Optimization of four-primary white LEDs based on protective effect and color quality-a solution for museum illumination

A solution was proposed for obtaining white light-emitting-diodes (LEDs) which are suitable for illuminating traditional Chinese paintings painted with inorganic pigments (iop-TCPs) based on the requirements of protective illumination and color quality. The damage laws and degrees of 450nm, 510nm, 583nm, and 650nm monochromatic lights which can construct four-primary white LEDs on the iop-TCPs were obtained through long-term illumination experiment and data analysis by converting color coordinates into CIE DE2000 color difference values. Then we obtained the damage formula of the constructed white LEDs, which can be used to evaluate damage degree. Spectral power distributions (SPDs) of the white LEDs, which can be iterated by brute-force algorithm, were simulated by the Gaussian formula. Constructed SPDs were evaluated by the damage formula and color quality formulas. The color quality eligible white LEDs with higher correlated color temperatures (CCTs) damage less to iop-TCPs. And the lowest damage SPDs satisfying color quality requirements in CCT ranges from 2700K to 4000K were obtained. Achievements can provide the theory and application basis for manufacturing white LEDs suitable for illuminating iop-TCPs; and the method can be further used in preparing white LEDs applicable to other cultural relics.