A paper separation structure arranged in an office machine, comprising: a separating roller set having a separating roller and a shaft, and a pick roller arranged to correspond to the separating roller set and contacted with the separating roller set, wherein the separating roller has a roller frame, a shaft hole is formed in the roller frame for accommodating the shaft, and a rubber layer connected with the pick roller, the shaft hole has a narrow inner diameter at a middle of the shaft hole and a wide inner diameter at opposite ends of the shaft hole to form two swing spaces between the middle of the shaft hole and opposite ends of the shaft hole, the roller frame and the rubber layer are swung about a joint between the middle of the shaft hole and the shaft.

A sheet conveyor including a separation roller, a separation pad, an urging member urging the separation pad, and a feed roller unit disposed downstream relative to the separation roller in a conveyance direction, the feed roller unit including a first outer circumferential surface disposed on a first side in a width direction perpendicular to the conveyance direction, a second outer circumferential surface disposed on a second side opposite to the first side in the width direction, and a concave portion disposed between the first and second outer circumferential surfaces in the width direction, the concave portion being recessed inward in a radial direction of the first and second outer circumferential surfaces from the first and second outer circumferential surfaces, an urging member being disposed upstream relative to the concave portion in the conveyance direction and disposed between the first and second outer circumferential surfaces in the width direction.

A document conveying device includes a sheet feeding tray, a sheet feeding mechanism, a discharge tray, a sheet feeding tray lifting mechanism, a top plate, a fixed wall part, and a lifting wall part. The discharge tray is provided below the sheet feeding tray. The top plate is adjacent to the sheet feeding tray on a downstream side in the sheet feeding direction. The fixed wall part is provided extending downward from an upstream side end portion of the top plate in the sheet feeding direction, and is fixed. The lifting wall part is provided extending upward from a downstream side end portion of the sheet feeding tray in the sheet feeding direction, and lifted and lowered together with the sheet feeding tray. The discharge tray includes a lowering restriction part which comes into contact with the lifting wall part to restrict a lowering of the lifting wall part.

A transportation device transports a document sheet from a feeding tray to an output tray. A first lifting device lifts and lowers the feeding tray. A feeding-tray upperlimit sensor detects that the feeding tray reaches an upperlimit height. An output-tray sheet sensor detects the document sheet on the output tray. Further, the controller at a standby status (a) determines whether a document sheet is on the output tray or not, (b1) if a document sheet is not on the output tray, arranges the feeding tray at a predetermined intermediate position, and (b2) if a document sheet is on the output tray, arranges the feeding tray at a lower position that is a position apart by a predetermined distance from a position of the feeding tray when detecting that the feeding tray reaches the upperlimit height. Here, the lower position is a position higher than the intermediate position.

A document conveying device includes a sheet feeding tray, a sheet feeding mechanism, a sheet feeding tray lifting mechanism, a top plate, a fixed wall part, and a lifting wall part. The top plate is in contact with a lower surface of the document to be fed. The fixed wall part is provided extending downward from an upstream side end portion of the top plate, and fixed in position. The lifting wall part is provided extending upward from a downstream side end portion of the sheet feeding tray, and is lifted and lowered along the fixed wall part together with the sheet feeding tray. The lifting wall part has a slit along an upper-and-lower direction. The fixed wall part has a fin along the upper-and-lower direction. An upper end portion of the slit is opened in the upper-and-lower direction. The fin is arranged inside the slit.

A medium conveying apparatus includes a driving source to generate a driving force, a separation roller to separate a medium with the driving force, a mechanical clutch, and an applying part. The mechanical clutch includes a driving wheel rotated by the driving force from the driving source, and a driven wheel coupled to and uncoupled from the driving wheel by rotation of the driving wheel. The driven wheel coupled to the driving wheel transmits the driving force from the driving wheel to the separation roller. The applying part applies, to the driven wheel, a frictional force for restricting rotation of the driven wheel rotated by the driving wheel, and the frictional force applied by the applying part is greater than a frictional force between the driving wheel and the driven wheel.

A medium conveying apparatus includes a feed roller to feed a medium, a guide to restrict contact between the medium and the feed roller, a moving mechanism to move the guide, a driving source, and a drive transmission assembly to transmit a driving force for moving the guide from the driving source to the moving mechanism. The drive transmission assembly applies a load to the moving mechanism, and the load restricts transmission of force from the guide to the driving source.

A medium feeding apparatus includes a media tray, a feed roller to feed a medium placed on the media tray, a driving source to generate a driving force, and a drive transmission assembly to transmit the driving force from the driving source to a rotation shaft of the feed roller. The drive transmission assembly is located inner than an end of a medium conveying path in a direction intersecting a medium conveying direction.