INSPECTION OF PRINTED MATTER

Japanese Patent JPH01163067

A

PURPOSE:To enhance accuracy of inspection of peripheral areas of a pattern, light scumming, longitudinal streaks or the like, by setting a reference value for each pixel, and discriminating abnormality of a printed matter based on a differential signal of pixels in adjacent equivalent patterns in excess of the reference value and on signals detected by dividing the pattern into the pixels. CONSTITUTION:A printed matter 2 carrying patterns 1 is detected by dividing into pixels by a line sensor 3, and on the basis of each pixel in adjacent equivalent patterns, the detected members are subjected to subtraction by a calculating circuit 4 to obtain differential signals. The differential signals for each pixel are stored in a reference value forming part 6, and reference signals formed based on the one-sheet amount of the differential signals. Next, the same operation is conducted also for a printed matter 2 newly supplied, and the reference values are updated. When abnormal printing or the like is present, the differential signals for the adjacent equivalent pattern on the printed matter exceed successively the upper or lower limit of the reference values or the excess values are not less than a predetermined value. On the other hand, when slippage or the like is present, the differential values are discontinuous or the excess values are not more than a predetermined value. Based on such a phenomenon, the abnormal printing and slippage are discriminated.

OKA KEIICHI
SUZUKI SHINICHI
NAKAMURA HIROYUKI
YOSHIDA KIYOTAKA

JP32142587A

June 27, 1989

December 21, 1987

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OOKURASHO INSATSU KYOKUCHO

G01N21/88; B41F33/04; B41F33/14; G01N21/89; G01N21/892; G01N21/93; G01N21/94; G06T1/00; H04N1/00; (IPC1-7): B41F33/04; G01N21/88; G01N21/89; G06F15/62; H04N1/00

JPS60190360A

1985-09-27

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