JPS6351638B2 - - Google Patents

Description

Detailed Description of the Invention This invention uses a sound insulating material between the piezoelectric parts of a piezoelectric cable to separate the piezoelectric cable into an inner layer and an outer layer, and connects the output terminals of these inner and outer layers with opposite polarities. By extracting the differential voltage between the output generated on the inner layer side and the output generated on the outer layer side, we have created a piezoelectric cable that can obtain only the output voltage based on underwater sound even when acceleration is applied to this piezoelectric cable. This invention relates to an underwater receiver used in the wave receiving section.

Some ships that navigate on water or at sea are equipped with underwater receivers that convert underwater sound waves into electrical signals that can be extracted.

FIG. 1 is a partially cutaway side view showing an example of an underwater receiver installed in such a ship. In this figure, 1 is a case of this underwater receiver 2, and inside this case 1 are piezoelectric cables 3, 3...
is provided. Each piezoelectric cable 3, 3... receives sound waves applied to the case 1 via an insulating liquid (such as insulating oil) 4 filled in the case 1, as shown in Fig. 2. These piezoelectric cables 3, 3... each have a central conductor 5.
, an outer conductor 6, and a piezoelectric rubber (or other piezoelectric material) 7 provided between the center conductor 5 and the outer conductor 6, and is added to these piezoelectric cables 3, 3... The preamplifier 8 in the case 1 is supplied with a voltage corresponding to the fluctuation of the pressure in the case 1. The preamplifier 8 is connected to the piezoelectric cable 3,
3..., and the output of this preamplifier 8 is supplied to a signal processing device (not shown) via a cable 9 provided at one end of the case 1.

In this way, in the conventional underwater receiver 2, the sound waves received by the case 1 are transmitted to the piezoelectric cables 3, 3, . . . via the insulating liquid 4,
Here, this signal is converted into a corresponding electric signal, and then amplified by the amplifier 8 and supplied to the subsequent circuit.

By the way, in such an underwater receiver 2, when measuring underwater sound, vibrations caused by wind waves, water currents, or the shaking of the ship itself are transmitted to the receiver via the cable, and this vibration is transmitted to the receiver at the sensing part. The acceleration output voltage is transmitted to certain piezoelectric cables 3, 3, . . ., and these piezoelectric cables 3, 3, .

In view of the above points, this invention extracts only the output voltage based on underwater sound even when acceleration due to unnecessary vibrations is transmitted to the underwater receiver due to wind waves, water currents, or the movement of the ship itself. The purpose of this invention is to provide an underwater receiver capable of

In the underwater receiver according to the present invention, the first piezoelectric body portion and the second piezoelectric body portion are arranged concentrically, and the first piezoelectric body portion and the second piezoelectric body portion are arranged concentrically. A sound insulating layer is provided in between, and a piezoelectric cable is formed by connecting the first piezoelectric body part and the second piezoelectric body part in series with opposite polarity to convert underwater sound waves into electrical signals and extract them. It is characterized by the fact that

The present invention will be described below based on an embodiment shown in the drawings.

FIG. 3 is a sectional view showing an embodiment of a piezoelectric cable used in an underwater receiver according to the present invention, and FIG. 4 is a circuit diagram showing an example of the connection between the inner layer and the outer layer of this piezoelectric cable. be. In FIG. 3, 10 is a piezoelectric cable, and this piezoelectric cable 10 is composed of an outer layer 11, an inner layer 12, and a sound insulating layer 13 formed between them, which are arranged concentrically.

Below, these outer layer part 11, inner layer part 12, sound insulation layer 1
3 will be explained in order.

First, the outer layer portion 11 includes a cylindrical outer conductor 14,
It is composed of a cylindrical first intermediate conductor 15 arranged concentrically with respect to the outer conductor 14, and a first piezoelectric rubber 16 provided between them, and is shown in FIG. As shown, the outer conductor 14 of this outer layer portion 11 is connected to one output terminal 17,
Moreover, the first intermediate conductor 15 is connected to the intermediate terminal 18 .

In addition, the inner layer section 12 includes a second intermediate conductor 19 having a cylindrical shape similar to the outer layer section 11, a center conductor 20 disposed on the central axis of the second intermediate conductor 19, and a center conductor 20 disposed on the central axis of the second intermediate conductor 19. The center conductor 20 of this inner layer portion 12 is connected to the intermediate terminal 18, and the second intermediate conductor 19 is connected to the other output terminal 22. has been done.

The sound insulating layer 13 is made of a material containing a large amount of air, such as paper tape or cloth, or is made of air itself, and the underwater sound received by the piezoelectric cable 10 is absorbed by the sound insulating layer 13. The inner layer part 12 is blocked and is inside this sound insulation layer 13.
It has become difficult to transmit information to the public.

Next, the underwater sound detection operation of this piezoelectric cable 10 having the above configuration will be explained.

First, when only underwater sound is received by the piezoelectric cable 10, this underwater sound is cut off by the sound insulating layer 13 and is not supplied to the inner layer 12 located inside the sound insulating layer 13. In this case, only the outer layer portion 11 generates an output voltage Es corresponding to the sound wave, which is outputted from output terminals 17 and 22 and supplied to a signal processing circuit (not shown). Next, in this state, when vibrations caused by the shaking of the ship, wind and waves, etc. are applied to the piezoelectric cable 10 along with the underwater sound, this vibration causes the piezoelectric rubbers 16 and 21 to generate a voltage (acceleration voltage) due to vibration acceleration.
occurs. Since underwater sound is cut by the sound insulating layer 13 as in the case described above, in this case, the outer layer 11
is the voltage Es + Eα that is the sum of the output voltage Es due to underwater sound and the voltage (acceleration voltage) Eα due to vibration acceleration
The inner layer section 12 outputs an acceleration voltage -Eα due only to the vibration acceleration, and as a result, the output terminals 17,
22 to these voltages Es+Eα and acceleration voltage −
The voltage Es that is the sum of Eα, that is, the same voltage Es as when there is only underwater sound, is output.

In this way, in this voltage cable 10,
By blocking sound waves with the sound insulation layer 13,
Since a differential voltage is generated by this sound wave between the outer layer part 11 and the inner layer part 12 and taken out, the acceleration voltage generated by vibrations other than underwater sound is canceled out in the piezoelectric cable 10. It can be made zero.

Next, a specific example of an underwater receiver using a piezoelectric cable having such a configuration will be described.

FIG. 5 is a partially cutaway side view showing a first embodiment of the underwater receiver according to the present invention. In this figure, 24 is an outer cylindrical case (for example, a cylindrical case made of rubber, vinyl, etc.) that forms the outer casing of this underwater receiver 25, and a tension member (made of fiber) is provided on the inner surface of this cylindrical case 24. Cylindrical woven fabric) 26
is provided, and one end of the outer cylindrical part 27 consisting of the cylindrical case 24 and the tension member 26 is closed with a stopper part 30 by tightening bands 28 and 29, and the other end is closed by tightening bands 31 and 32. The inner cylinder part 35 is disposed within a sealed space 34 that is closed by the cable connection part 33 and thus formed. The inner cylindrical part 35 includes a cylindrical case (for example, a vinyl hose) 36 having a large number of holes penetrating the outside and inside thereof, and this cylindrical case 36.
, short cylindrical cushion rubbers 39a to 39d disposed within the cylindrical case 36, and a preamplifier 40 held by these cushion rubbers 39a to 39d, respectively. and piezoelectric cables 41b to 41d obtained by winding the piezoelectric cable 10 into a coil shape. The cylindrical case 36 of the cylindrical portion 35 is held by short cylindrical cushion rubbers 42a to 42d provided so as to come into contact with the inner surface of the outer cylindrical portion 27, and one stopper of the inner cylindrical portion 35 The metal fitting 37 is pulled to the left (to the left in the figure) by the elastic rope 43 provided at the cable connection part 33, and
The other stopper 38 is pulled to the right by an elastic rope 44 attached to the stopper part 30, and tension is applied to the inner cylinder part 35 in the axial direction. Further, the inside of the outer cylindrical portion 27 is filled with insulating liquid OIL such as insulating oil, so that the sound waves received by the underwater receiver 25 are easily transmitted to the piezoelectric cables 41b to 41d. There is.

When this underwater receiver 25 is suspended or towed, both underwater sound and vibrations transmitted via the cable 47 due to the movement of the ship, wind waves, etc. pass through the outer cylinder 27 to the cushion rubber 4.
2b to 42d, the cylindrical case 36 and the cushion rubbers 39b to 39d arranged to correspond to the cushion rubbers 42b to 42d, respectively, and the insulating liquid OIL are transmitted to the piezoelectric cables 41b to 41b through the respective acoustic media. . This results in
The outer layer and inner layer of each of these piezoelectric cables 41b to 41d generate voltage signals corresponding to these acoustic signals and mechanical vibrations, cancel out the acceleration output voltage caused by the mechanical vibrations, and output only the acoustic output voltage. The preamplifier 40 is connected to the preamplifier 40 via signal lines 45b to 45d, respectively.
The signal amplified here is supplied to the signal line 46,
The signals are sequentially supplied to a signal processing device (not shown) via a cable 47.

As described above, in this embodiment, the piezoelectric cables 41b to 41d are arranged at predetermined intervals, and the underwater sound and vibration noise received by the outer cylinder part 27 are detected by the piezoelectric cable 41b. By detecting the phase difference between the signals output from 41b to 41d, the direction of underwater sound can be determined from the detection result. Furthermore, in this case,
Each of the piezoelectric cables 41b to 41d is wound into a coil to increase the mounting density at each point, increase the capacitance, and improve the S/N (signal-to-noise) ratio.

Next, a second embodiment of the underwater receiver according to the present invention will be described with reference to FIG. In addition, in the underwater receiver 49 shown in this figure, since its both ends are the same as the underwater receiver 25 shown in FIG. Objects are given the same reference numerals.
In this figure, reference numeral 50 denotes short cylindrical porous cushion rubber (such as sponge) 51b to 51 provided so as to come into contact with the inner surface of the outer cylindrical portion 27.
This inner cylinder part 50 is an inner cylinder part held by the inner cylinder case 36 having a large number of holes, and a cylindrical porous cushion rubber provided so as to come into contact with the inner surface of the inner cylinder case 36. 52, 52...
...and these porous cushion rubbers 52, 52
A linear piezoelectric cable 5 held by...
It consists of 3.

In this way, in this underwater receiver 49,
Since the piezoelectric cable 53 formed in a straight line is used, if cable vibrations caused by underwater sound, vibration of the ship, or wind waves reach the outer cylindrical part 27, these will be absorbed by the insulating liquid filled in the outer cylindrical part 27. The signal is transmitted by the OIL to the piezoelectric cable 53, where it is converted into a corresponding electrical signal and then supplied to a signal processing device via a preamplifier and a cable as shown in FIG.

FIG. 7 is a partially cutaway side view showing a third embodiment of the underwater receiver according to the present invention. Also in this figure, the same reference numerals are given to the parts corresponding to those in FIG. 5. In this figure, 55, 55
. . . are linear piezoelectric cables disposed inside the outer cylindrical portion 27, and each of these piezoelectric cables 55, 5
5... are held by cylindrical porous cushion rubbers 56, 56... that abut against the inner surface of the outer cylindrical portion 27.

In this way, in this underwater receiver 57,
Since a plurality of piezoelectric cables 55 formed in a straight line are bundled, the vibration of the outer cylinder part 27 is transmitted to each piezoelectric cable 55, 55 through the insulating liquid OIL impregnated with the porous cushion rubber 56, 56... …
...and convert it into multiple identical electrical signals.

Therefore, in this case, the outputs of these piezoelectric cables 55, 55... can be added,
It is possible to detect minute underwater sounds more effectively.

Furthermore, in each of the embodiments described above, the voltages generated in the outer layer and inner layer of each of the piezoelectric cables 41b to 41d, 53, and 55 are inverted as they are and added to each other. If the acceleration voltage and the acceleration voltage generated in the inner layer cannot be made equal due to design considerations, it goes without saying that a gain adjuster may be used to make them equal.

As explained above, the underwater receiver according to the present invention receives underwater sound using a piezoelectric cable in which two piezoelectric parts are arranged concentrically and a sound insulating layer is formed between them. Even when there is severe vibration noise caused by cable vibrations caused by ship motion or wind waves, it is possible to generate a voltage between these piezoelectric parts that corresponds only to the underwater sound, and to connect these piezoelectric parts in a depolarized manner. Therefore, the acceleration voltage caused by the vibration noise can be canceled and only the voltage based on underwater sound can be extracted. Therefore, minute underwater sounds can be measured with high precision even when the underwater receiver is vibrating.

[Brief explanation of drawings]

Figure 1 is a partially cutaway side view showing an example of a conventional underwater receiver, Figure 2 is a cross-sectional view of a conventional piezoelectric cable used in such an underwater receiver, and Figure 3 is a cross-sectional view of a conventional piezoelectric cable used in such an underwater receiver. A cross-sectional view of a piezoelectric cable used in an underwater receiver according to the present invention, FIG. 4 is a circuit diagram showing an example of connection between the outer layer part 11 and the inner layer part 12 of the piezoelectric cable shown in FIG. 3, and FIG. FIG. 6 is a partially cutaway side view showing a first embodiment of the underwater receiver according to the invention, FIG. 6 is a partially cutaway side view showing a second embodiment of the underwater receiver according to the invention, and FIG. FIG. 7 is a partially cutaway side view showing a third embodiment of the underwater receiver according to the invention. 10...Piezoelectric cable, 11...Outer layer part (first
piezoelectric body part), 12... Inner layer part (second piezoelectric body part), 13... Sound insulation layer, 25, 49, 57... Underwater receiver, 41b to 41d, 53, 55... Piezoelectric cable (Sensory part).

Claims (1)

[Claims] 1. An underwater receiver that converts underwater sound waves into electrical signals and extracts them using a piezoelectric cable in which the insulator portion of the coaxial cable is made of a piezoelectric material,
A first piezoelectric body part and a second piezoelectric body part are arranged concentrically, and a sound insulating layer is provided between the first piezoelectric body part and the second piezoelectric body part. An underwater receiver characterized in that underwater sound waves are converted into electrical signals and extracted by a piezoelectric cable formed by connecting a piezoelectric body part and a second piezoelectric body part in series with opposite polarities. . 2. Claim 1, wherein the piezoelectric cable comprises at least one sound-sensing section divided in the length direction, and the sound-sensing section is formed in a coil shape or a straight shape. Underwater receiver described in section.