Large-deflection cantilever beam actuating structure

Abstract

A large-deflection cantilever beam actuating structure disclosed by the present invention comprises a reflector (1), a supporting module (2) and an actuating module (3), the reflector (1) is fixedly installed at the upper end of the supporting module (2), and the actuating module (3) comprises an inner actuating assembly (31) enabling the reflector (1) to rotate around a rotating shaft Y and an outer actuating assembly (32) enabling the reflector (1) to rotate around a rotating shaft X, a driving element (33) is arranged on the actuating module (3), when the structure is not actuated, the rotating shaft Y and the rotating shaft X are located on the same plane and are perpendicularly arranged, and the supporting module (2) is installed at the intersection position of the rotating shaft Y and the rotating shaft X of the actuating module (3). By means of the mode, the large-angle deflection device adopts double shafts without mutual interference, can achieve large-angle deflection, has the advantages of being small in size, high in integration degree and high in finished product rate, and can be matched with reflectors of different sizes.

Description

Technical Field

[0001] The present invention relates to the technical field of MEMS micromirror preparation, 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, which can adopt a dual-axis decoupling design, and the inner and outer axes do not interfere with each other, and both can achieve large-angle deflection. At the same time, it has the characteristics of small size, high integration, simple processing, and 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, characterized in that it includes a reflector, a support module and an actuation module, the reflector is fixedly mounted on the upper end of the support module, the actuation module includes an internal actuation component that rotates the reflector around a rotation axis Y and an external actuation component that rotates the reflector around a rotation axis X, the actuation module is provided with a driving element, when the structure is not actuated, the rotation axis Y and the rotation axis X are in the same plane and are arranged vertically, and the support module is installed at the intersection of the rotation axis Y and the rotation axis X of the actuation module. In the specific implementation of this application, the support module is a column, the end face of the column is smaller than the reflector, and reflector surfaces of different sizes can be adapted for different application scenarios to increase the duty cycle; this application adopts a piezoelectric drive method, which has a simple structure, good compactness, low drive loss, and is easy to manufacture, effectively reducing the difficulty of control. By applying voltage to the drive element, the torsion plate and the inner frame can be rotated separately through the internal and external actuating components, thereby achieving the reflector without interfering with each other when rotating around the rotation axis Y and the rotation axis X, and both can achieve large-angle deflection, easy control, good stability, and at the same time have the characteristics of small size, high integration, simple processing, and high yield.

[0007] The internal actuating assembly includes a torsion plate, a first driving arm and a second driving arm. The driving ends of the first driving arm and the second driving arm are asymmetrically connected to the two sides of the torsion plate and are arranged on both sides of the rotation axis Y. The fixed ends of the first driving arm and the second driving arm are connected to an inner frame, and the driving end of the external actuating assembly is asymmetrically connected to the inner frame.

[0008] The external actuating assembly includes a third driving arm and a fourth driving arm, and the connection points where the driving ends of the third driving arm and the fourth driving arm are connected to the inner frame are located on both sides of the rotation axis X.

[0009] The first driving arm, the second driving arm, the third driving arm and the fourth driving arm are all folded beam structures formed by multiple stages of 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 multi-stage cantilevers of the first driving arm and the second driving arm are formed by driving elements spaced apart from the first-stage cantilever of the first driving arm to form a first actuator, the multi-stage cantilevers of the first driving arm and the second driving arm are formed by driving elements spaced apart from the first-stage cantilever of the second driving arm to form a second actuator, the multi-stage cantilevers of the third driving arm and the fourth driving arm are formed by driving elements spaced apart from the first-stage cantilever of the third driving arm to form a third actuator, and the multi-stage cantilevers of the third driving arm and the fourth driving arm are formed by driving elements spaced apart from the first-stage cantilever of the fourth driving arm to form a fourth actuator. The first-stage cantilevers of the first actuator and the second actuator are respectively applied with opposite-phase voltages to rotate the torsion plate, and the first-stage cantilevers of the third actuator and the fourth actuator are respectively applied with opposite-phase voltages to rotate the inner frame. 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 first actuator and the second actuator, and the torsion angle of the reflector is equal to the inclination angle of the tip of the inner frame.

[0011] The driving elements installed on each stage 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 third actuator and the fourth actuator are respectively installed on both sides of the inner frame along the rotation axis X.

[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 mm.

[0016] The beneficial effects of the large-deflection cantilever beam actuation structure of the present invention are: it can adopt a dual-axis decoupling design, the inner and outer axes do not interfere with each other, and both can achieve large-angle deflection. At the same time, it has the characteristics of small size, high integration, simple processing, and high yield, and can be adapted to reflectors of different sizes. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a top view 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 2 Magnified image of;

[0020] Figure 4 This is a distribution diagram of actuator electrodes of a large-deflection cantilever beam actuation structure of the present invention;

[0021] Figure 5 is the first-order vibration mode diagram of the present invention;

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

[0023] Figure 7 is the third-order vibration mode diagram of the present invention;

[0024] Figure 8 This is the displacement diagram of the rotation axis Y 90V drive of the present invention;

[0025] Figure 9 This is the X 90V driving displacement diagram of the rotation axis of the present invention. DETAILED DESCRIPTION

[0026] 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.

[0027] 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.

[0028] 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.

[0029] See also Figures 1-4An embodiment of the present invention provides a large-deflection cantilever beam actuation structure, comprising a reflector 1, a support module 2, and an actuation module 3. The reflector 1 is fixedly mounted on the upper end of the support module 2. The actuation module 3 comprises an inner actuation assembly 31 for rotating the reflector 1 around a rotation axis Y and an outer actuation assembly 32 for rotating the reflector 1 around a rotation axis X. A driving element 33 is provided on the actuation module 3. When the structure is not actuated, the rotation axis Y and the rotation axis X are coplanar and perpendicular to each other. The support module 2 is mounted at the intersection of the rotation axis Y and the rotation axis X of the actuation module 3. In the specific implementation of this application, the support module is a column, the end face of the column is smaller than the reflective mirror, and can be adapted to reflective mirrors of different sizes for different application scenarios, thereby increasing the duty cycle; this application adopts a piezoelectric drive method, which has a simple structure, good compactness, low drive loss, is easy to manufacture, and effectively reduces the difficulty of control. By applying voltage to the drive element, the internal and external actuator components can be rotated separately, thereby achieving the reflective mirrors not interfering with each other when rotating around the rotation axis Y and the rotation axis X, and both can achieve large-angle deflection, easy control, good stability, and at the same time have the characteristics of small size, high integration, simple processing, and high yield rate. The drive element of this application can be a piezoelectric actuator, an electrothermal actuator, an electromagnetic actuator, etc.

[0030] The inner actuating assembly 31 includes a torsion plate 311, a first actuating arm 312, and a second actuating arm 313. The driving ends of the first actuating arm 312 and the second actuating arm 313 are asymmetrically connected to the sides of the torsion plate 311 and are disposed on either side of the rotation axis Y. The fixed ends of the first actuating arm 312 and the second actuating arm 313 are connected to an inner frame 314. The driving end of the outer actuating assembly 32 is asymmetrically connected to the inner frame 314. The outer actuating assembly 32 includes a third actuating arm 321 and a fourth actuating arm 322. The connection points between the driving ends of the third actuating arm 321 and the fourth actuating arm 322 and the inner frame 314 are located on either side of the rotation axis X.

[0031] The upper surface of the reflector 1 is a reflective surface, the lower surface of the reflector 1 is fixed to the support module 2 , and the central axis of the reflector 1 is the same as the central line of the support module.

[0032] The first driving arm 312, the second driving arm 313, the third driving arm 321 and the fourth driving arm 322 are all folded beam structures formed by multiple stages of cantilevers connected in sequence. The adjacent cantilevers are deflected by a preset angle, and a piezoelectric driving element 33 is installed on the lower surface of each cantilever.

[0033] The multi-stage cantilevers of the first driving arm 312 and the second driving arm 313 are formed by piezoelectric driving elements 33 spaced apart from the first stage cantilever of the first driving arm 312 to form a first actuator. The multi-stage cantilevers of the first driving arm 312 and the second driving arm 313 are formed by piezoelectric driving elements 33 spaced apart from the first stage cantilever of the second driving arm 313 to form a second actuator. The multi-stage cantilevers of the third driving arm 321 and the fourth driving arm 322 are formed by piezoelectric driving elements 33 spaced apart from the first stage cantilever of the third driving arm 321 to form a third actuator. The piezoelectric drive elements 33 spaced apart from the first-stage cantilever of the fourth drive arm 322 and the multi-stage cantilever of the first actuator 21 and the fourth actuator 322 form a fourth actuator. The first-stage cantilever of the first actuator and the second actuator respectively apply opposite voltages to rotate the torsion plate, and the first-stage cantilever of the third actuator and the fourth actuator respectively apply opposite voltages to rotate the inner frame 314. 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 first actuator and the second actuator, and the torsion angle of the reflector is equal to the inclination angle of the tip of the inner frame 314. The first-stage cantilever of the first actuator and the second actuator respectively applies opposite voltages to cause the torsion plate to drive the reflector to rotate about the rotation axis Y. 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 first actuator and the second actuator. In a specific implementation of the present application, the mechanical deformation of adjacent piezoelectric drive elements 33 is opposite, causing the cantilever arms to deform and thereby drive the reflector to deflect. The mechanical deformations of adjacent piezoelectric drive elements 33 are opposite, so that adjacent piezoelectric drive elements 33 will generate driving forces in opposite directions, causing the drive arm positions where adjacent piezoelectric drive elements 33 are located to produce opposite deformations, thereby controlling the lateral offset of the reflector, so that the lateral offset of the reflector center position can be kept as minimum as possible while the reflector is deflected and tilted. Furthermore, multiple piezoelectric drive elements 33 are spaced apart along the length direction of the multi-stage cantilever of the first actuator and the second actuator, which can enable the cantilever to undergo the required deformation in sections, thereby making the deformation of the drive arm more accurately controllable, and ultimately making the opposite deflection and tilt control of the reflector more accurate. Furthermore, the length of each group of cantilevers in the present application is the same, and their effective lengths are the same. Furthermore, the third actuator and the fourth actuator make the rotation principle of the inner frame 314 the same as the rotation principle of the torsion plate of the first actuator and the second actuator, which will not be repeated here.

[0034] The piezoelectric driving elements 33 installed on each section of the cantilever are connected in series, so that the deflections of the actuating modules are superimposed to achieve a large-angle deflection of the reflector.

[0035] The piezoelectric drive element includes a first electrode layer, a piezoelectric material layer, and a second electrode layer that are stacked.

[0036] Modal adjustment structures corresponding to the third actuator and the fourth actuator are respectively installed on both sides of the inner frame 314 along the rotation axis X. The central axis position of the mirror deflection can be adjusted through the modal adjustment structure to match the requirements of the optical axis in different applications.

[0037] At least one groove 13 is formed on the upper surface of at least one cantilever stage. In specific implementations of the present invention, at least one groove can be provided on the upper surface of at least one cantilever stage, or at least one groove can be provided on the upper surface of each cantilever stage. The grooves can be formed by etching. The grooves provided on the upper surface of the cantilever of the present invention can increase the deformation of the cantilever.

[0038] The outer diameter of the reflector is 1 to 20 mm. The structure adopts a double-layer stacked 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 in the dual-axis drive device.

[0039] In the specific implementation of this application, the surface of the reflector 1 is circular, which can be a square or a rectangle. Of course, the reflector 1 can also adopt other shapes, such as an ellipse. Similarly, the outer frame is not limited to a rectangle, and can also be circular.

[0040] This application applies fixed constraints to the ends of the first-stage cantilevers of the third and fourth actuators, and calculates the first-order natural frequency to be 136 Hz, the second-order natural frequency to be 145 Hz, and the third-order natural frequency to be 196 Hz using characteristic frequency research. Figure 5 The Piston mode is shown, and the second-order vibration shape is as follows Figure 6 is the external shaft torsional mode, and the third-order vibration shape is as follows Figure 7 is the inner shaft torsional mode.

[0041] Scanning angle simulation: First, apply +90V and -90V voltages to the ends of the first-stage cantilever of the third actuator and the fourth actuator respectively. The displacement diagram is shown in the figure below. Figure 8 As shown, the calculated half-mechanical angle of the mirror deflection around the rotation axis X is 3.4°.

[0042] Apply +90V and -90V voltages to the first stage cantilever of the first actuator and the second actuator respectively. The displacement diagram is shown in Figure 9 As shown, the calculated semi-mechanical angle of the reflector deflection around the rotation axis Y is 3.5°. This application adopts a dual-axis decoupling design so that the reflector does not interfere with each other when deflecting around the rotation axis Y and the rotation axis X, and both can achieve large-angle deflection.

[0043] 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.

[0044] 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: The invention comprises a reflector (1), a support module (2) and an actuating module (3), wherein the reflector (1) is fixedly mounted on the upper end of the support module (2), the actuating module (3) comprises an inner actuating assembly (31) for rotating the reflector (1) around a rotation axis Y and an outer actuating assembly (32) for rotating the reflector (1) around a rotation axis X, the actuating module (3) is provided with a driving element (33), and when the structure is not actuated, the rotation axis Y and the rotation axis X are in the same plane and are arranged vertically, and the support module (2) is mounted at the intersection of the rotation axis Y and the rotation axis X of the actuating module (3).

2. A large deflection cantilever beam actuating structure according to claim 1, characterized in that: The inner actuating assembly (31) includes a torsion plate (311), a first driving arm (312) and a second driving arm (313), wherein the driving ends of the first driving arm (312) and the second driving arm (313) are asymmetrically connected to the two sides of the torsion plate (311) and are arranged on both sides of the rotation axis Y, and the fixed ends of the first driving arm (312) and the second driving arm (313) are connected to an inner frame (314), and the driving end of the outer actuating assembly (32) is asymmetrically connected to the inner frame (314).

3. A large deflection cantilever beam actuating structure according to claim 2, characterized in that: The external actuating assembly (32) includes a third driving arm (321) and a fourth driving arm (322), and the connection points where the driving ends of the third driving arm (321) and the fourth driving arm (322) are connected to the inner frame (314) are located on both sides of the rotation axis X.

4. A large deflection cantilever beam actuating structure according to claim 3, characterized in that: The first driving arm (312), the second driving arm (313), the third driving arm (321) and the fourth driving arm (322) are all folded beam structures formed by multiple stages of cantilever arms connected in sequence, with adjacent cantilever arms deflected at a preset angle, and a driving element (33) is installed on the lower surface of each cantilever segment.

5. The large deflection cantilever beam actuating structure according to claim 4, characterized in that: The multi-stage cantilever of the first driving arm (312) and the second driving arm (313) is formed by a driving element (33) spaced apart from the first stage cantilever of the first driving arm (312) to form a first actuator, the multi-stage cantilever of the first driving arm (312) and the second driving arm (313) is formed by a driving element (33) spaced apart from the first stage cantilever of the second driving arm (313) to form a second actuator, the multi-stage cantilever of the third driving arm (321) and the fourth driving arm (322) is formed by a driving element (33) spaced apart from the first stage cantilever of the third driving arm (321) to form a third actuator, the third driving arm (321) ) and the multi-stage cantilever of the fourth driving arm (322) are spaced apart from the first stage cantilever of the fourth driving arm (322) to form a fourth actuator, the first stage cantilever of the first actuator and the second actuator respectively applies an anti-phase voltage to rotate the torsion plate (311), the first stage cantilever of the third actuator and the fourth actuator respectively applies an anti-phase voltage to rotate the inner frame (314), the torsion angle of the reflector (1) is equal to the inclination angle of the tip of the last stage cantilever at the inner end of the first actuator and the second actuator, and the torsion angle of the reflector (1) is equal to the inclination angle of the tip of the inner frame (314).

6. The large deflection cantilever beam actuating structure according to claim 5, characterized in that: The driving elements (33) installed on each stage of the cantilever are connected in series, so that the deflections of the actuating modules are superimposed, thereby achieving a large-angle deflection of the reflector (1).

7. The large deflection cantilever beam actuating structure according to claim 6, characterized in that: The pressure-driven element (33) comprises a first electrode layer, a driving material layer, and a second electrode layer which are stacked.

8. The large deflection cantilever beam actuating structure according to claim 2, characterized in that: Modal adjustment structures corresponding to the third actuator and the fourth actuator are respectively installed on both sides of the inner frame (314) along the rotation axis X.

9. The large deflection cantilever beam actuating structure according to claim 4, characterized in that: At least one groove (34) is formed on the upper surface of at least one cantilever.

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

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