Patent ID: 8752820

Claim:
An envelope warpage correcting device comprising: a sheet feeding portion that feeds envelopes one-by-one using a sheet feed roller, the sheet feed roller configured to retrieve an envelope from a stack of envelopes that are stacked on a sheet feed table, wherein the envelopes comprise a first end portion that is opposite a flap portion, and the envelopes are arranged in a sheet feed direction, with the first end portion nearest the sheet feed roller; a correcting portion that is arranged in a downstream direction with respect to the sheet feeding portion and configured to correct warpage occurring at a side of the first end portion of the envelope fed by the sheet feeding portion, wherein the correcting portion includes a correction roller and a pressing mechanism configured to apply a first pressure to an envelope via the correction roller; and a control portion that is configured to control the correcting portion to apply the first pressure to the envelope, and reduce the pressing force to the envelope to which the first pressure has been applied resulting in a second pressure that is less than the first pressure at a certain timing according to an attribution of the envelope, wherein the control portion controls the pressing mechanism at the certain timing to reduce the pressing force of the correction roller to the envelope resulting in the second pressure according to the attribution of the envelope.