JP3649151B2

JP3649151B2 - Flexural transducer

Info

Publication number: JP3649151B2
Application number: JP2001145923A
Authority: JP
Inventors: 博史芝
Original assignee: NEC Corp
Current assignee: NEC Corp
Priority date: 2001-05-16
Filing date: 2001-05-16
Publication date: 2005-05-18
Anticipated expiration: 2021-05-16
Also published as: JP2002345082A

Description

【０００１】
【発明の属する技術分野】
この発明は、水中に音波を放射する電気音響変換器に係り、特に、円筒形に並べられた複数の振動板の屈曲振動により水中に音波を放射する屈曲型送受波器に関する。
【０００２】
【従来の技術】
従来、この種の屈曲型送受波器は、電気／機械変換素子として円筒形振動子を積層し、円筒形振動子の外面又は内面に絶縁シースを設け、リード線を介して送受信する構造であり、送波音圧を高く得るためには、円筒形振動子の呼吸振動モードによる共振を利用して送信周波数を設定していた。しかし、この種の送受波器は、円筒形振動子の剛性が高いために呼吸振動モードによる共振周波数が高くなり、逆に、呼吸振動モードによる共振周波数を低くしようとすると、装置全体の外径が大きくなるという欠点があった。
【０００３】
このため、低周波数で小型・軽量の送受波器を得るために、円筒型振動子のたて振動と、この円筒型振動子に支点を提供する支持リングの支持力とにより、振動板にたわみ共振を起こさせると共に、振動板内面空間で音響管を構成して振動板の内面放射音波を遅相してほぼ同位相と外面放射音波に重畳する必要があった。すなわち、円筒形状の軸方向に設けられた複数の振動板の屈曲振動モードを利用し、この屈曲振動モードの共振周波数を低くすることにより、周波数の音波を小型・軽量の屈曲型送受波器で得るものである。
【０００４】
上述した従来例の一例として、例えば特開平２−３０９７９９号公報に示された送受波器（以下、第１の従来例という）がある。以下、この第１の従来例について説明する。
まず、この従来例の構成について説明する。図７は、上述した第１の従来例の屈曲型送受波器の構成を示す概略図である。この例は、円筒形振動体３ａ，３ｂの円周上に、例えば、８片の振動板２が並べられ、並べられた８片の振動板２を固定するように、上下端部に支持リング４ａ，４ｂが設けられ、これら全体の外周囲は、外部シート１により覆われ、水密保護されている構造を有している。しかしながら、振動板２の振動による発生音波は、振動板２の内外面で位相が反転し、内面放射音波がそのまま外面放射音波に重畳されるので、音波短絡現象を引き起こし、外面放射音波エネルギーを抑圧してしまう。このため、この短絡現象を回避するために、振動子２の内面放射音波の位相を外面放射音波の位相に合致させるように構成されている。
【０００５】
次に、この従来例の動作について説明する。図８は、上述した第１の従来例の屈曲型送受波器の縦断面の一部分を示す部分断面図である。まず、円筒形振動体３ａ，３ｂにリード線５を介して、振動板２の屈曲振動モードで生じる機械共振周波数（ｆｒ）と同じ周波数の電気信号を加えると、円筒形振動体３ａ，３ｂの径方向振動が発生し、この径方向振動により支持リング４ａ，４ｂを支点とした振動板２の屈曲振動モードが発生する。この屈曲振動モードによる機械的共振により、低周波の音響出力を得ることができる。機械的共振周波数ｆｒは、振動板２の長さをＬ（ｃｍ）、厚みをｔ（ｃｍ）とし、縦弾性係数をＥ（ｋｇ／ｃｍ^２）、密度をρ（ｋｇ／ｃｍ^３）、ポアソン比をα、振動系により定まる無次元係数をσとすると、簡単には、以下の式で表される。
ｆｒ＝απｔ／２Ｌ^２｛Ｅ／３（１−σ^２）ρ｝^１／２・・・（１）
すなわち、機械的共振周波数ｆｒは、振動板２の材質及び寸法に依存して１つの値に決まってしまうものである。
【０００６】
従って、上記第１の従来装置にあっては、小型軽量の屈曲型送受波器で低周波数の音響放射を行うことができるものの、上述したように、構成する振動板の屈曲振動モードによる機械的共振周波数ｆｒが振動板の材質及び寸法に依存して１つの値に決まってしまい、一定以上の送受波レベルが得られる周波数帯域が狭くなっている。
【０００７】
そこで、上述したような低周波数を得るために、一定以上の送波レベルが得られる周波数帯域を広くするために、円筒形振動子が呼吸振動を行い、分割板に径方向の駆動力を加えるものとして、特開平０９−０３７３７９号公報記載の超音波振動子及びその製造方法（以下、第２の従来例という）がある。第２の従来例は、圧電セラミックスからなる円環状あるいは円筒状の圧電振動子内において、その円筒径方向であってその円筒軸方向に垂直な面内に、空孔群が分布された面が、圧電振動子の円筒径の面においてその厚さの１／３以下のピッチで複数箇所に形成された構成である。このような空孔群は、圧電振動子のヤング率を低下させて、厚さ方向以外の共振モードの結合を小さくする働きがあり、内面電極及び外面電極に高電圧を印加すると、圧電振動子が、厚さ方向に分極された円環形状で厚み振動を行い、円筒波を放射している。
【０００８】
【発明が解決しようとする課題】
しかしながら、上記第２の従来装置にあっても、溝の代わりに圧電セラミックの空孔群を形成し、この空孔群により圧電振動子のヤング率を低下させ、円筒形振動子が呼吸運動を行い径方向の駆動力を発生するものであるので、圧電セラミックの製造方法に細心の注意を払う必要があり、また、圧電振動子形成工程，焼成工程，電極形成工程と製造方法が非常に複雑になり、さらに、目的の送受波器を製造するためには、かなりの大きさを必要とするという問題があった。
【０００９】
この発明は、上述した事情に鑑みてなされたもので、小型かつ低周波数を達成する振動板の屈曲振動モードを利用し、かつ、広い周波数帯域で一定以上の送波レベルが得られる屈曲型送受波器を提供することを目的としている。
【００１０】
【課題を解決するための手段】
上記課題を解決するために、請求項１記載の発明は、円筒形弾性体を円周方向に複数に等分割し軸方向に互いに平行に分離して円筒形に配列された複数の振動板と、該複数の振動板を円筒形の軸方向に等分割する複数のスリットと、上記円筒形に配列された複数の振動板の軸方向両端部に設けられた一対の円筒形振動体と、該一対の円筒形振動体に電気的信号を与えるために該円筒形振動体に接続されたリード線と、上記円筒形全体を覆う絶縁シースとを備え、上記複数の振動板が上記円筒形の径方向に屈曲することにより生じる屈曲振動と、上記一対の円筒形振動体及び上記複数の振動板が上記円筒形の径方向に移動することにより生じる呼吸振動との共振により、水中に音波を放射する屈曲型送受波器であって、
上記一対の円筒形振動体と上記絶縁シースとの間に接着して設けられ、上記一対の円筒形振動体の外径と同じ外径を有する円形の板により形成され、所定の位置に上記リード線を貫通させる穴を有する１対のプレートと、上記一対のプレート間の間隔が一定となるように、上記一対のプレートを固定するボルト及びナットとを備え、上記一対の円筒形振動体及び上記複数の振動板の呼吸振動に合わせて上記一対のプレートを径方向へ伸縮させるために、上記一対のプレートを、厚み方向の剛性が比較的高く、径方向の剛性が比較的低い一方向強度材料より形成したことを特徴としている。
【００１１】
また、請求項２記載の発明は、請求項１記載の屈曲型送受波器に係り、上記一対のプレートの上記一方向強度材料により、上記呼吸振動による音波の周波数を上記屈曲振動による音波の周波数に近接させ、上記呼吸振動による音波の周波数を上記屈曲振動による音波の周波数に重畳させ、一定以上の送受波レベルが得られ、広い周波数帯域で低い機械的共振周波数の音波を放射できることを特徴としている。
【００１２】
また、請求項３記載の発明は、請求項１又は２記載の屈曲型送受波器に係り、上記一対の円筒形振動体は、上記複数の振動板により形成された円筒形配列の中心軸と同軸で、かつ、上記複数の振動板の円筒形配列外周とほぼ同じ外周と、上記複数の振動板の円筒形配列内周よりも小径の内周とを有することを特徴としている。
【００１３】
また、請求項４記載の発明は、請求項１又は２記載の屈曲型送受波器に係り、上記一対の円筒形振動体は、上記複数の振動板の円筒形配列の内径に等しい外径を有し、上記複数の振動板の円筒形状配列の軸方向の中央と両端部との間にそれぞれ設けられたことを特徴としている。
【００１４】
また、請求項５記載の発明は、請求項１乃至４のいずれか１に記載の屈曲型送受波器に係り、上記一対のプレートのいずれか一方のプレートの中心部にボルトが貫通し、該ボルトを他方のプレートの中心部に配置されたナットによって締め付けることにより、上記一対のプレートを固定したことを特徴としている。
【００１５】
また、請求項６記載の発明は、請求項１乃至５のいずれか１に記載の屈曲型送受波器に係り、上記一対のプレートと、上記ボルト及びナットとの境界面には、弾性体が充填され、水密保護されていることを特徴としている。
【００１６】
また、請求項７記載の発明は、請求項６記載の屈曲型送受波器に係り、上記弾性体が、合成樹脂であることを特徴としている。
【００１７】
また、請求項８記載の発明は、請求項１乃至７のいずれか１に記載の屈曲型送受波器に係り、上記一対の円筒形振動体は、円周方向にリング状に並べられた複数のアクティブ振動体と、上記複数のアクティブ振動体の間に配置された複数の周波数調整材と、上記複数のアクティブ振動体及び上記複数の周波数調整材の外周囲を締め付けて固定する繊維材とを有する一対の複合円筒形振動体であることを特徴としている。
【００１８】
また、請求項９記載の発明は、請求項８記載の屈曲型送受波器に係り、上記複数のアクティブ振動体の各々は、円柱又は角柱であることを特徴としている。
【００１９】
また、請求項１０記載の発明は、請求項８又は９記載の屈曲型送受波器に係り、上記周波数調整材の密度を調整することにより、上記一対の複合円筒形振動体の径方向の呼吸振動による音波の周波数を調整することを特徴としている。
【００２０】
また、請求項１１記載の発明は、請求項１０記載の屈曲型送受波器に係り、上記周波数調整材の密度を増大することにより、上記呼吸振動による周波数を低くし、上記屈曲振動による音波の周波数に近接させることを特徴としている。
【００２１】
また、請求項１２記載の発明は、請求項１１記載の屈曲型送受波器に係り、上記呼吸振動による音波の周波数帯と上記屈曲振動による音波の周波数帯とを重畳させ、広い共振周波数帯域幅で一定以上の送波レベルが得られることを特徴としている。
【００２２】
以上説明したように、この発明の第１の手段では、屈曲型送受波器の上下端面に円筒形の長さ方向には剛性が強く、円筒形の径方向には剛性が低い一方向強化材により形成されたプレートを配置し、プレートをボルト及びナットによって締め付けて固定している。
【００２３】
また、この発明の第２の手段では、第１の手段を有する屈曲型送受波器において、円筒形振動体をアクティブ振動体と周波数調整材とを円形に並べてその外周囲を繊維材により巻き込んで円筒形に形成した複合円筒形振動体を用いている。
【００２４】
【作用】
第１の手段では、円筒形振動体が円周方向の拡がりによる呼吸振動モードを発生させたとき、プレートも円筒形振動体の呼吸振動モードに追従して径拡がりを行うため、円筒形振動体の呼吸振動モードの動作を妨げることなく、円筒形振動体と振動板とで形成する円筒形状全体の呼吸振動モードを得ることができる。従って、円筒形振動体の縦振動によって生じる振動板の屈曲振動モードによる共振周波数と合わせて、２つの共振周波数を実現することができる。
また、第２の手段では、周波数調整材により複合円筒形振動体の呼吸振動モードによる共振周波数を下げることができ、この呼吸振動モードによる共振周波数を振動板の屈曲振動モードによる共振周波数に近づけることができる。
【００２５】
【発明の実施の形態】
以下、図面を参照して、この発明の実施の形態について詳細に説明する。説明は実施例を用いて具体的に行う。
◇第１実施例
まず、この発明の第１実施例の構成について説明する。
図１は、この発明の第１実施例である屈曲型送受波器の構成を示す概略図である。この例は、円筒形弾性体を円周方向に複数に等分割し軸方向に互いに平行に分離して円筒形に配列された複数の振動板２と、複数の振動板２を円筒形の軸方向に等分割する複数のスリット８と、円筒形に配列された複数の振動板２の軸方向両端部に設けられた一対の円筒形振動体３ａ，３ｂと、一対の円筒形振動体３ａ，３ｂに電気的信号を与えるために円筒形振動体３ａ，３ｂに接続されたリード線５と、円筒形全体を覆う絶縁シース１とを備える。特に、この例は、特に、一対の円筒形振動体３ａ，３ｂと絶縁シース１との間に接着して設けられ、一対の円筒形振動体３ａ，３ｂの外径と同じ外径を有する円形の板により形成され、所定の位置にリード線５を貫通させる穴を有する一対のプレート４０ａ，４０ｂと、一対のプレート４０ａ，４０ｂ間の間隔が一定となるように、一対のプレート４０ａ，４０ｂを固定するボルト６及びナット７とを備え、一対の円筒形振動体３ａ，３ｂ及び複数の振動板２の呼吸振動に合わせて一対のプレート４０ａ，４０ｂを径方向へ伸縮させるために、一対のプレート４０ａ，４０ｂを、厚み方向の剛性が高く、径方向の剛性が低い一方向強度材料より形成したことを特徴としている。これにより、複数の振動板２が円筒形の径方向に屈曲することにより生じる屈曲振動と、一対の円筒形振動体３ａ，３ｂ及び複数の振動板２が円筒形の径方向に移動することにより生じる呼吸振動とにより、音響管を構成し、水中に音波放射する屈曲型送受波器である。
【００２６】
次に、この例の各部の詳細構成について説明する。複数の振動板２は、金属又は合成樹脂等の弾性体により円筒形状に形成され、円筒形弾性体の内周の軸方向に平行に設けられた複数のスリット８により、複数にほぼ等分割され、かつ互いに分離されて配列されている。また、複数の振動板２の円筒形状配列の軸方向寸法は、音波のほぼ半波長から１波長間に設定され、複数の振動板２の屈曲振動により水中に音波放射することができる。また、複数の振動板２は、ここでは、円筒形状（横断面が円形）に配置されているが、その形状は、必要に応じて、フラット形状（横断面が多角形）、コンケープ形状（横断面が凹状の波線）、あるいはコンベックス形状（横断面が凸状の波線）にすることができる。さらに、複数の振動板２の各々は、少なくとも４個に等分割されるのが好ましい。また、複数のスリット８は、円筒形状に配列された複数の振動板２それぞれの間に設けられ、複数の振動板２を互いに分離させ、複数の振動板２が振動する際に振動板２同士が接触しないように、円筒形弾性体の内周の軸方向に沿って平行に設けられている。また、一対の円筒形振動体３ａ，３ｂは、複数の振動板２の軸方向上下端部に接着され、複数の振動板２により形成された円筒形状配列の中心軸と同軸で、かつ、複数の振動板２の円筒形状配列外周とほぼ同じ外周と、複数の振動板２の円筒形状配列内周よりも小径の内周とを有するが、円筒形状配列の軸方向の中央と両端部との間に設けることもできる。この場合は、複数の振動板２の円筒形状配列の内周が円筒形振動体３ａ，３ｂの外周に等しくなる。円筒形振動体３ａ，３ｂは、入力される電気信号に応じて振動してこの振動を複数の振動板２に伝達する。
【００２７】
また、一対のプレート４０ａ，４０ｂは、複数の振動板２と円筒形振動体３ａ，３ｂとにより形成された円筒形状の軸方向両端部に接着して設けられ、厚み方向の剛性が高く径方向の剛性が低い一方向強度材料を用い、かつ、リード線５を貫通させるための穴を有する。また、リード線２は、外部から円筒形振動体３ａ，３ｂに振動を与えるために、一方のプレート４０ａの一部分から円筒形振動体３ａ，３ｂに電気信号を供給する。リード線５と一対のプレート４０ａ，４０ｂとの境界面には弾性体が充填され、水密保護されている。弾性体としては、合成樹脂を用いるのが好ましい。また、ボルト６及びナット７は、一対のプレート４０ａ，４０ｂのいずれか一方の中心部にボルト６が貫通し、他方の中心部にナット７を配置し、このナット７及びボルト６によって一対のプレート４０ａ，４０ｂを固定し、円筒形状全体を締め付け固定している。従って、一対のプレート４０ａ，４０ｂ間の間隔はほぼ一定である。なお、ボルト６，ナット７は、一対のプレート４０ａ，４０ｂを固定できるならば、単なるシャフトであっても良い。ボルト６及びナット７と、一対のプレート４０ａ，４０ｂとの境界面には、弾性体が充填され、水密保護されている。弾性体は、合成樹脂を用いるのが好ましい。また、絶縁シース１は、複数の振動板２と一対のプレート４０ａ，４０ｂとを被覆するために、一対のプレート４０ａ，４０ｂ及び複数の振動板２によって形成された円筒形状の円周囲に接着剤により密着されている。なお、各分割振動板２間の隙間は小さいので、絶縁シース１を適宜厚くすることにより高耐水圧性の送受波とすることができる。
【００２８】
次に、この例の動作について説明する。
まず、この例における屈曲振動モードの動作について説明する。図２は、この例における屈曲振動モードの動作を示す概略図である。屈曲振動モードは、円筒形振動体３ａ，３ｂが円筒形の軸方向に動き、複数の振動板２が屈曲するモードである。まず、外部からリード線５に電気信号を与え、一対の円筒形振動体３ａ，３ｂを励振させ、機械的振動を発生させる。複数の振動板２と一対の円筒形振動体３ａ，３ｂとは接着固定されており、また、ボルト６とナット７とによって一対のプレート４０ａ，４０ｂの間隔が拘束されているので、一対の円筒形振動体３ａ，３ｂが、上述の機械的振動によって軸方向に縦振動するとき、複数の振動板２と一対の円筒形振動体３ａ，３ｂとの接合面を支点として、一対の円筒形振動体３ａ，３ｂに屈曲振動モードが発生する。このとき、屈曲型送受波器の径方向に屈曲振動モードによる音波放射が行われる。
【００２９】
次に、この例における呼吸振動モードの動作について説明する。図３は、この例における呼吸振動モードの動作を示す概略図である。呼吸振動モードは、円筒形振動体３ａ，３ｂが円筒形の径方向に動き、円筒形振動体３ａ，３ｂと複数の振動板２とが一緒に径方向に動くモードである。まず、一対の円筒形振動体３ａ，３ｂの呼吸振動モードを励起する周波数の電気信号を与えると、一対の円筒形振動体３ａ，３ｂは呼吸振動モードを発生する。一対の円筒形振動体３ａ，３ｂの呼吸振動モードに合わせ、一対の円筒形振動体３ａ，３ｂと複数の振動板２とにより形成される円筒形状全体の呼吸振動モードが励起される。この呼吸振動モードによる共振周波数は、一対の円筒形振動体３ａ，３ｂの形状により、以下の式により決まる。
ｆｒ’＝（１／２πａ）×（Ｅ／ρ）^１／２・・・（２）
ここで、ａ：円筒形振動体３ａ，３ｂの平均半径、Ｅ：円筒形振動体３ａ，３ｂの縦弾性係数、ρ：円筒形振動体３ａ，３ｂの密度である。このとき、一対のプレート４０ａ，４０ｂの径方向の剛性は、一対の円筒形振動体３ａ，３ｂの呼吸振動モード発生力よりも十分弱くなるように設定してあるので、一対の円筒形振動体３ａ，３ｂの呼吸振動モードに合わせ、一対のプレート４０ａ，４０ｂも径方向へ伸縮する。従って、一対のプレート４０ａ，４０ｂが一対の円筒形振動体３ａ，３ｂの呼吸振動モードによる振幅を妨げることはない。このように、この例では、振動板２の屈曲振動モードによる第１のモードに加え、一対の円筒形振動体３ａ，３ｂと複数の振動板２とによる円筒形状全体の呼吸振動による第２のモードとを、近接する周波数で得ることができる。従って、複数の振動板２の屈曲振動モードと、円筒形振動体３ａ，３ｂ及び複数の振動板２の呼吸振動モードとを利用し、低い機械的共振周波数の音波を放射できる周波数帯域を広げることができる。
【００３０】
上述したように、この例では、一対の円筒形振動体３ａ，３ｂが周方向の広がりによる呼吸振動モードを発生させたとき、一対のプレート４０ａ，４０ｂも一対の円筒形振動体３ａ，３ｂの呼吸振動モードに追従し、径広がりを行うため、一対の円筒形振動体３ａ，３ｂの呼吸振動モードの動作を妨げることなく、一対の円筒形振動体３ａ，３ｂと複数の振動板２とで形成する円筒形状全体の呼吸振動モードを得ることができる。従って、図３に示した呼吸振動モードによる共振周波数ｆｒ’を、図２に示したような一対の円筒形振動体３ａ，３ｂの縦振動による複数の振動板２の屈曲振動モードによる共振周波数ｆｒと合わせると、２つの共振周波数が連続し、広い周波数帯域で一定以上の送受波レベルが得られる。
【００３１】
◇第２実施例
次に、この発明の第２実施例について説明する。
まず、この発明の第２実施例の構成について説明する。図４は、この例に係る複合円筒形振動板の構成を示す概略図である。上述した第１実施例では、振動励起の駆動源として一対の円筒形振動体３ａ，３ｂを用いたが、この例では、一対の円筒形振動体３ａ，３ｂの代わりに、一対の複合円筒形振動体５０を用いる。従って、この例は、円筒形弾性体を円周方向に複数に等分割し軸方向に互いに平行に分離して円筒形に配列された複数の振動板２と、複数の振動板２を円筒形の軸方向に等分割する複数のスリット８と、円筒形に配列された複数の振動板２の軸方向両端部に設けられた一対の複合円筒形振動体５０と、一対の複合円筒形振動体５０に電気的信号を与えるために複合円筒形振動体５０に接続されたリード線５と、円筒形全体を覆う絶縁シース１とを備え、一対の複合円筒形振動体５０と絶縁シース１との間に接着して設けられ、一対の複合円筒形振動体５０の外径と同じ外径を有する円形の板により形成され、所定の位置にリード線５を貫通させる穴を有する一対のプレート４０ａ，４０ｂと、一対のプレート４０ａ，４０ｂ間の間隔が一定となるように、一対のプレート４０ａ，４０ｂを固定するボルト６及びナット７とを備え、一対の複合円筒形振動体５０及び複数の振動板２の呼吸振動に合わせて一対のプレート４０ａ，４０ｂを径方向へ伸縮させるために、一対のプレート４０ａ，４０ｂを、厚み方向の剛性が高く、径方向の剛性が低い一方向強度材料より形成している。特に、この例で用いる複合円筒形振動体５０は、円周方向にリング状に並べられた複数のアクティブ振動体９と、複数のアクティブ振動体９の間に配置された周波数調整材２０とを円状に並べ、周囲全体を繊維材１０により締め付け固定した構造である。複数のアクティブ振動体９は、上面から見て矩形状であり、円周方向にリング状に並べると多角形状に配置される。周波数調整材２０は、複数のアクティブ振動体９間に配置され、その密度を変えることにより複合円筒形振動体５０全体の密度を変え、複合円筒形振動体５０による共振周波数を変えることができる。繊維材１０は、複数のアクティブ振動体９及び複数の周波数調整材２０の外周囲を締め付けて固定する。これにより、複数の振動板２が円筒形の径方向に屈曲することにより生じる屈曲振動と、一対の複合円筒形振動体５０及び複数の振動板２が円筒形の径方向に移動することにより生じる呼吸振動とにより、音響管を構成し、水中に音波放射する屈曲型送受波器である。
【００３２】
次に、この例の動作について説明する。
まず、この例における屈曲振動モードについて説明する。外部からリード線５に電気信号を与え、一対の複合円筒形振動体５０を励振させ、機械的振動を発生させる。複数の振動板２と一対の複合円筒形振動体５０とは接着固定されており、また、ボルト６とナット７とによって一対のプレート４０ａ，４０ｂの間隔が拘束されているので、一対の複合円筒形振動体５０が、上述の機械的振動によって縦振動するとき、複数の振動板２と一対の複合円筒形振動体５０との接合面を支点として、一対の複合円筒形振動体５０に屈曲振動モードが発生する。このとき、屈曲型送受波器の径方向に屈曲振動モードによる音波放射が行われる。
【００３３】
次に、この例における呼吸振動モードの動作について説明する。まず、一対の複合円筒形振動体５０の呼吸振動モードを励起する周波数の電気信号を与えると、一対の複合円筒形振動体５０は呼吸振動モードを発生する。一対の複合円筒形振動体５０の呼吸振動モードに合わせ、一対の複合円筒形振動体５０と複数の振動板２とにより形成される円筒形状全体の呼吸振動モードが励起される。この呼吸振動モードによる共振周波数は、上述した式（２）で得られる。ここで、複合円筒形振動体５０の周波数調整材２０の密度を大きくしていき、複合円筒形振動体５０全体としてのρ（密度）を増加させる。このようにして、ρ（密度）を調整し、式（２）で得られる円筒形状の呼吸振動モードによる共振周波数ｆｒ’を、振動板２の屈曲振動モードによる共振周波数ｆｒに近づける。２つの機械的共振モードによる共振周波数ｆｒ，ｆｒ’を近づけていくと、２つの周波数帯が重畳し、一定以上のレベルが得られる周波数帯域幅を広げることができる。周波数調整材２０の密度の調整は、材料を変えることにより調整することができる。
【００３４】
上述したように、この発明の第２実施例では、周波数調整材２０の密度を変えることにより複合円筒形振動体５０の呼吸振動モードによる共振周波数ｆｒ’を下げることができ、振動板２の屈曲振動モードによる共振周波数ｆｒに近づけることができる。
【００３５】
図５は、この発明の実施例である屈曲型送受波器に係る送波レベル−周波数特性を示すグラフである。実線は従来例に係る送波レベル−周波数特性を示し、点線はこの発明に係る送波レベル−周波数特性を示している。この送波レベル−周波数特性は、図５の実線で示した従来例では、一定以上の送波レベルが得られる周波数は、屈曲振動モードによる共振周波数ｆｒのみであるが、この発明によると、図２に示す振動板２の屈曲振動モードによる共振周波数ｆｒと、図３に示す円筒形状の呼吸振動モードによる共振周波数ｆｒ’という２つの共振周波数により、図５の点線で示すような、一定以上の送波レベルを得られる周波数帯が２つ得られる。
【００３６】
図６は、図５と同様に、この発明の実施例である屈曲型送受波器に係る送波レベル−周波数特性を示すグラフであるが、図５と比較すると、２つの周波数がより近づいたときのグラフである。円筒形振動子２の円筒形状の径寸法を大きくしていくと、式（２）から呼吸振動モードによる共振周波数ｆｒ’が低下していき、屈曲振動モードによる共振周波数ｆｒに近づき、２つの共振周波数ｆｒとｆｒ’とが近づくことによって、２つの周波数帯が重畳し、図６に示すように、一定以上の送波レベルが得られる周波数帯域幅が広がる。図６では、この一定以上の送波レベルを「所要レベル」として示している。すなわち、図６では、屈曲振動モードによる共振周波数ｆｒと呼吸振動モードによる共振周波数ｆｒ’とは連続して所要レベル以上の値の送波レベルであることを示している。
【００３７】
以上、この発明の実施例について詳述してきたが、具体的な構成はこの実施例に限られるものではなく、この発明の趣旨を逸脱しない設計の変更等があってもこの発明に含まれる。
例えば、上述した実施例においては、複数の振動板２を円筒形状に配列するとしたが、これに限らず、必要に応じて多角形状に配列しても良い。
【００３８】
また、上述した実施例においては、円筒形の振動板２を必要に応じて、その断面がフラット形状，コンケーブ形状，コンベックス形状にしても構わないとしたが、これに限らず、これら以外の波状で構成しても良いし、ランダムな形状で構成にしても良い。
【００３９】
また、上述した実施例においては、複合円筒形振動体５０のアクティブ振動体９及び周波数調整材２０の周囲を繊維材１０により締め付け固定した構成であるが、これに限らず、複合円筒形振動体５０として、その他の構成要素を付加しても良い。
【００４０】
また、上述した実施例においては、複合円筒形振動体５０のアクティブ振動体９は、矩形としたが、これに限らず、その役目を果たすものなら、対向する辺を曲線で形成しても良いし、他の形状にしても良い。
【００４１】
また、上述した実施例においては、複合円筒形振動体５０の繊維材１０は、繊維だけでなく、他の材料、例えば、合成樹脂よりなる弾性体で構成しても良い。
【００４２】
また、上述した実施例においては、一対のプレート４０ａ，４０ｂとボルト６又はナット７との境界部は、合成樹脂が充填され、水密保護される構成にしたが、これに限らず、水密保護できれば合成樹脂以外の材料により構成しても良い。
【００４３】
【発明の効果】
以上説明したように、この発明の構成によれば、振動板の屈曲振動モードによる第１のモードに加え、一対の円筒形振動体（あるいは、複合円筒形振動体）と振動板とによる円筒形状全体の呼吸振動による第２のモードを、近接する周波数で得ることができるので、複数の振動板の屈曲振動モードと円筒の呼吸振動モードとを利用し、低い機械的共振周波数の音波放射できる屈曲型送受波器の周波数帯域を広げることができる。
【図面の簡単な説明】
【図１】この発明の第１実施例である屈曲型送受波器の構成を示す概略図である。
【図２】この発明の第１実施例である屈曲型送受波器の動作（屈曲振動モード）を示す概略図である。
【図３】この発明の第１実施例である屈曲型送受波器の動作（呼吸振動モード）を示す概略図である。
【図４】この発明の第２実施例である屈曲型送受波器に係る複合円筒形振動体の構造を示す概略図である。
【図５】この発明の実施例である屈曲型送受波器に係る送波レベル周波数特性の一例を示すグラフである。
【図６】この発明の実施例である屈曲型送受波器に係る送波レベル周波数特性の一例を示すグラフである。
【図７】従来の屈曲型送受波器の構成を示す概略図である。
【図８】従来の屈曲型送受波器の動作を示す概略図である。
【符号の説明】
１絶縁シース
２振動板
２ａ屈曲振動モード
２ｂ呼吸振動モード
３ａ，３ｂ円筒形振動体
４ａ，４ｂ支持リング（従来例）
５リード線
６ボルト
７ナット
８スリット
９アクティブ振動体
１０繊維材
２０周波数調整材
４０ａ，４０ｂプレート
５０複合円筒形振動体[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electroacoustic transducer that radiates sound waves into water, and more particularly, to a flexural transducer that radiates sound waves into water by bending vibration of a plurality of diaphragms arranged in a cylindrical shape.
[0002]
[Prior art]
Conventionally, this type of bending transducer has a structure in which a cylindrical vibrator is laminated as an electrical / mechanical conversion element, an insulating sheath is provided on the outer surface or inner surface of the cylindrical vibrator, and transmission / reception is performed via a lead wire. In order to obtain a high transmission sound pressure, the transmission frequency has been set using the resonance in the breathing vibration mode of the cylindrical vibrator. However, this type of transducer has a high resonance frequency due to the breathing vibration mode due to the high rigidity of the cylindrical vibrator. Conversely, if the resonance frequency due to the breathing vibration mode is reduced, the outer diameter of the entire device is reduced. There is a drawback that becomes larger.
[0003]
For this reason, in order to obtain a small and lightweight transducer at a low frequency, the vibration of the cylindrical vibrator and the supporting force of the support ring that provides a fulcrum for the cylindrical vibrator are bent by the diaphragm. In addition to causing resonance, it is necessary to construct an acoustic tube in the inner space of the diaphragm and delay the inner surface radiated sound wave of the diaphragm to superimpose substantially the same phase and the outer surface radiated sound wave. That is, by utilizing the flexural vibration mode of a plurality of diaphragms provided in the axial direction of the cylindrical shape and lowering the resonance frequency of this flexural vibration mode, the sound wave of the frequency can be reduced with a small and light flexural transducer. To get.
[0004]
As an example of the above-described conventional example, for example, there is a transducer (hereinafter referred to as a first conventional example) disclosed in JP-A-2-309799. Hereinafter, the first conventional example will be described.
First, the configuration of this conventional example will be described. FIG. 7 is a schematic diagram showing the configuration of the above-described bent type transducer of the first conventional example. In this example, for example, eight diaphragms 2 are arranged on the circumference of the cylindrical vibrators 3a and 3b, and support rings are attached to upper and lower ends so that the arranged eight diaphragms 2 are fixed. 4a and 4b are provided, and the entire outer periphery thereof is covered with the outer sheet 1 and has a watertight protection structure. However, the sound wave generated by the vibration of the diaphragm 2 is inverted in phase on the inner and outer surfaces of the diaphragm 2, and the inner surface radiated sound wave is directly superimposed on the outer surface radiated sound wave. Resulting in. For this reason, in order to avoid this short circuit phenomenon, the phase of the inner surface radiated sound wave of the vibrator 2 is configured to match the phase of the outer surface radiated sound wave.
[0005]
Next, the operation of this conventional example will be described. FIG. 8 is a partial sectional view showing a part of a longitudinal section of the above-described bent type transducer of the first conventional example. First, when an electrical signal having the same frequency as the mechanical resonance frequency (fr) generated in the bending vibration mode of the diaphragm 2 is applied to the cylindrical vibrators 3a and 3b via the lead wire 5, the cylindrical vibrators 3a and 3b A radial vibration is generated, and a bending vibration mode of the diaphragm 2 using the support rings 4a and 4b as fulcrums is generated by the radial vibration. Due to the mechanical resonance in this bending vibration mode, a low-frequency sound output can be obtained. The mechanical resonance frequency fr is such that the length of the diaphragm 2 is L (cm), the thickness is t (cm), and the longitudinal elastic modulus is E (kg / cm).² ), The density is ρ (kg / cm³ ), When the Poisson's ratio is α and the dimensionless coefficient determined by the vibration system is σ, it is simply expressed by the following equation.
fr = απt / 2L² {E / 3 (1-σ² ) Ρ}^1/2 ... (1)
That is, the mechanical resonance frequency fr is determined to be one value depending on the material and dimensions of the diaphragm 2.
[0006]
Therefore, in the first conventional apparatus, although it is possible to perform low-frequency acoustic radiation with a small and light bending transducer, as described above, it is mechanically dependent on the bending vibration mode of the constituting diaphragm. The resonance frequency fr is determined to be one value depending on the material and dimensions of the diaphragm, and the frequency band in which a transmission / reception level exceeding a certain level is obtained is narrow.
[0007]
Therefore, in order to obtain a low frequency as described above, in order to widen the frequency band where a transmission level above a certain level can be obtained, the cylindrical vibrator performs respiratory vibration and applies a driving force in the radial direction to the dividing plate. As an example, there is an ultrasonic transducer described in Japanese Patent Application Laid-Open No. 09-037379 and a manufacturing method thereof (hereinafter referred to as a second conventional example). In a second conventional example, in a ring-shaped or cylindrical piezoelectric vibrator made of piezoelectric ceramic, a surface in which hole groups are distributed is in a plane perpendicular to the cylindrical axis direction of the cylindrical diameter. In the surface of the piezoelectric vibrator having a cylindrical diameter, the piezoelectric vibrator is formed at a plurality of locations at a pitch of 1/3 or less of the thickness. Such a hole group has a function of reducing the Young's modulus of the piezoelectric vibrator and reducing the coupling of resonance modes other than the thickness direction. When a high voltage is applied to the inner surface electrode and the outer surface electrode, the piezoelectric vibrator However, thickness vibration is performed in an annular shape polarized in the thickness direction, and cylindrical waves are radiated.
[0008]
[Problems to be solved by the invention]
However, even in the second conventional apparatus, a group of piezoelectric ceramic holes is formed instead of the groove, and the Young's modulus of the piezoelectric vibrator is lowered by the hole group, so that the cylindrical vibrator performs a respiration motion. It is necessary to pay close attention to the manufacturing method of the piezoelectric ceramic, and the piezoelectric vibrator forming process, firing process, electrode forming process and manufacturing method are very complicated. Furthermore, in order to manufacture the target transducer, there is a problem that a considerable size is required.
[0009]
The present invention has been made in view of the above-described circumstances, and uses a flexural vibration mode of a diaphragm that achieves a small size and a low frequency, and is capable of obtaining a certain level or more of a transmission level in a wide frequency band. The purpose is to provide a waver.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention described in claim 1 includes a plurality of diaphragms arranged in a cylindrical shape by equally dividing a cylindrical elastic body into a plurality of parts in the circumferential direction and separating them in parallel in the axial direction. A plurality of slits for equally dividing the plurality of diaphragms in a cylindrical axial direction; a pair of cylindrical vibrators provided at both axial ends of the plurality of diaphragms arranged in the cylindrical shape; A lead wire connected to the cylindrical vibrator for providing an electrical signal to a pair of cylindrical vibrators, and an insulating sheath covering the entire cylindrical shape, wherein the plurality of diaphragms have a diameter of the cylindrical shape. Radiates sound waves into the water by resonance between bending vibration generated by bending in the direction and respiratory vibration generated by the pair of cylindrical vibrators and the plurality of diaphragms moving in the radial direction of the cylinder. A flexural transducer,
The lead is provided between the pair of cylindrical vibrators and the insulating sheath, and is formed by a circular plate having the same outer diameter as the pair of cylindrical vibrators. A pair of plates having a hole through which a wire passes, and a bolt and a nut for fixing the pair of plates so that a distance between the pair of plates is constant, and the pair of cylindrical vibrators and the above In order to expand and contract the pair of plates in the radial direction in accordance with respiratory vibrations of a plurality of diaphragms, the pair of plates is made of a unidirectional strength material having relatively high thickness rigidity and relatively low radial rigidity. It is characterized by being formed more.
[0011]
The invention according to claim 2 relates to the bending transducer according to claim 1, wherein the frequency of the sound wave due to the respiratory vibration is changed to the frequency of the sound wave due to the bending vibration by the unidirectional strength material of the pair of plates. The sound wave frequency of the respiratory vibration is superimposed on the frequency of the sound wave of the flexural vibration to obtain a transmission / reception level above a certain level, and a sound wave having a low mechanical resonance frequency can be emitted in a wide frequency band. Yes.
[0012]
A third aspect of the present invention relates to the bent transducer according to the first or second aspect, wherein the pair of cylindrical vibrators includes a central axis of a cylindrical array formed by the plurality of diaphragms. It is coaxial, and has an outer periphery that is substantially the same as the outer periphery of the cylindrical array of the plurality of diaphragms, and an inner periphery that is smaller in diameter than the inner periphery of the cylindrical array of the plurality of diaphragms.
[0013]
According to a fourth aspect of the present invention, there is provided the flexural transducer according to the first or second aspect, wherein the pair of cylindrical vibrators have an outer diameter equal to an inner diameter of a cylindrical arrangement of the plurality of diaphragms. Each of the plurality of diaphragms is provided between an axial center and both ends of the cylindrical array.
[0014]
Further, the invention according to claim 5 relates to the bending transducer according to any one of claims 1 to 4, wherein a bolt penetrates through a central portion of one of the pair of plates, The pair of plates is fixed by tightening a bolt with a nut disposed at the center of the other plate.
[0015]
According to a sixth aspect of the present invention, there is provided the flexural transducer according to any one of the first to fifth aspects, wherein an elastic body is provided at a boundary surface between the pair of plates and the bolts and nuts. It is filled and watertight protected.
[0016]
According to a seventh aspect of the present invention, there is provided the bending type transducer according to the sixth aspect, wherein the elastic body is a synthetic resin.
[0017]
The invention according to claim 8 relates to the bending transducer according to any one of claims 1 to 7, wherein the pair of cylindrical vibrators are arranged in a ring shape in the circumferential direction. Active vibrators, a plurality of frequency adjusting materials disposed between the plurality of active vibrating bodies, and a fiber material for fastening and fixing the outer peripheries of the plurality of active vibrating bodies and the plurality of frequency adjusting materials. It is characterized by having a pair of composite cylindrical vibrators.
[0018]
The invention according to claim 9 relates to the bending transducer according to claim 8, wherein each of the plurality of active vibrators is a cylinder or a prism.
[0019]
Further, the invention according to claim 10 relates to the bending transducer according to claim 8 or 9, wherein by adjusting the density of the frequency adjusting material, the pair of composite cylindrical vibrators in the radial direction is respired. It is characterized by adjusting the frequency of sound waves caused by vibration.
[0020]
An eleventh aspect of the present invention relates to the flexural transducer according to the tenth aspect, and by increasing the density of the frequency adjusting material, the frequency due to the respiratory vibration is lowered and the sound wave due to the flexural vibration is reduced. It is characterized by being close to the frequency.
[0021]
A twelfth aspect of the present invention relates to the flexural transducer according to the eleventh aspect of the present invention, in which a frequency band of sound waves generated by the respiratory vibration and a frequency band of sound waves generated by the bent vibration are superimposed, and a wide resonance frequency bandwidth is obtained. It is characterized in that a transmission level above a certain level can be obtained.
[0022]
As described above, according to the first means of the present invention, the unidirectional reinforcing material having high rigidity in the longitudinal direction of the cylindrical shape and low rigidity in the radial direction of the cylindrical shape on the upper and lower end surfaces of the bending type transducer. The plate formed by the above is arranged, and the plate is fastened and fixed by bolts and nuts.
[0023]
Further, according to the second means of the present invention, in the bending type transducer having the first means, the cylindrical vibrator is arranged with the active vibrator and the frequency adjusting material arranged in a circle, and the outer periphery thereof is wound by the fiber material. A composite cylindrical vibrator formed in a cylindrical shape is used.
[0024]
[Action]
In the first means, when the cylindrical vibrating body generates a breathing vibration mode by spreading in the circumferential direction, the plate also expands following the breathing vibration mode of the cylindrical vibrating body. The respiration vibration mode of the entire cylindrical shape formed by the cylindrical vibration body and the diaphragm can be obtained without hindering the operation of the respiration vibration mode. Accordingly, two resonance frequencies can be realized together with the resonance frequency of the vibration plate bending vibration mode generated by the longitudinal vibration of the cylindrical vibrator.
In the second means, the resonance frequency by the breathing vibration mode of the composite cylindrical vibrator can be lowered by the frequency adjusting material, and the resonance frequency by the breathing vibration mode is brought close to the resonance frequency by the bending vibration mode of the diaphragm. Can do.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The description will be made specifically with reference to examples.
◇ First example
First, the configuration of the first embodiment of the present invention will be described.
FIG. 1 is a schematic diagram showing the configuration of a bent transducer according to the first embodiment of the present invention. In this example, a cylindrical elastic body is equally divided into a plurality of parts in the circumferential direction and separated in parallel to each other in the axial direction, and a plurality of diaphragms 2 are arranged in a cylindrical shape, and the plurality of diaphragms 2 are arranged in a cylindrical axis A plurality of slits 8 equally divided in the direction, a pair of cylindrical vibrators 3a, 3b provided at both axial ends of the plurality of diaphragms 2 arranged in a cylindrical shape, and a pair of cylindrical vibrators 3a, In order to give an electrical signal to 3b, a lead wire 5 connected to the cylindrical vibrators 3a and 3b and an insulating sheath 1 covering the entire cylindrical shape are provided. In particular, in this example, a circular shape that is provided between the pair of cylindrical vibrators 3a and 3b and the insulating sheath 1 and has the same outer diameter as that of the pair of cylindrical vibrators 3a and 3b. The pair of plates 40a and 40b, which are formed of a plurality of plates and have holes through which the lead wires 5 penetrate at predetermined positions, and the pair of plates 40a and 40b are fixed so that the distance between the pair of plates 40a and 40b is constant. A bolt 6 and a nut 7 for fixing are provided, and a pair of plates 40a and 40b are expanded and contracted in the radial direction in accordance with the respiratory vibration of the pair of cylindrical vibrators 3a and 3b and the plurality of diaphragms 2. 40a and 40b are characterized by being formed of a unidirectional strength material having a high rigidity in the thickness direction and a low rigidity in the radial direction. As a result, bending vibration generated when the plurality of diaphragms 2 are bent in the cylindrical radial direction, and the pair of cylindrical vibrators 3a and 3b and the plurality of diaphragms 2 move in the cylindrical radial direction. It is a bending type transducer that constitutes an acoustic tube and emits sound waves in water by the generated respiratory vibration.
[0026]
Next, the detailed configuration of each part in this example will be described. The plurality of diaphragms 2 are formed in a cylindrical shape by an elastic body such as metal or synthetic resin, and are substantially equally divided into a plurality by slits 8 provided in parallel to the axial direction of the inner periphery of the cylindrical elastic body. And arranged separately from each other. In addition, the axial dimension of the cylindrical array of the plurality of diaphragms 2 is set between approximately one half wavelength and one wavelength of the sound wave, and the sound waves can be radiated into water by the bending vibration of the plurality of diaphragms 2. In addition, the plurality of diaphragms 2 are arranged in a cylindrical shape (circular cross section is circular) here, but the shape may be a flat shape (transverse cross section is a polygon), a cape shape (transverse cross section) as necessary. The surface may be a concave wavy line) or a convex shape (a wavy line having a convex cross section). Furthermore, each of the plurality of diaphragms 2 is preferably equally divided into at least four. The plurality of slits 8 are provided between each of the plurality of diaphragms 2 arranged in a cylindrical shape, separate the plurality of diaphragms 2 from each other, and the diaphragms 2 vibrate when the plurality of diaphragms 2 vibrate. Are provided in parallel along the axial direction of the inner periphery of the cylindrical elastic body. The pair of cylindrical vibrators 3 a and 3 b are bonded to the upper and lower ends in the axial direction of the plurality of diaphragms 2, are coaxial with the central axis of the cylindrical array formed by the plurality of diaphragms 2, and The outer periphery of the diaphragm 2 is substantially the same as the outer periphery of the cylindrical array and the inner periphery of the plurality of diaphragms 2 is smaller in diameter than the inner periphery of the cylindrical array. It can also be provided in between. In this case, the inner circumference of the cylindrical array of the plurality of diaphragms 2 is equal to the outer circumference of the cylindrical vibrators 3a and 3b. The cylindrical vibrators 3 a and 3 b vibrate according to the input electric signal and transmit this vibration to the plurality of diaphragms 2.
[0027]
The pair of plates 40a and 40b are provided by being bonded to both ends of the cylindrical axial direction formed by the plurality of diaphragms 2 and the cylindrical vibrating bodies 3a and 3b, and have a high rigidity in the thickness direction and a radial direction. The unidirectional strength material having a low rigidity is used, and a hole for penetrating the lead wire 5 is provided. Further, the lead wire 2 supplies an electrical signal to the cylindrical vibrators 3a and 3b from a part of one plate 40a in order to apply vibration to the cylindrical vibrators 3a and 3b from the outside. The boundary surface between the lead wire 5 and the pair of plates 40a and 40b is filled with an elastic body to be watertight protected. As the elastic body, it is preferable to use a synthetic resin. Further, the bolt 6 and the nut 7 are arranged such that the bolt 6 passes through the central portion of one of the pair of plates 40a and 40b, and the nut 7 is disposed at the other central portion. 40a and 40b are fixed, and the whole cylindrical shape is fastened and fixed. Accordingly, the distance between the pair of plates 40a and 40b is substantially constant. The bolts 6 and nuts 7 may be simple shafts as long as the pair of plates 40a and 40b can be fixed. The boundary surface between the bolt 6 and the nut 7 and the pair of plates 40a and 40b is filled with an elastic body to be watertight protected. It is preferable to use a synthetic resin for the elastic body. Further, the insulating sheath 1 has an adhesive around a cylindrical circle formed by the pair of plates 40a, 40b and the plurality of diaphragms 2 in order to cover the plurality of diaphragms 2 and the pair of plates 40a, 40b. Is closely attached. In addition, since the clearance gap between each division | segmentation diaphragm 2 is small, it can be set as the high water-pressure-resistant transmission / reception wave by thickening the insulation sheath 1 suitably.
[0028]
Next, the operation of this example will be described.
First, the bending vibration mode operation in this example will be described. FIG. 2 is a schematic diagram showing the operation in the bending vibration mode in this example. The bending vibration mode is a mode in which the cylindrical vibrating bodies 3a and 3b move in the axial direction of the cylinder and the plurality of diaphragms 2 are bent. First, an electrical signal is applied to the lead wire 5 from the outside, and the pair of cylindrical vibrators 3a and 3b are excited to generate mechanical vibration. The plurality of diaphragms 2 and the pair of cylindrical vibrators 3a and 3b are bonded and fixed, and the distance between the pair of plates 40a and 40b is constrained by the bolt 6 and the nut 7, so that the pair of cylinders When the shape vibrating bodies 3a and 3b longitudinally vibrate in the axial direction due to the mechanical vibration described above, a pair of cylindrical vibrations with the joint surfaces of the plurality of diaphragms 2 and the pair of cylindrical vibration bodies 3a and 3b as fulcrums. A bending vibration mode is generated in the bodies 3a and 3b. At this time, sound wave emission in the bending vibration mode is performed in the radial direction of the bending transducer.
[0029]
Next, the operation in the respiratory vibration mode in this example will be described. FIG. 3 is a schematic view showing the operation in the respiratory vibration mode in this example. The breathing vibration mode is a mode in which the cylindrical vibrators 3a and 3b move in the radial direction of the cylinder, and the cylindrical vibrators 3a and 3b and the plurality of diaphragms 2 move in the radial direction together. First, when an electrical signal having a frequency for exciting the respiratory vibration mode of the pair of cylindrical vibrators 3a and 3b is given, the pair of cylindrical vibrators 3a and 3b generate a respiratory vibration mode. In accordance with the breathing vibration mode of the pair of cylindrical vibrators 3a, 3b, the breathing vibration mode of the entire cylindrical shape formed by the pair of cylindrical vibrators 3a, 3b and the plurality of diaphragms 2 is excited. The resonance frequency in this breathing vibration mode is determined by the following equation depending on the shape of the pair of cylindrical vibrators 3a and 3b.
fr ′ = (1 / 2πa) × (E / ρ)^1/2 ... (2)
Here, a is the average radius of the cylindrical vibrators 3a and 3b, E is the longitudinal elastic modulus of the cylindrical vibrators 3a and 3b, and ρ is the density of the cylindrical vibrators 3a and 3b. At this time, the radial rigidity of the pair of plates 40a and 40b is set to be sufficiently weaker than the respiratory vibration mode generation force of the pair of cylindrical vibrators 3a and 3b. The pair of plates 40a and 40b expands and contracts in the radial direction in accordance with the respiratory vibration mode 3a and 3b. Therefore, the pair of plates 40a and 40b does not hinder the amplitude of the pair of cylindrical vibrators 3a and 3b due to the respiratory vibration mode. As described above, in this example, in addition to the first mode based on the flexural vibration mode of the diaphragm 2, the second cylindrical vibration body 3 a, 3 b and a plurality of diaphragms 2, which are caused by respiratory vibration of the entire cylindrical shape. Modes can be obtained at close frequencies. Therefore, by using the flexural vibration mode of the plurality of diaphragms 2 and the respiratory vibration modes of the cylindrical vibrators 3a and 3b and the plurality of diaphragms 2, the frequency band in which sound waves having a low mechanical resonance frequency can be radiated is widened. Can do.
[0030]
As described above, in this example, when the pair of cylindrical vibrators 3a and 3b generate a breathing vibration mode due to the spread in the circumferential direction, the pair of plates 40a and 40b is also the pair of cylindrical vibrators 3a and 3b. In order to follow the respiratory vibration mode and expand the diameter, the pair of cylindrical vibrators 3a and 3b and the plurality of diaphragms 2 can be used without interfering with the operation of the pair of cylindrical vibrators 3a and 3b in the respiratory vibration mode. The breathing vibration mode of the whole cylindrical shape to be formed can be obtained. Therefore, the resonance frequency fr ′ according to the respiratory vibration mode shown in FIG. 3 is changed to the resonance frequency fr according to the bending vibration mode of the plurality of diaphragms 2 due to the longitudinal vibration of the pair of cylindrical vibrators 3a and 3b as shown in FIG. In combination, two resonance frequencies are continuous, and a certain level of transmission and reception waves can be obtained in a wide frequency band.
[0031]
◇ Second embodiment
Next explained is the second embodiment of the invention.
First, the configuration of the second embodiment of the present invention will be described. FIG. 4 is a schematic view showing the configuration of the composite cylindrical diaphragm according to this example. In the first embodiment described above, a pair of cylindrical vibrators 3a and 3b is used as a drive source for vibration excitation. In this example, instead of the pair of cylindrical vibrators 3a and 3b, a pair of composite cylindrical bodies is used. The vibrating body 50 is used. Therefore, in this example, the cylindrical elastic body is equally divided into a plurality in the circumferential direction and separated in parallel with each other in the axial direction, and the plurality of diaphragms 2 are arranged in a cylindrical shape. A plurality of slits 8 equally divided in the axial direction, a pair of composite cylindrical vibrators 50 provided at both axial ends of the plurality of diaphragms 2 arranged in a cylindrical shape, and a pair of composite cylindrical vibrators A lead wire 5 connected to the composite cylindrical vibrator 50 to provide an electrical signal to the power source 50 and an insulating sheath 1 covering the entire cylindrical shape, and a pair of the composite cylindrical vibrator 50 and the insulating sheath 1. A pair of plates 40a, which are provided by being bonded to each other and formed by a circular plate having the same outer diameter as that of the pair of composite cylindrical vibrators 50, and having a hole through which the lead wire 5 penetrates at a predetermined position. 40b and the distance between the pair of plates 40a, 40b is constant. As shown in the figure, a bolt 6 and a nut 7 for fixing the pair of plates 40a and 40b are provided, and the pair of plates 40a and 40b have a diameter corresponding to the respiratory vibration of the pair of composite cylindrical vibrators 50 and the plurality of diaphragms 2. In order to expand and contract in the direction, the pair of plates 40a and 40b is formed of a unidirectional strength material having high rigidity in the thickness direction and low rigidity in the radial direction. In particular, the composite cylindrical vibrator 50 used in this example includes a plurality of active vibrators 9 arranged in a ring shape in the circumferential direction, and a frequency adjusting material 20 disposed between the plurality of active vibrators 9. This is a structure in which the entire periphery is fastened and fixed by the fiber material 10 in a circular shape. The plurality of active vibrators 9 have a rectangular shape when viewed from above, and are arranged in a polygonal shape when arranged in a ring shape in the circumferential direction. The frequency adjusting material 20 is disposed between the plurality of active vibrators 9, and the density of the composite cylindrical vibrator 50 can be changed by changing the density thereof, and the resonance frequency of the composite cylindrical vibrator 50 can be changed. The fiber material 10 fastens and fixes the outer peripheries of the plurality of active vibrators 9 and the plurality of frequency adjusting materials 20. As a result, bending vibration generated when the plurality of diaphragms 2 bend in the cylindrical radial direction, and a pair of composite cylindrical vibrators 50 and the plurality of diaphragms 2 move in the cylindrical radial direction. It is a bending type transducer that constitutes an acoustic tube by breathing vibration and emits sound waves in water.
[0032]
Next, the operation of this example will be described.
First, the bending vibration mode in this example will be described. An electric signal is applied to the lead wire 5 from the outside to excite the pair of composite cylindrical vibrators 50 to generate mechanical vibration. The plurality of diaphragms 2 and the pair of composite cylindrical vibrators 50 are bonded and fixed, and the distance between the pair of plates 40a and 40b is constrained by the bolt 6 and the nut 7, so that the pair of composite cylinders When the vibrator 50 vibrates longitudinally due to the mechanical vibration described above, bending vibration occurs in the pair of composite cylindrical vibrators 50 using the joint surfaces of the plurality of diaphragms 2 and the pair of composite cylindrical vibrators 50 as fulcrums. A mode occurs. At this time, sound wave emission in the bending vibration mode is performed in the radial direction of the bending transducer.
[0033]
Next, the operation in the respiratory vibration mode in this example will be described. First, when an electrical signal having a frequency for exciting the breathing vibration mode of the pair of composite cylindrical vibrators 50 is given, the pair of composite cylindrical vibrators 50 generate the breathing vibration mode. In accordance with the breathing vibration mode of the pair of composite cylindrical vibrators 50, the entire cylindrical breathing vibration mode formed by the pair of composite cylindrical vibrators 50 and the plurality of diaphragms 2 is excited. The resonance frequency in this breathing vibration mode is obtained by the above-described equation (2). Here, the density of the frequency adjusting material 20 of the composite cylindrical vibrator 50 is increased to increase the ρ (density) of the composite cylindrical vibrator 50 as a whole. In this way, ρ (density) is adjusted, and the resonance frequency fr ′ obtained by the cylindrical respiratory vibration mode obtained by the equation (2) is made closer to the resonance frequency fr obtained by the bending vibration mode of the diaphragm 2. When the resonance frequencies fr and fr 'by the two mechanical resonance modes are made closer, the two frequency bands are superimposed, and the frequency bandwidth in which a certain level or more can be obtained can be widened. The density of the frequency adjusting material 20 can be adjusted by changing the material.
[0034]
As described above, in the second embodiment of the present invention, by changing the density of the frequency adjusting material 20, the resonance frequency fr ′ due to the respiratory vibration mode of the composite cylindrical vibrating body 50 can be lowered, and the bending of the diaphragm 2 The resonance frequency fr can be brought close to the vibration mode.
[0035]
FIG. 5 is a graph showing a transmission level-frequency characteristic according to the bent transducer according to the embodiment of the present invention. The solid line shows the transmission level-frequency characteristic according to the conventional example, and the dotted line shows the transmission level-frequency characteristic according to the present invention. In the conventional example shown by the solid line in FIG. 5, the transmission level-frequency characteristic is obtained only by the resonance frequency fr in the flexural vibration mode. The resonance frequency fr of the diaphragm 2 shown in FIG. 2 by the flexural vibration mode and the resonance frequency fr ′ of the cylindrical respiratory vibration mode shown in FIG. Two frequency bands from which the transmission level can be obtained are obtained.
[0036]
FIG. 6 is a graph showing the transmission level-frequency characteristics of the bent transducer according to the embodiment of the present invention, as in FIG. 5, but the two frequencies are closer to each other as compared with FIG. It is a graph of time. As the diameter of the cylindrical shape of the cylindrical vibrator 2 is increased, the resonance frequency fr ′ in the breathing vibration mode decreases from the equation (2), approaches the resonance frequency fr in the bending vibration mode, and two resonances occur. By approaching the frequencies fr and fr ′, the two frequency bands are superimposed, and as shown in FIG. 6, the frequency bandwidth in which a transmission level of a certain level or more can be obtained is widened. In FIG. 6, the transmission level above a certain level is shown as “required level”. That is, FIG. 6 shows that the resonance frequency fr in the flexural vibration mode and the resonance frequency fr ′ in the breathing vibration mode are continuously at a transmission level that is equal to or higher than a required level.
[0037]
The embodiment of the present invention has been described in detail above, but the specific configuration is not limited to this embodiment, and design changes and the like that do not depart from the spirit of the present invention are included in the present invention.
For example, in the above-described embodiment, the plurality of diaphragms 2 are arranged in a cylindrical shape, but the present invention is not limited to this and may be arranged in a polygonal shape as necessary.
[0038]
In the above-described embodiment, the cylindrical diaphragm 2 may have a flat shape, a concave shape, or a convex shape as necessary, but the present invention is not limited to this, and the corrugated shape is not limited thereto. It may be configured with a random shape.
[0039]
In the above-described embodiment, the periphery of the active vibration body 9 and the frequency adjusting material 20 of the composite cylindrical vibration body 50 is fastened and fixed by the fiber material 10. As 50, other components may be added.
[0040]
In the above-described embodiment, the active vibrating body 9 of the composite cylindrical vibrating body 50 is rectangular. However, the present invention is not limited to this, and the opposing sides may be formed by curves as long as they play the role. However, other shapes may be used.
[0041]
Further, in the above-described embodiment, the fiber material 10 of the composite cylindrical vibrator 50 may be composed of not only fibers but also other materials, for example, an elastic body made of synthetic resin.
[0042]
In the above-described embodiment, the boundary portion between the pair of plates 40a and 40b and the bolt 6 or the nut 7 is filled with synthetic resin and is watertight protected. You may comprise with materials other than a synthetic resin.
[0043]
【The invention's effect】
As described above, according to the configuration of the present invention, in addition to the first mode based on the flexural vibration mode of the diaphragm, a cylindrical shape including a pair of cylindrical vibrators (or composite cylindrical vibrators) and the diaphragm. Since the second mode due to the whole breathing vibration can be obtained at a close frequency, the bending that can emit sound waves with a low mechanical resonance frequency by using the bending vibration mode of the plurality of diaphragms and the breathing vibration mode of the cylinder. The frequency band of the type transducer can be expanded.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the configuration of a bent transducer according to a first embodiment of the present invention.
FIG. 2 is a schematic diagram showing the operation (flexural vibration mode) of the bending transducer according to the first embodiment of the present invention.
FIG. 3 is a schematic diagram showing the operation (breathing vibration mode) of the bending transducer according to the first embodiment of the present invention.
FIG. 4 is a schematic view showing a structure of a composite cylindrical vibrator according to a bent transducer according to a second embodiment of the present invention.
FIG. 5 is a graph showing an example of a transmission level frequency characteristic according to a bent transducer according to an embodiment of the present invention.
FIG. 6 is a graph showing an example of a transmission level frequency characteristic according to a bent transducer according to an embodiment of the present invention.
FIG. 7 is a schematic diagram showing the configuration of a conventional bent transducer.
FIG. 8 is a schematic view showing the operation of a conventional bent type transducer.
[Explanation of symbols]
1 Insulating sheath
2 Diaphragm
2a Bending vibration mode
2b Breathing vibration mode
3a, 3b Cylindrical vibrator
4a, 4b Support ring (conventional example)
5 Lead wire
6 bolts
7 Nut
8 Slit
9 Active vibrator
10 Textile material
20 Frequency adjusting material
40a, 40b plate
50 Compound cylindrical vibrator

Claims

A cylindrical elastic body is equally divided into a plurality of parts in the circumferential direction and separated in parallel to each other in the axial direction, and the plurality of diaphragms are equally divided in the axial direction of the cylinder. A plurality of slits, a pair of cylindrical vibrators provided at both axial ends of the plurality of diaphragms arranged in the cylindrical shape, and the cylinders for supplying an electrical signal to the pair of cylindrical vibrators A bending wire generated by bending the plurality of diaphragms in a radial direction of the cylindrical shape, and a pair of cylindrical shapes. A flexural transducer that radiates sound waves into water by resonance with respiratory vibrations generated by the vibrating body and the plurality of diaphragms moving in the radial direction of the cylinder,
The lead is provided between the pair of cylindrical vibrators and the insulating sheath, and is formed by a circular plate having the same outer diameter as the pair of cylindrical vibrators. A pair of plates having a hole through which a wire passes, and a bolt and a nut for fixing the pair of plates so that a distance between the pair of plates is constant, the pair of cylindrical vibrators and the plurality of the plurality of plates In order to expand and contract the pair of plates in the radial direction in accordance with the respiratory vibration of the diaphragm, the pair of plates is made of a unidirectional strength material having relatively high thickness rigidity and relatively low radial rigidity. A flexural transducer characterized by being formed.

With the unidirectional strength material of the pair of plates, the frequency of the sound wave due to the respiratory vibration is brought close to the frequency of the sound wave due to the bending vibration, and the frequency of the sound wave due to the respiratory vibration is superimposed on the frequency of the sound wave due to the bending vibration, 2. The bending transducer according to claim 1, wherein a certain level of transmission / reception level is obtained in a wide frequency band, and a sound wave having a low mechanical resonance frequency can be radiated in a wide frequency band.

The pair of cylindrical vibrators are coaxial with a central axis of a cylindrical array formed by the plurality of diaphragms, and have substantially the same outer periphery as the cylindrical array outer periphery of the plurality of diaphragms, and the plurality of vibrations. The bent transducer according to claim 1 or 2, further comprising an inner circumference having a smaller diameter than an inner circumference of the cylindrical arrangement of the plates.

The pair of cylindrical vibrators have an outer diameter equal to an inner diameter of a cylindrical array of the plurality of diaphragms, and are respectively between an axial center and both ends of the cylindrical array of the plurality of diaphragms. The bent transducer according to claim 1 or 2, characterized in that it is provided.

A bolt penetrates through the center of one of the pair of plates, and the pair of plates are fixed by tightening the bolt with a nut disposed in the center of the other plate. The bent transducer according to any one of claims 1 to 4.

The bending type transducer according to any one of claims 1 to 5, wherein an interface between the pair of plates and the bolts and nuts is filled with an elastic body and is watertightly protected. .

The bent transducer according to claim 6, wherein the elastic body is a synthetic resin.

The pair of cylindrical vibrators includes a plurality of active vibrators arranged in a ring shape in a circumferential direction, a plurality of frequency adjusting members disposed between the plurality of active vibrators, and the plurality of active vibrations. The bending type transmission / reception according to any one of claims 1 to 7, wherein the bending-type transmission / reception is a pair of composite cylindrical vibrators having a body and a fiber material for fastening and fixing the outer periphery of the plurality of frequency adjusting materials. Waver.

9. The bending transducer according to claim 8, wherein each of the plurality of active vibrators is a cylinder or a prism.

The bent transducer according to claim 8 or 9, wherein the frequency of the sound wave due to the respiratory vibration in the radial direction of the pair of composite cylindrical vibrators is adjusted by adjusting the density of the frequency adjusting material. .

The bending type transducer according to claim 10, wherein the frequency due to the respiratory vibration is lowered by increasing the density of the frequency adjusting material so as to be close to the frequency of the sound wave due to the bending vibration.

The bending-type transmission / reception according to claim 11, wherein a transmission level of a certain level or more is obtained in a wide resonance frequency band by superimposing a frequency band of the sound wave due to the respiratory vibration and a frequency band of the sound wave due to the bending vibration. Waver.