close

Вход

Забыли?

вход по аккаунту

?

DESCRIPTION JP2001141808

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JP2001141808
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
ultrasonic transducer used in an underwater ultrasonic device such as a fish finder.
[0002]
2. Description of the Related Art FIG. 9 is a block diagram of a conventional fish finder. In the
figure, 1 is an ultrasonic transducer mounted on the bottom of the ship to transmit and receive
ultrasonic waves, 2 is a transformer circuit for applying a weighted voltage to the transducers of
the transducer 1 and 3 is an operation of the transducer 1 4 is a transmission circuit for giving a
transmission signal to the transmitter / receiver 1 via the trap circuit 3, and 5 is an echo signal
from the seabed which the transmitter / receiver 1 has received. A receiver circuit received via
the trap circuit 3, a control unit 6 for performing calculation and control based on a received
signal from the receiver circuit 5, and a display unit 7 for displaying data such as fish school and
water depth.
[0003]
FIG. 10 shows an example of the configuration of the ultrasonic transducer 1, where (a) is a
perspective view and (b) is a bottom view. As shown in FIG. 10A, a large number of piezoelectric
vibrators A are arranged on the lower surface of the transducer 1. The piezoelectric vibrator A is
13-04-2019
1
made of a cylindrical electrostrictive element such as a piezoelectric ceramic. When a high
frequency or low frequency voltage is applied to the piezoelectric vibrator A, the element vibrates
and an ultrasonic wave is transmitted. Reference numeral 8 denotes a cable for supplying power
to the piezoelectric vibrator A.
[0004]
The piezoelectric vibrators A are arranged concentrically as shown in FIG. 10B, and in this
example, are arranged over four circumferences. From the center to the periphery, four
piezoelectric vibrators A1 on the first circumference, ten piezoelectric vibrators A2 on the second
circumference, and sixteen piezoelectric vibrators A3 on the third circumference, the fourth
Twenty-two piezoelectric vibrators A4 are arranged around the circumference.
[0005]
FIG. 11 shows the directivity characteristics of the ultrasonic transducer 1 as described above.
The horizontal axis represents the angle with respect to the sound axis which is the center of
directivity, and the vertical axis represents the signal level (dB). As can be seen from the figure, in
addition to the original detection signal S1 near the sound axis, a side lobe signal S2 is generated
in the peripheral area of the sound axis. When such a side lobe signal S2 is present, the echo by
this signal is also received simultaneously, so the echo by the detection signal S1 and the echo by
the side lobe signal S2 are mixed, and the control unit 6 (FIG. 9) The fish signal can not be clearly
identified, and the fish image displayed on the display 7 also becomes blurred. It is empirically
confirmed that this tendency appears notably when the level difference between the side lobe
signal S2 and the detection signal S1 becomes 20 dB or less.
[0006]
Therefore, in order to avoid this, the applied voltage of the piezoelectric vibrators A1 to A4
arranged on each circumference is weighted according to a predetermined function such as a
Chebyshev function, as shown in FIG. It is a conventional practice to suppress the signal S2 as
much as possible and improve the directivity characteristics.
[0007]
13-04-2019
2
FIG. 13 shows an example of a circuit for this purpose.
As illustrated, the piezoelectric vibrators A1 to A4 on the respective circumferences of the
transducer 1 are connected in parallel, and transformers T1 to T4 are provided for the respective
vibrators A1 to A4. These transformers T1 to T4 constitute the transformer circuit 2 of FIG. The
primary side of the transformers T1 to T4 is connected to the power supply V, and one end of
each parallel circuit of the corresponding piezoelectric vibrators A1 to A4 is connected to the
middle tap on the secondary side. Then, by appropriately selecting the intermediate tap position
of each of the transformers T1 to T4, the voltage ratio of the transformers T1 to T4 to the
piezoelectric vibrators A1 to A4 is A1 = 1, A2 = 0.88, A3 = 0. A voltage is supplied so that .66, A4
= 0.58. The voltage ratio is a weighting according to a Chebyshev function, and by weighting the
voltage applied to the piezoelectric vibrators A1 to A4, the side lobe signal becomes -20 dB or
less with respect to the detection signal, and the directivity characteristic is shown in FIG. It is
well known that it improves like 12.
[0008]
In addition to the Chebyshev function, for example, there is a method of using a Bessel function,
etc. In the Japanese Examined Patent Publication No. 3-23874 proposed by the present
applicant, the Bessel function is determined using a transformer as described above A transducer
is disclosed that applies a voltage to the transducer.
[0009]
However, in the above prior art, since the transformer is used to weight the voltage applied to the
vibrator, there is a problem that the number of electric parts increases and the cost becomes
high. was there.
In addition, there is also a problem that space for the transformer is required, which becomes an
obstacle in downsizing the device.
[0010]
Therefore, the present invention is intended to improve the directivity characteristics without
using a transformer, and it is an object of the present invention to provide a transducer which
can be realized at low cost and in a small size by reducing electric parts.
13-04-2019
3
[0011]
SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, according to
the present invention, the voltage applied to each transducer changes from the central portion of
the transducer toward the peripheral portion. A predetermined number of transducers are
connected in series.
[0012]
By doing this, a voltage divided according to the impedance is applied to the serially connected
vibrators, so by appropriately selecting the number of vibrators connected in series, The applied
voltage can be varied as going from the center to the periphery of the transducer, and can be set,
for example, to a value substantially conforming to the weighting defined by the Chebyshev
function.
That is, in the present invention, since the applied voltage can be weighted in a predetermined
manner by the vibrator itself, the directivity can be improved without the need for a transformer.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be
described below with reference to the drawings.
FIG. 1 is a block diagram of a fish finder according to an embodiment of the present invention. In
the figure, 1 is an ultrasonic transducer mounted on the bottom of the ship to transmit and
receive ultrasonic waves, 3 is a trap circuit for switching the operation of the transducer 1
between the transmitting side and the receiving side, and 4 is a trap circuit for transmitting
signals. 3 is a transmitter circuit to be supplied to the transmitter / receiver 1. 5 is a receiver
circuit for receiving an echo signal from the seabed received by the transmitter / receiver 1 via
the trap circuit 3. 6 is a receiver signal from the receiver circuit 5. A control unit that performs
calculation and control based on the display unit 7 is a display unit that displays data such as a
fish school and water depth. As can be seen by comparing FIG. 1 with FIG. 9, the transformer
circuit 2 of FIG. 9 does not exist in FIG.
13-04-2019
4
[0014]
FIG. 2 is a bottom view showing an example of the ultrasonic transducer 1, corresponding to FIG.
10 (b). The appearance of the transducer 1 is the same as that shown in FIG. In FIG. 2, the
piezoelectric vibrators A1 to A4 are formed of cylindrical electrostrictive elements such as
piezoelectric ceramics, and are arranged concentrically over four rounds as in FIG. 10 (b). From
the central portion toward the peripheral portion, four piezoelectric vibrators A1 are arranged on
the first circumference and ten piezoelectric vibrators A2 are arranged on the second
circumference, which are the same as in the case of FIG. 10 (b) However, it differs from the case
of FIG. 10B in that the number of piezoelectric vibrators A3 of the third circumference is 12 and
the number of piezoelectric vibrators A4 of the fourth circumference is 21. The reason will be
clarified later.
[0015]
FIG. 3 is a diagram for explaining the basic principle of the present invention. Assuming that the
impedance of one piezoelectric vibrator 10 is Z and the applied voltage is V, when two vibrators
10 are connected in series, the impedance of the series circuit is 2Z and the voltage applied to
each vibrator 10 is V It will be / 2. When three vibrators 10 are connected in series, the
impedance of the series circuit is 3Z, and the voltage applied to each vibrator 10 is V / 3. That is,
by connecting the piezoelectric vibrators 10 in series, the value of the voltage applied to each
vibrator 10 can be controlled. The present invention focuses on this point and weights the
applied voltage of the piezoelectric vibrator.
[0016]
FIG. 4 is a circuit diagram showing the first embodiment of the present invention, and shows a
state in which each of the piezoelectric vibrators A1 to A4 shown in FIG. 2 is connected. In the
figure, four piezoelectric vibrators A1 of the first circumference are connected in series, and the
series body 11 is connected between the lines of the voltage V. Assuming that the individual
vibrators of the piezoelectric vibrators A1 to A4 all have the same impedance, and the impedance
of one vibrator is Z, the combined impedance of the series body 11 is 4Z.
[0017]
13-04-2019
5
Further, ten piezoelectric vibrators A2 on the second circumference are divided into two groups
of five each, and five vibrators are connected in series in each group, and each series body 12 is
between the lines of voltage V Connected The combined impedance of series body 12 is 5Z.
[0018]
In addition, 12 piezoelectric vibrators A3 on the third circumference are divided into two groups
of six each, and six vibrators are connected in series in each group, and each series body 13 is
between the lines of voltage V Connected The combined impedance of series body 13 is 6Z.
[0019]
Furthermore, 21 piezoelectric vibrators A4 on the fourth circumference are divided into three
groups of seven each, and seven vibrators in each group are connected in series, and each series
body 14 is connected between the lines of voltage V Be done. The combined impedance of series
body 14 is 7Z.
[0020]
In this manner, when viewed from the terminal to which voltage V is applied, series members 11,
12, 13, 14 in which a predetermined number of piezoelectric vibrators A1, A2, A3, A4 are
connected in series are connected in parallel. It will be.
[0021]
Here, the values of the voltages applied to the piezoelectric vibrators A1, A2, A3 and A4 are
compared as follows.
The voltage applied to each of the first piezoelectric vibrator A1 is V / 4, the voltage applied to
each of the second piezoelectric vibrator A2 is V / 5, and the voltage applied to each of the third
piezoelectric vibrator A3 is The voltage applied to each of the piezoelectric vibrators A4 of V / 4
and the fourth circumference is V / 7. Therefore, when the voltage ratio of the piezoelectric
vibrator A1 of the first circumference is 1, the voltage ratio of the piezoelectric vibrator A2 of the
13-04-2019
6
second circumference is V / 5 ÷ V / 4 = 0.8. Similarly, the voltage ratio of the third piezoelectric
vibrator A3 is V / 6 ÷ V / 4 = 0.67, and the voltage ratio of the fourth piezoelectric vibrator A4
is V / 7 ÷ V / 4 = 0. It becomes .57. That is, weighting is performed so that the voltage applied to
the transducers A1 to A4 changes as going from the central part of the transducer 1 to the
peripheral part.
[0022]
The voltage ratio thus determined and the voltage ratio according to the Chebyshev function in
FIG. 13 are as shown in the following table.
[0023]
As seen from the above table, the voltage ratio according to the present invention realized by the
circuit of FIG. 4 has almost no difference compared to the voltage ratio calculated from the
Chebyshev function, and closely approximates the value defined by the Chebyshev function. The
value is
Therefore, even without using a transformer as in the prior art, weighting of the applied voltage
substantially conforming to the Chebyshev function can be realized only by devising the
connection of the piezoelectric vibrator, thereby suppressing the side lobe signal and improving
the directivity characteristic be able to. FIG. 5 is a diagram showing the directivity characteristic
of the transducer 1 using the circuit of FIG. 4, in which the side lobe signal S2 is -20 dB or less
with respect to the detection signal S1, and the directivity characteristic is improved. I
understand.
[0024]
FIG. 6 is a circuit diagram showing a second embodiment of the present invention. Here, the
piezoelectric vibrator A1 of the first circumference and the piezoelectric vibrator A2 of the
second circumference are connected in parallel one by one, and the piezoelectric vibrator A3 of
the third circumference and the fourth circumference The two piezoelectric vibrators A4
connected in series are connected in parallel. Therefore, the voltage applied to the piezoelectric
vibrators A1 and A2 is V for the first and second circumferences, and the voltage is applied to the
piezoelectric vibrators A3 and A4 for the third and fourth circumferences. The voltage is V / 2.
That is, assuming that the voltage ratio of the first circumference and the second circumference
13-04-2019
7
is 1, the voltage ratio of the third circumference and the fourth circumference is 0.5, and the
voltage ratio of the third circumference and the fourth circumference near the peripheral part is
Weighting is performed so as to be smaller than the voltage ratio of the first cycle and the second
cycle.
[0025]
FIG. 7 is a diagram showing the directivity characteristic of the transducer 1 configured by the
circuit of FIG. Also in this case, the side lobe signal S2 becomes -20 dB or less with respect to the
detection signal S1 by performing the above-mentioned weighting, and it can be seen that the
directivity characteristic is improved.
[0026]
FIG. 8 is a circuit diagram showing a third embodiment of the present invention. B is a
rectangular piezoelectric vibrator made of an electrostrictive element such as a piezoelectric
ceramic, and a plurality of B are linearly arranged. The piezoelectric vibrators B3 and B4 closer
to the central portion are independently connected between the lines of the voltage V, and the
piezoelectric vibrators B1 and B2 closer to the peripheral portion are connected in series two by
two. Connected between the lines of. Similarly, piezoelectric vibrators B5 and B6 closer to the
peripheral portion, which are connected in series two by two, are connected between the lines of
the voltage V.
[0027]
Therefore, the voltage applied to each of the piezoelectric vibrators B3 and B4 in the central
portion is V, and the piezoelectric vibrators B1, B2, B5, and B6 in the peripheral portion are
applied to the respective vibrators. The voltage is V / 2. That is, when the voltage ratio of the
vibrator in the central portion is 1, the voltage ratio in the peripheral portion is 0.5, and as in the
case of FIG. 6, the voltage ratio of the vibrator closer to the peripheral portion is vibration near
the central portion The weighting is made to be smaller than the voltage ratio of the child. As a
result, as described above, the side lobe signal can be suppressed to improve the directivity.
[0028]
13-04-2019
8
The above is the case where ultrasonic waves are transmitted from the ultrasonic transducer 1.
However, even when the ultrasonic transducer 1 receives an echo signal, the directivity
characteristic of the transmitter 1 is not limited to FIG. Similar to 7, the outputs according to the
respective weightings are taken out from the receiving circuit 5.
[0029]
In the embodiment described above, a vibrator made of an electrostrictive element such as a
piezoelectric ceramic has been exemplified as a vibrator, but instead, a vibrator made of a
magnetostrictive element such as a ferrite vibrator is used. It can also be done.
In this case, a coil is added to convert the applied voltage into a magnetic field.
[0030]
Further, in the above embodiment, the Chebyshev function has been exemplified as a function for
weighting the voltage applied to the vibrator. However, a Bessel function may be used.
Furthermore, it is also possible to apply window functions, such as a Hamming window and a
Hanning window, and the degree of change in weighting differs depending on each function.
[0031]
In addition, although the arrangement of the transducers is four in FIG. 2, this is also an example,
and the number may be three, five, or more. Further, the number of vibrators is not limited to the
case of FIG. 2 and can be selected arbitrarily.
[0032]
Furthermore, the present invention can be widely applied to underwater ultrasonic instruments
such as sounding instruments, tidal meters and sonars besides fish finders.
[0033]
13-04-2019
9
According to the present invention, since the applied voltage can be weighted by the vibrator
itself, an expensive transformer is not required to improve the directivity characteristics, and the
cost can be significantly reduced.
In addition, there is an advantage that space can be saved by eliminating the need for a
transformer, and the apparatus can be miniaturized.
13-04-2019
10
Документ
Категория
Без категории
Просмотров
0
Размер файла
19 Кб
Теги
description, jp2001141808
1/--страниц
Пожаловаться на содержимое документа