| 摘要 |
PURPOSE:To reduce the beam landing error resulting from a thermal expansion of the shadow mask, by composing a shadow mask applied with a tension and a mask frame to hold the shadow mask by combining low thermal expansion materials. CONSTITUTION:A tension imposed to a shadow mask 22, a mask frame 23, an extension 24, and frame supporters 25 are composed by combining low thermal expansion materials respectively. Metallic materials for the shadow mask 22 and for the mask frame 23 are both a metal having a winding point of the thermal expansion curve below 500 deg.C, and a material of a lower temperature winding point is used for the shadow mask 22 while that of a higher temperature winding point for the mask frame 23. Since the mask frame 23 keeps its balance in the condition bending inward as shown in the broken line 23', the tension of the shadow mask 22 is relaxed by moving in the direction of the arrow 29 when the shadow mask 22 is expanded by heating.
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