Preparation and properties of electroluminescent phosphors for display devices

Electroluminescent phosphors for use in some electronic display devices should have brightness-voltage characteristics differing from those used in light sources, for example. The various factors of phosphor preparation and of cell construction which affect these characteristics have been studied. Special phosphor powders with unusually high or unusually low values of "discrimination ratio" (a quantity related to the change in output as the applied voltage is varied) have been developed and their performance described. It has also been shown that thin phosphor films afford extremely high values of discrimination ratio, particularly if operated on dc. The use of nonlinear materials (especially zinc oxide) as auxiliary layers to increase the discrimination ratio obtained with a given phosphor has been studied.