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JPH07135695

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DESCRIPTION JPH07135695
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to
acoustic transducers suitable for use in water, and more particularly to acoustic transducers of
relatively high power.
[0002]
2. Description of the Related Art In general, an acoustic transducer of this type has an active
columnar body in which a plurality of electrostrictive vibrators are stacked, and a housing which
supports the active columnar body and which covers in a watertight manner. The housing is
provided with a housing tube having an oval cross-section, and supports both ends of the active
columnar body in the stacking direction from the major axis direction of the oval. The housing
tube then functions as an acoustic emission surface. Further, a watertight connector is attached
to the housing, to which a cable is connected, and a drive signal is sent from the ship or the
ground to the electrostrictive vibrator.
[0003]
FIG. 4 is a diagram for explaining the operating principle of the acoustic transducer. In FIG. 4,
when a drive signal is applied to the electrostrictive vibrator, the active columnar body is excited
in the same direction as the stacking direction of the electrostrictive vibrator, that is, in the long
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axis direction of the tube 310 (arrow B). Then, the vibration displacement in the long axis
direction is converted as vibration displacement in antiphase of the short axis direction (arrow S)
of the housing tube 310 by the flexibility of the ellipse, and the sound wave is emitted from the
housing tube 310 (acoustic radiation surface) .
[0004]
Therefore, the larger the vibration displacement of the active columnar body, the larger the
vibration displacement of the acoustic radiation surface, and a higher output can be obtained.
And, in order to obtain such a high output, as a material of the electrostrictive vibrator which is
the drive source, a piezoelectric constant d representing a ratio of an applied electric field to a
strain, and a piezoelectric representing a ratio of an applied electric field to a stress It is
preferable to use one having a large constant e and a large relative dielectric constant.
[0005]
By the way, when the acoustic transducer is driven, the electrostrictive vibrator generates heat
due to the mechanical resistance inside the electrostrictive vibrator to be excited. Due to this heat
generation, when the temperature of the electrostrictive vibrator reaches the Curie temperature,
the characteristics of the electrostrictive vibrator deteriorate, causing a problem such as a
malfunction of the acoustic transducer. For this reason, even if the above-mentioned constant
and relative permittivity are relatively high, materials having a low Curie temperature are not
suitable for conventional acoustic transducers, in particular, high-power acoustic transducers
that generate a large amount of heat from an electrostrictive vibrator. There is a problem.
[0006]
Another object of the present invention is to prevent the characteristic deterioration of the
electrostrictive vibrator due to the heat generation of the electrostrictive vibrator and to improve
the reliability of the acoustic transducer.
[0007]
Yet another object of the present invention is to provide a relatively high-power acoustic
transducer that can use materials with low Curie temperature that could not be used so far.
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[0008]
SUMMARY OF THE INVENTION According to the present invention, there is provided an acoustic
transducer having an active columnar body provided with a plurality of electrostrictive vibrators
stacked with a heat dissipation structure interposed therebetween.
[0009]
Further, according to the present invention, there can be obtained the acoustic transducer in
which the active columnar body sandwiches the heat dissipation structure so as to bisect the
plurality of electrostrictive vibrators in the stacking direction.
[0010]
According to the invention, the acoustic transducer also comprises a housing covering the active
pillars, the heat dissipation structure being in contact with the housing forming a heat dissipation
path from the active pillars to the housing The acoustic transducer is obtained.
[0011]
That is, according to the present invention, the electrostrictive vibrator vibrates in the
configuration in which the heat dissipation structure is inserted at the center of the stacking
direction of the active columnar body in which the electrostrictive vibrators are stacked, that is,
the position of vibration displacement is zero. It is characterized in that the heat generated at that
time is dissipated into water through this heat dissipation structure, and the heat generation
temperature of the vibrator can be kept below the Curie temperature.
[0012]
An acoustic transducer according to an embodiment of the present invention will be described
below with reference to the drawings.
[0013]
FIG. 1 is a perspective view showing the structure of an acoustic transducer according to the
present embodiment.
In FIG. 1, the present acoustic transducer is formed by laminating a plurality of electrostrictive
vibrators, and has an active columnar body 10 having a NODE portion 11 described later and an
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H-shaped side shape, and its central leg 21 is an active columnar The heat dissipation structure
20 is in contact with the NODE portion 11 of the body 10, and the housing 30 supports the
active columnar body 10 and covers the lid while maintaining watertightness.
[0014]
The housing 30 has a cylindrical housing tube 31 having an oval cross section, and plate-like end
plates 32 and 33 watertightly attached to both open ends of the housing tube 31.
The housing tube 31 supports both ends of the active columnar body 10 in the stacking direction
from the major axis direction of the elliptical shape.
The housing tube 31 then functions as an acoustic radiation surface.
Further, end legs 22 and 23 formed at both ends of the central leg 21 of the heat dissipation
structure 20 are in contact with the end plates 32 and 33, respectively.
Further, a watertight connector 40 is attached to the end plate 32, and a cable is connected, and
a drive signal is sent from the ship or the ground to the electrostrictive vibrator.
[0015]
FIG. 2 is a conceptual view for explaining the vibration operation of the active columnar body 10.
In FIG. 2, the conceptual active columnar body 100 is formed by laminating a plurality of
electrostrictive vibrators.
When a drive signal is applied to the electrostrictive vibrator, the active columnar body 100
vibrates in the stacking direction of the electrostrictive vibrator. The vibration displacement is as
shown by a curve shown in the figure for each position of the active columnar body 100. The
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NODE part mentioned above refers to the position where the vibration displacement is 0 among
the plurality of electrostrictive vibrators. In other words, the NODE portion is the central portion
of the active columnar body 100 in the excitation direction.
[0016]
FIG. 3 is a conceptual view showing the heat radiation path of the acoustic transducer according
to the present embodiment. In FIG. 3, the heat generated from the electrostrictive vibrator that is
excited by the application of the drive signal is along the path shown by the arrow in the figure,
that is, the central leg 21 of the heat dissipation structure 20, the end legs 22 and 23, the
housing The heat is transmitted to the 30 end plates 32 and 33 and dissipated into water.
[0017]
In the present embodiment, a flexural vibration mode using an elliptical housing is taken as an
example, but as for acoustic transducers using other vibration modes, the present invention is
also applicable if an active columnar body having a NODE portion is used. Is an effective means.
[0018]
In the acoustic transducer according to the present invention, since the plurality of
electrostrictive vibrators are stacked with the heat dissipation structure interposed therebetween,
the heat generated by the excitation of the electrostrictive vibrator is dissipated, and the
characteristics of the electrostrictive vibrator are thereby obtained. Deterioration is prevented
and reliable.
[0019]
Moreover, by sandwiching the heat dissipation structure so as to divide the plurality of
electrostrictive vibrators in the stacking direction, the excitation of the electrostrictive vibrators
is not inhibited.
[0020]
In addition, the heat generated by the excitation of the electrostrictive vibrator can be dissipated
into the water by forming the heat radiation path from the active columnar body to the housing
by bringing the heat radiation structure into contact with the housing, and the heat radiation
effect can be further improved. .
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[0021]
Furthermore, according to the heat radiation effect of the present invention, materials which can
not be used so far due to the characteristic deterioration due to excitation heat generation, for
example, materials having large piezoelectric constants and specific dielectric constants but low
Curie temperature, etc. High output of the acoustic transducer can be expected.
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