JPH01174099

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DESCRIPTION JPH01174099
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
electroacoustic transducer, and more particularly to an electroacoustic transducer suitable for
use as a transducer for measuring the incident direction of sound waves in water. PRIOR ART
FIG. 4 is a perspective view of a conventional electroacoustic transducer. In the figure, (3 (6a, 6b)
is a cylindrical piezoelectric body,? (7a to 7d) are inner electrodes, 8 (8a to 8d) are outer
electrodes, 9 (9a, 91) are transformers with center taps, and 10 (IOa, 101) are individual
transducers. As described above, the conventional electroacoustic transducer divides the inner
surface electrode 7 of the cylindrical piezoelectric body 6 into four equal parts along the
circumferential direction and divides the plurality of vibrators 10 a and 10 b polarized in the
same direction. The division direction was aligned and the product N was arranged. Further,
divided electrodes in the same direction of the respective vibrators 10a and 10b are connected in
parallel. That is, an output between two opposing divided electrodes 7a, 7c and 7e, 7g and two
divided electrodes 7b orthogonal to this. 7dと7f、? The outputs between h and h are
respectively connected to transformers 9a and 9b with separate center taps. Then, two
orthogonal die ball signals output from each of the transformers 9a and 91, a combination of two
center taps, and two outer surface electrodes 8a. 81) to extract the omni signal output from
between and the incident direction of the sound wave was measured from these. That is, in the
die ball signal and the omni signal in this case, the primary longitudinal vibration along the
circumference of the cylindrical piezoelectric body (two nodes around the circle) and the zeroth
longitudinal vibration (nodes on the circumference) The signal generated by the so-called
respiratory oscillations) was separated and extracted by the choice of the connection of the split
electrodes. By the way, when the frequency of the sound wave to be measured is a wide band, socalled flexural resonance may occur in which an integer number of transverse waves are
generated in the circumferential direction of the cylindrical piezoelectric body. Then, in the
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conventional electro-acoustic transducer, when this flexural resonance occurs, the output signal
by the flexural resonance is added to the die ball signal, and as a result of disturbing the
directivity characteristic of the die ball, the orientation accuracy is significantly deteriorated C.
[Problems to be solved ,? X] The above-mentioned conventional electro-acoustic transducer has a
problem that the directional accuracy is significantly deteriorated because the output signal by
the deflection collision is added to the die ball signal at the frequency of the flexural resonance
and the directivity characteristic of the die ball is disturbed. there were. The present invention
has been made in view of the above problems, and aims to provide a high-precision electroacoustic transducer with a small azimuthal error over a wide band by improving the die ball
directivity characteristics at a flexural resonance frequency.
[Solution to the Problem] In order to achieve the above object, the electroacoustic transducer
according to the present invention comprises a first external electrode pair in the X direction and
a first external electrode pair which is opposite to the outer surface of the cylindrical
piezoelectric body in the X direction. And a first vibrator having an inner electrode which is not
divided into four on the inner surface, and is opposed to the inner surface of the cylindrical
piezoelectric body in the X direction. A second vibrator having a first inner electrode pair divided
into four and a second inner electrode pair divided into four corresponding to the X direction and
having an outer electrode not divided into four on the outer surface; A first center-tapped
transformer for differentially connecting the output of the first inner surface electrode pair of the
second vibrator to the output of the first outer surface electrode pair of the first vibrator; Against
the output of the second outer surface electrode pair of the vibrator of the second A structure
city and a second with center tap transformer to connect the output of the differential of the
inner surface electrode pairs. Then, an orthogonal die ball signal is output from the secondary
side output of the first and second transformers with center taps, and the center taps are
combined, an inner surface electrode of the first imaging motor, and the second An omni signal is
output from between the external surface electrode of the image pickup moving member and the
one. The present invention will be described in detail with reference to the following drawings. In
the present embodiment, in order to simplify the description, the number of transducers is two.
FIG. 1 is a perspective view of an electro-acoustic transducer according to an embodiment of the
present invention, and FIGS. 2 (a) to 2 (c) are diagrams showing directivity characteristics of
orthogonal die ball signals. The figure which shows the directional characteristic sharpened to
the X direction, the figure (b) is a figure which shows the directional characteristic blunted to the
X direction, and the figure (c) is a figure which shows a normal directional characteristic. In the
same figure, la and lb are cylindrical piezoelectric bodies respectively, and the cylindrical
piezoelectric body 1a is provided with inner electrodes 2a to 2d and an outer surface electrode
3a divided into four equal parts, and another cylindrical piezoelectric body 1b is provided. The
outer surface electrodes 3b to 3e and the inner surface electrode 2e which are divided into four
equal parts are installed, and respectively constitute the vibrators 4a and 4b. And these two
vibrators 4a. 4b is stacked and arranged on the-axis, but at this time, the positional relationship is
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such that the directions of the respective divided electrodes coincide with each other. In addition,
the opposed inner electrode 2a of the vibrator 4a. 2c and external electrodes 3b and 3d facing in
the same direction of the vibrator 4a are differentially connected to the primary side of the
transformer 4a. This is to compensate for phase inversion of each output signal by making the
extraction electrodes different.
Then, a die ball signal in the X direction is output to the secondary side of the transformer 4a.
Similarly, a die ball signal in the X direction is output to the secondary side of the transformer
4b. By the way, the connection viewed from the primary side center taps of the transformers 4a
and 4b has an effect of shorting the counter electrodes 5 connected to the primary side.
Therefore, the center tap for drawing out the divided electrodes on the inner surface and the
center tap for drawing out the divided electrodes on the outer surface are put together, and the
inner and outer electrodes on the non-divided side are collectively connected. You can get a
signal. Here, the cylindrical piezoelectric body 1a corresponds to a second vibrator, and the
external electrodes 3b and 3d correspond to a first divided external electrode pair that is
opposed in the X direction, and the external electrodes 3c and 3e are X The inner electrode 2 e
corresponds to an inner electrode not divided into four while corresponding to a second outer
electrode pair divided into four corresponding to the direction. Similarly, the cylindrical
piezoelectric member 1b corresponds to a first imaging electrode, and the internal electrodes 2a
and 2c correspond to a first divided internal electrode pair divided in four corresponding to the X
direction, and the internal electrode 2b, 2 d corresponds to a second divided second inner
surface electrode pair corresponding to the X direction, and the outer surface electrode 2 e
corresponds to an outer surface electrode not divided into four. Now, at the frequency at which
the flexural resonance occurs, the signal of the flexural resonance is added to the die ball signal
as described above. And as a result of characterizing the directional characteristics of the die ball
at this time, the inner surface electrode. The die ball directivity characteristic obtained from the
above becomes dull as Vx in FIG. 2 (a), and the die ball directivity characteristic obtained from
the external electrode becomes dull as vy in FIG. 2 (1). However, in the electro-acoustic
transducer of the present embodiment having the above configuration, these two types of
distorted die ball directivity characteristics are added together. As a result, the strain components
of each other are averaged, so that it can be improved to a normal die ball as Vx and Vy shown in
FIG. 2 (c). Although the above description is based on the X direction, the same change as in the
X direction is shown in the X direction. Thus, in the present embodiment, the inside of the
cylindrical piezoelectric body '/), i? A first vibrator group having an inner surface electrode
divided into four equal parts to H and an outer surface electrode divided and not divided, a
fourth vibrator in the same direction as the first vibrator on the inner and outer surfaces of the
cylindrical piezoelectric body An electro-acoustic system comprising a plurality of outer
electrodes divided into two parts and a second vibrator group having an inner electrode not
divided, and aligning the directions of the divided electrodes of each vibrator group and
laminating a plurality of sets coaxially In the converter /-, the first output of the first electrode
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group of the first transducer group and the first set of outer surface electrode outputs of the
second transducer group opposed in the same direction have a neutral point. Of the second set of
internal electrode outputs and the second group of transducers opposed in the same direction.
The set of outer surface electrode outputs is a second transformer differential with a neutral
point.
Next, FIG. 3 is a perspective view of an electroacoustic transducer according to another
embodiment of the present invention. In the electro-acoustic transducer of the same figure, first,
the electrodes of the inner and outer surfaces of one cylindrical piezoelectric body 1c are divided
into upper and lower three equal parts in the axial direction (2f to 21 and 2J, and 3f to 3g and 3j)
. Then, next, the upper side divides the inner surface electrode, and the lower side divides the
outer surface electrode into four equal parts in the same direction. That is, in the present
embodiment, the inner and outer electrodes are divided into upper and lower three equal parts
along the axial direction, and one of the upper and lower inner electrode is divided into four
equal parts, and the other outer electrode is the above inner surface. A vibrator divided into four
equal parts in the same direction as the divided electrodes is used. By adopting such a
configuration, in the present embodiment, the object of the present invention can be achieved
with only one cylindrical piezoelectric body. Also in this embodiment, the same transformer and
connection as in the previous embodiment are required, but they are omitted in the figure.
Further, the present invention is not limited to the above embodiments, but includes various
modifications within the scope of the present invention. For example, in the above-described
embodiment, the transducers are stacked and arranged on a single axis, but may be arranged
otherwise. [Effects of the Invention] As described above, according to the present invention, a
cylindrical piezoelectric body is provided with an electrode whose inner surface side is divided
into four equal parts and an electrode whose outer surface side is divided into four equal parts,
and a die ball drawn from the outer surface electrode By combining and connecting the
extraction electrodes differentially with respect to the signal and the die ball signal extracted
from the inner surface electrode, there is an effect that it is possible to provide a highly accurate
electro-acoustic transducer with a small azimuthal error over a wide band. That is, the phase
inversion is compensated by adding and averaging the output of the outer surface electrode and
the output of the inner surface electrode, and the die-ball directivity characteristic is distorted in
the opposite direction, so that the die-ball directivity characteristic at the flexural resonance
frequency can be improved. It is because it can.
[0002]
Brief description of the drawings
[0003]
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FIG. 1 is a block diagram of an electroacoustic transducer according to an embodiment of the
present invention, FIG. 2 is a diagram showing directivity characteristics of orthogonal die ball
signals, and FIG. 3 is an electroacoustic transducer according to another embodiment of the
present invention FIG. 4 is a perspective view of a conventional electroacoustic transducer.
1 2 cylindrical piezoelectric body 2: inner surface electrode 3 2 outer surface electrode 4:
vibrator 5: transformer with center tap
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