JPH07274553A - Ultrasonic actuator - Google Patents

Abstract

PURPOSE:To improve performance such as driving force, driving speed, etc., by generating an elliptic motion consisting of a driving component and a vertical component to the driving direction of the driving component in the driving section of an elastic body in a main electromechanical transducer and generating a motion in the driving component in auxiliary electromechanical transducers. CONSTITUTION:Main piezoelectric bodies 12, 13 are used as electromechanical transducers for generating a longitudinal vibration mode and a flexural vibration mode, voltage at a terminal A is applied to the main piezoelectric body 12, and voltage at a terminal B is applied to the main piezoelectric body 13. Auxiliary piezoelectric bodies 12R, 13R and auxiliary piezoelectric bodies 12L, 13L are polarized in the thickness diirection, and the direction of polarization is directed in the same direction as the main piezoelectric body 12 to joint surfaces in the auxiliary piezoelectric bodies 12R, 12L, and directed in the same direction as the main piezoelectric body 13 to joint surfaces in the auxiliary piezoelectric bodies 13R, 13L. Accordingly, an elliptic motion is expanded or contracted in the driving direction, thus increasing or reducing driving force, then controlling driving force or driving speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic actuator for generating a driving force by generating an elliptical motion in a rod-shaped elastic body, and more particularly to an ultrasonic actuator which drives a longitudinal vibration mode and a bending vibration mode in two phases. is there.

[0002]

2. Description of the Related Art FIG. 8 is a diagram showing a conventional example of a linear ultrasonic actuator. In the conventional linear ultrasonic actuator, a vibration transformer 102 is arranged at one end of a rod-shaped elastic body 101 and a vibration damper 103 is arranged at the other end. Transducers 102a and 103a are joined to the respective transformers 102 and 103. An alternating voltage is applied from the oscillator 102b to the vibrator 102a for vibration to vibrate the rod-shaped elastic body 101, and this vibration causes the rod-shaped elastic body 101 to vibrate.
To become a traveling wave. The traveling wave drives the moving body 104 that is in pressure contact with the rod-shaped elastic body 101.

On the other hand, the vibration of the rod-shaped elastic body 101 is transmitted to the vibrator 103a through the vibration damping transformer 103, and the vibrator 103a converts the vibration energy into electric energy. The load 103b connected to the vibrator 103a consumes the electric energy to absorb the vibration. This vibration damping transformer 103 suppresses the reflection of the end surface of the rod-shaped elastic body 101, and the rod-shaped elastic body 1
The generation of standing waves of 01 eigenmodes is prevented.

The linear type ultrasonic actuator shown in FIG.
The length of the rod-shaped elastic body 101 is required only for the moving range of the moving body 104, and the whole of the rod-shaped elastic body 101 has to be vibrated, so that the device becomes large and the standing wave of the eigenmode is generated. In order to prevent the generation, the transformer 10 for damping
There was a problem that 3 and so on were required.

In order to solve the above-mentioned problems, various self-propelled ultrasonic actuators have been proposed. For example, the purpose of “222 Optical Pickup Movement in“ 5th Electromagnetic Force-related Dynamics Symposium Proceedings ” The "degenerate vertical L1-bending B4 mode flat plate motor" described in "Piezoelectric linear motor" is known.

FIG. 9 is a schematic view showing a conventional example of a modified degenerate vertical L1-bending B4 mode flat plate motor.
9A is a front view, FIG. 9B is a side view, and FIG. 9C is a plan view. The elastic body 1 includes a rectangular flat plate-shaped base portion 1a,
Protrusions 1b, 1 formed on one surface of the base 1a
and c. The piezoelectric bodies 2 and 3 are elements attached to the other surface of the base portion 1a of the elastic body 1 to generate a longitudinal vibration L1 mode and a bending vibration B4 mode. Elastic body 1
The protrusions 1b and 1c are provided at antinodes of the bending vibration B4 mode generated in the base portion 1a, and are pressed against a relative motion member (not shown).

This ultrasonic actuator includes a piezoelectric body 2,
When 3 is excited, longitudinal vibration and bending vibration are generated in the elastic body 1, respectively. Then, when the natural frequencies of the longitudinal vibration and the bending vibration are substantially equal to each other, an elliptic motion is generated on the driving surface of the elastic body 1 due to a combination (degeneration) of the longitudinal vibration and the bending vibration, and a driving force can be obtained. it can. The arrangement of the piezoelectric bodies 2 and 3 is the same as the arrangement of the conventional traveling wave type ultrasonic motor, and it is advantageous to generate bending vibration rather than longitudinal vibration.

[0008]

In the actuator (FIG. 9) using the above-described degenerate mode odd-shaped oscillator, the longitudinal vibration and the bending vibration generated in the elastic body are combined to obtain the driving force on the driving surface. This is the driving principle, and the driving direction component of the elliptical motion generated on the driving surface is formed by longitudinal vibration,
The component perpendicular to the driving direction is formed by bending vibration.

In this case, in order to obtain a large driving force, it is necessary to increase the driving direction component of the elliptic motion.
Therefore, in the above-described conventional driving method, since the flexural vibration may have a larger amplitude than the longitudinal vibration, in order to increase the driving force, the driving direction component of the elliptical motion may be arbitrarily changed as necessary. There was a problem that it could not be increased to the value.

On the other hand, when varying the driving speed or driving force, it is conceivable to control the frequency or voltage amplitude of the driving signal. However, in order to change the frequency, the elastic body 1,
Another problem occurs in the vibrator including the piezoelectric bodies 2 and 3 because the frequency deviates from the most efficient frequency and optimum drive control cannot be performed.

An object of the present invention is to provide an ultrasonic actuator which can solve the above-mentioned problems and improve the performance such as driving force and driving speed.

[0012]

In order to solve the above problems, a first solution means of an ultrasonic actuator according to the present invention is a driving force generation means for generating a main drive signal and a sub drive signal, and the main drive. A main electromechanical conversion element that is excited by a signal, a sub electromechanical conversion element that is excited by the sub driving signal, a first surface, a second surface, and a driving force extracting portion, and the main electromechanical conversion element is An elastic body joined to the first surface and the sub-electromechanical conversion element joined to the second surface;
The main electromechanical conversion element is provided with drive signal switching means that selectively supplies the sub drive signal to the sub electromechanical conversion element while supplying the main drive signal to the main electromechanical conversion element. , An elliptical motion of a driving direction component and a component in a direction perpendicular to the driving direction is generated in the driving force extracting portion of the elastic body, and the sub electromechanical conversion element is driven to the driving force extracting portion of the elastic body. The feature is that the motion of the directional component is generated.

A second solving means is a driving force generating means for generating a main drive signal and a sub drive signal, a main electromechanical conversion element excited by the main drive signal, and a main electromechanical conversion element excited by the sub drive signal. 1st and 2nd auxiliary electromechanical conversion element, and 1st surface, 2nd surface, 3rd surface, and a driving force extraction part, The said main electromechanical conversion element is joined to the said 1st surface, and the said 1st surface And an elastic body having a second sub electromechanical conversion element joined to the second surface and the third surface, and supplying the main drive signal to the main electromechanical conversion element, and to the sub electromechanical conversion element. Drive signal switching means for selectively supplying the sub drive signal, wherein the main electromechanical conversion element includes a drive direction component in the drive force extracting portion of the elastic body and a component in a direction perpendicular to the drive direction. Generating an elliptic motion of Transducer is characterized in that to generate the movement of the drive direction component to the driving force output portion of the elastic body.

A third solving means is the ultrasonic actuator according to the first or second solving means, in which the second elastic body is used.
The surface and / or the third surface are characterized in that they are parallel to the vertical component of the elliptic motion.

A fourth solving means is the ultrasonic actuator according to any one of the first to third solving means, wherein the sub-driving signal has a 180 ° phase difference between the first frequency signal and the first frequency signal. The drive signal switching means is configured to supply the first frequency signal or the second frequency signal to each of the sub electromechanical conversion elements, or switch between three modes without supplying the second frequency signal. It is characterized by performing selectively.

[0016]

According to the present invention, the main electromechanical conversion element is excited by the drive signal to generate longitudinal vibration and bending vibration in the elastic body, and to generate an elliptic motion in the driving force take-out portion. Then, the sub-electromechanical conversion element is excited by the drive signal and mainly causes longitudinal vibration in the elastic body, and increases or decreases the drive direction component of the elliptic motion in the drive force extraction portion.

By providing the sub-electromechanical conversion element on a surface (second surface or third surface) substantially parallel to the amplitude direction of the bending vibration, the sub-electro-mechanical conversion element is perpendicular to the driving direction of the elliptic motion of the driving force extracting portion. It is possible to increase or decrease only the driving direction component of the elliptical motion without generating the bending motion that causes the directional component.

Further, the drive signal to the sub electromechanical conversion element is composed of a first frequency signal and a second frequency signal having a phase difference of 180 degrees different from that of the first frequency signal. Since the supply of the 1-frequency signal, the supply of the second-frequency signal, or the switching of the three modes without these supply is selectively performed, the driving direction component of the elliptic motion can be increased or decreased, or can be driven by the driving force as it is.

[0019]

Embodiments Embodiments will be described in more detail below with reference to the drawings. FIG. 1 is a schematic view showing an embodiment of an ultrasonic actuator according to the present invention. Elastic body 11
Is a base portion 11a and two projecting portions (driving force extracting portion) 1
1b and 11c, and the material thereof is metal such as stainless steel or aluminum alloy, or plastic.

The elastic body 11 has an upper surface (first
Main piezoelectric bodies 12 and 13 are arranged on the right side surface (second surface) and the left side surface (third surface) in the traveling direction (arrow X) of the base portion 11a. Corresponding to 13,
Sub-piezoelectric bodies 12R, 13R and sub-piezoelectric bodies 12L, 13L are provided. In addition, the upper surface (first surface) of the base portion 11a
On the rear side of the traveling direction (arrow X) of the main piezoelectric bodies 12, 13 of
A piezoelectric body 14 for ground is provided, and a piezoelectric body 15 for detection is provided on the front side.

The main piezoelectric bodies 12 and 13 are electromechanical conversion elements for generating a longitudinal vibration L1 mode and a bending vibration B4 mode. A voltage at the A terminal is applied to the main piezoelectric body 12, and a voltage at the B terminal is applied to the main piezoelectric body 13. In this embodiment, the main piezoelectric bodies 12 and 13 are polarized in the thickness direction as shown in FIG. 3A, and the polarization directions are the same. Further, the voltage of the A terminal and the voltage of the B terminal have the same frequency and are out of phase with each other by π / 2. 2
The polarization of the two piezoelectric bodies 12 and 13 may be opposite to each other. Sub-piezoelectric bodies 12R, 13R and sub-piezoelectric bodies 12L, 1
3L is polarized in the thickness direction as shown in FIG. 3B, and the polarization directions of the sub-piezoelectric bodies 12R and 12L are the same as the main piezoelectric body 12 with respect to the bonding surface. The piezoelectric bodies 13R and 13L are in the same direction as the main piezoelectric body 13 with respect to the bonding surface.

The piezoelectric body 14 for grounding is an electrical-electrical conversion element for grounding, and unlike other piezoelectric bodies, it is not polarized and does not have an electromechanical conversion function.
In this piezoelectric body 14, the electrodes on the surface and the elastic body 11 are electrically connected by a conductive paint or the like. The reason why the non-polarized piezoelectric body 14 is arranged here is that the elliptical movements generated on the driving surfaces of the two protrusions 11b and 11c have substantially the same shape in order to balance the weight with the piezoelectric body 15 for detection described later. This is to eliminate the difference between the driving forces when reciprocating.

The piezoelectric body 15 for detection converts the vibration state of the elastic body 11 into an electric signal and transmits it to the P terminal. This electric signal includes two different vibration modes, which are a vibration state of the fourth bending vibration mode and a vibration state of the first longitudinal vibration mode, in a degenerated form. Then, a signal having a magnitude substantially corresponding to the combined vibration amplitude of the elastic body 11 is obtained.

FIG. 2 is a diagram for explaining the operation of the ultrasonic motor according to the present invention. First, the driving operation by the main piezoelectric bodies 12 and 13 will be described, and then the sub piezoelectric bodies 12R and 13R;
The operation of the sub-piezoelectric bodies 12L and 13L will be described together.

FIG. 2 (A) shows the changes over time of the two-phase high-frequency voltages A and B input to the ultrasonic actuator from t1.
It is shown at t9. The horizontal axis of FIG. 2A shows the effective value of the high frequency voltage. FIG. 2B shows how the cross section of the ultrasonic actuator is deformed, and shows the temporal change (t1 to t9) of the bending vibration generated in the ultrasonic actuator. FIG. 2C shows how the cross section of the ultrasonic actuator is deformed, and shows the temporal change (t1 to t9) of the longitudinal vibration generated in the ultrasonic actuator. Figure 2
(D) shows the protrusions 11b and 11 of the ultrasonic actuator.
3 shows temporal changes (t1 to t9) of the elliptic motion generated in c and c.

Next, the operation of the ultrasonic actuator of this embodiment will be described for each time change (t1 to t9).
At time t1, as shown in FIG. 2A, the high frequency voltage A generates a positive voltage, and the high frequency voltage B similarly generates the same positive voltage. As shown in FIG. 2B, the bending motions due to the high frequency voltages A and B cancel each other out, and the masses Y1 and Z1 have zero amplitude. Further, as shown in FIG. 2C, the longitudinal vibrations due to the high frequency voltages A and B are generated in the extending direction. The mass points Y2 and Z2 show the maximum elongation around the node X, as indicated by the arrow. As a result, as shown in FIG. 2D, the above-mentioned both vibrations are combined, and the mass Y
The synthesis of the motion of 1 and Y2 becomes the motion of the mass point Y, and
The movement of the mass points Z1 and Z2 becomes the movement of the mass point Z.

At time t2, as shown in FIG. 2A, the high frequency voltage B becomes zero and the high frequency voltage A generates a positive voltage. As shown in FIG. 2 (B), a bending motion is generated by the high frequency voltage A, the mass point Y1 oscillates in the positive direction, and the mass point Z1 oscillates in the negative direction. Further, as shown in FIG. 2 (C), longitudinal vibration due to the high frequency voltage A occurs, and the mass points Y2 and Z2 contract more than at time t1. As a result, as shown in FIG. 2D, the above-mentioned both vibrations are combined, and the mass Y
And Z move clockwise relative to the time t1.

At time t3, as shown in FIG. 2A, the high frequency voltage A generates a positive voltage and the high frequency voltage B similarly generates the same negative voltage. As shown in FIG. 2 (B), the bending motions due to the high frequency voltages A and B are combined and amplified, and the mass point Y1 is amplified in the positive direction more than at the time t2, showing the maximum positive amplitude value. Mass point Z1 is time t2
It is amplified in the negative direction more than, and shows the maximum negative amplitude value. Further, as shown in FIG. 2C, the longitudinal vibrations due to the high frequency voltages A and B cancel each other out, and the mass points Y2 and Z2
And return to their original positions. As a result, as shown in FIG. 2D, both of the above vibrations are combined, and the mass points Y and Z move clockwise relative to the time t2.

At time t4, as shown in FIG. 2 (A), the high frequency voltage A becomes zero and the high frequency voltage B generates a negative voltage. As shown in FIG. 2 (B), a bending motion is generated by the high frequency voltage B, and the amplitude of the mass point Y1 is lower than that at the time t3, and the amplitude is lower than that at the mass point Z1 time t3. Further, as shown in FIG. 2C, longitudinal vibration due to the high frequency voltage B is generated, and the mass points Y2 and Z2 contract.
As a result, as shown in FIG. 2 (D), both of the above vibrations are combined, and the mass points Y and Z move clockwise relative to the time t3.

At time t5, as shown in FIG. 2 (A), the high frequency voltage A produces a negative voltage, and similarly the high frequency voltage B produces the same negative voltage. As shown in FIG. 2B, the bending motions due to the high frequency voltages A and B cancel each other out, and the masses Y1 and Z1 have zero amplitude. Also, FIG.
As shown in (C), the longitudinal vibration due to the high frequency voltages A and B is generated in the contracting direction. The mass points Y2 and Z2 show the maximum contraction around the node X, as indicated by the arrow. As a result, as shown in FIG. 2 (D), both of the above vibrations are combined, and the mass points Y and Z move clockwise relative to the time t4.

As the time t6 to t9 changes,
Flexural vibrations and longitudinal vibrations are generated in the same manner as the above-described principle, and as a result, as shown in FIG. 2D, the mass points Y and Z move clockwise and make an elliptic motion. Based on the above principle, this ultrasonic actuator is configured to generate elliptic motion at the tips of the protrusions 11a and 11b to generate a driving force. Therefore, when the tips of the protrusions 11 b and 11 c are pressed against the relative motion member 16, the elastic body 11 is self-propelled with respect to the relative motion member 16.

As described above, the main piezoelectric bodies 12, 13 are
Is excited by the driving vibration, and longitudinal vibration and bending vibration are generated in the elastic body 11, which become a motion component in the driving direction and a motion component perpendicular to the driving direction, respectively, and an elliptic motion is generated.
In the ultrasonic actuator of this embodiment, the sub piezoelectric body 12
Since R, 13R, 12L, and 13L are bonded to the surfaces (second surface and third surface) that are substantially parallel to the vibration direction of the bending vibration, they do not generate a motion component perpendicular to the driving direction, Only the motion component of elliptic motion is increased. Main piezoelectric body 12, 1
3 to the vibration component [see FIGS. 2 and 4 (B)].
When R, 13R, 12L, and 13L are added, as shown in FIG. 4 (A) or (C), the elliptical motion expands or contracts in the driving direction, and pressurizes and contacts the protrusions 11b and 11c of the elastic body 11. The driving force of the relative movement member 16 can be increased or decreased.

Next, a method of driving the ultrasonic actuator according to the present invention will be described. 5 and 6 are views showing a drive circuit of the ultrasonic actuator according to the present embodiment, and FIG.
FIG. 6 is a diagram for explaining the operation of the switching means of the ultrasonic actuator according to the present embodiment. The drive signal from the oscillator 20a is input to the phase shifter 20b and divided into signals having a phase difference of (1/4) wavelength, and the signals are respectively amplified by the amplifiers 20cA and 20cA.
Input to cB. The drive signals amplified by the amplifiers 20cA and 20cB are switched by the switching means 22A and 22B, respectively.
Is input to the main piezoelectric body 12,
The output of the switching means 22B is transmitted to the sub-piezoelectric bodies 12R and 12L, and is transmitted to the main piezoelectric body 13 and the sub-piezoelectric bodies 13R and 13L.

Next, the switching means 22A will be described with reference to FIG. The switching means 20B has the same circuit configuration, and thus the description thereof is omitted. The drive signal from the amplifier is branched, and one is directly connected to the main piezoelectric body 12. The other branched one is further branched, one is further divided into two via the switching element Q1, passes through the switching elements Q2 and Q3, and is input to the sub-piezoelectric bodies 12L and 12R. Also, 180 ° phase shifter 2
The drive signal branched to 2-1 is further divided into two via the switching element Q4, and the switching element Q5
It is also input to the sub-piezoelectric elements 13L and 13R through Q6.

The speed command means 21 includes a switching means 22A (2
The drive signal is switched by turning ON / OFF the switching elements Q1 to Q6 of 2B). When the switching elements Q1 to Q6 are turned on / off as shown in FIG. 7, the driving component of the elliptic motion corresponding to the switching elements Q1 to Q6 can be reduced or increased, and the driving speed and driving force can be controlled. .

That is, the switching elements Q1 to Q3 are turned off.
When the FF and the switching elements Q4 to Q6 are turned on, the signal (positive signal) as it is from the oscillator 20 is input to the main piezoelectric bodies 12 and 13, and the sub-piezoelectric bodies 12L and 13L;
2R, 13R, 180 ° phase shifter 22-1,
Since a signal whose phase shift is shifted by 180 ° (an inverted signal) is input, the speed becomes “slow”.

The switching elements Q1 to Q3 and Q6 are turned off.
When F and the switching elements Q4 and Q5 are turned ON, a positive signal is input to the main piezoelectric bodies 12 and 13, and the sub piezoelectric body 12
An inverted signal is input to L and 13L, and the sub-piezoelectric body 12
Since no signal is input to R and 13R, the speed becomes "slightly slow".

The switching elements Q1 to Q6 are all OF
When set to F, a positive signal is input to the main piezoelectric bodies 12 and 13, and no signal is input to the sub-piezoelectric bodies 12L and 13L; 12R and 13R, so the speed is “normal” (in the case of FIG. 2). Same as).

When the switching elements Q1 and Q2 are turned on and the switching elements Q3 to Q6 are turned off, the main piezoelectric body 1
A positive signal is input to 2 and 13, and the sub piezoelectric bodies 12L and 1L
A positive signal is input to 3L, and the sub-piezoelectric bodies 12R, 13R
Since there is no signal input to, the speed is "slightly faster".

When the switching elements Q1 to Q3 are turned on and the switching elements Q4 to Q6 are turned off, the main piezoelectric body 1
2, 13 and sub-piezoelectric bodies 12L, 13L; 12R, 13R
A positive signal is input to each of them, and the speed becomes “fast”.

From the above, the driving speed and driving force can be controlled without changing the frequency and voltage of the driving signal.

The present invention is not limited to the embodiments described above, and various modifications and changes are possible, which are also included in the present invention. For example, as the electromechanical conversion element, the piezoelectric body has been described as an example, but an electrostrictive element may be used. Further, in the embodiment of the present invention, the polarization direction with respect to the joint surface of the main piezoelectric body and the sub-piezoelectric body is the same, but even if the main piezoelectric body and the sub-piezoelectric body have opposite polarization directions, the applied voltage If you adjust the sign of
The same effect occurs. For example, when the polarization directions of the main piezoelectric body and the sub-piezoelectric body are opposite to each other, when the speed is desired to be increased, the applied voltage may be opposite between the main piezoelectric body and the sub-piezoelectric material, and when the speed is desired to be reduced. The applied voltage may be the same for the main piezoelectric body and the sub-piezoelectric body. Further, as the different vibration modes, the vibration of the L1-B4 mode has been described as an example, but L1-B2, L1-B6, L1-B8, L2-B.
Other modes such as 4 may be used. L1
The example of the -B4 mode vibration has been described, but the same can be applied to an annular ultrasonic motor that generates a progressive vibration wave on the surface of an elastic body by an electromechanical conversion element. Although the example of the self-propelled type has been described, the elastic body side may be fixed and a long relative movement member or the like may be moved.

[0043]

As described above in detail, according to the present invention, in addition to the main electromechanical conversion element for causing the elastic body to generate an elliptic motion composed of a driving direction component and a component in the direction perpendicular to the driving direction, the driving is performed. Since the sub-electro-mechanical conversion element for generating the motion of the directional component is provided, the elliptic motion expands or contracts in the driving direction, whereby the driving force can be increased or decreased, and the driving force or the driving speed can be controlled. it can.

By providing the sub-electromechanical conversion element on a surface (second surface or third surface) substantially parallel to the amplitude direction of the bending vibration, the sub-electro-mechanical conversion element is perpendicular to the driving direction of the elliptic motion of the driving force extracting portion. It is possible to increase or decrease only the driving direction component of the elliptic motion without generating the bending motion that causes the direction component, and it is possible to efficiently control the driving force or the driving speed.

Further, the drive signal to the sub electromechanical conversion element is composed of the first frequency signal and the second frequency signal having a phase difference of 180 degrees different from that of the first frequency signal. Since the supply of the 1-frequency signal, the supply of the second-frequency signal, or the switching of the three modes without these supply is selectively performed, it can be driven by the increase or decrease of the driving direction component of the elliptic motion or the driving force as it is, which is fast,
It is possible to perform normal or slow control or drive control such as fast, moderately fast, normal, moderately slow, or slow.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of an ultrasonic actuator according to the present invention.

FIG. 2 is a diagram illustrating a driving operation of the ultrasonic actuator according to the present embodiment.

FIG. 3 is a diagram showing the polarization direction of the electromechanical conversion element of the ultrasonic actuator of the present embodiment.

FIG. 4 is a diagram showing an operation of a sub electromechanical conversion element of the ultrasonic actuator according to the present embodiment.

FIG. 5 is a diagram showing a drive circuit of the ultrasonic actuator according to the present embodiment.

FIG. 6 is a diagram showing a drive circuit (switching means) of the ultrasonic actuator according to the present embodiment.

FIG. 7 is a diagram for explaining the operation of the switching means of the ultrasonic actuator according to the present embodiment.

FIG. 8 is a diagram showing a conventional example of a linear ultrasonic actuator.

FIG. 9 is a schematic view showing an example of a modified degenerate vertical L1-bending B4 mode flat plate motor.

[Explanation of symbols]

 11 Elastic body 12, 13 Main piezoelectric body 12L, 12R, 13L, 13R Sub-piezoelectric body 20 Oscillator 21 Speed command means 21-1 180 degree phase shifter 22 Switching means Q1-Q6 Switching element

Claims (4)

[Claims] 1. A driving force generating means for generating a main drive signal and a sub drive signal, a main electromechanical conversion element excited by the main drive signal, and a sub electromechanical conversion element excited by the sub drive signal. An elastic body having a first surface, a second surface and a driving force extracting portion, wherein the main electromechanical conversion element is bonded to the first surface and the sub electromechanical conversion element is bonded to the second surface. And a drive signal switching unit that selectively supplies the sub drive signal to the sub electromechanical conversion element while supplying the main drive signal to the main electromechanical conversion element, the main electromechanical conversion element Generates an elliptical motion in the driving force extracting portion of the elastic body, the driving force extracting portion having a driving direction component and a component in a direction perpendicular to the driving direction. Generates motion in the driving direction component An ultrasonic actuator characterized by: 2. A driving force generating means for generating a main drive signal and a sub drive signal, a main electromechanical conversion element excited by the main drive signal, and first and second exciters excited by the sub drive signal. A sub electromechanical conversion element, a first surface, a second surface, a third surface, and a driving force extracting portion, wherein the main electromechanical conversion element is joined to the first surface;
And an elastic body in which a second sub electromechanical conversion element is joined to the second surface and the third surface, and supplies the main drive signal to the main electromechanical conversion element and to the sub electromechanical conversion element. Drive signal switching means for selectively supplying the sub drive signal, wherein the main electromechanical conversion element includes a drive direction component in the drive force extraction portion of the elastic body and a component in a direction perpendicular to the drive direction. An ultrasonic actuator, wherein the first and second sub-electromechanical conversion elements generate a motion of a driving direction component in the driving force extracting portion of the elastic body. 3. The ultrasonic actuator according to claim 1 or 2, wherein the second surface and / or the third surface of the elastic body is a surface parallel to a vertical component of the elliptic motion. Characteristic ultrasonic actuator. 4. The ultrasonic actuator according to claim 1, wherein the sub-driving signal has a first frequency signal and a second frequency signal having a phase difference of 180 degrees different from that of the first frequency signal. The drive signal switching means selectively supplies the first frequency signal or the second frequency signal to each of the sub electromechanical conversion elements, or switches between three modes without supply of these. An ultrasonic actuator characterized by performing.