| 摘要 |
A shadow mask has a mask body and a substantially rectangular mask frame attached to a peripheral portion of the mask body. The mask body has a substantially rectangular curved effective surface opposed to a phosphor screen formed on an inner surface of a panel. The effective surface has a number of electron beam passage apertures. The effective surface of the mask body has a curvature in a direction of the long axis, which is set within a range of about 0 to 2x10-4 (1/mm) over an area from a center of the effective surface to a middle portion of the effective surface in the direction of the long axis. A curvature at a peripheral portion in the direction of the long axis is set to be greater than that at the middle portion. A curvature on the short axis in the direction of the short axis successively increases over a distance equal to at least two thirds of a distance between the center and an effective end of the short axis.
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