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BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
low frequency band high power transmitter used for long distance sonar, marine resource
exploration and the like. (Conventional technology) Low-frequency ultrasonic waves in water
have less propagation loss compared to high-frequency waves and can reach far away, so lowfrequency ultrasonic waves in fields such as horn, marine resource exploration, ocean current
survey, etc. The use of ultrasound has many advantages. Conventionally, an electrodynamic
transducer and a piezoelectric transducer have been known as transmitters that emit highintensity ultrasonic waves in water. The electrokinetic transducer has a small surface generation
force that can cause large displacement. It is extremely difficult to obtain an Ij-type transducer at
low frequencies. In contrast, lead zirconate titanate-based piezoelectric magnetism is used as an
electroacoustic conversion material for piezoelectric transducers, and since the piezoelectric
ceramic has an acoustic impedance that is about 20 times or more larger than that of water, the
generated force is extremely large. Can not take the displacement necessary for medium
exclusion (acoustic radiation). In order to perform efficient acoustic radiation at low frequencies,
considering that the acoustic radiation impedance of the unit radiation area sb becomes
extremely small as the low frequency It is necessary to further expand the displacement of the
piezoelectric ceramic to perform acoustic radiation ◎ The following is a description of the
conventional piezoelectric transducer: A bolt-clamping rank transducer / transducer is a
transducer that transmits high-power ultrasonic waves in water. It is well known that it is actively
used in the frequency band of 3 kHz to several 10 kH However, when it is intended to operate at
a low frequency of this transducer k 3 kHz or less, it has a disadvantage that the weight size is
too large for practical use because it does not have a displacement expanding mechanism. . So,
for example, R, 8 * Woollett, Trendand Probrem in 5 onar Transducer Design as a transducer
that can be miniaturized at low frequencies.
IEEETransaonUltrasonicsEngineering。 As described in
pp. 116-124 (1963, 11), a sagittal transducer using bending vibration of a disk shown in FIG. 1,
or G, Brighaln 1 LGrasa, Present 8 tatus in Flexte-nsional Transducer Technology ' p + L ^ C0
ult * 8 oc, Am, Vo 1.68.
No, 4. pp, 1046-1052 (1980, 10), a bending and elongation transducer using an elliptical shell as
shown in FIG. 2 is known. 0 (Problems of the Prior Art) FIG. 1 A bending transducer using a
circular flat plate as shown is one using a circular bimorph oscillator as a wave transmitter as is
well known. In FIG. 1, c10 is a lead zirconate titanate piezoelectric ceramic plate, 11 is nickel,
stainless steel Etc., and a bimorph oscillator is composed of 1011 and the bimorph oscillator
itself is an acoustic radiator 0 or 12 is a cavity, 13 is a housing case. By bonding a large number
of segment ceramic plates to the metal plate 11 in a mosaic manner, it is impossible to obtain a
piezoelectric ceramic plate of an area. The bimorph vibrator is obtained at present 0 Therefore
excluded medium capacity as wave transmitter is not sufficient, Bruno) to Ibawa transmit 'not
suitable Hiroshi. Also, even if a large-area piezoelectric ceramic plate is obtained, the bimorph
oscillator has a large deflection compliance of the oscillator due to its structure, and a large
medium removal capability is not expected. When the piezoelectric ceramic columnar body 20 is
stretched and displaced in the long axis direction, the bending and elongation transducer using
the elliptical shell is uniform at several times the displacement of the columnar body 20 as
shown by the double arrows in the figure when the piezoelectric ceramic columnar body 20 is
displaced in the long axis direction. It is a transducer with a sort of displacement magnification
mechanism that shrinks (only a quarter of the parts are shown by arrows). Since the
displacement of the piezoelectric ceramic columnar body 20 is magnified several times and
ultrasonic waves are transmitted from the outer surface of the shell, and the structure as a shell
can obtain much greater rigidity than the bimorph disc, the transducer shown in FIG. However,
the performance of the flexible stretch transducer shown in FIG. 2 has the strong-shape
dependence of the elliptical shell. The short diameter a is smaller than the long voice. In other
words, a flat elliptical shell with a large eccentricity theoretically has good butterfly acoustic
consistency and good acoustic radiation efficiency. However, due to the following reasons, this
elliptical shell can not have an arbitrary shape ま ず First, the shape becomes flat but the stress is
concentrated in the vicinity of the large curvature portion 0 second In addition, it is necessary to
take the storage base of the piezoelectric ceramic columnar body and the electronic device. It is
impossible to make the ratio of the minor axis to the major axis a / b @ 0.3 or less practically
because of such a force. The displaced part is reed on the minor axis, and only 5 to 7 times
displacement is generated for the gin part さ ら に Furthermore, the transducer as shown in Fig.
2 has bidirectional or nearly neglected characteristics Although it is suitable as a ignoranceoriented transmitter because it has the above, it is impossible to apply it to a phased array
(Phased Array) or a conformal array (Conformal Array) with specific directivity. SUMMARY OF
THE INVENTION It is an object of the present invention to eliminate such drawbacks of the
conventional transducers and to provide a small size, high power characteristic transmitter in the
low frequency band. .
(Structure of the Invention) That is, according to the present invention, the active columnar body
capable of exciting longitudinal vibration and the non-active columnar body consisting of the
hinge portion and the base portion are arranged in parallel, and these ends are connected with
the lever through the hinge. A low frequency underwater ultrasonic wave transmitter is
characterized in that a convex shell or concave shell is formed at the end of the lever to further
expand the displacement of the lever. (Detailed Description of Configuration) The transmitter
according to the present invention will be described according to the following figures which are
busy solving various problems of the prior art by employing the above two-stage displacement
enlarging mechanism. FIG. 83 shows an example of a transmitter according to the present
invention using Compex She A / ((11 is a front view, (b) is a bottom view) of the transmitter
shown in FIG. The principle of operation will be described in detail. In the active columnar body
composed mainly of a piezoelectric ceramic ring, 31R, by applying a voltage, the longitudinal
vibration is excited in parallel with the active columnar body 31. It is arranged. Non-active
columns made of high mechanical strength materials such as high tensile strength steel from
hinges 33, 33 'and base 31' have considerable rigidity against longitudinal displacement and
deflection displacement Is designed to be flexible. When the active column is displaced by 図 1 as
shown by the double arrow in the figure, the lever 34.34 ′ rotates inward by an angle θ and an
enlarged displacement ξ occurs at one end P, P ′ of the lever. If the lever is made of a
sufficiently rigid material (eg high tensile stainless steel), the lever will move almost like a rigid
body, and the distance between the hinges 32, 33 or 32 ', 33' 12. Letting the distance tle
between the hinge 33 and the P or the hinge 33 'and the P', the geometrically enlarged
displacement 眞 is 161 眞 -1 lt l (11 @ eg 3 = 3 The displacement of the column is 3 times larger
than the displacement ξ1. In order to efficiently transmit to the lever 34.34 'the generated force
relating to the longitudinal vibration excited by the active columnar body, the inactive columnar
body acting as a fulcrum with the mouth 2 which is generated in PIA. As described above, it is
necessary to considerably increase the rigidity with respect to the longitudinal vibration. As an
example of a countermeasure for this, in FIG. 3, the base portion 31 'is thick. In addition, when
the lever 34.34 'is rotated by an angle 0, the hinge 32 that contacts the lever 32.
32<、33. The bending moment is generated at the portion 31.31 'of the columnar body,
and the bending moment is generated, and the magnitude of the bending moment is determined
by the hinge 32. 32 、33. 33 '+ 2) Smaller deflection compliance # greater * at the same
time post 31. 31' and hinge 32, 32 '. If the deflection compliance of the 33.33 'system is small,
the rotation of the small lever 34, 34' will be impeded. Thus, here hinge 32. 32 ', 33. 33',
longitudinal compliance is low and deflection compliance is preferably large hinges (e.g. flat
hinges). Furthermore, in pep'A, a displacement of only ξ 2 and a displacement effect of # 35 @
and a shape effect of the convex shell indicate that several times enlarged displacement is shown
in the double arrow of the figure. Because of this two-stage displacement amplification
mechanism, the transducer of the present invention 6 is given a very large displacement at the
acoustic radiation surface, and it is compact and excellent in acoustic radiation and capability. It
can be said that 0 denotes a small projection provided with a lever 34p 34 QC, which is effective
for improving the rigidity of the lever 0. Next, an example of the active columnar body used in
the wave transmitter of the present invention The active column will be described in detail with
reference to FIG. 4 shown in FIG. In FIG. 4, 4F is a piezoelectric ceramic ring, and adjacent
piezoelectric ceramic rings are connected such that the polarization directions are opposite to
each other and electrically connected in parallel. 42 is a bolt, 43 is a nut and works to apply a
static compressive stress to the piezoelectric ceramic ring 41. 0 The reason is that although the
piezoelectric ceramic has high mechanical strength against pressure, it is vulnerable to tension,
so excitation is The piezoelectric ceramic ring 41iC is sometimes used to prevent the generation
of tension. As a result, it is possible to drive several times the tension limit inherent to the
piezoelectric ceramic. In the active columnar body having such a structure, the directions of
polarization and electric field beck) / l / in all the piezoelectric ceramic rings 41 are uniformly in
phase or uniformly in antiphase with the kernel. Is able to stretch and shrink uniformly. As
another configuration using the convex shell of the present invention, as shown in FIG. 5, active
columnar body 31 and base 31 ', hinges 33, 33'I5. The low-frequency ultrasonic transducer can
also be configured by exchanging the arrangement position of the non-active columnar body that
consists of 0. Figure 5 (a) is a front view, and (b) is a bottom view. When the active column is
displaced by a weir, an enlarged displacement 柱状 appears at the point P, with the inactive
column as a supporting point.
Assuming that the distance tl between the hinges 32 and 3 and the distance between the hinge
32 and the point P are / and /. In this case, the geometrically enlarged displacement ξ will be.
For example, l, '= 21. If ', then a 3-fold magnified displacement appears at point P. Furthermore,
due to the shape effect of the convex shell, an enlarged displacement several times larger than
that of the light is given as indicated by the double arrow in the figure. Although the example of
the transmitter based on the present invention using the convex shell has been described above,
the ultrasonic transmitter using the concave shell 35 'as shown in FIGS. As shown by the double
arrows, it is obvious that the convex shell performs the same operation as the acoustic radiation
except that the phase is different by π. In FIG. 6 and FIG. 7, 31 is an active column, 31 'is a base
portion of the non-active column, 32.32' and 33.33 'are hinges and (Implementation)
The underwater ultrasonic wave transmitter using a convex type seal will be described with
reference to FIG. 8 as an embodiment of the present invention. The thickness of the transducer
using a convex type shell shown in FIG. 3 The main component is cork and synthetic rubber, in
order to prevent the 6 acoustic coupling with the transducer and housing case housed in the
approximately 9-p '& pR housing case 81 and to prevent the rotational movement of the lever.
The acoustic shell and the convex shell 35 for acoustic radiation are arranged on the side and
bottom of the lever to perform 0 acoustic radiation. The radius of curvature of the convex shell
35 is larger than the outer diameter. In this case, the planar shape is 50m × 40aa. The shape is
not limited to a rectangle. 0 and thickness is 1.5 to 2.0 譚. Lever 34, 34 ', hinges 32, 32', 3333
'and so on. Convex shell 35 shape is all made of high tensile steel 共振 Resonant frequency in air
of the prototype truss absorber is 850 Hz, mass ti 52 Kf ・ The displacement of active columnar
rest displacement is 12 times in the central part of convex shell Is obtained. Here, when this
transducer is driven with high power in a 90-shape by means of a piezoelectric ceramic ring as
shown in FIG. 4 as a technical column, the sound pressure at a point 1 m away from the acoustic
radiation end 'is measured. If we try to realize a high-power transmitter with a resonance
frequency of 850 Hz using the conventional bolt-clamped Langevin oscillator with the
characteristics shown in Fig. 0, the mass is theoretically more than 300. ) Can not be put to
practical use.
(Effect of the Invention) As an excellent effect of the underwater low frequency wave transmitter
according to the present invention as described above, the displacement magnification of n times
(n> 1) at the acoustic radiation end with respect to the displacement of the active columnar body
Therefore, the mass of the acoustical radiation end is converted to an active columnar material,
n2 times, and a lightweight, low-frequency transceiver is obtained. That is, it can be said that the
transducer of the present invention is a transducer capable of simultaneously achieving low
frequency, downsizing, and high efficiency simultaneously. In the wave transmitter of the present
invention, needless to say, it is possible to use a high performance magnetostrictive material
containing a rare earth element as a component of the piezoelectric ceramic as the active
columnar body.
Brief description of the drawings
Fig. 1 shows a conventional bending transducer. Fig. 2 shows a conventional bending and
elongation transducer, and Figs. 3 (a) and 3 (b) show the feeding of the present invention for a
convex type shell. Fig. 4 shows an example of a wave device, Fig. 4 shows an active column used
in the wave transmitter of the present invention, and Fig. 5 shows another example of the
structure of the wave transmitter of the present invention using a convex shell. FIG. 6, FIG. 6 and
FIG. 7 show an example of a transmitter according to the present invention using a concave shell,
FIG. 8 shows an embodiment of a transmitter according to the present invention, and FIG. These
are the output sound pressure characteristic figures in one Example of the wave transmitter of
this invention.
9 busy, 10 is a piezoelectric ceramic plate, 11 is a metal plate, 12 is a cavity: 13 is a housing
case. 20 is a piezoelectric ceramic columnar body, 21 is an elliptic shell, 31 is an active columnar
body, 3f is a base portion of the non-active columnar body, 32, 32 ', 33, 33' are hinges, 34.34'a
//-1a5 Is a convex type shell, 35 'ti concave type shell, 36 is a small projection, 41 is a
piezoelectric ceramic ring, 42 is a bolt, 43 is a screw, 81 is a housing case, 82 is an acoustic deca,
a ring material, arrows are polarized Direction, double arrows indicate the direction of
displacement Lower Ding \\ Agent Attorney Attorney Uchihara, 乎 4 Figure 43 414 141 III 41 #
4236 31 亭 8 Dd 7/9 J Day p Procedure Amendment 2, Spontaneous Title of the Invention
Relationship to the low frequency underwater ultrasonic wave transmitter 3 ° correction case
Applicant: Shiba 5-cho, Minato-ku, Tokyo Eye 33 No. 1 (423) NEC Corporation-Representative
Sekimoto Tadahiro 4, Agent Shiba 5-Chome 5-8 7 Minato-ku, Tokyo Sumitomo Mita Building
(Contact Information NEC Corporation Patent Department) 5, Target of Correction Correct the
contents of the description in the second column of the detailed description of the invention of
the invention in the second column on the second page of the specification, and correct it as
"arrival". ♂) Statement #! On the 2nd page, line 14 corrects that F is F . (Refer to page 3
of the specification, line 18 and "bent type transducer" as "bent type transducer".