JPH10323061A - Vibration actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove play between a relative motion member and a supporting mechanism. SOLUTION: The actuator is provided with a vibrator 11 which excites longitudinal vibration and bending vibration in a flat plate-shaped or columnar elastic body, and produces elliptic motion in driving force take-out section formed on the elastic body in a specified position; and a supporting mechanism 31 which supports a relative motion member 21 placed almost in parallel with the elastic body on supporting sections 32 on the opposite side to the vibrator 11. The driving force take-out section is brought into contact with the relative motion member 21, thereby causing the relative motion member 21 to perform relative motion. In this case, the supporting mechanism 31 elastically holds the supporting sections 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration actuator that performs relative movement with a relative motion member by applying a force from a vibrator to the relative motion member supported by a support mechanism.

[0002]

2. Description of the Related Art Conventionally, a drive signal is applied to an elastic body on which a piezoelectric body is mounted so as to generate a longitudinal vibration and a bending vibration harmoniously, and to generate an elliptical motion on the surface of the elastic body. 2. Description of the Related Art Vibration actuators for driving a relative motion member that comes into pressure contact with a body are known. For such a vibration actuator, see "Piezoelectric Linear Motor for Moving Optical Pickup" (Yoshiaki Tomikawa et al .: Proceedings of the 5th Dynamic Symposium on Electromagnetic Force, No. 3
(Pages 93 to 398), the analysis results regarding the configuration and the load characteristics are described in detail. Further, a self-propelled device using this vibration actuator is disclosed in a new version of ultrasonic motor (by Sadayuki Ueba and Yoshiro Tomikawa, published by Trikeps, pages 145 to 146).

FIG. 4 is a view showing an example of a conventional vibration actuator. FIG. 4 (a) is a side view thereof, and FIG. 4 (b).
Is a front view, and FIG. 4C is a side view showing a part of a support mechanism of the vibration actuator. As shown in FIG. 4A, the conventional vibration actuator 100 mainly includes a vibrator 110 that drives a relative motion member 120 and a support mechanism 130 that supports the relative motion member.

[0004] A vibrator 110 is composed of two piezoelectric members 114 on a flat elastic member 112 designed so that the natural frequencies of the first-order longitudinal vibration mode and the fourth-order bending vibration mode have very close values. They are joined. Each piezoelectric body 11
4, an AC voltage having a predetermined frequency is applied with a predetermined phase difference. Here, the predetermined frequency refers to the elastic body 112
Are frequencies close to the natural frequencies of the above two vibration modes. The application of the AC voltage causes the piezoelectric body to vibrate, and causes the elastic body 112 to harmoniously generate the above two modes of vibration. A projection 116 is provided at the antinode of the vibration of the fourth bending mode generated in the elastic body. When the elastic body 112 vibrates, an elliptical motion occurs at the tip of the projection 116. The tip of the projection 116 is in contact with the upper surface of the relative movement member 120 at a predetermined pressure, and when the tip performs the above-described elliptical movement, the relative movement member 120 is linearly driven.

[0005] The support mechanism 130 is a mechanism for supporting the relative motion member 120. The support mechanism 130 includes four rollers 132 formed of bearings and the like, and a housing 134 that holds the rollers 132 at the center of rotation.
The four rollers 132 are in contact with the lower surface of the relative motion member 120 to prevent the relative motion member 120 from separating from the elastic projections 116.

[0006]

However, in the above-mentioned conventional vibration actuator, since the roller is fixed to the housing, at the stage of assembling the vibration actuator, the distance between the roller and the vibrator is fixed to a fixed one. Will be done. Therefore, when the lower surface of the relative motion member is supported by four rollers as in the vibration actuator illustrated in FIG. 4, the load of the relative motion member is equally applied to each roller due to a slight error in the arrangement of each roller. In the worst case, play may occur between the roller and the relative motion member. On the other hand, the vibration actuator operates using micron-order vibration performed by the vibrator, and therefore, as described above, there is a difference in the load supported between the rollers, and there is a difference between the relative motion member and the roller. When play occurs between the vibration actuators, there is a problem that the performance of the vibration actuator is not sufficiently exhibited and unpleasant noise is generated during operation.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and is not affected by an error in the position where the supporting portions are arranged. Another object of the present invention is to provide a vibration actuator having a configuration in which a support mechanism appropriately supports a relative motion member.

[0008]

According to a first aspect of the present invention, a flat or columnar elastic body is subjected to longitudinal vibration and bending vibration, and is moved to a predetermined position on the elastic body. A vibrator that generates an elliptical motion in the provided driving force take-out unit, and a support mechanism that supports a relative motion member disposed substantially parallel to the elastic body by a support unit from a side opposite to the vibrator, In a vibration actuator that performs relative movement with the relative movement member by bringing the driving force extracting portion into contact with the relative movement member, the support mechanism elastically holds the support portion. Actuator.

According to a second aspect of the present invention, in the vibration actuator according to the first aspect, the support mechanism guides a movable direction of the support portion in a direction substantially parallel to an amplitude direction of the bending vibration. A vibration actuator having a guide portion. According to a third aspect of the present invention, in the vibration actuator according to the first or second aspect, there are provided two or more support portions, and the support mechanism is configured such that each support portion is resilient by a mechanism independent of each other. The vibration actuator is characterized in that the vibration actuator is held.

According to a fourth aspect of the present invention, there is provided a vibration device which excites a longitudinal vibration and a bending vibration in a flat or columnar elastic body and generates an elliptical motion in a driving force extracting portion provided at a predetermined position of the elastic body. Element, a support mechanism for supporting a relative motion member disposed substantially parallel to the elastic body from a side opposite to the vibrator by a support portion, and for bringing the driving force extracting portion and the relative motion member into pressure contact with each other. And a pressurizing mechanism for applying a pressing force to the vibrator, wherein the supporting mechanism moves the supporting portion in a direction substantially parallel to the amplitude direction of the bending vibration. A vibration actuator, comprising: a guide portion for guiding, and a force acting portion for bringing the support portion into contact with the relative motion member by applying a force in a direction repelling the pressing force to the support portion. That.

According to a fifth aspect of the present invention, in the vibration actuator according to the fourth aspect, the force acting portion is a member having a spring property. According to a sixth aspect of the present invention, in the vibration actuator according to the fourth or fifth aspect, the number of the support portions is two or more, and the support mechanism is a separate force acting portion corresponding to each of the support portions. It is a vibration actuator characterized by having.

According to a seventh aspect of the present invention, there is provided a vibration device which excites a longitudinal vibration and a bending vibration in a flat or columnar elastic body, and generates an elliptical motion in a driving force extracting portion provided at a predetermined position of the elastic body. And a support mechanism for supporting a relative motion member disposed substantially parallel to the elastic body from a side opposite to the vibrator by a support portion, and bringing the driving force extracting portion into contact with the relative motion member. In the vibration actuator that performs relative motion with the relative motion member, the support mechanism includes:
A vibration actuator characterized in that the support portion is held so as to be position-adjustable in a direction substantially parallel to the amplitude direction of the bending vibration. According to an eighth aspect of the present invention, in the vibration actuator according to the seventh aspect, there are provided two or more support portions, and each of the support portions is capable of adjusting its position independently. Actuator.

[0013]

Embodiments of the present invention will be described below in more detail with reference to the drawings. In the following description, an ultrasonic motor using an ultrasonic vibration region will be described as an example of a vibration actuator.

FIG. 1 is a view showing an embodiment of an ultrasonic motor according to the present invention. FIG. 1 (a) is a side view, and FIG.
FIG. 1B is a front view, and FIG. 1C is a side view showing a part of a support mechanism for supporting the relative motion member. FIG. 2 is a perspective view of the transducer of the ultrasonic motor shown in FIG.

First, the configuration of the vibrator 11 will be described with reference to FIG. The vibrator 11 has a fourth-order bending vibration and 1
This is a member that generates a driving force for driving the relative motion member by simultaneously performing the next longitudinal vibration. The vibrator 11 includes an elastic body 12 and two piezoelectric bodies 13a and 13b joined to the upper surface of the elastic body 12.

The elastic body 12 is a rectangular flat plate made of an elastic material such as a metal material or a plastic material. On the lower surface of the elastic body 12, at the position where the antinode of the fourth-order bending vibration is generated, the two rectangular parallelepiped driving force extracting portions 12 are provided.
a and 12b are formed in a projection shape. Also, the elastic body 1
Reference numeral 2 denotes cut-out portions 12c and 12d having a semicircular cross section at a node position of primary stretching vibration (longitudinal vibration), that is, at a central portion in the longitudinal direction. Two piezoelectric bodies 13
Reference numerals a and 13b denote electromechanical transducers composed of PZT in the present embodiment. The piezoelectric members 13a and 13b are bonded to the surface of the elastic member 12 opposite to the surface on which the driving force extracting portions 12a and 12b are formed.

As shown in FIG. 1, the vibrator 11 is disposed on the upper surface of the relative motion member 21 and is supported by support pins 29a and 29b fixed to the housing 40. The support pins 29a and 29b have their tip portions arranged in the notches 12c or 12d of the elastic body 12,
The vibrator 11 is positioned with respect to the left and right directions in the drawing and the direction perpendicular to the drawing. The housing 40
Is a part of the housing of the ultrasonic motor 1. Support pin 29
The coil springs 28a and 28b are arranged on the outer circumferences of a and 29b. The coil springs 28a and 28b are in a compressed state, and the force (downward in the drawing) is applied to the vibrator 11 so that the output take-out portions 12a and 12b of the vibrator come into press contact with the upper surface of the relative motion member 21 with a predetermined pressure. Pressure).

The relative movement member 21 is a plate-shaped member, and its lower surface is supported by a support mechanism 30 so as to be movable in the left-right direction in the drawing. Support mechanism 30
Has a configuration in which four rollers 32 are rotatably mounted on a housing 31, and the four rollers 32 are supported by contacting the lower surface of the relative motion member 21. The housing 31 is a part of the housing of the ultrasonic motor 1 like the housing 40. The housing 31 has a number of support columns 35 on the upper surface corresponding to the number of the rollers 32. The support column 35 has, at its upper end, a groove 36 provided in parallel to the direction of the amplitude of the bending vibration performed by the vibrator 11, and the groove 36 has a rotating shaft 33 of the roller 32.
Is inserted. Therefore, the roller 32 is provided in the groove 3
6 and is movable in a direction perpendicular to the lower surface of the relative motion member 21.

A spring 34 is provided in the groove 36. The spring 34 applies a force toward the relative motion member 21 to the rotating shaft 33 of the roller, so that the roller 32
Plays a role of pressing the relative motion member.
In the present embodiment, since the springs 34 are arranged in the respective groove portions 36, the four rollers 32 are elastically supported independently of each other. Therefore, even if the rollers 32 do not have to be set at a strict position, and even if there are some irregularities on the lower surface of the relative motion member 21, each of the rollers 32 can be reliably connected to the relative motion member 2 without fail.
1 is in contact with and supports the lower surface.

Next, the driving circuit of the ultrasonic motor 1 and the operation of the ultrasonic motor 1 will be described. FIG. 3 is a block diagram illustrating a drive circuit of the ultrasonic motor 1. The drive circuit 41 includes an oscillator 42 that oscillates a drive signal, and a phase shifter 43 that converts the drive signal into a signal having a phase difference of (π / 2).
And an amplifier 44 for amplifying the drive signal input to the piezoelectric body 13a and an amplifier 45 for amplifying the converted drive signal input to the piezoelectric body 13b.

The driving circuit 41 causes the piezoelectric bodies 13a, 13
An AC voltage having an electrical phase difference of 90 ° is applied to b. When applying the AC voltage to the piezoelectric bodies 13a and 13b, the elastic body 12 is connected to the GND potential. As a result of the AC voltage application, the piezoelectric bodies 13a and 13b
Vibration having a phase difference of 0 ° is performed, and a first-order longitudinal vibration and a fourth-order bending vibration are generated harmoniously in the elastic body 12. As a result of these two modes of vibration being excited in the elastic body 12, an elliptical motion, which is a combination of these vibrations, is generated on the end faces of the driving force output portions 12a and 12b. Then, the driving force extraction units 12a and 12 use this elliptical motion to make a one-dimensional (left-right direction in the drawing) contact with the relative motion member 21 that comes into pressure contact.
The relative motion of

As described above, in the present embodiment, the roller 32 is not fixed to the housing 31 and the groove 3
6 movably held. Therefore, roller 3
2, the position can be adjusted according to the position of the lower surface of the relative motion member 21, and it is not necessary to set the position strictly when assembling the ultrasonic motor as in the conventional case. Further, in the present embodiment, the roller 32 is
It is elastically supported. That is, since the roller 32 is always pushed by the spring 34 toward the relative motion member, the roller 32 is automatically arranged at a position where the lower surface of the relative motion member can be supported. Therefore, in this embodiment,
No special operation for adjusting the position of the roller 32 is required, and even if there is a variation in the thickness between the individual relative motion members, or the thickness of one relative motion member varies depending on the position. However, the roller 32 always properly supports the relative motion member.

Further, in this embodiment, each roller 32
Are elastically supported by separate and independent springs 34, respectively. Therefore, the relative motion member 2 to be supported
Even if the lower surface of the roller 1 is not flat and the support mechanism 30 uses four rollers in excess of the number required to define the plane, the distance between any one of the rollers and the relative motion member may be reduced. There is no play, and the play does not cause the performance of the ultrasonic motor 1 to deteriorate or generate noise during operation.

Further, in this embodiment, the direction in which the roller 32 can move is limited by the groove 36. Therefore, the roller 32 is dragged by the relative motion member 21 and moves in a direction parallel to the direction of the relative motion, and as a result, the relative motion member cannot be sufficiently supported.
There is no adverse effect due to the movable roller 32.

(Other Embodiments) The present invention is not limited to the above embodiment. The above embodiment is an exemplification, and has substantially the same configuration as the technical idea described in the scope of the claims of the present invention. It is included in the technical scope of the invention.

1) In the above embodiment, the case where a piezoelectric body is used as a vibration source for exciting an elastic body has been described as an example. However, this limits the types of vibration sources that can be used in the present invention. Not something. The vibration source may be any element that can apply predetermined vibration to the elastic body, and other elements that excite the elastic body by converting electric energy, magnetic energy, heat energy, or the like into mechanical displacement ( Electrostrictive element, magnetostrictive element, etc.). 2) In the above embodiment, the case where the relative motion member is supported using four rollers having a small width has been described.
It is not intended to limit the shape and number of the rollers at all, and it is also possible to arrange two or three or more wide rollers having a width approximately equal to the lateral width of the relative motion member in the longitudinal direction of the relative motion member. Good. Further, instead of the rotatable roller, a sliding member having a small coefficient of friction with the relative moving member may be arranged at the upper end of the support column 35, and the relative moving member may be slid on the sliding member. 3) In the above-described embodiment, the case where the force is caused to contact the roller with the relative motion member using the elastic force of the coil spring has been described, but this is to utilize the elastic force of another elastic member such as rubber. Alternatively, magnetic force, electrostatic force, fluid pressure, or the like may be used.

[0027]

As described above, according to the present invention,
Even if the position of the support portion of the support mechanism is not strictly set, the support portion reliably supports one surface of the relative motion member. Therefore, there is no play between the support portion and the relative motion member, and the characteristics of the vibration actuator are not degraded, and no noise is generated during the operation of the vibration actuator.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of an ultrasonic motor according to the present invention.

FIG. 2 is a perspective view of a vibrator of the ultrasonic motor shown in FIG.

FIG. 3 is a block diagram showing a drive circuit of the ultrasonic motor according to the present invention.

FIG. 4 is a diagram showing a vibration actuator using a conventional vibration actuator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultrasonic motor 11 Vibrator 21 Relative motion member 30 Support mechanism 31 Housing 32 Roller 34 Spring 35 Support pillar 36 Groove

Claims (8)

[Claims] A vibrator that excites longitudinal and bending vibrations in a flat or columnar elastic body to generate an elliptical motion in a driving force extracting portion provided at a predetermined position of the elastic body; A supporting mechanism for supporting a relative motion member disposed substantially parallel to the vibrator from a side opposite to the vibrator by a support portion, wherein the driving force take-out portion is brought into contact with the relative motion member, and A vibration actuator performing relative motion, wherein the support mechanism elastically holds the support portion. 2. The vibration actuator according to claim 1, wherein the support mechanism has a guide portion for guiding a movable direction of the support portion in a direction substantially parallel to an amplitude direction of the bending vibration. Characteristic vibration actuator. 3. The vibration actuator according to claim 1, wherein the number of the support portions is two or more, and the support mechanism elastically holds the respective support portions by mutually independent mechanisms. A vibration actuator. 4. A vibrator that excites longitudinal and bending vibrations in a flat or columnar elastic body to generate an elliptical motion in a driving force extracting portion provided at a predetermined position of the elastic body; A support mechanism for supporting a relative motion member disposed substantially parallel to the vibrator from a side opposite to the vibrator by a support portion; and applying a pressing force for bringing the driving force extracting portion into press contact with the relative motion member. A vibration mechanism that performs a relative motion with the relative motion member, wherein the support mechanism guides the support portion in a direction substantially parallel to the amplitude direction of the bending vibration, A vibrating actuator comprising: a force acting portion that causes the support portion to contact the relative motion member by applying a force in a direction repelling the pressing force to the support portion. 5. The vibration actuator according to claim 4, wherein the force acting portion is a member having a spring property. 6. The vibration actuator according to claim 4, wherein the support portion has two or more support portions, and the support mechanism has a separate force application portion corresponding to each of the support portions. A vibration actuator characterized by the above-mentioned. 7. A vibrator that excites a longitudinal vibration and a bending vibration to a flat or columnar elastic body to generate an elliptical motion in a driving force extracting portion provided at a predetermined position of the elastic body; A supporting mechanism for supporting a relative motion member disposed substantially parallel to the vibrator from a side opposite to the vibrator by a support portion, wherein the driving force take-out portion is brought into contact with the relative motion member, and In a vibration actuator that performs relative motion, the support mechanism holds the support portion so as to be position-adjustable in a direction substantially parallel to an amplitude direction of the bending vibration. 8. The vibration actuator according to claim 7, wherein there are two or more support portions, and each of the support portions can adjust its position independently.