Source: https://patents.google.com/patent/RU2364517C2/en
Timestamp: 2019-12-11 14:57:35
Document Index: 587613533

Matched Legal Cases: ['art 41', 'art 44', 'art 44', 'art 46', 'art 51', 'art 53', 'art 54', 'art 56', 'art 72', 'art 74']

RU2364517C2 - Protection component and method of its manufacturing - Google Patents
Protection component and method of its manufacturing Download PDF
RU2364517C2
RU2364517C2 RU2006141521/12A RU2006141521A RU2364517C2 RU 2364517 C2 RU2364517 C2 RU 2364517C2 RU 2006141521/12 A RU2006141521/12 A RU 2006141521/12A RU 2006141521 A RU2006141521 A RU 2006141521A RU 2364517 C2 RU2364517 C2 RU 2364517C2
RU2006141521/12A
RU2006141521A (en
2005-04-29 Application filed by Гизеке Унд Девриент Гмбх filed Critical Гизеке Унд Девриент Гмбх
2008-06-10 Publication of RU2006141521A publication Critical patent/RU2006141521A/en
2009-08-20 Publication of RU2364517C2 publication Critical patent/RU2364517C2/en
230000003098 cholesteric Effects 0 abstract 1
SUBSTANCE: invention relates to protection component, provided for protection against falsification of important documents, to method of its manufacturing, and also to protection system and to important document. Protection element contains the first light-polarising layer, which is at least at some sections and contains cholesteric liquid-crystalline material, which selectively reflects light with predefined circular polarisation and which is selectively reflects light of the first wave range in the first direction of reflection and light of the second wave range, in the second, different from the first direction of reflection. Protection element contains the second light-polarising layer, which is at least on several sections and selectively reflects light with circular polarisation, opposite to predefined circular polarisation, and selectively reflects light of the first and the second wave range, correspondingly, in the first and the second direction of reflection. Protection element also contains semitransparent filtering layer on which one above the other are the first and the second light-polarising layers. Percolation bed at least partially absorbed light of visible spectrum range and admit light of the first and/or the second wave range.
EFFECT: proposed protection element allows high degree of protection against falsification.
42 cl, 17 dwg
This invention relates to a security element designed to protect against counterfeiting of valuable documents and having one or more liquid crystal layers. In addition, this invention relates to a method for manufacturing such a security element, to a security system that contains, in addition to this security element, a separate display element, and to a valuable document provided with such a security element or such a security system.
To protect against forgery, valuable documents are often equipped with security elements that allow you to establish the authenticity of the document and at the same time serve as protection against unauthorized reproduction. This document can be, for example, a printed security paper, an identification card containing plastic, or another document that needs to be protected from counterfeiting.
As protection elements, elements with variable optical properties are often used, when observing them at different angles, the observer has a different visual image, for example, a different color image. Such a security element is known from patent document EP 0 435 029 A2, provided with a plastic layer containing a liquid crystal polymer, this layer realizing a pronounced color change effect at room temperature. You can combine the variable optical effects of various liquid crystal polymers by coloring some layers with traditional paints, which allows you to create patterns that are visible only when the security elements are tilted. The paints themselves can be introduced into any of the layers or applied as a printed image.
A security element is known from patent document EP 1156934 B1 in which a liquid crystal layer is used as a material with variable optical properties. As an example of implementation, a system of combined printing layers containing a right-handed and left-handed liquid crystal material is described, moreover, these layers look the same under normal lighting, so that the information element formed by the shape or outline of the sections is not visible. This information element can be noticeable only when observing the layers through the corresponding polarizing filter, which will then be highlighted due to the different brightness of the printed layers. However, to obtain this effect, it is necessary to ensure accurate registering when applying liquid crystal layers.
In the described security elements, due to their physical properties, the color change effect of the liquid crystal layers always leads to a change in the wavelength of reflected light, which shifts from the longer wavelength to the shorter wavelength portion of the spectrum when the protection element is observed in a direction that is an angle with the vertical. Thus, the variety of color change options is limited. In addition, the liquid crystal layers realize the functions of the security element only when observed in reflected light, since the effect of a color change cannot be observed in transmitted light, since such layers require the presence of a dark or black background.
Taking into account all of the above, the purpose of this invention is to create a security element of the type described above, which has a high degree of protection against counterfeiting and which does not have the disadvantages inherent in its analogues known from the prior art.
This goal is achieved by means of a security element having the features disclosed in an independent claim. The method of its manufacture, the security system and a valuable document provided with such a security element are disclosed in the claims combined by a single inventive concept. The development options of this invention are the subject of the dependent clauses.
To protect valuable documents from counterfeiting, the present invention provides a security element that comprises a first light-polarizing layer present in at least some areas and containing a cholesteric liquid crystal material that selectively reflects light having a predetermined circular polarization and which also selectively reflects light the first wave range at one angle of reflection and the light of the second wave range at a second, different angle of reflection. The security element further comprises a second light-polarizing layer, which is located at least in some areas and which selectively reflects light having a circular polarization direction opposite to the direction of a predetermined circular polarization, and which also selectively reflects light of the first and second wavelength range below the first and at the second reflection angles, respectively, and a translucent filter layer on which the first and second light-polarizing layers are located one above the other. Here, the filter layer absorbs the light of the visible region of the spectrum at least partially and transmits light of the first and / or second wavelength range.
Such a structure makes it possible to achieve new liquid crystal effects, allowing to increase the degree of protection against crafts. As explained in detail below, due to the interaction of the translucent filter layer with two or three matched liquid crystal layers, translucent security elements can be produced that realize the inverse color-change effect, in which the color image of the security element, unlike traditional color-changing elements, changes color from a shorter wavelength to the side of the longer wavelength when observing the protection element in the direction making an angle with the vertical.
In a first preferred embodiment of the present invention, the second light-polarizing layer is formed of a cholesteric liquid crystal material and selectively reflects light with a circular polarization direction opposite to a predetermined circular polarization direction.
Alternatively, the second light-polarizing layer can be formed from two sublayers, the first sublayer being formed from a cholesteric liquid crystal material and selectively reflecting light with a predetermined circular polarization, and the second sublayer located between the first sublayer and the first light-polarizing layer forms a λ / 2 layer. Here, the λ / 2 layer is preferably formed from a nematic liquid crystal material, the use of which simplifies the manufacture of optically active layers due to the anisotropy of the optical properties of liquid crystals consisting of uniformly oriented rod-shaped molecules.
To weaken the effect of the λ / 2 layer in some areas and / or to create new effects, the λ / 2 layer can also be formed from several sublayers located one above the other and in some areas rotated relative to each other in the plane of the layer. Here, such sublayers are preferably formed from two λ / 4 layers. Due to the various rotations of the two λ / 4 sublayers in some areas in the layer plane, it is possible to systematically control their effect on light with circular polarization, which makes it possible to create, for example, coded grayscale images.
In a preferred embodiment, the first and second light polarizing layers can selectively reflect light of the third wavelength range in the third reflection direction. Here, the translucent filter layer at least partially absorbs visible light and transmits light of the first and / or second and / or third wavelength range.
In a preferred embodiment, the first and second light polarizing layers reflect the light of the visible part of the spectrum in all directions of reflection. In other similar preferred embodiments, the two light-polarizing layers reflect in at least one of the directions of reflection the light of an invisible part of the spectrum, in particular infrared or ultraviolet radiation. The reflection of the radiation of an invisible part of the spectrum can be used, for example, to provide machine-readable signs of authenticity or color-changing effects in which a visible color image appears or disappears when tilted.
The first and second, and also, if necessary, the third direction of reflection can be selected arbitrarily. In order to be able to visually distinguish images of different colors corresponding to two different wave ranges, the first and second, and also, if necessary, the third direction of reflection should preferably differ from each other by a polar angle of at least 20 ° relative to the perpendicular to the surface of the light-polarizing layers. In particular, it is preferable to divide the first and second direction of reflection at a polar angle of at least 40 ° relative to the perpendicular to the surface of the light-polarizing layers. For example, the first reflection direction may be parallel to the surface normal (polar angle θ = 0 °), and the second reflection direction may be 45 ° with the first reflection direction (polar angle θ = 45 °).
In all embodiments, the various layers of the security element may be in the form of symbols and / or patterns. In addition, additional layers consisting of a nematic and / or cholesteric liquid crystal material may be applied. At least one of the light-polarizing layers containing the cholesteric liquid crystal material, and / or, if necessary, at least one layer containing the nematic liquid crystal material, it is advisable to apply in the form of pigments embedded in a binder matrix. Such pigments are easier to apply by printing than liquid crystals in the form of a solution, and at the same time, such high demands on the smoothness of the substrate are not imposed. In addition, for pigment-based inks, it is not necessary to separately ensure uniform orientation.
In a preferred embodiment, both the first and second light polarizing layers may be formed from a cholesteric liquid crystal material and may be in the form of pigments. Here, a mixture consisting of equal parts of the pigments of the first and second light-polarizing layers, it is advisable to enter into the binder matrix. Thus, the first and second light-polarizing layers, which together form a band-stop filter, can be applied in a single layer in a single printing process.
Preferably, the translucent filter layer transmits light of the first, second and, optionally, third wavelength range and absorbs visible light outside these two wavelength ranges. The light that has passed through the protection element is then primarily affected by liquid crystal layers, which makes it possible to create intense and high-contrast color effects in transmitted light.
It may also be provided that the translucent filter layer transmits only the first and / or only the second and / or only the third wavelength range and absorbs visible light outside the first and / or second and / or third wavelength range. Thus, protection elements can be created in which, when tilted, one or more visible color images disappear and the observed areas become dark.
In preferred embodiments of the invention, the translucent filter layer is formed by a dye film or varnish layer. In the latter case, the varnish layer can be applied to a transparent and colorless substrate. Like translucent layers, a translucent filter layer may be in the form of symbols and / or patterns instead of any of the layers or in addition to them.
The translucent layers and the translucent filter layer may be on a substrate which is preferably formed from paper or plastic. Orientation and / or adhesive layers designed to provide orientation of the liquid crystal layers may be between adjacent light-polarizing layers and / or between the light-polarizing layer and the translucent filter layer.
In preferred embodiments, the security element forms a label or transfer element.
The present invention also discloses a method of manufacturing a security element of the type described, in which a first light-polarizing layer containing a cholesteric liquid crystal material, and a second light-polarizing layer that contains at least one (sub) layer containing a cholesteric liquid crystal material, are arranged one above the other on a translucent filter layer. Here, in a preferred embodiment, one or more liquid crystal layers are applied, in particular printed on a substrate. If different liquid crystal layers are applied to different substrates, then after application to the substrate, each such layer can be checked for suitability for further processing and, if necessary, removed. Alternatively, two or more liquid crystal layers can be applied one after the other onto the same substrate.
The liquid crystal material may be applied in the form of a solution or melt. In addition, they can use a cholesteric liquid crystal material, in particular in a paste form, in the form of a UV-hardening cholesteric mixture, and such a system will not contain typical solvents and melt or pigment-based compositions, but rather will contain other types of UV-hardening varnish . Depending on the method used to remove the solvent, the liquid crystal material is subsequently physically dried, oriented and cured. Orientation can be provided directly by the substrate or by so-called orientation layers, as well as by applying shear deformation, electrostatic methods, etc. As for the curing of the liquid crystal material, it can be cured with the formation of a network structure, for example, by ultraviolet radiation or an electron beam (EMC electron beam drying). However, the liquid crystal material may also solidify due to certain added additives.
In a preferred embodiment of the method, the liquid crystal layers located on the substrate are layered on a translucent filter layer or on another liquid crystal layer. After application, the substrate can be removed, in particular using separation layers or laminating glue, the adhesion of which to the substrate is less than its adhesion to the liquid crystal layer. These requirements for the laminating adhesive are especially relevant when the transferred liquid crystal layer is not continuous.
As an alternative, in order to facilitate separation, a continuous auxiliary layer may be applied to the liquid crystal layer on the substrate, the adhesion of which to the substrate is less than its adhesion to the liquid crystal layer. In this case, the laminating adhesive can be applied over the entire surface, and at the same time uncontrolled adhesion will be prevented. Here, the auxiliary layer is mainly a layer of UV varnish.
Preferably, layers of a cholesteric liquid crystal material are formed by combining a nematic liquid crystal system with a torsional vibrational piezoelectric crystal. Here, two cholesteric liquid crystal layers can form upon combining a system of nematic liquid crystals with coordinated first and second piezoelectric crystals with torsional vibration, so that the liquid crystals of the first and second layers will be arranged with the formation of mirror-like spiral structures.
The sublayer λ / 2 of the second light-polarizing layer formed of two sublayers is preferably formed from a nematic liquid crystal material.
The present invention further comprises a security system for securities, valuable documents and products of a similar type, comprising a security element of the type described or a security element made in accordance with the described method, and a separate display element, which together with the security element creates the effect of a color change and / or a polarization effect noticeable to the observer. In a preferred implementation, the display element contains a dark, mainly black background, which can also be made in the form of symbols and / or patterns. In another, also preferred embodiment, the display element may also comprise a linear or circular polarizer.
The present invention also provides a valuable document equipped with a security element or a security system of the kind described. Here, the security element is mainly placed in a window on a valuable document, i.e. on a transparent or at least translucent section of a valuable document or over an aperture made using papermaking technology or by punching. In the context of this description, the term "transparency" refers here to the complete transparency of the material, and "translucent" means transmitting light with a certain degree of transmission, i.e. the material has, in particular, a transmittance of less than 90%, most often in the range of 80-20%. It is only necessary that the light be able to pass on the back of the security element so that it is possible to observe this security element in transmitted light. In particular, it is preferable that the valuable document is flexible so that it is possible to superimpose the security element and the display element by bending or folding the valuable document for self-verification.
Valuable documents in the context of this invention are thus, in particular, banknotes, stocks, identification cards, credit cards, bonds, certificates, vouchers, checks, valuable entry tickets and other documents for which there is a risk of unauthorized reproduction, for example passports and other identification documents. Further, the term “valuable document” covers all such documents. The term “security” means a blank of a valuable document that is not yet in circulation, and this blank can have, in addition to a security element, additional means of authentication, for example, luminescent substances contained in the volume. A security is usually presented in a quasi-infinite form and is subsequently further processed.
According to the method used to determine the authenticity of a security element, security system or valuable document of the type described above, it is checked in transmitted light whether a predetermined color change effect is observed, and the authenticity of the tested element is evaluated depending on the verification results. According to another verification method, a security element is imposed on a dark background formed, if necessary, by a reflection element. Then, information encoded on the security element is read by means of a circular polarizer, and the authenticity of the element being checked is determined depending on the read results.
Further examples of implementation and advantages of the present invention are described below with reference to the drawings, in which, to facilitate their understanding, the scale and proportions are not respected.
figure 1 is a schematic illustration of a banknote on which an overhead hole is located on the outside of the transfer element according to an example implementation of the present invention;
figure 2 - the General structure of the layers of the protection element in cross section according to this invention;
figure 3 is a schematic diagram of a band-stop filter formed from two cholesteric liquid crystal layers and a translucent filter layer;
figure 4 on (a) shows a security element in cross section according to an example implementation of the present invention; in the left row of the drawings (b) - (d) - transmission characteristics of the translucent filter layer, liquid crystal layers and the total transmission of the security element when observed at right angles, and in the right row of the drawings (e) - (g) - the corresponding transmission characteristics when observed under acute angle;
figure 5 on (a) shows in cross section a security element according to another example implementation of the present invention, a (b) - (d) - types of this security element at different viewing angles;
figure 6 - security element according to another example implementation of the present invention;
Fig.7 is a security element depicted in Fig.6, applied to a dark background and containing a circular polarizer for reading encoded information, and
on Fig - a security element similar to that shown in Fig 4 (a), in which one of the cholesteric liquid crystal layers is replaced by a combination of a layer λ / 2 and a cholesteric liquid crystal layer oriented opposite to the original.
Next, a description will be given on the example of a banknote. Figure 1 is a schematic illustration of a banknote 10, which is equipped with a transfer element 12 attached to it according to an example implementation of the present invention. The banknote 10 has a cut through hole 14, which on the front side of the banknote is completely covered by the transfer element 12. Other examples of implementation of the security elements according to the invention can, of course, also be on a plastic-containing document, for example a plastic banknote. Here, the transparent window should preferably be placed on that portion of the document on which nothing is printed. In transmitted light, the transfer element 12 realizes the inverse effect of a color change, in which the color image of the transfer element changes from a short-wave (in this example implementation, from blue) to a longer-wave (in this example implementation, to green) when the protection element is tilted from vertical.
Figure 2 shows a schematic diagram of the structure of the layers of the protection element 20 according to this invention, for example, the transfer element 12, in cross section. On a translucent filter layer 22, for example a colored smooth film of polyethylene terephthalate (PET) with good surface quality, two or more, in general n, light-polarizing layers 24-1, 24-2, ... 24-n, which contain a liquid crystal material, are applied each of which in different implementation examples can exhibit different or in some cases the same properties of light polarization.
Between two adjacent layers or between the first light-polarizing layer 24-1 and the translucent filter layer 22, there may be orienting and / or adhesive layers 26, which serve to ensure uniform orientation of the liquid crystal molecules in the liquid crystal layers or to bond individual layers and to compensate for unevenness of the background surface .
According to the present invention, two liquid crystal layers of layers 24-1, 24-2, ... 24-n contain cholesteric liquid crystal material, and each of them selectively reflects light with a predetermined direction of circular polarization. Here they selectively reflect the light of the first wavelength range in the first reflection direction and the light of the second wavelength range in the second, different direction of reflection. In the following implementation examples, it is always assumed that when light is incident at a right angle, the liquid crystal layers reflect green light, and when light is incident at an acute angle, blue light. It should be understood that such a choice of colors is for illustration only, and that in the context of the present invention, of course, liquid crystal layers with other color characteristics can also be used.
The directions of circular polarization of light reflected by two cholesteric liquid crystal layers can be opposite or the same. In the latter case, there is a λ / 2 layer between two cholesteric liquid crystal layers, which in the corresponding wavelength range changes the direction of circular polarization of light to its opposite. Thus, the entire sequence of layers, containing two cholesteric liquid crystal layers and, if necessary, the λ / 2 layer located between them, reflects light with circular polarization in both directions, and therefore acts as a bandpass filter for transmission for the corresponding wavelength range.
The translucent filter layer may contain a dyed film that simultaneously serves as a substrate for the liquid crystal layers. It can also be formed by a layer of varnish stained with dyes, which is printed, for example, on a transparent and colorless substrate. After applying the security element to a valuable document, the substrate can be removed, for example, in the case where the security element covers a transparent window through the valuable document.
Now, the principle of operation of the band-stop filter formed by two cholesteric liquid crystal layers and a translucent filter layer will be explained in more detail with reference to the drawing of figure 3. Figure 3 shows two cholesteric liquid crystal layers 30 and 32 located one above the other and a translucent filter layer 34, which are shown at intervals between each other to show transmitted and reflected light rays. The direction of polarization of light is indicated on the light propagation vectors by additional arrows. As usual, that circular polarization, in which the circular motion made by the electric field vector from the point of view of the observer towards which the light wave propagates, is directed counterclockwise, is called right circular polarization, and polarization in the opposite direction is called left circular polarization.
Two liquid crystal layers 30 and 32 are formed in such a way that they have the same selective spectrum of reflected color and reflect, for example, green light at a right angle of reflection, and blue light at an acute angle. However, two liquid crystal layers 30 and 32 reflect radiation with different directions of circular polarization. While the first liquid crystal layer 30 in this example implementation reflects the light with right circular polarization, the second liquid crystal layer 32 reflects the light of the corresponding wavelength with left circular polarization. Light with a polarization direction opposite to the one predefined in each case, as well as light with a wavelength outside the range of selective reflection, passes through the liquid crystal layers without significant absorption. The translucent filter layer is colored with dyes so that in the visible spectrum it transmits only blue and green light and absorbs light with a longer wavelength.
If the sequence of layers 30, 32, 34 is irradiated with white light 40, 50, then, as a result, transmitted and reflected light can be described by the following scheme. From the incident white light 40 at a right angle, the green part 41 of the light with right circular polarization will be reflected by the first liquid crystal layer 30, and the green part of the light with left circular polarization and the light of all other wavelengths will pass through it. Then, from the transmitted radiation 42, the second liquid crystal layer 32 reflects the green part of the light 43 with left circular polarization and transmits light of the remaining wavelengths. The green part 44 of the white light spectrum, thus, will be almost completely reflected by the sequence of layers 30, 32, since light is reflected with circular polarization in both directions. Of the radiation 45 remaining after the passage of two liquid crystal layers, which is white light without a green part 44 of the spectrum, the translucent filter layer 34 now passes only the blue part 46 of the radiation. The rest of the white light with other wavelengths will be absorbed.
For white light 50 incident at an acute angle, the wavelength range of the reflected radiation shifts due to physical properties to the range of shorter waves; in this implementation example, the green light changes to blue. Accordingly, the first liquid crystal layer 30 reflects the blue part 51 of the light with right circular polarization, while the blue part of the light with the left circular polarization and light of the remaining wavelengths pass through it. From the transmitted radiation 52, the second liquid crystal layer 32 reflects the blue part 53 of the left circularly polarized light and transmits light of other wavelengths. Thus, in the direction at an acute angle, the blue part 54 of the white light spectrum will be completely reflected by the sequence of layers 30, 32. Of the radiation 55 left after the passage of the two liquid crystal layers, the translucent filter layer 34 now transmits only the green part 56 of the radiation, and part of the white light with other wavelengths will be absorbed.
Thus, in transmitted light, the sequence of layers 30, 32, 34 realizes, in general, the inverse effect of color change, in which for the observer the color image changes from short-wave blue 46 when observed at right angles to longer-wave green 56 when observed at an acute angle. It is quite obvious that the described color change effect in transmitted light is observed regardless of whether the light is incident from above, i.e. from the side of the liquid crystal layers 30, 32, or from below, i.e. from the side of the translucent filter layer 34.
Figure 4 (a) shows the security element 60 according to an example implementation of the present invention, which uses the described principle. Two cholesteric liquid crystal layers 64 and 66 are deposited on the semitransparent film 62 dyed, which have the same light polarization properties as the above liquid crystal layers 32 and 30, i.e. when reflecting at a right angle, they reflect green light, and when observing at an acute angle, they reflect blue light and each of them is circularly polarized in the opposite direction. When the security element 60 is illuminated from the back, which occurs, for example, when observing against the background of daylight 70, the security element, as explained in relation to FIG. 3, transmits only the blue part 72 of daylight when observing at right angles, and when observing under sharp angle - only the green part 74 appears. Thus, the observer sees when tilting the security element 60 the inverse effect of a color change in transmitted light.
4 (b) -4 (g) illustrates the transmission characteristics of the translucent filter layer 62, the liquid crystal layers 64, 66 and the total transmission of the security element 60 when viewed at right angles (left row of figures 4 (b) - (d)) and when observed at an acute angle (right row of figures 4 (e) - (g)).
As shown in the transmission characteristic 80 shown in FIGS. 4 (b) and 4 (e), in the visible part of the spectrum, the color film 62 transmits only blue and green light and absorbs light with a longer wavelength. When observed at right angles, the cholesteric liquid crystal layers 64, 66 serve as a band-stop filter for green light, which reflects the transmission characteristic 82. The combination of the two curves 80 and 82 gives the total transmission characteristic 84 when viewed at right angles of the security element 60, which (transmission), as described above, is described by a significant value only in the blue part of the spectrum.
When viewed at an acute angle, the cholesteric liquid crystal layers 64, 66 form a band-pass filter for blue light, which illustrates the transmission characteristic 86. In turn, the total transmission characteristic 88 is the result of combining curves 80 and 86 and has, as expected, a transmission peak in the green region of the spectrum.
Another example implementation of the present invention is presented in figure 5 (a). The security element 90 has a transparent substrate 92, on which in some areas printed a varnish layer 94, painted with dyes. In other areas, the substrate is provided with a dark background layer 96. Here, the areas coated with a layer of varnish 94, due to their shape or contour, form a pattern; in this example implementation - coat of arms 98.
Two cholesteric liquid crystal layers 100 and 102 are deposited on the varnish layer 94 or on the dark background layer 96, which selectively reflect when viewing at right angles - the light of the first wave range, in the second direction of reflection at an intermediate polar angle - the light of the second shorter wavelength range, and in the third direction of reflection at an acute angle is the light of the third shortest wavelength range.
In this example implementation, the varnish layer 94, which functions as a translucent filter layer, is equipped with two dyes that absorb the light of the first and third wavelength ranges, so that practically only the light of the second - intermediate - wavelength range passes.
When the protection element 90 is illuminated from the rear (item number 104), the observer sees the following image in transmitted light. When observing vertically 106, the observer clearly sees the coat of arms 98, as shown in Fig. 5 (b). In this direction of observation, the liquid crystal layers 100 and 102 reflect the light of the first wavelength range and thus transmit light of the second and third wavelength range. However, since the translucent filter layer 94 absorbs the light of the third wavelength range, and this layer is thus transparent only to light of the second wavelength range, only light of the last (second) range reaches the observer through the liquid crystal layers 100, 102. The portion of the security element having the background layer 96, in contrast to the other portions, remains dark, so that the image of the coat of arms 98 is highlighted with high contrast.
If now the observer tilts the security element 90 relative to the vertical direction so that the incident light 104 enters the liquid crystal layers at an angle (position 108) corresponding to the second direction of reflection, then the emblem 98 disappears, as shown in Fig. 5 (c). It is in this direction of observation that the liquid crystal layers 100, 102 reflect the light of the second wave range transmitted by the translucent filter layer 94. Thus, the portions of the security element having the translucent filter layer 94 and the dark background layer 96 look equally dark, resulting in an image of the coat of arms of the observer does not see.
If the security element 90 is tilted more strongly (position 110), then the pattern 98 appears again, as shown in Fig. 5 (d), since at a sharper angle of incidence, the liquid crystal layers 100, 102 selectively reflect light of only the third wavelength range, and, thus, similarly to the translucent filter layer 94, only the second wavelength range is transmitted.
The security element 120 in another example implementation, shown in Fig.6, contains a translucent filter layer 122, which is applied to the first and second cholesteric liquid crystal layers 124 and 126, which have the same light polarizing properties as the liquid crystal layers 32 and 30. In this example the first cholesteric liquid crystal layer 124 is applied only to some areas in the form of a pattern, for example, in the form of lettering. According to this implementation example, the transmission characteristic of the translucent filter layer 122 is selected so that only blue light passes through it, and green and red light with long wavelengths, on the contrary, are absorbed.
Thus, the portions 128 of the security element 120, covered by both liquid crystal layers 124 and 126, in transmitted light appear blue when viewed at a right angle and, conversely, dark when observed at an acute angle, since the blue light transmitted by the translucent filter layer 122, in this direction is completely absorbed by the liquid crystal layers 124, 126.
However, in the fracture portion 130, in which there is no first liquid crystal layer, blue light appears again at an acute angle, since in this case the second liquid crystal layer 126 reflects the blue light of only one of the two directions of circular polarization. In general, in transmitted light, the initially uniform blue image of the security element 120, when it is tilted relative to the vertical direction, turns into an image having the outline of areas 130 that are not covered by a second liquid crystal layer.
The security element 120 shown in Fig.6, allows you to better visualize the encoded image, which will be explained later with reference to Fig.7. For this verification method, the security element 120 is placed on a dark absorbing background layer 132 to block transmitted light, and this element is observed in reflected light when illuminated from the front. Such a background layer can be implemented, for example, by a separate display element, which, like the security element 120, is located on a valuable document, for example, a banknote, for self-verification.
If you look at the security element 120 with the naked eye, then the first effect is the color change of the second liquid crystal layer 126. In uncoated sections 130, the pattern is observed in each case of the same color, but with a reduced brightness compared to the surrounding sections, since from the overlapping section 128 light 134, 136 with circular polarization of both directions is reflected, and light 138 with circular polarization of only one direction is reflected from uncovered sections 130; in this example implementation, it is light with right circular polarization.
If we now observe the security element 120 through the circular polarizer 140, which transmits light only with the left circular polarization, then the pattern formed by the first liquid crystal layer 124 is highlighted in brightness with high contrast, since the circular polarizer 140 completely absorbs the light with the right circular polarization, reflected a second liquid crystal layer 126. Such a circular polarizer 140 can be formed, for example, by a linear polarizer and a subsequent plate λ / 4. In addition, along with the security element 120 and, if necessary, a dark background layer, it can be on the valuable document as a separate display element for the implementation of self-test.
In all described implementation examples, one of the two cholesteric liquid crystal layers can be replaced by a combination of a λ / 2 layer and a cholesteric liquid crystal layer with an opposite orientation. This is described in the implementation example shown in FIG. 4 (a).
FIG. 8 shows a security element 150 in which the second liquid crystal layer 66 of FIG. 4 (a) is replaced by a combination of a λ / 2 layer 156 and a cholesteric liquid crystal layer 158 oriented opposite to the liquid crystal layer 66, i.e. oriented identically to the liquid crystal layer 154.
The sequence of liquid crystal layers located on the translucent filter layer 152 thus contains two cholesteric liquid crystal layers 154 and 158 with the same light polarizing properties, so that the two layers themselves reflect light with the same circular polarization.
A λ / 2 layer 156 located between the two cholesteric liquid crystal layers 154 and 158 is formed from a nematic liquid crystal material. The effect of the λ / 2 layer 156 and the second cholesteric liquid crystal layer 158 in their sequential arrangement exactly corresponds to the action of the second cholesteric liquid crystal layer 66. In the wavelength range corresponding to each case, the part of the right circularly polarized light transmitted by the first liquid crystal layer 154 will be converted by the layer 156 λ / 2 into the light with left circular polarization and is reflected by the second liquid crystal layer 158. The reflected light will then be converted back to the layer 156 λ / 2 into light with the right th circular polarization and passed through a second liquid crystal layer 154.
The security element 150 shown in FIG. 8 thus has the same reflection and transmission properties as the security element 60 shown in FIG. 4 (a). Due to the presence of an additional layer 156 λ / 2, it is possible to implement new options, for example, the intervals of the patterns can be made directly in the layer λ / 2, and not in the cholesteric liquid crystal layers 154, 158. The layer λ / 2 can also contain two sublayers λ / 4, which can be rotated relative to each other in the plane of the layer to locally attenuate the effect of polarization of light. By choosing a different angle of rotation on other parts of the surface of such an intermediate layer consisting of two λ / 4 sublayers, it is possible, for example, to encode halftone patterns in the security element that appear in the form of grayscale images both when observing in transmitted light and when observing through circular polarizer.
1. The security element for the protection of valuable documents, containing:
a first light-polarizing layer, at least in some areas, containing cholesteric liquid crystal material that selectively reflects light with a predetermined circular polarization and which selectively reflects light of the first wavelength range in the first direction of reflection and light of the second wavelength range in the second, different from the first direction of reflection
a second light-polarizing layer, present in at least some areas, which selectively reflects circularly polarized light opposite to the predetermined circular polarization, and which selectively reflects light of the first and second wavelength ranges in the first and second reflection directions, respectively, and
a translucent filter layer on which the first and second light-polarizing layers are located one above the other, the filter layer at least partially absorbing the visible light of the spectrum and transmitting light of the first and / or second wavelength range.
2. The security element according to claim 1, characterized in that the second light-polarizing layer is formed from a cholesteric liquid crystal material and selectively reflects light with circular polarization opposite to a predetermined circular polarization.
3. The security element according to claim 1, characterized in that the second light-polarizing layer is formed of two sublayers, the first sublayer is formed of a cholesteric liquid crystal material and selectively reflects light with a predetermined circular polarization, and the second sublayer is located between the first sublayer and the first light-polarizing layer, forms a layer λ / 2.
4. The security element according to claim 3, characterized in that the λ / 2 layer is formed of a nematic liquid crystal material.
5. The security element according to claim 3, characterized in that the λ / 2 layer is formed of a plurality of sublayers located one above the other and in some areas rotated in the plane of the layer relative to each other.
6. The security element according to claim 5, characterized in that the plurality of sublayers are formed by two layers λ / 4.
7. The security element according to claim 1, characterized in that the first and second light-polarizing layers selectively reflect the light of the third wavelength range in the third direction of reflection, and the translucent filter layer at least partially absorbs the visible light of the spectrum and transmits light of the first, and / or second, and / or third wavelength range.
8. The security element according to claim 1, characterized in that the first and second light-polarizing layers reflect the light of the visible spectrum in all directions of reflection.
9. The security element according to claim 1, characterized in that the first and second light-polarizing layers reflect the light of the invisible range of the spectrum in at least one of the directions of reflection.
10. The security element according to claim 1, characterized in that the first and second and, if necessary, the third direction of reflection differ from each other by a polar angle of at least 20 ° relative to the normal to the surface of the light-polarizing layers.
11. The security element according to claim 1, characterized in that the first and second direction of reflection differ from each other by a polar angle of at least 40 ° relative to the normal to the surface of the light-polarizing layers.
12. The security element according to claim 1, characterized in that the first and / or second light-polarizing layer and / or, if necessary, the first and / or second sublayer of the second light-polarizing layer are made in the form of symbols and / or patterns.
13. The security element according to claim 1, characterized in that it has additional light-polarizing layers containing nematic or cholesteric liquid crystal material.
14. The security element according to claim 1, characterized in that at least one of the light-polarizing layers containing cholesteric liquid crystal material and / or, if necessary, at least one layer containing a nematic liquid crystal material, are implemented in the form of pigments embedded in a bonding matrix .
15. The security element according to 14, characterized in that the first and second light-polarizing layers that reflect light with opposite circular polarizations are formed from a cholesteric liquid crystal material and are implemented as pigments, wherein a mixture of equal parts of the pigments of the first and second light-polarizing layer is embedded in a binder matrix, so that the first and second light polarizing layers can be applied as a single layer.
16. The security element according to claim 1, characterized in that the translucent filter layer transmits light between the first and second and, if necessary, third wave ranges and absorbs visible light outside these wave ranges.
17. The security element according to claim 1, characterized in that the translucent filter layer allows only the first, and / or only the second, and / or only the third wavelength range to pass through and absorbs visible light outside the first and / or second, and / or third wave range.
18. The security element according to claim 1, characterized in that the translucent filter layer is formed by a varnish layer or a film dyed with one or more dyes.
19. The security element according to claim 1, characterized in that the translucent filter layer is made in the form of characters and / or patterns.
20. The security element according to claim 1, characterized in that the light-polarizing layers and, if necessary, a translucent filter layer are deposited on the base, and the base is preferably formed of paper or plastic.
21. The security element according to claim 1, characterized in that between the adjacent light-polarizing layers and / or between the light-polarizing layer and the translucent filter layer there are orienting and / or adhesive layers designed to ensure uniform orientation of the liquid crystal layers.
22. The security element according to claim 1, characterized in that the security element forms a label or transfer element.
23. A method of manufacturing a security element according to any one of claims 1 to 22, in which the first light-polarizing layer containing cholesteric liquid crystal material, and a second light-polarizing layer that contains at least one layer or sublayer containing cholesteric liquid crystal material, is applied one after the other to translucent filter layer.
24. The method according to item 23, wherein the one or more liquid crystal layers are applied, in particular printed, on a substrate.
25. The method according to paragraph 24, wherein after applying to the substrate, the liquid crystal layers are checked for suitability for further processing.
26. The method according to item 23 or 24, characterized in that two or more liquid crystal layers are applied one after another on the same substrate.
27. The method according to any one of paragraphs.23-25, characterized in that the liquid crystal layers present on the substrate are layered on a translucent filter layer or on an additional liquid crystal layer.
28. The method according to p. 27, characterized in that after gluing the substrate is removed, in particular by means of separation layers or using a laminating adhesive, the adhesion of which to the substrate is less than its adhesion to the liquid crystal layer, or by means of an auxiliary layer, which is applied to the entire surface of the liquid crystal layer and whose adhesion to the substrate is less than its adhesion to the liquid crystal layer.
29. The method according to p, characterized in that the auxiliary layer is formed by a layer of UV varnish.
30. The method according to any one of paragraphs.23-25, wherein the cholesteric liquid crystal layers are formed by combining a system of nematic liquid crystals with a piezoelectric crystal with torsional vibration.
31. The method according to p. 30, characterized in that the first and second cholesteric liquid crystal layers, reflecting light with circular polarization of opposite directions, are formed by combining a system of nematic liquid crystals with a coordinated first and second piezoelectric crystals with torsional vibration, so that the liquid crystals of the first and the second layer are arranged with the formation of mirror-image spiral structures.
32. The method according to any one of paragraphs.23-25, characterized in that the λ / 2 sublayer of the second light-polarizing layer is formed from a nematic crystalline material.
33. A security system for a security, security documents and similar products, comprising:
a security element according to any one of claims 1 to 22 or a security element made according to any one of claims 23 to 32, and
a separate display element, which, when combined with a security element, makes the color change effect and / or polarization effect noticeable to the observer.
34. The security system according to p. 33, wherein the display element contains a dark, preferably black background.
35. The protection system according to clause 34, wherein the background is made in the form of symbols and / or drawings.
36. The protection system according to paragraphs 33 and 34 or 35, characterized in that the display element further comprises a linear or circular polarizer.
37. A valuable document, such as a banknote, check, certificate, identification card or similar document, equipped with a security element according to any one of claims 1 to 22 or a security element made according to any one of claims 23-32, or a security system according to any one of claims .33-36.
38. Valuable document according to clause 37, wherein the security element is placed in a window on a valuable document.
39. The valuable document according to clause 37, wherein the valuable document is flexible, so that the security element and the display element can be superimposed upon folding or folding a valuable document for the implementation of self-test.
40. A method for verifying the authenticity of a security element according to any one of claims 1 to 22 or a security element manufactured according to any one of claims 23-32, or a valuable document according to any one of claims 37 to 39, characterized in that they are checked in transmitted light, is there a predetermined color change effect, and based on the result of the check, the authenticity of the item being checked is evaluated.
41. A method for verifying the authenticity of a security element according to any one of claims 1 to 22 or a security element manufactured according to any one of claims 23-32, or a valuable document according to any one of claims 37-39, characterized in that the security element is placed on a dark a background formed, if necessary, by a display element, wherein the information encoded in the security element is read by means of a circular polarizer and the authenticity of the element being checked is evaluated based on the read results.
42. The use of a security element according to one of claims 1 to 22 or a security element made according to one of claims 23-32, or a security system according to one of claims 33-36 for protection against counterfeiting of valuable items, for example, goods of famous brands or valuable documents.
RU2006141521/12A 2004-04-30 2005-04-29 Protection component and method of its manufacturing RU2364517C2 (en)
RU2006141521A RU2006141521A (en) 2008-06-10
RU2364517C2 true RU2364517C2 (en) 2009-08-20
RU2006141521/12A RU2364517C2 (en) 2004-04-30 2005-04-29 Protection component and method of its manufacturing
US8168080B2 (en) * 2006-08-09 2012-05-01 Nhk Spring Co., Ltd. Identifying medium, identifying medium manufacturing method, article, and identifying medium identifying method
JP6286699B2 (en) * 2013-05-01 2018-03-07 シクパ ホルディング ソシエテ アノニムＳｉｃｐａ Ｈｏｌｄｉｎｇ Ｓａ Security elements exhibiting dynamic visual movement
WO2015005825A1 (en) 2013-07-08 2015-01-15 Федеральное Государственное Унитарное Предприятие "Гознак" (Фгуп "Гознак") Paper-based or polymer-based multi-layer document and method for determining authenticity thereof