| 摘要 |
468,238. Luminescent screens for electric discharge tubes. GENERAL ELECTRIC CO., Ltd. (Patent-Treuhand- Ges. fur Elektrische Gl³hlampen) Jan. 3, 1936, No. 297. [Class 98 (i)] [Also in Group XL] The screen is prepared by coating several layers of the same or different luminescent materials on a support, the grain-size of the material in any layer being smaller than that in the next superimposed layer, and the layers being attached by a binder consisting of phosphoric acid or its analogues containing arsenic or antimony, as described in Specification 460,756. Each layer is dried by heat before next is applied. In an example, on the glass envelope of a discharge tube are applied three layers of zinc silicate, of grain size 1-10Á, 10-40Á and 40-80Á respectively. A composite screen with a lower layer of zinc silicate, and an upper layer of calcium tungstate is referred to. Reference is made also to layers of cadmium silicate, zinc sulphide, and magnesium tungstate or mixtures thereof. The uppermost layer may be protected from the discharge by a layer as of powdered quartz, which is transparent to the radiation exciting luminescence of the screen, the layer being applied by means of the same binder. The support may be coloured. |
