High speed web printing inspection with multiple linear cameras

Abstract

Purpose: To detect the defects during the high speed process of web printing, such as smudges, doctor streaks, pin holes, character misprints, foreign matters, hazing, wrinkles, etc., which are the main infecting factors to the quality of printing presswork. Methods: A set of novel machine vision system is used to detect the defects. This system consists of distributed data processing with multiple linear cameras, effective anti-blooming illumination design and fast image processing algorithm with blob searching. Also, pattern matching adapted to paper tension and snake-moving are emphasized. Results: Experimental results verify the speed, reliability and accuracy of the proposed system, by which most of the main defects are inspected at real time under the speed of 300 m/min. Conclusions: High speed quality inspection of large-size web requires multiple linear cameras to construct distributed data processing system. Also material characters of the printings should also be stressed to design proper optical structure, so that tiny web defects can be inspected with variably angles of illumination.

Research of Picture Adaptive Processing for Packaging Printing Online Detection

“…Because the way of data collection in color liner CCD is single collection, it divides the whole image into multiple single lines which parallel to the direction of CCD acquisition. The single data gathered by the color liner CCD is related to the hardware parameters of resolution, this determine that the data quantity is fixed value [1]. When the speed of printing is slow, the data position of the single line in manuscript corresponds to the scanning image.…”

“…At present, using machine vision technology to replace the traditional manual in printing quality detection has become the trend. Printing quality online detection system uses the CCD to scan the prints under the standard light and obtain the digital image, also, computer analysis and process the digital image to judge the quality of the print [1]. However, in the process of the scanning, there is a situation that the speed of scanning and print speed can't be matched.…”