Multi-chip dynamic white light emitting diode with high level photobiological safety and good color fidelity

Abstract

Blue light hazard has been the main concern of photobiological safety of light emitting diode (LED) and blue light hazard efficiency of radiation (BLHER) is used to evaluate the extent of blue light hazard. In this work, we used four monochromatic LEDs with the color of purple, azure, green, and red to mix light without blue LED, in order to reduce the BLHER of hybrid white light. Also, the mixed white light kept high level of color fidelity when the correlated color temperature (CCT) ranges from 2700 to 7000 K. Color rendering index (CRI), color fidelity score (Rf), and color gamut score (Rg) are used to evaluate the color fidelity. We simulated the spectrum and parameters of hybrid white light based on different peak wavelengths, full width at half maxima (FWHMs), and relative ratios of four LEDs. Finally, we fabricated a four-channel LED to obtain tunable white light with high level of photobiological safety and good color fidelity, which BLHER is 0.185 at 7110 K, CRI, Rf and Rg are larger than 85.0, 78.7 and 87.4, respectively.