A sheet feeder includes a controller configured to perform a driving process of supplying a motor with an electric current to rotate a roller, perform a stopping process of stopping supplying the electric current in response to determining that the motor has not rotated before a second sensor detects a sheet, when an accumulated rotational quantity of the roller is less than a threshold, set a retry upper limit to a first value, the accumulated rotational quantity being detected by a first sensor in the driving process performed for a first time, when the accumulated rotational quantity of the roller is equal to or more than the threshold, set the retry upper limit to a second value more than the first value, and repeatedly perform the driving process and the stopping process until a number of retries reaches the retry upper limit or until the second sensor detects the sheet.

A sheet conveying device includes a conveyor for conveying a sheet along a predetermined conveyance path and a feeder unit for supporting the sheet to be fed to the conveyor. The conveyor includes a first guide part for guiding the sheet toward a downstream side in the conveying direction in a direction inclined at a downward gradient, a second guide part for guiding the sheet from the first guide part toward a further downstream side in a direction inclined at an upward gradient, a suction roller arranged at the first guide part for conveying the sheet supported by the feeder unit toward the downstream side, and a first conveyance roller arranged at the second guide part and for conveying the sheet conveyed by the suction roller toward the downstream side one at a time.

A paper feed apparatus includes a paper feeding roller and a separating pad for separating paper one by one and feeding the paper. This separating pad is supported by a separating pad holder to be abutted onto the paper feeding roller with a predetermined pressure. Furthermore, the separating pad holder is provided with a weight member in a loosely-fitted state.

A sheet supplying device is provided. The sheet supplying device includes a separator to separate sheets one by one. The separator includes a separation pad, a spring, and a separation pressure adjuster. The separation pad contacts each of the sheets. The spring applies a separation pressure to the separation pad. The separation pressure adjuster adjusts the separation pressure to one of separation pressure values variable in multiple steps.

A sheet separating apparatus includes a stacker having a sheet supporting surface, a separation roller rotating around a first shaft center parallel to a width direction of the sheet supporting surface, contacting a sheet fed from the stacker and conveying the sheet to a downstream side in a conveyance direction perpendicular to the width direction, a separation piece facing the separation roller and separating the sheet one at a time in cooperation with the separation roller, the separation roller and the separation piece nipping the sheet at a first nip position, and a pinch roller provided on an upstream side with respect to the first nip position and abutting on the separation roller to be rotatable around a second shaft center parallel to the width direction, the pinch roller having a portion overlapping the separation piece as seen from the width direction.

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 feeder, which can be included in an image forming apparatus, includes a rotary body to contact and feed a recording medium to a downstream side along a sheet conveying path, a friction body disposed facing and contacting the rotary body with the sheet conveying path interposed therebetween, the friction body forming a separation nip region with the rotary body, a receiver to support the friction body at a position opposite to the separation nip region, and multiple projections to guide the recording medium toward the separation nip region. Each of the multiple projections extends toward the rotary body at respective axial ends of the rotary body and has a top face disposed upstream from the separation nip region in a sheet conveying direction between an outer circumferential surface of the rotary body and a surface of the friction body.

A sheet feeder, which is included in an image forming apparatus, includes a sheet feeding unit to feed a sheet, a sheet separating unit disposed opposite the sheet feeding unit to separate the sheet together with the sheet feeding unit, a bottom plate on which the sheet is loaded, a pressing unit having a leading end and movably disposed between the bottom plate and the sheet separating unit, and a support to rotatably support the pressing unit such that the leading end of the pressing unit contacts and separates from the sheet feeding unit.

A sheet conveying apparatus, including: a base body having a conveyor surface; a separating roller configured to rotate about a first rotation axis parallel to a width direction of the conveyor surface and to convey a sheet downstream in a conveyance direction orthogonal to the width direction; a separating piece opposed to the separating roller and configured to cooperate with the separating roller to separate sheets being conveyed one by one; an attachment member removably attached to the base body at a position at which the attachment member is opposed to the separating roller, so as to form a part of the conveyor surface; a holder holding the separating piece and supported by the attachment member so as to be movable toward and away from the separating roller; and a first urging member provided between the attachment member and the holder for urging the separating piece toward the separating roller.

The sheet feeding apparatus of the invention includes a sheet stacking portion, a rotating body, a contact member, a conveyance guide, a driving source, a shutter member and a torque limiter. The torque limiter is disposed between the rotating body and the driving source, transmits a driving force of the driving source to the rotating body in a state that a load in the sheet feeding direction of less than a predetermined torque is applied to the rotating body, and not transmit the driving force of the driving source to the rotating body in a state that the load in the sheet feeding direction of more than the predetermined torque is applied to the rotating body.