Patent ID: 7736290

Claim:
A sheet folding apparatus, comprising: a stacker configured to stack a plurality of sheets; a first folding roller configured to rotate around a first axis; a second folding roller configured to rotate around a second axis which is in parallel with the first axis and biased to the first folding roller separably to make a nip together with the first folding roller therebetween; a blade unit configured to push a surface of the plurality of sheets stacked by the stacker, into the nip; a first shaft configured to move together with the blade unit to support the blade unit; a second shaft configured to move together with the blade unit to support the blade unit; a first slot configured to support the first shaft and configured to guide linearly in a common tangential direction of the first folding roller and the second folding roller at the nip; and a second slot comprising a first distance section and a second distance section broader than the first distance section, configured to support the second shaft linearly movable along the common tangential direction in the first distance section when the blade unit passes an entrance section between where the blade unit starts touching at the plurality of sheets and where the plurality of sheets approaches the nip, and configured to deviate the second shaft away to the second folding roller side from a direction parallel to the common tangential line with blocking deviating the second shaft away to a first folding roller side from the direction parallel to the common tangential line in the second distance section when the plurality of sheets approaches the nip.