CCT stabilization and phosphor temperature detection in pc-WLEDs

A novel method to stabilize the correlated color temperature in pc-WLEDs from their initial turn-on state to thermal equilibrium is proposed and demonstrated. Under the normal operation condition, it can stabilize the CCT of a pc-WLED by the positive matching of the blue LED peak wavelength to the phosphor excitation spectrum. In the experiments, the CCT variation could be as small as from 7 K to 83 K in different cases. In addition, this study also proposed a practical approach for measuring phosphor temperature in an operating pc- WLED using a noncontact, instant detection method to remotely monitor the emission spectrum. The approach is also independent of the peak wavelength of pumping lights, the concentration and thickness of phosphor, and correlated color temperatures. Firstly, a novel method to stabilize the correlated color temperature in pc-WLEDs from their initial turn-on state to thermal equilibrium is proposed and demonstrated. In the experiments, the CCT variation could be as small as from 7 K to 83 K in different cases. Secondly, this study also proposed a practical approach for measuring phosphor temperature in an operating pc-WLED using a noncontact, instant detection method. The approach is also independent of the peak wavelength of pumping lights, the concentration and thickness of phosphor, and correlated color temperatures.