Verfahren zur zeilenweisen Herstellung von zylindrischen Rasterdruckformen

摘要

Method and apparatus for controlling the scanning and engraving heads associated respectively with a rotating cylinder having a master pattern thereon and a rotating cylinder on which a half-tone screen printing form pattern of the master is to be produced. The control is such that the heads are intermittently stepped so that the scanning and engraving paths each are in the form of a series of axially spaced incomplete circumferential lines with the end of each such line being joined to the beginning of the next line by a short helical line. Preparation for the subsequent generation of a control signal to stop engraving is effected in response to stepping movement of the heads and the actual stop signal is generated after the stepping movement so that engraving will always actually stop at some point along the next circumferential line while neither head is moving. Thereafter, further stepping of the engraving head is suspended until the engraving is to be restarted so that the engraving head "idles" along the path on which engraving ceased. The signal to restart engraving is timed to occur immediately prior to the point at which the stop engraving signal occurred so that there is always the slight overlap between stop and restart, and no non-engraved gaps occur between stop and restart.