LED technology glossary 43 terms
The key terms of the LED display world, clearly defined. Each term has its own page with definition, formula and related concepts.
C
- Calibration Equalising the brightness and colour of all pixels and modules into a uniform image.
- Candelacd SI base unit of luminous intensity: the luminous flux a source emits in one direction.
- CIE The international standardisation body for light, colour and lighting.
- CMS Another name for an electronic sign with changing messages (see VMS).
- COB LED Bare chips directly on the board, covered with resin; for the finest pixel pitch.
- Colour depth The number of grayscale levels per colour, expressed in bits (14-bit = 16,384, 16-bit = 65,536).
- Colour temperatureK The ‘warmth’ or ‘coolness’ of white light, expressed in kelvin (e.g. 6500 K).
- Cone of vision The sharp zone in front of the eyes where vision is most acute (in traffic terms ~10–35°).
- Cones and rods The two kinds of light cell in the retina: cones for colour and daylight, rods for low light.
- Conspicuity A sign’s ability to attract attention and stand out against its surroundings.
- Contrast ratio The ratio between the brightest and darkest output of a screen.
D
F
- Flip-chip LED chip mounted upside down, without bond wires; for fine pitch and better heat dissipation.
- Fovea Small central area of the retina, packed with cones; provides the sharpest vision.
- Frame rate The number of images per second in the content; to be distinguished from the refresh rate.
- Frequencyν The number of waves passing a point per second; inversely proportional to wavelength.
G
I
L
- Legibility The ease with which the content of a sign can be read.
- Legibility IndexLI The legible distance per unit of character height (feet per inch); LI = 30 is the current recommendation.
- Lumenlm The total amount of visible light a source emits in all directions.
- Luminancecd/m² How bright a surface appears; the photometric quantity closest to ‘brightness’.
- Luminance contrast The luminance difference that determines a screen’s legibility and conspicuity.
- Luxlx Amount of light arriving on a surface (lumen per m²).
M
P
R
- Radiometry Measuring light in pure physical energy (watts), independent of the human eye.
- Reflection The ratio of reflected luminance to incident illuminance, as a percentage.
- Refresh rateHz The number of times per second a screen rebuilds its image (e.g. 1920 or 3840 Hz).
- Retroreflection Reflection of light back towards the source, as on road signs and hi-vis material.
S
V
No term found.