The Exit Light Co. / Knowledge Base
Types of Illumination
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One common feature of all of our signs and lights is that they require some sort of method of illumination. In order to meet established guidelines for emergency signage, exit and emergency signs need to be either internally illuminated or be able to provide illumination for up to 90 minutes.
General Concepts of Illumination
In general, each one of our signs or lights provides illumination via heat, electrical energy, or sub-atomic motion:
- Incandescence produces light by heating a substance
- Electroluminescence produces light as a result of an electric current passed through a substance
- Cathodoluminescence produces light as a result of being struck by an electron
- Photoluminescence produces light as a result of absorption of photons
- Fluorescence produces light in which the emitted photons are of lower energy than those absorbed
- Phosphorescence produces light via fluorescence slightly delayed after initial absorption of radiation
- Radioluminescence produces light as a result of bombardment by ionizing radiation
The means of illumination for each of our products is detailed with an "Info Icon" on the PRODUCT description page. The meaning of these Illumination "Info Icons" are detailed below, along with the "Pros" & "Cons" for each.
Methods of Illumination "Info Icons"
| Method | Examples | Pros | Cons |
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 Cold CathodeCold Cathode lamps produce light via the fluorescence that occurs when a phosphor coating in a glass tube is excited by UV radiation from a mercury arc. Cold cathode lamps are similar to fluorescent lamps, although in fluorescent lamps the cathode is a hot or incandescent filament. In a cold cathode lamp, the cathode is not electrically heated. |
Examples include: Cold Cathode Fluorescent Lamps (CCFL) & Neon Lamps. |
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 ElectroluminescentElectroluminescent lighting is produced when an electric current or strong electric field is passed through certain materials (usually a semiconductor). |
Examples include: Light Emitting Capacitors (LEC) & Light Emitting Diodes (LED). |
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 FluorescentFluorescent lamps produce light via the fluorescence that occurs when a phosphor coating in a glass tube is excited by UV radiation from a mercury arc. They operate similarly to cold cathode lamps, although in fluorescent lamps the cathode is a a hot or incandescent filament. |
Examples include: Linear Fluorescent Lamps (LFL) & Compact Fluorescent Lamps (CFL). |
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 HalogenHalogen lamps also produce light via incandescence. However halogen lamps have greater efficiency and longer life span. This is because the filament is surrounded by a halogen gas which allows the filament to operate a higher temperature (producing more light) and also protects the filament against "filament evaporation". |
Examples include: MR16 & PAR Sealed Beam Lamps. |
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 High Intensity Discharge (HID)High Intensity Discharge (HID) lamps produce light from the electric arc discharge which occurs when the gas and metal salts in a transparant arc tube are ionized by pulsing a high voltage across the lamp between two tungsten electrodes. HID lamps are much more lumen efficient than fluorescent or incandescent lamps as a greater proportion of their radiant energy is visible light. |
Examples include: Mercury Vapor Lamps, Metal Halide Lamps, Ceramic Metal Halide, High Pressure Sodium Lamps, Low Pressure Sodium Lamps, & Xenon Short-Arc Lamps. |
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 IncandescentIncandescent lamps produce light through the emission of the visible portion of electromagnetic radiation produced from a hot filament (literally light from heat). Incandescent lights are highly inefficient, as only a fraction of the radiation falls in the visible spectrum (most of the radiation is emitted in the infrared part of the spectrum). |
Examples include: Any lamp or bulb in which a filament produces light when heated by current. |
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 Induction (Electrodeless)Induction (Electrodeless) lamps are so named because an induction coil generates an electromagnetic field that excites mercury gas to produce UV radiation. This UV radiation, in turn, fluoresces the phosphor coating of the lamp to produce light. Although the operation of this lamp is similar to fluorescent lamps, these lamps have no cathodes (thus, no electrodes). |
Also known as: Electrodeless Lamps. |
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 Light Emitting Diode (LED)Light Emitting Diode (LED) are a subset of electroluminescent lamps. An LED is a type of solid-state diode that emits light when voltage is applied. |
Examples include: LED Exit Signs & LED Emergency Lighting. |
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 NeonNeon lamps are a subset of cold cathode lamps, as neon lamps rely on the cathodoluminescence of gas molecules for illumination. In neon lamps, the excitation of gas molecules of neon or argon produces light. |
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 PhotoluminescentPhotoluminescent products produce illumination by absorbing, and then re-emitting photons. The source of the absorbed radiation is ambiant light (sources of 5-ft candles of fluorescent, metal halide, or mercury vapor light are recommended). Phosphorescence is a specialized form of photoluminescence in which the trapped energy is "slowly". |
This type of illumination is displayed in: Glow-in-the-dark Signs, Tape & Markings. |
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 RadioluminescentRadioluminescent products produce illumination when a radiation particle, such as an electron emitted from gaseous tritium through beta decay, collide with an atom or molecule in a phosphor material, exciting an orbital electron to a higher energy level. This interaction creates fluorescent light. |
This type of illumination is displayed in: Self-Luminous or Tritium Exit Signs. |
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