| 摘要 |
PURPOSE:To prevent any shift in convergence while eliminating influences due to the changes in neck internal wall potential and those in bead glass surface potential by connecting a bead glass conductive region to a low voltage electrode via a conductor so as to substantially block a space between a convergence electrode and a neck internal wall. CONSTITUTION:A bead glass conductive film 41 is formed on the surface of a bead glass 37 near a gap between the fifth grid 35 and the sixth grid 36 while facing to a neck conductive film 42. Thus, by providing conductive films 41, 42 respectively on a neck internal wall and the bead glass surface near the gap between the electrodes forming a primary electron lens, so as to face to each other and connecting the conductive film on the bead glass surface to a low voltage electrode via the conductor, the electric charge on the surface opposing to the bead glass electrode is stabled for a short period of time and further the potential of the neck internal wall is also stably held. Further, for example, a curl part 38a is provided on the open end side of the convergence electrode 38 to shield undesired electrons coming to the electron gun. |
