Color cathode ray tube apparatus to modify deflection magnetic fields

摘要

In a cathode ray tube apparatus having an in-line type electron gun, magnetic pole pieces comprising four pole pieces of substantially arc-shaped cross section are disposed in a cylindrical shape with circumferential gaps between neighboring pole pieces 0 DEG , 90 DEG , 180 DEG , and 270 DEG locations on the cylinder. An additional pair of narrow width stripe-shaped pole pieces are disposed inside said cylinder at a predetermined distance from the cylinder in a manner to cover the 90 DEG and 180 DEG gaps. The apparatus acting to modify the horizontal and vertical deflection magnetic fields so that the electron beam spots on the phosphor CRT screen are substantially circular in shape without losing the self convergence effect of the magnetic fields.