A sheet punching apparatus includes a waste box formed of insulating resin, a detection sensor provided in the waste box and configured to detect the amount of paper chips in the waste box, and a conductive member disposed such that at least a part thereof is positioned in midair in the waste box below the detection sensor. With this configuration, erroneous detection of the detection sensor can be prevented.

A sheet processing apparatus includes a first conveyance rotary member, a second conveyance rotary member, a punch member, a sensor, a punch motor, a conveyance motor, a first drive transmission portion including a first number of drive transmission members configured to sequentially transmit driving force of the conveyance motor to the first conveyance rotary member, and a second drive transmission portion including a second number of drive transmission members configured to sequentially transmit driving force of the conveyance motor to the second conveyance rotary member, the second number being larger than the first number.

A sheet processing apparatus includes a puncher, a first sensor positioned upstream of the puncher in the conveyance direction, a second sensor positioned upstream of the first detection position in the conveyance direction, a drive source configured to drive the puncher, a controller configured to control the drive source. The controller executes a control mode including a first process of controlling a rotation speed of the puncher on a basis of a detection result of the second sensor and a second process of controlling the rotation speed of the puncher on a basis of a detection result of the first sensor. In the control mode, the controller does not stop rotation of the puncher in a period between the punching process on the preceding sheet and a punching process on the succeeding sheet.

A sheet post-processing apparatus that performs post-processing on a sheet on which an image is formed includes: a punch hole forming portion; and a sheet bundle forming portion that has a conveyance portion, stops a first sheet on a conveyance path, and conveys a second sheet after the first sheet to a position overlapping the first sheet to form a sheet bundle. The sheet post-processing apparatus includes a shift portion to make a shift so that a relative position between the first sheet and the second sheet in a direction orthogonal to a conveyance direction becomes a relative position at which the second sheet does not overlap a punch hole of the first sheet to make the second sheet overlap the first sheet, and forms a sheet bundle in which sheets overlapped with each other are deviated in a width direction.

A series of conveyance paths to convey a recording medium is formed across a printer and a post-processing device in a printing system. The printing system includes: a detection unit that detects that the post-processing device has entered a predetermined state; and a paper feeding control unit that limits the number of recording media fed to the conveyance path, when it is not detected that the post-processing device has entered the predetermined state, based on the number of recording media conveyable to the post-processing device after the post-processing device enters the predetermined state.

A sheet conveying device has a body and a frame supporting it, and is insertable or extractable along a sheet stacking face formed in an in-body discharge space in an image forming apparatus and having an inclined face with an upward gradient toward the downstream side in the sheet discharge direction. On the face of the frame opposite the sheet stacking face, a plurality of first and second wheels rotatable in the insertion or extraction direction are provided downward of the center of the opposite face in the insertion direction. The first wheels are arranged downstream of the second wheels in the insertion direction, and protrude from the opposite face farther than the second wheels. The first wheels fit into a concave portion formed in the sheet stacking face by the inclined face and thereby enable the second wheels to make contact with the sheet stacking face.

A punching apparatus, including: a punching portion configured to punch a sheet; and a chad box configured to store a chad of a sheet punched by the punching portion, wherein the chad box includes: a first inner wall portion formed of an insulator; and a second inner wall portion formed of a conductor and arranged above the first inner wall portion.

A post-processing apparatus includes a post-processing unit configured to receive sheets from an image forming apparatus, perform processing on the received sheets, and then discharge the processed sheets through a discharge port. A sensor is configured to detect a presence of an object at the discharge port. The sensor includes a first light emitter on a first side of the discharge port that is positioned to emit a light across a width of the discharge port, a reflector on a second side of the discharge port opposite the first side in a first direction, and a first light receiver positioned to receive light of the first light emitter from the reflector. A controller is configured to terminate the processing on the received sheets by the post-processing unit when the sensor detects the presence of the object at the discharge port.

A sheet post-processing apparatus that performs post-processing on a sheet on which an image is formed includes: a punch hole forming portion; and a sheet bundle forming portion that has a conveyance portion, stops a first sheet on a conveyance path, and conveys a second sheet after the first sheet to a position overlapping the first sheet to form a sheet bundle. The sheet post-processing apparatus includes a shift portion to make a shift so that a relative position between the first sheet and the second sheet in a direction orthogonal to a conveyance direction becomes a relative position at which the second sheet does not overlap a punch hole of the first sheet to make the second sheet overlap the first sheet, and forms a sheet bundle in which sheets overlapped with each other are deviated in a width direction.

A post-processing apparatus to perform a post-processing for a sheet conveyed from an image forming apparatus includes a punching unit, first and second motors, and a control unit. The punching unit includes a punch that is rotated by the first motor to punch the sheet, and a moving unit moved by the second motor to move the punch in a width direction intersecting with a sheet conveying direction. The control unit controls at least the first motor. In a first section from a first position in which the punch starts punching the sheet to a second position in which the punching ends, the control unit sets a current value for driving the first motor to a first current value. In a second section other than the first section, the control unit can set the first motor driving current value to a second current value lower than the first current value.