JP3181136B2 - Receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiver provided on an oceanographic research ship, a ship, a fishing boat, an underwater (underwater) structure or the like, and used for underwater (underwater) search or exploration by sound.

[0002]

2. Description of the Related Art As is well known, many marine research vessels and the like can perform underwater search and exploration by sound. In such a ship, as shown in FIG. 4, a receiver 2 is attached to the outer surface of the bottom of the hull 1 and the receiver 2 detects a sound wave P from the underwater target 3 to detect the position of the target 3. (Azimuth, distance) can be identified. There are two types of sound waves P: a sound wave emitted from the target itself, and a sound wave transmitted from a transmitter (not shown) attached to the hull 1 and scattered by the target 3 and returned. There is.

[0005] The receiver 2 is usually configured as shown in FIG. That is, a flexible piezoelectric member 5 formed of a piezoelectric film, a piezoelectric rubber, or the like on the outer surface of the ship bottom plate 4.
Are installed. Electrodes 6 and 7 are attached to the upper and lower surfaces of each piezoelectric body 5, respectively, and one ends of lead wires 8 and 9 are connected to the electrodes 6 and 7, respectively. The other ends of these lead wires 8 and 9 penetrate the bottom shell 4 and are connected to a signal processing device (not shown).

[0004] Each piezoelectric body 5 attached to the bottom shell 4 is
It is covered with a mold layer 10 for ensuring watertightness. As a material for forming the mold layer 10, silicon rubber or the like having a specific acoustic impedance ρC (ρ is density, C is sound velocity) is substantially equal to that of seawater is used.

When the sound wave P arrives at the surface of the piezoelectric body 5, distortion in the thickness direction occurs in the piezoelectric body 5, and an electric output is generated between the electrodes 6 and 7 by the piezoelectric effect. This electric output is guided to the signal processing device via the leads 8 and 9. The plurality of piezoelectric bodies 5 are provided in order to determine the arrival direction of the sound wave P from the phase difference of the electric output of each piezoelectric body.

[0006] However, the conventional receiver 2 configured as described above has the following problems. That is, when an engine or a propeller for propelling the hull 1 rotates, the vibration is transmitted to the bottom shell 4, and the bottom shell 4 also vibrates as shown by a broken line 11 in FIG. When the bottom shell 4 vibrates in this manner, distortion occurs in each piezoelectric body 5, and an electric output is generated between the electrodes 6 and 7. This electric output is superimposed on the electric output of the sound wave P propagating in the seawater and becomes noise. For this reason, there was a problem that the detection accuracy of the sound wave P was reduced.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a receiver capable of suppressing a decrease in detection accuracy due to the vibration of a bottom plate of a ship, that is, an attached structure.

[0008]

In order to achieve the above object, the present invention relates to a receiver for receiving sound waves by utilizing a piezoelectric effect of a piezoelectric body, wherein the receiver is used by being fixed to a structure. The wave device is characterized in that the piezoelectric body is fixed to an intermediate member having high rigidity, and the intermediate member is fixed to the structure via a vibration isolator. Preferably, the intermediate member is formed in a shape that covers the outer surface of the piezoelectric body except for the wave receiving surface.

[0009]

When vibration is excited in a structure, the vibration tends to be transmitted to the piezoelectric body. However, since the vibration isolating material and the intermediate member having high rigidity are interposed between the structure and the piezoelectric body in the above relationship, the material of the vibration isolating material and the mass of the intermediate member are related to the vibration frequency of the structure. By selecting (1) and (2), vibration transmitted to the piezoelectric body can be sufficiently reduced. Therefore,
It is possible to reduce noise caused by vibration of the structure.

If an intermediate member formed to cover the outer surface of the piezoelectric body excluding the wave receiving surface is used, the laminated structure portion composed of the piezoelectric body, the intermediate member and the vibration isolator is made of an elastic material in order to maintain watertightness. When the structure molded in is adopted, it is possible to reduce the distortion generated in the piezoelectric body due to the influence of the shear distortion that propagates in the mold layer with the vibration of the structure.

[0011]

Embodiments will be described below with reference to the drawings. FIG. 1 shows an example in which a receiver 21 according to one embodiment of the present invention is mounted on the outer surface of a bottom plate 4.

The receiver 21 is configured as follows. More specifically, a plurality of plate-like vibration isolator members 22 made of urethane or the like are fixed to the outer surface of the bottom shell 4 at equal intervals, and a rigid intermediate member made of an iron plate or the like is formed on the lower surface of these vibration isolator members 22 in the drawing. The members 23 are fixed to each other, and the piezoelectric members 24 formed of a piezoelectric film, a piezoelectric rubber, or the like are fixed to the lower surfaces of the intermediate members 23 in the drawing.

Electrodes 25 and 26 are formed on the upper and lower surfaces of each piezoelectric body 24 by vapor deposition of aluminum or silver.
Each piezoelectric body 24 is firmly fixed to the corresponding intermediate member 23 via the electrode 26. One ends of lead wires 27 and 28 are connected to the electrodes 25 and 26, respectively. The other ends of these lead wires 27 and 28 penetrate the bottom shell 4 and are connected to a signal processing device (not shown).

The laminated structure composed of the vibration isolator 22, the intermediate member 23 and the piezoelectric body 24 attached to the bottom shell 4 is covered with a mold layer 29 for ensuring watertightness. As a material for forming the mold layer 29, silicon rubber or the like having an inherent acoustic impedance ρC (ρ is a density, C is a sound velocity) substantially equal to that of seawater is used.

With such a configuration, when the sound wave P arrives at the surface of the piezoelectric body 24, a strain is generated in the piezoelectric body 24 in the thickness direction, and an electric output is generated between the electrodes 25 and 26 by the piezoelectric effect. This electric output is guided to the signal processing device via the leads 27 and 28. The signal processing device performs processing such as discrimination of the arrival direction of the sound wave P from the phase difference of the electric output of each piezoelectric body 24 and the like.

In this case, the following effects can be obtained. That is, when an engine or a propeller for propelling the hull rotates, the vibration is transmitted to the bottom shell 4, and the bottom shell 4 also vibrates as shown by a broken line 11 in FIG. When the bottom shell 4 vibrates in this manner, the vibration tends to be transmitted to each piezoelectric body 24. However, since the vibration isolating material 22 and the intermediate member 23 having high rigidity are interposed between the bottom shell 4 and each piezoelectric body 24 in the above-described relationship, the vibration isolation in relation to the vibration frequency of the bottom shell 4 is provided. By selecting the material of the member 22 and the mass of the intermediate member 23, the vibration transmitted to each piezoelectric body 24 can be sufficiently reduced. Therefore, it is possible to reduce noise caused by the vibration of the bottom shell 4.

If sufficient watertightness can be ensured without the presence of the mold layer 29, the mold layer 29 can be omitted. FIG. 2 shows an example of a receiver 21a according to another embodiment of the present invention. In this figure, FIG.
Are designated by the same reference numerals. Therefore, a detailed description of the overlapping part will be omitted.

The receiver 21a according to this embodiment differs from the receiver 21 shown in FIG. 1 in the shape of each intermediate member 23a. Each intermediate member 23a is formed in a box shape with a shallow bottom as shown in FIGS. 3 (a) and 3 (b). That is, each intermediate member 23a is formed in a shape that covers the outer surface of the piezoelectric body 24 except for the wave receiving surface. And each piezoelectric body 2
4 is fixed to the so-called bottom wall inner surface of the intermediate member 23a via the electrode 26. It is needless to say that the dimensions of each part are defined so that the electrode 25 and the electrode 26 are not short-circuited by the intermediate member 23a.

With such a configuration, it is possible to expect the same effects as in the above-described embodiment, and in particular
Since the intermediate member 23a is formed so as to cover the outer surface except for the wave receiving surface of the piezoelectric element 4, each piezoelectric element 2a is affected by the shear strain Vs propagating in the mold layer 29 due to the vibration of the bottom shell 4.
4 can be reduced, and the detection accuracy of the sound wave P can be further improved.

[0020]

As described above, according to the present invention, the transmission of the vibration excited by the structure to the piezoelectric body can be suppressed, and as a result, the detection accuracy of the sound wave can be improved.

[Brief description of the drawings]

FIG. 1 is a local sectional view showing an example in which a receiver according to one embodiment of the present invention is mounted on a bottom plate of a ship.

FIG. 2 is a local sectional view showing an example in which a wave receiver according to another embodiment of the present invention is mounted on a bottom shell.

FIG. 3 (a) is a perspective view showing an intermediate member incorporated in the receiver, and FIG. 3 (b) is a view taken along line AA in FIG. 3 (a) and viewed in the direction of the arrow.

FIG. 4 is a schematic view of an example in which a wave receiver is mounted on the outer surface of a ship bottom.

FIG. 5 is a sectional view for explaining the structure of a conventional receiver.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Hull 4 ... Bottom outer plate 21, 21a ... Receiver 22 ... Vibration-proof material 23, 23a ... Intermediate member 24 ... Piezoelectric body 25, 26 ... Electrode 27, 28 ... Lead wire 29 ... Mold layer

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tatsuo Suetsugu 1-1, Akunouracho, Nagasaki City, Nagasaki Prefecture Mitsubishi Heavy Industries, Ltd. Nagasaki Shipyard (72) Inventor Yuichi Kanda 5-717-1 Fukahoricho, Nagasaki City, Nagasaki Prefecture (56) References: Shokai 63-183572 (JP, U) Shokai 63-144798 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04R 17/00 330 H04R 1/44 330

Claims (3)

(57) [Claims] 1. A receiver for detecting a sound wave by utilizing a piezoelectric effect of a piezoelectric body, wherein the piezoelectric body is fixed to an intermediate member having high rigidity. A receiver, wherein the intermediate member is fixed to the structure via a vibration isolator. 2. The receiver according to claim 1, wherein the intermediate member is formed in a shape that covers an outer surface portion of the piezoelectric body except for a receiving surface. 3. An elastic material is provided for sealingly laminating a laminated structure portion comprising the piezoelectric body, the intermediate member and the vibration damping material.
Wave receiver as claimed in claim 1 or 2, characterized in that is.