| 摘要 |
PURPOSE:To remove influence caused by expansion and contraction of a printed matter, and to discriminate it with high accuracy, by detecting a start point and a terminal of a printed pattern when calculating the analogy of an AC portion of the printed matter, and deriving the first and second analogies starting from the start point and the terminal, respectively. CONSTITUTION:Printed matter 5-7 to be checked is irradiated by an illumination light source 5-1, and a reflected ray from a prescribed area 5-3 is detected by a photodetector 5-5. Also, a start point and a terminal of travelling printed mat ter 5-7 are detected by a photoelectric switch 5-8, and a printed matter end signal TO is outputted. An output of this photodetector 5-5 is sampled in accordance with a sampling signal from a timing control signal generating circuit for inputting the signal TO by an A/D converter 6-3, and both signals are converted to a digital signal, respectively. Subsequently, analogy in an AC portion against plural waveform signals to be a reference stored in advance, starting from each start point and terminal are derived by a microcomputer, etc., and the derived similarities are combined, by which printed matter is discriminated with high accuracy. |
