LED Color Tuning

Polar Ray Admin

The continuing advancements in solid state lighting (SSL) development are allowing for more precise control of the characteristics that LED luminaries are capable of. Beyond the most well-known characteristic of energy savings, there are many more features that are associated with the LED technology that make it a form of lighting that is unprecedented in the history of artificial lighting technology. One of the most interesting and applicable features is the ability to change the color of the light. The light color being the correlated color temperature (CCT) which indicates the relative color appearance of white light, from the lower values (about 2700K – the warm yellow appearance) to the higher values (in the 6000K range – the cool blue coloration). The color tuning ability of LED lighting, from a lower CCT to a higher CCT, is something that has seen some use in architectural lighting markets since shortly after the initial introduction of LED lighting. Today, the idea of color-tunable LED lighting is a budding and growing category of LED lighting technology. These adjustable color lights can offer potential benefits which could include mood and alertness enhancement, increased productivity, greater occupant satisfaction, and overall improved well-being. With all the potential benefits of such lighting, there is good reason to believe that there is a great market potential for color adjustable lighting.

There are compromises, limitations and other matters that accompany the color-tunable sector of LED lighting that must be worked out by the industry to conquer the challenges that need addressing so these systems can develop into the best possible products. The reporting of performance for these systems is much more involved than standard single color LED lighting, and because the number of possible procedures in creating color-tunable lighting products makes for a more difficult comparison among processes. Since there are no standard procedures for determining performance, it is difficult to compare and contrast systems. At this point in time there are basically three different approaches taken by manufacturers to obtain color tuning but it is theorized that in the end there will be one particular scheme which proves to be the most effective and can be used throughout the industry to standardize the process. One of the greatest reasons for standardization comes in the specification department; in today’s atmosphere, there are numerous confusing issues which create a number of challenges in specifying particular products that need to be addressed.

One of the methods of CCT adjustability is referred to as dim-to-warm, which is a technique which somewhat mimics the incandescent and halogen dimming performance which is generally designed to be a maximum CCT of 2700-3000K with the ability to be adjusted into the range of about 1800K (about the color of candlelight). This particular region of color is especially treasured in places such as residential spaces, restaurants, theatres, hotel lobbies, ballrooms and similar venues where thae lower CCT is pretty much a standard as a light the produces a relaxing atmosphere. One of the potential issues known in this system is that in many cases there is a desire to dim the lighting without changing the CCT, so that will have to be worked into the system as well. Some systems utilize two different colored LEDs to create the desired effect; white LEDs for the higher CCT along with amber LEDs to create the warmer colors. The problem with this sort of arrangement can occur at the lower end of the color regioin where the amber light can cause poor color rendering index (CRI) issues which can make skin tones and other object and room colors look quite bad. As suggested by numerous sources, the minimum CRI in any lighting system should be a rating of 80 or above.

Another method is referred to as white-tunable, tunable white or Kelvin changing. In this setup, the manufacturer utilizes two sets of phosphor-coated LEDs which are output controllable. One set of LEDs will be a warm-white color – around 2700K – and the second set will be in the cool-white range of 5000-6500K. With each set controlled so that by individually increasing and decreasing the output of the two different colors, white colors of varying CCT will be created across the possible range of the two sets of LEDs. These systems must utilize carefully selected colors of LEDs as the incorrect combinations can create poor coloring in the light which can produce pinkish and purplish colors as the light changes through CCT settings. There are also multi LED arrangements which use three or more LED colors to achieve a sliding scale of colors, and in doing so can more effectively avoid the off colors which can occur in two source systems.

A third system configuration, known as full-color-tunable, and going by numerous other different names (which, probably, also needs to be changed to one recognizable moniker) uses a minimum of three different color LED sets of primaries. These can be output adjusted to create a light mixture that is white, a tint of white, or a saturated hue. The colors of LEDs used in these systems can produce light in a narrow band and, thus, can produce the most effective color tuning systems. One potentially large problem with this system is that there can be numerous ways to create different colors from three or more different sources, but which one will produce the best color rendering can be an issue. There are also potential issues with over or under saturation of colors as well as other control and efficacy issues that need to be addressed in order to reach the expected potential.

There are potential issues that need to be overcome with all the systems before the expected results will be realized and the systems will create a sliding scale of light color temperature that will be balanced and produce true color rendering. The progress is impressive and even though the early color-tuning LED systems do a pretty nice job of producing lighting which is color adjustable, the advancement in the field is on track to produce systems which can produce different atmospheres within spaces by adjusting the CCT of the lighting system in a way which enhances the surroundings and creates a comfortably lit environment which can be changed as necessary.

As always, if you have questions in regard to any of your lighting projects, please feel free to call Polar-Ray at 303-494-5773 to speak with a lighting consultant. Thank you for perusing our web site.