LED

Nov 18th, 2011 | Posted by | Filed under LED Light

An LED lamp (LED light) is a solid-state lamp using light-emitting diodes (LEDs) as the supply of light. The LEDs involved might be conventional semiconductor light-emitting diodes, organic LEDs (OLED), or polymer light-emitting diodes (PLED) devices, although PLED technology is not currently commercially accessible.

Since the light creation of individual light-emitting diodes is less space-consuming than incandescent and compact fluorescent lamps, multiple diodes will often be used together. In recent times, as diode technology has improved, high power light-emitting diodes with higher lumen output are responsible for it possible to change other lamps with LED lamps. One high power LED chip utilised in some commercial Leds can emit 7,500 lumens for the electrical power consumption of 100 watts. LED lamps can be done interchangeable with other different types of lamps.

Diodes use household power (DC) electrical power; for their services from standard AC power they might need internal or external rectifier circuits. LEDs are damaged by operating at high temperatures, so LED lamps typically include heat management elements including heat sinks and cooling fins. LED lamps offer long service life and energy efficiency, but initial pricing is higher than those of fluorescent and incandescent lamps.
General-purpose lighting needs white light. LEDs emit light in a small band of wavelengths, emitting light of an color characteristic of the power bandgap of the semiconductor material used to produce the LED. To emit white light from LEDs requires either mixing light from red, green, and blue LEDs, or with a phosphor to convert some of the light to colors.

The first method (RGB-LEDs) uses multiple LED chips, each emitting another type of wavelength, in close proximity to create the broad spectrum of white light. The luxury of this method is that the concentration of each LED is often adjusted to “tune” the of the light emitted. The key disadvantage is high production cost. The of the light is often changed dynamically by adjusting the facility supplied to the different LEDs.

Your second method, phosphor converted LEDs (pcLEDs) uses one short wavelength LED (usually blue or ultraviolet) in conjunction with a phosphor which absorbs a small piece of the blue light and emits a broader spectrum of white light. (The mechanism is just like the way a fluorescent lamp emits white light at a UV-illuminated phosphor.) The major advantage would be the low production cost, and CRI (color rendering index), although the phosphor conversion reduces the efficiency on the device. The character in the light cannot be changed dynamically. Time frame cost and adequate performance helps it be the most widely used technology for general lighting today.

An individual LED is a low-voltage solid state unit and cannot be directly operated on standard high-voltage AC power without circuitry to regulate the voltage applied along with the current flow with the lamp. In principle a set diode and resistor could be familiar with control the voltage polarity in order to limit the current, but this may be very inefficient as most of the applied power could well be dissipated by the resistor. A series string of LEDs would minimize dropped-voltage losses, only one LED failure would extinguish the full string. Paralleled strings increase reliability through providing redundancy. In practice, three or even more strings are usually used. Being useful for illumination many LEDs must be placed close together inside of a lamp to combine their illuminating effects because, since 2011, the largest available LEDs emit simply a small fraction of the light of traditional light sources. With all the color-mixing method a uniform color distribution can often be difficult to achieve, while the arrangement of white LEDs will not be critical for color balance. Further, degradation of various LEDs at various times inside of a color-mixed lamp can lead to an uneven color output. LED lamps usually include things like clusters of LEDs inside a housing with driver electronics, a heat sink, and optics.

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