Micro-Optical Security Device with Color Zones - Patent application

Abstract

The micro-optical security device (100) with zone-by-zone color transitions includes a planar array of light-collecting elements (140) and a graphical icon layer (120) having a plurality of retaining structures (710) defining isolated volumes at a first depth within the graphical icon layer. The security device further includes a first zone (350) of graphical icons, the first zone of graphical icons having a first predetermined subset of the plurality of retaining structures comprising a hardened coloring material of a first color. The micro-optical security device also includes a second zone (360) of graphical icons comprising a second predetermined subset of the plurality of retaining structures, the isolated volumes of the retaining structures of the second predetermined subset of the plurality of retaining structures comprising a hardened coloring material of a second color, the second color contrasting with the first color.

Description

[Technical field]

[0001] The present disclosure relates generally to anti-counterfeiting of security and / or high value documents such as banknotes, passports and tickets, etc. More specifically, the present disclosure relates to micro-optical security devices having zones of color. [Background technology]

[0002] Micro-optical security devices, i.e., devices comprising arrays of microscale light-collecting elements and arrangements of image icons (e.g., sub-microscale regions of colored material) in the focal planes of the light-collecting elements that cooperate to produce one or more distinctive visual effects (e.g., a composite image having a three-dimensional appearance), have proven generally effective in providing reliable visual indicia of the authenticity of valuable documents such as currency and passports.

[0003] The performance and effectiveness of a micro-optical security device as a visual level indicator (i.e., detectable by the human eye, not by banknote equipment manufacturer ("BEM") devices or other specialized machinery) of a document's authenticity may depend, at least in part, on the extent to which the micro-optical security device produces visual effects that visually grab a user's attention, and on how flexible and amenable the appearance of the security device and the visual effects produced by the security device are to updates and modifications. For example, composite images with dull colors or blurry features (as may occur when the image icon layer is out of focus) are likely to be overlooked by users, increasing the likelihood that counterfeit notes will be distributed unnoticed. Similarly, if changes to the security device require costly or time-consuming restructuring of the manufacturing process, the intervals between updates and modifications of security devices used on security documents (e.g., banknotes) will be longer, providing malicious individuals with more time and opportunity to prototype and develop counterfeits.

[0004] Thus, making micro-optical security devices more visually appealing and processes for making such devices more amenable to dynamic adjustment and redesign remain a source of technical challenges and opportunities for improvement in the field of micro-optical security devices and methods for their manufacture. Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides a micro-optical security device having zones of color. [Means for solving the problem]

[0006] In a first embodiment, a micro-optical security device having zonal color transitions comprises a planar array of light focusing elements; a pictorial icon layer including a plurality of holding structures, the plurality of holding structures defining isolated volumes of a first depth within the pictorial icon layer; a first zone of the pictorial icon including a first predetermined subset of the plurality of holding structures, the isolated volumes of the holding structures of the first predetermined subset of the plurality of holding structures comprising hardened color material of a first color; and a second zone of the pictorial icon including a second predetermined subset of the plurality of holding structures, the isolated volumes of the holding structures of the second predetermined subset of the plurality of holding structures comprising hardened color material of a second color, the second color contrasting with the first color.

[0007] In a second embodiment, a method of making a micro-optical security device includes applying a layer of uncured colorant material of a first color to a graphical icon layer of the micro-optical security device, the graphical icon layer including a plurality of retaining structures defining isolated volumes of a first depth within the graphical icon layer, and scraping the graphical icon layer such that the uncured colorant material of the first color remains in the retaining structures of the graphical icon layer at a depth equal to or less than the first depth. The method further includes selectively curing the layer of uncured colorant material of the first color by directing a first pattern of light at a first zone of the graphical icon layer to form a first array of graphical icons, and removing the uncured colorant material of the first color.

[0008] In a third embodiment, a method of manufacturing a micro-optical security device includes selectively applying a first amount of uncured pigment material of a first color to a first region of a pictorial icon layer of the micro-optical security device, the pictorial icon layer including a plurality of retaining structures defining isolated volumes of a first depth within the pictorial icon layer. The method further includes selectively applying a second amount of uncured pigment material of a second color to a second region of the pictorial icon layer of the micro-optical security device, the second amount of uncured pigment material of the second color contacting at least a portion of the first region along a wetted boundary of a surface of the pictorial icon layer, and scraping the pictorial icon layer such that the uncured pigment material of the first color is substantially confined to the retaining structures of the first zone of the pictorial icon layer and the uncured pigment material of the second color is substantially confined to the retaining structures of the second zone of the pictorial icon layer. The method also includes curing the uncured colorant material of the first color and the uncured colorant material of the second color, wherein the first zone of the graphical icon layer and the second zone of the graphical icon layer abut along an area of ​​the graphical icon layer proximate the location of the wet boundary.

[0009] Other technical features will be readily apparent to those skilled in the art from the following drawings, descriptions and claims.

[0010] Before beginning the detailed description below, it may be convenient to set forth definitions of certain words and phrases used throughout this patent document. The term "coupled" and its derivatives refer to any direct or indirect communication between two or more elements, whether or not those elements are in physical contact with one another. The terms "including" and "comprising" and their derivatives refer to an open-ended inclusion. The term "or" is inclusive and / or. The phrase "related to" and its derivatives refer to including, contained within, interconnected with, containing, housed in, connected to, coupled to, communicable with, cooperate with, sandwiched between, juxtaposed with, adjacent to, coupled to, having, having a characteristic of, relating to, and the like. The functionality associated with a particular controller may be centralized or distributed, whether locally or remotely. The phrase "at least one of," 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 only one item in the list may be required. For example, "at least one of A, B, and C" includes any of the combinations A, B, C, A and B, A and C, B and C, and A and B and C.

[0011] Definitions of other specific phrases are provided throughout this patent document, and those of skill in the art will understand that in many, if not most, cases such definitions apply to the prior and future uses of the words and phrases so defined.

[0012] For a more complete understanding of the present disclosure and its advantages, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: [Brief description of the drawings]

[0013] [Figure 1] 1 illustrates an example of a micro-optical system in accordance with certain embodiments of the present disclosure. [Figure 2A]1 illustrates an exploded top perspective view of a micro-optical cell within a micro-optical security device according to certain embodiments of the present disclosure. [Figure 2B] 1 illustrates an exploded perspective view from below of a micro-optical cell within a micro-optical security device according to certain embodiments of the present disclosure. [Figure 3A] 1 illustrates aspects of the structure and manufacture of a section of a structured image icon layer according to various embodiments of the present disclosure. [Figure 3B] 1 illustrates aspects of the structure and manufacture of a section of a structured image icon layer according to various embodiments of the present disclosure. [Figure 3C] 1 illustrates aspects of the structure and manufacture of a section of a structured image icon layer according to various embodiments of the present disclosure. [Figure 3D] 1 illustrates aspects of the structure and manufacture of a section of a structured image icon layer according to various embodiments of the present disclosure. [Figure 3E] 1 illustrates aspects of the structure and manufacture of a section of a structured image icon layer according to various embodiments of the present disclosure. [Figure 3F] 1 illustrates aspects of the structure and manufacture of a section of a structured image icon layer according to various embodiments of the present disclosure. [Figure 4] 1 illustrates aspects of an apparatus for zonally curing areas of uncured pigmented material, according to various embodiments of the present disclosure. [Diagram 5] 13A-13D illustrate operations of a method for manufacturing a zone-hardened micro-optical security device according to various embodiments of the present disclosure. [Figure 6A] 1 illustrates aspects of the structure and manufacture of a section of a structured image icon layer according to various embodiments of the present disclosure. [Figure 6B] 1 illustrates aspects of the structure and manufacture of a section of a structured image icon layer according to various embodiments of the present disclosure. [Figure 6C] 1 illustrates aspects of the structure and manufacture of a section of a structured image icon layer according to various embodiments of the present disclosure. [Figure 6D]1 illustrates aspects of the structure and manufacture of a section of a structured image icon layer according to various embodiments of the present disclosure. [Figure 6E] 1 illustrates aspects of the structure and manufacture of a section of a structured image icon layer according to various embodiments of the present disclosure. [Figure 7] 13 illustrates an example of preserving sharp color transitions between zones in an image icon layer, according to certain embodiments of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] 1-7 described below and the various embodiments used to illustrate the principles of the present disclosure in this patent document are merely for illustrative purposes and should not be construed as limiting the scope of the present disclosure.

[0015] FIG. 1 illustrates an example of a micro-optical system 100 in accordance with certain embodiments of the present disclosure.

[0016] Referring to the non-limiting example of FIG. 1, the micro-optical system 100 includes, at a basic level, a planar array of focusing elements 105 (including, for example, focusing element 107) and an array of image icons 120 (including, for example, image icon 121). According to various embodiments, each focusing element of the planar array of focusing elements 105 has a footprint in which one or more image icons of the array of image icons 120 are located. In certain embodiments, the location of the image icons within each footprint of each focusing element in the array of image icons 120 corresponds to the space between the holding structures in the image icon layer. According to some embodiments, the ratio of the resolution of the planar array of focusing elements 105 (e.g., the number of focusing elements provided in a specified area, such as a 1×1 mm box) to the resolution of the array of image icons 120 (e.g., the number of focusing elements provided in a specified area) is equal to or greater than 1. As a non-limiting example, each image icon in the array of image icons 120 may belong to the footprints of multiple focusing elements. As a further non-limiting example, not all focusing elements in a specified region have a graphic icon within their footprint. Additionally, in some embodiments according to the present disclosure, the ratio of the resolution of the planar array of focusing elements 105 to the resolution of the array of graphic icons 120 may have a value less than 1. As a non-limiting example, there may be multiple graphic icons within a particular focusing element's footprint. In other words, zones of zone-wise cured pigmented material according to embodiments of the present disclosure can be sub- and multi-focus element scale. As used in this disclosure, "uncured pigmented material" encompasses polymer inks, pigmented polymers, and dye-based inks that transition from a wet uncured state to a more rigid dry state upon chemical reaction induced by irradiation with a curing light (e.g., ultraviolet curing light).

[0017] According to certain embodiments, the plurality of focusing elements 105 comprises a planar array of micro-optic focusing elements. In some embodiments, the focusing elements of the planar array of focusing elements 105 comprise micro-optic refractive focusing elements (e.g., plano-convex or GRIN lenses) having lens surfaces that provide a curved interface between regions of different refractive index (e.g., polymer lens material and air). The refractive focusing elements of the planar array of focusing elements 105 are fabricated from a photocurable resin having a refractive index in the range of 1.35-1.7 in some embodiments, and have diameters in the range of 5 μm-200 μm. In various embodiments, the focusing elements of the planar array of focusing elements 105 comprise reflective focusing elements (e.g., very small concave mirrors) with diameters ranging from 5 μm-50 μm. In this illustrative example, the focusing elements of the planar array of focusing elements 105 are shown as comprising circular plano-convex lenses, although other refractive lens shapes, such as lenticular lenses, are possible and within the contemplation of the present disclosure.

[0018] As shown in the illustrative example of FIG. 1, the array of image icons 120 includes a set of image icons (including image icon 121) arranged at predetermined locations within the footprint of the focusing elements of the planar array of light focusing elements 105. According to various embodiments, the individual image icons of the array of image icons 120 include areas of photocured material in a zoned manner in spaces defined by the retaining structures of the structured image icon layer. As used in this disclosure, the term "structured image layer" encompasses a layer of material (e.g., photocurable resin) that is embossed or otherwise formed to include structures (e.g., recesses, posts, grooves, or mesas) for positioning and retaining the image icon material. According to certain embodiments, the array of image icons 120 is constructed to facilitate dynamic redesign and reconfiguration of the image icon structures of the micro-optical security device 100. For example, the array of image icons 120 is formed in some embodiments by selectively filling and curing the retaining structures (e.g., square wells as shown in FIG. 1) with uncured pigmented material of one or more colors to create areas or zones of color within the array of image icons 120. In this non-limiting example, different colors in the array of image icons 120 are represented by different fill patterns on the surface of the image icon closest to the light collection layer, for example, image icon 121 is shown as having the same color as the image icons in its row.

[0019] As shown in the illustrative example of FIG. 1, in certain embodiments, the micro-optical system 100 includes an optical spacer 110. According to various implementations, the optical spacer 110 includes a film of a substantially transparent material that functions to position the graphical icons of the array of graphical icons 120 in or around the focal plane of the focusing elements of the planar array of focusing elements 105. In certain embodiments according to the present disclosure, the optical spacer 110 includes a fabrication substrate on which one or more layers of a photocurable material can be applied, embossed, and flood cured to form a holding structure, which can then be filled with a zone-by-zone cured pigmented photocurable material. As used in this disclosure, the term "filled" in the context of filling a holding structure of a graphical icon layer encompasses both filling all of the available volume of the holding structure with uncured pigmented material, and also filling a majority (e.g., 50-80 percent) of the available volume of the holding structure with uncured material. In certain embodiments, the photocurable material used to form the array of graphical icons 120 is an ultraviolet (UV) curable pigmented polymer.

[0020] In certain embodiments according to the present disclosure, the micro-optical system 100 includes a sealing layer 140. According to certain embodiments, the sealing layer 140 includes a thin (e.g., 2 μm to 50 μm thick) layer of a substantially transparent material that interfaces with the focusing elements of the planar array of focusing elements 105 at its lower surface, and includes an upper surface that has less variation in curvature than the planar array of focusing elements 105 (e.g., by being smooth or having a surface with a larger radius of curvature of localized relief than the focusing elements).

[0021] As shown in the non-limiting example of FIG. 1, in certain embodiments, the micro-optical system 100 can be attached to a substrate 150, for example by an adhesive layer 130, to form a security document 160. According to various embodiments, the substrate 150 can be a sheet of paper money or a polymer substrate. According to some embodiments, the substrate 150 is a thin flexible sheet of biaxially oriented polypropylene (BOPP), which is a polymer film. In various embodiments, the substrate 150 is a piece of synthetic paper material, such as Teslin®. According to some embodiments, the substrate 150 is a piece of polymer card material, such as a polyethylene terephthalate (PET) blank of the type suitable for making credit cards and driver's licenses.

[0022] 2A and 2B (collectively "FIG. 2") show exploded top and bottom perspective views of a micro-optical cell 200 within a micro-optical security device (e.g., micro-optical security device 100 of FIG. 1) according to certain embodiments of the present disclosure. As used in this disclosure, the term "micro-optical cell" encompasses a three-dimensional section of a micro-optical security device that corresponds to a single focusing element within a planar array of focusing elements (e.g., planar array of focusing elements 105 of FIG. 1). For convenience, structures of micro-optical cell 200 that are recognizable in both the top view presented in FIG. 2A and the bottom view presented in FIG. 2B are similarly numbered.

[0023] Referring to the non-limiting example of FIG. 2, the micro-optical cell 200 is one of a plurality (in some embodiments, millions) of micro-optical cells that form a micro-optical security device (e.g., the micro-optical security device 100 of FIG. 1). According to various embodiments, the micro-optical cell 200 includes a focusing element 207. In this illustrative example, the focusing element 207 is a refractive focusing element (in this case a plano-convex lens) that is formed by applying a layer of photocurable material to an optical spacer layer 210 (e.g., a layer of transparent film material that also serves as a manufacturing substrate), embossing the layer to define the shape of the focusing element 207 and, in some embodiments, additional optical spacers 201 (sometimes referred to as "goo spacers"), and then curing the material with light (e.g., UV light) to effect one or more chemical curing reactions to create a layer of material that is robust enough for use in a micro-optical security device.

[0024] According to various embodiments, the micro-optical cell 200 further comprises a section 220 of a structured graphical icon layer (e.g., a graphical icon layer including the array 120 of graphical icons of FIG. 1). Referring to the non-limiting example of FIG. 2, the section 220 of the structured graphical icon layer includes a plurality of retaining structures (e.g., retaining structures 230), each of which defines an isolated volume having a first depth (e.g., depth 235). In various embodiments according to the present disclosure, the graphical icon layer including the section 220 is constructed using a manufacturing technique similar to that of the light concentrating element 207, in which a layer of uncured photocurable material is applied to a surface of the optical spacer 210, embossed to form a plurality of retaining structures (e.g., retaining structures 230), and then exposed to a light source to activate a curing reaction in the material to create the cured structured graphical icon layer 220.

[0025] As noted elsewhere in this disclosure, dimensions along which the performance of a micro-optical security device can be measured include, but are not limited to, the degree to which the device and the optical effects it produces are visually attention-grabbing. If a micro-optical security device truly "grabs the viewer's attention," then its absence or something unusual about its appearance is more likely to be noticed by a user. Aesthetics grab people's attention, and from an anti-counterfeiting perspective, attention can be very advantageous.

[0026] Experience has shown that clarity and the presence of multiple colors can provide additional attention in visual effects (e.g., composite images) presented by micro-optical systems. In many cases, micro-optical security devices are more likely to provide a clear visual effect when the image icon has an appropriate thickness and is located within the focal plane of the light collecting elements of the planar array of light collecting elements. According to some embodiments, suitable image icon thicknesses include thicknesses in the range between 0.5 μm and 3.5 μm. In some embodiments, suitable image icon thicknesses include narrower ranges of thicknesses, such as 0.5-2.5 μm or 1.5-1.8 μm. In some applications, suitable image icons have thicknesses greater than 3.5 μm or less than 0.5 μm. With "faint" or out-of-focus icons, including but not limited to, the color(s) of the composite image may appear washed out and image details may appear blurred. Additionally, image icons that are two or more contrasting colors within the image icon layer can provide visual attention with micro-optical security devices. However, the implementation of multi-colored image icons may pose technical challenges. One way to implement multiple colors is to overlay a first image icon layer containing image icons of a first color on top of a second image icon layer containing image icons of a second color. However, this approach presents a number of technical challenges, including controlling the alignment of the first image icon layer relative to the second image icon layer and the possibility that one or both of the overlaid image icon layers may be out of the focal plane of the light collection element. Furthermore, when the system is configured to present a composite image, errors in the alignment of the image icon layer relative to the light collection element may result in "jumps" or discontinuities in the dynamic appearance of the composite image. For example, in a composite image that includes an object that rotates and changes color when viewed in a range of colors, variations in alignment between the two image icon layers relative to the light collection layer may result in abrupt or non-continuous transitions between colors and in the appearance of rotation.As an illustrative example, consider a dynamic visual effect including a composite image of a multi-colored ball moving through a first position, a second position, a third position, and a fourth position in response to a change in viewing angle. If the phase of the elements of the image icon layer is not tightly controlled relative to the phase of the focusing elements, a "jump" between the positions of the ball, i.e., a non-continuous transition, may occur. In the example situation of the composite image of a ball, when the ball appears in the composite image in response to a change in viewing angle, the phase error may cause the ball to "jump" from the first position to the third position, skipping the second position. Another approach to implementing multiple colors is to mechanically isolate areas of uncured colorant material of a first color at specific locations in a structured image icon layer, blade off the excess colorant material of the first color, flood cure the image icon layer (e.g., non-selectively expose the entire surface of the image icon layer), and repeat the process for one or more additional colors. Technical challenges associated with repeatedly applying areas of one color, smoothing excess from the device with a blade, and then flood curing the device include, for example, smearing and staining associated with an amount of a first color colorant material occupying locations in the image icon layer intended for a second color colorant material and curing it by flood curing prior to the introduction of the second color material. The presence of cured first color material in spaces intended for the second color material can result in muddy transitions between colors or unwanted color inclusions.

[0027] Advantageously, certain embodiments according to the present disclosure include graphical icons formed from photocurable colored materials of two or more contrasting colors (e.g., two different primary colors, such as red and green, or different shades of the same base color, such as black and gray). Moreover, certain embodiments according to the present disclosure advantageously avoid the technical challenges associated with attempting to achieve multiple colors by stacking graphical icon layers of different colors, or repeatedly attempting to mechanically separate regions of different color ink, remove excess ink, and flood cure the device. Instead, visual effects (e.g., composite images) produced by micro-optical security devices according to certain embodiments of the present disclosure exhibit sharp transitions between zones of different colors and enhanced color saturation associated with positioning the graphical icon within a single graphical icon layer, providing greater certainty that the graphical icon is within the focal plane of the light-collecting elements of a planar array of light-collecting elements. Furthermore, by achieving sharp transitions between zones of a first color image icon and zones of a second color image icon within a single image icon layer, the repeating phase of the image icon layer pattern relative to the repeating pattern of the focusing elements (e.g., a grid or hexagonal lattice) can be tightly controlled, avoiding "jumps" or abrupt changes in the visual effect produced by the micro-optical security device across changing viewing angles.

[0028] As shown in the illustrative example of FIG. 2, within the holding structures of the image icon layer 220 there is a first zone of image icons (e.g., first image icon 240) having a subset of holding structures that include a first color of hardened colorant material, and a second zone of image icons (e.g., second image icon 245) having a subset of holding structures that include a second color of hardened colorant material.

[0029] Figures 3A-3F illustrate aspects of the structure and manufacture of a section 300 of a structured image icon layer in accordance with various embodiments of the present disclosure. For convenience, structures common to one or more of Figures 3A-3F are similarly numbered.

[0030] Referring to the non-limiting example of FIG. 3A, a section 300 of a structured graphical icon layer is shown. According to various embodiments, section 300 includes a plurality of retaining structures (e.g., retaining structure 301) that define isolated volumes. In this non-limiting example, as shown in FIG. 3A, each of the retaining structures of section 300 of the structured graphical layer includes a square well of a first depth d. According to various embodiments, the shape and depth of the retaining structures within section 300 may vary. Additionally, in some embodiments, section 300 of the icon layer may include unstructured regions, i.e., regions where graphical icons may be formed by other methods.

[0031] In this illustrative example, a first zone of the graphical icon is shown as a square region 310 defining a subset of the retaining structure that includes a volume of hardened colorant material of a first color.

[0032] FIG. 3B illustrates operations in forming a zone-cured graphical icon layer according to certain embodiments of the present disclosure. As shown in the non-limiting example of FIG. 3, a layer 315 of uncured pigmented material (e.g., UV-reactive ink) of a first color is applied to a portion of section 300 of the structured graphical layer, including region 310. According to some embodiments, layer 315 may be applied in a manner that attempts to limit application of ink to the support structures outside region 310 (e.g., by using chablon or lithographic techniques). As shown in the illustrative example of FIG. 3B, in some embodiments, despite efforts to mechanically remove ink from the support structures outside region 310, some of the pigmented material (e.g., excess ink 317) may occupy the support structures outside the region including the first zone of the graphical icon. As described elsewhere in this disclosure, by curing the uncured pigmented material according to some embodiments of the present disclosure by zone, this overflow, i.e., excess uncured pigment, does not degrade the overall performance of the micro-optical device. Thus, in some implementations of the present disclosure, the first colored pigmented material is applied throughout section 300.

[0033] FIG. 3C illustrates the operations in forming a zone-cured graphical icon layer according to various embodiments of the present disclosure. Referring to the non-limiting example of FIG. 3C, a structured graphical icon layer including section 300 is scraped (e.g., by doctoring the surface) such that the uncured color material of the first color remains primarily or exclusively on the support structures of the graphical icon layer at a depth equal to or less than the first depth d. As shown in the present disclosure, in some embodiments, certain support structures outside of region 310 will have the color material (e.g., 317) of the first region 310. However, it has been found that advantages of certain embodiments according to the present disclosure include the fact that the presence of uncured color material outside of the designated regions prior to curing does not diminish the ability to produce a micro-optical security device that provides visual effects that attract the user's attention, including sharp transitions between color regions, or between distinct and easily understood color regions.

[0034] FIG. 3D illustrates operations in forming a zone-cured graphical icon layer according to various embodiments of the present disclosure. In certain embodiments according to the present disclosure, an area of ​​a first region 310 is selectively, i.e., zone-wise, cured with patterned light 320 of a frequency or wavelength suitable for curing a first color coloring material in the support structures of the structured graphical icon layer to generate a graphical icon of a first zone in the region 310. According to certain embodiments, areas outside the region 310 of the section 300 are not zone-cured, and the first color coloring material remains substantially, if not completely cured. According to various embodiments, the patterned light 320 projected onto the region 310 is provided by rendering a UV projector with UV light pixels of a digital image (e.g., a mask file). In some embodiments, the patterned light 320 is projected by a rastering UV laser. In some embodiments according to the present disclosure, the patterned light 320 is projected directly onto the surface of the structured graphical icon layer including the section 320. In certain embodiments, the patterned light 320 is projected through a focusing element of a micro-optical security device including the section 300 (e.g., a planar array of focusing elements 107 of FIG. 1). According to various embodiments, the directionality of the visual effect provided by the micro-optical device (e.g., the viewing angle at which the visual effect is perceptible) can be controlled by zone-wise curing of the colored material through the focusing element. Furthermore, in certain embodiments, the patterned light 320 can be projected both through the focusing element and directly onto the structured image icon layer to generate variations in the visual effect provided by the strip within the security device. In certain embodiments, the pattern underlying the patterned light 320 can be dynamically, i.e., repeatedly, changed during the manufacturing process. For example, in some embodiments, the pattern underlying the patterned light 320 corresponds to a serial number or batch number of a banknote, thereby enhancing counterfeit resistance by making each micro-optical security device unique to a particular document.

[0035] FIG. 3E illustrates operations in forming a zone-cured graphical icon layer according to various embodiments of the present disclosure. According to certain embodiments, all or nearly all of the uncured material of the first color is removed in areas outside of region 310, leaving only the graphical icon of the first zone of the first color graphical icon. In certain embodiments, the uncured pigment of the material is removed using a mild solvent spray wash to completely or substantially remove the first color colored material (cured or uncured) in the retaining structure outside of region 310. In some embodiments, selectively or zone-curing the first color colored material substantially reduces the occurrence of color smearing or color blending of the graphical icon in the retaining structure of the graphical icon layer. Advantageously, this aids in the manufacture of micro-optical security devices that support visual effects characterized by sharp transitions between different colored areas and clean colored areas.

[0036] FIG. 3F illustrates operations in forming a zone-hardened pictorial icon layer according to various embodiments of the present disclosure. In certain embodiments, the operations described with reference to FIGS. 3A-3F can be performed again with one or more additional colors of colorant material, including second, third, fourth, and additional colors. Referring to the non-limiting example of FIG. 3F, the operations described with reference to FIGS. 3A-3F are performed again to create a pictorial icon in a first zone of pictorial icons 350 and a second zone of pictorial icons 360. In some embodiments, such as those in which the security device design specifies that all of the retaining structures of the pictorial icon layer be filled with hardened colorant material, the final curing step can be performed using flood curing rather than zone-hardening.

[0037] FIG. 4 illustrates aspects of a device for zone-wise curing of areas of uncured pigmented material, according to various embodiments of the present disclosure.

[0038] Often, micro-optical security devices and security documents incorporating same are constructed using a roll-to-roll manufacturing process in which a web of material is unwound from a first roll, mechanically and physically processed as it passes through one or more machines, and wound onto a second roll. Advantageously, the pictorial icon layer (e.g., the pictorial icon layer comprising section 300 of FIG. 3A) can be zone-wise colored and cured as part of the roll-to-roll manufacturing process for producing the security strip.

[0039] 4, there is shown elements of an apparatus 400 for zone-by-zone curing of a micro-optical image icon layer. According to a particular embodiment, the apparatus 400 includes a projector 401, a positioning roller 410, and a position sensor 420.

[0040] In some embodiments, the projector 401 is configured to project a pattern of light 415 as the moving web 430 passes from the positioning roller 410 to a cleaning station or other process configured to remove uncured colorant material. According to certain embodiments, the projector 401 comprises a UV raster laser, a video projector, or other device capable of projecting a dynamic (e.g., moving in synchrony with the moving web 430) pattern of light of a wavelength suitable for curing portions of the layer of uncured colorant material on the moving web 430. As shown in the illustrative example of FIG. 4, the moving web 430 coated with a layer of uncured colorant material of a first color passes over the positioning roller 410 and enters the projection zone of the projector 401. According to various embodiments, the positioning roller 410 operates to maintain a predetermined level of tension and flatness in the moving web 430 as it enters the projection zone of the projector 401.

[0041] Referring to the non-limiting example of FIG. 4, position sensor 420 tracks the speed and current position of a reference point (e.g., a score mark or other position indicator) in moving web 430 relative to projector 401 and provides the position data to a computer or other control device for projector 401.

[0042] According to various embodiments, the projector 401 is configured to project a pattern of curing light corresponding to a zone of the first color image icon onto the moving web 430 as the moving web 430 passes through the projection zone of the projector 401. In certain embodiments, since the moving web 430 is constantly moving, to achieve the benefit of zone-by-zone curing, the pattern of light 415 projected by the projector moves in synchrony with the moving web 430 such that the same or approximately the same area of ​​the layer of uncured colored material is exposed as the moving web 430 passes through the projection zone of the projector 401. Similarly, the pattern of light 415 is projected onto the moving web 430 such that the same or approximately the same area of ​​the layer of uncured colored material is not exposed as the moving web 430 passes through the projection zone of the projector 401. Multiple instances of the apparatus 400 can be incorporated as part of a roll-to-roll manufacturing system for micro-optical security devices according to embodiments of the present disclosure. In certain embodiments, a layer of uncured colorant material of a first color is applied and cured zone by zone, and the uncured material is washed away in preparation for repeating the process with a layer of uncured colorant material of a second color.

[0043] FIG. 5 illustrates operations of a method 500 for manufacturing a zone-hardened micro-optical security device according to various embodiments of the present disclosure.

[0044] Referring to the non-limiting example of Figure 5, a layer of uncured pigmented material of a first color (e.g., layer 315 of Figure 3) is applied to a graphical icon layer (e.g., graphical icon layer 220 of Figure 2) of a micro-optical security device (e.g., micro-optical security device 100 of Figure 1) in operation 505. As discussed elsewhere in this disclosure, the graphical icon layer can be part of a micro-optical security device that employs refractive (e.g., an array of microlenses) or reflective (e.g., an array of curved micromirrors) light focusing elements.

[0045] According to certain embodiments, the graphical icon layer to which the layer of uncured colorant material is applied in operation 505 includes a plurality of retaining structures (e.g., retaining structures 230 of FIG. 2) that define isolated volumes having a first depth. In some embodiments, the layer of uncured colorant material fills to the first depth (e.g., to the "top" of the retaining structures). In some embodiments, the applied layer fills all of the retaining structures of the graphical icon layer. In certain embodiments, the layer of uncured colorant material of the first color is selectively applied, for example, using chablon or one or more printing techniques (e.g., inkjet, offset, flexo, split fountain, or screen printing techniques), such that the uncured colorant material is applied to some areas of the graphical icon layer but not to other areas.

[0046] As shown in the illustrative example of FIG. 5, in operation 510, the image icon layer is scraped off such that the uncured colorant material of the first color remains in the retaining structures at a depth equal to or less than the first depth. For example, as shown in FIG. 3C of the present disclosure, excess colorant material on top of the image icon layer is removed and the ink remains in the retaining structures. According to various embodiments, the scraping off of the image icon layer in operation 510 is performed using a doctor blade. In some embodiments according to the present disclosure, one or more solutions (e.g., an oxygen inhibitor solution) are applied to the flat portions, i.e., gap areas between the retaining structures, to prevent curing of the colorant material in these areas so that it can be washed away.

[0047] 5, in operation 515, uncured colorant material of a first color is selectively cured by directing a first pattern of light at a first zone (e.g., region 310 of FIG. 3A) to form a graphical icon of a first array of graphical icons. According to certain embodiments, the graphical icons formed in operation 510 include volumes of cured colorant material of the first color at locations defined by retaining structures of the graphical icon layer.

[0048] In some embodiments, the selective curing performed in operation 510 is performed as part of a roll-to-roll manufacturing process, and a projector (e.g., projector 401 in FIG. 4) is configured to project a pattern of light synchronized with the movement of a moving web that includes the image icon layer. In certain embodiments, a moving physical mask synchronized with the movement of the moving web is used to selectively expose zones in the image icon layer to the curing light. According to various embodiments, the selective, or zone-by-zone, curing performed in operation 510 is performed by projecting the curing light directly onto the image icon layer. In certain embodiments, in operation 510, the curing light is projected indirectly onto the image icon layer (e.g., through a planar array of focusing elements of a micro-optical security device).

[0049] As shown in the illustrative example of Figure 5, in operation 520, uncured pigmented material of a first color is removed from the graphical icon layer. In one exemplary embodiment, operation 520 is performed by passing the graphical icon layer through a spray station where a mild solvent is used to wash the uncured pigmented material from the retaining structures of the structured graphical icon layer.

[0050] Figures 6A-6E illustrate aspects of the structure and manufacture of a section 600 of a micro-optical security device according to various embodiments of the present disclosure. For convenience and ease of reference, elements of section 600 that are recognizable in more than one of Figures 6A-6E are similarly numbered.

[0051] Referring to the non-limiting example of FIG. 6A, a top view of a section of a micro-optical security device (e.g., device 100 of FIG. 1) according to certain embodiments of the present disclosure is shown. In this illustrative example, focusing elements 601 of an array of focusing elements (e.g., planar array of focusing elements 105 of FIG. 1). According to various embodiments, the focusing elements of the planar array of focusing elements 601 include lenses whose centers are approximately aligned with the points of a planar hexagonal lattice. In some embodiments according to the present disclosure, the focusing elements 601 include reflective focusing elements and are arranged according to different patterns (e.g., a square or rectangular lattice). Furthermore, in embodiments where the focusing elements 601 are refractive focusing elements, the focusing elements 601 can have variously concave or convex lens surfaces depending on the structure of the micro-optical security device.

[0052] Referring to the non-limiting example of FIG. 6B, a bottom view of a section 600 of a micro-optical security device is shown. In this illustrative example, a pictorial icon layer 605 including a plurality of retaining structures (e.g., retaining structure 607) is visible in this bottom view. As shown in this illustrative example, the retaining structures of the pictorial icon layer 605 are arranged in a planar hexagonal lattice, similar to the focusing elements of the planar array of focusing elements 601. Furthermore, in the non-limiting example of FIG. 6B, the resolution of the planar array of focusing elements 601 is the same or approximately the same as the resolution of the pictorial icon layer 605, with one retaining structure disposed within the footprint of each focusing element. Other embodiments having different geometries of the retaining structures, as well as different relative resolutions of the focusing elements and the retaining structures, are possible and within the intended scope of the present disclosure.

[0053] Referring to the non-limiting example of FIG. 6C, an uncured colorant material 609 of a first color is selectively applied to a portion of the image icon layer 605 to define a first zone of color. According to various embodiments, the uncured colorant material 609 is selectively applied by applying one or more techniques to precisely apply ink to a final substrate (e.g., paper or polymer substrate). Examples of suitable methods for applying the uncured colorant material 609 include, but are not limited to, inkjet printing, offset lithography, direct write lithography, flexography, and varying the composition of the uncured colorant material 609 to adjust parameters related to its ability to wet the image icon layer 605 (e.g., hydrophilicity). According to certain embodiments, the uncured colorant material 609 is applied by overflowing the retaining structure, thereby wetting the interstitial spaces (e.g., interstitial regions 611) and forming one or more clumps of liquid having edges (e.g., edges 613) on the surface of the icon layer. It should also be noted that in certain embodiments according to the present disclosure, one or more volumes (e.g., volume 615) of uncured colorant material 609 may partially fill one or more retaining structures within graphical icon layer 605.

[0054] Referring to the non-limiting example of FIG. 6D, according to certain embodiments, after the uncured coloring material 609 of a first color is selectively applied to the graphical icon layer 605, the uncured coloring material 621 of a second color is applied to the graphical icon layer 605 in an area corresponding to a second zone of color. According to various embodiments, the uncured coloring material 621 is similarly selectively provided in an amount sufficient to not only fill the retaining structures, but also to generate one or more aggregates of fluid that cover the interstitial spaces between the retaining structures (e.g., the interstitial spaces 623) and also meet with one or more aggregates of the uncured coloring material of a different color (e.g., the uncured coloring material 609) along one or more boundaries (e.g., the boundaries 625). According to various embodiments, the retaining structures of the first zone are filled with the uncured coloring material 609 to an appropriate depth (e.g., filling or substantially filling the retaining structures to a depth in the range of 1 μm to 3 μm), so that the uncured coloring material 621 of the second color is not drawn into the retaining structures of the first zone. Thus, in certain embodiments according to this disclosure, the border 625 occupies approximately the same position on the image icon layer as the edge 613 .

[0055] 6E, in certain embodiments according to the present disclosure, the bulk or excess of the uncured pigment material 609 and the uncured pigment material 621 are removed from the interstitial spaces of the pictorial icon layer 605, leaving the uncured pigment material 609 of the first color substantially in the first zone 630 and the uncured pigment material 621 of the second color substantially in the second zone 635. Although one or more of the retaining structures around the boundary between the first zone 630 and the second zone 635 may contain uncured pigment material of multiple colors, this does not significantly affect the sharpness of the color transition achieved by a micro-optical security device incorporating the pictorial icon layer 605 for at least the following reasons: First, as noted elsewhere in this disclosure, it has been observed that a retaining structure filled or mostly filled with a non-pigmented material of one color does not attract a non-pigmented material of another color that is applied to nearby areas of the pictorial icon layer. Second, and as described with reference to Figure 7 of this disclosure, in some embodiments, the effect of the "out-of-zone" unpigmented material can be mitigated by zonal curing or dilution of the "out-of-zone" material. According to various embodiments, uncured pigmented material 609 and uncured pigmented material 621 are cured to catalyze a chemical reaction that imparts structural stability to the material within the retention structure.

[0056] Advantageously, in certain embodiments, by selectively applying multiple colors of uncured colorant material to fill substantially all of the support structures of the graphical icon layer, removing any excess, and curing multiple zones of color together, a much sharper color transition is achieved than can be achieved by repeatedly applying, blading, and curing each color of uncured colorant material.

[0057] FIG. 7 illustrates a non-limiting set of examples of how certain embodiments according to the present disclosure can achieve sharp color transitions.

[0058] Referring to the non-limiting example of Figure 7, a micro-optical device 700 is shown in accordance with certain embodiments of the present disclosure. According to various embodiments, the micro-optical device 700 includes an array of focusing elements 701 (e.g., the array of focusing elements 601 of Figure 6A). In some embodiments, the micro-optical security device 700 further includes an optical spacer 703 (e.g., the optical spacer 110 of Figure 1). Additionally, in some embodiments, the micro-optical device 700 includes a structured graphical icon layer 705 (e.g., the structured graphical icon layer including sections 300 of Figures 3A-3F), which includes a plurality of retention structures including, for example, retention structure 710.

[0059] As discussed elsewhere in this disclosure, reducing, or more preferably substantially eliminating, the occurrence of image icons comprising cured materials of different colors improves the sharpness of the transition observed between a first region of an image icon of a first color and a second region of an image icon of a second color in the visual effect (e.g., a composite image) produced by the micro-optical device.

[0060] Referring to the non-limiting example of FIG. 7, the portion of the image icon layer 705 shown in FIG. 7 includes an area around an intended boundary 711 between a first zone of a first color (labeled “A” in the figure) and a second zone of a second color (labeled “B” in the figure).

[0061] According to various embodiments, a first color of uncured colorant material 715 (shown with diagonal shading) is selectively applied to the graphical icon layer. As shown in this illustrative example, the uncured colorant material 715 is selectively applied to primarily fill the retaining structures of a first zone "A", although in some embodiments, a portion of the uncured colorant material 715 (also referred to herein as an "out-zone" color) is present in the retaining structures of a second zone "B" (e.g., retaining structure 720).

[0062] In embodiments using zone-by-zone curing, the impact of out-of-zone color from uncured color material 715 on the performance of the micro-optical system can be minimized by curing the graphical icon layer 705 in zones such that only the support structures in zone "A" are cured and the out-of-zone uncured color material 715 in zone "B" can be washed away before applying a second color of uncured color material 725 (shown in the figure with cross-hatching).

[0063] Similarly, in certain embodiments in which substantially all of the retaining structures of the graphical icon layer are filled with uncured colorant material of two or more colors (e.g., those described with reference to Figures 6A-6E), the impact of out-of-zone uncured colorant material 715 in zone "B" on the appearance of the image produced by the micro-optical security device is similarly mitigated. According to certain embodiments, when uncured colorant material 725 of a second color is introduced to a retaining structure (e.g., retaining structure 720) containing out-of-zone uncured colorant material 715 of a first color, these uncured colorant materials may mix prior to curing, avoiding performance issues associated with having pockets or volumes of two or more different colors of cured material at the "bottom" (i.e., the portion of the retaining structure closest to the focusing element of the micro-optical device).

[0064] In certain embodiments, a second color of uncured color material 725 is selectively applied to the graphical icon layer 705, targeting the retaining structures in a second zone "B" of the graphical icon layer 705. In certain embodiments, an amount of uncured color material 725 passes out of the zone into the retaining structures in zone "A" (e.g., retaining structure 710). Advantageously, in certain embodiments according to the present disclosure, the uncured color material 725 outside of the zone has been found to not affect the ability to achieve a sharp color transition in the visual effect produced by the micro-optical system 700.

[0065] For example, in some embodiments where the first color uncured color material 715 is cured in zones prior to application of the uncured color material 725, the first color material occupies the "bottom" of the holding structure, avoiding the possibility of the cured color material being present in the portion of the image icon layer closest to the light collection elements. Similarly, in some embodiments, the second color uncured color material 725 is cured in zones, allowing much, if not all, of the out-of-zone uncured color material 725 to be washed away. In various embodiments, the second color uncured color material 725 is flood cured. However, the presence of the first color cured material confines the second color out-of-zone uncured material 725 to the portion of the holding structure furthest from the light collection elements, where its presence is less noticeable in the visual effect produced by the micro-optical security device 700.

[0066] As a further example, in certain embodiments according to the present disclosure where a first color of uncured color material 715 is first selectively applied to a target retention structure in zone "A", it has been observed that retention structures that are filled or nearly filled with uncured color material 715 generally do not attract a second color of uncured color material 725 due to hydrostatic pressure effects. Furthermore, when uncured color materials of different colors are present in a retention structure, the uncured color materials can mix, avoiding problems associated with having cured color materials of different colors at the "bottom" of the retention structure.

[0067] An example of a micro-optical security device according to various embodiments of the present disclosure includes a micro-optical security device comprising: a planar array of focusing elements; a pictorial icon layer including a plurality of retaining structures defining an isolated volume of a first depth within the pictorial icon layer; a first zone of the pictorial icon including a first predetermined subset of the plurality of retaining structures, the isolated volumes of the retaining structures of the first predetermined subset of the plurality of retaining structures comprising a hardened colored material of a first color; and a second zone of the pictorial icon including a second predetermined subset of the plurality of retaining structures, the isolated volumes of the retaining structures of the second predetermined subset of the plurality of retaining structures comprising a hardened colored material of a second color, the second color contrasting with the first color.

[0068] An example of a micro-optical security device according to various embodiments of the present disclosure includes a micro-optical security device in which a depth of a first color of hardened color material in a first zone of a graphical icon is less than a first depth and a depth of a second color of hardened color material in a second zone of the graphical icon is greater than or equal to the first depth.

[0069] An example of a micro-optical security device according to various embodiments of the present disclosure includes a micro-optical security device in which a first predetermined subset of a plurality of retaining structures corresponds to a dynamically customized display provided by the micro-optical security device.

[0070] An example of a micro-optical security device according to various embodiments of the present disclosure includes a micro-optical security device in which a dynamically customized display provided by the micro-optical security device includes a unique alphanumeric identifier of the micro-optical security device.

[0071] An example of a micro-optical security device according to various embodiments of the present disclosure includes a micro-optical security device in which a dynamically customized display includes a graphic icon from a first zone of graphic icons and a second zone of graphic icons.

[0072] An example of a micro-optical security device according to various embodiments of the present disclosure includes a micro-optical security device in which an image icon of a first zone of image icons and an image icon of a second zone of image icons occupy positions in an image icon layer associated with a common phase relationship relative to the focusing elements of the planar array of focusing elements, and when viewed through the focusing elements of the planar array of focusing elements, the image icon of the first zone of image icons and the image icon of the second zone of image icons exhibit a dynamic visual effect that changes in appearance over a range of viewing angles, and the common phase relationship of the first zone and second zone of image icons relative to the focusing elements of the planar array of focusing elements produces a continuous change in appearance of the dynamic visual effect.

[0073] An example of a micro-optical security device according to various embodiments of the present disclosure includes a micro-optical security device in which the colorant material of a first color is removed from a second zone of the graphical icon.

[0074] An example of a micro-optical security device according to various embodiments of the present disclosure includes a micro-optical security device further comprising a layer of hardened colorant material disposed at a depth equal to or greater than the first depth and aligned with at least a portion of the plurality of retention structures.

[0075] An example of a micro-optical security device according to various embodiments of the present disclosure includes a micro-optical security device in which the focusing elements of the planar array of focusing elements are refractive focusing elements and the image icon layer is disposed adjacent to a focal plane of the planar array of focusing elements.

[0076] An example of a micro-optical security device according to various embodiments of the present disclosure includes a micro-optical security device in which the focusing elements of the planar array of focusing elements are reflective focusing elements and the image icon layer is disposed proximate to a focal plane of the planar array of focusing elements.

[0077] An example of a micro-optical security device according to various embodiments of the present disclosure includes a micro-optical security device in which each focusing element of a planar array of focusing elements has a footprint, and a first zone of a graphical icon corresponds to a portion of the footprint of a first subset of focusing elements in which the first zone of the graphical icon is visible over a predetermined range of viewing angles.

[0078] An example of a micro-optical security device according to various embodiments of the present disclosure includes a micro-optical security device including a photocurable ink in which a curable colorant material of a first color polymerizes in response to light wavelengths in the emission spectrum of a light emitting diode (LED) lamp.

[0079] An example of a micro-optical security device according to various embodiments of the present disclosure includes a micro-optical security device further comprising a third zone of a pictorial icon comprising a third predetermined subset of the plurality of retaining structures, wherein a separated volume of the retaining structures of the first predetermined subset of the plurality of retaining structures comprises hardened colored material of a third color, the third color contrasting with the first color and the second color.

[0080] An example of a micro-optical security device according to various embodiments of the present disclosure includes a micro-optical security device in which one or more image icons of a first zone of image icons are positioned proximate to one or more image icons of a second zone of image icons such that, when viewed through the focusing elements of a planar array of focusing elements, one or more image icons of the first zone of image icons proximate to one or more image icons of the second zone of image icons appear as areas of a third color, the third color being a mixture of the first color and the second color.

[0081] An example method of making a micro-optical security device according to various embodiments of the present disclosure includes applying a layer of uncured colorant material of a first color to a graphical icon layer of a micro-optical security device, the graphical icon layer including a plurality of retaining structures defining isolated volumes of a first depth within the graphical icon layer; scraping the graphical icon layer such that the uncured colorant material of the first color remains in the retaining structures of the graphical icon layer at a depth equal to or less than the first depth; selectively curing the layer of uncured colorant material of the first color by directing a first pattern of light at a first zone of the graphical icon layer to form a first array of graphical icons; and removing the uncured colorant material of the first color.

[0082] An example method for making a micro-optical security device according to various embodiments of the present disclosure includes scraping the image icon layer with a doctor blade.

[0083] An example of a method for making a micro-optical security device according to various embodiments of the present disclosure includes removing the uncured pigmented material with a spray wash.

[0084] An example method for making a micro-optical security device according to various embodiments of the present disclosure includes a method further comprising selectively curing the first color of uncured pigmented material using rasterized projection from a DLP UV projector, an LED projector, or a UV laser.

[0085] An example method of making a micro-optical security device according to various embodiments of the present disclosure includes a method further comprising applying a layer of uncured pigmented material of a second color that contrasts with the first color to a graphical icon layer of the micro-optical security device, scraping off the graphical icon layer, and curing the uncured pigmented material of the second color.

[0086] An example method of making a micro-optical security device according to various embodiments of the present disclosure includes a method further comprising flood curing said layer of uncured pigmented material of a second color.

[0087] An example method for making a micro-optical security device according to various embodiments of the present disclosure includes a method further comprising selectively curing the layer of uncured pigmented material of a second color by directing a second pattern of light at a second zone of the pictorial icon layer to form a second array of pictorial icons, and removing the uncured pigmented material of the second color.

[0088] An example method for making a micro-optical security device according to various embodiments of the present disclosure includes a method further comprising applying a layer of uncured colorant material of a third color that contrasts with the first and second colors to the graphical icon layer, and curing the layer of uncured colorant material of the third color.

[0089] An example method for making a micro-optical security device according to various embodiments of the present disclosure includes directing a first pattern of light directly onto the graphical icon layer.

[0090] An example method of making a micro-optical security device according to various embodiments of the present disclosure includes selectively applying a first amount of uncured pigment material of a first color to a first region of a pictorial icon layer of the micro-optical security device, the pictorial icon layer including a plurality of retaining structures defining isolated volumes of a first depth within the pictorial icon layer, and selectively applying a second amount of uncured pigment material of a second color to a second region of the pictorial icon layer of the micro-optical security device, at least a portion of the second region being adjacent at least one of the first region along a wetted boundary of a surface of the pictorial icon layer. selectively applying a second amount of uncured colorant material of a second color to contact a portion of the first zone of the graphical icon layer; scraping the graphical icon layer such that the uncured colorant material of the first color is substantially confined to the retaining structure of the first zone of the graphical icon layer and the uncured colorant material of the second color is substantially confined to the retaining structure of the second zone of the graphical icon layer; and curing the uncured colorant material of the first color and the uncured colorant material of the second color, wherein the first zone of the graphical icon layer and the second zone of the graphical icon layer abut along an area of ​​the graphical icon layer proximate the location of the wet boundary.

[0091] An example method for making a micro-optical security device according to various embodiments of the present disclosure includes scraping the image icon layer with a doctor blade.

[0092] An example method for making a micro-optical security device according to various embodiments of the present disclosure includes flood curing the graphical icon layer.

[0093] An example method for making a micro-optical security device according to various embodiments of the present disclosure includes zone-wise curing of one or more of the first zone of the graphical icon layer or the second zone of the graphical icon layer.

[0094] Examples of methods for making micro-optical security devices according to various embodiments of the present disclosure include selectively applying a first color of uncured pigmented material using one or more of inkjet printing, intaglio printing, chablon, offset lithography, direct-draw lithography, or flexography.

[0095] An example method of making a micro-optical security device according to various embodiments of the present disclosure includes a method including selectively applying a third amount of uncured colorant material to a third region of the graphical icon layer, the third color contrasting with the first color and the second color; scraping the graphical icon layer such that the uncured colorant material of the first color is substantially confined to a retaining structure of the first zone of the graphical icon layer, the uncured colorant material of the second color is substantially confined to a retaining structure of the second zone of the graphical icon layer, and the uncured material of the third color is substantially confined to a retaining structure of the third zone of the graphical icon layer; and curing the uncured colorant material of the first color, the uncured colorant material of the second color, and the uncured colorant material of the third color.

[0096] An example method for making a micro-optical security device according to various embodiments of the present disclosure includes indirectly directing a first pattern of light through one or more lens surfaces of a planar array of light focusing elements onto a graphical icon layer.

[0097] Nothing in this application should be construed as implying that a particular element, step, or function is an essential element required for inclusion in a claim. Patent subject matter is defined solely by the claims. Moreover, no claim is intended to invoke 35 U.S.C. 112(f) unless the phrase "means for" is followed by a participle.

Claims

1. A micro-optical security device (100) having zone-by-zone color transitions, comprising: a planar array of focusing elements (140); a pictorial icon layer (120) including a plurality of holding structures (710), the plurality of holding structures (710) defining isolated volumes of a first depth within the pictorial icon layer; a first zone (350) of graphical icons, the first zone (350) including a first plurality of graphical icons belonging to a first predetermined subset of the plurality of holding structures, the separated volumes of holding structures of the first predetermined subset of the plurality of holding structures including a first colored pigmented material, the first colored pigmented material being photocurable and cured by light; a second zone (360) of pictorial icons, the second zone (360) including a second plurality of pictorial icons belonging to a second predetermined subset of the plurality of holding structures, the separated volumes of holding structures of the second predetermined subset of the plurality of holding structures including a second colored material, the second color being a photocurable colored material that is hardened by light, the second color being contrasting with the first color; A micro-optical security device comprising:

2. a depth of the hardened color material of the first color in a first zone of the graphical icon is less than the first depth; a depth of the hardened color material of the second color in a second zone of the graphical icon is equal to or greater than the first depth; The micro-optical security device of claim 1 .

3. The micro-optical security device of claim 1 , wherein said first predetermined subset of said plurality of retention structures corresponds to a dynamically customized display provided by said micro-optical security device.

4. The micro-optical security device of claim 3 , wherein the dynamically customized display provided by the micro-optical security device includes a unique alphanumeric identifier for the micro-optical security device.

5. The micro optical security device of claim 3 , wherein said dynamically customized display includes image icons from said first zone of image icons and said second zone of image icons.

6. The micro-optical security device of claim 1 , wherein a second zone of said pictorial icon is free of said first colored colorant.

7. The micro-optical security device of claim 1 further comprising a layer of hardened pigmented material disposed at a depth equal to or greater than said first depth and aligned with at least a portion of said plurality of retention structures.

8. the focusing elements of the planar array of focusing elements are refractive focusing elements; the graphical icon layer is disposed proximate a focal plane of the planar array of light collecting elements; The micro-optical security device of claim 1 .

9. the concentrating elements of the planar array of concentrating elements are reflective concentrating elements; the graphical icon layer is disposed proximate a focal plane of the planar array of light collecting elements; The micro-optical security device of claim 1 .

10. each concentrating element of the planar array of concentrating elements has a footprint; a first zone of the graphical icon corresponds to a portion of a footprint of a first subset of concentrating elements in which the first zone of the graphical icon is visible over a predetermined viewing angle range; The micro-optical security device of claim 1 .

11. 10. The micro-optical security device of claim 1, wherein the cured color material of the first color comprises a photocurable ink that polymerizes in response to light wavelengths in the emission spectrum of a light emitting diode (LED) lamp.

12. 2. The micro-optical security device of claim 1, further comprising a third zone of a pictorial icon comprising a third predetermined subset of the plurality of retaining structures, the separated volumes of the retaining structures of the first predetermined subset of the plurality of retaining structures comprising hardened colored material of a third color, the third color contrasting with the first color and the second color.

13. one or more image icons of a first zone of image icons are positioned proximate to one or more image icons of a second zone of image icons such that, when viewed through a focusing element of the planar array of focusing elements, one or more image icons of the first zone of image icons proximate to one or more image icons of the second zone of image icons appear as areas of a third color; the third color being a mixture of the first color and the second color; The micro-optical security device of claim 1 .

14. the image icon of the first zone of image icons and the image icon of the second zone of image icons occupy positions in a layer of image icons associated with a common phase relationship with respect to the focusing elements of the planar array of focusing elements; when viewed through a focusing element of the planar array of focusing elements, the image icon of the first zone of image icons and the image icon of the second zone of image icons exhibit a dynamic visual effect that changes appearance over a range of viewing angles; the common phase relationship of the first and second zones of the graphical icon to the focusing elements of the planar array of focusing elements produces a continuous change in the appearance of the dynamic visual effect. The micro-optical security device of claim 1 .

15. 1. A method of making a micro-optical security device, comprising: applying a layer of uncured pigmented material of a first color to a pictorial icon layer (120) of a micro-optical security device (100), the pictorial icon layer including a plurality of retention structures (710) defining isolated volumes of a first depth within the pictorial icon layer; scraping the graphical icon layer such that uncured colorant material of the first color remains on the retention structure of the graphical icon layer at a depth less than or equal to the first depth; selectively curing the layer of uncured pigmented material of a first color by directing a first pattern of light onto first zones of the graphical icon layer to form a first array of graphical icons (350); removing uncured pigment material of the first color; The method comprising:

16. The image icon layer is scraped off with a doctor blade, removing said uncured pigmented material by spray washing; or directing the first pattern of light directly onto the graphical icon layer; The method of claim 15.

17. 16. The method of claim 15, further comprising selectively curing the first color of uncured pigmented material using rasterized projection from a DLP UV projector, an LED projector, or a UV laser.

18. applying a layer of uncured pigmented material of a second color that contrasts with the first color to the pictorial icon layer of the micro-optical security device; scraping off the image icon layer; curing the uncured colorant material of the second color; and 16. The method of claim 15, further comprising:

19. flood curing the layer of uncured colorant material of the second color; or selectively curing the layer of uncured colorant material of the second color by directing a second pattern of light onto second zones of the graphical icon layer to form a second array of graphical icons; removing uncured colorant material of the second color; and 20. The method of claim 18, further comprising:

20. applying a layer of uncured colorant material of a third color contrasting with the first color and the second color to the graphical icon layer; curing the layer of uncured colorant material of the third color; and 20. The method of claim 19, further comprising:

Images