Patent ID: 8126386

Claim:
A sheet feeder comprising: a sheet feed roller to covey a sheet provided at a position of the upstream side of an aligning roller along the sheet conveying direction; the aligning roller starts to rotate when a sheet is conveyed; a clutch to transmit and cut off the driving force from a driving source to rotate the feed roller; a rotary shaft connected to the clutch in the rotatable state; an inertial member provided to the rotary shaft; and a torque limiter comprising an inner ring fixed to the rotary shaft and an outer ring fixed to the inertia member, the clutch having further a function to disengage after transmitting the driving force from the driving source to the inertial member by engaging first at the time when feeding sheets and to make a second engagement successively, and a controller that controls the engagement of the clutch at a time T 1 , when the driving force is transmitted to the rotary shaft causing the sheet feed roller to rotate, disengagement of the clutch at a time T 2 , when the driving force is transmitted to the inertial member at specified time after the aligning roller is turned on causing specified flexion on the sheet, and the second engagement of the clutch at a time T 4 , while the inertial member is continuously rotating.