Patent ID: 7438378

Claim:
A fluorescent indicium printing device for printing and detecting a black fluorescent indicium comprising: a print head configured to print the black fluorescent indicium using a black fluorescent ink, the ink including at least one black pigment and at least one fluorescent taggant; a first ink sensor located downstream from the print head for detecting the at least one fluorescent taggant in the printed black fluorescent indicium including: a first radiant energy source configured to radiate at a first excitation wavelength suitable for exciting the black fluorescent indicium; and a photodetector having a bandpass filter, wherein the photodetector is adapted to detect luminescent energy at a first excited luminescent wavelength from the black fluorescent indicium printed by the print head, a second ink sensor located downstream from the print head including an infrared detector for detecting the at least one black pigment in the black fluorescent indicium; and a controller for determining if the indicium comprises a particular black fluorescent ink based upon output of the first ink sensor and the second ink sensor.