JPH0513401B2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field The present invention is directed to electric strain change in the longitudinal direction (length vibration).
This invention relates to a different direction bibending vibrator that converts vibration into mechanical vibration in the thickness direction.

Prior Art Piezoelectric bimorphs, which are made by bonding a metal plate to piezoelectric ceramics, are known as devices that utilize the characteristic of piezoelectric ceramics to vibrate in length when a voltage is applied and convert the length vibrations into mechanical vibrations in the thickness direction. There is.

In addition, by bonding two piezoelectric ceramics so that the expansion and contraction directions are opposite when a voltage is applied, and causing one side to stretch and the other to contract alternately, this can also be converted into mechanical vibration in the thickness direction. Is possible.

In any case, in the production of piezoelectric ceramics, it is essential to apply a high voltage to ferroelectric ceramics that have spontaneous polarization to fix the polarization direction in one direction, so-called polarization treatment (poling treatment). Only single polarization treatment, ie, polarization treatment in one direction for one ceramic piece, is always considered.

Problems to be Solved by the Invention The piezoelectric ceramic described above has a single polarization structure, and the vibration motion in the thickness direction when a voltage is applied is a simple bending motion.

Therefore, the use of the piezoelectric ceramic is limited to applications where bending motion is used as a vibration source, such as electroacoustic exchangers and piezoelectric filters.

As described above, conventional piezoelectric ceramic vibrators are basically limited to vibration modes such as thickness direction vibration due to simple bending motion, length vibration, or radial direction vibration. The piezoelectric ceramic is made to have birefringence in different directions, and the piezoelectric ceramic partially bends in one direction in the thickness direction while simultaneously partially bending in the other direction in the thickness direction, which has a unique vibration mode that causes so-called torsional vibration. It is an object of the present invention to provide a directionally bibending resonator.

This has expanded the use of piezoelectric ceramics to new fields that make use of the above torsional vibration mode, which had not been previously envisioned, and made it possible to put it into practical use as a detection vibrator for viscosity detection elements, for example. be.

Means for solving the problem: The two diagonal quadrants of a rectangular piezoelectric ceramic are polarized in the thickness direction and in the positive direction, and the other two diagonal quadrants are polarized in the thickness direction. and a negative direction polarization region, and the multi-polarized piezoelectric ceramics having the above configuration are bonded together so that each polarization region faces each quadrant, and the length of each opposing polarization region in each quadrant when a voltage is applied is determined. This is a different direction bibending type vibrator having a counter electrode structure in which the vibration directions are opposite to each other.

Effect According to the present invention, when the vibration mode of the bipolarized piezoelectric ceramic is compressed in the positive polarization region in one of the two diagonal quadrants, the vibration mode shrinks in the negative polarization region in the other diagonal quadrant. When elongation occurs, and conversely, when elongation occurs in the positive polarization region in two diagonal quadrants, contraction occurs in the negative polarization region in the other diagonal two quadrants, and in each divided polarization region. A combination of stretching vibration modes in opposite directions occurs. Therefore, when these multi-polarized piezoelectric ceramics are bonded to each other in the opposite polarity structure as described above, one set of opposing polarized regions will elongate and the other will contract, and the other set of polarized regions will expand. In this case, shrinkage occurs on one side, and elongation occurs on the other side, and the former bends in one direction in the thickness direction, and the latter bends in the other direction in the thickness direction. By causing this operation alternately in each of the opposing polarization regions in each quadrant, so-called double bending vibration, that is, good torsional vibration is induced.

Example Embodiments of the present invention will be described below based on the drawings.

As mentioned above, piezoelectricity is imparted to piezoelectric ceramic by subjecting ferroelectric ceramic to polarization treatment (poling treatment).

The polarization process is a process of fixing the polarization direction in one direction as described above, and depending on the polarization direction, the elongation or contraction direction (length vibration direction) with respect to a positive voltage or a negative voltage becomes opposite. In order to distinguish between the polarization directions exhibiting these different vibration modes, the piezoelectric ceramic is polarized in the drawing so that it has a (+) poling electrode on one surface and a (-) poling electrode on the other surface in the positive direction. This is called a polarized region, and conversely, a region that is polarized so that it has a (+) poling electrode on the other surface side and a (-) poling electrode on one surface side of the piezoelectric ceramic is called a negative direction polarization region.

In the present invention, the piezoelectric ceramic forming the bonded body is divided into the positive direction polarization region and the negative direction polarization region. As shown in FIG. 1, a single piezoelectric ceramic 1 is subjected to a poling process into a plurality of polarization regions having different polarization directions.
Divided into positive and negative polarization regions.

In addition, as shown in Fig. 9, etc., as another classification mode,
A polarization pattern is formed by assembling a plurality of pieces of piezoelectric ceramic 1, ie, a positively polarized ceramic piece and a negatively polarized ceramic piece, on a plane.

As a suitable example of the polarization pattern in each of the above examples, as shown in each figure, a rectangular piezoelectric ceramic 1 is divided into four quadrants. In this polarization process, positive direction polarization regions P2 and P3 are formed in two diagonal quadrants, and negative direction polarization regions P1 and P4 are formed in the other two diagonal quadrants. On the opposing surfaces of the bipolarized piezoelectric ceramic 1, there are electrodes 3, 4 for applying a driving voltage that cover the entire polarized region.
is applied.

As shown in FIGS. 1 to 7, the piezoelectric ceramic 1 having a rectangular outer shape as described above is divided into four quadrant polarization regions, and two quadrants occupying one diagonal corner have positive direction polarization regions. Negative direction polarization regions P1 and P4 are respectively arranged in two quadrants occupying the other diagonal corners, P2 and P3 are arranged, and a mutually bonded body of the four-polarized piezoelectric ceramic 1 is formed, and each of the four-polarized piezoelectric The polarized regions P1 to P4 of the ceramics 1A and 1B are opposed to each other so that the directions of length vibration when voltage is applied are opposite to each other.

That is, in the case of parallel connection, as shown in FIG. 5, the positive direction polarization regions P2 and P3 of the two quarter-polarized piezoelectric ceramics 1A and 1B are made to face each other,
In addition, the negative direction polarization regions P1 and P4 are made to face each other and bonded together so that the voltage application directions are opposite to each other.

In addition, in the case of series connection, as shown in FIGS. 6 and 7, two quadrupolarized piezoelectric ceramics 1A and 1B are connected with one positive direction polarization region P2, P3 and the other negative direction polarization region P1, P4. facing each other, one negative direction polarization region P1, P4 and the other positive direction polarization region P
2 and P3 are made to face each other and bonded together so that the polarization directions are opposite to each other.

When the four-polarized piezoelectric ceramics 1A and 1B are bonded together according to the above convention, one pair of polarized regions facing each other will elongate, the other will contract, and the other pair of polarized regions will have one side. In this case, shrinkage occurs, and in the other case, elongation occurs; the former bends in one direction in the thickness direction, and the latter bends in the other direction in the thickness direction. In this way, double bending vibrations, ie torsional vibrations, are also induced.

That is, as shown in FIGS. 8 and 9, for example, in a pair of positive direction polarization regions P2 and P3, when one of the four-polarized piezoelectric ceramics 1A extends x1, the other four-polarized piezoelectric ceramic 1B contracts. x2, and therefore the pair of positive polarization regions P2, P3 is bent y1 in one direction in the thickness direction.

On the other hand, in the other set of negative direction polarization regions P1 and P4, one of the four-polarized piezoelectric ceramics 1A shrinks.
When x2 occurs, the other four-polarized piezoelectric ceramic 1B
causes an elongation x1, and therefore the pair of negatively polarized regions P1 and P4 bends y2 in the other direction in the thickness direction.

Further, FIGS. 10 and 11 show the case where the above-mentioned split or non-split type bipolarized piezoelectric ceramic 1 is bonded to both sides of the diaphragm 2 as a medium to form the above-mentioned torsional vibrator.

As described above, by repeating the movement in which the two sets of polarized regions alternately bend in opposite directions, biflex vibration in the thickness direction, that is, torsional vibration is induced.

As shown in FIG. 12, the unit multi-polarized piezoelectric ceramic 1 of each of the above-mentioned embodiments is made of multi-layered multi-polarized piezoelectric ceramics having the same segmented pattern, and two or more units of this are bonded together to produce the above-mentioned different direction biflex vibration. May form offspring.

Further, in the above embodiment, the piezoelectric ceramic is subjected to quadrupolarization treatment, but according to the embodiment, a plurality of units of quadrupolarization regions are arranged side by side in a band shape, and the above-mentioned torsional vibration is continuously performed. .

Effects of the Invention According to the present invention, when each bipolarized piezoelectric ceramic contracts in a positive polarization region in two diagonal quadrants, it expands in a negative polarization region in the other two diagonal quadrants. conversely, when elongation occurs in the positive polarization region in two diagonal quadrants, contraction occurs in the negative polarization region in the other diagonal two quadrants, and opposite polarization occurs in each divided polarization region. A combination of directional stretching and contraction vibration modes is generated. Therefore, this multi-polarized piezoelectric ceramic was bonded together in an opposite polar structure in which the polarized regions of each quadrant faced each other, and the length vibration directions of the opposing polarized regions were opposite to each other. In each pair of opposing polarized regions existing in two quadrants, elongation occurs in two quadrants of one piezoelectric ceramic, and contraction occurs in two quadrants of the other piezoelectric ceramic, resulting in a combination of elongation and contraction in one direction in the thickness direction. In addition, in the other set of polarized regions existing in the other two diagonal quadrants, contraction occurs in two quadrants of one piezoelectric ceramic and expansion occurs in two quadrants of the other piezoelectric ceramic. By encouraging bending in the other direction in the thickness direction and inducing this action alternately in each opposing polarized region in each quadrant,
Active and efficient torsional vibration can be induced.

This will expand the use of piezoelectric ceramics to new fields that utilize the above-mentioned torsional vibration mode, which had not been previously envisioned, and will lead to the development of new industrial uses, such as detection vibrators such as viscosity detection elements. This made it possible.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of an embodiment of the bidirectionally polarized piezoelectric ceramic according to the present invention formed by bonding two bipolarized piezoelectric ceramics together, FIG. 2 is a perspective view of the bonded body, and FIG. 2 is a cross-sectional view taken along the line A-A in FIG. 2, FIG. 4 is a cross-sectional view taken along the line B-B, FIG. 5 is a side view showing an example of parallel connection of the same bonded body, and FIG. FIG. 7 is an exploded perspective view showing another example of opposing polarized regions in the bonded body, FIG. 7 is a side view showing an example of series connection of the bonded body, and FIG.
The figure is a perspective view illustrating torsional vibration in the above-mentioned bonded body, FIGS.
Fig. 1 is a perspective view showing an example of an embodiment in which a non-split type and a split type multi-polarized piezoelectric ceramic are bonded together using a diaphragm as a medium, and Fig. 12 is a perspective view showing an embodiment of the multi-polarized piezoelectric ceramic in each of the above embodiments. FIG. 2 is an exploded perspective view showing an embodiment example having a layered structure. 1...Dipolarized piezoelectric ceramic, 2...Vibration plate,
3, 4...electrode, P1, P4...negative direction polarization region, P2, P3...positive direction polarization region.

Claims (1)

[Claims] 1. Divide a rectangular piezoelectric ceramic into four quadrant polarization regions, and make the two diagonal quadrants polarized in the thickness direction and in the positive direction, and the other two diagonal quadrants polarized in the thickness direction. The multi-polarized piezoelectric ceramics having the above configuration are bonded together so that each polarized region faces each other in each quadrant, and each opposing polarized region in each quadrant is polarized in a negative direction. What is claimed is: 1. A different direction bibending type vibrator characterized by having an opposite electrode structure in which the longitudinal vibration directions of the two are opposite to each other.