| 摘要 |
PURPOSE:To obtain a good quality shadow mask, by causing a rectangular cut out frame line on the opposite side of the flat mask of a rectangular frame to be a curved or straight smooth line. CONSTITUTION:A photosensitive film 22 is formed on both main surfaces of a rolled thin metal plate 21, and after two negatives, on which predetermined dots 23 and rectangular frame 24 are formed, are closely contacted on these photosensitve films 22 respectively, exposure process, development process, etching process, and photosensitive film removing process are carried out, and then electron-beam passing hole portions and a rectangular cut out frame line are formed on the metal plate 21 to obtain a flat mask. In this case, the envelope at the unevenness part 30 and the full line part 29 is a doubled line, and this doubled line part corresponding to the unevenness part 30, 31 is coated, for example, into black color so that the exposure light can not transmit therethrough. Thus, the rectangular cut out frame line on the metal plate 21 side is caused to be a curved or straight smooth line. |
