Registering and controlling quality of printed product - evaluating over spectral range of 400 to 700 nanometres and evaluating individual colours upon detection of fault

摘要

In a prim. phase a faulty sheet is detected by a first spectral channel operating over the complete spectral range of 400 to 700 nm for uniform evaluation. When a fault (4) is detected by a rise in signal level (A"), the three other spectral channels are applied for evaluation of the separatee colours. The coordinates of the fault location are delivered to an image analysing and expert system computer. After a set number of fault examples in a sec. phase, the actual images are transferred to the image analysing computer in pixel format. The fault type and preventive measures to be taken are derived from the expert system computer. USE/ADVANTAGE - Rapid measuring for ascertaining cause of printing faults and simple associated correction.