JP3183232B2 - Cylindrical transmitter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical transmitter suitable for use in an electroacoustic transducer that emits sound waves into water.

[0002]

2. Description of the Related Art Conventionally, this type of cylindrical transmitter emits sound waves in water using a respiratory vibration mode of a cylindrical body, and is configured as shown in FIG. 3, for example. This cylindrical transmitter will be described with reference to the same figure. In the figure, the cylindrical transmitter denoted by reference numeral 51 has an air layer A in the transmitter, and includes a piezoelectric vibrator 52 and a disk 53. And sheath 54
And an underwater cable 55.

The piezoelectric vibrator 52 is formed of a bottomless cylindrical body having electrodes 52a and 52b on its inner and outer peripheral surfaces, which are opened in both directions of the axis, and is entirely formed of a piezoelectric material such as ceramic.

Each of the disks 53 has a piezoelectric vibrator 5
The disk is composed of two disks opposed to each other with the two interposed therebetween, and is entirely formed of a rigid body such as metal. Each of the disks 53 is disposed on an opening end surface of the piezoelectric vibrator 52 so that the disk end surface closes the vibrator opening, and is incorporated in the sheath 54.

[0005] The sheath 54 is formed of a bottomed cylindrical waterproof member that covers the outer peripheral surface of the piezoelectric vibrator 52 and the outer end surface of each disk 53, and is entirely formed of a synthetic resin such as urethane. The underwater cable 55 is composed of two cables.
a, 52b.

In the thus constructed cylindrical transmitter, as shown in FIG. 4, between the underwater cable 55 and the electrodes 52a, 52b of the piezoelectric vibrator 52, the mechanical resonance frequency (fr) in the respiratory vibration mode is determined. When an electric signal of the same frequency is input, a highly efficient acoustic output is obtained by mechanical resonance of the piezoelectric vibrator 52 in the respiratory vibration mode.

The mechanical resonance frequency fr can be obtained from fr = C / 2πd (1) where C and d are the sound velocity and the average radius of the piezoelectric vibrator 52, respectively.

In order to obtain a high output sound pressure at a low frequency in such a cylindrical transmitter, the average radius d of the piezoelectric vibrator 52 is set to a sufficiently large size to reduce the mechanical resonance frequency. In addition, it is necessary to secure a large sound radiating surface. However, since there is a limit in sintering and manufacturing piezoelectric materials such as ceramics, the strip-shaped vibrator element 61 shown in FIG. As shown, a structure having a structure in which a large number are arranged in the circumferential direction is employed.

On the other hand, the outer diameter (average radius) of the piezoelectric vibrator 52
Is excessively large, the stress generated in the cylindrical transmitter 51 due to the water pressure increases when the cylindrical transmitter 51 is used at a position where the water depth is considerably deep. This stress increases in proportion to the cylinder outer diameter. When the stress is σ and the hydraulic pressure and the cylinder outer diameter are P and D, respectively, σ∝P · D.
The relationship of (2) is satisfied.

For this reason, if the generated stress is excessively large, the cylindrical transmitter 51 will be damaged. Therefore, by balancing the pressure inside and outside the cylinder and maintaining the water pressure resistant strength, the cylindrical transmitter 5 is prevented.
It is necessary to prevent the occurrence of breakage.

FIG. 7 shows an example of a cylindrical transmitter for preventing such breakage. In the figure, a cylindrical transmitter denoted by reference numeral 71 includes a piezoelectric vibrator 72, a sheath 73, and an underwater cable 74. Like the piezoelectric vibrator 52 shown in FIG. 2, the piezoelectric vibrator 72 is formed of a bottomless cylindrical body having electrodes 72a and 72b on its inner and outer peripheral surfaces, and is formed entirely of a piezoelectric material such as ceramic. Have been.

The sheath 73 is formed of a bottomless cylindrical waterproof member that opens in both axial directions and covers the entire piezoelectric vibrator 72, and is entirely formed of a synthetic resin such as urethane. The underwater cable 74 consists of two cables,
These underwater cables 74 are connected to the electrodes 72a and 72b.

[0013]

However, this type of cylindrical transmitter has a structure in which the pressure inside and outside the device is balanced by the flow of a medium into the device, that is, a structure in which the opening is opened in both axial directions. At the time of sound wave emission, the medium became respiratory vibration resistant. As a result, there has been a problem that sound waves cannot be effectively emitted and the transmission drive efficiency is reduced.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a cylindrical transmitter capable of effectively radiating sound waves and thereby reliably improving transmission driving efficiency. I do.

[0015]

According to a first aspect of the present invention, there is provided a cylindrical transmitter including a cylindrical first piezoelectric vibrator provided on an outer cylindrical sheath which opens in both directions of an axis. a first transmit element formed by burying, the tubular sheet over scan among the formation of the air layer therein by closing the two ends, opposed with a predetermined interval on the inner circumferential surface of the first piezoelectric vibrator comprising a second wave transmitting device comprising a built-in second piezoelectric vibrator cylindrical having an outer peripheral surface and a plurality of connecting sheath connecting the inner tube sheet over scan and the outer tube sheet over scan, and the The first piezoelectric vibrator and the second piezoelectric vibrator are arranged concentrically.

Therefore, the inner sheath and the outer sheath are
While flowing the medium between the first piezoelectric vibrator and
An electric signal of the same frequency is input to the second piezoelectric vibrator in the same phase.
When force is applied, each piezoelectric vibrator against the medium between the two sheaths
Are mutually canceled. In addition, multiple connection systems
The sheath connects the inner and outer sheaths.
The connection strength is increased.

[0017]

According to a second aspect of the present invention, the connection sheath is formed of a synthetic resin. Therefore, by forming the inner sheath and the outer sheath with synthetic resin, the entire sheath is integrally formed.

According to a third aspect of the present invention , a metal plate is embedded in the connection sheath with both ends of the metal plate facing the inner and outer sheaths, respectively.
Therefore, the mechanical strength of the connection sheath is increased by the metal plate.

According to a fourth aspect of the present invention, the piezoelectric vibrator comprises a plurality of vibrator elements arranged in parallel in the circumferential direction. Therefore, the piezoelectric vibrator is manufactured using a vibrator element made of a material that can be formed by sintering.

The invention according to claim 5 is configured such that the vibrator element is a strip-shaped vibrator element. Therefore, the piezoelectric vibrator is manufactured using a rectangular vibrator element made of a material that can be formed by sintering.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the drawings. FIG. 1 is a local sectional view showing a cylindrical transmitter according to the first embodiment of the present invention. In the figure, a cylindrical transmitter denoted by reference numeral 1 includes a first transmitter 2 and a second transmitter 3.

The first wave transmitting element 2 has a cylindrical waterproof structure as a whole, and has an outer sheath 4, a first piezoelectric vibrator 5, and an underwater cable 6. The outer sheath 4 is formed of a bottomless cylindrical body that opens in both axial directions, and is entirely formed of a synthetic resin such as urethane.

The first piezoelectric vibrator 5 is formed of a bottomless cylindrical body having electrodes 5a and 5b on its inner and outer peripheral surfaces, and is formed entirely of a piezoelectric material such as ceramic. The outer diameter of the first piezoelectric vibrator 5 is set to a size that can withstand an external pressure at a desired working water depth. The underwater cable 6 includes two cables, and each of the underwater cables 6 is connected to the electrodes 5a and 5b.

The second transmitting element 3 has a cylindrical waterproof structure as in the first transmitting element 2, and has an inner sheath 7, a second piezoelectric vibrator 8, an underwater cable 9 and a disk 10. ing. The inner cylindrical sheath 7 is formed of a closed-end cylindrical body having an air layer B inside by closing both ends, and is entirely formed of a synthetic resin such as urethane similarly to the outer cylindrical sheath 4. The inner sheath 7 is located at a concentric position of the outer sheath 4, and is connected to the inner peripheral surface of the outer sheath 4 by the connecting sheath 1.
1 are connected to each other.

The connection sheath 11 is composed of a large number of connection sheaths arranged in parallel at predetermined intervals in the circumferential direction at upper and lower portions of the outer sheath 4 and the inner sheath 7, and is entirely made of a synthetic resin such as urethane. . This allows
The connection strength between the outer sheath 4 and the inner sheath 7 is increased. In each of these connection sheaths 11, a metal plate 12 is provided.
Are buried with both ends of the plate facing the outer sheath 4 and the inner sheath 7, respectively. Thereby, the mechanical strength of each connection sheath 11 is increased.

The second piezoelectric vibrator 8 is formed of a bottomless cylindrical body having electrodes 8a and 8b on its inner and outer peripheral surfaces, which are open in both axial directions, and is incorporated in the inner cylindrical sheath 7. The second piezoelectric vibrator 8 is formed entirely of a piezoelectric material made of the same material as the material of the first piezoelectric vibrator 5. The outer diameter (average radius) of the second piezoelectric vibrator 8 is set to a size suitable for a desired mechanical resonance frequency.

The underwater cable 9 consists of two cables, each of which is connected to each of the electrodes 8a, 8b. The disk 10 is composed of two disks, each facing each other via the second piezoelectric vibrator 8,
The whole is formed of a rigid body such as a metal. Each of these disks 10 is disposed on the opening end surface of the second piezoelectric vibrator 8 so that the disk end surface closes the vibrator opening, and is incorporated in the inner sheath 7.

In the cylindrical type transmitter constructed as described above, in order to eliminate the radiation resistance between the two transmitting elements 2, 3 generated by the vibration of the piezoelectric vibrators 5, 8, each piezoelectric vibrator 5 The volume of each medium between the two transmitting elements 2 and 3 eliminated by the vibrations of the transmission elements 8 is made equal. This method will be described. That is, in order to equalize the volume of each medium between the two transmitting elements 2 and 3, an electric signal having the same frequency as the mechanical resonance frequency of the transmitting element 2 is applied to each of the piezoelectric vibrators 5 and 8 in the same phase. This is done by inputting independently of the items 6 and 9.

At this time, the volume V of the surrounding medium that is vibrated by each of the transmitting elements 2 and 3 is V 排除 d × α × Vin × L
.. (3). Here, d is each transmitting element 2, 3
, Α is the piezoelectric constant of the piezoelectric vibrators (piezoelectric materials) 5, 8, Vin is the input electric signal amplitude, and L is the axial length of each of the transmitting elements 2 and 3.

Now, since the materials of the piezoelectric vibrators 5 and 8 are the same in each of the transmitting elements 2 and 3, the piezoelectric constant α is the same. The axial length L is also the same. For this reason, the surrounding medium volume V which is eliminated by vibrating the respective transmitting elements 2 and 3
Is determined only by the average radius d of the transmitting elements 2 and 3 and the input electric signal amplitude Vin.

Here, the average radii of the first transmitting element 2 and the second transmitting element 3 are d10 and d11, respectively, and the electric signal amplitudes input to them are Vin10 and Vin1.
If it is set to 1, d10 × Vin10 = d11 from the equation (3).
By setting the input electric signal amplitudes Vin10 and Vin11 so as to satisfy × Vin11, the volume of the medium that the first transmitting element 2 vibrated and eliminated and the second transmitting element 3
Becomes equal to the volume of the medium removed by vibration.

Each of the wave transmitting elements 2 and 3 (piezoelectric vibrators 5 and 5)
Since 8) vibrates in the same phase, the medium density between the two transmitting elements 2 and 3 does not change.

Therefore, in the present embodiment, the medium is caused to flow between the first transmitting element 2 (the outer sheath 4) and the second transmitting element 3 (the inner sheath 7), and the first piezoelectric vibration When electric signals of the same frequency are input independently to the transducer 5 and the second piezoelectric vibrator 8 at the same phase, the radiation resistance from the piezoelectric vibrators 5 and 8 to the medium between the sheaths 4 and 7 is canceled out from each other. When the sound wave is emitted, the medium does not become a resistance of the respiratory vibration, the sound wave can be effectively emitted from the first wave transmitting element 2, and the wave transmission driving efficiency can be reliably increased.

This means that the vertical axis represents the ratio of the transmission drive efficiency of the transmitter of the present invention to the transmission drive efficiency of the conventional transmitter, and the frequency of the electric signal input to each of the piezoelectric vibrators 5 and 8 Can be understood from FIG.

In the present embodiment, a method for equalizing the volume of the medium that the first transmitting element 2 vibrates and eliminates and the volume of the medium that the second transmitting element 3 vibrates and eliminates is as follows.
A case has been described in which the adjustment is performed by adjusting the amplitude of the electric signal input to each of the piezoelectric vibrators 5 and 8. However, the present invention is not limited to this. By adjusting the axial length of each of the transmitting elements 2 and 3, Whatever you do is fine.

In this embodiment, the case where each of the piezoelectric vibrators 5 and 8 is formed as a series of cylinders has been described. However, the present invention is not limited to this. The same effect as that of the embodiment can be obtained even with a vibrator element having a shape of a circle.

In addition, the materials of the piezoelectric vibrator and the sheath according to the present invention are not limited to the above-described embodiment.

[0039]

As described above, according to the present invention, a cylindrical first piezoelectric vibrator is buried in an outer sheath, and the outer peripheral surface of the first piezoelectric vibrator is opposed to the inner peripheral surface of the first piezoelectric vibrator at a predetermined interval. A cylindrical second piezoelectric vibrator having a surface is incorporated in the inner cylinder case, and since the second piezoelectric vibrator and the first piezoelectric vibrator are positioned concentrically with each other, the inner cylindrical sheath and the outer When a medium is caused to flow between the cylindrical sheath and an electric signal of the same frequency is input to the first piezoelectric vibrator and the second piezoelectric vibrator in the same phase, the radiation resistance from the piezoelectric vibrator to the medium between both sheaths is reduced. Cancel each other out.

Therefore, the medium does not become a resistance to respiratory vibration when a sound wave is radiated as in the prior art, so that the sound wave can be effectively radiated from the first transmitting element, and the transmission drive efficiency can be reliably increased. .

Further, since the outer sheath has a structure in which the outer sheath is opened in both directions of the axis, it is possible to prevent the occurrence of stress in the transmitter during use, so that the outer diameter of the transmitter can be set to a large size. In addition, a cylindrical respiratory vibration mode can be obtained at a low mechanical resonance frequency, and it can be used even at a position where the water depth is considerably deep.

[Brief description of the drawings]

FIG. 1 is a local sectional view showing a cylindrical transmitter according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a ratio of the transmission drive efficiency of the cylindrical transmitter according to the first embodiment of the present invention to the transmission drive efficiency of the conventional cylindrical transmitter.

FIG. 3 is a local sectional view showing a conventional cylindrical transmitter (1).

FIG. 4 is a perspective view illustrating an acoustic output obtained by a conventional cylindrical transmitter.

FIG. 5 is a perspective view showing a transducer element used for a conventional cylindrical transmitter (2).

6 is a perspective view showing a conventional piezoelectric vibrator formed from the vibrator element shown in FIG.

FIG. 7 is a perspective view showing a conventional cylindrical transmitter (3).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical wave transmitter 2 First wave transmitting element 3 Second wave transmitting element 4 Outer sheath 5 First piezoelectric vibrator 5a, 5b electrode 6 Underwater cable 7 Inner sheath 8 Second piezoelectric vibrator 8a, 8b Electrode 9 Underwater cable 10 Disc 11 Connection sheath 12 Metal plate B Air layer

Claims (5)

(57) [Claims] 1. A first transmitting element in which a cylindrical first piezoelectric vibrator is embedded in an outer sheath that opens in both directions of an axis, and an air layer formed therein by closing both ends. a tubular sheet over scan, a second wave transmitting device comprising a built-in second piezoelectric vibrator cylindrical having an outer peripheral surface that face each other with a predetermined interval on the inner circumferential surface of the first piezoelectric vibrator, the inner tube and a plurality of connecting sheath connecting the sheet over scan and the outer tube sheet over scan, and feeding cylindrical, characterized in that a said second piezoelectric vibrator and the first piezoelectric vibrator concentrically Waver. 2. The cylindrical transmitter according to claim 1, wherein the connection sheath is formed of a synthetic resin. 3. The connection sheath according to claim 1, wherein a metal plate is embedded with both ends of the metal plate facing the inner sheath and the outer sheath.
Or the cylindrical transmitter according to 2. 4. The piezoelectric vibrator according to claim 1, wherein said piezoelectric vibrator comprises a plurality of vibrator elements arranged in parallel in a circumferential direction.
4. The cylindrical transmitter according to any one of the above-described items 3 to 3. 5. The cylindrical transmitter according to claim 4, wherein said vibrator element is a strip-shaped vibrator element.