Design And Optical Simulation Of Phosphor Film With Tunable CCT Used In LED

For the high color temperature(CCT)and low color rendering index(CRI)of the combination of blue chip with yellow phosphor,near-ultraviolet(n-UV)chip combined with red-green-blue(RGB)phosphors,whose low luminous efficiency is a big problem in LED lighting industry,has been invented To improve this optical property,we adopted simulation and experiment methods in terms of the structure of phosphor film,comparing their luminous property of the four designed configurations of pixel-array-phosphor film,and studied the effect of the pixel size on CCT uniformity,at last a reference was introduced into experiment to compare with the sample we design before,and we obtained white LED with high luminous efficiency and uniform light emission;We altered the ratio among the RGB phosphors and designed corresponding configurations,along with varying the excitation wavelength of LED chip,realizing variable luminous color emission,and then we selected parts of phosphors film into experiment to verify the simulation results.According to the research report:(1)RGB phosphors have a suitable concentration in encapsulated glue,in which it can promise full absorption of n-UV light and as well moderate scattering behavior ability to RGB light of phosphor film.(2)Pixel-array-phosphor film can lessen the absorption behavior effectively in phosphor layer,decreasing the absorption of red phosphor to green and blue light,and green phosphors to blue light,and thereby improving the luminous efficiency of LED products.(3)RGB-phosphor-pixel size can affect the CCT uniformity of LED output light,as for the phosphors film with 4.0*4.0 mm,output light possessed better uniformity when pixel size is 0.5*0.5 mm,next is the ones with 0.1*0.1 mm and 1.0*1.0 mm,however,the uniformity of light emission is worse when the size is 2.0*2.0 mm and in this condition the sample cannot be applied into practical product.(4)For LED product to emit variable luminous color,there has two ways including adjusting the ratio of RGB phosphors and the excitation wavelength of LED chip: it is convenient to modify light emission with different colors by varying the ration of RGB phosphors,realizing tunable luminous color,and its range can cover the whole triangle region formed by chromaticity coordinates corresponding to original spectra of single RGB phosphors;Regarding different excitation wavelength of LED chip,when it located in range of 360 nm to 400 nm or 440 nm to 460 nm,variable excitation wavelength of LED chip can hardly have influence on the luminous color of final light emission,while wavelength shifts from 400 nm to 460 nm,luminous color of the output light would have a obvious shift to blue light region.LED packaged with RGB phosphors possesses high CRI,tunable CCT and improved luminous efficiency,which would be the developing direction of next generation LED.