An image forming apparatus includes: one paper cassette configured to accommodate a paper sheet; an image forming section provided above the paper cassette to form an image on the paper sheet; a main conveying path configured to convey the paper sheet; and a reverse conveying path configured to reverse the paper sheet, wherein the reverse conveying path includes: a first reverse conveying path provided side by side with the paper cassette to extend vertically; a second reverse conveying path configured to connect from the first reverse conveying path and extend below the paper cassette; a guide plate configured to open and close the first reverse conveying path and release pressure of a pair of paper conveying rollers; and an entry restricting unit provided at a boundary point between the first reverse conveying path and the second reverse conveying path to open and close a conveying course of the paper sheet.

In some examples, a sheet processing machine includes at least one sensor device that includes at least two sensors configured as a camera. The sheet processing machine further includes at least one infeed system. The at least one sensor device is configured to control, by open-loop control and/or closed-loop control, at least one servo drive of the infeed system as a function of at least one sheet of sheets being detected by the at least two sensors. The at least two sensors are configured to selectively detect at least one edge and/or printing mark of the sheets. Some examples likewise relate to a method for controlling, by open-loop control and/or closed-loop control, at least one component of a sheet processing machine.

A first sheet conveying path extends from a sheet supply portion toward a sheet discharge portion. A second sheet conveying path extends, from a diverging position in the first sheet conveying path, toward a switch-to-back portion. A third sheet conveying path is a conveying path for the sheet that is reversed by the switch-to-back portion. A first movable guiding portion is rotatable between a first posture in which the sheet that has reached the diverging position is guided toward the sheet discharge portion, and a second posture in which the sheet is guided into the second conveying path. A second movable guiding portion is rotatable between a third posture and a fourth posture, in the second sheet conveying path. In the third posture, the second sheet conveying path is formed in conjunction with the first movable guiding portion. In the fourth posture, the third sheet conveying path is formed.

A first sheet conveying path extends from a sheet supply portion toward a sheet discharge portion. A second sheet conveying path extends, from a diverging position in the first sheet conveying path, toward a switch-to-back portion. A third sheet conveying path is a conveying path for the sheet that is reversed by the switch-to-back portion. A first movable guiding portion is rotatable between a first posture in which the sheet that has reached the diverging position is guided toward the sheet discharge portion, and a second posture in which the sheet is guided into the second conveying path. A second movable guiding portion is rotatable between a third posture and a fourth posture, in the second sheet conveying path. In the third posture, the second sheet conveying path is formed in conjunction with the first movable guiding portion. In the fourth posture, the third sheet conveying path is formed.

A sheet skew feed correcting apparatus is provided which includes: a driving rotation member that is driven to rotate; a first driven rotation member that is pressure contacted against the driving rotation member; a first holder rotatably holding the first driven rotation member; a second driven rotation member that is pressure contacted against the driving rotation member; a second holder rotatably holding the second driven rotation member; and a shutter portion with which a leading end of a sheet comes into contact for skew feed correction, the shutter portion moving pivotally with one end portion thereof supported by the first holder and another end portion thereof supported by the second holder; wherein the shutter portion has abutting portions with which the leading end comes into contact, and a coupling portion extending so as to couple the abutting portions together between the first and the second driven rotation members.

A sheet skew feed correcting apparatus is provided which includes: a driving rotation member that is driven to rotate; a first driven rotation member that is pressure contacted against the driving rotation member; a first holder rotatably holding the first driven rotation member; a second driven rotation member that is pressure contacted against the driving rotation member; a second holder rotatably holding the second driven rotation member; and a shutter portion with which a leading end of a sheet comes into contact for skew feed correction, the shutter portion moving pivotally with one end portion thereof supported by the first holder and another end portion thereof supported by the second holder; wherein the shutter portion has abutting portions with which the leading end comes into contact, and a coupling portion extending so as to couple the abutting portions together between the first and the second driven rotation members.

In order to provide a configuration capable of suppressing reductions in productivity of sheets, a pair of regulation guides are capable of guiding opposite end edges in a sheet width direction Y of a sheet S1 conveyed by a conveyance belt and spheres, while being nipped. Further, the pair of regulation guides are capable of shifting to guide positions for guiding the opposite end edges of the sheet, and retract positions retracted from the opposite end edges of the sheet more than the guide positions. A sheet detecting sensor is disposed on the downstream side of the conveyance belt in a conveyance direction X to detect the presence or absence of the sheet.

In order to provide a configuration capable of stably performing conveyance of sheets, a pair of regulation guides are capable of guiding opposite end edges in the sheet width direction Y of a sheet S conveyed by a conveyance belt and spheres, while being nipped. Further, the pair of regulation guides are capable of shifting to guide positions for guiding the opposite end edges of the sheet and retract positions retracted from the opposite end edges of the sheet more than the guide positions. In shifting the pair of regulation guides from the retract positions to the guide positions, a guide shift section causes the one of regulation guides to arrive at the guide position after the other of regulation guides arrives at the guide position.

In order to provide a configuration capable of stably performing conveyance of sheets, a pair of regulation guides are capable of guiding opposite end edges in the sheet width direction Y of a sheet S conveyed by a conveyance belt and spheres, while being nipped. Further, the pair of regulation guides are capable of shifting to guide positions for guiding the opposite end edges of the sheet and retract positions retracted from the opposite end edges of the sheet more than the guide positions. In shifting the pair of regulation guides from the retract positions to the guide positions, a guide shift section causes the one of regulation guides to arrive at the guide position after the other of regulation guides arrives at the guide position.

An image reading apparatus includes a first opening/closing unit to openably and closeably support a sheet conveyance portion with respect to an image reading portion, and a second opening/closing unit to openably and closeably support the sheet conveyance portion with respect to the image reading portion. The first opening/closing unit includes a first spring to urge the sheet conveyance portion in a direction in which the sheet conveyance portion moves from a closed position toward an opened position, and the second opening/closing unit includes a second spring to urge the sheet conveyance portion in the direction in which the sheet conveyance portion moves from the closed position toward the opened position and an oil damper to attenuate vibration energy of the sheet conveyance portion. The first opening/closing unit does not include an oil damper.