WO2000077104A1 - Serie de composants d'encre et composition d'encre utilisee pour des procedes relatifs a des documents de securite et produit de fabrication - Google Patents

Serie de composants d'encre et composition d'encre utilisee pour des procedes relatifs a des documents de securite et produit de fabrication Download PDF

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Publication number
WO2000077104A1
WO2000077104A1 PCT/US2000/015824 US0015824W WO0077104A1 WO 2000077104 A1 WO2000077104 A1 WO 2000077104A1 US 0015824 W US0015824 W US 0015824W WO 0077104 A1 WO0077104 A1 WO 0077104A1
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WO
WIPO (PCT)
Prior art keywords
ink
ink composition
different
spectral response
ink components
Prior art date
Application number
PCT/US2000/015824
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English (en)
Inventor
Eric R. Lee
Martin L. Perl
Original Assignee
The Board Of Trustees Of The Leland Stanford Junior University
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Publication date
Application filed by The Board Of Trustees Of The Leland Stanford Junior University filed Critical The Board Of Trustees Of The Leland Stanford Junior University
Publication of WO2000077104A1 publication Critical patent/WO2000077104A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/0023—Digital printing methods characterised by the inks used
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M3/00—Printing processes to produce particular kinds of printed work, e.g. patterns
    • B41M3/14—Security printing
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
    • C09B67/00—Influencing the physical, e.g. the dyeing or printing properties of dyestuffs without chemical reactions, e.g. by treating with solvents grinding or grinding assistants, coating of pigments or dyes; Process features in the making of dyestuff preparations; Dyestuff preparations of a special physical nature, e.g. tablets, films
    • C09B67/0033—Blends of pigments; Mixtured crystals; Solid solutions
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D11/00—Inks
    • C09D11/30—Inkjet printing inks
    • C09D11/40—Ink-sets specially adapted for multi-colour inkjet printing
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D11/00—Inks
    • C09D11/50—Sympathetic, colour changing or similar inks
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/2823—Imaging spectrometer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M3/00—Printing processes to produce particular kinds of printed work, e.g. patterns
    • B41M3/14—Security printing
    • B41M3/142—Security printing using chemical colour-formers or chemical reactions, e.g. leuco-dye/acid, photochromes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M3/00—Printing processes to produce particular kinds of printed work, e.g. patterns
    • B41M3/14—Security printing
    • B41M3/144—Security printing using fluorescent, luminescent or iridescent effects
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
    • B41M5/52—Macromolecular coatings
    • B41M5/5218—Macromolecular coatings characterised by inorganic additives, e.g. pigments, clays
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
    • B41M5/52—Macromolecular coatings
    • B41M5/5227—Macromolecular coatings characterised by organic non-macromolecular additives, e.g. UV-absorbers, plasticisers, surfactants
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/2803—Investigating the spectrum using photoelectric array detector
    • G01J2003/2806—Array and filter array
    • G01J2003/2809—Array and correcting filter
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/2823—Imaging spectrometer
    • G01J2003/2826—Multispectral imaging, e.g. filter imaging

Definitions

  • the present invention relates to processes for authenticating objects, ink sets and ink compositions used in such processes, and objects formed using such ink sets and ink compositions.
  • the present invention also relates to an ink which can be used for labeling an object (for example, a document or other object) with identifying markings which can be rapidly verified as authentic and which are highly resistant to counterfeiting.
  • the present invention relates to inks, for security documents, which can be used with low cost and available (“off-the-shelf") technology for hardware, for verifying authenticity, and to methods of printing using such inks and methods of verifying authentication of objects containing markings of such inks.
  • Such techniques include use of optical variable devices, such as holograms, embossed diffraction gratings, thin film interference coatings, laser images, etc.; special inks including ultraviolet, fluorescent, infrared, liquid crystal, magnetic, photochromic, thermochromic, optically variable, metallic and thermochromic color shifting inks, etc.; special substrates such as security papers, metallic threads, watermarks, embedded security strips, etc.; and exotic printing techniques such as laser engraving, intaglio printing, microprinting, continuous color shift printing, spatially periodic printed structures, see- through patterns (dual-sided printing) , screen-angle modulation for periodic structure, etc.
  • optical variable devices such as holograms, embossed diffraction gratings, thin film interference coatings, laser images, etc.
  • special inks including ultraviolet, fluorescent, infrared, liquid crystal, magnetic, photochromic, thermochromic, optically variable, metallic and thermochromic color shifting inks, etc.
  • special substrates such as security papers,
  • Some of the techniques include embedded magnetic strips, magnetic inks, periodic printed patterns that produce a Moire pattern when viewed by electronic vision equipment, and recently data embedded in high resolution embossed patterns similar in format to CDROMs .
  • Embedded silicon chips are not physically useable for most paper-based documents.
  • Optical card technology is suitable for mechanically stiff protected objects such as credit cards that can be fed into appropriate readers, but like smart chips is not physically compatible with the majority of documents requiring forgery protection.
  • Printed bar codes are vulnerable to being duplicated by inkjet printers.
  • U.S. Patent No. 3,928,226 to McDonough, et al discloses an ink composition which can be provided for machine-readable tickets, tags, labels, postal imprints and the like, having (1) a visible color, that is, a color under ordinary mixed light frequencies, and (2) a fluorescent radiation color which, when irradiated with ultraviolet life, for example, fluoresces preferably in the red wavelength of about 5800A to 6200A.
  • the ink imprint may be read visually and then read by a fluorescent machine reader which is set to pick up the fluorescent wavelength of the ink.
  • this technique checks two different properties of a same ink.
  • U.S. Patent No. 5,289,527 to Ligas, et al discloses a method for authenticating articles, using a mixture of at least two photochromic compounds, the activated spectra having different absorption maxima.
  • This patent discloses that by using combinations of photochromic compounds having instrumentally identifiable different activated spectra and preferably also other identifiable different photochromic properties, a verifying instrument can be used to identify the individual photochromic compounds used in the display data and thereby authenticate the article.
  • This patent also discloses that basing authentication on different activated spectra and other defined characteristic photochromic properties of at least two photochromic compounds enables a large number of combinations and permutations which may be used to authenticate an article, increasing substantially the difficulty of copying the total system and thereby facilitating identification of counterfeit articles.
  • the spectral responses of the mixture of components containing the plurality of pigments and/or dyes are linearly additive (e.g., linear mixing of the spectra, or linearly additively combining of the spectral responses) .
  • a first pigment gives the fluorescent spectrum 1
  • a second pigment gives the fluorescent spectrum 3 shown in
  • Fig. lb If there is one-half as much of the first pigment as compared to the second pigment in a mixture formed from the first and second pigments, then the total fluorescent spectrum of the mixture will be that shown in Fig. lc, having intensities 5 and 7, where the spectral response of the mixture is a linearly additive combining of the spectral responses of each pigment. If there is one-tenth as much of the first pigment as compared to the second pigment in the mixture, then such mixture will have a total fluorescent spectrum as shown in Fig. Id with intensity maxima 9 and 11, where the spectra of the two pigments are linearly additive.
  • Linear mixing can provide a great variety of spectral patterns; however, where a well-equipped and determined counterfeiter has acquired knowledge of the set of inks used on a particular document, and also has a reader for reading such documents, by measuring the spectrum of a marking (e.g., dot) and knowing the set of inks used to print the marking the counterfeiter in a few trials can determine the mix the pigments used to make the marking and can reproduce the desired spectrum of the marking, and can thereby provide what appears to be an authentic document which in fact is a counterfeit. While, with many markings using different mixtures of inks, it becomes a tedious task to determine the compositions of the markings, if the set of inks used on a particular document is known such task becomes much easier using a computer.
  • a marking e.g., dot
  • a counterfeiter could use the reader to obtain separate spectra of each ink component, and then use equations of linear mixing in a computer to determine the linearly mixed ink composition of each marking.
  • special, secure ink sets will greatly inhibit the ability to provide a counterfeit
  • special, secure ink sets are usually expensive, detracting from linear mixing as a technique for avoiding counterfeiting.
  • limited distribution ink sets as an anti-counterfeiting measure is also vulnerable to compromise by theft and unauthorized sales, and diversion or theft of such ink sets can potentially compromise thousands of protected items.
  • the marking has a spectral response which deviates from a predicted linearly additive spectral response, the prediction being formed by adding the spectral responses of the ink components which form the ink composition making the marking.
  • a "trap-door” printing function can be used in order to hinder a counterfeiter.
  • a "trap-door” printing function one in which it is easy and cheap to print a, e.g., security label, but in which the printing technology makes it hard and expensive to figure out how to duplicate it
  • a "trap-door” printing function is implemented for the purposes of the present invention. Because of the difficulty of determining the proportions of each ink component used to form the ink making each dot (due, e.g., to the non-linearity of the spectral response of the ink making each dot, relative to spectral responses of these ink components), from the dot itself, a counterfeiter has to expend orders of magnitude more effort to duplicate the label than does the legitimate printer, rather than having to merely match the resources of the person printing the original label .
  • security is implemented not by making critical components expensive or available only through restricted channels, but by securing a data key which contains the information about which inks were used to form each of the markings and in what proportion they were mixed for each marking; the basis to avoid counterfeiting is not expensive and restricted, e.g., inks, substrates, etc., but rather is a data key which indicates the ink components, and it is much more feasible keeping the data key from a counterfeiter.
  • the data key is the information necessary to reproduce the original security label.
  • this data key may consist of a multimegabyte data file containing the mixture ratios for each individual dot giving each ink color used and in what proportions for that particular security label.
  • the data key for the same size array could be a password or pass phase for a security label with mixture ratios determined by a seeded software-based, random number generator.
  • Non- linear mixing or combining of pigment spectra, or a spectral response of a mixture which deviates from a predicted linearly additive spectral response of the individual spectral responses of the components of the mixture is a known phenomenon.
  • Such non-linear mixing can be shown in connection with Figs. 2a-2c.
  • a first pigment when used by itself, has the fluorescent spectrum shown in Fig. 2a, with intensity maxima at curves 21 and 23.
  • another ink in a set contains a second pigment, that is itself not fluorescent but which changes the spectra of pigment 1; for example, .01 parts of the second pigment when mixed with the first pigment changes the spectrum of the first pigment as shown in Fig. 2b, having intensity maxima of curves 17 and 19.
  • the part of the first pigment spectrum 21 in wavelength segment 2 (350- 400nm) is not effected by the presence of the second pigment, but the 0.01 part of the second pigment reduces by 80% the strength of the spectrum of the first pigment that lies in the 5-8 wavelength segments (curve 19) .
  • a counterfeiter who has a reader and who has the ink containing the first pigment and the ink containing the second pigment will still have to carry out a large number of trials in order to find the mixture that produces the spectrum in Fig. 2b.
  • this difficulty would further increase where there are more than two inks in the set of inks.
  • a third ink contained a third pigment, not in itself fluorescent but capable of enhancing the strength of the short wavelength part of the spectrum of the first pigment. Then the mixture of the three pigments would produce the spectrum in Fig. 2c, including increased intensity as shown by curve 22. This, of course, adds enormous to the difficulty of counterfeiting a pattern.
  • the present invention provides a set of ink components for providing ink compositions to form markings of an object, the set including a plurality of different ink components having respective spectral responses, whereby at least two of the different ink components can be mixed together to provide an ink composition, such ink components, when mixed together, providing a spectral response of the mixture which deviates from a predicted spectral response when linearly additively combining the respective spectral responses of the at least two of the different ink components.
  • an ink composition comprising a mixture of at least two ink components having respective spectral responses, wherein the spectral response of the mixture deviates from a predicted spectral response when linearly additively combining the respective spectral responses of the ink components of the mixture. While each of the two ink components can have a color, it is also possible that at least one of the ink components does not have a color by itself, but affects the spectral response of another ink component when the components are mixed.
  • the ink composition can be applied to an object, whereby authenticity of the object can be determined.
  • the object can include a plurality of the markings, and each marking can be a microdot, in order to increase difficulty of counterfeiting the markings (i.e., the object) .
  • each of the markings is a microdot, and each microdot preferably can be substantially invisible to the human eye.
  • Use of the marking as a microdot limits amount of material of the ink composition in the marking, further increasing difficulty in counterfeiting the marking (that is, increasing the difficulty in determining components of the ink forming the mark due to these being only a small amount of the ink) .
  • the object can include two (or more) markings respectively of different inks having different spectral responses; and wherein at least one of the first and second spectral responses has an effect on the other such that spectral response of at least one of the first and second markings differs from the first or second spectral response of the respective inks.
  • the object includes a substrate with at least one marking thereon; and the ink of the marking interacts with the substrate such that the spectral response of the marking is different from the spectral response of the ink.
  • the ink composition is applied to a substrate, e.g., to form a marking on the substrate.
  • the ink composition is an inkjet composition, with the composition being applied to the substrate by an inkjet printer (e.g., a standard inkjet printer) . Accordingly, convenient and inexpensive hardware can be utilized for forming the markings on the object, to provide an object which can easily be authenticated.
  • the printing method further includes selecting at least two of the plurality of different ink components of the set of ink components as previously discussed, with a mixture of these ink components being applied to a substrate as a marking. Moreover, additional selections of at least two of the plurality of different ink components of the set can be performed, to provide markings (e.g., microdots) having different spectral responses, further complicating the ability to counterfeit the markings.
  • markings e.g., microdots
  • a matching template is made which indicates authentic markings on the substrate of the object; through use of such template, verification of authenticity of the markings on the object can easily and rapidly be performed.
  • the matching template is the information that exists on, e.g., a verification computer which is compared with the information measured from the, e.g., security label in question to determine whether the security label in question is genuine. Due to the nonadditive color mixing (non- linearly additive color combining) , the matching template cannot practically be determined calculationally from the data key, but can be generated by printing and then taking measurements of the resultant printed security label. Conversely due to the nonadditive color mixing, the data key cannot be derived computationally given the matching template. This is the essence of the one-way function. Such one-way function is particularly effective where the nonadditive color mixing is strong.
  • the original printer prints the label using the mixtures at each point as defined by the printer's personal data key and then takes multispectral measurements of the label to make the matching template for that label.
  • anyone with the printing hardware and the data key can generate a matching template at will by printing out a label using the data key to define the mixtures and then taking measurements of the spectral characteristics of the resultant printed security label. If one possesses only the printed label without possessing the data key one is always free to make a matching template; however, one cannot replicate the label since that would require obtaining the data key or its equivalent from the matching template, which with a properly designed inkset and printer should be an intractably hard task.
  • the matching template for the purpose of this invention is a multi-spectral contour map made from the measured relative intensities of each area of the security array at each characterized wavelength. For a microdot-based array this is the contour map made from the measured relative intensity at each wavelength of each microdot relative to its neighbors.
  • the matching template is desirably stored as an array of numbers on the computer or computers used to verify the legitimacy of the security label in question. If the nonlinearly additive color mixing is strong and the resultant spectra complex, the matching templates for legitimate security label protected items can be made public without compromising the protected item.
  • the method of the present invention lends itself to implementation via computer, computer-controlled inkjet printers and computer networking technology. That is, the template can be stored as an intensity contour in a computer, and measurements of markings on an object can be compared thereto to determine authenticity.
  • the matching template can be stored at a remote server, with measured (tested) objects at a distant location having the measurements sent, for example, over the Internet, for comparison with the matching template at the remote server.
  • coloring material is applied to a substrate, and such coloring material is selectively reacted so as to change the spectral response of reacted portions thereof. Again, due to difficulty in reverse engineering the spectral response of reacted portions, difficulty in counterfeiting is enhanced.
  • the present invention has many uses, both in connection with high-security and low-cost implementation.
  • the present invention can be used in general for document security, counterfeit detection and physical access control (for example, in optical card keys) .
  • Various specific uses include trademark and label verification, use directly as an optical card key, credit card protection, identification badge security, passport and visa verification, check verification, and identification document (e.g., birth certificate and immigration card) authentication.
  • the present invention can be utilized on ownership or title documents in order to verify authenticity thereof (prevent counterfeiting) , and can be utilized for protecting brand name goods and labeling semiconductor chips.
  • the present invention can also be used for verifying music and video CDs, verifying software source disks and verifying drug prescriptions.
  • the present invention can also be used for providing password control for high value software, authenticating collectibles, providing protection for entertainment and event tickets and guarding against forged parts certification.
  • the present invention can also be utilized for providing counterfeit-resistance tags for legal and financial documents.
  • the present invention can provide tamper resistant seals and labeling, and can also be utilized for providing postage stamps .
  • the present invention moves in a different direction for combating the counterfeiter. It does not rely upon denial of access to sophisticated and expensive hardware, but relies upon methods more akin to cryptography, with the ability to reproduce a security tag being dependent upon possession of a piece of information similar to a cryptographic key rather than the exclusive possession of certain pieces of hardware. Without possession of the specific information key, even if the counterfeiter is in possession of the original printed object and printing hardware used to create it, counterfeiting can not easily be achieved. Accordingly, the present invention enables a security printing technique to be achieved without the need for sophisticated printing hardware or restricted access materials.
  • the use of this technique for the present invention is not dependent upon a person's ability to purchase expensive hardware or control distribution of restricted access raw materials, and potentially enables low-cost consumer-grade computer hardware to be used to print secure documents .
  • the present invention is more resistant to being compromised by thefts of raw materials or from attacks by a well-financed counterfeiter .
  • the printers and readers used in the present invention can be provided by applying available technology for some custom modifications of "off the shelf” items.
  • the printers used in the present invention for example and not to be limiting, have firmware modifications to allow them to be commanded to print ink dots directly on top of previously printed ink dots. Since current printers print complex colors by printing a multi-color mosaic of individual primary colors, "off the shelf” printers will require an internal operating code modification to print dots on top of each other.
  • the readers can be assembled using "off the shelf” components and some custom software.
  • the present invention can be used in combination with conventional security printing methods, to provide an even further enhanced security and confidence level in avoiding counterfeiting.
  • conventional security printing methods for instance, the use of restricted-access, custom inks, non-commercially available ultra-high resolution print heads, and non-standard wavelength verification, and the use of print heads which print with much larger numbers of different ink types than commercial print heads, are examples of augmenting the present invention with conventional security printing techniques.
  • a further advantage according to the present invention is that it becomes economically practical to print and have archived unique security labels for each individual item to be protected. This is in contrast to documents protected by conventional security labels such as holograms, where a single successful forgery can be used to compromise thousands of protected documents .
  • the potentially very low cost of the optical reader combined with verification of patterns over the Internet, can allow the average consumer or employer to check the authenticity of brand name goods, collectibles and legal documents (for example, checks, diplomas, and immigration work permits) .
  • counterfeiting by label transfer has been used as a method of defeating optical variable device-based (for example, hologram-based) security labeling.
  • optical variable device-based for example, hologram-based
  • amusement park ride tickets might be printed with an identical low density dot pattern verified at only one wavelength by readers having the matching pattern stored locally in its own memory.
  • Diplomatic passports might have security labels which utilize proprietary inks, have million drop arrays printed with nonstandard ultra-high resolution print heads, have imaging done at multiple wavelengths including in the infrared and ultraviolet, and require confirmation by multiple remote servers, providing a very high level of security.
  • the present invention has the additional advantage of great flexibility in its application.
  • Figs, la- Id are graphs for illustrating linearly additive color combining of spectral responses.
  • Figs. 2a-2c illustrate nonadditive combining of spectral responses.
  • Fig. 3 illustrates schematically the forming of an ink composition from a plurality of ink components, according to the present invention.
  • Fig. 4 illustrates schematically the forming of markings on a substrate according to the present invention.
  • Fig. 5 illustrates schematically the verification of authenticity of a printed object, according to the present invention.
  • Fig. 6 illustrates a reader used for verification of authenticity.
  • Fig. 7a is a graph showing respective absorbances, at different light wavelengths, of Sodium Fluorescein and
  • Figs. 7b-7j are graphs showing absorbance, at different light wavelengths, of various mixtures of Sodium Fluorescein and Brilliant Green, as compared to a predicted (theoretical) linearly additively combining of absorbances of such mixtures of Sodium Fluorescein and Brilliant Green.
  • Fig. 8a is a graph showing respective absorbances, at different wavelengths, of Toluidine Blue O and Acrydine Orange individually; and Figs. 8b-8j are graphs showing absorbance, at different light wavelengths, of various mixtures of Toluidine Blue O and Acrydine Orange, as compared to a predicted (theoretical) linearly additively combining of absorbances of such mixtures of Toluidine Blue O and Acrydine Orange .
  • the present invention is described in connection with a set of ink components or ink composition, or a method of printing or method of verification, "comprising” or “including” specific components, or “comprising” or “including” specific steps. While the set or composition, or method, is described as including or comprising specific components or specific steps, it is contemplated by the inventors that the set or composition of the present invention can also consist essentially of, or consist of, the recited components, and that the methods of the present invention can also consist essentially of, or consist of, the recited steps. Accordingly, throughout the present disclosure any described set or composition or method can consist essentially of, or consist of, the recited components or materials, or recited steps.
  • a method of implementing difficult reversibility in the printing and read-out relationship utilizes combining different spectral responses of different materials, which have nonlinear color mixing characteristics, to make arrays of markings, each marking having a unique spectral response.
  • the printing uses inkjet ejectors of pigments and phosphors having the nonlinear color mixing characteristics, to make arrays of colored microdots, each dot having a unique spectral response.
  • a dot e.g., microdot
  • arrays of, e.g., microdots are used.
  • the dots act as optical intensity references to each other so far as automatically providing a relative average reference for intensity comparisons at a given wavelength.
  • the trap-door hard-reproducibility is based on the fact that by using mixing of materials according to the present invention, making a unique pattern and then, empirically measuring the spectral response of the resultant microdot array to make an authentication template, is a relatively easy task.
  • discovering the base pigments/dyes used and the proportions of the pigments/dyes used for each of the tens of thousands of dots in, e.g., a security label is a far more difficult reverse engineering problem when inks are used which nonlinearly color mix.
  • Elements (2), (3) and (4) can be implemented utilizing, respectively, industry-standard inkjet printers, CCD/CMOS video conferencing cameras, and standard pattern recognition and networking software.
  • the present invention is amenable to use of low cost and widely accessible hardware and software, to be used in combination with the nonlinearly color mixing inks .
  • nonlinear spectral response combining can be achieved by utilizing inks which exhibit multiple fluorescent absorption and re-emission bands. Pigments/dyes which block out wavelengths near fluorescent absorption lines will affect the spectral response at wavelengths away from where their pigments/dyes directly effect the absorbed or reflected light. Light emitted by one fluorescent band conversely can be absorbed and re-emitted at other colors. The characteristics of a fluorescent response of a dye can be made to change depending upon the presence of absence of trace non- light emitting chemicals. Nonfluorescent chemically active dyes/pigments which react together when mixed can also be used to achieve a nonadditive spectral response when combined.
  • the inks are inkjet inks (that is, can be applied by an inkjet printer) .
  • use of pigments of relatively large particle size are not preferred, since they cannot be utilized in an inkjet ink.
  • the components can be chemically reactive with other dyes/pigments in the set or with noncoloring chemicals.
  • the nonlinearly additive spectral response of the combination has a percentage deviation, from a predicted spectral response when linearly additively combining spectral responses of the invention, components of the mixture, which is greater than 20% (that is, the deviation at a specific wavelength, as a percentage of the theoretical or predicted, is greater than 20%) .
  • Preferred inks to be used as inkjet inks, for the present invention are from a class that is described by their manufacturers as metachromatic, that is, variable in color depending upon their chemical environment. Examples of such colorants are Safranin O, Azure B, Toluidine Blue, Acrydine Orange, Methyl Violet and Bismarck Brown Y. Other inks that are usable are those which in combination with other selected inks directly chemically react with each other, such as Sodium Fluorescein and Brilliant Green, which when mixed precipitate the colorants out of the solution.
  • a third class of inks are those such as Rhodamine B and Brilliant Green which are fluorescent dyes which in combination change each other's absorption and emission spectra such that nonlinearly additively combining the spectral responses occurs.
  • the particles preferably have fluorescent cross-interaction with other pigments/dyes such that nonlinearly additively combining of spectral response, at a percent deviation from linear of greater than 20%, can be achieved.
  • an ink set to be usable for the purposes of the present invention printed using an inkjet printer, must contain pigments or dyes which are (1) ejectable from inkjet devices; and (2) have a percentage of the possible dot mixtures, greater than the error criteria for array rejection, which nonlinearly additively combine at a percentage greater than the resolution, of the system, for the spectral response of the mixtures .
  • the present invention is not limited thereto and, for example, non-inkjet inks based on fluorescent solids can also be used.
  • Such inks can, preferably, be deposited by color laser printers or dry contact printing.
  • Fig. 3 schematically illustrates the formation of the ink composition 27 from ink compositions 25a-25e.
  • the pigment particles desirably have fluorescent cross-interactions with overlapping absorption and emission bands that have interactions sufficient to produce nonlinearly additively combining of the spectral responses at quantitative levels such that deviation of greater than 20% from predicted linearly additively combining of the spectral responses is achieved.
  • Conventional press and roller contact printing techniques while not as ideal as inkjet methods for implementing this invention, can also be used to print security labels based on this combinatorial mixing technology.
  • One example is the use of contact printing techniques for printing a large number of identical security tags.
  • a set of premixed inks from a set of inks designed to nonlinearly additively combine can be applied from a multireservoir inking pad onto the selected area of a roller or flat plate type printing press that contains the image of the security label.
  • Post-development of non- inkjet inks is possible by depositing powder-based pigments onto paper and then depositing solvent microdots over selected regions to allow chemical reaction.
  • the dry-printed security label can be placed in a vapor- filled chamber to allow deposited dyes/pigments to chemically react with each other.
  • nonlinearly additive color mixing can also be used.
  • chemical cross- reactions between dyes, and between dyes and noncoloring chemical compounds mixed with the dyes can be utilized for providing the nonlinearly additively combining of the spectral responses; and chemical cross-reaction between dyes that, for example, precipitated out colorants leaving a clear solution with a dark colored solid powder, can also be used.
  • the anti-counterfeiting technology according to the present invention is dependent for its effectiveness, in part, on the difficulty of replicating a dot made by combining a discrete set of inks given only its measured spectra.
  • the first criteria that this method preferably meets, to be effective, is that the number of possible mixtures be large enough that a counterfeiter could not simply print a massive dot array containing all possible mixes, scan them, and then make a look-up table.
  • the present technique can be made secure against this form of brute force attack. That is, current inkjet printers use up to 7 different ink colors in their print heads.
  • printers using increased numbers of different ink colors in their print heads, with increased resolvable color change levels per color be used, in order to be secure against brute force attack.
  • the composition of the base inks (for example, 16 base inks in a preferred embodiment) were kept secret or they were mixed from a custom kit by the end user.
  • the nonadditive color mixing inks In order to defeat using linear mixing to replicate an ink dot array, the nonadditive color mixing inks must controllably introduce nonadditive changes to the spectra at a percentage change level greater than the brightness resolution range of the viewer or the smallest incremental change in spectra due to the mixing resolution of the dyes. Otherwise, the nonlinear deviations from the predicted spectra would be lost in the system noise and be indistinguishable from linear mixing.
  • CCD and CMOS monochrome cameras a typical type of reader of the pattern, are digitized typically at 8-bit (256 levels) and 12 -bit (4096 levels) brightness level.
  • the optical system is not likely to be a limiting factor.
  • the more serious problem will probably be the limit given by the smallest incremental addition of ink to a dot that would give a repeatable measurable change in its spectra.
  • the chemical mixing resolution of the dyes (defined here as the smallest change in deposited dye that will produce a repeatable detectable distinct spectral change) , rather than the intensity resolution of the optical system, is thus likely to limit the applicability of the present technique.
  • the spectral response (e.g., reflectance, fluorescence and/or absorption, but not limited thereto) of an object does not have a one-to-one correlation with color as perceived by the human eye. Many different combinations of spectral lines can be perceived by the human eye as being the same color.
  • Computer display and printing technology depend upon this limited tricolor response of the human eye to form visually acceptable replicas of objects and scenes that have far greater spectral complexity than the limited pigments of a printer or phosphors of a cathode ray tube can synthesize.
  • the scanning, display and printing hardware in personal computer hardware is incapable, because of basic hardware limitations, of replicating the true spectral response of real world objects. This makes conventional scanners and printers useless for analyzing or counterfeiting, in connection with the technique of the present invention.
  • a preferred embodiment is to dispense and mix the inks at the location of the final printed dot using inkjet technology.
  • the lowest cost implementation would be for custom print heads or ink cartridges containing custom security inks, which are compatible with industry standard printers.
  • Print head technology such as that of Hewlett-Packard Corp., in which the ink reservoir is integral with the ejector, is preferred.
  • a printer that allows changing of the print head while maintaining a paper position index will allow the insertion of custom high-security print heads, where restricting access to the inks is part of the total security system.
  • Other methods for making the pattern such as mechanical contact deposition of the inks and xerography, while possible, are less ideal.
  • some sort of protective overcoating is provided for the printed security label .
  • a protective overcoating could be a clear plastic thermal laminate, a clear adhesively attached plastic sheet, or a clear printed-on overcoat, but is not limited to one of these illustrative overcoats.
  • Application of the protective overcoat may effect the optical properties of the ink mixtures; and for this reason, the read operation to generate the matching template should desirably take place after the protective overcoating is applied.
  • the most straightforward hardware for performing verification of authenticity of the pattern utilizes a monochrome solid state (CCD or CMOS) camera with a pixel density sufficient to resolve the printed security dot array.
  • a filter wheel over the illumination source can be used to vary the wavelength which excites the dots.
  • a filter wheel allows a selection of different wavelengths to view the dot array.
  • the illumination source used should optimally have significant emission in the blue and ultraviolet, in order to properly excite, e.g., dots which contain fluorescent compounds.
  • the frame rate of commercial low-cost solid state cameras is usually 30 Hz, which is more than adequate for the present application. The limited frame rate actually needed for verification allows great flexibility in cost optimizing the interface from the imaging hardware to the computer. Fig.
  • FIG. 6 illustrates schematically the reading of the spectra of a color pattern on a document.
  • the term document means not only a paper document, but any object such as a clothing label or an electronic part or a mechanical part upon which a label has been printed.
  • This apparatus shown in Fig. 6 is a reader used in verifying authenticity, and includes CCD camera 65 or equivalent, focusing lens 61 and spectral filter device 59 (for example, a color filter wheel) . Also included is light source 55; light from light source 55 irradiates document 35' having a pattern (label) thereon, and light 57 coming from the pattern on the document passes through the spectral filter device 59 and forms a spectrum filtered image 63 of the pattern on the document, which registers on the camera 65.
  • the light passing through the lens system is separated temporally into wavelength segments, thus the camera reads and transmits a time series of different color segments of the pattern.
  • the illumination of the pattern and the light 57 coming from the pattern may be of various types, such as fluorescent light from a visible light source; fluorescent light from a ultraviolet source; ultraviolet light from an ultraviolet source; diffuse reflected visible light from a visible light source; specular reflected light from a visible light source; and Raman scattered light from a visible light or infrared source.
  • Several kinds of light sources might be used; for example, an incandescent lamp, a gas lamp, a laser or an LED, for example.
  • Pattern generation using, for example, an inkjet printer, can be achieved as follows.
  • a seeded random number generator can be used to select the mixing used at each dot.
  • a key phrase for low security applications, a key phrase, the time of day or a selection of the contents of often used memory locations, can be used as the seed.
  • hardware seed generation utilizing thermal noise, atmospheric radio noise or radioactive decay can be used.
  • each dot could have its mixing proportions determined independently by a hardware-based random number generator. The user will then select the size, shape and dot density of the security pattern to be printed. The pattern is then printed out, and the mixing ratio used for each dot is stored.
  • Fig. 4 Creation of the pattern is shown, schematically, in Fig. 4. That is, printing is shown at the location indicated by reference character 29, the different ink components being shown respectively by reference characters 28a-28g.
  • the mixture at each dot can be determined by a random number generator. Shown at reference character 31 is a reading station, having monochrome camera 39, filter wheel 41 and document 35 with markings 37. Results measured by the camera 39 are passed to computer 40.
  • a monochrome image 45 having a separate image for each filter, is stored as a matching template 47, as a normalized intensity contour.
  • Fig. 5 shows document 35' whose authenticity is in issue, having markings 37' thereon.
  • Light from markings 37' pass through filter wheel 41 and form a separate image for each filter on camera 39.
  • the images from the camera 39 which represent measured array intensities, having a separate image for each filter, are shown by reference character 36, and are converted to numeric contour maps 38, which can then be uploaded via computer 40 to server computer 51 by way of, e.g., the Internet 49; and the numeric contour maps 38 are compared with a numeric array 53, as a matching template, at server computer 51.
  • the computer comparing the matching template and measured array can be at a remote location from where the measurement takes place; and the computer can be used to make comparisons from documents analyzed at many different locations.
  • the dot patterns are verified by being illuminated with monochromatic light and imaged through different monochromatic filters with a computer- interfaced CCD or CMOS camera.
  • the relative brightness of the dots is stored in the form of a two-dimensional contour map. Comparisons of these contour maps with reference templates made by imaging the original dot array are used to verify the authenticity of the security label.
  • the number of different illumination and viewing wavelengths used can be increased with the level of security required.
  • the dot pattern can be stored and matched at each wavelength as either a threshold on-off pattern of dots or as an analog intensity profile (contour plot) .
  • Monochromatic light is not required or is even desirable in some cases, for instance for nonfluorescent absorption- based dyes. What is needed, however, for implementation of the present invention is a light source with a well defined spectral content identical in both the readers used to make the matching templates and the readers used out in the field to authenticate these security labels.
  • a document protection system that requires a prohibitively expensive read-out system is of little use in the commercial world.
  • the recent availability of low-cost image capture cards and inexpensive miniature CCD and CMOS video cameras makes possible an affordable method of verifying the authenticity of a, e.g., microdot combinatorial array.
  • the camera and frame grabber costs are on the order of $200.00.
  • Narrow band monochromatic filters can sell for, e.g., $10.00-$20.00 each at wavelengths justifying mass production. The prices of these components have been rapidly decreasing.
  • Connecting imaging hardware to personal computers has recently become even cheaper with the new high-speed serial data interface (the new industry standard high speed serial interface ' s official designation is IEEE-1394 "FireWire").
  • the cost of an optical reader is in the low hundreds of dollars.
  • the digitization time for a single image with current technology low-cost cameras is on the order of 1/10 to 1/30 sec.
  • the present invention can provide speedy verification, at low cost.
  • spectral contour plots of the authentic documents It is not necessary to publicly publish the spectral contour plots of the authentic documents. Verification of authenticity can be done via the Internet or via local intranets. First, a series of images are acquired at different wavelengths. Next, at each frequency the imaging computer converts the imaged dot array into either a contour plot or a pattern of on-off dots. These extracted patterns are uploaded to the authentication computer that has stored the spectral template for the true document. If the pattern matches better than a given correlation coefficient, then a verification message is sent back over the network to the computer which read the document in question.
  • the potentially unique pattern of each document can also be used as a covert serial numbering useable for tracing the use of certain classes of secured documents such as access passes.
  • the preferred implementation is to have the reader convert the raw graphic images taken by the camera into a numeric contour map
  • One major disadvantage of sending the raw graphic image is the amount of data to be uploaded is from 10 to 100 times that required for uploading a preprocessed numeric contour map.
  • An additional problem is that the verification server will have a much higher processing load. This can adversely effect transaction throughput when this system is used in a high volume commercial application.
  • the advantage, however, is that the reader can be made simpler and cheaper. For applications where the expected number of transactions per unit time is expected to be low, sending the raw graphics images as is to the verification computer may be a viable option to cut the cost of the readers.
  • a 100 by 100 array read at 16 wavelengths with 8 -bit resolution generates 160 Kbytes of raw data which can require, e.g., about two cents worth of hard drive space to store.
  • this data block could be transmitted to a verification server in less than a tenth of a second.
  • the authentication pattern need not be a simple rectangular array.
  • the dots could also be printed such that they form the shape of a company trademark or logo, or are printed such that they form alphanumeric characters .
  • a spatially sparse array of, e.g., microdots can be printed, relying upon the small diameters of the microdots for invisibility.
  • visually transparent inks excited by ultraviolet light could be formulated.
  • the sparse dot and transparent dot techniques could also be useful as an anti- tamper security protection overlay which can be printed on top or original documents for assuring that photographs and signatures, for instance, have not been substituted or altered.
  • an ink cartridge is selected by the user. If duplication of the pattern at future dates by other authorized entities is necessary, then the inks will be selected from a standardized set. If high security is desired for creating authentication marks that will not require that the marks be reproducible by publicly available hardware, custom mixed inks can be used as the base combinatorial set .
  • the security ink cartridge can be made hardware-compatible with standard cartridges of inkjet manufacturers, so that mass-produced, low-cost commercial printers can be used. Alternately, for high security applications, ultra-high resolution print heads and printers could be custom made .
  • a seeded random number generator can be used to select the mixing used at each dot.
  • the user will then select the size, shape and dot density of the security pattern to be printed.
  • the pattern is then printed out and the mixing ratios used for each dot is stored.
  • the printed pattern is next placed in the user's multi- wavelength imaging verifier and either contour plots or thresholded dot patterns are measured and stored, creating a matching template.
  • the number of wavelengths these contour plots are taken at, and the wavelengths used for illumination and imaging, are determined by the intended use of the object.
  • a standardized public set of illumination and viewing wavelengths could be used for verification of consumer goods, collectibles and low-security financial documents.
  • a smaller subset could be used for applications such as amusement park ticket verification in which the resources devoted to counterfeiting is likely to be low.
  • an extensive and proprietary set of measurement wavelengths could be defined.
  • An object to be verified is imaged on a reader which, depending upon the application, can be a video camera assembly with rotary filter wheels for selecting illumination and viewing wavelengths. Alternately, for documents with a preknown size, such as identification cards or event tickets, the document could be fed into a custom reader. Contour plots are taken for each wavelength and normalized to 256 gray levels. These contour plots can be compared with an internal template and matched, or sent out over a computer network for verification. Remote instantaneous anonymous verification over the Internet could be used, for example, to combat counterfeiting of name brand consumer goods, collectibles and industrial components.
  • a response either from the internal database or over the computer network can either be a binary (valid-not valid) response or a confidence level.
  • an inkjet printer with multiple individually usable loadable color cartridges is used.
  • the number of ink channels preferably is on the order of 16.
  • the printer is of a type which is custom manufactured for this purpose and differs from consumer-grade printers by having a higher dpi (dots per inch) printing resolution, a larger number of ink channels and individually selectable ink reservoirs for each color.
  • Another modification needed for a printer optimized to implement real-time combinatorial mixing is that it is capable of being commanded to deposit ink drops on top of previously printed ink spots.
  • Current printers produce different colors by printing a matrix of non-overlapping dots composed of the primary colors, relying upon their small size and proximity for the human eye under normal viewing conditions to blend them together.
  • the internal-print head control firmware is thus not set up to print ink dots on top of previously laid- down dots .
  • the set of inks to be loaded into the printer for a particular printing job is selected by the user from a much larger set, and is then loaded into the printer. A record is kept of which subset is selected. This adds to the permutation problem for a counterfeiter.
  • Proprietary inks using exotic precursors can be used to add an economic denial-of-resources layer of security on top of the combinatoric security method.
  • the preferred inks are from a class that is described by the manufacturers as metachromatic, that is, variable in color depending upon their chemical environment, examples of such colorants being Safranin O, Azure B, Toluidine Blue, Acrydine Orange, Methyl Violet and Bismarck Brown Y; but other inks that are usable are those which directly chemically react with each other such as Sodium Fluorescein and Brilliant Green which when mixed precipitate the colorants out of solution.
  • metachromatic inks and chemically reactive inks there are inks, which produce nonlinearly additively combined spectra by cross-interacting fluorescent absorption and emission lines, which are also suitable for implementing the present invention.
  • the mixing ratios for each microdot are optimally determined by a hardware-based random number generator.
  • a hardware-based random number generator can use sources such as atmospheric radio noise, radioactive decay or thermal noise, and this hardware random number generator is used to determine the proportion of each ink to be applied to each spot .
  • This information could be deleted immediately after printing if there is no need to replicate the microdrop array security label.
  • the security label formed is as large and spatially dense an array of microdots as is physically possible to print onto the secured object or document.
  • each document or item to be protected receives a unique pattern, and a laminated covering is desirably applied over the pattern to prevent environmental degradation and deter attempts at direct chemical analysis of the microdots.
  • the array is characterized at multiple wavelengths, some publicly disclosed, some kept secret, and this matching template information of this array is stored at each verification computer or each verification device. In principle, even making this data public should not compromise the security of the object.
  • the microdot array can be imaged at all wavelengths it was originally characterized at and not just some small subset as might be done for low-cost commercial readers. Verification of a match with the template is done via multiple secure Internet server sites or locally secured intranets to minimize the chance of receiving a falsified verification by hackers. Public key cryptography could be used to verify the identity of the verification authority.
  • the technique according to the present invention uses combinatorial microdrop array printing, produces difficult-to- replicate objects by using a more cryptographically oriented approach that makes duplication of the security pattern dependent upon access to a data file or an information key.
  • the security object printed using this method is an array of dots, each dot having a unique spectral response.
  • the necessary difficulty of duplication by inspection of the printed array is physically implemented by printing the, e.g., security label using multiple inks ejected in different proportions to create each dot in the array.
  • these inks can be of a class that when reacted together they nonlinearly additively combine their spectral responses.
  • the nonlinearly additive combining is used to make it difficult to determine from the end spectral response of the mixture which inks and what proportions of each ink were used to make each dot.
  • the inclusion of multiple cross-interacting fluorescent compounds in the different inks can produce very complex spectra which makes replicating the complex color response of each dot virtually impossible unless the exact same inks in the exact proportions are used.
  • Figs. 7a-7j and 8a-8j illustrating spectral responses of mixtures of dyes which deviate from a predicted spectral response when linearly additively combining the spectral responses of each component of the mixture.
  • curves 66 and 68 respectively represent absorbance patterns of Sodium Fluorescein and Brilliant Green individually.
  • Figs. 7b-7j each show a measured absorbance of the physically mixed dyes, and a predicted linearly additive absorbance of the two dyes combined.
  • Figs. 7b-7j the curves represented by reference characters 67, 71, 75, 79, 83, 87, 91, 95 and 99 represent the measured absorbance of the physically mixed dyes, while the curves represented by reference characters 69, 73, 77, 81, 85, 89, 93, 97 and 101 represent the predicted linearly additive absorbance.
  • Fig. 7b has 10% Sodium Fluorescein and 90%
  • Fig. 7c has 20% Sodium Fluorescein and 80% Brilliant Green. Remaining Figs. 7d-7j incrementally increase the amount of Sodium Fluorescein by 10%, and incrementally decrease the amount of Brilliant Green by 10%. As can be seen in Figs. 7b-7j, the measured absorbance deviates from the predicted linearly additive absorbance, and these mixed dyes can be used according to the present invention.
  • Fig. 8a respectively shows the individual absorbance spectra of Acrydine Orange and Toluidine Blue O, by the curves represented by reference characters 103 and 105.
  • Figs. 8b- 8j are shown measured absorbances and predicted linearly additive absorbances of mixtures of the Toluidine Blue O and Acrydine Orange.
  • Fig. 8b includes a mixture of 10% Toluidine Blue O and 90% Acrydine Orange
  • Fig. 8c includes a mixture of 20% Toluidine Blue O and 80% Acrydine Orange.
  • the remaining Figs. 8d-8j respectively include amounts of Toluidine Blue O increasing incrementally by 10% and amounts of Acrydine Orange decreasing incrementally by 10%.
  • a document security and authentication technique is achieved which is simple and relatively resistant to counterfeiting, while being relatively inexpensive and which can use low-cost consumer grade hardware.
  • the technique is resistant to being compromised by thefts of raw material or from attack by well- financed counterfeiters, and is economically very satisfactory.
  • the method can be readily scaled for use in both low-and-high-security applications.
  • the print pattern is not limited to microdot arrays or objects such as logos and alphanumeric characters made up from suitably arranged microdots, but includes, e.g., continuous area gradient mixing of cross- reacting dyes forming images, logos, backgrounds or abstract patterns.
  • Narrow band filters can be used to view the images, allowing for greater discrimination of fine spectral variations but require greater levels of illumination which may limit ability to use low-cost imaging hardware.
  • CCD or CMOS cameras are presently preferred image verification hardware, e.g., for economic reasons, they are not the only means for viewing the patterns; vidicon and other vacuum tube based imagers illustratively can also be used.
  • any imaging method that can get a spectrally bandpassed image into a computer can in principle be used.
  • PDA's personal digital assistants
  • the present invention can be used for document security, counterfeit detection and physical access control (for example, in optical card keys) .
  • Ink components can be selected and mixed to form an ink composition, with a template of spectral response of this ink composition being made.
  • Spectral response of a marking on an object can be compared to the template, in making a determination of authenticity.

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Abstract

La présente invention concerne des séries de composants d'encre, des compositions d'encre, qui sont utilisées pour des inscriptions imprimées sur des documents de sécurité, et qui sont relativement difficiles à contrefaire. Cette invention concerne aussi les documents de sécurité ainsi formés, un procédé d'impression et un procédé d'authentification des documents imprimés. Les inscriptions formées à partir de ces compositions d'encre ont une réponse spectrale déviée par rapport à une réponse spectrale prévue lorsqu'elle est associée linéairement et de façon additive à des réponses spectrales de composants de la composition de l'encre, de sorte qu'il devient difficile de percer le secret de cette composition d'encre à partir de ces inscriptions. L'utilisation d'une pluralité d'inscriptions différentes, chaque inscription étant un micropoint, rend la contrefaçon encore plus difficile à réaliser. La fabrication d'un modèle des réponses spectrales du motif original, permet de comparer les réponses spectrales du motif d'un document inconnu à celles du modèle de façon à déterminer si le document inconnu est authentique. La réalisation de ces inscription est facilitée par l'utilisation d'une imprimante à jet d'encre.
PCT/US2000/015824 1999-06-10 2000-06-09 Serie de composants d'encre et composition d'encre utilisee pour des procedes relatifs a des documents de securite et produit de fabrication WO2000077104A1 (fr)

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EP1385637A1 (fr) * 2001-04-11 2004-02-04 Quantag Systems, Inc. Composition de marquage raman active et son identification
EP1385637A4 (fr) * 2001-04-11 2006-10-18 Quantag Systems Inc Composition de marquage raman active et son identification
EP1403333A1 (fr) * 2002-09-24 2004-03-31 Sicpa Holding S.A. Procédé et système d' encres pour marquer et authentifier les articles
WO2004029163A1 (fr) * 2002-09-24 2004-04-08 Sicpa Holding S.A. Procede et ensembles d'encre pour marquer et authentifier des articles
US8159657B2 (en) 2002-09-24 2012-04-17 Sicpa Holding Sa Method and ink sets for marking and authenticating articles
AU2003283239B2 (en) * 2002-09-24 2007-06-21 Sicpa Holding Sa Method and ink sets for marking and authenticating articles
US7892338B2 (en) 2002-09-24 2011-02-22 Sicpa Holding S.A. Method and ink sets for marking and authenticating articles
WO2005055237A1 (fr) * 2003-11-26 2005-06-16 General Electric Company Authentification d'articles; procede, articles et polymeres
US7094364B2 (en) 2003-11-26 2006-08-22 General Electric Company Method of authenticating polymers, authenticatable polymers, methods of making authenticatable polymers and authenticatable articles, and articles made there from
US7169615B2 (en) 2003-11-26 2007-01-30 General Electric Company Method of authenticating polymers, authenticatable polymers, methods of making authenticatable polymers and authenticatable articles, and articles made there from
EP1734083A3 (fr) * 2005-03-01 2008-08-06 Evonik Degussa GmbH Suspension comprenant un colorant insoluble dans l'eau et un composé hétérocyclique
WO2007027073A3 (fr) * 2005-08-30 2007-07-05 Vladimir Schiliov Procede d'identification spectrale d'objets de ressources materielles et dispositif d'identification associe
WO2007027073A2 (fr) * 2005-08-30 2007-03-08 Vladimir Schiliov Procede d'identification spectrale d'objets de ressources materielles et dispositif d'identification associe
US8152073B2 (en) 2008-04-30 2012-04-10 Polyonics, Inc. Method and apparatus for the detection of counterfeiting
US8915998B2 (en) 2008-11-27 2014-12-23 Evonik Carbon Black Gmbh Pigment granulate, method for producing the same and use thereof
US8852739B2 (en) 2010-02-23 2014-10-07 Evonik Carbon Black Gmbh Carbon black, method for the production thereof, and use thereof
WO2013053774A2 (fr) 2011-10-14 2013-04-18 Sojasun Technologies Encre biodegradable pour impression et/ou ecriture infalsifiable
CN102936437A (zh) * 2012-11-27 2013-02-20 中国人民银行印制科学技术研究所 具有红外特征的金属效果油墨
CN102936437B (zh) * 2012-11-27 2014-02-26 中国人民银行印制科学技术研究所 具有红外特征的金属效果油墨
WO2016093924A3 (fr) * 2014-09-29 2016-09-01 Northwestern University Compositions d'encres de sécurité fluorescentes supramoléculaires encodées
US11267979B2 (en) 2014-09-29 2022-03-08 Northwestern University Supramolecular encrypted fluorescent security ink compositions
EP3220112A1 (fr) * 2016-03-01 2017-09-20 Matrix Vision GmbH Bildverarbeitung Dispositif comprenant au mois un module de capteur optique et procédé de fonctionnement associé
WO2024013693A1 (fr) * 2022-07-13 2024-01-18 Politecnico Di Milano Etiquette anti-contrefaçon pour l'authentification de marchandises

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