Abstract:
A lighting module has an array of solid-state light sources on a substrate, a reflector channel arranged adjacent to the array of solid-state light sources, the reflector channel having curved, reflective inner surfaces arranged to increase collimation of light emitted from the light sources in one axis of light. A method of manufacturing a lighting module includes providing a substrate, mounting an array of solid-state light sources on the substrate, manufacturing a reflector channel, wherein the size and arrangement of the reflector channel depends upon the array of light sources, and arranging the reflector channel on the substrate such that light emitting from the light sources will be reflected in a desired direction

Description:
BACKGROUND 
       [0001]    Using solid-state light sources, such as light emitting diodes (LEDs) and laser diodes, has several advantages over traditional lamps. Solid-state light sources generally use less power, generate less heat and have higher reliability. Some modifications may increase their effectiveness and efficiency even more. 
         [0002]    For example, LEDs generally emit light in a hemispherical pattern that may benefit from some directional control. One solution involves directing the light from the LEDs towards a reflective surface, which in turn redirects the light without increasing collimation. U.S. Pat. No. 6,149,283 to Conway, et. al., issued Nov. 11, 2000, discloses an example of this approach. 
         [0003]    In another approach, disclosed in U.S. Pat. No. 5,130,761, to Tanaka, issued Jul. 14, 1992, a flat reflective surface receives the light from an LED mounted on the substrate. The reflective surface then directs some of the light in a direction generally parallel to the substrate. 
         [0004]    U.S. Pat. No. 6,683,421, issued Jan. 27, 2004, to Kennedy, et. al., wedge-shaped, straight-walled reflective pieces are inserted between the LEDs on a substrate to redirect sidewall light in a different direction. Sidewall light is light that the LED emits parallel with the substrate. 
         [0005]    None of these approaches serve to increase the collimation of the light emitted from the LED. They generally address directing the light in whole in a particular direction, or, in the case of Kennedy, capturing a particular type of light leakage. They do not address increasing the collimation of the light from an LED into a particular direction to increase the overall efficiency and the peak radiance of a lighting fixture. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  shows a side view of an embodiment of a reflector channel for a solid-state light source. 
           [0007]      FIG. 2  shows an embodiment of an array of solid-state light sources on a substrate. 
           [0008]      FIG. 3  shows a ray diagram of solid-state light source emissions without a reflector channel. 
           [0009]      FIG. 4  shows an embodiment of an array of solid-state light sources having a reflector channel. 
           [0010]      FIG. 5  shows a ray diagram of solid-state light source emissions with a reflector channel. 
           [0011]      FIG. 6  shows a side view of an alternative embodiment of a reflector channel for an array of solid-state light sources. 
           [0012]      FIG. 7  shows a detailed side view of an alternative embodiment of a reflector channel for an array of solid-state light sources. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0013]      FIG. 1  shows a side view of a light module  10 . The light module  10  has a reflector channel  12  for use with an array of solid-state light sources, which can only be seen as a single light source  14  in this view. The reflector channel may be viewed as an assembly of different pieces or components. The reflector channel  12  has inner surfaces, which may be manufactured out of different pieces of material, and a light channel  22 . 
         [0014]    The light source  14  resides on a substrate  16 . The substrate may consist of silicon, glass, ceramic, diamond, SiC, AlN, BeO, Al 2 O 3 , or combinations of these or other materials, may be thermally conductive, and may be electrically insulative. These are just examples of possible materials, and are not intended in anyway to limit the scope of the invention as claimed. 
         [0015]    The reflector channel  12  will generally consist of a piece or pieces of material that form curved, inner surfaces such as  18  and  20 , arranged on either side of the light source  14 . For some applications, only one of the inner surfaces may be used. The reflector channel  12  defines the light channel  22  through which light is directed towards a surface to be illuminated  24 . Generally, the surfaces  18  and  20  will have a shape designed to collimate or concentrate the emitted light. 
         [0016]    The reflector channel may be made from one piece of material with gaps in it to accommodate the light sources, or may be made from two pieces of material, each mounted on a side of the light sources. The material may consist of metal, polymers or plastics, including PVC (polyvinyl chloride). A metal that generally works well is aluminum, especially if the application involves curing using UV light, as aluminum has high reflectivity in the UV band. The reflector channel may be made of a soft metal from which the reflector shape can be stamped. 
         [0017]    If the reflector channel is formed from a polymer or plastic, it may require some further processing to ensure high reflectivity. A reflective coating may be added to the reflector structure using thin film processes or other type of coating processes. One example coating includes Alzak™ by the Aluminum Company of America (ALCOA). 
         [0018]    The reflector channel may be formed by cutting, stamping, injection molding or extrusion. Designs that use individual reflectors for each light source generate a high irradiance spot. When these spots are stacked end to end to create a line of light at a target surface, there is a trade off between uniformity and irradiance. The reflector channel could be extruded to a desired length with the curved inner surface or surfaces as needed which maintains uniform high irradiance light over the entire length at the target surface. 
         [0019]    In one example, the light pattern desired at the surface  24  is a single or multi-line pattern. The lines of light need relatively high radiance in a relatively narrow space. The concentration or collimation of the light from the light source into the line pattern increases the irradiance at the surface.  FIG. 2  shows an array of light sources such as  14  arranged in a line pattern. 
         [0020]    As shown in  FIG. 3 , the light source  14  emits light in a nearly-hemispherical pattern. The desired light pattern on surface  24  is essentially a line, shown by the region  26 . Without some sort of optics or collimation, much of the light from the light source  14  will not reach the desired region. Further, the light that does reach the region will not have sufficient irradiance to effect the desired change. 
         [0021]    One application, for example, of these types of lighting modules is curing of inks, adhesives and other coatings. Some of these curing applications use ultraviolet (UV) light, but all types of wavelengths should be considered. The coating resides on surface  24  and may have a necessary level of irradiance to effect the curing operation. By collimating the light into the line pattern, the lighting module can produce enough irradiance to cure the coating. 
         [0022]      FIG. 4  shows the substrate  16  of  FIG. 2  with the reflector channel  12  added. The reflector channel  12  may be mounted to the substrate using adhesives, brackets, screws, etc. 
         [0023]      FIG. 5  is a ray diagram showing the resulting alteration of the light pattern. Referring back to  FIG. 3 , one can see that the light sources by themselves produced light in a near-hemispherical pattern. In  FIG. 5 , the same light source produces light in a near hemispherical pattern, but the resulting light pattern is much more collimated. The irradiance received in region  26  is significantly higher. Experiments show that the irradiance achieved using  FIG. 5  is 204% of that achieved with  FIG. 3 . 
         [0024]    While the discussion up to this point has focused on the production of a single line pattern, the reflector channel could also be used in arrangements where multiple line patterns could be produced. For example, the array of  FIG. 2  is an array forming one column of single light sources. It is possible to have an array arranged on an x-y grid. It should be noted that the array of  FIG. 2  is actually on an x-y grid, with one column on the x-axis. However, to differentiate that arrangement from one having more than 1 column, the term ‘x-y grid’ will be used for an array having two or more columns of light sources. 
         [0025]      FIG. 5  shows an array of light sources such as  14  on the substrate  16 . In this view, the array of light sources is arranged in an x-y grid, from left to right being defined as the x-axis, y-axis coming out of the page. Each column would have a reflector channel, such as  12 , and  30 , resulting in a light pattern having multiple bars of light exiting the light channels of the reflectors in the z-axis. 
         [0026]    In the embodiment where a reflector channel resides between two adjacent columns of light sources, the profile of the reflector channel may differ from that shown in  FIG. 1 . As can be seen in  FIG. 7 , the reflector channel pieces such as  30  that reside between adjacent columns of light sources will have two curved surfaces, each a curved, inner surface but facing in opposite directions from each other. Reflector channel  12  has curved surfaces  18  and  20 , as shown in  FIGS. 1 and 7  where  18  and  20  are not necessarily the mirror image of the other. Reflector channel  30  has curved surfaces  34  and  36 , with curved surface  34  and curved surface  20  residing on the same piece of material. 
         [0027]    Alternatively, each reflector channel could reside separately, but this would increase the number of pieces of material necessary to provide reflector channels for the array of light sources, as well as increasing the spacing between the columns. To further increase the irradiance at the target, it is generally desirable to space the light sources closer together. Further, the size of the reflector is substantially equal to, or only slightly larger than, the size of the light source  14 . This allows for the smallest possible column spacing. 
         [0028]    It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also that various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.