High-performance broadband intermediate-frequency transducer driven by hybrid excitation source and preparation method thereof

Abstract

The invention belongs to the technical field of transducers, and discloses a high-performance broadband intermediate frequency transducer driven by a hybrid excitation source and a preparation method thereof.The transducer comprises a PMN-PT relaxor ferroelectric single crystal unit, a first support and a second support, and the first support and the second support are installed at the two ends of the PMN-PT relaxor ferroelectric single crystal unit; the end, away from the PMN-PT relaxation ferroelectric single crystal unit, of the first support is provided with a front radiation head. The end, away from the PMN-PT relaxation ferroelectric single crystal unit, of the second support is sequentially provided with a middle mass block, first piezoelectric ceramic, second piezoelectric ceramic, a tail mass block and a connecting piece. The connecting piece penetrates through inner holes of the tail mass block, the second piezoelectric ceramic, the first piezoelectric ceramic and the middle mass block to be fixedly connected with the front radiation head, two different piezoelectric materials are used for converting electric signals into sound signals in different vibration modes, the broadband performance is improved, meanwhile, the size is greatly reduced, the working stability is improved, and the service life is prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of transducers, and relates to a high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source and a preparation method thereof. Background Art

[0002] As the core component of a sonar system, the broadband performance and miniaturized design of an underwater acoustic transducer are key requirements for applications in limited spaces such as underwater unmanned vehicles, bionic robots, and portable sonar devices. Due to the physical propagation advantages of medium and low-frequency sound waves in water, such as long propagation distance, strong anti-interference ability, and high penetrability, medium and low-frequency transducers have become the focus of research. Modern sonar systems require multi-functional integration, such as simultaneous detection, communication, and navigation, which requires the transducer to operate at different frequencies, posing a broadband performance requirement for the transducer. Therefore, a miniaturized broadband medium and low-frequency transducer is needed to provide key technical support for long-distance detection, covert deployment, and operation in complex environments of underwater unmanned platforms.

[0003] However, in the field of existing transducers, miniaturization, broadband, and medium and low frequencies have always been mutually contradictory and cannot be achieved simultaneously. Due to the inherent contradiction between physical laws and material properties, the resonant frequency is inversely proportional to the characteristic size of the transducer. Traditional medium and low-frequency PZT piezoelectric ceramic transducers are huge in volume and difficult to be applied to small-space scenarios. The main existing methods for expanding the bandwidth of transducers adopt multi-modal coupling, that is, multi-excitation structures, matching layer / backing technologies, etc. The multi-excitation structure excites double resonant peaks through the size difference between the front and rear piezoelectric stacks, but it is necessary to meet a large size ratio between the front and rear piezoelectric stacks, resulting in difficulty in reducing the characteristic size of the transducer; the superposition of the same material has limited improvement in bandwidth, making there a theoretical bottleneck in size reduction. The matching layer / backing technology expands the bandwidth by means of acoustic impedance matching, still does not avoid the increase in characteristic size, and is prone to aging and failure, and is gradually being phased out.

[0004] In addition, sonar systems also need to improve the sonar detection range, resolution, and anti-interference ability, which pose higher requirements for the transmit voltage response of the transducer. Limited by the piezoelectric performance of piezoelectric materials, the maximum transmit voltage response of traditional PZT-4 piezoelectric ceramic transducers is only 130 - 140 dB, which is difficult to meet the ever-changing application requirements.

[0005] The replacement of piezoelectric functional materials provides a technical solution for the effective combination of miniaturization, broadband, and medium and low frequencies, and at the same time improves the transmit performance of the transducer. The PMN-PT relaxor ferroelectric single crystal has excellent performance, and the piezoelectric strain constant can reach more than 2800, which is 6 - 8 times that of the commonly used PZT-4 piezoelectric ceramic, and the electromechanical coupling coefficient > 0.9, which is easy to achieve impedance matching; has a small constant electric field and Young's modulus, which is beneficial to achieve low-frequency and small-size emission. The emission voltage response of the PMN-PT relaxor ferroelectric single crystal transducer can achieve nearly 150 dB, greatly improving the emission performance of the transducer and even the sonar system. However, the current research on relaxor ferroelectric single crystal transducers is only the same repetitive research as that of piezoelectric ceramic transducers driven in the 33 mode. The reduction of the characteristic size of the transducer comes from the performance advantages of the material, and the reduction of the characteristic size of the transducer has also reached the upper limit. The performance limit of the PMN-PT relaxor ferroelectric single crystal transducer has not been reached. Summary of the Invention

[0006] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source and a preparation method thereof. Two different piezoelectric materials are stacked, and the electrical signal is converted into a sound signal in different vibration modes, while improving the broadband performance and reducing the volume.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source, including a PMN-PT relaxor ferroelectric single crystal unit, a first bracket and a second bracket installed at both ends of the PMN-PT relaxor ferroelectric single crystal unit. A front radiation head is provided at one end of the first bracket away from the PMN-PT relaxor ferroelectric single crystal unit. A middle mass block, a first piezoelectric ceramic, a second piezoelectric ceramic, a tail mass block and a connecting member are sequentially provided at one end of the second bracket away from the PMN-PT relaxor ferroelectric single crystal unit. The connecting member passes through the inner holes of the tail mass block, the second piezoelectric ceramic, the first piezoelectric ceramic, and the middle mass block and is fixedly connected to the front radiation head.

[0008] Further, the PMN-PT relaxor ferroelectric single crystal unit includes a first PMN-PT relaxor ferroelectric single crystal, a second PMN-PT relaxor ferroelectric single crystal, a third PMN-PT relaxor ferroelectric single crystal, and a fourth PMN-PT relaxor ferroelectric single crystal whose heads and tails are not connected to each other. The first PMN-PT relaxor ferroelectric single crystal and the third PMN-PT relaxor ferroelectric single crystal are parallel to each other, and the second PMN-PT relaxor ferroelectric single crystal and the fourth PMN-PT relaxor ferroelectric single crystal are parallel to each other.

[0009] Further, a first limiting groove is provided on one side of the first bracket close to the second bracket, and a second limiting groove is provided on one side of the second bracket close to the first bracket. One end of the PMN-PT relaxor ferroelectric single crystal unit is fixedly connected in the first limiting groove, and the other end is installed in the second limiting groove.

[0010] Further, a first boss is provided on one side of the first bracket away from the second bracket, and a second boss is provided on one side of the second bracket away from the first bracket; a third limiting groove is provided on one side of the front radiation head close to the first bracket, and a fourth limiting groove is provided on one side of the middle mass block close to the second bracket. The first boss is fixedly connected in the third limiting groove, and the second boss is fixedly connected in the fourth limiting groove.

[0011] Further, single-crystal electrode sheets are provided on both sides of the first PMN-PT relaxor ferroelectric single crystal, the second PMN-PT relaxor ferroelectric single crystal, the third PMN-PT relaxor ferroelectric single crystal, and the fourth PMN-PT relaxor ferroelectric single crystal. The parallelism error between the single-crystal electrode sheet and the first PMN-PT relaxor ferroelectric single crystal is 0.05°.

[0012] Further, reserved holes are provided on the single-crystal electrode sheet for connecting bonding wires.

[0013] Further, the single-crystal electrode sheet is made of brass plated with silver; the thickness of the single-crystal electrode sheet is 0.1 ; the thickness of the silver plating layer of the single-crystal electrode sheet is 5 10 ; a plurality of through holes are provided on the single-crystal electrode sheet (35).

[0014] Further, ceramic electrode sheets are provided at the upper and lower ends of the first piezoelectric ceramic and the second piezoelectric ceramic. The parallelism error between the ceramic electrode sheet and the first piezoelectric ceramic is 0.05°.

[0015] Further, the ceramic electrode sheet is made of brass plated with silver; the thickness of the ceramic electrode sheet is 0.1 ; the thickness of the silver plating layer of the ceramic electrode sheet is 5 10 ; a plurality of through holes are provided on the ceramic electrode sheet.

[0016] A preparation method of a high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source, based on the above-mentioned high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source, includes the following steps: The PMN-PT relaxor ferroelectric single-crystal unit is fixedly connected to the first bracket at one end and the second bracket at the other end through a conductive epoxy resin adhesive; the first bracket is fixedly connected to the front radiation head through a conductive epoxy resin adhesive, and the second bracket is fixedly connected to the middle mass block through a conductive epoxy resin adhesive; the middle mass block is sequentially bonded to the first piezoelectric ceramic, the second piezoelectric ceramic, and the tail mass block; the connecting member passes through the inner holes of the tail mass block, the second piezoelectric ceramic, the first piezoelectric ceramic, and the middle mass block and is detachably connected to the front radiation head; the curing time of the conductive epoxy resin adhesive is 8 h, and the curing temperature is 80 °C.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects: A high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source according to the present invention uses two different piezoelectric materials, namely PMN-PT relaxor ferroelectric single crystal and PZT-4 piezoelectric ceramic. It converts electrical signals of different vibration modes into acoustic signals, greatly reducing the volume while improving the broadband performance, which is beneficial to the application of sonar systems carried by submarines, ships, and underwater unmanned vehicles.

[0018] A high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source according to the present invention connects a PMN-PT relaxor ferroelectric single crystal unit with a first piezoelectric ceramic, and the first piezoelectric ceramic is connected to a second piezoelectric ceramic. Compared with a single PMN-PT relaxor ferroelectric single crystal, the cost is lower.

[0019] A high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source according to the present invention uses alumina ceramics for the first bracket and the second bracket to ensure that the PMN-PT relaxor ferroelectric single crystal unit does not move or displace during operation, reducing the possibility of damage and improving the working stability and lifespan.

[0020] A high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source according to the present invention has multiple through holes provided on the single-crystal electrode sheet and the ceramic electrode sheet, and is fixedly connected to the PMN-PT relaxor ferroelectric single crystal unit, the first piezoelectric ceramic, or the second piezoelectric ceramic through a conductive epoxy resin adhesive. During the curing process of the conductive epoxy resin adhesive, tighter adhesion is achieved through the through holes.

[0021] For a high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source according to the present invention, the measured center frequency is 45 kHz, the maximum transmit voltage response is 157.84 dB, the maximum power is 48.27 W, the operating frequency band at -6 dB is 30 - 60 kHz, and the bandwidth is 30 kHz.

[0022] A high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source according to the present invention is composed of a PMN-PT relaxor ferroelectric single crystal unit, a first piezoelectric ceramic, and a second piezoelectric ceramic. Compared with the existing 144.46 dB maximum transmit voltage response and an operating frequency band of 30 - 50 kHz with a bandwidth of 20 kHz in the art, the maximum transmit voltage response is increased by 9.3% and the bandwidth is increased by 50%. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a structural diagram of a high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source according to the present invention; Figure 2 is a front view of a high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source according to the present invention; Figure 3 This is a top view of the PMN-PT relaxor ferroelectric single crystal unit in the embodiment of the present invention; Figure 4 This is a structural diagram of the first bracket, the PMN-PT relaxor ferroelectric single crystal unit, and the second bracket in the embodiment of the present invention; Figure 5 This is a cross-sectional view of the first bracket, the PMN-PT relaxor ferroelectric single crystal unit, and the second bracket in the embodiment of the present invention; Figure 6 This is a schematic structural diagram of the front radiation head and the first bracket in the embodiment of the present invention; Figure 7 This is a cross-sectional view of the front radiation head and the first bracket in the embodiment of the present invention; Figure 8 This is a schematic structural diagram of the second bracket and the middle mass in the embodiment of the present invention; Figure 9 This is a cross-sectional view of the second bracket and the middle mass in the embodiment of the present invention; Figure 10 This is a schematic structural diagram of the electrode sheet for the single crystal in the embodiment of the present invention; Figure 11 This is a front view of the third PMN-PT relaxor ferroelectric single crystal in the embodiment of the present invention; Figure 12 This is a schematic structural diagram of the PMN-PT relaxor ferroelectric single crystal unit in the embodiment of the present invention; Figure 13 This is a front view of the first piezoelectric ceramic and the second piezoelectric ceramic in the embodiment of the present invention; Figure 14 This is a cross-sectional view of the first piezoelectric ceramic and the second piezoelectric ceramic in the embodiment of the present invention; Figure 15 This is a top view of the first piezoelectric ceramic in the embodiment of the present invention; Figure 16 This is a schematic structural diagram of the positive and negative electrodes of the first PMN-PT relaxor ferroelectric single crystal in the embodiment of the present invention; Figure 17 This is a schematic structural diagram of the positive and negative electrodes of the electrode sheet for the ceramic in the embodiment of the present invention; Figure 18 This is a comparison diagram of the transmission performance and reception performance between a high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source of the present invention and other transducers.

[0024] Reference numerals: 1 - Front radiation head; 2 - First bracket; 3 - PMN-PT relaxor ferroelectric single crystal unit; 31 - First PMN-PT relaxor ferroelectric single crystal; 32 - Second PMN-PT relaxor ferroelectric single crystal; 33 - Third PMN-PT relaxor ferroelectric single crystal; 34 - Fourth PMN-PT relaxor ferroelectric single crystal; 35 - Electrode sheet for single crystal; 4 - Second bracket; 5 - Middle mass block; 6 - First piezoelectric ceramic; 61 - Electrode sheet for ceramic; 7 - Second piezoelectric ceramic; 8 - Tail mass block; 9 - Connecting piece. Detailed implementation manner

[0025] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0026] Embodiment 1 A high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source according to the present invention includes a PMN-PT relaxor ferroelectric single crystal unit 3, a first bracket 2 and a second bracket 4 installed at both ends of the PMN-PT relaxor ferroelectric single crystal unit 3. One end of the first bracket 2 far from the PMN-PT relaxor ferroelectric single crystal unit 3 is provided with a front radiation head 1. One end of the second bracket 4 far from the PMN-PT relaxor ferroelectric single crystal unit 3 is successively provided with a middle mass block 5, a first piezoelectric ceramic 6, a second piezoelectric ceramic 7, a tail mass block 8 and a connecting piece 9.

[0027] Conventional broadband transducers use the method of piezoelectric ceramic + piezoelectric ceramic to expand the working bandwidth, that is, a resonance peak is generated in each of the front and rear piezoelectric stacks. The trough between the two resonance peaks is superimposed within 6 dB. In order to generate two different peaks, the front and rear piezoelectric ceramics need a certain vibration direction size ratio, usually 1:2 or 1:3, which makes the overall size very large and does not meet the miniaturization requirements. For the combination of different materials, only the two resonance peaks need to be separated, and no size ratio is required. The thickness of the PMN-PT relaxor ferroelectric single crystal unit 3 of the present invention is close to that of the first piezoelectric ceramic 6 or the second piezoelectric ceramic 7, so the limitation of the size ratio is avoided. In addition, the use of the PMN-PT relaxor ferroelectric single crystal unit 3, the first piezoelectric ceramic 6, and the second piezoelectric ceramic 7 reduces the cost compared with single crystals and is convenient for popularization.

[0028] As Figure 1 shown, the transverse piezoelectric constant of the PMN-PT relaxor ferroelectric single crystal unit 3 is 1700 , the transverse electromechanical coupling coefficient is greater than or equal to 0.9, and the 32 mode with a relatively low resonant frequency can be excited when the longitudinal dimension is small, meeting the requirements of high emission performance and large working bandwidth. In the approximate frequency range of 0 - 60 kHz, the commercial broadband transducer achieved a maximum transmit voltage response of 140.02 dB, with a working frequency band of 28 - 46 kHz and a bandwidth of 18 kHz; the maximum transmit voltage response of the present invention is increased by 12.7% compared with the commercial broadband transducer, and the bandwidth is increased by 67%.

[0029] As Figure 2 shown, one end of the PMN-PT relaxor ferroelectric single crystal unit 3 is fixedly connected to the first bracket 2, and the other end is fixedly connected to the second bracket 4. The front end of the first bracket 2 is equipped with a front radiation head 1. The lower end of the second bracket 4 is sequentially connected with a middle mass block 5, a first piezoelectric ceramic 6, a second piezoelectric ceramic 7, and a tail mass block 8. In this embodiment, the connecting member 9 is a prestressed bolt, and the connecting member 9 passes through the tail mass block 8, the second piezoelectric ceramic 7, the first piezoelectric ceramic 6, the middle mass block 5 from bottom to top and is detachably connected to the front radiation head 1 to lock the entire transducer, ensuring that the front and rear vibrations are consistent during operation.

[0030] The first piezoelectric ceramic of the present invention is the first PZT-4 piezoelectric ceramic, and the second piezoelectric ceramic is the second PZT-4 piezoelectric ceramic.

[0031] As Figure 3 shown, the PMN-PT relaxor ferroelectric single crystal unit 3 is composed of a first PMN-PT relaxor ferroelectric single crystal 31, a second PMN-PT relaxor ferroelectric single crystal 32, a third PMN-PT relaxor ferroelectric single crystal 33, and a fourth PMN-PT relaxor ferroelectric single crystal 34 whose heads and tails are not connected to each other. Among them, the first PMN-PT relaxor ferroelectric single crystal 31 and the third PMN-PT relaxor ferroelectric single crystal 33 are parallel to each other, the second PMN-PT relaxor ferroelectric single crystal 32 and the fourth PMN-PT relaxor ferroelectric single crystal 34 are parallel to each other, and the first PMN-PT relaxor ferroelectric single crystal 31, the second PMN-PT relaxor ferroelectric single crystal 32, the third PMN-PT relaxor ferroelectric single crystal 33, and the fourth PMN-PT relaxor ferroelectric single crystal 34 are arranged in an open structure, having an extremely low frequency constant, an extremely high transverse piezoelectric coefficient, and an electromechanical coupling coefficient. Cooperating with the first piezoelectric ceramic 6 and the second piezoelectric ceramic 7, two resonant peaks with a relatively wide interval can be obtained when the longitudinal dimension is small, adjusting the driving ability and stiffness distribution between the PMN-PT relaxor ferroelectric single crystal unit 3 and the first piezoelectric ceramic 6 and the second piezoelectric ceramic 7 to achieve broadband emission.

[0032] As Figure 4 And as Figure 5As shown in the figure, a first limiting groove is provided on one side of the first bracket 2 close to the second bracket 4, and a second limiting groove is provided on one side of the second bracket 4 close to the first bracket 2. One end of the PMN-PT relaxor ferroelectric single crystal unit 3 is fixedly connected in the first limiting groove, and the other end is installed in the second limiting groove. The PMN-PT relaxor ferroelectric single crystal unit 3 is fixed to the first bracket 2 and the second bracket 4 by a conductive epoxy resin adhesive. Specifically, first, a conductive epoxy resin adhesive with a thickness of 0.05 - 0.1 mm is applied to the surface of the first limiting groove in contact with the PMN-PT relaxor ferroelectric single crystal unit 3, and then it is connected to the PMN-PT relaxor ferroelectric single crystal unit 3. The curing time of the conductive epoxy resin adhesive is 8 h, and the curing temperature is 80 °C. The second limiting groove on the second bracket 4 is fixed in the same way with a conductive epoxy resin adhesive.

[0033] As Figure 6 and as Figure 7 shown in the figure, a first boss is provided on one side of the first bracket 2 away from the second bracket 4, and a third limiting groove is provided on one side of the front radiation head 1 close to the first bracket 2. The first boss is adapted to the third limiting groove and is fixed by a conductive epoxy resin adhesive. The curing time is 8 h, and the curing temperature is 80 °C. As Figure 8 and as Figure 9 shown in the figure, a second boss is provided on one side of the second bracket 4 away from the first bracket 2, and a fourth limiting groove is provided on one side of the middle mass block 5 close to the second bracket 4. The second boss is adapted to the fourth limiting groove and is fixed by a conductive epoxy resin adhesive. It should be noted that the thickness of the conductive epoxy resin adhesive applied is 0.05 - 0.1 mm.

[0034] It should be noted that the first bracket 2 and the second bracket 4 are made of alumina ceramic brackets. The first PMN-PT relaxor ferroelectric single crystal 31, the second PMN-PT relaxor ferroelectric single crystal 32, the third PMN-PT relaxor ferroelectric single crystal 33, and the fourth PMN-PT relaxor ferroelectric single crystal 34 are fixed by the alumina ceramic brackets. The alumina ceramic has high hardness, good insulation performance, and thermodynamic characteristics similar to those of ferroelectric single crystals, which can effectively prevent the generation of thermal stress on the contact surface during operation; the surface is smooth, effectively solving the problem that single crystals are easily crushed by micro-protrusions on rough surfaces. It ensures that the PMN-PT relaxor ferroelectric single crystal unit 3 can only displace along the vibration direction, reducing the possibility of damage and improving the working stability and service life of the sensing element.

[0035] As Figure 10 and as Figure 12 shown in the figure, single crystal electrode plates 35 are provided on both sides of the first PMN-PT relaxor ferroelectric single crystal 31, the second PMN-PT relaxor ferroelectric single crystal 32, the third PMN-PT relaxor ferroelectric single crystal 33, and the fourth PMN-PT relaxor ferroelectric single crystal 34, and the error of parallelism is less than or equal to 0.05°. The single-crystal electrode sheet 35 is made of silver-plated brass and has a thickness of 0.1 and the thickness of the silver plating layer is 5 10 , as Figure 11 shown, a reserved hole is provided on the end face of the single-crystal electrode sheet 35 exceeding the third PMN-PT relaxor ferroelectric single crystal 33. The diameter of the reserved hole is 3 mm and is used for connecting the bonding wire. A plurality of through holes are provided on the end face connected to the third PMN-PT relaxor ferroelectric single crystal 33. The third PMN-PT relaxor ferroelectric single crystal 33 and the single-crystal electrode sheet 35 are fixed by a conductive epoxy resin adhesive. During the curing stage, in addition to flowing out from the periphery, the conductive epoxy resin adhesive also flows out from the through holes, which can better bond the other side of the single-crystal electrode sheet 35 and the third PMN-PT relaxor ferroelectric single crystal 33. The first PMN-PT relaxor ferroelectric single crystal 31, the second PMN-PT relaxor ferroelectric single crystal 32, and the fourth PMN-PT relaxor ferroelectric single crystal 34 are similar.

[0036] As Figure 13 and as Figure 14 shown, a ceramic electrode sheet 61 is provided between the first piezoelectric ceramic 6 and the second piezoelectric ceramic 7. Ceramic electrode sheets 61 are also provided at the upper end of the first piezoelectric ceramic 6 and the lower end of the second piezoelectric ceramic 7. The ceramic electrode sheet 61 is made of silver-plated brass and has a thickness of 0.1 and the thickness of the silver plating layer is 5 10 .

[0037] It should be noted that the first PMN-PT relaxor ferroelectric single crystal 31, the second PMN-PT relaxor ferroelectric single crystal 32, the third PMN-PT relaxor ferroelectric single crystal 33, and the fourth PMN-PT relaxor ferroelectric single crystal 34 are the same in shape. The difference between the ceramic electrode sheet 61 and the first PMN-PT relaxor ferroelectric single crystal 31 lies in the different shapes. The first PMN-PT relaxor ferroelectric single crystal 31 is rectangular, and the ceramic electrode sheet 61 is circular.

[0038] As Figure 15 shown, a plurality of through holes are provided on the ceramic electrode sheet 61. The ceramic electrode sheet 61 and the first piezoelectric ceramic 6 as well as the second piezoelectric ceramic 7 are fixed by a conductive epoxy resin adhesive.

[0039] The diameter of the through holes is 1 mm, one is drilled every 45°, 8 in each circle, and a total of 16. No holes are drilled at the positions corresponding to the first piezoelectric ceramic 6 and the second piezoelectric ceramic 7.

[0040] The first piezoelectric ceramic 6 and the second piezoelectric ceramic 7 have positive and negative poles, as Figure 17As shown, when correctly connected to the circuit, it vibrates in the direction of the positive electrode. If connected reversely, it is similar to a diode not conducting in the reverse direction and does not produce vibration. The transducer operates with alternating current, which is a sine wave with positive and negative values, that is, the voltage direction changes periodically. Therefore, an even number of piezoelectric ceramics or piezoelectric components are required, grouped in pairs with opposite polarities (when stacked, it is the same-pole contact, without different-pole contact), so as to always ensure that at any time, there is a piezoelectric element vibrating in the set direction.

[0041] The positive and negative electrodes of the first PMN-PT relaxor ferroelectric single crystal 31, the second PMN-PT relaxor ferroelectric single crystal 32, the third PMN-PT relaxor ferroelectric single crystal 33, and the fourth PMN-PT relaxor ferroelectric single crystal 34 are as Figure 16 shown, grouped in pairs with opposite polarities to each other, ensuring that when the first PMN-PT relaxor ferroelectric single crystal 31 and the third PMN-PT relaxor ferroelectric single crystal 33 vibrate, the second PMN-PT relaxor ferroelectric single crystal 32 and the fourth PMN-PT relaxor ferroelectric single crystal 34 do not vibrate, and when the second PMN-PT relaxor ferroelectric single crystal 32 and the fourth PMN-PT relaxor ferroelectric single crystal 34 vibrate, the first PMN-PT relaxor ferroelectric single crystal 31 and the third PMN-PT relaxor ferroelectric single crystal 33 do not vibrate.

[0042] For a high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source in the present invention, the center frequency of the physical test is 45 kHz, the maximum transmit voltage response is 157.84 dB, the maximum power is 48.27 W, the operating frequency band at -6 dB is 30 - 60 kHz, and the bandwidth is 30 kHz. -6 dB is the frequency range corresponding to within 6 dB less than the maximum transmit voltage response. When the transmit voltage response corresponding to this frequency is 6 dB less than the maximum transmit voltage response, it means that the power at this time is 1 / 4 of the maximum power, that is, the quarter-power point, which is considered the minimum limit for the effective operation of the transducer.

[0043] As Figure 18As shown in the figure, the figure below shows the comparison of the transmitting and receiving performances between a high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source of the present invention and other transducers. The other transducers include a piezoelectric ceramic dual-excitation transducer, a commercial high-performance broadband transducer, and transducers fabricated by other researchers in the field. The maximum receiving sensitivity of the transducers fabricated by other researchers in the field is about -180 dB, and the working bandwidth is about 12 kHz. The commercial high-performance broadband transducer sacrifices a certain amount (about 3-5%) of receiving sensitivity but expands the receiving bandwidth by about 20-30% compared with the former. The piezoelectric ceramic dual-excitation transducer without adapting and optimizing for the receiving performance is significantly inferior in both bandwidth and maximum receiving sensitivity. The transmitting and receiving performances of the ceramic-single crystal hybrid excitation transducer designed in this paper are compared with a series of transducers. The maximum transmitting voltage response is increased by 10-15%, the bandwidth is increased by 40-50% (-6 dB), and the maximum receiving sensitivity is increased by 5-10% under the same working bandwidth, showing significant performance advantages. Specifically, as shown in Table 1 and Table 2. Table 1 is the comparison of transmitting performances, and Table 2 is the comparison of receiving performances.

[0044] Table 1

[0045] Table 2

[0046] Example 2 A preparation method of a high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source, comprising the following steps: one end of a PMN-PT relaxor ferroelectric single crystal unit 3 is fixedly connected to a first bracket 2 through a conductive epoxy resin adhesive, and the other end is fixedly connected to a second bracket 4; the first bracket 2 is fixedly connected to a front radiator 1 through a conductive epoxy resin adhesive, and the second bracket 4 is fixedly connected to a middle mass 5 through a conductive epoxy resin adhesive; the middle mass 5 is successively bonded to a first piezoelectric ceramic 6, a second piezoelectric ceramic 7, and a tail mass 8; a connecting member 9 passes through the inner holes of the tail mass 8, the second piezoelectric ceramic 7, the first piezoelectric ceramic 6, and the middle mass 5 and is detachably connected to the front radiator 1; the curing time of the conductive epoxy resin adhesive is 8 h, and the curing temperature is 80 °C.

[0047] Specifically, one end of the PMN-PT relaxor ferroelectric single crystal unit 3 is fixedly connected to the first bracket 2 through a conductive epoxy adhesive to ensure a tight connection and good electrical conductivity. The other end is also fixedly connected to the second bracket 4 using a conductive epoxy adhesive. The first bracket 2 is fixedly connected to the front radiator 1 through a conductive epoxy adhesive to ensure that sound waves can be efficiently transmitted from the PMN-PT relaxor ferroelectric single crystal unit 3 to the front radiator 1 and then radiated out. The middle mass 5 is bonded to the first piezoelectric ceramic 6 and the second piezoelectric ceramic 7 in sequence through a conductive epoxy adhesive to form a composite excitation structure. Utilizing the piezoelectric effect of the PZT-4 piezoelectric ceramic, the frequency response range of the transducer is further broadened. The tail mass 8 is bonded to the other end of the second piezoelectric ceramic 7 through a conductive epoxy adhesive to stabilize the rear end of the entire composite excitation structure. A connecting member 9 passes through the inner holes of the tail mass 8, the second piezoelectric ceramic 7, the first piezoelectric ceramic 6, and the middle mass 5 and is detachably connected to the front radiator 1, ensuring the stability and reliability of the entire transducer structure.

[0048] It should be noted that the terms "first", "second", etc. in the description, claims, and above-mentioned drawings of the present invention are used to distinguish similar objects and do not necessarily have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

Claims

1. A high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source, characterized in that: It includes a PMN-PT relaxor ferroelectric single-crystal unit (3), a first bracket (2) and a second bracket (4) installed at both ends of the PMN-PT relaxor ferroelectric single-crystal unit (3). One end of the first bracket (2) away from the PMN-PT relaxor ferroelectric single-crystal unit (3) is provided with a front radiation head (1), and the other end of the second bracket (4) away from the PMN-PT relaxor ferroelectric single-crystal unit (3) is sequentially provided with a middle mass block (5), a first piezoelectric ceramic (6), a second piezoelectric ceramic (7), a tail mass block (8) and a connecting member (9); The connecting member (9) passes through the inner holes of the tail mass block (8), the second piezoelectric ceramic (7), the first piezoelectric ceramic (6), and the middle mass block (5) and is fixedly connected to the front radiation head (1).

2. The high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source according to claim 1, characterized in that: The PMN-PT relaxor ferroelectric single-crystal unit (3) includes a first PMN-PT relaxor ferroelectric single crystal (31), a second PMN-PT relaxor ferroelectric single crystal (32), a third PMN-PT relaxor ferroelectric single crystal (33) and a fourth PMN-PT relaxor ferroelectric single crystal (34) whose heads and tails are not connected to each other; The first PMN-PT relaxor ferroelectric single crystal (31) and the third PMN-PT relaxor ferroelectric single crystal (33) are parallel to each other, and the second PMN-PT relaxor ferroelectric single crystal (32) and the fourth PMN-PT relaxor ferroelectric single crystal (34) are parallel to each other.

3. The high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source according to claim 1, characterized in that: A first limiting groove is provided on one side of the first bracket (2) close to the second bracket (4), a second limiting groove is provided on one side of the second bracket (4) close to the first bracket (2), one end of the PMN-PT relaxor ferroelectric single-crystal unit (3) is fixedly connected in the first limiting groove, and the other end is installed in the second limiting groove.

4. The high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source according to claim 3, characterized in that: A first boss is provided on one side of the first bracket (2) away from the second bracket (4), and a second boss is provided on one side of the second bracket (4) away from the first bracket (2); A third limiting groove is provided on one side of the front radiation head (1) close to the first bracket (2), a fourth limiting groove is provided on one side of the middle mass block (5) close to the second bracket (4), the first boss is fixedly connected in the third limiting groove, and the second boss is fixedly connected in the fourth limiting groove.

5. The high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source according to claim 2, characterized in that: On both sides of the first PMN-PT relaxor ferroelectric single crystal (31), the second PMN-PT relaxor ferroelectric single crystal (32), the third PMN-PT relaxor ferroelectric single crystal (33), and the fourth PMN-PT relaxor ferroelectric single crystal (34), single-crystal electrode plates (35) are provided, and the parallelism error between the single-crystal electrode plate (35) and the first PMN-PT relaxor ferroelectric single crystal (31) is 0.05°.

6. The high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source according to claim 5, characterized in that: The single-crystal electrode plate (35) is provided with a reserved hole for connecting a bonding wire.

7. The high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source according to claim 6, characterized in that: The single-crystal electrode plate (35) is made of brass plated with silver; The thickness of the single-crystal electrode sheet (35) is 0.1 ; The silver plating thickness of the single crystal electrode sheet (35) is 5 10 ; A plurality of through holes are provided in the single crystal electrode plate (35).

8. The high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source according to claim 1, wherein: The upper and lower ends of the first piezoelectric ceramic (6) and the second piezoelectric ceramic (7) are provided with ceramic electrode plates (61), and the parallelism error between the ceramic electrode plates (61) and the first piezoelectric ceramic (6) is 0.05°.

9. The high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source according to claim 8, wherein: The ceramic electrode plate (61) is made of silver-plated brass; The thickness of the ceramic electrode sheet (61) is 0.1 ; The silver plating thickness of the ceramic electrode sheet (61) is 5 10 ; A plurality of through holes are provided in the ceramic electrode plate (61).

10. A method for preparing a high-performance broadband intermediate-frequency transducer driven by a hybrid excitation source, based on the high-performance broadband intermediate-frequency transducer driven by the hybrid excitation source according to any one of claims 1-9, characterized in that, It includes the following steps: The PMN-PT relaxor ferroelectric single crystal unit (3) is fixedly connected to the first bracket (2) at one end and the second bracket (4) at the other end through a conductive epoxy adhesive; The first bracket (2) is fixedly connected to the front radiation head (1) through a conductive epoxy adhesive, and the second bracket (4) is fixedly connected to the middle mass block (5) through a conductive epoxy adhesive; The middle mass block (5) is sequentially bonded to the first piezoelectric ceramic (6), the second piezoelectric ceramic (7), and the tail mass block (8); The connecting member (9) passes through the inner holes of the tail mass block (8), the second piezoelectric ceramic (7), the first piezoelectric ceramic (6), and the middle mass block (5) and is detachably connected to the front radiation head (1); The curing time of the conductive epoxy adhesive is 8 h, and the curing temperature is 80 °C.

Images