Switchon-switchoff, multistate, interactive, antiphotocopying antifraud and antifaxing system
First Claim
1. A method of preventing reproduction of printed matter on a substrate by photocopying and telefaxing wherein an intense amount of light is used, comprising the steps of:
- providing a substrate with at least one surface;
applying a photochromic dye to the at least one surface, wherein the dye changes color in response to exposure to light with a response time which is a function of the amount of light absorbed by the dye in a given time period;
illuminating the at least one surface with an intense amount of light; and
applying an optical element to at least one of the dye and the at least one surface to decrease the response time of the dye and accelerate the change in color of the dye, wherein the optical element increases the proportion of the intense amount of light which is absorbed by the dye.
1 Assignment
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Accused Products
Abstract
A method and apparatus for preventing reproduction of printed matter on a substrate by photocopying, telefaxing and the like. A substrate is provided with at least one main surface and a photochromic dye is applied to the one main surface, wherein the dye changes color in response to exposure to light with a response time which is a function of the amount of light absorbed by the dye in a given time period. The one main surface is illuminated with a given amount of light and the response time is decreased to accelerate the change in color of the dye by increasing the proportion of light which is absorbed by the dye from the given amount of light.
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Citations
10 Claims
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1. A method of preventing reproduction of printed matter on a substrate by photocopying and telefaxing wherein an intense amount of light is used, comprising the steps of:
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providing a substrate with at least one surface; applying a photochromic dye to the at least one surface, wherein the dye changes color in response to exposure to light with a response time which is a function of the amount of light absorbed by the dye in a given time period; illuminating the at least one surface with an intense amount of light; and applying an optical element to at least one of the dye and the at least one surface to decrease the response time of the dye and accelerate the change in color of the dye, wherein the optical element increases the proportion of the intense amount of light which is absorbed by the dye. - View Dependent Claims (2, 3, 4, 5)
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6. A substrate for preventing reproduction of printed matter thereon by photocopying and telefaxing with an intense amount of light, comprising:
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at least one surface; a photochromic dye applied to the at least one surface, wherein the dye changes color in response to exposure to light with a response time which is a function of the amount of light absorbed by the dye in a given time period; and an optical element applied to at least one of the photochromic dye and the at least one surface and increasing the proportion of light from an illumination by an intense amount of light which is absorbed by the dye to decrease the response time of the dye in response to the illumination of the at least one surface with the intense amount of light to accelerate the change in color of the dye and thereby prevent reproduction of information on the at least one surface. - View Dependent Claims (7, 8, 9, 10)
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Specification