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JPH04265099

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DESCRIPTION JPH04265099
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
acoustic transducer employing a sliding vibration differential type mainly for receiving a broad
band.
[0002]
2. Description of the Related Art Heretofore, this type of acoustic transducer has a plurality of
block-shaped piezoelectric vibrators 10 stacked in two rows in a rectangular parallelepiped
casing 50, as shown in FIG. A plurality of T-shaped leg portions obtained by bonding the blockshaped sound receiving plate 20 juxtaposed in parallel to the unit rows of the piezoelectric
vibrator 10 are interposed with the buffer material 30 around them, and the sound is received.
The plates 20 are embedded side by side so as to be exposed on one surface of the housing 50.
That is, the piezoelectric vibrator 10 is placed between the sound receiving plate 20 and the
housing 50, and the bonding surfaces of the piezoelectric vibrator 10 are bonded with an
adhesive.
[0003]
Further, since the bonding surface of each piezoelectric vibrator 10 is an electric positive surface,
the bonding surface of each piezoelectric vibrator 10 to the casing 50 and the sound receiving
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plate 20 is a negative surface, so that piezoelectric vibration is generated. In the space (air
chamber 8) formed in the vicinity of the element 10, lead wires 7a and 7b for applying positive
and negative electrodes are disposed. The lead wire 7 a connects the housing 50 to the joint
surface of the piezoelectric vibrators 10, and the lead wire 7 b is used to connect the housing 50
to the sound receiving plate 20.
[0004]
More specifically, as shown in FIG. 6, such an acoustic transducer is a combination of two
piezoelectric vibrators 10 made of piezoelectric ceramic and has a width W, a length L, and a
height. The bonding surfaces 120a to 120c are formed by the surfaces of these LW surfaces or
their bonding portions. Among these, the bonding surface 120 b is to be a positive electrode
surface, and the bonding surfaces 120 a and 120 c are to be a negative electrode surface.
[0005]
That is, a transducer having such a configuration constitutes, for example, a piezoelectric
conversion mode of longitudinal effect so that broadband reception can be performed with high
sensitivity even in water. The parallel arrangement polarizes the electrical polarity to positive or
negative for each piezoelectric vibrator 10, while the repulsive force between the positive
electrodes acts on the joint surface 120b, and as a result, the reciprocal polarization P is made in
the perpendicular direction (H direction) to each electrode surface By applying stress T in the
same direction as this reciprocal polarization P, an electrical signal as an output can be obtained.
[0006]
In the case of the conventional acoustic transducer, since each electrode surface is parallel to the
LW surface, the piezoelectric vibrator 10 itself has a repulsive force generated at the bonding
surface 120b. Because not only the direction perpendicular to the LW plane but also the
direction perpendicular to the HW plane and the LH plane are generated by the action of {circle
over (1)}, the piezoelectric conversion modes of the transverse effect are generated and are
mixed in the piezoelectric conversion modes of the longitudinal effect as a result In the case of
using the piezoelectric conversion mode of the longitudinal effect, there is a problem that
transmission with high fidelity and reception with high sensitivity can not be performed.
[0007]
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FIG. 7 shows the gain sensitivity change G of the stress electric signal with respect to the
frequency change F when the wide band transmission SV and the reception RV are performed in
this kind of acoustic transducer.
Here, in order to obtain a stress signal in the H direction for a transducer having a piezoelectric
conversion mode of longitudinal effect, fr (H), which is its resonance frequency, is generated in
the other direction, fr (W) or fr It explains that it is necessary to make it lower than (L).
[0008]
Specifically, in order to satisfy such requirements, it is necessary to make the length L of the
combination of the piezoelectric vibrators 10 shorter than the height H.
Therefore, under the present circumstances, in order to obtain a desired acoustic radiation
surface length, it is considered effective to configure the piezoelectric vibrator 10 in an assembly
type that can be divided.
[0009]
However, the piezoelectric conversion mode of the general longitudinal effect includes the
piezoelectric distortion constant d (the amount of distortion per unit electric field) as a parameter
for the gain sensitivity of the transmission SV and the gain sensitivity of the reception RV. The
piezoelectric output constant g (electric field strength per unit stress), which is a parameter to
the parameter, is defined as d33 and g33, respectively, and is lower than these constants d15
and g15 when sliding vibration is used for the piezoelectric vibrator. As a result, the fidelity of
the transmission SV and the gain sensitivity of the reception RV are reduced as a result.
[0010]
The present invention has been made in view of the above circumstances, and an object thereof
is to provide an acoustic transducer which can relax the restriction of dimensions and can be
simply configured and can perform mainly high sensitivity reception. It is in.
[0011]
SUMMARY OF THE INVENTION According to the present invention, by means of two electrodes
provided on both sides of a rectangular parallelepiped piezoelectric ceramic, the plane including
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the width and the length direction is provided. And a plurality of piezoelectric vibrators that are
polarized in the vertical height direction, and elastic bodies, each having a side cross section for
inserting each of the piezoelectric vibrators, and a plurality of wave-sensing fronts that are
exposed for transmission of received waves. A housing having a T-shaped sound receiving plate,
a housing groove for storing each piezoelectric vibrator and each T-shaped sound receiving plate
as a combined body, and a relatively central portion of each piezoelectric vibrator. A lead wire
electrically connecting each electrode of the piezoelectric vibrator to be set, and a shock
absorbing material interposed between the combination body and the storage groove to give
sliding vibration to each piezoelectric vibrator in the height direction An acoustic transducer is
provided.
[0012]
In an embodiment, the housing is provided with a plurality of storage grooves capable of storing
a plurality of combinations, and a buffer material is interposed in each storage groove, and the
electric polarity of each electrode is set to a height. Each piezoelectric vibrator placed in the
center of each combination in a relatively central position after inserting each piezoelectric
vibrator into the leg portion of each T-shaped sound receiving plate so as to coincide with
opposite directions in the direction An acoustic transducer is obtained in which each of the wavesensing surfaces of the T-shaped sound-receiving plates are adjacent to each other while being
electrically connected to the electrodes included in each and each combination is accommodated
in each storage groove.
[0013]
EXAMPLES The acoustic transducer of the present invention will be described in detail with
reference to the following examples.
FIG. 1 is a perspective view showing the configuration of an acoustic transducer according to an
embodiment of the present invention.
[0014]
As shown in the drawing, the acoustic transducers are provided in the housing 5 and the
piezoelectric transducers of rectangular parallelepipeds are provided separately for the two
storage grooves in a state in which the buffer members 3A and 4A and the buffer members 3B
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and 4B are stored separately. Six piezoelectric vibrators 1A to 1F made of ceramic, and four Tshaped sound receiving plates 2A to 2D into which these piezoelectric vibrators 1A to 1F are
inserted and which have an exposed sound sensing surface It accommodates two rectangular
combination bodies respectively combined in equal division.
That is, the two rectangular parallelepiped combination bodies here are one comprising the
piezoelectric vibrators 1A to 1C and the T-shaped sound receiving plates 2A and 2B, the
piezoelectric vibrators 1D to 1F and the T-shaped sound receiving plate 2C and It is divided
roughly into what consists of 2D.
[0015]
Among these, the buffer members 4A and 4B respectively interposed between each rectangular
parallelepiped combination body and the two storage grooves have a width W and a length of
each of the piezoelectric vibrators 1A to 1F formed of rectangular parallelepipeds. It is provided
to give sliding vibration in a direction (height H direction) perpendicular to a plane including the
L direction (LW plane).
The T-shaped sound receiving plates 2A and 2B and the T-shaped sound receiving plates 2C and
2D are side cross sections for inserting the piezoelectric vibrators 1A to 1C and the piezoelectric
vibrators 1E to 1F, respectively, and They are individually exposed to be used for wave
transmission, and have sensing surfaces adjacent to each other in a rectangular combination.
[0016]
On the other hand, each of the piezoelectric vibrators 1A to 1F is polarized in one of the
directions of height H by electrodes provided at diagonal positions on both sides in the direction
of height H on the dimension thereof. It is.
For this reason, the piezoelectric vibrators 1A to 1F are fitted into the legs of the T-shaped sound
receiving plates 2A to 2D so that the electrical polarities of the respective electrodes coincide in
mutually opposite directions in the height H direction. It is done.
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[0017]
Specifically, the dimensions of each of the piezoelectric vibrators 1A to 1F are defined by the
width W, the length L, and the height H, respectively, and the electrodes of the piezoelectric
vibrators 1A to 1F have the same dimensions. As shown in FIG. 1, while lead wires 6A and 6A
'having negative and positive electric polarities are connected to the piezoelectric vibrator 1B in
order to obtain a differential output, the piezoelectric vibrator 1E is electrically connected to each
other. The lead wires 6B and 6B 'of which polarity is negative and positive are connected.
[0018]
FIG. 2 shows the configuration of the piezoelectric vibrator 1B among the piezoelectric vibrators
1A to 1F. The piezoelectric vibrator 1B is provided with electrodes 12a and 12b on both sides of
a rectangular parallelepiped. .
Among these, as described above, the electrode 12a is connected to the negative electrode by the
lead wire 6A ', and the electrode 12b is connected to the positive electrode by the lead wire 6A.
[0019]
The acoustic transducer having such a configuration is characterized in that the piezoelectric
vibrators 1A to 1C and 1D to 1F between the positive and negative electrodes are interposed
between the legs of the T-shaped sound receiving plates 2A to 2D. Since the relative repulsion
acts and the piezoelectric vibrators 1A to 1F are polarized P in the direction coincident with the
direction of the stress T1, the stresses T1 in mutually opposite directions in the height H
direction perpendicular to the LW plane are generated. By adding T2 and T2, an electric signal as
an output can be obtained from the piezoelectric vibrators 1B and 1E. This means that the
piezoelectric vibrator 1B and the piezoelectric vibrator 1E receive differential outputs with
respect to the piezoelectric vibrators 1A and 1C and the piezoelectric vibrators 1D and 1F when
receiving waves, respectively. ing.
[0020]
FIG. 3 shows the gain sensitivity change G of the stress electric signal with respect to the
frequency change F when the transmission SV of the high frequency band and the reception RV
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of the wide band are performed in such a sliding vibration differential type acoustic transducer.
Is shown. That is, in the sliding vibration differential type acoustic transducer, since the buffer
members 4A and 4B are interposed to give sliding vibration to each of the piezoelectric vibrators
1A to 1F, the resonance frequency is only fr (W) in the width W direction. The other values of fr
(H) in the direction of height H and fr (L) in the direction of length L are not piezoelectrically
converted.
[0021]
In this case, the height H and the length L of each of the piezoelectric vibrators 1A to 1F can be
arbitrarily selected, and when the width W is thin, the resonant frequency fr (W) is high. While it
is also suitable as a high-frequency wave transmitter, it is particularly sensitive to the hydrostatic
pressure below the resonance frequency fr (W) as shown for example in the wave reception RV
of FIG. It means that it can be broadened.
[0022]
By the way, according to the acoustic transducer of the present invention, the piezoelectric
vibrator 1B or 1E is in the state of being interposed between the legs of the T-shaped sound
receiving plates 2A and 2B or the legs of the T-shaped sound receiving plates 2C and 2D. When
the output is taken out, the differential outputs for the piezoelectric vibrators 1A and 1C and the
piezoelectric vibrators 1D and 1F are obtained. It can be determined by comparing the phases of
the outputs.
[0023]
FIG. 4 (A) illustrates the sliding vibration in the combination including the piezoelectric vibrators
1A and 1B in the vicinity of the T-shaped sound receiving plate 2A of the acoustic transducer of
the present invention, and FIG. 4 (B) The longitudinal vibration in the T-shaped combination body
composed of the sound receiving plate 20 and the piezoelectric vibrator 10 of the conventional
acoustic transducer will be described.
[0024]
In the acoustic transducer of the present invention, as shown in FIG. 4A, since the combination of
the state in which the piezoelectric vibrators 1A and 1B are inserted into the T-shaped sound
receiving plate 2A causes sliding vibration, sliding vibration is caused. Thus, the combined
distortion of the distortion ξa generated in the piezoelectric vibrator 1A and the distortion 生 じ
る b generated in the piezoelectric vibrator 1B corresponds to the distortion に お け る in the
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sound sensing surface of the T-shaped sound receiving plate 2A.
On the other hand, in the conventional acoustic transducer, as shown in FIG. 4B, distortion ξc
generated between the sound receiving plates 20 stacked in two layers by the longitudinal
vibration is directly detected in the wave-sensing surface of the piezoelectric vibrator 10. It
corresponds to distortion ξ.
[0025]
That is, assuming that the sliding vibration modes in the acoustic transducer of the present
invention are d15 and g15, they are 1.5 to 2.0 times as large as those of the conventional vertical
vibration modes (the piezoelectric constants d33 and g33 of the longitudinal effect). The
sensitivity of the
The configuration of the rectangular parallelepiped combination body is two T-shaped sound
receiving plates and three piezoelectric vibrators fitted in the legs, but is not limited thereto.
[0026]
As described above, according to the present invention, by making the sound receiving plate Tshaped and incorporating the piezoelectric vibrator, the dimensions regarding the height and
length of the piezoelectric vibrator can be set arbitrarily. Thus, it is possible to simplify the
construction of a sliding vibration differential type acoustic transducer which can be selected to
perform highly sensitive reception.
In particular, since lead wires are selectively drawn out from each of the electrodes of a plurality
of built-in piezoelectric vibrators, relative directions can be obtained by comparing the direction
of incoming waves with the phase of the differential output of each rectangular combination. Can
be determined. Moreover, since it senses to the resonant frequency or less for receiving waves,
the use in water becomes effective conventionally. Furthermore, it can also be used for
transmission in a high frequency band.
[0027]
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Brief description of the drawings
[0028]
1 is a perspective view showing the configuration of a sliding vibration differential acoustic
transducer according to an embodiment of the present invention.
[0029]
2 shows the configuration of a single piezoelectric vibrator among the piezoelectric vibrators.
[0030]
FIG. 3 shows the electrical characteristics of the acoustic transducer according to the present
invention with regard to transmission and reception in terms of the change in gain sensitivity of
the stressed electrical signal with respect to the change in frequency.
[0031]
FIG. 4 Distortions in the wave-sensing surface of the present invention or a conventional acoustic
transducer are shown for comparison and explanation.
[0032]
FIG. 5 is a partially cutaway view of the configuration of the conventional acoustic transducer.
[0033]
6 shows the configuration of a piezoelectric vibrator alone in a conventional acoustic transducer.
[0034]
FIG. 7 shows the electrical characteristics of transmission and reception in the conventional
acoustic transducer in relation to the change in gain sensitivity of the stressed electrical signal
with respect to the change in frequency.
[0035]
Explanation of sign
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[0036]
1A to 1F, 10 Piezoelectric vibrators 2A to 2D, 20 Sound receiving plates 3A, 3B, 4A, 4B, 30
Buffer members 5, 50 Housings 6A, 6A ', 6B, 6B', 7a, 7b Lead wire 8 Air chamber
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