JP2012023924A - Piezoelectric actuator drive circuit and piezoelectric actuator device including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric actuator drive circuit capable of obtaining high energy efficiency.SOLUTION: A piezoelectric actuator drive circuit (3) includes a driving element drive circuit (8) for deforming a drive element (4a) in a vibrating manner and a driven element control circuit (10). The driven element control circuit includes a voltage source (22); a coil (28) of which a first terminal is connected to a driven element (4b); a unidirectional conduction element (24) for connecting between a second terminal of the coil and the power source and applying an electric current only to a power source direction from the second terminal of the coil; a switching element (26), connected between the second terminal of the coil and a ground potential, for switching between a conductive state and a non-conductive state by a control signal; and control signal generation circuits (32, 33) for generating the control signal to regenerate electric power in the power source from the second terminal of the coil by switching the switching element to the non-conductive state at a predetermined timing.

Description

  The present invention relates to a piezoelectric actuator drive circuit, and in particular, includes a plurality of polarization units, and in a predetermined drive state, a part of the plurality of polarization units functions as a drive element, and the other part includes the drive element. The present invention relates to a piezoelectric actuator drive circuit that drives a piezoelectric actuator that functions as a driven element that is deformed by being driven, and a piezoelectric actuator device including the piezoelectric actuator drive circuit.

  Piezoelectric actuators such as standing wave type ultrasonic motors (piezomotors) generally have a plurality of polarization portions formed in an integrated piezoelectric element, which are for normal rotation (for positive direction) and for reverse ( There is a polarization part for the reverse direction. When the actuator is rotated forward (driven in the forward direction), a pulse from a high-voltage power supply is supplied via a coil to cause the forward rotating (forward direction) polarization section to function as a drive element, and a driving force is generated. In addition, the inversion (reverse direction) polarization section functions as a driven element. On the other hand, when the actuator is reversed (reverse direction drive), a pulse from a high-voltage power supply is supplied via a coil to cause the reversal (reverse direction) polarization unit to function as a drive element, and a driving force is generated. In addition, the forward rotation (forward direction) polarization section functions as a driven element.

Japanese Patent Laying-Open No. 2007-143269 (Patent Document 1) describes a drive circuit and an imaging device using the drive circuit. In this drive circuit, one terminal of the polarization section functioning as a driven element is always open, so that no current flows from the polarization section functioning as the driven element.
Japanese Patent No. 3192828 (Patent Document 2) describes an ultrasonic motor. In this ultrasonic motor, the polarization part functioning as a driven element is always grounded via a coil.

JP 2007-143269 A Japanese Patent No. 3192028

  However, since the polarization section functioning as the driven element is deformed by driving the driving element, a voltage is generated at both ends of the driven element due to the piezoelectric effect. As in the drive circuit described in Japanese Patent Application Laid-Open No. 2007-143269, when the polarization unit functioning as a driven element is always open, power is not extracted from the polarization unit, and the voltage generated in the driven element is It cannot be used effectively. Further, the terminal voltage of the driven element, that is, the displacement amount of the driven element is not adjusted.

  In addition, as in the ultrasonic motor described in Japanese Patent No. 3192828, when a polarization part that functions as a driven element is grounded via a coil, an electromotive force generated in the polarization part flows to the ground via the coil. Therefore, the electromotive force generated by the driven element is consumed wastefully. Further, as a result of the current flowing to the ground, the terminal voltage of the driven element, that is, the displacement amount of the driven element is adjusted, but the improvement in driving efficiency is limited.

  As described above, in the conventional piezoelectric actuator drive circuit, deformation of the drive element is hindered by the driven element, or a part of the energy supplied to the drive element is wasted, resulting in a decrease in energy efficiency. There is a problem.

  Accordingly, an object of the present invention is to provide a piezoelectric actuator driving circuit capable of obtaining high energy efficiency and a piezoelectric actuator device including the piezoelectric actuator driving circuit.

  In order to solve the above-described problem, the present invention includes a plurality of polarization units, and in a predetermined driving state, a part of the plurality of polarization units functions as a drive element, and the other part includes a drive element. A piezoelectric actuator drive circuit that drives a piezoelectric actuator that functions as a driven element that is deformed by being driven, and is connected to the drive element and applies a drive voltage to the drive element based on the input drive signal, A driving element driving circuit for periodically deforming the driving element; and a driven element control circuit connected to the driven element. The driven element control circuit has a voltage source and a first terminal connected to the driven element. A coil, a unidirectional conducting element connected between the second terminal of the coil and the voltage source, and for passing a current only from the second terminal of the coil to the voltage source, and a second terminal of the coil Between ground potential A switching element connected and switched between a conductive state and a non-conductive state by a control signal, and a control for regenerating power from the second terminal of the coil to the voltage source by making the switching element non-conductive at a predetermined timing And a control signal generation circuit for generating a signal.

  In the present invention configured as described above, the drive element is periodically deformed by the drive element drive circuit based on the drive signal, and the driven element is also deformed accordingly. The driven element is connected to the driven element control circuit, and the power induced in the second terminal of the coil of the driven element control circuit due to the deformation of the driven element is switched to the non-conductive state at a predetermined timing. Thus, the voltage source is regenerated through the one-way conductive element.

  According to the present invention configured as described above, since the electric power induced in the second terminal of the coil is regenerated to the voltage source at a predetermined timing, it is possible to prevent the driven element from obstructing the driving of the driving element. The energy efficiency of driving the piezoelectric actuator can be improved.

In the present invention, preferably, the one-way conducting element is a diode.
According to the present invention configured as described above, the one-way conductive element can be configured at low cost.

  In the present invention, preferably, the unidirectional conducting element is constituted by an FET, and a parasitic diode between the drain terminal and the source terminal of the FET functions as the unidirectional conducting element.

  According to the present invention configured as described above, since the parasitic diode of the FET is used as the one-way conduction element, the same circuit can be configured as the driven element control circuit and the driving element by using the FET as the switching element. It can be used by switching to a drive circuit.

  In the present invention, preferably, the voltage source is a positive voltage source, and the switching element is in a conductive state from a conductive state at a predetermined timing within a period in which a current flows from the first terminal to the second terminal of the coil. Can be switched to.

In the present invention configured as described above, when the switching element is turned off, a positive voltage having the same polarity as that of the voltage source can be induced at the second terminal from the first terminal of the coil to the second terminal. When a current flows through the terminal, the switching element is switched to a non-conductive state. As a result, the electric power induced in the second terminal is regenerated to the positive voltage source through the one-way conducting element without flowing into the ground potential.
According to the present invention configured as described above, the power induced in the second terminal can be reliably regenerated in the voltage source.

  In the present invention, preferably, the voltage source is a negative voltage source, and the switching element is switched from the conductive state to the non-conductive state at a predetermined timing within a period in which current flows from the second terminal of the coil to the first terminal. Can be switched to.

In the present invention configured as described above, when the switching element is turned off, a negative voltage having the same polarity as that of the voltage source can be induced in the second terminal from the second terminal of the coil. When a current flows through the terminal, the switching element is switched to a non-conductive state. As a result, the electric power induced in the second terminal is regenerated to the negative voltage source through the one-way conducting element without flowing into the ground potential.
According to the present invention configured as described above, the power induced in the second terminal can be reliably regenerated in the voltage source.

  In the present invention, preferably, the switching element is constituted by an FET, and the control signal is input to the gate terminal of the FET, and the conduction state and non-conduction state between the drain terminal and the source terminal of the FET are switched.

  According to the present invention configured as described above, since the switching element is configured by the FET, a parasitic diode exists between the drain terminal and the source terminal even in the non-conduction state. For this reason, when the voltage of the second terminal has a polarity opposite to that of the voltage source, the voltage of the second terminal flows into the ground potential via the parasitic diode. Therefore, it is not necessary to switch the switching element to the conductive state at the timing when the voltage at the second terminal is opposite to the voltage of the voltage source, and it is possible to generate the control signal for the switching element with a simple circuit.

  In the present invention, preferably, the control signal generation circuit is configured to control the signal based on the drive signal input to the drive element drive circuit, the drive voltage signal applied to the drive element, or the first terminal voltage signal of the coil. Is generated.

  According to the present invention configured as described above, the control signal can be generated simply by adjusting the phase difference between the control signal and the drive signal, the drive voltage signal, or the first terminal voltage signal. can do.

  In addition, the piezoelectric actuator device of the present invention includes a rotor, a stator having a plurality of polarization units that drive the rotor, and a piezoelectric actuator drive circuit of the present invention that drives some drive elements of the plurality of polarization units. It is characterized by having.

  According to the piezoelectric actuator drive circuit of the present invention and the piezoelectric actuator device including the piezoelectric actuator drive circuit, high energy efficiency can be obtained.

1 is a block diagram showing an entire piezoelectric actuator device according to a first embodiment of the present invention. It is (a) circuit diagram explaining the effect | action of the drive element drive circuit built in the piezoelectric actuator drive circuit, and (b) timing chart. It is (a) circuit diagram explaining the effect | action of the driven element control circuit incorporated in the piezoelectric actuator drive circuit, and (b) timing chart. It is a block diagram which shows the whole piezoelectric actuator apparatus by 2nd Embodiment of this invention. It is (a) circuit diagram explaining the effect | action of the drive / control circuit incorporated in the piezoelectric actuator drive circuit, and (b) timing chart.

Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
First, a piezoelectric actuator device according to a first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a block diagram showing the entire piezoelectric actuator device according to the first embodiment of the present invention. FIG. 2 is a circuit diagram and a timing chart for explaining the operation of the drive element drive circuit built in the piezoelectric actuator drive circuit. FIG. 3 is a circuit diagram and timing chart for explaining the operation of the driven element control circuit built in the piezoelectric actuator drive circuit.

  As shown in FIG. 1, the piezoelectric actuator device 1 according to this embodiment includes a piezoelectric actuator 2 and a piezoelectric actuator drive circuit 3 that drives the piezoelectric actuator 2. The piezoelectric actuator device 1 of the present embodiment is configured such that the rotor 6 is rotated forward or reversely by driving a plurality of polarization units provided in the piezoelectric actuator 2 by the piezoelectric actuator drive circuit 3. .

  As shown in FIG. 1, the piezoelectric actuator 2 includes polarization portions 4 a and 4 b, a friction member 5, and a rotor 6. The piezoelectric actuator drive circuit 3 includes a drive element drive circuit 8, a driven element control circuit 10, and forward / reverse changeover switches 11a and 11b.

  The polarization parts 4a and 4b are formed in a single piezoelectric characteristic member, and either one functions as a driving element and the other functions as a driven element. In the present embodiment, the polarization portions 4a and 4b are attached to a single piezoelectric characteristic member 4c formed in a rectangular parallelepiped shape, a ground electrode 4d attached to one surface thereof, and an opposite side of the ground electrode 4d. 4 electrodes 4e, 4f, 4g and 4h. The ground electrode 4d is attached to the piezoelectric characteristic member 4c so as to cover the entire surface of the piezoelectric characteristic member 4c, and is connected to the ground potential. Four electrodes 4e, 4f, 4g, and 4h are mounted side by side on the surface of the piezoelectric characteristic member 4c opposite to the ground electrode 4d. In FIG. 1, the electrode 4e arranged at the upper left and the electrode 4h arranged at the lower right are electrically connected, and the electrode 4f arranged at the upper right and the electrode 4g arranged at the lower left are electrically connected. It is connected to the. Thereby, the upper right part and the lower left part of the piezoelectric characteristic member 4c in FIG. 1 where the electrodes 4f and 4g are arranged function as the polarization part 4a, and the upper left part and the lower right part where the electrodes 4e and 4h are arranged are It functions as the polarization part 4b. In this specification, a configuration in which a part of the polarization portion formed in a single piezoelectric characteristic member acts as a driving element and the other part acts as a driven element as in the present embodiment. It will be called “a plurality of elements” or polarization portions.

  In the state shown in FIG. 1, the polarization unit 4 a connected to the drive element drive circuit 8, that is, the upper right part and the lower left part in FIG. 1 of the piezoelectric characteristic member 4 c act as drive elements, and the driven element control circuit 10 The connected polarization part 4b, that is, the upper left part and the lower right part of the piezoelectric characteristic member 4c act as driven elements. In addition, when each polarization unit functions as a drive element, it is configured to be deformed by applying an alternating voltage in the ultrasonic band from the drive element drive circuit 8 and to be ultrasonically vibrated. On the other hand, each polarization part is configured to be deformed together with the deformation of the drive element when acting as a driven element. In the present embodiment, the piezoelectric actuator 2 includes only the polarization portions 4a and 4b. However, the piezoelectric actuator drive circuit of the present invention can also be applied to a piezoelectric actuator including a large number of sets of polarization portions. .

  The friction member 5 is a protrusion pressurized against the rotor 6, and is configured to vibrate together with the vibration of the piezoelectric characteristic member. When the friction member 5 is vibrated, the rotor 6 pressed against the friction member 5 rotates in a predetermined direction.

  The forward / reverse changeover switch 11a is connected between the drive element drive circuit 8 and the polarization units 4a and 4b so that the output voltage of the drive element drive circuit 8 is applied to either the polarization unit 4a or 4b. Can be switched. The forward / reverse changeover switch 11b is connected between the driven element control circuit 10 and the polarization units 4a and 4b so that the output voltage of the driven element control circuit 10 is connected to either the polarization unit 4a or 4b. Can be switched. In the present embodiment, as shown in FIG. 1, when the output of the drive element drive circuit 8 is applied to the polarization unit 4a and the polarization unit 4b is switched to be connected to the driven element control circuit 10, the rotor 6 is positive. It is rolled. Conversely, when the output of the drive element drive circuit 8 is applied to the polarization unit 4b and the polarization unit 4a is switched to be connected to the driven element control circuit 10, the rotor 6 is inverted.

  The drive element drive circuit 8 includes a switching element control circuit 12, a high voltage power supply 14 that is a voltage source, a drive high side switching element 16, a drive low side switching element 18, and a drive coil 20.

  The switching element control circuit 12 is configured to switch the driving high-side switching element 16 and the driving low-side switching element 18 to a conductive state or a non-conductive state based on the ultrasonic band drive signal and the enable signal. . Specifically, the switching element control circuit 12 can be configured by various logic ICs or the like.

  The high-voltage power supply 14 is a voltage source that generates a positive high voltage, and is connected to the driving high-side switching element 16. When the driving high-side switching element 16 is switched to the conductive state, a high voltage is applied to the driving element via the driving coil 20.

  In the present embodiment, the driving high-side switching element 16 is configured by an N-channel MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), the gate terminal of which is connected to the switching element control circuit 12, and the drain The terminal is connected to the high voltage power source 14 and the source terminal is connected to the drive coil 20.

  In the present embodiment, the driving low-side switching element 18 is configured by an N-channel MOSFET, and has a gate terminal connected to the switching element control circuit 12, a drain terminal connected to the drive coil 20, and a source terminal. Is grounded.

  The drive coil 20 is connected to the polarization unit 4a or 4b functioning as a drive element via the drive terminal 20a which is the first terminal, and the second terminal 20b is connected to the drive high-side switching element 16 as described above. And the drain terminal of the driving low-side switching element 18. Here, the polarization section 4a or 4b connected to the drive coil 20 acts as an LC resonance circuit, and the drive coil 20 has an appropriate high voltage generated at the drive terminal 20a in the vicinity of the resonance frequency of the piezoelectric actuator 2. The inductance value is selected.

  The driven element control circuit 10 includes a high voltage power source 22 that is a voltage source, a diode 24 that is a one-way conduction element, a driven low-side switching element 26 that is a switching element, a driven coil 28, a comparator 30, and a phase shifter 32. And having. In the present embodiment, the comparator 30 and the phase shifter 32 function as a control signal generation circuit.

  The high-voltage power supply 22 is a voltage source that generates a positive high voltage, and is connected to the cathode side of the diode 24. In FIG. 1, the high-voltage power supply 14 and the high-voltage power supply 22 are illustrated separately, but they are actually composed of the same high-voltage power supply. That is, the cathode of the diode 24 and the drain terminal of the driving high-side switching element 16 are connected to the same voltage source.

The diode 24 has a cathode connected to the high voltage power source 22 and an anode connected to the driven low-side switching element 26 and the driven coil 28.
In this embodiment, the driven low-side switching element 26 is composed of an N-channel type MOSFET, the gate terminal of which is connected to the output terminal of the phase shifter 32, the drain terminal of which is the anode of the diode 24 and the driven coil 20. The source terminal is grounded.

  The driven coil 28 is connected to the polarization unit 4a or 4b functioning as a driven element via a driven terminal 28a that is the first terminal, and the second terminal 28b is connected to the anode of the diode 24, and The driven low side switching element 26 is connected to the drain terminal.

  The comparator 30 is configured to receive a voltage signal from the driven terminal 28a, compare the voltage signal with a predetermined voltage value, and output a high level signal or a low level signal to the phase shifter 32. Thereby, the voltage signal of the driven terminal 28a is converted into a digital signal binarized to a high level or a low level.

  The phase shifter 32 is configured to output the pulsed digital signal input from the comparator 30 with a predetermined time delay, and to shift the phase of the input signal by a predetermined amount. The output signal of the phase shifter 32 is connected to the gate terminal of the driven low-side switching element 26 as a control signal, and is configured to switch between the conductive state and non-conductive state of the driven low-side switching element 26. Specifically, the phase shifter 32 includes a logic IC, an operational amplifier, an electric resistor, a capacitor, and the like.

  Next, the operation of the drive element drive circuit 8 incorporated in the piezoelectric actuator drive circuit 3 will be described with reference to FIG. FIG. 2A shows the drive element drive circuit 8, and FIG. 2B is a timing chart showing the operation of the drive element drive circuit 8. In the timing chart of FIG. 2B, the drive signal, the enable signal, the state of the driving high-side switching element 16, the state of the driving low-side switching element 18, and the voltage of the second terminal 20b of the driving coil 20 are shown in order from the top. Show.

  First, the switching element control circuit 12 receives a rectangular-wave drive signal shown in the upper part of FIG. The drive signal is selected to have a frequency close to the resonance frequency of the piezoelectric actuator 2, and an appropriate high voltage is generated at the drive terminal 20a. The enable signal at the second stage in FIG. 2B is a signal for setting the operation / non-operation of the switching element control circuit 12, and is always set to the H level when the piezoelectric actuator drive circuit 3 is operated. When the enable signal is set to L level, the driving high-side switching element 16 and the driving low-side switching element 18 are always in a non-conductive state regardless of the driving signal.

  As shown in FIG. 2B, when the drive signal is at the L level, the switching element control circuit 12 turns off the driving high-side switching element 16 and turns on the driving low-side switching element 18. Set to the state (ON). Specifically, the switching element control circuit 12 sends a signal to each gate terminal of the driving high side switching element 16 and the driving low side switching element 18 to switch these FETs on and off. When the driving high-side switching element 16 is turned off and the driving low-side switching element 18 is turned on, the second terminal 20b of the driving coil 20 is grounded via the driving low-side switching element 18, and thus becomes 0V. .

  Next, when the driving signal rises from the L level to the H level, the driving low-side switching element 18 is immediately turned off, and the driving high-side switching element 16 is switched on after a predetermined dead time (Dead-Time) T1 has elapsed. , Switched on. When the driving low-side switching element 18 is switched off and the driving high-side switching element 16 is switched on, the second terminal 20b of the driving coil 20 is connected to the high-voltage power supply 14 via the driving high-side switching element 16, and The terminal voltage of the second terminal 20 b rises to the voltage of the high-voltage power supply 14.

  Note that both the drive low side switching element 18 and the drive high side switching element 16 are turned off during the dead time T1 after the drive low side switching element 18 is turned off until the drive high side switching element 16 is turned on. By providing such dead time T1, a short circuit between the high-voltage power supply 14 and the ground potential is prevented. During this dead time T1 (the hatched portion in FIG. 2B), the second terminal 20b of the drive coil 20 is in a high impedance state, and the voltage of the second terminal 20b is equal to the potential of the drive terminal 20a and the drive coil. The value depends on the current direction and the current value.

  Subsequently, when the drive signal falls from the H level to the L level, the drive high side switching element 16 is immediately switched off, and the drive low side switching element 18 is switched on after a predetermined dead time T1 has elapsed. It is done. When the driving high-side switching element 16 is turned off and the driving low-side switching element 18 is turned on, the second terminal 20b of the driving coil 20 is grounded via the driving low-side switching element 18, so that it becomes 0V again. Become.

  By repeating the above operation, a pulse voltage is applied to the drive coil 20. This pulsed voltage resonates with the inductance of the drive coil 20 and the capacitive component of the drive element (capacitance component of the polarization unit 4a in the state shown in FIG. 1), whereby a pulsed high voltage is applied to the drive element. Is deformed in a vibrational manner.

  Next, the operation of the driven element control circuit 10 built in the piezoelectric actuator drive circuit 3 will be described with reference to FIG. FIG. 3A shows the driven element control circuit 10, and FIG. 3B is a timing chart showing the operation of the driven element control circuit 10. In the timing chart of FIG. 3B, the voltage VL of the second terminal 28 b of the driven coil 28, the control signal for controlling the driven low-side switching element 26, the current IL flowing through the driven coil 28, the driven coil 28, in order from the top. The voltage Vf of the driven terminal 28a which is the first terminal is shown.

  When the drive element (the polarization part 4a in the state of FIG. 1) is deformed by the drive voltage, the driven element (the polarization part 4b in the state of FIG. 1) is also deformed accordingly. Due to this deformation, the driven element generates an electromotive force. This electromotive force generates a vibrating voltage at the driven terminal 28 a and a current flows through the driven coil 28.

  First, when the current IL flowing through the driven coil 28 is in the positive direction (the direction from the second terminal 28b of the driven coil 28 to the driven terminal 28a), the second terminal 28b of the driven coil 28 has a negative high voltage. Voltage is generated. Conversely, when the current IL flowing through the driven coil 28 is in the negative direction (the direction from the driven terminal 28a of the driven coil 28 toward the second terminal 28b), the second terminal 28b of the driven coil 28 has a positive value. High voltage is generated.

  At time t0 to t1 in FIG. 3B, since the current IL is positive, a negative high voltage can appear at the second terminal 28b. However, since the control signal is at the H level at time t0 to t1, the driven low-side switching element 26 is in a conductive state (ON), and the second terminal 28b is grounded via the driven low-side switching element 26. Therefore, the voltage VL of the second terminal 28b is maintained at 0V. In addition, since the current IL is negative from time t1 to time t2, a positive high voltage may appear at the second terminal 28b. However, since the driven low-side switching element 26 is also on during this period, The voltage VL at the terminal 28b is maintained at 0V.

  Next, when the control signal is changed to the L level at time t2, the driven low-side switching element 26 is switched to the non-conduction state (off), so that the positive high voltage appearing at the second terminal 28b is grounded. Without flowing, it is regenerated to the high-voltage power supply 22 via the diode 24 (time t2 to t3).

  Further, at time t3, the current IL changes from negative to positive, and a negative high voltage can be generated at the second terminal 28b. However, a parasitic diode (illustrated by a broken line) is formed between the drain terminal and the source terminal of the MOSFET that is the driven low-side switching element 26, with the source side serving as an anode and the drain side serving as a cathode. For this reason, the negative voltage appearing at the second terminal 28b flows to the ground via the parasitic diode of the driven low-side switching element 26, and the voltage VL at the second terminal 28b becomes 0V (FIG. 3B). Time t3).

  That is, at time t3, the control signal is still at the L level, and the driven low-side switching element 26 is kept off, but the negative voltage generated at the second terminal 28b is the driven low-side switching element 26. Is grounded by a parasitic diode. For this reason, when an FET having a parasitic diode is used as the driven low-side switching element 26, the control is performed when the current flowing through the driven coil 28 changes from negative to positive (time t3 in FIG. 3B). The second terminal 28b can be grounded without switching the signal to the H level.

  Next, at time t4, the control signal is switched to the H level, and the driven low-side switching element 26 is turned on. As a result, the second terminal 28b is grounded. However, as described above, since the negative voltage generated at the second terminal 28b is already grounded by the parasitic diode of the driven low-side switching element 26, the timing at which the control signal is switched to the H level is the current IL. Any time can be set as long as it is before time t5 when it changes negative again. That is, in the present embodiment, the timing for switching the control signal to the H level can be set to any timing between time t3 and time t5.

  In the present embodiment, the control signal input to the driven low-side switching element 26 is generated by the comparator 30 and the phase shifter 32 based on the voltage generated at the driven terminal 28a. First, the voltage signal of the driven terminal 28a is converted by the comparator 30 into a pulsed digital signal that takes a value of H level or L level. The control signal can be generated by adjusting the phase by delaying the pulse-like signal output from the comparator 30 by the phase shifter 32 for a predetermined time.

  The phase relationship between the drive signal input to the drive element drive circuit 8, the voltage signal generated at the drive terminal 20a, and the voltage signal generated at the driven terminal 28a slightly moves depending on the state of the rotational speed and load torque. Therefore, by appropriately setting the delay time by the phase shifter 32, an appropriate signal may be selected from these signals so as to obtain desired motor characteristics, and a control signal may be generated.

  By repeating the above operation, the voltage Vf of the driven terminal 28a, which is the first terminal of the driven coil 28, is periodically changed as shown in the lowest stage of FIG. By changing the voltage Vf of the driven terminal 28a in this way, the driven element (the polarization part 4b in the state of FIG. 1) prevents the vibrational deformation of the drive element (the polarization part 4a in the state of FIG. 1). And the energy efficiency of the piezoelectric actuator 2 is improved.

  The waveform of the voltage Vf at the driven terminal 28a indicates the timing at which the driven low-side switching element 26 is switched to the non-conductive state (off) during the period (time t1 to t3) in which the current IL flowing through the driven coil 28 is negative. It changes depending on (time t2 in FIG. 3). The optimum switching timing for improving the energy efficiency varies depending on the characteristics of the driven piezoelectric actuator 2, but the energy efficiency can be improved by turning off the driven low-side switching element 26 at an appropriate timing. In the present embodiment, the driven low-side switching element 26 has a timing (time t2 in FIG. 3) when the voltage of the driven terminal 28a changes from positive to negative when the current of the driven coil 28 has a negative maximum value. By turning off, we have succeeded in improving energy efficiency. Preferably, from the point at which the voltage at the driven terminal 28a (the first terminal of the driven coil 28) changes from positive to negative (time t2 in FIG. 3), near the point at which the voltage at the driven terminal 28a changes from negative to positive ( In the period of time t4) in FIG. 3, the driven low-side switching element is turned off.

  According to the piezoelectric actuator device of the first embodiment of the present invention, the electric power induced in the second terminal 28b of the driven coil 28 is regenerated to the high voltage power source 22 at a predetermined timing, and as a result, the driven element (FIG. The terminal voltage of the polarization unit 4b) in the state 1, that is, the displacement amount of the driven element can be adjusted, and the driven element can be prevented from obstructing the drive of the drive element (the polarization unit 4a in the state of FIG. 1), The energy efficiency for driving the piezoelectric actuator 2 can be improved.

  In addition, according to the piezoelectric actuator device of the first embodiment of the present invention, the diode 24 is used as a one-way conduction element, and power is regenerated to the high-voltage power supply 22 through the diode 24. It can be configured at low cost.

  Furthermore, according to the piezoelectric actuator device of the first embodiment of the present invention, the driven low is applied during a period in which the current of the driven coil 28 is negative (current is flowing from the first terminal to the second terminal). The side switching element 26 is switched to a non-conductive state (off). As a result, electric power is induced in the second terminal 28 b and can be reliably regenerated by the high-voltage power supply 22 through the diode 24.

  Further, according to the piezoelectric actuator device of the first embodiment of the present invention, since the driven low-side switching element 26 is configured by a MOSFET, a parasitic diode is provided between the drain terminal and the source terminal even in the non-conduction state (off). Exists. For this reason, when the voltage of the second terminal 28b becomes a negative voltage having a polarity opposite to that of the high-voltage power supply 22, the voltage of the second terminal 28b flows into the ground potential via the parasitic diode. Therefore, it is not necessary to switch the driven low-side switching element 26 to the conductive state at the timing when the voltage of the second terminal 28b becomes a negative voltage having a polarity opposite to that of the high-voltage power supply 22. Therefore, when the control signal for the driven low-side switching element 26 is generated based on the potential of the first terminal 28a of the driven coil 28, the driven low-side switching element 26 is adjusted when the delay time of the comparator 30 is adjusted by the phase shifter. As long as the timing of turning on the driven low-side switching element 26 matches the timing at which the potential of the first terminal 28a of the driven coil 28 is switched from positive to negative, the timing at which the driven low-side switching element 26 is turned on is positive. It is not always necessary to match the timing of switching to. This makes it possible to generate a control signal for the driven low-side switching element 26 with a simple circuit.

  Furthermore, according to the piezoelectric actuator device of the first embodiment of the present invention, the control signal is generated based on the voltage waveform signal generated in the driven element, so the voltage waveform of the driven terminal is digitized by the comparator 30. The control signal can be generated simply by adjusting the phase difference with the phase shifter 32.

  In the first embodiment of the present invention described above, when a positive voltage source is used as the high-voltage power supply 14 and a current flows from the first terminal of the driven coil 28 to the second terminal, the driven low side The switching element was switched off and power was regenerated in the high-voltage power supply 14. As a modification, when a negative voltage source is used for the high-voltage power supply and a current flows from the second terminal of the driven coil 28 to the first terminal, the driven low-side switching element is switched off to supply power to the high-voltage power supply. It can also be regenerated. That is, when a current flows from the second terminal of the driven coil 28 to the first terminal, a negative voltage is generated at the second terminal by switching off the driven low-side switching element. It is possible to regenerate power in the voltage source.

Next, a piezoelectric actuator device according to a second embodiment of the present invention will be described with reference to FIGS. The piezoelectric actuator device of this embodiment is different from the first embodiment described above in the configuration of the piezoelectric actuator drive circuit. Accordingly, here, only the points of the present embodiment that are different from the first embodiment will be described, and description of similar points will be omitted.
FIG. 4 is a block diagram showing the entire piezoelectric actuator device according to the second embodiment of the present invention. FIG. 5 is a circuit diagram and timing chart for explaining the operation of the drive / control circuit built in the piezoelectric actuator drive circuit.

  As shown in FIG. 4, the piezoelectric actuator drive circuit 103 provided in the piezoelectric actuator device 100 of this embodiment includes two drive / control circuits 108 and 110. In the first embodiment described above, the drive element drive circuit 8 is always connected to the polarization section that acts as the drive element, and the driven element control circuit 10 is always connected to the polarization section that acts as the driven element. On the other hand, in the present embodiment, the drive / control circuit 108 is always connected to the polarization unit 4b, and the drive / control circuit 110 is always connected to the polarization unit 4a. Here, the drive / control circuit 110 functions as a drive element drive circuit when the polarization unit 4a functions as a drive element, and functions as a driven element control circuit when the polarization unit 4a functions as a driven element. Similarly, the drive / control circuit 108 functions as a drive element drive circuit when the polarization unit 4b functions as a drive element, and functions as a driven element control circuit when the polarization unit 4b functions as a driven element.

  As shown in FIG. 4, the drive / control circuit 108 includes a switching element control circuit 112, a drive / control changeover switch 113, a high voltage power source 114 that is a voltage source, an H level signal source 115, and a high side switching element 116. A low-side switching element 118, a coil 120, a comparator 119, and a phase shifter 121. Similarly, the drive / control circuit 110 includes a switching element control circuit 123, a drive / control changeover switch 125, a high voltage power source 122 as a voltage source, an H level signal source 127, a high side switching element 124, and a low side. A switching element 126, a coil 128, a comparator 130, and a phase shifter 132 are included. The drive / control circuit 108 and the drive / control circuit 110 have the same configuration, and function as a drive element drive circuit or a driven element control circuit by switching the circuits.

  Further, the piezoelectric actuator drive circuit 103 includes a changeover switch 111 connected between a signal source (not shown) of a drive signal and the drive / control circuits 108 and 110. In the present embodiment, the drive / control circuit to which the drive signal is input by the changeover switch 111 functions as a drive element drive circuit, and the other drive / control circuit functions as a driven element control circuit. In the state shown in FIG. 4, the drive signal is input to the drive / control circuit 108, the H level signal source 115 is connected to the switching element control circuit 112, and the phase shifter 132 is connected to the switching element control circuit 123. ing. In this state, the drive / control circuit 108 functions as a drive element drive circuit, and the drive / control circuit 110 functions as a driven element control circuit. In the state where the drive signal is input to the drive / control circuit 110, the H level signal source 127 is connected to the switching element control circuit 123, and the phase shifter 121 is connected to the switching element control circuit 112, the drive / control circuit. Reference numeral 108 functions as a driven element control circuit, and the drive / control circuit 110 functions as a drive element drive circuit.

  The configuration of the drive / control circuits 108 and 110 in the present embodiment is substantially the same as that of the driven element control circuit 10 in the first embodiment. In the driven element control circuit 10 of the first embodiment, the diode 24 is connected between the high voltage power supply 22 and the driven low-side switching element 26, whereas in the present embodiment, the high voltage of the drive / control circuit 108 is connected. A MOSFET is connected as a high-side switching element 116 between the power supply 114 and the low-side switching element 118.

  Next, the operation of the drive / control circuit 108 built in the piezoelectric actuator drive circuit 103 will be described with reference to FIG. FIG. 5A shows the drive / control circuit 108, and FIG. 5B is a timing chart showing the operation of the drive / control circuit 108. The timing chart of FIG. 5B shows, in order from the top, the drive signal, the enable signal, the state of the drive high-side switching element 116, the state of the drive low-side switching element 118, and the voltage of the second terminal 120b of the coil 120. ing. The first half of the timing chart of FIG. 5B shows the operation when the drive / control circuit 108 functions as a drive element drive circuit, and the second half of the timing chart shows the drive / control circuit 108 as a driven element control circuit. It shows the effect when it works.

  First, the switching element control circuit 112 receives a rectangular-wave drive signal shown in the upper part of FIG. The enable signal at the second stage in FIG. 5B is a signal for setting the operating state of the switching element control circuit 112. When the drive / control circuit 108 functions as a drive element drive circuit, it is always set to the H level. Is done. As will be described later, when the drive / control circuit 108 functions as a driven element control circuit, the output signal of the phase shifter 121 is input to the switching element control circuit 112 as an enable signal.

  As shown in the first half of FIG. 5B, when the drive / control circuit 108 functions as a drive element drive circuit, a drive signal is input to the switching element control circuit 112 and an H level signal source 115 is provided. Therefore, an H level signal is always input as an enable signal. Thereby, the high-side switching element 116 and the low-side switching element 118 are controlled in the same manner as the driving high-side switching element 16 and the driving low-side switching element 18 in the first embodiment, and the driving element is driven via the coil 120. The

  Further, as shown in the latter half of FIG. 5B, when the drive / control circuit 108 functions as a driven element control circuit, no drive signal is input to the switching element control circuit 112 (at L level). In addition, the output signal of the phase shifter 121 is input as an enable signal.

First, the high-side switching element 116 is maintained in the non-conduction state (off) by maintaining the drive signal at the L level. On the other hand, the low-side switching element 118 is switched to the conductive state (ON) while the enable signal is at the H level, and is switched to the non-conductive state (OFF) when the enable signal is at the L level. While both the high-side switching element 116 and the low-side switching element 118 are switched to the non-conductive state, the second terminal 120b of the coil 120 is in a high impedance state, and the voltage of the second terminal 120b is The value depends on the potential of the terminal 120a, the current direction of the coil 120, and the current value.
Note that while the enable signal is at the L level, the high-side switching element 116 and the low-side switching element 118 are always in a non-conductive state regardless of the drive signal. Therefore, even if a drive signal as indicated by a broken line is applied to the latter half of FIG. 5B, the high-side switching element 116 is maintained in a non-conductive state.

  Here, a parasitic diode (illustrated by a broken line) is formed between the drain terminal and the source terminal of the MOSFET constituting the high-side switching element 116, with the source side serving as an anode and the drain side serving as a cathode. For this reason, by maintaining the high-side switching element 116, which is a MOSFET, in the off state, the high-side switching element 116 functions in the same manner as the diode 24 in the first embodiment. Therefore, when the drive / control circuit 108 functions as a driven element control circuit, the high-side switching element 116 is always turned off as described above. As described above, the enable signal is input as a control signal to the switching element control circuit 112 via the comparator 119 and the phase shifter 121. As a result, a positive high voltage appearing at the second terminal 120b of the coil 120 is applied to the high-voltage power supply 114 during a part of the period when the low-side switching element 118 is turned on and off and the low-side switching element 118 is turned off. It is regenerated. In this way, the drive / control circuit 108 can function in the same manner as the driven element control circuit 10 in the first embodiment.

  Similarly, in the drive / control circuit 110, a MOSFET is connected as the high-side switching element 124 between the high-voltage power supply 122 and the low-side switching element 126. When the drive / control circuit 110 functions as a driven element control circuit, the high-side switching element 124 is always kept off, and the switching element control circuit 123 receives a control signal via the comparator 130 and the phase shifter 132. Is entered. When the drive / control circuit 110 functions as a drive element drive circuit, a drive signal is input to the switching element control circuit 123 and an H level signal is always input from the H level signal source 127 as an enable signal. The

  In this embodiment, the control signal is a voltage waveform at the driven terminal (voltage waveform at the first terminals 120a and 128a of the coil when the drive / control circuit 108 or 110 functions as a driven element control circuit). Is generated based on As described above, the control signal appropriately sets the delay time in the phase shifter so that desired motor characteristics can be obtained, so that the drive signal or the voltage waveform of the drive terminal (the drive / control circuit 108 is the drive element drive circuit). May be generated from the voltage waveform of the first terminal 120a when it functions as a voltage waveform of the first terminal 128a when the drive / control circuit 110 functions as a drive element drive circuit.

  According to the piezoelectric actuator device 100 of the second embodiment of the present invention, the parasitic diode of the MOSFET is used as the one-way conduction element. Therefore, by using this MOSFET as the high-side switching elements 116 and 124, the same The drive / control circuits 108 and 110 can be switched between a driven element control circuit and a drive element drive circuit.

  As mentioned above, although preferable embodiment of this invention was described, a various change can be added to embodiment mentioned above. In particular, in the above-described embodiment, the piezoelectric actuator drive circuit is used to drive the piezoelectric actuator that drives the rotor. However, the piezoelectric actuator drive circuit of the present invention can be used for any piezoelectric actuator such as a linear actuator. It can be applied to driving.

In the above-described embodiment, the piezoelectric actuator drive circuit is configured to be capable of normal rotation and reverse drive. However, the present invention can also be applied to a piezoelectric actuator drive circuit capable of driving in only one direction. .
Further, in addition to the piezoelectric actuator shown in FIG. 1 or FIG. 4, if it has a plurality of polarization parts, it can be applied to drive a piezoelectric actuator of any lamination method, any polarization method, any wiring method. Can do.

  Furthermore, in the above-described embodiment, the drive element is driven using a positive high-voltage power supply, but a negative high-voltage power supply can also be used as the high-voltage power supply. In the above-described embodiment, the N-channel MOSFET is used as the switching element. However, in consideration of the polarity of the high-voltage power supply, a P-channel MOSFET can be used as the switching element.

DESCRIPTION OF SYMBOLS 1 Piezoelectric actuator apparatus 2 Piezoelectric actuator 3 Piezoelectric actuator drive circuit 4a, 4b Polarization part (drive element, driven element)
DESCRIPTION OF SYMBOLS 5 Friction member 6 Rotor 8 Drive element drive circuit 10 Driven element control circuit 11a, 11b Forward / reverse changeover switch 12 Switching element control circuit 14 High voltage power supply (voltage source)
16 driving high-side switching element 18 driving low-side switching element 20 driving coil 20a driving terminal 20b second terminal 22 high voltage power supply (voltage source)
24 diode (unidirectional conducting element)
26 driven low side switching element 28 driven coil (coil)
28a Follower terminal (first terminal)
28b Second terminal 30 Comparator (control signal generation circuit)
32 Phase shifter (control signal generation circuit)
DESCRIPTION OF SYMBOLS 100 Piezoelectric actuator apparatus of 2nd Embodiment of this invention 103 Piezoelectric actuator drive circuit 108 Drive / control circuit 110 Drive / control circuit 111 Changeover switch 112 Switching element control circuit 113 Drive / control changeover switch 114 High voltage power supply (voltage source)
115 H-level signal source 116 High-side switching element (unidirectional conducting element)
118 Low-side switching element 119 Comparator (control signal generation circuit)
120 coil
120a first terminal 121 phase shifter (control signal generation circuit)
123 Switching element control circuit 122 High voltage power supply (voltage source)
124 High-side switching element (unidirectional conducting element)
125 drive / control changeover switch 126 low-side switching element 127 H level signal source 128 coil (coil)
128a First terminal 130 Comparator (control signal generation circuit)
132 Phase shifter (control signal generation circuit)

Claims (8)

As a driven element that includes a plurality of polarization sections, and in a predetermined driving state, a part of the plurality of polarization sections functions as a drive element and the other part is deformed by driving the drive element. A piezoelectric actuator drive circuit for driving a functioning piezoelectric actuator,
A driving element driving circuit that is connected to the driving element and applies a driving voltage to the driving element based on an input driving signal to periodically deform the driving element;
A driven element control circuit connected to the driven element,
The driven element control circuit is
A voltage source;
A coil having a first terminal connected to the driven element;
A unidirectional conducting element connected between the second terminal of the coil and the voltage source, and for passing a current only from the second terminal of the coil in the direction of the voltage source;
A switching element connected between the second terminal of the coil and the ground potential and switched between a conductive state and a non-conductive state by a control signal;
A control signal generating circuit for generating a control signal for regenerating power from the second terminal of the coil to the voltage source by making the switching element non-conductive at a predetermined timing;
A piezoelectric actuator drive circuit comprising:   The piezoelectric actuator drive circuit according to claim 1, wherein the one-way conducting element is a diode.   2. The piezoelectric actuator drive circuit according to claim 1, wherein the one-way conducting element is constituted by an FET, and a parasitic diode between a drain terminal and a source terminal of the FET functions as the one-way conducting element.   The voltage source is a positive voltage source, and the switching element is switched from a conduction state to a non-conduction state at a predetermined timing within a period in which a current flows from the first terminal to the second terminal of the coil. Item 4. The piezoelectric actuator drive circuit according to any one of Items 1 to 3.   The voltage source is a negative voltage source, and the switching element is switched from a conductive state to a non-conductive state at a predetermined timing within a period in which a current flows from the second terminal of the coil to the first terminal. Item 4. The piezoelectric actuator drive circuit according to any one of Items 1 to 3.   5. The switching element according to claim 1, wherein the switching element is configured by an FET, and the control signal is input to a gate terminal of the FET to switch between a conductive state and a non-conductive state between the drain terminal and the source terminal of the FET. A piezoelectric actuator drive circuit according to 1.   The control signal generation circuit is configured to control the control signal based on the drive signal input to the drive element drive circuit, the drive voltage signal applied to the drive element, or the first terminal voltage signal of the coil. The piezoelectric actuator drive circuit according to any one of claims 1 to 5, wherein: With the rotor,
A stator having a plurality of polarization portions for driving the rotor;
The piezoelectric actuator drive circuit according to any one of claims 1 to 6, which drives some drive elements of the plurality of polarization units,
A piezoelectric actuator device comprising:

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