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Future Lighting Solutions

LED Technologies which Promise Commercial Opportunity for Lighting OEMs in 2021

How technology is creating new solutions for infection control, more efficient street lighting and healthier indoor spaces

By Francois Mirand EMEA Technical Director, Future Lighting Solutions, a division of Future Electronics

The LED lighting industry has been an exciting field in which to work over the past 20 years because its technology develops at a rapid pace. This creates not only the opportunity to improve the design of existing types of fixtures, but also to create entirely new applications for lighting. Who imagined 20 years ago that the shape and illumination pattern of something as simple as a car’s indicator light could become an important part of the brand signature of a premium marque such as Audi? Or that the street scene in cities all around the world would be newly filled with colour at night thanks to LED streetlights?

The innovation continues: with the global deployment of coronavirus vaccines proceeding apace in 2021, lighting technology suppliers are primed to launch a blitz of new products on to a market which is ready to meet a burst of pent up demand. So which LED technologies are expected to enjoy fast growth in 2021?

New Appreciation of Hygiene and Disinfection

The hygiene lessons of the Sars-COV-2 pandemic are not going to be forgotten in a hurry. The increased attention paid in 2020 to disinfection and decontamination has helped to stifle the transmission of the coronavirus, of course, but has also contributed to lower rates of infection with influenza, the common cold and other diseases. And there is now a very broad public understanding that regular disinfection will help to stop the spread of any new strains or viruses which emerge in future.

New optoelectronics products have their part to play in the battle against transmission of infection: interest in the germicidal properties of Ultraviolet (UV) light is increasing rapidly. Happily, the development of LEDs in the UVC portion of the spectrum, which covers wavelengths between 100nm and 280nm, is set to reach a tipping point in 2021.

Established suppliers such as Nichia and Seoul Viosys are vying with newcomers such as Luminus Devices to increase efficiency, lower the cost-per-UVC photon, and scale up production capacity. Crucially, manufacturers are now producing UVC LED products with output power above 100mW. Luminus for example has released the XFM-5050, a four-chip package producing a nominal output of 240mW.

At the same time, the cost of UVC LED light has fallen below 20 cents per mW and is edging closer to 10 cents per mW, which is seen as the tipping point by many equipment manufacturers. Efficiency in mass production parts has jumped from around 1.5% to more than 3%. Experts foresee rapid progress towards 10% efficiency.

In parallel, manufacturers of optics for LEDs have qualified new materials and released dedicated products which are both efficient, and resist degradation by UVC light. The increased power and efficiency of UVC LED light sources is leading product manufacturers to explore applications for air and water purification – to date, UVC LEDs have been used primarily for surface disinfection. UVC LEDs are particularly suitable for disinfection of indoor air when placed at ceiling height (known as upper-room air disinfection): the very small light-emitting surface of a UVC LED enables tight beam control. For example, a Seoul Viosys linear UVC light module can be paired with the LEDiL VIOLET RS optic to make an ideal off-the-shelf light engine (see Figure 1a).

LEDiL VIOLET-12X1-RS combined with a linear UVC LED module such as the Seoul Viosys XMD-FBC-LLCA may be used in upper-room air disinfection applications.

Fig. 1a: the LEDiL VIOLET-12X1-RS combined with a linear UVC LED module such as the Seoul Viosys XMD-FBC-LLCA may be used in upper-room air disinfection applications. (Image credit: LEDiL)

LEDiL VIOLET-RS optic for UVC LED linear modules

Fig. 1b: the LEDiL VIOLET-RS optic for UVC LED linear modules. (Image credit: LEDiL)

Following the IES volumetric dosing guideline of 12mW/m3, such a UVC light engine would cover approximately 10m3, or 4m² in a room with a 2.5m high ceiling, burning around 10W of electrical power. The LED unit is itself much smaller than a mercury tube. What’s more the mercury tube requires a large reflector to shape its 360° irradiation to a narrow beam.

Compact and lightweight, the UVC LED unit can be added to existing lighting fixtures, or fully integrated into future designs, to add the value of indoor air disinfection to the standard visible illumination function, or to operate in stand-alone air disinfection mode.

The adoption of UVC LEDs in municipal water treatment works is also forecast to gather pace after the first installation in 2020. The use of UVC irradiation to eliminate microbial contamination from water supplies is well understood. Using LED technology, manufacturers can realise new, more compact reactor designs which fit in the limited available space in existing plants, greatly reducing or eliminating the cost of building work to create space for disinfection equipment. In addition, the use of LED technology entails lower maintenance cost and effort than conventional UVC emitters (see Figure 2).

The first UV LED-based water treatment units installed near Carlisle, UK

Fig. 2: The first UV LED-based water treatment units installed near Carlisle, UK. (Image credit: Typhon Treatment.)

Innovation in LED Formats for Streetlights

While development in the UVC LED field has centred on the fundamental performance of the emitter, in the LEDs used in streetlights, manufacturers are bringing their powers of innovation to packaging, production and reliability.

Until recently, streetlight designs were based on the use of single-chip, high-power LEDs. Now, however, the manufacturers of streetlights are overcoming their objections to the use of newer LED platforms: multi-chip high-power LEDs such as the popular 5050 package; and mid-power LEDs, generally in the standard 3030 format.

This move has been possible because LED manufacturers have improved the reliability of these newer products. In particular, sulfur resistance has been improved, and L90 projections can now exceed 100,000 hours. Lumileds is a good example of the progress that has been made: its LUXEON 5050 Square LED is a popular choice for streetlights. Its XR-5050 SQR modules are compliant with the Zhaga Book 15 footprint and meet the most stringent tender requirements (see Figure 3).

Lumileds’ XR-5050 SQR module

Fig. 3: Lumileds’ XR-5050 SQR module. (Image credit: Lumileds)

The benefits of using these newer LED types include:

  • Superior efficacy, especially at the lower CCT values specified by measures aimed at limiting light pollution
  • Greater design flexibility
  • Lower system cost

Innovation is also reshaping the market’s approach to control and networking of arrays of streetlights. Europe has been at the forefront of this move, leading the standardization of control interfaces for streetlights. Zhaga and DiiA have joined forces with the IES to back the D4i standard; and ANSI C136.41 receptacle-based hybrid architectures are to be added to the Zhaga Book 18 Ed. 3.0.

This is enabling streetlight manufacturers to develop future-proof designs under the Zhaga-D4i standard umbrella ready to support both local and remote control, as well as 5G deployment further in the future. The D4i roll-out is also finding support among driver manufacturers: Inventronics with its EUM series, for example, was the first to qualify IP67-rated drivers to the D4i standard.

Diverse Approaches to ‘Natural’ Lighting

Moving indoors, the lumen-per-Watt race attracts far less attention than before, and LED manufacturers now compete to introduce innovations which improve the quality of light. Color rendering is one important parameter of quality: mainstream LEDs today generally offer 80 CRI and 90 CRI variations. In the premium LED market, 95 CRI has become more common and several LED manufacturers now specify in addition an R9 value: Nichia has released COB LEDs which offer minimum Ra 95 and R9 80 values.

Uniformity is another challenge for manufacturers which seek to meet lighting designers’ strictest demands for quality of light. Here, Lumileds with its LUXEON Deep Dimming products and Nichia with its 757-MT are providing new solutions for luminaires implementing deep DC dimming or tunable white lighting.

Meanwhile, the jury is still out on the question of the best way to stimulate public appreciation of the concept of natural or ‘human-centric’ lighting (HCL). Scientific consensus about spectral effects on human health is similarly hard to find. Nevertheless, the choice of LED sources for HCL grows apace. It includes both full-spectrum LED sources such as the Seoul Semiconductor SunLike range, Nichia’s Optisolis™ LEDs or the Bridgelux Thrive™ family; and cyan-enhanced products such as Nichia’s Vitasolis™ or the Luminus Salud range.

Real-world deployments remain scarce, but 2021 is expected to see some growth in this field, sparked by a 2020 study by the Fraunhofer Institute for Building Physics on the perception of full-spectrum LEDs, which found support for the claims of advantages in HCL over conventional LED lighting.

One expression of HCL is circadian lighting, in which the colour temperature is adjusted throughout the day to match the natural spectral variation in sunlight, and to mimic the spectral characteristics of natural firelight at night. Bridgelux provides a way to ease the implementation of the tunable white systems required for circadian lighting with its Vesta® Flex drivers and Vesta Thrive LED modules. This turnkey solution includes full spectrum tunable white LED light sources, dual-channel drivers and control interfaces which support both standard 0-10V, DALI and Qualified Bluetooth® mesh systems, and proprietary control protocols.

Qualified Bluetooth mesh, also known as SIG mesh, has become the wireless control protocol of choice for indoor lighting, and has been adopted by important players in the industry. The standard has delivered on the promise of interoperability: compliant devices from different manufacturers can be commissioned using tools such as the Silvair platform to form a functional lighting control network.

The release of the Mesh Device Properties v2 specification in September 2020 has unlocked more IoT capabilities beyond simple lighting control, enabling detailed diagnostics and reporting of maintenance events. Companies such as Silvair are already integrating these new capabilities into their firmware and commissioning applications. We will see Silvair’s implementation of stand-alone scheduling, requiring no gateway, become available in the first half of 2021, an important move which will make it easier to design and deploy circadian lighting systems.

Technology Trends to Follow

Future Lighting Solutions can see today the evidence of rising demand for the technology developments described above. But looking further ahead, innovations already in the pipeline are set to excite further interest. In HCL, for instance, Nichia unveiled in December 2020 a phosphor-converted cyan LED-based Circadian Tune solution which should be released to the market during the summer of 2021.

In street lighting, the deployment of 5G mobile networks will have a profound impact. The massive Machine-Type Communication (mMTC) feature in 5G will enable new central monitoring capabilities encompassing municipal lighting. There is great promise in efforts to make streetlights the IoT hub of smart cities. Streetlight poles are also an ideal host for the 5G microcells required to provide dense network coverage in urban areas.

And the collaboration between the Bluetooth Special interest Group and the DiiA will undoubtedly fuel the adoption of both D4i and Bluetooth mesh in indoor lighting following the release of Zhaga Book 20.

The rate of innovation in LED technology, then, gives great cause for optimism as the world emerges from its Covid-induced slump, and the prospects appear particularly strong in UV LEDs, street lighting and HCL.