Abstract:
A light assembly disperses light emitted by a light source. The lighting assembly includes a light entry surface for receiving the light emitted by the light source. A direction surface directs the light in a predetermined direction. A stepped region, disposed adjacent the light entry surface receives the light directed by the direction surface and reflects the light. The stepped region includes a plurality of step parts, each defining a light deflection surface, wherein each of the light deflection surfaces is greater in area s step distance between the light deflection surface and the direction surface increases.

Description:
FIELD OF THE INVENTION 
   The invention relates to a lighting assembly with at least one light source and at least one optical waveguide element. More particularly, the invention relates to a lighting assembly having an optical waveguide element, optically connected after the light source, with light deflection surfaces arranged staggered and directly or indirectly illuminated by the light source. 
   DESCRIPTION OF THE RELATED ART 
   A known lighting assembly is disclosed in European patent EP 1 167 869 A2. The optical waveguide element is a wedge-like component, whose point faces away from the light source. The two wedge surfaces, one of which is a reflection surface and the other a light outlet surface, have a regular structure. The light outlet surface has additional optics, in order to achieve the desired optical impression. The configuration of the light outlet surface is therefore dependent on the desired optical effect. 
   The problem with this configuration is the inability to generate a homogeneously distributed output light, whose light output surface can be configured, for the most part, freely. 
   SUMMARY OF THE INVENTION 
   A light assembly disperses light emitted by a light source. The lighting assembly includes a light entry surface for receiving the light emitted by the light source. A direction surface directs the light in a predetermined direction. A stepped region, disposed adjacent the light entry surface receives the light directed by the direction surface and reflects the light. The stepped region includes a plurality of step parts, each defining a light deflection surface having a length equal to the length of each of the other of the light deflection surfaces, wherein each of the light deflection surfaces is greater in area as step distance between the light deflection surface and the direction surface increases. 

   
     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 perspective view of one embodiment of the invention; 
       FIG. 2  is a top view, partially cut away, a the invention according to  FIG. 1  with a light source secured thereto; 
       FIG. 3  is a side view of the invention according to  FIG. 1 ; 
       FIG. 4  is an enlargement of the step region of the invention with light represented as passing therethrough; and 
       FIG. 5  is an enlarged top view, partially cut away, of a deflection-reflector used in the invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 2  shows the top view of a lighting assembly  2 , for example, a rear lamp of a vehicle. The lighting assembly  2  includes a light source  6  and an optical waveguide element  10  optically connected with the light source  6 . The light source  6 , which may be a light-emitting diode, an incandescent lamp, a halogen lamp, and the like, can be mounted on the optical waveguide element  10 , molded into it, clipped in, etc.  FIGS. 1 and 3  show the optical waveguide element  10  with the light source  6 .  FIG. 1  shows a perspective view of a back side  11  and  FIG. 3  represents a side view of the optical waveguide element  10 . The lighting assembly  2  can be designed in one or several parts. 
   With the lighting assembly  2  incorporated in a vehicle (not shown here), the light source  6  is situated, for example, within the vehicle on the back side  11  of the optical waveguide element  10 . From outside of the vehicle, for example, two light outlet surfaces  71 ,  91  of the lighting assembly  2  are visible, which delimit the vehicle contour. These light outlet surfaces  71 ,  91  are arranged on the front  12  of the optical waveguide element  10 . 
   The lighting assembly  2  is axi-symmetric about a horizontal central longitudinal plane and a vertical central transverse plane through the light source  6 , respectively. These two above-mentioned planes intersect in an imaginary line through the light source  6  oriented in the direction of radiation  9 . 
   The optical waveguide element  10 , for example, is a one-piece, transparent plastic element, for example, made of PMMA, modified PMMI, etc. It consists of a light distributor  21 , an upper light outlet unit  61  and a lower light outlet unit  81 . Its length, in the practical example depicted in  FIGS. 1-3 , is four times its depth and 2.4 times its height. 
   The light distributor  21  is a crescent-shaped component and defines a curved path. In the practical example, it is precisely as long as the optical waveguide element  10 . Its depth is about 11% of its length, its height about 6% of the length. A light entry surface  23  lies in the rear outside surface  22 , symmetric to the vertical central transverse plane. This is a quadratic flat surface, whose edge length corresponds to the height of the light distributor  21 . 
   On both sides of light entry surface  23 , the outer surface  22  consists of a stepped region  31 ;  41 , which connects the light entry surface  23  to the corresponding face  13 ,  14 . 
   The individual steps  32 ,  33 ;  42 ,  43  of the stepped region  31 ;  41  consist of step surfaces  32 ;  42  and rear surfaces  33 ;  43  adjacent to them. Each of the plurality of step surfaces  32 ,  42  define a step distance as that distance between each step surface  32 ,  42  and the light entry surface  23 . The step surfaces  32 ,  42  are interfaces of the light distributor  21  relative to the surroundings  1 . The individual step surfaces  32 ;  42  lie roughly parallel to each other and are normal to the horizontal central longitudinal plane of the lighting assembly. They form an angle of 45 degrees, for example, with the vertical central transverse plane. The step surfaces  32 ;  42  can also form a different angle with these planes. 
   Each step surface  32 ;  42  and one of the two rear surfaces  33 ;  43  adjacent to it form an angle of ninety degrees with each other in the depiction of  FIG. 2 . This enclosed angle can also be more acute or more obtuse. The crest level  34 ;  44 , which is shown as a vertex in the top view of  FIG. 2 , is the crest line of a concave notch. 
   The distance of the individual crest levels  34 ;  44  relative to each other is not constant within the corresponding step regions  31 ;  41 . The distance of any crest level  34 ;  44  to a crest level  35 ;  45  that is farther away from the light entry surface  23 , is smaller than the distance to a crest level  36 ;  46  that lies closer to the light entry surface  23 . The distance of two adjacent crest levels  34 ,  35 ;  34 ,  36 ;  44 ,  45 ;  44 ,  46  is smaller, the farther these crest levels  34 ,  35 ;  34 ,  36 ;  44 ,  45 ;  44 ,  46  are from the light entry surface  23 . 
   The light distributor  21  has a recess  25  with a square cross-section, which is symmetric to the vertical central transverse plane. The length of the short diagonals of the recess  25 , for example, is 44%, the length of the long diagonals 80% of the depth of the light distributor  21 . The distance of this recess  25  from the light entry surface  23 , for example, is one-fifth of the depth of the light distributor  21 . The cross-section of the recess  25  can taper, for example, in the direction of the horizontal central longitudinal plane. 
   The boundary surfaces  26 ,  27  of recess  25  lying closer to the light entry surface  23  may be sections or portions of the surfaces of a cylinder, an ellipsoid, a paraboloid, a cone, and the like. If the boundary surfaces  26 ,  27  are sections of a cylinder or cone surface, the base surface of the cylinder or cone can be circular, elliptical, oval, etc. The base surface can also be bounded by an arbitrarily curved, continuous or non-continuous three-dimensional curve, for example, by a parabola. It is also conceivable to make these boundary surfaces  26 ,  27  plane surfaces. 
   The boundary surfaces  28 ,  29  of recess  25  that are farther away from the light entry surface  23  can be plane surfaces, sections of surfaces of a cylinder, an ellipsoid, a paraboloid, a cone, etc. 
   The light distributor  21  has an at least roughly V-shaped notch  51  oriented in the longitudinal direction of optical waveguide element  10  on the front  12 , whose central plane coincides with the horizontal central longitudinal plane of lighting assembly  2 . The notch surfaces  52 ,  53  are the surface sections of a cylindrical surface, in which the cylinder has a base surface that is circular, elliptical, oval, etc., or is bounded by a closed, continuously or discontinuously curved three-dimensional curve. Optionally, the notch surfaces  52 ,  53  can also be flat surfaces or consist of individual continuous or discontinuously curved flat surface elements. The notch angle enclosed by the two notch surfaces  52 ,  53 , for example, is less than 100 degrees. 
   The two light output units  61 ,  81  are arranged symmetric to the horizontal central longitudinal plane of the lighting assembly  2 . Their length corresponds in the practical example to the length of the optical waveguide element  10 , their depth is about two-thirds the depth of the optical waveguide element  10 . 
   On the back  11 , each light output unit  61 ,  81  has a triangular longitudinal notch  63 ,  83  over its entire length, whose depth is roughly 20% of the depth of the optical waveguide element  10 . The crest lines  64 ,  84  of longitudinal notches  63 ,  83  lie here at one-third the height of the optical waveguide element  10 , offset to the horizontal central longitudinal plane. The notch angle of longitudinal notches  63 ,  83 , for example, is forty-six degrees. The boundary surfaces  65 ,  85  of longitudinal notches  63 ,  83  separated from the horizontal central longitudinal plane are flat surfaces that lie parallel to the horizontal central longitudinal plane. 
   The boundary surfaces  66 ,  86  of longitudinal notches  63 ,  83  lying closer to the horizontal central longitudinal plane consist of individual surface elements  67 ,  87 . These surface elements  67 ,  87  are surface sections of an outward arched cylinder, as shown in  FIGS. 1 and 5 . They lie parallel to each other, in which the axes of the cylinders are oriented across the longitudinal direction of the optical waveguide element  10  and their length corresponds to the width of the corresponding boundary surface  66 ,  86 . The surface elements  67 ,  87  can also be surface sections of ellipsoids, paraboloids, etc. They can be arched convexly or concavely. The axes of these surface elements can also lie obliquely to the longitudinal direction of optical waveguide element  10 . 
   The light outlet surfaces  71 ,  91  are sections of cylindrical surfaces. The corresponding cylinders, which lie parallel to the horizontal central longitudinal plane, have the length of the optical waveguide element  10  and an oval cross-section. They are offset by one-fourth the height of the optical waveguide element  10  relative to the horizontal central longitudinal plane. The height of the light outlet surfaces  71 ,  91 , for example, corresponds roughly to one-third the height of the optical waveguide element  10 . Optical lenses can be arranged on the light outlet surfaces  71 ,  91 . 
   For fastening in the vehicle, the optical waveguide element  10  has an upper  62  and a lower fastening flange  82 . These fastening flanges  62 ,  82  are parts of the upper  61  or lower light outlet unit  81 . 
   During production of the lighting assembly  2 , the optical waveguide element  10  is produced, for example, in an injection molding method. In this case, the light-emitting diode  6 , or parts thereof, can be molded therein. The optical waveguide element  10  becomes largely homogeneous because of this production method. Individual regions of the surface of the optical waveguide element  10  can be mirrored. 
   For incorporation in a vehicle, the lighting assembly  2 , for example, is fastened with the upper  62  and lower fastening flange  82  in the vehicle body and the light source  6  electrically connected. A diaphragm (not shown here) optionally lies between the light outlet surfaces  71 ,  91 . The incorporation dimensions of the lighting assembly  2  in the vehicle are essentially determined by the dimensions of the optical waveguide element  10 . The incorporation length of the lighting assembly  2  therefore corresponds to the length of the optical waveguide element  10  and the incorporation height corresponds to the height of the optical waveguide element  10 . The incorporation depth (see  FIG. 2 ) is determined by the depth of the optical waveguide element  10  and the light source  6 . 
   In a lighting assembly  2  that is switched off, the light outlet surfaces  71 ,  91  are visible from outside of the vehicle. They appear as uniform surfaces of homogeneous color. 
   During operation of the lighting assembly  2 , the light  101 - 109  emitted from light source  6  in radiation direction  9  passes through the light entry surface  23  into the light distributor  21  of optical waveguide element  10 . In the light distributor  21 , the light  101 - 109  impinges on the interfaces of recess  25 , which are formed by the boundary surfaces  26 ,  27 . These interfaces are light deflection and refraction surfaces  126 ,  127  for the impinging light  101 - 109 . 
   Light  101 , which impinges on the surfaces  126 ,  127  at an angle to the normal, which is smaller than the boundary angle of total reflection—in an optical waveguide element made of PMMA, this angle is forty-three degrees, for example—passes with refraction through the light deflection and refraction surface  126 ,  129  into recess  25 . Part of this light  101  (with refraction again) enters the optical waveguide element  10  through the boundary surfaces  28 ,  29 . 
   The light  102 - 109  that impinges at an angle on the light deflection and refraction surfaces  126 ,  127 , which is greater than the material-specific boundary angle, is reflected on these surfaces  126 ,  127 . 
   The two light deflection and refraction surfaces  126 ,  127 , arranged symmetric to each other, form a light divider  125 . When it impinges on the light divider  125 , the light  102 - 109  is deflected, both into the half of the light distributor  21  depicted on the top in  FIG. 2 , and into the half of the light divider  21  depicted on the bottom of the same figure. The reflected, diverging light  102 - 109  in  FIGS. 2 and 4  is shown as a parallel light bundle  102 - 109  for simplicity. 
   The two light reflectors  126 ,  127  of light divider  125  are indirect light sources for one-half of the light distributor  21 . The reflected light  102 - 109  in light distributor  21  is guided in the direction of the step surfaces  32 ,  42 , cf.  FIG. 4 . 
     FIG. 4  shows a detail of the light deflection region depicted in the upper half of  FIG. 2 . At the corresponding interfaces  32 ,  42 , only a section bordering the crest levels  34 ;  44  is illuminated. This corresponding section is a light deflection surface  132 - 139 . These light deflection surfaces  132 - 139  are arranged in a staggered manner, in which of the depicted light deflection surfaces  132 - 139 , the light deflection surface  132  having the smallest step distance has the smallest distance to light reflector  126  and the light deflection surface  139  having the largest step distance is farthest from the light reflector  126 . When the light source  6  is switched on, the part  102  of light  102 - 109  illuminates the light deflection surface  132 , the light part  103  illuminates the light deflection surface  133 , etc. The individual regions of light  102 - 109  lie right next to each other on leaving the light reflector  126 . The interfaces formed by the rear surfaces  33 ,  43  are free surfaces. 
   The farther the individual light deflection surfaces  132 - 139  are from light reflector  126 , the farther they extend into the light distributor  21  (rightward in  FIG. 4 . The amount by which a light deflection surface  133 - 139  lying away from light reflector  126  extends farther into light distributor  21  than the next closer light deflection surface  132 - 138  is not constant. This amount increases with distance of the light deflection surfaces  132 - 139  to light reflector  126 . Consequently, at least with roughly parallel light deflection surfaces  132 - 139 , the area of a light deflection surface  132 - 139  lying at greater distance is greater than the area of the next closer light deflection surface  132 - 139 . 
   The light  105  that illuminates the light deflection surface  135 , for example, is reflected rightward on this light deflection surface  135  in the depiction of  FIG. 4 . A light band  105  that is wider than the adjacent light band  104  is produced. The light intensity reflected on light deflection surface  135  is therefore greater than the light intensity deflected on light deflection surface  134 . At the same time, this light band  105  is narrower than the light band  106  that is reflected on light deflection surface  136 . A smaller light intensity is also deflected on the light deflection surface  135  than on the light deflection surface  136 . The partial light fluxes of the deflected light bundle are therefore at least roughly equal. 
   The light  107  that lies next to light part  106 , on leaving the light reflector  126  in the depiction of  FIGS. 2 and 4  on the right, is tangent to the light deflection surface  136  at its crest line  34  and illuminates the next farther light deflection surface  137 . The light part  106 , in turn, which illuminates the light deflection surface  136 , is tangent to the light deflection surface  135 . The entire reflected light  102 - 109  therefore impinges on light deflection surface  132 - 139 . 
   The light  102 - 109  impinging on the light deflection surfaces  132 - 139  has a different light intensity, among other things, because of absorption of the material. The farther distant light deflection surfaces  132 - 139  are thus illuminated with lower light intensity or illumination intensity than the closer lying light deflection surfaces  132 - 139 . 
   The center lines of the individual light deflection surfaces  132 - 139  have at least roughly the same distance to each other and are parallel to each other in this practical example. The staggering of light deflection surfaces  132 - 139 , the distance of the individual crest levels  34 ,  35 ;  34 ,  36  relative to each other, diminishes with increasing distance of the light deflection surface  132 - 139  from light reflector  126 . 
   The light deflection surfaces  132 - 139  can also consist of several individual surfaces. 
   The light bundle  102 - 109  reflected on the light deflection surfaces  132 - 139  is largely homogeneous, since the lower light intensity in the sections distant from the light reflector  126 ,  127  is compensated by a larger light deflection surface  132 - 139 . 
   The homogeneously distributed light  101 - 109  impinges on the interfaces of the optical waveguide element  10 , formed by the notch surfaces  52 ,  53 . The two interfaces enclose the complementary angle of the V-shaped notch  51  of 360 degrees, i.e., at least an angle of 260 degrees. They form a deflection-light divider  151 , whose imaginary plane of symmetry is aligned normal to the imaginary plane of symmetry of the light divider  125 . The deflection-light distributor  151  has two reflection surfaces  152 ,  153 , on which the impinging light  101 - 109  is deflected upward and downward in the depiction of  FIGS. 1 and 3 . By arching of the reflection surfaces  152 ,  153 , the light reflected on them  101 - 109  is bundled. Optionally, the surfaces  152 ,  153  can have scattering optics that scatter the light  101 - 109  in the longitudinal direction of the optical waveguide element  10 . The reflection surfaces  152 ,  153  of the deflection-like distributor  151  and/or the light deflection surfaces  130 - 140  can have scattering optics  166 . 
   The light  101 - 109  reflected on the deflection-light divider  151  impinges on the interfaces of the optical waveguide element  10 , which are formed by the boundary surfaces  66 ,  86  of the longitudinal notches  63 ,  83 . The surface elements  67 ,  87  form segmented total reflection optics  166 , which deflect the impinging light  101 - 109  in the direction of the light outlet surfaces  71 ,  91 . The light  101 - 109  here is fanned out in the longitudinal direction of the optical waveguide element  10  by means of the semi-cylindrical reflection elements  167 , depicted in  FIG. 5 . The reflection elements  167  can also be sections of cylindrical segments, whose segment angle is smaller than 180 degrees. The base surface of the cylinder can also be bounded by a parabolic section, an elliptical section, etc. The optical axis of the reflection elements  167  depicted here can also form an angle not equal to ninety degrees with the longitudinal axis of the optical waveguide element  10 . 
   The light bundle  102 - 109  reflected and widened in this way passes into the surroundings  1  through light outlet surfaces  71 ,  91 . The imaginary axes of the light outlet surfaces  71 ,  91 , for example, are parallel to the imaginary plane of symmetry of the deflection-light divider  151 . 
   During operation of lighting assembly  2 , the light outlet surfaces  71 ,  91  appear as homogenously illuminated surfaces. The light outlet surfaces  71 ,  91  can therefore be freely configured in producing lighting assembly  2  and can be adapted to the auto body of the vehicle and, for example, follow its external contour. The light outlet surfaces  71 ,  91  appear as surfaces, for example, optically smooth. 
   The lighting assembly  2  can be constructed non-symmetrically. The light deflection surfaces  132 - 139  can be illuminated directly by light source  6 . The lighting assembly  2  can also have several light sources  6  and/or several optical waveguide elements  10 . 
   Only limited incorporation space is required for the lighting assembly  2  in the vehicle. By arranging the light source  6  on the back side  11 , the lighting assembly  2  can be incorporated flush on the side. For example, several lighting assemblies  2  can be arranged next to each other and two parallel, uninterrupted, long, homogenously illuminating light bands can be produced. The arrangement of several lighting assemblies  2 , one above the other, is also conceivable. 
   In the depiction of  FIGS. 1 to 3 , the radiation direction  9  lies normal to an imaginary tangential plane of the two light outlet surfaces  71 ,  91 . The light source  6  can also be arranged, so that the radiation direction  9  forms an acute solid angle with the tangential plane. 
   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.