A medium conveying apparatus includes a driving force transmitting mechanism to transmit a driving force from a first motor to a brake roller and a pair of conveyance rollers located on the downstream side of the brake roller, and a processor to rotate the first motor forward to control so that a medium separated by the brake roller is conveyed by the pair of conveyance rollers, in a separation mode. The processor rotates the first motor backward to perform a feed operation by the brake roller and rotate the pair of conveyance rollers backward until a front edge of the medium passes through a position of the brake roller, and rotates the first motor forward to control so that the medium is conveyed by the pair of conveyance rollers after the front edge of the medium passes through the position of the brake roller, in a non-separation mode.

A transport device includes a transport roller, a nip section, and first and second transport path surfaces. The transport roller transports a transport target material sent from an accommodating unit. The nip section nips the transport target material with the transport roller, and prevents multi-feed of the transport target material. The first transport path surface is disposed upstream of the nip section in a transport direction to face a transport roller side of the nip section. The first transport path surface includes a top portion protruding toward the transport roller side beyond a nip line between the transport roller and the nip section. The second transport path surface is disposed downstream of the nip section in the transport direction to face the transport roller side of the nip section. The second transport path surface includes a top portion protruding toward the transport roller side beyond the nip line.

The document feeder includes a lift plate, a pickup roller, a lift motor, a retard roller, and a control unit. In a manual feed mode, the control unit rotates the retard roller to feed a document in a document conveyance direction. Further, the control unit causes the lift motor to start lowering the lift plate while the pickup roller is feeding a document after starting to rotate the pickup roller. When there is a document set on the lift plate at the time when the pickup roller stops, the control unit automatically resumes the feeding in the manual feed mode.

A printing medium feeding device includes a loading unit into which a printing medium is loaded, a pickup roller which picks up the loaded printing medium, a retard roller, a forward roller engaged with the retard roller to feed the picked-up printing medium in a first direction, a torque limiter to apply torque in a second direction opposite to the first direction to the retard roller, and a processor. The processor controls driving of the forward roller by generating a pre-driving signal to change a torque state of the torque limiter to an effective torque state for preventing multi-feeding of printing media and controls driving of the forward roller by generating a driving signal to feed the printing medium in the first direction.

A scanner includes a reading unit that reads an image of a paper, a medium feeding portion that is capable of selecting a first feeding mode in which a separation feeding for separately feeding a paper bundle in which a plurality of sheets of paper is overlapped with each other is performed and a second feeding mode in which a non-separation feeding for collectively feeding the paper bundle without separating is performed, and a pair of first transporting rollers and a pair of second transporting rollers that transport the paper fed by the medium feeding portion, in a case in which the medium feeding portion feeds the paper in the second feeding mode, a first driven roller and a second driven roller respectively constituting the pair of first transporting rollers and the pair of second transporting rollers are driven in a rotation direction where the paper is transported.

A scanner includes a reading unit that reads an image of a paper, a medium feeding portion that is capable of selecting a first feeding mode in which a separation feeding for separately feeding a paper bundle in which a plurality of sheets of paper is overlapped with each other is performed and a second feeding mode in which a non-separation feeding for collectively feeding the paper bundle without separating is performed, and a pair of first transporting rollers and a pair of second transporting rollers that transport the paper fed by the medium feeding portion, in a case in which the medium feeding portion feeds the paper in the second feeding mode, a first driven roller and a second driven roller respectively constituting the pair of first transporting rollers and the pair of second transporting rollers are driven in a rotation direction where the paper is transported.

Provided are: a sheet feed device that is capable of suppressing the occurrence of a sheet feeding fault by changing the pressing contact force of a retard roller against a feed roller; and an image formation device equipped with the same. This sheet feed unit (50) is provided with: a pickup roller (29); a feed roller (31); a retard roller (32); a holding member (40) that holds the retard roller (32); a first biasing member (42) that biases the holding member (40); and a pressing contact force changing mechanism (60) that changes the pressing contact force of the retard roller (32) against the feed roller (31). The pressing contact force changing mechanism (60) has: a rotary shaft (61) disposed parallel to the axial direction of the retard roller (32); a cam member (70) that rotates with the rotary shaft (61); and a movable member (80) that contacts the cam member (70), moves in the axial direction in conjunction with the rotation of the cam member (70), and changes the biasing force generated by the first biasing member (42).

Provided are: a sheet feed device that is capable of suppressing the occurrence of a sheet feeding fault by changing the pressing contact force of a retard roller against a feed roller; and an image formation device equipped with the same. This sheet feed unit (50) is provided with: a pickup roller (29); a feed roller (31); a retard roller (32); a holding member (40) that holds the retard roller (32); a first biasing member (42) that biases the holding member (40); and a pressing contact force changing mechanism (60) that changes the pressing contact force of the retard roller (32) against the feed roller (31). The pressing contact force changing mechanism (60) has: a rotary shaft (61) disposed parallel to the axial direction of the retard roller (32); a cam member (70) that rotates with the rotary shaft (61); and a movable member (80) that contacts the cam member (70), moves in the axial direction in conjunction with the rotation of the cam member (70), and changes the biasing force generated by the first biasing member (42).

A sheet feed device includes a pair of sheet feed rollers, a pair of separation pads, and a first contact portion. The pair of sheet feed rollers are provided in alignment with an interval between them in a width direction perpendicular to a feeding direction in which sheets placed on a sheet placing portion are fed, and feed a sheet from the sheet placing portion. When an overlapping sheet overlaps under a target sheet that is in contact with the pair of sheet feed rollers, the pair of separation pads separate the overlapping sheet from the target sheet. The first contact portion is provided on the holder at a position between the pair of separation pads and projecting more than contact surfaces of the pair of separation pads, and comes in contact with the lower surface of the sheet.

A document feeder constituting an image forming apparatus includes a paper feeder to supply a document to a document transport path, a first transporter to transport the document toward image reading positions, and a second transporter to transport the document toward the document discharging tray while supplying the document to the image reading positions. Furthermore, the document feeder includes a motor provided on the first frame, a first driver provided on the first frame and to transmit driving force generated by the motor to the paper feeder and the first transporter, a second driver provided on the second frame and to transmit the driving force generated by the motor to the second transporter, and a second driver to transmit the driving force generated by the motor to the second transporter, and a relay transmission member to transmit the driving force generated by the motor to the second driver.