| 摘要 |
PURPOSE:To improve the focus performance of a power-saving type color picture tube with a small neck by constituting a main lens section with the first, second, and third focus electrodes in that order from the radiation source side and applying the higher voltage in sequence to the focus electrodes apart from a cathode. CONSTITUTION:The second electrode 22 uses a deep-drawing cap-like member having a bottom section on the side facing the first electrode 21, the bottom section is bored with an electron beam pass hole 25 with nearly the same diameter as that of the electron beam pass hole bored on the first electrode 21, and an electron beam pass hole 26 with the same diameter as that of the electron beam pass hole of the second focus electrode 23 is provided on the side facing the second focus electrode 23. For example, about 150V is applied to a cathode 20, the ground potential to the first electrode 21, 1kV-2kV to the second electrode 23, about 8kV to the second focus electrode 23, and about 25kV to the third focus electrode 24 respectively. The potential distribution curve 42 of a portion corresponding to the second electrode 27 has a flat portion 421, thereby the first bi- potential lens 28 having a large aperture and extremely small spherical aberration can be formed with the second electrode 22 and second focus electrode 23. |
