JPH1118458A - Driving circuit of drive device using electrical mechanical sensing element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving circuit which can compensate changes in driving speed, based on the temperature characteristics of an electrical mechanical sensing element, and attain sufficient driving speed at all times. SOLUTION: This driving circuit is provided with a current 1 charging circuit 33 for charging a piezoelectric element 15 rapidly with a heavy current, a current 1 discharging circuit 34 for discharging rapidly with heavy current, a current 2 charging circuit 35 for charging with constant current, and a current 2 discharging circuit 36 for discharging with constant current, and as a result of charging and discharging rapidly with constant current, a moving member frictionally combined with a driving member is moved in a prescribed direction by generating extending displacement smoothly and rapidly-contracting displacement in a piezoelectric element, and generating reciprocating vibration whose speed is different at the driving members fixed to the piezoelectric element. By inserting the temperature compensating thermistors TH1, TH2 in the constant current charging circuit 35 and the constant current discharging circuit 36, it is possible to compensate for the changes in a constant current charging current and a constant current discharging current, based on a change in the electrostatic capacity of the piezoelectric element 15 generated by the change in the environmental temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device using an electromechanical transducer, and more particularly to an electromechanical transducer capable of obtaining a constant driving speed even when the temperature of the electromechanical transducer changes. The present invention relates to a driving circuit of a driving device.

[0002]

2. Description of the Related Art A driving member is connected to an electromechanical transducer,
An actuator (hereinafter referred to as an impact type actuator) for applying a sawtooth drive pulse to the electromechanical transducer to reciprocate the drive member in the axial direction and moving the moving member frictionally coupled to the drive member in the axial direction. Is called).

[0003] This type of impact type actuator generally operates as follows. First, at the gentle rising portion of the sawtooth wave driving pulse applied to the electromechanical transducer, the electromechanical transducer is gently extended in the thickness direction and displaced, and the driving member coupled to the electromechanical transducer is also gently displaced in the positive direction. I do. At this time, the moving member is connected to the driving member by a frictional coupling force, and moves in the forward direction together with the driving member.

[0004] Next, at the rapid falling portion of the sawtooth wave driving pulse applied to the electromechanical transducer, the electromechanical transducer rapidly shrinks and displaces in the thickness direction, and the driving member coupled to the electromechanical transducer is also required. Displaces rapidly in the negative direction. At this time, the moving member frictionally coupled to the driving member stays at that position by overcoming the frictional coupling force due to the inertial force and does not move.
By continuously applying the sawtooth wave driving pulse to the electromechanical transducer, the moving member can be continuously moved in a predetermined direction.

In order to move the moving member in the opposite direction, the waveform of the sawtooth wave driving pulse applied to the electromechanical transducer is changed to form a sawtooth wave driving pulse having a rapid rising portion and a gentle falling portion. Can be achieved by applying

[0006] The movement of the driving member and the moving member frictionally connected to the driving member is actually more complicated, and slippage occurs on the friction coupling surface both in the positive displacement and in the negative displacement of the driving member. However, it is considered that the driving member and the moving member move in the gentle displacement direction of the driving member as a whole while reciprocating while sliding.

[0007]

Generally, an electromechanical transducer such as a piezoelectric element has a characteristic that the capacitance increases when the temperature of the electromechanical transducer is high and decreases when the temperature is low. It has.

Due to this characteristic, when the electromechanical transducer is charged with a constant current to drive it, the higher the temperature of the electromechanical transducer, the greater the capacitance and the gentler the sawtooth waveform of the drive pulse. The inclination angle θ of the rising portion becomes small. On the other hand, the lower the temperature of the electromechanical transducer,
The capacitance decreases, and the inclination angle θ of the gentle rising portion of the sawtooth waveform of the drive pulse increases.

That is, when the temperature greatly deviates from the reference temperature (for example, 25 ° C.), an optimum drive waveform (for example, a drive waveform set so as to have an optimum inclination angle θ based on the time of 25 ° C.) is obtained. And the driving efficiency is reduced.

As described above, in a driving device using a conventional electromechanical transducer, the driving speed fluctuates based on the temperature characteristics of the electromechanical transducer. Therefore, depending on the temperature of the environment in which the driving device is used, There is a disadvantage that a sufficient driving speed cannot be obtained. An object of the present invention is to solve the above problems.

[0011]

Means for Solving the Problems The present invention solves the above-mentioned problems, and the invention of claim 1 is to supply a driving power to an electromechanical transducer to generate a telescopic displacement in the electromechanical transducer. A driving circuit for driving the driving member, the driving circuit using an electromechanical conversion element for moving a driven member frictionally coupled to the driving member in a predetermined direction, a charging circuit for charging the electromechanical conversion element with a constant current; A discharge circuit for discharging electric charges of the electromechanical transducer, and a control circuit for switching connection between the electromechanical transducer, the charging circuit, and the discharge circuit at a predetermined timing to generate expansion and contraction displacement in the electromechanical transducer. And a current compensation circuit attached to the charging circuit that adjusts a constant current amount supplied from the charging circuit to the electromechanical transducer in accordance with a change in environmental temperature. Always regardless of the change of the environmental temperature and controls the charging and discharging current to the electromechanical transducer so that a constant displacement rate.

The current compensating circuit is a current compensating circuit for compensating a change in charging current based on a change in capacitance of the electromechanical transducer due to a change in environmental temperature. Specifically, the current compensating circuit is A resistor for changing a resistance value in accordance with a change in environmental temperature to compensate for a change in charging current.

According to a fourth aspect of the present invention, a driving member is driven by supplying driving power to the electromechanical transducer and causing the electromechanical transducer to expand and contract. In a drive circuit of a drive device using an electromechanical transducer that moves in a predetermined direction, a current compensation circuit that compensates for a change in charging current based on a change in capacitance of the electromechanical transducer that changes in accordance with a change in environmental temperature A first charging circuit that charges the electromechanical transducer with a constant current in which a change in environmental temperature is compensated, a first discharge circuit that discharges electric charges of the electromechanical transducer, and the electromechanical transducer And a current compensation circuit for compensating for a change in discharge current based on a change in capacitance of the electromechanical transducer that fluctuates in accordance with a change in environmental temperature. A second discharging circuit for discharging the electric charge of the electromechanical transducer with the compensated constant current, and the first charging circuit and the first discharging circuit for the electromechanical transducer according to the driving direction of the driving device. A control circuit for switching connection at a predetermined timing, or a control circuit for switching and connecting the second charging circuit and the second discharging circuit to the electromechanical conversion element at a predetermined timing, regardless of a change in environmental temperature. The present invention is characterized in that the charging / discharging current to the electromechanical transducer is controlled so as to obtain a constant displacement speed.

[0014]

Embodiments of the present invention will be described below. Embodiments of the present invention described below are:
In this example, a driving device using the electromechanical transducer of the present invention is applied to a photographic lens driving mechanism of a camera, and a piezoelectric element is used as the electromechanical transducer.

FIG. 1 is a sectional view showing a configuration of a photographing lens driving mechanism of a camera suitable for applying the present invention. FIG.
In the figure, reference numeral 11 denotes a lens barrel, on the left end of which a fixed frame 12 for the first lens L1 is fixedly attached, and the right end 11a thereof forms a frame for holding the third lens L3. Inside the lens barrel 11, a lens holding frame 13 of the second lens L2 is disposed so as to be movable in the optical axis direction. Reference numeral 14 denotes a drive shaft for driving the lens holding frame 13 in the optical axis direction. The drive shaft 14 is movable in the optical axis direction by the first flange 11b of the lens barrel 11 and the flange 12b of the lens holding frame 12. , One end of which is bonded and fixed to one surface of the piezoelectric element 15.

The piezoelectric element 15 is displaced in the thickness direction to displace the drive shaft 14 in the axial direction. One end surface of the piezoelectric element 15 is bonded and fixed to the drive shaft 14, and the other end surface is the second end of the lens barrel 11.
Is adhesively fixed to the flange portion 11c.

A lens holding frame 1 for holding the second lens L2
Reference numeral 3 denotes a slider block 13b which is a moving member extending upward. A drive shaft 14 extends through the slider block 13b in the lateral direction. Slider block 1
An opening 13c is provided in the upper part through which the drive shaft 14 of FIG.
Are formed, and the upper half of the drive shaft 14 is exposed. A pad 16 which is in contact with the upper half of the drive shaft 14 is fitted into the opening 13c.
6a, the projection 16a of the pad 16 is pushed down by the leaf spring 17, and the pad 16
Downward urging force F is applied. FIG. 2 is a cross-sectional view showing a configuration of a frictional coupling portion between the drive shaft 14, the slider block 13b, and the pad 16.

Reference numeral 18 denotes a guide shaft for preventing the lens holding frame 13 from swinging and guiding the lens holding frame 13 to move along the optical axis.
Reference numeral 7 denotes a lens position detecting sensor for detecting the position of the lens L2, which can detect the position of the lens holding frame 13 to know the lens position.

Next, the control operation will be described. Lens L2
When the movement in the direction of arrow a is required, a driving pulse having a sawtooth waveform composed of a gently rising portion as shown in FIG.

In the gentle rising portion of the driving pulse,
The piezoelectric element 15 gradually expands in the thickness direction, and the drive shaft 14 is axially displaced in the direction of arrow a. For this reason,
The slider block 13b and the pad 16, which are urged by the leaf spring 17 and are frictionally coupled to the drive shaft 14, also move in the direction of the arrow a, so that the lens holding frame 13 can be moved in the direction of the arrow a.

At the rapid falling portion of the drive pulse, the piezoelectric element 15 rapidly contracts in the thickness direction, and the drive shaft 14 is also displaced in the axial direction in the direction opposite to the arrow a. At this time, the slider block 13b, the pad 16 and the lens holding frame 13, which are urged against the drive shaft 14 by the leaf spring 17 and pressed against it, substantially overcome the frictional coupling force with the drive shaft 14 due to its inertia force. Lens holding frame 13 does not move.

The term "substantially" as used herein means that the slider block 13b and the frictional coupling surface between the pad 16 and the drive shaft 14 slide in the direction of the arrow a and in the direction opposite thereto while sliding. However, this also includes the movement in the direction of arrow a as a whole due to the difference in driving time.

By continuously applying the driving pulse having the above-mentioned waveform to the piezoelectric element 15, the lens holding frame 13
Can be continuously moved in the direction indicated by.

The movement of the lens holding frame 13 in the direction opposite to the arrow a is achieved by applying a drive pulse having a waveform consisting of a rapid rising portion followed by a gentle falling portion to the piezoelectric element 15. Can be.

FIG. 4 is a block diagram of a driving circuit of the piezoelectric element. The drive circuit 30 connects the piezoelectric element 15 to two different current values.
It is driven by charging and discharging with two kinds of currents 1 and 2 (current 1> current 2). By driving with two kinds of currents having different current values, the piezoelectric element 15 can expand and contract at different speeds. it can.

The drive circuit 30 includes a control circuit 31, a lens L
Input device 3 for inputting the target position when moving 2
2, current 1 charging circuit 33, current 1 discharging circuit 34, current 2
It comprises a charging circuit 35, a current 2 discharging circuit 36, and a lens position detecting sensor 37 for detecting the position of the lens L2, that is, the current position of the lens holding frame 13.

The input device 32 corresponds to, for example, a rotation angle detector of a zoom operation ring when the lens L1 is moved by a zoom operation in a zoom lens. The lens position detection sensor 37 is connected to the lens holding frame 1.
For example, a magnetized rod arranged in parallel with the drive shaft 14 and a magnetoresistive element provided on the lens holding frame 13 close to the magnetized rod and detecting the magnetized rod. A known position detector composed of elements can be used. The magnetizing rod can also be used as a guide shaft 18 for guiding the lens holding frame 13.

The control circuit 31 calculates the moving direction and the moving distance of the lens based on the signals inputted from the input device 32 and the lens position detecting sensor 37, determines the charging circuit and the discharging circuit to be used, and determines the current 1 charge. PWM signals (pulse width modulation signals) PWM1, PWM2, PWM3, PWM for setting the circuit 33, the current 1 discharging circuit 34, the current 2 charging circuit 35, and the current 2 discharging circuit 36 to be activated or deactivated.
M4 is output.

FIG. 5 is a diagram showing a circuit configuration of the current 1 charging circuit 33, the current 1 discharging circuit 34, the current 2 charging circuit 35, and the current 2 discharging circuit 36.

The current 1 charging circuit 33 is a circuit for rapidly charging the piezoelectric element 15 with a large current.
Operates, the piezoelectric element 15 is rapidly extended and displaced.
The current 1 discharge circuit 34 rapidly discharges the electric charge of the piezoelectric element 15 with a large current. When the current 1 discharge circuit 34 operates, the piezoelectric element 15 is rapidly contracted and displaced.

The current 2 charging circuit 35 includes a current 1 charging circuit 33
Since the electric charge is gradually charged in the piezoelectric element 15 with a constant current charging circuit having a smaller current, the piezoelectric element 15 is gradually expanded and displaced when the current 2 charging circuit 35 operates. The current 2 discharge circuit 36 is a constant current discharge circuit having a smaller current than the current 1 discharge circuit 34 and slowly discharges the electric charge of the piezoelectric element 15.
When the element 6 operates, the piezoelectric element 15 contracts gently to cause displacement.

The reason why the current 2 charging circuit 35 is a constant current charging circuit and the current 2 discharging circuit 36 is a constant current discharging circuit is that the piezoelectric element 15 is gradually extended or contracted, as is apparent from the driving principle. This is because the moving member can be moved faster by displacing it at the same speed as possible.

A current compensating thermistor TH1 for compensating the temperature characteristic of the piezoelectric element is inserted in the current 2 charging circuit 35, so that the capacitance of the piezoelectric element 15 caused by the fluctuation of the ambient temperature can be changed. It is configured to compensate for a change in charging current when the piezoelectric element 15 is charged with a constant current via the transistor TR1. The thermistor TH1 for temperature compensation is connected in parallel to the resistor R1 for determining the constant current value, but may be connected in series to the resistor R1.

A temperature compensating thermistor TH2 for compensating for the temperature characteristic of the piezoelectric element is also inserted in the current 2 discharging circuit 36, and the transistor TR3 is also operated by the fluctuation of the capacitance of the piezoelectric element 15 caused by the fluctuation of the environmental temperature. Through the piezoelectric element 15
Is configured to compensate for fluctuations in the discharge current when the charge is discharged with a constant current.

FIG. 6 is a timing chart for explaining the operation timing of the charging / discharging circuit in the feeding operation for moving the lens L2 in the direction of arrow a. FIG. 7 is a timing chart for moving the lens L2 in the direction opposite to the arrow a. 4 is a timing chart for explaining the operation timing of the charge / discharge circuit in operation. Hereinafter, the driving operation of the driving circuit 30 will be described with reference to the timing charts of FIGS. 1, 5, 6, and 7.

First, a description will be given of the case of the extending operation for moving the lens L2 in the direction of the arrow a (see FIG. 1).

In this case, the control circuit 31 calculates the moving direction and the moving distance of the lens based on the signals input from the input device 32 and the lens position detecting sensor 37 as described above, and uses the charging circuit and the discharging circuit. The circuit is determined, and the PWM1 as shown in FIG.
A signal is output, and a PWM2 signal as shown in FIG. Further, for the current 1 charging circuit 33 and the current 2 discharging circuit 36, the PWM3 signal is turned off and the PWM is turned off as shown in FIGS.
The output of four signals is output and set to inoperative.

In the current 2 charging circuit 35, when the PWM1 signal goes to "H" level, the transistor TR5 is turned on, TR2 and TR1 start operating, and the resistor R1 and the resistor R1 are turned on.
A charging current flows to the piezoelectric element 15 via the miscellaneous elements TH1 and TR1, and the piezoelectric element 15 is charged. The current flowing through TR1 is determined by the voltage Vbe between the base and the emitter of TR2 and the combined resistance R of the resistor R1 and the thermistor TH1.
The charging current value i for charging the piezoelectric element 15 is given by the following equation (1).
It becomes the value represented by.

I = Vbe / R (1) where, Vbe = 0.6 V, R = (R 1 · TH 1) / (R
1 + TH1) When the PWM1 signal becomes "L" level, the current 2 charging circuit 3
5 is stopped, and at the same time, the PWM2 signal becomes “H”.
Level, and the field effect transistor FET2 of the current 1 discharge circuit 34 is turned on. FET2 has MOS-F
Since the ET is used, the internal resistance when ON is small and substantially short-circuited.
Discharges rapidly through ET2.

The capacitor C of the current 2 charging circuit 35
1 has a function of accelerating the change time of the switching at which the TR5 is turned on / off, whereby the PWM1 signal and the PWM2
Since it is not necessary to substantially provide an OFF section when switching the signal on / off, the control circuit 31 can easily set the timing of the PWM signal. Current 1 charging circuit 33
Is exactly the same as above, with TR6 on /
This function hastens the change time of the switching to be turned off.

With the above operation, the piezoelectric element 15
(E), a drive pulse having a gentle rising portion and a rapid falling portion as shown in (e) is applied, and the piezoelectric element 15 has a gentle extension displacement in the direction of arrow a and a rapid contraction in the direction opposite to arrow a. A displacing operation can be performed to cause the lens L2 to move in the direction of the arrow a (see FIG. 1) via the drive shaft 14 and the slider block 13b.

Next, a description will be given of the case of a retraction operation for moving the lens L1 in the direction opposite to the arrow a (see FIG. 1).

In this case, the control circuit 31 outputs a PWM3 signal as shown in FIG. 7 (c) to the current 1 charging circuit 33, and outputs a PWM3 signal as shown in FIG. 7 (d) to the current 2 discharging circuit 36. It outputs a PWM4 signal. 7A and 7B for the current 2 charging circuit 35 and the current 1 discharging circuit 34.
As shown in (1), the OFF of the PWM1 signal and the OFF of the PWM2 signal are output and set to inoperative.

In the current 1 charging circuit 33, when the PWM3 signal becomes "H" level, the transistor TR6 is turned on and the FET1 is turned on. Since the internal resistance of the FET 1 is small, the piezoelectric element 15 is connected to the power supply via the FET 1 and is charged rapidly.

When the PWM3 signal goes to "L" level, the transistor TR6 is turned off, the FET1 is also turned off, and the current 1
The charging by the charging circuit 33 is stopped. At the same time PWM4
The signal becomes "H" level, the transistor TR3 of the current 2 discharge circuit 36 is turned on, and the electric charge charged in the piezoelectric element 15 is discharged slowly through the resistor R3 and the thermistor TH2.

With the above operation, the piezoelectric element 15
(E), a drive pulse having a rapid rising portion and a gentle falling portion is applied, and the piezoelectric element 15 has a gentle contraction displacement in the direction opposite to the arrow a and a rapid expansion in the direction of the arrow a. A displacement operation occurs, and a retraction operation of moving the lens L2 in the direction opposite to the arrow a (see FIG. 1) through the drive shaft 14 and the slider block 13b can be performed.

FIG. 8 is a diagram showing the temperature characteristics of the capacitance of the piezoelectric element. As is clear from this figure, the capacitance of the piezoelectric element increases in proportion to the rise in temperature.

FIG. 10 is a diagram showing the relationship between the charging time and the temperature of the piezoelectric element, and FIG. 11 is a diagram showing the relationship between the inclination angle of the driving waveform for charging the piezoelectric element and the temperature, all of which are shown in FIG. 9 shows data on the relationship between the time T1 during which the piezoelectric element is charged up to 30 V and the temperature, and the relationship between the inclination angle .theta. Of the drive waveform and the temperature.

In FIG. 10 showing the relationship between the charging time and the temperature of the piezoelectric element, the line (a) shows the case where the temperature compensation by the thermistor is not performed, and the time T1 for charging the piezoelectric element to 30 V is the temperature. The higher the value, the larger the capacitance, indicating that the charging time becomes longer. The line (b) shows a case where the temperature compensation is performed by the thermistor, and the charging time is not affected by the temperature, and the charging is performed in a substantially constant time.

In FIG. 11, which shows the relationship between the inclination angle of the driving waveform for charging the piezoelectric element and the temperature, the line (a) shows the case where temperature compensation by the thermistor is not performed. Becomes longer, the inclination angle θ becomes smaller,
This indicates that charging to a predetermined voltage becomes difficult, the driving force decreases, and the driving speed decreases. In addition, the lower the temperature, the shorter the charging time, the greater the inclination angle θ, the gentler rising waveform of the drive pulse gradually changes to a faster rising waveform, and the difference in the expansion and contraction speed of the piezoelectric element becomes smaller. Indicates that the driving speed decreases.

The line (b) in FIG. 11 shows the case where the temperature compensation is performed by the thermistor. The inclination angle θ of the driving waveform is kept almost constant without being affected by the temperature, and the driving speed due to the temperature change is changed. It shows that there is no decrease.

[0052]

As described above, the driving circuit of the driving device using the electromechanical transducer of the present invention can compensate for the fluctuation of the driving speed based on the temperature characteristics of the electromechanical transducer. Even when the ambient temperature at which the device is used fluctuates, a sufficient drive speed can always be obtained, and the applicable range of the drive device can be expanded.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a photographing lens driving mechanism of a camera.

FIG. 2 is a cross-sectional view showing a configuration of a frictional coupling portion between a driving shaft of the lens driving mechanism shown in FIG. 1, a slider block, and a pad.

FIG. 3 is a diagram illustrating a waveform of a driving pulse.

FIG. 4 is a block diagram of a driving circuit.

FIG. 5 is a diagram showing a circuit configuration of a current 1 charging circuit, a current 1 discharging circuit, a current 2 charging circuit, and a current 2 discharging circuit.

FIG. 6 is a timing chart for explaining the operation timing of the charge / discharge circuit (part 1).

FIG. 7 is a timing chart for explaining the operation timing of the charge / discharge circuit (part 2).

FIG. 8 is a diagram illustrating temperature characteristics of capacitance of a piezoelectric element.

FIG. 9 is a diagram illustrating a charging time of a piezoelectric element and an inclination angle of a driving waveform.

FIG. 10 is a diagram showing a relationship between charging time and temperature of a piezoelectric element.

FIG. 11 is a diagram illustrating a relationship between a tilt angle of a driving waveform for charging a piezoelectric element and temperature.

[Explanation of symbols]

Reference Signs List 11 lens barrel 13 second lens lens holding frame 13b slider block 14 drive shaft 15 piezoelectric element 30 drive circuit 31 control circuit 32 input device 33 current 1 charge circuit 34 current 1 discharge circuit 35 current 2 charge circuit 36 current 2 discharge circuit 37 Lens position detection sensors FET1, FET2 Field effect transistors TR1, TR2, TR3, TR4, TR5, TR6 Transistors TH1, TH2 Thermistor

Claims (4)

[Claims] 1. A driving power is supplied to an electromechanical transducer,
In a drive circuit of a driving device using an electromechanical conversion element that drives a driving member by generating expansion and contraction displacement in the electromechanical conversion element and moves a driven member frictionally coupled to the driving member in a predetermined direction, A charging circuit for charging the mechanical conversion element with a constant current, a discharging circuit for discharging the electric mechanical conversion element, and switching the connection between the electromechanical conversion element, the charging circuit and the discharging circuit at a predetermined timing. A control circuit for causing the electromechanical transducer to expand and contract; and a current compensation circuit attached to the charging circuit for adjusting the amount of a constant current supplied from the charging circuit to the electromechanical transducer according to a change in environmental temperature. And controlling the charging / discharging current to the electromechanical conversion element so as to always obtain a constant displacement speed irrespective of a change in environmental temperature. A drive circuit of a drive device using a gas-mechanical conversion element. 2. The electric current compensation circuit according to claim 1, wherein the current compensation circuit is a current compensation circuit for compensating a change in charging current based on a change in capacitance of the electromechanical transducer due to a change in environmental temperature. A drive circuit of a drive device using a mechanical conversion element. 3. The electromechanical transducer according to claim 2, wherein the current compensating circuit includes a resistor that changes a resistance value according to a change in environmental temperature to compensate for a change in charging current. The drive circuit of the drive used. 4. A driving power is supplied to the electromechanical transducer,
In a drive circuit of a drive device using an electromechanical transducer, which drives a driving member by causing expansion and contraction displacement in the electromechanical transducer, and moves a driven member frictionally coupled to the drive member in a predetermined direction, an environmental temperature A current compensation circuit that compensates for a change in charging current based on a change in the capacitance of the electromechanical transducer that fluctuates in accordance with a change in the ambient temperature. A first charging circuit, a first discharging circuit for discharging the electric-mechanical conversion element, a second charging circuit for charging the electro-mechanical conversion element, and an electric machine that fluctuates according to a change in environmental temperature A second current discharge circuit that includes a current compensation circuit that compensates for a change in a discharge current based on a change in capacitance of the conversion element, and that discharges the charge of the electromechanical conversion element with a constant current in which a change in environmental temperature is compensated. A first charging circuit and a first charging circuit according to a driving direction of a driving device.
Switching connection with a predetermined timing to the electromechanical conversion element, or the second charging circuit and the second charging circuit
And a control circuit for switching and connecting the discharge circuit to the electromechanical transducer at a predetermined timing, so as to always obtain a constant displacement speed regardless of a change in environmental temperature. A driving circuit of a driving device using an electromechanical transducer, wherein