RESUMO
This study examines three different types of laser carriers, including the phosphors in silicone (PiS), the phosphor in glass (PiG), and alumina-based ceramic binders (CP), for laser-phosphor lighting characterizations via a laser projector light source module. The thermal influence of heat spreading on these phosphor materials and their luminescence performance is also investigated. The conversion efficiency of PiS, PiG and CP was found to be 29.7%, 34.6% and 31.8%, with their corresponding maximum laser power operations of 3.9 W, 7.9 W, and 17.2 W, respectively. This work further correlates the maximum laser operation power with the thermal conductivity of luminescence material. From the optical engine perspective, it was found that CP exhibits the superior thermal conductivity of 17.0 W/mâ K for slight hot-spot IR observation and higher laser power operation. This work finally delivers a CP device for 50.2W maximum laser operation with the operating temperature below 100 °C. The simulation is also carried out in order to examine spreading resistance's influence, when subject to convective boundary condition. CP's response sensitivity to heat transfer coefficient was found to be rather small.
RESUMO
The gas discharge and photo-luminance properties of a planar lighting source featuring highly uniform light emission and mercury-free design were studied. The current density-voltage characteristics and the associated gas discharge of the devices operating with the values of the ratio of electric field to gas pressure (E/p) between 4.3 kV/Torr-cm and 35.7 kV/Torr-cm indicate that the width of the cathode fall extends over the entire gap between the two electrodes and the device is mostly in the obstructed discharge regime. The optical emission analysis confirmed the electron collision-induced gas emissions and strong effect of gas pressure on the phosphor emission when operated at constant current density, both are indicative of the primary roles played by the electron energy.