Abstract:
A testing box for testing light sources, the testing box comprising: an enclosure comprising an opening for receiving a light source; a sensor of a light property for light emitted inside the enclosure; and a comparator of the light property sensed by the sensor and a shifted test box boundary for the light property, wherein the shifted test box boundary is based on a correlation between a measured light property of a test light source in an integrating sphere and a measured light property of the test light source in the testing box. A method for testing a light source for compliance with a standard, comprising: obtaining a first measurement of a first property of a first light source in a reference measuring device; obtaining a second measurement of the first property of the first light source in a testing measuring device; determining the difference between the first measurement and the second measurement; and determining an adjusted standard value based on a correlation between the first measurement and the second measurement.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claim priority to U.S. Provisional Application No. 61/373,125, filed Aug. 12, 2010, the disclosure of which is hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to methods and apparatuses for manufacturing lighting devices. More specifically, the invention relates to methods, systems, and apparatus for testing of light output and color in a manufacturing environment. 
     BACKGROUND 
     The lighting industry is in the midst of a sea change. Driven by a need to provide light sources that require less energy while providing the same amount of light as conventional devices, the industry has moved from high wattage incandescent lamps to more economical fluorescent lamps, including compact fluorescent lamps that can be used in a standard incandescent fixture. As technology continues to develop, fixtures using light emitting diodes (LEDs) have also seen some limited acceptance in the market. 
     LEDs are solid-state semiconductor devices that emit light when current is applied. LEDs can be highly advantageous over incandescent lamps because LEDs can provide a similar amount of light in a much smaller package that uses much less energy. LEDs also tend to have a much longer useful life than either fluorescent or incandescent lamps. 
     Despite the many advantages of LED lamps, several factors stand in the way of widespread adoption for household and business lighting applications. First, it is difficult to produce white light with LEDs. Traditional LED technologies result in colored light, typically in shades of red, green, or blue. Although technology exists to create white light with LEDs, this technology adds to the expense of production, and also may not reliably produce a shade of white that is pleasing to consumers, or satisfies certain legal or regulatory requirements. Further, LED lamps can have inconsistent color temperature and light output, as compared to conventional incandescent or fluorescent lamps. This leads to a requirement that each LED lamp produced be tested extensively to ensure that its light output meets specifications, including outputting light with the proper color temperature. This can be particularly important with respect to marketing. Lamp manufacturers find it advantageous to indicate the color temperature of the light output from the lamp (conventionally measured in degrees Kelvin), as well as the total light output (measured in lumens), on their packaging. Making such representation on packaging, however, requires a consistent LED product. One way to verify the consistency of color temperature and total light output of LED products is through testing every individual LED product produced. 
     Conventionally, this testing has been completed using integrating spheres. Conventional integrating spheres, as the name implies, are typically spherical in shape, have an internal surface colored flat white, and incorporating precision optical measuring equipment. Major manufacturers of integrating spheres include: Sphereoptics, Labsphere, Radiant Imaging, and Orboptronix. When a lamp is introduced into an integrating sphere, the sphere measures precisely the chromaticity values of the light output of the lamp from which color temperature is calculated (expressed in degrees Kelvin) and the total light output (expressed in lumens). Accordingly, depending on the results of an integrating sphere test, it can be determined whether the light output of a given LED lamp meets specifications so as to be appropriate for consumers. Integrating spheres, however, are very expensive, often costing many tens of thousands of dollars. For manufacturers operating multiple LED lamp manufacturing lines, the cost of integrating spheres can cause manufacturing costs to become prohibitive. Thus, it is cost prohibitive to test the chromaticity and total light output of every LED lamp manufactured via conventional integrating spheres. 
     SUMMARY 
     In accordance with the teachings of the present disclosure, disadvantages and problems associated with testing individual luminaires are overcome. 
     According to one aspect of the invention, there is provided a method for testing a light source for compliance with a standard, comprising: obtaining a first measurement of a first property of a first light source in a reference measuring device; obtaining a second measurement of the first property of the first light source in a testing measuring device; determining the difference between the first measurement and the second measurement; and determining an adjusted standard value based on a correlation between the first measurement and the second measurement. 
     According to a further aspect of the invention, there is provided a testing box for testing a light source, the testing box comprising: an enclosure comprising an opening for receiving a light source; a sensor of a light property for light emitted inside the enclosure; and a comparator of the light property sensed by the sensor and a shifted test box boundary for the light property, wherein the shifted test box boundary is based on a correlation between a measured light property of a test light source in an integrating sphere and a measured light property of the test light source in the test box. 
     Still another aspect of the invention provides a method of testing a light source, the method comprising: providing a testing box capable of accommodating the light source; measuring the chromaticity of a test light source in an integrating sphere; generating a color boundary for the measured chromaticity of the test light source in the integrating sphere; measuring the chromaticity of the test light source in the testing box; shifting the color boundary based on a correlation between the measured chromaticities of the test light source in the integrating sphere and the testing box; and measuring the chromaticity of the light source in the testing box. 
     A further aspect of the invention provides a method of testing lumen output of a light source in a testing box, the method comprising: measuring the lumen output of a test light source in an integrating sphere; measuring the lumen output of the test light source in the testing box; measuring the lumen output of a subject light source in the testing box; and determining the actual lumen output of the subject light source by multiplying the measured lumen output of the subject light source in the testing box by the measured lumen output of the test light source in the integrating sphere and dividing by the measured lumen output of the test light source in the testing box. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete understanding of the present embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features. Reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein: 
         FIG. 1  is a perspective view of a testing box having a cubic shape; 
         FIG. 2A  is a top view of a collar, which serves as a mount for a lamp and/or fixture at an opening of a testing box; 
         FIG. 2B  is a side view of the collar of  FIG. 2A ; 
         FIG. 2C  is a front view of the collar of  FIGS. 2A and 2B ; 
         FIG. 2D  is a perspective view of the collar of  FIGS. 2A-2C ; 
         FIG. 3  is a perspective view of a testing box having a fixture tray mounted to a collar; 
         FIG. 4  is a perspective view of a testing box having a fixture tray mounted to a collar, wherein a light fixture to be tested is being inserted into the fixture tray; 
         FIG. 5  is a perspective view of a test box in the shape of a parallelepiped, specifically a rectangular parallelepiped; 
         FIG. 6A  is a top view of a testing box for testing printed circuit board LED light arrays; 
         FIG. 6B  is a side view of the testing box of  FIG. 6A ; 
         FIG. 6C  is a perspective view of the testing box of  FIGS. 6A-6B ; 
         FIG. 6D  is a perspective view of the testing box of  FIGS. 6A-6C , wherein the view is from the interior of the box; 
         FIG. 7  is a perspective view of a testing box having a sensor and a fiber optic cable; 
         FIG. 8A  is a cross-sectional side view of a testing box having a sensor, a baffle and an opening; 
         FIG. 8B  is a front view of the testing box of  FIG. 8A ; 
         FIG. 9  is a 1931 CIE diagram of the x and y coordinates for chromaticity, wherein 7-step MacAdam ellipses are identified; 
         FIG. 10  is a graph of an ANSI boundary and End of Line boundary for a testing box, for a nominal color temperature 3500K; 
         FIG. 11  is a graph of an ANSI boundary and End of Line boundary for a different testing box than that of  FIG. 10 , for nominal color temperature 3500K; 
         FIG. 12  is a perspective view of an end of line testing station comprising a testing box, a power meter, a spectrometer, and a computer; 
         FIG. 13  is a flow chart of a process for end of line testing of lamps and/or fixtures, wherein light color is the testing criteria; and 
         FIG. 14  is a flow chart of a process for end of line testing of lamps and/or fixtures, whereby actual lumen output is the testing criteria. 
     
    
    
     The drawings illustrate only exemplary embodiments of the invention and are therefore not to be considered limiting of its scope, as the invention may admit to other equally effective embodiments. The elements and features shown in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of exemplary embodiments of the present invention. Additionally, certain dimensions may be exaggerated to help visually convey such principles. In the drawings, reference numerals designate like or corresponding, but not necessarily identical, elements. 
     DETAILED DESCRIPTION 
     Preferred embodiments and their advantages over the prior art are best understood by reference to  FIGS. 1-14  below. However, the present disclosure may be more easily understood in the context of a high level description of certain embodiments. 
     To reduce the manufacturing costs associated with LED lamps, methods and apparatuses are provided that allow testing of LED lamps that is sufficiently accurate as compared to testing with integrating spheres, yet much less expensive. Accordingly, one exemplary embodiment allows for reduced manufacturing cost and increased manufacturing speed. 
     Throughout this specification, the term “lamp” means a light source, for example, an LED package, a halogen light bulb, or any other light source. Throughout this specification, the term “luminaire” means a device that uses a lamp, for example, a light fixture. Throughout this specification, the term “light source” means any source of light and expressly includes both lamp and luminaire. 
     The inventive process and apparatus allows for simple and compact optical and electrical testing of every single unit produced on an LED luminaire assembly cell. The testing box may be used to test the LEDs. An in-house manufactured testing box, which is not accurate by itself, may be correlated to actual optical measurements by optical comparisons to a standard integrating sphere. Testing boxes may be custom built as to size and shape so as to accommodate the size and functionality based on each specific product to be tested. The testing boxes may be used in “end of line” testing stations, which test each LED at the ends of the production lines. 
     Testing boxes may be used to test any light color characteristic or property. For example, testing boxes may be used to test: chromaticity, lumen output, color rendering index, and wavelength. 
     In one exemplary embodiment, a testing box  10  takes the place of an integrating sphere in the testing process. One exemplary testing box is shown in  FIG. 1 . As shown in  FIG. 1 , the exemplary testing box is a rectangular shape having solid walls with an opening at one end wherein a light fixture can be attached. In certain exemplary embodiments, the interior of the testing box (not shown) may be painted with flat white paint. One exemplary testing box, shown in  FIG. 1 , may be constructed from medium density fiberboard. Alternatively, the box can be constructed from any suitable material that is sufficiently rigid so as to hold its shape, and sufficiently strong so as to be able to support a lighting unit under test. Although the exemplary box is generally shaped as a rectangular cuboid, there are no particular limitations on the size and shape of the box, other than the box may be sufficiently large such that it can support an opening sufficiently large to envelop the lamp of a given unit under test. The box can be any opaque polyhedron or other three-dimensional shape. 
     As shown in  FIG. 1 , the box  10  may include an opening  11  for receiving light from the lighting unit under test. In the exemplary embodiment, all of the light from the unit under test is received into the opening  11 . Alternatively, a portion of the light may be received into the opening. The testing box  10  may also be fitted with a collar, door, or other apparatus for coupling the lighting unit to the testing box and the opening such that the light from the lighting unit is directed into the testing box. The exemplary testing box  10  of  FIG. 1  includes an opening  11  and a collar  12  designed to receive a downlight fixture (not shown). A glass or polycarb lens or any other clear material known to persons of skill may cover the opening  11  to keep the inside of the testing box free of dirt and debris. 
       FIGS. 2A ,  2 B and  2 C show top, side and end views, respectively, of an exemplary collar  12  for coupling the testing box to a downlight fixture. The collar  12  has a cylindrical structure with two flanges extending from opposite sides of the cylinder. The flanges enable the collar to be mounted to the top of the testing box at the opening in the testing box.  FIG. 2D  illustrates a perspective view of the collar. In alternative embodiments, the collar may be a series of concentric rings that overlap each other so as to accommodate a variety of lamp fixture sizes. Thus, depending on the diameter of the lamp fixture to be tested, rings may be added/removed to/from the collar to produce a smaller/larger opening. 
     As shown in  FIG. 3 , additional testing aids may also be attached to the testing box to aid in the testing process. Attached to the testing box  10  in  FIG. 3  is a fixture tray  13  with two grooves  14  alongside the opening  11  and collar  12 . The grooves  14  in the fixture tray  13  may be disposed so as to accommodate hangar bars associated with a standard downlight fixture (not shown). When the hangar bars (not shown) are inserted into the grooves  14 , it is assured that the fixture (not shown) is in the appropriate position. 
       FIG. 4  demonstrates a downlight fixture  15  in place on the testing box  10  with collar  12  and fixture tray  13  attached. The grooves  14  in the fixture tray  13  may be disposed so as to accommodate hangar bars  16  associated with a standard downlight fixture  15 . As one of skill in the art would understand, the opening  11  and attachment mechanism would differ depending on the physical properties of the lighting fixture  15  that is to be attached thereto. 
     In an alternative embodiment shown in  FIG. 5 , a box is constructed with a door-like mechanism  18  for testing a linear fixture  19 . Also shown in  FIG. 5  is a bar code scanner  17  associated with the testing facility. The bar code scanner  17  can read a UPC code associated with a serial number of the unit under test, and can store the test results for that unit in a computer. This allows the individual test results for a given unit to be retrieved at a later time. The alternative test box  10  shown in  FIG. 5  may be made from sheet metal rather than medium density fiberboard. The test box  10  includes a rectangular opening  11  to accommodate a linear  19 , wherein the linear  19  is coupled to the door  18  by way of three clips  20 . Alternatively, one of skill in the art would understand that the linear  19  can be coupled to the door  18  through any number of methods suitable to hold the linear in place on the door  18  during the duration of the test. Power can be routed to the unit under test through the door  18  or any other portion of the testing box  10 , and switched on and off with a switch box  21  coupled to a side of the testing box  10 . In one exemplary embodiment, when the door  18  is closed, the unit under test is completely enclosed inside of the testing box  10 . 
     In yet another exemplary embodiment, the testing box can be modified to allow for the testing of LED lamps attached to printed circuit boards.  FIGS. 6A-6D  illustrate different views of an exemplary testing box  10  for the testing of LED lamps attached to printed circuit boards.  FIG. 6A  is a top view of the testing box  10 . A door-like mechanism  18  is connected to the top of the testing box  10  via a hinge  25 . A handle  26  is attached to the top of the door-like mechanism  18  for easy opening/closing. Z-shaped brackets  27  are positioned around the door-like mechanism  18  and extend down into the opening (not shown) in the top of the testing box  10 . The Z-shaped brackets  27  suspend the printed circuit board in the opening under the door-like mechanism  18 . The door-like mechanism  18  has notches at its periphery to accommodate the Z-shaped brackets  27 .  FIG. 6B  is a side view of the testing box  10  shown in  FIG. 6A . From this angle, the hinge  25  and handle  26  are clearly visible.  FIG. 6C  is a perspective view of the testing box  10  shown in  FIGS. 6A and 6B , wherein the hinge  25  and handle  26  are at opposite ends of the door-like mechanism  18 .  FIG. 6D  is a perspective view from inside the testing box of the under-side of the top of the testing box  10 . A printed circuit board  28  is suspended by the Z-shaped brackets  27  in the opening  11  of the testing box  10 . The printed circuit board  28  has an array of LEDs  29 . The door-like mechanism  18  is closed above the printed circuit board  28 . It may be the case with PCB- and MCPCB-based LED lamps that they rely on a power supply that is not integrated with the PCB. Further, in operation, the external power supply may connect to the PCB through a very small plug, such as a MOLEX connector, or through even smaller solder points. A power supply  35  is provided in the testing box  10  to supply power to the printed circuit board  28 . 
     PCB-based lamps may not always have a fixture that allows for the lamp to be sealed to a testing box (as is possible with, by way of example, the downlight fixture shown above in  FIG. 4 . Accordingly, in one exemplary embodiment, testing a PCB-based lamp includes sealing the PCB inside the box while receiving power from outside of the box. The door mechanism shown in  FIG. 6D  provides this capability. The PCB can either be mounted to the inside of the door or suspended under the door via Z-shaped brackets, and then the door may be made to seal the opening of the testing box. The test points of the power supply  35  provide connection points for an external power supply on the outside of the box, and on the inside of the box provide pins that can either contact the power supply inputs on the PCB directly, or can be wired to the power supply inputs. 
     The interior of the testing boxes may be a flat white color. The interior surface may be diffuse, matte or flat and reflective. The interior surfaces may be painted with Krylon 1502 Indoor/Outdoor flat white paint. In some embodiments, satisfactory paints are those which do not fluoresce, but other embodiments, fluorescent paints or surfaces work. 
     With respect to the testing box  10  itself, without regard to the type of fixture or lamp associated with the testing box, in an exemplary embodiment, the testing box is configured to receive a sensor for detecting the light within the box.  FIG. 7  shows one exemplary embodiment of the testing box further illustrating a fiber-optic cable  23  entering the testing box connected to a sensor  22 . Inside the testing box  10  there can be a shielding baffle (not shown) installed on the wall that blocks the sensor&#39;s direct view of the luminaire as seen through the opening  11  in the testing box  10 . In some embodiments, the sensor  22  is merely an exposed end of a fiber optic cable  23 . In some embodiments, the sensor  22  is a spectrometer  41  (see  FIG. 12 ) at the opposite end of the fiber optic cable  23 . 
     Any type of sensor may be used, including: hand-held illuminance or luminance meter capable of measuring chromaticity, CCD camera, photodetector fitted with appropriate filters, or any other sensor known to persons of skill in the art. 
     Referring to  FIGS. 8A and 8B , side and front views, respectively, of a testing box are shown. In this exemplary embodiment, as shown in  FIG. 8A , the sensor  22  is exposed to as much of the interior surfaces of testing box  10  as possible without also exposing the sensor  22  to the opening  11 . As shown in  FIG. 8A , in an exemplary embodiment, the baffle  24  is sized so as to block any direct line of sight (represented by the dashed lines) between the unit under test (not shown) in the opening  11  and the sensor  22 . In the exemplary embodiment shown in  FIG. 8A , the baffle extends approximately one inch beyond the minimum size needed to block a direct line of sight. As one of skill in the art would understand, the precise sizing and shaping of the baffle can vary from application to application, depending on the size and shape of the unit under test, the testing box, the opening, and the positioning of the fiber optic cable. 
     Testing boxes of the present invention may take a variety of shapes. For example, the testing box may be: cube, rectangular, spherical, cylindrical, hemispherical, soccer ball shaped (truncated icosahedron), any enclosed polyhedron, or any other shape known to persons of skill. The testing box may be constructed of any suitable material, for example, plastic, aluminum, steel, wood, or any rigid opaque material. Depending on the shape and size of the lamp and/or fixture to be tested, the testing box may be customized to accommodate the lamp and/or fixture. Testing box shapes that are not sphere-shaped do not produce a full lumen reading, however, this lumen loss reading may be accounted for via the correlation explained below. No matter what the shape of the testing box, the sensor may be placed in the testing box relative to the opening so that there is not a direct line of sight between the opening and the sensor. A baffle or a plurality of baffles may be included inside the testing box as a barrier between the sensor and the opening to prevent a direct line of sight. 
     When measuring color temperature of the light output from the lamp (conventionally measured in degrees Kelvin), as well as the total light output (measured in lumens), conventionally, the output from an integrating sphere is provided to a spectrometer, which provides the color temperature to a computer. The computer can then determine where on the CIE (“International Commission on Illumination”) diagram the chromaticity of the output of a luminaire appears. The CIE diagram is shown in  FIG. 9 . The CIE diagram shown in  FIG. 9  provides a number of MacAdam ellipses, which define a region on the CIE diagram wherein light having a chromaticity falling anywhere within the ellipse would be generally indistinguishable to the human eye. The MacAdam ellipses shown in  FIG. 9  are further bounded by quadrangles. The quadrangles represent a range of chromaticity coordinates that, according to the American National Standards Institute (ANSI) can be legitimately characterized as having a given color temperature. By way of example, a lamp having an (x, y) chromaticity value of (0.48, 0.43) can be fairly characterized as having a color temperature of 2,700 Kelvin. As a further example, a lamp having an (x, y) chromaticity value of (0.44, 0.39) can also be fairly characterized as having a color temperature of 2,700 Kelvin. 
     While ANSI boundaries may be used to define a color boundary, it should be noted that any color boundary may be used as the specification criteria for end of line testing. For example, the boundary specification may be based on advertising requirements for lamps and/or light fixtures, applications for lamps and/or fixtures, such as indoor, outdoor, residential, industrial applications, type of luminaire, lamp and/or light fixture, validation of manufacturer lamps and/or light fixtures, special lighting requirements such as holiday lighting, and custom color requirements. 
     The integrating sphere properly equipped with a light measuring device is considered the gold standard in measuring chromaticity coordinates and light output to determine whether the output of a lamp falls within the proper quadrangle on the CIE diagram. When a spectrometer is connected to a testing box of the present invention, however, the measurements may differ. Accordingly, the present invention provides a method for correlating measurements taken in an integrating sphere to measurements taken in a testing box. By way of example, when a lamp is measured for chromaticity in an integrating sphere, the output may be represented as shown in  FIG. 10 .  FIG. 10  shows a graph wherein the x-axis is CIE x and the y-axis is CIE y. The ANSI boundary  30  for chromaticity lamp output, which is a quadrilateral bounded by dots in the graph, can fairly be characterized as having a color temperature of 3,500 degrees Kelvin. The chromaticity output  31  of a test lamp as measured in an integrating sphere is shown as an asterisk at coordinates (0.4125, 0.4009). As shown in  FIG. 10 , the chromaticity of the test lamp as measured by the integrating sphere clearly fits within the ANSI boundary  30 , and can fairly be characterized as having a color temperature of 3,500 degrees Kelvin. If testing was taking place with an integrating sphere, a computer could determine whether the results from the test fall within the ANSI boundary, and issue a corresponding pass or fail for the unit under test. 
     To correlate the testing results from an integrating sphere to the testing results in a testing box, a test lamp that has demonstrated the proper color temperature in an integrating sphere is then tested in the testing box.  FIG. 10  also shows the chromaticity output  32  of the same test lamp measured by a testing box according to an exemplary embodiment of the present invention, wherein the result is represented by “dot” at coordinates (0.4107, 0.3968). As shown in  FIG. 10 , the same test lamp produced slightly different chromaticity results when measured in the testing box compared to when measured by the integrating sphere. 
       FIG. 10  also illustrates how the results from a testing box can be correlated to the results from an integrating sphere. As can be seen, there is a linear relationship between chromaticity output  32  measured by the testing box compared to the chromaticity output  31  measured by the integrating sphere. Accordingly, the ANSI boundary  30  quadrilateral may be shifted similar to the linear relationship between chromaticity output measured  32  by the testing box compared to the chromaticity output  31  measured by the integrating sphere of obtain an end of line (EOL) shifted boundary  33 . A computer may then be programmed with the EOL shifted boundary  33 , wherein the quadrilateral is the shifted boundaries as determined by the difference between the chromaticity output  32  measured by the testing box compared to the chromaticity output  31  measured by the integrating sphere. Once the computer is programmed with the new boundaries, the testing box can be used in place of the integrating sphere in the manufacturing line. In an exemplary embodiment, a statistically significant number of test lamps are tested in the integrating sphere and the testing box, and an average (or other statistical correlation to derive a point from the results) is created to determine the appropriate distance to move or shift the quadrilateral boundary. 
     The boundaries illustrated in  FIG. 10  are defined by the following coordinates for an exemplary testing box correlation. 
     
       
         
               
             
               
               
               
               
             
           
               
                   
               
               
                 3500K BOUNDARY 
               
             
          
           
               
                   
                   
                 x 
                 y 
               
               
                   
               
               
                 ANSI BOUNDARY 
                   
                   
                   
               
               
                 Center Point 
                   
                 0.4073 
                 0.3917 
               
               
                 ANSI quadrangle 
                 (x1, y1)  
                 0.4299 
                 0.4165 
               
               
                   
                 (x2, y2)  
                 0.3996 
                 0.4015 
               
               
                   
                 (x3, y3)  
                 0.3889 
                 0.3690 
               
               
                   
                 (x4, y4)  
                 0.4147 
                 0.3814 
               
               
                 MEASURED POINTS 
                   
                   
                   
               
               
                 6″ Correlation Module Sphere 
                   
                 0.4125 
                 0.4009 
               
               
                 6″ Correlation Module EOL 
                   
                 0.4107 
                 0.3968 
               
               
                 Shifted Vector Difference 
                   
                 −0.0018 
                 −0.0041 
               
               
                 END OF LINE BOUNDARY 
                   
                   
                   
               
               
                 Center Point 
                   
                 0.4055 
                 0.3876 
               
               
                 SHIFTED quadrangle 
                 (x1, y1) 
                 0.4281 
                 0.4124 
               
               
                   
                 (x2, y2)  
                 0.3978 
                 0.3974 
               
               
                   
                 (x3, y3)  
                 0.3871 
                 0.3649 
               
               
                   
                 (x4, y4)  
                 0.4129 
                 0.3773 
               
               
                   
               
             
          
         
       
     
       FIG. 11  illustrates a graph for boundaries of another testing box correlation. As in the prior example, this example provides CIE color data for 3500K.  FIG. 11  shows a graph wherein the x-axis is CIE x and the y-axis is CIE y. The ANSI boundary  30  for chromaticity lamp output, which is a quadrilateral, can fairly be characterized as having a color temperature of 3,500 degrees Kelvin. The chromaticity outputs  31  of two different test lamps as measured in an integrating sphere are shown at approximate coordinates (0.419, 0.399) and (0.420, 0.401). As shown in  FIG. 11 , the chromaticity of the two test lamps as measured by the integrating sphere clearly fits within the ANSI boundary  30 , and can fairly be characterized as having a color temperature of 3,500 degrees Kelvin. To correlate the testing results from an integrating sphere to the testing results in a testing box, the two test lamps that demonstrated the proper color temperature in the integrating sphere are then tested in the testing box.  FIG. 11  also shows the chromaticity outputs  32  of the same two test lamps measured by a testing box, wherein the outputs are shown at approximate coordinates (0.421, 0.397) and (0.422, 0.398). Because both of the test lamps shifted similarly between the integrating sphere and the testing box, one may have greater confidence that the shift correlation is accurate. Based on the shift of the two test lamps, the correlated boundary  33  for the testing box is calculated and plotted on the graph. 
     It should be noted that the correlation shift illustrated in  FIG. 10  is different from the correlation shift illustrated in  FIG. 11 . This is because the correlation shift is unique to individual testing boxes. Different testing boxes were correlated, such that the correlation shifts were different. 
     According to embodiments of the invention, color characteristics are correlated. In this context, color characteristics may include color temperature and CIE chromaticity coordinates (from which color temperature may be calculated). 
     Further, it should be noted that there are several different “color space” diagrams, which are used by persons of skill in the art, in addition to the CIE (x, y) diagram. Different revisions of diagrams have been published, which are merely transformations of each other or different ways to assess color quality. For example, one may plot color in units of (x, y) or (u, v) or (u′, v′). The concept is the same as for the CIE (x, y) diagram but the data is plotted against a different scale on the axes. Any color space known to persons of skill in the art may be used with the present invention. For example, but not limited to, the CIE 1931 chromaticity coordinates and diagram. Color spaces include, but are not limited to, the CIE 1931 chromaticity diagram, the CIE 1964 chromaticity diagram, and the CIE 1976 chromaticity diagram. 
     There are several methods that can be used to determine whether a chromaticity output falls within a boundary. There are several methods that can be used to determine whether the chromaticity value (or any other light characteristic) falls within an allowable or specified range. One of skill in the art would understand that any suitable two-dimensional mathematical algorithm can be used to test whether a single point lies inside or outside an enclosed bounding polygon. For example, one of skill in the art would understand that a “winding number” algorithm can be used to determine whether a given point falls within an arbitrary polygon. Other algorithms, such as a “crossing number” algorithm can also be used. 
     A similar method can be used to correlate the quantity of light measured in the integrating sphere with the quantity of light measured in the testing box. For example, if a reference lamp is measured at 1000 lumens in the integrating sphere, but that same reference lamp measures 800 lumens in the testing box, then a relationship between the actual lumen output, as measured in the integrating sphere and the tested lumen output, as measured in the testing box of all subsequently manufactured lamps, can be shown as:
 
[Actual Lumen Output]=[Lumen Output Measured in Testing Box]×[1000/800 lumens]
 
In this regard, then, the actual lumen output of the lamp can be determined based on a measurement taken in the testing box. As with the chromaticity coordinates, in an exemplary embodiment, a statistically significant number of lamps may be measured in both the testing box and the integrating sphere to determine the proper correlation.
 
     As noted above, the testing box may take any shape. The shape and/or the number of sides of the testing box are accounted in the correlation. This procedure works uniquely for each geometry or test sample configuration. This ratio relationship between integrating sphere and test box must be established for each and every different geometry of product being tested. For example, measurements for a 6″ diameter recessed downlight are not the same as a 4″ diameter recessed downlight. Further, if the same 6″ downlight is used with different reflector inserts, it will also change the light measurements. The correlation is unique for even very subtle differences in sample geometry. 
     Once a correlation between integrating sphere measurements and testing box measurements has been determined for a given testing box and lighting fixture, the testing box can be placed in the production line. Importantly, this leaves the integrating sphere free to test other manufacturing lines, or advantageously, to identify correlations for other testing boxes and other fixtures. In this way, new manufacturing lines can be added without the significant expense involved in purchasing additional integrating spheres. 
     Referring to  FIG. 12 , a testing station is illustrated for measuring the color temperature of the light output from fixture lamp (expressed in degrees Kelvin) and the total light output from the fixture lamp (expressed in lumens) is illustrated. The system comprises a testing box  10 , wherein a fixture  15  may be positioned at an opening  11  of the testing box  10 . The testing box  10  has a light sensor  22  protruding through a side wall of the testing box  10 . In a simple form, the light sensor  22  may be an exposed end of a fiber optic cable. A spectrometer  41  is connected to the light sensor  22  via a fiber optic cable  23 . A power meter  40  is electrically connected to the current driver of the fixture  15  to measure the power being supplied to the lamp in the fixture  15 . A computer  42  is provided to receive inputs from the power meter  40  and the spectrometer  41 . A monitor  43  is connected to the computer  42  to provide the testing station technician feedback as to the results of the tests. The computer  42  also receives inputs from a bar code scanner  17 , wherein bar code labels may be used to identify individual fixtures being tested so that test results may be associated with light fixtures being tested. The end of line testing station may also be set up with conveyors or other devices to deliver and/or take away lamps or fixtures from the tray. Any systems known to persons of skill may be employed to speed the testing process and enable quicker flow of products through the station. 
     Referring to  FIG. 13 , a method for end of line testing of lamps and/or light fixtures is illustrated as a flow chart. First, a testing box is built to accommodate the particular type of lamp and/or fixture to be tested at the end of the production line. Second, a test lamp is measured for color in an integrating sphere. Third, a color boundary is generated from the measured color of the test lamp in the integrating sphere. Fourth, the test lamp is measured for color in the testing box. Next, the color boundary is shifted to a shifted test box color boundary, based on a correlation between the measured colors of the test lamp in the integrating sphere and the testing box. End of line test the lamps and/or light fixtures in the testing box. If the color of the lamp and/or light fixture, as measured in the testing box, is within the shifted test box color boundary, then PASS the lamp and/or light fixture and certify that it has the measured color. If the color of the lamp and/or light fixture, as measured in the testing box, is not within the shifted test box color boundary, then FAIL the lamp and/or light fixture. 
     Referring to  FIG. 14 , a method for end of line testing of lamps and/or light fixtures is illustrated as a flow chart, whereby actual lumen output is the testing criteria. First, a testing box is built to accommodate the particular type of lamp and/or fixture to be tested at the end of the production line. Second, the lumen output of a test lamp is measured in an integrating sphere. Third, the lumen output of a test lamp is measured in the testing box. Fourth, the lumen output of a subject lamp is measured in the testing box. Fifth, the actual lumen output of the subject lamp is determined by multiplying the measured lumen output of the subject lamp in the testing box by the measured lumen output of the test lamp in the integrating sphere and dividing by the measured lumen output of the test lamp in the testing box. If the determined actual lumen output of the subject lamp and/or light fixture, as measured in the testing box, is within specified lumen output range, then PASS the lamp and/or light fixture and certify that it has the specified lumen output. If the determined actual lumen output of the subject lamp and/or light fixture, as measured in the testing box, is not within the specified lumen output range, then FAIL the lamp and/or light fixture. 
     Although the disclosed embodiments are described in detail in the present disclosure, it should be understood that various changes, substitutions and alterations can be made to the embodiments without departing from their spirit and scope.