Abstract: In an improved method of etching apertures in a thin metal sheet to form a shadow mask for a color picture tube, the metal sheet has a first acid-resistant stencil on one major surface thereof and a second acid-resistant stencil on the other major surface thereof. At least one of the stencils has openings therein at locations of intended apertures. The improvement comprises the steps of magnetically holding the metal sheet with a flat magnetic assembly, and moving the magnetic assembly magnetically holding the metal sheet thereon through an etching chamber. The magnetic assembly includes a magnetic layer that is supported on an acid-resistant board.

Abstract: In an improved method of etching apertures in a thin metal sheet to form a shadow mask for a color picture tube, the metal sheet has a first acid-resistant stencil on one major surface thereof and a second acid-resistant stencil on the other major surface thereof. At least one of the stencils has openings therein at locations of intended apertures. The improvement comprises the steps of magnetically holding the metal sheet with a flat magnetic assembly, and moving the magnetic assembly magnetically holding the metal sheet thereon through an etching chamber. The magnetic assembly includes a magnetic layer that is supported on an acid-resistant board.

Abstract: In accordance with the present invention, a display apparatus 8 comprises a color CRT 10 having an evacuated envelope 11 with a faceplate panel 12 sealed to one end of a funnel 15 that is closed at the other end by a neck 14. The faceplate panel has a luminescent screen 22 on an interior surface thereof. A shadow mask 25 is located in proximity to the screen. The shadow mask comprises a metal sheet having a central portion and an exterior portion with a plurality of apertures 40, 43 therethrough. An electron gun 26 is disposed within the neck for generating and directing electron beams 28 toward the screen. A deflection yoke 30 is disposed around the envelope at the junction of the neck and the funnel. The yoke deflects the beams to scan a raster across the screen.

Abstract: An improved color picture tube includes a shadow mask and a dot screen, wherein the mask has two long sides and two short sides. The long sides of the mask parallel a central major axis of the mask, and the short sides parallel a central minor axis of the mask. The mask includes an array of apertures. The improvement comprises each of the shadow mask apertures being substantially rectangular with four sides. Two of the aperture sides approximately parallel the major axis and establish aperture height. The other two aperture sides approximately parallel the minor axis and establish aperture width The widths and heights of the apertures increase at a first rate and a second rate, respectively, from the center to the sides of the mask, along the major axis; and the widths and heights of the apertures increase at a third rate and a fourth rate, respectively, from the center to the top and bottom of the mask, along the minor axis.