摘要:
A colour display tube has an in-line electron gun for generating three co-planar electron beams first and second lens electrode produce a focusing lens field for focusing the electron beams. At least one of the lens electrodes has a correction element for tuning the astigmatism of the lens field. The correction element includes three co-linear apertures for passing the electron beams, the outer apertures of which are funnel-shaped, the wide end of the funnel-shape being directed away from the center aperture.
摘要:
Color cathode ray tube (1) device having an electron gun (6) of the in-line type for generating three electron beams (7,8,9), a display screen (10) and deflection coils (11) for scanning the electron beams over the display screen. The electron gun includes a main lens part for focusing the electron beams on the display screen, the main lens part comprising main lens electrodes (26, 27) having apertures for passing of the electron beams, at least one of said main lens electrodes comprising two sub-electrodes (26a, 26b) adjacent to each other, each of the sub-electrodes having a central (311, 321) and two outer apertures (312, 322, 313, 323), whereby in operation between the adjacent sub-electrodes an astigmatic quadrupole field is generated. For the central apertures of the sub-electrodes it holds: xQa.ltoreq.xQb and for the two outer apertures of the sub-electrodes it holds: yQa.ltoreq.yQb.