Patent ID: 7722030

Claim:
A sheet feeder comprising: a sheet tray which retains a sheet; at least one driving source; a first conveying mechanism comprising a first rotating body which is in contact with a sheet on the sheet tray and a first driving-force transfer mechanism which transfers a driving force of the driving source to the first rotating body; and a second conveying mechanism comprising a second rotating body which is in contact with the sheet on the sheet tray and a second driving-force transfer mechanism which transfers the driving force of the driving source to the second rotating body, wherein the second driving-force transfer mechanism comprises a one-way clutch configured to transfer the driving force of the driving source to the second rotating body under a predetermined condition; wherein the first rotating body is rotated in a conveying direction of the sheet by the driving force directly transferred by the first driving-force transfer mechanism and not transferred through the one-way clutch, so that the sheet positioned on the sheet tray is conveyed in a predetermined direction at a first speed; the second rotating body is rotated by a friction force between the sheet and the second rotating body and the driving force that is transferred through the one-way clutch is not transferred to the second rotating body, when a conveying speed of the sheet on the sheet tray is greater than a second speed which is smaller than the first speed; and the second rotating body is rotated in the conveying direction of the sheet by the driving force transferred by the one-way clutch of the second driving-force transfer mechanism, when the conveying speed of the sheet on the sheet tray is smaller than the second speed.