Patent ID: 9244395
Filing Date: 2016-01-26
CPC Classification: B65H,G03G

Claim Text:
1. An image forming apparatus comprising: a transfer unit configured to transfer a toner image onto a sheet; a fixing unit configured to fix the toner image transferred onto the sheet by the transfer unit; a sheet conveyance path disposed between the transfer unit and the fixing unit; a first detection unit configured to generate a signal according to a loop of the sheet at a central portion in a width direction orthogonal to a sheet conveyance direction of the sheet conveyance path; a second detection unit configured to generate a signal according to a loop of the sheet on one side of the sheet in the width direction of the sheet conveyance path; a third detection unit configured to generate a signal according to a loop of the sheet on another side of the sheet in the width direction of the sheet conveyance path; and a control unit configured to control a sheet conveyance speed at the fixing unit based on signals from the first detection unit, the second detection unit, and the third detection unit, wherein the control unit switches the sheet conveyance speed at the fixing unit to either a first sheet conveyance speed or a second sheet conveyance speed that is faster than the first sheet conveyance speed based on a signal from the first detection unit in a case where the control unit detects that both a loop amount of a loop of the sheet at a detection position of the second detection unit and a loop amount of a loop of the sheet at a detection position of the third detection unit are greater than a predetermined amount, or in a case where the control unit detects that both the loop amount of the loop of the sheet at the detection position of the second detection unit and the loop amount of the loop of the sheet at the detection position of the third detection unit are less than the predetermined amount, based on the signals from the second detection unit and the third detection unit, and wherein the control unit sets the sheet conveyance speed at the fixing unit as a predetermined sheet conveyance speed between the first sheet conveyance speed and the second sheet conveyance speed in a case where the control unit detects that one of the loop amounts of the sheet at detection positions of the second detection unit and the third detection unit is greater than the predetermined amount based on the signal from the one of the second detection unit and the third detection unit when the other of the loop amounts of the sheet at detection positions of the second detection unit and the third detection unit is less than the predetermined amount based on the signal from the another one of the second detection unit and the third detection unit.