| 摘要 |
PURPOSE:To provide a cathode ray tube capable of displaying a uniform picture all over the picture screen, by improving resolution of beam spots landing at the circumferential portion without sacrificing brightness. CONSTITUTION:In a cathode ray tube of electrostatic deflection type including an electron gun 10, vertical deflection plates 20, horizontal deflection plates 21, and a phosphor screen 30, an electron beam restricting electrode 11 having a non-circular aperture 11b and an auxiliary electrode 12 having a circular aperture 12a disposed on the side of the cathode of the restricting electrode 11 are provied. The auxiliary electrode 12 is provided for the following reason: while the second grid electrode 14 and the focusing electrode 13 constituting the main lens system for the electron gun 10 are required to have apertures of the same shaping, since the electron restricting electrode 13 which is also a constituent of the main lens system has a non-circular aperture 11b, a sort of lens aberration occurs. The auxiliary electrode 12 having a circular aperture 12a is therefore provided as another constituent of the main lens system for preventing the aberration from occurring. |
