Method and device for recognition of a tear-off strip on a material web

摘要

In order to check a material web ( 12 ), in particular a film web, with regard to the correct arrangement of a tear-off strip ( 11 ) extending in the longitudinal direction of the material web ( 12 ), ultrasonic transmitters are used, specifically an ultrasonic transmitter ( 11 ) on the one hand and an ultrasonic receiver ( 19 ) on the other hand. The sensors are arranged on opposite sides of the material web ( 12 ) in such a way that, if appropriate, focused ultrasonic waves are aimed specifically at the region of the tear-off strip ( 11 ). If a tear-off strip ( 11 ) is missing, an appropriate signal is generated by the ultrasonic receiver ( 19 ).