JPH08163880A - Ultrasonic oscillator and ultrasonic motor - Google Patents

Abstract

PURPOSE: To obtain an ultrasonic oscillator having simple structure using one type of piezoelectric element and a highly efficient miniature ultrasonic motor employing the ultrasonic oscillator. CONSTITUTION: Piezoelectric plates 12 are bonded to the side face and the back face of a resilient body. A silver stripe electrode 13 is formed on the piezoelectric plate 12 at an angle of 45 deg.. A rotor is pressed against a driver 14 bonded to the upper end part of the resilient body and secured in place.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic vibrator and an ultrasonic motor using the same.

[0002]

2. Description of the Related Art In recent years, ultrasonic motors have attracted attention as new motors to replace electromagnetic motors. This ultrasonic motor has the following advantages over conventional electromagnetic motors. (1) Low rotation and high torque can be obtained without gears. (2) Large holding power. (3) High resolution. (4) It is extremely quiet. (5) Magnetic noise is not generated and is not affected by noise.

As an invention of an ultrasonic motor having the above advantages, Japanese Patent Application Laid-Open No. 62-2 has been proposed by the present applicant.
There is an invention described in Japanese Patent No. 03570. The above invention is shown in FIG.
As shown in FIG. 2, the thickness sliding piezoelectric vibrator 1 is sandwiched between the U-shaped members 2. A pair of thickness longitudinal piezoelectric vibrators 3a and 3b are attached to both shoulders of the outer surface of the coupling end of the U-shaped member 2. And, this thickness longitudinal piezoelectric vibrator 3
A rotor 4 having a shaft is arranged in a pressed state so that one side surface can contact a and 3b.

In the ultrasonic motor having the above structure, first, a voltage having the same frequency as the natural frequency of the pendulum vibration (torsional vibration) of the U-shaped member 2 is applied to the thickness sliding piezoelectric vibrator 1 to cause torsional vibration. To excite. At the same time, a voltage of the same frequency is applied to the thickness vertical vibrators 3a and 3b to excite vertical vibration. When the torsional vibration and the longitudinal vibration are excited in synchronization with each other, the rotor 4 can be rotated. Further, when both vibrations are performed in opposite phases, the rotor 4 can be rotated in opposite directions.

[0005]

However, the invention described in JP-A-62-203570 has the following problems. That is, two types of piezoelectric vibrators, a sliding piezoelectric vibrator and a vertical piezoelectric vibrator, are required.
In addition, the configuration becomes complicated.

It is an object of the present invention to provide an ultrasonic vibrator having a simple structure by using only one type of piezoelectric element. An object of claim 2 is to provide a highly efficient ultrasonic motor using the ultrasonic vibrator of claim 1.

[0007]

According to a first aspect of the present invention, a prismatic elastic body and a rectangular piezoelectric element are joined to at least two or more of four side surfaces parallel to the longitudinal direction of the prismatic elastic body. An element plate and an annular driving element joined to the end face of the prismatic elastic body at right angles to the longitudinal direction. The piezoelectric element plates are formed in a plurality of strips at regular intervals, and the strips form a rectangle. A plurality of piezoelectric element plates, the electrodes having a certain acute angle with respect to the edge line segment, which are polarized by alternately applying positive and negative potentials and which are alternately connected in series. By applying an alternating voltage with a phase difference to each of them, longitudinal resonance vibration and torsion resonance vibration are excited at the same time,
The ultrasonic transducer is characterized in that ultrasonic elliptical vibration is excited at the position of the annular driver.

According to a second aspect of the present invention, a prismatic elastic body, a rectangular piezoelectric element plate bonded to at least two or more of four side surfaces of the prismatic elastic body which are parallel to the longitudinal direction, and It is composed of an annular driving element joined to an end surface of the prismatic elastic body at a right angle to the longitudinal direction, and a rotor pressed and installed on the annular driving element, and the plurality of piezoelectric element plates are formed in a band shape at regular intervals. In addition, the strip has electrodes that form a constant acute angle with respect to the line segment of the edge forming a rectangle, and the electrodes are polarized by alternately applying positive and negative potentials and are alternately connected in series. By applying an alternating voltage having a phase difference to each of the plurality of piezoelectric element plates, longitudinal resonance vibration and torsional resonance vibration are simultaneously excited, and ultrasonic elliptical vibration is excited at the position of the annular driver. Supersonic sound characterized by rotating the rotor It is a motor.

[0009]

According to the operation of claim 1, longitudinal resonance vibration can be excited by applying voltages of the same phase to the pair of piezoelectric element plates. In addition, torsional resonance vibration can be excited by applying piezoelectric materials of opposite phases to the pair of piezoelectric element plates. Furthermore, the phase of the pair of piezoelectric element plates is π
/ 2 When different voltages are applied, longitudinal resonance vibration and torsional resonance vibration are simultaneously excited, and ultrasonic elliptical vibration can be formed at the position of the annular driver.

According to the second aspect of the invention, when the rotor is pressed against the annular driving element in which the ultrasonic elliptical vibration is excited by the action of the first aspect, the rotor rotates clockwise or counterclockwise according to the vibration direction of the ultrasonic elliptical vibration. It is driven to rotate clockwise.

[0011]

Embodiment 1 FIGS. 1 to 8 show this embodiment, FIG. 1 is a front view of an ultrasonic transducer, FIG. 2 is a rear view thereof, and FIG. 3 is a plan view thereof.
4a and 4b are a front view and a side view of the piezoelectric element plate, FIG. 5 is a sectional view of an elastic body, FIG. 6 is a front view of an ultrasonic motor, FIG. 7 is a plan view thereof, and FIG. 8 is a sectional view thereof.

First, the structure of the ultrasonic transducer 10 will be described. FIG. 3 of the prismatic elastic body 11 made of stainless steel.
The piezoelectric element plates 12 are adhered to the respective surfaces of the surface (front surface) viewed from the direction α and the surface (back surface) viewed from the direction β. As shown in FIGS. 4A and 4B, the piezoelectric element plate 12 made of a piezoelectric ceramic material has a rectangular shape with a thickness of 0.3 mm, and a silver electrode 13 having a width of 3 mm and an angle of 45 degrees.
Are formed with a gap of 1 mm. Then, the silver electrode 13 is applied with positive and negative potentials in advance and is polarized as indicated by an arrow in the figure.

The piezoelectric element plate 12 as described above is adhered to the front surface and the back surface of the elastic body 11 using an epoxy adhesive. However, as shown in FIG. 2, the piezoelectric element plate 12 adhered to the back surface has a strip-shaped silver electrode 13 whose inclination is opposite. As shown in FIG. 1, the piezoelectric element plate 12 bonded to the front surface is wired for + and-, and the electric terminals A and GND are taken. As shown in FIG. 2, the piezoelectric element plate 12 adhered to the back surface is wired with + and −, and the electric terminals B and GN are connected.
D is taken. A driver 14 made of an annular grindstone material is joined to the upper end of the ultrasonic transducer 10. As shown in FIG. 5, a through hole 15 is provided in the central portion of the elastic body 11, and a tap is partially cut in the central portion of the through hole 15.

Next, the operation of the ultrasonic transducer 10 will be described. The dimensions of the ultrasonic transducer 10 are as follows: resonance longitudinal vibration of primary shape (vibration as indicated by arrow E in FIG. 1) and 1
The next resonance torsional vibration (vibration having the longitudinal vibration direction as the axis of torsion as shown by arrow F in FIG. 3) has almost the same frequency Fr.
It can be excited at (50 kHz to 56 kHz). In addition, there should be no natural vibration of bending resonance in the vicinity of this frequency.

First, the terminal A has an amplitude of 10 Vp at a frequency Fr.
When the alternating voltage of −p was applied and the alternating voltage of the same frequency and the same amplitude and the same phase was applied to the B terminal, the primary resonance longitudinal vibration could be excited. Next, at terminal A, the amplitude is 10 Vp at frequency Fr.
When an alternating voltage of −p was applied and an alternating voltage of the same frequency, same amplitude and opposite phase was applied to the B terminal, the first-order resonance torsional vibration could be excited. Next, at terminal A, frequency Fr and amplitude 10 V
When an alternating voltage of pp is applied and an alternating voltage having the same frequency and the same amplitude but different phase by 90 degrees is applied to the B terminal, the resonant longitudinal vibration and the resonant torsional vibration are combined, and at the position of the driver 14. Elliptical vibration was excited.

Next, the structure of the ultrasonic motor 20 will be described. A shaft 21 having a tap is inserted into the through hole 15 of the ultrasonic transducer 10 and is bonded and fixed at the central position of the ultrasonic transducer 10 as shown in FIG. An annular rotor 22 is pressed and fixed by a spring 23 on the upper end of the ultrasonic transducer 10. The pressing force on the driver 14 is adjusted by the nut 24. An annular rotor 22 has a sliding member 25 made of an annular zirconia ceramic bonded thereto, and a bearing 26 is press-fitted inside the sliding member 25. When the ultrasonic motor 20 is fixed, the shaft 21 protruding below the screw motor 21 is screwed and fixed to a base (not shown).

The action of the ultrasonic motor 20 is that the frequency Fr is applied to the A terminal and the B terminal of the ultrasonic transducer 10 as described above.
(Frequency between 50 kHz and 56 kHz), amplitude 10 V
An alternating voltage of pp and phase difference +90 degrees or -90 degrees is applied. Then, the rotor 22 rotates clockwise or counterclockwise.

According to this embodiment, a longitudinally twisted ultrasonic transducer can be constructed by using only one type of piezoelectric element plate. In addition, the simple structure facilitates cost reduction.
By using this ultrasonic oscillator, a small and highly efficient ultrasonic motor can be configured.

[0019]

Embodiment 2 FIGS. 9 to 11 show the present embodiment, FIG. 9 is a plan view of an ultrasonic transducer, FIG. 10 is a front view or right side view thereof, and FIG. 11 is a rear view or left side view thereof. is there.

The ultrasonic transducer 30 of this embodiment is provided with the piezoelectric elements 12 on all four side surfaces. Here, FIG. 10 is a view seen from the direction of α or γ in FIG. 9, and FIG. 11 is a view of β in FIG.
It is a view seen from the direction of δ. Regarding electrical wiring, A terminals are connected to each other to form an A phase, and B terminals are connected to form a B phase.

Since the action of the ultrasonic wave 30 is the same as that of the first embodiment, its explanation is omitted. In addition, the ultrasonic transducer 3 of the present embodiment
Since the configuration and operation of the ultrasonic motor using 0 are the same as those in the first embodiment, description thereof will be omitted.

According to the present embodiment, the number of piezoelectric element plates is doubled as compared with the first embodiment, so that the vibration amplitude of the ultrasonic transducer can be increased and the motor output can be increased.

[0023]

According to the effect of the first aspect of the present invention, a longitudinally twisted ultrasonic vibrator can be constructed by using only one kind of piezoelectric element plate. In addition, the simple structure facilitates cost reduction.
The effect of claim 2 is that by using the ultrasonic vibrator of claim 1, a small-sized and highly efficient ultrasonic motor can be configured.

[Brief description of drawings]

FIG. 1 is a front view showing a first embodiment.

FIG. 2 is a rear view showing the first embodiment.

FIG. 3 is a plan view showing the first embodiment.

4A and 4B are a front view and a side view showing the first embodiment.

FIG. 5 is a sectional view showing the first embodiment.

FIG. 6 is a front view showing the first embodiment.

FIG. 7 is a plan view showing the first embodiment.

FIG. 8 is a cross-sectional view showing the first embodiment.

FIG. 9 is a plan view showing a second embodiment.

FIG. 10 is a front view or a right side view showing the second embodiment.

FIG. 11 is a rear view or a left side view showing the second embodiment.

FIG. 12 is a perspective view showing a conventional example.

[Explanation of symbols]

 10 Ultrasonic vibrator 11 Elastic body 12 Piezoelectric element 13 Silver electrode 14 Driver 20 Ultrasonic motor 21 Shaft 22 Rotor 23 Spring 24 Nut 25 Sliding material 26 Bearing

Claims (2)

[Claims] 1. A prismatic elastic body, a rectangular piezoelectric element plate bonded to at least two or more of four side surfaces parallel to the longitudinal direction of the prismatic elastic body, and a longitudinal direction of the prismatic elastic body. A plurality of piezoelectric element plates are formed in a band shape at a constant interval, and the piezoelectric element plates are formed at a constant acute angle with respect to a line segment of an edge forming a rectangle. The electrodes are polarized by applying positive and negative potentials alternately and are alternately connected in series, and an alternating voltage with a phase difference is applied to each of the plurality of piezoelectric element plates. An ultrasonic transducer characterized by exciting longitudinal resonance vibration and torsional resonance vibration at the same time by applying, and exciting ultrasonic elliptical vibration at the position of the annular driver. 2. A prismatic elastic body, a rectangular piezoelectric element plate bonded to at least two or more of four side surfaces of the prismatic elastic body which are parallel to the longitudinal direction of the prismatic elastic body, and the prismatic elastic body. An annular drive element joined to an end surface perpendicular to the longitudinal direction, and a rotor pressed and installed on the annular drive element, and the piezoelectric element plates are formed in a plurality of strips at regular intervals,
The strip has electrodes that make a constant acute angle with respect to the line segments of the edges that form the rectangle; the electrodes are polarized by alternately applying positive and negative potentials and are alternately connected in series; By applying an alternating voltage having a phase difference to each of the plurality of piezoelectric element plates, longitudinal resonance vibration and torsional resonance vibration are simultaneously excited, and ultrasonic elliptical vibration is excited at the position of the annular driver. An ultrasonic motor characterized by rotating the rotor.