LED Lighting
Practically everyone has heard of the new LED bulbs that are coming out lately, but few know exactly what they are or what makes them different from other bulbs. In short, Light Emitting Diodes (LED) are bulbs without a filament, that are low in power consumption and have a long life span.
A Little History
In 1907, a British experimenter, H. J. Round, was the first to report of a light-emitting solid-state diode. Unfortunately, this discovery produced no practical use for many decades. In the 1970s LED indicator lights started to become commercially available for use in appliances such as TVs, radios, and telephones. Although these LEDs were bright enough to use as indicators, they were not able to illuminate an area. As the technology started to advance, the light output of LEDs increased, and have now become bright enough to be used for illumination.
Today, LED technology has provided us with LEDs which can be used in many lighting applications. We have LED flashlights, headlights, boat lights, and you can find many types of LED bulbs to replace the bulbs you have in your home.
How Are LEDs Different From a Regular Incandescent Bulb?
As we mentioned above, unlike ordinary incandescent bulbs, LEDs do not have a filament that will burn out. A LED is a type of diode that turns electrical energy into light. For those that don’t know, a diode is an electrical component that only works in one direction. Basically, an LED is an electrical component that emits light when electricity flows through in one direction, from the Anode (positive side) to the Cathode (negative side). They are illuminated solely by the movement of electrons in a semiconductor material, and they last as long as a standard transistor.
For a more technical explanation go here: http://electronics.howstuffworks.com/led1.htm
Lifetime of LED Lighting Products
The “useful life” of LED lighting products is defined differently than that of other light sources, such as incandescent or compact fluorescent lighting (CFL). LEDs themselves rarely “burn out” or fail. Usually it’s the electronics that power them that fail. Instead, LEDs experience ‘lumen depreciation’, whereas the brightness of the LED dims slowly over time. Unlike other type of lightbulbs, LED “lifetime” is established on a prediction of when the light output decreases by 30 percent. LEDs use heat sinks to absorb the heat produced by the LED and dissipate it into the surrounding environment. This keeps LEDs from overheating and burning out. Thermal management is generally the single most important factor in the successful performance of an LED over its lifetime. The higher the temperature at which the LEDs are operated, the more quickly the light will degrade, and the shorter the useful life will be.
How Are LEDs Powered?
All LED bulbs are powered by “drivers”. A LED Driver is an electrical device that regulates the power to an LED or string(s) of LEDs. The driver responds to the changing needs of the LED by supplying a constant amount of power to the LED as its electrical properties change with the temperature. The driver is so important because LEDs require very specific electrical power in order to operate properly. If the voltage supplied to the LED is lower than required, very little current runs through the junction, resulting in low light and poor performance. On the other hand, if the voltage is too great, too much current flows to the LED and it can overheat and be severely damaged or fail completely (thermal runaway). Some LED bulbs have the driver built into the bulb. Various light fixtures and light strip installations have the driver as a separate replaceable part.
Advantages and Disadvantages of LED Lighting
Like all technologies, LED lighting comes with its advantages and disadvantages. However, as you will see from the points below, the advantages far outweigh the disadvantages.
Advantages
- Have a relatively long-life expectancy as compared to other lighting sources (Source).
- Environmentally friendly – they don’t contain mercury or other harmful substances (Source).
- Energy-efficient (Source).
- Generate low levels of heat.
- Available in a wide variety of colors.
- Brighten immediately when switched on, making them ideal for traffic and signal lights (Source).
- Saves money since they have a longer lifespan and use less energy.
Disadvantages
- Possible color shift during the lamp’s lifetime.
- The lifetime of the lamp can be reduced in areas of high heat.
