JP2000308372A - Laminated piezoelectric element, piezoelectric actuator using the same, piezoelectric sensor and ultrasonic motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control a displacement, using a simple control circuit. SOLUTION: This laminated piezoelectric element 100 is formed as an integrated structure, in which a first laminated piezoelectric element 110 and a second piezoelectric element 120 are stacked in the thickness direction. The first laminated piezoelectric element 110 is formed, in such a way that piezoelectric elements 111 which are thinner than piezoelectric elements 121 constituting the second piezoelectric element 120 are laminated. In the first laminated piezoelectric element 110, electrodes 112 are installed between the respective piezoelectric elements 111, and they are electrically connected in parallel at the outside every other layer. In the piezoelectric elements 111, 112, their polarization is treated in the thickness direction. In addition, even in the second laminated piezoelectric element 120, electrodes 122 are installed between the respective piezoelectric elements 121, and they are electrically connected in parallel at the outside every other layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated piezoelectric element whose displacement can be controlled by a simple control circuit, and a piezoelectric actuator, a piezoelectric sensor and an ultrasonic motor using the same.

[0002]

2. Description of the Related Art FIG. 12 is a structural view showing an example of a conventional laminated piezoelectric element. This laminated piezoelectric element 1000
It comprises a plurality of piezoelectric elements 1001 and electrodes 1002 provided between the piezoelectric elements 1001. In general, the piezoelectric longitudinal effect generates about twice the displacement under the same electric field as compared with the lateral effect, so that the energy conversion efficiency is high. Therefore, each of the laminated piezoelectric elements 1001 is polarized in the thickness direction. Further, the electrodes 1002 are formed so as to be shifted every other layer and are electrically connected in parallel outside. The piezoelectric elements 1001 may be laminated by bonding, but it is more advantageous to integrate them by a green sheet method in terms of reliability and mass productivity, and the thickness of the piezoelectric element 1001 can be reduced. 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.

FIG. 13 is a configuration diagram showing an actuator using a laminated piezoelectric element. This actuator 11
00 denotes the multilayer piezoelectric element 1000, a driving circuit 1101 for driving the multilayer piezoelectric element 1000, and a driving circuit 1
A control circuit 1102 for controlling the control circuit 101;
2, an operation state detection circuit 1103 for feeding back the operation state of the multilayer piezoelectric element 1000, and a control circuit 1102.
And an instruction unit 1104 for giving an operation instruction signal to the control unit. The control circuit 1102 sends a control signal to the drive circuit 1101 according to the instruction from the instruction unit 1104.
The drive circuit 1101 applies a predetermined DC voltage to the multilayer piezoelectric element 1000 based on a control signal. The amount of displacement 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.

FIG. 14 is a cross-sectional view showing another conventional example of the laminated piezoelectric element, which is disclosed in Japanese Patent Application Laid-Open No. Hei 8-213664. The laminated piezoelectric element 1000 is applied to a Langevin type ultrasonic motor. Such an ultrasonic motor 1200 has the laminated piezoelectric element 1000 sandwiched between elastic bodies 1201 and 1202, and the center of which is a bolt 120.
The structure fixed at 3 is obtained. 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 a frictional force between the elastic body 1201 and the rotating body 1204.

FIG. 15 is a configuration diagram showing an example of a sensor using a conventional laminated piezoelectric element. This sensor 1300
Are, specifically, acceleration sensors and piezoelectric gyros. This acceleration sensor 1300 has a structure in which a plurality of U-shaped plate-like piezoelectric members 1301 are stacked and fired. The acceleration sensor 1300 utilizes the piezoelectric effect of a piezoelectric element (obtains a voltage by deforming), and generates a weak current by bending the two beam portions 1302 and 1303 in the horizontal or vertical direction. ing. If this current is amplified, it can be used as a sensor signal. Also,
The number of beam portions 1302 and 1303 is not limited to two, but may be three. As described above, according to the ultrasonic motor, the actuator, and the sensor using the multilayer piezoelectric element 1000,
The whole can be reduced in size.

[0006]

However, in the conventional laminated piezoelectric element 1000, when used as an actuator, the displacement is controlled when the voltage applied to each piezoelectric element 1001 is constant, so that the displacement is controlled. For this purpose, a control circuit using different drive voltages must be used, and there has been a problem that the circuit configuration becomes complicated.

Next, in the ultrasonic motor 1200,
If the longitudinal vibration is strengthened, the torque can be increased, and if the torsional vibration is strengthened, the number of rotations can be increased. For example, when the torque is adjusted by increasing or decreasing the longitudinal vibration, the thickness of the piezoelectric element 1001 is the same. For this reason, two different frequency voltage generating means are required, and the control circuit is also complicated. Further, the sensor 130
0, a plate-like piezoelectric body 1301 constituting a laminated piezoelectric element
However, since the thicknesses are the same, there is a problem that the magnitude and frequency of the displacement that can be detected are restricted.

In view of the above, the present invention has been made in view of the above, and has a laminated piezoelectric element capable of controlling displacement with a simple control circuit, and a piezoelectric actuator using the same.
It is an object to provide a piezoelectric sensor and an ultrasonic motor. It is another object of the present invention to provide a piezoelectric sensor capable of widening a detection range.

[0009]

According to a first aspect of the present invention, there is provided a multi-layer piezoelectric element according to the first aspect of the present invention, wherein a multi-layer piezoelectric element is formed by laminating piezoelectric elements having the same thickness. A piezoelectric element having a different thickness from the element is laminated to form another laminated piezoelectric element, and these laminated piezoelectric elements are integrated.

[0010] When the piezoelectric element is thin, a large displacement can be obtained at a low voltage. For this reason, different displacement amounts can be obtained by changing the thickness of the piezoelectric element constituting each laminated piezoelectric element. This multilayer piezoelectric element is not limited to the case where two sets of multilayer piezoelectric elements are integrated, but may be configured so that three or more sets of multilayer piezoelectric elements are integrated. Further, in integrating three or more sets of laminated piezoelectric elements, the thickness of the constituent piezoelectric elements may be two or more. As described above, by integrating the laminated piezoelectric elements having different thicknesses of the piezoelectric elements, the displacement amount can be controlled only by selecting each laminated piezoelectric element. In addition, complicated displacement control can be performed by selecting each of the stacked piezoelectric elements.

[0011] Further, the laminated piezoelectric element according to claim 2 is
The thickness of the piezoelectric element forming the first multilayer piezoelectric element is smaller than the thickness of the piezoelectric element forming the second multilayer piezoelectric element,
The first and second multilayer piezoelectric elements are integrated in the thickness direction.

Since the first laminated piezoelectric element is formed by laminating the piezoelectric elements thinner than the piezoelectric elements constituting the second laminated piezoelectric element, the first laminated piezoelectric element is formed by the second laminated piezoelectric element. Also, the first stacked piezoelectric element can obtain a larger displacement. When the first and second multilayer piezoelectric elements are stacked in the thickness direction, different displacement amounts can be obtained in the thickness direction. When controlling the amount of displacement, a voltage may be selectively applied to the first stacked piezoelectric element or the second stacked piezoelectric element. By applying a voltage to both the first and second stacked piezoelectric elements, the maximum displacement can be obtained.

[0013] Further, according to a third aspect of the present invention, there is provided a laminated piezoelectric element comprising:
The thickness of the piezoelectric element forming the first multilayer piezoelectric element is smaller than the thickness of the piezoelectric element forming the second multilayer piezoelectric element,
The first and second laminated piezoelectric elements are juxtaposed and integrated.

The displacement of the first multilayer piezoelectric element and the second multilayer piezoelectric element is as described above. Also, by arranging the first and second laminated piezoelectric elements side by side,
Complex displacements can be made. For example, the controlled object can be rocked using the difference in the amount of displacement between the first multilayer piezoelectric element and the second multilayer piezoelectric element. Specific examples thereof will be described in the embodiments.

[0015] Further, the laminated piezoelectric element according to claim 4 is
In the above-mentioned laminated piezoelectric element, another laminated piezoelectric element having a different thickness from the constituent piezoelectric elements is further integrated.

Further, by integrating another laminated piezoelectric element in which piezoelectric elements having different thicknesses are laminated, more complicated and precise displacement control becomes possible.

Further, the laminated piezoelectric element according to claim 5 is
In the above-mentioned laminated piezoelectric element, the ratio of the thickness of the piezoelectric element constituting each of the laminated piezoelectric elements is an integer.

Normally, in order to produce a piezoelectric element having a desired thickness, the thinnest piezoelectric element is prepared and the required number of piezoelectric elements are laminated and sintered. For this reason, by making it an integral multiple of the basic piezoelectric element, it becomes easy to manufacture a laminated piezoelectric element.

Further, the laminated piezoelectric element according to claim 6 is
In the above-mentioned multilayer piezoelectric element, the area of each of the multilayer piezoelectric elements is different.

By changing the area, the force generated by the piezoelectric element is different. For example, when the area of the second multilayer piezoelectric element is larger than the area of the first multilayer piezoelectric element, the generated force is larger in the second multilayer piezoelectric element. Therefore, by selecting the first or second multilayer piezoelectric element, the generated force can be controlled.

In a piezoelectric actuator according to a seventh aspect of the present invention, a driving means for integrating a plurality of laminated piezoelectric elements having different thicknesses of the constituent piezoelectric elements and applying a voltage to each laminated piezoelectric element. And control means for controlling the driving means and selecting a laminated piezoelectric element to which a voltage is applied.

When the thickness of the piezoelectric element is different, the amount of displacement is different even if the same voltage is applied by the driving means. For this reason, the amount of displacement of the piezoelectric actuator can be controlled by selecting which of the stacked piezoelectric elements is applied by the control means. For example, a large displacement can be obtained by applying a voltage to a thinner piezoelectric element, and a smaller displacement can be obtained by applying a voltage to a thicker piezoelectric element. In addition, when a voltage is applied to both laminated piezoelectric elements, the maximum displacement can be obtained.

According to another aspect of the present invention, there is provided a piezoelectric sensor for detecting a plurality of stacked piezoelectric elements having different thicknesses of piezoelectric elements, and an electric signal generated by a piezoelectric effect of each stacked piezoelectric element. A detecting means is provided.

A thin piezoelectric element is suitable for detecting a large displacement at a low frequency because of its high piezoelectric effect. On the other hand, a thick piezoelectric element having a low piezoelectric effect is suitable for detecting small displacement at a high frequency. Therefore, by using a plurality of stacked piezoelectric elements having different thicknesses of the piezoelectric elements, it is possible to widen the detection range. In this case, it is not necessary to integrate the respective laminated piezoelectric elements.

According to a ninth aspect of the present invention, in the ultrasonic motor, 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. Further, a driving unit for applying a voltage to each of the stacked piezoelectric elements, and a control unit for controlling the driving unit and selecting a stacked piezoelectric element for applying the voltage are provided to bring the vibration conversion member into vibration contact. This drives the moving body.

Since the thickness of each of the laminated piezoelectric elements is different from each other, the displacement of the vibration conversion member provided on the laminated piezoelectric element can be reduced by selecting the laminated piezoelectric element to which a voltage is applied. Will be different. In addition, since the moving body moves when the vibration conversion member comes into contact with the moving body, the moving amount of the moving body can be controlled by selecting the laminated piezoelectric element after all. Note that the moving body may be a linear motion as well as a rotary motion.

The ultrasonic motor according to claim 10 is
The thickness of the piezoelectric element forming the first multilayer piezoelectric element is smaller than the thickness of the piezoelectric element forming the second multilayer piezoelectric element,
The first and second multilayer piezoelectric elements are stacked and integrated, a vibration conversion member is attached to a side surface of the integrated multilayer piezoelectric element, and a frequency voltage is applied to each multilayer piezoelectric element. A driving unit is provided to excite longitudinal vibration by the first laminated piezoelectric element, to excite bending vibration by the second laminated piezoelectric element, and to bring the vibration conversion member into vibration contact with a moving body to perform the movement. It drives the body.

The longitudinal vibration caused by the first laminated piezoelectric element and the second vibration
The vibration converting member causes an elliptical motion due to the bending vibration of the laminated piezoelectric element. When the vibration conversion member comes into contact with the moving body, the moving body moves by the frictional force. Note that the moving body may be a linear motion as well as a rotary motion.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. The present invention is not limited by the embodiment. Embodiment 1 FIG. FIG. 1 is a structural diagram illustrating a multilayer piezoelectric element according to a first embodiment of the present invention. The multi-layer piezoelectric element 100 has an integrated structure in which a first multi-layer piezoelectric element 110 and a second multi-layer piezoelectric element 120 are stacked in the thickness direction. The piezoelectric element 111 is thinner than the piezoelectric element 121 of the multilayer piezoelectric element 120. In the first stacked piezoelectric element 110, electrodes 112 are provided between the piezoelectric elements 111, and are electrically connected in parallel outside every other layer. 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 deforms when a voltage is applied thereto 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, the electrodes 122 are provided between the piezoelectric elements 121, and are electrically connected in parallel outside every other layer.

Frequency voltages are separately applied to the first laminated piezoelectric element 110 and the second laminated piezoelectric element 120.
A specific circuit configuration will be described in the following embodiment. The displacement of the piezoelectric elements 111 and 121 uses the longitudinal effect, and the smaller the thickness, the higher the displacement at a lower voltage. Therefore, when the thickness is the same (the number of layers is different), the displacement obtained by the first stacked piezoelectric element 110 is larger than that obtained by the second stacked piezoelectric element 120.

Next, a method of manufacturing the laminated 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 form a slurry. The reason for using the calcined powder is to prevent a dimensional change due to firing.
Subsequently, the slurry is cast on a polyester carrier film to a thickness of about 100 μm. When the slurry has dried, it is peeled off from the casting film to obtain a green sheet (tape casting method).
If this green sheet is used for the first stacked piezoelectric element 110, the slurry needs to be cast thicker to obtain a green sheet used for the second stacked piezoelectric element 120. 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, the green sheet is punched into a rectangular shape having a predetermined size, and a conductive paste for internal electrodes is formed on one surface thereof. This conductive paste has a thickness of about several μm and can be formed by screen printing. Also, the electrodes 112 and 122
Are formed shifted on the front and back of each of the piezoelectric elements 111 and 121.

First, four thicker green sheets are stacked in a mold to form a second stacked piezoelectric element 120, and six thinner green sheets are further stacked thereon, followed by press molding under high pressure. . Thus, the piezoelectric elements 1 having different thicknesses
11 and 121 are laminated and integrated. Pressing temperature is about 1
The temperature is about 00 ° C., but this temperature is determined by the softening temperature of the organic binder used. In the degreasing process, 50
The organic binder contained therein is thermally decomposed and removed by increasing the temperature from 0 ° C. to 600 ° C. and heating it slowly. Then, in an electric furnace using firebricks, 1
Bake at 000-1200 ° C. During firing, the error is 2 ° C
Temperature control is performed precisely to the degree. Finally, electrodes 112 and 122 are provided on both surfaces of the piezoelectric elements 111 and 121 which are laminated.
Apply and bake. As described above, the electrodes 112, 1
Since the electrode 22 is formed so as to be shifted from the front and back of the piezoelectric elements 111 and 121, the electrodes 112 and 122 are short-circuited alternately with the short-circuit electrodes 113 and 123 and are connected in parallel.

As described above, in the multilayer piezoelectric element 100, the second multilayer piezoelectric element 120 and the first multilayer piezoelectric element 11
The combination with zero facilitates the generation and detection of two or more driving forces and displacement amounts. Further, fine movement (the second laminated piezoelectric element 12) can be performed without having a complicated drive circuit.
0) and coarse movement (first multilayer piezoelectric element 110). Further, it is possible to detect a small displacement at a high frequency (first laminated piezoelectric element 110) and a large displacement at a low frequency (second laminated piezoelectric element 120).

Embodiment 2 FIG. 2 is a structural diagram illustrating the multilayer piezoelectric element according to the second embodiment of the present invention. The multi-layer piezoelectric element 200 includes a first multi-layer piezoelectric element 21.
0 and the second multilayer piezoelectric element 220 are integrated in parallel, and the first multilayer piezoelectric element 210 is a piezoelectric element thinner than the piezoelectric element 221 forming the second multilayer piezoelectric element 220. 211 are stacked. Each piezoelectric element 2
The electrodes 11 and 221 have electrodes 212 and 222 formed on both surfaces thereof, and are polarized in the thickness direction.
In this multi-layer piezoelectric element 200, for example, when a voltage having the same phase is applied, the displacement differs between the first multi-layer piezoelectric element 210 and the second multi-layer piezoelectric element 220. Therefore, as shown in FIG. By forming the bridge 250 on the upper surface of the device and attaching the mirror 251 to the center thereof, the mirror angle can be changed. When a voltage having the same phase is applied, the first multilayer piezoelectric element 21 is
Since the displacement of 0 is larger, the mirror 251 can be tilted clockwise to change the reflection direction of the light beam L. For example, the present invention can be applied to a laser light scanning mirror.

The multi-layer piezoelectric element 200 can be manufactured by a method substantially similar to that of the first embodiment. The configuration of each of the first and second multi-layer piezoelectric elements 210 and 220 is the same as that of the first embodiment. Since it is the same, detailed description is omitted. Note that the short-circuit electrode 213 interposed between the first multilayer piezoelectric element 210 and the second multilayer piezoelectric element 220 becomes a common electrode and is applied before firing. Even with such a configuration, the same effects as described above can be achieved, and the invention can be applied to various devices (see FIG. 3) by utilizing the difference in the amount of displacement.

Embodiment 3 FIG. 4 is a structural diagram illustrating a multilayer piezoelectric element according to a fourth embodiment of the present invention. The multilayer piezoelectric element 300 has substantially the same structure as 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
Piezoelectric element 311 constituting first multilayer piezoelectric element 310
In that the thickness is an integral multiple of the thickness (t) (nt: n is an integer). Except for this point, the configuration is the same as that of the first embodiment, and a description thereof will be omitted. Normally, in order to produce a piezoelectric element having a desired thickness, the thinnest piezoelectric element is produced, and the required number of piezoelectric elements are laminated and sintered. For this reason, by making it an integral multiple of the basic piezoelectric element, the multilayer piezoelectric element 300 can be easily manufactured.

Embodiment 4 FIG. FIG. 5 is a structural diagram illustrating a multilayer piezoelectric element according to a fifth embodiment of the present invention. This multilayer piezoelectric element 400 has three types of multilayer piezoelectric elements 410, 420, and 430 in which the thicknesses of the constituent piezoelectric elements are different.
Are combined and integrated. The piezoelectric element 411 constituting the first multilayer piezoelectric element 410 is half the thickness of the piezoelectric element 421 constituting the second multilayer piezoelectric element 420, and the piezoelectric element 411 constituting the third multilayer 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. Further, 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 equal to that of the first multilayer piezoelectric element 410. The area is the same as the area in which the second laminated piezoelectric element 420 is added. The larger the area of the piezoelectric element, the greater the generated force.

Each of the first to third laminated piezoelectric elements 410 to 4
30 is formed by the steps described in the first embodiment. However, the third laminated piezoelectric element 430 has a divided structure, and the divided surfaces are the first and second laminated piezoelectric elements 41.
0, 420 and the same position. When firing, a conductive paste that becomes the short-circuit electrode 432 is applied to the divided surface, and the first and second multilayer piezoelectric elements 410 and 420 are applied.
And the common electrode 432 on the left and right sides of the third laminated piezoelectric element 430. Since the third laminated piezoelectric element 430 is divided into two and has a structure that can be independently energized, the left and right sides can be driven independently. Further, the first and second laminated piezoelectric elements 41
Since the piezoelectric elements 0 and 420 can be driven independently, more complicated deformation can be performed according to the multilayer piezoelectric element 400.

Embodiment 6 FIG. FIG. 6 is a block diagram showing a circuit configuration in the case where the above-mentioned laminated piezoelectric element 100 is applied to a piezoelectric actuator. This piezoelectric actuator 1
00 denotes the first multilayer piezoelectric element 110 and the second multilayer piezoelectric element 120, and the first multilayer piezoelectric element 110
, A second drive circuit 602 for driving the second laminated piezoelectric element 120, a control circuit 603 for controlling the first drive circuit 601 and the second drive circuit 602, and a control circuit 603. , An output unit 605 provided on the multilayer piezoelectric element 100, and a fixed support 606 for fixedly supporting the multilayer piezoelectric element 100.

The control circuit 603 sends a control signal to each of the drive circuits 601 and 602 according to the instruction from the instruction section 604. The drive circuits 601 and 602 apply a predetermined DC voltage to the multilayer piezoelectric element 100 based on a 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. Thereby, the first multilayer piezoelectric element 110 is roughly displaced. When the second multilayer piezoelectric element 120 is driven, a control signal is sent to the second drive circuit 602, whereby the second multilayer piezoelectric element 120 is slightly displaced.

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 projection 651 is joined to the laminated piezoelectric element 100, and the tip of the projection is formed obliquely. Then, the moving body 653 is arranged to face the projection 651. The other surface of the multilayer piezoelectric element 100 is fixed to a fixed support 606. When the multilayer piezoelectric element 100 is vibrated in this state, the tip of the projection 651 continuously contacts the moving body 653, and moves the moving body 653 in one direction. Control circuit 60
When the first multilayer piezoelectric element 110 is selectively driven by the step 3, the first multilayer piezoelectric element 110 is slightly displaced.
The moving amount of the moving body 653 becomes small. On the other hand, when the second multilayer piezoelectric element 120 is selectively driven, the second multilayer piezoelectric element 120 undergoes a coarse movement displacement, so that the moving amount of the moving body 653 increases.

Embodiment 7 FIG. 8 is a block diagram showing a circuit configuration in the case where the above-mentioned laminated piezoelectric element is applied to a piezoelectric sensor. FIG. 9 is an explanatory diagram showing a specific configuration example of this piezoelectric actuator. This piezoelectric sensor 700
The first laminated piezoelectric element 11 is provided on one side of the fixed support portion 701.
0, and a second laminated piezoelectric element 120 is joined to the other side. Further, the first and second multilayer piezoelectric elements 1
Reference numerals 10 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 and shaping circuit 703. The first stacked piezoelectric element 110 can detect a large displacement at a low frequency because each piezoelectric element is thin. The second multilayer piezoelectric element 120 includes:
Since each piezoelectric element is thick, small displacement can be detected at a high frequency.

Embodiment 8 FIG. FIG. 10 is a block diagram showing a circuit configuration in the case where the above-mentioned laminated piezoelectric element is applied to an ultrasonic motor. FIG. 11 is an explanatory diagram showing a specific configuration example of the ultrasonic motor. The multilayer piezoelectric element 100 is fixed on a support base 802 by a vibrating body support member 801. A vibration conversion member 80 is provided on the side surface of the multilayer piezoelectric element 100.
The vibration conversion member 803 is in contact with the moving body 804. The moving body 804 has its central axis 80
5 for pivoting. The central axis 805 is the support base 80
It is fixed to 2.

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 movement is caused by utilizing the lateral effect of each of the piezoelectric elements 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 undergoes contraction displacement and the other piezoelectric element 121 undergoes extension displacement to excite bending vibration. Let it. Due to the combination of the longitudinal vibration and the bending vibration, the vibration conversion 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 conversion member 803 and the moving body 804. In the present embodiment, the first multilayer piezoelectric element expands and contracts,
A case where an ultrasonic motor with a large torque is realized by causing a bending motion with the multilayer piezoelectric element of the above is shown. On the contrary, bending vibration occurs with the first multilayer piezoelectric element, and expansion and contraction occurs with the second multilayer piezoelectric element. It is also possible to easily increase the number of rotations by causing a movement, which corresponds to the present application.

[0045]

As described above, according to the multilayer piezoelectric element of the present invention (claim 1), by changing the thickness of the piezoelectric element constituting each integrated multilayer piezoelectric element,
The displacement amount can be controlled with a simple control circuit.

Next, according to the laminated piezoelectric element of the present invention (claim 2), the thickness of the piezoelectric element constituting the first laminated piezoelectric element is reduced by the thickness of the piezoelectric element constituting the second laminated piezoelectric element. Thinner than Therefore, the displacement and the driving force can be easily controlled by selecting the first and second stacked piezoelectric elements.

Next, in the multi-layer piezoelectric element of the present invention (claim 3), since the first multi-layer piezoelectric element and the second multi-layer piezoelectric element are arranged in parallel, complicated displacement can be performed. .

Next, in the multi-layer piezoelectric element of the present invention (claim 4), since another multi-layer piezoelectric element having a different thickness of the constituting piezoelectric element is integrated, more complicated and precise displacement control is possible. become.

Next, in the laminated piezoelectric element of the present invention (claim 5), the ratio of the thickness of the piezoelectric element constituting each laminated piezoelectric element is set to an integer value, so that it is easy to manufacture.

Next, in the multi-layer piezoelectric element of the present invention (claim 6), since the areas of the multi-layer piezoelectric elements are different, it is possible to control the generated force in addition to the control of the displacement.

Next, in the piezoelectric actuator of the present invention (claim 7), since the displacement is controlled by selecting the laminated piezoelectric element to which a voltage is applied, the displacement can be controlled with a simple circuit. .

Next, in the piezoelectric sensor of the present invention (claim 8), the detection range can be widened by using a plurality of laminated piezoelectric elements having different thicknesses of the piezoelectric elements.

Next, in the ultrasonic motor according to the present invention (claim 9), the moving amount of the moving body can be controlled by selecting the laminated piezoelectric element, so that the moving amount can be controlled with a simple circuit.

Next, in the ultrasonic motor according to the present invention (claim 10), longitudinal vibration is excited by the first laminated piezoelectric element of the integrated laminated piezoelectric element, and the second laminated piezoelectric element is excited by the second laminated piezoelectric element. Since the moving body is driven by exciting the bending vibration and bringing the vibration conversion member into vibration contact with the moving body, the ultrasonic motor can be configured with a simple structure.

[Brief description of the drawings]

FIG. 1 is a structural diagram showing a laminated piezoelectric element according to a first embodiment of the present invention.

FIG. 2 is a structural diagram illustrating 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 illustrating a multilayer piezoelectric element according to a fourth embodiment of the present invention;

FIG. 5 is a structural diagram showing a laminated 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. 8 is a block diagram showing a circuit configuration when a laminated piezoelectric element is applied to a piezoelectric sensor.

FIG. 9 is an explanatory diagram showing a specific configuration example of the piezoelectric actuator shown in FIG. 8;

FIG. 10 is a block diagram showing a circuit configuration in a case where a laminated piezoelectric element is applied to an ultrasonic motor.

11 is an explanatory diagram showing a specific configuration example of the ultrasonic motor shown in FIG.

FIG. 12 is a structural diagram showing an example of a conventional laminated piezoelectric element.

FIG. 13 is a configuration diagram showing an actuator using a laminated piezoelectric element.

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. Hei 8-213664.

FIG. 15 is a configuration diagram showing an example of a sensor using a conventional laminated piezoelectric element.

[Explanation of symbols]

 Reference Signs List 100 laminated piezoelectric element 110 first laminated piezoelectric element 111 piezoelectric element 112 electrode 120 second laminated piezoelectric element 121 piezoelectric element 122 electrode

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H680 AA00 BB01 BB13 BB15 CC02 DD01 DD15 DD23 DD27 DD28 DD37 DD46 DD53 DD67 DD92 DD95 FF23 GG02

Claims (10)

[Claims] 1. A stacked piezoelectric element is formed by stacking piezoelectric elements having the same thickness, and another stacked piezoelectric element is formed by stacking piezoelectric elements having different thicknesses from the piezoelectric element. A laminated piezoelectric element, wherein the laminated piezoelectric element is integrated. 2. The piezoelectric element constituting the first multilayer piezoelectric element is made thinner than the piezoelectric element constituting the second multilayer piezoelectric element, and the first and second multilayer piezoelectric elements are made thinner. Are integrated in the thickness direction. 3. The thickness of a piezoelectric element constituting a first multilayer piezoelectric element is made smaller than the thickness of a piezoelectric element constituting a second multilayer piezoelectric element, and the first and second multilayer piezoelectric elements are formed. Are laminated and integrated. 4. The multi-layer piezoelectric element according to claim 2, wherein another multi-layer piezoelectric element having a different thickness from the multi-layer piezoelectric element is integrated. 5. The method according to claim 2, wherein the ratio of the thickness of the piezoelectric element constituting each of the laminated piezoelectric elements is an integer.
5. The multilayer piezoelectric element according to any one of items 4 to 4. 6. The multi-layer piezoelectric element according to claim 2, wherein the area of each of the multi-layer piezoelectric elements is different. 7. A plurality of laminated piezoelectric elements having different thicknesses of the constituent piezoelectric elements are integrated, a driving means for applying a voltage to each laminated piezoelectric element is provided, and the driving means is controlled. A piezoelectric actuator provided with control means for selecting a laminated piezoelectric element to which a voltage is applied. 8. A multi-layer piezoelectric element having different thicknesses of constituent piezoelectric elements, and a detecting means for detecting an electric signal generated by a piezoelectric effect of each of the multi-layer piezoelectric elements are provided. Piezo sensor. 9. A multi-layer piezoelectric element having different thicknesses of the constituent piezoelectric elements is integrated, a vibration converting member is provided on the multi-layer piezoelectric element, and further, a vibration converting member is provided for each of the multi-layer piezoelectric elements. A driving unit for applying a voltage, and a control unit for controlling the driving unit and selecting a laminated piezoelectric element for applying a voltage are provided, and the moving body is driven by bringing the vibration conversion member into vibration contact. Ultrasonic motor. 10. The thickness of a piezoelectric element constituting a first multilayer piezoelectric element is made smaller than the thickness of a piezoelectric element constituting a second multilayer piezoelectric element, and the first and second multilayer piezoelectric elements are formed. Are stacked and integrated, a vibration conversion member is attached to a side surface of the integrated multilayer piezoelectric element, and drive means for applying a frequency voltage to each multilayer piezoelectric element is provided. Ultrasonic waves, wherein longitudinal vibration is excited by a piezoelectric element, bending vibration is excited by the second laminated piezoelectric element, and the vibration conversion member is brought into vibration contact with the moving body to drive the moving body. motor.