| 摘要 |
<p>The known quality inspection method for a printed matter of the type that a print pattern on the printed matter is optically imaged on photo-sensitive elements and a print depth of the printed matter is detected by taking out intensities of light inciding to the respective photo-sensitive elements as electrical quantities, is improved. The improvements reside in that from momentary changing detection signals obtained by optically scanning a traveling printed matter, detection signals generated in a particular area are extracted to be used as a reference signal, and anomalies occurred in the printed matter are detected by comparing the momentarily changing detection signals with the reference signal. Preferably, the particular area or a non-pattern area is an unprinted area, and detection signals generated from a printed area are compared with the reference signal. More preferably, detection signals generated from a non-pattern area are compared with the reference signal. In a modified embodiment, detection signals obtained by optically scanning print depth variations in an ink key width unit of the printed matter are compared with detection signals from a normal printed matter which were preliminarily detected through a similar method and stored for use as a reference signal. <IMAGE></p> |
