This section is a compilation of terms associated with lighting used frequently throughout this website. Getting a good grasp of these terms will help you to attain a good understanding of lighting basics and also in the better application of our products.
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z
-- A --
Directional lighting to emphasize a particular object or draw attention to a display item.
The general lighting present in an area - excluding task lighting and accent lighting but including general lighting and daylight.
-- B --
A device used with an electric-discharge lamp to obtain the necessary circuit conditions (voltage, current and waveform) for starting and operating.
The angle between the two directions for which the intensity is 50% of the maximum intensity as measured in a plane through the nominal beam centerline. For beams that do not possess rotational symmetry, the beam angle is generally given for two planes at 90 degrees, typically the maximum and minimum angles. Note that in certain fields of application, beam angle was formerly measured to 10% of maximum intensity.
-- C --
The Standard International unit of luminous intensity. One candela is one lumen per steradian. Formerly, candle.
The absolute temperature of a blackbody whose chromaticity most nearly resembles that of the light source.
High brightness SMD white LEDs. They consist of multiple chips /dies on one board.
Constant current LED Drivers
Constant current (CC) LED drivers keep a constant electric current throughout an electronic circuit by having a variable voltage. CC drivers are often the most popular choice for LED applications. CC LED drivers can be used for individual bulbs or a chain of LEDs in series
Constant Voltage LED Drivers
Constant voltage (CV) LED drivers are power supplies. They have a set voltage that they supply to the electronic circuit. You would use CV LED drivers to run multiple LEDs in parallel, for example LED strips.
Measure of the degree of color shift objects undergo when illuminated by the light source as compared with the color of those same objects when illuminated by a reference source, of comparable color temperature.
-- D --
A device to redirect or scatter light from a source, primarily by the process of diffuse transmission.
A device used to control the intensity of light emitted by a luminaire by controlling the voltage or current available to it
A device composed of a power source and light emitting diode (LED) control circuitry designed to operate an LED package (component), an LED array (module), or an LED lamp
-- E --
-- G --
The sensation produced by luminances within the visual field that are sufficiently greater than the luminance to which the eyes are adapted, which causes annoyance, discomfort, or loss in visual performance and visibility.
-- H --
Non-linear loads such as inductive or capacitive loads draw current in abrupt pulses rather than in smooth sinusoidal manner create harmonics. These pulses cause distorted wave shapes, due to which harmonic currents to flow back into other parts of the power system.
Harmonics are currents or voltages with frequencies that are integer multiples of the fundamental power frequency e.g. if fundamental frequency is 50Hz, then the 2nd harmonic is 100Hz, the 3rd is 150Hz etc.
Harmonics are having adverse effects such as overloading of transformers (de-rating) and rotating equipment, tripping of circuit breakers and fuses, neutral overloading etc.
-- I --
The areal density of the luminous flux incident at a point on a surface.
In an isolated LED driver the Input (AC side) & Output (LED side) are separated by power transformer which provides galvanic isolation. Isolated power supply transform the 110/220V AC voltage to the lower voltage by means of an isolation transformer.
-- L --
A generic term for a source created to produce optical radiation. By extension, the term is also used to denote sources that radiate in regions of the spectrum adjacent to the visible.
Light Emitting Diode (LEDs)
LEDs are solid-state semiconductor devices that convert electrical energy directly into light. LEDs can be extremely small and durable; some LEDs can provide much longer lamp life than other sources.
Single or multiple LEDs pre-mounted onto a PCB.
Average rated life (of a light source) is usually the number of hours when 50% of a large group of lamps have failed.
Radiant energy that is capable of exciting the retina and producing a visual sensation. The visible portion of the electromagnetic spectrum extends from about 380 to about 770 nanometers.
Standard International (SI) unit of luminous flux. Radiometrically, it is determined from the radiant power. Photometrically, it is the luminous flux emitted within a unit solid angle (one steradian) by a point source having a uniform luminous intensity of one candela.
the quotient of the luminous flux at an element of the surface surrounding the point, and propagated in directions defined by an elementary cone containing the given direction, by the product of the solid angle of the cone and the area of the orthogonal projection of the element of the surface on a plane perpendicular to the given direction.
-- N --
In a non-isolated LED driver, there is no power transformer. Non-isolated refers that output terminal and the input terminal are directly electrical connected.
-- P --
The measurement of quantities associated with light. Photometry may be visual, in which the eye is used to make a comparison, or physical, in which measurements are made by means of physical receptors.
-- R --
Reactance is a measure of opposition to a sinusoidal alternating current that arises from the presence of inductance and capacitance within a circuit.
The ratio of the reflected flux to the incident flux.
-- S --
An SMD LED Module (surface-mount device light-emitting diode module) is a type of LED module that uses surface-mount technology (SMT) to mount LED chips on printed circuit boards (PCB).
A pictorial representation of the radiant power emitted by a light source at each wavelength or band of wavelengths in the visible region of the electromagnetic spectrum (360 to 770 nanometers).
-- T --
Total Harmonic Distortion
Total harmonic distortion is a measure of the harmonic distortion present in a signal expressed as the ratio of the sum of the powers of all harmonic components to the power of the Fundamental frequency.