荧光粉浓度和电流强度对白光LED特性的影响

Influence of Phosphor Concentration and Current Intensity on Phosphor-Based White LED Characteristics

讨论了荧光粉浓度及驱动电流强度对白光LED特性的影响。采用软件模拟实验和实际封装测试相结合的研究方法进行分析研究。对荧光粉浓度变化对白光LED光通量和相关色温(CCT)的影响进行了三维光线追迹模拟,并且进行了实际的封装验证。另外对白光LED的节温和显色性也做了深入细致的研究。研究结果表明:CCT随着荧光粉浓度的增大而减小,光通量则先上升后下降。同时由荧光粉浓度和驱动电流强度变化所引起的节温升高会降低荧光粉的转换效率。对显色性而言,采用高浓度荧光粉封装的白光LED有相对低的显色指数;并且显色指数随着驱动电流强度的增加而升高,最终趋于稳定。

LED packaging is crucial for the development of solid-state lighting. The common method of making WLED is to mix the blue light from the LED die and the wavelength converted yellow light from the phosphor layer. We discuss the influence of phosphor concentration and drive current intensity on white LED characteristics. Software simulations and real packagings are adopted for the study. Influences of phosphor concentration on luminous flux and correlated color temperature （CCT） for white LED are investigated with three-dimensional ray tracing simulations and the results are verified by real packaging. In addition, junction temperature and color rendering of white LED are also investigated. The results show that CCT decreases with the increase of phosphor concentration, however, luminous flux achieves an optimal value and then decreases. The increased junction temperature caused by phosphor concentration and drive current intensity change degrades the phosphor conversion efficiency. For the color rendering of white LED, a higher phosphor concentration leads to a lower color rendering index, and the color rendering index increases with the increase of drive current intensity till it achieves stabilization.