| 摘要 |
PURPOSE:To normally maintain the visibility of the picture image surface by forming a conductive transparent film layer on the outer surface of the display screen of the cathode-ray tube. CONSTITUTION:A conductive transparent film layer 6 formed on the outer surface of a glass 2 corresponding to the display surface of a cathode-ray tube 8 is obtained by evaporation of a highly transparent conductive metal such as tin oxide or indium oxide on the surface of the glass 2. The surface of the vacuum-side fluorescent film 3 of the glass 2 is negatively charged with a focusing beam 1. Positive charges produced on the outer surface of the glass 2 are eliminated by earthing the transparent film layer 6. Therefore, the outer surface of the glass 2 corresponding to the display surface of the cathode-ray tube 8 is constantly charged or free of charge, thereby preventing the outer surface from being contaminated by adsorbed atmospheric dust and normally maintaining the visibility of the picture image.
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