JPH08182351A - Ultrasonic actuator - Google Patents

Abstract

PURPOSE: To provide an ultrasonic actuator which can one-or two-dimensionally move in a plane and can be easily incorporated in a cylindrical part. CONSTITUTION: An ultrasonic actuator is provided with an elastic body 11 composed of a hollow discoid elastic material, piezoelectric elements 21 and 22 which are joined to the elastic body 11, are excited by driving signals A and B, cause the elastic body 11 to generate expanding/contracting vibrations and flexural vibrations so that a prescribed part of the elastic body 11 can make elliptical motions, driving power fetching member 31 and 32 provided at prescribed parts of the elastic body 11, etc.

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 contraction of stretching 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 exciting an electromechanical conversion element, and a moving element which is in pressure contact with the elastic body ( Drive the rotor).

On the other hand, in a linear ultrasonic actuator, an electromechanical conversion element for vibration is arranged at one end of a rod-shaped elastic body, and an electric vibration absorber for absorbing reflection of traveling waves is arranged at the other end. The mechanical conversion element is arranged to generate a traveling wave from one of the elastic bodies to the other and drive the moving body that is in pressure contact with the elastic body.

[0004]

The former actuator is incorporated in the lens barrel and is rotated by the moving body to
It is used to drive the F lens. On the other hand, an image blur correction device has been proposed in which a part of the photographing optical system is moved in a plane substantially orthogonal to the optical axis to correct the image blur, but the former actuator cannot be applied because the driving direction is different. . In the latter actuator, it is difficult to incorporate in the cylindrical lens barrel, and in the X direction of the plane perpendicular to the optical axis, the Y direction.
In the case of driving in two directions, there is a problem that the device becomes large. Further, in the case of utilizing the conventional electromagnetic motor characterized by high speed and low torque, a gear train is usually required in order to obtain the output torque. Furthermore, when moving the driven object in two directions in a plane, In order to move the driven object in the direction of, another independent set of electromagnetic motor and gear train is required. For this reason, there have been problems that the device becomes large in size and weight, the responsiveness is lowered due to the gear train, and noise is generated.

An object of the present invention is to provide an ultrasonic actuator which can move in a plane in one dimension or two dimensions and can be easily incorporated into a cylindrical portion.

[0006]

In order to solve the above-mentioned problems, the invention of claim 1 is such that an elastic body made of an elastic material in the shape of a hollow disk is joined to the elastic body, and is driven by a drive signal. The electromechanical conversion element is excited to generate stretching vibration and bending vibration in the elastic body, and generate an elliptical motion in a predetermined portion of the elastic body due to its contraction.

According to a second aspect of the present invention, in the ultrasonic actuator according to the first aspect, the elastic body has the resonance frequencies of the stretching vibration and the bending vibration substantially equal to each other.
The feature is that the ratio of the outer diameter to the inner diameter is adjusted.

The invention of claim 3 relates to claim 1 or claim 2.
The ultrasonic actuator according to the aspect 1, is characterized in that a driving force extracting member is provided at the predetermined portion of the elastic body. According to a fourth aspect of the invention, in the ultrasonic actuator according to the third aspect, the contact portion of the driving force extracting member with the relative moving member is a curved body.

The invention of claim 5 is claim 3 or claim 4.
In the ultrasonic actuator according to the aspect 1, the driving force extracting member is joined to the surface of the electromechanical conversion element via an insulating member.

The invention according to claim 6 is the ultrasonic actuator according to any one of claims 1 to 5, wherein:
The elastic body is characterized in that primary bending vibration or secondary bending vibration is generated.

According to a seventh aspect of the invention, there is provided the ultrasonic actuator according to any one of the first to sixth aspects,
The electromechanical conversion element is arranged in a plurality of pieces on one surface of the elastic body, and is used by being grouped into a first direction and a second direction.

The invention of claim 8 is the ultrasonic actuator according to any one of claims 1 to 6, wherein:
The electromechanical conversion element is characterized in that the one for the first direction and the one for the second direction are separately provided on both surfaces of the elastic body.

The invention of claim 9 is the ultrasonic actuator according to any one of claims 1 to 6, wherein:
The electromechanical conversion element is characterized in that the one for the first direction and the one for the second direction are laminated on one surface of the elastic body.

[0014]

According to the present invention, when the electromechanical conversion element is excited, stretching and bending vibrations are generated in the hollow disk type elastic body, and due to the contraction, an elliptical motion is generated in a predetermined portion of the elastic body. Therefore, it becomes possible to move in the plane direction.

[0015]

【Example】

(First Embodiment) Hereinafter, the embodiments will be described in more detail with reference to the drawings. 1 to 5 are views showing a first embodiment of an ultrasonic actuator according to the present invention, FIG. 1 is a schematic view showing the entire structure, and FIG. 2 is a perspective view showing an elastic body and a piezoelectric element. FIG. 3 is a diagram illustrating an elastic body, FIG. 4 is a diagram illustrating a driving force extracting member, and FIG.
[Fig. 6] is a diagram for explaining the operation. This ultrasonic actuator includes an elastic body 11, two piezoelectric elements (electromechanical conversion elements) 21 and 22 joined to the upper surface of the elastic body 11, and four driving forces formed on the lower surface of the elastic body 11. Extracting member 31
.., etc.

As shown in FIG. 2, the elastic body 11 is a hollow disk type elastic member and is made of metal or plastic. As described with reference to FIG. 3, the elastic body 11 expands and contracts (R1 mode: spreading vibration in the surface direction) by setting the dimensions of the hollow disk.
And the second bending vibration (B ₂₁ mode) can be matched. In this embodiment, the holes inside the hollow disk are realized by adjusting the diameter.

The horizontal axis of FIG. 3 shows the ratio y = b / a of the outer diameter 2a and the inner diameter 2b (see FIG. 1) of the hollow disk. The holes get bigger as you get closer. The vertical axis represents the ratio of the resonance frequency ω ₀₀ of the R1 mode to the resonance frequency ω ₂₁ of the B ₂₁ mode, that is, ω ₂₁ / ω ₀₀ = {α ₂₁ ² /[2.05·
(3) ^1/3 ]} · (h / 2a).

Here, the curve (A) in FIG. 3 shows the R1 mode, and the curves (B), (C), and (D) show the case of the B ₂₁ mode, and h (of the disc) Thickness) / 2a,
It is different from 3/40, 2.5 / 40, and 2/40. As is clear from FIG. 3, the thickness h = 2.5 mm,
When the outer diameter 2a = 40 mm, degeneration is possible near y = 0.6. In this embodiment, an example in which the R1 mode and the B ₂₁ mode (second-order bending mode) are degenerated will be described.
The node 11a in the −B ₂₁ mode is shown in FIG.
It is shown in (A).

As shown in FIG. 2, the piezoelectric elements 21 and 22 have a semi-hollow disk shape and are made of PZT or the like. The piezoelectric elements 21 and 22 are polarized as shown in FIGS. 1A and 1C, and two-phase input voltages A and B are applied.

The driving force extracting members 31 to 34 are portions for extracting an elliptic motion generated by a combined vibration of the elastic body 1 including bending vibration and stretching vibration, and are fixed members 51 (relative moving members).
Move relative to it while touching. Driving force extracting members 31 to 3
As shown in FIG. 1 (A), 4 is the lower surface of the elastic body 1 and is provided at four positions on the outer edge portion thereof at intervals of 90 degrees.
The driving force extracting members 31 to 34 are attached with spherical bodies such as silicon nitride in order to improve wear resistance. In order to efficiently take out the driving force, these driving force taking-out members 31 to 34 are preferably provided avoiding the positions of the nodes of the longitudinal vibration, and the driving force taking-out members 31, 31-1, 31 shown in FIG.
-2, it is preferable to be at the antinode position of the vertical vibration generated in the bending vibration mode in a direction substantially perpendicular to the moving plane.

This ultrasonic actuator is shown in FIG.
As shown in FIG. 5, by applying high frequency voltages A and B to the two piezoelectric elements 21 and 22, a composite vibration of bending vibration and stretching vibration is caused, whereby the driving force extracting member 31,
An elliptic motion is generated at the tip of 32 to generate a driving force. Here, G is the ground. The two piezoelectric elements 21 and 22 are polarized so that the polarities thereof are in the same direction, and the high frequency voltages A and B are π / 2.
Has a temporal phase difference of. The two piezoelectric elements 2
The polarizations of 1 and 22 may be opposite to each other (see FIG. 6).

The oscillator 41, as shown in FIG.
It is for oscillating a high frequency signal, and its output is branched, one of which is converted into a signal having a time phase difference of π / 2 by a phase shifter 42, and then connected to an amplifier 43, and the other one. Are directly connected to the amplifier 44. The outputs of the amplifiers 43 and 44 are connected to the piezoelectric elements 21 and 22 as high frequency voltages A and B, respectively.

FIG. 5A shows the change over time of the two-phase high-frequency voltages A and B input to this ultrasonic actuator.
1 to t9. The horizontal axis of FIG. 5A indicates the effective value of the high frequency voltage. FIG. 5B shows how the cross section of the ultrasonic actuator is deformed, and shows a temporal change (t1 to t9) of bending vibration generated in the ultrasonic actuator. FIG. 5C shows how the cross section of the ultrasonic actuator is deformed, and shows the temporal change (t1 to t9) of the stretching vibration generated in the ultrasonic actuator.
FIG. 5D shows a temporal change (t1 to t) of the elliptic motion generated in the driving force extracting members 31 and 32 of the ultrasonic actuator.
9) 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. 5A, 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. 5B, the bending movements 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. 5C, the stretching vibration due to the high frequency voltages A and B is generated in the stretching 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. 5D, 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. 5 (A), the high frequency voltage B becomes zero and the high frequency voltage A generates a positive voltage. As shown in FIG. 5 (B), a bending motion is generated by the high frequency voltage A, the mass point Y1 oscillates in the negative direction, and the mass point Z1 oscillates in the positive direction. Further, as shown in FIG. 5C, the stretching vibration due to the high frequency voltage A is generated, and the mass point Y2
And the mass point Z2 shrink more than at time t1. as a result,
As shown in FIG. 5D, the both vibrations are combined, and the mass points Y and Z move counterclockwise as compared with the case of the time t1.

At time t3, as shown in FIG. 5A, 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. 5 (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 negative direction more than at the time t2, showing the maximum negative amplitude value. Mass point Z1 is time t2
It is amplified in the positive direction more than when, and shows the maximum positive amplitude value. Further, as shown in FIG. 5C, the stretching vibrations due to the high frequency voltages A and B cancel each other out, and the mass points Y2 and Z
2 and return to their original positions. As a result, as shown in FIG. 5 (D), both vibrations described above are combined, and the mass points Y and Z are time t2.
Move counterclockwise than when.

At time t4, the high frequency voltage A becomes zero and the high frequency voltage B generates a negative voltage as shown in FIG. 5 (A). As shown in FIG. 5 (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. 5 (C), stretching vibration due to the high frequency voltage B occurs, and the mass points Y2 and Z2 contract. As a result, as shown in FIG. 5 (D), both of the above vibrations are combined, and the mass points Y and Z move counterclockwise as compared with the time point t3.

At time t5, as shown in FIG. 5 (A), the high frequency voltage A generates a negative voltage, and the high frequency voltage B similarly generates the same negative voltage. As shown in FIG. 5B, the bending movements 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 stretching 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. 5 (D), both vibrations are combined, and the mass points Y and Z move counterclockwise as compared with the time point t4.

As the time t6 to t9 changes,
Bending vibrations and stretching vibrations are generated in the same manner as the above-mentioned principle, and as a result, as shown in FIG. 5D, the mass points Y and Z move counterclockwise to make an elliptic motion. Based on the above principle,
This ultrasonic actuator includes driving force extracting members 31, 3
An elliptical motion is generated at the tip of 2 and a driving force is generated. Therefore, when the tips of the driving force extracting members 31 and 32 are pressed against the fixed portion 51, the elastic body 11 is self-propelled with respect to the fixed portion 51.

FIG. 6 is a perspective view showing a modification of the piezoelectric element of the ultrasonic actuator according to the first embodiment. As shown in FIG. 2, the piezoelectric elements 21 and 22 are polarized in the same direction (upward), but in the example of FIG. 6, the piezoelectric element 21 is upward and the piezoelectric element 22-1 is downward. The polarization directions are different. In this case, the piezoelectric element 22- of FIG.
1 may apply a drive signal whose sign is inverted from that of the piezoelectric element 22 of FIG.

(Second Embodiment) FIGS. 7 to 9 are views showing a second embodiment of the ultrasonic actuator according to the present invention, and FIG. 7 is a schematic view showing the entire structure, and FIG. 9 is a perspective view showing a piezoelectric element, and FIG. 9 is a perspective view showing a modified example of the piezoelectric element. In each of the embodiments described below, the parts having the same functions as those of the first embodiment described above are designated by the same reference numerals, and the duplicated description will be appropriately omitted. In the second embodiment, the piezoelectric element 20 is formed by sticking two electrode plates 20a and 20b separately to one piezoelectric material. By doing so, it is not necessary to position the two piezoelectric elements, and the manufacturing becomes easy. That is, since the bonding and positioning of the piezoelectric element is easy, the elastic body 11 and the piezoelectric element 20 can be easily positioned.
The accuracy of adhesion is improved, the excitation unevenness caused by the displacement of the attachment position of the piezoelectric element is reduced, and the left-right difference (difference in the moving speed in the + x and -x directions) due to the difference in the moving direction is also reduced. In addition, the modification of FIG. 9 has two electrode plates 20.
The polarization direction of the piezoelectric material is different from that of the portions a and 20b.

(Third Embodiment) FIGS. 10 to 13 are views showing a third embodiment of the ultrasonic actuator according to the present invention, and FIG. 10 is a schematic view showing the entire structure, and FIG.
Is a perspective view showing the piezoelectric element, FIG. 12 is a view showing the arrangement of the piezoelectric element, and FIG. 13 is a perspective view showing a modified example of the piezoelectric element. The first and second embodiments have a structure capable of moving only in one dimension (X direction), but the third embodiment has a structure capable of moving in two dimensions (X direction and Y direction). is there.

The piezoelectric element 23 has a piezoelectric material in one direction [see FIG.
0 (B)], and as shown in FIGS. 11 and 12, the four electrode plates 23a, 23b, 23c, 23
It is divided into d. In addition, the driver circuit is shown in FIG.
As shown in FIG. 4, the high frequency signal from the oscillator 41 is branched, and one of them is connected to the X-direction phase shifter 42X and the Y-direction phase shifter 4.
After being phase-shifted by π / 2 by 2Y, the X-direction amplifier 43X and the Y-direction amplifier 43Y are connected to each other, and the other is directly connected to the X-direction amplifier 44X and the Y-direction amplifier 44Y. It is connected. Each amplifier 43X, 43
Y, 44X and 44Y are connected to the respective electrode plates 23a, 23b, 23c and 23d of the piezoelectric element via the changeover switch 45.

In the changeover switch 45, when all the contacts are switched to the X side (the state of the broken line in FIG. 10), the output of the amplifier 43X is connected to the electrode plates 23a and 23b, and the output of the amplifier 44X is It is connected to the electrode plates 23c and 23d. Therefore, since the left electrode plates 23a and 23b are grouped and the right electrode plates 23c and 23d are grouped, it becomes possible to move in the X direction as in the case of FIG. Similarly, in the changeover switch 45, when all the contacts are switched to the Y side (state of the solid line in FIG. 10), the output of the amplifier 43Y is connected to the electrode plates 23a and 23c, and the output of the amplifier 44Y is , Electrode plates 23b, 23
connected to d. Therefore, the upper electrode plates 23a, 2
Since 3c is grouped and the lower electrode plates 23b and 23d are grouped, the state shown in FIG. 7 is rotated by 90 °, and movement in the Y direction is possible.

Further, in particular, in this embodiment, the driving force extracting members 31 to 34 have a spherical shape or an ellipsoidal shape so that a uniform driving force can be obtained in the two directions of the X direction and the Y direction. It is preferably a part of the curved body.

Also in the case of the third embodiment, since the bonding and positioning of the piezoelectric element is facilitated, the excitation unevenness is reduced and the left-right difference (+ x) due to the difference in the moving direction is the same as in the second embodiment. , -X direction, + y, -y direction moving speed difference)
Is also reduced. In the modification of FIG. 13, the piezoelectric element 23 has four piezoelectric elements 23-1, 23-2, 23-3, 2 respectively.
It is divided into 3-4.

(Fourth Embodiment) FIGS. 14 to 17 are views showing a fourth embodiment of the ultrasonic actuator according to the present invention, and FIG. 14 is a schematic view showing the entire structure, and FIG.
FIG. 16 is a perspective view showing a piezoelectric element, and FIGS. 16 and 17 are views showing the arrangement of driving force extracting members, respectively. In the third embodiment, switching is performed by grouping the four-divided piezoelectric elements into groups for the X direction and the Y direction so that the piezoelectric elements can be moved two-dimensionally (X direction and Y direction). In the example, the elastic body 11 is provided with piezoelectric elements for the X direction and for the Y direction separately on both surfaces.

As shown in FIG. 15, the piezoelectric elements 24-1 and 24-2 for the X direction are arranged on the upper surface of the elastic body 11, and the piezoelectric elements 25-1 and 25-2 for the Y direction are arranged. , Is disposed on the lower surface of the elastic body 11.

The drive circuit, as shown in FIG.
A high-frequency signal from the oscillator 41 is passed through the changeover switch 46 to drive the X-direction drive circuit (phase shifter 42X, amplifier 43).
X, 44X) and a drive circuit for the Y direction (phase shifter 42Y,
It is connected to the amplifiers 43Y and 44Y). Each amplifier 4
3X, 43Y, 44X, 44Y are connected to the respective piezoelectric elements 24-1, 24-2, 24-3, 2 via the changeover switch 46.
It is connected to 4-4.

The changeover switch 46 has a contact on the X side (see FIG. 14).
(State of the broken line of), the amplifier 43
The output of X is connected to the piezoelectric element 24-1, and the amplifier 44
Since the output of X is connected to the piezoelectric element 24-2, it can be moved in the X direction.

The contact of the changeover switch 46 is on the Y side (see FIG. 14).
(Solid line state of), the amplifier 43
The output of Y is connected to the piezoelectric element 25-1 and the amplifier 44
Since the Y output is connected to the piezoelectric element 25-2, it can be moved in the Y direction.

In this embodiment, the piezoelectric element 25 is the elastic body 1.
Since it is also provided on the lower surface of 1, the driving force output 32 is
Since it is arranged at a position straddling the two piezoelectric elements 25-1 and 25-2, as shown in FIG. 16, it is mounted via a mounting member 35 made of an insulating material such as fine ceramics. . In addition, FIG.
As shown in (B), the piezoelectric elements 24 and 25 are attached to the mounting member 3
It is attached directly to the elastic body 11 by making the radius smaller by the width of 5, or by making the interval between the piezoelectric elements 25-1 and 25-2 wider than the size of the driving force extracting member 32, as shown in FIG. 17 (C). You may do it. Further, as shown in FIG. 17D, the mounting member 36 may be extended to the outside of the elastic body 11 and the driving force extracting members 31 to 14 may be mounted to the mounting member 36.

In the fourth embodiment, a plurality of piezoelectric elements are used. Therefore, piezoelectric elements having the same polarization (poling) state can be selected to form a piezoelectric element group having less unevenness in each sector as a whole. There are advantages. The same applies to FIG. 6 of the first embodiment and FIG. 13 of the third embodiment.

(Fifth Embodiment) FIGS. 18 and 19 are views showing a fifth embodiment of the ultrasonic actuator according to the present invention. FIG. 18 is a developed perspective view showing the arrangement of piezoelectric elements. 19 is a partially enlarged view of FIG. 18. In the fourth embodiment, the X-direction piezoelectric element and the Y-direction piezoelectric element are separately provided on both sides of the elastic body 11, but in the fifth embodiment, the X-direction and Y-direction piezoelectric elements are provided on the upper surface of the elastic body 11. The piezoelectric elements are arranged one above the other.

The piezoelectric element 27 for the Y direction is bonded to the upper surface of the elastic body 11 and is an electrode plate 28YA, 2 such as a copper plate.
Piezoelectric materials 27A-1 and 27B-1 and piezoelectric materials 27A-2 and 27B-2 are laminated with 8YB sandwiched therebetween. The piezoelectric element 26 for the X direction is the piezoelectric element 2 for the Y direction.
7 is bonded via the electrode plate 28-1 to the piezoelectric material 26A-1, and the electrode plates 28XA and 28XB are sandwiched therebetween.
26B-1 and the piezoelectric materials 26A-2 and 26B-2 are laminated, and the electrode plate 28-2 is joined to the upper surface thereof. The polarization direction of each piezoelectric material is as shown in FIG.
Electrode plates 28XA, 28XB and electrode plates 28YA, 28Y
B is connected to the X-direction input and the Y-direction input, respectively, and is connected to the electrode plates 28-1 and 28-2 and the elastic body 11.
Is connected to ground. According to the fifth embodiment, since the number of piezoelectric materials increases, there is an advantage that a large driving force can be obtained.

(Sixth Embodiment) FIG. 20 is a schematic diagram showing the entire structure of a sixth embodiment of the ultrasonic actuator according to the present invention. The sixth embodiment has almost the same structure as the second embodiment shown in FIG. 7, but the second embodiment has R1.
Whereas there was a -B ₂₁ mode shows the case of R1-B ₁₁ mode (first-order bending). Section 11b of the R1-B ₁₁ mode is shown in FIG. 20 (A).

(Seventh Embodiment) FIG. 21 is a schematic diagram showing the entire structure of a seventh embodiment of the ultrasonic actuator according to the present invention. The seventh embodiment is similar to the third embodiment shown in FIG.
The configuration is almost the same as that of the third embodiment, but the third embodiment is
1- _B21X - _B21Y mode, while R1-
The case of _B11X - _B11Y (first-order bending) is shown. The node 11b at this time is shown in FIG. 6, as in the seventh _{embodiment, R1-B 11, R1-} B 11X
In the -B _11Y mode, R1-B ₂₁ , R1-B _21X -B _21Y
As compared with the case of the mode, the size of the elastic member when the vibration of the R1 mode and B ₁₁ mode is degenerate becomes thicker thin circle plate. Therefore, in these examples, due to constraints such as the dimensions to be incorporated in the object to be driven, when it is desired to increase the inner diameter with respect to the outer diameter, that is, to make the hollow portion as large as possible,
Is suitable.

(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, although the electromechanical conversion element is described as an example of a piezoelectric element, 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 plotter sheet feeding device, and the like.

[0050]

As described above in detail, according to the present invention, the vibration of the electromechanical conversion element causes expansion and contraction vibration and bending vibration in the hollow disk type elastic body, and the elastic body is contracted to cause the elastic body. Since an elliptical motion is generated in a predetermined part of the above, it is possible to move in the plane direction, so that one-dimensional or two-dimensional driving is easy, and furthermore, it can be easily incorporated in a cylindrical part or the like.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the overall configuration of a first embodiment of an ultrasonic actuator according to the present invention.

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

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

FIG. 4 is a diagram for explaining a driving force extracting member of the ultrasonic actuator according to the first embodiment.

FIG. 5 is a diagram illustrating the operation of the ultrasonic actuator according to the first embodiment.

FIG. 6 is a perspective view showing a modification of the piezoelectric element of the ultrasonic actuator according to the first embodiment.

FIG. 7 is a schematic diagram showing the overall configuration of a second embodiment of the ultrasonic actuator according to the present invention.

FIG. 8 is a perspective view showing a piezoelectric element of an ultrasonic actuator according to a second embodiment.

FIG. 9 is a perspective view showing a modification of the piezoelectric element of the ultrasonic actuator according to the second embodiment.

FIG. 10 is a schematic diagram showing the overall configuration of a third embodiment of the ultrasonic actuator according to the present invention.

FIG. 11 is a perspective view showing a piezoelectric element of an ultrasonic actuator according to a third embodiment.

FIG. 12 is a diagram showing an arrangement of piezoelectric elements of an ultrasonic actuator according to a third embodiment.

FIG. 13 is a perspective view showing a modified example of the piezoelectric element of the ultrasonic actuator according to the third embodiment.

FIG. 14 is a schematic diagram showing the overall configuration of a fourth embodiment of the ultrasonic actuator according to the present invention.

FIG. 15 is a perspective view showing a piezoelectric element of an ultrasonic actuator according to a fourth embodiment.

FIG. 16 is a diagram showing an arrangement of driving force extracting members of an ultrasonic actuator according to a fourth embodiment.

FIG. 17 is a diagram showing an arrangement of driving force extraction members of an ultrasonic actuator according to a fourth embodiment.

FIG. 18 is a developed perspective view showing the arrangement of piezoelectric elements of a fifth embodiment of the ultrasonic actuator according to the present invention.

FIG. 19 is a partially enlarged view of FIG. 18.

FIG. 20 is a schematic diagram showing the overall configuration of a sixth embodiment of the ultrasonic actuator according to the present invention.

FIG. 21 is a schematic diagram showing the overall configuration of a sixth embodiment of the ultrasonic actuator according to the present invention.

[Explanation of symbols]

 11 Elastic body 21, 22, 23, 24, 25, 26, 27 Piezoelectric element 31, 32, 33, 34 Driving force extracting member 35, 36 Mounting member 41 Oscillator 42 Phase shifter 43, 44 Amplifier 45, 46 Changeover switch 51 Fixed member

Claims (9)

[Claims] 1. A hollow disk-shaped elastic body made of an elastic material, and an elastic body that is joined to the elastic body and is excited by a drive signal to generate stretching vibration and bending vibration in the elastic body, and degenerate it. An ultrasonic actuator including an electromechanical conversion element that generates an elliptical motion in a predetermined portion of the elastic body. 2. The ultrasonic actuator according to claim 1, wherein the elastic body has a ratio of an outer diameter and an inner diameter thereof adjusted so that resonance frequencies of the stretching vibration and the bending vibration substantially match with each other. An ultrasonic actuator characterized by the above. 3. The ultrasonic actuator according to claim 1, wherein a drive force extracting member is provided on the predetermined portion of the elastic body. 4. The ultrasonic actuator according to claim 3, wherein a contact portion of the driving force extracting member with the relative moving member is a curved body. 5. The ultrasonic actuator according to claim 3 or 4, wherein the driving force extracting member is joined to a surface of the electromechanical conversion element via an insulating member. Actuator. 6. The ultrasonic actuator according to claim 1, wherein the elastic body generates a primary bending vibration or a secondary bending vibration. Sonic actuator. 7. The ultrasonic actuator according to claim 1, wherein the electromechanical conversion element is divided into a plurality of pieces and arranged on one surface of the elastic body. , An ultrasonic actuator characterized in that the ultrasonic actuators are grouped and used for the first direction and the second direction. 8. The ultrasonic actuator according to any one of claims 1 to 6, wherein the electromechanical conversion element has a first direction and a second direction on both sides of the elastic body. An ultrasonic actuator, which is provided separately. 9. The ultrasonic actuator according to claim 1, wherein the electromechanical conversion element includes one of the elastic body for the first direction and one for the second direction. An ultrasonic actuator characterized by being laminated on a surface.