A sheet processing apparatus comprises at least one roller disposed in a sheet conveyance path and configured to convey a plurality of sheets; a sheet sensor disposed in the sheet conveyance path and configured to detect each sheet as it is conveyed by a particular roller of the at least one roller and to generate sensor information indicative of the detection; and a controller configured to: use the sensor information to calculate a sheet passage interval for each sheet; count a first number of times the sheet passage interval is greater than a first threshold corresponding to abnormally slow sheet conveyance and a second number of times the sheet passage interval is lower than a second threshold corresponding to abnormally fast sheet conveyance; determine whether an alert condition has been met based on the counts of the first and second numbers of times; and generate a control signal after the alert condition has been met.

A sheet conveyor includes a feed roller configured to contact a sheet from above and feed the sheet in a sheet feed direction, a frictional member disposed downstream from the feed roller, a separation roller disposed downstream from the feed roller and facing the frictional member from above, and a guide portion located downstream from the feed roller and upstream from the separation roller. The guide portion includes a pointed portion located above a portion of a common tangent to the feed roller and the separation roller when viewed in a cross section that is orthogonal to an axial direction of the feed roller and an axial direction of the separation roller. The pointed portion is located along a width direction of the sheet. The guide portion is configured to guide the sheet fed over the pointed portion toward a nip between the separation roller and the frictional member.

A paper feeder including: a push-up mechanism that pushes up an end portion of a tray below a leading end of a stack of sheets; a paper feed roller that intersects a locus fitted to motion of the end portion of the tray or an extension of the locus in the direction of the motion, and applies a conveying force to a sheet that the push-up mechanism presses against the paper feed roller to move the sheet in a conveyance direction; a separation member that forms a nip with the paper feed roller and applies a resistance force in a direction opposite the conveyance direction to the sheet; and an auxiliary roller upstream in the conveyance direction from the locus that applies a conveying force in the conveyance direction to the sheet, maintaining a state of contact between the sheet and the paper feed roller.

A sheet supplier, including: a tray including a sheet support surface; a sheet supply roller configured to supply an uppermost one of sheets; a rotational member configured to contact a lowermost one of the sheets; a presser configured to press the supply roller relative to the rotational member; and a supporter configured to support the rotational member by a contact portion such that the rotational member is rotated by a movement of the lowermost sheet and to limit a movement of the rotational member caused by a force of the lowermost sheet in a sheet supply direction; wherein, where static friction coefficients between the supply roller and the uppermost sheet, between the sheets on the support surface, between the rotational member and the lowermost sheet, and between the rotational member and the contact portion are respectively defined as 2, 3, and 4, the following expressions are satisfied: 1>4>2, 3>4.

A sheet conveying device, which is included in an image forming apparatus and an optional device attachable to the image forming apparatus, includes a sheet container, a sheet feeder, a separator, a guide, and a projection. The sheet container loads multiple sheets. The sheet feeder feeds a sheet out of the multiple sheets in the sheet container. The separator separates the sheet from another sheet fed together with the sheet. The guide having a guide surface to guide the sheet passing the separator such that the sheet is fed in a predetermined sheet conveying direction. An upstream end in the sheet conveying direction of the guide surface of the guide is located lower than a downstream end in the sheet conveying direction of the separator. The projection is disposed facing the separator at the upstream end in the sheet conveying direction of the guide surface.

A sheet feeding apparatus includes a disengagement mechanism to disengage a rotary feeding member and a separation member to be apart from each other, a pressing portion to press an upper face of a sheet supported on a sheet supporting portion, and a detector to detect displacement of the sheet pressed by the pressing portion. A controller executes one mode among a plurality of modes to feed the sheet supported on the sheet supporting portion based on a detection result of the detector. In a first feed mode, a leading edge of the sheet passes a position of a separation portion with the rotary feeding member and the separation member disengaged by the disengagement mechanism. In a second feed mode, the leading edge of the sheet passes the separation portion with the rotary feeding member and the separation member engaged.

In accordance with an embodiment, a paper feed apparatus comprises a paper feed section, a separation section, an abutting section and a friction force variable section. The paper feed section feeds an image receiving medium. The separation section is arranged at the downstream side of the paper feed section in a conveyance direction of the image receiving medium. In a case in which 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 abutting section abuts against the image receiving medium fed from the paper feed section. The friction force variable section changes a friction force of the abutting section against the image receiving medium.

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 including: a sheet feeding tray configured to support a sheet; and an apparatus main body configured to support the sheet feeding tray so as to be moveable in a direction parallel with a sheet feeding direction, the apparatus main body including a chute configured to guide the sheet that is fed from the sheet feeding tray, wherein the sheet feeding tray includes a guiding member configured to be displaced between an engaging position at which the guiding member engages with the chute and restrains movement of the sheet feeding tray and a separation position at which the guiding member separates from the chute and permits movement of the sheet feeding tray, and wherein the guiding member is configured to guide the sheet that is fed from the sheet feeding tray toward the chute when the guiding member is located at the engaging position.

A sheet feeding apparatus includes a sheet supporting portion including a supporting surface, an abutment portion against which a leading edge of the sheet abuts, a feeding rotator configured to feed the sheet, a first friction member provided on the supporting surface so as to face the feeding rotator, the first friction member including a first friction surface having a static friction coefficient greater than that of the supporting surface, a trailing end supporting portion configured to support a trailing end portion of the sheet curved upward, and a second friction member disposed upstream of the first friction member in the sheet feeding direction on the supporting surface, the second friction member including a second friction surface which has a static friction coefficient greater than that of the supporting surface and is configured to be in contact with the sheet supported by the supporting surface.