JP2004206616A

JP2004206616A - Glass breakage sensor

Info

Publication number: JP2004206616A
Application number: JP2002377837A
Authority: JP
Inventors: Kiwamu Shibata; 究柴田; Hideo Mori; 秀夫森
Original assignee: Matsushita Electric Works Ltd
Current assignee: Panasonic Electric Works Co Ltd
Priority date: 2002-12-26
Filing date: 2002-12-26
Publication date: 2004-07-22
Anticipated expiration: 2022-12-26
Also published as: JP4032967B2

Abstract

<P>PROBLEM TO BE SOLVED: To prevent breakage of a piezoelectric element due to an ambient environmental temperature change in a glass breakage sensor detecting an invader. <P>SOLUTION: This glass breakage sensor is provided with a disk-shaped piezoelectric element 2 fixed inside a molded housing 1, which is attached to a glass pane G by a double-sided adhesive sheet, to convert vibration of the glass pane G into a voltage signal. The glass breakage sensor outputs an alarm if amplitude of an output signal from the piezoelectric element 2 is larger than an alarm threshold value. The piezoelectric element 2 is stuck to the housing 1 by means of an adhesive 3 with a Shore hardness A≤40. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、室内外を仕切るガラス板に取り付けられガラス板の破壊を検知するガラス破壊センサに関するものである。
【０００２】
【従来の技術】
従来から、窓ガラスやガラス扉など室内外を仕切るガラス板に取り付けられ、室内に侵入しようとする者（以下、侵入者）がガラス板を破壊したときにこれを検知して音や光によって報知する防犯用のガラス破壊センサが提供されている。この種のガラス破壊センサは、振動検知手段としてガラス板の振動を電圧信号に変換する圧電素子を用いて、警報閾値よりも圧電素子の出力信号の振幅が大きければ警報を出力するもので、一般に図２、図３に示すようにガラス破壊センサの外郭を形成してガラス板に取り付けられるハウジング１が成形品である場合、円板状の圧電素子２をハウジング１に接着剤３で貼り付けていた。
【０００３】
また、圧電素子２をハウジング１に接着剤３を使って固定する場合図１８に示すように、接着剤３の塗布量と硬化時に圧電素子２に加える荷重とを管理することで接着剤層の厚みを管理していた。
【０００４】
あるいは、ハウジングの接着面に凹部を設けて、凹部の深さに応じた接着剤層を形成したり、ハウジングの接着面に凸部を設けて、凸部の高さに応じた接着剤層を形成したりして、接着剤層の厚みを管理していた。（例えば、特許文献１参照。）
さらに圧電素子２は図２に示すように、ハウジング１との接着面（裏面）と、接着面に対向する面（表面）とに各々電極２１を形成しており、非金属のハウジング１に接着する場合は、ハウジング１に接着する裏面の電極２１からの信号を取り出すために圧電素子２の裏側の電極２１から側面へ延長され圧電素子２の表面側に引き出す折り返し電極２２の電極パターンを形成している。表面の電極２１及び折り返し電極２２は各々、電線５を介して回路部と電気的に接続されている。
【０００５】
【特許文献１】
特開平６−６１２７６号公報（２頁左欄第２４行〜第２７行、２頁右欄第１９行〜第４８行、図１〜図４）
【０００６】
【発明が解決しようとする課題】
しかし、上述した従来のガラス破壊センサでは接着剤３として硬度の高いエポキシ系接着剤等を用いており、圧電素子２を成形品のハウジング１に貼り付けると、図１９に示すように、周囲環境の温度変化によりハウジング１が図中破線のように変形し、その歪み（例えば接着面に対して垂直なＹ１，Ｙ２方向）が接着剤３を介して圧電素子２に伝わり、ハウジング１と接着剤３及び圧電素子２との線膨張係数の違いにより圧電素子２がハウジング１の変形に追従できずに破損するという問題があった。
【０００７】
本発明は、上記事由に鑑みてなされたものであり、その目的は、周囲環境の温度変化による圧電素子の破損を防止したガラス破壊センサを提供することにある。
【０００８】
【課題を解決するための手段】
請求項１の発明は、建物において室内外を仕切るガラス板に取り付けられるハウジングと、前記ハウジングに接着剤で固定されて前記ガラス板の振動を電圧信号に変換する圧電素子と、警報閾値よりも前記圧電素子の出力信号の振幅が大きければ警報を出力する報知手段とを備え、前記接着剤は、硬化後の硬度がショア−硬度Ａで４０以下であることを特徴とする。
【０００９】
請求項２の発明は、建物において室内外を仕切るガラス板に取り付けられるハウジングと、前記ハウジングに接着剤で固定されて前記ガラス板の振動を電圧信号に変換する圧電素子と、警報閾値よりも前記圧電素子の出力信号の振幅が大きければ警報を出力する報知手段とを備え、前記ハウジングは、前記圧電素子の接着面を囲むように前記圧電素子の周囲に立設した壁を有することを特徴とする。
【００１０】
請求項３の発明は、請求項１または２において、前記ハウジングは、前記圧電素子が接着される箇所に、前記圧電素子を載置して予め定めた接着剤層の厚みに相当する同一高さの複数の凸部を備え、前記複数の凸部は、載置される前記圧電素子が前記ハウジングに対する平行度を維持できる箇所に各々配置されることを特徴とする。
【００１１】
請求項４の発明は、請求項１または２において、前記ハウジングは、前記圧電素子が接着される箇所に、前記圧電素子の接着面の周縁部を載置する台部と、前記台部の内側に形成されて予め定めた接着剤層の厚みに相当する一定深さの凹部とを備え、前記台部は、載置された前記圧電素子が前記ハウジングに対する平行度を維持できる形状に形成されることを特徴とする。
【００１２】
請求項５の発明は、請求項１乃至４いずれかにおいて、前記圧電素子は、接着面と該接着面に対向する面とに各々電極を設け、外面の少なくとも一部を前記電極の対向方向に段差を設けた階段形状としたことを特徴とする。
【００１３】
請求項６の発明は、請求項１乃至４いずれかにおいて、前記圧電素子は、接着面と該接着面に対向する面とに各々電極を設け、前記電極間の絶縁距離は前記電極の対向方向の厚みの少なくとも一部を含むことを特徴とする。
【００１４】
【発明の実施の形態】
以下、本発明の実施の形態を図面に基づいて説明する。
【００１５】
（実施形態１）
本実施形態のガラス破壊センサは図１（ａ）に示すように、ガラス板Ｇに両面粘着シートによって取り付けられる成形品のハウジング１内に固定されてガラス板Ｇの振動を電圧信号に変換する円板状の圧電素子２を備えて、警報閾値よりも圧電素子２の出力信号の振幅が大きければ警報を出力するもので、その回路部の構成は図１（ｂ）に示すように、圧電素子２に並列接続された抵抗Ｒ１と、圧電素子２の出力信号のうちガラス板Ｇの破壊に関わる周波数が通過しノイズが除去される程度にカットオフ周波数が設定されたハイパスフィルタ回路Ｓ１と、ハイパスフィルタ回路Ｓ１の出力と警報閾値電圧Ｖｔｈとを比較する比較判断部Ｓ２と、比較判断部Ｓ２の判断結果が、警報閾値電圧Ｖｔｈよりもハイパスフィルタ回路Ｓ１の出力が大きければ警報を発する警報出力部Ｓ３とから構成される。
【００１６】
圧電素子２は図２、図３に示すようにハウジング１に接着剤３で貼り付けられ、従来例と同様に表面の電極２１及び折り返し電極２２は各々、電線５を介して図１（ｂ）に示す回路部と電気的に接続されている。
【００１７】
本実施形態では、接着剤３にショア−硬度Ａ＝４０以下のもの、例えばシリコン系接着剤を用いている点が従来例と異なる。
【００１８】
次に、この圧電素子２を硬度の各々異なる接着剤３で成形品のハウジング１に貼りつけたサンプルについて、周囲環境の温度変化に対して圧電素子２の破損の有無を確認するために、熱衝撃試験により破損状況の有無の確認を行った。サンプルとして、接着剤３ａ：ショア−硬度Ｄ＝８９（ショア−硬度Ａ＝９０以上）、接着剤３ｂ：ショア−硬度Ｄ＝７５（ショア−硬度Ａ＝９０以上）、接着剤３ｃ：ショア−硬度Ｄ＝４０（ショア−硬度Ａ＝９０）、接着剤３ｄ：ショア−硬度Ａ＝４０の４種類を用意した。尚、試験条件は使用温度範囲に対し低温側高温側ともに２５℃拡張した−４０℃〜８０℃で、５０サイクルという厳しい条件とした。
【００１９】
熱衝撃試験の結果は図４に示すように、接着剤３ａ，３ｂを用いたサンプルは、圧電素子２が厚み方向で２つに分断され、接着剤３ｃを用いたサンプルは、サンプルの一部が破損、あるいは電極部分の剥離による感度劣化を起こしていた。しかし、接着剤３ｄを用いたサンプルは破損、感度劣化共なかった。したがって本実施形態では接着剤３にショア−硬度Ａ＝４０以下のものを用いることで、ハウジング１と圧電素子２との間で接着剤３が各々の線膨張係数の違いによる伸縮を吸収する形となって、圧電素子２の破損をなくすことができる。
【００２０】
（実施形態２）
本実施形態のガラス破壊センサの基本構成は実施形態１と略同様であり、同様の構成には同一の符号を付して説明は省略する。図５、図６は本実施形態のハウジング１と円板状の圧電素子２との接着部分を示しており、ハウジング１は圧電素子２の接着面を囲むように圧電素子２の外周に沿って立設した円環状の壁１０を一体成形している。圧電素子２はこの一体成形した壁１０の内側でハウジング１に接着剤３で貼り付けられているので、周囲環境の温度変化によりハウジング１が図６中破線のように変形しようとしても壁１０の剛性によって接着面の変形（そり）を抑えることができ、接着面に平行なＸ１，Ｘ２方向に働く伸縮力も大幅に削減されている。
【００２１】
したがって、圧電素子２の接着面の変形は少なく、圧電素子２に歪みが伝わらないために硬度の高い接着剤３を使用しても圧電素子２の破損はない。尚、図５、図６の壁１０の平面形状は円となっているが、圧電素子を囲むことのできる形状であれば、その他の形状、例えば矩形であっても対応は可能である。
【００２２】
（実施形態３）
図７（ａ），（ｂ）は、本実施形態のハウジング１と円板状の圧電素子２との接着部分を示し、他の構成は実施形態１または２と同様であり、同様の構成には同一の符号を付して説明は省略する。本実施形態のハウジング１の圧電素子２を接着する部分には、円形の凹部１２を形成し、凹部１２の底面上にその高さが予め定めた接着剤層の厚みＴ１と一致する凸部１１ａ〜１１ｃを３ヶ所配置する。凸部１１ａ〜１１ｃは、その各中心が圧電素子２の円形の接着面の中心位置に対して１２０°間隔となるように同心円上に配置され、圧電素子２はこの凸部１１ａ〜１１ｃに載置されてハウジング１に対する平行度を保っている。
【００２３】
ここで従来、図１８のように圧電素子２をハウジング１に接着剤３を使って固定する場合、硬化後の接着剤層厚みの管理が難しくセンサの振動検出感度にバラツキがあるという問題があった。しかし、本実施形態のように圧電素子２の接着部分に接着剤３を塗布し、圧電素子２を凸部１１ａ〜１１ｃ上に置いて接着剤３を硬化させると、接着剤層の厚みＴ１は凸部１１ａ〜１１ｃの高さで決まるため振動の伝達経路の厚み（接着剤層の厚みＴ１）が一定となり、センサの振動検出感度のバラツキは小さくなり、一定の範囲内に収まる。
【００２４】
また、凸部１１ａ〜１１ｃの代わりに図８に示す円環状の凸部１３や、図９に示す互いに平行に配置された１対の直線状の凸部１４ａ，１４ｂであってもよく、接着剤層の厚みＴ１及び圧電素子２のハウジング１に対する平行度を保つことできるものであればよい。
【００２５】
（実施形態４）
図１０（ａ），（ｂ）は、本実施形態のハウジング１と円板状の圧電素子２との接着部分を示し、他の構成は実施形態１または２と同様であり、同様の構成には同一の符号を付して説明は省略する。本実施形態のハウジング１の圧電素子２を接着する部分には、円形の凹部１２を形成し、凹部１２よりその径が小さく、その深さが予め定めた接着剤層の厚みＴ１と一致する円形の凹部１５を凹部１２の底面に形成する。圧電素子２はその接着面の周縁部を凹部１２の円周部（台部）上に載置されてハウジング１に対する平行度を保っている。
【００２６】
ここで従来、図１８のように圧電素子２をハウジング１に接着剤３を使って固定する場合、硬化後の接着剤層厚みの管理が難しくセンサの振動検出感度にバラツキがあるという問題があった。しかし、本実施形態のように圧電素子２の接着部分に接着剤３を塗布し、圧電素子２を凹部１２の円周部上に置いて接着剤３を硬化させると、接着剤層の厚みＴ１は凹部１５の深さで決まるため振動の伝達経路の厚み（接着剤層の厚みＴ１）が一定となり、センサの振動検出感度のバラツキは小さくなり、一定の範囲内に収まる。
【００２７】
また、凹部１５の形状は四角等、接着剤層の厚みＴ１及び圧電素子２のハウジング１に対する平行度を保つことできる形状であればよい。
【００２８】
（実施形態５）
図１１、図１２は、本実施形態の圧電素子２を示し、他の構成は実施形態１乃至４いずれかと同様であり、同様の構成には同一の符号を付して説明は省略する。本実施形態の圧電素子２は、径の異なる円板状の素子部２ａ，２ｂの一方の側端部同士を一致させて重ねた２段構成となっており、径が小さい素子部２ａの裏面は、非金属のハウジング１との接着面であると共に電極２１を全面に形成している。また素子部２ｂの表面にも素子部２ａと同径に形成されたもう一方の電極２１が形成される。ここで、圧電素子２の表裏面の各電極２１の径は、検出周波数での感度を確保するために検出周波数で決まる径Ｒ１となる。
【００２９】
そして素子部２ａの裏面の電極２１から素子部２ａの側面、素子部２ｂの裏面及び側面にまで延長した延長電極２３が形成されており、素子部２ｂの裏面の延長電極２３に予め電線を半田付けしておいてからハウジング１に貼り付け、回路部に配線する。素子部２ｂの表面に形成されたもう一方の電極２１も回路部に配線される。
【００３０】
ここで従来、図２のように折り返し電極２２の電極パターンの圧電素子２を製造する場合、セラミックを分極する際に２つの電極間同士の絶縁距離を確保するために圧電素子２の厚み相当の距離を開ける必要があるため、両面全面電極パターンに比べ感度が低いという問題があった。
【００３１】
しかし本実施形態では、圧電素子２の厚み方向は階段状に形成されているので、表裏面の各電極２１間の絶縁距離Ｚ１は十分に確保できると同時に、検出周波数で決まる電極２１の径Ｒ１の部分すべてが分極処理されるため、従来の折り返し電極パターンに比べて感度は向上する。なお、素子部２ｂ側面の延長電極２３は無くてもよい。
【００３２】
また図１３、図１４に示すように、径の異なる円板状の素子部２ａ，２ｂの中心同士を一致させて重ねた２段構成としても同様の効果を得ることができる。図１３、図１４では素子部２ｂ側面には延長電極２３はなく、表裏面の各電極２１間の絶縁距離Ｚ２となり、素子部２ｂ側面の延長電極２３がある場合の絶縁距離Ｚ１に比べて素子部２ｂの厚み分だけ絶縁距離を大きくとることができる。
【００３３】
さらに本実施形態では圧電素子２の厚み方向の形状を階段状にしてあるが、図１５に示すように素子部２ｂの側面を、表面に近付くにしたがって径が小さくなるスロープ状に形成しても問題は無い。
【００３４】
（実施形態６）
図１６、図１７は、本実施形態の圧電素子２を示し、他の構成は実施形態１乃至４いずれかと同様であり、同様の構成には同一の符号を付して説明は省略する。本実施形態の圧電素子２は、同一径の円板状の素子部２ｄ，２ｆの間に素子部２ｅ，２ｆより径の大きい円板状の素子部２ｅを挟んだ３段構成となっており、素子部２ｄの表面及び素子部２ｆの裏面は電極２１を全面に形成しており、素子部２ｆの裏面を非金属のハウジング１との接着面としている。ここで、圧電素子２の表裏面の各電極２１の径は、検出周波数での感度を確保するために検出周波数で決まる径Ｒ１となる。
【００３５】
そして素子部２ｄの表面の電極２１から素子部２ｄの側面、素子部２ｅの表面にまで延長した延長電極２３、及び素子部２ｆの裏面の電極２１から素子部２ｆの側面、素子部２ｅの裏面にまで延長した延長電極２３が各々形成されており、素子部２ｆの裏面の延長電極２３に予め電線を半田付けしておいてからハウジング１に貼り付け、回路部に配線する。素子部２ｂの表面に形成されたもう一方の電極２１も回路部に配線される。
【００３６】
本実施形態では、素子部２ｅの厚みを表裏面の各電極２１間の絶縁距離Ｚ３としており、絶縁距離は十分に確保できると同時に、検出周波数で決まる電極２１の径Ｒ１の部分すべてが分極処理されるため、従来の折り返し電極パターンに比べて感度は向上する。さらに、実施形態５に比べて構造体の対称性を確保してあるため、スプリアスも抑えることができる。
【００３７】
【発明の効果】
請求項１の発明は、建物において室内外を仕切るガラス板に取り付けられるハウジングと、前記ハウジングに接着剤で固定されて前記ガラス板の振動を電圧信号に変換する圧電素子と、警報閾値よりも前記圧電素子の出力信号の振幅が大きければ警報を出力する報知手段とを備え、前記接着剤は、硬化後の硬度がショア−硬度Ａで４０以下であるので、ハウジングと圧電素子との間で接着剤が各々の線膨張係数の違いによる伸縮を吸収し、周囲環境の温度変化による圧電素子の破損を防止することができるという効果がある。
【００３８】
請求項２の発明は、建物において室内外を仕切るガラス板に取り付けられるハウジングと、前記ハウジングに接着剤で固定されて前記ガラス板の振動を電圧信号に変換する圧電素子と、警報閾値よりも前記圧電素子の出力信号の振幅が大きければ警報を出力する報知手段とを備え、前記ハウジングは、前記圧電素子の接着面を囲むように前記圧電素子の周囲に立設した壁を有するので、周囲環境の温度変化による圧電素子の接着面の変形は少なく、圧電素子の破損を防止することができるという効果がある。
【００３９】
請求項３の発明は、請求項１または２において、前記ハウジングは、前記圧電素子が接着される箇所に、前記圧電素子を載置して予め定めた接着剤層の厚みに相当する同一高さの複数の凸部を備え、前記複数の凸部は、載置される前記圧電素子が前記ハウジングに対する平行度を維持できる箇所に各々配置されるので、ハウジングの寸法管理によって接着剤層の厚みを一定とすることで、センサの振動検出感度のバラツキを小さくして一定の範囲内に収めることができるという効果がある。
【００４０】
請求項４の発明は、請求項１または２において、前記ハウジングは、前記圧電素子が接着される箇所に、前記圧電素子の接着面の周縁部を載置する台部と、前記台部の内側に形成されて予め定めた接着剤層の厚みに相当する一定深さの凹部とを備え、前記台部は、載置された前記圧電素子が前記ハウジングに対する平行度を維持できる形状に形成されるので、ハウジングの寸法管理によって接着剤層の厚みを一定とすることで、センサの振動検出感度のバラツキを小さくして一定の範囲内に収めることができるという効果がある。
【００４１】
請求項５の発明は、請求項１乃至４いずれかにおいて、前記圧電素子は、接着面と該接着面に対向する面とに各々電極を設け、外面の少なくとも一部を前記電極の対向方向に段差を設けた階段形状としたので、圧電素子の感度を低下させることなく容易に電極を取り出すことができるという効果がある。
【００４２】
請求項６の発明は、請求項１乃至４いずれかにおいて、前記圧電素子は、接着面と該接着面に対向する面とに各々電極を設け、前記電極間の絶縁距離は前記電極の対向方向の厚みの少なくとも一部を含むので、圧電素子の感度を低下させることなく電極間の絶縁距離をとることができるという効果がある。
【図面の簡単な説明】
【図１】（ａ）本発明の実施形態１のガラス破壊センサを示す外観構成図である。
（ｂ）同上の回路構成図である
【図２】同上の圧電素子近傍の斜視図である。
【図３】同上の圧電素子近傍の側面図である。
【図４】同上の各種接着剤に対する熱衝撃試験の結果を示す図である。
【図５】本発明の実施形態２の圧電素子近傍の斜視図である。
【図６】同上のハウジングの変形を示す側面断面図である。
【図７】（ａ）本発明の実施形態３の第１の圧電素子近傍の表面図である。
（ｂ）同上の第１の圧電素子近傍の側面断面図である。
【図８】同上の第２の圧電素子近傍の表面図である。
【図９】同上の第３の圧電素子近傍の表面図である。
【図１０】（ａ）本発明の実施形態４の圧電素子近傍の表面図である。
（ｂ）同上の圧電素子近傍の断面図である。
【図１１】本発明の実施形態５の第１の圧電素子の構成を示す図である。
【図１２】同上の第１の圧電素子の斜視図である。
【図１３】同上の第２の圧電素子の構成を示す図である。
【図１４】同上の第２の圧電素子の斜視図である。
【図１５】同上の第３の圧電素子の斜視図である。
【図１６】本発明の実施形態６の圧電素子の構成を示す図である。
【図１７】同上の圧電素子の斜視図である。
【図１８】従来例の圧電素子とハウジングとの接着を示す図である。
【図１９】同上のハウジングの変形を示す側面図である。
【符号の説明】
１ハウジング
２圧電素子
３接着剤
Ｇガラス
Ｓ１ハイパスフィルタ回路
Ｓ２比較判断部
Ｓ３警報出力部
Ｖｔｈ警報閾値電圧[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a glass break sensor that is attached to a glass plate that partitions indoors and outdoors and detects breakage of the glass plate.
[0002]
[Prior art]
Conventionally, it is attached to a glass plate that separates the interior and exterior such as window glass and glass doors, and when a person trying to enter the room (hereinafter, an intruder) breaks the glass plate, it detects this and reports by sound or light. A glass breakage sensor for security is provided. This type of glass breakage sensor uses a piezoelectric element that converts the vibration of a glass sheet into a voltage signal as a vibration detecting means, and outputs an alarm if the amplitude of the output signal of the piezoelectric element is larger than an alarm threshold. As shown in FIGS. 2 and 3, when the housing 1 that forms the outer shell of the glass breakage sensor and is attached to the glass plate is a molded product, the disk-shaped piezoelectric element 2 is attached to the housing 1 with an adhesive 3. Was.
[0003]
When the piezoelectric element 2 is fixed to the housing 1 using the adhesive 3, as shown in FIG. 18, the amount of the adhesive 3 applied and the load applied to the piezoelectric element 2 at the time of curing are controlled to control the adhesive layer. The thickness was controlled.
[0004]
Alternatively, a concave portion is provided on the bonding surface of the housing to form an adhesive layer according to the depth of the concave portion, or a convex portion is provided on the bonding surface of the housing, and an adhesive layer corresponding to the height of the convex portion is formed. For example, the thickness of the adhesive layer was controlled. (For example, refer to Patent Document 1.)
Further, as shown in FIG. 2, the piezoelectric element 2 has electrodes 21 formed on the bonding surface (back surface) with the housing 1 and the surface (front surface) facing the bonding surface, respectively. In this case, in order to extract a signal from the electrode 21 on the back surface adhered to the housing 1, an electrode pattern of the folded electrode 22 extended from the electrode 21 on the back side of the piezoelectric element 2 to the side surface and drawn to the surface side of the piezoelectric element 2 is formed. ing. The electrode 21 on the front surface and the folded electrode 22 are each electrically connected to the circuit unit via the electric wire 5.
[0005]
[Patent Document 1]
JP-A-6-61276 (page 2, left column, lines 24 to 27, page 2, right column, lines 19 to 48, FIGS. 1 to 4)
[0006]
[Problems to be solved by the invention]
However, in the above-described conventional glass breakage sensor, an epoxy adhesive or the like having high hardness is used as the adhesive 3, and when the piezoelectric element 2 is attached to the molded housing 1, as shown in FIG. Due to the temperature change, the housing 1 is deformed as shown by the broken line in the figure, and the distortion (for example, the Y1, Y2 directions perpendicular to the bonding surface) is transmitted to the piezoelectric element 2 via the adhesive 3, and the housing 1 and the adhesive Due to the difference in linear expansion coefficient between the piezoelectric element 2 and the piezoelectric element 2, the piezoelectric element 2 cannot follow the deformation of the housing 1 and is damaged.
[0007]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a glass breakage sensor that prevents breakage of a piezoelectric element due to a temperature change in an ambient environment.
[0008]
[Means for Solving the Problems]
The invention according to claim 1 is a housing attached to a glass plate that partitions indoors and outdoors in a building; a piezoelectric element fixed to the housing with an adhesive to convert vibration of the glass plate into a voltage signal; A notifying means for outputting an alarm if the amplitude of the output signal of the piezoelectric element is large, wherein the hardness of the adhesive after curing is 40 or less in Shore hardness A.
[0009]
The invention according to claim 2 is a housing that is attached to a glass plate that partitions indoors and outdoors in a building, a piezoelectric element that is fixed to the housing with an adhesive and converts the vibration of the glass plate into a voltage signal, Notifying means for outputting an alarm if the amplitude of the output signal of the piezoelectric element is large, wherein the housing has a wall standing around the piezoelectric element so as to surround the bonding surface of the piezoelectric element. I do.
[0010]
According to a third aspect of the present invention, in the first or second aspect, the housing has the same height corresponding to a predetermined thickness of an adhesive layer on which the piezoelectric element is mounted at a position where the piezoelectric element is bonded. Wherein the plurality of projections are arranged at locations where the mounted piezoelectric element can maintain parallelism with respect to the housing.
[0011]
According to a fourth aspect of the present invention, in the first or second aspect, the housing has a base on which a peripheral portion of the bonding surface of the piezoelectric element is placed at a position where the piezoelectric element is bonded, and an inner side of the base. And a recess having a constant depth corresponding to a predetermined thickness of the adhesive layer. The base is formed in a shape that allows the mounted piezoelectric element to maintain parallelism with the housing. It is characterized by the following.
[0012]
According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the piezoelectric element is provided with an electrode on each of an adhesion surface and a surface facing the adhesion surface, and at least a part of an outer surface is arranged in a direction facing the electrode. It is characterized by having a staircase shape with a step.
[0013]
According to a sixth aspect of the present invention, in any one of the first to fourth aspects, the piezoelectric element is provided with electrodes on a bonding surface and a surface facing the bonding surface, and an insulation distance between the electrodes is in a direction facing the electrodes. Characterized in that it includes at least a part of the thickness of.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0015]
(Embodiment 1)
As shown in FIG. 1A, the glass breakage sensor of this embodiment is fixed in a housing 1 of a molded product attached to a glass plate G by a double-sided adhesive sheet and converts the vibration of the glass plate G into a voltage signal. It has a plate-shaped piezoelectric element 2 and outputs an alarm if the amplitude of the output signal of the piezoelectric element 2 is larger than the alarm threshold. The circuit configuration of the piezoelectric element 2 is as shown in FIG. 2, a high-pass filter circuit S1 having a cut-off frequency set to such an extent that a frequency relating to the destruction of the glass plate G in the output signal of the piezoelectric element 2 passes and noise is removed, and a high-pass filter circuit S1. The comparison and judgment unit S2 that compares the output of the filter circuit S1 with the alarm threshold voltage Vth, and the judgment result of the comparison and judgment unit S2 indicates that the output of the high-pass filter circuit S1 is larger than the alarm threshold voltage Vth. Consists alarm output Portion S3 Prefecture for issuing an alarm if Re.
[0016]
The piezoelectric element 2 is attached to the housing 1 with an adhesive 3 as shown in FIGS. 2 and 3, and the electrodes 21 and the folded electrodes 22 on the surface are each connected to the piezoelectric element 2 via the electric wire 5 as shown in FIG. Are electrically connected to the circuit section shown in FIG.
[0017]
The present embodiment differs from the conventional example in that the adhesive 3 has a Shore hardness A = 40 or less, for example, a silicon-based adhesive.
[0018]
Next, with respect to a sample in which the piezoelectric element 2 was adhered to the molded product housing 1 with adhesives 3 having different hardnesses, a thermal test was performed to confirm whether or not the piezoelectric element 2 was damaged with respect to a change in ambient temperature. The presence or absence of damage was confirmed by an impact test. As samples, adhesive 3a: Shore-hardness D = 89 (Shore-hardness A = 90 or more), adhesive 3b: Shore-hardness D = 75 (Shore-hardness A = 90 or more), adhesive 3c: Shore-hardness Four types of D = 40 (Shore-hardness A = 90) and adhesive 3d: Shore-hardness A = 40 were prepared. The test conditions were -40 ° C. to 80 ° C., which is 25 ° C. extended on both the low-temperature side and the high-temperature side with respect to the operating temperature range, and were strict conditions of 50 cycles.
[0019]
As shown in FIG. 4, the results of the thermal shock test indicate that the sample using the adhesives 3 a and 3 b is such that the piezoelectric element 2 is divided into two in the thickness direction, and the sample using the adhesive 3 c is a part of the sample. Was damaged or the sensitivity was degraded due to peeling of the electrode portion. However, the sample using the adhesive 3d was not damaged or deteriorated in sensitivity. Therefore, in the present embodiment, by using the adhesive 3 having a Shore hardness A = 40 or less, the adhesive 3 between the housing 1 and the piezoelectric element 2 absorbs expansion and contraction due to the difference in the respective linear expansion coefficients. Thus, the breakage of the piezoelectric element 2 can be eliminated.
[0020]
(Embodiment 2)
The basic configuration of the glass breakage sensor of the present embodiment is substantially the same as that of the first embodiment, and the same components are denoted by the same reference numerals and description thereof is omitted. FIGS. 5 and 6 show the bonding portion between the housing 1 and the disk-shaped piezoelectric element 2 of the present embodiment. The housing 1 extends along the outer periphery of the piezoelectric element 2 so as to surround the bonding surface of the piezoelectric element 2. The upright annular wall 10 is integrally formed. Since the piezoelectric element 2 is attached to the housing 1 with the adhesive 3 inside the integrally formed wall 10, even if the housing 1 is deformed as indicated by a broken line in FIG. Due to the rigidity, deformation (warpage) of the bonding surface can be suppressed, and the expansion and contraction force acting in the X1 and X2 directions parallel to the bonding surface is also greatly reduced.
[0021]
Therefore, the deformation of the bonding surface of the piezoelectric element 2 is small, and the distortion is not transmitted to the piezoelectric element 2, so that the piezoelectric element 2 is not damaged even if the adhesive 3 having high hardness is used. The planar shape of the wall 10 in FIGS. 5 and 6 is a circle, but any shape, such as a rectangle, can be used as long as it can surround the piezoelectric element.
[0022]
(Embodiment 3)
FIGS. 7A and 7B show a bonding portion between the housing 1 and the disc-shaped piezoelectric element 2 of the present embodiment, and the other configuration is the same as that of the first or second embodiment. Are denoted by the same reference numerals and description thereof is omitted. A circular concave portion 12 is formed in a portion of the housing 1 to which the piezoelectric element 2 is adhered, and the convex portion 11a whose height matches the predetermined thickness T1 of the adhesive layer is formed on the bottom surface of the concave portion 12. To 11c are arranged at three places. The protrusions 11a to 11c are arranged concentrically such that the centers of the protrusions are spaced 120 ° from the center of the circular bonding surface of the piezoelectric element 2, and the piezoelectric element 2 is mounted on the protrusions 11a to 11c. To maintain the parallelism with respect to the housing 1.
[0023]
Here, conventionally, when the piezoelectric element 2 is fixed to the housing 1 using the adhesive 3 as shown in FIG. 18, there is a problem that it is difficult to control the thickness of the adhesive layer after curing, and the vibration detection sensitivity of the sensor varies. Was. However, when the adhesive 3 is applied to the bonding portion of the piezoelectric element 2 as in the present embodiment, and the piezoelectric element 2 is placed on the protrusions 11a to 11c and the adhesive 3 is cured, the thickness T1 of the adhesive layer becomes Since the height of the projections 11a to 11c is determined, the thickness of the vibration transmission path (the thickness T1 of the adhesive layer) is constant, and the variation in the vibration detection sensitivity of the sensor is reduced and falls within a certain range.
[0024]
Instead of the convex portions 11a to 11c, an annular convex portion 13 shown in FIG. 8 or a pair of linear convex portions 14a and 14b shown in FIG. Any material can be used as long as the thickness T1 of the agent layer and the parallelism of the piezoelectric element 2 to the housing 1 can be maintained.
[0025]
(Embodiment 4)
FIGS. 10A and 10B show an adhesive portion between the housing 1 and the disc-shaped piezoelectric element 2 of the present embodiment, and the other configuration is the same as that of the first or second embodiment. Are denoted by the same reference numerals and description thereof is omitted. A circular concave portion 12 is formed in a portion of the housing 1 to which the piezoelectric element 2 is adhered, and the circular concave portion 12 has a diameter smaller than that of the concave portion 12 and a depth corresponding to a predetermined thickness T1 of the adhesive layer. Is formed on the bottom surface of the concave portion 12. The piezoelectric element 2 is mounted on the circumferential portion (base) of the concave portion 12 at the peripheral edge of the bonding surface to maintain parallelism with the housing 1.
[0026]
Here, conventionally, when the piezoelectric element 2 is fixed to the housing 1 using the adhesive 3 as shown in FIG. 18, there is a problem that it is difficult to control the thickness of the adhesive layer after curing, and the vibration detection sensitivity of the sensor varies. Was. However, when the adhesive 3 is applied to the bonding portion of the piezoelectric element 2 as in the present embodiment, and the piezoelectric element 2 is placed on the circumferential portion of the concave portion 12 and the adhesive 3 is cured, the thickness T1 of the adhesive layer is increased. Is determined by the depth of the concave portion 15, the thickness of the vibration transmission path (thickness T1 of the adhesive layer) becomes constant, and the variation in the vibration detection sensitivity of the sensor becomes small and falls within a certain range.
[0027]
The shape of the recess 15 may be any shape such as a square, as long as the thickness T1 of the adhesive layer and the parallelism of the piezoelectric element 2 to the housing 1 can be maintained.
[0028]
(Embodiment 5)
FIGS. 11 and 12 show a piezoelectric element 2 according to this embodiment. Other configurations are the same as those in any one of the first to fourth embodiments. The same components are denoted by the same reference numerals and description thereof is omitted. The piezoelectric element 2 of the present embodiment has a two-stage configuration in which disc-shaped element portions 2a and 2b having different diameters are overlapped while one side end portions thereof are aligned with each other, and the back surface of the element portion 2a having a small diameter. Is an adhesive surface with the non-metallic housing 1, and the electrode 21 is formed on the entire surface. Another electrode 21 having the same diameter as the element portion 2a is also formed on the surface of the element portion 2b. Here, the diameter of each electrode 21 on the front and back surfaces of the piezoelectric element 2 is a diameter R1 determined by the detection frequency in order to secure sensitivity at the detection frequency.
[0029]
An extension electrode 23 extending from the electrode 21 on the back surface of the element portion 2a to the side surface of the element portion 2a, the back surface and the side surface of the element portion 2b is formed, and an electric wire is previously soldered to the extension electrode 23 on the back surface of the element portion 2b. After attaching, it is attached to the housing 1 and wired to the circuit section. The other electrode 21 formed on the surface of the element section 2b is also wired to the circuit section.
[0030]
Here, conventionally, when manufacturing the piezoelectric element 2 having the electrode pattern of the folded electrode 22 as shown in FIG. 2, in order to secure an insulation distance between the two electrodes when the ceramic is polarized, the thickness of the piezoelectric element 2 is equivalent to the thickness. Since it is necessary to increase the distance, there is a problem that the sensitivity is lower than that of the electrode pattern on both surfaces.
[0031]
However, in the present embodiment, since the thickness direction of the piezoelectric element 2 is formed in a stepwise manner, the insulation distance Z1 between the electrodes 21 on the front and back surfaces can be sufficiently ensured, and at the same time, the diameter R1 of the electrode 21 determined by the detection frequency. Are polarized, the sensitivity is improved as compared with the conventional folded electrode pattern. Note that the extension electrode 23 on the side surface of the element portion 2b may not be provided.
[0032]
Also, as shown in FIGS. 13 and 14, the same effect can be obtained by a two-stage configuration in which the centers of the disc-shaped element portions 2a and 2b having different diameters are overlapped with each other. 13 and 14, there is no extension electrode 23 on the side surface of the element portion 2b, and the insulation distance Z2 between the electrodes 21 on the front and back surfaces is equal to the insulation distance Z1 when the extension electrode 23 on the side surface of the element portion 2b exists. The insulation distance can be increased by the thickness of the portion 2b.
[0033]
Further, in the present embodiment, the shape in the thickness direction of the piezoelectric element 2 is stepped, but as shown in FIG. 15, the side surface of the element portion 2b may be formed in a slope shape whose diameter decreases as approaching the surface. No problem.
[0034]
(Embodiment 6)
FIGS. 16 and 17 show the piezoelectric element 2 of the present embodiment. The other configuration is the same as that of any one of the first to fourth embodiments, and the same components are denoted by the same reference numerals and description thereof is omitted. The piezoelectric element 2 of the present embodiment has a three-stage configuration in which a disc-shaped element part 2e having a diameter larger than the element parts 2e and 2f is interposed between disc-shaped element parts 2d and 2f having the same diameter. The electrode 21 is formed on the entire surface of the front surface of the element portion 2d and the back surface of the element portion 2f, and the back surface of the element portion 2f is an adhesive surface with the non-metal housing 1. Here, the diameter of each electrode 21 on the front and back surfaces of the piezoelectric element 2 is a diameter R1 determined by the detection frequency in order to secure sensitivity at the detection frequency.
[0035]
The extension electrode 23 extends from the electrode 21 on the surface of the element 2d to the side of the element 2d, the surface of the element 2e, and the electrode 21 on the back of the element 2f to the side of the element 2f and the back of the element 2e. The extension electrodes 23 extending up to are formed, and an electric wire is soldered in advance to the extension electrodes 23 on the back surface of the element portion 2f, and then is attached to the housing 1 and wired to the circuit portion. The other electrode 21 formed on the surface of the element section 2b is also wired to the circuit section.
[0036]
In the present embodiment, the thickness of the element portion 2e is set to the insulation distance Z3 between the electrodes 21 on the front and back surfaces, and the insulation distance can be sufficiently secured, and at the same time, all the portions of the diameter R1 of the electrode 21 determined by the detection frequency are polarized. Therefore, the sensitivity is improved as compared with the conventional folded electrode pattern. Furthermore, since the structure is more symmetrical than in the fifth embodiment, spurious can be suppressed.
[0037]
【The invention's effect】
The invention according to claim 1 is a housing attached to a glass plate that partitions indoors and outdoors in a building; a piezoelectric element fixed to the housing with an adhesive to convert vibration of the glass plate into a voltage signal; A notifying means for outputting an alarm if the amplitude of the output signal of the piezoelectric element is large; and the adhesive has a hardness of 40 or less in Shore-Hardness A after curing, so that the adhesive is bonded between the housing and the piezoelectric element. There is an effect that the agent absorbs expansion and contraction due to the difference in the coefficient of linear expansion, and can prevent breakage of the piezoelectric element due to a temperature change in the surrounding environment.
[0038]
The invention according to claim 2 is a housing that is attached to a glass plate that partitions indoors and outdoors in a building, a piezoelectric element that is fixed to the housing with an adhesive and converts the vibration of the glass plate into a voltage signal, Notification means for outputting an alarm if the amplitude of the output signal of the piezoelectric element is large; and the housing has a wall standing upright around the piezoelectric element so as to surround the bonding surface of the piezoelectric element. The deformation of the bonding surface of the piezoelectric element due to the temperature change is small, and there is an effect that breakage of the piezoelectric element can be prevented.
[0039]
According to a third aspect of the present invention, in the first or second aspect, the housing has the same height corresponding to a predetermined thickness of an adhesive layer on which the piezoelectric element is mounted at a position where the piezoelectric element is bonded. The plurality of protrusions are provided, and the plurality of protrusions are arranged at locations where the mounted piezoelectric element can maintain parallelism with respect to the housing, so that the thickness of the adhesive layer is controlled by dimensional management of the housing. By making it constant, there is an effect that the variation of the vibration detection sensitivity of the sensor can be reduced and kept within a certain range.
[0040]
According to a fourth aspect of the present invention, in the first or second aspect, the housing has a base on which a peripheral portion of the bonding surface of the piezoelectric element is placed at a position where the piezoelectric element is bonded, and an inner side of the base. And a recess having a constant depth corresponding to a predetermined thickness of the adhesive layer. The base is formed in a shape that allows the mounted piezoelectric element to maintain parallelism with the housing. Therefore, by keeping the thickness of the adhesive layer constant by controlling the dimensions of the housing, there is an effect that the variation in the vibration detection sensitivity of the sensor can be reduced and kept within a certain range.
[0041]
According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the piezoelectric element is provided with an electrode on each of an adhesion surface and a surface facing the adhesion surface, and at least a part of an outer surface is arranged in a direction facing the electrode. Since the stepped shape is provided with a step, there is an effect that the electrode can be easily taken out without lowering the sensitivity of the piezoelectric element.
[0042]
According to a sixth aspect of the present invention, in any one of the first to fourth aspects, the piezoelectric element is provided with electrodes on a bonding surface and a surface facing the bonding surface, and an insulation distance between the electrodes is in a direction in which the electrodes face each other. Since at least a part of the thickness of the piezoelectric element is included, the insulating distance between the electrodes can be increased without lowering the sensitivity of the piezoelectric element.
[Brief description of the drawings]
FIG. 1A is an external configuration diagram illustrating a glass breakage sensor according to a first embodiment of the present invention.
(B) It is a circuit configuration diagram of the same. [FIG. 2] It is a perspective view near the piezoelectric element of the same.
FIG. 3 is a side view showing the vicinity of the piezoelectric element according to the first embodiment;
FIG. 4 is a view showing the results of a thermal shock test on various adhesives according to the first embodiment.
FIG. 5 is a perspective view of the vicinity of a piezoelectric element according to a second embodiment of the present invention.
FIG. 6 is a side sectional view showing a modification of the housing.
FIG. 7A is a front view of the vicinity of a first piezoelectric element according to a third embodiment of the present invention.
FIG. 3B is a side cross-sectional view showing the vicinity of the first piezoelectric element in the first embodiment.
FIG. 8 is a surface view of the vicinity of the second piezoelectric element of the above.
FIG. 9 is a front view showing the vicinity of a third piezoelectric element of the above.
FIG. 10A is a front view of the vicinity of a piezoelectric element according to a fourth embodiment of the present invention.
(B) It is sectional drawing near a piezoelectric element same as the above.
FIG. 11 is a diagram illustrating a configuration of a first piezoelectric element according to a fifth embodiment of the present invention.
FIG. 12 is a perspective view of the first piezoelectric element of the above.
FIG. 13 is a diagram showing a configuration of a second piezoelectric element of the above.
FIG. 14 is a perspective view of a second piezoelectric element of the above.
FIG. 15 is a perspective view of a third piezoelectric element of the above.
FIG. 16 is a diagram illustrating a configuration of a piezoelectric element according to a sixth embodiment of the present invention.
FIG. 17 is a perspective view of the above piezoelectric element.
FIG. 18 is a diagram showing adhesion between a piezoelectric element and a housing in a conventional example.
FIG. 19 is a side view showing a modification of the above housing.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Housing 2 Piezoelectric element 3 Adhesive G Glass S1 High pass filter circuit S2 Comparison judgment part S3 Alarm output part Vth Alarm threshold voltage

Claims

A housing attached to a glass plate partitioning the interior and exterior of the building, a piezoelectric element fixed to the housing with an adhesive to convert vibration of the glass plate into a voltage signal, and an amplitude of an output signal of the piezoelectric element from an alarm threshold And a notifying means for outputting an alarm if is large, wherein the hardness of the adhesive after curing is 40 or less in Shore-Hardness A.

A housing attached to a glass plate partitioning the interior and exterior of the building, a piezoelectric element fixed to the housing with an adhesive to convert vibration of the glass plate into a voltage signal, and an amplitude of an output signal of the piezoelectric element from an alarm threshold Alarm means for outputting an alarm if the size is larger, wherein the housing has a wall standing upright around the piezoelectric element so as to surround the bonding surface of the piezoelectric element.

The housing includes a plurality of protrusions having the same height corresponding to a predetermined thickness of an adhesive layer on which the piezoelectric element is mounted, where the piezoelectric element is bonded, and the plurality of protrusions are The glass breakage sensor according to claim 1, wherein the mounted piezoelectric elements are arranged at locations where parallelism with respect to the housing can be maintained.

The housing has a base on which the peripheral surface of the bonding surface of the piezoelectric element is placed at a position where the piezoelectric element is bonded, and a thickness corresponding to a predetermined adhesive layer formed inside the base. 3. The glass breakage according to claim 1, further comprising a concave portion having a constant depth, wherein the base portion is formed in a shape such that the mounted piezoelectric element can maintain parallelism with the housing. 4. Sensors.

2. The piezoelectric element according to claim 1, wherein an electrode is provided on each of an adhesive surface and a surface facing the adhesive surface, and at least a part of the outer surface has a stepped shape in which a step is provided in a direction facing the electrode. 5. The glass breakage sensor according to any one of claims 4 to 4.

2. The piezoelectric element according to claim 1, wherein electrodes are provided on an adhesive surface and a surface facing the adhesive surface, respectively, and an insulation distance between the electrodes includes at least a part of a thickness of the electrodes in a facing direction. 5. The glass breakage sensor according to any one of claims 4 to 4.