JP2000078861A - Drive circuit suitable for actuator using electromechanical transducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the driving circuit of an actuator which can position the actuator accurately taking the resonance frequency of a driving system into account and uses an electromechanical transducer. SOLUTION: A CPU 20 calculates the transfer distance of a slider 14 in accordance with a target position signal and the present position signal of the slider 14 and, in accordance with the transfer distance, drives a rough movement driving circuit 22 or a fine movement driving circuit 23 to operate. A variable frequency band blocking filter circuit 24 is inserted into the post stage of the fine movement driving circuit 23, and a central frequency band which attenuates a gain is changed to be higher or lower accordance with the position signal of the slider 14 which is outputted form a signal processing circuit 21. With this constitution, the resonance point of the natural frequency of a driving system which fluctuates in accordance with the position of the slider 14 on a driving shaft is shifted from the cross-over frequency of a servo-system to suppress the oscillation of the servo-system, so that an actuator can be driven with high positioning precision.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator driving circuit using an electromechanical transducer, and more particularly to an XY moving stage for precise measurement, a photographing lens of a camera, and projection of an over head projector. Actie using electromechanical transducers used for lenses, binocular lenses, etc.
The present invention relates to a driving circuit suitable for driving a motor.

[0002]

2. Description of the Related Art When a driving pulse having a waveform composed of a gentle rising portion and a rapid falling portion following the same is applied to an electromechanical transducer, for example, a piezoelectric element, the piezoelectric element gradually becomes gentle at the gentle rising portion of the driving pulse. An elongation displacement occurs in the thickness direction, and a contraction displacement occurs rapidly at a rapid falling portion. Therefore, utilizing this characteristic, a drive pulse having the above-described waveform is applied to the piezoelectric element to repeatedly charge and discharge at different speeds, thereby causing the piezoelectric element to vibrate in the thickness direction at different speeds, thereby causing the piezoelectric element to vibrate. 2. Description of the Related Art An actuator is known which reciprocates a fixed driving member at different speeds and moves a moving member frictionally coupled to the driving member in a predetermined direction.

FIGS. 7 and 8 show an example of an actuator using the above-described electromechanical transducer. FIG. 7 shows an actuator.
FIG. 8 is a perspective view showing a disassembled state, and FIG. 8 is a perspective view showing an assembled state.

Referring to FIGS. 7 and 8, an actuator 10
0 denotes a fixed member 101, a piezoelectric element 110, a drive shaft 11
1, the slider 112, and other members.

The fixing member 101 has a substantially cylindrical shape as a whole, and has a first hole 102 and a second hole 103 penetrating in a diametrical direction (vertical direction in FIG. 7).
A bearing 104a for supporting the drive shaft 111 is formed in the wall 104 between the first and third walls. In addition, a portion of the end surface of the fixing member 101 which forms the wall portion 105 of the hole 103 includes:
A bearing 105a for supporting the drive shaft 111 is formed. The portion 106 of the fixing member is a mounting portion for mounting the actuator to the device.

A piezoelectric element 110 is disposed in the first hole 102, and one end of the piezoelectric element 110 is fixed to the wall surface of the fixing member 101 on the side of the mounting portion 106 by bonding.
A drive shaft 111 is fixed to the other end of the device 10 by bonding. The drive shaft 111 includes a bearing 104 a of the wall 104 and the wall 1.
When the piezoelectric element 110 undergoes expansion and contraction displacement in the thickness direction, the piezoelectric element 1
The drive shaft 111 bonded and fixed to 10 can reciprocate in the axial direction.

Reference numeral 112 denotes a slider, which is disposed in the hole 103 of the fixing member 101, and is configured so that the inside of the hole 103 can be moved in the axial direction of the cylinder 103 by using a longitudinal inner wall surface of the hole 103 as a rotation stopper and a guide. Have been. Below the slider 112, there is provided a mounting portion 112c for mounting a member driven by the actuator 100, for example, a movable lens barrel in the case of a lens device.

The drive shaft 111 penetrates through a hole 112a formed in the main body of the slider 112.
An opening 112b is formed in the upper portion through which the drive shaft 111 penetrates, and the upper half of the drive shaft 111 is exposed. A pad 1 that contacts the upper half of the drive shaft 111 is provided in the opening 112b.
13 is inserted and the pad 113 has a projection 1 on its upper part.
13a, a groove 1 on the lower surface that contacts the upper half of the drive shaft 111
13b is provided. Projection 113a of pad 113
Is pressed down by the leaf spring 114, the groove 113b of the pad 113 comes into contact with the drive shaft 111, and a downward urging force F is applied. Note that 115 is a leaf spring 114
To fix the slider to the slider 112. Also,
Although not shown, a moving member, for example, a lens barrel is fixed to the slider 112.

With this configuration, the drive shaft 111 and the pad 1
The slider 13 and the slider 112 are friction-coupled with an appropriate friction coupling force. Adjustment of the urging force F that determines the frictional coupling force is performed by using the screw 1
15 can be adjusted by adjusting the tightening.

As described above, the drive shaft 111 is mounted on the wall 1
04 is supported by a bearing 104a of the wall 104 and a bearing 105a of the wall 105, and the end 1 opposite to the piezoelectric element 110 side.
11a slightly protrudes from the hole of the bearing 105a.

A leaf spring 117 is fixed to the outside of the wall 104 by screws 118.
1a is pressed in the axial direction. The pressing force can be adjusted by adjusting the tightening and tightening of the screw 118.

Next, the operation will be described. First, when a saw-tooth wave driving pulse having a gentle rising portion and a rapid falling portion as shown in FIG. 9A is applied to the piezoelectric element 110, the piezoelectric element 110 becomes The piezoelectric element 1 is gradually extended in the thickness direction and displaced.
The drive shaft 111 coupled to 10 also gently displaces in the forward direction (the direction of arrow a). At this time, the slider 112 frictionally coupled to the drive shaft 111 moves in the forward direction together with the drive shaft 111 due to the friction coupling force.

In the rapid falling portion of the driving pulse, the piezoelectric element 110 is rapidly contracted and displaced in the thickness direction.
The drive shaft 111 connected to 10 is also rapidly displaced in the negative direction (the direction opposite to the arrow a). At this time, the slider 112 frictionally coupled to the drive shaft 111 overcomes the frictional coupling force due to the inertial force and substantially stays at that position and does not move. By continuously applying the drive pulse to the piezoelectric element 110, reciprocating vibrations having different speeds are generated on the drive shaft 111,
The slider 112 frictionally coupled to the drive shaft 111 can be continuously moved in the positive direction.

[0014] The term "substantially" as used herein means that the frictional coupling surface between the slider 112 and the drive shaft 111 follows and slides in both the forward direction and the opposite direction.
There is also included one that moves in the direction of arrow a as a whole due to the difference in driving time.

In order to move the slider 112 in the opposite direction (the direction opposite to the arrow a), the waveform of the sawtooth-wave drive pulse applied to the piezoelectric element 110 is changed, and the speed is changed as shown in FIG. This can be achieved by applying a drive pulse composed of a gentle rising portion and a gentle falling portion.

The above-described driving by the sawtooth wave driving pulse is a driving mode for moving the slider, that is, the moving member at a desired position at a high speed, and is hereinafter referred to as a coarse movement mode. In such an actuator, in order to precisely position the slider, that is, the moving member, at a desired position, in addition to the coarse movement mode described above, a predetermined voltage is applied to the piezoelectric element to extend or shrink. There is proposed a driving means which includes a fine movement mode for generating the convergence, and operates by switching appropriately.

FIG. 10 is a block diagram of an actuator driving circuit capable of switching between the coarse movement mode and the fine movement mode. In FIG. 10, the actuator 100 is shown in FIG.
FIG. 8 shows a main part of the configuration shown in FIG. 8, and the same members are denoted by the same reference numerals. That is, 101 is a fixing member, 11
0 denotes a piezoelectric element, 111 denotes a drive shaft, and 112 denotes a slider. The slider 112 is provided with a known position sensor 126 for detecting a current position with respect to a reference position (for example, an end of a fixed member). As the position sensor, a known MR sensor including a magnetic rod magnetized at a fixed interval and a magnetoresistive element can be used.

The driving circuit includes a CPU 120, a CPU 120
, A signal processing circuit 121 connected to the input port, a coarse drive circuit 122 connected to the output port, and a fine drive circuit 1.
23, a switching switch 124 for switching between a coarse movement mode and a fine movement mode, and a voltage amplifier circuit 125. The switching switch 124 is switched by a switching signal output from the CPU 120.

Slider 1 detected by position sensor 126
12 is processed by the signal processing circuit 121 and
A drive signal input to the PU 120 and output from the voltage amplification circuit 125 is configured to be applied to the piezoelectric element 110. In addition, although illustration is omitted,
The input port of the CPU 120 is configured to receive a signal indicating the slider 112, that is, a target position of the moving body, from a keyboard or other input device (not shown).

Next, the operation will be described. Slider 11
2 is input to CPU 120, CP
In U 120, the target position signal and the slider 112 detected by the position sensor 126 and processed by the signal processing circuit 121.
, The moving distance of the slider 112, that is, the moving distance is calculated.

When the CPU 120 determines that high-speed movement is necessary based on the calculated movement distance, the CPU 120 switches the switching switch 124 to the coarse movement mode,
22 is operated to generate a saw-tooth wave driving pulse, which is applied to the piezoelectric element 110 via the voltage amplifying circuit 125. The piezoelectric element 110 undergoes expansion and contraction displacement in the thickness direction, and the drive shaft 11
1 generate reciprocating vibrations having different speeds, and continuously move the slider 112 frictionally coupled to the drive shaft 111 in a predetermined direction.

The position of the slider 112 is determined by a position sensor 126.
Are detected continuously. When the slider 112 approaches the target position and its position signal is input to the CPU 120, and it is detected that the slider 112 has approached within a predetermined distance, the CPU 12
0, the switching switch 124 is switched to the fine movement mode side, and the fine movement drive circuit 123 is operated to operate the slider 112.
A drive signal of a predetermined voltage corresponding to the difference between the target position and the current position of the piezoelectric element 1 is generated through the voltage amplifying circuit 125.
10 is applied. The piezoelectric element 110 is displaced in the thickness direction according to the voltage of the drive signal, and moves the slider 112 to the target position. In the fine movement control, servo control is performed in which the position signal of the slider 112 is fed back to the drive signal and the slider is set at a predetermined position.

[0023]

In the positioning control of an actuator using a piezoelectric element, it is necessary to consider the natural vibration of the driving system including the piezoelectric element, the drive shaft and the slider. In the transfer characteristic up to the behavior described above, there is a resonance point where mechanical resonance occurs in a high frequency region due to the compliance of the drive system including the piezoelectric element, the drive shaft, and the slider.

In the fine movement mode, the crossover frequency of the servo system for performing the fine movement control is set to be high in order to realize highly accurate positioning. If the frequency is close to the bar frequency, the servo system easily oscillates, and the positioning accuracy of the slider deteriorates.

Further, the above-mentioned resonance frequency varies depending on the position on the drive shaft of the slider. For example, when the slider is located close to the piezoelectric element, the resonance frequency increases,
When it is at a far position, the resonance frequency becomes low. For this reason, even if an attempt is made to suppress the resonance of the drive system using a means for lowering the gain for a specific frequency, the resonance frequency fluctuates depending on the position on the drive shaft of the slider. In this case as well, there is a disadvantage that the positioning accuracy of the slider, that is, the moving body is deteriorated.

[0026]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and an invention according to claim 1 is an electromechanical transducer, and a drive which is fixedly connected to the electromechanical transducer and is displaced together with the electromechanical transducer. A drive circuit for an actuator using an electromechanical transducer having a member and a moving member frictionally coupled to the drive member, the drive circuit comprising: a position detector for detecting a position of the moving member; A drive signal generating circuit for generating a drive signal for causing a displacement in the electromechanical transducer, and a center frequency that is inserted on an output side of the drive signal generating circuit and changes a center frequency based on a position signal output from the position detector A center frequency variable band rejection filter circuit having a means for performing the operation, a position signal output from the position detector being fed back to a drive signal generation circuit to control the drive signal, and Characterized in that it comprises a drive control means for setting in place.

The means for changing the center frequency of the band rejection filter circuit sets the center frequency high when the moving member frictionally coupled to the driving member is closer to the electromechanical transducer, and The center frequency is set to be low when it is far from the electromechanical transducer.

Further, the means for changing the center frequency of the band rejection filter circuit may be a circuit including a semiconductor element for changing the center frequency by controlling the gate voltage with the position signal.

Further, the means for changing the center frequency of the band rejection filter circuit may be a circuit for changing the center frequency by multiplying the driving signal and the position signal by a multiplying circuit.

According to a fifth aspect of the present invention, there is provided an electromechanical transducer,
A drive circuit for an actuator using an electromechanical transducer having a drive member fixedly coupled to the electromechanical transducer and displaced together with the electromechanical transducer, and a moving member frictionally coupled to the drive member, The drive circuit includes a position detector that detects a position of the moving member, and a reciprocating vibration having different speeds generated in the drive member by continuously generating expansion and contraction displacement in the electromechanical transducer, and frictionally coupled to the drive member. A first drive signal generating circuit for generating a drive signal of a first mode for moving the moving member at high speed, a driving member for generating a displacement in the electromechanical transducer, and a moving member frictionally coupled to the driving member. A second drive signal generating circuit for generating a drive signal of a second mode for moving the drive, a mode switching means for switching between the first mode and the second mode, and a second drive signal generation. Insert at the output side of the circuit A center frequency variable band rejection filter circuit having means for changing a center frequency based on the position signal output from the position detector, and a first mode based on the position signal output from the position detector. Drive control means for controlling the drive signals of the first and second modes and setting the movable member at a predetermined position.

The first drive signal generating circuit may be a sawtooth drive pulse generating circuit.

[0032]

Embodiments of the present invention will be described below. FIG. 1 is a block diagram of an actuator driving circuit according to an embodiment of the present invention. The actuator driving circuit has a configuration similar to the configuration described above with reference to FIG. 10, and differs in that a variable frequency band rejection filter circuit is inserted at the subsequent stage of the fine movement driving circuit.

In FIG. 1, reference numeral 10 denotes the entire actuator. Reference numeral 11 denotes a fixed member, 12 denotes a piezoelectric element which is one of electromechanical transducers, 13 denotes a driving member, that is, a driving shaft, and 14 denotes a moving member that moves on the driving shaft, ie, a slider. The slider 14 has a reference position (for example, an end of a fixed member).
A known position sensor 1 for detecting the current position with respect to
5 are provided. As a position sensor, a well-known MR comprising a magnetic rod magnetized at regular intervals and a magnetoresistive element is used.
A sensor or the like can be used. In addition, a moving member,
That is, a member to be driven, for example, a lens barrel is attached to the slider when this actuator is applied to a lens device.

The drive circuit is provided at the subsequent stage of the CPU 20, a signal processing circuit 21 connected to the input port of the CPU 20, a coarse drive circuit 22, a fine drive circuit 23, and a fine drive circuit 23 connected to the output port. It comprises an inserted variable frequency band rejection filter circuit 24, a switching switch 25 for switching between a coarse movement mode and a fine movement mode, and a voltage amplifier circuit 26.

The switching switch 25 is switched by a switching signal output from the CPU 20. Position sensor 15
The position signal of the slider 14 detected by the signal processing circuit 21 is processed by the signal processing circuit 21 and then input to the CPU 20, and the drive signal output from the voltage amplification circuit 26 is
Is configured to be applied. Further, the variable frequency band rejection filter circuit 24 is configured to receive the signal indicating the position of the slider output from the signal processing circuit 21 and change the center frequency of the band rejection filter according to the position of the slider. The configuration of the band rejection filter will be described later in detail.

Although not shown, the CPU
A signal indicating the target position of the moving member, i.e., the slider, is input to an input port 20 from a keyboard or other input device (not shown).

Next, the operation will be described. Slider 14
Is input to the CPU 20, the CPU 2
In the case of 0, the moving distance of the slider 14, that is, the moving distance, is calculated based on the target position signal and the current position signal of the slider 14 detected by the position sensor 15 and processed by the signal processing circuit 21.

When the CPU 20 determines that high-speed movement is necessary based on the calculated movement distance, the switching switch 2
5 is switched to a coarse mode as a first mode, and a coarse drive circuit 22 for generating a drive signal of the first mode is operated to generate a sawtooth drive pulse, thereby generating a voltage amplifying circuit. 2
6 and is applied to the piezoelectric element 12. The piezoelectric element 12 undergoes expansion and contraction displacement in the thickness direction to generate reciprocating vibrations at different speeds on the drive shaft 13, thereby continuously moving the slider 14 frictionally coupled to the drive shaft 13 in a predetermined direction.

The position of the slider 14 is continuously detected by the position sensor 15. When the slider 14 approaches the target position and the position signal is input to the CPU 20 and it is detected that the slider 14 has approached within a predetermined distance, the CPU 20 sets the switching switch 25 to the fine movement mode which is the second mode. In addition to the switching, the fine drive circuit 23 for generating the second mode drive signal is operated to generate a drive signal of a predetermined voltage corresponding to the difference between the target position and the current position of the slider 14, thereby preventing the variable frequency band. Filter circuit 24 and voltage amplifier circuit 26
Is applied to the piezoelectric element 12.

The piezoelectric element 12 is displaced in the thickness direction in accordance with the voltage of the second mode drive signal, and moves the slider 14 to the target position.

In the above control, servo control is performed in which the position signal of the slider 14 is fed back to the drive signal and the slider is set at a predetermined position.

The variable frequency band rejection filter circuit 24 includes:
This filter circuit attenuates the gain at the resonance frequency sharply with respect to the drive signal output from the fine movement drive circuit 23, and attenuates the gain by the position signal of the slider 14 output from the signal processing circuit 21. The center frequency band can be varied higher or lower.

FIGS. 2A and 2B show the relationship between the distance of the slider 14 from the reference position and the open loop transmission characteristics of the servo control system in the fine movement mode as the second mode. FIG.

First, FIG. 2A is a diagram for explaining the displacement of the slider 14 from the reference position. Here, the reference position is the end of the fixed member 11. The slider when the slider 14 is located at a position (x) from the reference position (position close to the piezoelectric element 12) is denoted by reference numeral 14 (x),
The slider at the position (y) (a position far from the piezoelectric element 12) is indicated by reference numeral 14 (y).

FIG. 2B is a diagram showing the open loop transmission characteristic of the servo control system in the fine movement mode as the second mode, in which the slider 14 is at a distance (x) from the reference position. (The position close to the piezoelectric element 12), the transfer characteristic is indicated by a solid line.
(x), and when the slider 14 is located at a distance (y) from the reference position (a position far from the piezoelectric element 12), the transfer characteristic exhibits a characteristic as indicated by a dotted line (y). . That is, when the slider 14 is close to the reference position, the resonance frequency is high, and when the slider 14 is far from the reference position, the mechanical resonance frequency is low, and the resonance frequency changes Δf depending on the position of the slider.

FIG. 3 is a simulation circuit diagram of a variable frequency band rejection filter circuit, and FIG. 4 is a frequency characteristic diagram showing a result of the simulation. In FIG. 3, the variable resistor R8 on the input side is set to 100Ω, 300Ω, 1 kΩ,
When kΩ and 10 kΩ are changed, the frequency characteristics of this circuit are as shown in FIG. 4. By changing the resistance value, the center frequency of the gain attenuated by the band rejection filter circuit can be changed to be higher or lower. Understand.

FIG. 5 is a diagram showing an example of a specific circuit of the variable frequency band rejection filter circuit. The input IN indicates a voltage signal input from the fine drive circuit 23, and the external input EX.
T indicates a position signal of the slider 14 input from the signal processing circuit 21. Reference numeral 31 denotes a field effect transistor.

Since the resistance between the drain D and the source S of the field effect transistor 31 has a linear characteristic that changes in accordance with the voltage input to the gate G, the variable resistance R8 of the circuit shown in FIG. It can be used as a function corresponding to. That is, by inputting the position signal of the slider 14 to the gate G of the field effect transistor 31, the center frequency of the band rejection filter circuit can be changed according to the position of the slider 14. By passing the voltage signal IN input from the fine movement drive circuit 23 through a band rejection filter circuit that changes according to the position of the slider 14, the resonance of the actuator that changes according to the position of the slider 14 is effectively reduced. Can be suppressed.

FIG. 6 is a diagram showing another specific example of the variable frequency band rejection filter circuit. The input IN indicates a voltage signal input from the fine movement driving circuit 23, and the external input E
XT is the slider 14 input from the signal processing circuit 21.
3 shows a position signal of the first embodiment. Reference numeral 32 denotes a multiplier.

By multiplying the voltage signal IN input from the fine movement drive circuit 23 by a position signal indicating the position of the slider 14, the center frequency of the band rejection filter circuit is changed corresponding to the position of the slider 14. Can be.

The variable frequency band rejection filter circuit shown in FIG. 5 can be constructed at a low cost, and the filter circuit shown in FIG. 6 uses a commercially available temperature-compensated multiplier to reduce the frequency of the filter circuit. The frequency can be set with high accuracy.

In the embodiment of the present invention described above, an example is described in which a piezoelectric element is used as an electromechanical transducer. However, the present invention is applicable to other electromechanical transducers, for example, actuators utilizing electromagnetic force. Similarly, the present invention can be applied to a driving circuit of a computer.

[0053]

As described above, in the drive circuit of the present invention, in the second mode, that is, in the fine movement mode, the center frequency is output to the output side of the drive signal generation circuit based on the position signal of the moving member. The center frequency is changed according to the position of the moving member, and the center frequency is changed according to the position of the moving member. The resonance point of the vibration can be shifted from the crossover frequency range of the servo system, the oscillation of the servo system for performing the fine movement control can be suppressed, and the actuator can be driven with high positioning accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram of an actuator driving circuit according to an embodiment of the present invention.

FIG. 2 is a view for explaining a relationship between a distance of a slider from a reference position and an open loop transmission characteristic of a servo control system in a second mode (fine movement mode).

FIG. 3 is a simulation of a variable frequency band rejection filter circuit.
Circuit diagram

FIG. 4 is a frequency characteristic diagram showing a simulation result of the filter circuit shown in FIG. 3;

FIG. 5 is a circuit diagram showing an example of a specific example of a variable frequency band rejection filter circuit.

FIG. 6 is a circuit diagram showing another specific example of the variable frequency band rejection filter circuit.

FIG. 7 is a perspective view showing an exploded state of an actuator using the electromechanical transducer.

FIG. 8 is a perspective view showing an assembled state of the actuator shown in FIG. 7;

FIG. 9 illustrates a waveform of a driving pulse.

FIG. 10 is a block diagram of a conventional actuator driving circuit using an electromechanical transducer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Actuator 11 Fixed member 12 Piezoelectric element 13 Drive shaft (drive member) 14 Slider (movable member) 15 Position sensor 20 CPU 21 Signal processing circuit 22 Coarse drive circuit 23 Fine drive circuit 24 Variable frequency band blocking filter circuit 25 Switching Switch 26 Voltage amplification circuit

Claims (6)

[Claims] An electromechanical transducer comprising an electromechanical transducer, a drive member fixedly coupled to the electromechanical transducer and displaced with the electromechanical transducer, and a moving member frictionally coupled to the drive member. A drive circuit suitable for the actuator, comprising: a position detector for detecting a position of the moving member; and a drive signal generating circuit for generating a drive signal for generating a displacement in the electromechanical transducer. A center frequency variable band rejection filter circuit that is inserted on the output side of the drive signal generation circuit and includes a unit that changes a center frequency based on a position signal output from the position detector; and Drive control means for controlling the drive signal by feeding back the output position signal to the drive signal generation circuit and setting the moving member at a predetermined position. Akuchie using air transducer - driving circuit suitable for data. 2. The means for changing the center frequency of the band rejection filter circuit sets the center frequency high when the moving member frictionally coupled to the driving member is on the side closer to the electromechanical transducer. 2. A drive circuit suitable for an actuator using an electromechanical transducer according to claim 1, wherein the center frequency is set to be lower when the electromechanical transducer is farther from the electromechanical transducer. 3. A circuit according to claim 2, wherein said means for changing the center frequency of said band rejection filter circuit is a circuit including a semiconductor element for changing the center frequency by controlling a gate voltage with said position signal. A drive circuit suitable for an actuator using the electromechanical transducer according to claim 1. 4. The apparatus according to claim 1, wherein said means for changing the center frequency of said band rejection filter circuit is a circuit for changing the center frequency by multiplying said drive signal and said position signal by a multiplication circuit. A drive circuit suitable for an actuator using the electromechanical transducer described in the above. 5. An electromechanical transducer comprising an electromechanical transducer, a driving member fixedly coupled to the electromechanical transducer and displaced with the electromechanical transducer, and a moving member frictionally coupled to the drive member. A driving circuit suitable for the actuator, wherein the driving circuit comprises: a position detector for detecting a position of the moving member; and a speed detector for continuously driving the electromechanical transducer to expand and contract. A first motor that generates different reciprocating vibrations and moves a moving member frictionally coupled to the driving member at a high speed.
A first drive signal generation circuit for generating a drive signal for the first mode, and a second mode drive signal for generating a displacement in the electromechanical transducer to move the drive member and the moving member frictionally coupled to the drive member. A second drive signal generating circuit for generating, a mode switching means for switching between the first mode and the second mode, and a position detector inserted at an output side of the second drive signal generating circuit, A center frequency variable band rejection filter circuit comprising means for changing the center frequency based on the position signal output from the position detector;
Drive control means for controlling the drive signals of the mode and the second mode and setting the moving member at a predetermined position, which is suitable for an actuator using an electromechanical transducer. Drive circuit. 6. A driving circuit suitable for an actuator using an electromechanical transducer according to claim 5, wherein said first driving signal generating circuit is a sawtooth wave driving pulse generating circuit.