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US 5,525,798 AGranted
Bar code scanner for reading a lower layer luminescent invisible ink that is printed below a upper layer luminescent invisible ink
AssigneePitney Bowes Inc.
InventorsWilliam Berson, Judith D. Auslander
Life of this patent
Estimating the term…
Abstract
Inks have been discovered that are selectively excitable by different wavelengths of incident radiation. This allows a lower layer bar code to be written on an object with an invisible ink and an upper layer bar code to be written over the lower layer bar code with an ink that is invisible to the naked eye. The apparatus of this invention is a detector that is able to read the upper and lower layer bar codes.
Claims8
A system for sequentially reading indicia, said system comprises:
- means for reading a first indicia that is printed on an object with a first luminescent ink that is invisible to the human eye;
- means for reading a second indicia that is placed on top of the first indicia, said second indicia, is similar in appearance to said first indicia but differs from said first indicia, said second indicia is made of a second luminescent ink that is invisible to the human eye;
- and
- means for switching from said first reading means to said second reading means so that said first and second indicia or a portion of said first and second indicia appear to a human observer viewing said first and second indicia to move.
1 more element
Dependencies are inferred from the claim text.