LED Lighting Technologies
Light Colour of the LED
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  The Colour
of the LED-Light
We inform you about the light colour of white LEDs - how it is generated, what is possible with LEDs and how it influences human living.  
  How is the Light of White LEDs Generated?

In the picture on the left side you see a typical spectrum of a white LED. The light colour is indicated below the spectral curve for better understanding - starting from blue to red.

A LED is built from a semiconductor chip transmitting blue light. To get white light a special phosphorous cover is positioned above this chip to convert a part of the blue light to other colours. This behaviour is demonstrated in the picture on the right side - with green to red colour under the spectral curve.

In total a colour mix (including the not converted blue portion) is emitted which is recognized as white colour.

The Different "White" Colours

On the left side you see the CIE 1931 color space of the International Commission on Illumination (CIE Commission internationale de léclairage). The pure colours (e.g. the light from coloured LEDs) are localized at the boder of the coloured area - together with it's wavelenght numbers. Inside the area are the mixed colours. In the center is the "White Point" (D50).

The insert is the enlarged black body curve . You can understand this curve in the following way: a black body emits a colour dependent on its temperature. This colour ranges from light blue at 10000K temperature to orange at about 2000K. And this curve goes throuch the socalled white point.

For example, a light bulb has a light temperature of about 3000K and is recognized as warm light (as the temperature of its tungsten filament is around 3000K). On a sunny day we have a light temperature of around 6000K (D65). The D50-point is the nomative white point.

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  White LEDs

The figure on the left shows the spectra of different white LEDs (relative amplitudes as a function of the wavelength):

red: warm white LED - 3000K - small blue potion

green: neutral white LED - 4500K - middle blue portion

blue: cold white LED - 6000K - large blue portion

  The Circadiane System


(Acc. to Prof. P. Marx, Presentation TSB-Berlin, November 2012)

The sensitivity of the eye is centered at about 550nm (green light. green curve in left figure). However, there is another sensor system inside the eye, the Circadiane System. This system has a maximum sensitivity at around 450nm (blue). The Circadiane System controlls the biological clock (via Melatonin generation). Simply told, we get tired when the sun sets and the light becomes more and more orange (reducing blue light).

If using more blueish light (e.g. cold white LEDs), you can circuimvent fatigue as proven becasue of reduction of Melatonin production. Thus you can work more concentraded for longer time.

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Using our LED-Luminaires you can adjust the light colour you want and improve your working convenience.

  Impact of illuminance on human working efficiency

Illuminance (lux) 200 500 1000
simple work 5% 8% 10%
difficult work 20% 35% 45%

(Acc. to Prof. P. Marx, Presentation TSB-Berlin, November 2012)

The table beside gives an overview about the improvement of human working efficiency through increasing illuminance. The percentage numbers indicate the improvement relative to a illuminance of 100 lux.

Therefore our LED-Luminaires have much more light power than requested for standardized working illumination (500 lux).