What is LED ?

LED stands for Light Emiting Diode, and it is a semiconductor device able to generate light. Normally the light generated by an LED is one of the following colors:

- green

- red 

- yellow

- blue

The white light can be obtained in 2 ways:

- starting from a blue LED  used as a light source. The blue light generated by the LED is forced to cross a yellow phosphor layer. The result is a white light. In practice, the simiconductor LED chip is encapsulated in a yellow phosphor layer to obtain an LED ball which will generate white light.

- mixing the Red, Blue and Green lights generated by 3 individual LEDs in a certain proportion. This is called an RGB (red-green-blue) type of LED, and it is widely used in color LED technics.

Today, the most common method to obtain white light is the first one. 

Depending on the composition of the yellow layer, different color temperatures can be obtained, ranging from 2600K (called very warm white) to 6500K (called cool white).