JP2995665B2 - Ultrasonic motor - Google Patents
Ultrasonic motorInfo
- Publication number
- JP2995665B2 JP2995665B2 JP2262986A JP26298690A JP2995665B2 JP 2995665 B2 JP2995665 B2 JP 2995665B2 JP 2262986 A JP2262986 A JP 2262986A JP 26298690 A JP26298690 A JP 26298690A JP 2995665 B2 JP2995665 B2 JP 2995665B2
- Authority
- JP
- Japan
- Prior art keywords
- piezoelectric
- torsional
- ultrasonic motor
- vibrator
- vibration
- 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
- 230000010287 polarization Effects 0.000 claims description 12
- 239000000919 ceramic Substances 0.000 claims description 10
- 230000002093 peripheral effect Effects 0.000 claims description 4
- 238000006073 displacement reaction Methods 0.000 description 10
- 238000000034 method Methods 0.000 description 4
- 230000008602 contraction Effects 0.000 description 3
- 239000002131 composite material Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
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OA機器や玩具などに用いられる小型モータに
関し，特にローター直径の小さい小型の超音波モータに
関するものである。Description: TECHNICAL FIELD The present invention relates to a small motor used for office automation equipment and toys, and more particularly to a small ultrasonic motor having a small rotor diameter.
（従来の技術） 超音波モータは従来の電磁モータと比較して，低回転
で高いトルクが得られること，停止保持力を有するこ
と，電磁ノイズが小さいことなどの特徴を有しており，
カメラのオートフォーカス用や自動車用パワーモータな
どに使用されている。第４図は従来の超音波モータの構
造例を示す概略図である。この例において，圧電捩り振
動子51と圧電縦振動子52を含む縦−捩り複合振動子53を
一方の端部に設けられた軸56に回転自在に支持されたロ
ーター54を圧接して構成している。(Prior art) Ultrasonic motors have the characteristics of being able to obtain high torque at low rotation speed, having a stop holding force, and having low electromagnetic noise, compared to conventional electromagnetic motors.
It is used for autofocus of cameras and power motors for automobiles. FIG. 4 is a schematic view showing a structural example of a conventional ultrasonic motor. In this example, a longitudinal-torsional composite vibrator 53 including a piezoelectric torsional vibrator 51 and a piezoelectric longitudinal vibrator 52 is constructed by pressing a rotor 54 rotatably supported by a shaft 56 provided at one end. ing.
第５図は従来の縦−捩り型超音波モータに用いられて
いる圧電捩り振動子51の構造を示す斜視図である。この
例において，弦の方向に分極された複数個の扇形の圧電
セラミック板55が円板あるいは円環状に，矢印で示され
る各々の分極の向きが閉じるように端面を合わせて接合
されている。FIG. 5 is a perspective view showing the structure of a piezoelectric torsional vibrator 51 used in a conventional longitudinal-twist type ultrasonic motor. In this example, a plurality of sector-shaped piezoelectric ceramic plates 55 polarized in the direction of a chord are joined in a disk or ring shape with their end faces aligned so that the directions of polarization indicated by arrows are closed.
第６図（ａ），（ｂ）は第４図の縦−捩り型超音波モ
ータの動作原理の説明図である。これらの図において，
縦−捩り複合振動子53の長さを横軸とした円周方向の捩
り変位と長さ方向の伸縮変位の状態が夫々示されてい
る。各々の変位の向きは第６図（ａ）に示されるよう
に，捩り変位においては，圧電縦−捩り振動子の一端が
右回りとなると他端はその逆の左回りとなり，その変位
の大きさは，振動の中心から離れるに従って大きくな
る。6 (a) and 6 (b) are explanatory diagrams of the operation principle of the longitudinal-twist type ultrasonic motor of FIG. In these figures,
The state of the torsional displacement in the circumferential direction with the length of the longitudinal-torsional composite vibrator 53 as the horizontal axis and the state of the expansion and contraction displacement in the length direction are shown, respectively. As shown in FIG. 6 (a), the direction of each displacement is such that in a torsional displacement, when one end of the piezoelectric longitudinal-torsional vibrator is clockwise, the other end is counterclockwise, and the magnitude of the displacement is large. The magnitude increases as the distance from the center of the vibration increases.
一方，第６図（ｂ）中に示すように，長さ方向の伸び
変位は，中心から一定で，さらに離れるに従って次第に
大きくなる。On the other hand, as shown in FIG. 6 (b), the elongation displacement in the length direction is constant from the center, and gradually increases as the distance from the center increases.
（発明が解決しようとする課題） 第５図からわかるように従来の圧電捩り振動子51は，
扇形の圧電セラミック板55をその端面を合わせて複数個
接着して構成しているため，組立工程が複雑になる上に
接着による特性のばらつきが大きいという欠点がある。
また，一般に円筒を含む円柱状の振動子においては，捩
り振動の共振周波数と縦振動の共振周波数が一致しない
ため，捩り振動の共振周波数で駆動し，縦振動は非共振
の状態で駆動されることになる。従って，縦振動の振動
振幅が小さくなり超音波モータのトルクを大きくするこ
とが難しいという欠点がある。(Problems to be Solved by the Invention) As can be seen from FIG. 5, the conventional piezoelectric torsional vibrator 51
Since a plurality of fan-shaped piezoelectric ceramic plates 55 are bonded together with their end faces aligned, there are drawbacks in that the assembling process becomes complicated and that the characteristics due to bonding vary greatly.
In general, a cylindrical vibrator including a cylinder is driven at the torsional vibration resonance frequency because the resonance frequency of the torsional vibration does not match the resonance frequency of the longitudinal vibration, and the longitudinal vibration is driven in a non-resonant state. Will be. Therefore, there is a disadvantage that the vibration amplitude of the longitudinal vibration becomes small and it is difficult to increase the torque of the ultrasonic motor.
そこで，本発明の技術的課題はローターの直径を小さ
くした小型で，特性が一定しており，且つトルクの大き
い超音波モータを提供することにある。Therefore, a technical problem of the present invention is to provide an ultrasonic motor having a small rotor with a small diameter, constant characteristics, and a large torque.
また，本発明の別の技術的課題は構成部品の少なく，
製造が容易で製造コストが低く，安価な超音波モータを
提供することにある。Another technical problem of the present invention is that the number of components is small.
An object of the present invention is to provide an inexpensive ultrasonic motor which is easy to manufacture, has low manufacturing costs, and is inexpensive.
（課題を解決するための手段） 本発明によれば，圧電セラミク中空円柱の外周面の長
さ方向と45゜の方向に交差指電極を形成し，該交差指電
極を用いて分極及び駆動を行い，前記中空円柱に捩り振
動を励振可能とし，前記圧電セラミック中空円柱捩り振
動子の一側端部を前記捩り振動子よりも質量の大きな圧
電積層アクチュエータに固定し，前記捩り振動子のもう
一方の端部に回転自在に支持されたローターを圧接して
構成したことを特徴とする超音波モータが得られる。(Means for Solving the Problems) According to the present invention, an interdigital electrode is formed in a direction of 45 ° with respect to the length direction of the outer peripheral surface of a hollow cylindrical piezoelectric ceramic, and polarization and driving are performed using the interdigital electrode. Then, torsional vibration can be excited in the hollow cylinder, one end of the piezoelectric ceramic hollow cylindrical torsional vibrator is fixed to a piezoelectric laminated actuator having a larger mass than the torsional vibrator, and the other end of the torsional vibrator is fixed. An ultrasonic motor characterized in that a rotor rotatably supported at the end of the motor is pressed against the end of the motor.
（作 用） 本発明においては，捩り振動子の一端面と，圧電アク
チュエータの一端面とが接合されている。(Operation) In the present invention, one end face of the torsional vibrator and one end face of the piezoelectric actuator are joined.
圧電積層アクチュエータは軸方向に伸縮振動を行う。
捩り振動子は周方向に捩り振動を行う。The piezoelectric laminated actuator performs stretching vibration in the axial direction.
The torsional vibrator performs torsional vibration in the circumferential direction.
圧電積層アクチュエータと捩り振動子との共振周波数
を一致させることで，捩り振動の他端に圧接されたロー
タは予め定められた軸回りに回転する。By matching the resonance frequencies of the piezoelectric laminated actuator and the torsional vibrator, the rotor pressed against the other end of the torsional vibration rotates around a predetermined axis.
（実施例） 以下本発明の超音波モータについて図面を用いて詳し
く説明する。(Example) Hereinafter, an ultrasonic motor of the present invention will be described in detail with reference to the drawings.
第１図は本発明の縦−捩り型超音波モータの一構成例
を示す斜視図である。この例において，超音波モータ１
は圧電セラミック中空円柱の捩り振動子７の一端部を圧
電積層アクチュエータ９の一端面に固定し，回転自在に
支持されたローター10を前記捩り振動子７のもう一方の
端面に圧接して構成されている。FIG. 1 is a perspective view showing a configuration example of a longitudinal-twist type ultrasonic motor of the present invention. In this example, the ultrasonic motor 1
Is constituted by fixing one end of a torsional vibrator 7 of a piezoelectric ceramic hollow column to one end of a piezoelectric laminated actuator 9 and pressing a rotatably supported rotor 10 against the other end of the torsional vibrator 7. ing.
第２図は第１図の超音波モータに用いられる圧電捩り
振動子７の構造例を示す概略図である。この例におい
て，プレス成形された圧電セラミック中空円柱の外周面
の長さ方向と45゜の方向に延在するように導電ペースト
を印刷することにより指電極6a,6bが形成され，さらに
これらの指電極6a,6bを一つおきに互いに反対の端部を
共通電極6c,6dに接続して交差指電極６が形成された二
端子とされてる。この交差指電極６を用いて分極処理を
施すと分極方向は交差指電極の各指電極6a,6bの長さ方
向と直角な方向となる。この状態で前記交差指電極６に
共通電極6c,6dから交流電圧を印加すると，電圧の極性
が分極時の電圧の極性と同じ場合は分極の方向の伸び歪
が発生し，電圧の極性が分極時の極性と逆の場合は分極
の方向に縮み歪が発生する。分極方向に伸びあるいは縮
み歪が発生した場合，分極方向と直角な方向にはこれら
と反対に縮みあるいは伸び歪が発生する。以上の結果と
して前記圧電セラミック中空円柱８に捩り変位が発生す
る。FIG. 2 is a schematic diagram showing a structural example of the piezoelectric torsional vibrator 7 used in the ultrasonic motor of FIG. In this example, finger electrodes 6a and 6b are formed by printing a conductive paste so as to extend in the direction of 45 ° with respect to the length direction of the outer peripheral surface of the pressed-formed piezoelectric ceramic hollow cylinder. Every other electrode 6a, 6b is connected to the common electrode 6c, 6d at the opposite end to form two terminals on which the interdigital electrode 6 is formed. When the polarization process is performed using the interdigital electrode 6, the polarization direction is perpendicular to the length direction of each of the finger electrodes 6a and 6b of the interdigital electrode. When an AC voltage is applied to the interdigital electrode 6 from the common electrodes 6c and 6d in this state, if the polarity of the voltage is the same as the polarity of the voltage at the time of polarization, extension strain occurs in the direction of the polarization, and the polarity of the voltage is changed. If the polarity is opposite to the polarity at the time, shrinkage strain occurs in the direction of polarization. When elongation or contraction occurs in the polarization direction, contraction or elongation occurs in the direction perpendicular to the polarization direction. As a result, torsional displacement occurs in the piezoelectric ceramic hollow cylinder 8.
また，第３図は第１図の超音波モータに用いられる圧
電積層アクチュエータ９の概略図である。この場合，時
定数の関係上振動子の静電容量は予め小さく設計してあ
る。この圧電積層アクチュエータ９には予め長さ方向に
分極処理が施してある。この状態で前記圧電積層アクチ
ュエータ９に直流電圧を印加すると，駆動電圧の極性が
分極時の極性と一致し，分極の方向に伸び歪が発生す
る。以上の結果として前記圧電積層アクチュエータ９に
白抜きの矢印５で示すような縦変位が発生する。FIG. 3 is a schematic view of a piezoelectric laminated actuator 9 used in the ultrasonic motor of FIG. In this case, the capacitance of the vibrator is designed to be small in advance due to the time constant. The piezoelectric laminated actuator 9 is preliminarily polarized in the longitudinal direction. When a DC voltage is applied to the piezoelectric laminated actuator 9 in this state, the polarity of the drive voltage matches the polarity at the time of polarization, and an elongation strain occurs in the direction of polarization. As a result, a vertical displacement as shown by a white arrow 5 occurs in the piezoelectric laminated actuator 9.
第１図に戻って，超音波モータ１の圧電セラミック中
空円柱に捩り振動の変位と同期して縦振動が励振される
と，ローター10は捩り変位の方向に回転する。この場合
の回転数及びトルクは駆動周波数が一定の場合，圧電捩
り振動子による捩り振動及び圧電積層アクチュエータに
よる縦振動の振動振幅の大きさによって定まる。Returning to FIG. 1, when the longitudinal vibration is excited in the piezoelectric ceramic hollow cylinder of the ultrasonic motor 1 in synchronization with the displacement of the torsional vibration, the rotor 10 rotates in the direction of the torsional displacement. In this case, when the driving frequency is constant, the rotation speed and the torque are determined by the magnitude of the vibration amplitude of the torsional vibration by the piezoelectric torsional vibrator and the longitudinal vibration by the piezoelectric laminated actuator.
本発明の実施例に係る超音波モータにおいては，圧電
積層アクチュエー９を用いており，低電圧で大きな縦振
幅を得ることが出来る。また，前記捩り振動子７は形状
が薄肉パイプ状であるのに対して前記積層アクチュエー
タの形状は円柱状あるいは角柱状であるので単位長さ当
りの質量が１桁程度大きいため，前記捩り振動子は前記
圧電積層アクチュエータをベースに片側固定型の振動を
行う。従って，捩り振動子７の捩り振動の振動振幅と圧
電積層アクチュエータ９の縦振動の振動振幅を共に大き
くすることが可能となる。この時の駆動電圧の周波数は
捩り振動の共振周波数に合わせてあり，前記圧電積層ア
クチュエータ９の駆動電圧の周波数は，この周波数に合
わせてあり，それぞれの駆動電圧の位相は90゜である。
また，捩り振動子の端面に圧接されるローター10の回転
方向は捩り振動駆動電圧と縦振動駆動電圧の位相の何れ
かを一方を180゜変化させることにより可能である。In the ultrasonic motor according to the embodiment of the present invention, the piezoelectric laminated actuator 9 is used, and a large longitudinal amplitude can be obtained at a low voltage. The torsional vibrator 7 has a thin pipe shape, whereas the laminated actuator has a cylindrical or prismatic shape. Therefore, the mass per unit length is about one order of magnitude larger. Performs one-side fixed vibration based on the piezoelectric laminated actuator. Therefore, both the vibration amplitude of the torsional vibration of the torsional vibrator 7 and the vibration amplitude of the longitudinal vibration of the piezoelectric laminated actuator 9 can be increased. The frequency of the drive voltage at this time is adjusted to the resonance frequency of the torsional vibration, and the frequency of the drive voltage of the piezoelectric laminated actuator 9 is adjusted to this frequency, and the phase of each drive voltage is 90 °.
The rotation direction of the rotor 10 pressed against the end face of the torsional vibrator can be changed by changing one of the phases of the torsional vibration drive voltage and the longitudinal vibration drive voltage by 180 °.
（発明の効果） 以上説明したように本発明の超音波モータにおいて
は，駆動力を発生させるための圧電捩り振動子の形状が
単純で，通常一般的に適用されているプレス成形技術に
より容易に製造することが可能な圧電セラミック中空円
柱を用いて，この外周面にこれも一般的な技術である電
極印刷を施すことにより圧電捩り振動子が得られるた
め，製造が容易で複雑な加工工程による特性のばらつき
の少ない超音波モータが得られる。(Effects of the Invention) As described above, in the ultrasonic motor of the present invention, the shape of the piezoelectric torsional vibrator for generating the driving force is simple, and it can be easily formed by the generally used press molding technique. A piezoelectric torsional vibrator can be obtained by using a piezoceramic hollow cylinder that can be manufactured, and by applying electrode printing, which is also a common technique, to the outer peripheral surface of the hollow column. An ultrasonic motor with less variation in characteristics can be obtained.
更に，本発明の超音波モータにおいては，縦振動を得
るために圧電積層アクチュエータを用いており，低電圧
で大きな縦振幅を得ることが出来る。従って，トルクが
大きく小径で小型の超音波モータが得られる。Furthermore, in the ultrasonic motor of the present invention, a piezoelectric laminated actuator is used to obtain longitudinal vibration, and a large longitudinal amplitude can be obtained at a low voltage. Accordingly, a small ultrasonic motor having a large torque and a small diameter can be obtained.
第１図は本発明の超音波モータの一構成例を示す斜視
図，第２図は第１図の超音波モータに用いられる圧電捩
り振動子の構造を示す概略図，第３図は第１図の超音波
モータに用いられる圧電積層アクチュエータ９の概略
図，第４図は従来の超音波モータの一構造例を示す斜視
図，第５図は第４図の超音波モータに用いられる圧電捩
り振動子５の構造を示す斜視図，第６図は縦−捩り型超
音波モータの動作原理の説明図である。 図中,1は超音波モータ,5は縦振動の方向を示す矢印,6は
交差指電極,7は圧電捩り振動子,9は圧電積層アクチュエ
ータ,10はロータ,51は圧電捩り振動子,52は圧電縦振動
子,53は超音波モータ,54はロータ,56は軸。FIG. 1 is a perspective view showing an example of the configuration of the ultrasonic motor of the present invention, FIG. 2 is a schematic view showing the structure of a piezoelectric torsional vibrator used in the ultrasonic motor of FIG. 1, and FIG. FIG. 4 is a schematic view of a piezoelectric laminated actuator 9 used in the ultrasonic motor shown in FIG. 4, FIG. 4 is a perspective view showing one structural example of a conventional ultrasonic motor, and FIG. 5 is a piezoelectric torsion used in the ultrasonic motor shown in FIG. FIG. 6 is a perspective view showing the structure of the vibrator 5, and FIG. 6 is an explanatory view of the operation principle of the longitudinal-twist type ultrasonic motor. In the figure, 1 is an ultrasonic motor, 5 is an arrow indicating the direction of longitudinal vibration, 6 is an interdigital electrode, 7 is a piezoelectric torsional vibrator, 9 is a piezoelectric laminated actuator, 10 is a rotor, 51 is a piezoelectric torsional vibrator, 52 Is a piezoelectric longitudinal oscillator, 53 is an ultrasonic motor, 54 is a rotor, and 56 is a shaft.
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.6，ＤＢ名) H02N 2/00 ──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. 6 , DB name) H02N 2/00
Claims (1)
向と45゜の方向に交差指電極を形成し、該交差指電極を
用いて分極及び駆動を行い、前記中空円柱に捩り振動を
励振可能とし、前記圧電セラミック中空円柱捩り振動子
の一側端部を前記捩り振動子よりも質量の大きな圧電積
層アクチュエータに固定し、前記捩り振動子のもう一方
の端部に回転自在に支持されたロータを圧接して構成し
たことを特徴とする超音波モータ。An interdigital electrode is formed in a direction of 45.degree. With respect to the length direction of the outer peripheral surface of a piezoelectric ceramic hollow cylinder, and polarization and driving are performed using the interdigital electrode to excite torsional vibration in the hollow cylinder. One end of the piezoelectric ceramic hollow cylindrical torsional vibrator was fixed to a piezoelectric laminated actuator having a larger mass than the torsional vibrator, and was rotatably supported by the other end of the torsional vibrator. An ultrasonic motor comprising a rotor press-contacted.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2262986A JP2995665B2 (en) | 1990-10-02 | 1990-10-02 | Ultrasonic motor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2262986A JP2995665B2 (en) | 1990-10-02 | 1990-10-02 | Ultrasonic motor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04145871A JPH04145871A (en) | 1992-05-19 |
| JP2995665B2 true JP2995665B2 (en) | 1999-12-27 |
Family
ID=17383312
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2262986A Expired - Fee Related JP2995665B2 (en) | 1990-10-02 | 1990-10-02 | Ultrasonic motor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2995665B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10312830B2 (en) | 2015-08-19 | 2019-06-04 | Lawrence Livermore National Security, Llc | Electrostatic generator/motor rotor electrode system suitable for installation on the outer surface of an EMB rotor |
-
1990
- 1990-10-02 JP JP2262986A patent/JP2995665B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04145871A (en) | 1992-05-19 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |