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Saturday, August 13, 2011

LED & Lighting Definitions

CRI: (Color Rendition Index) This rates how well colors are registered under lighting from 0-100 (70-100 most common). Blue colors look blue, reds are red, etc. Halogen and Incandescent lighting is usually thought of as having 100 CRI or close to it which means all your colors will look as they should although I question the CRI of your standard incandescent.
Lumens: A measurement of light perceived by the human eye. You will most often see this measurement on a light bulb packaging. For reference a 60W light bulb usually claims on avg to produce around 600 lumens of omni directional light
Lux: Another measurement of light in a given area using a lux light meter. The higher the lux measurement, the brighter the light. Most homes measure around 400-1000 Lux of visible light on any given day. For comparison, on a bright sunny day you are exposed to 80,000 Lux or more of light.

CCT: (Correlated Color Temperature) This is a measurement of the color of light. For LED lighting this range is usually in the 2500-6500 range. 2700K is called warm white and your traditional incandescent light is in this range. Lights in the 6500 range are very blue looking and are called cool light. The sun shows this quite well. Morning light is more blue (cool) while afternoon and evening light is more amber or (warm)
Omnidirectional: Light being thrown in every direction and angle which is what most incandescent and certain halogen bulbs are
A19: Your classic medium base light bulb
A15: Your smaller medium base bulb often called an appliance bulb
Candelabra: Your common chandelier, coach light, and ceiling fan bulb
Driver: A power supply that provides a constant voltage and current to LEDs and is required for most LEDs to operate. Some drivers are very small while higher wattage drivers can be large.
Phospor: A layer of a certain chemical mixture that is often used to turn blue LED light into white light
Color Mixing: A form of creating white light. Different colors of LEDs mix together to create white light (usually red & amber LEDs)

Remote Phosphor Technology: Another method of turning blue light into white light. A disk or cap is used away from the LED array. When the blue light passes through the phosphors, the light is changed to white
Beam Spread: Some bulbs will give their beam spread in degrees. A narrow spot of light for example would be a 25˚ beam spread, while a wide area of light would be 90˚ or larger.
Binning: When LEDs are manufactured in large quantities there are sometimes slight variations in color and brightness. Manufacturers try and group the LEDs together as closely as they can according to color and brightness. This is important only because some inexpensive bulbs may have low binning standards which means you may have 2 lights from the same manufacturer but they both put off a different color and brightness.

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