How LED Lighting Works

In the lighting industry, right now there are two words that are dominating many of the illumination choices contractors and building owners are making right now -- energy efficiency.

 

After all, the more efficient a light is the longer it will last and the less energy it will need to use to offer high-quality light. All of these things will equal cost savings in the long run for everyone involved -- who would be upset with that?

 

In the world of energy efficiency lighting, right now LED lighting is quickly growing in popularity. Although before it was mainly used for applications like traffic lights and in electronic gadgets, advances in LED light technology have started to allow LED light to now be used in residential and commercial applications, making it a viable substitute for traditional incandescent light, as well as fluorescent lighting.

 

History of LED Light

LED light can trace its roots all the way back to 1907, when a scientist by the name of H.J. Round -- an assistant of inventor Guglielmo Marconi -- identified a phenomenon known as electroluminescence. This experience is both optical and electrical, and happens when an electrical current passes through a certain material, and that material illuminates because of it. In this case, Round was working with silicon carbide, which is the substance that created light when electricity ran through it -- the color of the light would change depending on how much voltage he used.

 

After that, it wasn't until the 1920s that more research was done on electroluminescence. This time it was by a Russian researcher by the name of Oleg Vladimirovich Losev, who in 1927 had his research published on his work with, again, silicon carbide and electroluminescence.

 

Although Losev did not invent the LED light, his research helped pave the way for those that did. That day finally came in 1961 by two American inventors from Texas Instruments -- Robert Biard and Gary Pittman. The duo invented the infrared LED by accident when trying to make something else. Here it was gallium arsenide (GaAs) -- a compound of arsenic and gallium -- that the inventors found would emit light when an electrical current was passed through it.

 

In 1962, Pittman and Biard filed their patent for their discovery, and they were given the first-ever patent for what we know today as the LED light. Then later that year, Texas Instruments began to manufacture LED products for commercial applications.

 

An interesting thing to note is that the LED light that Pittman and Biard invented was infrared -- that means no humans could actually see the light it was making. It was, again, in 1962 that the first visible light LED -- a red one -- was created, this time by Nick Holonyack at General Electric. Then in later years, other inventors created other color LEDs. For example, the yellow-colored LED was invented in 1972 by M. George Craford for Monsanto Company, in 1991 the white LED was developed by Naruhito Iwasa at chemical company Nichia, and in 1994 the blue LED was invented by Shuji Nakamura in Japan. 

 

How LED Light Works

So just how does LED light work?

 

In its simplest form, an LED -- or Light Emitting Diode -- is a type of semiconductor that has two terminals and is used to manage what direction light will go in. When an electrical current is run through the semiconductor (aka diode), it makes light.

 

To make the light magic happen, the LED uses a process called p-n junctions. One side of the diode is filled with semiconductive substances that have a negative charge, while the other side is also filled with semiconductive substances, but this time that have a positive charge. What is keeping these two sides apart is known as the p-n junction. Additionally, the p-n junction is what keeps the electrical current flowing in only the direction you need it to.

 

When an electrical current is passed through the diode, electrons are emitted by the material on the n-type side. Those electrons get moving, and travel over to the p-type side and literally "fills in" electron holes that are in the positive atoms there. When this filling in happens, those electrons lose some energy, which is released in the form of a photon of light.

 

How large the photo is expelled is determined by how much energy is released. And depending on the frequency of photon you get will regulate what color light you end up getting, or if the light can even be seen by humans. As we mentioned earlier, you can get infrared and red color LED by using gallium arsenide. If you want to result in a blue colored LED, you would use the compound gallium nitride. And for a white LED, you would use a man-made crystalline substance called yttrium aluminum garnet.

 

LED Lamps

So just how does all this work in an LED lamp?

 

Unlike a conventional incandescent light bulb, an LED lamp does not use a filament that when heated glows and emits light. Instead, one LED lamp is made of a bunch of small LEDs into a bulb product that can be screwed into a light socket, or a tube product that can be used to replace fluorescent lighting.

 

Generally speaking, an LED lamp can replace incandescent bulbs from 5 to 60 watts, and most use a base that makes it compatible with standard light bulb sockets. Additionally, some types of LED lamps can be dimmed, and others come in a variety of different color combination options.

 

For LED tube lamps, these can be used to replace fluorescent T8, T10 or T12 lamps, and are normally available in 2, 4 and 8-foot sizes. Some LED tubes can just be dropped right into existing fixtures, but others may require some rewiring so the ballast can be removed.

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