Recording sheet stacking apparatus in image recording system

摘要

A sheet stacking mechanism for use in apparatuses wherein an image is recorded on both sides of a recording sheet, including a bumper roller which is capable of retractably shifting to a downward position to be in pressure contact with the recording sheets on an intermediate tray and transport the recording sheets to a stopper where the leading edges thereof are aligned and, a sensor and control device for controlling the position of the roller so that the roller is shifted downward onto the recording sheet to be aligned when the sheets reach the tray, and raised out of contact with the sheets when the leading edges reach the stopper.