What are they?
LED light bulbs or lamps utilize light-emitting diodes in order to produce light. LED is a “solid-state” technology, which means that the materials used to generate the light are encased within a solid material. Practically, this translates into a lamp with a rated life much longer than those using non-solid-state technology (such as incandescent, halogen, and fluorescent). Solid-state lighting is also much less susceptible to failure due to shock or vibration.
Where did they come from?
General LED technology has existed for over forty years. The first visible-spectrum light-emitting-diode was invented in 1962 by Nick Holonyak, Jr.,
who was working as a consulting scientist for General Electric at the time.
However, several factors kept the technology from advancing into practical lighting usage. Cost was a major issue, the first LEDs cost over $200 per diode to produce. Another limiting factor was color, until the 70’s the only color that could be produced by an LED was red. Still another factor was light output, which for a number of years limited the practical usage of LEDs to visual signal applications like indicator lights and signs.
Speaking plainly: It was ideal light to see but not to see by, and it was expensive.
The usage of light-emitting-diodes in light bulbs is a fairly recent and ongoing development. The first mass-installations of LED lighting have happened in just the last few years, and the technology is continuously being improved.
How do they work?
For the purposes of practical lighting usage, the light produced must be roughly white. Since unadulterated LEDs have historically only produced non-white colors, one of two methods is used to create white light.
The first is an RGB system, which works by mixing light output from red, blue, and green diodes in close proximity in order to create white light. The second is using phosphor-based LEDs, which involves coating an LED with phosphor in order to shift the color into the white spectrum. This is similar to the technology used to create different hues of light from fluorescent lamps.
Where are they used?
As is common with rapidly-developing technologies, the ideal applications for LED lighting are changing constantly. Currently, LED lamps are best suited for signs and indicators, night lights, flashlights, undercabinet fixtures, and some recessed light/downlight applications where the constancy of color temperature is not critical. See our LED resources below for more information about whether this technology is suitable for your needs at this time.
Other Helpful Resources