Color-picture tube having a supplementary electrode for obtaining a high resolution picture

A color-picture tube comprising:

• a convergence electrode, to which a focusing voltage is applied,
• a final accelerating electrode, to which an anode voltage is applied, and
• at least one supplementary electrode having an electric potential responsive to said convergence electrode and said final accelerating electrode, said supplementary electrode placed between said convergence electrode and said final accelerating electrode and arranged coaxially with said convergence electrode and said final accelerating electrode so that said supplementary electrode forms a lens-electric-field which is common to three main-lens electric fields formed between said convergence electrode and said final accelerating electrode,
• wherein, each of said convergence electrode, said supplementary electrode and said final accelerating electrode comprises a tube having an elliptical cross section, and
• each of the tube of said convergence electrode and the tube of said final accelerating electrode has an elliptical end plate having three holes arranged in-line for electron passage, and in at least one of the tube of said convergence electrode and the tube of said final accelerating electrode, said end plate is positioned away from the opening of said tube closer to said supplementary electrode.