Image analysis – Applications – Document or print quality inspection
Reexamination Certificate
1999-10-27
2002-04-16
Couso, Jose L. (Department: 2624)
Image analysis
Applications
Document or print quality inspection
C382S115000, C382S181000
Reexamination Certificate
active
06373965
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to systems for authenticating articles, methods for authenticating articles, and processes for marking articles for later authentication. This invention relates particularly to mechanisms and methods for detecting indicia which may include graphic images and/or characters and for comparing the detected indicia with predetermined indicia to verify the articles' authenticity if the detected indicia are recognized. This invention relates more particularly to detection, discrimination, and recognition of fluorescent indicia rendered detectable by illumination of articles with ultraviolet light.
BACKGROUND OF THE INVENTION
Problems Solved by the Invention
The counterfeiting of articles of many kinds has become a serious problem worldwide, causing great loss of revenues to legitimate businesses and to individuals. Counterfeiting has produced articles that are very difficult to distinguish from the genuine articles, taking sales revenues from the producers of genuine articles and impacting legitimate business' reputations when the counterfeit articles have inferior quality and/or non-existent manufacturers' support. Similarly, problems and losses occur due to counterfeiting of articles used for financial transactions or identification, such as credit cards, drivers' licenses, passports, and immigration documents. Even when genuine articles have been marked with authentication markings such as watermarks, special papers, and holograms which are difficult to replicate, counterfeiters have managed to produce articles that appear genuine. The general availability of newer replication technology such as high-resolution image scanners, laser copiers and printers, and color-accurate color copiers and printers has enabled counterfeiters to produce more credible counterfeit articles. These technological developments of replication hardware continue to make rapid progress, as do the computer hardware and software that support them. Thus it is useful to have additional ways to mark articles for authentication with greater security. Greater security may be achieved by making authentication markings more difficult for counterfeiters to detect and interpret, by incorporating greater complexity into the markings, and by making replication by counterfeiters more difficult. Combining multiple kinds of marking indicia can further increase the complexity of detection, interpretation, and replication, thus providing even better security. Considering the security issue from another point of view, it is not desirable to use the same means that generated the visible appearance of an article to authenticate it, as the visible appearance is becoming easier to replicate. Invisible indicia that cannot be reproduced by common visible graphic copying and printing means can provide improved security, especially when combined with complex images, patterns, and/or characters.
Notations and Nomenclature
In this specification, the following terms or abbreviations are used with the meanings listed here:
CCD—charge coupled device
DSP—digital signal processor
excitation time—a characteristic time for a fluorescent emission to be excited after ultraviolet illumination of a fluorescent substance begins
extinction time—a characteristic time for a fluorescent emission to decay exponentially from its initial emission intensity I
O
to intensity I
O
/e
IR—light in the infrared portion of the spectrum
OCR—optical character recognition
registration—the conventional definition of this term in the fields of graphic communication and printing, as defined, for example, in “Glossary of Graphic Communications” compiled by Pamela Groff and published by Graphic Arts Technical Foundation (Prentice-Hall, Inc., Upper Saddle River, N.J., 1998) at pages 245-246.
UV—light in the ultraviolet portion of the spectrum
visible/IR—light either entirely in the visible portion or entirely in the infrared portion, or partly in both visible and infrared portions of the spectrum
visible/UV—light either entirely in the visible portion or entirely in the ultraviolet portion, or partly in both visible and ultraviolet portions of the spectrum
DESCRIPTION OF THE RELATED ART
Many methods have been known to authenticate valuable articles. Some known methods include imprinting a white-light hologram or imprinting reflective and diffractive indicia which display distinctive images that are difficult to counterfeit. Other known methods include incorporation of distinctive fibers into the articles, such fibers being detectable by visual observation, microwave irradiation, or other means. U.S. Pat. No. 4,921,280 describes fibers made luminescent by a dyeing process employing rare-earth compounds, which fibers may be incorporated into articles requiring authentication.
It is known that documents may be authenticated by marking the documents with substances such as inks or dyes that appear invisible or relatively unnoticeable to the naked eye in ordinary visible illumination, but that fluoresce when illuminated with ultraviolet light, revealing marks that serve to identify the legitimate document. These methods depend on substances that are not easily or inexpensively identified by a counterfeiter, and not easily or inexpensively duplicated or mimicked by a counterfeiter. When using these methods, it is desirable to use substances such as dyes or inks that fluoresce in narrow spectral bands which are distinguishable by sufficiently narrow-band detectors, but not readily distinguishable by eye. In U.S. Pat. No. 4,146,792 by Stenzel et al., these methods are extended to include dyes containing rare-earth elements whose fluorescence is influenced by the chemical environment of the fluorescing atoms in a non-fluorescing matrix, and the detection is refined to include detection of predetermined fine structure in the line spectrum of emitted light. Yet another class of authentication methods uses substances which fluoresce in the infrared portion of the electromagnetic spectrum when illuminated by light in the visible portion of the spectrum.
In U.S. Pat. No. 4,642,526 by Hopkins and assigned to the assignee of the present invention, a source of ultraviolet light is made self-modulating at a predetermined frequency. Detection of the secondary radiation, filtering of the detected signal, and demodulation of the filtered signal at the predetermined frequency allow the system of Hopkins' invention to detect the fluorescent marks despite interference from ambient light sources.
Marking products with indicia such as bar codes using fluorescent substances such as inks or dyes is also known in the prior art, both for the purposes described above and for providing identification on the products without detracting from the products' appearance as normally viewed in visible light. U.S. Pat. No. 4,983,817 by Dolash et al. describes methods and apparatus for reading bar codes printed with fluorescent substances, while compensating for variations in background reflectance over the area printed with the bar code. U.S. Pat. No. 5,064,221 by Miehe et al. shows the use of fluorescent substances added to ink ribbon used for printing original documents, in order to distinguish the originals from copies. In many of the known authentication methods using fluorescence, the fluorescent identifying substance may be incorporated into the article during the article's manufacture. In U.S. Pat. No. 4,451,521 by Kaule et al., for example, luminophores are incorporated into paper during its manufacture. Some of the fluorescent substances used in the prior art for authentication purposes contain heavy metals, which are not as safe or environmentally benign as substances not containing such heavy metals. While fluorescent substances have been used in many ways in the prior art to mark articles with indicia for interpretation by human observers, to our knowledge neither optical character recognition (OCR) systems nor image verification systems have been combined with fluorescent markings and UV light illumination
Angstrom Technologies, Inc.
Couso Jose L.
Do Anh Hong
Touw Theodore R.
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