LpR Articles

LED professional Review (LpR) - Articles

Resources | LpR Article | Research | Environment | Mar 26, 2019

When Nights Are No Longer Dark: Effects of Artificial Light at Night on Agroecosystems

In recent decades, artificial lighting has become an integral part of the modern world. While the use of artificial light at night (ALAN) greatly benefits people, it often has unintended, negative consequences for wildlife and ecosystems. In particular, the increasing use of LED lighting raises ecological concerns due to its high content of blue light, to which many organisms are sensitive. Dr. Maja Grubisic, Researcher at the Leibniz-Institute and Guest Lecturer at Free University Berlin discusses how ALAN can directly and indirectly influence agroecosystems, with potential consequences for food production and biodiversity. Given the current lack of integrative studies on this important topic, the better understanding of effects of ALAN in agroecosystems is urgently needed. Read more »

Resources | LpR Article | Research | Environment | Mar 26, 2019

Hazard or Hope? LEDs and Wildlife

LpR 70 Article, page 52: The introduction and widespread uptake of LEDs as outdoor lighting has caused no small amount of concern amongst conservation biologists. The prevailing impression that LEDs are always blue-white is well founded as adoption of LEDs for streetlights were invariably high color temperatures and with the deterioration of phosphors the blue wavelengths penetrated even more. But LEDs do have characteristics that differentiate them from other light sources and may allow for the reduction of environmental effects of lighting on species and habitats: direction, duration, intensity, and spectrum. Travis Longcore, Assistant Professor at the University of Southern California's School of Architecture, sheds light on all these aspects. Read more »

Lighting and Emergency Dept. Clinician Wellness and Performance Improvement

LpR 70 Article, page 38: Short wavelength ("blue") light is known for its strong impact on humans covering "visual" function, wellness and performance of humans. Lighting has been recognized to have an effect on clinician wellness and performance as well as the occurence of medical errors. In a pilot study, Octavio L. Perez, Ph.D, WELL Accredited Professional and Adjunct Researcher at the Department of Population Health Science and Policy, and his team of scientists and physicians, Christopher Strother, Richard Vincent, Barbara Rabin and Harold S. Kaplan, from the Mount Sinai Hospital, New York, systematically investigated if and how a radically new lighting concept could improve wellness and performance in an emergency department. Read more »

Resources | LpR Article | Technologies | Thermal Management | Feb 01, 2019

Materials, Manufacturing and Technologies for Designing Passive Cooling Devices

Until recently, incandescent bulbs and fluorescent lights were the dominant light sources. Today it’s the energy efficient, durable and, in the meantime, cost effective, LED. But to achieve these attributes appropriate cooling is still necessary and due to progress over the last few years the need for active cooling solutions is limited to a few high power applications as long as the material and technology is carefully chosen. John Broadbent, Managing Director at Columbia-Staver Ltd., describes the different technologies and materials and gives practical advice on how to find the right solution for an application. Read more »

Resources | LpR Article | Engineering | Optics | Jan 31, 2019

Additive Optics Design and Fabrication for Smart Lighting Systems and Tailored Project Solutions

Since its initial invention back in 2009, printed optics has come a long way in the lighting industry. Additive optics fabrication is a future proof methodology of rapid prototyping custom LED optics by means of digital manufacturing technologies. Marco de Visser, Luximprint’s Director of Marketing & Sales, breaks down the technology and explains how its features add value to the design and manufacture of smart lighting applications. From one of Luximprint’s preferred optical design partners Physionary, Ramon van der Hilst, Founder and Business Development Manager, and Suresh Christopher, inventor of the state-of-the-art “target-to-source” optics design software, explain the benefits of an optimized design process. Read more »

Qualified Bluetooth Mesh – Making Lighting Controls Future-Proof

LpR 69 Article, page 88: At Lightfair USA, Siegfried Luger met with Patrick Durand, Worldwide Technical Director at Future Lighting Solutions. One of Mr. Durand’s striking statements was: “Basically, what we need is to future-proof lighting control.” This was the first time that this important aspect was so clearly addressed by a representative of the industry. This led us to asking Mr. Durand to provide LED professional with a technical article to clarify the current situation, explain the technical background that led him to making that statement and to give an idea of which requirements a controls solution must fulfill to be truly future-proof. Read more »

Interactive Lighting Control is Opening New Doors for LED Applications

LpR 69 Article, page 98: Advancements in lighting control technology are allowing for sophisticated interactivity in LED mapping. These new technologies are bridging the gap between lighting control and AI, with the ability to analyze and map data input (such as audio) in real-time. Installations driven by interactive LED control technologies have their place in a variety of application spaces. Manjinder Benning, Founder and CTO of Limbic Media, explains how this new technology works, what its applications are, and what the future of interactive lighting control looks like – not only for end-users, but also for lighting designers and technicians. Read more »

Rethinking the Photometric Data File Format

With increasing computing power, engineering disciplines cannot be imagined without simulations anymore. In lighting, photometric data and electronic processing of this data has become one of the most important tools for luminaire design and lighting design. This data is today provided in IES LM-63 format, a format that meanwhile has come to its limits. P. Eng. (Ret) Ian Ashdown, Senior Scientist at SunTracker Technologies Ltd., explains why the time for a change to a new standard has come and discusses the newly proposed standard and its properties in detail: ANSI/IES TM-33 respectively UNI 1603054. Read more »

Optical Designs to Improve LED Lighting Efficiency of Medical Endoscopes

Lighting efficiency for endoscopic instruments has been deemed very poor, at only about 20%. While laboratory tests demonstrate that fiber optics bending is not problematic, optical simulations clearly show that lighting efficiency is strongly limited by the Étendue. Because of strong geometrical constraints in the light coupling area of an endoscope system, only a radical new optical design can provide significant improvement. Alexander Gaertner and Paola Belloni from the Faculty of Mechanical and Medical Engineering and the Steinbeis Transferzentrum Lichttechnik und Beleuchtungsoptik at the University Furtwangen discuss these issues and propose possible approaches. Read more »

Resources | LpR Article | Research | Micro-Optics | Jan 15, 2019

Smart Design of Freeform Micro-Optical Elements for Thin Direct-Lit Luminaires

LpR 69 Article, page 64: Direct-lit LED luminaires consist of LED arrays. In order to achieve homogenous light distribution a diffuser sheet is placed at a certain height above the LED array. Usually the distance between the LEDs and the diffuser has to be greater than the distance between the LEDs on the array. To overcome this limitation, additional optical elements like freeform lenses are necessary. Christian Sommer, scientist at the Institute of Surface Technologies and Photonics of the Joanneum Research Forschungsges.m.b.H and his colleagues, Claude Leiner, Ladislav Kuna, Paul Hartmann and Franz P. Wenzl propose a smart design concept for an extremely flat, direct-lit lighting system, making use of mask-less laser direct write lithography. Read more »

Evaluating Performance of LED-Based Luminaires

LpR 69 Article, page 48: The wide spread of performance data supplied by manufacturers make it difficult for the professional user to reach an “apple-to-apple” comparison, especially if the data is not based on standardized metrics. This is however critical for the preparation of lighting projects or tender specifications. Experts from LightingEurope have therefore developed a guidance document which recommends a fixed set of performance data for LED based luminaires, with particular emphasis to the useful life and the data which is necessary for lighting application design. Read more »

Zhaga Enables Mechanical IoT-Upgradability for Outdoor LED Lighting Fixtures

LpR 69 Article, page 42: The Zhaga Consortium is a global association of lighting companies that is standardizing LED luminaire components interfaces. The latest specification from Book 18 defines a standardized interface between outdoor LED luminaires and modules for sensing and communication. Dee Denteneer, Zhaga Secretary General, explains how the New Book 18 helps bring the Internet of Things to the outdoor lighting market via smart, upgradeable, future-proof fixtures. Read more »

How to Use the Technologies for Adaptive Lighting

The technologies to provide adaptive lighting are already in the marketplace and are accepted by some jurisdictions. Nonetheless, we have an inadequate understanding of how best to use these technologies, meaning that installations might not serve users well, and in the worst case, might lead to harm. Lighting researchers can generate the knowledge needed to support the best application of adaptive lighting technologies. The International Commission on Illumination (CIE) understands the importance and urgency to deal with problems of adaptive, dynamic and intelligent lighting in all application fields. Hence, this topic is a highlight of CIE’s research strategy. Read more »

UV LED Technology for Emerging Applications in Agriculture

The Ultraviolet (UV) LED market has expanded five-fold in the past decade and is projected to grow to over $1 billion by 2025. A key trend expected to influence the market is the ability to expand into new applications, including agriculture. UV light, at proper frequency and dose, can increase the production of active substances in medicinal and traditional plants and it can also help maintain a healthy growing environment. But to fully take advantage of UV LEDs, some major re-design considerations are required. Terrance Berland, CEO of the Violet Defense Group, the parent company of Violet Gro, will explain which considerations these are; for instance, why it is crucial to incorporate the appropriate lens material. 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 »

Laser Technology for Lighting Applications: A Review and Analysis of a Promising Technology

LpR 68 Article, page 44: LEDs are currently the dominating light source: efficient and cost effective. But LEDs also have some drawbacks. Another interesting technology developed slowly in the shadow of LEDs and has become an interesting solution for some specific applications: GaN based blue solid state laser devices. Although this technology offers some very interesting advantages, it also has challenges. Nicola Trivellin, Matteo Buffolo, Carlo De Santi, Gaudenzio Meneghesso, Enrico Zanoni and Matteo Meneghini from the University of Padova and its spin-off LightCube have been working toward the development of experimental systems and demonstrators and disclose their findings of the comparison between LED and LD systems. Read more »

A Study on Aerosol Jet Printing in LED Module Manufacturing

LpR 68 Article, page 38: LED module manufacturing technologies have certainly improved over the last few years but the requirements have also increased. More components are packed on today’s modules causing additional thermal stress, and, at the same time, the demand for lower cost challenges module manufacturers. So the (re-) search for new materials and new manufacturing processes and manufacturing technologies is still on. Paul Hartmann, Director of the Institute of Surface Technologies and Photonics at the Joanneum Research Forschungsgesellschaft m.b.H., and his team, Andreas Rudorfer, Martin Tscherner, Christian Palfinger, Frank Reil, Franz P. Wenzl with Ioannis E. Seferis, Eugeniusz Zych from the Faculty of Chemistry of the University of Wroclaw investigated the opportunities of aerosol jet printing and proved the applicability for alternative ways of phosphor deposition and integration and to replace wire bonding of dies. Read more »

Research Reports | Smart Lighting + IoT | Resources | LpR Article | Oct 12, 2018

Integrating Lighting in the Internet of Things

LpR 67 Article, page 80: Following the rapid penetration of LEDs, lighting now becomes integrated into the Internet of Things. Over the past three years a consortium of leading European companies worked on the OpenAIS project, partly funded by the EU within the Horizon 2020 program. Now showing the results, the consortium is working on a full size demonstrator. Ben Pronk, System Architect at Philips Lighting Research, and Frank van Tuijl, Project Manager at Philips Lighting show how OpenAIS creates an open ecosystem to enable a wider community to deliver the smartness of light and they explain how it is possible to adapt the system to cater to the diversity of people and demands. Read more »

LED Lighting Requires New Approaches in Optics

LpR 67 Article, page 88: Even though LED technology has been established LEDs still need new approaches in electronics, thermal management or optics to make complete use of their advantages. Marek Škereň, Chief Technology Officer of IQ Structures, explains how new optical devices, with the trade name Nanoptiqs, based on principles of diffraction are applied to achieve improved performance of white light illumination systems. This unique solution is based on full control over the modulation of material and geometric properties of the optical elements at a nano-level. A combination of complex transmission diffractive elements, with specially designed systems of micro-reflectors (produced using an innovative mass-production technique) is also presented as a promising flexible building unit for the construction of new generation luminaires. Read more »

Roll-to-Roll UV Nanoimprint Lithography for Large-Area Nano- and Micro-Structuring of Flexible Substrates

LpR 67 Article, page 50: Cost and time-efficient methods for the fabrication of optical elements are highly desirable in the field of lighting. Imprinting optical structures in combination with large area fabrication turns out to become an effective approach in this regard. In particular roll-to-roll UV nanoimprint lithography (R2R-UV-NIL) has a large potential to set new benchmarks for the fabrication of miniaturized, low-cost and low-weight optics that can be applied in many fields of applications. In the following, the Joanneum Research Forschungsgesellschaft m.b.H team, Claude Leiner, Stephan Ruttloff, Dieter Nees, Anja Haase, Ladislav Kuna, Wolfgang Nemitz, Franz-Peter Wenzl, Christian Sommer, Barbara Stadlober and Ursula Palfinger, led by Paul Hartmann, demonstrates the maturity of the related process chain, combining optical design, direct laser lithography, step&repeat imprinting for shim fabrication and R2R reproduction. 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 »

Abrasion in Transparent Lens Materials for Exterior Aircraft Lighting

Research, Engineering, and Quality Assurance at Kopp Glass, reports how Taber abrasion and high-velocity particulate testing was performed on three different jet aircraft lens materials, including: heat strengthened borosilicate glass (Kopp 9000), hard-coated polycarbonate, and aviation grade acrylic (Makrolon AR and Plexiglas II UVA). 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 »

Method and Circuit to Maintain Constant Light Output for LED Luminaires

Article from LpR 66 | page 80: It is difficult to accurately predict the lifetime or the light output degradation of LED luminaires. A Constant Light Output (CLO) operation is implemented in some of the latest drivers. However, there are many factors that require a different algorithm in terms of time rate and forward current values that are usually not taken into account. Prof.Dr.Eng. Stelian Matei, from the Photometry and Electromagnetic Compatibility Laboratory at Electromagnetica SA, proposes and explains a new method is maintaining the luminous flux over the lifetime of the LED luminaire, considering the luminaire global light degradation. Read more »

Electrical Over Stress - How to Prevent an LED Failing Earlier than Expected

Article from LpR 66, page 70: While LEDS are, in general, very robust, failures still happen due to electrical over stress. Mauro Ceresa, EMEA Field Application Engineer Manager at Cree, will cover all aspects related to electrical over stress, or when an LED fails due to being subjected to a voltage beyond its specification limits. He will explain why the failure occurs and how to prevent this from happening. The article will explain the fundamental aspects of a good PCB layout design and how this is linked to the longevity of an LED. Read more »

Lifetime- and Economic Efficiency Simulation of LED Luminaires in Dymola/Modelica

Article from LpR 66 | page 40: The lifetime of an LED system is usually specified by the LM-80 report using the TM-21 method. Unfortunately, this value is solely valid for one specific application. Sebastian Hämmerle and Thomas Schmitt from the University of Applied Sciences in Vorarlberg developed a new open-source Modelica library for dynamic simulation of LEDs: The DynaLed library. The aim of the work was to evaluate the lifetime and the corresponding economic efficiency of LEDs in dynamic operation by means of the LM-80 report and according to the TM-21 calculation method. Furthermore, it should be possible to use the library for component dimensioning, e.g. the heatsink. The primary task was to develop simulation models which can be parametrized with manufacturer information, e.g. the datasheet, but still provide sufficient accuracy. As an application example an LED louvre luminaire (Article Code: 29001077) from LEDON Lamp GmbH was simulated utilizing the developed library. At the end, results from the lifetime- and the economic efﬁciency simulation were discussed. Read more »

A Near Infrared Enhanced LED Lighting Approach

With the evolution of LED lighting, one topic has come more and more in the focus of the lighting industry: Human Centric Lighting (HCL). While HCL is not clearly defined, a common understanding is that this is light and lighting that supports health and the well-being of humans. Some new proposals are going beyond the approach of providing just visible light in adequate quality, but also to providing invisible radiation, UV and/or NIR that support health and well-being. Some research and the evolution of humans show clear evidence for positive effects of this kind of illumination. Scott Zimmerman, CEO at Silas, presents a new approach that adds NIR radiation to LED illumination. He explains the background of this idea, how it also improves the quality of visible light and discusses the health benefits. Read more »

Full-Color InGaN/AlGaN Nanowire Light-Emitting Diodes for SSL and Displays

III-nitride based nanowire light-emitting diodes (LEDs) have received a staggering response as a future candidate for solid-state lighting and full-color displays due to their unique and exceptional features including drastically reduced polarization fields, dislocation densities as well as the associated quantum confined Stark effect (QCSE) on account of their effective strain relaxation. Moab Rajan Philip and his supervisor Dr. Hieu P Nguyen in the Nano-Optoelectronic Materials and Devices Laboratory at the New Jersey Institute of Technology (NJIT) present astonishing ideas to fabricate and control the color emission of III-nitride nanowire LEDs via molecular beam epitaxy (MBE) growth techniques. The advantage of such LEDs and their characteristics is also discussed. Read more »

Resources | LpR Article | Automotive | Driver IC | Jan 15, 2018

Flicker-Free Control of Individual LEDs in Matrix Headlights

LEDs combine design flexibility with practical, robust circuitry, enabling automotive designers to produce striking headlight designs matched by exceptionally long life and performance. Keith Szolusha, Sr. Design Leader for LED driver products at Linear Technology, and now part of Analog Devices explains how automobile designers are increasingly incorporating LEDs in lighting because they can be arranged in distinctive eye-catching designs - helping distinguish new models from old, or high end from economy. Read more »

Resources | LpR Article | Technologies | Applications | Jan 15, 2018

Multi-Pixel LED Technology Opens New Horizons for Smart Lighting Applications

The evolution of Multi-Pixel LED technology has initiated a giant leap in the development of intelligent lighting systems which are most visible in the automotive industry. Now the first hybrid LED provides smart headlights with more than 1000 individually controllable pixels. Ralph Bertram, who is working on advanced LED device concepts, and Norbert Harendt, who is developing optics solutions for general lighting at Osram Opto Semiconductors, show that automotive lighting is just one of the potential areas in which intelligent selective pixel control can be applied. Options for the use in general lighting, such as information display for outdoor, indoor, retail or industrial applications, are very versatile. Read more »