| 摘要 |
An optical sensor system for validating documents transports a document under test between a light source and an optical interface circuit. A photodetector within the optical interface circuit generates an electrical current signal at its output based on the amount of detected light transmitted through and/or reflected by the document. A photodetector interface circuit is connected to the photodetector output and converts the current signal to a signal indicative of the detected light without undesirable electrical offsets, such as manufacturing, production and temperature offsets. In particular embodiments, the current signal is further processed to take advantage of the dynamic range of an associated analog converter.
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