High-color-rendering light sources consisting of a 350-nm ultraviolet light-emitting diode and three-basal-color phosphors

The high-color-rendering (HCR) potential of the light sources consisting of 350-nm ultraviolet light-emitting diodes (UV-LED) and three-basal-color phosphors was simulated and experimentally confirmed. By using an AlGaN-based UV-LED as an excitation source at the 350-nm wavelength, we measured fluorescence spectra of three-basal-color phosphors, and simulated the optimum phosphor mixture based on the Commission Internationale de l'Eclairage standard light sources D-75, D-65, D-55, D-50, C, and A, with HCR indexes (R-a) over 92. We confirmed the potential of HCR of this light source consisting of 350-nm UV-LED and three-basal-color phosphors, by obtaining R-a=86similar to89 of the incandescent type of standard light source A experimentally. Such high R-a are due to the highly monochromatic UV-LED emission and the wide spectral separation between the UV excitation (350 nm) and visible fluorescences. This combination also provides a diffusive, nonglare light source with highly steady color independent of the emission orientation. We also examined the importance of the separation between the excitation wavelength and the fluorescence emission wavelength for practical lighting applications. (C) 2003 American Institute of Physics.