Lensless Micro Optical Film

Abstract

To provide optically variable security devices, including security threads, patches, labels and strips.SOLUTION: Certain security devices according to the present disclosure utilize a lensless construction, so that multiple icon layers are coupled to produce a synthetic image or synthetic color that has an optically variable effect. Each icon layer includes an array of high-resolution icon elements that are aligned relative to each other and spaced to produce the desired optically variable effect. Such security devices are particularly, though not exclusively, useful for authenticating security documents.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present disclosure generally relates to embodiments of security devices suitable for use in authenticating (i.e., authenticating and / or protecting) valuable items that may be counterfeit, forged, tampered with, copied, and / or passed off as genuine to consumers. More specifically, certain embodiments according to the present disclosure relate to what are referred to herein as optically variable security devices (OVSDs). Certain embodiments of OVSDs according to the present disclosure are multi-layered and produce an optically variable effect (OVE) when the OVSD is viewed from varying viewpoints. The OVE is preferably a dynamic effect, where a change in viewpoint results in a change in the position, size, shape, or color of the image projected by the OVSD. OVSDs according to various embodiments of the present disclosure have particular utility in authenticating valuable items such as security documents (e.g., currency documents, identification documents) and high-value consumer products. [Background technology]

[0002] Suppliers of authentic valuable products often struggle with counterfeiters, who create imitation versions of authenticating products using cheaper processes and attempt to pass these counterfeits off to unsuspecting consumers as authentic versions. For example, counterfeiters often produce counterfeit security documents by copying authentic security documents using sophisticated printing and copying techniques and then pass the counterfeits off as authentic documents. Some consumer products do not rely on security labels for authentication, in which case counterfeiters simply replicate the consumer product and pass it off as authentic. However, some consumer products use security labels to authenticate the consumer product, in which case counterfeiters must replicate the consumer product, including the security label.

[0003] To thwart the efforts of counterfeiters, certain manufacturers of authentic valuables utilize security devices that display optically variable images. These devices have become useful tools in combating counterfeit and imitation goods, as even the most sophisticated copying and printing techniques cannot reproduce the optical variability produced by these security devices.

[0004] There are several types of optical security devices. For example, U.S. Patents US7,333,268, US7,738,175, and US7,468,842 to Steenblik et al. describe one or more optical security devices that generate a composite image when an array of image elements is viewed through an array of focusing elements. These composite images may exhibit optical variability by exhibiting several different optical effects (e.g., changes in position, color, size, shape, number, etc.) when viewed from different viewpoints. Material structures capable of exhibiting such effects are also described in U.S. Patent US7,738,175 to Steenblik et al., U.S. Patent US7,830,627 to Commander et al., U.S. Patent US8,149,511 to Kaule et al., U.S. Patent US8,878,844 to Kaule et al., U.S. Patent US8,786,521 to Kaule et al., European Patent Application No. EP2,162,294 to Kaule et al., and European Patent Application No. EP2,164,713 to Kaule.

[0005] While several optical security devices exist that are suitable for providing enhanced security and authentication to a variety of high-security or high-value products, opportunities remain to enhance the performance and functionality of optical security devices. For example, devices such as those described in the references listed above often require multiple manufacturing steps to create separate image and focusing layers. This can be expensive and can introduce variability into the manufacturing process. Furthermore, the optical security devices described above may require precise post-manufacturing alignment between the array of focusing elements and the array of icon elements, further complicating the process. Optical security devices are often lens-based systems that include an array of lenses as the focusing elements of the focusing layer. Lenses are susceptible to contamination, which can distort or interfere with the composite image generated by the security device.

[0006] One alternative lens-based security device is disclosed in Australian Patent Application No. AU2017101291 (the "'291 Application"). Disclosed therein is a device having at least two layers: a first layer including a first pattern and a second layer having a second pattern. The second layer is spaced a fixed distance from the first layer, and the second pattern includes at least one discrete region that is a scaled version of a corresponding region in the first pattern. The device is said to produce a three-dimensional visual effect when the device is viewed due to Moiré interference. This Moiré interference effect is generated from global scaling, in which both the size of the lines or dots and their spacing are enlarged or reduced in one layer relative to the other.

[0007] The device described in the '291 application has its own drawbacks. In particular, the lines or dots are low-resolution lines printed or embossed using a conventional printing press, such as a Simultane press. The resolution of any image projected by the device is limited by the lack of high-resolution lines or dots. This becomes important when the thickness of the device is critical to the authentication of valuable items, such as when the device is used to authenticate security documents (e.g., banknotes, etc.). Summary of the Invention

[0008] Certain embodiments according to the present disclosure include one or more of: (i) a security device; (ii) a method of making a security device; (iii) a use of or a method of using a security device; (iv) a valuable item including a security device; or (v) a product of the process that includes a security device manufactured by the methods described herein.

[0009] In one aspect, a security device is provided, and in some embodiments the security device is an optically variable security device (OVSD) that includes: (i) a first icon layer having a first array of icon elements; and (ii) a second icon layer coupled to the first icon layer and having a second array of icon elements, wherein the icon elements of the first icon layer and the second icon layer are lines, dots, or a combination thereof, and the icon elements are high-resolution icon elements.

[0010] In another aspect, a method of making an OVSD is provided, and in certain embodiments, the method includes: (i) providing an optical spacer layer; (ii) forming a first icon layer on a first side of the optical spacer layer and a second icon layer on a second, opposing side of the optical spacer; and (iii) forming an array of icon elements on or in the first icon layer and a second array of icon elements on or in the second icon layer, wherein the icon elements are high-resolution icon elements.

[0011] In another aspect, a method of authenticating a valuable item is provided, which in some embodiments includes coupling an OVSD to the valuable item as described herein. Other technical features may be readily apparent to those skilled in the art from the following figures, description, and claims.

[0012] In another aspect, a valuable item is provided, and in various embodiments, the valuable item includes (i) an OVSD described herein, and (ii) a substrate interface, where the OVSD is bonded to the substrate interface. In certain embodiments according to the present disclosure, the valuable item is a banknote and includes (i) a substrate layer having a first side and an opposing second side, (ii) a first icon layer having a first array of icon elements, and (iii) a second icon layer having a second array of icon elements, where the icon elements are high-resolution icon elements.

[0013] In another aspect, embodiments according to the present disclosure include products of the processes, the products being valuables according to various embodiments of the present disclosure made by processes according to some embodiments of the present disclosure.

[0014] According to various embodiments of the present disclosure, an OVSD includes an OVSD according to one or more embodiments of the present disclosure and a substrate interface, wherein the OVSD is coupled to a valuable item via the substrate interface. In some embodiments, the valuable item is a banknote including: (i) a substrate layer having a first side and an opposing second side; (ii) a first icon layer having a first array of icon elements partially filled with a transparent material; and (iii) a second icon layer having a second array of icon elements, wherein the icon elements are high-resolution icon elements in the form of filled posts.

[0015] Embodiments according to the present disclosure are further described herein to enable those skilled in the art (hereinafter "PHOSITA") to make and use the same without resorting to undue experimentation. Accordingly, in this disclosure, the embodiments described above or below are not intended to limit the scope of the embodiments disclosed and claimed herein, but are to be construed merely as exemplary embodiments provided for the purpose of illustrating particular embodiments. It should be apparent to PHOSITA that many more modifications and embodiments, in addition to those explicitly described herein, are possible without departing from the inventive concepts herein. In particular, the terms "comprises," "having," and "comprising" should be construed as referring to elements, components, or steps in a non-exclusive manner, indicating that a referenced element, component, or step may be present, utilized, or combined with other elements, components, or steps not expressly mentioned or specifically combined with other embodiments described herein.

[0016] In interpreting the terms used in this instant disclosure, it should be noted that as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0017] All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and / or materials in connection with which the publications are cited. The publications mentioned herein are provided solely for their disclosure.

[0018] Before embarking on the Detailed Description below, it may be convenient to provide definitions of certain words and phrases used throughout this patent specification. The term "couple" and its derivatives refer to direct or indirect communication between two or more elements, regardless of whether they are in physical contact with one another. The terms "include" and "comprise," and their derivatives, mean open-ended inclusion. The term "or" is inclusive and / or. The phrase "associated" and its derivatives mean include, comprise, interconnect, contain, be contained, connect to or with, couple to or with, communicate with, cooperate with, interleave, juxtapose, be adjacent to, be bound to or with, have, have the characteristic of, have a relationship with, and the like. The phrase "at least one," when used in conjunction with a list of items, means that different combinations of one or more of the listed items may be used, and that only one item in the list may be required. For example, "at least one of A, B, and C" includes any of the combinations of A, B, C, A and B, A and C, B and C, and A, B, and C.

[0019] Definitions of certain other words and phrases are provided throughout this patent specification, and those skilled in the art should understand many, if not most, of them, and should understand that these definitions apply to both previous and future uses of those defined words and phrases.

[0020] 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 and in which: [Brief explanation of the drawings]

[0021] [Figure 1]10A-10C show cross-sectional views of an OVSD that provides an OVE without filling or coating icon elements, according to various embodiments of the present disclosure. [Figure 2] 1A-1C show cross-sectional views of an OVSD resulting in an OVE coated with icon elements of first and second icon layers according to some embodiments of the present disclosure. [Figure 3] 10A illustrates a cross-sectional view of an OVSD resulting in an OVE filled with icon elements of a second icon layer, according to certain embodiments of the present disclosure. [Figure 4] 1A-1C show cross-sectional views of an OVSD resulting in an OVE in which the icon elements of a first icon layer are filled and the icon elements of a second icon layer are coated, according to some embodiments of the present disclosure. [Figure 5] 10A-10C show cross-sectional views of an OVSD resulting in an OVE without separate optical spacers and without filled or coated icon elements, according to various embodiments of the present disclosure. [Figure 6] 1 illustrates a cross-sectional view of an OVSD resulting in an OVE with embedded icon elements of first and second icon layers, according to certain embodiments of the present disclosure. [Figure 7] 1A-1C illustrate cross-sectional views of an OVSD resulting in an OVE in which the icon elements of the first icon layer are coated or filled posts and the icon elements of the second icon layer are filled voids, according to various embodiments of the present disclosure. [Figure 8] FIG. 10 shows a cross-sectional view of an OVSD resulting in an OVE in which the icon elements of the first icon layer are coated or filled posts and the icon elements of the second icon layer are coated posts, according to certain embodiments of the present disclosure. [Figure 9] 1A-1C illustrate cross-sectional views of an OVSD resulting in an OVE including icon elements of a first icon layer that are coated and icon elements of a second icon layer that are filled posts, according to some embodiments of the present disclosure. [Figure 10]1 illustrates an isometric cross-sectional view of an OVSD including first and second icon layers including coated icon elements, resulting in an OVE in the form of a rolling bar, according to certain embodiments of the present disclosure. [Figure 11] 1 illustrates an isometric cross-sectional view of an OVSD on a banknote including a rolling bar OVE, according to some embodiments of the present disclosure. [Figure 12] 1A-1C illustrate cross-sectional views of an OVSD in which a first icon layer includes filled posts, a second icon layer is partially filled with a second transparent material, and the areas between the posts are only partially filled, according to various embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0022] definition The terms "coat" or "coating" as used herein with respect to contrast material encompass application of the contrast material to the voids such that the contrast material within the voids occupies less than 50% of the depth of the voids. According to certain embodiments, the "coat" or "coating" follows the shape of the boundaries of the voids, including the base and optionally the sidewalls. When used as a transitive verb herein, "coat" or "coating" encompasses applying a coat to posts or solid areas between voids.

[0023] As used herein, the term "contrast material" encompasses materials that, when incorporated as part of the icon layer, create a visible distinction between the icon element and the surrounding / adjacent materials.

[0024] As used herein, the term "dimensional deviation" encompasses differences in one or more of size, shape, or local angle between icon elements of a first array of icon elements and icon elements of a second array of icon elements.

[0025] The terms "fill" or "filling" as used herein with respect to contrast material encompass applying the contrast material to a void or printing posts with the contrast material such that the contrast material within the void occupies 50% or more of the depth of the void.

[0026] The term "high resolution" as used herein with respect to an icon element or set of icon elements includes at least one of: (i) lines and / or dots having widths ranging from 0.5 μm to about 6.5 μm, or (ii) lines and / or dots having spacing of less than 7.7 μm.

[0027] The terms "hole" or "through-hole" as used herein with respect to voids encompass structures or regions of the OVSD that extend from one side of a layer of the OVSD to at least another side of that layer (e.g., a first icon layer, a second icon layer, or an optical spacer).

[0028] The term "mesa" as used herein with respect to posts includes posts that are taller than they are wide (ie, extensions from their base).

[0029] As used herein, the term "optically variable effect" or "OVE" encompasses the display or projection of an image or set of images, such as a composite image, that changes at least one of position, size, shape, or color when the optically variable security device is viewed from varying viewpoints.

[0030] As used herein, the term "periodic offset" encompasses a difference in the period of an array of icon elements present in one of a first array of icon elements relative to a second array of icon elements.

[0031] The term "plateau" as used herein with respect to posts encompasses posts whose bases are wider than their heights (ie, extensions from the first icon layer or second icon layer).

[0032] The term "protrusions" as used herein with respect to posts includes posts that have sides that are not parallel to one another or that have tops that are not parallel to their bases.

[0033] The term "depression" as used herein with respect to a void encompasses a region of an OVSD having a depth that terminates within the thickness of the layer in which it is formed.

[0034] As used herein, the term "rotational misalignment" encompasses a difference in angular orientation of one repeating pattern of a first array of icon elements relative to one repeating pattern of a second array of icon elements.

[0035] As used herein, the term "spacing dimension" encompasses measurements of the area (e.g., gap) between successive icon elements, such as between two lines, two dots, or a line and a dot, that form an array of icon elements, or a portion thereof.

[0036] As used herein, the term "composite color" encompasses a color or set of colors projected by an OVSD, where the projected color is from an icon element or set of icon elements that have pigments of different colors than the color(s) being projected, or from icon element(s) that have no pigments or colors.

[0037] As used herein, the term "composite image" encompasses an image or set of images projected by an OVSD, where the projected image is generated from icon elements, a set of icon elements, or portions of icon elements in an icon layer that are either (i) not observable by a human without visual aid, such as a magnifying tool or another overlaid icon layer, or (ii) where the image provided by the icon element(s) of an icon layer differs from the projected image, such as when portions of the icon elements are combined to form the projected image.

[0038] As used herein, the term "void" encompasses depressions or holes formed in a material layer (eg, the first icon layer, the second icon layer, or the optical spacer layer) of the OVSD.

[0039] As used herein, the term "width dimension" encompasses the width across an icon element, such as the width of a line or the width of a dot.

[0040] As used herein, the term "zonal offset" encompasses differences in dimensional, rotational or periodic offset in one localized region of a first array of icon elements relative to a second array of icon elements.

[0041] To date, there remains a need for security devices that can be prepared using lensless systems to avoid at least some of the deficiencies identified above. Additionally, there remains a need for security devices that can be manufactured with high-resolution icon elements, thereby making them much more difficult for counterfeiters to replicate while also producing high-resolution images. Additionally, there remains a need for security devices that can reduce the alignment constraints required for conventional optical security devices. The inventors have surprisingly discovered that this objective can be at least partially advanced through certain embodiments according to the present disclosure.

[0042] According to various embodiments of the present disclosure, an OVSD includes a first icon layer having a first array of icon elements and a second icon layer coupled to the first icon layer and having a second array of icon elements, the first icon layer and the second icon layer being oriented toward each other such that a composite image or composite color is produced when the OVSD is viewed through at least one of the first icon layer and the second icon layer.

[0043] Various types of icon elements are considered suitable embodiments of an OVSD. In some embodiments, the icon elements include (elongated) lines or dots, or a combination thereof. References herein to lines or dots encompass embodiments that contemplate the lines or dots being crafted into any shape or combination of shapes. For example, lines may form triangles, rectangles, trapezoids, diamonds, donuts, ellipses, or combinations thereof, including complex shapes composed of a collection of more basic shapes. The lines or dots may be arranged into a preferred pattern or into a preferred indicia (such as letters, numbers, symbols, etc.). For example, in some embodiments, the lines or dots are arranged into a shape into one of the first or second icon layers, such that when viewed through the second icon layer, the OVSD projects a rolling bar having an optically variable effect (OVE). Various exemplary OVEs are discussed further herein.

[0044] OVSDs according to various embodiments of the present disclosure employ high-resolution icon elements. In certain embodiments according to the present disclosure, the resolution of the icon elements is finer than these conventional printing techniques. In fact, in various embodiments, the resolution is such that indicia printed at the resolution of the icon elements of the present invention are imperceptible to the naked eye. However, it has been surprisingly discovered that icon elements in at least one of the first or second icon layers can be formed at high resolution while still being perceptible in the form of an OVE when viewed through the other icon layer. In certain embodiments according to the present disclosure, all icon elements are high-resolution icon elements. In certain embodiments, only a portion of the icon elements are high-resolution icon elements, for example, in embodiments where high-resolution and low-resolution icon elements are arranged to provide specific pattern(s). In various embodiments, the icon elements in both the first and second icon layers are high-resolution icon elements. In one embodiment, the icon elements in one of the first and second icon layers are high-resolution. In some embodiments according to the present disclosure, at least one icon element of the first array of icon elements and the second array of icon elements has a width (line or dot) dimension in the range of about 0.5 μm to about 6.5 μm or an inter-icon element spacing dimension of less than 7.7 μm.

[0045] In various embodiments according to the present disclosure, high resolution is provided by line widths ranging from about 0.5 μm to about 6.5 μm. According to certain embodiments, the line width is from about 0.5 μm to about 5 μm.

[0046] In various embodiments, high resolution is provided by a line spacing of less than 7.7 μm. According to some embodiments, the line spacing is between about 0.5 μm and about 5.5 μm.

[0047] According to certain embodiments, high resolution is provided by dot widths ranging in size from about 0.5 μm to about 6.5 μm, hi some embodiments, the dot width is from 0.5 μm to about 5 μm.

[0048] In at least one embodiment, high resolution of the icon elements is provided by a line / dot pitch ranging from about 1.0 μm to about 6.5 μm. According to certain embodiments, the line / dot pitch ranges from about 1.0 μm to about 4.0 μm. Notably, the variability in line / dot pitch is not limited to discrete areas in some embodiments.

[0049] In at least one embodiment, high resolution is provided by a dot spacing of less than 7.7 μm. In various embodiments, the spacing is from about 0.5 μm to about 5.5 μm.

[0050] In certain embodiments, the OVSD is a lensless system and therefore does not require microlenses or lenticular lenses to generate a composite image or color. In particular, an OVSD according to various embodiments of the present disclosure does not require a lens system to generate a composite image or color in the OVE.

[0051] In certain embodiments according to the present disclosure, the first array of icon elements in the first icon layer and the second array of icon elements in the second icon layer are oriented toward one another so that they provide a composite image with an optically variable effect (OVE). For example, in some embodiments, the composite image with the OVE generated by the OVSD includes a rolling bar. In at least one embodiment, the composite image with the OVE includes a multicolored rolling bar. In various embodiments, the OVE is a color switch, whereby at least a portion of the composite image changes from one color to another as the OVSD is tilted relative to a generally static point of view (e.g., the observer's eyeball). In certain embodiments, the OVE includes a composite color formed as a combination of colors seen in the icon layer of the OVSD. In certain embodiments according to the present disclosure, the first and second icon layers are combined to generate a variable composite image including the rolling bar, such that the rolling bar appears to move as the observer's point of view (POV) changes relative to the OVSD. The OVE of the rolling bar according to certain embodiments of the present disclosure includes at least two sets of bars interleaved with each other.

[0052] In certain embodiments according to the present disclosure, the OVSD provides a color-switching OVE, where the color of the composite image, or portions thereof, changes from one color to another when the OVSD is viewed from different angles. For example, in certain embodiments according to the present disclosure, a first array of icon elements includes voids filled or coated with a first color (e.g., black pigment), and a second array of icon elements includes empty voids. Viewing the OVSD from the side closer to the second array of icon elements provides a rolling bar OVE, where the full set of bars is comprised of multiple sets of alternating bars, with the first set of bars having individual bars interspersed alternately among the second set of rolling bars. The first set of rolling bars provides a first color, and the second set of bars provides a second color. Tilting the device to change viewpoints causes the colors in each set to change. As one non-limiting example, in at least one embodiment, the first set of rolling bars provides a native blue color, and the second set of bars provides a native green color. As the OVSD is tilted, the original blue color of the first set of rolling bars changes to OVE green, and the original green color changes to OVE blue. Of course, in the context of this application, it should be understood that the first color need not be switched to a second color, but rather the second color can be switched to the first color, as multiple color changes are facilitated by changing the pattern of icon elements in at least one of the first and second icon layers. While the color switch is described in connection with a composite image including a rolling bar, it should be understood that the composite image may take on different patterns depending on the arrangement of the icon elements, and thus the color switch may also be applied to different patterns of those composite images. In at least one embodiment, the first set of rolling bars changes from blue to green. According to certain embodiments, the observed color shift provided as part of the OVE manifests itself due to interference created by light transmitted and reflected by a thin layer of OVSD, causing it to act as a thin-film optical filter. Varying thicknesses of the material translate to different colors. As the OVSD material is tilted, the optical path length of the light relative to the viewer's eye also changes, changing the wavelengths affected by the filter and thereby causing the color to change.In another embodiment, the first set of rolling bars includes a border bar having a border color. When the POV is changed, the border colors of the border bar, the first set of rolling bars, and the second set of rolling bars each change from a first color to a second color. In certain embodiments according to the present disclosure, the OVSD projects a composite color, and the composite image has a color that is distinguishable from the pigment used to fill, coat, or print the icon elements. For example, in one particular embodiment, the icon elements are filled or coated with a yellow pigment, but the composite image is projected in yellow and / or green, thereby generating the composite color. Depending on the relative placement of the first and second icon layers, the spacing between the layers, and the size distribution / placement of the icon elements, other composite colors or color combinations can also be generated.

[0053] In certain embodiments according to the present disclosure, the OVSD provides a rolling bar OVE, in which a first array of icon elements and a second array of icon elements are combined to provide a set of rolling bars. The first set of rolling bars are interspersed with a second set of rolling bars. When the POV of the OVSD changes, such as by tilting, both sets of rolling bars appear to change position or switch positions. It should be understood that the OVE provided by embodiments according to the present disclosure is not limited to rolling bars, and the OVE generated by a change in viewpoint is not limited to movement in a particular direction. For example, a first set of composite images (e.g., rolling bars) may move in a first direction, while another set moves in a different direction. In certain embodiments according to the present disclosure, the rolling bars move with orthoparallax movement (i.e., perpendicular to the tilt direction). For example, the rolling bars can move in any direction in response to changes in the viewer's viewpoint. For example, in certain embodiments according to the present disclosure, lines are used in one of the layers, and then the material acts as a lenticular material (for design / movement purposes) and moves only along one direction of tilt. However, the relative pitch / angle of the lines in the second layer can be adjusted to direct the motion of the moiré lines in different directions.

[0054] As described above, in certain embodiments according to the present disclosure, the OVSD produces a composite color OVE. As used herein, composite color encompasses image colors projected from a colorant material forming part of one of the first array of icon elements or the second array of icon elements, where the projected image color includes at least one color that is different from the color of the colorant material found in the array of icon elements. In a preferred embodiment, the array of icon elements is filled or coated with a dark pigment, which produces a first set of multicolored bars that are green bars with a yellow border and a second set of blue bars interspersed among the first set. Adjusting the spacing between the first and second icon layers results in different color sets for the rolling bars and their corresponding border regions. In certain embodiments according to the present disclosure, the rolling bars do not have distinct border regions, or the border regions are the same color as the rolling bars to which they are connected.

[0055] According to certain embodiments, various icon elements are described in PCT / US2004 / 039315 to Steenblik et al., which is incorporated herein by reference. It is contemplated herein that the icon elements can be voids, posts, or a combination thereof. In certain embodiments according to the present disclosure, the voids have parallel sides and do not taper from either side of the layer in which they are formed. In certain embodiments according to the present disclosure, the voids have non-parallel sides and taper from at least one side of the layer to the other. In some embodiments, the taper is from the outer layer to the inner layer. The icon elements can be formed by various methods, including, for example, laser patterning, photolithography, machining, embossing, printing, injection molding, other molding techniques, or any combination thereof. In various embodiments, the voids or posts are formed in the icon layer by applying an embossing tool containing a predetermined pattern of void-forming elements. In one or more embodiments, the icon layer, when embossed, is an uncured polymeric formulation. The icon layer is then cured, and the embossing tool is removed. In various embodiments according to the present disclosure, the voids are then filled with a contrasting material, such as a pigment or a reflective material (e.g., a reflective metal, alloy, etc.). As used herein, the term void encompasses depressions and holes. According to various embodiments according to the present disclosure, holes extend through at least one layer of the OVSD, while according to some embodiments, depressions begin and end within a single layer of the OVSD. At least two icon layers can be formed simultaneously or sequentially and then bonded together. For example, in certain embodiments according to the present disclosure, a first preliminary icon layer is layered on top of a second preliminary icon layer. As used in this disclosure, the term "preliminary" encompasses the indication that the icon layers lack the icon elements necessary to form a composite image or color. After the preliminary (in some embodiments, polymeric) icon layers are layered together to form a preliminary composite icon laminate, an embossing tool is contacted with opposing surfaces of the composite icon laminate.It has been found that alignment of a first icon layer to a second icon layer can be improved by simultaneous embossing. Nevertheless, it is contemplated herein that the first icon layer may be embossed before the second icon layer, or vice versa. In some embodiments, the icon elements may take various shapes, such as lines and dots, that are themselves specific indicia and / or are arranged in an indicia pattern. The voids may be coated by various methods, including, for example, electroplating, electroless plating, vapor deposition (e.g., chemical vapor deposition or physical vapor deposition), monomer vapor deposition, sputtering, spin coating, roll coating, other coating methods, and any combination thereof.

[0056] In certain embodiments according to the present disclosure, the icon elements include posts formed on or within a layer of OVSD. In certain embodiments according to the present disclosure, the posts are formed using an embossing or printing tool capable of transferring a contrasting material to the surface of the OVSD substrate layer. In certain embodiments according to the present disclosure, the posts are formed using a printing tool that provides high-resolution lines or dots. It is contemplated within the scope of the present disclosure that the posts may take a variety of shapes. However, it has been presently discovered that preferred shapes are plateaus, protrusions, or mesas.

[0057] The OVE or composite color may be viewed by viewing the OVSD from either side of the OVSD, such as from the side closer to the first icon layer, or from the side closer to the second icon layer, or from both sides of the OVSD. In certain embodiments according to the present disclosure, the OVE is viewable from one of the icon layers. In certain embodiments according to the present disclosure, the OVE is viewable from both the first icon layer and the second icon layer. For polymer banknotes, it has been found useful for the OVE of the OVSD to be viewable from either side of the OVSD. In certain embodiments, the composite image or composite color is viewable from both sides even if only one side has filled / coated icon elements, although it is preferred that the first and second icon layers are equally filled / coated with icon elements. In some embodiments, the composite image is formed from interference caused by the icon layer closest to the viewer. This interference can be provided by either or both of the icon layers being filled, coated, empty, or any combination thereof. For example, in certain embodiments according to the present disclosure, a first icon layer closer to the viewer has icon elements that are empty voids, while a second icon layer further from the viewer has icon elements that are filled voids. Aligning the first icon layer with the second icon layer creates two sets of interspersed rolling bars that change color as the OVSD tilts or the viewer's viewpoint changes. In various embodiments, both the first and second icon layers are provided with icon elements that are either partially filled or coated. Adjustments to alignment and / or spacing can produce a desired OVE. Adjustments to the spacing, repeat period, or patterning of the icon elements can be performed in some embodiments by tuning the system to produce a desired OVE.

[0058] In embodiments according to the present disclosure, it is contemplated that the bonding of the first icon layer to the second icon layer can be direct or indirect. In certain embodiments according to the present disclosure, the first icon layer and the second icon layer are bonded to one another such that the OVSD provides at least one optically variable effect when viewed from at least one side of the OVSD. However, in certain embodiments, an additional component or layer is disposed between the first icon layer and the second icon layer. While direct bonding of the first and second icon layers is preferred, in such embodiments the resulting OVSD may be thinner, and therefore in certain embodiments a separate optical spacer layer is disposed between the first icon layer and the second icon layer. Preferably, the icon layer and the optical spacer have the same transparency or translucency and refractive index. However, in certain embodiments, the icon layer and / or the spacer layer comprise distinct material formulations. Alternatively, it is contemplated that additional layers may be disposed on one or more exterior surfaces of the composite icon structure.

[0059] According to certain embodiments, the OVSD is constructed so that the first icon layer is composed of filled posts, while the second layer remains unfilled. In some embodiments, the clarity and contrast of the composite image can be further enhanced by adding a transparent material applied to partially fill the spaces between the posts of the second icon layer. This material can be an additive applied during the manufacturing stage of the OVSD, such as a transparent thread adhesive, or it can also be a liquid polymer applied during the papermaking stage of the process. Examples of suitable transparent materials include, but are not limited to, polyvinyl alcohol, gelatin, or polyurethane.

[0060] According to certain embodiments, at least one of the first and second icon layers functions as an interference layer. In at least one embodiment, the first icon layer, which is closest to the viewer, is empty or contains icon elements filled in a different pattern than the second icon layer, while the second icon layer, which is distal to the viewer, contains icon elements that are posts of a contrasting material. The interference caused by the first layer results in an OVSD when viewed from varying perspectives. It should be understood, therefore, that the icon elements in the first and second icon layers may be the same, different, or the same but filled / coated differently or in the same way. In this exemplary example, the first icon layer contained voids and the second icon layer contained posts, but the reverse is also within the scope of this disclosure.

[0061] Suitable icon elements and methods for providing them are described in International Patent Applications WO2005 / 052650, WO2006 / 125224, WO2008 / 008635, WO2011 / 019912, WO2011 / 163298, WO2013 / 028534, WO2014 / 143980, WO2009 / 017824, WO20 Nos. 16 / 044372, ...

[0062] The relief structures forming the pictorial icon elements may be of various sizes, including micro-sized, nano-sized, macro-sized, or any combination thereof, depending on the embodiment. While nano-sized or macro-sized are considered suitable, it is preferred that micro-sized pictorial icon elements be used. The inventors have found that certain embodiments utilizing micro-sized pictorial icon elements exhibit relatively good manufacturability.

[0063] In certain embodiments according to the present disclosure, the OVSD includes an optical spacer, with the first and second icon layers integrated on opposing sides of the optical spacer. Various optical spacers will be apparent to those skilled in the art in light of the present disclosure. Thus, as the thickness of the optical spacer increases, the bars appear to switch or roll faster as the viewpoint is changed, for example, by tilting the OVSD, as described in certain embodiments. According to various embodiments, the OVSD has a thickness of 50 μm or less (including less than 45 μm, 40 μm, and 35 μm). Surprisingly, we have discovered that the OVE can be recognized even at thicknesses of less than 30 μm. This is particularly observable in embodiments where the OVE can be recognized from both sides of the OVSD. The interference is particularly enhanced by the presence of contrast material in both the first and second icon layers, resulting in a surprising enhancement of the OVE.

[0064] Similarly, in various embodiments of OVSDs according to the present disclosure, additional components / layers include, but are not limited to, optical spacers, coating layers, tie layers, master liner framing layers, patterned metal layers, reflective layers, opacifying layers, vapor deposition layers, color-shifting structural layers, anti-fouling layers, hardened layers, or colored or dyed layers. Multiple arrays of micro-image elements or image icon elements are also contemplated as part of an image projection system. Similarly, one or more additional icon layers are also contemplated as being disposed between the first and second icon layers. Surprisingly, it has been discovered that using two icon layers without a lens layer can avoid the need for a sealing layer, although it should be understood that a sealing layer is still contemplated in embodiments according to the present disclosure including OVSDs in which at least one of the first or second icon layers is partially or completely sealed. For example, in certain embodiments, the sealing layer occupies a void, particularly if the void has empty space, while in other embodiments, the sealing layer covers only the top surface of at least one of the first and second icon layers. In other embodiments, the sealing layer covers the entire OVSD.

[0065] In certain embodiments, the composite image projected by the OVSD is due to the offset of the first array of icon elements relative to the second array of icon elements. In certain embodiments according to the present disclosure, such offset between the two arrays produces a moiré image.

[0066] In certain embodiments according to the present disclosure, the misalignment results from at least one of dimensional misalignment, rotational misalignment, periodic misalignment, or zonal misalignment. In certain embodiments according to the present disclosure, the icon elements of the first icon layer are substantially uniform but differ in size relative to the icon elements of the second icon layer, thereby resulting in dimensional misalignment. Such dimensional misalignment can also be provided by varying the size of the icon elements throughout the first icon layer in a pattern that differs from the pattern of size variations present in the icon elements of the second icon layer. In certain embodiments according to the present disclosure, cyclic misalignment is provided whereby the icon elements are uniformly spaced in the first icon layer but arranged at a different spacing than that provided in the second icon layer. Alternatively, the spacing of the icon elements can be non-uniform in the first icon layer, but the pattern differs from the spacing pattern of the icon elements of the second icon layer, thereby resulting in cyclic misalignment. In certain embodiments according to the present disclosure, zonal misalignment encompasses a first icon layer having icon elements present in a particular zone of the first icon layer, with the corresponding zone of the second icon layer being a zone of icon elements having a different size, shape, or spacing.

[0067] In certain embodiments according to the present disclosure, the icon layer may be incorporated with a contrasting material. In at least one embodiment, the voids are filled or coated with a contrasting material. In some embodiments, some icon elements are filled while others are coated, such that an array of icon elements includes both filled and coated icon elements. In certain embodiments according to the present disclosure, the icon elements are voids coated with a contrasting material, such that less than 50% of the void depth is occupied by the contrasting material. Preferably, the material occupies less than 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, and 5% of the void depth and takes the shape of the void's boundaries, including the base and sidewalls. In certain embodiments according to the present disclosure, the icon elements are voids filled with a contrasting material, such that 50% or more of the void depth is occupied by the contrasting material. Preferably, more than 60%, 70%, 80%, 90%, 95%, and 99% of the void depth is occupied by the contrasting material. The voids can be filled with any suitable contrasting material, such as a pigmented resin, ink, dye, metal, or magnetic material. In an exemplary embodiment, the voids are filled with a pigmented resin containing submicron pigments available from Sun Chemical Corporation under the product name Spectra Pac.

[0068] In certain embodiments according to the present disclosure, the posts are printed with or coated with a contrasting material. Printing of the posts, as referred to herein, refers to the posts being formed by some printing means, which provides the posts with high resolution, or the posts being formed as solid regions of a relief structure by some high-resolution embossing process. If the posts are formed by a printing process, it is preferred that the contrasting material be included in the printing medium (e.g., ink), thereby filling the posts. Alternatively, if the posts are formed by an embossing process, it is preferred that the contrasting material be applied through a coating that coats the exposed sides of the posts.

[0069] In certain embodiments according to the present disclosure, both the first and second icon layers include icon elements that are posts and / or voids. In certain embodiments according to the present disclosure, one of the first arrays of icon elements includes posts and the second array of icon elements includes voids. The voids or posts may be filled or coated as described above.

[0070] It has been unexpectedly discovered that certain embodiments according to the present disclosure enable the use of high-resolution icon tools to form both a first icon layer and a second icon layer, which, when superimposed, result in an OVE. It has previously been understood that high-resolution icon tools present alignment challenges for lens-based systems. Surprisingly, an OVSD including both high-resolution icon layers according to embodiments of the present disclosure not only provides improved alignment, but also enables composite image and color projection and OVE.

[0071] Certain embodiments according to the present disclosure provide for the use of the OVSD disclosed herein to authenticate valuable items. In certain embodiments according to the present disclosure, the OVSD is bonded to a product, thereby providing an OVE using high-resolution icon elements. The OVSD can be bonded to a valuable item via various adhesives, as will be apparent to those skilled in the art in light of the present disclosure. For example, a suitable means for bonding the OVSD to a banknote substrate may be via a heat-activated or water-activated adhesive. Additionally or alternatively, the OVSD may be woven into the paper during the manufacture of the banknote substrate, thereby being fully or partially embedded (e.g., in a window). In another embodiment, the banknote substrate is made of a polymer, and the OVSD is bonded to at least one side of the banknote substrate. Alternatively, in certain embodiments according to the present disclosure, the polymer banknote substrate functions as an optical spacer, with a first icon layer disposed on a first side of the substrate and a second icon layer disposed on a second side of the substrate. In certain embodiments according to the present disclosure, the OVSD functions as a polymer in a window in the paper substrate. It is also contemplated that the OVSD may be bonded to substrates other than those used for banknotes. For example, in certain embodiments according to the present disclosure, the OVSD is coupled to a security label used to authenticate a consumer product. The OVSD may be coupled to a label such as those described herein for security documents (e.g., banknotes).

[0072] Various embodiments according to the present disclosure include methods of fabricating an OVSD as disclosed herein. In certain embodiments according to the present disclosure, the method includes providing an optical spacer layer, forming a first icon layer on a first side of the optical spacer layer as described herein, similarly forming a second icon layer on a second, opposing side of the optical spacer, forming an array of icon elements on or within the first icon layer, and forming a second array of icon elements on or within the second icon layer, wherein the icon elements are high-resolution icon elements. Preferably, the first and second arrays of icon elements are formed simultaneously. However, in certain embodiments according to the present disclosure in which the icon elements are embedded, the arrays are formed sequentially and then bonded to opposing sides of the optical spacer. The component layers (i.e., icon layer, spacer layer, etc.) are as described herein.

[0073] In certain embodiments of the present disclosure, a first icon layer and a second icon layer are bonded together to create at least one OVE, such as a rolling bar, a composite color, or a color shift. The icon elements are high-resolution icon elements with widths of 0.6 μm to about 5.5 μm, or spaced less than about 7.7 μm apart.

[0074] According to some embodiments, a method of authenticating a valuable item is provided, and in certain embodiments according to the present disclosure, the method includes coupling an OVSD to the valuable item. Authenticating the valuable item includes examining the OVSD to identify a predetermined OVE.

[0075] In another aspect of the present disclosure, a valuable item is provided, and in certain embodiments according to the present disclosure, the valuable item includes a substrate interface and an OVSD, the OVSD being coupled to the substrate interface.

[0076] In another aspect, a banknote is provided that includes: (i) a substrate layer having a first side and an opposing second side; (ii) a first icon layer having a first array of icon elements; and (iii) a second icon layer having a second array of icon elements, wherein the icon elements are high-resolution icon elements. The first icon layer and the second icon layer are combined to form a composite structure, such that at least one optically variable effect is observable when the composite structure is viewed from at least one side of the composite structure. Preferably, the OVE is selected from a rolling bar, a composite color, or a color shift. In certain embodiments according to the present disclosure, the OVE is observable from both sides of the composite structure. In certain embodiments according to the present disclosure, the substrate layer is at least one of a polymeric material or a cellulosic material.

[0077] In certain embodiments according to the present disclosure, a substrate layer is disposed between the first and second icon layers. Alternatively, an optical spacer is disposed between the first and second icon layers to form a composite structure that is then bonded to at least one of the first or second sides of the substrate layer. In certain embodiments according to the present disclosure, the composite structure is in the form of a surface-applied, windowed, or embedded patch or thread.

[0078] The OVSDs described herein are further illustrated by reference to specific embodiments that are illustrated in the accompanying drawings.

[0079] FIG. 1 shows a cross section of an OVSD resulting in an OVE without an icon element filled or coated therein, according to various embodiments of the present disclosure.

[0080] Referring to the non-limiting example of FIG. 1 , an OVSD 10 is shown. According to certain embodiments, the OVSD 10 includes an optical spacer 12 disposed between a first icon layer 11 and a second icon layer 13. The first icon layer 11 includes an array of unfilled or uncoated icon elements 11 a. In the non-limiting example of FIG. 1 , the icon elements 11 a are provided as recessed lines, while the second icon layer 13 includes an array of unfilled / uncoated icon elements 13 a in the form of recessed dots. According to various embodiments, the icon elements 11 a and 13 a exhibit high resolution, and the first icon layer 11 and the second icon layer 13 are bonded together and misaligned to create the OVE.

[0081] While in the non-limiting example of FIG. 1 the icon elements 11a of the first icon layer 11 comprise recessed lines and the icon elements 13a of the second icon layer 13 comprise recessed dots, it is also conceivable that the dots and lines can be reversed or that both icon layers 11, 13 comprise dots or lines, in particular such that the dots of individual sections of the first icon layer 11 overlap with the dots of the second icon layer 13, or the dots of the first icon layer 11 overlap with the lines of the second icon layer 13, or the lines of the second icon layer 13 overlap with the dots of the first icon layer 11.

[0082] In an example of an OVSD manufactured according to the embodiment of FIG. 1, high-resolution icon elements 11a, 13a create an OVSD that generates an OVE without the use of a lens array, thereby enabling such an OVSD to be used as an anti-counterfeiting tool. According to certain embodiments, a lensless structure such as that shown in FIG. 1 simplifies the manufacturing process and enables the formation of an OVE while avoiding the challenges of aligning icon elements with the lens structure. Additionally, operational advantages of a lensless OVSD such as that shown in FIG. 1 include avoiding problems associated with contamination and damage to micro-optical lenses.

[0083] FIG. 2 shows a cross section of an OVSD resulting in an OVE coated with icon elements of first and second icon layers according to some embodiments of the present disclosure.

[0084] Referring to the non-limiting example of FIG. 2, an example of an OVSD 10 is shown. According to certain embodiments, an optical spacer 12 is disposed between a first icon layer 11 and a second icon layer 13. The first icon layer and the second icon layer 13 are indirectly coupled and offset in certain embodiments so that the OVSD projects the OVSD. In the exemplary example of FIG. 2, the icon elements 13a, 11a are high resolution and have a coating 14a on the first icon layer 11 and coated on the second icon layer 13. The coating 14a on the icon elements 11a, 13a can be coated in a desired pattern, such as by coating the base of the icon element 11a as in the first icon layer 11, or by coating 14a portions on the base of the icon element 13a on the second icon layer 13, or by coating 14a protrusions as in the second icon layer 13.

[0085] FIG. 3 shows a cross section of an OVSD resulting in an OVE filled with icon elements of a second icon layer according to certain embodiments of the present disclosure.

[0086] Referring to the non-limiting example of FIG. 3, an example of an OVSD 10 is shown. According to various embodiments, an optical spacer 12 is disposed between a first icon layer 11 and a second icon layer 13. Each icon layer 11, 13 includes a portion having high-resolution icon elements 13a. In various embodiments, the icon elements 11a of the first icon layer 11 and the icon elements 13a of the second icon layer 13 are arranged in an array such that they are rotationally offset. According to the exemplary embodiment of FIG. 3, the icon elements 13a of the second icon layer 13 are filled with a contrast material filler 14b. When viewed from the side closest to the first icon layer 11, an OVE in the form of a rolling bar is visible.

[0087] FIG. 4 shows a cross section of an OVSD resulting in an OVE in which the icon elements of the first icon layer are filled and the icon elements of the second icon layer are coated, according to some embodiments of the present disclosure.

[0088] Referring to the illustrative example of FIG. 4, one example of an OVSD according to various embodiments of the present disclosure is shown. According to various embodiments, an optical spacer 12 is disposed between a first icon layer 11 and a second icon layer 13. As shown in this illustrative example, the icon elements 11a of the first icon layer 11 are filled with a contrast material filler 14b, while the icon elements of the second icon layer 13 are coated with a contrast material coating 14a in a pattern that extends along the base and side portions of the recesses 13a. The first icon layer 11 and the second icon layer 13 are formed simultaneously on opposite sides of the optical spacer 12 and are offset to create the OVE.

[0089] FIG. 5 shows a cross section of an OVSD resulting in an OVE without separate optical spacers and without filled or coated icon elements, according to various embodiments of the present disclosure.

[0090] Referring to the non-limiting example of Figure 5, one example of an OVSD 20 is shown. According to some embodiments, a first icon layer 21 is directly bonded to a second icon layer 23. In this illustrative example, there is no optical spacer disposed between the first icon layer 21 and the second icon layer 23. The first icon layer 21 and the second icon layer 23 have arrays of icon elements 21a and 23a, respectively. The icon elements 21a of the icon layer 21 and the icon elements 23a of the icon layer 23 are high-resolution icon elements that can be offset to create an OVE even if the icon elements 21a, 23a are not filled or coated.

[0091] FIG. 6 illustrates a cross section of an OVSD resulting in an OVE with embedded icon elements of first and second icon layers according to certain embodiments of the present disclosure.

[0092] Referring to the non-limiting example of FIG. 6 , an example of an OVSD 30 according to various embodiments of the present disclosure is shown. According to some embodiments, an optical spacer 32 is disposed between a first icon layer 31 and a second icon layer 33. The first icon layer 31 and the second icon layer 33 are formed and then transferred to be bonded to opposite sides of the optical spacer 32. According to various embodiments, the high-resolution recesses in the first icon layer 31 and the second icon layer 33 are recessed such that their bases are positioned away from the optical spacer and their tops are positioned toward the optical spacer 32. The arrays of icon elements in the icon layers 31 and 33 are offset and include high-resolution icon elements 31 a and 33 a, respectively. As shown in the non-limiting example of FIG. 6 , a contrast material is disposed within the recesses as a coating 34 a.

[0093] FIG. 7 shows a cross section of an OVSD resulting in an OVE in which the icon elements of the first icon layer are coated or filled posts and the icon elements of the second icon layer are filled voids, according to various embodiments of the present disclosure.

[0094] Referring to the non-limiting example of Figure 7, an OVSD 40 according to various embodiments of the present disclosure is shown. According to a particular embodiment of the OVSD 40, an optical spacer 42 is disposed between a first icon layer 41 and a second icon layer 43. As shown in this illustrative example, the first icon layer 41 includes high-resolution posts coated with a coating 44a and filled (e.g., by printing) with filler 44b. The second icon layer 43 includes high-resolution depressions filled with filler 44b. The first icon layer 41 and the second icon layer 43 are misaligned to produce a composite color that changes as the viewpoint of the OVSD changes.

[0095] FIG. 8 shows a cross section of an OVSD resulting in an OVE in which the icon elements of the first icon layer are coated or filled posts and the icon elements of the second icon layer are coated posts, according to certain embodiments of the present disclosure.

[0096] Referring to the non-limiting example of FIG. 8 , an OVSD 50 is shown. According to certain embodiments, in the OVSD 50, an optical spacer 52 is disposed between a first icon layer 51 and a second icon layer 53. Both the first icon layer 51 and the second icon layer 53 include posts within their respective arrays of high-resolution icon elements. The posts of the first icon layer include filler (e.g., a material deposited through a printing process) 54b and a coating 54a, while the posts of the second icon layer 53 include a patterned coating 54a extending along the side and top portions of the posts. The first icon layer 51 and the second icon layer 53 are misaligned to create an OVE that is observable from both sides of the OVSD.

[0097] FIG. 9 shows a cross section of an OVSD resulting in an OVE including icon elements of a first icon layer that are coated and icon elements of a second icon layer that are filled posts, according to some embodiments of the present disclosure.

[0098] Referring to the non-limiting example of FIG. 9 , an OVSD 50 is shown. According to various embodiments, in the OVSD 50, an optical spacer 52 is disposed between a first icon layer 51 and a second icon layer 53. In this illustrative example, both the first icon layer 51 and the second icon layer 53 include posts within their respective arrays of high-resolution icon elements. The posts of the first icon layer 51 include filler 54b covering the sides and top of the posts, while the posts of the second icon layer 53 include printed coatings 54a in certain embodiments. The optical spacer 52 can be adjusted as needed to increase the speed of the OVE. The positions of the first icon layer and the second icon layer are misaligned to generate the OVE.

[0099] FIG. 10 shows an isometric cross-sectional view of an OVSD including first and second icon layers including coated icon elements, resulting in an OVE in the form of a rolling bar, according to certain embodiments of the present disclosure.

[0100] Referring to the non-limiting example of FIG. 10 , an isometric view of an OVSD 60 is shown. According to certain embodiments, in the OVSD 60, an optical spacer 62 is disposed between a first icon layer 61 and a second icon layer 63. In various embodiments, the optical spacer 62 has a thickness of approximately 30 μm. As shown in this illustrative example, the arrays of high-resolution icon elements in the first icon layer 61 and the second icon layer 63 are coated with a contrasting material (e.g., coating) 64b. The first icon layer 61 and the second icon layer 63, in various embodiments, are offset to create an OVE. In the non-limiting example of FIG. 10 , the OVE includes a set of rolling bars 65, 66 having at least one color different from the color of the contrasting material. As shown in this non-limiting example, the first set of rolling bars 65 includes a border 65a.

[0101] FIG. 11 shows an isometric cross-sectional view of an OVSD in a banknote with a "rolling bar" OVE, according to some embodiments of the present disclosure.

[0102] 11, a valuable item 70 is shown including an OVSD 60. In this illustrative example, the valuable item 70 includes a banknote. According to various embodiments, the OVSD 60 that provides the OVE has features including a first set of rolling bars 65 and a second set of rolling bars 66. According to various embodiments, the first set of rolling bars 65 further includes one or more visible boundaries 65a.

[0103] FIG. 12 shows a cross section of an OVSD according to various embodiments of the present disclosure, where a first icon layer includes filled posts and a second icon layer is partially filled with a second transparent material such that the areas between the posts are only partially filled.

[0104] Referring to the non-limiting example of FIG. 12 , an OVSD 80 is shown. According to various embodiments, the OVSD 80 includes a first icon layer 81 (e.g., first icon layer 11 of FIG. 1 ), an optical spacer layer 82 (e.g., optical spacer layer 12 of FIG. 1 ), and a second icon layer 83 (e.g., icon layer 13 of FIG. 1 ). As shown in the non-limiting example of FIG. 12 , one or more image icons in the second icon layer 83 are filled with a contrast material 84 (e.g., contrast material 14b of FIG. 3 ). Additionally, in some embodiments, the image icons in the first icon layer 81 are partially filled with a transparent material 85, which, in certain embodiments, contributes to the improved sharpness and contrast of the OVE provided by the OVSD 80.

[0105] An example of an OVSD according to certain embodiments of the present disclosure includes an OVSD including a first icon layer including a first array of icon elements and a second icon layer coupled to the first icon layer including a second array of icon elements, wherein the icon elements of the first icon layer and the second icon layer are lines, dots, or a combination thereof, and one or more of the icon elements of the first icon layer or the second icon layer exhibit high resolution.

[0106] Examples of OVSDs according to certain embodiments of the present disclosure include OVSDs in which at least one of the first icon layer and the second icon layer is an interference layer.

[0107] Examples of OVSDs according to certain embodiments of the present disclosure include an OVSD in which a first icon layer and a second icon layer are coupled to one another, such that at least one OVE is provided by the OVSD when an icon element in one of the first or second icon layers is viewed from at least one side of the OVSD adjacent to the other icon layer.

[0108] Examples of OVSDs according to certain embodiments of the present disclosure include OVSDs in which the OVE comprises a rolling bar.

[0109] Examples of OVSDs according to certain embodiments of the present disclosure include OVSDs in which the rolling bar is multicolored.

[0110] Examples of OVSDs according to certain embodiments of the present disclosure include OVSDs in which the OVE comprises composite colors.

[0111] Examples of OVSDs according to certain embodiments of the present disclosure include an OVSD where the OVE is viewable from a first viewpoint, with a first icon layer facing the viewer, and from a second viewpoint, with a second icon layer facing the viewer.

[0112] Examples of OVSDs according to certain embodiments of the present disclosure include OVSDs that further comprise a transparent material partially filling the area between the posts of at least one of the first icon layer or the second icon layer.

[0113] Examples of OVSDs according to certain embodiments of the present disclosure include OVSDs in which at least one icon element of the first array of icon elements and the second array of icon elements has one or more width dimensions in the range of 0.5 μm to 6.5 μm, or spacing dimensions between icon elements that are less than 7.7 μm.

[0114] Examples of OVSDs according to certain embodiments of the present disclosure include OVSDs in which icon elements of both the first array of icon elements and the second array of icon elements comprise one or more voids or posts.

[0115] Examples of OVSDs according to certain embodiments of the present disclosure include OVSDs in which the voids comprise one or more depressions or holes.

[0116] Examples of OVSDs according to certain embodiments of the present disclosure include OVSDs in which the posts comprise one or more of a plateau, a protrusion, or a mesa.

[0117] Examples of OVSDs according to certain embodiments of the present disclosure include OVSDs with high resolution having line widths between 0.5 μm and 5.0 μm.

[0118] Examples of OVSDs according to certain embodiments of the present disclosure include OVSDs with high resolution line spacing between 0.5 μm and 5.0 μm.

[0119] Examples of OVSDs according to certain embodiments of the present disclosure include OVSDs with high resolution having dot widths between 0.5 μm and 6.5 μm.

[0120] Examples of OVSDs according to certain embodiments of the present disclosure include OVSDs in which one or more of the first array of icon elements or the second array of icon elements have a pitch between 1.0 μm and 6.5 μm.

[0121] Examples of OVSDs according to certain embodiments of the present disclosure include OVSDs with high resolution having dot spacing between 0.5 μm and 5.0 μm.

[0122] Examples of OVSDs according to certain embodiments of the present disclosure include OVSDs that further comprise an optical spacer between the first icon layer and the second icon layer.

[0123] An example of an OVSD according to certain embodiments of the present disclosure includes an OVSD in which a first array of icon elements and a second array of icon elements are arranged to create an offset between the first array of icon elements and the second array of icon elements.

[0124] Examples of OVSDs according to certain embodiments of the present disclosure include OVSDs in which the misalignment includes one or more of dimensional, rotational, periodic, or zonal misalignment.

[0125] Examples of OVSDs according to certain embodiments of the present disclosure include OVSDs in which OVEs are generated as the observer's viewpoint changes relative to the OVSD.

[0126] Examples of OVSDs according to certain embodiments of the present disclosure include OVSDs in which the icon elements of at least one of the first icon layer and the second icon layer are filled or coated with a contrasting material.

[0127] Examples of OVSDs according to certain embodiments of the present disclosure include OVSDs in which icon elements of at least one of the first icon layer and the second icon layer include posts that include a contrasting material.

[0128] An example of an OVSD according to certain embodiments of the present disclosure includes an OVSD in which icon elements of a first icon layer and icon elements of a second icon layer are formed by an icon tool.

[0129] Examples of OVSDs according to certain embodiments of the present disclosure include OVSDs in which a first icon layer and a second icon layer are integrated as opposing sides of an optical spacer.

[0130] An example of a particular embodiment of the present disclosure includes the use of an OVSD according to the present disclosure to authenticate a valuable item.

[0131] An example method of manufacturing an OVSD according to certain embodiments of the present disclosure includes providing an optical spacer layer, applying a first icon layer to a first side of the optical spacer layer and a second icon layer to a second side of the optical spacer layer, and forming an array of icon elements on or in the first icon layer and a second array of icon elements on or in the second icon layer, the icon elements being high resolution icon elements, the second side being opposite the first side of the optical spacer layer.

[0132] An example of a method for generating an OVSD according to certain embodiments of the present disclosure includes a method in which a first icon layer and a second icon layer generate an optically variable effect.

[0133] Examples of methods for generating OVSDs according to certain embodiments of the present disclosure include methods in which the optically variable effect includes one or more of a rolling bar, a composite color, or a color shift.

[0134] Examples of methods for generating OVSDs according to certain embodiments of the present disclosure include methods in which high resolution icon elements have a width range of about 0.5 μm to about 6.5 μm or spacing of less than about 7.7 μm.

[0135] Examples of banknotes according to certain embodiments of the present disclosure include banknotes comprising a substrate layer having a first side and a second opposing side, a first icon layer having an array of first icon elements, and a second icon layer having an array of second icon elements, wherein the icon elements of the first icon layer and the second icon layer are high resolution icon elements, and wherein the first icon layer and the second icon layer provide an optically variable effect (OVE).

[0136] Examples of banknotes according to certain embodiments of the present disclosure include banknotes in which a first icon layer and a second icon layer are combined to form a composite structure, wherein the composite structure has at least one optically variable effect observable when viewed from at least one side of the composite structure.

[0137] Examples of banknotes according to certain embodiments of the present disclosure include banknotes in which the optically variable effect includes one or more of a set of rolling bars, a composite color, or a color shift.

[0138] Examples of banknotes according to certain embodiments of the present disclosure include banknotes in which the optically variable effect is observable from both sides.

[0139] Examples of banknotes according to certain embodiments of the present disclosure include banknotes in which the substrate layer is at least one of a polymeric material or a cellulosic material.

[0140] Examples of banknotes according to certain embodiments of the present disclosure include banknotes in which a substrate layer is disposed between a first icon layer and a second icon layer.

[0141] Examples of banknotes according to certain embodiments of the present disclosure include banknotes in which an optical spacer is disposed between a first icon layer and a second icon layer to form a composite structure bonded to at least one of a first side or a second side of a substrate layer.

[0142] Examples of banknotes according to certain embodiments of the present disclosure include banknotes that further comprise surface-applied, windowed, or embedded patches or threads.

[0143] Although the present disclosure has been described in various embodiments, various changes and modifications may be suggested to one skilled in the art. The present disclosure is intended to cover such changes and modifications as fall within the scope of the appended claims.

[0144] Nothing in this disclosure should be interpreted as implying that any particular element, step, or function is an essential element, step, or function required to be included in the claims. The scope of the subject matter of this patent is defined solely by the claims. Moreover, no claim is intended to invoke 35 U.S.C. § 112(f) unless the precise word "means" is followed by a participle.

Claims

1. a first icon layer (11) including a first array of icon elements (11a); a second icon layer (13) coupled to the first icon layer and including a second array of icon elements (13a); Including, further comprising a transparent material (85) partially filling an area between posts on at least one of the first icon layer or the second icon layer; the icon elements of the first icon layer and the second icon layer are lines, dots, or a combination thereof; one or more icon elements of the first icon layer or the second icon layer exhibit high resolution; At least one icon element of the first array of icon elements and the second array of icon elements comprises: a width dimension in the range of 0.5 μm to 6.5 μm, or Spacing between icon elements less than 7.7 μm having one or more of: Optically Variable Security Device (OVSD) (10).

2. The OVSD of claim 1 , wherein at least one of the first icon layer and the second icon layer is an interference layer.

3. 10. The OVSD of claim 1, wherein the first icon layer and the second icon layer are coupled together such that at least one optically variable effect (OVE) is produced by the OVSD when an icon element in one of the first or second icon layers is viewed from at least one side of the OVSD adjacent the other icon layer.

4. The OVSD of claim 3 , wherein the OVE comprises a rolling bar (65).

5. 5. The OVSD of claim 4, wherein the rolling bar is multicolored.

6. The OVSD of claim 3 , wherein the OVE includes a color switch.

7. The OVSD of claim 3 , wherein the OVE comprises a composite color.

8. 4. The OVSD of claim 3, wherein the OVE is viewable from a first viewpoint in which the first icon layer faces a viewer and from a second viewpoint in which the second icon layer faces the viewer.

9. 10. The OVSD of claim 1, wherein icon elements of both the first array of icon elements (51) and the second array of icon elements (53) include one or more voids or posts.

10. The OVSD of claim 9 , wherein the voids comprise one or more depressions or holes.

11. The OVSD of claim 9 , wherein the post comprises one or more plateaus, protrusions, or mesas.

12. The OVSD of claim 1 , wherein the high resolution comprises a line width between 0.5 μm and 5.0 μm.

13. The OVSD of claim 1 , wherein the high resolution comprises a line spacing between 0.5 μm and 5.0 μm.

14. The OVSD of claim 1 , wherein the high resolution comprises a dot width between 0.5 μm and 6.5 μm.

15. 10. The OVSD of claim 1, wherein one or more of the first array of icon elements or the second array of icon elements has a pitch between 1.0 μm and 6.5 μm.

16. The OVSD of claim 1 , wherein the high resolution comprises a dot spacing between 0.5 μm and 5.0 μm.

17. The OVSD of claim 1 , further comprising an optical spacer between the first icon layer and the second icon layer.

18. 10. The OVSD of claim 1, wherein the first array of icon elements and the second array of icon elements are arranged to create an offset between the first array of icon elements and the second array of icon elements.

19. 20. The OVSD of claim 18, wherein the misalignment comprises one or more of dimensional, rotational, periodic, or zonal misalignment.

20. 10. The OVSD of claim 1, wherein an optically variable effect (OVE) occurs as an observer's viewpoint changes relative to the OVSD.

21. At least one icon element of the first icon layer and the second icon layer is 10. The OVSD of claim 1, which is filled or coated with a contrast material.

22. 10. The OVSD of claim 1, wherein at least one icon element of the first icon layer and the second icon layer includes a post comprising a contrasting material.

23. The OVSD of claim 1 , wherein the icon elements in the first icon layer and the icon elements in the second icon layer are formed by an icon tool.

24. 10. The OVSD of claim 1, wherein the first icon layer and the second icon layer are integrated as opposing sides of an optical spacer.

25. providing an optical spacer layer (12); applying a first icon layer (11) to a first side of the optical spacer layer and a second icon layer (13) to a second side of the optical spacer layer; partially filling areas between posts in at least one of the first icon layer or the second icon layer with a transparent material (85); forming a first array of icon elements (11a) on or in said first icon layer and a second array of icon elements (13a) on or in said second icon layer; Including, the icon element is a high-resolution icon element; the second side facing the first side of the optical spacer layer; At least one icon element of the first array of icon elements and the second array of icon elements comprises: a width dimension in the range of 0.5 μm to 6.5 μm, or Spacing between icon elements less than 7.7 μm having one or more of: A method for manufacturing an optically variable security device (OVSD).

26. 26. The method of claim 25, wherein the first icon layer and the second icon layer produce an optically variable effect.

27. 27. The method of claim 26, wherein the optically variable effect comprises one or more of a rolling bar, a composite color, or a color shift.

28. 26. The method of claim 25, wherein the high resolution icon elements have widths ranging from 0.5 μm to 6.5 μm, or spacings less than 7.7 μm.

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