Patent ID: 8752828
Filing Date: 2014-06-17
Classification: B41J,B65H,G03G

Abstract:
1. An image forming apparatus, comprising: an image forming unit for forming an image on a sheet; a sheet feeding unit for feeding the sheet; at least one detection member provided on an upstream side of the image forming unit in a sheet transportation direction; a registration roller for transporting the sheet fed from the sheet feeding unit toward the image forming unit, the registration roller being configured to be held in a stopped state when the at least one detection member provided on the upstream side in the sheet transportation direction detects sheet arrival, and to rotate when a predetermined waiting time period has elapsed since the at least one detection member provided on the upstream side detects the sheet arrival; a rotational member for transporting the sheet fed from the sheet feeding unit toward the registration roller, the rotational member being configured to continue rotation until transportation of all the sheets to be used for printing is completed; and a sheet size detection unit for detecting a size of the sheet in response to an output from the at least one detection member using a time period from a time when the at least one detection member detects the sheet arrival to a time when the at least one detection member detects sheet passage; wherein the at least one detection member comprises: an upstream detection member provided on an upstream side of the registration roller in the sheet transportation direction; and a downstream detection member provided on a downstream side of the registration roller in the sheet transportation direction, and wherein the sheet size detection unit detects the size of the sheet using a first measurement time period from sheet arrival detection of the upstream detection member to sheet passage detection of the downstream detection member.