| 摘要 |
PURPOSE:To correct enlargement at press forming time, and enhance image quality by forming a dimension of a slot-shaped electron beam passing hole bored in an effective surface area of a shadow mask smaller than a central part in respective corner parts. CONSTITUTION:A large number of slots 53 are bored in an inside area of an effective surface boundary 51 of a partially fabricated shadow mask item 5' after etching work, and a part between the boundary 51 and a developing external shape 54 becomes a skirt part by press forming. Then, when a slot width of a slot 533 in the outermost row in the vertical scanning directiom Y-Y in a corner part in the horizontal scanning direction X-X is denoted by S3 and widths of slots 532 and 53'2 adjacent to each other in the X-X direction are denoted by S2 and S'2, S3<S2 and S3< S'2 or the like are realized. When the press forming is perfomed on the partially fabricated item 5', a dimesnion of the slot in the corner part is properly corrected, and landing tolerance of an electron beam is secured, and a high quality reproduction image can be obtained. |
