| 摘要 |
PROBLEM TO BE SOLVED: To maintain a hole shape even if the material of a shadow mask is a thin plate, conduct sufficient plastic work at the same time, and obtain sufficient strength against the outside shock by compression the hole formed part of a shadow mask in the plate thickness direction and forming a plurality of recesses. SOLUTION: A flat mask in which many electron beam passing through holes 18 are formed is press-molded to obtain a shadow mask 6 having a predetermined shape. The inner surface of the hole formed part 20 of the shadow mask 6, or a recesses surface is compressed with a impact force applying device in the plate thickness direction, and a plurality of recesses 22 having a depth of 10-40μm are formed. The recess 22 formed by compression is a dented and hardened impression, and increases mechanical strength of the shadow mask 6. Even if the material of the shadow mask 6 is a thin plate, the strength of the shadow mask 6 is increased without damaging the shape of the electron beam passing through hole 18.
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