JP2001186781A - Vibration actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration actuator that can have superior driving efficiency since applied pressure does not disturb the movement of a traveling element although the size is small, the structure is simple, and the price is low. SOLUTION: A tabular part 30a of a relative movement member 30 is held between a vibrator 10 being fixed to a base part wall 40a and a bearing 16 where urging force is given by a torsion spring 14 via a pressure arm 15 for applying pressure. Also, the relative movement member 30 is subjected to loose fitting to a guide shaft 31 where a cylinder part 30b is placed at a position other than a pressure direction, thus preventing frictional resistance from being generated by applied pressure in the guide shaft 31, and hence efficiently setting elliptical vibration generated by a vibrator 10 to linear movement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration actuator utilizing the vibration of a vibrator made of an electromechanical transducer, and more particularly to a vibration actuator having an improved method for supporting a moving element.

[0002]

2. Description of the Related Art Conventionally, this type of vibration actuator has
The moving element has been moved by using vibration generated by giving an electric signal to an electromechanical transducer such as PZT. In this mover, a vibrator is provided on the stator side, and the relative motion member is a mover, and the relative motion member is on the stator side, and the vibrator itself is a mover. Although there are differences in the shapes of these moving elements, in any case, it is necessary to pressurize at least one of the moving elements and the relative moving member from the other. Further, the moving element has a guide device so that the moving element can be moved efficiently by the driving force obtained from the vibrator, and the posture and the moving direction of the moving element are restricted. For example, JP-A-8-
In Japanese Patent No. 237971, there is provided a vibration actuator which includes two guide shafts arranged in parallel and a movable member fitted to the two guide shafts, and drives the movable member by pressing the vibrator against the movable member. It has been disclosed.

[0003]

However, the conventional vibration actuator has a problem in that since the pressing force is received by the guide device, a normal force is generated at the friction portion of the guide device by the pressing force, and the frictional resistance is increased. Was. For example, in the vibration actuator disclosed in Japanese Patent Application Laid-Open No. H8-237971, the force applied to the vibrator in any direction acts on the guide shaft to increase the frictional resistance. . As a result, it was not possible to efficiently convert the vibration energy of the vibrator into a moving motion. on the other hand,
In some cases, the frictional force has been reduced by, for example, arranging a linear guide or a rolling bearing at a position where the moving element receives a pressing force. These methods work effectively in terms of lowering frictional resistance, but the linear guide requires high accuracy, and also requires a large number of rolling bearings to be arranged. There was a problem. Further, in both cases, it is necessary to dispose the vibration actuator over the entire movement range, and there is a problem that the vibration actuator cannot be downsized.

SUMMARY OF THE INVENTION An object of the present invention is to provide a vibration actuator which has a small and simple structure, is inexpensive, and has a high driving efficiency because a pressing force does not hinder the movement of a moving element.

[0005]

The present invention solves the above-mentioned problems by the following means. In addition, in order to make it easy to understand, description is given with reference numerals corresponding to the embodiment of the present invention, but the present invention is not limited to this. That is, the invention according to claim 1 provides a vibrator (10) composed of an electromechanical transducer, a relative motion member (30) that moves relatively to the vibrator, and a device between the vibrator and the relative motion member. A pressure unit (14, 15) for applying a pressing force to the pressure unit, and a guide shaft (31) arranged in a direction other than the pressure direction of the pressure unit and guiding the relative motion member to be movable in the axial direction. Actuator.

According to a second aspect of the present invention, there is provided a vibrator (10) comprising an electromechanical transducer, a relative motion member (32) moving relatively to the vibrator, and a vibrator and the relative motion member. Pressurizing units (14, 15) for applying a pressing force between them,
A movable table (33) provided with the vibrator and the pressurizing unit and moving relative to the relative motion member, and a movable table (33) arranged in a direction other than the pressing direction of the pressurizing unit and capable of axially moving the movable table And a guide shaft (31) for guiding the vibration.

[0007] The third aspect of the present invention is the first or second aspect.
In the vibration actuator described in (1), the pressing unit (1)
The vibrating actuator is characterized in that the pressing direction of (4, 15) passes through the pressing position and coincides with the tangential direction at the pressing position of a virtual circle centered on the guide shaft (31).

[0008] The invention of claim 4 is the first to third aspects of the present invention.
In the vibration actuator according to any one of the above, the relative movement member (3) of the pressing portion (14, 15)
0, 32), the vibration actuator having a low friction portion (16) for reducing frictional resistance with the relative motion member.

[0009] The invention of claim 5 is the invention of claims 1 to 4.
In the vibration actuator according to any one of the above, the low friction portion (16) is disposed on the opposite side of the vibrator and the relative motion member in a pressing direction of the pressing portion. A vibration actuator characterized by the following.

The invention of claim 6 is the invention of claims 1 to 5
The vibration actuator according to any one of the preceding claims, wherein the low friction portion (16) is a rotatable rolling member or a sliding member having a small friction coefficient of the material itself.

[0011] The invention of claim 7 is the invention of claims 1 to 6.
The vibration actuator according to any one of the above, wherein the relative motion member (30, 32) or the moving table (33) is movable by a predetermined amount in a pressing direction of the pressing unit. Vibration actuator.

The invention according to claim 8 is the invention according to claims 1 to 6.
The vibration actuator according to any one of the above, wherein the relative movement member (30, 32) or the movable table (33) is rotatable by a predetermined amount around the guide shaft (31). It is a vibration actuator.

[0013]

Embodiments of the present invention will be described below in more detail with reference to the drawings. (First Embodiment) FIG. 1 is an overall view of a first embodiment of a vibration actuator according to the present invention. The vibration actuator 1 includes a vibrator 10, a relative motion member 30, a guide shaft 3
1, a torsion spring 14, a pressure arm 15, a bearing 16, a base 40, and the like.

The vibration actuator 1 is a vibration actuator using a radially symmetric elongation vibration mode and a non-axially symmetric in-plane vibration mode. FIG. 2 shows the vibration actuator 1
FIG. 4 is a diagram for explaining a driving principle based on vibration of a vibrator 10. The vibrator 10 includes a piezoelectric element 11, an electrode 12, a sliding member (not shown), and the like. The piezoelectric element 11
For example, a piezoelectric material such as PZT is formed into a donut plate shape, and the entire surface is polarized in the plate thickness direction. This donut plate shape is designed and manufactured such that the resonance frequencies of the radially symmetric elongation vibration mode (R, 1) and the non-axisymmetric in-plane vibration mode ((1, 1)) are substantially equal.

The piezoelectric element 11 has fan-shaped first and second electrodes 12a and 12b formed on the surface thereof [FIG.
(A)], a third electrode 12c is formed on almost the entire back surface [FIG. 2 (B)].

A first AC voltage is applied to the first electrode 12a of the vibrator 10 by a driving voltage generator including an oscillator, a phase shifter, an amplifier and the like. Also, the second electrode 1
2b has an electrical phase (π /
A second AC voltage that differs by 2) is applied. The third electrode 12c on the back surface is connected to the GND potential.

The vibrator 10 has a frequency of AC voltage of 2
By approaching the resonance frequency of the two vibration modes,
Resonating in two modes, radially symmetric elongational vibration and non-axisymmetric in-plane vibration occur simultaneously.

The radially symmetric elongational vibration (R, 1) is shown in FIG.
As shown in (C), the vibration is a symmetrical expansion / contraction vibration in the radial direction (radial direction) with node A as a node, and has radial components Ur at points C1 and C2. In addition, non-axisymmetric in-plane vibration ((1,
1)), as shown in FIG. 2 (D), using the points B1 and B2 as nodes, as shown by a broken line, a deformation such as crushing (shattering) in the same plane is performed by changing the left and right directions in FIG. 2 (D). , And has a displacement component Uθ in the direction of the arrow at points C1 and C2 on the circumference. Then, the vibrator 10 includes C1, C2
An elliptical motion as shown in FIG. 2A is generated as a displacement obtained by combining two vibrations at a position of a point (a driving force extracting portion). At this time, a frictional force is generated between the sliding member 13 provided on the vibrator 10 and the relative moving member 30 in the moving direction of the relative moving member 30 to obtain the linear driving force of the relative moving member 30. Can be.

FIG. 3 is a cross-sectional view of the vibration actuator 1 according to the first embodiment taken along a plane parallel to the vibration plane immediately before the vibrator 10. FIG. 4 is a side view of the vibration actuator 1 excluding the torsion spring 14 and the support 40b in the foreground. Hereinafter, the configuration of the vibration actuator 1 will be described with reference to FIGS. In the first embodiment, the moving element is the relative movement member 30,
The vibrator 10 is a stator. The vibrator 10 is fixed by inserting the support portion 21 fixed to the base portion wall 40a into the center hole.

The relative motion member 30 functions as a moving element while the vibrator 10 serves as a stator. The relative movement member 30 has a plate-like portion 30 having a length equal to or longer than the movement stroke.
a and a cylindrical portion 30b, and the cylindrical portion 30b has a round hole corresponding to the guide shaft 31.
On the other hand, by performing the gap fitting so that the fitting accuracy and the fitting length are sufficient for positioning the relative motion member 30, the direction in which the linear movement is possible becomes the driving direction of the elliptical motion generated by the vibrator 10. Is regulated as follows. The relative motion member 30 is sandwiched between a sliding member 13 of the vibrator 10 and a bearing 16 described later, and the bearing 16 presses the relative motion member 30 against the sliding member 13.

The guide shaft 31 is a round bar having a smooth surface that guides the movement of the relative motion member 30 by fitting into the round hole of the relative motion member 30 with a clearance.
0b is fixed to the base portion 40.

The torsion spring 14 is provided with a shaft 15 a of the pressing arm 15.
, A torsion spring wound around the center, one end of which is fixed to the base 40 and the other end of which is hung on the pressing arm 15. The torsion spring 14 is applied to the pressing arm 15 in a charged state by a predetermined amount, and applies an urging force to the pressing arm 15 to generate a predetermined pressing force amount in the bearing 16.

The pressing arm 15 is attached to the base wall 40a so as to be rotatable smoothly about the shaft 15a. The urging force of the torsion spring 14 causes a moment about the shaft 15a (see FIG. 3). , Arrow M), and a predetermined pressure is generated in the bearing 16. here,
The pressing direction of the pressing force at the position where the bearing 16 presses the relative motion member is such that the guide shaft 31 is the center of rotation.
It points in the tangential direction of the virtual circle passing through the pressing position.

The bearing 16 presses the relative motion member 30 against the vibrator 10 by the pressurizing force from the pressurizing arm 15 (arrow F in FIG. 3), and also controls the relative motion member 30 by the normal force exerted by the pressurizing force. Is a low-friction member for reducing the friction loss. Since the bearing 16 is a rolling bearing, the friction loss is very small.

The base portion 40 is a base serving as a base of the vibration actuator 1, and has a base portion wall 40a and two columns 40b. The support portion 21 and the shaft 15a are vertically fixed to the base portion wall 40a.
, A guide shaft 31 is fixed.

The position of the relative motion member 30 is regulated by the guide shaft 31 in four degrees of freedom other than the axial direction of the guide shaft 31 and around the axis of the guide shaft 31 out of the six degrees of freedom. Is determined by the frictional force between the sliding member 13 provided on the vibrator 10 and the relative motion member 30.

The degree of freedom around the guide shaft 31 is determined by the bearing 16 pressing the relative motion member 30 against the vibrator 10. Therefore, the vibrator 10 does not need to be mounted movably in the pressing direction, and is fixed to the base portion wall 40a, so that the positioning of the relative motion member 30 can be performed with high accuracy.

Further, since the pressing force between the vibrator 10 and the relative motion member 30 acts only between the vibrator 10 and the bearing 16, this pressing force does not affect the guide shaft 31. . Therefore, the relative motion member 3 is
No frictional force is generated between 0 and the guide shaft 31.

Further, since the bearing 16 is provided at a portion where the pressing force acts, the movement of the relative motion member 30 is not hindered by the action of the pressing force. Therefore,
The pressing force is applied to the vibrator 10 required for driving and the relative motion member 30.
In addition to generating a frictional force therebetween, unnecessary frictional resistance that hinders movement of the relative motion member 30 is not generated.

According to this embodiment, since the positioning accuracy of the relative motion member 30 is high and unnecessary frictional resistance due to the pressing force is small, an efficient and compact vibration actuator 1 can be manufactured at low cost.

(Second Embodiment) FIG. 5 is a side view showing a second embodiment of the present invention. In the vibration actuator 1 according to the first embodiment, an example is described in which the vibrator 10 is a stator and the relative motion member 30 is a mover. However, in the second embodiment, these relationships are reversed. That is, in the vibration actuator 2 according to the second embodiment, the vibrator 10 is a moving element, and the relative motion member 32 is a stator. In the description of the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the repeated description will be omitted as appropriate. The vibration actuator 2 includes a vibrator 10, a relative motion member 32, a moving table 33, a guide shaft 31, and a pressing arm 15.
-2, a biasing member (not shown) and the like in addition to the bearing 16, the base 40, and the like.

The vibrator 10 is fixed to the moving table 33 via the support 21 and is a main part of the moving element that moves integrally with the moving table 33.

The relative movement member 32 is a plate fixed to the base portion wall 40a, and is disposed over the entire driving range.

The moving table 33 includes the vibrator 10 and the pressing arm 15.
-2, a base of a moving member that moves in the driving direction of the vibration actuator 2 with the bearing 16 and the like integrally attached, and has a main body portion 33a and a cylindrical portion 33b. The vibrator 10 is fixed to the main body portion 33a via the support portion 21, and the bearing 16 and a biasing member (not shown) are fixed via the pressing arm 15-2. The cylindrical portion 33 b has a round hole corresponding to the guide shaft 31, and this round hole has a clearance fit with the guide shaft 31 with sufficient fitting precision and fitting length for positioning of the movable table 33. Thus, the direction in which the linear movement is possible is restricted so as to be the driving direction of the elliptical motion generated by the vibrator 10.

The pressing arm 15-2 has a rotation center at the main body 33.
a, which presses the bearing 16 against the relative movement member 32 by an urging member (not shown).
The biasing member has a fixed end fixed to the main body 33a,
The moving end is a torsion spring hung on the pressing arm 15-2.

The bearing 16 is a low friction member which presses the relative motion member 32 with the vibrator 10 so as to sandwich the relative motion member 32 and reduces a friction loss with the relative motion member 32 due to a normal force exerted by the pressing force. is there.

Since the pressing force acts only between the bearing 16 and the vibrator 10 on both sides of the relative motion member 32, it does not affect the guide shaft 31 at all. Therefore,
The movable table 33 can efficiently convert the elliptical motion generated by the vibrator 10 into a linear motion without causing a loss such as frictional resistance due to the pressing force.

According to the present embodiment, since the unnecessary frictional resistance due to the pressing force is small, the vibration actuator 2 in which the efficient small-sized vibrator 10 moves can be manufactured at low cost.

(Modifications) Various modifications and changes are possible without being limited to the embodiment described above, and they are also within the equivalent scope of the present invention.

(1) In each of the embodiments, an example in which a bearing is used as a low friction member has been described. However, the present invention is not limited to this. A sliding member that reduces frictional resistance due to pressure, such as semi-contact vibration friction using vibration of a vibrator other than the vibrator, may be used.

(2) In each embodiment, the cylindrical portion 30b
And 33b show an example of a continuous pipe,
However, the present invention is not limited to this. For example, the cylindrical portion may be provided only at both ends, or a plurality of cylindrical portions may be provided.

(3) In each of the embodiments, an example has been described in which an annular vibrator utilizing in-plane vibration is used as the vibrator. However, the present invention is not limited to this. For example, a longitudinal vibration primary mode and a bending vibration A vibrator that drives by generating the fourth mode may be used, or a vibrator that generates the primary longitudinal vibration mode and the secondary torsional vibration mode may be used.

[0043]

As described above in detail, according to the first aspect of the present invention, since the guide shaft is provided in a direction other than the pressing direction of the pressing portion, no pressing force acts on the guide shaft, and the loss due to frictional resistance occurs. Can be reduced.

According to the second aspect of the present invention, there is provided a moving table,
Since the guide shaft is provided in a direction other than the pressing direction of the pressing unit, even if the vibrator itself moves, the pressing force does not act on the guide shaft, and the loss due to frictional resistance can be reduced.

According to the third aspect of the present invention, since the pressing direction of the pressing portion coincides with the tangential direction of the imaginary circle centered on the guide shaft, the pressing force does not act on the guide shaft at all. As a result, the frictional resistance caused by the friction does not occur on the guide shaft, and efficient driving can be performed.

According to the fourth aspect of the invention, since the low friction portion is provided at the contact portion of the pressing portion with the relative motion member, the frictional resistance due to the pressing force can be reduced, and the driving efficiency of the relative motion member can be reduced. And drive can be made smoother.

According to the fifth aspect of the present invention, since the low friction portion is located on the opposite side of the vibrator and the relative motion member, only one low friction portion is required, and the vibration actuator is small and inexpensive. be able to.

According to the sixth aspect of the present invention, since the low friction portion is a rolling member or a sliding member, the structure is simplified.
The reliability of the vibration actuator is increased, and the price can be reduced.

According to the seventh aspect of the present invention, since the relative movement member or the movable table can be moved in the pressing direction by a predetermined amount, a constant pressing force can be always obtained, and stable driving can be performed. it can.

According to the eighth aspect of the present invention, since the relative motion member or the moving table can rotate by a predetermined amount around the guide axis, a constant pressing force can always be obtained with a simple configuration.
Stable driving can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a driving principle based on vibration of a vibrator.

FIG. 3 is a cross-sectional view of the vibration actuator 1 cut in a plane parallel to a vibration plane immediately before a vibrator 10;

FIG. 4 is a side view of the vibration actuator 1.

FIG. 5 is a side view showing a second embodiment of the present invention.

[Explanation of symbols]

 1, 2 Vibration actuator 10 Vibrator 11 Piezoelectric element 13 Sliding material 14 Torsion spring 15, 15-2 Pressing arm 16 Bearing 30, 32 Relative motion member 33 Moving table 40 Base

Claims (8)

[Claims] A vibrator made of an electromechanical transducer, a relative motion member that moves relatively to the vibrator, a pressurizing section that applies a pressing force between the vibrator and the relative motion member, A guide shaft that is arranged in a direction other than the pressing direction of the pressing unit and guides the relative motion member so as to be movable in the axial direction. 2. A vibrator made of an electromechanical transducer, a relative motion member that moves relatively to the vibrator, a pressurizing unit that applies a pressing force between the vibrator and the relative motion member, A moving table provided with the vibrator and the pressurizing unit, the moving table moving with respect to the relative motion member; and a moving table arranged in a direction other than a pressing direction of the pressurizing unit, and guiding the moving table in an axial direction. A vibration actuator comprising: a guide shaft; 3. The vibration actuator according to claim 1, wherein a pressing direction of the pressing unit is a tangent at a pressing position of a virtual circle passing through the pressing position and centering on the guide shaft. A vibration actuator, wherein the vibration actuator is aligned with a direction. 4. One of claims 1 to 3
The vibration actuator according to any one of claims 1 to 3, further comprising: a low friction portion at a contact portion of the pressing portion with the relative motion member, the friction portion reducing a frictional resistance with the relative motion member. 5. The method according to claim 1, wherein:
The vibration actuator according to any one of claims 1 to 3, wherein the low-friction portion is disposed on an opposite side of the vibrator and the relative motion member in a pressing direction of the pressing portion. 6. Any one of claims 1 to 5
The vibration actuator according to claim 1, wherein the low friction portion is a rotatable rolling member or a sliding member having a small friction coefficient of the material itself. 7. One of claims 1 to 6
The vibration actuator according to any one of claims 1 to 3, wherein the relative movement member or the movable table is movable in a pressing direction of the pressing unit by a predetermined amount. 8. Any one of claims 1 to 6
The vibration actuator according to claim 1, wherein the relative movement member or the movable table is rotatable by a predetermined amount around the guide axis.