JPH1141955A - Ultrasonic-wave motor and piezoelectric vibrator using motor thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic-wave motor characterized by light weight, small thickness, stable operation, high efficiency and a piezoelectric vibrator which uses the motor thereof. SOLUTION: A disc-shaped vibrator 3, which is formed by overlapping and connecting a disc-shaped elastic body 1 to a disc-shaped piezoelectric body 2 having drive electrodes at both sides, a moving body 4, which is arranged in contact with the elastic body 1 through compression, and a vibrating-body fixing tool 5, which fixes the vibrating body 3, are provided. A moving body 4 is rotated by exciting the standing waves of the deflecting vibration in a secondary or higher order in the radial direction to the vibrating body 3 and tertiary or higher order in the circumferential direction by the AC drive voltage applied to a drive electrode. The position, where the vibrating-body fixture 5 fixes the vibrating body 3, is the position, where the deflecting vibration other than the standing wave to be excited is smaller than in the case when the vibrating body 3 is fixed to only the central part of the body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic wave generating a driving force by exciting a standing wave of an elastic wave to a vibrating body comprising a piezoelectric body and an elastic body using a piezoelectric body such as a piezoelectric ceramic. The present invention relates to a motor and a piezoelectric vibrator using the same.

[0002]

2. Description of the Related Art In recent years, attention has been focused on a ringing vibrator instead of a ringing sound of a portable communication device such as a mobile phone, a PHS, and a pager. Hereinafter, the prior art of a vibrator will be described with reference to the drawings, focusing on a motor as a driving source thereof.

[0003] Conventionally, electromagnetic motors are often used as paging piebrators. FIG. 17 is a perspective view of a conventional electromagnetic vibrator using an electromagnetic motor. 101
Is a cylindrical electromagnetic motor, 102 is a cylindrical electromagnetic motor 101
And 103, an eccentric weight attached to the rotating shaft 102. When a DC voltage is applied to the cylindrical electromagnetic motor 101, the cylindrical electromagnetic motor 101 rotates around the rotation shaft 102. Since the rotating shaft 102 is provided with the eccentric weight 103, the cylindrical electromagnetic motor 101 vibrates according to the rotation speed. Mobile phones, PH
It can be attached to S, pager, etc. to notify the call by vibration instead of ringing sound.

FIG. 18 is a perspective view of another conventional electromagnetic vibrator. 104 is a flat electromagnetic motor, 105 is a rotating shaft of the flat electromagnetic motor 104, and 106 is an eccentric weight attached to the rotating shaft 105. Flat electromagnetic motor 10
When a DC voltage is applied to the motor 4, the flat electromagnetic motor 104 rotates about the rotation shaft 105. Since the eccentric weight 106 is attached to the rotating shaft 105, the flat electromagnetic motor 1
04 vibrates according to the rotation speed. This electromagnetic vibrator can be attached to a mobile phone, a PHS, a pager, or the like so that a call can be notified by vibration instead of a ring tone.

As a rotary actuator, not only an electromagnetic motor but also an ultrasonic motor can be considered as a vibrator. Ultrasonic motors include a traveling wave type and a standing wave type, but the standing wave type is not used as a vibrator because of the problems described below. Therefore, only the traveling wave type will be described here. FIG. 19 is a cutaway perspective view of a ring-shaped traveling-wave type ultrasonic motor, in which a ring-shaped elastic body 111 having a large number of protrusions formed on one of the ring faces is provided with a drive-use elastic body 111. Ring-shaped piezoelectric ceramic 11 as piezoelectric body
2 by means of an adhesive or the like to form a ring-shaped vibrating body 113.
Is composed. Reference numeral 114 denotes a friction material made of a wear-resistant material;
Reference numeral 5 denotes an elastic body, which is bonded to each other to form a moving body (rotating body) 116. The moving body 116 is the friction material 11
Although not shown here, the pressure sensor 4 is placed in pressure contact with the vibrating body 113 via a pressure means such as a spring.

FIG. 20 is a structural view of a drive electrode formed on the piezoelectric ceramic 112 of FIG.
Two sets of drive electrodes A and B which are shifted in position by four wavelengths are formed. The drive electrodes A and B are each composed of a small electrode group having a length corresponding to a half wavelength. The electrodes C and D have a length corresponding to ／ wavelength and １ ／ wavelength, respectively, and are formed to create a positional shift corresponding to １ ／ wavelength between the drive electrodes A and B. Therefore, the driving electrodes are only A and B, and the electrodes C and D do not need to form electrodes.

When two AC voltages having phases different from each other by 90 degrees are applied to the drive electrodes A and B (for example, a sine wave and a cosine wave), a traveling wave of bending vibration as shown in FIG. You. Here, FIG. 21A shows a vibration mode of bending vibration, and FIG. 21B shows a radial displacement distribution. In the ring-type ultrasonic motor, a traveling wave of bending vibration of first order in the radial direction and third order or more in the circumferential direction is excited by the vibrating body 113. The transverse component of the wave front of this traveling wave is the vibrating body 1
The moving body 116 is rotated by friction driven by the expanded lateral displacement component and is rotated. If an eccentric weight is installed on the moving body 116, it operates as a vibrator.

[0008]

It is important to reduce the weight and thickness of portable communication devices such as mobile phones, PHSs, and pagers. A ringing vibrator is often used together with the ringing sound. However, in a conventional vibrator using a cylindrical electromagnetic motor as a drive source, its thickness is determined by the diameter of the cylindrical electromagnetic motor. Therefore, in order to reduce the thickness of the vibrator, it is necessary to reduce the diameter of the cylindrical electromagnetic motor. However, since the diameter of the cylindrical electromagnetic motor cannot be so small to realize the output torque required for rotating the eccentric weight, there is a problem that it is difficult to reduce the thickness of the cylindrical electromagnetic motor. Further, since the output per unit weight of the electromagnetic motor is small, there is also a problem that the weight increases in order to obtain a required output.

[0009] In the case of a vibrator using a flat type electromagnetic motor in order to realize a thin type, the thickness of the flat type electromagnetic motor is required to realize an output torque necessary for rotating an eccentric weight. Has a problem that there is a limit to the reduction in thickness. Further, since the output per unit weight of the electromagnetic motor is small, there is also a problem that the weight increases in order to obtain a required output.

An ultrasonic motor may be used instead of an electromagnetic motor in order to achieve a reduction in weight and thickness. However, a conventional traveling wave type ultrasonic motor has a vibrating body as shown in FIG. A large number of protrusions are formed on the elastic body. Therefore, when the size of the ultrasonic motor is reduced, the size of the projection is reduced to make machining difficult, and when the projection is thinner, the bending rigidity of the projection is reduced, and the projection is moved by a lateral displacement component due to a traveling wave. There is a problem that the body cannot be driven sufficiently. Further, the conventional ultrasonic motor uses a traveling wave as a driving source, so that the structure of the driving electrode becomes complicated, and the driving circuit becomes complicated because two driving signals having a phase shift of 90 degrees are required. Has the problem of becoming

In contrast to the traveling wave type ultrasonic motor, the standing wave type ultrasonic motor used as the ultrasonic motor of the present invention has a relatively simple drive electrode and can be easily machined, but has a disadvantage in that it has a rotational motion. Since a vibration mode other than the required frequency is excited, there is a problem that it is unstable and inefficient.

The present invention has been made in consideration of the above-mentioned problems of a conventional motor and a vibrator using the motor, and has been made in consideration of the above problems. It is an object of the present invention to provide a piezoelectric vibrator using the same.

[0013]

According to a first aspect of the present invention, there is provided a disk-shaped piezoelectric body formed by superposing a disk-shaped elastic body on a disk-shaped piezoelectric body having drive electrodes on both surfaces thereof and joining them together. A vibrating body, a moving body disposed in pressure contact with the elastic body, and a fixture for fixing the vibrating body, wherein the moving body has an AC drive voltage applied to the drive electrode, The vibrating body is rotated by exciting a standing wave of bending vibration of second order or more in the radial direction and third order or more in the circumferential direction to rotate, and the position where the fixing member fixes the vibrating body is to be excited. The ultrasonic motor according to claim 1, wherein a bending vibration other than the standing wave is smaller than a position where the vibrating body is fixed only at a center portion thereof.

According to a second aspect of the present invention, the vibrating body has a small hole in the center portion, and the fixing tool is connected to the vibrating body via the small hole and the bending circle of the bending vibration. 2. The ultrasonic motor according to claim 1, wherein the ultrasonic motor is fixed.

According to a third aspect of the present invention, the vibrating body has a small hole in the center portion, and the fixing tool includes the small hole and a part of at least one node diameter portion of the bending vibration. Through,
The ultrasonic motor according to claim 1, wherein the vibrating body is fixed.

According to a fourth aspect of the present invention, the vibrating body has a small hole in the central portion, and the fixing member is formed of the small hole, the bending circle portion of the bending vibration and at least one bending diameter portion. The ultrasonic motor according to claim 1, wherein the vibrating body is fixed via a part thereof.

According to a fifth aspect of the present invention, there is provided the ultrasonic motor according to any one of the first to fourth aspects, wherein the piezoelectric body is disposed within a nodal circle of the bending vibration.

According to a sixth aspect of the present invention, the piezoelectric body is disposed in a region surrounded by a boundary where the sign of the charge induced in the piezoelectric body by the bending vibration is inverted. An ultrasonic motor according to any one of claims 1 to 4.

According to a seventh aspect of the present invention, there is provided the ultrasonic motor according to any one of the first to fourth aspects, wherein the piezoelectric body is arranged substantially over the entire area of one surface of the elastic body. .

According to an eighth aspect of the present invention, there is provided the ultrasonic motor according to any one of the fifth to seventh aspects, wherein the drive electrode is disposed within a nodal circle of the bending vibration.

According to a ninth aspect of the present invention, the drive electrode is disposed in a region surrounded by a boundary where the sign of the charge induced in the piezoelectric body by the bending vibration is inverted. An ultrasonic motor according to claim 6.

According to a tenth aspect of the present invention, among the driving electrodes, the first driving electrode is disposed in a region surrounded by a boundary where the sign of the charge induced in the piezoelectric body by the bending vibration is inverted. The ultrasonic motor according to claim 7, wherein the second drive electrode is arranged at an outer peripheral portion of the region.

According to a preferred embodiment of the present invention, among the driving electrodes, a first driving electrode is disposed within a node of the bending vibration, and a second driving electrode is disposed at an outer peripheral portion of the node. The ultrasonic motor according to claim 7, wherein

12. The method according to claim 10, wherein the first drive electrode and the second drive electrode are used when the piezoelectric body is polarized, and only the first drive electrode is used when the piezoelectric body is driven. Or an ultrasonic motor according to item 11.

According to a thirteenth aspect of the present invention, the driving electrode comprises:
The ultrasonic motor according to claim 1, wherein the ultrasonic motor is not in direct contact with the fixing tool.

According to a fourteenth aspect of the present invention, there is provided a piezoelectric vibrator comprising the ultrasonic motor according to any one of the first to thirteenth aspects and an eccentric weight disposed on the moving body. .

[0027]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
It is sectional drawing of the ultrasonic motor and the piezoelectric vibrator using the same in Embodiment. In FIG. 1, reference numeral 1 denotes a circular elastic body made of a material such as metal or ceramic which easily stores elastic vibration energy, and reference numeral 2 denotes a circular piezoelectric body made of a material such as single crystal or ceramic. The body 2 is bonded to each other with an adhesive such as an epoxy resin to form a circular vibrating body 3. The outer diameter of the piezoelectric body 2 is equal to the outer diameter of the elastic body 1. Vibrator 3
Has a small hole 8 penetrating the elastic body 1 and the piezoelectric body 2 at the center thereof, and as will be described later, the vibrating body The position is fixed circumferentially by the fixture 5. Reference numeral 4 denotes a moving body made of metal, plastic, or the like, which is installed in pressure contact with an output take-out projection 7 formed on the vibrating body 3 as shown in FIG. Reference numeral 10 denotes a rotating shaft that penetrates the small hole 8 and the vibrating body fixture 5 and contacts the moving body 4. Although not necessary in principle of operation, a wear-resistant material may be formed on the surface of the moving body 4 in contact with the vibrating body 3 to improve reliability. May be configured. As described above, the ultrasonic motor according to the present embodiment is configured, and by installing the eccentric weight 90 on a part of the moving body 4, the piezoelectric vibrator according to the present embodiment is obtained.

FIG. 2 shows an example of driving electrodes formed on the piezoelectric body 2 constituting the vibrating body 3. Although not shown here, the back surface of the surface shown in FIG. The small drive electrodes 9 are small electrodes corresponding to a half wavelength of the bending vibration in the circumferential direction, and the small drive electrodes 9 adjacent to each other are polarized in the direction opposite to the thickness direction. The surface of the piezoelectric body 2 shown in FIG. When the elastic body 1 has no conductivity, it is necessary to short-circuit the small drive electrodes 9 to each other in advance by means such as sputtering or vapor deposition.

When the surface of the small drive electrode 9 of the piezoelectric body 2 shown in FIG. 2 is used as a common electrode, an AC voltage near the resonance frequency of the vibrator 3 is applied to the solid electrode on the back surface of the surface of the piezoelectric body 2 shown in FIG. Then, bending vibration having the displacement distribution 6 shown in FIG. Here, radial second order (radial primary vibration has no node circle, secondary vibration has one node circle) / circumferential third order (three waves exist in circumferential direction) Is excited. However, in general, lower-order flexural vibrations are easier to excite, and in addition to radial secondary / peripheral tertiary flexural vibrations, particularly radial primary / peripheral tertiary flexural vibrations and other vibrations are also excited. Resulting in.

FIG. 3 is an operation principle diagram of the ultrasonic motor in the present embodiment, and is an operation model diagram in which the ultrasonic motor of FIG. 1 is linearized along the circumferential direction. When an AC voltage is applied to the piezoelectric body 2 constituting the vibrating body 3, a standing wave of bending vibration as shown in FIG. 3 is excited. The flexural vibration shown in the figure simultaneously represents a vibration displacement 180 degrees out of phase with respect to time. Each of the protrusions 7a, b, c,...
(3) drives the moving body 4 in the direction of the arrow by displacing both vertically and horizontally by bending vibration as shown in FIG.
That is, the operation in which the protrusions 7a and 7c drive the moving body 4 at a certain moment and the movement of the moving body 4 by the 7b at the next moment are repeated. When the vibrating body 3 is driven by such an operation principle, the moving body 4 starts rotating. Since the eccentric weight 90 is provided on the moving body 4, the vibrator operates by vibrating violently.

According to the principle of operation, when different vibrations such as radial primary / circular tertiary as well as radial primary / circular tertiary are excited in the vibrating body 3, the projection 7 efficiently moves. 4 cannot be driven, and the efficiency of the ultrasonic motor and the piezoelectric vibrator is significantly reduced. Accordingly, as shown in FIG. 1, the vibrating body 3 is vibrated through both the vicinity of the small hole 8 of the vibrating body and the position of the nodal circle of the vibration in order to suppress the vibration in the primary direction in the radial direction / tertiary direction in the circumferential direction. The position is fixed by the body fixture 5. This makes it difficult to excite other vibration modes, so that only the radial secondary vibration / circumferential tertiary flexural vibration, which is the driving force, can be efficiently excited. In particular, the vibration state can be stably maintained even when the external load changes.

That is, in the present embodiment, the radial primary /
In order to suppress low-order vibration modes such as the third order in the circumferential direction and other vibration modes, the position of the vibration body is fixed through both the center of the vibration body and the position of the nodal circle of the vibration, so that the low-order vibration mode is reduced. Vibration mode and other vibration modes are difficult to excite,
Only the radial secondary vibration / circumferential tertiary bending vibration, which is the driving force, can be efficiently excited. In particular, the vibration state can be stably maintained even when the load changes. As a result, it is possible to provide an ultrasonic motor capable of realizing both high efficiency and high stability, and a piezoelectric vibrator using the same.

Here, the radial secondary / circumferential tertiary bending motion has been briefly described. However, even in the case of radial secondary / circumferential tertiary or higher, the position of the nodal circle changes. Accordingly, exactly the same effect can be obtained by changing the fixed position of the vibrator.

(Second Embodiment) FIG. 4 shows a second embodiment of the present invention.
It is sectional drawing of the ultrasonic motor and the piezoelectric vibrator using the same in Embodiment. This embodiment is different from the first embodiment in the position where the vibrating body fixture fixes the vibrating body. In FIG. 1, reference numeral 11 denotes a circular elastic body made of a material such as metal or ceramic which easily stores elastic vibration energy, and reference numeral 12 denotes a circular piezoelectric body made of a material such as single crystal or ceramic. The body 12 is adhered to each other with an adhesive such as an epoxy resin to form a circular vibrating body 13. Piezoelectric body 1
The outer diameter of 2 is equal to the outer diameter of the elastic body 11. The vibrating body 13 has a small hole 18 at the center thereof, which penetrates the elastic body 11 and the piezoelectric body 12.
It is circumferentially fixed by the vibrator fixture 15 through both the vicinity of 8 and the position of at least one node diameter. Reference numeral 14 denotes a moving body made of metal, plastic, or the like. As shown in the drawing, the moving body 14 is placed in pressure contact with an output take-out projection 17 formed on the vibrating body 13. Reference numeral 20 denotes a rotating shaft that penetrates the small hole 18 and the vibrating body fixture 15 and contacts the moving body 14. Although not necessary in terms of the operation principle, a wear-resistant material may be formed on the surface of the moving body 14 in contact with the vibrating body 13 to improve reliability. May be configured. As described above, the ultrasonic motor according to the present embodiment is configured, and by mounting the eccentric weight 90 on a part of the moving body 14, the piezoelectric vibrator according to the present embodiment is obtained.

The driving electrodes of the piezoelectric body 12 constituting the vibrating body 13 are the same as those in the first embodiment, and therefore the description is omitted. When an AC voltage having a frequency near the resonance frequency of the vibrating body 13 is applied to the piezoelectric body 12, bending vibration having a displacement distribution 16 shown in FIG. In this case, radial secondary vibration / circumferential tertiary bending vibration is excited. However, the vibrating body 13 generally excites other various kinds of vibrations in addition to the radial secondary / circumferential tertiary bending vibration. In addition, the radial vibration secondary / circumferential tertiary flexural vibration also changes the position of the node diameter depending on the load condition and the fixing condition.

The principle of operation of the present embodiment is the same as that of the first embodiment, and therefore detailed description is omitted. However, similar to the first embodiment, when the vibrating body 13 is driven,
Starts spinning. The eccentric weight 90 is attached to the moving body 14.
Vibrator vibrates violently because it is installed. According to the principle of operation, another vibration is excited together with the radial secondary and the circumferential tertiary, and when the node diameter position changes,
The projection 17 cannot drive the moving body 14 efficiently and stably, and the efficiency and stability of the ultrasonic motor and the piezoelectric vibrator are significantly reduced. Therefore, in order to suppress another vibration and to fix the position of the node diameter, as shown in FIG. 4, the vibration occurs through both the vicinity of the small hole 18 of the vibrating body 13 and the position of at least one node diameter. The body 13 is fixed. As a result, it becomes difficult to excite other vibration modes, and the position of the nodal diameter cannot be changed.
Only the third-order / circumferential third-order bending vibration can be efficiently and stably excited. In addition, since the vibration state can be kept stable even when the load changes, it is possible to provide an ultrasonic motor and a piezoelectric vibrator using the same, which can realize both high efficiency and high stability.

That is, in the present embodiment, in order to suppress another vibration mode and to fix the position of the nodal diameter, the vibrating body is circumferentially connected to the vibrating body via both the nodal diameter positions. By fixing, it becomes difficult to excite other vibration modes and the position of the nodal diameter cannot be changed. Therefore, only the radial secondary / circumferential tertiary flexural vibration, which is the driving force, can be efficiently excited. In addition, since the vibration state can be kept stable even when the load changes, it is possible to provide an ultrasonic motor and a piezoelectric vibrator using the same, which can realize both high efficiency and high stability.

Here, a brief description has been given of the radial secondary / circumferential tertiary bending motion. However, even in the case of radial secondary / circumferential tertiary or higher, the position of the node diameter changes. Accordingly, exactly the same effect can be obtained by changing the fixed position of the vibrator.

(Third Embodiment) FIG. 5 shows a third embodiment of the present invention.
It is sectional drawing of the ultrasonic motor and the piezoelectric vibrator using the same in Embodiment. This embodiment is different from the first embodiment in the position where the vibrating body fixture fixes the vibrating body, as in the second embodiment. In the figure, reference numeral 21 denotes a circular elastic body made of a material that easily stores elastic vibration energy such as metal or ceramic;
Reference numeral 22 denotes a circular piezoelectric body made of a material such as single crystal or ceramic. The elastic body 21 and the piezoelectric body 22 are bonded to each other with an adhesive such as epoxy resin to form a circular vibrating body 2.
3. The outer diameter of the piezoelectric body 22 is equal to the outer diameter of the elastic body 21. The vibrating body 23 has a small hole 28 penetrating the elastic body 21 and the piezoelectric body 22 at the center thereof,
As will be described later, the vicinity of the small hole 28 is fixed circumferentially, and the position is fixed circumferentially by the vibrating body fixing tool 25 via both the node circle and the position of at least one node diameter. . Reference numeral 24 denotes a moving body made of metal, plastic, or the like, which is placed in pressure contact with an output take-out projection 27 formed on the vibrating body 23 as shown in FIG. Reference numeral 30 denotes a rotating shaft that penetrates the small hole 28 and the vibrating body fixture 25 and contacts the moving body 24. Although not necessary in principle of operation, the moving body 2
The surface in contact with the vibrator 23 of 4 may be made of a wear-resistant material, or the moving body 24 itself may be made of a wear-resistant material. As described above, the ultrasonic motor according to the present embodiment is configured, and by installing the eccentric weight 90 on a part of the moving body 24, it becomes the piezoelectric vibrator according to the present embodiment.

The driving electrodes of the piezoelectric body 22 constituting the vibrating body 23 are the same as those in the first embodiment, and therefore the description is omitted. When an AC voltage having a frequency near the resonance frequency of the vibrating body 23 is applied to the piezoelectric body 22, a bending vibration having a displacement distribution 26 shown in FIG. In this case, radial secondary vibration / circumferential tertiary bending vibration is excited. However, the vibrating body 23 generally excites other various kinds of vibrations in addition to the radial secondary / circumferential tertiary flexural vibration. Further, the node diameter and the position of the node circle of the radial vibration secondary / circumferential tertiary flexural vibration also change depending on the load condition and the like.

Since the principle of operation of this embodiment is the same as that of the first embodiment, detailed description is omitted. However, as in the first embodiment, when the vibrating body 23 is driven,
Starts spinning. The eccentric weight 90 is attached to the moving body 24.
Vibrator vibrates violently because it is installed. Due to the principle of operation, another vibration is excited together with the radial secondary / circumferential tertiary, and if the nodal diameter or the nodal circle position of the radial secondary / circumferential tertiary flexural vibration changes due to load conditions, etc. The body 27 cannot drive the moving body 24 efficiently and stably, and the efficiency and stability of the ultrasonic motor and the piezoelectric vibrator are significantly reduced. Therefore, in order to suppress another vibration, as shown in FIG. 5, the vicinity of the small hole 28 of the vibrating body 23 is fixed circumferentially, and the vibrating body is connected through both the nodal circle and the position of at least one nodal diameter. 23 is fixed. As a result, it becomes difficult to excite other vibration modes, and the node diameter and the position of the node circle of the bending vibration hardly change depending on the load condition, and the vibration state can be kept stable even if the load changes. Only the radial secondary vibration / circumferential tertiary bending vibration, which is the driving force, can be efficiently and stably excited. Further, it is possible to provide an ultrasonic motor that can realize both high efficiency and high stability, and a piezoelectric vibrator using the same.

That is, in this embodiment, in order to suppress another vibration mode, the center of the vibrating body is fixed circumferentially, and the vibrating body is fixed via both the nodal circle and the nodal diameter position. I do. As a result, it becomes difficult to excite other vibration modes, and the node diameter and the position of the node circle of the bending vibration hardly change depending on the load condition, and the vibration state can be kept stable even if the load changes. , Radial direction 2 which is the driving force
Only the third-order / circumferential third-order bending vibration can be efficiently and stably excited. Further, it is possible to provide an ultrasonic motor that can realize both high efficiency and high stability, and a piezoelectric vibrator using the same.

Here, the bending motion in the radial secondary / circumferential tertiary order has been briefly described. However, even in the case of radial secondary / circumferential tertiary or higher, the positions of the nodal circle and the nodal diameter are also considered. The same effect can be obtained by changing the fixed position of the vibrating body as the value changes.

(Fourth Embodiment) FIG. 6 shows a fourth embodiment of the present invention.
It is sectional drawing of the ultrasonic motor and the piezoelectric vibrator using the same in Embodiment. This embodiment differs from the first embodiment in the arrangement of the piezoelectric bodies and the drive electrodes. In the figure, reference numeral 31 denotes a circular elastic body made of a material that easily stores elastic vibration energy such as metal or ceramic, and 32 denotes a circular piezoelectric body made of a material such as single crystal or ceramic. Body 32
Are bonded to each other with an adhesive such as epoxy resin to form a circular vibrating body 33. As described later, the outer diameter of the piezoelectric body 32 is configured to be within the area of the nodal circle position of the flexural vibration. Further, the piezoelectric body 32 is arranged so as to avoid direct fixation with the vibrating body fixture 35 in order to suppress the vibration inhibition as much as possible. The vibrating body 33 is
At the center thereof, a small hole 38 penetrating the elastic body 31 and the piezoelectric body 32 is provided.
The position is fixed by the vibrating body fixing tool 35 through both the vicinity and the position of the node of vibration. The elastic body 31 is provided with a projection 37 for taking out the output. Reference numeral 34 denotes a moving body made of a material such as metal or plastic, which is installed in pressure contact with a projection 37 formed on the vibrating body 33 as shown in FIG. 40 is a small hole 38
And a rotating shaft that penetrates the vibrating body fixture 35 and contacts the moving body 34. Although not necessary in principle of operation, a wear-resistant material may be formed on the surface of the moving body 34 in contact with the vibrating body 33 in order to improve reliability. May be configured. As described above, the ultrasonic motor according to the present embodiment is configured, and by installing the eccentric weight 90 on a part of the moving body 34, the piezoelectric vibrator according to the present embodiment is obtained.

FIG. 7A shows a radial secondary / circumferential tertiary or higher (in this case, the radial direction 2) which excites the vibrating body 33 shown in FIG.
Displacement distribution 36 of bending vibration of the next / circumferential tertiary bending)
FIG. 7B shows a distribution of charges induced in the piezoelectric body 32 by bending vibration. According to FIG. 7, the sign of the induced charge due to the vibration is inverted slightly outside the nodal circle where the vibration amplitude becomes zero. In order to efficiently excite a desired vibration mode, the drive electrode formed on the piezoelectric body 32 may have a total charge induced by vibration as large as possible. Therefore, the drive electrode in the present embodiment is formed in a region where the sign of the induced charge is the same and as large as possible.

FIG. 8 shows an example of driving electrodes formed on the piezoelectric body 32 constituting the vibrating body 33. The back surface of the piezoelectric body surface shown in FIG. The driving electrode is composed of a plurality of small driving electrodes 39, and the small driving electrode 39 is a small electrode corresponding to a half wavelength of the bending vibration in the circumferential direction. The small drive electrodes adjacent to each other are polarized in the direction opposite to the thickness direction. The piezoelectric body 32 is bonded to the elastic body 31 so that the surface shown in FIG. Therefore, when the elastic body 31 has no conductivity, it is necessary to short-circuit the small drive electrodes 39 with each other by means such as sputtering or vapor deposition.

The vibrating body 33 and the small driving electrode group 39 connected to the vibrating body 33 are used as common electrodes for the solid electrodes of the piezoelectric body 32,
When an AC voltage having a frequency near the resonance frequency of the vibrating body 33 is applied, the displacement distribution 3 shown in FIGS.
6 is excited. In this example, radial vibration secondary vibration (primary has no knot circle, secondary has one knot circle) / circumferential tertiary (three waves exist in circumferential direction) is excited. I have.

The principle of operation of this embodiment is the same as that of the first embodiment, and a detailed description is omitted. The drive electrode (small drive electrode group 39) shown in FIG. 8 is formed within the area of the nodal circle position of the flexural vibration shown in FIG. Then, in order to increase the amount of generated charges as much as possible, the area of the drive electrode in the region is made as large as possible. That is, FIG.
(A) is used for fixing the position of the vibrating body 33, and the piezoelectric body 32 is arranged in the area of the radius of the nodal circle. As shown in FIG. A drive electrode including the electrode 39 is formed. This makes it possible to minimize the vibration inhibition of the vibrating body 33 and at the same time increase the total charge amount.

According to the present embodiment, radial secondary vibration / circumferential tertiary bending vibration, which is a driving force, can be efficiently excited.
Further, it is possible to provide a piezoelectric vibrator that achieves both high efficiency and high stability.

That is, in the present embodiment, the position of the node is used for fixing the position of the vibrating body, the size of the piezoelectric body is set in the area of the node of the vibration, and a plurality of small drive electrodes are provided on the entire piezoelectric body. Is formed. Since the position of the nodal circle and the position where the sign of the induced charge is inverted are close to each other, it is possible to minimize the vibration inhibition of the vibrator and to increase the total charge amount. According to the present embodiment, the radial secondary /
Since the third-order flexural vibration in the circumferential direction can be efficiently excited, it is possible to provide an ultrasonic motor realizing both high efficiency and high stability and a piezoelectric vibrator using the same.

Here, the radial secondary / circumferential tertiary bending motion has been described briefly, but the radial secondary /
In the case of the third order or more in the circumferential direction, the same effect can be obtained by changing the size of the piezoelectric body as the position of the node circle changes.

In this embodiment, the piezoelectric body 3
2 and the drive electrode 39 are arranged in the area of the radius of the nodal circle, but the piezoelectric body 32 is arranged in the area where the sign of the charge distribution shown in FIG. It may be arranged in a region with a nodal circle radius or in a region where the sign of the charge distribution shown in FIG. 7B is inverted.

(Fifth Embodiment) FIG. 9 shows a fifth embodiment of the present invention.
It is sectional drawing of the ultrasonic motor and the piezoelectric vibrator using the same in Embodiment. This embodiment is different from the first embodiment in the arrangement of the drive electrodes.
In the figure, reference numeral 41 denotes a circular elastic body made of a material that easily stores elastic vibration energy such as metal or ceramic, and reference numeral 42 denotes a circular piezoelectric body made of a material such as single crystal or ceramic. The body 42 is bonded to each other with an adhesive such as an epoxy resin to form a circular vibrating body 43. As described later, the outer diameter of the piezoelectric body 42 is equal to the outer diameter of the elastic body 41. Vibrator 43
Has a small hole 48 penetrating through the elastic body 41 and the piezoelectric body 42 at the center thereof. The position is fixed through both positions. Also, the elastic body 41
Is provided with a projection 47 for taking out output. 4
Reference numeral 4 denotes a moving body made of a material such as metal or plastic, which is installed in pressure contact with a projection 47 formed on the vibrating body 43 as shown in FIG. Reference numeral 50 denotes a rotating shaft that penetrates the small hole 48 and the vibrating body fixture 45 and contacts the moving body 44. Although not necessary in principle of operation, the vibrating body 43 of the moving body 44 is used to improve reliability.
May be made of a wear-resistant material, or the moving body 44 itself may be made of a wear-resistant material. As described above, the ultrasonic motor according to the present embodiment is configured, and by installing the eccentric weight 90 on a part of the moving body 44, the piezoelectric vibrator according to the present embodiment is obtained.

The radial secondary / circumferential third or higher excited in the vibrating body 43 shown in FIG. 9 (here, radial secondary / circular third
The displacement distribution 36 of the bending vibration (the next bending vibration) and the distribution of charges induced in the piezoelectric body 42 by the bending vibration are the same as the distribution shown in FIG. According to FIG. 7, the sign of the induced charge due to the vibration is reversed slightly outside the node circle where the bending vibration amplitude becomes zero. In order to efficiently excite a desired vibration mode, the drive electrode formed on the piezoelectric body 42 may have a large total charge induced by vibration. Therefore, the drive electrode is formed in a region where the sign of the induced charge is the same and as large as possible. However, in the present embodiment, the position of the vibrating body 43 is fixed via the nodal section of the flexural vibration that is excited to minimize the vibration inhibition. Since the position where the sign of the induced charge is reversed is located outside the nodal circle portion, if the drive electrode portion is formed up to the position where the sign of the induced charge is reversed, the position of the vibrating body 43 is fixed from above the drive electrode. Is performed by the vibrating body fixing 45, and the operation of the ultrasonic motor / piezoelectric vibrator deteriorates the drive electrode. Also,
The resonance characteristic representing the characteristic of the vibrating body 43 as a vibrator is determined by the thickness of the base of the vibrating body 43 which is the sum of the elastic body 41 and the piezoelectric body 42. Therefore, in order to improve the characteristics of the vibrating body 43, it is preferable to make the thickness of the vibrating body 43 as constant as possible.

FIG. 10 shows an example of drive electrodes formed on the piezoelectric body 42 constituting the vibrating body 43. In order to make the thickness of the vibrating body 43 constant, the outer shape of the piezoelectric body 42 is made equal to the outer shape of the elastic body 41. The back surface of the piezoelectric body surface shown in the figure is a circular electrode, and its outer shape is formed to be substantially equal to the nodal circle diameter of the flexural vibration or slightly smaller by the supporting portion of the vibrating body fixture 45. The drive electrode is constituted by a plurality of small drive electrodes 49, and the small drive electrode 49 is a small electrode corresponding to a half wavelength of the bending vibration in the circumferential direction. The small drive electrodes adjacent to each other are polarized in the direction opposite to the thickness direction. And
The outer shape of the small drive electrode 49 is formed to be equal to or slightly smaller than the diameter of the nodal circle of the flexural vibration so as not to interfere with the supporting portion of the vibrating body fixture 45. The piezoelectric body 42 is a small drive electrode 49
The surface shown in FIG.
The vibrating body 43 is formed by sticking them together. Here, when the elastic body 41 has no conductivity, it is necessary to short-circuit the small drive electrodes 49 with each other by means such as sputtering or vapor deposition.

When an AC voltage having a frequency near the resonance frequency of the vibrating body 43 is applied to the circular electrode of the piezoelectric body 42 using the vibrating body 43 as a common electrode, the bending vibration of the displacement distribution 46 shown in FIG. Is done. Here, a radial vibration (primary has no knot circle, secondary has one knot circle) / circumferential tertiary (three circumferential waves) excitation ing.

Since the principle of operation of this embodiment is the same as that of the first embodiment, a detailed description thereof will be omitted. However, as in the first embodiment, the vibrating body 43 is driven to generate flexural vibration. When excited, the moving body 44 starts rotating. And moving body 4
Since the eccentric weight 90 is installed in 4, the piezoelectric vibrator starts to vibrate. In the present embodiment, since the thickness of the vibrating body 43 is constant, the vibrating body 4 having excellent resonance characteristics is provided.
3 can be realized. In addition, since the drive electrode is configured within the area of the nodal circle diameter of the flexural vibration, and the area of the drive electrode is made as large as possible in the area in order to maximize the amount of generated charge, a large driving force can be obtained. it can. Further, since the vibrating body 43 is fixed at the position via the nodal circle portion while avoiding the driving electrode portion, the driving electrode is not deteriorated by the operation, so that the reliability can be improved.

That is, according to the present embodiment, radial secondary / circumferential tertiary bending vibrations, which are driving forces, can be efficiently excited. Further, it is possible to provide an ultrasonic motor realizing both high efficiency, high stability, and high reliability, and a piezoelectric vibrator using the same.

That is, in the present embodiment, since the thickness of the vibrating body is constant, the vibrating body 43 having excellent resonance characteristics can be realized. In addition, since the driving electrodes are configured within the region of the nodal circle of vibration, and the area of the driving electrodes is made as large as possible within the region in order to increase the amount of generated electric charge as much as possible, a large driving force can be obtained. Further, by fixing the position of the vibrating body via the nodal circle, it is possible to provide an ultrasonic motor with reduced vibration loss and a piezoelectric vibrator using the same. Also, since the drive electrode is formed within the nodal circle and the vibrating body 43 is fixed in position via the nodal circle portion, no damage is caused to the drive electrode. Therefore, a highly reliable ultrasonic motor and a highly reliable ultrasonic motor were used. A piezoelectric vibrator can be provided. Here, a brief description has been given of the radial secondary / circumferential tertiary bending motion, but the position at which the sign of the induced charge changes also in the case of radial secondary / circumferential tertiary or higher. Accordingly, the same effect can be obtained by changing the size of the drive electrode.

(Sixth Embodiment) FIG. 11 is a sectional view of an ultrasonic motor and a piezoelectric vibrator using the same according to a sixth embodiment of the present invention. In this embodiment,
The difference from the first embodiment lies in the arrangement of the drive electrodes, as in the fifth embodiment. In the figure, reference numeral 51 denotes a circular elastic body made of a material that easily stores elastic vibration energy such as metal or ceramic, and 52 denotes a circular piezoelectric body made of a material such as single crystal or ceramic. The bodies 52 are bonded to each other with an adhesive such as epoxy resin to form a circular vibrating body 53.
For the same reason as in the fifth embodiment, the outer diameter of the piezoelectric body 52 is made equal to the outer diameter of the elastic body 51. The vibrating body 53 is
At the center thereof, a small hole 58 penetrating the elastic body 51 and the piezoelectric body 52 is provided, and the vibrator fixing member 55 is used to position the vicinity of the small hole 58 and the position of the nodal circle of vibration as in the first embodiment. Position is fixed through both. The elastic body 51 is provided with a projection 57 for taking out output. Reference numeral 54 denotes a moving body made of a material such as metal or plastic, which is installed in pressure contact with a projection 57 formed on the vibrating body 53 as shown in FIG. 60 is a small hole 58
And a rotating shaft that penetrates the vibrator fixture 55 and contacts the moving body 54. Although not necessary in principle of operation, a wear-resistant material may be formed on the surface of the moving body 54 in contact with the vibrating body 53 to improve reliability. May be configured. As described above, the ultrasonic motor according to the present embodiment is configured, and by installing the eccentric weight 90 on a part of the moving body 54, the piezoelectric vibrator according to the present embodiment is obtained.

Displacement distribution 56 of bending vibration excited to vibrating body 53 shown in FIG. 11 in radial secondary / circumferential tertiary or higher (radial secondary / circumferential tertiary bending vibration), and bending The distribution of charges induced in the piezoelectric body 52 by vibration is the same as the distribution shown in FIG. According to FIG. 7, the sign of the induced charge due to the vibration is reversed slightly outside the node circle where the bending vibration amplitude becomes zero. In order to efficiently excite a desired vibration mode, the driving electrode formed on the piezoelectric body 52 may have a total charge induced by vibration as large as possible. Therefore, the drive electrode is formed in a region where the sign of the induced charge is the same and as large as possible. Also, as in the fifth embodiment, the resonance characteristics representing the characteristics of the vibrator 53 as a vibrator are different from those of the elastic member 5.
It is determined by the thickness of the vibrating body 53 which is the sum of 1 and the piezoelectric body 52.
Therefore, in order to improve the characteristics of the vibrating body 53, it is preferable to make the thickness of the vibrating body 53 as constant as possible.

FIG. 12 shows an example of drive electrodes formed on the piezoelectric body 52 constituting the vibrating body 53. The outer shape of the piezoelectric body 52 is equal to the outer shape of the elastic body 51. The back surface of the piezoelectric body surface shown in the figure is a circular solid electrode, and its outer shape is formed to be equal to or slightly smaller than the diameter at which the sign of the induced charge is inverted. The drive electrode is composed of a plurality of small drive electrodes 59, and the small drive electrode 5
Reference numeral 9 denotes a small electrode corresponding to a half wavelength of the bending vibration in the circumferential direction. The small drive electrodes adjacent to each other are polarized in the direction opposite to the thickness direction. The outer shape of the small drive electrode 59 is formed to be equal to or slightly smaller than the diameter at which the sign of the induced charge is inverted. The piezoelectric body 52 is bonded to the elastic body 51 on the surface shown in FIG. Here, when the elastic body 51 has no conductivity, it is necessary to short-circuit the small drive electrodes 59 with each other by means such as sputtering or vapor deposition.

When an AC voltage having a frequency near the resonance frequency of the vibrating body 53 is applied to the solid electrode of the piezoelectric body 52 using the vibrating body 53 as a common electrode, bending vibration of the displacement distribution 56 shown in FIG. You. Here, a radial vibration (primary has no knot circle, secondary has one knot circle) / circumferential tertiary (three circumferential waves) excitation ing.

Since the principle of operation of this embodiment is the same as that of the first embodiment, a detailed description thereof will be omitted. However, as in the first embodiment, the vibration member 53 moves when a bending vibration is excited. Body 54 begins to rotate. Since the eccentric weight 90 is installed on the moving body 54, the piezoelectric vibrator starts to vibrate. In the present embodiment, since the thickness of the vibrating body 53 is constant, the vibrating body 53 having excellent resonance characteristics can be realized. Further, since the driving electrode is formed within a region of a radius where the sign of the induced charge is inverted, and the area of the driving electrode is made as large as possible in the region in order to make the generated charge amount as large as possible, a large driving force is obtained. be able to. Further, by fixing the position of the vibrating body 53 via the nodal circle, it is possible to provide an ultrasonic motor with reduced vibration loss and a piezoelectric vibrator using the same.

In other words, according to the present embodiment, by increasing the amount of induced charges, the radial secondary vibration / circumferential tertiary bending vibration, which is the driving force, can be efficiently and strongly excited. Further, it is possible to provide an ultrasonic motor realizing both high efficiency and high stability and a piezoelectric vibrator using the same.

That is, in the present embodiment, since the thickness of the vibrating body 53 is constant, the vibrating body 53 having excellent resonance characteristics can be realized. In addition, since the driving electrodes are configured within the region where the sign of the charge distribution is inverted, and the area of the driving electrodes is made as large as possible within the region in order to maximize the amount of generated charge, a large driving force is obtained. be able to. That is, according to the present embodiment, radial secondary / circumferential tertiary flexural vibrations, which are driving forces, can be efficiently excited, so that an ultrasonic motor that achieves both high efficiency and high stability, and the use of the ultrasonic motor. A piezoelectric vibrator can be provided.

Here, the bending motion in the radial secondary / circumferential tertiary direction has been specifically described. However, even in the case of radial secondary / circumferential tertiary or higher, the position where the sign of the induced charge changes is not limited. As it changes, the same effect can be obtained by changing the size of the drive electrode.

(Seventh Embodiment) FIG. 13 is a sectional view of an ultrasonic motor and a piezoelectric vibrator using the same according to a seventh embodiment of the present invention. In this embodiment,
The difference from the first embodiment is the arrangement of the drive electrodes. In the figure, reference numeral 61 denotes a circular elastic body made of a material that easily stores elastic vibration energy such as metal or ceramic, and 62 denotes a circular piezoelectric body made of a material such as single crystal or ceramic. The body 62 is bonded to each other with an adhesive such as an epoxy resin to form a circular vibrating body 63. As described later, the piezoelectric body 6
2 has an outer diameter equal to the outer diameter of the elastic body 61. The vibrating body 63 has a small hole 68 at the center thereof that penetrates the elastic body 61 and the piezoelectric body 62, and vibrates with the vicinities of the small holes 48 by vibrating body fixing tool 65, as in the first embodiment. The position is fixed through both the nodal circle positions. The elastic body 61 is provided with a projection 67 for taking out output. Reference numeral 64 denotes a moving body made of a material such as metal or plastic, which is installed in pressure contact with a projection 67 formed on the vibrating body 63 as shown in FIG. 70
Is a rotating shaft that penetrates the small hole 68 and the vibrating body fixture 65 and contacts the moving body 64. Although not necessary in principle of operation, the vibrating body 63 of the moving body 64 is used to improve reliability.
May be made of a wear-resistant material, or the moving body 64 itself may be made of a wear-resistant material. As described above, the ultrasonic motor according to the present embodiment is configured, and by installing the eccentric weight 90 on a part of the moving body 64, the piezoelectric vibrator according to the present embodiment is obtained.

The displacement distribution 66 of the bending vibration exciting the vibrating body 63 shown in FIG. 13 in the radial secondary / circumferential tertiary or higher (here, radial secondary / circumferential tertiary bending vibration), and the bending The distribution of charges induced in the piezoelectric body 62 by vibration is the same as the distribution shown in FIG. According to FIG. 7, the sign of the induced charge due to the vibration is reversed slightly outside the node circle where the bending vibration amplitude becomes zero. In order to efficiently excite a desired vibration mode, the driving electrode formed on the piezoelectric body 62 may have a total charge induced by vibration as large as possible. Therefore, the drive electrode is formed in a region where the sign of the induced charge is the same and as large as possible. Also, as in the fifth embodiment, the resonance characteristics representing the characteristics of the vibrating body 63 as a vibrator are the same as those of the elastic body 6.
It is determined by the thickness of the vibrating body 63 which is the sum of 1 and the piezoelectric body 62.
Therefore, in order to improve the characteristics of the vibrating body 63, it is preferable to make the thickness of the vibrating body 63 as constant as possible.

FIG. 14 shows an example of driving electrodes formed on the piezoelectric body 62 constituting the vibrating body 63. The outer diameter of the piezoelectric body 62 is equal to the outer diameter of the elastic body 61. The back surface of the piezoelectric body surface shown in the figure is a circular solid electrode, the outer diameter of which is substantially equal to the outer diameter of the piezoelectric body 62. The drive electrode shown in FIG. 14 includes a plurality of small drive electrodes 69a and 69b, and each of the small drive electrodes 69a and 69b is a small electrode corresponding to a half wavelength of the bending vibration in the circumferential direction. The small drive electrodes adjacent to each other in the circumferential direction and the small drive electrodes adjacent to each other in the radial direction are polarized in opposite directions in the thickness direction.
The outer diameter of the small drive electrode 69a is equal to or slightly smaller than the diameter at which the sign of the induced charge is reversed, and the inner diameter of the electrode 69b is equal to or slightly larger than the diameter at which the sign of the induced charge is inverted. The diameter is formed equal to or slightly smaller than the outer shape of the piezoelectric body 62. That is, the small drive electrode 69
The boundary between the group a and the group of small drive electrodes 69b is equal to the diameter at which the sign of the induced charge is inverted. The piezoelectric body 62 has a small drive electrode 69a,
The surface shown in FIG. 14 is adhered to the elastic body 61 to form the vibrating body 63 so that the 69b group is short-circuited.
Here, when the elastic body 61 has no conductivity, it is necessary to short-circuit the small drive electrodes 69 with each other by means such as sputtering or vapor deposition.

When an alternating voltage near the resonance frequency of the vibrating body 63 is applied to the solid electrode of the piezoelectric body 62 using the vibrating body 63 as a common electrode, bending vibration of a displacement distribution 66 shown in FIG. . Here, a radial vibration (primary has no knot circle, secondary has one knot circle) / circumferential tertiary (three circumferential waves) excitation ing.

The principle of operation of the present embodiment is the same as that of the first embodiment, and a detailed description thereof will be omitted. In this embodiment, since the thickness of the vibrating body 63 is constant, it is possible to realize the vibrating body 63 having excellent resonance characteristics. Further, by setting the boundary between the small drive electrodes 69a and 69b at the position where the sign of the charge distribution is inverted, the entire area of the piezoelectric body can be effectively used for vibration excitation, and the generated charge amount can be increased, so that a large driving force can be obtained. Can be obtained. That is, according to the present embodiment, radial secondary vibration / circumferential tertiary bending vibration, which is a driving force, can be efficiently excited. Further, it is possible to provide an ultrasonic motor having a large driving force, realizing both high efficiency and high stability, and a piezoelectric vibrator using the same.

That is, in this embodiment, since the thickness of the vibrating body is constant, it is possible to realize a vibrating body having excellent resonance characteristics. In addition, by setting the boundary of the small drive electrode at a position where the sign of the charge distribution is inverted, the entire area of the piezoelectric body can be effectively used for vibration excitation, and the generated charge amount can be increased, so that a large driving force can be obtained. Can be. That is, according to the present embodiment, the radial secondary /
The third-order flexural vibration in the circumferential direction can be efficiently excited. And
It is possible to provide an ultrasonic motor having a large driving force, realizing both high efficiency and high stability, and a piezoelectric vibrator using the same.

Here, the radial secondary / circumferential tertiary bending motion has been briefly described. However, in the case of radial secondary / circumferential tertiary or higher, the position where the sign of the induced charge changes is also described. The same effect can be obtained by changing the boundary of the drive electrode as the value changes.

(Eighth Embodiment) FIG. 15 is a sectional view of an ultrasonic motor and a piezoelectric vibrator using the same according to an eighth embodiment of the present invention. In this embodiment,
The difference from the first embodiment is the arrangement of the drive electrodes. In the figure, reference numeral 71 denotes a circular elastic body made of a material such as metal or ceramic which easily stores elastic vibration energy, and 72 denotes a circular piezoelectric body made of a material such as single crystal or ceramic. The bodies 72 are adhered to each other with an adhesive such as epoxy resin to form a circular vibrating body 73. For the same reason as in the eighth embodiment, the outer diameter of the piezoelectric body 72 is made equal to the outer diameter of the elastic body 71. The vibrating body 73 has a small hole 78 at the center thereof that penetrates the elastic body 71 and the piezoelectric body 72. The position is fixed through both the nodal circle positions. The elastic body 71 has a projection 77 for taking out output.
Is installed. Reference numeral 74 denotes a moving body made of a material such as metal or plastic, which is installed in pressure contact with a projection 77 formed on the vibrating body 73 as shown in FIG. Reference numeral 80 denotes a rotating shaft that penetrates the small hole 78 and the vibrating body fixture 75 and contacts the moving body 74. Although not necessarily required in principle of operation, a wear-resistant material may be formed on the surface of the moving body 74 in contact with the vibrating body 73 in order to improve reliability. May be configured. As described above, the ultrasonic motor according to the present embodiment is configured, and by installing the eccentric weight 90 on a part of the moving body 74, the piezoelectric vibrator according to the present embodiment is obtained.

The displacement distribution 76 of the bending vibration excited in the vibrating body 73 shown in FIG. 15 in the radial secondary / circumferential tertiary or higher (here, radial secondary / circumferential tertiary bending vibration) and the bending The distribution of charges induced in the piezoelectric body 72 by vibration is the same as the distribution shown in FIG. According to FIG. 7, the sign of the induced charge due to the vibration is reversed slightly outside the node circle where the bending vibration amplitude becomes zero. In order to efficiently excite a desired vibration mode, the drive electrode formed on the piezoelectric body 72 should have the total charge induced by the vibration as large as possible. Therefore, the drive electrode is formed in a region where the sign of the induced charge is the same and as large as possible. Further, as in the fifth embodiment, the resonance characteristics representing the characteristics of the vibrator 73 as a vibrator are the same as those of the elastic member 7.
It is determined by the thickness of the vibrating body 73 which is the sum of 1 and the piezoelectric body 72.
Therefore, in order to improve the characteristics of the vibrating body 73, it is preferable to make the thickness of the vibrating body 73 as constant as possible.

FIG. 16 shows an example of both-side drive electrodes formed on the piezoelectric body 72 constituting the vibrator 73. The outer diameter of the piezoelectric body 72 is equal to the outer diameter of the elastic body 71. Two electrodes are formed on the second surface shown in FIG.
The inside diameter of c is slightly larger than the inside diameter of the piezoelectric body 72, the outside diameter is formed equal to or slightly smaller than the node diameter of the bending vibration to be excited, and the inside diameter of the second drive electrode 79d is equal to the node diameter of the bending vibration. The outer diameter is slightly larger than the outer diameter of the piezoelectric body 72. The drive electrode on the first surface shown in FIG. 16A is composed of a plurality of small drive electrodes 79a and 79b, and each of the small drive electrodes 79a and 79b is a small electrode corresponding to a half wavelength of the bending vibration in the circumferential direction. It is. During polarization, the two electrodes 79c and 79d on the second surface of the piezoelectric body 72 are used as common electrodes, and a DC high voltage is applied to the small drive electrodes 79a and 79b on the first surface. The small drive electrodes adjacent to each other in the circumferential direction are polarized in the direction opposite to the thickness direction, and the small drive electrodes adjacent to each other in the radial direction are polarized in the circumferential direction in the thickness direction.

The piezoelectric body 72 has its surface shown in FIG. 16 so that the small drive electrode 79a is short-circuited.
The vibrating body 73 is configured by being bonded to. Here, when the elastic body 71 has no conductivity, it is necessary to short-circuit at least the small drive electrodes 79a to each other by means such as sputtering or vapor deposition. When an AC voltage having a frequency near the resonance frequency of the vibrating body 73 is applied to the electrode 79c of the piezoelectric body 72 using the vibrating body 73 as a common electrode, bending vibration of the displacement distribution 76 shown in FIG. At this time, no voltage is applied to the small drive electrodes 79b and 79d. Here, the radial direction is quadratic (primary has no knot circle, secondary has knot circle of 1
One) / third in the circumferential direction (three waves in the circumferential direction) are excited. The principle of operation of the present embodiment is the same as that of the first embodiment, and a detailed description thereof will be omitted. In the present embodiment, since the thickness of the vibrating body 73 is constant, the vibrating body 73 having excellent resonance characteristics can be realized. Also, the boundaries between the drive electrodes 79a and 79b and the boundaries between the electrodes 79c and 79d are set at the positions of the nodal circle diameter of the flexural vibration. As a result, the amount of generated charges is increased, so that a large driving force can be obtained. In addition, since the entire piezoelectric body is polarized during polarization, the piezoelectric body does not break down mechanically due to distortion during polarization. That is, according to the present embodiment, radial secondary vibration / circumferential tertiary bending vibration, which is a driving force, can be efficiently excited. Further, it is possible to provide an ultrasonic motor realizing both high efficiency, high stability and high reliability, and a piezoelectric vibrator using the same.

That is, in the present embodiment, since the thickness of the vibrating body is constant, it is possible to realize a vibrating body having excellent resonance characteristics. In addition, the boundaries of the drive electrodes on the first surface and the boundaries of the electrodes on the second surface of the piezoelectric body are set at the nodal circle diameter positions of the flexural vibration. As a result, the amount of generated charges is increased, so that a large driving force can be obtained. In addition, since the entire piezoelectric body is polarized during polarization, the piezoelectric body does not break down mechanically due to distortion during polarization. That is, according to the present embodiment, radial secondary vibration / circumferential tertiary bending vibration, which is a driving force, can be efficiently excited. Further, it is possible to provide an ultrasonic motor realizing both high efficiency, high stability and high reliability, and a piezoelectric vibrator using the same.

Here, the bending motion in the radial secondary / circumferential tertiary direction has been briefly described. However, in the case of radial secondary / circumferential tertiary or higher, the nodal circle diameter position of the bending vibration is also considered. The same effect can be obtained by changing the boundary of the drive electrode as the value changes. The same effect can be obtained even if the boundary of the electrode is set at a position near the nodal circle.

(Ninth Embodiment) An ultrasonic motor according to a ninth embodiment of the present invention and a piezoelectric vibrator using the same are shown in FIGS.
6 will be described. This embodiment is different from the eighth embodiment in the arrangement of the drive electrodes, and the other configurations are the same as those in the eighth embodiment. Therefore, the following description focuses on differences from the eighth embodiment, and the description of which is omitted is the same as that of the eighth embodiment.

FIG. 16 shows an example of a double-sided drive electrode formed on the piezoelectric body 72 constituting the vibrator 73. The outer diameter of the piezoelectric body 72 is equal to the outer diameter of the elastic body 71. Two electrodes are formed on the second surface shown in FIG.
The inner diameter of c is slightly larger than the inner diameter of the piezoelectric body 72, the outer diameter is formed equal to or slightly smaller than the diameter at which the sign of the induced charge is inverted, and the inner diameter of the second drive electrode 79d is the diameter at which the sign of the induced charge is inverted. Equal to or slightly larger than the outer diameter of the piezoelectric body 72
Is formed to be slightly smaller than the outer diameter. The drive electrodes on the first surface shown in FIG. 16A are a plurality of small drive electrodes 79a and 79.
b, and the small drive electrodes 79a and 79b are small electrodes each corresponding to a half wavelength of the bending vibration in the circumferential direction. At the time of polarization, two electrodes on the second surface of the piezoelectric body 72 are used as common electrodes, and a DC high voltage is applied to the small drive electrodes 79a and 79b on the first surface. The small drive electrodes adjacent to each other in the circumferential direction are polarized in the direction opposite to the thickness direction, and the small drive electrodes adjacent to each other in the radial direction are polarized in the circumferential direction in the thickness direction.

At the time of driving, as in the eighth embodiment,
An AC voltage having a frequency near the resonance frequency is applied only to the small drive electrodes 79a and 79c, and no voltage is applied to the small drive electrodes 79b and 79d.

In this embodiment, since the thickness of the vibrating body 73 is constant, the vibrating body 73 having excellent resonance characteristics can be realized. Also, the boundaries between the drive electrodes 79a and 79b and the boundaries between the electrodes 79c and 79d are set at positions where the sign of the charge distribution is inverted. As a result, the amount of generated charges is increased, so that a large driving force can be obtained. In addition, since the entire piezoelectric body is polarized during polarization, the piezoelectric body does not break down mechanically due to distortion during polarization. That is, according to the present embodiment, the radial secondary, which is the driving force,
The third-order flexural vibration in the circumferential direction can be efficiently excited. And
An ultrasonic motor realizing both high efficiency, high stability and high reliability and a piezoelectric vibrator using the same can be provided.

That is, in the present embodiment, since the thickness of the vibrating body is constant, it is possible to realize a vibrating body having excellent resonance characteristics. Further, the boundaries of the drive electrodes on the first surface and the boundaries of the electrodes on the second surface of the piezoelectric body are set at positions where the sign of the charge distribution is inverted. As a result, the amount of generated charges is increased, so that a large driving force can be obtained. In addition, since the entire piezoelectric body is polarized during polarization, the piezoelectric body does not break down mechanically due to distortion during polarization. That is, according to the present embodiment, radial secondary vibration / circumferential tertiary bending vibration, which is a driving force, can be efficiently excited. Further, it is possible to provide an ultrasonic motor realizing both high efficiency, high stability and high reliability, and a piezoelectric vibrator using the same.

Here, a brief description has been given of the radial secondary / circumferential tertiary bending motion. However, even in the case of radial secondary / circumferential tertiary or higher, the position where the sign of the induced charge changes. The same effect can be obtained by changing the boundary of the drive electrode as the value changes. The same effect can be obtained even if the boundary of the electrode is set at a position near the nodal circle.

[0088]

As is apparent from the above description, the first to thirteenth aspects of the present invention provide an ultrasonic motor having a small weight, a small thickness, a stable operation, and a high efficiency. The present invention of claim 14 can provide a piezoelectric vibrator using the ultrasonic motor.

[Brief description of the drawings]

FIG. 1 is a sectional view of a piezoelectric vibrator according to a first embodiment of the present invention.

FIG. 2 is a plan view of a driving electrode of a piezoelectric body of the piezoelectric vibrator shown in FIG.

FIG. 3 is a linear model diagram for explaining the operation of the piezoelectric vibrator shown in FIG.

FIG. 4 is a sectional view of a piezoelectric vibrator according to a second embodiment of the present invention.

FIG. 5 is a sectional view of a piezoelectric vibrator according to a third embodiment of the present invention.

FIG. 6 is a sectional view of a piezoelectric vibrator according to a fourth embodiment of the present invention.

7 is a diagram showing a vibration displacement and a charge distribution of the piezoelectric vibrator shown in FIG. 6;

8 is a plan view of a driving electrode of a piezoelectric body of the piezoelectric vibrator shown in FIG.

FIG. 9 is a sectional view of a piezoelectric vibrator according to a fifth embodiment of the present invention.

FIG. 10 is a plan view of a driving electrode of a piezoelectric body of the piezoelectric vibrator shown in FIG. 9;

FIG. 11 is a sectional view of a piezoelectric vibrator according to a sixth embodiment of the present invention.

FIG. 12 is a plan view of a driving electrode of a piezoelectric body of the piezoelectric vibrator shown in FIG. 11;

FIG. 13 is a sectional view of a piezoelectric vibrator according to a seventh embodiment of the present invention.

FIG. 14 is a plan view of a driving electrode of a piezoelectric body of the piezoelectric vibrator shown in FIG.

FIG. 15 is a sectional view of a piezoelectric vibrator according to the eighth and ninth embodiments of the present invention.

16 is a plan view of a drive electrode of a piezoelectric body of the piezoelectric vibrator shown in FIG.

FIG. 17 is a perspective view of a vibrator using a conventional cylindrical electromagnetic motor.

FIG. 18 is a perspective view of a vibrator using a conventional flat electromagnetic motor.

FIG. 19 is a perspective view of a conventional ring-type ultrasonic motor.

FIG. 20 is a plan view showing electrodes of a piezoelectric body of the ring type ultrasonic motor shown in FIG. 19;

21A and 21B are a radial vibration displacement diagram and a vibration appearance diagram of the vibrating body of the ring type ultrasonic motor of FIG.

[Explanation of symbols]

1, 11, 21, 31, 41, 51, 61, 71 Elastic body 2, 12, 22, 32, 42, 52, 62, 72 Piezoelectric body 3, 13, 23, 33, 43, 53, 63, 73 Vibration Body 4, 14, 24, 34, 44, 54, 64, 74 Moving body 5, 15, 25, 35, 45, 55, 65, 75 Vibration body fixture 6, 16, 26, 36, 46, 56, 66 , 76 Displacement distribution 7, 17, 27, 37, 47, 57, 67, 77 Projection body 8, 18, 28, 38, 48, 58, 68, 78 Small hole 9, 39, 49, 59, 69, 79 Small Drive electrode 10, 20, 30, 40, 50, 60, 70, 80 Rotation axis 90 Eccentric weight

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Katsumi Imada, 1006 Kazuma Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd.

Claims (14)

[Claims] 1. A disk-shaped vibrator formed by superposing and connecting a disk-shaped elastic body to a disk-shaped piezoelectric body having drive electrodes on both surfaces, and pressurized contact with said elastic body. And a fixture for fixing the vibrating body, wherein the moving body is configured such that an AC drive voltage applied to the drive electrode is applied to the vibrating body in a radial direction at least two times in a circumferential direction. By exciting a standing wave of bending vibration of third order or more in the direction,
The position at which the fixture rotates and the fixing member fixes the vibrating body is smaller than the case where the bending vibration other than the standing wave to be excited is fixed only at the center of the vibrating body. An ultrasonic motor characterized by being at such a position. 2. The vibrating body has a small hole in the central portion, and the fixing device fixes the vibrating body via the small hole and a node of the bending vibration. The ultrasonic motor according to claim 1, wherein 3. The vibrating body has a small hole in the center portion, and the fixing device is configured such that the fixing member is connected to the vibrating body via the small hole and a part of at least one node diameter portion of the bending vibration. The ultrasonic motor according to claim 1, wherein the ultrasonic motor is fixed. 4. The vibrating body has a small hole in the center portion, and the fixing tool is provided through the small hole and a part of at least one nodal diameter portion and at least one nodal diameter portion of the bending vibration. The ultrasonic motor according to claim 1, wherein the vibrator is fixed. 5. The ultrasonic motor according to claim 1, wherein the piezoelectric body is arranged within a node of the bending vibration. 6. The piezoelectric device according to claim 1, wherein the piezoelectric body is disposed in a region surrounded by a boundary where the sign of the charge induced in the piezoelectric body by the bending vibration is inverted. An ultrasonic motor according to any one of the above. 7. The ultrasonic motor according to claim 1, wherein the piezoelectric body is disposed substantially over the entire area of one surface of the elastic body. 8. The ultrasonic motor according to claim 5, wherein said drive electrode is disposed within a nodal circle of said bending vibration. 9. The device according to claim 6, wherein the drive electrode is disposed in a region surrounded by a boundary where the sign of the charge induced in the piezoelectric body by the bending vibration is inverted. An ultrasonic motor as described. 10. A first drive electrode among the drive electrodes, wherein a first drive electrode is disposed in a region surrounded by a boundary where the sign of a charge induced in the piezoelectric body by the bending vibration is inverted, and a second drive electrode is provided. The ultrasonic motor according to claim 7, wherein the electrode is arranged on an outer peripheral portion of the region. 11. The method according to claim 11, wherein, of the driving electrodes, a first driving electrode is disposed within a node of the bending vibration, and a second driving electrode is disposed at an outer peripheral portion of the node. The ultrasonic motor according to claim 7, wherein 12. The method according to claim 10, wherein the first drive electrode and the second drive electrode are used when the piezoelectric body is polarized, and only the first drive electrode is used when the piezoelectric body is driven. 12. The ultrasonic motor according to 11. 13. The ultrasonic motor according to claim 1, wherein the drive electrode is not in direct contact with the fixture. 14. A piezoelectric vibrator comprising: the ultrasonic motor according to claim 1; and an eccentric weight disposed on the moving body.