Patent ID: 7419156

Claim:
An overlapped-sheet detection apparatus, comprising: a forwarding roller rotating while making contact with sheets to forward the sheets; a shifting roller provided at a position where said shifting roller and said forwarding roller pinch at said sheets, said shifting roller being configured to shift said sheets if said sheets are overlapped and to follow a rotation of said forwarding roller if said sheets are not overlapped; driving torque means for supplying said shifting roller with driving torque to shift said sheets; detection means for detecting rotation states of said shifting roller; discrimination means for judging from said rotation states detected by said detection means that said sheets are overlapped; control means for controlling said driving torque means to transmit less driving torque than in ordinary cases when said discrimination means judges that said sheets are overlapped; and rear edge detection means for detecting a rear edge portion of said sheets when said sheets pass through a position where said forwarding roller is provided opposite to said shifting roller, wherein said control means controls said driving torque means to transmit less driving torque than in ordinary cases when said discrimination means judges that said sheets are overlapped and said driving torque means to return to transmission of driving torque in ordinary cases when said rear edge detection means detects the rear edge portion of said sheets.