Method for digital printing on a running printing-material web
A method for digital printing on a running printing material web ( 10 ), wherein repeating motifs (a, b, c) are continually printed on the web and images of the printed motifs are continually recorded with a camera and rendered as still images (a, b, g) on a display ( 14 ) for web observation, with the motifs displayed next to one another in a plurality of tracks (A, B, C) and with a repeat that changes from track to track, and in that the images for web observation are recorded track by track and synchronously with the repeat applicable to the respective track.
1 . A method for digital printing on a running printing material web, comprising the steps of:
continually printing repeating motifs on the web by the step of displaying the motifs next to one another in a plurality of tracks and with a repeat that changes from track to track;
continually recording images of the printed motifs with a camera; and
rendering the recorded images as still images on a display for web observation by the step of recording the images for web observation track by track and synchronously with the repeat applicable to the respective track.
2 . The method according to claim 1 , wherein the step of continually recording includes the step of recording the images for web observation with at least one matrix camera.
3 . The method according to claim 2 , wherein the step of continually recording includes the step of providing a separate said matrix camera for each track, each camera being synchronized with the repeat applicable to the respective track.
4 . The method according to claim 2 , further comprising the steps of:
transversely moving the at least one matrix camera across the width of the printing material web, and
when the camera moves from one track to another track, switching the synchronization to the repeat for the another track.
5 . The method according to claim 1 ,
wherein the step of continually recording includes the step of recording the images for web observation with a line camera and
further comprising the step of branching off the image data for the still images from an image data stream supplied by the line camera track by track and synchronously with the respective repeat.
6 . The method according to claim 5 , further comprising the steps of:
buffering the image data supplied by the line camera in a buffer, wherein the buffer is divided into individually addressable memory blocks, each of which corresponds to a track to the printing material web,
reading the image data for the still images track by track from the buffer, and
compressing the read image data.
7 . A web observation system for a digital printing press for carrying out the method according to claim 1 , comprising:
at least one camera for recording images of the motifs which were printed in the various tracks on the printing material web, and
a synchronization device for track-by-track synchronization of at least one camera with the repeat of the printed motifs.