Trends

Technology | Jun 01, 2006

Photonics crystals improve LED efficiency

Figure 1 A 50% increase in efficiency is a significant stride toward being viable sources for solid-state lighting. Read more »

Technology | May 17, 2006

Aluminum Nitride Light Emitting Diodes with the Shortest Wavelength towards Dioxin, PCB Decomposition Technology

Figure1 Aluminum Nitride, "Shortest Light-Emitting Semiconductor" Nippon Telegraph and Telephone Corporation (NTT) has observed light of 210-nm wavelength from aluminum nitride (AlN) light emitting diodes (LED). Read more »

Technology | Feb 16, 2006

Method May Help Optimize Light-emitting Semiconductors

What do you see in these Rorschach-blot-like images? JILA physicists see the once-hidden electronic behavior of semiconductors. The computer plots show how energy intensity (ranging from low in blue to high in red) varies as electronic structures called excitons absorb laser light and emit energy at various frequencies. The pair of similar "butterflies" indicates that an exciton is absorbing and emitting energy in a predictable pattern. Physicists at JILA have demonstrated an ultrafast laser technique for "seeing" once-hidden electronic behavior in semiconductors, which eventually could be useful in more predictable design of optoelectronic devices, including semiconductor lasers and white light-emitting diodes. Read more »

Technology

Electrical Considerations of LED Bulbs

Figure 8: LED bulb with an isolated driving and feedback circuit. Governments all over the world regulated the future use of the inefficient incandescent lamps. For example, the member states of the European Union agreed to a phasing out of incandescent lamps by 2012. The initial European-wide ban applies the first step to “nondirectional” light bulbs. The first types of bulbs to be banned are frosted (non-clear) bulbs and clear bulbs over 100 W, which will be phased out completely by September 2009. The power limit will be moved down to lower wattages, and the efficiency levels raised by the end of 2012. Read more »

Technology

Microstructured Optics for LED Applications

Figure 1: Common types of optics. Optics for use with Light Emitting Diodes are described. Microstructured optics are available and customizable for a wide variety of applications. A few of these will be touched on. A methodology of designing these optics and the photometrics of the typical technology is overviewed. Read more »

Technology

High Quality GaN Substrates for Modern LED Technology

Figure 3: AFM data illustrating the NI density for a) sample A and b) sample B. The overgrowth of sparse NIs can result in formation of new islands (c). Using increased reactor pressure the formation of new islands during HT overgrowth can be suppressed (d). All the scans are 10 μm × 10 μm. It is well known that modern III-nitride based technologies for light emitting diode (LED) production include (as an initial inevitable step) the preparation of GaN templates. Such GaN templates are usually delivered on foreign substrates possessing high lattice mismatch with respect to GaN layers, e.g., sapphire or silicon carbide substrates. The growth of GaN layers on highly mismatched substrates occurs via the formation of 3D islands with their following coalescence [1]. Such growth mode results in an extremely high density of threading dislocations (TDs) up to 1010–1011 cm–2 in the layer interior [1]. These TDs are known as main sources for the deleterious performance of LEDs and other GaN based electronic and optoelectronic devices [2]. Therefore there exists an ultimate necessity in the developing of effective and low-cost recipes for low TD density GaN template manufacturing. Read more »

Technology

Measurement of LEDs

Figure 5: NIST gonio-spectroradiometer for the total spectral radiant flux scale realization Various new types of light emitting diodes (LEDs) are being developed and introduced for general illumination and other applications, and there are increasing needs for accurate measurements of various optical parameters of LEDs. Traditional standard lamps do not meet the calibration needs for LED measurements as LEDs differ substantially from traditional lamps in terms of physical sizes, flux levels, spectra, and spatial intensity distributions. Read more »

Technology

Off-Line LED Control Circuit

Figure 1: Fluorescent dimming ballast block diagram Resonant mode topologies offer many benefits over traditional buck, boost and flyback solutions. These include soft-switching, higher operating frequencies, higher power density and higher efficiency. Electronic ballast designs for fluorescent lighting applications have already been taking advantage of these benefits for many decades. Much can be learned from electronic ballast circuits and applied to LED driver circuits. This article compares the load requirements for fluorescent lamps and LEDs, explains the functionality of a new dimming electronic ballast control IC, and describes a new resonant mode control circuit for LEDs that uses the new IC. Experimental results of the new circuit are also presented and summarized to show final performance. Read more »

Technology

Primary and Secondary Optic Materials - LED Luminaire Performance and Lifetime

Figure 1: LumiBright LE line of light engines for commercial applications and incorporating high efficiency primary optics, photosensor, and thermistor on a high thermal conductivity metal core PCB in one package. Numerous articles have been published regarding the lifetime of Light Emitting Diode (LED) luminaires, however, the primary focus has typically been on the lifetime of the LED die itself. Given that the LED luminaire is a system, it is important to recognize all aspects of the system that can affect or limit lifetime. Read more »

FEATURED

Emergency Lighting Just Got Smarter

Emergency Lighting Just Got Smarter NEW NOW: OSRAM’s standalone solution for emergency lighting testing, reporting and maintenance. Meet the QBM DALI EL-T CONV, a converter transforming existing DALI emergency luminaires into wireless ones, all controlled by the same lighting system. Its benefits? Allowing you to design all the ... Read more »

FEATURED

Continuous versus Discrete Calibration Sources: Consideration for Use

Continuous versus Discrete Calibration Sources: Consideration for Use Rapid advancements in the field of solid-state lighting have presented opportunities for the use of LED-based systems for calibrations typically performed with lamp-based sources. Their highly efficient and long-lived performance, rapid power up, and compact size have made LED-based sources an ... Read more »

FEATURED

LUXTECH Offers First Compelling Flex Modules Designed to Replace Traditional Rigid Modules: LUXroll (UL Listed)

LUXTECH Offers First Compelling Flex Modules Designed to Replace Traditional Rigid Modules:  LUXroll (UL Listed) The Indirect Costs of Using Rigid Boards Make Switching to Flexible LED Modules a Compelling Choice. Read more »

EDITORIAL

New LUXEON Rubix Cyan LED Enables 96-98 CRI Across CCT Range in Color Driven Solutions for Entertainment, Stage, and Studio

New LUXEON Rubix Cyan LED Enables 96-98 CRI Across CCT Range in Color Driven Solutions for Entertainment, Stage, and Studio Lumileds added cyan, its eighth color, to the LUXEON Rubix high-power LED family enabling multi-color driven systems to produce very high CRI white light that is so important in entertainment lighting. Adding the cyan LED fills a significant wavelength gap between blue and green in a system and ... Read more »

EDITORIAL

New date: Light + Building Autumn Edition 2022

New date: Light + Building Autumn Edition 2022 Frankfurt am Main, January 10, 2022. As the pandemic situation continues to develop very dynamically, Messe Frankfurt is postponing the world's leading trade fair for light and building technology to autumn 2022. Last December, intensive discussions with customers and cooperation partners had ... Read more »

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