Horizontal convergence circuit

TLDR: In this paper, a horizontal convergence circuit for a color television receiver has at least first and second coils for magnetically converging a plurality of electron beams in a cathode-ray tube.

Abstract: A horizontal convergence circuit for a color television receiver having at least first and second coils for magnetically converging a plurality of electron beams in a cathode-ray tube. The convergence circuit has a transformer which is coupled intermediate the two coils. This convergence transformer is coupled to the flyback transformer and is energized therefrom at the horizontal deflection rate. The two convergence coils are coupled in series with the secondary of the convergence transformer and have their polarities arranged in such a way so that the transformer produces series adding voltages across the coils. The convergence transformer has a movable core which allows the transformer to be adjusted to control the spacing between vertical test lines on the screen of the cathode-ray tube. A resistor is connected in parallel with the convergence coils and a variable tap on the resistor is coupled directly to a center tap on the secondary of the convergence transformer. This arrangement provides a differential amplitude control for the parabolic current in the coils. Further parallel connected resistors provide a differential tilt control and a master tilt control for the coils. The differential tilt control regulates the proportion of sawtooth current delivered to each coil, while the master tilt control regulates the amount of sawtooth delivered to both coils simultaneously. A single diode is coupled across both the coils and restores DC to allow the center of the parabola to be fixed at a given DC reference.