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TECH-TALKS
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Juergen Honold – Seaborough

At LpS 2019, Mr. Honold held an interesting talk about photobiomodulation. For all those that don't know what photobiomodulation and its value are, we admit that before the Tech-Talk, we weren't sure, ourselves. LED professional talked about the company, how and why the focus was on this topic and what it is all about. An interesting aspect was the approach of adding the required amount of NIR to the visible spectrum while just using 5% more energy for a beneficial effect on human physiology.

LpS Best Papers

Best Papers @ LpS 2019: Challenges for Measuring Multichip LED Light Engines for Interior Lighting Applications

As LED systems have been evolving in many niche applications, scientists and engineers are constantly looking for ways to reduce heat, improve performance and to get reliable data. Accurate thermal characterization of LEDs is crucial to satisfy these efforts. This study focused on the design and manufacturing of a thermally improved and fully operational rapid temperature controllable chamber in which calibration and test phases of junction temperature measurements are sensitively conducted under low deviation.

Technologies
Compact LED drivers

Designing an Invisible Driver for High-End Track Lights

The historical evolution of light control by users started with a mechanical switch, followed by potentiometer and dimming, touch panels and touch screens, gesture and movement detection control, and ending today with voice. The latter are mostly online speaker independants like Alexa, Google Home and Siri. But there are privacy and security concerns. The article describes a speaker independent offline voice controls system, explains the technology and discusses pros and cons.

Technologies
LED drivers, efficiency

A Simple Method to Increase Efficiency and Reduce the Cost of High Light-Quality LED Drivers

Most high-quality LED drivers consist of a PFC-flyback converter in the first stage followed by a buck in the second stage. Both of the stages can be optimized for very high efficiency but nevertheless, the over-all efficiency doesn't reach the desired level. This is especially true for window drivers that can operate with LED engines in a wide range of current and power. The authors propose a simple method to increase the efficiency of such drivers with virtually no effort. Even better, the method allows the use of smaller inductors in the buck stage, leading to lower cost and potentially smaller size.

Technologies
CCT tuning, LEDs, 

A New Method to Tune An LED Spectrum

Spectral tunable LED is not novel and different principles for different applications can be found on the market. However, following the black body line, or satisfying the requirements on HCL while being efficient is not trivial. The author proposes a new method to separates different but necessary parts from a full white light spectrum into individual channels or packages and adjusting each channel by an electrical circuit. The method promises advantages to match circadian rhythms better due to its relatively higher involvement of the melanopic sensitivity, while the broader spectra avoid dominant peaks especially of the blue light.

Applications
LEDs, CSP

How to Implement the Latest LED Technology for a Successful Application

The pressure for LED manufacturers to produce cheaper, more efficient and more reliable products has dramatically increased and puts pressure on their R&D teams to bring new solutions to the table from the chip to the package. But new solutions like CSP or Wicop without package are not catching on as expected because the ecosystem for production has not adapted for these latest semiconductor developments. The article explains why, discusses opportunities for speeding up transition, and gives examples.

Standardization
Flicker

New Directive in Europe: Flicker of LED Lighting Comes to an End

Over the past 10 years LED lighting has gained in importance. It has also been noticed that the alternating proportion of LED light can be very high compared to incandescent lamps. Many institutions from all over the world have thought about algorithms to measure and evaluate light modulation, taking into account the effect it has on humans. In the meantime, directives have been established in the USA and Europe. But do the directives really have a positive effect on the health of humans and other beings? This article provides insight into this question

Standardization
Glare, discomfort

Discomfort Caused by Glare from Luminaires with a Non-Uniform Source Luminance

Glare and the resulting discomfort are a persistent issue in lighting that has become even bigger with the introduction of LEDs as a light source. While the UGR method is well established, there have been serious discussions about whether or not it is appropriate for SSL. The limitations of the UGR method need to be understood. The article deals with these limitations and consequently describes update research and how to apply the identified correction measures.

Special Topic - Health & Well-Being
PC-converted white LED

Adopting a LED More Suited to Circadian Entrainment

Since the introduction of LED lights, a lot has been said about risks of blue light for ocular health on the one hand, and the opportunity of circadian entrainment, on the other hand. While a controversial discussion on the first topic is ongoing, the second topic is well accepted. To solve both issues, the author of the article proposes the application of 465-470nm pumped phosphor converted white LEDs with a content of 86% - 92% blue-turquoise light and 8% - 14% blue-violet light. He proves the benefit of regulating the circadian entrainment more efficiently, maintaining a high typical efficacy of 150lm/W and good color rendering of CRI 80+ ideally supporting the WELL Building Standard