Large-deflection cantilever beam actuating structure

Abstract

A large-deflection cantilever beam actuating structure disclosed by the present invention comprises an actuating module, a reflector and a supporting module, the reflector is fixedly installed at the upper end of the supporting module, and a driving element is arranged on the actuating module. The actuating module comprises a twisting plate fixedly connected with the supporting module and a plurality of actuators connected with the twisting plate, and the driving ends, connected with the twisting plate, of the actuators are asymmetrically arranged on the two sides of a rotating shaft L of the twisting plate. By means of the mode, the large-angle deflection can be achieved, meanwhile, the large-angle deflection device has the advantages of being small in size, high in integration degree, easy to machine and high in yield, and can be matched with reflectors of different sizes.

Description

Technical Field

[0001] The present invention relates to the field of MEMS micromirror structures, and in particular to a large-deflection cantilever beam actuating structure. Background Art

[0002] MEMS micromirrors are MEMS optical devices that are manufactured using MEMS technology and control the deflection of a reflector through an actuator module. They have become a mainstream component in the field of microelectronics. MEMS micromirrors are micro-optical electromechanical systems that integrate materials science, mechanics, electromagnetics, and optics. Compared with traditional mechanical galvanometers, they have the advantages of small size, light weight, low cost, mass production, low power consumption, and high scanning frequency. Currently, MEMS scanning mirrors are mainly used in laser projection [1], virtual reality (VR) near-eye display [2-4], augmented reality (AR) near-eye display [5,6], MEMS three-dimensional imaging lidar [7-11], automotive head-up display (HUD) [12-14], optical communication

[14] , optical coherence tomography (OCT) [16-18], and confocal microscopy [19-21], and they meet the requirements of smartphones, tablets, and wearable devices.

[0003] Micromirrors can be categorized by their operating mode into resonant and quasi-static types. The resonant mode operates at a resonant frequency, utilizing the resonance effect to amplify the amplitude to achieve a large scanning angle. This scanning mode has been the subject of extensive research. Quasi-static micromirrors transition from one static state to another. This state is characterized by a linear relationship between the mirror's deflection angle and the applied voltage, and the deflection angle can be precisely controlled by controlling the applied voltage. In recent years, a growing number of research institutes, both domestically and internationally, have invested in the development of quasi-static micromirrors for applications requiring precise control of the mirror's deflection angle.

[0004] Resonant micromirrors can achieve good scanning performance by amplifying the deflection angle through resonance, while quasi-static micromirrors need to increase the scanning angle while ensuring a certain operating bandwidth in order to achieve good scanning performance. During the design process, increasing the mechanical deflection angle of the micromirror can be achieved by reducing the torsional stiffness and increasing the torque. The former, combined with a certain flexible structure, will lead to a lower resonant frequency and a smaller operating bandwidth, while the latter requires a larger actuator to achieve, which greatly increases the overall size of the device. Therefore, for piezoelectric quasi-static micromirrors, achieving large-angle deflection while maintaining a small size and ensuring an operating bandwidth that meets application requirements is a huge challenge. Summary of the Invention

[0005] The main technical problem solved by the present invention is to provide a large-deflection cantilever beam actuation structure that can achieve large-angle deflection and has the characteristics of small size, high integration, simple processing, high yield, and can be adapted to reflectors of different sizes.

[0006] A technical solution adopted by the present invention is: a large-deflection cantilever beam actuation structure, comprising an actuation module, a reflector and a support module, wherein the reflector is fixedly mounted on the upper end of the support module, and a driving element is provided on the actuation module, wherein the actuation module comprises a torsion plate fixedly connected to the support module and a plurality of actuators connected to the torsion plate, wherein the driving ends of the plurality of actuators connected to the torsion plate are asymmetrically arranged on both sides of the rotation axis L of the torsion plate. In the specific implementation of the present application, the support module is a column, the end face of the column is smaller than the reflector surface, and reflector surfaces of different sizes can be adapted for different application scenarios to increase the duty cycle; the present application adopts a piezoelectric drive method, which has a simple and compact structure, low drive loss, and is easy to manufacture, effectively reducing the difficulty of control. By applying voltage to the driving element, the torsion plate can be rotated around the rotation axis L through the actuator, thereby realizing the rotation of the reflector. The control is convenient and stable, and the structure has the characteristics of small size, high integration, simple processing and high yield.

[0007] The actuators are provided in two numbers, and the driving ends of the two actuators are asymmetrically arranged on both sides of the torsion plate around the rotation axis L. The asymmetrical arrangement of the driving ends of the two actuators of the present application can ensure that the torsion plate drives the reflector to rotate around the rotation axis L without deviation.

[0008] The upper surface of the reflector is a reflecting surface, the lower surface of the reflector is fixed to the supporting module, and the central axis of the reflector is the same as the central line of the supporting module.

[0009] The actuator is a folded beam structure formed by multiple cantilevers connected in sequence. Adjacent cantilevers are deflected at a preset angle, and a driving element is installed on the lower surface of each cantilever.

[0010] The first-stage cantilevers at the outer ends of the two actuators are respectively applied with opposite-phase voltages to cause the torsion plate to drive the reflector to twist around the rotation axis L. The torsion angle of the reflector is equal to the inclination angle of the tip of the last-stage cantilever at the inner end of the actuator.

[0011] The driving elements installed on each section of the cantilever are connected in series, so that the deflections of the actuating modules are superimposed to achieve large-angle deflection of the reflector.

[0012] The piezoelectric drive element includes a first electrode layer, a piezoelectric material layer, and a second electrode layer that are stacked.

[0013] Modal adjustment structures corresponding to the actuating modules are respectively installed on both sides of the torsion plate along the rotation axis L.

[0014] At least one groove is provided on the upper surface of at least one cantilever. In the specific implementation of the present application, at least one groove can be provided on the upper surface of at least one cantilever according to the needs, or at least one groove can be provided on the upper surface of each cantilever, and the groove can be obtained by etching.

[0015] The outer diameter of the reflector is 1 to 20 μm. The small size of the structure can effectively improve the integration and achieve high resolution.

[0016] The large-deflection cantilever beam actuation structure of the present invention has the beneficial effects of achieving large-angle deflection, having the characteristics of small size, high integration, simple processing, high yield, and being adaptable to reflectors of different sizes. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of an actuating module of a large-deflection cantilever beam actuating structure of the present invention;

[0018] Figure 2 This is a schematic structural diagram of a large-deflection cantilever beam actuating structure of the present invention;

[0019] Figure 3 yes Figure 1 Magnified image of;

[0020] Figure 4 This is a schematic structural diagram of an outer frame of a large-deflection cantilever beam actuating structure according to the present invention;

[0021] Figure 5 This is a distribution diagram of actuator electrodes of a large-deflection cantilever beam actuation structure of the present invention;

[0022] Figure 6 is the first-order vibration mode diagram of the present invention;

[0023] Figure 7 This is the 90V drive displacement diagram of the present invention. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions, and advantages of the present invention more apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. Examples of these preferred embodiments are illustrated in the accompanying drawings. The embodiments of the present invention shown in and described with reference to the accompanying drawings are merely exemplary, and the present invention is not limited to these embodiments.

[0025] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, the accompanying drawings only show structures and / or processing steps closely related to the solutions according to the present invention, while other details that are not closely related to the present invention are omitted.

[0026] Furthermore, in the description of the present invention, terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" indicate positions or relationships based on those shown in the accompanying drawings. These terms are used solely to facilitate and simplify the description of the present invention and are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0027] See also Figures 1-4 According to an embodiment of the present invention, a large-deflection cantilever beam actuation structure includes an actuation module 1, a reflector 2, and a support module 3. The reflector 2 is fixedly mounted on the upper end of the support module 3. A driving element 4 is provided on the actuation module 1. The actuation module 1 includes a torsion plate 11 fixedly connected to the support module 3 and a plurality of actuators 12 connected to the torsion plate. The driving ends 121 of the plurality of actuators 12 connected to the torsion plate 11 are asymmetrically arranged on both sides of the rotation axis L of the torsion plate 11. In a specific implementation of the present application, the support module 3 is a column, the end face of the column is smaller than the reflector surface, and can be adapted to reflectors of different sizes for different application scenarios, thereby increasing the duty cycle. The present application adopts a piezoelectric drive method, which has a simple and compact structure, low drive loss, and is easy to manufacture, effectively reducing the difficulty of control. By applying voltage to the driving element, the torsion plate can be rotated about the rotation axis L through the actuator, thereby realizing the rotation of the reflector. The control is convenient and stable. At the same time, it has the characteristics of small size, high integration, simple processing, and high yield. The driving element of the present application can be a piezoelectric actuator, an electrothermal actuator, an electromagnetic actuator, etc.

[0028] The actuators 12 are provided in two numbers, and the driving ends 121 of the two actuators 12 are asymmetrically arranged on both sides of the torsion plate 11 around the rotation axis L. The asymmetrical arrangement of the driving ends 121 of the two actuators 12 of the present application can ensure that the torsion plate drives the reflector to rotate around the rotation axis L without deviation.

[0029] The upper surface of the reflector 2 is a reflective surface, the lower surface of the reflector 2 is fixed to the support module 3 , and the central axis of the reflector 2 is the same as the central line of the support module.

[0030] The actuator 12 is a folded beam structure formed by a plurality of cantilevers 122 connected in sequence. Adjacent cantilevers 122 are deflected at a preset angle, and a piezoelectric drive element 4 is installed on the lower surface of each cantilever 122. The first-stage cantilever at the outer end of the two actuators applies opposite voltages respectively so that the torsion plate drives the reflector to twist around the rotation axis L. The torsion angle of the reflector is equal to the inclination angle of the tip of the last-stage cantilever at the inner end of the actuator. In the specific implementation of the present application, piezoelectric drive elements are arranged along the path direction of the cantilever. The mechanical deformation of adjacent piezoelectric drive elements is opposite, so that the cantilever arms are deformed and the reflector is deflected. The mechanical deformation of adjacent piezoelectric drive elements is opposite, so that the adjacent piezoelectric drive elements will generate driving forces in opposite directions, and the drive arm positions where the adjacent piezoelectric drive elements are located will generate opposite deformations, thereby controlling the lateral offset of the reflector, so that the lateral offset of the center position of the reflector can be kept as small as possible while the reflector is deflected and tilted. Furthermore, the cantilever is provided with multiple piezoelectric drive elements spaced along its length, enabling the cantilever to deform in sections as desired, thereby making the deformation of the drive arm more precisely controllable, and ultimately achieving higher precision in controlling the opposite deflection and tilt of the reflector. Furthermore, each set of cantilevers in the present application has the same length and the same effective length.

[0031] The piezoelectric driving elements installed on each section of the cantilever are connected in series, so that the deflections of the actuating modules are superimposed to achieve large-angle deflection of the reflector.

[0032] The piezoelectric drive element includes a first electrode layer, a piezoelectric material layer, and a second electrode layer that are stacked.

[0033] Modal adjustment structures corresponding to the actuating module are respectively installed on both sides of the torsion plate along the rotation axis L. The modal adjustment structure can be used to adjust the central axis position of the mirror deflection to match the requirements of the optical axis in different applications.

[0034] At least one groove 13 is provided on the upper surface of at least one cantilever. In the specific implementation of the present application, at least one groove can be provided on the upper surface of at least one cantilever according to the requirements, or at least one groove can be provided on the upper surface of each cantilever. The groove can be obtained by etching. The groove is provided on the upper surface of the cantilever of the present application, which can increase the deformation of the cantilever, thereby

[0035] The outer diameter of the reflector is 1 to 20 mm. The structure adopts a double-layer stacking architecture, hiding the actuation structure under the mirror surface. The overall size of the device is small, which can effectively improve the integration and achieve a high duty cycle.

[0036] The actuator module is surrounded by an outer frame 5, and the outer ends of the two actuators are fixedly connected to the outer frame. In the specific implementation of this application, the surface of the reflector 1 is circular, which can be square or rectangular. Of course, the reflector 1 can also adopt other shapes, such as elliptical. Similarly, the outer frame is not limited to rectangular, and can also be circular.

[0037] See Figure 5 In this application, fixed constraints are applied to both ends of the two actuators. The first-order natural frequency is calculated to be 117Hz using the characteristic frequency study. The first-order vibration shape is as follows: Figure 5 shown.

[0038] Apply +90V and -90V voltages to the two actuators respectively, and the displacement diagram is as follows Figure 6 As shown, the maximum displacement of the reflector is 311um, and the calculated half-mechanical angle of the reflector deflection is 7°, which achieves the design goal.

[0039] In addition, it should be noted that, in this specification, "comprises," "includes," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0040] It should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A large deflection cantilever beam actuation structure, characterized in that: It includes an actuating module, a reflector and a supporting module. The reflector is fixedly mounted on the upper end of the supporting module. A driving element is provided on the actuating module. The actuating module includes a torsion plate fixedly connected to the supporting module and multiple actuators connected to the torsion plate. The driving ends of the multiple actuators connected to the torsion plate are asymmetrically arranged on both sides of the rotation axis L of the torsion plate.

2. A large deflection cantilever beam actuating structure according to claim 1, characterized in that: The number of the actuators is two, and the driving ends of the two actuators are asymmetrically arranged on both sides of the rotation axis L of the torsion plate.

3. The large deflection cantilever beam actuating structure according to claim 1, characterized in that: The upper surface of the reflector is a reflecting surface, the lower surface of the reflector is fixed to the supporting module, and the central axis of the reflector is the same as the central line of the supporting module.

4. The large deflection cantilever beam actuating structure according to claim 2, characterized in that: The actuator is a folded beam structure formed by multiple cantilevers connected in sequence. Adjacent cantilevers are deflected at a preset angle, and a driving element is installed on the lower surface of each cantilever.

5. The large deflection cantilever beam actuating structure according to claim 4, characterized in that: The first-stage cantilevers at the outer ends of the two actuators are respectively applied with opposite-phase voltages to cause the torsion plate to drive the reflector to twist around the rotation axis L. The torsion angle of the reflector is equal to the inclination angle of the tip of the last-stage cantilever at the inner end of the actuator.

6. The large deflection cantilever beam actuating structure according to claim 4, characterized in that: The driving elements installed on each section of the cantilever are connected in series, so that the deflections of the actuating modules are superimposed to achieve large-angle deflection of the reflector.

7. The large deflection cantilever beam actuating structure according to claim 6, characterized in that: The pressure-driven element includes a first electrode layer, a driving material layer, and a second electrode layer that are stacked.

8. The large deflection cantilever beam actuating structure according to claim 2, characterized in that: Modal adjustment structures corresponding to the actuating modules are respectively installed on both sides of the torsion plate along the rotation axis L.

9. The large deflection cantilever beam actuating structure according to claim 4, characterized in that: At least one groove is formed on the upper surface of at least one level of the cantilever.

10. The large deflection cantilever beam actuating structure according to claim 1, characterized in that: The outer diameter of the reflector is 1 to 20 μm.

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