Array ultrasonic transducer with high-frequency domain bandwidth and sensitivity

Abstract

The invention relates to an array ultrasonic transducer with high-frequency domain bandwidth and sensitivity. The back-lining sound absorption device comprises a back-lining sound absorption unit and an array element array arranged on the back-lining sound absorption unit, and the array element array comprises at least one array element unit; any array element unit at least comprises an array element main device for ultrasonic transduction and an acoustic amplification lamination layer matched with the array element main device, and the array element main device comprises a piezoelectric unit adjacent to the backing sound absorption unit; the acoustic amplification lamination layer is located between the piezoelectric unit and the backing sound absorption unit, and the acoustic amplification lamination layer at least comprises a high-impedance area, a full-transmission area and a low-impedance area which are arranged in sequence in the direction from the piezoelectric unit to the backing sound absorption unit. The method has high frequency domain bandwidth and sensitivity, and can effectively improve the ultrasonic imaging quality.

Description

Technical Field

[0001] The present invention relates to an ultrasonic transducer, in particular to an array ultrasonic transducer with high-frequency bandwidth and high sensitivity. Background Art

[0002] Ultrasonic imaging, due to its real-time, efficient, and radiation-free nature, has been widely used in medical diagnosis, industrial non-destructive testing, distance measurement, obstacle avoidance radar, and other fields. The ultrasonic transducer is a key component of ultrasonic imaging systems. It converts electrical excitation signals into acoustic signals that can be transmitted to the medium under test, and can receive echo signals reflected by different test media. These echo signals are then converted into electrical signals, which are then processed and analyzed by the back-end imaging system to achieve the purpose of ultrasonic imaging. Therefore, the electrical and acoustic performance of the ultrasonic transducer will greatly affect the resolution, clarity, and penetration depth of ultrasonic imaging.

[0003] Traditional array ultrasonic transducers are generally composed of a piezoelectric layer, an acoustic matching layer, a backing sound-absorbing layer, and a circuit board. The piezoelectric layer is the core component of the transducer. It receives electrical pulse excitation to form an ultrasonic signal on the surface of the piezoelectric layer. Currently, the material of the piezoelectric layer can be PZT ceramic, PMN-PT single crystal, lead-free piezoelectric ceramic, or a piezoelectric-based composite. Generally, the acoustic impedance of the piezoelectric layer is high, usually greater than 20 MRayls, while the acoustic impedance of the medium to be measured is usually low. Therefore, an acoustic matching layer is required to transmit the forward ultrasonic energy to the medium to be measured as much as possible, thereby improving the transceiver sensitivity of the ultrasonic transducer.

[0004] The acoustic impedance of the acoustic matching layer lies between the acoustic impedance of the piezoelectric layer and the acoustic impedance of the measured medium. Its specific value needs to be calculated based on different theoretical models. To minimize the reflection of the ultrasonic signal generated by the piezoelectric layer backward into the measured medium in front, thereby avoiding the generation of clutter and image artifacts, a backing sound-absorbing layer is typically applied to the back of the piezoelectric layer. This backing sound-absorbing layer absorbs unnecessary clutter signals, maximizing the absorption of the acoustic signal transmitted backward from the piezoelectric layer. This reduces the pulse width of the ultrasonic signal transmitted forward, thereby improving the frequency domain bandwidth and the vertical resolution of the image.

[0005] Currently, while the backing sound-absorbing layer of conventional array ultrasonic transducers can absorb clutter and increase the frequency bandwidth, it also absorbs the ultrasonic energy emitted backward by the piezoelectric layer, thereby reducing the transducer's transmit and receive sensitivity. This indicates that conventional ultrasonic transducers experience a mutually restrictive relationship between sensitivity and frequency bandwidth, making it impossible to simultaneously achieve a large frequency bandwidth and high sensitivity. Consequently, the design of ultrasonic transducers typically requires a balanced consideration, hindering the further development of high-quality imaging ultrasound systems. Summary of the Invention

[0006] The purpose of the present invention is to overcome the deficiencies in the prior art and provide an array ultrasonic transducer with high frequency bandwidth and sensitivity, which has high frequency domain bandwidth and sensitivity and can effectively improve the quality of ultrasonic imaging.

[0007] According to the technical solution provided by the present invention, an array ultrasonic transducer with high-frequency bandwidth and sensitivity, the array ultrasonic transducer includes a backing sound absorbing unit and an array element array arranged on the backing sound absorbing unit, wherein:

[0008] The array element array includes at least one array element unit;

[0009] Any array element unit at least includes an array element main component for ultrasonic transduction and an acoustic amplification stack adapted to the array element main component, wherein:

[0010] The array element main component includes a piezoelectric unit adjacent to a backing sound absorbing unit;

[0011] The acoustic amplification stack is located between the piezoelectric unit and the backing sound absorption unit, wherein, along the direction from the piezoelectric unit to the backing sound absorption unit, the acoustic amplification stack includes at least a high impedance region, a fully transparent region, and a low impedance region arranged in sequence.

[0012] The ultrasonic signal generated by the piezoelectric unit and propagating toward the backing sound absorbing unit is reflected by the high impedance area, and the ultrasonic signal not reflected by the high impedance area is fully transmitted to the low impedance area through the fully transparent area, so that the fully transmitted ultrasonic signal is fully absorbed by the low impedance area and / or the backing sound absorbing unit.

[0013] The full transmission area includes a plurality of high-impedance unit bodies and low-impedance unit bodies corresponding to the high-impedance unit bodies, wherein:

[0014] The high-impedance unit body and the low-impedance unit body are embedded in each other and in close contact.

[0015] On the cross section of the fully transparent region, the high-impedance unit cells and the low-impedance unit cells are at least arranged in a continuous alternating pattern, and the alternating arrangement direction of the high-impedance unit cells and the low-impedance unit cells is perpendicular to the direction from the high-impedance region to the low-impedance region;

[0016] From the high impedance area to the low impedance area, the acoustic impedance of the high impedance unit body gradually decreases;

[0017] From the low impedance area to the high impedance area, the acoustic impedance of the low impedance unit body tends to gradually decrease.

[0018] The high impedance unit cell and the low impedance unit cell have the same cross-sectional shape, wherein:

[0019] At least one inclined non-parallel surface structure is provided on the corresponding cross sections of the high-impedance unit body and the low-impedance unit body, wherein the inclined non-parallel surface structure is non-parallel to the high-impedance region and the low-impedance region;

[0020] For any inclined non-parallel surface structure, the angle α between the inclined non-parallel surface structure and the bottom surface of the unit cross section of the corresponding cross section of the high-impedance unit body or the low-impedance unit body is 15° to 60°;

[0021] In the fully transparent region, the high-impedance unit body and the low-impedance unit body form a mutually plug-in connection state, wherein, when the high-impedance unit body and the low-impedance unit body are plug-in connected, the outer surface of the inclined non-parallel surface structure formed by the high-impedance unit body is in close contact with the outer surface of the corresponding inclined non-parallel surface structure formed by the corresponding low-impedance unit body.

[0022] The thickness of the fully transparent area is λ2 / 8 to λ2 / 4, wherein λ2 is the equivalent wavelength of the equivalent sound velocity of the ultrasonic wave passing through the fully transparent area at the center frequency.

[0023] The cross-sectional shapes of the high-impedance unit body and the low-impedance unit body include triangle, trapezoid, arc or wedge shape.

[0024] The high impedance region in the acoustic amplification stack contacts the piezoelectric unit, and the low impedance region in the acoustic amplification stack contacts the backing sound absorption unit, wherein:

[0025] The acoustic impedance of the high impedance region is at least twice the acoustic impedance of the piezoelectric unit;

[0026] The acoustic impedance of the low-impedance unit is at most 1 / 10 of the acoustic impedance of the piezoelectric unit.

[0027] The high-impedance unit body is prepared on the high-impedance area, and the high-impedance unit body and the high-impedance area are prepared and formed by an integrated molding process;

[0028] The low-impedance unit body is prepared on the low-impedance area, and the low-impedance unit body and the low-impedance area are prepared and formed by an integrated molding process;

[0029] When preparing the acoustic amplification stack, a high-impedance region and high-impedance unit bodies distributed on the high-impedance region are first prepared. Thereafter, a low-impedance unit body and a corresponding low-impedance region are prepared on the high-impedance region, wherein the prepared low-impedance unit body is embedded in and in close contact with the high-impedance unit body.

[0030] When preparing the acoustic amplification stack, the preparation method includes:

[0031] Providing a high-impedance substrate and patterning the high-impedance substrate to generate a high-impedance region and form a plurality of high-impedance unit bodies on the high-impedance region after patterning;

[0032] Applying bonding connections to at least the high-resistance unit body,

[0033] A low-impedance unit body and a low-impedance region are formed on the high-impedance region.

[0034] At least the corresponding surfaces of the low-resistance unit body and the high-resistance unit body are locally heated to form a bonding connection layer after the local heating, and the formed bonding connection layer is used to at least make the low-resistance unit body and the high-resistance unit body closely contact each other.

[0035] The high-impedance substrate is made of a high-impedance material, and the high-impedance material used by the high-impedance substrate includes metal or rigid dielectric material, wherein:

[0036] When the high-resistance substrate is made of metal, the patterning method for the high-resistance substrate at least includes ablation.

[0037] For any array element unit, when the array element unit is working, the piezoelectric unit is in a piezoelectric resonance mode based on the high impedance region within the array element unit, wherein:

[0038] When the piezoelectric unit is in the piezoelectric resonance mode, a resonant oscillation in a free-fixed boundary state is formed. The thickness of the piezoelectric unit is 0.25λ3 to 0.5λ3, where λ3 is the wavelength of the ultrasonic wave passing through the piezoelectric unit at the center frequency.

[0039] The array element main component further includes a matching unit located on the piezoelectric unit, wherein:

[0040] The matching unit includes a matching first unit layer located on the piezoelectric unit and a matching second unit layer located on the matching first unit layer;

[0041] The acoustic impedance of the first unit layer is matched to be greater than the acoustic impedance of the second unit layer.

[0042] The advantages of the present invention are as follows: an acoustic amplification layer is arranged between the piezoelectric unit and the backing sound absorbing unit. Along the direction from the piezoelectric unit to the backing sound absorbing unit, the acoustic amplification layer comprises at least a high impedance region, a fully transparent region and a low impedance region arranged in sequence.

[0043] The ultrasonic signal generated by the piezoelectric unit and propagating toward the backing sound-absorbing unit is reflected by the high-impedance area, and the ultrasonic signal not reflected by the high-impedance area is fully transmitted to the low-impedance area through the fully-transmitting area, so that the fully-transmitted ultrasonic signal is fully absorbed by the low-impedance area and / or the backing sound-absorbing unit. This enables the array ultrasonic transducer to have a high frequency domain bandwidth and sensitivity, and can effectively improve the quality of ultrasonic imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 Schematic diagram of an embodiment of an existing array ultrasonic transducer.

[0045] Figure 2 Schematic diagram of an embodiment of the array ultrasonic transducer of the present invention.

[0046] Figure 3 Schematic diagram of an embodiment of the acoustic amplification stack of the present invention.

[0047] Figure 4 It is a cross-sectional schematic diagram of an embodiment of a high-impedance unit body and a low-impedance unit body of the present invention.

[0048] Figure 5 for Figure 2 A top view of an embodiment of an array ultrasound transducer.

[0049] Figure 6 for Figure 2 A side view of an embodiment of an array ultrasound transducer.

[0050] Figure 7 A schematic diagram comparing an embodiment of FEM simulation data of pulse echo performance of an array ultrasonic transducer unit of the present invention and a conventional array ultrasonic transducer.

[0051] Figure 8 To show Figure 7 A schematic diagram of an embodiment comparison of calculation results of FEM simulation data.

[0052] Explanation of the reference numerals: 100 - array ultrasonic transducer device, 102 - array element structure, 106 - matching layer, 108 - structural insulator, 110 - piezoelectric layer, 112 - backing sound absorption layer, 200 - array ultrasonic transducer unit, 202 - array element unit, 204 - matching second unit layer, 206 - matching first unit layer, 208 - main component insulator, 210 - pressure unit, 214 - acoustic amplification stack, 216 - backing sound absorption unit, 218 - high impedance unit body, 220 - low impedance unit body, 222 - inclined non-parallel surface structure, 224 - unit body cross-section bottom surface, 302 - first connecting circuit board, 304 - second connecting circuit board, 402 - array element connecting line, 502 - protective layer. DETAILED DESCRIPTION

[0053] The present invention will be further described below with reference to specific drawings and embodiments.

[0054] Figure 1 An embodiment of an existing array ultrasonic transducer is shown in FIG. Figure 1 FIG. 1 shows an embodiment of an arrayed ultrasonic transducer device 100 . In the figure, the arrayed ultrasonic transducer device 100 includes a backing sound-absorbing layer 112 , on which array element structures 102 are arranged. Adjacent array element structures 102 are isolated from each other by structural isolators 108 , wherein the structural isolators 108 can generally be made of potting glue.

[0055] Generally, one array element structure 102 can form an array element of an array ultrasonic transducer, that is, the array element structure 102 can realize the transmission and reception of ultrasonic signals. Figure 1 In the embodiment, the array element structure 102 includes a piezoelectric layer 110 disposed on a backing sound-absorbing layer 112, and a matching layer 106 disposed on the piezoelectric layer 110. Specifically, the piezoelectric layer 110 has a thickness of approximately half a wavelength. During resonance, ultrasonic signals are generated in both forward and backward directions. The forward ultrasonic signal is transmitted to the matching layer 106, while the backward ultrasonic signal is transmitted to the backing sound-absorbing layer 112. To allow the ultrasonic signal to better penetrate the matching layer 106, its thickness is typically 0.25λ1, where λ1 is the longitudinal wavelength of the sound wave passing through the matching layer 106 at the center frequency. The acoustic impedance of the backing sound-absorbing layer 112 can affect the bandwidth and sensitivity of the arrayed ultrasonic transducer device 100, but it does not guarantee that the arrayed ultrasonic transducer device 100 can simultaneously achieve a large frequency bandwidth and high sensitivity.

[0056] As can be seen from the above description, the array ultrasonic transducer device 100 in the prior art is generally unable to simultaneously obtain a large frequency domain bandwidth and high sensitivity due to the form adopted by the array element structure 102. In other words, it can generally only choose a compromise between a large frequency domain bandwidth and high sensitivity.

[0057] In order to enable the arrayed ultrasonic transducer to have both high frequency domain bandwidth and sensitivity, so as to effectively improve the quality of ultrasonic imaging, the present invention provides an arrayed ultrasonic transducer with high frequency domain bandwidth and sensitivity. Specifically, the arrayed ultrasonic transducer includes a backing sound absorbing unit 216 and an array element array provided on the backing sound absorbing unit 216, wherein:

[0058] The array element array includes at least one array element unit 202;

[0059] Any array element unit 202 at least includes an array element main component for ultrasonic transduction and an acoustic amplification stack 214 adapted to the array element main component, wherein:

[0060] The array element main component includes a piezoelectric unit 210 adjacent to a backing sound absorbing unit 216;

[0061] The acoustic amplification stack 214 is located between the piezoelectric unit 210 and the backing sound absorbing unit 216. In the direction from the piezoelectric unit 210 to the backing sound absorbing unit 216, the acoustic amplification stack 214 includes at least a high-impedance region, a fully transparent region, and a low-impedance region arranged in sequence.

[0062] The ultrasonic signal generated by the piezoelectric unit 210 and propagating toward the backing sound absorbing unit 216 is reflected by the high impedance area, and the ultrasonic signal not reflected by the high impedance area is fully transmitted to the low impedance area through the fully transparent area, so that the fully transmitted ultrasonic signal is fully absorbed by the low impedance area and / or the backing sound absorbing unit 216.

[0063] It should be noted that the high frequency bandwidth of the present invention is the large frequency bandwidth mentioned above. The working principle of the array ultrasonic transducer of the present invention should be consistent with the working principle of the existing commonly used ultrasonic transducers. Therefore, the array ultrasonic transducer of the present invention should include a backing sound absorbing unit 216 and an array element array arranged on the backing sound absorbing unit 216, wherein the backing sound absorbing unit 216 is used to absorb clutter signals. The function of the backing sound absorbing unit 216 is consistent with the existing technology, such as the backing sound absorbing unit 216 and the array element array arranged on the backing sound absorbing unit 216. Figure 1 The function of the backing sound absorbing layer 112 is consistent.

[0064] In order to form an array ultrasonic transducer, an array element array should be provided on the backing sound absorbing unit 216. Generally, the array element array includes at least one array element unit 202. Figure 2 An embodiment of the array ultrasonic transducer of the present invention is shown in FIG. Figure 2 In the figure, the array element array includes three array element units 202, and adjacent array element units 202 are isolated from each other by main component isolation members 208, wherein the main component isolation members 208 can be in the form of potting glue, etc., that is, the function of the main component isolation members 208 is consistent with that of the structural isolation members 108. For details, please refer to the description of the structural isolation members 108, etc.

[0065] Generally, the array element units 202 in the array element array may preferably adopt the same structural form. Specifically, the array element unit 202 should include an array element main component, through which ultrasonic transduction can be achieved. Ultrasonic transduction is the transceiver processing of ultrasonic signals mentioned in the background technology, that is, the array element main component is the main body of the array element unit 202. Therefore, it can be seen that the array element main component can adopt Figure 1 The structure shown in the figure can also be in other forms. It should be understood that in order to achieve ultrasonic transduction, the main element of the array should at least include a piezoelectric unit 210, the piezoelectric unit 210 is adjacent to the backing sound absorption unit 216 in the main element of the array, and the piezoelectric unit 210 and the backing sound absorption unit 216 are connected. Figure 1 The piezoelectric layer 110 in has the same function, and the details can be referred to the corresponding description above.

[0066] In order to enable the arrayed ultrasonic transducer to have both high frequency bandwidth and sensitivity, in one embodiment of the present invention, an acoustic amplification stack 214 is further provided in each array element unit 202. The acoustic amplification stack 214 is located between the pressure unit 210 and the backing sound absorption unit 216. Figure 2 As shown, the acoustic amplification stack 214 adopts a laminated composite structure. Generally, the acoustic amplification stack 214 may include at least a high impedance region, a fully transparent region, and a low impedance region, and the high impedance region, the fully transparent region, and the low impedance region are arranged in sequence. Figure 3 An embodiment of an acoustic amplification stack 214 is shown in FIG. Figure 3 In the figure, the area corresponding to t1 is the high impedance area, the area corresponding to t2 is the full transmission area, and the area corresponding to t3 is the low impedance area. As can be seen from the figure, the full transmission area is in contact with the high impedance area and the low impedance area.

[0067] As can be seen from the above description, when the piezoelectric element 210 is in operation, it generates ultrasonic signals in both forward and backward directions. Specifically, the forward ultrasonic signal propagates toward the array element main component, while the backward ultrasonic signal propagates toward the backing sound-absorbing element 216. In other words, the ultrasonic signal propagating toward the backing sound-absorbing element 216 first passes through the acoustic amplification stack 214. In a specific implementation, the high-impedance region is adjacent to the piezoelectric element 210, while the low-impedance region is adjacent to the backing sound-absorbing element 216. It should be noted that when the ultrasonic signal propagates to the acoustic amplification stack 214, the acoustic impedance of the high-impedance region can be used to maximize the reflection of the ultrasonic signal, thereby achieving co-directional superposition with the ultrasonic signal transmitted forward by the piezoelectric element 210, thereby increasing the sensitivity of the array ultrasonic transducer.

[0068] It is understandable that the high-impedance region cannot reflect all ultrasonic signals, meaning that some unreflected ultrasonic signals may exist. In this case, these unreflected ultrasonic signals will continue to propagate toward the backing sound-absorbing unit 216. In specific implementations, ultrasonic signals that are unreflected and propagate toward the backing sound-absorbing unit 216 will pass through the fully-transmitting region. At this point, the ultrasonic signals will be transmitted to the low-impedance region. In other words, the ultrasonic signals that have passed through the fully-transmitting region will not be reflected again by the high-impedance region but will instead be fully transmitted to the low-impedance region. This allows the low-impedance region and / or the backing sound-absorbing unit 216 to absorb the ultrasonic signals that have passed through the fully-transmitting region, thereby preventing the generation of parasitic noise and increasing the frequency domain bandwidth of the arrayed ultrasonic transducer, thereby providing the arrayed ultrasonic transducer with a large frequency domain bandwidth.

[0069] As can be seen from the above description, the high impedance region can be used to reflect the ultrasonic signal, and the low impedance region can be used to absorb the ultrasonic signal. Since the acoustic impedance of the high impedance region is significantly different from that of the low impedance region, when the high impedance region is in direct contact with the low impedance region, the acoustic impedance difference at the contact interface is large and discontinuous. At this time, the ultrasonic signal that is not reflected by the high impedance region will repeatedly reflect and transmit at the contact interface, thereby generating parasitic noise. The generated parasitic noise will reduce the frequency domain bandwidth of the array ultrasonic transducer. In one embodiment of the present invention, the high impedance region and the low impedance region are separated by a fully transparent region, that is, the high impedance region and the low impedance region will not be in direct contact. After the ultrasonic signal that is not reflected by the high impedance region enters the low impedance region through the fully transparent region, the characteristics of the fully transparent region can be used to prevent the ultrasonic signal from propagating to the piezoelectric unit 210, thereby avoiding the generation of parasitic noise.

[0070] In one embodiment of the present invention, the high impedance region in the acoustic amplification stack 214 contacts the piezoelectric unit 210, and the low impedance region in the acoustic amplification stack 214 contacts the backing sound absorbing unit 216, wherein:

[0071] The acoustic impedance of the high-impedance region is at least twice the acoustic impedance of the piezoelectric unit 210;

[0072] The acoustic impedance of the low-impedance unit is at most 1 / 10 of the acoustic impedance of the piezoelectric unit 210 .

[0073] Figure 2 In the embodiment shown in FIG, the acoustic amplification stack 214 is in contact with the piezoelectric unit 210 and the backing sound absorption unit 216. At this time, the high impedance region in the acoustic amplification stack 214 is in contact with the piezoelectric unit 210, and the low impedance region in the acoustic amplification stack 214 is in contact with the backing sound absorption unit 216.

[0074] To maximize the reflection of the ultrasonic signal generated by the piezoelectric unit 210, the acoustic impedance of the high-impedance region can be set to twice the acoustic impedance of the piezoelectric unit 210. That is, the acoustic impedance of the high-impedance region can be twice or more the corresponding acoustic impedance of the piezoelectric unit 210. To absorb the ultrasonic signal after passing through the fully transparent region, the acoustic impedance of the low-impedance unit is at most 1 / 10 of the acoustic impedance of the piezoelectric unit 210.

[0075] In specific implementations, after selecting the piezoelectric unit 210 based on the characteristics of the array element 202, the corresponding acoustic impedances of the high-impedance and low-impedance regions within the acoustic amplification stack 214 can be determined. It will be appreciated that ultrasonic signals passing through the fully transparent region can be absorbed by the low-impedance region and / or the backing sound-absorbing unit 216.

[0076] In one embodiment of the present invention, the fully transparent region includes a plurality of high-impedance unit bodies 218 and low-impedance unit bodies 220 corresponding to the high-impedance unit bodies 218, wherein:

[0077] The high-impedance unit 218 and the low-impedance unit 220 are embedded in each other and in close contact.

[0078] On the cross section of the fully transparent region, the high-impedance unit cells 218 and the low-impedance unit cells 220 are at least arranged in a continuous alternating manner, and the alternating arrangement direction of the high-impedance unit cells 218 and the low-impedance unit cells 220 is perpendicular to the direction from the high-impedance region to the low-impedance region;

[0079] In the direction from the high impedance region to the low impedance region, the acoustic impedance of the high impedance unit 218 shows a trend of gradually decreasing;

[0080] In the direction from the low-impedance region to the high-impedance region, the acoustic impedance of the low-impedance unit body 220 decreases gradually.

[0081] In order to fully transmit the ultrasonic signal that is not reflected by the high-impedance area, the fully transparent area may include a plurality of high-impedance unit bodies 218 and low-impedance unit bodies 220. When the fully transparent area is formed, the high-impedance unit bodies 218 and the low-impedance unit bodies 220 are mutually embedded and in close contact. In addition, the high-impedance unit bodies 218 and the low-impedance unit bodies 220 should also be respectively contacted and connected with the high-impedance area and the low-impedance area, so that the high-impedance unit bodies 218 and the low-impedance unit bodies 220 can fill the space between the high-impedance area and the low-impedance area, thereby avoiding the existence of gaps that affect the propagation of ultrasonic signals.

[0082] Figure 3 FIG2 shows a cross-sectional view of an embodiment of the acoustic amplification stack 214, and also shows a cross-sectional schematic diagram of the full-transmission region. As can be seen from the figure, in the cross-section of the full-transmission region, the high-impedance unit body 218 and the low-impedance unit body 220 will form a continuous alternating arrangement state, and the alternating arrangement direction is perpendicular to the direction from the high-impedance region to the low-impedance region. Specifically, Figure 3 In the cross-sectional embodiment of the full transmission area shown in FIG, Figure 5 The cross section along the length direction of the array element unit 202 can also be Figure 5 The cross section along the width direction of the array element unit 202 is: Figure 5 The length direction of the array element unit 202 is Figure 5 The up and down directions in .

[0083] Further, by Figure 3As can be seen, along the direction from the high-impedance region toward the low-impedance region, the high-impedance unit body 218 and the low-impedance unit body 220 are in contact with and connected to the high-impedance region and the low-impedance region respectively. It should be noted that the acoustic impedance of the high-impedance unit body 218 is relatively high, while the acoustic impedance of the low-impedance unit body 220 is relatively low. For example, the acoustic impedance of the high-impedance unit body 218 can be much greater than that of the low-impedance unit body 220. As a result, a continuous arrangement of high acoustic impedance and low acoustic impedance is formed along the direction perpendicular to the high-impedance region and toward the low-impedance region. The length of the continuous arrangement is consistent with the projection length of the high-impedance region and the low-impedance region onto the backing sound-absorbing unit 216.

[0084] During specific implementation, the acoustic impedance of the high-impedance unit body 218 and the acoustic impedance of the low-impedance unit body 220 are both in a gradual state. For example, in the direction from the high-impedance area to the low-impedance area, the acoustic impedance of the high-impedance unit body 218 tends to gradually decrease, and in the direction from the low-impedance area to the high-impedance area, the acoustic impedance of the low-impedance unit body 220 also tends to gradually decrease. Therefore, a continuous change in acoustic impedance can be formed in the thickness direction of the acoustic amplification stack 214, thereby effectively transmitting the ultrasonic signal that is not reflected by the high-impedance area to the low-impedance area.

[0085] Specifically, when the acoustic impedance changes continuously, the change in acoustic impedance can be exponential or linear. At this time, the high-impedance unit body 218 and the low-impedance unit body 220 can be regarded as including multiple continuously changing thin layers, wherein the slight impedance difference of each thin layer only produces weak reflection. These reflected ultrasonic waves form a phase shift due to the path difference during propagation. The fully transparent layer of the present invention can cause the reflected ultrasonic waves to destructively interfere when superimposed, and the total reflection approaches zero. Therefore, it can be seen that the transmission coefficient of the fully transparent area is close to 1, and a fully transparent state can be formed.

[0086] It should be noted that the corresponding acoustic impedances of the high impedance region and the low impedance region should remain stable, that is, the corresponding acoustic impedance gradient state of the high impedance unit body 218 and the low impedance unit body 220 should not be adopted, such as Figure 3 In the middle, the high impedance area and the low impedance area are in the shape of a flat plate. From the above description, it can be seen that there is no corresponding acoustic impedance gradient state.

[0087] In one embodiment of the present invention, the high-impedance unit body 218 and the low-impedance unit body 220 have the same cross-sectional shape, wherein:

[0088] At least one inclined non-parallel surface structure 222 is provided on the corresponding cross sections of the high-impedance unit body 218 and the low-impedance unit body 220, wherein the inclined non-parallel surface structure 222 is non-parallel to the high-impedance region and the low-impedance region;

[0089] For any inclined non-parallel surface structure 222, the angle α between the inclined non-parallel surface structure 222 and the unit cross-section bottom surface 224 of the corresponding cross-section of the high-impedance unit 218 or the low-impedance unit 220 is 15° to 60°.

[0090] In the fully transparent region, the high-impedance unit body 218 and the low-impedance unit body 220 form a mutually plug-in connection state, wherein, when the high-impedance unit body 218 and the low-impedance unit body 220 are plug-in connected, the outer surface of the inclined non-parallel surface structure 222 formed by the high-impedance unit body 220 is in close contact with the outer surface of the corresponding inclined non-parallel surface structure 222 formed by the corresponding low-impedance unit body 220.

[0091] In order to enable the high-impedance unit body 218 and the low-impedance unit body 220 to be embedded in each other and tightly connected, the high-impedance unit body 218 and the low-impedance unit body 220 may be configured to have the same cross-sectional shape, such as Figure 3 , an embodiment is shown in which the corresponding cross-sections between the high-impedance unit body 218 and the low-impedance unit body 220 are three triangles. In addition, the corresponding cross-sectional shapes of the high-impedance unit body 218 and the low-impedance unit body 220 can also be trapezoidal, arc-shaped or wedge-shaped. The specific corresponding cross-sectional shapes can be selected as needed, but on the corresponding cross-sections of the high-impedance unit body 218 and the low-impedance unit body 220, there is at least one inclined non-parallel surface structure 222. The cross-sections are not listed here one by one, so long as they can form at least one inclined non-parallel surface structure 222 and meet the above-mentioned connection state of the high-impedance region unit body 218 and the low-impedance unit body 220 being embedded in each other and in close contact.

[0092] It can be understood that when the cross-sections of the high-impedance unit body 218 and the low-impedance unit body 220 are triangular, the three-dimensional structures corresponding to the high-impedance unit body 218 and the low-impedance unit body 220 can be cones or triangular pyramids. The three-dimensional structure is based on whether the cross-sections are triangular. It can be seen that the high-impedance unit body 218 and the low-impedance unit body 220 can be in the shape of cones, triangular pyramids, etc., and the high-impedance unit body 218 and the low-impedance unit body 220 can be distributed in an array to meet the requirements. Figure 3 The cross-sectional shape formed in the embodiment and the above description shall prevail.

[0093] Figure 4An embodiment in which the cross-sectional shape is a triangle is shown. In the cross-section, the sides of the triangle can form an inclined non-parallel surface structure 222, and the bottom surface 224 of the unit body cross-section can be a plane corresponding to the high-impedance area and the low-impedance area. For example, for the high-impedance unit body 218, the bottom surface 224 of the unit body cross-sectional shape should be the interface / plane formed by the high-impedance unit body 218 and the high-impedance area. For the low-impedance unit body 220, the bottom surface 224 of the unit body cross-sectional shape should be the interface / plane formed by the low-impedance unit body 220 and the low-impedance area.

[0094] It should be noted that when the cross-sectional shape is Figure 4 When the high-impedance unit 218 and the low-impedance unit 220 have a triangular shape, the acoustic impedance of the high-impedance unit 218 and the low-impedance unit 220 forms a continuous change in a quasi-exponential change. It is understood that by setting the corresponding cross-sectional shapes and corresponding three-dimensional shapes of the high-impedance unit 218 and the low-impedance unit 220, the corresponding acoustic impedance can be continuously changed exponentially or linearly, which will not be described in detail here. In addition, when in contact with the low-impedance area, the acoustic impedance corresponding to the contact interface between the high-impedance unit 218 and the low-impedance area should be as close as possible to the acoustic impedance of the low-impedance area to avoid the aforementioned problems caused by a large difference in acoustic impedance, thereby improving the efficiency and reliability of the fully transparent area in transmitting sound waves not reflected by the high-impedance area.

[0095] Depend on Figure 3 As can be seen from the above description, when the cross-sectional shape is triangular, for the high-impedance unit 218 , the top of the triangular cross-sectional shape contacts the low-impedance region, while for the low-impedance unit 220 , the top of the triangular cross-sectional shape contacts the high-impedance region. Figure 3 , the high-impedance unit body 218 and the low-impedance unit body 220 are connected to each other in an interlocking manner, so as to form a mutual embedding between the high-impedance unit body 218 and the low-impedance unit body 220. It can be understood that based on the corresponding shapes of the high-impedance unit body 218 and the low-impedance unit body 220, the high-impedance unit body 218 and the low-impedance unit body 220 can form the above-mentioned gradual change state of the corresponding acoustic impedance.

[0096] Figure 4In the embodiment shown in FIG, the angle α formed between the inclined non-parallel surface structure 222 and the bottom surface 224 of the unit cell cross section is 15° to 60°. Specifically, the size of the angle α formed should be based on whether the high-impedance unit cell 218 and the low-impedance unit cell 220 are in close contact with each other and whether a fully transparent region can be effectively formed. Since the high-impedance unit cell 218 and the low-impedance unit cell 220 have the same cross-sectional shape, in order to form a mutually embedded and close contact state, the high-impedance unit cell 218 and the low-impedance unit cell 220 preferably adopt the same three-dimensional shape. In this case, the outer surface of the inclined non-parallel surface structure 222 formed by the high-impedance unit cell 220 is in close contact with the outer surface of the corresponding inclined non-parallel surface structure 222 formed by the corresponding low-impedance unit cell 220.

[0097] Furthermore, to achieve a fully transparent region, the thickness of the fully transparent region is 0.125λ² to 0.25λ², where λ² is the equivalent wavelength of the equivalent sound velocity of ultrasound at the center frequency when passing through the fully transparent region. It can be understood that by setting the thickness of the fully transparent region to 0.125λ² to 0.25λ², and based on the continuous change in acoustic impedance formed by the high-impedance unit cells 218 and the low-impedance unit cells 220, the fully transparent region can achieve a fully transparent effect. Because the high-impedance unit cells 218 and the low-impedance unit cells 220 adopt the same three-dimensional shape, the height of the high-impedance unit cells 218 and the thickness of the low-impedance unit cells 220 are consistent with the thickness of the fully transparent region. In specific implementations, the thickness of the high-impedance region should generally be between 0.125λ² and 0.25λ².

[0098] In one embodiment of the present invention, the high-impedance unit body 218 is prepared on the high-impedance region, wherein the high-impedance unit body 218 and the high-impedance region are prepared by an integrated molding process;

[0099] The low-impedance unit body 220 is prepared on the low-impedance region, wherein the low-impedance unit body 220 and the low-impedance region are prepared by an integrated molding process;

[0100] When preparing the acoustic amplification stack 214, a high-impedance region and a high-impedance unit body 218 distributed on the high-impedance region are first prepared. Thereafter, a low-impedance unit body 220 and a corresponding low-impedance region are prepared on the high-impedance region, wherein the prepared low-impedance unit body 220 is embedded in and in close contact with the high-impedance unit body 218.

[0101] In a specific implementation, the high-impedance unit body 218 and the high-impedance region can be formed using an integrated molding process, that is, the high-impedance unit body 218 and the high-impedance region can be formed simultaneously. Similarly, the low-impedance unit body 220 and the low-impedance region can be formed using an integrated molding process, that is, the low-impedance unit body 220 and the low-impedance region can be formed simultaneously.

[0102] When preparing the acoustic amplification stack 214, a high-impedance region and high-impedance unit cells 218 are generally prepared first. Subsequently, low-impedance unit cells 220 and a low-impedance region are formed on the high-impedance region to effectively form the high-impedance region-fully-transmissive region-low-impedance region structure of the present invention. The following describes an example process for preparing the acoustic amplification stack 214.

[0103] In one embodiment of the present invention, when preparing the acoustic amplification stack 214, the preparation method includes:

[0104] Providing a high-impedance substrate and patterning the high-impedance substrate to generate a high-impedance region and form a plurality of high-impedance unit bodies 218 on the high-impedance region after patterning;

[0105] Applying bonding connections to at least the high-resistance unit body,

[0106] A low-impedance unit 218 and a low-impedance region are formed on the high-impedance region.

[0107] At least the corresponding surfaces of the low-resistance unit body 228 and the high-resistance unit body 218 are locally heated to form a bonding layer after the local heating, and the formed bonding layer is used to at least ensure close contact between the low-barrier unit body 220 and the high-resistance unit body 218.

[0108] Specifically, the high-impedance substrate is made of a high-impedance material, including a metal or a rigid dielectric material. When the high-impedance substrate is made of metal, the patterning method for the high-impedance substrate includes at least ablation. It should be noted that when the high-impedance substrate is made of a metal material, the metal material can be a pure metal or an alloy metal, such as a tungsten alloy or cemented carbide, whichever material can provide high acoustic impedance.

[0109] In specific implementation, when a metal is selected as the high-impedance substrate and patterning is performed by ablation, the ablation method can be: using an ultrashort pulse laser (femtosecond / picosecond level) to ablate the high-impedance substrate layer by layer, combining a dynamic focusing method to directly form a high-impedance unit body 218 on the surface of the high-impedance substrate, and the rest of the high-impedance substrate can form a high-impedance region, thereby achieving the simultaneous preparation of the high-impedance unit body 218 and the high-impedance region.

[0110] It should be noted that the thickness precision of the high-impedance unit body 218 and the high-impedance region should be controlled at the nanometer level. The process conditions, process, and dynamic focusing method of ultrashort pulse laser ablation can be selected as needed, specifically based on the ability to produce the corresponding high-impedance unit body 218. The preparation of the high-impedance unit body 218 can be referred to the corresponding description above. When a rigid dielectric material is used as the high-impedance substrate, the specific method of patterning the high-impedance substrate can be referred to the description herein, based on the ability to adapt to the characteristics of the selected rigid dielectric material and produce the desired high-impedance unit body 218. No further examples will be given here.

[0111] Since the high-impedance unit body 218 and the low-impedance unit body 220 are made of different materials, in order to ensure the stability and reliability of the connection contact between the high-impedance unit body 218 and the low-impedance unit body 220, before preparing the low-impedance unit body 220, a bonding connector can be coated on at least the high-impedance unit body 218. Thereafter, the low-impedance unit body 220 and the low-impedance region can be prepared on the high-impedance region. The low-impedance region and the low-impedance unit body 220 can be made of conventional low-impedance materials, such as low-impedance materials including silicone and / or PDMS (polydimethylsiloxane). When preparing the low-impedance region and the low-impedance unit body 220, the low-impedance material can be sprayed on the high-impedance unit body 218 and the high-impedance region by a spraying process, and then cured by a curing method commonly used in the art to form the low-impedance region and the low-impedance unit body 220 after the curing process. Specifically, the specific spraying method, process conditions, and curing method can all adopt conventional methods.

[0112] It should be noted that the bonding material can be a commonly used silane coupling agent, and of course, the bonding material can also be in other forms. When the bonding material is a silane coupling agent, it can be coated on the high-impedance unit 218 using existing technical means. Of course, the silane coupling agent can also be coated on the high-impedance area at the same time. After the low-impedance material is sprayed and before the low-impedance material is completely cured, in order to form a bonding layer, the area coated with the silane coupling agent can be locally heated. For example, at least the corresponding surfaces of the low-impedance unit 220 and the high-impedance unit 218 can be locally heated. The local heating temperature can be 80°C to 120°C. The local heating temperature and local heating method can be selected as needed, so as to form a bonding layer using the silane coupling agent.

[0113] In a specific implementation, when a silane coupling agent is used to form a bonding connection layer, the low-barrier unit 220 can be in close contact with the high-impedance unit 218 , thereby further ensuring the stability and reliability of the connection contact between the high-impedance unit 218 and the low-impedance unit 220 .

[0114] In addition, when the high-impedance substrate is patterned, etching can be set on the high-impedance unit body 218 to form a nano-scale dovetail groove array. When the low-impedance material is sprayed, the low-impedance material can be sprayed on the nano-scale dovetail groove array at the same time, thereby forming an interlocking structure between the high-impedance unit body 218 and the low-impedance unit body 220, further ensuring the stability and reliability of the connection contact between the high-impedance unit body 218 and the low-impedance unit body 220.

[0115] In one embodiment of the present invention, for any array element unit 202, when the array element unit 202 is working, the piezoelectric unit 210 is in a piezoelectric resonance mode based on the high impedance region within the array element unit 202, wherein:

[0116] When the piezoelectric unit 210 is in the piezoelectric resonance mode, a resonant oscillation is formed in a free-fixed boundary state. The thickness of the piezoelectric unit 210 is 0.25λ3~0.5λ3, λ3 is the wavelength of the ultrasonic wave passing through the piezoelectric unit 210 at the center frequency, and the center frequency is generally the resonant frequency of the piezoelectric unit 210.

[0117] It should be understood that due to the presence of the acoustic amplification stack 214, the resonant mode of the piezoelectric unit 210 differs from the half-wavelength resonant mode of a conventional array transducer. In one embodiment of the present invention, due to the relatively large equivalent acoustic impedance of the acoustic amplification stack 214 and the high mass of the high-impedance region near the piezoelectric unit 210, the resonance of the piezoelectric unit 210 is similar to the vibration mode of a rod with one side fixed and the other free. In other words, the piezoelectric unit 210 forms a resonant oscillation in a free-fixed boundary state. The free vibrating side of the piezoelectric unit 210 can emit ultrasonic energy, reducing the pulse width and increasing the frequency domain bandwidth of the array ultrasonic transducer of the present invention. Specifically, the thickness of the piezoelectric unit 210 can be 0.25λ3 to 0.5λ3, where λ3 is the wavelength of the ultrasonic wave passing through the piezoelectric unit 210 at the center frequency. In other words, when the thickness of the piezoelectric unit 210 is at least 0.25λ3, the piezoelectric unit 210 can generate resonant vibration, and the frequency of the resonant vibration is the center frequency. Specifically, the free vibration side of the piezoelectric unit 210 is the side of the piezoelectric unit 210 away from the high impedance area, and the fundamental frequency is the center frequency of the ultrasonic transducer. The fundamental frequency / center frequency of the ultrasonic transducer is consistent with the existing technology and will not be repeated here.

[0118] It should be noted that the high-impedance area close to the piezoelectric unit 210 has a large mass. Specifically, the average weight and average density of the high-impedance area are respectively greater than the average weight and average density of other structures. As mentioned above, when the high-impedance area is made of metal, the high-impedance area can have a larger average weight and average density.

[0119] In one embodiment of the present invention, the array element main component further includes a matching unit located on the piezoelectric unit 210, wherein:

[0120] The matching unit includes a matching first unit layer 206 located on the piezoelectric unit 210 and a matching second unit layer 204 located on the matching first unit layer 206;

[0121] The acoustic impedance of the first unit layer 206 is matched to be greater than the acoustic impedance of the second unit layer 206 .

[0122] Figure 1 In the embodiment, a matching layer 106 is provided on the piezoelectric layer 110, so as to utilize the matching layer 106 to propagate the forward ultrasonic signal into the medium to be measured as much as possible. Therefore, in order to form a form corresponding to the matching layer 106, the array element main component of the present invention should also include a matching unit, wherein the matching unit should be provided on the piezoelectric unit 210, such as Figure 2 As shown, the function of the matching unit should be consistent with that of the matching layer 106 .

[0123] To further improve the transmittance of forward ultrasonic signals, in one embodiment of the present invention, the matching unit may include a first matching unit layer 206 and a second matching unit layer 204, wherein the first matching unit layer 206 is located on the piezoelectric unit 210, and the second matching unit layer 204 is located on the first matching unit layer 206. It should be noted that the thickness of the first matching unit layer 206 and the second matching unit layer 204 is approximately 0.25λ4 to ensure maximum acoustic energy transmission, where λ4 is the wavelength of the ultrasonic wave at the center frequency when it passes through the first matching unit layer 206 and the second matching unit layer 204.

[0124] Furthermore, the acoustic impedance of the first unit layer 206 can be matched to 6-10 MRayls, and the acoustic impedance of the second unit layer 204 can be matched to 2-4 MRayls. In other words, in general, the thickness of the first unit layer 206 is different from the thickness of the second unit layer 204. By setting the corresponding acoustic impedances of the first unit layer 206 and the second unit layer 204, the transmittance of the forward ultrasonic signal can be effectively improved, ensuring maximum acoustic energy transmission. The first unit layer 206 and the second unit layer 204 are typically prepared by mixing and curing epoxy resin and inorganic metal powder.

[0125] In specific implementation, the main component isolation member 208 is usually filled with pure silicone, whose acoustic impedance is 1-2 MRayls, which plays the role of fixing and protecting the array element unit 202 without affecting the electroacoustic performance of the array element unit 202.

[0126] Figure 5 Shown in Figure 2 A top view of the array ultrasound transducer unit 200, Figure 6 Shown in Figure 2The side view of the array ultrasonic transducer unit 200 is shown in FIG5 , and it can be electrically connected to one or more array element units 202 through the first connecting circuit board 302 and the second connecting circuit board 304. Figure 5 3 shows a form in which the first connecting circuit board 302 and the second connecting circuit board 304 are connected and matched with three array element units 202 at the same time. Specifically, the first connecting circuit board 302 and the second connecting circuit board 304 can be flexible circuit boards.

[0127] Figure 5 In the embodiment, the piezoelectric unit 210 within each array element 202 can be connected to the first connection circuit board 302 via the array element connection line 402. The second connection circuit board 304 is connected to the high-impedance region within the acoustic amplification stack 214 to form a common ground line. The first connection circuit board 302 and the second connection circuit board 304 can adopt conventional conventional forms, so long as they can connect and lead out the array element 202.

[0128] The first connection circuit board 302 and the second connection circuit board 304 can be made of conductive epoxy resin compound or silver paste. The conductive epoxy resin compound refers to a mixture formed by adding conductive fillers to epoxy resin. In order to improve the reliability of the connection, a protective layer 502 can be provided on the backing sound absorbing unit 216. Figure 6 As shown, the protective layer 502 is placed between the backing sound absorbing unit 216 and the piezoelectric unit 210, covering the side of the acoustic amplification stack 214, so as to prevent the problem of conductive epoxy resin compound or silver paste causing conduction between the upper and lower surfaces of the piezoelectric unit 210. The protective layer 502 can be made of low-impedance epoxy resin or silicone.

[0129] Figure 7 FIG1 is a FEM simulation data diagram of the pulse echo performance of the array ultrasonic transducer unit 200 of the present invention and the array ultrasonic transducer in the prior art. The array ultrasonic transducer in the prior art can be Figure 1 The array ultrasonic transducer device 100 may, of course, be in other forms. Figure 8 Shown in Figure 7 Schematic diagram of calculation results of FEM simulation data, Figure 8 The traditional transducer is the arrayed ultrasonic transducer in the prior art, wherein the traditional transducer adopts a traditional backing sound absorption structure, and the optimized transducer is the arrayed ultrasonic transducer unit 200 of the present invention.

[0130] Figure 7In the figure, the diagram where 702 is located is a diagram of the pulse echo time domain signal of the arrayed ultrasonic transducer unit 200 of the present invention, and the diagram where 701 is located is a diagram of the pulse echo time domain signal of the arrayed ultrasonic transducer in the prior art. It can be seen from the diagram that the echo sensitivity of the arrayed ultrasonic transducer unit 200 of the present invention is much greater than that of the arrayed ultrasonic transducer in the prior art, reaching 6.74 dB, that is, under the same voltage signal excitation, the echo amplitude of the arrayed ultrasonic transducer unit 200 of the present invention is more than twice the echo amplitude of the arrayed ultrasonic transducer in the prior art.

[0131] Figure 7 In the diagram where 703 is located, when the dotted line intersects the solid curve, the corresponding frequency f1 and frequency f2 can be obtained. Similarly, in the diagram where 704 is located, when the dotted line intersects the solid curve, the corresponding frequency f1 and frequency f2 can be obtained. Based on the obtained frequency f1 and frequency f2, the center frequency f can be calculated. c , generally, f c =(f1+f2) / 2.

[0132] Depend on Figure 7 From the FEM simulation of the pulse echo performance in the above, it can be seen that the frequencies f1 and f2 obtained above are specifically the frequencies corresponding to the time when the frequency domain echo response is reduced by half, that is, -6dB. At this time, f c To define the -6dB center frequency of the transducer, BW is the -6dB relative frequency domain bandwidth, V is the voltage amplitude of the echo, and RS is the relative sensitivity calculated from the echo voltage V.

[0133] For the frequency domain bandwidth BW, we have:

[0134] Figure 7 , the diagram at 704 is the echo frequency domain response of the arrayed ultrasonic transducer unit 200 of the present invention, and the diagram at 703 is the echo frequency domain response of the arrayed ultrasonic transducer in the prior art. As can be seen from the diagram, the -6dB bandwidth of the arrayed ultrasonic transducer unit 200 of the present invention reaches 87.80%, which is 10.34% higher than the bandwidth of the arrayed ultrasonic transducer in the prior art.

[0135] It can be seen from the above simulation that the arrayed ultrasonic transducer unit 200 of the present invention can simultaneously improve the sensitivity and bandwidth acoustic performance, that is, the arrayed ultrasonic transducer unit 200 can have high frequency domain bandwidth and sensitivity.

Claims

1. An array ultrasonic transducer with high-frequency bandwidth and sensitivity, characterized by: The arrayed ultrasonic transducer includes a backing sound absorbing unit and an array element array arranged on the backing sound absorbing unit, wherein: The array element array includes at least one array element unit; Any array element unit at least includes an array element main component for ultrasonic transduction and an acoustic amplification stack adapted to the array element main component, wherein: The array element main component includes a piezoelectric unit adjacent to a backing sound absorbing unit; The acoustic amplification stack is located between the piezoelectric unit and the backing sound absorption unit, wherein, along the direction from the piezoelectric unit to the backing sound absorption unit, the acoustic amplification stack includes at least a high impedance region, a fully transparent region, and a low impedance region arranged in sequence. The ultrasonic signal generated by the piezoelectric unit and propagating toward the backing sound absorbing unit is reflected by the high impedance area, and the ultrasonic signal not reflected by the high impedance area is fully transmitted to the low impedance area through the fully transparent area, so that the fully transmitted ultrasonic signal is fully absorbed by the low impedance area and / or the backing sound absorbing unit.

2. The array ultrasonic transducer with high-frequency bandwidth and sensitivity according to claim 1, characterized in that: The full transmission area includes a plurality of high-impedance unit bodies and low-impedance unit bodies corresponding to the high-impedance unit bodies, wherein: The high-impedance unit body and the low-impedance unit body are embedded in each other and in close contact. On the cross section of the fully transparent region, the high-impedance unit cells and the low-impedance unit cells are at least arranged in a continuous alternating pattern, and the alternating arrangement direction of the high-impedance unit cells and the low-impedance unit cells is perpendicular to the direction from the high-impedance region to the low-impedance region; From the high impedance area to the low impedance area, the acoustic impedance of the high impedance unit body gradually decreases; From the low impedance area to the high impedance area, the acoustic impedance of the low impedance unit body tends to gradually decrease.

3. The array ultrasonic transducer with high-frequency bandwidth and sensitivity according to claim 2, characterized in that: The high impedance unit cell and the low impedance unit cell have the same cross-sectional shape, wherein: At least one inclined non-parallel surface structure is provided on the corresponding cross sections of the high-impedance unit body and the low-impedance unit body, wherein the inclined non-parallel surface structure is non-parallel to the high-impedance region and the low-impedance region; For any inclined non-parallel surface structure, the angle α between the inclined non-parallel surface structure and the bottom surface of the unit cross section of the corresponding cross section of the high-impedance unit body or the low-impedance unit body is 15° to 60°; In the fully transparent region, the high-impedance unit body and the low-impedance unit body form a mutually plug-in connection state, wherein, when the high-impedance unit body and the low-impedance unit body are plug-in connected, the outer surface of the inclined non-parallel surface structure formed by the high-impedance unit body is in close contact with the outer surface of the corresponding inclined non-parallel surface structure formed by the corresponding low-impedance unit body.

4. The array ultrasonic transducer with high-frequency bandwidth and sensitivity according to claim 2, characterized in that: The thickness of the fully transparent area is λ2 / 8 to λ2 / 4, wherein λ2 is the equivalent wavelength of the equivalent sound velocity of the ultrasonic wave passing through the fully transparent area at the center frequency. The cross-sectional shapes of the high-impedance unit body and the low-impedance unit body include triangle, trapezoid, arc or wedge shape.

5. The array ultrasonic transducer with high-frequency bandwidth and sensitivity according to claim 2, characterized in that: The high impedance region in the acoustic amplification stack contacts the piezoelectric unit, and the low impedance region in the acoustic amplification stack contacts the backing sound absorption unit, wherein: The acoustic impedance of the high impedance region is at least twice the acoustic impedance of the piezoelectric unit; The acoustic impedance of the low-impedance unit is at most 1 / 10 of the acoustic impedance of the piezoelectric unit.

6. The array ultrasonic transducer with high-frequency bandwidth and sensitivity according to any one of claims 2 to 5, characterized in that: The high-impedance unit body is prepared on the high-impedance area, and the high-impedance unit body and the high-impedance area are prepared and formed by an integrated molding process; The low-impedance unit body is prepared on the low-impedance area, and the low-impedance unit body and the low-impedance area are prepared and formed by an integrated molding process; When preparing the acoustic amplification stack, a high-impedance region and high-impedance unit bodies distributed on the high-impedance region are first prepared. Thereafter, a low-impedance unit body and a corresponding low-impedance region are prepared on the high-impedance region, wherein the prepared low-impedance unit body is embedded in and in close contact with the high-impedance unit body.

7. The array ultrasonic transducer with high-frequency bandwidth and sensitivity according to claim 6, characterized in that: When preparing the acoustic amplification stack, the preparation method includes: Providing a high-impedance substrate and patterning the high-impedance substrate to generate a high-impedance region and form a plurality of high-impedance unit bodies on the high-impedance region after patterning; Applying bonding connections to at least the high-resistance unit body, A low-impedance unit body and a low-impedance region are formed on the high-impedance region. At least the corresponding surfaces of the low-resistance unit body and the high-resistance unit body are locally heated to form a bonding connection layer after the local heating, and the formed bonding connection layer is used to at least make the low-resistance unit body and the high-resistance unit body closely contact each other.

8. The array ultrasonic transducer with high-frequency bandwidth and sensitivity according to claim 7, characterized in that: The high-impedance substrate is made of a high-impedance material, and the high-impedance material used by the high-impedance substrate includes metal or rigid dielectric material, wherein: When the high-resistance substrate is made of metal, the patterning method for the high-resistance substrate at least includes ablation.

9. The array ultrasonic transducer with high-frequency bandwidth and sensitivity according to any one of claims 1 to 5, characterized in that: For any array element unit, when the array element unit is working, the piezoelectric unit is in a piezoelectric resonance mode based on the high impedance region within the array element unit, wherein: When the piezoelectric unit is in the piezoelectric resonance mode, a resonant oscillation in a free-fixed boundary state is formed. The thickness of the piezoelectric unit is 0.25λ3 to 0.5λ3, where λ3 is the wavelength of the ultrasonic wave passing through the piezoelectric unit at the center frequency.

10. The array ultrasonic transducer with high-frequency bandwidth and sensitivity according to any one of claims 1 to 5, characterized in that: The array element main component further includes a matching unit located on the piezoelectric unit, wherein: The matching unit includes a matching first unit layer located on the piezoelectric unit and a matching second unit layer located on the matching first unit layer; The acoustic impedance of the first unit layer is matched to be greater than the acoustic impedance of the second unit layer.

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