JP3908473B2 - Metal piece identification device made of multiple materials - Google Patents

Description

そして、磁束密度をＤ、誘電率をεとすると、下記数２が成り立つ。
【００２１】
【数２】

そして、下記数３が成り立ち、ｉ＝σＥ，Ｄ＝εＥであるので、数３は数４となる。
【００２２】
【数３】

【数４】

よって、下記数５が成り立つ。
【００２３】
【数５】

上記数１及び数５より磁界Ｈを消去し、電界Ｅの式とすると下記数６が成り立つ。
【００２４】
【数６】

次に電界Ｅを消去し、磁界Ｈの式とすると下記数７が成り立つ。
【００２５】
【数７】

ここで、Ｅ∝ｅ^ｊωｔ（ただし、ω＝２πｆ）とおいて、下記数８と減衰振動の式となる。
【００２６】
【数８】

一般的な非磁性金属の場合、ε≒ε_０＝８．８５４２×１０^−１２Ｆ／ｍであるので、σ＝１／ρ≒１／１０^−８〜１０^−７となり、εω／σ≒１０^−１８程度である。また、ω^２εμはωが非常に大きくならない限り、ｊωσμに比べ無視できるので，下記数９と表わすことができる。
【００２７】
【数９】

これより、下記数１０となり、δは表皮効果の深さを示す。
【００２８】
【数１０】

また、数１１となり、表面からｚ＝δの深さで、電界Ｅは１／ｅに減衰する。
【００２９】
【数１１】

ここで、ｚ＝０において、Ｅ＝Ｅ_０であるときＡ＝Ｅ_０とおいて、上記数１１は数１２となる。
【００３０】
【数１２】

そして、磁界Ｈは数２より、下記数１３である。
【００３１】
【数１３】

これより、下記数１４となる。
【００３２】
【数１４】

数１２及び数１４より、表面からの深さ(ｚ)により磁界Ｈ及び電界Ｅは減衰することが分る。減衰の度合は、励磁周波数ｆ(上式では角周波数ω＝２πｆ)が高くなるほど浅い位置で減衰する。
【００３３】
本発明の磁気センサはこの周波数の違いによって、表面部、断面全体だけでなく、内部材質に応じた信号が得られるものである。図５はその原理を模式的に示している。
【００３４】
次に、Fe, Niといった強磁性体が使用された場合を説明する。強磁性体を考える上で、磁束密度Ｂに着目すると下記数１５となる。
【００３５】
【数１５】
Ｂ＝μＨ＋Ｍ
ここで、Ｍは磁化の強さであり、χ_ｍを磁化率とすると、Ｍ＝μ_０χ_ｍＨであるので、上記数１５は下記数１６となる。
【００３６】
【数１６】
Ｂ＝μ_０Ｈ＋Ｍ＝μ_０（１＋χ_ｍ）Ｈ＝μＨ
ただし、透磁率μ＝μ_０（１＋χ_ｍ）である。
【００３７】
また、相対透磁率κは、κ＝μ／μ_０＝１＋χ_ｍである。そして、
１)反磁性体の場合は、χ_ｍ＜０、μ＜μ_０
２)非磁性体の場合は、χ_ｍ＞０、μ＞μ_０
３)強磁性体の場合は、χ_ｍ＞１、μ＞μ_０
となる。
【００３８】
ただし、強磁性体でもクロム鋼のようなものは、χ_ｍ＞＞１、μ＞＞μ_０であり、ωが大であってもμの影響は大きく、磁束は増加する。全く磁性を持たない媒体(反磁性)の場合、μ＜μ_０であり(透磁率μより導電率σの影響が支配的となる)、磁化Ｍの影響がなく、磁界Ｈにより磁束密度が決まる。しかし、強磁性体の場合はμ＞μ_０であり、透磁率μの影響が強いものとなる。磁束密度は磁化Ｍに支配される(Ｂ＝＞＞μ_０Ｈ、よって、Ｂ≒Ｍ)。これにより、磁束の増加が起こり得ることになる。
【００３９】
一方センサ出力は下記数１７で表されるように、２次コイルに入る磁束によって決まることより、非磁性媒体を通過した磁束は減衰するのでセンサ出力は減少する。一方、強磁性媒体の場合は、磁束の増加が起こるのでセンサ出力が増加することが分る。
【００４０】
【数１７】

識別手段において、センタセンサ４０からの反射4KHｚ信号Ｒ４Ｓは材質の検出に利用されると共に、硬貨断面材質及び磁性／非磁性の判別情報として利用され、反射１６KHｚ信号Ｒ１６Ｓは硬貨中間断面材質の検出に利用されると共に、硬貨表面から中心近辺までの材質の判別情報として利用される。つまり、反射16KHｚ信号Ｒ１６Ｓはクラッド硬貨の検出に利用される。反射250KHｚ信号Ｒ２５０Ｓは硬貨の表面材質及び構成の検出に利用されると共に、硬貨表面層材質の判別として利用され、リング／コア境界部の波形に特徴が現れる情報となる。つまり、反射250KHｚ信号Ｒ２５０Ｓはバイカラー硬貨の検出に利用される。また、サイドセンサ２０にかかり透過L4KHz信号ＴＬ４Ｓと透過R4KHz信号ＴＲ４Ｓは材質×厚さの情報として利用され、透過L250KHz信号ＴＬ２５０Ｓと透過R250KHz信号ＴＲ２５０Ｓは硬貨形状の検出に利用され、材質×厚さ×径の情報として利用される。本例では、透過L16KHz信号及び透過R16KHz信号は硬貨の検出には利用していない。
【００４１】
本発明による上記識別の関係を表にまとめると、下記表１のようになる。
【００４２】
【表１】

図６に、反射信号の実際の検出信号を示す。特性曲線の上側より、反射4KHｚ信号、反射16KHｚ信号、反射250KHｚ信号を示している。
【００４３】
なお、本例では高周波数として２５０KHzを使用しているが、検出対象の非磁性材料の材質（AlとCuNi等）によって、信号出力の差異が小さい周波数帯で、磁性／非磁性材質による信号出力差異が小さい周波数帯であれば良く、数百KHz以上が好ましい。また、中周波数として１６KHZを使用しているが、検出対象の表面〜中心付近までの材質により信号出力差が現れる周波数帯であり、数十KHZオーダーの周波数帯である。低周波数として４KHzを使用しているが、検出対象全体の材質（導電率）により信号出力差が顕著に現れる周波数帯であれば良く、DC〜数KHzの周波数帯が好ましい。
【００４４】
本発明では、硬貨検出センサ１０上を通過する硬貨の中央部での各信号を特徴量とし、判別処理に用いる。トリガ方法は、通過センサ等が設置されている場合には、通過センサからの信号を基に大体の位置を検知し、硬貨中央部の検索を行う。また、通過センサを設けていない場合には、透過信号は材質（磁性／非磁性）に関係なく減衰し、高周波数ほど減衰量が大きく、片寄せ搬送ならば硬貨径に関係なく、片寄せ側コアに掛かる硬貨部は同じであることに基づき、透過L（片寄せ）の最小位置（減衰量最大位置）がほぼ硬貨中央部と考えられ、その位置での各信号値を各特徴量として良い。
【００４５】
次に、識別手段での識別動作を説明する。
【００４６】
先ず磁性／非磁性硬貨の判定であるが、磁性材料硬貨の信号特徴は、▲１▼反射低周波信号で磁束の増加があり、信号が増加する。▲２▼透過低周波信号では硬貨のエッジ部で磁束の収束を生じるので、波形に変曲が生じる。特徴として上記▲１▼の反射信号の増加が顕著に現れるため、この特徴を捉えることで磁性／非磁性硬貨の判定を行うことができる。図７（Ａ）はドイツ５Ｐｆ(Cu-Zn25 clad Fe)の反射4KHz信号Ｒ４Ｓであり、図７（Ｂ）はアメリカ１Ｃｔ(Cu-Zn5)の反射4KHz信号Ｒ４Ｓである。これから明らかなように、磁性材料である図７（Ａ）のドイツ５Ｐｆでは信号の増加（Ａ１部）であるのに対し、非磁性材料である図７（Ｂ）のアメリカ１Ｃｔでは信号の減少（Ａ２部）となり、信号の差異が分る。
【００４７】
次に、異なる金属板を積層したクラッド構造による信号の差異を説明すると、図８はAl均一硬貨サンプルの特性を示しており、Ｂ１，Ｂ２，Ｂ３はそれぞれAlのみの場合の４KHz,１６KHZ,２５０KHZの各反射信号を示している。図９はAl/CuZnNi/Alクラッド硬貨サンプルの特性を示しており、Ｂ４は表面層Al(厚み<0.5t)の特徴を表す反射250KHZ信号Ｒ２５０Ｓを示しており、Ｂ５は表面層Al(0.5t)+内層CuZnNi(<1.0t)の特徴を表す反射16KHZ信号Ｒ１６Ｓを示しており、Ｂ６はAl(1.0t)+CuZnNi(0.5t)＋ Al(1.0t)と全層の特徴を表す反射4KHZ信号Ｒ４Ｓを示している。また、図１０はCuZnNi均一硬貨サンプルの特性を示しており、Ｂ７，Ｂ８，Ｂ９はそれぞれCuZnNiのみの場合の４KHz,１６KHZ,２５０KHZの各反射信号を示している。更に、図１１はCuZnNi/Al/CuZnNiクラッド硬貨サンプルの特性を示しており、Ｂ１０はCuZnNi(<0.5t)の表面層の特徴を表す反射250KHZ信号Ｒ２５０Ｓを示しており、Ｂ１１はCuZnNi(0.5t)+ Al(<1.0t)と表面層及び内層の特徴を表す反射16KHZ信号Ｒ１６Ｓを示しており、Ｂ１２はCuZnNi(0.5t)+Al(1.0t)+CuZnNi(0.5t)と全層の特徴を表す反射4KHZ信号Ｒ４Ｓを示している。
【００４８】
図１２は、図８〜図１１と同一のサンプルに対する静止状態での反射信号の周波数特性を示しており、Al均一硬貨サンプル、CuZnNi均一硬貨サンプル、Al/CuZnNi/Alクラッド硬貨サンプル、CuZnNi/Al/CuZnNiクラッド硬貨サンプルに高周波、中周波、低周波で励磁したときのセンタセンサ４０を用いて出力を測定し減衰率をグラフにしたものである。高周波領域では、表皮効果の影響で磁束は表面層しか入れず減衰率も大きい。低周波領域では表皮効果の影響が少ないため、磁束は硬貨を突き抜け減衰率は小さい。中周波領域では低周波と高周波の両領域の中間の減衰率となる。これら特性より下記のことが言える。
【００４９】
表面部（表面から０．５ｍｍ以下）では表面部材質が同じであれば、反射250KHz信号Ｒ２５０Ｓも同一（Ｂ３＝Ｂ４、Ｂ９＝Ｂ１０）であり、約６０〜７０ＫＨｚ以上の周波数で、反射信号における表面部深さ０．５ｍｍ程度までの材質の影響が大きい。表面〜芯部（表面から１．５ｍｍ以下程度）では、表面部材質が同じでも、芯部材質により反射16KHz信号Ｒ１６Ｓは異なり（Ｂ２≠Ｂ５，Ｂ８≠Ｂ１１）、表面、芯部材質が同じでも、各厚みにより反射16KHz信号Ｒ１６Ｓは異なる（Ｂ５≠Ｂ１１）。また、約３０〜６０ＫＨｚの周波数で反射信号は表面部深さ０．５ｍｍ＋αの材質の影響を受け始め、約１０〜３０ＫＨｚではセンサ側表面部と芯部の材質の影響が大きい。
【００５０】
一方、断面全体では、表面部材質が同じでも両表面部、芯部を合わせた材質の厚さが異なれば、反射4KHz信号Ｒ４Ｓは異なり（Ｂ１≠Ｂ６，Ｂ７≠Ｂ１２）、表面部材質が異なっても両表面部、芯部を合わせた材質の厚さが同じであれば、反射4KHz信号Ｒ４Ｓも同じである（Ｂ６＝Ｂ１２）。約６〜８ＫＨｚ以下の周波数で対象断面を磁束が貫通し、全体の材質を合わせたものの影響をうけている信号が反射信号として得られる。
【００５１】
次に、リング部及びコア部が別材質で構成されるバイカラー硬貨の判定を説明する。
【００５２】
バイカラー硬貨では、例えば反射250KHz信号は図１３に示すように、硬貨のエッジ部の信号に変曲点が生じ、その傾きが反転するか（図１３（Ａ））、傾きがゼロになるか（図１３（Ｂ））、傾きが緩やかになる（図１３（Ｃ））。硬貨がバイカラー構造でない場合は、図１３（Ｄ）に示す様に変曲点が生じない。かかる特性を利用して、バイカラー硬貨の判定を行う。図１４はバイカラー硬貨に対する反射信号の周波数特性であり、低周波においては、センタセンサの磁束の広がりがコア部のみでなくリング部に及ぶため、Ｃ部に示すような差が生じる。リング部の導電率がコア部材の導電率より低い場合には、減衰率はコア部材のみでできた硬貨サンプルよりも減衰率は小さい。例えばリング部がAlでコア部材がCuZnNiの場合（●）は、CuZnNiの均一硬貨サンプル（×）より減衰率が大きくなる。これは、CuZnNiよりAlの方が導電率が高いためである。
【００５３】
コア部の４ＫＨｚ信号はリング部材質の影響を受けるため、バイカラー硬貨サンプルと均一材質硬貨サンプルでは、図１５の左に示すように差異を生じ、変曲点Ｄ１がバイカラー金属境界部の特徴である。図１５（Ａ）はリング部がAlで、コア部がCuZnNiのバイカラー硬貨サンプルであり、同図（Ｂ）はCuZnNiの均一硬貨サンプルである。また、図１６（Ａ）はリング部がCuZnNiで、コア部が空隙となっている穴明き硬貨サンプルの特性であり、同図（Ｂ）はCuZnNiの均一硬貨サンプルの特性である。
【００５４】
更に、図１７に示すように、バイカラー・クラッド構造のコア部４ＫＨｚ信号もリング部材質の影響を受ける。この結果、クラッド硬貨検知用の１６ＫＨｚ信号は、リング部の影響がないと考えられる。図１７（Ａ）はリング部がAlで、コア部がCuZnNi/Ni/CuZnNiのバイカラー・クラッド硬貨サンプルであり、同図（Ｂ）はリング部がCuZnNiで、コア部がCuZnNi/Ni/CuZnNiのバイカラー・クラッド硬貨サンプルである。
【００５５】
なお、検出信号を安定させるために、硬貨検出センサにプリアンプを内蔵するようにしても良い。上述では１つの発振器の出力を分周して低周波、中周波及び高周波の励磁信号を得ているが、各周波数の発振器を個別に設けても良い。また、上述では硬貨について説明したが、他の複数金属で構成された金属片に対しても適用可能である。
【００５６】
【発明の効果】
以上のように、本発明の金属片検出センサは従来の硬貨識別方式で用いられた硬貨全体と硬貨表面材質による特徴信号が得られる励磁周波数に加え、硬貨表面乃至中心近辺の材質による特徴信号の周波数を用いて検知しているので、クラッド硬貨の特徴である硬貨断面構造を推定することができる。バイカラー硬貨接合部での電気的な断続を表面電流の増減信号として捉えることで、バイカラー硬貨を判別できる。国内で流通している非磁性硬貨の場合、信号は減衰のみであるが、磁性硬貨の場合、信号は増加する。センサ信号処理において増加信号に対応することで、磁性貨、磁性を持つクラッド構造貨の材質判別が可能となる。
【図面の簡単な説明】
【図１】本発明で使用する硬貨検出センサの一例を示す一部断面斜視構造図である。
【図２】本発明で使用する硬貨検出センサの断面構造図である。
【図３】硬貨検出センサの励磁及び検出信号の処理系を示すブロック図である。
【図４】本発明の動作原理を説明するための図である。
【図５】本発明の動作原理を模式的に示す図である。
【図６】硬貨検出センサの検出信号の一例を示す特性図である。
【図７】硬貨の磁性／非磁性の特徴を示す特性図である。
【図８】 Al均一硬貨の特性を示す図である。
【図９】 Al/CuZnNi/Alクラッド硬貨の特性を示す図である。
【図１０】 CuZnNi均一硬貨の特性を示す図である。
【図１１】 CuZnNi/Al/CuZnNiクラッド硬貨の特性を示す図である。
【図１２】センタセンサ上でクラッド硬貨サンプルを静止させた状態での反射周波数特性例を示す図である。
【図１３】バイカラー硬貨の判定を説明するための図である。
【図１４】センタセンサ上でバイカラー硬貨を静止させた状態での反射信号周波数特性例を示す図である。
【図１５】バイカラー硬貨の判定に利用する特性例（左側バイカラー硬貨サンプル、右側均一硬貨サンプル）を示す図である。
【図１６】バイカラー硬貨の判定に利用する特性例（左側バイカラー硬貨サンプル、右側均一硬貨サンプル）を示す図である。
【図１７】バイカラー硬貨の判定に利用する特性例（左側バイカラー硬貨サンプル、右側均一硬貨サンプル）を示す図である。
【図１８】クラッド硬貨の構造を示す外観図である。
【図１９】バイカラー硬貨の構造を示す外観図である。
【符号の説明】
１ 発振器
２ 分周器
４ 加算器
５ 電流増幅器
１０ 硬貨検出センサ
１１ 通路
２０ サイドセンサ（透過型検出センサ）
２１ １次コイル
２２ サイドコア
２３ ２次コイル
３０ サイドセンサ（透過型検出センサ）
３１ １次コイル
３２ サイドコア
３３ ２次コイル
４０ センタセンサ（反射型検出センサ）
４１ ポットコア
４２ １次コイル
４３ ２次コイル[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a device for identifying a metal piece made of a plurality of materials, and particularly suitable for a coin processing machine such as a coin sorting machine, a coin depositing machine, a coin wrapping machine, etc., and a clad coin or a bicolor coin which is a metal piece made of a plurality of materials. The present invention relates to an apparatus for identifying a metal piece made of a plurality of highly reliable materials that can be reliably identified.
[0002]
[Prior art]
As a device for identifying a coin that is a metal piece, there is a coin identifying device as disclosed in Japanese Patent No. 2567654. This coin identification device excites the oscillation coil at high and low frequencies and takes the sum of the output attenuation of each frequency output from the receiving coil, so that the clad coin (bimetal coin) whose surface is the same material, and a single structure Coins are identified based on the fact that different outputs can be obtained with coins. Here, as shown in FIG. 18, the clad coin is a coin having a three-layer structure made of different materials such as aluminum (Al) or copper as a core material and white copper (CuNi) layered on both surfaces. The output of a normal white copper coin is distinguished from the output of a clad coin whose surface is white copper only by utilizing the fact that the output level of the signal is different.
[0003]
In addition, as shown in FIG. 19, the bicolor coin has a structure in which the metal of the core portion 100 in the central portion and the metal of the ring portion 101 in the peripheral portion are different, and there is a powerful means for identifying the bicolor coin. Not done.
[0004]
[Problems to be solved by the invention]
However, the conventional apparatus has a drawback that the clad coin cannot be reliably identified. This is because other types of single-material coins having the same output level as clad coins whose surface is white copper can exist.
[0005]
Conventionally, there has been no sensor or identification device capable of identifying coins having a composite material structure such as clad coins and bicolor coins.
[0006]
The present invention has been made under the circumstances described above, and an object of the present invention is to provide a highly reliable metal made of a plurality of materials capable of reliably identifying metal pieces such as clad coins and coins made of a plurality of materials. It is to provide a piece identification device.
[0007]
[Means for Solving the Problems]
The present invention relates to an apparatus for identifying a metal piece made of a plurality of materials, and the above object of the present invention is to provide a reflective detection system disposed on the sliding surface side of a passage for conveying coins that are metal pieces made of a plurality of metal materials. Sensor(40)A first transmission type detection sensor disposed so as to sandwich one end of the passage.(20)And a second transmission type detection sensor arranged to sandwich the other end of the passage(30)Metal piece detection sensor comprising(Ten)And the metal piece detection sensor(Ten)Identification means for identifying the coins based on the output of the output, and excitation signals of a plurality of frequencies are the reflection type detection sensor(40)Primary coil(42)The first transmission type detection sensor(20)Primary coil(twenty one)And the second transmission type detection sensor(30)Primary coil(31)The reflection type detection sensor(40)Secondary coil(43)Output of the first transmission type detection sensor(20)Secondary coil(twenty three)Output and the second transmission type detection sensor(30)Secondary coil(33)An identification device for a metal piece made of a plurality of materials, wherein the identification means identifies the coin passing through the passage based on the output of
  The first and second transmission type detection sensors (20,30) Core of (22,32) Are each formed in a U-shape and arranged opposite to each other in a bracket shape, and the reflection type detection sensor (40) The core of the cylindrical pot core (41) And the primary coil on the outer peripheral surface of the pot core. (42) The secondary coil is disposed on the inner peripheral surface of the pot core. (43) Are wound respectively, and the first and second transmission type detection sensors (20,30) Primary coil (21,31) Arranged so as to be sandwiched betweenThe excitation signal of the plurality of frequencies is a composite signal of low frequency, medium frequency and high frequency, and among the detection signals from the reflection type detection sensor, there is an inflection point in the detection signal waveform of the edge portion by the high frequency excitation signal. In some cases, this is accomplished by determining that the coin is a bicolor coin.
[0008]
furtherThe above object of the present invention isMetalMetal piece made of materialCarry coins that areaisleSliding surfaceReflective detection sensor arranged on the sideWhenOf the passageAt least someTransmissive detection sensor arranged to sandwichAnd fromA metal piece detection sensor comprising: the metal piece detection sensor based on the output of the metal piece detection sensor;coinIdentifying means for identifyingEquipped,
  MultipleofFrequency excitation signalButPrimary coil of the reflection type detection sensoras well asSupplied to the primary coil of the transmission type detection sensorIsThe output of the secondary coil of the reflection type detection sensoras well asBased on the output of the secondary coil of the transmission type detection sensor, the identification means passes through the passage.coinIdentifyA device for identifying a metal piece made of a plurality of materials,
  The excitation signals of the plurality of frequencies are a composite signal of low frequency, medium frequency and high frequency, and
  It is determined whether or not the coin is a clad coin by identifying a material near the center or the center of the coin by a detection signal based on a medium frequency excitation signal among detection signals from the reflection type detection sensor.Achieved by:
  Furthermore, the object of the present invention is to sandwich the transmission type detection sensor between the first transmission type detection sensor disposed so as to sandwich one end portion of the passage and the other end portion of the passage. This is achieved effectively by separately providing the second transmission type detection sensor.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, a metal piece sensor (primary coil) is excited at three frequencies, a high frequency, a medium frequency, and a low frequency, and the output signal is processed and discriminated, whereby a clad coin or a bicolor coin made of a plurality of materials is used. An identification device that reliably detects the metal piece is realized.
[0010]
Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, a coin and a coin sample having the same metal and structure as a metal piece as a metal piece will be described as an example, and a coin identification device will be described as an example of the identification device.
[0011]
FIG. 1 is a partially sectional perspective view showing the structure of a coin detection sensor 10 used in the present invention, and FIG. 2 is a sectional structural view thereof. The coin detection sensor 10 has a U-shaped shape having a clearance for attaching and detaching a conveyor belt (not shown) at the top, and a rectangular space bottom at the center forms a coin passage 11. On the outer surface, a shield plate 12 for shielding external magnetism is layered. The coin detection sensor 10 is provided with transmission detection type rectangular parallelepiped side sensors 20 and 30 so as to sandwich each end of the passage 11, and below the passage 11 is a reflection detection type cylindrical center. A sensor 40 is provided. The side sensors 20 and 30 are symmetric, and the side sensor 20 has a primary coil 21 and a secondary coil 23 wound on the top and bottom of an inverted U-shaped side core 22, and the side sensor 30 has a U-shape. A primary coil 31 and a secondary coil 33 are wound around the side core 32. The center sensor 40 has a cylindrical pot core 41, and a primary coil 42 is wound on the outer peripheral surface of the pot core 41, and a secondary coil 43 is wound and embedded on the inner peripheral surface. Furthermore, a coil (not shown) for the temperature sensor is provided.
[0012]
As a material for the passage 11, conductive ceramics (conductive alumina, conductive zirconia) are used as wear-resistant plates.
[0013]
In the present invention, excitation and detection signal processing are performed on the coin detection sensor 10 with the circuit configuration shown in FIG. That is, a square wave oscillation signal from the oscillator 1 is divided by the frequency divider 2 into a low frequency (4 KHz), a medium frequency (16 KHz), and a high frequency (250 KHz), and band pass filters (BPF) 3L and 3M for each frequency. , 3H, sine wave, synthesized (added) by the adder 4, and applied to the primary coils 21, 32 and 42 of the coin detection sensor 10 via the current amplifier 5. That is, the low-frequency, medium-frequency, and high-frequency combined excitation signals are supplied to the primary coils 21 and 31 of the side sensors 20 and 30 through the current amplifier 5 and to the primary coil 42 of the center sensor 40.
[0014]
The outputs of the secondary side coils 23, 33 and 43 are detected through amplifiers 44, 44L and 44R, respectively, and then reflected through a band pass filter, a full wave rectifier circuit and a low pass filter, respectively, and a reflected 4 kHz signal R4S, a reflected 16 kHz signal R16S, A reflected 250KHz signal R250S, a transmitted L4KHz signal TL4S, a transmitted L16KHz signal TL16S, a transmitted L250KHz signal TL250S, a transmitted R4KHz signal TR4S, a transmitted R16KHz signal TR16S, and a transmitted R250KHz signal TR250S are obtained. That is, the output of the secondary coil 43 of the center sensor 40 is frequency-separated into low frequency, medium frequency, and high frequency by the band-pass filters (BPF) 451 to 453 through the amplifier 44, and further, full-wave rectifier circuits 461 to 463 and Through a low-pass filter (LPF) 471 to 473, a reflected 4KHz signal R4S, a reflected 16KHz signal R16S, and a reflected 250KHz signal R250S are obtained. In the center sensor 40, the primary coil 42 and the secondary coil 43 form an eddy current loss type magnetic sensor.
[0015]
Further, the output of the secondary coil 23 of the side sensor 20 is frequency-separated into low frequency, medium frequency, and high frequency by the band pass filters (BPF) 45L1 to 45L3 through the amplifier 44L, respectively, and further, full wave rectifier circuits 46L1 to 46L3 and low pass. Through the filters (LPF) 47L1 to 47L3, a transmission L4KHz signal TL4S, a transmission L16KHz signal TL16S, and a transmission L250KHz signal TL250S are obtained. The output of the secondary coil 33 of the side sensor 30 is frequency-separated into a low frequency, a medium frequency, and a high frequency by bandpass filters (BPF) 45R1 to 45R3 through an amplifier 44R, and further, full wave rectifier circuits 46R1 to 46R3 and a low pass filter. Through (LPF) 47R1 to 47R3, a transmission R4KHz signal TR4S, a transmission R16KHz signal TR16S, and a transmission R250KHz signal TR250S are obtained. Further, the secondary coil output of the temperature sensor is output as the temperature monitor signal THS through the amplifier 481, the BPF 482, the full wave rectifier circuit 483, and the LPF 484.
[0016]
Reflected 4KHz signal R4S, Reflected 16KHz signal R16S, Reflected 250KHz signal R250S, Transmitted L4KHz signal TL4S, Transmitted L16KHz signal TL16S, Transmitted L250KHz signal TL250S, Transmitted R4KHz signal TR4S, Transmitted R16KHz signal TR16S, Transmitted R250KHz signal TR250S and Temperature monitor signal TH250S Then, it is input to an identification means (not shown) for identifying coins, and processing and determination are executed.
[0017]
The identifying means compares each feature amount with a determination frame provided in advance for each coin, and identifies the true / false of the coin. Although the signal difference due to the material is small at high frequencies, the attenuation rate is determined by the material of the surface layer, and at low frequencies it is also affected by the material of the intermediate layer, so the attenuation rate at each frequency is compared with a predetermined criterion. Thus, the coin can be identified. Further, in this example, the coins are moved to the side sensor 20 side and conveyed.
[0018]
Here, the operation principle of the present invention will be described as follows. Since both the reflection type detection sensor and the transmission type detection sensor change the magnetic flux depending on the medium entering between the coils, the transmission magnetic flux will be described here.
[0019]
In the relationship between the electric field and current shown in FIG. 4, x is the direction in which the current i flows, and from i = σE, the electric field E has only the x component. Here, the conductivity σ = 1 / ρ. The magnitude of the electric field E depends on the depth z from the surface and does not depend on the component y perpendicular to the component x. Next, according to Maxwell's equation, when the magnetic field is E (x component only), the magnetic flux density is B, the magnetic field is H (only y component), and the magnetic permeability is μ, the following equation 1 holds.
[0020]
[Expression 1]

When the magnetic flux density is D and the dielectric constant is ε, the following formula 2 is established.
[0021]
[Expression 2]

Then, the following formula 3 holds, and i = σE and D = εE, so the formula 3 becomes the formula 4.
[0022]
[Equation 3]

[Expression 4]

Therefore, the following formula 5 holds.
[0023]
[Equation 5]

When the magnetic field H is erased from the above formulas 1 and 5, and the formula of the electric field E is obtained, the following formula 6 is established.
[0024]
[Formula 6]

Next, when the electric field E is erased and the magnetic field H is expressed, the following equation 7 is established.
[0025]
[Expression 7]

Where E∝e^jωt(Where ω = 2πf), the following equation 8 and the expression of the damped vibration are obtained.
[0026]
[Equation 8]

For general non-magnetic metals, ε ≒ ε₀= 8.8542 × 10^-12Since F / m, σ = 1 / ρ≈1 / 10^-8-10^-7Εω / σ≈10^-18Degree. Also, ω²Since εμ can be ignored as compared with jωσμ unless ω becomes very large, it can be expressed by the following equation (9).
[0027]
[Equation 9]

From this, the following formula 10 is obtained, and δ represents the depth of the skin effect.
[0028]
[Expression 10]

In addition, the electric field E is attenuated to 1 / e at a depth of z = δ from the surface.
[0029]
## EQU11 ##

Here, when z = 0, E = E₀When A = E₀By the way, the above equation 11 becomes the following equation 12.
[0030]
[Expression 12]

And the magnetic field H is the following formula 13 from the formula 2.
[0031]
[Formula 13]

From this, the following Expression 14 is obtained.
[0032]
[Expression 14]

From Equations 12 and 14, it can be seen that the magnetic field H and the electric field E are attenuated by the depth (z) from the surface. The degree of attenuation is attenuated at a shallower position as the excitation frequency f (angular frequency ω = 2πf in the above equation) becomes higher.
[0033]
The magnetic sensor of the present invention can obtain a signal corresponding to the internal material as well as the entire surface and cross section due to the difference in frequency. FIG. 5 schematically shows the principle.
[0034]
Next, a case where a ferromagnetic material such as Fe or Ni is used will be described. Considering the magnetic flux density B in considering the ferromagnetic material, the following formula 15 is obtained.
[0035]
[Expression 15]
B = μH + M
Where M is the strength of magnetization and χ_mWhere M = μ₀χ_mSince it is H, the above formula 15 becomes the following formula 16.
[0036]
[Expression 16]
B = μ₀H + M = μ₀(1 + χ_m) H = μH
However, permeability μ = μ₀(1 + χ_m).
[0037]
The relative permeability κ is κ = μ / μ₀= 1 + χ_mIt is. And
1) For diamagnetic materials, χ_m<0, μ <μ₀
2) For non-magnetic materials, χ_m> 0, μ> μ₀
3) For ferromagnets, χ_m> 1, μ> μ₀
It becomes.
[0038]
However, even ferromagnets like chrome steel_m>> 1, μ >> μ₀Even if ω is large, the influence of μ is large, and the magnetic flux increases. In the case of a medium having no magnetism (diamagnetism), μ <μ₀(Effect of conductivity σ is more dominant than permeability μ), there is no influence of magnetization M, and magnetic flux density is determined by magnetic field H. However, in the case of a ferromagnetic material, μ> μ₀Therefore, the influence of the magnetic permeability μ is strong. The magnetic flux density is governed by the magnetization M (B = >> μ₀H, and therefore B≈M). As a result, an increase in magnetic flux can occur.
[0039]
On the other hand, since the sensor output is determined by the magnetic flux entering the secondary coil as expressed by the following equation 17, the magnetic flux that has passed through the nonmagnetic medium is attenuated, so that the sensor output decreases. On the other hand, in the case of a ferromagnetic medium, it can be seen that the sensor output increases because the magnetic flux increases.
[0040]
[Expression 17]

In the discriminating means, the reflected 4 kHz signal R4S from the center sensor 40 is used for detecting the material and also used as the coin cross-sectional material and magnetic / non-magnetic discrimination information, and the reflected 16 kHz signal R16S is used for detecting the coin intermediate cross-sectional material. In addition to being used, it is used as material discrimination information from the coin surface to the vicinity of the center. That is, the reflected 16 KHz signal R16S is used for detecting clad coins. The reflected 250 kHz signal R250S is used to detect the surface material and composition of the coin, and is also used to determine the surface layer material of the coin, and is information in which a characteristic appears in the waveform of the ring / core boundary. That is, the reflected 250 kHz signal R250S is used for detecting a bicolor coin. Further, the transmission L4KHz signal TL4S and the transmission R4KHz signal TR4S are used as material × thickness information, and the transmission L250KHz signal TL250S and the transmission R250KHz signal TR250S are used for coin shape detection, and the material × thickness ×. Used as diameter information. In this example, the transmitted L16 KHz signal and the transmitted R16 KHz signal are not used for coin detection.
[0041]
The identification relationships according to the present invention are summarized in a table as shown in Table 1 below.
[0042]
[Table 1]

FIG. 6 shows an actual detection signal of the reflected signal. From the upper side of the characteristic curve, a reflected 4 KHz signal, a reflected 16 KHz signal, and a reflected 250 KHz signal are shown.
[0043]
In this example, 250 KHz is used as the high frequency. However, depending on the material of the non-magnetic material to be detected (Al, CuNi, etc.), the signal output by the magnetic / non-magnetic material in the frequency band where the difference in signal output is small. A frequency band with a small difference may be used, and several hundred KHz or more is preferable. Further, although 16 KHZ is used as a medium frequency, this is a frequency band in which a signal output difference appears depending on the material from the surface to the center of the detection target, and is a frequency band on the order of several tens of KHZ. Although 4 KHz is used as the low frequency, it may be a frequency band in which a signal output difference is noticeable depending on the material (conductivity) of the entire detection target, and a frequency band of DC to several KHz is preferable.
[0044]
In the present invention, each signal at the center of the coin passing over the coin detection sensor 10 is used as a feature amount and used for the discrimination process. In the trigger method, when a passage sensor or the like is installed, a rough position is detected based on a signal from the passage sensor, and the central portion of the coin is searched. If no passing sensor is provided, the transmitted signal is attenuated regardless of the material (magnetic / nonmagnetic), and the amount of attenuation increases as the frequency increases. Based on the fact that the coin part applied to the core is the same, the minimum position (maximum attenuation position) of transmission L (shifting) is considered to be almost the coin central part, and each signal value at that position may be used as each feature value. .
[0045]
Next, the identification operation by the identification means will be described.
[0046]
First, the magnetic / non-magnetic coin is judged. The signal characteristic of the magnetic material coin is as follows. (1) The reflected low frequency signal has an increase in magnetic flux and the signal increases. {Circle around (2)} In the transmitted low-frequency signal, the magnetic flux converges at the edge of the coin, so that the waveform is inflected. As the feature, the increase in the reflected signal of the above (1) appears remarkably, and it is possible to determine the magnetic / nonmagnetic coin by capturing this feature. FIG. 7A shows a reflected 4 KHz signal R4S of German 5Pf (Cu-Zn25 clad Fe), and FIG. 7B shows a reflected 4 KHz signal R4S of America 1 Ct (Cu-Zn5). As is clear from this, the signal is increased (part A1) in the German 5Pf of FIG. 7A, which is a magnetic material, whereas the signal decrease (part A1) in FIG. 7B, which is a non-magnetic material, is the signal ( A2)) and the difference in signal is known.
[0047]
Next, the difference in signal due to the clad structure in which different metal plates are laminated will be explained. FIG. 8 shows the characteristics of an Al uniform coin sample, and B1, B2, and B3 are 4 KHz, 16 KHZ, and 250 KHZ when only Al is used. Each reflected signal is shown. FIG. 9 shows the characteristics of the Al / CuZnNi / Al clad coin sample, B4 shows the reflected 250KHZ signal R250S representing the characteristics of the surface layer Al (thickness <0.5 t), and B5 shows the surface layer Al (0.5 t). ) + Reflected 16KHZ signal R16S representing the characteristics of the inner layer CuZnNi (<1.0t), B6 is Al (1.0t) + CuZnNi (0.5t)+ Al (1.0t)And a reflected 4KHZ signal R4S representing the characteristics of all layers. FIG. 10 shows the characteristics of a CuZnNi uniform coin sample, and B7, B8, and B9 show 4KHz, 16KHZ, and 250KHZ reflected signals when only CuZnNi is used. Further, FIG. 11 shows the characteristics of a CuZnNi / Al / CuZnNi clad coin sample, B10 shows a reflected 250 KHZ signal R250S representing the characteristics of the surface layer of CuZnNi (<0.5 t), and B11 shows CuZnNi (0.5 t). ) + Al (<1.0t) and the reflected 16KHZ signal R16S representing the characteristics of the surface layer and inner layer, B12 is the characteristic of CuZnNi (0.5t) + Al (1.0t) + CuZnNi (0.5t) and all layers Shows a reflected 4KHZ signal R4S.
[0048]
FIG. 12 shows the frequency characteristics of the reflected signal in a stationary state with respect to the same samples as in FIGS. 8 to 11, and Al uniform coin sample, CuZnNi uniform coin sample, Al / CuZnNi / Al clad coin sample, CuZnNi / Al. This is a graph showing the attenuation rate by measuring the output using the center sensor 40 when the / CuZnNi clad coin sample is excited at high frequency, medium frequency, and low frequency. In the high frequency region, the magnetic flux enters only the surface layer due to the skin effect, and the attenuation factor is large. Since the skin effect is less affected in the low frequency region, the magnetic flux penetrates the coin and the attenuation rate is small. In the middle frequency region, the attenuation factor is intermediate between both the low frequency and high frequency regions. The following can be said from these characteristics.
[0049]
If the surface member quality is the same at the surface portion (0.5 mm or less from the surface), the reflected 250 KHz signal R250S is the same (B3 = B4, B9 = B10), and the reflected signal has a frequency of about 60 to 70 KHz or higher. The influence of the material up to the surface depth of about 0.5 mm is great. From the surface to the core (about 1.5 mm or less from the surface), even if the surface member quality is the same, the reflected 16 KHz signal R16S differs depending on the core member quality (B2 ≠ B5, B8 ≠ B11), and the surface and core member quality are the same. The reflected 16 KHz signal R16S differs depending on the thickness (B5 ≠ B11). Further, the reflected signal starts to be influenced by the material having a surface depth of 0.5 mm + α at a frequency of about 30 to 60 KHz, and at about 10 to 30 KHz, the influence of the material on the sensor side surface and the core is large.
[0050]
On the other hand, in the whole cross section, if the surface material quality is the same, but the thickness of the material including both the surface portion and the core portion is different, the reflected 4 kHz signal R4S is different (B1 ≠ B6, B7 ≠ B12), and the surface member quality is different. However, if the thickness of the material of both the surface portion and the core portion is the same, the reflected 4 KHz signal R4S is also the same (B6= B12). A magnetic flux penetrates the target cross section at a frequency of about 6 to 8 KHz or less, and a signal that is influenced by the total material is obtained as a reflected signal.
[0051]
Next, determination of bicolor coins in which the ring part and the core part are made of different materials will be described.
[0052]
In a bicolor coin, for example, as shown in FIG. 13, the reflected 250 KHz signal has an inflection point in the signal at the edge of the coin, and the inclination is reversed (FIG. 13A), or the inclination is zero. (FIG. 13B), the inclination becomes gentle (FIG. 13C). When the coin does not have a bicolor structure, an inflection point does not occur as shown in FIG. By using such characteristics, bicolor coins are determined. FIG. 14 shows the frequency characteristics of the reflected signal with respect to the bicolor coin. At low frequencies, the spread of the magnetic flux of the center sensor extends not only to the core part but also to the ring part. When the conductivity of the ring portion is lower than the conductivity of the core member, the attenuation rate is smaller than that of a coin sample made of only the core member. For example, when the ring part is Al and the core member is CuZnNi (●), the attenuation rate is larger than that of the CuZnNi uniform coin sample (×). This is because Al has higher conductivity than CuZnNi.
[0053]
Since the 4KHz signal at the core is affected by the ring member quality, a difference occurs between the bicolor coin sample and the uniform material coin sample as shown on the left of FIG. 15, and the inflection point D1 is a feature of the bicolor metal boundary. It is. FIG. 15A is a bicolor coin sample in which the ring portion is Al and the core portion is CuZnNi, and FIG. 15B is a uniform coin sample of CuZnNi. FIG. 16 (A) shows the characteristics of a perforated coin sample in which the ring part is CuZnNi and the core part is a void, and FIG. 16 (B) shows the characteristics of a uniform coin sample of CuZnNi.
[0054]
Further, as shown in FIG. 17, the core 4KHz signal of the bicolor clad structure is also affected by the ring member quality. As a result, the 16 KHz signal for clad coin detection is considered not to be affected by the ring portion. 17A is a bicolor clad coin sample in which the ring part is Al and the core part is CuZnNi / Ni / CuZnNi, and FIG. 17B is the ring part is CuZnNi and the core part is CuZnNi / Ni / CuZnNi. This is a bicolor clad coin sample.
[0055]
In order to stabilize the detection signal, a preamplifier may be incorporated in the coin detection sensor. In the above description, the output of one oscillator is frequency-divided to obtain low-frequency, medium-frequency and high-frequency excitation signals, but oscillators of each frequency may be provided individually. Moreover, although the coin was demonstrated above, it is applicable also to the metal piece comprised with the other multiple metal.
[0056]
【The invention's effect】
As described above, the metal piece detection sensor of the present invention has a feature signal based on the material on the surface of the coin or in the vicinity of the center, in addition to the excitation frequency at which the feature signal based on the entire coin and the coin surface material used in the conventional coin identification system is obtained. Since the detection is performed using the frequency, the cross-sectional structure of the coin, which is a characteristic of the clad coin, can be estimated. Bi-color coins can be identified by capturing the electrical interruption at the bi-color coin joint as an increase / decrease signal of the surface current. In the case of non-magnetic coins distributed in the country, the signal is only attenuated, but in the case of magnetic coins, the signal increases. By responding to the increase signal in the sensor signal processing, it is possible to determine the material of the magnetic coin and the clad structure coin having magnetism.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional perspective view showing an example of a coin detection sensor used in the present invention.
FIG. 2 is a sectional structural view of a coin detection sensor used in the present invention.
FIG. 3 is a block diagram showing a processing system for excitation and detection signals of a coin detection sensor.
FIG. 4 is a diagram for explaining an operation principle of the present invention.
FIG. 5 is a diagram schematically showing the operation principle of the present invention.
FIG. 6 is a characteristic diagram showing an example of a detection signal of a coin detection sensor.
FIG. 7 is a characteristic diagram showing magnetic / nonmagnetic characteristics of coins.
FIG. 8 is a diagram showing characteristics of Al uniform coins.
FIG. 9 is a diagram showing characteristics of Al / CuZnNi / Al clad coins.
FIG. 10 is a diagram showing the characteristics of CuZnNi uniform coins.
FIG. 11 is a view showing characteristics of CuZnNi / Al / CuZnNi clad coins.
FIG. 12 is a diagram illustrating an example of a reflection frequency characteristic in a state where a clad coin sample is stationary on a center sensor.
FIG. 13 is a diagram for explaining determination of bicolor coins.
FIG. 14 is a diagram illustrating an example of a reflected signal frequency characteristic in a state where a bicolor coin is stationary on a center sensor.
FIG. 15 is a diagram showing characteristic examples (left bicolor coin sample, right uniform coin sample) used for determination of bicolor coins.
FIG. 16 is a diagram showing characteristic examples (left bicolor coin sample, right uniform coin sample) used for determination of bicolor coins.
FIG. 17 is a diagram showing characteristic examples (left bicolor coin sample, right uniform coin sample) used for determination of bicolor coins.
FIG. 18 is an external view showing the structure of a clad coin.
FIG. 19 is an external view showing the structure of a bicolor coin.
[Explanation of symbols]
1 Oscillator
2 frequency divider
4 Adder
5 Current amplifier
10 Coin detection sensor
11 passage
20 Side sensor (Transmission type detection sensor)
21 Primary coil
22 Side core
23 Secondary coil
30 Side sensor (Transmission type detection sensor)
31 Primary coil
32 side core
33 Secondary coil
40 Center sensor (reflection type detection sensor)
41 Pot Core
42 Primary coil
43 Secondary coil

Claims (1)

A reflection type detection sensor (40) disposed on a sliding surface side of a passage for conveying coins which are metal pieces made of a plurality of metal materials, a first detection portion disposed so as to sandwich one end portion of the passage. A metal piece detection sensor (10) comprising a transmission type detection sensor (20) and a second transmission type detection sensor (30) disposed so as to sandwich the other end of the passage;
An identification means for identifying the coin based on the output of the metal piece detection sensor (10) ,
Excitation signals having a plurality of frequencies are supplied to the primary side coil (42) of the reflection type detection sensor (40) , the primary side coil (21) of the first transmission type detection sensor (20) , and the second transmission type. Supplied to the primary coil (31) of the detection sensor (30) , the output of the secondary coil (43) of the reflection type detection sensor (40) , the secondary of the first transmission type detection sensor (20) A plurality of materials in which the identification means identifies the coin passing through the passage based on the output of the side coil (23) and the output of the secondary coil (33) of the second transmission type detection sensor (30). A metal piece identification device comprising:
The cores (22, 32) of the first and second transmission type detection sensors (20, 30) are each formed in a U-shape and are arranged opposite to each other in a bracket shape,
The core of the reflection type detection sensor (40) is a cylindrical pot core (41) , the primary coil (42) is provided on the outer peripheral surface of the pot core , and the secondary coil is provided on the inner peripheral surface of the pot core. (43) are wound around each other and arranged so as to be sandwiched between the primary side coils (21, 31) of the first and second transmission type detection sensors (20, 30). ,further,
The excitation signals of the plurality of frequencies are a composite signal of low frequency, medium frequency and high frequency, and
Among the detection signals from the reflection type detection sensor, when there is an inflection point in the detection signal waveform of the edge portion by the high frequency excitation signal, the coin is determined to be a bicolor coin. A metal piece identification device comprising.

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