Color cathode-ray tube having a dynamic focus voltage

A color cathode-ray tube comprising a screen, three cathodes laid out on a single horizontal plane for generation of electron beams, first electrode means including a control electrode and a first acceleration electrode disposed sequentially from the cathodes for causing the electron beams to travel to the screen along initial pathways parallel to each other on the single horizontal plane, and an electron gun having second electrode means including a focus electrode portion and a final acceleration electrode for forming a main lens for use in focusing the electron beams on the screen, characterized in that

• those electrodes constituting the second electrode means of said electron gun includes a focus electrode of said focus electrode portion neighboring upon the final acceleration electrode with a maximal voltage applied thereto and being made up of a plurality of divided focus electrode members, and by comprising:
• a final-stage of the main lens being formed of said final acceleration electrode and an electrode member of said divided focus electrode members neighboring the final acceleration electrode for providing a focusing action which is stronger in a horizontal direction than in a vertical direction, with all of the divided focus electrode members constituting said focus electrode being equal in voltage potential;
• at least one electron lens of a first kind formed between said divided focus electrode members for providing a focusing action stronger in the vertical direction than in the horizontal direction and for causing the electron beams to change in profile with an increase in deflection amount thereof by applying a voltage potentially variable in synchronism with deflection of the electron beams;
• at least one electron lens of a second kind formed between said divided focus electrode members and said election lens of the second kind also formed between said final-stage of said main lens and said electron lens of the first kind for weakening the lens intensity with an increase in deflection amount of the electron beams by applying a voltage variable in synchronism with deflection of the electron beams;
• and
• an electron lens of a third kind formed of at least one electrode constituting the first electrode means of said electron gun for having a focusing action stronger in the horizontal direction than in the vertical direction.