JPH0284076A - Vibrator type actuator - Google Patents

Abstract

PURPOSE:To obtain a vibrator type actuator in simple structure, easy to miniaturize, inexpensive to manufacture, of which the piezoelectric vibrator is rectangular-solid-shaped, by constituting a piezoelectric vibrator by a ceramic piezoelectric body moulded in a rectangular solid and a pair of electrodes secured to two end faces mutually parallel on this piezoelectric body. CONSTITUTION:This actuator is composed of a piezoelectric vibrator 1, a rotor 2 and a pressure welding means to press the rotor 2 to the piezoelectric vibrator 1. The piezoelectric vibrator 1 is composed of a ceramic piezoelectric body 11 and electrodes 12, 13a and 13b. A rotating shaft 21 is provided to the rotor 2. The electrodes 13a and 13b are mutually insulated. Among a pair of electrodes an electrode is divided into 13a and 13b. The shape of the piezoelectric body 11 is a cube with one side 5mm. The moving direction of a moving piece can be changed at will only by switching over the electrode to which voltage is applied in single phase AC for exciting piezoelectric vibrator.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an actuator suitable for use in transferring cards such as bank cards in a machine that reads the cards, and in particular to an actuator suitable for use as an electric NWA conversion element. @Relates to a vibrator type actuator using a vibrator.

(Prior Art and Problems) Ultrasonic motors are well known among vibrator-type actuators that use piezoelectric vibrators as electromechanical conversion means for converting electrical energy into mechanical energy. Ultrasonic motors have a lower rotational distance and larger torque than electromagnetic motors that rotate using electromagnetic force, so they have a wide range of uses as actuators for precision machinery. However, conventionally known ultrasonic motors are The mechanical structure of the piezoelectric vibrator and the electrical circuit that vibrates the piezoelectric vibrator are complex, making it difficult to downsize and expensive.

As a vibrator-type actuator that can be easily miniaturized and manufactured at low cost, there is a ``Vibrator-type actuator'' (Japanese Patent Application 1983-1983), which was invented and patented by the same person as the inventor of the present application.
129122, 63-157506), and the piezoelectric vibrators used in the vibrator type actuators of these existing applications are cylindrical, but depending on the application, a rectangular piezoelectric vibrator may be easier and more convenient to mount. many.

The ultrasonic motors that have piezoelectric vibrators in a rectangular shape (square plate shape or prismatic column shape) and that have been announced to date include the following.

■ Isomorphic degenerate in-plane bending vibration mode of a square plate (
``Ultrasonic motor using multi-mode transducer of in-plane vibration'', U 387-32 (198
7) ).

■ Two vertical vibrations (B
(ending-bending mode) that obtains an elliptical motion (commonly used fl!! = "Ultrasonic motor configuration and its application", U
587-5 (1987)).

No characterization results have been reported for these two types.

■ A strip-shaped electrode is formed on a single prism (square rod) of piezoelectric ceramic, and the electrode performs polarization and excitation, making it a homogeneous degenerate type 2N! Ultrasonic linear motor using a modulated bending vibrator (each day, Shimizu 2 "Piezoelectric Ceramic Acoustic Piece Type Ultrasonic Linear Motor", Onko Ronshuu, 82.10).

For elliptical motion drive: input 141 V, 0.89 W,
When f = 21.7kHz, maximum speed 16C1/S - maximum thrust 60gw For linear motion drive: input 283V, 0.931
4. When f = 22.3kHz, maximum speed is 7.6cm/S, maximum thrust cuff is 5gw. Figure 4 is a diagram explaining the ultrasonic motor mentioned in (■) above, and Figure (a) shows how the pressure of the transducer is A perspective view, (b) is a conceptual diagram showing the directions of polarization and excitation in a piezoelectric vibrator, (7)
c+ is a conceptual diagram showing the vibration mode in the piezoelectric vibrator, and FIGS. 10(d) and 1(e) are a plan view and a side view of the ultrasonic motor, respectively.

However, in the ultrasonic motors (1) to (2) above, the mechanical structure of the piezoelectric vibrator and the electric circuit that excites the piezoelectric vibrator are complicated, and there are problems with miniaturization and price.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a vibrator type actuator that has a simple structure, can be easily miniaturized, can be manufactured at low cost, and has a piezoelectric vibrator in the shape of a rectangular parallelepiped.

(Means for Solving the Problems) Means provided by the present invention to solve the above-mentioned problems are as follows:
A vibrator-type actuator comprising a piezoelectric vibrator and a moving element, and displacing the moving element by vibrational displacement generated in the piezoelectric vibrator when an alternating current voltage is applied to the piezoelectric vibrator, the piezoelectric vibrator is a ceramic piezoelectric body formed into a rectangular parallelepiped, and a pair of ! The movable element is in contact with a side surface perpendicular to the end surface of the piezoelectric vibrator, and one of the pair of @poles is composed of an electrode A and an electrode B that are electrically insulated from each other. It is characterized by

(Example) Next, the present invention will be explained in detail with reference to Examples.

FIG. 1 is a perspective view showing an embodiment of the present invention.

This embodiment consists of a piezoelectric vibrator 1, a rotor 2, and pressure contact means (not shown) for pressing the rotor 2 against the piezoelectric vibrator 1, and the piezoelectric vibrator 1 includes a ceramic piezoelectric body 11, The rotor 2 is provided with a rotating shaft 21. Electrode 1
3a and 13b are insulated from each other.

In this example, one of the pair of electrodes is 13
It is divided into a and 13b. The shape of the piezoelectric body 11 is a cube with one side of 5 mm. Let Young's modulus be Y is” (
N/m'), the density is ρ (kg/m'), and Poisson's ratio is σ, then the material constant of the piezoelectric body 11 is Yss'=7.
7X10" p=7.6 x10', a=o.

It is 28. The polarization axis of the body 11 is the electrode 12.13a,
13b.

FIG. 2 shows the vibration displacement generated on the surface of the piezoelectric body 11 of the embodiment shown in FIG. 1 when an AC voltage with a frequency f of 233.2 kHz is applied between the electrodes 12 and 13a of the embodiment shown in FIG. It is a conceptual diagram shown in FIG. Vibratory displacements in the direction of the X and Z axes occur in the opposite direction to that in FIG. 2 when an alternating voltage is applied between the electrodes 12 and 131).

However, the vibration displacement in the Y-axis direction is determined by changing the voltage applied electrode to 13
Even if the direction is changed from a to 13b, the direction is the same as in FIG.

FIG. 3 shows the piezoelectric vibrator 1 in the embodiment shown in FIG.
When applying an AC voltage of ~600kHz, the pressure @
As is clear from the graph showing the frequency characteristic of admittance shown by the vibrator, this piezoelectric vibrator 1 has a frequency of f+
, f, , fs, and large vibrational displacements appear at these frequencies. The fl is 233
．． 2 kHz, and when the piezoelectric vibrator 1 is excited at this frequency, a vibrational displacement occurs as indicated by the arrow in FIG. 2, as described above.

The embodiment shown in FIG. 1 is an actuator that extracts the vibrational displacement shown in FIG. 2 as rotational force, and the rotor 2 rotates around a rotating shaft 21 in the direction of the arrow in FIG.

Of course, the rotation of the rotor 2 depends on the excitation AC voltage rj
By switching the application from h-pole 13a to 13b, it is possible to change the direction opposite to the arrow in FIG. 1.

Although FIG. 1 does not show a means for stably contacting the rotor 2 with the piezoelectric body 11, for example, it is sufficient to press the bearing of the rotating shaft 21 in the direction of the piezoelectric body 11 with a spring. Therefore, detailed explanation will be omitted.

By adopting the structure in which the rotor 2 of the embodiment shown in FIG. 1 is brought into contact with the card, this embodiment can be used in automatic cash withdrawal machines of banks, etc. Note that a hard material such as hard plastic or metal is suitable for the rotor 2, and if it touches the card directly, it may damage the card.

In order to eliminate such a fear, a second rotor made of rubber or the like is provided, and the rotation of the rotor 2 is transmitted to the second rotor.
The second rotor may be brought into contact with the card.

In the first embodiment, the excitation AC voltage remains single-phase, and the applied Wb f! Since the rotational direction of the rotor 2 can be arbitrarily changed by simply switching between 13a and 13b, the excitation circuit for the piezoelectric vibrator is simple.

(Effects of the Invention) As described above in detail with reference to examples, in the present invention, the shape of the piezoelectric vibrator is a rectangular parallelepiped, which makes it easy to mount in equipment, and the structure is simple. The actuator of the present invention can therefore be manufactured at low cost. Also,
The moving direction of the mover is pressure t fii! The configuration of the piezoelectric vibrator excitation circuit can be simplified because it can be arbitrarily changed by simply switching the voltage application f4 pole in the single-phase alternating current for IJ element 11ilJ vibration.

3 is a characteristic diagram showing the frequency-admittance relationship of the piezoelectric vibrator 1 in the embodiment of FIG. 1, and FIG. 4 is a type of conventional vibrator type actuator. It is a figure explaining an ultrasonic motor.

DESCRIPTION OF SYMBOLS 1... Piezoelectric vibrator, 2... Rotor, 11... Ceramic piezoelectric body, 12.13a, 13b... Electrode, 21
...Rotor's rotation axis.

Claims (2)

[Claims] 1. A vibrator-type actuator comprising a piezoelectric vibrator and a moving element, and displacing the moving element by vibrational displacement generated in the piezoelectric vibrator when an alternating current voltage is applied to the piezoelectric vibrator, wherein the piezoelectric vibrator comprises: It consists of a ceramic piezoelectric body shaped into a rectangular rectangular shape and a pair of electrodes fixed to two mutually parallel end faces of the piezoelectric body. A vibrator-type actuator comprising an electrode A and an electrode B, one of the pair of electrodes being electrically insulated from each other. 2. Claim 1, further comprising means for pressing the side surface of the piezoelectric vibrator and the moving element into pressure contact with each other.
The vibrator type actuator described.