WO2021103670A1 - 光学防伪元件及光学防伪产品 - Google Patents

光学防伪元件及光学防伪产品 Download PDF

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Publication number
WO2021103670A1
WO2021103670A1 PCT/CN2020/110023 CN2020110023W WO2021103670A1 WO 2021103670 A1 WO2021103670 A1 WO 2021103670A1 CN 2020110023 W CN2020110023 W CN 2020110023W WO 2021103670 A1 WO2021103670 A1 WO 2021103670A1
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WIPO (PCT)
Prior art keywords
preset
color
area
micro
counterfeiting
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PCT/CN2020/110023
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English (en)
French (fr)
Inventor
崔海波
孙凯
朱军
Original Assignee
中钞特种防伪科技有限公司
中国印钞造币总公司
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Priority to EP20891577.7A priority Critical patent/EP4067105A4/en
Priority to US17/756,510 priority patent/US20230014229A1/en
Publication of WO2021103670A1 publication Critical patent/WO2021103670A1/zh

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/30—Identification or security features, e.g. for preventing forgery
    • B42D25/328—Diffraction gratings; Holograms
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/30—Identification or security features, e.g. for preventing forgery
    • B42D25/324—Reliefs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/30—Identification or security features, e.g. for preventing forgery
    • B42D25/342—Moiré effects
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/30—Identification or security features, e.g. for preventing forgery
    • B42D25/351—Translucent or partly translucent parts, e.g. windows
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/30—Identification or security features, e.g. for preventing forgery
    • B42D25/36—Identification or security features, e.g. for preventing forgery comprising special materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/30—Identification or security features, e.g. for preventing forgery
    • B42D25/36—Identification or security features, e.g. for preventing forgery comprising special materials
    • B42D25/373—Metallic materials
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/02—Viewing or reading apparatus
    • G02B27/06—Viewing or reading apparatus with moving picture effect
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/60—Systems using moiré fringes
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/18—Diffraction gratings
    • G02B5/1814—Diffraction gratings structurally combined with one or more further optical elements, e.g. lenses, mirrors, prisms or other diffraction gratings
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B3/00—Simple or compound lenses
    • G02B3/0006—Arrays
    • G02B3/0037—Arrays characterized by the distribution or form of lenses
    • G02B3/0056—Arrays characterized by the distribution or form of lenses arranged along two different directions in a plane, e.g. honeycomb arrangement of lenses

Definitions

  • the invention relates to the field of optical anti-counterfeiting, in particular to an optical anti-counterfeiting element and an optical anti-counterfeiting product.
  • microlens array anti-counterfeiting technology has the characteristics of being difficult to imitate and forge in the application of banknotes, ID cards, securities and other items, and has high application value. This technology is conducive to the rapid identification of the public. Together with optical anti-counterfeiting technologies such as holography and optical change, it is widely used in today's high-value-added printed products. It effectively resists the copy function of digital technology and makes forgery difficult.
  • the prior art discloses anti-counterfeiting elements with a micro lens array and a micro graphic array on both surfaces of a substrate.
  • the microlens array is used as a sampling tool to sample the corresponding micrographs, and by designing sampling points under different observation angles, a dynamic enlarged image visible to the human eye can be presented.
  • micro-images are usually colored, so that anti-counterfeiting elements with color characteristics can be observed under a point light source or natural light environment.
  • the graphic strokes are filled with finer microstructures, presenting a black optical effect.
  • due to the very fine structure of the micro graphic about 2 ⁇ m
  • the implementation of the existing coloring process is very difficult.
  • the purpose of the present invention is to provide an optical anti-counterfeiting element and an optical anti-counterfeiting product, which can produce anti-counterfeiting features with color and color change showing a moiré amplification effect, thereby improving the anti-counterfeiting ability and recognition.
  • the optical anti-counterfeiting element includes: a substrate, the substrate includes a first surface and a second surface opposed to each other; formed on the second surface of the substrate
  • the micro-image layer on the upper side, the micro-image layer includes: a micro-image area and a background area for presenting preset image-text information, wherein the micro-image area or the background area is at least partially covered with reflective facets, and The reflective facet is covered with a color modulation structure, and a sampling layer formed on the first surface of the substrate, for sampling the micro image layer, and synthesizing the sampled image into a moiré magnification
  • the preset graphic information of the preset color of the effect includes: a substrate, the substrate includes a first surface and a second surface opposed to each other; formed on the second surface of the substrate
  • the micro-image layer on the upper side, the micro-image layer includes: a micro-image area and a background area for presenting preset image-text information, wherein the micro-image area or the background area is at
  • the micro graphic area covered with the reflective facet or the background area covered with the reflective facet corresponds to the location of the sampling element in the sampling layer.
  • the sampling element in the sampling layer is a conventional cylindrical lens or a Fresnel cylindrical lens.
  • the slope direction of the reflective facet is consistent with the infinite direction of the sampling element in the sampling layer.
  • the longitudinal characteristic size of the reflective facet is smaller than the focal depth of the sampling element in the sampling layer.
  • the color modulation structure is a first group
  • the color modulation structure is used to make the first preset graphic information present the first preset color, and accordingly, the sampling layer samples the micro image layer, and synthesizes the sampled images to be presented in the first
  • the first preset graphic information of the first preset color presenting the moiré magnification effect at a preset location, wherein the first preset location and the first set of reflective facets are located Location related.
  • the micro graphic area includes a second area presenting a second preset graphic information and a third area presenting a third preset graphic information, and the second area is covered with a second set of small reflections.
  • the color modulation structure includes: a second set of color modulation structures for making the second preset graphic information present a second preset Set colors; and a third set of color modulation structures, used to make the third preset graphic information present a third preset color, correspondingly, the sampling layer samples the micro image layer, and the sampled
  • the image is synthesized into the second preset graphic information of the second preset color presenting the moiré magnification effect at the second preset position and the third preset at the third preset position
  • the third preset graphic information with color wherein, the second preset position is related to the position where the second group of reflective facets is located, and the third preset position is related to the third group
  • the position of the reflective facet is related.
  • the micro graphic area includes a fourth area presenting fourth preset graphic information and a fifth area presenting fifth graphic information, and the fourth area is covered with a fourth set of reflective facets
  • the color modulation structure includes: a fourth group of color modulation structures for making the fourth preset graphic information present a fourth preset color; and a fifth group of color modulation structures for making the fifth
  • the preset graphic information presents a fifth preset color, and accordingly, the sampling layer samples the micro image layer, and synthesizes the sampled images into a moiré magnification effect presented at the fourth preset position
  • the fourth preset graphic information of the fourth preset color and the fifth preset graphic information of the fifth preset color presenting a moiré magnification effect at a fifth preset position Wherein the fourth preset position is related to the position of the fourth group of reflective facets, and the fifth preset position is related to the position of the fifth group of color modulation structures.
  • the color modulation structure is a sixth group
  • the color modulation structure is used to make the background area present a sixth preset color.
  • the sampling layer samples the micro image layer and synthesizes the sampled images to be presented at the sixth preset position
  • the color modulation structure includes: a metal film or a dielectric film with a predetermined thickness; and a microstructure with steep side walls, or a subwavelength microstructure.
  • the period of the sampling element ranges from 5 to 500 ⁇ m.
  • the focal length range of the sampling element is 10-100 ⁇ m.
  • the second aspect of the present invention provides an anti-counterfeiting product, which includes the optical anti-counterfeiting element according to the above.
  • the anti-counterfeiting product includes banknotes, ID cards, bank cards or money orders.
  • the present invention creatively designs the micro-graphics area as an area with preset graphics and text information, and covers the micro-graphics area or part of the background area with a reflective facet and a color adjustment structure, thereby
  • the anti-counterfeiting feature with color and color change with moiré magnification effect can be produced without performing the coloring process, thereby improving the anti-counterfeiting ability and recognition.
  • Figure 1 is a structural diagram of an optical anti-counterfeiting element provided by an embodiment of the present invention
  • Figure 2 (a) is a schematic diagram of a sampling layer composed of a conventional cylindrical lens array provided by an embodiment of the present invention
  • Figure 2(b) is a schematic diagram of a sampling layer composed of a Fresnel cylindrical lens array provided by an embodiment of the present invention
  • FIG. 3 is a schematic cross-sectional view of a focal plane of a sampling element provided by an embodiment of the present invention.
  • Figure 4 (a) is a top view of the second surface of the substrate covered with reflective facets according to an embodiment of the present invention
  • Figure 4(b) is a top view of the optical security element viewed from the second surface of the substrate provided by an embodiment of the present invention
  • 4(c) is a schematic diagram of the dynamic effect of the optical anti-counterfeiting element provided by the embodiment of the present invention.
  • 4(d) is a schematic diagram of the dynamic effect of the optical anti-counterfeiting element provided by the embodiment of the present invention.
  • FIG. 5 is a schematic diagram of an optical anti-counterfeiting element and its imaging provided by an embodiment of the present invention
  • FIG. 6 is a schematic diagram of an optical anti-counterfeiting element and its imaging provided by an embodiment of the present invention
  • FIG. 7 is a schematic diagram of an optical anti-counterfeiting element and its imaging provided by an embodiment of the present invention.
  • FIG. 8 is a schematic diagram of an optical anti-counterfeiting element and its imaging provided by an embodiment of the present invention.
  • Fig. 9 is a schematic diagram of an optical anti-counterfeiting element and its imaging provided by an embodiment of the present invention.
  • the moiré magnification effect means that sampling elements with periodic arrangement and micro-graphics and texts are superimposed on each other at a certain angle, and the sampling element array spatially samples the micro-graphics and text arrays to form graphics with magnified pixel effects.
  • Fig. 1 is a schematic structural diagram of an optical anti-counterfeiting element provided by an embodiment of the present invention.
  • the optical anti-counterfeiting element may include: a substrate 1 including a first surface 11 and a second surface 12 opposed to each other;
  • the micro-image layer 2 includes: a micro-image area 21 for presenting preset image and text information and a background area 22, wherein the micro-image area 21 (presenting the preset image and text information) or the background
  • the area 22 (without preset graphic information) is at least partially covered with a reflective facet 3, and the reflective facet 3 is covered with a color modulation structure 4, and a sample formed on the first surface 11 of the substrate 1 Layer 5 is used to sample the micro-image layer 2 and synthesize the sampled images into the preset graphic information with a preset color showing a moiré magnification effect.
  • the reflective facet 3 has two characteristic parameters of inclination (or slope) and azimuth angle (as shown in Figure 4(a)), because each reflective facet 3 is randomly distributed (that is, inclined The angle and azimuth are randomly distributed (microscopically speaking), so when the plane wave is incident, it can reflect the scattered light to the observer's eye to the maximum, so that the observer can observe the anti-counterfeiting feature at multiple angles.
  • the lateral feature size of the reflective facet 3 may be 0.5-500 ⁇ m (preferably 20-200 ⁇ m, most preferably 20-50 ⁇ m), and the vertical feature size may be less than 50 ⁇ m (preferably less than 10 ⁇ m, most preferably 1.5). ⁇ m).
  • the cross-section of the reflective facet 3 can be linear and non-linear, that is, the cross-section of the reflective facet 3 can be a smooth slope without curvature change (that is, a flat surface), or it can be a certain degree of curvature (that is, a curved surface). , For example, part of a parabola, arc, or other shape with curvature).
  • the image collected by the sampling layer can only be in grayscale, realizing a simple "black-gray-white" image.
  • the present invention arranges the "color modulation structure" on the reflective facet 3 (the optical anti-counterfeiting element viewed from the second surface side of the substrate The top view of is shown in Figure 4(a)) to achieve the colorization of the image.
  • a holographic interference exposure method can be used to form the color modulation structure 4 on the reflective facet 3.
  • the color control of the preset graphic information can be realized by changing the parameters of the color modulation structure 4 (for example, feature size and depth, etc.), so as to achieve customized colors, so that the presented graphic information can be It is monochromatic, it can be color, and it can even be gradual.
  • the parameters of the color modulation structure 4 for example, feature size and depth, etc.
  • the color modulation structure 4 may include: a metal film 41 or a dielectric film (not shown) with a predetermined thickness; and a microstructure with steep side walls (not shown), or a subwavelength microstructure 42.
  • the sub-wavelength microstructure 42 and the microstructure with steep side walls (not shown) may be a one-dimensional grating or a two-dimensional grating.
  • a metal film 41 can be added to the sub-wavelength microstructure 30, and the color and/or polarization characteristics can be generated by the plasmon resonance absorption of the metal film 41.
  • the preset thickness of the metal film 41 is less than 50 nm, preferably less than 20 nm.
  • the metal film 41 includes at least one of a metal layer, a metal compound layer, a high/low refractive index material stack, and a Fabry-Perot interferometer.
  • the material of the metal film 41 may be one or more of gold, silver, copper, aluminum, iron, tin, zinc, nickel, chromium, and the like.
  • the metal film 41 may be an aluminum layer formed by vapor deposition, and the thickness is 30 nm.
  • the metal film 41 can also be replaced with a dielectric film, and the dielectric film may be a single-layer dielectric layer or a multi-layer dielectric layer.
  • the dielectric material used can be selected from one or more of MgF 2 , SiO 2 , Al 2 O 3 , MgO, PMMA, TiO 2 , ZnS, and ZnO, and the multilayer dielectric film usually adopts a high-low-high film design.
  • SiO 2 is used , and a three-layer structure (for example, Al (aluminum)/SiO 2 /Cr (chromium)) is vapor-deposited, and the light changes color to yellow to green.
  • a three-layer structure for example, Al (aluminum)/SiO 2 /Cr (chromium)
  • the light-changing color is red to green; for the above-mentioned three-layer structure formed directly on the reflective facet, the light-changing color is yellow to green.
  • the characteristic size of the sub-wavelength microstructure 42 is much smaller than the characteristic size of the reflective facet 3. In order to obtain the size of the sub-wavelength microstructure, it needs to be obtained according to the plasmon resonance conditions. Taking a one-dimensional grating as an example, when incident light is incident on the one-dimensional grating at an angle ⁇ , diffracted light of different orders will be generated. When the diffracted light propagates on the surface of the one-dimensional grating, it resonates with the surface plasmon wave excited on the surface of the metal film, that is, the wave vector is equal. Thus, the relationship between the grating period d and the plasmon resonance wavelength can be obtained:
  • m is the diffraction order of incident light on the grating
  • ⁇ 0 is the wavelength in vacuum
  • n 1 is the refractive index of the metal film
  • ( ⁇ 0 is the dielectric constant of incident light in the medium)
  • ⁇ 1 is the dielectric constant of the metal film.
  • the period of the above-mentioned two-dimensional subwavelength microstructure is variable, and the period in the x-direction and/or y-direction (ie, lateral feature size) can range from 50-700 nm, preferably 200-400 nm.
  • the trench depth of the sub-wavelength microstructure is in the range of 10-500 nm, preferably, the trench depth of the sub-wavelength microstructure is in the range of 50-300 nm.
  • the sub-wavelength microstructure 42 can be a one-dimensional grating or a two-dimensional grating, wherein the grid distribution of the two-dimensional grating can be an orthogonal structure, a honeycomb structure, a two-dimensional Bravais lattice structure, a random structure, etc.; a sub-wavelength microstructure
  • the groove can be sinusoidal, rectangular or sawtooth. It should be understood that the subwavelength microstructure 42 is not limited to the structure described above, and the splicing or combination of these subwavelength microstructures can be used in the actual optical anti-counterfeiting element.
  • the sub-wavelength microstructure 42 is preferably a two-dimensional grating.
  • the microstructure with steep side walls may be a one-dimensional grating or a two-dimensional grating, and its characteristic size in the x-direction and/or y-direction ranges from 0.5 to 100 ⁇ m, preferably from 1 to 20 ⁇ m.
  • the depth range of the microstructure 40 with steep side walls in the z direction is 0.05-10 ⁇ m, preferably 0.1-3 ⁇ m.
  • the sub-wavelength microstructure 42 or the microstructure with steep side walls can be periodic in the x-direction and y-direction, or can be periodic in a certain range , It can also be random.
  • Period means that in the entire range of the optical security element, all microstructures have the same arrangement rules and parameters.
  • Period in a certain range means that the microstructures have the same arrangement rules and parameters in a specific small range, but the microstructures do not have the same arrangement rules and parameters in the entire range of the optical anti-counterfeiting element.
  • Random means that the shape parameters and arrangement of the microstructures do not have the same law, and they are randomly distributed.
  • the sampling element may be a cylindrical lens, for example, a conventional cylindrical lens shown in FIG. 2(a) or a Fresnel cylindrical lens shown in FIG. 2(b). Since the plate-making process of the cylindrical lens is simple and the optical effect can be better achieved, in a preferred embodiment, the sampling element may be a conventional cylindrical lens.
  • the sampling elements in the sampling layer need to be sampled at their focal planes. Therefore, the longitudinal feature size of the reflective facet can be designed to be smaller than that in the sampling layer.
  • the depth of focus of the sampling element Specifically, as shown in FIG. 3, if the focal depth of the sampling element (that is, the longitudinal size of the actual spot of the focal point) is h1, and the longitudinal characteristic size of the reflective facet 3 is h2, the sizes of h2 and h1 can be designed, So that h2 is smaller than h1.
  • the depth of focus range of the sampling element may be 0-5 ⁇ m.
  • the thickness of the sampling element can range from 1 to 15 ⁇ m
  • the focal length D can range from 10 to 100 ⁇ m
  • the period range can be from 5 to 500 ⁇ m (preferably 10 ⁇ m to 50 ⁇ m).
  • the micro graphics and text areas covered with the reflective facets or the reflective facets can be covered.
  • the background area corresponds to the location of the sampling element in the sampling layer.
  • Different image effects can be observed from the front and back sides of the above-mentioned optical anti-counterfeiting element.
  • a sampled and synthesized image can be observed, that is, the optical effect viewed from the front is that the microlens array has a positive effect on the micrographics
  • An optical image with Moiré magnification effect formed by array sampling is also observed, that is, the optical effect viewed from the reverse side is the dynamic light-sensitive effect formed by the arrangement of reflective facets, similar to a rolling star (rolling star) effect.
  • the slope direction of the reflective facet is consistent with the infinity direction of the conventional cylindrical lens; the period of the conventional cylindrical lens is 25 ⁇ m, the height is 6 ⁇ m, the focal length is 35 ⁇ m and the focal depth is 3.5 ⁇ m; the lateral direction of the reflective facet
  • the feature size is preferably 10-50 ⁇ m, and the longitudinal feature size is preferably 1.5 ⁇ m; the period of the sub-wavelength microstructure is 300 nm. .
  • the color modulation structure is a first group of color modulation structures, which are used to make the first preset graphic information present a first preset color.
  • the sampling layer samples the micro image layer, and synthesizes the sampled images into the first preset color of the first preset color presenting the moiré magnification effect presented at the first preset position
  • a preset graphic information for example, an array of letters "A", Figure 5 only shows one letter "A” in the array
  • the sub-wavelength microstructure can modulate the light reflected by the reflective facet into light of the same color (for example, red), so that it can be compared with the micro-images and texts.
  • An image A of a single color (for example, red) appears at a position corresponding to the area 21.
  • the micro-graphics area 21 covered with sub-wavelength microstructures is red, and the background area 22 is yellow; when tilted to a certain angle, the micro-graphics area
  • the color of 21 and the background area 22 are the same, but both are green, so that a colorful dynamic moiré graphic can be formed.
  • the light-changing color is red to green; the uncovered area, the light-changing color is yellow to green, showing dynamic flicker characteristics.
  • the reflection spectrum reflected by the sub-wavelength microstructure can be obtained according to the coupled wave theory.
  • the depth (or groove depth), period, groove type and metal film of the subwavelength microstructure can all affect the resonant absorption wavelength of the reflection spectrum through calculation and simulation analysis. Especially the influence of groove depth is particularly obvious.
  • an optical anti-counterfeiting element with sub-wavelength micro-structures with different groove depths covering two different micro-image areas is shown, as shown in FIG. 6.
  • the micro graphic area includes a second area presenting second preset graphic information (for example, an array of letters "A") and a third area presenting third preset graphic information (for example, the array of letters "B").
  • Area and the second area is covered with a second set of reflective facets and the third area is covered with a third set of reflective facets
  • the color modulation structure includes: a second set of color modulation structures, In order to make the second preset graphic information present a second preset color; and a third set of color modulation structures are used to make the third preset graphic information present a third preset color.
  • the sampling layer samples the micro image layer, and synthesizes the sampled images into the second preset color of the second preset color presenting the moiré magnification effect at a second preset position
  • Two preset graphic information for example, an array of letters "A", Figure 6 only shows one letter "A” in the array
  • the third preset color at the third preset position Preset graphic information (for example, an array of letters "B", FIG. 6 only shows one letter "B” in the array), wherein the second preset position and the position where the second set of reflective facets are located Correlation, and the third preset position is correlated with the position where the third group of reflective facets are located.
  • the micro-graphics area A and the micro-graphics area B are filled with several reflective facets, and the background area is a flat area (not filled with reflective facets); the difference in the micro-graphics area A
  • the sub-wavelength microstructures on the reflective facets are the same (the depth is 120 nm), and the sub-wavelength microstructures on the different reflective facets in the micro graphic area B are the same (the depth is 150 nm).
  • the sub-wavelength microstructures in the micro-image area A can modulate the light reflected by the reflective facets into light of the same color (for example, red), thereby A single-color (for example, red) image A is presented at a position corresponding to the micro-image area A; the sub-wavelength microstructure in the micro-image area B can modulate the light reflected by the reflective facet to the same color (for example, , Blue) light, thereby presenting an image B of a single color (for example, blue) at a position corresponding to the micro-text area B.
  • the same color for example, red
  • the sub-wavelength microstructure in the micro-image area B can modulate the light reflected by the reflective facet to the same color (for example, , Blue) light, thereby presenting an image B of a single color (for example, blue) at a position corresponding to the micro-text area B.
  • the micro-image area A is red
  • the micro-image area B is blue
  • the background area is yellow
  • the micro-image area and the background area have Strong color contrast.
  • the color of the micro graphic area and the background area are the same, but both are green, so that a colorful dynamic moiré graphic can be formed.
  • the light-changing color is red to green
  • the uncovered area the light-changing color is yellow to green, showing dynamic flicker characteristics.
  • the multi-color effect of the anti-counterfeiting element is mainly achieved by changing the groove depth of the sub-wavelength microstructure, in order to reduce the process difficulty of preparing the microstructure during the preparation of the anti-counterfeiting element, the larger-sized reflective facet can be removed ( That is, directly forming a sub-wavelength microstructure on the second surface of the substrate, as shown in FIG. 7), can also make the anti-counterfeiting element exhibit a three-color effect similar to that in the second embodiment.
  • an optical anti-counterfeiting element with sub-wavelength microstructures covering different groove depths in two different micro-image areas is shown, and the sub-wavelength micro-structures directly in the micro-image area B It is covered on the second surface of the substrate (the structure of the reflective facet is omitted), as shown in FIG. 7.
  • the micro graphic area includes a fourth area presenting fourth preset graphic information (for example, an array of letters "A") and a fifth area presenting fifth graphic information (for example, an array of letters "B"), and
  • the color modulation structure includes: a fourth group of color modulation structures, used to make the fourth preset graphic information present a fourth preset color ; And the fifth group of color modulation structures, used to make the fifth preset graphic information present the fifth preset color.
  • the sampling layer samples the micro image layer, and synthesizes the sampled images into the fourth preset color of the fourth preset color presenting the moiré magnification effect at a fourth preset position
  • Four preset graphic information for example, an array of letters "A", Figure 7 only shows one letter "A” in the array
  • the fifth preset showing the moiré magnification effect at the fifth preset position
  • the fifth preset graphic information of the color for example, an array of letters "B", FIG. 7 only shows one letter "B” in the array
  • the fourth preset position is the same as the fourth group
  • the position of the reflective facet is related, and the fifth preset position is related to the position of the fifth group of color modulation structures.
  • the micro-graphics area A is filled with several reflective facets
  • the micro-graphics area B is not filled with reflective facets
  • the micro-graphics area B and the background area are flat areas (not filled with reflective facets).
  • the sub-wavelength microstructures on the different reflective facets in the micro-image area A are the same (the depth is 120nm), and the micro-image area B is covered with sub-wavelength micro-structures with the same groove depth (the depth is 150 nm), That is to say, a planar distribution of sub-wavelength microstructures are introduced in the micro-text area B.
  • the sub-wavelength microstructures in the micro-image area A can modulate the light reflected by the reflective facets into light of the same color (for example, red), thereby A single-color (for example, red) image A is presented at a position corresponding to the micro-text area A; the sub-wavelength microstructures in the micro-text area B can modulate the reflected light from the substrate into the same color (for example, Blue) light, thereby presenting an image B of a single color (for example, blue) at a position corresponding to the micro-text area B.
  • the micro-image area A is red
  • the micro-image area B is blue
  • the background area is yellow, that is, except for the micro-image area and the background area
  • the color of the micro-image area and the background area are the same, but both are green, so that a colorful dynamic moiré image can be formed.
  • the light-changing color is red to green
  • the uncovered area the light-changing color is yellow to green, showing dynamic flicker characteristics.
  • the micro graphic area is the sixth area presenting the sixth preset graphic information (for example, the letter "A” array shown in FIG. 8) and the background area is covered with the fifth group of reflective facets
  • the color modulation structure is a sixth group of color modulation structures, which is used to make the background area present a sixth preset color.
  • the sampling layer samples the micro-image layer, and synthesizes the sampled images into the sixth preset color with the moiré magnification effect at the sixth preset position.
  • the sixth preset graphic information in the background area for example, an array of letters "A", FIG. 8 only shows one letter "A” in the array), wherein the sixth preset position and the fifth The position of the group reflection facet is related.
  • the micro-text area A is a flat area (not filled with reflective facets), and several reflective facets are filled in the background area; different reflective facets in the background area
  • the sub-wavelength microstructure is the same (the depth is 120nm). Viewed from the first surface side (ie, the front side) of the substrate, the sub-wavelength microstructure can modulate the light reflected by the reflective facet into light of the same color (for example, red), so that it can be compared with the micro-images and texts. An image A of a single color (for example, red) appears at the corresponding position of the area.
  • the micro-graphic area A covered with sub-wavelength micro-structures is yellow, and the background area is red; when tilted at a certain angle, the micro-graphic area and The color of the background area is the same, but all of them are green, so that a colorful dynamic moiré graphic can be formed.
  • the light-changing color is red to green; the uncovered area, the light-changing color is yellow to green, showing dynamic flicker characteristics.
  • the area of the background area is generally larger than that of the micro-text area.
  • the design scheme of this second embodiment can make more sub-wavelength microstructures filled in the second substrate. Surface, thus forming a better saturated color.
  • the background area can be made transparent by a precise dealumination process first, and then white ink is applied to the micro graphic area and the background area.
  • An optical effect with a white background can be formed, as shown in Figure 9.
  • the dealumination microstructure period can be 5-50 ⁇ m, and the depth can be 1-15 ⁇ m.
  • the present invention can also arrange reflective facets and microstructures in the background area and the micro-image area at the same time (of course, the structure of the micro-structures in the background area and the micro-image area should be different), as shown in 7.
  • the preset graphic information in the present invention is not limited to the letter "A array” and "B" arrays in the above embodiments, and any other graphic arrays and combinations of specific meanings are also applicable.
  • the color of the imaging can also be modulated by changing the sub-wavelength microstructure, which will not be repeated here.
  • the size of the first structure generally has certain requirements.
  • the longitudinal dimension (ie, the height) of the reflective facet cannot be too high, otherwise its thickness is too high, and it cannot be buried in the paper or pasted on the carrier, resulting in unevenness. Therefore, the height of the reflective facet is generally less than 50 ⁇ m, preferably less than 10 ⁇ m, which is conducive to the application of this feature to the window security thread, buried in paper; or as a wide strip product, pasted on paper or plastic substrate, and It can maintain the flatness of the substrate in the above two cases.
  • the present invention creatively designs the micro-image area as an area with preset image and text information, and covers the micro-image area or part of the background area with a reflective facet and a color adjustment structure, thereby
  • the anti-counterfeiting feature with color and color change with moiré magnification effect can be produced without performing the coloring process, thereby improving the anti-counterfeiting ability and recognition.
  • the present invention also provides an anti-counterfeiting product, which may include the above-mentioned optical anti-counterfeiting element.
  • the optical anti-counterfeiting element can be placed in the above anti-counterfeiting product in such a manner as a window opening security thread, a window opening sticker or a label.
  • the anti-counterfeiting products may include high value-added products such as banknotes, ID cards, bank cards, money orders or securities.

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Abstract

公开了一种光学防伪元件及光学防伪产品。光学防伪元件包括：基材（1），该基材包括相互对立的第一表面（11）和第二表面（12）；形成于基材的第二表面上的微图像层（2），该微图像层包括：呈现预设图文信息的微图文区域（21）及背景区域（22），其中，微图文区域或背景区域内至少部分覆盖有反射小面（3），且该反射小面上覆盖有颜色调制结构（4），以及形成于基材的第一表面上的采样层（5），用于对微图像层进行采样，并将所采样的图像合成为呈现莫尔放大效果的预设颜色的预设图文信息。在无需执行着色工艺的前提下即可产生呈现莫尔放大效果的带有颜色和颜色变化的防伪特征，从而提高了防伪能力和辨识度。

Description

光学防伪元件及光学防伪产品
相关申请的交叉引用
本申请要求2019年11月27日提交的中国专利申请201911184133.8的权益，该申请的内容通过引用被合并于本文。
技术领域
本发明涉及光学防伪领域，具体地涉及一种光学防伪元件及光学防伪产品。
背景技术
微透镜阵列防伪技术在钞票、身份证件、有价证券等物品的应用中具有难以模仿和伪造的特性，具有很高的应用价值。该技术有利于公众快速鉴别，与全息、光变等光学防伪技术一起被广泛应用于当今高附加值印刷品中，有效地抵抗了数码技术的复制功能，使得伪造不易。
现有技术公开了在基材两个表面上分别带有微透镜阵列和微图文阵列的防伪元件。具体地，利用微透镜阵列作为采样工具，对相应的微图文进行采样，通过设计不同观察角度下的采样点，可呈现出人眼可见的动态放大图像。为了有利于公众识别，通常会对微图文进行着色，由此能够在点光源或者自然光的环境下观察到具有颜色特征的防伪元素。目前主要有两种着色工艺方法：一种是在微图文区域内刮墨，即将带有颜色的墨水填充在微图文的笔画沟槽内；另一种是利用维结构着色，即在微图文笔画内填充更细小的微结构，呈现黑色光学效果。但由于微图文结构非常精细(约2μm)，现有的着色工艺的实现非常困难。
发明内容
本发明的目的是为了提供一种光学防伪元件及光学防伪产品，其可产生呈现莫尔放大效果的带有颜色和颜色变化的防伪特征，从而提高了防伪能力和辨识度。
为了实现上述目的，本发明一方面提供一种光学防伪元件，该光学防伪元件包括：基材，该基材包括相互对立的第一表面和第二表面；形成于所述基材的 第二表面上的微图像层，该微图像层包括：呈现预设图文信息的微图文区域及背景区域，其中，所述微图文区域或所述背景区域内至少部分覆盖有反射小面，且该反射小面上覆盖有颜色调制结构，以及形成于所述基材的第一表面上的采样层，用于对所述微图像层进行采样，并将所采样的图像合成为呈现莫尔放大效果的预设颜色的所述预设图文信息。
优选地，覆盖有所述反射小面的所述微图文区域或覆盖有所述反射小面的所述背景区域与所述采样层中的采样元件所在位置相对应。
优选地，所述采样层中的采样元件为常规柱透镜或菲涅尔柱透镜。
优选地，所述反射小面的坡度方向与所述采样层中的采样元件的无限大方向一致。
优选地，所述反射小面的纵向特征尺寸小于所述采样层中的采样元件的焦深。
优选地，在所述微图文区域为呈现第一预设图文信息的第一区域且该第一区域内覆盖有第一组反射小面的情况下，所述颜色调制结构为第一组颜色调制结构，用于使所述第一预设图文信息呈现第一预设颜色，相应地，所述采样层对所述微图像层进行采样，并将所采样的图像合成为呈现在第一预设位置处的呈现莫尔放大效果的所述第一预设颜色的所述第一预设图文信息，其中，所述第一预设位置与所述第一组反射小面所在的位置相关。
优选地，在所述微图文区域包括呈现第二预设图文信息的第二区域与呈现第三预设图文信息的第三区域且所述第二区域内覆盖有第二组反射小面及所述第三区域内覆盖有第三组反射小面的情况下，所述颜色调制结构包括：第二组颜色调制结构，用于使所述第二预设图文信息呈现第二预设颜色；及第三组颜色调制结构，用于使所述第三预设图文信息呈现第三预设颜色，相应地，所述采样层对所述微图像层进行采样，并将所采样的图像合成为呈现在第二预设位置处的呈现莫尔放大效果的所述第二预设颜色的所述第二预设图文信息及在第三预设位置处的所述第三预设颜色的所述第三预设图文信息，其中，所述第二预设位置与所述第二组反射小面所在的位置相关，及所述第三预设位置与所述第三组反射小面所在的位置相关。
优选地，在所述微图文区域内包括呈现第四预设图文信息的第四区域与呈 现第五图文信息的第五区域且所述第四区域内覆盖有第四组反射小面的情况下，所述颜色调制结构包括：第四组颜色调制结构，用于使所述第四预设图文信息呈现第四预设颜色；及第五组颜色调制结构，用于使第五预设图文信息呈现第五预设颜色，相应地，所述采样层对所述微图像层进行采样，并将所采样的图像合成为呈现在第四预设位置处的呈现莫尔放大效果的所述第四预设颜色的所述第四预设图文信息及在第五预设位置处的呈现莫尔放大效果的所述第五预设颜色的所述第五预设图文信息，其中，所述第四预设位置与所述第四组反射小面所在的位置相关，及所述第五预设位置与所述第五组颜色调制结构所在的位置相关。
优选地，在所述微图文区域为呈现第六预设图文信息的第六区域且所述背景区域内覆盖有第五组反射小面的情况下，所述颜色调制结构为第六组颜色调制结构，用于使所述背景区域呈现第六预设颜色，相应地，所述采样层对所述微图像层进行采样，并将所采样的图像合成为呈现在第六预设位置处的呈现莫尔放大效果的具有所述第六预设颜色的所述背景区域的所述第六预设图文信息，其中，所述第六预设位置与所述第五组反射小面所在的位置相关。
优选地，所述颜色调制结构包括：预设厚度的金属膜或介质膜；以及边壁陡直的微结构，或者亚波长微结构。
优选地，所述采样元件的周期范围为5-500μm。
优选地，所述采样元件的焦距范围为10-100μm。
本发明第二方面提供一种防伪产品，该防伪产品包含根据所述的光学防伪元件。
优选地，所述防伪产品包括钞票、身份证、银行卡或汇票。
通过上述技术方案，本发明创造性地将微图文区域设计为具有预设图文信息的区域，并在微图文区域或背景区域的部分区域内覆盖上反射小面及调色调整结构，从而可在无需执行着色工艺的前提下即可产生呈现莫尔放大效果的带有颜色和颜色变化的防伪特征，进而提高了防伪能力和辨识度。
本发明的其他特征和优点将在随后的具体实施方式部分予以详细说明。
附图说明
附图是用来提供对本实用新型的进一步理解，并且构成说明书的一部分， 与下面的具体实施方式一起用于解释本实用新型，但并不构成对本实用新型的限制。在附图中：
图1是本发明实施例提供的光学防伪元件的结构图；
图2(a)是本发明实施例提供的由常规柱透镜阵列组成的采样层的示意图；
图2(b)是本发明实施例提供的由菲涅尔柱透镜阵列组成的采样层的示意图；
图3是本发明实施例提供的采样元件的焦平面的剖面示意图；
图4(a)是本发明实施例提供的基材的第二表面上覆盖有反射小面的俯视图；
图4(b)是本发明实施例提供的从基材的第二表面上观察的光学防伪元件的俯视图；
图4(c)是本发明实施例提供的光学防伪元件的动感效果示意图；
图4(d)是本发明实施例提供的光学防伪元件的动感效果示意图；
图5是本发明实施例提供的光学防伪元件及其成像的示意图；
图6是本发明实施例提供的光学防伪元件及其成像的示意图；
图7是本发明实施例提供的光学防伪元件及其成像的示意图；
图8是本发明实施例提供的光学防伪元件及其成像的示意图；以及
图9是本发明实施例提供的光学防伪元件及其成像的示意图。
附图标记说明
1     基材               2     微图像层
3     反射小面           4     颜色调制结构
5     采样层             11    第一表面
12    第二表面           21    微图文区域
22    背景区域           41    金属膜
42    亚波长微结构
具体实施方式
以下结合附图对本发明的具体实施方式进行详细说明。应当理解的是，此 处所描述的具体实施方式仅用于说明和解释本发明，并不用于限制本发明。
在介绍本发明各个实施例之前，先对光学莫尔放大效果进行简单的定义。所述莫尔放大效果是指具有周期排列性质的采样元件和微图文图形按一定角度相互叠加，采样元件阵列通过对微图文阵列空间采样，形成具有放大像素效果的图文。
图1是本发明实施例提供的光学防伪元件的结构示意图。如图1所示，所述光学防伪元件可包括：基材1，该基材1包括相互对立的第一表面11和第二表面12；形成于所述基材1的第二表面12上的微图像层2，该微图像层2包括：呈现预设图文信息的微图文区域21及背景区域22，其中，所述微图文区域21(呈现预设图文信息)或所述背景区域22(无预设图文信息)内至少部分覆盖有反射小面3，且该反射小面3上覆盖有颜色调制结构4，以及形成于所述基材1的第一表面11上的采样层5，用于对所述微图像层2进行采样，并将所采样的图像合成为呈现莫尔放大效果的预设颜色的所述预设图文信息。
需要说明的是，所述反射小面3具有倾斜角(或斜率)和方位角两个特征参数(如图4(a)所示)，由于每个反射小面3是随机分布的(即倾斜角和方位角是随机分布的(微观上来讲))，故在平面波入射时其可以最大限度地将散射光反射到观察者的眼中，从而使得观察者可以多角度下观察到防伪特征。所述反射小面3的横向特征尺寸可为横向特征尺寸可为0.5-500μm(优选为20-200μm，最优选为20-50μm)，纵向特征尺寸可小于50μm(优选小于10μm，最优选为1.5μm)。另外，所述反射小面3的截面可以是线性的和非线性的，即反射小面3的截面可以是无曲率变化的平滑斜面(即平面)，也可以是具有一定弯曲程度的(即曲面，例如，抛物面、圆弧或其他具有曲率的形状的一部分)。
如果微图文区域或背景区域内只存在反射小面3，那么采样层所采集的图像只能是灰度的形式，实现简单的“黑-灰-白”的图像。为了丰富图像的信息量，增加技术难度以提高防伪能力，并便于公众观察，本发明将“颜色调制结构”布置于反射小面3上(从基材的第二表面侧观察到的光学防伪元件的俯视图展示在图4(a)中)，以实现图像的颜色化。具体地，可使用全息干涉曝光方法在所述反射小面3上形成颜色调制结构4。然后，可通过改变颜色调制结构4的参数(例如，特征尺寸和深度等)来实现对预设图文信息的颜色控制，从而实现订制化的 颜色，由此，所呈现的图文信息可以是单色的，也可以是彩色的，甚至可以是渐变色的。
如图3所示，所述颜色调制结构4可包括：预设厚度的金属膜41或介质膜(未示出)；以及边壁陡直的微结构(未示出)，或者亚波长微结构42。所述亚波长微结构42与所述边壁陡直的微结构(未示出)可以是一维光栅，也可以是二维光栅。
下面简单介绍通过该两种不同的颜色调制结构4实现图像颜色化的原理。
对于图3所示的由预设厚度的金属膜41与亚波长微结构42形成的颜色调制结构4，若颜色调制结构4仅采用周期小于可见光波长的衍射光栅(即亚波长微结构42)，则相应的光学防伪元件将不产生明显的颜色特征。对此，可在亚波长微结构30上增加金属膜41，通过金属膜41的等离子共振吸收产生颜色和/或偏振特征。所述金属膜41的预设厚度小于50nm，优选为小于20nm。金属膜41包括金属层、金属化合物层、高/低折射率材料叠层和法布里-珀罗干涉器中至少一者。其中，所述金属膜41的材料可以为金、银、铜、铝、铁、锡、锌、镍、铬等中一者或多者。优选地，金属膜41可为采用蒸镀的方式形成的铝层，且厚度为30nm。当然，还可以将金属膜41替换为介质膜，所述介质膜可为单层介质层或者多层介质层。所采用的介质材料可以选自MgF 2、SiO 2、Al 2O 3、MgO、PMMA、TiO 2、ZnS、ZnO中的一者或多者，并且多层介质膜通常采用高低高膜系设计。优选地，采用SiO 2，蒸镀三层结构(例如，Al(铝)/SiO 2/Cr(铬))，光变颜色为黄变绿。对于形成于二维光栅区域之上的上述三层结构，光变颜色为红色变绿；对于直接形成于反射小面之上的上述三层结构，光变颜色为黄变绿。
所述亚波长微结构42的特征尺寸远小于所述反射小面3的特征尺寸。为得到亚波长微结构的尺寸，需要根据等离子体共振条件得到。以一维光栅为例，当入射光以角度θ入射到一维光栅上时，会产生不同级次的衍射光。当衍射光在一维光栅表面传播时，其与金属膜表面激发的表面等离子体波产生共振，即波矢相等。由此，可得到光栅周期d与等离子体共振波长之间的关系：
Figure PCTCN2020110023-appb-000001
其中，m为入射光在光栅上的衍射级次，λ 0为真空中的波长，n 1为金属膜的折射率，
Figure PCTCN2020110023-appb-000002
(ε 0为入射光在介质中的介电常数)，ε 1为金属膜的介电常数。由公式(1)可得二维亚波长周期d。
为了实现多种颜色，上述二维亚波长微结构的周期是可变的，在x方向和/或y方向上(即横向特征尺寸)的周期范围可为50-700nm，优选200-400nm。并且，亚波长微结构的沟槽深度位于10-500nm的范围内，优选地，亚波长微结构的沟槽深度位于50-300nm的范围内。
亚波长微结构42可以为一维光栅或二维光栅，其中，二维光栅的栅格分布可以是正交结构、蜂窝结构、二维布拉维点阵结构、随机结构等；亚波长微结构的槽型可以是正弦形、矩形或锯齿形等。应当理解的是，亚波长微结构42并不局限于以上描述的结构，而且实际的光学防伪元件中可以采用这些亚波长微结构的拼接或组合。亚波长微结构42优选为二维光栅。
对于由预设厚度的金属膜与边壁陡直的微结构形成的颜色调制结构(未示出)，由于边壁陡直的微结构的上下表面具有垂直的高度差，因此，在入射光的照射下，任两束反射光的光程发生变化，出现光程差，导致该两束反射光之间发生干涉现象，最终在反射方向上获得具有特定颜色的反射光。所述边壁陡直的微结构可以是一维光栅，也可以是二维光栅，其在x方向和/或y方向的特征尺寸范围为0.5-100μm，优选为1-20μm。所述边壁陡直的微结构40在z方向的深度范围为0.05-10μm，优选为0.1-3μm。
亚波长微结构42或边壁陡直的微结构(未示出)(该两者可简称为微结构)在x方向和y方向上可以是周期性的，也可以在一定范围内具有周期性，也可以是随机的。“周期”的含义为在整个光学防伪元件的范围内，所有微结构都是具有相同的排布规律和参数。“一定范围内具有周期性”的含义为在特定小范围内微结构具有相同的排布规律和参数，但是在整个光学防伪元件的范围内微结构不具有相同的排布规律和参数。“随机”含义为在微结构的自身形状参数和排布无相同的规律，是任意分布的。
由于微图文区域内的预设图文信息的笔画宽度很小(例如，一般小于3μm)，而所述反射小面3的横向特征尺寸一般大于20μm，故为了在较小尺寸的笔画内填充较大尺寸的反射小面，可采用柱图文的分布方式，也就是说，将所述反射小 面的坡度方向(即倾斜面方向)与所述采样层中的采样元件的无限大方向一致。由此，由上述采样层采集得到的信息才能更准确地反映图文信息的光学特征。因此，所述采样元件可为柱透镜，例如，可为图2(a)所示的常规柱透镜或图2(b)所示的菲涅尔柱透镜。由于柱透镜的制版加工工艺简单，能够更好的实现光学效果，故在优选实施例中，所述采样元件可为常规柱透镜。
为了形成清晰的呈现莫尔放大效果的彩色图像，需要实现所述采样层中的采样元件在其焦平面处进行采样，故可设计所述反射小面的纵向特征尺寸小于所述采样层中的采样元件的焦深。具体地，如图3所示，若采样元件的焦深(即焦点的实际斑点的纵向尺寸)为h1，所述反射小面3的纵向特征尺寸为h2，则可设计h2、h1的大小，以使得h2小于h1。所述采样元件的焦深范围可为0-5μm。并且，所述采样元件的厚度范围可为1-15um、焦距D范围可为10-100μm以及周期范围可为5-500μm(优选为10μm至50μm)。
另外，为了确保能够更有效地采样层能够采集预设图文的信息，可在本发明实施例中将覆盖有所述反射小面的所述微图文区域或覆盖有所述反射小面的所述背景区域与所述采样层中的采样元件所在位置相对应。
从上述光学防伪元件的正、反两面可观察到不同的图像效果。具体而言，在所述基材1的第一表面11侧(即从正面观察)，可以观察到经采样合成的图像，也就是说，从正面观察的光学效果为微透镜阵列对微图文阵列采样形成的呈现莫尔放大效果的光学图像。同时在第二表面12侧(即从反面观察)，还可观察到动感闪烁特征，也就是说，从反面观察的光学效果为反射小面经排列可形成的动感光变效果，类似于滚动星(rolling star)效果。对于反面观察的情况，在平面波入射时，每个独立的反射小面的倾斜角和方位角是按照一定的规律(从宏观上来讲)设计的(如图4(b)所示)，该设计要求观察者的眼在某一角度观察时，在一定宽度横条区域范围内的反射小面都能够反射到观察者的眼中，则观察者可看到闪烁的亮条线。当防伪元件倾斜时，闪烁的亮条线位置也会随着移动，即产生了动感效果，如图4(c)所示。另外，通过理论设计，也可以形成相对运动的闪烁亮条线，如图4(d)所示。
具体地，下面通过4个应用例对光学防伪元件的具体结构及成像结果进行详细地说明。在各个实施例中，反射小面的坡度方向与常规柱透镜的无限大方向 相一致；常规柱透镜的周期为25μm、高度为6μm、焦距为35μm及焦深为3.5μm；反射小面的横向特征尺寸优选为10-50μm、纵向特征尺寸优选为1.5μm；亚波长微结构的周期为300nm。。
实施例一
在所述微图文区域为呈现第一预设图文信息(例如，图5所示的字母“A”阵列)的第一区域且该第一区域内覆盖有第一组反射小面的情况下，所述颜色调制结构为第一组颜色调制结构，用于使所述第一预设图文信息呈现第一预设颜色。相应地，所述采样层对所述微图像层进行采样，并将所采样的图像合成为呈现在第一预设位置处的呈现莫尔放大效果的所述第一预设颜色的所述第一预设图文信息(例如，字母“A”阵列，图5仅示出阵列中的一个字母“A”)，其中，所述第一预设位置与所述第一组反射小面所在的位置相关。
如图5所示，对于微图文层而言，微图文区域21内填充若干个反射小面，且背景区域22为平坦区域(未填充有反射小面)；不同反射小面上的亚波长微结构相同(深度为120nm)。从所述基材的第一表面侧(即正面)来看，所述亚波长微结构可将反射小面所反射的光线调制为同一颜色(例如，红色)的光线，从而在与微图文区域21相对应的位置处呈现单一颜色(例如，红色)的图像A。也就是说，通过采样层对微图文层采样，可得到以下结果：覆盖有亚波长微结构的微图文区域21为红色，背景区域22为黄色；当倾斜一定角度后，微图文区域21与背景区域22的颜色一致，可都为绿色，从而可形成彩色的动态莫尔图文。从所述基材的第二表面侧(即反面)来看，光变颜色为红色变绿；未覆盖区域，光变颜色为黄变绿，呈现动感闪烁特征。
实施例二
经亚波长微结构反射的反射谱可根据耦合波理论得到，通过计算模拟分析得到亚波长微结构的深度(或沟槽深度)、周期、槽型及金属膜都会影响反射谱的共振吸收波长。尤其是沟槽深度的影响尤为明显。在该实施例二中，示出了在两个不同的微图文区域覆盖不同槽深的亚波长微结构的光学防伪元件，如图6所示。
在所述微图文区域包括呈现第二预设图文信息(例如，字母“A”阵列)的第二区域与呈现第三预设图文信息(例如，字母“B”阵列)的第三区域且所述 第二区域内覆盖有第二组反射小面及所述第三区域内覆盖有第三组反射小面的情况下，所述颜色调制结构包括：第二组颜色调制结构，用于使所述第二预设图文信息呈现第二预设颜色；及第三组颜色调制结构，用于使所述第三预设图文信息呈现第三预设颜色。相应地，所述采样层对所述微图像层进行采样，并将所采样的图像合成为呈现在第二预设位置处的呈现莫尔放大效果的所述第二预设颜色的所述第二预设图文信息(例如，字母“A”阵列，图6仅示出阵列中的一个字母“A”)及在第三预设位置处的所述第三预设颜色的所述第三预设图文信息(例如，字母“B”阵列，图6仅示出阵列中的一个字母“B”)，其中，所述第二预设位置与所述第二组反射小面所在的位置相关，及所述第三预设位置与所述第三组反射小面所在的位置相关。
对于微图文层而言，微图文区域A及微图文区域B内填充若干个反射小面，且背景区域为平坦区域(未填充有反射小面)；微图文区域A内的不同反射小面上的亚波长微结构相同(深度为120nm)，及微图文区域B内的不同反射小面上的亚波长微结构相同(深度为150nm)。从所述基材的第一表面侧(即正面)来看，微图文区域A内的亚波长微结构可将反射小面所反射的光线调制为同一颜色(例如，红色)的光线，从而在与微图文区域A相对应的位置处呈现单一颜色(例如，红色)的图像A；微图文区域B内的亚波长微结构可将反射小面所反射的光线调制为同一颜色(例如，蓝色)的光线，从而在与微图文区域B相对应的位置处呈现单一颜色(例如，蓝色)的图像B。也就是说，通过采样层对微图文层采样，可得到以下结果：微图文区域A为红色，微图文区域B为蓝色，背景区域为黄色，即微图文区域与背景区域具有强烈的颜色对比度。当倾斜一定角度后，微图文区域与背景区域的颜色一致，可都为绿色，从而可形成彩色的动态莫尔图文。从所述基材的第二表面侧(即反面)来看，光变颜色为红色变绿；未覆盖区域，光变颜色为黄变绿，呈现动感闪烁特征。
实施例三
由于防伪元件的多色效果主要是通过改变亚波长微结构的槽深来实现的，故为了减小防伪元件制备过程中的制备微结构的工艺难度，可以将较大尺寸的反射小面去除(即直接在基材的第二表面上形成亚波长微结构，如图7所示)，也能使得防伪元件呈现类似于上述实施例二中的三色效果。因此，在该实施例三中， 示出了在两个不同的微图文区域覆盖不同槽深的亚波长微结构的光学防伪元件，且在微图文区域B内所述亚波长微结构直接在覆盖在所述基材的第二表面上(省去反射小面的结构)，如图7所示。
在所述微图文区域包括呈现第四预设图文信息(例如，字母“A”阵列)的第四区域与呈现第五图文信息(例如，字母“B”阵列)的第五区域且所述第四区域内覆盖有第四组反射小面的情况下，所述颜色调制结构包括：第四组颜色调制结构，用于使所述第四预设图文信息呈现第四预设颜色；及第五组颜色调制结构，用于使第五预设图文信息呈现第五预设颜色。相应地，所述采样层对所述微图像层进行采样，并将所采样的图像合成为呈现在第四预设位置处的呈现莫尔放大效果的所述第四预设颜色的所述第四预设图文信息(例如，字母“A”阵列，图7仅示出阵列中的一个字母“A”)及在第五预设位置处的呈现莫尔放大效果的所述第五预设颜色的所述第五预设图文信息(例如，字母“B”阵列，图7仅示出阵列中的一个字母“B”)，其中，所述第四预设位置与所述第四组反射小面所在的位置相关，及所述第五预设位置与所述第五组颜色调制结构所在的位置相关。
对于微图文层而言，微图文区域A内填充若干个反射小面，微图文区域B内未填充反射小面且微图文区域B、背景区域为平坦区域(未填充有反射小面)；微图文区域A内的不同反射小面上的亚波长微结构相同(深度为120nm)，及微图文区域B内覆盖有槽深相同的亚波长微结构(深度为150nm)，也就是说，在微图文区域B内引入平面分布的亚波长微结构。从所述基材的第一表面侧(即正面)来看，微图文区域A内的亚波长微结构可将反射小面所反射的光线调制为同一颜色(例如，红色)的光线，从而在与微图文区域A相对应的位置处呈现单一颜色(例如，红色)的图像A；微图文区域B内的亚波长微结构可将来自基材的反射光线调制为同一颜色(例如，蓝色)的光线，从而在与微图文区域B相对应的位置处呈现单一颜色(例如，蓝色)的图像B。也就是说，通过采样层对微图文层采样，可得到以下结果：微图文区域A为红色，微图文区域B为蓝色，背景区域为黄色，即除了微图文区域与背景区域具有强烈的颜色对比度外，微图文区域A与微图文区域B之间也有强烈的颜色对比度。当倾斜一定角度后，微图文区域与背景区域的颜色一致，可都为绿色，从而可形成彩色的动态莫尔图 文。从所述基材的第二表面侧(即反面)来看，光变颜色为红色变绿；未覆盖区域，光变颜色为黄变绿，呈现动感闪烁特征。
实施例四
在所述微图文区域为呈现第六预设图文信息(例如，图8所示的字母“A”阵列)的第六区域且所述背景区域内覆盖有第五组反射小面的情况下，所述颜色调制结构为第六组颜色调制结构，用于使所述背景区域呈现第六预设颜色。相应地，所述采样层对所述微图像层进行采样，并将所采样的图像合成为呈现在第六预设位置处的呈现莫尔放大效果的具有所述第六预设颜色的所述背景区域的所述第六预设图文信息(例如，字母“A”阵列，图8仅示出阵列中的一个字母“A”)，其中，所述第六预设位置与所述第五组反射小面所在的位置相关。
如图8所示，对于微图文层而言，微图文区域A为平坦区域(未填充有反射小面)，且背景区域内填充若干个反射小面；背景区域内的不同反射小面上的亚波长微结构相同(深度为120nm)。从所述基材的第一表面侧(即正面)来看，所述亚波长微结构可将反射小面所反射的光线调制为同一颜色(例如，红色)的光线，从而在与微图文区域相对应的位置处呈现单一颜色(例如，红色)的图像A。也就是说，通过采样层对微图文层采样，可得到以下结果：覆盖有亚波长微结构的微图文区域A为黄色，背景区域为红色；当倾斜一定角度后，微图文区域与背景区域的颜色一致，可都为绿色，从而可形成彩色的动态莫尔图文。从所述基材的第二表面侧(即反面)来看，光变颜色为红色变绿；未覆盖区域，光变颜色为黄变绿，呈现动感闪烁特征。
需要说明的是，一般背景区域的面积比微图文区域的面积大，采用该实施例二(例如，图8)的设计方案，可使得更多的亚波长微结构填充在基材的第二表面，从而形成更好饱和度的颜色。
实施例五
为了提高图文区域与背景区域之间的颜色对比度，还可在上述各个实施例的基础上，首先采用精准脱铝工艺将背景区域透明化，然后在微图文区域和背景区域涂布白墨，则能形成白色背景的光学效果，如图9所示。例如，脱铝微结构周期可为5-50μm，且深度可为1-15μm。
当然，本发明还可在背景区域与微图文区域同时布置反射小面及微结构(当 然，背景区域与微图文区域内的微结构的结构应该不相同)，如7所示。并且，本发明中的预设图文信息并不限于上述各个实施例中的字母“A阵列”和“B”阵列，还适用其他任何具有特定意义的图文阵列及其组合这列。
另外，在本实施例中，还可通过改变亚波长微结构来调制成像的颜色，于此不再赘述。
为了能够使上述光学防伪元件适应现有常用的产品承载物，一般为第一结构的尺寸具有一定的要求。例如反射小面的纵向尺寸(即，高度)不能过高，否则其厚度较高，不能将其埋入纸张之中或贴在承载物之上，造成凹凸不平的后果。因此，反射小面的高度一般小于50μm，优选小于10μm，这样有利于该特征应用于开窗安全线，埋于纸张之中；或者作为宽条产品，贴于纸张或塑料基材之上，并能够保持上述两种情况下基材的平整。
综上所述，本发明创造性地将微图文区域设计为具有预设图文信息的区域，并在微图文区域或背景区域的部分区域内覆盖上反射小面及调色调整结构，从而可在无需执行着色工艺的前提下即可产生呈现莫尔放大效果的带有颜色和颜色变化的防伪特征，进而提高了防伪能力和辨识度。
本发明还提供一种防伪产品，该防伪产品可包含上述的光学防伪元件。其中，所述光学防伪元件可以开窗安全线、开窗贴条或贴标等方式置于上述防伪产品中。所述防伪产品可包括钞票、身份证、银行卡、汇票或有价证券等具有高附加值的产品。
以上结合附图详细描述了本发明的优选实施方式，但是，本发明并不限于上述实施方式中的具体细节，在本发明的技术构思范围内，可以对本发明的技术方案进行多种简单变型，这些简单变型均属于本发明的保护范围。
另外需要说明的是，在上述具体实施方式中所描述的各个具体技术特征，在不矛盾的情况下，可以通过任何合适的方式进行组合。为了避免不必要的重复，本发明对各种可能的组合方式不再另行说明。
此外，本发明的各种不同的实施方式之间也可以进行任意组合，只要其不违背本发明的思想，其同样应当视为本发明所公开的内容。

Claims (14)

  1. 一种光学防伪元件，其特征在于，该光学防伪元件包括：
    基材，该基材包括相互对立的第一表面和第二表面；
    形成于所述基材的第二表面上的微图像层，该微图像层包括：呈现预设图文信息的微图文区域及背景区域，其中，所述微图文区域或所述背景区域内至少部分覆盖有反射小面，且该反射小面上覆盖有颜色调制结构，以及
    形成于所述基材的第一表面上的采样层，用于对所述微图像层进行采样，并将所采样的图像合成为呈现莫尔放大效果的预设颜色的所述预设图文信息。
  2. 根据权利要求1所述的光学防伪元件，其特征在于，覆盖有所述反射小面的所述微图文区域或覆盖有所述反射小面的所述背景区域与所述采样层中的采样元件所在位置相对应。
  3. 根据权利要求1所述的光学防伪元件，其特征在于，所述采样层中的采样元件为常规柱透镜或菲涅尔柱透镜。
  4. 根据权利要求1所述的光学防伪元件，其特征在于，所述反射小面的坡度方向与所述采样层中的采样元件的无限大方向一致。
  5. 根据权利要求1所述的光学防伪元件，其特征在于，所述反 射小面的纵向特征尺寸小于所述采样层中的采样元件的焦深。
  6. 根据权利要求1所述的光学防伪元件，其特征在于，在所述微图文区域为呈现第一预设图文信息的第一区域且该第一区域内覆盖有第一组反射小面的情况下，所述颜色调制结构为第一组颜色调制结构，用于使所述第一预设图文信息呈现第一预设颜色，
    相应地，所述采样层对所述微图像层进行采样，并将所采样的图像合成为呈现在第一预设位置处的呈现莫尔放大效果的所述第一预设颜色的所述第一预设图文信息，其中，所述第一预设位置与所述第一组反射小面所在的位置相关。
  7. 根据权利要求1所述的光学防伪元件，其特征在于，在所述微图文区域包括呈现第二预设图文信息的第二区域与呈现第三预设图文信息的第三区域且所述第二区域内覆盖有第二组反射小面及所述第三区域内覆盖有第三组反射小面的情况下，所述颜色调制结构包括：第二组颜色调制结构，用于使所述第二预设图文信息呈现第二预设颜色；及第三组颜色调制结构，用于使所述第三预设图文信息呈现第三预设颜色，
    相应地，所述采样层对所述微图像层进行采样，并将所采样的图像合成为呈现在第二预设位置处的呈现莫尔放大效果的所述第二预设颜色的所述第二预设图文信息及在第三预设位置处的所述第三预设颜色的所述第三预设图文信息，其中，所述第二预设位置与所述第 二组反射小面所在的位置相关，及所述第三预设位置与所述第三组反射小面所在的位置相关。
  8. 根据权利要求1所述的光学防伪元件，其特征在于，在所述微图文区域内包括呈现第四预设图文信息的第四区域与呈现第五图文信息的第五区域且所述第四区域内覆盖有第四组反射小面的情况下，所述颜色调制结构包括：第四组颜色调制结构，用于使所述第四预设图文信息呈现第四预设颜色；及第五组颜色调制结构，用于使第五预设图文信息呈现第五预设颜色，
    相应地，所述采样层对所述微图像层进行采样，并将所采样的图像合成为呈现在第四预设位置处的呈现莫尔放大效果的所述第四预设颜色的所述第四预设图文信息及在第五预设位置处的呈现莫尔放大效果的所述第五预设颜色的所述第五预设图文信息，其中，所述第四预设位置与所述第四组反射小面所在的位置相关，及所述第五预设位置与所述第五组颜色调制结构所在的位置相关。
  9. 根据权利要求1所述的光学防伪元件，其特征在于，在所述微图文区域为呈现第六预设图文信息的第六区域且所述背景区域内覆盖有第五组反射小面的情况下，所述颜色调制结构为第六组颜色调制结构，用于使所述背景区域呈现第六预设颜色，
    相应地，所述采样层对所述微图像层进行采样，并将所采样的图像合成为呈现在第六预设位置处的呈现莫尔放大效果的具有所述第 六预设颜色的所述背景区域的所述第六预设图文信息，其中，所述第六预设位置与所述第五组反射小面所在的位置相关。
  10. 根据权利要求1所述的光学防伪元件，其特征在于，所述颜色调制结构包括：
    预设厚度的金属膜或介质膜；以及
    边壁陡直的微结构，或者亚波长微结构。
  11. 根据权利要求1所述的光学防伪元件，所述采样元件的周期范围为5-500μm。
  12. 根据权利要求1所述的光学防伪元件，所述采样元件的焦距范围为10-100μm。
  13. 一种防伪产品，其特征在于，该防伪产品包含根据权利要求1-12中任一项权利要求所述的光学防伪元件。
  14. 根据权利要求13所述的防伪产品，其特征在于，所述防伪产品包括钞票、身份证、银行卡或汇票。
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