Efficient light guide for office luminaires and computer screens
In office luminaires and computer monitors, lateral LEDs feed their light into a light guide plate which reflects the light rays completely – in a sense, the light is locked up in the plate and can escape only at predefined places through carefully made imperfections. In most cases, these imperfections are implemented as white dots that are printed onto the plate. Specific arrangements make the light guide plate appear to emit a homogeneous light.
The new technology, developed by researchers from the Fraunhofer Institute of Production Technology in Aachen (Germany), is based on a different principle: In a hot-embossing process, the researchers first created a Master template which includes all imperfections. This metal master template serves as a kind of punch – it can be used to produce the guide plates in a die casting process or to impress the pattern in a roll-to-roll impressing process. The advantage is that while the "white dots" in the conventional technique provide a more or less omnidirectional radiation pattern, the new technique creates light dots that send out focused, unidirectional light. In addition, this technique is more energy efficient and cost efficient if applied in high volumes. The Fraunhofer researchers claim a cost advantage of up to 20 percent.
For more information contact christoph.baum@ipt.fraunhofer.de
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