Patent ID: 6969549

Claim:
A machine-readable indicia-bearing substrate structure, comprising: a substrate having a first surface and a second surface; a first information bearing indicia defined by a fluorescent material positioned adjacent to the first surface; a second information bearing indicia defined by a fluorescent material positioned adjacent to the second surface; and means for preventing interference between a first fluorescing signal emitted by the first indicia and a second fluorescing signal emitted by the second indicia during a detection process for reading information from said first indicia or said second indicia, in which detection process the substrate structure is illuminated by illumination energy of a predetermined wavelength or wavelength range which causes said fluorescent material to fluoresce, said means including a reflective layer structure positioned between the first indicia and the second indicia, said reflective layer structure having sufficient thickness and opaqueness to prevent passage therethrough of said first fluorescing signal and said second fluorescing signal and to reflect said illumination energy; wherein the substrate is a print medium, and the indicia are applied to a portion of the print medium which does not receive printed components of an image during a printing process; and wherein the substrate comprises first and second thin layers of a substrate material, and said reflective layer structure includes a reflective layer sandwiched between the first thin layer and the second thin layer.