Articles & Interviews

LpR Article | Jul 04, 2016

An LED Solution for Historic Monumental Electric Chandeliers by Ramselaar Light Solutions

The Netherlands Institute for War Documentation (NIOD) is housed in a magnificent monumental late 19th century building at the Amsterdam Herengracht (the Netherlands). Recently, the unique brass chandeliers were provided with LED lamps, which were specially developed for this project by Ramselaar Light Solutions. Ron Ramselaar and M. Brouwers, advisor on behalf of the Government Buildings Agency (RGD), tell us about this extraordinary project. Read more »

LpR Article | Jul 04, 2016

Aspects of Light Quality in Solid State Lighting by OSRAM Opto Semiconductors

For ages the quality of light has been one of the biggest topics for luminaire manufacturers. But since the introduction of LEDs in general lighting the definition of light quality has got a new dimension. Pros and cons of LED lighting quality are often very controversial. Alexander Wilm, Application Engineering Manager of OSRAM Opto Semiconductors, presents facts about LED lighting quality that provide a sound basis for discussions. Read more »

Automatic Panel Level Transient Thermal Tester

LpR 67 Article, page 44:The thermal resistance junction in case is an important parameter for the reliability of LEDs because degradation of the LED is temperature driven. Simulation and testing has advanced over the past few years but transient thermal analysis (TTA), which is required to understand the thermal transfer path, is especially work and time consuming - and not automated. Gordon Elger, Professor for Electronic Manufacturing Technologies, Technische Hochschule Ingolstadt, and his co-authors, Maximilian Schmidt, Alexander Hans, and Dominik Müller, present and discuss an automatic panel level TTA tester. They explain the challenges and the solution and demonstrate the applicability of using LED test board-panels. Read more »

Avoiding Brightness and Color Mismatch with Proper RGB Gamut Calibration

For well over a decade, proponents of Solid-State Lighting (SSL) have been offering bullish forecasts concerning the adoption of LEDs for general and specialized lighting applications. Recent years have seen those rosy predictions come true, with LED lighting now almost completely dominating the market for new construction, retrofit, and many replacement lighting applications. For many of these applications accurate color calibration is required. Rood Bouten, CTO at Admesy, explains the reasons and how to perform a proper RGB gamut calibration. Read more »

Resources | LpR Article | Applications | Animal Farming | Mar 13, 2017

Bio-Effective Lighting for Humans, Livestock and Plants

Mood lighting is often misleadingly interpreted as HCL. But HCL is much more because it includes biologically effective light that is beneficial or dangerous, depending on the correct application. While the relevant parts of the radiation spectrum may differ, light is also biologically effective for plants and animals and it is used to achieve well-defined effects. Volker Neu, General Manager LED at Vossloh-Schwabe Lighting Solutions, presents examples, discusses similarities and differences between humans, animals and plants in respect to the relevant spectra, and scrutinizes possible consequences. Read more »

Blue Light Hazard - How Dangerous Is SSL Lighting?

Modern Solid State Lighting (SSL) technology has long since found its way into our normal working and living environments. In the early phases, consumers were most concerned with lifetime, pricing and light quality of the new LED-based light sources. Now they have become almost ubiquitous, a focus has been placed on safety. At the recent Light+Building exhibition topics such as photobiological safety and blue light hazard (BLH) were highly ranked among both visitors and exhibitors. Read more »

Bluetooth Mesh Protocol as Applied to Lighting

Little more than one year ago, Bluetooth SIG released the Bluetooth Mesh standardization. Meanwhile, it has become widely adopted and is also one of the favorite systems for lighting controls. Russ Sharer, Vice President of Global Marketing and Business Development for Fulham, starts with an explanation of the Bluetooth Mesh protocol as applied to lighting control and defining its key elements. In a second portion of the article, he answers questions that lighting control evaluators could be asking their vendor. Read more »

LpR Article | Jun 07, 2016

Boost-Buck LED Driver Topology for Low Input and Output Ripple for Low EMI by Linear Technology

Many automotive LED driver circuits require constant-current DC/DC converter topologies that can both step-up and step-down the input-to-output voltage. Out of the commonly used step-up and step-down topologies, those that produce low EMI are the most desirable. Keith Szolusha, applications engineering section leader with Linear Technology, proposes a new boost-buck (boost-then-buck-mode) floating output LED driver to satisfy these requirements. Read more »

Health + Environment | LpR Article | Sep 06, 2016

Botanical Light Pollution - Red is the New Blue

In the beginning, the industry argued that LED lighting could help reduce light pollution. Meanwhile, various organizations claim the opposite effect is true and often sight light color as an issue. The opinions of different groups are frequently quite the contrary to those of other groups. Ian Ashdown, FIES Chief Scientist at byHeart Consultants & Lighting Analysts, demonstrates and discusses the negative effects of light pollution through LED lights and how different light sources affect vegetation. Read more »

Brave New World and the Dualism of Light(ing)

The lighting business has been quite predictable over a long period of time. Technical changes were introduced slowly, dominated by a handful of leading companies, and mostly due to new, but not disruptive light sources. The life of engineers was mainly determined by a manageable number of parameters: Lighting requirements, light source parameters, costs, product dimensions, and the odd, required feature. Read more »

Resources | LpR Article | Commentary | Trends | Jan 15, 2018

Can You Show Me the Next S-Curve, Please?

The evolution of technologies is often described using the “S-curve” model. In the early stage, in the first phase of its life cycle, technology is mainly driven by fundamental research. Only a few players are active at that time and innovation steps are quite large. In the second phase, early adopters start to develop products and bring them to market. This phase is characterized by huge investments. In the third phase, more and more players enter the technology field, competition becomes important and development speed of the technology decreases. In the last phase, the technology is mature, (nearly) everybody can use it, there are fewer margins and the technology should be replaced by a new one. Many of the SSL technologies have meanwhile reached maturity. Where are the upcoming technologies, what will be the next S-curve? Looking at technology discussions and lectures at LpS 2017 I tried to find answers to these questions. Read more »

Research Reports | Smart Lighting + IoT | Resources | LpR Article | Oct 19, 2018

Challenges of the Integration of Lighting Systems and Components in IoT

LpR 68 Article, page 50: Following the rapid penetration of LEDs, lighting is now becoming integrated into the Internet of Things. Over the past three years a consortium of leading European companies worked on the OpenAIS project, which was partly funded by the EU within the Horizon 2020 program, and now showing the results working at a full size demonstrator. In this follow up article to the introduction article of LpR 67, Ben Pronk, System Architect at Signify, and Stefan Verbrugh, Project Manager at Signify and Work Package leader in OpenAIS give deeper insight into the project. They explain the lighting specific challenges, describe the generic challenges for IP controlled lighting and present the approach to these challenges. They conclude by summarizing the findings from the pilot. Read more »

Resources | LpR Article | Research | Medical | Sep 12, 2017

Challenges when Designing LED-Based Illumination Systems in Medical Applications and Diagnostics

LEDs have become indispensable in medical technology and dentistry. But the requirements placed on these lighting products are very high: Minimized size, high, application specific color rendering index, efficient temperature management, usability and excellent disinfection opportunities are all extremely important. Prof. Paola Belloni from the Steinbeis Transfer Center Illumination Optics and Lighting Engineering and Furtwangen University, and Alexander Gärtner from the Faculty of Mechanical and Medical Engineering of the Furtwangen University discuss the requirements for different applications such as endoscopy, surgeries, dental devices, and photodynamic therapy. Further topics are the development of a self-disinfecting operation interface with edge-lit UV-A LEDs, and a new optimization approach, taking into account the reflection and absorption properties of human tissues. Read more »

LpR Article | Jul 01, 2016

Choosing the Appropriate Heatsink for an Application by Fischer Elektronik

Next to vibrations and moisture, temperature-related stress on electronic semiconductor elements is the most common cause of failure for electronic components and devices. Effective thermal management is obligatory to ensure durability, reliability and performance. Jürgen Harpain, Manager of Development at Fischer Elektronik explains how different types of heatsinks provide excellent solutions and which one is the appropriate solution for a given application. Read more »

CIE Calls for Focused Research Efforts to Support Healthful Lighting Recommendations

Not so long ago, vision scientists thought that light detection - photoreception - was exclusively performed by rod and cone cells in the retina. Photobiologists, however, conclusively demonstrated otherwise with the identification of the intrinsically photoreceptive retinal ganglion cells (ipRGCs) [1]. Whereas rods and cones detect pattern and color, and send this information to the visual cortex, ipRGCs (of which we are learning there are several subtypes) detect irradiance, and route their information to many brain structures. The most thoroughly studied of these is the suprachiasmatic nucleus of the hypothalamus, location of the central circadian clock, where the light and dark signals trigger the offset and onset of production of the hormone melatonin. As shown in figure 1, however, ipRGCs also project to other structures, about which, as yet, we have little information. Read more »

CIE Fosters Co-Ordination of Global Research and Standardization on Temporal Light Modulation

Dr. Jennifer Veitch, recently convened the CIE Stakeholder Workshop for Temporal Light Modulation Standards for Lighting Systems. Below is the exclusive report she provided on the workshop findings and the attitude of the CIE towards this important issue. Read more »

CIE Research Strategy on Defining New Calibration Sources and Illuminants

In photometry and radiometry, traceability of measurements requires appropriate calibration sources and transfer detectors. A major challenge is the technological revolution of lighting products towards LED lighting and the ban of incandescent lamps. This raises concern about the availability of incandescent photometric standard lamps in the future while the prices of such standard lamps are already increasing. In addition, calibration conditions should ideally be chosen to be as close as possible to the measurement conditions. Furthermore, the number of LED lighting measurements in laboratories and in the field has significantly increased, while the calibration of photometers is still done using incandescentbased standards. Therefore, it is important to investigate the pros and cons of replacement of conventional standard lamps with new solid-state technology. Peter Blattner and Tony Bergen, Division 2 Director and Secretary respectively, explain how CIE has defined the research topic “New Calibration Sources and Illuminants for Photometry, Colorimetry, and Radiometry” to address these concerns. Read more »

Circadian-Friendly Light Emitters: From CCT-Tuning to Blue-Free Technology

Common levels of blue radiation are sufficient to disrupt the circadian cycle, calling for blue-depleted emitters in the evening. Most current solutions employ low-CCT and suffer from poor light quality. Aurelien David, chief scientist at Soraa explains the melanopic lumen and its possible sources of inaccuracy related to the uncertainty in assessing the circadian action spectrum. In addition, he also discusses the concept of a blue-free emitter with minimal melanopic lumen at very low CCT and how such a spectrum providing a good light quality can be optimized. Read more »

Color Reproduction and Measurement of 3D Objects

CIE Division 8 Image Technology is responsible for the study of the optical, visual and metrological aspects of the communication, processing, and reproduction of images, using all types of analogue and digital imaging devices, storage media, and imaging media. The Division is continually working on recommendations to improve color image reproduction techniques, including, for example, colorappearance models, color-difference evaluation and gamut-mapping algorithms. Current technology is able to transform color images from one digital medium to another, under various viewing conditions, while maintaining the appearance of each color in the image. This process has been applied in the graphic arts industry with great success. According to Kaida Xiao, Chair of CIE's Division 8 TC 8-17, the CIE standard observer and psychophysical data for color-appearance and color-difference modelling were developed using flat, 2D color samples. He explains that to meet the increasing requirements for color image reproduction for 3D objects, new research and recommendations are highly desired. Read more »

Comparing New Dielectric Materials for Chip-on-Board LED Packages

Thermal management is still one of the most challenging issues in solid state lighting. With the increased application of COB LED technology, the portion of the dielectric material on the overall thermal resistance has become an important topic. Different solutions and new materials have been proposed over the last few years. Hui Zhang, Max Wagner, and Prof. Tran Quoc Khanh from the Laboratory of Lighting Technology at the Technische Universität Darmstadt compared different materials and present the results of their extensive research. Read more »

LpR Article | Jun 20, 2016

Concept of a Time-Proven LED Luminaire Design and Manufacturing Process by Lumitec Lighting

While doing successful business has always been a tough job, it has become even tougher with the introduction of solid-state technology into the lighting industry. Besides high quality criteria, time to market has become a crucial success factor. Innovative processes and tools and, last but not least, a talented and inspired team are necessary. Angela Betancourt presents an approved process used by Lumitec Lighting. Read more »

LpR Article | Technologies | Aug 11, 2016

Concepts to Overcome Lifetime Issues of LED Drivers

Lighting technology has changed significantly in recent years after a century of little to modest advancements. LED luminaires offer advancement in lower power consumption and expected life. Maggie Nadjmi, EE Product Manager at SL Power Electronics, explains why this new technology will probably not meet the life and reliability expectations if no attention is paid to the drivers and power supplies used to power LEDs. She discusses the main components affecting lifetime and how to eliminate them or design a product to still achieve the desired lifetime. Read more »

LpR Article | Jun 28, 2016

Contactless LED Technology

While Contactless power distribution using electromagnetic induction technology is not new, it is rarely used in an LED illumination system. Alain Guimont, an IES member and Product Specialist at HEICO lighting™, one of the few companies that designs products based on this type of an approach, explains how it works and discusses the advantages of this technology. Read more »

LpR Article | Technologies | Jun 03, 2016

Cost and Performance Optimization of Thermal Management Solution for High Power LEDs by Cambridge Nanotherm

The LED industry has a challenge. General lighting requires very bright LEDs that can replace incandescent and halogen lights. Manufacturers need efficacy, cost and manufacturability to be “just right” but most leading solutions, especially in thermal management, are short of the mark. Giles Humpston, applications engineer, Cambridge Nanotherm, discusses ways to combine performance with reasonable costs and good manufacturability. Read more »

LpR Article | Jun 20, 2016

Cost Saving Potential with Automation and Well Designed Processes by BJB GmbH

The manufacturing of modern LED luminaires and conventional fixtures has some similarities as well as some distinct differences that result in added challenges. Automation, in combination with a well-conceived product design and process combined with well-matched components, allows for economical manufacturing without compromising production quality and, consequently, reliable, high performance, and high quality luminaires. Olaf Baumeister, Head of Product Development and BJB-Automation at BJB GmbH, explains and discusses technical challenges, successful concepts and solutions. Read more »

LpR Article | Technologies | May 24, 2016

Create Colorful and Bright LED Light with an LED Matrix Dimmer by Linear Technology

RGB LEDs are quite common and used in many applications today. More advanced multi-color solutions like RGBW, RGBA or RGBWA offer huge advantages over RGB solutions, but several aspects are more complicated. Keith Szolusha, applications engineering section leader for power products at Linear Technology explains the advantages of RGBW systems, how they work, how to set up such systems, and how to drive them correctly using Linear Technology’s LT3965 8-switch LED matrix dimmer in combination with the LT3952 boost-buck LED driver as an example. Read more »

LpR Article | Jul 04, 2016

DC-Grids - Challenges and Chances for LED Lighting by the Fraunhofer Institute and LED professional

At the beginning of November many important aspects of DC Grids were discussed at the Fraunhofer Institute for Integrated Systems and Device Technology in Erlangen at the European Center for Power Electronics (ECPE) conference. Besides fundamental issues, very specific ones like how the introduction of DC Grids affects lighting technologies and especially LED lighting were part of the program. Below, Arno Grabher-Meyer from LED professional gives a summary of the speeches and expert discussions and gives us an idea of what the key ideas could mean to the LED lighting community. Read more »

LpR Article | Jun 20, 2016

Development of a Workflow for Colored Ray Data by TechnoTeam Bildverarbeitung GmbH

The importance of white LEDs has risen continuously over the past years. In many cases, disturbing color fringes appear on white LEDs with a blue chip and a yellow phosphor. To avoid this, different distribution of the blue and the yellow light has to be described for simulation. Therefore, colored ray files are necessary. Nicole Stubenrauch, Development Engineer at TechnoTeam Bildverarbeitung GmbH, explains a workflow and method for creating colored ray files. Read more »

LpR Article | Jul 04, 2016

Development Process for a Metal-Halide Replacement LED Module by Neonlite International Ltd.

Seen for the first time at this year’s Light + Building, the TECOH® MHx, has provided specifiers and designers with a viable LED metal halide alternative. Talking about the issues surrounding such a development, Fred Bass, Managing Director of Neonlite International Ltd., the brand owner of MEGAMAN, shows how the module series has been developed and highlights its potential for metal halide replacement moving forward. Read more »

Research | LpR Article

Direct Current (DC) Supply Grids for LED Lighting

Since many alternative energy sources as well as electronics and controls technologies are based on DC current, DC grids have been investigated more intensely in the last decade. DC grids with a centralized AC/DC conversion have proven to be advantageous in server farms. While LED lighting is also a DC current related technology, an obvious choice would be to use DC grids for them. Prof. Eberhard Waffenschmidt from the Cologne University of Applied Science in conjunction with Philips Research presents the results of an office building DC lamp system installation with photovoltaic (PV) support. Read more »