Patent Publication Number: US-9890920-B2

Title: Vehicular lamp

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority from Japanese Patent Application No. 2014-191862, filed on Sep. 19, 2014, with the Japan Patent Office, the disclosure of which is incorporated herein in its entirety by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a vehicular lamp used in, for example, an automobile. 
     BACKGROUND 
     As a light source of a vehicular lamp, a semiconductor light source such as, for example, a light emitting diode (LED) or a semiconductor laser, is being used, in lieu of a conventional bulb such as, for example, an incandescent bulb. Such a semiconductor light source has various advantages, such as for example, a variety of designs through a combination with light guides or high power saving, as compared to a bulb. See, for example, Japanese Patent Laid-Open Publication No. 2003-141909 and Japanese Patent Laid-Open Publication No. 2005-347144. 
     SUMMARY 
     A vehicular lamp using a conventional semiconductor light source has been developed, focusing on uniform light emission with a reduced point light feeling. In other words, a light emission pattern is monotonous and there remains room for improvement in terms of a high quality feeling. 
     The present disclosure has been made in view of the foregoing circumstances, and one of illustrative objects of an exemplary embodiment thereof is to provide a vehicular lamp capable of creating a jewel-like brilliancy when the vehicular lamp is turned on and/or off. 
     An aspect of the present disclosure relates to a vehicular lamp. The vehicular lamp includes: a plurality of light sources arranged in a row; a light guide configured to receive light emitted from the plurality of light sources on a rear surface thereof, and emit the light from a front surface thereof. The light guide includes: a base having a rear surface facing the plurality of light sources and extending in an arrangement direction of the plurality of light sources; a plurality of rear surface projections protruding from the rear surface of the base; and a plurality of front surface projections protruding from a front surface of the base. The plurality of rear surface projections and the plurality of front surface projections are arranged in the arrangement direction to be spaced apart from one another, and are formed in a plurality of projection forming areas, respectively. Each of the projection forming areas has a cross section, in which a side in a width direction of the base, which is perpendicular to the arrangement direction, becomes a longer side. Each of the plurality of front surface projections has a polyhedral shape including a plurality of faces that are successive in a circumferential direction thereof. 
     According to this aspect, when the vehicular lamp is turned on, the light emitted from a light source and incident on a rear surface projection is introduced into a front surface projection and multiple-reflected by the plurality of faces of the polyhedral front surface projection, so that a jewel-like brilliancy may be created. In addition, when the vehicular lamp is turned off, external light such as, for example, sunlight, is incident on the plurality of faces of the polyhedral front surface projection, such that a jewel-like glittering effect may be created. 
     Each of the plurality of faces of the front surface projection may have a concave shape in the width direction thereof. Due to the concave face, when external light such as, for example, sunlight is incident thereon, the light may be refracted to be diffused in the width direction, thereby enhancing the jewel-like brilliancy, as compared to a case in which the front surface projection is formed to have a convex shape so as to collect light. 
     The plurality of faces of the front surface projection may be successive in the circumferential direction along the front surface of the base. 
     The plurality of rear surface projections may include: a plurality of first projections, each of which is disposed on or adjacent to an optical axis of a corresponding one of the plurality of light sources; and a plurality of second projections, each of which is disposed between two adjacent first projections. A tip end of each of the plurality of first projections has a convex shape, and a tip end of each of the plurality of second projections has a concave shape. With this arrangement, each of the first projections may collect light mainly from one corresponding light source and each of the second projections may collect light obliquely incident thereon from two adjacent light sources, thereby uniformly illuminating the light guide. 
     The base of the light guide may have a cross-section, of which the front surface is convex. By forming the front surface projections on the curved surface, a three-dimensional effect may be enhanced. 
     The vehicular lamp may further include an inner lens inserted between the plurality of light sources and the light guide. By inserting the inner lens, the light from the light source may be incident on the light guide in a state where the light is diffused and the effective directivity of the light is diminished. Accordingly, a point light feeling may be reduced and the light may be uniformly emitted throughout the vehicular lamp. In addition, the light may be incident on the front surface projections from various directions and may be multi-reflected therein so that the jewel-tone brilliancy may be made conspicuous. 
     In the inner lens, cylindrical steps may be formed on the rear surface of the inner lens which faces the plurality of light sources, to be successive in the arrangement direction of the light sources. In this way, the light from the light sources may be properly diffused. 
     At least one of the plurality of front surface projections may be formed in an eleven-sided shape, except the bottom face thereof. 
     An area of the front surface of the base between each two adjacent projection forming areas may be subjected to a diffusion processing. Accordingly, a portion that emits light in a jewel tone and a portion that emits light in a matt tone may appear alternately. Thus, the jewel tone may further be enhanced due to the contrast between the portions. 
     The plurality of front surface projections may gradually vary in shape in the direction in the arrangement direction. In this way, the jewel tone suitable for a design of a vehicular lamp may be created. 
     Another aspect of the present disclosure relates to a vehicular lamp. The vehicular lamp includes: a plurality of light sources arranged in a row; a light guide configured to receive light emitted from the plurality of light sources on a rear surface thereof, and emit the light from a front surface thereof. The light guide includes: a base having a rear surface facing the plurality of light sources and extending in an arrangement direction of the plurality of light sources; and a plurality of front surface projections protruding from a front surface of the base. The plurality of front surface projections are arranged in the arrangement direction to be spaced apart from one another, and are formed in a plurality of projection forming areas, respectively. Each of the projection forming areas having a cross section, of which a side in a width direction of the base, which is perpendicular to the arrangement direction, becomes a longer side. Each of the plurality of front surface projections has a polyhedral shape including a plurality of faces that are successive in a circumferential direction thereof. 
     Meanwhile, optionally combining aforementioned components or substituting components or expressions of the present disclosure among, for example, a method, an apparatus, and a system, is also effective as an embodiment of the present disclosure. 
     According to the aspects of the present disclosure, a jewel-like brilliancy may be created. 
     The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a horizontal cross-sectional view illustrating a vehicular lamp according to an exemplary embodiment. 
         FIGS. 2A and 2B  are perspective views illustrating a light guide as viewed from a front surface side. 
         FIG. 3  is a perspective view illustrating a front surface projection of the light guide as viewed in a direction different from those of  FIGS. 2A and 2B . 
         FIG. 4  is a view illustrating a portion of the light guide as viewed from a rear surface side. 
         FIG. 5  is a view illustrating a positional relationship between the light guide and light sources. 
         FIG. 6  is a perspective view illustrating a front surface projection according to a modification. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, reference is made to the accompanying drawing, which form a part hereof. The illustrative embodiments described in the detailed description, drawing, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. In the following description and drawings, the same components will be denoted by the same reference numerals. 
       FIG. 1  is a horizontal cross-sectional view illustrating a vehicular lamp according to an exemplary embodiment. In the present exemplary embodiment, a tail lamp will be described as the vehicular lamp by way of an example. 
     The vehicular lamp  1  includes a lamp body  2 , a cover (outer lens)  4 , a plurality of light sources  10 , a support member  12 , a light guide  20 , and an inner lens  40 . The light sources  10 , the support member  12 , the light guide  20 , and the inner lens  40  are disposed within a lamp chamber formed by the lamp body  2  and the cover  4 . 
     The plurality of light sources  10  are arranged in a row to be spaced apart from each other according to a desired light emission pattern. An irradiation direction of the light sources  10  is aligned to face a front of the vehicular lamp  1  (a rear of a vehicle). The light sources  10  are semiconductor light sources such as, for example, light emitting diodes (LEDs) or semiconductor lasers, and are mounted on a flexible board  14 . The flexible board  14  is mounted to conform to the support member  12 . Thus, the plurality of light sources  10  are supported by the support member  12  in a stepped form. The light guide  20  receives a light emitted from the plurality of light sources  10  on the rear surface thereof, and outputs the light from the front surface thereof. 
     The inner lens  40  is inserted between the plurality of light sources  10  and the light guide  20  so as to diffuse the light emitted from the light source  10  by refraction and introduce the light into the rear surface of the light guide  20 . Cylindrical steps  44  may be formed on a rear surface  42  of the inner lens  40  which faces the plurality of light sources  10  to be successive in a direction D 1  in which the light sources  10  are arranged (hereinafter, referred to as an “arrangement direction D 1 ”). Through the cylindrical steps  44 , the light emitted from the plurality of light sources  10  may be appropriately diffused in a transverse direction so as to be uniformly introduced into the light guide  20 . The light emitted from the front surface of the light guide  20  is irradiated toward the rear side of the vehicle through the cover  4 . 
     Subsequently, descriptions will be made on a configuration of the light guide  20 . The light guide  20  includes a base  22 , a plurality of rear surface projections (rear surface ribs)  24 , and a plurality of front surface projections (front surface ribs)  26 . The base  22  has a reverse surface  22   a  extends in the arrangement direction of the light sources  10  (see, e.g., arrow D 1  in  FIG. 1 ) to face the plurality of light sources  10 . 
     The plurality of the rear surface projections  24  are formed to be directed toward the light sources  10  from the rear surface  22   a  of the base  22 . On the other hand, the plurality of front surface projections  26  are formed to be directed toward the irradiation direction of the light sources  10  (toward the rear side of the vehicle) from the front surface  22   b  of the base  22 . 
     The plurality of rear surface projections  24  are arranged to be spaced apart from each other and the plurality of front surface projections  26  are arranged to be spaced apart from one another, in the arrangement direction D 1  of the light sources  10 . The plurality of rear surface projections  24  and the plurality of front surface projections  26  are formed in a plurality of projection forming areas  28  of the base  22 . Each of the projection forming areas  28  has a cross section, in which a side in a width direction of the base  22  becomes a longer side. The width direction refers to a direction perpendicular to the arrangement direction D 1  and corresponding to the height direction of the vehicle (indicated by arrow D 2  in  FIG. 2A ). 
       FIGS. 2A and 2B  are perspective views illustrating the light guide  20  as viewed from the front surface side.  FIG. 2B  illustrates the front surface projections  26  as viewed in a direction opposite to that of  FIG. 2A . Each of the plurality of front surface projections  26  has a polyhedral shape. The polyhedral shape includes a plurality of faces (hereinafter, also referred to as circumferential faces) S 1  to S 5  which are successive in a circumferential direction (indicated by arrow D 3  in  FIG. 2A ) at least along the front surface  22   b  of the base  22 . In the present exemplary embodiment, the front surface projection  26  is formed in an eleven-sided shape (S 1  to S 11 ), except the bottom face thereof (the projection forming area  28 ), and in addition to circumferential faces S 1  to S 5 , includes side faces S 6  to S 8  and S 9  to S 11 . 
     An area  30  between each two adjacent projection forming areas  28  on the front surface  22   b  of the base  22  is subjected to a diffusion processing (embossing processing). 
       FIG. 3  is a perspective view illustrating a front surface projection  26  of the light guide  20  as viewed in a direction different from those of  FIGS. 2A and 2B . Among the circumferential faces S 1  to S 5 , the circumferential faces S 2  to S 4  that correspond to the front side when viewed from the rear side of the vehicle have a concave shape with respect to the width direction D 2  of the base  22 . The radius of curvature of the circumferential faces S 2  to S 4  may be, for example, about 10 cm. 
     As indicated by hatching in  FIG. 3 , the base  22  may have a curved cross section (hatched portion) in which the front surface  22   b  is convex and the rear surface  22   a  is concave. When the front surface projection  26  is formed on the convexly curved surface, a three-dimensional effect created by the front surface projection  26  is further enhanced. 
     Subsequently, descriptions will be made the rear surface projections  24 .  FIG. 4  is a view illustrating a portion of the light guide  20  as viewed from the rear surface side.  FIG. 5  is a view illustrating a positional relationship between the light guide  20  and the light sources  10 . The plurality of rear surface projections  24  include a plurality of first projections  24   a  and a plurality of second projections  24   b  which are alternately arranged in the arrangement direction D 1  of the light sources  10 . Each of the first projections  24   a  is disposed on or adjacent to the optical axis of corresponding one of the plurality of light sources  10 . Meanwhile, each of the second projections  24   b  is disposed between two adjacent first projections  24   a . Each of the tip ends of the plurality of first projections  24   a  has a convex shape, and each of the tip ends of the plurality of second projections  24   b  has a concave shape. In other words, by the first projections  24   a  and the second projections  24   b , convex steps and concave steps are alternately formed in the arrangement direction D 1  of the light sources  10 . 
     In the foregoing, the configuration of the vehicular lamp  1  has been described. Subsequently, descriptions will be made on an operation of the vehicular lamp  1 . 
     As illustrated in  FIG. 5 , the light emitted from the light source  10  is diffused by the inner lens  40  and is incident on the rear surface projections  24  of the light guide  20 . Due to the inserted inner lens  40 , each rear surface projection  24  receives light incident thereon at various angles. 
     The light incident on the rear surface projections  24  progresses toward the rear side of the vehicle while being multiple-reflected within the base  22 . In detail, a portion of the light is introduced into the front surface projections  26 , and the remainder of the light is leaked to areas other than the projection forming areas  28  of the base  22 . The light introduced into the front surface projections  26  is irradiated to the rear side of the vehicle through the front surfaces of the front surface projections  26 . In addition, the areas  30  emit light dimly due to the light leaked to the areas  30 . 
     With the vehicular lamp  1 , the following effects may be obtained. 
     When the vehicular lamp  1  is turned on, the light emitted from the light sources  10  and incident on the rear surface projections  24  is introduced into the front surface projection  26  and the light is multiple-reflected by the plurality of faces of the polyhedral front surface projections  26  such that surface emission with the jewel-like brilliancy and three-dimensional surface emitting may be realized. In addition, when the vehicular lamp  1  is turned off, external light such as, for example, sunlight, is multi-reflected from the plurality of faces of the polyhedral front surface projections  26  and is introduced into the front surface projections  26  to be multiple-reflected therein such that the jewel-like brilliancy may be realized. 
     In the vehicular lamp  1 , as illustrated in  FIG. 3 , the circumferential faces S 2 , S 3 , and S 4  of the front surface projection  26  have a concave shape in the width direction D 2 . Thus, when the external light such as, for example, sunlight, is incident on the front surface projection  26 , the light is refracted to be diffused with respect to the width direction D 2 , and the jewel-like brilliancy may be enhanced, as compared to a case in which an front surface projection has convex faces in the width direction D 2  so as to collect light. 
     In the vehicular lamp  1 , as illustrated in  FIG. 5 , the rear surface projections  24  are arranged such that the first projections  24   a  and the second projections  24   b  are alternately arranged. Thus, each first projection  24   a  may collect the light mainly emitted from one light source  10 , of which the optical axis is shared with the first projection  24   a , and each second projection  24   b  may collect the light obliquely incident thereon from two adjacent light sources  10  so that the light guide  20  may be uniformly illuminated. In other words, in the present exemplary embodiment, regular and uniform light emission may be achieved by a relatively small number of light sources  10 , as compared to a case in which the number of rear surface projections  24  is the same as the number of light sources  10  so that the rear surface projections  24  and the light sources  10  are in a one-to-one correspondence. In addition, by disposing two front surface projections  26  with respect to one light source  10 , the jewel tone brilliancy may further be enhanced. 
     As illustrated in  FIG. 3 , the base  22  is formed to have a curved cross section so that its front surface  22   b  has a convex shape. By forming the front surface projection  26  on such a curved surface of the base  22 , the three-dimensional effect may be enhanced. 
     In addition, by inserting the inner lens  40  between the plurality of light sources  10  and the light guide  20 , the light emitted from the light source  10  may be diffused in multi-directions and effective directivity may be diminished. Accordingly, the point light feeling may be reduced, and the vehicular lamp  1  may emit light uniformly. Moreover, since the light is incident on the front surface projection  26  in various directions and is multiple-reflected therein, the jewel-like brilliancy may be made conspicuous. 
     The aforementioned jewel-like brilliancy or three-dimensional effect may contribute to creating a high quality feeling in the vehicle and produce a relatively high added value, in addition to the original function of the vehicular lamp  1  of increasing the safety of the vehicle. 
     The areas  30  between the projection forming areas  28  of the obverse surface  22   b  of the base  22  are subjected to an embossing process. Through the embossing process, the portions emitting light in a jewel tone (the projection forming areas  28 ) and the portions emitting light in a matt tone (the areas  30  between the projection forming areas  28 ) appear alternately, and due to the contrast therebetween, the jewel tone may be further enhanced and the three-dimensional effect may be created. 
     The present disclosure has been described above based on an exemplary embodiment. It may be understood by a person ordinarily skilled in the art that the exemplary embodiment is provided merely for the purposes of illustration, and that various modifications may be made through a combination of respective components and the modifications also belong to the scope of the present disclosure. Hereinafter, such modifications will be described. 
     (Modification 1) 
     While the exemplary embodiment described above forms the front surface projection  26  in an eleven-sided shape, the shape of the front surface projection  26  is not limited thereto. For example, side faces S 6  to S 8  may form a single plane, and similarly, side faces S 8  to S 11  opposite to the side faces S 6  to S 8  may also form a single plane. 
     (Modification 2) 
       FIG. 6  is a perspective view illustrating a front surface projection  26  according to a modification. As illustrated in  FIG. 6 , the number of circumferential faces of the front surface projection  26  which are successive in the circumferential direction D 3  of the front surface projection  26  may be four. In this case, the front surface projection  26  may have an eight-sided shape, except the bottom face thereof. Alternatively, the number of faces that are successive in the circumferential direction D 3  may be six or more. 
     It may be appreciated that the aforementioned jewel-tone brilliancy is created by edges E 1  to E 4  defining boundaries of the circumferential faces S 1  to S 5  (S 1  to S 4 ) of  FIGS. 2A and 2B , and edges E 1  to E 3  defining boundaries of circumferential faces S 1  to S 4  of  FIG. 6 . In this regard, the number of edges defining boundaries of the circumferential faces may be at least two, and more particularly, three or more. 
     Alternatively, the front surface projection  26  of  FIG. 6  and the front surface projection  26  of  FIG. 2  may be used in combination. In addition, in a case where front surface projections  26  having different shapes are formed in combination, the shapes of the plurality of front surface projections  26  may gradually and successively vary in the arrangement direction D 1  of light sources  10 . Accordingly, different jewel tones, in which a portion of a vehicular lamp  1  has a fine jewel tone and another portion of the vehicular lamp  1  has a rough jewel tone, may be created. 
     (Modification 3) 
     In a case where the directivity of the light sources  10  is not so strong, the inner lens  40  may be omitted. 
     (Modification 4) 
     Although a tail lamp has been described as one type of the vehicular lamp  1  in the exemplary embodiment described above, the present disclosure may be applied to a rear combination lamp which is disposed in a corner of a vehicle. 
     From the foregoing, it will be appreciated that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the following claims.