JP2002044786A - Broad-band transmitter/receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain a board-band transmitter/receiver to achieve further extension of the band widths using a combined use of electric-acoustic transducer elements with a basic structure provided with a single matching layer without any need for a complexity of structure and increasing the length and size of the elements that is a multi matching layers against effects of proceeding broad- band obtained conventionally with a provision of the single layer in an elements arrangement broad-band transmitter/receiver. SOLUTION: In the element arrangement broad-band transmitter/receiver having water-proof through a process of a resin mold and the like with a plurality of arrangements of the elements added single layer matching layers 22a, 22b to a piezo-resonator 21, by using more than two kinds of combination obtained from materials having a speed anisotropy different in sound wave propagation speed depends on the direction of sound wave propagation through materials as the layers 22a, 22b, furthermore the length in the propagation direction is standardized at a length specified by special values of a matching layer in which the propagation speed is equal to the central value of faster than the central value among plural matching layers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a broadband transducer suitable for use in the ocean, such as for detecting fish schools and measuring depth in the ocean, and more particularly to a plurality of electroacoustic transducers using piezoelectric vibrators. , An element arrangement type broadband transducer.

[0002]

2. Description of the Related Art In a conventional marine transmitter / receiver, the wavelength of an underwater acoustic wave is shortened by using a higher frequency in order to improve the accuracy of acoustic measurement, or the bandwidth is increased in order to improve signal responsiveness. Techniques have been proposed. In particular, with respect to broadband technology, considerable results have been obtained by using matching layers.

In general, a matching layer used in an electroacoustic transducer of a transducer uses a piezoelectric vibrator for converting an electric signal into an acoustic signal, and an underwater ultrasonic wave transmitting / receiving apparatus, focusing on the acoustic impedance density of a matching layer material. It was selected from various materials to target the geometric mean value of the acoustic impedance density of each of the water that is the sound propagation medium in the vessel. The length dimension of the matching layer is set to の of the sound wave propagation wavelength λ in the matching layer at the operating frequency of the piezoelectric vibrator. They were mounted so that their length directions matched.

[0006] As shown in FIG. 6 (a), a single piezoelectric vibrator 1 is used for widening the band of the transducer by the matching layer.
The basic configuration is to use an electro-acoustic transducer in which one matching layer 2a is provided on the acoustic emission surface of a. Matching layer 2a is 1
If the bandwidth provided by the layers is not sufficient, FIG.
As shown in (b), by providing the second matching layer 2b or the third matching layer 2c to form a multiple matching layer, a wider band is achieved.

[0005] Even in a transducer having an array of elements as shown in FIG. 7A, it is sufficient to arrange a plurality of electroacoustic transducers each having one matching layer 2d provided on the piezoelectric vibrator 1b. If the bandwidth is not obtained, as in the case of the transducer shown in FIG. 6, a second matching layer 2e or a third matching layer 2f is provided as shown in FIG. It was common to deal with this by stratification.

[0006]

However, FIG.
In the case of a structure in which a plurality of electroacoustic transducers provided with multiple matching layers are arranged like the transducer of (b), each electroacoustic transducer is attached to one piezoelectric vibrator by a method such as bonding. Since it is formed by attaching two or more matching layers, it is necessary to prevent misalignment between the layers of the matching layer and to control the thickness of the adhesive layer. There has been such a problem that the variation in characteristics becomes remarkable with an increase in the number of adhesive layers serving as a boundary between the element and the matching layer.

Further, materials having different acoustic impedance densities are used as the second and third matching layers, and the length dimension of each matching layer in the sound wave propagation direction is determined by the sound wave propagation wavelength λ of each material. Normally, the length is increased to 1/4, and the length of the electroacoustic transducer having a configuration in which only one matching layer is provided is increased. As a result, the size of the transducer must be increased. There was another problem.

Accordingly, an object of the present invention is to provide an electro-acoustic transducer called a multi-matching layer in an element array type wide-band transmitter / receiver, in which the effect of widening the band obtained by providing a single matching layer in the prior art is obtained. Broadband transmission / reception that achieves a wider band by using a combination of electroacoustic transducers having a basic configuration with one matching layer without the need for complicated element structure and increase in length dimension. Is to provide a damper.

[0009]

According to the present invention, there is provided a wide-band transducer comprising a plurality of electroacoustic transducers each including a piezoelectric vibrator provided with a single matching layer, and an element arrangement type underwater supersonic transducer. In a sound wave transducer, two or more kinds of matching layers obtained from a material having a velocity anisotropy in which a sound wave propagation speed varies according to a direction in which a sound wave propagates in a material are used in combination as the matching layer, and the matching layer is used. This is a broadband transmitter / receiver in which the length of the sound wave propagation direction in the plurality of matching layers is unified with the length determined by the characteristic value of the matching layer in which the sound wave propagation velocity is a median value or faster than the median value.

According to the broadband transducer of the present invention, a plurality of types of matching layers having the same size and different sound wave propagation speeds in the length direction, which is the sound wave propagation direction, are provided to the piezoelectric vibrator of one specification. A plurality of electroacoustic transducers having different resonance characteristics can be obtained, and by combining them, an element array is configured to provide a wideband transmission / reception having a sensitivity characteristic obtained by combining the characteristics of the electroacoustic transducer elements having different sensitivity characteristics. Vessel.

That is, the present invention relates to an element arrangement type broadband transmission / reception in which a plurality of electroacoustic transducers each having a piezoelectric vibrator provided with a single matching layer are arrayed and made watertight by a method such as resin molding. In the wave filter, as the matching layer, a combination of two or more kinds of materials obtained from materials having velocity anisotropy having different sound propagation speeds depending on the direction of sound wave propagation in the material is used, and the length of the matching layer in the sound propagation direction is used. This is a broadband transducer that unifies the length of the matching layer with the length determined by the characteristic value of the matching layer in which the sound wave propagation velocity is a median value or faster than the median value in the plurality of matching layers.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A broadband transducer according to the present invention will be described below.

FIG. 1 is a cross-sectional view showing the arrangement of two types of electro-acoustic transducers, as viewed from the top and side, showing an element array type broadband transducer according to an embodiment of the present invention. Figure 1
(A) shows a front view of a broadband transducer, and FIG.
FIG. 1B is a cross-sectional view taken along the line AA in FIG.

In the conventional configuration, as shown in FIG. 7, when a plurality of electroacoustic transducers each having a piezoelectric vibrator provided with a single matching layer are arranged in a transducer array of element arrangement type, one type of transducer is used. Since the matching layers made of the same size from the material are applied to the respective piezoelectric vibrators by bonding or the like, the respective electroacoustic transducers have the same characteristics.

[0015] This is because, as shown in FIG. 6, the element-arranged type transducer is operated in a directivity manner with respect to the transducer having one piezoelectric vibrator to form an electroacoustic transducer. In order to avoid the occurrence of coupling vibration caused by the diameter-dimension ratio, a plurality of electroacoustic transducers having a shape in which the acoustic emission surface is subdivided,
This is because the original purpose was to replace them in an array.

That is, the transducer of the conventional configuration shown in FIG.
Electroacoustic transducer 1 having an acoustic radiation surface shape as shown in FIG.
It can be said that the transducer composed of the individual elements is reconfigured by arranging 16 subdivided electroacoustic transducers so that the shape and the outer diameter of the acoustic radiation surface are equal.

Here, since the 16 electroacoustic transducers have the same characteristics, the resonance characteristics of the transducers arranged in the element are the same as those of the single electroacoustic transducer shown in FIG. Similarly, the single resonance at the operating frequency of the piezoelectric vibrator is changed to a double resonance characteristic having two primary and secondary resonance points by providing one matching layer. Even if a plurality of are arranged, the number of resonance points does not increase further.

On the other hand, in the broadband transducer according to the present invention, by using a plurality of matching layers having the same size and different sound propagation speeds, an electroacoustic transducer having a double resonance characteristic having a shifted resonance point can be obtained. By obtaining a plurality of these and combining them, a broadband transducer having three or more resonance points is configured.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A broadband transducer according to an embodiment of the present invention will be described below.

In the broadband transducer according to the present invention, two kinds of matching layers having different characteristics are obtained from one kind of material. The material having anisotropy of the sound wave propagation velocity used as the matching layer material is the glass cloth base epoxy resin laminate 22. This material has a different acoustic wave propagation velocity in the direction along the glass cloth fiber as the base material and in the direction perpendicular to the fiber.

Conventionally, when a glass cloth base epoxy resin laminate is used as a matching layer material, either the direction along the glass cloth fibers or the direction perpendicular to the fibers is unified as the sound wave propagation direction as the matching layer. However, in the present embodiment, the first matching layer 22a whose longitudinal direction is the direction along the fiber which is the direction of sound wave propagation of the matching layer is used, and the direction orthogonal to the fiber is the sound wave of the matching layer. A second matching layer 22b having a length direction which is a propagation direction is used.

Alternatively, the first matching layer 22a,
Alternatively, instead of the second matching layer 22b, a third matching layer (not shown) using a direction oblique to the direction along the fiber as the sound wave propagation direction of the matching layer may be processed and used. It is possible.

In the glass cloth base epoxy resin laminate, as shown in FIG. 3, the sound wave propagation velocity in the X and Y directions along the glass cloth fiber is larger than the sound wave propagation velocity in the Z direction orthogonal to the glass cloth fiber. Since it shows a large value of 30% or more, two types of matching layers having the same density and different sound wave propagation velocities can be obtained. The length L of the matching layer 22a is determined by the characteristic value in the X or Y direction along the glass cloth fiber having a high sound wave propagation speed, and the matching layer 22b using the Z direction orthogonal to the glass cloth fiber as the sound wave propagation direction. Is also processed with the length dimension L.

If the matching layer 22a whose direction along the fiber is the sound wave propagation direction has a length of ４ of the sound wave propagation wavelength λa in the matching layer at the operating frequency, as in the prior art, The matching layer 22b whose direction is the sound wave propagation direction has a dimension that is substantially 30% or more longer than １ ／ of the sound wave propagation wavelength λb in the matching layer at the used frequency.

In the embodiment, the frequency is 70 kHz in the length direction.
The two types of matching layers 22 a, 2 made of a glass cloth base epoxy resin laminate 22
2b is applied by bonding to obtain electroacoustic transducers 23a and 23b having one matching layer.

As material properties of the glass cloth base epoxy resin laminate, the density ρ = 1.9 × 10 ³ (kg / cm ³ ),
Sound propagation velocity Ca = 3150 (m /
sec), sound wave propagation velocity Cb = 2 in the direction orthogonal to the fiber
340 (m / sec), the operating frequency 70
When the length of the matching layer 22a whose propagation direction is the direction along the fiber with respect to kHz is set to １ ／ of the wavelength λ, the length dimension is obtained as about L = 11.3 (mm). The length of the matching layer 22b whose direction is orthogonal to the direction of sound wave propagation is also used to form the matching layer.

FIG. 4 shows two types of matching layers 22a and 22b.
By using a thermosetting epoxy resin adhesive
FIG. 1 shows an external view of electro-acoustic transducers 23a and 23b which are formed by adhering to FIG. Both elements have the same dimensions. The graph shows the respective impedance characteristics, and the characteristics of the electroacoustic transducer 23a are the impedance frequency characteristics 24
a, The characteristics of the electroacoustic transducer 23b are as shown in the impedance frequency characteristic 24b.

Here, an electroacoustic transducer 23 to which a matching layer 22b having a direction perpendicular to the fiber as a sound wave propagation direction is bonded.
b is a matching layer 2 having a direction along the fiber as a sound wave propagation direction.
The primary resonance point shifts to a lower frequency side of about 8 kHz with respect to the electroacoustic transducer 23a to which the 2a is bonded. By combining these electroacoustic transducers 23a and 23b, a transducer having four resonance points in the resonance characteristics can be obtained.

On the other hand, in the conventional transducer configuration in which there is one kind of matching layer, there are two resonance points. In the broadband transducer according to the embodiment of the present invention, the four types of electroacoustic transducers 23a and 23b are used in each case to form a 4 × 4 array of elements, and between and around the elements. A cork 25 is adhered to perform positioning of the element and sound insulation from the surroundings. After connection with the signal cable 26, the entire body is molded with a polyurethane rubber mold 27 so as to have watertightness, and the transmission and reception of the conventional example shown in FIG. A broadband transducer having the same dimensions as the transducer was manufactured.

FIG. 1 is an explanatory diagram of a wide band transducer according to the present embodiment. The arrangement of the electroacoustic transducers 23a and 23b in this broadband transducer is arranged so that they are alternately arranged as shown in FIG. The sensitivity characteristics of the broadband transmitter / receiver thus obtained are as shown in the transmission sensitivity frequency characteristic 28 and the reception sensitivity frequency characteristic 30 in FIG. FIG. 2 shows, as a conventional example, a transmission sensitivity frequency characteristic 2 in the case where only the matching layer 22a having the direction along the fiber used in the present embodiment as the sound wave propagation direction is used in the transducer shown in FIG.
9, the reception sensitivity frequency characteristic 31 is also shown.

In contrast to the sensitivity characteristic of the transducer obtained by the conventional configuration, the broadband transducer according to the embodiment of the present invention has:
It can be seen that the bandwidth is widening. This is because the matching layer 22a
The resonance characteristic of the electro-acoustic transducer 23b provided with the matching layer 22b is shifted toward the low frequency side with respect to the resonance property of the electro-acoustic transducer 23a provided with This is because by superimposing the sensitivity characteristics with shifted bands, the band is expanded to the low frequency side, and the effect of suppressing the sensitivity change in the band is obtained.

In a conventional multiple matching layer in a transducer, multiple layers of matching layers are provided to cause multiple resonances of the piezoelectric vibrator, thereby continuously increasing the sensitivity characteristics near the resonance frequency.
In addition, the method of achieving a wide band by suppressing the sensitivity change in the band was used.However, in the wide band transducer of the present invention, a plurality of electric conversion acoustic elements are divided into several groups, and each of them is divided into several groups. By providing a shift of the resonance characteristics to the element group, it is possible to make one transducer have a plurality of resonance frequencies when the element array is formed by combining them, and the multiple matching layer is used to realize the multiple resonance of the piezoelectric vibrator. The same effect as in the case can be obtained approximately.

According to the broadband transducer of the present invention, complicated calculation for estimating the characteristics as in the case where a multiple matching layer is provided to the piezoelectric vibrator is unnecessary, and the characteristic estimation when a single matching layer is provided. Are performed a plurality of times, and the sensitivity characteristics as the transducer after the element arrangement is performed can be relatively easily estimated from the combination of these characteristics.

Further, since a plurality of matching layers can be obtained from one material, it is not necessary to investigate many matching layer materials and select and combine them.

Further, obtaining two or more types of matching layers from one material has other advantages. For example, when searching for a resin material having the same sound wave propagation speed as the matching layers 22a and 22b obtained from the glass cloth base epoxy resin laminate used in the present embodiment, a general resin material has a high sound wave propagation speed. Since the density tends to increase as the
Normally, the density of the matching layer material having a sound propagation speed equivalent to the matching layer 22a is higher than the density of the matching layer material having the sound propagation speed equivalent to the matching layer 22b.

In this case, the deviation of the resonance between the two types of electroacoustic transducers can be calculated more in comparison with the case where the density is the same.
The deviation is small. Further, from the above tendency, it is extremely difficult to find a material of different resin materials having the same density and greatly different acoustic wave propagation velocities. Therefore, the advantage of obtaining a plurality of matching layers from one material is great in terms of both characteristics and availability of matching layer materials.

In the above embodiment, a glass cloth base epoxy resin laminate is used as a matching layer, and two kinds of matching layers are obtained from a material having anisotropy of sound wave propagation velocity and used in combination to obtain the same structure. It has been shown that the effect of widening the band can be greatly obtained when only one kind of matching layer is used.
The present invention does not specify only the glass cloth-based epoxy resin laminate as the material of the matching layer, and the same effect can be obtained even if another material having a velocity anisotropy is used. However, the magnitude of the effect depends on the characteristics of the materials used, and it is not guaranteed that the same degree of effect as in the present embodiment can be obtained with a material having anisotropy.

In this embodiment, an epoxy resin laminate having a glass cloth base is used as a material having anisotropy of sound wave propagation velocity. There are epoxy resin laminates and phenolic resin laminates made of materials, and many of the resins molded with glass fiber or carbon fiber oriented in a certain direction show anisotropy of sound wave propagation velocity. Such a material can be used as a layer material.

In this embodiment, the dimension is determined such that the length of the matching layer is 1/4 of the sound wave propagation wavelength λ with respect to the sound wave propagation speed in the fiber direction of the glass cloth base epoxy resin laminate. This need not necessarily be １ ／ of the wavelength λ.

In this embodiment, the direction along the fiber of the glass cloth substrate and the direction perpendicular to the fiber are used as the sound wave propagation direction in the matching layer. If the matching layer is processed as the direction, it is possible to obtain a matching layer having a further different sound propagation speed.

[0041]

As described above, according to the present invention, the structure using the matching layer is the simplest form of a transducer in which an electroacoustic transducer having one matching layer is arranged. A simpler method of using matching layers having different characteristics and obtaining matching layers having different material characteristics from one material can provide a broadband transmitter / receiver having a wider band.

[Brief description of the drawings]

FIG. 1 is a view showing an element array type broadband transducer according to an embodiment of the present invention; FIG. 1 is a cross-sectional view showing the arrangement of two types of electroacoustic transducers as viewed from above and from a side. FIG. 1A is a front view, and FIG. 1B is a sectional view taken along the line AA in FIG.

FIG. 2 is a graph showing sensitivity characteristics of an underwater ultrasonic transducer according to the present invention and an underwater ultrasonic transducer having a conventional configuration.
FIG. 2A shows the relationship between the transmission power sensitivity and the frequency,
FIG. 2B is a diagram illustrating a relationship between received power sensitivity and frequency.

FIG. 3 is a diagram showing a relationship between a sound wave propagation direction in a glass cloth base epoxy resin laminated plate, a sound wave propagation direction of a matching layer obtained from the resin plate, and a length direction.

FIG. 4 is a diagram showing a relationship between a matching direction of two types of electroacoustic transducers and a fiber direction of a glass cloth base epoxy resin laminate. FIG. 4A is a diagram showing an electroacoustic transducer having a matching layer in which the direction along the fiber and the sound wave propagation direction are aligned,
FIG. 4B shows an electroacoustic transducer having a matching layer in which the direction along the fiber is perpendicular to the direction of sound wave propagation.
(C) is a diagram showing impedance characteristics of each electroacoustic transducer.

FIG. 5 is a cross-sectional view of a conventional transducer using an electroacoustic transducer in which one piezoelectric vibrator is provided with one matching layer, as viewed from above and from the side. FIG. 5A is a front view, and FIG.
FIG. 5B is a sectional view taken along the line BB in FIG.

FIG. 6 is a cross-sectional view of a conventional transducer using an electroacoustic transducer having a multi-matching layer by adding two matching layers as viewed from the side.

FIG. 7 is a cross-sectional view of a conventional element array type transducer in which a plurality of electroacoustic transducers each having one matching layer provided on one piezoelectric vibrator are viewed from the top and side surfaces. 7A is a front view, and FIG. 7B is a cross-sectional view taken along the line CC in FIG. 7A.

FIG. 8 is a cross-sectional view of a conventional transducer in which a plurality of electroacoustic transducers, each of which is a multi-matched layer by adding two matching layers, are arranged.

FIG. 9 is a diagram showing a conventional transducer using an electroacoustic transducer in which one piezoelectric vibrator is provided with one matching layer. FIG. 9 is a cross-sectional view as seen from the top and side surfaces of the transducer in which the acoustic radiation surface has the same shape and dimensions as those of FIG. 8. FIG. 9A is a front view, and FIG.
FIG. 9B is a sectional view taken along the line CC in FIG.

[Explanation of symbols]

 1a, 1b, 21 Piezoelectric vibrator 2a to 2f Matching layer 22 Glass cloth base epoxy resin laminate 22a, 22b Matching layer 23a, 23b Electroacoustic transducer 24a, 24b Impedance frequency characteristics 25 Cork 26 Signal cable 27 Polyurethane rubber mold 28 , 29 Transmission sensitivity frequency characteristics 30, 31 Receiving sensitivity frequency characteristics

Claims (1)

[Claims] 1. An element array type broadband transducer in which a plurality of electroacoustic transducers each having a piezoelectric vibrator provided with one matching layer are arranged and watertight by a method such as resin molding. As the matching layer, a combination of two or more types obtained from a material having a velocity anisotropy having different sound propagation speeds depending on the direction in which the sound propagates through the material, and adjusting the length of the matching layer in the sound propagation direction to a plurality of matching layers A broadband transmitter / receiver characterized in that a sound wave propagation velocity in a layer is unified with a length determined by a characteristic value of a matching layer having a median value or higher than the median value.