Flat mask for cathode ray tube

This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from my application FLAT MASK AND METHOD FOR ASSEMBLING THEREOF, AND TENSION MASK ASSEMBLY MADE IN ACCORDANCE WITH THIS METHOD filed with the Korean Industrial Property Office on May 8, 2001 and there duly assigned Ser. No.0024972/2001. The present invention describes the details of a flat mask before tension is applied, an assembling method of that flat mask, and a tension mask assembly manufactured by using that method in order to obtain satisfactory thermal expansion, uniform stress distribution and linearity. The flat mask includes an apertured portion and supporting ends surrounding the apertured portion. The apertured portion comprises a plurality of concave pin-cushion type or convex barrel type strips, a plurality of real bridges connecting strips and dividing slots, and dummy bridges formed in the slots. The short supporting ends have the same width along a longitudinal direction and are formed to have the same curvature as the strips facing the supporting ends. The short supporting ends are preferably half-etched in order to make the volume of material removed from the short supporting ends greater than the volume of material removed from the apertured portion. Therefore, the short supporting ends can have grooves on their front and rear sides. In addition, the corner portions of the supporting ends are made to have sloping sides at a predetermined angle. As a result of manufacturing the tension mask by using the method of the present invention, the apertured portions of the tension mask have satisfactory thermal expansion, uniform stress distribution and linearity. In addition, it is possible for the tension mask to be prevented from having deformation caused by heat treatment after being held under tension.