Optically variable security feature

Abstract

A security document includes a printable substrate (105, 301, 401, 501, 601, 701) having a hybrid security feature (320, 400, 510, 600, 700). The hybrid security feature includes a first sub-region (305, 605, 705) comprising a first area of optically variable ink, and a second sub-region (310, 405a-c, 610, 710) comprising a second area of a first fluorescent ink. The first fluorescent ink of the second sub-region glows only under ultraviolet light. The hybrid security feature presents an optically variable effect characterized by, when viewed in natural light, the optically variable ink of the first sub-region presents an optically variable effect, and the first fluorescent ink of the second sub-region does not glow, and when viewed in ultraviolet light, the optically variable ink of the first sub-region appears as one or more solid colors, and the first fluorescent ink of the second sub-region glows.

Description

OPTICALLY VARIABLE SECURITY FEATURETECHNICAL FIELD

[0001] The present disclosure relates to enhancing security documents, such as currency notes, passports and other documents comprising surface-applied micro-optic security devices by extending the functionality of given volumes of certain optically variable, machine -readable materials. More specifically, this disclosure relates to security documents with fluorescing optically variable security features and methods for producing same.BACKGROUND

[0002] Manufacturing passports, banknotes, and other documents (referred to herein as “security documents”), whose constructional features include hard-to-reproduce indicia of the documents’ authenticity against counterfeiting, remains an ongoing source of technical challenges and opportunities for improvement in the field of security document design.

[0003] The technical challenges associated with manufacturing security documents of the quality expected by, for example, central banks and passport offices, include achieving efficiency at scale, as banknotes and other security documents are, by necessity, produced and replaced in enormous runs. In other words, the challenges of developing security documents are twofold, and include: (1) developing authenticating features which are hard to duplicate and make it easy to spot counterfeits, and (2) also being able to continuously produce large numbers of such documents.

[0004] Proprietary, hard-to-produce, optically variable inks, including proprietary, hard-to-reproduce, inks with machine readable characteristics, such as SPARK® by SICPA, provide solutions to the first aspect of the aforementioned technical challenge, in that they provide eye-popping color-change effects, are not readily reverse-engineered, and are subject to controlled distribution. However, much of what makes such proprietary, hard-to-reproduce, variable inks so effective for use as anti-counterfeiting features only adds to the technical challenges of producing security documents utilizing such inks in the print runs required for many security document applications, notably issuing, and replacing banknotes. For example, SPARK® ink is an industry-leading color-changing ink and used as an authenticating feature on many countries’ banknotes, leading to a stressed supply and limited availability. At best, high-performing inks like SPARK® are sufficiently available in quantities for a run of security documents but are expensive. At worst, the high global demand for such inks can make them unavailable.

[0005] As modifying security document designs in response to supply shortages (i.e., standardization is generally of paramount importance), or postponing pnnting and replacing banknotes are not valid options, and by design, there are no readily available alternatives to the aforementioned proprietary inks, developing security features which provide all of the visual effects of proprietary, hard-to-reproduce, optically-variable inks, while better ensuring the ability to reliably produce security documents at large scales, remains a source of technical challenges and opportunities for improvement in the art.SUMMARY

[0006] The present disclosure illustrates embodiments of an improved optically variable security feature and methods for making security documents incorporating same.

[0007] In a first embodiment, a security document includes a printable substrate having a substantially flat exterior surface. The security document includes a hybrid security feature disposed on the substantially flat exterior surface. The hybrid security feature includes a first sub-region comprising a first area of optically variable ink, the first area bounded by a first edge and a second sub-region comprising a second area of a first fluorescent ink, the second area bounded by a second edge. The second edge is in register with at least a portion of the first edge. The first fluorescent ink of the second sub-region glows only under ultraviolet light. The hybrid security feature presents an optically variable effect characterized by: when viewed in natural light, the optically variable ink of the first sub-region presents an optically variable effect, and the first fluorescent ink of the second sub-region does not glow, and when viewed in ultraviolet light, the optically variable ink of the first sub-region appears as one or more solid colors, and the first fluorescent ink of the second sub-region glows.

[0008] In a second embodiment, a method of making a security document includes, on a printable substrate having a substantially flat exterior surface, forming a first sub-region of a hybrid security feature comprising a first area of optically variable ink, the first area bounded by a first edge and forming a second sub-region of the hybrid security feature comprising a second area of a first fluorescent ink, the second area bounded by a second edge. The second edge is in register with at least a portion of the first edge. The first fluorescent ink of the second sub-region glows only under ultraviolet light. The hybrid security feature presents an optically variable effect characterized by: when viewed in natural light, the optically variable ink of the first sub-region presents an optically variable effect, and the first fluorescent ink of the second sub-region does not glow, and when viewed in ultraviolet light, the optically variable ink of the first subregion appears as one or more solid colors, and the first fluorescent ink of the second sub-region glows. Other technical features may be readily apparent to one skilled in the art from the following figures, descriptions, and claims.

[0009] Before undertaking the DETAILED DESCRIPTION below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document. The term “couple” and its derivatives refer to any direct or indirect communication between two or more elements, whether or not those elements are in physical contact with one another. The terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation. The term “or” is inclusive, meaning and / or. The phrase “associated with,” as well as derivatives thereof, means to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, have a relationship to or with, or the like. The phrase “at least one of,” when used with a list of items, means that different combinations of one or more of the listed items may be used, and only one item in the list may beneeded. For example, “at least one of: A, B, and C” includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A and B and C.

[0010] Definitions for other certain words and phrases are provided throughout this patent document. Those of ordinary skill in the art should understand that in many if not most instances, such definitions apply to prior as well as future uses of such defined words and phrases.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts:

[0012] FIG. 1 illustrates an example of a security document according to various embodiments of this disclosure;

[0013] FIG. 2 illustrates a prior art security feature formed by printing optically variable ink in a solid field;

[0014] FIGS. 3A through 3C illustrate an example of a hybrid optical security feature according to various embodiments of this disclosure;

[0015] FIGS. 4 A through 4D illustrate an example of a hybnd optical security feature according to some embodiments of this disclosure;

[0016] FIGS. 5 A through 5D illustrate an example of a hybrid optical security feature according to some embodiments of this disclosure;

[0017] FIGS. 6 A through 6D illustrate additional example elements of an improved optically variable security feature according to various embodiments of this disclosure;

[0018] FIGS. 7A through 7D illustrate additional example elements of an improved optically variable security feature according to various embodiments of this disclosure; and

[0019] FIG. 8 illustrates operations of a method for making security documents with hybrid security features according to certain embodiments of this disclosure.DETAILED DESCRIPTION

[0020] FIGURES 1 through 8, discussed below, and the various embodiments used to describe the principles of the present disclosure are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged security document.

[0021] Although the present disclosure has been described with various embodiments, various changes and modifications may be suggested to one skilled in the art. It is intended that the present disclosure encompass such changes and modifications as falling within the scope of the claims.

[0022] FIG. 1 illustrates an example of a security document according to certain embodiments of this disclosure.

[0023] The proliferation of imaging tools, raw materials, and some of the basic know-how associated with the production of security documents has enabled counterfeiters and other malicious actors to make increasingly better facsimiles of the printed features of security documents, such as passports and banknotes. However, one area in which manufacturers of legitimate security documents can continue to produce documents which are, even to untrained end users, visually distinguishable from counterfeits is through the use of optically-variable security inks, which provide hard-to-reproduce visual signatures (for example, changing color in response to changes in viewing angle) of authenticity. Security inks, including, without limitation, SPARK® can add meaningful counterfeiting protection in that they: a.) provide visually striking optical effects; b.) are difficult to produce; and c.) are subject to distribution controls and not readily available to counterfeiters and other malicious actors. However, the qualities which make such inks hard to obtain by counterfeiters can also impose challenges upon legitimate manufacturers, who may not be able to source such materials in the necessary quantities.

[0024] As discussed in greater detail herein, certain embodiments according to this disclosure provide examples of security features and methods which make optimized use of high-performance, limitedavailability performance inks in ways that use less ink (thereby making larger print runs more reliably possible) but do not require dilution of the visual effects provided by such inks.

[0025] Referring to the non-limiting example of FIG. 1, an example of a security document 100 according to various embodiments of this disclosure is shown. In this illustrative example, security document 100 is a currency note, though other embodiments (for example, tickets, passports, identification papers, etc.) are within the contemplated scope of this disclosure. According to some embodiments, security document 100 comprises a substrate 105. Substrate 105 can be a polymeric substrate, such as a thin section of PET or biaxially oriented polypropylene (BOPP) film. Substrate 105 can also be formed from a wet web of fibrous material (for example, wood pulp, cotton fiber, linen fiber, flax fiber, sisal fiber, hemp fiber, Abaca fiber, Kozo fiber, Mitsumata fiber, bamboo fiber, Kenaf fiber, and / or synthetic fiber), which is laid down (for example, in a Fourdrinier process) at a first, baseline fiber density. Regions of the web in which the first fiber density is not altered while the web is wet (for example, through the use of wire rolls, electrotypes or other watermarking tools) prior to pressing, drying, and, in some embodiments, calendaring, form bulk regions 110 of security document 100. As used in this disclosure, the expression “bulk region” encompasses a portion of a fibrous substrate embodying one or more of a baseline fiber density, baseline light absorption, or baseline caliper thickness. Put differently, as used in this disclosure, the expression “bulk region” encompasses portions of a finished fibrous substrate in which the locations of the constituent fibers are not deliberately altered (for example, through the use of embossed wirecloth or electrotypes) as part of the papermaking process.

[0026] As shown in the explanatory example of FIG. 1, security document 100 can include one or more security features 115 adhered to the surface of security document 100. Security feature 115 comprises a thin section of material with one or more optical structures, such as structures comprising an embossed or cast-cured outer surface that provides an optically variable effect. Examples of optical structures providedon security feature 115 include, without limitation, micro-lenses, diffractive structures, and micro-optic icons. Examples of optically variable effects provided by the optical structures of security feature 115 include, without limitation, holograms, color shift effects, and synthetic images, characterized by the synthetic projection of portions of image icons across an array of image icons by focusing elements of an array of focusing elements, wherein the scale ratio (z.e., the ratio of the repeat period of the focusing elements to the repeat period of the image icons) is approximately 1.000.

[0027] Security document 100 further comprises one or more watermarks 120. According to various embodiments, watermarks 120 comprise one or more regions in which the fiber density of substrate 105 is deliberately altered (either increased or decreased) from the fiber density in bulk region 110 to form a visible pattern of light (z.e., allowing more light to pass in transmission through the fibrous substrate than bulk region 110) and / or dark (i. e. , less light to pass in transmission through the fibrous substrate than bulk region 110) elements. One or more watermarks 120 may, in some embodiments, be formed using a dandy roll or other wire cloth embossing screen. In some embodiments, one or more watermarks 120 may be formed using an electrotype. In some embodiments, at least a portion of watermark 120 is covered by part of security feature 115, wherein security feature 115 is maintained in contact with functional watermark 120 by an adhesive bond.

[0028] Security document 100 can also include or more regions 125 printed with one or more optically variable inks, such as SPARK®. While there is no particular technical reason for doing so, using such inks for the denomination numbers of banknotes (as has been done with several generations of the United States $10 bill) is a design choice among currency designers. However, other locations on the face(s) of security documents are possible and within the contemplated scope of this disclosure. The principal design constraint with regard to using hard-to-reproduce optically variable inks is that hard-to-reproduce optically variable inks are provided as part of a feature that is large enough (and can be reasonably be expected) to be seen by end users.

[0029] As will be explained in greater detail herein, certain embodiments according to this disclosure extend the functionality of hard-to-produce, hard-to-source optically variable inks to address the technical problem of reliably ensuring that security documents with security features that use such inks can be produced at scale, without diminution in the overall performance of the security features as safeguards against counterfeiting. Indeed, in addition to reducing the amount of optically variable ink required to complete a printing run, certain embodiments according to this disclosure enhance the counterfeit resistance of security documents by adding further ink registration challenges unlikely to be solved by counterfeiters and malicious actors. Additionally, certain embodiments according to this disclosure leverage optically variable inks to create new, hybrid security features.

[0030] FIG. 2 illustrates a prior art application of an optically variable ink, such as SPARK®. As shown in the figure, security feature 200 comprises a printed indicium of the currency value of a banknote printed as a combination of letters and numbers in optically variable ink, wherein each letter or number comprises a single region uniformly covered in optically variable ink. Skilled artisans will appreciate thatthis approach is sub-optimal in at least the following regards: First, the solid field design of the individual features of the security feature provides no fallback protection against malicious actors in possession of optically-variable inks. Given the simplicity of printing the design, a malicious actor in possession of optically-variable ink would likely be able to reproduce a suitable facsimile of the design of the optical feature in the figure. Second, the solid field application of optically variable ink across the full area of the optically variable feature presents an inefficient use of precious optically variable ink, in that the full area of the security feature does not need to be covered with optically variable ink for such ink to have the desired anti-counterfeiting effect. Multiplied over a run of thousands, or even millions of security documents (for example, banknotes) the design inefficiencies of security feature 200 can limit the extent to which this design can be produced at scale.

[0031] FIGS. 3 A through 3C illustrate elements of an improved optically variable security feature according to various embodiments of this disclosure. For convenience of cross-reference, elements common to more than one of FIGS. 3A-3C are numbered similarly.

[0032] As described herein, the micro-optic security feature described with reference to FIGS. 3A-3C improves on the prior art optically variable security feature 200 of FIG. 2 in that it, without limitation, makes more efficient use of proprietary, imperfectly available optically variable inks, thereby better ensuring the ability to produce security documents at scale, and at the same time, imposes additional technical challenges upon counterfeiters, including counterfeiters with access to optically variable inks.

[0033] Referring to the explanatory example of FIG. 3 A, optically variable security features according to this disclosure can include a first sub-region 305, comprising an area of an optically variable ink, or an optically variable magnetic ink (for example, an ink that is both optically variable, and which has a characteristic magnetic signature enabling detection and authentication by a magnetic bill reader). As shown in the figure, first sub-region 305 comprises at least one edge, bounding the first sub-region. In this case, first sub-region 305 comprises a plurality of interior edges (for example, interior edge 307b) and exterior edges (for example, exterior edge 307a).

[0034] Referring to the illustrative example of FIG. 3 A, optically variable security features according to this disclosure can also include a second sub-region 310, comprising a second area of an ink which glows under ultraviolet light, and is bounded by a second edge. In this example, second sub-region 310 comprises a plurality of boundary edges (for example, exterior edge 315A and interior edge 315B).

[0035] Though not shown in FIG. 3 A, first sub-region 305 and second sub-region 310 are provided on a common substrate 301 such that at least one edge of first sub-region 305 is in register with at least one edge of second sub-region 310. Substrate 301 can, for example, be a section of fibrous substrate (for example, linen currency paper) or a polymeric substrate. As shown and described in greater detail with reference to FIGS. 3B and 3C, in this explanatory example, all of the boundary edges of second sub-region 310 register to edges of first sub-region 305.

[0036] In this way, by dividing what, under the prior art approach described with reference to FIG. 2, would otherwise be a solid field of optically variable ink into at least two sub-regions comprising at leastone first sub-region comprising an area of optically variable ink bounded by at least a first edge, and a second sub-region comprising an area of a first fluorescent mk bounded by at least a first edge, certain embodiments according to this disclosure facilitate at least the following technical and practical benefits. First, for a printed optically variable security feature having the same overall area as the prior art security feature 200 of FIG. 2, embodiments according to the present disclosure use less optically variable ink, thereby better ensuring the ability to produce security documents at scale. Second, as noted with reference to FIG. 2, the design of prior art security feature 200 would be straightforward enough to duplicate by a malicious actor in possession of the correct optically-variable ink. By contrast, in embodiments according to this disclosure, the first sub-region needs to be registered to the second sub-region. Skilled artisans will appreciate that achieving registration between successive printing layers requires not only skill in the art of the relevant printmaking techniques (for example, intaglio or offset printing), but also surplus ink for machine setup and test runs to achieve the correct registration. For legitimate actors producing large quantities of security documents, though necessary, the wastage of inks associated with setup is generally trivial in comparison to the consumption of inks during production runs. Put differently, the wastage of ink associated with setup and achieving proper registration between regions of optically-variable ink and regions of fluorescent ink does not scale linearly with the size of the print runs. However, for malicious actors with limited access to small quantities of stolen or otherwise illegitimately sourced optically variable inks, the unavoidable, wastage of materials associated with setup achieving proper print registration between a first sub-region of optically variable ink and a second region of fluorescent ink can significantly deplete such limited supplies, significantly (as compared to legitimate actors operating on much, much larger production scales) reducing the amount of material available for production of counterfeit security documents. Third, optically variable security features comprising registered sub-regions of optically variable and fluorescent inks can, as described with reference to FIGS. 3B and 3C, present multiple characteristic images for authentication.

[0037] Referring to the explanatory example of FIG. 3B, a first photographic view of optically variable security feature 320, which comprises a registered combination of first sub-region 305 and second subregion 310, as it appears in natural, or visible light is shown in the figure. As shown in FIG. 3B, first subregion 305, in particular, lower region 309, which appears to sparkle in the photograph presents an optically variable effect - specifically, the luminescent, color changing “sparkle” characteristic of SPARK® ink. By contrast, the fluorescent ink(s) of second sub-region 310 appear flat (i.e., not glowing). Thus, optically variable security feature 320 has a first characteristic appearance - its appearance in natural, or visible light.

[0038] Referring to the explanatory example of FIG. 3C, as second photographic view of optically variable security feature 320, as it appears in ultraviolet light, is shown in the figure. As shown in the figure, the registered use of both optically variable and fluorescent inks provides a second characteristic appearance. As shown in illustrative example of FIG. 3C, under UV light, substrate 301 and first sub-region 305 appear dark and as solid colors, while second sub-region 310 glows or fluoresces in response to theexposure to UV light. The interplay between the first and second sub-regions of dissimilar inks creates further indicia of authenticity.

[0039] In the various embodiments of this disclosure, the use of the optically variable ink in just a first sub-region, such as first sub-region 305, and use of the fluorescent ink in one or more other sub-regions, such as the second sub-region 310, provides for a substantial reduction in use of the optically variable ink. For example, in previous applications of optically variable ink, an area of as much as 220 mmA2 on the substrate might be used, whereas, in the embodiments of this disclosure, the amount of optically variable ink used could be reduced to just 132 mmA2, providing a difference of 66%.

[0040] FIGS 4A through 4D provide a further example of a hybrid security feature 400 according to this disclosure, wherein, through the coordinated and closely registered use of both fluorescent and optically variable inks, optically variable ink can be conserved (thereby ensuring readiness and reliability of the ability to complete large runs of security documents), additional characteristic views can be provided, and the visual effect of optically variable inks enhanced by using fluorescent ink to provide additional contrast in natural light For consistency and convenience of cross-reference, part numbers common to more than one of FIGS. 4A through 4D are numbered similarly.

[0041] Referring to the explanatory example of FIG. 4A, an image of plurality of sub-regions 405 A, 405B and 405C of UV fluorescent inks printed on a substrate 401 as they appear in natural, or visible light is shown in the figure. The properties of many UV inks, such as UV inks produced by Papierfabrik Louisenthal GmbH, which used in security document production include limited visibility (i.e., they tend to be mostly clear or faint) and miscibility with pigments. Thus, it is possible to mix one or more pigments which are visible in natural light to one or more UV inks which glow in different colors under UV light to produce a feature whose coloration and design in natural light does not telegraph its coloration under UV light. Referring to the example of FIG. 4A, a common visible-light-visible pigment (appearing as a deep purple in the original photograph) has been added to three different fluorescent inks, to create sub-regions 405A, 405B, and 405C, each of which appear to be printed in the same purple ink.

[0042] FIG. 4B is an image of sub-regions 405A through 405C, showing their appearance under UV light. As shown in the image, when viewed under UV light, sub-region 405 A glows in a first color (yellow, in the original photograph), sub-region 405B glows in a second color (green, in the original photograph), and sub-region 405 C glows in a third color (red, in the original photograph).

[0043] FIG. 4C shows sub-regions 405A-405C following printing (for example, by offset or intaglio printing) of an additional sub-region 405D of light-visible, non-fluore scent ink 405D followed by an additional sub-region 405E of optically variable ink, as the optically variable feature appears in natural light. As shown in the figure, additional sub-region 405D comprises a registered area of light-visible, non- fluorescent, non-optically variable (i.e., “normal” ink) in substantially the same color as sub-regions 405 A- 405 C, which fills in gaps between sub-regions 405A-405C to define a flower-like pattern of petals. A final sub-region 405E of optically-variable ink (for example, optically variable ink from Flex Products, Inc.) defining an abstracted vine pattern, but which is registered to overlay sub-regions 405A-405C and terminatein register with the exterior edges of the flower-like pattern of petals is printed. As FIG. 4C emphasizes, thanks to the dark color of sub-regions 405 A-C and 405D, even though sub-region 405E has delicate line weights, which do not require as much optically variable ink as solid field design (for example, security feature 200 in FIG. 2), it stands out clearly against the dark fields of sub-regions 405A-C and 405D.

[0044] FIG. 4D shows an image of sub-regions 405A-405C, 405D and 405E of optical security device 420 as they appear under UV light. As expected, sub-region 405D, formed of an ink with neither an optically-variable component nor a fluorescing component appears dark, even when exposed to light from a different range of the EM spectrum. The optically variable “sparkle” effect of sub-region 405E, remains visible, but significantly diminished (i.e., this sub-region appears more like one or more solid colors) under UV light. By contrast, sub-regions 405 A, 405B and 405 C all glow in the colors shown and described with reference to FIG. 4B.

[0045] FIGS. 5A through 5D illustrate an example of a security document 500 with a hybrid security feature 510 according to certain embodiments of this disclosure. For consistency and convenience of crossreference, part numbers common to more than two of FIGS 5 A through 5D are numbered similarly.

[0046] Skilled artisans will appreciate that harvesting, wherein a malicious actor removes authenticating components of an authentic security document to produce a counterfeit (for example, by using an authentic security feature from a lower-denomination bill to incorporate into a higher denomination counterfeit) is a perennial problem within the art. Security threads, or thin, ribbon like sections of a substrate (for example, a polymeric film) supporting one or more optically active structures (for example, holograms, or micro-lens projection systems) which are applied to, or incorporated within substrates of security documents, are, in many ways, an attractive authentication option for producers of authentic security documents. The advantages of incorporating a security feature provided on a separate structure include the fact that such structures frequently permit the use of more sophisticated optical features than can be supported on a section of paper, and security threads and other such applied security features have been in use for a long time, and are familiar to, and noticed by end-users in ways that other types of security features are not. However, one drawback of applied or integrated security threads is that, more so than many other types of security features, they are susceptible to harvesting, such as by soaking banknotes in water or bleach to loosen the adhesive bonds between paper substrate and security feature.

[0047] As shown with reference to FIGS. 5A through 5D, hybrid security features comprising mock security ribbons with both optically variable regions and fluorescent regions can provide the benefits of a familiar profile on a security document as an applied or integrated security thread, but avoid susceptibility to harvesting, because there is no separate (and thus, potentially removable) substrate supporting the security feature.

[0048] Referring to the illustrative example of FIG. 5 A, an image of a security document 500 comprising a hybrid security feature 510 printed on substrate 501 as it appears in natural, or visible light, is shown in the figure. As shown in the figure, hybrid security feature 510 comprises a set of evenly spaced rectangular (or parallelogram-shaped) blocks whose appearance mimics that of an integrated security threadwoven into or otherwise integrated with substrate 501. In this example, each rectangular block (for example, block 515) comprises a rectangular sub-region printed with an optically vanable ink, and thus the hybrid security feature 510 includes a first set of sub-regions. In natural light, each of the constituent blocks of hybrid security feature 510 provide the characteristic optical effect (for example, view dependent color changes, or characteristic “sparkle”) of the optically variable ink. In natural light, hybrid security feature 510 appears, and, depending on the print technique by which hybrid security feature 510 is applied (for example, hybrid security feature 510 can feel raised through intaglio print), and has the same tactile feel as an integrated or applied security thread.

[0049] Referring to the non-limiting example of FIG. 5B, a first mask 550 for printing a layer of a fluorescent ink is shown in the figure. In this example, mask 550 specifies that fluorescent ink be applied in a second set of sub-regions surrounding the numeric characters in blocks 555A, 555B and 555C which are registered to the constituent blocks (for example, block 515) of optically variable ink shown as being already printed on substrate 501 in FIG. 5A. In other words, fluorescent ink is provided everywhere in blocks 555A, 555B, and 555C to define the numbers shown in the mask in negative. While there is no requirement that the fluorescent ink be pigmented or pigmented a certain color, in this example, the fluorescent ink is unpigmented or pigmented in a light color configured to blend in with the blocks of optically variable ink. As such in FIG. 5B, the blocks are colored to provide contrast to make the subregions where fluorescent ink is to be applied to substrate 501 visible in the figure.

[0050] Referring to the non-limiting example of FIG. 5C, a second mask 560 for printing a layer of a second fluorescent ink is shown in the figure. As shown in the figure, the second fluorescent ink is applied in a third set of sub-regions 561 which are likewise registered to the area of the blocks defining the boundaries of hybrid security feature 510.

[0051] FIG. 5D provides an image of security document 500 as it appears under UV light. In this example, the optically variable ink is generally invisible, and overwhelmed by the fluorescent ink printed according to masks 550 and 560. As shown in the figure, hybrid optical security device 510 enhances the use of optically variable ink as an indicia of authenticity, by applying it to mimic aspects of another well- known security feature.

[0052] FIGS. 6 A through 6D illustrate additional example elements of an improved optically variable security feature according to various embodiments of this disclosure. For convenience of cross-reference, elements common to more than one of FIGS. 6A-6D are numbered similarly.

[0053] Referring to the explanatory example of FIG. 6A, a first photographic view of optically variable security feature 600 is shown. In this example, the optically variable, or hybrid, security feature 600 is disposed on a substrate 601 as the letters “CRN,” but it will be understood that any other characters, shapes, or designs could be used. As shown in FIG. 6A, the optically variable security feature 600 includes a registered combination of a first sub-region 605 and second sub-region 610, as it appears in natural, or visible light is shown in the figure. As shown in FIG. 6A, the first sub-region 605, in particular, an upper region 609, which appears to sparkle in the photograph, presents an optically variable effect - specifically,the luminescent, color changing “sparkle” characteristic of SPARK® ink. By contrast, the fluorescent mk(s) of second sub-region 610 appear flat (i.e., not glowing). Thus, optically variable security feature 600 has a first characteristic appearance - its appearance in natural, or visible light.

[0054] Based on the viewing angle or tilt of the document, the luminescent, color changing “sparkle” characteristic of the optically variable security feature 600 can shift. For example, as shown in FIG. 6B, the luminescent, color changing “sparkle” characteristic has shifted to a lower-middle region 611, due to a shift in viewing angle of the optically variable security feature 600. As another example, as shown in FIG. 6C, when the document is further tilted such that it is viewed at an extreme angle, the luminescent, color changing “sparkle” characteristic can shift to a lower region 613, due to a shift in viewing angle of the optically variable security feature 600.

[0055] Additionally, portions of the second sub-region 610 may be divided into sections via various divisions 615 using a common visible-light-visible pigment (appearing as a pale green in the original photograph) that has been added to two different fluorescent inks, such that the sections of the “CRN” design delineated by the divisions 615 each appear to be printed in the same pale green ink, but, appear in other colors when exposed to UV light. For example, the sub-region 610 of FIGS. 6A-6C is shown appearing in the same color (e.g., a pale green), but, as shown in FIG. 6D, when the optically variable security feature 600 is subjected to UV light, the different sections delineated by the divisions 615 change color, such as a first set of sections 617 changing to a first color, e.g., a bright green color, and a second set of sections 618 changing to a second color, e.g., a blue color.

[0056] As yet another example, FIGS. 7A through 7D illustrate additional example elements of an improved optically variable security feature according to various embodiments of this disclosure. For convenience of cross-reference, elements common to more than one of FIGS. 7A-7D are numbered similarly.

[0057] Referring to the explanatory example of FIG. 7A, a first photographic view of optically variable, or hybrid, security feature 700 is shown. In this example, the optically variable security feature 700 is disposed on a substrate 701 as the letters “CRN,” but it will be understood that any other characters, shapes, or designs could be used. As shown in FIG. 7A, the optically variable security feature 700 includes a registered combination of a first sub-region 705 and second sub-region 710, as it appears in natural, or visible light is shown in the figure. As shown in FIG. 7A, the first sub-region 705, in particular, an upper region 709, which appears to sparkle in the photograph, presents an optically variable effect - specifically, the luminescent, color changing “sparkle” characteristic of SPARK® ink. By contrast, the fluorescent ink(s) of second sub-region 710 appear flat (i.e., not glowing). Thus, optically variable security feature 700 has a first characteristic appearance - its appearance in natural, or visible light.

[0058] Based on the viewing angle or tilt of the document, the luminescent, color changing “sparkle” characteristic of the optically variable security feature 700 can shift. For example, as shown in FIG. 7B, the luminescent, color changing “sparkle” characteristic has shifted to a lower-middle region 711, due to a shift in viewing angle of the optically variable security feature 700. As another example, as shown in FIG. 7C,when the document is further tilted such that it is viewed at an extreme angle, the luminescent, color changing “sparkle” characteristic can shift to a lower region 713, due to a shift in viewing angle of the optically variable security feature 700. Also, the color of the luminescent, color changing “sparkle” characteristic may be different in various embodiments. For example, even when the first sub-region 705 is of a certain color (e.g., a deep purple color), the color of the luminescent, color changing “sparkle” characteristic, in some emboidments, could be a sparkling green color, whereas, in other embodiments, it could appear as a sparkling purple color.

[0059] Additionally, portions of the second sub-region 710 may be divided into sections via various divisions 715 using a common visible-light-visible pigment (appearing as a deep purple in the original photograph) that has been added to two different fluorescent inks, such that the sections of the “CRN” design delineated by the divisions 715 each appear to be printed in the same pale green ink, but, appear as other colors when exposed to UV light. For example, the sub-region 710 of FIGS. 7A-7C is shown appearing in the same color (e.g., a deep purple), but, as shown in FIG. 7D, when the optically variable security feature 700 is subjected to UV light, the different sections delineated by the divisions 715 change color, such as a first set of sections 717 changing to a first color, e.g., a green color, and a second set of sections 718 changing to a second color, e.g., a bright purple color.

[0060] In the various embodiments of this disclosure, the use of the optically variable ink in just a first sub-region, such as first sub-regions 605, 705, and use of the fluorescent ink in one or more other subregions, such as the second sub-regions 610, 710, provides for a substantial reduction in use of the optically variable ink. For example, in applications like those described with respect to FIGS. 6A-6D and 7A-7D that delineate sections of different colored, UV-revealable, such as described with respect to the sections 617, 618 and sections 717, 718, an area of as much as 220 mmA2 on the substrate might be used. However, in the embodiments of this disclosure, the amount of optically variable ink used could be reduced to just 132 mmA2, , with the fluorescent inks of different colors being used to fill in the rest of the security feature, such as 73 mmA2 of a first color, and 64 mmA2 of a second color, although it will be understood that other amounts could be used.

[0061] FIG. 8 illustrates operations of an example method 800 for creating security documents incorporating hybrid security features according to various embodiments of this disclosure. The operations described with reference to FIG. 8 are explanative, rather than limiting of the universe of embodiments according to this disclosure.

[0062] Referring to the illustrative example of FIG. 8, at operation 805, a first sub-region of an optically variable ink (optically variable inks include, without limitation, optically variable magnetic inks) is applied to a printable substrate having a flat exterior surface. The optically variable ink can be applied by lithographic printing, offset printing, intaglio printing, or jetted directly onto the substrate to form the first sub-region, which comprises at least a first area of optically variable magnetic ink, wherein the first area is bounded by a first edge.

[0063] At operation 810, a second sub-region, comprising an area of a second fluorescent ink is printed onto the substrate. The second sub-region comprises a second area that is bounded by a second edge, wherein the second edge is in register with at least a portion of the first edge. As discussed with reference to FIGS. 3A-3C, 6A-6D, and 7A-7D of this disclosure, by registering at least portions of a first edge bounding the first sub-region with portions of a second edge of the second sub-region, the functionality of the hybrid security feature is enhanced in at least two regards. First, the amount of potentially scarce optically variable ink needed for production runs is reduced, thereby addressing an ever-present need for production capacity among producers of security documents; and second, achieving good registration in print runs requires test runs and some modicum of initial material wastage for setup. For counterfeiters and malicious actors with only very limited access to optically variable inks and other supplies subject to controlled distribution, this added challenge can significantly disrupt the number of duplicate documents they can produce.

[0064] At operation 815, the printed substrate comprising the first and second sub-regions is exposed to ultraviolet light. When viewed in ultraviolet light, the optically variable ink of the first sub-region appears as one or more solid (i.e., not sparkling, or changing color in response to changes in perspective) colors, the first fluorescent ink of the second sub-region appears to glow.

[0065] Examples of security documents according to this disclosure include security documents comprising a printable substrate having a substantially flat exterior surface, a hybrid security feature disposed on the substantially flat exterior surface, the hybrid security feature comprising: a first sub-region comprising a first area of optically variable ink, the first area bounded by a first edge; and a second subregion comprising a second area of a first fluorescent ink, the second area bounded by a second edge, wherein the second edge is in register with at least a portion of the first edge, wherein the first fluorescent ink of the second sub-region glows only under ultraviolet light, wherein the hybrid security feature presents an optically variable effect characterized by: when viewed in natural light, the optically variable ink of the first sub-region presents an optically variable effect, and the first fluorescent ink of the second sub-region does not glow, and when viewed in ultraviolet light, the optically variable ink of the first sub-region appears as one or more solid colors, and the first fluorescent ink of the second sub-region glows.

[0066] Examples of security documents according to this disclosure include security documents, wherein the printable substrate is a fibrous substrate.

[0067] Examples of security documents according to this disclosure include security documents, wherein the printable substrate is a polymer substrate.

[0068] Examples of security documents according to this disclosure include security documents, wherein at least one of the first sub-region or second sub-region is an intaglio printed feature.

[0069] Examples of security documents according to this disclosure include security documents, wherein at least one of the first sub-region or second sub-region is an offset printed feature.

[0070] Examples of security documents according to this disclosure include security documents, wherein the optically variable ink comprises SPARK® security ink.

[0071] Examples of security documents according to this disclosure include security documents comprising a third sub-region comprising a third area of a second fluorescent ink, the second area bounded by a third edge, wherein the third edge is in register with at least a second portion of the first edge.

[0072] Examples of security documents according to this disclosure include security documents comprising a mock security ribbon, the mock security ribbon comprising a first plurality of parallelogram - shaped hybrid security features disposed at regular intervals along a first direction across a first side of the printable substrate, and wherein parallelogram-shaped hybrid shaped security features of the first plurality of parallelogram shaped security features have a uniform width.

[0073] Examples of security documents according to this disclosure include security documents wherein the mock security ribbon further comprises a second plurality of parallelogram shaped hybrid security features disposed at regular intervals along the first direction across a second side of the printable substrate.

[0074] Examples of security documents according to this disclosure include security documents, wherein the optically variable ink is an optically variable magnetic ink.

[0075] Examples of methods of making security documents according to this disclosure include methods comprising: on a printable substrate having a substantially flat exterior surface, forming a first subregion of a hybrid security feature comprising a first area of optically variable ink, the first area bounded by a first edge; and forming a second sub-region of the hybrid security feature comprising a second area of a first fluorescent ink, the second area bounded by a second edge, wherein the second edge is in register with at least a portion of the first edge, wherein the first fluorescent ink of the second sub-region glows only under ultraviolet light, wherein the hybrid security feature presents an optically variable effect characterized by: when viewed in natural light, the optically variable ink of the first sub-region presents an optically variable effect, and the first fluorescent ink of the second sub-region does not glow, and when viewed in ultraviolet light, the optically variable ink of the first sub-region appears as one or more solid colors, and the first fluorescent ink of the second sub-region glows.

[0076] Examples of security documents according to this disclosure include security documents, wherein the printable substrate is a fibrous substrate.

[0077] Examples of security documents according to this disclosure include security documents, wherein the printable substrate is a polymer substrate.

[0078] Examples of security documents according to this disclosure include security documents, wherein at least one of the first sub-region or second sub-region is an intaglio printed feature.

[0079] Examples of security documents according to this disclosure include security documents, wherein at least one of the first sub-region or second sub-region is an offset printed feature.

[0080] Examples of security documents according to this disclosure include security documents, wherein the optically variable ink comprises SPARK® security ink.

[0081] Examples of security documents according to this disclosure include security documents comprising forming a third sub-region comprising a third area of a second fluorescent ink, the second area bounded by a third edge, wherein the third edge is in register with at least a second portion of the first edge.

[0082] Examples of security documents according to this disclosure include security documents, wherein the hybrid security feature comprises a mock security ribbon, the mock security ribbon comprising a first plurality of parallelogram-shaped hybrid security features disposed at regular intervals along a first direction across a first side of the printable substrate, and wherein parallelogram-shaped hybrid shaped security features of the first plurality of parallelogram shaped security features have a uniform width.

[0083] Examples of security documents according to this disclosure include security documents, wherein the mock security ribbon further comprises a second plurality of parallelogram shaped hybrid security features disposed at regular intervals along the first direction across a second side of the printable substrate.

[0084] Examples of security documents according to this disclosure include security documents, wherein the optically variable ink is an optically variable magnetic ink.

[0085] Although the present disclosure has been described with various embodiments, various changes and modifications may be suggested to one skilled in the art. It is intended that the present disclosure encompass such changes and modifications as falling within the scope of the claims.

[0086] The present disclosure should not be read as implying that any particular element, step, or function is an essential element, step, or function that must be included in the scope of the claims . Moreover, the claims are not intended to invoke 35 U.S.C. § 112(f) unless the exact words “means for” are followed by a participle.

Claims

WHAT IS CLAIMED IS:

1. A security document, comprising: a printable substrate (105, 301, 401, 501, 601, 701) having a substantially flat exterior surface; and a hybrid security feature (320, 400, 510, 600, 700) disposed on the substantially flat exterior surface, the hybrid security feature comprising: a first sub-region (305, 605, 705) comprising a first area of optically variable ink, the first area bounded by a first edge; and a second sub-region (310, 405a-c, 610, 710) comprising a second area of a first fluorescent ink, the second area bounded by a second edge, wherein the second edge is in register with at least a portion of the first edge, wherein the first fluorescent ink of the second sub-region glows only under ultraviolet light, and wherein the hybrid security feature presents an optically variable effect characterized by: when viewed in natural light, the optically variable ink of the first sub-region presents an optically variable effect, and the first fluorescent ink of the second sub-region does not glow, and when viewed in ultraviolet light, the optically variable ink of the first sub-region appears as one or more solid colors, and the first fluorescent ink of the second sub-region glows.

2. The security document of claim 1, wherein the printable substrate is a fibrous substrate.

3. The security document of claim 1, wherein the printable substrate is a polymer substrate.

4. The security document of claim 1, wherein at least one of the first sub-region or second sub-region is an intaglio printed feature.

5. The security document of claim 1, wherein at least one of the first sub-region or second sub-region is an offset printed feature.

6. The security document of claim 1, wherein the optically variable ink comprises SPARK® security mk.

7. The security document of claim 1, further comprising a third sub-region (405b, 405c) comprising a third area of a second fluorescent ink, the second area bounded by a third edge, wherein the third edge is in register with at least a second portion of the first edge.

8. The security document of claim 1, further comprising a mock security ribbon, the mock security ribbon comprising a first plurality of parallelogram-shaped hybrid security features ( 10) disposed at regular intervals along a first direction across a first side of the printable substrate,wherein parallelogram-shaped hybrid shaped security features of the first plurality of parallelogram shaped security features have a uniform width.

9. The security document of claim 8, wherein the mock security ribbon further comprises a second plurality of parallelogram shaped hybrid security features (561) disposed at regular intervals along the first direction across a second side of the printable substrate.

10. The security document of claim 1 , wherein the optically variable ink is an optically variable magnetic ink.

11. A method of making a security document, the method comprising: on a printable substrate (105, 301, 401, 501, 601, 701) having a substantially flat exterior surface, forming a first sub-region (305, 605, 705) of a hybrid security feature (320, 400, 510, 600, 700) comprising a first area of optically variable ink, the first area bounded by a first edge; and forming a second sub-region (310, 405a-c, 610, 710) of the hybrid security feature comprising a second area of a first fluorescent ink, the second area bounded by a second edge, wherein the second edge is in register with at least a portion of the first edge, wherein the first fluorescent ink of the second sub-region glows only under ultraviolet light, and wherein the hybrid security feature presents an optically variable effect characterized by: when viewed in natural light, the optically variable ink of the first sub-region presents an optically variable effect, and the first fluorescent ink of the second sub-region does not glow, and when viewed in ultraviolet light, the optically variable ink of the first sub-region appears as one or more solid colors, and the first fluorescent ink of the second sub-region glows.

12. The method of claim 11, wherein the printable substrate is a fibrous substrate.

13. The method of claim 11, wherein the printable substrate is a polymer substrate.

14. The method of claim 11, wherein at least one of the first sub-region or second sub-region is an intaglio printed feature.

15. The method of claim 11, wherein at least one of the first sub-region or second sub-region is an offset printed feature.

16. The method of claim 11, wherein the optically variable ink comprises SPARK® security ink.

17. The method of claim 11, further comprising forming a third sub-region (405b, 405c) comprising a third area of a second fluorescent mk, the second area bounded by a third edge, wherein the third edge is in register with at least a second portion of the first edge.

18. The method of claim 11, wherein the hybrid security feature comprises a mock security ribbon, the mock security ribbon comprising a first plurality of parallelogram-shaped hybrid security features (510) disposed at regular intervals along a first direction across a first side of the printable substrate, and wherein parallelogram-shaped hybrid shaped security features of the first plurality of parallelogram shaped security features have a uniform width.

19. The method of claim 18, wherein the mock security ribbon further comprises a second plurality of parallelogram shaped hybrid security features (561) disposed at regular intervals along the first direction across a second side of the printable substrate.

20. The method of claim 11 , wherein the optically variable ink is an optically variable magnetic ink.

Images