Use of nanoparticles to optimize microoptics (MO) focus by adjusting the refractive index of polymer matrix layers.

Abstract

To provide technology that solves problems in designing and manufacturing specific micro-optical security devices that include achieving desirable properties of a final product against opportunities and constraints imposed by available manufacturing techniques and physical laws, for example.SOLUTION: A security device 100 includes image icon arrays 110a, 110b, refractive image icon focusing element arrays 120, and a sealing layer 125. The refractive image icon focusing element arrays are disposed above the image icon arrays such that a part of the refractive image icon focusing element arrays projects a synthetic image, and the refractive image icon focusing element arrays contact the sealing layer along a non-planar boundary. Furthermore, at least one of the refractive image icon focusing element arrays and the sealing layer includes an organic resin mixture having a first refractive index, at least one of the refractive image icon focusing element arrays and the sealing layer includes a low refractive index material, and the low refractive index material has a second refractive index.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] This disclosure relates, in general, to improving the performance of security devices such as micro-optical strips that are applied to or otherwise incorporated into security documents to provide an authenticity mark for anti-counterfeiting purposes. More specifically, this disclosure relates, but is not limited to, to the use of low refractive index ("low RI") materials to form one or more layers of micro-optical security devices. [Background technology]

[0002] In many cases, the challenges of designing and manufacturing specific micro-optical security devices involve negotiating trade-offs between achieving desired characteristics of the final product and the opportunities and constraints imposed by available manufacturing techniques and physical laws. For example, manufacturers of security documents (e.g., banknotes, checks, and other documents indicating the need for a reliable seal of authenticity) want a micro-optical security device that is thin, durable, counterfeit-resistant, and visually appealing. At the same time, the properties of the materials used, in combination with the physical laws used to construct the micro-optical security device, can impose constraints on the performance characteristics of the final product. In one non-limiting embodiment, a lens made of a low refractive index material may be thicker than a lens of the same focal length made of a high refractive index material. In a further non-limiting embodiment, the interaction between light waves and the constituent materials of the lens may cause chromatic aberration, thereby causing the focal length of the lens to change over different wavelengths of light.

[0003] Considering the above, tuning the physical properties of materials for fabricating micro-optical security devices (e.g., component thickness and refractive index) offers an untapped opportunity to push the limits and achieve a larger set of desirable end-product characteristics (e.g., overall thickness, resistance to contamination) within the constraints imposed by the application of physical laws to the selected materials. [Overview of the project]

[0004] This disclosure, without limitation, illustrates embodiments of a microoptics system and a method of use that utilize a low refractive index ("RI") material in one or more constituent layers of the microoptics system.

[0005] In the first embodiment, the security device includes one or more image icon arrays, one or more refractive image icon focusing element arrays, and a sealing layer. Furthermore, one or more refractive image icon focusing element arrays are arranged on one or more image icon arrays such that a portion of one or more refractive image icon focusing element arrays projects a composite image of a portion of one or more image icon arrays. Furthermore, one or more refractive image icon focusing element arrays are in contact with the sealing layer along a non-planar boundary. At least one of the one or more refractive image icon focusing element arrays and the sealing layer comprises a mixture of an organic resin having a first refractive index and nanoparticles, and at least one of the one or more refractive image icon focusing element arrays and the sealing layer comprises a low refractive index material, the low refractive index material having a second refractive index.

[0006] In a second embodiment, the security device includes one or more image icon arrays, one or more refractive image icon focusing element arrays, and one or more refractive image icon focusing element arrays comprising a mixture of organic resin and nanoparticles. One or more refractive image icon focusing element arrays are arranged on one or more image icon arrays such that a portion of one or more refractive image icon focusing element arrays projects a composite image of a portion of one or more image icon arrays. The mixture of organic resin and nanoparticles has a refractive index greater than 1.5.

[0007] In a third embodiment, the security document includes a substrate and a security device. The security device includes one or more image icon arrays, one or more refractive image icon focusing element arrays, and a sealing layer. Furthermore, one or more refractive image icon focusing element arrays are arranged on one or more image icon arrays such that a portion of one or more refractive image icon focusing element arrays projects a composite image of a portion of one or more image icon arrays. Furthermore, one or more refractive image icon focusing element arrays are in contact with the sealing layer along a non-planar boundary. In addition, at least one of the one or more refractive image icon focusing element arrays and the sealing layer includes an organic resin having a first refractive index and a nanoparticle mixture.

[0008] In a fourth embodiment, the security document includes a substrate and a security device. The security device includes one or more image icon arrays, one or more refractive image icon focusing element arrays, and one or more refractive image icon focusing element arrays comprising a mixture of organic resin and nanoparticles. One or more refractive image icon focusing element arrays are arranged on one or more image icon arrays such that a portion of one or more refractive image icon focusing element arrays projects a composite image of a portion of one or more image icon arrays. The mixture of organic resin and nanoparticles has a refractive index greater than 1.5.

[0009] In the fifth embodiment, the security device includes one or more image icon arrays, one or more refractive image icon focusing element arrays, and a spacer layer disposed between one or more image icon arrays and one or more refractive image icon focusing element arrays. The spacer layer comprises a mixture of an organic resin and nanoparticles. In addition, one or more refractive image icon focusing element arrays are disposed on one or more image icon arrays such that a portion of one or more refractive image icon focusing element arrays projects a composite image of a portion of one or more image icon arrays. Furthermore, the mixture of the organic resin and nanoparticles has a refractive index greater than 1.5.

[0010] In the sixth embodiment, the security document includes a substrate, one or more image icon arrays, one or more refractive image icon focusing element arrays, and a spacer layer disposed between one or more image icon arrays and one or more refractive image icon focusing element arrays. The spacer layer comprises a mixture of an organic resin and nanoparticles. In addition, one or more refractive image icon focusing element arrays are disposed on one or more image icon arrays such that a portion of one or more refractive image icon focusing element arrays projects a composite image of a portion of one or more image icon arrays. Furthermore, the mixture of the organic resin and nanoparticles has a refractive index greater than 1.5.

[0011] In the seventh embodiment, the security device includes an image icon focusing element array, each image icon focusing element in the image icon focusing element array is associated with a focal path, and the image icon layer includes one or more image icons associated with a first characteristic color and one or more image icons associated with a second characteristic color, and includes one or more regions between the image icons containing a certain volume of substantially colorless material. Additionally, at a first viewing angle, the color is visible through each image icon focusing element, and the color visible through each image icon focusing element at the first viewing angle is based on one or more of the first characteristic color, the second characteristic color, or substantially colorless material.

[0012] Other technical features may be readily apparent to those skilled in the art from the following drawings, description, and claims.

[0013] Before providing the following detailed explanation, it may be beneficial to present the definitions of certain words and phrases used throughout this patent document. The term “coupling” and its derivatives refer to two or more elements, whether or not they are in physical contact with each other. This refers to any direct or indirect communication between the elements mentioned above. The terms "comprise" and "include," as well as their derivatives, mean unrestricted inclusion. The term "or" means comprehensive and / or. The phrase "associated with," as well as its derivatives, means "include." "to include", "to be included within", "to connect with", "to contain", "to be contained within", "to connect to or with", "to couple to or with", "to be communicable with", "to cooperate with", "to interleave", "to juxtapose", "closest "to be proximate to", "to be bound to or with", "to have", "to have a property of", "to have a relationship with It has meanings that include "a relationship to or with" and "at least one of" The phrase "one of)" is used with a list of items, and refers to the listed items. This means that one or more different combinations of 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 combination of A, B, C, A and B, A and C, B and C, and A, B, and C.

[0014] Definitions of other specific words and phrases are provided throughout this patent document. Those skilled in the art should understand that, in many but not most cases, such definitions apply to the prior and future use of the words and phrases thus defined.

[0015] For a more complete understanding of the present disclosure and the advantages thereof, reference is made to the following description taken in conjunction with the accompanying drawings herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] [Figure 1A] FIG. 1 illustrates an example of elements of a micro-optical security device and a security document including the micro-optical security device, according to certain embodiments of the present disclosure. [Figure 1B] FIG. 2 illustrates an example of elements of a micro-optical security device and a security document including the micro-optical security device, according to certain embodiments of the present disclosure. [Figure 1C] FIG. 3 illustrates an example of elements of a micro-optical security device and a security document including the micro-optical security device, according to certain embodiments of the present disclosure. [Figure 2] FIGS. 4A to 4D are diagrams illustrating aspects of adjusting optical properties of a refractive image icon light condensing element according to various embodiments of the present disclosure. [Figure 3] FIG. 5 illustrates aspects of chromatic aberration associated with light of different wavelengths passing through a refractive image icon light condensing element. [Figure 4] FIG. 6 shows an example of a plurality of image icon arrays located under a refractive image icon light condensing element with adjusted refractive index according to some embodiments of the present disclosure. [Figure 5] FIG. 7 illustrates aspects of visual effects in a composite image created by a micro-optical security device according to certain embodiments of the present disclosure. [Figure 6] FIGS. 8A to 8E illustrate an example of a configuration of a micro-optical security device having a sealing layer adjusted by nanoparticles according to various embodiments of the present disclosure. [Figure 7] FIGS. 9A to 9E illustrate an example of a configuration of a micro-optical security device having a refractive image icon light condensing element adjusted by nanoparticles according to certain embodiments of the present disclosure. [Figure 8]FIG. 1 illustrates an example of a composite image including a combination of a characteristic color of a first image icon array associated with a first characteristic color and a characteristic color of a second image icon array associated with a second characteristic color, in accordance with various embodiments of the present disclosure. [Figure 9A] FIG. 2 illustrates an aspect of generating a composite image including a combination of a characteristic color of a first image icon array associated with a first characteristic color and a characteristic color of a second image icon array associated with a second characteristic color. [Figure 9B] FIG. 3 illustrates an aspect of generating a composite image including a combination of a characteristic color of a first image icon array associated with a first characteristic color and a characteristic color of a second image icon array associated with a second characteristic color. [Figure 9C] FIG. 4 illustrates an aspect of generating a composite image including a combination of a characteristic color of a first image icon array associated with a first characteristic color and a characteristic color of a second image icon array associated with a second characteristic color. [Figure 10A] FIG. 5 illustrates an example of a micro-optical security device, in accordance with various embodiments of the present disclosure. [Figure 10B] FIG. 6 illustrates an example of a micro-optical security device, in accordance with various embodiments of the present disclosure. DETAILED DESCRIPTION OF EMBODIMENTS

[0017] The various embodiments used to explain the principles of the present disclosure in FIGS. 1A to 10 discussed below and in this patent document are for illustrative purposes only, and should in no way be construed as limiting the scope of the present disclosure.

[0018] FIGS. 1A, 1B and 1C illustrate examples of elements of a micro-optical security device and a security document including the micro-optical security device, in accordance with particular embodiments of the present disclosure. For convenience, structural elements common to the embodiments of FIGS. 1A, 1B and 1C are numbered similarly (e.g., substrate 105).

[0019] Referring to the non-limiting embodiment in Figure 1A, the micro-optical security device 100 and the security document 101 can be constructed as a layered combination of some or all of the elements shown in the exemplary embodiment in Figure 1A.

[0020] As shown in the exemplary embodiment of Figure 1A, the security document 101 includes a substrate 105 on which a micro-optical security device 100 is mounted. As used in this disclosure, the term “security document” encompasses documents that utilize a micro-optical security device to provide a visual mark of authenticity for the purpose of preventing forgery of the document (e.g., a composite image created by the spatial alignment of one or more image icon arrays and one or more refractive image icon focusing elements). Examples of security documents, but not limited to, include banknotes, passports, tickets, collectible trading cards, and ID cards (e.g., driver’s licenses).

[0021] According to certain embodiments, the substrate 105 is a sheet of a thin, flexible fibrous material such as currency paper. According to some embodiments, the substrate 105 is a thin, flexible sheet of a polymer film of biaxially oriented polypropylene (BOPP). In various embodiments, the substrate 105 is part of a synthetic paper material such as TESLIN®. According to some embodiments, the substrate 105 is part of a polymer card material such as a polyethylene terephthalate (PET) blank of a type suitable for making credit cards and driver's licenses.

[0022] Referring to a non-limiting embodiment in Figure 1A, the micro-optical security device 100 includes one or more image icon arrays (110a and 110b). According to various embodiments, one or more image icon arrays include colored regions (e.g., colored regions 112) of a pigmented material arranged in a predetermined pattern (e.g., as an icon design that is synthetically amplified by one or more refractive image icon focusing element arrays). According to various embodiments, the colored regions 112 include a molded volume of pigmented image material (e.g., a UV-curable polymer containing a pigment). Certain Embodiments Therefore, the colored region 112 has a width of approximately 1 μm or more.

[0023] According to certain embodiments, each of the one or more image icon arrays 110a and 110b is formed as a separate layer. In some embodiments, the image icon array is formed by creating a layer structure of icons (e.g., embossing and curing a polymer matrix) to create retaining structures such as recesses or voids for holding one or more pigment-containing polymer materials, and then applying one or more pigment-containing polymer materials to create colored regions (e.g., colored regions 112) that collectively define the array of image icons.

[0024] In various embodiments, for a given image icon array, the pigment-containing polymer material used to generate a colored region (e.g., colored region 112) is configured such that a large portion or all of the colored region is filled with the polymer material of the characteristic color. As used in this disclosure, the term “characteristic color” includes a color associated with a given wavelength of light, or a color associated with a range of wavelengths of light where the focal length of a refractive image icon focusing element matches the depth of the image icon array in the micro-optical security device 100.

[0025] As shown in the non-limiting embodiment of Figure 1A, in certain embodiments according to the present disclosure, the micro-optical security device 100 comprises two stacked image icon arrays (110a and 110b). Embodiments according to the present disclosure are not limited to two image icon arrays, and embodiments having fewer or more image icon arrays are within the intended scope of the present disclosure.

[0026] According to various embodiments, the refractive index of a polymer matrix used to create a holding structure (e.g., holding structure 114) of one or more pigment-containing materials in one image icon array (e.g., image icon array 110b) can be adjusted by adding nanoparticles to the matrix to improve the focus of light on another image icon array (e.g., image icon array 110a).

[0027] In certain embodiments of this disclosure, the micro-optical security device 100 is attached to the substrate 105 by adhesive bonding to the bottom surface of an image icon array (e.g., image icon array 110a). In some embodiments, the micro-optical security device is attached to the substrate 105 as part of the manufacturing process of the substrate 105 (e.g., as a windowed security thread in a sheet of currency paper).

[0028] Referring to the non-limiting embodiment in Figure 1A, in certain embodiments, the micro-optical security device 100 includes an optical spacer 115. According to some embodiments, the optical spacer 115 comprises a thin film of a transparent material (e.g., polyester) on which a polymer matrix is ​​coated, molded (e.g., by embossing), and cured to generate a retaining structure (e.g., retaining structure 114) for refractive image icon focusing elements and / or pigment-containing materials. In some embodiments, the optical spacer 115 is formed as a layer of polymer matrix and integrated with one or more refractive image icon focusing element arrays. According to various embodiments, the optical properties of the micro-optical security device 100 of the optical spacer 115 formed from the polymer matrix (e.g., quality of focusing on the arrangement of image icons or internal reflections within the security device) may be tuned by varying the thickness of the optical spacer 115 and / or adjusting the concentration of nanoparticles in the polymer matrix used to form the optical spacer 115. According to a particular embodiment, the optical spacer 115 is made from a polymer matrix suitable for use in forming the sealing layer 125 or the refractive focuser 121. In various embodiments, the matrix composition used to form the optical spacer 115 is specifically formulated so as not to contain materials having polarizing elements such as iodine, bromine, chlorine, or sulfur.

[0029] In addition, while the non-limiting embodiment of Figure 1A shows the micro-optical security device 100 including an optical spacer 115, embodiments according to this disclosure are not limited thereto. In certain embodiments, the optical spacer 115 may be omitted. Furthermore, while the non-limiting embodiment of Figure 1A shows the optical spacer 115 as physically distinct from the refractive image icon focusing element array, embodiments according to this disclosure are not limited thereto, and embodiments in which one or more refractive image icon focusing element arrays are formed by generating a structural deformation of the refractive index of the material used to create the optical spacer 115 are within the intended scope of this disclosure.

[0030] Referring to the exemplary embodiment in Figure 1A, in a particular embodiment, the micro-optical security device 100 comprises one or more refractive image icon focusing element arrays 120 arranged on one or more image icon arrays (e.g., image icon arrays 110a and 110b) such that a portion of one or more refractive image icon focusing element arrays projects a composite image of a portion of one or more image icon arrays. As discussed elsewhere in this disclosure, in a particular embodiment, two or more composite images are generated, each composite image being associated with a characteristic color.

[0031] As shown in the non-limiting embodiment of Figure 1A, the refractive image icon focusing element array 120 includes a plurality of individual refractive focusing elements (e.g., refractive focusing elements 121) arranged in a predetermined pattern with respect to at least one image icon array (e.g., image icon array 110a). In certain embodiments, the colored regions of the image icon array are substantially the same in the plane defining the x and y axes of the coordinate system. In some embodiments, the centers of the refractive focusing elements are located at different coordinates on the z axis, but with x and y values ​​common to the image icons. In some embodiments, the composite image may appear to be in the plane of the micro-optical security device 100. In some embodiments, the distance between the centers of the refractive focusing elements (i.e., the pitch) may be slightly different from the repetition distance of the image icons, and the composite image(s) may appear to be above or below the plane of the micro-optical security device 100. In various embodiments, the center of the refractive focuser may be rotated slightly (for example, by an angle of less than 1 degree) relative to the image icon to produce orthoparallax motion effects.

[0032] In certain embodiments, the refractive focuser 121 includes a certain volume of cured polymer matrix having at least one outer surface that defines a non-planar boundary between a region of a medium having a first refractive index and a region of a medium having a second refractive index. In a non-limiting embodiment of Figure 1A, the refractive focuser 121 is shown to have a planar bottom surface and a radially symmetrically curved top surface, but embodiments according to the present disclosure are not limited thereto. According to some embodiments, the refractive focuser may be a lenticle of a lenticular array, or may be curved, for example, on its top and bottom surfaces.

[0033] In some embodiments of this disclosure, the refractive focuser 121 is formed from a polymer matrix and, upon curing, has a refractive index of less than 1.5. Examples of materials for use in such a polymer matrix, having a refractive index of 1.5 or less, include, but are not limited to, isodecyl acrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polyester tetraacrylate, trimethylpropane triacrylate, and hexanediol diacrylate. Further examples of materials suitable for forming the refractive focuser 121 include acrylic, acrylic polyester, acrylic urethane, epoxy, polycarbonate, and polypropylene. Examples include substantially transparent or transparent, colored or colorless polymers such as polyester and urethane. Further examples of materials that can be used to form a matrix for forming the refractive light-gathering element 121 include, but are not limited to, acrylate monomers, acrylate oligomers, O-phenylphenoxyethyl acrylate, phenylthioethyl acrylate, bis-phenylthioethyl acrylate, cumin phenoxyethyl acrylate, biphenyl methyl acrylate, bisphenol A epoxy acrylate, fluorene-type acrylate, brominated acrylate, halogenated acrylate, melamine acrylate, and combinations thereof. According to a particular embodiment, the matrix composition used to form the refractive light-gathering element 121 is specifically formulated so as not to contain materials having polarizing elements such as iodine, bromine, chlorine, or sulfur. As used in this disclosure, the term “polarizing element” includes elements with a polarizability greater than carbon.

[0034] In various embodiments of this disclosure, the refractive index of the material constituting the refractive light focusing element 121 can be adjusted or controlled by adding or adjusting the concentration of nanoparticles in the material mixture (e.g., polymer matrix) used to form the refractive light focusing element 121. According to some embodiments, the refractive index of the material constituting the refractive light focusing element can be controlled, for example, by adding inorganic nanoparticles having a particle size of 100 nm or less to the mixture. Examples of inorganic nanoparticles that can be added to the material mixture include, but are not limited to, nanoparticles of aluminum oxide, zirconium dioxide, titanium dioxide, zinc sulfide, or zinc telluride. According to certain embodiments, by adding nanoparticles to the material mixture, the refractive index of the material mixture used to form the refractive light focusing element 121 can be increased from less than 1.5 to 1.7 or higher. In some embodiments, a refractive index greater than 1.7 is possible by adding nanoparticles to an organic resin.

[0035] Referring to the non-limiting embodiment in Figure 1A, in various embodiments of the present disclosure, the micro-optical security device 100 further comprises a sealing layer 125. According to various embodiments, the sealing layer 125 includes a smooth, or substantially planar, top surface 127 and a non-planar bottom surface 129 that provides a substantially continuous non-planar boundary between the sealing layer 125 and the refractive image icon focusing element array 120. According to some embodiments, the sealing layer 125 has a non-planar top surface having less of a “pocket” than the boundary between the sealing layer 125 and the refractive image icon focusing element array 120.

[0036] In certain embodiments, the sealing layer 125 protects one or more refractive image icon focusing element arrays 120 and contributes to the robustness and durability of the micro-optical security device 100 by eliminating spaces where dirt, grease, and other contaminants associated with the use and distribution of security documents can accumulate in the spaces between the refractive focusing elements (e.g., refractive focusing elements 121). Furthermore, in certain embodiments, the sealing layer 125 allows for the use of additional material layers, such as an uppermost adhesive, without significantly affecting the focal length of the system.

[0037] According to various embodiments, the sealing layer 125 contacts the refractive focusers of a refractive image icon focuser array (e.g., refractive image icon focuser array 120) along a non-planar boundary at least partially defined by the bottom surface 129 of the sealing layer 125. In certain embodiments, the sealing layer 125 is formed from a material having a refractive index different from that of the material used to produce the refractive focusers 121.

[0038] In various embodiments, the sealing layer 125 is formed from a polymer matrix and, upon curing, has a refractive index of less than 1.5. Examples of materials for use in such a polymer matrix, which have a refractive index of 1.5 or less, are not limited to, but include, Examples include sodecyl acrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polyester tetraacrylate, trimethylolpropane triacrylate, and hexanediol diacrylate. Further examples of materials suitable for forming the sealing layer 125 include substantially transparent or transparent, colored or colorless polymers such as acrylic, acrylic polyester, acrylic urethane, epoxy, polycarbonate, polypropylene, polyester, and urethane. Further examples of materials that can be used to form the matrix for forming the sealing layer 125 include, but are not limited to, acrylate monomers, acrylate oligomers, O-phenylphenoxyethyl acrylate, phenylthioethyl acrylate, bis-phenylthioethyl acrylate, cumin phenoxyethyl acrylate, biphenyl methyl acrylate, bisphenol A epoxy acrylate, fluorene-type acrylate, brominated acrylate, halogenated acrylate, melamine acrylate, and combinations thereof. According to a particular embodiment, the matrix composition used to form the sealing layer 125 is specifically formulated so as not to contain materials having polarizing elements such as iodine, bromine, chlorine, or sulfur.

[0039] According to certain embodiments, the sealing layer 125 may be formed from a material that produces a large difference in refractive index (e.g., a difference greater than 0.1) between the sealing layer 125 and one or more refractive image icon focusing element arrays 120. According to certain embodiments, suitable low-RI materials for use in the sealing layer 125 include materials having an RI between 1.3 and 1.4, or materials having an RI less than 1.3. Examples of suitable low-RI materials, but not limited to, include fluorinated acrylates and blends of fluorinated urethane acrylates, which are measured to have a refractive index in the range of 1.3 to 1.135. Further examples of suitable low-RI materials, but not limited to, include certain perfluoropolyether compounds, such as perfluoropolyether caprolactone diacrylate.

[0040] In various embodiments of this disclosure, the refractive index of the material constituting the sealing layer 125 can be adjusted or controlled by adding or adjusting the concentration of nanoparticles in the material mixture (e.g., polymer matrix) used to form the sealing layer 125. According to some embodiments, the refractive index of the material including the refractive focuser can be adjusted, for example, by adding inorganic nanoparticles having a particle size of 100 nm or less to the mixture. Examples of inorganic nanoparticles that can be added to the material mixture include, but are not limited to, nanoparticles of aluminum oxide, zirconium dioxide, titanium dioxide, zinc sulfide, or zinc telluride. According to certain embodiments, by adding nanoparticles to the material mixture, the refractive index of the material mixture used to form the sealing layer 125 can be increased from less than 1.5 to 1.7 or higher. In some embodiments, a refractive index greater than 1.7 is possible by adding nanoparticles to an organic resin. Depending on the relative refractive index between the sealing layer 125 and one or more refractive image icon focuser arrays 120, the shape of the interface between these two layers may be either convex or concave. For example, as shown in the exemplary embodiment of Figure 1A, if the material forming one or more refractive light-gathering element arrays 120 has a higher refractive index than the material forming the sealing layer 125, the refractive light-gathering elements will have a convex shape. Similarly, if the sealing layer 125 is formed from a material having a higher refractive index than one or more refractive image icon light-gathering element arrays 120, the refractive light-gathering elements will have a concave shape.

[0041] In the non-limiting embodiment shown in Figure 1A, the micro-optical security device 100 is shown to incorporate a sealing layer 125; however, embodiments according to this disclosure are not limited thereto, and embodiments without the sealing layer 125 are also within the scope intended by this disclosure.

[0042] Figure 1B shows the various embodiments of the micro-optical security device 100 of the present disclosure. Several non-limiting embodiments are illustrated. Referring to the non-limiting embodiment in Figure 1B, according to some embodiments, the micro-optical security device 100 includes an unsealed system (e.g., a sealing layer 125 is omitted) in which nanoparticles 117 are incorporated into a matrix used to create an optical spacer 115. According to some embodiments, specific optical properties (e.g., the F-number (F#) and effective focal length of the refractive focus element 121) can be adjusted by adjusting the concentration of nanoparticles 117 in the matrix used to create the optical spacer 115.

[0043] Figure 1C illustrates further embodiments of the micro-optical security device 100 according to various embodiments of the present disclosure. As shown in the non-limiting embodiment of Figure 1C, according to a particular embodiment, the refractive index of the material comprising the sealing layer 125 may be greater than the refractive index of the material comprising one or more refractive image icon focusing element arrays 120. According to a particular embodiment, depending on the relative refractive index of the sealing layer 125, one or more refractive image icon focusing element arrays have a concave or plano-concave lens profile, as shown in Figure 1C.

[0044] Figures 2A to 2D illustrate various embodiments of the present disclosure that allow for adjustment of the optical properties of a refractive image icon focusing element.

[0045] As discussed elsewhere in this disclosure, the design and manufacture of micro-optical security devices often involve negotiating trade-offs between realizing the desired end product and constraints imposed by the laws of physics on the manufacturing materials and selected materials. For example, limited manufacturing tolerances for creating the refractive focuser and image icon layer may limit the precision with which the refractive focuser can properly focus on the image icon. As a further example, manufacturing tolerances may limit the amount of visual information (e.g., details in a single composite image or in multiple different composite images) that can be placed in the focal region beneath the refractive focuser. In systems where the refractive index of the material used to construct the refractive focuser is fixed, the laws of physics dictate that increasing the size of the design space beneath the refractive focuser (e.g., the area of ​​the image icon layer that can provide the image icon and graphic information) requires increasing the thickness of the focuser. In many end products (e.g., banknotes), increasing the thickness of the focuser layer is undesirable because thicker banknotes may be more easily damaged or jammed in processing machines (e.g., banknote receiving slots on vending machines).

[0046] As can be considered with reference to the non-limiting embodiments of Figures 2A to 2D, certain embodiments of the present disclosure enable designers and manufacturers of micro-optical security devices to treat the refractive index of one or more components of the micro-optical security device as an adjustable parameter, thereby reducing the extent to which designers and manufacturers of micro-optical security devices are required to accept a trade-off between one desired performance characteristic (e.g., device thickness) and another desired performance characteristic (e.g., increased visual information under the refractive focus element).

[0047] Referring to non-limiting embodiments in Figures 2A to 2D, a refractive focuser 200 having a height h1 and a width w1 is shown. According to certain embodiments, the refractive focuser 200 is formed from a material comprising at least an organic resin. In some embodiments, the organic resin has a refractive index of less than 1.5. In various embodiments, the refractive index of the refractive focuser can be increased by adding nanoparticles to the polymer matrix used to create the refractive focuser 200.

[0048] According to some embodiments, increasing the refractive index of the refractive condensing element 200 facilitates the realization of one or more desired final product characteristics without trade-offs with other desired final product characteristics. This can be achieved. For example, by adding nanoparticles to increase the refractive index of a refractive light-gathering element, a thinner light-gathering element with the same focal length can be created. For example, refractive light-gathering element 205 has the same width (w1) and focal length as refractive light-gathering element 200, but with a reduced thickness (h2).

[0049] In certain embodiments, increasing the refractive index of the refractive focuser 200 can result in an increase in the available area beneath the refractive focuser, thereby enabling the provision of more visual information beneath the refractive focuser without requiring an increase in the thickness of the focuser or an increase in manufacturing tolerances for encoding visual information (e.g., by creating an array of image icons). For example, a refractive focuser 210 in which nanoparticles are added to the polymer matrix for forming the refractive focuser has a higher refractive index. In this non-limiting embodiment, the refractive focuser 210 has the same thickness and focal length but a larger diameter (w2>w1) than the refractive focuser 200, thereby enabling the encoding of more visual information beneath the refractive focuser 210 than the refractive focuser 200.

[0050] ​In many micro-optical security devices, imperfect focus (i.e., when the focal length of the refractive focuser does not match the depth of the image icon at the target wavelength(s)) corresponds to poor contrast in the composite image provided by the micro-optical security device. According to certain embodiments, the focal length (f) of a refractive focuser 215 having the same width and diameter as the refractive focuser 200 can be adjusted over a length range (Δf) by changing the concentration of nanoparticles in the material mixture used to create the refractive focuser 215. For example, increasing the concentration of nanoparticles in the material mixture corresponds to increasing the refractive index of the refractive focuser 215, thereby decreasing the focal length of the refractive focuser 215. Similarly, decreasing the concentration of nanoparticles in the material mixture corresponds to decreasing the refractive index of the refractive focuser 215, thereby increasing the focal length of the refractive focuser 215.

[0051] The non-limiting embodiments shown in Figures 2A to 2D illustrate the optical tuning of a refractive focuser by adjusting the concentration of nanoparticles in a material mixture, but embodiments according to this disclosure are not limited thereto. The properties of components of a micro-optical security device, such as a sealing layer (e.g., sealing layer 125 in Figure 1A), an optical spacer (e.g., optical spacer 115 in Figure 1A), or a retaining structure for an array of image icons (e.g., retaining structure 114 in Figure 1A), can also be tuned by changing the concentration of nanoparticles in a material mixture to alter the refractive index of the component.

[0052] While the exemplary embodiments shown in Figures 2A to 2D have been described with reference to convex or plano-convex lenses, the embodiments of this disclosure are not limited thereto, and optical tuning using nanoparticles is also possible with multiple lenses of other shapes (e.g., multiple convex lenses or multiple plano-convex lenses).

[0053] Figure 3 illustrates the chromatic aberration associated with light of different wavelengths passing through a refractive image icon focusing element.

[0054] Referring to an exemplary embodiment in Figure 3, a refractive focuser 300 suitable for use in a micro-optical security device (e.g., the micro-optical security device 100 in Figure 1A) is shown. In this exemplary embodiment, the refractive focuser 300 has a refractive index of approximately 1.5. Furthermore, in the embodiment of Figure 3, the refractive index of the refractive focuser 300 can be adjusted to a higher value by adding nanoparticles to the material mixture used to form the refractive focuser 300.

[0055] In this embodiment, the dispersion effect within the refractive condenser 300 causes chromatic aberration, or spherical chromatic aberration, by focusing light of different wavelengths at different focal lengths. For example, a first ray 305 of the color associated with wavelength λ1 passes through the refractive condenser 300 and is focused at a point with focal length f1. Similarly, a second ray 310 of the color associated with a longer wavelength λ2 (e.g., λ2 > λ1) passes through the refractive condenser 300 and is focused at a point with focal length f2, which is longer than focal length f1.

[0056] In the context of micro-optical security devices, the aforementioned chromatic aberration has the effect of reducing the contrast between colors in the composite image produced by the micro-optical system, which may be deemed undesirable by the end product user. Furthermore, as the refractive index of the refractive condenser 300 increases (for example, by adding nanoparticles to the material mixture), the degree of chromatic aberration (e.g., the f2 to f1 ratio) can become more pronounced depending on the change in dispersion within the matrix. In telescopes and cameras, chromatic aberration can be controlled by increasing the overall focal length of the condenser to bring the focal lengths of different wavelengths closer together; however, this approach is generally unacceptable in the context of micro-optical security devices and security documents, where thick products are often unusable. In addition, in certain embodiments, chromatic aberration can be controlled through the introduction of a second lens or a doublet formed from two materials having different dispersion characteristics.

[0057] Figure 4 shows an example of a plurality of image icon arrays located beneath a refractive image icon focusing element, according to several embodiments of the present disclosure. According to certain embodiments of the present disclosure, by using nanoparticles to adjust the refractive index of the refractive focusing element and / or other components of the micro-optical security device, the chromatic aberration effect described with reference to Figure 3 of the present disclosure can be reduced, and the chromatic aberration effect can be utilized to produce a composite image with remarkable visual effects.

[0058] Referring to the exemplary embodiment in Figure 4, the refractive focuser 400 is shown to focus a first ray 405 of a first wavelength λ1 onto a first image icon array 415. According to a particular embodiment, the first image icon array 415 includes one or more features of color associated with wavelengths equal to wavelengths within a specific wavelength range around the first wavelength λ1 (e.g., the colored region 112 in Figure 1). According to a particular embodiment, in addition to the refractive focuser 400, the first ray passes through other optical components of the micro-optical security device (e.g., a spacer layer or a sealing layer), and these components, in combination with the refractive focuser 400, achieve a first effective focal length f1 for light of wavelength λ1. * It has. According to a particular embodiment, f1 * The value can be adjusted by adjusting the concentration of nanoparticles in the refractive light-gathering element 400 and other components of the micro-optical security device.

[0059] As shown in the exemplary embodiment of Figure 4, the refractive focuser 400 is shown to focus a second ray 410 of a second wavelength λ2 onto a second image icon array 420. According to a particular embodiment, the second image icon array 420 includes one or more features of color associated with wavelengths equal to wavelengths within a specified wavelength range around the second wavelength λ2. According to a particular embodiment, in addition to the refractive focuser 400, the first ray passes through other optical components of the micro-optical security device (e.g., a spacer layer or a sealing layer), and these components, in combination with the refractive focuser 400, have a second effective focal length f2 for light of wavelength λ2.* comprising.

[0060] According to some embodiments, the second image icon array 420 is located below the first image icon array 415, such that the second light rays 410 pass through an additional structure 419 (e.g., a spacer layer or a retaining structure) of the micro-optical security device. According to specific embodiments , f2 * the value of may be adjusted, for example, by adjusting the concentration of nanoparticles in the refractive light condensing element 400, similarly to the additional structure 419, to ensure that the second light rays 410 are focused on the second image icon array 420.

[0061] FIG. 5 illustrates aspects of a visual effect in a composite image created by a micro-optical security device, in accordance with a specific embodiment of the present disclosure.

[0062] Referring to the non-limiting example of FIG. 5, the refractive light condensing element 500 has an effective focal length f1 for light of wavelength λ1 * to focus on the first image icon array 515, and is shown to focus a first light ray 505 of a color associated with wavelength λ1 (e.g., blue) through components of the micro-optical security device. Similarly, in this illustrative embodiment, the refractive light condensing element is shown to focus a second light ray 510 of a color associated with a longer wavelength λ2 (e.g., red) through components of the micro-optical security device, including an additional component 519, such that the second light ray has an effective focal length f2 for light of wavelength λ2 * and is focused onto the second image icon array 520.

[0063] Referring to the non-limiting example of FIG. 5, the effective focal length f1 for light of wavelength λ1 * is shorter than the effective focal length f2 for light of wavelength λ2 * . According to various embodiments, the aforementioned f1 * and f2 *The difference in effective focal length between the two represents a wavelength-based difference in F-number. In other words, the features of the first image icon array 515 of the first characteristic color associated with wavelength λ1 form the component of the first characteristic color in the composite image projected by the microoptical system. Similarly, the features of the second image icon array 520 of the second characteristic color associated with wavelength λ2 form the component of the second characteristic color in the composite image projected by the microoptical system.

[0064] Effective focal length f1 for light of wavelength λ1 * and the effective focal length f2 for light of wavelength λ2 * Due to this difference, the image icons associated with the characteristic color of light at wavelength λ1 are formed in the first image icon array 515, which lies on a different layer from the second image icon array 520, which contains image icons associated with the characteristic color of light at wavelength λ2. Assuming all other factors are equal (e.g., both image icon arrays provide similar optical effects), the difference in layer height between the first image icon array 515 and the second image icon array 520 described above means that the components of the composite image created by the micro-optical security of the first characteristic color exhibit a smaller change in position (Δ1) than the change in position (Δ2) of the components of the second characteristic color, depending on the shift in observation position. That is, in the non-limiting embodiment of Figure 5, the red component of the composite image appears to move further and faster than the blue component of the composite image depending on the change in observation position (i.e., Δ2 > Δ1). In other words, the composite image from the first image icon array 515 has a shorter "lever arm" 550 compared to the longer "lever arm" 560 for the long-wavelength components of the composite image from the second image icon array 520. It appears that the image is positioned above the other. Therefore, as the observer adjusts the viewing angle of the micro-optical security device, the long-wavelength components (e.g., red parts) of the composite image on the second image icon array 520 appear to move faster than the short-wavelength components (e.g., blue parts) of the composite image on the first image icon array 515. According to certain embodiments, the relative "velocities" of the different color components of the composite image can be an indicator of the authenticity of the security function.

[0065] The non-limiting embodiments in Figures 3 to 5 illustrate the aspects of optical effects produced by microoptical systems in specific embodiments incorporating lenses depicted as convex or plano-convex lenses, but the embodiments of this disclosure are not limited thereto, and the examples in Figures 3 to 5 are applicable to embodiments using a plurality of lens shapes, including, but not limited to, concave or plano-concave lenses.

[0066] Figures 6A to 6E show various embodiments of the present disclosure, including a micro-encapsulation layer containing nanoparticles. Five embodiments a) to e) of the configuration of an optical security device are shown. Specific embodiments are described with reference to the five embodiments shown in the exemplary embodiments of Figures 6A to 6E, but the disclosure is not limited thereto, and further configurations of micro-optical security devices having nanoparticle-modified encapsulation layers are possible and within the scope assumed by the disclosure.

[0067] Referring to the non-limiting embodiments in Figures 6A to 6E, a particular micro-optical security device according to this disclosure includes a nanoparticle-modulated encapsulation layer 600. In some embodiments, the nanoparticle-modulated encapsulation layer 600 constitutes the topmost layer (relative to the intended observation position) of the micro-optical security device and has a substantially planar top surface to prevent the accumulation of dirt, grease, and other factors that degrade the micro-optical security device's ability to produce composite images. According to various embodiments, the nanoparticle-modulated encapsulation layer 600 is constructed from a material mixture comprising an organic resin (e.g., an acrylate monomer or acrylate oligomer) and one or more nanoparticles, the concentration of which in the material mixture modulates the refractive index of the nanoparticle-modulated encapsulation layer 600. In some embodiments, the concentration of nanoparticles is selected to achieve a predetermined difference in refractive index between the nanoparticle-modulated encapsulation layer 600 and one or more refractive image icon focusing element arrays 605, along a non-planar boundary between the nanoparticle-modulated encapsulation layer 600 and one or more refractive image icon focusing element arrays 605. In the non-limiting embodiments shown in Figures 6A to 6E, the nanoparticle-modified encapsulation layer 600 is constructed of a material having a higher refractive index than the refractive image icon focusing element 605, and as a result, the refractive image icon focusing element 605 has a concave lens shape. Other embodiments of this disclosure are possible and within the intended scope of this disclosure, where the RI difference between the encapsulation layer 600 and the refractive image icon focusing element 605 requires a convex lens shape.

[0068] As illustrated in the exemplary embodiments of Figures 6A to 6E, a micro-optical security device according to a particular embodiment of the present disclosure may include one or more refractive image icon focusing arrays 605. According to a particular embodiment, one or more refractive image icon focusing arrays include a set of structures defining one or more non-planar boundaries between regions of different refractive indices, focusing light of at least one wavelength onto image icons in one or more image icon arrays 615. In some embodiments, the refractive focusing elements in one or more refractive image icon focusing arrays 605 are radially symmetric. In a particular embodiment, the refractive focusing elements are symmetric in the axial or translational direction (e.g., lenticles in a lenticular array). In some embodiments, one or more refractive image icon focusing arrays comprise two or more refractive image icon focusing arrays (e.g., 605a and 605b). In a particular embodiment, the use of multiple refractive image icon focusing arrays may be desirable due to internal reflections, chromatic aberration, or other unwanted visual effects. According to various embodiments, the refractive focusers in one or more refractive image icon focuser arrays 605 have a diameter of 30 μm or more. In various embodiments, the diameter of the refractive image icon focusers 605 is 7.5 to 25 μm.

[0069] In various embodiments of this disclosure, a micro-optical security device having a nanoparticle-adjusted encapsulation layer includes an optical spacer 610. According to some embodiments, the optical spacer 610 may be a sheet of material to which the material for forming other elements of the micro-optical security device is applied and formed. In some embodiments, the optical spacer 610 is integrated with another component of the micro-optical security device (e.g., a refractive image icon focusing element array). In certain embodiments, for example, depending on the difference in refractive index along the non-planar boundary between the encapsulation layer and the refractive image icon focusing element array, the optical spacer 610 plays a role in positioning one or more image icon arrays at the focal length of the refractive image icon focusing element array.

[0070] As shown in the non-limiting embodiments of Figures 6A to 6E, according to certain embodiments of the present disclosure The micro-optical security device includes one or more image icon arrays 615, which are positioned (relative to the intended viewpoint) below one or more refractive image icon focusing element arrays, so that a portion of one or more refractive image icon focusing element arrays 605 projects a composite image of the portions of the one or more image icon arrays 615. According to a particular embodiment, the micro-optical security device has two or more image icon arrays (615a and 615b). In a particular embodiment, each of the image icon arrays includes features having a characteristic color, and each of the image icon arrays is positioned at a depth or location within the micro-optical security device relative to one or more refractive image icon focusing element arrays, so that one or more refractive image icon focusing element arrays are associated with an effective focal length that depends on the wavelength of one or more refractive image icon focusing element arrays 605.

[0071] In various embodiments of this disclosure, a micro-optical security device having a nanoparticle-modified sealing layer further comprises a machine-readable security device (Mr-SD) 620. In certain embodiments, the Mr-SD 620 includes a layer of magnetic ink or another medium, which may be a proprietary device such as a banknote equipment manufacturer's (BEM) machine. When it passes through the device, it provides a characteristic emission or response spectrum against strictly protected verification criteria.

[0072] According to various embodiments, a micro-optical security device having a nanoparticle-modified encapsulation layer 600 has a device thickness of 50 microns or less. As used in this disclosure, the term “device thickness” encompasses the distance from the surface on which light enters the optical device to the surface (opposite to the adhesive layer) that provides the interface between the micro-optical security device and the substrate on which the micro-optical security device is mounted.

[0073] Figures 7A to 7E show five examples a) to e) of configurations of a micro-optical security device without a nanoparticle-modified encapsulation layer, according to various embodiments of the present disclosure. Specific embodiments are described with reference to the five exemplary embodiments shown in Figures 7A to 7E, but the present disclosure is not limited thereto, and further configurations of micro-optical security devices are possible and within the scope assumed by the present disclosure.

[0074] As illustrated in the exemplary embodiments of Figures 7A to 7E, a micro-optical security device according to a particular embodiment of the present disclosure may include one or more refractive image icon focusing arrays 705. According to a particular embodiment, one or more refractive image icon focusing arrays include a set of structures defining one or more non-planar boundaries between regions of different refractive indices, focusing light of at least one wavelength onto image icons in one or more image icon arrays 715. In some embodiments, the refractive focusing elements in one or more refractive image icon focusing arrays 705 are radially symmetric. In a particular embodiment, the refractive focusing elements are axially symmetric (e.g., lenticles in a lenticular array). In some embodiments, one or more refractive image icon focusing arrays comprise two or more refractive image icon focusing arrays (e.g., 705a and 705b). In a particular embodiment, the use of multiple refractive image icon focusing arrays may be desirable due to internal reflections, chromatic aberration, or other unwanted visual effects. According to various embodiments, the refractive focusers in one or more refractive image icon focuser arrays 705 have a diameter of 30 μm or more. According to various embodiments, the refractive focusers are formed from a material mixture comprising an organic resin and nanoparticles, which together have a refractive index greater than 1.5. According to some embodiments, the organic resin in the material mixture has a refractive index of less than 1.5. In certain embodiments, the organic resin in the material mixture has a refractive index of 1.4 or less.

[0075] In various embodiments of this disclosure, a micro-optical security device that omits the nanoparticle preparation encapsulation layer includes an optical spacer 710. According to some embodiments, the optical spacer 710 may be a sheet of material (e.g., a polyester film) to which a material is applied and formed to form other elements of the micro-optical security device. In some embodiments, the optical spacer 710 is integrated with another component of the micro-optical security device (e.g., a refractive image icon focusing element array). In certain embodiments, for example, depending on the difference in refractive index along a non-planar boundary between the refractive image icon focusing element array and another medium (e.g., air), the optical spacer 710 plays a role in positioning one or more image icon arrays at the focal length of the refractive image icon focusing element array.

[0076] As shown in the non-limiting embodiments of Figures 7A to 7E, a micro-optical security device according to a particular embodiment of the present disclosure includes one or more image icon arrays 715, which are positioned (relative to an intended viewpoint) below one or more refractive image icon focusing element arrays, and a portion of one or more refractive image icon focusing element arrays 705 is configured to project a composite image of the portions of the one or more image icon arrays 715. According to a particular embodiment, the micro-optical security device has two or more image icon arrays (715a and 715b). In a particular embodiment, each of the image icon arrays includes a feature having a characteristic color, and each of the image icon arrays is positioned at a depth or location within the micro-optical security device relative to one or more refractive image icon focusing element arrays, and the one or more refractive image icon focusing element arrays are associated with an effective focal length that depends on the wavelength of one or more refractive image icon focusing element arrays 705.

[0077] In various embodiments of this disclosure, a micro-optical security device that does not include a nanoparticle-modified encapsulation layer further comprises a machine-readable security device (Mr-SD) 720. In certain embodiments, the Mr-SD 720 includes a layer of magnetic ink or another medium which provides a characteristic emission or response spectrum to a highly protected verification standard when passing through a proprietary device such as a banknote machine manufacturer's (BEM) machine.

[0078] According to various embodiments, a micro-optical security device without a nanoparticle-based encapsulation layer may have a device thickness of 20 to 30 microns. In some embodiments, a micro-optical security device without a nanoparticle-based encapsulation layer may have a thickness of 20 microns or less. According to a particular embodiment, a micro-optical security device without a nanoparticle-based encapsulation layer may have a device thickness of less than 15 microns.

[0079] Figure 8 shows examples of composite image 800 according to various embodiments of the present disclosure, which include permutations of a first image icon array characteristic color associated with a first characteristic color and a second image icon array characteristic color associated with a second characteristic color.

[0080] Referring to a non-limiting embodiment in Figure 8, a composite image that appears at a first viewing angle, provided by a micro-optical security device (e.g., micro-optical security device 100 in Figure 1), is shown in the figure. According to a particular embodiment, the micro-optical security device projecting the composite image 800 includes a refractive image icon focusing element array tuned with nanoparticles (e.g., refractive image icon focusing element array 120 in Figure 1A), the refractive index of which is tuned to focus light of a first wavelength onto a first layer containing an image icon array associated with a first characteristic color (e.g., image icon array 110b in Figure 1). In this exemplary embodiment, the first characteristic color is blue, but embodiments having a different first characteristic color are possible and within the scope of this disclosure. Similarly, the refractive index of the focusing element of a micro-optical security device providing the composite image shown in Figure 8 can also be tuned to focus light of a second wavelength onto a second layer containing a second image icon array associated with a second characteristic color (e.g., image icon array 110a in Figure 1). In this exemplary embodiment, the second characteristic color is magenta, but embodiments having a different second characteristic color are possible and within the scope of this disclosure. Furthermore, according to some embodiments, a minute light projecting the composite image 800 is used. The image icon layer of the academic security device includes substantially colorless areas between the image icons (e.g., areas of transparent material defining the structure that holds the image icons).

[0081] As shown in Figure 8, the composite image 800 provided at the first viewing angle includes shades, or permutations, made from a first characteristic color, a second characteristic color, and colorless areas. For example, composite image 800 includes area 801, which is blue with the same hue as the first characteristic color. Similarly, composite image 800 includes area 803, which is blue with a lighter hue than the first characteristic color. Furthermore, composite image 800 includes area 805, which is magenta with the same hue as the second characteristic color. Furthermore, composite image 800 includes area 807, which is magenta with a lighter hue than the second characteristic color. Furthermore, composite image 800 includes area 809, which is substantially colorless, as is the case with certain gap areas within the image icon layer. In addition, composite image 800 includes area 811, which is shades of purple associated with a mixed color of the first and second characteristic colors. As shown in the non-limiting embodiment of Figure 8, the composite image 800 includes region 813, which is a shade of purple associated with a second characteristic color and a lighter shade of blue of the first characteristic color (e.g., a lighter shade of blue in region 803). Similarly, the composite image 800 includes region 815, which is a shade of purple associated with a lighter shade of blue of the first characteristic color and a lighter shade of magenta of the second characteristic color (e.g., a lighter shade of magenta in region 807). Finally, in a particular embodiment, the composite image 800 includes region 817, which is a shade of purple associated with a first characteristic color and a lighter shade of magenta of the second characteristic color (e.g., a lighter shade of magenta in region 807).

[0082] Accordingly, certain embodiments of the present disclosure provide the unexpected result that, by employing a two-color icon structure, a single light-gathering element can provide at least nine colors to a composite image provided by a microoptical system including the icon structure and the light-gathering element. More generally, in certain embodiments of the present disclosure, the composite image provided by the security device over a first viewing angle range can include at least nine colors by adjusting the positions of image icons associated with a first characteristic color and image icons associated with a second characteristic color within two image icon layers.

[0083] In addition, in certain embodiments, further colors beyond at least nine provided by a single focusing element projecting light from two or more layers of image icon structures can be achieved by aggregating the outputs of multiple focusing elements whose color outputs are modulated according to various embodiments of the Disclosure. As a non-limiting embodiment, consider an area of ​​a micro-optical security device (e.g., a micro-optical security device) containing 100 micro-optical cells, where each micro-optical cell can output at least nine colors by adjusting the position and presence of image icons in two layers of the image icon structure. In this context, the term "micro-optic cell" encompasses the three-dimensional portion of a micro-optic security device corresponding to a single light-gathering element, as shown in Figure 4 of this disclosure. By configuring a first portion (e.g., one-third) of the micro-optic cell to output one of at least nine colors achievable with two layers of an icon structure (e.g., a brighter shade of magenta in region 807 of Figure 8), and a second portion of the micro-optic cell to output another color from the at least nine colors (e.g., magenta shown in region 805 of Figure 8), the 100 micro-optic cell regions appear as color regions that are a mixture of the colors output by the first and second portions of the micro-optic cell within that region. Thus, according to certain embodiments, by scattering cells that output different colors from the at least nine colors output by each micro-optic cell, it becomes possible to control the colors provided by the micro-optic security system with extreme precision.

[0084] Figures 9A, 9B, and 9C illustrate an embodiment for generating a composite image that includes a combination of a characteristic color of a first image icon array associated with a first characteristic color and a characteristic color of a second image icon array associated with a second characteristic color.

[0085] Referring to the non-limiting embodiments in Figures 9A, 9B, and 9C, in certain embodiments, the combination of characteristic color sets for image icons can be achieved by adjusting the position of the image icons relative to the focal positions of the image icons and colorless areas within the image icon layer.

[0086] Referring to a non-limiting embodiment in Figure 9A, a first subsection 900 of a micro-optical security device (e.g., micro-optical security device 100 in Figure 1) is shown. According to a particular embodiment, the micro-optical security device includes a sealing layer 901 (e.g., sealing layer 125 in Figure 1), a plurality of light-gathering elements including light-gathering elements 903, 905, and 907, and an optical spacer 913 (e.g., optical spacer 115 in Figure 1). In some embodiments of the present disclosure, one or more of the sealing layer 901, light-gathering elements 903, 905, and 907, or optical spacer 913 are constructed from a polymer matrix containing nanoparticles to adjust the refractive index of the layer. Furthermore, in some embodiments of this disclosure, depending on the lens shape selected for the light-gathering elements 903, 905, and 907 (e.g., a convex or concave lens), the sealing layer 901 or one or more of the light-gathering elements 903, 905, and 907 is constructed from a low-RI material, for example, a material having an RI of less than 1.4, a material having an RI between 1.30 and 1.35, or a material having an RI of less than 1.3. In certain embodiments, one or more of the sealing layer 901, the light-gathering elements 903, 905, and 907, or the optical spacer 913 is constructed from a polymer matrix that does not contain nanoparticles to adjust the refractive index of the layer.

[0087] As shown in the exemplary embodiment of Figure 9A, the micro-optical security device further comprises a first image icon array associated with a first characteristic color (in this exemplary embodiment, blue, but other colors are possible and within the intended scope of the Disclosure) disposed within a first layer 909. Furthermore, in some embodiments of the Disclosure, the micro-optical security device comprises a second image icon array associated with a second characteristic color (in this exemplary embodiment, magenta, but other colors are possible and within the intended scope of the Disclosure). According to a particular embodiment, the space between the image icons of the first layer 909 and the second layer 911 comprises a substantially colorless material (e.g., a polymer that does not contain coloring pigments).

[0088] According to a particular embodiment, at a first field of view, each of the light-gathering elements 903, 905, and 907 focuses light incident on the micro-optical security device along paths converging at foci 915, 917, and 919, respectively, into regions within the first layer 909 and the second layer 911. Similarly, light exits the micro-optical security device from foci 915, 917, and 919 along the same paths shown in the figure. As described elsewhere in this disclosure, by subtly adjusting the position of the colored pigment-containing image icons with respect to the paths taken by the light arriving at the micro-optical security device in the direction associated with the first field of view for each of the foci 915, 917, and 919 (referred to herein as “focus paths”), the arrangement of colors provided to the composite image provided by the micro-optical system is altered beyond the two characteristic colors used for the image icons in the first layer 909 and the second layer 911. It is possible.

[0089] In a first embodiment, when the image icon 921a associated with a first characteristic color and the image icon 921b associated with a second characteristic color are both on the same focal path of the light-gathering element, the components of the composite image provided by the light-gathering element 903 have a color that is a mixture of the first and second characteristic colors. In this non-limiting embodiment, the first characteristic color (blue) is the second By mixing it with the characteristic color (magenta), it produces a deep purple color, 923.

[0090] In a second embodiment, when the image icon 925a associated with the first characteristic color is offset from the focal path of the light-gathering element, and the image icon 925b associated with the second characteristic color is on the focal path, the components of the composite image provided by the light-gathering element 905 have a color that is a mixture of the first characteristic color, a colorless region, and the second characteristic color. In this non-limiting embodiment, offsetting the image icon 925a relative to the focal path generates a color 927 which is a purplish-pinkish hue. In this non-limiting embodiment, the contribution of the first characteristic color to color 927 is mainly diluted by the offset of the image icon 925a from the focal path, but the contribution of the second characteristic color is substantially unaffected.

[0091] In a third embodiment, when an image icon 929a associated with a first characteristic color is positioned on the focal path of the condensing element, and an image icon 929b associated with a second characteristic color is offset from the focal path of the condensing element, the components of the composite image provided by the condensing element 907 have a color 931 which is a mixture of the first characteristic color, the second characteristic color, and the substantially colorless region between the image icons of the second layer 911. In this particular embodiment, the color 931 includes a bluish-purple hue. In this exemplary embodiment, the contribution of the first characteristic color is substantially unaffected, but the contribution of the second characteristic color to color 931 is diluted by the offset of the image icon 929b from the focal path.

[0092] Figure 9B provides further explanatory examples of achieving a limited set of combinations of characteristic colors in a composite image according to various embodiments of the present disclosure.

[0093] Referring to a non-limiting embodiment in Figure 9B, a second subsection 991 of the micro-optical device is shown in Figure 9B. For convenience of reference, the second subsection 991 utilizes the same structure as the first subsection 900 shown in Figure 9A. As shown in this exemplary embodiment, the second subsection 991 includes a sealing layer 901, light-gathering elements 903, 905, and 907, and an optical spacer 913, which are equivalent in structure to their corresponding embodiments described with reference to Figure 9A. Similarly, the second subsection 991 includes a first layer 909 and a second layer 911, which are equivalent to their corresponding embodiments in Figure 9A.

[0094] According to a particular embodiment, by offsetting the image icon 933 associated with the first characteristic color from the focal path of the light-gathering element and not providing an image icon in the second layer 911, the components of the composite image provided by the light-gathering element 903 have a color 935 which is a combination of the first characteristic color and a substantially colorless material in the first layer 909. In this particular embodiment, the color 935 is a lighter shade of the first characteristic color, and in this embodiment, includes a lighter shade of blue.

[0095] In some embodiments of this disclosure, by omitting image icons close to the focal path of the light-gathering element 905 and offsetting image icons 937 from the focal path, the components of the composite image provided by the light-gathering element 905 have a color 939 which is a combination of a second characteristic color and a substantially colorless material in the second layer 911. In this non-limiting embodiment, the color 939 is a lighter shade of the second characteristic color, and in this exemplary embodiment, this includes a lighter shade of pink.

[0096] In various embodiments of this disclosure, by offsetting both image icons 941 and 941b associated with a first characteristic color from the path of the light-gathering element 907, the components of the composite image provided by the light-gathering element 907 are the first characteristic color, the second characteristic color, and the color which is a combination of substantially colorless materials in the first layer 909 and the second layer 911. It has 943. In this non-limiting embodiment, color 943 includes lavender.

[0097] Referring to a non-limiting embodiment in Figure 9C, a third subsection 993 of the micro-optical device is shown in Figure 9C. For convenience of reference, the third subsection 993 utilizes the same structure as the first subsection 900 shown in Figure 9A. As shown in this exemplary embodiment, the third subsection 993 includes a sealing layer 901, light-gathering elements 903, 905, and 907, and an optical spacer 913, which are equivalent in structure to the corresponding embodiments described with reference to Figure 9A. Similarly, the third subsection 993 includes a first layer 909 and a second layer 911, which are equivalent to their corresponding embodiments in Figure 9A.

[0098] Referring to a non-limiting embodiment in Figure 9C, according to a particular embodiment, by positioning the image icon 945 associated with the first characteristic color on the focal path of the light-gathering element 903, and not positioning the image icon associated with the second characteristic color on or near the focal path of the light-gathering element 903, the color 947 of the component of the composite image partially projected by the light-gathering element 903 is the first characteristic color.

[0099] According to various embodiments, the color 951 contributing to the composite image of the light-gathering element 905 is the second characteristic color, provided that the image icon 949 associated with the second characteristic color is positioned on the focal path of the light-gathering element 905, and the image icon associated with the first characteristic color is not positioned on or near the focal path of the light-gathering element 905.

[0100] Similarly, in various embodiments of this disclosure, by not positioning the colored image icons on or near the focal path of the light-gathering element 907, the contribution of the light-gathering element 907 to the composite image is substantially colorless, as is the region between the image icons of the first layer 909 and the second layer 911.

[0101] In the embodiments of Figures 8 and 9A–9C, modulation between combinations of characteristic colors has been described with reference to a microoptical system using refractive focusing elements, but embodiments of the present disclosure are not limited thereto, and the color modulation effect described above can also be generated in systems using reflective focusing elements (e.g., the microoptical security device 100 in Figure 1C). Additionally, certain embodiments of the present disclosure describe achieving microoptical cell-level modulation of the colors that a cell provides to a composite image with reference to a system having a two-layer image icon structure and image icons associated with two characteristic colors, but the present disclosure is not limited thereto. Embodiments including image icon structures having more than two layers, and embodiments having image icons associated with three or more characteristic colors are within the intended scope of the present disclosure.

[0102] According to certain embodiments, further granularity of micro-level colors output by a finite set of characteristic colors for icon elements can be achieved by adjusting the size of the image icons associated with each characteristic color. Where used in this disclosure, the term “micro-level” encompasses the colors observed through a single focusing element in the absence of a colored substrate. According to some embodiments, the size of the image icons associated with a particular characteristic color can be adjusted by one or more of the following: changing the line width of line icons, removing partial image icons, or doubling the size of the image icons within the footprint of the image icon focusing element.

[0103] In some embodiments of this disclosure, further granularity of color at the macro level may be on the boundary between whether an image icon is within the focal path of the image icon focusing element and whether it is within the focal path of the image icon focusing element, in response to subtle variations in the viewing angle, so as to produce regions showing intermediate colors between colors associated with a combination of the first and second characteristic colors. It can become larger. Where used in this disclosure, the term “macro level” encompasses the colors observed when multiple micro-optical cells are viewed simultaneously. Region 819 in Figure 8 provides a non-limiting embodiment of macro-level granularity in the colors observed when multiple micro-optical cells of a micro-optical security device are viewed simultaneously. As shown in Figure 8, in region 819, a visible color gradient (not a sharp boundary) can be observed between two hues, containing multiple shades of the characteristic color.

[0104] Figures 10A and 10B show examples of a micro-optical security device according to a particular embodiment of the present disclosure.

[0105] Referring to a non-limiting embodiment in Figure 10A, an example of a micro-optical device 1000 is illustrated. According to a particular embodiment, the micro-optical device 1000 includes a sealing layer 1005, a refractive focuser array 1010, an optical spacer 1015, and an image icon layer 1020 containing a plurality of image icons 1025.

[0106] According to a particular embodiment, the micro-optical device 1000 comprises a device capable of projecting various composite images, the projected composite images including, but not limited to, color shift effects, optically variable effects, and compositely enlarged images of content within an image icon layer 1020 visible above and / or below the plane of the micro-optical device 1000. As shown in the exemplary embodiment of Figure 10A, the encapsulation layer 1005 is formed from a material having a higher refractive index than the material used to form the refractive focuser array 1010. In some embodiments, the encapsulation layer 1005 is formed from a high refractive index material such as an acrylate having aromatic functional groups with dispersed nanozirconia nanoparticles. In one non-limiting embodiment, the encapsulation layer 1005 has a refractive index of about 1.6 in a particular embodiment, and the encapsulation layer 1005 is formed as a UV-curable layer comprising a liquid blend of zirconium dioxide acrylate monomer mixture, a blend of bisphenol full orange acrylate and O-phenylphenol ethyl acrylate, and a suitable photoinitiator.

[0107] According to various embodiments, the refractive index focusing element array 1010 is formed from a material having a refractive index of 1.5 or less. Applying the lens maker's equation, the overall thickness of the micro-optical device 1000 can be reduced for a given lens radius by increasing the difference in refractive index between the material forming the sealing layer 1005 and the material constituting the refractive index focusing element array 1010. In some embodiments, the difference in refractive index between the two materials is greater than 0.1. In certain embodiments, the difference in refractive index between the material used to form the sealing layer 1005 and the refractive index focusing element array 1010 is 0.1 to 0.15, and in some embodiments, the difference in refractive index is 0.16 to 0.20. In various embodiments, the difference in refractive index is 0.21 to 0.25, and in some embodiments, the difference in refractive index is 0.26 or greater.

[0108] As an exemplary embodiment, in at least one embodiment, the refractive focuser array 1010 is formed from a layer of UV-curable fluorinated acrylic material blend having a refractive index of about 1.35, for example, a mixture comprising one or more fluorourethane acrylates and a suitable photoinitiator. Fluorinated acrylic materials offer certain manufacturing advantages, including, but not limited to, low tackiness, good adhesion to other acrylic materials, soil and chemical resistance, and a glass transition temperature high enough to avoid deformation or excessive tackiness of the layer during manufacturing. Further examples of materials suitable for the refractive focuser array include, but are not limited to, silicone acrylates and silicone methacrylates.

[0109] As shown in the non-limiting embodiment of Figure 10A, the micro-optical device 1000 includes an optical spacer 1015 (e.g., optical spacer 115 in Figure 1A). According to a particular embodiment, the optical spacer 1015 is formed from a substantially transparent film with a thin cross-section, such as 75-gauge polyethylene terephthalate (PET). According to various embodiments, the micro-optical device 1000 includes an image icon layer 1020 (e.g., image icon layer 615 in Figures 6A-6E). In a particular embodiment, the image icon layer 615 includes a set of cast and cured retaining structures, which are then filled with a UV-curable material of one or more characteristic colors, and the UV-curable material is cured to form a plurality of image icons (e.g., image icon 1025).

[0110] A skilled technician would understand that the overall thickness of an embodiment of the micro-optical device 1000 may depend on a set of application-specific variables, including the visual effect produced by the system, the desired lens size, and the number of image icon layers. However, the difference in refractive index between the sealing layer and the focusing element allows for an overall thickness of approximately 30 microns in a device having a fully sealed spherical lens that can project a composite image with various optical effects (including, but not limited to, color changes, multidirectional effects, or motion effects due to orthoparallax) on a single image icon layer.

[0111] In the exemplary embodiment shown in Figure 10A, the micro-optical security device 1000 has been described with reference to a configuration in which the sealing layer 1005 is made of a material having a higher refractive index than the refractive focus element array 1010, but embodiments according to this disclosure are not limited thereto.

[0112] Figure 10B shows an example of a micro-optical security device 1050 in which the relative positions of high-RI material and low-RI material are reversed in the sealing layer 1005 and the refractive light-gathering element array 1010. For the convenience of cross-referencing, the structural elements of the micro-optical security device 1050 that are common to the micro-optical security device 1000 in Figure 10A are given the same numbering.

[0113] In some embodiments, the difference in refractive index between the sealing layer and the focusing element can be reversed so that the sealing layer is formed from a low-RI material. In such embodiments, the shape of the focusing element also switches from a concave lens to a convex lens, as shown in Figure 10B. In addition, in certain embodiments, the refractive focusing element array 1010 includes a transition region 1030 between the curved (i.e., concave or convex) lens surface of the focusing element and the optical spacer 1015. According to certain embodiments, the presence of the transition region 1030, which ensures a minimum thickness through the refractive focusing element array 1010, reduces the possibility of individual focusing elements of the refractive focusing element array 1010 "popping off" or otherwise separating from the whole system. This improves the structural integrity of the micro-optical system 1050.

[0114] Similarly, while the exemplary embodiment of the micro-optical device 1000 in Figure 10A has been described with reference to an embodiment having a single-layer icon structure, the embodiments of this disclosure are not limited thereto. In certain embodiments, the micro-optical device has a multilayer icon structure (for example, as shown with reference to Figures 9A–9C of this specification).

[0115] An embodiment of a security device according to a particular embodiment of the present disclosure is a security device comprising one or more image icon arrays, one or more refractive image icon focusing element arrays, and a sealing layer, wherein one or more refractive image icon focusing element arrays are arranged on one or more image icon arrays such that a portion of the one or more refractive image icon focusing element arrays projects a composite image of the portions of the one or more image icon arrays, and the one or more refractive image icon focusing element arrays are in contact with the sealing layer along a non-planar boundary.

[0116] An example of a security device according to a particular embodiment of the present disclosure includes a security device in which at least one of one or more refractive image icon focusing element arrays and a sealing layer comprises a mixture of an organic resin having a first refractive index and nanoparticles.

[0117] Examples of security devices according to some embodiments of the present disclosure include a security device in which at least one of a refractive image icon focusing element array and a sealing layer comprises a low refractive index material having a second refractive index, and the difference between the first refractive index and the second refractive index is 0.1 or greater.

[0118] Examples of security devices according to some embodiments of the present disclosure include security devices in which the low refractive index material has a refractive index between 1.3 and 1.4.

[0119] Examples of security devices according to some embodiments of the present disclosure include security devices in which the low refractive index material has a refractive index of less than 1.3.

[0120] Examples of security devices according to some embodiments of the present disclosure include security devices in which the low refractive index material comprises a fluorinated acrylate or a fluorinated urethane acrylate.

[0121] Examples of security devices according to some embodiments of the present disclosure include security devices in which the low refractive index material comprises a perfluoropolyether compound.

[0122] Examples of security devices according to some embodiments of the present disclosure include a security device in which the mixture of nanoparticles comprises one or more nanoparticles of aluminum oxide, zirconium dioxide, titanium dioxide, zinc sulfide, or zinc telluride.

[0123] Examples of security devices according to various embodiments of this disclosure include security devices in which the organic resin comprises an acrylate monomer.

[0124] Examples of security devices according to various embodiments of this disclosure include security devices in which the organic resin comprises an acrylate oligomer.

[0125] Examples of security devices according to certain embodiments of the present disclosure include a security device in which the organic resin comprises one or more of the following: phenoxybenzyl acrylate, O-phenylphenoxyethyl acrylate, phenylthioethyl acrylate, bis-phenylthioethyl acrylate, cumin phenoxyethyl acrylate, biphenylmethyl acrylate, bisphenol A epoxy acrylate, fluorene-type acrylate, brominated acrylate, halogenated acrylate, or melamine acrylate.

[0126] Examples of security devices according to certain embodiments of the present disclosure include security devices in which the organic resin comprises one or more of isodecyl acrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polyester tetraacrylate, trimethylolpropane triacrylate, or hexanediol diacrylate.

[0127] Examples of security devices according to certain embodiments of this disclosure include security devices in which the organic resin does not contain polarizing elements.

[0128] Examples of security devices according to certain embodiments of this disclosure do not include a sealing layer. Includes security devices.

[0129] Examples of security devices according to some embodiments of the present disclosure include security devices in which the sealing layer has a refractive index of 1.5 or higher.

[0130] Examples of security devices according to various embodiments of this disclosure include security devices in which the sealing layer has a refractive index of 1.6 or higher.

[0131] Examples of security devices according to various embodiments of the present disclosure include a security device in which a refractive image icon focusing element array includes a transition region between the lens surface and a spacer layer of the refractive image icon focusing element array.

[0132] Examples of security devices according to various embodiments of the present disclosure include security devices in which the refractive image icon focusing elements in one or more refractive image icon focusing element arrays have a diameter greater than 30 microns.

[0133] Examples of security devices according to various embodiments of the present disclosure include security devices in which the refractive image icon focusing elements in one or more refractive image icon focusing element arrays have a diameter of less than 30 microns.

[0134] An embodiment of a security device according to a particular embodiment of the present disclosure includes a security device comprising a refractive image icon focusing element array and a spacer layer disposed between the image icon array, wherein the spacer layer comprises nanoparticles.

[0135] Examples of security devices according to some embodiments of the present disclosure include a security device comprising a spacer layer integrated with a refractive image icon focusing element array.

[0136] Examples of security devices according to various embodiments of the present disclosure include security devices comprising two or more refractive image icon focusing element arrays that contact one or more non-planar boundaries.

[0137] Examples of security devices according to some embodiments of the present disclosure include security devices having a thickness of 50 microns or less.

[0138] An example of a security device according to a particular embodiment of the present disclosure includes a security device having a thickness of 20 microns or less.

[0139] Examples of security devices according to various embodiments of this disclosure include security devices having a thickness of 15 microns or less.

[0140] Examples of security devices according to some embodiments of the present disclosure include a security device comprising a machine-readable security device (Mr-SD).

[0141] An embodiment of a security device according to a particular embodiment of the present disclosure includes a security device comprising two or more image icon arrays, each of which includes a feature having a characteristic color associated with the image icon array, each of which is disposed at a depth relative to one or more refractive image icon focusing element arrays associated with a wavelength-dependent focal length, wherein the wavelength-dependent focal length is associated with the characteristic color associated with the image icon array.

[0142] Examples of security devices according to various embodiments of the present disclosure include security devices in which a composite image includes shades of one or more characteristic colors moving at different speeds.

[0143] Embodiments of security devices according to some embodiments of the present disclosure include a security device comprising one or more image icon arrays and one or more refractive image icon focusing element arrays, wherein one or more refractive image icon focusing element arrays comprise a mixture of an organic resin and nanoparticles, the one or more refractive image icon focusing element arrays are arranged on one or more image icon arrays so that a portion of the one or more refractive image icon focusing element arrays projects a composite image of a portion of the one or more image icon arrays, and the mixture of the organic resin and nanoparticles has a refractive index greater than 1.5.

[0144] Examples of security devices according to certain embodiments of the present disclosure include security devices in which the organic resin has a refractive index of less than 1.5.

[0145] Examples of security devices according to various embodiments of this disclosure include security devices in which the mixture of organic resin and nanoparticles has a refractive index greater than 1.6.

[0146] Examples of security devices according to some embodiments of the present disclosure include security devices in which a mixture of an organic resin and nanoparticles has a refractive index greater than 1.7.

[0147] An example of a security document according to a particular embodiment of the present disclosure includes a substrate attached to one or more security devices according to an embodiment of the present disclosure.

[0148] Examples of security devices according to various embodiments of the present disclosure include a security device in which the composite image comprises a region of third color, the third color comprising at least one combination (permutation) of a first characteristic color or a second characteristic color.

[0149] An embodiment of a security device according to a particular embodiment of the present disclosure includes a security device in which the composite image provided by the security device over a first range of viewing angles includes at least nine colors, the at least nine colors including a combination (permutation) of a first characteristic color and a second characteristic color.

[0150] Embodiments of security devices according to various embodiments of the present disclosure include a security device in which each image icon focusing element of an image icon focusing element array comprises an image icon focusing element associated with a focal path, and an image icon layer comprising one or more regions between the image icons comprising one or more image icons associated with a first characteristic color, one or more image icons associated with a second characteristic color, and a certain volume of substantially colorless material, wherein, for a given viewing angle, the color is visible through each image icon focusing element, and the color visible through each image icon focusing element at a first viewing angle is based on one or more of the first characteristic color, the second characteristic color, or substantially colorless material.

[0151] Embodiments of security devices according to some embodiments of the present disclosure include a security device in which, in the absence of a colored substrate, when there are no image icons positioned on the focal path of the image icon focusing element or offset from the focal path, the color visible through the image icon focusing element at a first viewing angle is white, associated with a certain volume of substantially colorless material.

[0152] An embodiment of a security device according to a particular embodiment of the present disclosure is such that, in the absence of a colored substrate, the image icon associated with a first characteristic color is offset from the focal path of the image icon focusing element in a first viewing angle. The security device includes a color visible through which a component is associated with a bright hue of a first characteristic color, and in the absence of a colored substrate, when an image icon associated with a second characteristic color is offset from the focal path of the image icon focusing element, the color visible through the image icon focusing element at a first viewing angle is associated with a component associated with a bright hue of the second characteristic color.

[0153] An embodiment of a security device according to a particular embodiment of the present disclosure, wherein, in the absence of a colored substrate, the colors visible through the image icon focusing element include combinations from a group of nine combinations of the first characteristic color and the second characteristic color, and the group of nine combinations is A first color (947) associated with an image icon associated with a first characteristic color disposed in the focal path of the image icon condenser, and the absence of an image icon associated with a second characteristic color disposed in or offset from the focal path of the image icon condenser; a second color (951) associated with an image icon associated with a second characteristic color disposed in the focal path of the image icon condenser, and the absence of an image icon associated with a first characteristic color disposed in or offset from the focal path of the image icon condenser; a third color including white associated with a substantially colorless material associated with the absence of any image icon disposed in or offset from the focal path of the image icon condenser; a fourth color (935) associated with an image icon associated with a first characteristic color offset from the focal path of the image icon condenser, and the absence of an image icon associated with a second characteristic color disposed in or offset from the focal path of the image icon condenser; and an image icon associated with a second characteristic color offset from the focal path of the image icon condenser. The absence of an image icon associated with a first characteristic color disposed in or offset from the focal path of the image icon condenser, and a fifth color (939) associated with it, and an image icon associated with a first characteristic color disposed in or offset from the focal path of the image icon condenser, and an image icon associated with a second characteristic color disposed in or offset from the focal path of the image icon condenser, and a sixth color (923) associated with it, and an image icon associated with a first characteristic color disposed in or offset from the focal path of the image icon condenser, and an image icon associated with a second characteristic color offset from the focal path of the image icon condenser, and a seventh color (931) associated with it, and an image icon associated with a second characteristic color disposed in or offset from the focal path of the image icon condenser, and an eighth color (927) associated with it, and an image icon associated with a first characteristic color offset from the focal path of the image icon condenser, and an image icon associated with a first characteristic color offset from the focal path of the image icon condenser,Includes a security device, which includes the ninth color (943) associated with it. An embodiment of a security device according to a particular embodiment of the present disclosure includes a security device comprising a first image icon associated with a first characteristic color and a second image icon associated with a second characteristic color, wherein, in the absence of a colored substrate, the ratio of the size of the first image icon to the size of the second image icon is such that the color visible through the image icon focusing element includes a tenth color that is not one of the nine combinations of the first and second characteristic colors.

[0154] Examples of security devices according to some embodiments of the present disclosure include a security device comprising one or more refractive image icon focusing elements or reflective image icon focusing elements.

[0155] Examples of security devices according to various embodiments of the present disclosure include security devices in which the image icon focusing element comprises a mixture of an organic resin and nanoparticles.

[0156] Examples of security documents according to various embodiments of the present disclosure include security documents comprising a substrate and a security device mounted on the substrate. In some embodiments, the security device includes one or more image icon arrays, one or more refractive image icon focusing element arrays, and a sealing layer comprising an organic resin and nanoparticles. In some embodiments, one or more refractive image icon focusing element arrays are arranged on one or more image icon arrays such that a portion of one or more refractive image icon focusing element arrays forms a composite image of a portion of one or more image icon arrays. In some embodiments, one or more refractive image icon focusing element arrays are in contact with the sealing layer along a non-planar boundary.

[0157] Examples of security documents according to various embodiments of the present disclosure include security documents comprising a substrate and a security device mounted on the substrate. In some embodiments, the security device includes one or more image icon arrays and one or more refractive image icon focusing element arrays, the one or more refractive image icon focusing element arrays comprising a mixture of an organic resin and nanoparticles. In certain embodiments, the one or more refractive image icon focusing element arrays are arranged on one or more image icon arrays such that a portion of the one or more refractive image icon focusing element arrays forms a composite image of a portion of the one or more image icon arrays. In some embodiments, the mixture of an organic resin and nanoparticles has a refractive index greater than 1.5.

[0158] An embodiment of a security document according to a particular embodiment of the present disclosure includes a security document comprising a substrate and a security device mounted on the substrate. In some embodiments, the security device comprises one or more image icon arrays, one or more refractive image icon focusing element arrays, and a spacer layer disposed between one or more image icon arrays, the spacer layer comprising a mixture of an organic resin and nanoparticles. In certain embodiments, one or more refractive image icon focusing element arrays are disposed on one or more image icon arrays such that a portion of one or more refractive image icon focusing element arrays forms a composite image of a portion of one or more image icon arrays. In some embodiments, the mixture of the organic resin and nanoparticles has a refractive index greater than 1.5.

[0159] Nothing in the description in this application should be construed as implying that any particular element, step, or function is an essential element that must be included in the claims. The scope of the patented subject matter is defined solely by the claims. Furthermore, none of the claims contain a participle following the exact word "means for". Unless the following conditions are met, I do not intend to invoke Section 112(f) of the U.S. Patent Act.

Claims

1. Security devices (100, 600, 700, 1000, 1050), A refractive image icon focusing element array (120, 605, 705, 1010) wherein each refractive image icon focusing element of the refractive image icon focusing element array is associated with a focal path, A first image icon layer comprising one or more image icons (110a, 909) associated with a first characteristic color, A second image icon layer is located below the first image icon layer and comprises one or more image icons (110b, 911) associated with a second characteristic color, It comprises a sealing layer (125, 600, 1005), The sealing layer and at least one of the array of one or more refractive image icon light-gathering elements contain an organic resin mixture having a first refractive index. At least one of the refractive image icon light-gathering element array and / or the sealing layer includes a low refractive index material having a second refractive index lower than the first refractive index. In the first viewing angle, the color is visible through each image icon light-gathering element. When the image icon (925a) associated with the first characteristic color is offset from the focal path of the image icon focusing element, the color visible through the image icon focusing element at the first viewing angle has the same hue as the first characteristic color and has a component associated with a hue that is brighter than the first characteristic color. When the image icon (929b) associated with the second characteristic color is offset from the focal path of the image icon focusing element, the color visible through the image icon focusing element at the first viewing angle has the same hue as the second characteristic color and has a component associated with a hue that is brighter than the second characteristic color. Security device.

2. At least one of the refractive image icon light-gathering element array and the sealing layer includes the low refractive index material, and the low refractive index material has the second refractive index. The difference between the first refractive index and the second refractive index is greater than or equal to 0.

1. The security device according to claim 1.

3. The security device according to claim 2, wherein the low refractive index material has a refractive index between 1.3 and 1.

4.

4. The security device according to claim 2, wherein the low refractive index material has a refractive index of less than 1.

3.

5. The security device according to claim 2, wherein the low refractive index material includes a fluorinated acrylate or a fluorinated urethane acrylate.

6. The security device according to claim 2, wherein the low refractive index material comprises a perfluoropolyether compound.

7. The security device according to claim 1, wherein the organic resin mixture having the first refractive index comprises one or more nanoparticles of aluminum oxide, zirconium dioxide, titanium dioxide, zinc sulfide, or zinc telluride.

8. The security device according to claim 1, wherein the organic resin mixture comprises an acrylate monomer.

9. The security device according to claim 1, wherein the organic resin mixture comprises an acrylate oligomer.

10. The image further comprises one or more regions between image icons containing a certain volume of substantially colorless material, The security device according to claim 1, wherein the color visible through each image icon light-gathering element at the first viewing angle is based on a combination of two or more of the first characteristic color, the second characteristic color, and the substantially colorless material.

11. The security device according to claim 10, wherein, in the region corresponding to the image icon light-gathering element, when no image icons are placed in either the first image icon layer or the second image icon layer, the color visible through the image icon light-gathering element at the first viewing angle is white, associated with a certain volume of substantially colorless material.

12. The colors visible through the image icon light-gathering element at the first viewing angle include a group of nine colors resulting from a combination of the first characteristic color, the second characteristic color, and the contribution of the substantially colorless material, and the group of nine colors is A first color (947) based on the fact that an image icon associated with the first characteristic color is disposed in the focal path of the image icon focusing element, and that no image icon associated with the second characteristic color is disposed in the region corresponding to the image icon focusing element, A second color (951) based on the fact that an image icon associated with the second characteristic color is disposed in the focal path of the image icon focusing element, and that no image icon associated with the first characteristic color is disposed in the region corresponding to the image icon focusing element, A third color, including white, associated with the substantially colorless material, based on the fact that no image icons are placed in either the first image icon layer or the second image icon layer in the region corresponding to the image icon light-gathering element, A fourth color (935) based on the fact that an image icon associated with the first characteristic color is offset from the focal path of the image icon focusing element, and that no image icon associated with the second characteristic color is placed in the region corresponding to the image icon focusing element, A fifth color (939) based on the fact that an image icon associated with the second characteristic color is offset from the focal path of the image icon focusing element, and that no image icon associated with the first characteristic color is placed in the region corresponding to the image icon focusing element, A sixth color (923) based on an image icon associated with the first characteristic color disposed in the focal path of the image icon light-gathering element, and an image icon associated with the second characteristic color disposed in the focal path of the image icon light-gathering element, A seventh color (931) based on an image icon associated with the first characteristic color disposed in the focal path of the image icon focusing element, and an image icon associated with the second characteristic color offset from the focal path of the image icon focusing element, An eighth color (927) based on an image icon associated with the second characteristic color disposed in the focal path of the image icon focusing element, and an image icon associated with the first characteristic color offset from the focal path of the image icon focusing element, A ninth color (943) based on an image icon associated with a first characteristic color offset from the focal path of the image icon focusing element, and an image icon associated with a second characteristic color offset from the focal path of the image icon focusing element, The security device according to claim 10, including the following:

13. The security device according to claim 1, wherein the sealing layer has a refractive index of 1.6 or more.

14. The security device according to claim 1, wherein the refractive image icon focusing element of the array of one or more refractive image icon focusing elements has a diameter of more than 30 microns.

15. The security device according to claim 1, wherein the refractive image icon focusing elements of the array of one or more refractive image icon focusing elements have a diameter of less than 30 microns.

16. The array of refractive image icon light-gathering elements further comprises a spacer layer disposed between the first image icon layer and the second image icon layer, The security device according to claim 1, wherein the spacer layer includes nanoparticles.

17. The security device according to claim 16, wherein the array of one or more refractive image icon focusing elements includes a transition region between the lens surface of the array of one or more refractive image icon focusing elements and the spacer layer.

18. The security device according to claim 1, further comprising two or more refractive image icon focusing element arrays that contact along one or more non-planar boundaries.

19. The security device according to claim 1, wherein the security device has a thickness of 50 microns or less.

20. A security document (101) comprising the security device described in claim 1.

Images