LED lamp (LED light bulb)
An LED lamp (LED light bulb) is a solid-state lamp that uses light-emitting diodes (LEDs) as the source of light. The LEDs involved may be
conventional semiconductor light-emitting diodes, organic LEDs (OLED),or polymer light-emitting diodes (PLED) devices.
LED lamps can be made interchangeable with other types of lamps. Assemblies of high power light-emitting diodes can be used to replace incandescent or fluorescent lamps. Some LED lamps are made with identical bases so that they are directly interchangeablewith incandescent bulbs.
Since the luminous efficacy (amount of visible light produced per unit of electrical power input) varies widely between LED and incandescent lamps
LED lamps offer long service life and high energy efficiency, but initial costs are higher than those of fluorescent and incandescent lamps.
Life cycle of LED lamps is multiple compared to incandescent lamps, however,degradation of LED chips reduces luminous flux over life cycle as
with conventional lamps.
Size and EfficiencyLEDs measure from 3 to 8 mm long and can be used singly or as part of an array. The small size and low profile of LEDs allow them to be used in spaces that are too small for other lightbulbs. In addition, because LEDs give off light in a specific direction, they are more efficient in application than incandescent and fluorescent bulbs, which waste energy by emitting light in all directions. |
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Long LifeThe life of a high-power white LED is projected to be from 35,000 to 50,000 hours, compared to 750 to 2,000 hours for an incandescent bulb, 8,000 to 10,000 hours for a compact fluorescent and 20,000 to 30,000 hours for a linear fluorescent bulb. LED lifetimes are rated differently than conventional lights, which go out when the filament breaks. Typical lifetime is defined as the average number of hours until light falls to 70 percent of initial brightness, in lumens. LEDs typically just fade gradually. |
Lower TemperaturesConventional lightbulbs waste most of their energy as heat. For example, an incandescent bulb gives off 90 percent of its energy as heat, while a compact fluorescent bulb wastes 80 percent as heat (see References 4). LEDs remain cool. In addition, since they contain no glass components, they are not vulnerable to vibration or breakage like conventional bulbs. LEDs are thus better suited for use in areas like sports facilities and high-crime locations. |
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EnergyStar LEDsPoorly designed LEDs may not be long-lasting or efficient. LEDs that are EnergyStar-qualified should provide stable light output over their projected lifetime. The light should be of excellent color, with a brightness at least as great as conventional light sources and efficiency at least as great as fluorescent lighting. The LEDs should also light up instantly when turned on, should not flicker when dimmed and should not consume any power when turned off. |
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