| 摘要 |
<p>The present invention provides an improvement in color picture tubes (10) including an electron gun (26) for generating and directing three inline electron beams (28), a center beam (28G) and two side beams (28B,28R), along initially coplanar paths toward a screen (22) of the tube. The gun includes three spaced electrodes (38,40,42) which form an einzel lens in the path of each beam as a main focus lens for focusing the electron beams. A first einzel lens electrode (38) includes three inline cylinders (78) through which the electron beams pass. A second einzel lens electrode (40) includes a large oval cylinder (40) that overlaps all three cylinders of the first einzel lens electrode. A third einzel lens electrode (42) includes three inline cylinders (82) which are overlapped by the oval cylinder. The oval cylinder includes means (86,88,90,92) for shaping the main focus lens, to focus the three electron beams stigmatically near ground potential, and to converge the outer beams at the center of the screen.</p> |
