| 摘要 |
PURPOSE:To prevent any luminance difference, which might be caused due to the difference between the incidence angles of electron beams, by coating a fluorescent screen with a metal back layer the thickness of which increases further away from an electron gun. CONSTITUTION:The thickness of a metal back layer 20 is varied so that it continuously increases from the lower part of a picture surface to the upper part of the picture surface, and that the ratio of the thickness of the lower part to that of the upper part is 1 to 1.4. Since the thickness (d) of the metal back layer 20 formed on a fluorescent screen 2 is adjusted to be smaller on the lower side of the picture surface (on the side of an electron gun 4) and larger on the upper side of the picture surface (on the side distant from the electron gun 4), although the incidence angles (theta) (theta1<theta2) of electron beams increase further away from the electron gun 4, the passing routes (b1') and (b2') in the metal back layer 20 of electron beams (b1) and (b2) become the same, become the same at every vertical scanning position. consequently, the luminance of every part of the picture surface, especially in the vertical scanning direction, becomes the same, and a thicn cathode-ray tube with a good picture quality is obtained. |
