JP4269739B2 - Vibration wave motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vibration wave motor whose elastic body has an annular shape with a substantially rectangular cross section.
[0002]
[Prior art]
Conventionally, this type of vibration wave motor generates a progressive vibration wave on the drive surface of the elastic body by utilizing the expansion and contraction of the piezoelectric body, and this traveling wave causes an elliptical motion on the drive surface, and the elliptical motion The mover that is in pressure contact with the wave front is driven (for example, Patent Document 1).
Since such a vibration wave motor has a feature of having a high torque even at a low rotation, when mounted on a drive device, the gear of the drive device can be omitted, so that gear noise can be eliminated or positioning accuracy can be eliminated. There is an advantage that can be improved.
A vibrator of a vibration wave motor using an oscillating traveling wave includes a piezoelectric body and an elastic body, and the piezoelectric body and the elastic body are firmly bonded with an adhesive or the like. The piezoelectric body is provided with silver electrodes on both surfaces by screen printing or the like, and a drive signal is applied to the electrode surfaces.
[0003]
[Patent Document 1]
Japanese Patent Publication No. 1-17354 [0004]
[Problems to be solved by the invention]
In the above-described vibration wave motor, the progressive vibration wave generated in the elastic body is obtained by synthesizing the two standing vibration waves generated by the excitation of the piezoelectric body. The bending vibration of the standing wave is generated by using a stretching force due to voltage application to the piezoelectric body (unimorph effect). For this reason, when there are few electrode parts applied to a piezoelectric body, the force which generate | occur | produces a bending reduces and it may be unable to fully excite bending vibration.
[0005]
Moreover, the elastic body provided with the groove on the driving surface side joins the piezoelectric body to the surface where the groove is not provided by adhesion or the like. When a voltage is applied to the piezoelectric body to cause the elastic body to bend, it is the rigidity of the portion without the groove, that is, the so-called base portion, that determines the magnitude of the bending displacement. The thinner the base portion, the narrower the width, the smaller the rigidity, and the greater the bending displacement when the same bending force is applied from the piezoelectric body.
[0006]
On the other hand, the electrodes applied to the piezoelectric body are usually printed with a gap between the outer diameter end and the inner diameter end in order to prevent short-circuiting on the front and back surfaces caused by protrusions due to printing misalignment. Accordingly, the portion to which the drive signal is applied is reduced by that amount. Along with this, the bending force that the piezoelectric body gives to the elastic body decreases, and the amplitude of the bending vibration may not be sufficient. In that case, there arises a problem that sufficient driving force and driving efficiency cannot be obtained.
[0007]
An object of the present invention is to provide a vibration wave motor capable of improving driving performance such as driving force and driving efficiency.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention of claim 1 is a vibration body having a piezoelectric body excited by a drive signal and an elastic body joined to the piezoelectric body and generating a progressive vibration wave on a drive surface by the excitation. A moving member that is pressed against the driving surface of the elastic body and driven by the progressive vibration wave, and includes a fixing member to which the elastic body is fixed , and the elastic body An annular base portion to which the piezoelectric body is bonded, an extending portion provided on a side of the base portion to which the piezoelectric body is bonded and extending in a radial direction, and the fixing member from the extending portion And a flange portion fixed to the fixing member, and one end in the radial direction of the piezoelectric body is joined to the extending portion, and the width in the radial direction of the piezoelectric body is set to the base. characterized by being larger than the width in the radial direction of the parts Doha is a motor.
According to a second aspect of the present invention, in the vibration wave motor according to the first aspect, the extension portion extends to the inner diameter side of the elastic body, and the inner diameter end of the piezoelectric body is joined to the extension portion. This is a vibration wave motor characterized by that.
[0009]
According to a third aspect of the present invention, in the vibration wave motor according to the first or second aspect, the piezoelectric body has an electrode portion to which a drive signal is applied, and the width of the electrode portion in the radial direction is the base. The vibration wave motor is characterized in that it is larger than the width in the radial direction of the portion and smaller than the width in the radial direction of the piezoelectric body .
The invention according to claim 4, in the vibration wave motor according to claim 2, wherein the piezoelectric element has an electrode unit for applying a driving signal, an inner diameter end of the electrode portion, pressurizing the inside diameter end of said base portion It is a vibration wave motor characterized by being inside the position projected in the pressure direction and outside the inner diameter end of the piezoelectric body .
[0010]
According to a fifth aspect of the present invention, in the vibration wave motor according to the third or fourth aspect , the radial width of the electrode portion is wider than the radial width of the bending center of the elastic body. This is a vibration wave motor.
According to a sixth aspect of the present invention, in the vibration wave motor according to any one of the third to fifth aspects, the piezoelectric body has the surface on the side to which the elastic body is joined and the surface on the opposite side. It is a vibration wave motor characterized by having an electrode part .
[0011]
The invention according to claim 7 is the vibration wave motor according to any one of claims 1 to 5 , wherein the extension portion is a member that holds or protects the piezoelectric body. It is a vibration wave motor.
[0012]
According to an eighth aspect of the present invention, in the vibration wave motor according to any one of the first to sixth aspects, the elastic body is provided on a surface of the base portion opposite to a surface to which the piezoelectric body is bonded. The vibration wave motor includes a plurality of protrusions, and the movable element is in pressure contact with a front end surface of the protrusion.
According to a ninth aspect of the present invention, in the vibration wave motor according to the first aspect, the piezoelectric body has an electrode portion for applying a driving signal, and the side of the base portion to which the piezoelectric body is joined is the base. An extension part extending to the inner diameter side and the outer diameter side of the part, the inner diameter end of the piezoelectric body is joined to the extension part on the inner diameter side, and the outer diameter end of the piezoelectric body is The outer diameter end of the electrode portion is joined to the extension portion on the radial side, and is located on the inner side of the position where the outer diameter end of the base portion is projected in the pressurizing direction, and the outer diameter end of the piezoelectric body It is a vibration wave motor characterized by being inside.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a vibration wave motor according to the present invention will be described below in detail with reference to the accompanying drawings. In the following embodiments, an ultrasonic motor using an ultrasonic vibration region will be described as an example of the vibration wave motor.
(First embodiment)
FIG. 1 is a diagram illustrating an ultrasonic motor according to a first embodiment of the present invention.
The ultrasonic motor 10 according to the first embodiment includes a vibrator 11 and a mover (relative motion member) 14, and the vibrator 11 side is fixed and the mover 14 is driven.
[0014]
As will be described later, the vibrator 11 is obtained by joining a piezoelectric body 12 and an electromechanical transducer (hereinafter referred to as a piezoelectric body) 12 such as a piezoelectric element or an electrostrictive element that converts electrical energy into mechanical energy. And an elastic body 13. Although a traveling wave is generated in the vibrating body 11, this embodiment will be described as a fourth-order traveling wave as an example.
[0015]
The elastic body 13 is made of a metal material having a high resonance sharpness, and has a circular shape with a substantially rectangular cross section. The elastic body 13 is formed with a vibration expanding portion provided with a groove 13a on the opposite surface to which the piezoelectric body 12 is bonded, and the tip surface of the protrusion (between the groove) 13b serves as a driving surface, which moves The child 14 is brought into pressure contact.
The reason for cutting the groove 13a is to make the neutral surface of the traveling wave as close as possible to the piezoelectric body 12 side, thereby amplifying the amplitude of the traveling wave on the drive surface. In the present embodiment, a portion where the groove 13a is not cut is referred to as a base portion 13c. The piezoelectric body 12 is bonded to a surface (bonding surface) opposite to the groove 13a side of the base portion 13c.
[0016]
The base portion 13c is provided with a flange portion 13d and is fixed to the fixing member 16 using the flange portion 13d. The flange portion 13d has a form slightly depending on the drive surface side from the surface to be joined to the piezoelectric body 12.
[0017]
The piezoelectric body 12 is divided into two phases (A phase and B phase) along the circumferential direction, and in each phase, elements with alternating polarization are arranged for every ½ wavelength. A space corresponding to a quarter wavelength is provided between the A phase and the B phase (see FIG. 3).
[0018]
The mover 14 is made of a light metal such as aluminum, and the surface of the sliding surface is subjected to a surface treatment for improving wear resistance.
[0019]
The output shaft 15 is press-fitted into the moving element 14 and rotates integrally with the moving element 14. Bearings 17, 17 are provided between the output shaft 15 and the fixed member 16, and the output shaft 15 and the mover 14 can rotate with respect to the fixed member 16.
[0020]
The pressure member 18 is provided between the two bearings 17 and 17 so that the movable element 14 is in pressure contact with the drive surface of the vibrating body 11. The output shaft 15 is provided with a stopper 19 such as an E clip to determine the axial positions of the bearings 17 and 17 and the pressure member 18.
[0021]
FIG. 2 is a block diagram for explaining the ultrasonic motor drive control apparatus according to the first embodiment. First, the drive control unit of the ultrasonic motor will be described.
The oscillating unit 21 generates a drive signal having a desired frequency according to a command from the control unit 26. The phase shifter 22 divides the drive signal generated by the oscillator 21 into two drive signals having a 90 ° phase difference. The amplification units 23 and 24 boost the two drive signals divided by the phase shift unit 22 to desired voltages, respectively. Drive signals from the amplifying units 23 and 24 are transmitted to the ultrasonic motor 10, and traveling waves are generated in the vibrating body 11 by applying the drive signals, so that the movable element 14 is driven.
[0022]
The detection unit 25 is configured by an optical encoder, a magnetic encoder, or the like, and detects the position and speed of a driven object driven by driving the moving element 14.
The control unit 26 controls driving of the ultrasonic motor 10 based on a driving command from the CPU. The control unit 26 receives the detection signal from the detection unit 25, obtains position information and speed information based on the values, and controls the frequency of the oscillator 21 so as to be positioned at the target position.
[0023]
According to the present embodiment, the ultrasonic motor drive control device operates as follows.
First, the target position is transmitted to the control unit 26. A drive signal is generated from the oscillating unit 21, and the signal is divided into two drive signals having a phase difference of 90 ° by the phase shift unit 22, and is amplified to a desired voltage by the amplification units 23 and 24. The drive signal is applied to the piezoelectric body 12 of the ultrasonic motor 10, and the piezoelectric body 12 is excited. By the excitation, a ninth-order bending vibration is generated in the elastic body 13.
The piezoelectric body 12 is divided into an A phase and a B phase, and drive signals are applied to the A phase and the B phase, respectively. The quaternary bending vibration generated from the A phase and the quaternary bending vibration generated from the B phase are such that the positional phase is shifted by a quarter wavelength, and the A phase driving signal and the B phase driving signal are Is 90 ° out of phase, the two bending vibrations are combined into nine traveling waves.
[0024]
An elliptical motion is generated at the front of the traveling wave. Therefore, the moving element 14 in pressure contact with the driving surface is frictionally driven by this elliptical motion. A detection unit 25 such as an optical encoder is disposed on the driving body (output shaft 15) driven by driving the moving element 14, and an electric pulse is generated therefrom and transmitted to the control unit 26. The control unit 26 can obtain the current position and current speed based on this signal, and the drive frequency of the oscillation unit 21 is controlled based on the position information, speed information, and target position information. Is done.
[0025]
FIG. 3 is a diagram for explaining the piezoelectric body of the ultrasonic motor according to the first embodiment and the electrodes provided on the surface of the piezoelectric body.
Electrodes 12a are provided on the back surface (bonding side) and the front surface (non-bonding side) of the piezoelectric body 12 by silver plating or the like so as to cover each surface, and a drive signal is applied to the entire piezoelectric body 12. It is like that.
However, the electrode 12a is printed with a gap δ from the outer inner diameter portion to prevent printing misalignment of the electrode 12a and to prevent short circuit between the front and back electrodes. As described above, when the width of the electrode 12a is smaller than the width of the piezoelectric body 12, the portion where the bending vibration is actually excited by the drive signal is the portion of the electrode 12a. The piezoelectric body 12 was wasted.
[0026]
When a voltage is applied to the piezoelectric body 12 to cause the elastic body 13 to bend, it is the rigidity of the portion without the groove 13a, that is, the so-called base portion 13c, that determines the magnitude of the bending displacement. The thinner the base part 13c or the narrower the width, the smaller the rigidity. When the same bending force is applied from the piezoelectric body 12, the bending displacement increases. When the piezoelectric body 12 is joined to the base portion 13c of the elastic body 13 having the same width as the piezoelectric body 12, the width of the electrode 12a of the piezoelectric body 12 is narrower than the width of the base portion 13c to be bent. In some cases, a large bending displacement could not be obtained.
[0027]
Therefore, in the present embodiment, the base portion 13c is provided with the extended portion 13e having a diameter larger than that of the base portion 13c with the flange portion 13d as a boundary so that the bending is sufficiently performed. That is, as shown in FIG. 1, when the width of the electrode 12a is w, the outer diameter end of the electrode 12a is outside the position where the outer diameter end of the base portion 13c of the elastic body 13 is projected in the pressurizing direction. The inner diameter end is inside the position where the inner diameter end of the base portion 13c is projected in the pressurizing direction. The radial width w of the electrode 12a is wider than the radial width of the bending center of the elastic body 13.
Since the flange portion 13d is closer to the joint surface side, the rigidity of the base portion 13c depends on the width on the comb tooth side. As a result, the elastic body 13 can obtain a sufficient bending displacement, whereby a sufficient bending vibration amplitude can be obtained, the driving force and the driving efficiency can be improved, and the performance can be improved.
[0028]
In this embodiment, the elastic body 13 is provided with a step portion on the joint surface side of the flange portion 13d, and the portion is an extended portion 13e extending from the base portion 13c to the outer diameter and inner diameter side. The outer diameter end and the inner diameter end of the electrode 12a are in a range in which the extending portion 13e is projected in the pressurizing direction. The extending portion 13 e plays a role of holding or protecting the piezoelectric body 12.
[0029]
In addition, the elastic body 13 needs to be roughened on the bonding surface of the piezoelectric body 12 in order to increase the adhesive strength, and such an extension portion is required to secure the roughening area as much as necessary. It is effective to provide 13e.
When the area to be roughened may be large, the joint surface of the piezoelectric body 12 and the lower surface of the flange portion 13d may be the same surface.
[0030]
(Second embodiment)
FIG. 4 is a diagram for explaining the ultrasonic motor according to the second embodiment.
In the ultrasonic motor 10-2 of the second embodiment, the width of the base portion 13 c below the flange portion 15, that is, the extending portion 13 e is expanded only to the inner diameter side than the width above the flange portion 15. did. Other configurations are the same as those in the first embodiment, and are omitted.
[0031]
In the present embodiment, on the outer diameter side, the gap portion of the electrode 12a of the piezoelectric body 12 overlaps the base portion 13c. On the inner diameter side, the inner diameter of the electrode 12a is arranged on the inner side of the inner diameter side of the base portion 13c. An effect similar to that of the embodiment occurs.
[0032]
(Deformation)
The present invention is not limited to the embodiment described above, and various modifications and changes are possible, and these are also within the equivalent scope of the present invention.
The ultrasonic motor used in each of the above embodiments is a progressive vibration wave of four waves, but the inner diameter or the outer diameter of the electrode portion of the piezoelectric body can be changed from the base portion of the elastic body even with a progressive vibration wave of other wave numbers. By placing them inside or outside, sufficient bending displacement can be obtained, so that sufficient bending vibration amplitude can be obtained, driving force and driving efficiency can be improved, and performance improvement can be obtained. It is done.
[0033]
【The invention's effect】
As described above in detail, according to the present invention, the outer diameter end of the electrode portion is outside the position where the outer diameter end of the base portion of the elastic body is projected in the pressurizing direction and / or the inner diameter thereof. Since the end is inside the position where the inner diameter end of the base portion is projected in the pressurizing direction, sufficient bending displacement can be obtained, and thereby sufficient bending vibration amplitude can be obtained, and driving force and driving Efficiency etc. improve and performance improvement is obtained.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an ultrasonic motor according to a first embodiment of the invention.
FIG. 2 is a block diagram for explaining an ultrasonic motor drive control apparatus according to the first embodiment;
FIG. 3 is a diagram illustrating a piezoelectric body of the ultrasonic motor according to the first embodiment and electrodes provided on the surface of the piezoelectric body.
FIG. 4 is a diagram illustrating an ultrasonic motor according to a second embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Ultrasonic motor 11 Vibrator 12 Piezoelectric body 13 Elastic body 13a Groove 13b Projection part 13c Base part 14 Mover (relative motion member)
DESCRIPTION OF SYMBOLS 15 Output shaft 16 Fixing member 17 Bearing 18 Pressure member 19 Stopper 20 Drive control apparatus 21 Oscillation part 22 Phase shift part 23, 24 Amplification part 25 Detection part 26 Control part

Claims (9)

A piezoelectric body that is excited by a drive signal, and a vibrating body that is bonded to the piezoelectric body and has an elastic body that generates a progressive vibration wave on a driving surface by the excitation;
A mover that is in pressure contact with the drive surface of the elastic body and is driven by the progressive vibration wave;
In a vibration wave motor comprising:
A fixing member to which the elastic body is fixed ;
The elastic body includes an annular base portion to which the piezoelectric body is bonded, an extending portion that is provided on a side of the base portion to which the piezoelectric body is bonded and extends in a radial direction, and the extending portion. Extending in the direction of the fixing member, and having a flange portion fixed to the fixing member,
One end of the piezoelectric body in the radial direction is joined to the extending portion,
A vibration wave motor characterized in that a width in a radial direction of the piezoelectric body is made larger than a width in a radial direction of the base portion. The vibration wave motor according to claim 1,
The extension part extends to the inner diameter side of the elastic body, and the inner diameter end of the piezoelectric body is joined to the extension part;
Vibration wave motor characterized by In the vibration wave motor according to claim 1 or 2,
The piezoelectric body has an electrode portion for applying a drive signal,
The width in the radial direction of the electrode portion is larger than the width in the radial direction of the base portion and smaller than the width in the radial direction of the piezoelectric body;
Vibration wave motor characterized by The vibration wave motor according to claim 2 ,
The piezoelectric body has an electrode portion for applying a drive signal,
The inner diameter end of the electrode portion is inside the position where the inner diameter end of the base portion is projected in the pressurizing direction, and is outside the inner diameter end of the piezoelectric body;
Vibration wave motor characterized by In the vibration wave motor according to claim 3 or 4 ,
The radial width of the electrode portion is wider than the radial width of the bending center of the elastic body;
Vibration wave motor characterized by In the vibration wave motor according to any one of claims 3 to 5 ,
The piezoelectric body has the electrode portion on the surface to which the elastic body is bonded and the opposite surface,
Vibration wave motor characterized by In the vibration wave motor according to any one of claims 1 to 5 ,
The extending portion is a member that holds or protects the piezoelectric body;
Vibration wave motor characterized by The vibration wave motor according to any one of claims 1 to 6,
The elastic body has a plurality of protrusions on a surface of the base portion opposite to a surface to which the piezoelectric body is bonded, and the movable element is in pressure contact with a tip surface of the protrusion;
Vibration wave motor characterized by The vibration wave motor according to claim 1,
The piezoelectric body has an electrode portion for applying a drive signal,
The side of the base portion to which the piezoelectric body is joined has an extending portion extending to the inner diameter side and the outer diameter side of the base portion,
The inner diameter end of the piezoelectric body is joined to the extension portion on the inner diameter side, and the outer diameter end of the piezoelectric body is joined to the extension portion on the outer diameter side,
The outer diameter end of the electrode part is inside the position where the outer diameter end of the base part is projected in the pressurizing direction, and inside the outer diameter end of the piezoelectric body,
Vibration wave motor characterized by

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