In this article

all the white LEDs are obtained from the GaN-based blue emitter plus a cerium doped yttrium aluminum gargnet (YAG:Ce) phosphor.Here we brought up a new method.Under certain ideal condition

we have rough estimated the color coordinates and the luminous flux about the white light LEDs with the new method.The color coordinates of the referenced white spectrum is (0.325

0.332)

the color rendering index is 81.5 and the color temperature is 5 914 K.All the parameters of the referenced white spectrum are similar to the standard white LED spectrum of (0.33

0.33).Based on the referenced spectrum

we simulated it and got the radiation intensities of the blue chip and the phosphor independently.By adjusting the proportion of the radiation intensities of the blue chip and the phosphor

we got some new white LED spectra.And here we defined the luminous flux of the referenced spectrum is 100 lm and the total photons of all the white LEDS is equal to the referenced white LED spectrum.Also the conversion efficiency is supposed to 100%.In the range of (

x

y

)= [0.33

0.33](±0.05)

we calculated the luminous flux of different color coordinates around the standard point.We find that the color coordinate of the maximum lumi-nous flux is at (0.35

0.38)and the luminous flux is 112 lm

the color coordinate of the minimum luminous flux is at (0.29

0.28)and the luminous flux is 93.5 lm.So we can know that the luminous flux dispersion can reach about 18.5% relative to the referenced point 100 lm.From the above results

when the luminous flux becomes the main parameter of all the white LEDs’parameters

we can know that if we want to get higher luminous flux white LEDs

we should control the quantity of the phosphor to make the color coordinate around the point (0.35

0.38).Another experiment has been done too in this article.According to the data in the experiment

the changing trend that the luminous flux increases with the increasing of color coordinate is inosculated to the calculated results.And we also find that the luminous flux dispersion 28.1% is much larger than the calculated result

so the controlling of the color coordinate becomes more important.The main reasons of the different dispersions between theoretical calculation and experiment have been concluded as follows: First

the quantum conversion efficiency is supposed to 100% in the calculation

but it can’t reach in the experiment.Second

the blue chips are different types and even they are from the same silicon slice

they can’t be the same completely.Third

the unavoidable errors that exist in the experiment influence on the results.