JPH1094277A - Vibration actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the thickness and size by a method wherein a driving-force fetch part is installed and a part which comes into contact with a relative motion member is formed so as to be tilted respectively to a first vibration direction and a second vibration direction. SOLUTION: An elastic body 12 is nearly rectangular flat boardlike, and both edges 12a, 12b in the length direction are formed to be slopes at a prescribed angle α with reference to a plane part. At this time, when an AC voltage is applied across piezoelectric bodies 13a, 13b, an oval motion is generated at driving-force fetch parts 12a, 12b. Then, when the driving-force fetch parts 12a, 12b which are formed at the elastic body 12 and a moving element are pressurized so as to be brought into contact, driving forces are propagated to the moving element from the driving-force fetch parts 12a, 12b due to the friction of both, and the moving elements is turned and driven. Thereby, an ultrasonic actuator 10 can be made thin as a whole, and it is possible to obtain the ultrasonic actuator whose output efficiency is excellent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a first vibration and a second vibration.
The present invention relates to a vibration actuator that includes a vibrator that generates vibration and a relative motion member that comes into pressure contact with the vibrator, and that generates a relative motion between the vibrator and the relative motion member.

[0002]

2. Description of the Related Art Conventionally, a driving voltage is applied to a vibrator constituted by an elastic body and an electromechanical transducer mounted on the elastic body to perform first vibration (bending vibration) and second vibration (longitudinal vibration). There is known a vibration actuator that generates a relative motion between a relative motion member that presses and contacts the vibrator by generating the elliptical motion harmoniously and generating an elliptical motion on the surface of the vibrator.

[0003] As such a vibration actuator,
For example, "Piezoelectric linear motor for optical pickup movement" (Mr. Yoshiro Tomikawa et al .: Proceedings of the 5th Dynamic Symposium on Electromagnetic Force, pp. 393-398)
Page), the results of the analysis on the configuration and load characteristics are described in detail.

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. 6 shows such a vibration actuator 1.
It is a front view which shows the structure of an example of 00. Thin plate-like piezoelectric members 102a and 102b made of PZT (lead zirconate titanate) are attached to one flat surface of the rectangular plate-like elastic member 101 by bonding. The piezoelectric bodies 102a and 102b
The drive voltage is applied to each of the elastic members 10.
First, a fourth-order bending vibration in the longitudinal direction and a first-order longitudinal vibration expanding and contracting in the longitudinal direction are generated. Two antinode positions in the generated fourth-order bending vibration on the other flat surface of the elastic body 101 function as the driving force extracting portions 101a and 101b. The driving force extracting portions 101a and 101b include an elastic body 1
Elliptic motion, which is a composite vibration of the bending vibration and the longitudinal vibration, occurs at 01.

In the example shown in FIG. 6, a vibrator 103 is constituted by an elastic body 101 and piezoelectric bodies 102a and 102b. In this vibration actuator 100, the elastic body 101
Are designed so that the natural frequencies of the fourth-order bending vibration and the first-order longitudinal vibration that occur in the first and second longitudinal vibrations are very close to each other.
Therefore, the two vibrations can be generated in a harmonious state by applying two phases of AC voltages having frequencies close to the respective natural frequencies.

Driving force take-out portion 1 formed on elastic body 101
The end faces of 01a and 101b are formed in a plane shape in a direction orthogonal to the vibration direction (vertical direction in the drawing) of the bending vibration generated in the elastic body 101.

The driving force take-out portions 101a, 101b
Roller-like movers 104a, 104 as relative movement members
b makes contact while being rotatably supported. Further, the elastic body 101 is supported by the support member 10 held by the fixing portion 105.
6 and an urging member 107 installed between the elastic body 101 and the fixing portion 105. As a result, the elastic body 101 is pressed against the moving elements 104a and 104b with appropriate pressure.

In this manner, the elliptical motion generated in the driving force take-out portions 101a and 101b of the elastic body 101 causes the moving element 1
04a, 104b, the elastic body 101 and the moving element 1
Relative motion is generated between the first and second substrates 04a and 104b.

The vibration actuator 100 is
It is designed such that the natural frequencies of the bending vibration and the longitudinal vibration generated in the elastic body 101 are very close to each other. Therefore, by applying an AC voltage having a frequency close to the two natural frequencies to each of the piezoelectric bodies 104a and 104b, it is possible to harmonize the bending vibration and the longitudinal vibration (to generate an elliptic motion which is a synthetic vibration). , Elastic body 10
1 and the moving elements 104a and 104b can generate a relative motion.

As described above, the conventional vibration actuator 10
0, the moving element 10 of the driving force extraction units 101a and 101b
The contact surfaces with 4a and 104b are provided so as to be directed in a direction parallel or perpendicular to the respective vibration directions of the bending vibration and the longitudinal vibration generated in the elastic body 101.

[0012]

However, in the conventional vibration actuator, the driving force extracting portions 101a and 101b are provided on one plane of the elastic body 101.
Since the movable elements 104a and 104b are brought into contact with the movable elements 1a and 101b, the thickness of the entire vibration actuator 100 is increased by the provision of the movable elements 104a and 104b.
For this reason, there is a problem that a great advantage of the vibration actuator 100 that the size can be reduced is lost.

As a means for forming the driving force take-out portion while suppressing the thickness of the vibration actuator 100 as much as possible, a means in which the drive force take-out portion is provided on the side surface of the elastic body 101 may be considered. FIG. 7 is a front view showing the configuration of the vibration actuator 200 using such means.

According to the vibration actuator 200 shown in FIG. 7, the elastic member 101 and the driving force extracting portions 101c and 101d are provided.
Although the vibration actuator 200 is certainly thinner in the thickness direction due to the positional relationship with the moving members 104a,
4b uses the bending vibration to drive the elastic body 10b.
Longitudinal vibration will be used for intermittent driving force between the motor 1 and the moving elements 104a and 104b. Therefore, the moving element 104
a, 104b is the vibration direction of the longitudinal vibration (left-right direction on the drawing)
It is necessary to provide a mechanism for moving the object.

In the vibration actuator 200 shown in FIG. 7, the moving elements 104a and 104b are connected by a spring 108, and the moving elements 104a and 104b are
4b is moved. Therefore, there is a problem that the entire structure of the vibration actuator 200 is complicated.

Further, in general, in the vibration actuator having the structure shown in FIGS. 6 and 7, the driving force extracting portions 101a,
The elliptical motion generated in 101b (101c, 101d) is at a certain angle α (0 ° <
(<90 °). Therefore, the major axis or minor axis of the elliptical motion generated in the elastic body 101 does not coincide with the contact surface of the driving force extraction units 101a, 101b (101c, 101d) with the moving elements 104a, 104b. Therefore, there is a problem that the elliptical motion generated in the elastic body 101 is not transmitted to the moving elements 104a and 104b without waste, and the driving force extraction efficiency is lower than an ideal state.

[0017]

According to a first aspect of the present invention, there is provided a vibrator provided with a driving force extracting unit, and a vibrator pressurized through the driving force extracting unit. A relative motion member that contacts in a state, and generates a first vibration and a second vibration in the vibrator to generate a combined motion thereof, thereby generating a relative motion between the vibrator and the relative motion member. An actuator, wherein a driving force extracting portion is provided, and a portion that comes into contact with the relative motion member is formed so as to be inclined with respect to the respective vibration directions of the first vibration and the second vibration. I do.

According to a second aspect of the present invention, in the vibration actuator according to the first aspect, the contact surface of the driving force extracting portion with the relative motion member is in a direction substantially parallel to the major axis direction or the minor axis direction of the elliptical motion. , Is formed.

The third aspect of the present invention is the first or second aspect.
In the vibration actuator described in the above, the vibrator and the relative motion member are pressed in a direction substantially the same as the major axis direction of the elliptical motion, and the minor axis direction of the elliptical motion is substantially the same as the direction of the relative motion. Direction.

According to a fourth aspect of the present invention, in the vibration actuator according to the third aspect, the driving force extracting portion is formed on one plane of the vibrator or on a side surface of the vibrator.

According to a fifth aspect of the present invention, there is provided the first to fourth aspects.
In the vibration actuator described in any one of the above, the first vibration is a bending vibration and the second vibration is a longitudinal vibration.

[0022]

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 structure of the ultrasonic actuator body according to the first embodiment of the present invention, and FIG. 2 is a front view showing the structure of the ultrasonic actuator. FIG. 3 is a front view showing a state in which the ultrasonic actuator is fixedly held on a fixed portion of the mounted device.

As shown in FIGS. 1 to 3, a vibrator 11 forming a main body of an ultrasonic actuator 10 according to the present embodiment.
Is a rectangular flat plate-like elastic body 12, and four piezoelectric bodies 12 mounted on one plane of this elastic body 12 by, for example, bonding.
a, 12b, 12p, and 12p '.

The elastic body 12 is made of an elastic material such as a metal material or a plastic material. The elastic body 12 is formed in a substantially rectangular flat plate shape, and has both end faces 12a, 1a in the longitudinal direction.
2b is a predetermined angle α (α: more than 0 ° 90
°, more than 90 ° and less than 180 °). In the ultrasonic actuator 10 according to the present embodiment, the inclined surfaces 12a and 12b are used as a driving force extracting unit.

In the center of the elastic body 12 in the longitudinal direction,
Grooves 12c are provided on the four surfaces, and small cross-sectional area portions are formed. The groove 12 c is engaged with a connecting member 14 described later, so that the elastic body 12
Is formed in order to prevent misalignment.

The piezoelectric bodies 13a and 13b mounted on one plane of the elastic body 12 have two phases electrically different from each other by 90 degrees.
A phase AC voltage is applied. Further, the piezoelectric bodies 13p, 13
p 'is a piezoelectric body for monitoring the state of vibration generated in the elastic body 12, and is connected to a control circuit described later with reference to FIG. The elastic body 12 is connected to the GND potential.

In the vibrator 11 of the ultrasonic actuator 10 configured as described above, the piezoelectric bodies 13a, 13b
By applying two-phase AC voltages having phases electrically different from each other by 90 degrees, the driving force extracting portions 12a and 12
Elliptic motion occurs in b.

The elastic body 12 is fixed and held by a connecting member 14 installed in a housing 15 of a mounted device, and a pressing spring 16 is mounted between the housing 15 and the vibrator 11. You. Thereby, the elastic body 12
The driving force take-out portions 12a, 12b are pressed by the moving members 17a, 17b, which are relative moving members.

As described above, the driving force extracting portions 12a, 1
2b, a roller-shaped moving element 17 as a relative moving member is provided.
a and 17b are brought into pressure contact. Movers 17a, 17b
Is rotatably supported by a shaft support mechanism (not shown).

As described above, by bringing the driving force extracting portions 12a, 12b formed on the elastic body 12 into pressure contact with the moving elements 17a, 17b, the friction between the two causes the driving force extracting portions 12a, 12b to drive. Force is moving element 17a, 17b
And the movable elements 17a and 17b are rotationally driven.

FIG. 4 is a block diagram showing a drive circuit 20 of the ultrasonic actuator 10 according to the present embodiment. The drive circuit 20 includes an oscillator 21 that oscillates a drive signal, and a phase shifter 2 that converts the drive signal into a signal having a phase difference of (π / 2).
2, an amplifier 23 for amplifying the drive signal input to the piezoelectric body 13a, and an amplifier 24 for amplifying the converted drive signal for amplifying the drive signal input to the piezoelectric body 13b.

The vibration displacement detected by the piezoelectric bodies 13p and 13p 'is sent to the control circuit 25 as an electric signal. The control circuit 25 sends a correction signal to the oscillator 21 based on the detected displacement amount, and the drive signal output from the oscillator 21 is optimized.

The piezoelectric circuit 1 is controlled by the control circuit 20 as described above.
By applying an AC voltage having a phase difference of 90 ° to the electrodes 3a and 13b, bending vibration and longitudinal vibration are generated in the elastic body 12 in harmony. This occurs at the driving force take-out portions 12a and 12b.

According to the ultrasonic actuator 10 of the present embodiment, the driving force output portions 12a,
Numeral 12b is not the horizontal direction or the vertical direction of the vibration direction of the bending vibration or the longitudinal vibration generated in the elastic body 12, and is directed in the minor axis direction of the elliptical motion in the driving force output portions 12a and 12b. Therefore, the pressing direction between the driving force extracting portions 12a and 12b of the elastic body 12 and the moving elements 17a and 17b is the major axis direction of the elliptical motion, and the driving force of the ultrasonic actuator 10 is improved. In addition, the short axis direction of the elliptical motion becomes the driving direction, which is suitable for low-speed driving.

As described above, according to the ultrasonic actuator 10 of the present embodiment, the movable element 17 is provided on the side of the elastic body 12.
Since the a and 17b can be arranged, the overall thickness of the ultrasonic actuator 10 can be reduced. In addition, it is possible to realize an ultrasonic actuator excellent in output output efficiency.

(Second Embodiment) FIG. 5 is a front view showing the structure of an ultrasonic actuator 10-1 according to a second embodiment. The ultrasonic actuator 10-
1 is common to most parts in the first embodiment, and therefore, the same parts are denoted by the same reference numerals in the drawings to omit redundant description, and only different parts will be described.

As shown in FIG. 5, in the ultrasonic actuator 10-1 of the second embodiment, the elastic member 12 is not supported by the housing 15, but the connecting member is formed by the housing 15-1 having a U-shaped cross section. The elastic body 12 is supported via the pressure spring 14 and the pressure spring 16 in a state of being urged toward the opening of the housing 15-1. Also, the housing 15-
Rollers 17a, which are moving elements,
17b is rotatably supported.

In this embodiment, the rollers 17a, 17a
The driving force take-out portions 12a and 12b of the elastic body 12 are in pressure contact with b, and the elliptical motion generated in the elastic body 12 is transmitted to the rollers 17a and 17b.

The ultrasonic actuator 10-1 is fixed to a fixed surface 18 as a relative moving member via rollers 17a and 17b.
Mounted on top. Therefore, the ultrasonic actuator 10-1 can move on the fixed surface 18 by the vibration generated in the elastic body 12.

(Modification) In each of the embodiments described in detail above, an ultrasonic actuator utilizing an ultrasonic vibration region is taken as an example of the vibration actuator. However, the vibration actuator according to the present invention has such an aspect. The present invention is not limited thereto, and the present invention can be equally applied to a vibration actuator using another vibration region.

Further, in each embodiment, the ultrasonic actuator using the vibrator using the bending fourth-order vibration as the first vibration and the longitudinal primary vibration as the second vibration is described as an example. Such a vibration actuator is not limited to such an embodiment, and is equally applicable to an ultrasonic actuator utilizing other vibrations.

Further, in the description of each embodiment, the driving force extracting portion is formed on the side surface of the vibrator. However, the vibration actuator according to the present invention is not limited to such a mode, and the piezoelectric member of the vibrator is not limited to such a mode. It may be formed on the non-mounting surface side. In this case, a form in which the driving force extracting portion is formed in a protruding shape on the plane on the piezoelectric body non-mounting surface side of the vibrator, and an inclined surface is formed on the contact surface with the relative motion member which is the bottom surface of the driving force extracting portion. Examples can be given.

Further, in the description of each embodiment, a 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 electric energy is converted into mechanical displacement. Anything that can be converted may be used. For example, an electrostrictive element or a magnetostrictive element can be exemplified.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a structure of an ultrasonic actuator main body according to a first embodiment of the present invention.

FIG. 2 is a front view showing the structure of the ultrasonic actuator according to the first embodiment.

FIG. 3 is a front view showing a state in which the ultrasonic actuator according to the first embodiment is fixedly held on a fixing portion of the mounted device.

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

FIG. 5 is a front view illustrating a structure of an ultrasonic actuator according to a second embodiment.

FIG. 6 is a front view showing a configuration of an example of a conventional vibration actuator.

FIG. 7 is a front view showing a means for forming a driving force extracting portion in a conventional vibration actuator while suppressing the thickness of the vibration actuator as much as possible.

[Explanation of symbols]

10, 10-1 Ultrasonic actuator (vibration actuator) 11 Vibrator 12 Elastic body 12a, 12b Driving force take-out portion (both end surfaces, inclined surface) 12c Groove portion 13a, 13b Driving piezoelectric body 13p, 13p 'Vibration monitoring piezoelectric body DESCRIPTION OF SYMBOLS 14 Support member 15, 15-1 Housing 16 Pressure spring 17a, 17b Moving element (relative moving member) 18 Fixed surface 20 Drive circuit 21 Oscillator 22 Phase shifter 23 Amplifier 24 Amplifier

Claims (5)

[Claims] 1. A vibrator provided with a driving force take-out portion, and a relative motion member which comes into contact with the vibrator while being pressed through the driving force take-out portion, wherein the vibrator is provided with a first vibration A vibration actuator that generates a relative motion between the vibrator and the relative motion member by generating a combined motion by generating the second vibration and the driving force extracting unit. And a portion that contacts the relative motion member is formed so as to be inclined with respect to the respective vibration directions of the first vibration and the second vibration. 2. The vibration actuator according to claim 1, wherein the contact surface is formed in a direction substantially parallel to a major axis direction or a minor axis direction of the elliptical motion. 3. The vibration actuator according to claim 1, wherein the vibrator and the relative motion member are pressed in a direction substantially the same as a major axis direction of the elliptical motion, and A minor axis direction of the elliptical motion is substantially the same as the direction of the relative motion. 4. The vibration actuator according to claim 3, wherein the driving force output portion is formed on one plane of the vibrator or on a side surface of the vibrator. 5. The method according to claim 1, wherein:
In the vibration actuator described in the paragraph, the first vibration is a bending vibration, and the second vibration is a longitudinal vibration.