抄録
White LEDs with single phosphor usually have poor color rendering capability. The emission spectra of the blue LED and the yellow phosphor are narrow as compared with the reference light sources. The red light output is particular low. The color of the objects illuminated by such light source appear not accurate nor natural. Though the luminous efficiency is high, such poor color rendering light sources are not suitable for most general lighting applications. To improve the color rendering properties, multiple phosphors with different emission spectra should be used. For instance, a certain amount of red or orange phosphors may be used to mix with yellow phosphor to broaden the overall spectrum. In this paper, a numerical model is proposed to predict the emission spectra of LEDs with multiple phosphors. The model has considered the excitation and emission spectra of the phosphors, the mixing ratio and re-absorption between the phosphors. To validate the model, white light LEDs with multiple phosphors are fabricated. The spectra are measured and compared with the modeling results. It is found that the proposed model can estimate the emission spectra of LEDs with multiple phosphors with a high degree of accuracy.
