until the lower limit sensor sn5 turns on then a tray full signal is again transmitted to the copier body when this kind of operation overlaps with the tray shifting operation stated earlier the former will be performed later with priority given to the latter when the last paper sheet moves away from a copier discharge sensor 215 fig9 the copier body sends a finisher stop signal to the finisher in response the elevation motor m3 is energized after the last paper sheet has been fed out onto the tray 107 whereby the tray 107 is lowered by a predetermined amount to facilitate the removal of the paper sheets assume that the shifting operation is not executed at the time of the turn on of power supply and instead a shift mode or a proof mode is selected at the time of mode selection then in response to a mode signal the shift motor m2 is energized to shift the discharge tray 107 and on the turn on of the shift sensor 117 deenergized this is to sort a stack of paper sheets existing on the tray 107 and a stack of paper sheets which will be stacked by the next job such a sorting operation will be executed only after the up down movement of the tray 107 is completed more.