| 摘要 |
PURPOSE:To reduce lens aberration and improve deflection sensitivity of the captioned tube while checking surface leakage thereof by a method wherein a mesh electrode, which is to be arranged between the final focusing electrode and the target electrode, is provided with a ring-shaped part while the ring-shaped part is fixed to the metal cylindrical body coaxially attached to the outer peripheral surface of a focusing electrode through a ring-shaped insulator. CONSTITUTION:A ring-shaped insulator 17 consisting of alumina porcelain or the like is so constituted as to have the thin thickness part 17a making contact only with the final focusing electrode 1 on the opening end edge on one side and the thin thickness part 17b making contact only with a metal cylindrical body 3 on opening end edge on the other side. Further, the metal cylindrical body 3 is so made as to have an appropriate number of wart-shaped projections 3a as well as the cut up part 3b making contact with the opening end surface on one side and the opening end surface on the other side respectively of the ring-shaped insulator 17. Accordingly, steps are produced on both ends of the ring-shaped insulator 17 so that surface leakage and creeping discharge can be almost eliminated while lens aberration can be reduced by enlarging the diameter of the electrode and deflection sensitivity can be improved by reducing the diameter of an envelope. |
