Colour TV CRT with coma correcting circuit - has two plates inducing weakening of outer vertical deflection field and opposite plates for horizontal field

摘要

The coma effect correcting circuit is used in a colour TV tube. The coma effect is caused by the faulty convergence in the horizontal and vertical direction due to ferromagnetic plates close to the bottom of the cup shaped fort grid electrode of the electron gun. There are two plates (A, B) which will induce a weakening effect of the vertical deflection field of the two outer beams. Their relative intensifiers of the same field w.r.t. the centre beam. The plates will be simultaneously relative weakeners or intensifiers for all three beams in the horizontal deflection field. The plates have rectangular centre sections (3, 4) with a pair of wing sections (2, 5, 1, 6) at an angle relative to the Y axis.