Patent ID: 8003012

Claim:
A persistent phosphor blend comprising: at least one persistent phosphor comprising a composition selected from the group consisting of a) a composition having a general formula A x-y-z Al 2-m-n-o-p O 4 :Eu y , Dy z , B m , Zn n , Co o , Sc p , where A is Ba, Sr, Ca, or a combination of these elements, x is between about 0.75 and 1.3, y is between about 0.0005 and about 0.1, z is between about 0.0005 and about 0.1, m is between about 0.0005 and about 0.30, n is between about 0.0005 and about 0.10, o is between about 0 and about 0.01 and p is between about 0 and about 0.05, and b) a composition having general formula A x-y-z Al 2-m-n-o-p O 4 :Eu y , Nd z , B m , Zn n , Co o , Sc p , where A is Ba, Sr, Ca, or a combination of these elements, x is between about 0.75 and about 1.3, y is between about 0.0005 and about 0.1, z is between about 0.0005 and about 0.1, m is between about 0.0005 and about 0.30, n is between about 0.0005 and about 0.10, o is between about 0 and about 0.01, and p is between about 0 and about 0.05; and at least one other phosphor, wherein the excitation spectrum of the at least one other phosphor partially overlaps the emission spectrum of the persistent phosphor.