INSPECTION OF PRINTED MATTER

摘要

PURPOSE:To remove quickly the cause of a printing fault and to decrease paper loss by calculating differentially a scanned detection signal and a reference signal and discriminating the kind of the printing fault from the generating sequence of the rise and fall in the change part of the resulted signal and the time between the same. CONSTITUTION:A pulse appears at the upper limit threshold with a delay for specified time after generation of the pulse exceeding the lower limit threshold level as shown in the figure (a) in the case of water sagging or oil sagging. The lower limit threshold pulse appears conversely after generation of a pulse at the upper limit threshold as shown in the figure (b) in the case of ink staining. A pulse is generated on the opposite side in the state of having virtually no time delay after generation of a pulse at the threshold of either the upper or lower limit as shown in the figure (c) in the case of sticking. The king of the printing fault is thus discriminated from the two data; the sequence of the rising pulse and falling pulse appearing with one printing fault and the time between the two rising and falling pulses appearing with one printing fault.