JPH0429280B2 - - 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 torsional oscillator that converts vibration into mechanical vibration in the thickness direction.

Conventional technology A vibrator (piezoelectric bimorph) made by bonding a metal plate to a piezoelectric ceramic is used to convert the length vibration into mechanical vibration in the thickness direction by utilizing the characteristic of piezoelectric ceramic that vibrates in length when a voltage is applied. It has been known. In addition, two pieces of piezoelectric ceramic are pasted together so that the directions of expansion and contraction are opposite when a voltage is applied, and by alternately causing expansion and contraction on one side and contraction on the other side, vibration is converted into mechanical vibration in the thickness direction. Child is provided.

The piezoelectric ceramic described above is a ferroelectric ceramic having spontaneous polarization which is subjected to a so-called polarization treatment (poling treatment) in which a high voltage is applied to fix the polarization direction in one direction.

Problems to be Solved by the Invention In all of the piezoelectric ceramic vibrators described above, the vibration motion in the thickness direction when voltage is applied is a simple bending motion.

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

As mentioned above, conventional piezoelectric ceramics are basically limited to vibration modes such as length vibration, thickness direction vibration, or radial vibration using the bending motion source as described above. The invention provides a unique vibration mode in which the piezoelectric ceramic has birefringence in different directions, and the piezoelectric ceramic partially bends in one direction in the thickness direction and at the same time partially bends in the other direction in the thickness direction, causing so-called torsional vibration. It is an object of the present invention to provide a torsional oscillator having the following characteristics and which can be suitably used industrially.

Through this, we aim to expand the use of piezoelectric ceramics to new fields that utilize the above-mentioned torsional vibration mode, and provide products that are highly suitable as detection oscillators, such as viscosity detection elements or hydrometers. .

Means for Solving the Problems As a means for solving the above problems, the present invention provides a vibrator in which a diaphragm is interposed between longitudinally vibrating piezoelectric elements and laminated, one side of the diaphragm and the other. The two-length vibrating piezoelectric elements on the surface side are arranged so that their length vibration directions intersect, and the two-length vibrating piezoelectric elements are lengthened so that they simultaneously expand or contract on one side and the other side of the diaphragm. By causing the diaphragm to vibrate, torsional vibration of the diaphragm is obtained.

Effects According to the present invention, when the vibration modes of the above-mentioned crossing piezoelectric elements cause contraction in one crossing piezoelectric element, contraction occurs in the other crossing piezoelectric element at the same time, and conversely, an extension occurs in one crossing piezoelectric element. At the same time, the other piezoelectric element elongates, and a plurality of elongation and contraction vibration modes in the same direction occur in each piezoelectric element. Therefore, the diaphragm bonded to this is bent in one direction in the thickness direction at both ends of the vibrating piezoelectric element of one length that intersects, and at the same time bends in the thickness direction at both ends of the vibrating piezoelectric element of the other length that intersects. It will be bent. By causing this alternately, so-called double bending vibration (torsional vibration) is induced.

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

As the piezoelectric element, a piezoelectric ceramic is used, which is obtained by subjecting ferroelectric ceramic to polarization treatment (poling treatment) to impart piezoelectricity as described above. The polarization process is a process in which the polarization direction is fixed in one direction, 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.

As shown in FIGS. 1 to 11, the present invention is a vibrator in which a diaphragm 3 is interposed and laminated between piezoelectric ceramics 1 and 2 that vibrate along the length, and one side of the diaphragm 3 is The vibrating piezoelectric ceramics 1 and 2 with both lengths on the other side are arranged so that their length vibration directions intersect, and the vibrating piezoelectric ceramics 1 and 2 with both lengths are connected to the diaphragm 3.
The diaphragm 3 is vibrated in length so as to cause expansion or contraction simultaneously on one side and the other side, thereby obtaining torsional vibration of the diaphragm 3.

To explain this specifically, as shown in FIGS. 1 to 3 (first embodiment), a pair of elongated piezoelectric ceramics 1 and 2 each having a rectangular shape that vibrates in the longitudinal direction is prepared, and one An elongated piezoelectric ceramic 1 is attached to one side of a rectangular diaphragm 3, and the other elongated piezoelectric ceramic 2 is attached to the other side of the diaphragm 3. and the other elongated piezoelectric ceramic 2 is arranged on the other diagonal of the diaphragm 3 so that the longitudinal vibration directions of both elongated piezoelectric ceramics 2 intersect. Each piezoelectric ceramic 1, 2
intersect at the center of the rectangular diaphragm 3, and both ends thereof are located at diagonal corner portions of the diaphragm 3.

In the case of parallel connection as shown in FIG. 4A, both elongated piezoelectric ceramics 1 and 2 are bonded to one side and the other side of the diaphragm 3 so that their respective polarization directions P are opposite to each other. Form a crossover state.

Also, as shown in Figure 4B, in the case of series connection,
The elongated piezoelectric ceramics 1 and 2 are stacked on the diaphragm 3 in the above-mentioned crossed arrangement so that the polarization directions are the same.

The piezoelectric ceramics 1 and 2 shown above have a single-layer structure, but as explained above, a plurality of ceramic bimorphs that utilize the characteristic of piezoelectric ceramics to vibrate along their length are used to generate bending motion. You can also use something.

According to the above, as shown in FIG. 5, when the vibration mode of each piezoelectric ceramic 1 and 2 causes elongation x1 in one piezoelectric ceramic 1, elongation x2 also occurs in the other piezoelectric ceramic 2, and vice versa. When one piezoelectric ceramic 1 contracts, the other piezoelectric ceramic 2 also contracts, so that stretching vibration modes in the same direction occur simultaneously on the intersecting axes. Therefore, the diaphragm 3 bonded to this is bent in one direction in the thickness direction y1 at both end portions of the vibrating piezoelectric element 1 of one length that intersect, and at the same time, the both end portions of the vibrating piezoelectric element 2 of the other length that intersect. It is bent y2 in the other direction in the thickness direction. By causing this alternately, so-called double bending vibration (torsional vibration) z is induced.

As another embodiment, as shown in FIG. 6, in the embodiment shown in FIGS. 1 to 3, one or both of the elongated piezoelectric ceramics 1, 2 are divided into two parts and arranged in the cross shape. The longitudinal vibration axes of one piezoelectric ceramic 1 and the other piezoelectric ceramic 2 intersect at the center of the rectangular diaphragm 3, and both ends of each ceramic are located at each corner of the diaphragm 3. 2 is equally divided at the center.

In this case, the multi-segmented piezoelectric ceramics 1 placed on one side of the diaphragm 3 exhibit the same vibration mode (expansion/contraction mode), and the multi-segmented piezoelectric ceramics 2 placed on the other side also exhibit the same vibration mode as the piezoelectric ceramic 1. Moreover, they exhibit the same vibration mode. That is, when one piezoelectric ceramic 1 expands, the other piezoelectric ceramic 2 also expands, and conversely, when one of the piezoelectric ceramics 1 contracts, the other also contracts.

As another example, as shown in FIGS. 7 to 11, a set of length-vibrating piezoelectric ceramics arranged so that the length-vibration directions shown in the first and second embodiments intersect is vibrated. Two sets are formed on both sides of the plate 3.

That is, a pair of piezoelectric ceramics 1a and 1b whose length vibration modes are in opposite directions are placed on both diagonals on one side of the diaphragm 3 (when one 1a expands, the other 1b contracts, and one 1a When contraction occurs, the other side 1b expands) are arranged so that their length vibration directions intersect, and the length vibration modes are in opposite directions on both diagonals on the other side of the diaphragm 3. A pair of piezoelectric ceramics 2a and 2b are arranged so that their longitudinal vibration directions intersect, and when the piezoelectric ceramic 1a arranged on one diagonal on one side of the diaphragm 3 expands, the other When the piezoelectric ceramic 2a arranged on one diagonal line on one side of the diaphragm 3 shrinks, and the piezoelectric ceramic 1b arranged on the other diagonal line on one side of the diaphragm 3 shrinks, the The piezoelectric ceramics 2b disposed on the other diagonal on the other side are arranged in combination so as to cause elongation.

The above also causes torsional vibration in the diaphragm 3 similar to that explained in FIG. 5.

8 and 9, the arrangement of the piezoelectric ceramics 1a, 1b and 2a, 2b is shown as viewed from the same direction, respectively. That is, FIG. 9 shows piezoelectric ceramics 2a and 2b on the back side of the diaphragm 3 with imaginary lines when viewed from the same direction as FIG. 8. Therefore, piezoelectric ceramics 1a and 2a face each other on the same diagonal line, and piezoelectric ceramic 1b
2b and 2b face each other on the same diagonal as described above.

FIGS. 8 to 9 show two sets of length vibrating piezoelectric ceramics 1a, 2b and 1b, arranged as described above.
10 and 11, one of the piezoelectric ceramics 1b placed on one side of the diaphragm 3 is made of a multi-segment piezoelectric ceramic, and similarly the other one side is made of a multi-segment piezoelectric ceramic. A case is shown in which one of the piezoelectric ceramics 2a disposed on the side is a multi-divided piezoelectric ceramic.

It should be noted that the present invention includes cases in which the piezoelectric ceramics 1 and 2 shown in each embodiment have a multilayer structure as described above, or the diaphragm 3 has a laminated structure.

Furthermore, the outer shape of the piezoelectric ceramic may be rectangular or strip-shaped, as well as circular or polygonal. In the case of using a rectangular diaphragm, it is not required that the length vibration axis and the diagonal line of each length vibrating piezoelectric ceramic precisely coincide with each other.

Effects of the Invention As mentioned above, piezoelectric ceramic vibrators that are currently available for industrial use basically generate vibrations in the thickness direction due to simple bending motion, or vibrations in the length direction or radial direction. Although it was limited to the vibration mode, the present invention arranges both length vibrating piezoelectric elements on one side and the other side of the diaphragm so that their length vibration directions intersect, and the both length vibrating piezoelectric elements By vibrating the length of the diaphragm so that one side and the other side of the diaphragm simultaneously expand or contract, the oscillator can be partially bent in one direction in the thickness direction and simultaneously , it was possible to generate so-called torsional vibration that is partially bent in the other direction in the thickness direction, and it was possible to provide a torsional vibrator having a unique torsional vibration mode.

The present invention can form the above-mentioned torsional vibrator with a simple structure in which elongated piezoelectric elements, etc. are arranged on one side and the other side of a diaphragm so that their lengths and vibration directions intersect. It is possible to provide a torsional oscillator that produces torsional vibration, and the laminated structure is simple.
It also has the advantage of being inexpensive.

Furthermore, the torsional oscillator according to the present invention can be easily mass-produced as described above, has stable performance, and can be suitably used in industry, for example, as a drive source for detection oscillators such as viscosity detection elements and specific gravity detectors. It is possible to provide a torsional oscillator with suitable properties.

[Brief explanation of drawings]

1 to 3 show a first embodiment of the torsional oscillator according to the present invention, FIG. 1 is a perspective view of the torsional oscillator, FIG. 2 is a side view, and FIG. 3 is a plan view. , 4th
Figure A is a side view showing the parallel connection state of the same vibrator, Figure 4B is a side view showing the same series connection state, Figure 5 is a perspective view illustrating the torsional vibration mode of the same vibrator, and Figure 6 is 7 to 9 show the third embodiment, FIG. 7 is a side view of the torsional oscillator, FIG. 8 is a plan view of the same, and FIG. FIG. 8 is a plan view showing the arrangement of piezoelectric ceramics, FIGS. 10 and 11 show the fourth embodiment, FIG. 10 is a plan view of the torsional vibrator, and FIG. FIG. 3 is a plan view showing the arrangement of piezoelectric ceramics corresponding to the above. 1, 2... Piezoelectric ceramic which is a length vibrating piezoelectric element, 3... Vibration plate.

Claims (1)

[Claims] 1 A vibrator consisting of laminated layers with a diaphragm interposed between length-vibrating piezoelectric elements, in which both the length-vibrating piezoelectric elements on one side and the other side of the diaphragm are arranged so that their length-vibrating directions intersect. The vibrating piezoelectric element is vibrated in length so as to cause simultaneous expansion or contraction on one side and the other side of the diaphragm, thereby obtaining torsional vibration of the diaphragm. A torsional oscillator.