Abstract:
A light fixture suitable for illuminating a remote surface. The fixture includes a post adapted to receive at least two substantially identical light engine modules. Each module includes a plurality of light emitting diodes. Each module includes an edge adapted for mounting to the post.

Description:
BACKGROUND 
       [0001]    The present disclosure relates to the art of lighting fixtures, and more particularly to area lighting fixtures for distributing patterns of light on the ground. These lighting fixtures can be used for area lighting, including street, parking lot, walkway, bicycle path, or other similar applications. Additionally, these lighting fixtures can be employed for indoor applications, such as, illuminating basketball or factory building floors. 
         [0002]    In general, lighting fixtures consist of a lamp or other light source, and a reflector for reflecting light from the light source. The shape of the reflector and any shielding typically define the light distribution pattern. More particularly, the light pattern is either controlled by external shielding, for high intensity discharge lamps, or by an optical package for light emitting diode packages. Since shielding is an inefficient blocking of otherwise useable light, the HID solution wastes light power that is not directed in the desired direction. 
         [0003]    Light energy spreads over distance. The illumination of a remote area therefore varies inversely as the square of the distance from the light source. Additionally, since light fixtures directing light to a relatively large target area, the light source is many times smaller than the area to be lighted. Accordingly, the beam of light energy produced by each fixture must be relatively intense to cover a substantial area. 
         [0004]    These characteristics present certain lighting problems. First of all, to maintain a given light level at a distant target area, the light source must produce a much higher level of light energy at the source. This can contribute to glare problems for those viewing the fixtures. Secondly, the use of diverging or converging beams can result in a significant amount of light falling outside the target area. This results in spill. Spill and glare are inefficient use of the light and are frequently objectionable. 
         [0005]    Spill in parking, street and highway lighting results in wide-scale lighting of areas, which makes the actual roadway less distinct from surrounding areas. Additionally, lack of control also translates, in many applications, into the utilization of more light poles and lighting fixtures, which is expensive and consumes substantial resources. 
         [0006]    Also, most existing light systems have broadcast or spread light over as much of the highway or roadway as possible. However, by doing so, some light is most times projected toward the driver rather than away from the driver in the driver&#39;s viewing direction for each lane of the highway. This can contribute to glare for drivers on the roadway. 
         [0007]    In certain environments, square distribution lighting fixtures may be preferred by lighting architects. To illuminate a parking lot, for example, the lighting architect can employ fewer lighting fixtures because overlap of distribution patterns can be eliminated. Additionally, lighting architects can eliminate spill at the corners and edges of the parking lot by using a square lighting distribution. Alternatively, round or oval light distributions can be the most efficient wherein little or no shielding of light is necessary. 
         [0008]    Having a light engine which is selectively modifyable to provide a wide array of light distribution patterns allows precise control of light. One advantage of the present disclosure is that by providing an adaptable modular lighting fixture, it is feasible to readily select fixture modules having suitable light distribution and orientation to properly light almost any area or shape with minimal spill and limited viewer glare. 
       BRIEF DESCRIPTION 
       [0009]    According to one embodiment, a light fixture suitable for illuminating a remote surface is provided. The fixture comprises a post adapted to receive at least two substantially identical light engine modules. The modules include a plurality of light emitting diodes. Each module has a light emitting diode inclusive surface and an opposed surface. Each module further includes an edge adapted for mounting to the post. The fixture also includes an electrical path for providing electrical power to the modules. 
         [0010]    According to another embodiment, a light fixture comprising a post adapted to selectively receive up to four light emitting diode modules is provided. Each module comprises a first edge adapted for mating with the post and a second arcuate edge extending approximately 90°. The light fixture can include four modules to form a substantially circular shape. 
         [0011]    According to a third embodiment, a light engine module for a light fixture is provided. The module comprises a body housing at least two separable light emitting diode arrays. An electronic conversion element for converting AC to DC is also provided. The module further includes a mounting arm extending from the body. 
         [0012]    According to a further embodiment, a light fixture is provided. The fixture includes a post having at least two light engine modules mounted thereto. The modules include at least two light emitting diode arrays wherein the light emitting diodes are in a substantially hemispherical distribution. The arrays of the first module are oriented relative to one another differently than the arrays of the second module. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a bottom perspective view of a modular area light fixture assembly; 
           [0014]      FIG. 2  is a top perspective view of the assembly of  FIG. 1 ; 
           [0015]      FIG. 3  is a bottom perspective view of an individual lamp module; 
           [0016]      FIG. 4  is is a top perspective view of the module of  FIG. 3 ; 
           [0017]      FIGS. 5  ( a ), ( b ) and ( c ) are perspective views demonstrating the adaptability of the present assembly; 
           [0018]      FIG. 6  is a bottom perspective view of an alternative module design; 
           [0019]      FIG. 7  is a top perspective view of the module of  FIG. 6  and; 
           [0020]      FIGS. 8  ( a ), ( b ), ( c ) and ( d ) demonstrate the further adaptability of the modules achieved via orientation of the LED arrays. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    Referring now to  FIGS. 1 and 2 , a modular area light fixture  10  is depicted. Fixture  10  includes post  12  to which light modules  14  are removably mounted via screws or bolts  16 . With four modules  14  secured to post  12 , a light pattern extending 360° is provided. Moreover, each module  14  comprises a sector of a circle having an arcuate outer edge  17  traversing approximately 90°. 
         [0022]    More particularly, each module  14  includes LEDs (light emitting diodes)  18  disposed upon a bottom surface  20 . Surface  20  can be reflective to improve light extraction from the fixture. Top surface  22  of each module  14  includes a plurality of vanes  24  to enhance heat dissipation. 
         [0023]    Referring now to  FIGS. 3 and 4 , an individual light module  14  is depicted. The individual light module  14  encompasses an area of approximately 90°. In this regard, each module represents a one quarter sector of a circle. The sides of the module  14  are bounded by shoulder elements  26  which meet at inner edge  28  to form a collar element  30 . Collar element  30  includes an arcuate shaped surface which is cooperative with the outer surface of post  12 . Of course, any suitable cooperative shape between the post and collar element  30  will be acceptable. Passages  32  are formed in collar element  30  to facilitate the removeable attachment of module  14  via bolts or screws to post  12 . Some type of mating between the shoulder elements  26  of adjacent modules, such as a clip or other mechanical joinder, may be desirable to increase overall light fixture strength. Power is provided between an end  33  of post  12  via flexible conductors or other circuitry (not shown) and the individual LED arrays. 
         [0024]    Turning now to  FIG. 3 , the LEDs  18  are disposed in four generally concentric arrays  34 ,  36 ,  38  and  40 . The LEDs are set in concentric arcuate paths. When all four modules  14  are in place, several concentric rings of LEDs are formed (see  FIG. 1 ). Of course, any type of LED distribution on surface  20  as dictated by the desired light distribution for the particular application is contemplated by the present disclosure. The LEDs can be of any type known to the skilled artisan including white light generating, saturated color generating of a mixture thereof. In addition, the LEDs can be individually packaged to include an integral optical element or the LEDs can be unpackaged and an optical element could be formed over the entire surface  20 . 
         [0025]    Turning next to  FIG. 5 , the functionality achievable by the modularity of the light fixture  10  is demonstrated. Moreover, in  FIG. 5(   a ), by providing a single module  14  on post  12 , a light dispersion of approximately 90° can be obtained. In this regard, placing the fixture of  FIG. 5(   a ) in, for example, the corner of a parking lot, could provide suitable lighting of the corner area without light spill outside of the parking area. 
         [0026]    Turning now to  FIG. 5(   b ), approximately 180° of light distribution is provided by light fixture  10  which includes two adjacent modules  14 . This light distribution could be suitable, for example, in lighting of an edge of a parking area, or a sidewalk or other applications wherein a linear demarcation exists between the area to be lit and an outlying area. 
         [0027]    Referring now to  FIG. 5(   c ), a symmetric light distribution pattern is provided by including two modules  14  an opposed sides of post  12 . This orientation can be used when, for example, illuminating a central area of a parking area or perhaps down the center of a highway where lanes on each side are being illuminated. 
         [0028]    Referring now to  FIGS. 6 and 7 , an alternative design of a module  140  is depicted. Module  140  includes a housing  142 , within which a pair of LED arrays  144  are disposed. LED arrays  144  are substantially identical units which can be individually attached to module  140  and separately powered. LED arrays  144  are more particularly comprised of a reflective substrate  146  upon which a plurality of hemispherical LED arrays  148  and  150  are disposed. As shown reflective substrate  146  includes a surface shaped to create a slightly directed (see arrows  147 ) light distribution. Housing  142  further includes a compartment covered by a door  152  which includes electronic circuitry (not shown) for converting alternating current to direct current. Housing  142  is further provided with an arm  154  including bracket  156  suitable for mating with a post. 
         [0029]    Turning now to  FIG. 8 , the ability of the present embodiment to provide highly tuned light distributions is depicted. Moreover, in addition to the ability to have between 90 and 360° of light distribution (see  FIG. 5 ), each individual module can be tailored by modifying the orientation of LED arrays  144 . For example, with reference to  FIG. 8(   a ), LED arrays  144  are oriented with opposed array directions such that a symmetrical light distribution (i.e., 360° from the module) is provided. In contrast, referring to  FIG. 8(   b ) an asymmetric right light distribution ( 147 ) and in  FIG. 8(   d ) and an asymmetric left light distribution ( 147 ) is provided. This can advantageously direct light down onto a street but also canted in the direction a vehicle is being driven. In this manner, glare experienced by the vehicle operator can be reduced. With further reference to  8 ( c ), a forward light distribution ( 147 ) is provided. 
         [0030]    The present disclosure describes modules allowing the number placed on a pole along with the orientation on the pole to dictate the illumination pattern on the ground. This can reduce the acquisition cost since only the number of modules required on each pole must be purchased. Furthermore, since the modules are substantially identical the production costs can be controlled. There are not different part numbers to track and manufacture for various light patterns, because only one light engine module that can satisfy all light patterns needed. Similarly, since the same heat sink and other parts can be used, cost of manufacturing and maintenance is reduced. However, the modules can be attached to the post in varying numbers, e.g., 1 to 4, and since the LED arrays in each module can be oriented left, right or forward, as desired, the light pattern emitted by the fixture is highly flexible. 
         [0031]    The exemplary embodiment has been described with reference to the preferred embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the exemplary embodiment be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.