Color cathode ray tube

A color cathode ray tube comprising:

• an electron gun including an electron beam generating portion arrayed in a horizontal direction for generating three electron beams, and a main lens for focusing said three electron beams from said electron beam generating portion upon a fluorescent face, said electron beam generating portion and main lens being arrayed along an axis of the cathode ray tube;
• and
• a deflection yoke for scanning said three electron beams upon said fluorescent face;
• said main lens including
• an accelerating electrode for being supplied with an accelerating voltage and having three electron beam passages including a central electron beam passage and side electron beam passages;
• a focusing electrode for being supplied with a focusing voltage and having three electron beam passages including a central electron beam passage and side electron beam passages;
• a final stage of said main lens being formed between said focusing electrode and said accelerating electrode;
• said focusing electrode being divided into at least two focusing electrode parts, said at least two focusing electrode parts including a first focusing electrode part located at a cathode side, and a second focusing electrode part located at a fluorescent face side;
• wherein one of said first focusing electrode part and said second focusing electrode part is applied with one of a first focusing voltage and a second focusing voltage, and said second focusing voltage is a combination of a static voltage and a dynamic voltage changing according to the deflection of said electron beams;
• wherein a quadrupole electron lens is formed for each of said three electron beams between said first focusing electrode part and said second focusing electrode part, and a diverging lens force in a vertical direction of the quadrupole electron lens for the central electron beam is different from a diverging lens force in the vertical direction of the quadrupole electron lens for the side electron beams;
• wherein said first focusing electrode part and said second focusing electrode part have an opposing side, and said opposing side of one of said first focusing electrode part and second focusing electrode part has an aperture for the central electron beam and apertures for the side electron beams, and a vertical dimension of said aperture for the central electron beam is different from a vertical dimension of said apertures for the side electron beams;
• and
• wherein said focusing electrode which together with said acceleration electrode has said final stage of said main lens formed therebetween has a single aperture having a diameter which is larger in a horizontal direction than a diameter thereof in the vertical direction, and said focusing electrode has an electrode plate with an central electron beam aperture.