Optical scanning device and laser radar system

Abstract

The invention discloses an optical scanning device which can be applied to the field of target detection and comprises a slow axis driving module, a fast axis galvanometer module, a driving detection module and a supporting module. A fast-axis driving magnet used for driving a fast-axis galvanometer module is fixed on a supporting module, and only the fast-axis galvanometer module is connected with a slow-axis driving module, so that the slow-axis driving module only needs to drive the fast-axis galvanometer module to move in the slow-axis direction, and does not need to drive the fast-axis driving magnet to move together; therefore, the load of the slow-axis driving module is reduced, the power consumption of the optical scanning device is effectively reduced, the response speed of the fast-axis galvanometer module moving in the slow-axis direction is improved, and the performance of the optical scanning device is ensured.

Description

Technical Field

[0001] The present application relates to the field of target detection, and in particular to an optical scanning device and a laser radar system. Background Art

[0002] LiDAR is a radar system that detects the position, speed and other characteristic quantities of a target by emitting laser beams. It has high distance resolution, angular resolution and speed resolution, strong anti-interference capability and can work around the clock. It is not dependent on external lighting conditions or the radiation characteristics of the target itself and is an essential sensing device for future unmanned driving.

[0003] Generally speaking, a laser radar includes a scanning device for scanning surrounding targets with lasers. During the operation of the scanning device, by emitting lasers to continuously scan the target, the data of all target points on the target can be obtained, and combined with the height of the laser and the laser scanning angle, an accurate three-dimensional image of the surrounding environment can be obtained.

[0004] Specifically, the laser radar scanning device uses a reflector that moves in two directions at the same time to reflect the laser, thereby realizing the laser scanning of the target object. The two directions in which the reflector moves are called the slow axis direction and the fast axis direction. The movement speed of the reflector in the slow axis direction is slower, and the movement speed in the fast axis direction is faster.

[0005] In the related art, the scanning device mainly drives the reflector to move in the fast axis direction and the slow axis direction through the driving mechanism in the fast axis direction and the driving mechanism in the slow axis direction. However, the scanning device in the related art has the problems of high power consumption and slow response speed of the reflector in the slow axis direction, which affects the overall performance of the laser radar. Summary of the invention

[0006] The present application provides an optical scanning device, which can effectively reduce the power consumption of the optical scanning device and improve the response speed of the slow axis, thereby ensuring the performance of the optical scanning device.

[0007] The first aspect of the present application provides an optical scanning device, which can be used in a laser radar system. The optical scanning device includes: a slow-axis drive module, a fast-axis galvanometer module, a drive detection module and a support module. Among them, the fast-axis galvanometer module includes a reflective mirror surface, which is used to reflect laser light to achieve laser scanning of an object. The drive detection module includes a fast-axis drive magnet.

[0008] The slow axis drive module is mechanically connected to the fast axis galvanometer module, and is used to drive the fast axis galvanometer module in the slow axis direction. For example, the slow axis drive module can be arranged on one side of the fast axis galvanometer module, and fixedly connected to the fast axis galvanometer module through a rotating shaft, so as to drive the fast axis galvanometer module to reciprocate in the slow axis direction through the rotating shaft.

[0009] The fast-axis drive magnet is arranged close to the fast-axis galvanometer module, and is used to drive the reflective mirror surface in the fast-axis galvanometer module in the fast-axis direction. There is no connection between the fast-axis drive magnet and the fast-axis galvanometer module, that is, the fast-axis drive magnet is only close to the fast-axis galvanometer module, and there is a gap and no contact between the fast-axis drive magnet and the fast-axis galvanometer module.

[0010] The support module is used to fix the drive detection module. In addition, the support module can also fix the slow axis drive module at the same time.

[0011] In the present solution, the fast-axis driving magnet used to drive the fast-axis galvanometer module is fixed on the supporting module, and only the fast-axis galvanometer module is connected to the slow-axis driving module, so that the slow-axis driving module only needs to drive the fast-axis galvanometer module to move in the slow-axis direction, and no longer needs to drive the fast-axis driving magnet to move, thereby reducing the load of the slow-axis driving module, thereby effectively reducing the power consumption of the optical scanning device and improving the response speed of the fast-axis galvanometer module when moving in the slow-axis direction, thereby ensuring the performance of the optical scanning device.

[0012] In a possible implementation, the fast-axis galvanometer module further includes: a fast-axis drive coil and an external support frame. The fast-axis drive coil and the reflective mirror are both arranged in the external support frame, and the fast-axis drive coil is used to drive the reflective mirror to rotate relative to the external support frame in the fast-axis direction under the magnetic force of the fast-axis drive magnet. The external support frame is mechanically connected to the slow-axis drive module, and is used to drive the fast-axis drive coil and the reflective mirror to rotate in the slow-axis direction under the drive of the slow-axis drive module.

[0013] In this solution, the fast-axis galvanometer module uses a simple voice coil motor structure to drive the reflective mirror. Since the fast-axis drive coil is in the magnetic field of the fast-axis drive magnet, after a current of a fixed variable frequency is passed through the fast-axis drive coil, a Lorentz magnetic force will be generated under the movement of the magnetic field, thereby driving the reflective mirror to rotate back and forth in the external support frame, thereby achieving the driving of the reflective mirror in the fast-axis direction in a simple and low-cost manner.

[0014] In a possible implementation, the fast-axis galvanometer module further includes: a reed structure. The reed structure includes the external support frame described above. The reflective mirror is arranged on the front of the reed structure, and the fast-axis drive coil is arranged on the back of the reed structure. The area of ​​the reed structure for arranging the reflective mirror and the fast-axis drive coil can be deformed in the fast-axis direction.

[0015] In this solution, by using a deformable reed structure to set the reflective mirror and the fast-axis drive coil, the fast-axis drive coil can drive the reflective mirror to resonate in the fast-axis direction, thereby meeting the demand for high-frequency scanning in the fast-axis direction.

[0016] In a possible implementation, the leaf spring structure includes: a folding beam and an external support frame in the same plane, and the folding beam is connected to the external support frame. The reflective mirror and the fast axis drive coil can be arranged in the folding beam, and the folding beam can be deformed relative to the external support frame in the fast axis direction to provide a restoring force for the reflective mirror when performing resonant motion.

[0017] The folded beam may include a torsion beam distributed on both sides of the reflective mirror, and the torsion beam has a folded structure. The torsion beam can deform around the fast axis (ie twist around the fast axis), thereby providing the reflective mirror with the stiffness and restoring force required for resonant motion.

[0018] In this solution, through the design of the folded beam, a larger angle of torsion can be achieved under a smaller torsional stress, so as to improve the reliability of the long-term movement of the reflective mirror and facilitate the long-term high-frequency resonant movement of the reflective mirror.

[0019] In a possible implementation, the thickness of the folded beam is 0.1 mm-2 mm.

[0020] In a possible implementation, the leaf spring structure further includes a mirror support frame, the mirror support frame is connected to the folding beam, and the reflective mirror is arranged on the mirror support frame. In addition, the mirror support frame may be in a cross shape or a cross shape.

[0021] In this solution, by providing a mirror support frame of a specific shape, it is possible to reduce the area of ​​the mirror support frame while providing sufficient support for the reflective mirror, thereby effectively reducing the overall mass of the fast-axis galvanometer module and reducing the load of the slow-axis drive module.

[0022] In a possible implementation, the fast axis drive magnet includes: a first boss magnet and a second boss magnet, wherein the magnetic field direction of the first boss magnet is opposite to the magnetic field direction of the second boss magnet. The convex portion of the first boss magnet and the convex portion of the second boss magnet are inserted into the leaf spring structure to enhance the magnetic field around the fast axis drive coil during movement.

[0023] In this solution, by designing an interpolated boss magnetic field as a fast-axis drive magnet, the magnetic field around the fast-axis drive coil during movement can be enhanced, ensuring that the intensity of the magnetic field to which the fast-axis drive coil is subjected to changes little during movement, greatly reducing the power consumption of the fast-axis drive coil 103 during the driving process, and ensuring the drive linearity.

[0024] In a possible implementation, the fast axis drive magnet further includes: a first magnetic material and a second magnetic material; the first magnetic material and the second magnetic material are disposed between the first boss magnet and the second boss magnet to optimize the magnetic field distribution of the first boss magnet and the second boss magnet.

[0025] In this solution, by arranging two magnetic materials between the two boss magnets, the magnetic field distribution direction can be ensured to be as close as possible to the fast axis drive coil, thereby providing a sufficiently large Lorentz force for the fast axis drive coil to reduce the driving power consumption of the fast axis drive coil.

[0026] In a possible implementation, the first magnetic material includes a first cylindrical magnet, the second magnetic material includes a second cylindrical magnet, and the magnetic field direction of the first cylindrical magnet is opposite to the magnetic field direction of the second cylindrical magnet.

[0027] In a possible implementation, the fast-axis galvanometer module includes: a micro-electromechanical system (MEMS) micro-mirror. The MEMS micro-mirror includes an integrally formed reflective mirror surface, a fast-axis drive coil, and an external support frame.

[0028] In a possible implementation, the MEMS micromirror further includes: a folded routing beam and a support beam. The fast axis drive coil is connected to the support beam through the folded routing beam, and the fast axis drive coil rotates around the support beam in the fast axis direction; the folded routing beam is used to reduce the torsional stress of the fast axis drive coil during the torsion process; the support beam is used to provide support for the rotation of the fast axis drive coil.

[0029] In this solution, the MEMS micromirror manufactured by MEMS technology can better realize drive integration, and the fast-axis drive coil and the reflective mirror are both manufactured by MEMS technology. The silicon material used to make the reflective mirror has high rigidity, making it easier for the reflective mirror to achieve high-frequency resonance, and the mirror is light in weight and has low drive power consumption.

[0030] In a possible implementation, the fast axis drive magnet includes: at least two magnets, the magnetic fields of the at least two magnets are in opposite directions; the at least two magnets are inserted into the fast axis drive coil to enhance the magnetic field around the fast axis drive coil during movement.

[0031] In a possible implementation, the slow axis drive module includes: a rotating shaft, an arc magnet, an arc core, and a slow axis drive coil. The arc magnet and the arc core are located in the same horizontal plane, and the arc magnet and the arc core are concentric arcs, for example, the arc magnet and the arc core are arcs with the slow axis as the center. The arc magnet is fixed to one side of the rotating shaft, and the other side of the rotating shaft is mechanically connected to the fast axis galvanometer module. The slow axis drive coil is wound on the arc core, and the slow axis drive coil will generate a magnetic field when powered on, so the arc magnet drives the rotating shaft to swing back and forth in the slow axis direction under the action of the magnetic force.

[0032] In this solution, the arc-shaped structure design of the arc-shaped iron core and the arc-shaped magnet makes the magnetic field distribution corresponding to the arc-shaped iron core symmetrical in the center, thereby ensuring that the arc-shaped magnet can generate a certain restoring force during the back-and-forth swinging process, thereby improving and reducing the power consumption of the back-and-forth swinging. In addition, the arc-shaped magnets and coils can effectively reduce the volume of the drive structure and reduce the load of the slow-axis drive module itself, so that the slow-axis drive module has the advantages of simple structure, small volume and fast response. In addition, the slow-axis drive module actually drives the shaft to move with the arc-shaped magnet instead of the slow-axis drive coil, that is, the slow-axis drive coil is wound on a fixed arc-shaped iron core, so there is no need to consider the power supply and movement stability of the coil during the movement, which can greatly improve the reliability and stability of the slow-axis drive structure.

[0033] In a possible implementation, the drive detection module further includes: an angle detection sensor, which is arranged on the support module and is arranged close to the fast-axis galvanometer module. The angle detection sensor is used to obtain angle change information of the fast-axis galvanometer module in the slow axis direction and the fast axis direction, so as to more accurately control the movement of the fast-axis galvanometer module in the slow axis direction and the fast axis direction.

[0034] In one possible implementation, the angle detection sensor includes: a light source and a photodetector array; the light source is used to emit a first light beam with an angle to the fast-axis galvanometer module; the photodetector array is used to receive a second light beam reflected back by the fast-axis galvanometer module and detect the intensity of the second light beam. Specifically, when the reflective mirror on the fast-axis galvanometer module rotates, the light intensity area and the received light intensity on each photodetector will change, so the output signal of the photodetector will also change. In this way, based on the relationship between the light intensity change of the photodetector and the rotation angle of the reflective mirror, the rotation angle of the reflective mirror can be determined by calculating the output signal of each photodetector.

[0035] In this solution, two-dimensional angle detection is achieved through the cooperation of a light source and an optical detector, which can ensure that the angle detection sensor has high working stability while being small in size, can adapt to various working environments and achieve high-precision detection.

[0036] In a possible implementation, the angle detection sensor further includes: a packaging substrate and a sensor driving board. The light source and the photodetector array are mounted on the packaging substrate, the packaging substrate is fixed to the sensor driving board, and the packaging substrate is electrically connected to the sensor driving board, and the sensor driving board is used to drive the light source and the photodetector array to work through the packaging substrate.

[0037] In this solution, by mounting the light source and the photodetector array onto a packaging substrate and then achieving electrical connection with the sensor driver board through the packaging substrate, it is no longer necessary to pre-package the light source and the photodetector array and then mount them onto the sensor driver board, and the assembly of the angle detection sensor can be achieved at a lower cost.

[0038] In a possible implementation, the size of the photodetector array is greater than or equal to 2*2. For example, the size of the photodetector array is 2*2 or 4*4, which can ensure that the angle detection sensor can achieve high-precision and large-angle detection.

[0039] A second aspect of the present application provides a laser radar system, comprising an optical scanning device as described in any implementation method of the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A schematic diagram of the operation of a laser radar scanning device provided in an embodiment of the present application;

[0041] Figure 2 A schematic diagram of the working principle of an optical scanning device provided in an embodiment of the present application;

[0042] Figure 3 A schematic diagram of the structure of an optical scanning device provided in an embodiment of the present application;

[0043] Figure 4 A motion schematic diagram of a fast-axis galvanometer module provided in an embodiment of the present application;

[0044] Figure 5 A schematic diagram of the assembly of a fast-axis galvanometer module provided in an embodiment of the present application;

[0045] Figure 6 A schematic diagram of the front structure of the reed structure provided in an embodiment of the present application;

[0046] Figure 7 A schematic diagram of the back structure of the reed structure provided in an embodiment of the present application;

[0047] Figure 8 A schematic diagram of the movement of a folding beam provided in an embodiment of the present application;

[0048] Fig. 9 A cross-sectional schematic diagram of a reed structure provided in an embodiment of the present application;

[0049] Fig.10 A schematic diagram of the structure of a drive detection module provided in an embodiment of the present application;

[0050] Fig.11 A schematic diagram of the structure of a fast axis drive magnet provided in an embodiment of the present application;

[0051] Fig.12 A schematic structural diagram of another fast-axis galvanometer module provided in an embodiment of the present application;

[0052] Fig.13 A schematic diagram of coupling a MEMS micromirror with a slow axis driving module and a driving detection module provided in an embodiment of the present application;

[0053] Fig.14 A schematic diagram of the arrangement of an angle detection sensor on a drive detection module provided in an embodiment of the present application;

[0054] Fig.15 A schematic diagram of the structure of an angle detection sensor provided in an embodiment of the present application;

[0055] Fig.16 A schematic diagram of the working principle of the angle sensor provided in the embodiment of the present application;

[0056] Fig.17 A schematic diagram of the structure of a slow axis drive module provided in an embodiment of the present application;

[0057] Fig.18 A schematic diagram of the magnetic field distribution inside the slow axis drive module provided in an embodiment of the present application;

[0058] Fig.19 A schematic diagram of a driving control process of an optical scanning device provided in an embodiment of the present application;

[0059] Fig. 20 A schematic diagram of a driving waveform of an optical scanner provided in an embodiment of the present application. DETAILED DESCRIPTION

[0060] In order to make the purpose, technical solutions and advantages of the present application clearer, the embodiments of the present application are described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only embodiments of a part of the present application, rather than all embodiments. It is known to those of ordinary skill in the art that with the emergence of new application scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0061] The terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the descriptions used in this way can be interchanged where appropriate, so that the embodiments can be implemented in a sequence other than that illustrated or described in the present application. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or modules is not necessarily limited to those steps or modules that are clearly listed, but may include other steps or modules that are not clearly listed or inherent to these processes, methods, products or devices. The naming or numbering of the steps that appear in the present application does not mean that the steps in the method flow must be executed in the time / logical sequence indicated by the naming or numbering. The process steps that have been named or numbered can change the execution order according to the technical purpose to be achieved, as long as the same or similar technical effects can be achieved. The division of units in this application is a logical division. There may be other division methods when it is implemented in actual applications. For example, multiple units can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, and the indirect coupling or communication connection between units can be electrical or other similar forms, which are not limited in this application. In addition, the units or sub-units described as separate components may or may not be physically separated, may or may not be physical units, or may be distributed in multiple circuit units, and some or all of the units may be selected according to actual needs to achieve the purpose of the present application.

[0062] To facilitate understanding, the technical terms involved in this embodiment are first introduced below.

[0063] (1) Light Detection and Ranging (LiDAR)

[0064] LiDAR is an optical sensor technology that uses a scanning laser beam to illuminate an object and measures the time it takes for the laser beam to bounce back from the object to determine the distance and position of the object or the properties of the object.

[0065] (2) Micro Electro Mechanical System (MEMS)

[0066] MEMS is a high-tech electronic mechanical device developed on the basis of microelectronics technology (semiconductor manufacturing technology) that integrates technologies such as lithography, corrosion, thin film, silicon micromachining, non-silicon micromachining and precision machining.

[0067] Generally speaking, MEMS is a micro device or system that integrates micro sensors, micro actuators, micro mechanical structures, micro power sources, micro energy, signal processing and control circuits, high-performance electronic integrated devices, interfaces, and communications.

[0068] (3)MEMS micromirror

[0069] MEMS micromirror refers to a galvanometer mirror made using MEMS technology.

[0070] (4) Resonant frequency

[0071] The resonant frequency is also called the natural frequency or the inherent frequency. When an object is vibrating freely, its displacement changes with time according to the sine or cosine law. The frequency of vibration has nothing to do with the initial conditions, but is only related to the inherent characteristics of the system (such as mass, shape, material, etc.), which is called the resonant frequency. Generally speaking, the resonant frequency of an object is related to its hardness, mass, and size. When it is deformed, the elastic force restores it. The elastic force is mainly related to the size and hardness, and the mass affects its acceleration. For objects of the same shape, the resonant frequency is high if the hardness is high, and the frequency of the resonant frequency is low if the mass is large.

[0072] For a simple system, the resonant frequency is:

[0073]

[0074] Among them, k is the stiffness coefficient, also known as the stiffness coefficient or stubbornness coefficient, which describes the magnitude of the elastic force generated by unit deformation. The larger the k value, the greater the force required for deformation; m is the equivalent mass of the vibrating object, which is generally related to the shape and mass of the object. For objects of the same shape, the larger the mass, the greater the equivalent mass.

[0075] (5) Voice Coil Motor

[0076] The voice coil motor is a special form of direct drive motor. The voice coil motor has the characteristics of simple structure, small size, high speed, high acceleration and fast response. The working principle of the voice coil motor is that when the energized coil (conductor) is placed in a magnetic field, a force will be generated. The magnitude of the force is proportional to the current applied to the coil. Therefore, the voice coil motor manufactured based on this principle can move in a straight line or arc.

[0077] (6) Operational amplifier

[0078] Operational amplifiers, often referred to as op amps, are circuit units with very high magnification. In actual circuits, they are usually combined with feedback networks to form a certain functional module. An op amp is an amplifier with a special coupling circuit and feedback. Its output signal can be the result of mathematical operations such as addition, subtraction, differentiation, and integration of the input signal. It was named "operational amplifier" because it was used in analog computers to perform mathematical operations in the early days.

[0079] (7) Analog to digital converter (ADC)

[0080] An analog-to-digital converter usually refers to an electronic component that converts an analog signal into a digital signal. A common analog-to-digital converter converts an input voltage signal into an output digital signal. Since the digital signal itself has no practical meaning and only represents a relative size, any analog-to-digital converter requires a reference analog quantity as a conversion standard. The more common reference standard is the maximum convertible signal size. The output digital quantity represents the size of the input signal relative to the reference signal.

[0081] (8) Digital to analog converter (DAC)

[0082] A digital-to-analog converter is a device that converts continuous analog signals into discrete digital signals.

[0083] In the LiDAR system, the ranging capability, number of scanning lines and volume of the LiDAR have gradually become the focus of product competitiveness. The ranging capability of the LiDAR is proportional to the aperture of the scanning device on the LiDAR. The larger the aperture of the scanning device, the farther the ranging capability of the LiDAR. The number of scanning lines of the scanning device on the LiDAR depends on the scanning frequency of the fast axis in the scanning device; however, the larger the aperture of the scanning device, the greater the mass of the scanning device, which in turn affects the scanning frequency of the scanning device. Therefore, in the LiDAR system, the ranging capability and number of scanning lines are closely related to the design of the scanner.

[0084] Specifically, the laser radar includes a scanning device for scanning the surrounding targets with lasers. During the operation of the scanning device, by emitting lasers to continuously scan the target, the data of all target points on the target can be obtained, and combined with the height of the laser and the laser scanning angle, an accurate three-dimensional image of the surrounding environment can be obtained.

[0085] See also Figure 1 , Figure 1 The following is a schematic diagram of the operation of a laser radar scanning device provided in an embodiment of the present application. Figure 1As shown, the laser radar scanning device reflects the laser through a reflector that moves in two directions at the same time, thereby realizing the laser scanning of the target object. Among them, the two directions in which the reflector moves are called the slow axis direction and the fast axis direction respectively. The movement speed of the reflector in the slow axis direction is slower, and the movement speed in the fast axis direction is faster. From the scanning pattern of the scanning device, it can be seen that the reflector of the scanning device moves in the fast axis direction to realize the up and down scanning of the laser (that is, to realize the movement of the laser in the vertical direction), and the reflector of the scanning device moves in the slow axis direction to realize the left and right scanning of the laser (that is, to realize the movement of the laser in the horizontal direction), which finally makes the scanning pattern wavy.

[0086] It is found through research that in the related art, the scanning device mainly drives the reflector to move in the fast axis direction and the slow axis direction through the driving mechanism in the fast axis direction and the driving mechanism in the slow axis direction. Among them, the driving mechanism in the slow axis direction includes components such as motor coils, motor magnets and rotating shafts, and the rotating shaft is driven to rotate by the motor coils and the motor magnets. The driving mechanism in the fast axis direction and the reflector are connected to the rotating shaft in the slow axis direction, and the rotating shaft in the slow axis direction drives the driving mechanism and the reflector in the fast axis direction to rotate at the same time. While the driving mechanism and the reflector in the fast axis direction are driven to rotate in the slow axis direction, the driving mechanism in the fast axis direction simultaneously drives the reflector to rotate in the fast axis direction, so that the reflector rotates in the slow axis direction and the fast axis direction at the same time. Among them, the driving mechanism in the fast axis direction often uses a magnet and an energized coil to drive the reflector to rotate in the fast axis direction. Specifically, in the related art, the reflector and the magnet are fixed, and the magnet is driven to rotate in the fast axis direction by the energized coil, so that the magnet drives the reflector to move in the fast axis direction at the same time.

[0087] However, since the driving mechanism in the slow axis direction needs to drive the driving mechanism and the reflector in the fast axis direction at the same time, the load on the driving mechanism in the slow axis direction is relatively large, which in turn causes the scanning device to have high power consumption and slow response speed of the reflector in the slow axis direction, affecting the overall performance of the lidar.

[0088] In view of this, the present embodiment provides an optical scanning device, which fixes the fast-axis driving magnet used to drive the fast-axis galvanometer module on the supporting module, and only connects the fast-axis galvanometer module to the slow-axis driving module, so that the slow-axis driving module only needs to drive the fast-axis galvanometer module to move in the slow-axis direction, and no longer needs to drive the fast-axis driving magnet to move, thereby reducing the load of the slow-axis driving module, thereby effectively reducing the power consumption of the optical scanning device and improving the response speed of the fast-axis galvanometer module when moving in the slow-axis direction, thereby ensuring the performance of the optical scanning device.

[0089] The optical scanning device provided in the embodiment of the present application can be applied to a laser radar system, and the laser radar system can be applied to intelligent systems such as autonomous driving vehicles, intelligent robots, virtual reality (VR) systems, and augmented reality (AR) systems.

[0090] See also Figure 2 , Figure 2 The following is a schematic diagram of the working principle of an optical scanning device provided in an embodiment of the present application. Figure 2 As shown, the optical scanning device provided in this embodiment can be a core component deployed in a laser radar system, and can complete two-dimensional scanning by laser scanning in the horizontal and vertical directions. Among them, the direction in which the laser scanning frequency is slow is called the slow axis direction, and the direction in which the laser scanning frequency is fast is called the fast axis direction, and the scanning frequency ratio of the fast axis direction to the slow axis direction is usually greater than 10. Among them, in the fast axis direction, the high-frequency vibration of the reflector can be achieved by a torsion beam, and its motion mode is resonant motion; while in the slow axis direction, linear drive is generally used, and the motion mode is a sawtooth wave or a triangular wave. Therefore, the pattern finally formed by the two-dimensional scanning is grating-shaped.

[0091] The application scenario and working principle of the optical scanning device provided by this embodiment are introduced above, and the specific structure of the optical scanning device will be introduced below.

[0092] See also Figure 3 , Figure 3 Schematic diagram of the structure of an optical scanning device provided in an embodiment of the present application. Figure 3 As shown, the optical scanning device includes a fast-axis galvanometer module 10 , a slow-axis driving module 20 , a driving detection module 30 and a supporting module 40 .

[0093] The fast-axis galvanometer module 10 includes a reflective mirror 101, which is used to reflect the laser to achieve laser scanning of the object. In addition, in this embodiment, the reflective mirror 101 on the fast-axis galvanometer module 10 moves in the slow axis direction and the fast axis direction at the same time to achieve laser scanning in the slow axis direction and the fast axis direction. Specifically, the reflective mirror 101 moves around the slow axis in the slow axis direction, and around the fast axis in the fast axis direction, and the slow axis and the fast axis are two axes perpendicular to each other on the same plane.

[0094] The slow axis driving module 20 is mechanically connected to the fast axis galvanometer module 10, and is used to drive the fast axis galvanometer module 10 in the slow axis direction. Specifically, the slow axis driving module 20 can be arranged on one side of the fast axis galvanometer module 10 (such as Figure 3 The fast-axis galvanometer module 10 is fixedly connected to the fast-axis galvanometer module 10 via a rotating shaft, so that the fast-axis galvanometer module is driven to reciprocate in the slow-axis direction via the rotating shaft.

[0095] The drive detection module 30 includes a fast axis drive magnet ( Figure 3 The fast-axis drive magnet is arranged close to the fast-axis galvanometer module 10, and is used to drive the reflective mirror surface 101 in the fast-axis galvanometer module 10 in the fast-axis direction. In addition, there is no connection between the fast-axis drive magnet and the fast-axis galvanometer module 10, that is, the fast-axis drive magnet is only close to the fast-axis galvanometer module 10, and there is a gap and no contact between the fast-axis drive magnet and the fast-axis galvanometer module 10. For example, Figure 3 As shown in , the fast axis driving magnet is disposed below the fast axis galvanometer module 10 , and the fast axis driving magnet does not contact the fast axis galvanometer module 10 , but drives the reflective mirror surface 101 on the fast axis galvanometer module 10 to reciprocate in the fast axis direction through magnetic force.

[0096] The support module 40 may be used to fix the drive detection module 30. For example, Figure 3 As shown in FIG. 1 , the support module 40 is in the shape of a groove, and the support module 40 is disposed below the drive detection module 30 to fix and support the drive detection module 30. In addition, the support module 40 can also be used to fix and support the slow axis drive module 20. For example, Figure 3 As shown in the figure, the slow axis driving module 20 is fixedly arranged on the left side of the supporting module 40, and the slow axis driving module 20 is arranged on the outside of the supporting module 40. The rotating shaft on the slow axis driving module 20 is mechanically connected to the fast axis galvanometer module 10 located in the supporting module 40 through the rotating shaft hole on the left side of the supporting module 40. In addition, a bearing hole is also arranged on the right side of the supporting module 40 to provide support for the fast axis galvanometer module 10 during the rotation process of the fast axis galvanometer module 10.

[0097] See also Figure 4 , Figure 4 The following is a schematic diagram of the motion of a fast-axis galvanometer module provided in an embodiment of the present application. Figure 4 As shown, based on Figure 3 In the structure shown in , the fast-axis galvanometer module 10 rotates in the slow-axis direction under the drive of the slow-axis driving module 20, and rotates in the fast-axis direction under the drive of the driving detection module 30. The plane where the reflective mirror surface 101 in the fast-axis galvanometer module 10 is located is taken as the reference plane. On the reference plane, the rotation axis of the slow-axis driving module 20 can be regarded as the slow axis, and the direction in which the reflective mirror surface 101 rotates around the slow axis can be regarded as the slow axis direction. On the same reference plane, the fast axis is perpendicular to the slow axis, that is, the fast axis can be located at the center of the reflective mirror surface 101 and perpendicular to the slow axis, and the direction in which the reflective mirror surface 101 rotates around the fast axis can be regarded as the fast axis direction.

[0098] Depend on Figure 3As can be seen from the structure introduced above, the fast-axis galvanometer module 10 and the drive detection module 30 are separated, and the slow-axis drive module 20 is only mechanically connected to the fast-axis galvanometer module, and only needs to drive the fast-axis galvanometer module 10 to rotate, and no longer needs to drive the drive detection module 30 to rotate, which effectively reduces the load of the slow-axis drive module 10, thereby effectively reducing the power consumption of the optical scanning device and improving the response speed of the fast-axis galvanometer module 10 when moving in the slow-axis direction (that is, the fast-axis galvanometer module 10 can respond more quickly to changes in the rotation direction of the slow-axis direction).

[0099] In order to facilitate understanding of the driving principle in the fast axis direction, the specific structures of the fast axis galvanometer module and the driving detection module will be introduced in detail below.

[0100] Optionally, the fast-axis galvanometer module includes: a reflective mirror, a fast-axis drive coil, and an external support frame. The external support frame may be a square structure, in which the fast-axis drive coil and the reflective mirror are both arranged inside the external support frame, and the fast-axis drive coil is used to drive the reflective mirror to rotate relative to the external support frame in the fast-axis direction under the magnetic force of the fast-axis drive magnet. Specifically, the fast-axis galvanometer module uses a voice coil motor structure to drive the reflective mirror. Since the fast-axis drive coil is in the magnetic field of the fast-axis drive magnet, after the fast-axis drive coil is passed with a current of a fixed variable frequency, a Lorentz magnetic force will be generated under the movement of the magnetic field, thereby driving the reflective mirror to rotate back and forth in the external support frame.

[0101] In addition, the external support frame is mechanically connected to the slow axis drive module, and is used to drive the fast axis drive coil and the reflective mirror surface to rotate in the slow axis direction under the drive of the slow axis drive module. In other words, the external support frame is driven by the slow axis drive module, thereby driving the fast axis drive coil and the reflective mirror surface to rotate in the slow axis direction; and, because the fast axis drive coil is in turn driven by the magnetic field of the fast axis drive magnet, the reflective mirror surface is driven to rotate relative to the external support frame, thereby enabling the reflective mirror surface to move in the slow axis direction and the fast axis direction at the same time.

[0102] See also Figure 5 , Figure 5 The following is a schematic diagram of the assembly of a fast axis galvanometer module provided in an embodiment of the present application. Figure 5 As shown, the fast-axis galvanometer module includes: a reflective mirror 101, a reed structure 102 and a fast-axis drive coil 103. Among them, the reed structure 102 includes the above-mentioned external support frame. The reflective mirror 101 can be made of high-hardness materials such as silicon or sapphire, and the surface of the reflective mirror 101 is coated to improve the reflectivity. The coating on the surface of the reflective mirror 101 can be a metal film or a dielectric film, and this embodiment does not make specific restrictions on this. The reed structure 102 can be made of high-strength metal sheets such as titanium alloys and high-carbon steel sheets to ensure the stability of the structure.

[0103] Specifically, the reflective mirror 101 is arranged on the front side of the reed structure 102, and the fast axis driving coil 103 is arranged on the back side of the reed structure, and the fast axis driving coil 103 is close to the fast axis driving magnet arranged below the reed structure 102. The area of ​​the reed structure 102 for arranging the reflective mirror 101 and the fast axis driving coil 103 can be deformed in the fast axis direction, so that the fast axis driving coil 103 can drive the reflective mirror 101 to rotate in the fast axis direction.

[0104] See also Figure 6 and Figure 7 , Figure 6 A schematic diagram of the front structure of the reed structure provided in an embodiment of the present application; Figure 7 This is a schematic diagram of the back structure of the reed structure provided in the embodiment of the present application. Figure 6 As shown, the leaf spring structure 102 includes: a folding beam 109 , a mirror support frame 107 and an external support frame 111 in the same plane. The folding beam 109 is connected to the mirror support frame 107 , and the folding beam 109 is also connected to the external support frame 111 .

[0105] The mirror support frame 107 can be disposed in the folding beam 109, and the reflective mirror 101 is arranged on the mirror support frame 107. The mirror support frame 107 provides support for the reflective mirror 101 and reduces the dynamic surface change of the reflective mirror 101 during the movement of the reflective mirror 101, thereby ensuring that the reflective mirror 101 can normally reflect the laser during the movement. For example, the back of the reflective mirror 101 can be bonded to the mirror support frame 107 by glue.

[0106] Optionally, the mirror support frame 107 may be in a cross shape or a cross shape, thereby providing sufficient support for the reflective mirror 101 while reducing the area of ​​the mirror support frame 107, thereby effectively reducing the overall mass of the fast-axis galvanometer module and reducing the load of the slow-axis drive module.

[0107] The folded beam 109 can be deformed relative to the external support frame 111 in the fast axis direction, thereby providing a restoring force for the reflective mirror 101 arranged on the mirror support frame 107 when performing resonant motion. Figure 6As shown, the folding beam 109 includes torsion beams distributed on both sides of the mirror support frame 107, and the torsion beams are in a folding structure. The mirror support frame 107 is in a cross shape, and one axis in the cross shape of the mirror support frame 107 serves as a fast axis, and the folding beam 109 is connected to two points of the mirror support frame 107 on the fast axis. The torsion beams distributed on both sides of the mirror support frame 107 in the folding beam 109 can deform around the fast axis on the mirror support frame 107 (i.e. twist around the fast axis), thereby providing the mirror support frame 107 with the stiffness and restoring force required for resonant motion. Among them, the folding beam 109 can achieve a larger angle torsion under a smaller torsional stress, so as to improve the reliability of the long-term motion of the reflective mirror 101.

[0108] For example, see Figure 8 , Figure 8 A schematic diagram of the movement of a folding beam provided in an embodiment of the present application. Figure 8 As shown, the torsion beams distributed on both sides of the mirror support frame 107 in the folded beam 109 are deformed around the fast axis in the middle of the mirror support frame 107, wherein the torsion beam on one side is twisted downward, and the torsion beam on the other side is twisted upward, thereby driving the mirror support frame 107 in the middle to flip around the fast axis. In addition, thanks to the folding structure design of the folded beam 109, the torsion beam on the outside of the folded beam 109 can deform at a larger angle, while the torsion beam on the inside of the folded beam 109 can deform at a smaller angle, thereby providing the reflective mirror 101 with a larger angle of torsion and only generating a smaller torsional stress through the folded torsion beam, which can facilitate the reflective mirror 101 to perform high-frequency resonant motion for a long time.

[0109] In general, the folded beam 109 is based on a torsion beam with a folded structure, and the folded beam 109 has the ability of elastic deformation (similar to a spring), and can be deformed under the drive of the fast axis drive coil to drive the reflective mirror 101. In addition, the folded beam 109 can ensure that only a small torsional stress is generated at a large movement angle, thereby ensuring the reliability of the long-term movement of the reflective mirror 101.

[0110] In addition, the reed structure 102 also includes conductive pins 108 and connection holes 110. The conductive pins 108 can be distributed on both sides of the reed structure 102 to provide a conductive interface for the drive coil to connect to an external power source. The connection holes 110 can also be distributed on both sides of the reed structure 102 to achieve mechanical connection with the slow axis drive module.

[0111] The back structure of the reed structure 102 is as follows Figure 7As shown, the back structure of the reed structure 102 includes a fast axis drive coil 103, a coil connection pad 104, a connection trace 105 and a circuit conduction hole 106. The input end and the output end of the fast axis drive coil 103 are respectively welded to the coil connection pads 104 at the upper and lower ends of the reed structure 102. In addition, the coil connection pad 104 is also connected to the connection trace 105. The connection trace 105 is arranged along the folding beam 109, and is connected to the front of the reed structure 102 through the circuit conduction hole 106, and then connected to the external power supply through the conductive pin 108.

[0112] See also Fig. 9 , Fig. 9 The cross-sectional diagram of the reed structure provided in the embodiment of the present application is shown in FIG. Fig. 9 As shown, the cross-sectional structure of the above-mentioned reed structure 102 mainly includes the electrical interconnection structure between the fast-axis drive coil 103 and the external circuit. Among them, the bottom of the reed structure 102 is a titanium alloy substrate, which includes two layers of AD glue insulation layers, and a conductive copper foil is arranged between the two layers of AD glue insulation layers. In this way, based on the printed circuit board (PCB) wiring process, the fast-axis drive coil 103 is routed to the external support frame 111 through the folding beam 109, and then connected to the front of the reed structure 102 through the circuit conduction hole 106, completing the wiring process of the entire titanium alloy reed. In addition, the coil connection pad 104 on the front of the reed structure 102 is connected to the flexible printed circuit (Flexible Printed Circuit, FPC) soft cable through the wire bonding process to complete the electrical interconnection with the external circuit.

[0113] In general, this solution uses high-strength metal sheets such as titanium alloy and high-carbon steel sheets to form the reed structure in the fast-axis galvanometer module, which has extremely low manufacturing costs; and the specially designed folded beam structure on the reed structure can ensure that the reflective mirror surface achieves smaller torsional stress at a larger movement angle to improve reliability. In addition, the fast-axis galvanometer module is actually driven by the fast-axis drive coil (that is, the coil moves instead of the magnet), which can effectively reduce the drive load and cooperate with the folded beam to form a "spring damping" second-order system, thereby achieving high-frequency resonant motion through a lower driving force, ensuring the scanning frequency of the laser in the fast-axis direction.

[0114] The frequency of the current large-aperture MEMS scanning galvanometer is not fast enough to achieve fast LiDAR images, and the aperture is not large enough. Metal materials have better ductility and toughness than silicon materials, so metal-based micro-scanning mirrors are more reliable than silicon-based MEMS micro-mirrors. In this embodiment, the following design requirements are proposed for large-mirror metal micro-mirrors in terms of mirror size, torsion angle, characteristic frequency, material properties, chip size, and processing technology:

[0115] (1) Mirror size: The mirror diameter is greater than or equal to 20 mm.

[0116] (2) Chip size: less than or equal to 30 mm in width and less than or equal to 50 mm in length.

[0117] (3) Deflection angle: The maximum deflection angle shall not be less than 7.5°.

[0118] (4) Resonant frequency: The single-axis resonance frequency is 600-800 Hz.

[0119] (5) Resonant frequency: power consumption is less than or equal to 500mW.

[0120] Based on the above design requirements, the material of the metal galvanometer mirror selected in this embodiment is titanium-copper alloy, and the yield strength of the material is 550 MPa. The following is a design analysis of a large-mirror metal micromirror based on titanium alloy material.

[0121] When the uniaxial metal micromirror is working, the metal micromirror system can be simplified into a single-degree-of-freedom torsion system, and its motion equation is:

[0122]

[0123] Where I is the moment of inertia of the system, c is the damping coefficient of the system, k is the stiffness coefficient of the system, and M is the electromagnetic torque acting on the micromirror system.

[0124] Considering that the movable part of the micromirror system includes the driving coil, titanium alloy reed and silicon reflective mirror, the moment of inertia of the system can be written as:

[0125]

[0126] Among them, ρ s , R s and t s represents the density, radius and thickness of the silicon reflector, ρ m , R m and t m represents the density, radius and thickness stiffness coefficient of the titanium alloy reed, ρ c , R c1 , R c2 and t c Indicates the density, inner radius, outer radius and thickness of the coil.

[0127] When the support beam of the micromirror adopts a straight beam design, the stiffness coefficient k of the micromirror system is as follows:

[0128]

[0129] Among them, w, h, l are the width, height and length of the torsion axis, G yx and G yz is the anisotropic shear modulus of the material.

[0130] The designed metal micromirror works at its resonant frequency, which can be expressed as

[0131]

[0132] Without considering the nonlinearity of the micromirror system, it can be deduced that the rotation angle of the micromirror in the resonant state is:

[0133]

[0134] in, is the damping ratio, and M is the torque acting on the micromirror system.

[0135] It can be calculated from formula 2, formula 3 and formula 4 above that the thickness of the folded beam can achieve the best effect in the range of 0.2-0.6mm while meeting the resonant frequency requirement of greater than 600.

[0136] Based on the thickness range of the folding beam deduced from the above formula, the applicant further conducted experiments near the above thickness range and determined that a better effect can be achieved when the thickness of the folding beam is between 0.1-2 mm.

[0137] The above describes a specific implementation method of the fast axis galvanometer module. The following will introduce the Figure 5-Figure 9 A driving detection module that cooperates with the fast-axis galvanometer module introduced in the embodiment.

[0138] See also Fig.10 , Fig.10 This is a schematic diagram of the structure of a drive detection module provided in an embodiment of the present application. Fig.10 As shown, the drive detection module 30 includes a magnet fixing frame 301 and a fast-axis drive magnet. The magnet fixing frame 301 is disposed below the fast-axis galvanometer module 10 and fixed on the support module 40. The fast-axis drive magnet is fixed on the magnet fixing frame 301.

[0139] The fast-axis drive magnet includes: a first boss magnet 302 and a second boss magnet 305. The first boss magnet 302 and the second boss magnet 305 are arranged in parallel below the fast-axis galvanometer module 10, and the magnetic field direction of the first boss magnet 302 is opposite to the magnetic field direction of the second boss magnet 303. In addition, the convex portion of the first boss magnet 302 and the convex portion of the second boss magnet 305 are inserted into the reed structure 102 to enhance the magnetic field around the above-mentioned fast-axis drive coil 103 during movement, ensure that the magnetic field intensity of the fast-axis drive coil 103 during movement changes little, greatly reduce the power consumption of the fast-axis drive coil 103 during the driving process, and ensure the driving linearity.

[0140] Specifically, a groove may be provided on the magnet holder 301, and the bottom of the first boss magnet 302 and the bottom of the second boss magnet 305 are respectively inserted into the groove of the magnet holder 301, and fixed to the magnet holder 301 by glue. In addition, hollow spaces are reserved on both sides of the leaf spring structure 102 of the fast-axis galvanometer module 10, so that the top of the first boss magnet 302 and the top of the second boss magnet 305 can be inserted into the leaf spring structure 102, thereby providing a sufficiently close magnetic field distribution for the fast-axis drive coil 103 on the leaf spring structure 102.

[0141] It should be noted that all components in the driving detection module 30 have no contact with the fast-axis galvanometer module 10, and there is a certain gap between the top of the driving detection module 30 and the bottom of the fast-axis galvanometer module 10, so that the driving detection module can move in the slow-axis direction without being blocked by the driving detection module 30.

[0142] Specifically, Fig.10 As shown, a fast-axis connection frame 306 is also provided between the driving detection module 30 and the fast-axis galvanometer module 10. The leaf spring structure 102 in the fast-axis galvanometer module 10 is fixed to the fast-axis connection frame 306 through the connection hole 110. One side of the fast-axis connection frame 306 is connected to the rotating shaft of the slow-axis driving module 20, and is used to rotate in the slow-axis direction under the drive of the rotating shaft of the slow-axis driving module 20; a rolling bearing 307 is provided on the other side of the fast-axis connection frame 306, and the rolling bearing 307 is arranged on the bearing hole on the right side of the support module 40, and the sliding friction between the operating shaft and the shaft seat (i.e., the support module 40) is converted into rolling friction, thereby reducing friction loss.

[0143] Optionally, the fast-axis drive magnet may further include a first magnetic material 303 and a second magnetic material 304, which are arranged in parallel between the first boss magnet 302 and the second boss magnet 305, and are used to optimize the magnetic field distribution of the first boss magnet 302 and the second boss magnet 303, that is, to ensure that the direction of the magnetic field distribution is as close as possible to the fast-axis drive coil 103, thereby providing a sufficiently large Lorentz force for the fast-axis drive coil 103. Exemplarily, the first magnetic material 303 may include a first cylindrical magnet, the second magnetic material 304 may include a second cylindrical magnet, and the magnetic field direction of the first cylindrical magnet is opposite to the magnetic field direction of the second cylindrical magnet.

[0144] See also Fig.11 , Fig.11 This is a schematic diagram of the structure of a fast axis drive magnet provided in an embodiment of the present application. Fig.11 As shown, the fast axis drive magnet can be composed of two groups of magnets, and both groups of magnets are inserted into the magnet fixing frame 301 and fixed to the magnet fixing frame 301 by glue. The two groups of magnets can be divided into a left magnet pair and a right magnet pair. The left magnet pair includes a second boss magnet 305 and a second magnetic material 304, and the right magnet pair includes a first boss magnet 302 and a first magnetic material 303. The first magnetic material 303 and the second magnetic material 304 can be magnets or magnetizable magnetic materials, such as iron, steel and other metals, for enhancing the magnetic field. For example, in Fig.11 In the embodiment, the first magnetic material 303 and the second magnetic material 304 are both cylindrical magnets. In addition, the magnetic field direction of each magnet in the two sets of magnets is as follows: Fig.11 As shown, the magnetic field directions between two adjacent magnets are opposite, that is, the magnetic field directions of the first boss magnet 302 and the second boss magnet 305 are opposite, and the magnetic field directions of the first magnetic material 303 and the second magnetic material 304 are also opposite.

[0145] above Figure 5-Figure 11 An implementation method of the fast-axis galvanometer module and the drive detection module is introduced. Another implementation method of the fast-axis galvanometer module and the drive detection module will be introduced below.

[0146] See also Fig.12 , Fig.12A schematic structural diagram of another fast-axis galvanometer module provided in an embodiment of the present application. The fast-axis galvanometer module includes a large-diameter MEMS micromirror. The MEMS micromirror includes an external support frame 501, a fast-axis drive coil 502, a reflective mirror 503, a folded wiring beam 504, and a support beam 505, which are integrally formed using a MEMS process. In other words, the external support frame 501, the fast-axis drive coil 502, the reflective mirror 503, the folded wiring beam 504, and the support beam 505 are in the same plane and together constitute a one-dimensional MEMS micromirror. Among them, the reflective mirror 503 can be, for example, a gold-plated mirror.

[0147] The external support frame 501 is located at the outermost side, the fast axis drive coil 502 is located inside the external support frame 501, and the reflective mirror 503 is disposed inside the fast axis drive coil 502. Specifically, the external support frame 501, the fast axis drive coil 502, and the reflective mirror 503 can all be square in shape, the external support frame 501 surrounds the periphery of the fast axis drive coil 502, and the fast axis drive coil 502 surrounds the periphery of the reflective mirror 503.

[0148] In addition, the middle position of the fast axis drive coil 502 is connected to the support beam 505 through the folded wiring beam 504, and the support beam 505 is integrally formed with the external support frame 501. Moreover, the fast axis drive coil 502 can rotate around the support beam 505 in the fast axis direction based on the folded wiring beam 504.

[0149] When a sine wave signal with a similar resonant frequency is input to the fast-axis drive coil 502, a larger swing angle can be achieved around the support beam 505 at a lower power consumption. During the rotation of the fast-axis drive coil 502, the folded wiring beam reduces the torsional stress of the fast-axis drive coil during the torsion process through the folded structure, thereby improving the reliability of long-term movement. The support beam 505 provides support for the rotation of the fast-axis drive coil 502.

[0150] See also Fig.13 , Fig.13 A schematic diagram of coupling a MEMS micromirror with a slow axis drive module and a drive detection module provided in an embodiment of the present application. Fig.13 As shown, the fast-axis drive magnet in the drive detection module includes a plurality of magnets, and the plurality of magnets are inserted into the inside of the MEMS micromirror to form a uniform strong magnetic field near the fast-axis drive coil 502, ensuring that the magnetic field distribution of the fast-axis drive coil 502 is uniform during the movement. Fig.13In the fast axis driving magnet in the driving detection module, the left magnet pair and the right magnet pair are arranged on the left and right sides of the fast axis driving coil respectively, and the left magnet pair includes adjacent magnets 506 and magnets 507 with opposite magnetic field directions, and the right magnet pair includes adjacent magnets 508 and magnets 509 with opposite magnetic field directions. Specifically, Fig.13 The magnet arrangement shown is similar to Fig.11 The magnet arrangement described in the embodiment is similar, and the details can be referred to above. Fig.11 The description of the embodiments will not be repeated here.

[0151] In this solution, the MEMS micromirror manufactured by MEMS technology can better realize drive integration, and the fast-axis drive coil and the reflective mirror are both manufactured by MEMS technology. The silicon material used to make the reflective mirror has high rigidity, making it easier for the reflective mirror to achieve high-frequency resonance, and the mirror is light in weight and has low drive power consumption.

[0152] Based on the structure of the fast-axis galvanometer module and the drive detection module introduced in the above embodiments, an angle detection sensor can also be arranged in the drive detection module to detect the angle change information of the fast-axis galvanometer module in the slow axis direction and the fast axis direction, so as to facilitate more accurate control of the movement of the fast-axis galvanometer module in the slow axis direction and the fast axis direction.

[0153] Specifically, in this embodiment, in addition to the fast-axis driving magnet for driving the fast-axis galvanometer module, the driving detection module also includes: an angle detection sensor, which can be arranged on the support module, and the angle detection sensor is arranged close to the fast-axis galvanometer module, that is, the angle detection sensor is also not in contact with the fast-axis galvanometer module. During the movement of the fast-axis galvanometer module, the angle detection sensor is used to obtain the angle change information of the fast-axis galvanometer module in the slow axis direction and the fast axis direction.

[0154] For example, see Fig.14 and Fig.15 , Fig.14 A schematic diagram of the arrangement of an angle detection sensor on a drive detection module provided in an embodiment of the present application; Fig.15 This is a schematic diagram of the structure of an angle detection sensor provided in an embodiment of the present application. Fig.14 As shown, the angle detection sensor 308 can be arranged above the magnet fixing frame 301 of the driving detection module. In addition, the angle detection sensor 308 is arranged directly below the reflective mirror surface 101 , and the angle detection sensor 308 does not contact the reed structure 102 .

[0155] like Fig.15As shown, the angle detection sensor 308 includes: a light source 310 and a photodetector array 311. The light source 310 may be a vertical-cavity surface-emitting laser (VCESL), a light-emitting diode (LED) or other light sources, which are used to emit a light beam to the fast-axis galvanometer module above, and the light intensity distribution of the light beam sent by the light source 310 is Gaussian. The photodetector array 311 may be an array detector composed of multiple detectors such as a photoelectric detector (PD), which is used to detect the light beam reflected back by the fast-axis galvanometer module.

[0156] Specifically, during the operation of the angle detection sensor, the light source 310 emits an angled light beam to the fast-axis galvanometer module; after the light beam emitted by the light source 310 is reflected by the fast-axis galvanometer module, the light beam reflected back by the fast-axis galvanometer module is received by the photodetector array and the intensity of the reflected light beam is detected. Since the light intensity characteristic of the light source is Gaussian distributed, the intensity of the light beam received by the detectors at different positions in the photodetector array is different. Fig.16 , Fig.16 The schematic diagram of the working principle of the angle sensor provided in the embodiment of the present application is as follows. Fig.16 As shown in the figure, when the reflective mirror on the fast axis galvanometer module rotates, the light intensity area and the received light intensity on each photodetector will change, so the output signal of the photodetector will also change. In this way, based on the relationship between the light intensity change of the photodetector and the rotation angle of the reflective mirror, the rotation angle of the reflective mirror can be determined by calculating the output signal of each photodetector.

[0157] In this solution, two-dimensional angle detection is achieved through the cooperation of a light source and an optical detector, which can ensure that the angle detection sensor has high working stability while being small in size, can adapt to various working environments and achieve high-precision detection.

[0158] Specifically, most of the related technologies use Hall sensors to detect the angle change of an object, and the Hall sensor is a magnetic sensor made using the Hall effect, which essentially uses the relationship between the magnetic field and the induced voltage in the semiconductor to measure the angle change of the object. That is, the Hall sensor usually requires a magnet and a semiconductor to cooperate, and the magnet is installed on the moving object, and then the movement angle of the object (i.e., the movement angle of the magnet) is measured by measuring the change in the induced voltage of the semiconductor. In the optical scanning device provided in this embodiment, if a Hall sensor is used to detect the angle of the reflective mirror surface, it is necessary to install a magnet on the fast-axis galvanometer module, which increases the load of the slow-axis drive module, and because the fast-axis galvanometer module itself is driven by the fast-axis drive magnet, the Hall sensor is easily affected by the original magnetic field, reducing the working stability and detection accuracy. Therefore, in this scheme, a light source and an optical detector that only need to be arranged on the drive detection module are used to realize the angle detection of the reflective mirror surface. On the one hand, it can not increase the load of the slow-axis drive module, and on the other hand, it will not be affected by the original magnetic field environment, ensuring working stability and detection accuracy. Moreover, in this solution, the number of photodetector arrays and the divergence angle of the light source can be adjusted to adapt to detection requirements of different accuracies and different angle ranges, and the solution is more versatile.

[0159] Optional, such as Fig.15 As shown, the angle detection sensor 308 may also include: a packaging substrate 312 and a sensor driving board 313. The light source 310 and the photodetector array 311 are mounted on the packaging substrate 312, and the packaging substrate 312 is arranged with conductive pins and circuits for powering and driving the light source 310 and the photodetector array 311 and collecting signals. The packaging substrate 312 is fixed on the sensor driving board 313, and the packaging substrate 312 is electrically connected to the relevant components of the sensor driving board 313 through wire bonding. The sensor driving board 313 is used to drive the light source and the photodetector array 311 to work through the packaging substrate 312, that is, to drive the light source 310 to work and provide a signal amplification function for the photodetector array 311.

[0160] In this solution, by mounting the light source and the photodetector array onto a packaging substrate and then achieving electrical connection with the sensor driver board through the packaging substrate, it is no longer necessary to pre-package the light source and the photodetector array and then mount them onto the sensor driver board, and the assembly of the angle detection sensor can be achieved at a lower cost.

[0161] Optionally, in order to ensure that the angle detection sensor can achieve high-precision and wide-angle range detection, the scale of the photodetector array can be greater than or equal to 2*2, for example, the scale of the photodetector array is 2*2 or 4*4. The specific layout of the scale of the photodetector array can be determined according to the actual application scenario, and this embodiment does not make any specific limitations on this.

[0162] The fast-axis galvanometer module and the drive detection module provided in this embodiment are introduced above. The specific structure of the slow-axis drive module provided in this embodiment will be introduced below.

[0163] In this embodiment, the slow axis driving module can also be driven by a voice coil motor structure, ensuring that the slow axis driving module can drive the fast axis galvanometer module with a simple structure. Fig.17 , Fig.17 This is a schematic diagram of the structure of a slow axis drive module provided in an embodiment of the present application. Fig.17 As shown, the slow axis driving module 20 includes: a motor housing 201, a slow axis driving coil 202, an arc core 203, an arc magnet 204, and a rotating shaft 205. The slow axis driving coil 202, the arc core 203, the arc magnet 204, and the rotating shaft 205 are all arranged in the motor housing 201.

[0164] The arc magnet 204 is fixed to one side of the rotating shaft 205, and the other side of the rotating shaft 205 is mechanically connected to the fast-axis galvanometer module. Specifically, one side of the rotating shaft 205 can be fixed to the arc magnet 204 by glue, and the other side of the rotating shaft 205 is mechanically connected to the fast-axis galvanometer module through the rotating shaft hole on the motor housing 201. In addition, the rotating shaft 205 can be connected to the rotating shaft hole on the motor housing 201 through a bearing. The arc magnet 204 and the arc core 203 are located in the same horizontal plane, and the arc magnet 204 and the arc core 203 are concentric arcs. For example, the arc magnet 204 and the arc core 203 are both arcs with the rotating shaft 205 as the center.

[0165] In addition, the arc core 203 can be arranged outside the arc magnet 204, and the arc core 203 can surround the arc magnet 204 on the outside. The slow axis driving coil 202 is wound on the arc core 203, so when the slow axis driving coil 202 is powered, the slow axis driving coil 202 wound on the arc core 203 will generate a strong magnetic field, so that the arc magnet 204 drives the rotating shaft 205 to swing back and forth in the slow axis direction under the magnetic force of the strong magnetic field.

[0166] See also Fig.18 , Fig.18 Schematic diagram of magnetic field distribution inside the slow axis drive module provided in the embodiment of the present application. Fig.18 As shown, based on Fig.17The arc structure of the arc core 203 shown in the figure, the magnetic field distribution corresponding to the arc core 203 is symmetrical in the center, so that the arc magnet 204 can generate a certain restoring force during the back and forth swinging process, thereby improving and reducing the power consumption of the back and forth swinging. In addition, the arc-shaped magnet and coil can effectively reduce the volume of the drive structure and reduce the load of the slow axis drive module itself, so that the slow axis drive module has the advantages of simple structure, small volume and fast response. In addition, Fig.17 The slow-axis drive module shown in the figure actually drives the rotating shaft to move by the arc magnet rather than the slow-axis drive coil, that is, the slow-axis drive coil is wound on a fixed arc-shaped iron core. Therefore, there is no need to consider the power supply and movement stability of the coil during movement, which can greatly improve the reliability and stability of the slow-axis drive structure.

[0167] In general, the optical scanner provided in this embodiment adopts a fast axis and a slow axis drive structure separation design, and through mechanical connection, it simultaneously realizes the requirements of large aperture (can realize 20-30mm aperture) and fast scanning (greater than 500Hz), and solves the long distance measurement and high resolution requirements of laser radar. In addition, the two drive axes (fast axis and slow axis) are compounded in space (ie, in the same plane) and fixedly connected by a support module, which can realize the small volume requirement.

[0168] The above describes the specific structure of the optical scanning device provided by this embodiment. The following describes the driving control process of the optical scanning device. Fig.19 , Fig.19 A schematic diagram of a drive control process of an optical scanning device provided in an embodiment of the present application.

[0169] like Fig.19 As shown in the figure, in order to realize the drive control of the optical scanning device, 4 ADCs, 2 DACs and 1 comparator can be used. Among them, 2 ADCs respectively collect the angle feedback information of the fast-axis and slow-axis piezoresistors, and the other 2 ADCs respectively detect the driving current to determine whether the driving coil of the MEMS is abnormal. Optionally, the temperature of the MEMS micromirror can be collected by 1 ADC, and the temperature compensation coefficient of the piezoresistors can be found in the chip. In addition, 1 comparator input signal is used for the fast-axis control algorithm; the 4 DACs are divided into 2 groups of pseudo-differentials to complete the drive output of the fast axis and the slow axis respectively.

[0170] The drive control of the optical scanning device mainly includes fast-axis feedback control and slow-axis feedback control. Fast-axis feedback control refers to the optical feedback output signal being amplified by an operational amplifier, finding its resonant frequency point through a zero comparator, and locking the fast-axis frequency and phase through phase-locked control, so that the fast axis works in a resonant state; at the same time, in order to ensure the stability of the fast-axis angle, it is necessary to collect the fast-axis angle through an ADC and adjust the drive voltage through closed-loop control to ensure that the phase and amplitude of the fast axis meet the requirements. In addition, when the fast-axis angle deviates and cannot be compensated and corrected, a fault mechanism can be triggered.

[0171] Since the slow axis is driven by a linear sawtooth wave, there is no need to phase-lock or frequency-lock the slow axis. It only needs to ensure that the angle error meets the requirements. Therefore, the slow axis feedback angle is directly collected through the ADC after the operational amplifier, and the driving voltage is adjusted through closed-loop control. At the same time, when the slow axis angle deviates and cannot be compensated or corrected, a fault mechanism can be triggered.

[0172] In addition, in order to achieve a more uniform pattern scanned by the optical scanner, the fast axis and slow axis drive signals need to be synchronized. Fig. 20 , Fig. 20 Schematic diagram of the driving waveform of the optical scanner provided in the embodiment of the present application. Fig. 20 As shown, the fast-axis scanning waveform is actually a sine waveform with a higher frequency, and the slow-axis scanning waveform is a linear sawtooth wave with a lower frequency. Finally, the waveform obtained by scanning the reflective mirror under the drive of the slow axis and the fast axis is a grating shape.

[0173] In addition, an embodiment of the present application also provides a laser radar system, which includes the optical scanning device introduced in the above embodiment.

[0174] The above describes the embodiments of the present application in detail. The steps in the method of the embodiments of the present application can be scheduled in sequence, merged or deleted according to actual needs; the modules in the device of the embodiments of the present application can be divided, merged or deleted according to actual needs.

[0175] It should be understood that "one embodiment" or "an embodiment" mentioned throughout the specification means that specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present application. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It should be understood that in various embodiments of the present application, the size of the sequence number of the above-mentioned processes does not mean the order of execution, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present application.

Claims

1. An optical scanning device, characterized in that: include: A slow-axis driving module, a fast-axis galvanometer module, a driving detection module and a supporting module, wherein the fast-axis galvanometer module includes a reflecting mirror for reflecting laser light, and the driving detection module includes a fast-axis driving magnet; The slow axis driving module is mechanically connected to the fast axis galvanometer module, and is used to drive the fast axis galvanometer module in the slow axis direction; The fast-axis driving magnet is arranged close to the fast-axis galvanometer module and is used to drive the reflective mirror surface in the fast-axis galvanometer module in the fast-axis direction; The supporting module is used to fix the driving detection module.

2. The device according to claim 1, characterized in that The fast-axis galvanometer module further includes: a fast-axis drive coil and an external support frame; The fast axis drive coil and the reflective mirror are both arranged in the external support frame, and the fast axis drive coil is used to drive the reflective mirror to rotate relative to the external support frame in the fast axis direction under the magnetic force of the fast axis drive magnet; The external support frame is mechanically connected to the slow axis driving module, and is used to drive the fast axis driving coil and the reflective mirror to rotate in the slow axis direction under the drive of the slow axis driving module.

3. The device according to claim 2, characterized in that The fast-axis galvanometer module further includes: a reed structure; The reflective mirror is arranged on the front side of the reed structure, the fast axis drive coil is arranged on the back side of the reed structure, and the area of ​​the reed structure used for arranging the reflective mirror and the fast axis drive coil can be deformed in the fast axis direction; The leaf spring structure comprises: a folding beam and the external support frame in the same plane, and the folding beam is connected to the external support frame; The folded beam can be deformed relative to the external support frame in the fast axis direction, so as to provide a restoring force for the reflective mirror surface when performing resonant motion.

4. The device according to claim 3, characterized in that The thickness of the folding beam is 0.1 mm-2 mm.

5. The device according to claim 4, characterized in that The leaf spring structure further comprises a mirror support frame, the mirror support frame is connected to the folding beam, and the reflective mirror is arranged on the mirror support frame; The mirror support frame is in a cross shape or a cross shape.

6. The device according to any one of claims 3 to 5, characterized in that: The fast axis drive magnet comprises: A first boss magnet and a second boss magnet, wherein the magnetic field direction of the first boss magnet is opposite to the magnetic field direction of the second boss magnet; The raised portion of the first boss magnet and the raised portion of the second boss magnet are inserted into the leaf spring structure to enhance the magnetic field around the fast axis drive coil during movement.

7. The device according to claim 6, characterized in that The fast axis drive magnet also includes: a first magnetic material and a second magnetic material; The first magnetic material and the second magnetic material are arranged between the first boss magnet and the second boss magnet to optimize the magnetic field distribution of the first boss magnet and the second boss magnet.

8. The device according to claim 7, characterized in that The first magnetic material includes a first cylindrical magnet, the second magnetic material includes a second cylindrical magnet, and a magnetic field direction of the first cylindrical magnet is opposite to a magnetic field direction of the second cylindrical magnet.

9. The device according to claim 2, characterized in that The fast-axis galvanometer module includes: a micro-electromechanical system MEMS micro-mirror; The MEMS micromirror includes the integrally formed reflective mirror surface, the fast axis drive coil and the external support frame.

10. The device according to claim 9, characterized in that The MEMS micromirror further comprises: Folding routing beams and support beams; The fast axis drive coil is connected to the support beam through the folded wiring beam, and the fast axis drive coil rotates around the support beam in the fast axis direction; The folded routing beam is used to reduce the torsional stress of the fast axis drive coil during the torsion process; The support beam is used to provide support for the rotation of the fast axis drive coil.

11. The device according to claim 9 or 10, characterized in that The fast axis drive magnet comprises: At least two magnets, wherein the magnetic fields of the at least two magnets are in opposite directions; The at least two magnets are inserted into the fast axis drive coil to enhance the magnetic field around the fast axis drive coil during movement.

12. The device according to any one of claims 1 to 11, characterized in that The slow axis driving module comprises: A rotating shaft, an arc-shaped magnet, an arc-shaped iron core and a slow-axis driving coil, wherein the arc-shaped magnet and the arc-shaped iron core are located in the same horizontal plane, and the arc-shaped magnet and the arc-shaped iron core are concentric arcs; The arc magnet is fixed to one side of the rotating shaft, the other side of the rotating shaft is mechanically connected to the fast-axis galvanometer module, and the slow-axis driving coil is wound on the arc iron core; When the slow axis driving coil is energized, the arc-shaped magnet drives the rotating shaft to swing back and forth in the slow axis direction under the action of magnetic force.

13. The device according to any one of claims 1 to 12, characterized in that The drive detection module also includes: An angle detection sensor, wherein the angle detection sensor is arranged on the support module, and the angle detection sensor is arranged close to the fast-axis galvanometer module; The angle detection sensor is used to obtain the angle change information of the fast-axis galvanometer module in the slow-axis direction and the fast-axis direction.

14. The device according to claim 13, characterized in that The angle detection sensor comprises: a light source and a photodetector array; The light source is used to emit a first light beam with an angle to the fast-axis galvanometer module; The photodetector array is used to receive the second light beam reflected by the fast-axis galvanometer module and detect the intensity of the second light beam.

15. The device according to claim 14, characterized in that The angle detection sensor further comprises: a packaging substrate and a sensor driving board; The light source and the photodetector array are mounted on the packaging substrate, the packaging substrate is fixed on the sensor driving board, and the packaging substrate is electrically connected to the sensor driving board. The sensor driving board is used to drive the light source and the photodetector array to work through the packaging substrate.

16. The device according to claim 14 or 15, characterized in that The size of the photodetector array is greater than or equal to 2*2.

17. A laser radar system, characterized in that: Comprising the optical scanning device as claimed in any one of claims 1-16.

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