Use of fluorescent inks for document authentication
First Claim
1. A method for introducing a print characteristic in a visible image printed on paper, comprising printing a part of the image with an ink having first and second components, the first component being less fast than the second component in response to an applied activator, and the first component being a fluorescent component having its fluorescence substantially masked in the presence of the second component in the absence of the applied activator, and applying the activator to stimulate a bleed of the first component beyond the area of said part to create a unmasked area of the fluorescent component at the area of the bleed.
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Accused Products
Abstract
In a method for introducing an authentication print characteristic in a visible image printed on paper, a part of the image is printed with an ink having first and second component dyes. The first component is less fast than the second component in response to an applied activator. The first component is normally masked by the second component but applying an activator stimulates a bleed of the first component beyond the area of the image part to create a predetermined unmasked area of the fluorescent component. The invention extends to paper on which the authentication print characteristic has been printed and to a method of detecting a forged image by analyzing paper to detect such an image bleed.
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Citations
28 Claims
- 1. A method for introducing a print characteristic in a visible image printed on paper, comprising printing a part of the image with an ink having first and second components, the first component being less fast than the second component in response to an applied activator, and the first component being a fluorescent component having its fluorescence substantially masked in the presence of the second component in the absence of the applied activator, and applying the activator to stimulate a bleed of the first component beyond the area of said part to create a unmasked area of the fluorescent component at the area of the bleed.
- 15. A method of determining whether a forged image is present on paper comprising using black light to examine the paper to determine whether a fluorescent print characteristic is present in the image, the print characteristic, if the image is not a forgery, contained in a part of the image printed with an ink having first and second components, the first component being less fast than the second component in response to an applied activator, and the first component being a fluorescent component having its fluorescence substantially masked in the presence of the second component, an activator having previously been applied to stimulate a bleed of the first component beyond the area of said part to create the print characteristic as an unmasked area of the fluorescent component in the area of the bleed, the fluorescent print characteristic, if the image is a forgery, not being present in the image.
- 17. Paper bearing an authentication print characteristic in a visible image printed on the paper, a part of the image being printed with an ink having first and second components, the first component being less fast than the second component in response to an applied activator, and the first component being a fluorescent component having its fluorescence substantially masked in the presence of the second component, an activator having been applied to stimulate a predetermined bleed of the first component beyond the area of said part to create an unmasked area of the fluorescent component in the area of the bleed.
Specification