Patent Description:
To prevent counterfeiting by means of scanning, copying, etc., data carriers such as banknotes and financial instruments (for example, value or supporting documents) and other valuable items (for example, luxury brand items) are often equipped with security elements to verify the authenticity of the data carriers and prevent them from being reproduced without authority. However, with the development of reproduction methods, anti-counterfeiting elements that are more practical and more difficult to reproduce are still needed.

Document <CIT> discloses a thin film element.

The objective of the present invention is to provide a thin film element. The thin film element is more practical and more difficult to reproduce.

In order to achieve the above objective, the present invention provides for a thin film element. The thin film element includes at least two low-refractive-index dielectric layers, at least two high-refractive-index dielectric layers, and at least one translucent reflective layer, the at least two high-refractive-index dielectric layers are located between the at least two low-refractive-index dielectric layers, the at least one translucent reflective layer is located between the two high-refractive-index dielectric layers, the thin film element presents at least two colors after reflection on one surface and reflection and transmission on the other surface.

The refractive index of the at least two high-refractive-index dielectric layers is at least <NUM> higher than a refractive index of the at least two low-refractive-index dielectric layers.

The refractive index of the at least two low-refractive-index dielectric layers ranges from <NUM> to <NUM>.

The refractive index of the at least two high-refractive-index dielectric layers ranges from <NUM> to <NUM>.

In some embodiments, a thickness of each of the at least two high-refractive-index dielectric layers ranges from <NUM> to <NUM>.

In some embodiments, one of structures of the thin film element is: the low-refractive-index dielectric layer, the high-refractive-index dielectric layer, the translucent reflective layer, the high-refractive-index dielectric layer, and the low-refractive-index dielectric layer in sequence.

In some embodiments, a thickness of the at least one translucent reflective layer is not greater than <NUM>.

In some embodiments, the at least one translucent reflective layer is a metal layer.

In some embodiments, a material of the metal layer is one of Al, Ag, Cu, Cr, Ni, Fe and Au.

In some embodiments, the at least one translucent reflective layer is provided with a hollowed-out area.

In some embodiments, the at least one translucent reflective layer is made of semi-metal.

In some embodiments, the at least one translucent reflective layer is made of silicon or germanium.

In some embodiments, a color difference between the at least two colors in a CIELab color space is not less than <NUM>.

In some embodiments, the thin film element presents a form of a pattern, text or a code.

In some embodiments, at least one surface of each layer structure of the thin film element is provided with a relief structure.

In some embodiments, the relief structure is one or a combination of a micro-optical relief structure, a diffraction relief structure, and a sub-wavelength relief structure.

Some other embodiments of the present invention further provide a transparent anti-counterfeiting element. The transparent anti-counterfeiting element includes a carrier and the thin film element above mentioned arranged on the carrier.

Still some other embodiments of the present invention further provide a data carrier. The data carrier is provided with the thin film element above mentioned. The thin film element is disposed in a transparent window area, or in a through hole, or above the through hole of the data carrier.

In some embodiments, the data carrier is a value document, a banknote, or an identity card.

With the above technical solutions, the thin film element according to the present invention includes the at least two low-refractive-index dielectric layers, the at least two high-refractive-index dielectric layers, and the at least one translucent reflective layer, the at least two high-refractive-index dielectric layers are located between the at least two low-refractive-index dielectric layers, the at least one translucent reflective layer is located between the two high-refractive-index dielectric layers, and the thin film element presents the at least two colors after reflection on one surface and reflection and transmission on the other surface. The thin film element is able to be used as an anti-counterfeiting element, so as to achieve being more practical and more difficult to reproduce.

Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description.

The accompanying drawings, which are included to provide a further understanding of the present invention and constitute a part of the specification, serve to explain the embodiments of the present invention together with the detailed description below, but are not to be construed as limiting the embodiments of the present invention. In the figures:.

Low-refractive-index dielectric layer; <NUM>. High-refractive-index dielectric layer; <NUM>. Translucent reflective layer; <NUM>. Relief structure; <NUM>. Hollowed-out area; <NUM>. Security thread; <NUM>. Sticker; and <NUM>. Perforated area.

The specific implementations of the embodiments of the present invention are described in detail below with reference to the accompanying drawings. It is to be understood that the specific implementations described herein are merely illustrative and explanatory of the embodiments of the present invention, and are not restrictive of the embodiments of the present invention.

First, the design idea of an embodiment of the present invention is introduced:
Transparent windows have proven to be attractive anti-counterfeiting elements in polymer banknotes and, more recently, in paper banknotes as well because a plurality of security features are allowed. The special role of authenticity protection is played by an anti-counterfeiting element with view-based effects, as these effects are not able to be reproduced even with the most modern photocopiers. The anti-counterfeiting element here is provided with an optically variable element which conveys different image impressions to a viewer from different viewing angles, for example, displaying different color impressions or brightness impressions and/or different graphic patterns depending on the viewing angle. In this context, it is known to adopt anti-counterfeiting elements having multilayer thin film elements, the color impression of which varies with the viewing angle of the viewer. Moreover, when the thin film elements are tilted, the thin film elements change, for example, from green to blue, from blue to magenta or from magenta to green. This change in color, which occurs upon tilting of the thin film elements, is referred to as a color-shift effect hereinafter.

Another special role in authenticity protection is played by a transparent anti-counterfeiting element that shows an appearance contrast between an overhead view and a transmitted light view.

<FIG> is a schematic structural diagram of a thin film element according to an embodiment of the present invention. Referring to <FIG>, the thin film element includes at least two low-refractive-index dielectric layers <NUM> (for example, a layer L1 and a layer L2), at least two high-refractive-index dielectric layers <NUM> (for example, a layer H1 and a layer H2), and at least one translucent reflective layer <NUM> (for example, a layer M).

The at least two high-refractive-index dielectric layers <NUM> are located between the at least two low-refractive-index dielectric layers <NUM>. The at least one translucent reflective layer <NUM> is located between the two high-refractive-index dielectric layers <NUM>. The thin film element presents at least two colors after reflection on one surface and reflection and transmission on the other surface.

In some embodiments, a refractive index of the at least two high-refractive-index dielectric layers <NUM> is at least <NUM> higher than a refractive index of the at least two low-refractive-index dielectric layers <NUM>.

In some embodiments, the refractive index of the at least two low-refractive-index dielectric layers <NUM> ranges from <NUM> to <NUM>. For example, the refractive indexes of the layer L1 and the layer L2 are about <NUM>.

In some embodiments, the refractive index of the at least two high-refractive-index dielectric layers <NUM> ranges from <NUM> to <NUM>. For example, the refractive indexes of the layer H1 and the layer H2 are about <NUM>.

In some embodiments, one of structures of the thin film element is: the low-refractive-index dielectric layer <NUM>, the high-refractive-index dielectric layer <NUM>, the translucent reflective layer <NUM>, the high-refractive-index dielectric layer <NUM>, and the low-refractive-index dielectric layer <NUM> in sequence. For example, the thin film element is of a symmetrical five-layer structure L1/H1/M/H2/L2.

In some embodiments, the at least one translucent reflective layer <NUM> is a metal layer. Specifically, a material of the metal layer is one of Al, Ag, Cu, Cr, Ni, Fe and Au.

The translucent reflective layer <NUM> is made of metal, and depending on a thickness, the translucent reflective layer <NUM> is a homogeneous continuous film layer, or is formed by clusters, that is, by films with discontinuities. An optical effect of Fabry-Perot resonance also occurs in this case.

In some embodiments, a thickness of the at least one translucent reflective layer <NUM> is not greater than <NUM>.

Specifically, referring to <FIG>, the thin film element is of the symmetrical five-layer structure L1/H1/M/H2/L2, wherein L1 and L2 are the low-refractive-index dielectric layers <NUM>, H1 and H2 are the high-refractive-index dielectric layers <NUM>, and the absorptivity of visible light by dielectric materials is very low. The refractive indexes of L1 and L2 are about <NUM>, wherein L1 is a plastic substrate, L2 is a polymer protective layer, and thicknesses of the two are greater than <NUM>, preferably, greater than <NUM>. The refractive indexes of H1 and H2 are greater than <NUM>, and H1 has the same thickness as H2. M is a metal Ag or Al layer with a thickness of <NUM>.

For another example, referring to <FIG>, the thin film element is of an asymmetrical five-layer structure, wherein L1 and L2 are the low-refractive-index dielectric layers <NUM>, H1 and H2 are the high-refractive-index dielectric layers <NUM>, and the absorptivity of visible light by dielectric materials is very low. The refractive indexes of L1 and L2 are about <NUM>, where L1 is a plastic substrate, L2 is a polymer protective layer, and thicknesses of the two are greater than <NUM>, preferably, greater than <NUM>. H1 and H2 have different materials and/or thicknesses, and the refractive indexes of the two are greater than <NUM>. M is a metal Ag or Al layer with a thickness of <NUM>. The above thin film structure is a PET/ZnS/Al/ZnS/ polymer coating system.

In some embodiments, a thickness of each of the at least two high-refractive-index dielectric layers <NUM> ranges from <NUM> to <NUM>.

In an embodiment, the high-refractive-index dielectric layers <NUM> are made of ZnS or TiO<NUM>. The layer thickness of the high-refractive-index dielectric layers <NUM> is generally between <NUM> and <NUM>. As the color impression of the thin film element is essentially determined by the layer thickness of the high-refractive-index dielectric layers <NUM>, as described in detail below, the thickness is selected based on a desired color impression intensity.

Specifically, referring to <FIG>, L1 is a low-refractive-index transparent substrate, H1 is a high-refractive-index dielectric, M is a metal layer, H2 is a high-refractive-index dielectric, and L2 is a low-refractive-index coating. The refractive indexes of the layer L1 and the layer L2 are <NUM>-<NUM>, preferably <NUM>-<NUM>. The refractive indexes of the layer H1 and the layer H2 are selected as <NUM>-<NUM>, and the thicknesses are <NUM>-<NUM>, preferably, <NUM>-<NUM>. The layer M is a metal or semi-metal layer, with the thickness being not greater than <NUM>, and is able to simultaneously partially reflect and partially transmit incident light. The incident light <NUM> is incident from an upper surface of the thin film element and produces reflected light and transmitted light. The observer will see the reflected light on the same side of the incident light, and the observer will see the transmitted light on the opposite side of the incident light. In the thin film element, the reflected light is different from the transmitted light in color.

Accordingly, the thin film element presents bright metal luster and is essentially achromatic when viewed in the reflected light, and is colorful when viewed in the transmitted light. The chroma <MAT> of the thin film element in the transmitted light is greater than <NUM>, preferably, greater than <NUM>, and particularly preferably, greater than <NUM>. The chroma <MAT> is specified in the CIELab color space.

In the structure of the thin film element in Table <NUM>, L1 is PET, H1 is ZnS, M is Ag, H2 is ZnS, and L2 is PET. In the structure of the thin film element in Table <NUM>, L1 is PET, H1 is ZnS, M is Al, H2 is ZnS, and L2 is PET:.

Further, the thin film element is colored in the transmitted light and has a color-shift effect. When the thin film element is tilted, the color impression of the thin film element changes in the transmitted light, for example, changing from magenta in a vertical view to green in a tilted view. Accordingly, the thin film element is colored in the transmitted light, and when the thin film element is tilted, the thin film element does not change color substantially, but has a transparent color with a change in chroma <MAT> The color impression in the transmitted light is, for example, blue, and the chroma of the blue transparent color changes from a high value in the vertical view to a low value in the tilted view. In this case, when the thin film element is tilted, only the saturation of the recognizable blue transparent color changes.

The at least one surface of the layers of the thin film element according to the embodiment of the present invention is provided with the relief structure, such as a diffraction relief structure (for example, a hologram), a micro-optical relief structure (for example, three-dimensional reproduction of a microlens structure and a serrated structure), or a sub-wavelength grating, moth-eye structure. The thin film element according to the embodiment of the present invention is also able to be combined with an optically variable coating, in particular with a coating that has a combination of a color variable area and a color constant area.

Specifically, <FIG> is a schematic structural diagram of the thin film element with the relief structure according to an embodiment of the present invention. Referring to <FIG>, the structure of the thin film element is, from top to bottom: the low-refractive-index dielectric layer <NUM> is a low-refractive-index transparent substrate, the high-refractive-index dielectric layer <NUM> is a high-refractive-index dielectric, the translucent reflective layer <NUM> is a metal layer, the high-refractive-index dielectric layer <NUM> is the high-refractive-index dielectric, and the low-refractive-index dielectric layer <NUM> is a low-refractive-index coating. The refractive index of the low-refractive-index dielectric layers <NUM> is <NUM>-<NUM>, preferably <NUM>-<NUM>. The refractive index of the high-refractive-index dielectric layers <NUM> is selected as <NUM>-<NUM>, and the thickness is <NUM>-<NUM>, preferably, <NUM>-<NUM>. The translucent reflective layer <NUM> is a metal or semi-metal layer, with the thickness being not greater than <NUM>, and is able to simultaneously partially reflect and partially transmit incident light. The at least one surface of the low-refractive-index dielectric layers <NUM>, the high-refractive-index dielectric layers <NUM>, and the translucent reflective layer <NUM> is modulated by a surface relief structure <NUM>. The surface relief structure <NUM> is a diffraction relief structure (for example, a hologram), a micro-optical relief structure (for example, three-dimensional reproduction of a microlens structure and a serrated structure), or a sub-wavelength grating, moth-eye structure. A transverse size of the diffraction relief structure is <NUM>-<NUM>, and a depth is <NUM>-<NUM>. A transverse size of the microlens structure may be <NUM>-<NUM> and a depth may be <NUM>-<NUM>. A transverse size of the serrated structure is <NUM>-<NUM>, and a depth is <NUM>-<NUM>. A transverse size of the sub-wavelength grating, moth-eye structure is <NUM>-<NUM>, and a depth is <NUM>-<NUM>. The effect of the surface relief structure <NUM> on light includes one or more of wavelength-dependent selective absorption, wavelength-independent undifferentiated absorption, wavelength-dependent modulation of a propagation direction, and wavelength-independent undifferentiated modulation of the propagation direction.

In some embodiments, the at least one translucent reflective layer <NUM> is provided with a hollowed-out area.

In some embodiments, the at least one translucent reflective layer <NUM> is made of semi-metal, preferably, silicon or germanium.

The translucent reflective layer <NUM> of the thin film element according to the embodiment of the present invention, for example, a metal reflective layer, is provided with the hollowed-out area. A hollowing method is chemical corrosion on a metal material by acid or alkali. By providing a special structure in the hollowed-out area, the rate of chemical corrosion at this position and the rate of separation of the metal layer are accelerated by increasing a reaction contact area or creating a vulnerable point, etc. A physical peeling method is also adopted, that is, a peeling layer is disposed in the hollowed-out area. The peeling layer is rapidly dissolved under specific conditions, and a coating structure attached thereto also falls off.

Specifically, <FIG> is a schematic structural diagram of the thin film element with the hollowed-out area according to an embodiment of the present invention. Referring to <FIG>, the structure of the thin film element is, from top to bottom: the low-refractive-index dielectric layer <NUM> is a low-refractive-index transparent substrate, the high-refractive-index dielectric layer <NUM> is a high-refractive-index dielectric, the translucent reflective layer <NUM> is a metal layer, the high-refractive-index dielectric layer <NUM> is the high-refractive-index dielectric, and the low-refractive-index dielectric layer <NUM> is a low-refractive-index coating. The refractive index of the low-refractive-index dielectric layers <NUM> is <NUM>-<NUM>, preferably, <NUM>-<NUM>. The refractive index of the high-refractive-index dielectric layers <NUM> is selected as <NUM>-<NUM>, and the thickness is <NUM>-<NUM>, preferably, <NUM>-<NUM>. The translucent reflective layer <NUM> is a metal or semi-metal layer, with the thickness being not greater than <NUM>, and is able to simultaneously partially reflect and partially transmit incident light. The hollowed-out area <NUM> is provided in the translucent reflective layer <NUM>, so that the incident light substantially completely penetrates through the hollowed-out area <NUM>, without producing an obvious color. A hollowing method is chemical corrosion on a metal material by acid or alkali. By providing a special structure in the hollowed-out area, the rate of chemical corrosion at this position and the rate of separation of the metal layer are accelerated by increasing a reaction contact area or creating a vulnerable point, etc. A physical peeling method is also adopted, that is, a peeling layer is disposed in the hollowed-out area <NUM>. The peeling layer is rapidly dissolved under specific conditions, and a coating structure attached thereto also falls off.

In addition, gaps in the form of the pattern, text or the code are provided in the entire surface of the thin film element.

Further, the thin film element according to the embodiment of the present invention is fabricated by thermal evaporation, electron beam evaporation (EBV), or sputtering, and also has radiation-curable lacquer (for example, UV lacquer), polymers, and a plastic substrate.

Some embodiments of the present invention further provide a transparent anti-counterfeiting element. The transparent anti-counterfeiting element includes a carrier and the above-mentioned thin film element arranged on the carrier.

Meanwhile, some embodiments of the present invention further provide a data carrier. The data carrier is provided with the above-mentioned thin film element.

The thin film element is arranged in a transparent window area, or in a through hole, or above the through hole of the data carrier.

The data carrier is particularly a value document, such as a banknote (particularly a paper banknote), a polymer banknote, or an identity card (such as a credit card, a bank card, a cash card, an authorization card, a personal identity card or a personal particulars page of a passport).

Specifically, <FIG> is a schematic structural diagram of a banknote. Referring to <FIG>, the banknote has the thin film element according to the embodiment of the present invention, and the thin film element is embedded within the banknote in the form of a window security thread <NUM>. In addition, the thin film element is also used in the form of a sticker <NUM>, and a perforated area <NUM> is provided in a substrate of the banknote for light transmission observation.

In addition, the embodiment of the present invention is not limited to the security thread or the banknote, but is used in various thin film elements, for example in labels on goods and packaging, or in security documents, identity cards, passports, credit cards, health care cards, etc. In the banknote and a similar document, in addition to the security thread and the sticker, a wide security bar or a transfer element may also be used, for example.

It is also to be noted that the terms "comprise", "include", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements not only include those elements, but also includes other elements not expressly listed or elements inherent to such process, method, article, or apparatus. An element proceeded by the phrase "comprises a" does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that includes the element.

Claim 1:
A thin film element, comprising at least two low-refractive-index dielectric layers (<NUM>), at least two high-refractive-index dielectric layers (<NUM>), and at least one translucent reflective layer (<NUM>),
the at least two high-refractive-index dielectric layers (<NUM>) are located between the at least two low-refractive-index dielectric layers (<NUM>), the at least one translucent reflective layer (<NUM>) is located between the two high-refractive-index dielectric layers (<NUM>), the thin film element presents at least two colors when an incident light is incident from one surface of the thin film element, one color is produced by reflection and observable from the one surface, and the other color is produced by transmission and observable from the other surface of the thin film element;
a refractive index of the at least two high-refractive-index dielectric layers (<NUM>) is at least <NUM> higher than a refractive index of the at least two low-refractive-index dielectric layers (<NUM>);
a refractive index of the at least two low-refractive-index dielectric layers (<NUM>) ranges from <NUM> to <NUM>;
a refractive index of the at least two high-refractive-index dielectric layers (<NUM>) ranges from <NUM> to <NUM>.