Abstract:
A distributed lighting system comprising a waveguide assembly that includes a vehicle interior trim panel having an elongated opening therein and a correspondingly elongated waveguide attached to the trim panel to provide laterally-directed illumination through the opening along the length of the waveguide. The waveguide is attached to the trim panel using a support frame that includes a light-transmissive lower wall which fits within the opening and a pair of opposed side walls that, together with the lower wall, define a channel in which the waveguide is located. The waveguide includes a light-scattering region located opposite the opening in the trim panel to direct light laterally out of the waveguide and through the opening. The waveguide assembly also includes a back cover that encloses the waveguide between the cover and support frame. Different waveguide cross-sections and light-scattering configurations are disclosed.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority from Provisional Application No. 60/115,830, filed Jan. 14, 1999, and entitled “DISTRIBUTED LIGHTING SYSTEM,” which is incorporated by reference. 
    
    
     TECHNICAL FIELD 
     This invention relates generally to lighting systems for automotive vehicles and more particularly to distributed lighting systems wherein light from a remote source is transmitted via a waveguide to desired areas within the interior of the vehicle. 
     BACKGROUND OF THE INVENTION 
     Distributed lighting systems (DLS&#39;s) are sometimes used in automotive interior lighting applications for directing light from a central source via optical fibers or other waveguides to illuminate selected areas of the interior of the vehicle. Many of such applications are directed toward illuminating instrument panels, controls, and the like in lieu of providing individual light sources for each location, such as incandescent or LED lamps. 
     In some instances, these distributed lighting systems use waveguides to route light to a remote location where it is emitted out of the end of the waveguide to provide back lighting or to provide illumination within the vehicle interior. Control of the light emitted from the ends of the waveguides can be accomplished using lenses or other optical elements. Rather than using a waveguide simply to carry light to a remote location, it is known to provide notches and other such surface features along the length of the waveguide to promote the lateral emission of light from the waveguide. See, for example, U.S. Pat. No. 5,845,038 to D. J. Lundin et al. As indicated in U.S. Pat. No. 5,659,643 to R. H. Appeldorn et al., it is also known to use waveguides of varying cross-sectional shape for this purpose. 
     To properly provide lengthwise illumination in a vehicle application using waveguides, some type of practical mounting assembly is required that permits the waveguide to be securely mounted in place while maintaining the desired illumination characteristics for the intended application. Accordingly, it is a general object of the invention to provide a directed lighting system which is particularly advantageous for use in connection with interior trim panels such as headliners, door panels, seat panels, visors, and the like to illuminate the cabin of a vehicle, including the floor of the vehicle, to provide an aesthetically pleasing yet effective illumination of the interior of the vehicle. 
     SUMMARY OF THE INVENTION AND ADVANTAGES 
     According to the invention, a distributed lighting system is provided having an elongated waveguide fabricated of light-transmissive material mounted on a support frame having a protective light-transmissive lens adjacent the waveguide opposite a light-scattering region of the waveguide for transmitting the light scattered by the region through the lens portion to light the interior of a vehicle. 
     The support frame is constructed to mount to an interior panel of a vehicle, such as a headliner, door panel, instrument panel, seat panel, or the like with the lens region of the support frame extending through a correspondingly shaped opening in the interior trim panel and the waveguide supported and concealed beneath the panel. The support frame is secured by suitable means to the trim panel, such as by mechanical fasteners, self-retaining connectors, or the like. 
     A reflective backing cover preferably extends and shrouds an exposed back surface region of the waveguide opposite the lens for redirecting any light that would otherwise escape through the back surface back into the waveguide for transmission through the lens. The cover may advantageously have connecting portions cooperating with associated connecting portions of the support frame for securing the waveguide within the channel. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features and advantages of the present invention will become more readily appreciated when considered in connection with the following detail description and appended drawings, wherein: 
     FIG. 1 is an exploded fragmentary perspective view of a distributed lighting system constructed according to a first presently preferred embodiment of the invention; 
     FIG. 2 is an enlarged cross-sectional view of the assembled components of FIG. 1 taken generally along lines  2 — 2  of FIG. 1; 
     FIGS. 3-5 are three alternative cross-sectional shapes that may be employed with the waveguide in lieu of the circular shape illustrated in the preceding figures; 
     FIG. 6 is still a further alternative construction of a waveguide having a variable width light-scattering region; and 
     FIG. 7 is yet another embodiment of a waveguide having integrated mounting features. 
    
    
     DETAILED DESCRIPTION 
     A distributed light system (DLS) constructed according to a first presently preferred embodiment of the invention is shown generally at  10  in FIGS. 1 and 2 and comprises a waveguide  12  extending longitudinally between a light input end  14  and an opposite end  16  and being fabricated of a solid body of light-transmissive material such as acrylic or the like. 
     The DLS  10  includes a support frame  18  having a lower wall  20  and opposite laterally spaced side walls  22  defining a longitudinally extending channel  24  in which the waveguide  12  is disposed. At least the lower wall  20  and preferably the entire support frame  18  is fabricated of a light-transmissive material such as acrylic so that the lower wall  20  serves as a protective light-transmitting lens for the waveguide  12 , as will be explained in greater detail below. 
     As shown best in FIG. 2, the side walls  22  preferably have a stepped profile defining opposite longitudinally extending outer shoulders  26  adjacent the lens  20 . The stepped shoulders  26  enable the support frame  18  to be mounted on an interior trim panel  28  of an automotive vehicle with the lens portion  20  of the frame  18  projecting into a correspondingly shaped opening  30  in the panel  28 . The panel  28  may comprise a headliner, a door panel, seat panel, visor, instrument panel, etc. With such an arrangement, only the lens portion  20  of the frame  18  is visible on the finished interior side  32  of the trim panel  28 . The remaining portions of the frame  18  and components of the DLS  10  are disposed and concealed behind the panel  28  on a back side  34  thereof. 
     The support frame  18  is provided with some means of securing the frame  18  and thus the DLS  10  to the panel  28 . It will be appreciated that any of a number of fastening systems commonly used in the interior trim and lighting art may be employed, and may include a variety of mechanical fastening systems such as spring clips, self-retaining locking projections, adhesives, or simply screws  36 , as illustrated in the drawings. The screws  36  extend through openings provided in screw mount portions  38  of the frame  18  projecting laterally outwardly of the side walls  22  on opposite sides of the channel  24  adjacent the shoulders  26  and are operative for securing the frame  18  to the trim panel  28  in the manner illustrated in FIG.  2 . It will be appreciated from FIG. 1 that the frame  18  may be provided with a plurality of such screw mount portions  38  provided at spaced locations along the length of the frame  18 . 
     One way of securing the waveguide  12  within the channel  24  of the frame  18  is by provision of a back cover  40  which fits over an exposed back side portion  42  of the waveguide  12  and is secured to the frame  18  thereby capturing the waveguide  12  between the frame  18  and cover  40  as shown best in FIG.  2 . For purposes of securing the cover  40  to the frame  18 , the cover may have similar screw mount portions  44  projecting from opposite lateral sides of the cover in alignment with the screw mount portions  38  of the frame  18  to accommodate the reception of the screws  36 , such that the cover  40  may be simultaneously joined to the frame  18  and secured to the panel  28  via the screws  36 . It will be appreciated, however, that any of a number of means may be employed to secure the cover  40  to the frame  18 , such as adhesives, interlocking portions, welding, etc. Unlike the lens portion  20  of the frame  18 , the cover  40  is non-transmissive of light (i.e., is opaque) and preferably has a reflective inner surface  46  that conforms closely in size and shape to that of the back side portion  42  of the waveguide  12  so as to redirect any light rays that would otherwise escape through the back side portion  42  of the waveguide  12  back into the waveguide  12  for transmission through the lens  20 . 
     The waveguide  12  is operatively coupled at its light input end  14  to a source of light  48 . The light source  48  may comprise an incandescent or LED lamp, or input from optical fibers or another waveguide. It is contemplated that the DLS  10  may thus comprise either a stand alone light system having its own light source  48  for directing light into the waveguide  12  through the input end  14 , or may comprise a section of an overall larger distributed lighting system in which case the DLS  10  of the invention may comprise one of several branches of a multi-branch distributed lighting system of a vehicle. 
     The light which enters the waveguide  12  from the light source  48  is transmitted therealong toward the opposite end  16 , and during its passage is reflected off the outer surface  50  of the waveguide  12  interiorly thereof according to known principles. To achieve internal reflection, the outer surface  50  of the waveguide  12  is generally smooth and free of imperfections that would act to defract the light. According to the invention, however, a select region  52  of the outer surface  50  of the waveguide  12  opposite the lens  20  is roughened such that the light encountering the region  52  is scattered. Some of the scattered light rays are directed toward the opposite side of the waveguide  12  where they are transmitted out of the waveguide  12  and through the lens  20  into an interior compartment  54  of a vehicle  56 . The roughened light-scattering region  52  extends longitudinally of the waveguide  12  and, in the illustrated embodiment, is continuous between the ends  14 ,  16  of the waveguide  12 . It is contemplated that there may be applications in which it may not be necessary or desirable to transmit the light from the waveguide  12  over its entire length, and in such instances the roughened light-scattering regions  52  may be interrupted by intervening smooth surface sections  50  along which the light would be internally reflected rather than transmitted out of the waveguide  12 . 
     Any of a number of techniques may be employed to form the light-scattering region  52 , and may include molding a roughened region  52  into the waveguide  12  during its formation, or by any of a number of post forming operations such as bead blasting, scribing, application of light-defracting tape, or other means which would act to scatter the light rays that encounter the region  52  so as to direct at least some of the defracted rays through the lens  20 . 
     It will be observed from FIG. 2 that the light-scattering region  52  is straddled on either lateral side by smooth light-reflecting portions  50  of the outer surface which reflect and redirect the light inwardly of the waveguide with minimal scattering. Restricting the width and location of the light-scattering region  52  relative to the lens  20  results in a directed beam of light rays being transmitted through the lens  20 . In the embodiment of FIGS. 1 and 2, the waveguide  12  has a solid circular cross-sectional shape, which acts to focus and collimate a portion of the scattered light rays R which are directed and transmitted through the lens  20  to provide an intense, directed beam of light into the interior  54  of the vehicle  56  as illustrated diagrammatically in FIG.  2 . 
     FIGS. 3 and 4 show alternative waveguide cross-sectional shapes wherein the same reference numerals used in connection with the waveguide  12  are employed but are offset by increments of 100 and 200, respectively, to indicated like parts. Each of the waveguides  112 ,  212  of FIGS. 3 and 4 have curved lens configurations which act to focus and collimate some of the scattered light rays into a directed beam R for transmission through the support frame lens  20 . The waveguide  112  of FIG. 3 has a parabolic cross-sectional shape which would serve to intensify the focusing the collimation of the scattered light rays to produce a high intensity beam of light R. The waveguide  212  illustrated in FIG. 4 has a flat, planar back side surface  242  on which the roughened region  252  is formed, causing light to be scattered in a nondirected manner. However, the opposite side of the waveguide adjacent the lens  20  has an exterior concave profile which would act to align and collimate some of the scattered light rays to provide an intense beam of light R transmitted through the lens  20 . 
     FIG. 5 illustrates still a further embodiment  312  of the waveguide having a rectangular profile wherein the same reference numerals are employed for like features, but offset by 300. Such may be used in conjunction with a curved frame lens  20  having light-focusing characteristics for generating a similar directed beam of light into the interior  54  of the vehicle  56 . 
     Some of the light entering the waveguide  12  through the light input end  14  will reach the opposite end  16  without having been transmitted through the lens  20 . The end  16  may be capped off with reflective silver tape or the like so as to redirect the light back through the waveguide  12  toward the input end  14  to intensify the emission of light through the lens  20 . Alternatively, the opposite end  16  may be coupled with a waveguide or fiber(s) of another DLS to serve as a light input source thereto. 
     As the light travels along the waveguide  12 , it may have a tendency to lose some of its intensity as it nears the opposite end  16  relative to the intensity of the light adjacent the input end  14 . To counteract such a problem, a waveguide  412  having an alternative construction is illustrated in FIG. 6 wherein again like reference numerals have been used to represent like features, but offset by 400. The roughened region  452  of the waveguide  412  is tapered so as to be wider adjacent the opposite end  416  and gradually narrowing toward the input end  414 . This provides a relatively greater amount of light scattering adjacent the opposite end  416  to compensate for the reduced intensity there resulting from light lost laterally out of the waveguide  412  along its length. 
     FIG. 7 shows still another alternative embodiment of the waveguide  512  (corresponding reference numerals used, offset by 500) which is generally like that illustrated in and described in FIGS. 1 and 2 except for provision of integrated mounting features for securing the waveguide  512  to the support frame  18 , which may take the form of compatible screw mount portions  60  that align and cooperate with the screw mount portions  38  of the frame  18  for accepting the screws  36  to join the waveguide  512  to the frame  18 . With this embodiment of the waveguide  512 , the fastened cover  40  may be omitted and, if desired, reflective tape  70  may be applied to the exposed back side portion  542  of the waveguide  512  for reflecting any scattered light that would otherwise escape through the back side portion  542  back into the waveguide  512 . Beneath the tape  70  or incorporated into the inner surface of the tape  70  is a light-scattering region  552  as described previously. 
     The invention thus contemplates a DLS having a waveguide mounted in a support frame formed with a protective light-transmitting lens portion opposite a light-scattering region of the waveguide which is operative to scatter light introduced into the waveguide causing some of the light to be transmitted out of the waveguide through the lens. 
     It is further contemplated that such a DLS be mounted in an interior trim panel of an automotive vehicle, such as a headliner, door panel, instrument panel, seal panel, etc., with the lens of the frame accommodated in an opening of the panel and the remaining portions of the frame and components of the DLS concealed behind the panel. 
     The invention further contemplates waveguides having a number of different cross-sectional shapes with at least some of which having a concave exterior profile acting in conjunction with the light-scattering region to focus and collimate some of the scattered light rays that are directed toward the lens of the support frame to provide a high intensity light beam into the interior of a vehicle. 
     It will thus be apparent that there has been provided in accordance with the present invention a waveguide assembly which achieves the aims and advantages specified herein. It will of course be understood that the foregoing description is of preferred exemplary embodiments of the invention and that the invention is not limited to the specific embodiments shown. Various changes and modifications will become apparent to those skilled in the art and all such variations and modifications are intended to come within the scope of the appended claims.