JPH0365067A - Driver of piezoelectric actuator - Google Patents

Abstract

PURPOSE:To enable accurately controlling the output displacement of a piezoelectric actuator by providing a drive circuit for charging the piezoelectric actuator with a constant current or discharging the actuator and a controller for outputting a control signal to the drive circuit to control the operating time of the drive circuit. CONSTITUTION:An apparatus is equipped with a drive circuit 2 for charging a piezoelectric actuator 1 with a constant current or discharging the actuator. The output of a central control unit (CPU) 3 for controlling the output of the drive circuit 2 via control signal for controlling the charge time or discharge time is connected with the input of the drive circuit 2. The piezoelectric actuator 1 is charged with a constant current for a predetermined period of time or discharged so that the potential of the piezoelectric actuator is increased or decreased by the repetition of the charge or discharge to a target potential corresponding to a desired output displacement. In this manner, it is possible to accurately control the output displacement of the piezoelectric actuator 1 including an intermediate displacement.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive device for a piezoelectric actuator, and more particularly to a drive device that accurately controls the output displacement of the actuator.

In general, a piezoelectric actuator is composed of a dielectric piezoelectric element and two electrodes sandwiching the piezoelectric element, so the piezoelectric actuator can be regarded as a type of capacitor. The axial deformation of the piezoelectric actuator has been controlled by charging or discharging the piezoelectric actuator by switching the electric power stored in the piezoelectric actuator.

However, with simple switching, it is not possible to control the charging and discharging time, and the current value fluctuates during charging and discharging, making it impossible to accurately manage the amount of charge and discharge. ,
There has been a problem in that it is difficult to accurately control the output displacement of the piezoelectric actuator, especially the intermediate displacement.

Therefore, the present invention accurately controls the amount of charge, the amount of discharge, and the output displacement of the piezoelectric actuator, including the intermediate displacement, by controlling the charging and discharging time and keeping the current constant during charging and discharging. An object of the present invention is to provide a piezoelectric actuator driving device that can perform the following steps.

According to the present invention, in order to solve the above problem, there is provided a drive device for a piezoelectric actuator, which includes a drive circuit for charging or discharging a piezoelectric actuator with a constant current, and a drive circuit. and a control device for outputting a control signal to control the operating time of the drive circuit, and charging or discharging the piezoelectric actuator with a constant current for a predetermined time to a target potential corresponding to a desired output displacement. A device is provided in which the potential of the piezoelectric actuator is increased or decreased by repeating the steps.

According to a preferred embodiment of the present invention, the drive circuit includes:
A DC power source, a pair of transistors connected in series to the series power source via a constant current circuit, and another constant current circuit connected between the pair of transistors and ground, The piezoelectric actuator is connected between the transistor connection line and ground.

(Function) As described above, the present invention includes a drive circuit for charging or discharging the piezoelectric actuator with two constant currents, and a control for outputting a control signal to the drive circuit to control the operating time of the drive circuit. Since the piezoelectric actuator is equipped with a device, it is possible to charge and discharge the piezoelectric actuator with a constant current for a predetermined time, that is, it is possible to accurately manage the amount of charging and discharging. Accurate control of displacement is possible.

X intention Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a diagram schematically showing the configuration of an embodiment of a drive device according to the present invention. The illustrated drive device includes a drive circuit 2 for charging or discharging the piezoelectric actuator l with a constant current. The input of the drive circuit 2 is connected to the output of a central control unit (CPU) 3 for controlling the output of the drive circuit 2 via a control signal that controls the charging time or discharging time.

FIG. 2 schematically shows the configuration of the drive circuit 2. As shown in FIG. The illustrated circuit includes a constant current circuit 21 consisting of, for example, one resistor, one end of which is connected to a DC power source (not shown).

The other end of constant current circuit 21 is connected to the emitter of transistor 23.

The base of transistor 23 is connected to the output terminal of central control unit 3, and the collector of transistor 23 is connected to the collector of another transistor 24. The base of the transistor 24 is connected to the output terminal of the central control device 3;
The emitter of the transistor 24 is another constant current circuit 2
2 to ground. The above DC power supply,
The pair of transistors 23 and 24 and the pair of constant current circuits 21 and 22 constitute the drive circuit 2.

The connection line between the collector of the transistor 23 and the collector of the transistor 24 is branched and connected to the piezoelectric actuator 1.
The other electrode of the piezoelectric actuator l is connected to ground.

The operation of the drive device according to this embodiment configured as described above will be described below.

When the central controller 3 applies a charge trigger signal to the base of the transistor 23 for a predetermined period of time, the transistor 23 becomes conductive for a predetermined period of time, and the DC power supply is connected to the piezoelectric actuator 1 via the constant current circuit 21 and the transistor 23 for a predetermined period of time. In this way, a constant DC current is applied to the piezoelectric actuator 1 for a predetermined period of time, and the piezoelectric actuator 1 is charged by a predetermined amount of charge. Thereby, the piezoelectric actuator 1 is displaced by a predetermined amount.

On the other hand, when the central controller 3 applies a discharge trigger signal to the base of the transistor 24 for a predetermined time, the transistor 24 becomes conductive for a predetermined time, and the piezoelectric actuator 1 is connected to the ground for a predetermined time via the constant current circuit 22 and the transistor 24. . In this way, the piezoelectric actuator l discharges a predetermined amount of charge. Thereby, the displacement of the piezoelectric actuator l is reduced by a predetermined amount.

By setting the constant current value and the signal transmission time to appropriate values, as shown in Fig. 3, accurate output displacement control of the piezoelectric actuator including intermediate displacement can be achieved by repeating charging and discharging. can.

That is, in FIG. 3, by repeating charging three times, the output of the piezoelectric actuator increases stepwise from the initial value, that is, zero, through two intermediate displacements and reaches the maximum value. Thereafter, by repeating the discharge three times, the voltage gradually decreases from the maximum value through two intermediate displacements and returns to the initial value, that is, zero.

As described above, in the piezoelectric actuator drive device according to the present invention, the charging and discharging time of the piezoelectric actuator is controlled, and the current during charging and discharging is maintained constant, so that the amount of charging and discharging can be controlled. quantity and thus the output displacement of the piezoelectric actuator,
In particular, intermediate displacement can be precisely controlled.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically showing the configuration of an example of a drive device according to the present invention, and FIG. 2 is a diagram schematically showing the configuration of an example of a drive circuit used in the device of the present invention. be. FIG. 3 is a diagram showing an example of the operation of the drive device according to the present invention. DESCRIPTION OF SYMBOLS 1... Piezoelectric actuator, 2... Drive circuit, 3... Central control unit, 2322... Constant current circuit, 23.24... Transistor. Figure 1 Figure 2

Claims (2)

[Claims] (1) A drive device for a piezoelectric actuator, which includes a drive circuit for charging or discharging the piezoelectric actuator with a constant current, and a control device for outputting a control signal to the drive circuit to control the operating time of the drive circuit. A device comprising: charging or discharging a piezoelectric actuator with a constant current for a predetermined period of time, and increasing or decreasing the potential of the piezoelectric actuator by repeating charging or discharging until a target potential corresponding to a desired output displacement is reached. (2) The drive circuit includes a DC power supply, a pair of transistors connected in series to the DC power supply via a constant current circuit, and another constant current transistor connected between the pair of transistors and ground. The device according to claim 1, further comprising a circuit, and wherein the piezoelectric actuator is connected between a connection line of the pair of transistors and ground.