JPH08331874A - Ultrasonic actuator - Google Patents

Abstract

PURPOSE: To provide an ultrasonic actuator which can be moved one- dimensionally or two-dimensionally in a plane and is easy to incorporate in a cylindrical part. CONSTITUTION: An ultrasonic actuator 10 has an annular elastic element 11 and piezoelectric devices 12 and 13 which are bonded to the plane of the annular elastic element 11 at positions facing each other. If driving signals are inputted to the piezoelectric devices 12 and 13, the elastic element 11 is excited and the non-axis-symmetry vibration and the bending vibration are generated and the elastic element 11 is made to run automatically in ±x directions by its contraction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic actuator, and more particularly to an ultrasonic actuator utilizing degeneracy of non-axisymmetric vibration and bending vibration.

[0002]

2. Description of the Related Art Conventionally, an ultrasonic actuator of this type generates a progressive vibration wave in an annular elastic body by the excitation of an electro-mechanical energy conversion element, and a relative pressure contact with the elastic body is made. The moving element (rotor), which is a moving member, is driven.

On the other hand, a linear type ultrasonic actuator has a vibrating electro-mechanical energy conversion element arranged at one end of a rod-shaped elastic body and a vibration absorbing member for absorbing reflection of traveling waves at the other end. The electro-mechanical energy conversion element is arranged to generate a traveling wave from one of the elastic bodies to the other, and the moving body that is in pressure contact with the elastic body is driven.

[0004]

The former ultrasonic actuator is incorporated in a lens barrel of a camera, for example, and is used for driving an AF lens by rotating a moving body.

On the other hand, there has been proposed an anti-shake apparatus which corrects image shake by moving a part of the photographing optical system in a plane substantially orthogonal to the optical axis. However, the former actuator cannot be applied because the driving directions are different. On the other hand, the latter actuator is difficult to be incorporated in a cylindrical lens barrel, and there is a problem that the device becomes large in size in order to drive in the two directions of the X direction and the Y direction in a plane perpendicular to the optical axis. .

Further, when the conventional electromagnetic motor characterized by high speed and low torque is used, a gear train is usually required to secure the output torque, and the object to be driven is bidirectional in a plane. In order to move the driven object in each direction, two independent electromagnetic motors and gear trains are required. As a result, the size of the device is increased and the weight is increased, and there is a problem in that responsiveness is reduced and noise is generated due to backlash and the like inevitably present in the gear train.

An object of the present invention is to provide an ultrasonic actuator which can be moved one-dimensionally or two-dimensionally in a plane and can be easily incorporated in a cylindrical portion such as a lens barrel. .

[0008]

In order to solve the above-mentioned problems, an ultrasonic actuator according to a first aspect of the present invention is configured such that an elastic body made of an annular elastic material and a flat surface of the elastic body are joined to each other at opposing positions. And at least a pair of electro-mechanical energy conversion elements that are excited by a drive signal to generate non-axisymmetric vibration and bending vibration in the elastic body, and generate an elliptical motion in a predetermined portion of the elastic body due to degeneration thereof. And a relative movement member that makes pressure contact with the elastic body.

An ultrasonic actuator according to a second aspect is the ultrasonic actuator according to the first aspect, wherein the elastic body has a resonance frequency substantially equal to that of the non-axisymmetric vibration and the bending vibration. The feature is that the ratio of the diameter, the inner diameter, and the plate thickness is adjusted.

An ultrasonic actuator according to a third aspect is the ultrasonic actuator according to the second aspect, wherein the outer diameter is 40.
It is characterized in that the plate thickness is 1.5 mm or more and 50 mm or less, the plate thickness is 1.5 mm or more and 2.0 mm or less, and the ratio of the inner diameter to the outer diameter is 0.4 or more and 0.6 or less.

An ultrasonic actuator according to a fourth aspect is the ultrasonic actuator according to any one of the first to third aspects, characterized in that a driving force extracting member is provided at the predetermined portion of the elastic body.

An ultrasonic actuator according to a fifth aspect is the ultrasonic actuator according to the fourth aspect, characterized in that the contact portion of the driving force extracting member with the relative motion member is a curved body.

An ultrasonic actuator according to a sixth aspect is the ultrasonic actuator according to the fourth or fifth aspect, wherein the driving force extracting member is joined to the surface of the electro-mechanical energy conversion element via an insulating member. It is characterized by

An ultrasonic actuator according to claim 7 is the ultrasonic actuator according to any one of claims 1 to 6, wherein the non-axisymmetric vibration generated in the elastic body has a first-order peripheral order and a first-order mode. It is characterized by a number of non-axisymmetric vibration modes.

An ultrasonic actuator according to an eighth aspect is the ultrasonic actuator according to the seventh aspect, wherein the bending vibration generated in the elastic body is a first-order bending vibration mode.

An ultrasonic actuator according to a ninth aspect is the ultrasonic actuator according to any one of the first to eighth aspects, wherein the electro-mechanical energy conversion element is the first element.
Two sets of one direction and two directions are provided on one side or both sides of the elastic body.

[0017]

According to the ultrasonic actuator of the first aspect, the annular elastic body and the elastic body are joined to opposite positions on the plane of the elastic body, and are excited by the drive signal to cause non-axisymmetric vibration and bending vibration in the elastic body. And at least a pair of electro-mechanical energy conversion elements that generate an elliptical motion in a predetermined portion of the elastic body due to degeneration thereof, and a relative motion member that makes pressure contact with the elastic body. A motion and a flexural vibration are generated, and due to the degeneration thereof, an elliptical motion is generated in a predetermined portion of the elastic body and the elastic body moves in the surface direction.

According to the ultrasonic actuator of claim 2 or 3, in the ultrasonic actuator according to claim 1, the elastic body is such that the resonance frequencies of the non-axisymmetric vibration and the bending vibration are substantially the same. Moreover, since the ratios of the outer diameter, the inner diameter, and the plate thickness are adjusted, a stable elliptical motion is generated in a predetermined portion of the elastic body, and the elastic body moves in the surface direction.

According to the ultrasonic actuator of claim 4, in the ultrasonic actuator according to any one of claims 1 to 3, since the driving force extracting member is provided at the predetermined portion of the elastic body, the ultrasonic actuator is generated in the elastic body. The driving force can be reliably and efficiently taken out and moved in the plane direction.

According to the ultrasonic actuator of the fifth aspect, in the ultrasonic actuator of the fourth aspect, since the contact portion of the driving force extracting member with the relative motion member is a curved body, does it contribute to the traveling force? Alternatively, the sliding resistance that hinders the progress is reduced as much as possible, and the sheet moves in the surface direction.

According to the ultrasonic actuator of claim 6, in the ultrasonic actuator of claim 4 or 5, the driving force extracting member is joined to the surface of the electro-mechanical energy conversion element via an insulating member. Because
Even when the driving force extracting member has conductivity, it moves in the plane direction without short circuit.

According to the ultrasonic actuator of claim 7, in the ultrasonic actuator according to any one of claims 1 to 6, the non-axisymmetric vibration generated in the elastic body has a first-order peripheral order. Since the vibration mode is a non-axisymmetric vibration mode having the first-order mode number, the driving force is reliably ensured and the surface moves in the plane direction.

According to the ultrasonic actuator of claim 8, in the ultrasonic actuator of claim 7, since the bending vibration generated in the elastic body is a first-order bending vibration mode, the driving force is appropriately interrupted. Then, it comes to move in the plane direction.

According to the ultrasonic actuator of claim 9, in the ultrasonic actuator of any one of claims 1 to 8, the electro-mechanical energy conversion element is for the first direction and for the second direction. Since two sets of and are provided on one side or both sides of the elastic body, they move in two directions within the plane.

As described above, according to the ultrasonic actuator of the present invention, when the electro-mechanical energy conversion element is excited, the elastic body of the annular shape undergoes expansion and contraction motion and bending vibration. An elliptic motion is generated in a predetermined part of the and the surface moves in the plane direction.

[0026]

【Example】

(First Embodiment) Hereinafter, the embodiments will be described in more detail with reference to the drawings.

1 to 4 are views showing a first embodiment of an ultrasonic actuator according to the present invention, and FIG. 1 (A) is a plan view showing the entire structure, and FIG.
3B is a side view showing the entire structure, FIG. 2 is a perspective view showing an elastic body and a piezoelectric element, FIG. 3A is an explanatory view showing flexural vibrations occurring in the elastic body, FIG. 3B and FIG. 3 (C) is a side view showing flexural vibration occurring in the elastic body, and FIG. 4 (A) to FIG.
(D) is a diagram for explaining the operation. Note that FIG. 3 (A)
Then, for convenience of explanation, only the left half of the elastic body is shown and the right half is omitted.

Ultrasonic actuator 10 of the first embodiment
Is formed on the lower surface of the elastic body 11 and the piezoelectric elements 12 and 13 which are, for example, two electro-mechanical energy conversion elements that are adhered and joined to the upper surface of the elastic body 11, and are formed on the lower surface of the elastic body 11. It is composed of four driving force extracting members 14 to 17 and the like.

As shown in FIG. 2, the elastic body 11 is an annular elastic member and is made of an elastic material such as metal or plastic.

The elastic body 11 is shown in FIGS. 1 (A) and 1 (B).
Dimensions of ring shown in (outer diameter: 2a, inner diameter: 2b, plate thickness:
By setting t) in a range as described later, for example, non-axisymmetric vibration [((1,1))-((1,1)) ^'
Mode: in-plane vibration] and secondary bending vibration (B ₁₂ mode)
Can be matched with.

That is, according to the confirmation results of the present inventors, for example, when the driving frequency f = 40 to 60 kHz, the outer diameter 2a = 40 to 50 mm and the plate thickness t = 1.5 to 2.
Non-axisymmetric vibration [((1,1))-((1,1)) ^'in the range of 0 mm, inner diameter 2b / outer diameter 2a = 0.4 to 0.6
Mode: in-plane vibration] and secondary bending vibration (B ₁₂ mode)
By matching and, degeneracy becomes possible.

In this embodiment, ((1,1))-((1,
1)) ^'The mode and the B ₁₂ mode are degenerated as an example, and the bending vibration node 11a of the B ₁₂ mode at this time is shown in FIG.
It is indicated by a broken line in (A) or FIG.

As shown in FIG. 2, the piezoelectric elements 12 and 13 have a quadrant shape in this embodiment, and are made of PZT or the like. The piezoelectric elements 12 and 13 are polarized as shown in FIG. 1A, and two-phase input voltages A and B are applied to them.

The driving force take-off members 14 to 17 take out an elliptical motion generated by the combined vibration of the non-axisymmetric vibration and the bending vibration of the elastic body 11 and make a relative motion while being in contact with the fixed member 18 (relative motion member). To do. Driving force extracting member 14
1 to 17, the lower surface of the elastic body 11 is provided at four locations near the outer edge of the elastic body 11 at regular intervals of 90 °, as shown in FIG. The driving force extracting members 14 to 17 have a spherical body made of silicon nitride or the like attached to the tip end thereof in order to improve wear resistance.

The piezoelectric elements 12 and 13 may be provided on the same plane side as the driving force extracting members 14 to 17, but in this case, even when the driving force extracting members 14 to 17 have conductivity. In order to prevent a short circuit, it is desirable to bond the surfaces of the piezoelectric elements 12 and 13 via an insulating member.

In order to efficiently take out the driving force, it is preferable to provide these driving force taking-out members 14 to 17 so as to avoid the position which becomes the node of the bending vibration, as shown in FIG. 3 (B) or FIG.
Like the driving force output members 14 and 15 shown in (C), it is preferable to set the antinode of vertical vibration in a direction substantially perpendicular to the moving plane, which is generated by the bending vibration mode.

This ultrasonic actuator 10 is shown in FIG.
As shown in (B), by applying the high-frequency voltages A and B to the two piezoelectric elements 12 and 13, a composite vibration of non-axisymmetric vibration and bending vibration is generated, whereby the driving force extracting members 14 and 15 are generated. An elliptical motion is generated at the tip of the and the driving force is generated. Here, G is the ground. The two piezoelectric elements 12 and 13 are polarized so that their polarities are in the same direction, and the high frequency voltages A and B have a time phase difference of π / 2. The polarizations of the two piezoelectric elements 12 and 13 may be opposite to each other.

In FIG. 1B, an oscillator 21 is for oscillating a high frequency signal, and its output is branched, and one of them is a signal having a phase difference of π / 2 by a phase shifter 22. Is connected to the amplifier 23, and the other is directly connected to the amplifier 24. Amplifier 23, 24
The output of is connected to the piezoelectric elements 12 and 13 as high frequency voltages A and B, respectively.

FIG. 4A shows a temporal change of the two-phase high frequency voltages A and B input to the ultrasonic actuator 10 with respect to time t _{1 to} time t ₉ . The horizontal axis of FIG. 4A indicates the effective value of the high frequency voltage. FIG. 4B shows the state of deformation of the side surface of the ultrasonic actuator, and shows the time change of the bending vibration generated in the ultrasonic actuator with respect to time t _{1 to} time t ₉ . FIG. 4C shows the state of deformation of the side surface of the ultrasonic actuator, and shows the time change of the non-axisymmetric vibration generated in the ultrasonic actuator with respect to time t _{1 to} time t ₉ . Furthermore, FIG.
(D) shows the time change of the elliptic motion at the mass points X, Y, and Z of the ultrasonic actuator from time t _{1 to} time t _9.
About.

Next, the ultrasonic actuator 1 according to the present embodiment.
The operation of 0, temporal change with reference to FIG. 4 (t ₁ ~t
₉ ) Explain each item.

At time t ₁ , 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. 4 (A). As shown in FIG. 4B, the bending vibrations due to the high frequency voltages A and B are mutually amplified, and the mass points X1 and Z1 show the maximum negative amplitude,
The mass point Y1 shows the maximum positive amplitude. As shown in FIG. 4C, the amplitude of the non-axisymmetric vibration due to the high frequency voltages A and B is an example, and the amplitudes of the mass points X2, Y2 and Z2 are zero. As a result, as shown in FIG. 4 (D), the above two amplitudes are combined, the synthesis of the movements of the mass points X1 and X2 becomes the movement of the mass point X, and the synthesis of the movements of the mass points Y1 and Y2 is the movement of the mass point Y. Further, the motion of the mass Z1 and the mass Z2 are combined into the motion of the mass Z.

At time t ₂ , the high frequency voltage B becomes zero and the high frequency voltage A generates a maximum positive voltage, as shown in FIG. 4 (A). As shown in FIG. 4 (B), the amplitude of the flexural vibration due to the high frequency voltage A decreases, and the amplitude of the flexural vibration due to the high frequency voltage B becomes zero.
The displacement of each of 1 and the mass point Z1 decreases. Figure 4 (C)
As shown in, the amplitude of the non-axisymmetric motion due to the high frequency voltage A is generated, and the mass point X2 and the mass point Z2 are displaced rightward in the drawing and the mass point Y2 is displaced leftward in the drawing. As a result, as shown in FIG. 4 (D), both of the above vibrations are combined,
The mass points X, Y and Z all make an elliptic motion counterclockwise from the time t ₁ .

At time t ₃ , the high frequency voltage A produces a positive voltage, and the high frequency voltage B produces the same negative voltage, as shown in FIG. 4 (A). As shown in FIG. 4 (B), the bending movements due to the high-frequency voltages A and B cancel each other out and the amplitude becomes zero, and the displacements of the mass points X1, Y1 and Z1 become zero. As shown in FIG. 4 (C), due to the non-axisymmetric motion due to the high-frequency voltages A and B, the mass points X2 and Z2 are displaced further to the right in the drawing and the mass Y2 is further displaced to the left in the drawing. Displace. As a result, as shown in FIG. 4 (D), both of the above vibrations are combined, and the mass points X, Y, and Z are all at time t _2.
Move further counterclockwise than.

At time t ₄ , the high frequency voltage A becomes zero and the high frequency voltage B becomes the maximum negative value, as shown in FIG. 4 (A). As shown in FIG. 4 (B), the amplitude of the bending vibration due to the high frequency voltage B increases, and the mass point X1 and the mass point Y1
And the displacement of each of the mass points Z1 increases. As shown in FIG. 4C, the amount of displacement of the mass points X2 and Z2 to the right in the drawing decreases and the amount of displacement of the mass point Y2 to the left in the drawing is reduced by the non-axisymmetric motion due to the high frequency voltages A and B. Also decreases. As a result, as shown in FIG. 4 (D), both vibrations are combined, and the mass points X, Y and Z are all time t.
Move more counterclockwise than ₃ .

At time t ₅ , as shown in FIG. 4 (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. 5B, the bending motions due to the high frequency voltages A and B are mutually amplified, and the masses X1, Y1 and Z1 respectively have the maximum amplitude. As shown in FIG. 4C, the amplitude of the non-axisymmetric motion due to the high frequency voltages A and B is further reduced, and the mass point X
1, the displacement amounts of the mass point X2 and the mass point Z2 are zero. As a result, as shown in FIG. 4D, both vibrations are combined, and the mass points X, Y and Z move counterclockwise as compared with the time t ₄ .

Thereafter, as the time t ₆ to the time t ₉ changes, bending vibration and non-axisymmetric vibration are generated in the same manner as the above-mentioned principle. As a result, as shown in FIG. , The mass point Y and the mass point Z move counterclockwise to make an elliptic motion.

Based on the above principle, this ultrasonic actuator generates an elliptic motion as shown in FIG. 4D at the tip of each of the driving force extracting members 14 to 17 to generate a driving force. Therefore, the tip ends of the driving force output members 14 to 17 are fixed members 18 which are relative movement members.
When pressure is applied to the elastic body 11, the elastic body 11 is self-propelled with respect to the fixing member 18.

That is, as shown in FIG. 4D, the mass point 15 and the mass point 17 are from time t _{1 to} time t ₃ .
Contact each other while causing an elliptical motion in the counterclockwise direction, so that the elastic body 11 moves leftward in the drawing.

From time t _{3 to} time t ₇ , the mass point 15 and the mass point 17 come into contact with each other while causing an elliptical motion in the counterclockwise direction, so that the elastic body 11 moves leftward in the drawing.

Further, during the time t _{7 to the} time t ₉ , the mass point 15 and the mass point 17 come into contact with each other while making an elliptical motion counterclockwise, so that the elastic body 11 moves leftward in the drawing.

Thereafter, the above-mentioned operation is repeated, and the elastic body 11 moves leftward in the drawing. In this way, it is possible to provide the ultrasonic actuator 10 that can be moved one-dimensionally in a plane and can be easily incorporated in a cylindrical portion such as a lens barrel.

In particular, since the elastic body 11 used in the ultrasonic actuator 10 according to the present invention has an annular shape, it can be applied to, for example, a lens barrel of a camera and used as a drive source for a shake prevention device. is there.

(Second Embodiment) FIGS. 5 to 8 are views showing a second embodiment of the ultrasonic actuator according to the present invention, and FIG. 5 (A) is a front view showing the entire structure, Figure 5
5B and FIG. 5C are both side views showing the overall configuration, FIG. 6 is a perspective view showing an elastic body and a piezoelectric element, and FIG. 7 is an overall view showing a control circuit together. .

In the description of this embodiment, the same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. The first embodiment has a structure that can be moved only in one dimension (± x direction), but this embodiment allows independent movement in two dimensions (± x direction and ± y direction).

Ultrasonic actuator 10-1 of this embodiment
Is a ring-shaped elastic body 11-1 and four quarter-circular ring-shaped piezoelectric elements 12 arranged on the upper surface of the elastic body 11-1 at equal intervals.
a, 13a, 12b and 13b, and four driving force extracting portions 14 to 17 arranged on the upper surface of the elastic body 11-1 at equal intervals.

In this embodiment, the piezoelectric elements 12a and 13a
Although a, 12b, and 13b are all attached to the same surface, the piezoelectric elements 12a and 13a and the piezoelectric elements 12b and 13b may be attached to both surfaces of the elastic body.

In the drive circuit, as shown in FIG. 7, the high frequency signal from the oscillator 21 is branched, and on the other hand, the X direction phase shifter 22X and the Y direction phase shifter 22Y temporally pi. After being phase-shifted by / 2, the X-direction amplifier 23X,
It is connected to the Y-direction amplifier 23Y, and the other is directly connected to the X-direction amplifier 24X and the Y-direction amplifier 24Y.

Each amplifier 23X, 23Y, 24X, 24Y
Through the changeover switch 25, the piezoelectric element 12
a, 12b, 13a and 13b.

When all the contacts of the changeover switch 25 are switched to the X side, the output of the amplifier 23X is connected to the piezoelectric element 12a and the output of the amplifier 24X is connected to the piezoelectric element 13a. Therefore, since the piezoelectric elements 12a and 13a facing each other in the X direction are grouped, it becomes the same as in the case of FIG. 1, and the ultrasonic actuator 10-1 can move in the ± X directions.

Similarly, in the changeover switch 25, when all the contacts are switched to the Y side, the output of the amplifier 23Y is connected to the piezoelectric element 12b and the amplifier 24Y.
The output of is connected to the piezoelectric element 13b. Therefore, Y
Since the piezoelectric elements 12b and 13b facing each other in the direction are grouped, the state shown in FIG.
It is possible to move in the Y direction.

In particular, in this embodiment, the driving force extracting members 14 to 17 have a spherical shape, an ellipsoidal shape or the like so that a uniform driving force can be obtained in the two directions of the X direction and the Y direction. It is desirable that it is a part of the curved body.

(Third Embodiment) This embodiment is different from the second embodiment in that four quasi-circular annular piezoelectric elements 12a, 13a, 12b and 13b are not attached to the elastic body 11-1 but an elastic body is used. An annular piezoelectric element is attached to the piezoelectric element, and four electrodes are attached to the piezoelectric element at equal intervals.

FIG. 8 is an exploded perspective view showing the elastic body and the piezoelectric element in this embodiment. As shown in FIG. 8, an annular piezoelectric element 19 is attached to the upper surface of the annular elastic body 11-2, and a silver electrode is baked on almost the entire upper surface of the piezoelectric element 19. A part of the silver electrode is cut off to form four semicircular electrodes 12c, 13c, 12d, 13d. Instead of removing unnecessary parts after baking the silver electrodes, the unnecessary parts are masked in advance, and four electrodes are provided by forming the silver electrodes by using a thin film forming technique such as vapor deposition. Good.

In this embodiment, since the piezoelectric element 19 can be easily bonded and positioned to the elastic body 11-2, excitation unevenness can be reduced, and the left-right difference (+ x,-) due to the difference in the moving direction can be reduced.
The difference between the moving speeds in the x direction, + y, and -y directions) is also reduced.

(Other Embodiments) The present invention is not limited to the embodiments described above, and various modifications and changes can be made and these are also within the scope of the present invention.

For example, the electric-mechanical energy conversion element has been described with the example of the piezoelectric element, but it may be an electrostrictive element, a magnetostrictive element or the like.

In addition to driving the shake correction lens in two directions, each of the above-described embodiments can be suitably used for an XY stage for microscopes, a feeder for plotter paper, and the like.

[0068]

As described in detail above, the ultrasonic actuator of claim 1 is joined to an annular elastic body at a position opposite to the plane of the elastic body, and is excited by a drive signal to produce the elastic body. Generates non-axisymmetric vibration and bending vibration,
Since at least a pair of electro-mechanical energy conversion elements that generate an elliptic motion in a predetermined portion of the elastic body due to the degeneracy and a relative motion member that makes pressure contact with the elastic body,
It is possible to generate an elliptical motion in a predetermined portion of the elastic body and move it in the plane direction.

The ultrasonic actuator according to claim 2 or 3 is the ultrasonic actuator according to claim 1, wherein the elastic body has an outer surface so that the resonance frequencies of the non-axisymmetric vibration and the bending vibration are substantially the same. Since the ratios of the diameter, the inner diameter, and the plate thickness are adjusted, a stable elliptical motion is generated in a predetermined portion of the elastic body, and the elastic body can move in the surface direction.

An ultrasonic actuator according to a fourth aspect of the present invention is the ultrasonic actuator according to any one of the first to third aspects, in which a driving force extracting member is provided at the predetermined portion of the elastic body. Can be taken out reliably and efficiently and moved in the plane direction.

According to the ultrasonic actuator of the fifth aspect, in the ultrasonic actuator of the fourth aspect, since the contact portion of the driving force extracting member with the relative motion member is a curved body, does it contribute to the traveling force? Alternatively, it is possible to reduce the sliding resistance that hinders the progress as much as possible and move in the surface direction.

An ultrasonic actuator according to a sixth aspect is the ultrasonic actuator according to the fourth or fifth aspect, wherein the driving force extracting member is joined to the surface of the electro-mechanical energy conversion element via an insulating member. Therefore, even when the driving force extracting member has conductivity, the driving force extracting member can move in the surface direction without causing a short circuit.

An ultrasonic actuator according to a seventh aspect is the ultrasonic actuator according to any one of the first to sixth aspects, wherein the non-axisymmetric vibration generated in the elastic body has a first-order peripheral order and a first-order order. Since the mode is a non-axisymmetric vibration mode, the driving force can be reliably ensured and the surface can move in the plane direction.

An ultrasonic actuator according to claim 8 is the ultrasonic actuator according to claim 7, wherein the bending vibration generated in the elastic body is a first-order bending vibration mode.
It is possible to move in the direction of the surface by appropriately interrupting the driving force.

An ultrasonic actuator according to a ninth aspect is the ultrasonic actuator according to any one of the first to eighth aspects, wherein the electro-mechanical energy conversion element is the first.
Since two sets of one direction and two directions are provided on one side or both sides of the elastic body, the elastic body can be moved in two directions within the plane.

As described above, according to the present invention, when the electro-mechanical energy conversion element is excited, expansion and contraction motions and flexural vibrations are generated in the elastic body, and the contraction thereof causes an elliptical motion in a predetermined portion of the elastic body. And can move in the plane direction. In particular,
Since the elastic body has an annular shape, it is suitable for use as a drive source for a shake prevention device by incorporating it into a lens barrel of a camera, for example.

[Brief description of drawings]

FIG. 1A is a plan view showing the overall configuration of the first embodiment, and FIG. 1B is a side view showing the overall configuration of the first embodiment.

FIG. 2 is a perspective view showing an elastic body and a piezoelectric element of the first embodiment.

FIG. 3 is a diagram illustrating an elastic body according to the first embodiment.

FIG. 4 (A) to FIG. 4 (D) of the first embodiment are diagrams for explaining the operation.

FIG. 5 (A) is a front view showing the overall configuration of the second embodiment, and FIGS. 5 (B) and 5 (C) are side views showing the overall configuration of the second embodiment. .

FIG. 6 is a perspective view showing an elastic body and a piezoelectric element according to a second embodiment.

FIG. 7 is an overall view showing a control circuit of a second embodiment together.

FIG. 8 is a perspective view showing an elastic body and a piezoelectric element according to a third embodiment.

[Explanation of symbols]

10, 10-1 Ultrasonic actuator 11, 11-1, 11-2 Elastic body 11a Section 12, 13, 12a, 13a, 12b, 13b Piezoelectric element (electro-mechanical energy conversion element) with silver electrode processed on the surface 12c, 13c, 12d, 13d Electrode plate 14-17 Driving force extraction part 18 Fixed member (relative movement member) 19 PZT 21 Oscillator 22, 22X, 22Y Phase shifter 23, 24, 23X, 24X, 23Y, 24Y Amplifier

Claims (9)

[Claims] 1. An elastic body made of a ring-shaped elastic material is joined to opposing positions on a plane of the elastic body, and is excited by a drive signal to generate non-axisymmetric vibration and bending vibration in the elastic body. An ultrasonic wave comprising: at least a pair of electro-mechanical energy conversion elements that generate an elliptical motion in a predetermined portion of the elastic body by degeneration thereof, and a relative motion member that makes pressure contact with the elastic body. Actuator. 2. The ultrasonic actuator according to claim 1, wherein the elastic body has an outer diameter, an inner diameter, and a plate thickness such that resonance frequencies of the non-axisymmetric vibration and the bending vibration are substantially equal to each other. An ultrasonic actuator, wherein each ratio is adjusted. 3. The ultrasonic actuator according to claim 2, wherein the outer diameter is 40 mm or more and 50 mm or less, the plate thickness is 1.5 mm or more and 2.0 mm or less, and An ultrasonic actuator characterized in that a ratio of inner diameters is 0.4 or more and 0.6 or less. 4. The ultrasonic actuator according to claim 1, wherein a driving force extracting member is provided at the predetermined portion of the elastic body. 5. The ultrasonic actuator according to claim 4, wherein the driving force extracting member has a curved surface at a contact portion with the relative motion member. 6. The ultrasonic actuator according to claim 4 or 5, wherein the driving force extracting member is joined to a surface of the electro-mechanical energy conversion element via an insulating member. Ultrasonic actuator. 7. The ultrasonic actuator according to any one of claims 1 to 6, wherein the non-axisymmetric vibration generated in the elastic body has a peripheral order of 1.
An ultrasonic actuator characterized in that it is a non-axisymmetric vibration mode having a first-order mode number. 8. The ultrasonic actuator according to claim 7, wherein the bending vibration generated in the elastic body is a first-order bending vibration mode. 9. The ultrasonic actuator according to any one of claims 1 to 8, wherein the electro-mechanical energy conversion element has elasticity in a first direction and a second direction. An ultrasonic actuator, wherein two sets are provided on one side or both sides of a body.