Abstract:
The present invention is a lighting arrangement having at least one light source, light at least two light pipes for receiving light from the light source, and a lens having two or more sections. The lens is configured to receive light from at least one of the at least two light pipes, wherein each one of the sections projects light in a desired isomeric beam pattern.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to lenses used in conjunction with LED lights to produce a desired beam pattern. 
       BACKGROUND OF THE INVENTION 
       [0002]    Typical projector lamps incorporate a reflector and a light shield. The reflector creates a smooth distribution of light that is imaged by an aspheric convex lens onto the road. Projector lamps can also be used along with light emitting diodes (LED) to provide light that is distributed through light guides, typically in the form of fiberoptic cables, and deflected through the lens. The LEDs can provide a uniform light, points of light, or be surrounded by dark areas. If a normal lens is used along with the LEDs, the resulting beam pattern will exhibit any present dark patches. Additionally, performing additional functions of the projector lamp, such as high-beam and low-beam functions, also requires controlling the light from a second array of LEDs, so that they combine with the distribution of the original set of LEDs to produce a head lamp beam pattern. Additional LEDs may be illuminated to create a high beam or fog lamp functions. Other LEDs may be used to produce light bending functions to aid in seeing around corners. Simply imaging these arrays would not create a beam pattern that can meet the required optical performance. Applying a second standard spreader lens to be used with the LEDs could achieve the required blending; however, it would increase the number of parts, and decrease the system performance by introducing additional fresnel losses into the optical system. Adding additional optical elements between the projector lens and the luminous patches would likewise add additional parts and decrease system performance. 
         [0003]    Accordingly there exists a need for a lens which can be used with two or more sets of LEDs to produce various types of beam patterns. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention is a lighting arrangement having at least one light source, light at least two light pipes for receiving light from the light source, and a lens having two or more sections. The lens is configured to receive light from at least one of the at least two light pipes, wherein each one of the sections projects light in a desired isomeric beam pattern. 
         [0005]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0007]      FIG. 1  is a perspective view of a lens and a light pipe bundle, according to the present invention; 
           [0008]      FIG. 2  is a front view of a major group of light pipes, a minor group of light pipes, and an auxiliary group of light pipes, according to the present invention; 
           [0009]      FIG. 3  is a front view of a lens divided into horizontal segments, according to the present invention; 
           [0010]      FIG. 4  is a graph depicting a group of isocurves used for producing a high-beam pattern and a low-beam pattern, produced by a lens, according to the present invention; 
           [0011]      FIG. 5  is a graph of a first group of isocurves, along with a first source isocurve, produced by a lens, according to the present invention; 
           [0012]      FIG. 6  is a graph of a second group of isocurves, along with a second source isocurve, produced by a lens, according to the present invention; 
           [0013]      FIG. 7  is a side view of a graph depicting a lens moved along a vertical plane to create one of the segments shown in  FIG. 3 , according to the present invention; 
           [0014]      FIG. 8  is a lens according to the present invention, taken along lines  8 - 8  of  FIG. 7 , 
           [0015]      FIG. 9  is a perspective view of a lens and mounting assembly, according to the present invention; 
           [0016]      FIG. 10  is an alternate embodiment of a major group of light pipes and a minor group of light pipes, according to the present invention; 
           [0017]      FIG. 11  is a front view of an alternate embodiment of a major group of light pipes, a minor group of light pipes, and an auxiliary group of light pipe, according to the present invention; and 
           [0018]      FIG. 12  is a perspective view of an alternate embodiment of a lens, according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0019]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
         [0020]    Several components of a lighting arrangement according to the present invention are shown generally in  FIG. 1  at  10 . The lighting arrangement  10  includes a lens  12  and a light pipe bundle  14 . The light pipe bundle  14  is used for directing light toward the lens  12  from a light source (not shown).  FIG. 2  shows a front view of the light pipe bundle  14 , in this view, the light is being directed from the light source through the light pipe bundle  14  out of the page. The light pipe bundle  14  includes at least one light pipe, and more preferably includes a group of major light pipes  16  receiving light from a first light source, a group of minor light pipes  18  receiving light from a second light source, and a group of auxiliary light pipes  20 . The light pipes  16 ,  18 ,  20  of the present invention could be fiber optic cables, or could also be a combination of an LED (Light Emitting Diode) or group of LED&#39;s with closely coupled optics. The light pipes  16 ,  18 ,  20  of the present invention could also be LED&#39;s with direct imaging. 
         [0021]    In this embodiment the auxiliary light pipes  20  are divided into a group of first auxiliary light pipes  22 , a group of second auxiliary light pipes  24 , a group of third auxiliary light pipes  26 , a group of fourth auxiliary light pipes  28 , a group of fifth auxiliary light pipes  30 , and a group of sixth auxiliary light pipes  32 . The major light pipes  16 , minor light pipes  18 , and auxiliary light pipes  20  can be used to perform various lighting functions, such as producing a high-beam, a low-beam, or a turn signal in an automobile. More specifically, the major light pipes  16  can be used to produce a wide beam pattern, and the group of minor light pipes  18  can be used to produce a “hot spot” beam, where an area of light is intensified. The auxiliary light pipes  20  can be used to produce a light bending function, as well as additional hot spot beam patterns. 
         [0022]    Referring back to  FIG. 1 , the lens  12  is divided into various horizontal sections, shown generally at  34  and vertical sections, shown generally at  36 . The shape of the horizontal sections  34  and the vertical sections  36  depends on the desired light beam pattern. Referring to  FIGS. 4-6 , an example of a desired beam pattern is generally shown at  48 . The desired beam pattern  48  is divided into several isocurves. The beam pattern  48  may have as many isocurves as needed to produce the desired beam pattern  48  with the desired hotspot. In this embodiment, a portion of the beam pattern  48  is made up a first group of isocurves produced by the major light pipes  16  shown as the first isocurve  50 , second isocurve  52 , third isocurve  54 , fourth isocurve  56 , and fifth isocurve  58 . The remaining portion of the beam pattern  48  is made up of a second group of isocurves produced by the minor light pipes  18  shown as sixth isocurve  60 , a seventh isocurve  62 , an eighth isocurve  64 , and a ninth isocurve  66 . 
         [0023]    The isocurves  50 ,  52 ,  54 ,  56 ,  58 ,  60 ,  62 ,  64 ,  66  are shown in  FIGS. 4-6  on a horizontal axis  68  and a vertical axis  70 , and represent the area that the desired beam pattern  48  will illuminate. Each isocurve  50 ,  52 ,  54 ,  56 ,  58 ,  60 ,  62 ,  64 ,  66  is of a different intensity and illuminates a different area of the desired beam pattern  48 . 
         [0024]    The first set of isocurves  50 ,  52 ,  54 ,  56 ,  58  are shown in  FIG. 5 . Also shown in  FIG. 5  is a typical first source isocurve  72 . The first source isocurve  72  is the type of isocurve produced when the major light pipes  16  are used along with a simple aspheric projector lens, for example the base lens  73  shown in  FIG. 7 , having the appropriate focal length, and not the modified lens  12  of the present invention. The focal length chosen must be no shorter than one that will produce an image with a height that is no more than twice the distance from the center of the smallest zone to be illuminated and the horizontal axis  68 . Images that are larger cannot be blended to produce the desired vertical image size and will result in patterns taller than desired. 
         [0025]    The second set of isocurves  60 ,  62 ,  64 ,  66  are shown in  FIG. 6 , along with a typical second source isocurve  74 . The second source isocurve  74  is the type of isocurve produced when the minor light pipes  18  are used along with a simple aspheric projector lens, such as the base lens  73  shown in  FIG. 7 , having the appropriate focal length, and not the modified lens  12  of the present invention. The focal length chosen must be no shorter than one that will produce an image with a height that is no more than twice the distance from the center of the smallest zone to be illuminated and the horizontal axis  68 . Images that are larger cannot be blended to produce the desired vertical image size and will result in patterns taller than desired. 
         [0026]    In order to have the major light pipes  16  produce isocurves  50 ,  52 ,  54 ,  56 ,  58  when used with the lens  12  of the present invention, instead of first source isocurve  72  when the major light pipes  16  are used with the base lens  73 , and for minor light pipes  18  to produce isocurves  60 ,  62 ,  64 ,  66  when used with the lens  12  of the present invention, instead of second source isocurve  74  when the minor light pipes  18  are used with the base lens  73 , the following steps for producing the shape of the lens  12  of the present invention will now be described. 
         [0027]    The first step in defining the shape of the lens  12  is to determine the lumen content (amount of luminous flux) of the portion of the desired beam pattern  48  produced by isocurves  50 ,  52 ,  54 ,  56 ,  58  by integrating the intensity of isocurves  50 ,  52 ,  54 ,  56 ,  58  over the angular area covered by the isocurves  50 ,  52 ,  54 ,  56 ,  58 . The lumen output produced by the major light pipes  16  and controlled by the lens  12  is determined by integrating the intensity defined in the first source isocurve  72  (produced by the major light pipes  16  when projected through the aspheric projector lens described above) over the angular area covered by the first source isocurve  72 . 
         [0028]    The lumen content of the portion of the desired beam pattern  48  produced by isocurves  50 ,  52 ,  54 ,  56 ,  58  and the lumen content produced by the major light pipes  16  to create the first source isocurve  72  must be nearly equal. The reason for this is that the lens  12  of the present invention is using the light produced by the major light pipes  16 , which produce the first source isocurve  72  when used with the base lens  73 , to produce the portion of the beam pattern  48  made up of isocurves  50 ,  52 ,  54 ,  56 ,  58  by projecting the light from the major light pipes  16  through the lens  12  of the present invention. If the lumen contents are not equal, then light intensity or area coming from the major light pipes  16  must be increased, or the desired light intensity defined by isocurves  60 ,  62 ,  64 ,  66  must be reduced by sacrificing performance (or the amount of light required) between the isocurves  50 ,  52 ,  54 ,  56 ,  58  and the isocurves  60 ,  62 ,  64 ,  66  and rebalancing the system by adjusting the location and/or intensity of the fifth isocurve  58  and sixth isocurve  60 . Once the balance of available vs. desired lumen contact is achieved for isocurves  50 ,  52 ,  54 ,  56 ,  58  and isocurves  60 ,  62 ,  64 ,  66  the detailed shape of the surface of the lens  12  can be defined. 
         [0029]    Referring back to  FIG. 3 , one of the steps for producing the shape of the lens  12  is achieved by taking the base lens  73 , and dividing the base lens  73  into horizontal segments  38 ,  40 ,  42 ,  44 ,  46 . The size of each horizontal segment  38 ,  40 ,  42 ,  44 ,  46  is selected such that each segment controls the same amount of lumen content required by an associated isocurve. The amount of lumen content of each of the isocurves  50 ,  52 ,  54 ,  56 ,  58 ,  60 ,  62 ,  64 ,  66  is determined by a process of looking at each of the isocurves  50 ,  52 ,  54 ,  56 ,  58 ,  60 ,  62 ,  64 ,  66  individually taken as a separate component of the beam pattern  48 . 
         [0030]    Beginning with the isocurve having the lowest intensity, the first isocurve  50 , the lumen content is calculated by integrating over the isocurve&#39;s  50  area, assuming the entire area is of uniform intensity. The average light intensity of the area of the first isocurve  50  is then subtracted from the area of all the other isocurves  52 ,  54 ,  56 ,  58 ,  60 ,  62 ,  64 ,  66 . The lumen content of the isocurve having the next lowest intensity, in this embodiment the second isocurve  52 , is then calculated using the same steps used to calculate the lumen content of the first isocurve  50 . This process continues until the lumen content of each isocurve  50 ,  52 ,  54 ,  56 ,  58 ,  60 ,  62 ,  64 ,  66  is determined. Once the lumen content of each of the isocurves  50 ,  52 ,  54 ,  56 ,  58 ,  60 ,  62 ,  64 ,  66  is determined, then size of each of the segments  38 ,  40 ,  42 ,  44 ,  46  can then be determined. The process for determining the size of each of the segments  38 ,  40 ,  42 ,  44 ,  46  is repeated until the lens area required to control the lumen content of each of the isocurves  50 ,  52 ,  54 ,  56 ,  58 ,  60 ,  62 ,  64 ,  66  is attained. 
         [0031]    To create each of the segments  38 ,  40 ,  42 ,  44 ,  46  the following steps are taken. Referring to  FIGS. 3 and 7 , and beginning with fifth horizontal segment  46 , and the first isocurve  50 , the angular distance, indicated generally at  76 , is determined by calculating the angular distance between the center of the first isocurve  50 , and the center of the source isocurve  72  in  FIG. 5 . This forms an angle  78  having a first ray  80  and a second ray  82  which intersect at a vertex  84 . The base lens  73  also includes an axis  86  and a focal plane  88  which intersect perpendicularly to form a first intersection point  90 . The base lens  73  also has a rear plane  92  which intersects perpendicularly with the axis  86 . The angle  78  is positioned such that the vertex  84  is aligned with the first intersection point  90 , and one of the rays, in this embodiment the second ray  82 , is aligned with the axis  86 . When in this position, the first ray  80  intersects the rear plane  92  to form a second intersection point  94 , and the second ray  82  intersects the rear plane  92  to form a third intersection point  96 . The base lens  73  is shifted the distance between the second intersection point  94  and the third intersection point  96 , shown as a vertical distance  97 . An upper boundary  98  and lower boundary  100  are chosen and are dependent upon the area to be covered by each isocurve. The portion of the base lens  73  located between the upper boundary  98  and lower boundary  100  after the lens  73  is shifted forms the fifth horizontal segment  46 , which forms a portion of the shape of the lens  12 . 
         [0032]    Once the segment  46  is created, the segment  46  is further divided into multiple horizontal subsegments, generally shown at  102  in  FIG. 8 . Depending on the size of the subsegments  102 , the distance between the source isocurve  72  and the desired spread of the isocurve  50 , a concave radius of curvature  104  and a convex radius of curvature  106  can be calculated to allow the light from the isocurve  50  to be deflected over the desired angle. The concave radius of curvature  104  must be larger than the convex radius of curvature  106  due to the divergent characteristics of the light emitted from the major light pipes  16 . The concave radius of curvature  104  and convex radius of curvature  106  are positioned in alternating fashion to form the lens  12 , and the concave radius of curvature  104  connects to the convex radius of curvature  106  at interconnection points  108  between each of the concave radius of curvatures  104 , the convex radius of curvatures  106 , and the subsegments  102 . Note that only a portion of the concave radius of curvature  104 , shown as a concave arc  110 , and a portion of the convex radius of curvature  106 , shown as an arc  112  are used to form the lens  12 . 
         [0033]    Once the fifth segment  46  is formed, the process described above is repeated for each isocurve and each segment, until the lens  12  shown in  FIG. 1  is complete. Once the lens  12  is complete, the lens  12  can be installed onto a lamp assembly  114  as shown in  FIG. 9 . The lamp assembly  114  has a base  116 , and a support member  118  for supporting the lens  12 . 
         [0034]    The present invention is not limited to the embodiments previously described. Instead of having major light pipes  16 , minor light pipes  18 , and auxiliary light pipes  20 , the present invention can also simply have major light pipes  16  and minor light pipes  18 , and the various light pipes can be arranged in different ways. The major light pipes  16  can be arranged above the minor light pipes  18 , as shown in  FIG. 10 . Also, the major light pipes  16 , minor light pipes  18 , and auxiliary light pipes  20  can be packed tightly together to form a lighted segment, as shown in  FIGS. 2 and 10 , or each of the major light pipes  16 , minor light pipes  18 , and auxiliary light pipes  20  can be a single large pixel, as shown in  FIG. 11 . 
         [0035]    It should also be noted that the process for defining the shape of the lens  12  of the present invention is not limited to the lenses described above. The process can also be applied to a lens of Fresnel type optics as shown in  FIG. 12  if a reduced maximum thickness is required. 
         [0036]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.