Patent ID: 7116798

Claim:
A system for processing a card in the form of a fare card, keycard, airline boarding pass, I.D. card, passport and the like, said system positioned at a control point to determine passage or refusal of a card holder; said system including an automatic reader adapted to receive said card from a bearer, said reader including card intake and return, and further including a feeder mechanism defining a relative path of movement for said card from said intake to said return; a first image capture stage, located along said path generally adjacent said card reader, adapted to capture a first image of said card in the form of primary image data; a digitizer stage interconnected with said first image capture stage and adapted to receive said primary image data therefrom and to formulate a primary digitized image of said card; a heater unit positioned generally adjacent said first image capture stage along said path, and adapted to heat said card to a relatively high temperature such that any explosive trace substance present on said card will undergo an energetic reaction imparting a char smudge signature to said card; said card conveying mechanism adapted to move said card relatively with respect to said heater unit to a second image capture stage for capturing a secondary image of said card and char smudge signature in the form of secondary image data; said digitizer stage interconnected with said second image capture stage and adapted to receive said secondary image data therefrom and to formulate a secondary digitized image of said card; an image subtractor stage interconnected with said digitizer stage and adapted to receive said primary and secondary digitized images from said digitizer unit; said image subtractor stage further adapted to subtract said primary digitized image of said card from said secondary digitized image to obtain a digitized resultant image; a computer processor unit interconnected to said image subtractor stage and adapted to receive and analyze said digitized resultant image to determine the presence of a char smudge; said computer processor unit further adapted to transmit an output signal to said control point directing restraint of said card and bearer when char smudge signature is detected as present on said card, and directing passage permission when no char smudge is detected; whereby fare cards and the like presented for passage through a control point turnstile or gateway are automatically examined, the presence of any trace explosive substance is detected, and the card and card holder are permitted passage or restrained.