Dip-transfer phosphor coating on designed substrate structure for high angular color uniformity of white light emitting diodes with conventional chips.

Angular color uniformity (ACU) is one of the most important optical parameters of white lighting emitting diodes (LEDs). In this paper, we proposed a kind of phosphor coating method to enhance ACU of phosphor-converted white LEDs with conventional chips by the combination of substrate structure design and phosphor dip-transfer coating. Through this method, compact and optimal phosphor layer arrangements for high ACU can be realized. Optical simulations and experiments were conducted to examine its ACU performance. Compared with conventional phosphor dispensing coating, the present method shows very high ACU performance. Extremely small angular correlated color temperature (CCT) deviations were obtained, which are less than 200K at average CCTs ranging from 4000 K to 6000 K.