Light Emitting Diode (LED) generates light in a semi-conductor
material, which is an electronic component. Using the right materials, a
diode may produce visible light of various wavelengths.
White light is created by either using a blue diode or “chip” and
adding yellow phosphor on top of it or mixing light from one red, green
and blue diode (RGB). The use of phosphor conversion is the most used
method in the lighting industry, due to its high efficacy and flexible
production method. The phosphor can be added directly onto each diode or
as a remote phosphor plate on top of a mixing chamber. This method
creates a particular colour spectrum, or spectral power distribution for
the LED depending on the phosphor layer.
LED is not a new
invention and most of us are used to LED`s being red or green signal
markers on your Hi-Fi or television set. These are so called – low-power
LEDs. During the last couple of years “high
power” LEDs, i.e. LEDs operating at powers of around 1 W, have reached a
level of cost and performance that make them attractive to the general lighting
Market studies forecast that in 2020, close to 50 % of
all new and replacement light source unit sales will be based on LEDs.
Since LEDs are more expensive than conventional lighting, the value of
the LED sales will be even higher.
Currently, the efficacy levels are at around 160 lm/W, coming out from the light source. The LED itself is expected to yield around 200 lm/W within the next ten years (Sources: McKinsey and Osram).
spectral power distribution (how much light that is emitted at each
wavelength) of the LED mirrors the blue light from the chip and the
figure shows the development in efficacy (lm/W) over time for
conventional and LED light sources. Whereas fluorescent tubes are
expected to reach a maximum of 120 lm/W in 2020, LEDs may reach around
200 lm/W (Source: Osram)|