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DESCRIPTION JPS59190795

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DESCRIPTION JPS59190795
[0001]
The present invention relates to low frequency transducers of several hundred 1 + z or less. In
recent years, a low-frequency sound source that can obtain a sound pressure level of 180 dB re 1
μPa or more in the 1oonz to several hundreds Hz (7) frequency range is strongly desired as an
ultrafast distance transducer as well as underwater exploration and propagation research using
sound waves. There is. As is well known, these low frequency sound sources are used by being
submerged in the sea of about 1000 m or more from the viewpoint of far-field sound
propagation. Conventionally, an electrodynamic or variable reluctance type has been proposed as
a low frequency sound source drive method, but in order to operate in the deep sea of about
1000 m, it is essential to use a liquid filled or pressure balanced transducer configuration.
Therefore, there is a disadvantage that it is extremely difficult to obtain the required sound
pressure because the driving force is too small. On the other hand, a piezoelectric transducer can
obtain sufficient driving force, but it has been difficult in the past to obtain the speed of the
radiation end face corresponding to the sound pressure of 180 dBre 1 μPa. The present
invention uses a pressure balance type He Imho I t z resonator to operate stably even in deep
seas, and further provides a displacement magnifying mechanism to eliminate the drawback that
the speed of the radiation end face of the conventional piezoelectric transducer is small. This is
done to realize a piston vibration type low frequency transducer capable of obtaining a large
sound pressure. The drawings will be described below. FIG. 1 shows an example of a
conventional piston vibration type low frequency piezoelectric transducer. In FIG. 1, reference
numeral 10 denotes a piezoelectric ceramic portion, which is a bolted Langevin vibrator as well
known in the art, in which the polarization directions of adjacent cylindrical piezoelectric ceramic
vibrators are opposite to each other and mechanically cascaded. Electrically connected in
parallel, and also used in a pre-mechanical compressive stressed condition with bolts. Reference
numeral 11 denotes a connector% 12 a piste 741 body plate, 13 denotes an enclosure portion of
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a 61 mh 01 iz resonator, and 14 denotes a cavity portion of a He Imholtz resonator. The
equivalent circuit representation for the electro-mechanical vibration system of the transformer
shown in FIG. 1 J is shown in FIG. In FIG. 2, Cd is damping capacity, human force coefficient, Cc is
compliance of piezoelectric ceramic part, Cs1 is compliance of connector, mx is mass of piston
rigid plate, vt, Fx is velocity at the end face of piston radiation, Show power. The resonant
frequency f @@ of the transducer shown in FIG. 1 is given by: ## EQU1 ## when driven in
connection with the amplifier.
From the equation (1), it is understood that the compliance C6 of the connector is increased and
the frequency is reduced as the mass m1 of the piston is increased. However, the piston radiation
for obtaining sufficient sound pressure to increase Ccl and mx The vibration velocity of the
piezoelectric ceramic portion is required to be considerably larger than Vx, which is one for the
velocity v1 of the end face. That is, in order to lower the frequency, it is necessary to set the
vibration speed of the piezoelectric ceramic part with a considerable margin to the vibration
speed of the piston part, but to increase the vibration speed of the piezoelectric ceramic part
comes from above the material It is obvious that there are certain limitations and energy
efficiency is worse with conventional transducers. It is an object of the present invention to
provide a high efficiency piezoelectric low frequency transducer which eliminates these
drawbacks. That is, the present invention is a piezoelectric low frequency transducer
characterized in that a piston movement type piezoelectric transducer having a Hermholtz
resonator is provided with a displacement enlarging mechanism comprising a lever and a hinge.
An example of the low frequency transducer of the present invention is shown in FIG. In FIG. 3,
the same piezoelectric ceramic part as in FIG. 1, 21 is a hinge, 22 is a lever, レ バ ー is a
connector, 24 is a piston rigid plate, stone is an enclosure part of i (elmholtz resonator, 2b is The
cavity portion of the He 1 m h o 1 @ z resonator is shown, and the displacement of the
piezoelectric ceramic portion 20 is intended to be enlarged by this principle. In detailing the
operation W of the transducer of FIG. 3 and the filling, the configuration of the main part is
shown in FIG. In FIG. 4, '1 H' l * 'I is the description of the hinge 21 in FIG. 3 divided into parts,
and IL1 and IL indicate the lengths of parts of the lever 22. In addition, IL4 indicates a
connective pathway. In order to describe the operating characteristics of FIG. 4 in detail, the
equivalent circuit display of FIG. 4 is shown in FIG. In FIG. 5, cd is a damping capacity, A is a
force coefficient, co is a compliance of the piezoelectric ceramic portion, m 3 is an equivalent
mass of the piezoelectric ceramic portion, CL 8. Cも。 CJ, hinges J1. ! , J, vertical compliance, CB
is the hinge J, the fixed part from the compliance, C is the hinge JL yo, between b8's (deflection
compliance of the D lever, IL inertia moment of the lever 'Cbz hinge' 1 Composite deflection
compliance consisting of p GeJLs and ceramic part, CLb *: deflection compliance of lever CIL, ξ,) CJt4: new flange of connector 14, rnx: mass of piston rigid plate 〇 5th From the figure it can
be designed that the mass m1 of the piston plate can be made sufficiently small, and it can be
considered almost negligible with regard to the characteristics of the transducer.
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Also, Cbl has negligible effect compared to C0. The compliances that work effectively for the low
frequency of the transducers are: compliances CJ, Cn, CJ, CJ, CI, bx which are placed in parallel in
the circuit. CLtly "a", and these cooperate with each other to lower the frequency. Also, the
velocity of the ceramic end face is about 116. / IL, it will be doubled. That is, in the transducer
using the displacement expanding mechanism of the present invention and the He1mholtz
resonator, sufficient vibration displacement can be obtained in the piston bowl plate
simultaneously with lowering the frequency, and a high-power and small-size low-frequency
sound source in deep sea Can be realized. Next, as an example of the low frequency sound source
of the present invention, a transducer having the structure of FIG. 3 will be described. l (e1
mholtz resonator δ has a resonant frequency at 250 Hz and is cylindrical. The piston rigid plate
U is circular and is located inside the He1mholtz resonator with a slight gap. There are three
driving piezoelectric ceramic parts, which are separated by 120, and a connecting rod is in
contact with a bending node of a piston disc eliminator. The resonance frequency for the
mechanical vibration system is set to around 300 Hz. When the maximum sound pressure at a
position irn away from the piston plate of this transducer was measured, the characteristics
shown by the solid line in FIG. 6 were obtained. On the other hand, the similar maximum sound
pressure characteristics of the low frequency sound source having the conventional structure of
FIG. The maximum length of any sound source is less than 1 rn, and the input power is also the
same. Therefore, according to the present invention, a low frequency, high power transducer can
be realized.
[0002]
Brief description of the drawings
[0003]
FIG. 1 is a structural view of a conventional piston vibration low frequency piezoelectric
transducer, FIG. 2 is an equivalent circuit diagram regarding an electromechanical vibration
system of the transducer shown in FIG. 1, and FIG. Fig. 4 is a structural view of a low frequency
piezoelectric transducer, Fig. 4 is a diagram showing the main part of the transducer of Fig. 3 to
Fig. 5 is an equivalent circuit diagram of the transducer of Fig. 4; Is the maximum sound pressure
characteristic of the transducer.
In the figure, 10.20 is a piezoelectric ceramic portion, 11 ° is a connector, 12.24 is a piston
rigid plate, 13.25 is a He1mholtz resonator enclosure, 14, 26 are He1mholtz resonator cavity
portions, 21 is a hinge, 22 is a lever, J-1, also, JI- 諺 is a hinge, JL4 is a connector, cd is a braking
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capacity, A is a force coefficient, CC, ”St, C4-CJ *, C4, CB, CLbt, Cbx, CLbt C4a: compliance, □□:
lever inertia moment, ml: mass of piston rigid plate, mff1: equivalent mass of piezoelectric
ceramic part, Vx: vibration velocity, and Fl: force. Oh 1 Figure / j 10 // Oh? Layer o 3 Flash z 5 zti
it 2275 Bile! 1,4□: 1
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