JP2574293B2 - Ultrasonic motor driving method - Google Patents
Ultrasonic motor driving methodInfo
- Publication number
- JP2574293B2 JP2574293B2 JP62102258A JP10225887A JP2574293B2 JP 2574293 B2 JP2574293 B2 JP 2574293B2 JP 62102258 A JP62102258 A JP 62102258A JP 10225887 A JP10225887 A JP 10225887A JP 2574293 B2 JP2574293 B2 JP 2574293B2
- Authority
- JP
- Japan
- Prior art keywords
- phase difference
- driving
- ultrasonic motor
- voltage
- value
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 238000000034 method Methods 0.000 title claims description 6
- 239000000463 material Substances 0.000 claims description 2
- 238000010586 diagram Methods 0.000 description 6
- 238000005452 bending Methods 0.000 description 5
- 239000000919 ceramic Substances 0.000 description 3
- 239000002783 friction material Substances 0.000 description 2
- 238000005299 abrasion Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 230000012447 hatching Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
- H02N2/00—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction
- H02N2/10—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing rotary motion, e.g. rotary motors
- H02N2/14—Drive circuits; Control arrangements or methods
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
- H02N2/00—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction
- H02N2/10—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing rotary motion, e.g. rotary motors
- H02N2/16—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing rotary motion, e.g. rotary motors using travelling waves, i.e. Rayleigh surface waves
- H02N2/163—Motors with ring stator
Landscapes
- General Electrical Machinery Utilizing Piezoelectricity, Electrostriction Or Magnetostriction (AREA)
Description
【発明の詳細な説明】 産業上の利用分野 本発明は圧電体を用いて駆動力を発生する超音波モー
タの駆動方法に関する。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving method of an ultrasonic motor that generates a driving force by using a piezoelectric body.
従来の技術 近年圧電セラミック等の圧電体を用いた振動体に弾性
振動を励振し、これを駆動力とした超音波モータが注目
されている。2. Description of the Related Art In recent years, an ultrasonic motor that excites elastic vibrations in a vibrating body using a piezoelectric body such as a piezoelectric ceramic and uses this as a driving force has attracted attention.
以下、図面を参照しながら超音波モータの従来技術に
ついて説明を行う。Hereinafter, a conventional technique of an ultrasonic motor will be described with reference to the drawings.
第６図は円環形超音波モータの斜視図であり、円環形
の弾性体１の円環面の一方に圧電体として円環形圧電セ
ラミック２を貼合せて振動体３を構成している。４は耐
磨耗性材料の摩擦材、５は弾性体であり、互いに貼合せ
られて移動体６を構成している。移動体６は摩擦材４を
介して振動体３と接触している。圧電体２に電界を印加
すると振動体３の周方向に曲げ振動の進行波が励起さ
れ、移動体６を駆動する。尚、同図中の矢印は移動体６
の回転方向を示す。FIG. 6 is a perspective view of a toroidal ultrasonic motor, in which a vibrating body 3 is formed by bonding a toroidal piezoelectric ceramic 2 as a piezoelectric body to one of the toric surfaces of a toroidal elastic body 1. Reference numeral 4 denotes a friction material made of an abrasion-resistant material, and reference numeral 5 denotes an elastic body. The moving body 6 is in contact with the vibrating body 3 via the friction material 4. When an electric field is applied to the piezoelectric body 2, a traveling wave of bending vibration is excited in the circumferential direction of the vibrating body 3 to drive the moving body 6. The arrow in FIG.
Shows the direction of rotation.
第７図は第６図の超音波モータに使用した圧電セラミ
ック２の電極構造の一例を示している。同図では円周方
向に９波の弾性波がのるようにしてある。同図におい
て、ＡおよびＢはそれぞれ２分の１波長相当の小領域か
ら成る電極群で、Ｃは４分の３波長、Ｄは４分の１波長
の長さの電極である。電極ＣおよびＤは電極群ＡとＢに
位置的に４分の１波長（＝90度）の位相差を作ってい
る。電極ＡとＢ内の隣り合う小電極部は互いに反対に厚
み方向に分極されている。圧電体２の弾性体１との接着
面は、第７図に示めされた面と反対の面であり、電極は
ベタ電極である。使用時には、電極群ＡおよびＢは第７
図に斜線で示されたように、それぞれ短絡して用いられ
る。FIG. 7 shows an example of the electrode structure of the piezoelectric ceramic 2 used in the ultrasonic motor of FIG. In the figure, nine elastic waves are applied in the circumferential direction. In the figure, A and B are electrode groups each composed of a small area corresponding to a half wavelength, C is an electrode having a length of 3/4 wavelength, and D is an electrode having a length of a quarter wavelength. The electrodes C and D form a phase difference of a quarter wavelength (= 90 degrees) between the electrode groups A and B in position. The adjacent small electrode portions in the electrodes A and B are polarized in the thickness direction opposite to each other. The bonding surface of the piezoelectric body 2 to the elastic body 1 is a surface opposite to the surface shown in FIG. 7, and the electrodes are solid electrodes. In use, the electrode groups A and B are
As shown by hatching in the figure, each is used after being short-circuited.
以上のように構成された超音波モータの圧電体２の電
極ＡおよびＢに V1＝V0×sin（ωｔ） ……（１） V2＝V0×cos（ωｔ） ……（２） ただし、V0:電圧の瞬時値 ω：角周波数 t:時間 で表される電圧V1およびV2をそれぞれ印加すれば、振動
体３には ξ＝ξ０×（cos（ωｔ）×cos（kx） ＋sin（ωｔ）×sin（kx）） ＝ξ０×cos（ωｔ−kx） ……（２） ただし ξ：曲げ振動の振幅値 ξ0:曲げ振動の瞬時値 k:波数（２π／λ） λ：波長 x:位置 で表せる、円周方向に進行する曲げ振動が励起される。V 1 = V 0 × sin (ωt) (1) V 2 = V 0 × cos (ωt) (2) is applied to the electrodes A and B of the piezoelectric body 2 of the ultrasonic motor configured as described above. However, if voltages V 1 and V 2 represented by V 0 : instantaneous value of voltage ω: angular frequency t: time are respectively applied, に は = ξ 0 × (cos (ωt) × cos ( kx) + sin (ωt) × sin (kx)) = ξ 0 × cos (ωt-kx) ...... (2) where ξ: bending amplitude value of the vibration ξ 0: bending the instantaneous value k of the vibration wave number (2π / λ ): Bending vibration that progresses in the circumferential direction, which can be expressed by λ: wavelength x: position, is excited.
第８図は振動体３の表面のＡ点が進行波の励起によっ
て、長軸2w、短軸2uの楕円運動をし、振動体３上に加圧
して設置された移動体６が、楕円の頂点近傍で接触する
ことにより、摩擦力により波の進行方向とは逆方向にｖ
＝ω×ｕの速度で運動する様子を示している。FIG. 8 shows that the point A on the surface of the vibrating body 3 performs an elliptical motion of the long axis 2w and the short axis 2u by the excitation of the traveling wave, and the moving body 6 pressurized on the vibrating body 3 has an elliptical shape. By contact near the vertex, frictional force causes v
= Ω x u.
発明が解決しようとする問題点 上記の楕円軌跡の短軸は、振動体３の形状が決まれ
ば、曲げ振動の振幅に比例しているので、速度を大きく
するためには波の振幅を大きくしなければならない。ま
た、低電圧駆動で大きな振幅を得るためには、振動体の
共振周波数近傍で駆動しなければならない。ところが振
動体の共振特性は温度や負荷の変動によって変化するの
で、従来のように一定周波数で駆動したのでは、駆動周
波数と共振周波数の相対的関係が変化して超音波モータ
の特性が変化してしまう。また、超音波モータの振動体
の共振特性は、負荷が同じでも起動時と通常動作時では
異なる。そして、特に起動時に負荷の大きいときは振動
体の電気入力端子からみたインピーダンスが非常に大き
くなり、振動体に充分な振幅が励振できず、起動ができ
なくなるという問題点がある。Problems to be Solved by the Invention The short axis of the elliptical trajectory is proportional to the amplitude of the bending vibration when the shape of the vibrating body 3 is determined. Therefore, in order to increase the speed, the amplitude of the wave is increased. There must be. Further, in order to obtain a large amplitude by low voltage driving, the vibrating body must be driven near the resonance frequency. However, since the resonance characteristics of the vibrating body change due to changes in temperature and load, driving at a constant frequency as in the past changes the relative relationship between the driving frequency and the resonance frequency, changing the characteristics of the ultrasonic motor. Would. Further, the resonance characteristics of the vibrating body of the ultrasonic motor are different between the start-up and the normal operation even if the load is the same. In particular, when the load is large at the time of starting, the impedance seen from the electric input terminal of the vibrating body becomes very large, and there is a problem that the vibrating body cannot be excited with a sufficient amplitude and cannot be started.
本発明はかかる点に鑑みてなされたもので、温度や負
荷が変化しても、常に安定な動作をする超音波モータを
提供することを目的としている。The present invention has been made in view of such a point, and an object of the present invention is to provide an ultrasonic motor that always operates stably even when a temperature or a load changes.
問題点を解決するための手段 上記目的を達成するために、本発明の超音波モータの
駆動方法は、超音波モータの特性に従って圧電体を駆動
する駆動電圧の振幅値あるいはパルス幅を設定し、交流
駆動電圧と圧電体に流入する電流の位相差を制御パラメ
ータとし、最適動作点として第１の位相差を、第１の位
相差よりも大きな値に第２の位相差を設定し、起動時
に、第１の位相差と第２の位相差の間の値の位相差に相
当する周波数の交流駆動電圧で駆動を開始し、駆動時の
交流駆動電圧と流入電流の動作位相差と第１の位相差と
の差により交流駆動電圧の周波数を制御して、動作位相
差が第１の位相差の近傍になるように制御する。Means for Solving the Problems To achieve the above object, the driving method of the ultrasonic motor of the present invention sets the amplitude value or pulse width of the driving voltage for driving the piezoelectric body according to the characteristics of the ultrasonic motor, The phase difference between the AC drive voltage and the current flowing into the piezoelectric body is used as a control parameter, the first phase difference is set as an optimum operating point, and the second phase difference is set to a value larger than the first phase difference. , Driving is started with an AC driving voltage having a frequency corresponding to a phase difference of a value between the first phase difference and the second phase difference, and the operating phase difference between the AC driving voltage and the inflow current at the time of driving and the first The frequency of the AC drive voltage is controlled based on the difference from the phase difference, and the operation phase difference is controlled so as to be close to the first phase difference.
また、起動時に、第１の位相差と第２の位相差の間の
値の位相差に相当する周波数の交流駆動電圧で駆動を開
始し、動作位相差が第１の位相差の近傍になるように制
御して、動作位相差が第２の位相差以上になった時に
は、交流駆動電圧の振幅値あるいはパルス幅を設定値よ
りも大きくした後に再び前記の起動動作を開始し、一定
時間後に交流駆動電圧の振幅値あるいはパルス幅を設定
値に戻して、動作位相差と第１の位相差との差により交
流駆動電圧の周波数を制御して、動作位相差が前記第１
の位相差の近傍になるように制御する。Further, at the time of startup, driving is started with an AC drive voltage having a frequency corresponding to the phase difference between the first phase difference and the second phase difference, and the operation phase difference becomes close to the first phase difference. When the operating phase difference is equal to or larger than the second phase difference, the starting operation is started again after the amplitude value or pulse width of the AC drive voltage is made larger than the set value, and after a predetermined time, The amplitude value or pulse width of the AC drive voltage is returned to the set value, and the frequency of the AC drive voltage is controlled based on the difference between the operation phase difference and the first phase difference.
Is controlled so as to be in the vicinity of the phase difference.
作 用 超音波モータの特性に従って圧電体を駆動する駆動電
圧の振幅値あるいはパルス幅を設定し、超音波モータが
通常特性の時には、第１の位相差と第２の位相差の間の
値の位相差に相当する周波数の交流駆動電圧で駆動を開
始し、交流駆動電圧と流入電流の動作位相差と第１の位
相差との差により、動作位相差が第１の設定位相差の近
傍になるように駆動周波数を制御し、温度や負荷の変動
によって振動体の共振特性が変化して、振動体の共振周
波数と駆動周波数の相対的関係が変化しても、共振特性
の変化に追随して駆動周波数を変化させることにより相
対的関係を一定に保って超音波モータの特性をほぼ一定
にする。The amplitude or pulse width of the drive voltage for driving the piezoelectric body is set according to the characteristics of the ultrasonic motor. When the ultrasonic motor has the normal characteristics, the value of the value between the first phase difference and the second phase difference is set. Driving is started with an AC drive voltage having a frequency corresponding to the phase difference, and the operation phase difference becomes close to the first set phase difference due to the difference between the AC drive voltage and the operation phase difference between the inflow current and the first phase difference. The driving frequency is controlled so that the resonance characteristics of the vibrating body change due to changes in temperature and load, and the relative characteristics of the vibrating body and the driving frequency change. By changing the driving frequency, the relative relationship is kept constant and the characteristics of the ultrasonic motor are made almost constant.
また、超音波モータの何らかの原因により負荷が大き
くなって、起動時に、第１の位相差と第２の位相差の間
の値の位相差に相当する周波数の交流駆動電圧で駆動を
開始して、動作位相差が第１の設定位相差の近傍になる
ように駆動周波数を制御しても、動作位相差が第２の位
相差以上になった時には、交流駆動電圧の振幅値あるい
はパルス幅を設定値よりも大きくした後に再び前記の起
動動作を開始し、振動体に移動体を駆動するのに充分な
振幅値の進行波を励振して超音波モータを通常の状態に
戻して安定に起動し、一定時間後に交流駆動電圧の振幅
値あるいはパルス幅を設定値に戻して超音波モータの信
頼性を維持した後に、動作位相差と第１の位相差との差
により交流駆動電圧の周波数を制御して、動作位相差が
前記第１の位相差の近傍になるように制御することによ
り、温度や負荷の変動によって振動体の共振特性が変化
して、振動体の共振周波数と駆動周波数の相対的関係が
変化しても、共振特性の変化に追随して駆動周波数を変
化させることにより相対的関係を一定に保って超音波モ
ータの特性をほぼ一定にする。In addition, the load becomes large due to some cause of the ultrasonic motor, and at the time of startup, driving is started with an AC driving voltage having a frequency corresponding to a phase difference of a value between the first phase difference and the second phase difference. Even if the drive frequency is controlled so that the operation phase difference is close to the first set phase difference, when the operation phase difference becomes equal to or larger than the second phase difference, the amplitude value or pulse width of the AC drive voltage is changed. After the starting value is increased to a value larger than the set value, the above-described starting operation is started again, and the ultrasonic wave motor is returned to a normal state by exciting a traveling wave having a sufficient amplitude value to drive the moving body to the vibrating body, and is started stably. After a certain period of time, the amplitude or pulse width of the AC drive voltage is returned to the set value to maintain the reliability of the ultrasonic motor, and then the frequency of the AC drive voltage is changed by the difference between the operating phase difference and the first phase difference. Controlling the operating phase difference to be the first phase difference. By controlling to be close, the resonance characteristics of the vibrating body change due to changes in temperature and load, and even if the relative relationship between the resonance frequency of the vibrating body and the drive frequency changes, it follows changes in the resonance characteristics. By changing the driving frequency, the relative relationship is kept constant and the characteristics of the ultrasonic motor are made almost constant.
実施例 以下、図面に従って本発明の一実施例について詳細な
説明を行う。Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
第１図は本発明の超音波モータの駆動方法を実現する
具体回路のブロック図である。この回路が動作を開始す
ると、電圧制御発振器７は制御端子C1に入力された制御
電圧に従って発振する。この時の制御電圧は加算器８に
より、初期設定値Ｏがそのまま出力される。電圧制御発
振器７の出力は２分割され、一方は90度位相器９を通し
て電力増幅器10に、他方はそのまま電力増幅器11にそれ
ぞれ入力されて、振動体３を駆動するのに必要な値にま
で増幅される。電力増幅器10、11の出力は圧電体にそれ
ぞれ印加されて、振動体を駆動する。FIG. 1 is a block diagram of a specific circuit for realizing a driving method of an ultrasonic motor according to the present invention. This circuit starts to operate, the voltage controlled oscillator 7 oscillates according to the control voltage input to the control terminal C 1. At this time, the adder 8 outputs the control voltage at the initial setting value O as it is. The output of the voltage controlled oscillator 7 is divided into two, one of which is input to the power amplifier 10 through the 90-degree phase shifter 9 and the other is input to the power amplifier 11 as it is, and amplifies it to a value necessary for driving the vibrator 3 Is done. Outputs of the power amplifiers 10 and 11 are respectively applied to the piezoelectric bodies to drive the vibrating bodies.
圧電体の一方の入力端子には抵抗Ｒが接続されてお
り、圧電体に流れる電流を抵抗Ｒの両端電圧により、電
流検出器13で検出する。また、電圧検出器12は圧電体２
に印加される駆動電圧を検出する。位相差検出器14は電
流検出器13と電圧検出器12の出力から、圧電体２に印加
する駆動電圧と圧電体２へ流入する電流の位相差に比例
した電圧を発生する。位相比較器15は、位相差検出器14
の出力と動作設定値P1を比較し、その差に比例する電圧
を出力する。ただし、差が０の時は出力電圧は０になる
ようにしている。スイッチ18は制御器17によって回路始
動直後に閉じられている。従って、加算器８には設定電
圧Ｏと上記差に比例した電圧が入力され、２つの電圧の
和が出力される。加算器８の出力電圧は電圧制御発振器
７の制御端子C1に入力され、電圧制御発振器７は、設定
値P1と駆動時の位相差の差を小さくするように、駆動周
波数を変える。A resistor R is connected to one input terminal of the piezoelectric body, and a current flowing through the piezoelectric body is detected by a current detector 13 based on a voltage across the resistor R. The voltage detector 12 is a piezoelectric body 2
The driving voltage applied to is detected. The phase difference detector 14 generates a voltage proportional to the phase difference between the drive voltage applied to the piezoelectric body 2 and the current flowing into the piezoelectric body 2 from the outputs of the current detector 13 and the voltage detector 12. The phase comparator 15 is a phase difference detector 14
Compared outputs of the operation setting value P 1, and outputs a voltage proportional to the difference. However, when the difference is 0, the output voltage is set to 0. The switch 18 is closed by the controller 17 immediately after starting the circuit. Therefore, the set voltage O and a voltage proportional to the difference are input to the adder 8, and the sum of the two voltages is output. The output voltage of the adder 8 is input to the control terminal C 1 of the voltage controlled oscillator 7, the voltage controlled oscillator 7, so as to reduce the difference between the phase difference in driving the set value P 1, changing the driving frequency.
第２図は、第１図の具体回路の説明のための圧電体に
流入する電流と、駆動電圧と電流の位相差の周波数特性
である。同図において、実線は超音波モータのある動作
時の特性を表し、点線は別の動作時の特性を表わしてい
る。f0は設定電圧Ｏに対応する超音波モータの始動時の
駆動周波数であり、P1は動作設定値で、位相比較器15に
よりP0−P1に比例した電圧O1が出力される。電圧O1は設
定電圧Ｏと加算器８により加算され電圧制御発振器７の
制御端子C1に入力される。この時、P0−P1が正なら駆動
周波数を下げ、P0−P1が負なら駆動周波数を上げれば、
位相差がP1になるように制御できる。従って、P1に対す
る周波数f1での電流値i1で振動体を駆動する。駆動周波
数が一定ならば、温度や負荷の変化により振動体の特性
が同図の点線のように変化すれば、圧電体へ流入する電
流値はi2となり、超音波モータの速度が大きく変化す
る。しかし、第１図に示した駆動回路によれば、駆動時
での位相差をP1近傍にするように制御が働くので、駆動
周波数はf2に変化し、その時の電流値はi3となり電流値
の変化を小さくできる。従って、超音波モータの特性は
温度や負荷に対して安定である。FIG. 2 shows the frequency characteristics of the current flowing into the piezoelectric body and the phase difference between the drive voltage and the current for explaining the specific circuit of FIG. In the figure, the solid line represents the characteristics of the ultrasonic motor during one operation, and the dotted line represents the characteristics during another operation. f 0 is a drive frequency at the start of the ultrasonic motor corresponding to the set voltage O, P 1 is an operation set value, and the phase comparator 15 outputs a voltage O 1 proportional to P 0 −P 1 . The voltage O 1 is added to the set voltage O by the adder 8 and input to the control terminal C 1 of the voltage controlled oscillator 7. At this time, if P 0 −P 1 is positive, the drive frequency is reduced, and if P 0 −P 1 is negative, the drive frequency is increased,
It can be controlled so that the phase difference becomes P 1. Therefore, to drive the vibrator at a current value i 1 at frequency f 1 for P 1. If the driving frequency is constant, if the change to the characteristics of the vibrator are dotted in the figure by a change in temperature or load, current flowing into the piezoelectric body i 2, and the speed of the ultrasonic motor changes greatly . However, according to the driving circuit shown in FIG. 1, since the phase difference at the time of driving acts controlled to P 1 near the drive frequency changes to f 2, the current value at that time i 3 next Changes in the current value can be reduced. Therefore, the characteristics of the ultrasonic motor are stable with respect to temperature and load.
しかし、超音波モータの起動時に大きな負荷がかかる
と、振動体の特性は第３図の点線で示したようになる。
これは、負荷が大きくなることにより、前記と同じ駆動
電圧では振動体に移動体を駆動するに充分な進行波が励
振できないことに起因する。従って、駆動周波数f0で始
動し、前記と同様な制御をかけると、位相差P3とP1の差
は常に正となり駆動周波数は低下して、永久に正常な動
作点を見付けられず、超音波モータは起動できない。故
に、駆動電圧と電流の位相差が、第２の設定値P2以上に
なったことを位相比較器16で検出したら、つまり駆動周
波数が同図の周波数f3以下になったら、位相比較器16の
出力を受けて制御器17はスイッチ18を開き、駆動周波数
を初期値f0にもどし、電力増幅器10と11の制御端子C2と
C3により、瞬時、駆動電圧の振幅値あるいは駆動電圧の
パルス幅を大きくする。すると、振動体に充分に移動体
を駆動できるだけの振幅値の進行波が励振される。する
と、移動体は進行波に持ち上げられ、振動体への負荷は
小さくなり、その共振特性は同図中の実線で示した通常
の動作時の特性に戻る。ここで、制御器17はスイッチ18
を閉じ、電力増幅器10と11の出力をもとにもどし通常時
の制御を行う。However, when a large load is applied at the time of starting the ultrasonic motor, the characteristics of the vibrator become as shown by the dotted line in FIG.
This is because, due to an increase in load, a traveling wave that is sufficient to drive the moving body cannot be excited by the vibrating body at the same driving voltage as described above. Therefore, when starting at the drive frequency f 0 and performing the same control as above, the difference between the phase differences P 3 and P 1 is always positive, the drive frequency is reduced, and a normal operating point cannot be found forever, Ultrasonic motor cannot start. Thus, the phase difference between the drive voltage and current, when it became the second set value P 2 or more is detected by the phase comparator 16, i.e. When the driving frequency is equal to or less than the frequency f 3 of the drawing, a phase comparator the controller 17 receives the output of the 16 opens switch 18, the drive frequency back to the initial value f 0, and the control terminal C 2 of the power amplifier 10 and 11
The C 3, instantaneously, the pulse width of the amplitude value or the drive voltage of the drive voltage is increased. Then, a traveling wave having an amplitude value enough to drive the moving body is sufficiently excited by the vibrating body. Then, the moving body is lifted by the traveling wave, the load on the vibrating body is reduced, and the resonance characteristic returns to the characteristic at the time of normal operation shown by the solid line in FIG. Here, the controller 17 is a switch 18
Is closed, and the output of the power amplifiers 10 and 11 is returned to the original state to perform the normal control.
第４図は超音波モータの起動時に負荷が大きくなり、
時間t1だけ駆動電圧のパルス幅を大きくしたときのタイ
ミング図である。D1とD2は通常時の駆動波形で、D3とD4
はパルス幅を大きくしたときの駆動波形である。第５図
は超音波モータの起動時に負荷が大きくなり、時間t2だ
け駆動電圧の振幅値を大きくしたときのタイミング図で
ある。D5とD6は通常時の駆動波形で、D7とD8は振幅値を
大きくしたときの駆動波形である。FIG. 4 shows that the load increases when the ultrasonic motor is started,
Is a timing diagram when the large pulse width of the time t 1 by the driving voltage. D 1 and D 2 in the normal driving waveform, D 3 and D 4
Is a drive waveform when the pulse width is increased. Figure 5 is loaded at the start of the ultrasonic motor is increased, a timing diagram when the large amplitude of the drive voltage by a time t 2. D 5 and D 6 in normal driving waveform, D 7 and D 8 is a drive waveform when a larger amplitude values.
超音波モータの起動を安定にするために起動時に、い
つも瞬時的に駆動電圧のパルス幅を大きくしたり、振幅
値を大きくすれば、負荷が大きくないときには、移動体
が大きな速度で回転したり、場合によっては、過大な電
流が流れて振動体を破損する。本発明のように圧電体に
印加する電圧と圧電体へ流入する電流の位相差が設定値
P2よりも大きくなった時のみに、必要に応じて駆動電圧
を大きくすれば過大な電流が流れるのを防止できる。To stabilize the starting of the ultrasonic motor, always increase the pulse width of the drive voltage instantaneously at startup, or increase the amplitude value.If the load is not large, the moving body will rotate at a high speed. In some cases, an excessive current flows to damage the vibrating body. As in the present invention, the phase difference between the voltage applied to the piezoelectric body and the current flowing into the piezoelectric body is a set value.
Only when it becomes greater than P 2, it is possible to prevent the excessive current from flowing by increasing the driving voltage if necessary.
本実施例の駆動回路によれば、温度や負荷が変動して
も、常に安定な起動と通常動作をする超音波モータを提
供できる。According to the drive circuit of this embodiment, it is possible to provide an ultrasonic motor that always performs stable startup and normal operation even when the temperature or the load changes.
発明の効果 本発明によれば、温度や負荷が変動しても、常に安定
な起動と通常動作をする超音波モータを提供できる。Effects of the Invention According to the present invention, it is possible to provide an ultrasonic motor that always performs stable startup and normal operation even when the temperature or the load changes.
第１図は本発明の超音波モータの駆動方法を実現する具
体回路のブロック図、第２図は通常動作時の駆動電流、
電圧と電流の位相差周波数特性図、第３図は大きな負荷
がかかった時の振動体の駆動電流、電圧と電流の位相差
周波数特性図、第４図は駆動電圧のパルス幅を瞬時大き
くした時の駆動電圧のタイミング図、第５図は駆動電圧
の振幅値を瞬時大きくした時の駆動電圧のタイミング
図、第６図は円環形超音波モータの切り欠き斜視図、第
７図は第６図の超音波モータに用いた圧電体の形状と電
極構造を示す平面図、第８図は超音波モータの動作原理
の説明図である。 ７……電圧制御発振器、８……加算器、９……90度移相
器、10、11……電力増幅器、12……電圧検出器、13……
電流検出器、14……位相差検出器、15、16……位相比較
器、17……制御器、18……スイッチ。FIG. 1 is a block diagram of a specific circuit for realizing a driving method of an ultrasonic motor according to the present invention, and FIG. 2 is a driving current in a normal operation.
FIG. 3 shows the driving current of the vibrating body when a large load is applied, FIG. 3 shows the phase difference frequency characteristics of the voltage and current, and FIG. 4 shows the pulse width of the driving voltage instantaneously increased. FIG. 5 is a timing diagram of the drive voltage when the amplitude value of the drive voltage is instantaneously increased, FIG. 6 is a cutaway perspective view of the annular ultrasonic motor, and FIG. FIG. 8 is a plan view showing the shape and electrode structure of a piezoelectric body used in the ultrasonic motor shown in FIG. 8, and FIG. 8 is an explanatory diagram of the operation principle of the ultrasonic motor. 7 ... voltage controlled oscillator, 8 ... adder, 9 ... 90 degree phase shifter, 10, 11 ... power amplifier, 12 ... voltage detector, 13 ...
Current detector, 14 ... Phase difference detector, 15, 16 ... Phase comparator, 17 ... Controller, 18 ... Switch.
Claims (1)
電体と弾性体とから構成される振動体に弾性進行波を励
振することにより、前記振動体に接触して設置された移
動体を移動させる超音波モータであって、 前記超音波モータの特性に従って前記圧電体を駆動する
駆動電圧の振幅値あるいはパルス幅を駆動開始前に設定
し、前記交流駆動電圧と前記圧電体に流入する電流の位
相差を制御パラメータとし、 動作点として第１の位相差を、前記第１の位相差よりも
大きな値に第２の位相差を設定し、 起動時に前記第１の位相差と前記第２の位相差の間の値
の位相差に相当する周波数の前記交流駆動電圧で駆動を
開始し、前記圧電体の前記交流駆動電圧と前記圧電体へ
流入する電流の動作位相差と前記第１の位相差との差に
より前記交流駆動電圧の周波数を制御して、前記動作位
相差が前記第１の位相差の近傍になるように制御し、 および、起動時に前記第１の位相差と前記第２の位相差
の間の値の位相差に相当する周波数の前記交流駆動電圧
で駆動を開始して、前記動作位相差が前記第１の位相差
の近傍になるように制御して、前記動作位相差が、前記
第２の位相差以上になった時には、前記交流駆動電圧の
振幅値あるいはパルス幅を前記設定値よりも大きくした
後に再び前記の起動動作を開始し、一定時間後に前記交
流駆動電圧の振幅値あるいはパルス幅を前記設定値に戻
して、前記動作位相差と前記第１の位相差との差により
前記交流駆動電圧の周波数を制御して、前記動作位相差
が前記第１の位相差の近傍になるように制御することを
特徴とする超音波モータの駆動方法。1. A moving device installed in contact with a vibrating body by driving a piezoelectric body with an AC driving voltage to excite a vibrating body composed of the piezoelectric body and an elastic body with an elastic traveling wave. An ultrasonic motor for moving a body, wherein an amplitude value or a pulse width of a drive voltage for driving the piezoelectric body is set according to characteristics of the ultrasonic motor before starting driving, and the AC drive voltage and the piezoelectric material flow into the piezoelectric body. The first phase difference is set as an operating point and the second phase difference is set to a value larger than the first phase difference, and the first phase difference and the first phase difference are set at the time of startup. The drive is started with the AC drive voltage having a frequency corresponding to the phase difference of the value between the second phase differences, and the AC drive voltage of the piezoelectric body and the operating phase difference between the current flowing into the piezoelectric body and the 1 and the AC drive power , So that the operating phase difference is close to the first phase difference, and the order of the value between the first phase difference and the second phase difference at startup. Driving is started with the AC drive voltage having a frequency corresponding to the phase difference, and the operation phase difference is controlled to be close to the first phase difference, so that the operation phase difference becomes the second phase difference. When the above is reached, the starting operation is started again after the amplitude value or the pulse width of the AC drive voltage is made larger than the set value, and the amplitude value or the pulse width of the AC drive voltage is set after a predetermined time. Returning to the value, the frequency of the AC drive voltage is controlled by the difference between the operation phase difference and the first phase difference, and the operation phase difference is controlled so as to be close to the first phase difference. A method for driving an ultrasonic motor, comprising:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62102258A JP2574293B2 (en) | 1987-04-24 | 1987-04-24 | Ultrasonic motor driving method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62102258A JP2574293B2 (en) | 1987-04-24 | 1987-04-24 | Ultrasonic motor driving method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63268474A JPS63268474A (en) | 1988-11-07 |
| JP2574293B2 true JP2574293B2 (en) | 1997-01-22 |
Family
ID=14322564
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62102258A Expired - Fee Related JP2574293B2 (en) | 1987-04-24 | 1987-04-24 | Ultrasonic motor driving method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2574293B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3925459A1 (en) * | 1989-08-01 | 1991-02-14 | Ferton Holding | ULTRASONIC GENERATOR WITH A PIEZOELECTRIC CONVERTER |
| EP1441398A1 (en) * | 2003-01-27 | 2004-07-28 | Koninklijke Philips Electronics N.V. | Piezoelectric drive system and control method for a piezoelectric drive system |
| JP5791343B2 (en) | 2010-05-31 | 2015-10-07 | キヤノン株式会社 | Vibration type motor control method and vibration type motor drive device |
-
1987
- 1987-04-24 JP JP62102258A patent/JP2574293B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63268474A (en) | 1988-11-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR900007413B1 (en) | Drive method for ultrasonic motor | |
| JPH0528072B2 (en) | ||
| JP2574293B2 (en) | Ultrasonic motor driving method | |
| JP2663380B2 (en) | Piezoelectric ultrasonic linear motor | |
| JPS622869A (en) | Supersonic motor drive device | |
| JP2583904B2 (en) | Ultrasonic motor driving method | |
| JPH09163765A (en) | Driving method and driving circuit of ultrasonic motor | |
| JP2548248B2 (en) | Ultrasonic motor controller | |
| JPH072022B2 (en) | Ultrasonic motor driving method | |
| JP2506895B2 (en) | Ultrasonic motor controller | |
| JP2636280B2 (en) | Driving method of ultrasonic motor | |
| JPH04322179A (en) | Method of driving ultrasonic motor | |
| JP2558709B2 (en) | Ultrasonic motor drive | |
| JP3260041B2 (en) | Ultrasonic motor driving method and driving circuit | |
| JPH01136575A (en) | Supersonic motor driving device | |
| JPS6292782A (en) | Ultrasonic motor device | |
| JP2563351B2 (en) | Ultrasonic motor driving method | |
| JPS6356179A (en) | Driving of ultrasonic motor | |
| JPH01298967A (en) | Driver for ultrasonic actuator | |
| JPH0746910B2 (en) | Ultrasonic motor driving method | |
| JP2506896B2 (en) | Ultrasonic motor drive | |
| JPS63299788A (en) | Ultrasonic motor driving device | |
| JPH0632569B2 (en) | Ultrasonic motor driving method | |
| JPS6292781A (en) | Ultrasonic motor device | |
| JPS61124274A (en) | Supersonic wave motor apparatus |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |