| 摘要 |
A document reader for optoelectronically illuminating, reading and interpreting (i.e. processing and analyzing) indicia appearing on a document in a machine readable zone thereof, wherein the indicia is made visible only under illumination by non-visible light (i.e. UV or IR). UV (or IR) light sources (LED's) of the reader are rapidly switched to a stable, peak UV (or IR) illumination frequency or frequency range to illuminate and render visible such covert UV-visible (or IR-visible) indicia. An optoelectronic image sensor (CCD) captures the document image, which includes the indicia rendered visible by the UV source illumination, and the covert indicia is identified from the captured image. An optical path, being folded by two mirrors so as to provide a compact geometry for the reader, extends between a reading surface on which the document is place and the image sensor. A lens configured for focussing light defining an image onto the sensor is provided in the optical path. The reader may also include bank(s) (array(s)) of visible light sources (LED's), for illuminating visible indicia, in addition to UV and IR LED arrays and any IR light sources may also be used for illuminating visible OCR characters according to ISO 1831. A controller is provided to sequentially activate each different light source bank.
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