Colour CRT system having reduced horizontal spot growth - has magnetic field generator between gun and deflection unit to induce under-convergence of two outer electron beams

摘要

The element (14) which causes underconvergence is disposed between the beam-forming part of the electron gun and the deflection unit. The element exerts, on each outer electron beam, a force having a component in the plane of the electron beams directed transversely to the axis of the respective outer beam (20,22) and remote from the central electron beam (21). The deflection unit is constructed so as to generate deflection fields causing overconvergence which compensates the underconvergence of the element (14). The element has a magnetisable annular core (15) and four coils (16-19) arranged to form a four-pole magnetic field.