RU2310924C2 - Method of protection of securities due to application of holographic marks - Google Patents

Abstract

FIELD: protection against falsification of securities.

SUBSTANCE: separating, protecting and working layers are applied onto flexible base. Hologram of mark is formed onto surface of working layer. Mark is fixed in form of relief-phase hologram. Reflecting and gluing layers are applied and hologram of mark is transferred onto surface of security to be protected. Then flexible base is removed. Working layer is made of material with photo-thermoplastic properties. Hologram of mark is formed of separate fragments. Formation of mark and registration of relied-phase hologram of mark are partially coincided in time.

EFFECT: improved protection of hologram and securities from falsification.

5 cl, 4 dwg

Description

This invention relates to the field of issuing securities for various purposes, banking, mainly to the field of protection of securities and documents from possible falsification, identification of the authenticity of protected documents, as well as indications of unauthorized access. Also, the invention can be used in various fields of printing and advertising.

A known method of protecting securities by applying holographic marks [1], formed by embossing, which consists in forming a hologram of the mark, registering the primary hologram of the mark, copying it onto the working layer, applying an adhesive layer to the back of the mark and sticking the mark on the document to be protected. The primary hologram is copied onto the working layer by recording the secondary hologram on positive photoresistive material, etching the photoresistive material, metallizing it, manufacturing a copy matrix from the etched secondary hologram and transferring it to the working layer by mechanical deformation (stamping) of the working layer by means of a copy matrix. In this case, the working layer is made of a flexible base (for example, mylar ribbon), on which a reflective layer is applied before copying the primary hologram of the label. After contact deformation of the working layer, which ensures the fixation of the hologram of the mark, an adhesive layer is applied to its back side (flexible base), which ensures that the hologram of the mark contacts the surface of the security to be protected when gluing the mark.

There is also known a method of protecting securities by applying holographic marks [2], which consists in a similar method described above for forming a hologram of a mark, fixing it on the working layer in the form of a relief phase hologram and transferring the holographic mark to the protected document by contacting the adhesive coating with the surface of the protected document . In this case, prior to fixing the relief phase hologram, a separation layer (wax layer), a protective lacquer layer (on the surface of which the relief phase hologram of the mark is fixed) and a reflective layer are sequentially applied to a flexible dielectric base (for example, lavsan tape), and after fixing the mark, an adhesive layer is applied layer. After transferring the holographic mark to the document to be protected, the flexible base is removed along the separation layer, changing its physical parameters (for example, heating).

The disadvantages of the known methods are:

- the complexity of the technology for the formation and fixation of the hologram tags caused by a multi-stage process of manufacturing and copying the hologram, including technological operations of various kinds (photochemical processing, etching, multiple copying and transfer of holograms from one carrier to another);

- a low degree of protection due to the potential for copying a phase-relief hologram;

- low speed due to the multi-stage process of forming and fixing a holographic mark;

- the impossibility (within the framework of a single technological process of forming and fixing a hologram of a tag) of identifying each individual tag.

There is a method of protecting securities by applying holographic marks [3], which consists in sequentially applying a separating, protective and working layers on a flexible base, forming a hologram of the mark on the surface of the working layer, fixing it in the form of a relief-phase hologram, applying reflective and adhesive layers, transferring the hologram of the label to the surface of the security to be protected and removing the flexible base, the working layer being made of a material with photothermoplastic properties, and the fixation of the relief-phase holograph we carried out directly after the formation of the hologram label.

The disadvantages of the known method closest to the invention and selected by the authors for the prototype are:

- a relatively low degree of protection of the hologram from possible reading, caused by the possibility of restoring the geometric relief and copying it during the chemical removal of the protective and working layers (applying a masking layer according to claim 2 of the prototype method, which is similar in physical and chemical parameters to the working layer, allows partially solving this task, however, in the prototype method, the application of a reflective coating with a high reflection coefficient, providing high consumer properties of the fixed hologram, chemical sky isolates the masking and working layers from each other, making it possible to remove the protective and working layers by means of organic solvents without damaging the relief, i.e. copy the hologram of the tag);

- the unsolved problem of identifying a separately considered holographic mark at the level of a technical solution;

- low speed, due to the consistent nature of the formation of the hologram labels on the surface of the working layer and the fixation of the relief-phase hologram.

The aim of the proposed method is to increase the degree of protection of securities from possible fakes.

This goal is achieved due to the fact that in the known method, which consists in sequentially applying a separating, protective and working layers onto a flexible base, forming a hologram of the mark on the surface of the working layer, fixing it in the form of a relief phase hologram, applying reflective and adhesive layers, transferring holograms of the mark on the surface of the security to be protected and removal of the flexible base, the working layer being made of material with photothermoplastic properties, the hologram of the mark is formed from separate fragments entov, the formation and registration of the relief phase hologram of the label is partially combined in time.

This goal is achieved due to the fact that fragments of the hologram of the label partially spatially overlap in the area of formation of the hologram.

This goal is achieved due to the fact that the fragments of the image of the hologram of the label are divided during formation into two groups: unchanged for holographic labels and individual (identification), which are different for each label.

This goal is achieved due to the fact that the reflective layer is made partially transparent with a reflection coefficient less than 1.

This goal is achieved due to the fact that before applying the adhesive layer on the reflective layer, a mask layer is applied.

Figure 1 shows the manufacturing diagram of a holographic label according to the proposed method, where the following notation is introduced:

1 - original tag;

2 - laser;

3 - block forming a hologram;

4 - holographic label;

5 - hologram fixing device;

6 - high voltage voltage source with an electrode 6a;

7 - heat conduit;

8 - a direct current source;

9 - key cascades;

10 - shutter;

11 - time slider;

12 - counter of the number of holographic marks;

13 - space-time light modulator with a control unit.

Figure 2 shows a view of a holographic mark and the following notation is introduced:

14 - an invariable fragment of a hologram of a label;

15 - fragment, individual for each holographic label;

16 - area overlap fragments.

Figure 3 shows the timing diagram of the processes of formation and fixation of the hologram tags for the prototype method (figure 3, a) and the proposed method (figure 3, b). Letters A, B indicate cyclograms of the processes of formation and fixation of the hologram of the label. The letter B marks the sequence diagram of the input-output process of sequentially produced holographic marks from the zone of formation and fixation of the hologram.

Figure 4 shows a generalized diagram of the technological process of manufacturing and applying a holographic mark and the structure of the manufactured mark in the corresponding operation, where the following notation is introduced:

17 - blocks for applying dielectric coatings (watering machines);

18 - block applying a reflective layer;

19 - label transfer unit (stamp);

20 - a separation layer;

21 - a protective layer;

22 - working layer;

23 - reflective layer;

24 - adhesive layer;

25 - substrate (flexible dielectric base);

26 - masking layer;

27 - relief phase hologram;

28 - surface of the protected document 29.

The essence of the proposed method is as follows.

Make the original label 1, the hologram of which must be applied to the surface 28 of the protected document (security 29). It can be a three-dimensional model, flat banners or a combination of flat and three-dimensional components that together form the required original label (a set of fragments). Moreover, the manufacture of the original label 1 from several fragments allows you to vary the structure of the generated holographic labels.

As an example, we consider possible options for the formation of holographic labels (shown in figure 2).

The fragment 14, unchanged for the whole set of generated holographic labels, for example, the trademark of a company, the fragment 14 unchanged for a certain group of generated holographic labels, and, for example, the code of the protected document 14. Figure 2a shows a view of two such holographic labels having unchanged a fragment of a hologram of a label - a trademark and different codes of protected documents - fragments A1 and B1.

Fragment 14, which is unchanged for the entire set of generated holographic labels, for example, a company’s trademark, fragment 14 unchanged for a specific group of generated holographic labels, and, for example, the code of the protected document, fragment 15 changing from hologram to hologram, for example, hologram serial number. Figure 2b shows a view of two such sequentially produced holographic tags having an unchanged fragment of a hologram of a label - a trademark, a code of a protected document (a fragment of a hologram of a label A1) and an original fragment for each individually generated and fixed hologram of a hologram (21 , 22).

These fragments of holograms can be both spatially separated, disjoint, as shown in Fig. 2, a and 2, b, and partially spatially coincide, forming an interferogram in the intersection, as shown in Fig. 2, c. This figure shows two options for the intersection of various fragments of the generated hologram. Moreover, since in the region of the spatial intersection of the fragments of the generated hologram, one of the fragments is individual for each individual hologram, the region of the spatial intersection will also be an interference pattern that varies from hologram to hologram. Of particular interest is the option presented in the second picture of figure 2, c. In this case, an individual fragment for each hologram - number (T22) defines the boundary of fragment 15 (its shape). The inner region of this fragment is common for the hologram fragments 14 and 15. Moreover, after fixing the hologram of the mark during its visualization, in contrast to the known cases of numbering of holographic marks, the internal filling of the number will be a rainbow-like interference pattern, generally changing from label to label, which further complicates the process of copying a hologram for fake purposes.

Consider the formation of holographic labels in this way. The label (before the implementation of the process of applying labels to the protected document) is a multilayer structure, which is formed as follows.

Prior to the formation of the hologram, a separating, protective and working layers are sequentially applied to a flexible dielectric substrate 25 made, for example, from an Mylar ribbon. The separation layer 20 is a film structure, under the influence of external physical factors capable of changing its adhesive properties. The influencing factors may be heating and mechanical stresses along the interface between the separation layer and the substrate. This provides the ability to remove a flexible base - substrate after transferring a holographic mark to the surface of the protected document. One embodiment of the separation layer is a thin wax layer. The protective layer (21) is a dielectric film structure that protects the outer surface of the holographic mark from contact with the environment after transferring the mark to the surface of the document to be protected. It is performed, for example, on the basis of a lacquer coating with predetermined physicochemical properties that ensure the holographic mark is resistant to mechanical and chemical influences. Varying the chemical composition of the material of the protective coating allows both high chemical resistance and the desired basic color gamut of the holographic mark. The working layer (22) serves to fix the relief-phase hologram of the mark on its surface. This layer is made of a photosensitive thermoplastic material applied over a protective layer.

The application of the aforementioned layers to the substrate is ensured by sequentially passing the flexible substrate through the irrigation machines 17. The layer material is applied to the substrate from the solution.

The process of forming a hologram label similar to that used in the prototype method and consists in the following. Before the formation of the hologram of the label, an electrostatic charge is applied to the surface of the working layer, causing the appearance of an electrostatic field. Beams of coherent radiation forming a hologram of the label cause local changes in the electrostatic field intensity at each point on the surface of the working layer, proportional to the radiation intensity, forming a potential relief for which the spatial distribution of the surface electrostatic charge is proportional to the distribution of the radiation intensity forming the hologram of the label. Under thermal exposure, due to the thermoplastic properties of the working layer, its material acquires fluidity, an inhomogeneous electrostatic charge leads to the appearance of surface forces that transform the potential relief into a geometric relief, the depth of which is proportional to the formed local distribution of radiation intensity. When the thermal effect ceases, the working layer solidifies, fixing the formed geometric relief that carries information about the hologram of the label in the form of a relief phase hologram. Thus, the operation of fixing the relief-phase hologram is carried out, carrying out surface deformation of the working layer without mechanical contact, by performing operations on the surface of the working layer to form a hologram of the mark in the form of a potential relief and converting it into a geometric relief during thermal exposure.

The operations of forming a hologram of a label (forming a potential relief on the surface of the working layer) and fixing a relief-phase hologram (converting a potential relief to geometric and fixing a geometric relief) in the prototype method are carried out sequentially (see time diagrams A and B in Fig. 3, a ), which leads to a decrease in the diffraction efficiency of the recorded hologram due to the partial spreading of the potential relief (caused by the finite conductivity of the working layer) and, therefore, to lower the quality of the holographic mark. In the proposed method, these processes partially coincide in time (see time diagrams A and B in Fig. 3, b). In this case, in addition to reducing the time of formation of the hologram of the label and its fixation, which improves the speed of the proposed method, the quality of the generated hologram increases. This can be explained as follows. The process of forming a hologram on the surface of the working layer leads to the appearance of a surface gradient of the electrostatic field, i.e. to the appearance of a potential relief. When the material of the working layer is softened during thermal exposure, the thermoplastic material acquires fluidity, i.e. acquires some properties of a liquid. If during the heat exposure continue the process of exposure of the working layer by radiation, i.e. to continue the process of forming the hologram of the label, then, due to the photosensitivity of the material of the working layer, the process of forming the potential relief will continue, which will lead to an increase in the depth of the geometric relief, and consequently, to an increase in the diffraction efficiency of the fixed relief-phase hologram.

The formation of the hologram of the label and its fixation in the form of a relief-phase hologram is carried out directly on each individual label, which allows to ensure the identifiability of each label by introducing changes to the original label (for example, numbering them).

After fixing the relief-phase hologram, a reflective layer is applied to the surface of the working layer. The reflective layer 23 increases the diffraction efficiency of the fixed hologram, increasing its consumer properties. In addition, the implementation of the reflective layer is partially transparent, with a reflection coefficient less than 1, increases the protective properties of the holographic mark, reducing the possibility of high-quality copying and complicating the fake process.

This can be explained as follows. When applying a reflective layer to dielectric coatings, the reflection coefficient depends on both the material properties of the reflective layer and its thickness. Therefore, when applying a thin reflective layer having residual transparency, this layer due to the presence of micropores is not insulating (in the sense of chemical neutrality), providing chemical contact and chemical interaction of the adjacent layers of the holographic mark. Under this condition, faking a holographic mark by unauthorized copying is difficult, since to copy a fixed phase-hologram, it is necessary to remove the upper protective layer 21, as well as the working layer 22, in order to access the hologram 27 itself. Due to the thinness of the layers (units μm ) this can only be done chemically by sequentially dissolving the layers 21 and 22. If the reflective layer 23 is thin, then when the layer 22 is dissolved, the solvent particles penetrate through cut the layer 23 and partially dissolve the underlying layers, which will lead to a distortion of the geometric relief (due to the "erosion" of the fine high-frequency structure of the hologram) and, therefore, to the impossibility of copying the hologram with high quality.

On top of the reflective layer, an adhesive layer 24 is applied to the formed holographic mark. This layer is applied after the reflective layer and the formed holographic mark is fixed on the surface of the document to be protected. The adhesive layer is made of glue having good adhesive properties to the label layers in contact with it and to the surface of the document to be protected (paper, plastic).

To increase the degree of protection of the holographic mark against counterfeiting between the reflective and adhesive layers, an additional masking layer 26 is made of a photosensitive thermoplastic material similar in physical and chemical parameters to the material of the working layer 22. After applying this layer, the fixed phase-relief hologram is inside the “sandwich” structures "of two layers identical in physicochemical parameters, at the interface of which a reflective layer is deposited. The residual porosity of the reflective layer, provided by its small thickness with a reflection coefficient less than 1, further increases the adhesion of the working (22) and masking (26) layers. Moreover, this structure does not allow the contact copies of the fixed holograms to be removed when one of the layers is destroyed in some way, for example by chemical dissolution, due to the partial dissolution of the underlying layer 26 by solvent particles penetrating the pores of the reflecting layer 23, which will lead to a distortion of the geometric relief ( due to the “erosion” of the fine high-frequency structure of the hologram).

The proposed technology for the formation and application of holographic labels on protected securities does not interfere with the introduction of various additives into the applied layers and the application of security signs using other technologies (microprinting, encoding, etc.), which increases the number of degrees of protection.

Consider an example of the implementation of the proposed method in the device.

The original mark 1 is illuminated by the coherent radiation of the laser 2 and, using the hologram forming unit 3, a hologram of the mark of the desired type, for example, rainbow, is formed on the surface of the holographic mark 4. To perform a hologram of a tag from several fragments, the original tag, in addition to the volumetric model itself or transparency, contains a spatio-temporal light modulator 13 with a control unit and a counter for the number of holographic tags 12. A counter 12, which is, for example, a counter with an optical input that works, for example, from the radiation of the laser 2 at the time of opening the shutter 10, generates at its output a code for the current hologram of the label, which is transmitted to the control unit of the spatio-temporal light modulator 12. As a result, the space-time light modulator modulates the coherent radiation passing through it, forming a changing fragment of the hologram, for example, the current label number 15 (see Fig. 2). For the purposes of partial spatial combination of various fragments of the generated hologram, a beam splitter is used. The hologram fixing device 5 is a combination of the following nodes and blocks. The generated holographic mark 4 is brought into contact with the heat conductor 7. By means of a high voltage voltage source 6, a potential difference is created in the discharge gap between the electrode 6a and the heat conductor 7, as a result of which a uniform electrostatic charge is applied to the surface of the formed holographic mark 4. By exposing the holographic mark through the open shutter 10, the original mark 1 and the hologram forming unit 3 by laser radiation 2 form a potential relief on the surface of the working layer. To convert the potential relief into a geometrical one, when a thermal effect is applied to the working layer, a direct current source 8 is used, loaded on a heat conductor 7, which is a conductive layer on a massive dielectric base, which is in thermal and mechanical contact with the back of the label.

The synchronization of the illumination processes of the original label, the formation of its hologram, applying an electrostatic charge, converting the potential relief into a geometric one (manifestation of a hologram) and fixing the hologram is carried out by means of a time slider 11 with output keys 9, a shutter 10 (for gating laser radiation 2) and a tag counter 12. After removing the heat load, the working layer of the holographic mark hardens, fixing the geometric relief. In this case, the hologram of the mark is fixed on the surface of the working layer in the form of a relief-phase hologram.

The reflective layer 23 is applied to the working layer 22 in the unit for applying the reflective layer 18 (installation for spraying conductive metal coatings, for example, by evaporation in vacuum). Providing the required reflection coefficient is carried out by selecting the appropriate spraying mode, for example, the speed of the marks through the active zone of the spraying unit. Various metals (aluminum, silver, molybdenum, etc.) can be used as materials for applying the reflective layer, which makes it possible to vary the color gamut of holographic labels and their physicochemical properties. The application of separation 20, protective 21, worker 22, adhesive 24 and masking 26 layers is carried out in the application blocks of dielectric coatings 17 using standard watering machines. The structure of the label in the manufacturing process is shown in Fig.4.

After applying the adhesive layer, a holographic mark is applied to the surface of the document to be protected. To do this, it is placed between the label transfer unit 19 (with a flat stamp with the contour determined by the shape of the mark) and the surface of the document 29 to be protected. Positioning is carried out by means of a precision tape drive into which made tags are inserted sequentially on a flexible base (perforated for this case) . By means of a stamp, the adhesive layer is brought into mechanical contact with the surface of the document to be protected and glued to it. The mechanism of the gluing process may be different. In particular, the adhesive layer may be a hot melt adhesive, then gluing is carried out by heating the label to a temperature higher than the softening temperature of the hot melt adhesive. At the same time (or after) the physical properties of the separation layer are changed, for example, heating it to a temperature above the softening temperature, which ensures the separation of the flexible base substrate. At the end of this operation, the generated holographic mark is fixed on the surface of the protected document.

The main advantages of the method is to increase the degree of security of the hologram, which is ensured by the direct formation of the hologram as a set of individual fragments on the surface of each individual label in real time and by partial combination of the processes of formation and fixation of the hologram of the label in time. The manufacture of a reflective layer with a reflection coefficient less than 1, the presence of dielectric layers that protect the fixed relief-phase hologram from mechanical influences, does not allow the hologram to be copied and its accidental mechanical damage. An additional positive effect is the increase in performance caused by the partial combination in time of a number of operations of the proposed method.

Information sources

1. Optical holography. / Ed. G. Culfield, vol. 2, M., Mir, 1982, p. 412-413.

2. UK patent No. 2211760, CL B44f 1/12, 1987.

3. Russian patent No. 2035315, MKI6 B44f 1/12, 1/14, B41L 13/00, B41m 3/14, G03h 1/00, G09f 19/00 - prototype.

Claims (5)

1. A method of protecting securities by applying holographic marks, which consists in sequentially applying a separation, protective and working layers on a flexible base, forming a hologram of the mark on the surface of the working layer, fixing it in the form of a relief phase hologram, applying reflective and adhesive layers, transferring the hologram marks on the surface of the security to be protected and removal of the flexible base, the working layer being made of a material with photothermoplastic properties, characterized in that the hologram of the mark is formed removed from the individual fragments, the formation of relief-and registration phase hologram label partially aligned in time. 2. The method according to claim 1, characterized in that the fragments of the hologram label partially spatially overlap in the area of formation of the hologram. 3. The method according to claim 1 or 2, characterized in that the image fragments of the hologram of the label are divided into two groups when forming: invariable, for holographic labels, and individual (identification), different for each label. 4. The method according to claim 1, characterized in that the reflective layer is made partially transparent with a reflection coefficient less than 1. 5. The method according to claim 1, characterized in that before applying the adhesive layer on the reflective layer, a mask layer is applied.

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