| 摘要 |
In a bag-making macine where a base is formed on an end of a tube section by folding and successively folded tube sections are conveyed transversely at intervals with the main part of each tube section flattened and its folded base perpendicular thereto, photocells are provided to scan the leading and trailing folded edges of each base. The photocells and a light source are disposed on opposite sides of each base and an arcuate disc rotatable about its center of curvature at a circumferential speed equal to the conveying speed of the tube sections bridges the intervals between the bases of successive tube sections so that the photocells remain unexposed unless the bases are deformed.
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