JP4658342B2

JP4658342B2 - Water quality checker circuit

Info

Publication number: JP4658342B2
Application number: JP2001014866A
Authority: JP
Inventors: 一夫翁長; 順子柳谷
Original assignee: FIS Inc
Current assignee: FIS Inc
Priority date: 2001-01-23
Filing date: 2001-01-23
Publication date: 2011-03-23
Anticipated expiration: 2021-01-23
Also published as: JP2002214220A

Description

【０００１】
【発明の属する技術分野】
本発明は水道水の塩素濃度や、アルカリ生成水のアルカリ度合の何れのチェックにも使える水質チェッカ回路に関するものである。
【０００２】
【従来の技術】
従来液中の塩素濃度或いはアルカリ度合を一対の電極の起電圧によってチェックするものがあるが、塩素濃度を測定する場合と、アルカリ度合の測定時とで電極間の起電圧の方向が逆であるため、塩素濃度が略零、つまりきれいな水と、アルカリ度合が所定以上ある液とが共に”良”と評価するような場合において、同一の発光ダイオードを用いて”良”であることを評価表示しようとすると、起電圧の方向が逆であるため検知信号処理のための回路構成が複雑になるという問題があった。
【０００３】
【発明が解決しようとする課題】
本発明は、上述の問題点に鑑みて為されたもので、その目的とするところは、アルカリ度合も塩素濃度もチェックすることができ、しかも表示手段により、水質の評価表示する場合に、塩素濃度、アルカリ度合の何れの測定時にも同じ表示手段によって評価表示することができる水質チェッカ回路を提供することにある。
【０００４】
【課題を解決するための手段】
上記の目的を達成するために、請求項１の発明では、電源と、異種の金属により構成され、検知対象の液中に浸けられたときに電圧を発生して検知信号として出力する一対の電極と、塩素濃度の検知対象の液中に浸けたときに起電圧のマイナス側となり、アルカリ度合の検知対象の液中に浸けたときに起電圧のプラス側となる一方の電極を接続する接続ラインの電位を上記電源のマイナスグランドから見て一定の電位に保持する手段と、上記検知信号を非反転入力端に入力し、出力端と反転入力端に接続した抵抗と反転入力端と基準電位との間に接続した抵抗とで定まる利得で検知信号を非反転増幅する信号増幅用の第１演算増幅器と、上記電源のプラス極と上記接続ラインとの間に接続された複数の抵抗の直列回路によって構成される分圧回路から出力される複数の異なる分圧出力に対応して設けられて、異なる分圧出力により基準電圧が夫々設定され、該基準電圧と上記第１演算増幅器から出力される検知信号電圧とを比較する複数のコンパレータと、該各コンパレータに対応して設けられて各コンパレータの出力端と上記電源との間に接続され、上記対応するコンパレータの出力に応じて駆動され、検知結果を表示する表示手段とを備えるとともに、塩素濃度測定時には上記基準電位を上記接続ラインの電位とし、アルカリ度合測定時には上記基準電位を上記接続ラインの電位よりもマイナス方向に低く切換設定する手段を備えて、測定するアルカリ度合が所定以上高い場合から所定以下に至るまでの上記第１演算増幅器から出力される検知信号電圧の変化と、測定する塩素濃度が略零の場合から所定濃度以上に至るまでの上記第１演算増幅器から出力される検知信号電圧の変化が略同じとなるように上記第１演算増幅器の利得を設定したことを特徴とする。
【０００５】
請求項２の発明では、請求項１の発明において、上記接続ラインの電位を一定に保持する手段を、上記電源の電圧を所定電圧に降圧した電圧を非反転入力端に入力して略同じ電圧を出力に発生するように利得が設定された非反転増幅器を構成する第２演算増幅器により構成し、該第２演算増幅器の出力端に上記接続ラインを接続して成ることを特徴とする。
【０００６】
請求項３の発明では、請求項１又は２の発明において、上記切換手段として、反転入力端と出力端が接続された第３演算増幅器と、該第３演算増幅器の非反転入力端に入力する電圧を上記接続ラインの電圧とこの接続ラインよりも低い電圧とに切り換える電圧切換手段とから構成し、上記第３演算増幅器の出力端の電位を上記基準電位としたことを特徴とする。
【０００７】
請求項４の発明では、請求項１乃至３の何れかの発明において、上記各コンパレータの非反転入力端に上記信号増幅用の第１演算増幅器からの検知信号電圧を、上記各コンパレータの反転入力端に基準電圧を夫々入力し、基準電圧より入力する検知信号電圧が低いコンパレータをオンして上記表示手段を動作させることを特徴とする。
【０００８】
請求項５の発明では、請求項１乃至４の何れかの発明において、上記電源が電池電源を安定化する定電圧回路の出力により構成して成ることを特徴とする。
【０００９】
【発明の実施の形態】
以下本発明を一実施形態により説明する。
【００１０】
図１は本実施形態の回路を示しており、図において、乾電池、二次電池等の電池電源１に対して塩素濃度測定開始用スイッチＳＷ１とアルカリ度合の測定開始用スイッチＳＷ２との並列回路を介して汎用ＩＣ等からなる定電圧回路２を接続し、この定電圧回路２により安定化した電源電圧を得、この電圧を抵抗Ｒ１，Ｒ２の抵抗分圧回路により分圧して非反転増幅器を構成する演算増幅器ＯＰ１（第２演算増幅器）の非反転入力端に印加し、この演算増幅器ＯＰ１の出力端と反転入力端との間に接続した抵抗Ｒ３、Ｒ４の直列回路の中点電位を、水質評価を段階的に表示するための表示回路４のコンパレータＣＰ１〜ＣＰ５の基準電圧のグランドレベルとするとともに、センサ用電極３ａ、３ｂ間に発生する起電力による検出信号電圧のグランドレベルとしている。
【００１１】
電極３ａ、３ｂ間には抵抗Ｒ５，Ｒ６の直列回路を接続し、該直列回路の中点を検出信号増幅用の演算増幅器ＯＰ２（第１演算増幅器）の非反転入力端に接続してある。この非反転入力端はコンデンサＣ１を介して上記定電圧回路２の出力端のプラス極側にも接続してある。
【００１２】
演算増幅器ＯＰ２は非反転増幅器を構成し、出力端と反転入力端との間には可変抵抗器ＶＲ１、応答調整用のコンデンサＣ２からなる並列回路を接続してあり、この可変抵抗器ＶＲ１の抵抗値と、反転入力端とグランド（基準）となる後述する演算増幅器ＯＰ３の出力端との間に接続した抵抗Ｒ７とで利得が設定され、該利得は可変抵抗器ＶＲ１で調整することができるようになっている。
【００１３】
また一方上記抵抗Ｒ３，Ｒ４の直列回路の中点と、電池電源１のマイナス極との間には抵抗Ｒ８を介して可変抵抗器ＶＲ２とスイッチＳＷ２１の直列回路を接続するとともに、可変抵抗器ＶＲ２，スイッチＳＷ２１の直列回路にノイズ除去用コンデンサＣ３を接続し、抵抗Ｒ８と可変抵抗器ＶＲ２の接続点に演算増幅器ＯＰ３の非反転入力端を接続してある。
【００１４】
この演算増幅器ＯＰ３（第３演算増幅器）は、ボルテージフォロアの非反転増幅器を構成し、非反転入力端の入力電圧と、出力電圧とが等しく、その出力端を抵抗Ｒ７を介して上記演算増幅器ＯＰ２の反転入力端に接続し、演算増幅器ＯＰ２のグランドの電位（基準電位）を出力端の電位に設定するようになっている。
【００１５】
上記スイッチＳＷ２１はアルカリ度合測定開始用スイッチＳＷ２のオン／オフに連動してオン／オフするスイッチであって、演算増幅器ＯＰ２の入力電圧の切換手段を構成する。
【００１６】
表示回路４は５つのコンパレータＣＰ１〜ＣＰ５、このコンパレータＣＰ１〜ＣＰ５の出力端と定電圧回路２の出力端のプラス極との間に限流抵抗Ｒ１１〜Ｒ１５を介して接続された表示手段を構成する発光ダイオードＬ１〜Ｌ５等から構成されている。そして上記定電圧回路２の出力端のプラス極と、上記抵抗Ｒ３，Ｒ４の直列回路の中点との間に同一抵抗値の抵抗Ｒ１６〜Ｒ２１の直列回路からなる分圧回路を接続し、抵抗Ｒ２１と抵抗Ｒ２０との接続点の分圧電圧をコンパレータＣＰ１の反転入力端に基準電圧として接続し、また抵抗Ｒ２０と抵抗Ｒ１９との接続点の分圧電圧をコンパレータＣＰ２の反転入力端に基準電圧として接続し、更に抵抗Ｒ１９と抵抗Ｒ１８との接続点の分圧電圧をコンパレータＣＰ３の反転入力端に基準電圧として接続し、同様に抵抗Ｒ１８と抵抗Ｒ１７との接続点の分圧電圧をコンパレータＣＰ４の反転入力端に基準電圧として接続し、更に抵抗Ｒ１７と抵抗Ｒ１６との接続点の分圧電圧をコンパレータＣＰ５の反転入力端に基準電圧として接続しており、コンパレータＣＰ１の基準電圧からコンパレータＣＰ５の基準電圧までを順次段階的に高めてある。
【００１７】
一方コンパレータＣＰ１〜ＣＰ５の非反転入力端には、夫々抵抗Ｒ２２〜Ｒ２６を介して上記演算増幅器ＯＰ２の出力端を接続してあり、これら抵抗Ｒ２２〜Ｒ２６は同じ抵抗値のものが使用されている。
【００１８】
図２は本発明水質チェッカ回路を用いた水質チェッカの外観を示すものであって、樹脂成形品からなるハウジング５は図１で示す回路及び電池電源１を内装するとともに、外面にスイッチＳＷ１及びＳＷ２の操作部や表示回路４の発光ダイオードＬ１〜Ｌ５の発光部が露設された本体部６と、本体部６の前部から前方に突出するように形成された、先端部に一対の電極３ａ，３ｂからなるセンサ部が設けられているヘッド部７とから構成されている。
【００１９】
このハウジング５は外因性内分泌撹乱化学物質（環境ホルモン）を含まない材質にて形成することが好ましく、例えばＡＢＳ樹脂等のような樹脂成形品にて形成される。
【００２０】
またヘッド部７は前後方向に長い円筒状に形成されており、その内部の中空部は後端側にて本体部６内に連通し、前端側が前方に向けて開口している。ここで、ヘッド部７の前端部には、図４に示すように、開口の周縁の全周に亘って、前方に突出すると共にヘッド部７の外径寸法よりも小さい外径寸法を有する円筒状の嵌合リブ８が設けられており、この嵌合リブ８の外周面には全周に亘って嵌合凹部９が凹設されると共に、嵌合凹部９よりも前端側は嵌合凹部９よりも外周側に突出した嵌合凸部１０として形成されている。
【００２１】
ヘッド部７の先端部には、ヘッド部７の内外の水密性を確保すると共に端子電極３ａ，３ｂを固定するための固定部材１１が装着されている。固定部材１１は環境ホルモンを含まない材質にて形成することが好ましく、例えばＡＢＳ樹脂等のような樹脂成形品にて形成されるものであり、円柱状に形成された係止部１２の前端側に係止部１２よりも小径の円筒状の突出部１３を形成し、係止部１２の後端側に係止部１２よりも小径の円筒状の挿入部１４を形成したものである。
【００２２】
このとき突出部１３には前方に開口する前側凹部１５が形成され、挿入部１４には後方に開口する後側凹部２２が形成されているものであり、この前側凹部１５と後側凹部２２とは係止部１２によって仕切られている。
【００２３】
またこの係止部１２には、前側凹部１５と後側凹部２２とを連通する二つの挿通孔１６が形成されている。また、固定部材１１の挿入部１４の外周面には、全周に亘る凹溝１７が形成されている。
【００２４】
この固定部材１１は、図２に示すように挿入部１４をハウジング５のヘッド部７の前端開口から挿入することによりヘッド部７の前端に取り付けられるものであり、このとき挿入部１４にＯリング１８を取着することにより挿入部１４の外面とヘッド部７の内面との間の水密性を確保することができる。
【００２５】
また更に挿入部１４の外面とヘッド部７の内面との間の隙間に接着剤を充填してヘッド部７と固定部材１１とを接着することにより、固定部材１１をヘッド部７に対して強固に固定すると共に挿入部１４の外面とヘッド部７の内面との間の水密性を更に向上することができる。
【００２６】
ヘッド部７の中空部内には二本のリード線１９ａ，１９ｂが配設されており、各リード線１９ａ，１９ｂの後端部はハウジング５の本体部６に引き出されて制御部に接続され、前端部は固定部材１１に固定されている。また二本のリード線１９ａ，１９ｂの先端にはそれぞれ電極３ａ，３ｂが接続されている。
【００２７】
ここで、リード線１９ａ，１９ｂは固定部材１１の係止部１２の挿通孔１６に挿通されて後端側が挿入部１４の後側凹部２２内から後端開口を介して固定部材１１の後方に引き出されている。またリード線１９ａ，１９ｂの先端の末端部には挿通孔１６の内径よりも大きい球状の瘤部２０が形成されており、この瘤部２０によってリード線１９ａ，１９ｂの先端は突出部１３の前側凹部１５内において係止部１２の前面側に係止されている。このリード線１９ａ，１９ｂの先端の瘤部２０にはそれぞれ線状の電極３ａ，３ｂの後端が埋設されており、これによりリード線１９ａ，１９ｂの先端には電極３ａ，３ｂが接続されている。各電極３ａ，３ｂは先端側は固定部材１１の突出部１３の前側凹部１５の開口から前方に突出するように配設されている。
【００２８】
また固定部材１１の挿入部１４の後側凹部２２内には封止材２１が充填されており、これにより固定部材１１の挿入部１４の後側凹部２２内においてリード線１９ａ，１９ｂが固定されている。また固定部材１１の突出部１３の前側凹部１５内にも封止材２３が充填されており、これによりこれ固定部材１１の突出部１３の前側凹部１５内において電極３ａ，３ｂが固定されている。また、これらの封止材２３，１９によって、固定部材１１の前端側と後端側との間の水密性が確保される。
【００２９】
一対の電極３ａ，３ｂは、一方の電極３ｂが白金線、他方の電極３ａが銀線にて形成されており、この電極３ａ，３ｂによって、センサ部が構成されている。各電極３ａ，３ｂは後端側は固定部材１１の突出部１３の前側凹部１５内において封止材２３内に埋設されている埋設部として形成され、前端側はこの封止材２３から前方に向けて突出する検知部位として形成されている。
【００３０】
銀線からなる電極３ａには検知端子部７の表面のみに塩化銀被膜が形成され、埋設部の表面には塩化銀被膜は形成されていないものであり、このため、電極３ａとリード線１９ａとの接続部には塩化銀被膜は形成されることがなく、電極３ａとリード線１９ａとの電気的接続が塩化銀被膜によって阻害されることがないものである。
【００３１】
更に、ヘッド部７の先端には、固定部材１１及び電極３ａ，３ｂの検知端子部７を覆うようにキャップ体２４が設けられ、これにより検知端子部７の保護が行なわれる。このキャップ体２４は図３に示すように、前端側が閉塞すると共に後端側が開口した有底円筒状に形成されており、その外径寸法はヘッド部７の外径寸法と略同一に形成される。またキャップ体２４の後端部は、内径寸法が前端側よりも大きくかつ固定部材１１の係止部１２の外径と略同一の寸法に形成された、被嵌合リブ２５として形成されており、この被嵌合リブ２５の後端部の内周面には全周に亘って、ヘッド部７の嵌合リブ８の嵌合凸部１０に合致する被嵌合凹部２６が形成されると共に、この被嵌合凹部２６よりも更に後端側は被嵌合凹部２６よりも内周側に突出した、嵌合リブ８の嵌合凹部９に合致する被嵌合凸部２７として形成されている。そしてキャップ体２４の被嵌合リブ２５を固定部材１１の係止部１２の外周側からヘッド部７の嵌合リブ８の外周側にかけて配置し、嵌合凹部９と被嵌合凸部２７とを嵌合させると共に嵌合凸部１０と被嵌合凹部２６とを嵌合させることにより、キャップ体２４がヘッド部７の前端に取り付けられるものであり、このとき嵌合リブ８と被嵌合リブ２５との間の隙間に接着剤を充填してキャップ体２４とヘッド部７とを接着することにより、キャップ体２４をヘッド部７に対して強固に固定すると共に嵌合リブ８と被嵌合リブ２５との間の水密性を確保することができるものである。
【００３２】
このキャップ体２４には、二つの平行並列なスリット状の開口部２８が形成されており、この開口部２８により、キャップ体２４の内側と外側とが連通されている。この開口部２８はキャップ体２４の側面から前端面を通って反対側の側面に亘るように形成されている。またキャップ体２４には各開口部２８の両端部に、この開口部２８と連通すると共にキャップ体２４の内側と外側とを連通する連通孔２９が形成されており、この連通孔２９は各開口部２８の幅よりも大径に形成されている。
【００３３】
このキャップ体２４のスリット状の開口部２８は、水質の測定時にキャップ体２４の内側に水道水等の検出対象の液体を侵入させて電極２の検知端子部７をこの液体に浸漬させたり、水質の測定後にキャップ体２４の内側から液体を排出したりするためのものである。
【００３４】
また連通孔６は水質の測定時にキャップ体２４の内側から空気を排出してキャップ体２４の内側に検出対象の液体がスムーズに侵入するようにし、あるいは水質の測定後にキャップ体２４の内側に空気を侵入させてキャップ体２４の内側から液体がスムーズに排出されるようにするためのものである。
【００３５】
次に本実施形態の水質チェッカ回路の動作について説明する。
【００３６】
まず水道水の塩素濃度をチェックする場合には、スイッチＳＷ１をオンして、ヘッド部７を被検知対象液である水道水に浸ける。水道水に漬けられたキャップ体２４内の電極３ａ、３ｂ間には塩素濃度に応じて起電圧が発生する。この場合電極３ａがプラス極となって、起電圧によって抵抗Ｒ６には電圧が発生し、この電圧が検出信号でとして演算増幅器ＯＰ２に非反転入力端に入力され、非反転増幅される。
【００３７】
一方定電圧回路２からの出力電圧が抵抗Ｒ１と、抵抗Ｒ２とで分圧されて降圧され、抵抗Ｒ２の両端電圧が演算増幅器ＯＰ１により非反転増幅される。ここで演算増幅器ＯＰ１の出力端と反転入両端に接続された抵抗Ｒ４、Ｒ３の抵抗値を、その中点に接続されている接続ラインＡの電圧が略抵抗Ｒ２の両端電圧に略等し入力電圧となるように設定してある。
【００３８】
またスイッチＳＷ２１がオフ状態であるため演算増幅器ＯＰ３では出力端の電圧が非反転入力端に入力している電圧、つまり接続ラインＡの電圧と等しい電圧となる。従ってこの出力端の電位と、接続ラインＡの電位とが等しいため、演算増幅器ＯＰ２は可変抵抗器ＶＲ１の抵抗値と、反転入力端と演算増幅器ＯＰ３の出力端との間に接続した抵抗Ｒ７の抵抗値とで定まる利得により、抵抗Ｒ６の両端に発生する検出信号電圧を増幅する。
【００３９】
この演算増幅器ＯＰ３により増幅された検出信号電圧は、表示回路４に入力されて、各コンパレータＣＰ１〜ＣＰ５に設定される基準電圧と比較される。そして検出信号電圧が基準電圧を越えていないコンパレータにおいては、出力端を”Ｌ”レベルとし、出力端に接続されている発光ダイオードに発光電流を流す。つまり被測定水の塩素濃度が高ければ高い程、電極３ａ、３ｂ間に発生する起電圧が増加して、抵抗Ｒ６の両端電圧が高くなり、そのため基準電圧を越えるコンパレータの数が多くなり、発光する発光ダイオードの数が少なくなる。従って発光ダイオードＬ１〜Ｌ５の全てが点灯している場合には塩素濃度が略零に近くて水質評価は”良”となり、その点灯数が少なくなればなるほど塩素濃度が高く、水質評価は”悪”であることが分かる。またヘッド部７を水道水に浸ける前に、スイッチＳＷ１を投入した時点からコンデンサＣ１が充電されその充電に伴ってゆっくりと発光ダイオードＬ１〜５が順次点灯し、この点灯により動作チェックができることになるようになっている。この動作は塩素濃度測定時のみで、後述するアルカリ度合の測定時ではこの点灯動作は無い。
【００４０】
さて本発明チェッカ回路は水道水の塩素濃度以外に、アルカリ生成水のアルカリ度合もチェックする事ができるもので、この場合、スイッチＳＷ２をオンして検知対象液内に水道水の塩素濃度のチェックと同様にヘッド部７を浸ければよい。
【００４１】
つまりスイッチＳＷ２のオン動作に連動してスイッチＳＷ２１がオンし、演算増幅器ＯＰ３の非反転入力端の電圧が、抵抗Ｒ８と可変抵抗器ＶＲ２で分圧された電圧に切り換えられるため、塩素濃度測定時に比して演算増幅器ＯＰ３の出力端の電位が接続ラインＡの電位よりもマイナス方向に低くなる。
【００４２】
一方アルカリ測定時においては電極３ａ、３ｂ間の起電圧の方向が塩素濃度測定時とは反対方向となり、アルカリ度合が高くなれば成る程、演算増幅器ＯＰ２の非反転入力端に入力する検出信号電圧は接続ラインＡの電位に対してマイナス方向に大きくなる。
【００４３】
ここでアルカリ度合が所定以上高い場合には発光ダイオードＬ１〜Ｌ５を全点灯させ、アルカリ度合が所定度合より低い場合には全消灯させるように、上記演算増幅器ＯＰ３の出力端の電位を、可変抵抗器ＶＲ２により設定しておくことにより、アルカリ度合が所定以上高い程と、演算増幅器ＯＰ３の非反転入力端に入力する検出信号電圧が接続ラインＡを基準としてマイナス方向に増大するが、演算増幅器ＯＰ３の出力端の電位を接続ラインＡの電位よりもマイナス方向に十分大きくすることで、検知信号が入力する演算増幅器ＯＰ２の非反転入力端と、グランド（基準電位）との間の電位差が小さくなり、演算増幅器ＯＰ２の出力端から出力される増幅された検出信号電圧は接続ラインＡの電圧に対して略近い値となる。これによって、アルカリ度合が所定以上ある場合には、全てのコンパレータＣＰ１〜ＣＰ５の非反転入力端の入力電圧が基準電圧を下回って、コンパレータＣＰ１〜ＣＰ５の出力が全て”Ｌ”レベルとなり、全発光ダイオードＬ１〜Ｌ５が点灯する。
【００４４】
また検知対象の液のアルカリ度合が低くなれば成る程、マイナス方向の起電圧が小さくなり、演算増幅器ＯＰ２の非反転入力端に入力するマイナス方向の検出信号電圧は小さくなり、演算増幅器ＯＰ２の非反転入力端と、グランド（基準電位）との間の電位差が大きくなり、演算増幅器ＯＰ３の出力端から出力される増幅された検出信号電圧は大きくなる。従って被測定液のアルカリ度合が高ければ高い程、非反転入力端の電圧が基準電圧を越えるコンパレータの数が多くなって、発光する発光ダイオードの数が少なくなる。つまり発光ダイオードＬ１〜Ｌ５の全てが点灯している場合にはアルカリ度合が所定以上あって水質評価が”良”で、逆にその点灯数が少なくなればなるほどアルカリ度合が小さくなって水質評価が”悪”となっていることが分かる。
【００４５】
尚本実施形態では発光ダイオードＬ１〜Ｌ５の点灯数で水質評価を表示するようになっているが、液晶表示器等を用いて表示するようにしても良い。
【００４６】
【発明の効果】
請求項１の発明は、電源と、異種の金属により構成され、検知対象の液中に浸けられたときに電圧を発生して検知信号として出力する一対の電極と、塩素濃度の検知対象の液中に浸けたときに起電圧のマイナス側となり、アルカリ度合の検知対象の液中に浸けたときに起電圧のプラス側となる一方の電極を接続する接続ラインの電位を上記電源のマイナスグランドから見て一定の電位に保持する手段と、上記検知信号を非反転入力端に入力し、出力端と反転入力端に接続した抵抗と反転入力端と基準電位との間に接続した抵抗とで定まる利得で検知信号を非反転増幅する信号増幅用の第１演算増幅器と、上記電源のプラス極と上記接続ラインとの間に接続された複数の抵抗の直列回路によって構成される分圧回路から出力される複数の異なる分圧出力に対応して設けられて、異なる分圧出力により基準電圧が夫々設定され、該基準電圧と上記第１演算増幅器から出力される検知信号電圧とを比較する複数のコンパレータと、該各コンパレータに対応して設けられて各コンパレータの出力端と上記電源との間に接続され、上記対応するコンパレータの出力に応じて駆動され、検知結果を表示する表示手段とを備えるとともに、塩素濃度測定時には上記基準電位を上記接続ラインの電位とし、アルカリ度合測定時には上記基準電位を上記接続ラインの電位よりもマイナス方向に低く切換設定する手段を備えて、測定するアルカリ度合が所定以上高い場合から所定以下に至るまでの上記第１演算増幅器から出力される検知信号電圧の変化と、測定する塩素濃度が略零の場合から所定濃度以上に至るまでの上記第１演算増幅器から出力される検知信号電圧の変化が略同じとなるように上記第１演算増幅器の利得を設定したので、水道水の塩素濃度の略零の場合から所定濃度に至るまでの水質の評価表示と、アルカリ生成水などアルカリ度合の所定以上から所定以下に至るまでの水質の評価表示とが同じ表示手段により行うことができ、しかもコンパレータ等を切替えることなく行えるため、同一の電極と簡単な回路構成により塩素濃度の測定と、アルカリ度合の測定とが行える水質チェッカ回路を実現できるという効果がある。
【００４７】
請求項２の発明は、請求項１の発明において、上記接続ラインの電位を一定に保持する手段を、上記電源の電圧を所定電圧に降圧した電圧を非反転入力端に入力して略同じ電圧を出力に発生するように利得が設定された非反転増幅器を構成する第２演算増幅器により構成し、該第２演算増幅器の出力端に上記接続ラインを接続してあるので、接続ラインの電位を一定に保持する回路が簡単に実現できる。
【００４８】
請求項３の発明は、請求項１又は２の発明において、上記切換手段として、反転入力端と出力端が接続された第３演算増幅器と、該第３演算増幅器の非反転入力端に入力する電圧を上記接続ラインの電圧とこの接続ラインよりも低い電圧とに切り換える電圧切換手段とから構成し、上記第３演算増幅器の出力端の電位を上記基準電位としたので、演算増幅器と、簡単な電圧切換手段とで、塩素濃度測定時とアルカリ度合の測定時とを同じ信号増幅用の第１演算増幅器と、コンパレータと、同じ表示手段によって、同じように水質の評価表示が行える回路を実現できる。
【００４９】
請求項４の発明は、請求項１乃至３の何れかの発明において、上記各コンパレータの非反転入力端に上記信号増幅用の第１演算増幅器からの検知信号電圧を、上記各コンパレータの反転入力端に基準電圧を夫々入力し、基準電圧より入力する検知信号電圧が低いコンパレータをオンして上記表示手段を動作させるので、塩素濃度測定時に測定前の動作チェックができるという効果がある。
【００５０】
請求項５の発明では、請求項１乃至４の何れかの発明において、上記電源が電池電源を安定化する定電圧回路の出力により構成してあるので、電池電源によって動作する水質チェッカ回路を提供できる。
【図面の簡単な説明】
【図１】本発明の一実施形態の回路図である。
【図２】同上を使用した水質チェッカの側面図である。
【図３】（ａ）は同上を使用した水質チェッカのヘッド部の一部省略せる拡大断面図である。
（ｂ）は同上を使用した水質チェッカのヘッド部の一部省略せる拡大側面図である。
【符号の説明】
１電池電源
２定電圧回路
３ａ、３ｂ電極
４表示回路
ＯＰ１〜ＯＰ３演算増幅器
ＳＷ１、ＳＷ２、ＳＷ２１スイッチ
ＣＰ１〜ＣＰ５コンパレータ
Ｌ１〜Ｌ５発光ダイオード[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a water quality checker circuit that can be used for checking either the chlorine concentration of tap water or the alkalinity of alkali-generated water.
[0002]
[Prior art]
Although there are those that check the chlorine concentration or alkalinity in the conventional liquid by the electromotive voltage of a pair of electrodes, the direction of the electromotive voltage between the electrodes is opposite when measuring the chlorine concentration and when measuring the alkalinity Therefore, when the chlorine concentration is almost zero, that is, when clean water and a liquid with a certain alkalinity level or higher are both evaluated as “good”, the same LED is used for evaluation display When trying to do so, there is a problem that the circuit configuration for detection signal processing becomes complicated because the direction of the electromotive voltage is reversed.
[0003]
[Problems to be solved by the invention]
The present invention has been made in view of the above-mentioned problems. The purpose of the present invention is to check both the alkalinity and the chlorine concentration, and when the water quality is evaluated and displayed by the display means, It is an object of the present invention to provide a water quality checker circuit that can be evaluated and displayed by the same display means at the time of measuring either concentration or alkalinity.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, the power source and the pair of electrodes that are made of different metals and generate a voltage and output as a detection signal when immersed in the liquid to be detected. And a connection line that connects one of the electrodes that becomes the negative side of the electromotive voltage when immersed in the liquid whose chlorine concentration is to be detected and the positive side of the electromotive voltage when immersed in the liquid whose alkalinity is to be detected Means for holding the potential at a constant potential as viewed from the negative ground of the power source, and the detection signal is input to the non-inverting input terminal, and the resistor and the inverting input terminal are connected to the output terminal and the inverting input terminal. Reference potential For signal amplification that non-inverts and amplifies the detection signal with a gain determined by a resistor connected between First Provided corresponding to a plurality of different voltage dividing outputs outputted from an operational amplifier and a voltage dividing circuit constituted by a series circuit of a plurality of resistors connected between the positive pole of the power source and the connection line. , Each reference voltage is set by a different divided voltage output, the reference voltage and the above First A plurality of comparators for comparing the detection signal voltages output from the operational amplifiers, provided corresponding to the comparators, connected between the output terminals of the comparators and the power supply, and output to the corresponding comparators And display means for displaying the detection result. And salt When measuring elementary concentration Above reference potential Use the potential of the above connection line when measuring the alkalinity. Above reference potential Provided with means for switching setting in the negative direction lower than the potential of the connection line , From when the alkalinity to be measured is higher than a predetermined level to below a predetermined level Change of the detection signal voltage output from the first operational amplifier of The above from the case where the chlorine concentration to be measured is approximately zero to the predetermined concentration or more First Output from operational amplifier Is So that the change in the detection signal voltage is approximately the same. First The gain of the operational amplifier is set.
[0005]
According to a second aspect of the present invention, in the first aspect of the invention, the means for holding the potential of the connection line constant is substantially the same voltage by inputting a voltage obtained by stepping down the voltage of the power source to a predetermined voltage to the non-inverting input terminal. Configures a non-inverting amplifier with gain set to generate at the output Second Comprising an operational amplifier, Second The connection line is connected to the output terminal of the operational amplifier.
[0006]
In the invention of claim 3, in the invention of claim 1 or 2, an inverting input terminal and an output terminal are connected as the switching means. Third An operational amplifier; and Third Voltage switching means for switching the voltage input to the non-inverting input terminal of the operational amplifier between the voltage of the connection line and a voltage lower than the connection line; Third The potential at the output terminal of the operational amplifier Above reference potential It is characterized by that.
[0007]
According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the signal amplifying signal is connected to the non-inverting input terminal of each of the comparators. First A detection signal voltage from an operational amplifier is inputted to each inverting input terminal of each comparator, and a comparator having a lower detection signal voltage input than the reference voltage is turned on to operate the display means. .
[0008]
According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the power source is constituted by an output of a constant voltage circuit that stabilizes the battery power source.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to an embodiment.
[0010]
FIG. 1 shows a circuit of this embodiment. In FIG. 1, a parallel circuit of a chlorine concentration measurement start switch SW1 and an alkalinity measurement start switch SW2 is provided for a battery power source 1 such as a dry battery or a secondary battery. A constant voltage circuit 2 composed of a general-purpose IC or the like is connected to the power supply, a stabilized power supply voltage is obtained by the constant voltage circuit 2, and this voltage is divided by a resistance voltage dividing circuit of resistors R1 and R2, thereby forming a non-inverting amplifier. Operational amplifier OP1 (Second operational amplifier) A display for displaying the middle point potential of the series circuit of the resistors R3 and R4 connected between the output terminal and the inverting input terminal of the operational amplifier OP1 in stages for the water quality evaluation. The ground level of the reference voltage of the comparators CP1 to CP5 of the circuit 4 is set to the ground level of the detection signal voltage due to the electromotive force generated between the sensor electrodes 3a and 3b.
[0011]
A series circuit of resistors R5 and R6 is connected between the electrodes 3a and 3b, and the midpoint of the series circuit is an operational amplifier OP2 for amplifying a detection signal. (First operational amplifier) Is connected to the non-inverting input terminal. This non-inverting input terminal is also connected to the positive pole side of the output terminal of the constant voltage circuit 2 via the capacitor C1.
[0012]
The operational amplifier OP2 constitutes a non-inverting amplifier, and a parallel circuit composed of a variable resistor VR1 and a response adjusting capacitor C2 is connected between the output end and the inverting input end. The resistance of the variable resistor VR1 A gain is set by a value and a resistor R7 connected between an inverting input terminal and an output terminal of an operational amplifier OP3 (to be described later) serving as a ground (reference), and the gain can be adjusted by a variable resistor VR1. It has become.
[0013]
On the other hand, a series circuit of the variable resistor VR2 and the switch SW21 is connected between the midpoint of the series circuit of the resistors R3 and R4 and the negative pole of the battery power source 1 through the resistor R8, and the variable resistor VR2 , A noise removing capacitor C3 is connected to the series circuit of the switch SW21, and a non-inverting input terminal of the operational amplifier OP3 is connected to a connection point between the resistor R8 and the variable resistor VR2.
[0014]
This operational amplifier OP3 (Third operational amplifier) Constitutes a voltage follower non-inverting amplifier, the input voltage of the non-inverting input terminal is equal to the output voltage, and the output terminal is connected to the inverting input terminal of the operational amplifier OP2 via the resistor R7. OP2 ground potential (Reference potential) Is set to the potential of the output terminal.
[0015]
The switch SW21 is a switch that is turned on / off in conjunction with the on / off of the alkalinity measurement start switch SW2, and constitutes a switching means for the input voltage of the operational amplifier OP2.
[0016]
The display circuit 4 comprises five comparators CP1 to CP5 and display means connected between the output terminals of the comparators CP1 to CP5 and the positive pole of the output terminal of the constant voltage circuit 2 via current limiting resistors R11 to R15. It comprises light emitting diodes L1 to L5 and the like. A voltage dividing circuit comprising a series circuit of resistors R16 to R21 having the same resistance value is connected between the positive pole at the output terminal of the constant voltage circuit 2 and the midpoint of the series circuit of the resistors R3 and R4, The divided voltage at the connection point between R21 and the resistor R20 is connected as a reference voltage to the inverting input terminal of the comparator CP1, and the divided voltage at the connection point between the resistor R20 and the resistor R19 is connected to the inverting input terminal of the comparator CP2. And the divided voltage at the connection point between the resistors R19 and R18 is connected as a reference voltage to the inverting input terminal of the comparator CP3. Similarly, the divided voltage at the connection point between the resistors R18 and R17 is connected to the comparator CP4. Is connected as a reference voltage to the inverting input terminal, and a divided voltage at the connection point between the resistor R17 and the resistor R16 is connected as a reference voltage to the inverting input terminal of the comparator CP5. Comparator from the reference voltage CP1 to the reference voltage of the comparator CP5 are sequentially stepwise increased.
[0017]
On the other hand, the output terminals of the operational amplifier OP2 are connected to the non-inverting input terminals of the comparators CP1 to CP5 through the resistors R22 to R26, respectively, and the resistors R22 to R26 having the same resistance value are used. .
[0018]
FIG. 2 shows the external appearance of a water quality checker using the water quality checker circuit of the present invention. A housing 5 made of a resin molded product includes the circuit and battery power source 1 shown in FIG. 1 and switches SW1 and SW2 on the outer surface. And a pair of electrodes 3a at the tip part formed so as to protrude forward from the front part of the main body part 6 and the main body part 6 in which the light emitting parts of the light emitting diodes L1 to L5 of the display circuit 4 are exposed. , 3b and a head portion 7 provided with a sensor portion.
[0019]
The housing 5 is preferably formed of a material that does not contain an exogenous endocrine disrupting chemical substance (environmental hormone), and is formed of a resin molded product such as an ABS resin.
[0020]
Further, the head portion 7 is formed in a cylindrical shape that is long in the front-rear direction, and the hollow portion inside thereof communicates with the main body portion 6 on the rear end side, and the front end side opens forward. Here, at the front end portion of the head portion 7, as shown in FIG. 4, a cylinder that protrudes forward over the entire circumference of the opening and has an outer diameter smaller than the outer diameter of the head portion 7. A fitting rib 8 is provided on the outer peripheral surface of the fitting rib 8, and a fitting recess 9 is provided over the entire circumference. 9 is formed as a fitting convex portion 10 that protrudes to the outer peripheral side from 9.
[0021]
A fixing member 11 for securing the watertightness inside and outside the head portion 7 and fixing the terminal electrodes 3a and 3b is mounted at the tip portion of the head portion 7. The fixing member 11 is preferably formed of a material that does not contain environmental hormones. For example, the fixing member 11 is formed of a resin molded product such as ABS resin, and the front end side of the locking portion 12 formed in a cylindrical shape. A cylindrical protruding portion 13 having a smaller diameter than the locking portion 12 is formed on the rear end, and a cylindrical insertion portion 14 having a smaller diameter than the locking portion 12 is formed on the rear end side of the locking portion 12.
[0022]
At this time, the projecting portion 13 is formed with a front concave portion 15 that opens forward, and the insertion portion 14 is formed with a rear concave portion 22 that opens rearward. The front concave portion 15, the rear concave portion 22, Is partitioned by a locking portion 12.
[0023]
In addition, the engaging portion 12 is formed with two insertion holes 16 that allow the front concave portion 15 and the rear concave portion 22 to communicate with each other. Further, a concave groove 17 is formed on the outer peripheral surface of the insertion portion 14 of the fixing member 11 over the entire circumference.
[0024]
The fixing member 11 is attached to the front end of the head portion 7 by inserting the insertion portion 14 from the front end opening of the head portion 7 of the housing 5 as shown in FIG. By attaching 18, water tightness between the outer surface of the insertion portion 14 and the inner surface of the head portion 7 can be ensured.
[0025]
Furthermore, the fixing member 11 is firmly attached to the head portion 7 by filling the gap between the outer surface of the insertion portion 14 and the inner surface of the head portion 7 with an adhesive and bonding the head portion 7 and the fixing member 11. In addition, the watertightness between the outer surface of the insertion portion 14 and the inner surface of the head portion 7 can be further improved.
[0026]
Two lead wires 19a and 19b are disposed in the hollow portion of the head portion 7, and the rear end portions of the lead wires 19a and 19b are drawn out to the main body portion 6 of the housing 5 and connected to the control portion. The front end is fixed to the fixing member 11. Electrodes 3a and 3b are connected to the tips of the two lead wires 19a and 19b, respectively.
[0027]
Here, the lead wires 19 a and 19 b are inserted into the insertion holes 16 of the locking portion 12 of the fixing member 11, and the rear end side is located behind the fixing member 11 through the rear end opening from the rear concave portion 22 of the insertion portion 14. Has been pulled out. In addition, a spherical knob 20 larger than the inner diameter of the insertion hole 16 is formed at the end of the tip of the lead wires 19a and 19b, and the tip of the lead wires 19a and 19b is formed on the front side of the protrusion 13 by the knob 20. The recess 15 is locked to the front side of the locking portion 12. The rear ends of the linear electrodes 3a and 3b are embedded in the ridges 20 at the ends of the lead wires 19a and 19b, respectively, whereby the electrodes 3a and 3b are connected to the ends of the lead wires 19a and 19b. Yes. Each electrode 3 a, 3 b is disposed so that the tip side protrudes forward from the opening of the front recess 15 of the protrusion 13 of the fixing member 11.
[0028]
Further, the sealing member 21 is filled in the rear concave portion 22 of the insertion portion 14 of the fixing member 11, whereby the lead wires 19 a and 19 b are fixed in the rear concave portion 22 of the insertion portion 14 of the fixing member 11. ing. Further, the sealing material 23 is also filled in the front concave portion 15 of the protruding portion 13 of the fixing member 11, whereby the electrodes 3 a and 3 b are fixed in the front concave portion 15 of the protruding portion 13 of the fixing member 11. . Further, the sealing materials 23 and 19 ensure water tightness between the front end side and the rear end side of the fixing member 11.
[0029]
In the pair of electrodes 3a and 3b, one electrode 3b is formed of a platinum wire and the other electrode 3a is formed of a silver wire, and a sensor portion is configured by the electrodes 3a and 3b. Each electrode 3a, 3b is formed as a buried portion embedded in the sealing material 23 in the front recess 15 of the protruding portion 13 of the fixing member 11, and the front end side is forward from the sealing material 23. It is formed as a detection part which protrudes toward.
[0030]
The electrode 3a made of silver wire is formed with a silver chloride coating only on the surface of the detection terminal portion 7, and no silver chloride coating is formed on the surface of the buried portion. For this reason, the electrode 3a and the lead wire 19a The silver chloride coating is not formed on the connection portion between the electrode 3a and the lead wire 19a, and the electrical connection between the electrode 3a and the lead wire 19a is not hindered by the silver chloride coating.
[0031]
Furthermore, a cap body 24 is provided at the tip of the head portion 7 so as to cover the fixing member 11 and the detection terminal portions 7 of the electrodes 3a and 3b, whereby the detection terminal portion 7 is protected. As shown in FIG. 3, the cap body 24 is formed in a bottomed cylindrical shape with the front end closed and the rear end opened, and the outer diameter is substantially the same as the outer diameter of the head portion 7. The Further, the rear end portion of the cap body 24 is formed as a fitted rib 25 having an inner diameter larger than that of the front end side and substantially the same as the outer diameter of the locking portion 12 of the fixing member 11. On the inner peripheral surface of the rear end portion of the fitting rib 25, a fitting concave portion 26 that matches the fitting convex portion 10 of the fitting rib 8 of the head portion 7 is formed over the entire circumference. Further, the rear end side of the fitting recessed portion 26 is formed as a fitting convex portion 27 that protrudes to the inner peripheral side of the fitting concave portion 26 and matches the fitting concave portion 9 of the fitting rib 8. Yes. And the to-be-fitted rib 25 of the cap body 24 is arrange | positioned from the outer peripheral side of the latching | locking part 12 of the fixing member 11 to the outer peripheral side of the fitting rib 8 of the head part 7, and the fitting recessed part 9 and the to-be-fitted convex part 27 are arranged. The cap body 24 is attached to the front end of the head portion 7 by fitting the fitting convex portion 10 and the fitting concave portion 26 together. At this time, the fitting rib 8 and the fitting portion are fitted. The gap between the ribs 25 is filled with an adhesive and the cap body 24 and the head portion 7 are bonded to firmly fix the cap body 24 to the head portion 7 and to be fitted to the fitting rib 8. The watertightness between the ribs 25 can be ensured.
[0032]
The cap body 24 is formed with two parallel and parallel slit-shaped openings 28, and the inside and the outside of the cap body 24 communicate with each other through the openings 28. The opening 28 is formed so as to extend from the side surface of the cap body 24 through the front end surface to the opposite side surface. Further, the cap body 24 is formed with communication holes 29 at both ends of each opening portion 28 so as to communicate with the opening portion 28 and between the inside and the outside of the cap body 24. The diameter is larger than the width of the portion 28.
[0033]
The slit-shaped opening 28 of the cap body 24 allows the liquid to be detected such as tap water to enter the inside of the cap body 24 when measuring the water quality, so that the detection terminal portion 7 of the electrode 2 is immersed in the liquid. The liquid is discharged from the inside of the cap body 24 after measuring the water quality.
[0034]
Further, the communication hole 6 discharges air from the inside of the cap body 24 when measuring the water quality so that the liquid to be detected smoothly enters the inside of the cap body 24, or air inside the cap body 24 after measuring the water quality. This allows the liquid to be smoothly discharged from the inside of the cap body 24.
[0035]
Next, the operation of the water quality checker circuit of this embodiment will be described.
[0036]
First, when checking the chlorine concentration of tap water, the switch SW1 is turned on to immerse the head unit 7 in tap water that is the liquid to be detected. An electromotive voltage is generated between the electrodes 3a and 3b in the cap body 24 immersed in tap water according to the chlorine concentration. In this case, the electrode 3a becomes a positive pole, and a voltage is generated in the resistor R6 due to the electromotive voltage. This voltage is input to the operational amplifier OP2 at the non-inverting input terminal as a detection signal, and is amplified non-invertingly.
[0037]
On the other hand, the output voltage from the constant voltage circuit 2 is divided and reduced by the resistor R1 and the resistor R2, and the voltage across the resistor R2 is non-inverted and amplified by the operational amplifier OP1. Here, the resistance values of the resistors R4 and R3 connected to the output terminal and the inverting input terminal of the operational amplifier OP1 are input so that the voltage of the connection line A connected to the middle point is substantially equal to the voltage of both ends of the resistor R2. It is set to be a voltage.
[0038]
Since the switch SW21 is in the OFF state, the voltage at the output terminal of the operational amplifier OP3 is equal to the voltage input to the non-inverting input terminal, that is, the voltage of the connection line A. Therefore, since the potential of the output terminal is equal to the potential of the connection line A, the operational amplifier OP2 has a resistance value of the variable resistor VR1 and a resistor R7 connected between the inverting input terminal and the output terminal of the operational amplifier OP3. The detection signal voltage generated at both ends of the resistor R6 is amplified by a gain determined by the resistance value.
[0039]
The detection signal voltage amplified by the operational amplifier OP3 is input to the display circuit 4 and compared with reference voltages set in the comparators CP1 to CP5. In the comparator in which the detection signal voltage does not exceed the reference voltage, the output terminal is set to the “L” level, and a light emission current is passed through the light emitting diode connected to the output terminal. In other words, the higher the chlorine concentration in the water to be measured, the higher the electromotive voltage generated between the electrodes 3a and 3b, and the higher the voltage across the resistor R6. Therefore, the number of comparators exceeding the reference voltage increases, and the light emission The number of light emitting diodes to be reduced is reduced. Therefore, when all of the light emitting diodes L1 to L5 are lit, the chlorine concentration is nearly zero and the water quality evaluation is “good”. The smaller the number of lighting, the higher the chlorine concentration is, and the water quality evaluation is “bad”. " Further, before immersing the head part 7 in tap water, the capacitor C1 is charged from the time when the switch SW1 is turned on, and the light emitting diodes L1 to L5 are sequentially lighted sequentially with the charging, and the operation check can be performed by this lighting. It is like that. This operation is only at the time of measuring the chlorine concentration, and this lighting operation is not performed at the time of measuring the alkalinity described later.
[0040]
The checker circuit of the present invention can check the alkalinity of the alkali generated water in addition to the chlorine concentration of tap water. In this case, the switch SW2 is turned on to check the chlorine concentration of tap water in the detection target liquid. It is sufficient to immerse the head portion 7 in the same manner as described above.
[0041]
In other words, the switch SW21 is turned on in conjunction with the ON operation of the switch SW2, and the voltage at the non-inverting input terminal of the operational amplifier OP3 is switched to the voltage divided by the resistor R8 and the variable resistor VR2, so when measuring the chlorine concentration In comparison, the potential at the output terminal of the operational amplifier OP3 is lower than the potential of the connection line A in the negative direction.
[0042]
On the other hand, in the alkali measurement, the direction of the electromotive voltage between the electrodes 3a and 3b is opposite to that in the chlorine concentration measurement, and as the alkalinity increases, the detection signal voltage input to the non-inverting input terminal of the operational amplifier OP2. Increases in the negative direction with respect to the potential of the connection line A.
[0043]
Here, the potential of the output terminal of the operational amplifier OP3 is set to a variable resistance so that the light emitting diodes L1 to L5 are all turned on when the alkalinity is higher than a predetermined level, and are turned off when the alkalinity is lower than the predetermined level. As the alkalinity is higher than a predetermined value by setting the voltage VR2, the detection signal voltage input to the non-inverting input terminal of the operational amplifier OP3 increases in the minus direction with reference to the connection line A. However, the operational amplifier OP3 Is made sufficiently larger in the minus direction than the potential of the connection line A, the non-inverting input terminal of the operational amplifier OP2 to which the detection signal is input, and the ground (Reference potential) And the amplified detection signal voltage output from the output terminal of the operational amplifier OP2 is substantially close to the voltage of the connection line A. Accordingly, when the alkalinity is equal to or higher than a predetermined level, the input voltages at the non-inverting input terminals of all the comparators CP1 to CP5 are lower than the reference voltage, and all the outputs of the comparators CP1 to CP5 are set to the “L” level. The diodes L1 to L5 are lit.
[0044]
Further, the lower the alkalinity of the liquid to be detected, the smaller the negative electromotive voltage, the smaller the negative detection signal voltage input to the non-inverting input terminal of the operational amplifier OP2, and the lower the operational amplifier OP2. Inverting input and ground (Reference potential) And the amplified detection signal voltage output from the output terminal of the operational amplifier OP3 increases. Therefore, the higher the alkalinity of the solution to be measured, the more comparators whose non-inverting input voltage exceeds the reference voltage, and the fewer light emitting diodes emit light. That is, when all of the light emitting diodes L1 to L5 are lit, the alkalinity level is more than a predetermined value and the water quality evaluation is “good”. Conversely, the lower the number of lightings, the lower the alkalinity level and the water quality evaluation becomes. It turns out that it is "evil".
[0045]
In this embodiment, the water quality evaluation is displayed by the number of lighting of the light emitting diodes L1 to L5, but may be displayed using a liquid crystal display or the like.
[0046]
【The invention's effect】
The invention of claim 1 comprises a power source, a pair of electrodes that are made of different kinds of metals, generate a voltage and output as a detection signal when immersed in the liquid to be detected, and a liquid for detecting the chlorine concentration From the negative ground of the power supply, the potential of the connection line that connects one electrode that becomes the negative side of the electromotive voltage when immersed in the solution and becomes the positive side of the electromotive voltage when immersed in the liquid whose alkalinity is detected Means for holding at a constant potential, and the detection signal is input to the non-inverting input terminal, and the resistance connected to the output terminal and the inverting input terminal and the inverting input terminal Reference potential For signal amplification that non-inverts and amplifies the detection signal with a gain determined by a resistor connected between First Provided corresponding to a plurality of different voltage dividing outputs outputted from an operational amplifier and a voltage dividing circuit constituted by a series circuit of a plurality of resistors connected between the positive pole of the power source and the connection line. , Each reference voltage is set by a different divided voltage output, the reference voltage and the above First A plurality of comparators for comparing the detection signal voltages output from the operational amplifiers, provided corresponding to the respective comparators, connected between the output terminals of the respective comparators and the power supply, and output to the corresponding comparators And a display means that is driven in response to display the detection result. ,salt When measuring elementary concentration Above reference potential Use the potential of the above connection line when measuring the alkalinity. Above reference potential Provided with means for switching setting in the negative direction lower than the potential of the connection line , From when the alkalinity to be measured is higher than a predetermined level to below a predetermined level Change of the detection signal voltage output from the first operational amplifier of The above from the case where the chlorine concentration to be measured is approximately zero to the predetermined concentration or more First Operational amplifier Output from The above so that the change of the detection signal voltage is almost the same First Since the gain of the operational amplifier is set, the water quality evaluation display from the case where the chlorine concentration of tap water is almost zero to the predetermined concentration, and the water quality from the predetermined degree of alkalinity such as alkali generated water to below the predetermined level Since the evaluation display can be performed by the same display means and without changing the comparator, etc., a water quality checker circuit that can measure the chlorine concentration and the alkalinity with the same electrode and simple circuit configuration is realized. There is an effect that can be done.
[0047]
According to a second aspect of the invention, in the first aspect of the invention, the means for holding the potential of the connection line constant is substantially the same voltage by inputting a voltage obtained by stepping down the voltage of the power source to a predetermined voltage to the non-inverting input terminal. Configures a non-inverting amplifier with gain set to generate at the output Second Comprising an operational amplifier, Second Since the above connection line is connected to the output terminal of the operational amplifier, Connection line It is possible to easily realize a circuit that keeps the potential at a constant.
[0048]
According to a third aspect of the present invention, in the first or second aspect of the present invention, the inverting input terminal and the output terminal are connected as the switching means. Third An operational amplifier; and Third Voltage switching means for switching the voltage input to the non-inverting input terminal of the operational amplifier between the voltage of the connection line and a voltage lower than the connection line; Third The potential at the output terminal of the operational amplifier Above reference potential As a result, the operational amplifier and simple voltage switching means can be used for the same signal amplification when measuring the chlorine concentration and when measuring the alkalinity. First A circuit capable of displaying and evaluating the water quality in the same manner can be realized by the operational amplifier, the comparator, and the same display means.
[0049]
According to a fourth aspect of the present invention, there is provided the signal amplification circuit according to any one of the first to third aspects, wherein the signal amplifying circuit is connected to a non-inverting input terminal of each comparator. First Chlorine concentration measurement because the detection signal voltage from the operational amplifier is input to the inverting input terminal of each comparator, and the display means is operated by turning on the comparator whose detection signal voltage is lower than the reference voltage. Sometimes it is possible to check the operation before measurement.
[0050]
According to a fifth aspect of the present invention, there is provided a water quality checker circuit that is operated by a battery power source because the power source is constituted by the output of a constant voltage circuit that stabilizes the battery power source. it can.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of an embodiment of the present invention.
FIG. 2 is a side view of a water quality checker using the same as above.
FIG. 3A is an enlarged cross-sectional view in which a part of a head portion of a water quality checker using the same can be omitted.
(B) is an enlarged side view in which a part of the head portion of the water quality checker using the above can be omitted.
[Explanation of symbols]
1 Battery power
2 Constant voltage circuit
3a, 3b electrode
4 Display circuit
OP1 to OP3 operational amplifier
SW1, SW2, SW21 switch
CP1 to CP5 comparator
L1-L5 Light emitting diode

Claims

A power source and a pair of electrodes that are made of different metals and generate a voltage when immersed in the liquid to be detected and output as a detection signal, and occur when immersed in the liquid whose chlorine concentration is to be detected. Holds the potential of the connection line connecting one electrode, which becomes the positive side of the electromotive voltage when immersed in the liquid to be detected for alkalinity, at a constant potential when viewed from the negative ground of the power source. The detection signal is non-inverted with a gain determined by a means for inputting the detection signal to the non-inverting input terminal and a resistor connected between the output terminal and the inverting input terminal and a resistance connected between the inverting input terminal and the reference potential. A plurality of different voltage division outputs from a voltage dividing circuit constituted by a first operational amplifier for signal amplification to be amplified and a series circuit of a plurality of resistors connected between the positive pole of the power source and the connection line Corresponding to the output Vignetting, the different reference voltages by the divided output is respectively set, and a plurality of comparators for comparing the detection signal voltage output from the reference voltage and the first operational amplifier provided corresponding to the respective comparator Te is connected between the output terminal and the power supply of the comparators are driven in response to the output of the corresponding comparator, the detection result provided with a display means for displaying said the reference potential at the time chlorine concentration measurement the potential of the connection line, at the time of alkaline degree measuring comprises means for switching set low in the negative direction than the potential of the connection line the reference potential, said to alkaline degree of measurement reaches the predetermined or less from when the predetermined or more high the change of the detection signal voltage output from the first operational amplifier, said from when the chlorine concentration is substantially zero measuring up to more than a predetermined concentration Water checker circuit, wherein a change in the detection signal voltage that will be output from the first operational amplifier sets the gain of the first operational amplifier so as to be substantially the same.

The non-inverted gain is set so that a voltage obtained by stepping down the voltage of the power source to a predetermined voltage is input to the non-inverted input terminal to generate substantially the same voltage at the output. constituted by a second operational amplifier constituting the amplifier, water quality checker circuit according to claim 1, characterized in that formed by connecting the connecting line to the output terminal of the second operational amplifier.

As the switching means, a third operational amplifier output terminal and the inverting input terminal is connected, the third non-inverting input voltage of the connection line the voltage input to the terminal of the operational amplifier and a voltage lower than the connection line The water quality checker circuit according to claim 1 or 2, wherein the reference voltage is used as the potential at the output terminal of the third operational amplifier.

The detection signal voltage from the first operational amplifier for signal amplification is input to the non-inverting input terminal of each comparator, the reference voltage is input to the inverting input terminal of each comparator, and the detection signal voltage input is lower than the reference voltage. 4. The water quality checker circuit according to claim 1, wherein a comparator is turned on to operate the display means.

5. The water quality checker circuit according to claim 1, wherein the power source is constituted by an output of a constant voltage circuit for stabilizing the battery power source.