| 摘要 |
<p>A colour cathode ray tube having an integrated electron gun structure including mirrored main focusing and accelerating electrodes (46B, 52). The electron gun comprises a triode section formed by three in-line arranged cathodes (27, 28, 29) and first and second grid electrodes (30, 36) whose apertures are symmetrically disposed about respective central (21) and outer (32, 34) axes which pass through their respective cathodes. A prefocusing electrode (38) having eccentric outer apertures is positioned next to the second electrode (36). The field produced by the prefocusing electrode (38) serves to converge the electron beams prodeuced in the triode section. At least one, but more conveniently two, further electrode(s) (40, 46A) are provided between the prefocusing electrode (38) and the main focusing lens electrode (46B). The outer apertures (say the apertures 44) of at least one of the further electrodes are elongated to provide an asymmetrical lens field which is used to neutralise spot errors, beam displacement and beam asymmetry. The shapes of the elongated apertures (44) are such that at a portion of their peripheries are concentric about the axes (32, 34).</p> |
