JP2004077349A

JP2004077349A - Metal detecting device

Info

Publication number: JP2004077349A
Application number: JP2002240003A
Authority: JP
Inventors: Katsuzo Kawanishi; 川西　勝三
Original assignee: Yamato Scale Co Ltd
Current assignee: Yamato Scale Co Ltd
Priority date: 2002-08-21
Filing date: 2002-08-21
Publication date: 2004-03-11
Anticipated expiration: 2022-08-21
Also published as: JP4097483B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal detecting device for monitoring a detecting sensitivity by displaying a deviation of a metal detecting signal from a reference value while reporting an abnormality of the metal detecting sensitivity using a specimen of metal foreign matter. <P>SOLUTION: The metal detecting device is provided with a transmitter coil generating an alternating magnetic field; a plurality of receiving coils arranged in the magnetic field generated by the transmitter coil; a deviation of metal detecting signal processing means processing the deviation of the metal detecting signal from an amplitude of the metal detecting signal obtained when the specimen of the foreign matter is passing through the magnetic field based on the previously determined reference value for deviation processing for the metal detecting signal; a determination means for proper deviation of the metal detecting signal comparing the deviation of the metal detecting signal and a previously determined reference value for the proper deviation; and an abnormality reporting means reporting the abnormality of the metal detecting sensitivity based on the determination of the determination means for proper deviation of the metal detecting signal. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、被検査物に含まれる金属異物の検出を行う金属検出装置の検出感度の異常及び零バランス異常の報知手段に関する。
【０００２】
【従来の技術】
従来から、食品や医薬品に混入する金属異物（鉄、ステンレススチ−ル等）の検出に、金属検出装置が用いられている。また、前記金属検出装置は、被検査物を移動させる移動通路と、前記通路の周囲に形成された金属検出コイルを備えており、金属異物が混入した被検査物が、前記移動通路を通過するときに発生する磁気的変化に基づいて、前記被検査物に混入する金属異物の検出を行うものである。
また、前記金属異物が混入した被検査物が、前記移動通路を通過するときに、金属検出用コイルから出力される検出信号は、増幅部により増幅され、さらにフィルタ−を通ってノイズが除去された後、比較部において基準値と比較されることで、前記被検査物に混入する金属異物の金属検出判定が行われている。
【０００３】
従来の金属検出装置では、その使用に際して、検出コイルの出力に発生する不平衡出力の調整を行うと共に、予め被検査物や検出する金属異物の種類に応じて、その検出感度を校正している。前記検出感度の校正方法として、例えば金属異物試料を混入しない被検査物と金属異物試料を混入した被検査物を用意して、それぞれ前記金属検出装置に通して、その感度校正を行う方法がある。この場合、被検査物に金属異物試料があるときの金属検出判定結果と、金属異物試料がないときの金属検出判定結果とに基づいて感度校正がされている。すなわち、金属異物試料があるときに金属異物が検出され、金属異物試料がないときに金属異物が検出されないように、金属検出判定のための基準値を設定している。
【０００４】
しかしながら、前記金属検出装置では、使用中においても金属検出コイルの発振周波数の変動、その他により、金属検出感度の変動が生じることがある。また、長期的には発振コイル及び受信コイルの機械的歪みや、温度変化等に伴う回路素子の特性変化により受信コイルの出力の平衡がくずれ、金属異物が存在しなくても不平衡出力が生じることになり、これによって金属異物の検出感度が低下する。したがって、金属異物の検出感度を維持させるためには、使用前における受信コイルの不平衡出力の調整と金属検出の感度校正に加えて、使用状態の途中において金属異物試料を混入した被検査物を金属検出装置に通して、その感度校正を行っている。
【０００５】
【発明が解決しようとする課題】
前述したように、従来の金属検出装置では、例えば金属異物試料を混入しない被検査物と、金属異物試料を混入した被検査物とを用いて検出した、それぞれの金属判定結果に基づいて金属検出判定基準値を設定しているので、このような方法では必ずしも正確な設定が行われない。また、使用に際して、予め金属異物試料を用いて金属検出判定基準値を設定していても、金属異物試料による金属検出信号振幅値と前記金属検出判定基準値との偏差が所定の値であるかどうかの確認を正確に行うことができない。したがって、例えば定期的に実施される金属異物試料を用いた感度チェックまたは感度校正作業毎の間において、金属検出感度が低下して金属異物試料と同等もしくは大きいサイズの金属異物が被検査物に混入されていても検出されない、いわゆる検出不良が生じることになる。このように従来の金属検出装置では、金属検出感度が変動したときに発生する検出不良を未然に防ぐことができない。そこで、金属検出の検出感度を維持するためには、検出感度のチェックまたは校正を頻繁に行う必要があるが、作業効率が低下することによる運用面での問題が残ることになる。
【０００６】
そこで、本発明は、このような従来技術の問題点を解決し、金属異物試料による金属検出信号振幅値と金属検出信号偏差値算出基準値との偏差が、金属検出判定が適正にされる範囲内の値であるかどうかの確認を正確に行うことで、金属検出感度の低下に伴い発生する検出不良を未然に防ぐことができる金属検出装置を提供することを目的とする。
【０００７】
【課題を解決するための手段】
交番磁界を発生させる送信コイルと、該送信コイルにより発生する磁界中に配置された複数の受信コイルとを備え、前記磁界中を通過する被検査物に混入する金属異物の検出を行う金属検出装置において、金属異物試料を前記磁界中に通過させたときに発生する金属検出信号振幅値と予め設定された基準値に基づいて前記金属検出信号振幅値の偏差値を演算する演算手段と、前記金属検出信号振幅値の偏差値が所定の範囲内にないときに金属検出感度の異常を報知する金属検出感度異常報知手段とを備えたことを特徴とする（請求項１）。
【０００８】
これにより、金属異物試料による検出信号振幅値と予め設定された基準値との偏差が、適正範囲内の値でないときに金属検出感度異常の報知が出力されるので、金属検出感度の低下を早期に発見でき、これに伴い発生する検出不良を未然に防ぐことが可能となる。
【０００９】
また、交番磁界を発生させる送信コイルと、該送信コイルにより発生する磁界中に配置された複数の受信コイルとを備え、前記磁界中を通過する被検査物に混入する金属異物の検出を行う金属検出装置において、金属異物試料を前記磁界中に通過させたときに発生する金属検出信号振幅値と予め設定された金属検出信号偏差値算出基準値に基づいて金属検出信号偏差値を求める金属検出信号偏差値算出手段と、前記金属検出信号偏差値と予め設定された金属検出信号適正偏差値判定基準値とを比較判定する金属検出信号適正偏差値判定手段と、前記金属検出信号適正偏差値判定手段の判定結果に基づき金属検出感度異常を報知する金属検出感度異常報知手段とを備えたことを特徴とする（請求項２）。
【００１０】
これにより、金属検出信号適正偏差値判定手段を備えることで、金属異物試料による検出信号振幅値と予め設定された基準値との偏差が、適正範囲内の値でないときに金属検出感度異常の報知が出力されるので、金属検出感度の低下を早期に発見でき、これに伴い発生する検出不良を未然に防ぐことが可能となる。
【００１１】
そして、交番磁界を発生させる送信コイルと、該送信コイルにより発生する磁界中に配置された複数の受信コイルとを備え、前記磁界中を通過する被検査物に混入する金属異物の検出を行う請求項１または２のいずれかに記載の金属検出装置において、金属異物試料を前記磁界中に通過させたときに発生する金属検出信号振幅値と予め設定された金属検出信号偏差値算出基準値に基づいて演算された前記金属検出信号振幅値の偏差値を表示する金属検出信号偏差値表示手段とを備えたことを特徴とする。（請求項３）。
【００１２】
これによって、金属異物試料による金属検出信号振幅値と予め設定された金属検出信号偏差値算出基準値との偏差値が表示されることで、該偏差値が前記金属検出判定が適正にされる範囲内の値であるかどうかの確認を正確に行うことができ、金属検出感度の低下に伴い発生する検出不良を未然に防ぐことができる。
【００１３】
さらに、交番磁界を発生させる送信コイルと、該送信コイルにより発生する磁界中に配置された複数の受信コイルとを備え、前記磁界中を通過する被検査物に混入する金属異物の検出を行う請求項１乃至３のいずれかに記載の金属検出装置において、金属異物を前記磁界中に通過させない状態での前記受信コイルの不平衡出力の振幅値と予め設定された平衡状態判定のための適正不平衡出力判定基準値とを比較判定する適正不平衡出力判定手段と、前記適正不平衡出力判定手段による判定結果に基づいて、前記受信コイルの不平衡出力の振幅値が所定の範囲内にないときに零バランス異常を報知する零バランス異常報知手段とを、さらに備えたことを特徴とする（請求項４）。
【００１４】
これによって、金属異物試料による検出信号振幅値と前記適正不平衡出力判定基準値との偏差が、検出判定が適正にされる範囲内の値でないときに金属検出感度異常が出力されると共に、受信コイルの不平衡出力の振幅値が所定の範囲内にないときにも零バランス異常が報知されるので、より正確に金属検出感度の低下を早期に発見でき、これに伴い発生する検出不良を未然に防ぐことが可能となる。
【００１５】
また、交番磁界を発生させる送信コイルと、該送信コイルにより発生する磁界中に配置された複数の受信コイルとを備え、前記磁界中を通過する被検査物に混入する金属異物の検出を行う請求項４に記載の金属検出装置において、金属異物試料を前記磁界中に通過させたときに発生する金属検出信号振幅値と、予め設定された金属検出信号偏差値算出基準値に基づいて演算された前記金属検出信号振幅値の偏差値を表示する金属検出信号偏差値表示手段を備えると共に、さらに金属異物を前記磁界中に通過させない状態での前記受信コイルの不平衡出力の振幅値を表示する不平衡出力表示手段とを備えたことを特徴とする（請求項５）。
【００１６】
これにより、金属異物試料による検出信号振幅値と前記金属検出信号偏差値算出基準値との偏差値と、受信コイルの不平衡出力の振幅値が同時に表示されるので、より正確に金属検出感度の低下を早期に発見でき、これに伴い発生する検出不良を未然に防ぐことが可能となる。
【００１７】
【発明の実施の形態】
次に、添付図面に基づいて、本発明の実施の形態についてより詳細に説明する。
【００１８】
図１は、本発明の実施の形態の構成図を示す。図１において、１は本発明の実施の形態の金属検出装置における金属検出部である。金属検出部１には図示しない被検査物を通過させるための通路と、この通路を囲むように送信コイルと一対の受信コイルが配置されている。また、前記送信コイルには、高周波電流が供給され交番磁界を発生させることで、前記送信コイルに対向する位置に配置された一対の受信コイルに誘起電圧出力が生じる。前記一対の受信コイルの出力は差動増幅回路に入力され、前記磁界中に金属が存在しないときは、前記一対の受信コイルのそれぞれの出力電圧は同一となるため、前記差動増幅回路の不平衡出力は零となってバランスがとれた状態となる。さらに、前記差動増幅回路の出力信号は検波回路部及びフィルタを通ってＡ／Ｄ変換部でＡ／Ｄ変換され、デジタル信号として金属検出部１から出力される。
【００１９】
つづいて、金属検出部１の出力信号は切り替えスイッチ２と後に説明する零バランス異常判定回路の不平衡出力検出部１３に接続される。前記スイッチ２により、金属検出部１の出力信号を後に説明する金属検出報知回路部または金属検出感度異常報知回路部のいずれかに選択して切り替え接続することができる。まず、通常の金属検出装置の使用時に選択される前記金属検出報知回路部について説明すると、金属検出判定部４に入力された金属検出部の出力信号は、従来の金属検出装置に備えられているように、金属検出判定基準値設定部３で設定記憶された金属検出判定基準値と比較され、金属検出の判定が行われる。本発明の金属検出装置の通路内を通過する被検査物に金属異物が混入されていると、前記金属検出部１の一対の受信コイルにおける誘起電圧出力信号の位相及び振幅が変化して、不平衡出力信号が生じる。したがって、この場合、前記不平衡出力信号と前記金属検出判定基準値とが比較判定され、前記不平衡出力信号の振幅値が前記金属検出判定基準値を越える場合に金属検出判定信号が出力される。
【００２０】
通常、前記金属検出判定基準値は、被検査物に混入する金属異物について、許容できない大きさのもので検出可能な最小のものが検出されるように予め設定されると共に、前記最小の大きさの金属異物試料を通過させたときの金属検出信号の振幅値が、前記金属検出判定基準値に対して若干大きい値となるように前記金属検出部の増幅回路において感度調整を行っている。例えば、金属検出判定基準値を３．０Ｖとして、検出可能な最小の前記金属異物試料を通過させたときの金属検出信号の振幅値が３．２Ｖになるように、前記感度調整が行われる。さらに、前記金属検出判定信号に基づいて、金属検出報知部５では、例えばランプを設けることでランプ表示することや、ブザ−を設けることでブザ−を鳴らすようにすることができ、表示部を設けることで金属有等のメッセ−ジを表示してもよい。また、金属検出の判定時に金属検出信号の振幅値を表示部６において表示することができる。
【００２１】
また、本発明の実施の形態の金属検出装置では、切り替えスイッチ２を金属検出信号偏差値異常報知回路部に選択することにより、検出感度の調整、即ち感度校正に用いられる金属異物試料を金属検出装置の通路に通したときに検出される金属検出信号の振幅値と基準値との偏差値が適正範囲内であるかどうかを判定することができる。前記金属検出感度異常報知回路部では、まず、金属検出部１の出力信号が金属検出信号偏差値検出部８に入力される。つぎに、金属検出信号偏差値検出部８において、前記金属検出部１の出力信号は金属検出信号偏差値算出基準値設定部７で設定記憶された金属検出信号偏差値算出基準値と比較され、前記金属検出信号偏差値算出基準値との偏差値が演算され、さらにこの偏差値が金属検出信号適正偏差値判定部１０に入力される。
【００２２】
また、前記金属検出偏差値は、金属検出信号適正偏差値判定部１０において、適正偏差値判定基準値設定部９で設定記憶された適正偏差値判定基準値と比較され、適正な範囲内の値かどうかの判定が行われ、判定信号が出力される。ここで、例えば、前記金属検出信号偏差値算出基準値は予め３．０Ｖに設定されると共に、前記適正偏差値判定基準値は、予め適正範囲の上下限値として、それぞれ０．３Ｖ及び０．２Ｖに設定される。この場合、前記金属検出信号の振幅値が３．２Ｖ〜３．３Ｖの範囲内にあれば、適正値と判定される。さらに、前記判定信号は金属検出感度異常報知部１１に入力され、ランプ表示手段、ブザ−等の報知手段を設けることによって異常を報知することができ、表示部を設けることで偏差値異常のメッセ−ジを表示してもよい。また、金属検出信号偏差値検出部８から出力される前記金属検出信号偏差値検出基準値との偏差値を表示部１２において表示することができる。
【００２３】
これらの構成により、金属異物試料による検出信号振幅値と前記基準値との偏差値が、検出判定が適正にされる範囲内の値でない場合に金属検出感度異常が報知されると共に、前記偏差値が表示されるので、金属検出装置の金属検出感度が適正に維持されていることのチェックを正確に行うことで、金属検出感度の低下を早期に発見でき、これに伴い発生する検出不良を未然に防ぐことが可能となる。また、前記金属検出報知回路部における金属検出判定基準値と、前記金属検出信号偏差値異常報知回路部における金属検出信号偏差値算出基準値とを同じ値で設定される場合には、金属検出判定基準値設定部３と金属検出信号偏差値算出基準値設定部７を共通のものとしてもよい。
【００２４】
次に金属検出部１から出力された信号は、不平衡出力検出部１３に入力される。不平衡出力検出部１３では、数十秒の時定数を有するデジタルフィルタ−の処理がされることで、入力された信号のうち、受信コイルの出力信号における零バランスの長期的変動のような、定常的な出力信号の振幅成分のみが抽出される。また、前記不平衡出力検出部１３の出力信号は不平衡出力異常判定部１５に入力され、ここで不平衡出力異常判定基準値設定部１４において、不平衡出力の許容値として設定されている不平衡出力異常判定基準値と比較され、前記出力信号が許容される範囲内にあるかどうかの判定が行われる。ここで、前記不平衡出力異常判定基準値としては、例えば０．２Ｖに設定される。
【００２５】
さらに、前記不平衡出力異常判定部１５の判定結果は零バランス異常報知部１６に入力され、ランプ表示手段、ブザ−等の報知手段を設けることによって零バランス異常を報知することができ、表示部を設けることで零バランス異常のメッセ−ジを表示してもよい。また、不平衡出力検出部１３から出力される不平衡出力振幅値を不平衡出力値表示部１７において表示することができる。これによって、受信コイルの不平衡出力の振幅値が所定の範囲内にない場合に、零バランス異常が報知されると共に、前記不平衡出力の振幅値が表示されるので、零バランスの変動のチェックを正確に行うことで、金属検出感度の低下を早期に発見でき、これに伴い発生する検出不良を未然に防ぐことが可能となる。
【００２６】
【発明の効果】
以上のように、本発明によれば、金属検出装置において、金属異物試料による検出信号振幅値と前記基準値との偏差が、検出判定が適正にされる範囲内の値でない場合に金属検出感度異常が報知されると共に、受信コイルの不平衡出力の振幅値が所定の範囲内にないときにも零バランス異常が報知されるので、より正確に金属検出感度の低下を早期に発見でき、これに伴い発生する検出不良を未然に防ぐことが可能である。
【図面の簡単な説明】
【図１】本発明の金属検出装置の構成図である。
【付号の説明】
１　　金属検出部
２　　切り替えスイッチ
３　　金属検出判定基準値設定部
４　　金属検出判定部
５　　金属検出報知部
６　　金属検出信号振幅値表示部
７　　金属検出信号偏差値算出基準値設定部
８　　金属検出信号偏差値検出部
９　　金属検出信号適正偏差値判定基準値設定部
１０　　金属検出信号適正偏差値判定部
１１　　金属検出感度異常報知部
１２　　　金属検出信号偏差値表示部
１３　　不平衡出力検出部
１４　　不平衡出力異常判定基準値設定部
１５　　不平衡出力異常判定部
１６　　零バランス異常報知部
１７　　不平衡出力値表示部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a means for notifying a detection sensitivity abnormality and a zero balance abnormality of a metal detection device for detecting a metal foreign substance contained in an inspection object.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a metal detector has been used for detecting a metallic foreign substance (iron, stainless steel, or the like) mixed in a food or medicine. Further, the metal detection device includes a movement path for moving the inspection object, and a metal detection coil formed around the passage, and the inspection object mixed with the metal foreign matter passes through the movement path. The detection of the metallic foreign matter mixed into the inspection object is performed based on the magnetic change that sometimes occurs.
Further, when the inspection object mixed with the metal foreign matter passes through the moving passage, the detection signal output from the metal detection coil is amplified by an amplification unit, and further, the noise is removed through a filter. After that, the comparison unit compares the reference value with the reference value, thereby performing metal detection determination of the metal foreign matter mixed into the inspection object.
[0003]
In the conventional metal detection device, when used, the unbalanced output generated in the output of the detection coil is adjusted, and the detection sensitivity is calibrated in advance according to the type of the object to be inspected and the foreign metal to be detected. . As a method of calibrating the detection sensitivity, for example, there is a method of preparing an inspection object in which a metal foreign substance sample is not mixed and an inspection object in which a metal foreign substance sample is mixed, and passing the inspection object through the metal detection device to calibrate the sensitivity. . In this case, the sensitivity is calibrated based on the metal detection determination result when there is a metal foreign matter sample in the inspection object and the metal detection determination result when there is no metal foreign matter sample. That is, a reference value for metal detection determination is set so that a metal foreign substance is detected when there is a metal foreign substance sample and a metal foreign substance is not detected when there is no metal foreign substance sample.
[0004]
However, in the metal detection device, even during use, the oscillation frequency of the metal detection coil may fluctuate, and the metal detection sensitivity may fluctuate. Further, in the long term, the output of the receiving coil is debalanced due to the mechanical distortion of the oscillation coil and the receiving coil and the characteristic change of the circuit element due to the temperature change and the like, and an unbalanced output is generated even if there is no metal foreign matter. As a result, the sensitivity of detecting foreign metal particles is reduced. Therefore, in order to maintain the detection sensitivity of metal foreign matter, in addition to adjusting the unbalanced output of the receiving coil and calibrating the sensitivity of metal detection before use, the inspection object mixed with the metal foreign matter sample during use is required. The sensitivity is calibrated through a metal detector.
[0005]
[Problems to be solved by the invention]
As described above, in the conventional metal detection apparatus, for example, a metal detection is performed based on the metal determination result detected using the test object in which the metal foreign substance sample is not mixed and the test object in which the metal foreign substance sample is mixed. Since the judgment reference value is set, accurate setting is not always performed by such a method. In use, even if the metal detection determination reference value is set in advance using a metal foreign matter sample, whether the deviation between the metal detection signal amplitude value of the metal foreign matter sample and the metal detection determination reference value is a predetermined value. It is not possible to accurately confirm whether or not. Therefore, for example, during the sensitivity check or sensitivity calibration using a metal foreign matter sample that is periodically performed, the metal detection sensitivity is reduced, and metal foreign matter having a size equal to or larger than the metal foreign matter sample is mixed into the inspection object. Even if they are detected, they are not detected, that is, a so-called detection failure occurs. As described above, in the conventional metal detection device, it is not possible to prevent a detection failure that occurs when the metal detection sensitivity fluctuates. Therefore, in order to maintain the detection sensitivity of metal detection, it is necessary to frequently check or calibrate the detection sensitivity, but there remains an operational problem due to a reduction in work efficiency.
[0006]
Therefore, the present invention solves such a problem of the related art, and the deviation between the metal detection signal amplitude value and the metal detection signal deviation value calculation reference value due to the metal foreign matter sample is within a range in which the metal detection determination is properly performed. It is an object of the present invention to provide a metal detection device capable of preventing a detection failure caused by a decrease in metal detection sensitivity by accurately confirming whether the value is within the range.
[0007]
[Means for Solving the Problems]
A metal detection device that includes a transmission coil that generates an alternating magnetic field, and a plurality of reception coils that are arranged in a magnetic field generated by the transmission coil, and that detects a metal foreign substance mixed in an inspection object that passes through the magnetic field. A calculating means for calculating a deviation value of the metal detection signal amplitude value based on a metal detection signal amplitude value generated when the metal foreign matter sample is passed through the magnetic field and a preset reference value; and Metal detection sensitivity abnormality notification means for notifying an abnormality of the metal detection sensitivity when the deviation value of the detection signal amplitude value is not within a predetermined range (claim 1).
[0008]
Accordingly, when the deviation between the detection signal amplitude value due to the metal foreign matter sample and the preset reference value is not a value within the appropriate range, the notification of the metal detection sensitivity abnormality is output. , And it is possible to prevent the detection failure that occurs with it.
[0009]
Further, a metal that includes a transmitting coil that generates an alternating magnetic field, and a plurality of receiving coils that are arranged in a magnetic field generated by the transmitting coil, and that detects a metal foreign substance mixed in an inspection object that passes through the magnetic field. In the detection device, a metal detection signal for obtaining a metal detection signal deviation value based on a metal detection signal amplitude value generated when a metal foreign matter sample is passed through the magnetic field and a predetermined metal detection signal deviation value calculation reference value. Deviation value calculation means, metal detection signal proper deviation value judgment means for comparing the metal detection signal deviation value with a preset metal detection signal proper deviation value judgment reference value, and said metal detection signal proper deviation value judgment means And a metal detection sensitivity abnormality notifying means for notifying the metal detection sensitivity abnormality based on the determination result.
[0010]
Thus, the provision of the metal detection signal proper deviation value determination means enables the notification of the metal detection sensitivity abnormality when the deviation between the detection signal amplitude value due to the metal foreign matter sample and the preset reference value is not within a proper range. Is output, a decrease in metal detection sensitivity can be detected at an early stage, and it is possible to prevent a detection failure caused by this from occurring.
[0011]
And a transmitting coil for generating an alternating magnetic field, and a plurality of receiving coils arranged in a magnetic field generated by the transmitting coil, for detecting a metallic foreign substance mixed in the inspection object passing through the magnetic field. Item 3. The metal detection device according to any one of Items 1 or 2, wherein a metal foreign matter sample is caused to pass through the magnetic field, and a metal detection signal amplitude value generated based on the metal detection signal deviation value calculation reference value is set in advance. A metal detection signal deviation value display means for displaying a deviation value of the metal detection signal amplitude value calculated by the above. (Claim 3).
[0012]
Accordingly, a deviation value between the metal detection signal amplitude value of the metal foreign material sample and a preset metal detection signal deviation value calculation reference value is displayed, and the deviation value is set in a range where the metal detection determination is appropriate. It is possible to accurately confirm whether the value is within the range, and it is possible to prevent a detection failure that occurs due to a decrease in metal detection sensitivity.
[0013]
Further, a transmission coil for generating an alternating magnetic field, and a plurality of reception coils arranged in a magnetic field generated by the transmission coil, for detecting a metal foreign substance mixed in an inspection object passing through the magnetic field. Item 4. In the metal detection device according to any one of Items 1 to 3, the amplitude value of the unbalanced output of the receiving coil in a state where the metal foreign matter is not allowed to pass through the magnetic field and a predetermined inappropriate value for determining the balanced state. A proper unbalanced output judging means for comparing and judging a balanced output judgment reference value, based on a judgment result by the proper unbalanced output judging means, when an amplitude value of the unbalanced output of the receiving coil is not within a predetermined range. And zero balance abnormality notifying means for notifying zero balance abnormality.
[0014]
Accordingly, when the deviation between the detection signal amplitude value due to the metallic foreign matter sample and the appropriate unbalanced output determination reference value is not a value within the range where the detection determination is appropriate, the metal detection sensitivity abnormality is output and the reception is performed. Even when the amplitude value of the unbalanced output of the coil is not within the predetermined range, the zero balance abnormality is notified, so that a decrease in metal detection sensitivity can be detected more accurately at an early stage, and the detection failure caused by this can be detected beforehand. Can be prevented.
[0015]
Further, a transmission coil for generating an alternating magnetic field, and a plurality of reception coils disposed in a magnetic field generated by the transmission coil, for detecting a metal foreign substance mixed in an inspection object passing through the magnetic field. Item 4. In the metal detection device according to Item 4, the calculation is performed based on a metal detection signal amplitude value generated when a metal foreign matter sample is passed through the magnetic field and a preset metal detection signal deviation value calculation reference value. A metal detection signal deviation value display means for displaying a deviation value of the metal detection signal amplitude value is provided, and further, an amplitude value of an unbalanced output of the receiving coil in a state where metal foreign matter is not allowed to pass through the magnetic field is displayed. A balance output display means is provided (claim 5).
[0016]
Thereby, the deviation value between the detection signal amplitude value due to the metal foreign matter sample and the metal detection signal deviation value calculation reference value and the amplitude value of the unbalanced output of the receiving coil are simultaneously displayed, so that the metal detection sensitivity can be more accurately detected. It is possible to detect the deterioration at an early stage, and to prevent a detection failure caused by the deterioration in advance.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described in more detail with reference to the accompanying drawings.
[0018]
FIG. 1 shows a configuration diagram of an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a metal detection unit in the metal detection device according to the embodiment of the present invention. The metal detector 1 is provided with a passage through which a test object (not shown) passes, and a transmission coil and a pair of reception coils surrounding the passage. In addition, a high-frequency current is supplied to the transmission coil to generate an alternating magnetic field, so that an induced voltage output is generated in a pair of reception coils disposed at a position facing the transmission coil. The outputs of the pair of receiving coils are input to a differential amplifier circuit. When no metal is present in the magnetic field, the output voltages of the pair of receiving coils are the same, so that the differential amplifier circuit has The balanced output becomes zero and a balanced state is obtained. Further, the output signal of the differential amplifier circuit is A / D-converted by an A / D converter through a detection circuit and a filter, and is output from the metal detector 1 as a digital signal.
[0019]
Subsequently, the output signal of the metal detector 1 is connected to the changeover switch 2 and the unbalanced output detector 13 of the zero balance abnormality determination circuit described later. By the switch 2, the output signal of the metal detection unit 1 can be selectively connected to either a metal detection notification circuit unit or a metal detection sensitivity abnormality notification circuit unit to be described later. First, a description will be given of the metal detection notification circuit section selected when a normal metal detection apparatus is used. The output signal of the metal detection section input to the metal detection determination section 4 is provided in the conventional metal detection apparatus. Thus, the metal detection determination reference value set and stored in the metal detection determination reference value setting unit 3 is compared with the metal detection determination reference value, and the determination of metal detection is performed. If a metal foreign object is mixed in the inspection object passing through the passage of the metal detection device of the present invention, the phase and amplitude of the induced voltage output signal in the pair of receiving coils of the metal detection unit 1 change, and A balanced output signal results. Therefore, in this case, the unbalanced output signal is compared with the metal detection determination reference value, and a metal detection determination signal is output when the amplitude value of the unbalanced output signal exceeds the metal detection determination reference value. .
[0020]
Usually, the metal detection criterion value is set in advance such that the smallest detectable metal foreign matter mixed into the inspection object is unacceptable and has the minimum size. The sensitivity adjustment is performed in the amplifier circuit of the metal detection unit such that the amplitude value of the metal detection signal when passing through the metal foreign matter sample becomes slightly larger than the metal detection determination reference value. For example, the sensitivity adjustment is performed such that the metal detection determination reference value is 3.0 V and the amplitude of the metal detection signal when passing the minimum detectable metal foreign matter sample is 3.2 V. Further, based on the metal detection determination signal, the metal detection notifying section 5 can display a lamp by providing a lamp or sound a buzzer by providing a buzzer, for example. By providing such a message, a message such as the presence of metal may be displayed. In addition, the amplitude value of the metal detection signal can be displayed on the display unit 6 at the time of metal detection determination.
[0021]
Further, in the metal detection device according to the embodiment of the present invention, by selecting the changeover switch 2 as the metal detection signal deviation value abnormality notification circuit section, the detection sensitivity is adjusted, that is, the metal foreign matter sample used for the sensitivity calibration is detected by the metal detection. It can be determined whether or not a deviation value between the amplitude value of the metal detection signal detected when passing through the passage of the device and the reference value is within an appropriate range. In the metal detection sensitivity abnormality notification circuit section, first, the output signal of the metal detection section 1 is input to the metal detection signal deviation value detection section 8. Next, in the metal detection signal deviation value detection unit 8, the output signal of the metal detection unit 1 is compared with the metal detection signal deviation value calculation reference value set and stored in the metal detection signal deviation value calculation reference value setting unit 7, A deviation value from the metal detection signal deviation value calculation reference value is calculated, and this deviation value is input to the metal detection signal appropriate deviation value determination unit 10.
[0022]
The metal detection deviation value is compared with an appropriate deviation value determination reference value set and stored in an appropriate deviation value determination reference value setting unit 9 by a metal detection signal appropriate deviation value determination unit 10 and a value within an appropriate range is determined. Is determined, and a determination signal is output. Here, for example, the metal detection signal deviation value calculation reference value is set to 3.0 V in advance, and the appropriate deviation value determination reference value is 0.3 V and 0. Set to 2V. In this case, if the amplitude value of the metal detection signal is in the range of 3.2 V to 3.3 V, it is determined that the value is appropriate. Further, the judgment signal is input to the metal detection sensitivity abnormality notifying section 11, and the abnormality can be notified by providing a notifying means such as a lamp display means and a buzzer. -May be displayed. Further, a deviation value from the metal detection signal deviation value detection reference value output from the metal detection signal deviation value detection unit 8 can be displayed on the display unit 12.
[0023]
According to these configurations, when the deviation value between the detection signal amplitude value and the reference value due to the metal foreign matter sample is not a value within the range in which the detection determination is appropriate, the metal detection sensitivity abnormality is notified and the deviation value is notified. Is displayed.By accurately checking that the metal detection sensitivity of the metal detection device is properly maintained, a drop in the metal detection sensitivity can be found at an early stage, and the detection failure that occurs with this can be detected beforehand. Can be prevented. In addition, when the metal detection determination reference value in the metal detection notification circuit unit and the metal detection signal deviation value calculation reference value in the metal detection signal deviation value abnormality notification circuit unit are set to the same value, the metal detection determination The reference value setting unit 3 and the metal detection signal deviation value calculation reference value setting unit 7 may be shared.
[0024]
Next, the signal output from the metal detector 1 is input to the unbalanced output detector 13. In the unbalanced output detection unit 13, a digital filter having a time constant of several tens of seconds is processed so that, among the input signals, a long-term fluctuation of zero balance in the output signal of the receiving coil can be obtained. Only stationary output signal amplitude components are extracted. The output signal of the unbalanced output detection unit 13 is input to an unbalanced output abnormality determination unit 15, where the unbalanced output abnormality determination reference value setting unit 14 sets an unbalanced output allowable value. A comparison is made with a reference value for determining whether or not the output is abnormal, and it is determined whether the output signal is within an allowable range. Here, the unbalanced output abnormality determination reference value is set to, for example, 0.2V.
[0025]
Further, the determination result of the unbalanced output abnormality determination unit 15 is input to a zero balance abnormality notification unit 16, and the zero balance abnormality can be notified by providing a notification unit such as a lamp display unit and a buzzer. May be displayed to display a message indicating a zero balance abnormality. Further, the unbalanced output amplitude value output from the unbalanced output detection unit 13 can be displayed on the unbalanced output value display unit 17. Thereby, when the amplitude value of the unbalanced output of the receiving coil is not within the predetermined range, the zero balance abnormality is notified and the amplitude value of the unbalanced output is displayed, so that the fluctuation of the zero balance can be checked. By accurately performing the detection, it is possible to detect a drop in the metal detection sensitivity at an early stage, and it is possible to prevent a detection failure caused by the detection.
[0026]
【The invention's effect】
As described above, according to the present invention, in the metal detection device, when the deviation between the detection signal amplitude value due to the metal foreign matter sample and the reference value is not a value within the range where the detection determination is appropriate, the metal detection sensitivity is An abnormality is reported, and even when the amplitude value of the unbalanced output of the receiving coil is not within the predetermined range, a zero balance abnormality is reported. It is possible to prevent a detection failure caused by the above.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a metal detection device of the present invention.
[Description of numbering]
Reference Signs List 1 metal detection unit 2 changeover switch 3 metal detection judgment reference value setting unit 4 metal detection judgment unit 5 metal detection notification unit 6 metal detection signal amplitude value display unit 7 metal detection signal deviation value calculation reference value setting unit 8 metal detection signal deviation value Detection unit 9 Metal detection signal proper deviation value judgment reference value setting unit 10 Metal detection signal proper deviation value judgment unit 11 Metal detection sensitivity abnormality notification unit 12 Metal detection signal deviation value display unit 13 Unbalanced output detection unit 14 Unbalanced output abnormality judgment Reference value setting unit 15 Unbalanced output abnormality determination unit 16 Zero balance abnormality notification unit 17 Unbalanced output value display unit

Claims

A metal detection device that includes a transmission coil that generates an alternating magnetic field, and a plurality of reception coils that are arranged in a magnetic field generated by the transmission coil, and that detects a metal foreign substance mixed in an inspection object that passes through the magnetic field. Computing means for computing a deviation value of the metal detection signal amplitude value based on a metal detection signal amplitude value generated when a metal foreign matter sample is passed through the magnetic field and a preset reference value; and A metal detection device comprising: a metal detection sensitivity abnormality notification unit that notifies an abnormality in metal detection sensitivity when a deviation value of a detection signal amplitude value is not within a predetermined range.

A metal detection device that includes a transmission coil that generates an alternating magnetic field, and a plurality of reception coils that are arranged in a magnetic field generated by the transmission coil, and that detects a metal foreign substance mixed in an inspection object that passes through the magnetic field. In the metal detection signal deviation value to obtain a metal detection signal deviation value based on a metal detection signal amplitude value generated when a metal foreign matter sample is passed through the magnetic field and a predetermined metal detection signal deviation value calculation reference value Calculation means; metal detection signal appropriate deviation value determination means for comparing the metal detection signal deviation value with a preset metal detection signal appropriate deviation value determination reference value; and determination by the metal detection signal appropriate deviation value determination means. A metal detection device comprising: a metal detection sensitivity abnormality notification unit that notifies a metal detection sensitivity abnormality based on a result.

A metal detection device that includes a transmission coil that generates an alternating magnetic field, and a plurality of reception coils that are arranged in a magnetic field generated by the transmission coil, and that detects a metal foreign substance mixed in an inspection object that passes through the magnetic field. The deviation value of the metal detection signal amplitude value calculated based on the metal detection signal amplitude value generated when the metal foreign matter sample is passed through the magnetic field and a predetermined metal detection signal deviation value calculation reference value 3. A metal detection device according to claim 1, further comprising: a metal detection signal deviation value display means for displaying the following.

A metal detection device that includes a transmission coil that generates an alternating magnetic field, and a plurality of reception coils that are arranged in a magnetic field generated by the transmission coil, and that detects a metal foreign substance mixed in an inspection object that passes through the magnetic field. A proper unbalance that compares and compares an amplitude value of the unbalanced output of the receiving coil in a state where metal foreign matter is not allowed to pass through the magnetic field with a preset appropriate unbalanced output determination reference value for determining a balanced state. Output determination means, and zero balance abnormality notification means for reporting a zero balance abnormality when the amplitude value of the unbalanced output of the receiving coil is not within a predetermined range, based on a determination result by the appropriate unbalanced output determination means. The metal detection device according to any one of claims 1 to 3, further comprising:

A metal detection device that includes a transmission coil that generates an alternating magnetic field, and a plurality of reception coils that are arranged in a magnetic field generated by the transmission coil, and that detects a metal foreign substance mixed in an inspection object that passes through the magnetic field. In the above, a metal detection signal amplitude value generated when a metal foreign matter sample is passed through the magnetic field, and a deviation of the metal detection signal amplitude value calculated based on a predetermined metal detection signal deviation value calculation reference value A metal detection signal deviation value display means for displaying a value, and an unbalanced output display means for displaying an amplitude value of an unbalanced output of the receiving coil in a state where metal foreign matter is not allowed to pass through the magnetic field. The metal detection device according to claim 4, wherein: