JP4302857B2

JP4302857B2 - Piezoelectric sounder

Info

Publication number: JP4302857B2
Application number: JP2000143162A
Authority: JP
Inventors: 昇三西山
Original assignee: Hokuriku Electric Industry Co Ltd
Current assignee: Hokuriku Electric Industry Co Ltd
Priority date: 2000-05-16
Filing date: 2000-05-16
Publication date: 2009-07-29
Anticipated expiration: 2020-05-16
Also published as: JP2001326997A

Description

【０００１】
【発明が属する技術分野】
本発明は、矩形状の圧電素子を用いた圧電発音器に関するものである。
【０００２】
【従来の技術】
矩形状の圧電素子を用いる圧電発音器も、既存の圧電発音器と同様に、圧電振動子とこの圧電振動子を支持する振動子支持構造とを備えている。圧電振動子は、矩形状の圧電素子と、この圧電素子の表面上に接合された表面電極と、圧電素子の裏面上に接合された裏面電極とを有している。そしてこの圧電振動子は、ケース内に配置されて、ケースの内部で圧電振動子の表面側に位置する音響空間と裏面側に位置する音響空間とが連通しないように振動子支持構造によって気密に支持されている。このような構造を備えた圧電発音器としては、例えば特開平１１−３５５８９０号公報、特開平９−２７１０９６号公報等に開示されたものがある。
【０００３】
特開平１１−３５５８９０号公報に開示された圧電発音器は、圧電振動子の長手方向の両端部が、導電性の支持部材を用いて固定され、圧電振動子の長手方向に沿う一対の縁部が、圧電振動子の裏面側に形成されている音響空間で発生した音が圧電振動子の表面側に形成されている音響空間に回り込まないように、可撓性を有するシリコーンゴム等で封止されている。
【０００４】
また特開平９−２７１０９６号公報に開示された圧電発音器は、矩形状の窓部を有する樹脂板の窓部の周縁部に、ダイアフラムに矩形状の圧電素子が接合されなる圧電振動子のダイアフラムの外周部を貼り合わせ、この樹脂板の長手方向に沿う一対の長辺を一対の支持体（振動子支持構造）で支持した構造を有している。
【０００５】
【発明が解決しようとする課題】
しかしながらこれらの構造では、圧電振動子を固定するための接着剤と音響空間を分離するための接着剤との２種類の接着剤が必要となる。このため、製造工程で各接着剤の塗布工程が必要であり、接着剤の硬化時間が必要となるため、製造時間が増加して生産効率が悪かった。
【０００６】
また従来の構造では、圧電振動子と端子部との電気的な接続に被覆リード線を用い、被覆リード線の導体部を圧電振動子の電極部に半田付けにより接合していた。しかしながら被覆リード線を半田付けする作業は、作業性が悪く、自動化が非常に困難であった。また半田付けで用いるコテの先端温度は、２５０〜３５０℃と高く、このような高い温度が圧電素子に加わると圧電素子にクラックを発生させるおそれがある。また圧電素子に急激な温度差を与えると、圧電性が消失する危険性がある。また被覆リード線に代えてバネ性金属端子を用いて、接触だけで電気的な接続を図ることも考えられる。しかしながらこのようなバネ性金属端子を小型のケース内に配置することは設計が難しく、ケースの厚みを厚くする必要があるために、薄型化に難しい問題が生じる。
【０００７】
本発明の目的は、製造が容易な圧電発音器を提供することにある。
【０００８】
本発明の目的は、圧電素子の圧電性を消失させることなく、製造できる圧電発音器を提供することにある。
【０００９】
本発明の目的は、薄型化を図ることができる圧電発音器を提供することにある。
【００１０】
本発明の他の目的は、表面実装化が容易な圧電発音器を提供することにある。
【００１１】
本発明の他の目的は、音圧が高い圧電発音器を提供することにある。
【００１２】
本発明の他の目的は、量産性に優れた圧電発音器を提供することにある。
【００１３】
【課題を解決するための手段】
本発明は、矩形状の圧電素子、圧電素子の表面上に接合された表面電極及び圧電素子の裏面上に接合された裏面電極を有する圧電振動子と、圧電振動子の表面側に位置する音響空間と裏面側に位置する音響空間とを連通させないようにして圧電振動子を支持する振動子支持構造とを具備する圧電発音器を改良の対象とする。本発明で用いる振動子支持構造は、絶縁材料によって形成された可撓性を有するシート部材と、シート部材の外周部が接合される枠状部分を有するベース部材とを有する。シート部材としては、例えばポリイミドやポリエチレンテレフタレート（ＰＥＴ）等の絶縁性を有する合成樹脂シートを用いることができる。そして本発明では、このシート部材の表面上には、圧電振動子の裏面電極と電気的接続される部分と該部分に接続された第１の入力電極とが一体になった第１の導電体が接合されており、またこのシート部材には表面電極が電気的に接続される第２の入力電極を構成する第２の導電体も接合されている。これらの導電体は、銅箔等の金属箔により形成することができる。またメッキ、スパッタリング等によりこれらの導電体を形成することもできる。更にこれらの導電体を銀レジンペーストなどの導電性レジンペーストを用いて形成することもできる。
【００１４】
本発明においては、圧電振動子の表面電極と第２の導電体とに跨って導電性レジンペーストを塗布し且つこれを硬化して形成した電極接続用導電性接続部により、表面電極と第２の導電体とを接続する。可撓性を有するシート部材は、その撓み性から圧電振動子の振動を阻害することはない。このようにすると、リード線や端子金具を用いた接合に比べ、圧電発音器の全体の厚み寸法を薄くすることができる。またリード線や半田を用いないので、製造の自動化が容易になり、半田付け時の熱により圧電素子の圧電性が消失するのを防ぐことができる。
【００１５】
また、本発明の圧電発音器のより具体的な態様では、矩形状の圧電素子、圧電素子の表面上に接合された表面電極及び圧電素子の裏面上に接合された裏面電極を有する圧電振動子と、圧電振動子の表面側に位置する音響空間と裏面側に位置する音響空間とを連通させないようにして圧電振動子を支持する振動子支持構造とを具備する。そして振動子支持構造を、絶縁樹脂材料によって形成された可撓性を有するシート部材と、シート部材の裏面の外周部が接合される枠状部分及び枠状部分によって囲まれて圧電振動子の振動を許容する凹部または窓部を備えた絶縁材料からなるベース部材とから構成する。この場合も、シート部材の表面上には、圧電振動子の裏面電極と電気的接続される部分と該部分に接続された第１の入力電極とが一体になった第１の導電体と、表面電極が電気的に接続される第２の入力電極を構成する第２の導電体とを接合し、表面電極と第２の導電体とを、導電性レジンペーストを両者に跨って塗布し且つこれを硬化して形成した電極接続用導電性接続部により接続する。
【００１６】
ベース部材の枠状部分とシート部材の裏面とを接合する場合は、接着剤により接合してもよい。またベース部材の少なくとも枠状部分及びシート部材を溶着可能な合成樹脂材料により形成する場合は、シート部材と枠状部分とを熱溶着または超音波振動溶着により接合すればよい。
【００１７】
第１及び第２の導電体を金属箔により形成する場合において、第１の導電体の端面が第２の導電体側に露出しているような場合には、電極接続用導電性接続部の下に導電性接続部と第１の導電体との短絡を阻止する絶縁性樹脂からなる絶縁層を形成するのが好ましい。なお第１の導電体の裏面電極を構成する部分に、第１の導電体と接触しないようにして第２の導電体が部分的に入り込む導電体受け入れ凹部を形成し、電極接続用導電性接続部が表面電極と導電体受け入れ凹部の外側に位置する第２の導電体間に直接形成するようにすれば、導電性接続部と第１の導電体との短絡防止のために形成する絶縁層を設ける必要がなくなり、製造工程を少なくできて、製品の価格を下げることが可能になる。
【００１８】
シート部材が薄くなればなるほど、ベース部材にシート部材を接合する場合に、シート部材にはしわ等が発生し、接合し難くなる場合がある。このようなときは、シート部材の表面に、シート部材の外縁部に沿い且つ第１及び第２の導電体と電気的に接続しないように補強用導電体を形成すればよい。なお第１及び第２の導電体並びに補強用導電体は金属箔により形成することができる。この場合、補強用導電体は第１の導電体または第２の導電体の一方と連結されていても問題はない。
【００１９】
さらに第１の導電体と補強用導電体との間に位置するシート部材の部分を、圧電振動子の振動を許容するように蛇腹状に形成すれば、この部分の変形が容易になり、シート部材を用いる場合でも、圧電振動子を十分に振動させることができる。
【００２０】
表面実装型の圧電発音器を構成する場合には、ベース部材には、枠状部分にシート部材が接合された状態でシート部材の外側に位置する部分に、第１の入力電極及び第２の入力電極と電気的に接続される第１及び第２の実装用端子部を設ける。そして第１の入力電極及び第２の入力電極と第１及び第２の実装用端子部とを、導電性レジンペーストを両者に跨って塗布し且つこれを硬化して形成した端子接続用導電性接続部により接続する。このようにすれば、表面実装型の圧電発音器の実装用端子部と圧電振動子との電気的な接続を容易に行える上、表面実装型の圧電発音器の構造が簡単になる。
【００２１】
なお電極接続用導電性接続部と端子接続用導電性接続部とを一緒に形成すると、圧電発音器の製造工数を少なくすることができる。
【００２２】
また圧電振動子を覆うカバー部材をベース部材に固定し、このベース部材とカバー部材とによりケースを構成するのが好ましい。このようにすると、ベース部材がケースの一部を構成するため、部品点数が少なくなって、製造コストを下げることができる。
【００２３】
圧電発音器は、使用していないとき、温度差や衝撃により自発分極電荷が発生し、この電荷で圧電素子が電気的に破壊されるおそれがある。このような場合には、電極接続用導電性接続部と並列に振動時の圧電素子の抵抗値よりも大きな抵抗値を有する印刷抵抗体を設けておく。このようにすると圧電素子で発生した自発分極電荷はこの抵抗体を通して放電されるので、圧電素子が電気的に破壊されるのを防止することができる。
【００２４】
より高い音圧やより広い周波数帯域を得るためには、複数の圧電素子を併用することになる。このような複数の圧電素子を併用する場合には、複数の凹部または窓部を有するベース部材と、ベース部材に接合され且つ絶縁材料によって形成された可撓性を有するシート部材と、ベース部材の複数の凹部または窓部に対応するシート部材の複数の可撓領域の表面上に形成された複数の導電部分と、複数の導電部分の上に裏面電極が接合された複数の矩形状の圧電素子と、複数の圧電素子の表面にそれぞれ接合された複数の表面電極と、シート部材の表面に形成された第１及び第２の入力電極と、シート部材の表面に形成されて複数の導電部分と第１の入力電極とを電気的に接続する第１の接続パターンと、シート部材の複数の可撓領域の表面またはその近傍に形成された複数の接続用電極と、シート部材の表面に形成されて複数の接続用電極と第２の入力電極とを電気的に接続する第２の接続パターンと、導電性レジンペーストを複数の表面電極と複数の接続用電極とに跨って塗布し且つこれを硬化して形成して複数の表面電極と複数の接続用電極とをそれぞれ接続する複数の電極接続用導電性接続部と、ベース部材に対して取付けられ複数の圧電素子に個別に対応する複数の音響空間を形成する構造を備えたカバー部材とから圧電発音器を構成する。この場合、各圧電振動子の共振周波数と複数の音響空間のそれぞれの共振周波数を適当に選択することにより、１つの圧電振動子を用いる場合と比べて、圧電発音器の音圧を高くして、しかも周波数帯域を広げることができる。
【００２５】
【発明の実施の形態】
以下、図面を参照して本発明の実施の形態の一例を詳細に説明する。図１は本発明の第１の実施の形態の圧電発音器の構成を示す分解斜視図である。なお図１では、後述するカバー部材とベース部材と分離した状態を示している。図１において、符号１で示した部材は圧電振動子である。圧電振動子１は、ＰＴＺ等の圧電セラミックスよりなる矩形状の圧電素子３と、この圧電素子３の表面上に接合された表面電極５と、圧電素子３の裏面上に接合さた裏面電極７（図面上は示されていない。）とから構成されたユニモルフ型の圧電振動子である。表面電極５及び裏面電極７は、例えばガラスペーストに銀の粉末を混練してなる導電性ペーストを圧電素子３の両面に印刷し、これを焼成して形成する。圧電素子３には、表面電極５と裏面電極７との間に直流電圧を印加して予め分極処理が施されている。したがって表面電極５と裏面電極７との間に所定周期のパルス電圧が印加されると、圧電素子３はこの所定の周波数で振動する。
【００２６】
符号９は、圧電振動子１を支持する振動子支持構造を示している。振動子支持構造９は、シート部材１１とベース部材１３とから構成されている。シート部材１１は、矩形形状を有しており、ポリイミドやポリエチレンテレフタレート（ＰＥＴ）等の絶縁または合成樹脂材料からなる厚さ１０〜１００μｍの膜即ちシートでできており、電気的な絶縁性と機械的な可撓性とを備えている。シート部材１１の表面には、例えば銅箔等の金属箔、スパッタや蒸着により形成した薄膜導体（例えば１０〜２５０μｍ）の厚さを有する第１の導電体１５及び第２の導電体１７が形成されている。第１の導電体１５には、圧電素子３の裏面電極７と電気的に接続するように第１の入力電極１９が一体に設けられている。圧電素子３の裏面電極７は、レジン系の接着剤または導電性接着剤を用いて第１の導電体１５の接続部分に接続すればよい。第２の導電体１７は圧電素子３の表面電極５が接続される第２の入力電極を構成している。
【００２７】
圧電素子３の表面電極５と第２の導電体１７とは、電極接続用導電性接続部２３により電気的に接続されている。なお電極接続用導電性接続部２３の下部には、圧電素子３の表面と第２の導電体１７とに跨ってエポキシレジン等の絶縁樹脂材料ペーストを用いて絶縁層２１が形成されている。この絶縁層２１は、電極接続用導電性接続部２３が、第１の導電体１５と接触して短絡を発生するのを防止している。この電極接続用導電性接続部２３は、エポキシレジン等の有機材料に銀粉末，パラジウム粉末等の導電性粉末を混練した導電性レジンペーストから形成される。絶縁層２１を形成するためのエポキシレジン及び導電性レジンペーストは、通常１５０℃以下の温度で硬化できるため、硬化工程において、圧電素子３の圧電性が消失するようなことはない。
【００２８】
シート部材１１は、ベース部材１３の上に接合されている。ベース部材１３はＰＢＴ等のプラスチック絶縁部材により形成されている。ベース部材１３は、矩形の板状本体の表面に輪郭形状が矩形をなす枠状部材２５が一体になった構造を有している。枠状部分２５に囲まれた領域には、窓部または凹部２７が形成されている。この凹部２７は圧電振動子１の振動を許容する深さになっている。枠状部分２５の上面には、シート部材１１の裏面の外周部が接着剤や溶着技術等を用いて接合されている。ベース部材１３の長手方向の両端部には、枠状部材２５の外側に、表面実装用の半田付け用の端子部を構成する第１の実装用端子部２９及び第２の実装用端子部３１が設けられている。これらの実装用端子部２９及び３１は、ベース部材１３にインサート成形されている。第１の実装用端子部２９は第１の入力電極１９と図示しない端子接続用導電性接続部によって電気的に接続される。また第２の実装用端子部３１は、第２の入力電極を構成する第２の導電体１７と図示しない端子接続用導電性接続部によって電気的に接続される。これらの端子接続用導電性接続部は、前述の電極接続用導電性接続部２３と同様に、エポキシレジン等の有機材料に銀粉末，パラジウム粉末等の導電性粉末を混練した導電性レジンペーストから形成される。したがって前述の電極接続用導電性接続部２３を形成する際に、同時に第２の実装用端子部３１と第２の導電体１７とを接続する端子接続用導電性接続部とを同時に形成するようにしてもよい。
【００２９】
符号３３で示した部材は箱型のカバー部材であり、ベース部材１３に接着剤等により接合されている。カバー部材３３をベース部材１３に接合することにより圧電振動子１の前方側に音響空間（前気室）が形成されている。またシート部材１１によって塞がれた枠状部材２５によって囲まれた凹部２７内に圧電振動子１の後方側の音響空間（後気室）が形成されている。そして圧電振動子１が振動することによって発生した音はカバー部材３３の上部に設けられた発音孔３５から外部に放音される。
【００３０】
次に図１に示した圧電発音器の製造方法を製造工程順に説明する。図２（Ａ）乃至（Ｄ）は本発明の圧電発音器を製造する場合の製造工程を製造工程順に示したものである。まず、ＰＺＴ等の圧電セラミックスからなる圧電素子３の表面に表面電極５を形成し、圧電素子３の裏面に裏面電極７をそれぞれ形成する。次にシート部材１１の表面上に図２（Ａ）の圧電素子３の裏面電極７と電気的に接続する第１の導電体１５と、図２（Ａ）の圧電素子３の表面電極５と電気的に接続する第２の導電体１７とを形成する。
【００３１】
次に図２（Ｃ）に示すように、シート部材１１の表面上に形成した第１の導電体１５の上に圧電素子３の裏面電極７側をレジン系の接着剤または導電性接着剤を用いて貼り合わせる。そして、圧電素子３の表面電極５と第２の導電体１７とを電気的に接続する。接続の方法は、圧電素子３の側面を覆うように有機性の絶縁レジストを塗布して絶縁層２１を形成し、その上から表面電極５と第２の導電体１７とを跨ぐように有機銀からなる導電性のレジンペーストを印刷により塗布し、その後硬化させる。
【００３２】
次に図２（Ｄ）に示すように、図２（Ｃ）で表面上に圧電素子３を貼付けたシート部材１１の外周部を圧電発音器のベースとなるベース部材１３の枠状部分２５に接着剤や熱溶着等を用いて接合する。そして第１の入力電極１７と第１の実装用端子２９との間及び第２の入力電極１９と第２の実装用端子２９との間に，両者に跨るようにして導電性のレジンペーストを印刷により塗布し、その後硬化させて両者間を電気的接続する。最後に図１に示したケース部材３３をベース部材１３に接着剤や熱圧着等により接合させる。
【００３３】
図３は本発明の他の実施の形態で用いるシート部材１１１に圧電振動子１を接合する前の状態の斜視図である。なお、図３の実施の形態において、図１に示した実施の形態を構成する部分と同様の部分には、図１に付した符号と同じ符号を付して説明を省略する。この実施の形態では、圧電振動子１の裏面電極７と電気的に接続される第１の導電体１１５の接続部分に、第１の導電体１１５と接触しないようにして第２の導電体１１７が部分的に入り込むように導電体受け入れ凹部１１６が形成されている。そしてこの導電体受け入れ凹部１１６内に第２の導電体１１７の一部が入り込むようにして形成されている。これらの導電体が形成されたシート部材１１１を用いて、図１及び図２で示した電極接続用導電性接続部２３を表面電極５と導電体受け入れ凹部１１６の外側に位置する第２の導電体１１７間に直接形成するようにすれば、電極接続用導電性接続部２３と第１の導電体１１５との短絡防止のために形成する絶縁層２１を設ける必要がなくなり、製造工程を少なくすることができる。
【００３４】
図４は本発明の他の実施の形態で用いるシート部材２１１の平面図である。このシート部材２１１の表面上には第１の導電体２１５及び第２の導電体２１７が形成されている。そして第１の導電体２１５と第２の導電体２１７とを囲むようにして、シート部材２１１の外縁部に、第１の導電体２１５及び第２の導電体２１７を形成する金属箔と同じ金属箔からなる補強用導電体２５１，２５３が形成されている。この補強用導電体２５１，２５３を設ける理由は以下のとおりである。ベース部材にシート部材２１１を接合する際に、シート部材２１１が薄くなればなるほどシート部材にはしわ等が発生し、接合し難くなる。そこでこのような場合に、図４で示した補強用導電体２５１，２５３を設けてシート部材２１１の外周部の強度を高めると、シート部材２１１の外周部にしわが発生しなくなって、シート部材２１１とベース部材との接合をスムーズに行うことができる。なお、補強用導電体２５１，２５３は第１の導電体１１５あるいは第２の導電体１１７のうちどちらか一方と接続されていても何等問題はない。
【００３５】
図５は本発明の他の実施の形態を説明するために用いる断面図であり、この図は図４のＡ−Ａ線の位置で断面にした断面図である。図５に示したシート部材３１１には、シート部材２１１の第１の導電体２１５と補強用導電体２５１，２５３との間に位置するシート部材２１１の２箇所の部分３５０及び３６０に蛇腹状または波板状の加工が施されている。このような部分３５０及び３６０を設けると、これらの部分の変形が容易になり、圧電振動子を十分に振動させることができる。
【００３６】
図６は、上記の各実施の形態を大量生産する場合に用いる多連のシート部材連結体５５０の一部を示す図である。このシート部材連結体５５０は、ポリイミド等のフレキシブル基板に張られた金属箔にエッチングを施して形成されている。図示のシート部材連結体５５０の幅方向（長手方向と直交する方向）の両端部には、長手方向に所定の間隔をあけて送給用ガイド孔５６０…が形成されている。この送給用ガイド孔５６０…に図示しないガイドローラの外周部に設けられた突起が挿入されて、シート部材連結体５５０は長手方向に送給される。このようなシート部材連結体５５０に対して、圧電振動子を接合し、電極接続用導電性接続部を形成した後に、各シート部材を切り出して、ベース部材に接合される部品を製造すれば、大量生産が容易になる。
【００３７】
なお、上述した各実施の形態において、圧電振動子の表面電極とシート部材の表面上に形成した第１の導電体とを接続する電極接続用導電性接続部に並んで、印刷抵抗体（図示せず）を形成してもよい。この印刷抵抗体の抵抗値は、振動時の圧電素子の抵抗値よりも大きな値にしてある。このような抵抗値の印刷抵抗体を用いるのは、圧電発音器が使用されていないときに、加わる温度差や衝撃により圧電素子に発生する自発分極電荷によって、圧電素子が電気的に破壊されるのを防止するためである。電極接続用導電性接続部と並列にこのような抵抗体を設けておくと、圧電素子で発生した自発分極電荷はこの抵抗体を通して放電されるので、圧電素子が電気的に破壊されるのを確実に防止することができる。
【００３８】
図７（Ａ）乃至（Ｃ）は、本発明の他の実施の形態の圧電発音器の構成を説明するために用いる図である。この実施の形態は、より高い音圧と広い周波数帯域を得るために、１つの圧電発音器の中に４つの圧電振動子を組み込んだ構造を有している。図７（Ａ）はベース部材にシート部材を接合させる前の状態の分解斜視図であり、図７（Ｂ）はベース部材にケース部材を接合させる前の状態の分解斜視図であり、図７（Ｃ）はベース部材にケース部材を接合させた状態を示す圧電発音器の斜視図である。
【００３９】
符号７１１で示した部材はシート部材であり、このシート部材７１１は図１に示したシート部材１１と同様に矩形形状を有している。このシート部材７１１も。シート部材１１と同様に、ポリイミドやポリエチレンテレフタレート（ＰＥＴ）等の絶縁または合成樹脂材料からなる厚さ１０〜１００μｍのシートである。このシート部材７１１の表面上には、４つの導電電極７１５ａ〜７１５ｄと４つの接続用電極７１７ａ〜７１７ｄがそれぞれ形成されている。シート部材７１１の表面には第１の入力電極７５１及び第２の入力電極７５３が形成されている。また導電電極７１５ａ〜７１５ｄは、シート部材７１１の表面上に形成された第１の接続パターン７５５によりそれぞれ互いに接続されており、この第１の接続パターン７５５は第１の入力電極７５１と接続されている。また、接続用電極７１７ａ〜７１７ｄは、シート部材７１１の表面上に形成されている第２の接続パターン７５７によりそれぞれ互いに接続されており、この第２の接続パターン７５７は第２の入力電極７５３と接続されている。
【００４０】
符号７０３ａ〜７０３ｄで示した部材は、それぞれ大きさの異なる矩形状の圧電素子であり、各圧電素子７０３ａ〜７０３ｄの表面には表面電極７０５ａ〜７０５ｃが接合され且つ裏面には裏面電極７０７ａ〜７０７ｄ（図示せず）がそれぞれ接合されている。そしてシート部材７１１の導電電極７１５ａ〜７１５ｄの上には圧電素子７０３ａ〜７０３ｄの裏面電極７０７ａ〜７０７ｄがそれぞれ導電性接着剤を用いて接合されている。また圧電素子７０３ａ〜７０３ｄの表面電極７０５ａ〜７０５ｄと接続用電極７１７ａ〜７１７ｄとは、電極接続用導電性接続部７２３ａ〜７２３ｄにより電気的に接続されている。電極接続用導電性接続部７２３ａ〜７２３ｄは、エポキシレジン等の有機材料に銀粉末，パラジウム粉末等の導電性粉末を混練した導電性レジンペーストから形成される。各電極接続用導電性接続部７２３ａ〜７２３ｄの下部には、圧電素子７０３ａ〜７０３ｄの表面と接続用電極７１７ａ〜７１７ｄとに跨ってエポキシレジン等の絶縁樹脂材料ペーストを用いて絶縁層７２１ａ〜７２１ｄが形成されている。
【００４１】
ベース部材７１３はＰＢＴ等のプラスチック絶縁部材により形成されている。ベース部材７１３には、開口面積の異なる４つの凹部または窓部７２７ａ〜７２７ｄがそれぞれ形成されている。この凹部７２７ａ〜７２７ｄは圧電振動子７０１の振動を許容する深さを有している。このシート部材７１１は、ベース部材７１３の上に接着または溶着により接合される。
【００４２】
そしてシート部材７１３を接合したベース部材７１３の上には箱型のカバー部材７３３が接合される。カバー部材７３３の内部には各圧電振動子（または圧電素子）に個別に対応する音響空間を形成する容積の異なる４つの前気室７６１〜７６７がそれぞれ設けられている。カバー部材７３３の上部には前気室７６１〜７６７で発生した音を外部に放音するための発音孔７３５ａ〜７３５ｄがそれぞれ形成されている。
【００４３】
上述した圧電発音器において、各圧電振動子７０１ａ〜７０１ｄの共振周波数ｆ１〜ｆ４と、前気室７６１〜７６７の共振周波数ｆ５〜ｆ８とが図８（Ａ）に示す態様になるように、圧電振動子７０１ａ〜７０１ｄの特性と前気室７６１〜７６７の大きさを設計すると、図８（Ｂ）のように音圧を高くして、しかも周波数帯域を広げることができる。
【００４４】
【発明の効果】
本発明によれば、圧電振動子の表面電極と第２の導電体とを導電性レジンペーストからなる電極接続用導電性接続部により接続したので、リード線や端子金具を用いた接合に比べ、圧電発音器の全体の厚み寸法を小さくすることができて、薄型化が容易になり、圧電発音器を搭載する電子機器の薄型化に貢献できる。
【００４５】
また本発明によれば、圧電発音器の組立にはリード線や半田を用いないので、製造の自動化が容易になり、大量生産による低コスト化が実現できる。
【００４６】
さらに本発明によれば、半田付け時の熱により圧電素子の圧電性が消失するのを防ぐことができて、生産時の歩留まりが向上する。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態の圧電発音器の構成を示す分解斜視図である。
【図２】（Ａ）乃至（Ｄ）は本発明の圧電発音器を製造する場合の製造工程を製造工程順に示したものである。
【図３】本発明の他の実施の形態で用いるシート部材に圧電振動子を接合する前の状態の斜視図である。
【図４】本発明の他の実施の形態で用いるシート部材の平面図である。
【図５】本発明の他の実施の形態で用いるシート部材の断面図である。
【図６】本発明の他の実施の形態で用いるシート部材を複数配置したシートの一部平面図である。
【図７】（Ａ）は本発明の更に他の実施の形態で用いるシート部材とベース部材との構成を示す分解斜視図、（Ｂ）はベース部材とケース部材との構成を示す分解斜視図、（Ｃ）は本発明の圧電発音器の他の実施の形態の外観斜視図である。
【図８】（Ａ）は図７（Ａ）〜（Ｃ）を用いて説明した実施の形態の各圧電振動子と前気室の共振周波数の関係を示すグラフであり、（Ｂ）はこの圧電発音器から放音される音の周波数帯域と音圧との関係を示すグラフである。
【符号の説明】
１圧電振動子
３圧電素子
５表面電極
７裏面電極
９振動子支持構造
１１シート部材
１３ベース部材
１５第１の導電体
１７第２の導電体
１９第１の入力電極
２１絶縁層
２３電極接続用導電性接続部
２５枠状部材
２７窓部または凹部
２９第１の実装用端子部
３１第２の実装用端子部
３３カバー部材
３５発音孔[0001]
[Technical field to which the invention belongs]
The present invention relates to a piezoelectric sound generator using a rectangular piezoelectric element.
[0002]
[Prior art]
A piezoelectric sounder using a rectangular piezoelectric element includes a piezoelectric vibrator and a vibrator support structure that supports the piezoelectric vibrator, as in the existing piezoelectric sounder. The piezoelectric vibrator has a rectangular piezoelectric element, a surface electrode bonded on the surface of the piezoelectric element, and a back electrode bonded on the back surface of the piezoelectric element. The piezoelectric vibrator is disposed in the case and is hermetically sealed by the vibrator support structure so that the acoustic space located on the front surface side of the piezoelectric vibrator and the acoustic space located on the rear surface side do not communicate with each other inside the case. It is supported. Examples of the piezoelectric sounding device having such a structure are disclosed in Japanese Patent Application Laid-Open Nos. 11-355890 and 9-271096.
[0003]
A piezoelectric sounder disclosed in Japanese Patent Application Laid-Open No. 11-355890 has a pair of edge portions along the longitudinal direction of the piezoelectric vibrator in which both ends in the longitudinal direction of the piezoelectric vibrator are fixed using a conductive support member. However, the sound generated in the acoustic space formed on the back surface side of the piezoelectric vibrator is sealed with a flexible silicone rubber or the like so that the sound does not enter the acoustic space formed on the front surface side of the piezoelectric vibrator. Has been.
[0004]
In addition, a piezoelectric sound generator disclosed in Japanese Patent Application Laid-Open No. 9-271096 is a diaphragm of a piezoelectric vibrator in which a rectangular piezoelectric element is bonded to a diaphragm at a peripheral portion of a window portion of a resin plate having a rectangular window portion. And a pair of long sides along the longitudinal direction of the resin plate are supported by a pair of support bodies (vibrator support structure).
[0005]
[Problems to be solved by the invention]
However, these structures require two types of adhesives, an adhesive for fixing the piezoelectric vibrator and an adhesive for separating the acoustic space. For this reason, the application | coating process of each adhesive agent is required at a manufacturing process, and since the hardening time of an adhesive agent is needed, manufacturing time increased and production efficiency was bad.
[0006]
In the conventional structure, a covered lead wire is used for electrical connection between the piezoelectric vibrator and the terminal portion, and the conductor portion of the covered lead wire is joined to the electrode portion of the piezoelectric vibrator by soldering. However, the work of soldering the coated lead wire has poor workability and is very difficult to automate. Moreover, the tip temperature of the iron used for soldering is as high as 250 to 350 ° C. When such a high temperature is applied to the piezoelectric element, there is a risk of causing cracks in the piezoelectric element. Further, when a sudden temperature difference is given to the piezoelectric element, there is a risk that the piezoelectricity may be lost. It is also conceivable to use a spring metal terminal in place of the covered lead wire to achieve electrical connection only by contact. However, it is difficult to design such a spring metal terminal in a small case, and it is necessary to increase the thickness of the case, which causes a problem that it is difficult to reduce the thickness.
[0007]
An object of the present invention is to provide a piezoelectric sounder that is easy to manufacture.
[0008]
An object of the present invention is to provide a piezoelectric sounder that can be manufactured without losing the piezoelectricity of the piezoelectric element.
[0009]
An object of the present invention is to provide a piezoelectric sounder that can be reduced in thickness.
[0010]
Another object of the present invention is to provide a piezoelectric sounder that can be easily surface-mounted.
[0011]
Another object of the present invention is to provide a piezoelectric sounder having a high sound pressure.
[0012]
Another object of the present invention is to provide a piezoelectric sounder excellent in mass productivity.
[0013]
[Means for Solving the Problems]
The present invention relates to a piezoelectric vibrator having a rectangular piezoelectric element, a surface electrode bonded on the surface of the piezoelectric element, and a back electrode bonded on the back surface of the piezoelectric element, and an acoustic located on the surface side of the piezoelectric vibrator. A piezoelectric sound generator including a vibrator support structure that supports a piezoelectric vibrator so as not to communicate the space and the acoustic space located on the back side is an object of improvement. The vibrator support structure used in the present invention includes a flexible sheet member formed of an insulating material and a base member having a frame-like portion to which the outer periphery of the sheet member is joined. As the sheet member, for example, an insulating synthetic resin sheet such as polyimide or polyethylene terephthalate (PET) can be used. In the present invention, on the surface of the sheet member, a first conductor in which a portion electrically connected to the back electrode of the piezoelectric vibrator and a first input electrode connected to the portion are integrated. And a second conductor constituting a second input electrode to which a surface electrode is electrically connected is also joined to the sheet member. These conductors can be formed of a metal foil such as a copper foil. These conductors can also be formed by plating, sputtering, or the like. Further, these conductors can be formed using a conductive resin paste such as a silver resin paste.
[0014]
In the present invention, the surface electrode and the second electrode are formed by the electrode connection conductive connection portion formed by applying and curing the conductive resin paste across the surface electrode of the piezoelectric vibrator and the second conductor. The conductor is connected. The flexible sheet member does not hinder the vibration of the piezoelectric vibrator due to its flexibility. In this way, the overall thickness dimension of the piezoelectric sounder can be reduced as compared with joining using lead wires or terminal fittings. In addition, since lead wires and solder are not used, the automation of manufacturing is facilitated, and it is possible to prevent the piezoelectricity of the piezoelectric element from being lost due to heat during soldering.
[0015]
In a more specific aspect of the piezoelectric sounder of the present invention, a piezoelectric vibrator having a rectangular piezoelectric element, a surface electrode bonded on the surface of the piezoelectric element, and a back electrode bonded on the back surface of the piezoelectric element. And a vibrator support structure for supporting the piezoelectric vibrator so as not to communicate the acoustic space located on the front surface side of the piezoelectric vibrator and the acoustic space located on the back surface side. The vibrator support structure is surrounded by a flexible sheet member formed of an insulating resin material, a frame-like portion to which the outer peripheral portion of the back surface of the sheet member is joined, and the vibration of the piezoelectric vibrator. And a base member made of an insulating material provided with a recess or window portion that allows the Also in this case, on the surface of the sheet member, a first conductor in which a portion electrically connected to the back electrode of the piezoelectric vibrator and a first input electrode connected to the portion are integrated, and Bonding a second conductor constituting the second input electrode to which the surface electrode is electrically connected, applying the conductive resin paste across the surface electrode and the second conductor, and It connects by the electroconductive connection part for electrode connection formed by hardening | curing this.
[0016]
When joining the frame-shaped part of a base member and the back surface of a sheet | seat member, you may join by an adhesive agent. Further, when at least the frame-like portion of the base member and the sheet member are formed of a synthetic resin material that can be welded, the sheet member and the frame-like portion may be joined by thermal welding or ultrasonic vibration welding.
[0017]
In the case where the first and second conductors are formed of metal foil, if the end surface of the first conductor is exposed to the second conductor side, the conductive connection part for electrode connection is below It is preferable to form an insulating layer made of an insulating resin that prevents a short circuit between the conductive connecting portion and the first conductor. In addition, in the part which comprises the back electrode of a 1st conductor, the conductor acceptance recessed part into which a 2nd conductor partially enters so that it may not contact with a 1st conductor is formed, and the conductive connection for electrode connection If the portion is formed directly between the surface electrode and the second conductor located outside the conductor receiving recess, an insulating layer is formed to prevent a short circuit between the conductive connection portion and the first conductor. The manufacturing process can be reduced and the price of the product can be reduced.
[0018]
As the sheet member becomes thinner, when the sheet member is joined to the base member, wrinkles or the like may occur in the sheet member, which may make it difficult to join. In such a case, a reinforcing conductor may be formed on the surface of the sheet member along the outer edge portion of the sheet member so as not to be electrically connected to the first and second conductors. The first and second conductors and the reinforcing conductor can be formed from a metal foil. In this case, there is no problem even if the reinforcing conductor is connected to one of the first conductor and the second conductor.
[0019]
Further, if the portion of the sheet member positioned between the first conductor and the reinforcing conductor is formed in a bellows shape so as to allow the vibration of the piezoelectric vibrator, the deformation of this portion becomes easy. Even when a member is used, the piezoelectric vibrator can be vibrated sufficiently.
[0020]
In the case of constituting a surface mount type piezoelectric sound generator, the base member includes a first input electrode and a second input electrode on a portion positioned outside the sheet member in a state where the sheet member is bonded to the frame-shaped portion. First and second mounting terminal portions that are electrically connected to the input electrode are provided. Then, the first input electrode, the second input electrode, and the first and second mounting terminal portions are coated with a conductive resin paste and cured to cure the terminal connection conductivity. Connect by connection. In this way, the electrical connection between the mounting terminal portion of the surface-mounted piezoelectric sound generator and the piezoelectric vibrator can be facilitated, and the structure of the surface-mounted piezoelectric sounder is simplified.
[0021]
If the electrode connection conductive connection portion and the terminal connection conductive connection portion are formed together, the number of manufacturing steps of the piezoelectric sounder can be reduced.
[0022]
Further, it is preferable that a cover member covering the piezoelectric vibrator is fixed to the base member, and the base member and the cover member constitute a case. In this case, since the base member constitutes a part of the case, the number of parts is reduced, and the manufacturing cost can be reduced.
[0023]
When the piezoelectric sounder is not in use, spontaneous polarization charges are generated due to a temperature difference or an impact, and the piezoelectric elements may be electrically destroyed by the charges. In such a case, a printed resistor having a resistance value larger than the resistance value of the piezoelectric element during vibration is provided in parallel with the electrode connecting conductive connection portion. In this way, since the spontaneous polarization charge generated in the piezoelectric element is discharged through this resistor, it is possible to prevent the piezoelectric element from being electrically destroyed.
[0024]
In order to obtain a higher sound pressure and a wider frequency band, a plurality of piezoelectric elements are used in combination. When using such a plurality of piezoelectric elements in combination, a base member having a plurality of recesses or windows, a flexible sheet member joined to the base member and formed of an insulating material, and a base member A plurality of conductive parts formed on the surfaces of a plurality of flexible regions of a sheet member corresponding to a plurality of recesses or windows, and a plurality of rectangular piezoelectric elements in which back electrodes are joined on the plurality of conductive parts A plurality of surface electrodes respectively bonded to the surfaces of the plurality of piezoelectric elements; first and second input electrodes formed on the surface of the sheet member; and a plurality of conductive portions formed on the surface of the sheet member; A first connection pattern for electrically connecting the first input electrode, a plurality of connection electrodes formed on or near the surfaces of the plurality of flexible regions of the sheet member, and formed on the surface of the sheet member. Multiple connections Forming a second connection pattern for electrically connecting the electrode and the second input electrode, and applying a conductive resin paste across the plurality of surface electrodes and the plurality of connection electrodes and curing the same. A plurality of electrode connection conductive connections for connecting the plurality of surface electrodes and the plurality of connection electrodes, respectively, and a plurality of acoustic spaces attached to the base member and individually corresponding to the plurality of piezoelectric elements. A piezoelectric sounder is composed of a cover member having a structure. In this case, by appropriately selecting the resonance frequency of each piezoelectric vibrator and the resonance frequencies of a plurality of acoustic spaces, the sound pressure of the piezoelectric sounder can be increased as compared with the case of using one piezoelectric vibrator. In addition, the frequency band can be expanded.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is an exploded perspective view showing the configuration of the piezoelectric sounder according to the first embodiment of the present invention. FIG. 1 shows a state in which a cover member and a base member, which will be described later, are separated. In FIG. 1, the member denoted by reference numeral 1 is a piezoelectric vibrator. The piezoelectric vibrator 1 includes a rectangular piezoelectric element 3 made of piezoelectric ceramic such as PTZ, a surface electrode 5 bonded on the surface of the piezoelectric element 3, and a back electrode 7 bonded on the back surface of the piezoelectric element 3. (Not shown in the drawing). The front surface electrode 5 and the back surface electrode 7 are formed, for example, by printing a conductive paste obtained by kneading silver powder into a glass paste on both surfaces of the piezoelectric element 3 and firing it. The piezoelectric element 3 is previously polarized by applying a DC voltage between the front electrode 5 and the back electrode 7. Therefore, when a pulse voltage having a predetermined period is applied between the front electrode 5 and the back electrode 7, the piezoelectric element 3 vibrates at the predetermined frequency.
[0026]
Reference numeral 9 denotes a vibrator support structure that supports the piezoelectric vibrator 1. The vibrator support structure 9 includes a sheet member 11 and a base member 13. The sheet member 11 has a rectangular shape and is made of an insulating or synthetic resin material such as polyimide or polyethylene terephthalate (PET) or a sheet having a thickness of 10 to 100 μm. Flexibility. On the surface of the sheet member 11, for example, a metal foil such as a copper foil, a first conductor 15 and a second conductor 17 having a thickness of a thin film conductor (for example, 10 to 250 μm) formed by sputtering or vapor deposition are formed. Has been. A first input electrode 19 is integrally provided on the first conductor 15 so as to be electrically connected to the back electrode 7 of the piezoelectric element 3. The back electrode 7 of the piezoelectric element 3 may be connected to the connection portion of the first conductor 15 using a resin adhesive or a conductive adhesive. The second conductor 17 constitutes a second input electrode to which the surface electrode 5 of the piezoelectric element 3 is connected.
[0027]
The surface electrode 5 of the piezoelectric element 3 and the second conductor 17 are electrically connected by an electrode connecting conductive connection portion 23. Note that an insulating layer 21 is formed under the conductive connecting portion 23 for electrode connection using an insulating resin material paste such as epoxy resin across the surface of the piezoelectric element 3 and the second conductor 17. The insulating layer 21 prevents the electrode connecting conductive connection portion 23 from coming into contact with the first conductor 15 and causing a short circuit. The electrode connecting conductive connecting portion 23 is formed of a conductive resin paste obtained by kneading a conductive powder such as silver powder or palladium powder in an organic material such as epoxy resin. Since the epoxy resin and the conductive resin paste for forming the insulating layer 21 can usually be cured at a temperature of 150 ° C. or lower, the piezoelectricity of the piezoelectric element 3 is not lost in the curing step.
[0028]
The sheet member 11 is bonded onto the base member 13. The base member 13 is formed of a plastic insulating member such as PBT. The base member 13 has a structure in which a frame-shaped member 25 having a rectangular outline shape is integrated with a surface of a rectangular plate-shaped main body. A window or recess 27 is formed in the region surrounded by the frame-shaped portion 25. The recess 27 has a depth that allows vibration of the piezoelectric vibrator 1. The outer peripheral portion of the back surface of the sheet member 11 is joined to the upper surface of the frame-shaped portion 25 using an adhesive, a welding technique, or the like. At both ends in the longitudinal direction of the base member 13, the first mounting terminal portion 29 and the second mounting terminal portion 31 constituting the soldering terminal portions for surface mounting are provided outside the frame-shaped member 25. Is provided. These mounting terminal portions 29 and 31 are insert-molded in the base member 13. The first mounting terminal portion 29 is electrically connected to the first input electrode 19 by a terminal connection conductive connection portion (not shown). Further, the second mounting terminal portion 31 is electrically connected to the second conductor 17 constituting the second input electrode by a terminal connection conductive connection portion (not shown). These conductive connection parts for terminal connection are made of a conductive resin paste obtained by kneading a conductive powder such as silver powder or palladium powder in an organic material such as epoxy resin in the same manner as the conductive connection part 23 for electrode connection described above. It is formed. Therefore, when forming the electrode connection conductive connection portion 23, the terminal connection conductive connection portion for connecting the second mounting terminal portion 31 and the second conductor 17 is formed at the same time. It may be.
[0029]
A member denoted by reference numeral 33 is a box-shaped cover member, and is joined to the base member 13 with an adhesive or the like. By joining the cover member 33 to the base member 13, an acoustic space (front air chamber) is formed on the front side of the piezoelectric vibrator 1. In addition, an acoustic space (rear air chamber) on the rear side of the piezoelectric vibrator 1 is formed in a concave portion 27 surrounded by a frame-like member 25 closed by the sheet member 11. The sound generated by the vibration of the piezoelectric vibrator 1 is emitted to the outside from the sound generation hole 35 provided in the upper part of the cover member 33.
[0030]
Next, a method for manufacturing the piezoelectric sounder shown in FIG. 1 will be described in the order of manufacturing steps. 2 (A) to 2 (D) show manufacturing steps in the order of manufacturing steps when manufacturing the piezoelectric sounder of the present invention. First, the surface electrode 5 is formed on the surface of the piezoelectric element 3 made of piezoelectric ceramic such as PZT, and the back electrode 7 is formed on the back surface of the piezoelectric element 3. Next, on the surface of the sheet member 11, a first conductor 15 electrically connected to the back electrode 7 of the piezoelectric element 3 in FIG. 2A, and a surface electrode 5 of the piezoelectric element 3 in FIG. A second conductor 17 to be electrically connected is formed.
[0031]
Next, as shown in FIG. 2C, a resin adhesive or conductive adhesive is applied to the back surface electrode 7 side of the piezoelectric element 3 on the first conductor 15 formed on the surface of the sheet member 11. Use together. Then, the surface electrode 5 of the piezoelectric element 3 and the second conductor 17 are electrically connected. For the connection method, an organic insulating resist is applied so as to cover the side surface of the piezoelectric element 3 to form an insulating layer 21, and organic silver is straddled between the surface electrode 5 and the second conductor 17 from above. A conductive resin paste made of is applied by printing and then cured.
[0032]
Next, as shown in FIG. 2 (D), the outer peripheral portion of the sheet member 11 with the piezoelectric element 3 attached on the surface in FIG. 2 (C) is used as a frame-like portion 25 of the base member 13 that becomes the base of the piezoelectric sounder. Join using adhesive or heat welding. Then, a conductive resin paste is applied between the first input electrode 17 and the first mounting terminal 29 and between the second input electrode 19 and the second mounting terminal 29 so as to straddle both. It is applied by printing and then cured to make an electrical connection between them. Finally, the case member 33 shown in FIG. 1 is joined to the base member 13 by an adhesive, thermocompression bonding, or the like.
[0033]
FIG. 3 is a perspective view of a state before the piezoelectric vibrator 1 is joined to the sheet member 111 used in another embodiment of the present invention. In the embodiment of FIG. 3, the same parts as those constituting the embodiment shown in FIG. 1 are denoted by the same reference numerals as those in FIG. In this embodiment, the connection portion of the first conductor 115 that is electrically connected to the back electrode 7 of the piezoelectric vibrator 1 is not in contact with the first conductor 115 and the second conductor 117. The conductor receiving recess 116 is formed so as to partially enter. A part of the second conductor 117 is formed in the conductor receiving recess 116. Using the sheet member 111 on which these conductors are formed, the electrode connection conductive connection portion 23 shown in FIG. 1 and FIG. 2 is used as a second conductor located outside the surface electrode 5 and the conductor receiving recess 116. If it is formed directly between the bodies 117, there is no need to provide the insulating layer 21 to be formed to prevent a short circuit between the electrode connecting conductive connection portion 23 and the first conductor 115, thereby reducing the number of manufacturing steps. be able to.
[0034]
FIG. 4 is a plan view of a sheet member 211 used in another embodiment of the present invention. A first conductor 215 and a second conductor 217 are formed on the surface of the sheet member 211. And from the same metal foil as the metal foil which forms the 1st conductor 215 and the 2nd conductor 217 in the outer edge part of the sheet | seat member 211 so that the 1st conductor 215 and the 2nd conductor 217 may be enclosed. Reinforcing conductors 251 and 253 are formed. The reason why the reinforcing conductors 251 and 253 are provided is as follows. When the sheet member 211 is joined to the base member, the thinner the sheet member 211 is, the more wrinkles are generated on the sheet member, and the joining becomes difficult. In such a case, if the reinforcing conductors 251 and 253 shown in FIG. 4 are provided to increase the strength of the outer peripheral portion of the sheet member 211, wrinkles are not generated in the outer peripheral portion of the sheet member 211. And the base member can be smoothly joined. Note that there is no problem even if the reinforcing conductors 251 and 253 are connected to either the first conductor 115 or the second conductor 117.
[0035]
FIG. 5 is a cross-sectional view used for explaining another embodiment of the present invention, and this figure is a cross-sectional view taken along the line AA of FIG. The sheet member 311 shown in FIG. 5 has a bellows-like shape in two portions 350 and 360 of the sheet member 211 located between the first conductor 215 and the reinforcing conductors 251 and 253 of the sheet member 211. Corrugated processing is applied. If such portions 350 and 360 are provided, these portions can be easily deformed, and the piezoelectric vibrator can be sufficiently vibrated.
[0036]
FIG. 6 is a view showing a part of a multiple sheet member assembly 550 used in mass production of the above-described embodiments. The sheet member connector 550 is formed by etching a metal foil stretched on a flexible substrate such as polyimide. Feeding guide holes 560 are formed at both ends in the width direction (direction orthogonal to the longitudinal direction) of the illustrated sheet member coupling body 550 with a predetermined interval in the longitudinal direction. Projections provided on the outer periphery of a guide roller (not shown) are inserted into the guide holes 560 for feeding, and the sheet member coupling body 550 is fed in the longitudinal direction. If a piezoelectric vibrator is bonded to such a sheet member coupling body 550 to form a conductive connection part for electrode connection, then each sheet member is cut out to produce a component to be bonded to the base member. Mass production becomes easy.
[0037]
In each of the above-described embodiments, the printed resistor (see FIG. 5) is arranged side by side with the electrode connection conductive connection portion that connects the surface electrode of the piezoelectric vibrator and the first conductor formed on the surface of the sheet member. (Not shown) may be formed. The resistance value of the printed resistor is set larger than the resistance value of the piezoelectric element during vibration. A printed resistor having such a resistance value is used when the piezoelectric sounder is not used, and the piezoelectric element is electrically destroyed by a spontaneous polarization charge generated in the piezoelectric element due to an applied temperature difference or impact. This is to prevent this. If such a resistor is provided in parallel with the conductive connection part for electrode connection, the spontaneous polarization charge generated in the piezoelectric element is discharged through this resistor, so that the piezoelectric element is electrically destroyed. It can be surely prevented.
[0038]
FIGS. 7A to 7C are diagrams used to describe the configuration of a piezoelectric sounder according to another embodiment of the present invention. This embodiment has a structure in which four piezoelectric vibrators are incorporated in one piezoelectric sound generator in order to obtain a higher sound pressure and a wider frequency band. 7A is an exploded perspective view of the state before the sheet member is joined to the base member, and FIG. 7B is an exploded perspective view of the state before the case member is joined to the base member. (C) is a perspective view of a piezoelectric sounder showing a state in which a case member is joined to a base member.
[0039]
The member denoted by reference numeral 711 is a sheet member, and the sheet member 711 has a rectangular shape like the sheet member 11 shown in FIG. This sheet member 711 also. Similar to the sheet member 11, the sheet is a 10 to 100 μm thick sheet made of an insulating or synthetic resin material such as polyimide or polyethylene terephthalate (PET). On the surface of the sheet member 711, four conductive electrodes 715a to 715d and four connection electrodes 717a to 717d are formed, respectively. A first input electrode 751 and a second input electrode 753 are formed on the surface of the sheet member 711. The conductive electrodes 715 a to 715 d are connected to each other by a first connection pattern 755 formed on the surface of the sheet member 711, and the first connection pattern 755 is connected to the first input electrode 751. Yes. The connection electrodes 717 a to 717 d are connected to each other by a second connection pattern 757 formed on the surface of the sheet member 711, and the second connection pattern 757 is connected to the second input electrode 753. It is connected.
[0040]
The members denoted by reference numerals 703a to 703d are rectangular piezoelectric elements having different sizes. The surface electrodes 705a to 705c are bonded to the front surfaces of the piezoelectric elements 703a to 703d, and the back electrodes 707a to 707d are connected to the back surfaces. (Not shown) are joined to each other. Then, the back electrodes 707a to 707d of the piezoelectric elements 703a to 703d are joined to the conductive electrodes 715a to 715d of the sheet member 711 using a conductive adhesive, respectively. The surface electrodes 705a to 705d of the piezoelectric elements 703a to 703d and the connection electrodes 717a to 717d are electrically connected by electrode connection conductive connection portions 723a to 723d. The electrode connection conductive connection portions 723a to 723d are formed from a conductive resin paste obtained by kneading a conductive powder such as silver powder or palladium powder in an organic material such as epoxy resin. Insulating layers 721a to 721d are formed below the conductive connecting portions 723a to 723d for electrode connection using an insulating resin material paste such as epoxy resin across the surfaces of the piezoelectric elements 703a to 703d and the connecting electrodes 717a to 717d. Is formed.
[0041]
The base member 713 is formed of a plastic insulating member such as PBT. The base member 713 is formed with four concave portions or window portions 727a to 727d having different opening areas. The recesses 727a to 727d have a depth that allows the piezoelectric vibrator 701 to vibrate. The sheet member 711 is bonded onto the base member 713 by adhesion or welding.
[0042]
A box-shaped cover member 733 is joined on the base member 713 to which the sheet member 713 is joined. Inside the cover member 733, four front air chambers 761 to 767 having different volumes that form acoustic spaces individually corresponding to the respective piezoelectric vibrators (or piezoelectric elements) are provided. Sound generation holes 735a to 735d for emitting sounds generated in the front air chambers 761 to 767 to the outside are formed in the upper part of the cover member 733, respectively.
[0043]
In the piezoelectric sound generator described above, the piezoelectric frequencies are set so that the resonance frequencies f1 to f4 of the piezoelectric vibrators 701a to 701d and the resonance frequencies f5 to f8 of the front air chambers 761 to 767 are in the form shown in FIG. When the characteristics of the vibrators 701a to 701d and the sizes of the front air chambers 761 to 767 are designed, the sound pressure can be increased and the frequency band can be expanded as shown in FIG.
[0044]
【The invention's effect】
According to the present invention, since the surface electrode of the piezoelectric vibrator and the second conductor are connected by the conductive connecting portion for electrode connection made of a conductive resin paste, compared to joining using a lead wire or a terminal fitting, The overall thickness of the piezoelectric sounder can be reduced, making it easy to reduce the thickness, and contributing to reducing the thickness of an electronic device equipped with the piezoelectric sounder.
[0045]
Further, according to the present invention, since lead wires and solder are not used for assembling the piezoelectric sound generator, it becomes easy to automate the manufacturing, and cost reduction by mass production can be realized.
[0046]
Furthermore, according to the present invention, it is possible to prevent the piezoelectricity of the piezoelectric element from being lost due to heat at the time of soldering, and the yield during production is improved.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing a configuration of a piezoelectric sounder according to a first embodiment of the present invention.
FIGS. 2A to 2D show manufacturing steps in the order of manufacturing steps when manufacturing the piezoelectric sounder of the present invention.
FIG. 3 is a perspective view of a state before a piezoelectric vibrator is bonded to a sheet member used in another embodiment of the present invention.
FIG. 4 is a plan view of a sheet member used in another embodiment of the present invention.
FIG. 5 is a cross-sectional view of a sheet member used in another embodiment of the present invention.
FIG. 6 is a partial plan view of a sheet in which a plurality of sheet members used in another embodiment of the present invention are arranged.
7A is an exploded perspective view showing a configuration of a sheet member and a base member used in still another embodiment of the present invention, and FIG. 7B is an exploded perspective view showing a configuration of the base member and the case member. (C) is an external perspective view of another embodiment of the piezoelectric sounder of the present invention.
FIG. 8A is a graph showing the relationship between the resonance frequency of each piezoelectric vibrator and the front air chamber according to the embodiment described with reference to FIGS. 7A to 7C, and FIG. It is a graph which shows the relationship between the frequency band of the sound emitted from a piezoelectric sound generator, and a sound pressure.
[Explanation of symbols]
1 Piezoelectric vibrator
3 Piezoelectric elements
5 Surface electrode
7 Back electrode
9 Vibrator support structure
11 Sheet material
13 Base member
15 First conductor
17 Second conductor
19 First input electrode
21 Insulating layer
23 Conductive connection for electrode connection
25 Frame-shaped member
27 Window or recess
29 First mounting terminal section
31 Second mounting terminal section
33 Cover member
35 pronunciation hole

Claims

A piezoelectric vibrator having a rectangular piezoelectric element, a surface electrode joined on the surface of the piezoelectric element, and a back electrode joined on the back face of the piezoelectric element, and an acoustic space located on the surface side of the piezoelectric vibrator And a piezoelectric sound generator comprising a vibrator support structure that supports the piezoelectric vibrator so as not to communicate with an acoustic space located on the back side,
The vibrator support structure includes a flexible sheet member formed of an insulating material and a base member having a frame-like portion to which an outer peripheral portion of the sheet member is joined.
On the surface of the sheet member, a first conductor in which a portion electrically connected to the back electrode of the piezoelectric vibrator and a first input electrode connected to the portion are integrated, and A second conductor constituting a second input electrode to which the surface electrode is electrically connected is joined;
The piezoelectric device characterized in that the surface electrode and the second conductor are connected by a conductive connecting portion for electrode connection formed by applying and curing a conductive resin paste across the two. Sound generator.

A piezoelectric vibrator having a rectangular piezoelectric element, a surface electrode joined on the surface of the piezoelectric element, and a back electrode joined on the back face of the piezoelectric element, and an acoustic space located on the surface side of the piezoelectric vibrator And a piezoelectric sound generator comprising a vibrator support structure that supports the piezoelectric vibrator so as not to communicate with an acoustic space located on the back side,
The vibrator support structure is surrounded by the flexible sheet member formed of an insulating resin material, a frame-like portion to which an outer peripheral portion of the back surface of the sheet member is joined, and the frame-like portion. It consists of a base member made of an insulating material with a recess or window that allows vibration of the child,
On the surface of the sheet member, a first conductor in which a portion electrically connected to the back electrode of the piezoelectric vibrator and a first input electrode connected to the portion are integrated, and A second conductor constituting a second input electrode to which the surface electrode is electrically connected is joined;
The piezoelectric device characterized in that the surface electrode and the second conductor are connected by a conductive connecting portion for electrode connection formed by applying and curing a conductive resin paste across the two. Sound generator.

3. The piezoelectric sounding device according to claim 1, wherein the frame-shaped portion of the base member and the back surface of the sheet member are bonded together by an adhesive.

The at least the frame-like portion and the sheet member of the base member are formed of a weldable synthetic resin material, and the sheet member and the frame-like portion are joined by welding. The piezoelectric sound generator according to 1.

The first and second conductors are formed of a metal foil,
An insulating layer made of an insulating resin that prevents a short circuit between the electrode connecting conductive connection portion and the first conductor is formed under the electrode connecting conductive connecting portion. The piezoelectric sounder according to claim 1 or 2.

In the portion constituting the back electrode of the first conductor, a conductor receiving recess is formed in which the second conductor partially enters so as not to contact the first conductor,
3. The piezoelectric device according to claim 1, wherein the conductive connecting portion for electrode connection is directly formed between the surface electrode and the second conductor located outside the conductor receiving recess. 4. Sound generator.

A reinforcing conductor is formed on the surface of the sheet member along the outer edge portion of the sheet member so as not to electrically connect the first and second conductors. The piezoelectric sounder according to claim 1 or 2, wherein the two conductors and the reinforcing conductor are formed of a metal foil.

The portion of the sheet member positioned between the first conductor and the reinforcing conductor is formed in a bellows shape so as to allow vibration of the piezoelectric vibrator. The piezoelectric sound generator according to 1 or 2.

The base member is electrically connected to the first input electrode and the second input electrode at a portion located outside the sheet member in a state where the sheet member is joined to the frame-shaped portion. First and second mounting terminal portions are provided,
The first input electrode and the second input electrode and the first and second mounting terminal portions are formed by applying a conductive resin paste across both and curing the conductive resin paste. The piezoelectric sounding device according to claim 1, wherein the piezoelectric sounding device is connected by a sexual connecting portion.

10. The piezoelectric sounding device according to claim 9, wherein the electrode connection conductive connection portion and the terminal connection conductive connection portion are formed together.

3. The piezoelectric sounding device according to claim 1, wherein a cover member that covers the piezoelectric vibrator is fixed to the base member, and a case is constituted by the base member and the cover member.

3. The piezoelectric sounder according to claim 1, wherein a printed resistor having a resistance value larger than a resistance value of the piezoelectric element during vibration is formed in parallel with the conductive connecting portion for electrode connection.

A base member having a plurality of recesses or windows;
A flexible sheet member joined to the base member and formed of an insulating material;
A plurality of conductive portions formed on the surface of the plurality of flexible regions of the sheet member corresponding to the plurality of recesses or windows of the base member;
A plurality of rectangular piezoelectric elements in which back electrodes are bonded onto the plurality of conductive electrodes;
A plurality of surface electrodes respectively bonded to the surfaces of the plurality of piezoelectric elements;
First and second input electrodes formed on the surface of the sheet member;
A first connection pattern formed on the surface of the sheet member to electrically connect the plurality of conductive portions and the first input electrode;
A plurality of connection electrodes formed on or near the surface of the plurality of flexible regions of the sheet member;
A second connection pattern formed on the surface of the sheet member to electrically connect the plurality of connection electrodes and the second input electrode;
A plurality of conductive resin pastes are applied across the plurality of surface electrodes and the plurality of connection electrodes and cured to form a plurality of surfaces for connecting the plurality of surface electrodes and the plurality of connection electrodes, respectively. A conductive connection for electrode connection;
And a cover member that is attached to the base member and has a structure that forms a plurality of acoustic spaces individually corresponding to the plurality of piezoelectric elements.