Method for regulating and controlling nonlinearity of MEMS torsion beam

Abstract

The invention discloses a method for regulating and controlling the nonlinearity of an MEMS (Micro Electro Mechanical System) torsion beam, which is characterized in that the nonlinear rigidity of a multi-fold torsion beam is regulated and controlled by regulating the linear rigidity distribution of different beams in the multi-fold torsion beam and the arm length of a U-shaped beam and regulating the nonlinear rigidity of a middle beam and an outer side beam of the multi-fold torsion beam, so that the aim of regulating, weakening or eliminating the nonlinearity of the torsion beam is fulfilled. According to the method, the rigidity of the multi-fold torsion beam is independently adjusted, the application range is wide, the non-linear rigidity of the multi-fold beam can be adjusted and controlled to be a positive value, zero and a negative value, a basis is provided for weakening or eliminating the nonlinearity of a torsion device, meanwhile, for the torsion device with the nonlinearity dominated by the torsion beam, the non-linear rigidity of the torsion beam is adjusted and controlled to be close to zero through the method, and the non-linear rigidity of the torsion beam is adjusted and controlled to be close to zero. For a torsion device of which the nonlinearity is dominated by other factors, the method is utilized to regulate and control the nonlinear rigidity of the torsion beam to be an opposite number of the nonlinear rigidity caused by other factors, so that the nonlinearity of the torsion device is freely weakened and eliminated.

Description

Technical Field

[0001] The invention belongs to the technical field of MEMS torsion beam control, and relates to a method for controlling the nonlinearity of a MEMS torsion beam. Background Art

[0002] The MEMS torsion beam acts as an elastic element to provide a restoring torque for the MEMS device with torsional motion. During the operation of the device, the external driving torque (which can be generated by common driving methods such as piezoelectric drive, electrostatic drive, electromagnetic drive, electrothermal drive and magnetostrictive drive) applies torque to the torsion beam, causing it to undergo elastic torsional deformation and generate a restoring torque. The nonlinearity of the MEMS torsion beam is manifested as a nonlinear relationship between the restoring torque and the angle of rotation, which is caused by the geometric nonlinearity generated by the strain-angle nonlinear relationship. The nonlinearity of the MEMS torsion beam causes the MEMS torsion device to exhibit nonlinear phenomena. At large angles, the amplitude-frequency response of the device jumps, and the device is difficult to operate at the maximum angle. The angle control is difficult, which greatly affects the stability of its resonant motion.

[0003] Methods for eliminating the nonlinear effects of MEMS torsion beams include directly weakening the nonlinearity of the MEMS torsion beam and using a driving torque with opposite nonlinear properties to offset it. Patent (CN102540459B) discloses a method of setting slits on a torsion beam, which weakens the geometric nonlinearity caused by different deformation states at different positions of the torsion beam due to different distances from the torsion center axis, thereby achieving the purpose of reducing the occurrence of nonlinear resonance under high-frequency drive. However, this method cannot completely eliminate the geometric nonlinearity of the torsion beam. The relatively simple straight beam structure makes the MEMS device area relatively large, and there are also many limitations in application. The paper (Scanning Micro-Mirror with an Electrostatic Spring for Compensation of Hard-Spring Nonlinearity) reports a method of using negative driving torque nonlinearity to offset positive torsion beam nonlinearity, successfully eliminating the nonlinear phenomenon of electrostatically driven MEMS micromirrors, but this solution is only applicable to electrostatic drive solutions and occasions with small turning angles, and has a limited scope of application.

[0004] Therefore, it is expected to achieve the regulation of the nonlinearity of the MEMS torsion beam through a special method to eliminate the nonlinearity of the MEMS torsion beam, or to use the nonlinearity of the MEMS torsion beam to offset the nonlinearity of the driving torque of the opposite nature, thereby achieving the purpose of weakening or eliminating the nonlinearity of the MEMS torsion device, eliminating the amplitude-frequency response jump of the MEMS device at a large rotation angle, and increasing the stability of its resonant motion. Summary of the invention

[0005] The purpose of the present invention is to solve the problem that in the prior art, when designing a MEMS torsion beam, the geometric nonlinearity of the MEMS torsion device cannot be weakened or eliminated, and at a large rotation angle, the amplitude-frequency response of the device exhibits a jump phenomenon, which affects the stability of the resonant motion, and to provide a method for regulating the nonlinearity of the MEMS torsion beam.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for regulating the nonlinearity of a MEMS torsion beam comprises the following steps:

[0008] According to the initial total linear stiffness of the torsion beam, the initial linear stiffness of the outer beam and the middle beam is given;

[0009] Given the initial arm length L of the U-shaped beam 1初 ;

[0010] Based on the given initial linear stiffness of the outer beam and the middle beam, the initial nonlinear stiffness k of the middle beam is obtained: 13初 > 0, the initial nonlinear stiffness k of the outer beam 23初 <0;

[0011] Control and increase the arm length L1 of the U-shaped beam, so that the nonlinear stiffness of the middle beam begins to increase and is greater than 0, the nonlinear stiffness of the outer beam begins to increase and is less than 0, and the initial total nonlinear stiffness of the torsion beam increases to the maximum peak value;

[0012] When the total nonlinear stiffness of the torsion beam is at the maximum peak value, the arm length of the U-shaped beam continues to increase. At this time, the nonlinear stiffness of the middle beam continues to increase, the nonlinear stiffness of the outer beam begins to decrease, and the total nonlinear stiffness of the torsion beam begins to gradually decrease.

[0013] A further improvement of the present invention is:

[0014] The initial linear stiffness of the outer beam and the middle beam is given according to the initial total linear stiffness of the torsion beam, including: making k 21初 =1.5*k 11初 , where k 21初 represents the initial linear stiffness of the outer beam, k 11初 represents the initial linear stiffness of the middle beam.

[0015] According to the initial total linear stiffness of the torsion beam, when the initial linear stiffness of the outer beam and the middle beam is given, when the ratio of the initial linear stiffness of the outer beam to the initial linear stiffness of the middle beam increases, the maximum peak value of the total nonlinear stiffness of the torsion beam increases;

[0016] When the ratio of the initial linear stiffness of the outer beam to the middle beam decreases, the maximum peak value of the total nonlinear stiffness of the torsion beam decreases.

[0017] When the initial linear stiffness ratio of the outer beam to the middle beam is 2.5, the maximum peak value of the total nonlinear stiffness of the torsion beam is positive.

[0018] When the initial linear stiffness ratio of the outer beam and the middle beam is 1, the maximum peak value of the total nonlinear stiffness of the torsion beam is negative.

[0019] When the initial total nonlinear stiffness of the torsion beam increases before reaching the maximum peak value, the increasing speed of the nonlinear stiffness of the middle beam is greater than the increasing speed after the total nonlinear stiffness of the torsion beam increases to the maximum peak value.

[0020] Increasing the initial total nonlinear stiffness of the torsion beam to the maximum peak value includes the following steps:

[0021] Increase the arm length L1 of the U-shaped beam, and the nonlinear stiffness k of the middle beam 13 Increase, and k 13 >0; nonlinear stiffness k of the outer beam 23 Increases, and the nonlinear stiffness k 23 <0; the total nonlinear stiffness k3 increases until it reaches 0, the nonlinearity decreases, and the total nonlinear stiffness k3 is 3初 Regulate between 0 and 0;

[0022] As the arm length L1 of the U-shaped beam is further increased, the nonlinear stiffness k of the middle beam 13 Increase, the nonlinear stiffness k of the outer beam 23 Increases to the maximum peak value, nonlinearity increases, and the total nonlinear stiffness k3 is between 0 and k 3最大 Between regulation.

[0023] The control process of gradually reducing the total nonlinear stiffness of the torsion beam to a negative value includes:

[0024] When the total nonlinear stiffness of the torsion beam is at its maximum peak, the arm length L1 of the U-shaped beam is further increased, and the nonlinear stiffness k of the middle beam is 13 Continue to increase, and the nonlinear stiffness k 13 >0; nonlinear stiffness k of the outer beam 23 Reduced, and the nonlinear stiffness k 23 <0; the total nonlinear stiffness k3 is reduced to 0, and the nonlinearity is reduced. At this time, the nonlinear stiffness k3 is k 3最大 Regulate between 0 and 0;

[0025] As the arm length L1 of the U-shaped beam is further increased, the nonlinear stiffness k of the middle beam 13 Continue to increase, the nonlinear stiffness k of the outer beam 23 Continue to decrease, and k 23 <0, the total nonlinear stiffness k3 is reduced to a negative value, and the nonlinearity increases. At this time, the nonlinear stiffness k3 is regulated between 0 and a negative value.

[0026] A MEMS torsion beam is prepared by control based on the method described in the present invention.

[0027] A MEMS torsion beam comprises a middle beam, and outer beams are distributed around the periphery of the middle beam;

[0028] The outer side beams include side beams and U-shaped beams. The side beams are parallel and symmetrically distributed on both sides of the middle beam. One end of the side beam is connected to the U-shaped beam, and the U-shaped beam is connected to the end close to the middle beam.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention discloses a method for regulating the nonlinearity of a MEMS torsion beam. By regulating the linear stiffness distribution of different beams in the MEMS multi-fold torsion beam and the arm length of the U-shaped beam, the nonlinear stiffness of the middle beam and the outer beam of the MEMS multi-fold torsion beam is regulated, thereby regulating the nonlinear stiffness of the MEMS multi-fold torsion beam, and achieving the purpose of regulating, weakening or eliminating the nonlinearity of the MEMS torsion beam. The method of the present invention independently regulates the stiffness of the MEMS multi-fold torsion beam and has a wide range of applications. The nonlinear stiffness of the MEMS multi-fold beam can be regulated to positive values, zero and negative values, providing a basis for weakening or eliminating the nonlinearity of the MEMS torsion device. At the same time, for a MEMS torsion device whose nonlinearity is dominated by the torsion beam, the nonlinear stiffness of the torsion beam is regulated to near zero by this method. For a MEMS torsion device whose nonlinearity is dominated by other factors, the nonlinear stiffness of the torsion beam is regulated to the opposite number of the nonlinear stiffness caused by other factors by this method, thereby freely weakening and eliminating the nonlinearity of the MEMS torsion device. In addition, this method uses a multi-fold torsion beam as an elastic element, which can increase the utilization rate of the space outside the torsion axis. Compared with a straight beam, it reduces the size of a single device, thereby reducing the average cost of a single device. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 is a flow chart of the method of the present invention;

[0033] Figure 2 is a graph showing the relationship between the nonlinear stiffness of each beam and the arm length of the U-shaped beam of the present invention, (where a represents the nonlinear stiffness k of the middle beam 13 Relationship diagram with the U-shaped beam arm length L1, overall the nonlinear stiffness k of the middle beam 13is greater than zero. As the length of the U-shaped beam L1 increases, the nonlinear stiffness k of the middle beam increases. 13 increases, and the speed gradually decreases; b represents the nonlinear stiffness k of the outer beam 23 Relationship diagram with the U-shaped beam arm length L1, overall the nonlinear stiffness k of the outer beam 23 Less than zero, as the length of the U-shaped beam L1 increases, the nonlinear stiffness k of the outer beam 23 It increases first and then decreases; c is the relationship diagram between the total nonlinear stiffness k3 and the U-beam arm length L1. With the increase of the U-beam arm length L1, the total nonlinear stiffness k3 increases first and then decreases; d is the relationship diagram between the total nonlinear stiffness k3 and the U-beam arm length L1 when the initial linear stiffness ratio of the outer beam and the middle beam is different. When the initial nonlinear stiffness ratio increases, the total nonlinear stiffness k3 increases as a whole. When the initial nonlinear stiffness ratio increases, the total nonlinear stiffness k3 decreases as a whole;)

[0034] Figure 3 A structural diagram of a MEMS multi-fold torsion beam of the present invention (where a represents a top view; b represents a stereogram);

[0035] Figure 4 A structural diagram of a MEMS multi-fold torsion beam of another structure of the present invention (where a represents a top view; b represents a stereogram);

[0036] Figure 5 This is a structural diagram of the MEMS multi-fold torsion beam assembly of the present invention;

[0037] Figure 6 This is a schematic diagram of the operation of the MEMS multi-fold torsion beam in Example 1 of the present invention;

[0038] Figure 7 This is a schematic diagram of the operation of the MEMS multi-fold torsion beam in Example 2 of the present invention.

[0039] Among them: 1-U-shaped beam; 2-side beam; 3-middle beam; 4-outer beam. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0041] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0043] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0044] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0045] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0047] See also Figure 1 The embodiment of the present invention discloses a method for regulating the nonlinearity of a MEMS torsion beam, by adjusting the linear stiffness distribution of different beams in the MEMS multi-fold torsion beam and the arm length of the U-shaped beam, and adjusting the nonlinear stiffness of the middle beam and the outer beam of the MEMS multi-fold torsion beam, thereby regulating the nonlinear stiffness of the MEMS multi-fold torsion beam. The nonlinear stiffness of the MEMS multi-fold torsion beam can be regulated to positive, zero and negative values, providing a basis for weakening or eliminating the nonlinearity of the MEMS torsion device.

[0048] When the nonlinearity of the MEMS torsion device is dominated by the nonlinearity of the torsion beam, the nonlinearity of the MEMS multi-fold beam is adjusted to near zero.

[0049] When the nonlinearity of the MEMS torsion device is dominated by the nonlinearity of the driving torque, the MEMS multi-fold beam is adjusted to a nonlinearity of opposite nature to offset the nonlinearity of the driving torque, thereby achieving the purpose of weakening or eliminating the nonlinearity of the MEMS torsion device.

[0050] The specific control method includes the following steps:

[0051] Step 1: Based on the initial total linear stiffness k 1初 , calculate the initial linear stiffness k of the middle beam and the outer beam 11初 and k 21初 , so that k 21初 =1.5*k 11初 , then k 11初 ≈1.67*k 1初 , k 21初 =2.5*k 1初 .

[0052] Design the multi-fold torsion beam so that the arm length L1 of the U-shaped beam is minimized, and the stiffness of the middle beam and the outer beam are k 11 ≈k 11初 and k 21 ≈k 21初 At this time, the initial nonlinear stiffness k of the middle beam is 13初 > 0, the initial nonlinear stiffness k of the outer beam 23初 <0, total initial nonlinear stiffness k 3初 <0.

[0053] Furthermore, in this step, the initial linear stiffness k of the outer beam and the middle beam is increased. 21初 and k 11初 The ratio of k 3峰值 , a larger positive value of k3 is obtained, and the value of k3 increases overall.

[0054] Reduce the initial linear stiffness k of the middle and outer beams 21初 and k 11初 The ratio can reduce the negative value of k3, obtain a smaller negative value of k3, and the overall value of k3 is reduced.

[0055] Step 2: Increase the length of the U-shaped beam arm L1 and the nonlinear stiffness k of the middle beam 13 (>0) increases, the nonlinear stiffness k of the outer beam 23 (<0) increases, the total nonlinear stiffness k3(<0) increases until it reaches 0, and the nonlinearity decreases until it is eliminated.3初 to 0.

[0056] Step 3: Continue to increase the U-shaped beam arm length L1 and the nonlinear stiffness k of the middle beam 13 (>0) increases, the nonlinear stiffness k of the outer beam 23 (<0) increases to the maximum, and the total nonlinear stiffness k3 increases to the maximum k 3最大 , the nonlinearity increases. Thus, the nonlinear stiffness k3 is set between 0 and k 3最大 Between regulation.

[0057] Step 4: Continue to increase the U-shaped beam arm length L1 and the nonlinear stiffness k of the middle beam 13 Basically unchanged, the nonlinear stiffness k of the outer beam 23 (<0) is reduced, the total nonlinear stiffness k3 is reduced to 0, and the nonlinearity is reduced. 3最大 to 0.

[0058] Step 5: Continue to increase the U-shaped beam arm length L1 and the nonlinear stiffness k of the middle beam 13 Basically unchanged, the nonlinear stiffness k of the outer beam 23 (<0) decreases, the total nonlinear stiffness k3 decreases to a negative value, and the nonlinearity increases. Thus, the nonlinear stiffness k3 is regulated between 0 and a negative value.

[0059] Reference Figure 2 , Figure 2 It represents the relationship between each nonlinear stiffness and the arm length of the U-shaped beam, where:

[0060] like Figure 2 As shown in (a), as the length L1 of the U-shaped beam increases, the nonlinear stiffness k of the middle beam increases. 13 It gradually increases and then stabilizes.

[0061] like Figure 2 As shown in (b), as the length L1 of the U-shaped beam increases, the nonlinear stiffness k of the outer beam increases. 23 First increase and then decrease.

[0062] like Figure 2 As shown in (c), as the arm length L1 of the U-shaped beam increases, the total nonlinear stiffness k3 first increases and then decreases, and can be controlled to be positive, negative and zero.

[0063] like Figure 2 As shown in (d), increasing the initial linear stiffness k of the middle beam and the outer beam 21初 and k 11初 The ratio of k 3最大 , a larger positive value of k3 is obtained, and the value of k3 increases overall. Reduce the initial linear stiffness k of the middle beam and the outer beam 21初 and k 11初The ratio can reduce the negative value of k3, obtain a smaller negative value of k3, and the overall value of k3 is reduced.

[0064] See also Figure 3 Based on this method, an embodiment of the present invention also discloses a MEMS torsion beam, including a middle beam 3, and an outer beam 4 is distributed around the periphery of the middle beam 3; the outer beam 4 includes a side beam 2, and the side beams 2 are parallel and symmetrically distributed on both sides of the middle beam 3, one end of the side beam 2 is connected to a U-shaped beam 1, and the U-shaped beam 1 is connected to the end close to the middle beam 3.

[0065] See also Figure 4 Furthermore, this embodiment also discloses another structure of a MEMS torsion beam, wherein the MEMS multi-fold torsion beam comprises a middle beam arranged along a torsion axis, a plurality of side beams symmetrically arranged about the middle beam, and a U-shaped beam connecting the torsion beam and the side beams. The middle beam and the side beams are arranged in parallel, and the "two arms" of the U-shaped beam are respectively connected to the ends of the middle beam and the side beam, and the U-shaped beam and the side beam together form an outer side beam.

[0066] See also Figure 5 In the torsional MEMS device, the MEMS multi-fold torsion beams are symmetrically arranged on both sides of the torsion motion component, and the moment of inertia of the torsion motion component about the torsion axis is balanced about the torsion axis. The free end of the middle beam is connected to the torsion motion component, and the free end of the side beam serves as a fixed anchor point of the multi-fold torsion beam.

[0067] Based on the above method, the present invention also discloses two specific embodiments:

[0068] Example 1

[0069] Figure 6 It represents an electromagnetically driven MEMS micromirror with a multi-fold torsion beam. The multi-fold torsion beam is symmetrically distributed on both sides of the mirror along the torsion axis. The permanent magnet is arranged directly below the mirror. By applying an alternating electromagnetic field around the permanent magnet, a linear alternating torque is applied to the mirror to achieve the resonant motion of the MEMS micromirror. The nonlinearity of the micromirror is determined by the nonlinearity of the torsion beam. The nonlinearity of the torsion beam is adjusted to near zero to weaken or eliminate the nonlinearity of the micromirror. The specific method is as follows:

[0070] Step 1: From the initial linear stiffness k 1初 =5.499×10 -4 N·m / rad -1 , calculate the initial stiffness of the middle beam and the outer beam, k 11初 ≈1.67*k 1初 =9.1833×10 -4 N·m / rad -1 , k 21初 =2.5*k 1初 =1.3747×10-3 N·m / rad -1 ;

[0071] Step 2: Design the multi-fold torsion beam so that the arm length L1 of the U-shaped beam is minimized and the stiffness of the middle beam and the outer beam are k 11 =9.013×10 -4 N·m / rad -1 and k 21 =1.411×10 -3 N·m / rad -1 At this time, the initial nonlinear stiffness k of the middle beam is 13初 =1.35×10 -6 N·m / rad -3 , the initial nonlinear stiffness k of the outer beam 23初 =-1.16×10 -5 N·m / rad -3 , the total initial nonlinear stiffness k 3初 =-8.36×10 -8 N·m / rad -3 ;

[0072] Step 3: Increase the arm length L1 of the U-shaped beam and reduce the nonlinear stiffness k of the middle beam. 13初 Adjusted to 1.66×10 -6 N·m / rad -3 , the nonlinear stiffness k of the outer beam 23初 Adjusted to -6.18×10 -6 N·m / rad -3 , the total nonlinear stiffness k3 is adjusted to 2.22×10 -8 N·m / rad -3 The absolute value of the nonlinear stiffness of the micromirror is reduced by 4 times, and the nonlinearity is significantly weakened.

[0073] Example 2

[0074] Figure 7 It represents an electrostatically driven MEMS micromirror with a multi-fold torsion beam. The multi-fold torsion beam is symmetrically distributed on both sides of the mirror along the torsion axis, and the comb driver is symmetrically distributed on the other two sides of the mirror. By applying an alternating voltage signal to the static comb teeth and the dynamic comb teeth, an alternating torque is applied to the mirror to achieve the resonant motion of the MEMS micromirror. The nonlinearity of the micromirror is dominated by the nonlinearity of the driving torque. The nonlinearity of the torsion beam is adjusted to the opposite property to offset the nonlinearity of the driving force, so as to weaken or eliminate the nonlinearity of the micromirror. The specific method is as follows:

[0075] Step 1: Determine the nonlinear stiffness k from the driving torque 3e =-1.13×10 -7 N·m / rad -3It can be seen that the total nonlinear stiffness k3 of the torsion beam needs to be adjusted to 1.13×10 -7 N·m / rad -3 nearby;

[0076] Step 2: From the initial linear stiffness k 1初 =5.499×10 -4 N·m / rad -1 , calculate the initial stiffness of the middle beam and the outer beam, k 11初 ≈1.67*k 1初 =9.1833×10 -4 N·m / rad -1 , k 21初 =2.5*k 1初 =1.3747×10 -3 N·m / rad -1 ;

[0077] Step 3: Design the multi-fold torsion beam so that the arm length L1 of the U-shaped beam is minimized and the stiffness of the middle beam and the outer beam are k 11 =9.013×10 -4 N·m / rad -1 and k 21 =1.411×10 -3 N·m / rad -1 At this time, the initial nonlinear stiffness k of the middle beam is 13初 =1.35×10 -6 N·m / rad -3 , the initial nonlinear stiffness k of the outer beam 23初 =-1.16×10 -5 N·m / rad -3 , the total initial nonlinear stiffness k 3初 =-8.36×10 -8 N·m / rad -3 ;

[0078] Step 4: Increase the arm length L1 of the U-shaped beam and reduce the nonlinear stiffness k of the middle beam. 13初 Adjusted to 1.61×10 -6 N·m / rad -3 , the nonlinear stiffness k of the outer beam 23初 Adjusted to -3.46×10 -6 N·m / rad -3 , the total nonlinear stiffness k3 is adjusted to 1.02×10 -7 N·m / rad -3 The nonlinear stiffness of the micromirror is then adjusted to 1.1×10 -8 N·m / rad -3, the absolute value is reduced by 10 times, and the nonlinearity is significantly weakened.

[0079] This method can achieve the purpose of weakening or eliminating the nonlinearity of the MEMS torsion device by regulating the nonlinear stiffness of the MEMS multi-fold torsion beam, independently adjust the stiffness of the MEMS multi-fold torsion beam, is not restricted by the driving form, weakens or eliminates the nonlinearity of the MEMS torsion device, and has a wide range of applications.

[0080] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for controlling the nonlinearity of a MEMS torsion beam, characterized in that: The following steps are involved: According to the initial total linear stiffness of the torsion beam, the initial linear stiffness of the outer beam and the middle beam is given; Given the initial arm length L of the U-shaped beam 1初 ; Based on the given initial linear stiffness of the outer beam and the middle beam, the initial nonlinear stiffness k of the middle beam is obtained: 13初 > 0, the initial nonlinear stiffness k of the outer beam 23初 <0; Control and increase the arm length L1 of the U-shaped beam, so that the nonlinear stiffness of the middle beam begins to increase and is greater than 0, the nonlinear stiffness of the outer beam begins to increase and is less than 0, and the initial total nonlinear stiffness of the torsion beam increases to the maximum peak value; When the total nonlinear stiffness of the torsion beam is at the maximum peak value, the arm length of the U-shaped beam continues to increase. At this time, the nonlinear stiffness of the middle beam continues to increase, the nonlinear stiffness of the outer beam begins to decrease, and the total nonlinear stiffness of the torsion beam begins to gradually decrease.

2. The method for controlling the nonlinearity of a MEMS torsion beam according to claim 1, characterized in that: The initial linear stiffness of the outer beam and the middle beam is given according to the initial total linear stiffness of the torsion beam, including: making k 21初 =1.5*k 11初 , where k 21初 represents the initial linear stiffness of the outer beam, k 11初 represents the initial linear stiffness of the middle beam.

3. The method for controlling the nonlinearity of a MEMS torsion beam according to claim 1, characterized in that: According to the initial total linear stiffness of the torsion beam, when the initial linear stiffness of the outer beam and the middle beam is given, when the ratio of the initial linear stiffness of the outer beam to the initial linear stiffness of the middle beam increases, the maximum peak value of the total nonlinear stiffness of the torsion beam increases; When the ratio of the initial linear stiffness of the outer beam to the middle beam decreases, the maximum peak value of the total nonlinear stiffness of the torsion beam decreases.

4. The method for controlling the nonlinearity of a MEMS torsion beam according to claim 3, characterized in that: When the initial linear stiffness ratio of the outer beam to the middle beam is 2.5, the maximum peak value of the total nonlinear stiffness of the torsion beam is positive.

5. The method for controlling the nonlinearity of a MEMS torsion beam according to claim 4, characterized in that: When the initial linear stiffness ratio of the outer beam and the middle beam is 1, the maximum peak value of the total nonlinear stiffness of the torsion beam is negative.

6. The method for controlling the nonlinearity of a MEMS torsion beam according to claim 1, characterized in that: When the initial total nonlinear stiffness of the torsion beam increases before reaching the maximum peak value, the increasing speed of the nonlinear stiffness of the middle beam is greater than the increasing speed after the total nonlinear stiffness of the torsion beam increases to the maximum peak value.

7. The method for controlling the nonlinearity of a MEMS torsion beam according to claim 1, characterized in that: Increasing the initial total nonlinear stiffness of the torsion beam to the maximum peak value includes the following steps: Increase the arm length L1 of the U-shaped beam, and the nonlinear stiffness k of the middle beam 13 Increase, and k 13 >0; nonlinear stiffness k of the outer beam 23 Increases, and the nonlinear stiffness k 23 <0; the total nonlinear stiffness k3 increases until it reaches 0, the nonlinearity decreases, and the total nonlinear stiffness k3 is 3初 Regulate between 0 and 0; Continue to increase the arm length L1 of the U-shaped beam, the nonlinear stiffness k of the middle beam 13 Increase, the nonlinear stiffness k of the outer beam 23 Increases to the maximum peak value, nonlinearity increases, and the total nonlinear stiffness k3 is between 0 and k 3最大 Between regulation.

8. The method for controlling the nonlinearity of a MEMS torsion beam according to claim 1, characterized in that: The control process of gradually reducing the total nonlinear stiffness of the torsion beam to a negative value includes: When the total nonlinear stiffness of the torsion beam is at its maximum peak, the arm length L1 of the U-shaped beam is further increased, and the nonlinear stiffness k of the middle beam is 13 Continue to increase, and the nonlinear stiffness k 13 >0; nonlinear stiffness k of the outer beam 23 Reduced, and the nonlinear stiffness k 23 <0; the total nonlinear stiffness k3 is reduced to 0, and the nonlinearity is reduced. At this time, the nonlinear stiffness k3 is k 3最大 Regulate between 0 and 0; Continue to increase the arm length L1 of the U-shaped beam, the nonlinear stiffness k of the middle beam 13 Continue to increase, the nonlinear stiffness k of the outer beam 23 Continue to decrease, and k 23 <0, the total nonlinear stiffness k3 is reduced to a negative value, and the nonlinearity increases. At this time, the nonlinear stiffness k3 is regulated between 0 and a negative value.

9. A MEMS torsion beam, characterized in that: The preparation is regulated based on the method according to claim 1.

10. The MEMS torsion beam according to claim 9, characterized in that: It comprises a middle beam, and outer beams are distributed around the periphery of the middle beam; The outer side beams include side beams and U-shaped beams. The side beams are parallel and symmetrically distributed on both sides of the middle beam. One end of the side beam is connected to the U-shaped beam, and the U-shaped beam is connected to the end close to the middle beam.

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