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Adjusting the tone of white light is certainly one of the latest innovations in the lighting industry. For some time, manufacturers of LED devices have being taking seriously the results of the research into the photobiological effects of artificial lighting. More knowledge of how the human body works combine with high-tech developments through the innovative use of LED artificial lighting.

Mixing of colour

A Tunable White luminaire is developed using white LED lights in hot and cold tones. It is possible by controlling the power supply for individual LED channels to mix the luminous flux and obtain a projection that covers the entire spectrum of white tones. From the warmest (3,000 Kelvin) to the coldest (6,000 Kelvin).

Tunable White circuit with side-by-side LED strips

Tunable White circuit with combined LED strips

Basic dual circuit systems

The simplest systems use LED combined strips. One strip emits warm white light at a temperature of around 3,000 Kelvin, while the other emits cold white light at around 6,000 Kelvin. Their most common application is generally inside aluminium profiles equipped with an opal diffuser that mixes colour as light passes through it. It is definitely a very simple solution, but it only meets basic needs and allows few options.

 

 

Multi-chip versions
multi-chip LED Tunable White circuit

multi-chip LED Tunable White circuit

The most advanced Tunable White products use multi-chip technology, where LEDs of both colour temperatures are combined in the same module. Different coloured LEDs (warm white and cold white) are supplied with power of varying degrees, depending on the desired colour temperature.
Tunable White multi-chip luminaires undoubtedly provide superior light performance and more colour control than dual-circuit systems.
The small size of each LED also makes it possible to manufacture very small luminaires. Spotlights and small panels are now available that use the same technology as professional linear systems.

 

 

 

Yet this is not enough and there are other parameters to consider, such as the range of colour temperature offered and the colour rendering.

 

 

Not all Tunable White system are the same
Example of a white range of white light shades.

Example of full range of tones of white light.

A Tunable White luminaire can be considered as offering a colour temperature adjustment of at least from 3,000 to 5,000-6,000 Kelvin.

The user should pay close attention to the temperature range offered when choosing a Tunable White luminaire. While some systems offer a wide range of white tones covering the entire natural circadian cycle, others have a more limited range and some are even limited to a range of 3000 to 4000 Kelvin, which should only be considered as a decorative option.

Colour rendering
The best colour rendering makes colors appear more brilliant and closer to real.

Optimal colour rendering makes the colour of objects brighter and more representative of reality.

All lighting devices, including LEDs, offer different nuances in terms of the way white light reproduces the colours of surfaces and illuminated objects. However, irrespective of the light source, a good level of colour rendering can be expected from any lighting product, including Tunable White luminaires. Nevertheless, it is not always clear from reading the manufacturer’s data how well a Tunable White luminaire will perform in terms of colour rendering.

Generally speaking, the better the system of mixing white tones and the greater the range, the better the colour rendering on the entire colour adjustment spectrum.

It should be noted that the cheapest products provide good colour rendering only at the extremes of the adjustment range, where the light is completely warm or completely cold. However, there is no certainty that the mixed light will be as chromatically high-performing.

 

 

The control systems of Tunable White devices
LED Tunable White spotlight with dynamic control system.

LED Tunable White spotlight with dynamic control system.

Each Tunable White LED lighting device requires a system for controlling and adjusting the light temperature. Some systems allow static selection (three fixed colour temperatures), others dynamic selection (free choice of colour temperature). Some luminaires have an integrated system and can seem simple to install, but we recommend opting for Tunable White multiple adjustment systems, which are capable of managing multiple Tunable White LED luminaires with just one adjustment system.

In applications for domestic use, adjusting the white tone of service luminaires, such as in the case of lights under kitchen wall units, is much more practical when performed simultaneously on all appliances, rather than separately on each one. This prevents the problem of not being able to exactly match the same white tone.

 

Tunable White luminaire systems deserve a more detailed write-up, which will soon be on this blog.

 

 

A quick check-list for your Tunable White LED project.

1. What colour temperature range do you want to regulate (values can range from 3000 to 6000 Kelvin)?

2. Does your favourite product ensure a high level of performance across the entire range of adjustment?

3. Have you considered which temperature control system is most appropriate for your needs? Do you need a mixed system or only a fixed selection?

 

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