JP4245096B2 - Multilayer piezoelectric element, piezoelectric actuator using the same, and ultrasonic motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laminated piezoelectric element capable of displacement control with a simple control circuit, and a piezoelectric actuator, piezoelectric sensor, and ultrasonic motor using the same.
[0002]
[Prior art]
FIG. 12 is a structural diagram showing an example of a conventional multilayer piezoelectric element. The multilayer piezoelectric element 1000 includes a plurality of piezoelectric elements 1001 and electrodes 1002 provided between the piezoelectric elements 1001. In general, the piezoelectric longitudinal effect generates approximately twice the displacement under the same electric field as compared with the lateral effect, so that the energy conversion efficiency is high. For this reason, each laminated piezoelectric element 1001 is polarized in the thickness direction. Further, the electrodes 1002 are formed so as to be shifted every other layer and electrically connected in parallel outside. Lamination of the piezoelectric elements 1001 may be performed by bonding, but integration by the green sheet method is more advantageous in terms of reliability and mass productivity, and the piezoelectric elements 1001 can be thinned. When a driving voltage is applied to the stacked piezoelectric element 1000, displacement in the stacking direction can be obtained by expansion and contraction of each piezoelectric element 1001.
[0003]
FIG. 13 is a configuration diagram showing an actuator using a multilayer piezoelectric element. The actuator 1100 includes the multilayer piezoelectric element 1000, a drive circuit 1101 that drives the multilayer piezoelectric element 1000, a control circuit 1102 that controls the drive circuit 1101, and an operation state of the multilayer piezoelectric element 1000 in the control circuit 1102. An operation state detection circuit 1103 for feedback and an instruction unit 1104 for giving an operation instruction signal to the control circuit 1102 are configured. The control circuit 1102 sends a control signal to the drive circuit 1101 in accordance with an instruction from the instruction unit 1104. The drive circuit 1101 applies a predetermined DC voltage to the multilayer piezoelectric element 1000 based on the control signal. The displacement amount of the multilayer piezoelectric element 1000 is detected by the operation state detection circuit 1103 and fed back to the control circuit 1102. The control circuit 1102 sends a control signal to the drive circuit 1101 until the target value is reached.
[0004]
FIG. 14 is a cross-sectional view showing another conventional example of a laminated piezoelectric element, which is disclosed in Japanese Patent Application Laid-Open No. 8-213664. The multilayer piezoelectric element 1000 is applied to a Langevin type ultrasonic motor, and the ultrasonic motor 1200 has a structure in which the multilayer piezoelectric element 1000 is sandwiched between elastic bodies 1201 and 1202 and the center is fixed with a bolt 1203. It becomes. The rotating body 1204 is in pressure contact with the end surface of the elastic body 1201, and the contact pressure is regulated by the tightening force of the bolt 1203 and the elastic force of the spring 1205. When a frequency voltage is applied to the laminated piezoelectric element 1000, the vibration is transmitted to the elastic body 1201, and the rotating body 1204 is rotated by the frictional force between the elastic body 1201 and the rotating body 1204.
[0005]
FIG. 15 is a configuration diagram showing an example of a sensor using a conventional multilayer piezoelectric element. The sensor 1300 is specifically an acceleration sensor or a piezoelectric gyro. This acceleration sensor 1300 has a structure in which a plurality of U-shaped plate-like piezoelectric bodies 1301 are laminated and fired. The acceleration sensor 1300 uses a piezoelectric effect of a piezoelectric element (a voltage is obtained by deformation), and generates a weak current when the two beam portions 1302 and 1303 are bent in a horizontal direction or a vertical direction. ing. If this current is amplified, it can be used as a sensor signal. Further, the number of beam portions 1302 and 1303 is not limited to two and may be three. Thus, according to the ultrasonic motor, actuator, and sensor using the multilayer piezoelectric element 1000, the whole can be reduced in size.
[0006]
[Problems to be solved by the invention]
However, when the conventional multilayer piezoelectric element 1000 is used as an actuator, it has a constant displacement when the voltage applied to each piezoelectric element 1001 is constant. Therefore, a control using a different drive voltage is used to control the amount of displacement. Since the circuit must be used, there is a problem that the circuit configuration becomes complicated.
[0007]
Next, in the ultrasonic motor 1200, if the longitudinal vibration is increased, the torque can be increased, and if the torsional vibration is increased, the number of rotations can be increased. Since the piezoelectric element 1001 has the same thickness, two different frequency voltage generating means are required, and the control circuit is also complicated. Further, the sensor 1300 has a problem in that the size and frequency of the displacement that can be detected are restricted because the thickness of the plate-like piezoelectric body 1301 constituting the multilayer piezoelectric element is the same.
[0008]
Accordingly, the present invention has been made in view of the above, and provides a multilayer piezoelectric element capable of displacement control with a simple control circuit, and a piezoelectric actuator, piezoelectric sensor, and ultrasonic motor using the same. Objective. It is another object of the present invention to provide a piezoelectric sensor that can widen the detection range.
[0009]
[Means for Solving the Problems]
To achieve the above object, the laminated piezoelectric element according to claim 1, the thickness of the piezoelectric element constituting the first laminated piezoelectric element, a piezoelectric element constituting the second laminated piezoelectric element The first and second laminated piezoelectric elements are arranged side by side and integrated .
[0010]
The piezoelectric actuator according to claim 5, and integrating a plurality of laminated piezoelectric element was shall different thickness of the piezoelectric element constituting provided a driving means for applying a voltage to each multi-layer piezoelectric element In addition, control means for controlling the driving means to select a laminated piezoelectric element to which a voltage is applied is provided.
[0011]
According to a sixth aspect of the present invention, there is provided an ultrasonic motor in which a plurality of laminated piezoelectric elements having different thicknesses of piezoelectric elements are integrated, and a vibration converting member is provided on the laminated piezoelectric element. a driving means for applying a voltage to the stacked piezoelectric element, only set and control means for selecting the multi-layer piezoelectric element which applies a voltage to control the drive means of this, by vibrating contacting said vibration converting member The moving body is driven by
[0012]
The ultrasonic motor according to claim 7, the thickness of the piezoelectric element constituting the first laminated piezoelectric element, thinner than the piezoelectric elements constituting the second laminated piezoelectric element, the first and attaching a vibration transducer member to the side of the product layer piezoelectric element in which the integrated with integrated by stacking the second laminated piezoelectric element, further, a driving means for applying a frequency voltage to pair each laminated piezoelectric element the provided, said the first multi-layer piezoelectric element exciting the Tatefu dynamic, the the second multi-layer piezoelectric element exciting the flexural vibration, the vibration conversion member the mobile by vibrating contact with the moving body Is to drive.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.
Embodiment 1 FIG.
1 is a structural diagram showing a multilayer piezoelectric element according to Embodiment 1 of the present invention. The multilayer piezoelectric element 100 has an integrated structure in which a first multilayer piezoelectric element 110 and a second multilayer piezoelectric element 120 are stacked in the thickness direction. The first multilayer piezoelectric element 110 includes a second multilayer piezoelectric element 110. A piezoelectric element 111 thinner than the piezoelectric element 121 constituting the multilayer piezoelectric element 120 is laminated. In the first laminated piezoelectric element 110, an electrode 112 is provided between the piezoelectric elements 111, and every other layer is electrically connected in parallel externally. For the piezoelectric elements 111 and 121, for example, PZT (lead zirconate titanate), barium titanate, titanium oxide, or the like can be used, and any other material that can be deformed when a voltage is applied can be used as appropriate. . The piezoelectric elements 111 and 121 are polarized in the thickness direction. Also in the second laminated piezoelectric element 120, electrodes 122 are provided between the piezoelectric elements 121, and are electrically connected in parallel externally every other layer.
[0030]
A frequency voltage is separately applied to the first laminated piezoelectric element 110 and the second laminated piezoelectric element 120. Specific circuit configurations will be exemplified in the following embodiments. The displacement of the piezoelectric elements 111 and 121 is based on the longitudinal effect. The thinner the thickness, the larger the displacement can be obtained with a lower voltage. For this reason, with the same thickness (the number of stacked layers is different), the first stacked piezoelectric element 110 has a larger displacement than the second stacked piezoelectric element 120.
[0031]
Next, a method for manufacturing the multilayer piezoelectric element 100 will be described. First, an organic solvent, a binder, a plasticizer, and a dispersant are added to the calcined powder, and these are mixed to prepare a slurry. The reason why the calcined powder is used is to prevent dimensional changes due to firing. Subsequently, the slurry is cast on a polyester carrier film with a thickness of about 100 μm. When the slurry is dried, the green sheet is obtained by peeling from the casting film (tape casting method). If this green sheet is used for the first laminated piezoelectric element 110, it is necessary to cast the slurry thicker in order to obtain the green sheet used for the second laminated piezoelectric element 120. In order to change the thickness of the green sheet, the distance between the doctor blade of the tape casting device and the carrier sheet may be increased. Then, this green sheet is punched into a rectangular shape having a predetermined dimension, and an internal electrode conductor paste is formed on one surface thereof. This conductor paste has a thickness of about several μm and can be formed by screen printing. The electrodes 112 and 122 are formed so as to be shifted on the front and back sides of the piezoelectric elements 111 and 121.
[0032]
First, four thicker green sheets are laminated in a mold to form the second laminated piezoelectric element 120, and six thinner green sheets are further laminated thereon and press-molded at high pressure. Thereby, the piezoelectric elements 111 and 121 having different thicknesses are laminated and integrated. The temperature at the time of pressing is about 100 ° C., but this temperature is determined by the softening temperature of the organic binder used. When entering the degreasing process, the organic binder contained is thermally decomposed and removed by raising the temperature to 500 ° C. to 600 ° C. and slowly heating it. Then, it bakes at 1000-1200 degreeC in the electric furnace using a refractory brick. During firing, temperature control is precisely performed so that the error is about 2 ° C. Finally, electrodes 112 and 122 are applied to both surfaces of the laminated piezoelectric elements 111 and 121 and baked. As described above, since the electrodes 112 and 122 are formed so as to be shifted on the front and back of the piezoelectric elements 111 and 121, every other electrode 112 and 122 is short-circuited with respect to the short-circuit electrodes 113 and 123, and is connected in parallel. .
[0033]
As described above, in the multilayer piezoelectric element 100, the combination of the second multilayer piezoelectric element 120 and the first multilayer piezoelectric element 110 facilitates the generation and detection of two or more driving forces and displacements. Further, fine movement (second laminated piezoelectric element 120) and coarse movement (first laminated piezoelectric element 110) are possible without having a complicated drive circuit. In addition, it is possible to detect a small displacement (first stacked piezoelectric element 110) at a high frequency and a large displacement (second stacked piezoelectric element 120) at a low frequency.
[0034]
Embodiment 2. FIG.
FIG. 2 is a structural diagram showing a multilayer piezoelectric element according to Embodiment 2 of the present invention. The multilayer piezoelectric element 200 has a structure in which a first multilayer piezoelectric element 210 and a second multilayer piezoelectric element 220 are integrated in parallel. The first multilayer piezoelectric element 210 includes a second multilayer piezoelectric element 210. A piezoelectric element 211 thinner than the piezoelectric element 221 constituting the piezoelectric element 220 is laminated. Each of the piezoelectric elements 211 and 221 has electrodes 212 and 222 formed on both surfaces thereof, and is polarized in the thickness direction. In this multilayer piezoelectric element 200, for example, when voltages having the same phase are applied, the displacement differs between the first multilayer piezoelectric element 210 and the second multilayer piezoelectric element 220. Therefore, as shown in FIG. The mirror angle can be changed by forming a bridge 250 on the top surface and attaching a mirror 251 to the center. When a voltage having the same phase is applied, the displacement of the first multilayer piezoelectric element 210 is larger than that of the second multilayer piezoelectric element 220. Therefore, the mirror 251 tilts clockwise to change the reflection direction of the light beam L. it can. For example, it can be applied to a laser beam scanning mirror.
[0035]
The multilayer piezoelectric element 200 can be manufactured by a method substantially similar to that of the first embodiment, and the configuration of each of the first and second multilayer piezoelectric elements 210 and 220 is the same as that of the first embodiment. Therefore, detailed description is omitted. The short-circuit electrode 213 interposed between the first laminated piezoelectric element 210 and the second laminated piezoelectric element 220 serves as a common electrode, and is applied in advance before firing. Even with such a configuration, the same effects as described above can be obtained, and the present invention can be applied to various devices (see FIG. 3) using the difference in displacement.
[0036]
Embodiment 3 FIG.
FIG. 4 is a structural diagram showing a multilayer piezoelectric element according to Embodiment 4 of the present invention. The multilayer piezoelectric element 300 has substantially the same structure as that of the multilayer piezoelectric element 100 according to the first embodiment, but the thickness of the piezoelectric element 321 constituting the second multilayer piezoelectric element 320 is the first multilayer piezoelectric element. The difference is that it is an integral multiple (nt: n is an integer) of the thickness (t) of the piezoelectric element 311 constituting the type piezoelectric element 310. Since other than this is the same as that of the first embodiment, the description is omitted. Usually, in order to produce a piezoelectric element having a desired thickness, the thinnest piezoelectric element is produced, and the necessary number of piezoelectric elements are laminated and sintered. For this reason, it becomes easy to manufacture the multilayer piezoelectric element 300 by making it an integral multiple of the basic piezoelectric element.
[0037]
Embodiment 4 FIG.
FIG. 5 is a structural diagram showing a multilayer piezoelectric element according to Embodiment 5 of the present invention. This multilayer piezoelectric element 400 is an integrated combination of three types of multilayer piezoelectric elements 410, 420, and 430 having different thicknesses. The piezoelectric element 411 constituting the first laminated piezoelectric element 410 is half the thickness of the piezoelectric element 421 constituting the second laminated piezoelectric element 420, and the piezoelectric constituting the third laminated piezoelectric element 430. The thickness of the element 431 is half of the thickness of the piezoelectric element 411 constituting the first stacked piezoelectric element 410. Furthermore, the area of the first multilayer piezoelectric element 410 is half the area of the second multilayer piezoelectric element 420, and the area of the third multilayer piezoelectric element 430 is the same as that of the first multilayer piezoelectric element 410. The area is the same as that of the second laminated piezoelectric element 420. The generated force increases as the area of the piezoelectric element increases.
[0038]
Each of the first to third stacked piezoelectric elements 410 to 430 is formed by the process described in the first embodiment. However, the third stacked piezoelectric element 430 has a divided structure, and the divided surface is the first. The first and second stacked piezoelectric elements 410 and 420 are positioned at the same position as the bonding surface. When firing, a conductive paste to be a short-circuit electrode 432 is applied to the divided surface, and the common electrode 412 of the first and second multilayer piezoelectric elements 410 and 420 and the left and right sides of the third multilayer piezoelectric element 430 Common electrode 432. Since the third laminated piezoelectric element 430 has a two-divided structure and can be independently energized, the left side and the right side can be driven independently. Furthermore, since the first and second multilayer piezoelectric elements 410 and 420 can be driven independently, the multilayer piezoelectric element 400 can perform more complicated deformation.
[0039]
Embodiment 6 FIG.
FIG. 6 is a block diagram showing a circuit configuration when the laminated piezoelectric element 100 is applied to a piezoelectric actuator. The piezoelectric actuator 100 includes the first multilayer piezoelectric element 110 and the second multilayer piezoelectric element 120, a first drive circuit 601 for driving the first multilayer piezoelectric element 110, and a second multilayer piezoelectric element. A second drive circuit 602 for driving the element 120, a control circuit 603 for controlling the first drive circuit 601 and the second drive circuit 602, an instruction unit 604 for giving an operation instruction signal to the control circuit 603, and a laminated piezoelectric element 100, an output extraction portion 605 provided in 100, and a fixed support base 606 for fixing and supporting the multilayer piezoelectric element 100.
[0040]
The control circuit 603 sends a control signal to each of the drive circuits 601 and 602 according to an instruction from the instruction unit 604. The drive circuits 601 and 602 apply a predetermined DC voltage to the multilayer piezoelectric element 100 based on the control signal. In addition, the first multilayer piezoelectric element 110 and the second multilayer piezoelectric element 120 are selected by a signal from the instruction unit 604. For example, when the first multilayer piezoelectric element 110 is driven, the first multilayer piezoelectric element 110 is driven. A control signal is sent to the drive circuit 601. As a result, the first laminated piezoelectric element 110 is coarsely displaced. When driving the second multilayer piezoelectric element 120, the second multilayer piezoelectric element 120 is finely displaced by sending a control signal to the second drive circuit 602.
[0041]
FIG. 7 is an explanatory diagram showing a configuration example of an ultrasonic motor to which this piezoelectric actuator is applied. A vibrating body 652 having a protrusion 651 is bonded to the multilayer piezoelectric element 100, and the protrusion tip is formed obliquely. Then, the moving body 653 is disposed to face the protrusion 651. The other surface of the multilayer piezoelectric element 100 is fixed to a fixed support base 606. When the multilayer piezoelectric element 100 is vibrated in this state, the tip of the protrusion 651 continuously contacts the moving body 653 and moves the moving body 653 in one direction. When the first multilayer piezoelectric element 110 is selectively driven by the control circuit 603, the first multilayer piezoelectric element 110 is finely displaced, so that the moving amount of the moving body 653 becomes small. On the other hand, when the second stacked piezoelectric element 120 is selectively driven, the second stacked piezoelectric element 120 is coarsely displaced, so that the moving amount of the moving body 653 increases.
[0042]
Embodiment 7 FIG.
FIG. 8 is a block diagram showing a circuit configuration when the multilayer piezoelectric element is applied to a piezoelectric sensor. FIG. 9 is an explanatory diagram showing a specific configuration example of the piezoelectric actuator. The piezoelectric sensor 700 has a configuration in which the first multilayer piezoelectric element 110 is bonded to one side of the fixed support portion 701 and the second multilayer piezoelectric element 120 is bonded to the other side. The first and second stacked piezoelectric elements 110 and 120 are connected to a detection circuit 702, and a signal transmitted from the detection circuit 702 is amplified and shaped by a signal amplification / shaping circuit 703. The first laminated piezoelectric element 110 can detect a large displacement at a low frequency because each piezoelectric element is thin. The second stacked piezoelectric element 120 can detect a small displacement at a high frequency because each piezoelectric element is thick.
[0043]
Embodiment 8 FIG.
FIG. 10 is a block diagram showing a circuit configuration when the multilayer piezoelectric element is applied to an ultrasonic motor. FIG. 11 is an explanatory diagram illustrating a specific configuration example of the ultrasonic motor. The laminated piezoelectric element 100 is fixed on a support base 802 by a vibrating body support member 801. A vibration conversion member 803 is provided on the side surface of the multilayer piezoelectric element 100, and the vibration conversion member 803 is in contact with the moving body 804. The moving body 804 is pivotally supported by the central shaft 805. The central axis 805 is fixed to the support base 802.
[0044]
The first laminated piezoelectric element 110 excites longitudinal vibration by applying a frequency voltage by the drive circuit 806. In this case, the expansion and contraction motion is caused by utilizing the lateral effect of each piezoelectric element 111 constituting the first stacked piezoelectric element 110. The second laminated piezoelectric element 120 is used as a bimorph displacement element, and when a frequency voltage is applied, one piezoelectric element 121 is contracted and displaced, and the other piezoelectric element 121 is expanded and displaced to excite bending vibration. Let By a combination of the longitudinal vibration and the bending vibration, the vibration converting member 803 performs an elliptical motion with respect to the surface of the moving body 804. The moving body 804 is rotated by the frictional force between the vibration converting member 803 and the moving body 804. In the present embodiment, the case where an ultrasonic motor having a large torque is realized by causing the first multilayer piezoelectric element to expand and contract and the second multilayer piezoelectric element to bend is shown. In addition, it is possible to easily increase the rotational speed by causing the first laminated piezoelectric element to bend and vibrate, and the second laminated piezoelectric element to be expanded and contracted.
[0045]
【The invention's effect】
As described above, according to the multilayer piezoelectric element of the present invention (Claim 1), the displacement amount can be controlled with a simple control circuit by changing the thickness of the piezoelectric elements constituting each integrated multilayer piezoelectric element. Control becomes possible.
[0046]
Next, according to the multilayer piezoelectric element of the present invention (claim 2), the thickness of the piezoelectric element constituting the first multilayer piezoelectric element is made thinner than that of the piezoelectric element constituting the second multilayer piezoelectric element. did. For this reason, the displacement and the driving force can be easily controlled by selecting the first and second stacked piezoelectric elements.
[0047]
Next, in the multilayer piezoelectric element of the present invention (Claim 3), since the first multilayer piezoelectric element and the second multilayer piezoelectric element are arranged in parallel, a complicated displacement can be performed.
[0048]
Next, in the multilayer piezoelectric element according to the present invention (Claim 4), since other multilayer piezoelectric elements having different thicknesses of the piezoelectric elements to be formed are integrated, more complex and precise displacement control becomes possible.
[0049]
Next, the multilayer piezoelectric element of the present invention (Claim 5) is easy to manufacture because the thickness ratio of the piezoelectric elements constituting each multilayer piezoelectric element is an integer value.
[0050]
Next, in the multilayer piezoelectric element of the present invention (Claim 6), since the areas of the multilayer piezoelectric elements are different, the generated force can be controlled in addition to the displacement amount.
[0051]
Next, in the piezoelectric actuator of the present invention (Claim 7), since the displacement amount is controlled by selecting the laminated piezoelectric element to which the voltage is applied, the displacement can be controlled with a simple circuit.
[0052]
Next, in the piezoelectric sensor according to the present invention (Embodiment 8), the detectable range can be widened by using a plurality of stacked piezoelectric elements having different thicknesses.
[0053]
Next, in the ultrasonic motor of the present invention (Claim 9), the movement amount of the moving body can be controlled by selecting the laminated piezoelectric element, and therefore the movement amount can be controlled with a simple circuit.
[0054]
Next, in the ultrasonic motor of the present invention (claim 10), longitudinal vibration is excited by the first laminated piezoelectric element of the integrated laminated piezoelectric element, and bending vibration is produced by the second laminated piezoelectric element. Since the moving body is driven by exciting and bringing the vibration converting member into vibration contact with the moving body, an ultrasonic motor can be configured with a simple structure.
[Brief description of the drawings]
FIG. 1 is a structural diagram showing a multilayer piezoelectric element according to a first embodiment of the present invention.
FIG. 2 is a structural diagram showing a multilayer piezoelectric element according to a second embodiment of the present invention.
FIG. 3 is an explanatory diagram showing a specific application example of the multilayer piezoelectric element of FIG. 2;
FIG. 4 is a structural diagram showing a multilayer piezoelectric element according to a fourth embodiment of the present invention.
FIG. 5 is a structural diagram showing a multilayer piezoelectric element according to a fifth embodiment of the present invention.
FIG. 6 is a block diagram showing a circuit configuration when a multilayer piezoelectric element is applied to a piezoelectric actuator.
7 is an explanatory diagram showing a configuration example of an ultrasonic motor to which the piezoelectric actuator shown in FIG. 6 is applied. FIG.
FIG. 8 is a block diagram showing a circuit configuration when a multilayer piezoelectric element is applied to a piezoelectric sensor.
9 is an explanatory diagram showing a specific configuration example of the piezoelectric actuator shown in FIG. 8. FIG.
FIG. 10 is a block diagram showing a circuit configuration when a laminated piezoelectric element is applied to an ultrasonic motor.
FIG. 11 is an explanatory diagram showing a specific configuration example of the ultrasonic motor shown in FIG. 10;
FIG. 12 is a structural diagram showing an example of a conventional multilayer piezoelectric element.
FIG. 13 is a configuration diagram showing an actuator using a multilayer piezoelectric element.
FIG. 14 is a cross-sectional view showing another conventional example of a laminated piezoelectric element, which is disclosed in Japanese Patent Laid-Open No. 8-213664.
FIG. 15 is a configuration diagram showing an example of a sensor using a conventional multilayer piezoelectric element.
[Explanation of symbols]
100 Laminated Piezoelectric Element 110 First Laminated Piezoelectric Element 111 Piezoelectric Element 112 Electrode 120 Second Laminated Piezoelectric Element 121 Piezoelectric Element 122 Electrode

Claims (7)

The thickness of the piezoelectric element constituting the first laminated piezoelectric element, thinner than the piezoelectric elements constituting the second product layer piezoelectric element, juxtaposed with the first and second laminated pressure conductive elements A laminated piezoelectric element characterized by being integrated. 2. The multilayer piezoelectric element according to claim 1, wherein another multilayer piezoelectric element having a different thickness of the piezoelectric element is integrated in the stacking direction . 2. The multilayer piezoelectric element according to claim 1, wherein a ratio of thicknesses of the piezoelectric elements constituting each multilayer piezoelectric element is an integer value . 2. The multilayer piezoelectric element according to claim 1, wherein the areas of the multilayer piezoelectric elements are different . Multiple stacked piezoelectric elements with different thicknesses of piezoelectric elements If the elements are integrated and driving means for applying voltage to each stacked piezoelectric element is provided Control means for selecting a laminated piezoelectric element that applies a voltage by controlling the drive means. A piezoelectric actuator characterized by comprising: Multiple stacked piezoelectric elements with different thicknesses of piezoelectric elements The element is integrated and a vibration converting member is provided on the laminated piezoelectric element. Driving means for applying a voltage to the multilayer piezoelectric element, and controlling the driving means to Control means for selecting a laminated piezoelectric element to which pressure is applied, and the vibration converting member An ultrasonic motor, wherein a moving body is driven by vibrating contact. The thickness of the piezoelectric element constituting the first stacked piezoelectric element is set to the second product. The first and second stacked pressures are made thinner than the piezoelectric elements constituting the layered piezoelectric element. Electric elements are stacked and integrated, and vibration is applied to the side surface of the integrated multilayer piezoelectric element. A dynamic conversion member is attached, and a frequency voltage is applied to each laminated piezoelectric element. Providing a drive means;
Longitudinal vibration is excited by the first multilayer piezoelectric element, and the second multilayer piezoelectric element By exciting bending vibration and bringing the vibration converting member into vibration contact with the moving body An ultrasonic motor that drives a moving body.

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