Abstract: A color picture tube comprises a tube envelope having a tube axis and including a neck section, a funnel section and a panel section, an electron gun assembly for emitting at least three electron beams, and a shadow mask assembly disposed in the tube envelope adjacent to the phosphor screen. The shadow mask assembly includes a shadow mask and a frame. The shadow mask has a plate portion which is formed having a curved surface with a dome-like shape opposing the phosphor screen and regularly arranged apertures each for allowing the three electron beams to pass through, and a skirt portion extending from the peripheral portion of the plate portion along the tube axis. The frame surrounds the peripheral portion of the skirt portion of the shadow mask, and the frame and the skirt portion of the shadow mask are coupled to each other by welding at a plurality of locations. The frame is made of a metal material having a thermal expansion coefficient higher than the shadow mask.

Abstract: The shadow mask of a color cathode ray tube has a number of apertures in the effective area passed by electron beams to the phosphor screen formed in the inner surface of the panel. The effective area where these apertures are distributed is in the nonspherical configuration adjacent to the phosphor screen surface. When taking the major axis as the X axis, the minor axis as the Y axis and the center of the shadow mask through where the tube axis (the Z axis) passes is made as a point of origin, the line of intersection defined by the plane containing the X axis and Z axis (X-Z plane) and the effective area is formed by the curve positioned as the panel side other than three points of which the circular arc passes in common through both terminal points and the center point on the above line of intersection, against the circular arc.

Abstract: In a color cathode ray tube with a shadow mask shaped as a nonspherical surface, a structure in which the curved surface shape of the effective area of the shadow mask in which apertures through which electron beams pass to a fluorescent screen are formed is made such that, going along the X axis, minimal values of radius of curvature of lines of intersection of the shadow mask and Y-Z parallel planes parallel to the minor axis Y and a central axis which passes through the mask's center and is normal to the mask exist between the center and the edges of the effective area. This prevents local doming.