JPS63151298

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DESCRIPTION JPS63151298
[0001]
FIELD OF THE INVENTION The present invention relates to a torsional oscillator that converts
electrical strain change in a longitudinal direction (longitudinal vibration) into mechanical
vibration in a thickness direction. Prior Art A vibrator (piezoelectric bimorph) in which a metal
plate is bonded to a piezoelectric ceramic is known as one that converts length vibration into
mechanical vibration in the thickness direction by utilizing the characteristics of the piezoelectric
ceramic that vibrates in length by voltage application. It is done. In addition, a vibrator is used
that bonds two piezoelectric ceramics so that the expansion and contraction direction at the time
of voltage application is in opposite directions, extends in one and alternately generates
contraction in the other, thereby converting it into mechanical vibration in the thickness
direction. It is provided. The above-mentioned piezoelectric ceramic is obtained by applying a
high voltage to a ferroelectric ceramic having spontaneous polarization and fixing the
polarization direction in one direction, that is, so-called polarization processing (poling
processing). In the above-described piezoelectric ceramic vibrators, the vibration operation in the
thickness direction at the time of voltage application is a simple bending motion, regardless of
the problems to be solved by the invention. Therefore, the above-mentioned piezoelectric ceramic
vibrator is narrowed to applications in which bending motion is a vibration source, for example,
limited applications such as electroacoustic transducers and piezoelectric filters. As described
above, conventional piezoelectric ceramic is basically limited to vibration of length such as
bending motion source as described in 2), vibration in thickness direction, or vibration mode in
radial direction. However, according to the present invention, the above-mentioned piezoelectric
ceramic has different direction multi-layer curvature, so that the so-called torsional vibration in
which the piezoelectric ceramic is partially bent in one of the thickness direction and at the same
time partially bent in the other is generated. It is an object of the present invention to provide an
industrially suitable torsional oscillator having an inherent vibration mode. This is intended to
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expand the application of the piezoelectric ceramic to a new field utilizing the above-mentioned
torsional vibration mode, and to provide one having richness as a detection transducer such as a
viscosity detection element or a hydrometer. Means for Solving the Problems The present
invention is, as means for solving the above problems, a vibrator comprising a diaphragm
interposed between piezoelectric elements vibrating in a length and laminated, which comprises
one side and the other side of the diaphragm. The two length vibration piezoelectric elements on
the surface side are disposed so that the length vibration direction crosses, so that the two length
vibration piezoelectric elements simultaneously extend or simultaneously shrink on one surface
side and the other surface side of the diaphragm. By vibrating the diaphragm, the torsional
vibration of the diaphragm is obtained. According to the present invention, when the vibration
mode of the two crossing piezoelectric elements shrinks at one crossing piezoelectric element,
the other crossing piezoelectric element simultaneously shrinks at the same time, and conversely
stretches at one side. At the same time, at the same time elongation occurs on the other side, and
in each piezoelectric element, stretching vibration modes in the same direction occur in
combination.
Therefore, the diaphragm bonded to this is bent in one thickness direction at both end portions
of the intersecting one length vibration piezoelectric element, and the other in the thickness
direction at the both ends of the other length vibrating piezoelectric element simultaneously
crossed. It will be bent. By alternately producing this, so-called double bending vibration (torsion
vibration) is induced. EXAMPLES Examples of the present invention will be described with
reference to the drawings. As a piezoelectric element, a piezoelectric ceramic to which
piezoelectricity is imparted by subjecting a ferroelectric ceramic to poling treatment (poling
treatment) as described above is used. The polarization process is a process of fixing the
polarization direction in one direction, and depending on the polarization direction, the extension
or contraction direction (long vibration direction) with respect to the positive voltage or the
negative voltage is reverse. As shown in FIGS. 1 to 11, the present invention is a vibrator formed
by laminating the vibrating plate 3 between the piezoelectric ceramics 1 and 2 vibrating in the
above length and laminating them, and one side of the vibrating plate 3 The two length vibration
piezoelectric ceramics 1.2 on the other surface side are disposed so that the length vibration
direction crosses, and both length vibration piezoelectric ceramics 1 and 2 simultaneously extend
on one side and the other surface of the diaphragm 3 Alternatively, it is configured to vibrate in
length so as to cause contraction and obtain torsional vibration of the diaphragm 3. Specifically,
as shown in FIG. 1 to FIG. 3 (first embodiment), a pair of elongated piezoelectric ceramics 1.2
having a strip shape vibrating longitudinally in the longitudinal direction is prepared, The
elongated piezoelectric ceramic 1 is attached to one side of the rectangular diaphragm 3, and the
other elongated piezoelectric ceramic 2 is attached to the other surface of the diaphragm 3. One
elongated piezoelectric ceramic 1 is attached to one side of the diaphragm 3 The other elongated
piezoelectric ceramic 2 is disposed on the other diagonal of the diaphragm 3 so that the
longitudinal vibration directions of both elongated piezoelectric ceramics 2 cross each other. The
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piezoelectric ceramics 1.2 cross each other at the center of the rectangular diaphragm 3 and are
located at the corners of the diaphragm 3 whose opposite ends are diagonally located. As shown
in FIG. 4A, in the case of parallel connection, both elongated piezoelectric ceramics 1 and 2 are
pasted on one side and the other side of the diaphragm 3 so that their polarization directions P
are opposite to each other. Form a crossover state. Further, as shown in FIG. 4B, in the case of
series connection, the elongated piezoelectric ceramics 1 and 2 are respectively laminated on the
diaphragm 3 in the cross arrangement so as to have the same polarization direction. Although
the above-mentioned piezoelectric ceramics 1 and 2 have a single layer structure, bending
motion is caused by using a plurality of ceramic bimorphs utilizing the characteristics of the
piezoelectric ceramic vibrating in length as described above. You may use a thing.
According to the above, as shown in FIG. 5, when the vibration mode of each piezoelectric
ceramic 1.2 produces elongation xl in one piezoelectric ceramic 1, the other piezoelectric ceramic
2 also produces elongation x2, conversely one piezoelectric When the ceramic 1 shrinks, the
other piezoelectric ceramic 2 also shrinks so that stretching vibration modes in the same
direction simultaneously occur on the cross axis. Therefore, the diaphragm 3 bonded to this is
bent y1 in one side in the thickness direction at both end portions of the intersecting one length
vibration piezoelectric element 1, and at the both end portions of the other length vibrating
piezoelectric element 2 simultaneously crossed. The other side in the thickness direction is bent
y2. By alternately producing this, so-called double bending vibration (torsion vibration) Z is
induced. Further, as shown in FIG. 6 as another embodiment, in the embodiment of FIGS. 1 to 3,
one or both of the elongated piezoelectric ceramics 1.2 are divided into two and disposed in the
cross shape. The length oscillation axis of one piezoelectric ceramic 1 and the other piezoelectric
ceramic 2 crosses at the center of the rectangular diaphragm 3, and both ceramic ends are
located at each corner of the diaphragm 3, respectively. 1, 2 are equally divided in the center. In
this case, the divided piezoelectric ceramic 1 disposed on one side of the diaphragm 3 exhibits
the same vibration mode (stretching mode), and the other divided piezoelectric ceramic 2
disposed on the other side also has the same direction as the piezoelectric ceramic 1. And
mutually show the same vibration mode. That is, when one piezoelectric ceramic 1 is stretched,
the other piezoelectric ceramic 2 is also stretched simultaneously, and conversely, when one is
contracted, the other is also contracted. As another embodiment, as shown in FIG. 7 to FIG. Two
sets of length vibration piezoelectric ceramics arranged so as to cross the length vibration
direction shown in the second embodiment are formed on both sides of the diaphragm 3. That is,
the vibration is made on both diagonal sides of the diaphragm 3 on one side. A pair of
piezoelectric ceramics la and 1b whose motion modes are opposite to each other (when one
stretches, the other shrinks, and when one shrinks, the other stretches) The length vibration
directions cross each other, and the length vibration directions cross the pair of piezoelectric
ceramics 2a and 2b whose length vibration modes are opposite to each other on both diagonals
on the other side of the diaphragm 3. When the piezoelectric ceramic 1a arranged on one side
diagonal of one side of the diaphragm 3 is stretched, the piezoelectric ceramic 2a arranged on
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the other diagonal side of the other side corresponding thereto is stretched. And when the
piezoelectric ceramic 1b disposed on the other diagonal on one side of the diaphragm 3 shrinks,
the corresponding piezoelectric ceramic disposed on the other diagonal on the other side 2b is
growing The combination placed in so that.
Also in the above case, the same torsional vibration as described in FIG. In order to facilitate
understanding, in FIG. 8 and FIG. 9, the arrangement of the piezoelectric ceramic la, lb and 2a, 2b
is shown in plan view from the same direction. That is, FIG. 9 shows the piezoelectric ceramics 2a
and 2b on the back side of the diaphragm 3 in phantom lines when viewed from the same
direction as FIG. Therefore, the arrangement of the above description is shown in which the
piezoelectric ceramics 1a and 2a face each other on the same diagonal line, and the piezoelectric
ceramics 1b and 2b face each other on the same diagonal line. 8 to 9 show two sets of length
vibration piezoelectric ceramic la, 2b and lb arranged as described above. 10 and 11, each of the
pair of piezoelectric ceramics 1b disposed on one side of the diaphragm 3 is made to be a
plurality of divided piezoelectric ceramic, and the other side is similarly formed. The case where
one of the piezoelectric ceramics 2a arrange ¦ positioned at the side is made into a double
division piezoelectric ceramic is shown. The present invention includes the case where each of
the piezoelectric ceramics 1 and 2 shown in each embodiment has a multilayer structure as
described above, or the diaphragm 3 is used in a laminated structure. In addition, the outer shape
of the piezoelectric ceramic may be square, band-like, circular, polygonal or the like. When using
a square diaphragm, each length vibrating piezoelectric ceramic does not require that the length
vibration axis and the diagonal exactly match. Effect of the Invention As described above, what is
currently provided as a commercially available piezoelectric ceramic vibrator is basically
vibration in the thickness direction by simple bending motion, or length vibration, radial
vibration or the like. Although the present invention is limited to the vibration mode, the present
invention arranges both length vibration piezoelectric elements on one side and the other surface
of the above diaphragm so that the length vibration direction crosses, and both length vibration
piezoelectric elements The above-mentioned different-direction restoring curvature is realized by
simultaneously vibrating the length on one side and the other side of the diaphragm so as to
simultaneously expand or simultaneously shrink, and the vibrator is partially bent in one of the
thickness directions. A so-called torsional vibration can be generated which is partially bent in
the other of the thickness direction, and a torsional vibrator having an inherent torsional
vibration mode can be provided. According to the present invention, the above-mentioned
torsional vibrator can be formed with a simple configuration in which elongated piezoelectric
elements and the like are arranged on one side and the other side of the diaphragm so that the
length vibration direction crosses. Since a torsional vibrator can be provided in which torsional
vibration can be obtained, and the laminated structure is simple, the cost is also inexpensive.
In addition, the torsional vibrator according to the present invention facilitates mass production
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as described above and has stable performance and can be industrially suitably used. For
example, as a drive source of a detection vibrator such as a viscosity detection element or a
specific gravity detector It is possible to provide a torsion oscillator having aptitude.
[0002]
Brief description of the drawings
[0003]
1 to 3 show a first embodiment of a torsional vibrator according to the present invention, FIG. 1
is a perspective view of the torsional vibrator, FIG. 2 is a side view, and FIG. 3 is a plan view 4A is
a side view showing the parallel connection of the vibrator, FIG. 4B is a side view showing the
serial connection, and FIG. 5 is a perspective view for explaining the torsional vibration mode of
the vibrator; FIG. 6 is a plan view of a torsional vibrator showing a second embodiment, FIGS. 7
to 9 show a third embodiment, FIG. 7 is a side view of the torsional vibrator, FIG. 8 is a plan view
thereof, FIG. 9 is a plan view of the arrangement of the piezoelectric ceramic corresponding to
FIG. 8, FIG. 10 and FIG. 11 show the fourth embodiment, FIG. 10 is a plan view of a torsional
vibrator, and FIG. FIG. 11 is a plan view of the arrangement of the piezoelectric ceramic
corresponding to FIG.
1.2 · · · Piezoelectric ceramic that is a length vibration piezoelectric element, 3 · · · diaphragm.
Figure 1 Figure 2 Figure 4 (A) Figure 4 (B) Figure 5-y2 Figure 8 Figure 9 Figure 10
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