Glossary
ANSI - binning is a selection method according to standard set by American National Standard Institute of LEDs. It is used by LED manufacturers to manage the variation of LED performance in mass production processes.
Bin - selected group of performance parameters (Flux, Color or CCT, and Vf) that meets aesthetic requirements of the assembly. Although the word "bin" is the preferred term, sometimes one will find the word "rank" in use.
Binning - process of selecting parameters into groups according to chosen schematics for example – according to Mc Adams selection method (color, flux, forward voltage) products which are grouped in the same bin are characterized by very similar parameters so from practical point of view (luminaries production) might be treated as „identical”
Candela (cd) - the luminous intensity as defined by the international metric standard (SI). The term, retained from the early days of lighting, defines a standard candle of a fixed size and composition as a basis for evaluating the intensity of other light sources.
Chromaticity - is an objective specification of the quality of a color regardless of its luminance.
CIE Chromaticity Diagram - line connecting the chromaticities of the spectrum of colors.
Color Definition - the color of uniformly illuminated objects described using three terms:
- Hue: Describes the situation when the appearance of different colors is similar
- Lightness: Describes a range of grayness between black and white.
- Chroma: Describes the degree of departure from gray of the same lightness and increasing color (e.g. red, redder, pure red).
Color spectrum - all wavelengths perceived by human sight, usually measured in nanometers (nm).
Color temperature - the description of the effect of heating an object until it glows incandescently; the emitted radiation, and apparent color, changes proportionally to the temperature; easily envisioned when considering hot metal in a forge that glows red, then orange, and then white as the temperature increases.
Cool White - a description of light with a correlated color temperature between 5000K and 7500K, usually perceived a slightly blue.
Correlated Color Temperature (CCT) - the phrase use to describe the temperature at which a Planckian Black Body Radiator and an illumination source's appear to match, usually specified in Kelvin (K).
CRI or Color Rendering Index - the calculated rendered color of an object. The higher the CRI (based upon a 0-100 scale), the more natural the colors appear. Natural outdoor light has a CRI of 100 which is maximum value. Lower CRI values indicate that some colors may appear unnatural when illuminated by the lamp. Usually most affected color is red. Common lighting sources have a large range of CRI.
For example: incandescent bulb has a CRI of 100
Cool white fluorescent lamp has a CRI of 62
Contrast - is the relationship between the luminance of an object and background on which light source is presented.
Die (chip, crystal) - core of the LED used by LED manufacturers for their production. There are a few real LED chips manufactures, the rest must buy chips for their production. Size of crystal and quality, strongly influence the final price of LED.
Diffuser - an optical element used to mix light rays to improve uniformity ( to avoid light points, full surface is illuminating)
Driver - electronics used to power illumination sources.
Efficacy - (Luminous Efficacy) - is a measure how good light source utilize supplied energy to produce visible light. The light output of a light source divided by the total electrical power input to that source, expressed in lumens per watt (lm/W). Ideal monochromatic (green light) at 555 nm source 683 lm/W is 100% (maximum possible luminous efficacy)
Flux - the sum of all the lumens (lm) emitted by a source
InGaN LED - the preferred LED (Light Emitting Diode) semiconductor technology containing Indium, Gallium, and Nitrogen to produce green, blue and white-colored LED light sources.
Kelvin Temperature - term and symbol (K) used to indicate the comparative color appearance of a light source when compared to a theoretical blackbody. Yellowish incandescent lamps are 3000K. Fluorescent light sources range from 3000K to 7500K and higher.
LED - what is this and who invented it? There are no clear answer to be fair:
In 1927, Russian researcher Oleg Vladimirovich Losev published information about luminous semiconductor materials - crystals, however no practical LED products were created at that time.
In 1962, engineer Nick Holonyack, working as consultant for General Electric , invented the first visible light LED.
In 1994, Shuji Nakamura invented the first blue LED, which has enabled future production of bright and energy-saving white light source.
LED stands for - Light Emitting Diode it is a solid-state semiconductor device that converts electrical energy directly into light. By applying voltage, current begins to flow via semiconductor built from two regions (p and n). Electrons move across the n region into the p region. While electrons are moving through the p-n junction, energy is released. The dispersion of this energy produces photons with visible wavelengths of different colours.
LED can have different meaning in practice:
LED chip or die - not useful for end user at all
LED as a component - limited usage for end customer
LED module , may include optics, heat sink, power supply or driver - from this product level usually end customer starts
LED luminaire - complete set for the end user
Lumen (lm) - quantity of light according to international standard (SI). If a light source emits one candela of luminous intensity uniformly across a solid angle of one steradian, the total luminous flux emitted into that angle is one lumen (1 cd·1 sr = 1 lm). Alternatively, an isotropic one-candela light-source emits a total luminous flux of exactly 4π lumens. For example, a dinner candle provides about 12 lumens. A 60-Watt Soft White incandescent lamp provides 840 lumens. (definition by Wikipedia en.wikipedia.org)
Lumen Maintenance Curve - a graph comparing the loss of light output against the time the light source is used.
Luminaire - a complete lighting fixture with installed lamps and other accessories.
Luminaire efficacy- measures the efficacy of the complete luminaire, or fixture, taking into account the optics, thermal design, and other design factors that impact efficacy. It is calculated by measuring the total light output of a luminaire, divided by the amount of power drawn by that luminaire. It is expressed in lumens per watt (lm/W).
Lux (lx) - the SI (International) unit of illuminance, or luminous flux incident on a unit area, frequently defined as one lumen per square meter (lm/m2).
Nits - measurement of display screen brightness. 1 nit = 1 cd/m2. The more nits, the brighter the picture.
Optic - a device that changes the direction of a ray of visible light, usually by reflection, such as a mirror, or refraction by lens.
Source efficacy - measures the efficacy of the light source, separate from the fixture. It is calculated by measuring the total light output of a lamp/power supply system, divided by the power drawn by that system. (It does not account for losses caused when that system is installed in a fixture.) It is expressed in lumens per watt (lm/W).
Thermal management - controlling the operating temperature of the product through design; examples includes heat sinks and improved airflow.
Thermal resistance (C/W) – rise in temperature of LED per unit of power dissipated. Lower resistance is preferred.
Warm White - a description of light with a correlated color temperature between 3000K and 3500K, usually perceived a slightly yellow.
Super Warm White - A description of light with a correlated color temperature 2700K; this is closest to the saloon incandescent lamps.
Watt - the unit of electrical power as used by an electrical device during its operation. Many lamps come with rating in watts to indicate their power consumption. A light source with a higher lumen per watt value is more efficient.
White point - is a set of chromaticity coordinates that define the color "white"
