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JPH06269079

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
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DESCRIPTION JPH06269079
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
electroacoustic transducer for converting an electrical signal and an acoustic signal in a
transducer for detecting and communicating an object by transmitting and receiving an
ultrasonic signal in water. Related to
[0002]
2. Description of the Related Art Heretofore, in a transducer that performs object detection,
communication, etc. by transmitting and receiving ultrasonic signals in water, piezoelectric is
used as an electroacoustic transducer to convert the electrical signal and acoustic signal. Many
porcelain vibrators have been used.
[0003]
This piezoelectric ceramic vibrator is obtained by forming an electrode on a pair of opposing
surfaces after press molding and sintering, applying a high DC voltage between the electrodes to
polarize, and applying an electrical signal to the electrode Function as an electro-acoustic
transducer by exciting mechanical vibration to emit sound waves in the sound wave propagation
medium and exciting mechanical vibration by sound waves incident from the medium to output
an electrical signal from the electrode .
[0004]
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1
As a typical element for performing electroacoustic conversion in a transducer that transmits and
receives ultrasonic signals in water, conventionally, a cylindrical piezoelectric ceramic vibrator as
shown in FIG. 7 or an angle as shown in FIG. A columnar piezoelectric ceramic vibrator is used.
In each of the conventional vibrators, a pair of electrodes 6a and 6b are formed on the surface of
the piezoelectric ceramic sintered body 5, and a DC high voltage is applied between the
electrodes 6a and 6b for polarization processing. Ru.
[0005]
In addition, when the vibrator formed in this manner is used as an electroacoustic transducer,
generally, the signal cables 4a and 4b are connected to the respective electrodes 6a and 6b. It
can not be used underwater as it is.
That is, in this electroacoustic transducer, the electrodes 6a and 6b are always exposed on the
surface of the vibrator, and general water and seawater as the use environment have
conductivity, so this vibration is generated. When the child is immersed in water as it is, the
electrodes 6a and 6b are electrically shorted to be unusable.
[0006]
For this reason, in this type of electro-acoustic transducer, as shown in FIG. 9, the rubber-like
elastic body 8 having good sound wave permeability, the vibrator 7 and a supporting part for
supporting the vibrator 7 The whole of 9a and 9b is molded so as to prevent an electrical short
between the electrodes of the vibrator 7 in water. Separately from this, as shown in FIG. 10, the
vibrator 7 is installed in a watertight case 10 made of a metal case or the like by a pair of
supporting parts 9c, and the transmitting and receiving wave front of this vibrator 7 There is also
a method of making a watertight structure by closely contacting the acoustic window 11.
[0007]
However, as these conventional methods all require the watertight structure for the vibrator 7 as
described above, many parts for a large processing time and a watertight mechanism are
required. In addition, in order to obtain the characteristics expected as a transducer, there is a
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2
problem that much effort is spent on the boundary condition management of the portion that
transmits and receives the sound wave.
[0008]
The present invention has been made in view of the above-mentioned point, and its object is to
reduce the processing time and parts for providing a watertight structure, and to prevent the
deterioration of the characteristics of the transducer caused by the application of the watertight
structure. An electro-acoustic transducer that can
[0009]
SUMMARY OF THE INVENTION According to the present invention, an electrode plate made of a
metal plate or the like is embedded between unsintered and flexible piezoelectric sheets and
integrally sintered. After bonding, these are interposed on the surface of the piezoelectric sheet
to form an electrode so as to face the electrode plate, and polarization and drive are performed
by this electrode and the electrode plate inside the piezoelectric sheet. An electroacoustic
transducer is obtained.
[0010]
According to the present invention, after an electrode plate made of a metal plate or the like is
sandwiched between unsintered and flexible piezoelectric sheets and integrally sintered, Since an
electrode is formed on the surface so as to face the electrode plate, an electrical short circuit in
water between the electrode and the electrode plate inside the piezoelectric sheet is avoided.
[0011]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present
invention will be described in detail below with reference to the drawings.
However, in order to avoid complication of the description, the disclosure of the configuration,
operation and the like of the range which can be clearly recalled from the description of the
present embodiment will be omitted or simplified.
[0012]
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3
FIGS. 1 and 2 show a first embodiment of the present invention, in which the electro-acoustic
transducer has two piezoelectric sheets 1a, 1a, as shown in FIG. 1 and its back side in FIG. The
electrode plate 2 is sandwiched between 1b, and is formed into a flat plate shape and sintered.
In the piezoelectric sheet 1a of the present embodiment, a hole 1c processed before the sintering
is formed.
Moreover, each electrode 3a, 3b is respectively formed in the surface (both surfaces of the
piezoelectric material 1) of each piezoelectric material sheet 1a, 1b after the sintering.
[0013]
Here, in the electrode 3a formed on the piezoelectric sheet 1a, in order to ensure insulation with
the internal electrode plate 2, a portion corresponding to the hole 1c formed in the piezoelectric
sheet 1a has a constant width. A hole 3c of a size that forms a portion without an electrode is
provided.
The piezoelectric body 1 connects the internal electrode plate 2 and the signal cable at the hole
1c of the piezoelectric sheet 1a, and applies a high DC voltage between the electrode plate 2 and
the electrodes 3a and 3b. By performing polarization processing, it functions as a flat
electroacoustic transducer.
[0014]
As shown in FIG. 3, this electroacoustic transducer bends one piezoelectric sheet into two,
sandwiches the electrode plate 2 between the piezoelectric sheets, and shapes and sinters the
piezoelectric body 1. May be formed.
[0015]
FIG. 4 shows a second embodiment of the present invention, in which the electro-acoustic
transducer is formed into a cylindrical shape by squeezing the two electrode plates 2 between
the two piezoelectric sheets 1a and 1b. It is configured by molding and sintering.
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In the piezoelectric sheet 1a of the present embodiment, two holes 1c which are processed
before sintering are formed according to the position of each electrode plate 2. Further, on the
respective surfaces of the respective piezoelectric sheets 1a and 1b, that is, on the inner
peripheral surface and the outer peripheral surface of the cylindrically formed piezoelectric
member 1, respective electrodes 3a and 3b are formed over the entire circumference. Be done.
[0016]
Here, in the same manner as in the first embodiment, the electrodes 3a formed on the inner
peripheral surface of the piezoelectric body 1 are punched in the piezoelectric sheet 1a in order
to ensure insulation with the respective electrode plates 2 inside. At positions corresponding to
the respective holes 1c, respective holes 3c having a certain width and forming a portion without
electrodes are provided. The piezoelectric body 1 connects the two internal electrode plates 2
and the signal cable at two holes 1c of the piezoelectric sheet 1a, and the electrode plates 2 and
the respective electrodes 3a on the inner and outer peripheral surfaces , 3b, and polarization
processing is performed by applying a high DC voltage.
[0017]
The electro-acoustic transducer shown in each of the above-mentioned embodiments connects
the signal cable to each of the electrodes 3a, 3b provided on the surface of the piezoelectric body
1, so that the electrode plate 2 inside and the respective electrodes 3a, 3b on the surface An
alternating current signal is applied to emit a sound wave, or an external sound wave is received
to output an electric signal.
[0018]
The electro-acoustic transducer of this embodiment is characterized in that it can be used in air
as a normal speaker or microphone, and can be used without rubber molding the whole in water
or providing an acoustic window. .
[0019]
Compared to the conventional example shown in FIGS. 7 to 10, the electroacoustic transducer
according to the embodiment of the present invention, as shown in FIG. 5 and FIG. The
piezoelectric sheets 1a and 1b completely cover the portions other than the portion connecting
the signal cable 4a. Therefore, these piezoelectric sheets 1a and 1b are configured to function as
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a waterproof member of the electrode plate 2 .
[0020]
Thereby, in the electro-acoustic transducer of the present embodiment, the rubber mold 13 is
applied to the portion where the electrode plate 2 is exposed to the outside for connecting the
signal cable 4a, that is, the hole 1c of the piezoelectric sheet 1a. By waterproofing, only the
surface of the piezoelectric body 1 and the electrodes 3a and 3b are in contact with water.
Therefore, in the electro-acoustic transducer of this embodiment, the electrode plate 2 and the
electrodes 3a and 3b are not electrically short-circuited in water, so the function is performed in
water without extensive waterproofing. It can be done.
[0021]
Further, in the electro-acoustic transducer of the embodiment shown in FIGS. 5 and 6, the signal
cable 4b is not directly connected to the electrodes 3a and 3b, and the water in which the
electrodes 3a and 3b are immersed is electrically It is comprised so that it may utilize as a
propagation means of a signal.
That is, as shown in FIGS. 5 and 6, the end of the signal cable 4b to be connected to each of the
electrodes 3a and 3b in this embodiment is disposed to face a position separated from each of
the electrodes 3a and 3b. The cable watertight mold 14 is treated to prevent the entry of water
into the cable so that only the terminal 12 connected to the end of the signal cable 4b is in
contact with the water.
Here, as a matter of course, there is no problem in directly connecting the terminal of the signal
cable 4b to each of the electrodes 3a and 3b.
[0022]
Furthermore, in this embodiment, the suspension fitting 15 fixed to the piezoelectric body 1 and
the suspension ring 17 disposed on the signal cable are suspended by the suspension wire 16, so
that the end of the signal cable can be obtained. It is configured not to apply excessive load.
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[0023]
By the way, in the conventional electro-acoustic transducer, the boundary surface between the
vibrator 7 and the rubber-like elastic body 8 in FIG. 9 or the boundary surface between the
vibrator 7 and the acoustic window 11 in FIG. And the boundary conditions between the rubberlike elastic body 8 or the acoustic window 11 and the rubber-like elastic body 8 or the acoustic
window 11 and water, and the acoustic characteristics of the rubber-like elastic body 8 or the
acoustic window 11 as a transducer In particular, when an air layer is present between the
vibrator 7 and the rubber-like elastic body 8 or the acoustic window 11, the vibrator 7, the
rubber-like elastic body 8 or the acoustic window 11, the water and air Since the acoustic
impedance density of the above is largely different, the sound wave is reflected by the air layer,
which causes deterioration of transmission / reception sensitivity characteristics and disturbance
of directivity characteristics.
[0024]
On the other hand, in the electro-acoustic transducer of this embodiment shown in FIGS. 5 and 6,
the surface on which the electrodes 3a and 3b are provided is an ultrasonic wave transmission /
reception wavefront. Since it is in direct contact with water, which is a propagation medium of
the above, there is no boundary surface as described above, and a transducer with little variation
in acoustic characteristics can be obtained.
[0025]
According to the present invention, the function as a transducer can be obtained with almost no
need for secondary processing and a large waterproof member, and the transmitting and
receiving wave surface can be water, which is a propagation medium of ultrasonic waves. It is
possible to provide a stable transducer with less variation in acoustic characteristics in direct
contact.
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