| 摘要 |
An optical system for detecting printing flaws on a printed sheet includes a plurality of detector arrays each with a plurality of detector elements positioned to scan a reference sheet and the test sheet. Each detector element in each array "sees" a small area of a test or a reference sheet as the sheets are scanned and the output of the detector elements are synchronized with each other and compared. When the output from the test array detector does not equal the output of the corresponding reference array detector and the system is synchronized, the system coupled thereto indicates that the two areas "seen" are unequal. A sufficient and pre-set number of unequal indications are required to decide whether the test sheet is sufficiently different from the reference sheet that it should be destroyed.
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