LED professional Review (LpR) - Articles
Energy Efficiency and Thermal Simulations of a Retrofit LED Light Bulb by the University of Turku
Mika Maaspuro and Aulis Tuominen from the University of Turku investigated the energy efficiency of a LED driver mounted inside a retrofit light. The heat generation of the LEDs and the driver of the light bulb have been simulated and measured. A thermal model for the light bulb has been created and simulated using a Finite-Element-Method (FEM) software. Parameters of the model have been adjusted to match the temperature measurements which have been done with IR-camera and thermocouples.
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Energy Efficiency and Thermal Simulations of a Retrofit LED Light Bulb by the University of Turku
Mika Maaspuro and Aulis Tuominen from the University of Turku investigated the energy efficiency of a LED driver mounted inside a retrofit light. The heat generation of the LEDs and the driver of the light bulb have been simulated and measured. A thermal model for the light bulb has been created and simulated using a Finite-Element-Method (FEM) software. Parameters of the model have been adjusted to match the temperature measurements which have been done with IR-camera and thermocouples.
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Sensors and Feedback Control of Multi-Color LED Systems by MAZeT GmbH
To obtain stable and consistent lighting conditions within the black body range with LED systems, especially RGBx systems is a challenging task. Feedback controlled systems are expensive, but the best solution. Here, the question of which type of sensor accomodates the given application best,
arises. Thomas Nimz, Fredrik Hailer and Kevin Jensen from MAZeT GmbH discuss different options based on their scientific studies on LED systems with four or more different LEDs considering secondary conditions like color rendering index.
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Mesopic Photometry - An Accurate System of Road Lighting Evaluation by Surya Roshni Ltd.
For a long time, photopic vision was the basis for all light measurement tasks, but today this approach is challenged. According to several research results, it seems that mesopic vision should be used as a basis to evaluate street lighting applications or other low level lighting applications.
Prija Jain from the Executive Design and Development (Photometry & Optics) department of Surya Roshni Ltd. in India gives us an overview on the recent status of the discussion, explains it and shows the resulting consequences.
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Practical Results of a Gas Station Refurbishment with LED Luminaires by the Electromagnetica SA Semiconductor Lighting Centre
Perfect lighting at a gas station is very important for competitiveness. But a conventional lighting system is
also a costly and energy demanding installation with high maintenance costs. Stelian Matei from the Electromagnetica SA Semiconductor Lighting Centre shows how a well-planned upgrade of conventional lighting to LED lighting lowers energy consumption and maintenance and, therefore, costs.
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Practical Results of a Gas Station Refurbishment with LED Luminaires by the Electromagnetica SA Semiconductor Lighting Centre
Perfect lighting at a gas station is very important for competitiveness. But a conventional lighting system is
also a costly and energy demanding installation with high maintenance costs. Stelian Matei from the Electromagnetica SA Semiconductor Lighting Centre shows how a well-planned upgrade of conventional lighting to LED lighting lowers energy consumption and maintenance and, therefore, costs.
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Flexible OLEDs for Lighting Applications by the Holst Centre
While OLEDs already have successfully found their way into display applications, the breakthrough in lighting applications is still pending. The reasons are diverse, but cost is one major point. Another reason is the current edge of inorganic LEDs giving reasonable design opportunities in many
standard applications. However, there are applications where OLEDs could score, especially the flexible OLEDs. But even these OLEDs need to become cheaper to be applied widely. The Holst Centre and partners aim to develop generic technologies for large area flexible OLEDs which can be processed with roll-to-roll (R2R) technology. Process Engineer Tansim Baig gives an example and an overview
of the current status of the development.
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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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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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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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Reliable Thermal Management of High-Power LEDs by Haeusermann
Stefan Hörth believes that FR4 PCBs can easily replace IMS PCBs and even open new fields of LED applications. Haeusermann’s HSMtec Product Manager demonstrates that common FR4 laminates, including special copper filling, will sufficiently withstand the heat of HB LEDs.
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EMI Problems in TRIAC Dimmable LED Drivers by RECOM Lighting
TRIAC dimming adds a dimension to Power Factor (PF) and Total Harmonic Distortion (THD) that is rarely defined by LED driver manufacturers. Bianca Aichinger, Product Marketing Manager at RECOM Lighting, examines the relationship between PF, THD and harmonics and explains why this relationship can change as soon as the LEDs are dimmed, thus causing increased EMI and undesirable visible effects
such as LED flashing and flicker. The European standards for EMC and Harmonics are only specified for full load and in the non-dimmed condition. In practice, there are often dimmer/driver/LED load conditions which may meet the regulations when undimmed, but fail significantly if dimming is used.
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An Economical Omnidirectional A19 LED Light Bulb by the Industrial Technology Research Institute
Since 2009, when the Japanese government was vigorously promoting LED bulbs in end-market applications, they have become mainstream commodities in the LED lighting market. Chen-Peng Hsu, project manager of Electronics and Optoelectronics Research Laboratories at Industrial Technology Research Institute (ITRI), introduces the R&D 100 award-winning invention of an omnidirectional
A19 LED light bulb that is light weight and economical.
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The Influence of LED Emission Characteristics on the Efficiency of Lighting Systems by Osram Opto Semiconductor
In general lighting, efficiency is the main focus. Under specific operation conditions, the main issue appears to be luminous flux. Dr. Roland Schulz, application engineer in the Solid State Lighting division at Osram Opto Semiconductor, takes a deeper look at the influence of LED radiation characteristics.
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The Influence of LED Emission Characteristics on the Efficiency of Lighting Systems by Osram Opto Semiconductor
In general lighting, efficiency is the main focus. Under specific operation conditions, the main issue appears to be luminous flux. Dr. Roland Schulz, application engineer in the Solid State Lighting division at Osram Opto Semiconductor, takes a deeper look at the influence of LED radiation characteristics.
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How Silicones are Evolving to Meet the Growing Needs of the LED Lighting Industry by Dow Corning
There are different materials for optics in lighting applications. The lighting application engineers François de Buyl, Martijn Beukema and Kevin van Tiggelen from Dow Corning are convinced that silicone’s unique qualities help to expand options in the design and molding of LED packaging
components, as well as components for lamp and luminaire applications.
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Labeling and Certification Testing Issues by UL
Arno Grabher-Meyer from LED professional summarizes several issues regarding certification and certification processes which were discussed with David Edwards, an expert in testing and compliance engineering for consumer products at UL.
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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.
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Thermal Management for LEDs Beyond Thermal Conductivity Values by Electrolube
Specifically designed and formulated chemical products are widely used in the electronics industry for a vast array of applications. Jade Bridges, European Technical Support Specialist at Electrolube explains why such products have become an essential factor in ensuring the performance and
quality of electronic devices, whether it is during PCB manufacture or for the protection of components or complete devices.
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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.
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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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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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Predictive Simulation to Virtually Test Product Design and Reduce Time to Market by Trinseo
With technical progress and new regulations, shorter product cycles are a continuous challenge for OEMs. Modelling is one measure to cut time to market efficiently without compromising product quality. Trinseo Technical Service & Development specialists Kersten Terry and Berend Hoek explain the process of computer-based simulation, specifically applied to injection molded plastic parts. Through case studies, they showcase how Trinseo’s Application Engineering Development resource facilitates more effective LED-lighting development relative to part design, tool design and material
selection by modelling “real world“ performance.
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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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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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The Role of Special Optics in Human Centric Lighting and Architecture by Suleyman Turgut and Luminit LLC
While Human Centric Lighting is relatively new and a topic of some debate, few can argue over the benefits of creating more natural lighting conditions in offices, retail spaces and other architectural settings. Anthony Ang, Optical Engineer, Suleyman Turgut, Director of Sales, and Mary Ann Giorgio,
Marketing Communications Specialist at Luminit LLC show how special or “tertiary” optics, such as diffuser and direction film, can play a crucial role in Human Centric Lighting or lighting that takes into account the emotional and biological needs of humans.
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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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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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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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Embedded Lighting - Developing New Lighting Applications for Modern Architectural Projects by Philips Lighting
When the era of LED lighting started, everybody talked about the new age of lighting with new opportunities. While many lighting concepts are still pure replacements of the conventional light sources, with the maturation of this technology, more and more new concepts are realized, and the
future perspectives are even more exciting. Brad Koerner, Venture Manager - Philips Luminous Patterns at Philips Lighting, shows examples, explains why such new concepts are desirable, and discusses which technologies support the introduction of new lighting applications.
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