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LED luminaires and colour perception

LED luminaires and colour perception


The focus of the LED application has leaped from being merely more efficient to more and more on exact colour rendering and on the development of the spectra and developing high-quality LEDs that fulfil even the most sophisticated requirements.


The colour rendering quality that has to be achieved in working spaces can be found in DIN EN 12464. The ideal value is the value in daylight, Ra=100. In interior rooms,lamps with a colour rendering index of at least 80 have to be used. At fixed workstations that are used all the time, an even more reliable recognition of all colours should be ensured by suitable measures.


Colour-fast, even with a limited spectrum

In the current state of the art, the colour rendering of LEDs is below 100. The wavelengths of the different semiconductor materials that are used in the different LEDs are near the curved outer edges of the two-dimensional CIExy colour space By combining an LED with a modern luminescent substance, a very broadband white light with light rendering values of more than 90 can be emitted by now.


Appropriate selecton of the white light variant

However, it is not only the colour rendering value that is important for white light, but also its so-called colour temperature. The concept of the colour temperature, specified in Kelvin, is derived from the thermal radiation of an ideal-typical black body that does not reflect visible radiation.


For the so-called neutral white, EN 12464 defines colour temperatures ranging from 3300 K to 5300 K, calls temperatures below 3300 K warm white and such that have more than 5300 K cold white.


R. STAHL generally offers three colour temperatures for all products – besides neutral white with 5000 K, it offers a cold white of 6500 K and a warmer variant with 4000 K. The colour rendering index Ra always is 80 or more and thus complies with the requirements on interior rooms specified in DIN EN 12464-1.


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LED luminaires and colour perception by R. STAHL