JP2001246324A - Method for driving vibration actuator and drive assembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable more precise position control, etc., by making the step width of relative moving members, such as vibrators, and average relative speeds, nearly the same in forward driving and backward driving. SOLUTION: Drive signals consisting of burst waves are impressed to piezoelectric vibrators 12a and 12b of a vibration actuator 2. A drive parameter setting section 20 changes drive parameters, such as drive frequencies, in such a manner that the average relative speeds of the relative moving members driven by the vibration actuator 2 are made nearly the same when a moving speed control signal indicating the same speed is received in the forward driving and backward driving of the vibration actuator 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving method and a driving apparatus for a vibration actuator having an electromechanical transducer and applying a drive signal to the electromechanical transducer to generate vibration by generating vibration. More particularly, the present invention relates to a driving method and a driving device for applying a driving signal composed of a burst wave (intermittent wave) as the driving signal to the electromechanical transducer.

[0002]

2. Description of the Related Art Conventionally, as a driving method of a vibration actuator such as an ultrasonic motor, a driving method of applying a driving signal composed of a burst wave to an electromechanical transducer such as a piezoelectric element has been known.

According to this driving method, since a driving signal is intermittently applied to a piezoelectric element or the like, a small amount of a moving element as a driven object (relative moving member) driven by a vibration actuator can be driven. As a result, the average moving speed (macro moving speed) of the moving element can be reduced.
For this reason, according to the driving method using the driving signal composed of the burst wave, the positioning accuracy can be improved in, for example, position control using a vibration actuator.

In the conventional method of driving a vibration actuator using a drive signal composed of a burst wave, the same driving method is used when moving the moving element at the same speed during forward driving and reverse driving. It was driven according to the parameters.

[0005]

As a result of research conducted by the present inventor, as a result of the conventional method of driving a vibration actuator using a driving signal composed of a burst wave, driving is performed in accordance with the same driving parameters during forward driving and reverse driving. So
Originally, the step width and average speed of the mover should be the same, but in reality, the step width and average speed of the mover differ between forward drive and reverse drive. There was found. The reason for this is that the degree of friction between the driving force take-out part of the vibration actuator and the moving element and the effect of the asymmetry of the support of the vibration actuator cause the drive signal to rise and rise when driven by a burst signal. This is probably because the frequency of lowering is very high, and it appears remarkably.

As described above, in the conventional driving method, since the step width and the average speed of the moving element are different between the forward driving and the reverse driving, the positioning accuracy such as the position control is correspondingly different. Has been found by the present inventor. That is, for example, in order to stop the movable element at a desired target position, when the movable element reaches an allowable range with respect to the target position, the drive signal generation is stopped and the movable element is stopped by the self-holding torque. The movable element stops at a position shifted by a distance corresponding to the speed at which the movable element reaches the allowable range. At this time, if the conventional driving method is adopted,
Since the speed at which the mover moves from one direction and reaches the allowable range is different from the speed when the mover moves from the opposite direction and reaches the allowable range, the vibration actuator is driven in the forward direction. The positioning accuracy differs between the case where positioning is performed and the case where positioning is performed by driving in the opposite direction. Therefore, if the positioning accuracy during forward drive is increased, the positioning accuracy during reverse drive is reduced.
As a result, the positioning accuracy is reduced as a whole.

The present invention has been made in view of the above-mentioned problems of the conventional driving method found by the inventor, and has been described in connection with the steps of a relative moving member such as a moving member between forward driving and reverse driving. It is an object of the present invention to provide a driving method and a driving device for a vibration actuator that can make the width and the average relative speed substantially the same and can perform more precise position control and the like.

[0008]

According to a first aspect of the present invention, there is provided a method of driving a vibration actuator, comprising an electromechanical transducer, and applying a drive signal to the electromechanical transducer. In a method for driving a vibration actuator that obtains a driving force by generating vibrations, a driving signal composed of a burst wave is applied to the electromechanical transducer as the driving signal, and the vibration actuator is driven in a reverse direction when the vibration actuator is driven in a forward direction And at least one drive parameter is changed so that the average relative speed of the relative motion member driven by the vibration actuator is substantially the same.

In the driving method using a driving signal composed of a burst wave, the step width and the average relative speed of the relative moving member can be changed by changing the driving parameters. According to the first aspect, at least one drive parameter is changed between the time when the vibration actuator is driven in the forward direction and the time when the vibration actuator is driven in the reverse direction. The average relative speeds of the relative motion members are substantially the same. The fact that the average relative speeds of the relative motion members are substantially the same also means that the step widths of the relative motion members are substantially the same. According to the first aspect, since the step width and the average relative speed of the relative motion members can be made substantially the same as described above, the conventional driving method using a driving signal composed of a burst wave is more effective. Precise position control and the like can be performed.

A driving method for a vibration actuator according to a second aspect of the present invention has an electromechanical transducer, and obtains a driving force by generating a vibration by applying a drive signal to the electromechanical transducer. In the driving method, a driving signal composed of a burst wave is applied to the electromechanical transducer as the driving signal, and a moving speed control signal indicating the same speed during forward driving and reverse driving of the vibration actuator is generated. At least one driving parameter is changed so that when received, the average relative speed of the relative motion member driven by the vibration actuator is substantially the same.

In the first aspect, the relative speed of the relative movement member does not have to be constant and cannot be changed.
In the second aspect, it is assumed that the moving speed control signal is received so that the speed of the moving element can be changed. However, the same advantages as those of the first aspect can be obtained by the second aspect.

A method for driving a vibration actuator according to a third aspect of the present invention is the method according to the first or second aspect, wherein
The at least one drive parameter is a drive frequency,
It is one or more of the drive voltage level, the drive voltage phase difference, and the burst wave number.

In the third embodiment, examples of driving parameters are given, but the driving parameters in the first and second embodiments are not limited to these examples.

A driving apparatus for a vibration actuator according to a fourth aspect of the present invention has an electromechanical transducer, and applies a drive signal to the electromechanical transducer to generate vibration, thereby obtaining a driving force. In the driving device, the moving direction control signal is set so that the average relative speed of the relative motion member driven by the vibration actuator is substantially the same between when the vibration actuator is driven in the forward direction and when the vibration actuator is driven in the reverse direction. A drive parameter setting unit that sets at least one drive parameter in response to the drive signal, and a drive signal that outputs a drive signal including a burst wave as the drive signal according to the at least one drive parameter set by the drive parameter setting unit And a generation unit.

A driving apparatus for a vibration actuator according to a fifth aspect of the present invention has an electromechanical transducer, and obtains a driving force by generating a vibration by applying a drive signal to the electromechanical transducer. In the drive device, when a moving speed setting signal indicating the same speed is received when the vibration actuator is driven in the forward direction and when the vibration actuator is driven in the reverse direction, the average relative movement of the relative motion member driven by the vibration actuator A driving parameter setting unit that sets at least one driving parameter according to a movement direction control signal so that the speeds are substantially the same, and the driving parameter setting unit that sets the driving parameter according to the at least one driving parameter set by the driving parameter setting unit. A drive signal generation unit that outputs a drive signal composed of a burst wave as a drive signal.

According to a sixth aspect of the present invention, there is provided a driving device for a vibration actuator according to the fourth or fifth aspect, wherein
The at least one drive parameter is a drive frequency,
It is one or more of the drive voltage level, the drive voltage phase difference, and the burst wave number.

According to the fourth to sixth aspects, the driving methods according to the first to third aspects are realized, respectively.
The same advantages as those of the first to third aspects are obtained.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method and a device for driving a vibration actuator according to the present invention will be described with reference to the drawings.

[First Embodiment]

FIG. 1 is a block diagram showing a position control device using a driving device 1 according to a first embodiment of the present invention. FIG. 2 is a schematic perspective view showing an example of the vibration actuator 2 to be driven by the driving device 1 according to the present embodiment. FIG. 3 is a schematic perspective view showing the main body 10 of the vibration actuator 2 shown in FIG.

The main body 10 of the vibration actuator 2 is shown in FIG.
As shown in FIG. 3, an elastic body 11 made of metal or the like formed in a rectangular flat plate shape, and two piezoelectric elements 12a and 12b as electromechanical transducers joined to the upper surface of the elastic body 11 are provided. I have. The piezoelectric elements 12a and 12b are polarized in the thickness direction, and expand and contract in the plane direction when an AC voltage is applied in the thickness direction. The elastic body 11 is configured so that longitudinal vibration (first-order longitudinal vibration in this example) and bending vibration (fourth-order bending vibration in this example) are generated harmoniously by expansion and contraction of the piezoelectric elements 12a and 12b. (That is, they are designed such that their resonance frequencies are substantially equal). On the lower surface of the elastic body 11, protruding output extraction portions 11a and 11b are formed at portions that are antinodes of the fourth-order bending vibration, and the respective vibrations are generated in harmony, so that the output extraction portions 11a and 1b are formed.
Elliptic motion occurs in 1b. On both sides of the elastic body 11,
Notch portions 11c and 11d for support are formed.

As shown in FIG. 2, the vibration actuator 2 has a pin-like shape which engages with the notch 11c in addition to the main body 10 to regulate the position of the elastic body 11 with respect to the fixing portion (not shown). A pressing member (such as a spring) that presses the supporting members 14a and 14b and the main body 10 toward the relative motion member (moving element in the present embodiment) 15 to be driven (in the direction of arrow Z in FIG. 3). (Not shown), and guide rollers 16a and 16b for holding the relative motion member 15 from the side opposite to the main body 10. Since the output take-out portions 11a and 11b and the relative motion member 15 are in press contact with each other by the pressurization by the pressurizing member, a frictional force is generated between them. The relative movement member 15 is driven in the direction of arrow A (forward direction) or the direction of arrow B (reverse direction) in FIG. If the relative movement member 15 is fixed to the fixing portion instead of fixing the main body 10, the main body 10 moves.

The vibration actuator 2 of the present embodiment is configured to use vibration in the ultrasonic region, and functions as an ultrasonic motor. Also, as can be seen from the above description,
The vibration actuator 2 of this example is a linear type and a two-phase type. However, the vibration actuator to be driven by the driving device according to the present invention is not limited to the one described above, and may be a rotary type, the number of phases is not limited, and there is no need to use vibration in the ultrasonic region. .

The driving device 1 according to the present embodiment is similar to the driving device shown in FIG.
By applying a drive signal (drive voltage) composed of a burst wave as shown in FIG. 4A and a drive signal composed of a burst wave as shown in FIG. 4B to the piezoelectric elements 12a and 12b, respectively, Drive.

Here, the burst wave will be described with reference to FIG. 4. A sine wave AC voltage having a period T1 is generated during the ON time, and no voltage is generated during the OFF time (that is, 0 V). , ON time and OFF time are alternately and periodically continued. The reciprocal of the cycle T1 is the drive frequency.
The level V1 of the AC voltage generated during the ON time is the drive voltage level. The number of waves of the AC voltage generated during the ON time is a burst wave number. The product of the burst wave number and the period T1 is the ON time. The electrical phase difference Δθ between the AC voltage generated during the ON time in FIG. 4A and the AC voltage generated during the ON time in FIG. 4B is the phase difference of the drive voltage. Now, assuming that the phase of the drive voltage applied to the piezoelectric element 12a is 0 °, the phase of the drive voltage applied to the piezoelectric element 12b is + Δθ (for example, + 90 °) when the vibration actuator 2 is driven in the forward direction. At the time of reverse driving, the phase of the driving voltage applied to the piezoelectric element 12b is −Δθ (eg, −90 °). As a result, the direction of the elliptical motion is reversed, and driving in both forward and reverse directions is realized.

As shown in FIG. 1, the driving device 1 according to the present embodiment includes a piezoelectric element 12a of the vibration actuator 2 according to a moving direction control signal, a moving / stopping control signal, and a moving speed control signal given from the control unit 3. , 12b to drive the vibration actuator 2 by applying a drive signal (AC voltage) composed of the aforementioned burst wave.

The control unit 3 performs a movement / stop control signal based on a position detection signal from a position detector 4 such as an encoder for detecting the position of the relative movement member 15 and a target position signal input from the outside. The moving direction control signal and the moving speed control signal are provided to the driving device 1. That is, the control unit 3
The relative movement member 15 is determined based on the positional relationship between the current position and the target position.
Is calculated in the direction of the target position, and the direction is output as a movement control signal. When the relative movement member 15 is not located within a predetermined allowable range with respect to the target position, the control unit 3 outputs a movement / stop control signal indicating a movement command and is located within the allowable range. In case,
A movement / stop control signal indicating a stop command is output. Further, the control unit 3 outputs a movement / stop control signal instructing a fast speed according to the distance between the current position and the target position when the distance is long, and is slow when the distance is short. Outputs a movement / stop control signal that instructs speed. This is to increase the speed at a position far from the target position to shorten the moving time of the relative motion member 15 and to reduce the speed of the relative motion member 15 at a position near the target position to improve the positioning accuracy.

As shown in FIG. 1, the drive unit 1 includes a drive parameter setting unit 20, an oscillation circuit 21, a phase shift circuit 22
, A gate control signal generation circuit 23, and a gate circuit 24
a, 24b, filter circuits 25a, 25b, and amplifier circuits 26a, 26b.

The drive parameter setting unit 20 determines whether the average speed of the relative motion member 15 is equal to the average speed of the relative motion member 15 when receiving the moving speed setting signal indicating the same speed when the vibration actuator 2 is driven in the forward direction and when the vibration actuator 2 is driven in the reverse direction. A driving frequency, which is one of the driving parameters, is set according to the moving direction control signal so as to be substantially the same, and the driving frequency is supplied to the oscillation circuit 21 as a setting signal. In the present embodiment, the setting unit 20
Is composed of a microcomputer or the like and has a memory (not shown). In this memory, the driving frequency associated with the moving direction and the moving speed is stored in the reference table 20a.
Is stored in advance. Then, the setting unit 20
The driving frequency is set by referring to the reference table 20a according to the input moving direction control signal and moving speed control signal. The content of the reference table 20a is such that the average speed of the relative motion member 15 is substantially the same when a moving speed setting signal indicating the same speed is received at the time of forward drive and at the time of reverse drive. For example, the relationship between the drive frequency and the step width of the relative motion member 15 during forward drive and reverse drive can be determined by experiment and determined based on this. In the reference table 20a, not only the moving direction but also the moving speed is used as the parameter for determining the driving frequency to be set. This is because the same driving parameter is used for both the forward driving and the reverse driving. The difference in the moving speed between the forward drive and the reverse drive is
This is because when the moving speed changes, it comes differently.

When the movement / stop control signal indicates a movement command, the oscillation circuit 21 performs an oscillating operation and outputs a square wave pulse signal having a drive frequency indicated by the setting signal from the setting unit 20. On the other hand, when the movement / stop control signal indicates a stop command, the oscillation circuit 21 stops the oscillation operation and does not output a pulse. The square wave pulse signal generated by the oscillation circuit 21 is supplied to the gate circuit 24 as it is, and also supplied to the phase shift circuit 22 and the gate control signal generation circuit 23.

When the moving direction control signal indicates the positive direction, the phase shift circuit 22 outputs a square wave pulse signal whose phase is shifted by + 90 ° with respect to the square wave pulse signal generated by the oscillation circuit 20 to the gate circuit 24b. To supply. On the other hand, when the moving direction control signal indicates the reverse direction, the phase shift circuit 22 outputs the square wave pulse signal having a phase shifted by −90 ° with respect to the square wave pulse signal generated by the oscillation circuit 20 to the gate circuit 2.
4b.

The gate control signal generation circuit 23 generates a gate control signal indicating a period corresponding to the ON time in FIG. 4 by dividing the frequency of the square wave pulse signal generated by the oscillation circuit 20 or the like. The gate circuits 24a and 24b selectively pass, based on the gate control signal, only the square wave pulse of the supplied square wave pulse signal corresponding to the ON time in FIG. 25a, 2
5b.

The filter circuits 25a and 25b respectively filter the input square wave pulses and convert them into sine wave signals. The amplifier circuits 26a and 26b respectively amplify the signals output from the filter circuits 25a and 25b at an amplification factor according to the moving direction control signal, and output the signals as burst wave drive signals, respectively, and oscillate these drive signals. It is supplied to the piezoelectric elements 12a and 12b of the actuator 2, respectively. When the amplification factor of the amplifier circuits 26a and 26b increases (that is, the drive voltage level increases), the moving speed of the relative motion member 15 increases.

As can be understood from the above description, in the present embodiment, the elements 21, 22, 23, 24a, 24 in FIG.
b, 25a, 25b, 26a, 26b output a drive signal composed of a burst wave in accordance with the drive frequency, which is a drive parameter set by the setting unit 20, and apply the drive signal to the piezoelectric elements 12a, 12b. It constitutes a drive signal generator.

The elements 3, 20 to 23, 24 in FIG.
The functions a and 24b can be realized by a program using a single microcomputer.

According to the position control device shown in FIG. 1, the control unit 3 generates a movement / stop control signal, a movement direction control signal and a movement speed control signal based on a target position signal and a position detection signal from the position detector 4. The driving device 1 applies a driving signal composed of a burst wave to the piezoelectric elements 12a and 12b of the vibration actuator 2 based on these signals. Position control of the movement member 15 is performed.

At this time, the driving device 1 according to the present embodiment
In the above, the drive parameter, which is one of the drive parameters, is changed by the drive parameter setting unit 20 when the vibration actuator 2 is driven in the forward direction and when the vibration actuator 2 is driven in the reverse direction. For this reason, the average speed of the relative motion member 15 driven by the vibration actuator 2 is substantially the same between the forward drive and the reverse drive. Therefore, according to the present embodiment, more precise position control can be performed as compared with the conventional driving method using a driving signal composed of a burst wave.

Here, in Table 1 below, the drive frequency is changed among the drive parameters when the vibration actuator 2 is driven by a drive signal composed of a burst wave (hereinafter referred to as “burst drive”), and other parameters are changed. The experimental data of the step width of the relative motion member 15 at the time of forward drive and at the time of reverse drive obtained when the drive parameters are not changed are shown.
As can be seen from Table 1, the step width becomes smaller as the driving frequency becomes higher, and the step width becomes larger in the forward driving direction than in the reverse driving direction at all driving frequencies. In the case where such a vibration actuator 2 is used, the step width differs when the driving is performed in the normal and reverse directions at the same driving frequency. Different step widths result in different moving speeds.
However, data whose drive frequency is 0.2 KHz away (49.2 KHz in forward drive and 49.0 K in reverse drive)
Hz) are almost the same step width. Therefore, when driving in the forward direction at a frequency 0.2 KHz higher than that in the right direction driving, driving with substantially the same step width (hence, substantially the same speed) can be performed between the forward direction driving and the reverse direction driving. .

[0039]

[Table 1]

In the present embodiment, as can be seen from the above description, the drive frequency, which is one of the drive parameters, is changed only to equalize the speed in forward and reverse drive, and the drive parameter is changed. The drive voltage level, which is another one, is changed only in order to make the speed according to the moving speed control signal. However, in the present invention, for example, by changing one drive parameter, both the speed equalization in forward and reverse drive and the speed according to the movement speed control signal may be performed. . In this case, for example,
In FIG. 1, the moving speed control signal is supplied to amplifier circuits 26a and 26a.
6b, the drive voltage level is kept constant by keeping the amplification factors of the amplifier circuits 26a and 27a constant irrespective of the moving speed control signal. Then, the drive frequency in the reference table 20a of the drive parameter setting unit 20 may be determined so that the speed at the time of forward / reverse drive is equalized and the speed is in accordance with the moving speed control signal.

The driving device 1 according to the present embodiment is
The moving speed control signal is received from the control unit 3. However, the relative movement member 1 always has a constant average speed.
5 may be moved to control the position. In this case, for example, in FIG. 1, if the line of the moving speed control signal is removed, the amplification factors of the amplifier circuits 26a and 27a are fixed, and the contents of the look-up table 20a are the driving frequencies associated only with the moving direction. Good.

[Second Embodiment]

Although not shown in the drawings, the second embodiment of the present invention is a modification of the first embodiment as follows.

In the first embodiment, the drive frequency is used as a drive parameter to be changed in order to equalize the speed at the time of forward / reverse drive, but in the present embodiment, the drive parameter is used as the drive parameter. Use voltage levels. Specifically, for example, in FIG. 1, the setting signal from the drive parameter setting unit 20 is input not to the oscillation circuit 21 but to the amplification circuits 26a and 26b, and the moving speed control signal is output to the oscillation circuit 21 instead of the amplification circuits 26a and 26b. Input. The content of the reference table 20a is such that the average speed of the relative motion member 15 is substantially the same when the moving speed setting signal indicating the same speed is received in the forward drive and the reverse drive. The driving voltage level (amplifying circuits 26a, 26b)
).

According to this embodiment, advantages similar to those of the first embodiment can be obtained.

Table 2 below shows, in the driving parameters for the burst driving, the driving voltage level is changed and the other driving parameters are not changed. The driving parameters for the forward driving and the reverse driving are obtained. Experimental data of the step width of the relative motion member 15 is shown. As can be seen from Table 2, the drive voltage level and the step width have a substantially linear relationship.
When the driving voltage level increases by 5 V, the step width becomes approximately 0.4.
μm increase. Therefore, when driving in the reverse direction at a drive voltage level that is about 7.5 V higher than that in the forward direction drive, substantially the same step width (and thus substantially the same speed) is obtained between the forward direction drive and the reverse direction drive. Can be driven.

[0047]

[Table 2]

[Third Embodiment]

Although not shown in the drawings, the third embodiment of the present invention is a modification of the first embodiment as follows.

In the first embodiment, the drive frequency is used as the drive parameter to be changed in order to equalize the speed in the forward and reverse drive, but in the present embodiment, the drive parameter is used as the drive parameter. The voltage phase difference is used. Specifically, for example, in FIG. 1, the setting signal from the drive parameter setting unit 20 is input not to the oscillation circuit 21 but to the phase shift circuit 22. The oscillation circuit 21 is configured to always output a square wave pulse signal having a constant drive frequency. Further, the phase shift circuit 22 calculates the phase difference Δθ of the drive voltage indicated by the setting signal from the drive parameter setting unit 20.
According to, when the moving direction control signal indicates the forward direction,
A square wave pulse signal whose phase is shifted by + Δθ with respect to the square wave pulse signal generated by the oscillation circuit 20 is transmitted to the gate circuit 2.
4b, and when the movement direction control signal indicates the reverse direction, a square wave pulse signal whose phase is shifted by -Δθ with respect to the square wave pulse signal generated by the oscillation circuit 20 is supplied to the gate circuit 24b. The configuration is as follows. The content of the reference table 20a is such that the average speed of the relative motion member 15 is substantially the same when the moving speed setting signal indicating the same speed is received in the forward drive and the reverse drive. , The phase difference of the driving voltage associated with the moving direction and the moving speed.

According to this embodiment, the same advantages as those of the first embodiment can be obtained.

Here, in Table 3 below, of the drive parameters at the time of the burst drive, the phase difference of the drive voltage is changed.
The experimental data of the step width of the relative movement member 15 at the time of forward drive and at the time of reverse drive obtained without changing other drive parameters are shown. As can be seen from Table 3, the step width is maximum when the phase difference of the drive voltage is 90 ° in both forward and reverse driving. However, in the case of the same phase, for example, when the phase difference is 90 °, the step width is 3.0 μm in the forward drive, and 2.8 μm in the reverse drive. Yes,
The step width differs between the forward drive and the reverse drive. Therefore, the phase difference of the drive voltage during the forward drive is 80
{Circle around (2)} If the phase difference between the driving voltages in the reverse driving is 90 °, the driving can be performed with substantially the same step width (and, consequently, substantially the same speed) in the forward driving and the reverse driving.

[0053]

[Table 3]

[Fourth Embodiment]

Although not shown in the drawings, the fourth embodiment of the present invention is a modification of the first embodiment as follows.

In the first embodiment, the drive frequency is used as the drive parameter to be changed in order to equalize the speed at the time of forward / reverse drive, but in the present embodiment, the drive parameter is a burst parameter as the drive parameter. Use the wave number.
Specifically, for example, in FIG. 1, the setting signal from the drive parameter setting unit 20 is input not to the oscillation circuit 21 but to the gate control signal generation circuit 23. The oscillation circuit 21
It is configured to always output a square wave pulse signal having a constant driving frequency. Further, the gate control signal generation circuit 23 is configured to output a gate control signal that causes a pulse of the wave number to pass through the gate circuits 24a and 24b in accordance with the burst wave number indicated by the setting signal from the drive parameter setting unit 20. Keep it. The content of the reference table 20a is different between when driving in the forward direction and when driving in the reverse direction.
When a moving speed setting signal indicating the same speed is received, a burst wave number associated with the moving direction and the moving speed is set so that the average speed of the relative motion member 15 is substantially the same.

According to this embodiment, advantages similar to those of the first embodiment can be obtained.

Table 4 below shows relative driving parameters during forward driving and reverse driving obtained when the burst wave number is changed and other driving parameters are not changed among the driving parameters during burst driving. Experimental data of the step width of the moving member 15 is shown. In this experiment, since the driving frequency was set to 50 KHz, for example, a burst wave number of 10 means that the ON time is 0.2 mS (millisecond). As can be seen from Table 4, when driving in either the forward or reverse direction, the more burst waves, the larger the step width. However, when the number of burst waves is the same, for example, when the number of burst waves is 20, the step width in forward drive is 1.0 μm, while the step width in reverse drive is 0.8 μm. The step width is different between the forward drive and the reverse drive.
Therefore, if the burst wave number at the time of forward driving is 20 and the burst wave number at the time of reverse driving is 25, almost the same step width (and thus almost the same speed) between the forward driving and the reverse driving. Can be driven.

[0059]

[Table 4]

The embodiments of the present invention have been described above, but the present invention is not limited to these embodiments. For example, in each of the above-described embodiments, one drive parameter is changed to equalize the speed at the time of forward / reverse drive, but a plurality of drive parameters are changed to equalize the speed at the time of forward / reverse drive. The parameters may be changed.

In the above description, an example has been given in which the driving device according to the present invention is used in a position control device. However, it goes without saying that the driving device according to the present invention can be used in other applications.

[0062]

As described above, according to the present invention,
The step width and the average relative speed of the relative moving member such as the moving element can be made substantially the same between the forward drive and the reverse drive. As a result, more precise position control and the like can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a position control device using a driving device 1 according to a first embodiment of the present invention.

FIG. 2 is a schematic perspective view showing an example of a vibration actuator to be driven by the driving device according to the present embodiment.

FIG. 3 is a schematic perspective view showing a main body of the vibration actuator shown in FIG. 2;

FIG. 4 is a waveform diagram showing a drive signal based on a burst wave.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Drive device 2 Vibration actuator 3 Control part 4 Position detector 12a, 12b Piezoelectric element 20 Drive parameter setting part 20a Lookup table 21 Oscillation circuit 22 Phase shift circuit 23 Gate control signal generation circuit 24a, 24b Gate circuit 25a, 25b Filter circuit 26a , 26b Amplifier circuit

Claims (6)

[Claims] 1. A driving method for a vibration actuator having an electromechanical transducer, wherein a driving signal is applied to the electromechanical transducer to generate a driving force by generating vibration, the driving signal comprises a burst wave. A drive signal is applied to the electromechanical transducer, so that the average relative speed of the relative motion member driven by the vibration actuator is substantially the same between when the vibration actuator is driven in the forward direction and when the vibration actuator is driven in the reverse direction. And at least one drive parameter is changed. 2. A method for driving a vibration actuator having an electromechanical transducer, wherein a drive signal is applied to the electromechanical transducer to generate a vibration by generating a vibration, wherein the drive signal comprises a burst wave. When a driving signal is applied to the electromechanical transducer, and a moving speed control signal indicating the same speed is received during forward driving and reverse driving of the vibration actuator, a relative drive driven by the vibration actuator is performed. A method for driving a vibration actuator, characterized in that at least one drive parameter is changed so that the average relative speed of the moving members is substantially the same. 3. The at least one drive parameter includes a drive frequency, a drive voltage level, a phase difference between drive voltages,
3. The driving method for a vibration actuator according to claim 1, wherein the number is at least one of burst wave numbers. 4. A driving apparatus for a vibration actuator, comprising: an electromechanical transducer, wherein a driving signal is applied to the electromechanical transducer to generate a vibration by generating a vibration. Drive parameter setting for setting at least one drive parameter in accordance with the movement direction control signal so that the average relative speed of the relative motion member driven by the vibration actuator is substantially the same between and during the reverse drive. A drive signal generating unit that outputs a drive signal composed of a burst wave as the drive signal according to the at least one drive parameter set by the drive parameter setting unit. Actuator drive. 5. A driving device for a vibration actuator, comprising: an electromechanical transducer, wherein a driving signal is applied to the electromechanical transducer to generate a vibration by generating a vibration. When the moving speed setting signal indicating the same speed is received during the reverse driving and during the reverse driving, the moving direction control signal is set so that the average relative speed of the relative moving member driven by the vibration actuator is substantially the same. A drive parameter setting unit that sets at least one drive parameter according to the following: a drive that outputs a drive signal including a burst wave as the drive signal according to the at least one drive parameter set by the drive parameter setting unit A driving device for a vibration actuator, comprising: a signal generation unit. 6. The at least one driving parameter includes a driving frequency, a driving voltage level, a phase difference between driving voltages,
The driving device for a vibration actuator according to claim 4, wherein the driving frequency is at least one of burst wave numbers.