Variable printing system and method with optical feedback

Abstract

A method and system for verifying the intended imaging produced by a printer allow this task to be accomplished in essentially real-time, and utilizing relatively inexpensive, and high speed (e.g. about 200 feet per minute or greater) components. A computer control commands a raster image processor (RIP) to generate electronic print data (e.g. a bitmap) that is sent to an electronic digital printer (such as an inkjet cartridge array) and also to a print monitor. The printer images the bitmap onto a web or sheet, then a linear digital photosensor (e.g. photodiode) array scans essentially every pixel across the width of the web or sheet image area and transmits the scanned data to the print monitor system, which compares it to the bitmap produced by the RIP. If there is some discrepancy (of any sort), a message is generated which is ultimately transmitted back to the computer control where it may be used to log defective documents (MAG) being produced, generate human recognizable indicia (such as a warning light or sound), or shut down the system components. A second linear photodiode array may be provided before the printer and the data from it sent to the print monitor system to be combined with the electronic bitmap and compared to the data from the first sensor to determine whether there is any deficiency.