Patent Publication Number: US-2023161003-A1

Title: Lidar device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2020-0046050, filed on Apr. 16, 2020, the disclosure of which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present invention relates to a LIDAR device, and more specifically to a LIDAR device including a laser emitting/receiving module and a scanner having a polygon mirror on a rotating body. 
     BACKGROUND ART 
     Recently, LIDAR (Light Detection And Ranging), which is a laser radar device, has been widely used to detect surrounding terrain or objects in automobiles, mobile robots or the like. 
     The LIDAR device emits pulsed laser light into the atmosphere and uses a reflector or scatterer to measure the distance, object or atmospheric phenomenon, and it calculates the time of reflected light as a clock pulse and has a resolution of 5 m at the frequency of 30 MHz and a resolution of 1 m at the frequency of 150 MHz. The LIDAR device irradiates laser light into the surrounding area and uses the time and intensity of the reflected light which is reflected off the surrounding object or terrain to measure the distance, speed and shape of a measurement target, or to precisely measure the surrounding object or terrain. 
     Since the conventional LIDAR device emits a laser with a wide beam width corresponding to the angle of view and simultaneously acquires reflected light from all directions within the angle of view to obtain a distance from the reflector, a laser module having a very high power output is required, and accordingly, there is a problem in that the size is large and the price is high. 
     In addition, most of the LIDAR devices having the panoramic scanning function are configured to rotate the entire device including the transmission optical system and the reception optical system. However, if the entire device is rotated, the size of the system becomes larger, which further exacerbates the problems of price and power consumption increases. 
     Meanwhile, since a LIDAR device used in a vehicle or the like irradiates a laser toward a person, it is required to secure safety associated with the human body, particularly the eyes. Satisfying such safety requirements while minimizing the deterioration of detection performance is emerging as a task related to LIDAR. 
     (Patent Document) Korean Patent Application No. 10-2015-0061330 “LIDAR SENSOR SYSTEM”, published on Jun. 4, 2015 
     DISCLOSURE 
     Technical Problem 
     The present invention has been devised to solve the problems of prior art described above, and an object of the present invention is to provide a LIDAR device which is capable of effectively increasing performance such as vertical resolution and the like. 
     In addition, another object of the present invention is to provide a LIDAR device that improves the detection performance and also ensures safety for the human body. 
     Technical Solution 
     According to an aspect of the present invention, provided is a LIDAR device, including a laser unit; and a scanner unit, wherein the laser unit includes a first laser module for emitting and receiving a laser in a first direction; and a second laser module, disposed in a stacked form with the first laser module, for emitting and receiving a laser in a second direction, and wherein the scanner unit includes a first polygon mirror which is rotated and has a plurality of mirrors which reflect the laser emitted from the first laser module and the laser received by the first laser module; and a second polygon mirror which is disposed in a stacked form with the first polygon mirror and rotated integrally with the first polygon mirror, and has a plurality of mirrors which reflect the laser emitted from the second laser module and the laser received by the second laser module. 
     In this case, the first laser module may be disposed above the second laser module. 
     In addition, the first laser module may have a higher laser output than the second laser module. 
     In addition, the first laser module may include a laser light source with a higher power output than the second laser module. 
     In addition, the first laser module may include a plurality of laser light sources compared to the second laser module. 
     In addition, the first laser module may have a higher laser reception sensitivity than the second laser module. 
     In addition, the first laser module may have a wider optical entrance than the second laser module. 
     In addition, the first laser module may include a detector with multiple channels compared to the second laser module. 
     In addition, a plurality of polygon mirrors provided in the first polygon mirror may be arranged to have different inclination angles with respect to the vertical direction, and a plurality of polygon mirrors provided in the second polygon mirror may be arranged to have different inclination angles with respect to the vertical direction. 
     In addition, a plurality of polygon mirrors provided in the first polygon mirror may be arranged such that the inclination angle with respect to the vertical direction is gradually decreased or increased in the rotation direction, and a plurality of polygon mirrors provided in the second polygon mirror may be arranged such that the inclination angle with respect to the vertical direction is gradually decreased or increased in the rotation direction. 
     Advantageous Effects 
     According to an exemplary embodiment of the present invention, it is possible to efficiently improve the vertical resolution of the LIDAR device through a scanner unit that is provided with polygon mirrors which are disposed to be stacked and rotated integrally. 
     In addition, according to an exemplary embodiment of the present invention, by configuring any one or more of the laser output and reception sensitivity of the laser module arranged in multiple layers differently, it is possible to simultaneously achieve the safety of the LIDAR device on the human body and the improvement of the detection performance. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG.  1    is a diagram showing the LIDAR device according to an exemplary embodiment of the present invention. 
         FIG.  2    is a plan view of the LIDAR device according to an exemplary embodiment of the present invention. 
         FIG.  3    is a cross-sectional view A-A′ of the scanner unit of the LIDAR device according to an exemplary embodiment of the present invention. 
         FIG.  4    is a cross-sectional view B-B′ of the scanner unit of the LIDAR device according to an exemplary embodiment of the present invention. 
         FIG.  5    is a diagram showing vertical channels of the LIDAR device according to an exemplary embodiment of the present invention. 
         FIG.  6    is a diagram showing vertical channels implemented by the LIDAR device according to another exemplary embodiment of the present invention. 
         FIG.  7    is a view showing the LIDAR device according to another exemplary embodiment of the present invention. 
     
    
    
     MODES OF THE INVENTION 
     Hereinafter, with reference to the accompanying drawings, the exemplary embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily practice the present invention. The present invention may be embodied in many different forms and is not limited to the exemplary embodiments described herein. In order to clearly describe the present invention, parts that are irrelevant to the description are omitted from the drawings, and the same reference numerals are assigned to the same or similar components throughout the specification. 
     In the present specification, terms such as “include” or “have” are intended to designate that a feature, number, step, operation, component, part or combination thereof described in the specification exists, but it should be understood that it does not preclude the possibility of addition or existence of one or more other features or numbers, steps, operations, components, parts or combinations thereof. 
       FIG.  1    is a diagram showing the LIDAR device according to an exemplary embodiment of the present invention. In addition,  FIG.  2    is a plan view of the LIDAR device according to an exemplary embodiment of the present invention. 
     Referring to  FIGS.  1  and  2   , the LIDAR device according to an exemplary embodiment of the present invention includes a laser unit  10  and a scanner unit  20 . 
     In the LIDAR device according to an exemplary embodiment of the present invention, the laser unit  10  is fixedly arranged, and the scanner unit  20  is spaced apart from the laser unit  10  and rotatably arranged about a rotational axis penetrating in the vertical direction. In this case, the rotational axis may be formed while passing through the center of the scanner unit  20 . The laser emitted through the laser unit  10  is reflected by the scanner unit  20  and travels to the outside, and the laser reflected by an external object and returned to the scanner unit  20  is reflected by the scanner unit  20  and returns to the laser unit  10 . 
     The laser unit  10  includes a first laser module  11  and a second laser module  12 . The first laser module  11  emits and receives a laser in a first direction. In addition, the second laser module  12  is disposed in a stacked form with the first laser module  11  to emit and receive a laser in a second direction. In this case, the second direction may be formed parallel to the first direction. 
     More specifically, in an exemplary embodiment of the present invention, the first laser module  11  is disposed above the second laser module  12 . Correspondingly, the first polygon mirror  21  viewed from the back is disposed above the second polygon mirror  22 . 
     In an exemplary embodiment of the present invention, the first laser module  11  includes a first laser light source  111  and a first laser detector  112 . In addition, the second laser module  12  includes a second laser light source  121  and a second laser detector  122 . 
     As such, in an exemplary embodiment of the present invention, the first laser module  11  and the second laser module  12  respectively include a pair of light sources and detectors, but as will be described below, in another exemplary embodiment of the present invention, the combination of the light sources and the detectors may be different such that the first laser module  11  and the second laser module  12  have different laser outputs or reception sensitivities, respectively. 
     Meanwhile, although omitted for the brevity of description, the first laser module  11  and the second laser module  12  may additionally include an optical system such as a lens or the like, which is required in the process of emitting and receiving by a laser light source, respectively. 
     The scanner unit  20  includes a first polygon mirror  21  and a second polygon mirror  22 . In an exemplary embodiment of the present invention, the first polygon mirror  21  and the second polygon mirror  22  are stacked and formed vertically symmetrically with respect to a horizontal plane. 
     The first polygon mirror  21  is disposed in front of the first laser module  11  and includes and rotates a plurality of mirrors that reflect a laser emitted from the first laser module  11  and a laser received by the first laser module  11 . A plurality of mirrors provided in the first polygon mirror  21  may have different inclination angles with respect to the vertical direction. 
     In an exemplary embodiment of the present invention, the first polygon mirror  21  is formed in four surfaces and includes a total of four mirrors such as a 1-1 mirror  211 , a 1-2 mirror  212 , a 1-3 mirror  213  and a 1-4 mirror  214 . 
     According to an exemplary embodiment of the present invention, the number of mirrors of the polygon mirror is not limited, and the number may be increased or decreased as necessary. 
     Meanwhile, in the first polygon mirror  21 , the inclination angles of the plurality of mirrors with respect to the vertical direction are gradually decreased or increased in the rotational direction. 
       FIG.  3    illustrates a cross-sectional view A-A′ of the scanner unit of the LIDAR device according to an exemplary embodiment of the present invention, and  FIG.  4    illustrates a cross-sectional view B-B′ of the scanner unit of the LIDAR device according to an exemplary embodiment of the present invention. 
     Referring to  FIGS.  3  and  4   , it can be confirmed that the inclination angle (θ 1 ) of the 1-1 mirror, the inclination angle (θ 2 ) of the 1-2 mirror  212 , the inclination angle (θ 3 ) of the 1-3 mirror  213  and the inclination angle (θ 4 ) of the 1-4 mirrors  214  with respect to the vertical direction are configured to increase gradually. 
     The second polygon mirror  22  is disposed in a stacked form with the first polygon mirror  21  and rotates integrally with the first polygon mirror  21 . As described above, the second polygon mirror  22  is disposed below the first polygon mirror  21 . The plurality of mirrors provided in the second polygon mirror  22  may have different inclination angles with respect to the vertical direction. 
     In an exemplary embodiment of the present invention, the second polygon mirror  22  includes a plurality of mirrors that reflect the laser emitted from the second laser module  12  and the laser received by the second laser module  12 , and it is configured such that the inclination angles of the plurality of mirrors with respect to the vertical direction are gradually decreased or increased in the rotational direction. 
     Specifically, in an exemplary embodiment of the present invention, the second polygon mirror  22  is symmetrical with the first polygon mirror  21  with respect to a horizontal plane. Accordingly, the second polygon mirror  22  includes a 2-1 mirror  221 , a 2-2 mirror  222 , a 2-3 mirror  223  and a 2-4 mirror  224 . 
     In addition, the inclination angle of the 2-1 mirror  221 , the inclination angle of the 2-2 mirror  222 , the inclination angle of the 2-3 mirror  223  and the inclination angle of the 2-4 mirror  224  with respect to the vertical direction are configured to increase gradually, and these angles respectively correspond to the inclination angle (θ 1 ) of the 1-1 mirror  211 , the inclination angle (θ 2 ) of the 1-2 mirror  212 , the inclination angle (θ 3 ) of the 1-3 mirror  213  and the inclination angle (θ 4 ) of the 1-4 mirrors  214  with respect to the vertical direction. 
       FIG.  5    is a diagram showing vertical channels of the LIDAR device according to an exemplary embodiment of the present invention. 
     As can be confirmed from  FIG.  5   , according to the LIDAR device according to an exemplary embodiment of the present invention, four vertical channels (Sa) are formed through the first polygon mirror  21  including the first laser module  11  and four mirrors having different inclined surfaces, and four vertical channels (Sb) are formed through the second polygon mirror  22  including the second laser module  12  and four mirrors having different inclined surfaces such that it is possible to effectively secure a total of 8 vertical channels. 
       FIG.  6    is a diagram showing vertical channels implemented by the LIDAR device according to another exemplary embodiment of the present invention. 
     Referring to  FIG.  6   , in the LIDAR device according to another exemplary embodiment of the present invention, the vertical channel (Sa) formed by the first laser module  11  and the first polygon mirror  21  may have a high power output or high sensitivity, and the vertical channel (Sb) formed by the second laser module  12  and the second polygon mirror  22  may have a relatively low power output or sensitivity. 
     In order to implement such different power outputs or reception sensitivities, in the LIDAR device according to another exemplary embodiment of the present invention, the first laser module  11  and the second laser module  12  have different laser outputs from each other or different laser reception sensitivities from each other. 
     When it is assumed that the LIDAR device according to another exemplary embodiment of the present invention is applied to a vehicle, the first laser module  11  is involved in the detection of the upper front side of the LIDAR device, and thus performs the detection of a vehicle and an object at a long distance. In addition, since the second laser module  12  is involved in the detection of the front lower side of the LIDAR device, it performs the detection of the near field and the ground. 
     In such a state, it is efficient for the first laser module  11  to have a relatively high laser output and reception sensitivity compared to the second laser module  12 . In addition, it is possible to secure the safety of the human body because the laser output is not excessively increased as a whole through the power outputs that are different up and down. 
     From this point of view, in another exemplary embodiment of the present invention, it can be assumed that the first laser module  11  is configured to have a higher laser output than the second laser module  12 . 
     Specifically, as shown in  FIG.  7   , the first laser module  11  may include a plurality of laser light sources compared to the second laser module  12 . Specifically, the first laser module  11  may include a 1-1 laser light source  111   a,  a 1-2 laser light source  111   b,  a 1-3 laser light source  111   c  and a 1-4 laser light source  111   d.  In this case, each laser light source may have the same power output. 
     For example, the 1-1 laser light source  111   a,  the 1-2 laser light source  111   b,  the 1-3 laser light source  111   c,  the 1-4 laser light source  111   d  and the second laser light source  121  may respectively have a power output of 75 W. 
     Meanwhile, the first laser module  11  may include a laser light source having a higher power output than the second laser module  12 . That is, the first laser module  11  and the second laser module  12  may include the same number of light sources, but the first laser light source  111  of the first laser module  11  may have a high power output, and the second laser module  12  of the second laser light source  121  may have a low power output. 
     For example, the first laser light source  111  may have a power output of 300 W, and the second laser light source  121  may have a power output of 75 W. 
     In addition, meanwhile, it may be assumed that the first laser module  11  and the second laser module  11  have different laser reception sensitivities. 
     Specifically, the first laser module  11  may have a higher laser reception sensitivity than the second laser module  12 . To this end, the first laser module  11  may have a wider optical entrance than the second laser module  12 , or the first laser module  11  may have a detector with multiple channels compared to the second laser module  12   
     For example, the first laser module  11  may have an optical entrance of 1,600 m 2  to be suitable for long-distance detection or may have a multi-channel array of 16 channels or more, and the second laser module  12  may have an optical entrance of 400 m 2  to be suitable for short-distance detection or may have a multi-channel array of 4 channels or less. 
     Although an exemplary embodiment of the present invention has been described, the spirit of the present invention is not limited by the exemplary embodiments presented herein, and those skilled in the art who understand the spirit of the present invention will be able to easily suggest other exemplary embodiments by modifying, changing, deleting or adding components within the scope of the same spirit, but this is also said to be within the scope of the present invention.