In a grid structure for a color picture tube of the type comprised of a pair of elongated frame elements disposed in substantially parallel, spaced apart relation at the top and bottom, respectively, of the grid structure, a pair of mechanically resilient brace members having mid-portions extending between the frame elements at the opposite sides of the grid structure and end portions affixed to the frame elements for maintaining the latter in their spaced apart relation, and a plurality of grid wires defining slits therebetween extending between the frame elements and being welded or otherwise affixed to the latter adjacent the opposite ends of the grid wires while the grid wires are longitudinally tensioned and the brace members are prestressed by forces acting on the frame elements in the directions to urge the frame elements toward each other; each brace member has a cross-sectional shape, such as, a rectangular shape, providing different section moduli in respect to correspondingly different axes passing through the centroid of the cross-sectional shape, and the mid-portion of each brace member is disposed so that an axis of the cross-sectional shape thereof which passes through the centroid at right angles to the axis about which there is a maximum section modulus is disposed in a plane containing the lines of action of the forces which act on the frame elements at predetermined points adjacent the respective end portions of the frame elements, for example, the points at which forces are applied to the frame elements for prestressing the brace members during the affixing of the grid wires to the frame elements.

In a color selective electrode of a cathode ray tube, a number of grid elements are stretched between a pair of arms of a frame, a damper wire is stretched on the grid elements by means of spring elements fixed to a pair of support members of the frame, and each spring element is provided with a locking means for temporarily positioning the damper wire, whereby the damper wire is fixed temporarily to the locking means during the forming of the fluorescent surface on the tube, and restored to a spaced, final position after forming the fluorescent surface.

A grid apparatus for use with a color cathode ray tube is described, having a pair of opposing frame members, and a pair of arm portions respectively welded at free ends thereof to the pair of opposing frame members for mechanically connecting the pair of opposing frame members, and for stretching the grid elements with a predetermined tension in cooperation with the pair of opposing frame members, in which each of the pair of arm portions is curved generally as a U-shape in substantially one plane. Both ends of the arm portions are respectively connected to the pair of opposing frame members at positions outside from their Bessel points, and the plane in which each of the pair of arm portions is arranged to respectively widened rearward with an angle from 45.degree. to 65.degree. with respect to a surface perpendicular to an axis of the grid apparatus.

A method of manufacturing, and the structure of an improved electron beam selection electrode of a color cathode ray tube having a pair of arm members with a plurality of grid elements attached thereto and extended therebetween, and a pair of supporting members for the pair of arm members. The method comprises the steps of arranging a damper wire of predetermined length between a pair of fixing members, covering each end of the damper wire arranged on each end of the pair of fixing members with a pair of thin film tapes, respectively, welding both of the damper wire and the thin film tapes thereon to each one end of the pair of fixing members to provide a damper assembly, arranging a wire portion of the damper assembly over a surface of the plurality of the grid elements, and fixing each of the other end of the pair of fixing members to each of the pair of supporting members so as to suppress mechanical vibration of the grid elements.

A mask assembly for a cathode ray tube includes a tension mask having an effective portion formed with strips spaced apart from each other forming slots there between and a non-effective portion surrounding the effective portion. A mask frame includes a pair of supporting members along long sides of the tension mask and a pair of elastic members spacing the supporting members from each other by a predetermined distance. Vibration damping members damp vibration of the tension mask, where the vibration damping members are tensioned in a longitudinal direction to pressurize the non-effective portion.