JP4168459B2

JP4168459B2 - Driving device and driving method for vibration actuator

Info

Publication number: JP4168459B2
Application number: JP16220997A
Authority: JP
Inventors: 聡三輪; 隆利芦沢
Original assignee: Nikon Corp
Current assignee: Nikon Corp
Priority date: 1997-06-19
Filing date: 1997-06-19
Publication date: 2008-10-22
Anticipated expiration: 2017-06-19
Also published as: JPH1118449A

Description

【０００１】
【発明の属する技術分野】
本発明は、振動アクチュエータの速度を、周波数及び電圧によって制御する振動アクチュエータの駆動装置及び駆動方法に関するものである。
【０００２】
【従来の技術】
図７は、従来の振動アクチュエータの駆動方法を示す線図である。
従来の振動アクチュエータは、図７（Ａ）に示すように、駆動周波数ｆのみ変更することにより、回転数の制御をしていた。また、図７（Ｂ）に示すように、電圧値Ｖのみ変更することにより、回転数の制御をしていた。この場合には、２相の電圧値を同時に同じ割合で変更していた。さらに、これらを組み合わせて、制御することもあった。
【０００３】
【発明が解決しようとする課題】
しかし、従来の駆動方法は、速度を増加させようとしたときに、駆動信号の周波数を下げていくことになるが、共振に達した時点で速度は増加しなくなる。
また、速度を増加させるためには、印加電圧の値を上げる必要があるが、この場合に、２相の電圧値を同時に同じ割合で上げていたので、入力が大きく増加してしまうという問題があった。
【０００４】
一方、速度を減少させようとしたときに、駆動信号の周波数を上げていくことになるが、異モード縮退型振動アクチュエータの場合に、クラッチ成分の振動も減少していくために、クラッチ機構の動作が不安定となり、回転ムラが大きくなるという問題があった。
また、２相の電圧値を同時に同じ割合で下げても、同様にクラッチ成分の振動が減少していくために、同様な問題が生じていた。
【０００５】
従って、前記各場合とも、超低速駆動が困難であった。すなわち、効率よく広いダイナミックレンジを実現することが困難であった。
【０００６】
本発明の課題は、超低速駆動から高速駆動まで、効率よく広いダイナミックレンジを実現することを可能とする振動アクチュエータの駆動装置を提供することである。
【０００７】
【課題を解決するための手段】
前記課題を解決するために、請求項１の発明は、第１の電気機械変換素子と第２の電気機械変換素子を有し、前記第１の電気機械変換素子と前記第２の電気機械変換素子とに周波電圧が供給されることにより駆動力を発生する振動子及び前記振動子と接触し前記駆動力により前記振動子との間で相対運動を行なう相対運動部材とを備える振動アクチュエータと、前記第１の電気機械変換素子と前記第２の電気機械変換素子に前記周波電圧を供給する駆動回路とを備え、前記駆動回路は、前記第１の電気機械変換素子と前記第２の電気機械変換素子とに供給する前記周波電圧のそれぞれの電圧値を変化させないで周波数を変更する第１の制御と、前記第２の電気機械変換素子に供給する前記周波電圧の電圧値を変化させないで、前記第１の電気機械変換素子に供給する前記周波電圧の電圧値を変更する第２の制御とを、少なくとも２回切り換えることにより、前記振動子と前記相対運動部材間の相対速度を制御し、前記振動子は、前記第１の電気機械変換素子により、前記振動子と前記相対運動部材との接触面とほぼ平行な面内で振動を発生させ、前記第２の電気機械変換素子により、前記接触面と交差する方向に振動を発生させることにより前記駆動力を得ることを特徴とする振動アクチュエータの駆動装置である。
【０００８】
請求項３の発明は、請求項１又は請求項２に記載された振動アクチュエータの駆動装置において、前記第１の電気機械変換素子は、前記駆動力の方向とほぼ平行な方向に振動する第１の振動を発生させ、前記第２の電気機械変換素子は、前記第１の振動の振動方向と交差する方向に振動する第２の振動を発生させることを特徴とする振動アクチュエータの駆動装置である。
請求項４の発明は、請求項１から請求項３のいずれか１項に記載された振動アクチュエータの駆動装置において、前記駆動回路は、前記第１の制御、前記第２の制御、前記第１の制御の順に各制御を行なうことにより、前記振動子と前記相対運動部材間の相対速度を制御することを特徴とする振動アクチュエータの駆動装置である。
【０００９】
請求項５の発明は、請求項１から請求項４のいずれか１項に記載された振動アクチュエータの駆動装置において、前記駆動回路は、前記第１の制御から前記第２の制御への切り換えは、前記周波電圧の周波数が所定の値に達した時点で行い、前記第２の制御から前記第１の制御への切り換えは、前記第１の電気機械変換素子に供給される周波電圧の電圧値が所定の値に達した時点で行うことを特徴とする振動アクチュエータの駆動装置である。
【００１０】
請求項６の発明は、請求項１から請求項４のいずれか１項に記載された振動アクチュエータの駆動装置において、前記相対運動部材の速度を検出する速度検出器を備え、前記駆動回路は、前記第１の制御から前記第２の制御への切り換えは、前記速度検出器によって検出された前記相対運動部材の速度が第１の値に達した時点で行い、前記第２の制御から前記第１の制御への切り換えは、前記速度検出器によって検出された前記相対運動部材の速度が第２の値に達した時点で行うことを特徴とする振動アクチュエータの駆動装置である。
【００１１】
請求項７の発明は、請求項１から請求項６のいずれか１項に記載された振動アクチュエータの駆動装置において、前記振動子は、前記接触面とほぼ平行な面内で振動するねじり振動を発生させ、前記接触面と交差する方向に縦振動を発生させることにより前記駆動力を得ることを特徴とする振動アクチュエータの駆動装置である。
【００１２】
請求項８の発明は、第１の電気機械変換素子と第２の電気機械変換素子とに周波電圧を供給することにより振動子に駆動力を発生させ、前記駆動力により前記振動子との間で相対運動部材に相対運動を行わせる振動アクチュエータの駆動方法において、前記第１の電気機械変換素子と前記第２の電気機械変換素子とに供給する前記周波電圧のそれぞれの電圧値を変化させないで周波数を変更する第１の制御と、前記第２の電気機械変換素子に供給する前記周波電圧の電圧値を変化させないで、前記第１の電気機械変換素子に供給する前記周波電圧の電圧値を変更する第２の制御とを、少なくとも２回切り換えることにより、前記振動子と前記相対運動部材間の相対速度を制御し、前記第１の電気機械変換素子により、前記振動子と前記相対運動部材との接触面とほぼ平行な面内で振動を発生させ、前期第２の電気機械変換素子により、前記接触面と交差する方向に振動を発生させることによって前記駆動力を得ることを特徴とする振動アクチュエータの駆動方法である。
【００１３】
請求項１０の発明は、請求項８又は請求項９に記載された振動アクチュエータの駆動方法において、前記第１の電気機械変換素子は、前記駆動力の方向とほぼ平行な方向に振動する第１の振動を発生させ、前記第２の電気機械変換素子は、前記第１の振動の振動方向と交差する方向に振動する第２の振動を発生させることを特徴とする振動アクチュエータの駆動方法である。
請求項１１の発明は、請求項８から請求項１０のいずれか１項に記載された振動アクチュエータの駆動方法において、前記第１の制御、前記第２の制御、前記第１の制御の順に行なうことによって前記振動子と前記相対運動部材間の相対速度を制御することを特徴とする振動アクチュエータの駆動方法である。
【００１４】
請求項１２の発明は、請求項８から請求項１１のいずれか１項に記載された振動アクチュエータの駆動方法において、前記第１の制御から前記第２の制御への切り換えは、前記周波電圧の周波数が所定の値に達した時点で行い、前記第２の制御から前記第１の制御への切り換えは、前記第１の電気機械変換素子に供給される周波電圧の電圧値が所定の値に達した時点で行うことを特徴とする振動アクチュエータの駆動方法である。
【００１５】
請求項１３の発明は、請求項８から請求項１１のいずれか１項に記載された振動アクチュエータの駆動方法において、前記相対運動部材の速度を検出し、前記第１の制御から前記第２の制御への切り換えは、検出された前記相対運動部材の速度が第１の値に達した時点で行い、前記第２の制御から前記第１の制御への切り換えは、検出された前記相対運動部材の速度が第２の値に達した時点で行うことを特徴とする振動アクチュエータの駆動方法である。
【００１６】
請求項１４の発明は、請求項８から請求項１３のいずれか１項に記載された振動アクチュエータの駆動方法において、前記接触面とほぼ平行な面内で振動するねじり振動を発生させ、前記接触面と交差する方向に振動する縦振動を発生させることによって前記駆動力を得ることを特徴とする振動アクチュエータの駆動方法。
【００１７】
請求項１５の発明は、請求項１から請求項７のいずれか１項に記載の振動アクチュエータの駆動装置において、前記駆動回路は、前記相対運動の速度を所望の速度に設定できるように設けられた速度可変領域を、速度の高い側から第１の領域、第２の領域、第３の領域に分け、前記第１及び第３の領域では前記第１の制御によって前記相対運動の速度を制御し、前記第２の領域では前記第２の制御によって前記相対運動の速度を制御することを特徴とする振動アクチュエータの駆動装置である。
【００１８】
請求項１６の発明は、請求項８から請求項１４のいずれか１項に記載の振動アクチュエータの駆動方法において、前記相対運動の速度を所望の速度に設定できる速度可変領域を設けるとともに、該速度可変領域を速度の高い側から第１の領域、第２の領域、第３の領域に分け、前記第１及び第３の領域では前記第１の制御によって前記相対運動の速度を制御し、前記第２の領域では前記第２の制御によって前記相対運動の速度を制御することを特徴とする振動アクチュエータの駆動方法である。
【００１９】
【発明の実施の形態】
以下、図面などを参照しながら、本発明の実施の形態をあげて、さらに詳しく説明する。
（第１実施形態）
図１は、第１実施形態に係る振動アクチュエータの駆動装置を示すブロック図、図２は、図１の駆動装置の動作を示すフローチャート、図３は、第１実施形態に係る駆動方法のうち、回転速度を増加させる場合を説明する図である。
第１実施形態の振動アクチュエータ１０は、第１圧電素子と第２圧電素子を弾性体に接合して成る振動子１１と、その振動子１１の方向に加圧されて接触し、その振動子１１に対して相対運動を行なう相対運動部材１２とを備え、超音波振動域を用いた超音波アクチュエータを用いることができる。
このタイプの振動アクチュエータ１０は、本出願人により、特開平８−１０３０８９号によって開示してあるので、詳しい説明は省略する。
【００２０】
また、駆動回路２０は、制御信号を生成する制御部２１と、制御部２１の制御信号に基づいて、所定電圧，所定周波数の交流電圧を発生する発振部２２と、発振部２２の出力の位相を９０度変化させる移相部２３と、移相部２３の信号を増幅して、第１駆動信号とする増幅部２４と、発振部２２の出力をそのまま増幅して、第２駆動信号とする増幅部２５と、第１駆動信号の電圧を検出して、制御部２１にフィードバックする検出部２６などとを備えている。
第１駆動信号は、前記第１圧電素子に印加される。これにより、振動子１１にはねじり振動が発生する。また、第２駆動信号は、前記第２圧電素子に印加され、これにより、振動子１１に縦振動が発生する。
【００２１】
次に、図２、図３を参照しながら、各制御ステップ毎に、本実施形態の動作を説明する。なお、図２は、図３は、振動アクチュエータを起動して、その回転数を増加させていく制御の工程を説明する図である。
ステップ１０１（Ｓ１０１）において、制御部２１は、図３の▲１▼に示すように、発振部２２から出力される第１駆動信号及び第２駆動信号の周波数（以下、駆動周波数ｆという）をｆ１、第１駆動信号の電圧値（捩じり振動電圧）をＶＴ１、第２駆動信号の電圧値（縦振動電圧）をＶＬ１に設定し、振動アクチュエータを起動させる。起動時に設定される駆動周波数（第１の設定値）ｆ１は、振動アクチュエータの共振周波数よりも高い周波領域となるように決められる。
【００２２】
Ｓ１０２では、制御部２１は、図３の▲２▼に示すように、駆動周波数ｆを、起動時の設定値ｆ１から予め設定された第２の設定値ｆ２に向けて減少させていく。このとき、第１駆動信号の電圧値は、起動時に設定された値（第１の設定値）ＶＴ１で一定に維持される。また、第２駆動信号の電圧値は、起動時に設定された値ＶＬ１で一定に維持される。Ｓ１０２では、駆動周波数ｆが減少していくにつれ、振動子１１に生じる振幅が増大する。そのため、相対運動部材１２の速度は上昇していく。
【００２３】
Ｓ１０３では、制御部２１は、駆動周波数ｆが第２の設定値ｆ２に達したか否かを判断する。そして、駆動周波数ｆがｆ２となったときは、駆動周波数ｆの変更を止める。
【００２４】
Ｓ１０４では、制御部２１は、図３の▲３▼に示すように、第１駆動信号の電圧値を、第１の設定値ＶＴ１から第２の設定値ＶＴ２に向けて増加させていく。このとき、第１駆動信号及び第２駆動信号の駆動周波数ｆは、第２の設定値ｆ２に維持される。また、第２駆動信号の電圧値も、起動時の設定値ＶＬ１に維持される。Ｓ１０４では、第１駆動信号の電圧値が上昇していくにつれ、ねじり振動の振幅が増大する。そのため、相対運動部材１２の速度は上昇していく。
【００２５】
Ｓ１０５では制御部２１は、第１駆動信号の電圧値が第２の設定値ＶＴ２に達したか否かを判断する。そして、電圧値がＶＴ２になったときは、第１駆動信号の電圧値の変更を止める。
【００２６】
Ｓ１０６では、制御部２１は、図３の▲４▼に示すように、駆動周波数ｆを、第２の設定値ｆ２から予め設定された第３の設定値ｆ３に向けて減少させていく。このとき、第１駆動信号の電圧値は、Ｓ１０５で設定された第２の設定値ＶＴ２で一定に維持される。また、第２駆動信号の電圧値は、起動時に設定された値ＶＬ１で一定に維持される。Ｓ１０６では、駆動周波数ｆが減少して前記共振周波数に近づいていくにつれ、振動子１１に生じる振幅が増大する。そのため、相対運動部材１２の速度は上昇していく。
【００２７】
Ｓ１０７では、制御部２１は、駆動周波数ｆが第３の設定値ｆ３に達したか否かを判断する。そして、駆動周波数ｆ３となったときは、駆動周波数ｆの変更を止める。
【００２８】
なお、相対運動部材１２の回転速度を減少させる場合には、前述したＳ１０１〜Ｓ１０７と逆の行程をたどるようにすればよい。
また、回転速度を増加又は減少させる場合に、目標速度に達したことを検出して、停止させるようにすればよい。
【００２９】
表１は、第１実施形態にかかる振動アクチュエータの駆動方法（表１Ａ）と、図７に示した従来の駆動方法（表１Ｂ、１Ｃ）との駆動結果を比較したものである。なお、ここでは、振動アクチュエータの回転速度を、最高速の状態から最低回転速度まで徐々に低下させていくように制御した駆動結果を比較した。
【００３０】
【表１】

【００３１】
表１から分かるように、（２）に示す周波数のみによる制御の場合には、最低回転速度９ｒｐｍである。また、（３）の捩じり振動電圧のみによる制御の場合には、最低回転速度３０ｒｐｍである。これらに対して、（１）の第１実施形態によれば、最低回転速度が０．８ｒｐｍとなり、ダイナミックレンジが広くなっている。
【００３２】
（第２実施形態）
図４は、第２実施形態に係る振動アクチュエータの駆動装置を示すブロック図、図５は、図４の駆動装置の動作を示すフローチャート、図６は、第２実施形態に係る駆動方法のうち、回転速度を増加させる場合を説明する図である。
なお、前述した第１実施形態と同様な機能を果たす部分には、同一の符号を付して、重複する説明は適宜省略する。
第２実施形態は、図４に示すように、相対運動部材１２の速度を検出する速度検出器２７を設けた点が第１実施形態と相違している。
【００３３】
ステップ２０１（Ｓ２０１）において、制御部２１は、図６の▲１▼に示すように、発振部２２から出力される第１駆動信号及び第２駆動信号の周波数（以下、駆動周波数ｆという）をｆ１、第１駆動信号の電圧値（捩じり振動電圧）をＶＴ１、第２駆動信号の電圧値（縦振動電圧）をＶＬ１に設定し、振動アクチュエータを起動させる。起動時に設定される駆動周波数（第１の設定値）ｆ１は、振動アクチュエータの共振周波数よりも高い周波数領域となるように決められる。
【００３４】
Ｓ２０２では、制御部２１は、図６の▲２▼に示すように、駆動周波数ｆを、起動時の設定値ｆ１から減少させていく。このとき、第１駆動信号の電圧値は、起動時に設定された値（第１の設定値）ＶＴ１で一定に維持される。また、第２駆動信号の電圧値は、起動時に設定された値ＶＬ１で一定に維持される。Ｓ２０２では、駆動周波数ｆが減少していくにつれ、振動子１１に生じる振幅が増大する。そのため、相対運動部材１２の速度は上昇していく。
【００３５】
Ｓ２０３では、制御部２１は、速度検出器２７によって相対運動部材１２の回転速度Ｎを計測する。
Ｓ２０４では、制御部２１は、前記回転速度Ｎが設定値Ｎ１であるか否かを判断する。そして、回転速度Ｎが設定値Ｎ１となったときは、駆動周波数ｆの変更を止める。
すなわち、Ｓ２０２からＳ２０４までは、第１駆動信号の電圧値及び第２駆動信号の電圧値は一定に維持されたまま、回転速度Ｎが予め設定された第１の設定値Ｎ１になるまで、駆動周波数ｆのみを変更する。
【００３６】
Ｓ２０５では、図６の▲３▼に示すように、第１駆動信号の電圧値を、第１の設定値ＶＴ１から増加させていく。このとき、第１駆動信号及び第２駆動信号の駆動周波数ｆは、回転速度Ｎが設定値Ｎ１となったときの駆動周波数（ｆ’とする）に維持される。また、第２駆動信号の電圧値も、起動時の設定値ＶＬ１に維持される。Ｓ２０５では、第１駆動信号の電圧値が上昇していくにつれ、ねじり振動の振幅が増大する。そのため、相対運動部材１２の速度は上昇していく。
【００３７】
Ｓ２０６では、制御部２１は、速度検出器２７によって相対運動部材１２の回転速度Ｎを計測する。
Ｓ２０７では、制御部２１は、前記回転速度Ｎが第２の設定値Ｎ２であるか否かを判断する。そして、回転速度Ｎが第２の設定値Ｎ２となったときは、第１駆動信号の電圧値の変更を止める。
【００３８】
Ｓ２０８では、制御部２１は、図６の▲４▼に示すように、駆動周波数ｆを、前記ｆ’から減少させていく。このとき、第１駆動信号の電圧値は、回転速度Ｎが第２の設定値Ｎ２となったときの電圧値（ＶＴ”とする）に維持される。また、第２駆動信号の電圧値は、起動時に設定された値ＶＬ１で一定に維持される。Ｓ２０８では、駆動周波数ｆが減少して前記共振周波数に近づいていくにつれ、振動子１１に生じる振幅が増大する。そのため、相対運動部材１２の速度は上昇していく。
Ｓ２０９では、制御部２１は、速度検出器２７によって相対運動部材１２の回転速度Ｎを計測する。
Ｓ２１０では、制御部２１は、前記回転速度Ｎが第３の設定値Ｎ３であるか否かを判断する。そして、回転速度Ｎが第３の設定値Ｎ３となったときは、駆動周波数ｆの変更を止める。図６では、このときの駆動周波数をｆ”で示す。
【００３９】
なお、相対運動部材１２の回転速度を減少させる場合には、前述したＳ２０１〜Ｓ２１０と逆の行程をたどるようにすればよい。
【００４０】
（変形形態）
以上説明した実施形態に限定されることなく、種々の変形や変更が可能であって、それらも本発明の均等の範囲内である。
例えば、駆動周波数ｆ１、縦振動電圧ＶＬ１、捩じり振動電圧ＶＴ１で起動し、まず、回転速度が設定値Ｎ１になるまで周波数ｆ１を減少（ｆ’）させ、その後に、第２実施形態と異なって、捩じり振動電圧ＶＴ１を設定値ＶＴ２まで増加させ、再び、回転速度が設定値Ｎ３になるまで周波数ｆ’を減少（ｆ”）させるようにしてもよい。なお、回転速度を減少させる場合には、逆行程を行なうようにすればよい。
【００４１】
また、前記各実施形態に加えて、回転数が低い場合には、縦振動電圧ＶＬを増加させ、回転数が高い場合には、縦振動電圧ＶＬを減少させるように制御を併用することも可能である。
【００４２】
【発明の効果】
以上詳しく説明したように、本発明によれば、相対運動部材の速度を変更するときに、まず、駆動信号の周波数のみを変更し、その後に、駆動信号の電圧値のみを変更し、再び、駆動信号の周波数のみを変更するようにしたので、２相のうち１相のみの電圧の変更ですみ、超低速駆動が可能となると共に、効率よく広いダイナミックレンジを実現することができる、という効果がある。
【図面の簡単な説明】
【図１】第１実施形態にかかる振動アクチュエータの駆動装置を示したブロック図である。
【図２】図１の駆動装置の動作を示すフローチャートである。
【図３】第１実施形態に係る駆動方法のうち、回転速度を増加させる場合を説明する図である。
【図４】第２実施形態にかかる振動アクチュエータの駆動装置を示したブロック図である。
【図５】図４の駆動装置の動作を示すフローチャートである。
【図６】第２実施形態にかかる駆動方法のうち、回転速度を増加させる場合を説明する図である。
【図７】従来の振動アクチュエータの駆動方法を示す線図である。
【符号の説明】
１０振動アクチュエータ
１１振動子
１２相対運動部材
２０駆動回路
２１制御部
２２発振部
２３移相部
２４，２５増幅部
２６検出部
２７速度検出器[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vibration actuator driving apparatus and driving method for controlling the speed of a vibration actuator by frequency and voltage.
[0002]
[Prior art]
FIG. 7 is a diagram showing a conventional method for driving a vibration actuator.
As shown in FIG. 7A, the conventional vibration actuator controls the rotational speed by changing only the driving frequency f. Further, as shown in FIG. 7B, the rotational speed is controlled by changing only the voltage value V. In this case, the two-phase voltage values were simultaneously changed at the same rate. In addition, these are sometimes controlled in combination.
[0003]
[Problems to be solved by the invention]
However, in the conventional driving method, the frequency of the driving signal is lowered when the speed is to be increased, but the speed does not increase when resonance is reached.
In order to increase the speed, it is necessary to increase the value of the applied voltage. In this case, since the voltage values of the two phases are simultaneously increased at the same rate, there is a problem that the input increases greatly. there were.
[0004]
On the other hand, when trying to reduce the speed, the frequency of the drive signal is increased. However, in the case of the different mode degenerative type vibration actuator, the vibration of the clutch component is also reduced. There was a problem that the operation became unstable and the rotation unevenness increased.
Further, even if the voltage values of the two phases are simultaneously lowered at the same rate, the same problem occurs because the vibration of the clutch component is similarly reduced.
[0005]
Therefore, in each of the above cases, it is difficult to drive at ultra-low speed. That is, it has been difficult to efficiently realize a wide dynamic range.
[0006]
An object of the present invention is to provide a driving device for a vibration actuator that can efficiently realize a wide dynamic range from ultra-low speed driving to high-speed driving.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention of claim 1 includes a first electromechanical transducer and a second electromechanical transducer, and the first electromechanical transducer and the second electromechanical transducer. A vibration actuator comprising: a vibrator that generates a driving force when a frequency voltage is supplied to the element; and a relative motion member that contacts the vibrator and performs a relative motion with the vibrator by the driving force; A drive circuit that supplies the frequency voltage to the first electromechanical conversion element and the second electromechanical conversion element; and the drive circuit includes the first electromechanical conversion element and the second electromechanical element. Without changing the voltage value of the frequency voltage supplied to the second electromechanical conversion element, the first control to change the frequency without changing the voltage value of the frequency voltage supplied to the conversion element, Said first electricity A second control for changing the voltage value of the frequency voltage supplied to械conversion element, by switching at least twice, to control the relative speed between the relative moving member and the vibrator, wherein the vibrator, The first electromechanical transducer causes vibration in a plane substantially parallel to the contact surface between the vibrator and the relative motion member, and intersects the contact surface by the second electromechanical transducer. A driving device for a vibration actuator, wherein the driving force is obtained by generating vibration in a direction .
[0008]
According to a third aspect of the present invention, in the vibration actuator driving device according to the first or second aspect, the first electromechanical transducer element is a first member that vibrates in a direction substantially parallel to the direction of the driving force. vibration is generated, and the second electromechanical conversion element, a driving apparatus of a vibration actuator, characterized in that for generating a second oscillation which oscillates in a direction intersecting the first direction of vibration of the vibrating is there.
According to a fourth aspect of the present invention, in the vibration actuator drive device according to any one of the first to third aspects, the drive circuit includes the first control, the second control, and the first control. The vibration actuator driving apparatus is characterized in that the relative speed between the vibrator and the relative motion member is controlled by performing each control in the order of the control.
[0009]
According to a fifth aspect of the present invention, in the vibration actuator drive device according to any one of the first to fourth aspects, the drive circuit is configured to switch from the first control to the second control. performed when the frequency of the frequency voltage has reached a predetermined value, said second control switch to the first control, the voltage value of the frequency voltage to be supplied to said first electromechanical transducer The vibration actuator driving device is characterized in that it is performed at the time when reaches a predetermined value.
[0010]
A sixth aspect of the present invention is the vibration actuator drive device according to any one of the first to fourth aspects, further comprising a speed detector that detects a speed of the relative motion member, wherein the drive circuit includes: Switching from the first control to the second control is performed when the speed of the relative motion member detected by the speed detector reaches a first value, and from the second control to the second control . The switching to the

control

1 is performed at the time when the speed of the relative motion member detected by the speed detector reaches a second value.
[0011]
According to a seventh aspect of the present invention, in the vibration actuator driving apparatus according to any one of the first to sixth aspects, the vibrator has a torsional vibration that vibrates in a plane substantially parallel to the contact surface. It raises a driving apparatus of a vibration actuator, characterized in that obtaining the driving force by generating a longitudinal vibration in a direction intersecting the front SL contact surface.
[0012]
According to an eighth aspect of the present invention, a driving force is generated in the vibrator by supplying a frequency voltage to the first electromechanical transducer and the second electromechanical transducer, and a gap between the vibrator and the vibrator is generated by the driving force. In the driving method of the vibration actuator for causing the relative motion member to perform relative motion, the respective voltage values of the frequency voltage supplied to the first electromechanical transducer and the second electromechanical transducer are not changed. The first control for changing the frequency and the voltage value of the frequency voltage supplied to the first electromechanical transducer without changing the voltage value of the frequency voltage supplied to the second electromechanical transducer. and a second control to change, by switching at least twice, to control the relative speed between the relative moving member and the vibrator, by the first electro-mechanical conversion element, said relative luck with the vibrator Vibration is generated in substantially parallel plane with the contact surface with the member, the year the second electro-mechanical conversion element, and characterized by obtaining the driving force by generating a vibration in a direction intersecting the contact surface This is a driving method of the vibration actuator.
[0013]
According to a tenth aspect of the present invention, in the method for driving a vibration actuator according to the eighth or ninth aspect, the first electromechanical transducer element is a first vibration that vibrates in a direction substantially parallel to the direction of the driving force. vibration is generated, and the second electromechanical conversion element, the driving method of a vibration actuator, characterized in that for generating a second oscillation which oscillates in a direction intersecting the first direction of vibration of the vibrating is there.
An eleventh aspect of the invention is the vibration actuator driving method according to any one of the eighth to tenth aspects, wherein the first control, the second control, and the first control are performed in this order. Thus, the vibration actuator driving method is characterized in that the relative speed between the vibrator and the relative motion member is controlled.
[0014]
The invention of claim 12 is the method of driving a vibration actuator according to any one of claims 11 claims 8, switching to the second control from the first control, the frequency voltage performed when the frequency reaches a predetermined value, switching to the first control from the second control, the value is a voltage value predetermined frequency voltage supplied to the first electromechanical transducer This is a method of driving a vibration actuator, which is performed at the time of reaching.
[0015]
A thirteenth aspect of the present invention is the vibration actuator driving method according to any one of the eighth to eleventh aspects, wherein the speed of the relative motion member is detected, and the second control is performed based on the first control. Switching to control is performed when the detected speed of the relative motion member reaches a first value, and switching from the second control to the first control is performed . This is a method of driving a vibration actuator, which is performed when the speed reaches the second value.
[0016]
The invention of claim 14, in has been the driving method of a vibration actuator according to claims 8 to any one of claims 13 to generate the torsional vibration vibrates in a plane substantially parallel to the contact surface, before Symbol A driving method of a vibration actuator, wherein the driving force is obtained by generating a longitudinal vibration that vibrates in a direction intersecting the contact surface.
[0017]
According to a fifteenth aspect of the present invention, in the vibration actuator drive device according to any one of the first to seventh aspects, the drive circuit is provided so that the speed of the relative motion can be set to a desired speed. The speed variable region is divided into a first region, a second region, and a third region from the higher speed side, and the speed of the relative motion is controlled by the first control in the first and third regions. In the second area, the speed of the relative motion is controlled by the second control .
[0018]
A sixteenth aspect of the present invention is the vibration actuator driving method according to any one of the eighth to fourteenth aspects, wherein a speed variable region in which the speed of the relative motion can be set to a desired speed is provided. The variable region is divided into a first region, a second region, and a third region from the higher speed side, and in the first and third regions, the speed of the relative motion is controlled by the first control, in the second region is a driving method of a vibration actuator and controlling the speed of said relative movement by said second control.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to the drawings.
(First embodiment)
FIG. 1 is a block diagram showing a driving device of the vibration actuator according to the first embodiment, FIG. 2 is a flowchart showing the operation of the driving device of FIG. 1, and FIG. 3 is a driving method according to the first embodiment. It is a figure explaining the case where a rotational speed is increased.
The vibration actuator 10 according to the first embodiment is in contact with a vibrator 11 formed by joining a first piezoelectric element and a second piezoelectric element to an elastic body, and is pressed in the direction of the vibrator 11 to contact the vibrator 11. And a relative motion member 12 that performs relative motion, and an ultrasonic actuator using an ultrasonic vibration region can be used.
This type of vibration actuator 10 has been disclosed in Japanese Patent Application Laid-Open No. 8-103089 by the applicant of the present invention, and a detailed description thereof will be omitted.
[0020]
In addition, the drive circuit 20 includes a control unit 21 that generates a control signal, an oscillation unit 22 that generates an AC voltage having a predetermined voltage and a predetermined frequency based on the control signal of the control unit 21, and a phase of the output of the oscillation unit 22 Phase shifter 23 that changes the phase difference by 90 degrees, the amplifier 24 that amplifies the signal of the phase shifter 23, and amplifies the output of the oscillating unit 22 as it is to obtain the second drive signal. An amplifying unit 25 and a detecting unit 26 that detects the voltage of the first drive signal and feeds back to the control unit 21 are provided.
The first drive signal is applied to the first piezoelectric element. Thereby, torsional vibration is generated in the vibrator 11. In addition, the second drive signal is applied to the second piezoelectric element, whereby longitudinal vibration is generated in the vibrator 11.
[0021]
Next, the operation of this embodiment will be described for each control step with reference to FIGS. 2 and 3. FIG. 2 is a diagram for explaining a control process in which FIG. 3 activates the vibration actuator and increases its rotational speed.
In step 101 (S101), the control unit 21 sets the frequencies of the first drive signal and the second drive signal output from the oscillating unit 22 (hereinafter referred to as drive frequency f) as shown in (1) of FIG. f1, the voltage value (torsional vibration voltage) of the first drive signal is set to VT1, the voltage value (longitudinal vibration voltage) of the second drive signal is set to VL1, and the vibration actuator is activated. The drive frequency (first set value) f1 set at the time of activation is determined so as to be in a frequency region higher than the resonance frequency of the vibration actuator.
[0022]
In S102, as shown in (2) in FIG. 3, the control unit 21 decreases the drive frequency f from the set value f1 at the time of startup toward the second set value f2 set in advance. At this time, the voltage value of the first drive signal is kept constant at a value (first set value) VT1 set at the time of startup. Further, the voltage value of the second drive signal is kept constant at the value VL1 set at the time of startup. In S102, the amplitude generated in the vibrator 11 increases as the drive frequency f decreases. Therefore, the speed of the relative motion member 12 increases.
[0023]
In S103, the control unit 21 determines whether or not the drive frequency f has reached the second set value f2. When the drive frequency f reaches f2, the change of the drive frequency f is stopped.
[0024]
In S104, the control unit 21 increases the voltage value of the first drive signal from the first set value VT1 toward the second set value VT2, as indicated by (3) in FIG. At this time, the drive frequency f of the first drive signal and the second drive signal is maintained at the second set value f2. Further, the voltage value of the second drive signal is also maintained at the set value VL1 at the time of activation. In S104, the amplitude of the torsional vibration increases as the voltage value of the first drive signal increases. Therefore, the speed of the relative motion member 12 increases.
[0025]
In S105, the control unit 21 determines whether or not the voltage value of the first drive signal has reached the second set value VT2. Then, when the voltage value becomes VT2, the change of the voltage value of the first drive signal is stopped.
[0026]
In S106, the control unit 21 decreases the drive frequency f from the second set value f2 toward the preset third set value f3 as indicated by (4) in FIG. At this time, the voltage value of the first drive signal is kept constant at the second set value VT2 set in S105. Further, the voltage value of the second drive signal is kept constant at the value VL1 set at the time of startup. In S106, the amplitude generated in the vibrator 11 increases as the drive frequency f decreases and approaches the resonance frequency. Therefore, the speed of the relative motion member 12 increases.
[0027]
In S107, the control unit 21 determines whether or not the drive frequency f has reached the third set value f3. When the driving frequency f3 is reached, the change of the driving frequency f is stopped.
[0028]
In order to decrease the rotational speed of the relative motion member 12, it is only necessary to follow the process reverse to S101 to S107 described above.
Further, when the rotational speed is increased or decreased, it is only necessary to detect that the target speed has been reached and stop the rotation.
[0029]
Table 1 compares the driving results of the vibration actuator driving method (Table 1A) according to the first embodiment and the conventional driving method (Tables 1B and 1C) shown in FIG. Here, a comparison was made between the results of driving in which the rotational speed of the vibration actuator was controlled to gradually decrease from the highest speed to the lowest speed.
[0030]
[Table 1]

[0031]
As can be seen from Table 1, in the case of control only by the frequency shown in (2), the minimum rotation speed is 9 rpm. In the case of control using only the torsional vibration voltage (3), the minimum rotation speed is 30 rpm. On the other hand, according to the first embodiment of (1), the minimum rotation speed is 0.8 rpm, and the dynamic range is widened.
[0032]
(Second Embodiment)
FIG. 4 is a block diagram showing a vibration actuator driving device according to the second embodiment, FIG. 5 is a flowchart showing the operation of the driving device of FIG. 4, and FIG. 6 is a driving method according to the second embodiment. It is a figure explaining the case where a rotational speed is increased.
In addition, the same code | symbol is attached | subjected to the part which fulfill | performs the same function as 1st Embodiment mentioned above, and the overlapping description is abbreviate | omitted suitably.
As shown in FIG. 4, the second embodiment is different from the first embodiment in that a speed detector 27 for detecting the speed of the relative motion member 12 is provided.
[0033]
In step 201 (S201), the control unit 21 sets the frequencies of the first drive signal and the second drive signal output from the oscillation unit 22 (hereinafter referred to as drive frequency f) as shown in (1) of FIG. f1, the voltage value (torsional vibration voltage) of the first drive signal is set to VT1, the voltage value (longitudinal vibration voltage) of the second drive signal is set to VL1, and the vibration actuator is activated. The drive frequency (first set value) f1 set at the time of activation is determined so as to be in a frequency region higher than the resonance frequency of the vibration actuator.
[0034]
In S202, the control unit 21 decreases the drive frequency f from the set value f1 at the start-up, as indicated by (2) in FIG. At this time, the voltage value of the first drive signal is kept constant at a value (first set value) VT1 set at the time of startup. Further, the voltage value of the second drive signal is kept constant at the value VL1 set at the time of startup. In S202, the amplitude generated in the vibrator 11 increases as the drive frequency f decreases. Therefore, the speed of the relative motion member 12 increases.
[0035]
In S <b> 203, the control unit 21 measures the rotational speed N of the relative motion member 12 by the speed detector 27.
In S204, the control unit 21 determines whether or not the rotational speed N is a set value N1. When the rotation speed N reaches the set value N1, the change of the drive frequency f is stopped.
That is, from S202 to S204, the voltage value of the first drive signal and the voltage value of the second drive signal are kept constant, and the driving is continued until the rotational speed N reaches the preset first set value N1. Only the frequency f is changed.
[0036]
In S205, as shown in (3) in FIG. 6, the voltage value of the first drive signal is increased from the first set value VT1. At this time, the drive frequency f of the first drive signal and the second drive signal is maintained at the drive frequency (referred to as f ′) when the rotation speed N becomes the set value N1. Further, the voltage value of the second drive signal is also maintained at the set value VL1 at the time of activation. In S205, the amplitude of the torsional vibration increases as the voltage value of the first drive signal increases. Therefore, the speed of the relative motion member 12 increases.
[0037]
In S <b> 206, the control unit 21 measures the rotational speed N of the relative motion member 12 by the speed detector 27.
In S207, the control unit 21 determines whether or not the rotational speed N is the second set value N2. When the rotation speed N reaches the second set value N2, the change of the voltage value of the first drive signal is stopped.
[0038]
In S208, the control unit 21 decreases the drive frequency f from f ′ as indicated by (4) in FIG. At this time, the voltage value of the first drive signal is maintained at a voltage value (referred to as VT ″) when the rotation speed N becomes the second set value N2. Further, the voltage value of the second drive signal is In step S208, as the drive frequency f decreases and approaches the resonance frequency, the amplitude generated in the vibrator 11 increases, so that the relative motion member 12 is maintained. The speed of will increase.
In S209, the control unit 21 measures the rotational speed N of the relative motion member 12 by the speed detector 27.
In S210, the control unit 21 determines whether or not the rotational speed N is the third set value N3. When the rotation speed N reaches the third set value N3, the change of the drive frequency f is stopped. In FIG. 6, the driving frequency at this time is indicated by f ″.
[0039]
In order to decrease the rotational speed of the relative motion member 12, it is only necessary to follow the process reverse to S201 to S210 described above.
[0040]
(Deformation)
The present invention is not limited to the embodiment described above, and various modifications and changes are possible, and these are also within the equivalent scope of the present invention.
For example, starting with the drive frequency f1, the longitudinal vibration voltage VL1, and the torsional vibration voltage VT1, first, the frequency f1 is decreased (f ′) until the rotational speed reaches the set value N1, and then the second embodiment and Differently, the torsional vibration voltage VT1 may be increased to the set value VT2, and the frequency f ′ may be decreased (f ″) until the rotational speed reaches the set value N3 again. In order to do so, a reverse stroke may be performed.
[0041]
In addition to the above-described embodiments, it is also possible to use control so as to increase the longitudinal vibration voltage VL when the rotational speed is low and to decrease the longitudinal vibration voltage VL when the rotational speed is high. It is.
[0042]
【The invention's effect】
As described above in detail, according to the present invention, when changing the speed of the relative motion member, first, only the frequency of the drive signal is changed, and then only the voltage value of the drive signal is changed, and again, Since only the frequency of the drive signal is changed, it is possible to change the voltage of only one of the two phases, enabling ultra-low speed drive and realizing a wide dynamic range efficiently. There is.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a drive device for a vibration actuator according to a first embodiment.
FIG. 2 is a flowchart showing the operation of the drive device of FIG.
FIG. 3 is a diagram illustrating a case where the rotational speed is increased in the driving method according to the first embodiment.
FIG. 4 is a block diagram showing a vibration actuator driving apparatus according to a second embodiment.
FIG. 5 is a flowchart showing the operation of the drive device of FIG. 4;
FIG. 6 is a diagram for explaining a case where the rotation speed is increased in the driving method according to the second embodiment.
FIG. 7 is a diagram showing a driving method of a conventional vibration actuator.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Vibration actuator 11 Vibrator 12 Relative motion member 20 Drive circuit 21 Control part 22 Oscillation part 23

Phase shift part

24, 25 Amplification part 26 Detection part 27 Speed detector

Claims

A first electromechanical conversion element and a second electromechanical conversion element are provided, and a driving force is generated by supplying a frequency voltage to the first electromechanical conversion element and the second electromechanical conversion element. A vibration actuator comprising: a vibrator that makes contact with the vibrator, and a relative motion member that makes a relative motion with the vibrator by the driving force;
A drive circuit for supplying the frequency voltage to the first electromechanical transducer and the second electromechanical transducer;
The drive circuit includes: a first control that changes a frequency without changing a voltage value of each of the frequency voltages supplied to the first electromechanical transducer and the second electromechanical transducer; And a second control for changing the voltage value of the frequency voltage supplied to the first electromechanical conversion element without changing the voltage value of the frequency voltage supplied to the second electromechanical conversion element. By switching, the relative speed between the vibrator and the relative motion member is controlled ,
The vibrator generates vibration in a plane substantially parallel to a contact surface between the vibrator and the relative motion member by the first electromechanical conversion element, and the second electromechanical conversion element A drive device for a vibration actuator, wherein the drive force is obtained by generating vibration in a direction intersecting the contact surface .

In the drive device of the vibration actuator according to claim 1,
The driving circuit drives the vibration actuator, wherein the frequency of the frequency voltage supplied to the first electromechanical transducer and the second electromechanical transducer is not changed during the second control. apparatus.

In the drive device of the vibration actuator according to claim 1 or 2,
The first electromechanical transducer generates a first vibration that vibrates in a direction substantially parallel to the direction of the driving force, and the second electromechanical transducer has a vibration direction of the first vibration. A drive device for a vibration actuator that generates a second vibration that vibrates in an intersecting direction.

In the drive device of the vibration actuator according to any one of claims 1 to 3,
The drive circuit controls a relative speed between the vibrator and the relative motion member by performing each control in the order of the first control, the second control, and the first control. Drive device for vibration actuator.

In the drive device of the vibration actuator according to any one of claims 1 to 4,
The drive circuit switches from the first control to the second control when the frequency of the frequency voltage reaches a predetermined value, and switches from the second control to the first control. Switching is performed when the voltage value of the frequency voltage supplied to the first electromechanical transducer element reaches a predetermined value.

In the drive device of the vibration actuator according to any one of claims 1 to 4,
A speed detector for detecting the speed of the relative motion member;
The drive circuit switches from the first control to the second control when the speed of the relative motion member detected by the speed detector reaches a first value, and the second control The switching from the control to the first control is performed when the speed of the relative motion member detected by the speed detector reaches a second value.

The drive device for the vibration actuator according to any one of claims 1 to 6,
The vibrator is vibrating, characterized in that obtaining the driving force by the contact surface and to generate torsional vibrations vibrates at substantially a plane parallel to generate longitudinal vibration in a direction intersecting the front SL contact surface Actuator drive.

A driving force is generated in the vibrator by supplying a frequency voltage to the first electromechanical transducer and the second electromechanical transducer, and a relative motion is caused between the vibrator and the relative motion member between the vibrator and the vibrator. In the driving method of the vibration actuator for performing
A first control for changing a frequency without changing a voltage value of each of the frequency voltages supplied to the first electromechanical transducer and the second electromechanical transducer; and the second electromechanical transducer. By switching at least twice the second control for changing the voltage value of the frequency voltage supplied to the first electromechanical transducer without changing the voltage value of the frequency voltage supplied to the element, Controlling the relative speed between the vibrator and the relative motion member ;
The first electromechanical transducer generates vibrations in a plane substantially parallel to the contact surface between the vibrator and the relative motion member, and intersects the contact surface by the second electromechanical transducer in the previous period. A driving method of a vibration actuator, wherein the driving force is obtained by generating vibration in a direction .

In the driving method of the vibration actuator according to claim 8,
A method of driving a vibration actuator, wherein the frequency of the frequency voltage supplied to the first electromechanical transducer and the second electromechanical transducer is not changed during the second control.

In the driving method of the vibration actuator according to claim 8 or 9,
The first electromechanical transducer generates a first vibration that vibrates in a direction substantially parallel to the direction of the driving force, and the second electromechanical transducer has a vibration direction of the first vibration. A driving method of a vibration actuator, wherein a second vibration that vibrates in an intersecting direction is generated.

In the driving method of the vibration actuator according to any one of claims 8 to 10,
A method of driving a vibration actuator, wherein a relative speed between the vibrator and the relative motion member is controlled by performing the first control, the second control, and the first control in this order.

In the driving method of the vibration actuator according to any one of claims 8 to 11,
Switching from the first control to the second control is performed when the frequency of the frequency voltage reaches a predetermined value,
The switching from the second control to the first control is performed when the voltage value of the frequency voltage supplied to the first electromechanical conversion element reaches a predetermined value. Driving method.

In the driving method of the vibration actuator according to any one of claims 8 to 11,
Detecting the speed of the relative motion member;
The switching from the first control to the second control is performed when the detected speed of the relative motion member reaches a first value,
The switching method from the second control to the first control is performed when the detected speed of the relative motion member reaches a second value.

In the driving method of the vibration actuator according to any one of claims 8 to 13,
It said contact surface and to generate torsional vibrations vibrates at substantially a plane parallel driving method for a vibration actuator, characterized in that obtaining the driving force by generating a longitudinal vibration that vibrates in a direction intersecting the contact surface .

In the drive device of the vibration actuator according to any one of claims 1 to 7,
The drive circuit divides a speed variable area provided so that the speed of the relative motion can be set to a desired speed into a first area, a second area, and a third area from the higher speed side,
In the first and third regions, the speed of the relative motion is controlled by the first control,
In the second area, the speed of the relative motion is controlled by the second control.

The driving method of the vibration actuator according to any one of claims 8 to 14,
While providing a speed variable area where the speed of the relative motion can be set to a desired speed, the speed variable area is divided into a first area, a second area, and a third area from the higher speed side,
In the first and third regions, the speed of the relative motion is controlled by the first control,
In the second region, the speed of the relative motion is controlled by the second control.