Apparatus for monitoring reproduction quality of printed sheets

摘要

An apparatus for monitoring the quality of reproduction of printed material employs a detector unit (B) incorporating a line-scanning camera (3) and the paired light sources (1,2) compensated for printing speed which uniformly illuminate the surface (5) of the printed sheet on the drum (A'). The A/D converted image data obtained by the scanning and time averaging of successive sheets is compared with similar data previously obtained and stored as a quality reference. In the event of a disparity in excess of a given threshold being detected a further assessment and comparison is undertaken and if an abnormality is then confirmed the sheet is separated for exclusion.