COLOR PICTURE TUBE

PURPOSE:To allow the correction or the comatic distortion by arranging specific circular arc-shaped flat plates on the periphery of outside electron passing holes. CONSTITUTION:A center electron beam passing hole 2g is arranged at the center of the inside bottom of a cylindrical shield cut 1, and outside electron beam passing holes 2r, 2b are arranged centering the hole 2g on a straight line outside it. Circular arc-shaped flat plates 3, 3 are arranged axially symmetrically on the inside bottom of the cup 1 around the holes 2r, 2b respectively. The flat plate 3 is made of a material of 78%Ni-22%Cr, for example, with the high relative permeability and a thickness of about 0.1-0.4mm and has 90 deg. notch sections outside the arranged positions respectively. Accordingly, the green raster, red raster, and blue raster nearly match, and the comatic distortion can be suppressed to the minimum.