LED - A New Form of a Light
What is an LED?
LED stands for Light Emitting Diode. A Diode is an electrical device that restricts current flow chiefly to one direction. Diodes are used in many electrical devices such as computers and audio equipment. A Light Emitting Diode is a special type of Diode that emits light when electricity is passed through it.
What makes an LED work?
Inside each LED is a small bit of chemicals. When electrons are passed through it, it emits light.
By changing this chemical compound, you can in effect change the wavelength emitted – infrared, red/green/blue (RGB), near ultraviolet, etc. By combining red, green and blue (RGB) LED’s you actually see a white light. Hence the method is called multi-colored white LEDs or RGB LEDs.
|RGB LED||White LED|
Another method to produce white light involves coating an LED of one color (usually blue) with phosphor of different colors to produce white light. The resultant LEDs are called phosphor-based white LEDs.
How is an LED different from a typical light source?
An LED is a diode, meaning that it is polarized (one end is positive and one end is negative). By convention, current can only go from the anode (positive end) to the cathode (ground, or negative end). Therefore the LED does not “like” and alternating current that alternates directions, but “likes” a nice steady current source. This means that using an LED is not as simple as changing a bulb. It requires electronics to change the normal AC (Alternating Current) into a steady direct current (DC) with a low voltage.
LEDs can be said to be the digital version of light as opposed to traditional light sources, which could be said to be analog. Thus LED’s are much easier to manipulate, can change colors and intensity with an electronic controller and are adaptable to many, many different applications.
What is so special about an LED?
- LEDs require lower power than traditional lighting sources to emit light. For example it takes about 10 watts to power an LED that is equal to a 60-watt incandescent bulb. The same light from a fluorescent takes 40 watts. The chart below shows a comparison of 5 different light source for lumens (a measure of light output) per watt (a measure of energy consumption).
- LED’s are directional – only putting light where it is directed, resulting in higher efficiency.
- LED’s have an exceptionally long life. An incandescent bulb may last about 1000 hours or less. A fluorescent tube should last 20,000 hours. A properly engineered LED will last 50,000 hours or more.