦電流が流れる。
するとこの渦電流の影響によつて、受信コイル３
ａ，３ｂの誘起電圧e〓1，e〓2の位相が変化すること
になる。 On the other hand, when the inspected object W containing non-ferrous metals (stainless steel, aluminum, etc.) passes through, eddy currents flow in the non-ferrous metals under the influence of the optical magnetic field of the oscillator 1.
Then, due to the influence of this eddy current, the receiving coil 3
The phases of the induced voltages e〓 1 and e〓 2 of a and 3b will change.
すなわち、第２図ｂに示すように受信コイル３
ａの誘起電圧e〓1の位相がe〓″1に変化すると、差動
誘起電圧e〓″1−e〓2＝e〓DSは、図示したようにほぼ9
0゜
位相がずれた点に発生する。そこで、この差動誘
起電圧e〓DSとほぼ同位相のe〓sで示した同期検波信
号が供給されている同期検波器６ｂにおいて位相
検波することにより、非鉄を検出することができ
る。 That is, as shown in FIG. 2b, the receiving coil 3
When the phase of the induced voltage e〓 1 of a changes to e〓″ 1 , the differential induced voltage e〓″ 1 −e〓 2 = e〓 DS becomes approximately 9 as shown in the figure.
Occurs at a point with a 0° phase shift. Therefore, non-ferrous metals can be detected by performing phase detection in the synchronous detector 6b, which is supplied with a synchronous detection signal indicated by e〓s having approximately the same phase as this differential induced voltage e〓 DS .
以上は被検査体Ｗの金属検出動作について簡単
に説明したが、次に発振器１から供給される周波
数と金属の検出感度について考察する。 The metal detection operation of the object W to be inspected has been briefly explained above, but next, the frequency supplied from the oscillator 1 and the metal detection sensitivity will be considered.
第３図は発振器１の周波数を変化した場合の鉄
（Fe）と非鉄金属（ステンレス：SUS）、及び製
品（ソーセージ）における、感度指数を示したも
のである。この図から、鉄（Fe）は周波数（横
軸）を変化した場合も一定の感度指数を示し、検
出感度は変化しないが、非鉄金属（SUS）、及び
製品は渦電流損が周波数の２乗に比例することか
ら周波数が高くなると鉄より感度指数が高くな
り、したがつて、鉄（Fe）のみを検出するため
には周波数がl附近の低い信号の方が良いことが
分かる。 FIG. 3 shows the sensitivity index for iron (Fe), nonferrous metal (stainless steel: SUS), and product (sausage) when the frequency of the oscillator 1 is changed. This figure shows that iron (Fe) shows a constant sensitivity index even when the frequency (horizontal axis) changes, and the detection sensitivity does not change, but for non-ferrous metals (SUS) and products, the eddy current loss is the square of the frequency. Since it is proportional to , the higher the frequency, the higher the sensitivity index is than that of iron. Therefore, in order to detect only iron (Fe), it is clear that a low signal with a frequency around l is better.
一方、非鉄金属（SUS）とハム又はソーセジ
等の製品の検出感度を比較すると、第４図に示す
ように検出信号の検波する位相により感度指数が
変化し、SUSでは0゜附近で最大となり、90゜附近
で最低となつているが、製品の場合は波線で示す
ようにその物性により非鉄金属（SUS）と異な
る位相で最低点が存在する。 On the other hand, when comparing the detection sensitivity of nonferrous metals (SUS) and products such as ham or sausage, the sensitivity index changes depending on the detected phase of the detection signal, as shown in Figure 4, and for SUS it reaches a maximum around 0°. The lowest point is around 90 degrees, but in the case of products, the lowest point exists at a different phase from non-ferrous metals (SUS) due to their physical properties, as shown by the wavy line.
そして、非鉄金属（SUS）と、製品の最低感
度となる点の位相差は、低い周波数lに比較して
高い周波数hになる程大きくなることが分かる。 It can also be seen that the phase difference between the non-ferrous metal (SUS) and the point at which the product has the lowest sensitivity becomes larger as the frequency h becomes higher compared to the lower frequency l .
すなわち、第４図で非鉄金属（SUS）と製品
の感度差は、低い周波数lでは同期検波信号の位
相差を80゜位に選んだ時、ａ−ｂ間の大きさにな
るが、高い周波数hの時はa′−b′間の感度差（位
相はほぼ70゜位に選ぶ）が得られるので、周波数
は高い方が製品と非鉄を判別する時に有利である
ことがわかる。 In other words, in Figure 4, the sensitivity difference between non-ferrous metal (SUS) and the product is between a and b when the phase difference of the synchronous detection signal is selected to be about 80 degrees at low frequencies l , but at high frequencies At h , the sensitivity difference between a' and b' (the phase is chosen to be about 70 degrees) is obtained, so it can be seen that a higher frequency is more advantageous when distinguishing between products and non-ferrous metals.
この発明は、上述したようなデータの解析から
鉄、非鉄金属の感度指数のいずれも高くなるよう
に２周波を使用して金属検出装置を構成したもの
である。 According to the present invention, a metal detection device is constructed using two frequencies so that the sensitivity index for both ferrous and non-ferrous metals is high based on the analysis of the data as described above.
以下、この発明の金属検出装置の一実施例を第
５図の回路ブロツクにより説明する。 Hereinafter, one embodiment of the metal detection device of the present invention will be explained with reference to the circuit block shown in FIG.
この図において、１０は周波数がhの発振器、
１１は分周比１／2nの分周器、１２は前記分周器１
１によつて逓降した周波数lの信号と、前記発振
器１０の周波数hの信号を加算する加算器、１
３，１４は金属検出装置の送信、及び受信コイ
ル、１５は差動増幅器、１６ａ，１６ｂは前述し
たように鉄、及び非鉄金属の同期検波器を示し、
鉄の方の同期検波用の信号は移相器１９ａを介し
て逓降した周波数lの信号が、非鉄金属の同期検
波用の信号には移相器１９ｂを介して周波数hの
信号が供給されている。 In this figure, 10 is an oscillator with a frequency of h ,
11 is a frequency divider with a frequency division ratio of 1/2n; 12 is an adder for adding the signal of frequency l that has been stepped down by the frequency divider 11 and the signal of frequency h from the oscillator 10;
3 and 14 are transmitting and receiving coils of the metal detection device, 15 is a differential amplifier, 16a and 16b are synchronous detectors for ferrous and non-ferrous metals as described above,
The signal for synchronous detection of ferrous metals is supplied with a signal of frequency l that is stepped down through a phase shifter 19a, and the signal of frequency h is supplied through a phase shifter 19b for the signal of synchronous detection of non-ferrous metals. ing.
なお、１７ａ，１７ｂはフイルタ、１８ａ，１
８ｂは金属の有無を判断する信号を出力する判別
回路を示す。 Note that 17a, 17b are filters, 18a, 1
Reference numeral 8b indicates a determination circuit that outputs a signal for determining the presence or absence of metal.
つづいて、上記実施例の動作を第６図の波形図
に基づいて説明する。 Next, the operation of the above embodiment will be explained based on the waveform diagram of FIG.
発振器１０から出力される信号の周波数hは第
４図のデータで説明したように非鉄金属（SUS）
と製品の感度指数の差が大きくなる周波数hを採
用する。この周波数hの信号は分周器１１におい
て１／2nに分周されるが、逓降された周波数lは
第３図のデータで説明した鉄と非鉄（製品）の感
度指数の差が大きくなる周波数lとなるように分
周する。そしてこれら２つの周波数h、lは加算
器１２において単純に加算され送信コイル１３に
供給される。 The frequency h of the signal output from the oscillator 10 is determined by the non-ferrous metal (SUS) as explained in the data in Fig. 4.
The frequency h at which the difference between the sensitivity index of the product and the sensitivity index of the product becomes large is adopted. This signal with frequency h is divided into 1/2n by the frequency divider 11, but the down-done frequency l has a large difference in the sensitivity index between ferrous and non-ferrous (products) as explained in the data in Figure 3. Divide the frequency to l . Then, these two frequencies h and l are simply added in an adder 12 and supplied to a transmitting coil 13.
第６図の波形(A)は、h＝4l（ｎ＝２）の関係と
なつている混合波h＋lを示している。 Waveform (A) in FIG. 6 shows a mixed wave h + l having the relationship h = 4 l (n = 2).
このような混合波h＋lが送信コイル１３に供
給されても、被検査体Ｗが送信コイル１３と受信
コイル１４の間に存在しない時は、差動増幅器１
５の合成出力は零であり、同期検波器１６ａ，１
６ｂにも何んらの信号も発生しない。 Even if such a mixed wave h + l is supplied to the transmitting coil 13, when the object W to be inspected is not present between the transmitting coil 13 and the receiving coil 14, the differential amplifier 1
The combined output of 5 is zero, and the synchronous detectors 16a, 1
6b also does not generate any signal.
今、この状態で鉄が混入された被検査体Ｗが通
過すると、受信コイル１４の誘起電圧e〓1，e〓2のバ
ランス、特にに振幅の平衡性が失なわれるので、
混合波h＋lとほぼ同様な波形(A)が差動出力とし
て同期検波器１６ａ，１６ｂに供給される。 Now, if the inspected object W mixed with iron passes through in this state, the balance of the induced voltages e〓 1 and e〓 2 of the receiving coil 14, especially the balance of the amplitude, will be lost.
A waveform (A) substantially similar to the mixed wave h + l is supplied to the synchronous detectors 16a and 16b as a differential output.
ところが同期検波器１６ａに供給されている同
期検波用の信号e〓Fは、第６図の波形(B)に示すよう
に周波数lの信号の位相とほぼ同一の位相となる
ように移相器１９ａによつて設定してあるので、
その同期検波出力は波形(C)のように検出される。
したがつて、これをフイルタ１７ａで平滑すると
ほぼ平均値がEfの号が得られ、この信号で判別回
路１８ａが動作して、鉄の混入を報知する。 However, the signal e〓 F for synchronous detection supplied to the synchronous detector 16a is processed by a phase shifter so that it has almost the same phase as the signal of frequency l , as shown in the waveform (B) of FIG. Since it is set by 19a,
The synchronous detection output is detected as shown in waveform (C).
Therefore, when this is smoothed by the filter 17a, an approximately average value of E f is obtained, and this signal operates the discrimination circuit 18a to notify the presence of iron contamination.
一方、非鉄の同期検波器１６ｂに供給されてい
る同期検波用の信号e〓Sの波形(D)は、その周波数が
hで、かつ被検査体Ｗを構成する製品の感度指数
が最低となる位相βに設定されているので、この
同期検波用の信号e〓Sで検波された信号は波形(E)に
示すように正側及び負側において、ほぼ同一の検
波信号となりフイルタ１７ｂを通過すると零レベ
ルの検波出力Esとなるので、非鉄の判別回路１
８ｂは動作しない。 On the other hand, the waveform (D) of the signal e〓 S for synchronous detection supplied to the non-ferrous synchronous detector 16b has a frequency of
h , and the sensitivity index of the product constituting the inspected object W is set to the lowest phase β, so the signal detected by this synchronous detection signal e〓 S is as shown in the waveform (E). The detection signal becomes almost the same on the positive side and the negative side, and when it passes through the filter 17b, the detection output Es becomes zero level, so the non-ferrous discrimination circuit 1
8b does not work.
次に、前記被検査体Ｗに非鉄金属（SUS）が
混入している場合について説明する。 Next, a case where non-ferrous metal (SUS) is mixed in the object W to be inspected will be described.
低い周波数lに対しては第３図のデータ図で説
明したように渦電流の影響が小さいので、周波数
l成分は受信コイル１４内でキヤンセルされてほ
とんど出力されない。したがつて、製品内に非鉄
金属（SUS）が混入しているときは、この非鉄
金属（SUS）によつて移相された高い周波数hが
差動誘起電圧e〓1−e〓2として波形（A′）に示すよう
に鉄の同期検波器１６ａ及び非鉄の同期検波器１
６ｂに入力され同期検波されるが、鉄の同期検波
器１６ａの同期検波出力は波形（C′）に示すよう
に正負対象の波形となつているので、フイルタ１
７ａで除去され、判別回路１８ａからは検出信号
が出力されていない。 As explained in the data chart in Figure 3, the influence of eddy currents is small for low frequencies , so the frequency
The l component is canceled within the receiving coil 14 and is hardly output. Therefore, when a non-ferrous metal (SUS) is mixed in the product, the high frequency h phase-shifted by the non-ferrous metal (SUS) is waveformed as a differential induced voltage e〓 1 −e〓 2 . As shown in (A'), a ferrous synchronous detector 16a and a non-ferrous synchronous detector 1
However, since the synchronous detection output of the iron synchronous detector 16a has a positive and negative waveform as shown in the waveform (C'), the filter 1
7a, and no detection signal is output from the discrimination circuit 18a.
しかし、前記差動誘起電圧の波形（A′）が非
鉄の同期検波器１６ｂに入力され、同期検波用の
信号e〓Sで検波されるとその同期検波出力は位相ず
れを受けているため波形（E′）に示すように一方
向のみ出力される。この信号（E′）はフイルタ１
７ｂに入力されるとE′sに示す検出電圧となり、
判別回路１８ｂを動作させることになる。 However, when the waveform (A') of the differential induced voltage is input to the nonferrous synchronous detector 16b and detected by the synchronous detection signal e〓 S , the synchronous detection output has a phase shift, so the waveform As shown in (E'), the signal is output in only one direction. This signal (E') is filtered by filter 1.
When input to 7b, the detected voltage becomes E′s,
This causes the discrimination circuit 18b to operate.
以上、２つの周波数l、hについて説明した
が、製品の感度指数は、その材質によつて変化
し、その最低感度となる位相も変化する。したが
つて、２周波に限らず３周波（但し偶数倍とした
もの）以上の信号を混合したものを送信コイル１
３に供給するようにして各周波数成分を複数の同
期検波器で検波するようにしてもよい。 The two frequencies l and h have been explained above, but the sensitivity index of a product changes depending on its material, and the phase at which it has the lowest sensitivity also changes. Therefore, the transmitting coil 1 is a mixture of signals of not only 2 frequencies but also 3 frequencies (however, an even number) or more.
3, and each frequency component may be detected by a plurality of synchronous detectors.
以上説明したように、この発明の金属検出装置
は送信コイルを２周波h＋lで駆動し、鉄の検出
は製品に影響が少ない低い方の周波数lで検出
し、非鉄金属の検出は感度が高く、かつ位相識別
の良好な高い周波数hで検出するようにしたの
で、鉄、非鉄金属とも高感度で検出することがで
きる。 As explained above, the metal detection device of the present invention drives the transmitter coil at two frequencies h + l , detects iron at the lower frequency l that has less effect on the product, and detects non-ferrous metals at the lower frequency l, which has less effect on the product. Since detection is performed at a high frequency h with good phase discrimination, both ferrous and non-ferrous metals can be detected with high sensitivity.
しかも、かゝる２周波を使用する場合も、送信
コイルと受信コイルが従来と同様に１組あればよ
く、構造が簡単であるとともに、高い周波数hの
信号と低い周波数lの信号を偶数倍（2n倍）とな
るように設定しているので、各々の周波数l、及
びhを分離するための特別な分離選択回路がなく
とも同期検波することができるので、回路構成が
簡単になるという利点を有するものである。 Moreover, even when using such two frequencies, just one pair of transmitting coil and receiving coil is required as in the past, and the structure is simple, and the signal of high frequency h and signal of low frequency l can be divided by an even number. (2n times), synchronous detection can be performed without a special separation selection circuit to separate each frequency l and h , which has the advantage of simplifying the circuit configuration. It has the following.
第１図は従来の金属検出装置のブロツク図、第
２図ａ，ｂは鉄、非鉄金属を検出するときのベク
トル図、第３図、第４図は鉄、非鉄金属（SUS、
Al等）、及び製品に対する感度指数と、供給周波
数及び位相関係を説明するためのデータ図、第５
図はこの発明の一実施例を示す金属検出装置のブ
ロツク図、第６図は第５図のブロツク図における
検出動作の波形図である。
図中、１０は発振器、１１は分周器、１２は加
算器、１３は送信コイル、１４は受信コイル、１
５は差動増幅器、１６ａ，１６ｂは同期検波器、
１７ａ，１７ｂはフイルタ、１８ａ，１８ｂは判
別回路、１９ａ，１９ｂは移相器を示す。
Figure 1 is a block diagram of a conventional metal detection device, Figures 2a and b are vector diagrams for detecting ferrous and nonferrous metals, and Figures 3 and 4 are ferrous and nonferrous metals (SUS,
Al, etc.), and a data diagram for explaining the sensitivity index, supply frequency and phase relationship for the product, Part 5
The figure is a block diagram of a metal detection device showing one embodiment of the present invention, and FIG. 6 is a waveform diagram of the detection operation in the block diagram of FIG. 5. In the figure, 10 is an oscillator, 11 is a frequency divider, 12 is an adder, 13 is a transmitting coil, 14 is a receiving coil, 1
5 is a differential amplifier, 16a and 16b are synchronous detectors,
17a and 17b are filters, 18a and 18b are discrimination circuits, and 19a and 19b are phase shifters.
Claims (1)
（h、l）の信号を重畳した駆動信号によつて駆
動される１個の送信コイルと、前記送信コイルの
磁界と光鎖し、通過する被検査体によつて誘起電
圧が変化する２つの受信コイルと、前記２つの受
信コイルの誘起電圧の差信号を形成する差動増幅
器と、前記差動増幅器の出力を同期検波する少な
くとも２つの同期検波器と、該同期検波器の出力
から前記被検査体に混入された金属の有無を判別
する判別回路とを備え、前記２つの同期検波器の
一方には、前記駆動信号の中の低い周波数（l）
の信号成分を同期検波信号としてほぼ同一位相で
供給し、前記誘起電圧の差信号の振幅変化を検出
すると共に、前記２つの同期検波器の他方には、
前記駆動信号の中の高い周波数（h）の信号成分
をほぼ90゜移相した同期検波信号を供給し、前記
誘起電圧の差信号の位相変化を検出するように構
成したことを特徴とする金属検出装置。 ２ 少なくとも２つの周波数（h、l）の信号
は、１つの発振器からの信号と、これを分周した
信号で形成されていることを特徴とする特許請求
の範囲第１項記載の金属検出装置。[Claims] 1. One transmitting coil driven by a drive signal obtained by superimposing signals of at least two frequencies ( h , l ) that are even multiples, and the magnetic field and optical chain of the transmitting coil. and two receiving coils whose induced voltage changes depending on the passing object to be inspected, a differential amplifier that forms a difference signal between the induced voltages of the two receiving coils, and synchronous detection of the output of the differential amplifier. It is equipped with at least two synchronous detectors and a discrimination circuit that determines the presence or absence of metal mixed in the object to be inspected based on the output of the synchronous detectors, and one of the two synchronous detectors is provided with a discriminator that detects the drive signal. medium low frequency ( l )
is supplied as a synchronous detection signal with substantially the same phase, and the amplitude change of the induced voltage difference signal is detected, and the other of the two synchronous detectors is provided with:
The metal is configured to supply a synchronous detection signal in which a high frequency ( h ) signal component of the drive signal is phase-shifted by approximately 90°, and to detect a phase change of the induced voltage difference signal. Detection device. 2. The metal detection device according to claim 1, wherein the signals of at least two frequencies ( h , l ) are formed by a signal from one oscillator and a signal obtained by frequency-dividing the signal. .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57169645A JPS5960277A (en) | 1982-09-30 | 1982-09-30 | Metal detector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57169645A JPS5960277A (en) | 1982-09-30 | 1982-09-30 | Metal detector |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5960277A JPS5960277A (en) | 1984-04-06 |
| JPS642904B2 true JPS642904B2 (en) | 1989-01-19 |
Family
ID=15890315
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP57169645A Granted JPS5960277A (en) | 1982-09-30 | 1982-09-30 | Metal detector |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5960277A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2006009048A1 (en) * | 2004-07-16 | 2006-01-26 | Okayama University | Magnetism sensing apparatus and material determining apparatus |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS629286A (en) * | 1985-07-05 | 1987-01-17 | Tokyo Gas Co Ltd | Method and device for detecting underground installation |
| JP2556740B2 (en) * | 1988-12-29 | 1996-11-20 | 大日本印刷株式会社 | Mixed packaging |
| JPH03125987A (en) * | 1989-10-11 | 1991-05-29 | Anritsu Corp | Metal detector |
| EP2439559B1 (en) | 2010-10-07 | 2013-05-29 | Mettler-Toledo Safeline Limited | Method for operating of a metal detection system and metal detection system |
| EP2439560B1 (en) | 2010-10-07 | 2013-05-29 | Mettler-Toledo Safeline Limited | Method for monitoring the operation of a metal detection system and metal detection system |
| BR112013008207B1 (en) | 2010-10-07 | 2021-06-01 | Mettler-Toledo Safeline Limited | METHOD FOR OPERATING A METAL DETECTION SYSTEM AND A METAL DETECTION SYSTEM |
| US9018935B2 (en) | 2011-09-19 | 2015-04-28 | Mettler-Toledo Safeline Limited | Method for operating a metal detection apparatus and apparatus |
| EP2924472B1 (en) * | 2014-03-25 | 2020-01-15 | Mettler-Toledo Safeline Limited | Method for monitoring the operation of a metal detection system and metal detection system |
| KR102580035B1 (en) * | 2017-01-18 | 2023-09-20 | 한국전자통신연구원 | Method of detecting paramagnetic material using single excitation coil based on mixed signal and apparatus using the same |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5854712Y2 (en) * | 1980-02-29 | 1983-12-13 | 株式会社島津製作所 | metal detector |
| JPS5849996B2 (en) * | 1980-03-13 | 1983-11-08 | 株式会社東芝 | Disconnection detection device for series lighting circuits |
| JPS5845548A (en) * | 1981-09-11 | 1983-03-16 | Nikka Densoku Kk | Detection of conductive object and device for embodying said detection |
-
1982
- 1982-09-30 JP JP57169645A patent/JPS5960277A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2006009048A1 (en) * | 2004-07-16 | 2006-01-26 | Okayama University | Magnetism sensing apparatus and material determining apparatus |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5960277A (en) | 1984-04-06 |
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