LED - BASICS

LED LIGHTS – BASICS

A light-emitting diode (LED) is a semiconductor light source that emits light when current flows through it. LEDs create light by electroluminescence in a semiconductor material. 

                   
Electroluminescence is the phenomenon of a material emitting light when electric current passed through it. It essentially means that a material (in this case, the diode) casts light when power is applied to it. Electrons jump from one side (an electron-full side) to another (an electron-deficient side) across a junction (the “p-n junction”).

Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light (corresponding to the energy of the photons) is determined by the energy required for electrons to cross the band gap of the semiconductor. 

LED light fixture uses a small semiconductor crystal with reflectors and other parts to make the light brighter and focused into a single point.

LEDs are incorporated into bulbs and fixtures for general lighting applications. Small in size, LEDs provide unique design opportunities. Some LED bulb solutions may physically resemble familiar light bulbs and better match the appearance of traditional light bulbs. Some LED light fixtures may have LEDs built in as a permanent light source. There are also hybrid approaches where a non-traditional “bulb” or replaceable light source format is used and specially designed for a unique fixture. LEDs offer a tremendous opportunity for innovation in lighting form factors and fit a wider breadth of applications than traditional lighting technologies.

In LEDs, current increases very quickly as voltage increases. Small fluctuations in voltage can therefore damage them. A driver must therefore be employed to control the input power to the LED. The LED driver is an electronic circuit that keeps the current constant despite fluctuations in voltage so that the LED can be operated from any normal power supply. Drivers can also incorporate a dimming function so that a LEDs light output can be controlled to between 0% and 100%.

LED chips are small, point light sources that can be used singly or in a cluster of more than one chip. Around the LED chip or cluster, all kind of optical materials can be used to direct and screen the light. If LED chip with its driver, is encapsulated in a bulb with a conventional lamp base, we have a direct replacement for an incandescent lamp, so called LED lamp.


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