Effects of Green - Emitting Phosphor (La,Ce,Tb)PO_4:Ce:Tb on Luminous Flux and Color Quality of White LED Lamps

Anotace: In this paper, we present and analyze the influence of (La,Ce,Tb)PO_4:Ce:Tb green phosphor (LaTb) toward the performance of the multi-chip white LED (MCW-LEDs) lamps including color uniformity, lumen output, Color Rendering Index (CRI), and Color Quality Scale (CQS). By mixing the LaTb green phosphor and the YAG:Ce yellow phosphor compounding under condition of 7000 K MCW-LEDs, this new approach can produce a huge meaningful change in lumen output and the angular color distribution of MCW-LEDs. We also study the interaction between the concentration and size of the LaTb particles with output flux, color uniformity, CRI, and CQS. The obtained results demonstrate that the higher lumen output, the higher color uniformity enhancement could be attained by adding the LaTb particles with a size range around 6-8 µm and the concentration around 1.5% in phosphor layer. Meanwhile, the decrease of the color rendering value (CRI) and the Color Quality Scale (CQS) tend to be stable and insignificant. In other words, the obtained results provide a prospective method which plays an important role in the development of MCW-LED manufacturing technology.