Patent ID: 7521853

Claim:
A shadow mask for a cathode ray tube, the shadow mask being formed with a curved surface comprising a radius of curvature corresponding to a perpendicular axis which passes through the center of said shadow mask monotonely decreasing along the perpendicular axis from a center of said shadow mask and a radius of curvature corresponding to a parallel axis which passes through the center of the shadow mask monotonely decreasing along the parallel axis from the center of said shadow mask, the curved surface satisfying the following condition: [0.9RV min +0.1RV max , 0.1RV min +0.9RV max ]⊂[RH min , RH max ] wherein RV min and RV max respectively represent the minimum and the maximum value of the minimum radius of curvature corresponding to the perpendicular axis, and RH min and RH max respectively represent the minimum and the maximum value of the minimum radius of curvature corresponding to the parallel axis.