To provide a phosphor which simultaneously realizes long life and white luminescence without using an environmental load substance.
This phosphor is prepared by mixing two kinds of phosphors containing neither sulfide nor cadmium. A phosphor of the first group represented by ZnGa2O4 (blue), containing neither sulfide nor cadmium, and emitting light with a shorter wavelength than green and a phosphor of the second group represented by (Zn, Mg)O:Zn, Li (yellow) and emitting light with a longer wavelength than yellow are mixed. From the change in residual emission rate with emission time, it is found that the life of the phosphor present is longer than that of a conventional one. The mixing ratio of the two kinds of phosphors, ZnGa2O4- to (Zn, Mg)O:Zn, Li giving a fluorescent display tube which exhibits such luminescence as to be regarded as white luminescence is in the range of (9/1) to (5/5).
KITAGAWA KAZUNORI
TANAKA KAZUYUKI
