Abstract:
A light guide assembly includes a base and a light source that are removably secured to the base. The light source is oriented to emit light out and away from the base. A light distributor is spaced apart from the light source and distributes the light across the light guide assembly. The light distributor includes a primary reflection surface with a plurality of transmission elements extending out from the primary reflection surface therealong to allow a portion of the light to pass through the transmission elements of the primary reflection surface without being reflected by the primary reflection surface. This facilitates the creation of a uniform beam of light being emitted by the light guide assembly.

Description:
BACKGROUND ART 
   1. Field of the Invention 
   The invention relates to a light guide assembly. More particularly, the invention relates to a light guide assembly that disperses light in a uniform manner across an entire lens through which light is emitted. 
   2. Description of the Related Art 
   Light guide or emitting devices are known. EP 0 780 265 B1 discloses a light-emitting unit. To the observer of the light guide device described in this disclosure, the central area of the light guide device appears dark. 
   SUMMARY OF THE INVENTION 
   A light guide assembly includes a base and a light source removably secured to the base. The light source is oriented to emit light out and away from the base. The light guide assembly also includes a light distributor spaced apart from said light source for distributing the light across the light guide assembly. The light distributor includes a primary reflection surface with a plurality of transmission elements extending out from the primary reflection surface therealong to allow a portion of the light to pass through the transmission elements of the primary reflection surface without being reflected by the primary reflection surface. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Advantages of the invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
       FIG. 1  is a cross-sectional side view of one embodiment of the invention with a light source emitting light; 
       FIG. 2  is a perspective view of a the invention with the surface light guide removed; 
       FIG. 3  is a perspective view of a collimator incorporated into the invention; 
       FIG. 4  is a fragmentary side view of a the light distributor with light graphically represented by arrows; 
       FIG. 5  is a fragmentary side view of an alternative embodiment of the light distributor with light graphically represented by arrows; 
       FIG. 6  is a fragmentary side view of a plurality of light deflecting surfaces with light graphically represented by arrows; 
       FIG. 7  is a fragmentary side view of an alternative embodiment of a plurality of light deflecting surfaces with light graphically represented by arrows; 
       FIG. 8  is a detailed side view of optical deflection structures; 
       FIG. 9  is a side view of a light guide assembly unit with a surface light guide; 
       FIG. 10  is a rear view of a light guide assembly according to  FIG. 9 ; 
       FIG. 11  is a perspective view of the invention unit with deflection structures according to  FIG. 8 ; and 
       FIG. 12  is a perspective view of an alternative embodiment of the invention having with three light guide assembly units. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  shows a section through a light guide assembly or light-emitting unit  5  with a light source  10  and with two light distributors  30 ;  50 . This light guide assembly  5  is, for example, a part of a motor vehicle&#39;s combined rear light unit not represented in more detail in this Figure. In  FIG. 2 , this light guide assembly  5  is represented in a perspective view. And, in  FIG. 3 , a perspective view of the collimator  113  surrounding the light source  10  of this light guide assembly  5  is represented. 
   The light source  10  is, for example, a light-emitting diode or luminescence diode  10 . It includes a light-emitting chip  11  with electrical connections  12  and a light-deflecting element  13 . The light-deflecting element  13  is, for example, a transparent, light-refracting element. The material of the light-deflecting element  13  is, for example, a thermoplastic plastic, e.g. PMMA, PMMI, etc., or glass. The light-deflecting element  13  consists, for example, of a base  14  and of a parabolic shell  15  at whose focal point, for example, the light-emitting chip  11  is located. The parabolic shell  15  has a plane, circular light exit surface  19  which is normal to the optical axis  22  of the light source  10 . The circular light exit surface  19  encircles a second light exit surface  16  set lower in the parabolic shell  15 . This is, for example, a converging, optical lens  16 . It can, for example, be embodied as a Fresnel lens. Around the optical lens  16  there is a chamfer  21 . The distance from the base plane  17  of the optical lens  16  to the light-emitting chip  11  is greater than the focal length of the optical lens  16 . This distance corresponds approximately to one half of the length of the light-deflecting element  13  between the light-emitting chip  11  and the light exit surface  19  of the light-emitting diode  10 . In this embodiment, the outer diameter of the light exit surface  19 , e.g. 9 mm, is twice as large as the outer diameter of the chamfer  21 . 
   The two light distributors  30 ;  50  are elements which are disposed so as to be axially symmetric to the optical axis  22  of the light source  10  and each of whose cross section represented in  FIG. 1  has at least approximately the form of a trapezoid. The two light distributors  30 ;  50  each have a light entry surface  31 ;  51  and a light exit surface  32 ;  52 . Here the surfaces  31 ,  32 ;  51 ,  52  are parallel to one another. They are furthermore parallel to the light exit surface  19  of the light source  10 . With respect to the light entry surfaces  31 ;  51 , the light exit surfaces  32 ;  52  are each offset from the optical axis  22  toward the outside by approximately 25% of the length of the individual light distributor  30 ;  50 . The length of the light entry surfaces  31 ;  51  of the individual light distributor  30 ;  50  in the representation of  FIG. 1  in the direction transverse to the optical axis  22  is in the embodiment example approximately 28% of the length of this light distributor  30 ;  50  and the length of the light exit surfaces  32 ;  52  is approximately 75%. In this embodiment, the sum of the lengths of both light distributors  30 ;  50  is 35 mm. The height of the light distributor  30 ;  50  in the representation of  FIGS. 1 and 2  is 26% of the length of this element  30 ;  50 . The two side faces  33 ,  34 ;  53 ,  54  of each of the light distributors  30 ;  50  are parallel to one another. 
   The light distributors  30 ;  50  have face-side surfaces  35 ,  36 ;  55 ,  56  which lie opposite one another, are not parallel, have different lengths in the sectional representation of  FIG. 1 , and are composed of individual surface elements  37 - 39 ,  40 - 42 ;  57 - 59 ,  60 - 62 . The respective short face-side surface  35 ;  55  consist of five oblique surface elements  37 ;  57 . Disposed between those elements are an additional four surface elements  38 ;  58  as well as end flank surface elements  39 ;  59 , which border the surface elements  38 ;  58 . The surface elements  37 ;  57  and the light entry surface  31  are at a wedge angle of 45° to one another. The individual surface elements  37 ;  57  are equally large and lie in a common plane. 
   The surface elements  38 ;  58  border, for example, the respective surface element  37 ;  57  lying above in  FIG. 1 . These surface elements  38 ;  58  lie parallel to the light entry surface  31 ;  51 . The individual surface elements  38 ;  58  are equally long. Their length is 1.4% of the length of the light distributor  30 ;  50 . In an imaginary projection onto the light entry surfaces  31 ;  51 , each two adjacent surface elements  38 ;  58  are at a distance from one another of, for example, 5.8% of the length of a light distributor  30 ;  50 . 
   In the representation of  FIG. 1 , the surface elements  38 ;  58  project out from the face-side surfaces  35 ;  55 . An end flank surface element  39 ;  59 , which is normal to the surface element  38 ;  58 , connects a surface element  38 ;  58  to an oblique surface element  37 ;  57  lying below. 
   In  FIGS. 4 and 5 , two additional embodiment variants of the face-side surfaces  35  of a light distributor  30  are shown. In  FIG. 4 , the surface elements  238  are longer by 10% than the surface elements  38  represented in  FIG. 1 . The end flank surface elements  239  and the surface elements  238  are the boundaries of an acutely angled wedge. 
     FIG. 5  shows surface elements  338  which are impressed in the light distributor  30 . These surface elements  338  also lie parallel to the light entry surface, not represented here, of the light distributor  30 . Here, the end flank surface elements  339  each connect a surface element  338  to an oblique surface element  37  disposed above in the representation of  FIG. 5 . 
   The long face-side surfaces  36 ;  56  of the light distributor  30 ;  50  each consist of  25  disposed surface elements  40 - 42 ;  60 - 62  ( FIGS. 1 and 2 ). One half  40 ,  41 ;  60 ,  61  of these surface elements  40 - 42 ;  60 - 62  are, for example, disposed in such a manner that they form a series of steps parallel to the oblique surface elements  37 ;  57  of the short face-side surfaces  35 ;  55 . These surface elements  40 ,  41 ;  60 ,  61  are denoted in the following as step surface elements  40 ,  41 ;  60 ,  61 . The other surface elements  42 ;  62 , also disposed in such a manner that they form a series of steps, are end flank surface elements and connect the surface elements  40 ,  41 ;  60 ,  61  to one another. The end flank surface elements  42 ;  62  are each at an angle with a step surface element  40 ,  41 ;  60 ,  61  which borders it on an apical line  44 ;  64 , said angle being, for example, less than 135°. 
   In an imaginary projection onto the plane of the light entry surfaces  31 ;  51  each two adjacent apical lines  44 ;  64  are, for example, at the same distance to one another. 
   In the light distributors  30 ;  50  represented in  FIGS. 1 and 2 , the step surface elements  40 ,  41 ;  60 ,  61  are of two different sizes. Thus, in  FIG. 1 , as measured from the light entry surface  31 ;  51 , the fourth, the seventh, the tenth, and the thirteenth step surfaces  41 ;  61  are larger by 50% than the other step surfaces  40 ;  60 . Each imaginary line parallel to the light entry surface  31 ;  51  in the longitudinal direction of the light distributor  30 ;  50  through an end flank surface element  39 ;  59  of the short face-side surface  35  intersects, in the embodiment example of  FIG. 1 , a large step surface element  41 ;  61  of the long face-side surface  36 . 
   In  FIGS. 6 and 7 , additional embodiments of a long face-side surface  36  are represented. The number and the angular position of the step surface elements  240 ,  241 ;  340 ,  341  are identical to those in the embodiment shown in  FIGS. 1 and 2 . In  FIG. 6 , the distance to the apical lines  244 ,  245  projected onto the plane of the light entry surface  31  is not constant. The apical lines  244  bound the small step surface elements  240 . The apical lines  245  lie on the large step surface elements  241 . In this embodiment, the large step surface elements  241  are larger by 87% than the small step surface elements  240 . 
   Also, the light distributor  30  represented in  FIG. 7  has step surfaces  340 ,  341  of a different size. The large step surface elements  341  are 80% larger than the small step surface elements  340 . All the apical lines  344  which bound a large step surface element  341  are in a projection onto the plan of the light entry surface  31  at the same distance from both adjacent apical lines  344  bordering a large step surface element  341 . 
   The individual light distributor  30 ;  50  can comprise combinations of the embodiments described. Thus, it can, for example, have a short face-side surface  35 ;  55  according to  FIG. 4  and a long face-side surface  36 ;  56  according to  FIG. 7 . Also, the face-side surfaces  35 ,  36 ;  55 ,  56  can have configurations differing by section. 
   The distance of the two light distributors  30 ;  50  from one another, the length of the seam  49 , corresponds to the length of one of the surface elements  38 ;  58  represented in  FIG. 1 . The two light distributors  30 ;  50  can also be connected to one another, for example, by means of a central bar of constant thickness. Instead of two light distributors  30 ;  50  a single rotationally symmetric light distributor can also be used. The axis of rotation is in this case, for example, the optical axis  22  of the light source  10 . 
   During the operation of the light guide assembly  5 , light  101 - 108  from the light-emitting chip  11  is produced in the light source  10 . A part of the light  101 - 108  emitted by the light-emitting chip  11  and represented in  FIG. 1  as a dotted line strikes the boundary surface of the light-deflecting element  13 , which is formed by the converging lens  16 . The angle between the striking light and a normal at the point of incidence is less than the critical angle of total reflection. This critical angle is, in PMMA for example, 42°. The striking light passes through the converging lens, where it is refracted in the direction of the optical axis  22 . The light exiting from the converging lens  16  is parallel to the optical axis  22  of the light guide assembly  5 . 
   The part of the light  101 - 108  emitted by the light-emitting chip  11  which does not pass through the converging lens  16 , strikes the boundary surface of the light-deflecting element  13  which is formed by the circumferential surface of the parabolic shell  15 . The angle at which it strikes is greater than the critical angle of total reflection. This part of the light bundle  101 - 108  is completely reflected in the direction of the light exit surface  19 . It passes through the light exit surface  19  in the normal direction and is also parallel to the optical axis  22  of the light source  10 . The light-deflecting element  13  of the light source  10  collimates the light  101 - 108  emitted by the light-emitting chip  11 . It thus acts as collimator  113  for the light  101 - 108 . The direction  9  of the collimated light  101 - 108  emitted by the light source  10  is parallel to the optical axis  22  of the light source  10 . 
   The collimated light  101 - 108  passes through the light entry surfaces  31 ;  51  into the light distributors  30 ;  50 . In the light distributors  30 ;  50 , it strikes the boundary surfaces which are formed by the short face sides  35 ;  55 . These two boundary surfaces form a beam splitter  135  for the light bundle  101 - 108 . 
   The light bundle  101 - 108  strikes the beam splitter  135  in the sections in which the surface elements  38 ;  58  represented in horizontal position in  FIG. 1  are the boundaries of the respective light distributor  30 ;  50  as well as at the seam  49  between the light distributors  30 ;  50  and in the sections in which the surface elements  38 ;  58  which are oblique in this Figure form the boundary of the element. The light  104 ,  108  which strikes normal to the boundary surface in the sections  38 ;  58  represented in horizontal position passes through these boundary surfaces into the environment  1 . The areas of these boundary surfaces illuminated by the light source  10  are light passage surfaces  138 . These light passage surfaces  138  lie at least approximately normal to the direction  9  of the parallelized light  101 - 108 . Also the seam  49  forms a light passage surface  138  through which the light bundle  101  exits into the environment  1 . All the light passage surfaces  138  are, in a projection opposite the direction of the parallelized light  101 - 108 , of the same size and in each case are at the same distance from two adjacent light passage surfaces  138 . 
   Light bundles  102 ,  103 ,  105 - 107  which strike boundary surfaces formed by the oblique surface elements  37 ;  57  strike here at an angle to the normal to the boundary surface, said angle being greater than the critical angle of total reflection of the material of the respective light distributor  30 ;  50  against the ambient air  1 . These boundary surfaces form the light-reflecting surfaces  137  at which the striking light  102 ,  103 ,  105 - 107  is deflected, for example, completely in the longitudinal direction of the respective light distributor  30 ;  50 . After the reflection the light bundles  102 ,  103 ,  105 - 107  are once again parallel to one another. Between the light bundles  102 ,  103 ,  105 - 107  there are non-illuminated gaps  111  since the light  101 ,  104 ,  108  passing through the light passage surfaces  138  is not deflected. Boundary surfaces of the light distributors  30 ;  50 , specifically those formed by the end flank surface elements  39 , are not illuminated. 
   If the light distributor  30 ;  50  is structured as in  FIGS. 4 and 5 , the light  101 - 108  emitted by the light source  10  is split at the beam splitter section  135  shown in these Figures in a manner at least similar to that in the case of the beam splitter  135  represented in  FIG. 1 . In each of  FIGS. 4 and 5 , only the central area of the parallelized light bundles  103 - 108  tangential to one another is represented for the purposes of illustration. In an embodiment according to  FIG. 4 , the light  104 ,  108  passing through the light passage surfaces  138  is, due to the end flank surfaces  239 , for example, not reflected or refracted. In the embodiment example according to  FIG. 4 , the light passage surfaces  138  are only the areas of the boundary surfaces formed by the surface elements  238  and illuminated by the light source  10 . 
   The light bundles  102 ,  103 ,  105 - 107  deflected at the beam splitter  135  strike the boundary surfaces of the respective light distributor  30 ;  50 , where said boundary surfaces are disposed in such a manner that they form a series of steps and are formed by the step surface elements  40 ,  41 , ( FIG. 1 ). Here these boundary surfaces are only partially illuminated. The illuminated areas are light-deflecting surfaces  142 ,  143 ,  145 - 147  of a light-deflecting area  140  at which the light bundles  102 ,  103 ,  105 - 107  are reflected in the direction of the light exit surface  32 ;  52 . In this case, the light bundle  102  strikes, for example, the light-deflecting surface  142 , the light bundle  103  strikes the light-deflecting surface  143 , and the light bundle  105  strikes the light-deflecting surface  145 . The latter is, for example, part of a boundary surface formed by a large step surface element  41 ;  61 . The light bundle  103 , which, for example, lies above the light bundle  102  in the representation of  FIG. 1 , is tangential to the light-deflecting surface  142  and strikes the light-deflecting surface  143  next further removed from the beam splitter  135 . In a projection opposite to the direction of the portions of light  102 ,  103 ,  105 - 107  deflected at the light-deflecting surfaces  142 ,  143 ,  145 - 147  the distance of the light-deflecting surfaces  142 ,  143 ,  145 - 147  from one another is the same. In this projection this distance also corresponds to the distance of the light passage surfaces  138  from one another and from the light-deflecting surfaces  142 ,  143 ,  145 - 147 . The surfaces  138 ,  142 ,  143 ,  145 - 147  are in the projection, for example, of the same size. The boundary surfaces formed by the end flank surface elements  42 ;  62  do not affect the light  102 ,  103 ,  105 - 107 . There is, for example, no reflection or refraction of the light bundles  102 ,  103 ,  105 - 107 . The light bundles  101 - 108  which pass through the beam splitter  135 , are deflected in the deflection area  140 , and exit at the light exit face  32 ;  52  are at the same distance from one another and have the same cross section. They have in this embodiment example the same direction  9  as the light  101 - 108  emitted by the light source  10 . The gaps  111  do not appear and are not visible to the observer. The light exiting from that in  FIGS. 1 and 2  is equally divided over the surface. On observation from a suitable distance the impression of a uniformly distributed luminance is produced. 
   In an alternative embodiment of the light distributors  30 ;  50  according to one of the  FIG. 6  or  7 , the gap  111  is also bridged in the light-deflecting area  140  so that a uniform luminance distribution results. In an embodiment according to  FIG. 6 , for example, the light-deflecting area  143  is formed by a large step surface element  241  while the light-deflecting surfaces  142 ,  145 - 147  are formed by small step surface elements  240 . Whereas in  FIG. 7 , all the light-deflecting surfaces  142 ,  143 ,  145 - 147  are parts of the boundary surfaces which are formed by large step surface elements  341 . 
   The size of the light-deflecting surfaces  142 ,  143 ,  145 - 147  may increase with increasing distance from the beam splitter  135 . Some midlines of the light-deflecting surfaces  142 ,  143 ,  145 - 147 , specifically those projected opposite to the direction of the light  101 - 108  exiting from the light exit surfaces  32 ;  52 , are then at the same distance from one another. In large light distributors  30 ;  50 , it is thus possible to compensate the attenuation of the light intensity due to material absorption so that light emission from the light guide assembly  5  will appear substantially uniform across the entire light exit surface  73 . 
   The light-deflecting surfaces  142 ,  143 ,  145 - 147  thus projected and the light passage surfaces  138  can also be of different sizes. Thus, e.g. in a light-emitting diode  10 , areas of different light intensity can be equalized. For example, areas of greater light intensity can illuminate small light-deflecting surfaces  142 ,  143 ,  145 - 147  and light passage surfaces  138  while areas of low light intensity illuminate large surfaces  138 ,  142 ,  143 ,  145 - 147 . 
   The beam splitter  135  and the light-deflecting surfaces  142 ,  143 ,  145 - 147  can be parts of different elements. For example, the light-reflecting surfaces  137  of the beam splitter  135  around the light-deflecting surfaces  142 ,  143 ,  145 - 147  can be mirror surfaces of individual mirrors, which may or may not be adjustable. 
     FIGS. 9 and 10  show a front view and a side view of the light guide assembly  5  with a surface light guide, generally shown at  70 . The light source  10  and the light distributor  30 ;  50  described in  FIGS. 1 and 2  are used as components thereof. 
   The surface light guide  70  represented in  FIGS. 9 and 10  has the structure of a regular three-sided prism having a base surface  71  and a top surface that are parallel and congruent right-angled triangles. It may be a transparent plastic element similar to or of the same material as the light-deflecting element  13  and/or the light distributor  30 ;  50 . A lower side  72  of the surface light guide  70  is, for example, a right-angled plane surface, which lies directly on and covers the light exit surfaces  32 ;  52  of the light distributor  30 ;  50 . 
   Perpendicular to this surface  72  and embodied in these Figures as a plane surface, is a front side surface, generally shown at  73 , of the surface light guide  70 . The height of the front side surface  73  of the surface light guide  70 , here shown shortened, is, for example, 80% larger than its length parallel to the light distributors  30 ;  50 . The front side surface  73 , which is the light exit surface  73  of the surface light guide  70 , is in this embodiment example 25 times as large as the total of the light exit surfaces  16 ,  19  of the light source  10 . The light exit surface  73  can also be more than 200 times as large as the total of the light exit surfaces  16 ,  19 . 
   A rear side surface  74  of the surface light guide  70  has horizontal triangular notches  75 . The length of the individual notches  75  is equal to the length of the surface light guide  70 . These notches  75  are disposed in such a manner that they form a series of steps at a constant distance from one another. The distance between the individual notches  75  is, for example, twice as large as the width of the individual notches  75 . In the embodiment shown, the width of the notches is between 0.5 mm and 1 mm. The two notch surfaces  76 ,  77  are, in the representation of  FIGS. 9 and 10 , plane surfaces. A normal  76   a  to the lower notch surface  76  makes with an imaginary line which is generally parallel to the lower side  72 , for example, an angle which is greater than or equal to the critical angle of total reflection for the material of the surface light guide  70  against air  1 . 
   On the rear side  78  of the surface light guide  70  an additional light source, not represented here, can be disposed. The direction of the light emitted by this light source is then, for example, at least approximately normal to the light exit surface  73  of the surface light guide  70 . 
   During the operation of the light guide assembly  5  the light  101 - 108  emitted by the light source  10  is divided in the light distributors  30 ;  50  as described in connection with  FIGS. 1-7 . In the individual light bundles  101 - 108  parallel to one another, the luminous flux is largely equal. 
   The light bundles  101 - 108  enter into the surface light guide  70  through its lower side  72 . In the surface light guide  70 , the light bundles  101 - 108  strike boundary surfaces which are formed by the notch surfaces  76 . In  FIGS. 9 and 10 , for example, two possible light paths  171 ,  172  are represented. These light paths  171 ,  172 , which are each partial light bundles of the light bundles  101 - 108 , each illuminate a part of the boundary surface formed by the notch surfaces  76 . The illuminated surfaces are light-reflecting surfaces  176 - 178 . The part of the luminous flux  101 - 108  which, for example, is tangential to the light-reflecting surface  176 , therefore in the representation in  FIG. 9  passing by to the right of the light-reflecting surface  176 , strikes the next further removed light-reflecting surface  177 . 
   The partial luminous fluxes  171 - 172  striking these light-reflecting surfaces  176 - 178  are, for example, completely deflected in the direction of the front side  73  and pass through this light exit surface  73  into the environment  1 . An observer sees from, a distance of approximately two to three meters, the homogeneously shining front side  73  of the surface light guide  70  with a uniform luminance distribution. 
   If in addition the light source disposed on the rear side  78  of the surface light guide  70  is switched on, the light emitted by this light source penetrates the surface light guide  70  substantially unhindered. The observer can recognize this additional light source clearly. Depending on the luminance of the light source  10  and the additional light source, either the total luminance is increased or only one light source is perceived when they are operating simultaneously. In other alternative embodiments, several light sources can also be disposed on the rear side  78  of the surface light guide  70 . 
   The surface light guide  70  can be arched. Thus, the front side  73  of the surface light guide  70  can form, for example, the outer contour of a vehicle. Also, the light distributors  30 ;  50  of a light guide assembly  5  of this type can have a structure adapted to a vehicle contour. 
     FIG. 11  shows a light guide assembly  5  with a surface light guide  70  whose reflecting surfaces  176 - 178  comprise optical structures  81 . These optical structures  81  are, for example, a plurality of ellipsoidal extracts  82  arched toward the environment  1 . 
   Referring to  FIG. 8 , an extract of these optical structures  81  is observed from the lower side  72  of a transparent surface light guide  70 . The longitudinal axis of the individual imaginary ellipsoids is in this case parallel to the lower side  72  and parallel to the front side  73  of the surface light guide  70 . Here the reflecting surfaces  176 - 178  disposed one behind another for the striking light bundles  101 - 108  are represented one above another. The ellipsoidal extracts  82  disposed on the individual reflecting surfaces  176 - 178  are disposed so as to be offset with respect to one another. 
   The light bundles  101 - 108  striking the reflecting surfaces  176 - 178  are reflected on the optical structures  81 . The reflected light is distributed in space so that a solid-angle field of ±20° in the horizontal direction and ±10° in the vertical direction is illuminated. 
   In  FIG. 12 , an arrangement of three light guide assemblies  5  is represented. They are disposed next to one another where the face surfaces of the surface light guide  70  border one another. With this arrangement, a large-surface illumination can be produced. It should be appreciated by those skilled in the art that one light source or several light sources can be disposed on the rear side  78  of the surface light guide  70 . 
   The light-emitting units  5  represented in  FIGS. 1 ,  2 , and  9  through  12  can be embodied as a single part. Thus, the entire light guide assembly  5  can form one injection-molded part into which the light source  10  is formed or onto which the light source  10  is formed. The light source  10 , which can, in addition to a light-emitting diode, be an incandescent lamp, a halogen lamp, and the like, can also be clipped onto the light distributor(s)  30 ;  50  or connected to it in some other manner. 
   The optical element  113  which collimates the light  101 - 108  emitted by the light source  10  can also be part of a light distributor, or the light distributors,  30 ;  50 . The light  101 - 108  striking the light distributor  135  can, for example, also be collimated by means of an optical lens, an, e.g. parabolic, reflector, and so on. 
   With the light source  10  switched off, the light guide assembly  5  appears clearly and unstructured. If the light source  10  is switched on, a uniformly shining surface without faults appears to the position of the observer. 
   The light guide assembly  5  is compactly structured and can thus, for example, be used as part of a combined rear light unit in a motor vehicle. For example, it can comprise a tail light with blinkers and/or brake light disposed behind it. 
   The invention has been described in an illustrative manner. It is to be understood that the terminology, which has been used, is intended to be in the nature of words of description rather than of limitation. 
   Many modifications and variations of the invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the invention may be practiced other than as specifically described.