| 摘要 |
A luminescent screen comprises superimposed layers of a first phosphor, a non-luminescent material, and a second phosphor, the nonluminescent material being formed by poisioning a surface of one of the phosphor layers. The screen may be built up of a stack of continuous layers (Fig. 3, not shown), or it may be coated with a layer of phosphor particles, each particle being multi-coated, and may be used in a colour television display tube, with one or more electron guns, the energy of the electron beam determining the beam's penetration, and hence the colour emitted. In an example, a blue-emitting silver activated zinc sulphide is surface poisoned by coating with a nickel sulphide and firing, and is then coated with a second, green-emitting phosphor layer, a separator layer and finally a red-emitting phosphor layer. Numerous classes of phosphor are mentioned, poisoned by iron, cobalt or nickel, and separator materials mentioned are silica, titanium dioxide, mica, bentonate, talc and vanadium oxide. |
