JPH1080160A - Vibrating actuator and its control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibrating actuator whose driving speed can be controlled from an ultralow-speed region up to an ultrahigh-speed region and which eliminates the generation of a speed irregularity as much as possible especially in an ultralow-speed drive and to provide its control method. SOLUTION: An ultrasonic actuator is provided with a vibrator 21 provided with a piezoelectric body 22a, for a torsional vibration, whose main body displays a column-shaped outer shape and which generates the torsional vibration vibrated to a direction contained in an edge 21a and with a piezoelectric body 22b, for a longitudinal vibration, which generates the longitudinal vibration vibrated to a direction at right angles to the edge 21a and with a moving element which is brought into press contact with the edge 21a and which generates a relative motion between itself and the vibrator 21. In the ultrasonic actuator, the piezoelectric body 22b for the longitudinal vibration is composed of two electromechanical conversion elements 22b-1, 22b-2 which convert electric energy into a mechanical displacement independently.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a vibration actuator and a control method thereof.

[0002]

2. Description of the Related Art Traveling wave type vibration actuators are reported, for example, in "Nikkei Mechanical, February 28, 1983". In brief, the vibration actuator generates a traveling wave of ultrasonic waves on the drive surface of the stator made of an elastic body by applying a two-phase drive signal. Then, the moving element that comes into pressure contact with the driving surface is frictionally driven by the elliptical motion at the traveling wave wavefront.

FIG. 13 is a perspective view showing an example of the structure of a vertical-torsional vibration type vibration actuator. Conventionally,
In this type of vibration actuator, the stator 101 is
An annular torsional vibration piezoelectric body 104 is interposed between two cylindrical vibrators 102 and 103, and
It is configured by disposing an annular longitudinal vibration piezoelectric body 105 above the vibrator 103. The piezoelectric body for torsional vibration 104 is polarized in the circumferential direction. Further, the piezoelectric body for longitudinal vibration 105 is polarized in the thickness direction. In addition, mover 1
Reference numeral 06 is arranged on the upper end surface side of the piezoelectric body 105 for longitudinal vibration.

The vibrators 102, 1 constituting the stator 101
03 and the piezoelectric bodies 104 and 105
7 is fixed by being screwed to a threaded portion provided on the outer surface of 7. Further, the moving element 106 is rotatably attached to the fixed shaft 107 via a ball bearing 108 mounted at the center. At the tip of the fixed shaft 107,
The nut 110 is screwed via the spring 109. The moving element 106 is fixed to the stator 10 by the spring force F of the spring 109.
1 is brought into pressure contact with the end face.

The torsional vibration piezoelectric body 104 and the longitudinal vibration piezoelectric body 105 are both driven by appropriately controlling the phase of the drive voltage of the same frequency oscillated from the oscillator 111 by the phase shifter 112. You.

The piezoelectric body 104 for torsional vibration is
6 provide a mechanical displacement for rotation about the fixed axis 107. On the other hand, the piezoelectric body 105 for longitudinal vibration is
The friction generated between the stator 101 and the moving element 106 is periodically changed in synchronization with the cycle of the torsional vibration by the piezoelectric body 104, so that the vibration generated in the stator 101 is
06 acts as a clutch that converts the movement in one direction.

FIG. 14 is an exploded perspective view showing the stator 101 constituting the vibration actuator shown in FIG. As described above, the torsional vibration piezoelectric body 104 needs to be polarized in the circumferential direction. Therefore, the torsional vibration piezoelectric body 104 divides the piezoelectric material once into about 6 to 8 fan-shaped small pieces as shown in FIG. 14 and polarizes each of the divided small pieces in the circumferential direction. It was configured by assembling again annularly. FIG.
Reference numeral 104a denotes an electrode for applying a drive voltage to the torsional vibration piezoelectric body 104.

[0008]

However, in the conventional vibration actuator configured as described above, it is extremely difficult to secure desired dimensional accuracy when assembling the torsional vibration piezoelectric body 104 in a ring shape. .

On the other hand, in FIG.
The cross-sectional area of each of the piezoelectric body 05 and the torsional vibration piezoelectric body 104 was substantially equal to or slightly smaller than the cross-sectional area of the stator 101. In addition, fixed shaft 1
07 for penetrating torsion in the center
04, it was necessary to make a hole in the center of the piezoelectric body 105 for longitudinal vibration. Therefore, the cross-sectional areas of the torsional vibration piezoelectric body 104 and the longitudinal vibration piezoelectric body 105 are further reduced, and it is difficult to increase the torque and the rotation of the vibration actuator.

[0010] In order to solve such a problem, the present applicant has already developed a modified mode degeneration that can be driven by high torque and high rotation, and that has a simple structure and is easy to manufacture. For example, Japanese Patent Application Nos. 6-180279 and 6-275022 propose a vibration actuator of the type.

FIG. 15 is a longitudinal sectional view showing a structural example of the vibration actuator 1 according to these proposals, and FIG.
FIG. 17A is a block diagram showing the control of the vibration actuator 1 of FIG. 15. FIG. 17A shows the vibrator 2 sandwiched between the semi-cylindrical elastic bodies 2a and 2b shown in FIG. FIG. 17 (b) shows the vibrator 2 shown in FIG.
It is the figure which looked at from the side. Further, FIG. 18 shows a vibration actuator 1 that generates an elliptical motion on the driving surface 2c by combining the longitudinal vibration and the torsional vibration generated in the vibrator 2.
FIG. 4 is an explanatory diagram showing the driving principle of FIG.

That is, in FIGS. 15 and 16, the vibrator 2 of the longitudinal-torsional vibration type vibration actuator 1 is
The piezoelectric members 3 and 4 which are electromechanical transducers that are excited by the drive signal and convert electric energy into mechanical displacement are joined to the piezoelectric members 3 and 4, and the piezoelectric members 3 and 4 are excited. As a result, primary longitudinal vibration and primary torsional vibration are generated, and hollow semi-cylindrical elastic bodies 2a and 2b that generate a driving force on the driving surface 2c that is the end face.

The elastic members 2a and 2b are elastic members having a shape in which a thick hollow cylinder is vertically divided into two. Elastic body 2a,
The piezoelectric bodies 3 and 4 are sandwiched between the divided surfaces 2b.
The piezoelectric bodies 3 and 4 are each composed of a total of four layers, two layers each. Two of the four layers of the piezoelectric body 3 are torsional vibration piezoelectric bodies using the piezoelectric constant d ₁₅ , and the remaining two layers of the piezoelectric body 4 are piezoelectric constants d ₃₁
Is a piezoelectric body for longitudinal vibration.

The elastic bodies 2a and 2b have through holes 2d and 2e at substantially the center in the height direction in parallel with the laminating direction of the piezoelectric bodies 3 and 4.
Is formed. The elastic bodies 2a and 2b are
By fixing the bolts 6a and 6b using d and 2e, the piezoelectric bodies 3 and 4 are sandwiched and screwed to the fixed shaft 5 inserted at the center in the axial direction.

The moving element 7 which is a relative moving member is provided with a moving element base material 7-1 and a sliding member 7 which is attached to an end face of the moving element base material 7-1 and comes into contact with the drive surface 2c of the vibrator 2. And 2. The movable element 7 is rotatably positioned and fixed to the fixed shaft 5 via a bearing 8 which is a positioning member fitted to an inner peripheral portion thereof.

The moving element 7 is urged toward the vibrator 2 by a disc spring 9a as a pressing member,
It is brought into pressure contact with the drive surface 2c. The fixed shaft 5 includes the elastic body 2
a, 2b penetrates the hollow portion formed in the axial direction,
The vibrator 2 composed of the elastic bodies 2a, 2b and the like is fixed and held, and the moving element 7 is positioned in the radial direction.
The fixed shaft 5 has a threaded portion at the upper end, and a nut 9b, which is a pressing force adjusting member for adjusting the pressing force of the disc spring 9a, is screwed.

Piezoelectric body for torsional vibration 3, Piezoelectric body for longitudinal vibration 4
As shown in FIG. 16, an oscillator 10 for oscillating a drive signal, a phase shifter 11 for distributing the output drive signal to a signal having a (1/4) λ phase difference, It comprises a T amplifier 13 for amplifying the drive signal input to the piezoelectric body 3, an L amplifying section 12 for amplifying the drive signal input to the longitudinal vibration piezoelectric body 4, and the like.

The control circuit 16 includes a detecting unit 14 for detecting torsional vibration, a control unit 15 for controlling a frequency and a voltage output from the oscillating unit 10 in accordance with a detection amount of the detecting unit 14, and the like. Consists of The detection unit 14 includes a piezoelectric body 14a that is attached to a side surface of the vibrator 2 and converts mechanical displacement into electric energy. Thus, by detecting the amount of displacement generated in the vibrator 2 due to torsion, the torsional displacement generated in the vibrator 2 is indirectly detected.

As shown in FIGS. 17 (a) and 17 (b), the piezoelectric members 3 and 4 are composed of two groups sandwiched between two elastic members 2a and 2b. Each group of the piezoelectric bodies 3 and 4 has four layers. Among the piezoelectric four layers of piezoelectric material 2 layer is composed of a piezoelectric element 3 using a piezoelectric constant d _15, whereas, the piezoelectric body of the remaining two layers composed of a piezoelectric body 4 using a piezoelectric constant d _31.

The piezoelectric element 3 is a piezoelectric constant d _15, the elastic body 2a, the shear displacement is generated with respect to the longitudinal direction of 2b. In FIG. 17A, the piezoelectric bodies 3 are arranged on the two divided surfaces of the elastic bodies 2a and 2b such that the shear deformation alternates in the circumferential direction with respect to the near side and the opposite direction.

By disposing the piezoelectric bodies 3 in this manner, when each of them is subjected to shear deformation, a torsional displacement is generated in the vibrator 2, and the end face of the vibrator 2 is twisted. On the other hand, the piezoelectric body 4 is using a piezoelectric constant d _31, the elastic body 2a, to generate the elastic displacement with respect to the longitudinal direction of 2b. The four piezoelectric members 4 for longitudinal vibration are all arranged such that when a certain potential is applied, displacement occurs in the same direction.

[0022] As described above, the vibration piezoelectric member 3 torsional using a piezoelectric constant d _15, with arranging the longitudinal vibration piezoelectric member 4 using a piezoelectric constant d _31, the torsional vibration piezoelectric member 3 , A torsional motion is generated in the vibrator 2 accordingly. On the other hand, when a sinusoidal voltage is applied to the piezoelectric body 4 for longitudinal vibration, the vibrator 2 expands and contracts accordingly.

In such a vibration actuator 1, as shown in FIG.
When a drive signal is applied from the amplifying unit 13 and the L amplifying unit 12 to the torsional vibration piezoelectric body 3 and the longitudinal vibration piezoelectric body 4, the torsional vibration piezoelectric body 3 and the longitudinal vibration piezoelectric body 4 respectively become When the vibrator 2 is excited, torsional vibration and longitudinal vibration are generated.

That is, as shown in FIG. 18, when the phase difference between the period of the torsional vibration T and the period of the longitudinal vibration (expanding / contracting movement) L is set to be shifted by (１ ／) λ (λ: wavelength), An elliptical motion occurs at a fixed point A on the drive surface 2c of the vibrator 2.

In FIG. 18, the frequency of the voltage applied during driving is f, and the angular frequency at this time is ω (= 2πf).
Then, at the time of t = (6/4) · (π / ω), the displacement of the torsional vibration T is maximum on the left side. On the other hand, the longitudinal vibration L
Is zero. In this state, the moving element is in a state of being pressed by the pressing member to the driving surface 2 c of the vibrator 2.

From this state, t = (7/4) · (π /
ω) to 0 to (2/4) · (π / ω), the torsional vibration T is displaced from the maximum on the left to the maximum on the right. On the other hand, the longitudinal vibration L is displaced from zero to the upper maximum and returns to zero again. Therefore, the driving surface 2c of the vibrator 2 contacts the end face of the moving element and rotates to the right while pushing the moving element, and the rotation drives the moving element to the right.

Next, t = (2/4) · (π / ω)-(6
/ 4) · (π / ω), the torsional vibration T is displaced from the maximum on the right to the maximum on the left. On the other hand, the longitudinal vibration L is displaced from zero to the maximum below and returns to zero again. Accordingly, the driving surface 2c of the vibrator 2 rotates leftward while moving away from the moving element, and the moving element is not driven. At this time, the moving element is pressed toward the drive surface 2c side of the vibrator 2 by the pressing member (not shown in FIG. 18) as described above. Cannot follow shrinkage.

When the resonance frequencies of the torsional vibration and the longitudinal vibration generated in this way are substantially matched, the torsional vibration and the longitudinal vibration are simultaneously generated (this state is referred to as "degeneration").
That. ), An elliptical motion, which is a combination of torsional vibration and longitudinal vibration, is generated on the driving surface 2c of the vibrator 2, and a driving force is generated.
The mover is driven to rotate.

Conventionally, when controlling the driving speed of a traveling wave type vibration actuator, as shown in "Nikkei Mechanical, February 28, 1983, page 46, FIG. 6", The voltage value of the drive signal input to each piezoelectric body is changed at the same rate. That is, unless the input voltage values of the two-phase drive signals are simultaneously controlled to the same value,
This is because the waveform of the traveling wave is disturbed, and no elliptical motion occurs on the driving surface 2c of the vibrator 2, which makes it difficult to drive the moving element.

That is, in the conventional traveling wave type vibration actuator, when the voltage of the drive signal is changed at the same rate of change, the magnitude of the elliptical motion generated on the drive surface of the vibrator according to the voltage of the drive signal is reduced. Change analogously.
Thereby, the driving speed and driving force of the moving element can be changed.

As described above, in the traveling wave type vibration actuator, the vibrator and the moving element are always in point or linear contact with each other at the wave front of the traveling wave. Therefore, the driving force can be transmitted from the vibrator to the moving element even when the elliptical motion becomes small. Therefore, by simultaneously lowering the two-phase drive voltages at the same rate of change, the drive speed can be reduced to a low speed, and the drive speed unevenness is unlikely to occur even at a low speed.

On the other hand, in the modified mode degenerate type vibration actuator shown in FIGS. 15 to 18, displacement in the drive direction is generated by the first phase drive signal, as described above.
The displacement in the direction perpendicular to the drive direction is generated by the drive signal of the second phase, and an elliptic motion is generated on the drive surface by the combination thereof.
That is, the first-phase drive signal is involved in driving of the moving element (relative motion between the vibrator and the relative motion member), and the second-phase driving signal is transmitted to the moving element (power transmission between the vibrator and the relative motion member). Clutch mechanism between the member).

Therefore, when controlling the driving speed of the modified mode degenerate type vibration actuator, the frequency of the driving signal output from the oscillation unit 10 is controlled in the same manner as in the case of the conventional traveling wave type vibration actuator, and the L amplification is performed. When the two-phase driving voltages output from the unit 12 and the T amplifying unit 13 are reduced at the same rate of change, the elliptical motion is correspondingly reduced accordingly. As a result, the elliptic motion component in the driving direction is also reduced, and the driving speed is reduced.

However, since the drive voltage is reduced in both phases, the elliptical motion component in the direction perpendicular to the drive direction is also reduced. Therefore, if the magnitude of the elliptical motion component in the vertical direction is smaller than the surface roughness of the drive surface, the clutch mechanism between the vibrator and the relative motion member becomes insufficient.
For this reason, in the modified mode degenerate type vibration actuator, it is difficult to perform low-speed driving, and the operation of the clutch mechanism is insufficient due to the reduction in speed, so that there is a problem that speed unevenness during low-speed driving is likely to occur. Was.

On the other hand, contrary to the case of the low-speed driving, when the driving voltage is increased in both phases to perform the high-speed driving, not only the elliptic motion component in the driving direction but also the elliptical motion component in the direction perpendicular to the driving direction is obtained. Also grows similarly. Therefore, when the magnitude of the elliptical motion component in the direction perpendicular to the driving direction is larger than the appropriate range, the clutch mechanism becomes insufficient and the driving efficiency is reduced. For this reason, there is a limit value at which high-speed driving can be stably performed even in a modified mode degenerate type vibration actuator. Therefore, there is also a problem that speed unevenness is likely to occur even in an ultra-high speed region exceeding the limit value.

An object of the present invention is to solve the problem of such a modified mode degenerate type vibration actuator, and more specifically, it is possible to control the driving speed from a very low speed range to a very high speed range. In particular, it is an object of the present invention to provide a vibration actuator and a control method thereof that minimize occurrence of speed unevenness particularly at the time of ultra-low speed driving.

[0037]

According to a first aspect of the present invention, there is provided a first electromechanical converter for generating a first vibration in which a main body has a columnar outer shape and vibrates in a plane parallel to an end surface of the main body. First
A vibration actuator comprising: a vibrator including a second electromechanical transducer that generates a second vibration that vibrates in a direction different from the vibration direction of the vibration; and a relative motion member that performs a relative motion between the vibrator and the vibrator. , The second electromechanical converter is constituted by a plurality of independent electromechanical converters for converting electric energy into mechanical displacement.

According to a second aspect of the present invention, in the vibration actuator according to the first aspect, the plurality of electromechanical conversion parts are formed by an integrated electromechanical conversion element and a plurality of divided electrodes mounted on the surface thereof. Alternatively, it is characterized by being constituted by a plurality of divided electromechanical transducers and a plurality of electrodes mounted on their surfaces.

The third aspect of the present invention is the first or second aspect.
The first vibration is a torsional vibration about the axis of the vibrator, and the second vibration is a longitudinal vibration about the axial direction of the vibrator.

The invention according to claim 4 is the invention according to claims 1 to 3.
In the vibration actuator according to any one of the above, the first electromechanical conversion unit includes:
One or two are formed at positions including the nodal position of the vibration, and one second electromechanical transducer is formed at a position including the nodal position of the second vibration generated in the vibrator. I do.

According to a fifth aspect of the present invention, there is provided a first electromechanical converter for generating a first vibration and a second electromechanical converter for generating a second vibration that vibrates in a direction different from the direction of vibration of the first vibration. A method of controlling a vibration actuator having a vibrator and a relative motion member that performs relative motion between the vibrator, wherein the second electromechanical converter is divided into a plurality of regions, and a drive signal is provided for each region. And the speed of the relative movement is controlled by individually controlling each drive signal.

According to a sixth aspect of the present invention, in the method of controlling a vibration actuator according to the fifth aspect, the voltage of the drive signal applied to the first electromechanical converter is reduced and the voltage of the second electromechanical converter is reduced. The speed of the relative movement is reduced by increasing the voltage of at least one of the plurality of drive signals applied to each area.

According to a seventh aspect of the present invention, in the method for controlling a vibration actuator according to the fifth aspect, the voltage of the drive signal applied to the first electromechanical converter is increased and the voltage of the second electromechanical converter is increased. It is characterized in that the speed of the relative movement is increased by reducing the voltage of at least one of the plurality of drive signals applied to each area.

The invention of claim 8 is the invention of claims 5 to 7.
In the method for controlling a vibration actuator according to any one of the above, the driving signal applied to the first electromechanical conversion unit and the plurality of driving signals applied to each region of the second electromechanical conversion unit The speed of the relative movement is controlled by changing the frequency of at least one of the drive signals.

According to a ninth aspect of the present invention, in the control method of the vibration actuator according to the eighth aspect, the frequency of the drive signal is reduced and the voltage of the drive signal applied to the first electromechanical converter is increased. The speed of the relative motion is increased by reducing at least one voltage of a plurality of drive signals applied to each area of the second electromechanical converter.

According to a tenth aspect of the present invention, there is provided a first electromechanical converter for generating a first vibration and a second electromechanical converter for generating a second vibration which vibrates in a direction different from the direction of vibration of the first vibration. A vibrator, a relative motion member performing relative motion between the vibrator, and a vibration actuator having a drive circuit for applying a drive signal to the first electromechanical converter and the second electromechanical converter, At least one of the first electromechanical converter and the second electromechanical converter has a plurality of electromechanical converters for converting electrical energy into mechanical displacement, and the drive circuit is configured to control the plurality of electromechanical converters. It is characterized in that a difference is generated in the amount of mechanical displacement.

The eleventh aspect of the present invention includes a first electromechanical converter for generating a first vibration and a second electromechanical converter for generating a second vibration that vibrates in a direction different from the direction of the first vibration. A method for controlling a vibration actuator having a vibrator and a relative motion member that performs relative motion between the vibrator and the vibrator, wherein at least one of a first electromechanical converter and a second electromechanical converter is used. In addition, an electromechanical converter for converting electric energy into mechanical displacement is divided into a plurality of regions, and a difference is generated in the amount of mechanical displacement between the respective regions.

In the first to ninth aspects of the present invention, the “first electromechanical converter” and the “second electromechanical converter” are an electromechanical transducer for converting electric energy into mechanical displacement, an electrode, And a component of the vibrator that converts electrical energy into mechanical displacement.

In the first to ninth aspects of the present invention, the “electromechanical converter” means each of a plurality of second electromechanical converters, which are components of the second electromechanical converter. .

[0050]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the embodiments, an example of an ultrasonic actuator that uses an ultrasonic vibration region as a vibration actuator will be described.

FIG. 1 is a longitudinal sectional view showing an ultrasonic actuator 20 according to the first embodiment of the present invention. The vibrator 21 includes piezoelectric bodies 22a and 22b, which are electromechanical transducers excited by a drive signal, and these piezoelectric bodies 22a and 22b.
When the piezoelectric bodies 22a and 22b are joined and the piezoelectric bodies 22a and 22b are excited to generate a secondary torsional vibration and a primary longitudinal vibration, a hollow cylindrical outer shape that generates a driving force on the driving surface 21a as an end surface is formed. The elastic body 23 is provided.

The elastic body 23 is made of a metal material having a large resonance sharpness, such as steel, stainless steel, phosphor bronze, and elinvar. Three small-diameter portions 23a, 23b, and 23c are formed in an annular shape on the outer peripheral surface of the elastic body 23, and are divided into these small-diameter portions 23a to 23c to form four large-diameter portions 23A and 23B. , 23C, 23D
Is formed.

The elastic body 23 is obtained by assembling two semi-elastic bodies 24a and 24b obtained by dividing a thick hollow cylindrical body vertically into two substantially at the center axis thereof, again into a cylindrical shape. can get.

As will be described later, two layers of the piezoelectric members 22a and 22b and the electrodes 2
5a and 25b are held in a sandwiched state. The piezoelectric body 22a is a torsional vibration piezoelectric body that generates torsional vibration in the elastic body 23. This torsional vibration piezoelectric body 22a
Is disposed at a node position on the drive surface 21a side of the generated torsional vibration. On the other hand, the piezoelectric body 22b is a piezoelectric body for longitudinal vibration that generates longitudinal vibration (stretching vibration) in the elastic body 23. The piezoelectric body for vertical vibration 22b is arranged at a node position of the generated vertical vibration. Here, the reason why the small-diameter portions 23a to 23c are formed in the elastic body 23 is that the resonance frequency of the longitudinal primary vibration generated in the elastic body 23 and the resonance frequency of the torsional secondary vibration are substantially matched, and the vibrator is formed. This is for generating an elliptical motion on the drive surface 21a of the motor 21.

The through holes 2 are formed in the elastic body 23 in a direction perpendicular to the central axis (a direction parallel to a laminating direction of piezoelectric bodies described later).
6a and 26b are provided. The elastic body 23 having the semi-elastic bodies 24a and 24b is provided with the bolt 2 in the through holes 26a and 26b.
By inserting the nuts 7a and 27b and screwing the nuts 28a and 28b, the nuts 28a and 28b are fastened and fixed with the piezoelectric bodies 22a and 22b sandwiched therebetween.

A through hole 29 is provided in the small diameter portion 23a formed in the elastic body 23, and a fixing pin 30 which passes through the through hole 29 and also passes through a fixed shaft 31 which will be described later.
Thereby, the elastic body 23 is fixed to the fixed shaft 31.

The moving element 32 includes a moving element base material 32a made of stainless steel, a copper alloy, an aluminum alloy or the like, and a driving surface 21 of the vibrator 21 attached to an end face of the moving element base material 32a.
and a sliding member 32b mainly made of a polymer material or the like that comes into contact with the sliding member 32a.

A bearing 33a, which is a positioning member, is fitted on the inner peripheral portion of the movable member 32, and is positioned rotatably with respect to the fixed shaft 31 via the bearing 33a. An output take-out gear 32c is formed in an annular shape on the outer peripheral surface of the mover base material 32a, and the output is transmitted to a gear of a driven body (not shown).

The moving element 32 is brought into pressure contact with the drive surface 21a of the elastic body 23 by a disc spring 33b (which may be a spring or a leaf spring) as a pressure member. The fixed shaft 31 penetrates a hollow portion 34 formed in the axial direction of the elastic body 23, and fixes the elastic body 23 to the fixing pin 30.
And positions the movable element 32 so as to be rotatable in the radial direction. The fixed shaft 31 has a screw portion 31a formed near the distal end thereof.
A nut 35, which is a pressing force adjusting member for adjusting the pressing force of the disc spring 33b, is screwed to the nut.

Grooves 36 are provided near both ends of the fixed shaft 31.
a and 36b are formed, and are fixed to the device fixing portion by set screws when mounted on the device, and are prevented from rotating. FIG. 2 shows a vibrating piezoelectric body 22 mounted on the vibrator 21.
It is explanatory drawing which shows the arrangement of a and 22b with an example of the longitudinal vibration mode and the torsional vibration mode which generate | occur | produce in the vibrator 21.

As described above, the elastic body 23 is a semi-elastic body 24 obtained by vertically dividing a thick-walled cylinder having four large-diameter portions 23A to 23D and three small-diameter portions 23a to 23c into two.
a, 24b is an elastic member obtained by assembling again into a columnar shape. The split surface of the elastic body 23 holds the two layers of the piezoelectric bodies 22a and 22b and the electrodes 25a and 25b in a state of being sandwiched therebetween.

The small-diameter portions 23a and 23c are connected to nodes (positions A and B in FIG. 2B) of torsional vibration generated in the elastic body 23.
C). Further, the small diameter portion 23b is
Nodal part of longitudinal vibration generated at position (position B in FIG. 2 (b))
Placed in The torsional vibration piezoelectric body 22a is disposed at a position including a position A across the node on the drive surface 21a side of the torsional vibration, while the longitudinal vibration piezoelectric body 22b is positioned at a position B across the longitudinal vibration node. Is arranged at a position including.

The torsional vibration piezoelectric body 22a has a piezoelectric constant d
It is composed of a piezoelectric material using ₁₅ , and when a frequency voltage is applied, it generates shear deformation according to the direction of the applied voltage,
As a result, a secondary torsional vibration that oscillates in a direction included in the driving surface 21a that is the end face of the vibrator 21 is generated. In the present embodiment, the secondary torsional vibration is the first torsional vibration in the present invention.
The first electromechanical converter is a vibration range of the vibrator 21 in which the piezoelectric body 22a is mounted.

The torsional vibration piezoelectric element 22a is composed of two torsional vibration piezoelectric elements 22a on the front side and two torsional vibration piezoelectric elements 22a on the other side. The torsional vibration piezoelectric body 22a on the near side and the torsional vibration piezoelectric body 2 on the other side
2a is arranged such that the shearing deformations that occur are in opposite directions when a voltage in the same direction is applied, and a torsional displacement occurs in the vibrator 21 in a certain direction. In the present embodiment, the primary longitudinal vibration is the second vibration in the present invention, and the range of the vibrator 21 where the piezoelectric body 22b is mounted is the second electromechanical converter.

For example, as shown in FIG. 2B, when both the two torsional vibration piezoelectric bodies 22a on the front side and the two torsional vibration piezoelectric bodies 22a on the other side are sheared,
The drive surface 21a is twisted in the rotation direction indicated by the arrow in FIG. When a voltage in the opposite direction is applied, shearing deformation in the opposite direction is generated, and the driving surface 21a is turned off as shown in FIG.
It is twisted in the direction opposite to the direction indicated by the arrow in FIG.

[0066] longitudinal vibration piezoelectric element 22b is constituted by a piezoelectric element using a piezoelectric constant d _31, the expansion deformation occurs in response to the direction of the voltage-frequency voltage is applied to be applied, it is thereby vertically vibrating Occur.

Similarly to the torsional vibration piezoelectric body 22a, the two longitudinal vibration piezoelectric bodies 22b are also provided.
b and two longitudinal vibration piezoelectric members 22b on the other side. When voltages in the same direction are applied to these piezoelectric members for vertical vibration 22b, they are vertically deformed in the same direction. By arranging the piezoelectric bodies for vertical vibration 22b in this manner, a longitudinal vibration is generated in the vibrator 21.

FIG. 3 is a perspective view showing the vibrator 21 constituting the ultrasonic actuator 20 of the first embodiment in an exploded state together with a control block diagram. The elastic body 23 is a thick wall having three small diameter portions 23a to 23c formed on the outer peripheral surface and four large diameter portions 23A to 23D formed by being divided by these small diameter portions 23a to 23c. Semi-elastic body 2 obtained by vertically dividing a cylindrical body into two
This is an elastic member obtained by combining 4a and 24b again in a columnar shape.

Two layers of the piezoelectric members 22a and 22b and the electrodes 25a and 25b are sandwiched between the two divided surfaces of the elastic member 23. The small diameter portion 23b is arranged at a node of the longitudinal vibration. The torsional vibration piezoelectric body 22a is arranged so as to straddle a node on the driving surface side of torsional vibration, and the longitudinal vibration piezoelectric body 22b is arranged to straddle a longitudinal vibration node.

The torsional vibration piezoelectric body 22a has a piezoelectric constant d
_When a frequency voltage is applied, a shear deformation is generated in accordance with the direction of the voltage, so that the vibrator 21 generates torsional vibration about the vibrator axis.

[0071] longitudinal vibration piezoelectric element 22b is constituted by a piezoelectric element using a piezoelectric constant d _31, the frequency voltage is applied to generate the stretching deformation in accordance with the direction of the voltage, thereby vibrating the vibrator 21 Longitudinal vibration occurs in the slave axis direction.

In the ultrasonic actuator 20 of the present embodiment, the torsional vibration detecting piezoelectric body 37a is
And a longitudinal vibration detecting piezoelectric body 37b is provided to detect the longitudinal vibration of the vibrator 21.

The torsional vibration detecting piezoelectric member 37a, the torsional vibration detecting piezoelectric member 22a, the longitudinal vibration piezoelectric member 22b, and the longitudinal vibration detecting piezoelectric member 37b are arranged in this order from the driving surface 21a side to the non-driving surface side. Are arranged on the same plane (division surface of the elastic body 23) for each layer.

Further, in the ultrasonic actuator 20 of the present embodiment, the longitudinal vibration piezoelectric body 22b is constituted by the first longitudinal vibration piezoelectric body 22b-1 and the second longitudinal vibration piezoelectric body 22b-2.

The torsional vibration piezoelectric body 22a is disposed so as to straddle the nodal position A of the torsional vibration. Further, the first piezoelectric member for longitudinal vibration 22b-1 is disposed so as to straddle the node position B of the longitudinal vibration, and the second piezoelectric member for longitudinal vibration 22b-2 is disposed so as to straddle the node position C of the torsional vibration. Is done.

The electrodes 25a and 25b are respectively composed of a two-layer torsional vibration piezoelectric body 22a and a torsional vibration detecting piezoelectric body 37a.
a, which is disposed between the first longitudinal vibration piezoelectric body 22b-1, the second longitudinal vibration piezoelectric body 22b-2, and the longitudinal vibration detecting piezoelectric body 37b, and has two layers of longitudinal vibration piezoelectric bodies 22b-1. , 22b-
It is configured such that a drive voltage can be simultaneously applied to the two and two layers of torsional vibration piezoelectric bodies 22a.

The voltage is also detected from the torsional vibration detecting piezoelectric element 37a and the longitudinal vibration detecting piezoelectric element 37b. In this way, the vibrator 21
It is composed of a first piezoelectric member for longitudinal vibration 22b-1 and a second piezoelectric member for longitudinal vibration 22b-2 which constitute two electromechanical converters for converting electric energy into mechanical displacement independently of each other.

In this embodiment, the two electromechanical converters are divided into two piezoelectric bodies 22b-1, 22b-2 and electrodes 25b-1, 25b- mounted on their surfaces.
2, the piezoelectric body 22b is integrated without being divided, and electrodes 25b-1, 25b- are formed on the surface of the piezoelectric body 22b.
2, two electromechanical converters may be configured. By integrating the piezoelectric body 22b, the number of component parts is reduced, and the assemblability is improved.

The elastic members 24a and 24b and each piezoelectric member 2
The electrodes 2a, 22b-1, 22b-2, 37a, 37b and the electrodes 25a, 25b are adhered and joined. On the other hand, the drive circuit 40 includes an oscillator 41 for generating a drive signal, a phase shifter 42 for distributing the drive signal to a signal having a phase difference of about (１ ／) λ, and an input to a torsional vibration piezoelectric body 22a. Voltage amplifying section 43 for amplifying a driving signal (hereinafter, referred to as a “T-phase driving signal”), and a first vertical vibration piezoelectric body 22b-1.
And an L1 voltage amplifying unit 44-1 for amplifying a drive signal (hereinafter, referred to as a "first L-phase drive signal"), and a drive signal (hereinafter, referred to as a "first L-phase drive signal") input to the second longitudinal vibration piezoelectric body 22b-2. 2L-phase drive signal ”).

The control circuit 45 includes a speed setting section 46 for setting a speed, a speed detecting section 47 for detecting a speed, and a speed value and a speed detecting section 47 set by the speed setting section 46.
A speed command unit 48 for instructing the speed to the control unit so as to eliminate the difference by comparing the detected speed value with the speed value, and a T-phase control signal voltage receiving the signal from the speed command unit 48 to control the T-phase drive signal voltage.
A voltage control unit 49 and an L controlling the second L-phase drive signal voltage;
And a two-voltage control unit 50.

The speed may be detected by monitoring the output from the torsional vibration detecting piezoelectric body 37a in FIG. 3 and converting the detected value into a speed value, or by directly reading the output from the encoder. .

To the vibrator 21 configured as described above, two drive signals having a phase difference of about (1/4) λ are applied to the piezoelectric body 22a for torsional vibration and the piezoelectric body 22b for longitudinal vibration, respectively.
1 and 22b-2, the phases of the torsional vibration and the longitudinal vibration generated in the vibrator 21 are shifted by 90 degrees, and the elliptical motion obtained by combining these vibrations becomes a driving surface 21 of the vibrator 21.
a.

FIG. 4 is an explanatory diagram showing, over time, generation of an elliptical motion on the drive surface 21a of the vibrator 21 by combining such torsional vibration and longitudinal vibration generated in the vibrator 21. .

As shown in FIG. 4, when the phase difference between the period of the torsional vibration and the period of the longitudinal vibration is set to be shifted by about (1/4) λ (λ: wavelength), the fixed point on the driving surface 21a Generates an elliptical motion. Here, when the frequency of the drive signal is set to a value close to the natural frequency of the longitudinal primary vibration mode and the natural frequency of the torsional secondary vibration mode, both the torsional vibration amplitude and the longitudinal vibration amplitude increase, and Elliptical motion can be obtained.

Assuming that the angular velocity of the moving element 32 is ω, t = 0
At this point, the displacement of the torsional vibration is the largest on the left side, and the displacement of the longitudinal vibration is zero. In this state, the moving element (not shown) comes into pressure contact with the driving surface 21a of the vibrator 21 by the pressing member.

From this state, t = 0 to (4/4) · (π
/ Ω), the torsional vibration is displaced from the maximum on the left to the maximum on the right, and the longitudinal vibration is displaced from zero to the upper maximum and returns to zero again. Therefore, the driving surface 21a of the vibrator 21 rotates rightward while pressing the moving element, and the moving element is driven.

Next, from t = (4/4) · (π / ω) to 0, the torsional vibration is displaced from the maximum on the right to the maximum on the left, and the longitudinal vibration is reduced from zero to the maximum on the lower side. It displaces and returns to zero again.
Therefore, since the driving surface 21a of the vibrator 21 rotates leftward while moving away from the movable element, the movable element is not driven. At this time, the moving element is pressed by the pressing member, but cannot follow the contraction of the vibrator 21 because the natural frequency of the pressing member is lower than the ultrasonic vibration range.

FIG. 5 shows that in the first embodiment, the T-phase drive signal voltage VT and the first L
Phase drive signal voltage VL1 and second L-phase drive signal voltage VL2
It is a graph which shows an example of each control.

In the present embodiment, briefly, the first drive signal voltage (T-phase drive signal voltage) applied to the torsional vibration piezoelectric body 22a constituting the first electromechanical converter and the second electrical signal Two first longitudinal vibration piezoelectric members 22 forming a mechanical conversion unit
b-1, the first L-phase drive signal voltage VL1 and the second L-phase drive signal voltage V applied to the second vertical vibration piezoelectric body 22b-2.
By controlling the second driving signal voltage (L-phase driving signal voltage) composed of L2, the relative movement speed between the vibrator 21 and the moving element 32 is controlled.

That is, when the speed of the moving element 32 is changed from high speed to low speed (for example, from normal operation to low speed operation), the T-phase drive signal voltage VT is gradually reduced. Also,
The drive frequency is kept constant regardless of the rotation speed. on the other hand,
The first L-phase drive signal voltage VL1 is also kept constant irrespective of the rotation speed, the second L-phase drive signal voltage VL2 is set to zero up to a certain predetermined rotation speed, and is increased stepwise when the rotation speed falls below the predetermined rotation speed. In the present embodiment, control is performed to reduce the first drive signal voltage (T-phase drive signal voltage) and increase at least one of the two second drive signal voltages (L-phase drive signal voltage). Even if the torsional vibration amplitude is reduced, the longitudinal vibration amplitude, which is a clutch component, can be sufficiently ensured. Therefore, it is possible to eliminate the occurrence of rotation unevenness during low-speed rotation.

In this embodiment, at the time of low-speed rotation, at least one of the piezoelectric members for longitudinal vibration 22b-1 and 22b-2 is applied at a high voltage to excite the longitudinal vibration, so that power consumption is correspondingly increased. However, since the voltage applied to the torsional vibration piezoelectric body 22a is reduced, the power consumption for exciting the torsional vibration is reduced accordingly. As a result, the increase and decrease in power consumption cancel each other out, so that the relative movement speed can be reduced without increasing the overall power consumption. In other words, by reducing the rotation speed, the decrease in power consumption due to torsional vibration excitation is allocated to the increase in power consumption during longitudinal vibration excitation.

FIG. 6 is an explanatory diagram showing control of the T-phase drive signal voltage. The T-phase drive signal voltage control unit is configured by a multiplexer or the like, and can select a signal from the speed command unit. M depending on the selected signal
Switching elements Q1 such as OS field effect transistors
It is configured so that Q8 can be turned on and off.

The resistors Rf1 to Rf8 having different resistance values are connected in parallel to the feedback section of the operational amplifier. Each resistor is connected to a switching element Q1-Q8 connected in series.
Is turned on by a control signal from a T-phase drive signal voltage control unit which is a control signal generation unit, so that the amplification amount of the operational amplifier can be determined. As a result, the driving signal from the phase shifter is amplified, and the T-phase electrode 25 of the vibrator 21 is amplified.
is input to a.

A case in which the T-phase drive signal voltage is changed will be described with reference to FIG. First, the case where the voltage is reduced will be described. In response to the instruction from the speed command unit, the T-phase drive signal voltage control unit turns on the switching element whose amplification factor decreases and turns off the other switching elements. Thus, the voltage input to the vibrator 21 decreases.

Conversely, a case where the voltage is increased will be described.
In response to an instruction from the speed command unit, the T-phase drive signal voltage control unit turns on a switching element having a large amplification factor and turns off other switching elements. Thereby, the voltage input to the vibrator 21 increases.

In the present embodiment, in order to make the description easy to understand, the digital signal from the A / D conversion unit is set to 8 bits, and the switching element and the resistance Rf are set to 8 bits.
It was made into pieces. However, the digital signal from the A / D conversion unit is set to 4 bits and the switching element and the resistor Rf
May be four in each case. Further, the digital signal from the A / D converter may be 16 bits, and the number of switching elements and the number of resistors Rf may be 16 respectively, or may be more. The greater the number of bits, the number of switching elements, and the number of resistors, the finer the control that can be performed.

FIG. 7 is an explanatory diagram showing control of the second L-phase drive signal voltage VL2. The second L-phase drive signal voltage control unit is also configured from a kind of multiplexer,
A signal from the speed command section can be selected, and the switching element Q1 such as a MOS field effect transistor can be turned on / off by the signal.

When the rotation speed of the moving element 32 is higher than a predetermined rotation speed, the switching element Q1 is turned off.
By turning off the switching element Q1, the second L-phase drive signal voltage becomes zero. When the rotation speed is lower than a predetermined rotation speed, the switching element Q1 is turned on. By turning on the switching element Q1,
The second L-phase drive signal voltage can be applied with a predetermined voltage.

In the present embodiment, the second L-phase drive signal voltage is applied in a stepwise manner when the speed becomes equal to or lower than the predetermined rotation speed. You may make it increase.

(Second Embodiment) FIG. 8 is a perspective view showing an oscillator 51 constituting an ultrasonic actuator according to a second embodiment in an exploded state together with a control block diagram. In addition,
In the following description of the embodiment, only portions different from the first embodiment will be described, and common portions will be denoted by the same reference numerals in the drawings, and redundant description will be omitted.

The vibrator 51 of the present embodiment differs from the first embodiment in a control circuit 45-1. That is, the control circuit 45-1 includes a speed setting unit 46 for setting a speed,
A speed detecting unit 47 for detecting the speed, and a speed for instructing the speed to the control unit 40 so as to eliminate the difference by comparing the speed value set by the speed setting unit 46 with the speed value detected by the speed detecting unit 47. A driving frequency control unit 52 that receives a signal from the speed commanding unit 48 and controls a driving frequency;
T-phase drive signal voltage controller 49 for controlling phase drive signal voltage
And a first L-phase drive signal voltage controller 50-1 for controlling the first L-phase drive signal voltage, and a second L-phase drive signal voltage controller 50-2 for controlling the second L-phase drive signal voltage.

The speed can be detected by monitoring the output from the torsional vibration detecting piezoelectric body in FIG. 3 and converting the detected value into a speed value, or by directly reading the output from the encoder. .

The drive circuit 40 includes an oscillator 41 for generating a drive signal and a drive signal for generating a drive signal of about (１ ／) λ.
A phase shifter 42 for dividing the signal into a signal having a phase difference, a T voltage amplifying unit 43 for amplifying a drive signal input to the torsional vibration piezoelectric body 22a, and a driving input to the first longitudinal vibration piezoelectric body 22b-1 An L1 drive signal voltage amplifier 44-1 for amplifying a signal,
An L2 drive signal voltage amplifying unit 44-2 for amplifying a drive signal input to the second vertical vibration piezoelectric body 22b-2.

The ultrasonic actuator 51 of the second embodiment thus configured is supplied with two drive signals having a phase difference of about (1/4) λ, respectively, to the first piezoelectric body 22b for longitudinal vibration.
-1, when input to the second piezoelectric body for longitudinal vibration 22b-2 and the piezoelectric body for torsional vibration 22a, the phases of the longitudinal vibration and the torsional vibration generated in the vibrator 21 are shifted by 90 degrees,
An elliptical motion combining these two types of vibrations is generated on the driving surface 21a of the vibrator 21.

FIG. 9 shows a drive frequency, a T-phase drive signal voltage VT, a first L-phase drive signal voltage VL1, and a second L-phase drive signal voltage according to a speed command of the moving element 32 according to the second embodiment of the present invention. FIG. 4 is an explanatory diagram showing control of VL2.

In the present embodiment, in brief, the first drive signal voltage (T-phase drive signal voltage) applied to the torsional vibration piezoelectric body constituting the first electromechanical converter and the second By controlling the two L-phase drive signal voltages VL1 and the second L-phase drive signal voltage VL2 that constitute the conversion unit with the L-phase drive signal voltage applied independently, the vibrator 21 and the mover 32 are controlled. To control the relative speed of movement between

That is, when the speed of the moving element 32 is changed from high speed to low speed (for example, from normal driving to low speed driving), in this embodiment, the driving frequency is gradually increased, and
The phase drive signal voltage VT is gradually reduced, the first L-phase drive signal voltage VL1 is kept unchanged, and the second L-phase drive signal voltage VL2 is gradually increased from 0.

Generally, it is difficult to excite a piezoelectric body unless a voltage of a certain magnitude is applied. Therefore, even in a state where the drive signal voltage of the T phase is higher than a value at which the drive signal voltage can be excited, it is possible to reduce the drive direction component of the elliptical motion generated on the drive surface 21a of the vibrator 21 by increasing the drive frequency. Can be.

On the other hand, in the present embodiment, since the driving frequency is increased, the pressing direction component of the elliptical motion is similarly reduced by the same amount. However, this reduction is achieved by increasing the second L-phase driving signal voltage. , Can be maintained at or above the required minimum value.

Since the driving frequency is close to the resonance point near the maximum rotational speed of the moving element, the pressing direction component of the elliptical motion is obtained only by applying the first L-phase driving signal voltage to the first L-phase. be able to. Therefore, the second L-phase drive signal voltage is set to zero, thereby making it possible to suppress power consumption near the maximum rotation speed.

FIG. 11 is an explanatory diagram showing a procedure for determining the drive frequency fmax at the maximum rotation speed Nmax and the drive frequency fmin at the minimum rotation speed Nmin. First, a drive signal is actually input, and the maximum rotation speed Nm
The drive frequency fmax at which ax is obtained is set as the drive frequency at the maximum rotation speed. In the driving frequency fmax, the impedance of the terminal to the torsional vibration piezoelectric body 22a at the actual voltage is between the maximum value and the minimum value.

Next, the piezoelectric body 2 for torsional vibration of the vibrator 21
The impedance at the actual voltage of the terminal to the terminal 2a is measured, and the point at which this impedance reaches a maximum value is defined as the drive frequency fmin at the minimum rotation speed Nmin, and the drive frequency region is defined by the two drive frequencies fmax and fmin. The value must be between. By setting the driving frequency region in this way, the power consumption of the torsional vibration excitation at the minimum rotation speed Nmin can be suppressed.

As described above, according to the present embodiment, the first drive signal input to the torsional vibration piezoelectric body 22a forming the first electromechanical converter and the second electromechanical converter are formed. By performing control to change the drive frequency of one of the two second drive signals input to the two first piezoelectric members for longitudinal vibration 22b-1 and the two piezoelectric members for second longitudinal vibration 22b-2, It is possible to change the relative movement speed between the vibrator 21 and the moving element 32.

FIG. 10 is an explanatory diagram showing the control of the driving frequency. The drive frequency control unit is configured by a multiplexer or the like, and can select a signal from the speed command unit. The switching elements Q1 to Q8 such as MOS field effect transistors can be turned on / off by the selected signal.

Resistors Rf1 to Rf8 having different resistance values are connected in parallel to the feedback section of the operational amplifier.
When the switching elements Q1 to Q8 connected in series to f1 to Rf8 are turned on by a control signal from a control signal generation unit, the amplification amount of the operational amplifier can be determined. As a result, the input drive signal is amplified by the operational amplifier, and the voltage control oscillator (VCO)
Is input to The voltage controlled oscillator (VCO) outputs a frequency according to the input voltage value.

A case where the driving frequency from the oscillator is changed will be described with reference to FIG. First, a case where the drive frequency is changed to a higher value will be described. In response to an instruction from the speed command unit, the drive frequency control unit turns on the switching element whose amplification factor increases and turns off the other switching elements. As a result, the voltage input to the voltage controlled oscillator (VCO) increases, and the driving frequency increases.

On the contrary, a case where the driving frequency is lowered will be described. In response to an instruction from the drive command unit, the drive frequency control unit turns on the switching element whose amplification factor decreases and turns off the other switching elements. As a result, the voltage input to the voltage controlled oscillator (VCO) decreases, and the driving frequency decreases.

In the present embodiment, in order to make the description easy to understand, the digital signal from the A / D converter is set to 8 bits, and the switching element and the resistor Rf are set to 8 bits.
It was made into pieces. However, the digital signal from the A / D conversion unit is set to 4 bits and the switching element and the resistor Rf
May be four in each case. Alternatively, the digital signal from the A / D converter may be 16 bits, and the number of switching elements and the number of resistors Rf may be 16 respectively.
Furthermore, you may set more. The greater the number of bits, the number of switching elements, and the number of resistors, the finer the control that can be performed.

Further, the control of the second L-phase drive signal voltage can be controlled by the configuration shown in FIG. T
The only difference from the phase drive signal voltage control is that the switching element is switched so as to increase the voltage as the rotational speed decreases.

In the present embodiment, the first L-phase drive signal voltage V
Although L1 was not changed, the speed of the moving element was changed from a high speed to a low speed as shown by a dashed line.
The L-phase drive signal voltage VL1 may be gradually increased.

In the present embodiment, the speed set by the speed setting unit is compared with the speed value detected by the speed detection unit, and the speed command unit outputs a command to eliminate the deviation. At the set speed between Nmax and the minimum rotation speed Nmin, the above-described T voltage control unit 49, L2-phase drive voltage control unit 50-2, and drive frequency control unit 52 are respectively controlled.

However, if a deviation occurs between the set value and the detected value at the target maximum rotation speed Nmax or the target minimum rotation speed Nmin and deviates from the determined driving frequency region, the driving frequency Is to keep the minimum or maximum value, and also keep the first L-phase drive signal voltage and the second L-phase drive signal voltage at the minimum or maximum value to control the T-voltage control unit that is most involved in the drive speed. Thereby corrects the driving speed.

(Third Embodiment) FIG. 12 is a perspective view showing an oscillator 61 constituting an ultrasonic actuator according to a third embodiment in an exploded state together with a control block diagram.

The vibrator 61 of the present embodiment is different from the vibrator 51 of the second embodiment in that a torsional vibration piezoelectric body 62 is provided.
a and 62b are arranged at positions (positions A and C in FIG. 2B) including two nodal positions of the generated torsional vibration, and the first longitudinal vibration piezoelectric body 62b-1 and the second longitudinal vibration The point is that the piezoelectric body for longitudinal vibration 62b-2 is arranged in a position including the node position of the generated longitudinal vibration (position B in FIG. 2B) in a state of being juxtaposed in the radial direction of the elastic body 23. .

The piezoelectric body for torsional vibration 6 arranged at the position A
The torsional vibration piezoelectric body 62a is arranged so that the shear displacement generated by 2a and the shear displacement generated by the torsional vibration piezoelectric body 62a arranged at the position C are generated in directions opposite to each other. You.

Further, unlike the first and second embodiments, the first longitudinal vibration piezoelectric member 62b-1 and the second longitudinal vibration piezoelectric member 62b-2 arranged at the position B are different from the elastic members 23b. Are arranged in parallel with the radial direction of the elastic body 23 on the two divided surfaces.

In the vibrator 61 of the present embodiment, the torsional vibration piezoelectric body 62a and the longitudinal vibration piezoelectric bodies 62b-1 and 62b-
Since the arrangement of 2 is changed, torsional vibration and longitudinal vibration can be efficiently generated in the vibrator 61.

(Modification) In each of the embodiments described in detail above, the ultrasonic actuator utilizing the ultrasonic vibration range is used as the vibration actuator. However, the vibration actuator according to the present invention and the control method thereof are different from those of the other embodiments. The same can be applied to a vibration actuator using a vibration region.

In the description of each embodiment, the vibrator has a substantially cylindrical shape. However, the vibrating actuator of the present invention is not limited to such a mode, but may have another column shape (such as a quadrangular prism shape). The same can be applied to an ultrasonic actuator having an outer shape.

In the description of each embodiment, an ultrasonic actuator using a vibrator utilizing primary longitudinal vibration and secondary torsional vibration has been taken as an example. However, an m-th order (m: natural number) )
The present invention can be equally applied to an ultrasonic actuator using the torsional vibration of the above and the longitudinal vibration of the nth order (n: natural number).

Further, in the description of each embodiment, the ultrasonic actuators having different modes and different inputs which combine the torsional vibration and the longitudinal vibration are used, respectively, in which the vibration generating inputs are independent. However, in the case of an ultrasonic actuator of a different shape and a different input in which different vibrations are combined, even in the case of a combination other than the torsional vibration and the longitudinal vibration, one of the vibrations is generated between the vibrator and the relative motion member. Between the vibrator and the relative motion member (clutch-like function).
If the ultrasonic actuator is involved in the above, it is possible to achieve exactly the same effect.

As such an ultrasonic actuator,
An ultrasonic actuator combining a plate-shaped vibrator with a longitudinal vibration mode and a bending vibration mode, and an ultrasonic actuator combining a donut-shaped disk-shaped vibrator with an annularly symmetric elongation vibration mode and a non-axisymmetric vibration mode And the like.

Further, even in the ultrasonic actuator of the same shape mode, the vibration mode generated in the elastic body is excited by different input, and one vibration mode is related to a driving function and the other vibration mode is a clutch function. If they are involved, the same effect can be produced.

As such an ultrasonic actuator,
An ultrasonic actuator that generates a driving force by generating two bending vibration modes in a columnar vibrating body such as a prismatic or cylindrical shape can be exemplified.

Further, in the description of each embodiment, an ultrasonic actuator using a piezoelectric material is used as the electromechanical transducer, but the present invention is not limited to such an embodiment, and other electric energy can be transferred. Any element that can be converted into mechanical displacement can be equally applied. For example, other than the piezoelectric body, an electrostrictive element, a magnetostrictive element and the like can be exemplified.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating an ultrasonic actuator according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an arrangement of a vibration piezoelectric body mounted on a vibrator in the ultrasonic actuator according to the first embodiment, together with an example of a torsional vibration mode and a longitudinal vibration mode generated in the vibrator. .

FIG. 3 is a perspective view showing a vibrator constituting the ultrasonic actuator according to the first embodiment in an exploded state together with a control block diagram.

FIG. 4 is an explanatory diagram showing, over time, generation of an elliptical motion on a driving surface of a vibrator by combining torsional vibration and longitudinal vibration generated in the vibrator.

FIG. 5 is a diagram illustrating control of each of a T-phase drive signal voltage VT, a first L-phase drive signal voltage VL1, and a second L-phase drive signal voltage VL2 in response to a speed command from a moving element in the ultrasonic actuator according to the first embodiment. It is a graph which shows an example.

FIG. 6 is an explanatory diagram showing control of a T-phase drive signal voltage.

FIG. 7 is an explanatory diagram showing control of a second L-phase drive signal voltage VL2.

FIG. 8 is a perspective view showing a vibrator constituting an ultrasonic actuator according to a second embodiment in an exploded state together with a control block diagram.

FIG. 9 is an explanatory diagram illustrating control of a drive frequency, a T-phase drive signal voltage, a first L-phase drive signal voltage, and a second L-phase drive signal voltage with respect to a speed command of a moving element according to a second embodiment of the present invention. It is.

FIG. 10 is an explanatory diagram showing control of a driving frequency.

FIG. 11 is an explanatory diagram showing a procedure for determining a drive frequency at a maximum rotation speed Nmax and a drive frequency at a minimum rotation speed Nmin.

FIG. 12 is a perspective view showing a vibrator constituting an ultrasonic actuator according to a third embodiment in an exploded state and together with a control block diagram.

FIG. 13 is a perspective view showing the structure of a vertical-torsional vibration type vibration actuator.

FIG. 14 is an exploded perspective view showing a stator of the vibration actuator shown in FIG. 13;

FIG. 15 is a longitudinal sectional view showing a structural example of a modified mode degenerate type vibration actuator.

FIG. 16 is a block diagram showing control of the vibration actuator of FIG.

17 (a) is a view of the semi-cylindrical vibrator shown in FIG. 15 as viewed from the bottom, and FIG. 17 (b) is a view of the vibrator shown in FIG. 15 as viewed from the side. is there.

FIG. 18 is a diagram illustrating a driving principle of a vibration actuator that generates an elliptical motion on a driving surface by combining torsional vibration and longitudinal vibration generated in a vibrator.

[Explanation of symbols]

 Reference Signs 20 ultrasonic actuator (vibration actuator) 21 vibrator 21a drive surface (end face) 22a torsional vibration piezoelectric body (first electromechanical converter) 22b longitudinal vibration piezoelectric body (second electromechanical converter) 22b-1 First piezoelectric body for vertical vibration (electromechanical conversion part) 22b-2 Second piezoelectric body for vertical vibration (electromechanical conversion part) 25a, 25b Electrode 40 Drive circuit 41 Oscillator 42 Phase shifter 43 T voltage amplifier 44-1 L1 voltage amplifying unit 44-2 L2 voltage amplifying unit 45 control circuit 46 speed setting unit 47 speed detecting unit 47 speed detecting unit 48 speed commanding unit 49 T voltage controlling unit 50 L2 voltage controlling unit

Claims (11)

[Claims] 1. A first electromechanical converter for generating a first vibration that vibrates in a plane parallel to an end surface of the main body, the main body having a columnar outer shape, and a first electromechanical converter in a direction different from the vibration direction of the first vibration. A vibration actuator comprising: a vibrator including a second electromechanical transducer that generates a second vibration that vibrates; and a relative motion member that performs relative motion between the vibrator and the second electromechanical transducer. The vibration actuator is characterized in that the unit is constituted by a plurality of independent electromechanical conversion units that convert electric energy into mechanical displacement. 2. The vibration actuator according to claim 1, wherein the plurality of electromechanical transducers are formed by an integrated electromechanical transducer and a plurality of divided electrodes mounted on a surface thereof. A vibration actuator, comprising a divided electromechanical transducer and a plurality of electrodes mounted on the surfaces thereof. 3. The vibration actuator according to claim 1, wherein the first vibration is a torsional vibration about an axis of the vibrator, and the second vibration is a vibration of the vibrator. A vibration actuator characterized by longitudinal vibration in an axial direction. 4. One of claims 1 to 3
In the vibration actuator described in the paragraph, one or two of the first electromechanical conversion unit is formed at a position including a node position of the first vibration generated in the vibrator, and the second electric machine A vibration actuator, wherein one conversion unit is formed at a position including a node position of the second vibration generated in the vibrator. 5. A first electromechanical transducer that generates a first vibration and a second electromechanical transducer that vibrates in a direction different from the vibration direction of the first vibration.
A method for controlling a vibration actuator, comprising: a vibrator having a second electromechanical transducer that generates vibration; and a relative motion member that performs relative motion between the vibrator and the second electromechanical transducer. A method of controlling a vibration actuator, comprising: dividing a portion into a plurality of regions; applying a drive signal to each of the regions; and individually controlling each of the drive signals to control the speed of the relative movement. 6. The method for controlling a vibration actuator according to claim 5, wherein a voltage of a drive signal applied to the first electromechanical converter is reduced, and a voltage of each of the second electromechanical converters is reduced. A method of controlling a vibration actuator, wherein the speed of the relative movement is reduced by increasing at least one voltage of a plurality of applied drive signals. 7. The method for controlling a vibration actuator according to claim 5, wherein a voltage of a drive signal applied to the first electromechanical converter is increased, and a voltage of each of the second electromechanical converters is increased. A method of controlling a vibration actuator, wherein the speed of the relative movement is increased by reducing at least one voltage of a plurality of applied drive signals. 8. One of claims 5 to 7
In the control method of the vibration actuator described in the paragraph, a drive signal applied to the first electromechanical converter, and
Controlling the speed of the relative movement by changing the frequency of at least one of the plurality of drive signals applied to each area of the second electromechanical converter. Method. 9. The method of controlling a vibration actuator according to claim 8, wherein the frequency is reduced, a voltage of a drive signal applied to the first electromechanical conversion unit is increased, and the second electric power is increased. A method of controlling a vibration actuator, wherein the speed of the relative motion is increased by reducing at least one voltage of a plurality of drive signals applied to each region of a mechanical conversion unit. 10. A vibrator, comprising: a first electromechanical converter that generates a first vibration; and a second electromechanical converter that generates a second vibration that vibrates in a direction different from the vibration direction of the first vibration. A vibration actuator comprising: a relative movement member that performs relative movement between the vibrator; and a drive circuit that applies a drive signal to the first electromechanical conversion unit and the second electromechanical conversion unit, At least one of the first electromechanical converter and the second electromechanical converter has a plurality of electromechanical converters for converting electrical energy into mechanical displacement, and the drive circuit includes the plurality of electromechanical converters. A vibration actuator, wherein a difference is generated in the amount of the mechanical displacement in the conversion part. 11. A vibrator, comprising: a first electromechanical converter that generates a first vibration; and a second electromechanical converter that generates a second vibration that vibrates in a direction different from the direction of vibration of the first vibration. A method of controlling a vibration actuator having a relative motion member that performs relative motion between the vibrator and at least one of the first electromechanical converter and the second electromechanical converter. A method for controlling a vibration actuator, comprising: dividing an electromechanical conversion portion that converts electric energy into mechanical displacement into a plurality of regions to cause a difference in the amount of the mechanical displacement between the regions.