Patent ID: 7690650

Claim:
A sheet transporting device comprising: a sheet feeding section that feeds plural sheets one by one to a transporting path; a pair of upstream transporting rollers and a pair of downstream transporting rollers that are arranged at the upstream side and the downstream side of the transporting path with a predetermined space, and are driven for transporting sheets; a double feed detecting section that detects a length of a double feed portion, which is an overlapped portion, of sheets fed in such a manner that another sheet is overlapped with a part of one sheet; a determining section that determines the length of the double feed portion is shorter than the predetermined space or not; and a transport control section that controls the drives of the pair of the upstream transporting rollers and the pair of the downstream transporting rollers, wherein the transport control section controls the transporting speeds of the pair of the upstream transporting rollers and the pair of the downstream transporting rollers to separate the delaying sheet from the preceding sheet of the overlapped sheets determined by the determining section to have a length of the double feed portion shorter than the predetermined space, while the double feed portion is positioned between the pair of the upstream transporting rollers and the pair of the downstream transporting rollers, and the transport control section controls each of the pairs of the transporting rollers so as to return both the preceding sheet and the delaying sheet to the sheet feeding section and further controls the sheet feeding section so as to re-feed the returned sheets in a case where the length of the double feed portion is not less than the predetermined space.