JP2015054781A5 - Sheet processing apparatus and image forming apparatus - Google Patents

Description

The present invention relates to a sheet processing apparatus and an image forming apparatus that perform sheet skew correction before post processing such as punching.

The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to determine an appropriate correction amount for correcting the lateral displacement in consideration of the lateral displacement caused by the skew correction. An object of the present invention is to provide a sheet processing apparatus and an image forming apparatus .

Claims (8)

Conveying means for conveying the sheet;
Detecting means for detecting the side end position of the sheet in the width direction orthogonal to the conveying direction of the sheet by the conveying means while conveying the sheet;
Correction means for correcting the skew of the sheet by rotating the sheet around a predetermined position of the end in the conveyance direction of the sheet conveyed by the conveyance means;
First determination means for determining a skew amount of the sheet before skew correction by the correction means from a plurality of detection results of the detection means;
Second determining means for determining a displacement amount with respect to a prescribed lateral position of the sheet before skew correction by the correcting means from a detection result of the detecting means;
Prediction means for predicting a displacement amount in the width direction of the sheet caused by the skew correction by the correction means based on the skew amount determined by the first determination means;
Before the skew correction by the correction means, the correction amount for correcting the position of the sheet in the width direction is determined by the positional deviation amount determined by the second determination means and the displacement amount predicted by the prediction means. And a third deciding unit for deciding on the basis of the sheet processing apparatus. Wherein the correction means includes a contact member, said end portion of the sheet abuts the abutment member in the conveying direction, obliquely of the sheet by the sheet abutting position as the fulcrum is rotated The sheet processing apparatus according to claim 1, wherein line correction is performed. It said predicting means, the fulcrum and the distance to the lateral position of said defined in Na Ru position placed et the width direction, the skew amount of the determined of the sheet during skew correction of the sheet of the abutting member The sheet processing apparatus according to claim 2, wherein the amount of displacement is predicted based on:   The determination of the misregistration amount by the second determination unit, the prediction of the displacement amount by the prediction unit, and the determination of the correction amount by the third determination unit are all performed in the transport direction. The sheet processing apparatus according to claim 2, wherein the sheet processing apparatus is configured with respect to a position of an end portion that is in contact with the contact member.   The shift means for shifting the conveying means in the width direction based on the correction amount determined by the third determining means before the skew correction by the correcting means. 5. The sheet processing apparatus according to claim 1. A punching device for punching holes in the sheet;
Prior to skew correction by the correction means, based on the correction amount determined by the third determination means, the relative position in the width direction between the sheet conveyed by the conveyance means and the punching device is determined. The sheet processing apparatus according to claim 1, further comprising a shift unit that shifts the sheet.   The sheet processing apparatus according to claim 1, wherein the detection unit detects a side end position of the sheet in the width direction at a plurality of locations in the transport direction. Image forming means for forming an image on a sheet;
An image forming apparatus comprising: the sheet processing apparatus according to claim 1, wherein post-processing is performed on a sheet on which an image is formed by the image forming unit.