Details:
Summary:
In order to make observations on the print quality, the printer has to sample the latest paper from the conveyor line, take it to the evaluation table, and finally, begin the inspection sequence. Because of the manual operations required, the interval between successive visual inspections can easily take more than 500 impressions with many bad quality zones needing correction. If the pressman could find out the page quality at once after printing, he could make corrections faster and avoid excessive waste. An on-line quality monitoring device inspecting the webs printed could provide a solution to this problem. If the pressman could find out the page quality at once after printing, he could make corrections faster and avoid excessive waste. An on-line quality monitoring device inspecting the webs printed could provide a solution to this problem. This paper gives a progress report about an investigation to apply a CCD vector camera as a sensor for on-line monitoring and measuring the print quality. For this purpose, an experimental microcomputer system was assembled and programmed. By means of a real time image processing system COMTAL VISION ONE/20 the resolution demand (number of pixels needed) and the optimal amount of gray-scale steps needed were studied. Measuring problems, like timing, exposing, measuring speed and user interface problems have also been discussed in the paper. The research is in progress at the Graphic Arts Laboratory in the Technical Research Center of Finland. The goal is to develop a system for on-line monitoring, measuring, and recording of the quality of newspaper printing.