Patent ID: 8636275

Claim:
An automatic document feeder comprising: a separating and feeding unit which has a separating member and a paper feeding member configured to contact the separating member at a predetermined separating pressure, the separating member and feeding member cooperating to separate and feed originals one-by-one from a bundle of originals placed on an original placing table; a conveyor configured to convey the originals separated by the separating and feeding unit toward a scanning position; a separating pressure switch configured to allow the separating pressure to be applied and released; a first detector between the separating and feeding unit and conveyor, the first detector configured to detect the originals conveyed from the separating and feeding unit to the conveyor; and a controller configured to control the separating pressure switch to release the separating pressure after a leading edge of a first original has passed through the separating and feeding unit and to apply the separating pressure before a second original is fed from the bundle of originals to the separating and feeding unit; a second detector, which is provided between the separating and feeding unit and the conveyor, wherein, when a trailing edge of the first original is detected by the second detector, the controller controls the separating pressure switch to allow the paper feeding member to apply pressure to the separating member; a third detector, provided on a downstream side in an original conveying direction of the conveyor, to detect one or more of the originals including the second original conveyed by the conveyor, wherein: the first original precedes the second original, after a leading edge of the first original is detected by the first detector, the controller controls the separating pressure switch to allow the first original to be conveyed by an additional distance farther than a distance between the first detector and the conveyor, and after a leading edge of the second original is detected by the third detector, the controller controls the separating pressure switch to allow the paper feeding member to apply pressure to the separating member.