A paper feed apparatus comprises a paper feed section, a separation section, a rotating body and a control device. The paper feed section feeds an image receiving medium that is placed. The separation section is arranged at a downstream side of the paper feed section in a conveyance direction of the image receiving medium. If a plurality of the image receiving media fed from the paper feed section is overlapped, the separation section separates the plurality of the image receiving media that is overlapped. The rotating body is arranged at the upstream side of the separation section in the conveyance direction of the image receiving medium. The rotating body is capable of contacting with the placed image receiving medium. The rotating body is rotatable. The control device carries out control to rotate the rotating body at least before an operation of the paper feed section.

A sheet feeding device includes a stacking member, a feeding unit, and a detachable separation unit. The feeding unit feeds sheets stacked from the stacking member. The separation unit separates the fed sheets one by one. The separation unit includes a rotating member to abut and separate from the feeding unit and to rotate, a biasing member to bias the rotating member toward the feeding unit, and an engaged member to be engaged with an engagement member included in the sheet feeding device. The engagement member can move to a first position where the engagement member is engaged with the engaged member, and a second position away from the engaged member. Where the engagement member moves from the first to the second position when the separation unit is attached to the sheet feeding device, the separation unit moves in a detachment direction using the biasing member.

The present invention provides an image forming apparatus that reduces image artifacts caused by the back tension of a separating unit. A control unit decreases the number of rotations (the rotational speed) of a resist roller pair after the leading edge of a sheet reaches a transfer position.

In the first mode, the control unit controls the driving source such that the rotary feeding member starts to move toward the first position based on an elapse of a first time since the detection portion detected a leading edge of the sheet, and position the rotary feeding member at the first position when a trailing edge of the sheet passes through the separation nip. In the second mode, the control unit controls the driving source such that the rotary feeding member starts to move toward the first position based on an elapse of a second time longer than the first time since the detection portion detected the leading edge of the sheet, and position the rotary feeding member at a position separated more from the stacking portion than the first position when the trailing edge of the sheet passes through the separation nip.

A method for operating a paper feed system for use in a printing apparatus that detects multi-feeds and separates all sheets while allowing a single sheet to continue is disclosed. The separation method controls a motor for the separator roller that can be torque controlled, allowing varying torques depending on media type and/or user input. The separation method detects multi-feeds, correct the multi-feed, and ultimately feeds one sheet at a time through the automatic document feeder.

A paper feed system for use in a printing apparatus that detects multi-feeds and separates all sheets while allowing a single sheet to continue is disclosed. The separation system uses a motor for the separator roller that can be torque controlled, allowing varying torques depending on media type and/or user input. The separation system can also detect multi-feeds, correct them, and ultimately feed one sheet at a time through the automatic document feeder.

A sheet feed apparatus includes a sheet separation unit, and the sheet separation unit includes a separation roller that is provided so as to be brought into contact to an outer peripheral surface of a sheet feed roller, and separates a sheet fed by the sheet feed roller into one. The sheet separation unit comprises a hook for rotatably supporting the sheet separation unit in a main body casing of the sheet feed apparatus and an engaging claw that makes the sheet separation unit engage with the main body casing. Therefore, the sheet separation unit is held in the main body casing detachably.

A sheet feeding device includes a pickup roller, a feed roller, a retard roller, a conveyance rollers pair. The pickup roller contacts a sheet at a first contact point in a pickup position and rotates to convey the sheet in a predetermined conveyance direction. The feed roller is disposed on a downstream side of the pickup roller in the conveyance direction. The retard roller contacts the feed roller at a second contact point and conveys the sheet while separating the sheet. The conveyance rollers pair contacts each other at a third contact point and conveys the sheet passing through the second contact point to a conveyance path. The first contact point, the second contact point and the third contact point are disposed on a linear line in the conveyance direction, when viewed from axial directions of the rollers.

A sheet feeding apparatus includes a sheet stacking portion, and a sheet feeding unit having a rotary feeding member and a separation member defining a nip portion together with the rotary feeding member, with the nip portion separating the sheet fed by the rotary feeding member from another sheet. A load detecting unit detects a conveyance load acting on the sheet feeding unit while feeding the sheet, and a control unit controls the sheet feeding unit to start to feed a second sheet succeeding to a first sheet at a first timing in a case where the conveyance load detected while feeding the first sheet is less than a threshold value, and starts to feed the second sheet at a second timing which is later than the first timing in a case where the conveyance load detected while feeding the first sheet exceeds the threshold value.

The present invention provides an image forming apparatus that reduces image artifacts caused by the back tension of a separating unit. A control unit decreases the number of rotations (the rotational speed) of a resist roller pair after the leading edge of a sheet reaches a transfer position.