Patent Description:
Due to its unique visual effect and recognizability, an optical anti-counterfeiting element is widely applied to high-security products such as banknotes, credit cards, passports and securities, as well as other high value-added products.

The micro-lens array type anti-counterfeiting technology utilizes a micro-lens as a micro-sampling tool to sample a corresponding micro-graph. A dynamic enlarged image being animated and visible is presented by designing sampling points under different observation angles. Disclosed in the patent documents such as <CIT>, <CIT>, <CIT>, and <CIT> is the same type of anti-counterfeiting element in which two surfaces of a substrate are provided with a micro-lens array and a micro-graph array separately. Such an anti-counterfeiting element can only be observed from one side of the substrate, and the micro-lens array performs a moire enlargement on the micro-graph array, so as to reproduce a pattern with a certain depth of field or dynamic effect. However, features cannot be observed from the other side (micro-graph array side).

Also disclosed in <CIT> is an embodiment in which an anti-counterfeiting element is observed from both sides. Two surfaces of a substrate are provided with a micro-lens array and a micro-graph array separately, and then two or three layers of substrates are compounded. The anti-counterfeiting element of this structure has the following disadvantages: (<NUM>) a plate-making process is complicated, and it is required to manufacture a plurality of original plates for micro-lens arrays and micro-graph arrays on different surfaces separately; (<NUM>) in a production process, it is required to align the micro-lens array with the micro-graph array repeatedly, so the process is more complicated and the controllability is poor; and (<NUM>) a thickness of the anti-counterfeiting element is greatly increased, which is not conducive to the design and application of some high-security products.

<CIT> discloses a method for producing a security element in the form of a lenticular flip, including a micro-optical layer, a carrier substrate and an image layer, the image layer comprising n images for n = <NUM> to i which are visible from an n-th observation angle associated with the n-th image, and n being at least <NUM>. The images are imaged on a photoresist with parallel light in contact print or by means of projection. After the photoresist is developed, an image layer which comprises the i images is present.

<CIT> discloses a security device. The security device includes a transparent substrate having opposing first and second surfaces; a first focusing element array disposed on the first surface of the transparent substrate; a second focusing element array disposed on the secondsurface of the transparent substrate; a first image array disposed on or in the transparent substrate in a first image array plane and configured to co-operate with the first focusing element array to exhibit an optically variable effect when viewed from a first side of the security device; and a second image array disposed on or in the transparent substrate in a second image array plane, different from the first image array plane, the second image array being configured to co-operate with the second focusing element array to exhibit an optically variable effect when viewed from a second side of the security device. At least the first image array is further configured to exhibit a first static macroimage when viewed from the second side of the device.

The present invention aims to provide an optical anti-counterfeiting element and an anti-counterfeiting product, which are configured to solve or at least partially solve the technical problems described as above.

In order to realize the objectives described as above, the embodiment of the present invention provides an optical anti-counterfeiting element. The optical anti-counterfeiting element includes: a substrate, the substrate including a first surface and a second surface opposite each other; a first micro-embossment structure at least partially covering the first surface, the first micro-embossment structure including a first micro-lens array and a first micro-graph array; and a second micro-embossment structure at least partially covering the second surface, the second micro-embossment structure including a second micro-lens array and a second micro-graph array; and wherein the first micro-lens array is configured to sample and synthesize the second micro-graph array, so as to form a first reproduced image, and the second micro-lens array is configured to sample and synthesize the first micro-graph array, so as to form a second reproduced image, wherein: a machining depth of the first micro-embossment structure and the second micro-embossment structure is less than <NUM> microns; and/or a height of the first micro-lens array and the second micro-lens array is not greater than <NUM> microns; and/or a machining depth of the first micro-graph array and the second micro-graph array is <NUM>-<NUM> microns.

Accordingly, the present invention further provides an anti-counterfeiting product using the optical anti-counterfeiting element described as above.

Each of the optical anti-counterfeiting element and the anti-counterfeiting product using the optical anti-counterfeiting element provided by the embodiment of the present invention includes the substrate and micro-embossment structures on two surfaces of the substrate, each of the micro-embossment structures including the micro-lens array and the micro-graph array, and the micro-lens arrays on the two surfaces sampling and enlarging the micro-graph arrays on the other surfaces separately, so as to form the reproduced images. The present invention has the following advantages: (<NUM>) observing the sampled and enlarged reproduced image from both sides of the substrate separately realizes better anti-counterfeiting performance and visual effect than observing from only one side; (<NUM>) the micro-lens array and the micro-graph array on one surface are manufactured on the same original plate, so the quantity and complexity of the original plate to be manufactured are reduced for the anti-counterfeiting element which is configured to be observed from both sides; (<NUM>) during production, it is only required to perform alignment once, so process difficulty is the same as that of an anti-counterfeiting element observed from one side, and a process flow is simple; and (<NUM>) since the total layer number of the micro-lens array or micro-graph array and the layer number of the substrate are not increased, the anti-counterfeiting element has no increase in thickness compared with the element observed from one side, thereby being suitable for being applied to various anti-counterfeiting products.

Other features and advantages of the embodiment of the present invention will be described in detail in the specific implementation that follows.

The accompanying drawings, which are used for providing further understanding of the embodiment of the present invention and constitute a part of the description, together with the following specific implementation, serve to explain the embodiment of the present invention instead of limiting same. In the accompanying drawings:.

The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings.

<FIG> schematically shows an optical anti-counterfeiting element <NUM> of one implementation of the present invention. The optical anti-counterfeiting element <NUM> according to the implementation of the present invention includes: a substrate <NUM>, the substrate <NUM> including a first surface and a second surface opposite each other; a first micro-embossment structure located on the first surface of the substrate <NUM>, the first micro-embossment structure at least partially covering the first surface of the substrate <NUM> and including a first micro-lens array <NUM> and a first micro-graph array <NUM>, the first micro-graph array <NUM> fully or partially overlapping a surface of the first micro-lens array <NUM>; and a second micro-embossment structure located on the second surface of the substrate <NUM>, the second micro-embossment structure at least partially covering the second surface of the substrate <NUM> and including a second micro-lens array <NUM> and a second micro-graph array <NUM>, the second micro-graph array <NUM> fully or partially overlapping a surface of the second micro-lens array <NUM>. The first micro-lens array <NUM> is configured to sample and synthesize the second micro-graph array <NUM>, so as to form a reproduced image. The second micro-lens array <NUM> is configured to sample and synthesize the first micro-graph array <NUM>, so as to form a reproduced image.

The first micro-lens array <NUM> and/or the second micro-lens array <NUM> shown in <FIG> is a spherical micro-lens array. However, it should be understood by those skilled in the art that the first micro-lens array <NUM> and the second micro-lens array <NUM> may be one or more of an aperiodic array, a random array, a periodic array, and a locally periodic array composed of a plurality of micro-lens units. The micro-lens unit may be a refractive micro-lens, a diffractive micro-lens or any combination thereof, wherein the refractive micro-lens may be a spherical micro-lens, an ellipsoidal micro-lens, a cylindrical micro-lens or any other geometric optics-based micro-lenses with any geometric shape, the diffractive micro-lens may be a harmonic diffractive micro-lens, a planar diffractive micro-lens or a Fresnel zone plate, and certainly, in addition to the Fresnel zone plate, it is also possible to select a continuous curved surface type or a stepped surface type structure as the micro-lens unit. In addition, the first micro-lens array <NUM> and the second micro-lens array <NUM> may be composed of one or more forms of the micro-lens units described as above.

A surface micro-structure used by a micro-graph array in the first micro-graph array <NUM> and/or the second micro-graph array <NUM> may be composed of at least one of a diffractive micro-embossment structure, a non-diffractive micro-embossment structure and a scattering structure. A specific shape may be any surface micro-structure having, but not limited to, the following features: one or more continuous curved structures, one or more rectangular structures, one or more sawtooth-shaped prisms, or a splice or combination thereof.

The first micro-graph array <NUM> and/or the second micro-graph array <NUM> may be one or more of an aperiodic array, a random array, a periodic array, or a locally periodic array composed of a plurality of micro-graph units. The micro-graph unit may be composed of one or more of a convex micro-graph unit, a concave micro-graph unit, a relief embossment unit or a periodic relief grating micro-graph unit, wherein the first micro-graph array <NUM> and the second micro-graph array <NUM> may use the same or different types of micro-graph units.

<FIG> shows a schematic diagram of the convex micro-graph unit. As shown in <FIG>, the convex micro-graph unit may cover a surface of the micro-lens unit, or a gap between the micro-lens units on the surface of the substrate. <FIG> show the schematic diagrams of the concave micro-graph unit, the relief embossment unit and the periodic relief grating micro-graph unit separately, as shown in <FIG>, the concave micro-graph unit, the relief embossment unit and the periodic relief grating micro-graph unit may preferably cover only the gap between the micro-lens units on the surface of the substrate.

The first micro-graph array <NUM> and the second micro-graph array <NUM> may be formed of a micro-structure covering the surface of the micro-lens array (including the micro-lens unit and the gap between the micro-lens units). The micro-graph array shown in <FIG> is composed of the convex micro-graph unit formed on the surface of the micro-lens unit and in the gap between the micro-lens units.

The first micro-graph array <NUM> and the second micro-graph array <NUM> may also cover only the gap between the micro-lens units instead of the surface of the micro-lens unit, which is shown in <FIG>, in which the first micro-graph array <NUM> and the second micro-graph array <NUM> are composed of the concave micro-graph units. In this case, an entire surface of the micro-lens may be configured for optical imaging, so as to improve definition of the sampled and synthesized reproduced image.

Preferably, the first micro-lens array <NUM> and the second micro-lens array <NUM> may use different types of micro-lens units, and the first micro-graph array <NUM> and the second micro-graph array <NUM> may use different types of micro-graph units or micro-graph embossment structures. <FIG> shows one possible case, in which the first micro-lens array <NUM> and the first micro-graph array <NUM> on the first surface of the substrate <NUM> are a continuous spherical micro-lens array and a micro-graph array composed of the convex micro-graph unit respectively; and the second micro-lens array <NUM> and the second micro-graph array <NUM> on the second surface of the substrate <NUM> are a micro-lens array composed of a Fresnel lens and a micro-graph array composed of the concave micro-graph unit respectively.

Preferably, the first micro-lens array <NUM> and the second micro-lens array <NUM> may selectdifferent arrangement modes separately, to exhibit different reproduction effects as observed from both sides of the substrate while reducing or eliminating interference between the micro-lens array and the micro-graph array on the same surface of the substrate. Accordingly, corresponding to the first micro-lens array <NUM> and the second micro-lens array <NUM>, the second micro-graph array <NUM> and the first micro-graph array <NUM> select different arrangement modes.

<FIG> schematically shows an arrangement mode of a continuous spherical first micro-lens array <NUM> and a second micro-graph array <NUM> overlapping and corresponding to same on the other surface, in which arrangement periods of the quadrilateral periodically arranged first micro-lens array <NUM> and the quadrilateral periodically arranged second micro-graph array <NUM> have a slight difference, so as to be within a range of reproduction based on sampling and synthesizing, and in particular, further satisfy a condition of a moire enlargement. <FIG> schematically shows another arrangement mode of a continuous spherical second micro-lens array <NUM> and a first micro-graph array <NUM> overlapping and corresponding to same on the other surface, in which arrangement directions of the hexagonal periodically arranged second micro-lens array <NUM> and the hexagonal periodically arranged first micro-graph array <NUM> are relatively and slightly staggered, so as to be within the range of reproduction based on sampling and synthesizing, and in particular, further satisfy the condition of the moire enlargement.

Preferably, a period of the periodic or partially periodic micro-lens array <NUM>, second micro-lens array <NUM>, first micro-graph array <NUM>, and second micro-graph array <NUM> according to the implementation of the present invention may be <NUM>-<NUM> microns, preferably <NUM>-<NUM> microns, and a focal length of the first micro-lens array <NUM> and the second micro-lens array <NUM> may be <NUM>-<NUM> microns, preferably <NUM>-<NUM> microns.

According to the invention, a machining depth of the micro-embossment structure is less than <NUM> microns; and/or a height of the micro-lens is not greater than <NUM> microns, and a machining depth of a micro-graph is Z <NUM>-<NUM> microns.

An original plate of the micro-embossment structure including the first micro-lens array <NUM> and the first micro-graph array <NUM>, or an original plate of the micro-embossment structure including the second micro-lens array <NUM> and the second micro-graph array <NUM> may be implemented through a micro-machining process. Particularly, the original plate may be implemented through processes such as ultraviolet lithography exposure, laser direct writing exposure, electron beam direct writing exposure, and reactive ion etching, and may also be implemented in combination with processes such as hot melt reflow. But it should be understood that their implementation methods are not limited to the methods described as above. Preferably, surface micro-structures of the micro-lens array and the micro-graph array included in the optical anti-counterfeiting element <NUM> of the implementation of the present invention are made at one time through one process or mutual cooperation among a plurality of micro-machining processes described as above. The micro-lens array and the micro-graph array are simultaneously copied in a production procedure of subsequent batch copying (for example, using an imprint process of an ultraviolet curing material), without involving separate step-by-step copying of the micro-lens array and the micro-graph array.

Preferably, the substrate <NUM> in the optical anti-counterfeiting element <NUM> according to the present invention may be a colorless or colored medium layer which is at least partially transparent, or the substrate <NUM> may be a layer of single lens medium film, such as a PET film and a BOPP film. Certainly, it can also be a transparent medium film with a functional coating layer (such as an imprint layer) on the surface, or a multilayer film formed through compounding.

Preferably, the micro-embossment structure of the optical anti-counterfeiting element <NUM> of the present invention may be coated with a protective layer and/or a bonding layer. For example, <FIG> shows an example in which the surface with the first micro-lens array <NUM> and the first micro-graph array <NUM> and the surface with the second micro-lens array <NUM> and the second micro-graph array <NUM> of the optical anti-counterfeiting element <NUM> are coated with the protective layer <NUM>. The protective layer or the bonding layer is formed to protect the optical anti-counterfeiting element <NUM> according to the implementation of the present invention against an external environment or bond the optical anti-counterfeiting element <NUM> according to the implementation of the present invention to an anti-counterfeiting product in consideration of application. Therefore, when the protective layer and the bonding layer are formed, the bonding layer is arranged outside the protective layer (that is, the protective layer is closer to the micro-embossment structure), so as to bond the optical anti-counterfeiting element of the present invention to carriers such as a banknote and paper. The protective layer and/or the bonding layer is bonded to the anti-counterfeiting product. The protective layer and/or the bonding layer may cover part or all of the surface that it coats. When the protective layer and/or the bonding layer is in direct contact with the micro-embossment structure according to the implementation of the present invention, a refractive index of the protective layer or the bonding layer is smaller than that of the micro-embossment structure in contact, and a difference between the refractive index of the protective layer or the bonding layer and the refractive index of the micro-embossment structure is greater than or equal to <NUM>. It should be noted that, during practical application, the difference between the refractive index of the protective layer or the bonding layer and the refractive index of the micro-embossment structure is generally smaller than a difference between a refractive index of a material forming the micro-embossment structure and a refractive index of air, which places higher demands on the micro-lens as a focusing element, for example, a diameter of a bottom surface of the micro-lens needs to be smaller, and a height of the micro-lens needs to be larger.

Preferably, the protective layer or the bonding layer is at least translucent.

Preferably, the protective layer or the bonding layer has a function of increasing a color effect, so as to improve expressive force of the sampled and synthesized reproduced image. For example, an ink, a pigment, a dye, a liquid crystal, a fluorescent material, etc. may be used to make the function of the color effect, and may be implemented, for example, through coating, printing, inkjet, dyeing, deposition, etc..

The optical anti-counterfeiting element <NUM> according to the implementation of the present invention is particularly suitable for manufacturing an anti-counterfeiting transparent window product which may be observed from both sides. The anti-counterfeiting transparent window product is configured for anti-counterfeiting of various high-security products such as a banknote, a credit card, a passport and a security and high value-added products, as well as various packing paper, packing boxes, etc..

The optical anti-counterfeiting element <NUM> according to the present invention may also be used as a label, a logo, a wide strip, a transparent window, a coating film, etc., and may be bonded to various articles through various bonding mechanisms, for example, transferred to the high-security product such as a banknote and a credit card and the high value-added product.

Claim 1:
An optical anti-counterfeiting element, comprising:
a substrate (<NUM>), comprising a first surface and a second surface opposite each other;
a first micro-embossment structure at least partially covering the first surface, the first micro-embossment structure comprising a first micro-lens array (<NUM>) and a first micro-graph array (<NUM>); and
a second micro-embossment structure at least partially covering the second surface, the second micro-embossment structure comprising a second micro-lens array (<NUM>) and a second micro-graph array (<NUM>); and
the first micro-lens array (<NUM>) is configured to sample and synthesize the second micro-graph array (<NUM>), so as to form a first reproduced image, and the second micro-lens array (<NUM>) is configured to sample and synthesize the first micro-graph array (<NUM>), so as to form a second reproduced image;
characterized in that
a machining depth of the first micro-embossment structure and the second micro-embossment structure is less than <NUM> microns; and/or
a height of the first micro-lens array (<NUM>) and the second micro-lens array (<NUM>) is not greater than <NUM> microns; and/or
a machining depth of the first micro-graph array (<NUM>) and the second micro-graph array (<NUM>) is <NUM>-<NUM> microns.