CN111965811A - Three-dimensional MEMS scanning mirror - Google Patents

Abstract

The three-dimensional MEMS scanning mirror provided by the present invention is applied to the technical field of micro-electromechanical systems, and includes a lens and a two-dimensional scanning mechanism, the lens includes a lens body and an electrically controlled deformation layer, and the electrically controlled deformation layer covers a preset area on the lens body, And the control end of the electronically controlled deformation layer is connected with the control power supply, and according to the received current or voltage, the electronically controlled deformation layer can drive the lens body to produce off-surface displacement. In actual use, by controlling the power supply to output different currents or voltages, the electronically controlled deformation layer is controlled to drive the lens body to produce off-plane displacement, thereby changing the curvature of the mirror surface, adjusting the focal length, and supplemented by a two-dimensional scanning mechanism to achieve three-dimensional scanning. Therefore, the scanning mirror lens provided by the present invention can change the curvature of the mirror surface without relying on the cavity in the existing lens structure, thereby reducing the processing difficulty and processing cost of the lens.

Description

A three-dimensional MEMS scanning mirror

technical field

The invention belongs to the technical field of micro-electromechanical systems, and in particular relates to a three-dimensional MEMS scanning mirror.

Background technique

The scanning mirror based on MEMS (Micro-Electro-Mechanical System, Micro-Electro-Mechanical System) technology, namely MEMS scanning mirror, can realize precise control and positioning of the laser beam direction, and also has the advantages of small size, fast angle conversion speed, low cost, etc. Therefore, it has broad application prospects in projection display, lidar, laser processing, free space optical communication and many other aspects.

In practical applications, two-dimensional scanning can be achieved by controlling the rotation of the lens around two rotating axes that are in a vertical relationship. Scanning in the axial direction realizes three-dimensional scanning.

Referring to FIG. 1, FIG. 1 shows a lens structure of a three-dimensional MEMS scanning mirror. The lens is provided with a cavity, and can be divided into an upper-layer lens and a lower-layer lens with the cavity as a boundary. Among them, the upper lens is provided with an upper electrode, and a lower electrode is placed in the cavity. After the upper electrode and the lower electrode are energized, electrostatic attraction will be generated between the two, so that the upper lens is driven by the upper electrode to have an off-surface displacement, thereby changing the mirror surface. curvature. In this process, the cavity not only plays the role of accommodating the lower electrode and ensuring the normal occurrence of electrostatic attraction, but also the depth of the cavity determines the range of the upper lens's off-surface displacement, that is, the adjustment range of the lens' focal length.

Most of the cavities in the lens structure shown in Figure 1 are obtained in two ways. One is to splice multiple lenses by wafer bonding, and the other is to etch the lenses by wet etching. Whichever method is adopted, there are problems of high processing difficulty and high cost. In addition, the method of wet etching also makes the lens thinner, which reduces its scanning performance index.

SUMMARY OF THE INVENTION

In view of this, the purpose of the present invention is to provide a three-dimensional MEMS scanning mirror, which can change the curvature of the mirror surface without relying on the cavity in the existing lens structure, and reduce the processing difficulty and processing cost of the mirror. The specific scheme is as follows:

The present invention provides a three-dimensional MEMS scanning mirror, comprising: a lens and a two-dimensional scanning mechanism, wherein,

The lens is arranged on the two-dimensional scanning mechanism, and the lens includes a lens body and an electronically controlled deformation layer;

the electrically controlled deformation layer covers a preset area of the lens body;

The control end of the electrically controlled deformation layer is connected to a control power supply, and the electrically controlled deformation layer is used to drive the lens body to generate off-plane displacement according to the received current or voltage, so as to change the curvature of the mirror surface.

Optionally, the electrically controlled deformation layer includes a metal thin film, and the thermal expansion coefficient of the metal thin film is different from the thermal expansion coefficient of the lens body.

Optionally, the electrically controlled deformation layer includes a piezoelectric thin film.

Optionally, the thermal expansion coefficient of the metal film is greater than the thermal expansion coefficient of the lens body.

Optionally, the piezoelectric film includes a first electrode plate, a second electrode plate and a piezoelectric material layer, wherein,

the piezoelectric material layer is disposed between the first electrode plate and the second electrode plate;

The input ends of the first electrode plate and the second electrode plate are respectively connected with the control power supply.

Optionally, the center of the preset area coincides with the center of the mirror surface of the lens body.

Optionally, the electrically controlled deformation layer is deposited on the surface of the lens body.

Optionally, the two-dimensional scanning mechanism includes a first frame and a second frame, wherein,

the first frame is rotatable around the first rotation axis;

the second frame is connected with the first frame, and the second frame can rotate around a second rotation axis;

The axis of the first rotating shaft intersects perpendicularly with the axis of the second rotating shaft;

The lens is arranged on the second frame.

Optionally, the lens and the second frame are connected by a flexible connector.

Optionally, if the lens is circular and the second frame is a circular frame, the flexible connector is a fan-shaped flexible connector with the center of the lens as the center of the circle.

The three-dimensional MEMS scanning mirror provided by the present invention includes a lens and a two-dimensional scanning mechanism, the lens is arranged on the two-dimensional scanning mechanism, and the lens includes a lens body and an electronically controlled deformation layer, and the electronically controlled deformation layer covers a preset area on the lens body, And the control end of the electronically controlled deformation layer is connected with the control power supply, and according to the received current or voltage, the electronically controlled deformation layer can drive the lens body to produce off-surface displacement. In actual use, by controlling the power supply to output different currents or voltages, controlling the electronically controlled deformation layer to drive the lens body to produce off-plane displacement, thereby changing the mirror curvature, adjusting the focal length, and cooperating with the two-dimensional scanning mechanism to achieve three-dimensional scanning. Therefore, the lens provided by the present invention can change the curvature of the mirror surface without relying on the cavity in the existing lens structure, the process is simpler, and the processing difficulty and processing cost of the lens are reduced.

Further, in the scanning mirror provided by the present invention, since the lens is no longer limited by the cavity of the lens in the prior art, the out-of-plane displacement that the lens can produce is completely determined by the deformation range of the electronically controlled deformation layer and the characteristics of the lens itself, which is different from the existing lens. Compared with the existing technology, the adjustment range of the focal length of the lens can be greatly improved.

Description of drawings

In order to illustrate the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are For some embodiments of the present invention, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

1 is a schematic diagram of the lens structure of a three-dimensional MEMS scanning mirror in the prior art;

2 is a schematic structural diagram of a scanning mirror provided by an embodiment of the present invention;

3 is a schematic structural diagram of a lens provided by an embodiment of the present invention;

4 is a schematic diagram of a deformation effect of a lens provided by an embodiment of the present invention;

5 is a schematic structural diagram of another lens provided by an embodiment of the present invention;

Fig. 6 is the realization principle schematic diagram of two-dimensional scanning in the prior art;

FIG. 7 is a schematic diagram of the implementation principle of three-dimensional scanning in the prior art.

Detailed ways

In order to make the purposes, 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 with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Optionally, referring to FIG. 2, FIG. 2 is a schematic structural diagram of a three-dimensional MEMS scanning mirror provided by an embodiment of the present invention. The three-dimensional MEMS scanning mirror provided by an embodiment of the present invention includes: a lens 300 and a two-dimensional scanning mechanism (in the figure The first frame 100 and the second frame 200 of the two-dimensional scanning mechanism are shown), and the lens 300 is arranged on the two-dimensional scanning mechanism. Specifically,

The first frame 100 in the two-dimensional scanning mechanism can rotate around the first rotation axis;

The second frame 200 is connected to the first frame 100 , and the second frame 200 is rotatable around the second rotating shaft, and the axis of the first rotating shaft and the axis of the second rotating shaft intersect perpendicularly.

Based on the connection and rotation relationship between the first frame 100 and the second frame 200, the two-dimensional scanning of the laser beam can be realized. Of course, two-dimensional scanning may also be implemented in other manners in the prior art, which will not be repeated here.

On the basis of the above frame structure, the lens 300 is specifically arranged on the second frame. Optionally, referring to FIG. 3 , FIG. 3 is a schematic structural diagram of a lens provided by an embodiment of the present invention. The lens provided by an embodiment of the present invention includes: an electrically controlled deformation layer 10 and a lens body 20 , wherein,

The electrically controlled deformation layer 10 covers a predetermined area of the lens body 20 , and the electrically controlled deformation layer is deposited on the surface of the lens body 20 . In actual use, the laser beam is adjusted by the mirror of the lens body 20, and the electronically controlled deformation layer 10 is combined with the surface opposite to the mirror surface, which will not have any influence on the normal function of the lens body 20. The deformation control layer 10 drives the lens body 20 to deform.

It is conceivable that, in order to ensure that the electronically controlled deformation layer 10 can reliably drive the lens body 20 to deform together when the electronically controlled deformation layer 10 is displaced, the electronically controlled deformation layer 10 should be tightly and reliably fixed with the lens body 20 to avoid the electronically controlled deformation layer. 10 is separated from the lens body 20 during the deformation process, so that the mirror surface curvature of the lens body 20 cannot be changed.

The control terminal of the electronically controlled deformation layer 10 is connected to a control power source (not shown in the figure), and the control terminal receives the control current or control voltage output by the control power source through the control terminal, and further drives the lens body 20 according to the received current or voltage to generate an off-surface Displacement to change the curvature of the mirror surface of the lens body 20, thereby realizing the adjustment of the focal length of the lens.

Optionally, referring to FIG. 4 , FIG. 4 is a schematic diagram of a deformation effect of a lens provided by an embodiment of the present invention. As can be seen from the figure, after the electronically controlled deformation layer 10 receives the current or voltage of the control power source, an outward expansion stress is generated. Since the electronically controlled deformation layer 10 covers the predetermined area of the lens body 20, the lens body 20 will The deformation of the electronically controlled deformation layer 10 is restrained, and the outward expansion stress is converted into a bending moment of the lens body 20, which drives the lens body 20 to produce off-plane displacement, and realizes the adjustment of the lens curvature.

To sum up, in the 3D MEMS scanning mirror provided by the embodiment of the present invention, the electronically controlled deformation layer of the lens drives the lens body to generate off-plane displacement according to the received control current or control voltage, thereby changing the curvature of the mirror surface and adjusting the focal length. Therefore, the lens provided by the embodiment of the present invention can change the curvature of the mirror surface without relying on the cavity in the existing lens structure, thereby reducing the processing difficulty and processing cost of the lens. Further, since the lens provided by the embodiment of the present invention can realize the adjustment of the mirror surface curvature, the third-dimensional scanning of the laser beam can be realized by adjusting the mirror surface curvature of the lens and cooperating with the two-dimensional scanning mechanism.

Furthermore, in the scanning mirror provided by the present invention, since the lens is no longer limited by the cavity of the lens in the prior art, the off-plane displacement that the lens can produce is completely determined by the deformation range of the electronically controlled deformation layer and the characteristics of the lens itself, which is different from that of the lens itself. Compared with the prior art, the adjustment range of the focal length of the lens can be greatly improved.

Optionally, in order to reduce the influence or restraint caused by the connection part between the lens 300 and the second frame 200 on the out-of-plane displacement of the lens 300, the lens 300 and the second frame 200 are connected by a flexible connecting member 400 to ensure that the lens 300 changes the mirror surface. The external resistance is the least when it is curved.

Optionally, if the lens 300 is circular and the second frame 200 is a circular frame as shown in the example of FIG. 2 , the flexible connecting member between the lens 300 and the second frame 200 is preferably a fan-shaped flexible connecting member 400 . The selection of the fan-shaped flexible connecting frame not only imposes less constraints on the lens 300, but under the same other factors, a larger bending amplitude can be obtained, and the shape of the mirror surface after bending is closer to an ideal paraboloid, thus achieving higher convergence accuracy. Further, by selecting the fan-shaped flexible connecting frame, the gap between the lens and the second frame can be minimized, and the useless area can be reduced to the greatest extent.

Optionally, the electrically controlled deformation layer in the lens provided by the embodiment of the present invention may be formed of a metal thin film. When the electrically controlled deformation layer is formed of a metal thin film, the structure of the lens may refer to the structure given in the example of FIG. 3 , and a schematic diagram of the structure will not be provided separately here.

Further, in order to achieve off-plane displacement of the lens body through the metal film, the thermal expansion coefficient of the metal film is different from that of the lens body. Optionally, a metal with a thermal expansion coefficient greater than that of the lens body can be selected. Based on this, the specific material selection of the metal film should also be selected according to the specific material of the lens body and the thermal expansion coefficient of the lens body. On the premise of not exceeding the scope of the core idea of the present invention, it also falls within the protection scope of the present invention.

As an optional implementation, two pins for connecting the control power supply can be set on the metal film, and the pins are the control terminals of the electrically controlled deformation layer, which connect the two preset pins of the metal film with the control The output end of the power supply is connected and forms a complete current loop with the control power supply. When the control power supply outputs current, the current flows through the metal film, causing the metal film to heat up and deform. At the same time, because the metal film and the lens body are tightly fixed together, and in actual production, the metal film and the lens body are very thin. Therefore, under the action of the heat generated by the metal film, the lens body will also deform.

Due to the different thermal expansion coefficients of the lens body and the metal film, the thermal stress of the two is also different. The bending torque generated under the action of different thermal stresses will cause the lens to produce off-plane displacement, realize the change of the mirror surface curvature, and finally adjust the lens. focal length.

It is conceivable that by adjusting the output current of the control power supply, the thermal stress generated by the metal film can be controlled. The change of thermal stress will naturally drive the lens to produce different distances from the surface. Therefore, by adjusting the output of the control power supply, the The current can be used to adjust the curvature of the mirror surface of the lens provided by the embodiment of the present invention.

Optionally, see FIG. 5 , which is a schematic structural diagram of another lens provided by an embodiment of the present invention. In this embodiment, the electrically controlled deformation layer is formed of a piezoelectric film. Specifically, the piezoelectric film is formed of a first The electrode plate 101, the second electrode plate 103, and the piezoelectric material layer 102 are formed, wherein,

The piezoelectric material layer 102 is arranged between the first electrode plate 101 and the second electrode plate 103, and the input ends of the first electrode plate 101 and the second electrode plate 103 are respectively connected to the control power supply, and form a complete control loop with the control power supply .

It is well known that under the action of an electric field, charged particles in a crystal can be polarized by relative displacement. Under the action of stress, the charged particles in the crystal also undergo relative displacement. For some crystals, the positive and negative charge centers no longer coincide after the relative displacement of the charged particles, so polarization occurs, and bound charges with opposite signs appear on the surfaces at both ends, and there is a linear relationship between the surface charge density and the stress. This effect of surface charge generated by the mechanical stress surface is called the positive piezoelectric effect. When a crystal is subjected to an electric field, strain appears in some directions, and there is a linear correlation between the strain and the field strength. This phenomenon is called the inverse piezoelectric effect.

In the embodiment of the present invention, the piezoelectric material is selected as the electrically controlled deformation layer, which is realized based on the above-mentioned inverse piezoelectric effect. In practical applications, the first electrode plate 101 and the second electrode plate 103 of the piezoelectric film are provided with input terminals, which are connected to the control power supply. By controlling the power supply to adjust the voltage applied to the first electrode plate 101 and the second electrode plate 103, an electric field can be generated in the piezoelectric film. Due to the inverse piezoelectric effect, the piezoelectric film will generate outward expansion stress. The constraining action of the lens body 20 and the stress generated by the inverse piezoelectric effect will generate a bending torque, and finally drive the lens body 20 to undergo an off-plane displacement, thereby realizing the adjustment of the curvature of the mirror surface.

According to the above content and the basic principle of the piezoelectric film, it can be known that by adjusting the voltage value applied to the piezoelectric film output by the control power supply, the stress generated by the piezoelectric film can be changed, thereby realizing the specific control of the curvature of the mirror surface and realizing the focal length of the lens. adjustment.

It should be noted that the piezoelectric films in the prior art that can realize the above-mentioned control principle are all optional, and the application of the present invention does not limit the specific selection of the piezoelectric films.

Optionally, as can be seen from the foregoing content, the electronically controlled deformation layer and the lens body should be tightly and reliably fixed together. Therefore, the combination of the electronically controlled deformation layer and the lens body can be selected by passing the components or materials of the electronically controlled deformation layer through the lens body. For the manner of depositing on the surface of the lens body by physical or chemical means, the specific process may be implemented with reference to the implementation manner in the prior art, which is not specifically limited in the embodiment of the present invention.

Further, in order to ensure that the lens body is uniformly stressed during the process that the electronically controlled deformation layer drives the lens body to produce off-plane displacement, so as to ensure the normal service life of the lens body, therefore, in the above embodiments, the preset area on the lens body is The center of the lens should coincide with the center of the mirror surface of the lens body. In addition, under normal circumstances, the lens body will use a mirror surface with a regular shape, such as a circle or a regular polygon. In this case, the shape of the preset area should preferably be consistent with the shape of the mirror surface. In the case of a circle, the preset area is also set to a circle. The area of the preset area may be equal to or smaller than the mirror surface area, which also belongs to the protection scope of the present invention under the premise of not exceeding the scope of the core idea of the present invention.

Optionally, referring to FIG. 6, FIG. 6 is a schematic diagram of the implementation principle of two-dimensional scanning in the prior art. The scanning process shown in FIG. 6 only shows the effect of one-dimensional scanning, and the other one-dimensional scanning is perpendicular to the paper surface. scans are not shown.

On the basis of the scanning principle shown in Fig. 6, 3D scanning can be realized with the lens with adjustable mirror curvature. For the working principle of 3D scanning, please refer to the embodiment shown in Fig. 7. For the specific control process of 3D scanning, please refer to the present It is realized by the implementation manners in the prior art, and details are not described herein again.

The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the various embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant part can be referred to the description of the method.

Professionals may further realize that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two, in order to clearly illustrate the possibilities of hardware and software. Interchangeability, the above description has generally described the components and steps of each example in terms of function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans may implement the described functionality using different methods for each particular application, but such implementations should not be considered beyond the scope of the present invention.

The steps of a method or algorithm described in connection with the embodiments disclosed herein may be directly implemented in hardware, a software module executed by a processor, or a combination of the two. The software module can be placed in random access memory (RAM), internal memory, read only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other in the technical field. in any other known form of storage medium.

The above description of the disclosed embodiments enables any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the core idea or scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. a three-dimensional MEMS scanning mirror, is characterized in that, comprises: lens and two-dimensional scanning mechanism, wherein, The lens is arranged on the two-dimensional scanning mechanism, and the lens includes a lens body and an electronically controlled deformation layer; the electrically controlled deformation layer covers a preset area of the lens body; The control end of the electrically controlled deformation layer is connected to a control power supply, and the electrically controlled deformation layer is used to drive the lens body to generate off-plane displacement according to the received current or voltage, so as to change the curvature of the mirror surface. 2 . The three-dimensional MEMS scanning mirror according to claim 1 , wherein the electrically controlled deformation layer comprises a metal film, and the thermal expansion coefficient of the metal film is different from that of the lens body. 3 . 3 . The three-dimensional MEMS scanning mirror according to claim 1 , wherein the electrically controlled deformation layer comprises a piezoelectric film. 4 . 4 . The three-dimensional MEMS scanning mirror according to claim 2 , wherein the thermal expansion coefficient of the metal film is greater than the thermal expansion coefficient of the lens body. 5 . 5. The three-dimensional MEMS scanning mirror according to claim 3, wherein the piezoelectric film comprises a first electrode plate, a second electrode plate and a piezoelectric material layer, wherein, the piezoelectric material layer is disposed between the first electrode plate and the second electrode plate; The input ends of the first electrode plate and the second electrode plate are respectively connected with the control power supply. 6 . The three-dimensional MEMS scanning mirror according to claim 1 , wherein the center of the preset area coincides with the center of the mirror surface of the lens body. 7 . 7 . The three-dimensional MEMS scanning mirror according to claim 1 , wherein the electrically controlled deformation layer is deposited on the surface of the lens body. 8 . 8. The three-dimensional MEMS scanning mirror according to claim 1, wherein the two-dimensional scanning mechanism comprises a first frame and a second frame, wherein, the first frame is rotatable around the first rotation axis; the second frame is connected with the first frame, and the second frame can rotate around a second rotation axis; The axis of the first rotating shaft intersects perpendicularly with the axis of the second rotating shaft; The lens is arranged on the second frame. 9 . The three-dimensional MEMS scanning mirror according to claim 8 , wherein the mirror and the second frame are connected by a flexible connector. 10 . 10 . The three-dimensional MEMS scanning mirror according to claim 9 , wherein if the lens is circular and the second frame is a circular frame, the flexible connecting member is centered on the center of the lens. 11 . Sector ring flexible connector.

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