JPH08242592A - Ultrasonic actuator - Google Patents

Abstract

(57) [Summary] [Object] To provide an ultrasonic actuator that does not require a complicated vibration system, has a large degree of freedom in the shape and dimensions of the vibrating body, and can easily change the moving direction of the moving body. [Structure] On both sides of a rod-shaped elastic body 1 having a flat cross section,
The vibrating body 2 was constructed by attaching the piezoelectric bodies 3a and 3b so that the polarization directions thereof were opposite to each other. Support pins 6 are provided in the center of the left and right sides of the elastic body 1, and the vibrating body 2 is fixed to the support frame via the both support pins 6. Piezoelectric body 3a attached to the upper surface of the elastic body 1
Is connected to the two-phase oscillator 9 via the amplifier 7 and the phase shifter 8, and the piezoelectric body 3b attached to the lower surface is connected to the two-phase oscillator 9 via the amplifier 10.
It was connected to the phase oscillator 9. The elastic body 1 was grounded. The output frequency of the two-phase oscillator 9 was set to the resonance frequency of the primary longitudinal vibration of the vibrating body 2. + 90 ° or −90 ° on both piezoelectric bodies 3a, 3b
The voltage is applied with the phase difference of (1), and the direction of the elliptical locus of the displacement in which longitudinal and bending vibrations are coupled in the axial direction of the end face is changed by changing the phase difference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic actuator having a rod-shaped vibration generator.

[0002]

2. Description of the Related Art Various actuators have been proposed in which ultrasonic vibration generated by applying a resonant alternating voltage to an electrostrictive element or a piezoelectric element is converted into rotational movement or linear movement to obtain driving. For example, in Japanese Examined Patent Publication No. 6-67228, a Langevin type oscillator or a piezoelectric element is used as an excitation source in a vibrating body to generate a standing wave, and the vibrating body is provided between the antinode and the node of the standing wave. A device has been proposed in which the generated motion component in the node direction from the abdomen is selected by an extractor (projection) provided on the vibrating body and transmitted to the moving body. As shown in FIGS. 24A and 24B, a plurality of protrusions 31 are provided for the vibrating body 32,
The interval is not less than 1/2 wavelength of the standing wave S and its width is not more than 1/4 wavelength of the standing wave. As shown in FIG.
The displacement of the vibrating body 32 due to the vibration is different between the antinode L and the node N, and the direction of the motion component is from the antinode L to the node N. Therefore, with respect to the rod-shaped vibrating body 32, each projection 31 is divided into four equal wavelength sections λ and divided into unit sections A1, A2, A3, A.
When it is provided in the even-numbered sections A2 and A4 of FIG.
The moving direction of the moving body 33 that comes into contact with the protrusion 31 is opposite between the case (a)) and the case where it is provided in the odd-numbered sections A1 and A3 (FIG. 24B).

The Proceedings of ASJ: p147-14
8 (March 1988), a flat plate motor using a vertical-bending multimode oscillator is reported. This motor has a rectangular metallic flat plate with a longitudinal vibration (longitudinal direction) primary resonance mode,
Bending vibration (width direction) is degenerated and each resonance mode is piezoelectrically excited with a phase difference of 90 °. As shown in FIG. 26, an elliptic motion of displacement as shown in the figure is formed in the flat piezoelectric vibrator 34, and when the roller is brought into pressure contact near the center in the width direction,
A driving force in the direction indicated by arrow 35 is obtained. When the phases of the two-phase drive are reversed, the directions of displacement of the elliptic motion are reversed.

[Proceedings of the Acoustical Society of Japan: p1057-1]
In 058 (March 1994), as an ultrasonic motor with a simple structure and a possibility of reversing operation, a longitudinally arranged obliquely symmetrical piezoelectric plate is used.
An ultrasonic motor utilizing flexural coupling vibration has been reported. As shown in FIG. 27A, this ultrasonic motor uses a parallelogram type piezoelectric plate 36 to couple longitudinal vibration and bending vibration in the width direction to excite the bending vibration of the piezoelectric plate 36. Piezoelectric plate 36
Is rotatably supported by a jig 38 via a support rod 37, and is urged to rotate by a spring (not shown) in a direction in which it abuts the rotor 39. The rotation direction of the rotor 39 can be changed by changing the drive frequency.

[0005]

[Problems to be Solved by the Invention] Japanese Patent Publication No. 6-67228
In the device disclosed in the publication, in order to extract a unidirectional motion component, the interval between the protrusions 31 is set to 1/2 wavelength or more of the standing wave S, and the width thereof is 1/4 wavelength of the standing wave S. Must be: Therefore, it is necessary to accurately process the positions and sizes of the large number of protrusions 31 provided on the vibrating body 32, which requires a great amount of time for precision processing of the large number of protrusions 31, resulting in a high manufacturing cost.

Although the position where the protrusion 31 is provided is between the antinode and the node of the standing wave S, it is difficult to exactly specify the antinode and node of the actual standing wave of the vibrating body. because,
This is because there are practically non-uniformities when attaching the excitation source to the vibrating body, non-uniformity of the vibrating body, and the like. Further, the displacement of the vibrating body due to the vibration is different between the antinode L and the node N, and the direction of the motion component is from the antinode L to the node N. Therefore,
Between the belly L and the node N, two motion components are combined to generate an elliptical locus. Further, since the elliptical locus is generated differently depending on the place, when a large number of protrusions are provided, it is not possible to provide all the protrusions at the same displacement place, and there is also a problem that the utilization efficiency of the motion component deteriorates.

Further, since the direction of the motion component is divided into the left and right with the antinode L of the standing wave S as a boundary, one of the motion components must be selected, and the moving direction of the moving body is limited to one direction. There is a problem that is.

Further, in general, when the rod-shaped vibrating member becomes long, unnecessary vibration is likely to occur, and it becomes difficult to carry out the desired excitation. Therefore, there is a problem that it is difficult to accurately move the moving body over a long distance.

Further, in a flat plate motor using a longitudinal-bending multimode oscillator, two resonance modes must be combined to obtain an elliptical locus of displacement. However, there is a problem that the degree of freedom in shape and size is small.

Further, in the ultrasonic motor using the longitudinal-bending coupled vibration of the obliquely symmetrical piezoelectric plate, the vibrating body must have a special parallelogram shape, and depending on the values of d, T and θ in FIG. 27 (b). Vibration state is different. In addition, the output that can be taken out differs depending on the contact position of the rotor 39, and an upper mode in which a driving force is generated toward the tip side of the parallelogram,
The contact position where the maximum output is obtained is different in Lower mode where the driving force toward the opposite side is generated. Moreover, there is a problem that it is very difficult to make the rotation characteristics in both directions equal.

The present invention has been made in view of the above-mentioned conventional problems, and a first object thereof is an ultrasonic wave which does not require a complicated vibration system and has a large degree of freedom in the shape and size of the vibration body. It is to provide an actuator. A second object is to provide an ultrasonic actuator capable of easily changing the moving direction of the moving body.

[0012]

In order to achieve the first object, in the invention according to claim 1, at least one end is supported in a free state, and a plurality of polarizations having different polarization directions are present. And a power supply unit for applying a resonance drive voltage of longitudinal vibration to the piezoelectric body in order to generate longitudinal vibration and bending vibration in the axial direction of the rod body. The length of the rod-shaped body in the axial direction resonates with the longitudinal vibration so that the antinode of the vibration exists at the free end of the rod, and the movement of the mass point of the free end of the power generator is elliptical. A voltage having a phase difference can be applied to the piezoelectric body in order to generate in-plane strain due to expansion and contraction in the axial direction which is a locus.

Further, in the invention according to claim 2, the vibration generating part is composed of a flat rod-shaped elastic body and a piezoelectric body arranged on both sides or one side of two surfaces facing each other in the thickness direction. And

In order to achieve the second object, the invention according to claim 3 is characterized in that, in the invention according to claim 1 or 2, the power source section is provided with a phase difference of applied voltages to the piezoelectric body. Switching is possible at ± 90 ° or its vicinity.

The longitudinal frequency f (Hz) of a straight rod-shaped elastic body which is not so thick is expressed by the following equation. f =
{Λ _n / (2πl)} √ (E G / γ) ... l: rod length (cm) E: Young's modulus (kg / cm ² ) γ: unit volume weight (kg / cm ³ ) λ _n : A dimensionless coefficient determined by boundary conditions and vibration modes G: Gravitational acceleration The primary and secondary vibration modes of the rod-shaped elastic body 1 with free ends are as shown in Fig. 1 (a), one end fixed and the other end free. The primary and secondary vibration modes of the rod-shaped elastic body 1 of FIG.
As shown in (b). As is clear from the equation, the longitudinal frequency changes depending on the length of the rod-shaped elastic body regardless of its cross-sectional area if the material is constant. Although the vibration mode of the rod-shaped elastic body with free ends is different from the vibration mode of the rod-shaped elastic body with one fixed end and the other end free, the basic frequency is the same except that the value of λ _{n in} the formula is different.

The relationship between the length of the vibrating body (elastic body) and the resonance frequency of the longitudinal vibration has a constant relationship depending on the order of the vibration mode. If the relationship between the materials of the elastic body is obtained in advance, the resonance frequency of longitudinal vibration can be obtained by setting the material of the elastic body, the length of the elastic body, and the mode to be used. However, it also varies depending on the supporting state of the vibrating body, and the relationship is different between the case where both ends are free and the case where one end is fixed and the other end is free. For example, when steel is used as the material of the elastic body, the relationship between the length of the elastic body and the resonance frequency of longitudinal vibration is as shown in FIG.

Generally, when the longitudinal vibration is excited, the vibration locus of the ends of the rod-shaped elastic body with free ends is exaggeratedly shown in FIG. That is, in the case of longitudinal vibration excitation, extension-contraction is repeated at the end of the elastic body 1. In this case, there is only the vibration component in the central axis direction. Even when the one end is fixed and the other end is free, the expansion and contraction are repeated near the free end, and it is considered that the situation on the right side of FIGS. 2A and 2B occurs.

The inventor of the present application selects, on the basis of this longitudinal vibration, a rod-shaped elastic body in which bending vibration is easily coupled to the center in the axial direction, and determines the piezoelectric body arrangement that causes bending strain and the timing of strain generation. It was found that the direction can be changed by controlling the phase difference of the voltage and generating an elliptical locus of displacement at the end of the vibrating body.

As is well known, this bending vibration is considered to be as shown in FIG. 3 when the vibration locus of the end portion of the elastic body 1 is exaggerated as in FIG. Actually, as shown in FIG.
3 (a) and 3 (b) when the longitudinal vibration excitation of FIG.
Bending vibrations are simultaneously coupled, and an elliptical locus of the displacement portion at the end of the elastic body is obtained.

As for the shape of the rod-shaped elastic body (the cross section near the piezoelectric body attached), the shape in the cross section orthogonal to the central axis of the rod-shaped elastic body is the X direction and the Y direction with the central axis as the Z direction.
When the directions are set as shown in FIG. 5, a shape having isotropic dimensions in the X and Y directions (a circle as shown in FIGS. 5A and 5B,
It is preferable that the Y dimension is smaller than the X dimension instead of the square shape. This is because it is difficult to selectively cause bending in the Y direction with a shape having isotropic dimensions in the X and Y directions. As a specific example of the preferable shape, FIG.
There are a rectangle shown in FIG. 5C, a shape obtained by cutting a part of a circle shown in FIG. 5D, and a shape shown by cutting both ends of the rectangle shown in FIG.

Further, in the case of a flat shape, when it contracts in the thickness direction, it expands in the lateral direction due to the Poisson's ratio, and when it expands in the thickness direction, it contracts in the lateral direction. Therefore, if the width of the flat type is widened, the higher order resonances in the lateral direction are coupled to each other, so that a complicated resonance is likely to occur. When flat, the width is preferably about 4 to 5 times the thickness.

The cross section of the rod-shaped elastic body in the direction of the central axis is preferably uniform over the entire length, but even if the thickness dimension in the Y direction is slightly increased only in the vicinity of the end portion, an additional mass effect of vibration is given. Good. Similarly, (c), (d), and
The cross section of (e) shows an ideal cross section of the piezoelectric body attachment site, and the end may have a shape in which FIGS.

As the length of the rod-shaped elastic body, the length obtained from the equation is selected according to the vibration mode and resonance frequency to be used. For example, when the material of the elastic body is steel and the longitudinal primary or secondary vibration mode is used, when the longitudinal resonance frequency of about 100 kHz is used, the length of the elastic body is about 25 to 6
The range is about 0 mm.

The vibrating body 2 constituting the vibration generating portion is composed of the elastic body 1 and the piezoelectric body (piezoelectric element) 3 (see FIG. 6).
(A) and (d)) and a case where the piezoelectric body 3 is composed of a plurality of piezoelectric bodies 3 (FIGS. 6B and 6C) are considered (the arrow in the figure indicates the polarization direction of the piezoelectric body). . When it is desired to reduce the voltage applied to the piezoelectric bodies 3, the thickness of each piezoelectric body 3 may be reduced and two or more piezoelectric bodies 3 may be combined and laminated (FIG. 6C). ). Further, as shown in FIG. 6D, the elastic body 1 may be arranged on both end surfaces of the piezoelectric body 3.
The polarization directions of the piezoelectric bodies 3 arranged so as to face each other are opposite. In the case of FIG. 6D, a lining material may be used instead of the elastic bodies 1 provided on both sides of the piezoelectric body 3. The basic structure of the vibrating body 2 is the same regardless of whether both ends are free or one end is fixed and the other end is free.

As the material of the elastic body, for example, metal such as steel, aluminum, stainless steel, or ceramics is used. Further, as the lining material, for example, wear-resistant fluoroplastic or the like is used. Examples of the piezoelectric body include piezoelectric ceramics such as barium titanate and PZT (polycrystals of zirconate / lead titanate), polymer piezoelectric materials such as polyvinylidene fluoride and vinylidene cyanide polymers, and piezoelectricity. A polymer composite piezoelectric material in which the ceramic fine particles are dispersed in a polymer is used.

In order to construct the piezoelectric body so that there are a plurality of polarizations having different polarization directions, two or more piezoelectric bodies may be used as follows, or the piezoelectrics whose polarization directions are opposite to each other on the way. One body may be used.

FIG. 5 which is composed of an elastic body 1 and a piezoelectric body 3.
As an arrangement form of the piezoelectric body 3 in the vibrating body 2 in the case of (a), for example, there are forms shown in FIGS. In the example of FIG. 7A, two piezoelectric bodies 3 having different polarization directions are arranged only on one side of the elastic body 1. still,
Instead of arranging two piezoelectric bodies 3, one piezoelectric body 3 whose polarization directions are opposite to each other may be arranged. In the example of FIG. 7B, one piezoelectric body 3 having different polarization directions is arranged on each side of the elastic body 1. In the example of FIG. 7 (c), two elastic bodies 1 are provided on each of the upper and lower surfaces (one piezoelectric body 3 whose polarization direction is opposite in the middle may be provided), and they are arranged at opposing positions and adjacent positions. The piezoelectric bodies 3 are arranged so that their polarization directions are different from each other. Figure 7 (c)
In this arrangement, the piezoelectric bodies 3 arranged on one side of the elastic body 1 or the piezoelectric bodies 3 obliquely arranged with the elastic body 1 interposed therebetween are driven as a pair.

FIG. 6A, which is composed of an elastic body 1 and a piezoelectric body 3.
In the case of the vibrating body 2 shown in (1), the area to be attached to the elastic body 1 as the piezoelectric body 3 is preferably a large area having substantially the entire length a and width b of the elastic body 1. This is because a larger area is preferable as the vibrating body 2 because a larger electric input can be input to the piezoelectric body 3. The lower limit of the area of attachment of each piezoelectric body 3 to the elastic body 1 is preferably about 1/2 of the area of one surface of the elastic body 1. That is, the lower limit value of the total area of the attachment surfaces of the two piezoelectric bodies 3 is ab. If the attachment area of the piezoelectric body 3 is less than the lower limit value, bending vibration may be difficult to be excited. Further, in the case of a vibrating body having free ends, it is preferable that the piezoelectric body is attached to the elastic body 1 near the center of the entire length of the elastic body 1. When one end is fixed and the other end is free, it is preferable to dispose the piezoelectric body 3 in the vicinity of the fixed portion.

The polarization direction of the piezoelectric body 3 is preferably orthogonal to the central axis of the vibrating body 2. At the same time, it is optimal to use a piezoelectric body (using the piezoelectric lateral effect) that is distorted in a direction perpendicular to the polarization axis. Therefore, the bending vibration is excited in the same direction as the polarization direction of the piezoelectric body.

Further, in order to facilitate the attachment of the support piece 2a for firmly supporting and fixing the vibrating body 2, FIG.
As shown in, the piezoelectric body 3 may be divided into left and right without attaching the piezoelectric body 3 near the center of the elastic body 1. However, in this case, when the both-end free / free primary vibration mode is used, the support piece 2a and the like may be provided in the vicinity of the vibration node position in accordance with the used vibration mode.

[0031]

According to the inventions of claims 1 and 2,
When a resonance drive voltage of longitudinal vibration having a different phase difference is applied from the power source section to the piezoelectric body of the vibration generating section, the vibration generating section which is a rod-like body vibrates in the state where the antinode of the vibration exists at its free end. In-plane strain is generated at the free end of the vibration generating part due to axial expansion and contraction, where the movement of the mass point becomes an elliptical locus,
When the moving body is brought into contact with the free end portion of the vibration generating portion, the moving body relatively moves via frictional force in the direction opposite to the direction of the elliptical locus of the displacement occurring at the free end portion of the vibration generating portion.

For example, as shown in FIG. 8, in the vibrating body 2 in which the piezoelectric bodies 3 are attached to both surfaces of the elastic body 1, the piezoelectric body 3 on the first surface (upper surface) is the A phase and the second surface (lower surface). The AC drive voltage for causing the longitudinal vibration to resonate is applied with the piezoelectric body 3 of B) as the B phase. The arrow indicates the polarization direction of the piezoelectric body 3.

When the A and B phases have the same phase (Phase 0 °), the drive voltage waveforms shown in FIG. 9A are obtained, the piezoelectric bodies on the upper and lower surfaces have the same distortion, and the axial direction at the end of the vibrator. Only vertical vibration occurs in the.

On the other hand, when a phase difference of 90 ° is given to the A and B phases (Phase 90 °), the result is as shown in FIG. 9B. Taking this time lapse as a representative of the strokes of I, II, III, and IV, the in-plane strain of the vibrator end portion at that time is schematically shown in FIG.
It shows in (d). In the process of I shown in FIG.
The phases grow together, and the A phase contracts and the B phase expands in the process of II shown in FIG. 10 (b). In the process of III shown in FIG. 10 (c), both A and B phases shrink, and in the process of IV shown in FIG. 10 (d), A phase expands and B phase contracts. Therefore, it can be seen that the movement of the mass point m at the end of the vibrating body becomes an elliptical locus as shown in FIG.

Although the example of FIG. 9B shows the 90 ° advance phase, in the case of the 90 ° delay phase (270 ° advance phase) as well, the in-plane strain at the end of the transducer is I → IV →
This occurs in the order of III → II, and the movement of the mass point at the end of the vibration body is
As shown in (b), it becomes an elliptic locus clockwise.

When the phase difference is 180 °, the B phase expands when the A phase contracts, and the A phase contracts when the B phase expands next, so that it is shown in FIGS. 10 (b) and 10 (d). The states of II and IV occur alternately, and the elliptical locus does not occur.

When the moving body 4 is brought into contact with the free end portion of the vibrating body 2 in a vibrating state where an elliptical locus of displacement is generated at the end portion of the vibrating body 2, the moving body 4 is moved. Moves via frictional force in the direction opposite to the direction of the elliptical locus of the displacement generated at the free end. Further, as shown in FIG. 12B, when the rotatably supported disk-shaped moving body 4 is brought into contact with the free end portion, the moving body 4 has an elliptical locus of displacement around the support shaft 5. Rotate in the opposite direction. If the body that abuts on the free end of the vibrating body 2 is fixed and the vibrating body 2 is movable without fixing the vibrating body 2 side, the vibrating body 2 can also be self-propelled.

The voltage phase difference applied to the piezoelectric body 3 is + 90 °
And −90 ° are preferable, but a phase difference of several tens of degrees is allowed under the condition that an elliptic locus of displacement is generated at the free end of the vibrating body 2, that is, the process of I, II, III, IV. .

According to the invention of claim 3, claim 1
Alternatively, in the invention according to claim 2, when the phase difference of the voltage applied from the power source section to the piezoelectric body is switched from + 90 ° or a state near it to −90 ° or a state near it, The direction of the elliptical locus of the displacement occurring at the free end is reversed. Therefore, the moving direction of the moving body can be changed.

The condition for changing the moving direction of the moving body is that the in-plane strain grows with time → bend (convex downward) → shrink → bend (convex upward) or stretch → bend (convex upward) → contract → Bending (convex downward) is generated, and it is important that the bending vibration is coupled to the longitudinal vibration. The direction change is determined by the direction of the coupled bending vibration, that is, the priority of upward convex or downward convex.

Specifically, it can be said that the conditions in which the voltage phase difference is + 90 ° and −90 ° are the conditions in which the direction change is most easy. If there are I, II, III, and IV processes, ± 9
A phase difference of tens of degrees is allowed with respect to a phase difference of 0 °. Further, the phase difference before and after the switching when the direction is changed is preferably 180 °, but even within this range, a range of several tens of degrees is allowable.

The ultrasonic actuator of the present invention can be used in OA-related equipment such as a paper feeding device, a card feeding device, a disk driving device such as a CD-ROM, and a read head moving device such as a CD-ROM. In addition, it is suitable for use in a place where a moving distance is within 1 m and linear motion is required under a light load, or in a place where magnetic fields are disliked. Further, it is suitable for the purpose of quietness, small size, light weight, low cost and the like.

[0043]

【Example】

(First Embodiment) A first embodiment of the present invention will be described below with reference to FIGS. 4 and 13 to 15.

As shown in FIG. 13, the elastic body 1 formed in a rectangular cross section (twice the width of the elastic body) that is uniform in the longitudinal direction is formed in the vicinity of the central portion of both opposite surfaces. ,
The vibrating body 2 was constructed by attaching the piezoelectric bodies 3a and 3b so that the polarization directions thereof were opposite to each other. The elastic body 1 was made of steel and had a length of 20 mm, a width of 4 mm, and a thickness of 2 mm. Two
The piezoelectric bodies 3 each had a length of 10 mm, a width of 4 mm, and a thickness of 0.5 mm, and the piezoelectric bodies 3 were attached near the center of the entire length of the elastic body 1 (the arrow indicates the polarization direction of the piezoelectric body).
Since this vibrating body 2 is used as an ultrasonic actuator utilizing a primary longitudinal vibration whose vibration mode is free at both ends, the support pins 6 are provided on both left and right sides at the center of the elastic body 1 in the longitudinal direction.
Was provided. The support pin 6 is fixed to the elastic body 1 by, for example, screwing a male screw portion (not shown) formed at the base end portion thereof into the elastic body 1.

This vibrating body 2 was fixed to a supporting frame (not shown) via both supporting pins 6. The piezoelectric body 3 a attached to the upper surface of the elastic body 1 was connected to the two-phase oscillator 9 via the amplifier 7 and the phase shifter 8. The piezoelectric body 3b attached to the lower surface of the elastic body 1 was connected to the two-phase oscillator 9 via the amplifier 10. The amplifiers 7 and 10, the phase shifter 8 and the two-phase oscillator 9 form a power supply unit. The elastic body 1 was grounded. 2-phase oscillator 9
The output frequency of was set to 131 kHz which is the resonance frequency of the primary longitudinal vibration obtained from the graph of FIG.

First, in order to confirm the principle of the vibrating body 2, it was confirmed whether or not bending vibration occurs when longitudinal vibration is excited. When the phase shifter 8 is set to the piezoelectric body 3a in a state of outputting a voltage with a 90 ° phase advance and the drive frequency is output from the two-phase oscillator 9, the elastic body 1 is in the arrow P direction (longitudinal vibration) and the arrow. The vibration velocity and frequency in the Q direction (bending vibration) were measured with a laser Doppler vibrometer.

As a result, both the P-direction and Q-direction vibrations are 1
It was confirmed that the wavelength was a sine wave with a velocity of about 7.6 μs. The frequency was 131 kHz, which is the same as the driving frequency. Therefore, when the vibrating body 2 is driven by the longitudinal vibration, it can be determined that the bending vibration perpendicular to the central axis is synchronously coupled.

Next, whether the direction of the elliptical locus at the end of the vibrating body 2 changes when the phase difference of the drive voltage is changed is determined by using the upper and lower ends of the vibrating body 2 for laser Doppler vibration. The phase relationship of frequency was investigated with a meter. Voltage phase difference + 90 °
FIG. 14 shows the measurement result when driven with the voltage phase difference of −9.
FIG. 15 shows the measurement results when driven at 0 °. In either case, the results are shown when (a) is the upper end and (b) is the lower end.

When driven at a voltage phase difference of + 90 °, it was confirmed that the vibration speed of the upper end of the vibrating body was advanced by 90 ° with respect to the lower end. It was also confirmed that the upper end of the vibrating body end lags the lower end by 90 ° when driven with a voltage phase difference of −90 °. That is, the phase difference between the vibration velocities at the upper end and the lower end of the vibrating body is both 90 °, and there is a lead and a lag depending on the driving conditions.

The fact that the positional phase difference of the vibration is 90 ° means that the movement of the mass point at the end of the vibrating body 2 is as shown in FIG.
It shows that the locus becomes an elliptical locus as shown in (a) and (b). Further, the fact that the vibration speed has a lead and a lag means that the directions are opposite. When the vibration body 2 is actually excited, a bearing as a moving body is applied to the end of the vibration body 2 and the rotation direction is confirmed. As a result, the rotation occurs when the phase difference is + 90 ° and −90 °. It was confirmed that the direction would change. Further, when a plate-like body is pressed against the end of the vibrating body 2 as a moving body instead of the bearing, the plate-like body is moved in a direction orthogonal to the vibrating body 2 and the phase difference is + 90 ° and −90 °. It was confirmed that the direction of movement changed depending on the case of °. That is, by a simple operation of changing the phase difference of the applied voltage to both A and B phases,
It was confirmed that the moving direction of the moving body could be changed easily.

(Second Embodiment) Next, a second embodiment will be described with reference to FIG. The same parts as those in the above embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

This embodiment is largely different from the above-mentioned embodiment in that a secondary longitudinal vibration with free ends is used as a vibration mode. As shown in FIG. 16, two piezoelectric bodies 3a to 3d are provided on each of the opposite surfaces of the elastic body 1 having a rectangular cross section (the width is twice the thickness of the elastic body). Attached to face each other. The piezoelectric bodies 3a to 3d are
Piezoelectric bodies 3 arranged at opposite and adjacent positions
The polarization directions of a, 3b, 3a and 3c are different from each other. The attachment positions of the piezoelectric bodies 3a to 3d are shown in FIG.
In the vicinity of two nodes of the secondary longitudinal vibration of (a). Elastic body 1
Is made of steel, length 40mm, width 4mm, thickness 2m
m. Similar to the first embodiment, each of the four piezoelectric bodies 3 has a length of 10 mm, a width of 4 mm, and a thickness of 0.5 mm. In order to utilize the secondary longitudinal vibration of which both ends are free as a vibration mode, the support pins 6 are provided at two places near the end portions on both side surfaces of the elastic body 1, that is, four places in total.

Two sets of piezoelectric bodies 3a, 3 having the same polarization direction and attached at diagonally opposite positions with the elastic body 1 sandwiched therebetween.
The first set of piezoelectric bodies 3a and 3d of d, 3b and 3c were connected to the two-phase oscillator 9 through the amplifier 7 and the phase shifter 8 as the A phase. The piezoelectric bodies 3b and 3c of the second set were connected to the two-phase oscillator 9 via the amplifier 10 as the B phase.

The resonance drive frequency of the secondary longitudinal vibration corresponding to the length and vibration mode of the vibrating body 2 is obtained from the graph of FIG. 4, and the output frequency of the two-phase oscillator 9 is set to the value (the same 131 kHz as in the first embodiment). ), And vibrating body 2 was excited. Then, with the voltage phase difference of ± 90 ° being applied to the A and B phases, the bearing was pressed against the end portion of the vibrating body 2 and the rotation direction thereof was confirmed. As a result, the same result as that of the first embodiment was obtained. Also, when a plate-shaped moving body is pressed against the first
The same result as the example was obtained.

Also, as shown in FIG. 17, the same applies when the piezoelectric bodies 3a and 3c attached to the upper surface of the elastic body 1 are in the A phase and the piezoelectric bodies 3b and 3d attached to the lower surface are in the B phase. The same examination was conducted by exciting at the driving frequency. Also in this case, the same results as when the piezoelectric bodies 3a and 3d were in the A phase and the piezoelectric bodies 3b and 3c were in the B phase were obtained. That is, when the same vibration mode is used, if the elastic bodies 1 are the same, even if the arrangement of the piezoelectric bodies is different, the same behavior can be obtained when a voltage corresponding to the resonance drive frequency is applied to each piezoelectric body with a predetermined phase difference. Was confirmed.

(Third Embodiment) Next, a third embodiment will be described. In this embodiment, the width of the elastic body 1 is changed to 8 mm (width is 4 times the thickness of the elastic body), and all other conditions are the second.
The same examination was carried out as in the example. as a result,
Almost the same result as the second embodiment was obtained. Also, the elastic body 1
The same examination was carried out when the cross-sectional shape of the rectangular shape was such that both ends in the longitudinal direction of the rectangle were arcuate, as shown in FIGS. 5 (d) and 5 (e). As a result, almost the same result as the second embodiment was obtained.

That is, almost the same result was obtained regardless of the cross-sectional shape of the elastic body 1, so that longitudinal vibration can be excited regardless of the cross-sectional shape of the elastic body (vibrating body), and at the same time bending vibration is coupled. I was able to support what I did. Further, even if the ratio of the dimension in the width direction to the dimension in the thickness direction was 8/2 (4 times), almost the same result was obtained. Therefore, the preferable width in the case of a flat rod-shaped vibrating body is It was confirmed that even about 4 to 5 times was acceptable.

(Fourth Embodiment) Next, a fourth embodiment will be described. In each of the above-described embodiments, the vibrating body is fixed and the moving body is moved (including rotation), but in this embodiment, the vibrating body itself is moved (self-propelled). It is very different from the example.

As shown in FIG. 18, protrusions 11 are provided downward at both front and rear ends of the elastic body 1 constituting the vibrating body 2. The size of the vibrating body 2 in this case is the same as that of the second embodiment, and the height of the protrusion 11 is 3 mm and the width is 2 mm.
Were provided at both ends. The other structure is the same as that of the vibrating body 2 of the second embodiment. A pair of guide frames 13 (shown by chain lines) are provided on the running surface 12 of the vibrating body 2 at intervals wider than the width of the vibrating body 2.
a is formed to extend along the traveling surface 12.
The vibrating body 2 is supported by the guide frame 13 in a state where the support pin 6 is slidably inserted into the guide hole 13a and the tip of the protrusion 11 is pressed against the traveling surface.

When the vibrating body 2 vibrates at its end (end face) with an elliptic locus of displacement, similar elliptical loci are confirmed on the upper and lower surfaces of the end. For example, the vibrating body 2 using the secondary longitudinal vibration mode of which both ends are free as in the second embodiment.
Then, as shown in FIG. 19, the direction of the elliptic locus of displacement is
The same applies to both end faces of the vibrating body 2 and both upper and lower end faces. The direction is opposite between the case where the phase difference shown in FIG. 19A is + 90 ° and the case where the phase difference shown in FIG. 19B is −90 °.

Therefore, the piezoelectric bodies 3a to 3d of the A and B phases are +
When the vibrator 2 is excited by applying a voltage phase difference of 90 °,
The movement of the mass point at the tip of the protrusion 11 is as shown in FIG.
It becomes a clockwise elliptic locus, and the vibrating body 2 advances to the right side of FIG. In addition, the piezoelectric bodies 3a to 3d of the A and B phases have a -90
When the vibrating body 2 is excited by applying a voltage phase difference of °, the direction of the elliptical locus is reversed and the vibrating body 2 advances to the left side in FIG. That is, a self-propelled structure can be achieved by merely providing the protrusions 11 on both ends of the vibrating body 2. Further, the phase difference of the applied voltage to the piezoelectric bodies 3a to 3d of the A and B phases is + 90 ° and −.
By switching to 90 °, the traveling direction can be easily changed. Note that, as shown in FIG.
From the viewpoint of stable driving of vibration, the protrusions 11 may be provided on both upper and lower surfaces of both ends of the elastic body 1. When the projections 11 are provided on the upper and lower surfaces, when the projection 11 on one side is worn due to long-term use, the vibrator 2 can be used again only by turning it over. Further, instead of the metal protrusion 11, a lining material may be attached to the elastic body 1.

In order to use the displacement of both ends of the vibrating body to form a self-propelled structure, the directions of the elliptical loci of the displacements of both ends of the vibrating body must be the same. Limited to using vertical vibration mode.

(Fifth Embodiment) Next, a fifth embodiment will be described. This embodiment is largely different from the fourth embodiment in that the vibrating body itself is moved using the end face of the vibrating body. As shown in FIG. 21, the vibrating body 2 is composed of an elastic body 1 having a length suitable for use in the primary longitudinal vibration mode and piezoelectric bodies 3a and 3b attached to both surfaces thereof. A plurality of vibrating bodies 2 are connected to each other via a connecting bar 14 in a state of extending in the vertical direction in parallel with each other. Both piezoelectric bodies 3
The a and 3b are formed so that their polarization directions are different from each other. The vibrating body 2 is placed on the traveling surface 12 in a state where the first end side of each vibrating body 2 is in contact with the traveling surface 12, and an applied voltage having a phase difference of, for example, + 90 ° is applied from a power source unit (not shown). When supplied and excited, an elliptical locus of displacement in the same direction (clockwise in FIG. 21) is generated at the first end of each vibrating body 2. As a result, the vibrating body 2 moves to the right in FIG. When excitation is performed using an applied voltage having a phase difference of −90 °, the directions of the elliptical loci become opposite and the vibrating body 2 moves to the left.

In this system, that is, in the system in which a plurality of vibrators 2 are connected in parallel and the end faces of the vibrators 2 are brought into contact with the running surface 12 to excite them, the vibration modes are primary and secondary longitudinal vibration modes. Any of the above is possible.

The present invention is not limited to the above embodiments, but may be embodied as follows. (1) As shown in FIG. 22, the plurality of vibrating bodies 2 are arranged so that one end face of each vibrating body 2 is located on the same plane, and the moving body 4 is moved. Since each vibrating body 2 is small, this configuration is suitable when increasing the moving distance of the moving body 4.

(2) Instead of the self-propelled vibrating body 2 which uses the displacement of the projection 11 or the lining material provided at the end of the elastic body 1 as in the fourth embodiment, the vibrating body 2 is fixed. Alternatively, the moving body may be moved. In this case, if the plurality of vibrating bodies 2 are arranged in a straight line in the longitudinal direction, the moving body can be moved by the same distance with a smaller number of vibrating bodies 2 than in the case of (1).

(3) The vibrating body 2 provided with the protrusions 11 on both upper and lower surfaces of both ends of the elastic body 1 is used in the secondary longitudinal vibration mode in which both ends are free, and as shown in FIG. It may be used as an actuator of 15. In this case, one actuator can drive two drive pulleys 16
Can be driven synchronously.

(4) In each of the above-mentioned embodiments and the like, the vibrating body 2 is used with both ends free, but it may be used with one end fixed and the other end free. When the vibrating body 2 is used with one end fixed and the other end free, the first end of the vibrating body 2 is fixed to the support portion. As a fixing method, for example, there is a method of fixing the end surface of the vibrating body 2 to a support portion with an adhesive or the like, and a method of screwing a bolt into a screw hole formed in the end surface of the vibrating body 2.

Even if the material and the length of the vibrating body 2 are the same, the resonance drive frequency is different from the case where both ends are free. Therefore, the proper resonance drive frequency is obtained from the graph corresponding to FIG. Is applied to each piezoelectric body with a predetermined phase difference. In this case, since only the displacement on the free end side can be used, the degree of freedom in designing the actuator becomes smaller than that in the case where both ends are free. When the vibrating body 2 is used in a self-propelled configuration, the first end faces of the plurality of vibrating bodies 2 are fixed to the connecting bar to have a configuration similar to that of the fifth embodiment.

(5) The vibration mode is used as a method for changing the moving direction of the moving body when it is used as a fixed actuator or for changing the moving direction of the mover when it is used as a mover (self-propelled structure). You may change it.
When the same vibrating body 2 is excited in the primary longitudinal vibration mode,
Since the direction of the elliptical locus of displacement at the end is opposite to that in the case of exciting in the secondary longitudinal vibration mode, it is possible to change the moving direction by changing the use mode.
That is, instead of changing the phase difference of the applied voltage to the piezoelectric body, the moving direction is changed by switching the frequency of the applied voltage between the resonance frequency in the primary mode and the resonance frequency in the secondary mode. Therefore, an oscillator whose oscillation frequency can be changed is used as the power supply unit, and the phase shifter 8 is omitted.

When the vibration mode is changed, the amount of displacement at the end face of the vibrating body 2 is different, so that the operating characteristic changes depending on the vibration mode. As a result, for example, FIG.
As shown in, when a rotating body is used as the moving body 4,
It is difficult to obtain the same characteristics depending on the rotation direction. Therefore, it is preferable to fix the vibration mode and change the moving direction of the moving body or the like by changing the phase difference of the applied voltage because the same characteristics can be obtained regardless of the moving direction.

Inventions other than those described in the claims that can be grasped from the respective embodiments and modifications will be described below together with their effects. (1) In the invention according to any one of claims 1 to 3, a rod-shaped vibrating body as a vibration generating part is used in a vibration mode in which both ends are free. In this case, the degree of freedom in use as an actuator, that is, the degree of freedom in design, is greater than in the case of using the vibration mode in which one end is fixed and the other end is free.

(2) Protrusions are provided at both ends of the rod-shaped vibrating body as the vibration generating portion in the inventions of claims 1 to 3, and the vibrating body is oriented so that the protuberances are directed upward and both ends are free. A plurality of transfer devices arranged along the longitudinal direction of the transfer device for use in the secondary longitudinal vibration mode. In this case, it is possible to reduce the number of actuators of the unit unit required to move the moving body over a long distance.

[0074]

As described in detail above, according to the invention described in claims 1 to 3, the vibration is caused by vibrating the vibrating body with the applied voltage of the same resonance frequency of the longitudinal vibrations having different phase differences. Since an elliptical locus of displacement occurs at the free end of the body,
It is possible to obtain an ultrasonic actuator that does not require a complicated vibration system and has a large degree of freedom in the shape and dimensions of the vibrating body, that is, a large variation.

According to the second aspect of the invention, the vibrating body constituting the vibration generating section is a flat rod-shaped elastic body.
Since the piezoelectric body is composed of two piezoelectric elements that are arranged to face each other in the thickness direction, the degree of freedom in manufacturing the vibrating body is increased.

According to the third aspect of the invention, the moving direction of the moving body can be easily changed with a simple structure in which the phase difference of the voltage applied to the piezoelectric body is switched at ± 90 ° or in the vicinity thereof. Becomes

[Brief description of drawings]

FIG. 1 is a diagram showing boundary conditions and vibration modes of a rod-shaped elastic body.

FIG. 2 is a schematic view of a rod-shaped vibrating body with free ends and free ends when longitudinal vibration is excited.

FIG. 3 is a schematic diagram of a rod-shaped vibrating body with free ends and free ends when bending longitudinal vibration is excited.

FIG. 4 is a diagram showing the relationship between the resonance frequency and the length of a straight rod-like elastic body that is made of steel and is straight and not too thick.

FIG. 5 is a sectional view showing the vicinity of a rod-shaped elastic body to which a piezoelectric body is attached.

FIG. 6A is a schematic perspective view showing a configuration of a vibrating body,
(B)-(d) is a schematic side view similarly.

7A to 7C are schematic side views showing the arrangement of piezoelectric bodies, and FIGS. 7D to 7E are schematic perspective views.

FIG. 8 is a schematic diagram of a vibrating body.

FIG. 9 is a waveform diagram of a drive voltage applied to the A-phase and B-phase piezoelectric bodies of the vibrating body.

FIG. 10 is a schematic diagram showing changes in both ends of the vibrating body when the B phase is applied with a phase difference of 90 ° with respect to the A phase.

FIG. 11 is a schematic diagram showing a locus of a mass point at an end portion of a vibrating body.

FIG. 12 is a schematic diagram showing an arrangement of an end portion of a vibrating body and a moving body.

FIG. 13 is a schematic configuration diagram of an ultrasonic actuator (vibrating body) according to the first embodiment.

FIG. 14 is a diagram showing a drive voltage waveform and a vibration speed at the end of the vibrating body when the angle advances by 90 °.

FIG. 15 is a diagram showing a drive voltage waveform and a vibration velocity at the end of the vibrating body when the delay time is 90 °.

FIG. 16 is a schematic configuration diagram of an ultrasonic actuator (vibrating body) according to a second embodiment.

FIG. 17 is a schematic configuration diagram when the wiring connection of the second embodiment is changed.

FIG. 18 is a schematic diagram of an ultrasonic actuator according to a fourth embodiment.

FIG. 19 is a schematic diagram showing the orientation of an elliptical locus at the end of the vibrating body.

FIG. 20 is a schematic perspective view showing a modified example of the vibrator protrusion.

FIG. 21 is a schematic diagram of an ultrasonic actuator according to a fifth embodiment.

FIG. 22 is a schematic view of an ultrasonic actuator of a modified example.

FIG. 23 is a schematic view of an ultrasonic actuator according to another modification.

FIG. 24 is a schematic view of a conventional ultrasonic actuator.

FIG. 25 is a schematic view showing directions of vibration and displacement of standing waves.

FIG. 26 is a schematic perspective view showing another conventional vibration body and an elliptical locus of displacement.

27A is a schematic perspective view of another conventional ultrasonic motor, and FIG. 27B is a plan view of a vibrating body.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Elastic body, 2 ... Vibrating body as a vibration generation part, 3, 3a
˜3d ... Piezoelectric body, 7, 10 ... Amplifier constituting power supply section,
8 ... Also a phase shifter, 9 ... A two-phase oscillator.

Claims (3)

[Claims] 1. A vibration generating part, which is a rod-shaped body provided with a piezoelectric body configured such that at least one end is supported in a free state and a plurality of polarizations having different polarization directions are present, and an axial direction of the rod-shaped body. In order to generate longitudinal vibration and bending vibration, a power supply unit for applying a resonance drive voltage of longitudinal vibration to the piezoelectric body is provided, and the axial length of the rod-shaped body resonates with the longitudinal vibration and vibrates at its free end. The abdomen is present, and the power source unit, in order to generate an in-plane strain due to axial extension and contraction in the vibration generating unit, the movement of the mass of the free end of which becomes an elliptical locus. An ultrasonic actuator, wherein a voltage having a phase difference can be applied. 2. The super vibrating body according to claim 1, wherein the vibration generating portion is a vibrating body including a flat rod-shaped elastic body and piezoelectric bodies arranged on both sides or one side of two surfaces facing each other in a thickness direction thereof. Sonic actuator. 3. The ultrasonic actuator according to claim 1, wherein the power source unit is capable of switching a phase difference of voltages applied to the piezoelectric body within ± 90 ° or in the vicinity thereof.