Leading Edge Dimmer A type of dimmer that regulates power to lamps by delaying the leading edge of each half-cycle of AC power. Compatible with many LED fixtures.
LED See Light-Emitting Diode.
LED Array An assembly of LED packages or dies on a printed circuit board or substrate, possibly with optical elements and additional thermal, mechanical, and electrical interfaces that are intended to connect to the load side of an LED driver.
LED Chip (Chip) The light-producing semiconductor device that may or may not be incorporated into an LED.
LED Driver An electronic circuit that converts input power into a current source - a source in which current remains constant despite fluctuations in voltage. An LED driver protects LEDs from normal voltage fluctuations, overvoltages, and voltage spikes.
LED Light Engine An integrated assembly comprised of LEDs or LED arrays; an LED driver; and other optical, thermal, mechanical, and electrical components.
LED Luminaire A complete lighting unit consisting of LED-based, light-emitting elements and a matched driver. An LED luminaire distributes light; positions and protects the light-emitting elements; and connects the unit to a branch circuit. The elements may take the form of LED packages (components), LED arrays (modules), LED Light Engine, or LED lamps. The LED luminaire is intended to connect directly to a branch circuit.
LED Module See LED Array.
Light-Emitting Diode (LED) A solid-state, semiconductor device that converts electrical energy directly into light. On its most basic level, the semiconductor is comprised of two regions. The p-region contains positive electrical charges, while the n-region contains negative electrical charges. When voltage is applied and current begins to flow, the electrons move across the n-region into the p region. The process of an electron moving through the p-n junction releases energy. The dispersion of this energy produces photons with visible wavelengths.
Light Output See Flux/Luminous Flux.
Lumen (lm) The international (SI) unit of luminous flux, or quantity of light; equals the amount of light that is spread over a square foot of surface by one candle power when all parts of the surface are exactly one foot from the light source. For example, a dinner candle provides about 12 lumens.
Lumen Depreciation The percentage of light lost relative to the initial lumen output. See Lumen Maintenance for more information.
Lumen Maintenance The luminous flux at a give time in the life of the LED; expressed as a percentage of the initial luminous flux.
Lumen Maintenance Curve A graph illustrating the predicted average light output behavior over time of a single LED or solution.
Lumen Output The total lumens emitted from a light source, system, or solution.
Luminaire A lighting fixture complete with installed lamps and other accessories.
Luminous Efficiency The percentage of total lamp lumens that a lighting fixture, luminaire, or system emits, minus any blocked or wasted light.
Luminous Flux See Flux/Luminous Flux.
Lumiramic This Philips proprietary phosphor system embeds phosphor in a ceramic platelet that can be mass manufactured with high uniformity and consistency.
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).