Color cathode ray tube with subelectrodes

Color cathode ray tube device having an electron gun of the in-line type for generating three electron beams, a display screen and deflection means for scanning the electron beams over the display screen, wherein the electron gun comprises a main lens part for focusing the electron beams on the display screen, said main lens part comprising main lens electrodes having apertures for passing of the electron beams, at least one of said main lens electrodes comprising at least two sub-electrodes adjacent to each other, each of the sub-electrodes having a central and two outer apertures, whereby in operation between the adjacent sub-electrodes a quadrupole field is generated, characterized in that 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
• and additionally at least one of the following relationships (a) and (b) holds:
• (a) for the sub-electrode remote from the main lens. yQa for the outer apertures is less than yQa for the central aperture, and (b) for the sub-electrode adjacent to the main lens. xQb for the central aperture is less than xQb for the outer apertures,
• wherein:
• xQa is the width of the aperture in the horizontal direction in the sub-electrode remote from the main lens,
• xQb is the width of the aperture in the horizontal direction in the sub-electrode adjacent to the main lens
• yQa is the height of the aperture in the vertical direction in the sub-electrode remote from the main lens and
• yQb is the height of the aperture in the vertical direction in the sub-electrode adjacent to the main lens.