JPH08289574A - Ultrasonic actuator - Google Patents

Abstract

PURPOSE: To provide an ultrasonic actuator which consists of a piezoelectric oscillator, an oscillation plate, an oscillation bar, and a mover, and making the piezoelectric oscillator generate oscillatory displacement on the surface of the oscillation bar by exciting the elastic oscillation, and moves the mover by the oscillatory displacement. CONSTITUTION: Driving a complex consisting of a piezoelectric oscillator 1, an oscillation plate 2, and an oscillation bar by the use of an self exciting drive circuit will excite the elastic oscillation of the piezoelectric oscillator. The oscillation plate 2 is oscillated in the shape that the junction area with the piezoelectric oscillator 1 becomes its fixed end, accompanying the oscillation of the piezoelectric oscillator 1. This oscillation oscillates the oscillation bar 3, and oscillatory displacement occurs on the surface of the oscillation bar 3. This oscillatory displacement moves the mover 4. Accordingly, low power consumption drive is possible with its construction simple, its size and weight small and light, and its circuit constitution simple, and its voltage low.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a piezoelectric vibrator, a vibrating plate, a vibrating rod, and a movable body. By exciting elastic vibration in the piezoelectric vibrating device, a vibration displacement is generated on the surface of the vibrating rod.
The present invention relates to an ultrasonic actuator that moves a movable body by its vibration displacement.

2. Description of the Related Art The basic principle of a conventional ultrasonic motor is that elastic vibration generated by a vibrator is transmitted to a movable body through a frictional force to give a unidirectional driving force to the movable body. . At this time, the displacement on the surface of the oscillator 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 elliptic activation, so that a driving force in one direction is generated in the movable body. The traveling wave type ultrasonic motor has been put to practical use in an autofocus mechanism of a camera, etc., but when it is applied to a linear motion, it has a problem that the efficiency decreases because the scale of the vibration system becomes large. A typical example of a type of ultrasonic linear motor that uses a standing wave is one that uses a rectangular flat plate-shaped piezoelectric vibrator. 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 has a problem that a two-phase high frequency power source is required. In this way,
The conventional ultrasonic motor has problems that the efficiency decreases because the scale of the vibration system becomes large, and that it requires a relatively complicated circuit configuration even if it can be downsized. It was Above all, it has a drawback that the distance between the vibrator and the movable body is limited. That is, it is difficult to propagate the energy of the vibration to the movable body that is located away from the vibrator. Therefore, the application area was limited.

SUMMARY OF THE INVENTION An object of the present invention is to be able to simultaneously move a plurality of movable bodies located apart from a piezoelectric vibrator, and to have a simple structure, a small size and a light weight, a simple circuit configuration, and a low structure. An object is to provide an ultrasonic actuator that can be driven with low power consumption by voltage.

An ultrasonic actuator according to claim 1 comprises a piezoelectric vibrator, a vibration plate fixed to the piezoelectric vibrator, and at least one vibration rod fixed to the vibration plate. An ultrasonic actuator comprising: a movable body that is in contact with the surface of the vibrating rod or a coating that covers the surface, wherein the vibrating rod has an end fixed to one plate surface of the vibrating plate. Or a part of the side surface is fixed to a through hole that penetrates both plate surfaces of the vibration plate, and the piezoelectric vibrator includes a columnar piezoelectric ceramic, electrodes P and G,
The electrodes P and G are formed on both end surfaces perpendicular to the thickness direction of the piezoelectric ceramic, and the vibrating plate is integrally connected to the end surface having the electrodes P or G of the piezoelectric vibrator. Fixed to each other and projecting toward the outside of the piezoelectric vibrator substantially in parallel to the end face having the electrode P or G of the piezoelectric vibrator, and at least one set of the electrodes P and G has at least one electrode P. Of the interdigital transducers, the interdigital transducers comprising portions D and F, said portions D and F of said interdigital transducer being provided with terminals T _D and T _F, respectively, and said electrode G having terminals T _G is provided, and when a voltage having a frequency substantially equal to the resonance frequency of the piezoelectric vibrator is applied between the terminals T _D and T _G , elastic vibration is excited in the piezoelectric vibrator, The piezoelectric transducer The vibration frequency is substantially equal to the resonance frequency of the composite body composed of the piezoelectric vibrator, the vibration plate, and the vibration rod, and the elastic vibration is propagated to the vibration plate and the terminals T _F and T _G. It is characterized in that a vibration displacement is generated on the surface of the vibrating rod by the elastic vibration which is converted into an electric signal and outputted, and propagated to the vibration plate, and the vibration displacement moves the movable body. The ultrasonic actuator according to claim 2, wherein the piezoelectric vibrator is a rectangular plate having a length-width dimension ratio close to 1 and not equal to 1, or any two of length-width-thickness. It is characterized by being a rectangular prism having a dimensional ratio close to 1 and not equal to 1. The ultrasonic actuator according to claim 3 is characterized in that the area of the portion D on one end face of the piezoelectric ceramic is approximately twice the area of the portion F. The ultrasonic actuator according to claim 4, wherein the vibrating plate is integrally connected and fixed to a portion along the width direction of the piezoelectric vibrator on an end surface of the piezoelectric vibrator having the electrode G, and the terminal is provided. T _D and T _F are characterized in that they are provided in a portion along the width direction of the piezoelectric vibrator on the end face having the electrode P of the piezoelectric vibrator. The ultrasonic actuator according to claim 5, further comprising an oscillating circuit including a transistor as an amplifying element and a composite element including the piezoelectric vibrator, the vibrating plate and the vibrating rod as a resonating element, wherein the oscillating circuit is a direct current. The transistor includes a step-up coil connected between a power source V _dc and the terminal T _D, and the transistor has an output terminal of the transistor connected to the terminal T _D and an input terminal of the transistor connected to the terminal T _F. It is characterized in that the piezoelectricity appearing at the terminal T _F is received as a feedback voltage by being connected to. An ultrasonic actuator according to a sixth aspect of the present invention is characterized in that the vibrating rod has a linear shape, a curved shape, or a combination thereof. The ultrasonic actuator according to claim 7 is characterized in that the vibrating rod is branched into at least two. The ultrasonic actuator according to claim 8 is characterized in that the branched portion of the vibrating rod is branched into at least two. An ultrasonic actuator according to a ninth aspect is characterized in that the shape of a cross section of the vibrating rod perpendicular to the length direction is a square edge or an annular shape. Claim 10
The ultrasonic actuator described in (1) is characterized in that the movable body, which is brought into contact with the tip of the vibrating rod or the coating covering the tip, makes a rotational movement about the longitudinal direction of the vibrating rod. The ultrasonic actuator according to claim 11,
The movable body, which is in contact with a side surface of the vibrating rod or a coating covering the side surface, moves or repeatedly moves along the length direction of the vibrating rod.

The ultrasonic actuator of the present invention has a simple structure including a piezoelectric vibrator, a diaphragm, at least one vibrating rod, and a movable body. The vibrating plate is fixed to the piezoelectric vibrator, and the vibrating rod is fixed to the vibrating plate. The vibrating rod is fixed to one plate surface of the vibrating plate with the two ends being the tip and the end, or the end is a fixed end, or a part of the side surface is a through hole penetrating both plate surfaces of the vibrating plate. It is fixed. At this time, the vibrating rod is fixed to the vibrating plate so that the length direction of the vibrating rod and the direction of the plate surface of the vibrating plate are perpendicular to each other in the fixed portion between the vibrating rod and the vibrating plate. As long as the vibrating rod has an elongated shape, the length may be long or short whether it is bent or not, but at least in the fixed part between the vibrating rod and the vibrating plate, the vibrating rod vibrates in the longitudinal direction. A structure is adopted that is perpendicular to the plate surface of the plate. The piezoelectric vibrator is composed of a columnar piezoelectric ceramic and electrodes P and G, and the electrodes P and G are formed on both end surfaces perpendicular to the thickness direction of the piezoelectric ceramic. At this time, at least the electrode P of the electrodes P and G is a set of interdigital electrodes, and the interdigital electrode is composed of portions D and F. Portions D and F are provided with terminals T _D and T _F, respectively. The electrode G is provided with a terminal T _G. By applying a voltage having a frequency substantially equal to the resonance frequency of the piezoelectric vibrator between the terminals T _D and T _G , elastic vibration is excited in the piezoelectric vibrator. At this time, the resonance frequency of the piezoelectric vibrator is substantially equal to the resonance frequency of the composite body including the piezoelectric vibrator, the vibration plate, and the vibration rod. The elastic vibration in the piezoelectric vibrator vibrates the diaphragm, and the vibration of the diaphragm is propagated to the vibrating rod. In this way, vibrational displacement occurs on the surface of the vibrating rod. When the movable body is brought into direct contact with the tip or the side surface of the vibrating rod, or when the movable body is brought into contact with the coating covering the tip or the side surface of the vibrating rod, the movable body is moved by the vibration displacement in the vibrating rod. At this time, the movable body that is brought into contact with the tip of the vibrating rod or the coating covering the tip is
It makes a rotary motion about the length of the vibrating rod. Further, the movable body that is in contact with the side surface of the vibrating rod or the coating covering the side surface moves, rotates, or repeats along the length direction of the vibrating rod. For example, if an object having a plane is a movable body and the plane of the object is pressed against the side surface of the vibrating rod, the object moves along the length direction of the vibrating rod, and if the bearing is pressed, the bearing rotates and the V-shaped If you put the wire on a horizontal vibrating rod, it will move repeatedly. The movement direction of the movement, rotation, or repetitive movement can be controlled by changing the contact point between the vibrating rod and the movable body. As a coating that covers the surface of the vibrating rod, a material that produces a frictional force is used. Most of the elastic vibration in the piezoelectric vibrator is propagated to the vibrating rod through the vibrating plate and consumed to move the movable body. Further, elastic vibration in the piezoelectric vibrator is caused by the terminal T _F.
It is possible to output as an electrical signal from between T _G and T _G. Moreover, the electric signal output from between the terminals T _F and T _G can be input again between the terminals T _D and T _G. Such an ultrasonic actuator is not only capable of efficiently moving a movable body, but is also small and lightweight, can be driven by a self-excited type, and can be easily driven by a battery. It is possible to drive in a form that can respond to environmental changes. Further, in the ultrasonic actuator of the present invention, by adopting a structure in which the electrode P is composed of one set of interdigital electrodes, even when the thickness of the piezoelectric vibrator is thin, that is, the thickness of the piezoelectric vibrator is not affected by It is possible to perform efficient self-excited oscillation drive without being driven. The ultrasonic actuator of the present invention employs a self-excited oscillation circuit in order to realize efficient self-excited driving. This self-excited oscillation circuit is a circuit in which a transistor is used as an amplification element and a composite body including a piezoelectric vibrator, a vibration plate, and a vibration rod is used as a resonance element.
Further, a boosting coil is connected between the DC power supply V _dc and the terminal T _D. The output terminal of the transistor is terminal T
_The input terminal is connected to the terminal T _F and is connected to _D , and this transistor is for receiving the piezoelectricity appearing at the terminal T _F as a feedback voltage. In this way, the self-oscillation circuit is provided with the function of automatically tracking the frequency with the resonance frequency of the piezoelectric vibrator. In addition, by providing the circuit using the counter electromotive voltage of the coil, it becomes possible to drive the piezoelectric vibrator at a voltage higher than the DC power supply voltage. This counter electromotive voltage circuit generates a high voltage by utilizing the characteristics of the coil, and is advantageous in terms of price, weight and volume as compared with the use of a transformer. Further, it is possible to bring about features such as a simple circuit configuration and a small size, and good power supply efficiency and frequency characteristics. In the ultrasonic actuator of the present invention, as a piezoelectric vibrator, a rectangular plate having a length-width dimension ratio close to 1 and not equal to 1, or a dimension ratio of any two of length-width-thickness is 1. It is possible to employ a rectangular prism that is close to and not equal to 1. Therefore, the combined vibration of the composite body including the piezoelectric vibrator, the diaphragm, and the vibrating rod is enhanced, so that the energy of the ultrasonic wave is easily propagated to all the corners of the vibrating rod. The vibrating plate is integrally fixed on the end surface having the electrodes of the piezoelectric vibrator in a continuous manner, and further fixed to the end surface of the piezoelectric vibrator so as to project substantially parallel to the end surface of the piezoelectric vibrator. There is. Therefore, the vibrating plate vibrates with the joint between the piezoelectric vibrator and the vibrating plate as the fixed end, and the energy of this vibration can be efficiently propagated to the vibrating rod. In the ultrasonic actuator of the present invention, the vibrating plate is integrally connected and fixed to a portion along the width direction of the piezoelectric vibrator on the end face having the electrode G of the piezoelectric vibrator, and the terminal T
It is possible to employ a structure in which _D and _TF are provided in a portion along the width direction of the piezoelectric vibrator on the end face having the electrode P of the piezoelectric vibrator. That is, the vibrating plate is fixed to the portion along the width direction of the piezoelectric vibrator, and the terminals T _D and T _F are also provided in the portion along the width direction of the piezoelectric vibrator. That is, the portions D and F of the interdigital electrode P are arranged so that the terminals T _D and T _F are arranged in the portion along the width direction of the piezoelectric vibrator. By adopting such a structure, efficient self-excited driving becomes possible, and driving at low voltage and low power consumption becomes possible. Furthermore, by adopting a structure in which the area of the portion D on one end face of the piezoelectric ceramic is almost twice the area of the portion F, the piezoelectric electricity generated by the excitation of the piezoelectric vibrator itself and appearing at the terminal T _F. It is possible to improve the efficiency when the voltage is supplied to the terminal T _D again as a feedback voltage and used. Therefore, the power supply efficiency can be further improved. In the ultrasonic actuator of the present invention, the vibrating rod may have a linear rod shape, a curved rod shape, or a combination thereof. Also, a coiled structure can be adopted. That is, the vibrating rod does not have to be linear and may be bent. Moreover, the vibrating rod may or may not penetrate the upper and lower sides of the diaphragm. Further, it is also possible to adopt a structure in which the vibrating rod is branched into at least two, and it is also possible to adopt a structure in which the branched portion is further branched into at least two. That is,
The ultrasonic energy is sufficiently propagated to the branched tip portion. A structure in which the shape of the cross section perpendicular to the longitudinal direction of the vibrating rod is an annular shape, for example, a structure in which the shape of the cross section is an edge or an annular shape, that is, by adopting a tubular structure as the vibrating rod, The sound wave energy is more likely to be propagated to every corner of the vibrating rod. In the ultrasonic actuator of the present invention, the movable body contacting the tip of the vibrating rod or the coating covering the tip makes a rotational movement about the longitudinal direction of the vibrating rod. That is, energy is generated at the tip of the vibrating rod so that the dish can be turned. The movable body, which is brought into contact with the side surface of the vibrating rod or the coating covering the side surface, moves, rotates, or repeatedly moves along the length direction of the vibrating rod. For example, if an object having a flat surface is used as a movable body and the flat surface is pressed against the vibrating rod, the object moves along the length direction of the vibrating rod, and if the bearing is pressed, the bearing rotates and V-shaped or U-shaped wire Place it on a horizontal vibrating rod to make repetitive motion. The movement direction of this movement, rotation, or repetitive movement can be reversed by changing the position of the side surface of the vibrating rod that contacts the movable body.

1 is a side view showing an embodiment of an ultrasonic actuator of the present invention. In this embodiment, the piezoelectric vibrator 1, the diaphragm 2, the vibrating rod 3, the movable body 4, and the self-excited oscillation drive circuit 5 are used.
Consists of. However, in FIG. 1, the self-excited oscillation drive circuit 5 is omitted. The vibrating plate 2 is integrally fixed to one end surface of the piezoelectric vibrator 1 so as to be continuous with the piezoelectric vibrator 1. The vibrating rod 3 is fixed to the inner surface of a through hole that penetrates both plate surfaces of the vibrating plate 2. The piezoelectric vibrator 1 includes a piezoelectric ceramic 6, a comb-shaped electrode P and an electrode G. The interdigital electrode P has portions D and F.
And portions D and _F are provided with terminals T _D and T _F, respectively. The electrode G is provided with a terminal T _G. However, the portion F and the terminal T _F are not shown in FIG. The piezoelectric ceramic 6 is made of a rectangular plate-shaped TDK72A material (product name), and has a length of 17 mm, a width of 20 mm, and a thickness of 1 mm. The direction of the polarization axis of the piezoelectric ceramic 6 coincides with the thickness direction, the interdigital electrode P is formed on one end face perpendicular to the thickness direction, and the electrode G is formed on the other end face. . Each electrode is made of an aluminum thin film. The diaphragm 2 is made of stainless steel, and has a length of 23 mm, a width of 20 mm,
The thickness is 0.05 mm. The vibrating plate 2 has a bonding region having a length of 2 mm and a width of 20 mm at the end of one plate surface, and is fixed to a portion along the width direction on the end face having the electrode G of the piezoelectric vibrator 1. Further, the vibration plate 2 projects outward of the piezoelectric vibrator 1 substantially parallel to the end surface of the piezoelectric vibrator 1. That is, the protruding portion of the diaphragm 2 is 18 m long.
m, width 20 mm. The terminals T _D and T _F are provided at portions along the width direction of the piezoelectric vibrator 1. The vibrating rod 3 is made of a brass pipe, and the cross section perpendicular to the length direction has an outer diameter of 0.6 mm and an inner diameter of 0.2 mm. The movable body 4 is in contact with the side surface of the vibrating rod 3. The movable body 4 is a ball bearing. FIG. 2 is a perspective view showing another embodiment of the movable body 4. The movable body 7 in FIG. 2 is a dish with a diameter of 20 mm, and is placed on the tip of the vibrating rod 3. FIG. 3 is a perspective view showing yet another embodiment of the movable body 4. The movable body 8 in FIG. 3 is made of a V-shaped wire and is in contact with the side surface of the vibrating rod 3. At this time, whether the vibrating rod 3 is bent,
Alternatively, the apparatus is installed so that the vibrating rod 3 is substantially horizontal, so that the vibrating rod 3 is provided with a horizontal portion, and the movable body 8 is placed on the horizontal portion. FIG. 4 is a perspective view showing a composite body including the piezoelectric vibrator 1, the vibration plate 2 and the vibration rod 3 in the ultrasonic actuator of FIG. Although the vibrating rod 3 penetrates the diaphragm 2 in this embodiment, a structure in which it does not penetrate and is fixed on the plate surface of the diaphragm 2 is also possible. Figure 5
FIG. 3 is a plan view showing the piezoelectric vibrator 1. The interdigital electrode P has 6 pairs of electrode fingers, the electrode period length is 2 mm, and the electrode crossing width is 4.8 mm. The area of the portion D on one plate surface of the piezoelectric vibrator 1 is twice the area of the portion F. When the ultrasonic actuator of FIG. 1 is driven, when an electric signal having a frequency substantially equal to the resonance frequency of the composite body of FIG. 4 is input to the piezoelectric vibrator 1 via the terminals T _D and T _G , the piezoelectric vibrator 1 is piezoelectrically driven. The vibration is excited. Since the vibrating plate 2 is integrally fixed to one end surface of the piezoelectric vibrator 1, the vibrating plate 2 is bonded to the piezoelectric vibrator 1 as the piezoelectric vibrator 1 vibrates. It is vibrated with the area as the fixed end. This vibration vibrates the vibrating rod 3, and a vibration displacement is generated on the surface of the vibrating rod 3. This vibration displacement moves the movable body 4, 7 or 8. The vibrating rod 3 having a maximum length of about 1 m enables the movable body 4, 7 or 8 to move. FIG. 6 is a block diagram showing an embodiment of the self-excited oscillation drive circuit 5. Most of the vibration excited in the piezoelectric vibrator 1 by applying a voltage to the piezoelectric vibrator 1 via the terminals T _D and T _G is propagated to the vibration plate 2 and the vibration of the piezoelectric vibrator 1 is increased. The voltage is output from the terminals T _F and T _G as a voltage having a phase opposite to that of the voltage applied to the piezoelectric vibrator 1 according to the vibration. By repeating this operation, positive feedback self-excited oscillation occurs. That is, an electric signal having a frequency substantially equal to the resonance frequency of the composite body is stably supplied to the piezoelectric vibrator 1 following changes in the ambient temperature. In this way, it is possible to always maintain its own optimum oscillation state.
Therefore, the problem that the resonance frequency of the composite is deviated due to heat generation or the like, which is a problem during the separately-excited driving, and the oscillation condition is deteriorated, is solved. In addition, it is possible to configure the circuit with a very small number of components including one coil L ₁ , one transistor _Tr , two resistors R ₁ and R ₂ , and one diode D ₁ . Moreover, although the number of parts is small, the DC power supply V _dc can be used and the power efficiency is high, which enables downsizing of the power supply. When the ultrasonic actuator of FIG. 1 is driven, it was confirmed that the driving was at the lowest voltage and the lowest power consumption when the area of the portion D was almost twice the area of the portion F. In other words, it indicates that the movement efficiency of the movable body 4, 7 or 8 at this time is high.
For example, when the area ratio between the portions D and F was 2: 1, the power consumption was 0.6 W when the DC power supply voltage was 9V.
FIG. 7 is a characteristic diagram showing the relationship between the admittance peak between the terminals T _D and T _G in the composite of FIG. 4 and the area ratio of the portion D when the area of the portion F is 1. However, the admittance peak in FIG. 7 shows a value near the resonance frequency of the piezoelectric vibrator 1. The admittance peak shows the maximum value when the area of the portion D is almost twice the area of the portion F. FIG. 8 shows terminals T _D and T _G of the piezoelectric vibrator 1 alone or the composite of FIG.
It is a characteristic view which shows the relationship of the phase and frequency of the admittance between and. The dotted line shows the case of the piezoelectric vibrator 1 alone, and the solid line shows the case of the composite body. However, FIG. 8 shows two cases where the length of the protruding portion of the diaphragm 2 excluding the joint portion with the piezoelectric vibrator 1 is 22 mm and the length is 17.9 mm. When the length of the overhanging portion of the diaphragm 2 is 17.9 mm, one of the resonance frequencies of the composite (92.5 k
Hz) matches the resonance frequency of the piezoelectric vibrator 1 alone. FIG. 9 is a perspective view showing another embodiment of the composite body of FIG. This embodiment comprises a piezoelectric vibrator 9, a diaphragm 10 and a vibrating rod 11. The vibrating plate 10 is integrally fixed to the piezoelectric vibrator 9 on one end surface of the piezoelectric vibrator 9. The vibrating rod 11 is fixed to one plate surface of the vibrating plate 10. The piezoelectric vibrator 9 comprises a piezoelectric ceramic 12, a comb-shaped electrode P and an electrode G. The interdigital electrode P is composed of portions D and F, and the portions D and _F are provided with terminals T _D and T _F, respectively. The electrode G is provided with a terminal T _G. The area of the portion D on one plate surface of the piezoelectric vibrator 9 is twice the area of the portion F. The piezoelectric ceramic 12 is made of a rectangular prismatic TDK72A material (product name), and its length is 10
mm, the width is 5 mm, and the thickness is 6 mm. Piezoelectric ceramic 12
The direction of the polarization axis corresponds to the thickness direction, and the interdigital electrode P is formed on one end face perpendicular to the thickness direction and the electrode G is formed on the other end face. Each electrode is made of an aluminum thin film. The interdigital electrode P has six pairs of electrode fingers, and has an electrode cycle length of 1 mm and an electrode crossing width of 3.8 mm. The diaphragm 10 is made of stainless steel and has a length of 12 mm, a width of 5 mm and a thickness of 0.05 mm. The vibrating plate 10 has a length of 1.5 mm and a width of 5 mm at one end of the plate surface.
It has a bonding area of mm and is fixed to a portion along the width direction on the end surface of the piezoelectric vibrator 9 having the electrode G. Also,
The diaphragm 10 faces the outside of the piezoelectric vibrator 9
Project almost parallel to the end face of the. The terminals T _D and T _F are provided at portions along the length direction of the piezoelectric vibrator 9. The vibrating rod 11 is made of a brass rod having a length of 45 mm, and its cross section perpendicular to the length direction is a square having one side of 0.6 mm. The vibrating rod 11 can be freely bent. It was confirmed that the same effect as when using the composite shown in FIG. 4 was obtained when the composite shown in FIG. 9 was used.

The ultrasonic actuator of the present invention comprises a piezoelectric vibrator, a vibrating plate fixed to the piezoelectric vibrator, at least one vibrating rod fixed to the vibrating plate, and a movable member fixed to the vibrating rod. With. The piezoelectric vibrator includes a columnar piezoelectric ceramic, and electrodes P and G formed on both end surfaces of the piezoelectric ceramic which are perpendicular to the thickness direction. At this time, at least the electrode P of the electrodes P and G is a set of interdigital electrodes, and the interdigital electrode is composed of portions D and F. The portions D and F are provided with terminals T _D and T _F, respectively, and the electrode G is provided with a terminal T _G. Terminal T _D
By applying a voltage having a frequency substantially equal to the resonance frequency of the piezoelectric vibrator between T and T _G , elastic vibration is efficiently excited in the piezoelectric vibrator. At this time, the resonance frequency of the piezoelectric vibrator is substantially equal to the resonance frequency of the composite body including the piezoelectric vibrator, the vibration plate, and the vibration rod. By adopting the piezoelectric vibrator having such a simple structure, the ultrasonic actuator can be downsized. The elastic vibration of the piezoelectric vibrator vibrates the vibrating plate, and the vibration of the vibrating plate is propagated to the vibrating rod, causing vibrational displacement on the surface of the vibrating rod. When the movable body is brought into direct contact with the surface of the vibrating rod or the movable body is brought into contact with the coating covering the surface of the vibrating rod, the movable body is moved by the vibration displacement in the vibrating rod. As a coating that covers the surface of the vibrating rod, a material that produces a frictional force is used. Most of the elastic vibration in the piezoelectric vibrator is propagated to the vibrating rod through the vibrating plate and is consumed for moving the movable body, and at the same time, the terminals T _F and T _G
It is possible to output as an electric signal from between the terminals T _F and T _G, and the electric signal output from between the terminals T _F and T _G can be input again between the terminals T _D and T _G. Such an ultrasonic actuator not only can efficiently move a movable body, but also has a simple circuit configuration, is small and lightweight,
Since self-excited driving is possible, it is possible to drive in a form that can cope with environmental changes such as temperature rise due to heat generation. Further, by adopting a structure in which at least the electrode P is composed of one set of interdigital electrodes, even if the thickness of the piezoelectric vibrator is small, that is, the thickness of the piezoelectric vibrator does not affect the efficiency. Self-excited oscillation drive becomes possible. The ultrasonic actuator of the present invention employs an efficient self-excited oscillation drive circuit in which a transistor is used as an amplification element and a composite body including a piezoelectric vibrator, a diaphragm and a vibrating rod is used as a resonance element. Further, a boosting coil is connected between the DC power supply V _dc and the terminal T _D. The output terminal of the transistor is terminal T _D
And the input terminal is connected to the terminal T _F , and this transistor is for receiving the piezoelectricity appearing at the terminal T _F as a feedback voltage. In this way, this self-excited oscillation drive circuit is provided with the function of automatically tracking the frequency to the resonance frequency of the piezoelectric vibrator. In addition, by providing the circuit using the counter electromotive voltage of the coil, it becomes possible to drive the piezoelectric vibrator at a voltage higher than the DC power supply voltage. This counter electromotive voltage circuit generates a high voltage by utilizing the characteristics of the coil, and is advantageous in terms of price, weight and volume as compared with the use of a transformer. Further, it is possible to bring about features such as a simple circuit configuration and a small size, and good power supply efficiency and frequency characteristics.
In the ultrasonic actuator of the present invention, as a piezoelectric vibrator, a rectangular plate having a length-width dimension ratio close to 1 and not equal to 1, or a dimension ratio of any two of length-width-thickness is 1. It is possible to employ a rectangular prism that is close to and not equal to 1. Therefore, the combined vibration of the composite body including the piezoelectric vibrator, the diaphragm, and the vibrating rod is enhanced, so that the energy of the ultrasonic wave is easily propagated to all the corners of the vibrating rod. The vibrating plate is integrally fixed on the end surface having the electrodes of the piezoelectric vibrator in a continuous manner, and further fixed to the end surface of the piezoelectric vibrator so as to project substantially parallel to the end surface of the piezoelectric vibrator. There is. Therefore, the vibrating plate vibrates with the joint between the piezoelectric vibrator and the vibrating plate as the fixed end, and the energy of this vibration can be efficiently propagated to the vibrating rod. In the ultrasonic actuator of the present invention, the vibrating plate is integrally and integrally fixed to a portion along the width direction of the piezoelectric vibrator on the end surface having the electrode G of the piezoelectric vibrator, and the terminals T _D and T _F are piezoelectric vibrating. It is possible to employ a structure provided in a portion along the width direction of the piezoelectric vibrator on the end face having the child electrode P. That is, it is possible to adopt a structure in which the portions D and F of the interdigital electrode P are arranged such that the terminals T _D and T _F are arranged in the portions along the width direction of the piezoelectric vibrator. By adopting such a structure, efficient self-excited driving becomes possible, and driving at low voltage and low power consumption becomes possible. Furthermore, by adopting a structure in which the area of the portion D on one end face of the piezoelectric ceramic is almost twice the area of the portion F, the piezoelectric electricity generated by the excitation of the piezoelectric vibrator itself and appearing at the terminal T _F. Since it becomes possible to improve the efficiency when the voltage is supplied to the terminal T _D again as a feedback voltage and used, the power supply efficiency can be further improved. In the ultrasonic actuator of the present invention, the vibrating rod may have a linear rod shape, a curved rod shape, or a combination thereof. That is, the vibrating rod does not have to be linear and may be bent. Further, a branched structure can be adopted as the vibrating rod. The ultrasonic energy is sufficiently propagated to the branched tip portion. By adopting a structure in which the cross section perpendicular to the longitudinal direction of the vibrating rod is, for example, a rim or an annular shape, that is, adopting a tubular structure as the vibrating rod, the ultrasonic energy is further applied to the tip of the vibrating rod. It becomes easy to be propagated up to. In the ultrasonic actuator of the present invention, the movable body contacting the tip of the vibrating rod or the coating covering the tip makes a rotational movement about the longitudinal direction of the vibrating rod. That is,
Energy is generated at the tip of the vibrating rod so that the dish can be turned. The movable body, which is brought into contact with the side surface of the vibrating rod or the coating covering the side surface, moves, rotates, or repeatedly moves along the length direction of the vibrating rod. For example, if an object having a flat surface is used as a movable body and the flat surface is pressed against the vibrating rod, the object moves along the length direction of the vibrating rod, and if the bearing is pressed, the bearing rotates and V-shaped or U-shaped wire Place it on a horizontal vibrating rod to make repetitive motion. This move,
The direction of rotation or repetitive motion can be reversed by changing the position of the side surface of the vibrating rod that contacts the movable body.

[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 perspective view showing another embodiment of a movable body 4.

FIG. 3 is a perspective view showing still another embodiment of the movable body 4.

4 is a perspective view showing a composite body including a piezoelectric vibrator 1, a diaphragm 2 and a vibrating rod 3 in the ultrasonic actuator of FIG.

FIG. 5 is a plan view showing the piezoelectric vibrator 1.

FIG. 6 is a configuration diagram showing an embodiment of a self-excited oscillation drive circuit 5.

FIG. 7 is an admittance peak between terminals T _D and T _G in a composite of a piezoelectric vibrator 1, a diaphragm 2 and a vibrating rod 3,
The characteristic view which shows the relationship with the area ratio of the part D when the area of the part F is set to 1.

FIG. 8 is a characteristic diagram showing the relationship between the phase and frequency of admittance between terminals T _D and T _{G in the} piezoelectric vibrator 1 alone or in a composite body of the piezoelectric vibrator 1, the vibration plate 2, and the vibration rod 3.

FIG. 9 is a perspective view showing another embodiment of the composite body of FIG.

[Explanation of symbols]

1 Piezoelectric vibrator 2 Vibrating plate 3 Vibrating rod 4 Movable body 5 Self-excited oscillation drive circuit 6 Piezoelectric ceramic 7 Movable body 8 Movable body 9 Piezoelectric vibrator 10 Vibrating plate 11 Vibrating rod 12 Piezoelectric ceramic P Pendate electrode G electrode D, F Part T _D , T _F , T _G terminal V _dc DC power supply L ₁ coil T _r transistor R ₁ , R ₂ resistance D ₁ diode

Claims (11)

[Claims] 1. A piezoelectric vibrator, a vibrating plate fixed to the piezoelectric vibrator, at least one vibrating rod fixed to the vibrating plate, and a surface of the vibrating rod contacting or An ultrasonic actuator comprising a movable body that is brought into contact with a covering, the end of the vibrating rod being fixed to one plate surface of the vibrating plate, or a part of a side surface of the vibrating plate. The piezoelectric vibrator is fixed to a through hole penetrating the plate surface, and the piezoelectric vibrator includes a columnar piezoelectric ceramic and electrodes P and G, and the electrodes P and G are provided on both end surfaces perpendicular to the thickness direction of the piezoelectric ceramic. The vibrating plate is integrally fixed on the end face of the piezoelectric vibrator having the electrode P or G, and the electrode of the piezoelectric vibrator is directed toward the outside of the piezoelectric vibrator. Projected substantially parallel to the end face having P or G And, at least the electrode P among the electrodes P and G comprises a set of interdigital electrodes, said interdigital electrode portions D and F
The terminals _{D D} and T _F are respectively provided on the portions D and F of the interdigital electrode, the terminal T _G is provided on the electrode G, and the terminals T _D and T _G are By applying a voltage having a frequency substantially equal to the resonance frequency of the piezoelectric vibrator between the two, elastic vibration is excited in the piezoelectric vibrator, and the resonance frequency of the piezoelectric vibrator is the same as that of the piezoelectric vibrator. The elastic frequency is approximately equal to the resonance frequency of the complex composed of the vibrating plate and the vibrating rod, and the elastic vibration is propagated to the vibrating plate and converted into an electric signal between the terminals T _F and T _G to be output. An ultrasonic actuator, wherein a vibration displacement is generated on a surface of the vibration rod due to the elastic vibration transmitted to the vibration plate, and the vibration displacement moves the movable body. 2. The piezoelectric vibrator has a dimensional ratio of length to width of 1
A rectangular plate which is close to and not equal to 1, or a rectangular prism having a dimensional ratio of any two of length, width and thickness which is close to 1 and is not equal to 1. 1. The ultrasonic actuator according to 1. 3. The ultrasonic actuator according to claim 1, wherein the area of the portion D on one end face of the piezoelectric ceramic is approximately twice the area of the portion F. 4. The vibrating plate is integrally and integrally fixed to a portion of the end surface of the piezoelectric vibrator having the electrode G along the width direction of the piezoelectric vibrator, and the terminals T _D and T _F are fixed to each other. The ultrasonic actuator according to claim 1, wherein the ultrasonic actuator is provided in a portion along the width direction of the piezoelectric vibrator on an end surface of the piezoelectric vibrator having the electrode P. 5. An oscillating circuit comprising a transistor as an amplifying element and a composite element comprising the piezoelectric vibrator, the vibrating plate and the vibrating rod as a resonating element, wherein the oscillating circuit comprises a DC power supply V _dc and the terminal. A transistor for boosting connected to T _D , wherein the transistor has an output terminal of the transistor connected to the terminal T _D and an input terminal of the transistor connected to the terminal T _F , The ultrasonic actuator according to claim 1, 2, 3, or 4, wherein piezoelectric force appearing at the terminal T _F is received as a feedback voltage. 6. The ultrasonic actuator according to claim 1, wherein the vibrating rod has a linear shape, a curved shape, or a combination thereof. 7. The ultrasonic actuator according to claim 6, wherein the vibrating rod is branched into at least two. 8. The ultrasonic actuator according to claim 7, wherein the branched portion of the vibrating rod is branched into at least two. 9. The ultrasonic actuator according to claim 6, wherein the shape of the cross section of the vibrating rod perpendicular to the longitudinal direction is a square edge or an annular shape. 10. The movable body, which is brought into contact with the tip of the vibrating rod or a coating covering the tip, makes a rotary motion about the longitudinal direction of the vibrating rod.
The ultrasonic actuator according to 2, 3, 4, 5, 6, 7, 8 or 9. 11. The movable body, which is brought into contact with a side surface of the vibrating rod or a coating covering the side surface, moves or repeatedly moves along a length direction of the vibrating rod. , 3, 4, 5, 6, 7, 8 or 9, the ultrasonic actuator.