JP2002238269A - Piezoelectric actuator and method of controlling piezoelectric actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To materialize the downsizing of a piezoelectric actuator and its stable driving, and the efficient use of drive voltage by an appropriate constitution of the piezoelectric actuator and its control method. SOLUTION: The piezoelectric actuator consists of a piezoelectric substance 1 where a curved layer 30 having the first electrode part A15, the first polarized part A21 corresponding to the first electrode part A15, the first electrode part B16, the first polarized part B22 corresponding to the first electrode part B16, the second electrode part A17, the second polarized part A23 corresponding to the second electrode part A17, the second electrode part B18, and the second polarized part B24 corresponding to the second electrode part B18, and an elastic layer 29 having the third electrode part 19 and the third polarized part 25 corresponding to the third electrode part 19 are stacked, and there is a GND electrode part 20 between the curved layer 30 and the elastic layer 29. Furthermore, this is provided with the first switch 7 between a drive signal generator 5 and the first electrode part A15, and the second switch 8 between the drive signal generator 5 and the first electrode part B16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a piezoelectric actuator, and more particularly to drive control of a piezoelectric actuator.

[0002]

2. Description of the Related Art Characteristics of a piezoelectric material having the property of an inverse piezoelectric effect in which distortion is generated by the input of electricity include high output, high responsiveness, and non-magnetic properties. There is an ultrasonic motor as an actuator using a piezoelectric body, and in addition to the characteristics of the piezoelectric body, it has a high holding force of a moving body due to frictional force.

[0003] Ultrasonic motors are classified into a standing wave type and a traveling wave type based on the driving principle. It can be configured in a simple shape such as a rectangular plate, a disk, or a column, and can be reduced in size by adopting a configuration utilizing characteristics of the piezoelectric body.

[0004] As a driving method, there is a method in which the moving direction is determined by the elliptical motion direction of the projection provided on the vibrating body in the standing wave type, and the driving method in the traveling wave type. The moving body is driven by the continuous movement of.

[0005] As a configuration of a conventional piezoelectric actuator, a rectangular piezoelectric actuator and a micro piezoelectric actuator will be described in detail with reference to FIGS.

First, a rectangular piezoelectric actuator will be described with reference to FIGS.

The present piezoelectric actuator has a rectangular shape, has a large number of piezoelectric layers, and has a configuration in which the electrodes and the polarization of each layer are different. The laminated structure includes a bending layer 30 for exciting bending vibration and a stretching layer 29 for exciting stretching vibration. The driving combines the bending vibration and the stretching vibration.

The configuration of the rectangular piezoelectric actuator will be described below with reference to FIG.

FIG. 2B shows a bending layer that excites bending vibration among the internal piezoelectric layers of the rectangular piezoelectric actuator.

The bending layer 30 for exciting the bending vibration of the rectangular piezoelectric actuator has a first electrode portion A15 and a first electrode portion B16 as a pair of electrodes, and a second electrode as the other pair of electrodes. Portion A17 and second electrode portion B18
There is. Then, the first electrode portion A15 and the first electrode portion A15
, A first polarization portion B16 corresponding to the first electrode portion B16, a second polarization portion A corresponding to the second electrode portion A17 and a second polarization portion A17 corresponding to the second electrode portion A17.
23, a second electrode portion B18, and a second polarization portion B24 corresponding to the second electrode portion B18.

FIG. 2D shows a stretchable layer that excites stretchable vibration among the internal piezoelectric layers of the rectangular piezoelectric actuator.

The stretching layer 29 for exciting the stretching vibration of the rectangular piezoelectric actuator comprises a third electrode portion 19 and a third electrode portion 19.
And a third polarization section 25 corresponding to

FIG. 2C shows a GND layer serving as an insulating layer with another layer of the rectangular piezoelectric actuator.

The GND layer 31 is formed of a GND layer provided on a piezoelectric body.
It is a layer composed of the D electrode portion 20, sandwiched between the bending layer 30 and the elastic layer 29, and serving to insulate each layer.

FIG. 2A shows one side surface of a long side portion of the rectangular piezoelectric body. On one side surface of the long side of the rectangular piezoelectric body, a first electrode portion B16, a second electrode portion A17, and GND
An electrode unit 20 is provided. In each electrode part, the electrode part provided in the inner layer is drawn out to the side, and the bent layer 3
Even if there are a plurality of 0 and GND layers 31, it is possible to conduct at one time on the side surface.

FIG. 2E shows a long side of a rectangular piezoelectric element.
FIG. 2A shows the other side surface. A first electrode portion A15, a second electrode portion B18, and a third electrode portion 19 are provided on one side surface of the long side of the rectangular piezoelectric body. In each of the electrode portions, the electrode portion provided in the inner layer is drawn out to the side surface, and even if there are a plurality of bending layers 30 and elastic layers 29, it is possible to conduct electricity at the side surface at one time.

A method for driving the rectangular piezoelectric actuator will be described below with reference to FIG.

The rectangular piezoelectric actuator includes a third electrode portion 19, a stretchable layer 29 having a third polarization portion 25 corresponding to the third electrode portion, a first electrode portion A15 and a first electrode portion B16,
The second electrode portion A17, the second electrode portion B18, and the first electrode portion A
15, a first polarized portion A21 at a position corresponding to the first electrode portion B16, a first polarized portion A22 at a position corresponding to the first electrode portion B16,
The second polarization part A2 at a position corresponding to the second electrode part A17
3, a piezoelectric body 1 having a configuration in which a bent layer 30 composed of a second polarization portion B24 located at a position corresponding to the second electrode portion B18, and a GND layer 31 are laminated, and a driving signal source for the piezoelectric body 1 is provided. It comprises a signal generator 5 and a switching unit 6 for switching a position where a voltage is input to the bending layer 30.

In FIG. 3, the first electrode portion A15 and the first electrode portion B provided on the bending layer 30 of the rectangular piezoelectric actuator are shown.
16 shows a case where the switching unit 6 is turned on to the side b so that a voltage is applied to the switching unit 16. When a drive signal is input from the drive signal generator 5 to the first electrode portion A15 and the first electrode portion B16, the piezoelectric body 1 is bent, and as shown in FIG. A secondary vibration with three nodes is excited.

Similarly, when a drive signal is input from the drive signal generator 5 to the third electrode portion 19 provided on the elastic layer 29 of the rectangular piezoelectric actuator, the piezoelectric body 1
The stretching vibration is excited.

The piezoelectric body 1 generates an elliptical motion in each part of the piezoelectric body 1 by combining the bending vibration excited by the bending layer 30 and the stretching vibration excited by the stretching layer 29. Above all, at the tip of the right short side of the piezoelectric body 1 shown in FIG. 3, a counterclockwise elliptical motion is generated, and the moving body 4 is driven by bringing the moving body 4 into contact with the tip of the right short side. It is possible.

Conversely, by setting the direction of the switching section 6 to a, the drive signal is input from the drive signal generator 5 to the second electrode section A17 and the second electrode section B18 in the bending layer 30. Accordingly, the case where the direction of the switching unit 6 is b is
The bending vibration is excited in the opposite phase, and is combined with the stretching vibration by the stretching layer 29, so that a clockwise elliptical motion is generated at the tip of the right short side of the piezoelectric body 1, and the direction of the switching unit 6 is set to b. The moving body 4 can be driven in the opposite direction. That is, by switching the switching unit 6 between a and b, the driving direction of the moving body 4 can be switched.

A micro piezoelectric actuator having an L-shaped vibrator will be described with reference to FIGS.

A micro piezoelectric motor is known as a specific example of a small piezoelectric actuator in which parts of the piezoelectric actuator are manufactured by etching (IEEE 15th Sensor Symposium TECHNICAL DIGEST 181).
Pp. 184 to 1997). FIG. 4 shows an assembly diagram of the micro piezoelectric motor. The micro piezoelectric motor includes a disk-shaped moving body 4 having a rotating shaft 28, a vibrating body 10, and a support 32 that supports the rotating shaft 28. The vibrating body 10 includes a piezoelectric body 1 that generates a stretching motion and an elastic material 9.
There are provided three bending displacement parts 33 attached to. The bending displacement portion 33 has an L-shape, and a short side end of the L-shape is fixed to the center of the support base 32. This bending displacement part 33 is arranged in parallel with the tangential direction of the moving body 4. The moving body 4 has a sliding portion.
The elastic material 9 is manufactured by using etching or the like.

FIG. 5 is an explanatory diagram showing the operation principle of this micro piezoelectric motor. When a driving voltage of a specific frequency is applied to the piezoelectric body 1, the piezoelectric body 1 expands and contracts. Due to the expansion and contraction, the vibrating body 10 bends and vibrates as shown in FIG. When the vibrating body 10 vibrates, the tip of the vibrating body 10 comes into contact with the moving body 4, and the moving body 4 moves by combining the vertical and horizontal force components.

For driving, all the piezoelectric elements 1 shown in FIG.
, A vibration voltage is applied to the bending displacement portion 33 to rotate the moving body 4 about the rotation axis 28.

As described above, the drive characteristics of both the rectangular piezoelectric actuator and the micro piezoelectric motor can be varied depending on the shape at the design stage. And
In order to vary the driving force after the motor is manufactured, the output of the driving signal generator 6, which is the source of the driving signal, is operated by a human hand or the like in an analog manner.

[0028]

In the above-described piezoelectric actuator, a constant driving state is required. When the constant driving state is maintained, only a constant voltage is applied to the piezoelectric actuator. It is possible to meet the demand. However, when the drive characteristics of the drive target fluctuate in time series, it is impossible to keep the drive of the piezoelectric actuator stable while a constant voltage is applied. For this reason, it is common practice to sense the driving state of the piezoelectric actuator with a sensor or the like, to control the voltage value applied to the piezoelectric actuator, or to control the frequency. However, when such a method is adopted, there is a possibility that the driving circuit of the piezoelectric actuator becomes complicated. Therefore, when miniaturizing the entire piezoelectric actuator to the utmost, simplification of the drive circuit also becomes an issue.

In other words, in the case of a piezoelectric actuator, a piezoelectric actuator and a method of driving the piezoelectric actuator that can be controlled efficiently with a simple drive circuit even under the influence of an external load are required.

[0030]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a simple circuit configuration aiming at miniaturization of a piezoelectric actuator.
An object of the present invention is to realize a piezoelectric actuator that can be controlled efficiently and a control method thereof.

The piezoelectric actuator according to the present invention has at least two electrode portions and a polarization portion at a position corresponding to the at least two electrode portions, and moves by applying a voltage to the at least two electrode portions. A piezoelectric actuator having at least one piezoelectric body to be driven, a moving body that is driven in contact with the piezoelectric body, and a drive signal generator that applies a voltage to the at least two electrode sections, wherein the application to the at least two electrode sections is performed. A switching unit for switching between disconnection and conduction of voltage is provided between the at least two electrode units and the drive signal generator.

According to this, a switching section for switching between disconnection and conduction of the voltage applied to at least two electrode portions provided on the piezoelectric body is provided between the at least two electrode portions and the drive signal generator. In addition, the drive characteristics such as the speed and force of the piezoelectric actuator can be controlled by an amount corresponding to the number of voltage application electrodes, and the drive can be controlled only by providing a simple part called a switching unit. Can be simplified, and the configuration of the entire piezoelectric actuator can be reduced in size.

As the piezoelectric material, lead zirconate titanate,
Barium titanate, lithium niobate, lithium tantalate, or the like is used. Further, a sine wave or the like is used as the drive signal.

As the elastic material, metals such as iron, stainless steel, aluminum, beryllium copper, and titanium are used.

The piezoelectric actuator according to the present invention has at least two electrode portions and a polarization portion at a position corresponding to the at least two electrode portions, and moves by applying a voltage to the at least two electrode portions. At least one piezoelectric body, a vibrating body in which the piezoelectric body and the elastic material are joined, a moving body that is driven in contact with the vibrating body, and a drive signal generator that applies a voltage to the at least two electrode units In the piezoelectric actuator, a switching unit that switches between disconnection and conduction of the applied voltage to the at least two electrode units is provided between the at least two electrode units and the drive signal generator.

According to this, not only the same effects as those of the piezoelectric actuator according to the first aspect are expected, but also by forming the vibrating body in which the piezoelectric body and the elastic material are joined, the expansion and contraction motion of the piezoelectric body is reduced. Thus, it is possible to configure a piezoelectric actuator that has converted the bending vibration.

The piezoelectric actuator according to the present invention is characterized in that, in the piezoelectric actuator according to any one of the first to second aspects, the switching unit includes a control unit that instructs switching of voltage disconnection and conduction.

According to this, in addition to the effects of the piezoelectric actuators according to the first and second aspects, a drive signal to the piezoelectric body is provided by further providing the switching section with a control section for instructing switching of voltage disconnection and conduction. Automation of variable level becomes possible.

In the piezoelectric actuator according to the present invention, in the piezoelectric actuator according to any one of claims 1 to 3, a voltage is applied to at least two of the electrode units, and the control unit changes a state in which the moving body is driven. In response to a command to cut off the voltage, the switching unit cuts off the voltage to at least one of the electrode units to which a voltage is applied, and the cut off electrode unit becomes a cutting electrode unit, and the cutting electrode It is characterized in that the moving force of the moving body is reduced by an amount corresponding to the amount of voltage at which the part is disconnected.

According to this, a voltage is applied to at least two electrode portions, and the state in which the moving body is driven is changed from
From the command to cut off the voltage to the switching unit from the control unit, it is possible to set at least one electrode unit provided in the piezoelectric actuator to a state in which no voltage is applied,
Driving characteristics such as the number of revolutions and torque of the piezoelectric actuator can be reduced stepwise by an amount corresponding to the cutting electrode portion.

The piezoelectric actuator according to the present invention is the piezoelectric actuator according to any one of claims 1 to 3, wherein at least one of the electrodes is disconnected from the voltage, and the control unit issues a voltage conduction command. Thereby, the switching unit conducts a voltage to at least one of the electrode units whose voltage is cut off, the electrode unit to which the voltage is applied becomes an application electrode unit, and the applied electrode unit is applied. It is characterized in that the moving force of the moving body is increased by an amount corresponding to the voltage amount.

According to this, from the state where at least one voltage is cut off, the voltage is applied to at least one electrode unit provided on the piezoelectric actuator by the control unit instructing the switching unit to conduct the voltage. It is possible to gradually increase the driving characteristics such as the number of revolutions and torque of the piezoelectric actuator by an amount corresponding to the applied electrode portion.

A piezoelectric actuator according to the present invention is characterized in that, in the piezoelectric actuator according to any one of the first to fifth aspects, a sensor unit for measuring a driving state of the piezoelectric actuator is provided.

According to this, the piezoelectric actuator according to any one of claims 1 to 5 is provided with the sensor section,
The driving state of the piezoelectric actuator can be obtained.

The piezoelectric actuator according to the present invention is characterized in that, in the piezoelectric actuator according to the sixth aspect, the sensor unit measures the speed of the moving body and transmits the speed to the control unit as a measurement signal.

According to this, in the piezoelectric actuator according to the sixth aspect, the sensor unit measures the speed of the moving body and transmits a measurement signal to the control unit, and the control unit transmits the measurement signal based on the measurement signal. It is possible to determine a command to the switching unit.

The piezoelectric actuator according to the present invention is characterized in that, in the piezoelectric actuator according to claim 6, the sensor section measures the acceleration of the moving body and transmits the acceleration to the control section as a measurement signal.

According to this, in the piezoelectric actuator according to the sixth aspect, the sensor unit can measure the acceleration of the moving body and transmit a measurement signal to the control unit. Based on this, it is possible to determine the command to the switching unit.

The piezoelectric actuator according to the present invention is a method for controlling the operation of a piezoelectric actuator according to any one of claims 1 to 8, wherein the sensor unit detects a speed of the moving body; A step in which the sensor unit transmits the speed of the moving body to the control unit as a measurement signal, wherein the control unit determines a change in the speed of the moving body from the measurement signal, and loads an external load on the moving body; The method includes a step of instructing the switching unit to cut off the voltage in response to the decrease in the voltage.

According to this structure, in the piezoelectric actuator according to any one of the first to eighth aspects, the speed of the moving body is detected by the sensor unit, and the load on the moving body from the outside is reduced based on the measurement signal transmitted from the sensor unit. The switching unit instructs the switching unit to cut off the voltage, and the switching unit cuts off the voltage to at least one of the electrode units. It can be reduced by a corresponding amount. As a result, it is possible to maintain the drive characteristics suitable for the reduced load, and it is possible to appropriately control the power consumption. Further, since the drive characteristics can be changed by the switching unit, the drive circuit can be simplified, and the piezoelectric actuator can be reduced in size.

The piezoelectric actuator according to the present invention is a method for controlling the operation of a piezoelectric actuator according to any one of claims 1 to 8, wherein the sensor unit detects a speed of the moving body; A step in which the sensor unit transmits the speed of the moving body to the control unit as a measurement signal, wherein the control unit determines a change in the speed of the moving body from the measurement signal, and loads an external load on the moving body; A step of instructing the switching unit to turn on the voltage in accordance with the increase in the number.

According to this structure, in the piezoelectric actuator according to any one of the first to eighth aspects, the speed of the moving body is detected by the sensor section, and the load on the moving body from the outside is increased based on the measurement signal transmitted from the sensor section. The switching unit instructs the switching unit to conduct voltage, and the switching unit applies a voltage to at least one of the electrode units, so that the driving characteristics such as the rotation speed and torque of the piezoelectric actuator are applied to the cutting electrode unit. It can be increased by a corresponding amount. This makes it possible to maintain the drive characteristics suitable for the increased load and efficiently control the power consumption. Further, since the drive characteristics can be changed by the switching unit, the drive circuit can be simplified, and the overall configuration of the piezoelectric actuator can be reduced in size.

The piezoelectric actuator according to the present invention is a method for controlling the operation of a piezoelectric actuator according to any one of claims 1 to 8, wherein the sensor unit detects an acceleration of the moving body; A step in which the sensor unit transmits the acceleration of the moving body to the control unit as a measurement signal, wherein the control unit determines a change in the acceleration of the moving body from the measurement signal, and loads an external load on the moving body. The method includes a step of instructing the switching unit to cut off the voltage in response to the decrease in the voltage.

According to this, in the piezoelectric actuator according to any one of claims 1 to 8, the acceleration of the moving body is detected by the sensor unit, and the load on the moving body from the outside is reduced based on the measurement signal transmitted from the sensor unit. The switching unit instructs the switching unit to cut off the voltage, and the switching unit cuts off the voltage to at least one of the electrode units. It can be reduced by a corresponding amount. As a result, it is possible to maintain the drive characteristics suitable for the reduced load, and it is possible to appropriately control the power consumption. Further, since the drive characteristics can be changed by the switching unit, the drive circuit can be simplified, and the piezoelectric actuator can be reduced in size.

The piezoelectric actuator according to the present invention is a method for controlling the operation of a piezoelectric actuator according to any one of claims 1 to 8, wherein the sensor unit detects an acceleration of the moving body. A step in which the sensor unit transmits the acceleration of the moving body to the control unit as a measurement signal, wherein the control unit determines a change in the acceleration of the moving body from the measurement signal, and loads an external load on the moving body. A step of instructing the switching unit to turn on the voltage in accordance with the increase in the number.

According to this, in the piezoelectric actuator according to any one of the first to eighth aspects, the acceleration of the moving body is detected by the sensor unit, and the load on the moving body from the outside is increased based on the measurement signal transmitted from the sensor unit. The switching unit instructs the switching unit to conduct voltage, and the switching unit applies a voltage to at least one of the electrode units, so that the driving characteristics such as the rotation speed and torque of the piezoelectric actuator are applied to the cutting electrode unit. It can be increased by a corresponding amount. This makes it possible to maintain the drive characteristics suitable for the increased load and efficiently control the power consumption. Further, since the drive characteristics can be changed by the switching unit, the drive circuit can be simplified, and the overall configuration of the piezoelectric actuator can be reduced in size.

[0057]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Embodiment 1 to which the present invention is applied will be described in detail with reference to FIG.

FIG. 1 is a diagram showing the driving principle of the piezoelectric actuator according to the first embodiment.

The piezoelectric actuator includes a first electrode portion A15
And a first polarized portion A21 corresponding to the first electrode portion A15,
A first electrode portion B16, a first polarization portion B22 corresponding to the first electrode portion B16, a second electrode portion A17, and a second electrode portion A1.
7, the second electrode portion B18, the bent layer 30 having the second electrode portion B18 and the second polarization portion B24 corresponding to the second electrode portion B18, the third electrode portion 19, and the third electrode portion 19. The piezoelectric body 1 is formed by laminating an elastic layer 29 having a corresponding third polarized portion 25. Between the bending layer 30 and the elastic layer 29,
There is a GND electrode section 20. When the drive signal from the drive signal generator 5 is input to the piezoelectric body 1, the piezoelectric body 1
When the bending vibration is excited by the bending layer 30 and the stretching vibration is simultaneously excited by the stretching layer 29, the bending vibration and the stretching vibration combine to draw an elliptical motion at the tip of the piezoelectric body 1, and The moving body 4 can be moved by the contact. FIG. 1 illustrates a state in which the moving body 4 is rotated by providing a rotating shaft 28 at the center of the moving body 4.

Further, in FIG. 1 showing the driving method of the piezoelectric actuator, the first switching section 7 is provided between the drive signal generator 5 and the first electrode section A15, and the drive signal generator 5 and the first electrode section B16 are connected to each other. 2 shows a state in which a second switching unit 8 is provided.

As a result, voltage is applied to both the first electrode portion A15 and the first electrode portion B16,
15 or applying a voltage only to the first electrode portion B, and further applying a voltage to the first electrode portion A
And that no voltage is applied to both the second electrode portion B
The following input means are possible.

In particular, by applying a voltage only to the first electrode portion A15, the first electrode portion A15 and the first electrode portion B16 are applied.
The bending layer 30 that excites the bending vibration by the amount that no voltage is input to the first electrode portion B16 as compared with the case where the voltage is input to
Can be reduced.

Similarly, by applying a voltage only to the first electrode portion B, a voltage is applied to the first electrode portion A15 as compared with a case where a voltage is applied to the first electrode portion A15 and the first electrode portion B16. It is possible to reduce the bending force of the bending layer 30 that excites bending vibration by the amount not to do.

In FIG. 1, the driving signal is conducted to the first electrode unit A15 by the first switching unit 7 and is cut off to the first electrode unit B16 by the second switching unit 8. Is shown. Conversely, the drive signal is conducted to the first electrode portion B16 by the second switching portion 8, and the drive signal is cut off to the first electrode portion A15 by the first switching portion 7 to reduce the bending vibration of the piezoelectric body 1. Control can be performed stepwise.

Although not shown in FIG. 1, the phase of the bending vibration of the bending layer 30 is varied in order to reverse the rotation direction of the moving body 4. For that purpose, a voltage is applied to the second electrode portion A17 and the second electrode portion B18. In this case, similarly to the case where the drive signal is input to the first electrode unit A15 and the first electrode unit B16, the switching unit is connected between the drive signal generator 5, the second electrode unit A17, and the second electrode unit B18. By providing (not shown), the conduction and disconnection of the voltage to the second electrode portion A17 and the second electrode portion B18 can be performed, and the drive characteristics can be changed stepwise.

As described above, in the first embodiment, in the piezoelectric actuator composed of the piezoelectric body having the plurality of electrode portions, the driving signal generator for inputting the driving signal to the electrode portion and the driving portion of the driving signal are provided between the electrode portions. A switching unit for switching between conduction and disconnection is provided corresponding to the electrode unit. This makes it possible to change the drive characteristics of the piezoelectric actuator in a stepwise manner by operating the conduction and disconnection of the drive signal by the switching unit. This makes it possible to vary the driving characteristics of the piezoelectric actuator with a simple configuration, and thus to reduce the size of the piezoelectric actuator.

Embodiment 2 Embodiment 2 of the present invention will be described in detail with reference to FIGS.

FIG. 6 is a block diagram showing the configuration of the piezoelectric actuator according to the second embodiment.

The piezoelectric actuator includes a first electrode portion A15
A first polarization part A21 corresponding to the first electrode part A15,
A first electrode portion B16, a piezoelectric body 1 provided with a first polarization portion B22 corresponding to the first electrode portion B16, a drive signal generator 5 for generating a drive signal, a first electrode portion A15, and a drive signal generator 5, the first switching unit 7 that switches between conduction and disconnection of the drive signal flow, the first electrode unit B16, and the drive signal generator 5
The second switching unit 8 switches between conduction and disconnection of the drive signal, a control unit 11 that performs conduction and disconnection commands to the first switching unit 7 and the second switching unit 8, and the piezoelectric body 1 The moving body 4 is in contact with and moves by the movement of the piezoelectric body 1. Control unit 1
In 1, conduction and disconnection can be controlled independently of each other by the first switching unit 7 and the second switching unit 8.

The number of electrode portions and the number of polarization portions corresponding thereto are not limited to two, but a large number of them are provided on the piezoelectric body 1 and a switching portion is provided in accordance therewith, so that the piezoelectric body 1 can be finer.
It is possible to change the movement of the step by step.

FIG. 12 is a conceptual diagram of driving the piezoelectric actuator according to the second embodiment.

In the piezoelectric actuator shown in FIG. 12, load information from the outside to the piezoelectric actuator in accordance with the lapse of the driving time of the piezoelectric actuator is built in the control unit in advance, and the piezoelectric actuator itself drives via the moving body 4. Shows the case. Due to the design conditions such as the shape of the piezoelectric body 1 itself, the piezoelectric actuator is applied with a voltage to a single electrode in a flat place, and is applied to two electrodes in a place where the angle θ is inclined. It is assumed that a desired moving speed of the piezoelectric actuator can be obtained by applying a voltage.

In FIG. 12A, the piezoelectric actuator has a first electrode portion A15, a first electrode portion B16, and a second electrode portion A17.
And a moving body 4 that moves by being in contact with the piezoelectric body 1. In each electrode portion, a region surrounded by a hatched portion represents a state where a voltage is applied. In the state of FIG. 12A,
This is a case where the piezoelectric actuator moves via the moving body 4 on a horizontal portion A38a which is a flat portion where the load on the piezoelectric actuator is small. In the control unit (shown abbreviated), until time t _1, the first switching section A7 to apply a voltage to the first electrode portion A15, and the instructions of conduction, also the first electrode portion B16 On the other hand, since it is known that the driving characteristics such as a constant rotation speed are maintained without applying a voltage, the first switching unit B8 is instructed to disconnect.

FIG. 12B shows a state where the piezoelectric actuator moves from the horizontal portion A 38 a to the inclined portion 37. The time has passed t ₁ , and the control unit (not shown) determines, from the time t ₁ , the moving unit 4 and the piezo-electric actuator with the inclined portion 37 having the angle θ at which the load increases. Has decided to move. Thereby, in the horizontal portion A38a, when the inclined portion 37 having the inclination angle θ is moved while the voltage is applied to only the first electrode portion A15 and driven, the rotation speed of the moving body 4, that is, In addition, the moving speed of the piezoelectric actuator decreases. Therefore, the control unit (shown abbreviated), at time t _1, a first electrode B16
The second switching unit 8 is instructed to conduct the driving signal so that the driving signal is applied to the second switching unit 8. As a result, the driving force of the piezoelectric actuator is increased by the amount of the voltage applied to the first electrode portion B16, and the inclined portion 37 prevents the driving characteristics such as the number of revolutions of the moving body 4 from decreasing, and moves the piezoelectric actuator. It becomes possible.

FIG. 12C shows a state where the piezoelectric actuator moves from the inclined portion 37 to a flat horizontal portion B38b. The time has passed t ₂ , and the control unit (not shown) judges from the time t ₂ ,
It is determined that the piezoelectric actuator moves on the flat horizontal portion B38b where the load amount decreases. Thus, in the inclined portion 37, the voltage was input to both the first electrode portion A15 and the first electrode portion B16, and the piezoelectric actuator was driven. However, only the voltage was input to the first electrode portion A15. Since the rotation characteristics of the piezoelectric actuator, that is, the movement characteristics, can be sufficiently obtained, the control unit (not shown) instructs the first switching unit 7 to turn on the voltage, and the second switching unit 8 A command to cut off the voltage is issued, and the first electrode portion A
A voltage is applied to 15 and no voltage is applied to the first electrode portion B16. Accordingly, the driving force of the piezoelectric actuator is reduced by the amount of no voltage applied to the first electrode portion B16, and the horizontal portion B38b prevents the driving characteristics such as the rotation speed of the moving body 4 from increasing and moves the piezoelectric actuator. Becomes possible.

As described above, according to the second embodiment, as a method of controlling a piezoelectric actuator composed of a piezoelectric body having a plurality of electrodes, a switching unit for switching between conduction and disconnection of a voltage between each electrode and a drive signal generator. Further, by providing a control unit for determining a conduction and disconnection command of the drive signal and providing a conduction and disconnection command to the switching unit, application and disconnection of the drive signal to each electrode unit in the piezoelectric body are provided. Makes it possible to reduce the drive characteristics such as the rotational speed and force of the piezoelectric actuator.
It is possible to vary by an amount corresponding to the amount of the electrodes used for applying and cutting.

By storing the time and the branch at that time in the control unit in advance, the piezoelectric actuator can be controlled in an open loop.

Further, since the switching section can have a simple structure that can be opened and closed, the structure of the piezoelectric actuator can be reduced in size.

Furthermore, since the piezoelectric actuator can be driven in accordance with an external load, the piezoelectric actuator can be efficiently driven, and when combined with a battery or the like, the life of the battery can be extended. Can be achieved.

<< Embodiment 3 >> Regarding Embodiment 3,
This will be described in detail with reference to FIGS.

FIG. 7 is a block diagram showing the configuration of the piezoelectric actuator according to the third embodiment.

The piezoelectric actuator includes a first electrode portion A15
A first polarization part A21 corresponding to the first electrode part A15,
A first electrode portion B16, a piezoelectric body 1 provided with a first polarization portion B22 corresponding to the first electrode portion B16, a vibrating body 1 made of an elastic material 9 bonded to the piezoelectric body 1, and a drive for generating a drive signal Signal generator 5, first electrode unit A15 and drive signal generator 5
Between the first electrode unit B16 and the drive signal generator 5 between the first switching unit 7 for switching the conduction and disconnection of the drive signal flow, and the second switching unit for switching the conduction and disconnection of the drive signal flow between the first electrode unit B16 and the drive signal generator 5. 8, a control unit 11 for conducting and disconnecting commands to the first switching unit 7 and the second switching unit 8, and a moving body 4 that contacts the vibrating body 10 and moves by the movement of the vibrating body 10. Control unit 1
In 1, conduction and disconnection can be controlled independently of each other by the first switching unit 7 and the second switching unit 8.

FIG. 9 is a schematic diagram of the vibrating body of the piezoelectric actuator according to the third embodiment.

The vibrating body of the piezoelectric actuator according to the second embodiment includes an elastic member 9 having four L-shaped portions,
The piezoelectric body 1 is joined to the shape part, and the vibrating body 1
0. Each piezoelectric body 1 is provided with an electrode portion 2, and when a drive signal is input to the electrode portion 2, bending vibration is excited in the L-shaped portion.

FIG. 10 is a configuration diagram of a piezoelectric actuator according to the third embodiment.

The piezoelectric actuator according to the second embodiment includes an elastic member 9 having four L-shaped portions described with reference to FIG. 9 and a vibrating body 10 in which the piezoelectric body 1 is bonded to each L-shaped portion. A support table 32 serving as a fixed end of the vibrating body 10; a moving body 4 which comes into contact with the vibrating body 10 and rotates around a rotating shaft 28 by bending vibration of an L-shaped portion of the vibrating body 10; And a drive signal generator 5 for inputting a drive signal to the piezoelectric body 1 joined to the L-shaped portion of the piezoelectric element 1. A drive signal generator 5 is provided between the drive signal generator 5 and an electrode section (not shown) provided on the piezoelectric body 1. A switching unit 6 for switching between conduction and disconnection, and a control unit (not shown) provided in the switching unit 6 and instructing conduction and disconnection of voltage
Consists of In order to maintain an appropriate contact state between the moving body 4 and the vibrating body 10, the piezoelectric actuator has a pressing unit 26.
However, a configuration is also provided in which a pressing portion 27 that supports the pressing portion 26 is provided.

FIG. 11 is a speed change diagram of the moving body of the piezoelectric actuator according to the third embodiment, and shows a speed change of the moving body 4 of the piezoelectric actuator shown in FIG.

The moving body 4 of the piezoelectric actuator is driven to rotate in contact with the vibrating body 10 having four L-shaped portions. Here, assuming that the speed at which the moving body 4 is driven and rotated per one of the four L-shaped portions due to the bending vibration of the vibrating body 10 is v, the moving body 4 has two L-shaped portions. 2v when driven by
In three places, it is 3v, and in four places, it is 4v.

The conduction and disconnection of the drive signal to each piezoelectric body 1 in the vibrating body 10 is performed by the switching unit 6, and the determination of conduction or disconnection is performed by the control unit (not shown).

FIG. 11A shows a state where the speed of the moving speed of the moving body of the piezoelectric actuator is gradually reduced.

First, at time t _A1 , the voltage is applied to all four L-shaped portions of the vibrating body 10, and the speed at that time is represented by 4v. Thereafter, at time t _A2 , the four L-shaped piezoelectric bodies 1
In order to prevent the voltage from being applied to the three electrode units 2 among the electrode units 2 in FIG. 1, a voltage disconnection command is transmitted from the control unit (not shown) to the switching unit 6 and the times t _{A1 to} t _A2. In, the speed is 4v, but after t _A2 , the speed becomes v, and the speed can be reduced.

FIG. 11B shows a state where the speed is gradually increased among the speed changes of the moving body of the piezoelectric actuator.

First, at time t _B1 , the voltage is applied to one electrode portion 2 of the four L-shaped portions of the vibrating body 10, and the speed at that time is represented by v. Then, at time t _B2 , the control unit (not shown) sends a signal to the switching unit 6 so that voltage is applied to all four electrode units 2 of the four L-shaped piezoelectric bodies 1. On the other hand, a voltage conduction command is transmitted, and at time t _B1
From t _{A2 to} t _B2 the speed is v, but after t _A2 the speed is 4
v and speed can be increased.

As described above, in the third embodiment, as a method of controlling a piezoelectric actuator composed of a vibrating body in which a piezoelectric body having an electrode portion and an elastic material are joined, a voltage is applied between each electrode portion and the drive signal generator. A switching unit for switching between conduction and disconnection of the drive signal; and a control unit for determining a conduction and disconnection command of the drive signal and providing a conduction and disconnection command to the switching unit. It becomes possible to apply and cut a drive signal to the piezoelectric actuator, and it is possible to change drive characteristics such as the number of rotations and force of the piezoelectric actuator by an amount corresponding to the electrodes used for applying and cutting.

Further, by storing in advance a time and a branch at the time in a control unit (not shown), it is possible to control the piezoelectric actuator in an open loop.

Further, since the switching section can have a simple structure that can be opened and closed, the structure of the piezoelectric actuator can be reduced in size.

Further, since the piezoelectric actuator can be driven in response to an external request, the piezoelectric actuator can be efficiently driven, and when combined with a battery or the like, the life of the battery can be extended. Can be achieved.

<< Embodiment 4 >> Regarding Embodiment 4,
This will be described in detail with reference to FIGS.

FIG. 8 is a block diagram showing a configuration of a piezoelectric actuator according to the fourth embodiment.

The piezoelectric actuator has a first electrode portion A15
A first polarization part A21 corresponding to the first electrode part A15,
A first electrode portion B16, a piezoelectric body 1 provided with a first polarization portion B22 corresponding to the first electrode portion B16, a drive signal generator 5 for generating a drive signal, a first electrode portion A15, and a drive signal generator 5, the first switching unit 7 that switches between conduction and disconnection of the drive signal flow, the first electrode unit B16, and the drive signal generator 5
The second switching unit 8 switches between conduction and disconnection of the drive signal, a control unit 11 that performs conduction and disconnection commands to the first switching unit 7 and the second switching unit 8, and the piezoelectric body 1 The moving body 4 that contacts and moves by the movement of the piezoelectric body 1 and the change in speed and acceleration of the moving body 4 are read and converted into a load amount measurement signal,
And a sensor unit 14 for transmitting to the control unit 11. The control unit 11 determines that the load 39 has been applied to the moving body 4 based on the load amount measurement signal based on the change in the speed or acceleration of the moving body 4. The first switching unit 7 and the second switching unit 8, it is possible to instruct the conduction and disconnection of the drive signal independently.

FIG. 13 is a flowchart showing a control process of the piezoelectric actuator according to the fourth embodiment.

In the piezoelectric actuator, the number of electrode portions provided on the piezoelectric body is the number of electrode portions n, of which the number of electrode portions to which voltage is applied is the number of applied electrode portions a, and the number of electrode portions to which no voltage is applied. Is the number of cut electrode parts b.

First, in the initial stage 101 before driving the piezoelectric actuator, the number of applied electrode parts = 0 and the number of cut electrode parts = n (the number of all electrodes).

Next, in the initial drive stage 102, the drive is started. As the first drive, the state of the electrode units at this time is assumed to be the number of applied electrode units = a and the number of cut electrode units = b.

Next, the state of the rotational speed and acceleration of the moving body of the piezoelectric actuator is measured by the sensor unit, and the control unit obtains a load amount measurement signal. from the signal to obtain the initial state of the moving body of the piezoelectric actuator, to determine an initial load to the mobile and F _0. Then, the initial load F ₀ as the current load, and assigned to the current load Fn.

Next, the state of the rotation speed and acceleration of the moving body of the piezoelectric actuator is measured by the sensor unit, and the control unit obtains the load amount measurement signal.
As 4, the control unit compares the change in the load amount of the piezoelectric actuator with the current load amount Fn from the load measurement signal, and obtains the change from the load amount. Thereby, it is determined how many the number of applied electrode parts and the number of cut electrode parts are changed, and the amount is set as the number i of changed electrodes.

Further, in the load comparison stage 105, the load amount F is determined from the load measurement signal, and the load amount F and the current load amount F are calculated.
Branching is performed in three ways by comparison with n.

First, in the first comparative expression 106a,
When the load F is larger than the current load Fn. The number a of applied electrode parts is increased by i, and the number b of cut electrode parts is reduced by i.
In the second comparative expression 106b, the load F is equal to the current load Fn. Number of applied electrode parts a, number of cut electrode parts b
Is not changed. In the third comparative expression 106c, the load F is smaller than the current load Fn. The number a of applied electrode parts is decreased by i, and the number b of cut electrode parts is increased by i. Branching into the above three ways, instruction stage 1
In step 07, the control unit instructs the switching unit to turn on and off the voltage, so that the driving characteristics such as the driving speed of the piezoelectric actuator can be stably maintained in response to the load on the piezoelectric actuator. .

Thereafter, in the current load acquisition stage 108, the control unit determines the current load amount as Fn based on the load amount measurement signal from the sensor unit.

Thereafter, in the drive continuation judging step 109, an input of whether to continue or stop the drive is waited. If the drive is to be continued, the current load Fn is fed back, the load measurement signal is measured, and the number of changed electrodes is measured. The process proceeds to the step 104 for determining the number of applied electrodes determined by i. When stopping, the process proceeds to the stop step 110, where the number of applied electrodes is set to 0 and the number of cut electrodes is set to n.

By taking the above processes into account, it is possible to vary the driving of the piezoelectric actuator according to the load amount, and it is possible to stably drive the piezoelectric actuator.

FIG. 14 is a configuration diagram of a piezoelectric actuator according to the fourth embodiment.

The piezoelectric actuator has a second electrode portion A17.
, A second electrode portion B18, a first electrode portion A (not shown), and a first electrode portion B (not shown), and a bending layer 30 for exciting bending vibration and a stretching layer 29 for exciting stretching vibration (not shown). (Abbreviated)
A driving signal generator 5 for inputting a driving signal to the second electrode portion A17 and the second electrode portion B18;
A first switching unit A7 that is between the drive signal generator 5 and the second electrode unit A17 and switches between conduction and disconnection of the drive signal; and a drive unit that is between the drive signal generator 5 and the second electrode unit B18, A second switching portion B8 for switching between conduction and disconnection of a signal, and a contact with the piezoelectric body 1, rotating about the rotation shaft 28, and a first gear 34 are provided on one surface, and are further marked so as to prevent light reflection. A moving body 4 having a marking section 36 and a sensor section which measures the passage of the marking section 36 which rotates about the rotation axis 28 by the rotation of the moving body 4 by the presence or absence of light reflection, and which is fixed and does not move. 14, a control unit 11 that receives a measurement signal from the sensor unit 14, and instructs the first switching unit 7 and the second switching unit 8 to command conduction and disconnection of a drive signal, and the mobile unit 4.
And a second gear 35 which is driven by the power of the first gear 34 as required.

In the initial state, the first switching section 7 conducts the drive signal to the second electrode section A17 provided on the piezoelectric body 1, and the second switching section 8 connects to the second electrode section B18. The driving signal is cut off, and the piezoelectric body 1 draws an elliptical motion by combining bending vibration and expansion / contraction vibration, and makes the moving body 4 rotate by contact with the moving body 4. Moving object 4
With the rotation of, the marking unit 36 is also performing a rotational movement at the same time, and the rotation speed state of the moving body 4 at this time is measured by the sensor unit 14 and transmitted to the control unit 11 as a load amount measurement signal.

Then, as required by the power, the second gear 3
When the gear 5 meshes with the first gear 34, the rotation speed of the moving body 4 is reduced as compared to before the second gear 35 meshes with the first gear 34, and the marking section 36 is rotated with the rotation of the moving body 4. From the sensor unit 14 that was measuring the rotation of
The load amount measurement signal is transmitted to the control unit 11, and the control unit 11
Then, it is determined from the change in the load amount measurement signal that the load amount on the moving body 4 has increased, and the second switching unit 8 is instructed to conduct the drive signal. The second switching unit 8 receives a drive signal conduction command from the control unit 11 and switches from a cut-off state of the drive signal to a conduction of the drive signal to the second electrode unit B18. Thereby, the amount of the drive signal applied to the piezoelectric body 1 increases, and the vibration of the piezoelectric body 1 increases. Thereby,
The driving force received by the moving body 4 in contact with the piezoelectric body 1 increases,
The drive characteristics can be increased in response to the reduction of the drive characteristics due to the load applied to the moving body 4.

Conversely, when the second gear 35 separates from the first gear 34 as necessary, the rotation speed of the moving body 4 increases as compared with the case where the second gear 35 meshes with the first gear 34. Then, with the rotation of the moving body 4, a load amount measurement signal from the sensor unit 14 that has measured the rotation of the marking unit 36 is transmitted to the control unit 11, and the control unit 11
From the change in the load amount measurement signal, it is determined that the load amount on the moving body 4 has been reduced, and the second switching unit 8 is instructed to cut off the drive signal. The second switching unit 8 receives a drive signal disconnection command from the control unit 11 and changes the drive signal conduction state to
The second electrode portion B18 is switched to cut off the drive signal. Thereby, the amount of the drive signal applied to the piezoelectric body 1 decreases, and the vibration of the piezoelectric body 1 decreases. As a result, the driving force received by the moving body 4 that comes into contact with the piezoelectric body 1 is reduced, and the driving characteristics can be reduced in response to the reduced load from the moving body 4.

As a result, the driving characteristics of the moving body 4 can be increased and decreased according to the load on the moving body 4, and the moving body 4 can be driven stably. Further, when the load is required, the driving force is increased, and when the load is not required, the driving force is reduced, so that the input electric energy can be used efficiently.

As described above, in the fourth embodiment, the control unit determines the amount of load on the moving body from changes in the rotation speed and acceleration of the moving body, and conducts the drive signal to the electrode unit provided on the piezoelectric body. The disconnection is instructed to the switching unit, and the switching unit conducts and disconnects the drive signal, so that the driving characteristics of the piezoelectric actuator can be changed according to the load amount. As a result, not only can the driving state such as the rotation speed of the moving body be stabilized, but also the input energy can be varied according to the load on the moving body, thus realizing efficient use of energy. it can.

[0119]

According to the present invention, the voltage application to the electrodes provided on the piezoelectric actuator is performed by using the switching unit in accordance with the load condition on the moving body. By providing a control unit that issues instructions and combining it with a sensor unit that measures the load status of a moving object, the piezoelectric actuator can be driven stably with a simple circuit configuration, and the size of the piezoelectric actuator can be reduced. It is. In addition, since the energy of the drive signal is varied according to the load, it is possible to use electric energy efficiently.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a driving principle of a piezoelectric actuator according to a first embodiment.

FIG. 2 is a diagram showing a configuration of a rectangular piezoelectric actuator.

FIG. 3 is a diagram illustrating a driving principle of a rectangular piezoelectric actuator.

FIG. 4 is an assembly view of the micro piezoelectric actuator.

FIG. 5 is an explanatory diagram showing the operation principle of the micro piezoelectric motor.

FIG. 6 is a block diagram illustrating a configuration of a piezoelectric actuator according to a second embodiment.

FIG. 7 is a block diagram showing a configuration of a piezoelectric actuator according to a third embodiment.

FIG. 8 is a block diagram showing a configuration of a piezoelectric actuator according to a fourth embodiment.

FIG. 9 is a schematic diagram of a vibrating body of the piezoelectric actuator according to the third embodiment.

FIG. 10 is a configuration diagram of a piezoelectric actuator according to a third embodiment.

FIG. 11 is a diagram showing a moving speed change of the moving body of the piezoelectric actuator according to the third embodiment.

FIG. 12 is a conceptual diagram of driving the piezoelectric actuator according to the second embodiment.

FIG. 13 is a flowchart showing a control process of the piezoelectric actuator according to the fourth embodiment.

FIG. 14 is a configuration diagram of a piezoelectric actuator according to a fourth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric body 2 Electrode part 3 Polarization part 4 Moving body 5 Drive signal generator 6 Switching part 7 First switching part 8 Second switching part 9 Elastic material 10 Vibration body 11 Control part 12 Cutting electrode part 13 Application electrode part 14 Sensor part DESCRIPTION OF SYMBOLS 15 First electrode part A 16 First electrode part B 17 Second electrode part A 18 Second electrode part B 19 Third electrode part 20 GND electrode part 21 First polarized part A 22 First polarized part B 23 Second polarized part A 24 Second polarized portion B 25 Third polarized portion 26 Pressurizing portion 27 Pressing portion 28 Rotating shaft 29 Stretchable layer 30 Bend layer 31 GND layer 32 Support table 33 Bend displacement section 34 First gear 35 Second gear 36 Marking section 37 Inclined portion 38a Horizontal portion A 38b Horizontal portion B 39 Load 101 Initial stage 102 Initial drive stage 103 Initial load determination stage 104 Number of applied electrodes determination stage 105 Load comparison stage 106a, b, c Comparison formula 107 Command stage 106 Current load acquisition stage 109 Driving continuation determination stage 110 Stop stage

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kazuo Tani 1-8-1, Nakase, Mihama-ku, Chiba-shi, Chiba Prefecture Inside SII IR D Center (72) Inventor Yoko Shinohara 1 Nakase, Mihama-ku, Chiba-shi, Chiba 8th Street FII Term in SII RDI Center (Reference) 5H680 AA06 BB02 CC02 DD15 DD23 DD35 DD39 EE12

Claims (12)

[Claims] 1. A piezoelectric body having at least two electrode units and a polarization unit at a position corresponding to the at least two electrode units, and at least one piezoelectric body that moves when a voltage is applied to the at least two electrode units. A moving body that is driven in contact with the piezoelectric body; and a piezoelectric actuator that includes a drive signal generator that applies a voltage to the at least two electrode units. A piezoelectric actuator, comprising: a switching unit for switching between the at least two electrode units and the drive signal generator. 2. At least two electrode parts, at least one piezoelectric body having a polarization part at a position corresponding to the at least two electrode parts, and moving by applying a voltage to the at least two electrode parts; A vibrating body in which the piezoelectric body and an elastic material are joined; a moving body that is driven in contact with the vibrating body; and a piezoelectric actuator including a drive signal generator that applies a voltage to the at least two electrode units. A piezoelectric actuator, comprising: a switching unit that switches between disconnection and conduction of a voltage applied to two electrode units, between the at least two electrode units and the drive signal generator. 3. The piezoelectric actuator according to claim 1, wherein the switching unit includes a control unit that instructs switching of voltage disconnection and conduction. 4. The piezoelectric actuator according to claim 1, wherein a voltage is applied to at least two of the electrode units, and the voltage from the control unit is changed from a state in which the moving body is driven. In accordance with a disconnection command, the switching unit disconnects the voltage to at least one of the electrode units to which a voltage is applied, and the disconnected electrode unit becomes a cutting electrode unit, and the cutting electrode unit is disconnected A moving force of the moving body is reduced by an amount corresponding to the applied voltage amount. 5. The piezoelectric actuator according to claim 1, wherein at least one of the electrodes is disconnected from a state in which at least one of the electrodes is disconnected, and a voltage conduction command is issued from the control unit. The switching unit conducts a voltage to at least one of the electrode units whose voltage is cut off, and the electrode unit to which the voltage is applied becomes an application electrode unit, and a voltage amount applied to the application electrode unit. A piezoelectric actuator, wherein the moving force of the moving body is increased by a considerable amount. 6. The piezoelectric actuator according to claim 1, further comprising a sensor unit for measuring a driving state of the piezoelectric actuator. 7. The piezoelectric actuator according to claim 6, wherein the sensor unit measures a speed of the moving body and transmits the speed to the control unit as a measurement signal. 8. The piezoelectric actuator according to claim 6, wherein the sensor unit measures an acceleration of the moving body and transmits the acceleration to the control unit as a measurement signal. 9. The method for controlling the operation of a piezoelectric actuator according to claim 1, wherein the sensor unit detects a speed of the moving body; and the sensor unit. Transmitting the speed of the moving body to the control unit as a measurement signal, the control unit determines a change in the speed of the moving body from the measurement signal, and reduces the load on the moving body from outside. Responsively, instructing the switching unit to disconnect the voltage, the method for controlling a piezoelectric actuator. 10. The method of controlling the operation of a piezoelectric actuator according to claim 1, wherein the sensor section detects a speed of the moving body; and the sensor section. Transmitting the speed of the moving object to the control unit as a measurement signal, the control unit determines a change in the speed of the moving object from the measurement signal, and increases the external load on the moving object. Responsively, instructing the switching unit to conduct voltage, and controlling the piezoelectric actuator. 11. The method for controlling the operation of a piezoelectric actuator according to claim 1, wherein the sensor unit detects an acceleration of the moving body; and the sensor unit. Transmitting the acceleration of the moving object to the control unit as a measurement signal, the control unit determines a change in the acceleration of the moving object from the measurement signal, and reduces the load on the moving object from outside. Responsively, instructing the switching unit to disconnect the voltage, the method for controlling a piezoelectric actuator. 12. The method for controlling the operation of a piezoelectric actuator according to claim 1, wherein the sensor section detects an acceleration of the moving body; and the sensor section. Transmitting the acceleration of the moving object to the control unit as a measurement signal, the control unit determines a change in the acceleration of the moving object from the measurement signal, and increases the external load on the moving object. Responsively, instructing the switching unit to conduct voltage, and controlling the piezoelectric actuator.