| 摘要 |
PURPOSE:To prevent deterioration of color purity due to welding by limiting the welding point with the shadowmask frame within two for one short side and two diagonal sections. CONSTITUTION:The shadowmask bodies 7-9 is made of low thermal expansion metal while the frame is made of common iron material where the shadowmask is welded to the inside of frame at three points on the long side while two points on the short side. Upon function of color picture tube, the frame will thermally expand to apply tensile force in the arrow direction through the welded points thus to vary the landing position of electron beam onto the fluorescent material, but since the welding points on short side and diagonal section is limited, outward tensile force of the shadowmask near the horizontal axis is weakened. Consequently, the difference of the variation of landing position of electron beam in horizontal direction near the horizontal axis and the diagonal axis is reduced resulting in cancellation of the deterioration of the color purality.
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