Articles & Interviews
LpR Article | Technologies
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Jun 08, 2016
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.
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Jun 08, 2016
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.
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Jun 09, 2016
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.
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Research
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Jun 09, 2016
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.
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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.
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Jun 20, 2016
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.
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Jun 20, 2016
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”.
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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.
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Jun 20, 2016
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.
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LpR Article | Technologies
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Jun 20, 2016
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.
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LpR Article
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Jun 20, 2016
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.
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Jun 20, 2016
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.
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Jun 20, 2016
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.
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LpR Article | Technologies
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Jun 20, 2016
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.
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Jun 20, 2016
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.
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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.
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LpR Article | Technologies
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Jun 21, 2016
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.
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LpR Article | Technologies
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Jun 21, 2016
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.
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Jun 21, 2016
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.
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LpR Article
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Jun 27, 2016
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.
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