METHOD AND DEVICE FOR ACCURATELY POSITIONING MARK ON BAND-SHAPED MATERIAL CUT PIECE

摘要

Successive watermarks on a running web of coherent paper sheets are monitored by a scanner which generates defect signals in response to detection of watermarks outside of selected portions of the respective sheets, and the cross cutter which severs the web to form discrete sheets is then adjusted to separate the respective sheets from the next-following sheets with a delay or prematurely so that the sheets bearing the improperly positioned watermarks are too short or too long. Such defective sheets are segregated from satisfactory sheets downstream of the cross cutter in properly delayed response to generation of defect signals by the scanner.