Understanding LEDs

LEDs are light emitting diodes. These are electronic components that convert electrical energy directly to light through the movement of electrons within the material of the diode. LEDs are important because due to their efficiency and low energy, they are replacing most conventional light sources.

The term solid state lighting is used because the electronics produce light directly from solid materials in which the electrons are embedded. Other light source technologies, eg. the fluorescent tube requires a gaseous discharge medium to initiate production of light.

The junction temperature is critical in LED lamp or luminaire design. It is the LED’s active region; the point at which the diode connects to the base. This is where the electrons jump between the two semiconductors to produce photons. A low junction temperature helps LEDs to produce more light also reduces lumen depreciation. Junction temperature is affected by the driver current, the thermal path, and the ambient temperature.

LED technology is constantly changing. Rapid innovation continues to improve the performance of LED on an almost daily basis. Future-proofing of LED modules allows luminaire manufacturers to switch from one generation to the next improved generation without major retooling or changes in luminaire design, offering backward compatibility with drivers.

LED chips are mass produced in millions and there are inevitably slight differences in color appearance and light output. Binning is way of sorting the chips so that all the LEDs from one particular bin look the same and have similar light output.

A Light Engine is the LED equivalent of a conventional lamp. It normally consists of a LED chip mounted on a circuit board that has electrical and mechanical fixings, meaning it is ready to be fixed in the luminaire.

The driver is often the critical component in a LED luminaire or lamp, more so than the LED chip itself. The driver has to be matched to the power requirements of the LED chip.

The power factor is the active power divided by the apparent power (i.e. product of the rms input voltage and rms input current of a driver).

The power factor correction is an electronic device, such as an LED lighting fixture, a system of inductors, capacitors, or voltage converters to adjust the power factor of electronic devices toward the ideal power factor of 1.0.

Although the initial cost of conventional light sources is less than LEDs, the operational and maintenance costs of LED are significantly lower. LEDs have a longer life, reduced maintenance and lamp replacement cost.  Because LEDs need to be replaced less frequently, the owner spends less on new lamps and the labour needed to change them. LEDs also consume less energy; therefore, the overall cost of a LED system can be significantly lower than that of conventional lighting systems.