Patent ID: 8424869

Claim:
An automatic document feeder comprising: an original scanning section to scan a face of an original sheet of paper; a first transportation path provided at one side of a scanning position of the original scanning section to guide the original to the scanning position of the original scanning section so that a first face of the original can be scanned; a looped second transportation path provided at the other side of the scanning position to guide the original to the scanning position so that a second face of the document can be scanned; a first roller portion provided on the first transportation path to feed the original to the scanning position so that the first face of the original can be scanned; a second roller portion provided on the looped second transportation path to transport the original that has been sent out from the first roller portion and scanned at the scanning position along the looped second transportation path; a third roller portion provided on the looped second transportation path to feed the original to the scanning section so that the second face of the original can be scanned; a fourth roller portion provided on the first transportation path to transport the original that has been sent out from the third roller portion and scanned at the scanning section; an original transportation control section that controls to transport the original from the first transportation path to the looped second transportation path with the first roller portion and the second roller portion when the first face of the original is scanned and to transport the original from the looped second transportation path to the first transportation path with the third roller portion and the fourth roller portion when the second face of the original is scanned; and a transporting speed adjusting unit that controls a circumferential velocity of the second roller portion to be faster than the one of the first roller portion when the original is transported from the first transportation path through the scanning position to the looped second transportation path, and also controls a circumferential velocity of the fourth roller portion to be faster than the one of the third roller portion when the original is transported from the looped second transportation path through the scanning position to the first transportation path.