| 摘要 |
PURPOSE:To keep off any break in a shadow mask due to stress concentration in time of metalforming by a press, by making an external line adjoining a nonhalf-etching domain for spot welding to a half-etching domain into nonparallelism with the external line of the shadow mask itself. CONSTITUTION:A shadow mask used for a color picture tube is provided with a hole where an electron beam passes in its central part, and a metallic thin plate subjected to halfetching 2 as a whole is formed by a press with nonhalf-etching domains 3a and 3b for spot welding installed in a peripheral part left behind. The domains 3a and 3b are constituted by only such a part that an external line adjoining to the half-etching domain 2 is nonparallelism with the external line of the shadow mask itself, and therefore it is formed so as to have no parallel part. Accordingly, in time of metalforming by the press, any stress concentration is not produced in a specific part, permitting of dispersing the stress, thus any break in the shadow mask is preventable. |
