Abstract: To correct the beam direction, and thus the color purity of color television tubes, particularly in tubes having fixedly secured deflection systems (10), the deflection field is, upon adjustment for color purity, additionally modified by introducing a unidirectional magnetic field extending with its field lines parallel to the z-axis of the tube. After adjustment to move a predetermined color, for example red, from non-deflected or hardly deflected central beam positions into the center of the CRT, the d-c unidirectional field is then disconnected, and the apertured mask demagnetized, as conventional. For demagnetization, the already present demagnetization coil (9) on the tube may be used, by applying a constant voltage thereto, for example of 12 V. The decaying demagnetizing field can be derived from a transformer connected to network power (FIG. 2) or through an oscillatory circuit formed by a charge capacitor (17).

Abstract: A demagnetizing coil is situated in an aperture frame removably mounted around the picture screen of a picture tube.