| 摘要 |
PURPOSE:To improve picture quality by specifying the distance from a fluorescent surface to a lens tip and the distance from the lens tip to a screen, and arranging lens groups having specific characteristics. CONSTITUTION:When an (x)-inch size screen is used, the distance from the fluorescent screen to the lens tip is set <=140X(x)/45(mm.) and the distance from the lens tip to the screen is set to <=900X(x)/45(mm.). Four lenses are used for this screen. Namely, the 1st lens which provides convergence in the center part and divergence at the periphery, the 2nd convex meniscus lens, the 3rd concave lens, and a brown glass lens having such a fluorescent surface that the center of curvature is on the screen side in the center and increases or moves to an electron gun according to the distance from the center to the periphery are arranged successively from the screen side. |
