JP4265255B2 - Piezoelectric actuator driving device, driving method, timepiece, and electronic apparatus - Google Patents

Description

【００５５】
駆動制御手段２４０は、位相差検出手段２２０にて検出される位相差と基準位相差間の差が０近傍の値を示すように、駆動信号供給手段２１０から出力される駆動電圧信号ＳＤＲの駆動周波数を設計上の最適な駆動周波数ｆ０近傍にロックする駆動制御を実施する。また、この駆動制御手段２４０は、駆動制御が成功したか否かを判定し、駆動制御が失敗したと判定した場合に、比較電圧設定回路２３０に基準位相差の設定値を変更させる。この駆動制御手段２４０は、図１５に示すように、比較回路２４１と、積分回路２４２と、制御回路２４３とを備えている。
比較回路２４１は、比較電圧設定回路２３０から出力される比較電圧信号ＳＲＥＦの比較電圧値と、位相差検出手段２２０から出力される位相差信号ＳＰＤの電圧値とを比較して、積分回路２４２に比較情報を出力する。この比較回路２４１は、図１９に示すように、例えば、コンパレータ等から構成され、位相差信号ＳＰＤの電圧値が比較電圧信号ＳＲＥＦの比較電圧値以下である場合に、比較情報としてのハイレベルの信号ＳＣＴＨを積分回路２４２に出力する。また、位相差信号ＳＰＤの電圧値が比較電圧信号ＳＲＥＦの比較電圧値よりも大きい場合に比較情報としてのローレベルの信号ＳＣＴＬを積分回路２４２に出力する。
【００５６】
積分回路２４２は、比較回路２４１から出力される比較情報を積算し、積算情報を駆動信号供給手段２１０に出力し、駆動信号供給手段２１０から出力される駆動電圧信号ＳＤＲの駆動周波数を変更させる。また、積分回路２４２は、積算情報を適宜、比較電圧設定回路２３０に出力し、比較電圧設定回路２３０にて設定された基準位相差を変更させる。この積分回路２４２は、図１９に示すように、２つのＡＮＤゲート２４２Ａ１，２４２Ａ２と、アップダウンカウンタ２４２Ｂと、Ｄ／Ａコンバータ２４２Ｃとを備えている。
【００５７】
ＡＮＤゲート２４２Ａ１，２４２Ａ２は、比較回路２４１から出力されるハイレベルの信号ＳＣＴＨおよびローレベルの信号ＳＣＴＬと、後述する制御回路２４３のパルス発生源から出力されるパルス信号とを入力し、該パルス信号の入力タイミングに応じてアップダウンカウンタ２４２Ｂに信号を出力する。
具体的に、ＡＮＤゲート２４２Ａ１は、比較回路２４１から出力されるハイレベルの信号ＳＣＴＨを入力すると、パルス信号の入力タイミングに応じてアップダウンカウンタ２４２Ｂに信号を出力し、アップカウント入力を実施する。また、ＡＮＤゲート２４２Ａ２は、比較回路２４１から出力されるローレベルの信号ＳＣＴＨを入力すると、パルス信号の入力タイミングに応じてアップダウンカウンタ２４２Ｂに信号を出力し、ダウンカウント入力を実施する。
【００５８】
アップダウンカウンタ２４２Ｂは、ＡＮＤゲート２４２Ａ１，２４２Ａ２を介して入力される比較情報を積算する。このアップダウンカウンタ２４２Ｂは、例えば、１２ビットのカウンタ等から構成されており、ＡＮＤゲート２４２Ａ１，２４２Ａ２からの信号により、カウンタ値をアップあるいはダウンする。また、このアップダウンカウンタ２４２Ｂは、制御回路２４３からの信号をＲＥＳＥＴ入力端子に入力することにより、カウンタ値を０に設定するように構成されている。そして、このアップダウンカウンタ２４２Ｂは、ＡＮＤゲート２４２Ａ１，２４２Ａ２からの信号により、カウンタ値をアップあるいはダウンし、１２ビットのカウンタ値をＤ／Ａコンバータ２４２Ｃを出力する。また、このアップダウンカウンタ２４２Ｂは、カウンタ値をアップした結果、カウンタ値がＭＡＸを超え、キャリーが発生した場合、すなわち、駆動制御が失敗した場合に、カウンタ値を０にするとともに、比較電圧設定回路２３０のアップダウンカウンタ２３１にダウンカウント入力となる信号を出力する。
【００５９】
Ｄ／Ａコンバータ２４２Ｃは、内部にアップダウンカウンタ２４２Ｂのカウンタ値に応じた周波数制御電圧値が設定されている。そして、このＤ／Ａコンバータ２４２Ｃは、アップダウンカウンタ２４２Ｂから出力されるカウンタ値を入力すると、該カウンタ値に応じた周波数制御電圧値に相当する周波数制御電圧信号ＳＶＣを駆動信号供給手段２１０の可変周波数発振回路２１２に出力する。
なお、Ｄ／Ａコンバータ２４２Ｃにおける各カウンタ値および周波数制御電圧値は、駆動電圧信号ＳＤＲの駆動周波数に相当する。本実施形態において、これらカウンタ値、周波数制御電圧値、および駆動電圧信号ＳＤＲの駆動周波数は、以下の表２に示す関係を有している。
【００６０】
【表２】

【００６１】
制御回路２４３は、圧電アクチュエータＡの駆動開始から駆動終了までの間に、比較電圧設定回路２３０および積分回路２４２に適宜、制御指令信号を出力し、これら回路２３０，２４２を制御する。この制御回路２４３は、図１９に示すように、パルス発生源２４３Ａと、微分回路２４３Ｂ、計測手段としてのタイマ回路２４３Ｃとを備えている。
パルス発生源２４３Ａは、例えば、水晶振動子やセラミック振動子等の基準発振信号から所定の周波数のパルス信号ＣＬＫを出力する回路である。例えば、このパルス発生源２４３Ａは、積分回路２４２の２つのＡＮＤゲート２４２Ａ１，２４２Ａ２、およびタイマ回路２４３Ｃにパルス信号ＣＬＫを出力する。
【００６２】
微分回路２４３Ｂは、午前０時を示し、圧電アクチュエータＡの駆動を開始する旨のスタート信号、すなわち、日車５０（図１）の回転開始を示すスタート信号を入力すると、このスタート信号の入力タイミングに合わせてパルス信号ＳＴＡを出力する回路である。この微分回路２４３Ｂは、比較電圧設定回路２３０のアップダウンカウンタ２３１、積分回路２４２のアップダウンカウンタ２４２Ｂ、およびタイマ回路２４３Ｃにパルス信号ＳＴＡを出力する。
タイマ回路２４３Ｃは、圧電アクチュエータＡの駆動時間を計測する回路である。このタイマ回路２４３Ｃは、微分回路２４３Ｂから出力されるパルス信号ＳＴＡをトリガとして、パルス発生源２４３Ａから出力されるパルス信号ＣＬＫに基づいて、圧電アクチュエータＡの駆動時間を計測する。そして、このタイマ回路２４３Ｃは、計測した時間が所定時間経過すると、比較電圧設定回路２３０のアップダウンカウンタ２３１にアップカウント入力する信号ＴＩＭを出力する。
【００６３】
[５．圧電アクチュエータＡの駆動方法]
図２０は、圧電アクチュエータＡの駆動方法を説明するためのフローチャートである。図２１は、圧電アクチュエータＡの駆動方法を説明する図である。
以下では、駆動制御手段２４０が、位相差検出手段２２０にて検出される位相差と基準位相差間の差が０近傍の値を示すように、駆動信号供給手段２１０から出力される駆動電圧信号ＳＤＲの駆動周波数を設計上の最適な駆動周波数ｆ０近傍にロックする駆動制御を、２つに分けて説明する。
【００６４】
[５−１．設計上の周波数特性を有している場合の駆動方法]
先ず、位相差における周波数特性が設計上の特性を有している場合、例えば、図２１に示すように、加圧力が３ｇである場合（グラフＡ）には、以下に示す駆動制御が実施される。
駆動制御手段２４０の微分回路２４３Ｂは、スタート信号を入力すると、比較電圧設定回路２３０のアップダウンカウンタ２３１にパルス信号ＳＴＡを出力し、アップダウンカウンタ２３１のカウンタ値がＭＡＸ（７）に設定される（ステップＳ１：基準位相差設定工程）。すなわち、表１に示すように、基準位相差が９０°に設定され、比較電圧設定回路２３０は、位相差９０°に相当する比較電圧信号ＳＲＥＦを駆動制御手段２４０の比較回路２４１に出力する。
【００６５】
また、ステップＳ１と同時に、微分回路２４３Ｂは、積分回路２４２のアップダウンカウンタ２４２Ｂにパルス信号ＳＴＡを出力し、アップダウンカウンタ２３１のカウンタ値が０に設定される（ステップＳ２）。すなわち、表２に示すように、積分回路２４２から出力される周波数制御電圧値は０に設定され、駆動信号供給手段２１０から出力される駆動電圧信号ＳＤＲの駆動周波数が設定上の最小駆動周波数ｆｍｉｎ（２００ｋＨｚ）に設定される。
さらに、これらステップＳ１およびＳ２と同時に、微分回路２４３Ｂは、タイマ回路２４３Ｃにパルス信号ＳＴＡを出力し、タイマ回路２４３Ｃが圧電アクチュエータＡの駆動時間を計測する。
【００６６】
ステップＳ２の後、駆動信号供給手段２１０から所定の駆動周波数（ここでは、最小駆動周波数ｆｍｉｎ）の駆動周波数を有する駆動電圧信号ＳＤＲが圧電アクチュエータＡの振動体１０に印加され、振動体１０が振動する（ステップＳ３：駆動信号供給工程）。
この振動体１０の振動により、振動検出電極Ｔ１，Ｔ２から検出信号ＳＤ１およびＳＤ２が出力される。そして、位相差検出手段２２０は、これら検出信号ＳＤ１およびＳＤ２の位相差φを検出し、平均位相差に相当する電圧値Ｖφを有する位相差信号ＳＰＤを駆動制御手段２４０の比較回路２４１に出力する（ステップＳ４：位相差検出工程）。
【００６７】
そして、駆動制御手段２４０は、比較回路２４１において、比較電圧設定回路２３０から出力された比較電圧信号ＳＲＥＦの比較電圧値と、位相差検出手段２２０から出力された位相差信号ＳＰＤの電圧値とを比較する（ステップＳ５：位相差比較工程）。すなわち、比較回路２４１では、位相差検出手段２２０にて検出された位相差φが基準位相差である９０°以下であるか否かを判定している。ここで、図２１に示すように、ｆｍｉｎ（２００ｋＨｚ）の駆動周波数を有する駆動電圧信号ＳＤＲを振動体１０に印加した場合には、検出される位相差φは略０である。すなわち、ステップＳ３において、比較回路２４１は、位相差信号ＳＰＤの電圧値が比較電圧信号ＳＲＥＦの比較電圧値以下である（「Ｙｅｓ」）と判定し、駆動制御手段２４０の積分回路２４２に信号ＳＣＴＨを出力する。
【００６８】
積分回路２４２は、信号ＳＣＴＨを入力すると、ＡＮＤゲート２４２Ａ１を介してアップダウンカウンタ２４２Ｂがカウントアップし、カウンタ値を１上げる（ステップＳ６Ａ：積算情報算出工程）。
そして、ステップＳ６Ａにおいて、アップダウンカウンタ２４２Ｂのカウンタ値が１上がることで、積分回路２４２から出力される周波数制御電圧値が０から所定値に増加し、駆動信号供給手段２１０から出力される駆動電圧信号ＳＤＲの駆動周波数がｆｍｉｎ（２００ｋＨｚ）から増加する（ステップＳ７Ａ：周波数調整工程）。
【００６９】
ステップＳ６Ａにおいて、アップダウンカウンタ２４２Ｂがカウントアップすると、駆動制御手段２４０は、アップダウンカウンタ２４２Ｂのカウンタ値がＭＡＸの値（４０９５、表２参照）を超えたか否かを判定する（ステップＳ８：駆動制御判定工程）。すなわち、ここで、駆動制御手段２４０は、駆動制御が失敗したか否かを判定している。そして、ステップＳ８において、「Ｎｏ」と判定した場合には、再度、ステップＳ３に戻る。このように、ステップＳ５における判定が「Ｙｅｓ」であり、ステップＳ８における判定が「Ｎｏ」であれば、アップダウンカウンタ２４２Ｂのカウンタ値が増加し続ける。すなわち、駆動制御手段２４０は、設定上の最小駆動周波数ｆｍｉｎ（２００ｋＨｚ）〜アップダウンカウンタ２４２Ｂのカウンタ値のＭＡＸに相当する設定上の最大駆動周波数ｆｍａｘ（４００ｋＨｚ、表２参照）の範囲内で、駆動電圧信号ＳＤＲの駆動周波数を増加させる。
【００７０】
そして、ステップＳ３からＳ５、Ｓ６Ａ，Ｓ７Ａ，Ｓ８を繰り返し実施して、駆動電圧信号ＳＤＲの駆動周波数が増加することで、この駆動電圧信号ＳＤＲの駆動周波数が設計上の最適な駆動周波数ｆ０（３００ｋＨｚ）を超える。この際、ステップＳ５において、比較回路２４１は、位相差信号ＳＰＤの電圧値が比較電圧信号ＳＲＥＦの比較電圧値よりも大きい（「Ｎｏ」）と判定し、駆動制御手段２４０の積分回路２４２に信号ＳＣＴＬを出力する。
積分回路２４２は、信号ＳＣＴＬを入力すると、ＡＮＤゲート２４２Ａ２を介してアップダウンカウンタ２４２Ｂがカウントダウンし、カウンタ値を１下げる（ステップＳ６Ｂ：積算情報算出工程）。
【００７１】
そして、ステップＳ６Ｂにおいて、アップダウンカウンタ２４２Ｂのカウンタ値が１下がることで、積分回路２４２から出力される周波数制御電圧値が所定の値だけ減少し、駆動信号供給手段２１０から出力される駆動電圧信号ＳＤＲの駆動周波数が所定の値だけ減少する（ステップＳ７Ｂ：周波数調整工程）。
ステップＳ７Ｂの後、駆動制御手段２４０は、タイマ回路２４３Ｃにて計測した時間が所定時間経過しているか否かを判定する（ステップＳ９）。ここで、「Ｎｏ」と判定した場合には、再度、ステップＳ３に戻る。このように、位相差における周波数特性が設計上の特性を有している場合、例えば、加圧力が３ｇである場合には、ステップＳ３からステップＳ９が順次繰り返し実施されることで、位相差検出手段２２０にて検出された位相差φが、基準位相差である９０°に略等しくなり、駆動電圧信号ＳＤＲの駆動周波数が最適な駆動周波数ｆ０（３００ｋＨｚ）近傍にロックする。
なお、位相差比較工程Ｓ５、積算情報算出工程Ｓ６Ａ，Ｓ６Ｂ、周波数調整工程Ｓ７Ａ，Ｓ７Ｂが、本発明に係る駆動制御工程に相当する。
【００７２】
[５−２．設計上の周波数特性が変化している場合の駆動方法]
次に、位相差における周波数特性が設計上の特性から変化している場合、例えば、図２１に示すように、加圧力が通常の３ｇから５ｇとなっている場合（グラフＢ）には、以下に示す駆動制御が実施される。
ここで、図２１に示すように、グラフＢにおける位相差は、ステップＳ１において設定された基準位相差（９０°）よりも低い位置にある。このため、上述したステップＳ３からＳ５、Ｓ６Ａ，Ｓ７Ａ，Ｓ８を繰り返し実施して駆動電圧信号ＳＤＲの駆動周波数が設計上の最適な駆動周波数ｆ０（３００ｋＨｚ）を超えても、ステップＳ５において、比較回路２４１は、位相差信号ＳＰＤの電圧値が比較電圧信号ＳＲＥＦの比較電圧値よりも小さい（「Ｙｅｓ」）と判定する。
【００７３】
この結果、ステップＳ６Ａにおいて、アップダウンカウンタ２４２Ｂは、カウントアップを続け、カウンタ値がＭＡＸ（４０９５、表２参照）に到達する。すなわち、駆動電圧信号ＳＤＲの駆動周波数は、表２に示す設定上の最小駆動周波数ｆｍｉｎ（２００ｋＨｚ）から最大駆動周波数ｆｍａｘ（４００ｋＨｚ）まで増加される。
そして、駆動制御手段２４０は、ステップＳ８において、アップダウンカウンタ２４２Ｂがさらにカウントアップすることで、アップダウンカウンタ２４２Ｂのカウンタ値がＭＡＸの値を超えたと判定する（「Ｙｅｓ」）。すなわち、ここで、駆動制御手段２４０は、駆動制御が失敗したと判定している。
【００７４】
ステップＳ８において、アップダウンカウンタ２４２Ｂのカウンタ値がＭＡＸの値を超えると、アップダウンカウンタ２４２Ｂにキャリーが発生し、アップダウンカウンタ２４２Ｂのカウンタ値が０に切り替えられる（ステップＳ１０）。そして、ステップＳ２と同様に、積分回路２４２から出力される周波数制御電圧値は０に設定され、駆動信号供給手段２１０から出力される駆動電圧信号ＳＤＲの駆動周波数が設定上の最小駆動周波数ｆｍｉｎ（２００ｋＨｚ）に設定される。
また、ステップＳ１０と同時に、アップダウンカウンタ２４２Ｂは、比較電圧設定回路２３０のアップダウンカウンタ２３１にダウンカウント入力となる信号を出力し、アップダウンカウンタ２３１は、カウンタ値をＭＡＸの値から１減少させる（ステップＳ１１）。すなわち、アップダウンカウンタ２３１は、表１に示すように、カウンタ値をＭＡＸ（７）から６にカウントダウンし、基準位相差が９０°から１０°減少した８０°に設定される。そして、比較電圧設定回路２３０は、位相差８０°に相当する比較電圧信号ＳＲＥＦを駆動制御手段２４０の比較回路２４１に出力する。
【００７５】
ステップＳ１１の後、駆動制御手段２４０は、前述と略同様に、ステップＳ３からＳ５，Ｓ６Ａ，Ｓ７Ａ，Ｓ８を繰り返し実施する。すなわち、駆動制御手段２４０は、駆動電圧信号ＳＤＲの駆動周波数を設定上の最小駆動周波数ｆｍｉｎから最大駆動周波数ｆｍａｘまでの範囲で増加させ、位相差検出手段２２０にて検出された位相差φが基準位相差である８０°よりも大きくなる位置を見つけることを試みる。しかしながら、図２１に示すように、グラフＢにおける位相差は、ステップＳ１１において設定された基準位相差（８０°）よりも低い位置にある。このため、前述の基準位相差が９０°である場合と同様に、駆動電圧信号ＳＤＲの駆動周波数は、設定上の最大駆動周波数ｆｍａｘまで増加する。
以上のように、駆動制御手段２４０は、アップダウンカウンタ２３１のカウンタ値を１減少して基準位相差を１０°減らしながら、位相差検出手段２２０にて検出された位相差φが基準位相差よりも大きくなるまで、ステップＳ３〜Ｓ５，Ｓ６Ａ，Ｓ７Ａ，Ｓ８，Ｓ１０、Ｓ１１を順次実施する。本実施形態では、図１９に示すように、ステップＳ９において、アップダウンカウンタ２３１のカウンタ値が４になり、基準位相差を６０°に設定するまで、ステップＳ３〜Ｓ５，Ｓ６Ａ，Ｓ７Ａ，Ｓ８，Ｓ１０、Ｓ１１を順次実施する。
【００７６】
ステップＳ１１において、基準位相差が６０°に設定された後、ステップＳ３からＳ５，Ｓ６Ａ，Ｓ７Ａ，Ｓ８が繰り返し実施されることで、駆動電圧信号ＳＤＲの駆動周波数が設計上の最適な駆動周波数ｆ０（３００ｋＨｚ）を超える。そして、ステップＳ３において、位相差φが基準位相差６０°よりも大きい（「Ｎｏ」）と判定される。
この後、ステップＳ６Ｂに移行し、ステップＳ６Ｂにおいて、アップダウンカウンタ２４２Ｂがカウンタ値を１下げ、ステップＳ７Ｂにおいて、駆動電圧信号ＳＤＲの駆動周波数が所定の値だけ減少する。そして、駆動制御手段２４０は、ステップＳ９において、タイマ回路２４３Ｃにて計測した時間が所定時間経過しているか否かを判定し、「Ｎｏ」と判定した場合には、再度、ステップＳ３に戻り、駆動電圧信号ＳＤＲの駆動周波数を調整する。このように、位相差における周波数特性が設計上の特性から変化している場合、例えば、加圧力が３ｇから５ｇになっている場合には、ステップＳ３からステップＳ１１が繰り返し実施されることで、位相差検出手段２２０にて検出された位相差φが、基準位相差である例えば、６０°に略等しくなり、駆動電圧信号ＳＤＲの駆動周波数が最適な駆動周波数ｆ０（３００ｋＨｚ）近傍にロックする。
【００７７】
ここで、例えば、上述した基準位相差が６０°に設定され、この基準位相差（６０°）に基づいて駆動電圧信号ＳＤＲの駆動周波数がロックした後、位相差における周波数特性が設計上の特性に戻った場合には、図２１に示すｆ１近傍で駆動電圧信号ＳＤＲの駆動周波数がロックしていることになる。すなわち、駆動電圧信号ＳＤＲの駆動周波数が、最適な駆動周波数ｆ０（３００ｋＨｚ）とは異なる位置にロックしていることになる。
このため、駆動制御手段２４０は、ステップＳ９において、タイマ回路２４３Ｃにて計測した時間が所定時間経過しているか否かを判定する。そして、「Ｙｅｓ」と判定した場合には、タイマ回路２４３Ｃは、比較電圧設定回路２３０のアップダウンカウンタ２３１にアップカウント入力する信号ＴＩＭを出力する。
そして、アップダウンカウンタ２３１は、信号ＴＩＭを入力することにより、カウンタ値を１増加させる（ステップＳ１２）。すなわち、アップダウンカウンタ２３１は、カウンタ値を４から５にカウントアップし、基準位相差が６０°から１０°増加した７０°に設定される。そして、比較電圧設定回路２３０は、位相差７０°に相当する比較電圧信号ＳＲＥＦを駆動制御手段２４０の比較回路２４１に出力する。
【００７８】
ステップＳ１２の後、駆動制御手段２４０は、前述と略同様に、ステップＳ３からステップＳ１１を繰り返し実施する。この結果、駆動電圧信号ＳＤＲの駆動周波数は、位相差検出手段２２０にて検出された位相差φが基準位相差である７０°に略等しくなる駆動周波数ｆ２近傍（図２１）にロックする。このように、駆動制御手段２４０は、ステップＳ３からステップＳ１１を順次実施し、ステップＳ９における所定時間毎に、ステップＳ１２において、基準位相差を１０°増加させる。そして、駆動電圧信号ＳＤＲの駆動周波数は、図２１に示す駆動周波数ｆ１、ｆ２、ｆ３の順でロックする位置が変更され、最終的に最適な駆動周波数ｆ０（３００ｋＨｚ）近傍にロックする。
【００７９】
上述した駆動装置２００による制御にて、圧電アクチュエータＡが駆動されることにより、ロータ１００が回転し、これに伴って日回し中間車４０（図１）が回転する。そして、日回し中間車４０が回転する過程において、板バネ６４と接触子６５とが接触する。この接触状態を検出することで、日車５０が１歯分（１日分の日付範囲に相当する）だけ回動したことを検出し、駆動装置２００は、圧電アクチュエータＡの駆動を停止する。
【００８０】
[６．実施形態の効果]
上述した実施形態では、以下のような効果がある。
（１）駆動制御手段２４０は、比較回路２４１が比較電圧設定回路２３０から出力された比較電圧信号ＳＲＥＦの比較電圧値と、位相差検出手段２２０から出力された位相差信号ＳＰＤの電圧値とを比較して比較情報を算出し、積分回路２４２が比較情報を積算して積算情報を算出する。そして、この駆動制御手段２４０は、積算情報に基づいて駆動電圧信号ＳＤＲの駆動周波数を最小駆動周波数ｆｍｉｎから最大駆動周波数ｆｍａｘまで、順次増加させ、位相差φと基準位相差との差が０近傍の値を示すように、駆動電圧信号ＳＤＲの駆動周波数を最適な駆動周波数ｆ０近傍にロックする駆動制御を実施する。そしてまた、この駆動制御手段２４０は、積算情報に基づいて駆動制御が成功したか否かを判定する。このことにより、例えば、加圧力の変化により、位相差における周波数特性が変化した場合であっても、該変化を適切に認識できる。そして、駆動制御手段２４０は、駆動制御が失敗であると判定した場合に、比較電圧設定回路２３０に基準位相差の設定値を変更させ、この変更された基準位相差に基づく駆動制御を実施する。このことにより、適切な基準位相差に基づいて、駆動信号の駆動周波数の調整を実施できる。すなわち、位相差における周波数特性が変化した場合であっても、最適な駆動周波数ｆ０を有する駆動電圧信号ＳＤＲを圧電アクチュエータＡに印加できる。
【００８１】
（２）また、駆動制御手段２４０は、駆動信号供給手段２１０を制御する過程、すなわち、比較情報を積算してカウンタ値を算出する過程において、駆動制御が成功したか否かを判定するので、別途、例えば周波数カウンタ等の部材を不要とし、駆動装置２００の構成を簡素化できる。
【００８２】
（３）積分回路２４２は、ＡＮＤゲート２４２Ａ１，２４２Ａ２、アップダウンカウンタ２４２Ｂ、Ｄ／Ａコンバータ２４２Ｃを備えている。比較回路２４１は、比較電圧設定回路２３０から出力された比較電圧信号ＳＲＥＦの比較電圧値が位相差検出手段２２０から出力された位相差信号ＳＰＤの電圧値以下であるか否かにより、比較情報であるハイレベルの信号ＳＣＴＨおよびローレベルの信号ＳＣＴＬを出力する。そして、アップダウンカウンタ２４２Ｂは、信号ＳＣＴＨ，ＳＣＴＬに応じてカウントアップまたはカウントダウンし、信号ＳＣＴＨが継続して入力された結果、カウンタ値がＭＡＸの値を超え、キャリーが発生した場合に、比較電圧設定回路２３０に制御信号を出力する。この後、比較電圧設定回路２３０は、制御信号を入力することで、基準位相差の設定値を１０°減少させる。このことにより、駆動制御手段２４０は、位相差における周波数特性の変化を簡単な構成で容易に認識できるとともに、位相差における周波数特性の変化が自動的に判定されるので、変更された基準位相差に基づいて駆動制御を迅速に実施できる。
【００８３】
（４）比較電圧設定回路２３０は、アップダウンカウンタ２３１、およびＤ／Ａコンバータ２３２を備えている。そして、Ｄ／Ａコンバータ２３２には、アップダウンカウンタ２３１のカウンタ値に応じた比較電圧値が設定され、該比較電圧値が基準位相差に相当する。このことにより、駆動制御手段２４０から制御信号を入力することで、アップダウンカウンタ２３１はカウンタ値を切り換えることができ、基準位相差の設定および変更を容易に実施できる。また、回路構成が簡素化し、比較電圧設定回路２３０の制御を容易に実施できる。
【００８４】
（５）駆動制御手段２４０は、タイマ回路２４３Ｃを有し、このタイマ回路２４３Ｃは、圧電アクチュエータＡの駆動時間を計測する。そして、駆動制御手段２４０は、タイマ回路２４３Ｃの計測時間が所定時間経過した場合に、比較電圧設定回路２３０に基準位相差の設定値を１０°増加させ、この変更された基準位相差に基づく駆動制御を実施する。このことにより、駆動制御手段２４０による駆動制御が成功した後に、例えば、加圧力が５ｇから３ｇに戻る変化が生じ、位相差における周波数特性が変化した場合であっても、駆動電圧信号ＳＤＲの駆動周波数を最適な駆動周波数ｆ０近傍にロックできる。
【００８５】
（６）駆動制御手段２４０の微分回路２４３Ｂは、圧電アクチュエータＡの駆動開始を示すスタート信号を入力すると、比較電圧設定回路２３０のアップダウンカウンタ２３１にパルス信号ＳＴＡを出力する。そして、比較電圧設定回路２３０のアップダウンカウンタ２３１は、カウンタ値を０に設定し、基準位相差が初期値である９０°に設定される。このことにより、従前の駆動時に対して、位相差における周波数特性が変化した場合であっても、駆動電圧信号ＳＤＲの駆動周波数を常に最適な駆動周波数ｆ０に調整できる。
【００８６】
（７）時計は、圧電アクチュエータＡと、駆動装置２００とを具備し、駆動装置２００は、常に最適な駆動周波数ｆ０を有する駆動電圧信号ＳＤＲを圧電アクチュエータＡに印加する。このことにより、圧電アクチュエータＡは、所定の縦振動および屈曲振動で励振し、カレンダ表示機構を高効率で駆動させることができる。
【００８７】
[７．実施形態の変形]
尚、本発明は、前記実施形態に限定されるものではなく、以下に示すような変形をも含むものである。
例えば、前記実施形態では、駆動制御手段２４０は、比較回路２４１を有し、該比較回路２４１は、比較電圧設定回路２３０から出力された比較電圧信号ＳＲＥＦの比較電圧値と、位相差検出手段２２０から出力された位相差信号ＳＰＤの電圧値との間で大小を示す２値情報を出力していたが、これに限らない。例えば、比較電圧信号ＳＲＥＦの比較電圧値と位相差信号ＳＰＤの電圧値とを減算して絶対値情報を出力する構成であってもよい。ここで、駆動制御手段２４０は、絶対値情報を積算し、積算情報に基づいて駆動電圧信号ＳＤＲの駆動周波数を変更させる駆動制御を実施する。このような構成では、駆動制御手段２４０が、駆動電圧信号ＳＤＲの駆動周波数を、最小駆動周波数ｆｍｉｎから最大駆動周波数ｆｍａｘまで変更させる際に、例えば、比較電圧値に対して検出された位相差の電圧値との間で大幅な差がある場合に、駆動周波数を大きく変更することができ、駆動周波数を最適な駆動周波数ｆ０近傍に迅速にロックできる。
また、この際、駆動制御手段２４０の積分回路２４２としては、絶対値情報を平滑化するループフィルタを採用できる。
【００８８】
前記実施形態では、駆動制御手段２４０は、駆動制御を実施する際に、最小駆動周波数ｆｍｉｎから最大駆動周波数ｆｍａｘにかけて駆動電圧信号ＳＤＲの駆動周波数を増加させていたが、これに限らない。例えば、最大駆動周波数ｆｍａｘから最小駆動周波数ｆｍｉｎにかけて駆動電圧信号ＳＤＲの駆動周波数を減少させて駆動制御を実施する構成を採用してもよい。この際、駆動制御手段２４０のアップダウンカウンタ２４２Ｂは、継続してカウントダウンを実施し、カウンタ値が０になった場合に、制御信号を比較電圧設定回路２３０のアップダウンカウンタ２３１に出力する。すなわち、カウンタ値が０になった場合に、駆動制御が失敗であると判定する。そして、比較電圧設定回路２３０のアップダウンカウンタ２３１のカウンタ値が切り換えられ、基準位相差が変更される。
【００８９】
前記実施形態では、駆動制御手段２４０は、アップダウンカウンタ２４２Ｂのカウンタ値がＭＡＸを超え、キャリーが発生した場合に、制御信号を比較電圧設定回路２３０のアップダウンカウンタ２３１に出力する。すなわち、駆動制御手段２４０は、アップダウンカウンタ２４２Ｂにキャリーが発生した場合に、駆動制御が失敗したと判定し、基準位相差の設定値を１０°下げる。このような構成に限らず、アップダウンカウンタ２４２Ｂのカウンタ値が駆動信号供給手段２１０の可変周波数発振回路２１２の回路特性に応じた値になった場合に、駆動制御が失敗したと判定し、基準位相差の設定値を変更させる構成を採用してもよい。例えば、可変周波数発振回路２１２の発振周波数の温度特性として、±５０ｋＨｚの周波数変動幅を有する場合、駆動制御手段２４０は、アップダウンカウンタ２４２Ｂのカウンタ値が最適な駆動周波数ｆ０に対して＋５０ｋＨｚ（３５０ｋＨｚ）に相当する３０７２になったら、駆動制御が失敗したと判定する。そして、アップダウンカウンタ２４２Ｂのカウンタ値を最適な駆動周波数ｆ０に対して−５０ｋＨｚ（２５０ｋＨｚ）に相当する１０２４にセットするとともに、比較電圧設定回路２３０のアップダウンカウンタ２３１に制御信号を出力し、アップダウンカウンタ２３１のカウンタ値を１つ下げ、基準位相差の設定値を１０°下げる。このような構成では、駆動制御手段２４０は、最低限必要とされる範囲内（駆動周波数２５０ｋＨｚ〜３５０ｋＨｚ）で駆動電圧信号ＳＤＲの駆動周波数の調整を実施でき、駆動制御を迅速に実施できる。
【００９０】
前記実施形態では、駆動制御手段２４０は、圧電アクチュエータＡの駆動開始時に、比較電圧設定回路２３０に基準位相差の設定値を初期値（９０°）に変更させていたが、これに限らず、以下のような構成を採用してもよい。
例えば、駆動装置２００は、比較電圧設定回路２３０にて設定された基準位相差に関する基準位相差情報を記憶する記憶手段を具備する。そして、駆動制御手段２４０は、圧電アクチュエータＡの駆動を開始する際、記憶手段に記憶された従前の基準位相差情報に基づいて、比較電圧設定回路２３０に基準位相差の設定値を、例えば、従前の基準位相差、あるいは、従前の基準位相差よりも大きい値等に設定させる。このような構成では、従前の駆動時と略同じ状態で駆動制御を実施でき、従前の駆動時に対して位相差における周波数特性が変化していない場合に、迅速に駆動電圧信号ＳＤＲの駆動周波数を最適な駆動周波数ｆ０近傍にロックできる。
【００９１】
前記実施形態では、位相差検出手段２２０は、振動検出電極Ｔ１，Ｔ２から出力される検出信号ＳＤ１，ＳＤ２間の位相差を検出していたが、これに限らない。すなわち、位相差検出手段２２０は、駆動信号供給手段２１０から出力される駆動電圧信号ＳＤＲ、振動検出電極Ｔ１，Ｔ２から出力される検出信号ＳＤ１，ＳＤ２のいずれか２つの信号間の位相差を検出する構成としてもよい。
前記実施形態において、最適な駆動周波数を３００ｋＨｚとして説明したが、この値は、圧電アクチュエータＡの設計により適宜変更される。また、アップダウンカウンタ２４２Ｂのカウンタ値に応じた駆動周波数の調整幅、アップダウンカウンタ２３１のカウンタ値に応じた基準位相差の調整幅（１０°）は、その他の値に設定してもよい。
【００９２】
前記実施形態では、比較電圧設定回路２３０は、アップダウンカウンタ２３１と、Ｄ／Ａコンバータ２３２とを備えて構成されていたが、これに限らない。例えば、比較電圧設定回路２３０を、アップダウンカウンタ２３１と、複数の定電圧発生回路とで構成してもよい。例えば、アップダウンカウンタ２３１が、駆動制御手段２４０からの制御指令に応じてカウントアップまたはカウントダウンし、このカウンタ値に応じて複数の定電圧発生回路のうちのいずれかの定電圧発生回路が、それぞれ所定の電圧値に相当する比較電圧信号ＳＲＥＦを比較回路２４１に出力する。このことにより、カウンタ値、および駆動する定電圧発生回路の数を、基準位相差に対応させておくことで、基準位相差の設定および変更を容易に実施できる。また、定電圧発生回路を有する構成とすることで、基準位相差の変動を抑制できる。
【００９３】
前記実施形態では、圧電アクチュエータＡ、およびこの圧電アクチュエータＡを駆動する駆動装置２００を時計に具備した構成を説明したが、これに限らず、例えば、以下に示す非接触型ＩＣカードに具備した構成、その他の電子機器に具備した構成を採用してもよい。
図２２は、非接触型ＩＣカードの外観を示す斜視図である。図２３は、非接触型ＩＣカードの内部構成を示す図である。
非接触型ＩＣカード４００の表面側には、図２２に示すように、残金表示を実施する残金表示カウンタ４０１が設けられている。残金表示カウンタ４０１は、４桁の残金を表示するものであり、図２３に示すように、上位２桁を表示する表示部４０２と、下位２桁を表示する表示部４０３とを備えている。
【００９４】
図２４は、上位桁表示部４０２の構成を示す側面図である。
上位桁表示部４０２は、ロータ１００Ａを介して圧電アクチュエータＡ１に連結されており、ロータ１００Ａの駆動力によって駆動される。上位桁表示部４０２の主要部は、送り爪４０２Ａを有し、ロータ１００Ａが１／ｎ回転すると１回転する駆動ギア４０２Ａと、駆動ギア４０２Ａの１回転で１目盛分回転する第１上位桁表示車４０２Ｂと、第１上位桁表示車４０２Ｂの１回転で１目盛分回転する第２上位桁表示車４０２Ｃと、第１上位桁表示車４０２Ｂの非回転時に第１上位桁表示車４０２Ｂを固定する固定部材４０２Ｄとを備えている。なお、第２上位桁表示車４０２Ｂについても、第２上位桁表示車４０２Ｃを固定する図示しない固定部材が設けられている。
【００９５】
駆動ギア４０２Ａは、ロータ１００Ａが１／ｎ回転すると１回転する。そして、送り爪４０２Ａは、第１上位桁表示車４０２Ｂの送りギア部４０２Ｂ３に噛合しており、第１上位桁表示車４０２Ｂは１目盛分回転する。
なお、ロータ１００Ａを１／ｎ回転させるのは、動作の一例であり、これに限定するものではない。また、駆動ギア４０２Ａが１回転して、第１上位桁表示車４０２Ｂを１目盛分回転させるのも、動作の一例であり、これに限定するものではない。
【００９６】
さらに、第１上位桁表示車４０２Ｂが回転し、１回転すると、第１上位桁表示車４０２Ｂに設けられている送りピン４０２Ｂが送りギア４０２Ｂ２を回転させ、送りギア４０２Ｂが噛合している第２上位桁表示車４０２Ｃの送りギア４０２Ｃを回転させ、第２上位桁表示車４０２Ｃを１目盛分回転させる。
下位桁表示部４０３は、ロータ１００Ｂを介して圧電アクチュエータＡ２に連結されており、ロータ１００Ｂの駆動力によって駆動される。下位桁表示部４０３の主要部は、送り爪４０３Ａ１を有し、ロータ１００Ｂが１／ｎ回転すると１回転する駆動ギア４０３Ａと、駆動ギア４０３Ａの１回転で１目盛分回転する第１下位桁表示車４０３Ｂと、第１下位桁表示車４０３Ｂの１回転で１目盛分回転する第２下位表示車４０３Ｃとを備えている。
【００９７】
図２５は、下位桁表示部４０３の正面図である。図２６は、下位桁表示部４０３の側面図である。
第１下位桁表示車４０３Ｂは、駆動ギア４０３Ａの送り爪４０３Ａ１に噛合する送りギア部４０３Ｂ１を有しており、駆動ギア４０３Ａの１回転で１目盛分回転する。
そして、第１下位桁表示車４０３Ｂには、送りピン４０３Ｂ２が設けられており、第１下位桁表示車４０３Ｂが１回転する毎に、送りギア４０３Ｂ３を回転させ、第２下位桁表示車４０３Ｃを１目盛分回転させる。
この場合において、第１下位桁表示部４０３Ｂの固定部材４０３Ｄは、非回転時に送りギア部４０３Ｂ１に噛合して第１下位桁表示車４０３Ｂを固定する。また、第２下位桁表示車４０３Ｃの固定部材４０３Ｅは、第２下位桁表示車４０３Ｃの非回転時に送りギア部４０３Ｆに噛合して第２下位桁表示車４０３Ｃを固定する。
この場合において、アクチュエータＡ１およびアクチュエータＡ２は、駆動装置２００により同期して駆動されるように設定されており、駆動装置２００は、図示しないＩＣカードチップにより決済金額に相当する駆動制御信号が入力されることにより駆動されている。
【００９８】
前記実施形態において、図２０に示すフローを実施させる駆動制御手段２４０は、ロジック回路で構成する他、ＣＰＵ（Control Processing Unit）、メモリ等を配置してコンピュータとして機能できるように構成してもよい。この場合、このコンピュータに所定のプログラムを組み込んで、駆動制御手段２４０の機能を実現させるように構成する。
例えば、上記メモリに所定の制御プログラムをインターネット等の通信手段や、ＣＤ−ＲＯＭ、メモリカード等の記録媒体を介してインストールし、このインストールされたプログラムでＣＰＵ等を動作させて、駆動制御手段２４０の機能を実現させる。
なお、時計等の電子機器内に所定のプログラムをインストールするには、電子機器にメモリカードやＣＤ−ＲＯＭ等の記憶媒体を読み取る機器を外付けで電子機器に接続してもよい。さらには、ＬＡＮケーブル、電話線等を電子機器に接続して通信によってプログラムを供給しインストールしてもよいし、無線によってプログラムを供給してインストールしてもよい。
また、時計等の電子機器に構成されたメモリの中に予め、制御プログラムを組み込んでおき、ＣＰＵにより駆動制御手段２４０の機能を実現させるように構成してもよい。この場合、上記メモリに制御プログラムを、後からインストールしてもよく、そのインストールの仕方として、インターネットにより、又はＣＤ−ＲＯＭ、メモリカード等の記録媒体によって行ってもよい。
【発明の効果】
以上に述べたように、本発明によれば、種々の要因により位相差の周波数特性が変化した場合であっても、最適な駆動周波数を印加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】本実施形態における圧電アクチュエータが組み込まれた腕時計のカレンダ表示機構の構成を示す平面図。
【図２】前記実施形態における時計の断面図。
【図３】前記実施形態におけるカレンダ表示機構の詳細な構成を示す断面図。
【図４】前記実施形態における圧電アクチュエータの詳細な構成を示す平面図。
【図５】図４における圧電アクチュエータのＶ-Ｖ線断面図。
【図６】前記実施形態における振動体に設けられた駆動電極と振動検出電極の配置位置の一例を示す図。
【図７】前記実施形態における圧電素子の分極状態の一例を示す図。
【図８】前記実施形態における圧電素子の分極状態の一例を示す図。
【図９】前記実施形態における振動体に発生する屈曲振動を示す図。
【図１０】前記実施形態における振動体の振動による当接部の運動状態を示す図。
【図１１】前記実施形態における振動検出電極対の配置の変形例を示す図。
【図１２】前記実施形態における振動検出電極対の配置の変形例を示す図。
【図１３】前記実施形態における振動体の当接部が描く軌道を示した図。
【図１４】前記実施形態における振動体の縦振動および屈曲振動の位相差における周波数特性の変化の一例を示す図。
【図１５】前記実施形態における圧電アクチュエータの駆動装置の構成を示すブロック図。
【図１６】前記実施形態における位相差-ＤＣ変換回路の構成を示すブロック図。
【図１７】前記実施形態における位相差-ＤＣ変換回路において処理する波形を示す図。
【図１８】前記実施形態における位相差-ＤＣ変換回路において処理する波形を示す図。
【図１９】前記実施形態における比較電圧設定回路および駆動制御手段の構成を示す図。
【図２０】前記実施形態における圧電アクチュエータの駆動方法を説明するためのフローチャート。
【図２１】前記実施形態における圧電アクチュエータの駆動方法を説明する図。
【図２２】前記実施形態の変形例を示す図。
【図２３】前記実施形態の変形例を示す図。
【図２４】前記実施形態の変形例を示す図。
【図２５】前記実施形態の変形例を示す図。
【図２６】前記実施形態の変形例を示す図。
【符号の説明】
１０・・・振動体、３０，３１・・・圧電素子、２１０・・・駆動信号供給手段、２２０・・・位相差検出手段、２３０・・・比較電圧設定回路（基準位相差設定手段）、２３１・・・アップダウンカウンタ、２４０・・・駆動制御手段、２４２Ｂ・・・アップダウンカウンタ、２４３Ｃ・・・タイマ回路、Ａ・・・圧電アクチュエータ、Ｓ１・・・基準位相差設定工程、Ｓ３・・・駆動信号供給工程、Ｓ４・・・位相差検出工程、Ｓ５・・・位相差比較工程、Ｓ６Ａ，Ｓ６Ｂ・・・積算情報算出工程、Ｓ７Ａ，Ｓ７Ｂ・・・周波数調整工程、Ｓ８・・・駆動制御判定工程。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a driving device for a piezoelectric actuator including a vibrating body having a piezoelectric element, a driving method for a piezoelectric actuator, a timepiece, and an electronic device.
[0002]
[Background]
The piezoelectric element is excellent in conversion efficiency from electric energy to mechanical energy and responsiveness. For this reason, in recent years, various piezoelectric actuators utilizing the piezoelectric effect of piezoelectric elements have been developed.
This piezoelectric actuator has a vibrating body having a piezoelectric element as a main constituent element. For example, the vibrating body includes a plate-like reinforcing plate having a protruding portion that comes into contact with a driven body at one end, and the reinforcing member. There is a piezoelectric element attached to both surfaces of a plate, a driving electrode provided on the upper surface of the piezoelectric element, and a detection electrode that is electrically insulated from the driving electrode. Then, a predetermined alternating voltage is applied to the driving electrode of the vibrating body to excite the vibrating body by longitudinal vibration that expands and contracts in the longitudinal direction, and bending vibration that swings in a direction orthogonal to the longitudinal vibration direction is applied. A driving device for a piezoelectric actuator to be induced is known (see, for example, Patent Document 1).
[0003]
By such drive control by the driving device, the piezoelectric actuator rotates so that the protrusion of the vibrating body forms an elliptical orbit, and drives the driven body that comes into contact with the protrusion. Here, in order to drive the driven body with high efficiency, it is necessary to apply a predetermined longitudinal vibration and bending vibration by applying an AC voltage having an optimum driving frequency in design to the vibrating body of the piezoelectric actuator. . However, it is difficult to always apply an optimum driving frequency in design due to circuit characteristics of the driving device. For this reason, this driving device detects a detection signal from the detection electrode provided on the piezoelectric element, and performs feedback control for adjusting the driving frequency of the AC voltage applied to the driving electrode based on the detection signal. Yes.
[0004]
Specifically, the phase difference between the phase of the alternating voltage applied to the drive electrode and the phase of the detection signal detected from the detection electrode, or the phase difference between detection signals detected from the plurality of detection electrodes Is known to depend on the driving frequency of the AC voltage applied to the driving electrode. Therefore, in this drive device, the aforementioned phase difference corresponding to the optimum drive frequency in the design of the piezoelectric actuator is set in advance as a reference phase difference so that the detected phase difference approaches the preset reference phase difference. In addition, the drive frequency of the AC voltage applied to the drive electrode is adjusted. By performing such feedback control, it becomes possible to apply an AC voltage having an optimum driving frequency to the vibrating body of the piezoelectric actuator, and the piezoelectric actuator is excited by a predetermined longitudinal vibration and bending vibration, so that the driven body is driven. Can be driven with high efficiency.
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-291264 (FIG. 6)
[0006]
[Problems to be solved by the invention]
However, the driving is performed based on the phase difference between the phase of the AC voltage applied to the driving electrode and the phase of the detection signal detected from the detection electrode, or the phase difference between the detection signals detected from the plurality of detection electrodes. The characteristic with respect to the frequency changes depending on factors such as individual piezoelectric actuators, applied pressure, load, or temperature. Therefore, in the drive device as described above, the drive frequency is adjusted so that the detected phase difference approaches the preset reference phase difference. Therefore, if the frequency characteristics in the phase difference change due to the above factors, the piezoelectricity There is a problem that an optimum drive frequency cannot be applied to the vibration body of the actuator.
[0007]
In view of the above problems, an object of the present invention is to provide a piezoelectric actuator drive device that can apply an optimum drive frequency even when the frequency characteristics of the phase difference change due to various factors. Another object is to provide a piezoelectric actuator driving method, a timepiece, and an electronic device.
[0008]
[Means for Solving the Problems]
The drive device for a piezoelectric actuator of the present invention has a piezoelectric element, which vibrates in the first vibration mode when a drive signal having a predetermined drive frequency is given to the piezoelectric element and has a different vibration direction. A drive device for a piezoelectric actuator comprising a vibrating body that vibrates in a second vibration mode, the driving signal supplying means for supplying the driving signal to the vibrating body, the first vibration mode from the vibrating body, and / or Phase difference detecting means for detecting a detection signal representing vibration in the second vibration mode and detecting a phase difference between any two of the drive signal and the detection signal; and the drive signal and the detection A reference phase difference setting means for setting a reference phase difference as a reference between any two of the signals, and comparing the detected phase difference and the reference phase difference; The comparison information indicating the difference between the phase difference and the reference phase difference is calculated, and the comparison information is integrated to calculate integration information. Based on the integration information, the drive signal supply means is supplied with the drive frequency of the drive signal. Drive control means for performing drive control for changing the drive control means, wherein the drive control means determines whether the drive control is successful based on the integrated information, and determines that the drive control is unsuccessful. In this case, the reference phase difference setting unit is caused to change the set value of the reference phase difference, and the drive control based on the changed reference phase difference is performed.
Here, as the phase difference detected by the phase difference detection means, a phase difference between two detection signals representing vibrations in the first vibration mode and the second vibration mode can be employed. Further, the phase difference between the detection signal representing the vibration in the first vibration mode and the drive signal may be adopted, and the phase difference between the detection signal representing the vibration in the second vibration mode and the drive signal is adopted. May be.
Further, as the comparison information, binary information indicating the magnitude of the detected phase difference and the reference phase difference, absolute value information indicating the difference between the detected phase difference and the reference phase difference, or the like can be employed.
Furthermore, as the drive control means, a configuration including an up / down counter that counts binary information indicating magnitude, a configuration including a loop filter that smoothes comparison information, and the like can be employed.
[0009]
In the present invention, the drive control means calculates the comparison information by comparing the detected phase difference and the reference phase difference, and calculates the integration information by integrating the comparison information. Then, for example, the drive control unit changes the drive frequency of the drive signal to the drive signal supply unit based on the integration information so that the difference between the detected phase difference and the reference phase difference as the comparison information is within a predetermined range. Let Here, as a result of performing the drive control for changing the drive frequency of the drive signal, the drive control means determines whether or not the drive control is successful, for example, the difference between the detected phase difference and the reference phase difference as comparison information. It is determined whether it is within a predetermined range. Thereby, even if the frequency characteristic in the phase difference is changed, the change can be recognized. When the drive control unit determines that the drive control is unsuccessful, for example, when the difference between the detected phase difference and the reference phase difference, which is comparison information, does not fall within a predetermined range, The set value is changed, and drive control based on the changed reference phase difference is performed. Thus, the drive frequency of the drive signal can be adjusted using an appropriate reference phase difference. That is, even when the frequency characteristic in the phase difference changes, a drive signal having an optimum drive frequency can be applied to the piezoelectric actuator.
Here, in order to determine whether or not the drive control is successful, a configuration using a frequency counter or the like that detects the drive frequency of the drive signal output from the drive signal supply means is conceivable. In the present invention, it is possible to determine whether or not the drive control is successful in the process in which the drive control unit controls the drive signal supply unit, that is, in the process of calculating the integration information by integrating the comparison information. Therefore, a member such as a frequency counter is not required separately, and the configuration of the driving device can be simplified.
[0010]
In the piezoelectric actuator driving apparatus of the present invention, the drive control means includes an up / down counter, and the comparison information is information indicating a magnitude of the detected phase difference with respect to the reference phase difference, and the integration information Is a counter value calculated by the up / down counter counting up or down according to the comparison information.
In the present invention, the drive control means includes an up / down counter. For example, the comparison information is binary information indicating the magnitude of the detected phase difference with respect to the reference phase difference, and the up / down counter counts up or down according to the binary information. Then, the drive control means determines whether or not the drive control for changing the drive frequency of the drive signal is successful by recognizing that the up / down counter counts up or down and the counter value reaches a predetermined value. To do. In such a configuration, the drive control means can easily recognize a change in the frequency characteristic due to the phase difference with a simple configuration based on the counter value of the up / down counter. The drive control means can easily adjust the drive frequency of the drive signal based on the counter value of the uptown counter.
[0011]
In the piezoelectric actuator drive device of the present invention, it is preferable that the drive control means determines that the drive control has failed when a carry occurs as a result of the up / down counter calculating the counter value.
In the present invention, for example, when the drive control is performed, the drive control unit changes the drive frequency of the drive voltage from the set minimum drive frequency to the set maximum drive frequency. The drive control unit calculates binary information indicating the magnitude of the phase difference detected at the changed drive frequency with respect to the reference phase difference. The up / down counter counts up or down according to the binary information. Here, when the drive frequency of the drive voltage is changed until it exceeds the set maximum drive frequency, the up / down counter continues to count up according to the binary information, and the counter value is the value of MAX. And carry occurs. That is, even if the drive frequency of the drive voltage is changed to the maximum drive frequency on the setting, for example, the difference between the detected phase difference and the reference phase difference as comparison information does not fall within a predetermined range, and drive control has failed. judge. In conjunction with the occurrence of carry in the up / down counter, the up / down counter outputs a control signal to the reference phase difference setting means. The reference phase difference setting means changes the set value of the reference phase difference by inputting this control signal. In such a configuration, the drive control means automatically determines the change in the frequency characteristic in the phase difference without recognizing the counter value of the up / down counter, and quickly performs the drive control based on the changed reference phase difference. Can be implemented.
[0012]
In the piezoelectric actuator driving apparatus according to the present invention, the drive control means determines that the drive control is unsuccessful when the up / down counter calculates the counter value and the counter value becomes 0. It is preferable.
In the present invention, for example, when the drive control is performed, the drive control means changes the drive frequency of the drive voltage from the set maximum drive frequency to the set minimum drive frequency. The drive control unit calculates binary information indicating the magnitude of the phase difference detected at the changed drive frequency with respect to the reference phase difference. The up / down counter counts up or down according to the binary information. Here, when the drive frequency of the drive voltage is changed until it exceeds the set minimum drive frequency, the up / down counter continues to count down according to the binary information, and the counter value becomes zero. That is, even if the drive frequency of the drive voltage is changed to the minimum drive frequency on the setting, for example, the difference between the detected phase difference and the reference phase difference that are comparison information does not fall within a predetermined range, and drive control has failed. judge. When the counter value reaches 0, the up / down counter outputs a control signal to the reference phase difference setting means. The reference phase difference setting means changes the set value of the reference phase difference by inputting this control signal. In such a configuration, the drive control means automatically determines the change in the frequency characteristic in the phase difference without recognizing the counter value of the up / down counter, and quickly performs the drive control based on the changed reference phase difference. Can be implemented.
[0013]
In the piezoelectric actuator drive device of the present invention, the drive control means is configured such that when the up / down counter calculates the counter value, the drive control means has a predetermined counter value according to the characteristics of the drive signal supply means. It is preferable to determine that the drive control has failed.
Here, as the drive signal supply means, a drive circuit that applies the drive signal to the vibrating body, a predetermined frequency control voltage signal that is input to oscillate at a frequency according to the frequency control voltage signal, and the signal is sent to the drive circuit. It can be composed of a variable frequency oscillation circuit for outputting.
Incidentally, the oscillation frequency of the variable frequency oscillation circuit has a predetermined fluctuation range due to a disturbance such as temperature.
In the present invention, for example, the drive control means changes the drive frequency of the drive signal within a predetermined range centered on the optimum drive frequency. Even if the drive control unit changes the drive frequency, for example, the difference between the phase difference and the reference phase difference does not fall within a predetermined range, and the counter value of the up / down counter is a variable frequency that constitutes the drive signal supply unit. When the counter value corresponds to the fluctuation range of the oscillation frequency of the oscillation circuit, it is determined that the drive control has failed. In such a configuration, the drive control unit can adjust the drive frequency of the drive signal within the minimum required range corresponding to the frequency fluctuation range in the drive signal supply unit, and can quickly perform the drive control.
[0014]
In the piezoelectric actuator driving apparatus of the present invention, the reference phase difference setting means counts up or down in accordance with a control command from the drive control means to calculate a counter value, and according to the counter value And a D / A converter for setting the reference phase difference.
In the present invention, the reference phase difference setting means includes an up / down counter and a D / A converter. For example, the up / down counter counts up or down according to a control command from the drive control means, and the D / A converter outputs a voltage signal corresponding to a predetermined voltage value corresponding to the counter value of the up / down counter. Thus, setting and changing the reference phase difference can be easily performed by making the counter value and the voltage value set by the D / A converter correspond to the reference phase difference. Further, the circuit configuration is simplified and the control of the reference phase difference setting means can be easily performed.
[0015]
In the piezoelectric actuator driving apparatus of the present invention, the reference phase difference setting means counts up or down in accordance with a control command from the drive control means to calculate a counter value, and according to the counter value And a plurality of constant voltage generation circuits for setting the reference phase difference.
In the present invention, the reference phase difference setting means includes an up / down counter and a plurality of constant voltage generation circuits. For example, an up / down counter counts up or down in accordance with a control command from the drive control means, and one of the constant voltage generation circuits among the plurality of constant voltage generation circuits has a predetermined voltage according to the counter value. A voltage signal corresponding to the value is output. Thus, setting and changing the reference phase difference can be easily performed by making the counter value and the number of constant voltage generation circuits to be driven correspond to the reference phase difference. In addition, the configuration having the constant voltage generation circuit can suppress fluctuations in the reference phase difference.
[0016]
In the piezoelectric actuator driving apparatus of the present invention, the drive control means has a timer for measuring the elapsed driving time of the piezoelectric actuator, and when the time measured by the timer reaches a predetermined time, the reference It is preferable to cause the phase difference setting means to change the set value of the reference phase difference, and to perform the drive control based on the changed reference phase difference.
For example, when the drive control by the drive control means is successful and the drive signal supply means supplies a drive signal having a predetermined drive frequency to the vibrating body, the frequency characteristic in the phase difference changes again. The control means supplies the vibration body with a drive signal having a drive frequency different from the optimum drive frequency for the drive signal supply means.
In the present invention, the drive control means has a timer, and when the measured time of the timer reaches a predetermined time, the reference phase difference setting means changes the set value of the reference phase difference, and the changed reference position Drive control based on the phase difference is performed. As a result, after the drive control by the drive control means is successful, the drive frequency of the drive signal can be adjusted to the optimum drive frequency even when the frequency characteristic in the phase difference changes again.
[0017]
In the piezoelectric actuator driving apparatus of the present invention, it is preferable that the drive control means causes the reference phase difference setting means to set a reference phase difference setting value to an initial value when driving of the piezoelectric actuator is started.
According to the present invention, since the drive control means initializes the reference phase difference setting value to the reference phase difference setting means at the start of driving of the piezoelectric actuator, the frequency characteristic in the phase difference changes compared to the previous drive. Even in this case, the drive frequency of the drive signal can always be adjusted to the optimum drive frequency.
[0018]
The piezoelectric actuator driving apparatus of the present invention comprises storage means for storing reference phase difference information relating to the reference phase difference set by the reference phase difference setting means, and the drive control means drives the piezoelectric actuator. When starting, it is preferable that the phase difference setting unit sets the reference phase difference based on the previous reference phase difference information stored in the storage unit.
In the present invention, the drive device is configured to include storage means. Then, the drive control means sets the reference phase difference setting value to the phase difference setting means based on the previous reference phase difference information stored in the storage means at the start of driving of the piezoelectric actuator, for example, the previous reference phase difference. Or, it is set to a value larger than the previous reference phase difference. As a result, drive control can be performed in substantially the same state as in the previous drive, and the drive frequency of the drive signal can be quickly adjusted to the optimum drive frequency.
[0019]
The piezoelectric actuator driving method of the present invention includes a piezoelectric element, and when the piezoelectric element is given a drive signal having a predetermined driving frequency, the piezoelectric actuator vibrates in the first vibration mode and has a different vibration direction. A method for driving a piezoelectric actuator including a vibrating body that vibrates in a second vibration mode, the drive signal and a detection signal representing vibration in the first vibration mode and / or the second vibration mode. A reference phase difference setting step for setting a reference phase difference serving as a reference for a phase difference between any two of the signals, a drive signal supply step for supplying the drive signal to the vibrator, and a first step from the vibrator A detection signal representing vibration in one vibration mode and / or the second vibration mode is detected, and a phase difference between any two of the drive signal and the detection signal is detected. Comparing the detected phase difference and the reference phase difference to calculate comparison information indicating a difference between the phase difference and the reference phase difference, the calculated phase difference detection step A drive control step comprised of an integration information calculation step of integrating the comparison information to calculate integration information, a frequency adjustment step of changing the drive frequency of the drive signal based on the integration information, and based on the integration information A drive control determination step for determining whether or not the drive control step is successful, and a reference position set in the reference phase difference setting step when it is determined that the drive control determination step is unsuccessful The set value of the phase difference is changed, and the drive control process is executed based on the changed reference phase difference.
According to the present invention, the piezoelectric actuator driving method includes a reference phase difference setting step, a drive signal supply step, a phase difference detection step, a phase difference comparison step, an integrated information calculation step, and a frequency adjustment step. Since the drive control step and the drive control determination step are provided, the same operations and effects as those of the drive device described above can be enjoyed.
[0020]
The timepiece of the present invention has a piezoelectric element, and vibrates in the first vibration mode when a drive signal having a predetermined drive frequency is given to the piezoelectric element, and the second vibration having a different vibration direction from the first vibration mode. A piezoelectric actuator including a vibrating body that vibrates in a mode and the above-described driving device are provided.
In the present invention, the timepiece includes the piezoelectric actuator and the above-described driving device, and the above-described driving device always applies a driving signal having an optimal driving frequency to the piezoelectric actuator. As a result, the piezoelectric actuator is excited by predetermined longitudinal vibration and bending vibration, and for example, the calendar display mechanism in the timepiece can be driven with high efficiency to display the day, day of the week, month and the like.
[0021]
The electronic device of the present invention has a piezoelectric element, and when a drive signal having a predetermined drive frequency is given to the piezoelectric element, the electronic apparatus vibrates in the first vibration mode and has a second vibration direction different from that. A piezoelectric actuator including a vibrating body that vibrates in a vibration mode and the above-described driving device are provided.
According to the present invention, the electronic apparatus includes the piezoelectric actuator and the above-described driving device, and the above-described driving device always applies a driving signal having an optimal driving frequency to the piezoelectric actuator. As a result, the piezoelectric actuator can be excited by predetermined longitudinal vibration and bending vibration, and the driven body inside or outside the electronic apparatus can be driven with high efficiency.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[1. overall structure]
FIG. 1 is a plan view showing a configuration of a calendar display mechanism of a wristwatch in which the piezoelectric actuator A according to the present embodiment is incorporated.
As shown in FIG. 1, the main part of the calendar display mechanism includes a piezoelectric actuator A, a rotor 100 that is rotationally driven by the piezoelectric actuator A, a reduction wheel train that transmits the rotation of the rotor 100 while reducing the speed, and a reduction wheel. The date dial 50 is rotated roughly by the driving force transmitted through the row. The reduction gear train includes a date turning intermediate wheel 40 and a date turning wheel 60. The piezoelectric actuator A has a flat strip-shaped vibrating body 10, and the vibrating body 10 is disposed such that a tip end thereof is in contact with the outer peripheral surface of the rotor 100.
[0023]
FIG. 2 is a cross-sectional view of the timepiece shown in FIG.
In FIG. 2, a calendar display mechanism having a piezoelectric actuator A is incorporated in the mesh portion. A disk-shaped dial 70 is provided above the calendar display mechanism. A window portion 71 for displaying the date is provided on a part of the outer peripheral portion of the dial plate 70 so that the date of the date indicator 50 can be seen from the window portion 71. A movement 73 for driving the hands 72 and a drive circuit (not shown) are provided below the dial 70.
[0024]
FIG. 3 is a cross-sectional view showing a detailed configuration of the calendar display mechanism in FIG.
As shown in FIG. 3, the timepiece includes a ground plate 103 that is a first bottom plate, and a second bottom plate 104 that is arranged in a different manner from the ground plate 103. A shaft 101 for supporting the rotor 100 of the calendar display mechanism is erected on the main plate 103. The rotor 100 has a bearing (not shown) on its lower surface, and the tip of the shaft 101 is accommodated in the bearing. Therefore, the rotor 100 can rotate about the shaft 101 as a rotation axis. A gear 100 </ b> C that is coaxial with the rotor 100 and rotates together with the rotor 100 is provided on the top of the rotor 100.
[0025]
A shaft 41 for supporting the date driving intermediate wheel 40 is erected on the bottom plate 104. A bearing (not shown) is provided on the lower surface of the intermediate date driving wheel 40, and the tip portion of the shaft 41 is accommodated in the bearing. The date indicator driving intermediate wheel 40 includes a large diameter portion 4B and a small diameter portion 4A. The small-diameter portion 4A has a cylindrical shape slightly smaller in diameter than the large-diameter portion 4B, and a substantially square-shaped notch portion 4C is formed on the outer peripheral surface thereof. The small diameter portion 4A is fixed so as to be concentric with the large diameter portion 4B. A gear 100C at the top of the rotor 100 meshes with the large diameter portion 4B. Therefore, the date turning intermediate wheel 40 composed of the large diameter portion 4B and the small diameter portion 4A rotates in conjunction with the rotation of the rotor 100 and the shaft 41 as the rotation axis.
[0026]
As shown in FIG. 1, the date dial 50 has a ring shape, and an internal gear 5A is formed on the inner peripheral surface thereof. The date driving wheel 60 has a five-tooth gear and meshes with the internal gear 5A. As shown in FIG. 3, a shaft 61 is provided at the center of the date indicator driving wheel 60, and is loosely inserted into a through hole 62 formed in the bottom plate 104. The through hole 62 is formed long along the circumferential direction of the date dial 50. One end of the plate spring 63 is fixed to the bottom plate 104, and the other end presses the shaft 61 in the upper right direction in FIG. The leaf spring 63 biases the shaft 61 and the date driving wheel 60. The urging action of the leaf spring 63 prevents the date wheel 50 from swinging.
[0027]
One end of the leaf spring 64 is screwed to the bottom plate 104, and the other end is formed with a tip end portion 64A that is bent in a substantially V shape. Further, the contact 65 is arranged so as to come into contact with the leaf spring 64 when the date indicator driving intermediate wheel 40 rotates and the front end 64A enters the notch 4C. A predetermined voltage is applied to the leaf spring 64, and when the contact is made with the contact 65, the voltage is also applied to the contact 65. Therefore, the date feeding state can be detected by detecting the voltage of the contact 65. Note that a manually driven vehicle that meshes with the internal gear 5A may be provided, and the date indicator 50 may be driven when the user performs a predetermined operation on the crown (not shown).
[0028]
In the above configuration, the vibrating body 10 of the piezoelectric actuator A vibrates in a plane including the plate surface when a driving voltage is applied from the driving circuit. The outer surface of the rotor 100 is struck by vibration generated in the vibrating body 10 and is driven to rotate clockwise as indicated by an arrow in FIG. The rotation of the rotor 100 is transmitted to the date indicator driving wheel 60 via the date indicator driving intermediate wheel 40, and the date indicator driving wheel 60 rotates the date indicator 50 in the clockwise direction.
[0029]
Here, transmission of force from the vibrating body 10 to the rotor 100, transmission from the rotor 100 to the reduction wheel train, and transmission from the reduction wheel train to the date wheel 50 is transmission of force in a direction parallel to the plate surface of the vibration body 10. For this reason, it is possible to arrange the vibrating body 10 and the rotor 100 in the same plane and reduce the thickness of the calendar display mechanism, instead of stacking coils and rotors in the thickness direction as in a conventional step motor. Since the calendar display mechanism can be made thin, the thickness D of the mesh portion (FIG. 2) can be reduced to make the entire watch thin.
Further, according to the present embodiment, since the calendar display mechanism can be accommodated in the mesh portion (FIG. 2), the movement 73 can be made common between the timepiece having the calendar display mechanism and the timepiece having no calendar display mechanism. , Can increase productivity.
In recent years, various wristwatches having a power generation function have been proposed. In such wristwatches, at least two large components such as a power generation mechanism and a motor mechanism for driving a hand must be mounted. It is difficult to reduce the size. However, if the piezoelectric actuator A in the present embodiment is used instead of the motor, the hand movement driving mechanism can be made thinner and the entire timepiece can be made smaller.
[0030]
[2. Details of piezoelectric actuator]
FIG. 4 is a plan view showing a detailed configuration of the piezoelectric actuator A. FIG. FIG. 5 is a cross-sectional view of the piezoelectric actuator A taken along line VV.
As shown in FIG. 4, the vibrating body 10 is a rectangular plate surrounded by two long sides and two short sides. In addition, as shown in FIG. 5, the vibrating body 10 is substantially in the same shape as the piezoelectric elements 30, 31 between two rectangular and plate-shaped piezoelectric elements 30, 31. It has a laminated structure with a reinforcing plate 32 made of stainless steel or the like thinner than 31.
By disposing the reinforcing plate 32 between the piezoelectric elements 30 and 31 in this way, damage to the vibrating body 10 due to an external impact force due to overamplitude or dropping of the vibrating body 10 is reduced, and durability is improved. Can be improved. Further, by using a reinforcing plate 32 that is thinner than the piezoelectric elements 30 and 31, it is possible to prevent the vibration of the piezoelectric elements 30 and 31 as much as possible.
[0031]
Piezoelectric elements 30 and 31 include lead zirconate titanate (PZT (trademark)), crystal, lithium niobate, barium titanate, lead titanate, lead metaniobate, polyvinylidene fluoride, lead zinc niobate, scandium niobate Various things such as lead can be used.
As shown in FIG. 4, the vibrating body 10 has a contact portion 36 at one vertex where one long side and one short side intersect. The abutting portion 36 is obtained by a method such as cutting and forming the reinforcing plate 32 in FIG. 5, and the tip portion having a gently curved surface is projected from the piezoelectric elements 30 and 31. The vibrating body 10 abuts the tip of the abutting portion 36 on the outer peripheral surface of the rotor 100 and maintains a posture in which the long side forms an angle of about 135 degrees with the radius of the rotor 100. In order for the vibrating body 10 to maintain such a posture, the support member 11 and the spring member 300 are provided in the piezoelectric actuator A.
[0032]
In a preferred embodiment, the support member 11 is integrally formed with the reinforcing plate 32 by a method such as cutting and forming the reinforcing plate 32. As shown in the figure, the support member 11 is an L-shaped member, and a vertical portion that protrudes perpendicularly from the approximate center of one long side of the vibrating body 10 and a parallel to the long side from the tip of the vertical portion. It consists of the horizontal part extended toward the rotor 100 side. Here, the pin 39 which protruded from the ground plate 103 in FIG. 1 and FIG. 3 has penetrated the edge part 38 on the opposite side to a perpendicular | vertical part among the both ends of a horizontal part. The support member 11 and the vibrating body 10 fixed to the support member 11 can rotate about the pin 39 as a rotation axis.
[0033]
One end portion 300 </ b> A of the spring member 300 is engaged with a substantially central portion 11 </ b> A of the horizontal portion of the support member 11. In the spring member 300, a pin 300B protruding from the main plate 103 (FIGS. 1 and 3) passes through a substantially central portion thereof. The spring member 300 is rotatable about the pin 300B as a rotation axis. Further, the other end portion 300 </ b> C of the spring member 300 opposite to the end portion 300 </ b> A is engaged with the ground plate 103. In the present embodiment, the pressure for pressing the contact portion 36 against the outer peripheral surface of the rotor 100 is adjusted by changing the position of the end portion 300C.
[0034]
Specifically, if the end portion 300C is displaced clockwise around the pin 300B in FIG. 4, the force with which the one end portion 300A of the spring member 300 presses the portion 11A of the support member 11 upward increases. If the other end portion 300C is displaced counterclockwise, the pressing force is reduced. Here, when the force that presses the support member 11 upward increases, the force that the support member 11 tries to rotate counterclockwise in FIG. 4 around the pin 39 increases. Increases the force with which the rotor 100 is pressed. On the other hand, when the force that presses the support member 11 upward decreases, the force that the support member 11 tries to rotate clockwise decreases, so the force that the contact portion 36 presses the rotor 100 decreases. In this way, by adjusting the pressing force applied to the rotor 100 by the contact portion 36, the drive characteristics of the piezoelectric actuator A can be adjusted.
[0035]
In the present embodiment, the contact portion 36 pressed against the outer peripheral surface of the rotor 100 in this way has a curved shape. For this reason, even if the positional relationship between the rotor 100 and the vibrating body 10 varies due to dimensional variation or the like, the contact state between the outer peripheral surface of the rotor 100 that is a curved surface and the contact portion 36 that has a curved shape does not change much. . Therefore, the contact between the rotor 100 and the contact portion 36 can be maintained in a stable state. Further, in the present embodiment, it is only necessary to perform an operation such as polishing on the contact portion 36 that comes into contact with the rotor 100, so that the management of the contact portion with the rotor 100 is easy. As the contact portion 36, a conductor or a non-conductor can be used. However, if the contact portion 36 is formed from a non-conductor, the piezoelectric elements 30 and 31 are generally in contact with the rotor 100 formed of metal. Can be prevented from short-circuiting.
[0036]
[3. Configuration of electrodes provided on vibrating body]
FIG. 6 is a diagram illustrating an example of the arrangement positions of the drive electrodes and the vibration detection electrodes provided on the vibrating body 10.
In the example shown in FIG. 6, the rectangular vibration detection electrodes T <b> 1 and T <b> 2 are respectively disposed at two corner portions along one long side including the contact portion 36 on the surface of the piezoelectric element 30 having a rectangular shape. . Although illustration is omitted in FIG. 6, vibration detection electrodes T1 and T2 similar to these are arranged on the surface of the piezoelectric element 31 so as to oppose them. Here, the vibration detection electrode T1 disposed on the piezoelectric element 30 and the vibration detection electrode T1 disposed on the piezoelectric element 31 are connected, and a detection signal SD1 representing the vibration of the vibrating body 10 is obtained from this connection point. Similarly, the vibration detection electrode T2 disposed on the piezoelectric element 30 and the vibration detection electrode T2 disposed on the piezoelectric element 31 are connected, and a detection signal SD2 representing the vibration of the vibrating body 10 is obtained from this connection point. Here, there is a gap between the drive electrode 33 and the vibration detection electrodes T1 and T2, and both are electrically insulated. A similar drive electrode 33 is also provided on the surface of the piezoelectric element 31.
[0037]
7 and 8 are diagrams showing examples of the polarization states of the piezoelectric elements 30 and 31. FIG.
The piezoelectric elements 30 and 31 are polarized in the thickness direction as shown in FIGS. In the present embodiment, each of the piezoelectric elements 30 and 31 has a property of extending in the longitudinal direction when receiving an electric field in a direction corresponding to the polarization direction and contracting in the longitudinal direction when receiving an electric field in a direction opposite to the polarization direction. . Therefore, as shown in FIGS. 7 and 8, when the combinations of the polarization directions of the two piezoelectric elements are different, the driving method of each piezoelectric element is also different.
[0038]
In the example shown in FIG. 7, the piezoelectric elements 30 and 31 are polarized in opposite directions. In this case, as shown in FIG. 6, the reinforcing plate 32 is grounded, and the drive electrode 33 on the piezoelectric element 30 side and the drive electrode 33 on the piezoelectric element 31 side are connected, and between this connection point and the ground line. A drive voltage signal SDR as a drive signal having a predetermined drive frequency that alternately repeats the voltage + V and the voltage −V is applied. Here, when a voltage + V is applied between the connection point of the two drive electrodes 33 and the ground line, an electric field in the direction opposite to the polarization direction is applied to the piezoelectric elements 30 and 31, so The elements 30 and 31 contract in the longitudinal direction. On the other hand, when a voltage −V is applied between the two connection points and the ground line, an electric field in the same direction as each polarization direction is applied to the piezoelectric elements 30 and 31. 31 extends in the longitudinal direction. Because of this, when the driving voltage signal SDR having a predetermined driving frequency is given, the vibrating body 10 expands and contracts along its longitudinal direction. This stretching motion is called longitudinal vibration or vibration in the first vibration mode.
[0039]
In the example shown in FIG. 8, the piezoelectric elements 30 and 31 are polarized in the same direction. In this case, the reinforcing plate 32 is grounded, a voltage + V is applied between the drive electrode 33 on the piezoelectric element 30 side and the ground line, and a voltage −V is applied between the drive electrode 33 on the piezoelectric element 31 side and the ground line. A first phase is applied, and a voltage −V is applied between the drive electrode 33 on the piezoelectric element 30 side and the ground line, and a voltage + V is applied between the drive electrode 33 on the piezoelectric element 31 side and the ground line. Two phases are alternately repeated at a predetermined frequency. Here, in the first phase, an electric field in the direction opposite to the polarization direction is applied to the piezoelectric elements 30 and 31, so that the piezoelectric elements 30 and 31 contract in the longitudinal direction. In contrast, in the second phase, an electric field in the same direction as each polarization direction is applied to the piezoelectric elements 30 and 31, and thus the piezoelectric elements 30 and 31 extend in the longitudinal direction. Therefore, longitudinal vibration is generated in the vibrating body 10 by applying a driving voltage having such a predetermined frequency.
[0040]
By the way, it can be said that the vibrating body 10 is substantially line-symmetrical with a straight line passing through the center and facing the longitudinal direction as an axis of symmetry, but includes an asymmetric element such as the abutting portion 36. It is not a symmetrical shape. For this reason, when longitudinal vibration is generated in the vibrating body 10, a moment is generated that causes the vibrating body 10 to swing in a direction perpendicular to the longitudinal direction after the longitudinal vibration. Due to this moment, bending vibration is generated in the vibrating body 10.
[0041]
FIG. 9 is a diagram illustrating bending vibration generated in the vibrating body 10. FIG. 10 is a diagram illustrating a movement state of the contact portion 36 due to the vibration of the vibrating body 10.
As shown in FIG. 9, the bending vibration is a motion in which the vibrating body 10 swings in a direction orthogonal to the longitudinal direction in a plane including the plate surface of the vibrating body 10. When longitudinal vibration and bending vibration are generated in the vibrating body 10 in this way, the contact portion 36 at the tip of the vibrating body 10 moves while drawing an elliptical orbit as shown in FIG. The outer surface of the rotor 100 is struck by the abutting portion 36 that moves while drawing the elliptical orbit and is driven to rotate.
The amplitude of the longitudinal vibration and the amplitude of the bending vibration differ depending on the position on the plate surface of the vibrating body 10. There occurs a phenomenon that longitudinal vibration is remarkable at a certain position on the plate surface and bending vibration is remarkable at another position. The vibrating body 10 has resonance characteristics for longitudinal vibration and resonance characteristics for bending vibration. Here, the resonance characteristic for the longitudinal vibration and the resonance characteristic for the bending vibration of the vibrating body 10 are determined by the shape and material of the vibrating body 10, and the latter resonance frequency is slightly higher than the former resonance frequency.
[0042]
In the present embodiment, vibration detection electrode pairs T <b> 1 and T <b> 2 are disposed at two locations of the piezoelectric elements 30 and 31 in the vibrating body 10. Among these, the vibration detection electrode T <b> 1 is provided at a position where the vertical vibration is noticeable in the vibrating body 10. For this reason, the amplitude voltage of the detection signal obtained from the vibration detection electrode T <b> 1 becomes maximum in the vicinity of the resonance frequency related to the longitudinal vibration of the vibrating body 10. On the other hand, the vibration detection electrode T <b> 2 is provided at a position where the bending vibration appears remarkably in the vibrating body 10. For this reason, the amplitude voltage of the detection signal obtained from the vibration detection electrode T2 becomes maximum in the vicinity of the resonance frequency related to the bending vibration of the vibrating body 10.
Various arrangements of these vibration detection electrode pairs are possible in addition to those shown in FIG. FIG. 11 and FIG. 12 show such an example. In the example shown in FIG. 11, four vibration detection electrode pairs T <b> 1 to T <b> 4 are arranged at four corners of each surface of the piezoelectric elements 30 and 31 that form a rectangle. In the example shown in FIG. 12, two vibration detection electrode pairs T1 and T2 are formed at two corners along one short side including the contact portion 36 of each surface of the piezoelectric elements 30 and 31 having a rectangular shape. Each is arranged.
[0043]
[4. Configuration of Drive Device for Piezoelectric Actuator A]
First, before describing the configuration of the driving device 200, the relationship between the vibration state of the vibrating body 10 and the driving frequency of the applied drive voltage signal SDR and the level of longitudinal vibration and bending vibration generated in the vibrating body 10 are described. The frequency characteristics in the phase difference will be described in detail.
[0044]
FIG. 13 illustrates the trajectory drawn by the contact portion 36 of the vibrating body 10. The X axis and the Z axis in the figure will be described. As shown in FIG. 10, the Z axis is an axis in the longitudinal direction of the vibrating body 10, and the X axis is the Z axis in a plane including the plate surface of the vibrating body 10. It is an axis orthogonal to. In FIG. 13, Ra is the trajectory of the contact portion 36 when the drive frequency of the drive voltage signal SDR matches the resonance frequency of the longitudinal vibration, and Rd is the resonance frequency of the flexural vibration when the drive frequency of the drive voltage signal SDR is Represents the trajectory of the abutting portion 36. Rb and Rc represent the trajectory of the contact portion 36 when the drive frequency of the drive voltage signal SDR is an intermediate frequency between the resonance frequencies of longitudinal vibration and bending vibration.
[0045]
Since the bending vibration generated in the vibrating body 10 is caused by the longitudinal vibration, the phase of the bending vibration is delayed from the phase of the longitudinal vibration. The reason why the trajectory of the contact portion 36 is not a linear trajectory but an elliptical trajectory having a bulge as shown in FIG. 13 is that there is a phase difference between the longitudinal vibration and the bending vibration. The phase difference between the longitudinal vibration and the bending vibration depends on the driving frequency of the driving voltage vibration SDR. When the phase difference changes according to the driving frequency, it is considered that the shape of the elliptical orbit drawn by the contact portion 36 changes, and the rotational driving force applied to the rotor 100 changes.
Further, as shown in FIG. 13, as the drive frequency of the drive voltage signal SDR moves away from the resonance frequency of the longitudinal vibration and approaches the resonance frequency of the bending vibration, the major axis direction of the elliptical orbit gradually moves away from the Z axis, Tilt in a direction parallel to Thus, when the direction of the elliptical orbit of the contact portion 36 changes due to the change in the drive frequency of the drive voltage signal SDR, the magnitude of the rotational driving force applied to the rotor 100 is considered to change accordingly. In the present embodiment, due to the design of the piezoelectric actuator A, the optimum drive frequency of the drive voltage signal SDR that maximizes the magnitude of the rotational drive force applied to the rotor 100 by optimizing the shape of the elliptical orbit of the contact portion 36 is set. Set to 300 kHz.
[0046]
FIG. 14 is a diagram illustrating an example of a change in frequency characteristics in the phase difference between the longitudinal vibration and the bending vibration in the vibrating body 10.
As described above, the phase difference between the longitudinal vibration and the bending vibration in the vibrating body 10 depends on the drive frequency of the drive voltage signal SDR. Such frequency characteristics in the phase difference between the longitudinal vibration and the bending vibration vary depending on factors such as individual piezoelectric actuators, applied pressure, load, or temperature.
For example, the change of the frequency characteristic of the phase difference due to the change of the applied pressure is shown in FIG. Specifically, the graph A shown in FIG. 14 shows the frequency characteristics of the phase difference when the applied pressure is 3 g, and the graph B shows the frequency characteristics of the phase difference when the applied pressure is 5 g. As shown in FIG. 14, the phase difference between the longitudinal vibration and the bending vibration changes due to increase / decrease in the applied pressure, and when the applied pressure increases, the phase difference tends to hardly occur.
[0047]
FIG. 15 is a block diagram showing the configuration of the driving device 200 for the piezoelectric actuator A in the present embodiment.
The driving device 200 is designed in view of the characteristics of the vibrating body 10 and the characteristics of the circuits constituting the driving device 200 described above. That is, in order to suppress the frequency fluctuation of the driving voltage signal SDR according to the circuit characteristics, the driving device 200 detects the phase difference between the longitudinal vibration and the bending vibration generated in the vibrating body 10 (detected from the vibration detection electrodes T1 and T2). The drive frequency is controlled so that the phase difference between the detected signals is equal to the reference phase difference corresponding to the optimum drive frequency f0 (300 kHz) of the drive voltage signal SDR. The driving device 200 also controls the reference phase difference in response to a change in frequency characteristics in the phase difference between the longitudinal vibration and the bending vibration generated in the vibrating body 10. As shown in FIG. 15, the driving device 200 includes a driving signal supply unit 210, a phase difference detection unit 220, a comparison voltage setting circuit 230 as a reference phase difference setting unit, and a drive control unit 240. .
[0048]
The drive signal supply unit 210 applies a drive voltage signal SDR having a predetermined drive frequency to the drive electrode 33 of the vibrating body 10 under the control of the drive control unit 240. As shown in FIG. 15, the drive signal supply unit 210 includes a drive circuit 211 and a variable frequency oscillation circuit 212.
The drive circuit 211 is electrically connected to the drive electrode 33 of the vibrator 10, amplifies the output signal Sdr output from the variable frequency oscillator circuit 212, and applies the drive voltage signal SDR to the drive electrode 33 of the vibrator 10. Circuit.
The variable frequency oscillation circuit 212 is a circuit that oscillates at a frequency corresponding to the frequency control voltage signal SVC output from the drive control means 240 and outputs the signal Sdr to the drive circuit 211. In the present embodiment, it is assumed that the oscillation frequency of the variable frequency oscillation circuit 212 has a predetermined frequency fluctuation range depending on, for example, temperature.
[0049]
The phase difference detection unit 220 detects detection signals output from the vibration detection electrodes T1 and T2 due to vibration of the vibration body 10 as a result of the drive signal supply means 210 applying the drive voltage signal SDR to the drive electrode 33 of the vibration body 10. Then, the phase difference between these detection signals is detected. As shown in FIG. 15, the phase difference detection unit 220 includes a waveform shaping circuit 221 and a phase difference-DC conversion circuit 222.
The waveform shaping circuit 221 is electrically connected to the vibration detection electrodes T1 and T2 of the vibrating body 10, and receives the detection signals SD1 and SD2 output from the vibration detection electrodes T1 and T2, and the waveforms of these detection signals SD1 and SD2 , And outputs the shaped detection signals SD1 and SD2 to the phase difference-DC conversion circuit 222.
[0050]
FIG. 16 is a block diagram showing a configuration of the phase difference-DC conversion circuit 222.
The phase difference-DC conversion circuit 222 is a circuit that outputs a signal corresponding to the phase difference between the detection signals SD1 and SD2 shaped by the waveform shaping circuit 221. As illustrated in FIG. 16, the phase difference-DC conversion circuit 222 includes a phase difference detection unit 222A and an average voltage conversion unit 222B.
[0051]
17 and 18 are diagrams showing waveforms processed in the phase difference-DC conversion circuit 222. FIG.
As shown in FIGS. 17 and 18, the phase difference detector 222A generates a phase difference signal SDD having a pulse width corresponding to the phase difference between the detection signals SD1 and SD2, and the phase difference signal SDD is converted into an average voltage converter 222B. Output to.
As shown in FIGS. 17 and 18, the average voltage converter 222B averages the phase difference signal SDD output from the phase difference detector 222A, and a phase difference signal having a level proportional to the phase difference between the detection signals SD1 and SD2. The SPD is output to the drive control means 240.
In the example shown in FIG. 17, the phase difference between the detection signals SD1 and SD2 is small. Therefore, a phase difference signal SDD having a small pulse width Δθ1 is output, and a phase difference signal SPD having a small voltage value Vav1 is output. On the other hand, in the example shown in FIG. 18, the phase difference between the detection signals SD1 and SD2 is large. Therefore, a phase difference signal SDD having a large pulse width Δθ2 is output, and a phase difference signal SPD having a large voltage value Vav2 is output.
[0052]
FIG. 19 is a diagram showing the configuration of the comparison voltage setting circuit 230 and the drive control means 240.
The comparison voltage setting circuit 230 is a circuit that outputs a comparison voltage signal corresponding to a predetermined reference phase difference to the drive control unit 240 under the control of the drive control unit 240. The comparison voltage setting circuit 230 includes an up / down counter 231 and a D / A converter 232 as shown in FIG.
The up / down counter 231 receives an up count input or a down count input according to a signal appropriately output from the drive control means 240, and increases or decreases the counter value when each of these up / down count inputs is received. Is configured to do. Further, the up / down counter 231 is configured to set a counter value to a predetermined value, for example, a MAX counter value, by inputting a control signal output from the drive control means 240 when driving of the piezoelectric actuator A is started. Has been. The up / down counter 231 is composed of a 3-bit counter, for example, and outputs a 3-bit counter value based on up-counting or down-counting to the D / A converter 232.
[0053]
The D / A converter 232 is internally set with a comparison voltage value corresponding to the counter value of the up / down counter 231. When the D / A converter 232 receives the counter value output from the up / down counter 231, the D / A converter 232 outputs a comparison voltage signal SREF corresponding to a comparison voltage value corresponding to the counter value to the drive control unit 240.
Note that each counter value and comparison voltage value in the D / A converter 232 corresponds to a predetermined reference phase difference. In the present embodiment, the counter value, the reference phase difference, and the comparison voltage value have the relationship shown in Table 1 below.
[0054]
[Table 1]

[0055]
The drive control unit 240 drives the drive voltage signal SDR output from the drive signal supply unit 210 so that the difference between the phase difference detected by the phase difference detection unit 220 and the reference phase difference indicates a value near zero. Drive control is performed to lock the frequency in the vicinity of the optimum drive frequency f0 in design. Further, the drive control means 240 determines whether or not the drive control is successful, and when it is determined that the drive control has failed, causes the comparison voltage setting circuit 230 to change the set value of the reference phase difference. As shown in FIG. 15, the drive control unit 240 includes a comparison circuit 241, an integration circuit 242, and a control circuit 243.
The comparison circuit 241 compares the comparison voltage value of the comparison voltage signal SREF output from the comparison voltage setting circuit 230 with the voltage value of the phase difference signal SPD output from the phase difference detection means 220, and sends it to the integration circuit 242. Output comparison information. As shown in FIG. 19, the comparison circuit 241 is composed of, for example, a comparator. When the voltage value of the phase difference signal SPD is equal to or lower than the comparison voltage value of the comparison voltage signal SREF, the comparison circuit 241 has a high level as comparison information. The signal SCTH is output to the integrating circuit 242. Further, when the voltage value of the phase difference signal SPD is larger than the comparison voltage value of the comparison voltage signal SREF, a low level signal SCTL is output to the integration circuit 242 as comparison information.
[0056]
The integration circuit 242 integrates the comparison information output from the comparison circuit 241, outputs the integration information to the drive signal supply unit 210, and changes the drive frequency of the drive voltage signal SDR output from the drive signal supply unit 210. Further, the integration circuit 242 appropriately outputs integration information to the comparison voltage setting circuit 230, and changes the reference phase difference set by the comparison voltage setting circuit 230. As shown in FIG. 19, the integration circuit 242 includes two AND gates 242A1 and 242A2, an up / down counter 242B, and a D / A converter 242C.
[0057]
The AND gates 242A1 and 242A2 receive the high-level signal SCTH and the low-level signal SCTL output from the comparison circuit 241 and a pulse signal output from a pulse generation source of the control circuit 243 described later. A signal is output to the up / down counter 242B in accordance with the input timing.
Specifically, when the high level signal SCTH output from the comparison circuit 241 is input, the AND gate 242A1 outputs a signal to the up / down counter 242B in accordance with the input timing of the pulse signal, and performs the up count input. When the AND gate 242A2 receives the low-level signal SCTH output from the comparison circuit 241, the AND gate 242A2 outputs a signal to the up / down counter 242B in accordance with the input timing of the pulse signal, and performs the down count input.
[0058]
The up / down counter 242B integrates comparison information input via the AND gates 242A1 and 242A2. The up / down counter 242B is composed of, for example, a 12-bit counter or the like, and increases or decreases the counter value by signals from the AND gates 242A1 and 242A2. The up / down counter 242B is configured to set the counter value to 0 by inputting a signal from the control circuit 243 to the RESET input terminal. The up / down counter 242B increases or decreases the counter value according to signals from the AND gates 242A1 and 242A2, and outputs the 12-bit counter value to the D / A converter 242C. Further, the up / down counter 242B sets the counter value to 0 and sets the comparison voltage when the counter value exceeds MAX and the carry occurs, that is, when the drive control fails as a result of increasing the counter value. A signal serving as a down count input is output to the up / down counter 231 of the circuit 230.
[0059]
In the D / A converter 242C, a frequency control voltage value corresponding to the counter value of the up / down counter 242B is set. When the D / A converter 242C receives the counter value output from the up / down counter 242B, the D / A converter 242C changes the frequency control voltage signal SVC corresponding to the frequency control voltage value corresponding to the counter value to the variable of the drive signal supply unit 210. Output to the frequency oscillation circuit 212.
Each counter value and frequency control voltage value in the D / A converter 242C correspond to the drive frequency of the drive voltage signal SDR. In the present embodiment, the counter value, the frequency control voltage value, and the drive frequency of the drive voltage signal SDR have the relationship shown in Table 2 below.
[0060]
[Table 2]

[0061]
The control circuit 243 appropriately outputs a control command signal to the comparison voltage setting circuit 230 and the integration circuit 242 between the start of driving of the piezoelectric actuator A and the end of driving, thereby controlling these circuits 230 and 242. As shown in FIG. 19, the control circuit 243 includes a pulse generation source 243A, a differentiation circuit 243B, and a timer circuit 243C as a measuring means.
The pulse generation source 243A is a circuit that outputs a pulse signal CLK having a predetermined frequency from a reference oscillation signal such as a crystal resonator or a ceramic resonator. For example, the pulse generation source 243A outputs the pulse signal CLK to the two AND gates 242A1 and 242A2 of the integrating circuit 242 and the timer circuit 243C.
[0062]
When the differentiating circuit 243B inputs a start signal indicating the start of driving of the piezoelectric actuator A, ie, a start signal indicating the start of rotation of the date dial 50 (FIG. 1), indicating midnight, the input timing of the start signal Is a circuit that outputs a pulse signal STA in accordance with the above. The differentiating circuit 243B outputs a pulse signal STA to the up / down counter 231 of the comparison voltage setting circuit 230, the up / down counter 242B of the integrating circuit 242 and the timer circuit 243C.
The timer circuit 243C is a circuit that measures the driving time of the piezoelectric actuator A. The timer circuit 243C measures the driving time of the piezoelectric actuator A based on the pulse signal CLK output from the pulse generation source 243A with the pulse signal STA output from the differentiation circuit 243B as a trigger. The timer circuit 243C outputs a signal TIM to be input to the up / down counter 231 of the comparison voltage setting circuit 230 when the measured time has elapsed for a predetermined time.
[0063]
[5. Driving method of piezoelectric actuator A]
FIG. 20 is a flowchart for explaining a method of driving the piezoelectric actuator A. FIG. 21 is a diagram illustrating a method for driving the piezoelectric actuator A.
In the following, the drive voltage signal output from the drive signal supply unit 210 so that the drive control unit 240 has a value near zero between the phase difference detected by the phase difference detection unit 220 and the reference phase difference. The drive control for locking the SDR drive frequency near the optimum design drive frequency f0 will be described in two parts.
[0064]
[5-1. Driving method with design frequency characteristics]
First, when the frequency characteristic in the phase difference has a design characteristic, for example, as shown in FIG. 21, when the applied pressure is 3 g (graph A), the following drive control is performed. The
When the differentiation signal 243B of the drive control means 240 receives the start signal, it outputs a pulse signal STA to the up / down counter 231 of the comparison voltage setting circuit 230, and the counter value of the up / down counter 231 is set to MAX (7). (Step S1: Reference phase difference setting step). That is, as shown in Table 1, the reference phase difference is set to 90 °, and the comparison voltage setting circuit 230 outputs the comparison voltage signal SREF corresponding to the phase difference of 90 ° to the comparison circuit 241 of the drive control means 240.
[0065]
Simultaneously with step S1, the differentiation circuit 243B outputs the pulse signal STA to the up / down counter 242B of the integration circuit 242, and the counter value of the up / down counter 231 is set to 0 (step S2). That is, as shown in Table 2, the frequency control voltage value output from the integration circuit 242 is set to 0, and the drive frequency of the drive voltage signal SDR output from the drive signal supply unit 210 is set to the minimum drive frequency fmin. (200 kHz).
Further, simultaneously with these steps S1 and S2, the differentiation circuit 243B outputs a pulse signal STA to the timer circuit 243C, and the timer circuit 243C measures the driving time of the piezoelectric actuator A.
[0066]
After step S2, a drive voltage signal SDR having a predetermined drive frequency (here, the minimum drive frequency fmin) is applied from the drive signal supply means 210 to the vibrator 10 of the piezoelectric actuator A, and the vibrator 10 vibrates. (Step S3: Drive signal supply step).
Due to the vibration of the vibrating body 10, detection signals SD1 and SD2 are output from the vibration detection electrodes T1 and T2. Then, the phase difference detection means 220 detects the phase difference φ between these detection signals SD1 and SD2, and outputs a phase difference signal SPD having a voltage value Vφ corresponding to the average phase difference to the comparison circuit 241 of the drive control means 240. (Step S4: Phase difference detection step).
[0067]
Then, in the comparison circuit 241, the drive control means 240 obtains the comparison voltage value of the comparison voltage signal SREF output from the comparison voltage setting circuit 230 and the voltage value of the phase difference signal SPD output from the phase difference detection means 220. Compare (step S5: phase difference comparison step). That is, the comparison circuit 241 determines whether or not the phase difference φ detected by the phase difference detection means 220 is 90 ° or less, which is the reference phase difference. Here, as shown in FIG. 21, when a driving voltage signal SDR having a driving frequency of fmin (200 kHz) is applied to the vibrating body 10, the detected phase difference φ is substantially zero. That is, in step S3, the comparison circuit 241 determines that the voltage value of the phase difference signal SPD is less than or equal to the comparison voltage value of the comparison voltage signal SREF (“Yes”), and sends the signal SCTH to the integration circuit 242 of the drive control means 240. Is output.
[0068]
When the integration circuit 242 receives the signal SCTH, the up / down counter 242B counts up via the AND gate 242A1 and increments the counter value by 1 (step S6A: integration information calculation step).
In step S6A, when the count value of the up / down counter 242B increases by 1, the frequency control voltage value output from the integration circuit 242 increases from 0 to a predetermined value, and the drive voltage output from the drive signal supply unit 210 is increased. The drive frequency of the signal SDR increases from fmin (200 kHz) (step S7A: frequency adjustment step).
[0069]
In step S6A, when the up / down counter 242B counts up, the drive control means 240 determines whether or not the counter value of the up / down counter 242B exceeds the MAX value (4095, see Table 2) (step S8: drive). Control determination step). That is, here, the drive control means 240 determines whether or not the drive control has failed. And when it determines with "No" in step S8, it returns to step S3 again. Thus, if the determination in step S5 is “Yes” and the determination in step S8 is “No”, the counter value of the up / down counter 242B continues to increase. That is, the drive control means 240 is within the range of the set minimum drive frequency fmin (200 kHz) to the set maximum drive frequency fmax (400 kHz, see Table 2) corresponding to the counter value MAX of the up / down counter 242B. The drive frequency of the drive voltage signal SDR is increased.
[0070]
Steps S3 to S5, S6A, S7A, and S8 are repeatedly performed to increase the drive frequency of the drive voltage signal SDR, so that the drive frequency of the drive voltage signal SDR is the optimum drive frequency f0 (300 kHz in design). ). At this time, in step S5, the comparison circuit 241 determines that the voltage value of the phase difference signal SPD is larger than the comparison voltage value of the comparison voltage signal SREF (“No”), and sends a signal to the integration circuit 242 of the drive control unit 240. Output SCTL.
When the integration circuit 242 receives the signal SCTL, the up / down counter 242B counts down through the AND gate 242A2 and decreases the counter value by 1 (step S6B: integration information calculation step).
[0071]
In step S6B, when the count value of the up / down counter 242B decreases by 1, the frequency control voltage value output from the integration circuit 242 decreases by a predetermined value, and the drive voltage signal output from the drive signal supply unit 210 is output. The SDR drive frequency is decreased by a predetermined value (step S7B: frequency adjustment step).
After step S7B, the drive control means 240 determines whether or not the time measured by the timer circuit 243C has elapsed for a predetermined time (step S9). Here, when it determines with "No", it returns to step S3 again. As described above, when the frequency characteristic in the phase difference has a design characteristic, for example, when the applied pressure is 3 g, the step S3 to the step S9 are sequentially repeated to detect the phase difference. The phase difference φ detected by the means 220 becomes substantially equal to the reference phase difference of 90 °, and the drive frequency of the drive voltage signal SDR is locked near the optimum drive frequency f0 (300 kHz).
The phase difference comparison step S5, the integration information calculation steps S6A and S6B, and the frequency adjustment steps S7A and S7B correspond to the drive control step according to the present invention.
[0072]
[5-2. Driving method when design frequency characteristics are changing]
Next, when the frequency characteristic in the phase difference is changed from the design characteristic, for example, as shown in FIG. 21, when the applied pressure is from 3 g to 5 g (graph B), The drive control shown in FIG.
Here, as shown in FIG. 21, the phase difference in the graph B is at a position lower than the reference phase difference (90 °) set in step S1. For this reason, even if the above-described steps S3 to S5, S6A, S7A, and S8 are repeatedly performed and the drive frequency of the drive voltage signal SDR exceeds the optimum drive frequency f0 (300 kHz) in design, the comparison circuit in step S5. 241 determines that the voltage value of the phase difference signal SPD is smaller than the comparison voltage value of the comparison voltage signal SREF (“Yes”).
[0073]
As a result, in step S6A, the up / down counter 242B continues to count up, and the counter value reaches MAX (4095, see Table 2). That is, the drive frequency of the drive voltage signal SDR is increased from the set minimum drive frequency fmin (200 kHz) shown in Table 2 to the maximum drive frequency fmax (400 kHz).
Then, in step S8, the drive control means 240 further determines that the count value of the up / down counter 242B has exceeded the value of MAX (“Yes”) as the up / down counter 242B further counts up. That is, here, the drive control means 240 determines that the drive control has failed.
[0074]
In step S8, when the counter value of up / down counter 242B exceeds the value of MAX, carry occurs in up / down counter 242B, and the counter value of up / down counter 242B is switched to 0 (step S10). Similarly to step S2, the frequency control voltage value output from the integration circuit 242 is set to 0, and the drive frequency of the drive voltage signal SDR output from the drive signal supply means 210 is set to the minimum drive frequency fmin ( 200 kHz).
At the same time as step S10, the up / down counter 242B outputs a signal serving as a down count input to the up / down counter 231 of the comparison voltage setting circuit 230, and the up / down counter 231 decreases the counter value by 1 from the value of MAX. (Step S11). That is, as shown in Table 1, the up / down counter 231 counts down the counter value from MAX (7) to 6, and is set to 80 °, where the reference phase difference is reduced by 10 ° from 90 °. Then, the comparison voltage setting circuit 230 outputs a comparison voltage signal SREF corresponding to a phase difference of 80 ° to the comparison circuit 241 of the drive control means 240.
[0075]
After step S11, the drive control means 240 repeatedly performs steps S3 to S5, S6A, S7A, and S8 in substantially the same manner as described above. That is, the drive control means 240 increases the drive frequency of the drive voltage signal SDR in the range from the set minimum drive frequency fmin to the maximum drive frequency fmax, and the phase difference φ detected by the phase difference detection means 220 is the reference. An attempt is made to find a position where the phase difference is larger than 80 °. However, as shown in FIG. 21, the phase difference in the graph B is at a position lower than the reference phase difference (80 °) set in step S11. For this reason, as in the case where the reference phase difference is 90 °, the drive frequency of the drive voltage signal SDR increases up to the set maximum drive frequency fmax.
As described above, the drive control unit 240 decreases the counter value of the up / down counter 231 by 1 and decreases the reference phase difference by 10 °, while the phase difference φ detected by the phase difference detection unit 220 is greater than the reference phase difference. Steps S3 to S5, S6A, S7A, S8, S10, and S11 are sequentially performed until the value increases. In this embodiment, as shown in FIG. 19, in steps S9, until the counter value of the up / down counter 231 becomes 4, and the reference phase difference is set to 60 °, steps S3 to S5, S6A, S7A, S8, S10 and S11 are sequentially performed.
[0076]
In step S11, after the reference phase difference is set to 60 °, steps S3 to S5, S6A, S7A, and S8 are repeatedly performed, so that the drive frequency of the drive voltage signal SDR is the optimum drive frequency f0 in design. (300 kHz) is exceeded. In step S3, it is determined that the phase difference φ is larger than the reference phase difference 60 ° (“No”).
Thereafter, the process proceeds to step S6B. In step S6B, the up / down counter 242B decreases the counter value by 1, and in step S7B, the drive frequency of the drive voltage signal SDR is decreased by a predetermined value. Then, in step S9, the drive control means 240 determines whether or not the time measured by the timer circuit 243C has elapsed for a predetermined time. If it is determined “No”, the drive control means 240 returns to step S3 again. The drive frequency of the drive voltage signal SDR is adjusted. As described above, when the frequency characteristic in the phase difference is changed from the designed characteristic, for example, when the applied pressure is changed from 3 g to 5 g, the steps S3 to S11 are repeatedly performed. The phase difference φ detected by the phase difference detecting means 220 is substantially equal to the reference phase difference, for example, 60 °, and the drive frequency of the drive voltage signal SDR is locked near the optimum drive frequency f0 (300 kHz).
[0077]
Here, for example, after the reference phase difference is set to 60 ° and the drive frequency of the drive voltage signal SDR is locked based on the reference phase difference (60 °), the frequency characteristic in the phase difference is a design characteristic. In the case of returning to, the drive frequency of the drive voltage signal SDR is locked in the vicinity of f1 shown in FIG. That is, the drive frequency of the drive voltage signal SDR is locked at a position different from the optimum drive frequency f0 (300 kHz).
For this reason, the drive control means 240 determines in step S9 whether or not the time measured by the timer circuit 243C has elapsed a predetermined time. If the determination is “Yes”, the timer circuit 243C outputs a signal TIM to be input to the up / down counter 231 of the comparison voltage setting circuit 230.
Then, the up / down counter 231 receives the signal TIM and increases the counter value by 1 (step S12). That is, the up / down counter 231 counts up the counter value from 4 to 5, and the reference phase difference is set to 70 ° increased from 60 ° to 10 °. Then, the comparison voltage setting circuit 230 outputs a comparison voltage signal SREF corresponding to a phase difference of 70 ° to the comparison circuit 241 of the drive control unit 240.
[0078]
After step S12, the drive control means 240 repeatedly performs step S3 to step S11 in substantially the same manner as described above. As a result, the drive frequency of the drive voltage signal SDR is locked in the vicinity of the drive frequency f2 (FIG. 21) at which the phase difference φ detected by the phase difference detecting means 220 is approximately equal to 70 ° which is the reference phase difference. As described above, the drive control unit 240 sequentially performs step S3 to step S11, and increases the reference phase difference by 10 ° in step S12 every predetermined time in step S9. Then, the driving frequency of the driving voltage signal SDR is changed in the order of the driving frequencies f1, f2, and f3 shown in FIG. 21, and finally locked near the optimum driving frequency f0 (300 kHz).
[0079]
When the piezoelectric actuator A is driven by the control by the driving device 200 described above, the rotor 100 rotates, and accordingly, the date driving intermediate wheel 40 (FIG. 1) rotates. And in the process in which the intermediate date wheel 40 rotates, the leaf spring 64 and the contact 65 come into contact. By detecting this contact state, it is detected that the date wheel 50 has been rotated by one tooth (corresponding to a date range for one day), and the driving device 200 stops driving the piezoelectric actuator A.
[0080]
[6. Effects of the embodiment]
The embodiment described above has the following effects.
(1) The drive control unit 240 calculates the comparison voltage value of the comparison voltage signal SREF output from the comparison voltage setting circuit 230 by the comparison circuit 241 and the voltage value of the phase difference signal SPD output from the phase difference detection unit 220. The comparison information is calculated by comparison, and the integration circuit 242 integrates the comparison information to calculate integration information. Then, the drive control means 240 sequentially increases the drive frequency of the drive voltage signal SDR from the minimum drive frequency fmin to the maximum drive frequency fmax based on the integration information, and the difference between the phase difference φ and the reference phase difference is close to zero. As shown, the drive control is performed to lock the drive frequency of the drive voltage signal SDR near the optimum drive frequency f0. In addition, the drive control means 240 determines whether or not the drive control is successful based on the integration information. Thereby, for example, even when the frequency characteristic in the phase difference is changed due to a change in the applied pressure, the change can be appropriately recognized. When the drive control unit 240 determines that the drive control is unsuccessful, the drive control unit 240 causes the comparison voltage setting circuit 230 to change the set value of the reference phase difference, and performs drive control based on the changed reference phase difference. . Thus, the drive frequency of the drive signal can be adjusted based on an appropriate reference phase difference. That is, even when the frequency characteristic in the phase difference changes, the drive voltage signal SDR having the optimum drive frequency f0 can be applied to the piezoelectric actuator A.
[0081]
(2) Further, the drive control means 240 determines whether or not the drive control is successful in the process of controlling the drive signal supply means 210, that is, in the process of calculating the counter value by adding the comparison information. Separately, for example, a member such as a frequency counter is not required, and the configuration of the driving device 200 can be simplified.
[0082]
(3) The integration circuit 242 includes AND gates 242A1 and 242A2, an up / down counter 242B, and a D / A converter 242C. The comparison circuit 241 uses the comparison information depending on whether the comparison voltage value of the comparison voltage signal SREF output from the comparison voltage setting circuit 230 is equal to or less than the voltage value of the phase difference signal SPD output from the phase difference detection unit 220. A high level signal SCTH and a low level signal SCTL are output. The up / down counter 242B counts up or down in accordance with the signals SCTH and SCTL, and the counter SC exceeds the MAX value as a result of continuous input of the signal SCTH. A control signal is output to the setting circuit 230. Thereafter, the comparison voltage setting circuit 230 receives the control signal to decrease the set value of the reference phase difference by 10 °. As a result, the drive control unit 240 can easily recognize the change in the frequency characteristic due to the phase difference with a simple configuration, and the change in the frequency characteristic due to the phase difference is automatically determined. Based on this, drive control can be performed quickly.
[0083]
(4) The comparison voltage setting circuit 230 includes an up / down counter 231 and a D / A converter 232. A comparison voltage value corresponding to the counter value of the up / down counter 231 is set in the D / A converter 232, and the comparison voltage value corresponds to a reference phase difference. Thus, by inputting a control signal from the drive control means 240, the up / down counter 231 can switch the counter value, and the reference phase difference can be easily set and changed. Further, the circuit configuration is simplified, and the control of the comparison voltage setting circuit 230 can be easily performed.
[0084]
(5) The drive control means 240 has a timer circuit 243C, and this timer circuit 243C measures the drive time of the piezoelectric actuator A. Then, when the measurement time of the timer circuit 243C has elapsed for a predetermined time, the drive control unit 240 increases the set value of the reference phase difference by 10 ° in the comparison voltage setting circuit 230, and drives based on the changed reference phase difference. Implement control. As a result, after the drive control by the drive control means 240 is successful, for example, even when the pressure is changed from 5 g to 3 g and the frequency characteristic in the phase difference is changed, the drive voltage signal SDR is driven. The frequency can be locked near the optimum drive frequency f0.
[0085]
(6) When the differentiation circuit 243B of the drive control means 240 receives a start signal indicating the start of driving of the piezoelectric actuator A, it outputs a pulse signal STA to the up / down counter 231 of the comparison voltage setting circuit 230. The up / down counter 231 of the comparison voltage setting circuit 230 sets the counter value to 0, and the reference phase difference is set to 90 °, which is an initial value. As a result, even when the frequency characteristic in the phase difference changes compared to the previous driving, the driving frequency of the driving voltage signal SDR can always be adjusted to the optimum driving frequency f0.
[0086]
(7) The timepiece includes the piezoelectric actuator A and the driving device 200, and the driving device 200 always applies the driving voltage signal SDR having the optimum driving frequency f0 to the piezoelectric actuator A. Thus, the piezoelectric actuator A can be excited with predetermined longitudinal vibration and bending vibration, and can drive the calendar display mechanism with high efficiency.
[0087]
[7. Variation of Embodiment]
In addition, this invention is not limited to the said embodiment, The deformation | transformation as shown below is also included.
For example, in the embodiment, the drive control unit 240 includes the comparison circuit 241, which compares the comparison voltage value of the comparison voltage signal SREF output from the comparison voltage setting circuit 230 with the phase difference detection unit 220. Although the binary information indicating the magnitude is output between the voltage value of the phase difference signal SPD output from the above, the present invention is not limited to this. For example, the configuration may be such that absolute value information is output by subtracting the comparison voltage value of the comparison voltage signal SREF and the voltage value of the phase difference signal SPD. Here, the drive control means 240 implements drive control that integrates absolute value information and changes the drive frequency of the drive voltage signal SDR based on the integration information. In such a configuration, when the drive control unit 240 changes the drive frequency of the drive voltage signal SDR from the minimum drive frequency fmin to the maximum drive frequency fmax, for example, the phase difference detected with respect to the comparison voltage value is detected. When there is a significant difference between the voltage values, the drive frequency can be changed greatly, and the drive frequency can be quickly locked in the vicinity of the optimum drive frequency f0.
At this time, a loop filter that smoothes the absolute value information can be employed as the integration circuit 242 of the drive control means 240.
[0088]
In the embodiment, the drive control unit 240 increases the drive frequency of the drive voltage signal SDR from the minimum drive frequency fmin to the maximum drive frequency fmax when performing the drive control. However, the present invention is not limited to this. For example, a configuration may be adopted in which drive control is performed by reducing the drive frequency of the drive voltage signal SDR from the maximum drive frequency fmax to the minimum drive frequency fmin. At this time, the up / down counter 242B of the drive control means 240 continuously counts down, and outputs a control signal to the up / down counter 231 of the comparison voltage setting circuit 230 when the counter value becomes zero. That is, when the counter value becomes 0, it is determined that the drive control has failed. Then, the counter value of the up / down counter 231 of the comparison voltage setting circuit 230 is switched, and the reference phase difference is changed.
[0089]
In the embodiment, the drive control unit 240 outputs a control signal to the up / down counter 231 of the comparison voltage setting circuit 230 when the count value of the up / down counter 242B exceeds MAX and a carry occurs. That is, when carry occurs in the up / down counter 242B, the drive control unit 240 determines that the drive control has failed and lowers the set value of the reference phase difference by 10 °. Not limited to this configuration, when the count value of the up / down counter 242B becomes a value corresponding to the circuit characteristics of the variable frequency oscillation circuit 212 of the drive signal supply means 210, it is determined that the drive control has failed, and the reference You may employ | adopt the structure which changes the setting value of a phase difference. For example, when the temperature characteristic of the oscillation frequency of the variable frequency oscillation circuit 212 has a frequency fluctuation range of ± 50 kHz, the drive control means 240 is +50 kHz (350 kHz) with respect to the drive frequency f0 at which the counter value of the up / down counter 242B is optimum. ) Corresponding to 3072), it is determined that the drive control has failed. Then, the counter value of the up / down counter 242B is set to 1024 corresponding to −50 kHz (250 kHz) with respect to the optimum driving frequency f0, and a control signal is output to the up / down counter 231 of the comparison voltage setting circuit 230 to increase the counter value. The counter value of the down counter 231 is decreased by 1, and the set value of the reference phase difference is decreased by 10 °. With such a configuration, the drive control means 240 can adjust the drive frequency of the drive voltage signal SDR within the minimum required range (drive frequency 250 kHz to 350 kHz), and can quickly perform drive control.
[0090]
In the embodiment, the drive control unit 240 changes the reference phase difference setting value to the initial value (90 °) at the comparison voltage setting circuit 230 when driving of the piezoelectric actuator A is started. The following configuration may be adopted.
For example, the driving device 200 includes storage means for storing reference phase difference information related to the reference phase difference set by the comparison voltage setting circuit 230. Then, when the drive control unit 240 starts driving the piezoelectric actuator A, based on the previous reference phase difference information stored in the storage unit, the setting value of the reference phase difference is supplied to the comparison voltage setting circuit 230, for example, The previous reference phase difference or a value larger than the previous reference phase difference is set. In such a configuration, drive control can be performed in substantially the same state as in the previous drive, and when the frequency characteristic in the phase difference has not changed from the previous drive, the drive frequency of the drive voltage signal SDR can be quickly set. It can be locked near the optimum drive frequency f0.
[0091]
In the embodiment, the phase difference detection unit 220 detects the phase difference between the detection signals SD1 and SD2 output from the vibration detection electrodes T1 and T2, but the present invention is not limited to this. That is, the phase difference detection unit 220 detects the phase difference between any two of the drive voltage signal SDR output from the drive signal supply unit 210 and the detection signals SD1 and SD2 output from the vibration detection electrodes T1 and T2. It is good also as composition to do.
In the above-described embodiment, the optimum driving frequency has been described as 300 kHz, but this value is appropriately changed depending on the design of the piezoelectric actuator A. Further, the adjustment width of the driving frequency according to the counter value of the up / down counter 242B and the adjustment width (10 °) of the reference phase difference according to the counter value of the up / down counter 231 may be set to other values.
[0092]
In the above-described embodiment, the comparison voltage setting circuit 230 is configured to include the up / down counter 231 and the D / A converter 232, but is not limited thereto. For example, the comparison voltage setting circuit 230 may be composed of an up / down counter 231 and a plurality of constant voltage generation circuits. For example, the up / down counter 231 counts up or down according to a control command from the drive control unit 240, and any one of the plurality of constant voltage generation circuits according to the counter value A comparison voltage signal SREF corresponding to a predetermined voltage value is output to the comparison circuit 241. Thus, setting and changing the reference phase difference can be easily performed by making the counter value and the number of constant voltage generation circuits to be driven correspond to the reference phase difference. In addition, the configuration having the constant voltage generation circuit can suppress fluctuations in the reference phase difference.
[0093]
In the above-described embodiment, the configuration in which the timepiece includes the piezoelectric actuator A and the driving device 200 that drives the piezoelectric actuator A has been described. However, the configuration is not limited thereto, and the configuration is provided in, for example, the following non-contact IC card A configuration provided in another electronic device may be employed.
FIG. 22 is a perspective view showing the appearance of a non-contact type IC card. FIG. 23 is a diagram showing an internal configuration of the non-contact type IC card.
On the surface side of the non-contact type IC card 400, as shown in FIG. 22, a balance display counter 401 for performing a balance display is provided. The balance display counter 401 displays a 4-digit balance, and includes a display unit 402 that displays the upper 2 digits and a display unit 403 that displays the lower 2 digits, as shown in FIG.
[0094]
FIG. 24 is a side view showing the configuration of the upper digit display unit 402.
The upper digit display unit 402 is connected to the piezoelectric actuator A1 via the rotor 100A and is driven by the driving force of the rotor 100A. The main part of the upper digit display unit 402 has a feed claw 402A, and when the rotor 100A rotates 1 / n, the driving gear 402A rotates once, and the first upper digit display rotates one scale by one rotation of the driving gear 402A. The first upper digit display vehicle 402B is fixed when the car 402B, the first upper digit display vehicle 402B, and the second upper digit display vehicle 402C that rotates by one scale by one rotation and the first upper digit display vehicle 402B do not rotate. And a fixing member 402D. The second upper digit display wheel 402B is also provided with a fixing member (not shown) that fixes the second upper digit display wheel 402C.
[0095]
The drive gear 402A rotates once when the rotor 100A rotates 1 / n. The feed pawl 402A meshes with the feed gear portion 402B3 of the first upper digit display wheel 402B, and the first upper digit display wheel 402B rotates by one scale.
Note that rotating the rotor 100A by 1 / n is an example of the operation, and the present invention is not limited to this. Moreover, it is an example of operation | movement that the drive gear 402A rotates 1 time, and rotates the 1st high-order digit display wheel 402B by one scale, It is not limited to this.
[0096]
Further, when the first upper digit display wheel 402B rotates and rotates once, the feed pin 402B provided in the first upper digit display wheel 402B rotates the feed gear 402B2, and the second gear gear 402B is engaged. The feed gear 402C of the upper digit display wheel 402C is rotated, and the second upper digit display wheel 402C is rotated by one scale.
The lower digit display unit 403 is connected to the piezoelectric actuator A2 via the rotor 100B, and is driven by the driving force of the rotor 100B. The main part of the lower digit display unit 403 includes a feed claw 403A1, and a driving gear 403A that rotates once when the rotor 100B rotates 1 / n, and a first lower digit display that rotates one graduation by one rotation of the driving gear 403A. A vehicle 403B and a second lower display wheel 403C that rotates by one graduation by one rotation of the first lower digit display wheel 403B are provided.
[0097]
FIG. 25 is a front view of the lower digit display unit 403. FIG. 26 is a side view of the lower digit display unit 403.
The first lower digit display wheel 403B has a feed gear portion 403B1 that meshes with the feed claw 403A1 of the drive gear 403A, and rotates one scale by one rotation of the drive gear 403A.
The first lower digit display wheel 403B is provided with a feed pin 403B2. Each time the first lower digit display wheel 403B makes one rotation, the feed gear 403B3 is rotated to change the second lower digit display wheel 403C. Rotate by one scale.
In this case, the fixing member 403D of the first lower digit display portion 403B meshes with the feed gear portion 403B1 to fix the first lower digit display wheel 403B when not rotating. Further, the fixing member 403E of the second lower digit display wheel 403C meshes with the feed gear portion 403F to fix the second lower digit display wheel 403C when the second lower digit display wheel 403C is not rotating.
In this case, the actuator A1 and the actuator A2 are set to be driven synchronously by the drive device 200, and the drive device 200 receives a drive control signal corresponding to the settlement amount by an IC card chip (not shown). It is driven by.
[0098]
In the above-described embodiment, the drive control means 240 that executes the flow shown in FIG. 20 may be configured to function as a computer by arranging a CPU (Control Processing Unit), a memory, and the like in addition to a logic circuit. . In this case, a predetermined program is incorporated in the computer so that the function of the drive control means 240 is realized.
For example, a predetermined control program is installed in the memory via a communication unit such as the Internet or a recording medium such as a CD-ROM or a memory card, and the CPU or the like is operated by the installed program to drive control unit 240. Realize the function.
In order to install a predetermined program in an electronic device such as a watch, a device that reads a storage medium such as a memory card or a CD-ROM may be externally connected to the electronic device. Further, a LAN cable, a telephone line, or the like may be connected to an electronic device and the program may be supplied and installed by communication, or the program may be supplied and installed wirelessly.
In addition, a control program may be incorporated in advance in a memory configured in an electronic device such as a clock, and the function of the drive control unit 240 may be realized by the CPU. In this case, the control program may be installed in the memory later, and may be installed via the Internet or a recording medium such as a CD-ROM or a memory card.
【The invention's effect】
As described above, according to the present invention, there is an effect that an optimum driving frequency can be applied even when the frequency characteristic of the phase difference changes due to various factors.
[Brief description of the drawings]
FIG. 1 is a plan view showing a configuration of a calendar display mechanism of a wristwatch incorporating a piezoelectric actuator according to an embodiment.
FIG. 2 is a cross-sectional view of the timepiece according to the embodiment.
FIG. 3 is a cross-sectional view showing a detailed configuration of a calendar display mechanism in the embodiment.
FIG. 4 is a plan view showing a detailed configuration of the piezoelectric actuator in the embodiment.
5 is a cross-sectional view taken along line VV of the piezoelectric actuator in FIG.
FIG. 6 is a diagram illustrating an example of an arrangement position of a drive electrode and a vibration detection electrode provided on the vibrating body in the embodiment.
FIG. 7 is a diagram showing an example of a polarization state of the piezoelectric element in the embodiment.
FIG. 8 is a diagram showing an example of a polarization state of the piezoelectric element in the embodiment.
FIG. 9 is a diagram showing bending vibration generated in the vibrating body in the embodiment.
FIG. 10 is a diagram illustrating a movement state of the contact portion due to vibration of the vibrating body in the embodiment.
FIG. 11 is a view showing a modification of the arrangement of the vibration detection electrode pairs in the embodiment.
FIG. 12 is a view showing a modification of the arrangement of vibration detection electrode pairs in the embodiment.
FIG. 13 is a diagram showing a trajectory drawn by the contact portion of the vibrating body in the embodiment.
FIG. 14 is a diagram illustrating an example of a change in frequency characteristics in a phase difference between longitudinal vibration and bending vibration of the vibrating body in the embodiment.
FIG. 15 is a block diagram showing a configuration of a drive device for a piezoelectric actuator in the embodiment.
FIG. 16 is a block diagram showing a configuration of a phase difference-DC conversion circuit in the embodiment.
FIG. 17 is a view showing waveforms processed in the phase difference-DC conversion circuit in the embodiment.
FIG. 18 is a view showing waveforms processed in the phase difference-DC conversion circuit in the embodiment.
FIG. 19 is a diagram showing a configuration of a comparison voltage setting circuit and drive control means in the embodiment.
FIG. 20 is a flowchart for explaining a driving method of the piezoelectric actuator in the embodiment.
FIG. 21 is a diagram for explaining a driving method of the piezoelectric actuator in the embodiment.
FIG. 22 is a view showing a modification of the embodiment.
FIG. 23 is a view showing a modification of the embodiment.
FIG. 24 is a view showing a modification of the embodiment.
FIG. 25 is a view showing a modification of the embodiment.
FIG. 26 is a view showing a modification of the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Vibrating body 30,31 ... Piezoelectric element, 210 ... Drive signal supply means, 220 ... Phase difference detection means, 230 ... Comparison voltage setting circuit (reference phase difference setting means), 231 ... Up / down counter, 240 ... drive control means, 242B ... up / down counter, 243C ... timer circuit, A ... piezoelectric actuator, S1 ... reference phase difference setting step, S3. ..Drive signal supply step, S4... Phase difference detection step, S5... Phase difference comparison step, S6A, S6B... Integration information calculation step, S7A, S7B. Drive control determination step.

Claims (13)

A vibrating body that has a piezoelectric element and vibrates in a first vibration mode when a drive signal having a predetermined driving frequency is given to the piezoelectric element and vibrates in a second vibration mode having a different vibration direction. A drive device for a piezoelectric actuator comprising:
Drive signal supply means for supplying the drive signal to the vibrator;
A detection signal representing vibration in the first vibration mode and / or the second vibration mode is detected from the vibrating body, and a phase difference between any two of the drive signal and the detection signal is detected. Phase difference detection means;
A reference phase difference setting means for setting a reference phase difference serving as a reference for a phase difference between any two signals of the drive signal and the detection signal;
Comparing the detected phase difference and the reference phase difference to calculate comparison information indicating a difference between the phase difference and the reference phase difference, and calculating the integration information by integrating the comparison information, Drive control means for performing drive control for causing the drive signal supply means to change the drive frequency of the drive signal based on integration information; and
The drive control means determines whether or not the drive control has succeeded based on the integration information, and when it is determined that the drive control has failed, the reference phase difference setting means sets a reference phase difference. A drive device for a piezoelectric actuator, wherein a value is changed and the drive control based on the changed reference phase difference is performed. In the drive device of the piezoelectric actuator according to claim 1,
The drive control means has an up / down counter,
The comparison information is information indicating the magnitude of the detected phase difference with respect to the reference phase difference,
The piezoelectric actuator driving apparatus according to claim 1, wherein the integrated information is a counter value calculated by the up / down counter counting up or down according to the comparison information. The drive device for a piezoelectric actuator according to claim 2,
The drive control means determines that the drive control is unsuccessful when a carry occurs as a result of the up / down counter calculating the counter value. The drive device for a piezoelectric actuator according to claim 2,
The drive control means determines that the drive control is unsuccessful when the counter value becomes 0 as a result of the counter value being calculated by the up / down counter. . The drive device for a piezoelectric actuator according to claim 2,
The drive control means determines that the drive control is unsuccessful when the up / down counter reaches a predetermined counter value according to the characteristics of the drive signal supply means as a result of calculating the counter value. A drive device for a piezoelectric actuator characterized by the above. In the drive device of the piezoelectric actuator according to any one of claims 1 to 5,
The reference phase difference setting means sets an up / down counter that counts up or down according to a control command from the drive control means to calculate a counter value, and sets a reference phase difference according to the counter value. A drive device for a piezoelectric actuator, comprising: a converter. In the drive device of the piezoelectric actuator according to any one of claims 1 to 5,
The reference phase difference setting means includes an up / down counter that counts up or down according to a control command from the drive control means to calculate a counter value, and a plurality of constants that set a reference phase difference according to the counter value. A piezoelectric actuator driving apparatus comprising: a voltage generating circuit. In the drive device of the piezoelectric actuator in any one of Claims 1-7,
The drive control means has a timer for measuring the elapsed driving time of the piezoelectric actuator, and sets the reference phase difference in the reference phase difference setting means when the time measured by the timer reaches a predetermined time. A drive device for a piezoelectric actuator, wherein a value is changed and the drive control based on the changed reference phase difference is performed. In the drive device of the piezoelectric actuator according to any one of claims 1 to 8,
The drive control unit causes the reference phase difference setting unit to set a reference phase difference setting value to an initial value when starting to drive the piezoelectric actuator. In the drive device of the piezoelectric actuator according to any one of claims 1 to 8,
Comprising storage means for storing reference phase difference information relating to the reference phase difference set by the reference phase difference setting means;
The drive control unit causes the reference phase difference setting unit to set a reference phase difference based on previous reference phase difference information stored in the storage unit when starting the driving of the piezoelectric actuator. A driving device for a piezoelectric actuator. A vibrating body that has a piezoelectric element and vibrates in a first vibration mode when a drive signal having a predetermined driving frequency is given to the piezoelectric element and vibrates in a second vibration mode having a different vibration direction. A method for driving a piezoelectric actuator comprising:
A reference phase difference serving as a reference for a phase difference between any one of the drive signal and a detection signal representing vibration in the first vibration mode and / or the second vibration mode is set. A reference phase difference setting step;
A drive signal supplying step of supplying the drive signal to the vibrating body;
A detection signal representing vibration in the first vibration mode and / or the second vibration mode is detected from the vibrating body, and a phase difference between any two of the drive signal and the detection signal is detected. A phase difference detection step;
A phase difference comparison step of comparing the detected phase difference and the reference phase difference to calculate comparison information indicating a difference between the phase difference and the reference phase difference; and integrating and calculating the calculated comparison information A drive control step configured by an integration information calculation step of calculating information, and a frequency adjustment step of changing the drive frequency of the drive signal based on the integration information;
A drive control determination step for determining whether or not the drive control step is successful based on the integration information,
When it is determined that the drive control determination step is unsuccessful, the reference phase difference set value set in the reference phase difference setting step is changed, and the drive control step is performed based on the changed reference phase difference. A method of driving a piezoelectric actuator, characterized in that A vibrating body that has a piezoelectric element and vibrates in a first vibration mode when a drive signal having a predetermined driving frequency is given to the piezoelectric element and vibrates in a second vibration mode having a different vibration direction. A timepiece comprising: a piezoelectric actuator comprising: a driving actuator according to any one of claims 1 to 10; A vibrating body that has a piezoelectric element and vibrates in a first vibration mode when a drive signal having a predetermined driving frequency is given to the piezoelectric element and vibrates in a second vibration mode having a different vibration direction. An electronic apparatus comprising: a piezoelectric actuator comprising: a driving actuator according to any one of claims 1 to 10;

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