Luminescence characteristics of mercury-free flat fluorescent lamp with arc-shape anodes

The luminescence characteristics of mercury-free flat fluorescent lamp (FFL) with arc-shape anodes utilizing dielectric barrier discharge were investigated by comparing its luminance uniformity with that of the conventional FFL with beeline-shape anodes and measuring the variation of its luminance and luminous efficacy with discharge gap, dielectric thickness, xenon concentration and total gas pressure of mixture gas. The experimental results show that the steady diffusive micro-discharge can be obtained at a high gas pressure even near to 1 atmosphere pressure when the narrow pulse-width voltage waveform is applied, and the luminance and luminous efficacy can both be improved with the increase of discharge gap, whereas the luminous efficacy rises and gradually reaches to a saturation value with the increase of dielectric thickness. Under the driving pulse with frequency of 65 kHz and peak voltage of 2.2 kV, the novel FFLs with a diagonal size of 12 inches demonstrate the luminance of over 6400 cd/m², luminous efficacy of over 22 lm/w, and luminance uniformity of over 86%.