| 摘要 |
A vertical electrode plate 28 having three openings 30a, 30b and 30c formed in-line through which three electron beams pass respectively is provided only inside a focusing electrode 23 out of the focusing electrode 23 and a final accelerating electrode 24. A horizontal electrode plate 29 that is substantially parallel to an in-line plane extending toward the focusing electrode 23 is formed at least one of above and below openings 31a, 31b and 31c at the bottom of a shielding cup 25, only inside the final accelerating electrode 24. By setting the height h of the horizontal electrode plate 29 optimally, it is possible to correct a horizontally-elongated distortion of a spot shape in edge portions of a screen, caused by a self-convergence magnetic field of a deflecting device. In this manner, a color display tube that achieves an image display with a high resolution can be provided. <IMAGE> |
