RU2780764C2 - Lens-free micro-optical film - Google Patents

Abstract

FIELD: information protection.

SUBSTANCE: invention relates to optically variable protective devices containing protective threads, inserts, labels, strips. Protective devices use a lens-free structure, in which a set of symbol layers are connected for provision of an artificially created image or an artificial color, which has an optically variable effect. Each symbol layer contains a symbol array with high resolution, which are aligned relatively to each other and located at a distance from each other to provide a desired optically variable effect.

EFFECT: invention provides for confirmation of authenticity of protected documents.

42 cl, 12 dwg

Description

FIELD OF TECHNOLOGY

[1] The present invention relates generally to embodiments of a security device suitable for use in authenticating (i.e., aesthetically and/or protecting) a valuable item that could otherwise be counterfeited, fabricated, falsified, copied. and/or issued to consumers as genuine. More specifically, some embodiments of the present invention relate to what is referred to herein as an optically variable security device (OVSD). Certain embodiments of the OVSD of the present invention are multi-layered and provide an optically variable effect (OVE) when the OVSD is viewed from different viewpoints. The OVE is preferably a dynamic effect in which a change in the viewpoint results in a change in the location, size, shape, or color of the image projected by the OVSD. OVSDs according to various embodiments of the present invention are particularly suitable for authenticating valuable items such as security documents (eg, money documents, identification documents) and high value consumer goods.

BACKGROUND OF THE INVENTION

[2] Suppliers of genuine high value items (products) often struggle with counterfeiters who attempt to use less expensive processes to make imitations of genuine products and pass these counterfeits as genuine versions to unsuspecting consumers. For example, counterfeiters often create counterfeit security documents by using sophisticated printing and copying techniques to create photocopies of genuine security documents and pass off forgeries as genuine documents. Some consumer products do not use security labels to verify authenticity, in which case counterfeiters simply duplicate the consumer product and pass it off as genuine. However, some consumer products use security labels to verify the authenticity of consumer products; in this case, the counterfeiters have to make a duplicate of the consumer product with a security label.

[3] To thwart counterfeiting efforts, some manufacturers of genuine valuables use security devices that display optically variable images. These elements have become useful tools in the fight against counterfeits and counterfeit goods, since even the most sophisticated copying and printing technology is unable to reproduce the optical variability created by these security devices.

[4] The following are several types of optical protective devices. For example, US Pat. Nos. US7,333,268, US7738175 and US7468842 issued to Steenblik et al. describe one or more optical security devices that provide artificially generated images when an array of image elements is viewed through an array of focusing elements. These artificially created images may exhibit optical variability as they present a range of different optical effects (eg changing location, color, size, shape, quantity, etc.) when viewed from different viewpoints. Material constructs capable of producing such effects are also described in US Pat. US7738175 to Steenblik et al., US Patent No. US7830627 to Commander et al. , US Pat. No. US8149511 to Kaule et al.; US Pat. No. US8878844 to Kaule et al.; US Pat. No. US8786521 to Kaule et al.; European Patent Application No. EP2162294 to Kaule et al.; and European Patent Application No. EP2164713 issued to Kaule.

[5] While there are several optical security devices that are suitable for providing enhanced security and authentication for a variety of highly secure or high value products, there remains room for improvement in the performance and functionality of optical security devices. For example, devices such as those described in the referenced documents above may often require multiple manufacturing processes to create the image layer and the focusing layer separately. This can be costly and can cause variability in the manufacturing process. Moreover, the optical security devices described above may require precise alignment between the array of focusing elements and the array of characters after fabrication, which complicates the process. Optical security devices are often lens-based systems containing an array of lenses as focusing elements in a focusing layer. The lenses may become dirty, which may distort or obscure the artificial image provided by the protective device.

[6] One alternative to lens-based protective devices is disclosed in Australian Patent Application No. AU2017101291 ("'291 Application"). It discloses a device having at least two layers, the first layer having a first pattern and the second layer having a second pattern. The second layer is separated from the first layer by a distance, and the second pattern contains at least one isolated area, which is a scaled version of the corresponding area of the first pattern. The device is supposed to create a three-dimensional visual effect when viewing the device due to moiré interference. This moiré interference effect occurs as a result of global scaling, in which the size of lines or dots and the distance between them increases or decreases in one layer relative to another.

[7] The device described in the '291 application has its own disadvantages. In particular, the lines or dots are low resolution lines that are printed or embossed using conventional printing machines such as the Simultan printing press. The absence of high-resolution lines or dots limits the resolution of any image projected by the device. This is important in cases where the thickness of the device is a critical part of the authentication of a valuable item, such as when the device is to be used in the authentication of security documents (eg, banknotes).

SUMMARY OF THE INVENTION

[8] Certain embodiments according to the present invention provide one or more of the following: (i) a security device, (ii) a method for manufacturing a security device, (iii) an application of a security device or a method for using a security device, (iv) a valuable article containing a security a device, or (v) a product characterized by a method of obtaining it, containing a protective device made using the method described herein.

[9] According to one aspect, a security device is provided, wherein in some embodiments, the security device is an Optically Variable Security Device (OVSD) comprising (i) a first character layer having a first character array; (ii) a second symbol layer connected to the first symbol layer and having a second symbol array; wherein the symbols of the first symbol layer and the second symbol layer are lines, dots, or a combination thereof; the symbols are high-resolution symbols.

[10] According to another aspect, a method for producing an OVSD is provided, wherein in some embodiments, the method includes: (i) providing an optical spacer layer; (ii) forming a first character layer on a first side of the optical spacer layer and forming a second character layer on a second, opposite side of the optical spacer; (iii) generating a character array on or in the first character layer and generating a second character array on or in the second character layer; the symbols are high-resolution symbols.

[11] According to another aspect, a method for authenticating a valuable item is provided, wherein in some embodiments, the method includes attaching an OVSD described herein to a valuable item. Other technical features may be apparent to a person skilled in the art from the following figures, descriptions and claims.

[12] According to another aspect, a valuable article is provided, wherein in various embodiments, the valuable article comprises: (i) an OVSD as described herein; and (ii) a contact surface of the substrate, wherein the OVSD is connected to the contact surface of the substrate. In some embodiments according to the present invention, the article of value is a banknote comprising: (i) a substrate layer having a first side and a second opposite side; (ii) a first character layer having a first character array; (iii) a second character layer having a second character array; the symbols are high-resolution symbols.

[13] According to another aspect, the embodiments of the present invention provide a product and a method for producing the same, wherein the product is a valuable item according to various embodiments of the present invention, which is obtained using a method according to some embodiments of the present invention.

[14] According to various embodiments of the present invention, an OVSD comprises: an OVSD according to one or more embodiments of the present invention and a substrate contact surface, wherein the OVSD is connected to the valuable article via the substrate contact surface. In some embodiments, the item of value is a banknote comprising (i) a backing layer having a first side and a second opposite side; (ii) a first character layer having a first character array partially filled with a transparent material; (iii) a second character layer having a second character array; the symbols are high-resolution symbols that are in the form of filled columns.

[15] Embodiments according to the present invention will be described in detail below so that a person skilled in the art (hereinafter referred to as "specialist") can make and use it without resorting to excessive experimentation. Thus, the embodiments described above or below in this disclosure are not intended to limit the scope of the embodiments as set forth in the description and claims of the present invention, and should be interpreted solely as illustrative embodiments presented to describe some embodiments. It should be apparent to those skilled in the art that many more modifications and embodiments are possible beyond those expressly described herein without departing from the inventive concepts presented herein. In particular, the terms "comprises", "having" and "comprising" should be interpreted as referring to elements, components or steps without exception, which means that said elements, components or steps may be present or used or exist in combination with other elements, components or steps that are not explicitly mentioned or may exist in combination, in particular with other embodiments described herein.

[16] In interpreting the terms used in the present invention, it should be noted that in the context of this document and in the appended claims, the singular forms include the plural forms, unless the context clearly dictates otherwise.

[17] 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 mentioned. The publications described in this document are for their disclosure only.

[18] Before proceeding to the detailed description below, it may be useful to define certain words and phrases used in this patent document. The term "connect" and its derivatives refer to any direct or indirect connection between two or more elements, whether these elements are in physical contact with each other or not. The terms "comprise" and "comprise", as well as their derivatives, mean the inclusion of, among other things. The term "or" is inclusive, meaning "and/or". The phrase "associated with", as well as its derivatives, means "to include", "to be included in", "to reciprocally connect with", "to contain", "to be contained within", "to connect with", "to be associated with", "to communicate with", "interact with", "alternate", "join", "be in close proximity to", "be associated with", "have", "have a property", "be associated with", or the like. Phrase "at least one of" when used with a list of elements means that various combinations of one or more of the listed elements may be used, and only one element from the list may be required. 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.

[19] Other specific words and phrases are defined in this patent document. Those skilled in the art will appreciate that in many, if not most, cases, such definitions apply to both past and future use of such defined words and phrases.

BRIEF DESCRIPTION OF GRAPHICS

[20] For a better understanding of the present invention and its advantages, reference is made to the following description taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts.

[21] FIG. 1 is a cross-sectional view of an OVSD that provides an OVE, with no symbols filled or covered, in accordance with various embodiments of the present invention.

[22] FIG. 2 is a cross-sectional view of an OVSD that provides an OVE with the symbols of the first and second symbol layers covered, in accordance with some embodiments of the present invention.

[23] FIG. 3 is a cross-sectional view of an OVSD that provides an OVE with the symbols of the second symbol layer filled, in accordance with some embodiments of the present invention.

[24] FIG. 4 is a cross-sectional view of an OVSD that provides OVE with the symbols of the first symbol layer filled and the symbols of the second symbol layer covered, in accordance with some embodiments of the present invention.

[25] FIG. 5 is a cross-sectional view of an OVSD that provides OVE without a separate optical spacer and without filled or covered symbols, in accordance with various embodiments of the present invention.

[26] FIG. 6 is a cross-sectional view of an OVSD that provides an OVE with the symbols of the first and second symbol layers recessed, in accordance with some embodiments of the present invention.

[27] FIG. 7 is a cross-sectional view of the OVSD that OVE provides, with the symbols of the first symbol layer being columns that are covered or filled, and the symbols of the second symbol layer being filled voids, in accordance with various embodiments of the present invention.

[28] FIG. 8 is a cross-sectional view of the OVSD that OVE provides, with the symbols of the first symbol layer being columns that are covered or filled, and the symbols of the second symbol layer being columns that are covered, in accordance with some embodiments of the present invention.

[29] FIG. 9 is a cross-sectional view of the OVSD that OVE provides, with the symbols of the first symbol layer being covered and the symbols of the second symbol layer being filled columns, in accordance with some embodiments of the present invention.

[30] FIG. 10 is a sectional isometric view of an OVSD that includes first and second symbol layers with covered symbols and that provides rolling bar OVE, in accordance with some embodiments of the present invention.

[31] FIG. 11 is a sectional isometric view of an OVSD in a banknote with OVE rolling bands, in accordance with some embodiments of the present invention.

[32] FIG. 12 shows a cross-sectional view of an OVSD according to various embodiments of the present invention, wherein the first symbol layer comprises filled columns and the second symbol layer is partially filled with a second, transparent material such that the areas between the columns are only partially filled.

Definitions

[33] The terms "coating" or "coating" as used herein with respect to a contrast material encompasses applying the contrast material to a void such that the contrast material in the void occupies less than 50% of the depth of the void. In some embodiments, the "plating" or "coating" follows the shape of the cavity boundaries, including the base and optionally the side walls. As used herein as a transitive verb, "coat" or "cover" covers the coating of a column or solid area between voids.

[34] The term "contrast material" as used herein encompasses material that, when included as part of character layers, creates a visible difference between characters and surrounding/adjacent materials.

[35] The term "size mismatch" as used herein encompasses differences in one or more of size, shape, or localized angle between the characters of the first character array and the characters of the second character array.

[36] The terms "filling" or "filling" as used herein with respect to a contrast material encompass the application of a contrast material to a void such that the contrast material in the void occupies 50% or more of the depth of the void; or to printing columns with a contrasting material.

[37] The term "high resolution" as used herein in relation to a character or set of characters encompasses at least one of (i) lines and/or dots having a width in the range of 0.5 µm to about 6.5 µm , or (ii) lines and/or dots spaced less than 7.7 µm.

[38] The terms "hole" or "through hole" as used herein in relation to a void encompass an OVSD structure or region extending from one side of an OVSD layer to the other side of at least that layer (e.g., a first character layer, a second character layer or optical spacer).

[39] The term "rise" as used herein in relation to columns encompasses columns whose height (ie, extension from the base) is greater than the width.

[40] The term "optically variable effect" or "OVE" as used herein encompasses the display or projection of an image or set of images, such as an artificially generated image that changes at least one of location, size, shape, or color when the optically variable security device is viewed from different viewpoints.

[41] The term "periodic mismatch" as used herein encompasses the difference in period of a character array present in one of the first character array and the second character array relative to the other of them.

[42] The term "flat components" as used herein in relation to columns encompasses a column whose base width is greater than its height (ie, its extent from the first character layer or from the second character layer).

[43] The term "protrusion" as used herein in relation to columns encompasses a column having sides that are not parallel to each other, or having vertices that are not parallel to their bases.

[44] The term "recess" as used herein in relation to the void, covers the area of OVSD, having a depth that ends within the thickness of the layer in which it is made.

[45] The term "rotation mismatch" as used herein encompasses the difference in angular orientation of the repeating pattern of one of the first character array relative to the repeating pattern of the second character array.

[46] The term "spacing" in the context of this document covers the measured amount of the area (for example, a gap) between successive characters, for example, between two lines, two points, or between a line and a point, which form an array of characters or parts thereof.

[47] The term "artificial color" in the context of this document covers a color or set of colors projected by the OVSD, with the projected color coming from a character or set of characters that has a pigment with a color that is different from the color(s) projected or incoming from character(s) that have no pigment or color.

[48] The term "artificially generated image" as used herein encompasses an image or set of images projected by an OVSD, wherein the projected image is generated based on a character, character set, or portion of characters in a single character layer that is either (i) not observable by a human without visual assistance, such as with a magnifying tool or other superimposed character layer, or (ii) when the image provided by the character(s) in one character layer differs from the projected image, such as when portions of characters are combined to form a projected image.

[49] The term "voids" as used herein encompasses a recess or hole made in a layer of material (eg, first character layer, second character layer, or optical spacer layer) of an OVSD.

[50] The term "size-by-width" in the context of this document covers character-by-character width, such as line width or point width.

[51] The term "zonal mismatch" as used herein encompasses a difference in size match, rotation match, or periodic match in local areas of one of the first character array relative to the second character array.

DETAILED DESCRIPTION OF THE INVENTION

[52] Therefore, there remains a need for a security device that can be obtained using a lensless system to at least avoid some of the drawbacks mentioned above. Moreover, there remains a need for a security device that can be made with high resolution characters, making it more difficult for counterfeiters to copy as well as producing higher resolution images. In addition, there remains a need for a security device that can reduce the alignment restrictions required for conventional optical security devices. The inventors have unexpectedly found that this goal can be developed, at least in part, through some embodiments according to the present invention.

[53] According to various embodiments of the present invention, the OVSD comprises a first character layer having a first character array; a second character layer connected to the first character layer and having a second character array. The first symbol layer and the second symbol layer are positioned relative to each other such that an artificially generated image or artificial color is obtained when the OVSD is viewed through at least one of the first symbol layer and the second symbol layer.

[54] Various types of symbols are considered suitable for OVSD implementations. In some embodiments, the symbols include lines (elongated) or dots, or combinations thereof. Reference herein to lines or dots encompasses embodiments in which the lines or dots are intended to take on any shape or combination of shape. For example, lines can form triangles, rectangles, trapezoids, diamonds, rings, ovals, or combinations thereof, including complex shapes made up of sets of simpler shapes. Lines or dots can be arranged in preferred patterns or preferred characters (letters, numbers, designations, etc.). For example, in some embodiments, lines or dots are arranged in shapes in one of the first or second symbol layers such that, when viewed through the second symbol layer, rolling bands having an optically variable effect (OVE) are projected by the OVSD. Various exemplary OVEs will be described in more detail herein.

[55] High resolution symbols are used in OVSD according to various embodiments of the present invention. In some embodiments according to the present invention, the character resolution is higher than conventional printing technologies. In fact, in various embodiments, the resolution is such that characters printed at the resolution of these characters are not perceived by the naked eye. However, it has been surprisingly found that symbols in at least one of the first or second symbol layers can be generated at high resolution and still be perceived as OVE when viewed through another symbol layer. In some embodiments according to the present invention, all of the symbols are high resolution symbols. In some embodiments, only some of the symbols are high resolution symbols, such as in embodiments in which the high and low resolution symbols are arranged to provide particular pattern(s). In various embodiments, the symbols of both the first symbol layer and the second symbol layer are high resolution symbols. In one embodiment, the symbols in one of the first and second symbol layers are of high resolution. In some embodiments according to the present invention, the symbols of at least one of the first character array and the second character array have a width (line or dot) size in the range of about 0.5 µm to about 6.5 µm, or a character spacing size, which is less than 7.7 µm.

[56] In various embodiments according to the present invention, high resolution is provided by line widths ranging from about 0.5 µm to about 6.5 µm. In some embodiments, the line width is in the range of about 0.5 µm to about 5 µm.

[57] In various embodiments, high resolution is provided by a line spacing of less than 7.7 microns. In some embodiments, the line spacing is from about 0.5 µm to about 5.5 µm.

[58] In some embodiments, high resolution is provided by dot widths ranging from about 0.5 µm to about 6.5 µm. In some embodiments, the dot width is from 0.5 µm to about 5 µm.

[59] In at least one embodiment, high symbol resolution is provided by a line/dot pitch ranging from about 1.0 µm to about 6.5 µm. In some embodiments, the line/dot pitch ranges from about 1.0 µm to about 4.0 µm. In particular, the variability of the line/dot pitch in some embodiments is not limited to individual sections.

[60] In at least one embodiment, high resolution is achieved with a dot spacing of less than 7.7 microns. In various embodiments, the ranges are from about 0.5 µm to about 5.5 µm.

[61] This OVSD, in some embodiments, is a lensless system, and thus does not require microlenses or Fresnel lenses to generate an artificial image or artificial color. In particular, the OVSD according to various embodiments of the present invention does not require a lens system to obtain an artificial image or artificial color with OVE.

[62] The first symbol array and the second symbol array of the respective first and second symbol layers in some embodiments according to the present invention are positioned relative to each other such that they provide an artificially generated image having an Optically Variable Effect (OVE). For example, in some embodiments, the artificially generated image with OVE provided by OVSD contains rolling stripes. In at least one embodiment, the artificially generated OVE images comprise multicolor rolling stripes. In various embodiments, the OVE is a color change in which at least portions of the artificially generated image change color from one to another as the OVSD is tilted relative to a generally fixed viewpoint (eg, the viewer's eye). In some embodiments, the OVE provides an artificial color that is formed as a combination of the colors provided in the OVSD symbol layer. In some embodiments according to the present invention, the first and second symbol layers are connected in such a way that a variable artificially generated image is provided, containing rolling stripes, so that when the observer's point of view (POV) changes relative to OVSD, it seems that the rolling stripes move. The rolling strip OVE according to some embodiments of the present invention comprises at least two sets of strips that alternate with each other.

[63] In some embodiments according to the present invention, the OVSD provides OVE in the form of a color change, wherein the color of the artificially generated image or parts thereof changes from one color to another when viewed from OVSD from different angles. For example, in some embodiments according to the present invention, the first character array contains voids that are filled with or covered with a first color (eg, black pigment), and the second character array contains voids that are empty. When viewed from the side of the OVSD next to the second symbol array, the OVE can be seen as rolling bars, with this complete bar set containing a plurality of interleaved bar sets, with the first bar set having individual bars interleaved interleaved between the second set of rolling bars. The first set of rolling strips provides the first color and the second set of stripes provides the second color. When the device is tilted such that the viewpoint is changed, the color in each set changes. As one non-limiting example, in at least one embodiment, the first set of rolling strips provides a natural blue color and the second set of stripes provides a natural green color. When the OVSD is tilted, the natural blue color in the first set of rolling strips changes to the green color OVE, while the natural green color changes to the blue color OVE. Of course, it should be understood that in the context of the present application, it is not necessary that there be a change from the first color to the second color, a change from the second color to the first may occur, since various color changes can be simplified by changing the character pattern in at least one of the first layer. symbols and the second layer of symbols. Although the color change is described in relation to artificially generated images containing rolling stripes, it should be understood that the artificially generated image may have different patterns depending on the arrangement of characters, and thus the color change can also be applied to these different artificial image patterns. In at least one embodiment, the first set of rolling bands changes from blue to green. In some embodiments, the observed color shift provided as part of the OVE is due to interference generated by light transmitted through and reflected from the thin OVSD layers, whereby they act as a thin film optical filter. Different material thickness corresponds to different colors. As the OVSD material is tilted, the light path length also changes with respect to the viewer's eye, causing the wavelengths affected by the filter to change and hence the color to change. In another embodiment, the first set of rolling strips comprises a border strip having a border color. When changing the POV, the boundary color of the boundary bar, the first set of rolling bars and the second set of rolling bars are changed from the first color to the second color, respectively. In some embodiments according to the present invention, the OVSD projects artificial color, wherein the artificially generated image has a color that can be distinguished from the pigment used in filling, coating or printing characters. For example, in one particular embodiment, the symbols are filled or coated with yellow pigment, but the artificially created image is projected in yellow and/or green, thereby creating an artificial color. Other artificial colors or color combinations may also be created depending on the relative positioning of the first character layer and the second character layer, the spacing between layers, and the character size distribution/arrangement.

[64] In some embodiments according to the present invention, the OVSD provides OVE in the form of a rolling bar, wherein the first symbol array and the second symbol array are connected such that they provide sets of rolling bars. The first set of rolling strips is interleaved with the second set of rolling strips. When changing the point of view (POV) of the OVSD, for example by tilting, both sets of rolling bands appear to have changed or changed positions. It should be understood that the OVEs provided by the embodiments of the present invention are not limited to rolling bars, and that the OVEs obtained by changing the viewpoint are not limited to moving in a particular direction. For example, the first set of artificially generated images (eg, rolling stripes) may move in the first direction and the other set move in the other direction. In some embodiments according to the present invention, the rolling strips move orthoparallax (ie, perpendicular to the tilt direction). For example, the rolling strips can be configured to move in either direction as the viewer's point of view changes. For example, in some embodiments according to the present invention, lines were used for one of the layers, in which case the material (for design/movement purposes) acts as a lenticular material and moves only along one direction of inclination. However, the relative pitch/angle of the lines of the second layer can be adjusted to guide the movement of the moiré lines in many directions.

[65] As mentioned, in some embodiments according to the present invention, the OVSD provides OVE in the form of an artificial color. Artificial color in the context of the present invention encompasses an image color that is projected from a pigmented material forming part of one of the first character array or the second character array, wherein the color of the projected image includes at least one color that is different from the color of the pigmented material located in a character array. In a preferred embodiment, the character array is filled with or coated with a dark pigment that forms a first set of multicolor stripes, which are green stripes with yellow borders, and a second set of blue stripes interspersed between the first set. Adjusting the spacing between the first symbol layer and the second symbol layer results in different sets of colors for the rolling strips and their respective boundary portions. In some embodiments according to the present invention, the rolling strips do not have a separate boundary section, or the boundary section has the same color as the rolling strips with which it is connected.

[66] In some embodiments, various symbols are described in PCT/US2004/039315 issued by Steenblik et al., which is incorporated herein by reference. It is contemplated that the symbols may be spaces, columns, or a combination thereof. In some embodiments according to the present invention, the voids have parallel sides, whereby they do not taper on either side of the layer in which they are formed. In some embodiments according to the present invention, the voids have non-parallel sides, whereby they taper from at least one side of the layer to the other. In some embodiments, the implementation of the narrowing occurs from the outer layer to the inner layer. The characters may be formed in a variety of ways, including, for example, laser shaping, photolithography, machining, embossing, printing, casting, other molding techniques, or any combination thereof. In various embodiments, voids or columns are formed in the character layer by the use of pre-patterned embossing tools that form the voids. The character layer, in one or more embodiments, is an uncured embossed resin composition. The character layer is then cured and the embossing agent is removed. The voids in various embodiments according to the present invention are then filled with a contrast material, such as a pigment or a reflective material (eg, reflective metal, alloy, etc.). The term voids in the context of this document includes recesses and holes. Holes according to various embodiments of the present invention extend through at least one OVSD layer, with the recess according to some embodiments beginning and ending within one OVSD layer. At least two symbol layers may be generated simultaneously or sequentially and then connected. For example, in some embodiments according to the present invention, a first symbol prelayer is applied over a second symbol prelayer. In the context of the present invention, the term "preliminary" encompasses an indication that the symbol layer does not contain symbols necessary to form an artificially created image or artificial color. After applying the preliminary (which are, in some embodiments, polymeric) character layers on top of each other to form the pre-composite character laminate, the embossing means are brought into contact with opposite surfaces of the composite character laminate. It has been found that the alignment of the first character layer with the second character layer can be improved by simultaneous embossing. However, it is also contemplated herein that the first character layer may be embossed before the second character layer, or vice versa. The symbols may, in some embodiments, take on various forms of lines and dots, which themselves represent specific characters and/or are arranged as patterns of characters. The voids can be coated in a variety of ways, including, for example, electroplating, electroless plating, vapor deposition (e.g., chemical or physical vapor deposition), monomer vapor deposition, spraying, spin coating, roller coating, other coating methods, and any combination thereof.

[67] In some embodiments according to the present invention, the symbols comprise columns formed on or in the OVSD layer. In some embodiments according to the present invention, the columns are formed using an embossing or printing means that is configured to transfer a contrast material onto the surface of the OVSD substrate layer. In some embodiments according to the present invention, the columns are formed using a printing medium that provides high resolution lines or dots. It is contemplated that columns may take various forms within the scope of the present invention. However, the preferred shapes have been found to be flat components, projections or elevations.

[68] Observation of the OVE or artificial color can be done while viewing the OVSD from either side of the OVSD; from the side adjacent to the first symbol layer, or from the side adjacent to the second symbol layer; or both sides of the OVSD. In some embodiments according to the present invention, the OVE can be observed from one of the symbol layers. In some embodiments according to the present invention, the OVE can be observed from both the first symbol layer and the second symbol layer. It has been found useful that in polymer banknotes, the OVE OVSD can be observed from either side of the OVSD. In some embodiments, although the artificial image or artificial color can be observed from both sides, even when only one side has filled/covered symbols, it is preferable that the first symbol layer and the second symbol layer be equally filled/covered with a symbol. The artificially generated image, in some embodiments, is formed based on the interference provided by the symbol layer that is located next to the viewer. This interference may be provided when either or both of the symbol layers are filled, covered, or empty, or any combination thereof. For example, in some embodiments according to the present invention, the first symbol layer that is adjacent to the viewer has symbols that are empty spaces, and the second symbol layer that is further away from the viewer has symbols that are filled spaces. Coincidence of the first symbol layer with the second symbol layer creates two sets of interleaved rolling bands that change colors as the OVSD is tilted or the observer's viewpoint changes. In various embodiments, both the first symbol layer and the second symbol layer contain symbols that are partially filled or covered. Adjusting the coincidence and/or spacing may provide the desired OVE. Adjustment of the interval, repetition period, or character pattern, in some embodiments, may be performed to tune the system to provide the desired OVE.

[69] It is contemplated that, in embodiments according to the present invention, the connection of the first symbol layer to the second symbol layer may be direct or indirect. In some embodiments according to the present invention, the first symbol layer and the second symbol layer are connected to each other such that at least one optically variable effect is provided by the OVSD when viewed from at least one side of the OVSD. However, in some embodiments, additional components or layers are located between the first and second symbol layers. Although it is preferred that the first and second symbol layers are connected directly to each other, since the resulting OVSD may be thinner in such embodiments, in some embodiments a separate optical spacer layer is located between the first and second symbol layers. Preferably, the character layers and optical spacers have the same transparency or translucency and refractive index. However, in some embodiments, the character layers and/or the liner layer comprise different material compositions. Alternatively, it is also contemplated that an additional layer may be located on one or more of the outer surfaces of the composite symbol structure.

[70] In some embodiments, the OVSD is constructed such that the first symbol layer consists of filled columns and the second layer is left blank. In some embodiments, the sharpness and contrast of the artificially generated image can be further enhanced by the addition of a transparent material that is applied so that it partially fills the gaps between the columns in the second character layer. This material may be an additive used in the OVSD manufacturing step, it may be a clear filamentous adhesive, or even a liquid polymer applied in the papermaking step of the process. Examples of suitable transparent materials include, but are not limited to, polyvinyl alcohol, gelatin, or polyurethanes.

[71] In some embodiments, at least one of the first symbol layer and the second symbol layer acts as an interference layer. In at least one embodiment, the first symbol layer, which is adjacent to the viewer, contains symbols that are either empty or filled in a different pattern than the second symbol layer, which is remote from the viewer, and contains symbols that are columns of contrast material. The interference provided by the first layer creates an OVE when the OVSD is viewed from different viewpoints. Thus, it should be understood that the characters in the first character layer and the second character layer may be the same or may be different from each other, or may be the same and filled/covered differently or the same. While in this illustrative example, the first character layer included spaces and the second character layer included columns, the reverse is also within the scope of the present invention.

[72] Suitable characters and methods for their representation are described in International Patent Application Publication WO2005/052650, WO2006/125224, WO2008/008635, WO2011/019912, WO2011/163298, WO/2013/028534, WO2014/143980, WO27824/01824. WO2016/044372; WO2016/011249; WO2013/163287; WO2007/133613; In a preferred embodiment, the character layers are formed using a substantially transparent or transparent radiation-curable material, including but not limited to acrylics, polyesters, epoxies, urethanes, and the like. In various embodiments, the character arrays are formed using an acrylated urethane such as an acrylated urethane commercially available from Lord Chemicals under the trade designation U107. In some embodiments, each of the character recesses formed on the bottom flat surface of the optical spacer is from about 0.5 to about 8 µm deep and typically 30 µm in microimage or symbol width.

[73] The relief structures forming the image characters may, depending on the embodiments, have various sizes, including micro-size, nano-size, macro-size, or any combination thereof. While it is contemplated that nanoscale or macroscale would be appropriate, it is preferred that microscale image symbols be used. The inventors have found that some embodiments that use micro-sized image symbols exhibit relatively good manufacturability.

[74] In some embodiments according to the present invention, the OVSD comprises an optical spacer, wherein the first symbol layer and the second symbol layer are embedded on opposite sides of the optical spacer. Various optical spacers will be apparent in connection with the present invention to those skilled in the art. Accordingly, as the thickness of the optical spacer increases, changing viewpoints due to the tilt of the OVSD, for example, will cause the bands described in some embodiments to appear to change or roll faster. In various embodiments, the OVSD has a thickness of 50 µm or less (including less than 45 µm, 40 µm, and 35 µm). Surprisingly, it has been found that at a thickness of less than 30 µm, the OVE can still be perceived. This can be observed in particular in embodiments in which the OVE can be received from both sides of the OVSD. Interference is especially aided by the presence of contrast materials in the first and second character layers, which in turn improves OVE unexpectedly.

[75] Similarly, in various embodiments of the OVSD of the present invention, the additional components/layers include, but are not limited to, an optical spacer, a coating layer, a tie layer, a base embossed lacquer layer, a patterned metal layer, a reflective layer, an obscuration layer, a layer obtained vapor deposition, a structural color change layer, an anti-staining layer, a hardening layer, or a pigmented or colored layer. It is also contemplated that a plurality of microimage element arrays or image symbols are also embedded as part of the image projection system. Likewise, it is also contemplated that one or more additional symbol layers are located between the first and second symbol layers. While it has surprisingly been found that the need for a seal layer can be avoided by using two character layers without a lens layer, it should be understood that a seal layer is still provided and that embodiments of the present invention comprise OVSDs in which at least one of the first the character layer or the second character layer is partially or completely sealed. For example, in some embodiments, the liner occupies voids, particularly if the voids have empty space, and in other embodiments, the liner covers only the top surface of at least one of the first and second character layers. In other embodiments, the sealing layer covers all OVSDs.

[76] The artificially generated image projected by the OVSD is in some embodiments due to a mismatch of the first character array with respect to the second character array. In some embodiments according to the present invention, such a mismatch between the two arrays provides a moiré image.

[77] In some embodiments according to the present invention, the mismatch is associated with at least one of a size mismatch, a rotational mismatch, a periodic mismatch, or a zonal mismatch. In some embodiments according to the present invention, the symbols of the first symbol layer are substantially the same, but vary in size relative to the symbols of the second symbol layer, resulting in a size mismatch. Such size mismatch can also be achieved by resizing the symbols in the first symbol layer in a pattern that is different from the resizing scheme for symbols in the second symbol layer. In some embodiments according to the present invention, periodic mismatch is provided by having the symbols spaced equally in the first symbol layer, but at a different spacing than the spacing in the second symbol layer. Alternatively, the symbol spacing may not be the same in the first symbol layer, but the scheme is different from the symbol spacing scheme of the second symbol layer, resulting in intermittent mismatch. A zonal mismatch in some embodiments according to the present invention encompasses a first symbol layer containing symbols present in particular zones of the first symbol layer, and corresponding zones of the second symbol layer contain symbol zones having a different size, shape, or spacing.

[78] In some embodiments according to the present invention, a contrast material may be included in the character layer. In at least one embodiment, the voids are filled or covered with a contrast material. In some embodiments, some characters are filled and others are covered, whereby the character array contains both filled and covered characters. In some embodiments according to the present invention, the characters are voids that are covered with a contrast material such that less than 50% of the depth of the voids is occupied by the contrast material. Preferably, the material occupies less than 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10% and 5% of the void depth and takes the form of void boundaries including the base and sidewalls. In some embodiments according to the present invention, the symbols are voids that are filled with a contrast material such that 50% or more of the depth of the voids is occupied by the contrast material. Preferably, more than 60%, 70%, 80%, 90%, 95%, 99% of the void depth is occupied by the contrast material. The voids can be filled with any suitable contrast material such as pigmented resins, paints, dyes, metals or magnetic materials. In an exemplary embodiment, the voids are filled with a pigmented resin containing a submicron pigment, which is commercially available from Sun Chemical Corporation under the trade designation Spectra Pac.

[79] In some embodiments according to the present invention, the columns are printed with a contrast material or coated with a contrast material. The printing of columns, as mentioned herein, implies that the columns are formed by some printing means that provide high resolution columns, or that the columns are formed as continuous areas of relief structures by some high resolution embossing processes. If the columns are formed by a printing process, it is preferable that a contrast material be included in the printing medium (eg ink) thereby filling the columns. Alternatively, if the columns are formed by an embossing process, it is preferred that the contrast material be applied by means of a coating that covers the exposed sides of the columns.

[80] In some embodiments according to the present invention, both the first and second symbol layers contain symbols that are columns and/or spaces. In some embodiments according to the present invention, one of the first character array and the second character array contains columns, and the other of them contains voids. The voids or columns may be filled or covered as described above.

[81] Surprisingly, it has been found that some embodiments according to the present invention allow the use of a high resolution symbol generator to generate both the first symbol layer and the second symbol layer such that when they are superimposed, an OVE is created. High-resolution character generation tools were previously thought to cause registration problems for lens-based systems. Surprisingly, OVSD with both high-resolution symbol layers according to embodiments of the present invention not only provides for improved registration, but also allows artificially generated images and color to be projected, as well as OVE.

[82] In some embodiments, the present invention proposes the use of the OVSD disclosed herein to authenticate a valuable item. In some embodiments according to the present invention, an OVSD is coupled to an article of manufacture such that high resolution symbols are used to create an OVE. The connection of the OVSD to the valuable article may be effected by various adhesives, which will be apparent, in light of the present invention, to a person skilled in the art. For example, a suitable means of bonding the OVSD to the note substrate may be heat-activated or water-activated adhesives. Additionally or alternatively, the OVSD may be woven into the paper during manufacture of the banknote's paper substrate, whereby the OVSD is wholly or partly embedded in it (eg, windows). In another embodiment, the banknote substrate is polymeric, wherein the OVSD is bonded to at least one side of the banknote substrate. Alternatively, in some embodiments according to the present invention, the banknote polymer substrate functions as an optical spacer, whereby the first indicia layer is located on the first side of the substrate, while the second indicia layer is located on the second side of the substrate. In some embodiments according to the present invention, the OVSD acts 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 some embodiments according to the present invention, the OVSD is connected to a security label used to authenticate consumer products. The OVSD may be connected to the label as described herein for security documents (eg, banknotes).

[83] Various embodiments according to the present invention provide a method for obtaining OVSD, as described in this document. In some embodiments according to the present invention, this method includes: providing an optical spacer layer; forming a first character layer on a first side of the optical gasket layer as described herein, and likewise forming a second character layer on a second opposite side of the optical gasket; generating a character array on or in the first character layer and generating a second character array on or in the second character layer; the symbols are high-resolution symbols. Preferably, the first and second character arrays are generated simultaneously. However, in some embodiments according to the present invention, in which the symbols are recessed, they are formed sequentially and then attached to opposite sides of the optical spacer. The constituent layers (i.e., character layers, pad layers, etc.) are as described herein.

[84] In some embodiments of the method according to the present invention, the first symbol layer and the second symbol layer are connected to each other to create at least one OVE, such as rolling stripes, artificial color, or color change. The symbols are high resolution symbols having a width ranging from 0.6 µm to about 5.5 µm, or a spacing of less than about 7.7 µm.

[85] In some embodiments, a method for authenticating a valuable item is provided, wherein in some embodiments of the present invention, the method includes attaching an OVSD to the valuable item. Valuable item authentication includes inspection of the OVSD to verify that the specified OVE is correct.

[86] In another aspect of the present invention, a value article is provided, wherein in some embodiments according to the present invention, the value article comprises a substrate contact surface and an OVSD, wherein the OVSD is connected to the substrate contact surface.

[87] In another aspect, a banknote is provided, wherein the banknote comprises: (i) a substrate layer having a first side and a second opposite side; (ii) a first character layer having a first character array; (iii) a second character layer having a second character array; the symbols are high-resolution symbols. The first character layer and the second character layer are connected to each other to form a composite structure, whereby at least one optically variable effect is observed when the composite structure is viewed from at least one side of the composite structure. Preferably the OVE is selected from rolling strips, artificial color or color change. In some embodiments according to the present invention, OVE can be observed on both sides of the composite structure. In some embodiments according to the present invention, the substrate layer is at least one of a polymeric or cellulosic material.

[88] In some embodiments according to the present invention, the substrate layer is located between the first symbol layer and the second symbol layer. Alternatively, the optical spacer is positioned between the first character layer and the second character layer to form a composite structure which is then bonded to at least one of the first side or the second side of the substrate layer. In some embodiments of the present invention, the composite structure is in the form of an insert or filament that is surfaced, surfaced in a window, or embedded.

[89] The OVSD described herein will now be described in detail with reference to specific embodiments depicted in the accompanying drawings.

[90] FIG. 1 is a cross-sectional view of an OVSD that provides OVE, with no symbols filled or covered, in accordance with various embodiments of the present invention.

[91] Referring to the non-limiting example of FIG. 1 showing an OVSD 10. In some embodiments, the OVSD 10 includes an optical spacer 12 located between the first symbol layer 11 and the second symbol layer 13. The first symbol layer 11 contains an array of unfilled or uncovered symbols 11a. In the non-limiting example of FIG. 1, symbols 11a are indented lines, and the second symbol layer 13 contains an array of unfilled/uncovered symbols 13a in the form of indented dots. According to various embodiments, the symbols 11a and 13a are of high resolution, with the first symbol layer 11 and the second symbol layer 13 connected to each other and do not match to create an OVE.

[92] Although in the non-limiting example of FIG. 1, the symbols 11a in the first symbol layer 11 contain indented lines, and the symbols 13a in the second symbol layer 13 contain indented dots, it is also assumed that dots and lines can be interchanged, or that both symbol layers 11, 13 contain dots or lines, in in particular, such that dots in individual sections of the first symbol layer 11 overlap with dots in the second symbol layer 13, or that dots in the first symbol layer 11 overlap with lines in the second symbol layer 13, or that lines in the second symbol layer 13 overlap with dots in the first layer 11 symbols.

[93] In the examples of the manufactured OVSD according to the embodiments shown in FIG. 1, high resolution symbols 11a, 13a provide an OVSD that creates an OVE without a lens array, allowing such an OVSD to be used as an anti-counterfeiting device. In some embodiments, a lensless design, such as depicted in FIG. 1 allows you to create an OVE, simplify the manufacturing process and eliminate the problems that arise when registering characters with a lens structure. In addition, the operational advantages of a lensless OVSD such as shown in FIG. 1 include troubleshooting problems associated with contamination and damage to micro-optical lenses.

[94] FIG. 2 is a cross-sectional view of an OVSD that provides an OVE with the symbols of the first and second symbol layers covered, in accordance with some embodiments of the present invention.

[95] Referring to the non-limiting example of FIG. 2, which depicts an example of an OVSD 10. In some embodiments, an optical spacer 12 is positioned between the first symbol layer 11 and the second symbol layer 13. The first symbol layer and the second symbol layer 13 are in some embodiments indirectly connected and non-coincidently arranged such that the OVSD projects the OVE. In the example shown in FIG. 2, the symbols 13a, 11a are high resolution and have a coating 14a in the first symbol layer 11 and are coated in the second symbol layer 13. The coating 14a of the characters 11a, 13a can be applied in desired patterns, for example by coating the base of the characters 11a as in the first character layer 11, or by coating 14a on the base portions of the characters 13a of the second character layer 13, or by coating 14a on the ledges, as in the second layer of 13 characters.

[96] FIG. 3 is a cross-sectional view of an OVSD that provides an OVE, with the symbols of the second symbol layer filled, in accordance with some embodiments of the present invention.

[97] Referring to the non-limiting example of FIG. 3, which shows an example of an OVSD 10. According to various embodiments, an optical spacer 12 is positioned between the first symbol layer 11 and the second symbol layer 13. Each symbol layer 11, 13 contains portions having high resolution symbols 13a. In various embodiments, the symbols 11a of the first symbol layer 11 and the symbols 13a of the second symbol layer 13 are arranged in an array such that they do not match when rotated. According to the illustrative example in FIG. 3, the characters 13a of the second character layer 13 are filled with a filler 14b of contrast material. When viewed from the side adjacent to the first symbol layer 11, the OVE is seen as rolling stripes.

[98] FIG. 4 is a cross-sectional view of an OVSD that provides an OVE with the symbols of the first symbol layer filled and the symbols of the second symbol layer covered, in accordance with some embodiments of the present invention.

[99] Referring to the illustrative example in FIG. 4, which depicts an example of an OVSD according to various embodiments of the present invention. According to various embodiments, the optical spacer 12 is located between the first symbol layer 11 and the second symbol layer 13. As shown in this illustrative example, the character 11a in the first character layer 11 is filled with a contrast material filler 14b, and the characters in the second character layer 13 are covered with a patterned contrast material coating 14a that extends along a portion of the base and side of the recesses 13a. The first character layer 11 and the second character layer 13 are formed simultaneously on opposite sides of the optical spacer 12 and are non-matched to form an OVE.

[100] FIG. 5 is a cross-sectional view of an OVSD that provides OVE without a separate optical spacer and without filled or covered symbols, in accordance with various embodiments of the present invention.

[101] Referring to the non-limiting example of FIG. 5, which depicts an example of an OVSD 20. In some embodiments, the first symbol layer 21 is directly connected to the second symbol layer 23. In this illustrative example, there is no optical spacer between the first character layer 21 and the second character layer 23. Each of the first symbol layer 21 and the second symbol layer 23 has a symbol array 21a and 23a, respectively. The symbols 21a, 23a of the symbol layers 21, 23 are high resolution symbols and arranged without matching to create an OVE even if the symbols 21a, 23a are not filled or covered.

[102] FIG. 6 is a cross-sectional view of an OVSD that provides an OVE with the symbols of the first and second symbol layers recessed, in accordance with some embodiments of the present invention.

[103] Referring to the non-limiting example of FIG. 6, which depicts an example of an OVSD 30 according to various embodiments of the present invention. In some embodiments, the optical spacer 32 is positioned between the first symbol layer 31 and the second symbol layer 33. The first character layer 31 and the second character layer 33 are formed and then transferred to connect to opposite sides of the optical gasket 32. According to various embodiments, the high-resolution recesses in the first character layer 31 and the second character layer 33 are recessed such that their bases face the away from the optical gasket, and their tops face the optical gasket 32. The symbol arrays in the symbol layers 31, 33 do not match each other and contain high-resolution symbols 31a, 33a, respectively. As shown in the non-limiting example of FIG. 6, the contrast material is placed as a cover 34a in the depressions.

[104] FIG. 7 is a cross-sectional view of the OVSD that OVE provides, with the symbols of the first symbol layer being columns that are covered or filled, and the symbols of the second symbol layer being filled voids, in accordance with various embodiments of the present invention.

[105] Referring to the non-limiting example of FIG. 7, which depicts an OVSD 40 according to various embodiments of the present invention. In some embodiments of the OVSD 40, the optical spacer 42 is positioned between the first symbol layer 41 and the second symbol layer 43. As shown in this illustrative example, the first character layer 41 contains high-resolution columns that are coated 44a and filled (eg, by printing) with filler 44b. The second symbol layer 43 contains high resolution pits which are filled with filler 44b. The first symbol layer 41 and the second symbol layer 43 do not match each other to provide an artificial color that changes as the OVSD viewpoint changes.

[106] FIG. 8 is a cross-sectional view of the OVSD that OVE provides, with the symbols of the first symbol layer being columns that are covered or filled, and the symbols of the second symbol layer being columns that are covered, in accordance with some embodiments of the present invention.

[107] Referring to the non-limiting example of FIG. 8, which depicts the OVSD 50. In some embodiments, in the OVSD 50, an optical spacer 52 is positioned between the first symbol layer 51 and the second symbol layer 53. The first symbol layer 51 and the second symbol layer 53 both contain columns in respective high resolution symbol arrays. The columns in the first character layer contain infills (eg, material deposited by the printing process) 54b and coatings 54a, and the columns in the second character layer 53 contain pattern coatings 54a that extend along the side of the columns and apex portions. The first symbol layer 51 and the second symbol layer do not match each other to create an OVE that can be observed from both sides of the OVSD.

[108] FIG. 9 is a cross-sectional view of the OVSD that OVE provides, with the symbols of the first symbol layer being covered and the symbols of the second symbol layer being filled columns, in accordance with some embodiments of the present invention.

[109] Referring to the non-limiting example of FIG. 9 showing the OVSD 50. In various embodiments, in the OVSD 50, the optical spacer 52 is positioned between the first symbol layer 51 and the second symbol layer 53. In this illustrative example, the first symbol layer 51 and the second symbol layer 53 both contain columns in respective high resolution symbol arrays. The columns in the first character layer 51 contain padding 54b covering the sides and top of the columns, and the columns in the second character layer 53 contain overlays 54a, which are printed in some embodiments. The optical spacer 52 can be adjusted appropriately to increase the OVE speed. The first symbol layer and the second symbol layer do not match each other to create an OVE.

[110] FIG. 10 is a sectional isometric view of an OVSD that includes first and second symbol layers with covered symbols and that provides rolling bar OVE, in accordance with some embodiments of the present invention.

[111] Referring to the non-limiting example of FIG. 10, which is an isometric view of the OVSD 60. In some embodiments, in the OVSD 60, an optical spacer 62 is positioned between the first symbol layer 61 and the second symbol layer 63. In various embodiments, the optical spacer 62 has a thickness of approximately 30 microns. As shown in this illustrative example, the high resolution character arrays in the first character layer 61 and in the second character layer 63 are coated with a contrast material (eg, coating) 64b. The first symbol layer 61 and the second symbol layer 63 in various embodiments do not match each other to create an OVE. In the non-limiting example shown in FIG. 10, OVE includes sets of rolling strips 65, 66 in which at least one color differs from that of the contrast material. As shown in this non-limiting example, the first set of rolling strips 65 includes a border 65a.

[112] FIG. 11 is a sectional isometric view of an OVSD in a "rolling band" OVE banknote, in accordance with some embodiments of the present invention.

[113] Referring to the non-limiting example of FIG. 11, which depicts an item of value 70 that contains an OVSD 60. In this illustrative example, the item of value 70 is a bank note. In various embodiments, the OVSD 60 provides an OVE that includes a first set of rolling strips 65 and a second set of rolling strips 66. In various embodiments, the first set of rolling strips 65 further comprises one or more visible borders 65a.

[114] FIG. 12 shows a cross-sectional view of an OVSD according to various embodiments of the present invention, wherein the first symbol layer comprises filled columns and the second symbol layer is partially filled with a second, transparent material such that the areas between the columns are only partially filled.

[115] Referring to the non-limiting example of FIG. 12, which depicts an OVSD 80. In various embodiments, the OVSD 80 comprises a first symbol layer 81 (e.g., first symbol layer 11 in FIG. 1), an optical spacer layer 82 (e.g., optical spacer layer 12 in FIG. 1), and a second character layer 83 (eg, character layer 13 in FIG. 1). As shown in the non-limiting example of FIG. 12, one or more image symbols of the second symbol layer 83 are filled with a contrast material 84 (eg, contrast material 14b in FIG. 3). Further, in some embodiments, the image symbols of the first symbol layer 81 are partially filled with a transparent material 85, which in some embodiments contributes to the sharpness and contrast of the OVE provided by the OVSD 80.

[116] Examples of OVSDs according to some embodiments of the present invention include an OVSD comprising a first symbol layer, containing a first symbol array, a second symbol layer coupled to the first symbol layer, and comprising a second symbol array, wherein the symbols of the first symbol layer and the second the symbol layers are lines, dots, or a combination thereof, and the symbols of one or more of the first symbol layer or the second symbol layer exhibit high resolution.

[117] Examples of OVSDs according to some embodiments of the present invention include an OVSD in which at least one of the first symbol layer and the second symbol layer is an interference layer.

[118] Examples of OVSDs according to some embodiments of the present invention include an OVSD in which a first symbol layer and a second symbol layer are connected to each other such that at least one OVE is provided by the OVSD when the symbols in one of the first or second symbol layers are viewed from at least one side of the OVSD that is adjacent to another symbol layer.

[119] Examples of OVSDs according to some embodiments of the present invention include an OVSD in which the OVE includes rolling strips.

[120] Examples of OVSDs according to some embodiments of the present invention include an OVSD in which the rolling strips are multicolored.

[121] Examples of OVSDs according to some embodiments of the present invention include an OVSD in which the OVE includes artificial color.

[122] Examples of OVSDs according to some embodiments of the present invention include an OVSD in which the OVE can be observed from a first viewpoint with the first symbol layer facing the viewer, and from a second viewpoint with the second symbol layer facing the viewer.

[123] Examples of an OVSD according to some embodiments of the present invention include an OVSD further comprising a transparent material partially filling the area between columns in at least one of the first character layer or the second character layer.

[124] Examples of OVSDs according to some embodiments of the present invention include an OVSD in which the symbols of at least one of the first character array and the second character array have one or more of a width size in the range of 0.5 μm to 6.5 µm or character spacing less than 7.7 µm.

[125] Examples of OVSDs according to some embodiments of the present invention include an OVSD in which the characters of both the first character array and the second character array include one or more of the spaces or columns.

[126] Examples of OVSD according to some embodiments of the present invention include OVSD, in which the voids include one or more of the recesses or holes.

[127] Examples of OVSDs according to some embodiments of the present invention include an OVSD in which the columns include one or more of planar components, protrusions, or elevations.

[128] Examples of OVSD according to some embodiments of the present invention include OVSD, in which high resolution provides for a line width of 0.5 μm to 5.0 μm.

[129] Examples of OVSD according to some embodiments of the present invention include OVSD, in which high resolution provides a line spacing from 0.5 μm to 5.0 μm.

[130] Examples of OVSDs according to some embodiments of the present invention include an OVSD in which high resolution provides for a dot width of 0.5 µm to 6.5 µm.

[131] Examples of OVSDs according to some embodiments of the present invention include an OVSD in which one or more of the first character array or the second character array has a pitch of 1.0 µm to 6.5 µm.

[132] Examples of OVSD according to some embodiments of the present invention include OVSD, in which high resolution provides a dot spacing of 0.5 µm to 5.0 µm.

[133] Examples of OVSDs according to some embodiments of the present invention include an OVSD further comprising an optical spacer between the first symbol layer and the second symbol layer.

[134] Examples of OVSDs according to some embodiments of the present invention include an OVSD in which a first character array and a second character array are arranged to provide a mismatch between the first character array and the second character array.

[135] Examples of OVSDs according to some embodiments of the present invention include an OVSD in which the mismatch includes one or more of size mismatch, rotational mismatch, periodic mismatch, or zonal mismatch.

[136] Examples of OVSD according to some embodiments of the present invention include an OVSD in which the OVE is provided when the observer's viewpoint changes relative to the OVSD.

[137] Examples of OVSDs according to some embodiments of the present invention include an OVSD in which the symbols of at least one of the first symbol layer and the second symbol layer are filled or coated with a contrast material.

[138] Examples of OVSDs according to some embodiments of the present invention include an OVSD in which symbols of at least one of the first symbol layer and the second symbol layer include columns containing a contrast material.

[139] Examples of OVSDs according to some embodiments of the present invention include an OVSD in which symbols in a first symbol layer and symbols in a second symbol layer are generated by means for creating symbols.

[140] Examples of OVSDs according to some embodiments of the present invention include an OVSD in which a first symbol layer and a second symbol layer are embedded as opposite sides of the optical spacer.

[141] Examples of some embodiments of the present invention include the use of the OVSD of the present invention to authenticate a valuable item.

[142] Examples of a method for producing an OVSD according to some embodiments of the present invention include providing an optical spacer layer, applying a first character layer on a first side of the optical spacer layer, and applying a second character layer on a second side of the optical spacer layer, and forming an array of characters on or in the first layer. symbols and forming a second array of symbols on or in the second symbol layer, wherein the symbols are high resolution symbols, and wherein the second side is opposite the first side of the optical spacer layer.

[143] Examples of a method for producing OVSD according to some embodiments of the present invention include methods in which the first symbol layer and the second symbol layer provide an optically variable effect.

[144] Examples of a method for producing OVSD according to some embodiments of the present invention include methods in which the optically variable effect includes one or more of rolling bands, artificial color, or color change.

[145] Examples of a method for producing an OVSD according to some embodiments of the present invention include methods in which high resolution symbols have a width in the range of about 0.5 µm to about 6.5 µm, or a spacing of less than about 7.7 µm.

[146] Examples of a banknote according to some embodiments of the present invention include banknotes comprising a substrate layer having a first side and a second opposite side, a first character layer having a first character array, a second character layer having a second character array, wherein the characters the first symbol layer and the second symbol layer are high resolution symbols; and wherein the first symbol layer and the second symbol layer provide an optically variable effect (OVE).

[147] Examples of a banknote according to some embodiments of the present invention include banknotes in which the first symbol layer and the second symbol layer are connected to each other to form a composite structure, whereby at least one optically variable effect is observed when the composite structure is viewed. on at least one side of the composite structure.

[148] Examples of a banknote according to some embodiments of the present invention include banknotes in which the optically variable effect includes one or more of a set of rolling bands, artificial color, or color change.

[149] Examples of banknotes according to some embodiments of the present invention include banknotes in which an optically variable effect can be observed on both sides.

[150] Examples of a banknote according to some embodiments of the present invention include banknotes in which the substrate layer is at least one of a polymeric or cellulosic material.

[151] Examples of a banknote according to some embodiments of the present invention include banknotes in which the substrate layer is located between the first symbol layer and the second symbol layer.

[152] Examples of a banknote according to some embodiments of the present invention include banknotes in which an optical spacer is located between the first character layer and the second character layer to form a composite structure that is connected to at least one of the first side or the second side of the substrate layer.

[153] Examples of banknotes according to some embodiments of the present invention include banknotes further comprising an insert or thread that is surface applied, surfaced in a window, or embedded.

[154] Although the present invention has been described with various embodiments, various changes and modifications can be made to those skilled in the art. The present invention is intended to cover such changes and modifications as fall within the scope of the appended claims.

[155] Nothing in the present invention should be construed as implying that any particular element, step, or function is an essential element, step, or function to be included within the scope of the claims. The scope of the subject matter to be patented is determined only by the claims. Moreover, nothing in the claims refers to 35 U.S.C. § 112(f), unless the exact words "means for" are followed by a participle.

Claims (62)

1. An optically variable protective device, comprising: substrate, and the substrate contains: a first character layer containing a first character array; and a second character layer connected to the first character layer and containing a second character array, wherein the symbols of the first symbol layer and the second symbol layer are lines, dots, or a combination thereof, wherein the symbols of one or more of the first symbol layer or the second symbol layer exhibit one or more of line width, line spacing, or point width containing high resolution, wherein the symbols of the first symbol layer contain voids on the first side of the substrate, and the symbols of the second symbol layer contain voids on the second side of the substrate, and wherein the first symbol layer and the second symbol layer provide at least one optically variable effect when viewing one side of the optically variable security device. 2. An optically variable security device according to claim 1, characterized in that at least one of the first symbol layer and the second symbol layer is an interference layer. 3. An optically variable security device according to claim 1, characterized in that the optically variable effect includes rolling strips. 4. An optically variable security device according to claim 3, characterized in that the rolling strips are multi-coloured. 5. An optically variable security device according to claim 1, characterized in that the optically variable effect includes a color change. 6. An optically variable security device according to claim 1, characterized in that the optically variable effect includes an artificial color. 7. An optically variable security device according to claim 1, characterized in that the optically variable effect can be observed from a first viewpoint, with the first symbol layer facing the viewer, and from a second viewpoint, with the second symbol layer facing the viewer. 8. The optically variable security device of claim 1, further comprising a transparent material partially filling an area between columns in at least one of the first character layer or the second character layer. 9. An optically variable security device according to claim 1, wherein the symbols of at least one of the first symbol array and the second symbol array have one or more of the following: size in width ranging from 0.5 µm to 6.5 µm, or the size of the interval between characters is less than 7.7 microns. 10. An optically variable security device according to claim 1, wherein the symbols of both the first symbol array and the second symbol array include columns. 11. An optically variable security device according to claim 1, characterized in that the voids include one or more of the recesses or holes. 12. An optically variable security device according to claim 10, wherein the columns include one or more of planar components, protrusions, or elevations. 13. An optically variable security device according to claim 1, characterized in that the high resolution provides for a line width of 0.5 µm to 5.0 µm. 14. An optically variable security device according to claim 1, characterized in that the high resolution provides a line spacing of 0.5 µm to 5.0 µm. 15. An optically variable security device according to claim 1, characterized in that the high resolution provides for a dot width of 0.5 µm to 6.5 µm. 16. The optically variable security device of claim 1, wherein one or more of the first character array or the second character array has a pitch of 1.0 µm to 6.5 µm. 17. An optically variable security device according to claim 1, characterized in that the high resolution provides for a dot spacing of 0.5 µm to 5.0 µm. 18. The optically variable security device of claim 1, further comprising an optical spacer between the first symbol layer and the second symbol layer. 19. An optically variable security device according to claim 1, characterized in that the first character array and the second character array are arranged to provide a mismatch between the first character array and the second character array. 20. An optically variable security device according to claim 19, wherein the mismatch includes one or more of dimensional mismatch, rotational mismatch, periodic mismatch, or zonal mismatch. 21. An optically variable security device according to claim 1, characterized in that the optically variable effect is provided when the observer's point of view changes relative to the optically variable security device. 22. An optically variable security device according to claim 1, characterized in that the symbols of at least one of the first symbol layer and the second symbol layer are filled or coated with a contrast material. 23. An optically variable security device according to claim 1, wherein the symbols of at least one of the first symbol layer and the second symbol layer include columns containing a contrast material. 24. An optically variable security device according to claim 1, characterized in that the symbols in the first symbol layer and the symbols in the second symbol layer are formed by means for generating symbols. 25. An optically variable security device according to claim 1, characterized in that the first character layer and the second character layer are embedded as opposite sides of the optical spacer. 26. The use of an optically variable security device according to claim 1 to confirm the authenticity of a valuable item. 27. A method for producing an optically variable protective device according to claim 1, comprising: providing a substrate; applying a first indicia layer to a first side of the substrate and applying a second indicia layer to a second side of the substrate; and generating a character array on or in the first character layer and generating a second character array on or in the second character layer, wherein the symbols are high resolution symbols, and wherein the second side is opposite the first side of the substrate. 28. The method of claim 27, wherein the first symbol layer and the second symbol layer provide an optically variable effect. 29. The method of claim 28, wherein the optically variable effect includes one or more of rolling bands, artificial color, or color change. 30. The method of claim 27, wherein the high resolution symbols have a width in the range of 0.5 µm to 6.5 µm, or an interval of less than 7.7 µm. 31. An optically variable security device according to claim 1, characterized in that the optically variable security device is made by the method according to claim 27. 32. A method for authenticating a valuable article by connecting an optically variable security device according to claim 1 to a valuable article. 33. An article of value comprising an optically variable security device according to claim 1 and a contact surface of the substrate, the optically variable security device being connected to the contact surface of the substrate. 34. The method according to claim 32, characterized in that the item of value is a banknote. 35. Banknote containing: a substrate layer having a first side and a second opposite side; a first character layer having a first character array; and a second character layer having a second character array; wherein the symbols of the first symbol layer and the second symbol layer are high resolution symbols, wherein the first symbol layer and the second symbol layer provide an optically variable effect, and wherein the symbols of the first symbol layer and the second symbol layer contain voids. 36. Banknote according to claim 34, characterized in that the first symbol layer and the second symbol layer are connected to each other to form a composite structure, as a result of which an optically variable effect is observed when the composite structure is viewed from at least one side of the composite structure. 37. Banknote according to claim 34, characterized in that the optically variable effect includes one or more of a set of rolling stripes, artificial color or color change. 38. Banknote according to claim 35, characterized in that the optically variable effect can be observed from both sides of the banknote. 39. Banknote according to claim 35, characterized in that the substrate layer is at least one of a polymeric or cellulose material. 40. Banknote according to claim 35, characterized in that the substrate layer is located between the first symbol layer and the second symbol layer. 41. Banknote according to claim 35, characterized in that the optical spacer is located between the first character layer and the second character layer to form a composite structure that is connected to at least one of the first side or the second side of the substrate layer. 42. The banknote of claim 34, further comprising one or more of surfaced, windowed, or embedded insert or thread.

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