JP2008268046A - Ultrasonic detector and sonar device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an economical ultrasonic detector capable of simplifying its structure and reducing its size and weight by simplifying an exciting signal circuit and reducing the number of connection cables to enhance its general-purpose property. <P>SOLUTION: This ultrasonic detector is constituted by arranging M partial arrays composed by arranging N ultrasonic transducers S1, S2, ..., SN linearly on its extension line repeatedly, using the transducer array composed of (N×M) ultrasonic transducers on the whole as a wave transmitter and receiver, and providing the exciting signal circuit 24 for supplying exciting signals having each deviated phase into the wave transmitter and receiver together to ensure required sound pressure of the wave to be transmitted into the direction of ultrasonic beam. The exciting signal circuit 24 outputs the same number of exciting signals as the number, N, of the transducers in one partial array and supplies the same exciting signals into the transducers arranged at the positions having the same order (order positions) in each partial array to reduce required number of exciting signals to N kinds. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to an ultrasonic detector and a sonar device, and more particularly to an ultrasonic detector and a sonar device using a linear transducer array as a transducer.
It is.

A moving body that travels on the surface of the water or underwater needs to always search for underwater obstacles that exist in the direction of travel with the intention of avoiding collisions. Detection device) is equipped.
In this case, in the case of a ship (moving body) that travels on the surface of the water, it is necessary to always search forward and downward of the bow in order to search for obstacles such as reefs. In such a case, the transducer of the sonar device is usually equipped with a method in which the transducer is tilted from the horizontal direction toward the search direction, or in a transducer including a large number of transducer elements such as a transducer array, Each input signal (excitation signal) is controlled to be delayed or phase-shifted, and the directivity (beam) is tilted, so that the transducer is physically installed horizontally. However, a method of tilting equivalently is employed (see, for example, Patent Document 1).

  If the transmitter / receiver of the ultrasonic detection device is tilted and installed in the search direction, the smooth fluid structure of the moving body is likely to be damaged. Therefore, there is an inconvenience that it becomes a great obstacle to the movement of the moving body, and in reality, there are few examples in which the transmitter / receiver is tilted and installed in a state of protruding in the search direction.

On the other hand, a transducer including a large number of transducer elements such as a transducer array can be installed almost horizontally on the bottom of the ship, and has the advantage that problems caused by disturbing the fluid structure as described above hardly occur. Yes, it is more frequently used than before.
JP-A-9-292458

  However, an excitation signal circuit for performing delay or phase control for each transducer element in order to tilt the beam, and for feeding a signal from the excitation signal circuit in the hull to each transducer element mounted on the bottom of the ship A large number of wirings (cables) are required, which complicates the cable connection and restricts space. Especially, a large number of wirings are required to individually drive a transducer array composed of a large number of transducers. In addition, there has always been the inconvenience of requiring a lot of labor for the wiring work. For this reason, there existed a problem that it was difficult to adapt to the installation to moving bodies, such as a small ship with space restrictions, for example.

(Object of invention)
In view of the disadvantages of the above-described conventional example, the present invention makes it possible to simplify the excitation signal circuit, reduce the number of connection cables, etc., simplify the apparatus, reduce the cost, and reduce the size and weight of the apparatus. It is an object of the present invention to provide a detection device and a sonar device.

  In order to achieve the above object, in the ultrasonic detection apparatus according to the present invention, a partial array in which N ultrasonic transducers are linearly arranged to form one group is repeatedly arranged on the extension line, and M groups are arranged as a whole. A transducer array composed of M ultrasonic transducers is used as a transducer, and an excitation signal circuit for sequentially supplying excitation signals whose phases are sequentially shifted to each ultrasonic transducer of the partial array is provided. The signal circuit outputs the excitation signal of a type equal to the number N of transducers in each partial array, and the transducers having the same order (arrangement position) in each of the M partial arrays have the same phase. The above-described excitation signal is supplied (claim 1).

  Therefore, according to this, the number of necessary excitation signals can be reduced to 1 / M while maintaining the directivity that is the same as the conventional excitation method, using the same transducer array as the conventional one. The configuration of the excitation signal circuit can be reduced in size and simplified, and the overall apparatus can be simplified and economically, and further, the entire apparatus can be reduced in size and weight.

The excitation signal circuit described above includes the same number of phase shifters for controlling the phase or delay of the excitation signal as the number of transducers N of the one partial array, corresponding to each transducer of the partial array individually. (Claim 2).
As a result, the excitation signal circuit can reduce the number of phase shifters to 1 / M compared with the conventional example having the same number of vibrators, and the entire apparatus can be effectively reduced in size and weight. Is done.

Furthermore, in the above-described ultrasonic detection apparatus, the phase shifter provided in the excitation signal circuit simultaneously outputs N types of excitation signals whose phases are sequentially shifted by 2π / N [radians], and the corresponding parts It supplies to each vibrator | oscillator of an array simultaneously (Claim 3).
Thereby, since the phase of the excitation signal applied to each transducer of the partial array is linearly shifted, a beam having directivity in a specific direction can be formed as the partial array. In the partial array, the number of vibrators is reduced and the aperture diameter is also reduced. However, since the frequency of the excitation signal can be set high, as a result, it can be used in a short wavelength region, so that it has a comprehensive orientation. It is also possible to configure so that the sex pattern does not change.

  Further, in the above-described ultrasonic detection apparatus, the transducers in the same order (arrangement position) in the M partial arrays are connected in parallel by a common wiring, and are connected in parallel. A configuration may be adopted in which each of the common wirings of the N vibrators and the excitation signal circuit are connected by N cables.

  In this way, the number of connecting wires (cables) from the excitation signal circuit to the transducer array can be reduced to N (1 / M of the conventional), and the excitation signal circuit and vibration can be reduced. The effect is great when the distance of the child array is long, and as a result, it has a great effect together with the excitation signal circuit for simplification, space saving, size reduction, weight saving, and economy of the entire apparatus.

Further, in the above-described ultrasonic detection device, the signal generator pre-installed in the excitation signal circuit is a variable frequency signal generator, and the frequency of the excitation signal applied to the transducer is variably set. The direction of the output beam of the transducer may be variably controlled (Claim 5).
In this way, the direction (angle) of the beam can be changed simply by changing the frequency of the excitation signal. The lower the frequency (the longer the wavelength), the closer the beam is to the upward horizontal direction (linear direction of the transducer array).

In addition, the above-described ultrasonic detection device is mounted on the hull for underwater detection, and the transducer array is disposed substantially horizontally at the bottom of the hull and along the keel line of the hull. Thus, the beam direction may be set and controlled so as to detect an underwater object located in the front lower direction (claim 6).
In this way, it is possible to exert an effect for searching forward and downward without greatly affecting the mobility and fluid structure of the ship, and the structure is reduced in size and weight. A sonar device (underwater exploration device) that can be mounted on ships can be provided.

  Since the present invention is configured and functions as described above, according to this, the required excitation signal is reduced, and accordingly, the excitation signal circuit can be greatly reduced in size, and the excitation signal circuit and the transducer array are electrically connected. Since the number of cables to be connected can be reduced, the device can be simplified and economical, and the device scale can be reduced in size and weight. A detection device and a sonar device can be provided.

First, the entire content of the ultrasonic detection apparatus according to the embodiment of the present invention will be described, and then the specific content will be described.
FIG. 1 is an explanatory diagram of a state in which the ultrasonic detection apparatus according to the present embodiment is mounted on a moving body such as a ship. This device is equipped with a transmitter / receiver 20 that generates and processes electrical transmission signals and received signals mounted on a moving body, and has a function of mutual conversion between electro-mechanical signals mounted at a place in contact with water outside the moving body. The transmitter / receiver 10 is configured to include a connecting wire (connecting wire) 30 that connects the two.

  The transmission function of the present ultrasonic detection apparatus is such that an oscillation signal from a signal generation circuit (not shown) provided in advance in the transmission / reception unit 20 is converted into an excitation signal having a different phase by an excitation signal circuit (not shown). Power is supplied to the transducer 10 via the wiring (connection wire) 30. In the transducer 10, the excitation signal, which is an electrical signal, is converted into mechanical vibration and propagated into the water as ultrasonic vibration. Here, the transducer 10 is composed of a transducer array in which a large number of ultrasonic transducers are linearly arranged, and by controlling the phase (or delay) of each excitation signal applied to each transducer, Directivity for emitting strong ultrasonic waves in a specific direction can be provided. FIG. 1 shows a state in which an ultrasonic beam having directivity is radiated at an angle θ from the vertical direction below the moving body that is the monitoring direction.

  In the ultrasonic detection apparatus, both the transmission and reception functions are realized by switching the transmission period and the reception period at short time intervals. In the transmission period, a strong ultrasonic wave is radiated into the water by the excitation signal, and when the transmission ultrasonic wave is reflected from the target object and returns to the transducer 10, the reception period is switched, and the excitation signal is cut off. The transducer constituting the transducer 10 converts the vibration of the reflected ultrasonic waves into an electrical signal and supplies it to a reception / signal processing circuit (not shown) provided in the transmission / reception unit 20. Since the characteristics of the transmitter / receiver 10 such as directivity as a transmitter / receiver are directly applied to the characteristics of the receiver / receiver, the transmission function will be mainly described below.

Next, a specific configuration of the ultrasonic detection apparatus according to the embodiment will be described with reference to FIG.
The transducer 10 has a partial array 10 ₁ , 10 ₂ ,... Formed by linearly arranging N ultrasonic transducers S 1, S 2,. As a whole, it is configured as a transducer array including (N · M) ultrasonic transducers S1, S2,. Further, an excitation signal circuit 24 and a signal generator 22 for supplying excitation signals with shifted phases are provided to the transducer 10, that is, the transducer array.

Here, the excitation signal circuit 24, the first portion array ₁₀ 1, 10 _2, N numbers of ultrasonic transducers S1, ...... or 10 _M is provided, S2, ......, at the same frequency SN N phase shifters are provided for applying excitation signals having different phases.
Thereby, the number of excitation signals equal to the number N of vibrators included in each of the partial arrays 10 ₁ , 10 ₂ ,..., 10 _M is output, and the parts in the same order (order position) in each partial array. The same excitation signal is supplied to each transducer of the array. That is, each partial array ₁₀ 1, ₁₀ 2, the first of each transducer S1 of ...... 10 _M, the same excitation signal from the phase shifter 26-1 of the excitation signal circuit 24 is supplied, each subarray 10 The excitation signals from the phase shifter 26-2 are supplied to the second transducers S2, ₁ , 10 ₂ ,..., 10 _M , and each nth transducer Sn.
In the configuration, the same excitation signal is supplied from the phase shifter 26-n of the excitation signal circuit 24.

Next, the operation and characteristics of the transducer array having such a configuration will be described.
3, each partial array _{10 1, 10 2, ......,} 10 M of the vibrator S1, S2, ......, SN
It is a figure for demonstrating the conditions for the ultrasonic wave radiated | emitted from to form a strong ultrasonic beam in the fixed direction (theta).
In order to form an ultrasonic beam, the wavefront of the ultrasonic wave radiated from each partial array 10 ₁ , 10 ₂ ,..., 10 _M is, for example, as indicated by line segment H ₁ -H ₂ in the figure. It is necessary to have it. For this purpose, for example, when attention is paid to the vibrator S1 of partial array 10 ₂ adjacent to the partial array 10 ₁ vibrator S1, are excited by the same excitation signal, the phase must be offset by 2 [pi (360) . In general, the distance d between the ultrasonic wave fronts of the two transducers corresponding to each of these adjacent partial arrays must be equal to the wavelength λ of the ultrasonic waves. To express this relationship in a formula, the radiation direction of the ultrasound beam theta, partial array 10 _1, 10 _2, ..., as each sequence length D of 10 _M, the following relationship from the official trigonometric function is established.

(Equation 1)
λ = d = D sin θ
Further, in order to form a beam vibrator S2, S3 of the partial array 10 _1, ..., ultrasonic wave radiated from the SN also, for example, it must be aligned in line _H 1 -H ₂ in Fig. Therefore, the phases of the excitation signals of these vibrators need to be shifted by 2π / N. That is, the N phase shifters 26-1, 26-2,..., 26-N provided in the excitation signal circuit 24 supply excitation signals whose phases are sequentially shifted in increments of 2π / N [radians] to the vibrator. It is configured to do.

Further, if the frequency F and the sound velocity in water are c, it is also expressed as “(c / F) = Dsin θ”, and therefore the sound velocity c, excitation frequency F, and array length D of the partial array are determined. The direction θ of the radiation beam is determined as follows:
(Equation 2)
θ = sin ⁻¹ (c / (F · D))
From the above equation (2), the direction θ of the directional beam is an environmental water in which the acoustic velocity c in the water and the arrangement length D of the partial array are constant. It can be seen that it can be changed by.

Next, the directivity of the radiation pattern by a partial array having a small number of transducers as in this embodiment will be described. In general, the directivity sharpness of the radiation pattern of the transducer array (half-value angle when the beam sound pressure is half of the peak sound pressure) is the ratio (λ / L) is known to be proportional.
Therefore, in order to direct the beam in the θ direction in the same way as before for the entire (N · M) transducer array (aperture diameter L = M · D), all the transducers have the necessary phase shift. In the case of feeding a signal having the directivity, the directivity is proportional to λ ₁ / (M · D).

On the other hand, in the partial array according to the present embodiment, the so-called opening diameter is the arrangement length D of the partial array, and the directivity is proportional to λ ₂ / D. Compared to the directivity λ ₁ / (M · D) of the conventional transducer array, if the excitation frequency is the same, the wavelength is also the same (λ ₁ = λ ₂ ), and the width of the directional beam is certainly M Will spread twice. However, the wavelength lambda ₂ in this portion arrays are dsin, whereas, the wavelength lambda ₁ is the (M · D) sinθ, the wavelength lambda ₂ is in the first M frequency compared to lambda _1. That is, since λ ₂ = λ ₁ / M, the directivity sharpness of the radiation pattern is hardly changed after all. However, the frequency is to be operated by M times.

  Thus, in the partial array employed in this embodiment, the number of vibrators is reduced and the so-called opening diameter is also reduced, so that the directivity seems to deteriorate, but the overall scale is actually 1 / M. Accordingly, by shortening the ultrasonic wavelength, that is, by increasing the excitation frequency by a factor of M, the overall directivity pattern can be operated with almost no change.

As shown in FIG. 4, portion array _{10 1,} 10 2, ..., the order within 10 _M (ordinal position) the parts the same array _{10 1,} 10 2, ..., each vibrator 10 _M S1, S2,..., SN are set as a set of vibrators by electrically connecting the excitation lead wires or excitation terminals to each other, and a set of these N vibrator groups and an excitation signal circuit. It is good also as a structure which connects the phase shifter 26 with which 24 is equipped with N connection electric wires. In the example of FIG. 4, the case where N = 4 is displayed.
That is, in the above-described ultrasonic detection apparatus, the transducers in the same order (arrangement position) in the M partial arrays are connected in parallel by a common wiring, and are connected in parallel. The common wirings for the N vibrators and the excitation signal circuit are connected to each other by N cables.
Here, in FIG. 4, it is indicated by a single line, but in reality, it is often configured by a pair of lines through which a reciprocating current flows in consideration of noise countermeasures.

With this configuration, the number of connection wires (cables) 30 from the excitation signal circuit 24 to the transducer array 10 can be reduced to N (1 / M of the conventional), and the excitation signal circuit The effect is particularly great when the distance between the vibrator 24 and the transducer array 10 is long, and it exhibits a great effect together with the simplification of the excitation signal circuit for simplification and space saving of the entire apparatus, reduction in size and weight, and economy.
As described above, in the present embodiment, the same number of transducer arrays as in the past are used, while maintaining the same directivity as in the past, and at the same time, the number of excitation signals necessary for the configuration is M minutes. The number of phase shifters 26 included in the excitation signal circuit 24 can be reduced to 1 / M, and the excitation signal circuit 24 can be simplified and downsized. .

  Furthermore, as described above, the number of connection wirings (wire cables) 30 from the excitation signal circuit 24 to the transducer array 10 can be reduced to N (1/1 of the conventional M) by the configuration shown in FIG. This makes it possible to simplify the economy of the entire ultrasonic detection apparatus, as well as to reduce the size and weight, as well as the effect of simplifying the excitation signal circuit described above.

Next, Example 1 will be described with reference to FIGS.
5 and 6, as disclosed in FIG. 1 described above, the ultrasonic detector is mounted on the hull, and the transmitter / receiver mounted on the bottom is used, and the forward and downward direction is about 45. It is used as a sonar device for monitoring the degree.

Specifically, as shown in FIG. 5, the transducer 10 is composed of a plurality of partial arrays 10 ₁ , 10 ₂ ,..., And each partial array 10 ₁ , 10 ₂ ,. It consists of vibrators S1, S2, S3 and S4. Each of the partial arrays 10 ₁ , 10 ₂ ,..., 10 _M includes the respective phase shifters 26-1, 26-2, 26-3 provided in the excitation signal circuit 24. , 26-4, the four types of excitation signals having different phases are sequentially corresponding to the excitation signals and are individually excited at the same time.

  At this time, the phase of each excitation signal is shifted by 2π / 4 = π / 2 = 90 °. For example, a signal with a phase delay of 0 ° is given to the transducer S1, and a signal with a phase delay of 270 ° is given to the transducer S2. A signal with a phase delay of 180 ° is applied to the vibrator S3, and a signal with a phase delay of 90 ° is applied to the vibrator S4. The signal generator 22 is composed of a variable frequency oscillator and oscillates at a frequency designated between the lowest frequency F1 and the highest frequency F2.

Meanwhile, the search direction theta, the use frequency F, each partial array ₁₀ 1, ₁₀ 2, when the sequence length of the ...... 10 _M is D, the beam direction theta of the ultrasonic, each portion arrays each partial array 10 ₁ , 10 ₂ ,..., 10 _M wavefront spacing “d = Dsin θ” is one wavelength of sound wave in water as described above “λ = (c / F) (where c is the speed of sound in water)” Need to be configured to be

Thus, the search direction theta, the sequence length of the transducer elements of the transducer if Kimare using frequency F is set to "D = (c / F) / sinθ ", each portion array _{10 1, 10 2, ...... 10} M of By supplying to each transducer S1, S2, S3, S4 a signal having a frequency of F and having the above-described four different phases, a transmission beam can be generated in the requested search direction θ. .

FIG. 5 shows a state in which the directivity of the ultrasonic beam changes when the frequency used is two. That is, the use frequency F1, F2, and the respective wavelengths of the time .lambda.1, and .lambda.2, 4 single vibrator S1, S2, S3, S4 each partial array ₁₀ 1 consisting of, ₁₀ 2, sequence length of the ...... 10 _M Is a direction θ ₁ satisfying sin θ ₁ = λ1 / D, and a beam direction at a use frequency F2 is a direction θ satisfying sin θ ₂ = λ ₂ / D. _The transmitted beam is directed to ₂ .

  FIG. 6 shows the calculation result of the radiation beam pattern of the transducer 10 according to the present embodiment. When the number N of the vibrators in the partial array is 4, and the vibrators are arranged at intervals of a half wavelength (λmin / 2) of the wavelength λmin at the highest frequency used (here, 200 [kHz]), that is, This is a calculation example of the directivity pattern when D = 2λmin. FIG. 6A shows a radiation pattern at a frequency of 120 [kHz] as an example. It can be seen that there is a peak of the main beam (main lobe) in the vicinity of 56 degrees with respect to the vertical direction, and there are many other side lobes.

  FIG. 6B shows an example of calculation of four directivity patterns when the frequency is changed from the lowest frequency F1 = 110 [kHz] to the frequency F2 = 140 [kHz] in increments of 10 [kHz] under the same conditions as described above. It is. As the frequency decreases, the beam radiation direction θ increases and faces upward in the figure, but the beam width increases and the directivity sharpness decreases. On the contrary, when the frequency is increased, the beam radiation direction θ is decreased and turned downward in the figure, and the beam width is narrow and the directivity is sharp.

  As described above, in the above-described embodiment, by reducing the number of necessary excitation signals to 1 / M, the number of phase shifters provided in the excitation signal circuit is also reduced to 1 / M. The signal circuit 24 can be simplified and downsized. Furthermore, it is possible to reduce the number of connection cables from the excitation signal circuit to the transducer array to N (1 / M of the conventional one), both of which make the device simpler and more economical, and the device scale. This makes it possible to reduce the size and weight.

In addition, the above-described ultrasonic detection device is mounted on the hull for underwater detection, and the transducer array is disposed substantially horizontally at the bottom of the hull and along the keel line of the hull. Accordingly, the beam direction may be set and controlled as a sonar device capable of detecting an underwater object located in the front lower direction.
In this way, it is possible to exert an effect in searching for obstacles forward and downward without greatly affecting the mobility and fluid structure of the ship, and as described in the above-described embodiments and examples, it is small and lightweight. Therefore, it is possible to obtain a sonar device (underwater exploration device) that can be mounted on a small vessel with a large space constraint.

  The ultrasonic detector can be mounted on a small ship or the like, and the practical area can be expanded. In addition, as described above, the direction of the transmitted beam can be controlled by changing the frequency of the transmission signal, which is effective in improving convenience.

It is explanatory drawing which shows the case where the ship is equipped with the ultrasonic detection apparatus which concerns on one Embodiment of this invention. It is a figure which shows the connection of the transducer and excitation circuit of the ultrasonic detector which concerns on this embodiment. It is explanatory drawing which shows the conditions of ultrasonic beam formation in this ultrasonic detector. It is a block block diagram which shows the connection structure of the transducer and excitation signal circuit which concern on this ultrasonic detector. 1 is a block diagram illustrating a configuration of an ultrasonic detection apparatus according to a first embodiment. FIG. 6 is a radiation beam pattern diagram (A diagram) in the transducer array according to Example 1, and a radiation beam pattern diagram (B diagram) when the frequency is changed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Transceiver, transducer array 10 ₁ , 10 ₂ ,..., 10 _M partial array 20 Transceiver 22 Signal generator 24 Excitation signal circuit 26 Phase shifter 30 Connecting wire (cable)
D Partial array length d Wavefront spacing between partial arrays F, F1, F2 Signal frequencies S1, S2, ..., SN Ultrasonic transducer (vibrator)
θ, θ1, θ2 Ultrasonic beam direction angle with respect to perpendicular λ, λ1, λ2 Wavelength of ultrasonic wave in water

Claims (6)

A partial array in which N ultrasonic transducers are linearly arranged to form one group is repeatedly arranged on the extension line of M groups, and a transducer array consisting of N · M ultrasonic transducers as a whole is transmitted and received. age,
An excitation signal circuit for sequentially supplying excitation signals whose phases are sequentially shifted to each ultrasonic transducer of the partial array is provided,
This excitation signal circuit outputs the type of excitation signal equal to the number N of transducers in each partial array, and the transducers arranged in the same order in the M partial arrays An ultrasonic detection apparatus characterized in that the excitation signals having the same phase are supplied.   The excitation signal circuit includes the same number of phase shifters for controlling the phase or delay of the excitation signal as the number N of transducers in the partial array, corresponding to each transducer in the partial array. The ultrasonic detection device according to claim 1. In the ultrasonic detection apparatus according to claim 1 or 2,
The phase shifter provided in the excitation signal circuit outputs N types of excitation signals whose phases are sequentially shifted by 2π / N [radians] at the same time, and supplies them simultaneously to the corresponding transducers in the partial array. Ultrasonic detector characterized by. In the ultrasonic detection device according to any one of claims 1 to 3,
The transducers in the same order in the M partial arrays are connected in parallel by a common wiring, respectively.
An ultrasonic detector characterized in that a set of N transducers connected in parallel and the excitation signal circuit are connected by N cables. In the ultrasonic detection device according to any one of claims 1 to 4,
The signal generator pre-installed in the excitation signal circuit is a variable frequency signal generator, and the direction of the output beam of the transducer is changed by variably setting the frequency of the excitation signal applied to the transducer. An ultrasonic detector characterized in that it is configured to be variably controlled.   The ultrasonic detection device according to claim 5 is mounted on a hull for underwater detection, and the transducer array is disposed substantially horizontally at the bottom of the hull and along the keel line of the hull. A sonar device characterized in that the beam direction is set and controlled so as to detect an underwater object located in the lower front.

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