Patent ID: 6513921
Filing Date: 2003-02-04
Classification: B41M,C09D

Abstract:
A method for producing an invisible printed image on a substrate and thereafter causing said printed image to fluoresce comprising:providing an ink delivery system comprising: a housing comprising at least one ink retaining chamber therein, said ink retaining chamber comprising a supply of an invisible ink composition therein, said ink composition comprising an invisible dye comprised of at least one uncompleted invisible metal phthalocyanine fluorophore which absorbs light within a wavelength range of about 650-715 nm and emits light within a wavelength range of about 670-720 nm, said ink composition further comprising an ink vehicle comprised of water and at least one organic solvent; and a printhead operatively connected to said ink retaining chamber in said housing, said printhead comprising at least one ink ejector for expelling said invisible ink composition on-demand from said ink retaining chamber; providing a substrate; activating said printhead of said ink delivery system in order to deliver said invisible ink composition from said ink retaining chamber onto said substrate; and applying light having a wavelength of about 650-715 nm to said invisible ink composition on said substrate, said applying of said light causing said ink composition to emit fluorescent light having a wavelength of about 670-720 nm.