| 摘要 |
PROBLEM TO BE SOLVED: To provide sheet folding rollers, preventing the wrinkling of sheets, simplifying necessary sensors and control, and easy in manufacturing. SOLUTION: The two opposed sheet folding rollers 42 between which a two-folded sheet is held to be creased, each having an outer diameter gradually smaller in two or three stages as tending from an axial center portion toward both outsides. With the outer diameter uneven in three stages, the outer diameters of a center region W1 accounting for 15% or more to less than 40% of a total sheet passage region W at the axial center portion, both end regions W3 accounting for 35-60% at both axial ends and an intermediate region W2 accounting for the remaining region are different from one another, and the outer diameters at both sides are symmetrical to the outer diameter at the center portion in the axial direction. The percentages of the outer diameters of both end regions W3 and the intermediate region W2 to the outer diameter of the center region W1 are 95-98% and 98-99%, respectively. COPYRIGHT: (C)2004,JPO
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