Patent Publication Number: US-2023161091-A1

Title: Stage light fixture with split light mixing device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of International Application No. PCT/CN2022/102654, filed on Jun. 30, 2022, which claims priorities from Chinese Invention Application No. 202122871943.X filed on Nov. 23, 2021, 202221023098.9 filed on Apr. 29, 2022, and 202221330142.0 filed on May 31, 2022, all of which are hereby incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to the technical field of stage light fixtures, and more particularly, relates to a stage light fixture with a split light mixing device. 
     BACKGROUND 
     In the most of light fixtures, light spots with a color effect are projected in combination with LED chips and a light guide. Generally, the light guide is provided with a frosting sheet on the side thereof away from the light source to produce more uniform light spots. As shown in  FIG.  1   , in order to prevent light leakage between the frosting sheet and the light guide, an integrated configuration of them is provided in most cases. Although such configuration can firmly combine the frosting sheet and the light guide, the integrated configuration requires high processing accuracy, resulting in increased processing difficulty, and cost is difficult to lower. 
     Moreover, according to the existing light guide, the light guide with such integrated configuration is usually placed in the through hole of a holder. The light guide is prevented from falling during operation with the frosting sheet, which is located on the light output surface of the light guide, abutted against the step portion on the holder, and fastened with the holder with a cover buckled. However, such fastening method requires high stability for connection between the cover and the holder, as once the cover and the holder are accidentally loosened, the light guide will slide out of the holder to cause damage to the light guide and even damage to other components inside the light fixture. 
     SUMMARY 
     Accordingly, the present invention provides a stage light fixture with a split light mixing device, which is free from the problems difficult to process a light guide. 
     According to the present invention, a stage light fixture with a split light mixing device is provided, which includes a light source for generating a light beam and a light mixing device for reflecting the light beam at least one time. The light mixing device includes a light guide with a gradually changing cross-sectional area and a light beam homogenizer for receiving the light beam emitted from a light output surface of the light guide. The light beam homogenizer and the light guide are arranged independent of each other in the present invention, and the cross-sectional area of the light beam homogenizer is at least 1.1 times of the cross-sectional area of the light output surface. The stage light fixture further includes a holder for clamping and fixing the light guide and a cover fastened to the end of the holder away from the light source. The cover is configured to press the light beam homogenizer tightly to make the light beam homogenizer closely attached to the light output surface. 
     In the present invention, the light beam homogenizer is tightly attached to the light output surface of the light guide by pressure applied to the light beam homogenizer via the cover, so that too large gap between the light beam homogenizer and the light output surface can be prevented, light leakage thus can be avoided, thereby reducing light loss. In addition, the ratio of the cross-sectional area of the light beam homogenizer to the cross-sectional area of the light output surface is defined, the light beam homogenizer thus can completely cover the light output surface, as a result, precise pre-positioning of the light beam homogenizer is not required when mounting the light beam homogenizer. Therefore, fixing and mounting of the light beam homogenizer will be more convenient. According to the present invention, the light beam homogenizer and the light guide are independent of each other, which thus can be processed separately. In such easy way, processing thereof is simplified, and no high processing accuracy is required, thus reducing processing difficulty. The present invention can also achieve different frosting effects, only by using light beam homogenizers of different frosting degrees according to requirements. Therefore, the light fixture according to the present invention can achieve a variety of light effects, which is more universality, thereby further reducing costs. 
     According to at least one embodiment of the present invention, the end surface of the holder away from the light source is formed an accommodating cavity for accommodating the light beam homogenizer. The accommodating cavity is recessed in a direction close to the light source. The thickness of the light beam homogenizer is greater than or equal to the depth of the accommodating cavity. With such configuration, when mounting the light beam homogenizer, the light guide is firstly inserted into the holder, the light beam homogenizer is placed in the accommodating cavity, pressure then is applied to the light beam homogenizer via the cover, the light beam homogenizer thus moves close to the light guide and is fixed to the light output surface of the light guide. During the process of applying pressure via the cover, the light beam homogenizer is in surface contact with the light output surface, the force between the light beam homogenizer and the light output surface thus is even, which will be not likely to cause damage while achieving tight pressing. The thickness of the light beam homogenizer is designed to be greater than or equal to the depth of the accommodating cavity, so that the cover can be kept pressing the light beam homogenizer tightly, thereby ensuring the light beam homogenizer being closely attached to the light output surface of the light homogenizing rod all the time. 
     In order to prevent movement of the beam homogenizer during operation of the light fixture, the side wall of the accommodating cavity can be provided with several positioning ribs for abutting against the periphery of the light beam homogenizer. In such configuration, the light beam homogenizer can be stably placed in the accommodating cavity to limit movement thereof during operation. 
     In order to make the light beam homogenizer more closely attached to the light output surface, the side surface of the light beam homogenizer close to the light output surface can be a smooth surface. 
     While the side surface of the light beam homogenizer away from the light output surface can be formed as a frosting surface. The frosting surface can homogenize the light projected from the light output surface so that the light spot formed can be more uniform in color without obvious color blocks when in color mixing. 
     According to at least one embodiment of the present invention, the cover has a light passing hole for the light beam to pass through, and in the light emitting direction, the projection of the light output surface is located in the light passing hole. As the light beam is reflected in the light guide at least one time, the light beam will be emitted from the light output surface at a certain angle, rather than perpendicularly. In such configuration, it can ensure that the light beam emitted from the light output surface can pass through the light passing hole as much as possible, thus avoiding light loss caused by shielding of the cover. 
     The cross-sectional area of the light beam homogenizer can be more than twice of the cross-sectional area of the light output surface. By defining such a ratio, the contact area between the light beam homogenizer and the cover can be increased, resulting in that the cover can press the light beam homogenizer tightly all the time and the light beam homogenizer can suffer force more evenly. 
     To achieve fixed connection between the holder and the cover, in the length direction of the holder, the cover is formed at least two connecting plates extending to the holder, the holder is provided with fastening portions corresponding to the connecting plates, and the cover is fastened to the holder via the connecting plates cooperated with the fastening portions. With the cover fastened to the holder, the light guide can be prevented from sliding out of the light passing hole during operation, forming dual protection to the light guide, thus further enhancing fixing effect on the light guide. 
     According to the present invention, the material of the cover can be metal, and the cover is provided with an elastic member for abutting against the light guide. The cover made of the metal has better high-temperature resistance and better heat transfer performance, the local heat can be conducted to the whole structure for dissipation. Therefore, the high-temperature burn due to strong light thereof can be avoided to protect the holder. The cover is abutted against the light guide by the elastic member, which can prevent inelastic collision between the light guide and the cover, thus making the light guide more securely fixed. 
     Specifically, the elastic member can be in form of a metal elastic piece connected to the cover. The configuration of the metal elastic piece will take up less space, which can be directly cut and formed integrally with the cover made of the metal material, forming a simpler structure. 
     According to the present invention, the metal elastic piece has a connecting segment and an abutting-pressing segment connected to each other. The connecting segment is connected to the inner side of the light passing hole, and the abutting-pressing segment is abutted against the light guide. In such configuration, when the abutting-pressing segment is connected to the cover via the connecting segment and the metal elastic piece is subjected to an external force, the abutting-pressing segment will be bent in the normal direction of the cover with the connecting segment as a base point, thereby generating an elastic force to elastically abut against the light guide. 
     The number of the metal elastic piece can be multiple according to the present invention, the abutting-pressing segment of each metal elastic piece is in an arc shape, and the abutting-pressing segment of the plurality of metal elastic pieces are successively end-to-end to form a ring shape. 
     According to the present invention, the elastic member can also be an elastic spacer or a spring, which is disposed between the cover and the light guide. When the sizes of the cover or the light guide are changed, the elastic spacer or spring can still be applied, which has more universality. 
     In order to avoid the situation that when the cover applies pressure to the light beam homogenizer, the light beam homogenizer will be damaged by the cover due to too small thickness of the light beam homogenizer, the thickness of the light beam homogenizer is designed to range from 1 mm to 3 mm according to the present invention. 
     According to at least one embodiment of the present invention, the holder further includes a through hole for mounting the light guide, the end surface of the holder far away from the light source is, in the direction close to the light source, provided with tensioning grooves running through the side wall of the through hole, and the end of the light guide close to the light beam homogenizer is in an interference fit with the holder. With the configuration of the tensioning groove, one end surface of the holder has elasticity, so that when the light guide is inserted in the direction close to the light source, the tensioning groove will provide a certain tensioning force to enable the light guide to form interference fit with the holder. Therefore, the light guide can be clamped and fixed only by means of the holder. High stability thus can be achieved in such fixing way, the light guide will not be prone to fall off during operation, and the tensioning groove has the advantages that simple in structure and easy to process. 
     In order to achieve closer fit between the light guide and the holder, several first ribs for fixing the light guide are further provided in the through hole, which extend in the length direction of the holder, and the through hole is in an interference fit with the light guide via the first ribs. The light guide is pressed tightly via the first ribs according to the present invention, the contact area between the holder and the light guide is reduced, thereby increasing the intensity of pressure of the holder to the light guide, and enabling closer fit between the light guide and the holder. 
     The end of the light guide close to the light source is a first light guide segment, the side wall of the first light guide segment has a plurality of edges, and in the length direction of the through hole, the inner side wall of the through hole is provided with positioning grooves corresponding to the edges of the first light guide segment. With such configuration, the edges of the first light guide segment, when inserted, can be matched with the respect positioning groove, thereby enabling the light guide to be quickly and accurately inserted and fixed in the through hole. 
     In order to prevent the light guide from moving during operation, second ribs are provided on both sides of the positioning groove, and each second rib extends in the length direction of the through hole. In such configuration, the positioning groove clamp the edges of the light fixture cooperating with the second ribs to prevent the light guide from moving during operation. 
     According to the present invention, the cover can further include light shielding plates for shielding the tensioning groove when the cover is fastened to the holder. The light shielding plate can prevent light leakage when the light is emitted from the tensioning groove. 
     Preferably, in a direction away from the light source, the cross-sectional area of the light guide is gradually increased, and correspondingly, the cross-sectional area of the through hole is gradually increased. In a direction close to the light source, the end of the light guide close to the light incoming surface is inserted into the through hole, then the light guide is gradually pushed, and finally forming interference fit therebetween. In such way, the holder thus can clamp and fix the light guide more stably. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is an exploded view of a light guide and a mounting base according to a prior art; 
         FIG.  2    is an exploded view including a light mixing device, a holder and a cover according to an embodiment of the present invention; 
         FIG.  3    is a schematic view of the holder shown in  FIG.  2   ; 
         FIG.  4    is a sectional view, with the light mixing device, the holder and the cover assembled, according to an embodiment of the present invention; 
         FIG.  5    is a top view of a light mixing device according to an embodiment of the present invention, viewed from a light output surface of the light guide; 
         FIG.  6    is a bottom view of a light mixing device according to an embodiment of the present invention, viewed from a light incoming surface of the light guide; 
         FIG.  7    is a schematic view of a cover according to an embodiment of the present invention; and 
         FIG.  8    is a schematic view showing a plurality of light mixing devices mounted on a substrate according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The accompanying drawings of the present invention are for exemplary illustration only, and should not be construed as limitations on the present invention. In order to better illustrate the following embodiment, some parts in the accompanying drawings may be omitted, enlarged or reduced, and they do not represent the size of the actual product; for those skilled in the art, it is understandable that certain well-known structures and descriptions thereof in the drawings may be omitted. 
     Referring to  FIG.  2    to  FIG.  5   , a stage light fixture with a split light mixing device is provided according to one embodiment, which includes a light source  200  for generating a light beam, and a light mixing device for reflecting the light beam many times. The light mixing device specifically includes a light guide  110  with a gradually changing cross-sectional area and a light beam homogenizer  120  for receiving the light beam emitted from a light output surface  111  of the light guide  110 . The light beam homogenizer  120  and the light guide  110  are arranged independent of each other, and the cross-sectional area of the light beam homogenizer  120  is at least 1.1 times of the cross-sectional area of the light output surface  111 . The stage light fixture further includes a holder  130  for clamping and fixing the light guide  110 , and a cover  140  which is fastened to an end of the holder  130  away from the light source  200 , the cover  140  is configured to press the light beam homogenizer  120  tightly to make the light beam homogenizer  120  closely attached to the light output surface  111 . 
     According to the present embodiment, the light beam homogenizer  120  is tightly attached to the light output surface  111  by pressure applied to the light beam homogenizer  120  via the cover  140 . With such configuration, too large gap between the light beam homogenizer  120  and the light output surface  111  can be prevented, light leakage thus can be avoided, thereby reducing light loss. is In addition, the ratio of the cross-sectional area of the light beam homogenizer  120  to the cross-sectional area of the light output surface  111  is defined so that the light beam homogenizer  120  can completely cover the light output surface  111 , as a result, precise pre-positioning of the light beam homogenizer  120  is not required when mounting the light beam homogenizer  120 . Therefore, it is more convenient to fix and mount the light beam homogenizer  120 . Further, the light beam homogenizer  120  and the light guide  110  are independent of each other, which thus can be processed separately. In such easy way, processing thereof is simplified, and no high processing accuracy is required, the processing difficulty thus is reduced. The light beam homogenizer  120  can also be replaced with light beam homogenizers of different frosting degrees according to requirements to achieve different frosting effects. Therefore, the light fixture can achieve a variety of light effects, which is more universality, thereby further reducing costs. 
     In the present embodiment, the cross-sectional area of the light guide  110  is gradually increased along the direction away from the light source  200 , and a light incoming surface  112  of the light guide  110  is smoothly transited to the light output surface  111  of the light guide  110 . 
     Preferably, as shown, the light guide  110  is smoothly transited from the light incoming surface  112  in form of regular quadrilateral to the light output surface  111  in form of regular octagonal. In such configuration, the light beam generated by the light source  200  will be reflected by the light guide  110  many times, and the light spot thus formed will be nearly circular, thereby achieving well light mixing and color mixing. All side surfaces of the light guide  110  may be in flat and smooth planes. 
     According to some embodiments, the stage light fixture includes a plurality of light sources  200  which are mounted on a substrate  300 , thus at least two light mixing devices are provided. Referring to  FIG.  8   , the stage light fixture further includes a pressing plate  400  which having a plurality of mounting holes for each holder  130  to penetrate. Each holder  130  has four support ribs  136  extending along a direction of light emitting and four supporting legs  135  extending along a direction close to the light source  200 . As  FIG.  8    shown, each holder  130  is abutted against the substrate  300  via the supporting legs  135 , the supporting ribs  136  are pressed tightly by the pressing plate  400 , and the pressing plate  400  and the substrate  300  are connected by a connecting column. With the pressing plate  400  cooperated with the substrate  300 , each holder  130  thus is fixed above the respect light source  200  without displacement. In addition, with the configuration of the four supporting legs  135  distributed around the light source  200 , and the light incoming surface  110  of each light guide  110  is located over the respect light source  200 , the light beam emitted from the light source  200  will enter the light guide  110  as much as possible. 
     Referring back to  FIG.  2    to  FIG.  5   , an end surface of the holder  130  away from the light source  200  is formed an accommodating cavity  131  for accommodating the light beam homogenizer  120  which is recessed in a direction close to the light source  200 . The thickness of the light beam homogenizer  120  can be greater than or equal to the depth of the accommodating cavity  131 . When mounting the light beam homogenizer  120 , the light guide  110  is firstly inserted into the holder  130 , then the light beam homogenizer  120  is placed in the accommodating cavity  131 . Pressure then can be applied to the light beam homogenizer  120  via the cover  140  so that the light beam homogenizer moves close to the light guide  110  and is fixed to the light output surface  111  of the light guide  110 . During the process of applying pressure via the cover  140 , the light beam homogenizer  120  is in surface contact with the light output surface  111 , the force between the light beam homogenizer and the light output surface thus is even, which will be not likely to cause damage while achieving tight pressing. The thickness of the light beam homogenizer  120  is greater than or equal to the depth of the accommodating cavity  131 , in such configuration, the cover  140  can be kept pressing the light beam homogenizer  120  tightly, thereby always ensuring the light beam homogenizer  120  being closely attached to the light output surface  111  of the light homogenizing rod. 
     The thickness of the light beam homogenizer  120  is preferably greater than the depth of the accommodating cavity  131 . 
     The side wall of the accommodating cavity  131  can be provided with several positioning ribs  1311  for abutting against the periphery of the light beam homogenizer  120 . With such configuration, the light beam homogenizer  120  thus can be stably placed in the accommodating cavity  131  to prevent movement thereof during operation. 
     In the present embodiment, the positioning ribs  1311  are uniformly distributed on the side wall of the accommodating cavity  131 , one end of each positioning rib  1311  is connected to the bottom of the accommodating cavity  131 , and the other end of each positioning rib is extended to the opening surface of the accommodating cavity  131 , so that the light beam homogenizer  120  will suffer stress more evenly. When mounting the light beam homogenizer  120 , positioning can be achieved only by placing the light beam homogenizer  120  in the accommodating cavity  131 , achieving more convenient operation. 
     The cross section of the light beam homogenizer  120  and the cross section of the accommodating cavity  131  are preferably both circular. While the shape of the accommodating cavity  131  can be in any form which matches the shape of the light beam homogenizer  120 . 
     In a preferable embodiment of the present invention, the side surface of the light beam homogenizer  120  close to the light output surface  111  is a smooth surface  121 . With such smooth surface  121 , the light beam homogenizer  120  can be more closely attached to the light output surface  111 . 
     While the side surface of the light beam homogenizer  120  away from the light output surface  111  is a frosting surface  122 . The frosting surface  122  can homogenize the light projected from the light output surface  111  so that the light spot formed is more uniform in color without obvious color blocks. 
     According to an embodiment, the cover  140  has a light passing hole  141  for the light beam to pass through, and in the light emitting direction, the projection of the light output surface  111  is located in the light passing hole  141 . As the light beam is reflected in the light guide  110  many times, the light beam will be emitted from the light output surface  111  at a certain angle, rather than perpendicularly. In such way, it ensures that the light beam emitted from the light output surface  111  can pass through the light passing hole  141  as much as possible, avoiding light loss caused by shielding of the cover  140 . 
     The surface of the cover  140  is preferably treated with anti-reflection process to prevent the light beam from being reflected on the surface of the cover  140  to form stray light. 
     According to a preferable embodiment, the cross-sectional area of the light beam homogenizer  120  is more than twice of the cross-sectional area of the light output surface  111 . With such configuration, contact area between the light beam homogenizer  120  and the cover  140  can be increased, resulting in that the cover  140  can press the light beam homogenizer  120  tightly all the time and the light beam homogenizer  120  can suffer force more evenly. 
     More preferably, the cross-sectional area of the light beam homogenizer  120  is 2.5 times of the cross-sectional area of the light output surface  111 . 
     According to some embodiments, the cover  140  is formed at least two connecting plates extending to the holder in the length direction of the holder. The holder is provided with a fastening portion corresponding to each connecting plate. The cover  140  thus is fastened to the holder via the connecting plates. With the cover  140  fastened to the holder, the light guide can be prevented from sliding out of the light passing hole  141  during operation, forming dual protection to the light guide, thus further enhancing the fixing effect on the light guide. 
     According to a preferable embodiment, as shown in  FIG.  2   , the fastening portion is a first protrusion  134  on the outer side wall of the holder  130 , the fixing portion is a fastening hole  143  formed in the connecting plate corresponding to the first protrusion, the cover  130  thus can be fastened to the end surface of the holder away from the light source  200  by cooperation with the first protrusion and the fastening hole. 
     Preferably, the surface of the cover is a matte surface, which can avoid glare when the light is reflected by the surface of the cover after emitted from the light passing hole. The matte surface can be formed by spraying matte paint or by grinding. 
     As shown in  FIG.  7   , the material of the cover can be metal, and the cover is provided with an elastic member for abutting against the light guide. As the cover made of metal material has better high-temperature resistance and better heat transfer performance, local heat can be conducted to the whole structure for dissipation. Therefore, high-temperature burn due to strong light thereof can be avoided to protect the holder. The cover  140  is abutted against the light guide via the elastic member, which can prevent inelastic collision between the light guide and the cover, thus making the light guide more securely fixed. 
     The elastic member  144  can be in form of a metal elastic piece  145  connected to the cover  140 . The metal elastic piece  145  connected to the cover  140  will take up less space, and the metal elastic piece  145  can be directly cut and formed integrally with the cover  140  made of metal material, which is simple in structure. 
     As shown in  FIG.  7   , the metal elastic piece  145  includes a connecting segment  146  and an abutting-pressing segment  147  connected to each other. The connecting segment  146  is connected to the inner side of the light passing hole  141 , and the abutting-pressing segment is abutted against the light guide  110 . When the abutting-pressing segment  147  is connected to the cover  140  via the connecting segment  146  and the metal elastic piece  145  is subjected to an external force, the abutting-pressing segment  147  will be bent in the normal direction of the cover with the connecting segment  146  as a base point, thereby generating an elastic force to elastically abut against the light guide  110 . 
     The number of the metal elastic piece  145  can be multiple as  FIG.  7    shown. In such configuration, each abutting-pressing segment  147  is in an arc shape, and the abutting-pressing sections  147  of the plurality of metal elastic pieces  145  are end-to-end successively to be in a ring shape. 
     Preferably, the number of the metal elastic pieces is 3. 
     According to a preferable embodiment of the present invention, the thickness of the light beam homogenizer  120  ranges from 1 mm to 3 mm, which can avoid the situation that when the cover  140  applies pressure to the light beam homogenizer  120 , the light beam homogenizer is damaged by the cover  140  due to too small thickness of the light beam homogenizer  120 . 
     More preferably, the thickness of the light beam homogenizer  120  is 2 mm and the depth of the accommodating cavity  131  is 1.5 mm, so that when the cover  140  is fastened to the side wall of the holder  130 , the cover  140  maintains in a state of applying pressure to the light beam homogenizer  120 . Therefore, the light beam homogenizer  120  can be closely attached to the light output surface  111  of the light guide  110  all the time. 
     Referring back to  FIG.  2    to  FIG.  5   , especially  FIG.  2    the holder  130  further includes a through hole  132  for mounting the light guide  110 , the end surface of the holder  130  far away from the light source  200  is, in the direction close to the light source  200 , provided with tensioning grooves  133  running through the side wall of the through hole  132 , and the end of the light guide  110  close to the light beam homogenizer  120  is in an interference fit with the holder  130 . With the configuration of the tensioning groove  133 , one end surface of the holder  130  has elasticity, so that when the light guide  110  is inserted in the direction close to the light source  200 , the tensioning groove  133  will provide a certain tensioning force to enable the light guide  110  to form interference fit with the holder  130 . Therefore, the light guide  110  can be clamped and fixed only by means of the holder  130 . High stability thus can be achieved in such easy fixing way, the light guide  110  will not be prone to fall off during operation, and the tensioning groove  133  has the advantages that simple in structure and easy to process. 
     Preferably, the number of the tensioning grooves  133  is two, and the two tensioning grooves coincide with the diameter of the through hole. 
     According to the present embodiment, several first ribs  510  for fixing the light guide  110  are further provided in the through hole  132 , as  FIG.  2    and  FIG.  3    shown, which extend in the length direction of the holder  130 . The through hole  132  thus is in an interference fit with the light guide  110  via the first ribs  510 . The light guide  110  is pressed tightly via the first ribs  510 , the contact area between the holder  130  and the light guide  110  is reduced, thereby increasing the intensity of pressure of the holder  130  to the light guide  110 , and enabling closer fit between the light guide  110  and the holder  130 . 
     Preferably, the first rib extends from one end to the other end of the through hole, which facilitates processing. 
     Referring to  FIG.  6   , the end of the light guide close to the light source is a first light guide segment, the side wall of the first light guide segment has a plurality of edges  113 , and in the length direction of the through hole  132 , the inner side wall of the through hole  132  is provided with positioning grooves  137  corresponding to the edges of the first light guide segment. With such configuration, the edges  113  of the first light guide segment, when inserted, can be matched with the respect positioning groove  137 , thereby enabling the light guide  130  to be quickly and accurately inserted and fixed in the through hole  132 . 
     Preferable, the positioning grooves  137  runs through the both ends of the through hole  132 , making processing easy and more facilitating positioning. 
     While the positioning grooves  137  may not run through the both ends of the through hole  132 , namely the positioning grooves  137  may only be provided for one segment, according to some embodiments. The length of each positioning groove  137  is consistent with the length of the first light guiding segment, and the positioning groove  137  starts to extend from the end of the through hole  132  close to the light source  200 . 
     A second light guide segment connected to the first light guide segment is further included, the end surface of the first light guide segment close to the light source is the light incoming surface, and the end surface of the second light guide segment away from the light source is the light output surface. 
     As shown in  FIG.  6   , second ribs  520  can be provided on both sides of the positioning groove  137  according to some embodiments, and each second rib  520  extends in the length direction of the through hole  132 . In such embodiment, the positioning grooves  137  clamp the edges  113  of the light guide  110  cooperating with the second ribs  150 , which can prevent the light guide from moving during operation. 
     The cover  140  can further include light shielding plates  142  for shielding the tensioning groove  137  when the cover  140  is fastened to the holder  130 . The light shielding plate  142  can prevent light leakage as the light is emitted from the tensioning groove  133 . 
     According to a preferable embodiment, in the direction away from the light source  200 , the cross-sectional area of the light guide  110  is gradually increased, and the cross-sectional area of the through hole  132  is correspondingly gradually increased. In a direction close to the light source  200 , the end of the light guide  110  close to the light incoming surface  112  is inserted into the through hole  132 , then the light guide  110  is gradually pushed, and finally forming interference fit therebetween. In such way, the holder  130  thus can clamp and fix the light guide  110  more stably. 
     Obviously, the above-mentioned embodiments of the present invention are only examples for clearly illustrating the technical solutions of the present invention, rather than limiting the specific implementation modes of the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the claims of the present invention shall be included within the protection scope of the claims of the present invention.