INSPECTING METHOD OF PRINTED MATTER

摘要

PURPOSE:To improve inspection precision by decomposing the entire surface of the pattern of printed matter into plural picture elements and inputting a pattern signal, extracting picture elements whose print trouble detection signal exceeds a permissible value and edge parts of the pattern, and masking detection signals of corresponding picture elements. CONSTITUTION:A pattern signal of each picture element inputted from a detection part is stored in a reference memory 17 in reference signal fetch mode through an A/D converter 15. At the same time, a reference signal SSS is transferred to a difference circuit 16 to calculate a difference of each picture element from the signal SSS. At this time, the signal SSS is in the zero state and a difference inspection signal DIS becomes equal to the signal SSS. The signal DIS is delayed by several picture elements through a delay circuit 19 and a difference circuit 18 performs difference arithmetic to obtain a secondary difference signal DDS. A threshold circuit 20 extracts a picture element corresponding to the secondary difference signal DDS exceeding the permissible value as an edge part of the pattern and a CPU14 writes the edge extraction result of each picture element in a mask memory 30. Then, inspection as to pattern information inputted to a detection part 4 is carried out to improve the precision of the inspection.