A transmission gear is movable in an axial direction between a first position separated from an output gear and a second position coupled to the output gear in a state where the transmission gear engages with an input gear. The input gear is configured to: by rotating in a first direction by receiving driving force from a drive source, move the transmission gear from the first position to the second position and transmit driving force in the first direction to the output gear via the transmission gear; and by rotating in a second direction, move the transmission gear from the second position to the first position and cancel transmission of driving force to the output gear. The transmission gear is configured to, when the output gear rotates in a state where the transmission gear is located at the first position, not be coupled to the output gear.

A sheet processing device sandwiches a sheet-shaped medium in a two-ply sheet in which two sheets are overlaid and partially bonded. The sheet processing device includes a separator, a conveyor, and a switching member. The separator separates the two sheets of the two-ply sheet. The conveyor is disposed downstream from the separator in a sheet conveyance direction and conveys the two-ply sheet. The switching member is disposed downstream from the conveyor in the sheet conveyance direction. The switching member switches a conveyance path of the two-ply sheet to convey the two-ply sheet to a fixing path on which fixing processing is performed on the two-ply sheet or a non-fixing path on which no fixing processing is performed on the two-ply sheet.

There is provided a feed apparatus including a support unit, a feed roller, a swingable arm to support the feed roller, a guide unit, a movable member movable to a retracted position and a protruding position at which the movable member can abut against the sheet supported by the support unit, a driving source, driving transmission units; and a contact-separating mechanism to move the feed roller to a separated position and an abutment position at which the feed roller abuts against the sheet supported by the support unit. In a state in which the movable member is the protruding position and the feed roller is the separated position, a time required to start feeding of the sheet by the feed roller moved from the separated position to the abutment position is longer than a time required to shift the movable member from the protruding position to the retracted position.

An image forming apparatus includes a first side plate, a second side plate and a sheet feeding unit. The first and second side plates are opposite to each other. The sheet feeding unit is attached between the first and second side plates. The sheet feeding unit has a feed frame, a pickup roller, a feed roller, a separation member and a weight member. The feed frame has a first side wall supported by the first side plate in a facing manner and a second side wall supported by the second side plate in a facing manner. The pickup roller and the feed roller are supported in the feed frame. The separation member forms a nip and separates the sheet at the nip. The weight member is disposed above the feed roller in the feed frame and configured to damp vibration of the feed frame.

A drive transmission device (6) includes a first drive train (62) and a second drive train (63). The first drive train (62) includes a first gear (621), a second gear (622), a rotary shaft (623), and one-way clutches (624). The second drive train (63) includes a third gear (631), a fourth gear (632), a rotary shaft (633), and an electromagnetic clutch (634). The third gear (631) engages the first gear (621) and the fourth gear (632) engages the second gear (622). A rotational speed of a pickup roller (12) is switched by switching on/off the electromagnetic clutch (634) to change a transmission path of driving force.

A sheet feeder includes a sheet platen, a pickup roller, a feeding roller, a regulating portion, a driving mechanism, a feeding control unit, a sheet sensor, and a determination processing unit. The feeding control unit executes a feeding operation by rotationally driving the pickup roller and the feeding roller in a state where the regulating portion is located at a retreating position. The sheet sensor is located at a downstream side in the feeding direction of the feeding roller. The determination processing unit determines whether the sheet feeding has succeeded or not based on a signal from the sheet sensor. After a start of the feeding operation, when the determination processing unit determines that the sheet feeding has failed, the feeding control unit once moves the regulating portion located at the retreating position to the abutting position and then executes the feeding operation again.

An image recording apparatus including a first tray having a first holding portion for holding sheets, a second tray disposed above the first tray and including a second holding portion for holding sheets, a sheet feeder that selectively feeds a sheet from one of the first tray and the second tray in a sheet feed direction, a recording unit that records an image on the sheet fed by the sheet feeder, and a discharge roller that discharges the sheet on which the image is recorded by the recording unit. The second holding portion of the second tray moves above the first holding portion of the first tray. The second tray further includes a discharged sheet receiving portion for receiving the sheet discharged by the discharge roller. The second tray including the discharged sheet receiving portion pivots relative to the first tray.

A motor control unit controls a driving current that flows through a coil of a motor to be driven, by controlling a PWM signal supplied to an H bridge circuit constituted by FETs. A current value generation unit detects a driving current based on a voltage that occurs across a current detection resistor, and corrects a detection value by using a first or second correction value. The current value generation unit, if the driving current is detected in the H period of the PWM signal, corrects the detection value by using the first correction value, and if the driving current is detected in the L period of the PWM signal, corrects the detection value by using the second correction value that has a polarity different from a polarity of the first correction value.

A feeding device includes a roller configured to feed an uppermost sheet of a plurality of sheets stacked in a stacking unit, and an inclined separator located downstream of the roller in a feed direction and configured to separate one sheet from another sheet. The inclined separator includes a first separator and a second separator that are arranged along the feed direction. Resistance imparted to each sheet by the first separator is greater than resistance imparted to each sheet by the second separator.

A driving force transmission device includes a drive gear, a driven gear, which includes a gear portion and a partially toothless gear portion, rotates by the gear portion meshing with the drive gear, stops rotating in response to the partially toothless gear portion facing the drive gear, a first cam member and a second cam member which operate in conjunction with the driven gear, a first elastic member for urging the first cam member, a follower member to which urging force is applied by a second elastic member and which is moved by the second cam member, and a contact portion for coming into contact with the first cam member by urging force of the first elastic member. The first cam member includes a home cam surface for coming into contact with the contact portion so that rotation of the driven gear is limited.