Improvement of Luminance and Luminous Efficacy of Mercury-Free, Flat Fluorescent Lamp by Optimizing Phosphor Profile

A highly efficient mercury-free fluorescent lamp (MFFL) was developed for an alternative to fluorescent lamps containing mercury. The lamp has a simple structure with two main electrodes running parallel to each other and an auxiliary electrode. In order to improve the luminance and luminous efficacy of MFFLs further, we optimized the thickness of rear and front phosphors on the inner surfaces of the lamp, and then adopted an uneven distribution profile for the rear phosphor to increase the surface area of the phosphor. The MFFL with the optimized phosphor profile showed a wide luminance range from 3315 to 17133 cd/m
²
with the corresponding luminous efficacy from 75.2 to 42.5 lm/W with the color coordinate around (0.32, 0.32) for daylight.