JPH11136971A - Oscillation actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid seizure surely. SOLUTION: A face 22 coming into contact with the pressure contact parts 13a, 13b at driving power take-out sections 11a, 11b only when oscillation of an oscillator 10A stops is provided contiguously to the motion area 21 of the oscillator in a relative motion member 20 on same plane as the motion area 21. Consequently, the oscillator 10A passes through the motion area 21 of the oscillator in the relative motion member 20 (in case of self-advancing) or drives the oscillator (in case of fixed oscillator) when the oscillator 10A is driven and the pressure contact parts 13a, 13b at the driving power take-out sections 11a, 11b come into pressure contact with the face 22 disposed contiguously to the motion area of the relative motion member 20 on same plane as the motion area when the oscillator 10A is stopped. Since abrasion powder scarcely adhere to the contacting face 22, seizure can be avoided surely upon stoppage of the oscillator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration actuator, and more particularly, to a vibration actuator having a vibrator and a relative motion member which makes pressure contact with the vibrator and performs relative motion with respect to the vibrator.

[0002]

2. Description of the Related Art Conventionally, an elastic body is vibrated by an electro-mechanical conversion element such as a piezoelectric element, and a plurality of vibrations are applied to the elastic body.
For example, there is known a vertical-bending type vibration actuator that generates a longitudinal vibration and a bending vibration in harmony and generates an elliptical motion in a driving force extracting portion provided in a part of an elastic body.
Such a vibration actuator has characteristics such as good controllability, high holding force, and quietness, and is roughly classified into a rotary type and a linear type. Rotary vibration actuators
It is used for AF motors of cameras. As a linear vibration actuator, for example, Japanese Patent Application Laid-Open
What is disclosed in -143771 publication etc. is known.

In the vertical-bending type linear vibration actuator disclosed in the above-mentioned publication, a protruding driving force take-out portion is provided at a portion of the antinode of bending vibration generated by the vibrator.
The tip of the driving force extracting portion is periodically displaced in an elliptical shape. For this reason, the driving force has been extracted by the leading end of the driving force extracting portion coming into pressure contact with the relative motion member. In other words, when the relative moving member is fixed, the vibrator runs on the relative moving member serving as a track, and conversely, when the vibrator is fixed, the relative moving member serving as an object to be driven is moved. Driven.

[0004]

In many cases, in the above-described vertical-bending type vibration actuator, a friction material or the like is bonded to the contact surface of the driving force extracting portion with the relative motion member by bonding or the like. A device has been devised to reduce the resistance generated when sliding between the moving member and the moving member.

However, when the vibration actuator is driven for a long time, stopped and left, and then driven again, the friction material and the relative motion member are firmly joined to each other, resulting in an inability to re-drive, that is, inconvenience of sticking. was there.

This is based on the following reasons. Generally, the material of the relative motion member is a metal such as stainless steel, and engineering plastic is used as the friction material. Therefore, when the vibration actuator is driven for a long time, the contact surface between the friction material and the relative motion member is slid. Wear powder and the like accumulate and adhere. Due to its structure (by nature), the vibration actuator keeps applying pressure even when stopped.
The vibrator is in pressure contact with the relative motion member via the wear powder. Since the abrasion powder plays a role like an adhesive, the above-mentioned sticking occurs when stopping and leaving the apparatus and then driving it again.

The present invention has been made in view of the disadvantages of the related art, and an object of the present invention is to provide a vibration actuator capable of almost surely preventing the occurrence of sticking.

[0008]

According to a first aspect of the present invention, there is provided a vibration actuator, comprising: a vibrator (10A) for generating a plurality of vibrations in harmony; and a driving force output portion (11a, 11b) for the vibrator. ) In pressure contact with at least a portion of
A relative movement member (20) that moves relative to the vibrator;
And the motion area (21) of the vibrator of the relative motion member
And the pressing contact portions (13a, 1a, 1b, 1c) of the driving force take-out portion only when the vibrator stops vibration.
3b) and a contact surface (22) at the time of stop for contacting the contact surface 3b).

According to this, when the vibrator is driven, it passes through the motion area of the vibrator of the relative motion member (in the case of a self-propelled type) or drives (when the vibrator is fixed), and when stopped, the relative motion member. The pressing contact portion of the driving force take-out portion comes into pressure contact with the stop contact surface arranged on the same surface adjacent to the above-mentioned motion region. Since there is almost no adhesion or accumulation of wear powder on the contact surface at the time of stop, it is possible to almost certainly avoid the occurrence of sticking when the vibrator stops.

In this case, the stop contact surface (22)
Is the motion area (21) of the oscillator of the relative motion member (20)
If they are arranged on the same plane adjacent to each other, the relative motion member (2
The contact surface at the time of stop (22) is formed on a part of the relative movement member (20), as a matter of course. Well,
Alternatively, as in the invention described in claim 3, the stop-time contact surface (22) may be formed on at least one end of the relative movement member in the relative movement direction or a direction orthogonal thereto.

Further, in each of the inventions according to the first to third aspects, the stop contact surface (22) is provided in the movement area (2).
Although it may be a surface having the same surface roughness of the same material as 1), for example, as in the invention according to claim 4,
The stop contact surface (22) may have a different surface roughness from the movement area (21). In this case, it is preferable that the surface roughness of the contact surface at the time of stop is rougher than that of the motion region and the contact area with the vibrator is smaller. Such a contact surface at the time of stopping having a rough surface roughness can be formed, for example, by grinding. Alternatively, as in the invention as set forth in claim 5, the stop-time contact surface (22) has a coefficient of friction between the vibrator and the pressure contact portions (13a, 13b) that is equal to the motion region (21). And may be different. In this case, it is desirable that the coefficient of friction between the stop contact surface and the pressure contact portion of the vibrator is smaller than the motion region. Or,
The stop-time contact surface may be formed of a material different from the motion area.

In each of the first to sixth aspects of the present invention, as in the seventh aspect of the present invention, the stop contact surface (22) is formed by a film formed on a predetermined base material surface. It may be formed. In this case, the coating can be formed by various coating processes such as plating (plating), thermal spraying, vapor deposition, and coating. However, in the case of plating, a so-called satin finish is desirable.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

<< First Embodiment >> Hereinafter, a first embodiment of the present invention will be described with reference to FIG.

FIG. 1A is a plan view of a vibration actuator 100 according to the first embodiment, and FIG.
FIG. 1 schematically shows a front view of the vibration actuator 100. In the present embodiment, the vibration actuator 100
As an example, an ultrasonic actuator using an ultrasonic vibration region is used.

The vibration actuator 100 generates a plurality of vibrations, specifically, vibrations in a longitudinal vibration mode (here, L1 mode) and a bending vibration mode (here, B4 mode) in harmony. Is an ultrasonic actuator that extracts a driving force from the position. The vibration actuator 100 includes the vibrator 10A and the relative motion member 2.
0.

As shown in FIGS. 1A and 1B, the vibrator 10A is fixed to an elastic body 11 near a longitudinal center of one surface of the elastic body 32 via a predetermined clearance. It includes a pair of piezoelectric bodies 12a and 12b, which are (joined) electro-mechanical conversion elements, and another pair of piezoelectric bodies 12c and 12d arranged on both sides of these piezoelectric bodies.

The elastic body 11 is of a rectangular flat plate having a predetermined thickness and designed so that the resonance frequencies of the first-order longitudinal vibration and the fourth-order bending vibration have very close values.

The piezoelectric bodies 12a and 12b are driving piezoelectric bodies, and generate longitudinal vibration and bending vibration in the elastic body 11 by the piezoelectric effect (second-order mode effect). The piezoelectric bodies 12c and 12d are monitoring piezoelectric bodies for monitoring the state of vibration generated in the elastic body 11, and the outputs thereof are connected to a control circuit (not shown). Further, an electrode 14 serving as a GND line is adhered to the elastic body 11 on the other surface (drive surface) side of the central portion in the longitudinal direction. The electrode (common electrode) 14 is formed by, for example, soldering a lead wire to the elastic body 11 or bonding a metal foil with a lead wire to the elastic body 11.

In the vibrator 10A, a first AC voltage having a frequency close to the resonance frequency is applied to the piezoelectric body 12a, and the piezoelectric body 12b has the same frequency as the first AC voltage and an electrical voltage. A second AC voltage having a phase difference of 90 degrees is applied. Thereby, the first-order longitudinal vibration and the fourth-order bending vibration are harmoniously generated in the elastic body 11.

4 generated on the other surface of the elastic body 11
The driving force take-out portion 11 is located at the antinode of the next bending vibration.
a and 11b are integrally formed of the same material as the elastic body 11 (or separately formed of the same or different material). Then, the driving force is generated by the distal ends of the driving force extracting portions 11a and 11b performing elliptical motion (elliptical periodic displacement). In this case, the vibrator 10A is pressed against the relative motion member 20 by the pressing force of a pressing mechanism (not shown), and the distal ends of the driving force extracting portions 11a and 11b are
It is in pressure contact with the relative motion member 40. This allows
The vibrator 10A self-runs on the relative movement member 20 which is a linear trajectory in the right or left direction on the paper of FIG. 1, or when the vibrator 10A is fixed, the relative movement member 20 Driven to the left.

At the tips of the driving force extracting portions 11a and 11b,
For example, friction materials 13a and 13b made of engineering plastic such as polyflon (manufactured by Daikin Industries, Ltd.) and Vespel (manufactured by DuPont) are attached.
These friction materials 13a and 13b constitute a pressure contact portion.

In the present embodiment, the relative motion member 20 includes a driving frictional contact portion 21 as a motion region of the vibrator 10A and a stop portion formed at one end (the left end in FIG. 1A). And a stop contact portion 22 as a contact surface. In the present embodiment, a stainless steel member is used as the relative movement member 20, and the frictional contact portion 21 at the time of driving has the surface of the stainless steel exposed. In addition, the stop-time contact portion 22 is formed of a sprayed film (coating) of alumina ceramics, which is a kind of porous ceramics, on the surface of stainless steel as a base material.

The stop-time contact portion 22 may be of the same exposed stainless steel surface as the drive-time friction contact portion 21. However, the stop-time contact portion 22 may be made of abrasive paper so as not to form a step with the drive-time friction contact portion 21. Alternatively, it may be formed by attaching papers such as emery paper. Alternatively, the friction material 13
It may be formed by grinding and finishing so as to reduce the contact area with a and 13b. Alternatively, it may be formed by a coating formed on the stainless steel surface by plating, spraying, coating or the like.

According to the vibration actuator 100 according to the first embodiment described above, when the vibrator 10A is driven, the friction members 13a and 13b affixed to the tips of the driving force output portions 11a and 11b relatively move. A linear relative motion is performed within the range of the friction contact portion 21 at the time of driving while being brought into contact with the moving member 20 under pressure.
3a and 13b are stopped in a state where they are in contact with the contact portion 22 at the time of stop where there is almost no adhesion and accumulation of wear powder. Thus, in the present embodiment, the vibrator 10A can travel or drive the driving friction contact portion 21 during normal vibration, and there is no hindrance to traveling or driving. On the other hand, while the vibration is stopped,
By contacting the stop contact portion 22 where there is almost no accumulation, it is possible to avoid a trouble that the sticking occurs and the vehicle cannot run again or restart.

The vibration actuator 100 of the present embodiment
May be a type in which the vibrator 10A is self-propelled or a type in which the relative motion member 20 is driven by the vibrator 10A.
Considering the movement from 1 to the stop contact portion 22, it can be said that application to the type in which the vibrator 10A is self-propelled is easier.

In the first embodiment, the case where the stop-time contact portion 22 is set to only one end of the frictional contact surface of the relative motion member 20 with the vibrator 10A has been described. As shown in ()), the stop-time contact portions 22 may be arranged at both ends in the relative motion direction of the driving friction contact portions 21 of the relative motion member 20.

The first embodiment and FIG. 2 (A)
In the modification of the first embodiment, the stop-time contact portion 22 is set so as to cover the entire width of the friction contact surface of the relative motion member 20 in the width direction. However, the present invention is not limited to this, and as shown in FIGS. 2B and 2C, the stop-time contact portion 22 is formed only in the width portion corresponding to the width of the friction members 13a and 13b constituting the pressure contact portion. It may be formed.

Further, as shown in FIGS. 2 (D) and 2 (E), the width of the frictional contact surface of the relative motion member 20 in the short side direction is enlarged, and a stop is made at a part of the short side direction. The time contact portion 22 may be arranged. These FIGS. 2 (D) and 2
The relative motion member 20 shown in (E) is particularly suitable for a type in which the vibrator 10A is fixed and the relative motion member 20 is driven by the vibrator 20A. In these cases,
When the vibration of the vibrator 10A is stopped, the relative motion member 20 is driven by a drive system (not shown) in a direction (short side direction) orthogonal to the longitudinal direction, and the stationary contact member 2 of the relative motion member 20 is stopped.
At 2 the vibrator 10A stops.

The first embodiment and FIG.
In the modified examples shown in (A) to (E), the case where the stop contact portion 22 is provided in a part of the relative motion member 20 has been described, but the present invention is not limited to this, The contact portion may be constituted by a surface of another member different from the relative motion member, and may be arranged in contact with the relative motion member or via a predetermined clearance. In short, it is sufficient that the stop-time contact portion is arranged on the same plane adjacent to the motion area of the vibrator 10A. However, when the stop contact portion is constituted by a surface of a member different from the relative motion member, and when a predetermined clearance is provided between the relative motion member and the stop, the clearance can be easily passed by the vibrator 10A. It is desirable that the size be about the same (for example, about 1 μm).

<< Second Embodiment >> Next, a second embodiment of the present invention will be described with reference to FIG. Here, for the same or equivalent components as those in the first embodiment described above,
The same reference numerals are given and the description is omitted.

FIG. 3A is a plan view of the vibration actuator 110 according to the second embodiment, and FIG.
2 schematically shows a front view of the vibration actuator 110. The vibration actuator 110 is configured so that the vibrator 10A does not run on its own, but drives the roller-shaped relative motion member 30 to rotate.

The relative movement member 30 according to the second embodiment
In this case, half of the circumferential surface of the roller-shaped relative motion member 30 in the axial direction is a driving friction contact portion 21, and the other half is a stop contact portion 22.

According to the vibration actuator 110,
When the vibrator 10A is driven (during vibration), the friction material 13a,
13b is in contact with the friction contact portion 21 at the time of driving,
When the vibrator 10A stops, the relative motion member 30 is moved in the axial direction by a drive system (not shown),
It comes into contact with.

According to the second embodiment described above,
The vibrator 10A has a driving frictional contact portion 2 during normal vibration.
1 can be driven, and there is no problem in driving. On the other hand, during the stop of the vibration, the contact part 2 at the time of stop where there is almost no adhesion and accumulation of wear powder
By contacting the contact 2, it is possible to avoid a trouble in which the actuator cannot be driven again due to sticking.

In the above-described second embodiment, the stop contact portion 22 is set on the entire axial half of the peripheral surface of the relative motion member. However, the present invention is not limited to this, and is shown in FIG. As described above, the stop-time contact portion 22 may be formed only in the width portion corresponding to the width of the friction members 13a and 13b constituting the pressure contact portion.

Further, the second embodiment and FIG.
In the modification of the first embodiment, the stop-time contact portion 22 is set only on one end in the axial direction of the frictional contact surface of the vibrator 10A of the relative motion member 30. However, for example, as shown in FIG. The stop-time contact portions 22 may be arranged at both axial ends of the drive-time friction contact portions 21.

Further, the relative motion member 30 is not limited to a roller shape, and may have any shape.

In the first and second embodiments, the case where the present invention is applied to the ultrasonic actuator using the ultrasonic vibration range has been described. However, the present invention is not limited to this. However, it is needless to say that the present invention can be applied to a vibration actuator using another vibration region.

In the first and second embodiments, L
The vibration actuator using the 1-B4 type composite vibration has been described. However, the present invention is not limited to this, and L1-B2, L1-
The present invention can be similarly applied to a vibration actuator using a combination of a plurality of other vibration modes as well as a vibration actuator using another deformed degenerate / longitudinal-bending mode such as B8.

In the above embodiment, the case where the piezoelectric body is used as the electromechanical conversion element has been described.
The invention is not limited thereto, and an electrostrictive body or a magnetostrictive body can be used.

Further, in the above embodiment, the case where the driving force take-out portions 11a and 11b of the elastic body 11 are protruded from the elastic body 11 (projection-like) has been described. Also, since the antinode of the bending vibration generated at the time of driving (the part having the largest amplitude) functions as the driving force extracting portion, in this case, it is sufficient if the antinode of the bending vibration is in pressure contact with the relative motion member. .

[0042]

As described above, according to the first to seventh aspects of the present invention, there is an unprecedented excellent effect that occurrence of sticking can be almost certainly avoided.

In particular, when the surface roughness of the contact surface at the time of stop is made different from the movement area as in the invention of claim 4, the contact area of the contact surface at the time of stop with respect to the vibrator is reduced. In addition, the appearance of sticking can be strongly prevented.

In particular, when the stop-time contact surface is formed of a material different from the movement area as in the invention according to claim 6, the stop-time contact surface is made different from the movement area and the material. In addition, even if the material is not suitable for driving the vibrator, it is possible to use a material that prevents the occurrence of sticking.

[Brief description of the drawings]

FIG. 1A is a plan view of a vibration actuator according to a first embodiment, and FIG. 1B is a front view of the vibration actuator.

FIG. 2 is a view showing a modified form of the relative motion member according to the first embodiment ((A) to (E)).

FIG. 3A is a plan view of a vibration actuator according to a second embodiment, and FIG. 3B is a front view of the vibration actuator.

FIG. 4 is a view showing a modification of the relative motion member according to the second embodiment ((A), (B)).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10A Vibrator 11a, 11B Driving force take-out part 13a, 13b Friction material (pressure contact part) 20 Relative motion member 21 Friction contact part at drive (motion area) 22 Contact part at stop (contact surface at stop) 100 Vibration actuator

Claims (7)

[Claims] A vibrator that generates a plurality of vibrations harmoniously; a relative motion member that presses and contacts at least a part of a driving force extracting portion of the vibrator to relatively move with respect to the vibrator; A stop contact surface that is arranged on the same plane adjacent to the motion area of the vibrator of the relative motion member and that contacts the pressurized contact portion of the driving force takeout unit only when the vibrator stops vibrating; A vibration actuator comprising: 2. The vibration actuator according to claim 1, wherein the stop contact surface is formed in a part of the relative motion member. 3. The vibration according to claim 1, wherein the stop-time contact surface is formed on at least one end of the relative movement member in the relative movement direction or a direction orthogonal to the relative movement direction. Actuator. 4. The vibration actuator according to claim 1, wherein a surface roughness of the stop contact surface is different from a surface roughness of the movement area. 5. The stop-time contact surface according to claim 1, wherein a coefficient of friction between the stop contact surface and the pressure contact portion of the vibrator is different from that of the motion region. A vibration actuator as described. 6. The vibration actuator according to claim 1, wherein the stop-time contact surface is formed of a material different from that of the movement area. 7. The vibration actuator according to claim 1, wherein the stop-time contact surface is formed by a film formed on a predetermined base material surface.