Thứ Ba, 31 tháng 7, 2012

Optical WLAN uses LED light for up to 800 Mbit/s networking

Công ty cổ phần future light chuyên phân phối sản phẩm đèn led,đèn sân khấu,...den trang tri...

If you've followed the latest trends in environmentally conscious lighting at all, you know that LED light bulbs are going to be replacing your incandescent and CFLs in the next few years. But how exactly does an LED light bulb work?

 

More and more, the advantages of using LED lighting are becoming clear.
  • Eighty percent more efficient than incandescent
  • Safer. No mercury, unlike CFLs
  • A pleasant, warm light
  • A lifespan of more than 30 years
  • Very little energy is wasted as heat. 

 

What is it about an LED light bulb that allows it to do all of this?
History
Oh no. Not history! I'll keep it brief. LED stands for Light Emitting Diode and it was invented in 1962. At first LEDs could only emit a red light, like the ones you would find in an old digital alarm clock. As time went on, they discovered how to use the diodes to emit nearly the entire light spectrum. Today they are used in everything from TV screens, to small electronics, to light bulbs.
How the LED works
Magic. Ok it's not magic, but I'm a writer not an engineer, so I'll do my best to give you the real answer. The LED (light emitting diode) works by using an electric current traveling through a negatively charged anode to a positively charged cathode. What is this science fiction you ask? Basically, a diode only allows an electric current to travel in one direction. This current causes electrons to recombine, which releases energy in the form of photons, AKA light.
Why LEDs last so long
Unlike an incandescent light bulb, there is no filament, so there is almost nothing to burn out. The LED is a simple electronic circuit and has no moving parts, and is a solid state device. It's essentially a small circuit like you might find in a computer chip. Without any components to burn, or wear out from movement, an LED can last a nearly infinite amount of time.
Why LEDs Are So Energy Efficient.
This question also actually relates to why an LED runs so much cooler than a regular light bulb. To understand we need to see how an incandescent works. An incandescent light uses a strong electrical current to heat a thin metal wire, called a filament. The metal grows so hot that it begins glow. The metal cannot ignite because it is contained inside a vacuum in the bulb, however it does give off a tremendous amount of energy. However, only about 20 percent of this is energy is in the form of light, the rest is almost all wasted as heat.
As mentioned above, LEDs do not use heat to produce light. Instead it uses a small electrical current to excite electrons, which in turn release energy as light. Only a very small fraction of the energy is lost as heat.
Hopefully this helped explain to you how an LED light bulb works. It's not magic after all. 

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