Optical and electrical properties of a spiral LED filament

Abstract

This paper introduces a new type of spiral white light-emitting diodes (WLED) filament with high luminous efficiency and uniform optical performance. The optical and thermal properties of the flexible filament were investigated at different stretching heights, namely 0, 1, 2, and 3 cm. The results indicated that the filament showed the best optical characteristics at the stretching height of 2 cm, because of good heat dissipation. In addition, the radiation temperature of the filament was inversely proportional to the output luminous flux. The reliability of the filament at a stretching height of 2 cm was also evaluated after 1000 h of use. The result demonstrated that the luminous flux decay of the bulb was only 0.85%. The flexible spiral WLED filament exhibiting high luminous flux and good reliability could be adapted to promote industrial development in the near future.

The Effect of Different Filament Arrangements on Thermal and Optical Performances of LED Bulbs

“…To increase the flow of gas inside the bulb, Xu [24] et al used ionic wind to improve the heat dissipation ability of LED filament bulb. It was also necessary to consider the optical and thermal properties with various currents [24][25][26]. Nevertheless, they did not study the effect of different filament arrangements on the thermal and optical performances, nor did they design and simulate the temperature distribution and gas flow path inside the bulbs, so it was worthwhile to analyze the thermal and optical performances during the operating time.…”