| 摘要 |
An optical inspection system (10) for deriving information from an item (12) to be inspected includes a light source (14), an optical reader (16) responsive to the light reflected from the inspected item for deriving an analog signal (83) indicative of information sensed on the inspected item, a threshold circuit (24) for setting a dynamic threshold used to convert the analog signal into a binary signal (144) indicative of the information sensed on the inspected item. The threshold circuit includes a high peak detector (100) and a low peak detector (102) responsive, respectively, to the highest peak and to the lowest peak in said analog signal for generating a high and low signal, respectively, indicative thereof. A threshold setting circuit (132) is responsive to the high signal and the low signal to set a threshold therebetween. A comparator (22) compares the analog signal with the set threshold and converts the analog signal to a binary signal indicative of the information sensed on the inspected item. An indicator (26) is provided which is responsive to the high and low signals for generating a dynamic visual indication of the difference or contrast between the high and low signals and a visual indication of the light level.
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