Sheet feeding unit and image forming apparatus

A sheet feeding unit comprising:

• a feeding roller that is formed into a non-circular shape, and includes an arcuate portion to feed a sheet and a notched portion cut out part;
• a drive motor configured to drive the feeding roller;
• a driving force transmission mechanism configured to transmit a driving force from the drive motor to the feeding roller;
• a one rotation control mechanism, provided in the driving force transmission mechanism, configured to control the rotation of the feeding roller;
• a curved sheet feeding path downstream of the feeding roller in the sheet feeding direction;
• a conveying roller, provided downstream of the curved sheet feeding path, configured to receive and convey the sheet fed from the feeding roller and to be set to a sheet conveyance speed greater than that of the feeding roller to eliminate a loop formed when the sheet fed by the feeding roller is passing through the sheet feeding path during the one rotation control of the feeding roller by the one rotation control mechanism;
• and
• a one-way rotation control mechanism configured to stop the transmission of the driving force from the drive motor to the feeding roller in the case that the arcuate portion of the feeding roller is pulled by the sheet being conveyed by the conveying roller in the course of the one rotation control of the feeding roller, and to cause the drive motor to be coupled again with the feed roller to transmit the driving force and perform the one rotation control on the feeding roller after the arcuate portion which is rotated by the sheet leaves the sheet and hence the feeding roller is stopped.