LED lighting is becoming more prominent in everyday items. You see them in vehicles on the roads, stop lights, and even in household appliances. With how often we see LED lights it is surprising how little we actually know about them. We here at Falconer Electronics Inc. work with LEDs everyday so we thought it would be a great opportunity to give out our knowledge on the subject.

What is an LED?

LED stands for Light-Emitting Diode. What does “Light-Emitting Diode” mean exactly? More specifically LEDs are semiconductor diodes. Semiconductor diodes are small electrical devices that allow electrical current to flow in a single direction.

The diagram below shows how these LEDs actually emit the light we see.  

LED                 

When positive particles meet with  negative particles within the semiconductor LED light is created.

How are there different colors?

Inside the semiconductor there are “energy bands” that contain the positive and negative particles. Since a separation of these energy bands determine the light particles that will be seen. These light particles and separation of energy bands are what determine the wavelength of light that comes from the LED which is what gives them their colors.

The use of different material within the semiconductor mixed with different energy band gaps will lead to the emitting of different colors of light. Also noteworthy is that there no true white light in LEDs.  A covering over the natural yellow of the phosphor or the combination of colored lights creates the white color that is often associated with certain bulbs.

Below is a list of the different materials of semiconductors and what colors of light they give off:

  • Indium gallium nitride (InGaN): blue, green and ultraviolet high-brightness LEDs
  • Aluminum gallium indium phosphide (AlGaInP): yellow, orange and red high-brightness LEDs
  • Aluminum gallium arsenide (AlGaAs): red and infrared LEDs
  • Gallium phosphide (GaP): yellow and green LEDs

LEDs and Heat

LEDs do not give off heat like typical incandescent or halogen bulbs. Also LED bulbs include a heat sink in their design. A heat sink is a device that absorbs the heat and keeps the LEDS from burning out because of overheating.  In addition, by drawing the produced heat away from the LED and taking the heat onto itself heat sinks absorb this excess heat. However not all heat sinks look alike just like the actual LED bulbs.

If an LED’s heat sink isn’t functioning properly it can lead to some issues due to:

  • LEDs can have shorter life spans
  • LEDs can begin to flicker after as short a time as one year
  • A colored bulb can see a change in the hue that is being seen
  • The light can begin to look dim and therefore not light up a room or device as is needed
  •  Possibility of uneven lighting given off 
  • Most notably these malfunctioning bulbs can continue to use power even when they are not in use

Coming Soon:

The History of LEDs, Environmental Benefits Using LED Lighting, Falconer Electronics Produces LED Lighting, and Lighting with LEDs vs. Incandescent

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Resources:

http://www.lrc.rpi.edu/programs/nlpip/lightinganswers/led/whatisanled.asp

http://www.ledsmagazine.com/articles/2004/01/what-is-an-led.html

https://www.energystar.gov/products/lighting_fans/light_bulbs/learn_about_led_bulbs

 

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