| 摘要 |
PURPOSE: A structure of a shadow mask of a color cathode ray tube is provided to improve a flat characteristic of a screen by changing a shape of a valid face in a shadow mask having an arbitrary curvature. CONSTITUTION: A curvature of a curved surface of a shadow mask has a vertical axis of -10mm, a horizontal axis of -12mm, and a diagonal axis of -20.7. In the curvature of an opening portion column of a flat mask for fabricating the shadow mask having the curved surface, a CC line as the outer opening portion column is formed in a straight line from the horizontal axis to 110 or 130mm. The CC line has the curvature which is curved to an inner direction beyond 110 to 130mm from the horizontal axis. The double curvature of the CC line is obtained by Xcc=251.5854-8.79778E-03x Y+1.635261E-04xY¬2-8.281584E-07xY¬3.
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