White light-emitting phosphor - comprising zinc-sulphide-based blue phosphor and calcium sulphide-based yellow phosphor

摘要

A phosphor which emits white light essentially comprises a blue light emitting phosphor based on ZnS and a yellow light emitting phosphor based on CaS. The ZnS-based phosphor is at least one of ZnS:Ag, ZnS:Ag,Cl or ZnS:AgmGa. The CaS-based phosphor is (Ca(1-x)Mgx)S:Mn,Ce or a mixt of (Ca(1-x)Mgx)S:Ce and (Ca(1-x)Mgx)S:Mn with x greater than or equal to 0 and less than or equal to 0.5. the CaS-based phosphor contains 100-20,000 ppm Mn and 10-20,000 ppm Ce as activators. The ZnS-based phosphor contains 2-20,000 ppm Ag, 1-10,000 ppm Ga and 1-10,000 ppm Cl as activators. The ZnS/Cas mixt. ratio is 1:9 - 5:5. ADVANTAGE - Unlike conventional white light phosphors, which comprise (Zn,Cd)S and/or InBO3 as the yellow light phosphor component, the phosphor claimed here does not contain Cd, is inexpensive, has a high luminance, and has a time of afterglow which is almost as long as that of InBO3 and longer than that of (Zn,Cd)S.