JP2006109679A - Ultrasonic actuator device and method of driving ultrasonic actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic actuator driving unit which is possible of precise drive control capable of getting an accurate stop position by reducing the burden to a drive mechanism within an actuator, in simple constitution, and a method of driving the actuator. <P>SOLUTION: This ultrasonic actuator driving unit 1 is equipped with a controller 2, a driver 3, first and second vibration information detectors 4 and 6, and an ultrasonic actuator 5 which has an ultrasonic oscillator 5A and a driven body 5B. The above controller 2 controls the driving force to the above driven body 5B to change gradually by switching the oscillation state ( for example, the three oscillation modes of a bending oscillation mode, a elliptic oscillation mode, and a no-feed mode) of the above ultrasonic oscillator 5A, when starting or stopping the above driven body 5B. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ultrasonic actuator driving apparatus and an ultrasonic actuator driving method, and in particular, drives driving control such as stopping of an ultrasonic actuator by controlling an AC voltage drive signal applied to an ultrasonic transducer of the ultrasonic actuator. The present invention relates to an ultrasonic actuator driving apparatus and an ultrasonic actuator driving method that can be performed accurately without applying a load to a mechanism.

Conventionally, many proposals have been made regarding ultrasonic actuators having many advantages over electromagnetic motors.
For example, the proposal disclosed in Japanese Patent Laid-Open No. 7-163162 relates to an ultrasonic actuator that generates an ultrasonic elliptical vibration at a driving point by two vibration modes of vertical and bending, and a basic technique necessary for driving the ultrasonic actuator. Is disclosed.

  In the technique based on this proposal, when driving the ultrasonic actuator (described as the ultrasonic linear motor in the specification of the publication), the A phase and the B phase as shown in FIG. 9A or 9B are used. By applying drive signals having a phase difference of 90 ° to the ultrasonic transducer 57A (see FIG. 10) constituting the ultrasonic actuator, longitudinal vibration as shown in FIG. 10 (a) and FIG. 10 (b). Two vibration modes with bending vibration as shown are excited simultaneously. 9A to 9D, the drive signal is shown as a rectangular wave signal, but it may be a sine wave.

  As a result, elliptical vibration as shown in FIG. 10C is generated in the frictional contact portion 57C (see FIG. 10) provided in the ultrasonic transducer 57A, and the driven portion 57B is driven by this elliptical vibration. Will do. In this case, by setting the phase of the B phase to + 90 ° or −90 °, the rotational direction of the elliptical vibration is opposite, that is, the drive direction can be controlled. FIG. 9 (c) shows a drive signal in which the phases of the A phase and the B phase are the same during longitudinal vibration, and FIG. 9 (d) shows the phases of the A phase and the B phase are reversed during bending vibration. The drive signal which is is shown.

Although not shown, a conventional drive circuit that realizes such drive control of an ultrasonic actuator includes, for example, a control unit that controls the drive of an ultrasonic actuator composed of an ultrasonic transducer and a driven body, and a drive signal. A first oscillating unit that generates a source signal and determines the frequency of the drive signal by the control of the control unit; and a phase of + 90 ° or −90 ° at the same frequency as the first oscillating unit by the control of the control unit. A second oscillating section that oscillates in a controllable manner, and a driving section that includes two first and second driving circuits that amplify the output signals of the two first and second oscillating sections and apply them to the ultrasonic actuator. In this way, drive control of the ultrasonic actuator is performed.
JP 7-163162 A

  In the conventional ultrasonic actuator driving circuit, the control and start control of the ultrasonic vibrator is simply applied to the ultrasonic vibrator by a two-phase (A phase, B phase) driving signal by the control unit. Or, it is done so as to cut off. However, in such a control method, the change in the driving force of the ultrasonic actuator 57 is steep with respect to the driven body 57B having an inertial mass, so that the stop position becomes inaccurate particularly in the stop operation. There is a disadvantage that the load on the driving mechanism of the ultrasonic actuator 57 and the driven portion 57B becomes large.

FIG. 11A shows an example of control by the conventional ultrasonic actuator driving circuit, and FIG. 11B shows the operating state of the driven body driven based on the control. It is shown.
As shown in FIGS. 11A and 11B, at first, the ultrasonic actuator 57 and the driven body 57B are in a stopped state from time t0 to time t1. Then, at time t1 at the time of starting (at the start of driving), the control unit outputs a control signal to the first oscillation unit and the second oscillation unit, and B phase having a phase difference of + 90 ° or −90 ° with the A phase signal. The phase signal is applied to the ultrasonic transducer 57A via the power amplifier. Thereby, elliptical vibration is generated in the ultrasonic transducer 57A. Then, the driven body 57B in the ultrasonic actuator 57 gradually increases in speed and becomes a constant speed as shown in FIG.
Then, when the driven body 57B reaches a predetermined position (for example, a predetermined position Ly before the target position Lo shown in FIG. 11B), the control unit controls to stop power supply at time tx. However, after that, the driven body 57B moves a distance (assumed inertial movement distance Lz) according to the speed, inertial mass, and friction before power supply interruption due to inertia. In other words, in the conventional control method, the power supply is controlled to stop before the target position Lo in anticipation of this, but the ultrasonic actuator 57 is suddenly turned off, so that it is driven from the load. Thus, a load is applied to the mechanical members of the drive system. That is, the ultrasonic actuator 57 drives the driven body 57B with elliptical vibration generated in the ultrasonic driver 57A, but when the feeding is stopped at time tx, the driven body 57B causes the ultrasonic transducer 57A to move. Dragging, and a large frictional force is generated. Usually, since the ultrasonic driver 57A employs a structure that adheres to the ultrasonic actuator 57, the burden on the bonded portion is large. At the same time, wear of the contact portion (friction contact portion 57C) between the ultrasonic driver 57A and the driven body 57B also proceeds.

As described above, the distance moved by inertia (the inertial movement assumed distance Lx) varies depending on the variation in frictional force. The ultrasonic actuator 57 often changes its speed depending on the moving distance of the driven body 57B, and as a result, the variation in the moving distance due to inertia increases. Therefore, it is difficult to realize an accurate stop position of the driven body 57B.
In the prior art, with respect to the stop position, usually, a separate position detection means such as a linear scale is provided, and a method of pulling to the target position by fine feed / return is adopted. However, in such a conventional technique, if the stop accuracy of the ultrasonic actuator alone is poor, a lot of feed / return control occurs when it converges to the target position, resulting in an increase in time for the stop control. There were also inconveniences.

  Accordingly, the present invention has been made in view of the above problems, and it is possible to perform accurate drive control that can reduce the burden on the drive mechanism in the ultrasonic actuator and obtain an accurate stop position with a simple configuration. An object is to provide an ultrasonic actuator driving apparatus and an actuator driving method.

  An ultrasonic actuator driving apparatus according to a first aspect of the present invention includes an ultrasonic transducer in which piezoelectric layers and internal electrode layers are alternately stacked, and an object to be moved relatively in contact with at least a part of the ultrasonic transducer. An ultrasonic actuator provided with a driving body; an oscillating unit that generates an AC signal; a phase shift unit that generates a two-phase driving signal based on the AC signal; and amplifying the two-phase driving signal; An ultrasonic wave having a drive unit that generates longitudinal vibration and / or flexural vibration in the ultrasonic transducer by applying the ultrasonic transducer, and a control unit that controls the oscillation unit, the phase shift unit, and the drive unit. In the actuator driving device, the control unit gradually changes a driving force for the driven body by switching a vibration state of the ultrasonic transducer when starting or stopping the driven body. Is shall.

  An ultrasonic actuator driving apparatus according to a second aspect of the present invention is the ultrasonic actuator driving apparatus according to the first aspect, wherein the control unit applies only flexural vibration to the ultrasonic vibrator when activating the driven body. After the generation, the phase difference between the two-phase drive signals is controlled so as to generate the longitudinal vibration and the bending vibration.

  An ultrasonic actuator driving apparatus according to a third aspect of the present invention is the ultrasonic actuator driving apparatus according to the first aspect, wherein the control unit decelerates and stops the driven body that is being driven. The driving force applied to the driven body is gradually changed by using a combination of a period during which the application of the driving signal is stopped and a period during which bending vibration is generated.

  According to a fourth aspect of the present invention, there is provided the ultrasonic actuator driving apparatus according to the first aspect, wherein the control unit decelerates and stops the driven body that is being driven. Then, after only bending vibration is generated for a predetermined period, application of the drive signal is stopped.

  An ultrasonic actuator driving apparatus according to a fifth aspect of the present invention is the ultrasonic actuator driving apparatus according to the first aspect, wherein the control unit decelerates and stops the driven body that is being driven. Bending vibration is generated after the application of the drive signal to is stopped for a predetermined period.

  An ultrasonic actuator driving apparatus according to a sixth aspect of the present invention is the ultrasonic actuator driving apparatus according to any one of the third to fifth aspects, wherein the control section generates a bending vibration in the ultrasonic transducer. In doing so, the amplitude of the drive signal applied to the ultrasonic transducer is gradually changed.

  An ultrasonic actuator driving apparatus according to a seventh aspect of the invention is the ultrasonic actuator driving apparatus according to any one of the third to fifth aspects, wherein the control unit generates a bending vibration in the ultrasonic transducer. In doing so, the frequency of the drive signal applied to the ultrasonic transducer is gradually changed.

  According to an eighth aspect of the present invention, there is provided an ultrasonic actuator driving method comprising: an ultrasonic transducer comprising alternately laminated piezoelectric layers and internal electrode layers; and an object to be moved relatively in contact with at least a part of the ultrasonic transducer. An ultrasonic actuator having a drive body is provided, and longitudinal vibration and / or bending is applied to the ultrasonic vibrator by applying a two-phase drive signal generated based on an AC signal to the ultrasonic vibrator. An ultrasonic actuator driving method for driving by generating vibrations, wherein when the driven body is started or stopped, the driving force to the driven body is gradually increased by switching the vibration state of the ultrasonic vibrator. It is characterized by being changed to.

  The ultrasonic actuator driving method according to the ninth aspect of the invention is the ultrasonic actuator driving method according to the eighth aspect of the invention, wherein when the driven body is activated, only the bending vibration is generated in the ultrasonic vibrator, The phase difference between the two-phase driving signals is controlled so as to generate vibration and bending vibration.

  An ultrasonic actuator driving method according to a tenth aspect of the present invention is the ultrasonic actuator driving method according to the eighth aspect, wherein the drive signal to the ultrasonic transducer is used to decelerate and stop the driven body being driven. The driving force with respect to the driven body is gradually changed by combining a plurality of periods in which the application of power is stopped and a period in which bending vibration is generated.

  The ultrasonic actuator driving method according to an eleventh aspect of the invention is the ultrasonic actuator driving method according to the eighth aspect, wherein only the bending vibration is applied to the ultrasonic vibrator when the driven body being driven is decelerated and stopped. After the generation for a predetermined period, the application of the drive signal is stopped.

  An ultrasonic actuator driving method according to a twelfth aspect of the present invention is the ultrasonic actuator driving method according to the eighth aspect, wherein the drive signal to the ultrasonic transducer is used to decelerate and stop the driven body being driven. After the application of is stopped for a predetermined period, bending vibration is generated.

  An ultrasonic actuator driving method according to a thirteenth aspect of the invention is the ultrasonic actuator driving method according to any one of the tenth to twelfth aspects, wherein the ultrasonic wave is generated when the bending vibration is generated in the ultrasonic transducer. The drive signal applied to the vibrator is gradually changed in amplitude.

  An ultrasonic actuator driving method according to a fourteenth aspect of the present invention is the ultrasonic actuator driving method according to any one of the tenth to twelfth aspects, wherein the ultrasonic wave is generated when the bending vibration is generated in the ultrasonic transducer. The frequency of the drive signal applied to the vibrator is gradually changed.

  The ultrasonic actuator driving apparatus and the ultrasonic actuator driving method of the present invention can reduce the burden on the driving mechanism in the ultrasonic actuator with a simple configuration and can perform accurate driving control that can obtain an accurate stop position. There is an advantage that there is.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 to 5 show a first embodiment of an ultrasonic actuator driving apparatus according to the present invention, and FIG. 1 is a block diagram showing the overall configuration of the ultrasonic actuator driving apparatus, FIGS. 2 (a) and 2 (b). FIG. 2 shows a configuration example of the ultrasonic actuator of FIG. 1, FIG. 2 (a) is a front view, and FIG. 2 (b) is a side view. 3 is an exploded perspective view of the piezoelectric laminated body of FIG. 2 laminated in the Y-axis direction, and FIG. 4 is a block diagram showing a specific configuration example of the current detection unit and the phase detection unit of FIG. 5 is a graph showing the operating state of the ultrasonic actuator based on the control operation using the ultrasonic actuator driving method of the present embodiment.

  As shown in FIG. 1, the ultrasonic actuator driving apparatus 1 of the present embodiment is a second vibration information detecting device that drives the ultrasonic actuator 5 having an ultrasonic transducer 5 </ b> A and a driven portion 5 </ b> B, which will be described later. The control unit 2 that controls based on the detection result from the unit 6, and the oscillation unit 7 that generates a source signal of the drive signal that drives the ultrasonic actuator 5 and determines the frequency of the drive signal under the control of the control unit 2. A drive unit 3 for applying an output signal from the oscillation unit 7 to the ultrasonic actuator 5 through a power amplification unit 9, and an output signal (drive signal) of the drive unit 3 is taken in. An ultrasonic actuator that drives using a frictional force generated between the first vibration information detection unit 4 that detects the current of the drive signal flowing through 5 and the driven unit 5B that contacts the ultrasonic transducer 5A. The eta 5, the output signal (drive signal) of the drive unit 3 and the detection result of the first vibration information detection unit 4 are fetched, and the output signal (drive signal) of the drive unit 3 and the first vibration information detection unit 4 are input. And a second vibration information detection unit 6 that detects a phase difference from the detected current and outputs a detection result to the control unit 2.

  Although the detailed configuration of the ultrasonic actuator driving device 1 will be described later, the configuration of the ultrasonic actuator 5 provided in the ultrasonic actuator driving device 1 will be described with reference to FIGS. 2 (a) and 2 (b). While explaining.

  As shown in FIGS. 2 (a) and 2 (b), the ultrasonic actuator 5 includes an ultrasonic transducer 5A composed of a prismatic piezoelectric laminate, and a piezoelectric laminate of the ultrasonic transducer 5A. A driven part 5B disposed so as to be in contact with each other via a friction member 20 described later, external electrodes 19 provided on two left and right side surfaces of the piezoelectric laminate of the ultrasonic transducer 5A, and For example, the piezoelectric laminate of the ultrasonic transducer 5A has a friction member 20 bonded to two locations, for example, an upper surface and a bottom surface.

  As shown in FIG. 3, the piezoelectric laminated body of the ultrasonic transducer 5A has a thin rectangular piezoelectric plate 5a that has been subjected to an internal electrode treatment, placed in a Y-axis direction (a direction orthogonal to the vibration direction of the ultrasonic transducer 5A). It is laminated and integrated in the depth direction of the acoustic wave vibrator 5A. Each piezoelectric plate 5a has an internal electrode 5b having a predetermined shape by being subjected to internal electrode processing.

  The external electrode 19 on the right side in the figure is attached to an internal electrode exposed part (not shown) taken out from the right side part in the figure of the piezoelectric laminate of the ultrasonic transducer 5A, whereby two electrical terminals (A +, Both terminals A-) are configured as A (A phase). Further, the external electrode 19 on the left side in the figure is attached to an internal electrode exposed part (not shown) taken out from the left side surface part in the figure of the piezoelectric laminate, thereby providing two electrical terminals (B +, B−). Both terminals) are configured as B (B phase). In this case, the A- and B- terminals are on the negative side of the A phase and B phase, respectively, in the case of a balanced circuit. You may comprise so that it may become an electric potential.

Although not shown, lead wires are connected to these external electrodes 19 with solder or the like, and these lead wires are connected to the first vibration information detection unit 4.
The friction member 20 is provided at a position of an antinode of bending vibration generated on the top and bottom surfaces of the piezoelectric laminate in contact with the driven portion 5B.
In this configuration example, the ultrasonic transducer 5A is configured such that the longitudinal dimension is, for example, 5 to 20 mm. Further, the pressing force applied when the ultrasonic actuator 5 including the ultrasonic transducer 5A and the driven portion 5B is configured is, for example, 0.1 to 5 kg.

Next, a detailed configuration of the ultrasonic actuator driving apparatus 1 that drives the ultrasonic actuator 5 will be described with reference to FIGS. 1 and 4.
As shown in FIG. 1, the control unit 2 generates control signals 2 a and 2 b, outputs the control signal 2 a to the oscillation unit 7 of the drive unit 3, and outputs the control signal 2 b to the phase shift unit of the drive unit 3. 8 is output.
The driving unit 3 determines the predetermined frequency of the driving signal by the control signal 2a and outputs the A phase signal 8a, and + 90 °, −90 °, 180 ° with respect to the A phase signal 8a of the oscillating unit 7. The phase shift unit 8 that converts and outputs the phase B signal 8b having a phase difference of 0 °, the phase A signal 8a and the phase B signal 8b are taken in, the power of these two signals is amplified, and the first, And a power amplifying unit 9 that outputs the second vibration information detecting units 4 and 6.

The oscillation unit 7 outputs an A-phase signal 8 a having a frequency corresponding to the control signal 2 a to the phase shift unit 8 and the power amplification unit 9.
The phase shifter 8 converts the supplied A-phase signal 8a into a B-phase signal having phase differences of + 90 °, −90 °, and 180 °, and outputs the B-phase signal to the power amplifier 9. In this case, the phase shifter 8 receives the A phase signal (= 0 ° phase signal), + 90 ° phase signal, −90 ° phase signal, 180 ° based on the control signal 2b from the control unit 2. Any one of the phase signals is selectively output to the power amplifier 9 as the B phase signal.

  The power amplifier 9 amplifies the power of the two input A-phase signals 8a and B-phase signals 8b, converts them into bipolar signals, and outputs them (balanced output). That is, the two A-phase signals 8a and B-phase signals 8b that are output signals of the power amplifier 9 are supplied to the ultrasonic transducer 5A of the ultrasonic actuator 5 via the first vibration information detector 4. . Further, the output signal of the power amplifier 9 is also supplied to the second vibration information detector 6.

The first vibration information detection unit 4 includes an A-phase current detection unit 10 that detects an A-phase current, and a B-phase current detection unit 11 that detects a B-phase current, and each flows through the ultrasonic transducer 5A. This is for detecting the current value.
Specifically, the A-phase current detection unit 10 and the B-phase current detection unit 11 are, as shown in FIG. 4, a resistor 14 and a differential amplifier circuit 15 that detects a difference between both end voltages of the resistor 14. And it consists of. The resistance value of the resistor 14 is sufficiently smaller than the DC resistance value of the ultrasonic transducer 5A and is detected by the second vibration information detection unit 6 together with the gain of the differential amplifier circuit 15. It is sufficient to select a value that does not cause an error, and usually a value of several Ω or less is taken.

In normal operation, when an A-phase drive signal and a B-phase drive signal having a phase difference of + 90 ° or −90 ° are output to the ultrasonic transducer 5A, the ultrasonic transducer 5A is provided in itself. Elliptical vibration is generated in the friction member 20 (see FIGS. 2A and 2B) to drive the driven portion 5B. In this case, the direction of elliptical vibration, that is, the direction in which the driven part 5B is driven is determined by whether the phase of the B phase with respect to the A phase is + 90 ° or −90 °.
Further, when the phase difference between the A phase and the B phase is 0 °, the ultrasonic transducer 5A generates only the longitudinal vibration shown in FIG. Further, when the phase difference between the A phase and the B phase is 180 °, only the bending vibration shown in FIG. 10B is generated in the ultrasonic transducer 5A.

  The second vibration information detection unit 6 includes an A-phase phase difference detection unit 12 that detects a phase difference between an A-phase voltage and a current, and a B-phase phase difference detection unit 13 that detects a phase difference between a B-phase voltage and a current. is doing. The A-phase phase difference detection unit 12 and the B-phase phase difference detection unit 13 include the first information detection unit 4 (A-phase and B-phase current detection) that detects an output voltage and a drive current waveform of the power amplification unit 9. The output signals of the units 10 and 11) are inputted.

  The A-phase phase difference detection unit 12 and the B-phase phase difference detection unit 13 detect a phase difference between the A-phase or B-phase voltage and current. For example, a phase comparator of a PLL (Phase Locked Loop) IC 4046 is used. Is configured. The phase differences between the voltages and currents of the A phase and B phase detected by the A phase phase difference detection unit 12 and the B phase phase difference detection unit 13 are input to the control unit 2.

The control unit 2 controls the control signal 2a to the oscillation unit 7 of the drive unit 3 and the control signal 2b to the phase shift unit 8 based on the detection result (phase information) from the second vibration information detection unit 6. Then, drive control of the ultrasonic actuator 5 is performed.
Next, an ultrasonic actuator driving method applied to the ultrasonic actuator driving apparatus having the above-described configuration will be described with reference to FIGS.
In this embodiment, when the ultrasonic actuator driving method is performed, it is necessary to determine the driving frequency of the ultrasonic transducer 5A in advance. Therefore, description will be made assuming that the drive frequency is set in advance.
The ultrasonic actuator 5 has three vibration modes of longitudinal vibration, bending vibration, and elliptical vibration obtained by generating longitudinal vibration and bending vibration at the same time as described above, and the frequencies may be slightly different. Moreover, each frequency changes with temperature changes. Here, for simplification of explanation, each vibration of longitudinal vibration, bending vibration, and elliptical vibration is assumed to be generated at the same known frequency. Furthermore, FIG. 5 shows the longitudinal vibration mode as “vertical”, the bending vibration mode as “bending”, and the elliptical vibration mode as “bending + longitudinal” among the three vibration modes.

  As shown in FIG. 5, at time t0 to t1, first, since the drive control by the control unit 2 is not performed (hereinafter referred to as a non-feed mode), the ultrasonic actuator 5 and the target The driver 5B is in a stopped state.

  Then, at time t1 at the time of starting (at the start of driving), the control unit 2 outputs a control signal 2a so that the oscillation unit 7 oscillates at a predetermined frequency. At the same time, the control unit 2 controls the phase shift unit 8 to output a control signal 2b so that the phase shift unit 8 outputs a B phase signal 8b having a phase difference of 180 ° from the A phase signal 8a. The two-phase signals of the A-phase signal 8a and the B-phase signal 8b are applied to the ultrasonic transducer 5A via the power amplification unit 9 that performs power amplification and the current detection units 10 and 11 of the A and B phases. Is done. As a result, only the bending vibration (see FIG. 10B) is generated in the ultrasonic transducer 5A in the region A between time t1 and time t2.

  Next, in order to generate elliptical vibration in the ultrasonic transducer 5A, the control unit 2 outputs a control signal 2b to the phase shift unit 8 at time t2, and the phase shift unit based on this control signal. 8 outputs an A-phase signal 8a and a + 90 ° or -90 ° B-phase signal 8b.

At this time, when the A-phase signal 8a and the B-phase signal 8b have a phase difference of 90 °, the ultrasonic transducer 5A generates elliptical vibrations in the vicinity of the frictional contact portion 20 as shown in FIG. Then, the driven body 5B is driven. The driving direction of the driven body 5B is opposite in the + 90 ° and −90 ° of the B-phase signal 8b.
In this way, the driven portion 5B starts to move in the region B between time t2 and time t3, and gradually increases in speed to a constant speed as shown in FIG.

  In this embodiment, since the longitudinal vibration is generated from the state in which the bending vibration has already occurred, unnecessary friction between the friction contact portion 20 of the ultrasonic transducer 5A and the driven body 5B can be avoided. . Usually, the friction contact portion 20 is bonded and fixed to the ultrasonic transducer 5A. However, unnecessary stress on the friction contact portion 20 can be reduced, that is, the friction coefficient can be reduced. Further, in this embodiment, the wear of the contact surface between the friction contact portion 20 and the driven body 5B can be reduced.

  Then, after the driven body 5B reaches the predetermined speed at time t3, the control unit 2 sets the driven body 5B to a predetermined distance before the stop position in the B1 region between time t3 and time t4. Detecting that it has arrived. This is detected by a scale provided separately. If the scale is not used, it is only necessary to detect that it is arranged at a predetermined distance before a certain time by managing the drive itself by time by the control unit 2.

  Next, at time t4, stop control of the driven body 5B is performed. Then, the control unit 2 changes the control signal 2b to the phase shift unit 8 within the C region between time t4 and time t5, and the phase shift unit 8 and the phase A signal 8a are 180 degrees out of phase. Control is performed so that the B-phase signal 8b is output. The two-phase signals of the A-phase signal 8a and the B-phase signal 8b are applied to the ultrasonic transducer 5A via the power amplification unit 9 that performs power amplification and the current detection units 10 and 11 of the A and B phases. Is done.

  Then, only the bending vibration (see FIG. 10B) is generated in the ultrasonic transducer 5A. At this time, the frictional contact portion 20 of the ultrasonic actuator 5 periodically presses the driven body 5B, but this does not have a driving force and only a certain pressure is applied to the driven body 5B. Will occur. As a result, a braking effect is produced on the driven body 5B. On the other hand, when the power supply to the ultrasonic actuator 5 is completely stopped, the frictional contact portion 20 is always brought into close contact with and dragged to the driven body 5B and becomes a strong brake. When the vibration mode is executed, a gentle deceleration effect can be obtained. Thereby, in this embodiment, since the frictional contact portion 20 is not dragged as described above, adverse effects such as a load on the drive mechanism portion can be reduced.

  Thereafter, when the driven body 5B further travels a certain distance in the deceleration state due to the bending vibration, the control unit 2 performs control so as to stop the power supply to the ultrasonic actuator 5 in the region D after time t5. As a result, strong braking is applied to the driven body 5B, and the driven body 5B stops at time tz. At this point in time, the speed of the driven body 5B has dropped sufficiently, so that the adverse effect on the drive mechanism portion is small. Then, the scale is checked at the place where it stopped, and if there is an excess or deficiency with respect to the target point, it may be corrected by fine feed.

  As described above, according to the present embodiment, the start and stop of the driven body 5B are controlled so as to perform stepwise acceleration / deceleration, thereby reducing the adverse effects on the drive mechanism and accurately. Therefore, it is possible to drive the ultrasonic actuator 5 with high accuracy.

  In the present embodiment, in the control operation example by the control unit 2, the case where the bending vibration mode, the elliptical vibration mode, and the non-feeding mode are appropriately executed within the period A to D has been described. The driving force for the driven body 5B is gradually changed by controlling the period corresponding to the bending vibration mode, the longitudinal vibration mode, the elliptical vibration mode, and the non-feeding mode in combination. May be stopped.

FIG. 6 is a graph showing an operation state of the ultrasonic actuator based on the control operation using the ultrasonic actuator driving method according to the second embodiment of the ultrasonic actuator driving device of the present invention.
The configuration of the ultrasonic actuator driving apparatus of this embodiment is the same as that of the first embodiment. Further, the ultrasonic actuator driving apparatus of the present embodiment applies the ultrasonic actuator driving method of the first embodiment. However, when performing the deceleration stop operation, the non-feed mode for sudden deceleration and the bending vibration mode for slow deceleration are performed. Is controlled so that effective deceleration can be achieved.

Such an ultrasonic actuator driving method of this embodiment will be described with reference to FIG.
Now, it is assumed that the ultrasonic actuator 5 is driven by executing the elliptical vibration mode in the region A between time t0 and time t1. In this case, the operation from the activation of the ultrasonic actuator 5 to the execution of the elliptical vibration mode is substantially the same as in the first embodiment.

  That is, at the start (when driving is started), the control unit 2 outputs the control signal 2a so that the oscillation unit 7 oscillates at a predetermined frequency. At the same time, the control unit 2 controls the phase shift unit 8 to output a control signal 2b so that the phase shift unit 8 outputs a B phase signal 8b having a phase difference of 180 ° from the A phase signal 8a. The two-phase signals of the A-phase signal 8a and the B-phase signal 8b are applied to the ultrasonic transducer 5A via the power amplification unit 9 that performs power amplification and the current detection units 10 and 11 of the A and B phases. Is done. As a result, only the bending vibration (see FIG. 10B) is generated in the ultrasonic transducer 5A.

  Next, in order to cause the ultrasonic transducer 5A to generate elliptical vibration, the control unit 2 outputs a control signal 2b to the phase shift unit 8, and based on this control signal, the phase shift unit 8 The phase signal 8a and the B phase signal 8b of + 90 ° or −90 ° are output.

At this time, when the A-phase signal 8a and the B-phase signal 8b have a phase difference of 90 °, the ultrasonic transducer 5A generates elliptical vibrations in the vicinity of the frictional contact portion 20 as shown in FIG. Then, the driven body 5B is driven. The driving direction of the driven body 5B is opposite in the + 90 ° and −90 ° of the B-phase signal 8b.
In this way, the driven portion 5B starts to move and gradually increases the speed to a constant speed as in the first embodiment.

  Then, after the driven body 5B reaches a predetermined speed, the control unit 2 confirms that the driven body 5B has reached a predetermined distance before the stop position in the area A between time t0 and time t1. To detect. This is detected by a scale provided separately. If the scale is not used, it is only necessary to detect that it is arranged at a predetermined distance before a certain time by managing the drive itself by time by the control unit 2.

  Next, at time t1, stop control of the driven body 5B is performed. In this case, in this embodiment, the control unit 2 changes the control signal 2b to the phase shift unit 8 in the B region between the time t1 and the time t2 to change between the A phase signal 8a and the B phase signal 8b. Control is performed so that the phase difference is 180 °. As a result, bending vibration is generated in the ultrasonic transducer 5A, and gentle braking is applied to the driven body 5B. After a predetermined time (time up to time t2) has elapsed in this state, the control unit 2 executes the non-feed mode in the C region between time t2 and time t3, that is, a control signal to the oscillation unit 7 2a is changed to control to stop the oscillation. Thereby, strong braking is applied to the driven body 5B.

  Thereafter, in the present embodiment, the control unit 2 performs control so as to repeat this bending vibration state (bending vibration mode) and oscillation stop state (non-feeding mode). That is, the control unit 2 performs control so as to execute the bending vibration mode in the D region between time t3 and time t4 in the same manner as described above, and thereafter in the E region between time t4 and time t5 in the same manner as described above. By controlling to execute the non-feed mode, the driven body 5B is decelerated and stopped in the F region between time t5 and time tz. At this time, as in the first embodiment, the scale is confirmed at the place where it has stopped, and if there is an excess or deficiency with respect to the target point, it may be corrected by fine feed.

  Therefore, according to the present embodiment, in addition to obtaining the same effect as the first embodiment, in order to stop the ultrasonic actuator 5 being driven, control is performed so as to combine a plurality of bending vibration modes and non-feed modes. Thus, it is possible to reduce the burden on the drive mechanism and obtain a more accurate stop position.

  FIG. 7 is a graph showing an operation state of an ultrasonic actuator based on a control operation using the ultrasonic actuator driving method according to a third embodiment of the ultrasonic actuator driving apparatus of the present invention. FIG. 8 is a graph showing the third embodiment. 8A is a graph showing a control example when the amplitude of the drive signal is gradually changed during execution of the bending vibration mode, and FIG. 8B is a drive signal when the bending vibration mode is executed. FIG. 8C is a graph showing a control example when the frequency of the drive signal is gradually changed during execution of the bending vibration mode. is there.

In the ultrasonic actuator driving method of the first embodiment, the driven part such as the driven body 5B having a large inertial mass is accurately stopped without imposing a load on the mechanism part, but the inertial mass of the drive part is small. In other cases, the time to stop may be minimized rather than the influence on the mechanism. In such a case, a control method is also effective in which power supply is stopped first and strong braking is applied, and then gradually stopped by bending vibration.
An embodiment employing such a control method will be described with reference to FIG. The configuration of the ultrasonic actuator driving apparatus of this embodiment is the same as that of the first embodiment.

  As shown in FIG. 7, it is assumed that the ultrasonic actuator 5 is driven by executing the elliptical vibration mode in the region A between time t0 and time t1. In this case, the operation from the activation of the ultrasonic actuator 5 to the execution of the elliptical vibration mode is substantially the same as in the first embodiment.

  That is, at the start (when driving is started), the control unit 2 outputs the control signal 2a so that the oscillation unit 7 oscillates at a predetermined frequency. At the same time, the control unit 2 controls the phase shift unit 8 to output a control signal 2b so that the phase shift unit 8 outputs a B phase signal 8b having a phase difference of 180 ° from the A phase signal 8a. The two-phase signals of the A-phase signal 8a and the B-phase signal 8b are applied to the ultrasonic transducer 5A via the power amplification unit 9 that performs power amplification and the current detection units 10 and 11 of the A and B phases. Is done. As a result, only the bending vibration (see FIG. 10B) is generated in the ultrasonic transducer 5A.

  Next, in order to cause the ultrasonic transducer 5A to generate elliptical vibration, the control unit 2 outputs a control signal 2b to the phase shift unit 8, and based on this control signal, the phase shift unit 8 The phase signal 8a and the B phase signal 8b of + 90 ° or −90 ° are output.

At this time, when the A-phase signal 8a and the B-phase signal 8b have a phase difference of 90 °, the ultrasonic transducer 5A generates elliptical vibrations in the vicinity of the frictional contact portion 20 as shown in FIG. Then, the driven body 5B is driven. The driving direction of the driven body 5B is opposite in the + 90 ° and −90 ° of the B-phase signal 8b.
In this way, the driven portion 5B starts to move and gradually increases the speed to a constant speed as in the first embodiment.

  Also in the present embodiment, since the longitudinal vibration is generated from the state in which the bending vibration has already occurred as in the first embodiment, the friction contact portion 20 of the ultrasonic transducer 5A and the driven body 5B are Unnecessary friction can be avoided. Usually, the friction contact portion 20 is bonded and fixed to the ultrasonic transducer 5A. However, unnecessary stress on the friction contact portion 20 can be reduced, that is, the friction coefficient can be reduced. Also in this embodiment, the wear of the contact surface between the friction contact portion 20 and the driven body 5B can be reduced.

  Then, after the driven body 5B reaches a predetermined speed, the controller 2 determines that the driven body 5B is disposed at a predetermined distance before the stop position in the area A between time t0 and time t1. Is detected. This is detected by a scale provided separately. If the scale is not used, it is only necessary to detect that it is arranged at a predetermined distance before a certain time by managing the drive itself by time by the control unit 2.

  Next, at time t1, stop control of the driven body 5B is performed. Then, the control unit 2 commands the oscillation unit 7 to stop oscillation in the region B between time t1 and time t2, and stops power supply to the ultrasonic actuator 5. That is, the control unit 2 causes the non-feed mode to be executed. Thereby, strong braking is applied to the driven body 5B, and the driven body 5B moves with inertia while rapidly decelerating.

  Subsequently, when it is detected that the driven body 5B has reached a predetermined position as described above, the control unit 2 detects the oscillation unit 7 and the phase shift in the C region between the time t2 and the time tz. The control signals 2a and 2b to the unit 8 are changed so that the B-phase signal 8b becomes a B-phase signal 8b that is 180 ° out of phase with the A-phase signal 8a. These two-phase signals (A-phase signal 8a and B-phase signal 8b) are amplified in power and applied to the ultrasonic actuator 5.

  Then, bending vibration is generated in the ultrasonic transducer 5A, and the driven body 5B is gently braked, and stops at time tz. At this time, as in the first embodiment, the scale is confirmed at the place where it has stopped, and if there is an excess or deficiency with respect to the target point, it may be corrected by fine feed.

Therefore, according to the present embodiment, as described above, by controlling the acceleration and deceleration of the driven body 5B in stages, adverse effects on the drive unit mechanism can be reduced, and the drive unit can be stopped accurately in a short drive time. It becomes possible.
In the present embodiment, the braking by the execution of the bending vibration mode is uniform. However, for example, by increasing or decreasing the driving power (driving voltage) applied to the ultrasonic actuator 5, from weak braking to strong braking. Control that changes is also possible. Such a modification is schematically shown in FIG.
As shown in FIG. 8 (a), the bending vibration is attenuated by gradually lowering the A and B phase drive voltages in the period between time t1 and time tx by the control of the control unit 2. The braking force will increase. That is, when the precursor driving voltage is lowered, the friction coefficient between the frictional contact portion 20 of the ultrasonic transducer 5A and the driven body 5B is increased due to the attenuation of the bending vibration, so that the braking force is also increased accordingly. The speed will also decay and stop.

In this embodiment, it is also possible to control the braking by changing the average pressure of the bending vibration by changing the drive frequency of the ultrasonic actuator 5. Such a modification is schematically shown in FIGS. 8B and 8C.
As shown in FIGS. 8A and 8B, by the control by the control unit 2, the driving is first started at the resonance frequency f1 of the flexural vibration at time t1, and thereafter between time t1 and time tx. In the predetermined period, the frequency is gradually increased to reach the frequency f2. That is, when the driving frequency is separated from the resonance frequency f1, the flexural vibration is attenuated and the friction coefficient between the friction contact portion 20 and the driven body 5B is increased, so that the braking force is increased accordingly. In such a modified example, a similar effect can be obtained even if the frequency is lowered instead of the above.

  It should be noted that the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention.

1 to 6 show a first embodiment of an ultrasonic actuator driving apparatus according to the present invention, and FIG. 1 is a block diagram showing an overall configuration of the ultrasonic actuator driving apparatus. FIG. 2 is a configuration diagram showing a configuration example of the ultrasonic actuator of FIG. FIG. 3 is an exploded perspective view of the piezoelectric laminate in FIG. 2 that is laminated in the Y-axis direction. The block diagram which shows the specific structural example of the electric current detection part of FIG. 1, and a phase detection part. FIG. 5 is a graph showing an operation state of the ultrasonic actuator based on the control operation using the ultrasonic actuator driving method of the present embodiment. The graph which shows 2nd Example of the ultrasonic actuator drive device of this invention, and shows the operation state of the ultrasonic actuator based on control operation using the ultrasonic actuator drive method. The graph which shows 3rd Example of the ultrasonic actuator drive device of this invention, and shows the operation state of the ultrasonic actuator based on control operation using the ultrasonic actuator drive method. The graph for demonstrating the modification of 3rd Example and demonstrating the example of control during bending vibration mode execution. The wave form diagram which shows the waveform of the drive signal applied to an ultrasonic transducer | vibrator. Explanatory drawing for demonstrating the longitudinal vibration, bending vibration, and elliptical vibration of an ultrasonic transducer | vibrator. The graph which shows the example of control by the conventional ultrasonic actuator drive device, and the operation state of a to-be-driven body.

Explanation of symbols

1 ... ultrasonic actuator driving device,
2 Control unit,
2A ... characteristic data section,
2B ... Required specification part,
2C: arithmetic unit,
2a, 2b ... control signals,
3 ... Drive unit,
4 ... 1st vibration information detection part,
5 ... Ultrasonic actuator,
5A ... ultrasonic transducer,
5B: driven part,
5a ... piezoelectric plate,
5b ... internal electrode,
6 ... 2nd vibration information detection part,
7: Oscillator,
8 ... Phase shift part,
9: Power amplifier,
10 ... A phase current detector 11 ... B phase current detector,
12 ... A phase phase difference detector,
13 ... B phase phase difference detection unit,
15 ... differential amplifier circuit,
16 ... band pass filter,
17: Comparison circuit,
18 ... Phase comparator,
20: Friction member.
Agent Patent Attorney Susumu Ito

Claims (14)

An ultrasonic actuator comprising an ultrasonic vibrator formed by alternately laminating piezoelectric layers and internal electrode layers, a driven body that moves relative to at least a part of the ultrasonic vibrator, and an AC signal. An oscillating unit for generating, a phase shifting unit for generating a two-phase drive signal based on the AC signal, and amplifying the two-phase drive signal and applying the amplified signal to the ultrasonic transducer, thereby generating the ultrasonic vibration. In an ultrasonic actuator driving apparatus comprising: a drive unit that generates longitudinal vibration and / or bending vibration in a child; and a control unit that controls the oscillation unit, the phase shift unit, and the drive unit.
The control unit gradually changes a driving force for the driven body by switching a vibration state of the ultrasonic vibrator when starting or stopping the driven body. apparatus.   The control unit controls the phase difference between the two-phase drive signals so as to generate longitudinal vibration and bending vibration after generating only bending vibration in the ultrasonic vibrator when starting the driven body. The ultrasonic actuator driving apparatus according to claim 1.   The controller, when decelerating and stopping the driven body that is being driven, by using a combination of a period for stopping application of the drive signal to the ultrasonic transducer and a period for generating bending vibration, The ultrasonic actuator driving apparatus according to claim 1, wherein a driving force for the driven body is gradually changed.   The control unit, when decelerating and stopping the driven body being driven, causes the ultrasonic transducer to generate only bending vibration for a predetermined period, and then stops applying the drive signal. Item 2. The ultrasonic actuator driving device according to Item 1.   The control unit, when decelerating and stopping the driven body that is being driven, generates bending vibration after stopping the application of the drive signal to the ultrasonic transducer for a predetermined period. 2. The ultrasonic actuator driving device according to 1.   The said control part changes the amplitude of the drive signal applied to the said ultrasonic transducer | vibrator gradually, when generating a bending vibration in the said ultrasonic transducer | vibrator, The Claim 3 thru | or 5 characterized by the above-mentioned. The ultrasonic actuator drive device according to one.   The said control part changes the frequency of the drive signal applied to the said ultrasonic transducer | vibrator gradually when generating a bending vibration in the said ultrasonic transducer | vibrator, The Claim 3 thru | or 5 characterized by the above-mentioned. The ultrasonic actuator drive device according to one. An ultrasonic actuator comprising an ultrasonic transducer formed by alternately laminating piezoelectric layers and internal electrode layers, and a driven body that moves relative to at least a portion of the ultrasonic transducer, Ultrasonic actuator driving method for driving the ultrasonic vibrator by generating a longitudinal vibration and / or a bending vibration by applying a two-phase driving signal generated based on an AC signal to the ultrasonic vibrator Because
An ultrasonic actuator driving method characterized by gradually changing a driving force applied to the driven body by switching a vibration state of the ultrasonic vibrator when starting or stopping the driven body.   When starting the driven body, the phase difference between the two-phase drive signals is controlled so that longitudinal vibration and bending vibration are generated after only the bending vibration is generated in the ultrasonic transducer. The method for driving an ultrasonic actuator according to claim 8.   When decelerating and stopping the driven body being driven, a driving force applied to the driven body is combined by combining a plurality of periods in which application of the drive signal to the ultrasonic transducer is stopped and periods in which bending vibration is generated. The method for driving an ultrasonic actuator according to claim 8, wherein: is gradually changed.   9. The method according to claim 8, wherein when the driven body being driven is decelerated and stopped, the application of the drive signal is stopped after only a bending vibration is generated in the ultrasonic vibrator for a predetermined period. Ultrasonic actuator driving method.   9. The method according to claim 8, wherein when the driven body being driven is decelerated and stopped, bending vibration is generated after application of the drive signal to the ultrasonic transducer is stopped for a predetermined period. Sonic actuator driving method.   13. The method according to claim 10, wherein an amplitude of a drive signal applied to the ultrasonic transducer is gradually changed when the bending vibration is generated in the ultrasonic transducer. Sonic actuator driving method.   13. The method according to claim 10, wherein when the bending vibration is generated in the ultrasonic transducer, a frequency of a drive signal applied to the ultrasonic transducer is gradually changed. Sonic actuator driving method.

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