A high-bandwidth MEMS scanning mirror device and its design method

Abstract

The present invention provides a high-bandwidth MEMS scanning mirror device and a design method thereof, wherein the maximum driving torque τ of the high-bandwidth MEMS scanning mirror device and the maximum scanning angle θ of the micro-reflector are max , flexible torsion beam torsional stiffness K θ =τ / (θ max N 2 ), N is greater than 1; the feedback control chip receives the real-time torsion angle and target scanning angle sensed by the monolithic integrated angle sensor, processes it to adjust the closed-loop feedback drive signal, and controls the torsion of the micro-mirror through closed-loop feedback. The torsional stiffness of the flexible torsion beam in the present invention is 1 / N of the conventional torsional stiffness. 2 , combined with feedback control to improve the scanning working bandwidth of the scanning mirror device, and break the thinking inertia of MEMS scanning mirror to improve the bandwidth; at the same time, the torsional stiffness of the torsional beam of micro-mirrors of different sizes is different, which ensures the structural strength of the scanning mirror and optimizes the scanning working bandwidth; in addition, the PID algorithm feedback controls the torsion of the micro-mirror, which greatly improves the scanning working bandwidth.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor integrated circuit manufacturing and optical technology, and in particular relates to a high-bandwidth MEMS scanning mirror device and a design method thereof. Background Art

[0002] MEMS scanning mirrors are optical MEMS devices that integrate a micro-actuator and a micro-mirror on a single chip using MEMS technology. Due to their small size and light weight, they offer fast, high-precision dual-axis beam pointing and multi-axis scanning capabilities, making them important applications in modern optical technology. With the increasing application of optical MEMS technology, higher requirements are being placed on the scanning speed and operating bandwidth of MEMS scanning mirrors to accommodate various fast optical scanning applications. Among these applications, large-scale, high-bandwidth (approximately 0.5-2kHz) MEMS scanning mirrors are required for precision tracking MEMS fast-reflecting mirrors in space laser communication terminals, image stabilizers or laser pointing stabilizers for vehicle-mounted or airborne motion platforms, high-speed laser processing (cutting, drilling, welding, etc.), and high-speed 3D laser printing. Furthermore, small-scale, high-bandwidth (approximately 10-100kHz) MEMS scanning mirrors and their arrays are also required for applications such as MEMS high-speed (100kHz) optical phase shifter arrays, MEMS high-speed (microsecond) optical switches, and MEMS high-speed (microsecond) optical switch arrays.

[0003] The prevailing design philosophy in existing MEMS scanning mirror design is to maximize the operating modal frequency of the MEMS scanning mirror, as long as the driving force or torque permits, to achieve fast scanning characteristics and, in turn, maximize the scanning bandwidth. Because the electrostatic drive of the MEMS scanning mirror provides a unidirectional driving force or driving torque, the "electrostatic attraction" relies primarily on the rebound force of the flexible torsion beam when scanning in the reverse direction. Therefore, the industry has long held the design philosophy that "the higher the stiffness of the flexible torsion beam, the greater the rebound force, and the faster the MEMS scanning mirror."

[0004] However, due to the limitations of MEMS process parameters and the driving capacity of the driving electrical signal, the stiffness of the flexible torsion beam cannot continuously and linearly increase the working bandwidth of the MEMS scanning mirror, resulting in significant limitations on the improvement of the existing MEMS scanning mirror's scanning working bandwidth, which cannot meet the growing demand for high-bandwidth scanning applications.

[0005] Therefore, there is an urgent need to develop new MEMS scanning mirror device designs and drive control methods to meet the demand for higher bandwidth MEMS scanning mirrors in practical applications.

[0006] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of this application and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because these solutions are explained in the background technology part of this application. Summary of the Invention

[0007] In view of the above shortcomings of the prior art, an object of the present invention is to provide a high-bandwidth MEMS scanning mirror device and a design method thereof, so as to solve the problem that the bandwidth improvement of the MEMS scanning mirror device in the prior art is limited.

[0008] To achieve the above-mentioned object, the present invention provides a high-bandwidth MEMS scanning mirror device, which includes: a high-bandwidth MEMS scanning mirror chip, a power driver chip, an angle sensing detection circuit chip, a feedback control chip, and an input / output connector;

[0009] The high-bandwidth MEMS scanning mirror chip includes a flexible torsion beam, a micro-mirror, a substrate, a drive structure, and an angle sensing detection structure. The micro-mirror and the substrate are torsionally connected via the flexible torsion beam. The drive structure controls the micro-mirror to perform torsional motion relative to the substrate. The angle sensing detection structure is used to detect the real-time torsion angle of the micro-mirror. The maximum torque that the drive structure can provide to the micro-mirror is τ, and the maximum scanning angle of the micro-mirror is θ. max When the torsional stiffness K of the flexible torsion beam is θ =τ / (θ max N 2 ), N is a number greater than 1;

[0010] The power driver chip is electrically connected to the driving structure to control the driving state of the micro-mirror by the driving structure; the angle sensing detection circuit chip is electrically connected to the angle sensing detection structure to receive and process the real-time torsion angle of the micro-mirror detected by the angle sensing detection structure to obtain a real-time angle signal; the input / output connector is electrically connected to the external control system to receive the target angle signal input by the external control system; the feedback control chip is electrically connected to the angle sensing detection circuit chip, the power driver chip, and the input / output connector to receive the real-time angle signal calculated by the angle sensing detection circuit chip and the target angle signal received by the input / output connector, and obtains an adjusted closed-loop feedback driving signal through a preset high-bandwidth feedback control algorithm, and transmits the adjusted closed-loop feedback driving signal to the power driver chip, and controls the driving state of the micro-mirror driven by the driving structure through the power driver chip, and the power driver chip controls the driving structure to drive the micro-mirror to twist in both directions.

[0011] Optionally, the high-bandwidth MEMS scanning mirror chip includes M micro-mirrors arranged in an array, each of the micro-mirrors has a corresponding flexible torsion beam, a driving structure and an angle sensing detection structure, the M micro-mirrors are on the same substrate, and M is an integer greater than or equal to 1.

[0012] Optionally, the preset high-bandwidth feedback control algorithm adopted by the feedback control chip is a PID algorithm, and the real-time angle signal and the target angle signal are processed by the PID algorithm to generate an adjustment closed-loop feedback drive signal.

[0013] Optionally, N is greater than or equal to 1.1 and less than or equal to 20.

[0014] Optionally, the mirror diameter of the micro-reflector is 0.2 mm-1 mm, the mirror thickness of the micro-reflector is 5 μm-50 μm, and N is greater than or equal to 5 and less than or equal to 20.

[0015] Optionally, the high-bandwidth MEMS scanning mirror device is one of a MEMS high-speed optical phase shifter array, a MEMS microsecond high-speed optical switch, or a MEMS microsecond high-speed optical switch array.

[0016] Optionally, the mirror diameter of the micro-reflector is 3 mm-20 mm, the mirror thickness of the micro-reflector is 50 μm-500 μm, and N is less than 5.

[0017] Optionally, the high-bandwidth MEMS scanning mirror device is one of a MEMS fast reflection mirror, an image stabilizer, a laser pointing stabilizer, a high-speed laser processing device or a high-speed 3D laser printing device.

[0018] Optionally, the mirror diameter of the micro-reflector is 1 mm-3 mm, the mirror thickness of the micro-reflector is 20 μm-200 μm, and N is greater than or equal to 4 and less than or equal to 15.

[0019] The present invention also provides a design method for a high-bandwidth MEMS scanning mirror device, the design method being used to design any of the high-bandwidth MEMS scanning mirror devices described above, the design method comprising:

[0020] According to the driving structure and driving voltage of the high-bandwidth MEMS scanning mirror device, the maximum torque that the high-bandwidth MEMS scanning mirror device can provide to the micro-reflector is calculated by simulation tools as τ, and the design target of the maximum scanning angle of the micro-reflector of the high-bandwidth MEMS scanning mirror device is θ max ;

[0021] Calculate the torsional stiffness K of the flexible torsion beam of the high-bandwidth MEMS scanning mirror device θ =τ / (θmax N 2 ), N is a number greater than 1; the torsional stiffness is K θ1 The flexible torsion beam serves as a torsional connection between the micro-mirror and the substrate of the high-bandwidth MEMS scanning mirror device.

[0022] As described above, the high-bandwidth MEMS scanning mirror device and the design method thereof of the present invention have the following beneficial effects:

[0023] The present invention sets the torsional stiffness of the flexible torsion beam to be the conventional torsional stiffness τ / θ max 1 / N 2 , reducing the torsional stiffness of the flexible torsion beam to increase the acceleration of the micro-mirror during torsional acceleration, cooperating with the feedback control chip on the torsional motion state to increase the acceleration of the micro-mirror during torsional deceleration, and avoiding overshoot caused by excessive torsional amplitude of the scanning mirror, thereby greatly improving the working bandwidth that the scanning mirror device can achieve;

[0024] The present invention uses different degrees of torsional stiffness reduction for micro-mirrors of different sizes to ensure the structural strength of the micro-mirrors while optimizing the working bandwidth.

[0025] The present invention utilizes PID algorithm to perform torsional feedback control of the micro-mirror, thereby further improving the achievable working bandwidth;

[0026] The present invention reduces the torsional stiffness of the torsion beam rather than increasing it in a conventional manner, and improves the working bandwidth in conjunction with feedback control, thereby breaking the conventional design thinking of increasing the bandwidth of MEMS scanning mirror devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Shown is a top view structural schematic diagram of the basic structure of the high-bandwidth MEMS scanning mirror chip in Example 1 of the present invention.

[0028] Figure 2 Shown is a side view structural schematic diagram of the high-bandwidth MEMS scanning mirror chip in Example 1 of the present invention.

[0029] Figure 3 Shown is a side view structural schematic diagram of the high-bandwidth MEMS scanning mirror chip in Example 1 of the present invention.

[0030] Figure 4 Shown is a schematic side view of the structure of the high-bandwidth MEMS scanning mirror device in the package of the example of embodiment 1 of the present invention.

[0031] Figure 5 Shown is a schematic diagram of the horizontal cross-sectional structure of the electrodes and leads of the high-bandwidth MEMS scanning mirror chip in Example 4 of the present invention.

[0032] Component number description

[0033] 100. High-bandwidth MEMS scanning mirror chip; 111. Inner axis torsion beam; 112. Outer axis torsion beam; 113. Motion frame; 114. Flexible support microstructure / buffered flexible support beam; 115. Buffer support frame; 120. Micromirror; 121. Optical high-reflection film; 130. Substrate; 131. Bonding layer; 132. Insulating oxide layer; 133. Electrode pad; 134. Peripheral substrate; 140. Driving structure; 141. Driving electrode; 142. Driving electrode lead; 143. Linear insulating groove; 150. Angle sensing detection structure; 151. Sensing electrode; 152. Sensing electrode lead; 153. Circular insulating groove; 161. Scanning inner axis; 162. Scanning outer axis; 170. Air gap;

[0034] 210, power driver chip; 220, angle sensor detection circuit chip; 230, feedback control chip;

[0035] 300. High-bandwidth MEMS scanning mirror device; 310. Input / output connector; 320. PCB board; 321. Bonding wire; 330. Flexible flat cable; 340. Package shell; 341. Optical window; 342. Incident light beam; 343. Outgoing light beam. DETAILED DESCRIPTION

[0036] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0037] For example, when describing the embodiments of the present invention, schematic diagrams illustrating device structures may be partially enlarged for ease of explanation. These schematic diagrams are merely illustrative and should not limit the scope of the present invention. Furthermore, in actual production, three-dimensional dimensions, including length, width, and depth, should be included.

[0038] For convenience of description, spatially relative terms such as "under," "below," "below," "below," "above," and "upper" may be used herein to describe the relationship of one element or feature to other elements or features shown in the drawings. It will be understood that these spatially relative terms are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the drawings.

[0039] In the context of the present application, a structure described as a first feature being "above" a second feature may include embodiments where the first and second features are in direct contact, and may also include embodiments where additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0040] It should be noted that the illustrations provided in this embodiment are only used to schematically illustrate the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0041] Example 1:

[0042] This embodiment provides a high-bandwidth MEMS scanning mirror device 300, such as Figure 1-Figure 4 As shown, the high-bandwidth MEMS scanning mirror device 300 includes: a high-bandwidth MEMS scanning mirror chip 100, a power driver chip 210, an angle sensing detection circuit chip 220, a feedback control chip 230 and an input / output connector 310;

[0043] like Figure 1-Figure 3 As shown, the high-bandwidth MEMS scanning mirror chip 100 includes a flexible torsion beam, a micro-mirror 120, a substrate 130, a driving structure 140, and an angle sensing detection structure 150. The micro-mirror 120 and the substrate 130 are torsionally connected via the flexible torsion beam. The driving structure 140 controls the micro-mirror 120 to perform torsional motion relative to the substrate 130. The angle sensing detection structure 150 is used to detect the real-time torsion angle of the micro-mirror 120. The maximum torque that the driving structure 140 can provide to the micro-mirror 120 is τ, and the maximum scanning angle of the micro-mirror 120 is θ. max When the torsional stiffness K of the flexible torsion beam is θ =τ / (θ max N 2 ), N is a number greater than 1;

[0044] The power driver chip 210 is electrically connected to the drive structure 140 to control the driving state of the micro-mirror 120 by the drive structure 140; the angle sensing detection circuit chip 220 is electrically connected to the angle sensing detection structure 150 to receive and process the real-time torsion angle of the micro-mirror 120 detected by the angle sensing detection structure 150 to obtain a real-time angle signal; the input / output connector 310 is electrically connected to the external control system to receive the target angle signal input by the external control system; the feedback control chip 230 is electrically connected to the angle sensing detection circuit chip 220 and the power driver chip 140 to control the driving state of the micro-mirror 120 by the drive structure 140; the angle sensing detection circuit chip 220 is electrically connected to the angle sensing detection circuit chip 150 to receive and process the real-time torsion angle of the micro-mirror 120 detected by the angle sensing detection structure 150 to obtain a real-time angle signal; the input / output connector 310 is electrically connected to the external control system to receive the target angle signal input by the external control system; the feedback control chip 230 is electrically connected to the angle sensing detection circuit chip 220 and the power driver chip 140 to control the driving state of the micro-mirror 120 by the angle sensing detection circuit chip 150 The dynamic chip 210 and the input / output connector 310 are electrically connected to receive the real-time angle signal calculated by the angle sensing detection circuit chip 220 and the target angle signal received by the input / output connector 310, and obtain an adjustment closed-loop feedback drive signal through a preset high-bandwidth feedback control algorithm, and transmit the adjustment closed-loop feedback drive signal to the power driver chip 210. The power driver chip 210 controls the driving state of the drive structure 140 to drive the micro-mirror 120, and the power driver chip 210 controls the drive structure 140 to drive the micro-mirror 120 to twist bidirectionally.

[0045] In the prior art, unlike conventional electromechanically driven mechanical structures, MEMS scanning mirrors, which primarily control deceleration and acceleration via electromagnetic actuators, are decelerated by the resistance of a flexible torsion beam's significant torsional rebound force. Open-loop scanning control is employed. Consequently, MEMS scanning mirrors primarily focus on increasing the torsional rebound force to improve deceleration and acceleration, rather than reducing it to increase scanning speed. Therefore, the prevailing design philosophy in MEMS scanning mirror design (referred to as "conventional design technology") is to maximize the MEMS scanning mirror's scanning modal eigenfrequency f, within the constraints of the MEMS chip design, to achieve fast scanning characteristics and, consequently, maximize the scanning bandwidth. This design philosophy stems from the unidirectional driving force or torque of the MEMS scanning mirror's electrostatic drive, the "electrostatic attraction." Scanning in the reverse direction primarily relies on the rebound force of the flexible torsion beam. Consequently, the industry has long held the belief that "the higher the stiffness of the flexible torsion beam, the greater its rebound force, and the faster the MEMS scanning mirror." The design idea is to set the maximum scanning angle of the MEMS scanning mirror chip according to the design target θ when the driving force or torque is allowed. max , to increase the scanning modal frequency of the MEMS scanning mirror as much as possible. Under the guidance of this design concept, the specific steps of the "common design technology" of the MEMS scanning mirror are as follows:

[0046] 1) Based on the chip size, microstructure process parameters (limited by existing MEMS processing technology), drive mode and drive signal size of the MEMS scanning mirror, the maximum drive torque τ of the MEMS driver can be calculated and simulated. max ;

[0047] 2) According to the angular scanning range of the MEMS scanning mirror (-θ max to +θ max ) indicator requirements, under the guidance of the design idea of ​​"maximizing the scanning working mode eigenfrequency of the MEMS scanning mirror", the torsional stiffness of the flexible torsion beam of the MEMS scanning mirror is maximized in the design, and the design torsional stiffness K is obtained. θ =τ max / θ max ;

[0048] 3) According to formula f 寻常 =(2π) -1 (K θ / I) 1 / 2 , get the working mode eigenfrequency f of the MEMS scanning mirror 寻常 , where I is the moment of inertia of the MEMS scanning mirror around the scanning axis;

[0049] 4) Through the microstructure air damping design, the motion damping coefficient of the MEMS scanning mirror is controlled to be close to the proximity damping. Under the drive of the step drive signal, the working bandwidth of the open-loop control is only the working mode eigenfrequency f 寻常 The maximum operating bandwidth of the closed-loop control is about 50-70% of the working mode eigenfrequency f in the ordinary design. 寻常 4 times.

[0050] Due to the limitations of MEMS process parameters and the size of the driving electrical signal, this design method cannot continuously improve the scanning working bandwidth of the MEMS scanning mirror by continuously increasing the torsional stiffness of the flexible torsion beam. At the same time, the increase in torsional stiffness will also require a higher driving voltage to achieve the driving acceleration during initial acceleration, and the increase in driving voltage is limited, which limits the driving acceleration during initial acceleration, resulting in a limited improvement in the overall scanning working bandwidth. Reducing the stiffness of the flexible torsion beam will lead to a decrease in the rebound force of the flexible torsion beam, reducing the acceleration of the MEMS scanning mirror during torsional deceleration, thereby reducing the working bandwidth. Although closed-loop feedback control can also be used to increase the working bandwidth, it is limited by the current structure of continuously increasing the torsional stiffness of the flexible torsion beam in order to increase the working bandwidth, which limits the driving acceleration during initial acceleration. The scanning working bandwidth of the current closed-loop feedback control can only reach the corresponding scanning mode eigenresonance frequency f at most. 寻常Even though the bandwidth is 4 times that of the original, it still cannot meet the growing application demand for high-bandwidth MEMS scanning mirrors. For example, the precision tracking MEMS fast-reflecting mirrors of space laser communication terminals, image stabilizers and laser pointing stabilizers for vehicle-mounted or airborne motion platforms, as well as high-speed laser processing (cutting, punching, welding, etc.), high-speed 3D laser printing equipment and other applications require large-size mirrors (3mm-20mm in diameter) and high-bandwidth MEMS scanning mirrors, and the bandwidth needs to be around 0.5-2kHz; or MEMS high-speed (100kHz) optical phase shifter arrays, MEMS high-speed (microsecond) optical switches, MEMS high-speed (microsecond) optical switch arrays and other applications require small-size mirrors (0.2mm-1.0mm in diameter) and high-bandwidth MEMS scanning mirrors and their arrays, and the bandwidth needs to be between 10-100kHz. z; using the aforementioned common design technology to obtain a large-scale MEMS scanning mirror with a mirror diameter of 10 mm, the scanning angle range is ±0.3°, the eigenfrequency of its scanning mode is around 150 Hz, the open-loop control scanning working bandwidth is only 100 Hz, and the closed-loop control working bandwidth can reach up to 600 Hz, which cannot meet the requirements of MEMS fast-reflection mirrors; and for small-scale MEMS scanning mirrors with a mirror diameter of 0.2 mm to 1 mm, the scanning working mode frequency is around 1-2 kHz, the open-loop control working bandwidth is 500-1000 Hz, and the closed-loop control working bandwidth is 4-8 kHz, which is also difficult to meet the working bandwidth requirements of high-speed MEMS optical switching with microsecond switching time.

[0051] Therefore, at present, my country's space laser communication systems use a large number of electromechanical fast-reflecting mirrors imported from abroad using traditional technology. They use piezoelectric ceramics or voice coil motors as scanning drivers, eddy current sensors as scanning angle sensors, and metal flexible mechanisms or bearings as dual-axis motion mechanisms. They are assembled manually using a large number of components. They are large in size, heavy in weight, high in cost, and have high driving power consumption. This has become one of the important reasons for the high cost of commercial aerospace satellite laser communication terminal systems. The use of MEMS process technology to mass-produce MEMS fast-reflecting mirrors at low cost is of great significance to the development of a new generation of lightweight, low-cost satellite laser communication systems required for my country's commercial aerospace.

[0052] The present invention reduces the torsional stiffness of the flexible torsion beam to the torsional stiffness K in the "conventional design technology". θ(寻常) 1 / N 2 , without increasing the torsional stiffness of the flexible torsion beam, contrary to the “conventional design technology”, the torsional stiffness of the flexible torsion beam is reduced, so that the operating modal frequency f of the high-bandwidth MEMS scanning mirror device 300 is reduced to the conventional design operating modal frequency f 寻常1 / N times; by reducing torsional stiffness and reducing rebound resistance, the acceleration of the flexible torsion beam during the initial accelerated torsion process is increased to achieve rapid scanning. At the same time, the design of the feedback control chip 230 continuously adjusts the driving state of the flexible torsion beam through feedback, and controls the acceleration of the flexible torsion beam during deceleration to remain within the required range, thereby avoiding torsional overshoot of the torsion beam. At the same time, a MEMS scanning mirror device with higher bandwidth (faster response speed) than the existing technology can be achieved under the same driving voltage, thereby being able to adapt to the high requirements of the rapidly developing MEMS scanning mirror device for scanning working bandwidth. Under the same design constraints, the scanning working bandwidth BW can reach the scanning working bandwidth BW of the existing MEMS scanning mirror chip design. 寻常 N times (N is greater than 1), which is conducive to the technological application breakthrough of MEMS scanning mirrors in various key fields, effectively improving the production efficiency and parameter performance of traditional high-cost fast-reflection mirrors and other equipment, and has broad application prospects.

[0053] Specifically, the real-time angle signal and the target angle signal may be angle values ​​or curves showing angle changes over time, and may be set as required.

[0054] Specifically, the feedback control bandwidth of the preset high-bandwidth feedback control algorithm is at least twice the designed working bandwidth BW of the high-bandwidth MEMS scanning mirror device 300, and the feedback control bandwidth can be as high as 5 to 15 times the working bandwidth BW of the MEMS scanning mirror chip; the signal output bandwidth of the angle sensing detection structure 150 is 5 to 15 times the designed working bandwidth BW of the high-bandwidth MEMS scanning mirror device 300; the scanning working bandwidth BW of the high-bandwidth MEMS scanning mirror chip 100 is greater than or equal to the natural resonant frequency f of the working mode of the MEMS scanning mirror chip in the conventional design 寻常 4N times (20≥N≥1.1), that is, BW≥N×BW 寻常 , so that the scanning bandwidth BW of the high-bandwidth MEMS scanning mirror chip 100 can be as high as f 寻常 4.4 to 80 times, which is much larger than the maximum f that can be achieved by closed-loop feedback control in ordinary designs. 寻常 4 times the working bandwidth BW 寻常 .

[0055] Specifically, taking a MEMS scanning mirror with a scanning working bandwidth BW of 2300 Hz as an example, the driving control method of the high-bandwidth MEMS scanning mirror device 300 is as follows:

[0056] First, step 1 is performed, where the angle sensing detection circuit chip 220 of the high-bandwidth MEMS scanning mirror device 300 detects and obtains the torsion angle of the micro-mirror 120 of the high-bandwidth MEMS scanning mirror device 300 .

[0057] Specifically, the torsion angle detected by the angle sensing circuit chip 220 is transmitted through an angle signal, and the frequency of the angle signal must reach 11500Hz-23000Hz to ensure the feedback speed of the angle signal and achieve the goal of increasing the working bandwidth of the high-bandwidth MEMS scanning mirror device 300 to a preset level.

[0058] Then, step 2 is performed, the feedback control chip 230 receives the real-time angle signal obtained by the angle sensing detection circuit chip 220 and the target angle signal received by the input / output connector 310, and calculates the driving state required by the micro-mirror 120 through the obtained torsion angle according to the preset high-bandwidth feedback control algorithm, and obtains an adjusted closed-loop feedback driving signal.

[0059] Finally, step 3 is performed, the feedback control chip 230 transmits the obtained adjustment closed-loop feedback drive signal to the power drive chip 210 of the high-bandwidth MEMS scanning mirror device 300, and the power drive chip 210 adjusts the drive state of the micro-mirror 120 according to the obtained adjustment closed-loop feedback drive signal, and returns to step 1.

[0060] In one embodiment, the feedback control chip 230 uses a PID algorithm to adjust the calculation feedback of the closed-loop feedback drive signal. The feedback bandwidth of the feedback control chip 230 using the PID algorithm reaches 11500Hz-23000Hz. The frequency of the drive control signal transmitted by the power driver chip 210 to the drive structure 140 to drive the micro-mirror 120 to a driving state must reach 11500Hz-23000Hz to ensure the speed of feedback control and drive, thereby achieving the goal of increasing the working bandwidth of the high-bandwidth MEMS scanning mirror device 300 to a preset level.

[0061] Specifically, the PID algorithm feedback bandwidth is related to the control accuracy of the scanning angle. A larger PID feedback bandwidth results in higher scanning angle accuracy. A PID feedback bandwidth that is 5-10 times the scanning operating bandwidth of the high-bandwidth MEMS scanning mirror device 300 can ensure sufficient scanning accuracy. It should be noted that the PID feedback bandwidth requires fast response support from the feedback control chip 230, the angle sensing circuit chip 220, and the power driver chip 210. When selecting these chips, select those that meet the technical requirements. This is easily achieved with existing chip technology.

[0062] To optimize the drive scheme, the drive structure 140 of the high-bandwidth MEMS scanning mirror device 300 used in this embodiment is a MEMS electrostatic torsional actuator, which is required to provide bidirectional torsional drive with high angular acceleration. This means that clockwise or counterclockwise scanning can be achieved according to the control system's requirements. In other words, accelerated or decelerated angular scanning can be achieved according to the feedback control chip 230's requirements. Due to the inherent characteristics of electrostatic torsional actuators, they can only provide electrostatic attraction, but not electrostatic repulsion. In other words, electrostatic torsional actuators can only provide driving torque in a single torsional direction. A pair of electrostatic torsional actuators, arranged symmetrically with flexible torsion beams, form a differential drive structure. At a given moment, the driving torque of one electrostatic torsional actuator is greater than that of the other. This torque difference provides the driving torque of the MEMS scanning mirror. Bidirectional torsional drive is achieved through electrical signal control of the differential drive structure.

[0063] Therefore, in this embodiment, by simultaneously applying a 100V DC bias voltage to a pair of differential electrostatic torsion actuators, the electrostatic torque of the DC bias voltage is balanced when the scanning angle is 0 rad. When positive and negative polarity precision-programmed voltage signals are applied to the bilaterally symmetrical differential electrostatic torsion actuators, a torque approximately twice that of a single electrostatic torsion actuator can be achieved, with the torsion direction being toward the electrode applying the positive voltage. When the polarity of the precision-programmed voltage signals applied to the two symmetrical differential electrostatic torsion actuators is opposite, the torsion direction is opposite. Thus, by controlling the polarity of the precision-programmed voltage signals, electrostatic bidirectional torsion drive can be achieved, and the driving torque can be even greater. To achieve high-speed scanning drive, a high angular acceleration value (including angular acceleration values ​​for acceleration or deceleration) is a prerequisite, and bidirectional torsion drive can provide high angular acceleration to achieve acceleration or deceleration. It should be noted that in high-speed scanning drive, deceleration and acceleration play equally important roles in ensuring scanning angle accuracy and preventing scanning overshoot.

[0064] Specifically, assuming that the control system requires the MEMS scanning mirror chip to quickly scan from 0 rad to an angle θ, the electrostatic torsional driving torque τ provided in the control scheme in the conventional design is θ(寻常) As the MEMS scanning mirror scans the inner axis scanning angle θ from the angle position 0rad to a certain intermediate angle position θ1, the rebound torque of the inner axis flexible torsion beam is K θ(寻常)θ1. During the scanning process, the rebound torque continuously increases, and the scanning angular acceleration gradually decreases to 0. Without considering overshoot (achieved by PID algorithm control feedback), the fastest scanning time is 1 / (4f), where f is the scanning modal frequency of the high-bandwidth MEMS scanning mirror chip 100. In this embodiment, the MEMS scanning mirror device in the prior art, which is identical except for the torsional stiffness and drive method of the flexible torsion beam, has the fastest scanning time from angular position 0 rad to angular position θ of 0.87 ms, and the scanning bandwidth of the MEMS scanning mirror is 4f.

[0065] As a comparison between the optimized design of this embodiment and the conventional design, assuming that the control system requires the inner axis of the scanning mirror to quickly scan from 0 rad to θ, the torsional stiffness K of the flexible torsion beam provided by the optimized design of this embodiment is θ =K θ(寻常) / N 2 , under the condition of the same driving voltage, the electrostatic driving torque remains unchanged, that is, τ=τ 寻常 , the electrostatic torsional driving torque provided by the optimized design of this embodiment is:

[0066] τ=N 2 K θ θ; (1)

[0067] In this embodiment, N=2, so:

[0068] τ=4K θ θ; (2)

[0069] =3 K θ θ+K θ θ (3)

[0070] The second term K in the above formula (3) θ θ provides both angular acceleration and rebound torque of the inner shaft flexible torsion beam corresponding to the balance angle θ. The first item is 3K θ θ can be used to provide angular acceleration to reach the scanning angle, and the torsional moment continuously provides angular acceleration to reach the scanning angle before the scanning angle reaches θ.

[0071] As the scanning angular position variable of the inner axis of the scanning mirror is scanned from the angular position 0 rad to the angular position θ, when only the driving torque of the second term in equation (3) is considered, the resistance torque caused by the rebound torque of the inner axis flexible torsion beam gradually increases during the scanning process, and the scanning angular acceleration gradually decreases to 0. Without considering overshoot (using PID feedback control), the fastest scanning time is 1 / (4f). In this embodiment, the fastest scanning from the angular position 0 rad to the angular position θ is 1.74 ms, so the scanning bandwidth of the MEMS scanning mirror is 4f.

[0072] When the driving torque of the first term in (3) is considered at the same time, 3K θ θ is the driving torque that generates the scanning angular acceleration, and the angular acceleration value generated is 5000 rad / s 2 The acceleration value is at least greater than the driving torque K of the second term in formula (3) that needs to overcome the rebound torque of the flexible torsion beam. θ The angular acceleration generated by θ is three times the value, so the total angular acceleration generated by formula (3) is the driving torque K required to overcome the rebound torque of the flexible torsion beam. θ The angular acceleration generated by θ is more than 4 times the value, so the scanning time is <1 / (4×4f), that is, the scanning bandwidth BW of the high-bandwidth MEMS scanning mirror is greater than 16f, because f=f 寻常 / N, when N=2, 16f=8f 寻常 , and the scanning bandwidth BW of the MEMS scanning mirror device in the prior art is 寻常 4f 寻常 That is to say, the optimized design scheme is combined with the optimized driving scheme, and the scanning bandwidth BW of the MEMS scanning mirror is relatively large compared with the BW of the existing technology. 寻常 At least 2 times higher.

[0073] In one embodiment, the high-bandwidth MEMS scanning mirror chip 100 includes M micro-mirrors 120 arranged in an array, each of the micro-mirrors 120 has a corresponding flexible torsion beam, a driving structure 140 and an angle sensing detection structure 150, and the M micro-mirrors 120 are on the same substrate 130, where M is an integer greater than or equal to 1.

[0074] In one embodiment, the array of the M micro-reflectors 120 is a linear array or a square array, and may also be arranged in other arrays as needed.

[0075] In one embodiment, the high bandwidth MEMS scanning mirror device 300 is a dual-axis scanning mirror device, such as Figure 4As shown, the package of the high-bandwidth MEMS scanning mirror device 300 also includes an input / output connector 310, a PCB board 320 (Printed Circuit Board), a flexible cable 330, and a package shell 340 with a light window 341; the high-bandwidth MEMS scanning mirror chip 100, the power driver chip 210, the angle sensor detection circuit chip 220, the feedback control chip 230, and the input / output connector 310 are packaged on the PCB board 320, and the PCB board 320 is fixed on the package shell 340 with the light window 341. The mirror surface of the micro-mirror 120 of the MEMS scanning mirror chip faces the light window 341, and the incident light beam 342 enters the micro-mirror 120 through the light window 341, and the reflected light beam 343 is emitted from the micro-mirror 120 through the light window 341; the high-bandwidth MEMS scanning mirror chip 100 is manufactured using a MEMS bulk silicon process; The wide MEMS scanning mirror chip 100 includes a flexible torsion beam, a micro-mirror 120, a motion frame 113, a driving structure 140, an angle sensing detection structure 150, an electrode pad 133 (pad) and a substrate 130; the driving structure 140, under the action of a driving electrical signal provided by a power driver chip 210, bidirectionally drives the micro-mirror 120 to twist around a torsion axis within the plane of the high-bandwidth MEMS scanning mirror chip 100; the bidirectional drive refers to: a clockwise and counterclockwise bidirectional high angular acceleration torsion drive that can be controlled by a computer; the high-bandwidth MEMS scanning mirror chip 100 includes two mutually perpendicular horizontal scanning axes (external axes) and a vertical scanning axis (inner axis) on the mirror surface of the micro-mirror 120 as torsion axes.

[0076] In one embodiment, the high-bandwidth MEMS scanning mirror chip 100 is fixed to the front surface of the PCB board 320 using thermal conductive adhesive, and a gold wire is used as the bonding wire 321 through a wire bonding process to achieve an electrical connection between the high-bandwidth MEMS scanning mirror chip 100 and the PCB board 320.

[0077] In one embodiment, the power driver chip 210, the angle sensor detection circuit chip 220, the feedback control chip 230, and the input / output connector 310 are packaged on the back of the PCB board 320 through a flip-chip soldering process, and the flexible cable 330 is led out from the input / output connector 310 to form a "MEMS scanning mirror PCB board package."

[0078] In one embodiment, the power driver chip 210 , the angle sensing detection circuit chip 220 , and the feedback control chip 230 may be further integrated into an application-specific integrated circuit (ASIC) to improve circuit integration, reduce size, and lower costs.

[0079] In one embodiment, the PCB board 320 of the high-bandwidth MEMS scanning mirror device 300 is encapsulated and installed in a housing 340. The PCB board 320 is secured to the bottom of the housing 340 using thermally conductive adhesive, and the flexible flat cable 330 is extended through a side opening of the housing 340. The housing 340 is made of an aluminum alloy with excellent thermal conductivity. Screw holes are provided in the housing 340 for mechanical connection to the rear optical path platform of the satellite laser communication terminal. The housing 340 is capped with an optical window 341, which is made of glass with a high thermal expansion coefficient and has an anti-reflection coating at the operating wavelength applied to both surfaces.

[0080] In one embodiment, the MEMS driving mode of the driving structure 140 is any one of electrostatic driving, electromagnetic driving and piezoelectric driving, or any combination of two.

[0081] In one embodiment, the driving method of the driving structure 140 is electrostatic driving, and the driving structure 140 is one or both of an electrostatic flat plate driver and an electrostatic vertical comb driver;

[0082] The electrostatic flat plate driver is composed of a micro-mirror 120 (as an electrode) and a bottom plane electrode located on the surface of a substrate 130, with a gap of several microns to tens of microns between the micro-mirror 120 and the bottom plane electrode.

[0083] When the electrostatic flat-plate driver is a dual-axis driver, the bottom plane electrode includes four electrically isolated plane electrodes symmetrically distributed about two torsion axes and having the same shape, and the shape of the plane electrodes is a cone, an isosceles trapezoid or an isosceles triangle;

[0084] The electrostatic vertical comb teeth driver is composed of dynamic comb teeth and fixed comb teeth. The dynamic comb teeth and the fixed comb teeth are arranged alternately at equal intervals. There is a height difference between the dynamic comb teeth and the fixed comb teeth. The dynamic comb teeth and the fixed comb teeth are arranged symmetrically on both sides of the scanning axis.

[0085] In one embodiment, the motion mode of the micro-mirror 120 of the high-bandwidth MEMS scanning mirror chip 100 is quasi-static scanning, realizing vector scanning (ie, scanning in a specific time sequence and a specified scanning path).

[0086] In one embodiment, Figure 1As shown, the high-bandwidth MEMS scanning mirror chip 100 has a frame motion structure, that is, a universal joint structure including a motion frame 113 between the micro-mirror 120 and the substrate 130. The flexible torsion beam is divided into an inner-axis torsion beam 111 and an outer-axis torsion beam 112, which are perpendicular to each other within the plane of the high-bandwidth MEMS scanning mirror chip 100. There are two inner-axis torsion beams 111 connecting the micro-mirror 120 to the motion frame 113; there are two outer-axis torsion beams 112 connecting the motion frame 113 to the substrate 130 outside the motion frame 113. Due to the presence of the motion frame 113, the inter-axis coupling of the two axes is very small, and the torsion angle of the micro-mirror 120 along the other torsion axis is slightly affected when torsion is performed along one torsion axis. Specifically, the high-bandwidth MEMS scanning mirror chip 100 is a dual-axis MEMS scanning mirror.

[0087] In one embodiment, Figure 1 As shown, a mirror dynamic deformation buffer structure is also provided between the inner shaft torsion beam 111 and the micro-reflector 120. The mirror dynamic deformation buffer structure includes a flexible support microstructure 114 and a buffer flexible support beam 115. The flexible support microstructure 114 includes an even number of buffer flexible support beams 114, which are symmetrically arranged with the scanning inner axis 161 and the scanning outer axis 162 as symmetry axes; one end of the flexible support microstructure 114 supports the micro-reflector 120, and the other end thereof is connected to the buffer flexible support beam 115, and at the same time, the buffer flexible support beam 115 is connected to the inner shaft torsion beam 111.

[0088] In one embodiment, the high-bandwidth MEMS scanning mirror chip 100 is a frameless motion structure, that is, there is no motion frame 113 between the micro-mirror 120 and the substrate 130; the flexible torsion beam can be twisted around both the inner and outer axes, and there are a total of four flexible torsion beams, two of which are symmetrically arranged along one torsion axis of the inner and outer axes, and the other two flexible torsion beams are symmetrically arranged along the other torsion axis. The flexible torsion beams connect the micro-mirror 120 to the peripheral substrate 130. When the micro-mirror 120 undergoes biaxial torsion, there is biaxial inter-axis coupling, and twisting along one torsion axis will affect the torsion angle of the micro-mirror 120 on the other torsion axis.

[0089] Specifically, the high-bandwidth scanning mirror device 300 can be a single-axis or dual-axis MEMS scanning mirror and can use the technical solutions of the present invention, and are all within the protection scope of the present invention.

[0090] Preferably, when the high-bandwidth scanning mirror device is a dual-axis scanning mirror device, the scanning feedback control of the scanning inner axis 161 and the scanning outer axis 162 respectively use an independent corresponding control channel to receive the feedback control signal from the feedback control chip 230, and a cross control signal is set between the two control channels to eliminate the inter-axis coupling between the two axes of the dual-axis scanning mirror device.

[0091] In one embodiment, the micro-mirror 120 is a silicon micro-mirror 120 .

[0092] In one embodiment, the shape of the micro-reflector 120 is one of circular, elliptical, square, and rectangular. The surface of the micro-reflector 120 is coated with an optical high-reflection film, and the material type of the optical high-reflection film is gold, silver, aluminum, or dielectric film.

[0093] Specifically, the micro-reflector 120 can be divided into three sizes according to its mirror size: small, medium and large. The size of the small-sized mirror is 0.2 mm to 1 mm, and the mirror thickness is 5 μm to 50 μm; the size of the medium-sized mirror is 1 mm to 3 mm, and the mirror thickness is 20 μm to 200 μm; the size of the large-sized mirror is a plane reflector of 3 mm to 20 mm, and the mirror thickness is 50 μm to 500 μm.

[0094] Preferably, when the micro-mirror 120 is a large-sized mirror, the mirror dynamic deformation buffer structure is provided between the inner-axis torsion beam 111 and the micro-mirror 120 .

[0095] In one embodiment, the high-bandwidth MEMS scanning mirror device 300 is a single-axis scanning mirror device.

[0096] In one embodiment, the high-bandwidth MEMS scanning mirror device 300 is a dual-axis scanning mirror device.

[0097] In one embodiment, the high-bandwidth MEMS scanning mirror device 300 is a three-axis scanning mirror device. Specifically, the high-bandwidth MEMS scanning mirror device 300 may also be other multi-axis scanning mirror devices as needed.

[0098] In one embodiment, the preset high-bandwidth feedback control algorithm used by the feedback control chip 230 is a PID algorithm, which processes the real-time angle signal and the target angle signal through the PID algorithm to generate an adjustment closed-loop feedback drive signal.

[0099] The existing technology generally uses a "step drive" method to drive the MEMS scanning mirror, directly driving the micro-mirror 120 to a preset torsion angle. However, this driving method is prone to overshoot, resulting in low control accuracy of the torsion angle of the micro-mirror 120 and a long scanning time to reach the preset torsion angle. The present invention uses a PID (Proportion Integral Differential) algorithm to provide a bidirectional torsional drive with high angular acceleration for the micro-mirror 120. As can be seen from the above content, under the same driving voltage, the driving torque of the high-bandwidth MEMS scanning mirror device 300 in the optimized solution is the same as that in the conventional design, but the torsional stiffness of the flexible torsion beam in the optimized design is only 1 / N that of the conventional design. 2 , so that the maximum angular acceleration value of the scanning drive in the optimization scheme is at least greater than the maximum angular acceleration value θ when the electric drive signal is "step drive" max (2πf) 2 N 2 times, where f is the working modal frequency of the high-bandwidth MEMS scanning mirror device 300 in the optimization solution of this embodiment, and its magnitude is the working modal frequency f in the ordinary design 寻常 1 / N times; setting the feedback control bandwidth of the PID algorithm to at least 2 times the designed working bandwidth of the high-bandwidth MEMS scanning mirror device 300, so that the feedback control bandwidth of the feedback control chip 230 is 5 to 15 times the working bandwidth of the MEMS scanning mirror chip; since the scanning working bandwidth BW of the high-bandwidth MEMS scanning mirror chip 100 is greater than or equal to the natural resonant frequency f of the working mode of the MEMS scanning mirror chip in the ordinary design 寻常 4N times, while the scanning bandwidth BW of the MEMS scanning mirror chip in the ordinary design is 寻常 is the natural resonant frequency f of the working mode of the MEMS scanning mirror chip in a common design 寻常 4 times, so that the scanning bandwidth BW of the high-bandwidth MEMS scanning mirror chip 100 can be as high as f 寻常 The bidirectional torsional drive combined with high-bandwidth PID feedback control can more flexibly adjust the drive of the micromirror 120 dynamically, greatly reducing the hysteresis of the feedback, thereby avoiding torsional overshoot, and at the same time solving the problem of insufficient rebound force and small deceleration acceleration caused by the reduced torsional stiffness of the flexible torsion beam during torsional deceleration of the micromirror 120, so that the micromirror 120 can ensure high-speed response during acceleration and deceleration, thereby greatly improving the scanning working bandwidth of the MEMS scanning mirror.

[0100] In one embodiment, N is greater than or equal to 1.1 and less than or equal to 20.

[0101] By limiting the range of N, the present invention ensures that the torsional stiffness of the flexible torsion beam is reduced, thereby reducing the rebound force and improving the initial acceleration. At the same time, the translational stiffness of the flexible torsion beam meets the strength requirements for the manufacture and application of the micro-reflector 120, thereby ensuring the reliability and service life of the MEMS scanning mirror structure. Specifically, the value of N is set based on the impact and vibration resistance of the flexible torsion beam during the torsional scanning process of the MEMS scanning mirror, so as to ensure the service life and structural reliability of the flexible torsion beam.

[0102] In one embodiment, the angle sensing detection structure 150 is a capacitive angle sensor or a piezoresistive angle sensor;

[0103] When the angle sensing detection structure 150 is a capacitive angle sensor, it can be a flat capacitive angle sensor or a comb-tooth capacitive angle sensor;

[0104] When the angle sensing detection structure 150 is a piezoresistive angle sensor, a silicon strain resistor is fabricated on the flexible torsion beam. The scanning of the micro-mirror 120 causes the strain of the flexible torsion beam to change linearly with the scanning angle. A Whitsted bridge circuit is formed by the silicon strain resistor and a reference resistor to detect the change in the silicon strain resistor, thereby sensing the scanning angle of the micro-mirror 120.

[0105] Example 2:

[0106] This embodiment provides a high-bandwidth MEMS scanning mirror device 300. The high-bandwidth MEMS scanning mirror device 300 has substantially the same features as the high-bandwidth MEMS scanning mirror device 300 in Example 1, except that:

[0107] In this embodiment, the diameter of the micro-mirror 120 is 0.2 mm to 1 mm, the thickness of the micro-mirror 120 is 5 μm to 50 μm, and N is greater than or equal to 5 and less than or equal to 20.

[0108] In the existing technology, MEMS scanning mirror devices with small mirror sizes of 0.2 mm to 1 mm have an operating modal eigenfrequency of around 1-2 kHz, and a scanning bandwidth of 500-1000 Hz under open-loop control and 4-8 kHz under closed-loop control. This can meet the needs of general applications, but it is difficult to meet the needs of higher scanning bandwidths, such as high-speed MEMS optical switching technology with microsecond switching times.

[0109] The present invention sets the N value of the small-sized micro-mirror 120 so that the small-sized micro-mirror 120 can maximize the scanning working bandwidth that can be achieved by the small-sized micro-mirror 120 while satisfying its torsional stiffness to ensure structural reliability, thereby facilitating the demand for MEMS scanning mirror devices with small-sized mirrors such as microsecond-level high-speed optical switches.

[0110] In one embodiment, the high-bandwidth MEMS scanning mirror device 300 is one of a MEMS high-speed optical phase shifter array, a MEMS microsecond high-speed optical switch, or a MEMS microsecond high-speed optical switch array.

[0111] Existing MEMS optical switches and their arrays only achieve optical path switching times of around 1ms, currently only enabling "optical line-level switching." This invention, by applying flexible torsion beams with reduced torsional stiffness to microsecond-level optical switches or optical switch arrays, can achieve high-efficiency optical switching of 10-100μs, or even 10μs-1μs, with an efficiency of 99%. This allows for MEMS all-optical burst packet switching with a large number of ports (256×256) with low optical loss (around 1-2dB), subverting the existing optical line-level switching architecture and achieving a "qualitative change" in switching technology for fiber-optic communication networks.

[0112] In one embodiment, the MEMS high-speed optical switch array is a dual-axis high-bandwidth MEMS scanning mirror device 300 including small-sized micro-mirrors 120. Its high-bandwidth MEMS scanning mirror chip 100 includes multiple micro-mirrors 120 and their corresponding structures such as flexible torsion beams, a driving structure 140 and an angle sensing detection structure 150. The multiple micro-mirrors 120 and their corresponding structures are arranged in a square array.

[0113] Example 3:

[0114] This embodiment provides a high-bandwidth MEMS scanning mirror device 300. The high-bandwidth MEMS scanning mirror device 300 has substantially the same features as the high-bandwidth MEMS scanning mirror device 300 in Example 1, except that:

[0115] In this embodiment, the diameter of the micro-reflector 120 is 3 mm to 20 mm, the thickness of the micro-reflector 120 is 50 μm to 500 μm, and N is less than 5.

[0116] The present invention sets the N value of the large-size micro-mirror 120 so that the large-size micro-mirror 120 can maximize the scanning working bandwidth that can be achieved by the large-size micro-mirror 120 while satisfying its torsional stiffness to ensure structural reliability, thereby avoiding the problem of flexible torsion beam breakage or poor reliability due to excessive torsional stiffness in the process of improving the working bandwidth. This is conducive to adapting to the bandwidth and structural stiffness requirements of MEMS scanning mirrors for large-size mirrors in applications such as precision tracking of space laser communication terminals, image stabilizers or laser pointing stabilizers for vehicle-mounted or airborne motion platforms, etc.

[0117] In one embodiment, the high-bandwidth MEMS scanning mirror device 300 is one of a MEMS fast-reflection mirror, an image stabilizer, a laser pointing stabilizer, a high-speed laser processing scanning mirror, or a high-speed 3D laser printing scanning mirror.

[0118] As the mirror radius R increases, the moment of inertia I of the MEMS scanning mirror will increase at the 4-5th power of the mirror radius R, resulting in a sharp drop in the operating modal resonant frequency of the large-size mirror MEMS scanning mirror. When the mirror diameter increases to 10 mm, the operating modal frequency of the MEMS scanning mirror drops to about 100-200 Hz. Under the existing MEMS feedforward open-loop drive control technology, the operating bandwidth of the large-size mirror MEMS scanning mirror can only reach 50-100 Hz. Using closed-loop feedback control, the operating bandwidth of the large-size mirror MEMS scanning mirror can only reach 400-800 Hz. Compared with the scanning mirror device of the small-size mirror, the achievable operating bandwidth is lower and cannot meet the demand for a bandwidth greater than 1000 Hz in fast scanning applications.

[0119] The present invention applies a flexible torsion beam that reduces torsional stiffness to a large-sized MEMS scanning mirror device, thereby greatly improving the scanning working bandwidth that can be achieved by the large-sized MEMS scanning mirror device and meeting the demand for scanning working bandwidth in large-sized mirrors.

[0120] In one embodiment, the MEMS fast reflector is a dual-axis high-bandwidth MEMS scanning mirror device 300 including a large-size micro-mirror 120 .

[0121] Example 4:

[0122] This embodiment provides a high-bandwidth MEMS scanning mirror device 300. The high-bandwidth MEMS scanning mirror device 300 has substantially the same features as the high-bandwidth MEMS scanning mirror device 300 in Example 1, except that:

[0123] In this embodiment, the diameter of the micro-mirror 120 is 1 mm to 3 mm, the thickness of the micro-mirror 120 is 20 μm to 200 μm, and N is greater than or equal to 4 and less than or equal to 15.

[0124] The present invention sets the N value of the medium-sized micro-reflector 120 so that the medium-sized micro-reflector 120 can maximize the scanning working bandwidth that can be achieved by the medium-sized micro-reflector 120 while satisfying its torsional stiffness to ensure structural reliability, thereby avoiding the problem of flexible torsion beam breakage or poor reliability due to excessive torsional stiffness in the process of increasing the working bandwidth.

[0125] Example 5:

[0126] This embodiment provides a high-bandwidth MEMS scanning mirror device 300. The high-bandwidth MEMS scanning mirror device 300 has substantially the same features as any one of the high-bandwidth MEMS scanning mirror devices 300 in Embodiments 1 or 3, except that:

[0127] In this embodiment, Figure 1-Figure 3 As shown, the high-bandwidth MEMS scanning mirror chip 100 of the high-bandwidth MEMS scanning mirror device 300 is a MEMS dual-axis scanning mirror chip, which uses an electrostatic flat-panel driver as a driving structure 140 to drive the micro-mirror 120 of the silicon mirror to scan, and a capacitive sensor as an angle sensing detection structure 150 to detect the scanning angle of the micro-mirror 120. A motion frame 113 is used to connect the micro-mirror 120 and the substrate 130 to achieve dual-axis scanning of a single micro-mirror 120; the high-bandwidth MEMS scanning mirror device 300 is a MEMS fast mirror, which has significant technical and cost advantages compared to traditional electromechanical fast mirrors.

[0128] In this embodiment, the high-bandwidth MEMS scanning mirror chip 100 includes a flexible torsion beam, a micro-mirror 120, a substrate 130, a driving structure 140 and an angle sensing detection structure 150; the flexible torsion beam includes an inner axis torsion beam 111 and an outer axis torsion beam 112, the driving structure 140 includes an inner axis electrostatic flat plate driver and an outer axis electrostatic flat plate driver, the angle sensing detection structure 150 includes an inner axis scanning angle sensor and an outer axis scanning angle sensor; the high-bandwidth MEMS scanning mirror chip 100 also includes a dynamic deformation buffer structure, a motion frame 113 and an electrode pad 133, the dynamic deformation buffer structure includes a buffer The flexible support beam 115 and the flexible support microstructure 114 include an even number of buffering flexible support beams 114, which are symmetrically arranged with the scanning inner axis 161 and the scanning outer axis 162 as the symmetry axes. One end of the flexible support microstructure 114 supports the micro mirror 120, and the other end is connected to the buffering flexible support beam 115. At the same time, the buffering flexible support beam 115 is connected to the inner axis torsion beam 111. The substrate 130 and the MEMS wafer with structures such as the flexible torsion beam and the micro mirror 120 are bonded together using an Au layer as a bonding layer 131 using a MEMS bulk silicon process based on Au-Si bonding.

[0129] Based on the application requirements of precise tracking in space laser communication systems, the key specifications of MEMS fast-reflecting mirrors are: 1) silicon mirror diameter 10mm; 2) dual-axis scanning angle range ±2.6mrad (mechanical angle); 3) dual-axis scanning bandwidth not less than 1kHz; 4) scanning accuracy 1μrad (mechanical angle); 5) mirror surface accuracy λ / 20 (measurement wavelength λ = 632.8nm); 6) shock acceleration resistance greater than 500G (gravitational acceleration unit 1G = 10m / s 2 ).

[0130] According to the index requirements of MEMS fast reflection mirror, the structure design of MEMS dual-axis scanning mirror chip is as follows:

[0131] 1) The diameter of micromirror 120 is 10 mm. The surface of micromirror 120 is coated with a 50 nm Ti / 200 nm Au high-reflection film 121, which has a reflectivity of up to 98.5% for infrared lasers operating at a wavelength of 1550 nm. To ensure that micromirror 120 achieves a high-precision static surface shape of λ / 20 and to reduce dynamic deformation of the silicon mirror during high-speed scanning, the mirror thickness of micromirror 120 is 400 μm.

[0132] 2) A dynamic deformation buffer structure including a buffering flexible support beam 115 and a flexible support microstructure 114 is used to significantly reduce the dynamic motion deformation of the micro-reflector 120. The dynamic deformation buffer structure provides uniform mechanical support and dynamic stress buffering for the micro-reflector 120, thereby significantly reducing the dynamic deformation of the mirror surface caused by high angular acceleration during high-speed scanning. Figure 1 As shown, the flexible support microstructure 114 is composed of 8 buffer flexible support beams 114, each of which has a beam length of 100 μm, a beam width of 15 μm, and a beam thickness of 400 μm. The 8 buffer flexible support beams 114 are radially distributed with equal angular spacing from the center of the micro-reflector 120; among them, there are 2 buffer flexible support beams 114 coaxial with the inner scanning axis 161, 2 buffer flexible support beams 114 coaxial with the outer scanning axis, and the other 4 buffer flexible support beams 114 are distributed along four directions at 45° to the scanning inner axis 161 and the scanning outer axis 162; one end of the flexible support microstructure 114 is connected to the micro-reflector 120, and the other end is connected to the buffer flexible support beam 115, so as to realize uniform and stress-relieving support for the micro-reflector 120, and ensure that the mirror surface of the micro-reflector 120 can still maintain high surface accuracy during high-speed scanning; the buffer flexible support beam 115 is a circular ring structure with a ring width of 300μm and a ring thickness of 400μm.

[0133] 3) If Figure 1As shown, the flexible torsion beam includes an inner-axis torsion beam 111 and an outer-axis torsion beam 112; the inner-axis torsion beam 111 has a beam length of 520 μm, a beam width of 28 μm, and a beam thickness of 400 μm, and includes two inner-axis torsion beams 111, one end of each inner-axis torsion beam 111 is connected to the buffer flexible support beam 115, and the other end is connected to the motion frame 113, so as to support the micro-mirror 120 and the dynamic deformation buffer structure; the outer-axis torsion beam 112 has a beam length of 520 μm, a beam width of 28 μm, and a beam thickness of 400 μm, and includes two outer-axis torsion beams 112, one end of each outer-axis torsion beam 112 is connected to the motion frame 113, and the other end is connected to the substrate 130 around the high-bandwidth MEMS scanning mirror chip 100.

[0134] 4) The high-bandwidth MEMS scanning mirror chip 100 is manufactured on a single-crystal silicon substrate 130, and the substrate 130 also includes a peripheral substrate 134 surrounding the high-bandwidth MEMS scanning mirror chip 100. Figure 2 As shown, an insulating oxide layer 132 with a thickness of 2 μm is grown on the substrate 130; four driving electrodes 141 of the driving structure 140 made of Au material are arranged symmetrically on the surface of the insulating oxide layer 132, as shown in FIG. Figure 5 As shown, the four driving electrodes 141 are fan-shaped figures of the same size, with a central angle (vertex angle) of 90° and a radius of 4 mm. The driving electrodes 141 made of Au material have a thickness of approximately 1 μm. A linear insulating groove 143 is provided between two adjacent driving electrodes 141 for insulation isolation. Each driving electrode 141 is led out from the corresponding linear insulating groove 143 to the electrode pad 133 of the high-bandwidth MEMS scanning mirror chip 100 through a driving electrode lead 142 electrically connected to the driving electrode 141. The driving electrode lead 142 is made of Au. The width of each linear insulating groove 143 is 100 μm. Each driving electrode lead 142 is located on the center line of the linear insulating groove 143. The width of the driving electrode lead 142 is 20 μm, and the distance between the driving electrode lead 142 and other sensing electrodes 151 and the driving electrode 141 is 40 μm.

[0135] like Figure 5As shown, on substrate 130, around the periphery of drive electrode 141, angle sensing structure 150 is symmetrically arranged with Au sensing electrodes 151. These four sensing electrodes 151 are quarter-circular rings of the same size, with a corresponding central angle of 90° and a minimum distance between the inner and outer diameters of each ring of 0.9 mm. The thickness of sensing electrodes 151 is approximately 1 μm. Each sensing electrode 151 is connected to the electrode pad 133 of the high-bandwidth MEMS scanning mirror chip 100 via a sensing electrode lead 152, each 50 μm wide. Adjacent Au driving electrodes 141 and Au sensing electrodes 151 are electrically isolated by linear insulation trenches 143 and circular insulation trenches 153, each 50 μm wide.

[0136] like Figure 2-Figure 3 As shown, all drive electrodes 141 and sensor electrodes 151 are located directly below the micromirror 120. An air gap 170 is provided between the drive electrodes 141, sensor electrodes 151, and the micromirror 120. Air gap 170 is 40 μm high to prevent the pull-in effect of electrostatic plate drive. The surface of the micromirror 120 is grounded, serving as a common ground electrode. Together with the four drive electrodes 141, it forms four drive plate capacitors, and together with the four sensor electrodes 151, it forms four sensor plate capacitors.

[0137] 5) The driving structure 140 of the high-bandwidth MEMS dual-axis scanning mirror chip adopts an electrostatic flat-plate driver, including an inner-axis electrostatic flat-plate driver and an outer-axis electrostatic flat-plate driver, which respectively drive the micro-mirror 120 around its inner scanning axis 161 and outer scanning axis 162 to achieve bidirectional (clockwise and counterclockwise) torsional scanning.

[0138] The internal-axis electrostatic flat-plate driver includes two internal-axis electrostatic flat-plate drivers arranged symmetrically about the scanning internal axis 161, forming a differential internal-axis electrostatic flat-plate driver. Driven by a bias DC power supply V0 (100V) and a programmable power supply V1 (bipolar, 60V), the two internal-axis electrostatic flat-plate drivers implement "push-pull" electrostatic torsional drive, enabling bidirectional electrical signal-controlled torsional scanning. In other words, whether scanning clockwise or counterclockwise, the voltage value and polarity of the programmable power supply V1 can be controlled to control the magnitude and direction of the scanning angular acceleration (either positive or negative, assuming a positive value for counterclockwise and a negative value for clockwise). This enables fully electrically controlled and flexible drive control of the micromirror 120, enabling flexible drive control of the micromirror 120 by the feedback control chip 230. When the voltage of the bipolar programmable power supply V1 is positive (i.e., a positive value), the inner-shaft electrostatic flat-plate driver rotates counterclockwise around the scanning inner shaft 161. Similarly, when the voltage of the bipolar programmable power supply V1 is negative (i.e., a negative value), the inner-shaft electrostatic flat-plate driver rotates clockwise around the scanning inner shaft 161. Controlling the voltage of the programmable power supply V1 can control the magnitude of the inner-shaft electrostatic drive torque τ1. The electrostatic inner shaft driving torque τ1 can be decomposed into two parts τ11 and τ12. One part (τ11) is used to overcome the elastic rebound torque of the inner shaft torsion beam 111 (the driving torque overcomes an elastic rebound torque that increases linearly with the scanning angle, thereby generating an angular acceleration curve that rapidly decays from the initial angular acceleration to zero), and the other part (τ12) realizes the accelerated twisting of the micro mirror 120 (including the dynamic deformation buffer structure) around the inner shaft (the net increase / decrease in the angular acceleration of the angular velocity of the micro mirror 120), that is, the angular acceleration scanning of the inner shaft increment, thereby accelerating the scanning motion of the micro mirror 120 and realizing high-speed scanning. It should be noted that only when the inner-axis electrostatic drive torque τ1 exceeds the partial torque of the inner-axis torsion beam 111's rebound torque can it be converted into a net inner-axis angular acceleration (or negative angular acceleration) on the micro-mirror 120. Therefore, to achieve high-speed scanning, the inner-axis electrostatic flat-plate driver needs to provide a sufficiently large drive torque that exceeds the elastic recovery torque of the inner-axis torsion beam 111, thereby generating a sufficiently large scanning angular acceleration of the micro-mirror 120. This is significantly different from existing MEMS scanning mirror drive technology, which differs in that existing MEMS scanning mirror drive technology only provides the drive torque τ11, i.e., the elastic rebound torque of the inner-axis torsion beam 111 corresponding to the specified scanning angle, as the driving torque. Of course, in order to ensure that the micro-mirror 120 quickly and accurately reaches the specified scanning angular position, the inner-axis electrostatic flat-plate driver also needs to be able to provide sufficient negative angular acceleration (i.e., deceleration). Feedback control is used to ensure that the micro-mirror 120 does not overshoot or jitter after reaching the specified angular position, thereby achieving the maximum scanning operating bandwidth. This is achieved by the feedback control chip 230.

[0139] The external-axis electrostatic flat-plate driver comprises two external-axis electrostatic flat-plate drivers arranged symmetrically around the scanning external axis 162, forming a differential external-axis electrostatic flat-plate driver. Driven by a bias DC power supply V0 (100V) and a programmable power supply V2 (bipolar, 60V), the two external-axis electrostatic flat-plate drivers implement push-pull electrostatic torsional drive, enabling bidirectional torsional scanning controlled by electrical signals. When the voltage of the bipolar programmable power supply V2 is positive, the external-axis electrostatic flat-plate driver drives the scanning external axis 162 in a counterclockwise torsional direction; when the voltage of the bipolar programmable power supply V2 is negative, the external-axis electrostatic flat-plate driver drives the scanning external axis 162 in a clockwise torsional direction. Controlling the voltage V2 controls the external-axis drive torque τ2. The external-axis drive torque τ2 can be decomposed into two parts, τ21 and τ22. One part (τ21) overcomes the elastic rebound torque of the external-axis torsion beam 112, while the other part (τ22) accelerates the twisting of the micromirror 120 (including the dynamic deformation buffer structure, the internal-axis torsion beam 111, and the motion frame 113) around the scanning external axis 162, i.e., external-axis angular acceleration scanning. Similarly, only when the electrostatic external-axis drive torque τ2 exceeds the partial torque of the external-axis torsion beam 112 rebound torque can it be converted into external-axis angular acceleration (or negative angular acceleration) of the micromirror 120, thereby achieving high-speed scanning of the micromirror 120.

[0140] 6) The dual-axis high-bandwidth MEMS scanning mirror chip 100 uses a capacitive angle sensor to detect the scanning angle position in real time, including an inner axis scanning angle sensor and an outer axis scanning angle sensor, which respectively detect the scanning angle values ​​of the micro-mirror 120 around the inner scanning axis 161 and the outer scanning axis 162, and can realize real-time measurement of bidirectional scanning angle values ​​(assuming that the counterclockwise scanning angle is positive and the clockwise scanning angle is negative).

[0141] The inner axis scanning angle sensor includes two inner axis scanning angle sensors arranged symmetrically with respect to the scanning inner axis 161, forming a differential inner axis scanning angle sensor. The design of the differential scanning angle sensor can eliminate a large amount of common mode interference signals, while the sensitivity can be doubled.

[0142] The outer-axis scanning angle sensor includes two outer-axis scanning angle sensors arranged symmetrically with respect to the scanning outer axis 162 , forming a differential inner-axis scanning angle sensor.

[0143] Example 6:

[0144] This embodiment provides a design method for a high-bandwidth MEMS scanning mirror device 300. The design method is used to design the high-bandwidth MEMS scanning mirror device 300 described in any one of Embodiments 1-5. The design method includes:

[0145] According to the driving structure 140 and driving voltage of the high-bandwidth MEMS scanning mirror device 300, the maximum torque that the high-bandwidth MEMS scanning mirror device 300 can provide to the micro-mirror 120 is calculated by simulation tools as τ, and the design target of the maximum scanning angle of the micro-mirror 120 of the high-bandwidth MEMS scanning mirror device 300 is θ max ;

[0146] Calculate the torsional stiffness K of the flexible torsion beam of the high-bandwidth MEMS scanning mirror device 300 θ =τ / (θ max N 2 ), N is a number greater than 1; the torsional stiffness is K θ The flexible torsion beam serves as a torsion connection between the micro-mirror 120 and the motion frame 113 of the high-bandwidth MEMS scanning mirror device 300, and between the motion frame 113 and the substrate 130 (peripheral substrate 134).

[0147] In the existing technology, the torsional stiffness of the flexible torsion beam is generally increased to improve the torsional rebound force and increase the acceleration during deceleration. However, at the same time, it will also cause excessive rebound resistance during the initial acceleration of the torsion, resulting in limited acceleration during acceleration, so that the overall scanning working bandwidth of the MEMS scanning mirror device is always limited and cannot be greatly improved. When the torsional stiffness of the flexible torsion beam is increased to a certain extent, the improvement of the scanning working bandwidth is limited and cannot be further improved, which makes it difficult to meet the high requirements of the current high-speed scanning application scenarios for the scanning working bandwidth of the MEMS scanning mirror.

[0148] The present invention breaks the conventional design method for improving the scanning working bandwidth of the MEMS scanning mirror, reversely reduces the torsional stiffness of the flexible torsion beam, and solves the problem of limited acceleration of the initial torsional acceleration caused by the increase in torsional stiffness. At the same time, a bidirectional torsional drive is used in conjunction with the feedback control chip 230 to perform flexible real-time high-bandwidth feedback control of the driving state during deceleration, thereby improving the acceleration during deceleration, thereby improving the acceleration in both the acceleration and deceleration stages, thereby significantly improving the overall scanning working bandwidth of the MEMS scanning mirror device.

[0149] To illustrate the significant technical advantages of the design method for the high-bandwidth MEMS scanning mirror device 300 of the present invention, this embodiment is compared with an existing MEMS scanning mirror design method (conventional design method). In the following design method comparison, the micro-reflectors 120 are all silicon mirrors, the buffer structure is the dynamic deformation buffer structure described in Example 4, and the drive structure 140 is an electrostatic drive. The silicon mirror parameters, buffer structure parameters, electrostatic drive parameters, and drive voltage remain unchanged, as shown in Table 1.

[0150] Table 1 Microstructure parameters of high-bandwidth MEMS scanning mirror (excluding flexible torsion beam)

[0151]

[0152]

[0153] By setting the sizes of the corresponding flexible torsion beams in the design scheme of the present invention and the conventional design scheme to be different, the torsional stiffness of the corresponding flexible torsion beams in the two schemes is different, the driving torque required to obtain the same static torsion angle is different, the torsional operating modal frequency of the flexible torsion beam is different, and the scanning net angular acceleration is different. The specific parameter differences between the two schemes are compared and shown in Table 2.

[0154] Table 2 Comparison of the patented design scheme and the conventional design scheme for the MEMS scanning mirror flexible torsion beam structural parameters and scanning mirror electromechanical performance parameters

[0155]

[0156]

[0157] Specifically, the "usual design" of a MEMS scanning mirror is as follows:

[0158] 1) Based on the application requirements of the MEMS scanning mirror device, the design of the electrostatic flat-panel driver, and the selection of the driving power supply, the design parameters shown in Table 1 are obtained, including chip size, microstructure process parameters (limited by the existing MEMS processing technology), driving mode, and driving signal size. The maximum driving torque (torsion torque) τ of the electrostatic driver of the MEMS scanning mirror device is obtained through calculation and simulation. max It is 3.913μNm, and the maximum driving torque of the inner and outer shafts is the same;

[0159] 2) Based on the index requirement of the angular scanning range of the MEMS scanning mirror (-2.6mrad to +2.6mrad), under the guidance of the design concept of "maximizing the working mode eigenfrequency of the MEMS scanning mirror", the torsional stiffness of the flexible torsion beam of the MEMS scanning mirror is maximized in the design. The torsional stiffness of the inner axis in the design torsional stiffness of the flexible torsion beam is obtained as follows: K θ内 =τ max内 / θ max内 =1505μNm / rad, the torsional stiffness of the outer shaft is: K θ外 =τ max外 / θ max外 =1505μNm / rad;

[0160] 3) According to the formula f0=(2π) -1 (K θ / I)1 / 2 , where f0 is the eigenfrequency of the scanning working mode in the usual design, K θ is the torsional stiffness of the flexible torsion beam, I is the moment of inertia of the MEMS scanning mirror around the scanning axis, and the intrinsic frequency f of the inner axis scanning working mode of the MEMS scanning mirror is obtained 0内 =287.7Hz, external axis scanning working mode eigenfrequency f 0外 =242.9Hz;

[0161] 4) Through PID feedback control, the maximum possible driving torque is generated under the drive of the maximum possible driving voltage, and thus the maximum possible angular acceleration value is generated. Its maximum operating bandwidth is 4 times the operating modal frequency f0, that is, the maximum scanning working bandwidth of the inner axis is 1150.8 Hz, and the maximum scanning working bandwidth of the outer axis is 971.4 Hz.

[0162] And the optimization design method according to the present invention is as follows:

[0163] 1) Based on the application requirements of the high-bandwidth MEMS scanning mirror device 300, the design of the electrostatic driver as the driving structure 140, and the selection of the driving power supply, the design parameters shown in Table 1 are obtained, and the maximum driving torque τ of the MEMS driver is obtained by calculation and simulation. max The design parameters of this scheme and the “normal design” in Table 1 are the same to ensure that the two design schemes have the same irrelevant variables except for the research target variables related to torsional stiffness.

[0164] 2) Take N=2 to obtain the design torsional stiffness of the high-bandwidth MEMS scanning mirror chip 100

[0165] Inner shaft: K θ内(优化) =τ max内 / (θ max内 ×N 2 )=3.913μNm / (2.6mrad×2 2 )=376μNm / rad, and the corresponding design parameters of the inner shaft flexible torsion beam are: length 520μm, width 28μm, and thickness 400μm;

[0166] External axis: K θ外(优化) =τ max外 / (θ max外 ×N 2 )=3.913μNm / (2.6mrad×2 2 )=376μNm / rad, and the corresponding design parameters of the external axis flexible torsion beam are: length 520μm, width 28μm, and thickness 400μm;

[0167] 3) According to the formula f=(2π) -1 (K θ / I) 1 / 2 ,get

[0168] The intrinsic frequency of the internal axis scanning working mode of the high-bandwidth MEMS scanning mirror chip 100 is: 内 ≈f 0内 / N=f 0内 / 2=143.8Hz.

[0169] The eigenfrequency of the external axis scanning working mode of the high-bandwidth MEMS scanning mirror chip 100 is: f 外 ≈f 0外 / N=f 0外 / 2 = 115.9 Hz (due to the slight difference in moving mass and radius caused by different torsional stiffness, which cannot be eliminated, the moment of inertia is not exactly the same. As a result, f in this solution is not exactly half of f0 in the ordinary design, but there is a slight change).

[0170] 4) Through PID feedback control, under the drive of the maximum possible drive signal, the maximum possible drive torque is generated, and thus the maximum possible angular acceleration value is generated. Its scanning working bandwidth is 4N = 8 times the modal frequency f0 in the conventional design, that is, the inner axis scanning working bandwidth is 2300 Hz, and the outer axis scanning working bandwidth is 1855 Hz. Compared with the "conventional design", the scanning working bandwidth of the high-bandwidth MEMS scanning mirror chip 100 is increased by N times. In this embodiment, the scanning working bandwidth is increased by 2 times.

[0171] The above-mentioned optimized design scheme of this patent, through the optimized design of the flexible torsion beam, in this embodiment, under the condition that the design constraints remain unchanged, the operating bandwidth of the high-bandwidth MEMS scanning mirror chip 100 is increased by 2 times compared with the "conventional design" MEMS scanning mirror, showing a significant technical advantage of high-bandwidth scanning.

[0172] In another preferred embodiment, when N=3, the operating bandwidth of the high-bandwidth MEMS scanning mirror chip 100 is increased by 3 times compared with the MEMS scanning mirror of “conventional design”.

[0173] In another preferred embodiment, when N=4, the operating bandwidth of the high-bandwidth MEMS scanning mirror chip 100 is increased by 4 times compared with the MEMS scanning mirror of “conventional design”.

[0174] It should be noted that there is a limit to the value of N. The limit of N depends on the technical requirements for the seismic resistance of the high-bandwidth MEMS scanning mirror device 300 in the working scenario. Because as the value of N increases, the beam width of the flexible torsion beam becomes appropriately narrower, or the beam length becomes appropriately longer, or the beam width becomes appropriately narrower and the beam length becomes appropriately longer at the same time. Under the premise of meeting the application requirements of the device, the value of N is preferably 2-5. In this embodiment, the silicon mirror is large in size (mirror diameter is 10mm) and very thick (mirror layer thickness is 400μm), so the value of N cannot be too large. If the silicon mirror is small in size (mirror diameter is about 1mm) and thin in thickness (mirror thickness is 20-30μm), the value range of N can be expanded to 5-20. The specific selection of N can refer to the range of mirror sizes corresponding to Examples 1-4.

[0175] In summary, the high-bandwidth MEMS scanning mirror device and the design method thereof of the present invention can be realized by setting the torsional stiffness of the flexible torsion beam to the conventional design torsional stiffness τ / θ max 1 / N 2 , reducing the torsional stiffness of the flexible torsion beam to increase the acceleration of the micromirror during torsional acceleration, coordinating the feedback control of the torsional motion state by the bidirectional torsional drive and feedback control chip, increasing the acceleration of the micromirror during torsional deceleration, and avoiding overshoot caused by excessive torsional amplitude of the scanning mirror, thereby greatly improving the scanning working bandwidth achievable by the scanning mirror device; at the same time, by adopting different degrees of torsional stiffness reduction for micromirrors of different sizes, the structural strength of the micromirror is ensured while optimizing the scanning working bandwidth; in addition, the PID algorithm is used for torsional feedback control of the micromirror to further improve the achievable scanning working bandwidth; finally, by reducing the torsional stiffness of the torsional beam instead of the conventional method of increasing the torsional stiffness, and coordinating the feedback control to improve the working bandwidth, the design thinking inertia of MEMS scanning mirror devices to improve the bandwidth is broken, and a significant effect of greatly improving the scanning working bandwidth of MEMS scanning mirror devices is produced.

[0176] Therefore, the present invention effectively overcomes various shortcomings of the prior art and has high industrial utilization value.

[0177] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A high-bandwidth MEMS scanning mirror device, characterized in that: The high-bandwidth MEMS scanning mirror device includes: a high-bandwidth MEMS scanning mirror chip, a power drive chip, an angle sensing detection circuit chip, a feedback control chip and an input / output connector; The high-bandwidth MEMS scanning mirror chip includes a flexible torsion beam, a micro-mirror, a substrate, a drive structure, and an angle sensing detection structure. The micro-mirror and the substrate are torsionally connected via the flexible torsion beam. The drive structure controls the micro-mirror to perform torsional motion relative to the substrate. The angle sensing detection structure is used to detect the real-time torsion angle of the micro-mirror. The maximum torque that the drive structure can provide to the micro-mirror is τ, and the maximum scanning angle of the micro-mirror is θ. max When the torsional stiffness K of the flexible torsion beam is θ =τ / (θ max N 2 ), N is a number greater than 1; The power driver chip is electrically connected to the driving structure to control the driving state of the micro-mirror by the driving structure; the angle sensing detection circuit chip is electrically connected to the angle sensing detection structure to receive and process the real-time torsion angle of the micro-mirror detected by the angle sensing detection structure to obtain a real-time angle signal; the input / output connector is electrically connected to the external control system to receive the target angle signal input by the external control system; the feedback control chip is electrically connected to the angle sensing detection circuit chip, the power driver chip, and the input / output connector to receive the real-time angle signal calculated by the angle sensing detection circuit chip and the target angle signal received by the input / output connector, and obtains an adjusted closed-loop feedback driving signal through a preset high-bandwidth feedback control algorithm, and transmits the adjusted closed-loop feedback driving signal to the power driver chip, and controls the driving state of the micro-mirror driven by the driving structure through the power driver chip, and the power driver chip controls the driving structure to drive the micro-mirror to twist in both directions.

2. The high-bandwidth MEMS scanning mirror device according to claim 1, characterized in that: The high-bandwidth MEMS scanning mirror chip includes M micro-mirrors arranged in an array, each of the micro-mirrors has a corresponding flexible torsion beam, a driving structure and an angle sensing detection structure, and the M micro-mirrors are on the same substrate, where M is an integer greater than or equal to 1.

3. The high-bandwidth MEMS scanning mirror device according to claim 1, characterized in that: The preset high-bandwidth feedback control algorithm adopted by the feedback control chip is a PID algorithm, which processes the real-time angle signal and the target angle signal through the PID algorithm to generate an adjustment closed-loop feedback drive signal.

4. The high-bandwidth MEMS scanning mirror device according to any one of claims 1 to 3, wherein: N is greater than or equal to 1.1 and less than or equal to 20.

5. The high-bandwidth MEMS scanning mirror device according to claim 4, characterized in that: The mirror diameter of the micro-reflector is 0.2 mm to 1 mm, the mirror thickness of the micro-reflector is 5 μm to 50 μm, and N is greater than or equal to 5 and less than or equal to 20.

6. The high-bandwidth MEMS scanning mirror device according to claim 5, characterized in that: The high-bandwidth MEMS scanning mirror device is one of a MEMS high-speed optical phase shifter array, a MEMS microsecond high-speed optical switch, or a MEMS microsecond high-speed optical switch array.

7. The high-bandwidth MEMS scanning mirror device according to claim 4, characterized in that: The mirror diameter of the micro-reflector is 3 mm to 20 mm, the mirror thickness of the micro-reflector is 50 μm to 500 μm, and N is less than 5.

8. The high-bandwidth MEMS scanning mirror device according to claim 7, characterized in that: The high-bandwidth MEMS scanning mirror device is one of a MEMS fast-reflection mirror, an image stabilizer, a laser pointing stabilizer, a high-speed laser processing scanning mirror or a high-speed 3D laser printing scanning mirror.

9. The high-bandwidth MEMS scanning mirror device according to claim 4, characterized in that: The mirror diameter of the micro-reflector is 1 mm to 3 mm, the mirror thickness of the micro-reflector is 20 μm to 200 μm, and N is greater than or equal to 4 and less than or equal to 15.

10. A method for designing a high-bandwidth MEMS scanning mirror device, characterized in that: The design method is used to design the high-bandwidth MEMS scanning mirror device according to any one of claims 1 to 9, and the design method comprises: According to the driving structure and driving voltage of the high-bandwidth MEMS scanning mirror device, the maximum torque that the high-bandwidth MEMS scanning mirror device can provide to the micro-reflector is calculated by simulation tools as τ, and the design target of the maximum scanning angle of the micro-reflector of the high-bandwidth MEMS scanning mirror device is θ max ; Calculate the torsional stiffness K of the flexible torsion beam of the high-bandwidth MEMS scanning mirror device θ =τ / (θ max N 2 ), N is a number greater than 1; the torsional stiffness is K θ The flexible torsion beam serves as a torsional connection between the micro-mirror and the substrate of the high-bandwidth MEMS scanning mirror device.

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