| 摘要 |
1,172,129. Cathode-ray tubes. HUGHES AIRCRAFT CO. 11 Aug., 1967 [3 Oct., 1966], No. 37034/67. Heading H1D. [Also in Division C1] A cathode-ray tube viewing screen comprises a light transparent glass face-plate 30 with, on the side which will form the inner surface, a coating 32 of glass having light absorbing particles randomly dispersed therein, a layer 35 of luminescent phosphor and a layer 36 of electron-pervious light-reflective material overlying the previous layers. An electrically conductive coating 44 may first be deposited on the glass face-plate 30. The light absorbing particles are preferably of manganese dioxide, but other materials may be used, such as lead oxide, boron oxide, silica, cobalt nitrate, cobalt oxide or iron oxide. Particles of colouring matter may be added to restrict the passage of light of certain wavelengths. To give areas of differing light transmittance, the coating 32 may be in two layers and the top layer incorporates, for example, dichromate ions or other material photo-sensitive to ultra-violet light and the top layer is dried, masked, exposed to ultra-violet light and the unexposed parts removed by washing to leave projecting portions 34 in a desired pattern. The layer 32 and projections 34 are then fused to leave light transmissive areas 38 and non-transmissive areas 40. |
