JPH05276771A - Ultrasonic actuator - Google Patents

Abstract

PURPOSE:To provide a small-sized light-weight ultrasonic actuator, which includes a driver circuit capable of being driven by the power supply of low voltage and having excellent power supply efficiency and simple constitution and cost of which is reduced. CONSTITUTION:In an ultrasonic actuator, vibrational displacement is excited on the side face of a piezoelectric vibrator 1 and a mobile brought into contact with the piezoelectric vibrator 1 is moved by vibrations when the columnar piezoelectric vibrator 1 is supplied with high-frequency power. An electrode on one end face is divided into an electrode D and an electrode F. When voltage having frequency approximately the same as the resonance frequency of the piezoelectric vibrator 1 is applied to the electrode D, voltage having phase different by 180 deg. appears in the electrode F, and is fed back to the base of a transistor Q1. A self-excited oscillator using the transistor Q1 as an amplifying element and the piezoelectric vibrator 1 as a resonance circuit is constituted. A DC power supply E is boosted by quintuple, and voltage of 100Vp-p is applied to the piezoelectric vibrator 1 at the time of 20V voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic actuator, which is attracting attention as a compact actuator requiring high torque, such as a card feeding mechanism in a magnetic reader and a curtain feeding mechanism in a curtain remote opening / closing device.

[0002]

2. Description of the Related Art The basic principle of an ultrasonic motor is to transmit elastic vibration generated by a vibrator to a movable body through a frictional force and give a unidirectional driving force to the movable body. At this time, the displacement on the oscillator surface generally describes an elliptical activation. In the traveling wave type ultrasonic motor, the traveling wave is excited by the elastic body, and the mass point on the surface thereof draws an elliptical activation, so that a driving force in one direction is generated in the movable body. Traveling-wave ultrasonic motors have been put to practical use in camera auto-focus mechanisms and the like. However, the traveling wave type ultrasonic motor has a problem that when it is applied to a linear motion, the scale of the vibration system becomes large and the efficiency becomes low.

The traveling wave type ultrasonic linear motor is a method of exciting a traveling wave on the rod by providing piezoelectric vibrators at both ends of the rod. The traveling wave becomes complete by selecting the load resistance of the receiving side oscillator, and the traveling wave can be switched by exchanging the transmitted wave and the received wave. However, this method has a problem that the scale of the vibration system is large and the efficiency is low.

As a typical ultrasonic linear motor of the type utilizing a standing wave, there is one utilizing a rectangular flat plate-shaped piezoelectric vibrator. In that case, the primary resonance mode and the bending resonance mode of the longitudinal vibration which is the standing wave of the vibrator are used.
The unidirectional driving force is obtained from the elliptical movement of the end of the linear metal flat plate adhered to the vibrator, and the roller is pressed against this portion to obtain rotational power. This system can be miniaturized and can be expected to be applied to a paper feeding device or the like, but there is a problem that a two-phase high frequency power source is required.

The inventor of the present application was filed in Japanese Patent Application No. 63-129122.
The ultrasonic actuator filed in No. 1 has an extremely simple structure and can be easily miniaturized. Moreover, the power supply to the piezoelectric vibrator is sufficient for a single phase, and the control of the rotation direction is also very easy. have. The ultrasonic actuator is composed of a piezoelectric vibrator and a rotor, and the driving method of the ultrasonic actuator uses a combination of longitudinal vibration and radial vibration of the piezoelectric vibrator, which is generated on the side surface of the piezoelectric vibrator. Rotational power is applied to the rotor in contact with the piezoelectric vibrator by elastic vibration. By the way, in spite of the small size of the ultrasonic actuator, a relatively complicated circuit structure is required to drive the ultrasonic actuator, and a high DC voltage power supply is required. Further, there is a problem in efficiency regarding power consumption. In addition, there are problems in the number of parts constituting the circuit, the weight of the parts, and the price of the parts. That is, the smaller the ultrasonic actuator and the better its performance, the smaller the circuit for driving the ultrasonic actuator needs to be, and the higher the performance is.

A drive circuit for a piezoelectric vibrator, which is a drive source for the ultrasonic actuator, generates a high frequency high voltage,
Moreover, it is necessary to track the resonance frequency of the piezoelectric vibrator. This is because the resonance frequency of the piezoelectric vibrator changes due to changes in temperature or load. Specifically, the resonant frequencies of the cylindrical piezoelectric vibrators having diameters of 10 mm and 5 mm are about 140 kHz and 280 kHz, respectively, and the applied voltage is in the range of 20 to 130 Vp-p. When applied to the piezoelectric vibrator, the strength of vibration displacement on the side surface of the piezoelectric vibrator saturates, and at a voltage lower than this, the rotor in contact with the piezoelectric vibrator stops. The maximum power is about 3W. 14
Shows the results of measuring changes in surface temperature and resonance frequency in an operating state of a cylindrical piezoelectric vibrator having a diameter of 10 mm. The piezoelectric vibrator is driven by a three-terminal type self-exciting circuit described later, and a platinum resistor is used for temperature measurement. It can be seen that the resonance frequency fluctuates by 1 kHz with time. In addition to this, the resonance frequency of the piezoelectric vibrator changes due to various factors including the fluctuation of the load load of the piezoelectric vibrator.

On the other hand, the vibration displacement generated on the side surface of the piezoelectric vibrator is strong at the resonance frequency, and weak outside the resonance frequency. Therefore, it is desired that the drive circuit for efficiently exciting the piezoelectric vibrator has a function of tracking the resonance frequency. That is, the drive circuit of the ultrasonic actuator must satisfy the specifications such as resonance frequency, voltage, and power, and at the same time, have an automatic tracking function of resonance frequency.

There are two methods for the principle of frequency automatic tracking in the drive circuit that can automatically track the output frequency to the resonance frequency of the piezoelectric vibrator. The first method is an automatic tracking oscillation method. The automatic tracking oscillation method is a method of detecting the resonance frequency of the piezoelectric vibrator and automatically shifting the frequency of the oscillator to match the resonance frequency.
A PLL (Phase Locked Loop) system is often used.
The second method is a self-excited oscillation method. The self-excited oscillation method employs a circuit configuration in which oscillation and voltage / power amplification are integrated, and it is a method of oscillating by utilizing the resonance of a piezoelectric vibrator without having its own oscillation circuit inside. 11 to 13
Shows a conventional circuit example.

[0009]

FIG. 11 shows a case where a cylindrical piezoelectric vibrator is driven by a CR coupling amplifier circuit.
The CR coupling amplifier circuit has a problem that the DC voltage drop across the resistor R1 is large and the utilization of the power source is poor. In addition, since the power supply voltage becomes the drive voltage of the piezoelectric vibrator as it is, there is a drawback that a power supply of high DC voltage is required.

FIG. 12 shows a case where a cylindrical piezoelectric vibrator is driven by a DC-AC inverter circuit which is often used in a switching power supply circuit and a power supply for ultrasonic equipment.
The DC-AC inverter circuit has an advantage that it can be driven at a low voltage (a cylindrical piezoelectric vibrator can be driven with a power supply voltage of 2V), but the loss in the transformer is large compared to the power consumption of the cylindrical piezoelectric vibrator. , There is a problem in terms of efficiency.

FIG. 13 shows a case where a cylindrical piezoelectric vibrator is driven by a transformer coupling amplifier circuit. The transformer coupling amplifier circuit has poor frequency characteristics in the high frequency range, and there are problems of the price and weight of the transformer T1.

Further, the above-mentioned automatic tracking oscillation system using the PLL has a drawback that a complicated and expensive circuit is required.

Therefore, an object of the present invention is to receive electric power from a power source having a voltage lower than the required drive voltage of the piezoelectric vibrator and output high frequency AC power of the required drive voltage, and further, it is excellent in power efficiency and has a simple circuit configuration. The purpose is to provide an ultrasonic actuator that is inexpensive, inexpensive, and compact and lightweight.

[0014]

An ultrasonic actuator according to a first aspect of the present invention is a side surface of a piezoelectric ceramic by exciting a piezoelectric vibrator in which electrodes A and B are provided on both end surfaces of a columnar piezoelectric ceramic, respectively. In an ultrasonic actuator for transmitting a vibration displacement generated in a contact body which is in direct contact with a side surface of the piezoelectric ceramic or in contact with a coating covering the side surface, a polarization axis of the piezoelectric ceramic is Of the electrodes A and B, at least the electrodes A are perpendicular to both end faces and are insulated from each other.
And a circuit for driving the piezoelectric vibrator by applying a voltage having a frequency substantially equal to the resonance frequency of the piezoelectric ceramic between the electrode B and the electrode A1 or A2. , The drive circuit includes the electrode A
1 or A2, which receives an output voltage, and which receives as a feedback voltage the piezoelectricity that appears in the electrode of the electrodes A1 or A2 that is not supplied with the output voltage, and the output of the transistor. A voltage boosting coil connected between a voltage terminal and one terminal of a power source; and the drive circuit constitutes an oscillation circuit using the transistor as an amplification element and the piezoelectric vibrator as a resonance circuit. It is characterized by doing.

According to another aspect of the ultrasonic actuator of the present invention, the driving circuit outputs an AC pulse voltage as an excitation voltage to be supplied to the piezoelectric vibrator, and adjusts the voltage value of the AC pulse voltage. Means for adjusting the pulse width and pulse repetition frequency of the AC pulse voltage.

An ultrasonic actuator according to a third aspect of the present invention is characterized in that the moving direction of the contact body moved by the piezoelectric vibrator is parallel to the direction of the polarization axis of the piezoelectric ceramic.

An ultrasonic actuator according to a fourth aspect of the invention is characterized in that the moving direction of the ultrasonic actuator, which moves by contacting the contact body, is parallel to the direction of the polarization axis of the piezoelectric ceramic.

An ultrasonic actuator according to a fifth aspect is characterized in that an area ratio of the electrodes A1 and A2 on the end face is substantially equal to one.

An ultrasonic actuator according to a sixth aspect of the present invention is characterized in that the piezoelectric ceramic is a column having a dimensional ratio of diameter to height of approximately 1.

The ultrasonic actuator according to a seventh aspect of the present invention is characterized in that the piezoelectric ceramic is a rectangular prism having a dimensional ratio of at least two sides of three sides being substantially equal to 1.

[0021]

The operation circuit of the ultrasonic actuator of the present invention is
A self-excited circuit is adopted so that the frequency can be automatically tracked to the resonance frequency of the piezoelectric vibrator. In addition, a circuit using the counter electromotive voltage of the coil (hereinafter referred to as a counter electromotive voltage circuit) is provided so that the piezoelectric vibrator can be driven at a voltage higher than the power supply voltage. This circuit uses the characteristics of the coil to generate a high voltage, which is advantageous in price, weight, and volume as compared with the use of a transformer. Further, it is possible to bring features such as a simple circuit, a small size, and good power supply efficiency and frequency characteristics.

FIG. 9 shows a block diagram of a three-terminal self-exciting circuit. The three-terminal system has three terminals for connection with the piezoelectric vibrator, and each terminal is used for the purpose of being independent of each other. The electrode (the above-mentioned electrode A) on one side of the cylindrical piezoelectric vibrator is a drive electrode D (the above-mentioned electrode A1) for applying a voltage, and the feedback electrode F (the above-mentioned electrode A2) for feeding back a part of electric power to the amplifier. )
The other electrode (the above-mentioned electrode B) is grounded as a ground electrode G.

In this system, since the phase is shifted by 180 ° by the power amplifier, self-excited oscillation occurs at the frequency at which the phase is shifted by 180 ° between the D electrode and the F electrode of the piezoelectric vibrator.
The frequency at which the piezoelectric vibrator exhibits such characteristics is axisymmetric 1
It is the next resonance frequency.

FIG. 10 shows the result of measurement using a network analyzer on how the phase difference between the sine wave voltage applied to the D electrode and the voltage induced at the F electrode changes with frequency. However, a 50Ω load is connected to the F electrode in order to make the same conditions as in the self-excited circuit. The solid line shows the phase difference and the broken line shows the frequency characteristic of impedance. As shown in the figure, it can be seen that the phase difference becomes about 180 ° at the resonance frequency of the axially antisymmetric primary vibration. This indicates that the three-terminal self-excited circuit oscillates at the axially antisymmetric primary resonance frequency.

[0025]

1 is a sectional view showing an embodiment of an ultrasonic actuator of the present invention. In this embodiment, the ultrasonic actuator including the cylindrical piezoelectric vibrator 1 and the drive circuit unit 2 is housed inside the main body together with the slider 3, the moving body 4, the support 5, the support 6, the bearing 7, and the spring 8. Has been. A drive electrode D and a feedback electrode F are provided on one end surface of the piezoelectric vibrator 1, and a ground electrode G (not shown in the figure) is provided on the other end surface. The upper portion of the slider 3 can be moved linearly by contacting the bearing 7. The moving body 4 is made of a friction material and is fixed to the slider 3 with an adhesive. The piezoelectric vibrator 1 and the moving body 4 are pressed against each other by a spring 8. In this way, by applying a voltage to the piezoelectric vibrator 1 by the drive circuit unit 2, it is possible to generate a vibration displacement on the side surface of the piezoelectric vibrator 1, and the moving body 4 is moved by the vibration displacement. .. However, in FIG. 1, the terminals for applying a voltage to the piezoelectric vibrator 1 are omitted. The piezoelectric vibrator 1 is supported by a support 5 and a support base 6 made of sponge. Since the support base 6 is made of sponge, the adhesion between the piezoelectric vibrator 1 and the moving body 4 can be improved, and the vibration of the piezoelectric vibrator 1 itself can be prevented from being restrained.

FIG. 2 is a side view of the ultrasonic actuator of FIG. The moving body 4 can move linearly in the direction of the arrow. By providing the drive circuit unit 2 with means for switching the traveling direction of the moving body 4, the moving body 4 can repeat a linear motion.

3 and 4 are diagrams showing the relationship between the traveling direction of the moving body 4 and the electrodes of the piezoelectric vibrator 1. As shown in FIG. HI and L
O indicates the polarity of the applied voltage. When the switch is switched to the position a, the moving body 4 moves in the A direction, and when the switch is switched to the position b, the moving body 4 moves in the B direction. FIG. 3 shows a case where only one electrode of the piezoelectric vibrator 1 is divided into two. In this case, there is an advantage that only one relay circuit is required for switching. FIG. 4 shows a case where both electrodes of the piezoelectric vibrator 1 are divided into two. In this case, two relay circuits are required, but the speed difference depending on the moving direction of the moving body 4 can be reduced as compared with the circuit of FIG. The moving direction of the moving body 4 of the ultrasonic actuator shown in FIG. 1 can be controlled by using either of the means shown in FIGS. 3 and 4.

FIG. 5 is a diagram showing an embodiment of the drive circuit section 2 of the ultrasonic actuator shown in FIG. 1, which is a three-terminal system self-exciting circuit. The drive electrode D of the cylindrical piezoelectric vibrator 1 is connected to the collector of the transistor Q1, the feedback electrode F is connected to the base, and the electrode G on the other side is connected to the ground. When a voltage is applied to electrode D,
A negative phase voltage is induced in the electrode F, and this voltage is fed back to the base of Q1 via the resistor R1 to cause positive feedback self-excited oscillation.

R1 is a starting resistor for automatically causing self-excited oscillation when the power is turned on. If R1 is not present when the self-excited oscillation grows after the power is turned on, the electric charge induced from the electrode F is generated. There is little and it does not reach to turn on Q1. When self-sustained pulsation continues, a large amount of charge is induced from electrode F, so R1
Removing it has no effect. R2 and D1 are for protecting Q1, R2 is for limiting the base current, and D1 is for limiting the reverse voltage.

FIG. 6 shows waveforms during self-oscillation at the points of and in FIG. The power supply voltage E at this time is 2
It is 0V. It can be confirmed that the voltage boosted to about 100 V is applied to the piezoelectric vibrator 1 by the counter electromotive voltage generated by the coil L1 and that the waveforms thereof are in the opposite phase.

FIG. 7 shows the voltage of the electrode D and the current flowing through the coil L1 in the self-sustained pulsation continuous state. The measurement conditions in this case are that the piezoelectric vibrator 1 is a cylindrical piezoelectric vibrator having a diameter of 10 mm, the power supply voltage is 20 V, and the direct current flowing from the power supply is 65 mA. In periods A to D shown in FIG. 7, in periods A and D, electric power is accumulated in L1 and period B
In and C, the piezoelectric vibrator 1 consumes power.

Table 1 shows the approximate power consumption and power supply efficiency of the three-terminal system self-exciting circuit. The power consumption in the table is obtained from the product of the voltage of the DC power supply E and the DC current, and is the power consumed by the three-terminal system self-exciting circuit including the cylindrical piezoelectric vibrator 1. Most of the electric power stored in L1 is the piezoelectric vibrator 1.
However, it is considered that a part is used as electric power for turning on Q1. The power loss in the resistor R3 for current measurement is calculated by approximating the current waveform to a triangular wave. The power loss such as the ON resistance of Q1 and the resistance components of the starting resistances R1 and L1 is obtained by subtracting the power accumulated in L1 and the power loss in R3 from the power consumption.
The power supply efficiency is obtained by dividing the power consumed by the piezoelectric vibrator 1 by the input power excluding the power loss in R3 which is not used in the actual self-exciting circuit. Here, the power supply efficiency is calculated assuming that the electric power stored in L1 is entirely consumed by the piezoelectric vibrator.

Generally, the efficiency of the DC power supply is 30 to 60% for the series regulator and 70 to 85% for the switching regulator. From this, it is understood that the power supply efficiency of the embodiment of the present invention is as high as that of the switching regulator system. To further increase the efficiency, measures such as thickening the winding of the coil L1 to reduce the resistance amount and selecting a transistor Q1 having a low on-resistance can be considered.

Table 1 Power consumption of three-terminal circuit () shows the ratio to power consumption ──────────────────────────────── ─── Power consumption 1.3W Power consumption of resistance R3 for current measurement ・ ・ ・ 0.38W (29%) Loss due to ON resistance of Q1 and resistance of L1 0.24W (18 %) Electric power accumulated in L1 ... 0.68W (52%) Power efficiency 74% ─────────────────── ───────────────

In the embodiment of FIG. 1, a drive voltage of 100 Vp-p was obtained when the voltage of the power source E was 20 V, and a power source efficiency as high as 74% comparable to that of a switching regulator was obtained. Moreover, the circuit of this embodiment has one coil,
It can consist of very few components, one transistor, two resistors, and one diode. Further, the coil L1 is used for boosting the power supply voltage, and no transformer is used. The coil L1 is smaller, lighter, and cheaper than a transformer. In the present embodiment, as is clear from the above, the piezoelectric vibrator 1 can be driven with the peak voltage that is 5 times the power supply voltage. The minimum voltage that can drive the piezoelectric vibrator 1 is 20
Since it is Vp-p, the piezoelectric vibrator 1 can be driven if the power supply voltage E is 4 V or more. The ability to drive the piezoelectric vibrator with a low power supply voltage is extremely effective in widening the applications of the ultrasonic actuator.

FIG. 8 shows the results of examining the electrode shape suitable for the three-terminal system self-exciting circuit adopted in the driving circuit of the ultrasonic actuator of the present invention. The horizontal axis represents the power supply voltage E of the self-excited circuit of the three-terminal system, and the vertical axis represents the moving speed of the moving body 4. The moving speed is 2: 1 for the electrode with the electrode diameter divided into two equal parts.
It is clear that it is faster than the divided into.
This is because, in the three-terminal system, self-oscillation occurs in the axial antisymmetric primary vibration mode, and therefore, in the three-terminal system, the electrode shape having stronger axial antisymmetry is more advantageous. From the geometrical relationship, it can be understood that 1: 1 has stronger axial antisymmetry than dividing the electrode into 2: 1. Further, it is difficult to further enhance the axial anti-symmetry by reducing the electrode area, and to realize high speed by this. This is because the reduction of the electrode area increases the impedance, making it difficult to realize stable self-sustained pulsation. As a result, it can be seen that it is necessary to secure a certain electrode area.

Although the ultrasonic actuator using the cylindrical piezoelectric vibrator has been described above, it is clear that the present invention can also drive a prismatic piezoelectric vibrator.

[0038]

As described above in detail with reference to the embodiments, according to the present invention, the high frequency AC power of the required driving voltage is obtained by receiving the DC power from the power source of the voltage lower than the required driving voltage of the piezoelectric vibrator. Can be output, and is excellent in power efficiency,
It is possible to provide an ultrasonic actuator that has a simple circuit configuration, is inexpensive, and is small and lightweight. Moreover, the drive circuit is a drive circuit that can cope with environmental changes such as external temperature.

In the ultrasonic actuator of the present invention comprising a piezoelectric vibrator and a drive circuit, the movement direction of the contact body in contact with the piezoelectric vibrator is the direction of the polarization axis of the piezoelectric ceramic forming the piezoelectric vibrator. Being parallel, this contact body can make a linear movement along the direction of the polarization axis of the piezoelectric ceramic. Further, by using a friction material having excellent wear resistance as the contact body, the vibration displacement of the piezoelectric vibrator can be transmitted to the contact body without waste, and the controllability of the piezoelectric vibrator with respect to the contact body is improved. be able to.

In the ultrasonic actuator of the present invention composed of a piezoelectric vibrator and a drive circuit, in addition to the above-mentioned method in which the ultrasonic actuator is fixed and the contact body is moved, the contact body is reversely arranged. There is a method of moving the ultrasonic actuator itself while fixing it. In this case, the ultrasonic actuator moves itself by the vibration displacement of the piezoelectric vibrator, and its moving direction is parallel to the direction of the polarization axis of the piezoelectric ceramic.

Further, means for adjusting the voltage value of the AC pulse voltage by outputting an AC pulse voltage as the excitation voltage to be supplied to the piezoelectric vibrator, and means for adjusting the pulse width and the pulse repetition frequency of the AC pulse voltage. Since it is provided in the drive circuit, it is possible to control the moving distance and moving direction of the moving body in a very precise stepwise manner.
It is also possible to move a minute distance.

The ultrasonic actuator drive circuit of the present invention is not only compact and lightweight and can be driven with low power consumption, but it is also capable of low-speed and high-torque drive without noise, so that no gear is required. Further downsizing and weight reduction can be realized. Moreover, since it is not necessary to use a magnet, it can be used in a strong magnetic field. Furthermore, since it is possible to move itself with respect to the contact body, remote control by remote control is also possible, and it can be used in a narrow space where humans cannot enter, in liquids, or in dangerous places.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of an ultrasonic actuator of the present invention.

FIG. 2 is a side view of the ultrasonic actuator of FIG.

FIG. 3 is a diagram showing a relationship between a traveling direction of a moving body 4 and electrodes of the piezoelectric vibrator 1.

FIG. 4 is a diagram showing a relationship between a traveling direction of a moving body 4 and electrodes of the piezoelectric vibrator 1.

5 is a diagram showing an embodiment of a drive circuit unit 2 of the ultrasonic actuator of FIG.

6 is a diagram showing an oscilloscope voltage waveform observed for the circuit of FIG.

7 is a diagram showing waveforms of current and voltage in the embodiment of FIG.

8 is a diagram showing the relationship between the shape of electrodes in the piezoelectric vibrator 1 of the ultrasonic actuator of FIG. 1 and the moving speed of the moving body 4. FIG.

FIG. 9 is a diagram showing a basic configuration of a drive circuit that self-excitedly oscillates in a three-terminal system.

10 is a diagram showing frequency characteristics of voltage phase difference between electrodes D and F and impedance of electrode D regarding the piezoelectric vibrator in the circuit of FIG.

FIG. 11 is a diagram showing an example of a conventional self-excited drive circuit.

FIG. 12 is a diagram showing an example of a conventional self-excited drive circuit.

FIG. 13 is a diagram showing an example of a conventional self-excited drive circuit.

FIG. 14 is a diagram showing changes over time in surface temperature and resonance frequency in a cylindrical piezoelectric vibrator.

[Explanation of symbols]

 1 Piezoelectric vibrator 2 Drive circuit section 3 Slider 4 Moving body 5 Supporting tool 6 Supporting base 7 Bearing 8 Spring D, F, G electrode D1 diode E DC power supply L1 step-up coil Q1 transistor R1, R2 resistance

Claims (7)

[Claims] 1. A vibration displacement generated on a side surface of the piezoelectric ceramic by directly exciting the piezoelectric vibrator having electrodes A and B on both end surfaces of the columnar piezoelectric ceramic is brought into direct contact with the side surface of the piezoelectric ceramic. In the ultrasonic actuator for transmitting to a contact body which is in contact with a coating applied to or covered on the side surface, a polarization axis of the piezoelectric ceramic is perpendicular to the both end surfaces, and And at least the electrode A is divided into electrodes A1 and A2 which are insulated from each other, and by applying a voltage having a frequency substantially equal to the resonance frequency of the piezoelectric ceramic between the electrode B and the electrode A1 or A2, A circuit for driving the piezoelectric vibrator is provided, and the drive circuit supplies an output voltage to one of the electrodes A1 or A2, and the driving circuit supplies the output voltage to one of the electrodes A1 or A2. A transistor for receiving as a feedback voltage the piezoelectricity appearing on the electrode to which the output voltage is not supplied, and a voltage booster connected between the output voltage terminal of the transistor and one terminal of the power supply. An ultrasonic actuator comprising: a coil, wherein the drive circuit forms an oscillation circuit in which the transistor is an amplification element and the piezoelectric vibrator is a resonance circuit. 2. The driving circuit outputs an AC pulse voltage as an excitation voltage to be supplied to the piezoelectric vibrator, a means for adjusting a voltage value of the AC pulse voltage, and a pulse width and a pulse repetition of the AC pulse voltage. The ultrasonic actuator according to claim 1, further comprising: a means for adjusting a frequency. 3. The ultrasonic actuator according to claim 1, wherein a moving direction of the contact body moved by the piezoelectric vibrator is parallel to a direction of a polarization axis of the piezoelectric ceramic. 4. The ultrasonic actuator according to claim 1, wherein a moving direction of the piezoelectric body which is moved by contacting the contact body is parallel to a direction of a polarization axis of the piezoelectric ceramic. 5. The area ratio of the electrodes A1 and A2 on the end face is approximately equal to 1, 2.
The ultrasonic actuator according to 3 or 4. 6. The ultrasonic actuator according to claim 1, wherein the piezoelectric ceramic is a cylinder having a dimensional ratio of diameter to height that is substantially equal to 1. 7. The ultrasonic wave according to claim 1, wherein the piezoelectric ceramic is a rectangular prism whose dimensional ratio of at least two sides among three sides is substantially equal to 1. Actuator.