Installation identifying register marks on colour printing machines - locates marks on reading tracks and checks by fixed optical sensor system

The installation identifies register marks positioned on a running track along two reading tracks next to each other and checked by two rigidly fixed optical sensor systems also lying next to each other. The tracks are investigated for their relative position to each other. At least one of the register marks is located in front of a set sequence of further check marks. Gaps are picked up sequentially by the sensor systems before the register marks. The signals emitted by the sensor systems are then examined for the pre-set sequence of check marks and gaps.