In the world of LEDs, as with any new technology, there are a lot of new terms which need to be mastered in order to properly understand the features and elements of the system. Rather than focusing on the specific terms for Inspired LED products, as we have done in previous blogs, this week’s lesson will focus on more general industry terms. The more you understand about these common LED words, the better equipped you will be to have discussions and make decisions regarding LED technology.
Lumen: [\ˈlü-mən\]
Noun, Plural- Lumens, Abbreviation- lm
- The unit of luminous flux, equal to the luminous flux emitted in a unit solid angle by a point source of one candle intensity
In laymen’s terms, lumens are a unit of measurement solely used to describe the overall brightness, or total quantity of visible light emitted from a particular light source. A single lumen is said to be equal to the light output of a single candle. One foot of Inspired LED Normal Bright flex produces around 100 lumens; that’s the equivalent of 100 candles! At Inspired LED, we offer a variety of brightness levels for our products, ranging from Normal Bright, to Super, Ultra, and Mega, all the way up to Double Ultra Bright, each producing a greater lumen output than the last.
Kelvin Color Temperature: [\ˈkel-vən\ \ˈkə-lər\ \ˈtem-pə(r)-ˌchu̇r\]
Noun, Plural- Kelvin Color Temperatures, Abbreviation- K
- A method of describing the characteristic of visible light as emitted by an ideal black-body radiator over a range of temperatures
To put it simply, Kelvin color temperature describes the range of colors which can be emitted by a true-black object as it experiences an increase in temperature. It is easiest to visualize in terms of a piece of metal, such as a lamp filament, or even a brick of charcoal. As heat is applied, the black object will begin to glow red, then orange, yellow, and bright white. If heat is continually applied the white will eventually fade into a bright blue. The term “Kelvins” refers to the measurable temperature at which each color is experienced in this example.
As you can see from the image above, the Kelvin Color Temperature scale describes only a range of red to blue light. Since a heated object will not naturally turn to shades of green or purple, these colors cannot be described on the Kelvin scale. This scale is, however, an ideal way to measure and describe varying shades of white light, like those offered at Inspired LED. Our LEDs are currently available in 3000K, 4200K, and 6000K, depending on the product.
Correlated Color Temperature: [\ˈkȯr-ə-lət-əd\ \ˈkə-lər\ \ˈtem-pə(r)-ˌchu̇r\]
Noun, Plural- Correlated Color Temperatures, Abbreviation- CCT
- A measure of a light source’s color appearance as defined by the proximity of the light source’s chromaticity coordinates
Without getting into all the technical details of isotemperatures and the CIE 1976 chromaticity diagram, correlated color temperature can be described as a method used by the lighting industry to help describe the general color appearance of different white lights in simple terms. While Kelvin Color Temperature (as described above) refers to the specific measurement of a white light, CCT assigns more general terms to the perceived “warmth” or “coolness” of the light’s appearance. Typically, “warm” white is used to describe those lights with low CCT values (measuring 2700K – 3000K), and “cool” white describes those lights with high CCT values (4000K – 6500K). Inspired LED offers both warm white and cool white LED products, as well as our own unique “pure white” option to describe the crisp shade of white between 3000K and 4000K.
Color Rendering Index: [\ˈkə-lər\ \ˈren-dər-iŋ\ \ˈin-ˌdeks\]
Noun, Plural- Color Rendering Indexes, Abbreviation- CRI
- A quantitative measure of the ability of a light source to reveal the colors of various objects faithfully in comparison to a natural light source
Unlike the Kelvin scale or correlated color temperature, the color rendering index is not used to describe the appearance of the light source itself. Rather, it is a way to measure the light’s effect on its surroundings. Depending on the style and quality of a light source, the apparent colors of the environment will shift, and may take on different hues. This is an important consideration for any lighting application, but most especially in the world of photography and film. Those lights which greatly alter the appearance of surrounding colors are said to have a low CRI, while those which preserve the natural color and appearance are described as having a high CRI. The highest possible CRI value is 100, the perfect depiction of an object’s natural color, though depending on the source, some lights may register as low as negative numbers. Most fluorescent bulbs have a CRI rating of around 50, while most LEDs have a rating of 80 or higher.
To learn more about LED lighting, be sure to follow the Inspired LED blog, and look for other installments of Inspired LED 101. If you have specific questions about our products and services, you can visit our website, contact us directly through email at orders@inspiredled.com, or give us a call at 480-941-4286.
Sources Cited:
http://www.merriam-webster.com/dictionary/lumen
http://lowel.tiffen.com/edu/color_temperature_and_rendering_demystified.html
http://www.lrc.rpi.edu/programs/nlpip/lightinganswers/lightsources/whatisCCT.asp#
https://en.wikipedia.org/wiki/Color_rendering_index
http://richbrilliantwilling.com/blogs/light-reading/15947112-energy-efficiency-and-cri
http://climeflashlight.com/lumen-flashlight-how-to-choose-the-right-one/
