JP2011166288

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DESCRIPTION JP2011166288
PROBLEM TO BE SOLVED: To provide an inexpensive electro-acoustic transducer in which
production of an electrode can be easily carried out by screen printing, which requires less time
and effort for polishing. SOLUTION: A cylindrical piezoelectric vibrator 1 and two balanced
transformers are provided. The cylindrical piezoelectric vibrator 1 is polarized in the direction of
the central axis of the cylinder and has an entire surface electrode 2 on the lower end surface of
the cylinder. , And four divided electrodes 3A, 3B, 3C, 3D formed on the upper end surface of the
cylinder so as to be divided into four in the circumferential direction, and two divided electrodes
3A and 3C opposed to each other with respect to the central axis , And 3B and 3D as a pair of
electrode pairs, respectively. Two pairs of electrode pairs are configured, and one electrode pair
is connected to each end of the primary side of the balanced transformer, and the secondary of
the balanced transformer Obtain a signal having dipole directivity in a direction in which two
divided electrodes constituting an electrode pair connected to the primary side of each balanced
transformer from the side face each other, and the primary sides of two balanced transformers A
non-directional signal is obtained from between the terminal to which all the middle points are
connected and the entire electrode 2. [Selected figure] Figure 1
Electro-acoustic transducer
[0001]
The present invention relates to an electroacoustic transducer for a sonar, and more particularly
to an electroacoustic transducer used in a sonar system for detecting the distance and direction
of a target.
[0002]
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The sonar system is a device that uses underwater sound waves to search, detect, and range
objects in ships and water.
As disclosed in Patent Document 1, an electroacoustic transducer used in a conventional sonar
system uses a cylindrical piezoelectric vibrator polarized in the radial direction, and the outer
circumferential surface and the inner circumferential surface thereof There is an electro-acoustic
transducer configured by forming an electrode obtained by dividing each of the faces into four,
and connecting the divided electrodes to a balanced transformer.
[0003]
The electro-acoustic transducer with this structure divides both the electrodes on the inner and
outer peripheral surfaces of the piezoelectric vibrator, so it takes time and effort to manufacture
and is expensive. , Various attempts have been made. For example, Patent Document 2 proposes
an electroacoustic transducer having a structure in which the outer peripheral surface of a
cylindrical piezoelectric vibrator polarized in the radial direction is an entire surface electrode
and only the inner peripheral surface is an electrode of four divisions.
[0004]
FIG. 5 is a perspective view of a conventional piezoelectric vibrator having the above-described
structure, and FIG. 6 is a circuit diagram showing a configuration of a conventional
electroacoustic transducer using this piezoelectric vibrator. As shown in FIGS. 5 and 6, in the
electroacoustic transducer of this structure, the two divided electrodes 13A, 13B, 13C, 13D of the
inner peripheral surface of the cylindrical piezoelectric vibrator 11 are opposed to each other.
Connected to both ends of the primary side of the two balanced transformers 14A and 14B, and
from the secondary side of the balanced transformer, the two electrodes connected to the
primary side have dipole directivity in the opposite direction A signal, ie, a signal of X direction
dipole directivity and a signal of Y direction dipole directivity, is obtained, and it is nothing from
between the terminal to which the middle point of the primary side of balanced transformers
14A and 14B is connected and the entire surface electrode 12 of the outer peripheral surface A
signal having directivity can be obtained.
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[0005]
Japanese Patent Publication No. 63-57999 Japanese Patent Publication No. 5-62706
[0006]
However, in the case of the conventional electroacoustic transducer as described above, since the
piezoelectric vibrator has a cylindrical shape, it takes time and effort to divide and manufacture
the electrode on the inner peripheral surface, and the polarization direction has a diameter
Because it is a direction, in order to obtain uniform sensitivity, the thickness between the outer
peripheral surface and the inner peripheral surface needs to be uniform, so that it takes time and
effort for polishing and an extra material for polishing is required. And there was a problem that
it becomes expensive.
[0007]
Therefore, an object of the present invention is to solve the problems of the prior art described
above, to provide an inexpensive electroacoustic transducer in which the preparation of the
electrode can be easily carried out and the labor for polishing is reduced.
[0008]
In order to solve the above problems, an electroacoustic transducer according to the present
invention is an electroacoustic transducer using a cylindrical piezoelectric vibrator and n (n is an
integer) balanced transformers, and the piezoelectric vibrator described above Is polarized in the
direction of the central axis, and has an entire surface electrode formed on almost the entire
surface of the upper end surface or the lower end surface, and is divided into 2n pieces in the
circumferential direction on the other end surface The n divided electrode pairs each having two
n divided electrodes opposed to each other with respect to the central axis of the 2 n divided
electrodes constitute one set of electrode pairs. An electrode pair of the n electrode pairs is
connected to both ends of the primary side of the balanced transformer, and the primary side of
the balanced transformer is connected from the secondary side of the balanced transformer. Two
split electrodes that make up an electrode pair connected to the side have dipole directivity in the
opposite direction Give a signal, characterized in that to obtain a signal having an omnidirectional
from between the n balanced transformer primary side of the midpoint and all the connected
terminals entire electrode.
[0009]
That is, the piezoelectric vibrator of the electroacoustic transducer according to the present
invention is polarized not in the cylindrical radial direction but in the central axis direction as in
the prior art, and the electrodes have a cylindrical shape instead of the cylindrical outer
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peripheral surface or inner peripheral surface. The lateral effect vibration of the cylindrical
piezoelectric vibrator is utilized.
[0010]
As described above, in the present invention, since the portion where the electrode of the
cylindrical piezoelectric vibrator is to be formed is the upper and lower end surfaces rather than
the inner and outer peripheral surfaces which are troublesome to manufacture, the electrode is
easily manufactured by screen printing. As a result, an inexpensive electroacoustic transducer
can be obtained, which requires less time and effort for polishing.
[0011]
The perspective view of the piezoelectric vibrator used for the electroacoustic transducer of one
embodiment by the present invention.
FIG. 1 is a circuit diagram showing a configuration of an electroacoustic transducer according to
an embodiment of the present invention.
It is a chart figure of the directivity obtained with the electroacoustic transducer of one
embodiment by the present invention, and a figure showing the result of having simulated the X
direction dipole directivity.
It is a chart figure of the directivity obtained with the electroacoustic transducer of one
embodiment by the present invention, and a figure showing the result of having simulated the Y
direction dipole directivity.
The perspective view of the conventional piezoelectric vibrator.
The circuit diagram which shows the structure of the conventional electroacoustic transducer.
[0012]
Hereinafter, embodiments of the electroacoustic transducer according to the present invention
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will be described with reference to the drawings.
[0013]
FIG. 1 is a perspective view of a piezoelectric vibrator used in an electroacoustic transducer
according to an embodiment of the present invention, and FIG. 2 is a circuit diagram showing a
configuration of the electroacoustic transducer according to the present embodiment.
As shown in FIGS. 1 and 2, the electroacoustic transducer according to the present embodiment
has a cylindrical piezoelectric vibrator 1 and two balanced transformers 4A and 4B, and the
cylindrical piezoelectric vibrator 1 is a cylinder. There are four electrodes which are polarized in
the direction of the central axis and have the entire surface electrode 2 formed on almost the
entire surface of the lower end surface of the cylinder, and the upper end surface of the cylinder
is divided into four in the circumferential direction. Two divided electrodes 3A, 3B, 3C, 3D, two
divided electrodes 3A and 3C, and 3B and 3D opposed to each other with respect to the central
axis of the four divided electrodes as one set of electrode pair Of the two primary pairs of
balanced transformers 4A and 4B are connected to each other at one end of the primary side of
the balanced transformers 4A and 4B, and the secondary sides of the balanced transformers 4A
and 4B are connected. Constitute an electrode pair connected from the terminals 5A, 5B and 6A,
6B to the primary side of each balanced transformer Obtain a signal with dipole directivity in the
direction in which the two split electrodes face each other, and turn nondirectionality from
between the terminal 7A where all the midpoints on the primary side of the two balanced
transformers are connected to the entire electrode 2 I am getting the signal that I have.
[0014]
The details of the configuration and operation of the electroacoustic transducer according to the
present embodiment will be described below.
[0015]
As shown in FIG. 1, as a specific example of the shape of the cylindrical piezoelectric vibrator 1, a
cylindrical piezoelectric body having an outer diameter of 200 mm, an inner diameter of 177
mm, and a height of 20 mm is used, and divided electrodes 3A, 3B, 3C on the upper end surface.
A 2 mm gap may be made between adjacent 3D electrodes, and the entire electrode 2 may be
polarized with the negative electrode and the divided electrodes 3A, 3B, 3C, and 3D as the
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positive electrode.
Piezoelectric ceramics such as PZT can be used as the piezoelectric body.
[0016]
As shown in FIG. 2, among the divided electrodes 3A, 3B, 3C and 3D of the cylindrical
piezoelectric vibrator 1 of FIG. 1, the opposing electrodes 3A and 3C are used as primary
terminals of the first balanced transformer 4A. Connecting the secondary side terminals 5A and
5B of the first balanced transformer 4A as dipole directional terminals in the X direction, and
connecting 3B and 3D to the primary side terminal of the second balanced transformer 4B, The
secondary side terminals 6A and 6B of the second balanced transformer 4B become dipole
directional terminals in the Y direction.
[0017]
The terminals 7A drawn out by short-circuiting the primary side middle point of the first
balanced transformer 4A and the second balanced transformer 4B and the terminals 7B pulled
out from the entire surface electrode 2 of the cylindrical piezoelectric vibrator 1 are not directed.
It becomes sex terminal.
[0018]
When the cylindrical piezoelectric vibrator 1 shown in FIG. 1 receives a sound wave, the portion
of the piezoelectric vibrator in the lower range of the opposing divided electrodes has a ringshaped expansion vibration due to a sound pressure difference between the inside and the
outside of the cylinder, We receive plane vibration at the same time.
Since the polarization direction of the cylindrical piezoelectric vibrator 1 is the same as the
height direction, signals of the spreading vibration of the annular ring with the entire electrode 2
as a middle point are applied to the facing divided electrodes 3A and 3C or 3B and 3D. In the
same phase, the signal of the plane vibration appears in the opposite phase.
[0019]
The divided electrodes 3A and 3C or 3B and 3D are connected in series as shown in FIG. 2 so
that the polarization directions are reversed, and when the signal is taken out through the
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balanced transformer 4A or 4B, the secondary side terminal The signals of the spreading
vibration of the in-phase annular ring on the primary side are canceled out to 5A and 5B, or 6A
and 6B, and only signals of plane vibrations of opposite phase are outputted.
[0020]
As a result, from the secondary terminals 5A and 5B of the balanced transformer 4A, a signal
having dipole directivity in the direction in which the divided electrodes 3A and 3C oppose each
other, that is, the X direction is obtained, and the second order of the balanced transformer 4B.
From the side terminals 6A and 6B, a signal having dipole directivity in the direction in which the
divided electrodes 3B and 3D are opposed, that is, the Y direction is obtained.
[0021]
The signal between the terminal 7A connecting the middle points of the balanced transformers
4A and 4B and the terminal 7B of the full surface electrode 2 cancels out the signal of the plane
vibration which is in antiphase between the opposing divided electrodes 3A and 3C or 3B and
3D. In this case, only the signal of the spread vibration of the in-phase ring is output, and a
nondirectional signal is obtained.
[0022]
3 and 4 are charts of directivity obtained by the electroacoustic transducer according to the
embodiment of the present invention.
FIG. 3 shows the result of simulating the X direction dipole directivity obtained from the
secondary side terminals 5A and 5B when a 5.5 kHz transmission signal is sent to the cylindrical
piezoelectric vibrator having the shape of the above-mentioned specific example. Similarly, FIG. 4
shows the result of simulating the Y direction dipole directivity obtained from the secondary side
terminals 6A and 6B.
It is understood that dipole directivity in the X and Y directions can be obtained as in the prior
art.
[0023]
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As described above, in the cylindrical piezoelectric vibrator of the electroacoustic transducer
according to the present embodiment, the divided electrodes are formed on the end face of the
cylinder, and therefore, they can be easily manufactured by screen printing.
Further, since the polarization direction is the direction of the central axis, ie, the height
direction, the height thereof may be made uniform, and polishing for making the thickness
between the outer peripheral surface and the inner peripheral surface uniform as in the prior art.
This eliminates the need for time and effort, and can be manufactured at a lower cost than in the
past.
[0024]
It goes without saying that the present invention is not limited to the above embodiment, and
design changes can be made according to the purpose and application.
For example, the number 2n of divided electrodes of the cylindrical piezoelectric vibrator may be
2 or 6 or more, and the number of balanced transformers can be set according to the number.
Also, the shape, material, etc. of the piezoelectric vibrator can be designed according to the
purpose.
[0025]
DESCRIPTION OF SYMBOLS 1, 11 Cylindrical piezoelectric vibrator 2, 12 whole surface electrode
3A, 3B, 3C, 3D, 13A, 13B, 13C, 13D (splitting) electrode 4A, 4B, 14A, 14B Balanced type
transformer 5A, 5B, 6A, 6B Secondary side terminal 7A, 7B terminal
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