Standard Deviation Colour Matching (SDCM)
A
Describes the difference between two colours. A difference between one to three “steps,” SDCM is almost imperceptible, a difference of four steps, SDCM is barely visible and a difference of more than four steps, SDCM is visible.
Normal phosphor coverage
The process of applying the converting phosphor in even layers, so that to cover the LED chip, usually blue.
Warm white
A description of the light correlated with the colour temperature between 3000K and 3500K, usually perceived as slightly yellowish.
Cold white
A description of a colour temperature range exceeding 6000K, perceived as slightly bluish.
RGB white
A method of generating the white light by combining the light emitted by the red, green and blue LEDs.
AlGaAs
One of the combinations of materials used for manufacturing the LEDs generating the light in the red and amber area of the visible spectrum.
AllnGaP
The technology for the production of LED chips (Light Emitting Diode), which uses junctions with aluminium, indium, gallium and phosphor to produce the red, orange and amber LEDs.
American National Standards Institute (ANSI)
A non-profit organization which develops standards by voluntary consensus and conformity assessment systems for products, services, processes, systems and personnel, in the United States of America.
Ampere (A)
The unit for measuring the intensity of the electric current: the current intensity (Ampere) = Power (W) / Voltage (Volt)
ANSI Binning
The system defined by the American National Standards Institute for grouping the features of the light emitting diodes, such as colour temperature, light flow, etc.
B
Ballast
Device used for ensuring the lighting and light maintaining of a lamp, limiting and regulating the current during functioning (it ensures the voltage, the wave form necessary for turning on the lamp). It usually is a ferromagnetic core over which it is coiled a Cu winding, named electromagnetic ballast. These were replaced with electronic ballasts.
Bin (Binning)
The systematic division of the performance parameters distribution (Flow, Wave length or CCT and Vf.), in small, finite groups which can be selected to optimize the assembly performance.
C
Candela
The unit of luminous intensity, describing the intensity of a light source on a certain direction.
CCT – Correlated Colour Temperature: See Colour Temperature
Chip – see LED chip
CIE – see the International Commission of Illumination
LED chip (Chip)
Light emitting semi-conductive device which can be, or not, incorporated in a LED.
Power factor compensation
In an electric device, such as a LED lighting fitting, a system of inductors, condensers or converters that regulates the power factor of the device and brings it close to the ideal power factor, namely 1.0.
Controller
A device that controls the light emitted by the lighting fittings and which generates the change in either light colour or intensity or both. The controllers usually have components that can be programmed by software for configuration and with which light shows can be performed and projected. They also include hardware components for sending the control data to the lighting fitting.
Conversion by Phosphor
This is the process by which the photons in a Led chip are converted to a different colour by absorption and subsequently by phosphorescence. The white LEDs as well as some coloured LEDs are made using the phosphor conversion, so that, to the basic colour, the one emitted by phosphor is added. As a result, the two colours can be perceived by the human eye as white or another colour.
Lighting fitting or device
A full lighting assembly including one or several lamps, a supply source, an optical system as well as other accessories.
Black body/ black body radiation
An object absorbing all electro-magnetic radiations that fall on it. As it does not reflect the light, a black body appears as it were black. A black body heated to incandescence, radiates the light in a sequence of colours, from red to orange, to yellow, to white, to blue, depending on its temperature. This sequence of colours describes a curve in a colour area, it is known as the black body curve.
Traditional lighting fittings or devices
Devices including as light emitting source traditional lamps such as the incandescent or fluorescent ones.
LED lighting fitting or device
A complete lighting unit made of LED light emitting elements, a proper driver, as well as components intended to spread the light, to position and protect the light emitting elements and to connect the device to a current circuit. The LED light emitting elements can be singular or multiple, type engine, LED matrixes (modules) or LED lamps. The LED lighting device is intended to connect directly to a power supply circuit.
Owning cost
The overall cost of the owner of the lighting device(s) includes the purchase cost and the maintenance and functioning one.
CRI – Colour Rendering Index: See Colour Rendering Index
Chromaticity
An objective specification of a colour quality, independent of its luminance, characterised by saturation and colour.
The black body curve
A curve in a colour area that describes the colour sequence emitted by a black body radiator- at various temperatures.
The light flow maintenance curve
A chart illustrating the (anticipated) behaviour of the emission of light depending on time, for a light emitting source, usually with LED.
D
DALI – see Digital Addressable Lighting Interface
Colour definition
The colour of the even lighted objects, described by three terms:
Halo: It describes the situation in which the aspect of various colours is similar (for example blue is paired with pink).
Brightness: It describes a series of shades between white and black.
Chromatics: It describes the farness degree in relation to grey of the same brightness and the colour increase degree (for example red, redder, pure red).
Light flow depreciation
It describes the light flow percentage lost during a time period, in relation to the initial one. See the light flow maintenance for more information.
CIE chromatic chart
Horseshoe- shaped and it illustrates the chromatic distribution in the colour spectrum. See high definition colours, Chromatics.
Light diffuser
An optical material with unevenness on the surface that leads to redirecting and spreading the light beans.
ELV dimmer
An electronic device, used to adjust the light intensity emitted by the LED lighting fittings.
Dimmer Leading Edge
A type of dimmer which adjusts the power of lamps by delaying the increasing edge of the first half of the alternative current harmonic curve. Compatible with certain LED lighting fittings.
Dimmer Trailing Edge
A type of dimmer which adjusts the power of lamps by delaying the decreasing edge of the first half of the alternative current harmonic curve. Compatible with many LED lighting fittings.
Light Emitting Diode – LED
A light emitting diode (LED) is a solid-state device made of semi-conductive material which converts electric energy into light. It does not require heating to emit the light and thus it does not have filament. The simplest structure is made of two regions of semi-conductive materials. The p region includes positive electric loads, while the n region includes negative electric loads. When voltage is applied, the electrons move from region n into region p. The movement process of an electron, by pn junction, releases energy. The dispersion of this energy generates photons with wave length in the visible spectrum.
DMX
A digital communication protocol for controlling the lighting fittings, initially developed for controlling the lighting on stage.
Driver for LED
An electronic circuit which converts the input voltage into a power source or constant voltage, despite the input voltage fluctuations. A driver protects the LED against normal voltage fluctuations, overvoltage and voltage peaks.
Driver
Electronic device used for the supply of the lighting devices, usually with LED.
E
Light effectiveness
The light emitted by a light source, divided by the electric power consumed by that source, expressed in lumen per watt (lm / W). Used in case of application.
Light efficiency see Light effectiveness
Used in case of light source.
The efficiency of the lighting fitting or device
It usually refers to the efficiency of converting the electric energy into light. This is defined as the radiant flow related to the absorbed electric energy.
MacAadam Ellipse
A MacAadam Ellipse is the region in the chromaticity chart that includes all the colours which are differentiable for the average human eye, related to the centre of the ellipse.
F
Cold/warm performance factor
The relative level of light performance at a temperature related to the light obtained at a nominal or testing temperature.
Power factor
The active power related to the apparent power (for example, the product between the input voltage rms and the input current of a driver).
Flow/ Light flow
The Light flow is the measure of the light power, adjusted to reflect the different sensitivities of the human eye to the various wave length of the light.
Emitted light flow
The overall quantity of lumens emitted by a light source, a system, or a solution.
Light flow – See Flow
Lighting flow – See Light flow
Radiant flow
The overall quantity of light energy measured in watts, emitted by a light source in all wave length.
Phosphor
A layer of phosphorescent material which, if blue photons, for example regal, pass through it, emits photons in another part of the visible area.
Phosphor used remotely
A converting technique based on phosphor, where, the photons from the blue LEDs pass through a material with and which is not attached to the LEDs chips.
Photocell
A photosensitive device used to detect the light level and implicit, it can control the lighting fittings or certain dimmers as answer to the detected light level.
FR4
A material of which the printed circuit board used on a large scale is made, of laminated epoxi resins, strengthened with glass fibre and which represents the insulating base for the conductive layouts made of Cu.
G
Colour range
The colour range included in the CIE chromatic chart derived from the combination of various sources.
Goniophotometer
A photometric device used for testing the light intensity distribution, and the light flow of the lighting fittings.
H
I
IES / IESNA -see Illuminating Engineering Society (IES).
Illuminance
The intensity of light falling on a surface area. The measuring unit for illuminance is lux (lx).
Infrared
Electromagnetic radiations with wavelength range from 700 nm – 3000 nm.
Colour Rendering Index (CRI)
A measure of the degree of colour rendering to objects when lighted by a light source as compared with the same objects when lighted by a reference source of comparable colour temperature. The reference source has a CRI of 100.
Integration of the power source on the circuit board
An approach of the power management that integrates the power supply into a device casing, removing the necessity for an external power supply.
Digital Addressable Lighting Interface (DALI)
A digital communication protocol for controlling and adjusting the lighting fittings, initially developed in Europe.
J
PN junction
Semi- conductive structure consisting of a positively loaded region and a negatively loaded region. When a current is applied, the electrons move from region n into region p. The movement process of an electron, by pn junction, releases energy. The dispersion of this energy generates photons with visible wave length in case of a LED.
K
Kelvin (K)/ Colour temperature, Kelvin
It is a measure of the colour of a light source in relation to the one of a black body heated at a certain temperature expressed in Kelvin (K). The incandescent lamps have a low colour temperature (around 2800K) and yellow- reddish tones; the daylight has a high colour temperature (around 6000K) and seems bluish. The lamps with the colour temperature below 5000K are more yellowish/reddish, the ones between 5000K and 6000K appear as white, and those over 6000K bluish.
L
Compact fluorescent lamp (CFL)
Small size fluorescent lamps used as alternatives to the incandescent lamps.
Fluorescent lamp
Light source consisting of a tube filled with Argon, Krypton or other inert gas. When the electric current passes, the resulted electric arc emits ultraviolet radiation which incites the phosphor on the inner walls of the lamp, making them emitting a visible light.
High Intensity Discharge Lamp (HID)
Generic term describing lighting sources with Mercury vapours, metallic halogens, high pressure Sodium.
LED – see Light Emitting Diode
High power LED
A high power LED, sometimes called power LED, is a LED that uses a high supply current, for example 350 mA or higher.
LED Engine
An integrated assembly made of LEDs or LED matrixes and other optic, thermic, mechanic and electric components.
InGaN
The semi-conductive material for LED (Light Emitting Diode), which includes indium, gallium and nitrogen to generate green, blue and white light.
Organic LED (OLED)
The Organic LED (OLED) is based on an organic material (carbon- based). As opposed to LEDs, which are point-like sources, the OLEDs are made in foils which offer a diffuse light source. The OLED technology is developing fast and it is more and more used in displaying applications, such as mobile phones and PDA screens. However, the OLEDs are still a few years far from becoming a practical source for general lighting. Additional progress is required concerning light production, colour, efficiency, costs and lifecycle
Without binning classification
It describes the case in which the entire production of white LEDs can be described by a single CCT and by a number stated on the MacAdam ellipse. It is not required subdividing or colour binning dividing regarding LEDs, in order to use them in the intended application.
The place of the Planckian black body
The line on the CIE chromaticity chart describing the colour temperature of an object heated from approximately 1.000 K to over 10.000 K.
Lumen (lm)
The international (SI) unit of light flow or quantity of light and equals the amount of light that is spread over a surface by a light source when all parts of the surface are exactly one meter far from the light source. For example, a candle emits about 12 lumens.
Luminance
Photometric term, quantifying the brightness of a light source or of a lighted surface that reflects light. It is expressed in candela/ square meter.
Adjustable white light
LED lighting fittings with white light, which combine the warm white and cold white LEDs to generate a colour temperature range.
Emitted light
The amount of light emitted by a lighting device or a lighting installation in a target activity area or on a target surface, measured in lux (lx).
Lux (lx)
The SI (International System) unit of lighting, which measures the light flow incident on a unit area, frequently defined as one lumen per square meter (lm/m2).
M
Thermic management
The control of the functioning temperature of the product by design, for example the usage of radiators and air circulation.
Composition material
The material, such as Aluminium, AlInGaP and InGaN, used in a LED to generate the light of a certain colour.
Type P material
In a semi-conductive diode with PN junction, the type P material is positively loaded. The atoms in the type P material have electrons holes (the electrons are missing from the external rings).
LED matrixes
A LED assembly on a printed circuit board or sub-layer, eventually optic elements, additional thermic, mechanic, electric interfaces intended to be connected to a LED driver.
LED matrixes
Multiple semi-conductive chips that emit light.
MCPCB
A wide accepted material for printed circuits (PCB), with metal core (MC) for a better thermic performance.
Light flow maintenance
The maintenance of the light flow at a certain moment in the life of the light source. It is expressed as percentage of the original light flow.
Colour pattern
An abstract mathematical pattern which describes the way in which the colours can be represented as value groups or component colours. RGB (red-green-blue) is a colour pattern, with three component colours and CMYK (cyan-magenta-yellow and key (Black)) is a colour pattern with four component colours.
RGB colour pattern
An additional colour pattern in which red, green and blue are added together in various proportions to generate a wide range of colours, including white.
Additional colour pattern
A type of RGB colour pattern which describes the way in which various proportions of red, green and blue combine to generate colours. In the additional colour pattern, combining red, green and blue generates white light.
Subtractive colour pattern
A colour pattern that applies to the reflective surfaces, such as paint, pigment and ink. Combining red, green and blue in equal quantities generates black.
Pulse width modulation (PWM)
A method, used for the LEDs driver, to adjust the current or the LEDs supply voltage.
N
High level of brightness
High level of brightness is a term which is often applied to LEDs, but it lacks a measured significance and it does not indicate a performance level.
Nit
Measuring unit for the brightness of the display screen. 1 nit = 1 cd/m2.
O
P
Amber PC (converted by phosphor)
Amber PC is a method of making the LEDs amber coloured, using LED chips
That emit blue light This requires the usage of special phosphor and are less sensitive to temperatures and the amber LEDs are more coherent.
Lifecycle
The quantity of light emitted by a lighting fitting in an application, after a period of time during which it diminished in a percentage related to the initial value.
The white point
The coordinate colour temperature (CCT), defined by a perpendicular line on the Planckian black body curve and which crosses the measured chromatics.
Printed circuit PCB
Material used on a large scale for printed circuit boards (PCB), material made of laminated epoxi resins, strengthened with glass fibre, which are fire resistant.
R
Radiator
A part of the thermic system which leads ore removes by convection the heat from the generating components, such as LEDs and electronic components.
Radiometry
The measuring of radiant energy (including light), in terms of absolute power.
Epoxi resins
Organic polymer frequently used for encapsulation or lenses, predisposed to optic wear in time, leading to the poor maintenance of the light flow. The high quality LEDs do not include any epoxi resins in the optic system and what contributes to the upper maintenance of the light flow.
Colour rendering
A general expression for the effect of a light source on the aspect of the objects colour.
Retrofit
It refers to the replacement of the light source without replacing the cap. They are less energetic efficient than the specially designed LED lighting fittings, but they have the advantage of being easily used inside the traditional lighting fittings.
Remanence (Ghosting)
The effect that appears when the turned off lighting fittings glow weakly, as a result of the residual voltage inside the circuit.
Thermic resistance (K / W)
The property of a material capacity to conduct heat.
S
SDCM – see Standard Deviation Colour Matching
Integration sphere (Integrator)
A device used for a variety of optic, photometric or radiometric measurements.
SMDs
Surface Mounted Devices: resistances, condensers, transistors, LEDs, installed on the surface (usually printed circuit).
Cap
Part of the lamp used to fix it so that it is power supplied. There are several types and sizes. The most used in Europe are E26/27, where 26 or 27 is the diameter, measured in millimetres, of the part which is threaded in the clamp.
Illuminating Engineering Society (IES) of North America
Authority recognised from the technical point of view regarding lighting, information communication concerning all the aspects related to good practices in the lighting field, other publications and services.
(Lighting) Solid-state
A description of the devices that do not contain moving parts or parts that can break, crack, generate leakages or contaminate the environment. The solid state sources use the LEDs property to emit light.
(Function) light efficiency spectrum
A bell-shaped curve that describes a sensitivity of the human eye, with normal sight of the visible spectrum. It is also known as the eye sensitivity curve V(λ).
CIE 1931 colour area
A standard colour area created by the International Commission of Illumination (CIE), in 1931, to define the entire visible colour range for average people.
NTSC colour area
The colour range included in the CIE chromaticity chart when phosphor-based RGB sources are combined in a CRT tube for a television or computer monitor.
Colour spectrum/ visible spectrum
The visible spectrum is part of the electromagnetic spectrum which is visible to human eye.
Steradian
The standard measuring unit for the solid angle. It describes the bi-dimensional angle extended in tri-dimensional area.
Glow
It is usually improper used in relation to lighting, as synonym for light flow, an objective measure of the visible power emitted by a light source. The term is used correctly when it describes the brightness of a display or TV screen.
Directional light source
A light source that emits light only in the direction to which it is directed or pointed.
T
Ta – See Ambient Temperature
Tc – See Casing Temperature
Casing Temperature
The temperature measured on the level of the LED coating or structure.
Colour temperature
The term used for describing the effect of an object heated until it becomes incandescent, the emitted radiations and the apparent colour, changing proportionally with the temperature; easy to understand if it is considered the hot metal in a forge, which becomes red, then orange and white as the temperature increases.
The correlated colour temperature (CCT),
The absolute temperature of a black body whose chromatics looks better like the one of the light source. It is usually specified in Kelvin (K). The lower the Kelvin temperature is, the warmer the light feels or seems.
The junction temperature
The junction temperature, marked as Tj is the temperature in the active region of the LED.
Kelvin temperature
Term and symbol (K), used to indicate the colour aspect of a light source by comparison to a theoretic black body. The yellowish incandescent lamps have 3000K. The fluorescent light sources vary from 3000K to 7500K and even more.
The environmental temperature (Ta)
The temperature of the air around the device.
Warm testing
The performance tests and the LED specifications at a temperature of 85 °C or stated by the producer.
The radiator temperature
The measured temperature of the radiator during testing. This contributes to the leading and dissipation of the heat of the heat generating component in the LED instance.
Tj – see Junction Temperature
Tp – See Thermic disperser temperature
U
Ultraviolet (UV)
Electromagnetic radiation with a wave length shorter than the one of the visible light.
V
Volt
The measuring unit for the potential difference between two electric loaded conductors.
W
Watt
The measuring unit for the electric power used by a device during functioning. Most lamps have the consumed power stated in Watt.
