| 摘要 |
PURPOSE:To perform the rough adjustment of convergence easily by providing a magnetic board having long and short diameters in a field generating means for generating a beam focusing field between magnetic yokes then rotating it. CONSTITUTION:The electron beam from a cathode 2 is focused by the first and third grids 3, 4 then accelerated by a magnetic yoke 5 to reach to a fluorescent face 14. While the magnetic yoke 5 will absorb the flux from a permanent magnet 8 to produce a focusing field at the gap section to form a magnetic main lens. Furthermore a magnetic board 19 having long and short diameters and perpendicular with the axis is provided at the fluorescent face side of the permanent magnet 8, then it is rotated around the axis to fix in random direction thus to perform the rough adjustment of convergence. Consequently the convergence can be adjusted easily without requiring the adjustment of four pole field generator 15. |
