Deflection unit for a three-beam colour television tube

摘要

In the case of known colour television tubes, the two side beams (red, blue) are distorted, especially at the top and bottom of the screen, as a result of the barrel-shaped nature of the vertical deflection field of the vertical deflection coil. This distortion can be compensated for by designing the deflection field in the shape of a cushion at the level of the small winding overhang. The rotation given to an edge beam in the region of the small winding overhang of the deflection unit is then opposite to that rotation which this edge beam is given in the region of the large winding overhang of the deflection unit, so that this edge beam is no longer rotated, that is to say distorted, after passing through the complete magnetic deflection field. The cushion shape in the region of the small winding overhang is produced by suitable field formers, for example by pole elements (PS) which end in a fork shape, and vertical shunts (VS) which can be combined therewith. The invention can be used, for example, in the case of 90 DEG colour television tubes which operate using toroidal deflection coils in the vertical deflection unit. <IMAGE>