An LED filament light bulb is an LED lamp which is designed to resemble a traditional incandescent light bulb with visible filaments for aesthetic and light distribution purposes, but with the high efficiency of light emitting diodes (LEDs). It produces its light by LED filaments, series-connected strings of diodes that resemble the filament of an incandescent light bulb. They are made with the same envelope shapes, with caps to fit the same sockets, and work at the same voltage as incandescent bulbs, and are direct replacements for conventional clear incandescent bulbs. They may be used for their appearance, similar when lit to an incandescent bulb, or for their wide angle of light distribution, typically 300°. They are also more efficient than many other LED lamps.
|Name||LED Track Light|
|Kelvin º||2700 / 3000|
|Life Expectancy (H)||30,000|
E-Top Structure of a typical filament
Closeup of a filament at 5% power; note the individual LED light spots.
A LED filament type design light bulb was produced by Ushio Lighting in 2008, intended to mimic the appearance of a standard light bulb. Contemporary bulbs typically used a single large LED or matrix of LEDs attached to one large heatsink. As a consequence, these bulbs typically produced a beam only 180 degrees wide. By about 2015 LED filament bulbs had been introduced by several manufacturers. These designs used several LED filament light emitters, similar in appearance when lit to the filament of a standard incandescent bulb, and very similar in detail to the multiple filaments of the early Edison incandescent bulbs.
E-Top HK LED filament bulbs were patented by Ushio and Sanyo in 2008. Panasonic described a flat arrangement with modules similar to filaments in 2013. Two other independent patent applications were filed in 2014 but were never granted. The early filed patents included a heat drain under the LEDs. At that time LEDs were under 100 lm/W (lumens of light per a single watt of electricity). In the late 2010s, available LED filaments have a luminous efficacy of up to 160 lm/W.