| 摘要 |
PURPOSE:To enlarge the diameter of the electron beam pass hole section, by forming the electron beam pass hole section of the third grid and the fourth grid such that the central pass section is gradually projected against both side pass hole sections. CONSTITUTION:In the third grid 40 where three electron beams 14-16 arranged in parallel on a plane of an electron gun structure 6 will pass, the central electron beam pass hole section 43 is projected over both side electron beam pass hole sections 42, 44 and electron beam pass hole sections 52-54 of the fourth grid 40' is relatively projected. The inter-electrode effective border line 51 is gradually varied to be a parabola in the proximity of the central pass hole sections 43, 53 while to be a hyperbola in the proximity of both side pass hole sections 42, 52, 44, 54. Consequently a large diameter electron lens of asymmetric face is formed, and since the electron beams 14, 16 are not forcused strongly to the central portion it can be forcused well to a predetermined point on a fluorescent face. |
