JP2002058267A - Vibration actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic actuator increasing the degree of freedoms of an object to be driven in a driving direction without bringing about an increase in size, in weight, in complexity, in cost, in noise or further in low response or the like of a driving system. SOLUTION: The ultrasonic actuator 10 comprises a vibrator 15 having a driving force outputting unit 14, and a driver 16 capable of forming a periodical displacement obtained by synthesizing an (R, 1) vibration, a ((1, 1)) vibration and a B12 vibration excited at the vibrator 15 and forming a periodical displacement at the unit 14 by switching and exciting at least two types of these three types of the vibrations.

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 an increased degree of freedom in a driving direction of an object to be driven.

[0002]

2. Description of the Related Art FIG.
It is a perspective view which shows the structure of an example. FIG. 14 is an explanatory diagram showing waveform examples of two vibrations L1 and B4 generated in the vibrator 2 of the vibration actuator 1. Since an ultrasonic actuator utilizing an ultrasonic vibration region is known as this type of vibration actuator 1, the following description will use an ultrasonic actuator as an example.

[0003] As shown in FIG. 13, in the conventional ultrasonic actuator 1, input regions 4 a and 4 b of a piezoelectric element 4 provided on one plane of an elastic body 3 constituting a vibrator 2 are provided.
Through the electrodes 5a and 5b, two-phase drive signals (AC voltages) V _A and V _B having phases different from each other by about (π / 2) and having a predetermined frequency are input, respectively. This allows
As shown in FIG. 14, a primary longitudinal vibration L1 and a fourth-order bending vibration B4 having different phases are excited in the elastic body 3.

[0004] These two vibrations L1 and B4 are synthesized together, and the driving force output portions 3a, 3b provided on the elastic body 3 are provided.
In addition, they are periodically displaced in an elliptical shape and their phases are π
Displaced elliptical motions occur respectively. For this reason, the ultrasonic actuator 1 linearly frictionally drives the driving object 6 that comes into pressure contact with the driving force extracting portions 3a and 3b in one direction (the left and right directions in FIGS. 13 and 14).

[0005] As described above, the conventional ultrasonic actuator forms an elliptical periodic displacement in the driving force take-out portion by combining two types of vibrations excited in the vibrator, and makes pressure contact. A so-called two-mode degenerate type vibrator that frictionally drives an object to be driven has been used.

[0006]

In recent years, there has been an increasing demand for miniaturization and multi-functionality of various apparatuses and further reduction in cost. For example, small XY stages, joints of various robots, and other precision equipment, etc., realize small, high thrust, quietness, and low cost, as well as flexible mechanical operation, specifically, two freedoms. Realization of driving with multiple degrees of freedom such as degrees and three degrees of freedom has been strongly demanded.

However, in order to drive the driving object 6 with multiple degrees of freedom using the conventional ultrasonic actuator 1, it is necessary to use at least the same number of ultrasonic actuators 1 as the required number of degrees of freedom. . That is, as described above, the driving direction of the conventional ultrasonic actuator 1 is limited to one direction parallel to the direction in which the elliptical periodic displacement occurs, and is an operation with one degree of freedom. Therefore, in order to drive the driving target 6 in, for example, two directions by the ultrasonic actuator 1, it is necessary to use at least two ultrasonic actuators 1 in combination.

In order to drive the driving object 6 in two directions by the two ultrasonic actuators 1 as described above,
The vibrators 2 of these two ultrasonic actuators 1 need to be brought into pressurized contact with the driving target 6 via the respective driving force extracting portions 3a and 3b. For this reason, in order to prevent the contact of the other ultrasonic actuator 1 from acting as a brake when driven by one ultrasonic actuator 1, each of the transducers 2 and the object 6 to be driven are controlled.
For example, an electromagnetic clutch may be interposed between them, or a bending vibration B4 may be generated also in the vibrator 2 of the ultrasonic actuator 1 when it is not driven to reduce the frictional resistance with the driven object 6 as much as possible. There was also a need to make special contrivances.

[0009] A gear is interposed between the ultrasonic actuator 1 and the object 6 to be driven, and the gear is appropriately switched to change the driving direction each time. Driving in two directions is technically possible. However, in this case, the configuration of the drive system is considerably complicated, so that the cost and the frequency of failures cannot be denied, and the drive target 6 is not directly driven by the ultrasonic actuator 1, so that the start and stop are performed. Responsiveness, etc., is significantly reduced.

As described above, when the object 6 to be driven is driven by the conventional ultrasonic actuator 1 with a large number of degrees of freedom, the drive system becomes large, heavy, complicated, and expensive.
High noise and low response were inevitable, and this was a major technical problem.

An object of the present invention is to provide a vibration actuator, such as an ultrasonic actuator, having an increased degree of freedom in the driving direction of an object to be driven, by increasing the size, weight, complexity, and cost of the drive system. It is an object of the present invention to provide high noise and low responsiveness.

[0012]

According to the present invention, it is possible to excite three kinds of vibrations including a so-called vertical vibration, and to generate a driving force in a driving force take-out section by combining these three kinds of vibrations. By using a new vibrator capable of driving, it is possible to increase the degree of freedom in the driving direction, whereby it is possible to drive the driven object in two or three directions by one vibration actuator. It is based on new and important findings.

According to the first aspect of the present invention, a vibrator having a driving force extracting portion is provided, and the first vibration, the second vibration, and the third vibration excited by the vibrator are combined with the driving force extracting portion. The invention provides a vibration actuator characterized by being able to form a controlled periodic displacement.

According to a second aspect of the present invention, in the vibration actuator according to the first aspect, the first vibration, the second vibration, and the third vibration vibrate in directions intersecting each other.

[0015] The invention of claim 3 is claim 1 or claim 2.
In the vibration actuator described in the above, a driving device that forms a periodic displacement in the driving force take-out unit by switching and exciting at least two of the first vibration, the second vibration, and the third vibration It is characterized by having.

According to a fourth aspect of the present invention, there is provided the first to third aspects.
In the vibration actuator described in any one of the above, the vibrator has an annular shape,
Is a symmetric elongation vibration, the second vibration is an in-plane bending vibration, and the third vibration is a plane-perpendicular vibration.

According to a fifth aspect of the present invention, in the vibration actuator according to the fourth aspect, the symmetric elongation vibration is (R,
1) a vibration, a plane bending vibration ((1,1)) vibrations, and wherein the further surface vertical vibration is B ₁₂ vibration.

[0018] The invention of claim 6 is the vibration actuator according to claim 5, the vibrator, the driving signal input regions provided respectively by two sections located four compartments resulting in the radial direction of the B ₁₂ vibration And the drive device can independently control the phases of the drive signals input to these drive signal input areas.

Further, according to a seventh aspect of the present invention, in the vibration actuator according to the sixth aspect, the driving device comprises:
(R, 1) vibration and ((1,1)) and the periodic displacement in the first direction by exciting vibrations, (R, 1) the first direction due to excite vibrations and B ₁₂ vibration A periodic displacement in a second direction different from the (R, 1) vibration,
((1,1)) by switching the vibration and periodic displacement of B ₁₂ vibration to the third direction in which the first and second directions due to excitation is synthesized, formed on the driving force output portion It is characterized by doing.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) Hereinafter, embodiments of a vibration actuator according to the present invention will be described in detail with reference to the accompanying drawings. In the following description of each embodiment, a case where the vibration actuator is an ultrasonic actuator using an ultrasonic vibration region is taken as an example.

FIG. 1 is an explanatory diagram showing the configuration of an ultrasonic actuator 10 according to the present embodiment. FIGS. 2A and 2B are explanatory diagrams showing the arrangement of the electrodes 13 of the ultrasonic actuator 10. FIG. 2A is a plan view, and FIG.
FIG. 2A is a cross-sectional view taken along line AA, and FIG. 2C is a bottom view.

As shown in FIG. 1, an ultrasonic actuator 10 according to the present embodiment includes a vibrator 1 having an elastic body 11, an electromechanical transducer 12, an electrode 13, and a driving force output portion 14.
5 and a driving device 16. Hereinafter, these components of the ultrasonic actuator 10 of the present embodiment will be sequentially described.

In the present embodiment, the elastic body 11 is formed in an annular shape from brass, but is not limited to brass.
It may be made of a material having a large resonance sharpness, such as ordinary steel, a copper alloy other than brass, and stainless steel.

As will be described later, (R, 1) vibration,
((1,1)) for degenerate vibration of three substantially aligned with respective resonant frequencies of vibration and B ₁₂ vibrating,
In the present embodiment, the dimensions of each part of the elastic body 11 are set such that the inner / outer diameter ratio (b / a), which is the ratio of the inner diameter b to the outer diameter a of the annular elastic body 11, is approximately 0.3. .

On two planes of the elastic body 11,
Electromechanical transducers 12a and 12b formed in an annular shape with the same outer diameter and inner diameter as the elastic body 11 are attached, for example, by bonding. In the present embodiment, the electromechanical transducer 12
Electrostrictive elements made of PZT (lead titanium zirconate) were used as a and 12b.

An electrode 13 is mounted on the surface of each of the electromechanical transducers 12a and 12b mounted on the elastic body 11. In the present embodiment, a silver electrode is used as the electrode 13. Electrode 1 mounted on surface of electromechanical transducer 12a
3 is a fan-shaped four electrodes 13a, 13b, 13c, 13
d. On the other hand, the electrodes 13 mounted on the surface of the electromechanical transducer 12b also have four fan-shaped electrodes 13.
e, 13f, 13g, and 13h.

The electrode 13a and the electrode 13g are mounted in the same range in the thickness direction of the elastic body 11, the electrode 13b and the electrode 13f are mounted in the same range in the thickness direction of the elastic body 11, and the electrode 13c and the electrode 13c are mounted in the same range. The electrode 13e is an elastic body 11
Are mounted in the same range in the thickness direction of the elastic body 11, and the electrodes 13d and 13h are mounted in the same range in the thickness direction of the elastic body 11.

As will be described later with reference to FIG. 6, electrodes 13a and 13g, electrodes 13b and 13f, and electrodes 13c
And 13e, and the electrodes 13d and 13h,
1 linearly occurring two nodal positions to B ₁₂ radial direction of the vibration to be excited (Fushi径) 19a, into four regions partitioned by 19b, respectively, and adjacent ones are electrically insulated from each other Be attached. As a result, the vibrator 15
These two Fushi径19a of B ₁₂ vibrating, the four input regions partitioned by 19b has on both sides of the vibrator 15, a total of eight driving signal input region corresponding to the electrode 13a~13h is formed I have.

Leads 17a to 17h are connected to the electrodes 13a to 13h, for example, by soldering.
It is connected to an output section of a drive circuit built in a drive device 16 described later.

A drive signal (AC voltage) whose phases are controlled independently from the drive device 16 to be described later is applied to each of the electrodes 13a to 13h so that the brass elastic body 11 has a ground potential. , Are input via the lead wires 17a to 17h.

By appropriately setting the phase of each drive signal input to each of the electrodes 13a to 13h, the elastic body 1
At least one of the first vibration, the second vibration and the third vibration is excited in the first vibration.

The first vibration excited by the elastic body 11 is a symmetric elongation vibration that radially expands and contracts radially from the approximate center of the elastic body 11, and is (R, 1) vibration in the present embodiment. . The second vibration is an in-plane bending vibration that bends and deforms in the plane of the elastic body 11, and in the present embodiment, ((1,
1)) Vibration. Further, the third vibration is caused by the elastic body 11
A bent and deformed to plane-vertical vibration in the out-of-plane, in this embodiment a B ₁₂ vibration. Hereinafter, (R, 1) vibration excited by the elastic body 11 in the present embodiment, ((1, 1))
Sequentially described vibrations and B ₁₂ vibrations.

(I) (R, 1) Vibration FIG. 3 is an explanatory diagram schematically showing a state of displacement due to (R, 1) vibration generated in the elastic body 11 in the present embodiment.

That is, as shown in FIG. 3, (R, 1)
The vibration is a symmetric elongation vibration in which the diameter of the elastic body 11 increases and decreases in the radial direction, and FIG. 3 shows a state when the diameter is reduced. At the timing shown in FIG. 3, mass points B and B ′ and mass points C and C ′ located at the center in the thickness direction on the outer peripheral surface of the elastic body 11.
Have a displacement component Ur in the radially-reducing direction.

(Ii) ((1, 1)) Vibration FIG. 4 is an explanatory view schematically showing a state of displacement caused by ((1, 1)) vibration generated in the elastic body 11 in the present embodiment. is there.

That is, as shown in FIG.
1)) The vibration is an in-plane bending vibration centered on mass points D and D ′ located at the center in the thickness direction on the outer peripheral surface of the elastic body 11. Note that the mass points D and D ′ have a displacement component Uθ in the direction of the arrow, and the mass points E and E ′ that are at positions orthogonal to the mass points D and D ′ with respect to the center of the elastic body 11 are
Each of the extension displacement and the contraction displacement as indicated by arrows in FIG. 4 alternately occurs in accordance with the cycle.

(Iii) B ₁₂ Vibration FIG. 5 shows B ₁₂ generated in the elastic body 11 in the present embodiment.
FIG. 9 is an explanatory diagram schematically showing a state of displacement due to ₁₂ vibrations. FIG. 6 shows one example of B ₁₂ vibration generated in the elastic body 11.
It is explanatory drawing which shows typically the generation | occurrence | production situation of two nodal circles 18 and two nodal diameters 19a and 19b.

That is, as shown in FIG. 5 and FIG. 6, the B ₁₂ vibration is a bending vibration of the elastic body 11 in the out-of-plane direction (thickness direction), and one node position generated in a circular shape. This is bending vibration in the thickness direction of the elastic body 11 having a (knot circle) 18 and two knot positions (knot diameters) 19a and 19b that are linearly generated in the radial direction. Therefore, the direction of displacement of the elastic body 11 according to B ₁₂ vibrations along the circumferential direction of the elastic body 11, two Fushi径19a, express reversed four times every four regions partitioned by 19b.

In this embodiment, two nodal diameters 19a, 1
9b, four electrodes 13a
To 13d and the electrodes 13e to 13h are electrically insulated by placing the adjacent electrodes apart from each other and mounted. Therefore, in the present embodiment, the vibrator 15, two nodal positions occur in the radial direction of the B ₁₂ vibration 19
a, the input area divided into four areas by 19b
5 on both sides, for a total of eight drive signal input areas.

[0040] The B ₁₂ vibrating the elastic body 11, elastic body 1
The material points D and D ′ which vibrate in a direction intersecting with the plane 1 (thickness direction of the elastic body 11) and are located on the circumference of the elastic body 11 are
It has a displacement component Up in the direction of the arrow in FIG. 5 (the thickness direction of the elastic body 11).

As shown by arrows Ur, Uθ and Up in FIGS. 3 to 5, respectively, (R, 1) vibration, ((1,
1)) vibration directions of the respective vibrating and B ₁₂ vibration is a direction crossing each other.

As described above, in the present embodiment, as shown in FIGS. 1 and 2 described above, the electrodes 13a to 13d mounted on one plane of the elastic body 11 and the other plane of the elastic body 11 Each of the electrodes 13e to 13h mounted on the side is divided into four parts, and these electrodes 13a to 13h are further divided into two groups, so that a total of eight drive signal input areas are formed on the vibrator 15. Therefore, by inputting drive signals having phases opposite to each other between adjacent ones of the eight drive signal input areas and corresponding ones on the upper and lower surfaces, bending generated on both surfaces of the elastic body 11 is performed. The displacement can be made non-uniform. Therefore, according to this embodiment, it is possible to excite the B ₁₂ oscillate at high efficiency.

Incidentally, are excited in the vibrator 15 of the present embodiment (R, 1) vibration, ((1,1)) for each vibration and B ₁₂ vibrations per se, "New Edition Ultrasonic Motor" (Triceps published , Ueha Sadayuki and Tomikawa Yoshiro), and further description is omitted.

FIG. 7 shows an inner / outer diameter ratio (b / a) of the elastic body 11.
6 is a graph showing an example of a relationship between each resonance frequency f of (R, 1) vibration, ((1, 1)) vibration, and B ₁₂ vibration. In FIG. 7, reference symbol a represents the outer diameter of the annular elastic body 11, and reference numeral b represents the inner diameter of the annular elastic body 11. The result shown in FIG.
This is a case where the thickness t of the substrate 1 is 0.6 mm.

As shown in the graph, when the thickness of the elastic body 11 is 0.6 mm, the inner / outer diameter ratio (b / a)
If the set to be approximately 0.25 to 0.35 range, (R, 1) vibration, ((1,1)) these for the respective resonant frequencies of vibration and B ₁₂ vibration substantially coincides Three vibrations can be degenerated. In order to reliably degenerate these three vibrations, the inner / outer diameter ratio (b / a) of the elastic body 11 is preferably 0.27 or more and 0.33 or less, and is 0.29 or more and 0.31 or less. It is even more desirable.

As described above, in the vibrator 15 of the present embodiment, by appropriately setting the thickness t and the inner / outer diameter ratio (b / a), the (R, 1) vibration, the ((1, 1)) ) Vibration and B
It is possible to degenerate ₁₂ vibrations. In the present embodiment, the thickness of the elastic body 11 is about 1.2 mm, and the inner / outer diameter ratio (b /
By setting a) to about 0.3, (R, 1) vibration,
((1,1)) was degenerated three vibration of the vibration and the B ₁₂ vibrations.

Further, in this embodiment, FIGS. 1 and 2
As shown in the figure, a driving force take-out portion 14 is provided to protrude from the mass point D. The driving force extracting portion 14 is a sliding member mainly composed of a polymer material or the like.
E, polyimide resin, PEN, PPS, PEEK and the like are exemplified. The driving force output unit 14, is excited in the elastic member 11 (R, 1) vibration, ((1,1)) vibration and elliptical periodic displacement is formed as the synthesis of B ₁₂ vibration, it is taken it can.

FIG. 8 is a block diagram showing a driving circuit of the driving device 16. The oscillator 20 oscillates a signal having a resonance frequency (frequency f ₁ in FIG. 7) common to the (R, 1) vibration, the ((1, 1)) vibration, and the B ₁₂ vibration excited by the vibrator 15. The output of the oscillator 20 is branched into eight and input to the phase shifter 21. In the phase shifter 21, the phase of each input signal is appropriately set and changed. The eight signals whose phases are appropriately set by the phase shifter 21 are respectively supplied to the amplifiers 22.
a to 22h and amplified to a predetermined value.
17a to 17h and electrodes 13a to 13
The signals are input to eight drive signal input areas formed on the vibrator 15 via the input signals h.

As described above, the driving device 16 of the present embodiment includes the electrodes 13a to 13a on one plane of the vibrator 15.
13d and an electrode 13e on the other plane of the vibrator 15.
To 13h can be independently controlled.

Table 1 shows that when driving signals having various phases are input to the respective electrodes 13a to 13h using the driving device 16 of the present embodiment, the vibration excited by the vibrator 15 and the driving force The driving force generation directions appearing in the take-out unit 14 are shown together. Hereinafter, the generation of the driving force generated in the vibrator 15 of the present embodiment will be described with reference to Table 1 and FIGS. 2A to 2C.

[0051]

[Table 1] The electric input patterns A to C in Table 1 are respectively
(R, 1) vibration, and ((1,1)) vibrations, if B ₁₂ vibration is excited alone. In this case, no elliptical periodic displacement occurs in the driving force extracting portion 14 of the vibrator 15, so that no driving force is generated in the driving force extracting portion 14.

Next, the electric input patterns D,
E is a case where (R, 1) vibration and ((1, 1)) vibration are excited. In this case, a plane parallel to the plane of the vibrator 15 (X in FIG. 2A or FIG. 2C)
Since an elliptical displacement oscillating inward is generated, a one-dimensional driving force in a certain direction (first direction) in the XY plane is generated in the driving force extraction unit 14.

Next, the electric input patterns F,
G are both a case where (R, 1) vibration and B ₁₂ vibration is excited. In this case, an elliptical displacement oscillating in a plane intersecting with the plane of the vibrator 15 (the YZ plane in FIG. 2B) is generated. A one-dimensional driving force is generated in the direction (second direction).

Further, the electric input pattern H in Table 1
Is when (R, 1) vibration, ((1,1)) vibrations and B ₁₂ vibrations are both excited. In this case, the driving force extraction unit 14 has a one-dimensional direction in a third direction in which the first direction and the second direction are combined in the XYZ space shown in FIGS. 2A to 2C. Driving force is generated.

As described above, according to the present embodiment, the following effects can be obtained. (1) In the present embodiment, the vibrator 15 having an annular outer shape is used, and the inner / outer diameter ratio (b / a) is optimally set. ((1, 1)) vibration which is an internal bending vibration and B which is a plane perpendicular vibration
₁₂ vibrations and can be excited.

For this reason, in the present embodiment, the vibrator 15
Is a first vibration (R, 1) is a vibration and a second vibration ((1,1)) vibration and the B ₁₂ vibration and a third vibration exciting, of these three It is possible to form a periodic displacement in which the vibrations are synthesized in the driving force output unit 14. That is, in the XYZ space shown in FIGS. 2A to 2C, a first direction which is a driving force generation direction by excitation of the (R, 1) vibration and the ((1, 1)) vibration; the (R, 1) the driving force to the third direction is a synthetic direction of the second direction is a direction of a generated driving force by excitation of the vibrations and B ₁₂ vibrating,
It can be taken out from the driving force take-out part 14. As described above, it is possible to take out the driving force in the third direction, which has not been obtained by the conventional ultrasonic actuator, so that the ultrasonic actuator 10 is installed with respect to the driving target (installation position, installation posture, and the like). Can be increased more than before. Therefore, it is possible to improve the mountability of the ultrasonic actuator 10 particularly in narrow portions of various devices.

(2) In the present embodiment, the driving device 16 controls the first vibration (R, 1), the second vibration ((1, 1)), and the third vibration. it is possible to form a cyclic displacement driving force output portion 14 by exciting switching the at least two vibration of certain B ₁₂ vibrating in a first direction, the second direction and the third direction Driving forces in three directions can be generated by one ultrasonic actuator 10. For this reason, the degree of freedom of the driving direction of the driving target by the ultrasonic actuator 10 can be increased as compared with the related art.

At this time, it is not necessary to use another ultrasonic actuator as a drive source, and it is not necessary to interpose a gear or an electromagnetic clutch between the ultrasonic actuator 10 and the object to be driven. . For this reason, the complication of the drive system can be suppressed, and an increase in cost and an increase in failure frequency can be prevented.

Further, since it is possible to maintain that the driving object is directly driven by the ultrasonic actuator 10, it is possible to prevent a decrease in responsiveness in starting and stopping. Therefore, according to the present embodiment, the driving direction of the driving object can be freely controlled without increasing the size, weight, complexity, cost, noise, and response of the driving system. It is possible to increase the degree.

(3) In the present embodiment, the driving force extracting unit 1
Includes a vibrator 15 having an annular shape and has a 4, a driving force output portion 14, and B ₁₂ vibration is excited the plane perpendicular vibrations in the vibrator 15, in-plane bending vibration excited in the vibrator 15 A certain (R, 1) vibration or a periodic displacement in which the (R, 1) vibration and the ((1, 1)) vibration are combined can be formed. Therefore, not only in a plane (YZ plane) orthogonal to the plane of the vibrator 15 but also in a plane (X
Even within the (Y plane), an elliptical periodic displacement is formed,
Any of these periodic displacements can be extracted from the driving force extraction unit 14. For this reason, the degree of freedom in the driving direction of the driving target by the ultrasonic actuator 10 can be increased.

(Second Embodiment) FIG. 9 is an explanatory view schematically showing a configuration example of a small XY stage 23 using the ultrasonic actuator 10 of the first embodiment as a drive source. is there. In the following description of each embodiment, portions different from the above-described first embodiment will be described, and common portions will be denoted by the same reference numerals in the drawings, and duplicate description will be appropriately made. Omitted.

The vibrator 15 is supported by appropriate means by a support member 24 having a U-shaped outer shape. Also,
A pressing force generating member (not shown) such as a coil spring is provided outside the supporting member 24, and the pressing member P generates the pressing force by the pressing force generating member.
Is urged toward the driving target 25. For this reason, the driving force extracting unit 1 of the vibrator 15
4 makes pressure contact with the surface 25a of the driven object 25 with an appropriate pressure P.

The driving object 25 includes a plurality of rollers 2.
By 6a and 26b, it is movably supported in a plane parallel to the XY plane. At this time, the driving device 16 outputs the electric input pattern D or the electric input pattern E shown in Table 1 described above.
When the phases of the drive signals input to the electrodes 13a to 13h are controlled according to the following formula, as shown in Table 1, X in FIG.
Driving force in two directions, i.e., the direction and the Y direction, can be generated in the driving force extracting portion 14 of the vibrator 15.

Therefore, the driving object 25 that comes into pressure contact with the vibrator 15 via the driving force extracting portion 14 can be driven in two directions, the X direction and the Y direction. As described above, according to the present embodiment, one ultrasonic actuator 10 can drive an extremely small and simple XY stage 23 in two directions.

(Third Embodiment) FIG. 10 schematically shows a situation in which the ultrasonic actuator 10 according to the first embodiment is applied as a drive source for a joint of a wrist axis in a multi-axis electric robot. FIG. FIG. 11 is a sectional view taken along the line GG in FIG.

The two wrist shafts 27 and 28 of the multi-axis electric robot extend in directions substantially orthogonal to each other.
Each of the two wrist axes 27 and 28 has a spherical connection part 2.
9. The driving force output portion 14 of the vibrator 15 supported by the support member 24 comes into pressure contact with the upper portion of the outer peripheral surface of the connection portion 29 with the pressing force P. The connecting portion 29 is formed by a thrust bearing 31 having a plurality of rollers 31a in two directions in the XY direction and the YZ direction in FIG.
It is supported rotatably in the direction.

At this time, the driving device 16 outputs the above-mentioned Table 1
When the phases of the drive signals input to the electrodes 13a to 13h are controlled in accordance with the electric input patterns D to G shown in FIG.
Driving force in the YZ direction and the YZ direction can be generated in the driving force extraction unit 14.

For this reason, the spherical connecting portion 29 which comes into pressure contact with the vibrator 15 via the driving force extracting portion 14 is connected to the XY
The wrist shafts 27 and 28 are tilted in the vertical plane by rotating the wrist shaft 27 in the vertical direction, and the wrist shaft 27 is rotated about the rotation axis and the wrist shaft 28 is tilted in the vertical plane by driving in the YZ directions. It becomes possible to operate.

As described above, according to the present embodiment, the joints of the wrist shafts 27 and 28 in the multi-axis electric robot are
It could be driven by a very small and simple drive source.

(Fourth Embodiment) FIG. 12 is a perspective view showing a configuration example of a vibrator 15-1 according to the present embodiment. In the present embodiment, instead of providing the electromechanical transducers 12a and 12b on both sides of the elastic body 11, the electromechanical transducer 12a is provided on one face of the elastic body 11 and the electrodes 13a, 13b and 13c are provided on the surface thereof. , 13d.

Since the elastic body 11 is made of conductive brass, it is used as the ground electrode of the electromechanical transducer 12a. Also in the vibrator 15-1 of the present embodiment, when the phases of the drive signals input to the electrodes 13 a to 13 d are controlled in accordance with the electric input patterns D to G shown in Table 1 described above, Table 1 shows like,
The driving force in the XY direction and the YZ direction in FIG.

Further, according to the present embodiment, the usage of the electromechanical transducer 12 is reduced, and the manufacturing cost of the vibrator 15-1 is suppressed. As still another embodiment, although not shown, the electromechanical transducer 12 can be used without using the elastic body 11.
electrodes 13a, 13a directly on the front and back surfaces of
By attaching b, 13c, and 13d, the same operation as in the present embodiment can be performed even if a vibrator is configured.

(Modification) In the description of each embodiment, the case where the vibration actuator is an ultrasonic actuator is taken as an example. However, the present invention is not limited to the ultrasonic actuator, and is similarly applied to a vibration actuator using another vibration region.

In the description of each embodiment, the vibrator has an annular outer shape, generates symmetric elongation vibration as the first vibration, generates in-plane bending vibration as the second vibration, and The case where the plane vertical vibration is generated as the third vibration is taken as an example. However, this form is an exemplification of the present invention, and the present invention is not limited to this form. That is, in the present invention, a periodic displacement in which the first vibration, the second vibration, and the third vibration excited in the vibrator are combined is formed in the driving force extracting portion formed in the vibrator. Where possible, the same applies, and there is no limitation on the shape of the vibrator or the type of vibration generated in the vibrator.

Further, in the description of each embodiment, the symmetric elongation vibration is (R, 1) vibration, the in-plane bending vibration is ((1, 1)) vibration, and the plane perpendicular vibration is B ₁₂
The case of vibration is taken as an example. However, the present invention
(R, 1) vibration, ((1,1)) is not limited to a combination of vibration and B ₁₂ vibration, symmetric stretch vibration, also other combinations of plane bending vibration and the plane-vertical vibration, equally applicable It is. For example, the plane-vertical vibration, in addition to B ₁₂ vibrating,
B ₁₃ vibrating, B ₁₄ vibrating, B ₁₅ vibrating more B ₂₁ vibrations and the like.

[0076]

As described in detail above, claims 1 to 5
According to the seventh aspect of the present invention, a vibration actuator such as an ultrasonic actuator having an increased degree of freedom in the driving direction of an object to be driven can be provided by increasing the size, weight, complexity, cost, and cost of the drive system. The present invention was able to be provided without causing noise reduction and low response.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of an ultrasonic actuator according to a first embodiment.

FIG. 2 is an explanatory view showing an arrangement of electrodes of the ultrasonic actuator according to the first embodiment. FIG. 2A is a plan view,
FIG. 2B is a sectional view taken along line AA in FIG.
(C) is a bottom view.

FIG. 3 is an explanatory diagram schematically showing a state of displacement due to (R, 1) vibration generated in an elastic body according to the first embodiment.

FIG. 4 is an explanatory diagram schematically showing a state of displacement caused by ((1, 1)) vibration generated in the elastic body in the first embodiment.

FIG. 5 shows B generated in the elastic body according to the first embodiment.
FIG. 9 is an explanatory diagram schematically showing a state of displacement due to ₁₂ vibrations.

FIG. 6 shows B generated in the elastic body according to the first embodiment.
It is explanatory drawing which shows typically the generation | occurrence | production situation of one node circle and two node diameters of ₁₂ vibrations.

FIG. 7 is a diagram showing an inner / outer diameter ratio (b / a) of an elastic body and (R, 1) vibration.
Dynamic, ((1,1)) vibration and B ₁₂Each resonance of vibration
Graph showing an example of the relationship with the frequency f for each vibration
It is.

FIG. 8 is a block diagram showing a driving circuit of the driving device.

FIG. 9 is an explanatory diagram schematically showing a configuration example of a small XY stage using the ultrasonic actuator according to the first embodiment as a drive source.

FIG. 10 is an explanatory diagram schematically showing a situation in which the ultrasonic actuator according to the first embodiment is applied as a drive source for a joint portion of a wrist shaft in a multi-axis electric robot.

11 is a sectional view taken along the line GG in FIG.

FIG. 12 is a perspective view illustrating a configuration example of a vibrator according to a fourth embodiment.

FIG. 13 is a perspective view showing a configuration of an example of a conventional vibration actuator.

FIG. 14 is an explanatory diagram showing waveform examples of two vibrations L1 and B4 generated in a vibrator of a conventional vibration actuator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Ultrasonic actuator 11 Elastic body 12a, 12b Electromechanical conversion element 13a-13h Electrode 14 Driving force extraction part 15 Vibrator 16 Drive device 17a-17h Lead wire

Claims (7)

[Claims] An oscillator having a driving force extracting portion, wherein the driving force extracting portion includes first and second vibrations excited by the oscillator;
A vibration actuator capable of forming a periodic displacement in which the first vibration and the third vibration are combined. 2. The vibration actuator according to claim 1, wherein the first vibration, the second vibration, and the third vibration vibrate in directions crossing each other. 3. A drive device for switching and exciting at least two of the first vibration, the second vibration, and the third vibration to form a periodic displacement in the driving force extracting unit. The vibration actuator according to claim 1 or 2, wherein: 4. The vibrator has an annular shape, the first vibration is a symmetric elongation vibration, and the second vibration is
4. The vibration actuator according to claim 1, wherein the vibration is an in-plane bending vibration, and the third vibration is a plane-perpendicular vibration. 5. Wherein said symmetrical elongation vibration is (R, 1) vibration, the in-plane bending vibration is a vibration ((1,1)), characterized in that further the surface vertical vibration is B ₁₂ vibration The vibration actuator according to claim 4, wherein Wherein said vibrator, and having a drive signal input region provided in four compartments by two node positions caused to the radial direction of the B ₁₂ vibration, the drive apparatus, the drive signal input region 6. The vibration actuator according to claim 5, wherein the phases of the drive signals input to each of the actuators can be independently controlled. 7. The (R, 1) vibration, wherein the driving device comprises: a cyclic displacement in a first direction by exciting the (R, 1) vibration and the ((1, 1)) vibration; And a periodic displacement in a second direction different from the first direction by exciting the B ₁₂ vibration; the (R, 1) vibration, the ((1, 1)) vibration, and the B ₁₂ The driving force take-out part is formed by switching between a periodic displacement in a third direction in which the first direction and the second direction are combined by exciting vibration, and forming the driving force extracting part. 6. The vibration actuator according to 6.