JP2000287466A - Drive of impact piezoelectric actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the circuit structure of the drive of an impact piezoelectric actuator. SOLUTION: The drive of a piezoelectric actuator comprises a drive circuit 12 consisting of a bridge circuit composed of 1st-4th circuits 121-124 consisting of switch circuits using FET's and 5th and 6th circuits 125 and 126 consisting of series circuits of FET's and resistors R and a control circuit 10 which controls the drive of the drive circuit 12. A power supply is connected between the connection points (a) and (c) of the bridge circuit and a piezoelectric element 3 is connected between the connection points (b) and (d) of the bridge circuit. A power supply voltage Vr is applied to the piezoelectric element 3 while the polarity of the voltage Vr is alternately reversed and the element 3 is charged/ discharged with different current to be expanded/contracted with different speeds. The 5th and 6th circuits 125 and 126 function as limiting circuits of the charging current of the piezoelectric element 3. By limiting the current with resistors R only, the drive circuit can be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a drive device for an impact type piezoelectric actuator.

[0002]

2. Description of the Related Art Conventionally, an impact type in which a driven member is attached to a rod-shaped driving member so as to be movable in the axial direction, and a piezoelectric element is fixed to one end of the driving member so that the polarization direction is aligned in the axial direction. Piezoelectric actuators are known. For example, Japanese Unexamined Patent Publication No. 7-298656 discloses a camera to which an impact type piezoelectric actuator is applied as an actuator of a photographing lens of a camera.

FIG. 18 is a diagram showing a schematic configuration of an impact type piezoelectric actuator disclosed in the publication. 19 and 20 are circuit examples applied to the low-speed charging circuit of the drive circuit of the impact-type piezoelectric actuator, and FIG. 21 is a circuit example applied to the low-speed discharge circuit of the drive circuit of the impact-type piezoelectric actuator. It is.

As shown in FIG. 18, the impact type piezoelectric actuator 100 includes a rod-shaped driving member 101, a driven member 102, a laminated piezoelectric element 103, and a driving circuit 104. The driven member 102 is the driving member 101
Is fixed with a predetermined frictional force, and when a force greater than this frictional force acts, the drive member 101 can move in the axial direction. An object to be driven such as a photographing lens is fixed to the driven member 102. The driving member 10
A laminated piezoelectric element 103 is fixed to one end of the piezoelectric element 1 such that the polarization direction coincides with the axial direction. Electrodes 103a and 103b are formed on both end surfaces of the piezoelectric element 103.
03b is grounded, and the driving circuit 10
4 are connected.

A driving circuit 104 moves the driven member 102 to the tip (open end) side of the driving member 101 (hereinafter, this moving direction is referred to as a positive direction) and a driving circuit 105 for driving the driven member 102. The control circuit 107 includes a reverse drive circuit 106 that moves the base 101 toward the base end (hereinafter, this movement direction is referred to as a reverse direction) and a control circuit 107 that controls the driving of the two drive circuits 105 and 106.

Further, the forward driving circuit 105 is composed of a low-speed charging circuit 105a and a high-speed discharging circuit 105b, and the reverse driving circuit 106 is composed of a high-speed charging circuit 106a and a low-speed discharging circuit 106b. Charging circuit 105a,
Reference numeral 106a denotes a circuit for applying a power supply voltage in the polarization direction to the piezoelectric element 103 (charging the piezoelectric element 103 in the polarization direction) and extending the piezoelectric element 103 in the polarization direction (the axial direction of the driving member 101). The low-speed charging circuit 105a is shown in FIG.
As shown in FIG. 20, a constant current circuit is provided, and the charging speed is suppressed by limiting the charging current.

FIG. 19 shows a constant current charging circuit in which a zener diode ZD is connected in parallel to a fixed bias circuit of a pnp transistor Tr1. The resistors r1 and r2 are bias resistors of the transistor Tr1, and the Zener diode ZD is connected in parallel to the base bias resistor r2. Transistor T by Zener diode ZD
By maintaining the base voltage of r1 at a constant value, the voltage drop of the resistor r1 is stabilized, whereby the collector current is suppressed to a predetermined value.

FIG. 20 shows a configuration in which the parallel circuit of the resistor r2 and the Zener diode ZD in FIG. 19 is replaced with an npn transistor Tr2. The base and the collector of the transistor Tr2 are connected to the emitter and the base of the transistor Tr1, respectively, and the emitter of the transistor Tr2 is connected to the power supply VP. By maintaining the base voltage of the transistor Tr1 at a constant value by the transistor Tr2, the voltage drop of the resistor r1 is stabilized, so that the collector current is suppressed to a predetermined value.

The discharge circuits 105b and 106b apply the potential in the direction opposite to the polarization direction to the piezoelectric element 103 (the electrode 103a is grounded in the figure), and discharge the charged electric charges to expand the expanded piezoelectric element 103. This is a circuit for reducing the size.

FIG. 21 shows a constant current discharging circuit in which a Zener diode ZD is connected between the base of the npn transistor Tr3 and the ground. The resistor r4 is a resistor for limiting the discharge current. By maintaining the base potential of the transistor Tr3 at a predetermined value by the Zener diode ZD, the voltage drop of the resistor r4 is stabilized at a predetermined value, whereby the emitter current (discharge current) flowing through the resistor r4 is suppressed to a predetermined value. It has become so.

The control circuit 107 controls the driving of the forward drive circuit 105 and the reverse drive circuit 106. In the forward drive, the control circuit 107 alternately drives the low-speed charge circuit 105a and the high-speed discharge circuit 106a, In the directional driving, the high-speed charging circuit 105b and the low-speed discharging circuit 106b are alternately driven.

In the forward drive, the low-speed charging circuit 105
a and the high-speed discharge circuit 106a are alternately driven, and the piezoelectric element 103 alternately repeats low-speed expansion and high-speed reduction,
As a result, the driving member 101 repeats the forward low-speed movement and the reverse high-speed movement. On the other hand, in the reverse drive,
When the high-speed charging circuit 105b and the low-speed discharging circuit 106b are driven alternately, the piezoelectric element 103 alternates between high-speed expansion and low-speed reduction, whereby the driving member 101 performs high-speed movement in the forward direction and low-speed movement in the reverse direction. repeat.

The frictional force between the driven member 102 and the driving member 101 is low when the driving member 101 moves at high speed,
When moving at low speed, the driving member 102 moves with the driving member 101 only at low speed.
Therefore, in the forward drive, the driven member 102 moves in the forward direction relatively to the drive member 101, and in the reverse drive, the driven member 102 moves in the reverse direction relative to the drive member 101. Go to

[0014]

By the way, when an impact type actuator is applied as a drive source of an optical system of a portable device such as a camera lens or a binocular lens,
In consideration of weight reduction and miniaturization of portable equipment, it is desirable that the driving circuit be as simple and small as possible. However, the driving circuit 104 of the conventional impact type piezoelectric actuator is configured such that the charging current or the discharging current is limited by the constant current circuit, so that the number of circuit elements is large and it is difficult to reduce the size of the driving circuit 104. ing.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an impact piezoelectric actuator driving apparatus capable of simplifying a circuit configuration and reducing its size.

[0016]

According to the present invention, there is provided a first method for applying a voltage in a polarization direction to a piezoelectric body in order to extend the piezoelectric body.
, A second drive circuit for applying a voltage to the piezoelectric body in a direction opposite to the polarization direction to reduce the piezoelectric body, and the first drive circuit and the second drive circuit alternately. A drive control circuit for driving the piezoelectric body to expand and contract the piezoelectric body, wherein at least one of the first and second drive circuits is a current limiting circuit including only a resistor. (Claim 1).

The impact type piezoelectric actuator comprises a piezoelectric body, a rod-shaped driving member fixed to one end of the piezoelectric body in a polarization direction, and a driven member which is movable in the axial direction by a predetermined frictional force on the driving member. And a driving device for the piezoelectric body, and a voltage in a polarization direction and a voltage in a direction opposite to the polarization direction are alternately applied to the piezoelectric body to vibrate the piezoelectric body, whereby the driving member reciprocates in the axial direction. As a result, the driven member is moved in one direction relative to the driving member. In this case, the speed at which the piezoelectric body is charged in the polarization direction and the speed at which the piezoelectric body is charged in the direction opposite to the polarization direction are made different from each other, so that the expansion speed and the contraction speed of the piezoelectric body (i.e., the forward movement speed and the backward movement of the driving member). A difference is generated in the forward movement and the backward movement, and the driven member moves in one direction relatively to the driving member.

According to the above configuration, one of the first and second drive circuits is provided to provide a speed difference between the charge speed in the polarization direction of the piezoelectric body and the charge speed in the opposite direction to the polarization direction. Since it was configured with a current limiting circuit consisting only of resistors,
As compared with the case where a constant current circuit or the like is used, the circuit configuration of the current limiting circuit is simplified, and the driving device can be simplified and downsized.

Further, according to the present invention, in the driving device for an impact type piezoelectric actuator, the first driving circuit discharges electric charges accumulated in a direction opposite to the polarization direction of the piezoelectric body and charges the electric charges in the polarization direction. Consisting of one charge / discharge circuit,
The second drive circuit comprises a second charge / discharge circuit that discharges the electric charge accumulated in the polarization direction of the piezoelectric body and charges the electric charge in a direction opposite to the polarization direction (claim 2).

According to the above configuration, for example, when the power supply voltage is V _P
When the piezoelectric body voltage V _P is applied alternately to the polarization direction opposite to the direction of it, it is charged and discharged so as to change the voltage between the terminals from the + V _P alternates between -V _P. That is, the piezoelectric body is equivalently driven at a voltage of 2 V _P , and low-voltage driving becomes possible. In addition, a small driving device capable of driving at a low voltage can be configured.

The present invention also relates to a drive device for the impact type piezoelectric actuator, wherein the first to fourth circuits each including a switch circuit are connected in series, and the fifth device includes a series circuit including a switch circuit and a resistor. The circuit and the sixth circuit are connected in parallel to the first circuit and the fourth circuit, respectively, and between the connection point between the second circuit and the third circuit and the connection point between the first circuit and the fourth circuit. A bridge circuit in which a power source is connected, and a piezoelectric body is connected between a connection point between the first circuit and the second circuit and a connection point between the third circuit and the fourth circuit; One drive circuit includes the power supply, the second circuit and the fourth circuit, or the power supply, the second circuit and the sixth circuit, and the second drive circuit includes the power supply, the third circuit and the third circuit. The fifth circuit or the power supply, the third circuit and the Are those constituted by a circuit (claim 3). The switch circuit may be formed of a field effect transistor (claim 4).

According to the above configuration, the driven member can be moved in both directions relative to the driving member by forming the driving circuit with a bridge circuit. The drive circuit including the bridge circuit constitutes a current limiting circuit of the first drive circuit by the second circuit and the sixth circuit (that is, a series circuit of two switch circuits and one resistor), and includes the third circuit and the sixth circuit. Fifth circuit (ie, a series circuit of two switch circuits and one resistor)
Constitutes the current limiting circuit of the second drive circuit, so that a total of six switch circuits and two resistors (total of 8
And a driving circuit that can be driven in both directions with a small number of elements.

[0023]

FIG. 1 is a perspective view showing a schematic configuration of an embodiment of a piezoelectric actuator according to the present invention.
FIG. 2 is a cross-sectional view of a main part showing a mounting state of a contact member to a driving member in the piezoelectric actuator.

The piezoelectric actuator shown in FIG. 1 is an impact type piezoelectric actuator for driving in the forward direction. The piezoelectric actuator 1 includes a support member 2, a piezoelectric member 3, and a driving member 4.
And a driven member 5.

The support member 2 holds the piezoelectric member 3, the driving member 4, and the driven member 5. The support member 2 has a columnar shape, and has a first housing space 202 and a second housing space 203 formed by hollowing out the inside thereof, excluding both ends in the axial direction and a substantially central partition wall 201. . The piezoelectric member 3 is accommodated in the first accommodation space 202 having a short length in the axial direction with the lamination direction coinciding with the axial direction of the support member 2. The driving member 4 and the driven member 5 are accommodated in the second accommodation space 203 having a long axial length.

The piezoelectric member 3 is composed of a plurality of plate-shaped piezoelectric elements having a required thickness, and a laminated piezoelectric body formed by bonding and sandwiching a thin-film electrode (not shown) between the piezoelectric elements. ing. The plurality of piezoelectric elements are stacked such that the polarization directions of adjacent piezoelectric elements are opposite to each other. This is because a driving voltage is applied to each electrode in parallel so that the positive and negative polarities of the adjacent electrodes are opposite to each other, so that each piezoelectric element expands and contracts in the same direction, and a large expansion and contraction amount of the entire piezoelectric member is increased. It is for obtaining.

The piezoelectric member 3 has one end face in the longitudinal direction (hereinafter, referred to as a first end face).
This end face is called a base end face. ) Is fixed to the end face of the first storage space 202 opposite to the partition wall 201. A round hole is formed at the end of the support member 2 where the partition wall 201 and the second accommodating space 203 are adjacent to each other (the end of the support member 2) at the center of the shaft. Penetrating the second
It is accommodated in the accommodation space 203 so as to be movable in the axial direction.
The cross-sectional shape of the driving member 4 is not limited to a round shape, but may be an arbitrary shape such as an elliptical shape or a rectangular shape.

Then, the first housing space 202 of the driving member 4
Is fixed to the other end surface of the piezoelectric member 3 (hereinafter, this surface is referred to as a front end surface), and the end portion of the driving member 4 protruding from the front end portion of the support member 2 is fixed by a leaf spring 6 to a required spring. It is urged toward the piezoelectric member 3 by pressure. The biasing of the driving member 4 by the leaf spring 6 stabilizes the axial displacement of the driving member 4 based on the expansion and contraction operation of the piezoelectric member 3.

The driven member 5 has a base 501 having ears 502 on both sides and a sandwiching member 503 fitted between the ears 502 (see FIG. 2). A hole 504 having a diameter slightly larger than that of the driving member 4 is formed at the base of both ears 502 of the base 501. The hole 504 is provided at a position where a semicircular groove is formed on the surface of the base 501 facing the sandwiching member 503. Driven member 5
As shown in FIG. 2, the driving member 4 is passed through the hole 504 in a loosely fitted state, and the driving member 4 is sandwiched between the base 501 and the sandwiching member 503 to move in the axial direction to the driving member 4. Mounted as possible. A projection 503a projecting from the upper surface of the both ears 502 is formed on the upper portion of the sandwiching member 503, while the projection 503a is formed on the upper surface of the both ears 502.
The leaf spring 7 is fixed so as to be brought into pressure contact with the holding member a. The sandwiching member 503 is urged by the leaf spring 7 toward the drive member 4 with a required spring pressure.

This spring pressure causes a frictional force at the time of forward movement generated between the driving member 4 and the base 501 and the holding member 503 in the axial reciprocation of the driving member 4 based on the expansion and contraction operation of the piezoelectric member 3. And the frictional force at the time of the backward movement is caused to move the driven member 5 relative to the driving member 4. That is, as described later, the piezoelectric member 3 is extended at a high speed and reduced at a low speed (or at a low speed and reduced at a high speed).
Are alternately repeated, whereby the driving member 4 repeats the high-speed forward movement and the low-speed backward movement (or the low-speed forward movement and the high-speed backward movement). At this time, when the driving member 4 moves forward at a high speed, the driving member 4 and the driven member 5
When only the driving member 4 moves forward and moves backward at a low speed, the frictional force increases and the driven member 5 moves back together with the driving member 4, thereby causing the driven member 4 to move backward. The member 5 moves relatively to the driving member 4 in the backward direction (reverse direction). Conversely, when the driving member 4 moves forward at a low speed, the frictional force between the driving member 4 and the driven member 5 increases, and the driven member 5 moves forward together with the driving member 4 and moves backward at a high speed. When this occurs, the frictional force is reduced and only the driving member 4 moves backward, whereby the driven member 5 moves relatively to the driving member 4 in the forward movement direction (forward direction).

In this embodiment, the sandwiching member 50 is used.
Although a leaf spring is used as an urging means for pressing the member 3 against the driving member 4, the invention is not limited to this as long as the urging force is generated. For example, an elastic member such as a coil spring or rubber is used. You can also.

FIG. 3 is a block diagram showing a basic configuration of a driving circuit of the piezoelectric member 3.

The block diagram shown in FIG. 3 shows a piezoelectric member 3 for moving the driven member 5 in the positive direction with respect to the driving member 4.
, And comprises a low-speed charging circuit 8, a high-speed discharging circuit 9, and a control circuit 10. With reference to the polarization direction of piezoelectric member 3 (the direction indicated by arrow P in FIG. 3), negative electrode 301 is grounded, and positive electrode 302 is connected to low-speed charging circuit 8 and high-speed discharging circuit 9.
Drive control signals Sc1 and Sc2 are input from the control circuit 10 to the low-speed charging circuit 8 and the high-speed discharging circuit 9, respectively, and the control circuit 10 drives the low-speed charging circuit 8 and the high-speed discharging circuit 9 (that is, the low-speed charging circuit 8 and the high-speed discharging circuit 9). The connection between the discharge circuit 9 and the piezoelectric member 3) is controlled.

The low-speed charging circuit 8 includes an electrode 301 of the piezoelectric member 3.
Supply voltage V _P is applied, the voltage member 3 at a lower speed than the discharge rate as to charge to the polarization direction (charging direction to enhance the polarization), which corresponds to the first drive circuit of the driving apparatus according to the present invention Things. The high-speed discharge circuit 9 grounds the electrode 301 of the piezoelectric member 3 (that is, applies a potential in the opposite direction to the voltage between the terminals of the piezoelectric member 3), and is stored in the voltage member 3 at a higher speed than the charging speed. This is equivalent to a second driving circuit of the driving device according to the present invention.

The control circuit 10 controls the driving of the low-speed charging circuit 8 and the high-speed discharging circuit 9 and corresponds to the driving control circuit of the driving device according to the present invention. Control circuit 10
Drives the low speed charging circuit 8 and the high speed discharging circuit 9
The drive is performed alternately at c1 and Sc2.

FIG. 4 is a diagram showing an example of a specific circuit of the driving circuit of the piezoelectric member 3 shown in FIG. FIG. 5 is a diagram showing waveforms of control signals Sc1 and Sc2 of the drive circuit of FIG.

FIG. 3 shows that the low-speed charging circuit 8 is constituted by a series circuit of a resistor R1 and a switch element Q1 composed of a P-channel MOSFET (field-effect transistor), and the high-speed charging circuit 9 is composed of an N-channel MOSFET. This is constituted by the switch element Q2. That is, the low-speed charging circuit 8 has a circuit configuration in which the charging current is limited only by the resistor R1, and the high-speed charging circuit 9 has a circuit configuration in which the electrode 302 of the piezoelectric member 3 is directly grounded to discharge without limiting the current. is there. By configuring the current limit with one resistance element as described above, the drive circuit is simplified and downsized.

The gates of the switch elements Q1 and Q2 are connected to control terminals C1 and C2 of the control circuit 10, and the drains are connected to the electrode 302 of the piezoelectric member 3. The source of the switch element Q1 is connected to the power supply VP via the resistor R1, and the source of the switch element Q2 is grounded. In this embodiment, a MOS is used as a switch element.
Although a type FET is used, other electronic switch elements such as a bipolar transistor, a junction type FET, and a GTO (Gate Turn-off Thyristor) may be used.

As shown in FIG. 5, the piezoelectric actuator 1
During the driving of the control circuit 10, drive control signals Sc1, Sc2 are input from the control terminals C1, C2 of the control circuit 10 to the switch elements Q1, Q2, respectively. The drive control signals Sc1 and Sc2 are rectangular wave signals having the same phase. Since the switch element Q1 is a P-channel MOS type FET and the switch element Q2 is an N-channel MOS type FET, both switch elements Q
1, Q2 are turned on / off in opposite phases.

During the charging period, the charging is performed at a low speed, so that the piezoelectric member 3 expands at a low speed, whereby the driving member 4 also moves at a low speed toward the distal end of the supporting member 2 (hereinafter, this direction is referred to as the "positive direction"). Moving. Further, during the discharging period, the accumulated charges are discharged at a higher speed than the charging speed, so that the piezoelectric member 3 contracts at a higher speed than at the time of extension, whereby the driving member 4 also moves the supporting member 2 at a higher speed than at the time of moving in the forward direction. It moves to the base end side (hereinafter, this direction is referred to as “reverse direction”).

Since the driving member 4 moves at a low speed during the forward movement, the frictional force between the driving member 4 and the driven member 5 increases, and the driven member 5 moves together with the driving member 4 in the forward direction. However, when moving in the reverse direction, the driving member 4 moves at high speed, so that the frictional force between the driving member 4 and the driven member 5 decreases, and only the driving member 4 moves in the reverse direction.

Accordingly, the driven member 5 moves only in the forward direction with respect to the driving member 4 by alternately repeating the low speed forward movement and the high speed backward movement of the driving member 4, whereby the driven member 5 is supported. It moves to the tip side of the member 3.

FIG. 6 is a diagram showing an example of a specific circuit of an impact type piezoelectric actuator for driving in the reverse direction. Also,
FIG. 7 is a diagram showing waveforms of the drive control signals Sc1 and Sc2 of the drive circuit of FIG.

The driving circuit of the impact type piezoelectric actuator for reverse driving is a high-speed charging circuit (first driving circuit),
It is composed of a low-speed discharge circuit (second drive circuit) and a control circuit. The drive circuit shown in FIG. 6 uses a series circuit of a resistor R2 and a switch element Q4 formed of a P-channel MOS FET as a discharge circuit, and a switch element Q3 formed of an N-channel MOS FET as a charge circuit. That is, the gates of the switch elements Q3 and Q4 are connected to the control terminals C1 and C2 of the control circuit 10, and the drains are connected to the electrode 302 of the piezoelectric member 3. The source of the switching element Q4 is grounded via the resistor R2, the source of the switching element Q3 is connected to the power supply V _P.

Since the drive circuit of FIG. 6 has a charging speed and a discharge speed that are opposite to those of the drive circuit of FIG. 4, the driven member 5 moves only in the reverse direction with respect to the drive member 4.
The support member 3 can be moved to the base end side.

As shown in FIG. 7, the piezoelectric actuator 1
During the driving, drive control signals Sc1 and Sc2 are input from the control terminals C1 and C2 of the control circuit 10 to the switch elements Q3 and Q4, respectively. The drive control signals Sc1, S1 shown in FIG.
The waveform of c2 has a relationship in which the waveforms of the drive control signals Sc1 and Sc2 in FIG. Although the drive control signals Sc1 and Sc2 are rectangular wave signals having the same phase, the switch element Q3 is an N-channel MOS type FET and the switch element Q4 is a P-channel MOS type FET. ON / OFF with opposite phases
Turn off.

Since charging is performed at a high speed during the charging period, the piezoelectric member 3 expands at a high speed, whereby the driving member 4 also moves in the positive direction at a high speed. However, during the discharging period, the accumulated charges are discharged at a lower speed than the charging speed. As a result, the piezoelectric member 3 contracts at a lower speed than at the time of extension, whereby the driving member 4 also moves in the reverse direction at a lower speed than at the time of the forward movement. Therefore, during the forward movement, the frictional force between the driving member 4 and the driven member 5 becomes small, the driven member 5 stops, and only the driving member 4 moves in the forward direction. On the other hand, when moving in the reverse direction, the frictional force between the driving member 4 and the driven member 5 increases, and the driven member 5 moves in the reverse direction together with the driving member 4.

Therefore, the driven member 5 moves only in the reverse direction with respect to the driving member 4 by alternately repeating the high-speed forward movement and the low-speed backward movement of the driving member 4, whereby the driven member 5 is supported. It moves to the base end side of the member 3.

The drive circuit shown in FIG. 4 and the drive circuit shown in FIG. 6 are basic structures for moving the driven member 5 only in the forward direction or in the reverse direction, respectively, and as shown in FIG. If connected in parallel to the member 3, the driven member 5 can be moved in both forward and reverse directions.

When the piezoelectric actuator 1 is driven, the control terminals C1 to C4 of the control circuit 10 switch the switch elements Q1 to Q4.
4, the following drive control signals Sc1 to Sc4 are input. That is, when the driven member 5 is moved in the forward direction, the high-level drive control signal Sc3 and the low-level drive control signal SC4 are input to the switch elements Q3 and Q4, respectively, and turned off, and the switch elements Q1 and Q2 are turned off. 5 has the same waveform as the drive control signals Sc1 and Sc2.
c1 and Sc2 are input. On the other hand, when the driven member 5 is moved in the reverse direction, the high-level drive control signal Sc1 and the low-level drive control signal Sc2 are input to the switch elements Q1 and Q2, respectively, and turned off. The drive control signals Sc3 and Sc4 having the same waveform as the drive control signals Sc1 and Sc2 of No. 7 are input. Note that the operation mechanism of the driven member 5 is the same as that described above, and will not be described.

FIG. 9 is a diagram showing a basic configuration in the case where the forward drive circuit and the reverse drive circuit are constituted by bridge circuits.

In the figure, a parallel circuit 12A of a first circuit 121 and a fifth circuit 125, a second circuit 122, a third circuit 123, and a parallel circuit 12B of a fourth circuit 124 and a sixth circuit 126 are connected in series. A bridge circuit 12 is configured. Connection point a between the second circuit 122 and the third circuit 123
The power supply 11 is connected between the power supply 11 and a connection point c between the parallel circuit 12A and the parallel circuit 12B, and the second circuit 122 and the parallel circuit 1
The piezoelectric element 3 is connected between the connection point b of 2A and the connection point d of the third circuit 123 and the parallel circuit 12B. The positive and negative polarities of the power supply 11 connected between the connection points a and c and the polarization direction of the piezoelectric element 3 connected between the connection points b and d can be arbitrarily set. Each of the circuits 121, 122, 123,
Reference numerals 124, 125, and 126 each include a switch circuit, and control terminals C1, C2, C3, C4, and C4 of the control circuit 10, respectively.
5, C6 to drive control signals Sc1, Sc2, Sc3, Sc4, S
c5 and Sc6 are input.

Now, assuming that a circuit connected in series to the piezoelectric element 3 between the connection points a and c is K _{i, j} (i indicates an i-th circuit and j indicates a j-th circuit), a circuit K _3,1 And the circuits K _3,5 constitute a one-way drive circuit α, and the circuits K _2,4 and K
_{2, 6} constitute a driving circuit β in the other direction.

Then, for example, when the piezoelectric element 3 is
And the positive electrode of the power supply 11 is set to the connection point a side,
Assuming that the drive circuit α is a reverse drive circuit and the drive circuit β is a forward drive circuit, the drive circuits α and β are: reverse drive circuit α: circuit K _2,4 + circuit K _3,5 forward drive circuit β: It is composed of the circuit K _2,6 + the circuit K _3,1 .

[0055] In this case, the circuit K _{2, 4} is the circuit for charging at a high speed until the power supply voltage is applied to V _P to the polarization direction of the piezoelectric element 3 is a voltage Vs between the terminals becomes + V _P (hereinafter, the charging circuit of the direction . the positive charging circuit hereinafter), and the circuit K _{3, 5} discharges the electric charge at a low speed by applying a power supply voltage V _P to the polarization direction opposite to the piezoelectric element 3, and the inter-terminal voltage Vs - _VP
(Hereinafter, a charging circuit in this direction is referred to as a reverse charging circuit).

[0056] Further, the circuit K _{2, 6} are inter-terminal voltage Vs is applied a power supply voltage V _P to the polarization direction of the piezoelectric element 3 is the power supply voltage V _P
Forward becomes a charging circuit, the circuit K _{3, 1} discharges the charges at a high speed by applying a power supply voltage V _P to the polarization direction opposite to the piezoelectric element 3, and terminal voltage of charging at a low speed until the V
s is the reverse charging circuit for charging until the -V _P.

That is, the reverse driving circuit α is composed of a high-speed forward charging circuit K _2,4 and a low-speed reverse charging circuit K _3,5 ,
The forward drive circuit β includes a slow forward charge circuit K _2,6 and a fast reverse charge circuit K _3,1 .

The circuits K _2,4 constitute a first drive circuit in the reverse drive of the drive device according to the present invention, and the circuits K _3,5 constitute a second drive circuit in the reverse drive of the drive device. Is composed. Further, the circuits K _2,6 constitute a first drive circuit in the forward drive of the same drive device, and the circuits K _3,1
Constitutes a second drive circuit in the forward drive of the drive device.

Further, the polarity of the power supply 11 is inverted, and the connection point c
Assuming that the positive side is positive, the charge / discharge circuits of the drive circuits α and β are: reverse drive circuit α: circuit K _3,1 + circuit K _2,6 forward drive circuit β: circuit K _3,5 + circuit K _2, Consists of _four .

In this case, the circuit K_3,1Is fast forward charging times
Road and circuit K_2,6Is a low-speed reverse charging circuit.
Circuit K_3,5Is a slow forward charging circuit, and the circuit K_2,4
Is a high-speed reverse charging circuit, so the reverse driving circuit α is
High-speed positive charging circuit K_3,1And low-speed reverse charging circuit K_2,6When
And the forward drive circuit β is a slow forward charge circuit K
_{Three ,Five}And fast reverse charging circuit K_2,4It is composed of

Accordingly, in this case, the circuit K _3,1 constitutes a first drive circuit in the reverse drive of the drive device according to the present invention, and the circuit K _2,6 constitutes the second drive circuit in the reverse drive of the drive device. Of the driving circuit. Further, the circuits K _3,5 constitute a first drive circuit in the forward drive of the same drive device,
The circuits K2 and _K4 constitute a second drive circuit in the forward drive of the drive device.

[0062] When configured in the driver circuit bridge circuit, since the piezoelectric element 3 charging voltage of -V _P ~ + V _P is applied, equivalently driving voltage 2V _P next to the piezoelectric element 3, FIG. 8 The driving voltage is twice as high as the driving circuit shown in
There is an advantage that a piezoelectric actuator having a large displacement amount at a low voltage can be formed.

FIG. 10 is a diagram showing a first embodiment of a specific circuit configuration of a drive circuit using a bridge circuit.

The drive circuit shown in FIG. 9 has a specific circuit configuration for the drive circuits α and β described above. First circuit 1
21 and the fourth circuit 124 are P-channel MOSFETs
The second circuit 122 and the third circuit 123 are composed of N-channel MOSFETs, and the fifth circuit 125 and the sixth circuit 126 are composed of a resistor R and an N-channel MOSFET.
And a series circuit. 1st circuit 121 to 6th
The gate of each FET of the circuit 126 is connected to the control circuit 10
And drive control signals Sc1 to Sc6 from the control circuit 10, respectively. The connection points a and c are respectively connected to a power supply 11 (not shown).
Are connected to a positive electrode and a negative electrode (ground point), and a power supply voltage _VP is supplied to a connection point a.

The MOS type FET is connected to a forward charging circuit K._2,4,
K_2,6And reverse charging circuit K_3,1, K_{Three ,Five}To the piezoelectric element 3
Switch circuit for controlling the connection of
Charging circuit K_3,5And low-speed positive charging circuit K_2,6Is the resistance R
The charging current of the piezoelectric element 3 is limited only by
You. Therefore, the fifth circuit 125 and the sixth circuit 126 are referred to as examples.
For example, as compared with the case where the constant current circuit shown in FIG.
Reduce the number of transistors by one (two in total)
Can be.

FIG. 11 is a diagram showing the drive control signals of the drive circuit shown in FIG. 10 and the waveforms of the charge and discharge voltages of the piezoelectric elements.

In the figure, in the reverse drive,
Because the first circuit 121 and the sixth circuit 126 do not form the reverse drive circuit α due to the circuit configuration of the reverse drive circuit α,
The low-level drive control signals Sc1 and Sc6 are output from the control terminals C1 and C6 of the control circuit 10, and the FETs of the first circuit 121 and the sixth circuit 126 are turned off (cut off). The third circuit 123, the fourth circuit 124, and the fifth circuit 125 form a bridge circuit.

The control terminals C2 and C2 of the control circuit 10
4, the drive control signals Sc2, Sc4 are output in opposite phases, the control terminals C3, C5 of the control circuit 10 output drive control signals Sc3, Sc5 in opposite phases, and the signal Sc3 becomes the signal Sc4. Sc5 is output so as to be in phase with the signal Sc2.
_2,4 (the first circuit 124 + the second circuit 122) and the low-speed reverse charging circuit K _3,5 (the third circuit 123 + the fifth circuit 125) are alternately connected to the piezoelectric element 3 so that the high-speed Forward charging (high-speed extension) and low-speed reverse charging (low-speed reduction)
Are performed alternately.

In the high-speed forward charging, the power supply voltage V _P is directly applied to the piezoelectric element 3, so that the terminal voltage Vs of the piezoelectric element 3
Changes linearly from −V _P to + V _P, but the power supply voltage V _P is applied to the piezoelectric element 3 via the resistor R in the low-speed reverse charging, so that the terminal voltage Vs of the piezoelectric element 3 is with a time constant determined by the third capacitor C and the resistance R + V _P ~ -
It changes exponentially to V _P.

Accordingly, the piezoelectric element 3 alternates between high-speed extension and low-speed reduction alternately, whereby the driving member 101 reciprocates at different speeds, and the driven member 102 is driven in the opposite direction (proximal direction).

In the forward drive, the fifth circuit 125 and the fourth circuit 1
24 does not constitute the forward drive circuit β, low-level drive control signals Sc4 and Sc5 are output from the control terminals C4 and C5 of the control circuit 10, and the FETs of the fifth circuit 125 and the fourth circuit 124 are turned off ( The first circuit 121, the second circuit 122, the sixth circuit 126, and the third circuit 123 equivalently constitute a bridge circuit.

The control terminals C2 and C2 of the control circuit 10
6, the drive control signals Sc2, Sc6 are output in opposite phases, the drive control signals Sc1, Sc3 from the control terminals C1, C3 of the control circuit 10 have opposite phases, and the signal Sc1 is the signal Sc6, and the signal Sc1 is the signal Sc6. Sc3 is output so as to be in phase with the signal Sc2.
_2,6 (the second circuit 122 + the sixth circuit 126) and the high-speed reverse charging circuit K _3,1 (the third circuit 123 + the first circuit 121) are alternately connected to the piezoelectric element 3 so that the low-speed Forward charging (low speed extension) and high speed reverse charging (high speed reduction)
Are performed alternately.

[0073] slow the power supply voltage V _P to the piezoelectric element 3 in the positive direction the charge power supply voltage V _P to the piezoelectric element 3 is applied via the resistor R, the terminal voltage Vs of the piezoelectric element 3 is the piezoelectric element 3
Is a time constant determined by the capacitance C and the resistance R of -V _P to + V _P
Since the power supply voltage _VP is directly applied to the piezoelectric element 3 in high-speed reverse charging, the piezoelectric element 3
The terminal voltage Vs changes linearly until + V _P ~-V _P.

Accordingly, the piezoelectric element 3 alternately repeats the low-speed extension and the high-speed reduction, whereby the driving member 101 reciprocates at different speeds, and the driven member 102 is driven in the forward direction (tip direction). In the above description, the first circuit 121 and the sixth circuit 126 are turned off in the forward drive, and the fourth circuit 124 and the fifth circuit 125 are turned off in the reverse drive. However, the dotted lines of the signals Sc5 and Sc6 in FIG. As shown by the portion, the fifth circuit 125 at the time of reverse driving is the first circuit 121
The sixth circuit 126 may be turned on / off in the same phase as that of the fourth circuit 124 during the forward driving.

FIG. 12 is a diagram showing a second embodiment of a specific circuit configuration of a drive circuit using a bridge circuit.

The drive circuit shown in FIG. 10 has a specific circuit configuration for the drive circuits α and β described above. In FIG. 10, the polarity of the power supply voltage is reversed, that is, the connection points a and c are set.
The second circuit 122 and the third circuit 123 are N-channel MOS type FETs, and the first circuit 121, the fourth circuit 124 to the fourth circuit 124 are connected to the negative electrode (ground point) and the positive electrode of the power supply 11 (not shown). 6 circuits 126 are P channel MOS type FET
It consists of. The other configuration is the same as that of FIG. 10, and the description is omitted.

FIG. 13 is a diagram showing the drive control signal of the drive circuit shown in FIG. 12 and the waveform of the charge / discharge voltage of the piezoelectric element.

In the figure, in the reverse drive,
Since the fifth circuit 125 and the fourth circuit 124 do not form the reverse drive circuit α due to the circuit configuration of the reverse drive circuit α,
The high-level drive control signals Sc4 and Sc5 are output from the control terminals C4 and C5 of the control circuit 10, and the FETs of the fifth circuit 125 and the fourth circuit 124 are turned off (cut off). The second circuit 122, the third circuit 123, and the sixth circuit 126 form a bridge circuit.

Then, the control terminals C1, C of the control circuit 10
3, the drive control signals Sc1, Sc3 are output in opposite phases, the control terminals C2, C6 of the control circuit 10 output drive control signals Sc2, Sc6 in opposite phases, and the signal Sc2 becomes the signal Sc3. Sc6 is output so as to be in phase with the signal Sc1, respectively.
_3,1 (third circuit 123 + first circuit 121) and low-speed reverse charging circuit K _2,6 (second circuit 122 + sixth circuit 126) are alternately connected to piezoelectric element 3 so that high-speed operation of piezoelectric element 3 Forward charging (high-speed extension) and low-speed reverse charging (low-speed reduction)
Are performed alternately.

In the forward drive, the first circuit 121 and the sixth circuit 1
26 does not constitute the forward drive circuit β, high-level drive control signals Sc1 and Sc6 are output from the control terminals C1 and C6 of the control circuit 10, and the FETs of the first circuit 121 and the sixth circuit 126 are turned off ( The second circuit 122, the third circuit 123, the fourth circuit 124, and the fifth circuit 125 equivalently constitute a bridge circuit.

The control terminals C3 and C of the control circuit 10
5, the drive control signals Sc3 and Sc5 are output in opposite phases, the drive control signals Sc2 and Sc4 from the control terminals C2 and C4 of the control circuit 10 have opposite phases, and the signal Sc2 is the signal Sc5. Sc4 is output so as to be in phase with the signal Sc3.
_3,5 (the third circuit 123 + the fifth circuit 125) and the high-speed reverse charging circuit K _2,4 (the second circuit 122 + the fourth circuit 124) are alternately connected to the piezoelectric element 3 so that the low-speed operation of the piezoelectric element 3 Forward charging (low speed extension) and high speed reverse charging (high speed reduction)
Are performed alternately.

The terminal voltage Vs of the piezoelectric element 3 at the time of driving is
Are the same as those in FIG. 11, and the description of the operations of the piezoelectric element 3, the driving member 101, and the driven member 102 will be omitted.

Also in this case, the signals Sc5 and Sc6 shown in FIG.
As shown by the dotted line, the fifth circuit 125 in the reverse drive is turned on / off in the same phase as the first circuit 121, and the sixth circuit 126 in the forward drive is turned on / off in the same phase as the fourth circuit 124. You may do so.

FIG. 14 is a diagram showing a third embodiment of a specific circuit configuration of a drive circuit using a bridge circuit.

In the third embodiment, the driving circuit 1 shown in FIG.
2 and the logic circuit 127
And a driving circuit 12 ′ which is a modified circuit of the driving circuit 12.
Is controlled by the output signal of the logic circuit 127. In the third embodiment, the control circuit 10 and the logic circuit 127 constitute a drive control circuit of the drive device according to the present invention.

In the control of the drive circuit 12 shown in FIG. 10, the fifth circuit 125 becomes a component of the bridge circuit in the backward drive, and the sixth circuit 126 becomes a component of the bridge circuit in the forward drive. It does not become a component of the bridge circuit (see the drive control signals Sc5 and Sc6 in FIG. 11). That is, in the drive circuit 12 shown in FIG. 10, the resistor R for limiting the charging current in the forward drive and the resistor R for limiting the current in the reverse drive are separately provided. However, since both resistors R do not become circuit elements of the bridge circuit at the same time, it is possible to share one resistor R, which can reduce the number of resistors R and simplify the bridge circuit. Can be.

The drive circuit 12 ′ according to the third embodiment shares the resistor R of the fifth circuit 125 and the resistor R of the sixth circuit 126 of the drive circuit 12 shown in FIG.
Specifically, in FIG. 10, one of the resistors R of the fifth circuit 125 and the sixth circuit 126 is removed, and the fifth circuit 1
In this case, the drain of the FET 25 is connected to the drain of the FET of the sixth circuit 126 (see the connection point e).

Therefore, the first circuit 12 of the drive circuit 12 '
1, second circuit 122, third circuit 123, and fourth circuit 12
4 is the same as the corresponding circuit of the drive circuit 12, but the fifth circuit 125 of the drive circuit 12 'is composed of the switch element Q5 and the resistor R, and the sixth circuit 126 is composed of the switch element Q6 and the resistor R. Is done.

Then, the second circuit 12 of the drive circuit 12 '
2, third circuit 123, fifth circuit 125, and sixth circuit 12
6 are connected to output terminals P2, P3, P5, and P6 of a logic circuit 127, and drive control signals Sp2, Sp3, Sp5, and S5 from the logic circuit 127, respectively.
p6 is input. Logic circuit 127
Are connected to control terminals C7 and C8 of the control circuit 10, respectively, and the logic circuit 127 converts the drive control signals Sc7 and Sc8 input from the control circuit 10 into the drive control signals Sp2 according to the logic shown in Table 1 below. , Sp3, Sp5,
The data is converted to Sp6 and output.

[0090]

[Table 1] Further, the first circuit 121 and the fourth circuit 1 of the drive circuit 12 ′
The gate of each of the 24 FETs is connected to the control terminal C of the control circuit 10.
1 and C4, and drive control signals Sc1 and Sc4 are input from the control circuit 10, respectively.

FIG. 15 is a diagram showing the drive control signals of the drive circuit shown in FIG. 14 and the waveforms of the charge and discharge voltages of the piezoelectric elements.

In the figure, in the reverse drive,
Since the first circuit 121 does not constitute the reverse drive circuit α due to the circuit configuration of the reverse forward drive circuit α, the low-level drive control signal Sc1 is output from the control terminal C1 of the control circuit 10, and the first circuit 121 The FET is turned off (disconnected).
In the first embodiment, since the sixth circuit 126 does not constitute the reverse drive circuit α, the FET of the sixth circuit 126 is also turned off. However, in the third embodiment, the FET of the sixth circuit 126 is turned off. Is controlled by the output signal Sp6 of the logic circuit 127, so that the FET of the sixth circuit 126 is controlled to be on / off even in the reverse drive. But the sixth
Since the FET of the fourth circuit 124 (short circuit) connected in parallel to the sixth circuit 126 is also turned on and off in synchronization with the turning on and off of the FET of the circuit 126 (current limiting circuit) (the drive of FIG. 15). Control signals Sc4, Sp6), sixth
The circuit 126 operates as a part of the fourth circuit 124, and does not substantially constitute the reverse drive circuit α.

In the reverse drive, as described in the bridge circuit according to the first embodiment, the F of the second circuit 122, the third circuit 123, the fourth circuit 124, and the fifth circuit 125
By controlling ON / OFF of the ET, high-speed expansion and low-speed reduction of the piezoelectric element 3 are controlled. In the third embodiment, the ON / OFF control of the FETs of the second circuit 122, the third circuit 123, the fourth circuit 124, and the fifth circuit 125 is performed by the drive control signals Sp2, Sp3, Sc4, and Sp5. The waveforms of the drive control signals Sp2, Sp3, Sc4, and Sp5 correspond to the drive circuit 1
2 have the same waveforms as the corresponding drive control signals Sc2, Sc3, Sc4, Sc5, the voltage Vs between the terminals of the piezoelectric element 3 changes in the same manner as when driven by the drive circuit 12 according to the first embodiment. (See the comparison between the signal waveform of FIG. 15 and the signal waveform of FIG. 11).

In the forward drive, since the fourth circuit 124 does not constitute the forward drive circuit β due to the circuit configuration of the forward drive circuit β, the control terminal C4 of the control circuit 10
Outputs a low-level drive control signal Sc4, and the FET of the fourth circuit 124 is turned off (disconnected). The first
In the third embodiment, since the fifth circuit 125 does not constitute the forward drive circuit β, the FET of the fifth circuit 125 is also turned off. However, in the third embodiment, the F of the fifth circuit 125 is turned off.
ET is controlled by the output signal Sp5 of the logic circuit 127.
The ET is on / off controlled. However, the fifth circuit 125
The first circuit 121 connected in parallel to the fifth circuit 125 in synchronization with the ON / OFF of the FET of the (current limiting circuit)
Since the (short circuit) FET is also turned on and off (see the drive control signals Sc1 and Sp5 in FIG. 15), the fifth circuit 12
5 operates as a part of the first circuit 121, and does not substantially constitute the forward drive circuit β.

In the forward drive, as described in the bridge circuit according to the first embodiment, the F of the first circuit 121, the second circuit 122, the third circuit 123, and the sixth circuit 126 are used.
By controlling ON / OFF of the ET, low-speed expansion and high-speed reduction of the piezoelectric element 2 are controlled. In the third embodiment, the ON / OFF control of the FETs of the first circuit 122, the second circuit 122, the third circuit 123, and the sixth circuit 126 is performed by the drive control signals Sc1, Sp2, Sp3, and Sp6. The waveforms of the drive control signals Sc1, Sp2, Sp3, and Sp6 correspond to the drive circuit 1
2 have the same waveforms as the corresponding drive control signals Sc1, Sc2, Sc3, Sc6, the voltage Vs between the terminals of the piezoelectric element 3 changes in the same manner as when driven by the drive circuit 12 according to the first embodiment. (See the comparison between the signal waveform of FIG. 15 and the signal waveform of FIG. 11).

Therefore, the piezoelectric element 3 is the first element of the bridge circuit.
The expansion and contraction operation is performed by the same mechanism as when driven by the drive circuit 12 according to the embodiment. Note that the operations of the piezoelectric element 3, the driving member 101, and the driven member 102 are the same as those in the case where the bridge circuit is driven by the driving circuit 12 according to the first embodiment of the bridge circuit, and thus the description is omitted.

FIG. 16 is a diagram showing a fourth embodiment of a specific circuit configuration of a drive circuit using a bridge circuit.

The fourth embodiment is a modification of the circuit configuration of the drive circuit 12 'according to the third embodiment.

In the drive circuit 12 'according to the third embodiment, the fourth circuit 124 is connected in parallel to the sixth circuit 126, and the first circuit 121 is connected in parallel to the fifth circuit 125. By synchronizing the ON / OFF driving of the FETs of the fourth circuit 124 and the sixth circuit 126, only the fourth circuit 124 functions substantially, and in the forward driving, the FETs of the first circuit 121 and the fifth circuit 125 are turned ON. In the fourth embodiment, only the first circuit 121 is made to function substantially by synchronizing the off-driving. However, in the fourth embodiment, a switch element Q9 composed of an FET is connected in parallel to the resistor R, and this switch element Q9 The switching element of the first circuit 121 is formed by a series circuit with the switching element Q5 of the fifth circuit 125, and the switching element Q9 and the switching element Q6 of the sixth circuit 126 are connected directly. The switching element of the fourth circuit 124 is constituted by a column circuit.

Therefore, the drive circuit 12 ″ shown in FIG. 16 does not include the FETs (switch elements) constituting the first circuit 121 and the fourth circuit 124 in FIG. Are connected in parallel, the gate of this FET is connected to the control terminal C9 of the control circuit 10, and the on / off control is performed by the drive control signal Sc9.

The fourth embodiment has a higher F than the third embodiment.
Since the number of switch elements made of ET is reduced by one, the circuit configuration of the drive circuit can be further simplified.

FIG. 17 is a diagram showing the drive control signal of the drive circuit shown in FIG. 16 and the waveform of the charge / discharge voltage of the piezoelectric element.

In the same figure, the signal conversion operation of the logic circuit 127 in the fourth embodiment is the same as in Table 1 above, so the drive control signals Sc7, Sc8, Sp2, Sp3, Sp5, Sp6.
Are the same as those of the corresponding drive control signal in FIG. Further, since the switch element Q9 is a component of the first circuit 121 and the sixth circuit 126, the drive control signal Sc9 is operated by both the forward drive and the reverse drive, so that the drive control signal Sc9 of FIG. And the drive control signal Sc4.

In the fourth embodiment, in the reverse drive, the on / off control of the switch element Q9 is performed in synchronization with the on / off control of the switch element Q6 of the sixth circuit 126, whereby the fourth circuit 124 On / off control is performed (see the waveforms of the drive control signals Sc9 and Sp6 in FIG. 17). Also, in the forward drive, the first circuit 12 is turned on / off by performing the on / off control of the switch element Q9 in synchronization with the on / off control of the switch element Q5 of the fifth circuit 125.
1 is performed (see the waveforms of the drive control signals Sc9 and Sp5 in FIG. 17).

Therefore, the drive control signal Sc in FIG.
Since 9, Sp2, Sp3, Sp5, and Sp6 are substantially the same as the drive control signals Sc1, Sc4, Sp2, Sp3, Sp5, and Sp6 in FIG. 14, the piezoelectric element 3 is used in the fourth embodiment. The same control result as in the case of driving by the driving circuit 12 'according to the third embodiment can be obtained when driven by the driving circuit 12 ". The piezoelectric element 3, the driving member 4, and the driven member 5 can be obtained. Is the same as that in the case of being driven by the drive circuit 12 according to the first embodiment, and the description is omitted.

The portion constituted by the logic circuit 127 and the first to fourth circuits 121 to 124 in the third and fourth embodiments is the same as the H-bridge type circuit generally widely used for driving a DC motor. Configuration. Therefore,
By configuring that part with a general-purpose H-bridge IC, it is possible to further reduce the size and cost.

As described above, the charging / discharging current in the driving circuit 12 for the piezoelectric element 3 of the impact type piezoelectric actuator 1 is limited only by the resistor R, so that the driving circuit is smaller than the conventional one using a constant current circuit. Therefore, the size and cost of the piezoelectric actuator 1 can be reduced.

[0108]

As described above, according to the present invention,
A first drive circuit for applying a voltage in the polarization direction to the piezoelectric body;
A second drive circuit for applying a voltage to the piezoelectric body in a direction opposite to the polarization direction, and a drive control circuit for alternately driving the first drive circuit and the second drive circuit to expand and contract the piezoelectric body. In the drive device of the impact type piezoelectric actuator,
Since at least one of the first and second drive circuits is constituted by a current limiting circuit including only a resistor, the number of circuit elements of the drive device is reduced as compared with the case where a conventional constant current circuit is used. Therefore, the drive device can be simplified, downsized, and reduced in cost. Therefore, it is possible to realize an impact-type piezoelectric actuator that is suitable for portable equipment in which space and cost are important.

Also, in a driving device for an impact type piezoelectric actuator which can be driven in both forward and reverse directions using a bridge circuit, the current limiting circuit is constituted only by resistors, so that the bridge is formed with as few elements as possible. A circuit can be configured, and a drive device with high control performance can be realized at a compact size and at a low price.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of an embodiment of a piezoelectric actuator according to the present invention.

FIG. 2 is a cross-sectional view of a main part showing a mounting state of a contact member to a driving member in the electric actuator according to the present invention.

FIG. 3 is a block diagram showing a basic configuration of a drive circuit of an impact type piezoelectric actuator for moving in a forward direction.

FIG. 4 is a diagram illustrating an example of a specific circuit of a driving circuit of the piezoelectric member illustrated in FIG. 3;

5 is a diagram showing waveforms of a drive control signal of the drive circuit shown in FIG. 4 and a charge / discharge voltage of a piezoelectric member.

FIG. 6 is a diagram showing an example of a specific circuit of an impact type piezoelectric actuator for reverse driving.

FIG. 7 is a diagram illustrating an example of a specific circuit of a driving circuit of the piezoelectric member illustrated in FIG. 6;

8 is a diagram showing waveforms of a drive control signal of the drive circuit shown in FIG. 7 and a charge / discharge voltage of a piezoelectric member.

FIG. 9 is a diagram illustrating a basic configuration when a forward drive circuit and a reverse drive circuit are configured by a bridge circuit.

FIG. 10 is a diagram illustrating a first embodiment of a specific circuit configuration of a drive circuit using a bridge circuit.

11 is a diagram showing waveforms of a drive control signal of the drive circuit shown in FIG. 10 and a charge / discharge voltage of a piezoelectric member.

FIG. 12 is a diagram illustrating a second embodiment of a specific circuit configuration of a drive circuit using a bridge circuit.

13 is a diagram showing waveforms of a drive control signal of the drive circuit shown in FIG. 12 and a charge / discharge voltage of a piezoelectric member.

FIG. 14 is a diagram illustrating a third embodiment of a specific circuit configuration of a drive circuit using a bridge circuit.

15 is a diagram showing waveforms of a drive control signal of the drive circuit shown in FIG. 14 and a charge / discharge voltage of a piezoelectric member.

FIG. 16 is a diagram illustrating a fourth embodiment of a specific circuit configuration of a drive circuit using a bridge circuit.

17 is a diagram showing waveforms of a drive control signal of the drive circuit shown in FIG. 16 and a charge / discharge voltage of a piezoelectric member.

FIG. 18 is a view showing a schematic configuration of a conventional impact type piezoelectric actuator.

FIG. 19 is a first circuit example applied to a conventional low-speed charging circuit of a drive circuit for an impact type piezoelectric actuator.

FIG. 20 is a second circuit example applied to a conventional low-speed charging circuit of a drive circuit for an impact type piezoelectric actuator.

FIG. 21 is a circuit example applied to a low-speed discharge circuit of a drive circuit of a conventional impact type piezoelectric actuator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric actuator 2 Support member 201 Partition wall 202 1st accommodation space 203 2nd accommodation space 3 Piezoelectric member 4 Drive member 5 Driven member 501 Base 502 Ear 503 Nipping member 504 Hole 6,7 Leaf spring 8 Low speed charging circuit (First drive circuit) 9 High-speed discharge circuit (Second drive circuit) 10 Control circuit (Drive control circuit) 11 Power supply 12, 12 ', 12 "Bridge circuit (Drive circuit) 121 First circuit 122 Second circuit 123 Third circuit 124 Fourth circuit 125 Fifth circuit 126 Sixth circuit 127 Logic circuit (drive control circuit) Q1-Q6, Q9 Switch element (FET) R, R1, R2 Resistance

Claims (4)

[Claims] A first drive circuit for applying a voltage in a polarization direction to the piezoelectric body to extend the piezoelectric body; and a voltage in a direction opposite to the polarization direction to the piezoelectric body to reduce the piezoelectric body. A drive device for an impact-type piezoelectric actuator, comprising: a second drive circuit; and a drive control circuit that alternately drives the first drive circuit and the second drive circuit to expand and contract the piezoelectric body. A drive device for an impact-type piezoelectric actuator, wherein at least one of the first and second drive circuits is constituted by a current limiting circuit including only a resistor. 2. The driving apparatus for an impact type piezoelectric actuator according to claim 1, wherein the first driving circuit discharges electric charges accumulated in a direction opposite to a polarization direction of the piezoelectric body and charges the electric charges in a polarization direction. Wherein the second drive circuit comprises a second charge / discharge circuit which discharges the electric charge accumulated in the polarization direction of the piezoelectric body and charges the electric charge in a direction opposite to the polarization direction. A drive device for an impact type piezoelectric actuator. 3. A first circuit, a fourth circuit, and a fourth circuit, each of which is a series circuit of a switch circuit and a resistor, are connected to a first circuit, a fourth circuit, and a fourth circuit, respectively. And a power supply is connected between a connection point between the second circuit and the third circuit and a connection point between the first circuit and the fourth circuit, and the first circuit and the second circuit are connected to each other. And a bridge circuit in which a piezoelectric body is connected between the connection point of the third circuit and the connection point of the third circuit and the fourth circuit. The first drive circuit includes the power supply, the second circuit, and the fourth circuit. A circuit or the power supply, the second circuit and the sixth circuit, wherein the second drive circuit is the power supply, the third circuit and the fifth circuit or the power supply, the third circuit and the first circuit 3. The apparatus according to claim 2, wherein
A driving device for the impact-type piezoelectric actuator according to the above. 4. The driving device for an impact-type piezoelectric actuator according to claim 3, wherein said switch circuit comprises a field-effect transistor.