Jan 12, 2021

Rethinking tunable white lighting for mainstream, volume products

Category: Illumination

Conventional two- or three-channel approaches to color tuning are complex and expensive. LUXEON Fusion produces better performance with fewer LEDs at lower system cost.

The implementation of tunable white LED lighting appears to offer great scope to lighting manufacturers to differentiate their products, and to lighting designers and specifiers to offer a new, more attractive, healthier or more immersive user experience.

Successful implementations of color tuning enable restaurants and bars to enrich an intimate ambience with dim-to-warm lighting control. Offices, schools and colleges can tune the color temperature to stimulate activity or induce a calm, restful vibe at different times of day with dynamic white color tuning. And retail stores can heighten the appeal of merchandise or make a powerful brand statement with precise color-on-demand control which hits a unique color point or saturates a specific tint.

These are ways in which color tuning can dramatically enhance the emotional impact, and the value, of lighting – but the unfortunate truth is that the industry has yet to fully embrace the potential. Lumileds’ consultations with customers tell us that this is for two key reasons: color tuning has been too difficult to implement; and the costs of implementing tunable white functionality have been too high, calling for many more LEDs and producing much lower efficacy and inferior performance than standard single-color static white fixtures.

These are the problems solved by the LUXEON Fusion product, the result of innovation and new thinking in LED system engineering by Lumileds.

The Conventional: Higher cost, more complex, performs worse

The conventional technique for implementing color-tunable white lighting is to mix the light from two primary sources at two different CCT values. This approach inherently compromises performance: over the tunable range, the maximum achievable flux will be highest in the middle of the range, when both sets of LEDs are operating at or close to full power. And it will be lowest at either end of the range, when only one set of LEDs is in use.

Some complex engineering workarounds can be applied to minimize the visible impact of the variation in flux, but these measures can themselves cause associated problems. For instance, the LEDs might be driven at a higher current at the ends of the range than at the middle, yet this itself can cause a color shift that makes it hard to achieve a consistent color output across units and across operating conditions. With a multi-CCT color points are off and brightness response is not as expected.

The drawbacks with conventional two-channel implementations are not limited to performance. Luminaire manufacturers’ experience is that any color-tuning implementation is different from every other one and requires a different mix of carefully selected and binned LEDs. Across a portfolio of tunable white products, manufacturers find that in many cases they must stock thousands of different SKUs, greatly increasing inventory complexity, cost and management overhead.

A single part for all tunable white luminaires

LUXEON Fusion, which stems from a complete re-thinking of the approach to tunable white lighting, provides the industry’s first solution that opens color tuning for mass adoption in volume applications. The LUXEON Fusion product enables configurable light engines which perform consistently   across families of luminaire products, including spotlights, downlights and linear fixtures. It supports color tuning in:

  • Dim-to-warm systems dimming down to 1800K
  • Dynamic white lighting systems, including human-centric lighting. LUXEON Fusion supports tuning over a very wide range of CCT values from 1800K to more than 10000K, while achieving a CRI of >90 over 95% of this color range.
  • Color-on-demand, providing precise color temperature tracking on the black body curve to within 0.001 Duv, or any specific color point above or below the black body curve

Lumileds’ breakthrough with its LUXEON Fusion product results from the use of three precisely characterized, phosphor-converted LEDs at specific color points. This radically different approach to color tuning means that maximum flux, efficacy and color rendering are highly consistent across the CCT range:

There is often as much as a 50% system efficiency penalty with multi-CCT solutions. System efficiency with a LUXEON Fusion solution is comparable to that of a ‘standard’ white solution and eliminates unnecessary losses. Fixtures can achieve consistent light output without color shift problems using between 30% and 50% fewer LEDs, reducing system cost and size.

Fully configurable, the LUXEON Fusion product’s color point can be set at the factory, at the time of installation or after installation. It is compatible with any digital or analog control technology and can be used with a standard single-channel LED driver as well as with more sophisticated multi-channel drivers. Integration with third-party control technology systems such as Summa from Summa Systems is already helping to accelerate adoption.

Color tuning now ready for the mainstream

With the development of LUXEON Fusion, Lumileds has simplified the fixture manufacturer’s design of dim-to-warm and tunable white, and dynamic or custom color point products with a single technical approach. This eliminates complexity and the cost of inventory management and production associated with the conventional two- or three-CCT approaches to tunable white lighting.

Further, the performance, efficiency and quality of light of tunable white luminaires based on LUXEON Fusion are far superior.

In fact, the difference in efficacy of a LUXEON Fusion-based system from that of a static white lighting fixture is minimal. Perhaps this will encourage manufacturers to think not ‘Why should we implement tunable white lighting?’, but rather, ‘Why wouldn’t we?’