LED filament

They may be used for their appearance, similar when lit to a clear incandescent bulb, or for their wide angle of light distribution, typically 300°.

A benefit of the filament design is potentially higher efficiency due to the use of more LED emitters with lower driving currents.

A major benefit of the design is the ease with which near full "global" (360°) illumination can be obtained from arrays of filaments,[1] but two zones emitting less light appear diagonal to the substrate.

LED filament bulbs have many smaller, lower-power LED chips than other types, avoiding the need for a heatsink, but they must still pay attention to thermal management; multiple heat-dissipation paths are needed for reliable operation.

The lamp may contain a high-thermal-conductivity gas (helium) blend to better conduct heat from the LED filament to the glass bulb.

[1] LED filaments can burn out quickly if the controlled gas fill is ever lost for any reason.

[10] The simple linear regulator used by some cheaper bulbs will cause some flickering at twice the frequency of the mains alternating current, which can be difficult to detect,[8] but possibly contributes to eyestrain and headaches.