| 摘要 |
PURPOSE:To detect a surface defect satisfactorily with a simplified low-cost circuitry, by storing and holding binary-coded signals as multiple division lane signals into a shift register for each digit. CONSTITUTION:A detection light scans lanes set on a web not illustrated and the reflected light thereof is fed to a light receiving section 12 to convert the presence of a defect into a binary codes signal. The binary-coded signal is synchronized with a division signal from a lane division signal generation circuit 20 and inputted into a binary adder 14 through a latch circuit 13 to be stored and held into shift registers 15a-15d. In this manner, defect signals are added up for each lane to be held into the shift registers 15, the operation which is performed sequentially for data cells with a specified length in the web. A frequency division circuit 18 into which a length measuring pulse is inputted sends a scanning end signal to the binary adder 14 when the specified length set with a setting circuit 19 is reached. At the same time, outputs of the shift registers 15 are supplied to a digital comparator 16 and compared with a reference value to judge a defect.
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