Micro-optical device with multi-color background icon structure and corresponding manufacturing method

Abstract

A micro-optical device includes an array of focusing elements (105) having a first repetition period along a first axis (201) and a second repetition period along a second axis (203). The micro-optical device also includes an icon layer (120) including a plurality of holding structures, a first plurality of icons in a first region (427) of the plurality of holding structures, and a second plurality of icons formed as regions of solidified photocurable material of a second color disposed on or within holding structures of a second region (429) of the plurality of holding structures. The first plurality of icons has a third repetition period along the first axis and a fourth repetition period along the second axis. The second plurality of icons has a fifth repetition period along the first axis and a sixth repetition period along the second axis.

Description

Technical Field

[0001] This disclosure generally relates to anti-counterfeiting measures for secure and / or high-value documents (such as banknotes, passports, and tickets). More specifically, this disclosure relates to a micro-optical security device with an enhanced multi-color background icon structure and a method for manufacturing the same. Background Technology

[0002] Micro-optical security devices, or devices comprising a microscale array of focusing elements and an arrangement of image icons (e.g., submicroscale colored material regions) located within the focal plane of the focusing elements (which work together to provide one or more unique visual effects (e.g., a synthetic image with a three-dimensional appearance)), have to date proven to be generally effective in providing credible visual markings of authenticity for valuable documents such as banknotes, authentication labels, and passports.

[0003] The performance and effectiveness of micro-optical security devices as a visual marker of document authenticity (i.e., capable of being detected by the human eye rather than by banknote equipment manufacturer (“BEM”) devices or other specialized machinery) depends at least in part on the degree to which the micro-optical security device provides a visually appealing effect to the user, and on the flexibility and ease with which the appearance of the security device, or the visual effect provided by the security device, is updated and modified. For example, synthetic images with dull colors or blurred features (which may occur when the image icon layer is out of focus) are more likely to be overlooked by users, thereby increasing the likelihood of counterfeit banknotes circulating unnoticed.

[0004] Furthermore, the challenges in manufacturing micro-optical security devices include the ability to mass-produce such devices, as certain security documents (especially banknotes) are produced, issued, and recalled in very large batches. Therefore, finding ways to achieve manufacturing efficiency (in terms of both expanding the functionality of existing tools and processes) and prudently using slower, higher-precision manufacturing techniques while maintaining the image quality and visual appearance provided by micro-optical security devices remains a source of technical challenges and opportunities for improvement in the field of micro-optical security devices and their manufacturing methods. Summary of the Invention

[0005] This disclosure relates to a micro-optical security device with an enhanced multi-color background icon structure and a method for manufacturing the same.

[0006] In a first embodiment, a micro-optical device includes a focusing element array having a first repetition period along a first axis and a second repetition period along a second axis. The micro-optical device includes an icon layer comprising: a plurality of retaining structures; a first plurality of icons formed as regions of a first-color curable photocurable material disposed on or within a retaining structure of a first region of the plurality of retaining structures; and a second plurality of icons formed as regions of a second-color curable photocurable material disposed on or within a retaining structure of a second region of the plurality of retaining structures. The first plurality of icons have a third repetition period along the first axis and a fourth repetition period along the second axis. The second plurality of icons have a fifth repetition period along the first axis and a sixth repetition period along the second axis. The first region of the plurality of retaining structures includes a portion of the icon layer separated from the second region of the plurality of retaining structures.

[0007] In a second embodiment, a method of manufacturing a micro-optical device includes: providing a focusing element array having a first repetition period along a first axis and a second repetition period along a second axis; and providing a plurality of holding structures within or near the focal plane of the focusing elements in the focusing element array. The method further includes: forming a first plurality of icons by inking a first region of the plurality of holding structures with an uncured photocurable material of a first color; forming a second plurality of icons by inking a second region of the plurality of holding structures with an uncured photocurable material of a second color; curing the uncured photocurable material of the first color; and curing the uncured photocurable material of the second color. The first plurality of icons have a third repetition period along the first axis and a fourth repetition period along the second axis. The second plurality of icons have a fifth repetition period along the first axis and a sixth repetition period along the second axis. The first region of the plurality of holding structures includes a portion of the icon layer separated from the second region of the plurality of holding structures.

[0008] Other technical features may become readily apparent to those skilled in the art from the following figures, description and claims.

[0009] Before implementing the following specific embodiments, it may be advantageous to define certain words and phrases used throughout this patent document. The term “coupled” and its derivatives refer to any direct or indirect connection between two or more elements, regardless of whether those elements are in physical contact with each other. The terms “comprising” and “including” and their derivatives mean unrestricted inclusion. The term “or” is inclusive, meaning and / or. The phrase “associated with” and its derivatives mean including, being included in, interconnected with, containing, being contained within, connected to or connected with, coupled to or coupled with, able to communicate with, cooperate with, interleaved, juxtaposed, proximate, combined with or combined with, having, possessing the properties of, related to, etc. The functionality associated with any particular controller can be centralized or distributed, whether local or remote. The phrase “at least one of” when used with a list of items means that different combinations of one or more of the listed items may be used, and only one item 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.

[0010] Definitions of several other words and phrases are provided throughout this patent document. Those skilled in the art will understand that, in many (if not most) cases, such definitions apply to both the prior and future use of the words and phrases defined in this way. Attached Figure Description

[0011] To more fully understand this disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which: Figure 1 Examples of micro-optical systems according to certain embodiments of the present disclosure are illustrated; Figure 2A and Figure 2B Views illustrating example micro-optical systems embodying a “deep levitation” icon structure according to various embodiments of this disclosure are shown; Figure 3 Examples of micro-optical systems embodying a “deep levitation” icon structure according to various embodiments of this disclosure are illustrated; Figure 4 Examples are illustrated from the following test: scraping an over-inked retaining structure to achieve a clean edge transition between contrasting icon material areas; and Figure 5 The operation of a method for manufacturing a micro-optical safety device according to various embodiments of the present disclosure is illustrated. Detailed Implementation

[0012] The following discussion Figures 1 to 5The various embodiments described in this patent document to illustrate the principles of this disclosure are merely illustrative and should not be construed in any way as limiting the scope of this disclosure.

[0013] Figure 1 Examples of micro-optical systems 100 according to certain embodiments of the present disclosure are illustrated.

[0014] refer to Figure 1 As a non-limiting example, the micro-optical system 100 includes, at a basic level, a planar array 105 of focusing elements (including, for example, focusing element 107) and an image icon arrangement 120 (including, for example, image icons 121). According to various embodiments, each focusing element in the planar array 105 has a coverage area in which one or more image icons from the image icon arrangement 120 are positioned. In some embodiments, the position of the image icons within the image icon arrangement 120 within the respective coverage area of ​​each focusing element corresponds to the space between holding structures in the image icon layer. According to some embodiments, the resolution of the planar array 105 of focusing elements (e.g., the number of focusing elements provided in a specified area such as a 1×1 mm frame) is in a ratio of 1 or greater to the resolution of the image icon arrangement 120 (e.g., the number of focusing elements provided in a specified area). As a non-limiting example, each image icon within the image icon arrangement 120 may fall within the coverage areas of multiple focusing elements. As a further non-limiting example, there may be no image icon within the coverage area of ​​each focusing element within a specified area. Additionally, in some embodiments according to this disclosure, the ratio of the resolution of the planar array 105 of the focusing elements to the resolution of the image icon arrangement 120 may be less than 1. As a non-limiting example, multiple image icons may exist within the coverage area of ​​a particular focusing element. In other words, the zoned cured coloring material area according to embodiments of this disclosure can be at the sub-focusing element scale and the multi-focusing element scale. As used in this disclosure, "uncured coloring material" encompasses polymer inks, coloring polymers, and dye-based inks that change from a wet, uncured state to a harder, drier state in response to a chemical reaction initiated by the application of curing light (e.g., ultraviolet curing light).

[0015] According to certain embodiments, a plurality of focusing elements 105 comprise a planar array of micro-optical focusing elements. In some embodiments, the focusing elements in the planar array 105 of focusing elements include micro-optical refractive focusing elements (e.g., plano-convex or GRIN lenses) having a lens surface that provides a curved interface between regions of different refractive indices (e.g., polymer lens materials and air). In some embodiments, the refractive focusing elements in the planar array 105 of focusing elements are made of a photocurable resin with a refractive index ranging from 1.35 to 1.7 and have a diameter ranging from 5 μm to 200 μm. In various embodiments, the focusing elements in the planar array 105 of focusing elements include reflective focusing elements (e.g., very small concave mirrors) having a diameter ranging from 5 μm to 50 μm. Although the focusing elements in the planar array 105 of focusing elements are shown as comprising circular plano-convex lenses in this exemplary example, other refractive lens geometries (e.g., cylindrical lenses) are also possible and are within the scope of this disclosure.

[0016] like Figure 1 As illustrated in the exemplary example, image icon arrangement 120 includes a set of image icons (including image icon 121) positioned at predetermined locations within the coverage area of ​​the focusing elements in a planar array 105 of focusing elements. According to various embodiments, each image icon in image icon arrangement 120 includes a region of partitioned photocurable material in a space defined by a retaining structure within a structured image icon layer. As used in this disclosure, the term "structured image layer" encompasses a layer of material (e.g., a photocurable resin) that has been embossed or otherwise formed to include structures (e.g., recesses, pillars, grooves, or bosses) for positioning and retaining image icon material. According to certain embodiments, image icon arrangement 120 is configured to facilitate dynamic redesign and reconfiguration of the image icon structure of the micro-optics system 100. For example, in some embodiments, image icon arrangement 120 selectively fills and cures the retaining structure (e.g., with an uncured coloring material of one or more colors) using a photocurable material. Figure 1 As shown, a square well is formed, and the uncured coloring material is then cured to create areas or regions of color within the image icon arrangement 120. In this non-limiting example, different colors within the image icon arrangement 120 are represented by different fill patterns on the surface of the image icons closest to the focus layer. For example, image icon 121 is shown to have the same color as the image icons in its row.

[0017] like Figure 1As illustrated in the exemplary examples, in some embodiments, the micro-optical system 100 includes an optical spacer layer 110. According to various embodiments, the optical spacer layer 110 comprises a film of a substantially transparent material that functions to position image icons in the image icon arrangement 120 within or around the focal plane of the focusing elements in the planar array 105 of focusing elements. In some embodiments according to this disclosure, the optical spacer layer 110 includes a fabrication substrate on which one or more photocurable material layers may be applied, embossed, and light-cured to form a retention structure, which may then be filled or coated with a colored photocurable material and light-cured. As used in this disclosure, the expression "retention structure" encompasses wells, pillars, and other structures on which uncured photocurable colored material may be scraped onto or onto to form image icons. As used in this disclosure, the term "filling," as used in the context of a retention structure filled with image icon layers, encompasses not only filling the entire usable volume of the retention structure with uncured colored material but also filling a majority (e.g., 50% to 80%) of the usable volume of the retention structure with uncured material. In some embodiments, the photocurable material used to form the image icon arrangement 120 is a colorable ultraviolet (UV) curable polymer.

[0018] Since the focusing elements in the plurality of focusing elements 105 are provided in a regular repeating pattern (e.g., a rectangular grid or a diagonal grid), the spatial density of the focusing elements can be described by the repetition period along the measurement axis. As used and with reference to a focusing element in this disclosure, the term "repetition period" encompasses the distance along a given measurement axis on which a predetermined number of iterations of the focusing element pattern are repeated. A lower repetition period value implies a higher density of focusing elements compared to a higher repetition period value. In the case where the focusing elements in the plurality of focusing elements are circular (rather than cylindrical), the value of the repetition period across the vertical axis is generally the same, but is not required to be so. This disclosure contemplates achieving variations in scale ratio by changing the repetition period of the focusing elements or the repetition period of the icon structure.

[0019] Similarly, the spatial density of image icons in image icon arrangement 120 can be described by the repetition period along the measurement axis. As used and referenced in this disclosure, the term "repetition period" encompasses a distance over which a predetermined number of icons are positioned. Similar to focusing elements, a lower repetition period value implies a higher image icon density, while a higher repetition period value implies a lower image icon density.

[0020] The micro-optical system 100 provides visual effects by synthesizing or collectively magnifying the design present in the image icons (or portions thereof) by coordinating the projection of light guided from the icons in the image icon arrangement 120 through the focusing element array 105. The appearance of the visual content projected through the image icons depends on a variety of factors, including but not limited to the local icon-lens scale ratio. As used in this disclosure, the expression "icon-lens scale ratio" encompasses, for a given segment of the micro-optical system 100, the icon repetition period divided by the focusing element repetition period along a given measurement axis. Typical icon-lens scale ratios are slightly higher (e.g., 1.005) or slightly lower (e.g., 0.995) than 1.000. Along the measurement axis that produces stereo parallax (i.e., parallel to the imaginary line separating the observer's eyes), an icon-lens scale ratio less than 1.000 produces the impression of a "depth" image (i.e., appearing below the plane of the micro-optical system 100). Similarly, along the measurement axis that produces stereo parallax, an icon-lens scale ratio greater than 1,000 will create the impression that the image is suspended above the plane of the micro-optics system 100.

[0021] Theoretical predictions and practical verifications have shown that, compared to the case where the scale ratio is only presented along a single measurement axis, a common lens-icon scale ratio across more than one measurement axis allows the appearance of "depth" or levitation image effects to be revealed over a wider range of viewing angles. Similarly, theoretical predictions and practical verifications have shown that gradually adjusting the lens-icon scale ratio across icon layers can give the image projected by the micro-optical system 100 a three-dimensional appearance, where portions of the projected image appear at different depths relative to the micro-optical system 100.

[0022] Furthermore, tests have shown that the "depth" effect (where the micro-optics have an icon-lens scale ratio of less than 1.000) is perceived by the observer as a more convincing sense of three-dimensionality, but does not appear to move in response to changes in the viewing angle. Similarly, the "floating" or "suspended" effect (where the micro-optics have an icon-lens scale ratio greater than 1.000) is more easily perceived as moving in response to changes in the viewing angle, but at the same time, exhibits a less convincing sense of three-dimensionality.

[0023] There is no real-world analogue for an object that is simultaneously above and below a plane, and the relevant theories do not point to any obvious driving force to achieve the “deep levitation” icon construction, which locally juxtaposes a lens-to-icon scale ratio greater than 1.000 along the first axis with a lens-to-icon scale ratio less than 1.000 along the second axis.

[0024] Since it is recognized that human vision and perception are based on a cognitive middleware (after all, the raw visual data received by our retina is initially upside down and reversed left and right), and this cognitive middleware can be fooled, as demonstrated by magicians, artists, and cognitive scientists, it has been found that by constructing the icon layer of micro-optics to provide seemingly contradictory depth signals, the diachronic defects of depth effects appearing immobile and floating / suspending effects exhibiting an unconvincing sense of three-dimensionality can be overcome.

[0025] Users consistently report that for systems where the icon layer is configured to project an image that embodies both depth effects (i.e., appears to be below the plane of the safety device) and motion effects (appears to move or change in response to changes in the viewer's position) (i.e., a juxtaposition of a scale ratio greater than 1.000 along the first axis and a scale ratio less than 1.000 along a second axis orthogonal to the first axis), the perceived motion of the image is enhanced compared to devices where the icon-lens scale ratio is less than 1.000 across both measurement axes. Furthermore, and as discussed herein, this icon structure has been found to be particularly compatible with coarser, faster inking techniques (i.e., maintaining high-quality projected images).

[0026] In some embodiments of the present disclosure, the micro-optical system 100 includes a sealing layer 140. According to some embodiments, the sealing layer 140 comprises a thin layer (e.g., 2 μm to 50 μm thick) of a substantially transparent material, which abuts a focusing element in a planar array 105 of focusing elements on its lower surface, and includes an upper surface with less curvature variation compared to the planar array 105 of focusing elements (e.g., through smoothing, or by having local undulations on its surface with a larger radius of curvature than the focusing element).

[0027] like Figure 1 As shown in non-limiting examples, in some embodiments, the micro-optical system 100 may be attached to a substrate 150, for example, via an adhesive layer 130, to form a security document 160. According to various embodiments, the substrate 150 may be a sheet of thin paper or a polymer substrate. According to some embodiments, the substrate 150 is a thin, flexible sheet of polymer film (biaxially oriented polypropylene (BOPP)). 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 polyethylene terephthalate (PET) preform suitable for manufacturing credit cards and driver's license types.

[0028] Figure 2A and Figure 2B Four views of an example micro-optical system 200 according to certain embodiments of the present disclosure are illustrated, along with construction details of the micro-optical system. For consistency and ease of cross-reference, Figure 2A and Figure 2B The elements in the accompanying drawings that are common to both are numbered similarly.

[0029] refer to Figure 2A The illustrative example shown illustrates a segment of the micro-optical system 200. In this example, the micro-optical system 200 embodies a reference... Figure 1 The micro-optical system 100 shown in the diagram has a configuration in which the focusing layer comprises an array of circular focusing elements (in this case, a regular array of focusing elements having the same repetition period along a first axis 201 and along a second axis 203). Furthermore, the micro-optical system 200 includes an icon arrangement formed within a holding structure (e.g., cast-cured recesses and bosses formed by embossing and then curing a transparent photocurable material). In this example, the image icon layer embodies a “deeply suspended” icon structure, where the icon-lens scale ratio along the first axis 201 is greater than 1.000, while the icon-lens scale ratio along the second axis 203 is less than 1.000. Moreover, the icons in the array of the icon layer are formed by coarsely over-inking strips (e.g., strips 205a to 205f) of a photocurable material with two or more alternating contrasting colors, wherein, and as discussed in more detail herein, a self-lubricating interface is formed between the still-liquid, uncured photocurable material and the holding structure. Interestingly, when excess photocurable material is scraped off from the top of the retaining structure, over-inking can produce cleaner color transitions (i.e., less trailing and unintended color mixing).

[0030] like Figure 2A As shown, the coarsely inked strips 205a to 205f extend across the width of the micro-optical system 200, parallel to the second axis 203 and alternating between blue and red along the first axis 201 (but other colors are naturally possible and within the scope of this disclosure). In this illustrative example, the widths of the individual strips of the coarsely inked strips 205a-205f are exaggerated for clarity. As used in this disclosure, the term "coarse inking" encompasses a registration accuracy lower than that achievable by curing uncured material through a lens (which theoretically allows for perfect registration accuracy) or by using high-precision inkjet printing (e.g., a registration accuracy of approximately 0.05 mm between the intended and actual positions). Techniques for "coarse inking" according to this disclosure include, but are not limited to: ink jetting with a registration accuracy of less than 0.05 mm (e.g., using a 720 dot / inch inkjet printer), flexographic printing, offset printing, or even block printing. Technicians should understand that while the aforementioned “rough inking” technique offers lower registration accuracy than precise spraying of uncured photocurable materials, it can be completed faster and provides improvements in production throughput and efficiency.

[0031] refer to Figure 2B As an illustrative example, the micro-optical system 200 embodies an icon structure referred to herein as a “depth levitation” icon structure, wherein the icons have an icon-lens scale ratio greater than 1.000 along one axis (the first axis 201 in this example) and a figure-lens scale ratio less than 1.000 along another axis (the second axis 203 in this example). While the first axis 201 and the second axis 203 are perfectly perpendicular to each other in this example, this disclosure contemplates and covers embodiments in which repeating axes with an icon-lens scale ratio greater than 1.000 and repeating axes with an icon-lens scale ratio less than 1.000 are set at a non-parallel angle other than 90 degrees.

[0032] Figure 2B Four views (labeled I-IV) of the micro-optical system 200 are shown as it gradually tilts further about a tilt axis 207, where the tilt axis 207 is parallel to the second axis 203 and, although not shown in the figures, parallel to the line connecting the observer's eye. In other words, when... Figure 2B When observing the micro-optical system 200, a stereoscopic parallax exists along the second axis 203. In this example, the micro-optical system 200 exhibits two composite magnified visual effects. The first effect 209 includes a background effect, in which the four-pointed star, colored according to the roughly inked stripes 205a-205f, exhibits both a "depth" effect (i.e., appears to be below the plane of the micro-optical system 200) and a motion effect, wherein the four-pointed star appears to move up and down in response to tilting about the tilt axis 207. In some embodiments, the repeating axis of the focusing element in the x-direction may be slightly skewed relative to the second axis, resulting in the movement of the star in the first effect 209 exhibiting orthogonal parallax (i.e., perpendicular to the tilt direction, such as lateral movement in response to tilting up and down) motion. Due to the “depth levitation” icon structure, where the icon-lens scale ratio is less than 1.000 along the second axis 203 but greater than 1.000 along the first axis 201, the first effect 209 of the icon appears to “move” in a manner not observed in the “pure depth” icon structure, in which the icon-lens scale ratio is less than 1.000 along both the first and second axes 203. Simultaneously, because the icon-lens scale ratio along the second axis 203 is less than 1.000, the four-pointed star of the first effect 209 convincingly appears below the plane of the micro-optical system 200.

[0033] like Figure 2BAs shown, the micro-optical system 200 also exhibits a second visual effect 211, in which the image icon representing the number "7" displays a "blinking" effect (as described more in detail in U.S. Patent No. 10,173,453), wherein the color within the number "7" appears to change gradually and continuously with the viewing angle around the tilt axis 207. Therefore, the "depth-floating" icon structure described herein can be used in conjunction with icon structures that provide other visual effects. Similarly, in some embodiments, only a portion of the retaining structure forming the array of icon elements is colored using a coarsely inked icon layer, leaving the rest of the icon area to be formed using other techniques, such as curing through a lens (e.g., as described in WIPO Publication No. WO2020252507A1).

[0034] Figure 3 Four views of another example micro-optical system 300 embodying a “deep levitation” icon structure according to an embodiment of this disclosure are shown.

[0035] refer to Figure 3 As an illustrative example, the micro-optical system 300 embodies the reference Figure 1 The overall design shown and described utilizes a "deep levitation" icon structure, where along the first axis 301, the image icon has an icon-lens scale ratio greater than 1.000 relative to the focusing element, while along the second axis 303, the image icon has an icon-lens scale ratio less than 1.000. Additionally, the retaining structure in the icon layer has been coarsely inked with three alternating blue and red stripes (stripes 309A, 309B, and 309C), and transition blending regions 311A-311B, where a slight mixing occurs between the uncured blue photocurable material and the uncured red photocurable material between inking and curing.

[0036] The figure shows four views of the micro-optical system 300 as it appears in response to changes in the observation axis 307 (labeled AD in the figure). In this illustrative example, it is assumed that the observer's eye is separated along a line parallel to the tilt axis 307 and the second axis 303.

[0037] refer to Figure 3 An illustrative example, when viewed through its focused element array (e.g., Figure 1When observed in the focusing element array 105, the micro-optical system 300 projects at least two composite magnified, optically varied image patterns, including a first image pattern 313. This first image pattern includes a wavy background that appears to both move and distort in response to changes in the viewing angle about the tilt axis 307. Furthermore, due to the "depth levitation" icon structure, where the icon-lens scale ratio is greater than 1.000 along the first axis 301 and less than 1.000 along the second axis 303, the wavy pattern of the first image pattern 313 both moves and has a depth appearance.

[0038] As shown in the figure, the micro-optical system 300 projects a second composite magnified image pattern 315, which includes a set of ship rudders that suddenly emerge from the lower ripples of the first image pattern 313 and change from blue to red as they pass through blending regions 311A ​​and 311B, disappearing into the upper ripples of the first image pattern 313. Furthermore, the rudders (e.g., rudder 319) appear to disappear as they approach the edge of the micro-optical system 300. In some embodiments, the disappearance of projected objects as they approach physical boundaries can be coordinated and enhanced by using control patterns to coordinate the positioning of icon elements in an icon layer, as described in U.S. Patent Nos. 10,434,812 and 9,482,792, which are hereby incorporated herein by reference.

[0039] Depending on the implementation, the image icon providing the second image pattern 315 when projected through the focusing element array can be set according to a "depth-floating" icon structure, which has an icon-lens scale ratio of less than 1.000 along the second axis 303 and a scale ratio of greater than 1.000 along the first axis 301; or alternatively, it can be set to emphasize the depth of the first image pattern 313. Furthermore, as shown, the micro-optical system 300 embodies a "slit-to-fit" configuration, wherein the first edge 317A and the second edge 317 are generated by cutting the micro-optical system 300 from a larger piece of micro-optical material, such that the second image pattern can be centered within the micro-optical system 300, and can support the disappearance of steering wheels (e.g., steering wheel 319) near the edge of the system.

[0040] Figure 4 Examples of certain embodiments of this disclosure are illustrated for forming an icon layer (e.g., Figure 1 The arrangement of the image icon 121 in the image is part of the rough inking technique, which is an aspect of over-inking.

[0041] Figure 4This is an enlarged image of a set of partially inked retaining structures 400 suitable for use in micro-optical devices, according to an embodiment of the present disclosure. As shown, the retaining structure 400 includes a series of sailboat-shaped recesses arranged at regular intervals across two axes of the retaining structure 400. In this example, the width of each retaining structure is approximately 25 micrometers. An uncured photocurable material (in this case, UV-curable polyacrylate) of a first color (blue) is applied to the surface of the retaining structure 400 using the tip of a toothpick to create an initial area 410 of uncured blue photocurable material. This is evidenced by the fact that the uncured blue photocurable material is applied with a toothpick, and as can be seen from the initial area 410, the individual retaining structures are not visible through it. In this respect, the initial area 410 can be described as over-inked, where the thickness of the uncured photocurable material provides a material surplus significantly exceeding the material required to fill the retaining structure. Figure 4 Based on photographic evidence and "smearing length," the term "significant surplus" encompasses a volume at least 2.5 times the volume required to fill the retaining structure over a given area. Uncured photocurable material (in this case, red UV-curable polyacrylate) of a second volume 415 is applied to the retaining structure 400 to create a second initial region 420 of uncured red photocurable material. Similar to the first volume 405, the second volume 415 is also over-inked using a toothpick to provide a significant surplus of uncured red photocurable material.

[0042] Then, using a razor blade, the uncured photocurable material in the first volume 405 and the second volume 415 is scraped from starting point 421, dragging to the right along line 425, with the razor blade kept perpendicular to line 425. As expected, the scraping fills the retaining structure 400 within the first region 427 with blue ink and removes most of the ink from the surface of the retaining structure 400 within the first region 427. However, the passage of the razor blade, and the removal of a volume of blue material from the first region 427 into the second region 429 containing the second volume, does not result in an immediate mixing of the red and blue materials. Instead, and as... Figure 4 As shown, a clear visual edge 431 was observed between the first blue region 427 and the second red region 429. In this test image, the mixing of uncured red and blue material only appeared in the third region 453.

[0043] By first over-inking a set of retaining structures with two different colors of uncured photocurable materials, and then scraping them, sharp linear edges can be achieved between areas of different colors. In other words, the visual effects provided by micro-optical devices rely primarily on clean, sharp linear transitions between areas of different colors (e.g., refer to this disclosure). Figures 2A to 3 The described visual effect), while color transitions are secondary to the registration of the focusing elements in the focusing element array, or for applications where the manufacturing target is non-existent, such as... Figure 4 The over-inking technique shown offers the opportunity to increase production speed using a coarser inking technique without sacrificing clear, linear transitions between color zones within a set of retaining structures. To date, research has shown that by over-inking and providing a significant surplus of uncured photocurable material, at least in the color transition regions, the excess uncured photocurable material provides a self-lubricating interface between the squeegee (e.g., a razor blade or scraper) and the upper surface of the retaining structure, allowing the squeegee to glide across the film of uncured photocurable material with little or no friction or turbulence along the interface between the squeegee and the retaining structure. The smooth, turbulent passage of the squeegee through the areas initially inked with a contrasting color material (e.g., initial region 410 and second initial region 420) inhibits mixing of the uncured photocurable material above and around the interface between the squeegee and the retaining structure. However, as the supply of liquid uncured photocurable material gradually decreases, turbulence around the interface increases, and color mixing, such as that shown in the third region 453, is observed. Technicians should understand that by selectively over-inking uncured photocurable material, it is possible to provide sharper and softer, more blurred color transitions within a single icon layer.

[0044] Figure 5 Examples of various embodiments of the present disclosure for the manufacture of micro-optical devices (e.g., referenced herein) are illustrated. Figures 1 to 3 Example method 500 operation of the device under discussion.

[0045] refer to Figure 5 In a non-limiting example, at operation 505, a focused element array is provided (e.g., Figure 1 The focusing element array 105 is described above. In some embodiments, the focusing element array can be provided by molding and curing a matrix of spherical microlenses on an optical spacer layer or other substrate. In some embodiments, the focusing element array (e.g., a reflective focusing element array) can be preformed. The focusing elements in the focusing element array can be provided in a repeating pattern having one or more repeating axes. Furthermore, the focusing element array can be along a first axis (e.g., ...). Figure 2A The first axis 201 in the middle has a first repetition period, and along the second axis (e.g., Figure 2A The second axis (203) has a second repetition period.

[0046] At operation 510, a plurality of retaining structures are provided. The retaining structures (e.g., retaining structure 400) can be provided by casting a bas-relief pattern of recesses, pillars, and bosses that collectively define a space to be filled or coated with an uncured photocurable material of one or more colors, which, once cured, becomes the image icon of the finished micro-optical device. Similar to the focusing elements in the focusing element array provided at operation 505, the space defined by the bas-relief pattern of the retaining structure can have a first repetition period and a second repetition period across a first and a second measurement axis. The icon-lens scale ratio can be determined by dividing by the repetition period of the focusing elements in the focusing element array. In some embodiments, the retaining structure defines an icon structure with a “depth-floating” configuration, wherein on the first axis (e.g., Figure 2A A scale ratio greater than 1.000 is provided on the first axis (201) and a scale ratio less than 1.000 is provided on the second axis (e.g., the second axis 203), thereby achieving stereo parallax.

[0047] At operation 515, the first icon area is formed by inking the first region (e.g., strip 205a) that maintains the structure with an uncured, photocurable material of the first color. According to some embodiments, the first region may be over-inked (e.g., as shown in reference). Figure 4 (As described), and the uncured photocurable material of the first color is roughly inked, for example by low-resolution inkjet, offset printing, flexographic printing, or letterpress printing. As described in this disclosure, clear lines between color areas can be achieved by providing a significant surplus of photocurable material to provide a self-lubricating, low-turbulence interface between the squeegee and the retaining structure.

[0048] At operation 520, a second icon area is formed by inking a second area (e.g., strip 205b) with an uncured, photocurable material of a second color. According to some embodiments, the second area may be over-inked or coarsely inked. Depending on the inking technique used, operations 515 and 520 may be performed simultaneously.

[0049] At operation 525, the first icon area is scraped and cured to form a first set of icons. Depending on the implementation and the optically variable effects provided, the scraping and curing of the first icon area at operation 525 may be performed simultaneously with the scraping and curing of the second icon area at operation 530. Alternatively or separately, some or all of the first or second icon areas may be partially or zone-cured, as described in U.S. Patent No. 11,685,180.

[0050] An example of a micro-optical safety device according to this disclosure includes a micro-optical device comprising: a focusing element array having a first repetition period along a first axis and a second repetition period along a second axis; and an icon layer comprising: a plurality of retaining structures; a first plurality of icons formed as regions of a first-color curable photocurable material disposed on or within a retaining structure of a first region of the plurality of retaining structures; and a second plurality of icons formed as regions of a second-color curable photocurable material disposed on or within a retaining structure of a second region of the plurality of retaining structures. The first plurality of icons have a third repetition period along the first axis and a fourth repetition period along the second axis, the second plurality of icons have a fifth repetition period along the first axis and a sixth repetition period along the second axis, and wherein the first region of the plurality of retaining structures includes a portion of the icon layer separated from the second region of the plurality of retaining structures.

[0051] An example of a micro-optical safety device according to this disclosure includes a micro-optical device comprising a first edge extending parallel to a first axis and a second edge extending parallel to the first axis. The second axis is perpendicular to, or substantially perpendicular to, the first axis, a third repetition period greater than the first repetition period, a fourth repetition period less than the second repetition period, a fifth repetition period greater than the first repetition period, and a sixth repetition period less than the second repetition period.

[0052] Examples of micro-optical safety devices according to this disclosure include micro-optical devices, wherein the third repetition period is the same as the fifth repetition period, and wherein the fourth repetition period is the same as the sixth repetition period.

[0053] Examples of micro-optical security devices according to this disclosure include a micro-optical device comprising a third plurality of icons formed between the first edge and the second edge, wherein when viewed through the focusing element array, the third plurality of icons projects a first composite magnified image of at least one of the third plurality of icons, and when viewed across a first viewing angle range, the first composite magnified image appears to move along the second axis.

[0054] Examples of micro-optical security devices according to this disclosure include micro-optical devices, wherein the first composite magnified image becomes invisible before contacting at least one of the first edge or the second edge.

[0055] Examples of micro-optical security devices according to this disclosure include micro-optical devices, wherein the first composite magnified image becomes invisible just before, just after, or upon contact with at least one of the first edge or the second edge.

[0056] Examples of micro-optical safety devices according to this disclosure include a micro-optical device comprising a fourth plurality of icons formed between the first edge and the second edge, wherein when viewed through the focusing element array, the fourth plurality of icons projects a second composite magnified image of at least one of the fourth plurality of icons, the second composite magnified image appearing to float between the first edge and the second edge, wherein when viewed through the focusing element array, the second composite magnified image appears not to contact at least one of the first edge or the second edge.

[0057] Examples of micro-optical safety devices according to this disclosure include micro-optical devices, wherein a first region of a plurality of retaining structures is adjacent to a second region of the plurality of retaining structures along a boundary parallel to a second axis, or wherein a first region of the plurality of retaining structures is adjacent to a blending region along a second boundary parallel to a second axis, and a second region of the plurality of retaining structures is adjacent to the blending region along a third boundary parallel to a second axis.

[0058] Examples of methods according to this disclosure include a method comprising: providing a focusing element array having a first repetition period along a first axis and a second repetition period along a second axis; providing a plurality of holding structures within or near the focal plane of the focusing elements in the focusing element array; forming a first plurality of icons by inking a first region of the plurality of holding structures with an uncured photocurable material of a first color; forming a second plurality of icons by inking a second region of the plurality of holding structures with an uncured photocurable material of a second color; curing the uncured photocurable material of the first color; and curing the uncured photocurable material of the second color, wherein the first plurality of icons have a third repetition period along the first axis and a fourth repetition period along the second axis, wherein the second plurality of icons have a fifth repetition period along the first axis and a sixth repetition period along the second axis, wherein the first region of the plurality of holding structures includes a portion of the icon layer separated from the second region of the plurality of holding structures.

[0059] Examples of micro-optical safety devices according to this disclosure include a micro-optical device comprising: forming a first edge extending parallel to a first axis; and forming a second edge extending parallel to the first axis, wherein the second axis is perpendicular to the first axis, wherein a third repetition period is greater than the first repetition period, wherein a fourth repetition period is less than the second repetition period, wherein a fifth repetition period is greater than the first repetition period, and wherein a sixth repetition period is less than the second repetition period.

[0060] An example of a micro-optical safety device according to this disclosure includes a micro-optical device in which a first region and a second region of a plurality of retaining structures are simultaneously inked, wherein inking the first region of the plurality of retaining structures includes over-inking the first region of the plurality of retaining structures with a layer thickness sufficient to create a first self-lubricating interface between the uncured photocurable material of the first color and the retaining structure, wherein inking the second region of the plurality of retaining structures includes over-inking the second region of the plurality of retaining structures with a layer thickness sufficient to create a second self-lubricating interface between the uncured photocurable material of the second color and the retaining structure, and further includes scraping excess photocurable material from the first region and the second region of the plurality of retaining structures.

[0061] Examples of micro-optical security devices according to this disclosure include micro-optical devices in which excessive inking of the first area includes applying an uncured photocurable material of the first color by at least one of the following: inkjet printing, offset printing, flexographic printing, gravure printing, spraying, offset printing, or letterpress printing.

[0062] An example of a micro-optical safety device according to this disclosure includes a micro-optical device, wherein a first region extends from a first edge to a second edge, wherein a second region extends from the first edge to the second edge, wherein excess photocurable material is scraped from the first edge to the second edge in a direction not parallel to the second axis.

[0063] Examples of micro-optical safety devices according to this disclosure include micro-optical devices, wherein the third repetition period is the same as the fifth repetition period, and wherein the fourth repetition period is the same as the sixth repetition period.

[0064] Examples of micro-optical security devices according to this disclosure include a micro-optical device comprising providing a third plurality of icons formed between the first edge and the second edge, wherein when viewed through the focusing element array, the third plurality of icons project a first composite magnified image of at least one of the third plurality of icons, and when viewed across a first viewing angle range, the first composite magnified image appears to move along the second axis.

[0065] Examples of micro-optical security devices according to this disclosure include micro-optical devices, wherein the first composite magnified image becomes invisible before contacting at least one of the first edge or the second edge.

[0066] Examples of micro-optical safety devices according to this disclosure include a micro-optical device comprising providing a fourth plurality of icons formed between a first edge and a second edge, wherein when viewed through the focusing element array, the fourth plurality of icons projects a second composite magnified image of at least one of the fourth plurality of icons, the second composite magnified image appearing to float between the first edge and the second edge, wherein when viewed through the focusing element array, the second composite magnified image appears not to contact at least one of the first edge or the second edge.

[0067] Examples of micro-optical safety devices according to this disclosure include micro-optical devices, wherein a first region of a plurality of retaining structures is adjacent to a second region of the plurality of retaining structures along a boundary parallel to a second axis, or wherein a first region of the plurality of retaining structures is adjacent to a blending region along a second boundary parallel to a second axis, and a second region of the plurality of retaining structures is adjacent to the blending region along a third boundary parallel to a second axis.

[0068] Nothing described in this application should be construed as implying that any particular element, step, or function is an essential element that must be included within the scope of the claims. The scope of the patent subject matter is defined only by the claims. Furthermore, unless the exact words “component for…” are followed by a participle, none of the claims are intended to invoke 35 USC §112(f).

Claims

1. A micro-optical device, the micro-optical device comprising: A focusing element array having a first repetition period along a first axis and a second repetition period along a second axis; as well as Icon layer, the icon layer including: Multiple retaining structures; The first plurality of icons are formed as areas of a first-color, curable, photocurable material disposed on or within the first region of the plurality of retaining structures; and The second plurality of icons are formed as areas of a second-color, curable, photocurable material disposed on or within the second region of the plurality of retaining structures. The first plurality of icons have a third repetition period along the first axis and a fourth repetition period along the second axis. The second plurality of icons have a fifth repetition period along the first axis and a sixth repetition period along the second axis, and The first region of the plurality of retaining structures includes a portion of the icon layer that is separated from the second region of the plurality of retaining structures.

2. The micro-optical device as claimed in claim 1, further comprising: A first edge extends parallel to the first axis; as well as The second edge extends parallel to the first axis. The second axis is perpendicular to the first axis. The third repetition period is longer than the first repetition period. The fourth repetition period is shorter than the second repetition period. The fifth repetition period is greater than the first repetition period, and The sixth repetition period is shorter than the second repetition period.

3. The micro-optical device as described in claim 2, wherein: The third repetition cycle is the same as the fifth repetition cycle, and The fourth repeating cycle is the same as the sixth repeating cycle.

4. The micro-optical device of claim 2, further comprising a third plurality of icons formed between the first edge and the second edge. When viewed through the focusing element array, the third plurality of icons project a first composite magnified image of at least one of the third plurality of icons, and when viewed across a first viewing angle range, the first composite magnified image appears to move along the second axis.

5. The micro-optical device of claim 4, wherein the first composite magnified image becomes invisible before contacting at least one of the first edge or the second edge.

6. The micro-optical device of claim 2, further comprising a fourth plurality of icons formed between the first edge and the second edge. When viewed through the focusing element array, the fourth plurality of icons project a second composite magnified image of at least one of the fourth plurality of icons, the second composite magnified image appearing to float between the first edge and the second edge, and When viewed through the focusing element array, the second composite magnified image appears not to touch at least one of the first edge or the second edge.

7. The micro-optical device as claimed in claim 1, wherein: The first region of the plurality of retaining structures is adjacent to the second region of the plurality of retaining structures along a boundary parallel to the second axis, or The first region of the plurality of retaining structures is adjacent to the blending region along a second boundary parallel to the second axis, and the second region of the plurality of retaining structures is adjacent to the blending region along a third boundary parallel to the second axis.

8. A method for manufacturing a micro-optical device, the method comprising: A focusing element array is provided, wherein the focusing element array has a first repetition period along a first axis and a second repetition period along a second axis; Multiple holding structures are provided within or near the focal plane of the focusing element in the focusing element array; The first plurality of icons are formed by inking the first areas of the plurality of retaining structures with an uncured photocurable material of the first color; The second plurality of icons are formed by inking the second areas of the plurality of retaining structures with an uncured photocurable material of the second color; The uncured photocurable material of the first color is cured; as well as The uncured photocurable material of the second color is then cured. The first plurality of icons have a third repetition period along the first axis and a fourth repetition period along the second axis. The second plurality of icons have a fifth repetition period along the first axis and a sixth repetition period along the second axis, and The first region of the plurality of retaining structures includes a portion of the icon layer that is separated from the second region of the plurality of retaining structures.

9. The method of claim 8, further comprising: Forming a first edge that extends parallel to the first axis; as well as A second edge is formed that extends parallel to the first axis. The second axis is perpendicular to the first axis. The third repetition period is longer than the first repetition period. The fourth repetition period is shorter than the second repetition period. The fifth repetition period is greater than the first repetition period, and The sixth repetition period is shorter than the second repetition period.

10. The method as described in claim 8, The first region and the second region of the plurality of retaining structures are simultaneously inked. Applying ink to the first area of ​​the plurality of retaining structures includes applying excess ink to the first area of ​​the plurality of retaining structures with a layer thickness sufficient to create a first self-lubricating interface between the uncured photocurable material of the first color and the retaining structure. The inking of the second region of the plurality of retaining structures includes applying excess ink to the second region of the plurality of retaining structures with a layer thickness sufficient to create a second self-lubricating interface between the uncured photocurable material of the second color and the retaining structure; and The method further includes: Excess photocurable material is scraped from the first and second regions of the plurality of retaining structures.

11. The method of claim 10, wherein over-inking the first region comprises applying an uncured photocurable material of the first color by at least one of: inkjet printing, offset printing, flexographic printing, gravure printing, spraying, offset printing, or letterpress printing.

12. The method of claim 10, wherein: The first region extends from the first edge to the second edge. The second region extends from the first edge to the second edge, and The excess photocurable material is scraped from the first edge to the second edge in a direction not parallel to the second axis.

13. The method of claim 9, wherein: The third repetition cycle is the same as the fifth repetition cycle, and The fourth repeating cycle is the same as the sixth repeating cycle.

14. The method of claim 9, further comprising providing a third plurality of icons formed between the first edge and the second edge. When viewed through the focusing element array, the third plurality of icons project a first composite magnified image of at least one of the third plurality of icons, and when viewed across a first viewing angle range, the first composite magnified image appears to move along the second axis.

15. The method of claim 14, wherein the first composite magnified image becomes invisible before contacting at least one of the first edge or the second edge.

16. The method of claim 9, further comprising providing a fourth plurality of icons formed between the first edge and the second edge. When viewed through the focusing element array, the fourth plurality of icons project a second composite magnified image of at least one of the fourth plurality of icons, the second composite magnified image appearing to float between the first edge and the second edge, and When viewed through the focusing element array, the second composite magnified image appears not to touch at least one of the first edge or the second edge.

17. The method of claim 8, wherein: The first region of the plurality of retaining structures is adjacent to the second region of the plurality of retaining structures along a boundary parallel to the second axis, or The first region of the plurality of retaining structures is adjacent to the blending region along a second boundary parallel to the second axis, and the second region of the plurality of retaining structures is adjacent to the blending region along a third boundary parallel to the second axis.

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