Color cathode ray tube with coma reduced

Abstract

A color cathode ray tube having electron gun with a plurality of electrodes for generating and focusing three in-line electron beams toward a phosphor screen. A deflection device is mounted between a funnel portion and a neck portion for deflecting the three electron beams in horizontal and vertical directions, and a convergence correction device including a plurality of magnetic pieces positioned with respect to the three electron beams in an in-line direction of the three electron beams in magnetic deflection fields generated by the deflection device. The plurality of magnetic pieces include at least one first magnetic piece positioned on a neck wall side of side electron beams of the three electron beams in in-line direction and at least one second magnetic piece positioned with respect to a center electron beam of the three electron beams in the in-line direction, and the plurality of magnetic pieces are configured so as to locally modify the magnetic deflection fields and to make three rasters formed on the phosphor screen by the three electron beams coincident with each other. The at least one first magnetic piece has a portion of an axial length greater than an axial length of the at least one second magnetic piece, and the axial lengths are measured in a plane containing the in-line direction and a longitudinal axis of the color cathode ray tube.