A sheet conveyance device includes a frame, first and second rollers, a roller shaft, an urging member, and a bearing. The bearing includes a holding portion to slidably hold the roller shaft and held by the frame. The holding portion is deformable. As viewed in a rotational axis direction of the roller shaft, a direction in which the urging member urges the second roller is defined as a first direction, a direction that is perpendicular to the first direction is defined as a second direction, and a region where the roller shaft is present in the second direction is defined as a first region. The frame holds the bearing so as not to be in contact with the holding portion in the first region downstream of a rotation center of the roller shaft in the first direction.

A rotatable-member-supporting structure includes a first rotatable member having a shaft portion, a bearing member by which the shaft portion of the first rotatable member is rotatably supported, a pressing member that presses the bearing member in one direction, and a supporting member by which the bearing member is supported in such a manner as to be retractably movable in the direction in which the pressing member presses the bearing member. A pressing force generated by the pressing member is greatest in a portion of the bearing member that is on a downstream side in a direction of rotation of the first rotatable member with respect to an intersection between the bearing member and a first virtual line extending from a center of rotation of the first rotatable member toward the pressing member in the direction in which the supporting member is retractably movable.

A medium transportation device includes a transportation driving roller that transports a medium; a roller unit including a separation roller as a driven roller that is rotated by rotation of the transportation driving roller and a shaft which penetrates a rotation center of the separation roller; a holder that detachably holds the roller unit; and a lock mechanism that switches between an unlocked state in which the roller unit is unlocked from the holder and a locked state in which the roller unit is locked to the holder.

A conveying apparatus includes: a rotation shaft; a conveying roller secured to the rotation shaft; a driven roller that cooperates with the conveying roller to convey a sheet at a nip position; a supporter supporting the rotation shaft rotatably; and a first guide and a second guide opposed to each other and defining a conveyance path guiding the sheet toward the nip position. The first guide and the second guide respectively have first and second guide surfaces defining the conveyance path. The first guide and the second guide respectively have first and second engaging portions engaged with the rotation shaft at positions different from a position of the supporter in the axial direction of the rotation shaft.

A rotating device includes a shaft member, a counterpart member, a bearing, and a retaining member. The counterpart member includes a shaft insertion portion into which the shaft member is inserted. The bearing is disposed in the shaft insertion portion and interposed between the counterpart member and the shaft member. The bearing causes the counterpart member and the shaft member to be rotatable relative to each other. The retaining member is disposed on an end portion of the shaft member on one side in an axial direction of the shaft member. The counterpart member includes an opposing portion closer to the end portion of the shaft member on the one side in the axial direction than the bearing. The opposing portion faces the retaining member in the axial direction.

A sheet conveyance device includes a conveyance roller having first and second end portions in a rotation axis direction, an open bearing supporting the first end portion, a frame supporting the open bearing, and a second end support portion supporting the second end portion. The open bearing includes a roller support portion supporting the conveyance roller and an open portion allowing the conveyance roller to be removed through the open portion from the roller support portion in a direction perpendicular to a rotation axis. The open bearing is movable from a first position, at which the conveyance roller is restricted from moving, to a second position at which the conveyance roller can move in the rotation axis direction. The second end portion is removable from the second end support portion by moving the conveyance roller from the second toward first end portion with the open bearing at the second position.

A sheet conveying apparatus configured to convey a sheet includes: a rotatable support portion configured to support a rotary portion which is configured to convey a sheet; an urging portion configured to urge the support portion in a direction of a rotary shaft center of the support portion with a support shaft, which is configured to support the support portion in a rotatable manner and is inserted through the urging portion; and a regulating portion configured to regulate a position of the support portion urged by the urging portion.

A roller support mechanism includes a pair of support plates, concave groove portions, and sliding bearing portions. The support plates are formed from an elastic material and disposed to face each other. The concave groove portions are formed in the support plates and each include an opening portion, two arc rims, and a straight line rim. The arc rims extend in a groove depth direction of the concave groove portion from opposite ends of the opening portion. The straight line rim extends straightly and connects extention ends of the arc rims. The sliding bearing portions have bearing holes in which a rotation shaft of a roller member is inserted. In a state where the rotation shaft is inserted in the bearing holes, the sliding bearing portions are pressed into the concave groove portions so as to be in close contact with their inner circumferential surfaces and unrotatably attached to them.

A transport device includes a drive roller and a driven roller. The drive roller transports paper-sheets in a predetermined transport direction by rotation thereof. The driven roller rotates with rotation of the drive roller, and regardless of from which direction the paper-sheets hit a contact point with the first roller, moves in a direction diagonally forward than a vertical direction with respect to the transport direction. The transport device further includes a bearing groove formed so that a shaft of the driven roller moves in a direction diagonally forward than the vertical direction with respect to the transport direction along an inclined surface.

A medium transportation device includes a transportation driving roller that transports a medium; a roller unit including a separation roller as a driven roller that is rotated by rotation of the transportation driving roller and a shaft which penetrates a rotation center of the separation roller; a holder that detachably holds the roller unit; and a lock mechanism that switches between an unlocked state in which the roller unit is unlocked from the holder and a locked state in which the roller unit is locked to the holder.