Articles & Interviews

LpR Article | Jun 28, 2016
Natural Design for Heat Sinks
Natural Design for Heat Sinks The luminous flux of LEDs decreases with the rise of the operating temperature. Therefore the dissipation of the heat is, aside from the efficiency of the LED chip itself, an essential part in the development of efficient LED systems. Christian Herbold and Cornelius Neumann from the Light Technology Institute at the Karlsruhe Institute of Technology analyzed natural inspired shapes and show an approach to heat sinks that combine high thermal performance with a high aesthetic value. Read more »
LpR Article | Technologies | Jun 28, 2016
LED and Lens Degradation Through Volatile Organic Compounds
LED and Lens Degradation Through Volatile Organic Compounds In general, LEDs are very resistant light sources. Nevertheless, glues, conformal coatings, o-rings, gaskets, and potting compounds, all materials that are frequently used in the construction of LED based luminaires or lamps and often contain volatile organic compounds (VOCs) may have a negative impact on performance, reliability and lifetime. Edward Steinke, application engineer at Cree, explains the set of problems and how to prevent these issues based on Cree’s products, using their test kit components, as well as components for lamp and luminaire applications. Read more »
LpR Article | Technologies | Jun 28, 2016
Reliability Oriented Design of LED-Based Light Sources
Reliability Oriented Design of LED-Based Light Sources The transition from traditional light sources to SSL systems requires a different design philosophy to achieve the advantages offered by LED light sources. The key approach is based on the parallel design of thermal, electrical, optical and spectral properties of the light source. Matteo Meneghini, Gaudenzio Meneghesso, Enrico Zanoni and Matteo Dal Lago from the Department of Information Engineering at the University of Padova, and Nicola Trivellin from LightCube SRL explain this approach including the importance of the electrical management of LEDs, comparing modulation techniques to constant current, differentiating between versatility and efficiency. Read more »
LpR Article | Jun 28, 2016
Contactless LED Technology
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 | Jun 27, 2016
Status of Micro- and Nanostructured 3D LED Technologies
Status of Micro- and Nanostructured 3D LED Technologies Conventional LEDs are planar, two-dimensional (2D) devices that emit light from a thin material layer at or near their flat surface. The vast majority of LEDs are made of GaN and InGaN material requiring expensive substrate wafers made of sapphire, silicon carbide or gallium nitride. The 3D WireLED technology uses silicon wafers for wafer diameters of 8 inches or larger. On each wafer, millions of vertical microwires and microrods of GaN are grown, each with a diameter of less than one micron. Mr. Arno Grabher-Meyer and Mr. Siegfried Luger from LED professional, talked with the General Manager of Aledia, Mr. Giorgio Anania about the status of this innovative technology. Read more »
LpR Article | Jun 21, 2016
Using Integrating Spheres Correctly to Measure LEDs
Using Integrating Spheres Correctly to Measure LEDs LEDs have opened up new dimensions of design freedom, allowing architects and designers to give free rein to their creativity. Light-emitting diodes permit manifold design solutions as a light source in illumination products. However, a suitable measuring method for comparing key technical data is required in order to get the best out of the diversity of illumination products available. Mikolaj Przybyla from GL OPTIC, a Just Normlicht GmbH division, explains crucial product requirements and what to take care about when calibrating a measurement system. Read more »
LpR Article | Technologies | Jun 21, 2016
Safety Issues for LED Drivers with PWM Operation Modes by Product Approvals Ltd.
Safety Issues for LED Drivers with PWM Operation Modes by Product Approvals Ltd. In many cases LED drivers manage their output power with PWM controlled switched mode power supply-topologies. The output voltages are filtered and normally DC voltages with low ripple apply at the output connectors of LED drivers. During dimming these circuits can behave very differently and therefore safety issues may arise. Siegfried Luger, CEO at Luger Research e.U. and John Showell, Product Safety Consultant at Product Approvals Ltd. have a closer look at those operation modes and the requirements on voltage limits. Read more »
LpR Article | Technologies | Jun 21, 2016
Optimization of SSL LED Devices by Osram Opto Semiconductors
Optimization of SSL LED Devices by Osram Opto Semiconductors There are different levers to improve LED performance. Ralph Bertram, application engineer for SSL products, and Alexander Wilm, key expert in the SSL application engineering department at Osram Opto Semiconductors, have a look into the device itself and explore the principal limitations of the different contributors to device efficacy. They show how to balance driving current and chip size to define the right LED, and explain the impact on performance and system costs of LED packages for the intended lighting task approaches for lighting strategies. Read more »
LpR Article | Jun 20, 2016
Concept of a Time-Proven LED Luminaire Design and Manufacturing Process by Lumitec Lighting
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 | Jun 20, 2016
Discomfort Glare Perception of Non-Uniform Light Sources in an Office Setting
Discomfort Glare Perception of Non-Uniform Light Sources in an Office Setting LED based luminaires with different luminance patterns and recently, with increasingly non-uniform luminance patterns are becoming mainstream. This trend makes discomfort due to glare an important topic. Based on an office setting and the comparison of results from three different regions, L. M. Geerdinck, J. R. Van Gheluwe and M.C.J.M. Vissenberg from Philips Research have reviewed the currently used formulae to predict discomfort glare to ascertain if they are still valid. Read more »
LpR Article | Technologies | Jun 20, 2016
LED Light Spectrum Enhancement with Transparent Pigmented Glazes
LED Light Spectrum Enhancement with Transparent Pigmented Glazes While LED bulbs have the distinct economic advantages of using less energy, producing less heat and lasting years longer than traditional incandescent bulbs, when objects are viewed under LED light, they frequently appear to be of different colors than when viewed in sunlight or with incandescent lights. Jan-Marie A Spanard from Light Spectrum Glazes proposes and explains an approach to optimize the spectral distribution of LED light to overcome this weakness. Read more »
LpR Article | Jun 20, 2016
Lighting & Building Automation Technologies
Lighting & Building Automation Technologies The transition from traditional lighting technology to LED is old news. People in the lighting business no longer talk about the “LED Revolution”. Today’s revolution, perhaps spurred on by LED technology, is in building automation and lighting controls. Lighting experts know that while LED products have the potential to achieve terawatts of power savings worldwide over the next decade, even larger power savings might be achieved through effective lighting control and building automation systems. Greg Galluccio, Director at Leviton Manufacturing discusses lighting load-shedding strategies, such as daylight harvesting, occupancy sensing, task management and demand response as well as the trends towards the interaction of lighting control with other building functions. Read more »
LpR Article | Jun 20, 2016
Advanced Passive Thermal Management Solutions for High Power LEDs by Advanced Cooling Technologies (ACT)
Advanced Passive Thermal Management Solutions for High Power LEDs by Advanced Cooling Technologies (ACT) There are two main solutions to improve passive thermal management in LED devices. One is to increase the surface area of a heat sink. This requires additional size, weight and material and offers only marginal improvement. The second solution is to increase the thermal conductivity between the heat source and the sink. The latter is supported by well-established technologies like heat pipes and vapor chambers. Richard Bonner, Manager for Custom Products, and Peter Ritt, Vice President at Advanced Cooling Technologies (ACT) give insight into the latest developments and explain how they work, how they are designed and applied correctly, and discuss their opportunities, advantages and limitations. Read more »
LpR Article | Jun 20, 2016
Light Guide Technology for Obtaining a Different Bi-Directional Direct/Indirect Light Emission Pattern
Light Guide Technology for Obtaining a Different Bi-Directional Direct/Indirect Light Emission Pattern Market requirements ask for a solution for use in suspended light fixtures that will allow the light to be distributed upward, for indirect illumination, as well as downward, for direct illumination. However, existing light guide technology typically produces fairly indirect light and relatively uncontrolled distribution. Brett Shriver, Vice President at Global Lighting Technologies, explains a new approach with individual light extraction features used within the light guide in order to control light in multiple directions and provide the required semi-Lambertian distribution in the downward direction with low glare while obtaining a bat-wing type distribution in the upward direction. Read more »
LpR Article | Technologies | Jun 20, 2016
High Color-Rendering, Full-Visible-Spectrum LEDs by Soraa
High Color-Rendering, Full-Visible-Spectrum LEDs by Soraa The first wave of conventional white LEDs primarily focused on lumens per Watt. These LEDs were based on phosphor down-conversion using primary blue “pump” emission. Currently LEDs are catching up in regards to light quality using different approaches. Aurelien David, Senior Principal Scientist and Mike Krames, Chief Technology Officer at Soraa explain their technology approach of violet-pumped, full-visible-spectrum LEDs, and the interrelated challenges and advantages. Read more »
LpR Article | Jun 20, 2016
Thermal Transient Testing of LEDs for More Reliable SSL Products by Mentor Graphics
Thermal Transient Testing of LEDs for More Reliable SSL Products by Mentor Graphics An LED device’s reliability, useful operating lifetime and luminous flux are basically determined by the junction temperature; therefore, so is the lifetime and reliability of the final SSL application. Thermal transient testing is now supported by new industrial laboratory testing standards published by JEDEC. Dr. Andras Poppe, Mechanical Analysis Division, MicReD, at Mentor Graphics will explain the corner stones of this standard and discuss application examples. This includes measurement of the RthJC, test-based thermal modeling of the LED package, hot lumens prediction, and monitoring of degradation of the thermal interfaces during life-time test, to name just a few. Read more »
LpR Article | Jun 20, 2016
Development of a Workflow for Colored Ray Data by TechnoTeam Bildverarbeitung GmbH
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 | Jun 20, 2016
Advanced Optical Plastics Materials for LED Lighting Applications by Styron LLC
Advanced Optical Plastics Materials for LED Lighting Applications by Styron LLC Across a range of lighting solutions, Light Emitting Diodes have emerged as the clear choice for industry and consumers alike. Government regulations and consumer preference for more environmentally-conscious, energy-efficient products have caused manufacturers to develop solutions for the marketplace that offer new levels of energy efficiency, durability and long life. While the technology has evolved, so have the materials that go into the finished product. Claude Van Nuffel, Eric Wu, Peter Jackson and Marta Sans Peña from Styron LLC discuss versatility and one-of-a-kind properties of plastic – especially polycarbonate and polycarbonate blends – and why they have become the “materials of choice”. Read more »
LpR Article | Jun 20, 2016
Managing Manufacturing and Supply Chain Challenges in LED Luminaire Design by Sanmina
Managing Manufacturing and Supply Chain Challenges in LED Luminaire Design by Sanmina Today’s luminaires are often complicated lighting systems and have a wide range of applications from in-home luminaires and retail to very high power outdoor lighting. This causes several challenges in both design and manufacturing. Some of these problems may have already been solved by design and manufacturing firms having expertise with LED luminaire design and manufacturing. Gelston Howell, Senior Vice President at Sanmina explains how to manage some of these design, manufacturing and supply chain challenges by using examples. Read more »
LpR Article | Jun 20, 2016
Cost Saving Potential with Automation and Well Designed Processes by BJB GmbH
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 »
Research | Jun 09, 2016
Blue Wavelengths of LED Light Negatively Affect Milk Quality
Blue Wavelengths of LED Light Negatively Affect Milk Quality Matt Hayes, managing editor and social media officer for the College of Agriculture and Life Sciences, and Alina Stelick, research support specialist in the Department of Food Science, report at the Cornell Chronicle of June 8th, 2016 that Cornell researchers in the Department of Food Science found exposure to light-emitting diode (LED) sources for even a few hours degrades the perceived quality of milk more so than the microbial content that naturally accumulates over time. Their study determined milk remained at high-quality for two weeks when shielded from LED exposure, and consumers overwhelmingly preferred the older, shielded milk over fresh milk stored in a typical container that had been exposed to LED light for as little as four hours. Read more »
LpR Article | Jun 09, 2016
Form Factor Luminaires and Light Effects
Form Factor Luminaires and Light Effects If luminaires designed for traditional light sources are simply retrofitted with LED light sources like it occurs in the so-called “1st wave of LEDification”, they will always fall short of expectations in many points. Herbert Weiß and Thomas Noll from Osram GmbH, Martin Möck from the University of Erlangen-Nuremberg, Martin Creusen from Philips Lighting, and Friedhelm Holtz from Insta Elektro GmbH explain why these shortcomings were addressed and which solutions were developed in the EnLight project. Read more »
LpR Article | Jun 08, 2016
DMI Specification Defines Electrical Interface between LED Drivers and Modules
DMI Specification Defines Electrical Interface between LED Drivers and Modules Enabling LED modules and LED drivers to be fully interchangeable at the component level requires a specification for the electrical interface between the driver and module (DMI). Arnulf Rupp of Osram GmbH, a member of both the Zhaga Consortium and MD-SIG, explains the role of both organizations in developing and implementing a consistent, easy to use, cross-vendor DMI specification. Read more »
LpR Article | Technologies | Jun 08, 2016
InGaN Nanowires Make Light Mixing Efficient and Smart
InGaN Nanowires Make Light Mixing Efficient and Smart The correlated color temperature (CCT) of high color rendering index (CRI) LED lighting systems can, in principle, be tuned over a wide range. As an alternative approach to conventional phosphor based LEDs, a full-color LED array consisting of red, green and blue (RGB) InGaN based nanowire LEDs monolithically integrated on a micro-scale level has been proposed and fabricated. J. Lee from the Nano Electronics Lab at the Samsung Advanced Institute of Technology, Renjie Wang, Hieu P. T. Nguyen, Ashfiqua T. Connie, Ishiang Shih, and Zetian Mi from the Department of Electrical and Computer Engineering at McGill University in Montreal explain how this technology works and how the three multi-color subpixels on the same chip can be separately biased and can exhibit full-color emission which can be tuned controllably in a wide CCT range. Read more »
LpR Article | Jun 08, 2016
Zhaga Evolves: Focus on Component Standardization Drives New Book Development
Zhaga Evolves: Focus on Component Standardization Drives New Book Development With new specifications covering COB LED arrays, LED drivers, and other LED modules and light engines, Zhaga is making rapid progress in standardizing these types of components in response to the needs of the market. Musa Unmehopa, Secretary General of the Zhaga Consortium, and Tim Whitaker, Director of Marketing Communications of the Zhaga Consortium, describe how Zhaga is evolving and changing its focus in a number of areas. Read more »
LpR Article | Research | Jun 08, 2016
A Graphene-Based, Spectrally Tunable, Flexible Field-Effect Light-Emitting Device by the Tsinghua University and the Tsinghua National Laboratory for Information Science and Technology
A Graphene-Based, Spectrally Tunable, Flexible Field-Effect Light-Emitting Device by the Tsinghua University and the Tsinghua National Laboratory for Information Science and Technology The continuous tuning of the emission spectrum of a single light-emitting diode (LED) by an external electrical bias is of great technological significance as a crucial property in high-quality displays and may be used in high quality lighting applications, yet this capability has not been demonstrated in existing LEDs. Graphene, a tunable optical platform, is a promising medium to achieve this goal. Xiaomu Wang, He Tian, Mohammad Ali Mohammad, Cheng Li, Can Wu, Yi Yang, and Tian-Ling Ren from the Institute of Microelectronics at the Tsinghua University in Beijing and the Tsinghua National Laboratory for Information Science and Technology (TNList) demonstrate a bright spectrally tunable electroluminescence from blue (~450 nm) to red (~750 nm) at the graphene oxide/reduced-graphene oxide interface. Read more »
LpR Article | Technologies | Jun 08, 2016
Mastering Thermal Issues in LED PCB Design & Laminate Selection by Ventec Europe
Mastering Thermal Issues in LED PCB Design & Laminate Selection by Ventec Europe LED applications are not the only applications that are driving the need for thermal issues to be considered and mastered in PCB design, but they are certainly amongst the most challenging. Designing LED PCBs requires many considerations and key are those that arise from multiple heat sources in close proximity. Martin Cotton, Director OEM Technology of Ventec Europe describes the process and criteria used when designing PCBs (Printed Circuit Boards) for use in LED applications using thermally conductive IMS (Insulated Metal Substrates). He goes into technical detail with charts and diagrams that explain everything the designer would need to consider when selecting a laminate and commencing a design. Read more »
LpR Article | Research | Jun 07, 2016
Al2O3 Coated Europium- Activated Aluminum Silicon Nitride for COB LED Technology by the Graz University of Technology and Tridonic Jennersdorf
Al2O3 Coated Europium- Activated Aluminum Silicon Nitride for COB LED Technology by the Graz University of Technology and Tridonic Jennersdorf Eu2+ activated nitride phosphors have drawn much interest for solid state lighting because of their interesting photoluminescence. While they show excellent optical properties, they are hygroscopic and have the potential of being degraded by atmospheric moisture and high temperatures. A coating layer on the surface is an effective method to improve stability against moisture and oxidation. For use in chip on board technology, Nika Mahne, master student at the Institute of Inorganic Chemistry, A. Reichmann, B. Bitschnau, R. Fischer, from the Graz University of Technology, and F. Schrank from Tridonic Jennersdorf propose an approach where a CaAlSiN3:Eu2+ [1, 2, 3] phosphor was coated with Al2O3, obtained via a Brønsted precipitation reaction based on a solution-coating process from a mixture of aluminum halide with a base after annealing at a temperature of 400°C. Read more »
LpR Article | Technologies | Jun 07, 2016
New Class of Siloxane Polymers for Advanced LED Packaging
New Class of Siloxane Polymers for Advanced LED Packaging Packaging presents a major challenge to further improve LED device efficiency and reliability. A novel class of high stability siloxanes forms a technology platform to address such opportunities in die attach, encapsulation, and light outcoupling applications. Dr. Juha Rantala, CEO & Founder, Dr. Joerg Rockenberger, Director Application & Business Development, Dr. Jyri Paulasaari, Vice President Technology, Dr. Jarkko Heikkinen, Director Inks & Pastes. Markus Laukkanen, Application Manager, and Dr. Janne Kylmä, Vice President Engineering & Production at Inkron Oy explain the material properties and give examples of how these new materials in combination with novel nanomaterials enable products fully compatible with current process tools and flows while having superior properties. Read more »
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