JP4181248B2 - Speed measuring device - Google Patents

Description

【００３７】
そして、この共振周波数ｆ１が、上記基準信号の周波数Ｆｏと同じ周波数となるように、上記誘導性インピーダンス素子１３１のインダクタンスＬ１を設定している。この共振周波数では、上記回路のインピーダンスが最も小さくなり、上記超音波振動子を駆動する信号レベルが最も高くなる。
【００３８】
ところが、超音波振動子１１ａの振動部は、圧電セラミックに電極を形成した構造であり、そのキャパシタンスＣｓが、環境条件、例えば温度によって変動してしまう。このため、常温で共振周波数ｆ１が上記基準信号の周波数Ｆｏと等しくなるように設定していても、温度変動によって上記基準信号の周波数Ｆｏから共振周波数ｆ１がずれてしまうことが考えられる。そしてこれにより、上記超音波振動子を駆動する信号レベルが十分に得られず、該超音波振動子１１ａによって送波される音波の送波レベルが小さくなってしまうおそれがある。
【００３９】
図３（ｂ）は、このような環境条件による超音波振動子１１ａのキャパシタンスＣｓの変動に起因する上記送波レベルの低下を防止し得る改良を施した超音波送波部１０の一例を示すものである。この超音波送波部１０においては、上記超音波振動子１１ａと並列にコンデンサ１３３を接続している。該コンデンサ１３３としては、上記超音波振動子１１ａよりも、そのキャパシタンスが温度変動しにくいコンデンサ、例えばフィルムコンデンサを用いることができる。そして、該コンデンサ１３３、上記出力増幅器１３の誘導性インピーダンス素子１３１、及び、上記超音波振動子１１ａを用いて構成される直列共振回路１１１の共振周波数ｆ２が基準信号の周波数Ｆｏと等しくなるように、上記誘導性インピーダンス素子１３１のインダクタンスＬ２を設定している。すなわち、上記コンデンサ１３３のキャパシタンスをＣ１としたときに、次の（４）式を満たすように、該インダクタンスＬ２が設定されている。
【００４０】
【数４】

【００４１】
このように上記コンデンサ１３３を上記超音波振動子１１ａに並列に接続した場合、該超音波振動子１１ａの両端の接点間のキャパシタンス、すなわち図３（ｂ）中の端子Ｎ１と接地端子との間のキャパシタンスは、上記コンデンサ１３３のキャパシタンスＣ１と上記超音波振動子１１ａのキャパシタンスとの和となる。そして、上記（４）式から判るように、上記共振周波数ｆ２は、この和の１／２乗に反比例することとなる。一方、図３（ａ）の直列共振回路の共振周波数ｆ１は、（３）式に示したように、上記超音波振動子１１ａのキャパシタンスの和の１／２乗に反比例する。このため、図３（ｂ）の直列共振回路では、上記コンデンサ１３３を接続しない場合に比して、上記超音波振動子１１ａのキャパシタンスＣｓが直列共振回路の共振周波数に影響を与える割合が小さい。すなわち、該振動子のキャパシタンスＣｓが温度などの環境条件で変動したとしても、この温度変動分が上記共振周波数に影響を与える割合が小さい。しかも、上記コンデンサ１３３のキャパシタンスＣ１は上記超音波振動子１１ａのキャパシタンスよりも変動しにくい。
【００４２】
従って、図３（ｂ）の超音波速度測定装置においては、上記コンデンサＣ１を接続しない場合に比して、共振周波数が所望の周波数すなわち基準信号の周波数Ｆｏからずれにくくなるので、上記超音波振動子に印加する信号レベルが変動しにくくなる。よって、上記超音波振動子１１ａを駆動する信号レベルを十分に得ることができ、該超音波振動子１１ａによって送波される音波の送波レベルが小さくなるのを防止することができる。
【００４３】
この共振周波数のずれを良好に防止するためには、上記コンデンサ１３３のキャパシタンスＣ１を、上記超音波振動子１１ａのキャパシタンスＣｓよりも十分に大きく設定するのが望ましい。具体的には、上記コンデンサ１３３のキャパシタンスＣ１を、上記超音波振動子１１ａのキャパシタンスＣｓの５倍〜５０倍、好ましくは、１０倍〜１５倍に設定すればよい。このように設定すれば、上記共振周波数ｆ２は、上記コンデンサのキャパシタンスＣ１と上記誘導性インピーダンス素子１３２のインダクタンスとによってほぼ決定されることとなる。本発明者らが、常温でのキャパシタンスＣｓが２４００ｐＦの超音波振動子１１ａ及び２２０００ｐＦのコンデンサ１３３を用いたところ、十分な送波レベルを安定して送波することができた。
【００４４】
図３（ａ）及び（ｂ）の超音波送波部１０は、基準信号を送波器の駆動に必要なレベルまで増幅するために、上記直列共振回路１１０、１１１とは別個に設けた増幅器１３ａを有しているが、該直列共振回路１１０、１１１を、上記基準信号を送波器１１の駆動に必要なレベルに増幅して該送波器１１の超音波振動子１１ａに印加するように構成してもよい。具体的には、直列共振回路１１０において、上記共振周波数ｆ２の信号は「共振回路のＱ」倍に増幅されて上記超音波振動子１１ａに印加されることとなるので、該共振回路のＱが、上記基準信号を送波器の駆動に必要なレベルまで増幅できるような値となるように、上記直列共振回路の誘導性インピーダンス素子１３１の抵抗値を設定すればよい。このように上記直列共振回路１１０を構成すれば、上記増幅器１３ａを別個に設ける必要がなくなり、装置構成を簡単にできる点で好ましい。また、このように直列共振回路１１０を構成し、かつ、上記増幅器１３ａを設けた場合には、上記基準発振器１２からの信号レベルを低減させても、十分に送波レベルを確保することが可能となる。よって、低電圧動作が実現可能となる。なお、直列共振回路で共振周波数での信号を前記「共振回路のＱ」倍に増幅するためには、該共振回路前段の回路の出力インピーダンスが十分に低いことが必要であるので、前記増幅器１３ａを設ける場合には、該増幅器１３ａとして、出力インピーダンスが十分に低いものを用いるのが良い。また、前記増幅器１３ａを設けない場合には、前記共振回路前段に、出力インピーダンスが十分に低いバッファ回路を設ければよい。
【００４５】
図４は、上記超音波送波部１０の他の一例を示す説明図である。この超音波送波部１０は、上記基準発信器からの出力信号を昇圧する昇圧用のトランス１４を有している。具体的には、該昇圧用のトランス１４の１次側のコイルに上記出力信号が入力され、２次側のコイルが上記超音波振動子１１ａに接続されている。該トランスの１次側のコイルと２次側のコイルとの巻線数の比は１：ｎとなっている。また、この超音波送波部１０においても、図３（ｂ）の超音波送波部１０の場合と同様、超音波振動子１１ａのキャパシタンスＣｓの温度変動による送波レベルの低下を防止するために、超音波振動子１１ａに並列にコンデンサ１３４が接続されている。そして、上記トランスを２次側から見て、１つのコイルに等価変換したときの該コイルのインダクタンス（以下、トランスのインダクタンスという）Ｌ２と、上記コンデンサ１３４と、上記超音波振動子１１ａのキャパシタンスＣｓとで構成される直列共振回路の共振周波数ｆ３が、上記基準信号の周波数Ｆｏと等しくなるように、上記トランスのインダクタンスＬ２が設定されている。具体的には、上記コンデンサ１３４のキャパシタンスをＣ２としたときに、次の（５）式を満たすように、上記トランスのインダクタンスＬ２が設定されている。
【００４６】
【数５】

【００４７】
これにより、図３（ｂ）の超音波送波部１１と同様に、上記超音波振動子１１ａを駆動する信号レベルを十分に得ることができ、該超音波振動子１１ａによって送波される音波の送波レベルが小さくなるのを防止することができる。
【００４８】
しかも、図４の超音波送波部１１においては、上記昇圧用のトランス１４で、上記基準信号の信号レベルをｎ倍に増幅することができるので、簡素な構成で該基準信号を送波器１１の駆動に必要なレベルに増幅することができる。
さらに、この超音波送波部１１で、共振回路のＱが、上記基準信号を送波器の駆動に必要なレベルまで増幅できるような値となるように、上記直列共振回路を構成すれば、上記基準発振器１２からの信号レベルを低減させても、十分に送波レベルを確保することが可能となる。よって、さらに低電圧動作が実現可能となる。
【００４９】
以上、本実施形態に係る速度測定装置によれば、ノッチフィルタ２５よりも後段にある前置増幅器２２やミキサ２３が飽和レベルに到達しないという条件下で前置増幅器２２の増幅度や送波器１１の送波レベルの上限を高くすることができるので、送波器１１から受波器２１への直接波の回り込みや、ボール５０の近辺にある静止物体からの超音波の反射があっても、小さく且つ本装置から遠くにある対象物であるボール５０の速度を精度良く測定することができる。
【００５０】
また、本実施形態に係る速度測定装置において、上記超音波送波部１０として、キャパシタンス成分を有する超音波振動子１１ａと、上記基準信号と同じ周波数Ｆｏの信号を選択的に該超音波振動子１１ａに印加して該超音波振動子１１ａを駆動すべく、共振周波数が上記基準信号と同じ周波数Ｆｏに設定された直列共振回路を、上記超音波振動子１１ａと共に構成する誘導性インピーダンス素子とを有し、かつ、上記超音波振動子１１ａを駆動することで上記超音波を送波するものを用いた場合には、図３（ｂ）、あるいは、図４の例のように、上記超音波振動子１１ａと並列に、該超音波振動子に比して、キャパシタンスが環境条件によって変動しにくいコンデンサを接続し、かつ、上記誘導性インピーダンス素子、コンデンサ、及び、超音波振動子１１ａを用いて構成される上記直列共振回路の共振周波数が基準信号の周波数Ｆｏと等しくなるように上記誘導性インピーダンス素子のインダクタンスを設定するのが望ましい。このような構成を採用すれば、上記超音波振動子１１ａを駆動する信号レベルを十分に得ることができ、該超音波振動子１１ａによって送波される音波の送波レベルが小さくなるのを防止することができる。
【００５１】
〔実施形態２〕
図５は、本発明の他の実施形態に係る速度測定装置のブロック図である。なお、本速度測定装置の超音波送波部１０、超音波受波部２０の受波器２１からミキサ２３までの部分、及び信号処理部３０の構成は、前述の図１の構成と同様であるので、それらの説明は省略する。なお、本装置の信号処理部３０には、気温による音速変動の補正に用いる温度計測器３４を設けている。
【００５２】
前述の図１の装置において受波器２１に入ってくる反射波は一つの周波数成分とは限らない場合がある。すなわち、反射波を発生させる対象物が車や空中を飛んでくるボールのように一つだけであれば、それらの対象物から反射されてくるドップラシフトを受けた反射波の周波数は一つであると考えることができ、抽出されるドップラ信号成分は正弦波となる。しかしながら、例えばピッチャーが投げるボールの初速を測定するような場合では、図６（ａ）に示すようにボール以外にピッチャーの腕や身体のあらゆる部分から周波数の異なるドップラシフトを受けた反射波信号成分Ｆi1〜Ｆi5を含む音波が反射されてくる。このように周波数の異なる複数の反射波信号成分Ｆi1〜Ｆi5を含む音波を受信すると、図６（ｂ）に示すように受信信号Ｆｉの波形は歪みを生じ、周波数の誤計測を招く可能性がある。
【００５３】
そこで、本実施形態では、上記複数の反射波信号成分に対応する差分信号成分Ｆd1〜Ｆd5のすべてを通過させてしまうローパスフィルタ２４に代えて、差分信号成分がとり得る周波数帯域を複数に分割した部分帯域のそれぞれに通過帯域が設定された複数の部分帯域通過部を有し、且つ該複数の部分帯域通過部を通過する複数の差分信号成分の中から選択して出力するように構成した分割帯域通過手段を設けている。
【００５４】
上記分割帯域通過手段は、上記部分帯域通過部として５個のバンドパスフィルタＢＰＦを含むフィルタ群２６と、各ＢＰＦを通過した信号を検出する５個の信号検出器を含む検出器群２７と、各信号検出器から出力される信号の中から一つの信号を速度Ｖを演算するための差分信号成分として選択する信号選択器２８とを用いて構成されている。
【００５５】
上記バンドパスフィルタ群２６は、高周波側から５つの通過帯域（ＨＨ，ＨＬ，Ｍ，ＬＨ，ＬＬ）に分割構成され、ミキサ２３から入力された差分信号成分を各帯域信号Ｓｅ（ＳｅＨＨ〜ＳｅＬＬ）に分離して信号検出器群２７に及び信号選択器２８に出力する。ここで、上記基準信号の周波数Ｆｏを３２．７６８ｋＨｚとし、測定速度範囲を１０〜２００ｋｍ／ｈとすると、ドップラ信号成分としての差分信号成分の周波数Ｆｄは上記（１）式により５３０Ｈｚ〜１２．５ｋＨｚとなるので、例えば上記５個のＢＰＦ１〜ＢＰＦ５の中心周波数をそれぞれ１．５ｋＨｚ、３．５ｋＨｚ、５．５ｋＨｚ、９．５ｋＨｚ、１１．５ｋＨｚに設定し、通過帯域幅を２ｋＨｚに設定すればよい（図６（ｃ）参照）。なお、上記バンドパスフィルタＢＰＦおよび信号検出器の個数は、５個に限定されるものではなく、測定速度範囲と要求される測定精度に応じて決定される。
【００５６】
上記信号検出器群２７は、バンドパスフィルタ群２６から出力される各帯域信号Ｓｅのうち、各信号検出器に予め設定されている閾値よりも大きな信号レベルをもつ帯域信号を優位レベルの検出信号Ｓｆとして信号選択器２８に出力する。
【００５７】
上記信号選択器２８は、優位レベルをもつ検出信号Ｓｆから最も周波数の高い検出信号Ｓｈを選択して、周波数計測器３１に出力する。ここで、複数の検出信号Ｓｆから最も周波数の高い信号を選択する理由は、例えばピッチャーから反射された超音波とボール５０から反射された超音波との周波数を比べた場合、ボールから反射された超音波の周波数が高い（ドップラ周波数が高い）ためである。なお、対象物から反射された超音波と目的外の超音波との関係が上述した関係にない場合には、信号選択器２８で選択する基準を適宜設ければよい。
【００５８】
上記信号選択器２８でどのバンドパスフィルタＢＰＦを通過した信号を選択するかについては、いくつかの方法が考えられる。例えば、本実施形態のように信号検出器から同時に複数の信号が出力される場合は中心周波数が一番高いＢＰＦを通過した信号を選択する方法や、一番最初に信号検出器から出力された信号を選択する方法などがある。
【００５９】
図７は、本実施形態に係る速度測定装置の他の一例のブロック図である。この速度測定装置においては、上記分割帯域通過手段を、アナログ信号をデジタル信号に変換するアナログ／デジタル変換器とディジタル信号処理手段とを用いて構成している。具体的には、図５の速度測定装置におけるフィルタ群２６、検出器群２７、信号選択器２８、周波数計測器３１、及び、演算器３２に代え、アナログ／デジタル変換器（以下、ＡＤ変換器という）６１及び前記フィルタ群２６、検出器群２７、信号選択器２８、周波数計測器３１、及び、演算器３２の機能を有し、ディジタル信号を処理するディジタル信号処理手段としてのＤＳＰ６２を設けている。該ディジタル信号処理手段としては、ＤＳＰ６２以外の１チップ化したディジタル信号処理用のＩＣ、例えばマイコンなどを用いてもよい。
【００６０】
上記ＡＤ変換器６１では、ミキサ２３から出力されたアナログ信号を、デジタル信号に変換する。そして、上記ＤＳＰ６２においては、例えばフーリエ変換などのディジタルフィルタ処理を行うことで、前記フィルタ群と同様の作用を得ることができる。
【００６１】
そして前記フィルタ処理を行った後に、信号検出処理、信号選択処理を行って得られるディジタル信号に対して周波数を求めて、前記ボール５０の移動速度Ｖを演算する。
【００６２】
なお、上記ディジタル信号処理手段としてのＤＳＰ６２に持たせる機能は、前記フィルタ群２６、検出器群２７、信号選択器２８、周波数計測器３１、及び、演算器３２の機能に限定されるものではなく、該ディジタル信号処理手段の処理能力に合わせて、その範囲を適宜選択すればよい。
【００６３】
以上、本実施形態に係る速度測定装置によれば、図１の装置と同様に、送波器１１から受波器２１への直接波の回り込みや、ボール５０の近辺にある静止物体からの超音波の反射があっても、小さく且つ本装置から遠くにある対象物であるボール５０の速度を精度良く測定することができる。しかも、ドップラ信号成分としてのほぼ正弦波となった差分信号成分に基づいて、ボール５０の速度を演算することができるので、ボール５０からの反射波以外の異なる周波数の複数の超音波が同時に受波されたときの誤計測の発生を抑えることができる。
【００６４】
〔実施形態３〕
図８は、本発明のさらに他の実施形態に係る速度測定装置のブロック図である。本速度測定装置の超音波送波部１０、超音波受波部２０の一部及び信号処理部３０の構成は、前述の図５の構成と同様であるので、それらの説明は省略する。
【００６５】
本実施形態では、図５の装置で用いたミキサ２３を設けずに、前置増幅器２２の後段に設けたノッチフィルタ２５を、上記バンドパスフィルタ群２６に入力する受信信号中の反射波信号成分を通過させるように構成している。ノッチフィルタ２５の基本波信号成分に対する減衰率は、後段のバンドパスフィルタ群２６における飽和特性や周波数計測器３１における周波数計測能力等を考慮し、それらの回路における信号処理に影響を及ぼさない大きさに設定する。例えば、前置増幅器２２の出力側で反射波信号成分と基本波信号成分のレベル比がほぼ１対１であり、周波数計測器３１の計測に必要な反射波信号成分と雑音成分（基本波信号成分を含む）のレベル比が４対１である場合、ノッチフィルタ２５の基本波信号成分に対する減衰率を１／４すなわち−１２ｄＢに設定する。なお、前置増幅器２２における信号の飽和も問題になる場合には、受波器２１と前置増幅器２２との間にノッチフィルタを設けたり、前置増幅器２２の前段と後段の両方にノッチフィルタを設けたりしてもよい。
【００６６】
また、図５のミキサ２３を用いた装置の場合、バンドパスフィルタ群２６の通過帯域はビートダウンした５３０Ｈｚ〜１２．５ｋＨｚであったが、本実施形態の図８の装置の場合は、ビートダウン前の反射波信号成分がとり得る周波数帯域３３．３ｋＨｚ〜４５．７ｋＨｚを複数に分割してバンドパスフィルタ群２６を構成すればよい。
【００６７】
なお、図８の速度測定装置においては、差分信号成分の周波数ではなく、上記反射波信号成分の周波数を用いて速度を演算するような構成を採用している。具体的には、信号処理部３０を、前出の（１）式にＦｄ＝Ｆｉ−Ｆｏを代入して得られる式に基づいてボール５０の移動速度Ｖを演算するように構成すればよい。
【００６８】
本実施形態に係る速度測定装置においても、図７の速度測定装置と同様に、上記分割帯域通過手段としてのバンドパスフィルタ群２６を、アナログ信号をデジタル信号に変換するアナログ／デジタル変換器とディジタル信号処理手段とを用いて構成してもよい。図９は、このような構成を採用した速度測定装置の一例を示すブロック図である。図９の装置においては、図８の速度測定装置におけるフィルタ群２６、検出器群２７、信号選択器２８、周波数計測器３１、及び、演算器３２に代え、アナログ／デジタル変換器（以下、ＡＤ変換器という）６１及び前記フィルタ群２６、検出器群２７、信号選択器２８、周波数計測器３１、及び、演算器３２の機能を有し、ディジタル信号を処理するディジタル信号処理手段としてのＤＳＰ６２を設けている。該ディジタル信号処理手段としては、ＤＳＰ６２以外の１チップ化したディジタル信号処理用のＩＣ、例えばマイコンなどを用いてもよい。
【００６９】
上記ＡＤ変換器６１では、ノッチフィルタ２５から出力されたアナログ信号を、デジタル信号に変換する。そして、上記ＤＳＰ６２においては、例えばフーリエ変換などのディジタルフィルタ処理を行うことで、前記フィルタ群と同様の作用を得ることができる。
【００７０】
そして前記フィルタ処理を行った後に、信号検出処理、信号選択処理を行って得られるディジタル信号に対して周波数を求めて、前記ボール５０の移動速度Ｖを演算する。
【００７１】
なお、本実施形態においても、上記ディジタル信号処理手段としてのＤＳＰ６２に持たせる機能は、前記フィルタ群２６、検出器群２７、信号選択器２８、周波数計測器３１、及び、演算器３２の機能に限定されるものではなく、該ディジタル信号処理手段の処理能力に合わせて、その範囲を適宜選択すればよい。
【００７２】
以上、本実施形態に係る速度測定装置によれば、ミキサを設けることなく、送波器１１から受波器２１への直接波の回り込みや、ボール５０の近辺にある静止物体からの超音波の反射があっても、小さく且つ本装置から遠くにある対象物であるボール５０の速度を精度良く測定することができるとともに、ボール５０からの反射波以外の異なる周波数の複数の超音波が同時に受波されたときの誤計測の発生を抑えることができる。しかも、ミキサ２３から出力される反射波信号成分と基準信号との差分をドップラ信号成分として用いる場合とは異なり、ドップラ信号成分として用いた上記反射波信号成分の周波数の値に基づいてボール５０が近づいているか若しくは遠ざかっているかを区別してボール５０の速度を測定できる。
【００７３】
〔実施形態４〕
図１０は、本発明のさらに他の実施形態に係る速度測定装置のブロック図である。本速度測定装置の超音波送波部１０、超音波受波部２０の一部及び信号処理部３０の構成は、前述の図５の構成と同様であるので、それらの説明は省略する。
（以下、余白）
【００７４】
本実施形態では、図５の装置で用いたミキサ２３及びノッチフィルタ２５を設けずに、バンドパスフィルター群２６の各ＢＰＦ自体に、周波数ｆｏの基本波信号成分を減衰させるノッチフィルタの機能を持たせている。すなわち、各ＢＰＦの選択度（Ｑ）を、基本波信号成分を必要なレベルまで減衰するように高めている。各ＢＰＦの基本波信号成分に対する減衰率は、後段の周波数計測器３１における周波数計測能力等を考慮し、周波数計測に影響を及ぼさない大きさに設定する。例えば、前置増幅器２２の出力側で反射波信号成分と基本波信号成分のレベル比がほぼ１対１であり、周波数計測器３１の計測に必要な反射波信号成分と雑音成分（基本波信号成分を含む）のレベル比が４対１である場合、各ＢＰＦの基本波信号成分に対する減衰率を１／４すなわち−１２ｄＢに設定する。
【００７５】
なお、本実施形態の構成の場合、前置増幅器２２のゲインはバンドパスフィルタ群２６で信号が飽和しない程度に抑えるのが好ましい。ゲインの不足分はバンドパスフィルタ群２６の各ＢＰＦに必要なだけゲインを持たせればよい。
【００７６】
また、図１０の速度測定装置においても、図８の速度測定装置と同様、差分信号成分の周波数ではなく、上記反射波信号成分の周波数を用いて速度を演算するような構成を採用している。具体的には、信号処理部３０を、前出の（１）式にＦｄ＝Ｆｉ−Ｆｏを代入して得られる式に基づいてボール５０の移動速度Ｖを演算するように構成すればよい。
【００７７】
本実施形態に係る速度測定装置においても、図７の速度測定装置と同様に、上記分割帯域通過手段としてのバンドパスフィルタ群２６を、アナログ信号をデジタル信号に変換するアナログ／デジタル変換器とディジタル信号処理手段とを用いて構成してもよい。図１１は、このような構成を採用した速度測定装置の一例を示すブロック図である。図１１の装置においては、図１０の速度測定装置におけるフィルタ群２６、検出器群２７、信号選択器２８、周波数計測器３１、及び、演算器３２に代え、アナログ／デジタル変換器（以下、ＡＤ変換器という）６１及び前記フィルタ群２６、検出器群２７、信号選択器２８、周波数計測器３１、及び、演算器３２の機能を有し、ディジタル信号を処理するディジタル信号処理手段としてのＤＳＰ６２を設けている。該ディジタル信号処理手段としては、ＤＳＰ６２以外の１チップ化したディジタル信号処理用のＩＣ、例えばマイコンなどを用いてもよい。
【００７８】
上記ＡＤ変換器６１では、前置増幅器２２から出力されたアナログ信号を、デジタル信号に変換する。そして、上記ＤＳＰ６２においては、例えばフーリエ変換などのディジタルフィルタ処理を行うことで、前記フィルタ群と同様の作用を得ることができる。
【００７９】
そして前記フィルタ処理を行った後に、信号検出処理、信号選択処理を行って得られるディジタル信号に対して周波数を求めて、前記ボール５０の移動速度Ｖを演算する。
【００８０】
なお、本実施形態においても、上記ディジタル信号処理手段としてのＤＳＰ６２に持たせる機能は、前記フィルタ群２６、検出器群２７、信号選択器２８、周波数計測器３１、及び、演算器３２の機能に限定されるものではなく、該ディジタル信号処理手段の処理能力に合わせて、その範囲を適宜選択すればよい。
【００８１】
以上、本実施形態に係る速度測定装置によれば、ミキサを設けたりノッチフィルタを独立に設けたりすることなく、図８の装置と同様に、送波器１１から受波器２１への直接波の回り込みや、ボール５０の近辺にある静止物体からの超音波の反射があっても、小さく且つ本装置から遠くにある対象物であるボール５０の速度を精度良く測定することができるとともに、ボール５０からの反射波以外の異なる周波数の複数の超音波が同時に受波されたときの誤計測の発生を抑えることができる。しかも、ミキサ２３から出力した反射波信号成分と基準信号との差分をドップラ信号成分として用いる場合とは異なり、ドップラ信号成分として用いた上記反射波信号成分の周波数の値に基づいてボール５０が近づいているか若しくは遠ざかっているかを区別してボール５０の速度を測定できる。
【００８２】
なお、上記実施形態２乃至４のそれぞれに係る速度測定装置においても、超音波送波部１０として、図３（ａ）、（ｂ）、及び、図４に示したものを用いることができる。そして、実施形態２乃至４のそれぞれに係る速度測定装置においても、上記超音波送波部１０として、キャパシタンス成分を有する超音波振動子１１ａと、上記基準信号と同じ周波数Ｆｏの信号を選択的に該超音波振動子１１ａに印加して該超音波振動子１１ａを駆動すべく、共振周波数が上記基準信号と同じ周波数Ｆｏに設定された直列共振回路を、上記超音波振動子１１ａと共に構成する誘導性インピーダンス素子とを有し、かつ、上記超音波振動子１１ａを駆動することで上記超音波を送波するものを用いた場合には、図３（ｂ）、あるいは、図４の例のように、上記超音波振動子１１ａと並列に、該超音波振動子に比して、キャパシタンスが環境条件によって変動しにくいコンデンサを接続し、かつ、上記誘導性インピーダンス素子、コンデンサ、及び、超音波振動子１１ａを用いて構成される上記直列共振回路の共振周波数が基準信号の周波数Ｆｏと等しくなるように上記誘導性インピーダンス素子のインダクタンスを設定するのが望ましい。このような構成を採用すれば、上記超音波振動子１１ａを駆動する信号レベルを十分に得ることができ、該超音波振動子１１ａによって送波される音波の送波レベルが小さくなるのを防止することができる。
【００８３】
また、上記実施形態１乃至４の各実施形態では、音波を送波する対象物がボールであり、該ボールの速度を測定するものについて説明したが、該対象物はボールに限定されるものではない。本発明は、道路等の静止した対象物上を移動する自動車などの移動物体側に、本装置を備え、該対象物の相対移動速度すなわち本装置を備えた移動物体の移動速度を測定するような速度測定装置にも適用できるものである。
【００８４】
また、送波手段及び信号処理手段の構成は、上記各実施形態の超音波送波部１０及び信号処理部３０の構成に限定されるものでなく、本発明は、他の構成の送波手段及び信号処理手段を採用した場合にも適用できるものである。
【００８５】
【発明の効果】
請求項１乃至５の発明によれば、受波手段内の信号減衰手段よりも後段にある信号処理回路の信号レベルが飽和レベルに到達しないという条件下で受信信号の増幅度や送波手段の送波レベルの上限を高くすることができるので、送波手段から受波手段への音波の回り込みや、対象物の近辺にある静止物体からの音波の反射があっても、小さい対象物や遠くにある対象物の相対速度を精度良く測定することができる。
【００８６】
特に、請求項１の発明によれば、信号減衰手段よりも後段にある増幅器や混合器等の信号処理回路の信号レベルが飽和レベルに到達しないという条件下で受信信号の増幅度や送波手段の送波レベルの上限を高くすることができる。
【００８７】
特に、請求項２の発明によれば、信号減衰手段よりも後段にある混合器等の信号処理回路の信号レベルが飽和レベルに到達しないという条件下で受信信号の増幅度や送波手段の送波レベルの上限を高くすることができる。
【００８８】
特に、請求項１叉は２の発明によれば、ドップラ信号成分としてのほぼ正弦波となった差分信号成分に基づいて、本装置に対する対象物の相対移動速度を演算することができるので、対象物からの反射波以外に異なる周波数の複数の音波が同時に受波されたときの誤計測の発生を抑えることができる。
【００８９】
特に、請求項３の発明によれば、基準信号と受信信号とを混合する混合器を設けることなく、受波手段内の信号処理回路の信号レベルが飽和レベルに到達しないという条件下で受信信号の増幅度や送波手段の送波レベルの上限を高くすることができるとともに、異なる周波数のドップラシフトを受けた反射波信号成分が同時に受波されたときの誤計測の発生を抑えることができる。しかも、反射波信号成分と基準信号との差分をドップラ信号成分として用いる場合とは異なり、ドップラ信号成分として用いた上記反射波信号成分の周波数の値に基づいて本装置と対象物とが近づいているか若しくは遠ざかっているかを区別して測定できる。
【００９０】
特に、請求項４の発明によれば、上記基準信号と同じ周波数の信号成分のみを確実に減衰させることができる。
【００９１】
特に、請求項５の発明によれば、信号減衰手段を独立に設けることなく、受波手段内の信号処理回路の信号レベルが飽和レベルに到達しないという条件下で受信信号の増幅度や送波手段の送波レベルの上限を高くすることができるとともに、異なる周波数のドップラシフトを受けた反射波信号成分が同時に受波されたときの誤計測の発生を抑えることができる。しかも、反射波信号成分と基準信号との差分をドップラ信号成分として用いる場合とは異なり、ドップラ信号成分として用いた上記反射波信号成分の周波数の値に基づいて本装置と対象物とが近づいているか若しくは遠ざかっているかを区別して測定できる。
【図面の簡単な説明】
【図１】本発明の一実施形態に係る速度測定装置のブロック図。
【図２】上記構成の速度測定装置の超音波受波部２０中の複数箇所（Ａ〜Ｄ点）における各周波数（Ｆｏ，Ｆｉ，Ｆｄ）の信号成分の振幅（レベル）を示す説明図。
【図３】（ａ）及び（ｂ）は、同速度測定装置の超音波送波部１０の構成例を示す図。
【図４】同超音波送波部１０の他の構成例を示す図。
【図５】他の実施形態に係る速度測定装置のブロック図。
【図６】（ａ）は周波数の異なる複数の反射波信号成分Ｆｉ１〜Ｆｉ５の波形の説明図。
（ｂ）は同反射波信号成分Ｆｉ１〜Ｆｉ５を合成した信号の波形の説明図。
（ｃ）はバンドパスフィルタ群のフィルタ特性及び入力信号（Ｆｏ，Ｆｉ，Ｆｄ）の説明図。
【図７】同速度測定装置の他の一例を示すブロック図。
【図８】更に他の実施形態に係る速度測定装置のブロック図。
【図９】同速度測定装置の他の一例を示すブロック図。
【図１０】更に他の実施形態に係る速度測定装置のブロック図。
【図１１】同速度測定装置の他の一例を示すブロック図。
【図１２】従来例に係る速度測定装置のブロック図。
【図１３】同速度測定装置における前置増幅器及びミキサのダイナミックレンジの説明図。
【符号の説明】
１０ 超音波送波部
１１ 送波器
１１ａ 超音波振動子
２０ 超音波受波部
２１ 受波器
２２ 前置増幅器
２３ ミキサ
２４ ローパスフィルタ
２５ ノッチフィルタ
２６ バンドパスフィルタ群
２７ 信号検出器群
２８ 信号選択器
３０ 信号処理部
３１ 周波数計測器
３２ 演算器
３３ 表示器
５０ ボール
１３１、１３２ 誘導性インピーダンス素子
１３３ コンデンサ
１３４ コンデンサ
１４ トランス[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a speed measurement device that measures the relative movement speed of an object relative to the apparatus based on the frequency of a Doppler signal component of a received signal obtained by receiving a sound wave reflected from the object. .
[0002]
[Prior art]
Conventionally, as this type of velocity measuring device, a transmitting means for transmitting a sound wave generated based on a reference signal of a predetermined frequency toward an object, and a received signal by receiving the sound wave reflected from the object And a speed measuring device comprising: wave receiving means for extracting a Doppler signal component in the received signal; and speed calculating means for calculating a relative moving speed of the object with respect to the apparatus based on the Doppler signal component. It has been.
[0003]
[Problems to be solved by the invention]
In the conventional speed measuring device, in order to obtain a predetermined measurement accuracy even when the object to which the sound wave is transmitted is small or the object is far away, Measures such as raising the level or increasing the amplification of the signal in the wave receiving means were necessary. However, if these measures are taken, a sound wave having a level higher than that of the reflected wave from the object and having the same frequency as that of the reference signal may circulate from the transmitting means to the receiving means, or be located in the vicinity of the object. When the receiving means receives a reflected wave that does not receive the Doppler effect reflected from a stationary object, the possibility that the signal processing circuit such as the amplifier or mixer of the receiving means is saturated increases, and normal signal processing is performed. There was a risk that it would be impossible.
[0004]
FIG. 12 is a block diagram showing a configuration example of a conventional speed measuring device, and FIG. 13 is an explanatory diagram of a dynamic range that is an allowable input range of a preamplifier and a mixer (mixer) in the speed measuring device. This velocity measuring device includes an ultrasonic wave transmission unit 10 as a wave transmission unit having the wave transmitter 11, an ultrasonic wave reception unit 20 as a wave reception unit having a wave receiver 21, and a signal processing unit 30. I have. In addition to the receiver 21, the ultrasonic receiver 20 includes a preamplifier 22 and a mixer 23. Here, as shown in FIG. 13, when the voltage amplification degree (gain) Gamp of the preamplifier 22 is 200 times, the noise level of the mixer 23 is 2 mV, and the saturation levels of the preamplifier 22 and the mixer 23 are 1 V, the mixer 23 The dynamic range DRmix is 2 mV to 1 V, and the relative dynamic range DRamp of the preamplifier 22 viewed from the mixer 23 side is 10 μV to 5 mV. Therefore, the lower limit of the input level of the preamplifier capable of processing the ultrasonic wave reflected from the relative moving object and subjected to the Doppler shift is 10 μV, and the ultrasonic wave that has passed from the transmitter 11 to the receiver 21. And the allowable input level of the preamplifier 22 corresponding to the reflected ultrasonic waves from the stationary object is less than 5 mV. In such a speed measurement device, if the gain Gamp of the preamplifier 22 is increased to 400 times, for example, the allowable input level of the preamplifier 22 is reduced to less than 2.5 mV. Some consideration is required, such as reducing the level of the ultrasonic wave to be halved or reducing the direct wave wraparound from the transmitter 11 to the receiver 21. Therefore, it becomes difficult to accurately measure the relative speed of a small object or a far object.
[0005]
The present invention has been made in view of the above problems, and its purpose is that even if there is a wraparound of sound waves from the transmitting means to the receiving means or reflection of sound waves from a stationary object in the vicinity of the object, It is an object of the present invention to provide a speed measuring device capable of accurately measuring the relative speed of a small object or a far object.
[0006]
[Means for Solving the Problems]
  In order to achieve the above object, claims 1 to5The invention includes a wave transmitting means for transmitting a sound wave generated based on a reference signal having a predetermined frequency toward an object, and a sound wave reflected from the object is received as a received signal. A throwing ball speed measuring device comprising: a wave receiving means for extracting a Doppler signal component of the pitch; and a speed calculating means for calculating a relative moving speed of the object relative to the apparatus based on the Doppler signal component. The means is provided with a signal attenuating means for selectively attenuating a signal component having the same frequency as the reference signal.
[0007]
  ThereforeThe signal component having the same frequency as the reference signal among the received signals that have received the sound waves reflected from the object by the signal attenuating means provided in the receiving means, that is, the wraparound of the sound waves from the transmitting means to the receiving means The signal component corresponding to the reflection of the sound wave from the stationary object in the vicinity of the object is selectively attenuated. As a result of this selective signal attenuation, the amplification level of the received signal and the transmission of the transmission means under the condition that the signal level of the signal processing circuit in the subsequent stage of the signal attenuation means in the reception means does not reach the saturation level. The upper limit of the level can be increased.
[0008]
  AndClaim1According to the present invention, the receiving means includes a receiver that receives the sound wave reflected from the object, an amplifier that amplifies a reception signal output from the receiver, and a reception that is output from the amplifier. A mixer for mixing a signal and the reference signal, and a band for selectively passing the difference between the reflected wave signal component subjected to Doppler shift from the signal output from the mixer and the reference signal as the Doppler signal component And using passing means,The signal attenuation means is provided between the receiver and the amplifier.It was.
[0009]
  Therefore,A signal processing circuit such as an amplifier or a mixer located downstream of the signal attenuating means by selective attenuation of the specific signal component performed by a signal attenuating means provided between the receiver and the amplifier of the receiving means. Under the condition that the signal level does not reach the saturation level, the upper limit of the amplification degree of the received signal and the transmission level of the transmission means can be increased.
[0010]
  Also,Claim2According to the present invention, the receiving means includes a receiver that receives the sound wave reflected from the object, an amplifier that amplifies a reception signal output from the receiver, and a reception that is output from the amplifier. A mixer for mixing a signal and the reference signal, and a band for selectively passing the difference between the reflected wave signal component subjected to Doppler shift from the signal output from the mixer and the reference signal as the Doppler signal component Configuration using passing meansAndThe signal attenuating means is provided between the amplifier and the mixer.It was.
[0011]
  ThereforeThe signal of the signal processing circuit such as a mixer in the subsequent stage of the signal attenuation means by selective attenuation of the specific signal component performed by the signal attenuation means provided between the amplifier of the receiving means and the mixer Under the condition that the level does not reach the saturation level, the upper limit of the amplification degree of the received signal and the transmission level of the transmission means can be increased.
[0012]
  AndClaim1 and 2The invention of,UpThe band passing means has a plurality of partial band passing sections each having a pass band set in each of the partial bands obtained by dividing the frequency band that can be taken by the differential signal component, and passes through the plurality of partial band passing sections. This is characterized in that it is configured to select and output from a plurality of differential signal components.
[0013]
  ThereforeThe signal output from the mixer is input to the band pass means at the subsequent stage, selected from the plurality of received signals passing through the plurality of partial band pass sections, and output, so that the Doppler is substantially a sine wave. Based on the differential signal component as the signal component, the relative movement speed of the object with respect to the present apparatus can be calculated.
Moreover, the above selection is made to select the one with the highest frequency.
Therefore, the ultrasonic wave reflected from the ball can be selected instead of the ultrasonic wave reflected from the pitcher. This is because when the frequency of the ultrasonic wave reflected from the pitcher and the ultrasonic wave reflected from the ball are compared, the frequency of the ultrasonic wave reflected from the ball is high (the Doppler frequency is high).
[0014]
  Also,Claim3The invention of,UpThe wave receiving means has a plurality of partial band passing portions each having a pass band set in each of the partial bands obtained by dividing the frequency band that can be taken by the reflected wave signal component subjected to the Doppler shift of the received signal. A divided band passing means configured to select and output from a plurality of received signals passing through the plurality of partial band passing sections is provided, and the signal attenuating means is included in the received signal input to the divided band passing means. Configured to pass the reflected wave signal component ofIt was.
[0015]
  ThereforeThe received signal under the condition that the signal level of the signal processing circuit such as the divided band passing means subsequent to the signal attenuation means does not reach the saturation level due to the selective attenuation of the specific signal component performed by the signal attenuation means. The upper limit of the degree of amplification and the transmission level of the transmission means can be increased. Then, the signal attenuation means selectively attenuates the specific signal component and receives a reception signal including the reflected wave signal component subjected to Doppler shift to the divided band passing means, and passes through a plurality of partial band passing portions. By selecting and outputting from a plurality of received signals, it is possible to calculate the relative movement speed of the object with respect to the present apparatus based on the reflected wave signal component as a Doppler signal component that is substantially a sine wave. .
Moreover, the above selection is made to select the one with the highest frequency.
Therefore, the ultrasonic wave reflected from the ball can be selected instead of the ultrasonic wave reflected from the pitcher. This is because when the frequency of the ultrasonic wave reflected from the pitcher and the ultrasonic wave reflected from the ball are compared, the frequency of the ultrasonic wave reflected from the ball is high (the Doppler frequency is high).
[0016]
  Claim4The invention of claim 1 and 2Fork 3ofOf throwing ballIn the speed measurement device, a band-stop filter in which the center frequency of the attenuation band is set to the frequency of the reference signal is used as the signal attenuation means.It was.
[0017]
  ThereforeBy using a band rejection filter in which the center frequency of the attenuation band is set as the frequency of the reference signal as the signal attenuating means, it is possible to reliably attenuate only the specific signal component.
  A notch filter is preferably used as the band rejection filter. This notch filter has a high Q in the attenuation band, and has an excellent function of attenuating only the specific signal component.
[0018]
  Also,Claim5The invention of,UpThe wave receiving means has a plurality of partial band passing portions each having a pass band set in each of the partial bands obtained by dividing the frequency band that can be taken by the reflected wave signal component subjected to the Doppler shift of the received signal. Divided band pass means configured to select and output from a plurality of received signals passing through the plurality of partial band pass sections is provided, and each partial band pass section is also used as the signal attenuating means.It was.
[0019]
  ThereforeA reflected wave as a Doppler signal component that is substantially a sine wave by selecting and outputting from a plurality of received signals that pass through a plurality of partial band passing portions of the divided band passing means provided in the wave receiving means Based on the signal component, the relative movement speed of the object relative to the apparatus can be calculated. Since the partial band pass section is also used as the signal attenuating means, the specific signal component is selectively attenuated, and the signal level in the signal processing circuit in the divided band pass means or in the subsequent stage is brought to a saturation level. Under the condition that it does not reach, the upper limit of the amplification degree of the received signal and the transmission level of the transmission means can be increased.
Moreover, the above selection is made to select the one with the highest frequency.
Therefore, the ultrasonic wave reflected from the ball can be selected instead of the ultrasonic wave reflected from the pitcher. This is because when the frequency of the ultrasonic wave reflected from the pitcher and the ultrasonic wave reflected from the ball are compared, the frequency of the ultrasonic wave reflected from the ball is high (the Doppler frequency is high).
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to a speed measuring device that measures the moving speed of an object using the Doppler effect of an ultrasonic wave reflected from a moving object such as a baseball will be described.
[0024]
Embodiment 1
FIG. 1 is a block diagram of a speed measuring apparatus according to this embodiment. The velocity measuring device includes an ultrasonic wave transmission unit 10 as a wave transmission unit, an ultrasonic wave reception unit 20 as a wave reception unit, and a signal processing unit 30.
[0025]
The ultrasonic wave transmission unit 10 transmits the ultrasonic wave generated by the wave transmitter 11 based on a reference signal having a predetermined frequency Fo toward a ball 50 as an object moving so as to approach at a moving speed V. A transmitter 11 composed of an ultrasonic transducer or the like for converting an electrical signal into an ultrasonic wave, a reference oscillator 12 for generating a reference signal of a predetermined frequency Fo, and a reference signal necessary for driving the transmitter The output amplifier 13 is configured to amplify to the level.
[0026]
The ultrasonic wave receiving unit 20 receives an ultrasonic wave reflected from the ball 50 by a wave receiver 21 to obtain a received signal, and extracts a Doppler signal component in the received signal. A receiver 21 composed of an ultrasonic transducer or the like for conversion into an electrical signal, a preamplifier 22 for amplifying a weak received signal output from the receiver 21, and a reflected wave signal of frequency Fi output from the amplifier 22 Mixer 23 serving as a mixer for mixing the received signal including the component and the reference signal having the frequency Fo, and the difference (frequency) between the reflected wave signal component subjected to Doppler shift from the signal output from mixer 23 and the reference signal Fd) is constituted by a low-pass filter 24 or the like as band-pass means for selectively passing Fd) as a Doppler signal component.
[0027]
Further, between the receiver 21 and the preamplifier 22, as a signal attenuating means for selectively attenuating a signal component having the same frequency as the reference signal, the center frequency of the attenuation band is set to the frequency Fo of the reference signal. A notch filter 25 which is a band rejection filter is provided. The notch filter 25 is configured by combining in parallel, for example, a low-pass filter and a high-pass filter having the same cutoff frequency, and can obtain a characteristic having a relatively high Q. The attenuation rate for the fundamental wave signal component of the notch filter 25 is set so that predetermined signal processing can be performed in the subsequent circuit. For example, it is set based on the maximum allowable input level for the fundamental wave signal components of the preamplifier 22 and the mixer 23. More specifically, when the gain of the preamplifier 22 is 400 times and the maximum allowable output level (amplitude) is 4 Vpp, the fundamental wave signal component in the received signal input from the wave receiver 21 to the preamplifier 22. Since the preamplifier 22 is saturated when the level of is higher than 10 mVpp, the attenuation factor of the notch filter 25 is set so that the level of the fundamental wave signal component can be attenuated to less than 10 mVpp by the notch filter 25. When the maximum allowable input level of the mixer 23 is smaller than the maximum allowable output level of the preamplifier 22, the level of the fundamental wave signal component input to the mixer 23 is set to the maximum value in consideration of the gain of the preamplifier. The attenuation factor of the notch filter 25 is set so as to be less than the allowable input level. In this case, the notch filter 25 may be provided between the preamplifier 22 and the mixer 23, or the notch filter 25 may be provided at both the front and rear stages of the preamplifier 22.
[0028]
The signal processing unit 30 measures the frequency Fd of the differential signal component as the Doppler signal component output from the low pass filter 24, and determines the moving speed V of the ball 50 from the frequency measurement result of the differential signal component. It comprises a computing unit 32 as speed computing means for computing, a display unit 33 comprising a liquid crystal panel or the like for displaying the measurement result of the speed V, and the like. The calculator 32 calculates the moving speed V of the ball 50 based on the following equation (1). In addition, C in (1) Formula has shown the speed of sound.
[Expression 1]
Fd = 2 · V · Fo / (C−V) (1)
[0029]
The signal processing unit 30 may be provided with a temperature measuring instrument that is used to correct sound velocity fluctuations due to air temperature. This correction can be performed based on the following equation (2), for example. In addition, t in (2) Formula has shown the outside air temperature measured with a temperature measuring device.
[Expression 2]
C = 331.5 + 0.6 · t (2)
[0030]
FIG. 2 is an explanatory diagram showing the intensity (level) of the signal component of each frequency (Fo, Fi, Fd) at a plurality of points (points A to D) in the ultrasonic wave receiving unit 20 of the velocity measuring device having the above configuration. is there. Hereinafter, the signal component of the frequency Fo in the received signal is referred to as a fundamental wave signal component, the signal component of the frequency Fi is referred to as a reflected wave signal component, and the signal component of the frequency Fd (= Fi−Fo) is referred to as a differential signal component. The range of the code DRmix in FIG. 2 indicates the dynamic range of the mixer 23, and the broken line of the code Flp indicates the characteristics of the low-pass filter 24.
[0031]
The voltage amplification degree (gain) Gamp of the preamplifier 22 of the speed measuring device having the above configuration is 200 times, the noise level of the mixer 23 is 2 mV, the saturation level of the mixer 23 is 1 V, and the attenuation rate with respect to the fundamental wave signal component of the notch filter 25. Is 1/200. In this configuration, the level of the reflected wave signal component (Fi) reflected from the ball 50 at point A in FIG. 1 is 100 μV, and the level of the fundamental wave signal component (Fo) due to the direct wave from the transmitter 11 is 5 mV. Then, the level of the fundamental wave signal component (Fo) at the point B is attenuated to 25 μV (= 5 mV / 200) by the notch filter 25, and becomes 5 mV below the saturation level of the mixer 23 after passing through the preamplifier 22 at the point C. . That is, in the case of a conventional device not provided with a notch filter, when the level of the fundamental wave signal component (Fo) at point B is 5 mV, the saturation level of mixer 23 has reached 1 V after passing through preamplifier 22 at point C. However, in the case of the apparatus provided with the notch filter of the present embodiment, the level of the fundamental wave signal component (Fo) after passing through the preamplifier 22 at the point C is sufficiently small as 5 mV, and the normal operating range of the mixer 23 Inside.
(Hereinafter, blank space)
[0032]
On the other hand, the reflected wave signal component (Fi) is not affected by the notch filter 25 and is amplified by the preamplifier 23 to 20 mV within the dynamic range DRmix of the mixer 23. Then, the difference signal component (Fd) as the Doppler signal component is extracted from the received signal output from the mixer 23 at the point D by the low-pass filter 24 having the characteristic indicated by the reference symbol Flp in FIG. The difference signal component (Fd) is input to the signal processing unit 30, the speed of the ball 50 is calculated by the calculator 32 based on the measurement result of the frequency Fd by the frequency measuring instrument 31, and the result is displayed on the display 33. The
[0033]
FIGS. 3A and 3B are explanatory diagrams illustrating a configuration example of the ultrasonic wave transmission unit 10. 3, the output amplifier 13 includes an amplifier 13a that amplifies the reference signal and a coil that forms a series resonance circuit 110 together with the ultrasonic transducer 11a of the transmitter 11. And an inductive impedance element 131.
[0034]
The series resonance circuit 110 attenuates or blocks signal components other than the same frequency as the reference signal included in the output signal from the amplifier 13a, and converts the reference signal component that is substantially a sine wave into the ultrasonic transducer. The resonance frequency is set to the same frequency as the reference signal so that it can be applied to 11a. As a result, the ultrasonic transducer 11a can be driven by the reference signal component which is substantially a sine wave.
[0035]
3A, the series resonance circuit 13b includes the inductive impedance element 131 and the ultrasonic transducer 11a connected in series to the inductive impedance element 131. Has been. The resonance frequency f1 of the series resonance circuit 13b in FIG. 3A is expressed by the following equation (3), where Cs is the capacitance of the ultrasonic transducer 11a and L1 is the inductance of the inductive impedance element 131.
[0036]
[Equation 3]

[0037]
The inductance L1 of the inductive impedance element 131 is set so that the resonance frequency f1 is the same frequency as the frequency Fo of the reference signal. At this resonance frequency, the impedance of the circuit is the smallest and the signal level for driving the ultrasonic transducer is the highest.
[0038]
However, the vibration part of the ultrasonic transducer 11a has a structure in which electrodes are formed on a piezoelectric ceramic, and its capacitance Cs varies depending on environmental conditions, for example, temperature. For this reason, even if the resonance frequency f1 is set to be equal to the frequency Fo of the reference signal at room temperature, the resonance frequency f1 may be deviated from the frequency Fo of the reference signal due to temperature fluctuation. As a result, a sufficient signal level for driving the ultrasonic transducer cannot be obtained, and the transmission level of the sound wave transmitted by the ultrasonic transducer 11a may be reduced.
[0039]
FIG. 3B shows an example of the ultrasonic wave transmission unit 10 that has been improved to prevent the decrease in the transmission level due to the fluctuation of the capacitance Cs of the ultrasonic transducer 11a due to such environmental conditions. Is. In the ultrasonic wave transmission unit 10, a capacitor 133 is connected in parallel with the ultrasonic transducer 11a. As the capacitor 133, a capacitor whose capacitance is less likely to fluctuate than the ultrasonic transducer 11a, such as a film capacitor, can be used. The resonance frequency f2 of the series resonance circuit 111 configured using the capacitor 133, the inductive impedance element 131 of the output amplifier 13, and the ultrasonic transducer 11a is set equal to the frequency Fo of the reference signal. The inductance L2 of the inductive impedance element 131 is set. That is, when the capacitance of the capacitor 133 is C1, the inductance L2 is set so as to satisfy the following expression (4).
[0040]
[Expression 4]

[0041]
When the capacitor 133 is thus connected in parallel to the ultrasonic transducer 11a, the capacitance between the contacts at both ends of the ultrasonic transducer 11a, that is, between the terminal N1 and the ground terminal in FIG. 3B. Is the sum of the capacitance C1 of the capacitor 133 and the capacitance of the ultrasonic transducer 11a. As can be seen from the above equation (4), the resonance frequency f2 is inversely proportional to the 1/2 power of this sum. On the other hand, the resonance frequency f1 of the series resonance circuit of FIG. 3A is inversely proportional to the 1/2 power of the sum of the capacitances of the ultrasonic transducer 11a as shown in the equation (3). For this reason, in the series resonance circuit of FIG. 3B, the ratio that the capacitance Cs of the ultrasonic transducer 11a affects the resonance frequency of the series resonance circuit is smaller than when the capacitor 133 is not connected. That is, even if the capacitance Cs of the vibrator fluctuates due to environmental conditions such as temperature, the rate at which the temperature fluctuation affects the resonance frequency is small. In addition, the capacitance C1 of the capacitor 133 is less likely to vary than the capacitance of the ultrasonic transducer 11a.
[0042]
Therefore, in the ultrasonic velocity measuring apparatus of FIG. 3B, the resonance frequency is less likely to deviate from a desired frequency, that is, the frequency Fo of the reference signal, as compared with the case where the capacitor C1 is not connected. The signal level applied to the child is less likely to fluctuate. Therefore, a sufficient signal level for driving the ultrasonic transducer 11a can be obtained, and a decrease in the transmission level of the sound wave transmitted by the ultrasonic transducer 11a can be prevented.
[0043]
In order to satisfactorily prevent this resonance frequency shift, it is desirable to set the capacitance C1 of the capacitor 133 sufficiently larger than the capacitance Cs of the ultrasonic transducer 11a. Specifically, the capacitance C1 of the capacitor 133 may be set to 5 to 50 times, preferably 10 to 15 times the capacitance Cs of the ultrasonic transducer 11a. With this setting, the resonance frequency f2 is substantially determined by the capacitance C1 of the capacitor and the inductance of the inductive impedance element 132. When the present inventors used the ultrasonic transducer 11a having a capacitance Cs of 2400 pF and a capacitor 133 having a 22000 pF at room temperature, a sufficient transmission level could be stably transmitted.
[0044]
3A and 3B is an amplifier provided separately from the series resonant circuits 110 and 111 in order to amplify the reference signal to a level necessary for driving the transmitter. 13a, the series resonance circuits 110 and 111 amplify the reference signal to a level necessary for driving the transmitter 11, and apply the amplified signal to the ultrasonic transducer 11a of the transmitter 11. You may comprise. Specifically, in the series resonance circuit 110, the signal of the resonance frequency f2 is amplified by “Q of the resonance circuit” and applied to the ultrasonic transducer 11a. The resistance value of the inductive impedance element 131 of the series resonance circuit may be set so that the reference signal can be amplified to a level necessary for driving the transmitter. If the series resonance circuit 110 is configured in this way, it is not necessary to separately provide the amplifier 13a, which is preferable in that the apparatus configuration can be simplified. Further, when the series resonance circuit 110 is configured as described above and the amplifier 13a is provided, a sufficient transmission level can be secured even if the signal level from the reference oscillator 12 is reduced. It becomes. Therefore, low voltage operation can be realized. In order to amplify the signal at the resonance frequency by the series resonance circuit by “Q” of the resonance circuit, it is necessary that the output impedance of the circuit preceding the resonance circuit is sufficiently low. When the amplifier is provided, it is preferable to use the amplifier 13a having a sufficiently low output impedance. When the amplifier 13a is not provided, a buffer circuit having a sufficiently low output impedance may be provided before the resonance circuit.
[0045]
FIG. 4 is an explanatory diagram showing another example of the ultrasonic transmission unit 10. The ultrasonic transmission unit 10 includes a boosting transformer 14 that boosts the output signal from the reference transmitter. Specifically, the output signal is input to the primary coil of the boosting transformer 14, and the secondary coil is connected to the ultrasonic transducer 11a. The ratio of the number of turns of the primary side coil and the secondary side coil of the transformer is 1: n. Further, in this ultrasonic wave transmission unit 10 as well, in the same way as in the case of the ultrasonic wave transmission unit 10 in FIG. In addition, a capacitor 134 is connected in parallel to the ultrasonic transducer 11a. Then, when the transformer is viewed from the secondary side, equivalent inductance L2 of the coil (hereinafter referred to as transformer inductance) L2, the capacitor 134, and the capacitance Cs of the ultrasonic transducer 11a when converted into one coil is equivalent. The inductance L2 of the transformer is set so that the resonance frequency f3 of the series resonance circuit constituted by the above becomes equal to the frequency Fo of the reference signal. Specifically, when the capacitance of the capacitor 134 is C2, the inductance L2 of the transformer is set so as to satisfy the following equation (5).
[0046]
[Equation 5]

[0047]
Thereby, similarly to the ultrasonic wave transmission unit 11 of FIG. 3B, a sufficient signal level for driving the ultrasonic transducer 11a can be obtained, and the sound wave transmitted by the ultrasonic transducer 11a. It is possible to prevent the transmission level of the signal from becoming small.
[0048]
In addition, in the ultrasonic wave transmission unit 11 of FIG. 4, the signal level of the reference signal can be amplified n times by the step-up transformer 14, so that the reference signal can be transmitted with a simple configuration. 11 can be amplified to a level necessary for driving.
Further, in the ultrasonic transmission unit 11, if the series resonance circuit is configured so that the Q of the resonance circuit becomes a value that can amplify the reference signal to a level necessary for driving the transmitter, Even if the signal level from the reference oscillator 12 is reduced, a sufficient transmission level can be secured. Therefore, further low voltage operation can be realized.
[0049]
As described above, according to the velocity measuring apparatus according to the present embodiment, the amplification factor and the transmitter of the preamplifier 22 are provided under the condition that the preamplifier 22 and the mixer 23 located downstream of the notch filter 25 do not reach the saturation level. 11 can increase the upper limit of the transmission level of 11, so that even if there is a direct wave wraparound from the transmitter 11 to the receiver 21 or reflection of ultrasonic waves from a stationary object near the ball 50. It is possible to accurately measure the speed of the ball 50 that is an object that is small and far from the apparatus.
[0050]
Further, in the velocity measuring apparatus according to the present embodiment, as the ultrasonic transmission unit 10, an ultrasonic transducer 11a having a capacitance component and a signal having the same frequency Fo as the reference signal are selectively used as the ultrasonic transducer. An inductive impedance element that, together with the ultrasonic transducer 11a, constitutes a series resonant circuit in which the resonance frequency is set to the same frequency Fo as that applied to the ultrasonic transducer 11a to drive the ultrasonic transducer 11a. In the case of using the ultrasonic transducer 11a that transmits the ultrasonic wave by driving the ultrasonic transducer 11a, as shown in FIG. 3B or FIG. In parallel with the transducer 11a, a capacitor whose capacitance is less likely to fluctuate depending on environmental conditions than the ultrasonic transducer is connected, and the inductive impedance element, the capacitor, and It is desirable to set the inductance of the inductive impedance elements so that the resonance frequency is equal to the frequency Fo of the reference signal of the series resonant circuit formed by using the ultrasonic transducer 11a. By adopting such a configuration, a sufficient signal level for driving the ultrasonic transducer 11a can be obtained, and the transmission level of the sound wave transmitted by the ultrasonic transducer 11a can be prevented from being reduced. can do.
[0051]
[Embodiment 2]
FIG. 5 is a block diagram of a speed measuring device according to another embodiment of the present invention. The configuration of the ultrasonic wave transmission unit 10, the ultrasonic wave reception unit 20 from the wave receiver 21 to the mixer 23, and the signal processing unit 30 of the velocity measuring device are the same as the configuration of FIG. 1 described above. Since there are, description of them will be omitted. The signal processing unit 30 of the present apparatus is provided with a temperature measuring instrument 34 used for correcting the sound speed fluctuation due to the temperature.
[0052]
In the apparatus shown in FIG. 1, the reflected wave entering the receiver 21 may not be a single frequency component. That is, if there is only one object that generates the reflected wave, such as a car or a ball flying in the air, the frequency of the reflected wave that has undergone Doppler shift reflected from those objects is one. The extracted Doppler signal component is a sine wave. However, in the case of measuring the initial velocity of the ball thrown by the pitcher, for example, as shown in FIG. 6 (a), a reflected wave signal component that has received a Doppler shift having a different frequency from any part of the pitcher's arm or body other than the ball. Sound waves including Fi1 to Fi5 are reflected. When a sound wave including a plurality of reflected wave signal components Fi1 to Fi5 having different frequencies is received as described above, the waveform of the received signal Fi is distorted as shown in FIG. is there.
[0053]
Therefore, in this embodiment, instead of the low-pass filter 24 that passes all of the difference signal components Fd1 to Fd5 corresponding to the plurality of reflected wave signal components, the frequency band that the difference signal component can take is divided into a plurality of parts. A division configured to have a plurality of partial band passing portions each having a pass band set in each of the partial bands, and to select and output from a plurality of differential signal components passing through the plurality of partial band passing portions. Band pass means are provided.
[0054]
The divided band pass means includes a filter group 26 including five band pass filters BPF as the partial band pass unit, and a detector group 27 including five signal detectors for detecting signals that have passed through each BPF, The signal selector 28 selects one signal from the signals output from each signal detector as a differential signal component for calculating the velocity V.
[0055]
The band pass filter group 26 is divided into five pass bands (HH, HL, M, LH, LL) from the high frequency side, and the differential signal component input from the mixer 23 is converted into each band signal Se (SeHH to SeLL). And output to the signal detector group 27 and the signal selector 28. Here, when the frequency Fo of the reference signal is 32.768 kHz and the measurement speed range is 10 to 200 km / h, the frequency Fd of the differential signal component as the Doppler signal component is 530 Hz to 12.5 kHz according to the above equation (1). Therefore, for example, the center frequencies of the five BPF1 to BPF5 may be set to 1.5 kHz, 3.5 kHz, 5.5 kHz, 9.5 kHz, and 11.5 kHz, respectively, and the passband width may be set to 2 kHz. (See FIG. 6 (c)). The number of bandpass filters BPF and signal detectors is not limited to five, but is determined according to the measurement speed range and the required measurement accuracy.
[0056]
The signal detector group 27 detects a band signal having a signal level larger than a threshold set in advance in each signal detector among the band signals Se output from the bandpass filter group 26 as a detection signal having a superior level. The signal is output to the signal selector 28 as Sf.
[0057]
The signal selector 28 selects the detection signal Sh having the highest frequency from the detection signal Sf having the superiority level and outputs the detection signal Sh to the frequency measuring device 31. Here, the reason why the signal having the highest frequency is selected from the plurality of detection signals Sf is, for example, when the frequencies of the ultrasonic wave reflected from the pitcher and the ultrasonic wave reflected from the ball 50 are compared, reflected from the ball. This is because the ultrasonic frequency is high (the Doppler frequency is high). In addition, when the relationship between the ultrasonic wave reflected from the object and the ultrasonic wave not intended is not the above-described relationship, a criterion for selection by the signal selector 28 may be appropriately set.
[0058]
Several methods are conceivable as to which band pass filter BPF is selected by the signal selector 28. For example, when a plurality of signals are output simultaneously from the signal detector as in the present embodiment, a method of selecting a signal that has passed through the BPF having the highest center frequency, or the signal detector output first. There is a method of selecting a signal.
[0059]
FIG. 7 is a block diagram of another example of the speed measuring device according to the present embodiment. In this speed measuring apparatus, the divided band pass means is configured using an analog / digital converter for converting an analog signal into a digital signal and a digital signal processing means. Specifically, an analog / digital converter (hereinafter referred to as an AD converter) is used instead of the filter group 26, the detector group 27, the signal selector 28, the frequency measuring device 31, and the arithmetic unit 32 in the velocity measuring device of FIG. 61) and a DSP 62 as a digital signal processing means for processing a digital signal, having the functions of the filter group 26, the detector group 27, the signal selector 28, the frequency measuring device 31, and the arithmetic unit 32. Yes. As the digital signal processing means, an IC for digital signal processing integrated on one chip other than the DSP 62, for example, a microcomputer may be used.
[0060]
The AD converter 61 converts the analog signal output from the mixer 23 into a digital signal. In the DSP 62, for example, by performing digital filter processing such as Fourier transform, it is possible to obtain the same operation as the filter group.
[0061]
Then, after performing the filtering process, a frequency is obtained for a digital signal obtained by performing a signal detection process and a signal selection process, and the moving speed V of the ball 50 is calculated.
[0062]
The function of the DSP 62 as the digital signal processing means is not limited to the functions of the filter group 26, the detector group 27, the signal selector 28, the frequency measuring device 31, and the arithmetic unit 32. The range may be appropriately selected according to the processing capability of the digital signal processing means.
[0063]
As described above, according to the velocity measuring apparatus according to the present embodiment, the direct wave wraps around from the transmitter 11 to the receiver 21 and the superposition from the stationary object in the vicinity of the ball 50, as in the apparatus of FIG. Even when there is reflection of sound waves, the speed of the ball 50, which is an object that is small and far from the apparatus, can be measured with high accuracy. In addition, since the velocity of the ball 50 can be calculated based on the differential signal component that is substantially a sine wave as the Doppler signal component, a plurality of ultrasonic waves having different frequencies other than the reflected wave from the ball 50 are simultaneously received. The occurrence of erroneous measurement when waved can be suppressed.
[0064]
[Embodiment 3]
FIG. 8 is a block diagram of a speed measuring device according to still another embodiment of the present invention. Since the configuration of the ultrasonic wave transmission unit 10, a part of the ultrasonic wave reception unit 20, and the signal processing unit 30 of the speed measurement device are the same as the configuration of FIG. 5 described above, description thereof will be omitted.
[0065]
In the present embodiment, the notch filter 25 provided in the rear stage of the preamplifier 22 is not provided with the mixer 23 used in the apparatus of FIG. 5, and the reflected wave signal component in the received signal input to the bandpass filter group 26 is used. Is configured to pass through. The attenuation rate of the notch filter 25 with respect to the fundamental wave signal component is a magnitude that does not affect the signal processing in those circuits in consideration of the saturation characteristics in the band-pass filter group 26 in the subsequent stage and the frequency measurement capability in the frequency measuring device 31. Set to. For example, the level ratio of the reflected wave signal component and the fundamental wave signal component on the output side of the preamplifier 22 is approximately 1: 1, and the reflected wave signal component and the noise component (fundamental wave signal) necessary for the measurement by the frequency measuring device 31 are used. When the level ratio (including the component) is 4 to 1, the attenuation rate of the notch filter 25 with respect to the fundamental wave signal component is set to 1/4, that is, -12 dB. If signal saturation in the preamplifier 22 is also a problem, a notch filter is provided between the receiver 21 and the preamplifier 22, or a notch filter is provided at both the front and rear stages of the preamplifier 22. May be provided.
[0066]
In the case of the apparatus using the mixer 23 of FIG. 5, the pass band of the bandpass filter group 26 is 530 Hz to 12.5 kHz beat-down. However, in the case of the apparatus of FIG. The bandpass filter group 26 may be configured by dividing the frequency band 33.3 kHz to 45.7 kHz that can be taken by the previous reflected wave signal component into a plurality of parts.
[0067]
8 employs a configuration in which the velocity is calculated using the frequency of the reflected wave signal component instead of the frequency of the differential signal component. Specifically, the signal processing unit 30 may be configured to calculate the moving speed V of the ball 50 based on an equation obtained by substituting Fd = Fi−Fo into the above equation (1).
[0068]
Also in the speed measuring device according to the present embodiment, similarly to the speed measuring device of FIG. 7, the bandpass filter group 26 as the divided band passing means includes an analog / digital converter that converts an analog signal into a digital signal, and a digital signal. You may comprise using a signal processing means. FIG. 9 is a block diagram showing an example of a speed measuring device adopting such a configuration. In the apparatus of FIG. 9, an analog / digital converter (hereinafter referred to as AD) is used in place of the filter group 26, the detector group 27, the signal selector 28, the frequency measuring device 31, and the computing unit 32 in the velocity measuring device of FIG. 61) and the DSP 62 as a digital signal processing means for processing a digital signal, which has the functions of the filter group 26, the detector group 27, the signal selector 28, the frequency measuring device 31, and the arithmetic unit 32. Provided. As the digital signal processing means, an IC for digital signal processing integrated on one chip other than the DSP 62, for example, a microcomputer may be used.
[0069]
The AD converter 61 converts the analog signal output from the notch filter 25 into a digital signal. In the DSP 62, for example, by performing digital filter processing such as Fourier transform, it is possible to obtain the same operation as the filter group.
[0070]
Then, after performing the filtering process, a frequency is obtained for a digital signal obtained by performing a signal detection process and a signal selection process, and the moving speed V of the ball 50 is calculated.
[0071]
In the present embodiment, the DSP 62 as the digital signal processing means has the same functions as the filter group 26, the detector group 27, the signal selector 28, the frequency measuring device 31, and the arithmetic unit 32. The range is not limited, and the range may be appropriately selected according to the processing capability of the digital signal processing means.
[0072]
As described above, according to the velocity measuring device according to the present embodiment, the direct wave sneak from the transmitter 11 to the receiver 21 or the ultrasonic wave from a stationary object in the vicinity of the ball 50 without providing a mixer. Even if there is a reflection, it is possible to accurately measure the velocity of the ball 50, which is a small object far from the apparatus, and simultaneously receive a plurality of ultrasonic waves having different frequencies other than the reflected wave from the ball 50. The occurrence of erroneous measurement when waved can be suppressed. Moreover, unlike the case where the difference between the reflected wave signal component output from the mixer 23 and the reference signal is used as the Doppler signal component, the ball 50 is formed based on the frequency value of the reflected wave signal component used as the Doppler signal component. The speed of the ball 50 can be measured by distinguishing whether the ball is approaching or moving away.
[0073]
[Embodiment 4]
FIG. 10 is a block diagram of a speed measuring device according to still another embodiment of the present invention. Since the configuration of the ultrasonic wave transmission unit 10, a part of the ultrasonic wave reception unit 20, and the signal processing unit 30 of the speed measurement device are the same as the configuration of FIG. 5 described above, description thereof will be omitted.
(Hereinafter, blank space)
[0074]
In this embodiment, the mixer 23 and the notch filter 25 used in the apparatus of FIG. 5 are not provided, but each BPF of the bandpass filter group 26 has a function of a notch filter that attenuates the fundamental wave signal component of the frequency fo. It is That is, the selectivity (Q) of each BPF is increased so as to attenuate the fundamental wave signal component to a required level. The attenuation rate with respect to the fundamental wave signal component of each BPF is set to a size that does not affect the frequency measurement in consideration of the frequency measurement capability and the like in the frequency measuring device 31 in the subsequent stage. For example, the level ratio of the reflected wave signal component and the fundamental wave signal component on the output side of the preamplifier 22 is approximately 1: 1, and the reflected wave signal component and the noise component (fundamental wave signal) necessary for the measurement by the frequency measuring device 31 are used. (Including components) is 4 to 1, the attenuation rate of each BPF with respect to the fundamental signal component is set to 1/4, that is, -12 dB.
[0075]
In the case of the configuration of the present embodiment, it is preferable to suppress the gain of the preamplifier 22 to such an extent that the signal is not saturated in the band pass filter group 26. As for the shortage of gain, each BPF of the bandpass filter group 26 may have as much gain as necessary.
[0076]
Also, the velocity measuring device of FIG. 10 employs a configuration in which the velocity is calculated using the frequency of the reflected wave signal component, not the frequency of the differential signal component, as in the velocity measuring device of FIG. . Specifically, the signal processing unit 30 may be configured to calculate the moving speed V of the ball 50 based on an equation obtained by substituting Fd = Fi−Fo into the above equation (1).
[0077]
Also in the speed measuring device according to the present embodiment, similarly to the speed measuring device of FIG. 7, the bandpass filter group 26 as the divided band passing means includes an analog / digital converter that converts an analog signal into a digital signal, and a digital You may comprise using a signal processing means. FIG. 11 is a block diagram showing an example of a speed measuring device adopting such a configuration. In the apparatus of FIG. 11, an analog / digital converter (hereinafter referred to as AD) is used instead of the filter group 26, the detector group 27, the signal selector 28, the frequency measuring device 31, and the arithmetic unit 32 in the velocity measuring device of FIG. 61) and the DSP 62 as a digital signal processing means for processing a digital signal, which has the functions of the filter group 26, the detector group 27, the signal selector 28, the frequency measuring device 31, and the arithmetic unit 32. Provided. As the digital signal processing means, an IC for digital signal processing integrated on one chip other than the DSP 62, for example, a microcomputer may be used.
[0078]
The AD converter 61 converts the analog signal output from the preamplifier 22 into a digital signal. In the DSP 62, for example, by performing digital filter processing such as Fourier transform, it is possible to obtain the same operation as the filter group.
[0079]
Then, after performing the filtering process, a frequency is obtained for a digital signal obtained by performing a signal detection process and a signal selection process, and the moving speed V of the ball 50 is calculated.
[0080]
In the present embodiment, the DSP 62 as the digital signal processing means has the same functions as the filter group 26, the detector group 27, the signal selector 28, the frequency measuring device 31, and the arithmetic unit 32. The range is not limited, and the range may be appropriately selected according to the processing capability of the digital signal processing means.
[0081]
As described above, according to the velocity measuring apparatus according to the present embodiment, the direct wave from the transmitter 11 to the receiver 21 can be provided as in the apparatus of FIG. 8 without providing a mixer or independently providing a notch filter. Even if there is a wraparound or reflection of ultrasonic waves from a stationary object in the vicinity of the ball 50, the speed of the ball 50, which is a small object far from the apparatus, can be measured with high accuracy. It is possible to suppress the occurrence of erroneous measurement when a plurality of ultrasonic waves having different frequencies other than the reflected wave from 50 are received simultaneously. Moreover, unlike the case where the difference between the reflected wave signal component output from the mixer 23 and the reference signal is used as the Doppler signal component, the ball 50 approaches based on the frequency value of the reflected wave signal component used as the Doppler signal component. The speed of the ball 50 can be measured by distinguishing whether the ball is moving or moving away.
[0082]
In the velocity measuring device according to each of the second to fourth embodiments, the ultrasonic wave transmission unit 10 shown in FIGS. 3A, 3B, and 4 can be used. Also in the velocity measuring device according to each of the second to fourth embodiments, the ultrasonic transducer 11a having a capacitance component and the signal having the same frequency Fo as the reference signal are selectively used as the ultrasonic transmission unit 10. A series resonance circuit in which a resonance frequency is set to the same frequency Fo as the reference signal so as to be applied to the ultrasonic transducer 11a to drive the ultrasonic transducer 11a is configured with the ultrasonic transducer 11a. In the case of using the one having an impedance element and transmitting the ultrasonic wave by driving the ultrasonic transducer 11a, as in the example of FIG. 3B or FIG. In addition, a capacitor whose capacitance is less likely to fluctuate depending on environmental conditions is connected in parallel with the ultrasonic transducer 11a as compared with the ultrasonic transducer, and the inductive impedance element Capacitors, and, to set the inductance of the inductive impedance elements so that the resonance frequency of the series resonant circuit formed by using the ultrasonic transducer 11a is equal to the frequency Fo of the reference signal is desired. By adopting such a configuration, a sufficient signal level for driving the ultrasonic transducer 11a can be obtained, and the transmission level of the sound wave transmitted by the ultrasonic transducer 11a can be prevented from being reduced. can do.
[0083]
Further, in each of the first to fourth embodiments described above, the object for transmitting sound waves is a ball and the object for measuring the velocity of the ball has been described. However, the object is not limited to a ball. Absent. The present invention includes the present apparatus on the side of a moving object such as an automobile moving on a stationary object such as a road, and measures the relative moving speed of the object, that is, the moving speed of the moving object including the apparatus. It can be applied to various speed measuring devices.
[0084]
Further, the configurations of the wave transmission means and the signal processing means are not limited to the configurations of the ultrasonic wave transmission unit 10 and the signal processing unit 30 of the above-described embodiments, and the present invention is not limited to the wave transmission units of other configurations. In addition, the present invention can also be applied when a signal processing means is employed.
[0085]
【The invention's effect】
  Claims 1 to5According to the invention, the amplification level of the received signal and the upper limit of the transmission level of the transmission means under the condition that the signal level of the signal processing circuit in the subsequent stage of the signal attenuation means in the reception means does not reach the saturation level. Therefore, even if there is a wraparound of sound waves from the transmitting means to the receiving means or reflection of sound waves from a stationary object near the object, Relative speed can be measured with high accuracy.
[0086]
  In particular, the claims1According to the invention, the amplification level of the received signal and the transmission level of the transmission means are adjusted under the condition that the signal level of the signal processing circuit such as an amplifier or a mixer downstream from the signal attenuation means does not reach the saturation level. The upper limit can be increasedThe
[0087]
  In particular, the claims2According to this invention, the upper limit of the amplification degree of the received signal and the transmission level of the transmission means is set under the condition that the signal level of the signal processing circuit such as a mixer subsequent to the signal attenuation means does not reach the saturation level. Can be highThe
[0088]
  In particular, the claims1 or 2According to the invention, since the relative moving speed of the object with respect to the present apparatus can be calculated based on the difference signal component that is substantially a sine wave as the Doppler signal component, the difference is different from the reflected wave from the object. It is possible to suppress the occurrence of erroneous measurement when multiple sound waves with frequencies are received simultaneously.The
[0089]
  In particular, the claims3According to this invention, without providing a mixer for mixing the reference signal and the received signal, the amplification level and transmission rate of the received signal can be obtained under the condition that the signal level of the signal processing circuit in the receiving means does not reach the saturation level. The upper limit of the transmission level of the wave means can be increased, and the occurrence of erroneous measurement when reflected wave signal components subjected to Doppler shift of different frequencies are simultaneously received can be suppressed. In addition, unlike the case where the difference between the reflected wave signal component and the reference signal is used as the Doppler signal component, the present apparatus and the object approach based on the frequency value of the reflected wave signal component used as the Doppler signal component. Can be measured separatelyThe
[0090]
  In particular, the claims4According to this invention, it is possible to reliably attenuate only the signal component having the same frequency as the reference signal.The
[0091]
  In particular, the claims5According to the invention, the amplification degree of the received signal and the transmission level of the transmission means are provided under the condition that the signal level of the signal processing circuit in the reception means does not reach the saturation level without providing the signal attenuation means independently. Can be made high, and occurrence of erroneous measurement when reflected wave signal components subjected to Doppler shift of different frequencies are simultaneously received can be suppressed. In addition, unlike the case where the difference between the reflected wave signal component and the reference signal is used as the Doppler signal component, the present apparatus and the object approach based on the frequency value of the reflected wave signal component used as the Doppler signal component. Can be measured separatelyThe
[Brief description of the drawings]
FIG. 1 is a block diagram of a speed measuring device according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing amplitudes (levels) of signal components of respective frequencies (Fo, Fi, Fd) at a plurality of locations (points A to D) in the ultrasonic wave receiving unit 20 of the velocity measuring device configured as described above.
FIGS. 3A and 3B are diagrams showing a configuration example of an ultrasonic wave transmission unit 10 of the velocity measuring device. FIGS.
FIG. 4 is a view showing another configuration example of the ultrasonic transmission unit 10;
FIG. 5 is a block diagram of a speed measuring device according to another embodiment.
FIG. 6A is an explanatory diagram of waveforms of a plurality of reflected wave signal components Fi1 to Fi5 having different frequencies.
(B) is explanatory drawing of the waveform of the signal which synthesize | combined the reflected wave signal component Fi1-Fi5.
(C) is an explanatory view of the filter characteristics and input signals (Fo, Fi, Fd) of the band-pass filter group.
FIG. 7 is a block diagram showing another example of the speed measuring device.
FIG. 8 is a block diagram of a speed measuring device according to still another embodiment.
FIG. 9 is a block diagram showing another example of the speed measuring device.
FIG. 10 is a block diagram of a speed measuring device according to still another embodiment.
[Figure11A block diagram showing another example of the speed measuring apparatus.
FIG. 12 is a block diagram of a speed measuring device according to a conventional example.
FIG. 13 is an explanatory diagram of a dynamic range of a preamplifier and a mixer in the velocity measuring apparatus.
[Explanation of symbols]
10 Ultrasonic wave transmitter
11 Transmitter
11a Ultrasonic vibrator
20 Ultrasonic wave receiver
21 Receiver
22 Preamplifier
23 Mixer
24 Low-pass filter
25 Notch filter
26 Bandpass filters
27 Signal detector group
28 Signal selector
30 Signal processor
31 Frequency measuring instrument
32 Calculator
33 Display
50 balls
131, 132 Inductive impedance element
133 capacitor
134 capacitors
14 transformer

Claims (5)

A wave transmitting means for transmitting a sound wave generated based on a reference signal of a predetermined frequency toward an object, and a sound wave reflected from the object is received as a received signal, and a Doppler signal component in the received signal A pitching ball speed measuring device comprising: a wave receiving means for extracting a wave; and a speed calculating means for calculating a relative moving speed of the object with respect to the apparatus based on the Doppler signal component.
The signal receiving means is provided with a signal attenuation means for selectively attenuating a signal component having the same frequency as the reference signal,
The wave receiving means includes a wave receiver for receiving a sound wave reflected from the object, an amplifier for amplifying a reception signal output from the wave receiver, a reception signal output from the amplifier, and the reference A mixer for mixing the signals, and band-pass means for selectively passing the difference between the reflected wave signal component subjected to Doppler shift from the signal output from the mixer and the reference signal as the Doppler signal component. Configured with
The signal attenuation means is provided between the receiver and the amplifier;
The band passing means has a plurality of partial band passing portions each having a pass band set in each of the partial bands obtained by dividing the frequency band that can be taken by the differential signal component, and passes through the plurality of partial band passing portions. A pitching ball velocity measuring device configured to select and output the highest frequency component from a plurality of differential signal components. A wave transmitting means for transmitting a sound wave generated based on a reference signal of a predetermined frequency toward an object, and a sound wave reflected from the object is received as a received signal, and a Doppler signal component in the received signal A pitching ball speed measuring device comprising: a wave receiving means for extracting a wave; and a speed calculating means for calculating a relative moving speed of the object with respect to the apparatus based on the Doppler signal component.
The signal receiving means is provided with a signal attenuation means for selectively attenuating a signal component having the same frequency as the reference signal,
The wave receiving means includes a wave receiver for receiving a sound wave reflected from the object, an amplifier for amplifying a reception signal output from the wave receiver, a reception signal output from the amplifier, and the reference A mixer for mixing the signals, and band-pass means for selectively passing the difference between the reflected wave signal component subjected to Doppler shift from the signal output from the mixer and the reference signal as the Doppler signal component. Configured with
The signal attenuation means is provided between the amplifier and the mixer;
The band passing means has a plurality of partial band passing portions each having a pass band set in each of the partial bands obtained by dividing the frequency band that can be taken by the differential signal component, and passes through the plurality of partial band passing portions. A pitching ball velocity measuring device configured to select and output the highest frequency component from a plurality of differential signal components. A wave transmitting means for transmitting a sound wave generated based on a reference signal of a predetermined frequency toward an object, and a sound wave reflected from the object is received as a received signal, and a Doppler signal component in the received signal A pitching ball speed measuring device comprising: a wave receiving means for extracting a wave; and a speed calculating means for calculating a relative moving speed of the object with respect to the apparatus based on the Doppler signal component.
The signal receiving means is provided with a signal attenuation means for selectively attenuating a signal component having the same frequency as the reference signal,
The wave receiving means includes a plurality of partial band passing portions each having a pass band set in each of the partial bands obtained by dividing the frequency band that can be taken by the reflected wave signal component subjected to the Doppler shift of the received signal. Provided with a divided band pass means configured to select and output the highest frequency among a plurality of received signals passing through the plurality of partial band pass portions,
A pitching ball speed measuring device, wherein the signal attenuating means is configured to pass the reflected wave signal component in the received signal inputted to the divided band passing means. In the throwing ball speed measuring device according to claim 1, 2 or 3,
A pitching ball velocity measuring apparatus using a band rejection filter in which a center frequency of an attenuation band is set as a frequency of the reference signal as the signal attenuation means. A wave transmitting means for transmitting a sound wave generated based on a reference signal of a predetermined frequency toward an object, and a sound wave reflected from the object is received as a received signal, and a Doppler signal component in the received signal A pitching ball speed measuring device comprising: a wave receiving means for extracting a wave; and a speed calculating means for calculating a relative moving speed of the object with respect to the apparatus based on the Doppler signal component.
The signal receiving means is provided with a signal attenuation means for selectively attenuating a signal component having the same frequency as the reference signal,
The wave receiving means includes a plurality of partial band passing portions each having a pass band set in each of the partial bands obtained by dividing the frequency band that can be taken by the reflected wave signal component subjected to the Doppler shift of the received signal. Provided with a divided band pass means configured to select and output the highest frequency among a plurality of received signals passing through the plurality of partial band pass portions,
A pitching ball speed measuring device characterized in that each of the partial band passing portions is also used as the signal attenuating means .

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