Colour display tube provided with a colour selection electrode

Abstract

In the manufacturing process of a color display tube (1), the display window (3) is assembled with the funnel shaped part (4) in a furnace by subjecting them to a heat treatment. This heat treatment can lead to deformation of the color selection electrode (12), because in color display tubes (1) with an invar shadow mask (13), the diaphragm parts (15) are made from invar as well, while the corner sections (16) are made from iron in order to obtain enough stiffness. The difference in expansion coefficient between invar and iron leads to shearing of the welds (22) that connect the diaphragm parts (15) to the corner section (16). To overcome this problem the invention proposes to provide the diaphragm parts (15) with slits (23) or impressions (24), which are arranged so that no stress occurs between the spot welds (22) when the color selection electrode (12) is heated.

Dependencies are inferred from the claim text.