Colour television display apparatus incorporating a television display tube

摘要

Colour television display apparatus provided with a display tube in which the electron beams are generated in one plane. The deflection coils are designed in such known manner that the landing points of the beams on the display screen coincide. Owing to tolerance angular errors of the orientation of the plane relative to one direction of deflection convergence errors are produced in the other direction of deflection. They are corrected by means of a magnetic quadripolar field the polar axes of which substantially coincide with the directions of deflection and the field strength of which is a substantially quadratic function of either deflection current or the sum of both functions.