The sheet processing device includes a processing tray, a processing device, a discharge port, a discharge rollers pair, a supporting arm and an interlock mechanism. The discharge rollers pair has a lower roller and an upper roller. The supporting arm supports the upper roller and is turnable between a first position where the upper roller comes into contact with the sheet and a second position where the upper roller separates upwardly from the sheet. The interlock mechanism includes an actuator, a switch and a switch moving mechanism. The actuator is turned with an upwardly turning of the supporting arm. The switch detects the actuator to detect that the supporting arm is turned to the second position. The switch moving mechanism moves the switch to a switch non-detective position when the processing is not performed and moves the switch to a switch detective position when the processing is performed.

An image forming apparatus includes a processing tray, a post-processing controller, and a detection sensor. The processing tray is configured to support a sheet or a sheet bundle on which a post-processing is to be executed. The post-processing controller is configured to execute the post-processing on the sheet positioned on the processing tray. The detection sensor is configured to detect an object in a predetermined detection range including a space above the processing tray. The post-processing controller stops execution of the post-processing when the detection sensor detects the object at a determination timing other than a timing at which passage of the sheet or the sheet bundle through the detection range is estimated.

An image forming apparatus includes a processing tray, a post-processing controller, and a detection sensor. The processing tray is configured to support a sheet or a sheet bundle on which a post-processing is to be executed. The post-processing controller is configured to execute the post-processing on the sheet positioned on the processing tray. The detection sensor is configured to detect an object in a predetermined detection range including a space above the processing tray. The post-processing controller stops execution of the post-processing when the detection sensor detects the object at a determination timing other than a timing at which passage of the sheet or the sheet bundle through the detection range is estimated.

Provided is a technique that enables proper sorting of discharged print media by suppressing curling of each of the print media sufficiently. A determining unit determines a curling suppressing operation to be executed such that in a case where sorting operation is executed, the suppressing operation having a higher effect of suppressing curling is executed than in a case where the sorting operation is executed. Then, a print control unit controls a print head to perform printing on print media while executing the suppressing operation determined by the determining unit.

Provided is a technique that enables proper sorting of discharged print media by suppressing curling of each of the print media sufficiently. A determining unit determines a curling suppressing operation to be executed such that in a case where sorting operation is executed, the suppressing operation having a higher effect of suppressing curling is executed than in a case where the sorting operation is executed. Then, a print control unit controls a print head to perform printing on print media while executing the suppressing operation determined by the determining unit.

An image forming apparatus includes a first detection unit, a second detection unit, a first conveyance unit, a second conveyance unit, which is provided on downstream in the conveyance direction with respect to the first detection unit and is configured to convey sheets, and a control unit. When the first detection unit does not detect a trailing edge of a first sheet before a first timing, the control unit stops the drive of the first conveyance unit and continues drive of the second conveyance unit, and when the second detection unit detects the trailing edge of the first sheet before a second timing later than the first timing, the control unit re-drives the first conveyance unit or stops the drive of the second conveyance unit in accordance with a sheet length of the first sheet in the conveyance direction.

An image forming apparatus includes a first detection unit, a second detection unit, a first conveyance unit, a second conveyance unit, which is provided on downstream in the conveyance direction with respect to the first detection unit and is configured to convey sheets, and a control unit. When the first detection unit does not detect a trailing edge of a first sheet before a first timing, the control unit stops the drive of the first conveyance unit and continues drive of the second conveyance unit, and when the second detection unit detects the trailing edge of the first sheet before a second timing later than the first timing, the control unit re-drives the first conveyance unit or stops the drive of the second conveyance unit in accordance with a sheet length of the first sheet in the conveyance direction.

A paper conveyance device includes a paper feed unit, a conveyance rotator, a conveyance guide, a multi-feed detection unit, and a control unit. The control unit causes an ultrasonic sensor to transmit an ultrasonic wave in a detection section. The control unit sets a detection execution section and a detection skip section in the detection section. The control unit does not determine whether multi-feed has occurred in the detection skip section. The control unit sets the detection skip section based on a time point at which vibration is applied to conveyed paper.

A paper conveyance device includes a paper feed unit, a conveyance rotator, a conveyance guide, a multi-feed detection unit, and a control unit. The control unit causes an ultrasonic sensor to transmit an ultrasonic wave in a detection section. The control unit sets a detection execution section and a detection skip section in the detection section. The control unit does not determine whether multi-feed has occurred in the detection skip section. The control unit sets the detection skip section based on a time point at which vibration is applied to conveyed paper.

An image forming apparatus includes a sheet storing cassette, a lift mechanism, a sheet feeding portion, a remaining quantity sensing portion, and a control portion. The control portion, during continuous sheet feeding by the sheet feeding portion, controls the lift mechanism to make a sheet stacking plate ascend to a lifted position where sheets make contact with the sheet feeding portion, and feeds a foregoing sheet and then, at a sheet feeding timing a predetermined time thereafter, starts feeding the following sheet. The control portion makes the sheet feeding timing earlier as the remaining quantity of the sheets sensed by the remaining quantity sensing portion decreases.