Patent ID: 7429291
Filing Date: 2008-09-30
Classification: B41M,C09D

Abstract:
1. A print ink comprising: a first fluorescent coloring material that emits a fluorescence at a predetermined fluorescence wavelength to be used for measurement or determination on excitation at a predetermined excitation wavelength of 254 nm; and a second fluorescent coloring material that emits a fluorescence on excitation at the predetermined excitation wavelength, wherein an excitation wavelength spectrum for obtaining the fluorescence at the predetermined fluorescence wavelength of the first fluorescent coloring material has a peak wavelength range next to the predetermined fluorescence wavelength, and an emission fluorescence spectrum of the second fluorescent coloring material has an emission wavelength region substantially including at least the peak wavelength range, wherein the first fluorescent coloring material and the second fluorescent coloring material each have an absorption wavelength in a visible light region, and wherein the amount of the second fluorescent coloring material in the print ink is more than the amount of the first fluorescent coloring material in the print ink.