Sheet stacking method for use in printing machine, involves providing interfering signal to machine control when time period for covering vacuum bar with printed sheet exceeds determined time slot, for stopping machine

摘要

The method involves determining a time slot and a time period for covering a vacuum bar (10) with a printed sheet (B) during deceleration of a paper lift (8). The covering of the vacuum bar with the sheet is determined by a sensor. An interfering signal is provided to a machine control when the time period exceeds the time slot. A signal for stopping a printing machine is generated based on the interfering signal. An independent claim is also included for an apparatus for stacking sheets.