Glossary of LED Terms

LED Glossary of Terms

Confused with all the technical terms ? Please see below for a Glossary of LED / Lighting Terms.

Ampere (Amp) the basic unit of electric current reflecting the rate of its flow. Current (Amps) = Power (Watts) / Voltage (Volts)

Candela, or cd A candela is a measurement of the intensity of light and is used in the International Standard (SI) measurement system. Historically, a candela has been roughly equal to the intensity of the light emitted by a regular candle.

Color temperature - Colour temperature measures the colour of a light bulb and not the brightness. This is also used to indicate the 'coolness' and 'warmness' of a LED light source. Colour temperature is measured in degrees Kelvin and is a measure of the part of the colour spectrum that is found in light. A simple way to think about this is to compare the light from the sun from sunrise to sunset. At noon the light is bright and white, even more so nearer the equator. At sunrise and sunset the light takes on a more yellow or even red tint. Lower colour temperatures will have more yellow, and higher colour temperatures will go from yellow, to pure white and eventually to bluish, like you might find on some of the blue tinted headlights on cars. LED Lighting can produce a wide spectrum of Light, unlike their incandescent and halogen predecessors. However, the two main types of colours are Warm white (2750-3250k) and Cool white (6000k). Warm white resembles incandescent and halogen bulbs the closest.

Cool White Is the colour described where the colour temperature is 5000k - 6000k. It is a bright white light that gives off a clinical feel suitable for areas such as offices and hospitals.

Color Rendering Index or CRI the term used to describe the rendered color characteristic of an object. Generally the color looks more natural if CRI is high. Color Rendering Index is based on a scale from 0 to 100 (one hundred being used to characterize natural outdoor light). Cool white CRI is 62, and there are a number of other lighting sources with a variety of rates.

Controller - A device that controls the output of color-changing and tunable white lighting fixtures. Controllers typically have software components for configuring fixtures and designing and editing light shows, and hardware components for sending control data to fixtures.

Driver or ballast An LED driver is a self-contained power supply that has outputs matched to the electrical characteristics of your LED or array of LEDs.

DMX - A digital communications protocol for controlling lighting fixtures, originally developed to control stage lighting.

Luminous Efficacy (or just efficacy) the quotient of the luminous flux emitted by a source of radiation and the power it consumes, measured in lumens per watt (lm/W).

Lumen Output - The total lumens emitted of a light source, system, or solution.

Epoxy tough resistant thermosetting synthetic resin often used to prevent optical decay in a dome or lens, but resulting in insufficient lumen maintenance over time. In the power light sources of Luxeon no epoxy is used, which provides for excellent lumen maintenance.

Flux The total of all the lumens emit by a source.

IP Rating - Ingress Protection Rating classifies and rates the degree of protection provided against the intrusion of solid objects (including body parts like hands and fingers), dust, accidental contact, and water.

Kelvin Temperature (measured in K) describes the comparative color appearance of a certain light source as compared with a theoretical blackbody. For instance, incandescent lamps of yellowish color are characterized by the value of 3000, while the range of values for fluorescent light sources can be from 3000K to more than 7500K.

LED Light Emitting Diode (LED) is a diode of semiconductor material, such as gallium arsenide, that emits light when a forward bias (a voltage used in the direction that produces the larger current) is applied, the color depending on the semiconductor material. Each semiconductor comprises two regions of the opposite electrical charges. The electrons start moving as soon as voltage is applied, so certain amounts of energy are released as a result. As the energy disperses the wavelengths become visible and we may observe the light of a certain color.

Lumen (lm) A lumen is a measurement of light directly relevant to human beings. The lumen scale describes the amount of light, or brightness, that the human eye perceives. All lightbulb packaging now shows the number of lumens the bulb produces. For example, a 6w LED GU10 produces approximately 330lms.

lumen maintenance the percentage of the remaining flux at the rated life of a source of light.

Lux (lx) the derived SI unit of illumination equal to a luminous flux of 1 lumen per square meter.

RGB color model is an additive colour model in which red, green and blue light are added together in various ways to reproduce a broad array of colours. The name of the model comes from the initials of the three additive primary colours red, green and blue.

SMD - surface mounted LEDs

Solid-state lighting used to describe light sources that are not likely to rupture, leak, shatter or break, contaminating the environment.

Thermal management the process of adjusting the operating temperature of a certain device through its design, e.g. by applying heat sinks and improving airflow.

Volt the derived SI unit of electric potential; describes the difference between two points on a conductor carrying a current of 1 ampere, when the power dissipated between these points is 1 watt (e.g. 1.5V).

Warm White describes light with certain temperature correlated to it (usually between 3000K and 3500K); the colour of light appears somewhat yellow.

Watt A watt is a measurement of electrical power, formally equal to the amount of energy in 1 ampere of current flowing at 1 volt. A lightbulb that is rated at, say, 200 watts uses more electricity to produce light than a bulb rated for 100 watts. This rating may be found in the instruction for every lamp or other kinds of light sources. The higher the value is indicated the more efficient the lamp is.