Deflection yoke with a core extension

摘要

A deflection yoke includes a first core portion and a core extension portion. The core extension portion is located in the rear of the yoke closer to the beam entrance region. To adjust the yoke for the particular cathode ray tube on which it is mounted, the position of the yoke is adjusted for obtaining acceptable image geometry. Then, the core extension is moved with respect to the first core portion in a direction perpendicular to the longitudinal axis of the tube to obtain convergence symmetry while the position of the first core portion remains the same. In this way, convergence symmetry adjustment is accomplished separately from image geometry adjustment.