LED (Light Emitting Diode)

What is an LED?

An LED (Light Emitting Diode) is a tiny chip of silicon made to produce light in a variety of colors including red, green, yellow, and blue.

What's the difference between LEDís and other types of bulb technology?

LED's are significantly less expensive than incandescent lamps. LED's are also less expensive than monitors over a life of 10 years. LED's have an expected life of more than 100,000 hours or from 11 to more than 20 years. The longer life dramatically lowers maintenance expense compared to monitors or lamps. LED's need very little power and generate less heat than other light sources. Less power and heat mean less operating and maintenance costs. LED's are small and lightweight. This lowers the cost of the enclosure and installation.

What is a discrete LED?

Individual LED's are inserted one at a time into a circuit board. The anode and cathode lead wires are then individually soldered to the circuit board. A pixel may be composed of either one LED or several LED's installed close together. LED's grouped together appear as a single pixel when all LED's in the group are lighted at the same time. A group of LED's in a single pixel may contain more than one color LED. The various colors are produced by turning on the appropriate combination of LED's in the pixel.

How does multiplexing affect LED brightness?

The output intensity or brightness of an LED is measured in millicandela. The most common technique used in indoor displays to get the greatest range of brightness is called "multiplexing". The LED's are strobed rapidly, faster than the eye can detect, one at a time. This method limits the brightness of each pixel since the pixel is only turned on for a sequence of brief instances. When an LED is latched on, it is lighted continuously until it is turned off again. This produces brighter pixels. Data block modules can only be multiplexed; discrete clusters are usually latched.

How do clusters enhance LED brightness?

When a brighter pixel is needed, multiple LED's are assembled in "clusters" of LED's that together form one pixel point when they are lighted. Multiple LED's are connected to a molded cup which is then filled with clear epoxy to hold the LED's in place. Clusters may contain one color LED or in a multi-color application the cluster may contain a combination of different LED's.

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