JPS5989583A - Driving device using piezoelectric vibrator - Google Patents

Abstract

PURPOSE:To effectively utilize a piezoelectric vibrator which solely vibrates by providing an electrode lacking part so as to partly suppress the vibration displacing amount of a cantilever piezoelectric vibrator in the lengthwise direction and differentiating the areas of the electrodes from each other. CONSTITUTION:A rectangular piezoelectric vibrator 3 is supported by a cantilever beam, and electrodes 1, 2 are formed at both side surfaces. An electrode lacking part 4 is formed at the electrode 1, and the area of the electrode 1 is reduced to be smaller than that of the electrode 2. The electrodes 1, 2 of the vibrator 3 are connected to AC voltage applying means 7, and a rotor 5 is rotated in a displacement based on the vibrating trace of the vibrator 3.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive device using vibration of a piezoelectric vibrator as a drive source.

The purpose of the present invention is to create a piezoelectric vibrator (particularly as shown in FIG. 3), and is supported by a so-called cantilever beam that can be fixed only on the right side in the figure. 1st
Although the structure shown in the figure is used, an electrode missing part (4) is provided and the electrode (
The area of electrode (1) is set smaller than that of electrode (2).

However, in this example, the area of the electrode (1) is made small, but this is not a condition that is restricted by the polarization direction, and the electrode (2) side may be made small. The purpose is to bring about the contact state in the detailed embodiment.

The so-called piezoelectric effect, in which a polarized piezoelectric vibrator vibrates with a strain proportional to the electric field, is well known, but in Figure 2, when an electric field is applied to electrodes (I) and (2), The electric field distribution inside the piezoelectric vibrator (3) becomes as shown in the shaded area in FIG. 2, where the distribution is suppressed near the electrode missing part (4) where the electrode is missing.

Therefore, the single vibration in the length direction of the piezoelectric vibrator (3) is also partially suppressed near the electrode cutout (4), and the vibration on the side opposite to the fixed end side of the piezoelectric vibrator (3) in the figure is suppressed. Examples of various drive devices using the piezoelectric vibrators described above will be described below.

However, in the following embodiments, AC voltage is applied to the piezoelectric vibrator to drive it, and although it varies somewhat depending on the shape of the vibration axis or polarization direction of the piezoelectric vibrator, in general, the It is well known that the oscillator has a resonant frequency that resonates with the elastic natural vibration of By varying the AC frequency, no particular explanation will be given.

(g) First embodiment In this embodiment, the rotor (5) in Fig. 3 is replaced with the shaft (6).
It is a drive device that rotates around the .

Electrodes (1), (
2) is connected to the AC voltage applying means (7) and turned on when desired.
, and the disc-shaped rotor (5) is rotatably mounted on a shaft (6).

In order to rotate the rotor (5), the piezoelectric vibrator (3) is brought into contact with the outer circumferential surface (curved surface) of the rotor (5) in this embodiment to constitute a thin drive device.

In addition, as shown in the figure, the corresponding contact is an electrode with a large area (2
The free end of the piezoelectric vibrator (3), which has one end fixed, is brought to the outer circumferential surface of the rotor (5) with its free end lower side in the figure facing the outer circumferential surface of the rotor (5).

In this state, when the AC voltage applying means (force) is turned on, the piezoelectric vibrator (3) vibrates, but the vibration is only a simple vibration because the amount of vibration displacement is microscopically unbalanced in the thickness direction as shown in Figure 2. It is not a reciprocating linear motion, but after coming into contact with the outer peripheral surface of the rotor (5), it moves to the side away from the rotor (5) in Figure 3, and as a result, the trajectory of the vibration displacement of the free end is not shown in the figure. It becomes a pseudo-ellipse as shown in FIG.
rotates in the direction shown.

If the piezoelectric vibrator simply vibrates in a single manner, the rotor will not rotate no matter what state it contacts, especially if the contact surface is a curved surface as in the configuration of this example. It has been revealed through experiments by the present inventor that a stable driving force can be obtained by configuring the structure so that the ) is a drive device for linear movement.

Although this embodiment can be applied not only to plate-shaped bodies but also to rod-shaped bodies, the electrodes (1) and (2) of the cantilever piezoelectric vibrator (3) shown in FIG. (7) connected to
As shown in the figure, the piezoelectric vibrator (3) is in contact with the piezoelectric vibrator (3) with one end fixed so that the large-area electrode (2) side faces the plate-shaped body (8). The lower side of the free end in the figure is brought to the surface of the plate-shaped body (8).

When the AC voltage applying means (7) is turned on from the above state, the locus of the free end vibration displacement becomes an ellipse as described above, and the plate-shaped body (8) is therefore driven in the direction shown.

If the vibrator is a simple reciprocating linear motion, the drive stroke displacement amount of the plate-shaped body (8) corresponding to the vibration will be uniquely determined by the contact angle of the vibrator, but according to this embodiment, the vibration Since the locus of displacement also depends on the area of the electrode cutout (4), by varying the area of the electrode cutout (4), the drive stroke displacement amount of the plate-shaped body (8) can be maintained at the same contact angle. The degree of freedom of the contact angle of the piezoelectric vibrator is improved.

Regarding the structure of the piezoelectric vibrator (3) in the above embodiment, it is better to form a multilayer structure by laminating a large number of thin diaphragms.
The theoretical efficiency is good, and in this case, the electric field distribution can be set to the desired intensity by varying the electrode area, and the benefits of the present invention can be obtained. Even if a wear-resistant member (9) is provided by baking or bonding to improve wear resistance as shown in Fig. 5, the present invention does not apply to a device that obtains driving force by utilizing vibration displacement caused by a difference in electrode area. It encompasses.

As described above, in the drive device using the piezoelectric vibrator of the present invention, an electrode cutout is provided in order to partially suppress the amount of vibrational displacement in the longitudinal direction of the cantilever piezoelectric vibrator at the free end. The piezoelectric vibrator has different electrode areas, and when the free ends are mechanically related and abutted, the vibration displacement of the piezoelectric vibrator is used to obtain a driving force, thereby providing a drive device with a simple structure. It is suitable for this purpose and has great practical value.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram for explaining a conventional piezoelectric vibrator, Fig. 2 is a schematic diagram for explaining a piezoelectric vibrator used in an embodiment of the present invention, and Fig. 3 is a schematic diagram for explaining a piezoelectric vibrator used in an embodiment of the present invention. FIG. 4 is a schematic diagram of a driving device in a second embodiment, and FIG. 5 is a schematic diagram for explaining a piezoelectric vibrator of another embodiment. Explanation of symbols (1), (2)... Electrode (
3)... Piezoelectric vibrator (4)... Electrode missing part (5)... Rotor (force...
・・・・・・AC voltage application means (8)・・・Plate body patent applicant Aiwa Co., Ltd. / h-5 Figure 9 54

Claims (1)

[Claims] In order to partially suppress the amount of vibrational displacement in the longitudinal direction of the cantilever piezoelectric vibrator at the free end, an electrode cutout is provided to make the mutual electrode areas different, and the free ends are mechanically related to each other. A drive device using a piezoelectric vibrator, characterized in that a driving force is obtained by the vibration displacement of the piezoelectric vibrator when the piezoelectric vibrator is brought into contact with the piezoelectric vibrator.