JPH037077A - Ultrasonic motor device - Google Patents

Abstract

PURPOSE:To simplify the structure and to improve control performance by forming a resilient vibrator with such length and thickness as the resonance frequencies of longitudinal wave and bending wave coincide each other and arranging a pair of vibrators at specific positions with respect to the resilient vibrator. CONSTITUTION:A ultrasonic motor comprises a plate type resilient vibrator 10, a pair of vibrators 12a, 12b, and a motion extractor 20 arranged perpendicularly to the vibrating direction of bending wave and contacting directly or indirectly with at least one face of the resilient vibrator 10. The resilient vibrator 10 is formed to have such length and thickness as the resonance frequencies of longitudinal wave and bending wave coincide each other, and the pair of vibrators 12a, 12b are arranged, respectively, on the facing surfaces of the resilient vibrator 10 at the positions corresponding to the nodes of the longitudinal wave to be produced symmetrically to the longitudinally central point of the resilient vibrator 10. By such arrangement, moving direction of the motion extractor 20 can be controlled through a single-phase power source and the structure of ultrasonic motor and power source can be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ultrasonic motor device, and particularly to an ultrasonic motor device whose drive side is driven by a single-phase power source.

[Conventional technology]

Conventionally, ultrasonic motor devices that utilize ultrasonic vibrations are categorized based on the type of vibration generated in an elastic vibrating body: standing wave type ultrasonic motor devices that use standing waves, and traveling wave type m that uses traveling waves. There are two types: sonic motor devices.

Among the above devices, the standing wave type ultrasonic motor f device excites a single bending standing wave to an elastic vibrating body using a single-phase 'Il source, and connects it to the nodes of this standing wave via a motion extractor. A flat plate-shaped ultrasonic motor device is known that utilizes a driving force directed toward the object (see, for example, Japanese Patent Application No. 137395/1982, filed by the same applicant as this order).

In addition, the elastic vibrator has two independent vibration modes: longitudinal vibration (vibration spread in the length direction of the elastic vibrator) and natural vibration, which has a vibration component perpendicular to one surface of the elastic vibrator. A flat ultrasonic motor device that generates elliptical motion on the surface of an elastic vibrating body by exciting it with electric power yi (two-phase power supply), transmits this elliptical motion to a motion extracting body, and uses it as driving force. Are known. This type of flat ultrasonic motor device driven by a two-phase power source generates rotation of an elliptical motion on the surface of an elastic vibrating body by exciting two vibration modes with a temporal phase difference. By switching the direction, the direction of motion of the motion extractor can be switched between forward and reverse directions.

[Problems to be Solved by the Invention] Among the conventional techniques, a flat plate-shaped ultrasonic motor device that uses a single bending standing wave generated by a single-phase power source has an extremely complicated structure. Although it is simple, it has a control problem in that the direction of motion of the motion extractor in contact with the elastic vibrator cannot be reversed at the same frequency6.
Since the flat ultrasonic SO-7 device driven by a two-phase M1 source uses independent vibration modes of type 2a, an excitation source is required for each vibration mode. Compared to the sonic motor device, the ultrasonic motor device itself and the power source both have to be complicated, which is a problem α.

The present invention has been made in consideration of such problems of the prior art, and its purpose is to:
Driven by a single-phase power supply, it is possible to control the direction of motion of the motion extractor, and the structure of the ultrasonic motor device and power supply can be adjusted to rIRpH! The present invention is intended to provide an ultrasonic motor device that has the following features.

That is, a plate-shaped ultrasonic motor device that has the simplicity of an ultrasonic motor device driven by a single-phase power source and the controllability of a forward-reversible ultrasonic motor device driven by a two-phase power source, The aim is to achieve this goal.

[Means for solving problems]

In order to achieve the above object, the i11 sonic motor device of the present invention includes a plate-shaped elastic vibrating body and an alternating current of a specific frequency applied to the elastic vibrating body to (N+1/2)
(N: any natural number) wavelength and at least a pair of vibrators that generate a bending wave of a predetermined wavelength; The elastic vibrator has a length and thickness that match the resonance frequencies of longitudinal waves and bending waves, and the pair of vibrators are arranged on opposing surfaces of the elastic vibrator. are arranged respectively in
In addition, each vibrator is provided at a position corresponding to a node of the longitudinal wave generated at a symmetrical position with respect to the midpoint of the elastic vibrator.

[Effect]

When the resonant frequency of the longitudinal vibration (vibration in the spreading direction) of a plate-shaped elastic vibrating body matches the resonant frequency of the natural vibration mode that has a vibration component (bending vibration) perpendicular to the surface of the elastic vibrating body, It is generally known that when longitudinal vibration is excited, a natural vibration having a vibration component perpendicular to the surface of the elastic vibrator is also excited, and these two vibrations are coupled.

That is, if the plate-shaped elastic vibrating body is an ideal plane, J
11! No coupling occurs between mutually independent vibration modes, namely vibration and a natural vibration mode having a vibration component in a direction perpendicular to the longitudinal vibration. However, an actual elastic vibrating body has an asymmetry with respect to a plane horizontal to longitudinal vibration, and due to this asymmetry, when longitudinal vibration is excited, a natural vibration with a vibration component in a direction perpendicular to the longitudinal vibration is excited. is,
These are known to be easily bonded.

The ultrasonic motor f device according to the present invention utilizes the above-mentioned effect, and by exciting one of the pair of vibrators, it controls the asymmetry of the elastic vibrating body, and also controls the asymmetry of the elastic vibrating body vertically. Excite vibration. This longitudinal vibration excites bending vibration, and by combining these two vibrations, elliptical motion is generated on the surface of the elastic vibrator. This elliptical motion is transmitted to the motion extractor, and the motion extractor is driven in a fixed direction.

By selectively exciting one of the pair of vibrators, the phase of the coupling between the longitudinal vibration and bending vibration generated in the elastic vibrator changes, and the driving direction of the motion extractor is controlled. .

That is, by switching the excitation position of the plate-shaped elastic vibrating body, a 180 degree phase difference is created in the combined phase of longitudinal vibration and bending vibration, and the direction of rotation of the elliptical motion generated on the surface of the elastic vibrating body is reversed. You can switch as follows.

[Principle of the present invention]

In the case of simple bending vibration, as shown in FIG. 9, if both ends are open, the nodes of vibration are distributed symmetrically about the center of the plate-shaped vibrating body 100, and each point has a direction of the arrow pointing to the nearby node. The driving force is generated.

The driving force is therefore distributed symmetrically about the center and is independent of the position of the excitation source.

On the other hand, in the case of vibrations in which longitudinal vibrations and bending vibrations are combined, if both ends of the vibrating body are open, the bending vibrations are considered to be symmetrical about the center, so there are two possible cases: a case in which the longitudinal vibrations are symmetrical and a case in which they are antisymmetrical. It will be done.

In Figure 10 (,) (), ), if the displacement in the X direction (spreading direction) and the displacement in the XtS' direction (direction perpendicular to the plane) is Y, the above two cases are expressed as the following equations. .

(1) X= a cos(klx) cos(we
)Y” b cos(k2x) sin(wt+d)(
2) X= a 5in(klx) coS(
we) Y= b eos(k2x) sin(wt+d
) (kl: wave number of longitudinal wave 2: wave number of bending wave 111: angular frequency) When the longitudinal wave in equation (1) is symmetrical, α is in the same direction as the point X on the plate-shaped vibrating body. It can be seen that rotational elliptical vibration occurs. That is, unlike the case of simple bending vibration mentioned above,
It is possible to generate a driving force in the same direction at the point X and the point -.

When the longitudinal vibration in equation (2) is antisymmetric, elliptical vibration occurs in the opposite direction to the points on the flat plate, and the driving force is in the opposite direction.

Also, in both equations (1) and (2), each point is an elliptical vibration, so
The front and back sides of the plate-shaped vibrating body 100 have driving forces in opposite directions, which is also different from the case of simple bending vibration.

From the above considerations, an ultrasonic motor device driven by a single-phase power source and capable of forward and reverse rotation can be configured as follows.

■ When the driving forces of α of X and -X are in the same direction (10th
Figure 0 (a)) Assuming that one wave of longitudinal waves is riding on the vibrating body 100, for excitation, excitation sources A and B are placed at the nodes of the longitudinal wave, as shown in Figure 110 (,). Figure 10 (
, ) is obtained. Next, if we consider the case of excitation by excitation iB, this is nothing but a case in which the excitation of excitation source A is rotated by 180° with respect to the center MO, and the excitation of excitation source B is reversed from that shown in Fig. 10(a). It can be seen that a driving force in the direction can be obtained.

That is, when the length of the vibrating body 100 is an integral multiple of the wavelength of the longitudinal wave,
By installing longitudinal wave excitation sources at centrally symmetrical positions on the same plane of the vibrating body 100, by selectively driving one of them one by one, the coupling phase between the longitudinal vibration and the HIti vibration generated in the vibrating body can be controlled. This means that the forward and reverse directions of the driving force can be controlled.

When the driving force at the points X and 1× is in the j direction (Fig. 10 (b)
)) In this case, forward and reverse rotation control becomes possible with a configuration as shown in FIG. 10(b). That is, the longitudinal wave is the vibrating body 100.
For example, as shown in Fig. 10(b), an excitation leakage is placed at the node of the longitudinal wave generated on the left side of the center line O, and the excitation is An excitation source B is placed at a node of a longitudinal wave generated on the right side of the center #aO on the surface facing the source A.

Assume that the driving force shown in FIG. 10(b) is obtained by the excitation source A. Next, considering the case of excitation by excitation fi, B,
This means that the phase of the longitudinal wave is the same as in the case of excitation from excitation source A, but
Since the phases of the bending wave components differ by 180°, the driving force in the opposite direction to that shown in FIG. 10 (1,) is obtained by the excitation of the excitation aB.

In other words, the length of the vibrating body 100 is the wavelength of the longitudinal wave (N +
l/2) times (N: any natural number), if longitudinal wave excitation sources are installed at the opposite sides of the vibrating body 100,
By selectively driving one of them one by one, the coupling phase of the longitudinal vibration and bending vibration generated in the vibrating body can be controlled, and the forward and reverse directions of the driving force can be controlled.

In Uni, assuming that the vibration mode with a vibration component perpendicular to the plane to be coupled to the longitudinal vibration is bending vibration, in order to couple the bending wave to a single longitudinal wave, the dimensions of the plate-shaped vibrating body can be calculated using the following formula. You can take it like this.

That is, 't: plate thickness; plate length α is 5 inches (α/2) cosh (α/2) + cos (α/2
) sinb(α/2)=0, which corresponds to the order of the resonance mode of symmetrical bending vibration from the smallest order. The resonance frequency "1" is given by: E: Young's modulus ρ: density.

The present invention is based on the above item (2), and as shown in FIG. Vibrators 12a and 12b, which are excitation sources made of piezoelectric ceramic or the like, may be bonded to the surfaces, respectively.

Each vibrator 12a provided on opposing surfaces of the vibrator 10
, 1211, the asymmetry of the vibrating body 10 is controlled, whereby each vibrator 1
The bending waves generated by 2a and 12b have a phase difference of 180°.

That is, when the exciter 12a is excited, a slight bending vibration component is generated due to the asymmetry of this part. - If a bending vibration component occurs, the vibrating body 10 is considered to be asymmetrical, and a combination of longitudinal vibration and bending vibration occurs.

Also, considering the case where the vibrator 12b is excited, the longitudinal waves are in phase, but the situation in which the bending wave component occurs is that the vibrator 12b is in phase.
The phase is 180° different than when a is excited. Therefore, the coupling between the longitudinal vibration and the bending vibration has a phase difference of 180° from that when the vibrator 12a is excited, and the direction of the elliptical motion is reversed.

In other words, in the case of Fig. 1, since the wavelength of the longitudinal wave is 1.5, in-phase longitudinal waves are generated by the vibrators 12a and 12b (in-phase longitudinal waves for deformation in the same direction), but the combined bending waves are The phases are different by 180°.

〔Example〕

Hereinafter, the ultrasonic motor device according to the present invention will be explained in detail based on the drawings.

1 and 2 show an embodiment of an ultrasonic motor device according to the present invention, in which vibrators 12a and 12b are attached to both sides of a plate-shaped elastic vibrator IO. Each vibrator 12a
, 12b are connected to one end of lines 14a, 14b, and the other ends of these lines 14a, 14b are connected to a switch !, which is a switching means. 1416 are connected to terminals 16a and 16b, respectively. The line 14c has one end connected to the elastic vibrator 10, and the other end connected to the single-phase power supply 18.
It is connected to the. The single-phase power supply 18 is connected to the line 14d,
It is connected to the switch 16c of the switch mechanism 16.

Further, on the side of the elastic vibrating body 10 where the vibrator 12a is provided, a motion extracting body 20 is arranged so as to be in direct contact with the elastic vibrating body 10.

The elastic vibrating body 10 is formed to have such a thickness that the longitudinal waves generated by each vibrator 12a=12b match the resonance frequencies of the bending waves generated by the longitudinal waves.

Each vibrator 12a, 121+ is arranged on the elastic vibrating body 10 at a position corresponding to a node of a longitudinal wave generated at a symmetrical position with respect to the midpoint of the longitudinal axis of the elastic vibrating body 10.

(1) The phase power supply 18 applies an alternating current of a specific frequency to either the vibrator 12a or 12b by switching the switch 16c. /2) (N: Any natural number) This generates a longitudinal wave of the boyfriend and a bending wave of a predetermined wavelength generated thereby.

The motion extracting body 20 is a roller-shaped body that is positioned on the elastic vibrating body 10 by any means, pressurizes the elastic vibrating body 10 by any pressurizing means, and is rotatable in any direction. te(do)

Next, the operation of the ultrasonic motor device having the above configuration will be explained.

FIG. 1113 shows a case where a 1.5-wave longitudinal wave and a 1-wavelength bending wave are generated, and by switching the switch 16 to excite the vibrator 12a or the vibrator 121, These excitations generate in-phase longitudinal waves (in-phase longitudinal waves for deformations in the same direction), but depending on which of the vibrators 12a and 12b is excited, the phase of the coupled bending waves can vary by 180 degrees.゛ It will be different. Therefore, by selectively exciting the vibrators 12a and 12b, the direction of motion of the elliptical vibration generated on the surface of the elastic vibrating body 10 changes, and the direction of the motion taken out to the motion extracting body 20 is changed as shown in FIG. And, as shown by solid line arrows and broken line arrows in FIG. 2, forward and reverse transmission is possible. Therefore, if an object to be transported, such as a card-like object or paper work, is brought into contact with the motion extractor 20, the object can be transported in any direction by switching the switch 16C.

Further, FIG. 4 shows an example in which a longitudinal wave of 1.5 wavelengths and a bending wave of two wavelengths are combined. In all of these cases, the longitudinal wave nodes are located approximately at the center of the vibrator.

Further, the embodiment shown in FIGS. 5(a) and 5(b) shows a state in which a thick card-like object 22 is transferred, and a movement extracting object 20 is attached to an arm 50 vertically installed on a base member (not shown).
is rotatably supported. This movement extractor 20 is
A pressure roller 52 is rotatably supported above the motion extracting body 20 of the 7-arm 50 and is pressed in the direction of the motion extracting body 20 by a pressure means (not shown). and is pressed onto the elastic vibrating body 10.

In this embodiment as well, the vibrators 12a and 12b are
By excitation, the card-like body 22 can be transferred in the direction of the solid line arrow or the dashed line arrow direction in the tISs diagrams (a) and (b).

Further, the embodiments shown in FIGS. 6(a) and 6(b) show the state in which the card-like bodies 22a and 22b are transferred, and in particular, in FIG. 6(b), the pressure roller 54 is used as the pressure means.
This shows the case where . Also in this example,
Of course, the motion extracting bodies 20a, 206 and the pressurizing a-ra 54 may be supported by a predetermined arm.

In FIG. 6 (aHb), two card-like bodies 22a, 2 are placed on the same surface of the elastic vibrating body 10 with the vibrator 12a in between.
2h is transferred in opposite directions. Of course, only one of the motion extractors 20a and 20b is provided,
Either one of the card-like bodies 22a, 22b can be transferred.

Furthermore, FIG. 7 shows the motion extracting body 20 which is rotatably supported by a 7-mem 50 and is pressed onto the elastic vibrating body 10 by a pressurizing means (not shown), and the elastic vibrating body 10. This shows a state in which a thin paper sheet 24 is held under pressure between the two, and the paper sheet 24 is transferred in the direction of the solid line arrow or in the direction of the broken line arrow in Figure #57. When the thickness of the paper products 24 is extremely thin, the elastic vibrating body 10
The elliptical motion generated on the surface is extracted by the motion extractor 20. The paper sheets 24 are transported depending on the direction of motion of the motion extraction body 20.

Further, FIG. 8 (aHb) shows a modification of the motion extracting body, which is a protruding motion extracting body 200 that does not have oral transmission. FIG. 9(,) corresponds to FIG. 1, and FIG. 8(b) shows a modification of the motion extracting body corresponding to FIG. 1117, respectively. In this case as well, the elliptical vibration generated on the surface of the elastic vibrating body 10 is extracted by the motion extracting body 200 as in each of the above embodiments, and the same effects as in each of the above embodiments can be obtained.

Although not particularly illustrated, the shape of the motion extractor is not limited to that described in each of the above embodiments.
Of course, it may be a hemispherical body or the like, and any shape that can extract the elliptical vibration generated on the surface of the elastic vibrator is sufficient.

〔Effect of the invention〕

Since the present invention is configured as described above, it produces the effects described below.

It is possible to provide an ultrasonic motor device in which a single-phase current is applied to the vibrator and the drive circuit for the vibrator is simple.

Further, by switching and applying a pattern current of a specific frequency to either one of the pair of vibrators, the direction of motion of the motion extractor can be controlled.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view showing an embodiment of the present invention, FIG. 2 is a perspective view of what is shown in FIG. 1, and FIGS. 3 and 14 show the state of coupling of longitudinal waves and bending waves according to the present invention. Explanatory diagram, Figure 5 (a) (+1) shows another example of real power, Figure 5 (,) is a schematic perspective view, Figure 15 (1) is a side view of Figure 5 (,), t
ls G fi (a) (b) shows an example of a pond, FIG. 6 (,) (1,) shows an example of transferring two card-like bodies in different directions, , ) is a schematic perspective view in which the pressure means is not shown separately, Pt56 (b) is a schematic perspective view showing the case where a pressure roller is used as the pressure means, and FIG. FIG. 8(a) is a side view showing an embodiment in which paper sheets sandwiched between the two are transported.
(+1) is a side view showing a modified example of the motion extracting body;
The leap is an explanatory diagram showing the driving direction by bending waves, Fig. 10 (a
) and (b) are explanatory diagrams showing driving directions by combined vibration of longitudinal vibration and bending vibration. Explanation of symbols in Figure 7 10 - Vibrator 12a, 12b, Vibrator 14a, 141), Line 14c, 14d, Line 16, 16a, Terminal 16b, 16c, Switch 18, 20.20a, 20b・・Motor extractor 20.22g,
22b-・Card-like body 24・・Paper sheet 50・・Arm 52.54・・・Pressure roller 100・・Vibrating body 200・B・・Excitation [A・・・Vibrator・・Line/Line/Switch Mechanism, terminal, single-phase power supply, motion extractor, excitation source Figure Z Figure 3 Figure 4 Figure 6 Figure 0 Figure 5 ( ) (b) 40 Figure 7

Claims (2)

[Claims] 1. a plate-shaped elastic vibrating body; and at least a pair of vibrations that generate a longitudinal wave with a wavelength of (N+1/2) (N: any natural number) and a bending wave with a predetermined wavelength in the elastic vibrating body by applying an alternating current of a specific frequency to the elastic vibrating body. and a motion extractor in contact with at least one surface of the elastic vibrating body perpendicular to the vibration direction of the bending wave, the elastic vibrating body generating resonance of each of the longitudinal wave and the bending wave. The pair of vibrators are formed to have lengths and thicknesses that match each other in frequency, and the pair of vibrators are disposed on opposing surfaces of the elastic vibrator, and each vibrator is located at a symmetrical position with respect to the midpoint of the longitudinal axis of the elastic vibrator. An ultrasonic motor device characterized in that the ultrasonic motor device is provided at a position corresponding to a node of the longitudinal wave generated in the wave. 2. 2. The ultrasonic motor device according to claim 1, further comprising switching means for switching and applying the alternating current of the specific frequency to either one of the pair of vibrators.