JP3606169B2

JP3606169B2 - Capacitive moisture sensor

Info

Publication number: JP3606169B2
Application number: JP2000201621A
Authority: JP
Inventors: 淳之広野; 秀夫森; 裕司高田
Original assignee: Matsushita Electric Works Ltd
Current assignee: Panasonic Electric Works Co Ltd
Priority date: 2000-07-03
Filing date: 2000-07-03
Publication date: 2005-01-05
Anticipated expiration: 2020-07-03
Also published as: JP2002022697A

Description

【０００１】
【発明の属する技術分野】
本発明は、水分量の検出や水分の有無を検出する静電容量式水分量センサに関するものである。
【０００２】
【従来の技術】
従来から水分量を測定する方法は、一般には大別すると、赤外線吸収式、マイクロ波式、電気抵抗式、静電容量式、重量式などがある。
【０００３】
しかし、上記の赤外線吸収式において透過赤外光を用いる水分量センサでは、検知対象物が赤外光を透過するような材質のものでなければならない。この場合、数ｍｍ程度までの薄い紙等には適するが、赤外光を透過させない材質のものには不向きである。さらに反射赤外光を用いる水分量センサでは、検知対象物の表面の凹凸状態、色によって反射条件が大きく左右される。つまり、照射光量に対する光量減少量が水分の吸収によるのか反射条件によるのかが定まらず、精度の良い水分量検知ができないという問題があった。
【０００４】
また、マイクロ波式は、複素誘電率によって発生する伝播エネルギ損失量を測定しているため、装置が複雑となって製作コストが高いという問題があった。
【０００５】
更に電気抵抗式は、水の電気抵抗式は、水の電気伝導度を用いた抵抗成分の測定を行う方法だが、実際は水分中に含まれる不純物、例えば塩分（ＮａＣｌ）などが電気分解によってできたイオン伝導度の方が桁違いに大きく、そのため抵抗で測定できる値は、正確には水分中に溶解している不純物濃度が実際のところである。
【０００６】
更にまた重量式は、その測定原理からオンライン計測には不向きな方法である。
【０００７】
一方静電容量式は比誘電率が水と同等なものが存在すると誤差の要因となるが、比誘電率が２０〜５０の有機溶剤系物質を含まない上記用途（発酵工程・米等の穀類・茶の葉・タバコの葉・生ゴミ・木材・土壌・コンクリート細骨材、等で、夫々が静止或いは移動している状態で夫々の物質に含まれる水分量をオンライン又はオフラインで検出する場合や、雨検知・バスお湯はり時の水位監視・人体の着席検知等）中に存在する物質では水と同等の比誘電率を有するものがないため、誤差の少ない水分量検知ができ、しかも検知対象物に対して接触させて検知対象物中の水分量を検知できる特徴がある。
【０００８】
この静電容量式の原理は、水が分極する物質（誘電体）である性質を用いて、図２２に示すように一対の電極１００ａ，１００ｂ間の静電容量値を測定してその静電容量値から水分量を検知する方法である。ここで水分量は水分量＝水体積／（Ｓ×ｄ）で表され、Ｓは電極１００ａ，１００ｂの面積、ｄは電極間距離であり、Ｓ×ｄは検知エリアの体積を示す。
そして水分量と静電容量Ｃｘは
Ｃｘ＝［ε’（水）×水分量＋ε’（他）×（１−水分量）］×ε０×Ｓ／ｄとなる。ここで水の比誘電率ε’（水）は８０，比誘電率ε’（他）は木材の場合には２、空気の場合には１であり、検知領域内の水分量によって静電容量Ｃｘが決定される。静電容量Ｃｘの値は電極１００ａ，１００ｂの大きさにも依存するが、乾燥状態で数ｐＦ、水分が多い状態で数１０ｐＦを示す。（例えば、工業計測技術体系編集委員会編：湿度・水分測定日刊工業新聞社刊１９６５参照）
図２３は水分量と静電容量Ｃｘとの関係を示す。
【０００９】
【発明が解決しようとする課題】
上記のような検知対象物に対して接触させて検知対象物中の水分量を検知できる静電容量式にあっても、次のような問題があった。
【００１０】
つまり図２４（ａ）（ｂ）に示すように構造物たる容器１０５の内壁の開口部１０１に絶縁構造物１０２を配設して、互いの電極面が対向するように平行配置した電極１００ａ，１００ｂでは電極１００ａ，１００ｂ間に検出対象物が埋まって、堆積物として残留してしまい、その結果容量検知回路１０３は電極１００ａ、１００ｂ間の堆積物の水分量を測定することになってしまい検知対象物の水分量を反映しなくなるという問題があった。そのためには堆積残留しないようにな清掃構造が必要になるが、清掃構造を持たせるためには、製作コストの上昇を招くという問題があった。尚容量検知回路１０３の検知出力を入力する出力部１０４は容量検知回路１０３が検知する静電容量値から水分量に相当する電気量、例えば電圧値を持つ電圧信号を出力する。
【００１１】
また容器１０５内に電極１００ａ，１００ｂが突出することになり、そのため容器１０５内の検知対象物の移動を阻害し、また電極１００ａ、１００ｂに荷重がかかったり、他の部分に堆積物が残留してしまうという問題があった。そのため電極１００ａ，１００ｂの構造に荷重に耐えるだけの強度を持たせることが必要になり、結果電極構造が大きくなったり、製作コストが上昇するという問題があった。
【００１２】
尚図２４（ｂ）中Ｃｘは検知対象物による静電容量を示す。
【００１３】
本発明は、上記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、一対の電極によって構成される電界領域を検知領域とするときに、検知領域中に含まれる水分量を、検知対象物の静止中及び移動中の何れにおいてもリアルタイムで誤差無く検知でき、しかも絶縁体の割れ、撓み、電極の剥離などを生じない静電容量式水分量センサを提供することにある。
【００１４】
【課題を解決するための手段】
請求項１の発明では、一対の電極によって構成された電界領域を検知領域とし、上記一対の電極中の少なくとも一方の電極が絶縁体を介して検知対象物に接する面を検知感度面とする電極部と、上記検知領域内に存在する水分量で決定される静電容量値を検知する容量検知回路及び該容量検知回路が検知した静電容量値から水分量に相当する電気量を持つ電気信号を出力する出力回路から少なくとも構成される水分量センサ回路部と、から成る静電容量式水分量センサにおいて、上記絶縁体を介して検知対象物に接する上記電極を上記検知感度面とは反対側の上記絶縁体の面に蒸着した金属蒸着膜により形成するとともに、該金属蒸着膜を蒸着して電極を形成する上記絶縁体の面にリブを一体に設けて成ることを特徴とする。
【００１７】
請求項２の発明では、請求項１の発明において、上記リブを一対の電極間で発生する電界方向と略平行で且つ略垂直方向となるように上記絶縁体面に垂立形成して成ることを特徴とする。
【００１８】
請求項３の発明では、請求項１又は２の発明において、上記水分量センサ回路部を実装した回路基板と、上記金属蒸着膜からなる電極とを半田付けによりリード線で接続するとともに、当該電極に対するリード線の半田付けによる接続部位を、金属蒸着膜形成位置に存在するリブとの境界位置にある当該電極の端部としたことを特徴とする。
【００１９】
請求項４の発明では、請求項１又は２の発明において、上記水分量センサ回路部を実装した回路基板と、上記金属蒸着膜からなる電極とを半田付けによりリード線で接続するとともに、当該電極に対するリード線の半田付けによる接続部位を、上記電極の形成位置内に設けた凹部内としたことを特徴とする請する。
【００２０】
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、上記絶縁体が、上記水分量センサ回路部を実装した回路基板を収納する樹脂成型品である水分量センサ筐体の一部であって、該水分量センサ筐体内面には上記水分量センサ回路部の０Ｖ電位点と電気的に接続した金属蒸着膜による電波シールド部を形成して成ることを特徴とする。
【００２１】
請求項６の発明では、請求項１乃至５の何れかの発明において、上記絶縁体が、上記水分量センサ回路部を実装した回路基板を収納する樹脂成型品である水分量センサ筐体の一部であって、該水分量センサ筐体内には、金属蒸着膜による導電部を表面に形成して該導電部を介して上記電極若しくはシールド部位と、上記回路基板の回路とを電気的に接続する構造体を設けて成ることを特徴とする。
【００２２】
請求項７の発明では、請求項６の発明において、上記構造体は水分量センサ筐体と一体に形成されたもので、先端面にねじ螺入用孔を開口し、上記回路基板を上記先端面に載置支持するとともに、回路基板の側に設けた挿通孔を介してねじ螺入用孔に螺入される固定ねじの締結により回路基板を支持固定し、且つ上記固定ねじの締結により回路基板側の載置面に設けた導電パターンと構造体の先端面に位置する上記導電部とを圧接して成ることを特徴とする。
【００２３】
請求項８の発明では、請求項６の発明において、上記構造体は水分量センサ筐体と一体に形成されたもので、先端部を上記回路基板に形成した挿入孔に回路基板裏面側から挿入して回路基板の表面側に露出させた上記先端部表面の上記導電部と、回路基板表面側の導電パターンとを電気的に接続して成ることを特徴とする。
【００２４】
請求項９の発明では、請求項６の発明において、上記構造体の先端部に、上記回路基板側からの被接続コネクタを接続するコネクタ部を設けるとともに、被接続コネクタに電気的に接続するコネクタ部の接続導電体と、上記構造体の上記導電部とを電気的に接続して成ることを特徴とする。
【００２６】
【発明の実施の形態】
以下本発明を実施形態により説明する。
【００２７】
（実施形態１）
図１は本実施形態の静電容量式水分量センサ３０の全体の斜視図を示しており、底浅で底面の外形状が略正方形で、内底部の中央の円形状凹部１０に電極部を配設した合成樹脂製の絶縁体からなる水分量センサ筐体１と、この水分量センサ筐体１内に配置されるプリント基板からなる回路基板２と、この回路基板２の回路部品実装部を覆うように回路基板１上に配置されるシールドボックス３と、水分量センサ筐体１の開口部にパッキン４を介して被着される金属板のような導電体からなる蓋２９とで構成される。
【００２８】
水分量センサ筐体１は図２（ａ）〜（ｄ）に示すように、ポリカーボネート、ポリプロピレン、ポリフェニレンサルファイド等の成形材料により成形されたもので、電極部を配設する凹部１０の底部の厚みを５ｍｍ乃至０．１ｍｍ程度に形成している。
【００２９】
凹部１０は図２（ａ）、（ｃ）、（ｄ）に示すように底壁を外方向に膨出させることで形成され、底面上には同心状に３つの円環状のリブ２６１〜２６４を一体形成するとともに、中心のリブ２６１の外側周壁面から放射状に複数のリブ２６を凹部１０の内周面に達するまで形成してある。
【００３０】
図３（ａ）、（ｃ）、（ｄ）で示す例は図２における，リブ２６３を無くした例を示す。
【００３１】
中心のリブ２６１で囲繞される凹所Ａが電極５ａを構成する金属蒸着膜を形成する場所となり、外側のリブ２６３（或いは２６２）と、２６４とリブ２６と囲まれた凹所Ｂが環状の電極５ｂを構成する金属蒸着膜を形成する場所となり、これら凹所Ａ，Ｂが電極形成場所の目印ともなる。
【００３２】
電極５ａ，５ｂは銅、アルミニウム等の金属蒸着膜を凹所Ａの底面と、部位Ｂの底面に形成して、それらの金属蒸着膜により構成されたものである。またこれらの電極５ａ、５ｂの表面には腐食防止のために半田メッキ或いは金メッキを施して保護膜とする。
【００３３】
図４（ａ）〜（ｃ）は図２に示す水分量センサ筐体１における電極形成後を示しており、同図（ａ）において網線で示す部分が電極５ａ又は５ｂを示す。
【００３４】
ここで電極形成方法としては、上記凹み部Ａ，Ｂに金属蒸着膜を形成するように蒸着をコントロールするか、周辺を含めて金属蒸着膜を形成し、この形成後電極５ａ、５ｂを構成する部位を除くように選択的に剥離して形成する方法の何れかがあるが、適宜何れかの方法を採用すればよい。図５は、図３に示す水分量センサ筐体１における電極形成後を示しており、この場合リブ２６２，２６４の間に一旦金属蒸着膜を形成した後、図示するように電極５ｂの形状となるように不要な金属蒸着膜を選択除去した場合を示す。
【００３５】
尚図４或いは図５で示す電極５ｂはリブ２６によって分断される形で形成されるためこれら分断部を電気的に適宜な方法で接続して、一つの環状の電極５ｂを構成する。
【００３６】
図６はリブ２６を含めて金属蒸着膜を形成して、環状の電極５ｂを形成した例を示しており、この場合にはリブ２６により電気的に分断されることが無いため、分断部を電気的に接続する必要がない。またリブ２６を蒸着しなようにするための選択マスクを必要とせず、蒸着処理が簡単となる。
【００３７】
ところで図６のようにリブ２６表面にも金属蒸着膜を形成して電極５ｂを構成する場合には、該部位も検知領域内で電界領域を構成するため、後述する容量検知回路６で検知される静電容量値に影響を及ぼす恐れがある。つまりこの影響はリブパターンが検知領域の電界強度分布に密接な関係があり、リブパターンが電界方向と無関係に構築されると電界分布を不均一に乱すことになる。
【００３８】
そこで本実施形態における中心の電極５ａと、電極５ｂとの電界方向は図７（ａ）（ｂ）に示すように放射状で且つ垂直面を通ることから、リブ２６を電界方向に略平行となるように中心から放射状に延長形成し、かつ凹部１０の底面に対して垂直に垂立させて、対称性のある規則性を持たせ、検知領域内の電界分布が対称性をもって均一性な分布となるようにしてある。つまり検知対象物に異物が混入されて検知する水分量に誤差が含まれる場合、電界密度にばらつきがあるような不均一な電界分布では、電界密度の高いところに水分量が多い異物が混入すると、上記誤差が大きくなる。これに対して電界分布が均一であると、水分量の多い異物が混入されても、検知誤差を低くすることができる。
【００３９】
またリブ２６，２６１〜２６４を形成することで水分量センサ筐体１の強度を高め、しかも電極５ａ、５ｂを金属蒸着膜により構成するため、樹脂成形部位の割れや、電極５ａ、５Ｂの剥離が生じ難く、また金属蒸着膜により電極５ａ、５ｂを形成しているため電極５ａ，５ｂと検知感度面２３までの距離、つまりその間に介在する樹脂成形部位の厚みの管理が容易となる。
【００４０】
さて回路基板２は凹部１０の周辺の水分量センサ筐体１の底面に４隅付近に一体立設してある柱体１２上に載置した状態で図８に示すように柱体１２の孔１２ａに固定ねじ１３を螺入締結することで固定される。この回路基板２上には図８に示すように水分量センサ回路部たる水分量センサ回路ブロック９を構成する電子部品が実装され、更に電子部品を覆うように板金加工によって形成された金属製のシールドボックス３が載置固定されている。回路基板２上の回路と電極５ａ、５ｂとはリード線４０を介して接続されている。また蓋２９と回路基板２上の水分量センサ回路ブロック９の動作基準点αとはリード線４０’により接続されている。
【００４１】
水分量センサ回路ブロック９は、図９に示すように電極部を構成する一対の電極５ａ、５ｂ間の電界領域により構成される検知領域の静電容量値Ｃｘを検知する容量検知回路６と、容量検知回路６の検知容量値に応じた電気量、例えば電圧信号を出力する出力回路７と、これら容量検知回路６及び出力回路７に動作電源を供給する電源回路８と、これら回路６乃至８のグランド、つまり容量検知回路６の動作基準点αと、大地βとの間に接続して容量検知回路６の動作基準点αと大地βとの間のインピーダンスを決定するコンデンサＣ_Ｅとから構成され、回路基板１上に被着されるシールドボックス３によりシールドされ、また上記動作基準点αがシールドボックス３に接続される。電源回路８は例えば３端子レギュレータＩＣなどにより構成される。
【００４２】
電源回路８及び出力回路７は、一端が回路基板１側回路に接続され、他端側を図８に示すようにシールドボックス３、蓋２９を介して外部に導出したケーブル２０の先端に設けたコネクタ２１を用いて外部の操作盤１４に接続されるようになっており、ケーブル２０を介して操作盤１４から電源回路８の電源が供給され、また出力回路７の出力信号が操作盤１４へ送出される。
【００４３】
尚シールドボックス３は水分量センサ回路ブロック９を電磁遮蔽するものである。また凹部１０にはシリコンゴムなどの絶縁物１１が充填され、水分量センサ筐体１内で結露が発生しても、その水で電極５ａ，５ｂが短絡するのを防止している。
【００４４】
ところで本実施形態では上記リード線４０と電極５ｂとの接続を、図１０（ａ）（ｂ）に示すように電極５ｂの外周端部とリブ２６４との境界部においてリード線４０の芯線４０ａを半田付けして行うようになっている。この場合リブ２６４が半田１５の流れを防ぐ壁となり、信頼性を向上させている。
【００４５】
尚図１１（ａ）（ｂ）に示すように電極５ｂを形成している凹所Ｂの底面に一端がリブ２６４に連なり、且つ平行する部位を持つ壁１６を立設し、この壁２４とリブ２６４で形成される凹部１７をリード線４０と電極５ｂとの半田付け部位として、この凹部１７を構成する壁１６及びリブ２６４で半田１５の流れを防ぐ壁を構成しても良い。
【００４６】
而して上述のように構成した本実施形態の水分量センサ３０を検知対象物Ｘを入れている容器３１の壁面に取り付けるに当たっては、図８に示すように容器３１の壁面に開口した窓孔３２に水分量センサ筐体１の凹部１０に対応する膨出部２２を容器３１の外側から嵌合する。ここで膨出部２２の突出量と容器３１の壁の厚さとを略同じ寸法に設定しており、窓孔３２に膨出部２２を嵌め込む際に、膨出部２２の周辺の水分量センサ筐体１の外底面１ａと容器３１の外壁面とを直接当てて位置決めを行うことで、容器３１内に臨む膨出部２２の外面、つまり検知感度面２３が容器３１の内壁面と同一面（面一）となるように配置される。そして蓋２９、パッキン４、水分量センサ筐体１の４角に設けた孔２８ａ，２８ｂ，２８ｃを貫挿させた取り付けボルト（図示せず）により容器３１に水分量センサ３０を固定する。
【００４７】
本実施形態では上述のように水分量センサ３０を容器３１に取り付けることで、電極５ａ、５ｂが直接検知対象物Ｘに触れることがなく、また検知感度面２３が容器３１内に突出することもないため、電極５ａ、５Ｂ間に検知対象物Ｘが埋まったり、移動を阻害することがなく、例えば検知対象物Ｘが発酵工程の発酵物・米・穀類・茶葉・タバコの葉・生ゴミ・木材・土壌・コンクリート細骨材など何れにおいても、一対の電極５ａ、５ｂによって構成される電界領域を検知領域とするときに、その検知領域中に含まれる水分量を、検知対象物Ｘが静止中であっても、あるいは攪拌、搬送などの移動中においてもリアルタイムで誤差無く、検知することができる。
【００４８】
また電界分布に均一性を持たせるように構成しているため、検知対象物Ｘに異物が混入していても、誤差を低減することができる。
【００４９】
尚図１２（ａ）に示すように電極５ａを正方形で、周囲を囲む電極５ｂを４周枠状に形成して、電極５ａの一辺の長さｄ０と、電極５ｂの幅ｄ１とを同じ寸法とし、両者の並行する辺間の距離ｄ２を４周とも同じ寸法としても良い。この場合も浮遊容量に対する影響を低減することができる。
【００５０】
また中央の電極５ａの形状を正方形や円形ではなく、図１２（ｂ）に示すように長方形、或いは同図（ｃ）に示すように長円形、更には図１２（ｄ）に示すように楕円形とし、夫々に対応した環状の電極５ｂを組み合わせても良い。
【００５１】
（実施形態２）
ところで上記実施形態１は検知対象物Ｘが入っている容器３１の外壁面及び内壁面が共に平坦な面に対応するものであったが、少なくとも内壁面が曲面となっているような場合には、検知感度面２３を容器３１の内壁面と面一にはできない。
【００５２】
そこで本実施形態では図１３乃至図１５に示すように膨出部２２の外面、つまり検知感度面２３を容器３１の円弧状の内壁面と面一となるように曲面としてある。この場合膨出部２２の壁、つまり凹部１０の底壁の厚さを略等しく、凹部１０の底部に金属蒸着膜で形成する電極５ａ、５ｂと検知感度面２３までの距離を等しくしてある。
【００５３】
尚その他の構成は実施形態１と同じ構成であるので、図１３乃至図１５において、実施形態１の構成要素と同じ構成要素には同じ符号を付し説明は省略する。
【００５４】
尚図１３、図１４ではリブ２６、２６１〜２６４の図示を省略してある。
【００５５】
（実施形態３）
上記実施形態１，２は共に水分量センサ回路ブロック９をシールドボックス３で覆っていた。つまり、シールドボックス３により水分量センサ回路ブロック９で用いる周波数帯域（数１０ＭＨｚ〜数百ＭＨｚ）に合致するＦＭ放送やアマチュア無線周波数が到来しても遮蔽でき、誤動作要因を排除し、また逆に内部から輻射電波が外部に放射されるのを防止して、外部機器の誤動作を誘発する恐れを無くすようにしている。
【００５６】
しかし、シールドボックス３を金属部品にて作成する構成では、部品点数が多くなって部品コストが高くなる上に、組み立てコストも高くなる。
【００５７】
そこで本実施形態では電極５ａ、５ｂと同様に、金属蒸着膜からなるシールド部を構成し、部品点数の削減と、コスト削減を図った。
【００５８】
すなわち、図１６（ａ）（ｂ）に示すように水分量センサ筐体１の周壁の内面及び電極５ｂの外側に位置する凹部１０の底面、内周面、そして凹部１０の周辺の水分量センサ筐体１の底面に、電極５ａ、５ｂと同様に金属蒸着膜（網線で示す）を形成して、この金属蒸着蒸着膜によりシールド部２７を構成する。
【００５９】
従って、水分量センサ筐体１の開口部に金属の蓋２９を被着することで、蓋２７及びシールド部２７によって水分量センサ筐体１の内部をシールドすることができ、そのため到来する電波の内部への侵入防止と、内部の水分量センサ回路ブロック９から出る電波の外部への漏洩を防止することができる。
【００６０】
ここで蓋２９と回路基板２上の水分量センサ回路ブロック９の動作基準点αとは実施形態１と同様にリード線４０’により接続する（図８．図９参照）が、シールド部２７の金属蒸着膜と回路基板１上の水分量センサ回路ブロック９の動作基準点αとの接続は本実施形態では次のように行う。
【００６１】
つまり水分量センサ筐体１の底面に構造体として一体突設してある４本の柱体１２の内の１本の表面にも図１７（ａ）に示すようにシールド部２７の金属蒸着膜と連続している金属蒸着膜を導電部２７ａとして形成し、柱体１２の上に載置され、固定ねじ１３により固定される回路基板１の回路に金属蒸着膜よりなる導電部２７ａを通じて接続するようになっている。
【００６２】
このため回路基板１の裏面側には、図１７（ｃ）に示すように上記金属蒸着膜２７ａを形成した柱体１２のねじ螺入用の孔１２ａに対応するねじ挿通孔１９の開口周辺に導電パターン１８を形成し、また図１７（ｂ）に示すように回路基板１の表面側には水分量センサ回路ブロック９の動作基準点αに一端が接続された導電パターン３３の他端をねじ挿通孔１９の開口縁まで延長形成し、固定ねじ１５を回路基板１の表面側からねじ挿通孔１９に挿入して柱体１２の孔１２ａに螺入締結したときに、回路基板１側の載置面に設けた導電パターン１８が柱体１２の先端面の金属蒸着膜からなる導電部２７ａに圧接し、また固定ねじ１３の頭部が表面側の導電パターン３３に圧接し、動作基準点α、導電パターン３３、固定ねじ１３、導電パターン１８、柱体１２の金属蒸着膜からなる導電部２７ａ、シールド部２７の経路で、シールド部２７が動作基準点αを電気的に接続されるのである。
【００６３】
尚図１８は本実施形態を容器３１に取り付けた状態の概略構成の断面図を示している。そのの構成は実施形態１，２と同じであるので、ここでは特に図示しない。
【００６４】
（実施形態４）
上記実施形態３では、固定ねじ１３をシールド部２７と、回路基板１上の水分量センサ回路ブロック９の動作基準点αとの電気的接続を、金属蒸着膜２７ａを形成した柱体１２と、導電パターン１８，３３と、固定ねじ１３とを利用して行っているが、本実施形態では、図１９（ａ）に示すように高さ寸法を回路基板１の厚み分だけ他の柱体１２より高くした柱体１２’の表面に金属蒸着膜からなる導電部２７ａを形成するとともに、柱体１２’の先端部を貫挿させる挿入孔３４を図１９（ｃ）に示すように上記回路基板１に形成し、且つ図１９（ｂ）に示すように回路基板１の表面側において水分量センサ回路ブロック９の動作基準点αに一端が接続された導電パターン３３を挿入孔３４の開口部近くまで延設し、固定ねじ１３による回路基板１の固定を、導電部２７ａを表面に形成している柱体１２’以外の柱体１２に対して行うようになっている。
【００６５】
そして柱体１２’の上端面を挿入孔３４を介して表面側に臨ませて上端面の金属蒸着膜２７ａと、導電パターン３３とをリード線３５で電気的に接続することで、水分量センサ回路ブロック９の動作基準点α（図９参照）に、導電パターン３３と、リード線３５と、柱体１２’の金属蒸着膜からなる導電部２７ａとを介してシールド部２７を電気的に接続するのである。
【００６６】
尚図２０は本実施形態を容器３１に取り付けた状態の概略構成の断面図を示している。そのの構成は実施形態１，２と同じであるので、ここでは特に図示しない。
【００６７】
（実施形態５）
上記実施形態３，４は回路基板１を支持固定するために設けた柱体１２’を利用してシールド部２７と、回路基板１上の水分量センサ回路ブロック９の動作基準点αを接続する構成であったが、本実施形態では図２１に示すように回路基板１側の水分量センサ回路ブロック９の例えば容量検知回路６の入力端にリード線３８を介して接続している被接続用の雌型コネクタＣＮ１に対応する雄型のコネクタ部ＣＮ２を先端部に一体に設けた構造体３６を、水分量センサ筐体１の底面に一体的に設けるとともに、雌型コネクタＣＮ１に電気的に接続するコネクタ部ＣＮ２の接続導電体たるピン３７と、例えば電極５ａ、５ｂとを電気的に接続するために水分量センサ筐体１の底面上及び上記構造体３６の表面に亘るように金属蒸着膜からなる導電部２７ａ’を形成してある。
【００６８】
而して本実施形態では、回路基板１上の水分量センサ回路ブロック９の容量検知回路６と電極５ａ、５ｂとの接続は雌型コネクタＣＮ１を構造体３６の雄型コネクタ部ＣＮ２に接続することにより行える。尚３９ａは雄型コネクタ部ＣＮ２側に設けた係止片で、この係止片３９ａには雌型コネクタＣＮ１の弾性係止爪片３９ｂが係脱自在に係止され、コネクタＣＮ１の抜け止めを図っている。
【００６９】
尚本実施形態では電極の接続に用いたが、シールド部等の接続に用いても良い。
【００７０】
【発明の効果】
請求項１の発明は、一対の電極によって構成された電界領域を検知領域とし、上記一対の電極中の少なくとも一方の電極が絶縁体を介して検知対象物に接する面を検知感度面とする電極部と、上記検知領域内に存在する水分量で決定される静電容量値を検知する容量検知回路及び該容量検知回路が検知した静電容量値から水分量に相当する電気量を持つ電気信号を出力する出力回路から少なくとも構成される水分量センサ回路部と、から成る静電容量式水分量センサにおいて、上記絶縁体を介して検知対象物に接する上記電極を上記検知感度面とは反対側の上記絶縁体の面に蒸着した金属蒸着膜により形成したので、検知対象物中に含まれる水分量を、検知対象物が静止中は勿論のこと移動中であってもリアルタイムに検知できるものであり、電極部を構成する一対の電極の少なくとも一方が直接検知対象物に触れないため、当該電極の清掃が容易であり、また当該電極が水分中の金属イオンで溶けるという現象も防げ、また絶縁体により保護されているため、検知感度面の摩耗も均一となって、感度検知面に検知対象物の流れを阻害するよう凹凸ができにくくなり、その凹凸による検知対象物の堆積や、流れの阻害を生じる恐れがなく、また他方の電極との間に検知対象物が埋まる恐れも少ないものであって、絶縁体の検知感度面に検知対象物による荷重がかかっても、電極を接着している場合の剥離や、電極をインサートしている場合のような絶縁体の割れを招くことがなく、また曲面となった検知感度面に合わせて、電極面も曲面とする必要がある場合にも容易に電極形成ができ、電極と検知感度面までの距離の管理も容易に行えるという効果がある。しかも、上記金属蒸着膜を蒸着して電極を形成する上記絶縁体の面にリブを一体に設けてあるので、絶縁体の強度を強くすることができ、絶縁体の撓み、割れを防止することができるという効果がある。
【００７３】
請求項２の発明では、請求項１の発明において、上記リブを一対の電極間で発生する電界方向と略平行で且つ略垂直方向となるように上記絶縁体面に垂立形成してあるので、リブの存在が検知領域内の電界分布を不均一にすることがない。
【００７４】
請求項３の発明では、請求項１又は２の発明において、上記水分量センサ回路部を実装した回路基板と、上記金属蒸着膜からなる電極とを半田付けによりリード線で接続するとともに、当該電極に対するリード線の半田付けによる接続部位を、金属蒸着膜形成位置に存在するリブとの境界位置にある当該電極の端部としたので、リブが半田の流れを防ぐ壁となり、信頼性の向上が図れる。
【００７５】
請求項４の発明では、請求項１又は２の発明において、上記水分量センサ回路部を実装した回路基板と、上記金属蒸着膜からなる電極とを半田付けによりリード線で接続するとともに、当該電極に対するリード線の半田付けによる接続部位を、上記電極の形成位置内に設けた凹部内としたので、凹部の壁面が半田の流れを防ぐ壁となり、信頼性の向上が図れる。
【００７６】
請求項５の発明は、請求項１乃至４の何れかの発明において、上記絶縁体が、上記水分量センサ回路部を実装した回路基板を収納する樹脂成型品である水分量センサ筐体の一部であって、該水分量センサ筐体内面には上記水分量センサ回路部の０Ｖ電位点と電気的に接続した金属蒸着膜による電波シールド部を形成してあるので、電波シールド部により外部からの電波を遮蔽できて、外部からの電波による誤動作を防ぎ、また内部からの輻射電波の漏洩を防いで、外部機器への影響を無くすことができ、また金属部品にてシールドケースを製作する場合に比べて部品数も増加せず、部品コストも安価であり、しかも組み込む工程も必要でないから組立コストも安価となる。
【００７７】
請求項６の発明は、請求項１乃至５の何れかの発明において、上記絶縁体が、上記水分量センサ回路部を実装した回路基板を収納する樹脂成型品である水分量センサ筐体の一部であって、該水分量センサ筐体内には、金属蒸着膜による導電部を表面に形成して該導電部を介して上記電極若しくはシールド部位と、上記回路基板の回路とを電気的に接続する構造体を設けてあるので、シールド部位や電極と回路基板側との接続をリード線を用いて行う場合に比べて水分量センサ筐体内の配線が整然と行える。
【００７８】
請求項７の発明では、請求項６の発明において、上記構造体は水分量センサ筐体と一体に形成されたもので、先端面にねじ螺入用孔を開口し、上記回路基板を上記先端面に載置支持するとともに、回路基板の側に設けた挿通孔を介してねじ螺入用孔に螺入される固定ねじの締結により回路基板を支持固定し、且つ上記固定ねじの締結により回路基板側の載置面に設けた導電パターンと構造体の先端面に位置する上記導電部とを圧接してあるので、回路基板の配設固定と同時に回路基板側と、シールド部位や電極と回路基板側との電気的接続が行える。
【００７９】
請求項８の発明では、請求項６の発明において、上記構造体は水分量センサ筐体と一体に形成されたもので、先端部を上記回路基板に形成した挿入孔に回路基板裏面側から挿入して回路基板の表面側に露出させた上記先端部表面の上記導電部と、回路基板表面側の導電パターンとを電気的に接続してあるので、シールド部位や電極と回路基板側との電気的接続を回路基板表面側で行えるので、回路基板の下方の空間においてリード線を配線する場合に比べて整然と配線が行える。
【００８０】
請求項９の発明では、請求項６の発明において、上記構造体の先端部に、上記回路基板側からの被接続コネクタを接続するコネクタ部を設けるとともに、被接続コネクタに電気的に接続するコネクタ部の接続導電体と、上記構造体の上記導電部とを電気的に接続してあるので、シールド部位や電極と回路基板側との電気的接続が簡単且つ迅速に行える。
【図面の簡単な説明】
【図１】実施形態１の分解斜視図である。
【図２】（ａ）は同上の水分量センサ筐体の一例の平面図である。
（ｂ）は同上の水分量センサ筐体の一例の側面図である。
（ｃ）は同上の水分量センサ筐体の一例の側断面図である。
（ｄ）は同上の（ａ）図のイ−イ断面図である。
【図３】（ａ）は同上の水分量センサ筐体の別の例の平面図である。
（ｂ）は同上の水分量センサ筐体の別の例の側面図である。
（ｃ）は同上の水分量センサ筐体の別の例の側断面図である。
（ｄ）は同上の（ａ）図のイ−イ断面図である。
【図４】（ａ）は同上の水分量センサ筐体の電極形成後の一例の平面図である。
（ｂ）は同上の水分量センサ筐体の電極形成後の一例の側面図である。
（ｃ）は同上の水分量センサ筐体の電極形成後の一例の側断面図である。
（ｄ）は同上の（ａ）図のイ−イ断面図である。
【図５】同上の水分量センサ筐体の電極形成後の別の例の平面図である。
【図６】同上の水分量センサ筐体の電極形成後の別の例の平面図である。
【図７】同上に水分量センサ筐体に形成するリブの方向の説明図である。
【図８】同上を容器に取り付けた状態の断面図である。
【図９】同上の水分量センサ回路ブロックの回路構成図である。
【図１０】（ａ）は同上の電極とリード線との接続部位の一部省略せる拡大上面図である。
（ｂ）は同上の電極とリード線との接続部位の一部省略せる拡大断面図である。
【図１１】（ａ）は同上の電極とリード線との接続部位の別の例の一部省略せる拡大上面図である。
（ｂ）は同上の電極とリード線との接続部位の別の例の一部省略せる拡大断面
【図１２】同上の電極形状の他の例の説明図である。
【図１３】実施形態２の断面図である。
【図１４】（ａ）は同上の水分量センサ筐体の概略平面図である。
（ｂ）は同上の水分量センサ筐体の概略側断面図である。
（ｃ）は同上の水分量センサ筐体の充填物の充填状態を示す概略側断面図である。
【図１５】（ａ）は同上の水分量センサ筐体の平面図である。
（ｂ）は同上の水分量センサ筐体の側面図である。
（ｃ）は同上の水分量センサ筐体の側面図である。
【図１６】（ａ）は実施形態３の水分量センサ筐体の平面図である。
（ｂ）は同上の水分量センサ筐体の側面図である。
（ｃ）は同上の水分量センサ筐体の側断面図である。
【図１７】（ａ）は同上の水分量センサ筐体の概略平面図である。
（ｂ）は同上の水分量センサ筐体の回路基板配設状態の概略平面図である。
（ｃ）は同上の回路基板の下面図である。
【図１８】同上を容器に取り付けた状態の概略断面図である。
【図１９】（ａ）は実施形態４の水分量センサ筐体の概略平面図である。
（ｂ）は同上の水分量センサ筐体の回路基板配設状態の概略平面図である。
（ｃ）は同上の回路基板の下面図である。
【図２０】同上を容器に取り付けた状態の概略断面図である。
【図２１】実施形態５の要部の一部省略せる分解斜視図である。
【図２２】静電容量式水分量検知センサの原理説明図である。
【図２３】検知される静電容量値と水分量の関係説明図である。
【図２４】（ａ）は従来例の電極部の一部省略せる平面図である。
（ｂ）は同上の回路結線図である。
【符号の説明】
１水分量センサ筐体
２回路基板
３シールドボックス
４パッキン
５ａ，５ｂ電極
１０凹部
２９蓋[0001]
BACKGROUND OF THE INVENTION
The present invention is a capacitance type moisture content sensor that detects the amount of moisture and the presence or absence of moisture.ToIt is related.
[0002]
[Prior art]
Conventionally, methods for measuring the amount of water are generally classified into an infrared absorption type, a microwave type, an electric resistance type, a capacitance type, and a weight type.
[0003]
However, in a moisture sensor that uses transmitted infrared light in the above infrared absorption type, the detection target must be made of a material that transmits infrared light. In this case, it is suitable for a thin paper or the like up to about several mm, but is not suitable for a material that does not transmit infrared light. Furthermore, in the moisture amount sensor using reflected infrared light, the reflection condition is greatly influenced by the uneven state and color of the surface of the detection target. That is, there is a problem in that it is not possible to determine whether the amount of light reduction with respect to the amount of irradiation light is due to moisture absorption or reflection conditions, and it is not possible to accurately detect the amount of moisture.
[0004]
In addition, the microwave method measures the amount of propagation energy loss caused by the complex dielectric constant, which causes a problem that the apparatus becomes complicated and the manufacturing cost is high.
[0005]
In addition, the electrical resistance formula is a method of measuring resistance components using the electrical conductivity of water, but in reality impurities such as salt (NaCl) contained in moisture were formed by electrolysis. The ionic conductivity is orders of magnitude greater, so the value that can be measured by resistance is actually the concentration of impurities dissolved in moisture.
[0006]
Furthermore, the gravimetric method is not suitable for online measurement because of its measurement principle.
[0007]
On the other hand, the capacitance type causes an error if a dielectric constant equivalent to that of water is present, but the above-mentioned application (fermentation process / cereal grains such as rice, etc.) that does not contain an organic solvent substance having a relative dielectric constant of 20 to 50・ When detecting the amount of water contained in each substance on-line or off-line with tea leaves, tobacco leaves, garbage, wood, soil, concrete fine aggregates, etc. while each is stationary or moving In addition, since there is no substance with a relative permittivity equivalent to that of water among substances present in rain detection, water level monitoring during bath hot water detection, human body seating detection, etc., it is possible to detect the amount of moisture with little error. There is a feature that the amount of water in the detection target can be detected by contacting the target.
[0008]
The principle of the capacitance type is that the property of water being a substance (dielectric) that is polarized is used to measure the capacitance value between a pair of electrodes 100a and 100b as shown in FIG. This is a method of detecting the moisture content from the capacitance value. Here, the amount of water is expressed by the amount of water = water volume / (S × d), S is the area of the electrodes 100a and 100b, d is the distance between the electrodes, and S × d is the volume of the detection area.
And the water content and capacitance Cx are
Cx = [ε ′ (water) × water content + ε ′ (other) × (1−water content)] × ε0 × S / d. Here, the relative dielectric constant ε ′ (water) of water is 80, the relative dielectric constant ε ′ (others) is 2 for wood, and 1 for air, and the capacitance depends on the amount of moisture in the detection region. Cx is determined. Although the value of the capacitance Cx depends on the size of the electrodes 100a and 100b, it shows several pF in a dry state and several tens pF in a state with a lot of moisture. (See, for example, Industrial Measurement Technology System Editorial Committee: Humidity and Moisture Measurement published by Nikkan Kogyo Shimbun 1965)
FIG. 23 shows the relationship between the moisture content and the capacitance Cx.
[0009]
[Problems to be solved by the invention]
Even in the capacitance type that can detect the amount of water in the detection object by contacting the detection object as described above, there are the following problems.
[0010]
That is, as shown in FIGS. 24A and 24B, the insulating structure 102 is disposed in the opening 101 on the inner wall of the container 105 as a structure, and the electrodes 100a are arranged in parallel so that the electrode surfaces face each other. In 100b, an object to be detected is buried between the electrodes 100a and 100b and remains as a deposit. As a result, the capacitance detection circuit 103 measures the moisture content of the deposit between the electrodes 100a and 100b. There was a problem of not reflecting the moisture content of the object. For this purpose, a cleaning structure is required so as not to remain deposited. However, in order to provide the cleaning structure, there has been a problem that the manufacturing cost is increased. The output unit 104 that inputs the detection output of the capacitance detection circuit 103 outputs a voltage signal having an electric amount corresponding to the amount of moisture, for example, a voltage value, from the capacitance value detected by the capacitance detection circuit 103.
[0011]
In addition, the electrodes 100a and 100b protrude into the container 105, so that the movement of the detection target in the container 105 is hindered, a load is applied to the electrodes 100a and 100b, and deposits remain in other parts. There was a problem that. Therefore, it is necessary to give the structure of the electrodes 100a and 100b strong enough to withstand the load. As a result, there are problems that the electrode structure becomes large and the manufacturing cost increases.
[0012]
In FIG. 24B, Cx represents the capacitance due to the detection target.
[0013]
The present invention has been made in view of the above-described problems. The object of the present invention is to determine the amount of moisture contained in the detection region when the detection region is an electric field region formed by a pair of electrodes. In addition, the object can be detected in real time with no error when the object is stationary or moving, and the insulator breaks., DeflectionCapacitive moisture sensor that does not cause electrode peelingSaIt is to provide.
[0014]
[Means for Solving the Problems]
In the invention of claim 1, an electric field region constituted by a pair of electrodes is a detection region, and an electrode having at least one of the pair of electrodes in contact with a detection object via an insulator is a detection sensitivity surface. And a capacitance detection circuit for detecting a capacitance value determined by the amount of moisture present in the detection region, and an electric signal having an amount of electricity corresponding to the amount of moisture from the capacitance value detected by the capacitance detection circuit A capacitance sensor circuit unit comprising at least a moisture sensor circuit unit configured to output an output circuit, wherein the electrode in contact with the object to be detected via the insulator is opposite to the detection sensitivity surface. Formed by metal deposition film deposited on the insulator surfaceIn addition, a rib is integrally provided on the surface of the insulator that forms the electrode by depositing the metal deposition film.It is characterized by comprising.
[0017]
Claim2In the invention of claim1In the present invention, the rib is vertically formed on the insulator surface so as to be substantially parallel to and substantially perpendicular to the direction of the electric field generated between the pair of electrodes.
[0018]
Claim3In the invention of claim1 or 2In this invention, the circuit board on which the moisture sensor circuit unit is mounted and the electrode made of the metal vapor deposition film are connected by a lead wire by soldering, and the connection part by soldering of the lead wire to the electrode is connected to a metal. It is characterized in that it is the end portion of the electrode at the boundary position with the rib existing at the deposited film forming position.
[0019]
Claim4In the invention of claim1 or 2In the invention, the circuit board on which the moisture sensor circuit unit is mounted and the electrode made of the metal vapor deposition film are connected by a lead wire by soldering, and the connection part by soldering the lead wire to the electrode is connected to the electrode The feature is that it is in a recess provided in the electrode formation position.
[0020]
Claim5In the present invention, claims 1 to4In any one of the inventions, the insulator is a part of a moisture sensor housing that is a resin molded product that houses a circuit board on which the moisture sensor circuit unit is mounted, and the inner surface of the moisture sensor housing Is characterized in that a radio wave shield portion is formed by a metal vapor deposition film electrically connected to the 0 V potential point of the moisture amount sensor circuit portion.
[0021]
Claim6In the present invention, claims 1 to5In any one of the inventions, the insulator is a part of a moisture sensor housing that is a resin molded product that houses a circuit board on which the moisture sensor circuit unit is mounted. Is characterized in that a conductive part is formed on the surface by a metal vapor deposition film and a structure for electrically connecting the electrode or shield part and the circuit of the circuit board through the conductive part is provided. .
[0022]
Claim7In the invention of claim6In this invention, the structure is formed integrally with the moisture sensor housing, and has a screw screw hole formed in the tip surface, and the circuit board is placed and supported on the tip surface. The circuit board is supported and fixed by fastening a fixing screw screwed into the screw screw hole through the insertion hole provided on the side, and the conductive plate provided on the mounting surface on the circuit board side by fastening the fixing screw. The pattern is formed by press-contacting the conductive portion located on the tip surface of the structure.
[0023]
Claim8In the invention of claim6In this invention, the structure is formed integrally with the moisture sensor housing, and the tip is inserted into the insertion hole formed in the circuit board from the back side of the circuit board and exposed to the front side of the circuit board. The conductive portion on the surface of the tip portion is electrically connected to the conductive pattern on the surface side of the circuit board.
[0024]
Claim9In the invention of claim6In the invention, a connector portion for connecting a connector to be connected from the circuit board side is provided at a tip portion of the structure body, a connection conductor of the connector portion to be electrically connected to the connector to be connected, and the structure body It is characterized in that it is electrically connected to the conductive part.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0027]
(Embodiment 1)
FIG. 1 shows a perspective view of the entire capacitance type moisture sensor 30 of the present embodiment. The outer shape of the bottom surface is substantially square and the electrode portion is provided in the circular recess 10 at the center of the inner bottom portion. A moisture sensor housing 1 made of an insulating material made of synthetic resin, a circuit board 2 made of a printed circuit board disposed in the moisture sensor housing 1, and a circuit component mounting portion of the circuit board 2 The shield box 3 is disposed on the circuit board 1 so as to cover the lid, and the lid 29 is made of a conductor such as a metal plate attached to the opening of the moisture sensor housing 1 via the packing 4. The
[0028]
As shown in FIGS. 2A to 2D, the moisture sensor housing 1 is formed of a molding material such as polycarbonate, polypropylene, polyphenylene sulfide, etc., and the thickness of the bottom of the recess 10 in which the electrode portion is disposed. Is formed to be about 5 mm to 0.1 mm.
[0029]
The concave portion 10 is formed by expanding the bottom wall outward as shown in FIGS. 2A, 2C, and 2D, and three annular ribs 261 to 264 are formed concentrically on the bottom surface. And a plurality of ribs 26 are formed radially from the outer peripheral wall surface of the central rib 261 until reaching the inner peripheral surface of the recess 10.
[0030]
The examples shown in FIGS. 3A, 3C, and 3D are examples in which the ribs 263 in FIG. 2 are eliminated.
[0031]
The recess A surrounded by the central rib 261 is a place where a metal vapor deposition film constituting the electrode 5a is formed, and the outer rib 263 (or 262) and the recess B surrounded by the H.264 and the rib 26 are annular. It becomes a place which forms the metal vapor deposition film which comprises the electrode 5b, and these recesses A and B also serve as a mark of the electrode formation place.
[0032]
The electrodes 5a and 5b are formed by forming a metal vapor deposition film of copper, aluminum or the like on the bottom surface of the recess A and the bottom surface of the part B, and forming these metal vapor deposition films. Further, the surface of these electrodes 5a and 5b is subjected to solder plating or gold plating to prevent corrosion to form a protective film.
[0033]
4 (a) to 4 (c) show the state after the electrodes are formed in the moisture sensor housing 1 shown in FIG. 2, and the portion indicated by the mesh line in FIG. 4 (a) shows the electrode 5a or 5b.
[0034]
Here, as an electrode forming method, the deposition is controlled so as to form a metal vapor deposition film in the recesses A and B, or a metal vapor deposition film including the periphery is formed, and the electrodes 5a and 5b are formed after this formation. Although there is any method of selectively peeling and forming so as to remove the part, any method may be adopted as appropriate. FIG. 5 shows a state after the electrodes are formed in the moisture sensor housing 1 shown in FIG. 3. In this case, after forming a metal vapor deposition film between the ribs 262 and 264, the shape of the electrode 5b as shown in FIG. The case where the unnecessary metal vapor deposition film is selectively removed is shown.
[0035]
Since the electrode 5b shown in FIG. 4 or FIG. 5 is formed in a form that is divided by the rib 26, these divided portions are electrically connected by an appropriate method to constitute one annular electrode 5b.
[0036]
FIG. 6 shows an example in which a metal vapor deposition film including the ribs 26 is formed to form the annular electrode 5b. In this case, since the ribs 26 are not electrically separated, There is no need for electrical connection. Further, a selection mask for preventing the rib 26 from being deposited is not required, and the deposition process is simplified.
[0037]
By the way, when the electrode 5b is formed by forming a metal vapor deposition film on the surface of the rib 26 as shown in FIG. 6, the electric field region is also formed in the detection region. May affect the capacitance value. That is, this influence is closely related to the electric field intensity distribution in the detection region, and if the rib pattern is constructed regardless of the electric field direction, the electric field distribution is disturbed unevenly.
[0038]
Therefore, the electric field direction between the central electrode 5a and the electrode 5b in this embodiment is radial and passes through a vertical plane as shown in FIGS. 7A and 7B, so that the rib 26 is substantially parallel to the electric field direction. In this manner, the radial distribution from the center is made perpendicular to the bottom surface of the recess 10 so as to have symmetric regularity, and the electric field distribution in the detection region is symmetrical and uniform. It is supposed to be. In other words, if there is an error in the amount of moisture to be detected when foreign matter is mixed in the object to be detected, in a non-uniform electric field distribution where the electric field density varies, if foreign matter with a large amount of water is mixed in a place where the electric field density is high The error becomes large. On the other hand, if the electric field distribution is uniform, detection errors can be reduced even if foreign matter having a large amount of moisture is mixed.
[0039]
Moreover, since the strength of the moisture sensor housing 1 is increased by forming the ribs 26 and 261 to 264 and the electrodes 5a and 5b are formed of a metal vapor deposition film, cracking of the resin-molded portion and peeling of the electrodes 5a and 5B are caused. Further, since the electrodes 5a and 5b are formed by the metal vapor deposition film, the distance between the electrodes 5a and 5b and the detection sensitivity surface 23, that is, the thickness of the resin molding portion interposed therebetween can be easily managed.
[0040]
As shown in FIG. 8, the circuit board 2 is placed on the column 12 which is integrally provided near the four corners on the bottom surface of the moisture amount sensor casing 1 around the recess 10 and has a hole in the column 12 as shown in FIG. It is fixed by screwing and fastening the fixing screw 13 to 12a. On the circuit board 2, as shown in FIG. 8, an electronic component constituting a moisture sensor circuit block 9 which is a moisture sensor circuit unit is mounted, and a metal plate formed by sheet metal processing so as to cover the electronic component. The shield box 3 is placed and fixed. The circuit on the circuit board 2 and the electrodes 5a and 5b are connected via a lead wire 40. The lid 29 and the operation reference point α of the moisture sensor circuit block 9 on the circuit board 2 are connected by a lead wire 40 ′.
[0041]
As shown in FIG. 9, the moisture amount sensor circuit block 9 includes a capacitance detection circuit 6 that detects a capacitance value Cx of a detection region constituted by an electric field region between a pair of electrodes 5a and 5b that constitute the electrode unit, An output circuit 7 that outputs an electric quantity, for example, a voltage signal, corresponding to the detection capacitance value of the capacitance detection circuit 6, a power supply circuit 8 that supplies operating power to the capacitance detection circuit 6 and the output circuit 7, and these circuits 6 to 8 The capacitor C is connected between the ground reference, that is, the operation reference point α of the capacitance detection circuit 6 and the ground β, and determines the impedance between the operation reference point α of the capacitance detection circuit 6 and the ground β._EAnd is shielded by a shield box 3 deposited on the circuit board 1, and the operation reference point α is connected to the shield box 3. The power supply circuit 8 is configured by, for example, a three-terminal regulator IC.
[0042]
One end of the power supply circuit 8 and the output circuit 7 is connected to the circuit board 1 side circuit, and the other end side is provided at the tip of the cable 20 led out through the shield box 3 and the lid 29 as shown in FIG. The power supply circuit 8 is supplied from the operation panel 14 via the cable 20, and the output signal of the output circuit 7 is supplied to the operation panel 14. Sent out.
[0043]
The shield box 3 electromagnetically shields the moisture sensor circuit block 9. In addition, the recess 10 is filled with an insulator 11 such as silicon rubber to prevent the electrodes 5a and 5b from being short-circuited by the water even when dew condensation occurs in the moisture sensor housing 1.
[0044]
By the way, in this embodiment, the lead wire 40 and the electrode 5b are connected to each other by connecting the core wire 40a of the lead wire 40 at the boundary between the outer peripheral end of the electrode 5b and the rib 264 as shown in FIGS. This is done by soldering. In this case, the ribs 264 serve as walls that prevent the solder 15 from flowing, thereby improving reliability.
[0045]
As shown in FIGS. 11 (a) and 11 (b), a wall 16 having one end connected to the rib 264 and having a parallel portion is erected on the bottom surface of the recess B forming the electrode 5b. The recess 17 formed by the rib 264 may be used as a soldering portion between the lead wire 40 and the electrode 5b, and the wall 16 and the rib 264 may be used to prevent the solder 15 from flowing.
[0046]
Thus, when attaching the moisture sensor 30 of the present embodiment configured as described above to the wall surface of the container 31 containing the detection object X, a window hole opened in the wall surface of the container 31 as shown in FIG. A bulging portion 22 corresponding to the concave portion 10 of the moisture amount sensor housing 1 is fitted to 32 from the outside of the container 31. Here, the amount of protrusion of the bulging portion 22 and the thickness of the wall of the container 31 are set to substantially the same size, and when the bulging portion 22 is fitted into the window hole 32, the amount of moisture around the bulging portion 22 is set. By positioning by directly contacting the outer bottom surface 1a of the sensor housing 1 and the outer wall surface of the container 31, the outer surface of the bulging portion 22 facing the container 31, that is, the detection sensitivity surface 23 is the same as the inner wall surface of the container 31. It arrange | positions so that it may become a surface (surface flush). Then, the moisture sensor 30 is fixed to the container 31 with mounting bolts (not shown) through which holes 28a, 28b, and 28c provided at the four corners of the lid 29, packing 4, and moisture sensor housing 1 are inserted.
[0047]
In this embodiment, by attaching the moisture sensor 30 to the container 31 as described above, the electrodes 5a and 5b do not directly touch the detection target X, and the detection sensitivity surface 23 may protrude into the container 31. Therefore, the detection object X is not buried between the electrodes 5a and 5B and does not obstruct the movement. For example, the detection object X is fermented in the fermentation process, rice, cereals, tea leaves, tobacco leaves, garbage, In any of wood, soil, concrete fine aggregate, and the like, when the electric field region constituted by the pair of electrodes 5a and 5b is set as the detection region, the amount of moisture contained in the detection region is detected by the detection object X being stationary. Even in the middle, or during movement such as stirring and transport, it can be detected in real time without error.
[0048]
In addition, since the electric field distribution is configured to have uniformity, the error can be reduced even if foreign matter is mixed in the detection target X.
[0049]
As shown in FIG. 12A, the electrode 5a is square and the surrounding electrode 5b is formed in a four-frame shape, and the length d0 of one side of the electrode 5a and the width d1 of the electrode 5b are the same dimensions. The distance d2 between the parallel sides of the two may be the same dimension for all four rounds. Also in this case, the influence on the stray capacitance can be reduced.
[0050]
The shape of the central electrode 5a is not a square or a circle, but a rectangle as shown in FIG. 12 (b), an oval as shown in FIG. 12 (c), or an ellipse as shown in FIG. 12 (d). It is also possible to combine the annular electrodes 5b corresponding to the respective shapes.
[0051]
(Embodiment 2)
In the first embodiment, the outer wall surface and the inner wall surface of the container 31 containing the detection target object X correspond to flat surfaces, but at least the inner wall surface is a curved surface. The detection sensitivity surface 23 cannot be flush with the inner wall surface of the container 31.
[0052]
Therefore, in this embodiment, as shown in FIGS. 13 to 15, the outer surface of the bulging portion 22, that is, the detection sensitivity surface 23 is curved so as to be flush with the arcuate inner wall surface of the container 31. In this case, the wall of the bulging portion 22, that is, the bottom wall of the recess 10 is substantially equal in thickness, and the distance between the electrodes 5 a and 5 b formed of a metal vapor deposition film on the bottom of the recess 10 and the detection sensitivity surface 23 is made equal. .
[0053]
In addition, since the other structure is the same structure as Embodiment 1, in FIG. 13 thru | or FIG. 15, the same code | symbol is attached | subjected to the same component as the component of Embodiment 1, and description is abbreviate | omitted.
[0054]
In FIGS. 13 and 14, the ribs 26 and 261 to 264 are not shown.
[0055]
(Embodiment 3)
In the first and second embodiments, the moisture sensor circuit block 9 is covered with the shield box 3. In other words, the shield box 3 can be shielded even when an FM broadcast or amateur radio frequency that matches the frequency band (several tens of MHz to several hundreds of MHz) used in the moisture sensor circuit block 9 is reached, and the cause of malfunction is eliminated. It prevents radiation waves from being radiated from the inside to eliminate the risk of causing malfunction of external devices.
[0056]
However, in the configuration in which the shield box 3 is made of metal parts, the number of parts increases, the part cost increases, and the assembly cost also increases.
[0057]
Therefore, in the present embodiment, similarly to the electrodes 5a and 5b, a shield part made of a metal vapor deposition film is configured to reduce the number of parts and the cost.
[0058]
That is, as shown in FIGS. 16A and 16B, the moisture sensor around the inner surface of the peripheral wall of the moisture sensor housing 1 and the bottom surface, the inner peripheral surface of the concave portion 10 located outside the electrode 5b, and the periphery of the concave portion 10. A metal vapor deposition film (shown by a mesh line) is formed on the bottom surface of the housing 1 in the same manner as the electrodes 5a and 5b, and the shield portion 27 is configured by this metal vapor deposition film.
[0059]
Therefore, by attaching the metal lid 29 to the opening of the moisture sensor housing 1, the interior of the moisture sensor housing 1 can be shielded by the lid 27 and the shield portion 27, so that the incoming radio wave It is possible to prevent intrusion into the inside and leakage of radio waves emitted from the internal moisture amount sensor circuit block 9 to the outside.
[0060]
Here, the lid 29 and the operation reference point α of the moisture sensor circuit block 9 on the circuit board 2 are connected by the lead wire 40 ′ as in the first embodiment (see FIGS. 8 and 9). In this embodiment, the metal vapor deposition film and the operation reference point α of the moisture amount sensor circuit block 9 on the circuit board 1 are connected as follows.
[0061]
That is, as shown in FIG. 17A, the metal vapor deposition film of the shield portion 27 is also formed on one surface of the four columnar bodies 12 integrally projecting as a structure on the bottom surface of the moisture sensor housing 1. Is formed as a conductive portion 27a, and is connected to the circuit of the circuit board 1 mounted on the column 12 and fixed by the fixing screw 13 through the conductive portion 27a made of the metal vapor-deposited film. It is like that.
[0062]
Therefore, on the back side of the circuit board 1, as shown in FIG. 17 (c), around the opening of the screw insertion hole 19 corresponding to the screw screw hole 12a of the column 12 on which the metal vapor deposition film 27a is formed. The conductive pattern 18 is formed, and the other end of the conductive pattern 33 having one end connected to the operation reference point α of the moisture amount sensor circuit block 9 is screwed on the surface side of the circuit board 1 as shown in FIG. When the fixing screw 15 is formed to extend to the opening edge of the insertion hole 19 and is inserted into the screw insertion hole 19 from the surface side of the circuit board 1 and screwed into the hole 12a of the pillar body 12, the mounting on the circuit board 1 side is performed. The conductive pattern 18 provided on the mounting surface is in pressure contact with the conductive portion 27a made of a metal vapor deposition film on the front end surface of the column body 12, and the head of the fixing screw 13 is in pressure contact with the conductive pattern 33 on the surface side. , Conductive pattern 33, fixing screw 13, conductive pattern 18, the shield part 27 is electrically connected to the operation reference point α through the path of the conductive part 27a made of the metal vapor deposition film of the column 12 and the shield part 27.
[0063]
FIG. 18 is a cross-sectional view of a schematic configuration in a state where the present embodiment is attached to the container 31. Since the configuration is the same as that of the first and second embodiments, it is not particularly shown here.
[0064]
(Embodiment 4)
In the third embodiment, the electrical connection between the fixing screw 13 and the shield portion 27 and the operation reference point α of the moisture amount sensor circuit block 9 on the circuit board 1 is the column body 12 on which the metal vapor deposition film 27a is formed, Although the conductive patterns 18 and 33 and the fixing screw 13 are used, in this embodiment, as shown in FIG. A conductive portion 27a made of a metal vapor deposition film is formed on the surface of the higher column 12 ', and an insertion hole 34 through which the tip of the column 12' is inserted is shown in FIG. 19 and a conductive pattern 33 having one end connected to the operation reference point α of the moisture sensor circuit block 9 on the surface side of the circuit board 1 as shown in FIG. To the circuit base with the fixing screw 13 The plate 1 is fixed to the column body 12 other than the column body 12 ′ having the conductive portion 27 a formed on the surface thereof.
[0065]
The upper end surface of the column 12 'faces the front side through the insertion hole 34, and the metal vapor deposition film 27a on the upper end surface and the conductive pattern 33 are electrically connected by the lead wire 35, whereby a moisture amount sensor. The shield part 27 is electrically connected to the operation reference point α (see FIG. 9) of the circuit block 9 through the conductive pattern 33, the lead wire 35, and the conductive part 27a made of the metal vapor deposition film of the column 12 ′. To do.
[0066]
FIG. 20 is a sectional view of a schematic configuration in a state where the present embodiment is attached to the container 31. Since the configuration is the same as that of the first and second embodiments, it is not particularly shown here.
[0067]
(Embodiment 5)
In the third and fourth embodiments, the shield body 27 is connected to the operation reference point α of the moisture amount sensor circuit block 9 on the circuit board 1 by using the column body 12 ′ provided for supporting and fixing the circuit board 1. In this embodiment, as shown in FIG. 21, for example, as shown in FIG. 21, the connection is connected to the input end of the capacitance detection circuit 6 of the moisture amount sensor circuit block 9 on the circuit board 1 side via the lead wire 38. The structure 36 in which the male connector portion CN2 corresponding to the female connector CN1 is integrally provided at the tip is integrally provided on the bottom surface of the moisture sensor housing 1 and electrically connected to the female connector CN1. Metal deposition is performed over the bottom surface of the moisture sensor housing 1 and the surface of the structure 36 in order to electrically connect the pin 37, which is a connection conductor of the connector portion CN2 to be connected, and the electrodes 5a, 5b, for example. Conductive film It is formed with 27a '.
[0068]
Thus, in the present embodiment, the connection between the capacitance detection circuit 6 of the moisture sensor circuit block 9 on the circuit board 1 and the electrodes 5a and 5b connects the female connector CN1 to the male connector portion CN2 of the structure 36. Can be done. Reference numeral 39a denotes a locking piece provided on the male connector portion CN2 side. The elastic locking claw piece 39b of the female connector CN1 is detachably locked to the locking piece 39a to prevent the connector CN1 from coming off. I am trying.
[0069]
In this embodiment, it is used for connecting electrodes, but it may be used for connecting a shield part or the like.
[0070]
【The invention's effect】
The invention according to claim 1 is an electrode in which an electric field region constituted by a pair of electrodes is a detection region, and a surface in which at least one of the pair of electrodes is in contact with a detection target via an insulator is a detection sensitivity surface. And a capacitance detection circuit for detecting a capacitance value determined by the amount of moisture present in the detection region, and an electric signal having an amount of electricity corresponding to the amount of moisture from the capacitance value detected by the capacitance detection circuit A capacitance sensor circuit unit comprising at least a moisture sensor circuit unit configured to output an output circuit, wherein the electrode in contact with the object to be detected via the insulator is opposite to the detection sensitivity surface. Since it is formed with a metal vapor deposition film deposited on the surface of the insulator, the amount of water contained in the detection target can be detected in real time even when the detection target is moving as well as stationary. Yes Since at least one of the pair of electrodes constituting the electrode portion does not directly touch the object to be detected, the electrode can be easily cleaned, and the phenomenon that the electrode is dissolved by metal ions in moisture can be prevented. Because it is protected, wear on the detection sensitivity surface becomes uniform, and it becomes difficult to make unevenness on the sensitivity detection surface so that the flow of the detection object is obstructed. When there is no possibility that the detection object will be buried between the other electrode and the electrode is bonded even if a load due to the detection object is applied to the detection sensitivity surface of the insulator And when the electrode surface needs to be curved in accordance with the curved surface of the detection sensitivity. Electrode formation Come, there is an effect that management of the distance to the electrodes and the detection sensitivity surface easily.In addition, since the rib is integrally provided on the surface of the insulator that forms the electrode by depositing the metal deposition film, the strength of the insulator can be increased, and the insulator can be prevented from bending and cracking. There is an effect that can be.
[0073]
Claim2In the invention of claim1In this invention, since the rib is vertically formed on the insulator surface so as to be substantially parallel to and substantially perpendicular to the direction of the electric field generated between the pair of electrodes, the presence of the rib is caused by the electric field distribution in the detection region. Will not be uneven.
[0074]
Claim3The invention according to claim 1 or 2 is characterized in that, in the invention of claim 1 or 2, the circuit board on which the moisture amount sensor circuit portion is mounted and the electrode made of the metal vapor deposition film are connected by a lead wire by soldering, and the lead wire to the electrode Since the connection portion by soldering is the end portion of the electrode at the boundary position with the rib existing at the metal vapor deposition film forming position, the rib serves as a wall that prevents the flow of solder, and the reliability can be improved.
[0075]
Claim4In the invention of claim1 or 2In the invention, the circuit board on which the moisture sensor circuit unit is mounted and the electrode made of the metal vapor deposition film are connected by a lead wire by soldering, and the connection part by soldering the lead wire to the electrode is connected to the electrode Since the recess is provided in the electrode formation position, the wall surface of the recess becomes a wall that prevents the flow of solder, and the reliability can be improved.
[0076]
Claim5The invention of claim 1 to claim 14In any one of the inventions, the insulator is a part of a moisture sensor housing that is a resin molded product that houses a circuit board on which the moisture sensor circuit unit is mounted, and the inner surface of the moisture sensor housing Has a radio wave shield part made of a metal deposition film electrically connected to the 0 V potential point of the moisture sensor circuit part, so that the radio wave shield part can shield external radio waves and Prevents malfunctions, prevents leakage of radiated radio waves from the inside, eliminates the influence on external equipment, and does not increase the number of parts compared to the case of producing a shield case with metal parts, and the parts cost In addition, the assembly cost is low because it is inexpensive and does not require an assembling process.
[0077]
Claim6The invention of claim 1 to claim5In any one of the inventions, the insulator is a part of a moisture sensor housing that is a resin molded product that houses a circuit board on which the moisture sensor circuit unit is mounted. Is provided with a structure for forming a conductive part on the surface of the metal vapor deposition film and electrically connecting the electrode or shield part and the circuit of the circuit board through the conductive part. Compared with the case where the connection between the electrode and the circuit board side is performed using a lead wire, the wiring in the moisture sensor housing can be performed in an orderly manner.
[0078]
Claim7In the invention of claim6In this invention, the structure is formed integrally with the moisture sensor housing, and has a screw screw hole formed in the tip surface, and the circuit board is placed and supported on the tip surface. The circuit board is supported and fixed by fastening a fixing screw that is screwed into the screw screw hole through the insertion hole provided on the side, and is provided on the mounting surface on the circuit board side by fastening the fixing screw. Since the pattern and the conductive portion located on the front end surface of the structure are pressed against each other, the circuit board side can be electrically connected to the shield part or electrode and the circuit board side simultaneously with the placement and fixing of the circuit board.
[0079]
Claim8In the invention of claim6In this invention, the structure is formed integrally with the moisture sensor housing, and the tip is inserted into the insertion hole formed in the circuit board from the back side of the circuit board and exposed to the front side of the circuit board. Since the conductive part on the surface of the tip part and the conductive pattern on the circuit board surface side are electrically connected, the electrical connection between the shield part or electrode and the circuit board side can be performed on the circuit board surface side. Thus, the wiring can be performed in an orderly manner as compared with the case where the lead wires are wired in the space below the circuit board.
[0080]
Claim9In the invention of claim6In the invention, a connector portion for connecting a connector to be connected from the circuit board side is provided at a tip portion of the structure body, a connection conductor of the connector portion to be electrically connected to the connector to be connected, and the structure body Since the conductive portion is electrically connected, the electrical connection between the shield part or electrode and the circuit board side can be performed easily and quickly.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a first embodiment.
FIG. 2 (a) is a plan view of an example of the moisture sensor housing of the above.
(B) is a side view of an example of a moisture amount sensor housing | casing same as the above.
(C) is a sectional side view of an example of the moisture amount sensor housing of the above.
(D) is the II sectional view of the same figure (a).
FIG. 3 (a) is a plan view of another example of the moisture sensor housing of the above.
(B) is a side view of another example of the moisture sensor housing of the above.
(C) is a sectional side view of another example of the moisture amount sensor housing of the above.
(D) is the II sectional view of the same figure (a).
FIG. 4 (a) is a plan view of an example of the moisture sensor housing after the electrodes are formed.
(B) is a side view of an example after the electrode formation of the moisture amount sensor housing | casing same as the above.
(C) is a sectional side view of an example after electrode formation of the moisture amount sensor casing same as above.
(D) is the II sectional view of the same figure (a).
FIG. 5 is a plan view of another example after the electrodes of the moisture sensor housing are formed.
FIG. 6 is a plan view of another example after the electrode formation of the moisture sensor housing of the above.
FIG. 7 is an explanatory diagram of the direction of ribs formed on the moisture sensor housing.
FIG. 8 is a cross-sectional view of the same as above attached to a container.
FIG. 9 is a circuit configuration diagram of the moisture sensor circuit block of the above.
FIG. 10A is an enlarged top view in which a part of the connection portion between the electrode and the lead wire can be omitted.
(B) is an enlarged sectional view in which a part of the connection portion between the electrode and the lead wire can be omitted.
FIG. 11 (a) is an enlarged top view in which another example of the connection portion between the electrode and the lead wire can be partially omitted.
(B) is an enlarged cross-sectional view that can omit a part of another example of the connection portion between the electrode and the lead wire.
FIG. 12 is an explanatory diagram of another example of the electrode shape of the above.
13 is a sectional view of Embodiment 2. FIG.
FIG. 14 (a) is a schematic plan view of the moisture content sensor casing of the above.
(B) is a schematic sectional side view of the moisture content sensor housing | casing same as the above.
(C) is a schematic sectional side view showing the filling state of the filling of the moisture sensor housing of the above.
FIG. 15 (a) is a plan view of the moisture sensor housing of the above.
(B) is a side view of the moisture sensor housing of the above.
(C) is a side view of the moisture amount sensor housing of the above.
FIG. 16A is a plan view of a moisture sensor housing of the third embodiment.
(B) is a side view of the moisture sensor housing of the above.
(C) is a sectional side view of the moisture sensor housing of the above.
FIG. 17 (a) is a schematic plan view of the moisture amount sensor casing of the above.
(B) is a schematic plan view of a circuit board arrangement state of the moisture sensor housing of the above.
(C) is a bottom view of the same circuit board.
FIG. 18 is a schematic cross-sectional view of the same as above attached to a container.
FIG. 19 (a) is a schematic plan view of a moisture sensor housing of the fourth embodiment.
(B) is a schematic plan view of a circuit board arrangement state of the moisture sensor housing of the above.
(C) is a bottom view of the same circuit board.
FIG. 20 is a schematic cross-sectional view of the same as above attached to a container.
FIG. 21 is an exploded perspective view in which a part of the main part of the fifth embodiment can be omitted.
FIG. 22 is an explanatory diagram of the principle of a capacitance type moisture amount detection sensor.
FIG. 23 is an explanatory diagram of the relationship between the detected capacitance value and the amount of moisture.
FIG. 24A is a plan view in which a part of a conventional electrode portion can be omitted.
(B) is a circuit connection diagram same as the above.
[Explanation of symbols]
1 Moisture sensor housing
2 Circuit board
3 Shield box
4 Packing
5a, 5b electrode
10 recess
29 lid

Claims

An electric field region constituted by a pair of electrodes is used as a detection region, and an electrode portion in which at least one of the pair of electrodes is in contact with a detection target via an insulator has a detection sensitivity surface; and within the detection region At least from a capacitance detection circuit that detects a capacitance value determined by the amount of water present in the capacitor, and an output circuit that outputs an electrical signal having an amount of electricity corresponding to the amount of moisture from the capacitance value detected by the capacitance detection circuit A capacitance type moisture sensor comprising a moisture sensor circuit unit configured, wherein the electrode in contact with the object to be detected via the insulator is placed on the surface of the insulator opposite to the detection sensitivity surface. A capacitance type moisture sensor characterized in that it is formed by a vapor deposited metal vapor deposition film, and a rib is integrally provided on the surface of the insulator on which the metal vapor deposition film is vapor deposited to form an electrode .

2. The capacitance type moisture content according to claim 1, wherein said rib is vertically formed on said insulator surface so as to be substantially parallel to and substantially perpendicular to a direction of an electric field generated between a pair of electrodes. Sensor.

The circuit board on which the moisture sensor circuit unit is mounted and the electrode made of the metal vapor deposition film are connected by lead wires by soldering, and the connection portion by soldering the lead wire to the electrode is connected to the metal vapor deposition film formation position. capacitive moisture content sensor according to claim 1 or 2 Symbol mounting, characterized in that the end of the electrode at the boundary position between the ribs present in the.

The circuit board on which the moisture sensor circuit unit is mounted and the electrode made of the metal vapor deposition film are connected by lead wires by soldering, and the connection site by soldering of the lead wires to the electrodes is defined as the formation position of the electrodes. The electrostatic capacity type moisture sensor according to claim 1 or 2 , characterized in that it is in a recess provided inside .

The insulator is a part of a moisture sensor housing that is a resin molded product that houses a circuit board on which the moisture sensor circuit unit is mounted, and the moisture sensor circuit is disposed on the inner surface of the moisture sensor housing. capacitive moisture content sensor according to any one of claims 1 to 4, characterized in that by forming a radio wave shield according 0V potential point electrically connected to the metal evaporated film parts.

The insulator is a part of a moisture sensor housing that is a resin molded product that houses a circuit board on which the moisture sensor circuit unit is mounted, and the moisture sensor housing is electrically conductive by a metal vapor deposition film. and the electrode or the shield portion through the conductive portion to form a part on the surface, any of claims 1 to 5, characterized in that it comprises providing a structure for electrically connecting the circuit of the circuit board Or a capacitive moisture sensor.

The structure is formed integrally with the moisture sensor housing, and has a screw screw hole in the front end surface, and the circuit board is placed and supported on the front end surface and provided on the circuit board side. The conductive pattern and the structure provided on the mounting surface on the circuit board side by supporting and fixing the circuit board by fastening the fixing screw screwed into the screw screw hole through the insertion hole. 7. The capacitance type moisture sensor according to claim 6, wherein the conductive portion located on the tip surface of the electrode is pressed into contact with the conductive portion .

The structure is formed integrally with the moisture sensor housing, and the tip is inserted into the insertion hole formed in the circuit board from the back side of the circuit board and exposed to the front side of the circuit board. 7. The capacitance type moisture sensor according to claim 6 , wherein the conductive portion on the surface is electrically connected to the conductive pattern on the surface side of the circuit board .

A connector part for connecting the connector to be connected from the circuit board side is provided at the tip of the structure body, and a connection conductor of the connector part to be electrically connected to the connector to be connected, and the conductive part of the structure body And a capacitance type moisture sensor according to claim 6 .