| 摘要 |
PURPOSE:To correct the focus screen of an image pickup tube and improve its aberration by causing at least two electrodes to encroach upon the target and changing the electric potentials of given areas. CONSTITUTION:Extended areas (g6) of an electrode (G6') connected to a mesh electrode encroach upon the areas (b), (d), (f) and (h) of an electrode (G5) which correspond to the four corners of the effective scanning surface 1 of a target (TA). The width of the extended areas (g6) is the widest in their center and is narrowed toward their end. The electric potential of the areas (b), (d), (f) and (h) of the electrode (G5) is higher than its other area. Accordingly, the focusing of peripheral beams corresponding to the four corners (areas b, d, f and h) of the electrode (G5) is weakened and front pins are corrected, thereby achieving improved aberration. |
