Image forming system

An image forming system, comprising:

• an image forming apparatus including:
• a sheet storage portion that stores recording sheets;
• a first feed portion that feeds one by one the recording sheets from the sheet storage portion downstream in a sheet feeding direction;
• and
• an image forming portion that forms images on the recording sheets fed by the first feed portion;
• a first conveyance path that conveys the recording sheets fed from the first feed portion to a discharge port;
• a sheet feeding unit including:
• a sheet stacking portion on which insertion sheets are stacked;
• a second feed portion that feeds one by one the insertion sheets stacked on the sheet stacking portion;
• and
• a relay conveyance portion that receives the recording sheets fed by the first feed portion and the insertion sheets fed by the second feed portion to convey them downstream in the sheet conveyance direction,
• the sheet feeding unit being coupled to the image forming apparatus on a downstream side thereof;
• a sheet post-processing unit coupled to the sheet feeding unit on a downstream side thereof, the sheet post-processing unit forming a bundle of sheets containing the insertion sheets and the recording sheets and performing predetermined post-processing on the bundle of sheets;
• a controller that controls the image forming apparatus, the sheet feeding unit, and the sheet post-processing unit, wherein
• the sheet feeding unit includes a remaining amount detecting portion that detects a remaining amount of the insertion sheets on the sheet stacking portion,
• the relay conveyance portion includes a merge portion at which an insertion conveyance path for conveying the insertion sheets merges with a relay conveyance path for conveying the recording sheets, and
• when, during continuous printing, an existing number of the recording sheets present in a conveyance path including the first conveyance path and the relay conveyance path is more than a constituting number of the recording sheets contained in the bundle of sheets and the remaining amount of the insertion sheets detected by the remaining amount detecting portion is equal to or less than a predetermined amount level, the controller controls feeding of the recording sheets from the first feed portion such that the existing number of the recording sheets in the conveyance path is less than the constituting number of the recording sheets.