COLOUR DISPLAY TUBE WITH WEAKENED PORTION IN SHADOW MASK

摘要

PHN 10. 78 7.9.1982 "Colou display tube". A mask sheet (8) which has a pattern of elongate apertures (10) is deep-drawn by means of a bilateral drawing process in which the edge (9) is bent over along the folding line (21). In the corner of the skirt (23) a pattern of pits (24) is provided the longitudinal direction of which is parallel to the diagonal (25) of the mask sheet (8). As a result of the pits (24) the skirt (23) is weaker in a direction at right angles to the diagonal (25) than in a direction parallel to the diagonal (25). The pits (24) compensate the buckle load occurring in the bilateral drawing process and are deformed at right angles to the longitudinal direction. As a result of this the formation of pleats in the corners of the mask sheet (8) is prevented.