JPH0638557A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To provide a new ultrasonic motor, in which not traveling wave but standing wave is generated in the rotor contact surface of a stator part to rotate a rotor part. CONSTITUTION:The ultrasonic motor has a flat-shaped stator part 100 and a rotor part 200 driven by rotation in a predetermined direction. The stator part 100 contains an oscillating elastic body 30, a piezoelectric element 10 and a plurality of projections 32 formed in a rotor contact surface 110. Then, AC voltage is applied to the voltage application region of the piezoelectric element 10 so that standing wave is generated in the rotor contact surface 110. When the projections 32 are provided between the antinode and node of the standing wave, an elliptic oscillation is generated in the projections 32 so that the rotor part 200 in contact with the projections 32 is driven by rotation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor, and more particularly to an ultrasonic motor which drives a rotor portion by a standing wave generated on a rotor contact surface.

[0002]

2. Description of the Related Art An ultrasonic motor converts an oscillating motion generated when a voltage such as an alternating current is applied to a piezoelectric element into a rotary motion or a one-dimensional motion. Compared with the conventional electromagnetic motor, it does not require windings, so it has the advantages of simple structure and small size, and high torque even at low speed rotation.

Generally, an ultrasonic motor is composed of a rotor portion which is a moving body, a stator portion which is a vibrating body, and a support member which supports the stator portion.

Among them, the stator portion is formed in a flat and thin shape by bonding a piezoelectric body such as PZT (lead zirconate titanate) to a vibration elastic body made of copper alloy or the like.
Usually, this piezoelectric body is divided into a large number of pieces, which are alternately polarized in positive and negative directions, and two sets of electrode groups are provided correspondingly.
By applying a voltage of a resonance frequency having a 90 ° phase difference in time to these two sets of electrodes, two standing waves are combined and a plurality of moving waves are moved in the circumferential direction at a constant speed with time. A traveling wave with peaks is excited on the rotor contact surface. Therefore, by bringing the rotor portion into contact with the rotor contact surface of the stator portion, the rotor portion is rotationally driven in the predetermined direction.

As a flattened thin type ultrasonic motor of this type, a proposal according to Japanese Patent Laid-Open No. 59-201685 is known. In particular, in the ultrasonic motor according to this proposal, the moving speed of the rotor part is increased by forming the surface of the vibrating elastic body forming a part of the stator part into a large number, and an ultrasonic motor with high drive efficiency is realized. Is possible.

[0006]

However, in the conventional flat and thin ultrasonic motors, there are those that rotationally drive the rotor portion by the traveling wave, but none that rotationally drive the rotor portion by the standing wave. .

An object of the present invention is to provide a new ultrasonic motor for generating a standing wave, not a traveling wave, on the rotor contact surface of the stator part, and thereby rotating the rotor part.

[0008]

To achieve the above object, the present invention comprises a flat stator portion and a rotor portion which is pressed against a rotor contact surface of the stator portion and driven in a predetermined direction. In the ultrasonic motor, the stator portion is provided on a vibrating elastic body having a rotor contact surface formed on the front surface side and a back surface side of the vibrating elastic body, and a plurality of voltage application regions are provided along the moving direction of the rotor portion. The rotor contact surface includes a formed piezoelectric element and a plurality of protrusions formed on the rotor contact surface along the rotor moving direction, and by applying an AC voltage to the voltage application region of the piezoelectric element, the rotor contact surface is formed. By generating a standing wave on the surface and providing the protrusion between the antinode and the node of the standing wave, elliptical vibration is generated in the protrusion, and the rotor portion in contact with the protrusion is moved. And

[0009]

In the present invention, a plurality of voltage application regions are formed on the surface of the piezoelectric element along the moving direction of the rotor section. Moreover, the vibrating elastic body is formed in a flat shape so that bending vibration caused by bending of the beam is generated by vibration of the piezoelectric element. Therefore, by applying an AC voltage to the plurality of voltage application regions, a standing wave due to the bending of the beam is generated on the rotor contact surface of the stator part. In particular, in the present invention, since the protrusion is provided between the antinode of the standing wave and the node, elliptical vibration is directly generated on the end surface of the protrusion by the standing wave, and the rotor unit can be driven. .

As described above, in the ultrasonic motor of the present invention,
Unlike conventional ultrasonic motors, elliptical vibration due to standing waves can be directly generated on the rotor contact surface to drive the rotor portion to rotate.

In addition to this, in the invention of claim 2, the piezoelectric element selectively switches between the first standing wave and the second standing wave having different phases on the rotor contact surface by switching the applied AC voltage. It is formed to occur in The plurality of protrusions are located between the antinode of the first standing wave and the node on one side, and are located between the antinode of the second standing wave and the node on the other side. Is formed.

Therefore, the drive direction of the rotor portion in contact with the protrusion can be switched by controlling the switching of the applied AC voltage and selecting the standing wave to be generated.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the drawings.

First Embodiment FIG. 2 shows an outline of an annular ultrasonic motor according to the first embodiment of the present invention. The ultrasonic motor of the embodiment includes a flat and thin stator portion 100 having a ring shape, and a rotor portion 200 which is rotationally driven by ultrasonic vibration generated on a rotor contact surface 110 of the stator portion. In addition, in the same figure, in order to make the structure of the stator part 100 easy to understand, the rotor part 200 is shown with a part thereof cut away.

First, the stator 100 will be described.

FIG. 3 schematically shows an exploded perspective view of the stator 100. Example Stator Unit 10
Reference numeral 0 has a piezoelectric element 10 formed in a ring shape by using a piezoelectric body such as ceramics, and a ring-shaped vibrating elastic body 30 laminated on one side of the piezoelectric element 10, and both are adhesive. It is fixed integrally via.

The piezoelectric element 10 generates a mechanical ultrasonic wave by applying a voltage. On the surface side of the piezoelectric element 10 of the embodiment, as shown in FIG.
Twelve surface electrodes 20-1 and 20-2 along the rotation direction of 00.
0-12, ..., 20-12 are formed by coating silver, nickel, or the like, for example. Further, on the back surface side of the piezoelectric element 10, as shown in FIG.
-1,22-2,22-3,22-4 are similarly coated. The five electrodes 20-1, 20-2, ..., 20-5 formed at equal intervals face the electrode 22-1 on the back side of the piezoelectric element 10 with the piezoelectric element 10 in between, and similarly. Five electrodes 20-7, 20- formed at equal intervals
8 ... 20-11 are opposed to the electrode 22-3 on the back surface side of the piezoelectric element 10 via the piezoelectric element 10. Furthermore, the electrode 20-
6, 20-12 are opposed to the electrodes 22-2, 22-4 formed on the back surface side of the piezoelectric element 10.

Using the electrodes coated as described above, as shown in FIG. 4, the piezoelectric element 10 of the embodiment has 12 polarization regions 12- on its surface side along the rotor rotation direction.
1, 12-2, ... 12-12 are formed. The adjacent polarizations are formed such that their polarization directions are different from each other. It should be noted that in the figure, the symbols "+" and "-" indicate the polarization directions of the piezoelectric element. The five regions 12-1, 12-2, ... 12-5 polarized at equal intervals are used as the polarization regions of the A phase, and 12-7, 12-8, ... The five polarization regions 12-11 are used as B-phase polarization regions, and the polarization regions 12-6 and 12-12 located between the A-phase and B-phase polarization regions are used as feedback polarization regions. .

The vibrating elastic body 30 is formed of, for example, a copper alloy so that the ultrasonic vibration generated in the piezoelectric element 10 can be efficiently transmitted and vibrated. Then, the phase A polarized regions 12-1, 12-2, ... 12 of the piezoelectric element 10
-5 or B phase polarized region 12-7, 12-8, ... 12
By applying a predetermined single-phase AC voltage to −11, a standing wave is generated on the rotor contact surface 110 of the vibrating elastic body 10. At this time, information such as the frequency and the amplitude of the vibration generated in the piezoelectric element 10 is used as feedback polarization regions 20-6 and 22-2 and 20-12 and 22-4.
And is used as a feedback signal.

The rotor contact surface 110 of the vibrating elastic body 30.
A plurality of protrusions 32 are provided on the top of the rotor along the rotation direction of the rotor unit 200.

Each of the protrusions 32 is formed at an intermediate position between the antinode and the node of the standing wave, converts the standing wave generated on the rotor contact surface 110 into elliptical vibration, and contacts the protrusion 32 with the rotor portion. It is configured to rotationally drive 200. In the embodiment, since a standing wave of 6 wavelengths is generated on the rotor contact surface 110, a total of 12 of the plurality of protrusions 32 are formed at the intermediate position between the antinode of the standing wave and the node.

Next, the rotor section 200 will be described.

As shown in FIG. 2, the rotor portion 200 is
A ring 50 and a friction material 52 adhered and fixed to the stator contact surface of the ring 50 are formed, and the friction material 52 is formed so as to come into contact with the protrusion 32 provided on the front surface side of the vibration elastic body 30 with a predetermined pressure. Has been done. Therefore, the driving force by the elliptical vibration of the ultrasonic waves generated on the surface of the vibrating elastic body 30 is efficiently transmitted to the rotor unit 200 by the friction material 52, and the rotor unit 200 is rotationally driven in the predetermined direction.

Next, the positional relationship between the standing wave generated on the rotor contact surface 110 and the protrusion 32 will be described.

FIG. 1 schematically shows the structure of the ultrasonic motor of the embodiment.

FIG. 1A is a schematic view of the stator portion 100 developed in the circumferential direction. The symbol "+" indicates a region (a positive polarization region of the piezoelectric element 10) extending when the applied AC voltage is positive. And the symbol “−” indicates a region that contracts when the potential of the applied AC voltage is positive (corresponding to the − polarized region of the piezoelectric element 10).

FIG. 1B shows the rotor contact surface 110 of the stator portion 100 when a single-phase AC voltage is applied to the A-phase polarized regions 12-1, 12-2, ... 12-5 of the piezoelectric element 10. The state of vibration of is shown. As shown in the figure, when a single-phase AC voltage is applied to the A-phase polarization regions 12-1, 12-2, ... 12-5, a first standing wave is generated.

FIG. 3C shows the rotor contact surface 110 of the stator portion 100 when a single-phase AC voltage is applied to the B-phase polarized regions 12-7, 12-8, ... 12-11 of the piezoelectric element 10. The state of vibration of is shown. As shown in the figure, the B-phase polarization regions 12-7, 12-8, ... 12-11
When a single-phase AC voltage is applied to the second standing wave, a second standing wave is generated.

As shown in FIGS. 2B and 2C, in the stator portion 100 of the embodiment, a single-phase AC voltage is applied to the A-phase polarization region and a single-phase AC voltage is applied to the B-phase polarization region. The rotor contact surface 110 of the stator part 100
First and second standing wave vibrations having different phases are generated above. According to the study by the present inventor, it is estimated that this standing wave is generated by bending vibration due to bending of the beam caused by vibration of the piezoelectric element 10.

The protrusion 32 of this embodiment is located between the antinode of the first standing wave shown in FIG. 1 (B) and the node on the right side thereof, and the second protrusion shown in FIG. 1 (C). It is formed so as to be located midway between the antinode of the standing wave and the node on its left side.

The embodiment has the above construction, and its operation will be described below.

Using the vibration motor of the embodiment, the rotor unit 20
When 0 is normally driven, a single-phase AC voltage is applied to the A-phase polarization regions 12-1, 12-2, ... 12-5 of the piezoelectric element 10. As a result, the first standing wave ultrasonic vibration as shown in FIG. 1B is generated on the rotor contact surface 100 of the stator portion 100. At this time, 90 ~ of the first standing wave
The protrusions 32 of the group located in the middle of 180 degrees are arranged in the rotor portion 200 when the area A of the stator portion 100 extends.
Is pushed out in the right direction in the figure, and when contracted, it is separated from the rotor unit 200. Then, when the area A of the stator section 100 contracts, the protrusions 32 of the other group located in the middle of 270 to 360 degrees of the first standing wave are transferred to the rotor section 20.
It acts to push 0 to the right in the figure. 2 like this
The protrusions 32 of one group are alternately operated,
00 is driven to rotate rightward in the figure.

When the rotor portion 200 is driven in the reverse direction, the B-phase polarized regions 12-7, 12- of the piezoelectric element 10 are driven.
It is sufficient to apply a single-phase AC voltage to 8, ... 12-11. As a result, the stator portion 100 may be configured as shown in FIG.
The second standing wave ultrasonic vibration as shown in (C) is generated. At this time, the protrusions 32 of the group positioned in the middle of 270 to 360 degrees of the second standing wave are the stator portions 100.
When the area B is extended, it acts to push the rotor portion 200 leftward in the drawing, and when it is contracted, the rotor portion 20 is pushed out.
Move away from zero. Then, when the B region of the stator part 100 contracts, the protrusions 32 of the other group located in the middle of 90 to 180 degrees of the second standing wave act to push the rotor part 200 leftward in the drawing. To do. In this way, the protrusions 32 of the two groups alternately operate to drive the rotor unit 200 to rotate leftward in the drawing.

As described above, according to the ultrasonic motor of the embodiment, it is possible to drive the rotor portion 200 in the normal rotation and the reverse rotation only by switching the polarization region to which the single-phase AC voltage is applied. FIG. 6 shows a control circuit of the ultrasonic motor of the embodiment.

This control circuit has two single-phase AC voltages A,
A power supply circuit 90 that selectively outputs B and an amplifier 92 that amplifies this single-phase AC output and applies it to the A-phase polarized region or the B-phase polarized region of the piezoelectric element 10 are included.

The control circuit also includes an ON / OFF switch 82, a rotation direction input section 86 and a rotation speed input section 8.
Including 8.

The ON / OFF switch 82 controls ON / OFF of the power supply circuit 90 and the amplifier 92.

The rotation direction input section 86 is the rotor section 20.
This is for selectively setting the rotation direction of 0, and this output signal is input to the power supply circuit 90. The power supply circuit 90 is
Based on this input signal, the single-phase AC voltage A applied to the A-phase polarized regions 12-1, 12-2, ... 12-5 of one group, or the B-phase polarized region 12- of the other group 12-
Single phase AC voltage B applied to 7, 12-8, ... 12-11
Only one of the two is selected and output. Thereby, the rotation direction of the rotor unit 200 can be set. The rotation speed input unit 88 can set the rotation speed of the rotor unit 200 by controlling the amplification factor of the amplifier 92.

Further, in the embodiment, since the single-phase AC voltage output from the power supply circuit 90 is set to the resonance frequency corresponding to the resonance mode of the stator section 100, the input voltage is efficiently converted into the rotation output. The rotor unit 200 can be rotationally driven.

In the above embodiment, the case where the rotor portion 200 is rotationally driven in both directions has been described as an example. However, when the rotor portion 200 is rotationally driven only in one direction, the stator portion is shown in FIG. It may be formed as shown.

That is, the phase A polarization region 1 of the piezoelectric element 10
2-1, 12-2, ... 12-5 and feedback polarization regions 12-6, 12-12 are polarized as in the first embodiment, and B-phase polarization regions 12-7, 12- are formed.
No polarization treatment is applied to 8 ... 12-11.

With the above-mentioned structure, by applying a single-phase AC voltage to the A-phase polarization regions 12-1, 12-2, ... 12-5, the same as in the first embodiment, The rotor unit 200 can be rotationally driven in the forward direction.

Second Embodiment FIG. 8 shows a second preferred embodiment of the present invention.
The basic structure of the ultrasonic motor of the embodiment is the same as that of the first embodiment except the arrangement of the protrusions 32 provided on the rotor contact surface 110. Therefore, only the characteristic part will be described here, and the other description will be omitted.

The feature of this embodiment is that by applying an AC voltage to the entire surface of the piezoelectric element 10, the entire area of the stator section 100 is vibrated and the output of the rotor section 200 is increased. That is, in the first embodiment, when the A region of the stator part 100 is vibrated, the B region is in a rest state, and when the B region is vibrated, the A region is in a rest state. Therefore, at the time of driving, the stator portion 10 is always
In this embodiment, the driving efficiency is improved because half of the area is 0.

FIG. 8A shows the stator portion 10 of the embodiment.
A schematic view of 0 deployed in the circumferential direction is shown.

FIG. 2B shows a standing wave generated on the rotor contact surface 110 when the A-phase single-phase AC voltage is applied to the A-phase polarized regions 12-1 to 12-5 of the piezoelectric element 10. A state of vibration is shown, and in the same figure (C), the B-phase polarized region 12-7 is shown.
The solid line shows the state of the standing wave vibration that occurs when a B-phase single-phase AC voltage of the same phase as the A-phase is applied to ~ 12-11. The state of standing wave vibration when applied is shown by a broken line.

Further, FIG. 3D shows the rotor contact surface 110 when the A-phase and B-phase AC voltages are simultaneously applied.
The state of the synthetic vibration appearing in is shown. This is a superposition of the vibration waveforms shown in FIGS.

Further, in FIG. 6E, when the A-phase and B'-phase AC voltages are simultaneously applied, the rotor contact surface 1
The state of the synthetic vibration appearing in 10 is shown. this is,
The vibration waveform shown in FIG. 7B and the vibration waveform shown by a broken line in FIG.

In the present embodiment, each protrusion 32 is shown in FIG.
It is located between the antinode of the first standing wave shown in (D) and the node on the right side thereof, and is located between the antinode of the second standing wave shown in FIG. 8 (E) and the node on its left side. Is formed.

Next, the operation of this embodiment will be described.

A-phase polarized regions 12-1 to 1 of the piezoelectric element 10
2-5 and B phase polarized regions 12-7 to 12-11, A
When the single-phase AC voltages of the B-phase and the B-phase are simultaneously applied, the first standing wave vibration shown in FIG. 3D is generated on the rotor contact surface 110 of the stator section 100. At this time,
Since the protrusion 32 is located between the antinode of the first standing wave and the node on the right side of the first standing wave, the rotor portion 200 is provided on the end face of the protrusion 32.
Elliptical vibration is generated such that the rotation is driven to the right in the figure.

Further, the A-phase polarized region 12- of the piezoelectric element 10
1-12-5 and B-phase polarized regions 12-7-12-11
When the A-phase and B′-phase single-phase AC voltages are simultaneously applied to the second and the second, the second standing wave vibration shown in FIG. 8E is generated. At this time, since the protrusion 32 is located between the antinode of the second standing wave and the node on the left side of the second standing wave, the end face of the protrusion 32 has an elliptical vibration in the direction opposite to that in FIG. 8D. When the rotor portion 200 is generated, the rotor portion 200 is driven to rotate leftward in the drawing.

In particular, according to this embodiment, as compared with the first embodiment, the entire area of the stator portion 100 (both the area A and the area B) is vibrated at the same time to drive the rotor portion 200 to rotate. A larger output torque can be obtained as compared with the first embodiment.

The specific structure of the control circuit of the ultrasonic motor of the embodiment is almost the same as that shown in FIG.
The power supply circuit 90 can simultaneously output two AC voltages having the same phase (A phase and B phase) or two AC voltages having opposite phases (A phase, B ′ phase) at the same time. These two outputs are selected by the rotation direction input unit 8
It is to be instructed by 6.

Third Embodiment Next, a preferred third embodiment of the present invention will be described. In this embodiment, the basic structure other than the polarization structure of the piezoelectric element 10 and the arrangement of the protrusions 32 is the same as that of the first embodiment, and therefore only the characteristic part will be described here. Other description is omitted.

FIG. 9 shows the polarization structure of the surface of the piezoelectric element 10 used in the ultrasonic motor of this embodiment.
The piezoelectric element 10 of the embodiment has 30 ° along its circumferential direction.
12 polarization regions 12-1, 12-, which are divided into 12 equal parts for each
2 ... 12-12, and two adjacent regions are set as a pair of polarization regions. Then, the two regions forming each set are polarized to the same polarity, one polarization region forming an A phase polarization region and the other region forming a B phase polarization region.

Further, the polarization regions of each pair adjacent to each other are formed so that their polarization directions are opposite to each other.

Then, as shown in FIG. 10A, on the surface side of the piezoelectric element 10 of the embodiment, the A-phase AC voltage is in the A-phase polarization region and the B-phase AC voltage is in the B-phase polarization region. Surface electrodes 20-1, 20-2, ...
20-12 are formed. Further, as shown in FIG. 10B, a common surface electrode 22 is formed on the entire back surface of the piezoelectric element 10 of the example.

These surface electrodes 20-1, 20-2, ...
20-20 and 22 are the same as those used when the piezoelectric element 10 is polarized.

FIG. 11A schematically shows a state in which the ultrasonic motor of the embodiment is developed in the circumferential direction. When the A-phase AC voltage is applied to the piezoelectric element 10 of this ultrasonic motor, the rotor contact surface of the stator section 100 is exposed as shown in FIG.
The first standing wave vibration shown in (B) is generated. When a B-phase AC voltage is applied to the piezoelectric element 10, the stator section 1
On the rotor contact surface 110 of No. 00, the second standing wave vibration shown in FIG.

In the present embodiment, each protrusion 32 has a structure as shown in FIG.
It is located in the middle of the antinode of the first standing wave shown in FIG. 1 (B) and the node on the right side thereof, and in the middle of the antinode of the second standing wave shown in FIG. 11 (C) and the node on the left side thereof. Is formed.

As a result, when the A-phase AC voltage is applied to the A-phase polarized region of the piezoelectric element 10, the end face of the protrusion 32 is
The elliptical vibration shown in FIG.
Will be driven to rotate in the right direction in the figure.

Conversely, when a B-phase AC voltage is applied to the B-phase polarized region of the piezoelectric element 10, elliptical vibration shown in FIG.
Will be driven to rotate leftward in the figure.

When the ultrasonic motor of the embodiment is formed as a one-way rotating type, as shown in FIG. 12, only the A-phase polarized region of the piezoelectric element 10 is polarized as in FIG. It is not necessary to perform any polarization treatment on the region corresponding to the phase polarization region.

Fourth Embodiment FIG. 13 shows a preferred fourth embodiment of the present invention. The ultrasonic motor of this embodiment has the same basic configuration as that of the third embodiment shown in FIG. 11 except the arrangement of the plurality of protrusions 32 provided on the rotor contact surface 110. Here, only the characteristic part will be described, and the other description will be omitted.

The feature of this embodiment resides in that the entire area of the stator portion 100 is vibrated by applying an AC voltage to the entire area of the piezoelectric element 10. That is, in the third embodiment, when the area A of the stator part 100 is vibrated, the area B is in a rest state, and when the area B is vibrated, the area A is in a rest state. . Therefore, at the time of driving, half the area of the stator portion 100 is always idle. On the other hand, in the present embodiment, the entire area of the stator portion 100 is vibrated during driving to generate a high output.

FIG. 13A shows a schematic view of the ultrasonic motor of the embodiment developed in the circumferential direction.

The protrusion 32 of this embodiment is located between the antinode of the first standing wave shown in FIG. 13 (B) and the node on the right side thereof, and the second protrusion shown in FIG. 13 (C). It is formed so as to be located midway between the antinode of the standing wave and the node on its left side.

In this ultrasonic motor, when the A-phase AC voltage and the B-phase AC voltage are applied to both the A-phase polarization region and the B-phase polarization region of the piezoelectric element 10 in the same manner as in the second embodiment, the stator section is obtained. The first standing wave vibration shown in FIG. 13B is generated on the rotor contact surface 110 of 100. This standing wave vibration is a superposition of the vibration waveforms shown in FIGS. 11B and 11C.

At this time, elliptical vibration is generated on the end surface of the protrusion 32 in the direction indicated by the arrow in the figure, which causes the rotor 2 to rotate.
00 is driven to rotate rightward in the figure.

Further, an A-phase AC voltage is applied to the A-phase polarized region of the piezoelectric element 10, and a B-phase AC voltage and 1 are applied to the B-phase polarized region.
When the B′-phase AC voltages having a phase difference of 80 ° are applied, the second standing wave vibration shown in FIG. 13C is generated on the rotor contact surface 110.

This standing wave vibration is a superposition of the vibration waveform shown in FIG. 11 (B) and the vibration waveform shown by the broken line in FIG. 11 (C).

At this time, elliptical vibration is generated on the end surface of the protrusion 32 in the direction indicated by the arrow in the figure, which causes the rotor 2 to rotate.
00 is rotated leftward in the figure.

As described above, in this embodiment, the stator portion 1
00 vibrates and drives the rotor unit 200 to rotate, so that a larger output torque can be obtained from the rotor unit 200 as compared with the third embodiment.

The specific structure of the control circuit for controlling the operation of the ultrasonic motor is almost the same as that shown in FIG. In this case, the power supply circuits are in phase with each other.
One AC voltage (A phase, B phase) can be output at the same time, or two AC voltages of opposite phases, A phase and B'phase, can be output at the same time. This selection operation is indicated by the rotation direction input 86. Is configured.

Fifth Embodiment Next, a preferred fifth embodiment of the present invention will be described. Since the basic configuration of the ultrasonic motor of this embodiment is the same as that of the previous embodiment, only the characteristic part will be described here, and the other description will be omitted.

FIG. 14 shows an exploded perspective view of the stator portion 100 of the ultrasonic motor of the embodiment. The stator portion 100 of this embodiment includes two piezoelectric elements 10A and 10B.
And a vibrating elastic body 30, and these members are laminated and fixed using an adhesive.

The piezoelectric element 10A is divided into six equal parts every 60 °, and adjacent regions are formed so that their polarization directions are opposite to each other. Similarly, the piezoelectric element 20B is divided into six equal parts every 60 °, and is formed such that the polarization directions of the adjacent regions are opposite to each other. The respective piezoelectric elements 10A and 10B are three-dimensionally arranged so that the phases of the polarization regions deviate from each other by 30 °.

An AC voltage of A phase is applied to each polarization region of the piezoelectric element 10A, and the piezoelectric element 10A
A B-phase AC voltage can be applied to each polarization region of B.

FIG. 15A shows a diagram in which the ultrasonic motor of the embodiment is developed in its circumferential direction.

The protrusion 32 of this embodiment is located between the antinode of the first standing wave shown in FIG. 15B and the node on the right side thereof, and the second constant shown in FIG. 15C. It is formed so as to be located midway between the antinode of the standing wave and the node on its left side.

With the above configuration, the piezoelectric element 1
When the A-phase AC voltage is applied to each polarization region 12 of 0 A, the first standing wave vibration shown in FIG. 15B is generated on the rotor contact surface 110 of the stator part. At this time, the protrusion 32
Elliptical vibration occurs on the end face of the in the direction indicated by the arrow in the figure,
The rotor unit 200 is driven to rotate rightward in the figure.

On the contrary, when a B-phase AC voltage is applied to each polarization region of the piezoelectric element 10B, the rotor contact surface 1
In FIG. 10, the second standing wave vibration indicated by the solid line in FIG. As a result, on the end surface of the protrusion 32,
Elliptical vibration occurs in the direction indicated by the arrow in the figure, and the rotor portion 20
0 is driven to rotate leftward in the figure.

As described above, according to the present embodiment, the rotor section 200 can be driven in the forward and reverse directions by switching the applied AC voltage.

Sixth Embodiment Next, a sixth embodiment of the present invention will be described. The ultrasonic motor of the embodiment is different from the fifth embodiment only in the arrangement of the protrusions 32 formed on the rotor contact surface 110, and the other basic configuration is the same as that of the fifth embodiment. Here, only the characteristic part will be described, and the other description will be omitted.

In the fifth embodiment, when one piezoelectric element is vibrated, the other piezoelectric element is in a rest state, but in the present embodiment, the two piezoelectric elements 10A and 10B are driven simultaneously, It is characterized in that a large output torque is obtained.

FIG. 16A shows a diagram in which the ultrasonic motor of the embodiment is developed in the circumferential direction.

The protrusion 32 of this embodiment is located between the antinode of the first standing wave shown in FIG. 16 (B) and the node on the right side thereof, and the second constant shown in FIG. 16 (C). It is formed so as to be located midway between the antinode of the standing wave and the node on its left side.

With the above configuration, the piezoelectric element 1
When the A-phase and B-phase AC voltages are simultaneously applied to 0A and 10B, respectively, the rotor contact surface 110 of the stator 100 is
16B, the first standing wave vibration shown in FIG.
This standing wave vibration is a combination of the standing wave vibrations shown by the solid lines in FIGS.

At this time, elliptical vibration indicated by an arrow in the drawing is generated on the end surface of the protrusion 32, and the rotor portion 200 is driven to rotate rightward in the drawing.

Further, the piezoelectric element 10A and the piezoelectric element 10B
The A phase AC voltage and the B'phase AC voltage (B phase and 1
When a voltage having a phase difference of 80 degrees is applied, the stator unit 1
No. 2 on the rotor contact surface 110 of No. 00 shown in FIG.
The standing wave vibration of is generated. This standing wave vibration is shown in FIG.
The vibration shown in (B) and the vibration shown by the broken line in FIG. At this time, elliptical vibration is generated on the end surface of the protrusion 32, and the rotor unit 200 is rotationally driven leftward in the drawing.

As described above, according to the present embodiment, both the two piezoelectric elements 10A and 10B can be driven at the same time, and the rotor portion 200 can be rotationally driven. Therefore, compared with the ultrasonic motor of the fifth embodiment, A large output torque can be obtained.

Seventh Embodiment FIG. 17 shows a seventh preferred embodiment of the present invention.

In the ultrasonic motor of the embodiment, since the structure of the stator section 100 is the same as that of the first embodiment,
The detailed description is omitted here.

In the present embodiment, a plurality of slit portions 54 are formed on the stator contact surface of the rotor portion 200 at regular intervals along the rotation direction thereof.

With the above configuration, when the rotor portion 200 is driven in the normal direction by using the vibration motor of the embodiment, the A-phase polarized regions 12-1, 12-2,
...... Apply single-phase AC voltage to 12-5. This allows
As shown in FIG.
Ultrasonic vibration of the first standing wave as shown in (B) is generated. At this time, the protrusions 32 of the group located in the middle of 90 to 180 degrees of the first standing wave are A of the stator 100.
When the area is extended, the rotor section 200 acts so as to be pushed rightward in the drawing. When the protruding portion 32 comes to the position of the slit portion 54 of the rotor portion 200, the protruding portion 32 and the rotor portion 200 are brought into a non-contact state, and the rotor portion 20 is no longer in contact.
Since 0 cannot be pushed rightward in the figure, the rotation of the rotor unit 200 is temporarily stopped.

Next, when the area A of the stator portion 100 contracts, the protrusions 32 of the other group located in the middle of 270 to 360 degrees of the first standing wave push the rotor portion 200 to the right in the figure. It acts so as to take out, and rotationally drives the rotor unit 200. Then, when the protrusion 32 comes to the position of the slit portion 54, the protrusion 32 and the rotor unit 200 are brought into a non-contact state,
The rotation of the rotor unit 200 is temporarily stopped.

As described above, according to the ultrasonic motor of the embodiment, by utilizing the phenomenon that the protrusion 32 and the rotor portion 200 are not in contact with each other in the slit portion 54 and the rotor portion 200 cannot be pushed any more, The rotor unit 200 can be driven by stepping.

Although the ultrasonic motor of the first embodiment is taken as an example and the stepping drive is shown here, the rotors of the ultrasonic motors of the second to sixth embodiments are also shown. By similarly forming the slit portion 54 in the portion 200, the rotor portion 200 can be driven by stepping.

The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the present invention.

For example, in the above-mentioned embodiment, the case where the rotor part makes a circular motion has been described as an example, but the present invention is not limited to this, and the rotor part is a linear type which makes a one-dimensional motion such as a straight line other than a circular motion. It can also be applied to the ultrasonic motor.

[0102]

As described above, according to the present invention,
The standing wave generated on the rotor contact surface of the stator part is converted into an elliptical motion using the protrusions and the rotor part is driven to rotate. There is an effect that the ultrasonic motor can be obtained.

Further, according to the second aspect of the present invention, it is possible to obtain an ultrasonic motor capable of driving the rotor portion in the forward and reverse directions by generating standing waves having different phases on the rotor contact surface.

Furthermore, according to the third aspect of the present invention, by forming a plurality of slit portions at predetermined intervals on the stator contact surface of the rotor portion, it is possible to obtain an ultrasonic motor capable of stepping driving the rotor portion.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a first preferred embodiment of an ultrasonic motor according to the present invention.

FIG. 2 is a perspective view showing the appearance of the ultrasonic motor according to the first embodiment with a part thereof cut away.

FIG. 3 is an exploded perspective view of a stator portion of the ultrasonic motor shown in FIG.

FIG. 4 is an explanatory diagram of a surface of a piezoelectric element used in this example.

FIG. 5 is an explanatory diagram of the back surface of the piezoelectric element used in this example.

FIG. 6 is an explanatory diagram of a control circuit of the ultrasonic motor according to the embodiment.

FIG. 7 is an explanatory diagram of a modified example of the first embodiment.

FIG. 8 is a schematic explanatory diagram of a second embodiment.

FIG. 9 is an explanatory diagram of a piezoelectric element used in the third embodiment.

10 is a schematic explanatory diagram of a voltage application region of the piezoelectric element shown in FIG.

FIG. 11 is a schematic explanatory diagram of an ultrasonic motor according to a third embodiment.

FIG. 12 is an explanatory diagram of a modification of the third embodiment.

FIG. 13 is a schematic explanatory diagram of an ultrasonic motor according to a fourth embodiment.

FIG. 14 is an exploded perspective view showing a stator portion used in the ultrasonic motor of the fifth embodiment.

FIG. 15 is a schematic explanatory diagram of an ultrasonic motor according to a fifth embodiment.

FIG. 16 is a schematic explanatory diagram of an ultrasonic motor according to a sixth embodiment.

FIG. 17 is a schematic explanatory diagram of an ultrasonic motor according to a seventh embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Piezoelectric element 30 Vibration elastic body 32 Projection part 54 Slit part 100 Stator part 110 Rotor contact surface 200 Rotor part

Claims (3)

[Claims] 1. An ultrasonic motor comprising: a flat stator portion; and a rotor portion which is pressed against a rotor contact surface of the stator portion and driven in a predetermined direction, wherein the stator portion has a rotor contact on a front surface side. A vibrating elastic body having a surface formed thereon, a piezoelectric element provided on the back surface side of the vibrating elastic body, and having a plurality of voltage application regions formed along the moving direction of the rotor section; A plurality of protrusions formed along the direction, and by applying an AC voltage to the voltage application region of the piezoelectric element, a standing wave is generated on the rotor contact surface, and an antinode of the standing wave is generated. An elliptical vibration is generated in the protrusion by providing the protrusion between the node and the node, and the rotor portion in contact with the protrusion is moved. 2. An ultrasonic motor comprising: a flat stator portion; and a rotor portion that is pressed against a rotor contact surface of the stator portion and is driven in a predetermined direction, wherein the stator portion has rotor contact on a front surface side. A vibrating elastic body having a surface formed thereon, a piezoelectric element provided on the back surface side of the vibrating elastic body, and having a plurality of voltage application regions formed along the moving direction of the rotor section; A plurality of protrusions formed along the direction, and a first standing wave and a second standing wave having different phases on the rotor contact surface by switching control of an alternating voltage applied to the voltage application region of the piezoelectric element. Is formed so as to selectively generate a standing wave of the second standing wave, and the plurality of protrusions are located between the antinode of the first standing wave and the node on one side. Located between the belly and the node on the other side Vibration motor is so that formed, the AC voltage to control switching the applied, by selecting the standing wave generated, characterized by switching the moving direction of the rotor portion in contact with the protrusion. 3. The stator according to claim 1, wherein slit portions are provided on the stator contact surface side of the rotor portion at predetermined intervals, and the protrusion portion and the rotor portion are in contact with each other by the slit portion. An ultrasonic motor characterized by driving the rotor section by stepping when it is eliminated.