Influence of Phosphor Particle Size on Visual and Non-Visual Performances of White Light-Emitting Diodes for General Lighting

We perform an investigation on the influence of phosphor particle size on visual and non-visual performances of white light-emitting diodes (LEDs) applied in the healthy general lighting. These studied white LEDs with a chip-scale packaging (CSP) structure are consisted of blue, green, and red phosphors, which are pumped by 365 nm near-ultraviolet LEDs. The monte carlo ray tracing based optical simulation and Mie scattering theory in LightTools softwares are adopted in this study. After optical simulation and spectral calculation, the circadian action factor (CAF) and other relevant parameters are deduced from spectral power distributions of white LEDs. Finally, the micro hyper-spectral imaging technique is employed for detecting micro-level luminescences of large (diameter $D$ = $20 ~\mu \text{m}$ ) and small ( $D$ = $10 ~\mu \text{m}$ ) phosphor particles, indicating that small phosphor particles would scatter more light than large ones, leading to low luminous output and low CAF at the same time.