Membrane scanning mirror and design method thereof

Abstract

This application provides a MEMS scanning mirror and its design method, relating to the field of microelectromechanical systems (MEMS) technology, aiming to increase the scanning angle of the scanning mirror, reduce its stress, and improve its resonant frequency. The MEMS scanning mirror includes a reflector, multiple first piezoelectric driving structures, and multiple sets of first elastic elements. The multiple first piezoelectric driving structures are disposed on opposite sides of the reflector along a first direction. Each set of first elastic elements is disposed between two adjacent first piezoelectric driving structures along a second direction. Each first piezoelectric driving structure is connected to the reflector via a first elastic element. The shape of the orthographic projection of the first elastic element onto the reference plane is an irregular geometric curve, which reduces the equivalent rotational stiffness of the first elastic element, increases the scanning angle of the MEMS scanning mirror, and reduces its stress. Furthermore, the irregular geometric curve has diverse and simple orientations, which can improve its resonant frequency, thereby improving the dynamic response speed and stability of the MEMS scanning mirror.

Description

Technical Field

[0001] This application relates to the field of microelectromechanical systems (MEMS) technology, and in particular to a MEMS scanning mirror and its design method. Background Technology

[0002] In related technologies, the scanning angle of a micro-electro-mechanical system (MEMS) scanning mirror is increased by reducing the stiffness of its drive beam. This can be achieved by reducing the width or increasing the length of the drive beam. However, this approach leads to a decrease in the resonant frequency of the scanning mirror, affecting its dynamic response speed and stability. Furthermore, increasing the scanning angle increases stress, making the drive beam more susceptible to fatigue fracture, plastic deformation, or even structural failure, thus impacting the mirror's reliability and lifespan.

[0003] Therefore, how to reduce the stress of the scanning mirror and increase its resonant frequency while ensuring that the scanning mirror maintains a large scanning angle is one of the technical problems that urgently need to be solved. Summary of the Invention

[0004] This application proposes a MEMS scanning mirror and its design method, aiming to increase the scanning angle of the scanning mirror, reduce its stress, and improve its resonant frequency.

[0005] In a first aspect, a MEMS scanning mirror is provided, comprising a reflector, a plurality of first piezoelectric driving structures, and a plurality of sets of first elastic elements. The plurality of first piezoelectric driving structures are disposed on opposite sides of the reflector along a first direction. A portion of the first piezoelectric driving structures located on the same side of the reflector are spaced apart along a second direction. Both the first and second directions are parallel to the reflector and intersect each other. The plurality of sets of first elastic elements are disposed between two adjacent first piezoelectric driving structures disposed along the second direction. Each set of first elastic elements includes two first elastic elements, which are spaced apart along the second direction. Each first piezoelectric driving structure is connected to the reflector via a first elastic element. The orthographic projection of the first elastic element onto a reference plane has an irregular geometric curve shape. The reference plane is parallel to the reflector. The irregular geometric curve is... Where I represents an irregular geometric curve, m represents the dimension of the first piezoelectric drive structure in the first direction, n represents half the dimension of the interval between two adjacent first piezoelectric drive structures located on the same side of the reflector in the second direction, and x represents... At any point in the region, C represents the centerline of the irregular geometric curve, and r represents half the distance between the two boundaries of the first elastic element in the first direction.

[0006] In this embodiment, a first elastic element with an irregular geometric curve is provided between two adjacent first piezoelectric driving structures. Since the first elastic element has a folded portion, and the aforementioned folded portion has few folds in the first direction or diverse and simple paths in the second direction, the equivalent rotational stiffness of the first elastic element can be reduced within a limited chip area, making the scanning angle more sensitive to the driving force. This enables the MEMS scanning mirror to achieve large-angle scanning. At the same time, the trend of the aforementioned first elastic element can change the main mode shape and equivalent stiffness direction distribution of the overall structure of the MEMS scanning mirror, thereby improving the problems of low resonant frequency and high stress of the MEMS scanning mirror. Thus, while increasing the scanning angle of the MEMS scanning mirror, its stress can be reduced and its resonant frequency can be increased, thereby improving the dynamic response speed and stability of the MEMS scanning mirror. This allows it to be applied in applications with high requirements for scanning speed and accuracy, such as real-time detection of lidar and high frame rate optical imaging.

[0007] In some embodiments, the distance between the two side boundaries of the first elastic member in the first direction is 10µm to 30µm.

[0008] In some embodiments, the MEMS scanning mirror further includes a support frame, a plurality of second piezoelectric driving structures, and a plurality of sets of second elastic elements. The support frame is disposed around the reflector along its circumference and is spaced apart from the reflector. The plurality of first elastic elements are located between the support frame and the reflector. The plurality of second piezoelectric driving structures are disposed on both sides of the support frame along a second direction. Among the plurality of second piezoelectric structures, some second piezoelectric driving structures located on the same side of the support frame are spaced apart along a first direction. Each set of second elastic elements includes two second elastic elements, and the two second elastic elements are spaced apart along the first direction. Each second piezoelectric driving structure is connected to the support frame via a second elastic element. The support frame includes two first sub-parts and two second sub-parts, with the first sub-parts extending along the first direction and the second sub-parts extending along the second direction. Along the second direction, the side of the first sub-parts closest to the reflector contacts the first piezoelectric driving structure. Along the second direction, the second sub-parts contact the side of the second piezoelectric driving structure closest to the reflector.

[0009] In some embodiments, the second elastic element has the same structure as the first elastic element.

[0010] Secondly, a design method for a MEMS scanning mirror is provided, which is applied to the MEMS scanning mirror of the first aspect. This design method includes determining a target region and generating multiple centerlines within the target region based on a path planning algorithm. The target region is located between two adjacent piezoelectric drive structures. An initial population is formed based on a preset width and multiple centerlines. The initial population includes multiple initial irregular geometric curves. Based on a genetic algorithm, a phased strategy is used to process the initial population to obtain multiple irregular geometric curves. The processing includes crossover and mutation. The irregular geometric curves characterize the contour of the elastic element. Parametric modeling and analysis are performed based on the multiple irregular geometric curves to obtain multiple sets of performance parameters for the MEMS scanning mirror. Each set of performance parameters for the multiple irregular geometric curves corresponds one-to-one with the performance parameters of the multiple sets of MEMS scanning mirrors. The performance parameters of each set of MEMS scanning mirrors include scanning angle, stress, and resonant frequency. The multiple irregular geometric curves are evaluated based on an evaluation function to obtain a target irregular geometric curve. The performance parameters of the MEMS scanning mirror corresponding to the target irregular geometric curve are the target performance parameters. The irregular geometric curve is... Where I represents an irregular geometric curve, The target area is represented by x, any point within the target area is represented by C, the centerline of the irregular geometric curve is represented by r, and half of the preset width is represented by r.

[0011] In this embodiment, a genetic algorithm is used to optimize the initial population at different stages using different strategies (such as different crossover probabilities, mutation probabilities, etc.) to obtain multiple irregular geometric curves, i.e., the design profiles of the elastic element. The optimal irregular geometric curve, i.e., the target irregular geometric curve, is selected from the aforementioned multiple irregular geometric curves using a rating function. When the elastic element (such as the first elastic element) prepared according to the target irregular geometric curve is applied to the MEMS scanning mirror, the MEMS scanning mirror can maintain a large scanning angle while having low stress and high resonant frequency. This can improve the dynamic response speed and stability of the MEMS scanning mirror, making it applicable to applications with high requirements for scanning speed and accuracy.

[0012] In some embodiments, based on a genetic algorithm, a phased strategy is employed to process the initial population to obtain multiple irregular geometric curves. This includes performing crossover and mutation processing on the initial population based on a first crossover probability and a first mutation probability to obtain multiple first individuals. Then, performing crossover and mutation processing on the multiple first individuals based on a second crossover probability and a second mutation probability to obtain multiple second individuals. Finally, performing crossover and mutation processing on the multiple second individuals based on a third crossover probability and a third mutation probability to obtain multiple irregular geometric curves. The second crossover probability is greater than the first crossover probability and less than the third crossover probability. The second mutation probability is less than the first mutation probability and greater than the third mutation probability.

[0013] In some embodiments, the above-described MEMS scanning mirror design method further includes constructing an evaluation function based on the performance parameters of the MEMS scanning mirror. The averaging function is:

[0014] Where Evaluate represents the evaluation score of the irregular geometric curve, α represents the trade-off coefficient between the maximum scanning angle and the resonant frequency, angle1 represents the maximum scanning angle of the MEMS scanning mirror at the inner frame angle, and angle2 represents the maximum scanning angle of the MEMS scanning mirror at the outer frame angle. This represents the resonant frequency corresponding to the scanning angle 1 of the MEMS scanning mirror. This represents the resonant frequency corresponding to the scanning angle 2 of the MEMS scanning mirror.

[0015] In some embodiments, before evaluating multiple irregular geometric curves based on an evaluation function to obtain a target irregular geometric curve, the method further includes obtaining an initial target irregular geometric curve based on the stress of the MEMS scanning mirror corresponding to each irregular geometric curve and a preset stress. Evaluating multiple irregular geometric curves based on an evaluation function to obtain the target irregular geometric curve includes evaluating the initial target irregular geometric curve based on the evaluation function to obtain the target irregular geometric curve.

[0016] In some embodiments, before performing parametric modeling and analysis based on multiple irregular geometric curves to obtain multiple sets of performance parameters for the MEMS scanning mirror, the method further includes smoothing the irregular geometric curves using a smoothing algorithm to obtain a first irregular geometric curve. Performing parametric modeling and analysis based on multiple irregular geometric curves to obtain multiple sets of performance parameters for the MEMS scanning mirror includes performing parametric modeling and analysis based on multiple first irregular geometric curves to obtain multiple sets of performance parameters for the MEMS scanning mirror. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this application, the accompanying drawings used in some embodiments of this application will be briefly described below. Obviously, the drawings described below are only drawings of some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings. In addition, the drawings described below can be regarded as schematic diagrams and are not actual dimensions of the products or actual processes of the methods involved in the embodiments of this application.

[0018] Figure 1 A schematic diagram of the structure of a MEMS scanning mirror provided in an embodiment of this application: Figure 2A schematic diagram of a MEMS scanning mirror without elastic elements provided in an embodiment of this application; Figure 3 for Figure 2 A magnified view of the MEMS scanning mirror at point P'; Figure 4 for Figure 1 A magnified view of the MEMS scanning mirror at point P; Figure 5 This is a schematic diagram of another MEMS scanning mirror provided in an embodiment of this application; Figure 6 A flowchart illustrating a design method for a MEMS scanning mirror provided in this application embodiment; Figure 7 A schematic diagram of the centerline of an initial irregular geometric curve provided in an embodiment of this application; Figure 8 A schematic diagram of an initial irregular geometric curve provided for an embodiment of this application; Figure 9 A flowchart for forming an irregular geometric curve is provided as an example of this application; Figure 10 A schematic diagram of irregular geometric curve pixelation provided in an embodiment of this application; Figure 11 To Figure 10 A schematic diagram showing the result obtained after format conversion of irregular geometric curves in the image; Figure 12 for Figure 10 A schematic diagram of irregular geometric curves in simulation software; Figure 13 A flowchart for obtaining an initial target irregular geometric curve is provided in an embodiment of this application; Figure 14 A schematic diagram of an irregular geometric curve provided for an embodiment of this application; Figure 15 To Figure 14 An enlarged view of the result at point Q after smoothing the non-regular geometric curve; Figure 16 A flowchart illustrating another design method for a MEMS scanning mirror provided in this application embodiment. Detailed Implementation

[0019] The technical solutions in some embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application are within the scope of protection of this application.

[0020] Unless the context otherwise requires, throughout the specification and claims, the term "comprising" is interpreted as open and encompassing, that is, "including, but not limited to".

[0021] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this application, unless otherwise stated, "a plurality of" means two or more.

[0022] In describing some embodiments, the term "connection" and its derivative expressions may be used. The term "connection" should be interpreted broadly; for example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a direct connection or an indirect connection through an intermediate medium. For example, in describing some embodiments, the term "connection" may be used to indicate that two or more components have direct physical or electrical contact with each other.

[0023] In addition, the use of “based on” implies openness and inclusivity, because processes, steps, calculations or other actions “based on” one or more of the stated conditions or values ​​may in practice be based on additional conditions or values ​​beyond those stated.

[0024] It should be understood that when a layer or element is referred to as being on another layer or substrate, it can mean that the layer or element is directly on the other layer or substrate, or that there is an intermediate layer between the layer or element and the other layer or substrate.

[0025] This document describes exemplary embodiments with reference to cross-sectional views, which are intended as idealized exemplary drawings. In the drawings, the thickness of the layers and the area of ​​the regions are enlarged for clarity. Therefore, variations in shape relative to the drawings are contemplated due to, for example, manufacturing techniques and / or tolerances. Thus, exemplary embodiments should not be construed as limited to the shapes of the regions shown herein, but rather include shape deviations caused, for example, by manufacturing processes. For example, etched areas shown as rectangular would typically have curved features. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to show the actual shapes of the areas of the device, nor are they intended to limit the scope of the exemplary embodiments.

[0026] In related technologies, the scanning angle of a micro-electro-mechanical system (MEMS) scanning mirror is increased by reducing the stiffness of its drive beam. This can be achieved by reducing the width or increasing the length of the drive beam. However, this approach leads to a decrease in the resonant frequency of the scanning mirror, affecting its dynamic response speed and stability. Furthermore, increasing the scanning angle increases stress, making the drive beam more susceptible to fatigue fracture, plastic deformation, or even structural failure, thus impacting the mirror's reliability and lifespan.

[0027] Therefore, how to reduce the stress of the scanning mirror and increase its resonant frequency while ensuring that the scanning mirror maintains a large scanning angle is one of the technical problems that urgently need to be solved.

[0028] To address the aforementioned problems, embodiments of this application provide a MEMS scanning mirror. Figure 1 This is a schematic diagram of the structure of a MEMS scanning mirror provided in an embodiment of this application.

[0029] See Figure 1 The aforementioned MEMS scanning mirror 100 includes a reflector 1, multiple first piezoelectric drive structures 2, and multiple sets of first elastic elements 3.

[0030] Among them, the reflector 1 is used to realize the scanning and control of the beam. For example, the beam propagation direction can be changed by the physical swing of the reflector 1 to realize the scanning and control of the beam.

[0031] The first piezoelectric drive structure 2 described above can convert electrical signals into mechanical deformation through the inverse piezoelectric effect to drive the reflector 1 to deflect, thereby realizing the scanning and control of the beam.

[0032] The first piezoelectric drive structure 2 here may include a first electrode layer, a piezoelectric material layer, a second electrode layer and a base layer (these layers are not shown in the figures of this application embodiment) stacked sequentially along the Z direction. By applying an electrical signal to the first electrode layer and the second electrode layer, the piezoelectric material layer is deformed by utilizing the inverse piezoelectric effect of the piezoelectric material layer, thereby causing the base layer and components such as the reflector 1 connected to the base layer to deflect, so as to realize the mechanical movement required for beam scanning, etc.

[0033] See Figure 1 The aforementioned multiple first piezoelectric drive structures 2 can be disposed on opposite sides of the reflector 1 along the first direction X.

[0034] See Figure 1Among the aforementioned plurality of first piezoelectric drive structures 2, some of the first piezoelectric drive structures 2 located on the same side of the reflector 1 can be spaced apart along the second direction Y, so that an elastic element (i.e. a drive beam) can be subsequently provided at the interval between two first piezoelectric drive structures 2, thereby transmitting the driving force generated by the first piezoelectric drive structure 2 to the reflector 1.

[0035] For example, Figure 1 In the MEMS scanning mirror 100, there are four first piezoelectric driving structures 2. Along the first direction X, two of the first piezoelectric driving structures 2 are located on the upper side, and along the second direction Y, there is a gap between the two first piezoelectric driving structures 2.

[0036] The first direction X and the second direction Y are both parallel to the reflector 1, and the first direction X and the second direction Y intersect.

[0037] See Figure 1 Each set of first elastic elements 3 is disposed between two adjacent first piezoelectric drive structures 2 along the second direction Y, that is, disposed at the interval between the two first piezoelectric drive structures 2.

[0038] The first elastic element 31 here, also known as the drive beam, is used to transmit the driving force transmitted by the first piezoelectric drive structure 2, and can also provide a rotation axis and mechanical support for the reflector 1.

[0039] See Figure 1 Each set of first elastic elements 3 includes two first elastic elements 31, and the two first elastic elements 31 are spaced apart along the second direction Y to ensure that the two first elastic elements 31 can deform independently, thereby avoiding interference between the deformation of one first elastic element 31 and the other first elastic element 31, which could lead to problems such as torque imbalance, mirror tilting of the reflector 1, and torsion jamming.

[0040] See Figure 1 Each first piezoelectric drive structure 2 can be connected to the reflector 1 through the first elastic element 31, that is, one end of the first elastic element 31 is connected to the first piezoelectric drive structure 2, and the other end is connected to the reflector 1.

[0041] See Figure 1 The shape of the orthographic projection of the first elastic element 31 onto the reference plane O can be an irregular geometric curve.

[0042] The reference plane O here is parallel to the reflecting mirror 1.

[0043] The above irregular geometric curves can be represented by the following formula: {x∈m×n:dist(x,C)≤r} Where m represents the dimension of the first piezoelectric drive structure 2 in the first direction X, n represents half the dimension of the interval between two adjacent first piezoelectric drive structures 2 located on the same side of the reflector 1 in the second direction Y, x represents any point in the m×n region, C represents the center line of the irregular geometric curve, and r represents half the distance between the two boundaries of the first elastic member 31 in the first direction X.

[0044] See Figure 1 The aforementioned irregular geometric curves include folded portions (i.e., serpentine portions). Compared to the first elastic element 31 in related technologies, the aforementioned folded portions have fewer folds in the first direction X, meaning the folded portions have a simpler orientation in the second direction Y. Thus, the equivalent rotational stiffness of the first elastic element 31 can be reduced within a limited chip area (i.e., the interval area between the two first piezoelectric drive structures 2), making the scanning angle more sensitive to the driving force. This enables the MEMS scanning mirror 100 to achieve large-angle scanning. At the same time, it can also avoid the problem of reduced resonant frequency of the MEMS scanning mirror 100 due to the large number of folds in the first direction X or the complex orientation in the second direction Y of the first elastic element 31, thereby improving its resonant frequency.

[0045] Figure 2 This is a schematic diagram of a MEMS scanning mirror without elastic elements provided in an embodiment of this application. Figure 3 for Figure 2 A magnified view of the MEMS scanning mirror at point P'.

[0046] See Figure 2 and Figure 3 The spaced region between the two first piezoelectric drive structures 2 located on the same side of the reflector 1 can be pixelated, that is, the aforementioned spaced region is divided into multiple square grids with a side length of 1µm, and each grid can represent a pixel.

[0047] The above-mentioned interval region can be divided into two sub-interval regions P', and each sub-interval region P' corresponds to a first elastic element 31 for illustration.

[0048] In the above expression for irregular geometric curves, m represents the number of square grids formed after the sub-spacement region P' is divided in the first direction X, for example, 640; n represents the number of square grids formed after the sub-spacement region P' is divided in the second direction Y, for example, 640; and x represents any one of the square grids in the sub-spacement region P'.

[0049] It is understood that the aforementioned MEMS scanning mirror 100 can be a single-axis scanning mirror, that is, it can rotate along a set axis to achieve scanning, for example, rotating along the first direction X as the axis.

[0050] It is understood that in this embodiment, a first elastic element 31 with an irregular geometric curve is provided between two adjacent first piezoelectric drive structures 2. Since the first elastic element 31 has a folded portion, and the aforementioned folded portion has few folds in the first direction X or diverse and simple directions in the second direction Y, the equivalent rotational stiffness of the first elastic element 31 can be reduced within a limited chip area, making the scanning angle more sensitive to the driving force, thereby enabling the MEMS scanning mirror 100 to achieve large-angle scanning. At the same time, the trend of the aforementioned first elastic element 31 can change the main mode shape and equivalent stiffness direction distribution of the overall structure of the MEMS scanning mirror 100, thereby improving the problems of low resonant frequency and high stress of the MEMS scanning mirror 100. Thus, while increasing the scanning angle of the MEMS scanning mirror 100, its stress can be reduced and its resonant frequency can be increased, thereby improving the dynamic response speed and stability of the MEMS scanning mirror 100, making it applicable to applications with high requirements for scanning speed and accuracy, such as real-time detection of lidar and high frame rate optical imaging.

[0051] Figure 4 for Figure 1 A magnified view of the MEMS scanning mirror at point P.

[0052] In some embodiments, see Figure 4 The distance W between the two boundaries of the first elastic 31 in the first direction X can be 10µm~30µm.

[0053] For example, Figure 4 In the first direction X, the distance W between the upper and lower boundaries of the first elastic member 31.

[0054] For example, the distance W between the two sides of the first elasticity 31 in the first direction X can be 10µm, 15µm, 20µm, 25µm, or 30µm.

[0055] In this way, by controlling the distance W between the two sides of the first elastic element 31 in the first direction X (i.e. the width of the first elastic element 31) to be 10µm~30µm, the scanning angle and resonant frequency of the MEMS scanning mirror 100 can be balanced. That is, while ensuring the material strength of the first elastic element 31, the scanning angle of the MEMS scanning mirror 100 can be further increased, and at the same time, the situation of its resonant frequency being greatly reduced can be avoided, so as to ensure that it has a high resonant frequency.

[0056] Figure 5 This is a schematic diagram of another MEMS scanning mirror provided in an embodiment of this application.

[0057] In some embodiments, see Figure 5The aforementioned MEMS scanning mirror 100 also includes a support frame 4, multiple second piezoelectric drive structures 5, and multiple sets of second elastic elements 6.

[0058] The support frame 4 provides physical support for the reflector 1, the first piezoelectric drive structure 2, and the second piezoelectric drive structure 5. It can also work in conjunction with the first piezoelectric drive structure 2 and the second piezoelectric drive structure 5 to limit the movement of the reflector 1, for example, to control the reflector 1 to perform scanning motion along a set axis.

[0059] See Figure 5 The aforementioned support frame 4 can be arranged around the reflector 1 along its circumference and is spaced apart from the reflector 1, for example, Figure 5 In the middle, a rectangular reflector 1 and a support frame 4 are arranged around the aforementioned reflector 1, and there is a distance between them and the boundary of the reflector 1.

[0060] See Figure 5 Multiple sets of first elastic elements 3 can be arranged between the support frame 4 and the reflector 1 so that the support frame 4 can be used to fix the first piezoelectric drive structure 2. At the same time, the support frame 4 and the first piezoelectric drive structure 2 can work together to limit the movement of the reflector 1.

[0061] See Figure 5 The aforementioned plurality of second piezoelectric drive structures 5 can be disposed on both sides of the support frame 4 along the second direction Y. For example, they can be disposed on the left and right sides of the support frame 4 along the second direction Y.

[0062] The structure and function of the second piezoelectric drive structure 5 here are the same as those of the first piezoelectric drive structure 2, and will not be described again here.

[0063] Among the aforementioned plurality of second piezoelectric structures 5, some of the second piezoelectric drive structures 5 located on the same side of the support frame 4 can be spaced apart along the first direction X, that is, there is a gap between two adjacent second piezoelectric drive structures 5 located on the same side of the support frame 4, so that elastic elements can be subsequently installed at the aforementioned gap positions to transmit the driving force generated by the second piezoelectric drive structure 5.

[0064] See Figure 5 Each set of second elastic elements 6 may include two second elastic elements 61, and the two second elastic elements 61 may be spaced apart along the first direction X to ensure that the two second elastic elements 61 can deform independently, thereby avoiding mutual interference when the two second elastic elements 61 deform, so as to ensure that the reflector 1 runs stably according to the set axis.

[0065] Each of the above-mentioned second piezoelectric drive structures 5 can be connected to the support frame 4 through the second elastic member 61. That is, one end of the second elastic member 61 can be connected to the second piezoelectric drive structure 5, and the other end can be connected to the support frame 4, so that the driving force generated by the second piezoelectric drive structure 5 can be transmitted to the support frame 4 through the second elastic member 61, thereby driving the support frame 4, as well as the reflector 1 and the first piezoelectric drive structure 2 connected to the support frame 4 to rotate.

[0066] See Figure 5 The aforementioned support frame 4 may include two first sub-parts 41 and two second sub-parts 42, with the first sub-parts 41 extending along a first direction X and the second sub-parts 42 extending along a second direction Y.

[0067] Along the second direction Y, the side of the first sub-part 41 near the reflector 1 is in contact with the first piezoelectric drive structure 2. That is, the first sub-part 41 is used to fix one end of the first elastic member 31, and under the action of the driving force, the first sub-part 41 can rotate together with the reflector 1, the first piezoelectric drive structure 2, etc.

[0068] Along the second direction Y, the second sub-part 42 contacts the side of the second piezoelectric drive structure 5 near the reflector 1, that is, the second sub-part 42 is used to fix one end of the second elastic member 61, and under the action of the driving force, the second sub-part 42 can rotate together with the second piezoelectric drive structure 2.

[0069] It is understood that the aforementioned MEMS scanning mirror 100 can be a dual-axis scanning mirror, that is, it can rotate along two mutually perpendicular axes to achieve pitch or yaw scanning.

[0070] In this way, by setting the support frame 4, the second elastic element 61, and the second piezoelectric drive structure 5 in the MEMS scanning mirror 100, on the one hand, the scanning angle of the MEMS scanning mirror 100 in one axis (e.g., the first direction X) can be increased by using the first elastic element 31, thereby increasing its resonant frequency. On the other hand, the second elastic element 61 and the second piezoelectric drive structure 5 can work together to control the MEMS scanning mirror 100 to perform scanning motion in another axis (e.g., the second direction Y). In this way, the MEMS scanning mirror 100 can meet more complex and diverse application requirements, thereby improving its market competitiveness.

[0071] In some embodiments, the structure of the second elastic element 61 can be the same as that of the first elastic element 31. In this way, the scanning angle of the MEMS scanning mirror 100 in both axes can be increased by using the first elastic element 31 and the second elastic element 61 respectively, and its stress can be reduced and its resonant frequency can be increased. At the same time, it can save time and manufacturing costs and improve the production efficiency.

[0072] For example, see Figure 5 The shape of the second elastic element 61 on the reference plane O can also be an irregular geometric curve, that is, the shape of the second elastic element 61 on the reference plane O can also be represented by the formula {x∈m×n:dist(x,C)≤r}.

[0073] Where m represents the dimension of the second piezoelectric drive structure 5 in the second direction Y, n represents half the dimension of the interval between two adjacent second piezoelectric drive structures 5 located on the same side of the support frame 4 in the first direction X, x represents any point in the m×n region, C represents the center line of the irregular geometric curve, and r represents half the distance between the two boundaries of the second elastic member 61 in the second direction Y.

[0074] For example, see Figure 5 When the shapes of the orthographic projections of the first elastic element 31 and the second elastic element 61 on the reference plane O are both irregular geometric curves, the structures of the first elastic element 31 and the second elastic element 61 can be different to adapt to the needs of different scanning angles in different axes. This allows for more precise control of the operating characteristics of the MEMS scanning mirror 100 in both axes, thereby improving its overall performance and adaptability in complex and variable application scenarios.

[0075] This application also provides a design method for a MEMS scanning mirror. Figure 6 A flowchart illustrating a design method for a MEMS scanning mirror provided in this application embodiment. Figure 7 This is a schematic diagram of the centerline of an initial irregular geometric curve provided in an embodiment of this application.

[0076] See Figure 6 The above design method includes the following steps S1 to S5: Step S1: See Figure 2 and Figure 7 The target region P' is determined, and multiple center lines are generated within the target region based on the path planning algorithm.

[0077] For example, see Figure 1 , Figure 2 , Figure 3 and Figure 5 , See Figure 2 The target area P' is located between two adjacent piezoelectric drive structures so that an elastic element (such as the first elastic element 31) can be installed in this area.

[0078] For example, Figure 2 In the middle, along the second direction Y, between two adjacent first piezoelectric drive structures 2, or Figure 5 In the middle, along the first direction X, between two adjacent second piezoelectric drive structures 5.

[0079] The target region P' here is half of the interval region between two adjacent piezoelectric drive structures.

[0080] The above-mentioned interval region can be divided into two sub-interval regions P', and each sub-interval region P' corresponds to a first elastic element 31 for illustration.

[0081] For example, see Figure 3 and Figure 7 After determining the target region P', the target region P' can be pixelated, and then a center line can be generated within the pixelated target region P'. For example, the target region P' can be divided into multiple square grids with a side length of 1µm, and each grid can represent a pixel.

[0082] This allows for the design of the first elastic element 31 and the second elastic element 61 at the micrometer level, ensuring that the performance of the first elastic element 31 and the second elastic element 61 is not affected when they are fabricated using micro-nano processing technology, thereby improving the reliability of the MEMS scanning mirror 100.

[0083] For example, in the target region P', a random path algorithm can be used to move along the second direction Y from one of the two adjacent boundaries of the two first piezoelectric driving structures 2 to the other boundary, resulting in a broken line (see...). Figure 7 ), that is, the centerline of the initial irregular geometric curve.

[0084] The centerline of the aforementioned initial irregular geometric curve can be represented by a series of discrete points, i.e., the vertices of the broken line, using the following formula: , Where C represents a broken line, This represents the vertices on the broken line.

[0085] For example, the discrete tangent vectors of each vertex of the polyline can also be calculated using the following formula:

[0086] , in, This represents the discrete tangent vector of the interior vertex of the polyline. Indicates the internal vertices of the polyline. This represents the (k+1)th vertex. This represents the (k-1)th vertex. This represents the discrete tangent vector of the first vertex of the polyline. Indicates the second vertex. Represents the first vertex. This represents the discrete tangent vector of the last vertex of the polyline.

[0087] Figure 8 This is a schematic diagram of an initial irregular geometric curve provided for an embodiment of this application.

[0088] Step S2: See Figure 8 An initial population is formed based on a preset width and multiple center lines.

[0089] For example, Figure 8 In the middle, based on the center line, it is extended to both sides in a direction perpendicular to the center line to obtain an initial irregular geometric curve.

[0090] The preset width here is the distance between the two boundaries of the first elastic member 31 in the first direction X, or the distance between the two boundaries of the second elastic member 61 in the second direction Y.

[0091] For example, the preset width can be 10µm to 30µm, such as 10µm, 15µm, 20µm, 25µm, or 30µm.

[0092] In this way, by designing a preset width, the spacing W (i.e. the width of the first elastic element 31) between the two sides of the first elastic element 31 in the first direction X can be controlled to be 10µm~30µm. This can balance the scanning angle and resonant frequency of the MEMS scanning mirror 100. That is, while ensuring the material strength of the first elastic element 31, the scanning angle of the MEMS scanning mirror 100 can be further increased, while avoiding a significant decrease in its resonant frequency, so as to ensure that it has a high resonant frequency.

[0093] The initial population mentioned above includes multiple initial irregular geometric curves, and each initial irregular geometric curve is an initial individual.

[0094] For example, the right normal vector of each vertex of the polyline and the boundary points on both sides can also be calculated separately.

[0095] For example, the right normal vector corresponding to each vertex of the polyline can be calculated using the following formula: , in, Let represent the right normal vector of the k-th vertex of the polyline.

[0096] The boundary points on both sides of each vertex of the polyline can be calculated using the following formula: , in, Represents the two boundary points of the k-th vertex. Let r represent the k-th vertex, and let r represent the offset between the k-th vertex and the corresponding boundary point.

[0097] The aforementioned initial irregular geometric curve can be represented by the following formula: , Where I represents an irregular geometric curve, m×n represents the target region P', x represents any point in the target region P', C represents the center line of the irregular geometric curve, and r represents half of the distance between the two sides of the first elastic member 31 in the first direction X, that is, half of the preset width.

[0098] The above formula can also be expressed as: , Vertex Represented as A, Let B be the distance from x to line segment AB. The distance from x to line segment AB can be calculated using the following formula:

[0099] , Where t represents a parameter indicating the relative position of point x along the direction of vector v. This means restricting the value of t to... Within the range.

[0100] The projection point of x above is Then the distance from point x to AB is .

[0101] The distance from x to AB can be used to determine whether point x is a point that forms an irregular geometric curve. The judgment expression is as follows:

[0102] If point x satisfies the above judgment expression, then set the value of the grid where point x is located to 1; otherwise, set the value to 0.

[0103] For example, the number H of the aforementioned initial irregular geometric curves formed can be determined based on the time and time threshold at which each initial irregular geometric curve is formed, i.e., the number of initial individuals in the initial population.

[0104] The time threshold here is the total time acceptable to researchers for forming the initial irregular geometric curve.

[0105] For example, the time required to form each initial irregular geometric curve is seconds, time threshold is ,but .

[0106] The value of H here can be 50, so as to provide sufficient data for subsequent optimization of the initial irregular geometric curve using the genetic algorithm, and avoid the problem that the optimization result will fall into a local optimum due to insufficient data.

[0107] Alternatively, by way of example, the number of initial irregular geometric curves H can be determined by comprehensively considering factors such as the number of square grids into which the target region P' is divided, computational scale, computation time, memory resources, and hardware costs. This application does not impose any restrictions on this.

[0108] Step S3: Based on the genetic algorithm, a phased strategy is used to process the initial population to obtain multiple irregular geometric curves.

[0109] The processing here can include crossover and mutation to optimize the initial population at different stages, resulting in irregular geometric curves.

[0110] The aforementioned irregular geometric curves can characterize the contour of the elastic element. For example, the elastic element can be fabricated based on the irregular geometric curves.

[0111] For example, different randomness, namely crossover probability and mutation probability, can be introduced at different stages to search for the optimal solution step by step. This can avoid the problem of quickly getting trapped in local optima, increase the probability of finding the global optimal solution, and save computational resources.

[0112] The above irregular geometric curve can be represented as: Where I represents an irregular geometric curve, The target area is represented by x, any point within the target area is represented by C, the center line of the irregular geometric curve is represented by r, and half of the preset width is represented by r.

[0113] Figure 9 This is a flowchart for forming an irregular geometric curve, which is provided as a practical example of this application.

[0114] For example, see Figure 9 The aforementioned step S3 further includes the following steps S31 to S33: Step 31: Perform crossover and mutation processing on the initial population based on the first crossover probability and the first mutation probability to obtain multiple first individuals.

[0115] That is, in the first stage, the first crossover probability is used to cross over any two initial individuals (i.e., two initial irregular geometric curves) in the initial population. Then, the first mutation probability is used to mutate the initial individuals after the crossover process to obtain multiple first individuals.

[0116] For example, first set two intersection points, swap the values ​​(e.g., binary encoded values) of the two initial individuals at the aforementioned two intersection points to complete the crossover operation. Then, randomly set a mutation point and perform an inversion operation on the value of the initial individual after the crossover process at that mutation point to obtain the first individual.

[0117] The first volume mentioned above is the initial irregular geometric curve after the first stage of optimization.

[0118] For example, the aforementioned multiple first individuals may include some of the initial individuals in the initial population, and these initial individuals may continue to undergo a second stage of crossover and mutation processing with the initial individuals after crossover and mutation processing.

[0119] For example, individuals can be sorted according to their fitness values ​​and the fitness values ​​of the initial individuals after crossover and mutation, and the top H individuals can be selected as the first individuals to participate in subsequent processing.

[0120] The first stage mentioned above can be determined based on the total number of iterations. That is, the maximum number of iterations can be divided into three equal parts, each representing a stage. For example, when the maximum number of iterations is 15, the first 5 iterations are the first stage.

[0121] The number of iterations here refers to the total number of times the initial population completes operations such as crossover and mutation to generate a new generation of individuals, and repeats this process until the termination condition is met (such as reaching the upper limit of the number of iterations).

[0122] The first crossover probability and the first mutation probability mentioned above can be calculated using the following formula:

[0123] , in, Indicates the probability of mutation. Represents the maximum value of the mutation probability. Let represent the minimum mutation probability, d represent the number of iterations, and D represent the maximum number of iterations. Indicates the crossover probability. Indicates the maximum crossover probability. This represents the minimum crossover probability. An index representing the steepness of the adjustment curve, with a value of .

[0124] For example, the first stage can also be determined based on the fitness value of the first individual and a first fitness threshold, that is, the stage in which the fitness value of the best first individual (the one with the highest fitness value among all first individuals) is less than the first fitness threshold is defined as the first stage.

[0125] Step S32: Perform crossover and mutation processing on multiple first individuals based on the second crossover probability and the second mutation probability to obtain multiple second individuals.

[0126] For example, the aforementioned plurality of second bodies may include portions of the first body.

[0127] Step S33: Perform crossover and mutation processing on multiple second individuals based on the third crossover probability and the third mutation probability to obtain multiple irregular geometric curves.

[0128] The second crossover probability is greater than the first crossover probability and less than the third crossover probability. The second mutation probability is less than the first mutation probability and greater than the third mutation probability.

[0129] Thus, in the first stage, a higher first mutation probability and a lower first crossover probability are achieved. The high mutation probability can enhance population diversity and expand the search range of the solution space by introducing random perturbations, while the low crossover probability can prevent high-quality genes from being destroyed prematurely, thereby strengthening the global exploration capability and reducing the risk of getting trapped in local optima. In the second stage, the mutation probability is reduced (i.e., the second mutation probability is obtained) and the crossover probability is increased (i.e., the second crossover probability is obtained) so that information exchange between individuals can be promoted through crossover operations, accelerating the spread of high-quality genes. At the same time, moderate mutation is maintained to keep the population active, achieving a dynamic balance between global search and local development, and guiding the population to converge toward the potential optimal region.

[0130] Furthermore, in the third stage, the mutation probability is further reduced (i.e., the third mutation probability) and the crossover probability is increased (i.e., the third crossover probability). The low mutation probability can reduce random disturbances and make the search focus on the vicinity of the current optimal solution, while the high crossover probability can achieve high-precision local search by recombining the gene fragments of high-quality individuals, and finally drive the algorithm to converge stably to the global optimal solution.

[0131] In this way, the initial population is processed in stages, including crossover and mutation, and different crossover and mutation probabilities are used in each stage to gradually search for the optimal solution. This can avoid the problem of quickly getting trapped in local optima, increase the probability of finding the global optimal solution, and save computational resources.

[0132] Step S4: Perform parametric modeling and analysis based on multiple irregular geometric curves to obtain multiple sets of performance parameters of the MEMS scanning mirror 100.

[0133] For example, irregular geometric curves can be used in conjunction with simulation software for parametric modeling and analysis. During the simulation process, the scanning angle, stress, resonant frequency and other performance parameters of the MEMS scanning mirror 100 with the first elastic element 31 designed according to each irregular geometric curve can be collected.

[0134] Figure 10 This is a schematic diagram of pixelation of an irregular geometric curve provided in an embodiment of this application. Figure 11 To Figure 10 A schematic diagram showing the result obtained after format conversion of irregular geometric curves in the image. Figure 12 for Figure 10 A schematic diagram of irregular geometric curves in simulation software.

[0135] See Figure 9 When the aforementioned irregular geometric curve is presented within the target region P', it can also be represented by the following two-dimensional matrix:

[0136] , Where G represents the pixelated irregular geometric curve. This represents the value of any point in the target region P', which can be 0 or 1. m represents the number of rows in the target region P', and n represents the number of columns in the sub-interval region P'.

[0137] For example, see Figure 10 The pixelated irregular geometric curves are converted into Graphics Exchange Format (DXF) files or comma-separated value files (CSV) to meet the input requirements of simulation software, so that the simulation software can directly call them.

[0138] For example, you can use MATLAB / Python to write scripts to convert pixelated irregular geometric curves into vectorized coordinate data, and then export them as DXF or CSV files.

[0139] When converting pixelated irregular geometric curves into vectorized coordinate data, this application can utilize the following formula to achieve coordinate transformation:

[0140] , in, This represents the coordinates of a pixel after transformation in the X direction, where i represents the row index of the pixel. This represents the actual physical size of a pixel in the X direction, where 0.5 indicates pixel center positioning, and m represents the total row height. This represents the coordinates of a pixel after transformation in the Y direction, where j represents the column index of the pixel. It represents the actual physical size of a pixel in the Y direction.

[0141] For the visualization results of the above irregular geometric curves in the simulation software, please refer to [link / reference]. Figure 11 .

[0142] The aforementioned irregular geometric curves correspond one-to-one with the performance parameters of multiple sets of MEMS scanning mirrors 100, that is, each irregular geometric curve corresponds to a set of performance parameters of MEMS scanning mirrors 100.

[0143] The performance parameters of each MEMS scanning mirror 100 here may include scanning angle, stress and resonant frequency, or other performance parameters, and this application does not limit this.

[0144] Step S5: Evaluate multiple irregular geometric curves based on the evaluation function to obtain the target irregular geometric curve.

[0145] The performance parameters of the MEMS scanning mirror 100 corresponding to the target irregular geometric curve here are the target performance parameters.

[0146] The aforementioned target irregular geometric curve can be used to form the first elastic element 31 or the second elastic element 61, so that the MEMS scanning mirror 100 with the elastic element prepared according to the target irregular geometric curve can have the target performance parameters, namely, it can maintain a large scanning angle, low stress, high resonant frequency, etc.

[0147] For example, in simulation software, the scanning angle of the MEMS scanning mirror 100 with the first elastic element 31 prepared based on each irregular geometric curve in each axis is collected, as well as parameters such as stress and resonant frequency at the scanning angle. Then, the aforementioned parameters are used to evaluate the MEMS scanning mirror 100, that is, to evaluate the irregular geometric curve and determine the optimal irregular geometric curve.

[0148] For example, by using an evaluation function to evaluate multiple irregular geometric curves, the obtained evaluation scores can be sorted, and the irregular geometric curve corresponding to the highest evaluation score can be retained, i.e., the target irregular geometric curve.

[0149] For example, an evaluation function can be constructed based on the performance parameters of the MEMS scanning mirror 100 to comprehensively evaluate irregular geometric curves from multiple perspectives (such as scanning angle, stress, resonant frequency, etc.), thereby selecting the irregular geometric curve with the best overall performance, i.e. the target irregular geometric curve, thereby improving the dynamic response speed and stability of the MEMS scanning mirror 100, enabling it to be applied in applications with high requirements for scanning speed and accuracy.

[0150] The above average function can be: , Where Evaluate represents the evaluation score of the irregular geometric curve, α represents the trade-off coefficient between the maximum scanning angle and the resonant frequency, angle1 represents the maximum scanning angle of the MEMS scanning mirror 100 in the inner frame angle, and angle2 represents the maximum scanning angle of the scanning mirror 100 in the outer frame angle. This represents the resonant frequency corresponding to the scanning angle 1 of the MEMS scanning mirror 100. This represents the resonant frequency corresponding to the scanning angle 2 of the MEMS scanning mirror 100.

[0151] The inner frame here is the first sub-part 41, and the outer frame is the second sub-part 42.

[0152] Thus, by evaluating multiple irregular geometric curves using an evaluation function, a target irregular geometric curve is determined, and a first elastic element 31 or a second elastic element 61 is prepared based on this target irregular geometric curve. This increases the scanning angle of the MEMS scanning mirror 100 with the aforementioned first elastic element 31 or second elastic element 61, while also having a high resonant frequency. This improves the dynamic response speed and stability of the MEMS scanning mirror 100, enabling it to be used in applications with high requirements for scanning speed and accuracy, such as real-time detection by lidar and high frame rate optical imaging.

[0153] For example, the value of the trade-off coefficient α can be determined according to the application scenario of the MEMS scanning mirror 100. For instance, when the MEMS scanning mirror 100 is used in displays, LiDAR, etc., it is necessary to prioritize ensuring that the MEMS scanning mirror 100 has a large scanning angle. In this case, the value of the trade-off coefficient α is greater than 0.5. When the MEMS scanning mirror 100 is used in laser communication, high-speed scanning, etc., it is necessary to prioritize ensuring a high resonant frequency. In this case, the value of the trade-off coefficient α is less than 0.5. In applications where scanning angle and resonant frequency are equally important, the value of the trade-off coefficient α is equal to 0.5.

[0154] For example, the evaluation score of each irregular curve can be weighted and summed with the figure of merit (FOM) of the MEMS scanning mirror 100. The sum is the comprehensive evaluation score of the irregular geometric curve. The irregular geometric curve corresponding to the highest final evaluation score is used as the target regular geometric curve for actual production.

[0155] The MEMS scanning mirror 100 here has a first elastic element 31 fabricated based on an irregular geometric curve.

[0156] It is understood that in the embodiments of this application, the initial population is optimized by using a genetic algorithm and different strategies (such as using different crossover probabilities, mutation probabilities, etc.) at different stages to obtain multiple irregular geometric curves, i.e., the design profile of the elastic element. The optimal irregular geometric curve, i.e. the target irregular geometric curve, is selected from the aforementioned multiple irregular geometric curves by means of a rating function. When the elastic element (such as the first elastic element 31) prepared according to the target irregular geometric curve is applied to the MEMS scanning mirror 100, the MEMS scanning mirror 100 can maintain a large scanning angle while having low stress and high resonant frequency. This can improve the dynamic response speed and stability of the MEMS scanning mirror 100, making it applicable to applications with high requirements for scanning speed and accuracy.

[0157] Figure 13 This is a flowchart for obtaining an initial target irregular geometric curve, provided as an embodiment of this application.

[0158] In some embodiments, see Figure 13 Before performing step S5 in the above embodiments, the following step S50 is also included: Step S50: Based on the stress of the MEMS scanning mirror 100 corresponding to each irregular geometric curve and the preset stress, obtain the initial target irregular geometric curve.

[0159] That is, multiple irregular geometric curves can be initially screened from the perspective of stress.

[0160] For example, the stress of the MEMS scanning mirror 100 collected during the simulation is compared with the preset stress. If it is greater than the preset stress, the irregular geometric curve used in this simulation is retained, that is, the initial target irregular geometric curve; otherwise, the irregular geometric curve used in this simulation is discarded.

[0161] The preset stress here can be 1 GPa.

[0162] For example, after obtaining the first irregular geometric curve, an evaluation function can be used to evaluate the first irregular geometric curve to obtain the target irregular geometric curve.

[0163] In this way, by using preset stress to initially screen multiple irregular geometric curves, on the one hand, the number of subsequent evaluations of irregular geometric curves using evaluation functions can be reduced, thereby reducing the overall computational load; on the other hand, it can also ensure that the stress of the MEMS scanning mirror 100 with elastic components prepared according to the initial target irregular geometric curve is small (e.g., not exceeding 1 GPa), thereby ensuring that the MEMS scanning mirror 100 has a large scanning angle and high resonant frequency while reducing its stress, so as to improve the overall service life of the MEMS scanning mirror 100.

[0164] Figure 14 This is a schematic diagram of an irregular geometric curve provided in an embodiment of this application. Figure 15 To Figure 14 An enlarged view at point Q of the result obtained after smoothing the irregular geometric curve.

[0165] In some embodiments, see Figure 14 and Figure 15 Before performing parametric modeling and analysis based on multiple irregular geometric curves to obtain multiple sets of performance parameters of the MEMS scanning mirror 100, a smoothing algorithm can be used to smooth the aforementioned multiple irregular geometric curves to obtain a curve with continuous contour and gentle curvature change, namely the first irregular geometric curve.

[0166] For example, in simulation software, parametric curves, spline curves, etc., can be used to smooth irregular geometric curves or initial target irregular geometric curves to obtain smooth irregular geometric curves.

[0167] For example, after obtaining multiple first irregular geometric curves, an evaluation function can be used to evaluate the aforementioned multiple irregular geometric curves to obtain the target irregular geometric curve.

[0168] For example, in simulation software, the scanning angle of the MEMS scanning mirror 100 with the first elastic element 31 prepared based on each irregular geometric curve is collected at the inner frame angle and the outer frame angle, as well as the resonant frequency at the scanning angle. Then, the MEMS scanning mirror 100 is evaluated using the aforementioned parameters, that is, the first irregular geometric curve is evaluated, and the optimal irregular geometric curve is determined.

[0169] For example, by using an evaluation function to evaluate multiple first irregular geometric curves, and obtaining evaluation scores, the multiple evaluation scores can be sorted, and the irregular geometric curve corresponding to the highest evaluation score can be retained, i.e., the target irregular geometric curve.

[0170] In this way, smoothing irregular geometric curves can eliminate jagged edges and abrupt changes introduced by pixelation or discretization, making the geometric contour of the elastic component more continuous and smooth, avoiding the generation of stress concentration points, thereby improving the accuracy of simulation results and the feasibility of subsequent micro-nano fabrication processes.

[0171] It is understood that the aforementioned MEMS scanning mirror 100 can be a dual-axis scanning mirror, that is, it can rotate along two mutually perpendicular axes to achieve pitch or yaw scanning, and this application does not limit it in this respect.

[0172] The design process described above is explained below using the design of a single-axis MEMS scanning mirror 100 as an example.

[0173] Figure 16 A flowchart illustrating another design method for a MEMS scanning mirror provided in this application embodiment.

[0174] See Figure 16 The design method of the above-mentioned MEMS scanning mirror 100 includes the following steps L1 to L5: Step L1: Form the initial irregular geometric curve.

[0175] This forms the initial population, which consists of multiple irregular geometric curves. The specific formation process can be found in step S1, and will not be repeated here.

[0176] Step L2: Use a genetic algorithm to optimize the initial irregular geometric curve to obtain multiple irregular geometric curves.

[0177] For example, the entire optimization process can be divided into three stages, and different crossover and mutation probabilities can be used to optimize the initial population at different stages. The specific process can be found in the relevant content of steps S31 to S33, which will not be repeated here.

[0178] For example, software such as MATLAB and Python can be used to write script files to convert the elastic component model (i.e., irregular geometric curves) into DXF or CSV files, and then the aforementioned files can be sent into simulation software.

[0179] Step L3: Simulate and verify irregular geometric curves.

[0180] For example, after receiving a DXF or CSV file, the simulation software performs a simulation, that is, simulates the first elastic element 31, and sets the aforementioned first elastic element 31 in the target area P' so that the MEMS scanning mirror 100 works normally.

[0181] Step L4: Collect the performance parameters of the MEMS scanning mirror 100.

[0182] For example, during the normal operation of the MEMS scanning mirror 100, the maximum scanning angle of the MEMS scanning mirror 100, as well as the performance parameters such as stress and resonant frequency of the MEMS scanning mirror 100 while maintaining the maximum scanning angle, are collected using software such as MATLAB and Python. Based on the aforementioned performance parameters, the irregular geometric curve is evaluated using software such as MATLAB and Python in conjunction with the evaluation function to obtain an evaluation score.

[0183] Repeat steps L3 and L4 until all irregular geometric curves are simulated and evaluated, and an evaluation score is obtained.

[0184] For example, after acquiring the performance parameters of the MEMS scanning mirror 100, the aforementioned performance parameters can be stored for use when preparing the MEMS scanning mirror 100 later.

[0185] Step L5: Output the target irregular geometric curve.

[0186] For example, the irregular geometric curve with the highest evaluation score among multiple irregular geometric curves can be output as the target irregular geometric curve, and the corresponding performance parameters can be displayed.

[0187] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A MEMS scanning mirror, characterized in that, include: Reflector; Multiple first piezoelectric drive structures are disposed on opposite sides of the reflector along a first direction; In the plurality of first piezoelectric driving structures, some of the first piezoelectric driving structures located on the same side of the reflector are spaced apart along the second direction; both the first direction and the second direction are parallel to the reflector, and the first direction and the second direction intersect each other; Multiple sets of first elastic elements are provided, each set of first elastic elements being disposed between two adjacent first piezoelectric drive structures arranged along the second direction; each set of first elastic elements includes two first elastic elements, and the two first elastic elements are spaced apart along the second direction; each first piezoelectric drive structure is connected to the reflector through the first elastic element; Wherein, the shape of the orthographic projection of the first elastic element onto the reference plane is an irregular geometric curve; the reference plane is parallel to the reflector; the irregular geometric curve is... Where, I represents the irregular geometric curve, m represents the dimension of the first piezoelectric driving structure in the first direction, n represents half the dimension of the interval between two adjacent first piezoelectric driving structures located on the same side of the reflector in the second direction, and x represents... At any point in the region, C represents the centerline of the irregular geometric curve, and r represents half the distance between the two boundaries of the first elastic element in the first direction.

2. The MEMS scanning mirror according to claim 1, characterized in that, The distance between the two boundaries of the first elastic element in the first direction is 10µm to 30µm.

3. The MEMS scanning mirror according to claim 1, characterized in that, Also includes: A support frame is arranged around the reflector along its circumference and is spaced apart from the reflector; The plurality of first elastic elements are located between the support frame and the reflector; Multiple second piezoelectric drive structures are disposed on both sides of the support frame along the second direction; Among the plurality of second piezoelectric structures, some of the second piezoelectric driving structures located on the same side of the support frame are spaced apart along the first direction; Multiple sets of second elastic elements, each set of second elastic elements includes two second elastic elements, and the two second elastic elements are spaced apart along the first direction; each second piezoelectric drive structure is connected to the support frame through the second elastic element; The support frame includes two first sub-parts and two second sub-parts, with the first sub-parts extending along the first direction and the second sub-parts extending along the second direction; along the second direction, the side of the first sub-parts closest to the reflector is in contact with the first piezoelectric drive structure. Along the second direction, the second sub-part contacts the side of the second piezoelectric drive structure closest to the reflector.

4. The MEMS scanning mirror according to claim 3, characterized in that, The second elastic element has the same structure as the first elastic element.

5. A design method for a MEMS scanning mirror, characterized in that, The method is applied to the MEMS scanning mirror as described in any one of claims 1 to 4, wherein the method comprises: A target area is determined, and multiple center lines are generated within the target area based on a path planning algorithm; the target area is located between two adjacent piezoelectric drive structures. An initial population is formed based on a preset width and the multiple center lines; the initial population includes multiple initial irregular geometric curves; Based on a genetic algorithm, a phased strategy is used to process the initial population to obtain multiple irregular geometric curves; the processing includes crossover and mutation; the irregular geometric curves characterize the contour of the elastic element; Parametric modeling and analysis are performed based on the multiple irregular geometric curves to obtain multiple sets of performance parameters for MEMS scanning mirrors; the multiple irregular geometric curves correspond one-to-one with the performance parameters of the multiple sets of MEMS scanning mirrors; the performance parameters of each set of MEMS scanning mirrors include scanning angle, stress, and resonant frequency; The multiple irregular geometric curves are evaluated based on the evaluation function to obtain the target irregular geometric curve; the performance parameters of the MEMS scanning mirror corresponding to the target irregular geometric curve are the target performance parameters. Among them, the irregular geometric curve is Where I represents the irregular geometric curve, The target area is represented by x, any point within the target area is represented by C, the center line of the irregular geometric curve is represented by r, and half of the preset width is represented by r.

6. The design method of the MEMS scanning mirror according to claim 5, characterized in that, The initial population is processed using a phased strategy based on a genetic algorithm to obtain multiple irregular geometric curves, including: Based on the first crossover probability and the first mutation probability, the initial population is subjected to crossover and mutation processing to obtain multiple first individuals; Based on the second crossover probability and the second mutation probability, the plurality of first individuals are subjected to crossover and mutation processing to obtain a plurality of second individuals; Based on the third crossover probability and the third mutation probability, the multiple second bodies are subjected to crossover and mutation processing to obtain multiple irregular geometric curves. Wherein, the second crossover probability is greater than the first crossover probability and less than the third crossover probability; the second mutation probability is less than the first mutation probability and greater than the third mutation probability.

7. The design method of the MEMS scanning mirror according to claim 5, characterized in that, Also includes: An evaluation function is constructed based on the performance parameters of the MEMS scanning mirror; the evaluation function is: Wherein, Evaluate represents the evaluation score of the irregular geometric curve, α represents the trade-off coefficient between the maximum scanning angle and the resonant frequency, angle1 represents the maximum scanning angle of the MEMS scanning mirror at the inner frame angle, and angle2 represents the maximum scanning angle of the MEMS scanning mirror at the outer frame angle. This indicates the resonant frequency corresponding to the scanning angle 1 of the MEMS scanning mirror. This represents the resonant frequency corresponding to the scanning angle 2 of the MEMS scanning mirror.

8. The design method of the MEMS scanning mirror according to claim 5, characterized in that, Before evaluating the multiple irregular geometric curves based on the evaluation function to obtain the target irregular geometric curve, the process further includes: Based on the stress and preset stress of the MEMS scanning mirror corresponding to each irregular geometric curve, the initial target irregular geometric curve is obtained; The evaluation of the multiple irregular geometric curves based on the evaluation function to obtain the target irregular geometric curve includes: The initial target irregular geometric curve is evaluated based on the evaluation function to obtain the target irregular geometric curve.

9. The design method of the MEMS scanning mirror according to claim 5, characterized in that, Before performing parametric modeling and analysis based on the multiple irregular geometric curves to obtain multiple sets of performance parameters for the MEMS scanning mirror, the process also includes: The irregular geometric curve is smoothed using a smoothing algorithm to obtain a first irregular geometric curve; The parametric modeling and analysis based on the multiple irregular geometric curves yields multiple sets of performance parameters for the MEMS scanning mirror, including: Parametric modeling and analysis are performed based on multiple first irregular geometric curves to obtain multiple sets of performance parameters for MEMS scanning mirrors.

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