LEDs

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What is LED?

LED is a light emitting semiconductor diode that emits light in forward direction or in the direction it is pointed towards. LED's are most often used in the form of an indicator light in electronic devices, traffic signal lights, musical instruments and dashboards in cars and in houses etc. The color of the light produced by LED depends on the composition of the semiconductor material used out of which producing a blue color light is the most difficult process. The nature of the light emitted can be visible, infrared or ultraviolet. You may also want to read about OLED, the organic LEDs.


LED bulbs facts - What is a LED light bulb?

LED light bulbs are made by arranging identical light emitting diodes closely to form the shape of a light bulb. The visible light thus produced closely resembles day light and is very capable of replacing the traditional light bulbs such as incandescent lightbulbs and compact fluorescent lamps.


Lifespan of a LED light bulb?

Most modern LEDs are undergo superior design and manufacturing process that gives them a lifespan of up to 100,000 hours, compared with 10,000 for a compact fluorescent and 1,000 for an incandescent bulb. Lifespan of a LED bulb could dramatically come down due to the amount of heat a LED produces. This directly depends on die temperature and ambient temperature of the LED. Some LED lightbulbs show sign of age after a couple of years of use and may produce only 50% of the light output when compared to what it used to produce when it was new.


Power consumption of LED light bulbs?

Most modern LED operate in a range of 2 to 4 volts and consume anywhere between 350mA and 1500mA. The power consumption varies from manufacturer to manufacturer and also because of the purpose for which the LED was designed. Another factor that affects power consumption of LEDs is for the fact that LEDs can not be dimmed. Now a days using latest of the LED manufacturing technology, manufacturers are able to produce LEDs that are not only super bright but also consume less power while producing light of higher intensity.


Power savings by using LED Traditional incandescent lightbulbs wastes upto 80% of its energy in the form of heat that they produce. LED lightbulbs on the other hand save that energy since heat emission is minimal. For example, you may replace a 40 watts standard light bulb with a high power 4 watt LED bulb that emits same light output. This makes a strong case for using LED bulbs at home.


Benefits of using LED light bulbs over standard light bulbs?

Power consumption of LED light bulb is only 10% of that of the standard light bulb.LED light bulbs withstand great amount of vibration, shock and temperature variations.LED light bulbs are 10-60 times more energy efficient than incandescent lightbulbs.Incandescent lightbulbs produce light that flickers whereas LED light bulbs produce flicker free light.LED bulbs can produce many rich and vibrant colors when compared to incandescent lightbulbs.


Fast facts about LED light bulbs and incandescent lightbulbs?

  • According to the Clean Energy Act of 2007 incandescent bulbs that produce 310 - 2600 lumens of light are banned.

  • This exempts light bulbs that use less than 40 watts or more than 150 watts of energy.

  • Australia has announced that it will ban use of incandescent bulbs and New Zealand is considering similar move to ban use of incandescent bulbs in its country.

  • Canada has plans to ban use of incandescent bulbs by 2012.

  • The European Union has proposed a ban on incandescent light bulb that bans production of the incandescent light bulbs.

  • Government of India is considering similar measures to ban production and use of incandescent light bulbs.If the entire USA switches to LED bulbs, it can effectively reduce its power consumption by almost 30%.

  • LEDs Technology: Light-emitting diodes (LEDs) differ from other light sources, such as incandescent and fluorescent lamps, in the way they generate white light. Unlike incandescent, fluorescent and HID sources, LEDs are near-monochromatic light sources. An individual LED chip emits light in a specific wavelength. This is why LEDs are comparatively so efficient for colored light applications. In traffic lights, for example, LEDs are rapidly replacing the old incandescent + colored filter systems. Using colored filters or lenses is actually a very inefficient way to achieve colored light. For example, a red filter on an incandescent lamp can block 90 percent of the visible light from the lamp. Red LEDs provide the same amount of light for about one-tenth the power (12 watts compared to 120+ watts) and last many times longer. However, to be used as a general light source, "white" light is needed. LEDs are not inherently white light sources.


    COMMON LED TYPES & PACKAGES

    LEDs come in two basic categories:


    Low power LEDs commonly come in 5 mm size, although they are also available in 3 mm and 8 mm sizes. These are fractional wattage devices, typically 0.1 watt, operate at low current (~20 milliamps) and low voltage (3.2 volts DC), and produce a small amount of light, perhaps 2 to 4 lumens.


    High power LEDs come in 1-3 watt packages. They are driven at much higher current, typically 350, 700, or 1000 mA, and—with current technology—can produce 40-80 lumens per 1-watt package.


    High power LEDs come in many different shapes and sizes. Some current products from the leading LED manufacturers are shown below.


    Source DOE - www.netl.doe.gov