LED
Technology Explained
A
light-emitting diode (LED) is an electronic light source. The
LED was introduced as a practical electronic component in 1962.
All early devices emitted low-intensity red light, but modern
LEDs are available across the visible, ultraviolet and infra
red wavelengths, with very high brightness.
LEDs
are based on the semiconductor diode. When the diode is forward
biased (switched on), electrons are able to recombine with holes
and energy is released in the form of light. This effect is
called electroluminescence and the colour of the light is determined
by the energy gap of the semiconductor. The LED is small in
area (less than 1mm²) with integrated optical components
to shape its radiation pattern and assist in reflection.
LEDs
present many advantages over traditional light sources including
lower energy consumption, longer lifetime, improved robustness,
smaller size and faster switching.
Operating
Life
Because LEDs are solid-state devices they
are not subject to catastrophic failure when operated within
design parameters. LEDs are designed to operate upwards of 60,000
hours at 25°C ambient temperatures. Operating life is characterised
by the degradation of LED intensity over time. When the LED
degrades to half of its original intensity after 60,000 hours
it is deemed to be at the end of its useful life although the
LED will continue to operate as output diminishes for up to
100,000 hours.
