Generally, people expect two light sources with the same rated color appearance to appear identical when installed in their homes and businesses. Obvious variation often leads to dissatisfaction, complaints and product returns. To avoid these issues, it is important that light sources have sufficient chromatic consistency to ensure color matching for most people. Currently, the lighting industry relies on binning for correlated color temperature (CCT) and Duv to address this issue.
Due to the construction process of typical LEDs, there is some level of variation in the color of light being produced by each emitter. To limit the difference in appearance of the light being produced, fixture manufacturers will select LED emitters that produce light within a certain range of chromaticity, a process known as “binning.” However, there is a lack of data on what level of variation in light color is visible to most people. This makes it difficult to know with certainty that the final fixture will achieve the chromatic uniformity goals.
These issues and others formed the basis for a multi-year research program conducted by the California Lighting Technology Center, with support from the California Energy Commission, aimed at improving the adoption of energy-efficient LED lighting products. This article presents results from one piece of this work focused on identifying the level of chromatic variation that avoids perceptible levels of color difference among today’s LED light sources.