| 摘要 |
PURPOSE:To improve the halo of a beam spot in the upper and lower ends of a screen and the focussing characteristics of the whole screen by arranging a high permeability magnetic piece in the beam divergence area of a compound lens. CONSTITUTION:An electron lens is a compound lens with the convergence area on the low voltage electrode side and the divergence area on the high voltage electrode side as a borderline between a low voltage electrode 3 and a high voltage electrode 4. A high permeability magnetic piece 7 is arranged inside this high voltage electrode 4 so as to concentrate the vertical deflection leak magnetic field on the high voltage electrode of a main lens, i.e. in the divergence area, to reduce its leak on the low voltage electrode side, i.e. in the convergence area, and to control axial separation in the convergence area. As a result, the halo of a beam spot in the upper and lower ends of a screen and the focussing characteristics of the whole screen can be improved. |
