A broadband underwater acoustic transducer array

Abstract

The present invention belongs to the technical field of ultrasonic transducers, and in particular relates to a wide-band underwater acoustic transducer array, comprising more than one transducer array, all of which have the same central frequency, each transducer array comprising a plurality of array elements of the same or different numbers, and the height difference between adjacent array elements being the same. By adjusting the height of the array elements in the transducer array, the resonant frequency of the array elements is changed, and by aliasing multiple adjacent resonant frequencies, the bandwidth of the transducer array is widened, thereby increasing the bandwidth of the array; array supports are provided between the array elements, and piezoelectric sensors are provided between the array element supports and the outer shell of the array to detect and obtain shell noise signals. The underwater acoustic transducer array of the present invention increases the receiving and transmitting bandwidths and improves detection accuracy; by detecting and generating a reverse polarity noise suppression signal, the interference of the original noise signal on the signal receiving unit is offset, thereby improving the signal-to-noise ratio, and having the advantages of high receiving sensitivity and strong transmission.

Description

Technical Field

[0001] The present invention belongs to the technical field of ultrasonic transducers, and in particular relates to a broadband underwater acoustic transducer array. Background Art

[0002] Sound waves are considered the only information carrier capable of long-distance ocean transmission. Marine research, resource development, and maritime military operations all rely on underwater acoustic technology. The development of underwater acoustic devices is closely linked to technological advancements in underwater acoustic transducers, which transmit and receive acoustic signals underwater. This advancement primarily involves the application of new materials, processes, and structural designs to improve and enhance the transducer's overall technical performance.

[0003] Based on different requirements, a certain number of underwater acoustic transducers are arranged in a specific pattern to form an array to improve the overall transmit response and receive sensitivity, thereby enhancing the signal-to-noise ratio. Since an array is composed of several transducers, parameter differences between them can degrade the overall array acoustic performance. Therefore, ensuring the consistency of the underwater acoustic transducers that comprise the array is crucial. The array design goal is to improve the overall array transmit response and receive sensitivity while maintaining a certain bandwidth to increase the transducer's transmit and receive frequency range. During propulsion, the underwater vehicle's homing head array's power unit, propeller, and other components provide vibration excitation to the hull. These vibration characteristics are related to the vehicle's speed, depth, and structure, causing noise vibrations in the hull of the underwater vehicle, which in turn interferes with the homing acoustic array. Therefore, vibration and noise reduction must be implemented during the manufacture and installation of the underwater acoustic transducer array. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and propose a broadband underwater acoustic transducer array.

[0005] To achieve the above objectives, the present invention provides a broadband underwater acoustic transducer array, comprising more than one transducer array, all of which have the same center frequency, each transducer array including a plurality of array elements of the same or different numbers, with the same height difference between adjacent array elements, and by adjusting the height of the array elements in the transducer array to change the resonant frequency of the array elements, and by aliasing multiple adjacent resonant frequencies, the frequency bandwidth of the transducer array is widened, thereby increasing the frequency bandwidth of the array;

[0006] An array bracket is provided between the array elements, and a piezoelectric sensor is provided between the array element bracket and the shell of the base array for detecting and obtaining a shell noise signal.

[0007] Preferably, the array elements in each of the transducer arrays are connected in parallel.

[0008] Preferably, the base height of each transducer array is m mm, the height difference between adjacent elements is n mm, and the height difference between adjacent elements is 0.1 mm. <n<0.5mm。

[0009] Preferably, for a certain transducer array, the frequency constant of each array element is N, and the resonant frequency of the x-th array element is N / (m+xn).

[0010] Preferably, the shell noise signal detected by the piezoelectric sensor is subjected to Fourier decomposition to obtain a noise spectrum, the noise spectrum is subjected to reverse polarity processing, and a reverse polarity noise suppression signal with equal amplitude and opposite phase is output, and the reverse polarity noise suppression signal is weighted and sent to the receiving unit of the base array to reduce the interference of the shell noise.

[0011] Preferably, while ensuring that the overall diameter of the array element remains unchanged, the diameter of the piezoelectric ceramic of the array element is increased and the thickness of the outer glue injection layer is reduced.

[0012] Preferably, the connecting wires of the matrix are nickel sheet leads, which are welded using a spot welder.

[0013] Compared with the prior art, the advantages of the present invention are:

[0014] 1. The present invention adjusts the resonant frequency of each element in the transducer array by adjusting the height of each element, so that each element produces a different resonant frequency and has a certain bandwidth impedance curve. By aliasing multiple adjacent resonant frequencies, the bandwidth of the entire transducer array is widened, thereby increasing the array's receiving and transmitting bandwidth and improving detection accuracy.

[0015] 2. The present invention uses reverse polarity common mode noise suppression technology to detect and generate reverse polarity noise suppression signals to offset the interference of the original noise signal on the signal receiving unit, thereby improving the signal-to-noise ratio;

[0016] 3. The present invention improves the consistency of transducer parameters by changing the welding method of transducer array electrodes and connecting wires;

[0017] 4. The present invention increases the diameter of the piezoelectric ceramic, thereby increasing the reaction contact area of ​​the ceramic wafer and improving the receiving sensitivity and emission intensity of the transducer array element. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 1 is a schematic top view of the transducer array arrangement of the present invention;

[0019] Figure 2 This is a schematic diagram of widening the frequency band by aliasing multiple resonant frequency points in the same array;

[0020] Figure 3 This is the schematic diagram of reverse polarity noise suppression;

[0021] Figure 4 This is a diagram of the reverse polarity noise suppression installation;

[0022] Figure 5 This is a three-dimensional schematic diagram of an array element without soldered leads;

[0023] Figure 6 It is a three-dimensional schematic diagram of the soldering lead array element;

[0024] Figure 7 It is a three-dimensional schematic diagram of an array element in which a spot welding machine is used to weld leads in the present invention. DETAILED DESCRIPTION

[0025] To solve the above problems, the technical solutions adopted include:

[0026] 1. The resonant frequency f of a transducer element in the height direction is equal to the frequency constant N of the element itself divided by the height h of the element, that is, f = N / h. Therefore, adjusting the height of the transducer element can change the resonant frequency (i.e., the resonance frequency) of the transducer element, and the transducer element trigger circuit usually operates near the resonance point. The transducer array is generally composed of 5-21 columns, each column consisting of several transducer elements. Adjusting the height of each transducer element in each column of the transducer array can change the resonant frequency of the transducer element. By aliasing multiple adjacent resonant frequencies, the bandwidth of the entire transducer array is broadened, thereby improving the array's reception and transmission bandwidth.

[0027] 2. Reverse polarity noise suppression technology. A piezoelectric sensor is installed between the array bracket and the underwater vehicle shell. The piezoelectric sensor detects the shell noise signal caused by different vibration sources, and the noise signal spectrum is obtained through Fourier decomposition. The noise signal spectrum is reversed polarity, and a reverse polarity noise suppression signal with equal amplitude and opposite phase is output. The reverse polarity noise signal is weighted and sent to the transducer array receiving unit. The addition of this reverse polarity signal offsets the original noise signal, thereby reducing the interference of the shell noise signal on the receiving unit and improving the signal-to-noise ratio of the array.

[0028] 3. The underwater vehicle array operates in a humid, salt-fog, moldy climate environment. Colloid is usually used to coat the outer surface of the transducer unit. Due to the large damping coefficient of the colloid, the vibration of the transducer ceramic piece is suppressed, which in turn leads to a significant reduction in the mechanical quality factor Qm of the transducer, resulting in a reduction in the transducer's receiving sensitivity and transmitting response. While ensuring that the overall diameter of the transducer array element remains unchanged, the diameter of the piezoelectric ceramic of the transducer unit is increased and the thickness of the outer layer of glue injection is appropriately reduced. While increasing the reaction contact area of ​​the ceramic chip and improving the receiving sensitivity and transmitting intensity of the transducer unit, the thickness of the outer layer of glue injection is reduced, the damping coefficient of the colloid is reduced, and the Qm value of the transducer is correspondingly increased, further improving the receiving sensitivity and transmitting intensity of the transducer unit.

[0029] 4. To improve the consistency of transducer unit production and manufacturing, the welding method of the electrode leads is improved to prevent the problem of uneven solder joint sizes during manual welding. Nickel strip leads are used instead, and the electric welding machine current welding method is adopted. This welding method basically has no solder joints, preventing the solder joints from changing the external shape structure of the transducer and solving the problem of parameter dispersion of the transducer caused by inconsistent solder joint sizes.

[0030] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0031] Embodiment

[0032] An embodiment of the present invention provides a broadband underwater acoustic transducer array. The transducer array is composed of more than one transducer array. Each transducer array is composed of several transducer elements. Each transducer element has its fixed resonance frequency and bandwidth. The resonance frequency is mainly related to the material of the components forming the transducer and the height of the transducer element. By adjusting the height of each transducer element in the transducer array, the resonance frequency of the transducer elements in the array is changed. By aliasing multiple adjacent resonance frequencies, the bandwidth of the entire transducer array is broadened to improve the bandwidth of the array. Figure 1 、 Figure 2 This will be described below. Figure 1 The transducer array is composed of 7 arrays. Here, the 7 arrays are only for illustration and not for limitation. Each array contains 5, 6, 7, 8, 7, 6, 5 transducer elements from top to bottom and is named array 1 to array 7 in sequence. Taking array 1 as an example for description, there are 5 transducer elements in the array. Here, the 5 elements are only for illustration and not for limitation. The basic height of each transducer element is set as m, and the height difference between adjacent two transducer elements is n (0.1 mm < n < 0.5 mm). The heights of the transducer elements from element 1 to element 5 are m + 5n, m + 4n, m + 3n, m + 2n, m + n respectively. Assuming the frequency constant of each transducer element is N, the resonance frequencies of the transducer elements from element 1 to element 5 can be obtained as N / (m + 5n), N / (m + 4n), N / (m + 3n), N / (m + 2n), N / (m + n) according to the resonance frequency calculation formula, and the resonance frequencies gradually increase. The frequency impedance characteristics of each element are as Figure 2 shown. Since the transducer elements of each array are connected in parallel, the parallel impedance curve of the transducer elements of array 1 is as Figure 2 shown. By aliasing multiple adjacent resonance frequencies, the bandwidth of the entire transducer array is broadened, improving the bandwidth of the array to achieve a higher detection bandwidth.

[0033] As Figure 3 shown is the schematic diagram of anti-polarity noise suppression. Figure 4As shown in the installation diagram, an array bracket is installed between the array elements. A piezoelectric sensor is installed between the array bracket and the outer shell to detect the noise signal transmitted from the shell to the array bracket. This noise signal is transmitted to the array transducer through the bracket, thereby generating noise interference on the transducer and the entire array. The noise signal detected by the piezoelectric sensor is subjected to Fourier decomposition to obtain a noise spectrum. This noise spectrum is then subjected to polarity reversal processing to output a reversed polarity noise suppression signal with equal amplitude and opposite phase. The reversed polarity noise signal is weighted and transmitted to the transducer array receiving unit. The addition of this reversed polarity signal offsets the original noise signal, thereby reducing the interference of the shell noise signal on the receiving unit and improving the signal-to-noise ratio of the entire array.

[0034] The high-quality, broadband underwater acoustic transducer array consists of the transducer's main piezoelectric ceramics, electrodes, leads, a radiating tip, an adjustment block, a center screw, and a compression nut. Each component is rigidly connected using epoxy resin bonding and curing.

[0035] To improve the transducer's element transmission intensity and receiving sensitivity, the diameter of the piezoelectric ceramic used in the original transducer element was increased from 16mm to 17mm, increasing the ceramic electrode's contact area and boosting both the transducer's receiving sensitivity and transmission intensity. Simultaneously, the thickness of the outer coating was reduced from 1.5mm to 1mm. This reduced the damping of the coating without compromising the installation dimensions, thereby improving the transducer's quality factor.

[0036] like Figure 5 The figure shows a three-dimensional schematic diagram of an array element without soldered leads. Figure 6 The figure shows a three-dimensional schematic diagram of the soldering lead array element. Conventional transducer electrode sheets are 0.05-0.2mm copper electrodes, which are connected by wire soldering. The size of the solder joints is uneven, which will cause differences in the overall weight and structure of the transducer array element, resulting in a certain dispersion of parameters such as the transducer resonant frequency and Qm value, increasing the difficulty of subsequent impedance matching. In this example, the original connecting wire is replaced with a nickel sheet with a thickness of 0.1-0.3mm and a width of 3mm. A spot welder is used for welding. In order to improve welding reliability, the electrode sheet in this embodiment uses a nickel sheet with a thickness of 0.1mm. Figure 7 The principle of the spot welder is to use the contact resistance caused by two contact points to weld under the thermal effect of current. The current and welding time of the spot welder are adjustable, so the weld point consistency is good. Apart from the electrode leads, no other material weight is added, and there is no impact on the electromechanical parameters of the transducer array element.

[0037] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention and are intended to be encompassed by the claims of the present invention.

Claims

1. A broadband underwater acoustic transducer array, characterized in that: The invention comprises more than one transducer array, wherein all the transducer arrays have the same center frequency, each transducer array comprises a plurality of array elements of the same or different numbers, and the height difference between adjacent array elements is the same. By adjusting the height of the array elements in the transducer array, the resonant frequency of the array elements is changed, and by aliasing multiple adjacent resonant frequencies, the bandwidth of the transducer array is widened, thereby increasing the bandwidth of the base array; An array bracket is provided between the array elements, and a piezoelectric sensor is provided between the array bracket and the shell of the array to detect and obtain the shell noise signal; Performing Fourier decomposition on the shell noise signal detected by the piezoelectric sensor to obtain a noise spectrum, performing polarity reversal processing on the noise spectrum, outputting a reverse polarity noise suppression signal with equal amplitude and opposite phase, and performing weighted processing on the reverse polarity noise suppression signal before sending it to the receiving unit of the base array to reduce interference from the shell noise; The connecting wires of the matrix are nickel sheet leads, which are welded by a spot welding machine.

2. The broadband underwater acoustic transducer array according to claim 1, characterized in that: The array elements in each of the transducer arrays are connected in parallel.

3. The broadband underwater acoustic transducer array according to claim 1, characterized in that: The base height of each transducer array is m mm, and the height difference between adjacent elements is n mm, 0.1 mm <n<0.5mm。 4. The broadband underwater acoustic transducer array according to claim 3, characterized in that: For a certain transducer array, the frequency constant of each array element is N, and the resonant frequency of the x-th array element is N / (m+xn).

5. The broadband underwater acoustic transducer array according to claim 1, characterized in that: While ensuring that the overall diameter of the array element remains unchanged, the diameter of the piezoelectric ceramic of the array element is increased and the thickness of the outer layer injection is reduced.

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