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BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
electroacoustic transducer for use in water, and more particularly to a transmitter suitable for the
delivery of sound waves at depth. [Prior Art] A conventional Langevin type transmitter has a
front mass 1 as shown in FIG. Piezoelectric element The vibrator consisting of the rear mass 6 is
connected to the case 5 by the support rubber 4 to maintain the water tightness, and the
vibration of the vibrator is transmitted to the case using the low stiffness of the support rubber
from the case It is common to prevent secondary acoustic radiation and to keep the amount of
damping of the transducer small. However, in this configuration, as the depth increases, the
support rubber is compressed, and as the stiffness increases, there is a disadvantage that the
resonance frequency and the electrical impedance largely change. OBJECTS OF THE INVENTION
The object of the present invention is to provide an electroacoustic transducer which is used
between shallow depths and depths to which high water pressure is applied, resulting in little
change in the electroacoustic characteristics as a transmitter. It is to do. [Summary of the
invention] In the wave transmitter shown in FIG. 1 described above, the vibration amplitude is
maximum at the front mass side of the front mass and at the rear mass side at the rear mass back
surface. There is a so-called vibration node, and in the first place, to avoid supporting at a point
where the vibration amplitude is large, to support at a part that becomes a vibration node,
secondly, the front mass side from the vibration node It is characterized in that it is completely
exposed to the sea and made of a material having no characteristic change due to water pressure.
Sixth, it is characterized by having a structure without unnecessary acoustic radiation.
[Embodiment of the Invention] Hereinafter, an embodiment of the present invention Will be
described with reference to FIG. In FIG. 2, 11 is a metal front mass with one side (acoustic
radiation surface side) of a hollow cylinder closed, 12 is a piezoelectric element, 15 is a rear
mass, 14 is a front mass 11, and piezoelectric element 12. The front mass 11 and the support
plate 14 are joined by welding or the like, and the support plate 14, the piezoelectric element 12
and the rear mass 13 are bonded. The numeral 15 is a watertight case for preventing water from
directly contacting the piezoelectric element 12 and the rear mass color, and the numeral 16 is a
cable for electrically connecting with the piezoelectric element. The piezoelectric element 12. The
system of the rear mass 13 is driven, whereby the front mass 11 having a quarter wavelength
length is excited to emit a sound wave. When the front mass 11 is made of a solid metal, along
with the vibration in the longitudinal direction, the Poisson's ratio of the material causes radial
vibration of the cylinder perpendicular to this, and the radiation of this antiphase reduces the
conversion efficiency. According to this embodiment, the amplitude in the radial direction
becomes weak, and there is an effect that the characteristic change with depth is eliminated
Effect of the Invention According to the present invention, there is almost no distortion due to
water pressure, no change in stay, etc. in the part in contact with water, and almost no
unnecessary acoustic radiation from parts other than the acoustic emission surface of the front
mass. As it can be done, the change of the electroacoustic characteristic is extremely small from
shallow depth to deep degree, and it is effective to maintain high electroacoustic conversion
Brief description of the drawings
FIG. 1 is a partial sectional view seen from the side of a general Langevin-type transducer, and
FIG. 2 is a partial sectional view seen from the side of a transmitter according to an embodiment
of the present invention.
11 иии Front mass 12 и и и Piezoelectric element 13 и и и Rear mass 14 и и и Support plate 15 и и и Case
16 иии Cable exposed II Ц 1 first? Figure
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