Deflection yoke incorporating a permeable corrector

Abstract

In a color television display system comprising a kinescope having in-line electron beams and a deflection yoke having saddle horizontal and toroidal vertical windings, a correcting apparatus comprises a magnetically permeable ring disposed at the rear of the yoke around the neck of the kinescope. Slots are formed into the ring at the top and bottom, separating it into two semi-circular segments. External flux from the deflection yoke horizontal and vertical coils is shunted into the permeable corrector and away from the focus region of the kinescope electron gun assembly, thereby improving beam focus and reducing vertical coma error. The slots formed in the ring prevent excessive flux from being shunted into the corrector which otherwise would undesirably reduce the amount of beam scan, and require a compensating increase in deflection power.