JP2001224186A - Vibration actuator and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration actuator, having a fixing support structure which enables fixing support by positioning a vibrator having small gutter and high accuracy without restraining vibration, and can be assembled readily. SOLUTION: This vibration actuator uses a vibrator 10, which generates simultaneously an expanding vibration mode which is symmetric in the radial direction and expands and contracts in the radiation direction and an in-plane vibration mode, which is not axially symmetric and bends axially asymmerically in the same plane. The vibrator 10 is provided with a piezoelectric element 11 and sliding material 13, and generates vibration which drives a relative movement member 30. For fixing the vibrator 10 to a base 20, coming-off is prevented by using a part 22c preventing coming-off which is formed by thermal deformation at the tip of a position regulating part installed on the base 20. The section form of the position regulating part is elliptical and rotation of the vibrator 10 is stopped.

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 vibration of a vibrator in an in-plane direction, and more particularly to a vibration actuator having an improved method of holding a vibrator and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, this type of vibration actuator has
Donut plate-shaped vibration that simultaneously generates a radially symmetric elongation vibration mode extending (expanding and contracting in the radial direction) from the center to the outer peripheral direction and a non-axisymmetric in-plane vibration mode bending non-axisymmetrically in the same plane A structure using a child is disclosed, which is suitable for a thin structure and has features such as high speed and high thrust.

(Structure of vibrator) FIG. 5 is a view showing a conventional example of a vibrator of a vibration actuator utilizing a radially symmetric elongation vibration mode and a non-axisymmetric in-plane vibration mode. The vibrator 10 includes a piezoelectric element 11, an electrode 12, and the like. The piezoelectric element 11 is formed, for example, by forming a piezoelectric material such as PZT into a donut plate shape and polarizing the entire surface in the plate thickness direction. This donut plate shape has a radially symmetric elongation vibration mode (R, 1) and a non-axisymmetric in-plane vibration mode ((1,
It is designed and manufactured so that the resonance frequencies of 1)) become almost 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. 5 (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 / π) with the first AC voltage.
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 elongation 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. 5 (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 in FIG. 5 (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. 5A is generated at the position of the point (the driving force extracting portion) as a displacement obtained by combining the two vibrations.

(Operation of Vibration Actuator) As described above, the first and second electrodes 12 are driven by the drive voltage generator.
a and 12b are applied with the first and second AC voltages,
Elliptic motion occurs at the positions of C1 and C2 (drive force take-out parts). At this time, the sliding surface of the vibrator 10 and the relative motion member 3
Between 0 and 0, a frictional force is generated in the moving direction of the relative motion member 30, and a linear driving force of the relative motion member 30 can be obtained.

The phase difference between the first and second AC voltages is π / 2
, The straight traveling direction can be reversed. In order to reverse the driving direction, first and second
It is also possible by exchanging the AC voltage. Further, by moving the driving frequency closer to or farther from the resonance frequency of the vibrator, it is possible to increase or decrease the speed of the straight running operation. The speed can be increased or decreased by increasing or decreasing the AC voltage.

[0010]

However, as shown in FIGS. 5 (C) and 5 (D), the conventional vibration actuator described above has two nodes of vibration modes (points A, B1, B2).
Therefore, if the fixed support of the vibrator 10 is firmly performed, the vibration is suppressed, and there is a problem that the driving efficiency is reduced. Further, since the vibrator 10 is a thin plate, if the vibrator 10 is firmly fixed with screws or the like, it may be damaged. On the other hand, if loose play is caused by loose support, the controllability of positioning is reduced, and stable driving cannot be performed. Further, the vibrator has to be positioned on a support frame such as a housing and fixed with screws or the like, which is inferior in assemblability.

Japanese Patent Application Laid-Open No. 9-233867 discloses a structure in which a vibrator is inserted and fixed in a step portion of a column.
Since the column is strong, a chip may be generated at the time of insertion in the case of a vibrator made of piezoelectric ceramics or the like.
The struts may be made thinner, but sufficient pressure cannot be obtained when pressure is applied to the relative motion member.

SUMMARY OF THE INVENTION An object of the present invention is to provide a vibration actuator having a fixed support structure capable of positioning and supporting a vibrator with high precision without causing backlash and suppressing vibration, and which is easy to assemble. It is to be.

[0013]

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) that simultaneously generates a radially symmetric elongation vibration mode that expands and contracts in a radial direction and a non-axisymmetric in-plane vibration mode that bends non-axisymmetrically in the same plane.
A fixed hole (11a) located at the center of the vibrator, and a position regulating portion (2) inserted into the fixed hole and regulating the position of the vibrator.
2), wherein the position restricting portion forms a retaining portion (22c) of the vibrator by a caulked portion at the tip.

According to a second aspect of the present invention, in the vibration actuator according to the first aspect, the position restricting portion (22) includes:
The vibration actuator is characterized by being formed of a thermoplastic material, wherein the retaining portion (22c) is formed by heating and deforming the tip of the position regulating portion.

According to a third aspect of the present invention, there is provided the first or fourth aspect.
In the vibration actuator described in (1), at room temperature, a predetermined gap (d) is provided between the position restricting portion (22) and the fixing hole portion (11a) and in the vibration plane direction of the vibrator.
Is a vibration actuator.

According to a fourth aspect of the present invention, there is provided the first to third aspects.
In the vibration actuator according to any one of the above, the position of the vibrator (10) in the rotation direction is regulated by the engagement of the fixing hole (11a) with the position regulating portion (22). A vibration actuator.

According to a fifth aspect of the present invention, there is provided a vibrator (10) which simultaneously generates a radially symmetric elongation vibration mode which expands and contracts in a radial direction and a non-axisymmetric in-plane vibration mode which bends non-axisymmetrically in the same plane. In the method of manufacturing a vibration actuator using the method, the position regulating portion (2) inserted into the fixing hole (11a) located at the center of the vibrator to regulate the position of the vibrator.
A method of manufacturing a vibration actuator, comprising a step of forming a retaining portion (22c) of the vibrator by caulking the tip of 2).

According to a sixth aspect of the present invention, in the method of manufacturing a vibration actuator according to the fifth aspect, the step of forming the retaining portion comprises the step of forming the position restricting portion (2) made of a thermoplastic material.
2) A method for manufacturing a vibration actuator, wherein the tip is deformed by heating.

According to a seventh aspect of the present invention, in the method for manufacturing a vibration actuator according to the sixth aspect, in the step of forming the retaining portion, the heating tool is heated and deformed by pressing the heating tool. It is a manufacturing method.

According to an eighth aspect of the present invention, in the method of manufacturing a vibration actuator according to the sixth aspect, in the step of forming the retaining portion, the tool is heated and deformed by pressing a tool that performs ultrasonic vibration. This is a method for manufacturing a vibration actuator.

According to the ninth aspect of the present invention, there is provided the sixth aspect of the present invention.
In the manufacturing method of the vibration actuator according to any one of the above, the position restricting portion (22) and the fixing hole portion (11a) are subjected to heat deformation in the retaining portion forming step and then to thermal contraction. And a gap forming step of forming a predetermined gap (d) in the direction of the vibration plane of the vibrator (10).

[0022]

Embodiments of the present invention will be described below in more detail with reference to the drawings. FIG.
1 is a perspective view of a vibration actuator according to an embodiment of the present invention. FIG. 2 is a perspective view showing a state immediately before fixing the vibrator 10 to the base 20. Note that the same reference numerals are given to portions that perform the same functions as those of the above-described conventional example, and redundant description will be omitted as appropriate. The vibration actuator has a base 20, a vibrator 10, and a relative motion member 30.
In addition, by providing a pressurizing device, a movement guide device, and the like in addition to the above, a function as a vibration actuator is exhibited, but is omitted here.

The vibrator 10 is a vibrator that generates a radially symmetric elongation vibration mode and a non-axisymmetric in-plane vibration mode.
Piezoelectric element 11, first and second electrodes 12a, 12b
, A third electrode (not shown) on the back surface, and a sliding member 13. The piezoelectric element 11 is an electromechanical conversion element such as a piezoelectric ceramic, and in the present embodiment, PZT is used. The boundary between the first and second electrodes 12a and 12b is arranged along a line connecting two nodes of the non-axisymmetric in-plane vibration mode. Further, the vibrator 11 has an oval-shaped fixing hole 11a having a width of 3.000 mm at the center thereof.

The base 20 is a base on which the vibrator 10 is fixed, and has a position restricting portion 22 having a pedestal portion 21. The position restricting portion 22 is a shaft of polycarbonate (filled with 20% glass fiber) fixed on the base 20,
When combined with the fixing hole 11a, 0.050
It has an oval cross section with a width of 2.900 mm so that a gap of 1 mm is formed.
It is longer than the thickness of 0.

The horn 40 is a metal tool that vibrates ultrasonically, and is attached to an ultrasonic vibration generator (not shown).

Next, a process of fixing the vibrator 10 to the position regulating portion 22 will be described. FIG. 3 shows that the vibrator 10 is
FIG. 7 is a cross-sectional view showing a step of fixing to In addition, FIG.
FIG. 4 is an enlarged view of a portion A in FIG. (Step 1) First, the fixing hole 11a of the vibrator 10 is mounted so as to match the position regulating part 22 (FIG. 3A).

(Step 2) Next, the horn 40 is pressed against the distal end 22a of the position regulating portion 22 while being ultrasonically vibrated. The position regulating portion 22 generates heat by internal heating caused by friction with the horn 40 and ultrasonic vibration transmitted from the horn 40, and reaches a temperature of about 180 ° C. The polycarbonate used in the present embodiment has a heat deformation temperature of about 150 ° C.
Therefore, the tip 22a is thermally deformed and deforms following the tip shape of the horn 40 (FIG. 3B). Due to this deformation, a retaining portion 22b is formed at the tip of the position regulating portion 22. Further, at this time, the outer periphery of the position regulating portion 22 is deformed following the inner periphery of the fixing hole 11a, so that the vibrator 10
The play between the positioning and the position restricting portion 22 is completely eliminated.

(Step 3) Finally, the horn 40 is removed and naturally cooled at normal temperature [FIG. 3 (C) and FIG.
(D)]. Here, when the polycarbonate used for the material of the position restricting portion 22 is cooled from a high temperature state, it contracts in accordance with the amount of the temperature change. , A slight gap d is formed with the fixing hole 11a. If normal temperature is 20 ° C,
Natural cooling will lower the temperature by about 160 deg. Since the coefficient of thermal expansion of the polycarbonate used in the present embodiment is 3 × 10 ⁻⁵ / ° C., the width of the position regulating portion 22 was 3.000 mm at the stage following the fixing hole 11 a. Shrink to 2.986 mm. Therefore, the gap d between the position regulating section 22 and the fixing hole 11a is d = 0.0
07 mm (7 μm).

The vibration amplitude near the fixing hole 11a of the vibrator 10 is about 1 μm.
0 can be held. Further, since the gap before deforming the tip 22a was 0.050 mm, the play (gap) was about 1/7, and the play of mounting the vibrator 10 can be reduced. The piezoelectric element 11 (PZ
The temperature rise of T) is smaller than that of the position regulating part 22 and the deformation is small. Therefore, the deformation of the fixing hole 11a of the vibrator 10 is omitted for the sake of simplicity. Further, since the position restricting portion 22 also contracts in the axial direction simultaneously with contraction in the axial width direction, fixing in this direction is more reliable.

According to the present embodiment, the tip 22a of the position restricting portion 22 is deformed by heat to fix the vibrator 10, so that the operation is simple and the mass productivity is high. Also, the vibrator 1
The vibration required for the zero drive is in the in-plane direction, and does not hinder the vibration of the vibrator in this direction, and the out-of-plane direction can be reliably held. Furthermore, since the shaft is formed according to the shape of the fixing hole 11a, there is no variation and the mounting play can be made very small as compared with those obtained by a manufacturing method such as cutting or molding, so that the accuracy is improved. A vibration actuator having high driving efficiency and high driving efficiency can be manufactured.

(Modifications) Various modifications and changes are possible without being limited to the above-described embodiments, and these are also within the equivalent scope of the present invention. (1) In the present embodiment, the horn 40 that vibrates ultrasonically
Although an example of assembling the vibration actuator using is described above, the present invention is not limited to this, and a tool heated to a temperature equal to or higher than the thermal deformation temperature of the material is pressed against the tip
a may be heated and deformed. (2) In the present embodiment, an example in which the entire distal end 22a of the oval position restricting portion 22 is deformed has been described. However, the present invention is not limited thereto.
In addition to the oval shape, a plurality of rotation stop portions 122d and the like may be further provided. In addition, the shape of the retaining portion may be provided at a plurality of locations where a part of the distal end is partially deformed without being deformed as in the retaining portion 122c shown in FIG. (3) In the present embodiment, the material of the position regulating portion 22 is
Although an example in which polycarbonate is filled with 20% of glass fiber has been described, the present invention is not limited to this. For example, the ratio of glass fiber may be 10% or another ratio. Further, the material is not limited to polycarbonate, and may be, for example, a thermoplastic resin shown in Table 1.

[0032]

[Table 1]

[0033]

As described above, according to the present invention, the following effects can be obtained. (1) Since the stopper portion is provided at the tip of the position regulating portion, the holding of the vibrator can be simplified.

(2) Since the retaining portion is formed by heat deformation, it does not restrict the necessary vibration of the vibrator.
It is possible to manufacture a vibration actuator having a very small play.

(3) Since a heating tool is used, the cost of the tool can be reduced, and the price of the vibration actuator can be reduced.

(4) Since the ultrasonic vibration is used, the deformation of the position restricting portion can be accurately controlled, and the accuracy is high.
A highly reliable vibration actuator can be manufactured.

(5) Since the rotation of the vibrator is stopped by the engagement between the fixing hole and the position restricting portion, the rotation of the vibrator can be surely stopped.

(6) Since a predetermined gap is provided between the position regulating portion and the fixing hole, the vibrator can be securely fixed without obstructing necessary in-plane vibration of the vibrator.

[Brief description of the drawings]

FIG. 1 is a perspective view of a vibration actuator according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a state immediately before fixing a vibrator to a base.

FIG. 3 is a cross-sectional view showing a step of fixing the vibrator 10 to a base 20.

FIG. 4 is a diagram showing a modification of the shape of the position regulating unit.

FIG. 5 is a view showing a conventional example of a vibrator of a vibration actuator using a radially symmetric elongation vibration mode and a non-axisymmetric in-plane vibration mode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Vibrator 11 Piezoelectric element 12a, 12b Electrode 13 Sliding material 20 Base 21 Pedestal part 22 Position control part 30 Relative motion member 40 Horn

Claims (9)

[Claims] 1. A vibration actuator using a vibrator that simultaneously generates a radially symmetric elongation vibration mode that expands and contracts in a radial direction and a non-axisymmetric in-plane vibration mode that bends non-axisymmetrically in the same plane, A fixed hole located at the center of the vibrator, and a position restricting portion inserted into the fixed hole and restricting the position of the vibrator, wherein the position restricting portion is formed by crimping the tip of the vibrator. A vibration actuator having a retaining portion. 2. The vibration actuator according to claim 1, wherein the position restricting portion is formed of a thermoplastic material, and the retaining portion is formed by heating and deforming a tip of the position restricting portion. A vibration actuator. 3. The vibration actuator according to claim 1, wherein at a room temperature, a predetermined gap is provided between the position restricting portion and the fixing hole and in a direction in a vibration plane of the vibrator. Is present, the vibration actuator. 4. One of claims 1 to 3
The vibration actuator according to any one of the preceding claims, wherein the vibrator has its position in the rotation direction restricted by engaging the fixing hole with the position restriction part. 5. A method of manufacturing a vibration actuator using a vibrator that simultaneously generates a radially symmetric elongation vibration mode that expands and contracts in a radial direction and a non-axisymmetric in-plane vibration mode that bends non-axisymmetrically in the same plane. In the above, a stopper forming step of forming a stopper of the vibrator by caulking a tip of a position restricting part inserted into a fixing hole located at the center of the vibrator and restricting a position of the vibrator. A method for manufacturing a vibration actuator, comprising: 6. The vibration actuator according to claim 5, wherein in the step of forming the retaining portion, the tip of the position regulating portion made of a thermoplastic material is heated and deformed. Manufacturing method. 7. The method of manufacturing a vibration actuator according to claim 6, wherein in the retaining portion forming step, the heating tool is heated and deformed by pressing the heating tool. 8. The method of manufacturing a vibration actuator according to claim 6, wherein the retaining portion forming step is performed by heating and deforming by pressing a tool that performs ultrasonic vibration. Production method. 9. Any one of claims 6 to 8
In the manufacturing method of the vibration actuator according to the above, after performing the heating deformation in the retaining portion forming step, by heat contraction, between the position regulating portion and the fixing hole portion of the vibrator A method for manufacturing a vibration actuator, comprising: a gap forming step of forming a predetermined gap in an in-vibration plane direction.