A document conveyance device includes a feed roller, a separation roller, a first motor for generating a first drive force for driving the separation roller, a planet gear, a drive gear, a second motor for generating a second drive force, and a position switching mechanism for switching a position of the planet gear from a first position in which the planet gear is separated from the drive gear and does not transmit the first drive force to the separation roller to a second position in which the planet gear engages with the drive gear and transmits the first drive force to the separation roller, based on the second drive force. The position switching mechanism includes a support member for supporting the planet gear, and a transfer mechanism for moving the support member so that the planet gear engages with the drive gear, based on the second drive force. The further movement of the planet gear is prevented after the planet gear engaged with the drive gear.

A medium conveying apparatus includes a feed roller, a brake roller, a motor to generate a driving force, a first transmission mechanism to transmit the driving force to the brake roller through a first torque limiter, to rotate the brake roller in a direction opposite to a medium feeding direction, a second transmission mechanism to transmit the driving force to the brake roller through a second torque limiter, bypassing the first torque limiter, to rotate the brake roller in the direction opposite to the medium feeding direction, and a processor to detect media multi-feed, and perform control in such a way as to transmit the driving force to the brake roller by the second transmission mechanism and also cause the feed roller to be driven to rotate in the direction opposite to the medium feeding direction by the brake roller, when the media multi-feed is detected.

A medium conveying apparatus includes a feed roller, a brake roller, a motor to generate a driving force, a first transmission mechanism to transmit the driving force to the brake roller through a first torque limiter, to rotate the brake roller in a direction opposite to a medium feeding direction, a second transmission mechanism to transmit the driving force to the brake roller through a second torque limiter, bypassing the first torque limiter, to rotate the brake roller in the direction opposite to the medium feeding direction, and a processor to detect media multi-feed, and perform control in such a way as to transmit the driving force to the brake roller by the second transmission mechanism and also cause the feed roller to be driven to rotate in the direction opposite to the medium feeding direction by the brake roller, when the media multi-feed is detected.

The sheet feeding apparatus includes an encoder configured to output a signal according to the rotation state of a retard roller, a feed motor configured to drive a pick-up roller, and a control unit configured to control the feed motor, make the pick-up roller feed a first sheet, and change the timing at which the pick-up roller is made to feed a second sheet following the first sheet, based on a signal output from the encoder after the trailing edge of the first sheet passes a separation nip portion.

The sheet feeding apparatus includes an encoder configured to output a signal according to the rotation state of a retard roller, a feed motor configured to drive a pick-up roller, and a control unit configured to control the feed motor, make the pick-up roller feed a first sheet, and change the timing at which the pick-up roller is made to feed a second sheet following the first sheet, based on a signal output from the encoder after the trailing edge of the first sheet passes a separation nip portion.

A medium transport apparatus includes: a feed unit feeds a medium to a transport direction; a first detection unit disposed upstream of the feed unit, and detects movement of the fed medium; a second detection unit disposed downstream of the first detection unit and detects an inclination of the medium; and a control unit detects the inclination of the medium based on a signal of the second detection unit and stop transfer of the medium when the inclination exceeds a threshold value, and the plurality of the threshold values have a relationship such that when a medium length in the transport direction is a second length being shorter than a first length, a relatively higher value is produced than in a case in which the medium length is the first length, and the control unit selects a threshold value based on a detection value of the first detection unit.

A medium transport apparatus includes: a feed unit feeds a medium to a transport direction; a first detection unit disposed upstream of the feed unit, and detects movement of the fed medium; a second detection unit disposed downstream of the first detection unit and detects an inclination of the medium; and a control unit detects the inclination of the medium based on a signal of the second detection unit and stop transfer of the medium when the inclination exceeds a threshold value, and the plurality of the threshold values have a relationship such that when a medium length in the transport direction is a second length being shorter than a first length, a relatively higher value is produced than in a case in which the medium length is the first length, and the control unit selects a threshold value based on a detection value of the first detection unit.

A feeding device includes a suction feeding unit having a belt for feeding a sheet in a suction state and a belt driving unit, a sheet detection sensor, and a control unit. The control unit controls the belt drive unit so as to feed the sheet in a feeding direction at a first speed. If the sheet does not arrive at the sheet detection sensor, the control unit controls the belt drive unit so as to execute a low-speed feeding of moving the belt in the feeding direction at a second speed lower than the first speed or so as to execute a reverse feeding of moving the belt in a reverse feeding direction opposite to the feeding direction.

A feeding device includes a suction feeding unit having a belt for feeding a sheet in a suction state and a belt driving unit, a sheet detection sensor, and a control unit. The control unit controls the belt drive unit so as to feed the sheet in a feeding direction at a first speed. If the sheet does not arrive at the sheet detection sensor, the control unit controls the belt drive unit so as to execute a low-speed feeding of moving the belt in the feeding direction at a second speed lower than the first speed or so as to execute a reverse feeding of moving the belt in a reverse feeding direction opposite to the feeding direction.

A conveyance mechanism capable of attaining high conveyance performance and protecting a conveyance object and a mechanism itself, a medium processing device and a conveyance method using the conveyance mechanism are provided to solve the problem. The conveyance mechanism includes a conveyance passage which is a passage where a conveyance object is conveyed, a conveyance member moving the conveyance object along the conveyance passage, a motor driving the conveyance member, a control part controlling an output torque of the motor, a conveyance state identifying means identifying a conveyance state that is a position and/or a conveyance direction of the conveyance object in the conveyance passage, and a storage part which upper limit torque information which is an upper limit value of an output torque allowable for the motor or a parameter value required for calculation of the upper limit value is registered for each type of the conveyance state.