ABSTRACT
First, a high-viscosity solution is prepared by dissolving a binding agent in an organic solvent or deionized water in a concentration range of 0.5 to 3.0 wt%. This solution is called a vehicle.1 A phosphor suspension prepared by dispersing phosphors in the vehicle is used as a coating solution. Further, an adhesive additive from 1 to 5 wt% of the phosphors is added to the suspension to obtain better adhesion of the phosphor layer to the inner surface of glass tubes.
