JPH0739178A - Ultrasonic actuator - Google Patents

Abstract

(57) [Abstract] [Purpose] To minimize the influence of the holding of the vibrating body by the vibrating body holding portion on the flexural vibration of the vibrating body, and to obtain a stable and large driving force. [Structure] A rod-shaped vibrating body 11, a vibrating body holding portion 12a,
12b, conical protrusions 13a to 13d, and a holding screw 14
The conical protrusions 13a to 13d, which have a and 14b and are integrated with the vibrating body holding portions 12a and 12b, are symmetrically point-contacted at four widthwise central portions of the four side surfaces of the vibrating body 11, and the vibrating body holding portion 12 is formed.
By tightening the screws a and 12b with the holding screws 14a and 14b, the vibrating body 11 is evenly and stably held by point contact, and the influence of the amplitude attenuation on the flexural vibration of the vibrating body 11 due to the holding is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic actuator for driving a moving body disposed under pressure contact with a vibrating body by exciting elastic vibration in the vibrating body composed of a piezoelectric body and an elastic body. Is.

[0002]

2. Description of the Related Art The prior art of an ultrasonic actuator will be described below with reference to the drawings.

FIG. 7 shows a vibrator used in a conventional ultrasonic actuator. Exciting flexural vibration in the rod-shaped vibrating body 80 causes rotational movement on the surface of the vibrating body 80. In the figure, 81 is an elastic body such as metal or ceramic, and 82a and 82b are piezoelectric bodies such as piezoelectric ceramics. The piezoelectric bodies 82a and 82b are polarized in the thickness direction after the electrodes are formed on their respective principal surfaces, and when an electric field is applied between the electrodes, the piezoelectric bodies 82a and 82b are deformed in the length direction.

As shown in FIG. 7A, the piezoelectric bodies 82a,
82b are elastic members 81 in a state where they are arranged at right angles to each other.
Are bonded to the two surfaces, and thus the vibrating body 80 is configured. When an electric field is applied to one of the piezoelectric bodies 82a in a direction perpendicular to the elastic body surface, that is, in the same direction as polarization, the piezoelectric body 8a
2a is deformed, the elastic body 81 is deformed accordingly, and the entire vibrating body 80 is bent as shown in FIG. 7B. In FIG. 7B, the piezoelectric body 82a is flexed in a contracting direction, but by reversing the direction of the electric field applied to the piezoelectric body 82a, the vibrating body 80 is flexed in the extending direction of the piezoelectric body 82a. be able to. The same phenomenon can occur in the other piezoelectric body 82b.

FIG. 7C is a front view of the vibrating body 80 as seen from the longitudinal direction. When an alternating electric field having a phase difference of 90 degrees is applied to each of the piezoelectric bodies 82a and 82b, the vibrating body 8 is generated.
Each surface of 0 causes a rotary motion of a magnitude according to the vibration amplitude of the vibrating body 80. At this time, the vibration V _{Y in the} Y direction due to the piezoelectric body 82a and the vibration V _{X in the} X direction due to the piezoelectric body 82b are combined into a rotary motion R. This rotational movement is caused by the piezoelectric body 8
The rotation direction can be changed according to the phase difference of the AC electric fields applied to 2a and 82b. By setting the frequency of the AC electric field in the vicinity of the resonance frequency of the vibrating body 80, the amplitude of the flexural vibration can be increased and the vibration can be efficiently generated. This rotary motion is used to drive as an ultrasonic actuator.

FIG. 8 is a perspective view showing a conventional example of an ultrasonic actuator using a vibrating body similar to that shown in FIG. In the figure, 90 is a rod-shaped vibrating body, 91 is an elastic body, 92a and 92b are piezoelectric bodies (92b is not shown), 93a and 93b are vibrating body holding portions, 94 is a moving body,
Reference numeral 95 is a moving body supporting portion, and 96 is an electric field applying wiring (lead wire). The vibrating body 90 is configured by bonding piezoelectric bodies 92a and 92b for vibration excitation to the side surface and the lower surface of an elastic body 91. The moving body 94 is arranged with its base portion supported by the moving body supporting portion 95, and by applying a pressing force indicated by a thick downward arrow to the moving body supporting portion 95, the moving body 94 is moved to the vibrating body 90. Pressure contact is made with the upper surface. The moving body 94 is supported by the moving body supporting portion 95 so as to be movable only in the arrow direction orthogonal to the longitudinal direction of the vibrating body 90.

The vibrating body 90 includes vibrating body holding portions 93a and 93b.
Is held fixed by. The electric field applying wiring 96 is attached to the elastic body 91 and the piezoelectric bodies 92a and 92b in the vibrating body 90, and by applying an electric field to the piezoelectric bodies 92a and 92b forming the vibrating body 90, the vibrating body 9
A flexural vibration is generated at 0 to generate a rotational movement in the vibrating body 90, and this rotational movement allows the moving body 94 to reciprocate in the moving direction indicated by the arrow in the figure.

[0008]

However, in the ultrasonic actuator utilizing the flexural vibration of the rod-shaped vibrating body having the conventional structure, the vibrating body 90 is attached to the vibrating body holding portions 93a, 93.
It was held by direct and hard surface contact with b. Therefore, the holding of the surface contact greatly affects the flexural vibration of the vibrating body 90, the amplitude of the flexural vibration is attenuated, and the vibration mode may be changed. As a result, there has been a problem that the driving force is remarkably reduced due to a reduction in the size of the rotary motion or a change in the state of the rotary motion.

The present invention solves the above-mentioned problems of the prior art, and minimizes the influence of the holding of the vibrating body by the vibrating body holding portion on the flexural vibration of the vibrating body to obtain a stable and large driving force. It is an object of the present invention to provide an ultrasonic actuator that can be used.

[0010]

The ultrasonic actuator according to the present invention is premised on that a vibrating body composed of a piezoelectric body and an elastic body is excited by elastic vibration so as to be brought into pressure contact with the vibrating body. Driving a moving body,
A rod-shaped vibrating body is adopted as the vibrating body, and a flexural vibration is adopted as the elastic vibration.

The ultrasonic actuator according to claim 1 is characterized in that the vibrating body is held in point contact with the vibrating body holding portion.

The ultrasonic actuator according to claim 2 is
The vibrating body is held in line contact with the vibrating body holding portion.

An ultrasonic actuator according to claim 3 is
The vibrating body is held with a cushioning material interposed between the vibrating body and the vibrating body holding portion.

The ultrasonic actuator according to claim 4 is
The vibrating body is subjected to hole processing or groove processing, and the vibrating body is held in the vibrating body holding portion via the hole processing portion or groove processing portion.

The ultrasonic actuator according to claim 5 is
In any one of claims 1 to 4,
The vibrating body is held in the vibrating body holding portion in the vicinity of the flexural vibration node of the vibrating body.

[0016]

In the ultrasonic actuator of claim 1, the vibrating body is held in point contact, and in the ultrasonic actuator of claim 2, the vibrating body is held in line contact. Therefore, the contact area between the vibrating body and the vibrating body holding portion is reduced. Can be reduced. As a result, the inhibiting factors for the flexural vibration are reduced, and a larger vibration amplitude is obtained.

In the ultrasonic actuator of the third aspect, since the cushioning material is interposed between the vibrating body and the vibrating body holding portion, attenuation of the vibration amplitude can be suppressed even in the case of surface contact.

In the ultrasonic actuator of the fourth aspect, since the vibrating body is held through the hole processing portion or the groove processing portion formed on the vibrating body, the positional accuracy of holding is improved.

In the ultrasonic actuator of the fifth aspect, since the vibrating body is held in the vicinity of the flexural vibration node, the effect of holding the vibrating body by the vibrating body holding portion on the flexural vibration of the vibrating body is sufficiently suppressed, and a large driving force is achieved. Power is gained.

[0020]

Embodiments of the present invention will now be described in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a front view showing a state in which a regular quadrangular prism-shaped vibrator in an ultrasonic actuator is held by point contact. This figure is a view of the rod-shaped vibrating body held in the longitudinal direction of the vibrating body. In FIG. 1, 11 is a vibrating body, 12a and 12b are vibrating body holding portions,
13a to 13d are conical protrusions, and 14a and 14b are vibrators 1.
It is a holding screw for adjusting the holding pressure with respect to 1.
The vibrating body 11 is in the shape of a regular square pole. This vibrator 1
1 is an elastic body (not shown) made of metal or ceramic
A piezoelectric body (not shown) polarized in the thickness direction is adhered to the two surfaces orthogonal to each other. A screw insertion hole (not shown) for inserting the holding screws 14a, 14b is formed in the upper vibrating body holding portion 12a, and a screw for screwing the holding screws 14a, 14b in the lower vibrating body holding portion 12b. A hole (not shown) is formed. Such a pair of upper and lower vibrating body holding portions 12a and 12b is a bar-shaped vibrating body 11
Two sets are provided at two locations in the longitudinal direction of the.

The vibrating body holding portions 12a and 12b have a concave shape, and conical protrusions 13a to 13d are provided on both sides of the concave portion.
Are fixed, and the sharp tips of the conical protrusions 13a to 13d are in point contact with the widthwise central portions of the four side surfaces of the vibrating body 11 to hold the vibrating body 11 uniformly and stably. That is, since the four symmetrical positions of the vibrating body 11 are held by point contact, the influences on the two flexural vibrations excited in the vibrating body 11 which are orthogonal to each other can be made substantially equal and small. . The point contact holding at four points is performed at two locations in the longitudinal direction of the vibrating body 11, and the two locations are set near the flexural vibration nodes (described later).
Therefore, the influence of the amplitude attenuation that the holding has on the flexural vibration of the vibrating body 11 is further reduced, and the vibrating body 11
Can perform an ideal rotary motion.

(Embodiment 2) In the embodiment of FIG. 1, the side surface of the vibrating body 11 is held by point contact, whereas in the embodiment of FIG. 2, the vibrating body is held at the corners (ridge lines). To do. In FIG. 2, 21 is a vibrating body, and 22a, 2
Reference numeral 2b is a vibrating body holding portion, 23a to 23d are tapered protrusions, and 24a and 24b are holding screws for adjusting the holding pressure with respect to the vibrating body 21. Upper and lower vibrating body holders 22
Two sets of a and 22b are provided at two locations in the longitudinal direction of the rod-shaped vibrating body 21.

The vibrating body holding portions 22a and 22b have a concave shape, and taper-shaped projections 23a to 23a are provided on both sides of the concave portion.
23d is fixed, and the ridge lines of the tapered protrusions 23a to 23d are in point contact with the four ridge lines of the vibrating body 21 to hold the vibrating body 21 evenly and stably. Also in the case of this embodiment, since four symmetrical positions of the vibrating body 21 are held in point contact, the influences on the two flexural vibrations that are excited in the vibrating body 21 and are orthogonal to each other are substantially equal to each other. Can be made smaller. The point contact holding at four points is carried out at two points in the longitudinal direction of the vibrating body 21, and
Since the location is set in the vicinity of the node of the flexural vibration, the influence of the amplitude attenuation that the holding has on the flexural vibration of the vibrating body 21 can be further reduced, and the vibrating body 21 can perform an ideal rotational movement.

(Embodiment 3) In this embodiment, the vibrating body is held by line contact. FIG. 3A is a front view of the ultrasonic actuator seen from the longitudinal direction of the vibrating body, and FIG. 3B is an enlarged cross-sectional view taken along the line AA of FIG. 3A.
In FIG. 3, 31 is a vibrating body, 32a and 32b are vibrating body holding portions, 33a and 33b are tapered projections, 34a and 3b.
Reference numeral 4b is a holding screw for adjusting the holding pressure. The tapered projections 33a and 33b are respectively the vibrating body holding portions 32a and 3b.
It is formed in the center of the inner surface of 2b. The vibrating body 31 is in the shape of a regular quadrangular prism, and two parallel surfaces are tapered protrusions 33.
It is pinched and fixed by the ridge lines of a and 33b. The contact between the vibrating body 31 and the tapered protrusions 33a and 33b is line contact in the direction orthogonal to the longitudinal direction of the vibrating body 31. In addition, the holding screw 34a, the holding screw 34a,
34b is formed with a screw insertion hole (not shown), and the lower vibrating body holding portion 32b has a holding screw 34a,
A screw hole (not shown) into which 34b is screwed is formed. Two sets of such upper and lower vibrating body holding portions 32a and 32b are provided at two locations in the longitudinal direction of the rod-shaped vibrating body 31.

The holding pressure for the vibrating body 31 is the holding screw 3
4a, 34b.

(Embodiment 4) In this embodiment, a vibrating body is held via a cushioning material. FIG. 4 is a front view of the ultrasonic actuator viewed from the longitudinal direction of the vibrating body. In FIG. 4, 41 is a vibrating body, 42a and 42b are vibrating body holding portions, 43a and 43b are cushioning materials, and 44a and 44b are holding screws for adjusting holding pressure. The cushioning materials 43a and 43b are fitted in the recesses of the vibrating body holding portions 42a and 42b, respectively. The vibrating body 41 is in the shape of a regular square pole, and its two parallel surfaces are held in surface contact with each other by the cushioning materials 43a and 43b. A screw insertion hole (not shown) for inserting the holding screws 44a and 44b is formed in the upper vibrating body holding portion 42a, and holding screws 44a and 44b are screwed into the lower vibrating body holding portion 42b. Screw holes (not shown) are formed. Such upper and lower vibrating body holding portions 42a,
Two sets of 42b are provided at two positions in the longitudinal direction of the rod-shaped vibrating body 41. The holding pressure on the vibrating body 41 is adjusted by the holding screws 44a and 44b. The cushioning material 43 is provided between the vibrating body 41 and the vibrating body holding portions 42a and 42b.
Since a and 43b are interposed, it is possible to reduce vibration inhibition rather than directly pressing the vibrating body with a hard member, and to suppress damping of the vibration amplitude.

(Embodiment 5) In this embodiment, a vibrating body is held near the neutral axis of its flexural vibration. FIG. 5 is a front view of the ultrasonic actuator viewed from the longitudinal direction of the vibrating body. In FIG. 5, 51 is a vibrating body, 5
Reference numerals 2a and 52b are vibrating body holding portions, 53a and 53b are holding pins, and 54a and 54b are holding screws for adjusting holding pressure. The vibrating body 51 is in the shape of a regular square pole, and its parallel 2
Hole processing portions or groove processing portions corresponding to the shapes of the holding pins 53a and 53b are formed in the holding portions of the surface by machining. The hole processing portion or groove processing portion is formed up to the vicinity of the neutral axis (neutral surface) of the flexural vibration of the vibrating body 51, that is, the surface that does not expand or contract. Holding pins 53a, 53
In b, the respective base portions are planted in the vibrating body holding portions 52a and 52b, and the sharp tips are pressed against the hole processing portion or groove processing portion of the vibrating body 51. The upper vibrating body holding portion 52a
Is formed with a screw insertion hole (not shown) through which the holding screws 54a and 54b are inserted, and a screw hole (not shown) into which the holding screws 54a and 54b are screwed is formed in the lower vibrating body holding portion 52b. Has been formed. A pair of such upper and lower vibrating body holding portions 52a and 52b is arranged in the longitudinal direction of the rod-shaped vibrating body 51.
Two sets are provided at the location.

The holding pressure for the vibrating body 51 is the holding screw 5.
4a, 54b. Since the holding pins 53a and 53b are inserted and pressed into the machined hole-processed portion or groove-processed portion, positioning can be performed easily and accurately. Further, the surface of the vibrating body 51 repeats expansion and contraction during flexural vibration, and this movement is hindered by holding, but since there is little expansion and contraction near the neutral axis (neutral plane) of flexural vibration, the vicinity of the neutral axis. By holding, it is possible to reduce the effect of holding on vibration.

(Embodiment 6) In this embodiment, a vibrating body is held near the flexural vibration node. Figure 6
FIG. 6A is a side view of the rectangular columnar vibrating body in a non-vibrating state, and FIG. 6B is a side view of the deflecting vibrating body. The line indicated by 62a drawn in the center of the vibrating body 61 in FIG. 6A is a surface that does not expand or contract due to flexural vibration, that is, the neutral axis (neutral surface) when viewed from the side with respect to the amplitude of flexural vibration. Indicates. When the flexural vibration of the primary mode is excited in the vibrating body 61, the vibrating body 61 is deformed at a certain point as shown in FIG. At this time, the neutral shaft 6 before deformation
Comparing 2a and the neutral shaft 62b after the deformation, it can be seen that there is a portion which is hardly displaced before and after the deformation.
This portion is always kept at a constant position even during vibration if it is a flexural vibration of the same order with the same vibrating body. That is, this portion is a portion called a vibration node. In the vicinity of the vibration nodes 63a and 63b, the vibrating body holding portion 64a,
By holding the vibrating body 61 by 64b, the influence of the holding on the flexural vibration can be reduced as much as possible. In addition, in addition, by holding in the vicinity of the neutral axis, it is possible to reduce the influence on expansion and contraction on the vibrating surface.

On the contrary, FIG. 6C shows a bad example. That is, the vibrating body 6 is placed at a position away from the node.
1 is held by the vibrating body holding portion 64, and the amplitude of flexural vibration is significantly reduced.

The above-mentioned various methods can be appropriately combined and used as necessary, and by doing so, a further great effect can be obtained. Needless to say, the effect does not depend on the shape of the vibrating body as long as it uses flexural vibration.

[0033]

As described above, according to the ultrasonic actuator of claim 1 or claim 2 of the present invention, since the vibrating body is held by point contact or line contact, the holding contact area is smaller than that of the conventional example. It is possible to significantly reduce the amplitude of flexural vibration, and to effectively suppress the decrease in the amplitude of flexural vibration.

According to the ultrasonic actuator of the third aspect, since the vibrating body is held via the cushioning material, it is possible to reduce the influence on the flexural vibration even if the vibrating body is held in surface contact.

According to the ultrasonic actuator of the fourth aspect, by holding the vibrating body in the hole processing portion or groove processing portion formed therein, it becomes possible to hold the vibrating vibration in the vicinity of the neutral axis, and to expand and contract the vibrating body surface. The effect on flexural vibration can be reduced without disturbing movement.

According to the ultrasonic actuator of the fifth aspect, since the vibrating body is held in the vicinity of the flexural vibration node, it is possible to sufficiently suppress the influence on the flexural vibration and obtain a large driving force.

[Brief description of drawings]

FIG. 1 is a front view of an ultrasonic actuator according to a first embodiment of the present invention, which is related to a point contact method, as seen from the longitudinal direction of a vibrating body.

FIG. 2 is a front view of an ultrasonic actuator according to a second embodiment of the point contact system of the present invention as viewed from the longitudinal direction of a vibrating body.

FIG. 3 (a) is a front view of an ultrasonic actuator according to a third embodiment of the line contact method of the present invention, as seen from the longitudinal direction of a vibrating body. It is an expanded sectional view of the AA line arrow in (a) of a figure (b).

FIG. 4 is a front view of an ultrasonic actuator according to a fourth embodiment of the cushioning material system of the present invention as viewed from the longitudinal direction of a vibrating body.

FIG. 5 is a front view of an ultrasonic actuator according to a fifth embodiment of the machining method of the present invention as seen from the longitudinal direction of a vibrating body.

FIG. 6 (a) is a side view showing an ultrasonic actuator according to a sixth embodiment of the method for holding the vicinity of a node of the present invention, showing a state in which the vibrating body is stationary. (B) It is a side view which shows the state which the vibrating body was bending. (C) It is a side view which shows the case where a vibrating body is hold | maintained in places other than a node part.

FIG. 7A is a perspective view showing a state in which no electric field is applied to the vibrating body in the ultrasonic actuator of the conventional example. (B) It is a perspective view which shows the state which applied the electric field to the vibration body in the ultrasonic actuator of a prior art example, and was bent. (C) It is a front view which shows the rotational motion by the bending of the vibrating body in the ultrasonic actuator of a prior art example.

FIG. 8 is a perspective view showing the configuration of a conventional ultrasonic actuator utilizing flexural vibration.

[Explanation of symbols]

 11 ... Vibrating body 12a, 12b ... Vibrating body holding portion 13a to 13d ... Conical protrusion 14a, 14b ... Holding screw 21 ... Vibrating body 22a, 22b ... Vibrating body holding portion 23a to 23d. Protrusions 24a, 24b ... Retaining screw 31 ... Vibrating body 32a, 32b ... Vibrating body holding portion 33a, 33b ... Tapered protrusion 34a, 34b ... Retaining screw 41 ... Vibrating body 42a, 42b. Vibrating body holding portion 43a, 43b ... Buffer material 44a, 44b ... Holding screw 51 ... Vibrating body 52a, 52b ... Vibrating body holding portion 53a, 53b ... Holding pin 54a, 54b .. Holding screw 61 ... Vibrators 62a, 62b ... Neutral shafts 63a, 63b ... Nodes 64a, 64b ... Vibrator holders

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Kawasaki 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (5)

[Claims] 1. An ultrasonic actuator for driving a moving body, which is placed in pressure contact with the vibrating body by exciting elastic vibration in a vibrating body composed of a piezoelectric body and an elastic body, wherein a rod-shaped vibrating body is used as the vibrating body. An ultrasonic actuator, characterized in that a vibrating body is adopted, flexural vibration is adopted as elastic vibration, and the vibrating body is held in point contact with a vibrating body holding portion. 2. An ultrasonic actuator for driving a moving body, which is placed in pressure contact with the vibrating body by exciting elastic vibration in the vibrating body composed of a piezoelectric body and an elastic body, wherein a rod-shaped vibrating body is used as the vibrating body. An ultrasonic actuator, characterized in that a vibrating body is adopted, flexural vibration is adopted as elastic vibration, and the vibrating body is held in line contact with a vibrating body holding portion. 3. An ultrasonic actuator for driving a moving body, which is placed in pressure contact with the vibrating body by exciting elastic vibration in a vibrating body composed of a piezoelectric body and an elastic body, wherein a rod-shaped vibrating body is used as the vibrating body. An ultrasonic actuator characterized in that a vibrating body is adopted, flexural vibration is adopted as elastic vibration, and the vibrating body is held with a cushioning material interposed between the vibrating body and a vibrating body holding portion. 4. An ultrasonic actuator for driving a moving body, which is placed in pressure contact with the vibrating body by exciting elastic vibration in the vibrating body composed of a piezoelectric body and an elastic body, wherein a rod-shaped vibrating body is used as the vibrating body. A vibrating body is adopted, and flexural vibration is adopted as elastic vibration, and the vibrating body is holed or grooved, and the vibrating body is held by the vibrating body holding section via the holed or grooved section. An ultrasonic actuator characterized by being provided. 5. An ultrasonic actuator for driving a moving body, which is placed in pressure contact with a vibrating body by exciting elastic vibration in the vibrating body composed of a piezoelectric body and an elastic body, wherein a rod-shaped vibrating body is used as the vibrating body. The vibrating body is adopted, and the flexural vibration is adopted as the elastic vibration, and the vibrating body is held by the vibrating body holding portion in the vicinity of the node of the flexural vibration in the vibrating body. 4. The ultrasonic actuator according to any one of 4 to 4.