JPH0965671A - Vibration actuator - Google Patents

Abstract

(57) [Summary] [Problem] In the variant mode degenerate type vibration actuator proposed in Japanese Patent Application No. 6-275022, it is difficult to reduce the accommodation space and the driving efficiency is lowered. there were. SOLUTION: In a variant mode degenerate vibration actuator 20 proposed in Japanese Patent Application No. 6-275022, electrode overhanging portions 24a, 25a, 26a of electrodes 24, 25, 26 sandwiched by a vibrator 21 are Drive surface 2
It was arranged on the end face side facing 1a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration actuator provided with an elastic body for generating a driving force on an end surface thereof and a relative movement member which is in pressure contact with the elastic body and is rotatably supported.

[0002]

2. Description of the Related Art FIG. 8 is a perspective view showing the configuration of a conventional example of a longitudinal-torsion vibration type vibration actuator.

Conventionally, in this type of vibration actuator,
The stator (stator) 101 includes two cylindrical vibrators 1.
A piezoelectric element 104 for torsional vibration is arranged between 02 and 103, and a piezoelectric element 105 for longitudinal vibration is arranged above the vibrator 103. The piezoelectric element 104 for torsional vibration is polarized in the circumferential direction, while the piezoelectric element 105 for longitudinal vibration is polarized in the thickness direction. Furthermore, the rotor (moving element) 10
6 is arranged above the piezoelectric element 105 for longitudinal vibration.

A vibrator 102 constituting a stator 101,
103 and the piezoelectric elements 104 and 105
The rotor 106 is rotatably provided on the shaft 107 via a ball bearing 108 by being screwed and fixed to the threaded portion of the. A nut 110 is screwed onto the tip of the shaft 107 via a spring 109 to bring the rotor 106 into pressure contact with the stator 101 with a pressing force F.

The piezoelectric element 104 for torsional vibration and the piezoelectric element 105 for longitudinal vibration are driven by phase-shifting a voltage of the same frequency oscillated from an oscillator 111 by a phase shifter 112.

The piezoelectric element 104 for torsional vibration is the rotor 1
06 provides a mechanical displacement for rotation, while the piezoelectric element 105 for longitudinal vibration periodically synchronizes the frictional force acting between the stator 101 and the rotor 106 with the cycle of torsional vibration by the piezoelectric element 104. By virtue of this, it plays the role of a clutch that converts vibration into movement in one direction.

FIG. 9 is a perspective view showing the stator of this vibration actuator in a developed state. Since the piezoelectric element 104 for torsional vibration needs to be polarized in the circumferential direction, the piezoelectric material is once divided into about 6 to 8 fan-shaped small pieces as shown in FIG. It was combined in a ring. Reference numeral 104a is an electrode.

[0008]

However, as shown in FIG. 8 and FIG.
In the conventional vibration actuator described by using, it is difficult to obtain the shape accuracy when the piezoelectric element 104 for torsional vibration is combined in an annular shape.

On the other hand, the areas of the piezoelectric element 105 for longitudinal vibration and the piezoelectric element 104 for torsional vibration are both
It was substantially equal to or smaller than the cross-sectional area of the stator 106. Also, the shaft 10
It is also necessary to make a hole in the central portion of each of the piezoelectric element 105 for longitudinal vibration and the piezoelectric element 104 for torsional vibration in order to penetrate the piezoelectric element 7. Therefore, the piezoelectric element 10 for longitudinal vibration is provided.
5, the area of each of the piezoelectric elements 104 for torsional vibration is further reduced, and it has been difficult to achieve both high torque and high rotation of the vibration actuator.

In order to solve such a problem, the applicant of the present invention has already proposed, in Japanese Patent Application No. 6-275022, a variant which can be driven with a high torque and a high rotation and is easy in structure and manufacturing. A mode degenerate vibration actuator is proposed.

FIG. 10 is a sectional view showing the structure of this variant mode degenerate vibration actuator, and FIG. 11 is a perspective view showing the structure of the vibrator used in this vibration actuator.

In FIG. 10, on the outer peripheral surface of a rod-shaped fixed shaft 1 having a large diameter portion 1a in the center, a vibrator 2 which is a cylindrical elastic body is attached with a mounting bolt 3a which is screwed into the large diameter portion 1a. ，
It is penetrated by 3b.

As shown in FIG. 11, the vibrator 2 is constructed by combining two thick semi-cylindrical elastic bodies 2a and 2b, and the joint surface thereof has a torsional vibration with a large piezoelectric constant d _15. The piezoelectric elements 4 and 4 for vertical vibration and the piezoelectric elements 5 and 5 for vertical vibration having a large piezoelectric constant d ₃₁ are sandwiched by two pieces, respectively, four pieces in total. Note that the semi-cylindrical elastic bodies 2a and 2b may be semi-cylindrical elastic bodies unlike the example of this figure.

As shown in FIG. 10, a moving surface D, which is the upper end surface of the vibrator 2, is a relative motion member rotatably arranged on the fixed shaft 1 by a bearing 6 arranged at the center. The child 7 contacts.

The mover 7 includes a mover base material 7a and an elastic body 2.
And a sliding member 7b that comes into contact with the driving surface D, and is positioned with respect to the fixed shaft 1 by a bearing 6 fitted to the inner peripheral portion.

The moving element 7 is pressed against the driving surface D of the elastic body 2 by a pressing member 8 such as a disc spring, a spring spring, or a leaf spring. In this way, the fixed shaft 1 fixes the vibrator 2 made of an elastic body or the like and positions the moving element 7 rotatably in the radial direction to prevent the occurrence of shaft run-out when driving as a vibration actuator. This fixed shaft 1
Has a threaded portion 1b formed at its tip, and an adjusting member 9 such as a nut for adjusting the amount of pressurization of the pressurizing member 8 is screwed.

The vibration actuator configured as described above is excited by applying a drive voltage from a drive voltage generator (not shown) to each of the piezoelectric elements 4 and 5, and the vibrator 2 is tuned for torsional vibration and longitudinal vibration. Occurring in a sudden way. When the resonance frequencies of torsional vibration and longitudinal vibration are approximately the same,
Torsional vibration and longitudinal vibration occur at the same time (degenerate), and an elliptic motion is generated on the drive surface D. The elliptic motion serves as a driving force to rotationally drive the moving element 7 in pressure contact.

As shown in FIG. 11, since a driving voltage is applied to the piezoelectric elements 4 and 5, electrodes 10 and 1 are provided between the piezoelectric elements.
1, 12 are sandwiched, but in order to apply a drive voltage to the electrodes 10, 11, 12 from an external drive voltage generator (not shown), it is on the side surface of the vibrator 2 in the elastic body central axis direction. Piezoelectric elements 4 and 5 so as to protrude near the central portion
A rectangular electrode overhanging portion 10 is provided at each substantially central portion in the longitudinal direction.
a, 11a, 12a are provided. Then, lead wires (not shown) connected to the drive voltage generator are connected to these electrode extension portions 10a, 11a, 12a.

However, as a result of further study by the present inventor, it was found that the variant mode degenerate vibration actuator shown in FIGS. 10 and 11 has the following problems.

That is, in recent years, with the miniaturization of electronic information devices, there is an extremely strong demand for mounting an actuator in a space as small as possible. In response to such a request, this variant mode degenerate type vibration actuator is suitable for use in a narrow space because the elastic body can have a cylindrical or columnar shape to have a slender structure by design. Further, the variant mode degeneration type vibration actuator is small in size and does not require a complicated speed reducing mechanism because high torque can be obtained. From this point of view as well, it is suitable for a small device.

However, in the variant mode degenerate type vibration actuator shown in FIGS. 10 and 11, the electrode overhanging portion 1 is used.
Since 0a, 11a, 12a and the lead wire are arranged so as to project outward in the radial direction of the vibrator 2, for example, to be mounted on the electronic information device described above, at least the vibrator should be mounted on the electronic information device. It is necessary to secure a storage space larger than the diameter of 2.

Further, in FIG. 11, the electrode overhanging portion 10
Since a, 11a, and 12a exist in the portion where the shearing force due to the torsional vibration mode generated in the vibrator 2 acts, the torsional vibration that directly contributes to the driving force of the vibration actuator is attenuated, and the vibration actuator is driven. There was also a risk that it would reduce efficiency.

Further, when the vibration actuator is mounted in the above-mentioned housing space, it is necessary to take measures to surely prevent a short circuit due to contact of each electrode. As described above, the variant mode degenerate type vibration actuator previously proposed by the present applicant in Japanese Patent Application No. 6-275022 is:
There are problems that it is difficult to reduce the size of the accommodation space and that the driving efficiency is reduced, and in addition to these problems, there is also a problem that a short circuit easily occurs due to contact between electrodes.

[0024]

According to a first aspect of the present invention, a plurality of electro-mechanical energy conversion elements excited by drive signals and electrodes sandwiched between the electro-mechanical energy conversion elements are laminated. While holding in the state,
A vibration actuator comprising: an elastic body that generates a driving force on a driving surface, which is an end surface; and a relative movement member that is in pressure contact with the elastic body and is rotatably supported. It is characterized in that it has an electrode overhanging portion for applying a voltage from the outside on the opposing end face side.

According to a second aspect of the present invention, in the vibration actuator according to the first aspect, the electrode projecting portions are arranged at positions where they do not contact each other.

The invention of claim 3 is the same as claim 1 or claim 2.
In the vibration actuator described in [1], longitudinal vibration and torsional vibration are generated in the elastic body, and a driving force is generated on the driving surface.

According to the vibration actuator of any one of claims 1 to 3, since the electrode overhanging portion is provided on the end surface of the vibrator facing the driving surface, the diameter of the vibrator is reduced. The electrode protrusion and the lead wire do not project outward in the direction. Therefore, the accommodation space of the vibration actuator only needs to have substantially the same size as the outer diameter of the vibrator, and a space-saving vibration actuator is realized.

Further, since the electrode overhanging portion is arranged on the end face farthest from the driving surface of the vibrator, the vibration generated on the driving surface is not hindered.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 is an exploded perspective view of a vibration actuator according to a first embodiment of the present invention, and FIG. 2 is an exploded perspective view of a vibrator. Further, FIG. 3 is an explanatory view showing the arrangement of the piezoelectric elements sandwiched by the vibrators, FIG. 3 (A) is a top view seen from the drive surface 21a side, and FIG. 3 (B) is a front view.

The vibration actuator 20 of the first embodiment
Includes a vibrator 21 that is a cylindrical elastic body, and a mover 22 that is a cylindrical relative motion member that comes into pressure contact with the end surface 21a of the vibrator 21.

The vibrator 21 is composed of two semi-cylindrical elastic bodies 21.
b and 21c, and two piezoelectric elements 23 sandwiched between them, a total of four piezoelectric elements 23 for generating a torsional vibration having a large piezoelectric constant d _15.
a, a one by two total four piezoelectric elements 23b of the piezoelectric constant d ₃₁ is greater for longitudinal vibration generated composed of electrodes 24, 25, 26 and connected to each of the piezoelectric elements 23a, 23b.

The semi-cylindrical elastic bodies 21b and 21c are made of an elastic material such as metal or plastic, and a cylindrical body made of these materials is used as a plane including the rotation axis thereof.
It is manufactured by dividing.

The piezoelectric elements 23a and 23b are both electro-mechanical energy conversion elements that convert electric energy into mechanical displacement (mechanical energy), and are formed in a thin plate shape by PZT (lead zirconate titanate) or the like. .

As shown in FIG. 2, the electrodes 24, 25, and 26 are rectangular flat plate-shaped electrodes, and their short sides are connected to lead wires connected to a drive voltage generator (not shown). Rectangular plate-shaped electrode overhanging portions 24a, 25 for
a and 26a are projected.

The electrode 24 is an electrode for applying a driving voltage for torsional vibration for applying a driving voltage to the piezoelectric element 23a, and the electrode 26 is for longitudinal vibration for applying a driving voltage to the piezoelectric element 23b. The electrode 25 is an electrode for applying a driving voltage, and the electrode 25 is an electrode for installation. In this embodiment, copper electrodes are used as these electrodes.

In this embodiment, the electrode protrusions 24a, 25
Since a and 26a are provided so as to project from the end surface of the vibrator 21 opposite to the drive surface, the electrode overhanging portions 24a, 25a and 2a are formed.
6a and the lead wire (not shown) do not project. Therefore, the accommodation space when accommodating the vibration actuator 20 in, for example, an electronic information device may have a size substantially the same as the outer diameter of the vibrator 21, and is a small space type.

Further, since the electrode overhanging portions 24a, 25a, 26a are arranged on the end face of the vibrator 21 farthest from the drive surface 21a, the present applicant does not interfere with the vibration generated on the drive surface 21a. The driving efficiency can be improved as compared with the variant mode degenerate vibration actuator proposed in Japanese Patent Application No. 6-275022.

In the vibrator 21, the piezoelectric elements 23a and 23b and the electrodes 24, 25 and 26 are alternately laminated as shown in FIGS. 1 to 3, and these are sandwiched by the semi-cylindrical elastic bodies 21b and 21c. Then, they are assembled by bonding them.

The moving element 22 is usually a cylindrical body made of the same material as the vibrator 21, and the end face on the side contacting the vibrator 21 has
A disk-shaped sliding member 27 is attached to reduce the sliding resistance with the vibrator 11.

Next, the driving principle of the vibration actuator 20 which combines the torsional vibration and the longitudinal vibration of the vibrator 21 to generate an elliptic motion on the driving surface 21a will be described with reference to FIG.

In the figure, the vibrator 21 has a cylinder vertically arranged in two.
It has a shape divided into two parts, and the piezoelectric element 23 is formed on the divided surface.
It sandwiches a and 23b. Piezoelectric elements 23a, 23b
Is composed of two groups as described above, and includes the piezoelectric elements 23a, 2a.
The groups 3b each consist of 4 layers. Two layers from the piezoelectric element 23a for torsional vibration generating large piezoelectric constant d _15,
The remaining two layers and a piezoelectric element 23b for longitudinal vibration generating large piezoelectric constant d _31.

The former piezoelectric element 23 having a large piezoelectric constant d ₁₅
a generates shear displacement in the longitudinal direction of the vibrator 21. The piezoelectric elements 23a are arranged such that the shear deformation alternates between the front direction and the opposite direction with respect to the circumferential direction in the drawing viewed from the drive surface 21a. When the piezoelectric element 23b is sheared and deformed in such an arrangement, a torsional displacement is generated in the vibrator 21, and the drive surface 21a is twisted.

The latter piezoelectric element 23 having a large piezoelectric constant d ₃₁
For b, expansion and contraction displacement occurs in the longitudinal direction of the vibrator 21. The four longitudinal vibration piezoelectric bodies 23b are arranged in consideration of the polarization direction so that when the same potential is applied to the electrodes for the longitudinal vibration piezoelectric body, displacement occurs in the same direction (extension or contraction direction).

As described above, when the piezoelectric element 23a for torsional vibration having a large piezoelectric constant d ₁₅ and the piezoelectric element 23b having a large piezoelectric constant d ₃₁ are arranged, a sinusoidal voltage is input to the piezoelectric body 23a for torsional vibration. As a result, the oscillator 21 causes a torsional motion in response thereto, and when the sine wave voltage is input to the piezoelectric element 23b for longitudinal vibration, the oscillator 21 expands and contracts.

The drive circuit of the vibration actuator 20 of this embodiment is constructed as shown in FIG. That is, the drive circuit includes an oscillator 31 that oscillates a drive signal and a phase shifter 32 that divides the drive signal into signals having a 1 / 2π phase difference.
And a T amplification unit 33 that amplifies the drive signal input to the piezoelectric element 23a for torsional vibration, and an L amplification unit 34 that amplifies the drive signal input to the piezoelectric element 23b for longitudinal vibration.

The control circuit has a detecting section 3 for detecting torsional vibration.
5 and a control unit 36 that controls the frequency and voltage of the oscillation unit according to the detection amount of the detection unit 35. Detector 35
Is a mechanical-electrical energy conversion element (reference numeral 2 in FIG. 1) attached to the bottom surface of the vibrator 21 opposite to the drive surface 21a.
4c), the torsional displacement can be indirectly detected by detecting the voltage generated in the mechanical-electrical energy conversion element due to the generated torsion. In this way, the detection unit 35 detects the torsional vibration of the vibrator 21 by the voltage. The drive speed and drive torque of the mover 22 are estimated based on the value of this voltage.

The control unit 36 controls the drive frequency and voltage of the vibrator 21 according to the detection result of the detection unit 35. For example,
When the detected amount is larger than a predetermined value, the drive frequency is increased or the voltage is decreased. On the other hand, if the detected amount is smaller than the predetermined value, lower the drive frequency,
Increase the voltage.

Next, referring to FIG. 5, in the vibration actuator of the present embodiment, it is explained with time that an elliptic motion is generated on the drive surface by combining the longitudinal vibration and the torsional vibration generated in the vibrator 21. To do.

As shown in FIG. 4, when the phase difference between the period of the torsional vibration and the period of the stretching vibration is shifted by π / 2, an elliptic motion occurs at a fixed point on the driving surface. At time t = (6/4) π, the displacement of the torsional vibration T is maximum on the left side, while the displacement of the longitudinal vibration T is zero. In this state, the mover 22
The driving surface 21a of the vibrator 21 is brought into pressure contact with the pressure mechanism described later.

From this state, t = (7/4) π˜0
Up to (2/4) π, the torsional vibration T is displaced from the left maximum to the right maximum, while the longitudinal vibration T is displaced from zero to the upper maximum and returns to zero again. Therefore, the fixed point of the drive surface 21 a of the vibrator 21 rotates to the right while pushing the mover 22, and the mover 22 is driven.

Next, from t = (2/4) π to (6/4) π, the torsional vibration T is displaced from the maximum on the right side to the maximum on the left side, while the longitudinal vibration T is from zero to below. It shifts to the maximum on the side and returns to zero again. Therefore, the fixed point of the drive surface 21 a of the vibrator 21 rotates leftward while moving away from the moving element 22, so that the moving element 22 is not driven. At this time, mover 2
No. 2 does not follow the contraction of the vibrator 21 because the natural frequency is different even if it is pressed by the pressing member.

[0052] resonance frequency f _0T of the torsional vibration T, and the approximate expression of the resonance frequency f _0L of the longitudinal vibration L shown by the following formula and formula.

Resonance frequency of torsional vibration T f _0T = 1 / 2L _s · (G / ρ) ^1/2 ··· Resonance frequency of longitudinal vibration L f _0L = 1 / 2L _s · (E / ρ ) ^1/2 ..., where L _{s is} the length of the oscillator in the longitudinal direction, E is the longitudinal elastic modulus, G is the lateral elastic modulus, and ρ is the density.

According to the equations and the equations, the resonance frequencies of two vibrations do not match when the elastic body has a simple cylindrical or cylindrical shape. However, the resonance frequency of the longitudinal vibration is influenced by the length of the moving element, but the torsional vibration is not affected, so that the two resonance frequencies can be brought close to each other by adjusting the length of the moving element. Further, since the resonance frequency of the longitudinal vibration changes due to the influence of pressurization rather than the torsional vibration, the resonance frequency of the torsional vibration can be brought closer to the resonance frequency of the longitudinal vibration by adjusting the applied pressure.

The vibration actuator 20 of the present embodiment configured as described above is supported as shown in FIG. That is, in FIG.
On the outer peripheral surface of the rod-shaped fixed shaft 41 having a, the vibrator 21 which is a cylindrical elastic body is pierced by the mounting bolts 42a and 42b screwed to the large diameter portion 41a.

As shown in FIG. 6, the driving surface 21a, which is the upper end surface of the vibrator 21, is moved as a relative motion member rotatably arranged on the fixed shaft 41 by a bearing 43 arranged at the center. The child 22 contacts.

A sliding member 27 that contacts the driving surface 21a of the vibrator 21 is attached to the bottom surface of the mover 22, and is positioned with respect to the fixed shaft 41 by the bearing 43 fitted to the inner peripheral portion. It

The mover 22 is pressed against the driving surface 21a of the vibrator 21 by a pressing member 44 such as a disc spring, a spring spring or a leaf spring. In this way, the fixed shaft 4
1 fixes the vibrator 21 and positions the mover 22 rotatably in the radial direction to prevent the occurrence of shaft runout when driving as a vibration actuator. This fixed shaft 4
In No. 1, a screw portion 41b is formed at the tip, and an adjusting member 45 such as a nut for adjusting the amount of pressurization of the pressurizing member 44 is screwed.

The vibration actuator 20 configured as described above is excited by applying a drive voltage from a drive voltage generator (not shown) to each of the piezoelectric elements 23a and 23b, and the vibrator 21 receives torsional vibration and longitudinal vibration. It occurs in harmony. When the resonance frequencies of the torsional vibration and the longitudinal vibration are substantially the same, the torsional vibration and the longitudinal vibration occur at the same time (degenerate), an elliptical motion is generated on the drive surface 21a, and this elliptic motion serves as a driving force to make a pressure contact. The mover 22 is rotationally driven.

(Second Embodiment) FIG. 7 shows a second embodiment of the present invention.
It is a perspective view showing the structure of the vibrator used for the vibration actuator of the embodiment. In the following description of the present embodiment, only parts different from the first embodiment will be described, and common parts are denoted by the same reference numerals in the drawings, and the description thereof will be omitted.

As shown in FIG. 7, in the present embodiment, the electrode overhanging portions 24-1a, 25-1a, 26-1a are all end faces of the vibrator 21 facing the drive face 21a. The electrode protrusions 24-1a are installed so as to protrude to the side, but in order to prevent contact with each other, a distance longer than the electrode protrusion portion distance in the diameter direction in the diametrical direction of the end faces. , 25-1a and 26-1a are arranged so as to be offset from each other.

Therefore, the electrode protrusions 24-1a, 25
Even when the -1a and 26-1a are bent, the electrode protruding portions 24-1a, 25-1a and 26-1a are prevented from coming into contact with each other, and the short circuit of the vibration actuator 20 is eliminated.

In the first embodiment, the electrode protruding portion 24-1
a, 25-1a, 26-1a need to be prevented from contacting each other. For example, an insulator is provided inside the vibration actuator accommodating case, or a space is provided in the vibration actuator accommodating case. Although it was necessary to devise, in the present embodiment, such a need is eliminated, and it is possible to improve the performance of the vibration actuator and reduce the manufacturing cost.

(Modification) In the first and second embodiments, the means for detecting vibration by the piezoelectric elements 23a and 23b provided on the vibrator 21 is used, but the means is not limited to this. For example, a method of directly detecting the rotation speed by an encoder or the like and transmitting the detection result to the control unit 36 may be used.

In the first and second embodiments, the piezoelectric element is used as the electric-mechanical energy conversion element.
The present invention is not limited to this, as long as it can convert electrical energy into mechanical displacement (mechanical energy). Other than the piezoelectric element, for example, an electrostrictive element or a magnetostrictive element can be exemplified. Further, the shape of the elastic body forming the vibrator is not limited to the cylindrical shape,
For example, it may be a quadrangular prism.

Further, although the first and second embodiments have been described by taking the case where the torsional first-order mode vibration and the longitudinal first-order mode vibration occur in the vibrator 21, as an example, the present invention is not limited to this mode. is not. That is, the oscillator 21 has a twisting m-th order vibration mode (m: a natural number of 1 or more).
The present invention is equally applicable as long as a vibration mode of the nth order and a vibration mode (n is a natural number of 1 or more) are generated.

[0067]

In the vibration actuator according to the present invention, since the electrode overhanging portion is provided on the end face of the vibrator facing the driving surface, the electrode overhanging part and the electrode overhanging part are formed radially outward of the vibrator. Lead wire does not stick out. Therefore, if the accommodation space of the vibration actuator is approximately the same as the outer diameter of the vibrator, the vibration actuator can be accommodated, and a space-saving vibration actuator is realized.

Further, since the electrode overhanging portion is arranged on the end face farthest from the drive surface of the vibrator, the vibration generated on the drive surface is not hindered.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a vibration actuator according to a first embodiment.

FIG. 2 is an exploded perspective view of a vibrator of the vibration actuator according to the first embodiment.

FIG. 3 is an explanatory diagram showing an arrangement of piezoelectric elements sandwiched by the vibrators of the vibration actuator according to the first embodiment.
FIG. 3A is a top view seen from the driving surface side, and FIG. 3B is a front view.

FIG. 4 is an explanatory diagram showing a drive circuit of the vibration actuator of the present embodiment.

FIG. 5 is a vibrator 21 of the vibration actuator according to the present embodiment.
FIG. 6 is an explanatory diagram showing with time that the elliptical movement is generated on the drive surface by combining the longitudinal vibration and the torsional vibration that occur in FIG.

FIG. 6 is a cross-sectional view showing the entire configuration of the vibration actuator of this embodiment.

FIG. 7 is an exploded perspective view of a vibration actuator according to a second embodiment.

FIG. 8 is a perspective view showing a conventional example of a vertical-torsion vibration type vibration actuator.

FIG. 9 is an exploded perspective view showing a stator of a vibration actuator of a vertical-torsion vibration type.

FIG. 10 is a cross-sectional view showing the structure of a variant mode degenerate vibration actuator.

FIG. 11 is a perspective view showing a structure of a stator used for a variant mode degenerate vibration actuator.

[Explanation of symbols]

 20 Vibration actuator 21 Vibrator 21a Driving surface 21b, 21c Semi-cylindrical elastic body 22 Moving element 23a, 23b Piezoelectric element 24, 25, 26 Electrode 24a, 25a, 26a Electrode projecting part 24-1a, 25-1a, 26- 1a Electrode overhanging part 31 Oscillating part 32 Transfer part 33 T amplifying part 34 L amplifying part 35 Detecting part 36 Control part 41 Fixed shaft 42a, 42b Mounting bolt 43 Bearing 44 Pressing member 45 Adjusting member

Claims (3)

[Claims] 1. A plurality of electric motors excited by a drive signal
An elastic body that holds a mechanical energy conversion element and an electrode sandwiched between the electro-mechanical energy conversion element in a laminated state, and that generates a driving force on a driving surface that is an end surface of the element and the elastic body. A vibration actuator, comprising: a relative motion member that is in pressure contact with and is rotatably supported, wherein the electrode is an electrode overhanging portion for applying a voltage from the outside to an end face side facing the drive surface. A vibration actuator comprising: 2. The vibration actuator according to claim 1, wherein the electrode protrusions are arranged at positions that do not contact each other. 3. The vibration actuator according to claim 1, wherein longitudinal vibration and torsional vibration are generated in the elastic body to generate a driving force on the drive surface. Vibration actuator.