LED is an abbreviation of the english name Light Emitting Diode, in our country the phrase LED diode is used, although the term "diode" is actually contained in it twice. The colloquial term led is also often used. An LED is an electronic component containing a P-N semiconductor junction. Its illumination is caused by a phenomenon called electroluminescence; if an electric current passes through the junction in a permeable direction, light with a narrow spectrum (monochromatic) is emitted.
The colour of the LED light depends on the chemical composition of the semiconductor used. Red LEDs were the first to be produced, then gradually green and yellow LEDs were added, and lastly blue LEDs were designed, which subsequently enabled the production of white LEDs.
We'll talk more about the white LEDs. LED cannot emit white light, but developers have learned to elegantly circumvent this disadvantage. They use a blue light-emitting diode and apply a yellow powder called a phosphor in front of the emitting part. This is mixed from precious metal compounds and its function is to convert some of the blue light emitted by the LED into yellow light. Mixing the remaining blue light with the converted yellow light produces white light.
LEDs have already replaced conventional light bulbs in most products. There are several reasons for this, first of all we can mention efficiency. While in a filament bulb most of the electrical power is converted into heat, LEDs are much more efficient and light up several times more for the same wattage. The second great feature is the lifetime. In incandescent bulbs, the filament gradually thins until it eventually burns out or breaks due to a shock, in the case of a led there is nothing similar, the lifetime is limited by the aging of the semiconductor and the led gradually loses luminous flux, but this happens very slowly in quality products, sudden end is rare.
Another good feature is the absence of harmful types of radiation, in the light of the led we do not find IR or UV radiation. The stability of colour temperature (chromaticity temperature) at different supply currents is also pleasant. If we reduce the supply current of the bulb, not only does the light fade, but at the same time it shifts to the red spectrum. With LEDs, only the luminous flux decreases, the colour of the light does not change.
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Of course, LEDs also have disadvantages, higher temperatures significantly shorten their lifetime and they shine less. High-performance LED chips must therefore be placed on a heat cooler to dissipate waste heat and prevent the chip from overheating. Another disadvantage is the frequent need for electronic power regulation, which, especially for powerful LEDs, ensures the necessary size and stability of the power supply current.
The use of modern LEDs is really very wide, they can be found in virtually every electronic product, most often as a signal light or in the backlighting of displays. Powerful LEDs, often called LED chips, are a separate chapter. These large-area semiconductor LEDs are designed to produce intense, usually white light. These types of LEDs can be found in flashlights, LED bulbs, TV screen backlights and other products with a need for a strong light source.
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