Patent ID: 8385762

Claim:
A transfer device comprising: a plurality of supporting members; an image carrying belt that is stretched around the supporting members in a loop-like manner and that makes an endless movement; a transfer roller that is disposed opposite to one of the supporting members across the image carrying belt and that abuts against an outer surface of the image carrying belt to form a transfer nip; a driving source that drives a driving roller that is one of the supporting members other than the one of the supporting members opposite to the transfer roller across the image carrying belt; a driving force transmission unit that transmits a driving force from the driving source to the driving roller; a drive control unit that performs drive control of the driving source; a feedforward control unit that performs a feedforward control on the driving source via the drive control unit to reduce speed variance in the endless movement of the image carrying belt caused due to an entry of a sheet in the transfer nip; and an entry detecting unit that detects an entry of a sheet in the transfer nip and outputs an entry detection signal, wherein the transfer device transfers a visible image that has been formed on a surface of a latent-image carrying member on the outer surface of the image carrying belt and then transfers the visible image that has been transferred on the outer surface of the image carrying member on the sheet that has entered the transfer nip, and the feedforward control unit considers the entry detection signal output by the entry sensor as a trigger for performing feedforward control after a predetermined time, and wherein the one of the supporting members opposite to the transfer roller across the image carrying belt is a supporting roller, and the entry detecting unit includes a rotation information obtaining unit that obtains rotation information regarding a rotating state of the supporting roller, the rotating state undergoing variance by an entry of a sheet in the transfer nip; and an entry sensor that detects the entry of the sheet in the transfer nip by using the rotation information obtained by the rotation information obtaining unit and outputs an entry detection signal.