JP4945023B2 - Electro-mechanical transducer, ultrasonic motor and electronic equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an energy conversion element using a piezoelectric element and a driving method of the energy conversion element. The present invention also relates to an electronic device using an energy conversion element. For example, a piezoelectric device, that is, an actuator, a sensor, a transformer, a buzzer, a speaker, a filter, and the like, and an electronic device using the piezoelectric device.
[0002]
[Prior art]
In recent years, various piezoelectric devices (for example, actuators, sensors, transformers, filters, etc.) are actively used in various electronic devices. For example, ultrasonic motors are attracting attention among actuators, and application in various fields has been attempted. As a method for driving an ultrasonic motor, a method in which a piezoelectric element is bonded to a plate-like vibrating body and the expansion / contraction motion (by the piezoelectric lateral effect) of the piezoelectric element is converted into bending vibration is generally widely employed. For example, Japanese Patent Publication No. 8-107686 describes an example of such an ultrasonic motor. In this example, the piezoelectric element is divided into two regions, and the driving force is obtained by using one of the regions according to the driving direction of the moving body.
[0003]
When generating bending vibration (displacement) in other actuators, sensors, transformers, buzzers, speakers, etc., or obtaining signals by bending vibration (displacement), bond the piezoelectric element to the elastic member in this way. Is generally done.
[0004]
For example, in the case of a piezoelectric transformer, the piezoelectric element itself is often formed, but polarization processing (thickness direction and longitudinal direction) in different directions is performed to obtain predetermined performance.
[0005]
[Problems to be solved by the invention]
When the above-described method is adopted, workability is poor because a thin piezoelectric element has to be bonded to a vibrating body, and in some cases, the piezoelectric element may be damaged (cracked). And the characteristic dispersion | variation between products by the unevenness of an adhesive agent was easy to arise. Further, since the movement of the piezoelectric element is transmitted to the vibrating body through the adhesive, energy loss occurs in the adhesive. Moreover, since the adhesive is used, the usage environment such as temperature and humidity may be limited. Furthermore, there is a problem that high output driving is difficult due to peeling of the adhesive layer.
[0006]
In the case of the above-described ultrasonic motor, there is a problem that there are few actual parts of the piezoelectric element actually used for driving and the output is small.
[0007]
In addition, since the polarization direction of the conventional piezoelectric transformer is different, residual strain is generated during polarization, and there is a case where breakdown occurs when used at a high output, and electrodes are not provided on the front and back surfaces and side surfaces (end surfaces) of the piezoelectric element. The manufacturing process was complicated.
[0008]
Accordingly, an object of the present invention is to excite a predetermined vibration using only a piezoelectric element and to increase the number of actually used parts of the piezoelectric element so as to increase the output of an actuator, a sensor, a transformer, and the like and to simplify the manufacture.
[0009]
[Means for Solving the Problems]
The present invention includes the feature that made of a piezoelectric element is polarized in the thickness direction to obtain the bending displacement in the thickness direction by applying a electric field between one plurality of electrodes provided in the plane of said piezoelectric element This is an electro-mechanical conversion element.
[0010]
By providing the electrode on one surface, the electric field of the piezoelectric element can be applied on one surface.
[0013]
The present invention is the electromechanical conversion element or the electromechanical conversion element in which the directions of polarization are all the same.
[0014]
Polarization can be easily performed by setting the polarization direction to the same direction.
[0015]
The present invention has a plurality of electrodes provided on one surface of the electro-mechanical conversion element at intervals of 1/2 wavelength of the vibration wave excited by the electro-mechanical conversion element in the circumferential direction. electrical drive signal, characterized in that it is applied between the suit electrodes - a mechanical conversion element.
[0016]
The present invention, the electrical - On the other surface of the transducer, the plurality of electrodes provided on the one surface electrically with a plurality of electrodes shifted 1/4 wave length position relative to the circumferential direction - It is a mechanical conversion element .
[0017]
In the present invention, one surface of an electromechanical conversion element has a plurality of electrodes provided at intervals of 1/4 wavelength of vibration waves excited by the electromechanical conversion element, and two adjacent electrodes the configure multiple electrodes to a pair, a drive signal between the electrode group neighboring characterized in that it is applied electrically - a mechanical conversion element.
[0018]
In the present invention, the polarization direction of the electro-mechanical conversion element is reversed at an interval of ½ wavelength of the vibration wave excited by the electro-mechanical conversion element, and the vibration is applied to one surface of the electro-mechanical conversion element. a plurality of electrodes are provided with a quarter wavelength spacing of the wave, electric wherein the driving signal between the neighboring electrodes is applied - a mechanical conversion element.
[0021]
The present invention is an electronic apparatus including an electro-mechanical conversion element .
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of an energy conversion element, a driving method, and an electronic apparatus using the energy conversion element according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment.
{Embodiment 1}
First, a structural example of an ultrasonic motor applicable to the present invention will be described with reference to FIG. The vibrating body of the ultrasonic motor is composed of a disk-shaped piezoelectric element 1, and a through hole is formed in the center of the piezoelectric element 1. The through hole is supported by a central shaft 3 whose center is fixed to the support plate 4. A plurality of protruding members 2 are provided on the upper surface of the piezoelectric element. The protruding member 2 enlarges the vibration displacement of the vibrating body composed only of the piezoelectric element 1 and gives a rotational force to the moving body 5. The plurality of protrusions 2 a are composed of a base portion 2 b joined at one end thereof and a protruding portion 2 c that protrudes from a part of the base portion 2 b and fits on the guide surface 1 a in the inner diameter portion of the piezoelectric element 1. These projecting members 2 are integrally formed of, for example, wear-resistant engineering plastic and joined to the piezoelectric element 1 by adhesion or the like. Here, the protrusions 2a may be directly joined to the piezoelectric element 1 individually. The piezoelectric element 1 serving as a vibrating body is fixed by a central shaft 3 via a protrusion 2c. Here, the protruding member 2 is bonded to the piezoelectric element 1, but unlike the case of bonding the piezoelectric element and the vibrating body in the conventional example, the bonding force here may be obtained to a certain degree of mechanical strength. The protruding member 2 is bonded onto the piezoelectric element 1 having a structure capable of obtaining a predetermined vibration, and does not cause an imbalance in the vibration of the vibrating body and cause a variation between products.
[0023]
The moving body 5 is disposed above the piezoelectric element 1. A through hole is made in the center of the moving body 5, and the bearing 6 is fixed to the through hole by fitting or bonding. The center of the bearing 6 is guided by the central shaft 3. Therefore, the movable body 5 can rotate around the central axis 3 as a rotation center. Further, a friction member 5 a that contacts the protruding member 2 of the piezoelectric element 1 is provided on the lower surface of the moving body 5.
[0024]
The spring member 7 is provided above the bearing 6 so as to guide the central shaft 3, and the upper portion is fixed with a screw that matches the thread groove received at the central portion of the central shaft 3. By doing so, the inner ring of the bearing 6 can be pressurized, and an appropriate contact pressure can be applied between the protrusion 2 a of the piezoelectric element 1 and the friction member 5 a of the moving body 5. Therefore, the electrical energy applied to the piezoelectric element 1 becomes a vibration wave excited by the vibrating body due to the piezoelectric effect of the piezoelectric element 1. This vibration wave becomes a rotational force of the moving body 5 through a frictional force generated between the protrusion 2a and the friction member 5a of the moving body 5, and is converted into mechanical energy.
[0025]
Next, the operation principle of the ultrasonic motor according to the first embodiment will be described with reference to FIGS. FIG. 2 shows the electrode configuration of the piezoelectric element in this embodiment. 2A shows the first surface of the piezoelectric element 1, and FIG. 2B shows the second surface. Here, the first surface and the second surface have a front-back relationship.
[0026]
Electrodes 8 a and 8 b are disposed on the first surface of the piezoelectric element 1. The electrodes 8a and 8b are equally divided with respect to the circumferential direction of the piezoelectric element 1 at 1/2 wavelength intervals of vibration waves excited by the piezoelectric element 1. The electrodes 8a and 8b are spaced apart so as not to contact each other.
[0027]
Similarly to the first surface, electrodes 9 a and 9 b are provided on the second surface of the piezoelectric element 1.
[0028]
At this time, the electrodes 8a and 8b provided on the first surface and the electrodes 9a and 9b provided on the second surface are half-pitch (1 / day) with respect to the circumferential direction as viewed from the first surface or the second surface. 4 wavelengths).
[0029]
FIG. 3 shows the driving principle in this embodiment.
The piezoelectric element 1 is polarized in one direction in the direction indicated by the arrow P with respect to the thickness direction.
The protrusion 2a is joined to the second surface side at equal intervals at a position shifted by 1/8 wavelength from the node of the standing wave excited by the electrodes 8a, 8b, 9a and 9b. When a drive signal is applied between the electrodes 8a and 8b on the first surface, an electric field is applied from the electrode 8b toward the electrode 8a as indicated by an arrow 100 at a certain moment. By this electric field, the direction of the electric field acts in the thickness direction in the vicinity of the electrodes 8a and 8b with respect to the thickness direction of the piezoelectric element 1, that is, in the vicinity of the surface, and the piezoelectric element 1 expands and contracts according to the relationship between the direction of the electric field and the polarization direction. . Further, in the vicinity of the boundary between the electrode 8a and the electrode 8b, particularly in the portion entering from the surface into the inside, the electric field acts in a direction perpendicular to the polarization direction P, and thus sliding vibration also occurs. However, since the strength of the electric field is increased only on the first surface (electrodes 8a, 8b) side of the piezoelectric element 1, the accompanying displacement also occurs only on the first surface side. Accordingly, a bending standing wave is generated in which a portion bent upward from the stationary position and a portion bent downward from the stationary position appear as shown in FIG. 3B. At this time, since the protrusion 2a is positioned on the right side with respect to the apex of the bending standing wave, the raised protrusion 2a is inclined to the right. On the other hand, the lowered protrusion 2a is inclined leftward. Since the protrusion 2a is in contact with the moving body 5 in FIG. 1, the raised protrusion 2a moves or rotates from the left to the right in the figure.
[0030]
On the other hand, FIG. 3C shows a case where a drive signal is applied between the electrodes 9a and 9b provided on the second surface. When an electric field is applied from the electrode 9b toward the electrode 9a, a bending standing wave is generated in which a portion bent upward from the stationary position and a portion bent downward from the stationary position appear. At this time, since the protrusion 2a is located on the left side with respect to the apex of the bending standing wave, the raised protrusion 2a is inclined to the left, while the lowered protrusion 2a is inclined to the right. Therefore, the moving body 5 moves or rotates from right to left in the figure.
[0031]
Thereby, the moving direction of the moving body 5 can be varied depending on which of the electrodes 8a, 8b on the first surface and the electrodes 9a, 9b on the second surface is applied with a signal. In addition, although the example which used the standing wave was shown above, you may generate | occur | produce a traveling wave in the piezoelectric element 1 used as a vibrating body. At this time, the phase of the signal applied between the electrodes 8a and 8b and the signal applied between the electrodes 9a and 9b may be changed by 90 degrees, for example. Further, in this embodiment, the vibrating body is configured by only the piezoelectric element 1, but it is needless to say that the vibrating body may be configured by being joined to another elastic member.
[0032]
As described above, in this embodiment, it is possible to improve the productivity by causing the bending vibration to be generated only by the piezoelectric element 1 without bonding with the elastic member and by setting the polarization direction to the same direction. . Further, by polarizing in the same direction, there is no boundary portion where the polarization direction is reversed, and the breaking strength is increased. Further, by applying a drive signal to the entire electrode provided on one surface of the piezoelectric element 1 to drive it, stretching vibration due to the piezoelectric lateral effect of the piezoelectric element 1 and thickness slip with a high electro-mechanical coupling coefficient are added. Since vibration is used, an ultrasonic motor with high output and excellent reliability can be obtained. Furthermore, since a drive signal may be applied to the entire electrode provided on one surface, a conduction structure for applying a signal to the piezoelectric element, that is, a lead extraction structure is simplified.
[0033]
As described above, the piezoelectric element 1 of the present embodiment functions as an electro-mechanical conversion element that converts electrical energy into mechanical energy.
{Embodiment 2}
A second embodiment of the present invention will be described with reference to FIG. Hereinafter, since the driving force generation mechanism and its effect are substantially the same as those shown in the first embodiment, only the parts different from the first embodiment such as the configuration will be described.
[0034]
The piezoelectric element 1 is polarized in one direction in the direction of the arrow P with respect to the thickness direction. On the lower surface of the piezoelectric element 1, electrodes 8c, 8d, 8e, and 8f that are equally divided at quarter wavelength intervals of vibration waves excited by the piezoelectric element 1 are provided in the circumferential direction of the piezoelectric element 1. The electrodes 8c, 8d, 8e, and 8f may be provided on the upper surface of the piezoelectric element 1.
The protrusion 2a is joined to a portion corresponding to the center of each of the electrodes 8d and 8f. When a drive signal is applied between the electrodes 8c and 8d and the electrodes 8e and 8f, a standing wave shown in FIG. 4B is generated. At this time, since the protrusion 2a is positioned on the right side with respect to the apex of the bending standing wave, the raised protrusion 2a is tilted to the right, and the moving body 5 moves or rotates from the left to the right in the drawing.
[0035]
When a drive signal is applied between the electrodes 8d and 8e and the electrodes 8c and 8f, a standing wave as shown in FIG. 4C is generated. At this time, since the protrusion 2a is located on the left side with respect to the apex of the bending standing wave, the raised protrusion 2a is tilted to the left, and the moving body 5 moves or rotates from the right to the left in the figure.
[0036]
Thereby, the moving direction of the moving body 5 can be varied by selecting the combination of the electrodes with respect to the drive signal.
[0037]
As described above, the piezoelectric element 1 of the present embodiment functions as an electro-mechanical conversion element that converts electrical energy into mechanical energy.
{Third embodiment}
A third embodiment of the present invention will be described with reference to FIG. The piezoelectric element 1 performs polarization processing in the direction of arrow P with respect to the thickness direction. At this time, the directions of the vibration waves excited by the piezoelectric element 1 are set to be symmetric at every half wavelength. For example, when a portion is polarized from the lower surface to the upper surface, a portion that is one-half wavelength away from the vibration wave is polarized from the upper surface to the lower surface. On the lower surface of the piezoelectric element 1, electrodes 8 g and 8 h that are divided at intervals of ¼ wavelength of the vibration wave excited by the piezoelectric element 1 are provided in the circumferential direction of the piezoelectric element 1. Therefore, the polarization direction is reversed at ½ wavelength intervals at the boundary between the electrodes 8h and 8g.
[0038]
For example, the protrusion 2a is joined to the center of the electrode 8h. When a drive signal is applied between the electrode 8g and the electrode 8h, a standing wave as shown in FIG. 5B is generated. At this time, since the protrusion 2a is located on the left side with respect to the apex of the bending standing wave, the raised protrusion 2a is tilted to the left, and the moving body 5 moves or rotates from the right to the left in the figure.
[0039]
Here, the lengths of the electrodes 8g and 8h are as short as ¼ wavelength, the electric field exerted by the drive signal on the piezoelectric element 1 is large, and a high output drive can be performed at a low voltage.
[0040]
As described above, the piezoelectric element 1 of the present embodiment functions as an electro-mechanical conversion element that converts electrical energy into mechanical energy.
{Embodiment 4}
A fourth embodiment of the present invention will be described with reference to FIGS.
The fourth embodiment relates to an electro-mechanical conversion element comprising the piezoelectric element 1 of the present invention, a piezoelectric transformer using the mechanical-electric conversion element, and an electronic device using the piezoelectric transformer.
[0041]
6A, the rectangular plate-shaped piezoelectric element 1 is provided with electrodes 8i and 8j on the half surface from the center to one end of both the front and back surfaces. In addition, electrodes 8k and 8l are provided at locations from the center to the other end where the electrode 8i on one surface of the piezoelectric element 1 is not provided. An arrow P in the figure indicates the polarization direction, and the polarization direction is reversed across the dotted line. When a drive signal is applied to the electrodes 8i and 8j by the drive circuit 10, the displacement distribution shown by the curve 21 in FIG. 6B is obtained. The piezoelectric element 1 expands and contracts in the longitudinal direction with the center in the longitudinal direction as a node. At this time, a voltage larger than the input voltage is output from the electrodes 8k and 8l to drive the driven object 11. The drive object 11 corresponds to, for example, a backlight of a liquid crystal display and a circuit for driving the backlight, and is mounted in a personal computer (not shown), for example.
[0042]
Here, since all polarization processes are performed in the thickness direction, the voltage required for polarization can be low, and it is difficult to be restricted by production facilities and the like, which facilitates manufacture. The electrodes 8m and 8n are electrodes used for polarization, and may be configured integrally with the electrode 8j. In some cases, the post-polarization voltages 8m and 8n may be removed. Furthermore, since the polarization direction is constant even in the vicinity of the central portion where the stress is maximum, even if it is used at a high output, it becomes strong against destruction. Furthermore, since the size and position of the electrodes 8k and 8l and the gap between them can be set freely, it is possible to adjust the output impedance in accordance with the impedance of the driven object 11 as a load and to set an arbitrary step-up ratio. Is possible. Further, since the polarization direction is only the thickness direction, the electrodes need only be provided on the front and back surfaces of the piezoelectric element 1, and the lamination of the piezoelectric elements 1 can be easily realized. By doing so, various characteristic parameters such as input impedance, output impedance, and step-up ratio can be freely set, and the degree of design freedom can be expanded.
{Embodiment 5}
FIG. 7 shows an example of another embodiment. In the fifth embodiment, the description of the parts common to the contents described in the fourth embodiment will be omitted, and only the differences will be described. As shown by the curve 22 in FIG. 7A, the rectangular plate-shaped piezoelectric element 1 is provided with electrodes 8i and 8j on the half surface from the center to one end of both the front and back surfaces. In addition, electrodes 8k and 8l are provided at locations from the center to the other end where the electrode 8i on one surface of the piezoelectric element 1 is not provided. An arrow P in the figure indicates the polarization direction, and the entire piezoelectric element 1 is polarized in one direction in the thickness direction. When a drive signal is applied to the electrodes 8i and 8j by the drive circuit 10, the piezoelectric element 1 is expanded and contracted in the longitudinal direction with two nodes in the longitudinal direction as nodes as shown in the displacement distribution shown in FIG. 7B. At this time, a voltage larger than the input voltage is output from the electrodes 8k and 8, and the driving object 11 is driven. The driving object 11 corresponds to, for example, a backlight of a liquid crystal display and a circuit for driving the same, and is mounted inside a personal computer (not shown), for example.
[0043]
Here, since all the polarization processes are performed in the thickness direction, the voltage required for the polarization is low, and it is difficult to be restricted by the production equipment and the like, and the manufacturing is facilitated. Furthermore, since the polarization direction is uniform and has no boundary, it is strong against breakdown and can be driven with high output.
[0044]
Further, a common electrode may be provided on the piezoelectric element 1 so that the GND of the driving circuit 10 and the driving object 11 is common. Furthermore, the modification of the present embodiment is arbitrary. For example, the driving electrodes 8i and 8j and the detection electrodes 8k and 8l are provided on the left and right sides of the center of the piezoelectric element 1, but the driving electrodes 8i and 8j May be provided at a position including the central portion of the piezoelectric element 1, and the detection electrodes 8k and 8l may be provided at other portions.
[0045]
As described above, the piezoelectric element 1 of the present embodiment includes an electro-mechanical conversion element that converts electrical energy into mechanical energy, and a mechanical-electrical conversion element that converts mechanical energy into electrical energy. Have both. Therefore, a sensor for measuring acceleration and pressure can be easily realized by using the mechanical-electrical conversion element in the present embodiment.
{Sixth embodiment}
FIG. 8 is a block diagram of a fifth embodiment in which an ultrasonic motor using an electromechanical conversion element according to the present invention is applied to an electronic device.
[0046]
The electronic apparatus includes a vibrating body including the piezoelectric element 1 described above, a moving body 5 driven by the vibrating body, a pressurizing unit 7 that applies contact pressure to the moving body 5 and the vibrating body, and a moving body 5. A movable transmission mechanism 12 and an output mechanism 13 that moves based on the operation of the transmission mechanism 12 are provided.
[0047]
Here, for example, a transmission wheel such as a gear or a friction wheel is used as the transmission mechanism 12, and this is directly formed on the moving body 5. The transmission mechanism 12 may be omitted, and the direct output mechanism 13 may be provided. The output mechanism 12 includes, for example, a pointer, a pointer drive mechanism, a display board such as a calendar, or a display board drive mechanism in an indicating device or an electronic timepiece, and a laser direction in a copier or printer. For cameras and video cameras, a shutter drive mechanism, aperture drive mechanism, lens drive mechanism, film winding mechanism, etc. are used. A slit plate or a filter that transmits only light of a specific wavelength, a contact mechanism or a gap plate that changes a resistance value or a capacitance value for a volume of an acoustic device, and a pickup drive mechanism for a hard disk or an optical disk are used.
[0048]
In addition, if an output shaft is attached to the moving body 5 and a power transmission mechanism that transmits torque from the output shaft is provided, a drive mechanism can be realized by the ultrasonic motor itself.
[0049]
By applying the ultrasonic motor of the present invention to an electronic device, the electronic device can be reduced in voltage, reduced in power consumption, reduced in size, and reduced in cost. Since the ultrasonic motor is used, it is naturally not affected by magnetism and does not generate harmful magnetic noise.
[0050]
【Effect of the invention】
As described above, the present invention configures an actuator to obtain a driving force by applying an electric field between a plurality of electrodes provided on at least one surface of a piezoelectric element polarized in the thickness direction. According to this, since the bending vibration can be generated by a single piezoelectric element, it is not necessary to bond with other elastic members, and it is excellent in reliability and can be manufactured at low cost with little variation between products. Furthermore, since no adhesive is used, the output is increased because a drive signal is applied to the entire electrode provided on one surface of the piezoelectric element, in addition to the increase in mechanical strength.
[0051]
In the case of a sensor or a transformer, the configuration is the same. In this case, by detecting a signal from between electrodes (in the case of a transformer, it may be an input), it is small and large (in the case of a transformer, a high step-up ratio is high). ) Signal is obtained.
[0052]
Furthermore, according to the present invention, an electronic device including the electro-mechanical conversion element or the mechanical-electrical conversion element can be realized, and the electronic device can be reduced in size and power can be saved.
[Brief description of the drawings]
FIG. 1 shows an example of the structure of an ultrasonic motor according to the present invention.
FIG. 2 shows an electrode pattern of a piezoelectric element of an ultrasonic motor according to the present invention.
FIG. 3 shows a first example of the driving principle of the ultrasonic motor of the present invention.
FIG. 4 shows a second example of the driving principle of the ultrasonic motor of the present invention.
FIG. 5 shows a third example of the driving principle of the ultrasonic motor of the present invention.
FIG. 6 shows an example of the structure and operating principle of the piezoelectric transformer of the present invention.
FIG. 7 shows another example of the structure and operating principle of the piezoelectric transformer of the present invention.
FIG. 8 is a block diagram of an electronic apparatus using the ultrasonic motor of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Piezoelectric element 2 Protrusion member 3 Center axis | shaft 4 Support plate 5 Moving body 6 Bearing 7 Pressure mechanism 8, 9 Electrode

Claims (7)

An electro-mechanical conversion element comprising a piezoelectric element polarized in a certain direction in the thickness direction , wherein one surface of the electro-mechanical conversion element has a half wavelength of a vibration wave excited by the electro-mechanical conversion element An electro-mechanical conversion element having a plurality of electrodes provided at intervals, and obtaining a bending displacement by applying a drive signal between adjacent electrodes among the plurality of electrodes . 2. The electrode according to claim 1 , wherein the other surface of the electro-mechanical conversion element has a plurality of electrodes whose positions are shifted by a quarter of a wavelength from the plurality of electrodes provided on the one surface . Electro-mechanical conversion element. An electro-mechanical conversion element composed of a piezoelectric element polarized in a certain direction in the thickness direction, and on one surface of the electro-mechanical conversion element, ¼ of a vibration wave excited by the electro-mechanical conversion element A plurality of electrodes having a plurality of electrodes provided at a wavelength interval are formed, and a plurality of electrode groups each having a pair of two adjacent electrodes are configured, and bending displacement is caused by applying a drive signal between the adjacent electrode groups. electrical and wherein the obtaining - mechanical conversion element. An electro-mechanical conversion element comprising a piezoelectric element polarized in the thickness direction, the polarization direction of the electro-mechanical conversion element being inverted at an interval of 1/2 wavelength of a vibration wave excited by the electro-mechanical conversion element. In addition, a plurality of electrodes are provided on one surface of the electromechanical conversion element at intervals of 1/4 wavelength of the vibration wave, and a bending displacement is obtained by applying a drive signal between the adjacent electrodes. electrical wherein the - mechanical conversion element. An ultrasonic motor comprising the electromechanical conversion element according to any one of claims 1 to 4,
  An ultrasonic motor comprising a moving body driven by the electro-mechanical conversion element. An electronic apparatus comprising the electromechanical conversion element according to claim 1. An electronic apparatus comprising the ultrasonic motor according to claim 5.

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