| 摘要 |
PURPOSE:To lower scattering of electrons caused by the function of a color selection electrode, improve color purity of each luminous picture element and also improve contrast of screen by coating the internal wall of aperture, allowing the electron beam to pass through, of the color selection electrode with a substance having the average atomic number which is smaller than the average atomic number of a material forming the color selection electrode. CONSTITUTION:The principle that a substance having a smaller atomic number provides lesser scattering of electron is utilized. Namely, in view of easing scattering of electron due to a substance constituting the color selection electrode (shadow mask 12), a substance having the average atomic number smaller than that of said substance is used for coating the internal wall of aperture 6 where electrons are most easily scattered and thereby a scattering preventing layer 8 is provided. Since it is difficult from the technical view point to form the scattering preventing layer 8 only at the internal wall of aperture 6, it is practical to form the scattering preventing layer 8 also at the luminous screen side 4 of the shadow mask 2 simultaneously with the internal wall of aperture 6. |
