JPH0998590A - Oscillation actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the driving efficiency by providing an elastic body with a supporting member having stiffness in the amplitude direction of second oscillation mode higher than that of first oscillation mode. SOLUTION: The oscillation actuator comprises a planar elastic body 11 for urging piezoelectric elements 12a, 12b against one plane 11a, and a relative movement member coming into pressure contact with the other plane 11b of elastic body 11. Supporting members 15a, 15b having stiffness in the direction of pressurization higher than that in the direction of relative movement are provided on the side face of elastic body 11 and then the piezoelectric elements 12a, 12b are oscillated to generate relative movement between the elastic body 11 and relative movement member. This structure enhances the driving efficiency and long term efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relative motion member that pressurizes and contacts an elastic body by harmonically generating a plurality of vibration modes in an elastic body to which an electromechanical conversion element such as a piezoelectric element is bonded. Belongs to a vibration actuator that produces relative motion between and.

[0002]

2. Description of the Related Art An electromechanical transducer such as a piezoelectric element, an electrostrictive element or a magnetostrictive element is bonded to the surface of an elastic body by, for example, bonding, and a driving voltage is applied to the electromechanical transducer to apply a drive voltage to the elastic body. 2. Description of the Related Art There is known a vibration actuator that generates a plurality of vibration modes in harmony and generates an elliptical motion on the surface of an elastic body, thereby causing relative movement between the elastic body and a relative motion member that is brought into pressure contact with the elastic body.

Regarding this type of vibration actuator, for example, "piezoelectric linear motor for moving optical pickup" (Yoshiro Tomikawa et al .: Proc. Of the 5th Dynamic Symposium on Electromagnetic Force, pp. 393-398) , Its configuration and load characteristics are reported.

FIG. 10 is a schematic sectional view showing the structure and support structure of this vibration actuator. As shown in the figure, on one surface of the rectangular flat plate-shaped elastic body base portion 1a,
Four piezoelectric elements 2 are attached. Piezoelectric elements 2a, 2b
Is a driving piezoelectric element for converting electric energy into mechanical energy, while piezoelectric elements 2c and 2d are vibration monitoring piezoelectric elements for converting generated displacement into electric energy and outputting the same to the outside.

At the position on the other plane of the elastic base portion 1a, which is the antinode of the bending vibration generated in the elastic body,
The driving force extracting portions 1b and 1c are provided in a protruding shape and are in contact with the relative motion member 5 in a pressurized state.

Here, when a driving voltage is applied to the driving piezoelectric elements 2a and 2b from a driving voltage generator (not shown), longitudinal vibration and bending vibration are generated in the elastic base portion 1a. A biasing mechanism 3 using a spring 3a or the like is attached via a fixing surface 4 to the central portion in the longitudinal direction of the elastic body 1 which serves as a common node for longitudinal vibration and bending vibration when such vibration occurs. The elastic body 1 is urged to the relative movement member 5 via the driving force output portions 1b and 1c.

The natural frequencies of the first-order mode of longitudinal vibration and the fourth-order mode of flexural vibration generated in the elastic body 1 are very similar in value. Therefore, the tips of the driving force output portions 1b and 1c (on the side of the contact surface with the relative motion member 5) are displaced in an elliptical shape, and a relative motion is generated with the relative motion member 5.

As described above, in order to cause the relative motion between the elastic body 1 and the relative motion member 5, it is necessary to press the elastic body 1 against the relative motion member 5. Conventionally, in order to reduce the attenuation of a plurality of vibration modes generated in the elastic body 1 as much as possible, the piezoelectric elements 2a and 2b are not directly urged by the urging mechanism 3, but the piezoelectric elements 2a and 2b are not directly urged by the urging mechanism 3 and the elastic body 1. The cushioning material 6 made of, for example, felt is interposed between the cushioning material 6 and the cushioning material 6 and is urged.

[0009]

However, in the vibration actuator support structure shown in FIG. 10, it is difficult not to damp the vibration generated in the elastic body 1 even though the cushioning material 6 is interposed, and the drive efficiency of the vibration actuator is improved. Had become one of the causes of inhibiting.

Further, the weather resistance of the cushioning material 6 is insufficient, or it deteriorates due to deterioration over time, so that the setting conditions of the pressing force for urging change, and the reliability of the vibration actuator deteriorates over time. There was a problem of doing.

Further, when the elastic body 1 is supported by the supporting structure shown in FIG. 10, the elastic body 1 is bent by the pressing force F. FIG. 11 is an explanatory diagram showing a state of bending that occurs in the elastic body 1 during pressurization. Since the pressing force F acts on the central portion of the elastic body base portion 1a in the longitudinal direction, the elastic body base portion 1a is bent and deformed as shown by the solid line in FIG.

By the way, since the driving force generated by the vibration actuator is determined by the product of the pressing force and the dynamic friction coefficient,
When it is desired to increase the driving force, the pressing force F is increased.
However, when the pressing force F is increased, as shown in FIG. 11, the flexural deformation generated in the elastic body 1a increases, and the contact area between the driving force extracting portions 1b and 1c and the relative motion member 5 decreases.

As a result, the sliding relationship between the elastic body 1 and the relative motion member 5 becomes unstable, resulting in uneven speed. In addition, uneven wear may occur on the sliding surfaces of the elastic body 1 and the relative motion member 5, which may shorten the life of the vibration actuator.

As described above, the conventional vibration actuator has low driving efficiency and low reliability over time.
There were problems such as uneven speed and short life.

[0015]

According to a first aspect of the present invention, there is provided an elastic body to which an electromechanical conversion element is joined, and a relative movement member which is brought into pressure contact with the elastic body. Excitation of the mechanical conversion element causes the elastic body to vibrate in a direction parallel to the contact surface with the relative motion member in a first vibration mode and a second vibration in a direction intersecting the vibration direction of the first vibration mode. A vibration actuator for generating a relative motion between the elastic body and the relative motion member, wherein the elastic body has a rigidity in the amplitude direction of the second vibration mode in the first vibration mode. Is provided with a support member having a rigidity higher than the rigidity in the amplitude direction.

According to a second aspect of the present invention, there is provided a rectangular parallelepiped elastic body to which the electromechanical conversion element is joined, and a relative movement member which is brought into pressure contact with the elastic body, and a drive voltage is applied to the electromechanical conversion element. By exciting the elastic body, longitudinal vibration that vibrates in a direction parallel to the contact surface with the relative motion member and bending vibration that bends in a direction intersecting the vibration direction of the longitudinal vibration are generated in the elastic body. A vibration actuator for causing a relative motion between a relative motion member and a member substantially vertical to a contact surface between an elastic body and the relative motion member, wherein the rigidity in the amplitude direction of the bending vibration is It is characterized in that a supporting member having a rigidity higher than that in the amplitude direction is provided.

According to a third aspect of the present invention, there is provided a rectangular parallelepiped elastic body to which the electromechanical conversion element is joined, and a relative motion member that is brought into pressure contact with the elastic body, and a drive voltage is applied to the electromechanical conversion element. Is a vibration actuator that generates a longitudinal motion and a bending vibration in an elastic body by generating a vibration to generate a relative motion between the elastic body and the relative motion member. It is characterized in that a support member having rigidity in the amplitude direction of bending vibration higher than rigidity in the amplitude direction of longitudinal vibration is provided on a surface substantially perpendicular to the contact surface with.

According to a fourth aspect of the present invention, in the vibration actuator according to the third aspect, the support member is provided on the surface of the elastic body and near the position where the bending vibration occurs.

According to a fifth aspect of the invention, in the vibration actuator according to the third aspect, the supporting member vibrates in the same direction as the longitudinal vibration generated in the supporting member rather than the natural frequency of the longitudinal vibration generated in the elastic body. It is characterized by a high natural frequency of vibration.

The invention of claim 6 is from claim 3 to claim 5.
In the vibration actuator described in any one of 1 to 3, the support member has a rigidity in the amplitude direction of the bending vibration generated in the elastic body and a rigidity in the amplitude direction of the longitudinal vibration generated in the elastic body, both of which are the shape of the support member. And / or the material is adjusted.

The invention of claim 7 is from claim 3 to claim 5.
In the vibration actuator described in any one of (1) to (7) above, the natural frequency of vibration in which the support member vibrates in the same direction as the bending vibration generated in the elastic body is
Alternatively, it is adjusted according to the material.

The invention of claim 8 is from claim 3 to claim 7.
In the vibration actuator described in any one of the items 1 to 3, the support member has a cross-sectional shape of I-shape, elliptical shape, T-shape.
It has a shape, an inverted T shape, or a rectangle.

The invention of claim 9 is from claim 3 to claim 8.
In the vibration actuator described in any one of the above items, the support member is detachably attached to the elastic body.

According to the invention of any one of claims 1 to 9, the elastic body is supported near the node of the bending vibration generated in the elastic body, and the second vibration mode (bending vibration) is used for supporting the elastic body. Since a support member in which the rigidity in the vibration direction of is higher than the rigidity in the vibration direction of the first vibration (longitudinal vibration) is used,
Vibration damping due to the support of the elastic body is suppressed. for that reason,
The decrease in drive efficiency is improved.

Further, since it is not necessary to use a cushioning material for supporting the elastic body, the reliability with time is improved. Further, since the elastic body is not supported by the central portion in the longitudinal direction of the elastic body, the flexure caused in the elastic body is reduced, and uneven speed and uneven wear of the driving force take-out portion are eliminated.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the following description of each embodiment will be given by taking an ultrasonic actuator that uses an ultrasonic vibration region as an example of the vibration actuator.

FIG. 1 is a perspective view showing a first embodiment of the present invention, FIG. 2 is a sectional view of a supporting member used in the first embodiment, and FIG. 3 is used in the first embodiment of the present invention. It is a perspective view which extracts and shows an elastic body, and FIG. 4 is explanatory drawing which shows the longitudinal vibration and bending vibration which generate | occur | produce in an elastic body over time.

As shown in FIGS. 1 and 3, as the ultrasonic actuator used in the first embodiment, the elastic body 11 to which the electromechanical conversion element 12 is joined and the relative movement to be brought into pressure contact with the elastic body 11 are used. A first vibration mode in which the elastic body 11 vibrates in a direction parallel to the contact surface with the relative motion member by exciting the electromechanical conversion element 12 by applying a drive voltage (not shown). (Longitudinal vibration) and a second vibration mode (flexural vibration) that vibrates in a direction intersecting the vibration direction of the first vibration mode, and performs relative motion between the elastic body 11 and the relative motion member. An ultrasonic actuator 10 that produces a moving motion was used.

That is, the ultrasonic actuator 10 of the first embodiment has a rectangular flat plate-like elastic body 11 and an elastic body 11.
The four piezoelectric elements 12a, 12b, 12c, 12d adhered and joined to one flat surface 11a, and the driving force extracting portion 1 provided in the other flat surface 11b of the elastic body 11 in the width direction.
3a, 13b.

The elastic body 11 is formed by molding an elastic member such as metal or plastic into a rectangular flat plate shape. The piezoelectric element 12 is formed in a thin plate shape by PZT, for example.
The piezoelectric elements 12a and 12b are driving piezoelectric elements that convert electric energy into mechanical energy, and AC voltages that are electrically different in phase by (π / 2) are applied from a drive voltage generator (not shown).

On the other hand, the piezoelectric elements 12p and 12p 'are vibration monitoring piezoelectric elements for monitoring the vibration state generated in the elastic body 11, and are connected to the control circuit. The body of the elastic body 11 is generally connected to the GND potential,
In that case, the electrode (common electrode) 12g is configured by means of soldering a lead wire to the elastic body 11 or by adhering a metal foil with a lead wire to the elastic body 11 as shown in FIG. .

The driving force take-out portion 13a formed in the shape of a protrusion,
In the present embodiment, 13b is provided at a position serving as an antinode of bending vibration generated in the elastic body 11 from the viewpoint of driving efficiency.
Although the driving force output portions 13a and 13b are formed integrally with the elastic body 11 in this embodiment, they may be assembled as separate parts.

Furthermore, sliding members 14a and 14b for stabilizing the sliding state with the relative motion member are attached to the bottom surfaces (contact surfaces with the relative motion member) of the driving force output portions 13a and 13b.

Here, the operating principle of the ultrasonic actuator 10 of this embodiment will be described with reference to FIG. FIG. 4A shows the time change of the two-phase high-frequency voltages A and B input to the ultrasonic actuator 10 at time t _1.
It is shown by the ~ time t _9. The horizontal axis of FIG. 4A indicates the effective value of the high frequency voltage. FIG. 4B shows the ultrasonic actuator 1.
0 shows the deformation of the cross section of the ultrasonic actuator 1.
0 to bending temporal change in vibration generated indicating the (t ₁ ~t _9). FIG. 4C shows how the cross section of the ultrasonic actuator 10 is deformed, and shows the temporal change (t _{1 to} t ₉ ) of the longitudinal vibration generated in the ultrasonic actuator 10. FIG.
(D) is a driving force extraction unit 1 of the ultrasonic actuator 10.
3a, 13b elliptic movements over time (t ₁ ~
t ₉ ) is shown.

Next, the ultrasonic actuator 1 of this embodiment
The operation of 0 will be described for each time change (t _{1 to} t ₉ ). At time t ₁ , the high frequency voltage A generates a positive voltage and the high frequency voltage B also generates the same positive voltage as shown in FIG. 4 (A). As shown in FIG. 4 (B), the bending motions due to the high frequency voltages A and B cancel each other out,
The masses Y1 and Z1 have zero amplitude. Also, FIG.
As shown in (C), the longitudinal vibration due to the high frequency voltages A and B is generated in the extending direction. The mass points Y2 and Z2 show the maximum elongation around the node X, as indicated by the arrows. As a result, as shown in FIG. 4 (D), both of the above-mentioned vibrations are combined, and the movement of the mass points Y1 and Y2 is synthesized by the mass point Y.
And the combination of the motions of the mass points Z1 and Z2 becomes the motion of the mass point Z.

At time t ₂ , the high frequency voltage B becomes zero and the high frequency voltage A generates a positive voltage as shown in FIG. 4 (A). As shown in FIG. 4 (B), a bending motion is generated by the high frequency voltage A, the mass point Y1 oscillates in the positive direction, and the mass point Z1 oscillates in the negative direction. Further, as shown in FIG. 4 (C), longitudinal vibration is generated by the high frequency voltage A, and the material point Y2 and the material point Z2 contracts than at time t _1. As a result, as shown in FIG. 4D, the above-mentioned both vibrations are combined, and the mass point Y
And the mass Z move counterclockwise as compared with the time t ₁ .

At time t ₃ , 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. 4 (A). As shown in FIG. 4 (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 t ₂ and shows the maximum negative amplitude value. Mass point Z1 is time t ₂
It is amplified in the positive direction more than when, and shows the maximum positive amplitude value. Further, as shown in FIG. 4C, the longitudinal vibrations due to the high frequency voltages A and B cancel each other out, and the mass points Y2 and Z2 return to their original positions. As a result, FIG. 4 (D)
As shown in, the above-mentioned both vibrations are combined and the mass point Y and the mass point Z are combined.
And move counterclockwise than at time t ₂ .

At time t ₄ , the high frequency voltage A becomes zero and the high frequency voltage B generates a negative voltage as shown in FIG. 4 (A). As shown in FIG. 4 (B), a bending motion is generated by the high frequency voltage B, the amplitude of the mass Y1 is lower than that at the time t ₃ , and the amplitude of the mass Z1 is less than that at the time t ₃ . Further, as shown in FIG. 4 (C), longitudinal vibration is generated by the high frequency voltage B, and the mass points Y2 and Z2 contract. As a result, as shown in FIG. 4 (D), both vibrations are combined, and the mass points Y and Z move counterclockwise as compared with the time point t ₃ .

At time t ₅ , as shown in FIG. 4 (A), the high frequency voltage A produces a negative voltage, and the high frequency voltage B produces the same negative voltage. As shown in FIG. 4B, the bending movements due to the high frequency voltages A and B cancel each other out, and the masses of the mass points Y1 and Z1 become zero. Also,
As shown in FIG. 4C, the longitudinal vibrations due to the high frequency voltages A and B are generated in the contracting direction. The mass points Y2 and Z2 show the maximum contraction around the node X, as indicated by the arrows. As a result, as shown in FIG. 4 (D), both of the above vibrations are combined, and the mass points Y and Z move counterclockwise as compared with the time point t ₄ .

As the time t _{6 to} t ₉ changes,
Bending vibration and longitudinal vibration are generated similarly to the above-described principle, and as a result, as shown in FIG. 4D, the mass points Y and Z move counterclockwise to make an elliptic motion.

On the basis of the above principle, this ultrasonic actuator is constructed so that an elliptic motion is generated at the tips of the driving force output portions 13a and 13b to generate a driving force.
Therefore, since the tips of the driving force output portions 13a and 13b are pressed against the relative motion member (not shown), relative motion is generated between the elastic body 11 and the relative motion member.

As described above, by applying alternating voltages that are electrically different in phase by (π / 2) to the piezoelectric elements 12a and 12b, longitudinal vibration and bending vibration are generated in the elastic body 11,
Each becomes a motion component in the driving direction and a motion component perpendicular to the driving direction to generate an elliptic motion.

Further, in the ultrasonic actuator 10 according to the present embodiment, as shown in FIGS. 1 and 2, the two side surfaces of the elastic body 11 are located at or near the node position of the bending vibration generated in the elastic body 11. And ultrasonic actuator 10
The supporting member 15 having a cross-sectional shape in which the rigidity of the longitudinal vibration in the amplitude direction is made lower than the rigidity of the bending vibration in the amplitude direction at a position where the amplitude of the longitudinal vibration that is the source of the propulsive force generated in
a, 15b (15c, 15d) are provided, and this support member 1
5a and 15b (15c and 15d) are pressed by a biasing mechanism (not shown). The support members 15c and 15d are not shown in FIG.
It is arranged on the side surface facing the installation surface of 5b.

In other words, the plate-shaped elastic body 11 in which the piezoelectric elements 12a and 12b are joined to the one flat surface 11a, and the relative movement member (not shown) which is pressed into contact with the other flat surface 11b of the elastic body 11 ) And by applying a drive voltage to excite the piezoelectric elements 12a and 12b.
In addition, the elastic body 11 is a synthetic vibration of longitudinal vibration and bending vibration.
In the ultrasonic actuator 10 that generates relative motion between the relative motion member and the relative motion member, the support member 15 on the side surface of the elastic body 11 has a rigidity in the pressing direction higher than that in the relative motion direction.
a and 15b are provided.

Such support members 15a, 15b (15
c, 15d) are preferably made of the same material as the elastic body 11, are processed into a cross-sectional shape shown in FIG. 1 or 2 by appropriate means, and are installed on the side surface of the elastic body 11. The support members 15a, 15b (15c, 15d) and the elastic body 11 may be integrated or separated, but it is advantageous from the viewpoint of suppressing an increase in manufacturing cost.

As described above, the central portion of the elastic body 11 in the longitudinal direction is not supported by the urging mechanism, but the supporting members 15a and 15b (15c and 15d) having the above-described cross-sectional shape are arranged at the node position of the bending vibration or the node position thereof. The elastic body 11 is installed in the vicinity.
It is possible to reduce the suppression of flexural vibration generated in the.

Further, since it is not necessary to consider the bending of the elastic body 11, it is possible to increase the applied pressure to improve the driving force and improve the driving efficiency. Also, the elastic body 1
Since the support members 15a, 15b (15c, 15d) provided on the side surface of the elastic body 11 are pressed instead of directly pressing 1, it is not necessary to consider the suppression of the vibration generated in the elastic body 11, and the cushioning material is used. Since it is not necessary to use it, the weather resistance and reliability of the ultrasonic actuator are improved.

Further, since the bending of the elastic body 11 during the pressurization can be suppressed as small as possible,
Since the contact state between the driving force output portions 13a and 13b of the elastic body 11 and the relative motion member can be stably maintained regardless of the magnitude of the pressing force, uneven speed and uneven wear generated in the driving force output portions 13a and 13b can be prevented. It can be suppressed and the life of the ultrasonic actuator can be extended.

Particularly, the support members 15a, 15b (15c,
15d), the natural frequency in the amplitude direction of the first vibration mode (longitudinal vibration in this embodiment) that vibrates in the direction parallel to the contact surface with the relative motion member generated in the elastic body is the first frequency of the elastic body.
Compared with the natural frequency of the vibration mode, for example, 1.2 times or more can prevent significant vibration damping of the elastic body 11. Further, it is possible to improve the responsiveness to vibration and improve the driving performance.

(Second Embodiment) FIG. 5 is a perspective view showing the structure of the ultrasonic actuator of the second embodiment, and FIG. 6 is used for the ultrasonic actuator used in the ultrasonic actuator of the second embodiment. It is sectional drawing which shows the cross-sectional shape of a support member.

In the following description of each embodiment, only the parts different from the first embodiment described above will be described, and the description of the overlapping parts will be appropriately omitted. In this embodiment, the cross-sectional shape of the support members 16a and 16b (16c and 16d) is changed from I-shaped to elliptical. Even if it is oval,
The supporting members 16a, 16b (16c, 16d) have a rigidity in the amplitude direction of the longitudinal vibration lower than that in the amplitude direction of the flexural vibration, and the same effect as that of the first embodiment can be obtained.

Further, the supporting members 16a, 16 of this embodiment
b (16c, 16d) is the support member 15 of the first embodiment.
It has a simpler structure than the a and 15b (15c and 15d), and is easy to manufacture.

(Third Embodiment) FIG. 7 is a perspective view showing the structure of the third embodiment. In the present embodiment, two semi-cylindrical elastic bodies 21a and 21b made of metal, four piezoelectric elements 22 for vertical vibration, two sheets sandwiched by these, and a total of four twisting elements, two sheets each. Piezoelectric element 23 for vibration
And a cylindrical relative movement member (not shown) that is brought into pressure contact with the drive surface 24 that is an end surface.

A thin plate-like electrode for applying a driving voltage is laminated between each piezoelectric element together with each piezoelectric element. A drive voltage having a phase difference of (π / 2) is applied to each of the piezoelectric elements 22 and 23 from a drive voltage generator (not shown). When a drive voltage is applied to the four piezoelectric elements 22, the elastic body 21 is stretched to the maximum in the + direction during one cycle (T =
0) → contraction (T = π / 4) → amplitude 0 (T = 2π / 4) →
Contraction in the − direction (T = 3π / 4) → Maximum contraction in the − direction (T
= 4π / 4) → extension (5π / 4) → amplitude 0 (T = 6π /
4) Displaces in the + direction (T = 7π / 4).

On the other hand, when a drive voltage is applied to the four piezoelectric elements 23 that give a displacement that twists the drive surface in two directions, the elastic body 21 has a torsional displacement of 0 (T = 0) → torsional displacement to the right (T = π / 4) → maximum torsional displacement to the right (T = 2π / 4) → contraction (T = 3π / 4) → torsional displacement 0 ( T = 4π / 4) → torsional displacement to the left (5π /
4) → The maximum twist displacement (T = 6π / 4) → contraction (T = 7π / 4) is displaced leftward.

Therefore, the elastic body 21 intermittently contacts the relative motion member due to the vibration component of the longitudinal vibration, and
When the relative motion member is contacted by the vibration component of the longitudinal vibration, the relative motion member is driven rightward.

In the ultrasonic actuator configured as described above, in this embodiment, the supporting members 25a and 25b having the same cross-sectional shape as those of the first embodiment are provided at the portions located at the nodes of longitudinal vibration. The support members 25a and 25b are made of metal, and are joined to the semi-cylindrical elastic bodies 21a and 21b by welding.

A biasing mechanism is appropriately engaged with the support members 25a and 25b to press the elastic body 21 against the relative movement member (not shown) on the drive surface 24 so that the elastic body 21 comes into contact with the relative movement member. Also in the present embodiment, the support members 25a and 25b have the rigidity in the amplitude direction of the torsional vibration lower than the rigidity in the amplitude direction of the longitudinal vibration, which is exactly the same as in the first and second embodiments. The effect can be obtained.

(Fourth Embodiment) FIG. 8 is a perspective view showing the structure of the fourth embodiment. Since the present embodiment is a partial modification of the third embodiment, in the following description, only parts having different structures will be described, and description of common parts will be omitted.

In this embodiment, hollow semi-cylindrical elastic bodies 21-1a and 21-1b are used, and compared with the solid semi-cylindrical elastic bodies 21a and 21b used in the third embodiment. Then, the amplitude of the torsional vibration generated on the driving surface 24 is expanded, and a larger driving force can be obtained.

(Fifth Embodiment) FIG. 9 is a perspective view showing a partially broken structure of the fifth embodiment. Since the present embodiment is a partial modification of the fourth embodiment, only the portions having different structures will be described in the following description, and description of common portions will be omitted.

In this embodiment, unlike the fourth embodiment, the two support members 25a and 25b are not joined to the outer surfaces of the hollow semi-cylindrical elastic bodies 21-1a and 21-1b, respectively. , One support member 26 to the elastic body 2
The urging mechanism (not shown) is appropriately disposed inside the elastic body 21, and the urging mechanism allows the elastic body 21 to be moved to the relative motion member (not shown) via the drive surface 24.
Under pressure. Since the support member 26 does not project to the outer surface of the elastic body 21, the size of the entire ultrasonic actuator can be reduced.

(Modification) In each of the embodiments described above, the piezoelectric element is used as the electromechanical conversion element, but the present invention is not limited to this, and an electrostrictive element, a magnetostrictive element, or the like is used. It is also possible.

Further, it is possible to use a supporting member having a cross-sectional shape different from that of the supporting member used in the first to fifth embodiments. For example, the cross-sectional shape is T-shaped, inverted T
Examples include mold, rectangular, groove-shaped, and H-shaped support members.
All of them have the first rigidity in the amplitude direction of the second vibration.
The rigidity is lower than the rigidity in the vibration amplitude direction, and the same effect as that of each of the above-described embodiments can be obtained.

Further, in each of the embodiments, the case where the shape is devised so as to make the rigidity of the second vibration in the amplitude direction higher than the rigidity of the first vibration in the amplitude direction is taken as an example, but it is limited to only this mode. However, anisotropy of rigidity is obtained by forming the supporting member using a composite material such as FRP, or the constituent material of the amplitude direction component of the second vibration and the amplitude direction component of the first vibration are obtained. The constituent material may be different.

[0066]

According to the first aspect of the invention, the elastic body to which the electromechanical conversion element is joined has the first vibration mode in the direction including the contact surface with the relative motion member and the first vibration mode in the direction intersecting the contact surface. When a combined vibration of two vibration modes is generated and a relative motion is generated between the elastic body and the relative motion member,
Since the elastic member is provided with a support member whose rigidity in the amplitude direction of the second vibration is higher than that in the amplitude direction of the first vibration, it is possible to improve the driving efficiency, increase the reliability over time, or It is possible to extend the life.

According to the second aspect of the invention, the plate-like elastic body having the electromechanical conversion element bonded to one of the planes intersects the longitudinal vibration and the contact surface which expand and contract in the direction including the contact surface with the relative motion member. When a motion that causes a relative motion between the elastic body and the relative motion member, which is a combined vibration of the bending vibration that bends in a direction, is generated, the rigidity in the amplitude direction of the bending vibration is increased vertically on the side surface of the elastic body. Since the support member having the rigidity higher than the rigidity in the amplitude direction of the motion is provided, it is possible to improve the driving efficiency, increase the reliability over time, or extend the life.

According to the third aspect of the present invention, the plate-like elastic body having the electromechanical conversion element bonded to one of the planes is provided with a composite vibration of the longitudinal vibration and the bending vibration between the elastic body and the relative motion member. When a motion that causes a relative motion is generated, a supporting member is provided on the side surface of the elastic body so that the rigidity in the pressing direction is higher than the rigidity in the relative motion direction, so that the driving efficiency can be improved and the reliability over time is improved. It is possible to increase the durability or extend the life.

According to the invention of claim 4, in the ultrasonic actuator according to claim 3, since the support member is provided at a position on the surface of the elastic body and serving as a node of bending vibration, a necessary power transmission function is provided. Can be efficiently maintained.

According to a fifth aspect of the invention, in the ultrasonic actuator according to the third aspect, since the resonance frequency of the bending vibration of the support member is higher than the resonance frequency of the longitudinal vibration in the amplitude direction, the vibration vibration against the vibration is prevented. Responsiveness can be improved,
It is possible to improve driving performance.

According to the sixth or seventh aspect of the invention, in the ultrasonic actuator according to any one of the third to fifth aspects, the amplitude direction of the bending vibration of the support member and the longitudinal motion Since both the rigidity in the amplitude direction and the resonance frequency are adjusted by the shape and / or material of the supporting member, it is easy and reliable, and the responsivity to vibration can be achieved without forming the supporting member into a complicated sectional shape. Therefore, the driving performance can be improved.

According to an eighth aspect of the invention, in the ultrasonic actuator according to any one of the third to seventh aspects, the cross-sectional shape of the support member is I-shaped, elliptical-shaped,
Since it is T-shaped, inverted T-shaped or rectangular, it is possible to set the cross-sectional shape of the supporting member having an optimum shape in consideration of the installation position, manufacturing cost and the like.

According to a ninth aspect of the invention, in the ultrasonic actuator according to any one of the third to eighth aspects, the supporting member is provided so as to be detachable from the elastic body. The increase in cost can be suppressed.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is a sectional view of a support member used in the first embodiment.

FIG. 3 is an extracted perspective view showing an elastic body used in the first embodiment of the present invention.

FIG. 4 is an explanatory diagram showing longitudinal vibration and bending vibration generated in an elastic body over time.

FIG. 5 is a perspective view illustrating a configuration of an ultrasonic actuator according to a second embodiment.

FIG. 6 is a cross-sectional view showing a cross-sectional shape of a support member used in the ultrasonic actuator according to the second embodiment.

FIG. 7 is a perspective view showing a configuration of a third embodiment.

FIG. 8 is a perspective view showing a structure of a fourth embodiment.

FIG. 9 is a perspective view showing a partially broken structure of the fifth embodiment.

FIG. 10 is a schematic cross-sectional view showing a structure and a support structure of a conventional ultrasonic actuator.

FIG. 11 is an explanatory diagram showing a bending state that occurs in the elastic body during pressurization.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Ultrasonic actuator 11 Elastic body 11a, 11b Flat surface 12a, 12b Driving piezoelectric element 12p, 12p 'Vibration monitoring piezoelectric element 13a, 13b Driving force extraction part 14a, 14b Sliding member 15a, 15b, 15c, 15d Supporting member 16a , 16b, 16c, 16d Support member 21a, 21b, 21-1a, 21-1b Elastic body 22,23 Piezoelectric element 24 Driving surface 25a, 25b, 26 Support member

Claims (9)

[Claims] 1. An elastic body to which an electromechanical conversion element is joined, and a relative motion member that is brought into pressure contact with the elastic body are provided, and a drive voltage is applied to excite the electromechanical conversion element. A first vibration mode that vibrates in the elastic body in a direction parallel to a contact surface with the relative motion member, and a second vibration mode that vibrates in a direction intersecting a vibration direction of the first vibration mode.
A vibration actuator that generates a vibration mode to generate a relative motion between the elastic body and the relative motion member, wherein the elastic body has rigidity in the amplitude direction of the second vibration mode. Is provided with a supporting member having a rigidity higher than the rigidity of the first vibration mode in the amplitude direction. 2. A rectangular parallelepiped elastic body to which an electromechanical conversion element is joined, and a relative movement member that is brought into pressure contact with the elastic body, and a drive voltage is applied to excite the electromechanical conversion element. As a result, the elastic body is caused to generate a longitudinal vibration vibrating in a direction parallel to the contact surface with the relative motion member and a bending vibration bending in a direction intersecting the vibration direction of the longitudinal vibration, and the elastic body is generated. A vibration actuator that causes a motion to perform a relative motion between the relative motion member and the relative motion member, in a plane substantially perpendicular to a contact surface between the elastic body and the relative motion member, in the amplitude direction of the bending vibration. A vibration actuator comprising a support member having a rigidity higher than the rigidity in the amplitude direction of the vertical vibration. 3. A rectangular parallelepiped elastic body to which an electromechanical conversion element is joined, and a relative motion member that is brought into pressure contact with the elastic body, and a drive voltage is applied to excite the electromechanical conversion element. A vibration actuator that generates longitudinal vibration and bending vibration in the elastic body to thereby generate a relative motion between the elastic body and the relative motion member. A vibration actuator, comprising: a support member having a rigidity in the amplitude direction of the bending vibration higher than a rigidity in the amplitude direction of the longitudinal vibration, provided on a surface substantially perpendicular to a contact surface with the moving member. 4. The vibration actuator according to claim 3, wherein the support member is provided on a surface of the elastic body and near a position serving as a node of the bending vibration. 5. The vibration actuator according to claim 3, wherein the support member vibrates in the same direction as the vertical vibration generated in the support member, rather than the natural frequency of the vertical vibration generated in the elastic body. A vibration actuator characterized by having a high natural frequency. 6. One of claims 3 to 5
In the vibration actuator described in the paragraph 1, the support member has a rigidity in the amplitude direction of the bending vibration generated in the elastic body and a rigidity in the amplitude direction of the longitudinal vibration generated in the elastic body, both of which are the shape of the support member. And / or the material is adjusted by the vibration actuator. 7. The method according to any one of claims 3 to 5.
In the vibration actuator described in the paragraph 1, the support member is characterized in that a natural frequency of vibration vibrating in the same direction as the bending vibration generated in the elastic body is adjusted by a shape and / or a material of the support member. Vibration actuator. 8. Any one of claims 3 to 7
In the vibration actuator described in the paragraph 1, the cross-sectional shape of the support member is I-shaped, elliptical, T-shaped, inverted T-shaped, or rectangular. 9. Any one of claims 3 to 8
In the vibration actuator described in the paragraph (1), the support member is detachably attached to the elastic body.