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JPH02238799

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DESCRIPTION JPH02238799
[0001]
[Industrial field of application] The present invention relates to a transducer for sonar.
[Description of the Related Art] A conventional sonar transducer of this type has an electricalmechanical conversion element 9 attached to one end of a resonance tube 6 as shown in FIG. 5,
and an electrical signal input from lead wires 11a and 11b is mechanical It has a structure that
converts it into vibration. Since the electro-mechanical transducer 9 has the piezoelectric plate 8
bonded to one side of the diaphragm 7 as shown in FIG. 6 and vibrates in the deflection mode,
the mechanical resonance frequency can be lowered. Since the vibration of both sides of the is in
opposite phase, it is necessary to provide a path difference of more than on / 2 (in is the
wavelength of the sound wave of the medium in the tube) between both sides to prevent shortcircuit phenomenon of sound waves radiated from both sides. In addition, since the deflection
mode electromechanical conversion element 9 has low frequency resonance, the underwater
wavelength is longer than the diameter D of the radiation surface, and the acoustic load is small,
so that the conversion efficiency is low. As a countermeasure against these problems, the
conversion efficiency is improved by attaching the resonance tube 6 to one side of the electric-tomechanical converter 9 and setting the length of the resonance tube to 4/4. The sound pressure
distribution and velocity distribution inside the resonance tube 6 are as shown by the solid line
and the dotted line in FIG. 7, and a high acoustic load of in / out antiresonance is applied to the
back surface of the electro-mechanical transducer 9 Since the sound wave emitted from the open
end of the resonance tube 6 is added in the same phase, the acoustic load on the surface is also
high. As a result, it was a low frequency, efficient transducer with directivity as shown in Fig.8.
[Problems to be Solved] If the rigidity of the resonance tube 6 is low, the above-mentioned
conventional sonar transducer is insufficiently puffed and the acoustic load and efficiency can
not be improved due to the sound wave transmitted through the tube wall. If the rigidity is
increased, there arises a problem that the resonance tube 6 becomes thick and heavy. The
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present invention has been made in view of the above-mentioned problems, and an object thereof
is to provide a low frequency, high efficiency and lightweight sonar transducer. [Solution to the
Problems] In order to achieve the above object, a transducer for a sonar according to the present
invention comprises an acoustic resonance circuit with at least one surface of mechanical
vibration surfaces of an electrical-mechanical conversion element, The structure of the
mechanical conversion element and the structure of the acoustic resonance circuit are shared. An
embodiment of the present invention will be described below with reference to the drawings. FIG.
1 is a perspective view of an embodiment of the present invention, and FIG. 2 is a plan view
thereof. The transducer 1 of this embodiment forms a hollow triangular column body by using
three electromechanical conversion elements 4a to 4C in which the piezoelectric plates 3a to 3C
are bonded to one side of the diaphragms 2a to 2C, respectively. The interior of is configured as
an acoustic resonance circuit longer than half a wavelength (in / 2).
Each of the electric-to-mechanical conversion elements 4a to 4C includes lead wires 10a. In
accordance with the electric signal input from the fob, a bending vibration is generated with the
junction point of each of the electric-mechanical conversion elements 4a to 4C as shown by the
one-dot chain line and the dotted line in FIG. Accordingly, sound waves of opposite phase are
emitted to the inner and outer surfaces of the triangular cylinder transducer 1, and the sound
waves emitted to the inner surface are vibrated with the side walls of the acoustic resonance
circuit (i.e., the electro-mechanical transducers 4a to 4c) in phase. Therefore, the light propagates
to the upper and lower open ends without passing through the side wall, and is emitted from the
open end to the outside. When the sound waves inside the transducer 1 are radiated from the
upper and lower open ends, the phase is delayed by the time when they are propagated inside,
and they are adjusted to the same phase as the external sound waves. The sound pressure
distribution and velocity distribution when viewed from the center position inside the transducer
l are shown by the solid and dotted lines in Fig. 3. Actually, the radiation inside the transducer 1
is from the upper end to the lower end, and the phase adjustment of the internal sound wave
over the entire length (that is, the adjustment of propagation time) is performed for the sum of
each end of the internal sound wave. The length of the device l is longer than half wavelength. In
this way, the internal sound pressure radiated from the upper and lower end faces of the
transducer 1 and the external sound pressure radiated directly from the upper and lower end
faces of the transducer 1 and the horizontal directivity of isotropy as shown in FIG. It becomes an
efficient low frequency transducer with sufficient acoustic load. Further, the side walls of the
acoustic resonance circuit are lightweight because they exhibit complete puff fullness even if
they are thin, since the electro-mechanical transducers 4a to 4C themselves are vibrating bodies.
In addition, although it was set as the transducer of the triangular prism body comprised with
three sheets of electric-mechanical transducer elements 4a-4c in a present Example, about the
transducer of the polygonal prism which combined four sheets or more of electro-mechanical
transducer elements Also have similar features. [Effects of the Invention] As described above,
according to the present invention, an acoustic resonance circuit is formed by at least one of the
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mechanical vibration planes of the electro-mechanical transducer, and the structural portion of
the electro-mechanical transducer and the acoustic resonance circuit By sharing the structure
part, it is possible to provide a low frequency, high efficiency and light weight transmitter /
receiver wave.
[0002]
Brief description of the drawings
[0003]
M4l is a perspective view of an embodiment of the present invention, FIG. 2 is a plan view, FIG. 3
is an explanatory view showing the distribution of internal sound pressure and velocity, and FIG.
4 is an explanatory view showing the vertical directivity 5 is a perspective view of a conventional
sonar transducer, FIG. 6 is a side view of an electro-mechanical transducer used in the
conventional sonar transducer, and FIG. 7 is a conventional sonar transducer Explanatory
drawing which shows sound pressure and speed distribution in the resonance pipe ¦ tube used
for the wave device, FIG. 8 is explanatory drawing which shows the same vertical directivity. 1, 5:
transducers 2a to 2c, 7: diaphragms 3a to 3c, 8: piezoelectric plates 4a to 4c, 9: electricmechanical conversion elements 10a, 10b, lla. Llb: Lead wire agent Patent attorney Kihei
Watanabe
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