Piezoelectric micromechanical ultrasonic transducer array

Abstract

The application relates to the technical field of electro-acoustic transducers, and discloses a piezoelectric micro-mechanical ultrasonic transducer array, which comprises a first array structure, the first array structure comprises a plurality of array-arranged first array elements, each first array element is a first piezoelectric micro-mechanical ultrasonic transducer, the row spacing and the column spacing of the first array elements in the first array structure are equal, the number, the row spacing and the column spacing of the first array elements in the first array structure meet a first preset condition, and the first preset condition comprises that the difference between the first direction angle of the first array structure and a preset first target direction angle is less than a first preset error value.

Description

Technical Field

[0001] This invention relates to the field of electroacoustic transducer technology, and more particularly to a piezoelectric micromechanical ultrasonic transducer array. Background Technology

[0002] Ultrasonic transducers have wide applications in non-destructive testing, industrial automation, target recognition, medical imaging, and velocity and distance detection. However, traditional ultrasonic transducers based on bulk piezoelectric ceramic materials suffer from drawbacks such as poor acoustic coupling performance (in water or air) and high costs associated with fabricating two-dimensional arrays for 3D imaging. Therefore, micromechanical ultrasonic transducers (MUTs) based on the increasingly mature Microelectromechanical Systems (MEMS) technology have emerged. Compared to traditional ultrasonic transducers, MUTs offer superior acoustic coupling performance, lower cost, and advantages such as smaller size, lower power consumption, higher bandwidth, ease of fabrication into compact, high-capacity arrays, and easier integration with electronic systems.

[0003] Based on their driving methods, micromechanical ultrasonic transducers can be divided into capacitive micromechanical ultrasonic transducers (CMUTs) and piezoelectric micromechanical ultrasonic transducers (PMUTs). Compared to the earlier developed and more mature capacitive micromechanical ultrasonic transducers, piezoelectric micromechanical ultrasonic transducers do not have the disadvantage of requiring a higher driving voltage to achieve target sensitivity. Furthermore, piezoelectric ultrasonic transducers have a larger capacitance value, making them more compatible with operating circuits and less sensitive to parasitic capacitance.

[0004] Currently, piezoelectric micromechanical ultrasonic transducers have been applied in many fields such as imaging and sensing, playing an important role in ultrasonic applications due to their small size, low cost, and excellent performance. However, when the size of piezoelectric ultrasonic transducers is reduced to the wavelength of the applied sound waves, the radiated sound field of a single transducer exhibits isotropic characteristics, meaning that sound waves of similar intensity are generated in all directions. This characteristic is particularly pronounced in the application frequency range below 1MHz, making existing piezoelectric micromechanical ultrasonic transducers unable to meet the high directivity requirements of some low-frequency ultrasonic applications. Traditional thickness-mode-based ultrasonic transducers achieve arraying and high directivity through cutting, but they have drawbacks such as single frequency and small fill factor (the ratio of effective transducer area to total area). Summary of the Invention

[0005] This invention provides a piezoelectric micromechanical ultrasonic transducer array. By reasonably setting the number of array elements and the spacing between adjacent array elements in the piezoelectric micromechanical ultrasonic transducer array, the transducer array can meet the requirement of high directivity when the radius of the piezoelectric ultrasonic transducer is reduced to the order of sound wave wavelength.

[0006] A piezoelectric micromechanical ultrasonic transducer array, comprising:

[0007] A first array structure, comprising a plurality of array elements arranged in an array, each of the first array elements being a first piezoelectric micromechanical ultrasonic transducer;

[0008] In the first array structure, the row spacing and column spacing of the first array elements are equal; the number of the first array elements, the row spacing and the column spacing in the first array structure meet the first preset condition, the first preset condition including that the difference between the first orientation angle of the first array structure and the preset first target orientation angle is less than the first preset error value.

[0009] In the above scheme, the first piezoelectric micromechanical ultrasonic transducer includes a support layer, a bottom electrode layer disposed on the support layer, a pressure point layer disposed on the bottom electrode layer, and a top electrode disposed on the pressure point layer. The support layer has a cavity on the side opposite to the top electrode.

[0010] In the above scheme, the number of the first array elements, row spacing, and column spacing in the first array structure are determined based on the cavity size, number of sound waves, and first target direction angle of the first piezoelectric micromechanical ultrasonic transducer.

[0011] In the above scheme, the first array element is a circular piezoelectric micromechanical ultrasonic transducer, and the cross-section of the cavity of the first piezoelectric micromechanical ultrasonic transducer is circular;

[0012] The number of first array elements, row spacing, and column spacing in the first array structure are determined based on the cavity size, number of sound waves, and first target orientation angle of the first piezoelectric micromechanical ultrasonic transducer, including:

[0013] The number of first array elements, row spacing, and column spacing in the first array structure are determined according to the orientation angle function, wherein the expression of the function is:

[0014]

[0015] In the formula, N is the number of the first array elements in the first array structure;

[0016] k is the number of sound waves;

[0017] a is the radius of the cavity cross section;

[0018] p is the row spacing and column spacing of the first array element in the first array structure;

[0019] J3 is the third-order form of a Bessel function of the first kind.

[0020] In the above scheme, the first array elements of the first array structure form multiple array element rings, and the first array elements in each array element ring are interconnected to form a rectangle; the ratio of the top electrode to the cavity of all the first array elements in each array element ring is the same, and the ratios corresponding to all the array element rings of the first array structure satisfy a third preset condition, the third preset condition including the beamwidth of the first array structure being a preset beamwidth and / or the sidelobe level of the first array structure being a preset sidelobe level.

[0021] The above scheme also includes a second array structure, which includes multiple array elements arranged in an array. Each second array element is a second piezoelectric micromechanical ultrasonic transducer. The resonant frequency of the second array structure is different from that of the first array structure.

[0022] The second array element is located in the gap between the first array elements in the first array structure. The row spacing and column spacing of the first array elements in the first array structure are equal. The number of the first array elements, the row spacing, and the column spacing in the first array structure meet the second preset condition. The second preset condition includes that the difference between the second orientation angle of the second array structure and the preset second target orientation angle is less than the second preset error value.

[0023] In the above scheme, the gap of the first array element of the first array structure is a gap formed by four adjacent first array elements. Among the four adjacent first array elements, every two adjacent first array elements are adjacent in the row direction of the first array elements or adjacent in the column direction of the first array elements. The second array element is arranged at the center of the gap.

[0024] In the above scheme, a second array element is arranged in each gap of the first array structure.

[0025] In the above scheme, the first array structure is a square array containing N1 rows of first array elements and N1 columns of first array elements, and the second array is a square array containing N2 rows of second array elements and N2 columns of second array elements, where N1 and N2 are both positive integers.

[0026] In the above scheme, both the first array element and the second array element are circular piezoelectric micromechanical ultrasonic transducers, and the diameters of the first array element and the second array element are different.

[0027] In the above-described scheme implemented by the piezoelectric micromechanical ultrasonic transducer array, a first array structure can be used. This first array structure includes multiple array elements arranged in a single array, each element being a first piezoelectric micromechanical ultrasonic transducer. The row spacing and column spacing of the first array elements in the first array structure are equal. The number of first array elements, the row spacing, and the column spacing in the first array structure satisfy a first preset condition. This first preset condition includes that the difference between the first orientation angle of the first array structure and a preset first target orientation angle is less than a first preset error value. In this invention, by designing a square array of piezoelectric micromechanical ultrasonic transducers (PMUTs), and by setting a reasonable number of PMUTs and the spacing between adjacent PMUTs in the array, high array directivity and a small sidelobe level are achieved, sufficient to meet the general application requirements of ultrasonic velocimetry. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 A schematic diagram of the structure of a single PMUT in one embodiment of the present invention;

[0030] Figure 2 A schematic diagram of the structure of a PMUT uniform square matrix in one embodiment of the present invention;

[0031] Figure 3 An orientation angle of a designed PMUT uniform square matrix in one embodiment of the present invention;

[0032] Figure 4 A schematic diagram of the structure of a dual-frequency PMUT uniform array in one embodiment of the present invention;

[0033] Figure 5 An orientation angle of a designed dual-frequency PMUT uniform array in one embodiment of the present invention;

[0034] Figure 6 The relationship between the normalized vibration amplitude of a circular PMUT and the ratio of top electrode to cavity radius in one embodiment of the present invention;

[0035] Figure 7 One embodiment of the present invention is a ring-shaped amplitude-weighted PMUT uniform matrix;

[0036] Figure 8An embodiment of the present invention provides the orientation angle of a ring-shaped amplitude-weighted PMUT uniform matrix;

[0037] Explanation of the attached drawing numbers:

[0038] 1. Support layer; 2. Bottom electrode; 3. Piezoelectric layer; 4. Top electrode; 11. Cavity; 21. First element; 22. Second element. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Please see Figures 1 to 8 As shown, the piezoelectric micromechanical ultrasonic transducer array provided in this embodiment of the invention includes:

[0041] A first array structure, comprising a plurality of array elements arranged in an array, each of the first array elements being a first piezoelectric micromechanical ultrasonic transducer;

[0042] In the first array structure, the row spacing and column spacing of the first array elements are equal; the number of the first array elements, the row spacing and the column spacing in the first array structure meet the first preset condition, the first preset condition including that the difference between the first orientation angle of the first array structure and the preset first target orientation angle is less than the first preset error value.

[0043] The azimuth angle, also known as the half-power angle, is the angle at which the power of the ultrasonic main lobe attenuates to half of its central maximum value. It is the most important indicator for calibrating the directivity of a transducer. The influence of the number of array elements and the element spacing on the azimuth angle is analyzed.

[0044] Understandably, one of the advantages of piezoelectric micromechanical ultrasonic transducers is that reducing their size can lower manufacturing costs without compromising performance. However, when the radius of a piezoelectric ultrasonic transducer decreases to the order of the sound wave wavelength, the sound waves generated by a single piezoelectric ultrasonic transducer gradually exhibit isotropic characteristics, producing sound waves of almost the same intensity in all directions. This makes it difficult to achieve high directivity, which is insufficient to meet the high directivity requirements of certain low-frequency ultrasonic applications and hinders its ability to replace large-volume ultrasonic transducers in related fields.

[0045] In this embodiment, a highly directional PMUT array is achieved by designing the number and spacing of array elements, which has the advantages of concentrated energy, long propagation distance, and strong anti-interference ability. Figure 2This diagram illustrates how to obtain a desired orientation angle by adjusting the number of elements and the spacing between elements in a uniform PMUT array. The array is a cluster of multiple PMUTs. The shape of the PMUTs is not limited to a circle; they can also be rectangular, square, elliptical, etc.

[0046] In some embodiments, the structure of a piezoelectric micromechanical ultrasonic transducer typically consists of, from top to bottom, a top electrode layer, a piezoelectric layer, a bottom electrode layer, and a support layer, usually with a cavity at the bottom. Figure 1 As shown. The electrodes can be made of conductive materials such as Au, Pt, Mo, Al, and ITO (indium tin oxide), the piezoelectric layer can be made of piezoelectric materials such as PZT, AlN, ScAlN, ZnO, and KNN, and the support layer can be made of thin films such as Si, Glass, and PI. For a circular PMUT structure, its resonant frequency is: f_01∝t / a^2; the desired resonant frequency can be obtained by adjusting the film thickness and cavity area.

[0047] In some embodiments, the number of the first array elements, row spacing, and column spacing in the first array structure are determined based on the cavity size, number of sound waves, and first target orientation angle of the first piezoelectric micromechanical ultrasonic transducer.

[0048] Among them, the rectangular, square, and elliptical shape of the piezoelectric micromechanical ultrasonic transducer mainly refers to the shape of the cavity of the piezoelectric micromechanical ultrasonic transducer, that is, the horizontal cross section of the cavity is rectangular, square, or elliptical.

[0049] In some embodiments, the first array element is a circular piezoelectric micromechanical ultrasonic transducer, and the cross-section of the cavity of the first piezoelectric micromechanical ultrasonic transducer is circular;

[0050] The number of first array elements, row spacing, and column spacing in the first array structure are determined based on the cavity size, number of sound waves, and first target orientation angle of the first piezoelectric micromechanical ultrasonic transducer, including:

[0051] The number of first array elements, row spacing, and column spacing in the first array structure are determined according to the orientation angle function, wherein the expression of the function is:

[0052]

[0053] In the formula, N is the number of the first array elements in the first array structure;

[0054] k is the number of sound waves;

[0055] a is the radius of the cavity cross section;

[0056] p is the row spacing and column spacing of the first array element in the first array structure;

[0057] J3 is the third-order form of a Bessel function of the first kind.

[0058] It is understandable that the directional function of a circular matrix composed of individual PMUTs can be calculated using a normalized directional function. Here, J3 is the third-order form of a Bessel function of the first kind. Using this formula, it can be found that the directional function is approximately a function of the product of the number of row / column elements N and the spacing p between the row / column elements. Therefore, by designing the square array of PMUTs, the value of this product can be changed, thereby adjusting the directional function of the array.

[0059] Of course, when the shape of the piezoelectric micromechanical ultrasonic transducer is not circular, the normalized directional function is different, that is, piezoelectric micromechanical ultrasonic transducers of other shapes also have corresponding normalized directional functions.

[0060] In some application scenarios, such as Figure 2 As shown, the array elements are arranged in a square pattern, meaning the number of row elements is equal to the number of column elements, and they have the same element spacing in their respective directions. Using the directional function formula, the directional function can be calculated for different numbers of row / column elements and different row / column element spacings, thus determining the magnitude of the directional angle. For the desired high directivity of 12° directional angle, the directional angle of a PMUT uniform square array designed to achieve the expected effect is as follows: Figure 3 As shown.

[0061] In some embodiments, the first array elements of the first array structure form multiple array element rings, and the first array elements in each array element ring are interconnected to form a rectangle; the ratio of the top electrode to the cavity of all the first array elements in each array element ring is the same, and the ratios corresponding to all the array element rings of the first array structure satisfy a third preset condition, the third preset condition including the beamwidth of the first array structure being a preset beamwidth and / or the sidelobe level of the first array structure being a preset sidelobe level.

[0062] It is understandable that a ring-shaped amplitude weighting method is used to improve the directivity of the array. When the same driving voltage is applied, the vibration amplitude of the PMUT can be controlled by changing the area of ​​the top electrode. Figure 6 This paper demonstrates the relationship between the normalized vibration amplitude of a circular PMUT and the top electrode / cavity radius ratio. Adjusting the top electrode area effectively and conveniently changes the transducer's amplitude. Therefore, for a ring-shaped PMUT array, amplitude control can be achieved by adjusting the area of ​​the top electrode of the array elements in different ring regions, thereby optimizing the array's directional performance. Figure 7As shown, the array is divided into five rings, A, B, C, D, and E, from the inside out. When the vibration amplitudes of these rings are different, and a certain distribution pattern is adopted, the desired directional result can be obtained. The effect of ring amplitude weighting on the control of the array's azimuth angle is as follows: Figure 8 As shown. Furthermore, amplitude weighting of the PMUT array can also be achieved using phased array technology. Different forms of amplitude weighting can regulate the azimuth angle or sidelobe level to adapt to different application requirements.

[0063] In some application scenarios, such as Figure 6 As shown, by controlling the PMUT array through ring amplitude weighting, the PMUT array elements at different positions have different vibration amplitude values, which improves the azimuth angle or sidelobe level of the PMUT array. Simulation analysis shows that the ring amplitude weighting method effectively controls the azimuth angle of the PMUT array. Figure 7 As shown, the effects on beamwidth and sidelobe level are as follows: Figure 8 As shown, forward amplitude weighting (A:B:C:D:E = 1:2:3:4:5) can achieve a smaller beamwidth, while reverse amplitude weighting (A:B:C:D:E = 1:2:3:4:5) can achieve a smaller sidelobe level, providing extremely high flexibility.

[0064] In this embodiment, by changing the area of ​​the top electrode, the PMUT array is subjected to ring amplitude modulation, achieving effective adjustment of the beamwidth and sidelobe level of the radiated sound field, providing extremely high flexibility. Simultaneously, the method of amplitude modulation by changing the top electrode area is simple and reliable, reducing the design complexity of the peripheral circuitry. Table 1 below shows the beamwidth and sidelobe level of the ring amplitude-weighted PMUT uniform array.

[0065] Table 1

[0066] Amplitude weighted Beamwidth (-6dB) Side lobe level A:B:C:D:E = 1:2:3:4:5 10.8° -9.74dB A:B:C:D:E=1:1:1:1:1 11.52° -13.06dB A:B:C:D:E = 5:4:3:2:1 13.68° -20.71dB

[0067] In this embodiment, improving the directivity of the transducer also requires attention to the number and intensity of sidelobes (sidelobe level). The orientation angle of a designed PMUT uniform array is as follows: Figure 3 As shown, it achieves high directivity (e.g., 12° direction angle) and has a small sidelobe level, which is sufficient to meet the application requirements of general ultrasonic velocimetry.

[0068] In some embodiments, a second array structure is further included, the second array structure including a plurality of arrayed second array elements, each of the second array elements being a second piezoelectric micromechanical ultrasonic transducer, and the resonant frequency of the second array structure being different from the resonant frequency of the first array structure.

[0069] The second array element is located in the gap between the first array elements in the first array structure. The row spacing and column spacing of the first array elements in the first array structure are equal. The number of the first array elements, the row spacing, and the column spacing in the first array structure meet the second preset condition. The second preset condition includes that the difference between the second orientation angle of the second array structure and the preset second target orientation angle is less than the second preset error value.

[0070] Understandably, with a fixed number of array elements, increasing the element spacing is necessary to improve directivity. The greater the directivity and the smaller the azimuth angle, the larger the spacing and the larger the area occupied by the array. To accommodate smaller azimuth angles, a larger area must be sacrificed, resulting in a smaller fill factor. To solve this problem, two sets of array elements with different frequencies can be introduced into the same array, utilizing the remaining area while still meeting the directivity requirements. Figure 4 As shown, PMUT array elements of different frequencies are arranged alternately with the same element spacing p. This design not only meets the required high directivity under a high fill factor but also integrates two different frequency array elements in the array to achieve more comprehensive functionality, adapting to various needs. Using the above method, the orientation angle of a uniform square array of PMUTs integrating 500kHz and 200kHz array elements is shown in the figure. Figure 5 As shown, the different frequency components in this array all achieve a high directivity of 12°, meeting application requirements. By cross-arranging two frequency PMUTs in the same array, a high fill factor, multi-frequency PMUT array is achieved, which can flexibly meet the needs of different working environments.

[0071] In some embodiments, the second element can be a piezoelectric micromechanical ultrasonic transducer that is circular, just like the first element.

[0072] In some embodiments, the gap of the first array element in the first array structure is a gap formed by four adjacent first array elements, wherein every two adjacent first array elements are adjacent in the row direction or adjacent in the column direction of the first array elements, and the second array element is arranged at the center of the gap.

[0073] In some embodiments, a second array element is arranged in each of the gaps of the first array structure.

[0074] In some embodiments, the first array structure is a square array containing N1 rows of first array elements and N1 columns of first array elements, and the second array is a square array containing N2 rows of second array elements and N2 columns of second array elements, where N1 and N2 are both positive integers.

[0075] In some embodiments, both the first array element and the second array element are circular piezoelectric micromechanical ultrasonic transducers, and the diameters of the first array element and the second array element are different.

[0076] It is understandable that the dimensions of the first array element and the second array element are different, that is, the diameter of the cavity of the first array element and the diameter of the cavity of the second array element are different.

[0077] In some application scenarios, such as Figure 4 As shown, PMUT elements of different frequencies are staggered in the array, with one more row / column element in the outer layer than in the inner layer. The PMUTs of both frequencies have the same element spacing. Typically, the radius of the higher-frequency PMUT is smaller than that of the lower-frequency PMUT, therefore the higher-frequency PMUT is usually located in the inner layer. The directivity specifications of a designed PMUT array with alternating 200kHz and 500kHz PMUTs are shown below. Figure 5 As shown, all achieve a 12° azimuth angle, exhibiting good directionality and meeting the requirement for high directivity.

[0078] As can be seen, in the above scheme, by carrying out a series of array designs on the piezoelectric micromechanical ultrasonic transducer, the desired beamwidth and sidelobe level are obtained by adjusting the number and spacing of array elements, introducing a dual-frequency transducer array, and adjusting the top electrode area to achieve array element amplitude control. This results in a high-directivity, multi-frequency operation, and low sidelobe level array design, improving directivity and meeting the requirements of specific occasions for strong anti-interference capability and long propagation distance.

[0079] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0080] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is used as an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

[0081] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A piezoelectric micromechanical ultrasonic transducer array, characterized in that, include: A first array structure, comprising a plurality of array elements arranged in an array, each of the first array elements being a first piezoelectric micromechanical ultrasonic transducer; In the first array structure, the row spacing and column spacing of the first array element are equal; The number of the first array elements, the row spacing, and the column spacing in the first array structure meet the first preset conditions. The first preset conditions include that the difference between the first orientation angle of the first array structure and the preset first target orientation angle is less than the first preset error value. The first array element is a circular piezoelectric micromechanical ultrasonic transducer, and the cross-section of the cavity of the first piezoelectric micromechanical ultrasonic transducer is circular; The number of first array elements, row spacing, and column spacing in the first array structure are determined according to the orientation angle function, wherein the expression of the function is: In the formula, N is the number of the first array elements in the first array structure; k is the number of sound waves; a is the radius of the cavity cross section; p is the row spacing and column spacing of the first array element in the first array structure; J3 is the third-order form of a Bessel function of the first kind.

2. The piezoelectric micromechanical ultrasonic transducer array as described in claim 1, characterized in that, The first piezoelectric micromechanical ultrasonic transducer includes a support layer, a bottom electrode layer disposed on the support layer, a pressure point layer disposed on the bottom electrode layer, and a top electrode disposed on the pressure point layer. The support layer has a cavity on the side opposite to the top electrode.

3. The piezoelectric micromechanical ultrasonic transducer array as described in claim 2, characterized in that, The number of the first array elements, row spacing, and column spacing in the first array structure are determined based on the cavity size, number of sound waves, and first target direction angle of the first piezoelectric micromechanical ultrasonic transducer.

4. The piezoelectric micromechanical ultrasonic transducer array as described in claim 1, characterized in that, The first array elements of the first array structure form multiple array element rings, and the first array elements in each array element ring are interconnected to form a rectangle; the ratio of the top electrode to the cavity of all the first array elements in each array element ring is the same, and the ratio of all the array element rings of the first array structure satisfies a third preset condition, the third preset condition including the beamwidth of the first array structure being a preset beamwidth and / or the sidelobe level of the first array structure being a preset sidelobe level.

5. The piezoelectric micromechanical ultrasonic transducer array as described in claim 1, characterized in that, It also includes a second array structure, which includes multiple array elements arranged in an array. Each second array element is a second piezoelectric micromechanical ultrasonic transducer. The resonant frequency of the second array structure is different from that of the first array structure. The second array element is located in the gap of the first array element in the first array structure, and the row spacing and column spacing of the first array element in the first array structure are equal; The number of the first array elements, the row spacing, and the column spacing in the first array structure meet the second preset conditions. The second preset conditions include that the difference between the second orientation angle of the second array structure and the preset second target orientation angle is less than the second preset error value.

6. The piezoelectric micromechanical ultrasonic transducer array as described in claim 5, characterized in that, The gap between the first array elements in the first array structure is formed by four adjacent first array elements. Each pair of adjacent first array elements is adjacent in the row direction or in the column direction of the first array elements. The second array elements are arranged at the center of the gap.

7. The piezoelectric micromechanical ultrasonic transducer array as described in claim 6, characterized in that, One of the second array elements is arranged in each of the gaps in the first array structure.

8. The piezoelectric micromechanical ultrasonic transducer array as described in claim 5, characterized in that, The first array structure is a square array containing N1 rows of first array elements and N1 columns of first array elements, and the second array is a square array containing N2 rows of second array elements and N2 columns of second array elements, where N1 and N2 are both positive integers.

9. The piezoelectric micromechanical ultrasonic transducer array as described in claim 5, characterized in that, Both the first array element and the second array element are circular piezoelectric micromechanical ultrasonic transducers, and the diameters of the first array element and the second array element are different.

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