Spectrum optimization of tri-color white LEDs at fixed correlated color temperature

Luminous efficacy of radiation(K) and color-rendering index(Ra) are two important parameters of LEDs.Generally,high luminous efficacy of radiation is obtained at the sacrifice of color-rendering index.The requirement of correlated color temperature(CCT) differs for various application environments.Considering the fixed CCT of 3 000 ± 10 K,we adjusted spectrum parameters of the tri-color white LEDs,such as peak wavelength,full width at half maximum(FWHM) and relative optical power ratio,to obtain the optimum balance between luminous efficacy of radiation and color-rendering index.It turns out that with peak wavelength at 467 nm,550 nm and 618 nm,FWHM at 30 nm,71 nm and 23 nm,relative optical power ratio at 1.00∶1.90∶4.90,we achieve K=391 lm/W and Ra=92.6.Afterwards,further study was performed i.e.,the impact of spectrum parameters on CCT,luminous efficacy of radiation and color-rendering index.Results show that suitable spectrum parameters exert tremendous influence upon the obtainment of low specified CCT of spectral power distribution(SPD) of LEDs,while the optimum balance between K and Ra should be taken into account simultaneously.