JPS59176992A - Underwater sound wave receiver - Google Patents

Abstract

PURPOSE:To attain measurement with high accuracy by arranging concentrically two piezoelectric sections and also receiving underwater echo sound by a piezoelectric cable forming a sound shield layer between the piezoelectric sections so as to extract an output voltage only based on the underwater sound. CONSTITUTION:When only the underwater sound is received by the piezoelectric cable 10, since the underwater sound is cut off by a sound shield layer 13, a sound output voltage Es from an outer layer part 11 only is generated. When the vibration such as a ship, a wave or the like is applied to the cable 10 together with the underwater sound, a voltage caused by the vibration acceleration is generated in piezoelectric rubbers 16 and 21, and the underwater sound is cut off by the sound shield layer 13. In this case, the outer layer part 11 outputs a voltage being the addition between the output voltage Es by the underwater sound and a voltage Ealpha by the vibration acceleration and an inner layer part 12 outputs an accelerating voltage -Ealpha only by the oscillation acceleration, then the same voltage Es as the case with the underwater sound only is outputted between output terminals 17 and 22.

Description

[Detailed description of the invention]

This invention uses a sound insulating material in the middle of the piezoelectric body part of the 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 polarity, so that the sound is generated on the inner layer side. By extracting the voltage difference between the output generated on the outer layer side and the output voltage generated on the outer layer side, a piezoelectric cable that can obtain only the output voltage based on underwater sound even when acceleration is applied to this piezoelectric cable was used in the wave receiving part. This relates to underwater receivers. 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 20, and piezoelectric cables 3.3 are provided inside this case 1. Each piezoelectric cable3. -3... is a device that 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 center 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.
According to the pressure fluctuations G applied to these piezoelectric cables 3, 3, a corresponding voltage 2 is generated and supplied to the preamplifier 8 in the case. The preamplifier 8 increases the output of the piezoelectric cables 3, 3, . It is supplied to a signal processing device (not shown). In this way, in the conventional underwater receiver 2, the sound waves received by the case IG are transmitted to the piezoelectric cables 3, 3...G via the insulating liquid 4, and are handled here. After converting the electrical signal, it is amplified by a preamplifier 8 and supplied to the subsequent circuit. By the way, in this underwater receiver 2, when measuring underwater sound, vibrations caused by wind waves, water currents, or the movement of the ship itself are transmitted to the receiver via the cable, and this vibration is transmitted to the receiver. are transmitted to the piezoelectric cables 3, 3..., which generate acceleration output voltages, making it difficult to accurately measure underwater sound.
It had the disadvantage of causing a G strain. In view of the above points, this invention is designed to extract only the output voltage based on underwater sound even when acceleration due to unnecessary vibrations is transmitted and applied to the underwater receiver due to wind waves, water currents, or the movement of the ship itself. It is an object of the present invention to provide an underwater wave receiver that can perform the following: In the underwater wave receiver according to the present invention, the first piezoelectric body part and the second piezoelectric body part are arranged concentrically. In addition, a sound insulating layer is provided between the first piezoelectric body part and the second piezoelectric body part, and the first piezoelectric body part and the second piezoelectric body part are connected in series with opposite polarities. This invention is characterized by converting underwater sound waves into electrical signals and extracting them using a piezoelectric cable made of a piezoelectric cable.This invention will be explained below based on an embodiment shown in the drawings.Figure 3 shows an underwater device according to the invention. FIG. 3 is a cross-sectional view showing an example of a piezoelectric cable used in a wave receiver, and FIG. This piezoelectric cable 10 has an outer layer portion arranged concentrically]
], an inner inner layer part 2, and a sound insulating layer 1 formed between these
It is composed of 3. The outer layer portion 11, inner layer portion 12, and sound insulating layer 13 will be explained below in order. First, the outer layer part 11 has a cylindrical outer conductor 14 and a concentric shape with respect to the outer conductor 14.

[The cylindrical first
The outer conductor 14 of the outer layer 11 is connected to one output terminal 17 as shown in FIG. and the first intermediate conductor 15 is an intermediate terminal]
8 is connected. Furthermore, the inner layer section 12 includes a first 2' 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]9, and a center conductor 20 disposed on the central axis of the second intermediate conductor. The center groove body 2o of this inner layer portion 12 is connected to the intermediate terminal 18, and the second intermediate conductor 19 is connected to the other intermediate terminal 18. It is connected to the output terminal 22. 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. Underwater sound received by the piezoelectric cable 1° is blocked by this sound insulating layer 13. The signal is not transmitted to the inner layer portion 12 located inside the layer 13. Next, the underwater sound detection operation of this piezoelectric cable 1° having the above configuration will be explained. First, when only underwater sound is received by the piezoelectric cable 1o, this underwater sound is cut by the sound insulating layer 13 and is not supplied to the inner layer 12 of the sound insulating layer 13. Only the section 11 generates an output voltage E3 corresponding to the sound wave, which is sent to the output terminals 17' and 2.
2 and supplied to a signal processing circuit (not shown). Next, in this state, when the piezoelectric cable 10G is subjected to vibrations caused by the motion of the ship, wind and waves, etc., the piezoelectric rubbers 16 and 2 are
1, a voltage (acceleration voltage) is generated due to vibration acceleration. Since underwater sound is cut by the sound insulating layer 13 as in the case described above, in this case, the outer layer section 11 outputs a voltage Es+Eα which is the sum of the output voltage Es due to the underwater sound and the voltage (acceleration voltage) Eα due to vibration acceleration, Inner layer section] 2 outputs an acceleration voltage -Ect due to only vibration acceleration, and as a result, a voltage obtained by adding these voltages Es+Eα and acceleration voltage -Eα from between output terminals 17' and 22, that is, the same as when only underwater sound is generated. A voltage Es is output. In this way, in this piezoelectric cable 10, the sound insulation layer 1
3 [Thus, by blocking the sound waves, a pressure difference is generated between the outer layer portion 11 and the inner layer portion 12 due to the sound waves, and this is taken out. It is possible to cancel out the acceleration voltage caused by the above and make it 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 (a cylindrical case made of fiber) is provided on the inner surface of this cylindrical case 24. These cylindrical cases 24 are provided with
One end of the outer cylindrical part 27 consisting of tension members 26 and 26 is closed with a fastening stem 30 by means of tightening bands 28, 29, and the other end is closed with a cable connection part 33 by means of tightening bands 3], , 32, which An inner cylindrical portion 35 is disposed within the closed space 34 formed by the above. The inner cylinder part 35 has a cylindrical part 7 (for example, a vinyl hose) 36 having a large number of holes penetrating the outside and the inside thereof,
Clamps 37 that close both ends of this cylindrical case 36
□ 38, the inside b of the cylindrical case 36, the short cylindrical cushion rubbers 39a to 39d arranged, the preamplifier 4° and the piezoelectric cable held by these cushion rubbers 39a to 39d, respectively]0. It is composed of each piezoelectric cable 41b to 4]d wound into a coil. The cylindrical case 36 of the cylindrical portion 35 is attached to short cylindrical cushion rubbers 42a to 42d provided so as to come into contact with the inner surface G of the outer cylindrical portion 27.
: One stopper 37 of the inner cylindrical part 35 of the box is pulled to the left (leftward in the figure) by the elastic rope 43 provided at the cable connection part 33, and the other stopper 37 is pulled to the left (to the left in the figure) Fasten the metal fitting 38 forward and attach it to the trunk 3o 44
It is pulled to the right by the bent elastic lobes 44, and tension is applied to the inner cylinder portion 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 wave receiver 25 are easily transmitted to the piezoelectric cables 41b to 4]d. When this underwater receiver 25 is suspended or towed, both underwater sound and vibrations transmitted via the cable 47 due to the motion of the ship, wind waves, etc.
Through cushion rubber 42b to 42d, cylindrical case 3
6 and cushion rubbers 39b to 39 arranged to correspond to the cushion rubbers 42b to 42d, respectively.
d't' is transmitted to each piezoelectric cable 41b to 41d via each acoustic medium of the insulating liquid OIL. As a result, the outer layer and inner layer of each of the piezoelectric cables 41b to 41d generate voltage signals corresponding to the acoustic signals and mechanical vibrations, cancel out the acceleration output voltage caused by the mechanical vibrations, and generate sound. Only the output voltage is supplied to the preamplifier 4o via each of the signal lines 45b to 45d, and the signal amplified here is supplied to a signal processing device (not shown) via the signal line 46 and cable 47 in sequence. . In this embodiment, the piezoelectric cable 41
b to 41d are arranged at predetermined intervals, and the underwater sound and vibration noise received at the external part 27 are detected by the pressure cable 41b, and these σ] pressure cables 41b to 4 are
If the phase difference of each signal output from 1d is fully detected, the direction of underwater sound can be determined from this detection result.In this case, each piezoelectric cable 41b to 41d is wound in a coil shape and By increasing the packaging density and increasing the capacitance, we aim to improve the S//IVJ (signal-to-noise) ratio σ]. Next, a second embodiment of the underwater receiver according to the present invention will be explained with reference to FIG. Since it is similar to the underwater receiver 25 shown in Figure 5, only its central part is shown, and the same parts as those shown in Figure 5G are given the same sigma. In this figure, reference numeral 50 denotes a short cylindrical porous cushion rubber (for example, sponge) 5 that is in contact with the inner surface of the outer cylindrical portion 27.
1b to 51e, the inner cylinder part 50 includes an inner cylinder case 36 having a large number of holes, and a cylindrical porous cushion provided so as to come into contact with the inner surface of the inner cylinder case 36. It is composed of rubber 52, 52, . . . and a linear piezoelectric cable 53 sandwiched between these porous cushion rubbers 52, 52, . In this way, in this underwater receiver 49, since the piezoelectric cable 53 formed in a straight line is used, cable vibrations caused by underwater sound, ship motion, wind waves, etc.
, these signals are transmitted to the piezoelectric cable 53 by the insulating liquid OIL filled in the outer cylindrical part 27, where they are converted into corresponding electrical signals and then sent to a preamplifier and a preamplifier as shown in FIG. The signal is sequentially supplied to the signal processing device via the cable. FIG. 7 is a partially cutaway side view showing a third embodiment of the underwater receiver according to the present invention. In this figure as well, parts corresponding to those in FIG. 5 are designated by the same reference numerals. In this figure, 55.55... is the inside of the outer cylinder part 27 (
These are linear piezoelectric cables arranged as shown in FIG.
The cylindrical porous cushion combs 56, 5 are in contact with each other.
6. (They are held together like this.) Like this (underwater receiver 57 &
By bundling a plurality of linearly formed piezoelectric cables 55, the vibrations of the outer cylindrical portion 27 can be absorbed by the porous insulation combs 56, 56... (which are impregnated with an insulating liquid OI).
It is possible to transmit the information through each piezoelectric cable 55° 55... through L, and to replace this with a plurality of identical electric words. Therefore, in this case [here, these piezoelectric cables 55
, 55... can be added, and it is possible to detect minute underwater sounds more effectively. Also, in each of the above-mentioned embodiments, each piezoelectric cable 41b to 41d, the voltages generated in the outer layer and inner layer of 53.55 are inverted as they are and added to each (
However, if the acceleration voltage generated in the outer layer and the acceleration voltage generated in the inner layer cannot be equal due to design reasons, it is of course possible to make them equal using a gain adjuster. . As explained above, the underwater receiver according to the present invention has two
Because the piezoelectric cable has two piezoelectric parts arranged concentrically and a sound insulating layer formed between them to receive underwater sound, there is strong vibration noise caused by cable vibration caused by the motion of the ship, wind waves, etc. In this case, it is also possible to generate a voltage between these piezoelectric parts that corresponds only to the underwater sound, and because the G is applied so that these piezoelectric parts are connected with opposite polarity, the acceleration voltage due to the vibration noise, ゛It is possible to extract only the voltage based on underwater sound by canceling out the voltage generated by the underwater sound.This allows even the underwater receiver to vibrate even when the underwater receiver is vibrating due to vibrations transmitted through the cable due to wind waves, water currents, or the movement of the ship itself. Underwater sound can be measured with high precision.

[Brief explanation of the drawing]

Figure 1 is a cutaway side view of 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. 4 is 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 the connection between the outer layer 11 and the inner N part of the piezoelectric cable shown in FIG. 3; FIG. 5 is a partially cutaway side view showing a first embodiment of an underwater receiver according to the present invention, and FIG. 6 is a partially cutaway side view showing a second embodiment of an underwater receiver according to the present invention. FIG. 7 is a partially cut side view showing a third embodiment of the underwater receiver according to the present invention. DESCRIPTION OF SYMBOLS 10... Piezoelectric cable, 1]... Outer layer part (first piezoelectric body part), 12... Inner layer part (second piezoelectric body part), 13...
...Sound insulation layer, 25,49.57...Underwater receiver, 4
1b-4] d, 53.5'5...Piezoelectric cable (acoustic sensor part). Patent Applicant Director of the Technology Research Headquarters, Defense Agency Yukie Omori Agent Patent Attorney Norimitsu Nishimura Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] ], 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, wherein the first piezoelectric material portion 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, and the first piezoelectric body part and the second piezoelectric body part are arranged concentrically. What is claimed is: 1. An underwater receiver characterized by converting underwater sound waves into electrical signals and extracting them using a piezoelectric cable formed by connecting a piezoelectric body part in series in an inverse product manner. 2. The piezoelectric cable consists of at least two or more sound-sensing parts divided in the length direction, and the sound-sensing parts are formed in a coil shape or a straight shape. Underwater receiver described in scope 1.