JPH1014263A - Oscillation actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that the positional control of an body becomes difficult due to shaking by providing members for supporting the elastic body at a plurality of nodes of bending oscillation occurring in the elastic body or the vicinity thereof. SOLUTION: The joints between supporting members 4a, 4b and an elastic member 2 are formed as narrow constricted parts 5a, 5b, extending in the longitudinal direction of the elastic member. The constricted part 5a, 5b functions as a rigidity lowering part for the bending oscillation or the longitudinal osciliation, occurring in the elastic member 2 in the amplitude direction. Consequently, the oscillation damping through the supporting members 4a, 4b can be suppressed for not only the bending oscillation but also the longitudinal oscillation. Furthermore, the elastic member 2 can be protected against torsion, because it is supported at a plurality of nodes. An ultrasonic actuator 1 is fixed to the fixing part of an objective apparatus through the supporting members 4a, 4b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromechanical transducer mounted on an elastic body for generating longitudinal vibration and bending vibration in harmony, and which is in pressure contact with the elastic body. The present invention relates to a vibration actuator that generates a relative motion with a moving member.

[0002]

2. Description of the Related Art Conventionally, a drive voltage is applied to an elastic body having a piezoelectric body, which is an electromechanical transducer, to generate a longitudinal vibration and a bending vibration harmoniously, thereby generating an elliptical motion on the surface of the elastic body. There is known a vibration actuator which generates a relative motion between the elastic member and a relative motion member which comes into pressure contact with an elastic body.

Such a vibration actuator is described in, for example, "Piezoelectric Linear Motor for Moving Optical Pickup" (Yoshiaki Tomikawa et al .: Proceedings of the 5th Dynamic Symposium on Electromagnetic Force, pp. 393-398). page)
Describes in detail the configuration and the analysis results relating to the load characteristics.

Also, a new ultrasonic motor (co-authored by Mr. Sadayuki Ueba and Mr. Yoshiro Tomikawa, published by Trikeps, pages 145 to 146)
Page) discloses a self-propelled device using the vibration actuator.

FIG. 7 shows such a vibration actuator 1.
FIG. 8 is a perspective view showing an example of the configuration of the 00, and FIG. 8 is a top view thereof. Thin piezoelectric members 103a and 103b made of PZT (lead zirconate titanate) are bonded to one flat surface of the rectangular flat elastic member 101 by bonding. The piezoelectric bodies 103a and 103b are expanded and contracted in the longitudinal direction by the elastic body 101 when a driving voltage is applied.
A next longitudinal vibration and a fourth-order bending vibration in the longitudinal direction are generated. Driving force take-out portions 101a and 101b are formed on the other flat surface of the elastic body 101 at two antinode positions in the generated fourth-order bending vibration. On the end faces of the driving force extracting portions 101a and 101b, an elliptical motion which is a combined vibration of the longitudinal vibration and the bending vibration is generated.

[0006] These driving force extraction units 101a, 101b
A moving element, which is a relative moving member (not shown), comes into pressure contact with the end face of the moving element. Accordingly, relative motion occurs between the elastic body 101 and the moving element due to the elliptical motion described above.

The vibration actuator 100 is designed so that the natural frequencies of the longitudinal vibration and the bending vibration generated in the elastic body 101 are very close to each other. Thus, by applying an AC voltage having a frequency close to the two natural frequencies to the piezoelectric bodies 103a and 103b, respectively,
The longitudinal vibration and the bending vibration can be generated in a harmonized state, and a relative motion can be generated between the elastic body 101 and the moving element.

By the way, in order to support the elastic body 101 and bring it into pressure contact with the relative motion member, a semicircular cutout 104 is formed at the center in the length direction on the side surface of the elastic body 101.
a, 104b are formed, and these notches 1
The elastic body 1 is provided by a rectangular flat support frame 102 having pins 102a and 102b fitted to the support members 04a and 104b.
By restricting the position of the elastic member 101 in the longitudinal direction, the elastic body 101 is supported.

[0009]

As described above, the elastic body 1
01 is a notch 104a, 1 provided in the elastic body 101.
04b and pins 102a, 102 formed on the support frame 102.
It is supported using the fitting with 2b. However, since there is an unavoidable gap between the notches 104a, 104b and the pins 102a, 102b, there has been a problem that rattling occurs in the relative movement direction. Therefore, there is a problem that the position control of the elastic body 101 becomes difficult due to the backlash.

Further, since a reaction force acts on the elastic body from the moving element, there is another problem that the elastic body 101 is displaced in an in-plane direction and an out-of-plane direction.

[0011]

According to a first aspect of the present invention, there is provided an electromechanical transducer which is attached to an elastic body and which generates a primary or more longitudinal vibration and a secondary or more bending vibration in a harmonic manner. A vibration actuator that generates relative motion between a relative motion member that comes into pressure contact with the elastic body, and supports the elastic body at or near a plurality of node positions of bending vibration generated in the elastic body. The support members are provided respectively.

According to a second aspect of the present invention, in the vibration actuator according to the first aspect, the support member has a reduced rigidity portion in the amplitude direction of the longitudinal vibration.

[0013] The invention of claim 3 is claim 1 or claim 2.
In the vibration actuator described in (1), all or some of the plurality of support members are connected to each other.

According to a fourth aspect of the present invention, there is provided the first to third aspects.
In the vibration actuator described in any one of the above, the plurality of support members are provided at symmetrical positions with respect to the length direction and / or the width direction and / or the thickness direction of the elastic body.

[0015]

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. In the following description of each embodiment, an ultrasonic actuator using an ultrasonic vibration region is used as an example of the vibration actuator.

FIG. 1 is a perspective view showing the ultrasonic actuator 1 and its supporting members 4a and 4b in this embodiment, and FIG. 2 is a top view of the ultrasonic actuator 1 and its supporting members 4a and 4b shown in FIG. FIG. Further, FIG.
(A) is a side view of the ultrasonic actuator 1 and its supporting members 4a and 4b shown in FIG. 1, and FIG. 3 (b) is a displacement of bending vibration generated in the elastic body 2 of the ultrasonic actuator 1 shown in FIG. It is explanatory drawing which shows an example.

The main body of the ultrasonic actuator 1 according to the present embodiment is configured in exactly the same manner as the ultrasonic actuator 100 shown in FIGS.
The ultrasonic actuator 1 includes a rectangular plate-shaped elastic body 2,
The elastic body 2 includes piezoelectric bodies 3a and 3b, which are electromechanical transducers that are attached to one flat surface of the elastic body 2 by adhesion and generate longitudinal vibration and bending vibration in the elastic body 2 in harmony. Piezoelectric body 3
AC voltages having phases that are electrically different from each other by 90 ° are applied to a and 3b.

Although the reference numerals 3p and 3p 'in the figure are also piezoelectric members, these are piezoelectric members for monitoring the vibration state generated in the elastic member 2, and are controlled by a control described later with reference to FIG. Connected to circuit 15. The main body of the elastic body 2 is G
Connected to ND potential.

The other two planes (the positions X and Y in FIG. 3B) of the antinode position of the fourth-order bending vibration on the other plane of the elastic body 2 take out the driving force in a protruding manner. Parts 2a, 2b
Is formed.

FIG. 4 is a block diagram showing a drive circuit 10 of the ultrasonic actuator 1 according to the present embodiment. The drive circuit 10 includes an oscillator 11 that oscillates a drive signal, and a phase shifter 12 that converts the drive signal into a signal having a phase difference of (π / 2).
And an amplifier 1 for amplifying a drive signal input to the piezoelectric body 3a
3 and an amplifier 14 for amplifying the converted drive signal input to the piezoelectric body 3b.

The vibration displacement detected by the piezoelectric bodies 3p and 3p 'is sent to the control circuit 15 as an electric signal. The control circuit 15 sends a correction signal to the oscillator 11 based on the detected displacement amount, and the drive signal output from the oscillator 11 is optimized.

With such a drive circuit 10, the piezoelectric body 3
By applying an AC voltage having a phase difference of 90 ° to the a and 3b, a longitudinal vibration and a bending vibration are generated harmoniously in the elastic body 2, and an elliptic motion which is a composite of these vibrations is generated.
It is generated on the end faces of the driving force extracting portions 2a and 2b of the elastic body 2.
Due to this elliptical motion, a relative motion member (not shown) which comes into pressure contact with the driving force take-out portions 2a and 2b makes a one-dimensional relative motion.

In FIG. 1 to FIG. 3, two nodes (positions Z ₁ and Z ₂ in FIG. 3 (b)) of the bending vibration generated on the two side surfaces 2c and 2d of the elastic body 2 have elasticity. Body 2
Are installed in a direction parallel to the elastic body width direction. This installation position is a symmetrical position in each of the length direction, the thickness direction, and the width direction of the elastic body 2. As shown in FIG. 3A, the installation position of the support members 4a and 4b is set at the node position Z of the bending vibration.
₁ and Z ₂ , it is possible to support the bending vibration generated in the elastic body 2 without attenuating it.

In the present embodiment, the connecting portions of the support members 4a and 4b with the elastic body 2 are formed as narrow portions 5a and 5b whose width is narrow in the longitudinal direction of the elastic body. Constriction 5a,
5b functions as a stiffness reduction section in the amplitude direction (longitudinal direction of the elastic body) of each of the bending vibration and the longitudinal vibration generated in the elastic body 2. Therefore, the vibration damping due to the support of the support members 4a and 4b can be suppressed not only for the bending vibration but also for the longitudinal vibration. Further, in the present embodiment, since the elastic body 2 is supported at a plurality of joint positions, it is possible to prevent the elastic body 2 from being twisted.

As described above, the ultrasonic actuator 1 of the present embodiment is fixed to the fixed portion of the device to be mounted via the support members 4a and 4b. FIG. 5 shows an ultrasonic actuator 1 according to the present embodiment, which is a plate-like material 2 which is a mounting target device.
FIG. 7 is a cross-sectional view illustrating a state in which the device is incorporated in a transfer device 21 of No. 0;

The housing 22 of the transfer device 21 is a frame having a groove-shaped cross section. Inner surface bottom 2 of housing 22
2a, the bearing holding base 23 is directed toward the opening,
For example, it is fixed by being adhered. The bearing holder 23 holds the bearing 24. The bearing holder 23 may be formed integrally with the housing 22.

On the other hand, a movable bearing holder 25 having an L-shaped cross section is disposed on the inner bottom surface 22a of the housing 22 so as to be reciprocally movable in the horizontal direction in the drawing. The movable bearing holder 25 is provided with a bolt through hole 25a extending in the left-right direction in the drawing. A headed bolt 26 is inserted into the bolt through hole 25 a, and the tip of the headed bolt 26 is screwed to one vertical wall portion 22 b of the housing 22. Further, a coil spring 27 is attached to a portion between the vertical wall portion 22b and the movable bearing holder 25 by being fitted into a headed bolt 26. Due to the spring force of the coil spring 27, the movable bearing holder 25 is urged toward the other vertical wall portion 22c of the housing 22.

At the upper end of the movable bearing holder 25, a bearing 28 is held so as to face the vertical wall portion 22c. A space 29 facing the inside is formed in the vertical wall portion 22c, and the ultrasonic actuator 1 of the present embodiment is installed so that the piezoelectric body 3 is accommodated in the space 29. The ultrasonic actuator 1 is shown in FIG.
, Through holes are provided in the circles of the four support members 4a, 4a, 4b, 4b, and four bolts 30a, 30b make use of these four through holes to the vertical wall portion 22c. Fixed.

A bearing 24 is in contact with the bottom surface of the plate member 20 having a rectangular cross section, and a bearing 28 is in contact with one side surface. Thereby, the plate-shaped material 20 is guided in a direction orthogonal to the drawing.

Further, on another side surface of the plate member 20, an ultrasonic actuator 1 fixed to the vertical wall portion 22c is provided.
Drive force take-out portions 2a and 2b come into contact with each other. The plate member 20 is
Due to the spring force of the coil spring 27, the bearing 28
Are applied to the driving force take-out portions 2a and 2b with a desired pressing force.

When the ultrasonic actuator 1 is driven in this state, the plate member 20 receives a driving force in a direction orthogonal to the drawing due to the elliptical motion generated in the driving force extracting portions 2a and 2b. The plate material 20 is transported by this driving force. By inputting a driving voltage opposite to this to the ultrasonic actuator 1, the plate-shaped material 20 is conveyed in the opposite direction.

(Second Embodiment) Hereinafter, a second embodiment of the present invention will be described. Note that the following description of the second embodiment is as follows.
Only the parts different from those of the first embodiment will be described, and the common parts will be denoted by the same reference numerals in the drawings, and the description thereof will be appropriately omitted.

FIG. 6A is a top view and a side view of the ultrasonic actuator 1-1 and the holding members 6a and 6b of the second embodiment, and FIG. 6B is an ultrasonic actuator 1 of the second embodiment. FIG. 7 is an explanatory diagram showing an example of displacement of bending vibration generated in an elastic body 2 of FIG.

The ultrasonic actuator 1-1 of the present embodiment
Is that the supporting members adjacent to each other are connected to each other to form integral supporting members 6a and 6b.

That is, the support member 6a is connected to the side surface 2c of the elastic body 2 via the two constricted portions 7a, 7a, and the support member 6b is connected to the side surface 2d of the elastic body 2 via the two constricted portions 7b, 7b. Connected. In the first embodiment, the support member is provided with the constricted portions 7a and 7b in order to suppress vibration attenuation.
Is provided to reduce rigidity. Therefore, there is a possibility that the constricted portions 7b, 7b may be deformed due to handling at the time of installation or the like. Thus, in the present embodiment, by connecting adjacent support members, rigidity is increased within a range where vibration damping is not suppressed, and deformation during handling is prevented.

Further, by joining the adjacent support members to each other, the accuracy of the installation position of the support members is improved, and the mounting accuracy of the ultrasonic actuator to the device to be mounted is improved.

(Modification) In the above description of each embodiment, the ultrasonic actuator is used as the vibration actuator. However, the vibration actuator according to the present invention is not limited to only such an embodiment, and other vibration actuators may be used. The same applies to a vibration actuator using a vibration region other than the sound wave region.

Further, in each of the embodiments, the piezoelectric body is used as the electromechanical transducer. However, the vibration actuator according to the present invention is not limited to such a mode, and converts electric energy into mechanical displacement. Anything that can be applied can be equally applied. For example, an electrostrictive element other than the piezoelectric body can be exemplified.

Further, in each embodiment, the support member is installed at a node position of the bending vibration generated in the elastic body, but a slight deviation from the node position is allowed. In other words, it is most desirable to support the joint at the node position in order to suppress the attenuation of the bending vibration as much as possible. However, when the attenuation of the bending vibration is not a problem, the antenna may be installed near the node position.

In the second embodiment, the case where adjacent supporting members are connected to each other has been described. However, the vibration actuator according to the present invention is not limited to such a mode, and may be opposed in the elastic body width direction. Between support members at different positions,
You may comprise so that all the support members may be connected.

Further, in each embodiment, the elastic body is supported at two nodal positions. However, the vibration actuator according to the present invention is not limited to such a mode, and the vibration actuator according to the present invention is not limited to three or more nodal positions. You may make it support at a knot position.

Also, in the description of each embodiment, one elastic body is used.
The vibration actuator that generates the next longitudinal vibration and the fourth-order bending vibration is taken as an example, but the vibration actuator according to the present invention is not limited to such an embodiment, and the m-th (m: natural number) vertical vibration is used. Vibration and nth order (n: natural number of 2 or more)
The same applies to a vibration actuator that generates bending vibration.

In the description of each embodiment, the case where the support member is formed at symmetrical positions in the length direction and the thickness direction of the elastic body is taken as an example. However, the present invention is not limited to these embodiments, and the support is disposed at a position symmetrical with respect to one or more of the elastic body in the length direction, width direction, and thickness direction. I just need.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an ultrasonic actuator and a support member thereof according to a first embodiment.

FIG. 2 is a top view of the ultrasonic actuator and its support member shown in FIG.

3 (a) is a side view of the ultrasonic actuator shown in FIG. 1 and a supporting member thereof, and FIG. 3 (b) is a displacement of bending vibration generated in an elastic body of the ultrasonic actuator shown in FIG. It is explanatory drawing which shows an example.

FIG. 4 is a block diagram illustrating a drive circuit of the ultrasonic actuator according to the first embodiment.

FIG. 5 is a cross-sectional view showing a state in which the ultrasonic actuator according to the first embodiment is incorporated in a plate-like material conveying device.

FIG. 6A is a top view and a side view of an ultrasonic actuator and a support member thereof according to a second embodiment, and FIG. 6B.
FIG. 9 is an explanatory diagram illustrating an example of displacement of bending vibration generated in an elastic body of the ultrasonic actuator according to the second embodiment.

FIG. 7 is a perspective view showing a configuration of an example of a conventional vibration actuator.

FIG. 8 is a top view of the conventional vibration actuator shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultrasonic actuator (vibration actuator) 2 Elastic body 2a, 2b Driving force extraction part 3a, 3b Piezoelectric body (electromechanical conversion element) 4a, 4b Support member 5a, 5b Neck

Claims (4)

[Claims] 1. An elastic body, and an electromechanical transducer mounted on the elastic body for generating first-order or more longitudinal vibration and second-order or more bending vibration in harmony, and pressurizing the elastic body. A vibration actuator that generates relative motion between a contacting relative motion member and a support member that supports the elastic body is provided at or near a plurality of node positions of the bending vibration generated in the elastic body. A vibration actuator characterized in that: 2. The vibration actuator according to claim 1, wherein a rigidity-reducing portion in an amplitude direction of the longitudinal vibration is formed in the support member. 3. The vibration actuator according to claim 1, wherein all or some of the plurality of support members are connected to each other. 4. One of claims 1 to 3
In the vibration actuator described in the paragraph, the plurality of support members are provided at symmetrical positions with respect to a length direction and / or a width direction and / or a thickness direction of the elastic body.