Patent Publication Number: US-2022221699-A1

Title: Double-telecentric projection lens and head-up display device mounted on automobile

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims priority to Chinese Patent Application No. 202110022840.8, filed before China National Intellectual Property Administration on Jan. 8, 2021 and entitled “DOUBLE-TELECENTRIC PROJECTION LENS AND HEAD-UP DISPLAY DEVICE MOUNTED ON AUTOMOBILE,” the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     Embodiments of the present disclosure relate to the technical field of projection optics, and in particular, relate to a double-telecentric projection lens and a head-up display device mounted on an automobile. 
     BACKGROUND 
     A head-up display (HUD) refers to a display mounted on a front windshield of an automobile. Nowadays, with transformation of the automobile towards intelligence, at present, newly designed intelligent automobiles are all mounted with HUDs, and drivers are capable of knowing speed, speed limitation signs, drive routes and the like vehicle information and road condition information with no need of lowering heads to check instrument panels. Augmented reality HUDs (AR HUDs) are prevailing currently. An AR HUD is a head-up display device capable of displaying AR pictures. 
     During practice of embodiments of the present disclosure, the applicant has found that the related art has at least the following problem: At present, the HUD, that is, the head-up display device, mounted on the automobile is only capable of displaying a two-dimensional planar picture, for example, a driving information picture of the automobile, or is only capable of displaying an AR picture, for example, a picture displaying road condition information captured by a camera of the automobile. Where these two pictures need to be simultaneously displayed, two head-up display devices are needed. 
     The embodiments of the present disclosure are intended to provide a projection optical system and a head-up display device mounted on an automobile, such that projection imaging of two pictures is achieved. To achieve this solution, a double-telecentric projection lens is designed in the embodiments of the present disclosure to achieve imaging by a single optical engine (single DMD chip) in combination with double optical lenses. In this way, a projection solution capable of achieving projection imaging of two pictures in the above solution is achieved. 
     SUMMARY 
     With respect to the defects in the related art, objects of embodiments of the present disclosure are to provide a double-telecentric projection lens, and a head-up display device mounted on an automobile. 
     The objects of the embodiments of the present disclosure are achieved by employing the following technical solutions: 
     To solve the above technical problem, in a first aspect, the embodiments of the present disclosure provide a double-telecentric projection lens applicable to a projection optical system in a head-up display device mounted on an automobile. The double-telecentric projection lens includes a front lens group, a rear lens group, and an equivalent prism that are successively arranged between an image side and a DMD chip; wherein 
     the front lens group includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens that are successively arranged, and the rear lens group includes a sixth lens, a seventh lens, an eighth lens, and a ninth lens that are successively arranged, wherein the third lens and the fourth lens constitute a double-cemented lens; and 
     the DMD chip is configured to simultaneously emit two images, wherein during simultaneous emission of the two images from the DMD chip, the simultaneously emitted two images are emitted from the double-telecentric projection lens and imaged at different positions. 
     In some embodiments, an image side of the first lens is a concave surface, and an object side of the first lens is a convex surface; 
     an image side of the second lens is a convex surface, and an object side of the second lens is a convex surface; 
     an image side of the third lens is a concave surface, and an object side of the third lens is a concave surface; 
     an image side of the fourth lens is a convex surface, and an object side of the fourth lens is a convex surface; 
     an image side of the fifth lens is a convex surface, and an object side of the fifth lens is a convex surface; 
     an image side of the sixth lens is a concave surface, and an object side of the sixth lens is a concave surface; 
     an image side of the seventh lens is a concave surface, and an object side of the seventh lens is a convex surface; 
     an image side of the eighth lens is a convex surface, and an object side of the eighth lens is a convex surface; and 
     an image side of the ninth lens is a convex surface, and an object side of the ninth lens is a concave surface. 
     In some embodiments, the equivalent prism is a turning prism and a right-angle triangular prism, wherein one right-angle surface of the right-angle triangular prism is opposite to a light exit surface of the DMD chip, the other right-angle surface of the right-angle triangular prism is opposite to a light incident side of the rear lens group, and an inclined surface of the right-angle triangular prism has a reflection angle of 90 degrees; and 
     an optical axis of the DMD chip is perpendicular to an optical axis of the front lens group and the rear lens group. 
     In some embodiments, the double-telecentric projection lens has a focal length of 90 mm, and the double-telecentric projection lens has a total length of 150 mm. 
     In some embodiments, the double-telecentric projection lens has a magnification of 1:1, and the double-telecentric projection lens has a relative aperture of 2. 
     To solve the above technical problem, in a second aspect, the embodiments of the present disclosure provide a head-up display device mounted on an automobile. The head-up display device includes a projection optical system capable of projecting a first image and a second image on a front windshield of the automobile such that imaging is achieved on the front windshield, wherein the projection optical system includes: 
     the double-telecentric projection lens according to the first aspect, wherein the double-telecentric projection lens is configured to simultaneously emit light beams of the first image and the second image; and 
     a light splitting device, wherein an optical center of the light splitting device is arranged on an image side of the double-telecentric projection lens, and a light incident side of the light splitting device is arranged to face a light exit side of the double-telecentric projection lens; 
     a first reflection unit, wherein a light incident side of the first reflection unit is arranged to face a first light reflection side of the light splitting device; 
     a first lens, wherein a light incident side of the first lens is arranged to face a light reflection side of the first reflection unit, and a light exit side of the first lens is configured to emit the first image; 
     a second reflection unit, wherein a light incident side of the second reflection unit is arranged to face a second light reflection side of the light splitting device; and 
     a second lens, wherein a light incident side of the second lens is arranged to face a light reflection side of the second reflection unit, and a light exit side of the second lens is configured to emit the second image. 
     In some embodiments, the light splitting device includes a first reflection structure and a second reflection structure; wherein the first reflection structure is configured to receive and reflect the light beam of the first image, the second reflection structure is configured to receive and reflect the light beam of the second image, a light reflection side of the first reflection structure is the first light reflection side of the light splitting device, and a light reflection side of the second reflection structure is the second light reflection side of the light splitting device. 
     In some embodiments, the first reflection structure and the second reflection structure are both a mirror. 
     In some embodiments, the first reflection structure and the second reflection structure are both a combination of a mirror, and a filter, a highly reflective film and/or an anti-reflection lens. 
     In some embodiments, the first reflection unit and the second reflection unit are both a mirror. 
     As compared with the related art, the present disclosure achieves the following beneficial effects: The embodiments of the present disclosure provide a double-telecentric projection lens. The double-telecentric projection lens includes a front lens group, a rear lens group, and an equivalent prism that are successively arranged between an image side and a DMD chip; wherein the front lens group includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens that are successively arranged, and the rear lens group includes a sixth lens, a seventh lens, an eighth lens, and a ninth lens that are successively arranged, wherein the third lens and the fourth lens constitute a double-cemented lens; and the DMD chip is configured to simultaneously emit two images, wherein during simultaneous emission of the two images from the DMD chip, the simultaneously emitted two images are emitted from the double-telecentric projection lens and imaged at different positions. The double-telecentric projection lens according to the embodiments of the present disclosure is applicable to the projection optical system in the head-up display device mounted on an automobile such that simultaneous projection imaging of two pictures is achieved, and the imaging effect is good. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       One or more embodiments are illustrated by way of example, and not by limitation, in the figures of the accompanying drawings, wherein elements/modules having the same reference numeral designations represent like elements/modules throughout. The drawings are not to scale, unless otherwise disclosed. 
         FIG. 1  is a schematic diagram of an application scenario of a double-telecentric projection lens according to an embodiment of the present disclosure; 
         FIG. 2  is a schematic diagram of imaging on a front windshield in the application scenario in  FIG. 1 ; 
         FIG. 3  is a schematic diagram of an optical path of a double-telecentric projection lens according to a first embodiment of the present disclosure; 
         FIG. 4  is a schematic diagram of a partial structure of the double-telecentric projection lens in  FIG. 3 ; 
         FIG. 5  is a schematic diagram of a partial structure of a double-telecentric projection lens according to the first embodiment of the present disclosure; 
         FIG. 6  is a schematic diagram of full field transfer function (MTF) values of the double-telecentric projection lens in  FIG. 3 ; 
         FIG. 7  is a schematic diagram of field curvature and distortion of a full field and full wave-band of the double-telecentric projection lens in  FIG. 3 ; 
         FIG. 8  is a schematic diagram of vertical chromatic aberration of a full field and full wave-band of the double-telecentric projection lens in  FIG. 3 ; 
         FIG. 9  is a schematic diagram of dot columns of a full field of the double-telecentric projection lens in  FIG. 3 ; 
         FIG. 10  is a schematic diagram of hardware structure of a head-up display device mounted on an automobile according to a second embodiment of the present disclosure; and 
         FIG. 11  is a schematic structural diagram of an optical path of a projection optical system in the head-up display device mounted on an automobile in  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure is further described with reference to some exemplary embodiments. The embodiments hereinafter facilitate further understanding of the present disclosure for a person skilled in the art, rather than causing any limitation to the present disclosure. It should be noted that persons of ordinary skill in the art may derive various variations and modifications without departing from the inventive concept of the present disclosure. Such variations and modifications shall pertain to the protection scope of the present disclosure. 
     For clearer descriptions of the objectives, technical solutions, and advantages of the present disclosure, the present disclosure is further described with reference to specific embodiments and attached drawings. It should be understood that the specific embodiments described herein are only intended to explain the present disclosure instead of limiting the present disclosure. 
     It should be noted that, in the absence of conflict, embodiments of the present disclosure and features in the embodiments may be incorporated, which all fall within the protection scope of the present disclosure. In addition, although function module division is illustrated in the schematic diagrams of apparatuses, and in some occasions, module division different from the divisions of the modules in the apparatuses may be used. Further, the terms “first,” “second,” and the like used in this text do not limit data and execution sequences, and are intended to distinguish identical items or similar items having substantially the same functions and effects. 
     For ease of definition of the connection structure, positions of the components are defined using a light exit direction of a light beam as a reference. As used herein, the terms “upper,” “lower,” “left,” “right,” “vertical” “horizontal,” and the like expressions are used for illustration purposes only. For ease of definition of the connection structure, positions of the components are defined using a light exit direction of a light beam as a reference. 
     Unless the context clearly requires otherwise, throughout the specification and the claims, technical and scientific terms used herein denote the meaning as commonly understood by a person skilled in the art. Additionally, the terms used in the specification of the present disclosure are merely for description of the embodiments of the present disclosure, but are not intended to limit the present disclosure. As used herein, the term “and/or” in reference to a list of one or more items covers all of the following interpretations of the term: any of the items in the list, all of the items in the list and any combination of the items in the list. 
     In addition, technical features involved in various embodiments of the present disclosure described hereinafter may be combined as long as these technical features are not in conflict. 
     In view of the case where the conventional head-up display device mounted on an automobile is only capable of displaying an image, but incapable of simultaneously displaying a close-up image and a distal image, and/or the case a two-dimensional image and a three-dimensional image need to be simultaneously displayed, embodiments of the present disclosure provide a double-telecentric projection lens. In the double-telecentric projection lens, a DMD chip is configured to simultaneously emit two images, wherein during simultaneous emission of the two images from the DMD chip, the simultaneously emitted two images are emitted from the double-telecentric projection lens and imaged at different positions. In this way, different contents and pictures are respectively displayed at two different positions. In addition, the double-telecentric projection lens according to the embodiments of the present disclosure has advantages of good imaging effect and small size. 
       FIG. 1  is a schematic diagram of an application scenario of a double-telecentric projection lens according to an embodiment of the present disclosure, and  FIG. 2  is a schematic diagram of imaging on a front windshield in the application scenario in  FIG. 1 . The application scenario involves an automobile  1 . The automobile  1  includes a front windshield A and a head-up display device B. 
     A projection optical system  10  in the head-up display device B employs a double-telecentric projection lens  100  according to the embodiment of the present disclosure to achieve imaging and display of two image pictures. Light beams of a first image P 1  and a second image P 2  output by the double-telecentric projection lens  100  are capable of outputting the first image P 1  and the second image P 2  through a first lens  11  and a second lens  12  respectively in the projection optical system  10 . 
     In this application scenario, the first image P 1  is mainly configured to display a two-dimensional image, for example, driving information of the automobile  1 , wherein the driving information includes, but is not limited to, speed information, oil supply information, and the like of the automobile  1 . Accordingly, the automobile  1  should be equipped with a speed sensor, an oil supply sensor, and the like. Specifically, configurations of the two-dimensional image, the driving information of the automobile  1 , and the corresponding sensor may be selected according to the actual needs, which are not limited to those in the application scenario of the present disclosure. 
     In this application scenario, the second image P 2  is mainly configured to display a three-dimensional image, that is, an AR picture, for example, road condition information of a road where the automobile  1  is traveling, wherein the road condition information includes, but is not limited to, lanes, road lines, pedestrian crossings, obstacles, traffic lights, traffic sign boards, and the like. Accordingly, the automobile  1  should be equipped with a camera, a laser radar, and the like detection device. Further, where the automobile  1  is capable of implementing a navigation function, navigation indication information may also be over-displayed together with the road condition information. Specifically, configurations of the three-dimensional image, the road condition information of the road where the automobile  1  is traveling, and the corresponding detection device may be selected according to the actual needs, which are not limited to those in the application scenario of the present disclosure. 
     In this application scenario, the front windshield A is preferably made of a glass material that is capable of clearly achieving imaging and has a good light transmittance. Specifically, the material may be selected according to the actual needs, which is not limited to that in the application scenario of the present disclosure. 
     Hereinafter, the embodiments of the present disclosure are further illustrated with reference to the accompanying drawings. 
     First Embodiment 
     This embodiment of the present disclosure provides a double-telecentric projection lens, applicable to a projection optical system in a head-up display device mounted on an automobile. The head-up display device mounted on an automobile may be the head-up display device B of the automobile  1  as illustrated in the above application scenario. Referring to  FIG. 3  and  FIG. 4 , an optical path and structure of the double-telecentric projection lens according to an embodiment of the present disclosure are illustrated. The double-telecentric projection lens  100  includes a front lens group  120 , a rear lens group  130 , and an equivalent prism  140  that are successively arranged between an image side M and a DMD chip  110 . 
     The front lens group  120  includes a first lens  121 , a second lens  122 , a third lens  123 , a fourth lens  124 , and a fifth lens  125  that are successively arranged. The rear lens group  130  includes a sixth lens  136 , a seventh lens  137 , an eighth lens  138 , and a ninth lens  139  that are successively arranged. The third lens  123  and the fourth lens  124  constitute a double-cemented lens. The double-cemented lens has good capabilities in correcting spherical aberration, chromatic aberration, and secondary spectrum. The DMD chip  110  is configured to simultaneously emit two images, wherein during simultaneous emission of the two images from the DMD chip  110 , the simultaneously emitted two images are emitted from the double-telecentric projection lens  100  and imaged at different positions. 
     Specifically, the first lens  121 , the second lens  122 , the third lens  123 , the fourth lens  124 , the fifth lens  125 , the sixth lens  136 , the seventh lens  137 , the eight lens  138 , and the ninth lens  139  are all spherical lenses. An image side S 1  of the first lens  121  is a concave surface, and an object side S 2  of the first lens  121  is a convex surface; an image side S 3  of the second lens  122  is a convex surface, and an object side S 4  of the second lens  122  is a convex surface; an image side S 5  of the third lens  123  is a concave surface, and an object side S 6  of the third lens  123  is a concave surface; an image side S 6  of the fourth lens  124  is a convex surface, and an object side S 7  of the fourth lens  124  is a convex surface; an image side S 8  of the fifth lens  125  is a convex surface, and an object side S 9  of the fifth lens  125  is a convex surface; an image side S 10  of the sixth lens  136  is a concave surface, and an object side S 11  of the sixth lens  136  is a concave surface; an image side S 12  of the seventh lens  137  is a concave surface, and an object side S 13  of the seventh lens  137  is a convex surface; an image side S 14  of the eighth lens  138  is a convex surface, and an object side S 15  of the eight lens  138  is a convex surface; and an image side S 16  of the ninth lens  139  is a convex surface, and an object side S 17  of the ninth lens  139  is a concave surface. It should be noted that the object side S 6  of the third lens  123  and the image side of the fourth lens  124  are two totally attached surfaces, which are herein marked as a same surface. 
     The function of the equivalent prism  140  is to deflect the light, and separate an illumination optical path from an imaging optical path to prevent interference. In some embodiments, the equivalent prism is a turning prism and a right-angle triangular prism, wherein one right-angle surface of the right-angle triangular prism is opposite to a light exit surface of the DMD chip  110 , the other right-angle surface of the right-angle triangular prism is opposite to a light incident side of the rear lens group  130 , and an inclined surface of the right-angle triangular prism has a reflection angle of 90 degrees; and 
     The DMD chip  110  includes an effective surface  111  of the DMD chip  110 , and a protective glass  112  of the DMD chip  110 . The DMD chip  110  is configured to emit the light beams for imaging. In an embodiment of the present disclosure, the DMD chip  110 , as illustrated in  FIG. 3 , is divided into an upper region and a lower region, wherein the two regions are respectively configured to emit two light beams for imaging. 
     Specifically, as illustrated in Table 1, a group of actual design parameters of the double-telecentric projection lens  100  according to an embodiment of the present disclosure are illustrated. In the design parameters, a total optical length of the double-telecentric projection lens  100  according to an embodiment of the present disclosure may be controlled to be 150 mm, the double-telecentric projection lens  100  has an effective focal length of 90 mm, has a magnification of 1:1, and has a relative aperture of 2. 
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Minor serial  
                 Radius of curvature 
                 Thickness  
                 Glass  
               
               
                   
                 number 
                 (mm) 
                 (mm) 
                 material 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 S1 
                 −430 
                 7 
                 H-ZLAF78B 
               
               
                   
                 S2 
                 −70 
                 3 
                   
               
               
                   
                 S3 
                 43.2 
                 8 
                 H-ZPK5 
               
               
                   
                 S4 
                 −51 
                 9 
                   
               
               
                   
                 S5 
                 −20 
                 5 
                 F13 
               
               
                   
                 S6 
                 26.0 
                 9 
                 H-LAK4L 
               
               
                   
                 S7 
                 −22 
                 3 
                   
               
               
                   
                 S8 
                 16.2 
                 6 
                 N-FK51A 
               
               
                   
                 S9 
                 −82 
                 5 
                   
               
               
                   
                  S10 
                 −30 
                 4 
                 H-ZBAF4 
               
               
                   
                  S11 
                 15 
                 6 
                   
               
               
                   
                  S12 
                 −9.0 
                 4 
                 H-ZF52 
               
               
                   
                  S13 
                 −12.0 
                 2 
                   
               
               
                   
                  S14 
                 285.5 
                 8 
                 H-LAK4L 
               
               
                   
                  S15 
                 −35 
                 1 
                   
               
               
                   
                  S16 
                 23 
                 6 
                 H-ZLAF78B 
               
               
                   
                  S17 
                 28.3 
                 0 
               
               
                   
                   
               
            
           
         
       
     
     Based on the double-telecentric projection lens as illustrated in  FIG. 3  and  FIG. 4  and the actual design parameters of the double-telecentric projection lens as listed in Table 1, an imaging quality diagram of double-telecentric projection lens  100  in the full field and full wave-band as illustrated in  FIG. 6  to  FIG. 9  may be acquired. Specifically, 
       FIG. 6  is a schematic diagram of full field transfer function (MTF) values of the double-telecentric projection lens  100  according to an embodiment of the present disclosure. As illustrated in  FIG. 6 , the full field MTF of the double-telecentric projection lens  100  is controlled to be greater than 40%. 
       FIG. 7  is a schematic diagram of distortion and field curvature of a full field and full wave-band of the double-telecentric projection lens  100  according to an embodiment of the present disclosure, wherein the left part illustrates the field curvature, and the right part illustrates the distortion. As illustrated in  FIG. 7 , with respect to the double-telecentric projection lens  100 , the field curvature is controlled to be less than 0.2 mm, and the distortion is controlled to be less than 0.5%. 
       FIG. 8  is a schematic diagram of vertical chromatic aberration of a full field and full wave-band of the double-telecentric projection lens  100  according to an embodiment of the present disclosure. As illustrated in  FIG. 8 , the vertical chromatic aberration of the double-telecentric projection lens  100  is not greater than 1 μm. 
       FIG. 9  is a schematic diagram of dot columns of a full field of the double-telecentric projection lens  100  according to an embodiment of the present disclosure. As illustrated in  FIG. 8 , a root mean square (RMS) radius of the double-telecentric projection lens  100  is controlled in the range of 5.0 μm&lt;RMS&lt;8 μm. 
     Second Embodiment 
     This embodiment of the present disclosure provides a head-up display device mounted on an automobile. The head-up display device mounted on an automobile may be the head-up display device B of the automobile  1  as illustrated in the above application scenario. Referring to  FIG. 10  and  FIG. 11 ,  FIG. 10  illustrates a structure of a head-up display device mounted on an automobile according to an embodiment of the present disclosure, and  FIG. 11  illustrates a structure of an optical path of a projection optical system in the head-up display device B of the automobile  1  in  FIG. 10 . The head-up display device B of the automobile  1  includes a projection optical system  10  capable of projecting a first image P 1  and a second image P 2  on a front windshield A of the automobile  1  such that imaging is achieved on the front windshield. The projection optical system  10  includes the double-telecentric projection lens  100  as described in the first embodiment, and a first lens  11 , a second lens  12 , a light splitting device  13 , a first reflection unit  14 , and a second reflection unit  15 . 
     The double-telecentric projection lens  100  is the double-telecentric projection lens  100  as described in first embodiment. The structure, connection relationship, arrangement position, optical path, and the like of the double-telecentric projection lens  100  may refer to the specific description of the first embodiment, which is not described herein. 
     An optical center of the light splitting device  13  is arranged on an image side of the double-telecentric projection lens  100 , and a light incident side of the light splitting device  13  is arranged to face a light exit side of the double-telecentric projection lens  100 . Further, the light splitting device  13  includes a first reflection structure  13   a  and a second reflection structure  13   b;  wherein the first reflection structure  13   a  is configured to receive and reflect the light beam of the first image, the second reflection structure  13   b  is configured to receive and reflect the light beam of the second image, a light reflection side of the first reflection structure  13   a  is a first light reflection side of the light splitting device  13 , and a light reflection side of the second reflection structure  13   b  is a second light reflection side of the light splitting device  13 . Optionally, the first reflection structure  13   a  and the second reflection structure  13   b  are both a mirror; or the first reflection structure  13   a  and the second reflection structure  13   b  are both a combination of a mirror, and a filter, a highly reflective film and/or an anti-reflection lens. 
     A light incident side of the first reflection unit  14  is arranged to face a first light reflection side of the light splitting device  13 . The first reflection unit  14  is a mirror arranged at a predetermined angle between the light splitting device  13  and the first lens  11 . The first reflection unit  14  may also include a highly reflective film coated on the mirror to achieve total reflection of the light beams. In the embodiment as illustrated in  FIG. 11  of the present disclosure, an inclined surface of the first reflection unit  14  has a reflection angle of 90 degrees. In some other configurations, the first reflection unit  14 , and the angle thereof may be configured according to the actual needs, which are not limited to those in the embodiment of the present disclosure. 
     A light incident side of the first lens  11  is arranged to face a light reflection side of the first reflection unit  14 , and a light exit side of the first lens  11  is configured to emit the first image. Specifically, the first lens  11  may be a single lens or a lens group composed of a plurality of lenses, and may also contain other optical instruments. In practical application scenarios, the first lens  11  may be configured according to the actual needs, which is not limited to that in the embodiment of the present disclosure. 
     A light incident side of the second reflection unit  15  is arranged to face a second light reflection side of the light splitting device  13 . The second reflection unit  15  is a mirror arranged at a predetermined angle between the light splitting device  13  and the first lens  12 . The second reflection unit  15  may also include a highly reflective film coated on the mirror to achieve total reflection of the light beams. In the embodiment as illustrated in  FIG. 11  of the present disclosure, an inclined surface of the second reflection unit  15  has a reflection angle of 90 degrees. In some other configurations, the second reflection unit  15 , and the angle thereof may be configured according to the actual needs, which are not limited to those in the embodiment of the present disclosure. 
     A light incident side of the second lens  12  is arranged to face a light reflection side of the second reflection unit  15 , and a light exit side of the second lens  12  is configured to emit the second image. Specifically, the second lens  12  may be a single lens or a lens group composed of a plurality of lenses, and may also contain other optical instruments. In practical application scenarios, the second lens  12  may be configured according to the actual needs, which is not limited to that in the embodiment of the present disclosure. 
     The embodiments of the present disclosure provide a double-telecentric projection lens. The double-telecentric projection lens includes a front lens group, a rear lens group, and an equivalent prism that are successively arranged between an image side and a DMD chip; wherein the front lens group includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens that are successively arranged, and the rear lens group includes a sixth lens, a seventh lens, an eighth lens, and a ninth lens that are successively arranged, wherein the third lens and the fourth lens constitute a double-cemented lens; and the DMD chip is configured to simultaneously emit two images, wherein during simultaneous emission of the two images from the DMD chip, the simultaneously emitted two images are emitted from the double-telecentric projection lens and imaged at different positions. The double-telecentric projection lens according to the embodiments of the present disclosure is applicable to the projection optical system in the head-up display device mounted on an automobile such that simultaneous projection imaging of two pictures is achieved, and the imaging effect is good. 
     It should be noted that the above described device embodiments are merely for illustration purpose only. The units which are described as separate components may be physically separated or may be not physically separated, and the components which are illustrated as units may be or may not be physical units, that is, the components may be located in the same position or may be distributed into a plurality of network units. Part or all of the modules may be selected according to the actual needs to achieve the objects of the technical solutions of the embodiments. 
     Finally, it should be noted that the above embodiments are merely used to illustrate the technical solutions of the present disclosure rather than limiting the technical solutions of the present disclosure. Under the concept of the present disclosure, the technical features of the above embodiments or other different embodiments may be combined, the steps therein may be performed in any sequence, and various variations may be derived in different aspects of the present disclosure, which are not detailed herein for brevity of description. Although the present disclosure is described in detail with reference to the above embodiments, persons of ordinary skill in the art should understand that they may still make modifications to the technical solutions described in the above embodiments, or make equivalent replacements to some of the technical features; however, such modifications or replacements do not cause the essence of the corresponding technical solutions to depart from the spirit and scope of the technical solutions of the embodiments of the present disclosure.