JP2000208826A - Piezoelectric element actuator driving device, driving method of camera and piezoelectric element actuator using the device, focussing method of camera using the device, and recording medium readable by computer and recorded with program for executing focussing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the driving speed of a piezoelectric element actuator and to shorten an overall treating time on a drive of the actuator including the time of a polarization treatment. SOLUTION: A relation acquiring part 15 makes a piezoelectric element 8 charge by an application of a charging pulse S1 before a real drive of the element 8 after a power supply is turned on, acquires the relation between a pulse number of charging and a charged voltage which is shown by a charged voltage detecting signal S2, and stores the relation between the pulse number for charging and the charged voltage in a voltage/pulse conversion table 13. A control part 11 finds the quantity of a voltage equivalent to a displacement quantity input 21 of the element 8 from a previously set displacement quantity/voltage conversion table 14 at the time of a real drive of the element 8, converts the pulse number for charging to correspond to the charged voltage on the basis of the relation stored in the table 13, and applies pulses for charging of the pulse number for charging to a base of a switching transistor 2 to perform a drive of the element 8 while the element 8 is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving apparatus for a piezoelectric element actuator, an apparatus using the same, a driving method for the piezoelectric element actuator, a focusing method for a camera using the driving apparatus for the piezoelectric element actuator, and a computer using the same. The present invention relates to a computer-readable recording medium storing a program to be executed by a computer.

[0002]

2. Description of the Related Art Conventionally, a piezoelectric element actuator formed by laminating piezoelectric elements has a small displacement, but has a high response speed and a large pressure. Therefore, it is used as a precision control actuator particularly for a minute displacement. For example, various types of precision positioning in semiconductor device manufacturing equipment, micromanipulators for cell operation, control of positions of mirrors and lenses in optical systems, inclination or focal length, error correction in machine tools, print heads for printers of OA equipment, etc. Piezoelectric actuators are used in various fields.

For example, Japanese Patent Application Laid-Open No. Hei 8-272247 discloses that a pulse waveform having a gentle fall and a steep rise or a pulse waveform having a gentle rise and a steep fall is applied to a piezoelectric element having an inertial body. A precision positioning method is described in which precise positioning can be easily performed by applying a voltage to drive a moving stage without handling two control systems of coarse movement and fine movement.

[0004] When a strain or a stress is applied to a piezoelectric element, an electric charge is induced, and when a voltage is applied, a strain or a stress is generated. A piezoelectric ceramic element, which is a piezoelectric element, obtains piezoelectricity by firing a powder to form a polycrystal, applying a DC voltage to the polycrystal, and causing remanent polarization.

Further, it is necessary to perform a polarization process on the piezoelectric element. The polarization treatment is to gradually apply a voltage to be used, for example, 120 V, to the piezoelectric element for several seconds, and when a certain voltage is reached, hold this state for a predetermined time, and then discharge to align the directions of the polarizers. Processing.

When a device using this piezoelectric element is manufactured, polarization processing is always performed, and thereafter, the piezoelectric element is incorporated into the device. Then, the polarization is destroyed by the passage of time and temperature rise, and if the piezoelectric element is not used for a long time, the function as the piezoelectric element will not be exhibited,
Polarization processing is performed at the time of device diagnosis, power-on, at regular intervals, or at the time of maintenance, to prevent the functional degradation of the device due to polarization destruction, and to always drive the normally functioning piezoelectric element actuator. (JP-A-5-167124)
Reference).

[0007]

However, when the drive control of the piezoelectric element actuator is performed, the voltage applied to the piezoelectric element is detected and the displacement amount of the piezoelectric element actuator is sequentially controlled. It takes a long time to reach the voltage of the piezoelectric element, and despite the high-speed response of the piezoelectric element, the driving speed of the piezoelectric element actuator is reduced, and the high-speed response of the piezoelectric element actuator cannot be fully utilized. There was a problem.

As described above, the piezoelectric element needs to be subjected to the polarization processing, and the polarization processing itself takes a long time. However, if the polarization processing is performed every time the power is turned on, the actual operation of the piezoelectric element actuator is performed. There is a problem that it takes more time to drive, and the overall processing efficiency of the piezoelectric element actuator is reduced.

The present invention has been made in view of the above, and it is possible to significantly improve the driving speed of a piezoelectric element actuator, and to reduce the overall processing time for driving the piezoelectric element actuator including polarization processing. Driving device for piezoelectric element actuator which can be shortened, device using the same, driving method for piezoelectric element actuator, focusing method for camera using driving device for piezoelectric element actuator, and recording program for causing computer to execute the method It is an object of the present invention to provide a computer-readable recording medium.

[0010]

According to a first aspect of the present invention, there is provided a driving apparatus for a piezoelectric element actuator, comprising the steps of: applying a charging voltage corresponding to a charging pulse to a piezoelectric element in the piezoelectric element actuator; In the driving device of the piezoelectric element actuator, which controls the amount of displacement of the piezoelectric element by applying the driving, and controls the driving of the piezoelectric element actuator,
Charging means for energizing the piezoelectric element by applying the charging pulse to charge the piezoelectric element, and energizing the piezoelectric element by applying the discharging pulse to discharge the piezoelectric element. Discharging means for performing, detecting means for detecting the charging voltage of the piezoelectric element,
After the power is turned on and before the piezoelectric element is actually driven, the piezoelectric element is charged by applying the charging pulse through the charging means, and the number of charging pulses at the time of charging and the charging voltage detected by the detecting means. And a conversion table that defines a relationship between the number of charging pulses and the charging voltage obtained by the obtaining unit, and a displacement amount of the piezoelectric element when the piezoelectric element is actually driven. The number of charging pulses corresponding to the amount of voltage corresponding to is calculated with reference to the conversion table, and the charging pulse of the calculated number of charging pulses is applied via the charging means to control the driving of the piezoelectric element. And a drive control means for performing the following.

According to a second aspect of the present invention, in the driving device for a piezoelectric element actuator according to the first aspect of the present invention, when the obtaining means obtains the relationship between the number of charging pulses and a charging voltage, It is characterized in that charging is performed up to the maximum rated voltage and polarization processing is also performed at the time of acquisition.

According to a third aspect of the present invention, there is provided a driving device for a piezoelectric element actuator according to the first or second aspect of the invention.
The acquiring unit, when acquiring the relationship between the number of charging pulses and the charging voltage, causes the voltage detecting unit to detect the charging voltage for each predetermined number of pulses, and determines the relationship between the number of charging pulses and the charging voltage. It is characterized by acquiring a relationship.

According to a fourth aspect of the present invention, there is provided a driving device for a piezoelectric element actuator according to the first or second aspect of the invention.
The acquiring unit acquires the relationship between the number of charging pulses and the charging voltage by causing the voltage detecting unit to detect the charging voltage for each pulse when acquiring the relationship between the number of charging pulses and the charging voltage. It is characterized by doing.

According to a fifth aspect of the present invention, in the driving device for a piezoelectric element actuator according to the first to fourth aspects of the present invention, the acquiring unit acquires the relationship between the charging pulse number and the charging voltage when acquiring the relationship between the charging pulse number and the charging voltage. Change the pulse frequency of the
A pulse frequency that can be charged at the highest speed to a predetermined voltage is acquired, and the drive control unit performs drive control of the piezoelectric element based on the number of charging pulses having the pulse frequency acquired by the acquisition unit. Features.

According to a sixth aspect of the present invention, in the driving apparatus for a piezoelectric element actuator according to the first to fifth aspects, it is monitored whether a power supply voltage of a power supply for charging the piezoelectric element is within a predetermined allowable range. When the power supply voltage is not within the predetermined allowable range, the relationship between the number of charging pulses and the charging voltage is reacquired, and the relationship between the number of charging pulses and the charging voltage stored in the conversion table is updated. And a power supply monitoring means for controlling the power supply.

According to a seventh aspect of the present invention, in the driving device for a piezoelectric element actuator according to any one of the first to sixth aspects, the voltage immediately before the discharge of the piezoelectric element is measured, and the number of charging pulses stored in the conversion table is measured. Based on the relationship between the measured voltage and the charging voltage, it is detected whether or not the difference between the measured voltage and the charging voltage corresponding to the number of charging pulses during the measurement is within a predetermined range, and is not within the predetermined range. In this case, the apparatus further comprises a relation monitoring unit for reacquiring the relation between the number of charging pulses and the charging voltage and updating the relation between the number of charging pulses and the charging voltage stored in the conversion table. And

In a driving apparatus for a piezoelectric element actuator according to an eighth aspect of the present invention, in the invention according to any one of the first to seventh aspects, when discharging the piezoelectric element, the obtaining means charges the piezoelectric element to a maximum rated voltage. After that, discharge is performed.

According to a ninth aspect of the present invention, there is provided a camera using the driving device for a piezoelectric element actuator according to any one of the first to eighth aspects.

According to a tenth aspect of the present invention, there is provided a camera for driving a focusing mechanism using a piezoelectric element, and energizing the piezoelectric element by applying a charging pulse to charge the piezoelectric element. A charging unit, a discharging unit that causes a current to flow through the piezoelectric element by applying a discharge pulse to discharge the piezoelectric element, and a high-frequency component detecting unit that detects a high-frequency component of an image signal output from the imaging element. At the time of pre-scanning when performing the focusing process by driving the driving means, at the time of the pre-scan, at the time of the pre-scan, the number of pulses for charging when the high frequency component detected by the high frequency component detection means is the maximum. After discharging the charged piezoelectric element, the number of charging pulses acquired by the pulse number acquiring means is applied to the piezoelectric element by charging pulses to achieve focusing. Characterized by comprising a drive control means for causing the actual driving of the fit.

According to the eleventh aspect of the invention, there is provided a driving method of a piezoelectric element actuator, wherein a charging voltage corresponding to a charging pulse and a discharging pulse is applied to the piezoelectric element in the piezoelectric element actuator to reduce the displacement of the piezoelectric element. A driving step of controlling the driving of the piezoelectric element actuator by controlling the driving amount of the piezoelectric element actuator. An obtaining step of obtaining the relationship between the charging voltage of the piezoelectric element and the number of charging pulses; and obtaining the charging voltage for the input displacement amount based on the relationship held in the holding step. The number of pulses is obtained from the relationship obtained in the obtaining step, and the actual driving of the piezoelectric element is controlled by applying the charging pulse of the obtained number of charging pulses. Characterized in that it contains a control process.

According to a twelfth aspect of the present invention, in the driving method of the piezoelectric element actuator according to the eleventh aspect of the present invention, the obtaining step includes charging up to a maximum rated voltage of the piezoelectric element and charging voltage and charging pulse of the piezoelectric element. It is characterized in that a relationship with a number is obtained, and a polarization process is also performed.

According to a thirteenth aspect of the present invention, in the driving method of the piezoelectric element actuator according to the eleventh or twelfth aspect,
The obtaining step is characterized in that a charging voltage applied to the piezoelectric element is detected for each predetermined number of pulses, and a relationship between the charging voltage of the piezoelectric element and the number of charging pulses is obtained.

According to a fourteenth aspect of the present invention, in the driving method of the piezoelectric element actuator according to the eleventh or twelfth aspect,
The acquisition step is characterized in that a charging voltage applied to the piezoelectric element is detected for each pulse, and a relationship between the charging voltage of the piezoelectric element and the number of charging pulses is acquired.

According to a fifteenth aspect of the present invention, in the driving method of the piezoelectric element actuator according to the eleventh to fourteenth aspects, the obtaining step comprises changing a pulse frequency of the piezoelectric element to charge the piezoelectric element to a predetermined voltage at the highest speed. And a relationship obtaining step of obtaining a relationship between the charging voltage of the piezoelectric element and the number of charging pulses at the pulse frequency determined by the frequency determining step.

According to a sixteenth aspect of the present invention, in the driving method of the piezoelectric element actuator according to the eleventh to fifteenth aspects, the power supply for monitoring whether or not a power supply voltage of a power supply for charging the piezoelectric element is within a predetermined allowable range. A voltage monitoring step; and a reacquisition step of reacquiring a relationship between the number of charging pulses and the charging voltage when the power supply voltage is not within a predetermined allowable range by monitoring the power supply voltage monitoring step. And

According to a seventeenth aspect of the present invention, in the driving method of the piezoelectric element actuator according to the eleventh to sixteenth aspects, the voltage of the piezoelectric element immediately before discharging is measured, and the number of charging pulses and the charging obtained in the obtaining step are measured. A relationship monitoring step of detecting whether a difference between the measured voltage and a charging voltage corresponding to the number of charging pulses at the time of the measurement is within a predetermined range, based on the relationship with the voltage, The method may further include a relation reacquiring step of reacquiring the relation between the number of charging pulses and the charging voltage when the difference is not within the predetermined range by monitoring the step.

The driving method of a piezoelectric element actuator according to the present invention is characterized in that, in the method of the present invention, the obtaining step includes discharging the piezoelectric element after charging the piezoelectric element to a maximum rated voltage. .

According to a nineteenth aspect of the present invention, in a camera focusing method using a driving device for a piezoelectric element actuator, a charging pulse is applied during prescanning before the piezoelectric element actuator for driving a focusing mechanism is actually driven. Obtaining a relationship between the number of charging pulses at this time and a high-frequency component value of an image signal of a subject imaged via a focusing mechanism; and Based on the relationship between the number of charging pulses and the high-frequency component value obtained by the process, the number of pulses determining step of determining the number of charging pulses when the high-frequency component value is maximum, and After discharging the piezoelectric element,
A focusing step of applying a charging pulse of the charging pulse number determined in the pulse number determining step to the piezoelectric element to perform a focusing process.

A recording medium according to a twentieth aspect of the present invention is characterized by recording a program for causing a computer to execute the method according to any one of the eleventh to nineteenth aspects.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a driving device for a piezoelectric element actuator and a camera using the same according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a circuit diagram showing a driving device of a piezoelectric element actuator according to the first to fourth embodiments of the present invention. In FIG. 1, the driving device for the piezoelectric element actuator includes a control unit 11, a driving circuit 20, and a piezoelectric element 8.

The drive circuit 20 has a DC power supply 1, and a primary coil of a step-up transformer 3 and a switching transistor 2 connected in series are connected in parallel to the power supply 1. The diode 4 and the resistors 6 and 7 connected in series are connected in parallel to the secondary coil of the step-up transformer 3. This diode 4 has a forward charging direction.

Further, the resistors 6 and 7 connected in series include:
The diode 5 and the piezoelectric element 8 connected in series are connected in parallel. The charging direction of this diode 5 is also the forward direction.
Furthermore, a resistor 9 and a switching transistor 10 connected in series are connected in parallel to the piezoelectric element 8. Here, the negative side of the power supply 1, the switching transistors 2, 10
, One end of the secondary coil of the step-up transformer 3, one end of the resistor 7, and one end of the piezoelectric element 8 are commonly grounded.

When charging the piezoelectric element 8, the charging pulse S1 from the control unit 11 is applied to the base of the switching transistor 2, and the switching transistor 2 is turned on during the period in which the charging pulse S1 is applied. State. Therefore, when the switching transistor 2 is conducting, the energy from the power supply 1 is applied to the primary coil of the step-up transformer 3 and a boosted voltage is generated in the secondary coil. Using the voltage generated in the secondary coil as a voltage source, energy is applied to the piezoelectric element 8 functioning as a capacitor via the diode 4 and the diode 5 and to the resistors 6 and 7 via the diode 4. During this charging, the switching transistor 10 is off. The voltage between the resistor 6 and the resistor 7 and the ground, that is, the voltage applied to the resistor 7 is detected by the control unit 11 as a voltage detection signal S2. This detection voltage is obtained by connecting a resistor 6 and a resistor 7 connected in series.
And the voltage applied to the piezoelectric element 8 is detected.

When the charging voltage applied to the piezoelectric element 8 is discharged, the switching transistor 2 is turned off, and a discharge pulse S3 is applied to the base of the switching transistor 10 to be turned on. As a result, the electric charge stored in the piezoelectric element 8 is discharged via the resistor 9 and the switching transistor 10.

The charging and discharging processes are performed under the control of the control unit 11. That is, the control unit 11
Applies a charging pulse S1 to the base of the switching transistor 2 when charging the piezoelectric element 8,
The charging voltage applied to the piezoelectric element 8 is controlled according to the number of the applied charging pulses S1. To discharge the piezoelectric element 8, a discharge pulse S3 is applied to the base of the switching transistor 10, and the switching transistor 10 is turned on to discharge the electric charge accumulated in the piezoelectric element 8.

The control unit 11 includes a memory 12 and a relation acquisition unit 1
5, a relation monitoring unit 16 and a power supply monitoring unit 17.

The memory 12 stores various programs and data for the control of the control unit 11, and has at least a voltage / pulse conversion table 13 and a displacement / voltage conversion table 14.

The voltage / pulse conversion table 13 is a conversion table that stores a conversion relationship between the charging voltage applied to the piezoelectric element 8 and the number of charging pulses S1 applied to the switching transistor 2. It is acquired by initial processing or re-acquisition processing by the relation monitoring unit 16 or the power supply monitoring unit 17 and is initially stored or updated. This processing will be described later.

The displacement / voltage conversion table 14 is a conversion table for storing a conversion relationship between the displacement of the piezoelectric element 8 and a voltage for generating the displacement. When the piezoelectric element actuator is mounted, Is written in advance. The conversion relationship stored in the displacement / voltage conversion table 14 is used to correct the variation between the voltage of the piezoelectric element 8 itself and the amount of displacement. Is hardly changed even after the operation, the data is stored semi-permanently after assembling the unit of the piezoelectric element actuator or after assembling the product.

The relation monitoring unit 16 monitors whether or not the contents of the voltage / pulse conversion table 13 obtained by the initial processing by the relation acquisition unit 15 have changed due to environmental changes such as temperature changes. When an error exceeding a predetermined range occurs, the contents of the voltage / pulse conversion table 13 are reacquired, and the processing will be described later.

The power supply monitoring unit 17 detects whether or not the power supply voltage detected by the power supply voltage detection unit 1a connected in parallel to the power supply 1 is within an allowable range by using a power supply voltage detection signal S4. Is exceeded, the contents of the voltage / pulse conversion table 13 are reacquired, and the processing will be described later. Note that the allowable range of the power supply voltage refers to a range of the power supply voltage in which the drive circuit 20 operates normally.

The power supply 1 is a DC power supply of several volts, and is boosted up to one hundred and several tens of volts by the step-up transformer 3 when the charging pulse S1 is applied.

Next, referring to the flowchart of FIG.
A drive control processing procedure including an initial processing of the driving device of the piezoelectric element actuator according to the first embodiment of the present invention will be described.

In FIG. 2, the control section 11 first determines whether or not the power for driving the piezoelectric element actuator has been turned on (step S10). When the power is turned on (step S10, YES), an initial process (step S10)
The routine of 100) is executed by the relation acquisition unit 15. That is, first, the relationship acquisition unit 15 applies one charging pulse S1 to the base of the switching transistor 2 (Step S11). Further, the number n of the applied charging pulses S1 is counted (step S12).

Thereafter, the number n of the charging pulses S1 becomes a predetermined number k.
Is determined (step S13), and if it is not an integral multiple of the predetermined number k (step S13, NO), the process proceeds to step S11 to further apply one charging pulse S1. . On the other hand, if it is an integral multiple of the predetermined number k (step S13, YES), the voltage of the resistor 7 corresponding to the charging voltage of the piezoelectric element 8 is detected (step S1).
4) The relationship between the current number n of charging pulses S1 and the detected voltage is stored (step S15).

Thereafter, it is determined whether or not the detected voltage has reached the maximum rated voltage (step S16). If the detected voltage has not reached the maximum rated voltage (step S16, NO), the flow shifts to step S11 to proceed to the next step. One charging pulse S1 is applied to the switching transistor 2, and the above-described processing is repeated. On the other hand, when the detected voltage has reached the maximum rated voltage (step S16, YES), the relationship acquisition unit 15 performs the voltage / pulse conversion table based on the relationship between the number of charging pulses S1 stored so far and the detected voltage. 13 is generated (step S17).

Thereafter, a discharge pulse S3 is applied to the base of the switching transistor 10 to discharge the electric charge accumulated in the piezoelectric element 8 (Step S18).

The voltage / pulse conversion table 13 is generated by the initial processing of steps S11 to S18 (step S100). When the maximum rated voltage is determined in step S16, the predetermined number k is not considered, but the maximum rated voltage may be set lower in consideration of the predetermined number k. In general, the maximum rated voltage is
Since there is an allowable voltage range, if the predetermined number k is within the allowable voltage range, there is no need to particularly consider it.

Such an initial processing (step S100)
Is completed, the control unit 11 determines whether or not there is an instruction to actually drive the piezoelectric element actuator (step S2).
0), when there is an instruction to actually drive (step S2)
(0, YES), the number of charging pulses S1 corresponding to the displacement input 21 is obtained, and the number of charging pulses S1 is applied to the base of the switching transistor 2 at a predetermined pulse frequency (step S21), and the piezoelectric element is turned on. The actuator is actually driven. The number of the charging pulses S1 is obtained by first converting the voltage corresponding to the displacement input 21 into the displacement / voltage conversion table 14.
, And the number of charging pulses corresponding to the obtained voltage is obtained from the voltage / pulse conversion table 13.

Thereafter, the control unit 11 determines whether or not there is the next actual drive, that is, whether or not there is a displacement input 21 (step S).
22) If there is a displacement amount input 21 (step S22,
(YES), the discharge process is performed by applying the discharge pulse S3 to the base of the switching transistor 10 (step S24), and then the process proceeds to step S21, where the number of the charge pulses S1 corresponding to the displacement input 21 is calculated. The process of applying the voltage to the base of the switching transistor 2 to actually drive the piezoelectric element is repeated. On the other hand, when there is no displacement amount input 21 (step S22, NO), the same discharge process as step S24 is performed (step S23), and this process ends.

FIG. 3 is a diagram showing the relationship between the number of charging pulses and the charging voltage acquired by the relationship acquiring section 15 of the driving device for the piezoelectric element actuator according to the first embodiment of the present invention. 3 shows the relationship between the number of charging pulses and the charging voltage obtained by setting the predetermined number k to 50. In the relationship shown in FIG. 3, the rate of increase of the charging voltage decreases as the number of charging pulses increases.

As shown in FIG. 3, a voltage / pulse conversion table 13 is generated by performing, for example, an approximation process as shown in FIG. Is done. That is, FIG. 4 is a diagram showing an example of the contents stored in the voltage / pulse conversion table 13 of the driving device of the piezoelectric element actuator according to the first embodiment of the present invention. An approximate relationship of connecting each point of the charging voltage with respect to the number of charging pulses thus obtained by a straight line is stored as a voltage / pulse conversion table 13. In this case, the voltage / pulse conversion table 13 can be generated quickly.

FIG. 5 is a diagram showing another example of the contents stored in the voltage / pulse conversion table 13 of the driving device of the piezoelectric element actuator according to the first embodiment of the present invention. The conversion relationship is realized by a regression curve approximated by performing a regression calculation of points at predetermined k units of the charging voltage with respect to the number of charging pulses obtained in FIG. In this case, it is possible to statistically reduce the error between points for each predetermined number k units in comparison with FIG.

FIGS. 6A and 6B are perspective views showing an example of the configuration of the piezoelectric element actuator according to the first embodiment of the present invention. FIG. 6A is an exploded view, and FIG. Each is shown.

In FIG. 6, reference numeral 8 denotes a piezoelectric element, and the length of the piezoelectric element 8 in the stacking direction is longer than that in the horizontal direction orthogonal to the stacking direction. Further, the piezoelectric element 8 is displaced (extended) in the direction of arrow A by applying a voltage to the electrode 42 by the drive circuit 20 via the lead wire.

Reference numeral 31 denotes a pair of elastic members, each of which has a pair of holes 31b near both ends. Reference numeral 32 denotes a pair of tension members. Each of the pair of tension members 32 has a pair of projections 32a formed at both ends, and one of the tension members 32 further has a screw hole 32c. Reference numeral 33 denotes an adjusting screw. The adjusting screw 33 is screwed into a screw hole 32 c of the tension member 32 so that the urging force of the elastic member 31 can be increased or decreased.

These elastic members 31 and tension members 32
Is attached to the piezoelectric element 8, first, as shown in FIG. 3A, the protrusions 32 a of the pair of tension members 32 are respectively passed through the holes 31 b of the pair of elastic members 31, and Tightening the tension member 32 having the hole 32c,
The elastic member 31 is attached so that the outside thereof is depressed. Thereby, the curvature of the elastic member 31 and the piezoelectric element 8 of the elastic member 31 are determined.
Can be adjusted at the same time and simultaneously on both sides. The stopper member 36 is in contact with one of the elastic members 31 to function as a stopper.

In the piezoelectric element actuator having the above structure, when a voltage is applied to the piezoelectric element 8 via the drive circuit 20, the piezoelectric element 8 expands in the direction of arrow A, whereby the elastic member 31 causes the stop member 36 to move. Displaced in the direction of arrow B as a reference. That is, the elastic member 31 enlarges and converts the displacement in a direction perpendicular to the displacement direction (the laminating direction) of the piezoelectric element 8. This makes it possible to increase the displacement of the piezoelectric element 8 in the stacking direction.

FIG. 7 is a perspective view showing another example of the configuration of the piezoelectric element actuator according to the first embodiment of the present invention. In FIG. 7, this piezoelectric element actuator has an enlargement mechanism. That is, when a voltage is applied to the electrode 42 via the drive circuit 20, the piezoelectric element 8 extends in the longitudinal direction. When the piezoelectric element 8 extends in the longitudinal direction, the piezoelectric element 8
, The arm 43 is rotated counterclockwise about the shaft 44. By the rotation of the arm 43, the end on the long arm side expands in comparison with the expansion of the piezoelectric element 8, and the driving member 45 that moves freely along the guide 46 moves largely. The end of the driving member 45 in the moving direction is pressed by a spring 47,
The driving member 45 is nipped by the reaction force of the spring 47 and the long arm-side end of the arm 43, and moves the guide 45.

In this case, if the extension of the piezoelectric element 8 is made smaller than the maximum extension, the reaction force of the spring 47 becomes smaller, the friction between the shaft 44 and the arm 43 and the guide 46 of the drive member 45 become smaller. , The driving member 45 may not return to the original position even if the piezoelectric element 8 is discharged and the piezoelectric element is shortened.

Therefore, when acquiring the relationship between the number of charging pulses and the charging voltage stored in the voltage / pulse conversion table 13, the control unit 11 applies the voltage up to the maximum rated voltage to the piezoelectric element 8. Therefore, the piezoelectric element 8 can be extended to the maximum extent, and the reaction force of the spring 47 can be maximized to reliably return to the initial state.

As described above, according to the first embodiment, as an initial process, the relationship between the number of charging pulses and the charging voltage is obtained and converted into a conversion table, and the conversion table is converted into a voltage corresponding to a desired displacement using the conversion table. Since the corresponding number of charging pulses can be obtained immediately, the drive control of the piezoelectric element actuator can be performed at high speed.

The relationship between the number of charging pulses and the charging voltage is determined for every predetermined number k units, and the voltage / voltage is calculated from the determined value.
Since the pulse conversion table 13 is generated, the voltage / pulse conversion table 13 can be generated easily and quickly.

Further, when discharging the piezoelectric element, the piezoelectric element is charged to the maximum rated voltage and then discharged.
Highly reliable and highly accurate driving is achieved because the acquisition of the relationship between the number of charging pulses and the charging voltage in the entire range of drive control and the reliable return of the piezoelectric element actuator to the initial state are realized. Control can be performed, and even in a case where there is a displacement in which the friction of the driving member and the reaction force of the biasing spring are balanced, the reaction force of the biasing spring is maximized to ensure that the driving member And the biasing spring can be returned to the initial state, and the reliability of drive control of the piezoelectric element actuator thereafter can be improved.

Next, a second embodiment will be described. In the second embodiment, a polarization process is performed in addition to the initial process (step S100) in the first embodiment. FIG. 8 is a flowchart showing a drive control processing procedure including an initial process of the driving device of the piezoelectric element actuator according to the second embodiment of the present invention.
The second embodiment will be described based on this flowchart and the circuit diagram of FIG.

In FIG. 8, the control section 11 first determines whether or not power for driving the piezoelectric element actuator has been turned on (step S30). When the power is turned on (step S30, YES), an initial process (step S30)
The routine of 101) is executed by the relation acquisition unit 15. That is, first, the relationship acquisition unit 15 applies one charging pulse S1 to the base of the switching transistor 2 (Step S31). Further, the applied charging pulse S
The number n of 1 is counted (step S32).

Thereafter, the number n of the charging pulses S1 becomes a predetermined number k.
It is determined whether or not it is an integral multiple of (step S33). If it is not an integral multiple of the predetermined number k (step S33, NO), the process proceeds to step S31, and one more charging pulse S1 is applied. . On the other hand, if it is an integral multiple of the predetermined number k (step S33, YES), the voltage of the resistor 7 corresponding to the charging voltage of the piezoelectric element 8 is detected (step S3).
4) The relationship between the current number n of the charging pulses S1 and the detected voltage is stored (step S35).

Thereafter, it is determined whether or not the detected voltage has reached the maximum rated voltage (step S36). If the detected voltage has not reached the maximum rated voltage (step S36, NO), the flow shifts to step S31 to proceed to the next step. One charging pulse S1 is applied to the switching transistor 2, and the above-described processing is repeated. On the other hand, when the detected voltage has reached the maximum rated voltage (step S36, YES), the relationship acquisition unit 15 performs the voltage / pulse conversion table based on the relationship between the number of charging pulses S1 stored so far and the detected voltage. 13 is generated (step S37).

Thereafter, it is determined whether or not a predetermined time has elapsed while the maximum rated voltage is applied to the piezoelectric element 8 (step S38). If the predetermined time has elapsed (step S38,
Only in the case of (YES), the discharge pulse S3 is applied to the base of the switching transistor 10 to discharge the electric charge accumulated in the piezoelectric element 8 (step S39).

The voltage / pulse conversion table 13 is generated by the initial processing of steps S31 to S39 (step S101), and the polarization processing for the piezoelectric element 8 is executed.

Such an initial processing (step S101)
Is completed, step S20 in the first embodiment is performed.
Similarly to S24, the control unit 11 determines whether or not there is an instruction to actually drive the piezoelectric element actuator (step S40). If there is an instruction to actually drive the piezoelectric actuator (step S40, YES), The number of charging pulses S1 corresponding to the quantity input 21 is obtained, and the number of charging pulses S1 is applied to the base of the switching transistor 2 at a predetermined pulse frequency (step S41), and the piezoelectric element actuator is actually driven. The number of the charging pulses S1 is obtained by first obtaining the voltage corresponding to the displacement input 21 from the displacement / voltage conversion table 14, and further calculating the number of charging pulses corresponding to the obtained voltage from the voltage / pulse conversion table 13. Ask.

Thereafter, the controller 11 determines whether or not there is the next actual drive, that is, whether or not there is a displacement input 21 (step S).
42), when there is a displacement amount input 21 (step S42,
(YES), the discharge process is performed by applying the discharge pulse S3 to the base of the switching transistor 10 (step S44), and then the process proceeds to step S41 to determine the number of the charge pulses S1 corresponding to the displacement input 21. The process of applying the voltage to the base of the switching transistor 2 to actually drive the piezoelectric element is repeated. On the other hand, when there is no displacement amount input 21 (step S42, NO), the same discharge processing as step S44 is performed (step S43), and this processing ends.

Here, the polarization process will be described with reference to FIG. 9. As described above, the polarization process is to gradually apply a voltage to be used to the piezoelectric element 8 and, when a certain voltage is reached, a predetermined voltage is applied in this state. This is the process of aligning the direction of the polarizer by holding for a certain period of time and then discharging, and performs the polarization process at the time of device diagnosis, power-on, periodic or maintenance, and the function of the device due to polarization destruction. Reduction is prevented.

That is, in FIG. 9, the charging pulse S1
In the initial processing (step S101), the charging voltage applied to the piezoelectric element 8 is gradually increased at a predetermined pulse repetition frequency (steps S31 to S36), and the predetermined voltage, that is, the maximum rated voltage Vp, is reached for a predetermined time ( Steps S36 to S38), that is, during the time tp,
By maintaining this state and then applying a discharge pulse S3 to cause a discharge (step S39), a polarization process of aligning the directions of the polarizers is performed. This polarization process is performed in the voltage / pulse conversion table 13. It will be performed simultaneously with the acquisition process.

As a result, since it is not necessary to provide a time for the polarization processing, it is possible to shorten the overall processing time of the driving device of the piezoelectric element actuator, and to realize an efficient polarization processing.

Next, a third embodiment will be described. In the first embodiment, the initial processing (step S10
In generating the voltage / pulse conversion table 14 in (0),
The relationship between the number of charging pulses S1 and the charging voltage is determined for each predetermined number k units, and the conversion relationship is obtained from the determined relationship. However, in the third embodiment, each charging pulse S1
The conversion relationship is obtained by obtaining all the charging voltages for each unit.

FIG. 10 is a flow chart showing a drive control processing procedure including an initial processing of the driving device of the piezoelectric element actuator according to the third embodiment of the present invention, based on this flow chart and the circuit diagram of FIG. A third embodiment will be described.

In FIG. 10, the control section 11 first determines whether or not the power for driving the piezoelectric element actuator has been turned on (step S50). When the power is turned on (Step S50, YES), the routine of the initial processing (Step S102) is executed by the relation acquisition unit 15. That is, first, the relationship acquisition unit 15 applies one charging pulse S1 to the base of the switching transistor 2 (Step S51). Thereafter, the voltage of the resistor 7 corresponding to the charging voltage of the piezoelectric element 8 is detected (step S5).
2) The relationship between the current number n of the charging pulses S1 and the detected voltage is stored (step S53).

Thereafter, it is determined whether or not the detected voltage has reached the maximum rated voltage (step S54). If the detected voltage has not reached the maximum rated voltage (step S54, NO), the flow shifts to step S51 to proceed to the next step. One charging pulse S1 is applied to the switching transistor 2, and the above-described processing is repeated. On the other hand, when the detected voltage has reached the maximum rated voltage (step S54, YES), the relationship acquisition unit 15 performs the voltage / pulse conversion table based on the relationship between the number of charging pulses S1 stored so far and the detected voltage. 13 is generated (step S55).

Thereafter, it is determined whether or not a predetermined time has elapsed while the maximum rated voltage is applied to the piezoelectric element 8 (step S56). If the predetermined time has elapsed (step S56,
Only in the case of (YES), the discharge pulse S3 is applied to the base of the switching transistor 10 to discharge the electric charge accumulated in the piezoelectric element 8 (Step S57).

By the initial processing of steps S51 to S56 (step S102), the voltage / pulse conversion table 13 based on the charging voltage for each charging pulse is generated, and the polarization processing for the piezoelectric element 8 is executed. Will be.

Such an initial process (step S102)
Is completed, step S20 in the first embodiment is performed.
Similarly to S24, the control unit 11 determines whether there is an instruction to actually drive the piezoelectric element actuator (step S60), and when there is an instruction to actually drive (step S60, YES), The number of charging pulses S1 corresponding to the quantity input 21 is obtained, and the number of charging pulses S1 is applied to the base of the switching transistor 2 at a predetermined pulse frequency (step S61), and the piezoelectric element actuator is actually driven. The number of the charging pulses S1 is obtained by first obtaining the voltage corresponding to the displacement input 21 from the displacement / voltage conversion table 14, and further calculating the number of charging pulses corresponding to the obtained voltage from the voltage / pulse conversion table 13. Ask.

Thereafter, the control unit 11 determines whether or not there is the next actual drive, that is, whether or not there is a displacement input 21 (step S).
62) If there is a displacement amount input 21 (step S62,
In YES, the discharge pulse S3 is applied to the base of the switching transistor 10 to perform a discharge process (step S64). Then, the process proceeds to step S61, where the number of the charge pulses S1 corresponding to the displacement input 21 is calculated. The process of applying the voltage to the base of the switching transistor 2 to actually drive the piezoelectric element is repeated. On the other hand, when there is no displacement amount input 21 (step S62, NO), the same discharge processing as step S64 is performed (step S63), and this processing ends.

In the third embodiment, all the charging voltages of the piezoelectric element 8 for each charging pulse are obtained, and the relationship between the number of charging pulses and the charging voltage is obtained from the obtained value. Further, highly accurate drive control can be performed.

Next, a fourth embodiment will be described. In the fourth embodiment, when the above-described first to third embodiments are performed, the power supply voltage fluctuates or the environmental conditions change, and the voltage / pulse conversion table 13 is reacquired. The driving process is performed based on the reacquired voltage / pulse conversion table 13.

FIG. 11 shows a relation monitoring unit 1 of a driving device for a piezoelectric element actuator according to a fourth embodiment of the present invention.
6 is a flowchart showing the overall processing procedure including the processing of the power supply monitoring unit 6 and the power supply monitoring unit 17. The fourth embodiment will be described based on this flowchart and the circuit diagram of FIG.

In FIG. 11, the control unit 11 first determines whether or not power for driving the piezoelectric element actuator has been turned on (step S70). When the power is turned on (step S70, YES), the relationship acquisition unit 15 executes a subroutine of an initial process (step S71) for acquiring the voltage / pulse conversion table 13 including the polarization process. The initial process of step S71 may use any of the initial processes of steps S100 to S102 described above.

Thereafter, the control section 11 determines whether or not there is an instruction to actually drive the piezoelectric element actuator (step S72). If there is an instruction to actually drive the piezoelectric element actuator (step S72, YES), the control section 11 further proceeds to step S72. It is determined whether or not the monitoring result of the power supply monitoring unit 16 indicates that the power supply voltage value is out of the allowable range (step S73), and if the power supply voltage value is out of the allowable range (step S73, YES). Is
The process shifts to step S71 to cause the initialization process to be performed again to perform the process of acquiring the voltage / pulse conversion table 13 at the current power supply voltage.

On the other hand, if the power supply voltage value is not outside the allowable range (step S73, NO), the number of charging pulses S1 corresponding to the displacement input 21 is obtained, and the number of charging pulses S1 is determined by the switching transistor 2. A voltage is applied to the base at a predetermined pulse frequency (step S74), and the piezoelectric element actuator is actually driven. The number of the charging pulses S1 is
First, a voltage corresponding to the displacement input 21 is obtained from the displacement / voltage conversion table 14, and the number of charging pulses corresponding to the obtained voltage is calculated by the voltage / pulse conversion table 1.
Find from 3.

Thereafter, the control section 11 further causes the relation monitoring section 16 to detect a voltage detection signal S2 which is a charging voltage of the piezoelectric element 8 (step S75), and the relation monitoring section 16 determines the value of the voltage detection signal S2. It is determined whether an error between the charging voltage value corresponding to the current charging pulse number obtained from the conversion relationship of the voltage / pulse conversion table 13 and the detected current charging voltage value is outside the allowable range ( Step S7
6).

The control unit 11 determines that the error between the charging voltage value of the voltage / pulse conversion table 13 corresponding to the current charging pulse number and the detected current charging voltage value is outside the allowable range (step S76). , YES), the process proceeds to step S71, where the initial process is performed again, and the process of acquiring the voltage / pulse conversion table 13 in the current environment is performed.

On the other hand, when the error between the charging voltage value in the voltage / pulse conversion table 13 corresponding to the current charging pulse number and the detected current charging voltage value is not outside the allowable range (step S7).
6, NO), the controller 11 determines whether or not there is the next actual drive, that is, whether or not there is a displacement input 21 (step S77).
When there is a displacement amount input 21 (step S77, YES)
The discharge pulse S3 is supplied to the switching transistor 10
(Step S7)
9) Thereafter, the flow shifts to step S73, and the displacement amount input 2
The process of applying the number of charging pulses S1 corresponding to 1 to the base of the switching transistor 2 and actually driving the piezoelectric element is repeated. On the other hand, when there is no displacement amount input 21 (step S77, NO), the same discharge process as in step S79 is performed (step S78), and this process ends.

When it is determined in step S73 that the power supply voltage value is out of the allowable range, the power supply monitoring unit 1
In step S7, the process may shift to step S71 after notifying that the power supply voltage value is out of the allowable range. Thus, the operator using the device equipped with the driving device for the piezoelectric actuator knows that the power supply voltage value has fallen out of the allowable range, and can take a predetermined measure corresponding thereto.

In the fourth embodiment, when the power supply voltage fluctuates outside the allowable range or when the conversion relationship of the voltage / pulse conversion table 13 becomes incompatible due to a temperature change or the like, a new voltage / pulse is immediately generated. The conversion table 13 is reacquired, and the reacquired voltage / pulse conversion table 13
Since the driving process is performed by using, the driving control with high accuracy corresponding to the displacement input 21 can always be performed.

Next, a fifth embodiment will be described. FIG. 12 is a circuit diagram of the driving device of the piezoelectric element actuator according to the fifth and sixth embodiments of the present invention. The driving device of the piezoelectric element actuator according to the first to fourth embodiments shown in FIG. The configuration is such that a pulse frequency setting unit 18 is added to the control unit 11 in the configuration.
Other configurations are the same as those of the circuit diagram shown in FIG.
12, parts having the same configuration are denoted by the same reference numerals, and description of the configuration will be omitted. Also, the drive control process of the control unit 11 can apply any of the first to fourth embodiments.

The pulse frequency setting unit 18 sets the pulse frequency of the charging pulse S1 to an optimum pulse frequency, and the control unit 11 applies the charging pulse S1 having the set pulse frequency to the base of the switching transistor 2. Thus, the driving of the piezoelectric element 8 is controlled. The optimum pulse frequency refers to a pulse frequency at which the charging pulse S1 of the base of the switching transistor 2 is applied to charge the piezoelectric element 8 at a predetermined voltage, here the maximum rated voltage, at the highest speed. By setting such an optimal pulse frequency and using it at the time of driving, it is possible to drive and control the piezoelectric element actuator at high speed.

Next, an initial processing operation procedure of the driving device for the piezoelectric element actuator according to the fifth embodiment of the present invention will be described with reference to the flowchart of FIG. In FIG. 13, the pulse frequency setting unit 18 of the control unit 11 sets a preset initial pulse frequency as the pulse frequency of the charging pulse S1 (step S8).
0). Thereafter, the timer starts counting (step S81), and the relationship acquisition unit 15 applies one charging pulse S1 to the base of the switching transistor 2 (step S82). Further, the relationship acquisition unit 15 counts the number n of the applied charging pulses S1 (step S8).
3).

After that, the relation acquiring unit 15 sets the charging pulse S
It is determined whether or not the number n of 1 is an integer multiple of the predetermined number k (step S84). If the number n is not an integer multiple of the predetermined number k (step S84, NO), the process proceeds to step S82 and further proceeds to 1 One charging pulse S1 is applied. On the other hand, if it is an integral multiple of the predetermined number k (step S84, YES), the voltage of the resistor 7 corresponding to the charging voltage of the piezoelectric element 8 is detected (step S85), and the number n of the current charging pulse S1 is detected.
Is stored (step S8).
6).

Thereafter, it is determined whether or not the detected voltage has reached the maximum rated voltage (step S87). If the detected voltage has not reached the maximum rated voltage (step S87, NO), the flow shifts to step S87 to proceed to the next step. One charging pulse S1 is applied to the switching transistor 2, and the above-described processing is repeated. On the other hand, if the detected voltage has reached the maximum rated voltage (step S87, YES), the count time of the timer is stored in association with the current pulse frequency (step S87).
88).

Thereafter, it is determined whether or not there is a next pulse frequency for determining the optimum pulse frequency (step S).
89) If there is a next pulse frequency (step S8)
(9, YS), a discharge pulse S3 is applied to the base of the switching transistor 10 to discharge the charge accumulated in the piezoelectric element 8 (step S90), and the next pulse frequency is set as the pulse frequency (step S91). )
Thereafter, the process proceeds to step S81, and as described above, the process of acquiring the relationship between the number of charging pulses and the charging voltage based on the set pulse frequency and the process of measuring the time until reaching the maximum rated voltage are repeatedly performed.

On the other hand, there is no next pulse frequency for determining the optimum pulse frequency, that is, the process of obtaining the relationship between the number of charging pulses and the charging voltage for all candidate pulse frequencies and the time until the maximum rated voltage is reached. Is completed, the pulse frequency setting unit 18 determines the pulse frequency with the shortest count time to reach the maximum rated voltage, and uses the determined pulse frequency as the optimal pulse frequency to be used in the driving process. It is set (step S92).

After that, the relation acquisition unit 15 generates the voltage / pulse conversion table 13 based on the relation between the charging pulse number and the charging voltage corresponding to the set optimum pulse frequency (step S93). The discharge pulse S3 is applied to the base of the switching transistor 10 to discharge the charge accumulated in the piezoelectric element 8 (Step S94), and the present initial processing ends.

In the above-described initial processing, the processing corresponding to the first embodiment for acquiring the relationship between the number of charging pulses and the charging voltage at every predetermined number k is applied as the fifth embodiment. I have. Therefore, it is clear that the processing corresponding to the second to fourth embodiments can be applied as the fifth embodiment.

As described above, in the fifth embodiment,
In the initial processing, the optimum pulse frequency is determined, and the drive processing is performed using the determined pulse frequency. Therefore, a higher-speed drive processing is realized.

Next, a sixth embodiment will be described. In the fifth embodiment, the relationship between the number of charging pulses and the charging voltage was obtained for all the pulse frequencies in determining the optimum pulse frequency. However, in the sixth embodiment,
First, the optimum pulse frequency is determined, and then the relationship between the number of charging pulses and the charging voltage with respect to the determined pulse frequency is determined.

FIGS. 14 and 15 are flowcharts showing the initial processing operation procedure of the driving device of the piezoelectric element actuator according to the sixth embodiment of the present invention. The sixth embodiment will be described with reference to this flowchart and FIG. An initial processing operation procedure in the embodiment will be described.

In FIG. 14, the pulse frequency setting unit 18 of the control unit 11 sets a preset initial pulse frequency as the pulse frequency of the charging pulse S1 (step S110). Thereafter, the timer starts counting (step S111), and the relationship acquisition unit 15 applies one charging pulse S1 to the base of the switching transistor 2 (step S112).

Thereafter, it is determined whether a predetermined time has elapsed (step S113). The predetermined time means that the piezoelectric element 8 uses various pulse frequencies as the charging pulse S1.
Is the time it takes to reach the maximum rated voltage. This predetermined time is provided because the charging voltage is not detected every time a charging pulse is applied or every predetermined number k. If the predetermined time has not elapsed (step S113, N
In O), the process proceeds to step S112, and a charging pulse is further applied. On the other hand, if the predetermined time has elapsed (step S113, YES), the charging voltage at this time is detected (step S114), and the detected voltage is stored in association with the pulse frequency (step S115).

Thereafter, it is determined whether or not there is a next pulse frequency for determining the optimum pulse frequency (step S).
116) If there is a next pulse frequency (step S1)
(16, YES), a discharge pulse S3 is applied to the base of the switching transistor 10 to discharge the charge accumulated in the piezoelectric element 8 (step S117), and the next pulse frequency is set as the pulse frequency (step S1).
18) Then, the process proceeds to step S111, and as described above, the process of measuring the charging voltage at the elapse of the predetermined time by the set pulse frequency is repeated.

On the other hand, if there is no next pulse frequency for determining the optimum pulse frequency, that is, if the process of measuring the charging voltage after a predetermined time with respect to all the candidate pulse frequencies is completed, the pulse frequency setting unit 18 Then, a pulse frequency at which the measured charging voltage is the highest is determined, and the determined pulse frequency is set as an optimal pulse frequency to be used for the driving process (step S119).

After that, the pulse frequency setting section 18 applies the discharge pulse S3 to the base of the switching transistor 10 to discharge the electric charge accumulated in the piezoelectric element 8 (Step S120).

The processing up to this point, that is, step S11
The processing from 0 to S120 is the processing for determining the optimum pulse frequency.

When the optimum pulse frequency is determined and set, the control section 11 performs the same operation as in step S100.
A process of acquiring the relationship between the number of charging pulses and the charging voltage and generating the voltage / pulse conversion table 13 is performed.

That is, in FIG. 15, the relationship acquisition unit 15 of the control unit 11 applies one charging pulse S1 to the base of the switching transistor 2 (step S12).
1) Count the number n of applied charging pulses S1 (step S122).

After that, the relation obtaining unit 15 sets the charging pulse S
It is determined whether or not the number n of 1 is an integer multiple of the predetermined number k (step S123). If the number n is not an integer multiple of the predetermined number k (step S123, NO), the process proceeds to step S121, and further 1 One charging pulse S1 is applied. on the other hand,
When it is an integral multiple of the predetermined number k (step S123, YE
In S), the voltage of the resistor 7 corresponding to the charging voltage of the piezoelectric element 8 is detected (step S124), and the current charging pulse S
The relationship between the number n of 1s and the detected voltage is stored (step S125).

Thereafter, it is determined whether or not the detected voltage has reached the maximum rated voltage (step S126). If the detected voltage has not reached the maximum rated voltage (step S126, NO), the flow shifts to step S121 to proceed to the next step. One charging pulse S1 is applied to the switching transistor 2, and the above-described processing is repeated. On the other hand, when the detected voltage has reached the maximum rated voltage (step S121, YES), the voltage / pulse conversion table 13 is generated from the stored relationship between the number of charging pulses and the charging voltage (step S127). Further, a discharge pulse S3 is applied to the base of the switching transistor 10 to discharge the electric charge accumulated in the piezoelectric element 8 (step S128), and the initial processing ends. Note that the processes in steps S121 to S128 have been described as the same processes as those in step S100.
01, S102, etc. can also be applied.

In the sixth embodiment, the process of determining and setting the optimum pulse frequency and the process of obtaining the voltage / pulse conversion table 13 are divided, and the process of obtaining the voltage / pulse conversion table 13 is determined. Since the process is performed only for the appropriate pulse frequency, the charge voltage detection process for obtaining the useless voltage / pulse conversion table 13 does not need to be performed, so that an efficient initial process can be executed.

Next, a camera using the driving device of the piezoelectric element actuator according to the first to sixth embodiments will be described. FIG. 16 is a block diagram functionally showing a configuration of a camera using a driving device for a piezoelectric element actuator according to a seventh embodiment of the present invention. FIG.
In 6, the light from the subject input to the optical system 50 is received by an imaging device 51 such as a CCD imaging device or a CMOS imaging device, and is converted into an image signal.
The image signal of each pixel received by the image sensor 51 is
The horizontal and vertical driving control is performed by the drive unit 61 and output to the amplifier 52. The analog image signal amplified by the amplifier 52 is converted into a digital image signal by the A / D converter 53. The digital image signal is
In addition to facilitating storage in a memory, various image processing can be performed.
Done by The image signal processed by the signal processing circuit 54 is output to the output circuit 55 and stored and output as image data. On the other hand, the signal processing circuit 54 outputs various information for controlling the driving unit 61 or the driving circuit to the control unit 57.

The control section 57 corresponds to the control section 11 shown in FIG. 1 or FIG.
Of the driving circuit 20.

The optical system 50 constitutes a lens system,
It has a focusing lens, and this focusing (focusing processing) is driven by a piezoelectric element actuator 59. The optical system 50 may be a lens system such as a telephoto lens, a wide-angle lens, and a zoom lens, in addition to a standard lens, and may control the driving of elements constituting each lens system, for example, a variator. Good.

Further, a focusing process may be performed by providing a piezoelectric element actuator 60 for moving the image pickup device 51 in the optical axis direction and moving the image pickup device 51 in the optical axis direction. In addition to the focusing processing, control such as camera shake correction can be performed using the piezoelectric element actuators 59 and 60.

When the camera is driven, the control unit 57 performs, for example, the initial processing according to the above-described first to sixth embodiments. This makes it possible to drive the piezoelectric element actuators 59 and 60 at high speed.

Next, an eighth embodiment will be described. In the above-described first to seventh embodiments, the driving process for the piezoelectric element actuator determines the voltage value corresponding to the displacement amount from the displacement / voltage conversion table 14, and calculates the number of charging pulses corresponding to the determined voltage value. The voltage / pulse conversion table 13 is used to drive the piezoelectric element 8 at a high speed by applying the obtained number of charging pulses to the switching transistor 2. However, in the eighth embodiment, This is to drive the piezoelectric element actuator at high speed by the minimum initial processing required for the focusing processing.

FIG. 17 is a block diagram functionally showing a configuration of a camera using a driving device for a piezoelectric element actuator according to an eighth embodiment of the present invention. In FIG. 17, this camera uses a CCD image pickup device or a CM
The light is received by an image sensor 51 such as an OS image sensor and converted into an image signal. The image signal of each pixel received by the image sensor 51 is subjected to horizontal and vertical drive control by the drive unit 61 and output to the amplifier 52.
The analog image signal amplified by 2 is converted into a digital image signal by the A / D converter 53. The digital image signal can be easily stored in a memory and the like, and various image processes can be performed. These processes are performed by a signal processing circuit 54. The image signal processed by the signal processing circuit 54 is output to an output circuit 55
And stored and output as image data. on the other hand,
Various information for controlling the drive unit 61 or the drive circuit is output from the signal processing circuit 54 to the control unit 70.

Here, a high-pass filter 56 is provided in the signal processing circuit 54, and the high-frequency component signal of the image signal obtained through the high-pass filter 56 is input to the control unit 70. The drive circuit 58 corresponds to the drive circuit 20 of FIG. 1 or FIG. 12, and the control unit 70 controls the drive of the drive circuit 20 and the drive unit 61.

The optical system 50 constitutes a lens system,
It has a focusing lens, and this focusing (focusing processing) is driven by a piezoelectric element actuator 59. The optical system 50 may be a lens system such as a telephoto lens, a wide-angle lens, and a zoom lens, in addition to a standard lens, and may control the driving of elements constituting each lens system, for example, a variator. Good.

Further, the focusing process may be performed by providing a piezoelectric element actuator 60 for moving the image sensor 51 in the optical axis direction and moving the image sensor 51 in the optical axis direction.

The control section 70 has a pulse / high frequency relation acquisition section 71, a charging pulse number determination section 72, and a memory 73. The pulse / high-frequency relationship acquisition unit 71 acquires the relationship between the number of charging pulses and the high-frequency component value based on the high-frequency component signal output from the high-pass filter 56. The charging pulse number determination unit 72 determines the charging pulse number when the high frequency component value is the largest based on the relationship acquired by the pulse / high frequency relationship acquisition unit 71. The memory stores programs and data for various controls.

Here, the focusing procedure of the camera using the driving device of the piezoelectric element actuator according to the eighth embodiment of the present invention will be described with reference to the flowchart of FIG. In FIG. 18, first, the control unit 70
Determines whether or not to perform a pre-scan for the focusing process (step S130), and only when performing the pre-scan (step S130, YES), the pulse / high-frequency relationship acquisition unit 71 determines whether one charging pulse S1 Is applied to the base of the switching transistor 2 (step S131).
Further, the number n of the applied charging pulses S1 is counted (step S132).

Thereafter, the pulse / high frequency relation acquisition section 71
Acquires the high-frequency component value from the high-pass filter 56 when the charging pulse S1 is applied (step S13).
3) The relationship between the number n of the charging pulses S1 at this time and the high-frequency component value is stored in the memory 73 (step 134).

Thereafter, it is determined whether or not the prescan has been completed (step S135). If the prescan has not been completed (step S135, NO), the process proceeds to step S1.
Then, the process goes to 31 to repeatedly acquire the relationship between the number of charging pulses and the high-frequency component value.

On the other hand, when the pre-scan is completed (step S135, YES), the discharge is performed by applying the discharge pulse S3 to the base of the switching transistor 10 (step S136).

Thereafter, the charging pulse number determining section 72 obtains the charging pulse number corresponding to the maximum high frequency component value from the relationship between the charging pulse number and the high frequency component value stored in the memory 7 (step S137). Then, the charging pulse S1 of the obtained number of charging pulses is applied to the base of the switching transistor 2 to drive the piezoelectric element actuator 59 or 60 suitable for the focusing process (step S13).
8), end this processing.

[0135] Focusing most when having the maximum high-frequency component value means that there are many high-frequency components where the rate of change of the distribution of lightness or the like on the image is large, and when the value of this high-frequency component becomes large, the focus is increased. It is based on the principle that As one of such focusing processes, a so-called hill-climbing method is known.

FIG. 19 is a diagram showing the relationship between the number of charging pulses and the high-frequency component value acquired by the pulse / high-frequency relationship acquiring section 71 of FIG. In FIG. 19, at the time of the pre-scan, the piezoelectric element actuator is driven with an increase in the number of charging pulses, and as a result, the focusing lens or the imaging element 51 in the optical system 50 moves. At the focus position, the high-frequency component value becomes the maximum value.

Therefore, in the above-described eighth embodiment,
The pulse / high-frequency relationship acquisition unit 71 acquires the relationship between the number of charging pulses at the time of pre-scanning and the high-frequency component value at the time of pre-scanning, and performs the maximum focusing component value when performing actual focusing processing. Is determined, and the determined number of charging pulses PP is applied.
Focusing processing is performed at high speed.

In this case, unlike the first to seventh embodiments, it is needless to say that the voltage / pulse conversion table 13 does not need to be obtained as the initial processing, and that the displacement / voltage conversion table 14 need not be provided. No. Of course, the configuration shown in the first to seventh embodiments may be combined. However, when the focusing process is performed, the configurations shown in the first to seventh embodiments are not used. Therefore, in the eighth embodiment, the focusing process can be performed by driving the piezoelectric element actuator at a high speed with a simple configuration.

In the above-described embodiment, when the number of charging pulses corresponding to this voltage is obtained from the voltage corresponding to the amount of displacement, or when the number of charging pulses is obtained from the maximum high-frequency component value, the number of charging pulses is reduced. In some cases, the number of charging pulses cannot be determined immediately because of the integer. .

In the above-described embodiment, a camera has been described as an example of a device using a driving device for a piezoelectric element actuator. However, it is apparent that the present invention can be applied to a video camera due to its structure.

[0141]

As described above, according to the first aspect of the present invention, the acquisition means causes the piezoelectric element to be charged by applying the charging pulse after the power is turned on and before the piezoelectric element is actually driven. Obtain the relationship between the number of charging pulses during charging and the charging voltage detected by the detection unit, create a conversion table that defines this relationship, and when the drive control unit actually drives the piezoelectric element, The number of charging pulses corresponding to the amount of voltage corresponding to the amount of displacement of the piezoelectric element is converted based on the relationship stored in the conversion table, and the charging pulses of the converted number of charging pulses are applied. The piezoelectric element is actually driven without performing voltage control by the voltage detection means, and the drive control of the piezoelectric element actuator can be performed at high speed. Since so as to obtain the relationship between the charging voltage, there is an effect that it also possible to reduce the influence due to the change in temperature or the like environment for the drive of the piezoelectric element actuator.

According to the second aspect of the present invention, when acquiring the relationship between the number of charging pulses and the charging voltage, the acquiring means performs charging up to the maximum rated voltage of the piezoelectric element, and acquires polarization at the time of acquiring the relationship. Since it is not necessary to provide the time for performing the polarization processing of the piezoelectric element by performing the processing at the same time, it is possible to reduce the overall processing time required for the driving processing of the piezoelectric element actuator.

According to the third aspect of the present invention, when acquiring the relationship between the number of charging pulses and the charging voltage, the acquiring means detects the charging voltage for each predetermined number of pulses by the voltage detecting means. Since the relationship between the number of charging pulses and the charging voltage is obtained, the time required to obtain the relationship between the number of charging pulses and the charging voltage is reduced,
This has the effect of saving power consumption.

According to the fourth aspect of the present invention, when acquiring the relationship between the number of pulses for charging and the charging voltage, the acquiring unit causes the voltage detecting unit to detect the charging voltage for each pulse, and Since the relationship between the number of charging pulses and the charging voltage is obtained, the relationship between the number of charging pulses and the charging voltage can be accurately obtained, and the drive control of the piezoelectric element can be performed with high accuracy. This has the effect.

According to the fifth aspect of the present invention, when acquiring the relationship between the number of charging pulses and the charging voltage, the obtaining means changes the pulse frequency of the charging pulse to charge the battery at the highest speed to a predetermined voltage. The drive control means obtains a pulse frequency, and the drive control means controls the drive of the piezoelectric element based on the number of charge pulses having the pulse frequency acquired by the acquisition means. Therefore, the drive control of the piezoelectric element actuator can be performed at a high speed.

According to the invention of claim 6, the power supply monitoring means monitors whether the power supply voltage of the power supply for charging the piezoelectric element is within a predetermined allowable range, and the power supply voltage is within the predetermined allowable range. If not, the relationship between the number of charging pulses and the charging voltage is reacquired, the relationship between the number of charging pulses and the charging voltage stored in the conversion table is updated, and the charging pulse Since the relationship between the number of charging pulses and the charging voltage is corrected quickly, even if there is a change in the battery voltage that affects the relationship between the number of charging pulses and the charging voltage from power-on, the charging pulse The relationship between the number and the charging voltage is promptly corrected, so that there is an effect that reliable drive control can be performed.

According to the seventh aspect of the present invention, the relation monitoring means measures the voltage immediately before the discharge of the piezoelectric element, and based on the relation between the number of charging pulses and the charging voltage stored in the conversion table. Detecting whether or not the difference between the measured voltage and the charging voltage corresponding to the number of charging pulses at the time of the measurement is within a predetermined range; and if the difference is not within the predetermined range, the charging pulse number and charging are detected. The relationship with the voltage is reacquired, the relationship between the number of charging pulses and the charging voltage stored in the conversion table is updated, and the relationship between the number of charging pulses and the charging voltage is quickly corrected. Therefore, when a temperature change or the like occurs after the power is turned on in the circuit system of the driving device, the relationship between the number of charging pulses and the charging voltage may change. The relationship between the number of pulses for use and the charging voltage Since Ya either modified, an effect that it is possible to perform the driving control reliable.

According to an eighth aspect of the present invention, when the discharging of the piezoelectric element is performed, the obtaining means charges the piezoelectric element to a maximum rated voltage and then discharges the piezoelectric element. Since the acquisition of the relationship between the number of pulses and the charging voltage, appropriate polarization processing, and reliable return of the piezoelectric element actuator to the initial state are realized, highly reliable and highly accurate drive control is performed. In addition to the above, even when there is a displacement such that the friction of the driving member and the reaction force of the biasing spring are balanced,
By maximizing the reaction force of the biasing spring, the drive member and the biasing spring can be reliably returned to the initial state, and the effect of increasing the reliability of the drive control of the piezoelectric element actuator thereafter can be improved. Play.

According to the ninth aspect of the present invention, a camera having the above-mentioned effects of the first to eighth aspects is realized. For example, the driving control of the piezoelectric element is performed only by the number of charging pulses without detecting the charging voltage of the piezoelectric element. Is performed, the piezoelectric element can be driven at high speed, and a camera that does not miss a shutter chance can be realized. In addition, for example, the piezoelectric element actuator can be controlled to move a focusing lens or an imaging element. In this case, high-speed and highly-reliable control can be performed for the focusing processing control and the camera shake correction control of the camera.

According to the tenth aspect of the present invention, the high frequency component detected by the high frequency component detecting means has the maximum value during the prescan when the pulse number obtaining means drives the driving means to perform a focusing process. When the number of charging pulses at the time is obtained, the drive control unit discharges the piezoelectric element charged at the time of the prescan, and then supplies the charging pulse of the charging pulse number obtained by the pulse number obtaining unit to the piezoelectric element. Since the focusing process is performed by applying the actual drive for focusing by applying the voltage, the focusing process can be realized with a high-speed and simple configuration without detecting the charging voltage of the piezoelectric element. This has the effect that it can be performed.

According to the eleventh aspect of the present invention, first,
The relationship between the amount of input displacement and the charging voltage of the piezoelectric element was held in advance, and the relationship between the charging voltage of the piezoelectric element and the number of charging pulses was acquired and held after the power was turned on and before the piezoelectric element was actually driven. The charging voltage for the input displacement amount is obtained from the relationship, the number of charging pulses for the obtained charging voltage is obtained from the obtained relation, and the charging pulse of the obtained number of charging pulses is applied to actually drive the piezoelectric element. To control the
Since the actual driving of the piezoelectric element can be performed at high speed without detecting the charging voltage, and after the power is turned on, the relationship between the number of charging pulses and the charging voltage is obtained.
There is an effect that the influence of a change in environment such as temperature on the driving device of the piezoelectric element actuator can be reduced.

According to the twelfth aspect of the present invention, the piezoelectric element is charged up to the maximum rated voltage to obtain the relationship between the charging voltage of the piezoelectric element and the number of charging pulses, and the polarization processing is also performed. Therefore, there is no need to provide a time required for the polarization process, so that the entire processing time required for driving the piezoelectric element actuator can be reduced.

According to the thirteenth aspect, the charging voltage applied to the piezoelectric element is detected for each predetermined number of pulses, and the relationship between the charging voltage of the piezoelectric element and the number of charging pulses is obtained. Therefore, it is possible to shorten the time required for obtaining the relationship between the number of charging pulses and the charging voltage, thereby achieving an effect of saving power consumption.

According to the fourteenth aspect of the present invention, the charging voltage applied to the piezoelectric element is detected for each pulse, and the relationship between the charging voltage of the piezoelectric element and the number of charging pulses is obtained. The relationship between the number of charging pulses and the charging voltage can be accurately obtained, and the driving of the piezoelectric element can be accurately controlled.

According to the fifteenth aspect of the present invention, first, the pulse frequency of the piezoelectric element is changed to determine the pulse frequency for charging at the highest speed to a predetermined voltage, and the charging voltage of the piezoelectric element at the determined pulse frequency is determined. Since the relationship with the number of charging pulses is obtained, and the piezoelectric element actuator is driven by the charging pulse having the obtained pulse frequency, the driving control of the piezoelectric element actuator can be performed at high speed. To play.

According to the sixteenth aspect of the present invention, it is monitored whether or not the power supply voltage of the power supply for charging the piezoelectric element is within a predetermined allowable range. Since the relationship between the number of charging pulses and the charging voltage is reacquired and the relationship between the number of charging pulses and the charging voltage is quickly corrected, the number of charging pulses and the Even when there is a change in the battery voltage that affects the relationship with the voltage, the relationship between the number of charging pulses and the charging voltage is quickly corrected, so that there is an effect that reliable drive control can be performed.

According to the seventeenth aspect, first, the voltage immediately before the discharge of the piezoelectric element is measured, and based on the relationship between the number of charging pulses obtained in the obtaining step and the charging voltage,
It detects whether the difference between the measured voltage and the charging voltage corresponding to the number of charging pulses at the time of the measurement is within a predetermined range, and according to the result, when the difference is not within the predetermined range, the charging is performed. The relationship between the number of charging pulses and the charging voltage is reacquired, and the relationship between the number of charging pulses and the charging voltage is corrected quickly, so that a temperature change or the like occurs in the circuit system of the driving device after the power is turned on. In such a case, the relationship between the number of charging pulses and the charging voltage may change, but also in such a case, the relationship between the number of charging pulses and the charging voltage is quickly corrected. There is an effect that reliable drive control can be performed.

According to the eighteenth aspect of the present invention, when discharging the piezoelectric element, the piezoelectric element is charged to the maximum rated voltage and then discharged, and the number of charging pulses and the charging voltage in the entire range of drive control are controlled. And the appropriate polarization processing, and to ensure that the piezoelectric element actuator returns to the initial state, high reliability,
And high-precision drive control can be performed.
In particular, even when there is a displacement such that the friction of the driving member and the reaction force of the biasing spring are balanced, the reaction force of the biasing spring is maximized, and the driving member and the biasing spring are securely placed in the initial state. And the reliability of drive control of the piezoelectric element actuator thereafter can be improved.

According to the nineteenth aspect, first, at the time of prescanning before the actual driving of the piezoelectric element actuator for driving the focusing mechanism, a charging pulse is applied to displace the piezoelectric element in the piezoelectric element actuator. The relationship between the number of charging pulses at this time and the high-frequency component value of the image signal of the subject imaged via the focusing mechanism is obtained, and then the relationship between the obtained number of charging pulses and the high-frequency component value is obtained. Based on the relationship, determine the number of charging pulses when the high-frequency component value is maximum, and further, after discharging the piezoelectric element charged at the time of the pre-scan, charge pulses of the determined number of charging pulses. Since the focusing process is performed by applying to the piezoelectric element, without detecting the charging voltage of the piezoelectric element,
There is an effect that the focusing process can be realized at high speed with a simple configuration.

According to a twentieth aspect of the present invention, a recording medium stores a program for causing a computer to execute the method according to any one of the eleventh to nineteenth aspects.
The program can be machine-readable, thereby providing an effect that the operations of claims 11 to 19 can be realized by a computer.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a driving device of a piezoelectric element actuator according to first to fourth embodiments of the present invention.

FIG. 2 is a flowchart showing a drive control processing procedure including an initial processing of the driving device of the piezoelectric element actuator according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a relationship between the number of charging pulses and a charging voltage acquired by a relationship acquiring unit 15 of the driving device for a piezoelectric element actuator according to the first embodiment of the present invention.

FIG. 4 is a voltage / pulse conversion table 1 of the driving device of the piezoelectric element actuator according to the first embodiment of the present invention.
FIG. 3 is a diagram showing an example of contents stored in No. 3;

FIG. 5 is a voltage / pulse conversion table 1 of the driving device for the piezoelectric element actuator according to the first embodiment of the present invention.
FIG. 3 is a diagram showing an example of contents stored in No. 3;

FIG. 6 is a perspective view showing an example of the configuration of the piezoelectric element actuator according to the first embodiment of the present invention.

FIG. 7 is a perspective view showing an example of a configuration of a piezoelectric element actuator according to the first embodiment of the present invention.

FIG. 8 is a flowchart showing a drive control processing procedure including an initial processing of a driving device of a piezoelectric element actuator according to a second embodiment of the present invention.

FIG. 9 is an explanatory diagram illustrating a polarization process included in FIG. 8;

FIG. 10 is a flowchart showing a drive control processing procedure including an initial processing of a driving device of a piezoelectric element actuator according to a third embodiment of the present invention.

FIG. 11 is a flowchart showing an overall processing procedure including processing of a relation monitoring unit 16 and a power supply monitoring unit 17 of a driving device for a piezoelectric element actuator according to a fourth embodiment of the present invention.

FIG. 12 is a circuit diagram of a driving device for a piezoelectric element actuator according to fifth and sixth embodiments of the present invention.

FIG. 13 is a flowchart showing an initial processing operation procedure of a driving device for a piezoelectric element actuator according to a fifth embodiment of the present invention.

FIG. 14 is a flowchart illustrating an initial processing operation procedure of a driving device of a piezoelectric element actuator according to a sixth embodiment of the present invention (part 1).

FIG. 15 is a flowchart showing an initial processing operation procedure of the driving device of the piezoelectric element actuator according to the sixth embodiment of the present invention (part 2).

FIG. 16 is a block diagram functionally showing a configuration of a camera using a driving device for a piezoelectric element actuator according to a seventh embodiment of the present invention.

FIG. 17 is a block diagram functionally showing a configuration of a camera using a driving device for a piezoelectric element actuator according to an eighth embodiment of the present invention.

FIG. 18 is a flowchart showing a focusing operation procedure of a camera using a driving device for a piezoelectric element actuator according to an eighth embodiment of the present invention.

FIG. 19 is a diagram showing a relationship between the number of charging pulses and a high-frequency component value acquired by the pulse / high-frequency relationship acquisition section 71 in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power supply 1a Power supply voltage detection part 2,10 Switching transistor 3 Transformer 4,5 Diode 6,7,9 Resistance 8 Piezoelectric element 11,57,70 Control part 12 Memory 13 Voltage / pulse conversion table 14 Displacement / voltage conversion table 15 Relationship acquisition unit 16 Relationship monitoring unit 17 Power supply monitoring unit 18 Pulse frequency setting unit 20, 58 Drive circuit 21 Displacement input 50 Optical system 51 Image sensor 54 Signal processing circuit 59, 60 Piezoelectric actuator 71 Pulse / high frequency relationship acquisition unit 72 Charging Pulse number determination unit S1 Charge pulse S2 Charge voltage detection signal S3 Discharge pulse S4 Power supply voltage detection signal

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 41/08 U (54) [Title of the Invention] Drive device for piezoelectric element actuator, camera using this Patent application title: Method of driving a piezoelectric element actuator, method of focusing a camera using a driving device of a piezoelectric element actuator, and a computer-readable recording medium storing a program for causing a computer to execute the method

Claims (20)

[Claims] 1. A piezoelectric element actuator which applies a charging voltage corresponding to a charging pulse to a piezoelectric element in the piezoelectric element actuator to control a displacement amount of the piezoelectric element, and controls driving of the piezoelectric element actuator. In the driving device, charging means for energizing the piezoelectric element by applying the charging pulse to charge the piezoelectric element, and energizing the piezoelectric element by applying a discharging pulse to the piezoelectric element Discharging means for discharging the piezoelectric element, detecting means for detecting a charging voltage of the piezoelectric element, and applying the charging pulse to the piezoelectric element via the charging means after power is turned on and before the piezoelectric element is actually driven. Acquiring means for acquiring a relationship between the number of charging pulses during the charging and the charging voltage detected by the detecting means; and A conversion table that defines the relationship between the obtained number of charging pulses and the charging voltage; and, during actual driving of the piezoelectric element, the number of charging pulses corresponding to the amount of voltage corresponding to the amount of displacement of the piezoelectric element. A drive control unit that calculates by referring to the conversion table, and controls the drive of the piezoelectric element by applying a charging pulse of the calculated number of charging pulses via the charging unit. For driving piezoelectric element actuators. 2. The method according to claim 1, wherein the acquiring unit performs charging up to a maximum rated voltage of the piezoelectric element when acquiring the relationship between the number of charging pulses and a charging voltage, and performs a polarization process at the time of the acquisition. The driving device for a piezoelectric element actuator according to claim 1, wherein 3. The method according to claim 1, wherein the acquiring unit is configured to detect the charging voltage by the voltage detecting unit for each predetermined number of pulses when acquiring the relationship between the number of charging pulses and the charging voltage, and to determine the number of charging pulses. The driving device for a piezoelectric element actuator according to claim 1, wherein a relationship between the driving voltage and the charging voltage is obtained. 4. The acquiring unit, when acquiring the relationship between the number of charging pulses and the charging voltage, causes the voltage detecting unit to detect the charging voltage for each pulse, and acquires the number of charging pulses and the charging voltage. The driving device for a piezoelectric element actuator according to claim 1, wherein the relationship with the piezoelectric element actuator is obtained. 5. The acquisition means, when acquiring the relationship between the number of charging pulses and the charging voltage, changes a pulse frequency of the charging pulse and sets a pulse frequency that can be charged to a predetermined voltage at the highest speed. The drive control unit acquires, and the drive control unit performs drive control of the piezoelectric element based on the number of charging pulses having the pulse frequency acquired by the acquisition unit. A driving device for the piezoelectric element actuator according to any one of the preceding claims. 6. A method for monitoring whether or not a power supply voltage of a power supply for charging the piezoelectric element is within a predetermined allowable range, and when the power supply voltage is not within the predetermined allowable range, the number of charging pulses and a charging voltage. The power supply monitoring means for reacquiring the relationship between the number of charging pulses and the charging voltage stored in the conversion table and updating the relationship between the charging voltage and the charging voltage. A driving device for a piezoelectric element actuator according to any one of the first to third aspects. 7. A voltage immediately before discharging of the piezoelectric element is measured, and based on a relationship between a charging pulse number and a charging voltage stored in the conversion table, the measured voltage and a charging voltage at the time of the measurement are measured. Detecting whether the difference between the charging voltage and the charging voltage corresponding to the pulse number is within a predetermined range, and when the difference is not within the predetermined range, re-acquiring the relationship between the charging pulse number and the charging voltage; 7. The driving device for a piezoelectric element actuator according to claim 1, further comprising a relation monitoring unit that updates a relation between the number of charging pulses and the charging voltage stored in the storage unit. . 8. The method according to claim 1, wherein when the discharging of the piezoelectric element is performed, the acquiring unit causes the discharging of the piezoelectric element after charging the piezoelectric element to a maximum rated voltage. A driving device for the described piezoelectric element actuator. 9. A camera using the driving device for a piezoelectric element actuator according to claim 1. 10. A driving means for driving a focusing mechanism using a piezoelectric element, a charging means for energizing the piezoelectric element by applying a charging pulse to charge the piezoelectric element, and a discharging pulse. A discharge unit for causing the piezoelectric element to conduct electricity by applying the electric current to the piezoelectric element to discharge the piezoelectric element; a high-frequency component detection unit for detecting a high-frequency component of an image signal output from the imaging element; and driving the driving unit. Pulse number acquisition means for calculating the number of charging pulses when the high frequency component detected by the high frequency component detection means is the maximum during prescanning when performing focusing processing by using the piezoelectric element charged during the prescanning After discharging, the number of charging pulses acquired by the number-of-pulses acquiring means is applied to the piezoelectric element to perform actual driving for focusing. Camera comprising: the drive control means, the that. 11. The driving of a piezoelectric element actuator for controlling a displacement of the piezoelectric element by applying a charging voltage corresponding to a charging pulse to the piezoelectric element in the piezoelectric element actuator and controlling the driving of the piezoelectric element actuator. In the method, a holding step of holding a relationship between an input displacement amount and a charging voltage of the piezoelectric element in advance, and acquiring a relationship between a charging voltage of the piezoelectric element and the number of charging pulses after power-on and before actual driving of the piezoelectric element. Obtaining the charging voltage for the input displacement amount based on the relationship held in the holding step, obtaining the number of charging pulses for the obtained charging voltage from the relationship obtained in the obtaining step, A driving step of controlling the actual driving of the piezoelectric element by applying a charging pulse of the number of pulses for driving the piezoelectric element. 12. The method according to claim 1, wherein the obtaining step obtains a relationship between a charging voltage of the piezoelectric element and the number of charging pulses by charging up to a maximum rated voltage of the piezoelectric element, and performs a polarization process together. A method for driving a piezoelectric element actuator according to claim 11. 13. The method according to claim 1, wherein the acquiring step detects a charging voltage applied to the piezoelectric element for each predetermined number of pulses, and acquires a relationship between the charging voltage of the piezoelectric element and the number of charging pulses. A method for driving a piezoelectric element actuator according to claim 11. 14. The method according to claim 11, wherein in the obtaining step, a charging voltage applied to the piezoelectric element is detected for each pulse, and a relationship between the charging voltage of the piezoelectric element and the number of charging pulses is obtained. Or the driving method of the piezoelectric element actuator according to item 12. 15. The method according to claim 15, wherein the obtaining includes changing a pulse frequency of the piezoelectric element to determine a pulse frequency at which charging is performed at a maximum speed up to a predetermined voltage. A relationship acquisition step of acquiring a relationship between the charging voltage of the piezoelectric element and the number of charging pulses.
5. The driving method of the piezoelectric element actuator according to any one of 4. 16. A power supply voltage monitoring step of monitoring whether or not a power supply voltage of a power supply for charging the piezoelectric element is within a predetermined allowable range, and a power supply voltage is monitored within the predetermined allowable range by monitoring the power supply voltage monitoring step. If not, a reacquisition step of reacquiring the relationship between the number of charging pulses and the charging voltage,
The driving method of the piezoelectric element actuator according to claim 11, further comprising: 17. A voltage immediately before discharging of the piezoelectric element is measured, and based on a relationship between a charging pulse number and a charging voltage acquired in the acquiring step, the measured voltage and a charging voltage at the time of the measurement are measured. A relationship monitoring step of detecting whether a difference between the charging voltage and the charging voltage corresponding to the pulse number is within a predetermined range, and monitoring the relationship monitoring step. 17. The method of driving a piezoelectric element actuator according to claim 11, further comprising: a relationship reacquiring step of reacquiring a relationship between the voltage and the charging voltage. 18. The driving method for a piezoelectric element actuator according to claim 11, wherein in the obtaining step, the piezoelectric element is charged to a maximum rated voltage and then discharged. . 19. A pre-scan operation before driving a piezoelectric element actuator for driving a focusing mechanism, in which a charging pulse is applied to displace the piezoelectric element in the piezoelectric element actuator. An acquisition step of acquiring a relationship between a high-frequency component value of an image signal of a subject imaged via a focusing mechanism, and a relationship between the number of charging pulses and the high-frequency component value acquired by the acquisition step, A pulse number determining step of determining the number of charging pulses when the high-frequency component value is maximum; and charging the charging pulse number determined by the pulse number determining step after discharging the piezoelectric element charged during the prescan. A focusing step of applying a pulse for use to the piezoelectric element to perform focusing processing. A focusing method for a camera using a driving device for a piezoelectric element actuator. 20. A computer-readable recording medium on which a program for causing a computer to execute the method according to claim 11 is recorded.