Efficient lighting solutions

With the establishment of LED lighting, the lighting industry is currently experiencing a revolutionary and extensive transition in technology that can be compared to the discovery of the incandescent lamp or with the advance to fluorescent lamps. The adaptation of standards and norms can hardly keep up with such a wide-ranging and rapid transition, and in such times as this there are usually no uniform terms of language, meaning that with LED until now, communication has differed concerning quality criteria and data.

The verification of products and their compatibility in such cases is hardly possible, and this causes uncertainty in the market. The aim is therefore to achieve a uniform understanding concerning LED lighting, in addition to supplying fundamental LED information.

"THE COMPLETE PACKAGE HAS TO BE RIGHT"

By now, LED technology has established itself in all applications. But which important details should still be considered and which new trends are influencing the lighting sector?

Dietmar Zembrot, Member of the TRILUX Executive Board/Technology and Dirk Pietz, Head of Product Management, take a position.

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The LED – one of the most efficient light sources

With major potential for saving energy

With a service life of approximately 50,000 operating hours – and often significantly more with outdoor luminaires – the LED is far superior to most other light sources. This corresponds to 5.7 years of continuous operation or over 2,083 days, 24 hours per day. The service life of an LED is influenced for example by temperature, electric current and voltage, humidity, chemicals, radiation and mechanical forces.

The sensitivity of an LED to mechanical factors is however relatively low compared to other lamps due to a lack of movable or breakable parts and its compact construction size.

FAQ: LED lighting

Temperature in the junction area

One of the most important factors for the performance and service life of an LED is the temperature in the junction area, the so-called Junction Temperature Tj. The luminous efficiency and service life of LEDs decrease with increasing temperature. This is why thermal management is highly important.

LED or fluorescent lamp

The decision between LED or fluorescent lamp cannot be made in general as it is influenced by many different framework conditions, but in all cases the quality of the light source used is decisive. We support you with expert advice in finding the most optimal, energysaving and cost-cutting lighting solution for your specific applications. Simply contact us.

Total failure and parametric errors

If the service life of an LED is considered, a differentiation is made between parametric errors, i.e. output loss, and a total failure. With output loss the luminous flux decreases over time until it falls below a threshold level that is acceptable for the specific application area. Usually, the 50,000 hour service life relates to the L70 value, meaning after 50,000 hours luminous flux is reduced to 70 % of initial output. In contrast to this, total failures, i.e. defective LEDs that no longer emit light, are specified with the aid of the B value (mortality). A service life of 100,000 hours with a B50 value specifies that after 100,000 hours half of the LED has failed.

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Functionality of LED

With application of voltage to the pn junction, the size of the junction area can be influenced. Here polarity is decisive. If the n-conductor (electron donor) is combined with the negatively charged cathode, then electrons push in from the n side in the direction of the junction area to the anode. At the same time holes migrate from the p side (connected with the positively charged anode) towards the junction area or cathode. The junction area becomes smaller with increasing voltage until the forward voltage is achieved and the diode conducts current. If though the n-conductor is combined with the positively charged anode, electrons are attracted by the anode so that the junction area increases and no current can flow.

LED cooling system

Although light emitted from an LED contains no infrared components and is thus "cold", high temperatures are created during recombination in the semiconductor crystal. This almost punctual heat load has to be dissipated via a sophisticated cooling system and uniformly distributed. In principle the LED cooling system is similar to a computer processor: the PCB on which the LED is mounted is pressed with a heat sink to ensure optimal heat transition. The form and construction of the heat sink depend among other factors on the luminaire geometry, the installation location and the material used.

LED components

At first sight an LED assembly consists of a series of simple components. The central element is the actual LED (light emitting diode), a specially doped semiconductor that transforms the electrical energy into visible light. This process takes place in a very narrow area in the centre of the semiconductor, the so-called junction area or junction. The LED itself features two electrical connections and can be fixed onto a thermally conducting carrier material to dissipate the heat occurring during operation. These components are protected by a robust housing that is covered above, i.e. in the radiation direction, by a primary optical system (usually a small lens).

Coloured light

If the spectral composition of the light from various light sources is compared then major differences are seen. Candlelight for example contains an above average red component and is perceived as warm light, whereas the light from a fluorescent tube has a higher blue component and appears cooler. As most natural light sources emit a wide spectrum of various wavelengths, specification of a single wavelength is not suitable for characterising white light. More decisive is the ratio of the various spectral components. These specify the colour temperature with white light or the colour of coloured light.

Efficiency of LED

The light emitted from a diode is not the by-product of a thermal process as with incandescent lamps but is generated as part of an electrical reaction within the diode, with recombination of positive and negative charge carriers in the junction area of the semiconductor. The energy released is emitted as electromagnetic radiation in the visible range, meaning in the form of light. The efficiency of LEDs exceeds that of an incandescent lamp many times over. Around 50 % of electrical energy input is transformed by LEDs into light.

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Each and every one of us is familiar with the enlivening effects of light. It animates, activates and controls daily routines. Current surveys even confirm the positive effects of sunlight on our health and psyche. 

Artificial light though can also boost the well-being of people, enhance concentration and can be inspiring. Aimed at achieving the same benefits as sunlight, artificial light is far more than just a tool for lighting purposes.

The development of TRILUX LED

The systematic expansion of expertise and knowledge transfer, especially within the framework of the development of new technologies such as LED, is very important. This is why TRILUX is strongly involved in the networking of basis and application researchers, public institutes and standardisation boards. Cooperative projects in the LED sector are currently taking place with 3M, the Fraunhofer Institutes, the Federal Ministry for Education and Research, the Ilmenau Technical University, with OSRAM in the sector of OLED, and also with our subsidiary BAG in the area of light control. These projects are dedicated to future-oriented themes such as the research and develop ment of sustainable work and office concepts, a survey on dynamic light for office workstations of the future and interactive systems for lighting control.

TRILUX has been a member of Zhaga, a global board made up of various lighting companies, since February 2010. In view of the rapid and continuous development of LED technology, Zhaga draws up specifications that ensure the interchangeability of LED modules from various manufacturers. Zhaga concentrates on the mechanical, photometric, thermal and electrical compatibility of LED modules, systems and control gears.

Sustainability

Long-term thinking and acting has always been a fundamental component of our activities. Our aim is to offer sustainable and energy saving products and to produce these with a responsible handling of resources such as raw materials and energy. Thanks to LED technology our products have reached dimensions in terms of economy, environmental compatibility and energy efficiency that seemed impossible a few years ago.

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LED-Guide 2016

Download the current LED Guide as a PDF.

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