| 摘要 |
PURPOSE:To prevent any deformation of a shadow mask by eliminating its residual strain stress by making the shadow mask to have a curved surface with a given ratio of a straight distance connecting the peripheral curved section of the main surface to a distance along the curved surface. CONSTITUTION:The shadow mask 5 of a shadow-mask-type color picture tube consists of a rectangular curved main surface 5a having many penetration holes and a curved skirt 8. Pressure formation for producing a uniform curved surface expansion rate is performed by obtaining a curvature radius R(theta) for each angle (theta) for a given ratio F(theta)/S(theta) when the shortest distance in a section cut by a segment (a-a') passing through the center (O) of the curved main surface 5a and at an angle (theta) relative to the vertical axis (Y) is supposed to be S(theta) and a distance along the curved surface is supposed to be F(theta). As a result, any deformation of the shadow mask 5 during its manufacture is prevented by performing very smooth formation, thereby achieving an improved color purity characteristic. |
