Sheet feeder

A sheet feeder comprising:

• a transporter, adapted to transport a sheet in a transport direction;
• a separator roller and a break roller, disposed at a downstream side of the transporter in the transport direction, and forming a separating section in which the sheet is transported one by one;
• a first detector, operable to detect a rotation of the break roller;
• a second detector, operable to detect a leading end edge of the sheet at the separating section;
• a controller, operable to determine a state of the sheet with respect to the separating section based on the detected rotation of the break roller and the detected leading end edge of the sheet, and to control the break roller based on the state of the sheet.

A sheet feeder comprising:

• a transporter, adapted to transport a sheet in a transport direction;
• a separator roller and a break roller, disposed at a downstream side of the transporter in the transport direction, and forming a separating section in which the sheet is transported one by one;
• a first detector, operable to detect a rotational speed of the separator roller;
• a second detector, operable to detect displacement of the sheet at the separating section;
• a controller, operable to calculate:
• a feeding amount of the separator roller based on the rotational speed of the separator roller;
• and
• a slip ratio based on the feeding amount of the separator roller and the displacement of the sheet, and
• to control the break roller based on the slip ratio.