Performance of an On-Line Closed-Loop Color Control System

With the advent of on-line closed-loop color control devices, there are high expectations on the performance of such systems. Printers expect and manufacturers claim an elimination of drift, or long-term variation and a reduction in short-term variation, or noise in the process of maintaining solid ink density on a web offset press. Additionally, these systems claim to automatically drive the press during makeready to programmed target densities. This paper will show the results of such a system and its performance on these issues in a real-life printing environment and contrast the system to an open-loop approach, both in a hands-off mode and with operator intervention. Results will be quantified and conclusions will be drawn.