Basic principles of LED (Light Emitting Diodes)

• An LED consists of several layers of semiconducting material
• When an LED is operated with DC voltage light is generated in the active layer
• The generated light is radiated directly or by reflections
• In contrast to lamps, which emit a continuous spectrum, an LED emits light in a certain color
• The color of the light depends on the used material
• Two systems of material (AllnGaP and InGaN) are used in order to produce LED with a high luminance in all colors from blue to red and also in white (luminescence conversion). Therefore different voltages are necessary in order to operate the diode in conducting direction 

The production of white light

To produce white light, the light of blue LEDs is passed through yellow phosphors. The composition of the phosphor determines the light color.

The Chip Level Coating (CLC) process developed and patented by OSRAM ensures a degree of homogenity in the light produced that other processes cannot achieve.

By selecting appropriate white LEDs, it is possible to offer LED systems with the same light colors as fluorescent lamps (Warm White, Neutral White and Daylight).