What is LED
LED stands for Light-Emitting Diode. That is, simply, a semiconductor device that converts electricity to light by using the movement of electrons. There are many consumer advantages to LEDs over incandescent or fluorescent light bulbs. LED lights consume much less energy. They are 300 percent more efficient than a compact fluorescent light (CFL), and 1,000 percent more efficient than an incandescent bulb. They have a very long life, about 50,000 hours of use at 70 percent of their original power. (LEDs don't burn out or flicker, they simply fade.) This works out to eight hours a day for 13 years at 70 percent power. A typical 60-watt incandescent bulb may last about 1,000 hours. LED lighting contains no mercury or other toxins. LEDs emit no ultra violet (UV) light, so they don't attract bugs. They don't generate heat, so they are cool to the touch. They don't generate radio frequency waves, so they don't interfere with radios or television broadcasts. They also are resistant to vibrations and shocks. Their directional nature means they are best used under kitchen counters, in stairways and hallways, or as reading lamps, landscape lighting, and night-lights.
Features and Benefits of LED
The inherent features of LED decide it to be the best alternative to conventional light source, and provide a wide range of application.
1. Small Size :
A LED is essentially a tiny chip ,about 4.5mm, encapsulated in an epoxy resin enclosure, so it can be extremely small and light.
2. Low Power:
Consumption: Generally a LED is designed to operated at 2-3.6v,0.02-0.03A current, that mean, it needs no More than 0.1w to operate.
3. Long lifetime:
Operating at a desired rated voltage, current and environment, LEDS enjoys a long life of up to 100,000hours.
4. High luminous efficiency and low heat emitting :
Due to the special materials that used to make LEDs, during electrons transition, LEDs mainly emit electromagnetic energy in the visible parts of spectrum, unlike the incandescent filaments heated, which emit a lot of electromagnetic energy in the infrared pat of the spectrum which can’t be seen but is felt as heat. That is to say .LEDs are of high Luminous efficiency and low heat emitting .The best LED in the market now emits 150LM/w, which is almost tenfold as efficient as an equivalent tungsten-filament light bulb.
LEDs are made from non-toxic material, unlike the fluorescent lights with mercury that will pose a pollution danger. LEDs can be recycled too. Unbreakable: The light-emitting device of a LED is completely embedded in an epoxy resin enclosure which is much more sturdy than the bulb and fluorescent tube;there are no loose and moving parts within the solid epoxy enclosure. This makes LEDs virtually indestructible.
The application of LED
LED’s proprietary characteristics above mentioned determines their ideal suitability in a wide range of application.
1. Decorative lighting
Due to the rich variety in colors, small size, durability, energy savings, LEDs are perfect light source for decorative application. Attached on a PCB, flexible cable, or other desired materials; LEDs can be used for light source of channel letter, signs, border light, light tube and so on.
With the advance of the white light LED technology, an array of white light LEDs assembled in a certain way are now bright enough to be used for domestic illumination, such as light, table lamp, and garden lamp etc.
A typical application of LEDs is for message display or large-scale display screen, which are popularity used in sport fields, airports, business centers and so on. The largest LED display in the world is 36mm high, at Times Square,Manhattan.
4. LCD backlight
Because of LED’s small size and low power consumption, they are perfect light source for LCD backlight.
Monochromaticity is the inherent property of LEDs. They emit a pure color in a narrow frequency range. The color emitted from a LED is identified by peak wavelength(Ipk) and measured in nanometers(nm).Peak wavelength is a function of the LED chip material, the composition of the different materials determines the wavelength and therefore the color of light emitted.
As we know, white color is a combination of all colors. But eye does not require a mixture of all the colors of the spectrum to perceive white light.A mixture of three primary colors(red, green, blue) can be well enough.
Based on this principle, many solutions have been proposed to fabricate white color LEDs. The typical one is to bury a GaN type blue LED having an InGaN active layer into a YAG pond emitting yellow fluorescene.
6. Intensity an View Angle
LED light output varies with the type of chip, encapsulation, and other variables .But there is no consistent international criterion for LED brightness measurement. Generally, the amount of light emitted from a LED is quantified by a single point, on-axis luminous intensity value(IV), and is specified in millicandela(mcd).
A LED with higher luminous intensity value does not mean that it has higher total light output. To measure the total light output, the viewing angle must be taken into account too. LED viewing angle is also a function of the LED chip type an the epoxy lens that distributes the light, LEDs with different chips and epoxy lens will have different viewing angle. If two LEDs have the same luminious intensity value, the lamp with the larger viewing angle will have the higher total light output.
LED advantage --- real environment-protection lighting
1. Energy Saving:
almost all energy can be transferred to luminaries. Up to 90% energy saved compared to traditional Tungsten Lamps and Compact Fluorescent Bulbs. The LED product is an extremely high-powered transformation, durable, and it will reduce future electricity cost.
Long-lasting: The LED product can last up to 100,000 hours without reduced brightness. This is 10 times longer than a traditional Tungsten Lamp and Quartz lamp, and more much durable than a Compact Fluorescent Bulb, which gets a maximum of 8000-15000 hours.
Safety: LED doesn’t contain Mercury or Tungsten and it is difficult to be damage or break. Therefore LED will not leak electricity and pollute the environment. Moreover, it is the most environmentally friendly luminary and has an extremely low maintenance cost
2. Environment Protection:
LED is Cool-Light Illuminating System and therefore it will not produce extra heat, enabling the user to use less air-conditioner and save cost. This also reduces carbon emissions