JPH07298651A - Ultrasonic actuator - Google Patents

Abstract

PURPOSE:To enable improvement of driving force and driving efficiency by alternately arranging electric/mechanical conversion elements at the first joining surface and the second joining surface for the driving direction. CONSTITUTION:An elastic material 11 has a base portion 11a and a couple projected areas 11b, 11c and is made of a metal such as stainless steel or plastic material, etc. This elastic material 11 is provided with piezoelectric materials 12-1, 12-4 at the upper surface of the base portion 11a, namely at the first joining surface 11a-1 and also provided with piezoelectric materials 12-2, 12-3 at the lower surface of the base portion 11a, namely at the second joining surface 11a-2 in the internal area than the piezoelectric materials 12-1, 12-4 when viewed from the joining surface and the vertical direction. Moreover, the elastic material 11 is joined at, the center thereof with a ground portion 13 consisting of a conductor and it plays a role of ground by grounding the gound portion 13. Since tars ground portion 13 is arranged at the center of the elastic material 11, it is located at the positon of the node for both longitudinal vibration and flexural vibration to reduce energy loss for each vibration.

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. 7 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. 8 is a schematic view showing a conventional example of a modified degenerate vertical L1-bending B4 mode flat plate motor.
8A is a front view, FIG. 8B is a side view, and FIG. 8C 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 (bending) vibration B4 mode.
The protrusions 1b and 1c of the elastic body 1 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. In the conventional ultrasonic actuator shown in FIG. 8, the protrusions 1b and 1c of the elastic body 1 are
By joining the piezoelectric bodies 2 and 3 to the surface on the side opposite to the center of the elastic body 11 and applying an electric signal to the piezoelectric bodies 2 and 3, longitudinal vibration and bending are caused in the entire elastic body 11. It was causing vibration.

[0008]

In the actuator of FIG. 8 described above, it was necessary to make the elliptic motion larger in order to obtain a large driving force. However, since the elastic body attenuates the vibration inside, the electromechanical conversion element that is the vibration source needs a bonding area of a certain size. That is, in the conventional technique, since the electromechanical conversion element is bonded to only a part of the elastic body, the vibration amplitude of the elastic body cannot be increased, and the driving force and the driving efficiency cannot be improved. There was a problem.

To solve this problem, it is conceivable to join the electromechanical conversion element to the entire elastic body, but this ultrasonic actuator generates longitudinal vibration and bending vibration in the entire elastic body, Since a driving force is generated by superimposing two vibrations, a bending force applied from the electromechanical conversion element and a bending force opposite to each other may be generated in the elastic body, which causes a loss of input energy. ,
The driving force and driving efficiency cannot be improved.

An object of the present invention is to provide an ultrasonic actuator capable of solving the above-mentioned problems and improving performance such as driving force and driving efficiency.

[0011]

In order to solve the above-mentioned problems, a first solution of an ultrasonic actuator according to the present invention is an electromechanical conversion element excited by a drive signal,
The electromechanical transducer has first and second joint surfaces for joining, and when the electromechanical transducer is excited, longitudinal vibration oscillating in the same direction as the driving direction and bending vibration oscillating in the direction perpendicular to the driving direction are generated. Between the elastic body that is generated and generates an elliptic vibration that is a combination of the longitudinal vibration and the bending vibration in the driving force extraction section and is brought into pressure contact with the driving force extraction section of the elastic body, and between the elastic body. In an ultrasonic actuator composed of a relative motion member that performs relative motion, the electromechanical conversion elements are arranged alternately on the first joint surface and the second joint surface with respect to a driving direction. It has a feature.

A second solution is the ultrasonic actuator of the first solution, wherein the electromechanical conversion element is
It is characterized in that the first joint surface and the second joint surface do not overlap each other when viewed in a direction perpendicular to the first joint surface and the second joint surface.

A third solving means is the ultrasonic actuator of the first solving means, wherein the electromechanical conversion element is
It is characterized in that the first joint surface and the second joint surface partially overlap each other when viewed in a direction perpendicular to the surfaces.

A fourth solving means is the ultrasonic actuator of the first solving means, wherein the electromechanical conversion element is
It is characterized in that its center substantially coincides with the position of the antinode of the bending vibration.

A fifth solving means is the ultrasonic actuator of the first solving means, wherein in the ultrasonic actuator according to claim 1, the electromechanical conversion element has a length corresponding to a half wavelength of the bending vibration. It is characterized by being the length of.

[0016]

According to the first solution of the present invention, the electromechanical conversion element includes the first joint surface and the second joint surface in the driving direction.
Since they are alternately arranged on the joint surface, longitudinal vibration and bending vibration can be amplified.

According to the second solution, the electromechanical conversion element does not overlap the first joint surface and the second joint surface when viewed from the direction perpendicular to the first joint surface and the second joint surface. The electromechanical conversion element provided on the surface will not damp the vibration of the electromechanical conversion element provided on the other surface.

According to the third solving means, the electromechanical conversion element is arranged so as to partially overlap the first joint surface and the second joint surface when viewed from a direction perpendicular to the first joint surface and the second joint surface. The joint area of the electromechanical conversion element with respect to the body is increased as a whole within the range where they do not adversely affect each other, and the driving efficiency is improved.

According to the fourth solution, the electromechanical conversion element has its center substantially aligned with the position of the antinode of the bending vibration, so that the set order (for example,
Since the electromechanical conversion element is provided at a position corresponding to the (fourth) bending vibration, ideal bending vibration can be generated.

According to the fifth solving means, since the electromechanical conversion element has a length equal to a half wavelength of the bending vibration, the bending force generated from the electromechanical conversion element is increased. Therefore, it is possible to reduce the loss of vibration energy.

[0021]

【Example】

(First Embodiment) Hereinafter, the embodiments will be described in more detail with reference to the drawings. FIG. 1 is a schematic diagram showing a first embodiment of an ultrasonic actuator according to the present invention.
The elastic body 11 has a base portion 11a and two projecting portions (driving force extracting portions) 11b and 11c, and the material thereof is metal such as stainless steel or aluminum alloy, or plastic.

In this elastic body 11, piezoelectric bodies 12-1 and 12- are provided on the upper surface (first joining surface 11a-1) of the base portion 11a.
4 is provided, and the piezoelectric body 12 is located inside the piezoelectric bodies 12-1 and 12-4 on the lower surface (second bonding surface 11a-2) of the base portion 11a when viewed in a direction perpendicular to the joint surface. -2
12-3 is provided.

A ground portion 13 made of a conductor is joined to the center of the elastic body 11, and the ground portion 13 is grounded to serve as a ground. Since the ground portion 13 is arranged at the center of the elastic body 11, it is at a node position for both longitudinal vibration and bending vibration, and energy loss for each vibration can be reduced. .

FIG. 3 is a diagram showing the relationship between the actuator of the first embodiment and bending vibration. Piezoelectric bodies 12-1 to 12-
4 is the first joint surface 11a-1 of the elastic body 11 so as to match the antinode position of the fourth-order bending vibration generated in the elastic body 11.
And the second joint surface 11a-2 are alternately arranged,
Piezoelectric bodies 11-1 and 11-4 and piezoelectric bodies 11-2 on each surface,
The polarization directions of 11-3 are made to coincide with each other, as shown in FIG.

The center of each of the piezoelectric bodies 12-1 to 12-4 is located at the antinode of bending vibration (shown by a broken line in FIG. 3B). Therefore, bending vibration can be efficiently generated. In addition, the piezoelectric body 12-1
The lengths of # 12 to # 4 are substantially the same as the length of 1/2 wavelength of bending vibration. For this purpose, the piezoelectric body 12
The bending forces generated from -1 to 12-4 do not cancel each other out, and the loss of vibration energy can be reduced.

Further, the piezoelectric bodies 12-1 to 12-4 are arranged so as not to overlap the first bonding surface 11a-1 and the second bonding surface 11a-2 when viewed from the direction perpendicular to the surfaces. Therefore, the piezoelectric body 1 provided on the first bonding surface 11a-1
2-1 and 12-4 and the piezoelectric bodies 12-2 and 12-3 provided on the second joint surface 11a-2 do not mutually attenuate the vibration.

The protrusions 11b and 11c of the elastic body 11 include
The relative movement member 14 is brought into pressure contact with a pressure member (not shown).

The piezoelectric members 12-1 to 12-4 have longitudinal vibration L1.
Mode and a bending vibration B4 mode are electromechanical conversion elements, and the piezoelectric bodies 12-1 and 12-2 include:
The voltage of the A terminal is applied, and the voltage of the B terminal is applied to the piezoelectric bodies 12-3 and 12-4. In this embodiment, the piezoelectric bodies 12-1 to 12-4 are polarized in the thickness direction as shown in FIG. 1B, and the piezoelectric bodies 12-1 and 12-4 and the piezoelectric bodies 12-2 and 12-4. The polarization directions of 12-3 are opposite to each other. The piezoelectric bodies 12-1 and 12-4 and the piezoelectric body 12
The polarizations of −2 and 12-3 may be in the same direction.

The drive signal is divided into two systems, A phase and B phase, and the temporal phase difference is shifted by π / 2. As a result, the elastic body 11 has a longitudinal vibration in the primary mode in which the longitudinal vibration due to the drive signal from the A phase and the longitudinal vibration due to the drive signal from the B phase are combined, and the bending vibration due to the drive signal from the A phase. And a bending vibration of a fourth order, which is a combination of bending vibrations due to the driving signals from the B phase, is generated as a motion component in the driving direction and a motion component perpendicular to the driving direction, and an elliptic motion is generated. Thereby, the elastic body 11
Relative movement member 1 in pressure contact with the protruding portions 11b, 11c of the
4. Relative movement with 4.

FIG. 2 is a diagram for explaining the operation of the ultrasonic motor according to the present invention. FIG. 2A shows time changes of the two-phase high frequency voltages A and B input to the ultrasonic actuator at t1 to t9. The horizontal axis of FIG. 2A shows the effective value of the high frequency voltage. FIG. 2B shows a state of deformation of the cross section of the ultrasonic actuator, and shows a temporal change (t1 to t) of bending vibration generated in the ultrasonic actuator.
9) is shown. 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. FIG. 2D shows the protrusion 11 of the ultrasonic actuator.
b and 11c, the temporal changes of the elliptical motions (t1 to
t9) is shown.

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. 2 (A), 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. 2 (A), 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 produces 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 an 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 movement member 14, the elastic body 11 performs relative movement with respect to the relative movement member 14. In the ultrasonic actuator of the first embodiment, the driving speed and driving force can be controlled by changing the frequency and voltage of the driving signal.

In this embodiment, the piezoelectric bodies 12-1 to 12-4 are used.
Is the first joint surface 11a-1 and the second joint surface 11a- so as to match the antinode position of the bending vibration generated in the elastic body 11.
2 and the piezoelectric elements 12-1 to 12-1 are alternately arranged.
Since the polarization directions of 2-4 are the same,
It is possible to amplify the longitudinal vibration due to the drive signal from the A phase and the longitudinal vibration due to the drive signal from the B phase, and the bending vibration due to the drive signal from the A phase and the bending vibration due to the drive signal from the B phase. Therefore, the vibration amplitude of the longitudinal vibration and bending vibration of the elastic body 11 can be increased. As a result, the elliptic motion generated in the protrusions 11b and 11c can be increased, so that the driving force of the relative motion member 14 brought into pressure contact with the protrusions 11b and 11c can be increased, and the driving efficiency can be increased. Can be improved.

Further, since the length of each of the piezoelectric bodies 12-1 to 12-4 is set to a half wavelength of the bending vibration of the elastic body 11, the first joint surface 11a-1 and the second joint surface 11a-. 2 and the piezoelectric bodies 12-1 and 12-4 and the piezoelectric body 12-
The bending forces respectively generated from Nos. 2 and 12-3 do not cancel each other out, and the loss of vibration energy can be reduced.

In the first embodiment, the piezoelectric bodies 12-1 to 12-1
The length of 12-4 has been described as an example of a length corresponding to a half wavelength of bending vibration of the elastic body 11, but the piezoelectric bodies 12-1 to 12-1.
The length 2-4 may be slightly longer than the half wavelength of the bending vibration of the elastic body 11. In this case, the bending vibration has a small amplitude, but the piezoelectric bodies 12-1 to
The joint area of 12-4 becomes large, and the amplitude of longitudinal vibration becomes large. As a result, the locus of the elliptic motion of the protrusions 11b and 11c becomes horizontally long, and the driving force in the driving direction can be increased. However, if the lengths of the piezoelectric bodies 12-1 to 12-4 are too long, bending vibration is less likely to occur and elliptic movement is less likely to occur, so that the driving force and the driving efficiency are reduced. It is desirable not to make it longer than this.

(Second Embodiment) FIG. 4 is a view showing a second embodiment of the ultrasonic actuator according to the present invention. In addition,
The parts having the same functions as those in the first embodiment are designated by the same reference numerals, and the duplicated description will be omitted. In the ultrasonic actuator of the second embodiment, the elastic body 11 is arranged so that the piezoelectric bodies 11-1 to 11-8 are aligned with the antinode position of the eighth vibration (FIG. 4B) generated in the elastic body 11. First joint surface 11a of
-1 and the second joint surface 11a-2 are alternately arranged. The length of each of the piezoelectric bodies 11-1 to 11-8 is set to be substantially equal to the half-wave length of bending vibration.

In the second embodiment, the elastic body 11 includes
Longitudinal vibration of the primary mode in which longitudinal vibration due to the drive signal from the A phase and longitudinal vibration due to the drive signal from the B phase are combined,
A bending vibration of an 8th mode is generated, which is a combination of bending vibrations due to the driving signal from the A phase and bending vibrations due to the driving signal from the B phase, which are the motion component in the driving direction and the motion perpendicular to the driving direction. It becomes a component and causes elliptical motion.

(Third Embodiment) FIG. 5 is a block diagram showing a third embodiment of the ultrasonic actuator according to the present invention, FIG.
[FIG. 11] is a diagram for explaining the operation of the speed control unit of the ultrasonic actuator according to the third embodiment. The ultrasonic actuator of the third embodiment includes an oscillating unit 20a, a phase shifting unit 20b, amplifying units S and M, a speed control unit 21, a signal switching unit 22 and the like.

The drive signal from the oscillator 20a is supplied to the phase shifter 2
The signal is input to 0b, is divided into two signals having a phase difference of 90 degrees, and is amplified by the amplification unit M and / or the amplification unit S, respectively. The drive signal from the amplifier M is further divided into two, one of which is input to the piezoelectric body A1 (B1) and the other of which is
One is the piezoelectric body A via the switching element Q1 (Q4).
2 (B2) is input. The drive signal from the amplifier S is also
It is further divided into two, one is input to the piezoelectric body A2 (B2), and the other is a 180 ° phase shifter 22-1 (22-
2) and the piezoelectric element A2 (B2) via the switching element Q3 (Q6). The amplification degree of the amplification section is such that the amplification section M> the amplification section S.

The speed control unit 21 turns ON / OFF the switching elements Q1 to Q6 of the switching means 22,
The drive signal is switched. Switching elements Q1 to Q6
When is turned on / off as shown in FIG. 6, the driving component of the elliptic motion corresponding to the turning can be reduced or increased, and the driving speed and driving force can be controlled.

First, the switching elements Q1, Q2, Q
4, Q5 OFF, switching elements Q3, Q6 ON
To At this time, the signal amplified by the amplifier M is input to the piezoelectric body A1. A signal (inverted signal) that is amplified by the amplification unit S and is 180 ° out of phase by the 180 ° phase shifter 22-1 is input to the piezoelectric body A2. The signal amplified by the amplifier M is input to the piezoelectric body B1. A signal (inverted signal) which is amplified by the amplification unit S and whose phase is shifted by 180 ° by the 180 ° phase shifter 22-2 is input to the piezoelectric body B2. That is, since a positive signal is input to the piezoelectric bodies A1 and B1 and an inverted signal is input to the piezoelectric bodies A2 and B2, the speed becomes slow.

Second, the switching elements Q1 to Q6 are all turned off. At this time, the amplifying portion M is attached to the piezoelectric body A1.
The signal amplified by is input. No drive signal is input to the piezoelectric body A2. The signal amplified by the amplifier M is input to the piezoelectric body B1. No drive signal is input to the piezoelectric body B2. That is, the piezoelectric bodies A1 and B
Since no positive signal is input to 1 and no signal is input to the piezoelectric bodies A2 and B2, the speed becomes normal (same as the conventional one).

Third, switching elements Q1, Q3, Q
4, Q6 OFF, switching elements Q2, Q5 ON
To At this time, the signal amplified by the amplifier M is input to the piezoelectric body A1. The drive signal amplified by the amplifier S is input to the piezoelectric body A2. Piezoelectric body B
The signal amplified by the amplification unit M is input to 1. The drive signal amplified by the amplifier S is input to the piezoelectric body B2. That is, since the positive signals are input to the piezoelectric bodies A1 and B1 and the positive signals that have been slightly amplified by the amplification unit S are input to the piezoelectric bodies A2 and B2, the speed is slightly increased.

Fourth, switching elements Q2, Q3, Q
5, Q6 OFF, switching elements Q1, Q4 ON
To At this time, the signal amplified by the amplifier M is input to the piezoelectric body A1. The drive signal amplified by the amplifier M is input to the piezoelectric body A2. Piezoelectric body B
The signal amplified by the amplification unit M is input to 1. The drive signal amplified by the amplifier M is input to the piezoelectric body B2. That is, since the positive signals are input to the piezoelectric bodies A1 and B1 and the positive signals greatly amplified by the amplifying section M are input to the piezoelectric bodies A2 and B2, the speed is increased.

According to the third embodiment, the driving speed and the driving force can be controlled even with the frequency fixed to the highest driving efficiency.

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, as the different vibration modes, the vibrations in the L1-B4 and L1-B8 modes have been described as an example, but L1-B2, L1-B6, L2-
Other modes such as B4 may be used. 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.

[0051]

As described above in detail, according to the first aspect, the electromechanical conversion elements are alternately arranged on the first joint surface and the second joint surface with respect to the driving direction. Vibration and bending vibration can be amplified.

According to claim 2, the electromechanical conversion element comprises:
Since the first joining surface and the second joining surface do not overlap each other when viewed from the direction perpendicular to the first joining surface and the second joining surface, the electromechanical conversion element provided on one surface is provided on the other surface. It does not damp the vibration of the element.

According to claim 3, the electromechanical conversion element comprises:
Since the first joining surface and the second joining surface partially overlap each other when viewed in the direction perpendicular to the surfaces, the joining area of the electromechanical conversion element with respect to the elastic body increases as a whole as long as they do not adversely affect each other. The driving efficiency is improved.

According to claim 4, the electromechanical conversion element comprises:
Since the center of the electromechanical conversion element is set to be substantially coincident with the position of the antinode of the bending vibration, the electromechanical conversion element is provided at a position corresponding to the bending vibration of the set order (for example, fourth order). Bending vibration can be generated.

According to claim 5, the electromechanical conversion element comprises:
Since the length of the bending vibration is half the wavelength of the bending vibration, the bending forces generated from the electromechanical conversion elements do not cancel each other out, and it is possible to reduce the loss of vibration energy. Has the effect of.

[Brief description of drawings]

FIG. 1 is a schematic view showing a first 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 first embodiment.

FIG. 3 is a diagram showing the relationship between the ultrasonic actuator of the first embodiment and bending vibration.

FIG. 4 is a diagram showing a relationship between an ultrasonic actuator of the second embodiment and bending vibration.

FIG. 5 is a block diagram showing a third embodiment of the ultrasonic actuator according to the present invention.

FIG. 6 is a diagram for explaining the operation of the speed control unit of the ultrasonic actuator according to the third embodiment.

FIG. 7 is a diagram showing a conventional example of a linear ultrasonic actuator.

FIG. 8 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 12-1, 12-2, 12-3, 12-4 Piezoelectric body 13 Ground part 14 Relative motion member A1, A2, B1, B2 Piezoelectric body 20a Oscillator 20b Phase shifting part S, M Amplifying part 21 Speed control Part 21-1, 21-2 180 degree phase shifter 22 switching part Q1-Q6 switching element

Claims (5)

[Claims] 1. An electromechanical conversion element excited by a drive signal; first and second parts for joining the electromechanical conversion element
Excitation of the electromechanical conversion element having a joint surface generates longitudinal vibration that oscillates in the same direction as the driving direction and bending vibration that oscillates in the direction perpendicular to the driving direction, and the longitudinal vibration and the bending vibration are combined. An elastic body that generates the generated elliptical vibration in the driving force extraction portion; and a relative motion member that makes pressure contact with the driving force extraction portion of the elastic body and performs relative movement with the elastic body. In the ultrasonic actuator, the electromechanical conversion elements are alternately arranged on the first joint surface and the second joint surface with respect to a driving direction. 2. The ultrasonic actuator according to claim 1, wherein the electromechanical conversion element does not overlap the first bonding surface and the second bonding surface when viewed from a direction perpendicular to the surfaces. And ultrasonic actuator. 3. The ultrasonic actuator according to claim 1, wherein the electromechanical conversion element partially overlaps the first joint surface and the second joint surface when viewed from a direction perpendicular to the first joint surface and the second joint surface. And ultrasonic actuator. 4. The ultrasonic actuator according to claim 1, wherein a center of the electromechanical conversion element substantially coincides with a position of an antinode of the bending vibration. 5. The ultrasonic actuator according to claim 1, wherein the electromechanical conversion element has a length corresponding to a half wavelength of the bending vibration.