Electromechanical rotogravure stylus automatic calibrator

摘要

In an electromechanical engraving system, rotogravure calibrating apparatus automatically adjusting the engraving operation of an engraving-head stylus of the system in real time by calibrating a stylus-actuating engraving signal according to a calibration factor relating printed image density to engraved cell depth for a designated engraving screen ruling corresponding to printed image resolution. The calibrating apparatus includes a cell observation and measuring device which obtains data for calculating cell size by imaging the form of individual test cells engraved by the stylus into the surface of a rotogravure printing cylinder, and an engraving signal calibrator which adjusts engraving signal control parameters according to the cell size calculation and to the calibration factor. The engraving signal calibrator derives an image-density/cell-depth reference characteristic computed according to cell size data from cells engraved to correspond to a representative series of test image densities at the designated screen ruling, and computes the calibration factor as a correction of the image-density/cell-depth reference characteristic, generating engraving signal gain data which accordingly adjust the engraving signal actuating the stylus. The engraving signal is rapidly and automatically adjusted through a simplified calibration of the stylus-actuating engraving signal, stabilizing stylus lateral displacement adjustments for consistency among printing operations.