JP3358244B2 - Drive device for piezoelectric actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device for driving a piezoelectric actuator. The present invention relates to a driving device for a piezoelectric actuator which transmits a signal via a charge signal transmitting photoelectric integrated circuit and a discharge signal transmitting photoelectric integrated circuit.

[0002]

2. Description of the Related Art Piezoelectric actuators are used for precision focusing of a precision microscope, precision positioning of a workpiece, and precision positioning of a cutting tool of a machine tool and a mold of a press machine.
It is attracting attention as an actuator capable of high response and high precision positioning. The piezoelectric actuator is displaced by applying a voltage. If the displacement is controlled by the applied voltage, a hysteresis as shown in FIG. 4 occurs, which is an obstacle to accurate positioning. ing. As a countermeasure, as shown in FIG. 5, the control methods (JP-A 1-99270 discloses the injection amount of charge of the piezoelectric actuator, JP 2-202
384) has been proposed by the present applicant.
In this method, a constant charge is injected at a constant speed in order to displace the target to a target position. As shown in FIG. 6, the charge amount of the piezoelectric actuator 71 and the target value of the piezoelectric actuator 71 are changed. A comparison is made by a detection capacitor 70, and based on the comparison result, a charging MOS-FET 73 and a discharging MOS-FET as switching elements
74 is turned on and off.

However, as shown in FIG. 7, since charge is injected (charged) and discharged (discharged) at a constant speed, overshoot and chattering occur near the target value due to a response delay of the piezoelectric actuator. This makes it difficult to perform high-speed and high-accuracy positioning. Conversely, if the charge injection speed is reduced to prevent chattering, the positioning speed will be reduced. Therefore, the present applicant has proposed a piezoelectric actuator control device (Japanese Patent Laid-Open No. 5-1112) capable of controlling a piezoelectric actuator with high speed and high accuracy.
No. 66).

According to the piezoelectric actuator control device, as shown in FIG. 2, a value corresponding to the expansion and contraction is detected by the position sensor 7, and the differential amplifier circuit 8 expands and contracts the piezoelectric actuator 1 by the position sensor 7. values and deviation between the target value of the piezoelectric actuator 1 is obtained, response <br/> Ji was to be a charging and discharging the positive half-wave rectifier circuit 9 and the negative half-wave rectifier circuit 10 to the deviation in accordance with the Controlled. Then, in order to control the amount of injected electric charge with high accuracy, this is a method in which the insulated charge field effect transistor 19 and discharge field effect transistor 30 at the final stage are linearly controlled using the linear integrated circuits 15 and 16. In this method, a signal of a signal system is converted into a charge current adjustment linear integrated circuit 15 and a discharge current adjustment linear integrated circuit 1 at the last stage.
6, photocouplers 27 and 38 are used. Since the expansion / contraction energy is determined by the applied voltage value because the piezoelectric actuator 1 is a capacitive load, the charging current adjusting linear integrated circuit 15 operates using the voltage of the piezoelectric actuator 1 as a base voltage, This is because it must be insulated from the system. Therefore, the secondary side of the photocouplers 27 and 38 is a phototransistor, and is a single-ended element for controlling the secondary side voltage.

[0005]

However, according to the control device for a piezoelectric actuator, it is the charging field effect transistor 19 that finally drives the charging current adjusting circuit 15 and causes the current to flow through the piezoelectric actuator 1. To drive the charging field effect transistor 19, a gate-source voltage (V _GS ) is required.
Driving cannot be performed without a power source (power source) for generating _VGS of the charging field effect transistor 19. Further, when actually used, a power supply is used to stably and linearly control the current flowing through the piezoelectric actuator 1 via the charging field effect transistor 19 (including correction of the temperature characteristics of each element). Since the V _GS of the charging field effect transistor 19 must be linearly controlled and applied, the linear integrated circuit 21 is used. Since the charging current adjusting circuit 15 needs to be insulated from the signal system for the above-described reason, the power supply and the linear integrated circuit 2
1 is an element insulated from the signal system. Further, energy for driving the power supply can be given only to the signal system potential. Therefore, this power supply is energized by the signal system potential (primary side), and the secondary side generates a secondary side voltage based on the potential of the piezoelectric actuator 1. As described above, in the piezoelectric actuator control device,
Since a floating power supply and a linear integrated circuit with insulated input and output are required, the number of components is increased, and a large and expensive driving device is required. SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has a small number of parts and is suitable for a small and inexpensive piezoelectric actuator by directly transmitting an analog signal to an insulated charging field transistor and a discharging field effect transistor. It is an object to provide a driving device.

[0006]

According to the present invention, a control circuit for outputting a position command signal corresponding to a target position of a piezoelectric actuator is provided as specific means for solving the above-mentioned problems.
A position sensor that detects a real position accompanying expansion and contraction of the piezoelectric actuator and outputs a position signal, and outputs a positive or negative signal by comparing and amplifying a position command signal from the control circuit and a position signal from the position sensor. Differential amplifying means, positive signal half-wave rectifying means for transmitting a positive signal of the differential amplifying means to charging current controlling amplifying means, and negative signal half-wave for transmitting a negative signal to discharging current controlling amplifying means. Rectifying means, a charging / discharging current detecting means for detecting a current actually flowing to the piezoelectric actuator and outputting a signal, a detection signal from the charging / discharging current detecting means, and a positive signal of the positive signal half-wave rectifying means. A charge current control amplifier for comparing and amplifying; a discharge current control amplifier for comparing and amplifying a detection signal from the charge / discharge current detector with a negative signal of the negative signal half-wave rectifier; A high-voltage power supply, a charging switching means for charging the voltage of the high-voltage power supply to the piezoelectric actuator, a discharging switching means for discharging the voltage of the piezoelectric actuator, and a charging signal from the charging current control amplifying means. A charge signal transmitting photoelectric integrated circuit for transmitting to the insulated switching means for charging and operating the switching means for charging, and transmitting a discharge signal from the amplifying means for discharging current control to the insulated switching means for discharging; Further, there is provided a driving device for a piezoelectric actuator, comprising: a discharge signal transmitting photoelectric integrated circuit for operating the discharge switching means.

[0007]

According to the driving device for a piezoelectric actuator having the above structure, the position command signal from the control circuit and the position signal from the position sensor are compared and amplified by the differential amplifying means, and the charging current control amplifying means is changed to the positive signal half-wave. The positive signal from the rectifier and the signal from the charge / discharge current detector are compared and amplified, and the discharge current control amplifier is a negative signal from the negative signal half-wave rectifier and the charge / discharge current detector. The signal from the charging current control amplifier is directly transmitted to the charging field effect transistor by the charging signal transmitting photoelectric integrated circuit. Further, the signal from the discharge current control amplifying means is directly transmitted to the discharge field effect transistor by the discharge signal transmitting photoelectric integrated circuit.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the driving device for a piezoelectric actuator according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a circuit diagram showing the overall configuration of the present embodiment. As shown in FIG. 8, the structure of the piezoelectric actuator in FIG.
And many piezoelectric elements 19 are alternately stacked one by one. Each piezoelectric element 19 is electrically connected in parallel, and expands and contracts in the laminating direction according to an increase or decrease in applied voltage.

In this embodiment, a piezoelectric actuator 1, a high-voltage power supply 2 as a charging power supply, a control circuit 3, a position sensor 4, a differential amplifier circuit 5 as a differential amplifier, a positive signal half wave A positive signal half-wave rectifier 6 as a rectifier, a negative signal half-wave rectifier 7 as a negative signal half-wave rectifier, a charge current control amplifier 8 as a charge current control amplifier, and a discharge current control. Circuit 9 for discharging current control, which is an amplifying means
, A charge signal transmission photovoltaic IC (product name) 12 which is a charge signal transmission photoelectric integrated circuit, and a discharge signal transmission photovoltaic IC (product name) 13 which is a discharge signal transmission photoelectric integrated circuit
And a field effect transistor (FET) 14 as a switching means for charging, a field effect transistor (FET) 15 for discharging as a switching means for discharging, and a charging / discharging current detecting circuit 16 as a charging / discharging current detecting means. Is done. The resistors 10 and 11 are resistors for limiting the primary current of the photovoltaic ICs 12 and 13.

A current detecting resistor 20 in a charge / discharge current detecting circuit 16 is connected in series to the piezoelectric actuator 1,
The reverse terminal of the current detection resistor 20 is grounded. This current detection resistor is for detecting a charging current and a discharging current of the piezoelectric actuator 1 accompanying the charging / discharging operation of the piezoelectric actuator 1. And actually, the piezoelectric actuator 1
Is generated as an electromotive voltage of the current detection resistor 20, and a positive voltage is generated when the piezoelectric actuator 1 is being charged, and a negative voltage is generated when the piezoelectric actuator 1 is being discharged.

The photovoltaic ICs 12 and 13 are devices that generate a voltage on the secondary side according to the magnitude of the current flowing on the primary side. The charging (MOS) FET 14 and the discharging (MOS) FET 15 at the final stage are generated by the secondary voltage.
Drive. In addition, since the photovoltaic IC generally has a small output on the secondary side, the current can be controlled by the gate voltage, such as a MOSFET, and is effective for controlling devices that can operate even when the gate current is low. is there. Even a bipolar transistor can be used if it has a very high current amplification factor and can operate even with a weak base current.

Since the primary and secondary sides of the photovoltaic ICs 12 and 13 are completely insulated, the signal system and the power system can be completely completely electrically controlled. Therefore,
In this embodiment, since the piezoelectric actuator 1 is a capacitive load, even if the source voltage of the charging FET 14 rises and falls due to the applied voltage, the secondary voltage of the charging signal transmission photovoltaic IC 12 will remain at the source of the charging FET 14 The charging MOSFET 14 is generated as a voltage with respect to the voltage.
The gate voltage of the piezoelectric actuator 1
It is easy to control the charging current of the device by a signal system.

Charge FET 1 as a power MOSFET
To drive the FET 4 and the discharging FET 15, a gate voltage of about 5 V or more is required. Photovolt IC12,1
In the structure of No. 3, a plurality of photodiodes are connected in an array on the secondary side, and an electromotive force is generated on the secondary side by light emitted from the primary side infrared LED (light emitting diode). The necessary gate voltage of the charging FET 14 and the discharging FET 15 uses this electromotive voltage. The discharge signal transmitting photovoltaic IC 13 and the discharging FET 15 also have the same functions as the charging signal transmitting photovoltaic IC 12 and the charging FET 14.

The control circuit 3 outputs an analog command signal (target value signal) V _S at a level corresponding to the target position of the piezoelectric actuator 1. The position sensor 4 detects an actual position associated with the expansion and contraction operation of the piezoelectric actuator 1, and outputs the detected position as a feedback signal VF _{/ B.} As in the case of the prior art shown in FIG. 6, if it is desired to control the charge amount, the charge / discharge current detection circuit 16 determines that the charge current is a positive voltage.
In addition, since the discharge current is output as a negative voltage, the charge amount can be controlled by integrating the signal with the integration circuit 21 surrounded by a broken line in FIG. 1 and using the integrated signal as the feedback signal V _{F / B} of the position sensor 4. . As shown in FIG. 1, the differential amplifier circuit 5 includes an operational amplifier and a resistor.
Enter the analog command signal V _S from the control circuit 3, an inverting input terminal, the feedback signal V from the position sensor 4
Enter _{F / B.}

The differential amplifier circuit 5 compares and amplifies the analog command signal V _S from the control circuit 3 with the feedback signal V _{F / B} from the position sensor 4 so that the analog command signal V _S becomes the feedback signal. larger than V F _{/ B,} and outputs a positive differential value, an analog command signal V _S is output and a smaller feedback signal V _{F / B,} the negative differential values. As shown in FIG. 1, the positive signal half-wave rectifier circuit 6 receives a signal from the differential amplifier circuit 5 in the form of a resistor and a diode.
Then, a positive signal is output by rectification of the diode.
Like the positive signal half-wave rectifier circuit 6, the negative signal half-wave rectifier circuit 7 receives the signal from the differential amplifier circuit 5 and outputs a negative signal by rectifying the diode.

As shown in FIG. 1, the charging current control amplifier circuit 8 comprises an operational amplifier, a resistor and a diode. The non-inverting input terminal of the operational amplifier of the charge current control amplifier circuit 8 inputs a positive signal (positive voltage) from the positive signal half-wave rectifier circuit 6, and the inverting input terminal of the operational amplifier is connected to the charge / discharge current detection circuit. 16 and the charge current alone is input as a positive signal by diode rectification. Then, the positive output voltage of the positive signal half-wave rectifier circuit 6 and the positive output voltage (charge current value) from the charge / discharge current detection circuit 16 are compared and amplified and output.

As shown in FIG. 1, the discharge current control amplifier circuit 9 comprises an operational amplifier, a resistor and a diode. The non-inverting input terminal of the operational amplifier of the discharge current control amplifier circuit 9 inputs a negative signal (negative voltage) from the negative signal half-wave rectifier circuit 7, and the inverting input terminal of the operational amplifier connects to the charge / discharge current detection circuit. 16 and the discharge current alone is input as a negative signal by diode rectification. Then, the negative output voltage of the negative signal half-wave rectifier circuit 7 is compared with the negative output voltage (discharge current value) from the charge / discharge current detection circuit 16 to be amplified and output. A resistor 10 for limiting the current on the primary side of the charging signal transmission photovoltaic IC 12
Is given by the positive voltage from the charging current control amplifier circuit 8
This is a voltage-current conversion resistor that determines the primary current value of the charging signal transmission photovoltaic IC 12. The current limiting resistor 11 on the primary side of the charge signal transmission photovoltaic IC 13 is a voltage-current conversion resistor for determining the primary current value of the discharge signal transmission photovoltaic IC 13 by the negative voltage from the discharge current control amplifier circuit 9. It is.

When the analog command signal V _S is larger than the feedback signal V _{F / B} , the output signal (positive signal differential value) from the differential amplifier circuit 5 is rectified by the positive signal half-wave rectifier circuit 6. , The subsequent circuits 8, 10, 12,
Activate 14. At this time, in the negative signal half-wave rectifier circuit 7, the positive output signal from the differential amplifier circuit 5 is rectified and canceled, so that the circuits 9, 11, 13, 1 at the subsequent stage on the discharge side are used.
5 remains stopped. On the other hand, the analog command signal V _S
Is smaller than the feedback signal V _{F / B} , the output signal (negative signal differential value) of the differential amplifier circuit 5 is rectified by the negative signal half-wave rectifier circuit 7, and the subsequent circuits 9, 11, 1
Activate 3,15. At this time, the positive signal half-wave rectifier circuit 6
In this case, since the rectification of the negative output signal from the differential amplifier circuit 5 is canceled, the post-charging-side circuits 8, 10, 12, 14
Remains stopped. On the other hand, the current actually flowing through the piezoelectric actuator 1 is generated as an electromotive voltage of the current detection resistor 20 in the charge / discharge current detection circuit 16, and when the piezoelectric actuator 1 is being charged, it is output as a positive voltage, and is discharged. Is generated as a negative voltage. The signal from the current detection resistor 20 is impedance-converted by the operational amplifier and output.

Here, when the analog command signal V _S is larger than the feedback signal V _{F / B} , the charge current control amplifier circuit 8 outputs the output voltage of the positive signal half-wave rectifier circuit 6 and the positive and negative of the charge / discharge current detection circuit 16. Are compared and amplified, and as the signal of the positive signal half-wave rectifier circuit 6 is larger than the positive signal of the charge / discharge current detection circuit 16, the output voltage increases with the positive voltage. On the other hand, when the feedback signal V _{F / B} is larger than the analog command signal V _S , the discharge current control amplifier circuit 9 outputs the negative output voltage from the negative signal half-wave rectifier circuit 7 and the negative output voltage of the charge / discharge current detection circuit 16. The output is compared and amplified. As the signal of the negative signal half-wave rectifier circuit 7 is smaller than the negative signal of the charge / discharge current detection circuit 16, the output voltage becomes smaller (only negative voltage).

Then, a signal from the charging current control amplifier circuit 8 flows through the primary side limiting resistor 10 of the charging signal transmitting photovoltaic IC 12 to the light emitting diode on the primary side of the charging signal transmitting photovoltaic IC 12, and the secondary Voltage is generated on the side. Here, since the secondary side of the charging signal transmission photovoltaic IC 12 and the charging FET 14 are connected based on the potential of the piezoelectric actuator 1, the base voltage of the charging FET 14 is controlled with respect to the potential of the piezoelectric actuator 1. The Rukoto. Therefore, the larger the positive signal of the charge current control amplifier circuit 8 is, the larger the current flows through the light emitting diode of the charge signal transmission photovoltaic IC 12,
A large voltage is also generated on the secondary side. Therefore, the charging F
The gate voltage of the ET 14 increases, and a large current flows through the charging FET 14. Conversely, the smaller the positive signal of the charge current control amplifier circuit 8 is, the smaller the charge signal transmission photovoltaic I
A small current flows through the light emitting diode C12, and a small voltage is generated on the secondary side. The gate voltage of the charging FET 14 is lowered, and only a small current flows through the charging FET 14. This current is supplied from the high voltage power supply 2 to the charging FET 14
To drive the piezoelectric actuator 1 through the actuator.

The charging current flowing to the piezoelectric actuator 1 via the charging FET 14 is detected by a charging / discharging current detection circuit 16 and fed back to the charging current control amplification circuit 8 to form a closed loop. The temperature characteristics of the charge transfer photovoltaic IC 12, or the secondary side voltage is accidentally change, also the gate-source voltage V _GS of the charging FET 14 - the temperature characteristics of the drain current I _D, the positive signal half-wave rectifier When the charging current of the piezoelectric actuator 1 has a temperature characteristic due to a signal from the circuit 6, the closed loop is used for correcting the charging current. For example, when the signal from the positive signal half-wave rectifier circuit 6 is large and the charging current is not sufficient, the charge / discharge current detection circuit 1
Since the voltage from 6 is low, a positive signal is further output by the charging current control amplifier circuit 8 to correct the temperature characteristics and allow the charging current to flow stably over a wide temperature range.

Similarly, when the output voltage of the differential amplifier circuit 5 is negative, it passes through the negative signal half-wave rectifier circuit 7 and the discharge current control amplifier circuit 9 outputs a negative signal (discharge current) from the charge / discharge current detection circuit 16. ) And a negative signal corresponding to the difference is output. Since the anode side of the primary side (light emitting diode) of the discharge signal transmission photovoltaic IC 13 is grounded, the negative side signal from the discharge current control amplifier circuit 9 causes the primary side of the discharge signal transmission photovoltaic IC 13 to output 1
A current flows through the discharge current control amplifier circuit 9 via the secondary current limiting resistor 11 (a current flows on the primary side of the discharge signal transmission photovoltaic IC 13). Then, the discharge FET 15 is controlled by the secondary voltage of the discharge signal transmission photovoltaic IC 13. Therefore, as the negative signal of the discharge current control amplifier circuit 9 becomes smaller, a larger current flows through the light emitting diode of the discharge signal transmitting photovoltaic IC 13 and a larger voltage is generated on the secondary side, so that the gate voltage of the discharge FET 15 is reduced. When it is raised, a large current flows through the discharging FET 15.

Conversely, as the negative signal of the discharge current control amplifier circuit 9 is larger (closer to 0 V), a smaller current flows through the light emitting diode of the discharge signal transmitting photovoltaic IC 13;
A small voltage is also generated on the secondary side, and the gate voltage of the discharging FET 15 is reduced, so that a small current flows through the discharging FET 15. This current is discharged from the piezoelectric actuator 1 via the discharging FET 15, and the piezoelectric actuator 1 performs a contracting operation. The discharge current flowing from the piezoelectric actuator 1 via the discharge FET 15 is detected by the charge / discharge current detection circuit 16 and the discharge current control amplification circuit 9
, And a closed loop is formed as in the case of charging. The closed loop at the time of discharging is the same as the function at the time of charging described above.

As a result, as shown in FIG. 3, when the analog command signal V _S is larger than the feedback signal V _{F / B} ,
The charging current is increased or decreased according to the magnitude of the deviation, and overshoot or chattering caused by the operation delay of the piezoelectric actuator 1 is prevented, thereby enabling a fast extension operation. Also, when the analog command signal V _S is the feedback signal V _{F / B} smaller than, by increasing or decreasing the discharging current of the piezoelectric actuator 1 in the magnitude of the deviation, indicating the same effect as the charge side.
In this way, based on the magnitude of the analog command signal V _S and the feedback signal V _{F / B,} by changing the charge and discharge current, a stable positioning.

Next, the overall operation of the above-described embodiment will be described. Piezoelectric actuator 1 by position sensor 4
A feedback signal V _{F / B} is transmitted by detecting a position corresponding to the actual expansion and contraction of the piezoelectric actuator 1, and a target value of the feedback signal V _{F / B} and the position of the piezoelectric actuator 1 from the control circuit 3 by the differential amplifier circuit 5. deviation between analog command value V _S is is obtained. Then, of the signals from the differential amplifier circuit 5, the charge command signal is rectified by the positive signal half-wave rectifier circuit 6, and the discharge command signal is rectified by the negative signal half-wave rectifier circuit 7. The charging / discharging current detection circuit 16 detects the current actually flowing through the piezoelectric actuator 1, and at the time of charging, the detection signal and the signal of the positive signal half-wave rectification circuit 6 are sent to the charging current control amplification circuit 8. To perform amplification and correction. Further, at the time of discharging, the signal of the charge / discharge current detection circuit 16 and the signal of the negative signal half-wave rectification circuit 7 are compared and amplified by the discharge current control amplifier circuit 9 for correction. Based on the corrected signal, the primary current flowing through the charging signal transmission photovoltaic IC 12 is corrected and controlled via the current limiting resistor 10. In addition, the primary current flowing through the discharge transfer photovoltaic IC 13 is corrected and limited via the current limiting resistor 11 by the corrected signal from the discharge current control amplifier circuit 9. As a result, overshoot and chattering caused by the operation delay of the piezoelectric actuator 1 are prevented, and the piezoelectric actuator 1 is controlled with high speed and high accuracy.

As described above, according to the present embodiment, the power source (power source) for driving the charging FET 14 for supplying the charging current to the piezoelectric actuator 1 is generated on the secondary side of the charging signal transmission photovoltaic IC 12. This is very effective when controlling a capacitive load such as the piezoelectric actuator 1. In addition, the secondary voltage of the charging signal transmission photovoltaic IC 12 has a high gate impedance such as an FET because only a small amount of current can flow, and it is also very effective to use a device that does not require much current to drive the FET. It is. As a result, a floating power supply and a linear control IC are not required, and a small and inexpensive piezoelectric actuator driving device can be configured.

The differential amplifier circuit 5, the positive signal half-wave rectifier circuit 6, the negative signal half-wave rectifier circuit 7, the charge current control amplifier circuit 8, the discharge current control amplifier circuit 9, and the charge / discharge current detection in this embodiment. The circuit configuration of the circuit 16 is not limited to that shown in FIG. 1, but is merely an example of a generally known circuit configuration. Therefore, any circuit configuration that satisfies these functions may be used. A specific product name of a photovoltaic IC applicable to the present embodiment is an infrared LE manufactured by Toshiba Corporation.
D + photodiode array TLP591A or the like.

The present invention is not limited to the above embodiment. For example, when a piezoelectric actuator is applied to a hydraulic system (when the hydraulic pressure is increased or decreased by expansion and contraction of the piezoelectric actuator), the position sensor 4 may be replaced. Alternatively, a hydraulic pressure sensor may be used. When the piezoelectric actuator is controlled according to the amount of charge injected, a charge detection sensor may be used instead of the position sensor 4. For example, like the integration circuit shown by the broken line in FIG.
Outputs a charge current value (positive voltage) and a discharge current value (negative voltage), and integrates these values by an integration circuit to obtain a position integration 4
This is made possible by using it as a charge detection sensor instead of

[0029]

The driving device for a piezoelectric actuator according to the present invention has the above-mentioned structure, and has excellent effects of a small number of parts, small size and low cost.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an electrical configuration of an embodiment of the present invention.

FIG. 2 is a circuit diagram showing an electrical configuration of a conventional example.

FIG. 3 is a time chart showing a relationship between a current and a signal during charging and discharging.

FIG. 4 is a graph illustrating a relationship between an applied voltage and a displacement amount of a piezoelectric actuator.

FIG. 5 is a graph showing the relationship between the amount of charge injected and the amount of displacement of a piezoelectric actuator.

FIG. 6 is a circuit diagram showing an electrical configuration of a conventional example.

FIG. 7 is a time chart in a conventional control device for a piezoelectric actuator.

FIG. 8 is an exploded perspective view showing the structure of the piezoelectric actuator.

[Explanation of symbols]

1. Piezoelectric actuator 2. High voltage power supply 3.
Control circuit, 4 .. Position sensor, 5 ... Differential amplifier circuit, 6 ... Positive signal half-wave rectifier circuit, 7 ... Negative signal half-wave rectifier circuit, 8 ... Charge current control amplifier circuit, 9 ... Discharge Amplifying circuit for current control, 12 ... photoelectric integrated circuit (photovoltaic IC) for transmitting charging signal, 13. Photoelectric integrated circuit (photovoltaic IC) for transmitting discharge signal, 14. Field effect transistor (FET) for charging, 15 ... Field effect transistor (FET) for discharging, 16 ... Charge / discharge current detection circuit.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-111266 (JP, A) JP-A-1-99270 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02N 2/00 G05D 3/00 H01L 41/09

Claims (1)

(57) [Claims] A control circuit for outputting a position command signal corresponding to a target position of the piezoelectric actuator; a position sensor for detecting a real position accompanying expansion and contraction of the piezoelectric actuator and outputting a position signal; A differential amplifier for comparing and amplifying a position command signal and a position signal from the position sensor to output a positive or negative signal; and a positive amplifier for transmitting a positive signal of the differential amplifier to a charging current control amplifier. Signal half-wave rectification means and negative signal half-wave rectification means for transmitting a negative signal to the discharge current control amplification means; charge / discharge current detection means for detecting a current actually flowing to the piezoelectric actuator and outputting a signal; A charge current control amplifier for comparing and amplifying a detection signal from the charge / discharge current detector and a positive signal of the positive signal half-wave rectifier, and a detection signal from the charge / discharge current detector. A discharge current control amplifying means for comparing and amplifying a negative signal of the negative signal half-wave rectifying means; a high voltage power supply for generating a positive voltage; a charging switching means for charging a voltage of the high voltage power supply to the piezoelectric actuator; A discharging switching means for discharging the voltage of the piezoelectric actuator; and a charging signal for transmitting a charging signal from the charging current control amplifying means to the insulated charging switching means and operating the charging switching means. A transmission photoelectric integrated circuit, and a discharge signal transmission photoelectric integrated circuit for transmitting a discharge signal from the discharge current control amplifying means to the insulated discharge switching means and operating the discharge switching means , The charging signal transmission photoelectric integrated circuit is configured to receive the charging signal.
A light emitting diode that emits light to the primary side
Generating electromotive voltage by light emitted from photodiode
Multiple photodiodes connected in an array
Side, and the secondary side electromotive voltage
Therefore, the charging switching means is driven.
And the discharge signal transmitting photoelectric integrated circuit receives the discharge signal.
A light emitting diode that emits light to the primary side
Generating electromotive voltage by light emitted from photodiode
Multiple photodiodes connected in an array
Side, and the secondary side electromotive voltage
Therefore, the discharge switching means is driven.
A driving device for a piezoelectric actuator.