Abstract:
A lighting fixture projects light sideward and has no restriction in design. The lighting fixture can include an LED; a primary lens disposed in an optical axis of the LED, the primary lens being configured to form a main light distribution; an auxiliary lens disposed on an outer peripheral side of the primary lens around the optical axis of the LED; and a reflecting portion configured to reflect part of light emitted from the LED to substantially an entire area of the auxiliary lens on an inner peripheral surface side thereof. The reflecting portion can be formed integrally with the primary lens and include an incident surface on which part of light emitted from the LED can be incident, a reflecting surface configured to reflect light having entered through the incident surface, and a light-exiting surface configured to allow the light reflected by the reflecting surface to exit.

Description:
[0001]    This application claims the priority benefit under 35 U.S.C. §119 of Japanese Patent Application No, 2015-153077 filed on Aug. 3, 2015, which is hereby incorporated in its entirety by reference. 
       TECHNICAL FIELD 
       [0002]    The presently disclosed subject matter relates to a light guiding body that can project light by reflecting light during guiding process of light emitted from a light source as well as a vehicle lighting fixture using the same. 
       BACKGROUND ART 
       [0003]    Light emitting diodes (LEDs) having advantages, such as high light emission efficiency, high luminance, and electric power saving, have been widely utilized as light sources for vehicle lighting fixtures, such as turn signal lamps, rear lamps, stop lamps, etc. to be disposed on left and right sides of the rear portion of a vehicle body. Such an LED can emit light with strong directivity. Thus, in such a vehicle lighting fixture using the LED, the light with strong directivity is tried to be guided through a light guiding body so that the entire light guiding body can project light (the entire light guiding body can be illuminated with light). Specifically, such a light guiding body can project light (can be illuminated with light) by means of the following mechanism. That is, a light source can be disposed to face to the light guiding body with its incident surface opposed to the light source, and the light emitted from the light source can enter the light guiding body through the incident surface to an opposite side of the light guiding body to the incident surface side. Since the light guiding body can include a reflecting portion formed on a back surface, when the light having entered the light guiding body is guided (travels) through the light guiding body, part of the light can be totally reflected by the reflecting portion on the back surface to thereby be projected through a front surface of the light guiding body. In this manner, the light can be projected through the entire front surface of the light guiding body (the light guiding body can be entirely illuminated with the light through the front surface). 
         [0004]    A conventional vehicle lighting fixture using a light guiding body will be described on the basis of  FIGS. 1 and 2 . 
         [0005]      FIG. 1  is a front view of a conventional vehicle lighting fixture  101  and  FIG. 2  is a cross-sectional view of the vehicle lighting fixture  101  taken along line BB in  FIG. 1 . The illustrated vehicle lighting fixture  101  can be used as a turn signal lamp to be disposed on left and right sides of a vehicle body. 
         [0006]    As illustrated in  FIG. 2 , the vehicle lighting fixture  101  to be used as a turn signal lamp can include a housing  102  having an opening and a transparent outer lens  103  configured to cover the opening of the housing  102  to define a lighting chamber  104 . The vehicle lighting fixture  101  can further include a plurality of LEDs  105  (five LEDs in the illustrated example) as light sources, a light guiding body  106 , an extension  107 , etc., which are housed in the lighting chamber  104 . 
         [0007]    The vehicle lighting fixture  101  can further include an elongated substrate  108  which is disposed laterally (in a left-right direction in  FIG. 1 ) at the upper portion within the lighting chamber  104  and on which the plurality of LEDs  105  are mounted at predetermined intervals so that the LEDs  105  can emit light downward. 
         [0008]    The light guiding body  106  can be formed in a plate shape from a transparent resin such as an acrylic resin or a polycarbonate resin having light-guiding properties. The light guiding body  106  can include an incident surface  106   a  facing to the LEDs  105  at its upper surface and a light exiting surface  106   b  at its front surface. Furthermore, as illustrated in  FIG. 2 , the light guiding body  106  can be formed to be stepwisely thinned from a side of the incident surface  106   a  to its lower end side (an opposite side to the incident surface). In the illustrated example, there can be formed three reflecting portions  106   c  each having a reflecting surface at respective boundary portions of a rear surface of the light guiding body  106  where the thickness of the light guiding body  106  is stepwisely changed as illustrated in  FIGS. 1 and 2 . The reflecting portions  106   c  can be parallel with each other in the vertical direction while being curved obliquely rightward and upward in  FIG. 1 . 
         [0009]    In the illustrated example, the housing  102  and the extension  107  can be integrally formed by an opaque resin that cannot transmit light so that the extension  107  can cover the LEDs  105 , the substrate  108 , and peripheries of the light guiding body  106 . 
         [0010]    In the vehicle lighting fixture  101  with the above-described configuration, when the plurality of LEDs  105  are supplied with a current to emit light, the light emitted downward from the LEDs  105  can enter the light guiding body  106  through the incident surface  106   a  of the light guiding body  106  as illustrated in  FIG. 2 . Then, as the light having entered the inside of the light guiding body  106  can travel (be guided) downward, part of the light can be totally reflected by the respective reflecting surfaces of the reflecting portions  106   c  formed in the rear surface of the light guiding body  106  to the front surface side (leftward in  FIG. 2 ). Thus, the reflected light can be projected through the light exiting surface  106   b  and then through the transparent outer lens  103  forward, so that the three reflecting portions  106   c  of the light guiding body  106  can be observed as being illuminated with light in a curved manner when viewed from its front side. 
         [0011]    Furthermore, Japanese Patent Application Laid-Open No. 2008-097923 proposes a vehicle lighting fixture using a light guiding body, which is illustrated in  FIGS. 3 and 4 . 
         [0012]      FIG. 3  is a perspective view of the light guiding body  206  used in the vehicle lighting fixture proposed in Japanese Patent Application Laid-Open No. 2008-097923, and  FIG. 4  is a front view illustrating an optical path within the light guiding body  206  of  FIG. 3 . The light guiding body  206  includes a first light guiding portion  206 A, a light inverting portion  206 B, a second light guiding portion  206 C, and a light reflecting portion  206 D. 
         [0013]    Specifically, the first light guiding portion  206 A can include an incident surface  206   a  at its longitudinal end to be opposed to a not-illustrated light source. The light inverting portion  206 B is formed at an opposite longitudinal end of the first light guiding portion  206 A and the second light guiding portion  206 C. The light inverting portion  206 B includes two inclined reflecting surfaces  206   b  and  206   c  so as to provide a function of inverting the traveling direction of parallel light rays guided from the first light guiding portion  206 A. 
         [0014]    The second light guiding portion  206 C is thinned from the opposite longitudinal end side, and the light reflecting portion  206 D is formed on the entire rear surface of the second light guiding portion  206 C in the longitudinal direction by forming a plurality of triangular prism cuts disposed side by side in the longitudinal direction. 
         [0015]    In the light guiding body  206  with the above-described configuration, when the not-illustrated light source is turned on to emit light, the light can enter the light guiding body  206  through the incident surface  206   a  of the first light guiding portion  206 A to travel through the first light guiding portion  206 A to the light inverting portion  206 B. Then the light can be totally reflected by the reflecting surfaces  206   b  and  206   c  of the light inverting portion  206 B to invert the traveling direction by 180°. The light travelling in the inverted direction through the second light guiding portion  206 C can be reflected by the light reflecting portion  2061 ) to be projected through the front surface (light exiting surface) of the second light guiding portion  206 C. Thus, when observed from its front side, the light reflecting portion  2061 ) can be observed as being illuminated with light. 
         [0016]    Problems in association with such conventional techniques will now be discussed. 
         [0017]    In the vehicle lighting fixture  101  illustrated in  FIGS. 1 and 2 , the light with strong directivity from the respective LEDs  105  as represented by L 1  in  FIG. 1  can travel downward through the light guiding body  106  while being diffused in a triangular front shape. Such light L 1  directly reaching the respective reflecting portions  106   c  can be totally reflected by the respective reflecting portions  106   c  to be projected through the front light exiting surface  106   b . In this case, the light L 1  cannot reach the parts of the reflecting portions  106   c  of the light guiding body  106  closer to the LEDs  105 , so that the reflected light rays can be separately projected and thus darkened portions may be generated (occurring uneven illuminance). Incidentally, it is difficult to dispose LEDs  105  on the opposite side (lower side in the drawings) from the viewpoint of general problems in association with processing vehicle bodies. 
         [0018]    In the light guiding body  206  illustrated in  FIGS. 3 and 4 , since the light travelling through the first light guiding portion  206 A is returned by the light inverting portion  206 B (the travelling direction is inverted), the light guiding body  206  can project light as if the light source is disposed on the opposite side to the actual disposition side. However, the light can be projected only from the light reflecting portion  206 D of the second light guiding portion  206 C and the light guiding body  206  is thick by the thickness of the first light guiding portion  206 A, resulting in enlarged size of the entire light guiding body  206 . Specifically, as illustrated in  FIG. 4 , the light guiding body  206  has a thickness t being constant in the longitudinal direction while the light projecting portion or the second light guiding portion  206 C has a half of the thickness t. 
       SUMMARY 
       [0019]    The presently disclosed subject matter was devised in view of these and other problems and features in association with the conventional art. According to an aspect of the presently disclosed subject matter, a light guiding body can project light uniformly while achieving effective use of light from a light source without loss. Furthermore, there can be provided a vehicle lighting fixture using such a light guiding body. 
         [0020]    According to another aspect of the presently disclosed subject matter, a light guiding body can include: an incident surface configured to face to a light source on one end side; an inverting portion provided on the other end side opposite to the incident surface, the light entering the light guiding body through the incident surface being guided through the light guiding body toward the inverting portion, the inverting portion configured to invert a travelling direction of light guided from the incident surface; and a rear surface and a front surface connecting the incident surface and the inverting portion, the rear surface having reflecting portions formed therein so that the reflecting portions can totally reflect the light toward the front surface, which serves as a light exiting surface. This light guiding body with this configuration can be formed to be stepwisely thickened from a side of the incident surface (the one end side) to a side of the inverting portion (the other end side), so that the rear surface can have the reflecting portions at respective boundary portions where a thickness of the light guiding body is stepwisely changed. The light emitted from the light source can enter the light guiding body through the incident surface and travel through the light guiding body to the inverting portion, and be returned to the side of the incident surface by the inverting portion, and part of the returned light can be reflected by each of the reflecting portions of the rear surface to be projected forward through the front surface. 
         [0021]    In the light guiding body with this configuration, the inverting portion may be subjected to a light diffusion treatment. 
         [0022]    In the light guiding body with any of the above-described configurations, the reflecting portions may be subjected to light diffusion treatment. 
         [0023]    According to still another aspect of the presently disclosed subject matter, a vehicle lighting fixture can include a housing having an opening; an outer lens configured to cover the opening of the housing to define a light chamber together with the housing; and a light source and the light guiding body with any of the above-described configurations, which can be housed in the lighting chamber. 
         [0024]    In the vehicle lighting fixture with this configuration, an inner surface of the housing opposed to the light guiding body may be subjected to reflection treatment. 
         [0025]    In the light guiding body with the main configuration as described above, the light can enter the light guiding body through the incident surface and straightforwardly travel within the light guiding body to reach the inverting portion. Then, the traveling direction of the light can be inverted by the inverting portion so that the light can travel through the light guiding body from the inverting portion toward the incident surface in the inverted travelling direction. During this inverted travelling, part of the light can be totally reflected by each of the reflecting portions provided at the respective boundary portions where the thickness of the light guiding body changes. In this manner, the light can be projected from the reflecting portions forward. In the light guiding body, since the light returned by the inverting portion can be still diffused while travelling in the inverted traveling direction, the substantially entire area of each of the reflecting portions can receive the returned light to totally reflect the light. This is because the light from the light source to the reflecting portions can travel through sufficiently long traveling paths and thus the light can be sufficiently diffused. This can prevent darkened portions from being generated while providing uniform light emission from the entire reflecting portions. Furthermore, since the stepwise thickening of the light guiding body is achieved from the side of the incident surface toward the inverting portion, the leakage of light to the outside of the light guiding body can be prevented. Furthermore, the stepwise thinning of the light guiding body in the inverted travelling direction of light can ensure the light to impinge on the plurality of reflecting surfaces stepwisely. 
         [0026]    Furthermore, the light guiding body with the inverting portion subjected to the light diffusion treatment can promote the diffusion of light toward the reflecting portions in the inverted travelling direction. This can enhance the uniform light emission from the reflecting portions, and also effectively prevent the occurrence of the darkened portion. 
         [0027]    The light guiding body with the reflecting portions subjected to the light diffusion treatment can achieve the uniform light emission from the reflecting portions and effectively prevent the occurrence of the darkened portion. 
         [0028]    The vehicle lighting fixture with the above-described configuration can emit light uniformly and improve the appearance of the entire lighting fixture during light emission. 
         [0029]    In the vehicle lighting fixture with the housing inner surface being subjected to the reflection treatment, even when the light is leaked through the rear surface of the light guiding body, the light can be reflected by the reflection treated inner surface of the housing opposed to the light guiding body and enter the light guiding body again. This re-entering light can be used for light emission from the light guiding body, resulting in enhanced light utilization efficiency. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0030]    These and other characteristics, features, and advantages of the presently disclosed subject matter will become clear from the following description with reference to the accompanying drawings, wherein: 
           [0031]      FIG. 1  is a front view of a conventional vehicle lighting fixture; 
           [0032]      FIG. 2  is a cross-sectional view of  FIG. 1  taken along line B-B; 
           [0033]      FIG. 3  is a perspective view of a light guiding body to be used in a vehicle lighting fixture proposed in Japanese Patent Application Laid-Open No. 2008-097923; 
           [0034]      FIG. 4  is a front view illustrating travelling paths of light within the light guiding body of  FIG. 3 ; 
           [0035]      FIG. 5  is a front view of a vehicle lighting fixture made in accordance with principles of the presently disclosed subject matter; 
           [0036]      FIG. 6  is a cross-sectional view of the vehicle lighting fixture of  FIG. 5  taken along line A-A; and 
           [0037]      FIG. 7  is a cross-sectional view of part of an inverting portion of a light guiding body in another exemplary embodiment made in accordance with the principles of the presently disclosed subject matter. 
       
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0038]    A description will now be made below to light guiding bodies and vehicle lighting fixtures of the presently disclosed subject matter with reference to the accompanying drawings in accordance with exemplary embodiments. Herein, the directions shall be based on the posture of the vehicle lighting fixture mounted on a vehicle lighting body with the light emitting direction being forward. 
         [0039]      FIG. 5  is a front view of a vehicle lighting fixture  1  made in accordance with the principles of the presently disclosed subject matter, and  FIG. 6  is a cross-sectional view of the vehicle lighting fixture  1  of  FIG. 5  taken along line A-A. The illustrated vehicle lighting fixture  1  can be used as a turn signal lamp to be disposed on right and left side of a vehicle body. Because the basic structure is common to both right and left turn signal lamps, one vehicle lighting fixture  1  will be described. 
         [0040]    As illustrated in  FIG. 5 , the vehicle lighting fixture  1  to be used as a turn signal lamp can include a housing  2  having an opening and a transparent outer lens  3  configured to cover the opening of the housing  2  to define a lighting chamber  4 . The vehicle lighting fixture  1  can further include a plurality of LEDs  5  (five LEDs in the illustrated example) as light sources, a light guiding body  6  (also being one aspect of the presently disclosed subject matter), an extension  7 , etc., which can be housed in the lighting chamber  4 . 
         [0041]    The vehicle lighting fixture  1  can further include an elongated substrate  8  which can be disposed laterally (in a left-right direction in  FIG. 5 ) at the upper portion within the lighting chamber  4  and on which the plurality of LEDs  5  are mounted at predetermined intervals so that the LEDs  5  can emit light downward, as illustrated in  FIG. 5 . 
         [0042]    The light guiding body  6  made in accordance with the principles of the presently disclosed subject matter can be formed in a plate shape from a transparent resin such as an acrylic resin or a polycarbonate resin having light-guiding properties. The light guiding body  6  can include an incident surface  6   a  facing to the LEDs  5  at its upper surface and a light exiting surface  6   b  at its front surface. Furthermore, as illustrated in  FIG. 6 , the light guiding body  6  can be formed to be stepwisely thickened from a side of the incident surface  6   a  to its lower end side (an opposite side to the incident surface  6   a ). In the illustrated example, there can formed three reflecting portions  6   c  each having a reflecting surface at respective boundary portions of a rear surface of the light guiding body  6  where the thickness of the light guiding body  6  is stepwisely changed as illustrated in  FIGS. 5 and 6 . The reflecting portions  6   c  can be parallel with each other in the vertical direction while being curved obliquely rightward and upward in  FIG. 5 . Each of the reflecting surfaces of the reflecting portions  6   c  can be a totally reflecting surface that can totally reflect light. 
         [0043]    Furthermore, the light guiding body  6  can include an inverting portion  6 A at an opposite end to the incident surface  6   a  where the thickness is the thickest (at the lower end portion in the drawings). The light inverting portion  6 A includes two inclined reflecting surfaces  6   d  and  6   e  so as to provide a function of inverting the traveling direction of parallel light rays guided through the light guiding body  6  (function of returning the light in an inverted travelling direction). In the illustrated exemplary embodiment, the inverting portion  6 A can take a triangular prism shape, but is not limited to this. As illustrated in  FIG. 7 , the inverting portion  6 A may be constituted by a plurality of small triangular prisms configured to return the light in the inverted travelling direction. 
         [0044]    Furthermore, the housing  2  and the extension  7  can be integrally formed by an opaque resin that cannot transmit light so that the extension  7  can cover the LEDs  5 , the substrate  8 , and peripheries of the light guiding body  6 . 
         [0045]    In the illustrated exemplary embodiment, the inverting portion  6 A and the reflecting portions  6   c  can be subjected to light diffusion treatment such as formation of cuts or surface texturing. Furthermore, the housing  2  can have an inner surface  2   a  opposed to the rear surface of the light guiding body  6 , with the inner surface  2   a  being subjected to reflection treatment such as aluminum deposition. 
         [0046]    In the vehicle lighting fixture  1  with the above-described configuration, when the plurality of LEDs  5  are supplied with a current to emit light downward, the light with strong directivity from the respective LEDs  5  can enter the light guiding body  6  through the incident surface  6   a  thereof. Then, the light having entered the light guiding body  6  can travel downward to the inverting portion  6 A while being diffused in a triangular front shape as represented by L 1  in  FIG. 5 . Then the light L 1  can be totally reflected by the reflecting surfaces  6   d  and  6   e  of the inverting portion  6 A to invert the traveling direction by 180°. The light still diffused in a triangular front shape can travel upward in the inverted direction as represented by L 2  in  FIG. 5 . During travelling, part of the light can be totally reflected by the respective reflecting surfaces of the reflecting portions  6   c  formed in the rear surface of the light guiding body  6  to the front surface side (leftward in  FIG. 6 ). Thus, the reflected light can be projected through the light exiting surface  6   b  and then through the transparent outer lens  3  forward, so that the three reflecting portions  6   c  of the light guiding body  6  can be observed as being illuminated with light in a curved manner when viewed from its front side. 
         [0047]    In this exemplary embodiment, the light L 1  can enter the light guiding body  6  through the incident surface  6   a  and straightforwardly travel within the light guiding body  6  downward to reach the inverting portion  6 A. Then, the traveling direction of the light L 1  can be inverted by the inverting portion  6 A so that the light L 2  can travel through the light guiding body  6  from the inverting portion  6 A toward the incident surface  6   a  in the inverted travelling direction (upward). During this inverted travelling, part of the light L 2  can be totally reflected by each of the reflecting portions  6   c  provided at the respective boundary portions where the thickness of the light guiding body  6  changes. In this manner, the light L 2  can be projected from the reflecting portions  6   c  forward. In the light guiding body  6 , since the light L 2  returned by the inverting portion  6 A can be still diffused while travelling in the inverted traveling direction (upward), the substantially entire area of each of the reflecting portions  6   c  can receive the returned light to totally reflect the light. This is because the light from the LEDs  5  to the reflecting portions  6   c  of the light guiding body  6  can travel through sufficiently long traveling paths and thus the light can be sufficiently diffused. This can prevent darkened portions from being generated while providing uniform light emission from the entire reflecting portions  6   c . Accordingly, the vehicle lighting fixture  1  to be used as a turn signal lamp can emit light uniformly and improve the appearance of the entire vehicle lighting fixture  1  during light emission. Furthermore, since the stepwise thickening of the light guiding body  6  is achieved from the side of the incident surface  6   a  toward the inverting portion  6 A, the leakage of light to the outside of the light guiding body  6  can be prevented. Furthermore, the stepwise thinning of the light guiding body in the inverted travelling direction of light can ensure the light to impinge on the plurality of reflecting surfaces stepwisely. 
         [0048]    Furthermore, the light guiding body  6  according to this exemplary embodiment with the inverting portion  6 A subjected to the light diffusion treatment can promote the diffusion of light L 2  toward the reflecting portions  6   c  in the inverted travelling direction. This can enhance the uniform light emission from the reflecting portions  6   c , and also effectively prevent the occurrence of the darkened portion. 
         [0049]    The light guiding body  6  with the reflecting portions  6   c  subjected to the light diffusion treatment can achieve the uniform light emission from the reflecting portions  6   c  and effectively prevent the occurrence of the darkened portion. 
         [0050]    In the vehicle lighting fixture  1  with the inner surface  2   a  of the housing  2  being subjected to the reflection treatment such as aluminum deposition, even when the light is leaked through the rear surface of the light guiding body  6 , the light can be reflected by the reflection treated inner surface  2   a  of the housing  2  opposed to the light guiding body  6  and enter the light guiding body  6  again. This re-entering light can be used for light emission from the light guiding body  6 , resulting in enhanced light utilization efficiency. 
         [0051]    Note that the vehicle lighting fixture made in accordance with the principles of the presently disclosed subject matter can be used not only as a turn signal lamp, but also any other vehicle lighting fixtures, such as rear lamps, stop lamps, reverse lamps, positioning lamps, etc. Furthermore, the light source used in the vehicle lighting fixture of the presently disclosed subject matter is not limited to LEDs, but may be bulbs and the like light sources. 
         [0052]    It will be apparent to those skilled in the art that various modifications and variations can be made in the presently disclosed subject matter without departing from the spirit or scope of the presently disclosed subject matter. Thus, it is intended that the presently disclosed subject matter cover the modifications and variations of the presently disclosed subject matter provided they come within the scope of the appended claims and their equivalents. All related art references described above are hereby incorporated in their entirety by reference.