| 摘要 |
An inline electron gun for use in a multi-beam color cathode ray tube (CRT) has a main focus lens for focusing the electron beams on a display screen of the CRT. The main focus lens includes adjacent charged electrodes each having a respective common lens aperture through which the electron beams are directed and which are in facing relation for reducing horizontal spherical aberration of the electron beams on the display screen, where each common lens aperture has a longitudinal axis aligned with the inline electron beams. In one embodiment, each common lens aperture is chain-link-shaped including spaced, vertically enlarged portions, each aligned with a respective electron beam for correcting for vertical spherical aberration. Each adjacent electrode further includes a plurality of auxiliary apertures, each aligned with and passing a respective electron beam. Each auxiliary aperture includes a generally circular center portion and upper and lower slots extending generally vertically therefrom to provide balanced focusing for all of the electron beams as well as to correct for beam astigmatism. The circular center portion of each aperture is adapted to receive a cylindrical electrode support rod, or mandrel, disposed within and aligning the electrodes during electron gun assembly. The three inline auxiliary apertures may have the same diameter, or the two outer apertures may have larger diameters and wider slots than the center aperture in another embodiment. The slots may be vertically centered on the circular center portion of each aperture, or the two outer apertures may have outwardly disposed upper and lower slots in another embodiment.
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