ACU Enhancement of WLEDs Realized by Multilayer Phosphor With Convex Shape

A new package structure with three convex phosphor layers is shown to enhance the angular color uniformity based on modeling and experimental verification. The color uniformity has been improved by tailoring the phosphor concentration distribution of the three layers. The experimental measurements indicate that the deviation of angular correlated color temperature (CCT) can be reduced from 152.9, 487.2, and 586.4 K to 51.3, 55.1, and 78.7 K compared with the conventional structure at the average CCT of 4500, 5500, and 6200 K, respectively. Luminous flux and optical output power of LED packages with optimized multilayer phosphor have been measured and are reduced no more than 5% compared with the single phosphor layer packages.