RU2224289C2 - Protective device - Google Patents

Abstract

FIELD: means for protecting securities and other valuables against unauthorized reproduction or counterfeit. SUBSTANCE: protective device has holographic structure that generates optically variable effects and is built of at least two sections. Its illumination with white light produces image of two holographic elements disposed on or near plane adjacent to or aligned with that of device. Under coherent light sections produce latent images in the form of characters whose planes are spaced apart from physical plane of device; latent images are recovered at different angles to normal of device supporting base causing spatial division of latent images into their display planes. Latent images are not visible when illuminated by white light. EFFECT: enhanced reliability of valuables protection. 20 cl, 13 dwg

Description

 The invention relates to a protective device designed to protect documents and other valuable products from illegal reproduction, counterfeiting, etc.

 Many protective devices are based on the use of structures that generate optically variable effects that generate holograms and the like, since they are difficult to manufacture. Examples of such holographic structures and methods for their manufacture can be found in EP-A-0548142, EP-A-0632767 and WO-A-99/59036, owned by De La Rue International Limited, and the ideas set forth therein, as well as other patents referenced in these documents are incorporated into this description by reference. WO-A-92/094444, which also defines the state of the art, discloses a method for creating an image detail of an optical microstructure providing enhanced security stability and ease of authentication for visual verification of banknote authenticity. Certain visual protective devices based on a diffraction grating already exist, for example, described in EP-A-0105099, which describes a protective device that demonstrates the effect of apparent movement, consisting of sections of a flat diffraction grating oriented in different directions along the path, each of which creates a diffraction incident light beam in one specific direction, although it should be noted that this device is based on purely diffraction gratings and each section, being a purely diffraction grating oh, they are not able to form a hidden part in the form of a focused out-of-plane image in coherent lighting.

 With regard to previous holographic security structures that are read in hardware or observed in coherent illumination, EP-A-0548142 describes how to use an hologram to create an out-of-plane image for authentication, although you should pay attention to the fact that in this case it was provided that the hardware the readable structure is completely hidden from visual observation by the observer of the hologram and in reality consists of combined weak diffraction gratings that do not form focused in non-flat image. DE-A-3840037 shows an example of a visual security hologram containing a combined complementary laser transmitting hologram designed to form an out-of-plane image to be detected in the light of a laser using reading equipment or a visualizer and not recognized under normal lighting.

 There is a continuing need to increase the security of such protective devices while ensuring ease of verification of their authenticity.

 US-A-5825478 describes a system and method for determining which of a set of visually indistinguishable objects is marked with a hidden indicator, which system and method provide that part of the surface of each object of the first type is equipped with a hidden holographic indicator, which is exposed for observation, but detected only when illumination with coherent reference light of a specific wavelength.

 According to the present invention, the security device comprises a holographic structure that generates optically variable effects, comprising at least two separate sections that create, when illuminated with white light, an optically variable image consisting of at least two specific graphic elements located in or near the image plane, coinciding with or adjacent to the plane of the device, and which, under coherent illumination, create at least two separate latent images in the form characters, the image plane which are arranged at a distance from the physical plane of the device, wherein latent images reconstructed at different angles to the normal bases supporting device, so that the latent images are spatially separated on their image plane, and the latent image is almost invisible under white light illumination.

 By a holographic structure generating optically variable effects, in this case, we mean any diffraction device capable of forming the first visual localized graphic image near the physical plane of the device, subject to visual observation, as well as forming an out-of-plane hidden laser-controlled image (instead of the more common iris ) to be observed in coherent light. Such a structure can be created only by holographic means or by computer simulation and direct recording of the desired interference picture of the structure, which is a slower and much more time-consuming way to create such an element.

 Especially useful is this kind of holographic structure that generates an optically variable effect, which provides directions for reproducing a visual optically variable image, creating the effect of an apparent movement when the device is rotated around a certain axis.

 This new holographic security device contains a structure that creates when illuminated with white light, at least two specific localized optically variable graphic images in the image plane adjacent to the structure, and with coherent illumination, at least two latent images away from the plane images located at different angles to the normal of the base supporting the device. The distance between latent images is usually about half their size. Thus, in normal white light, the observer sees a conventional optically variable image, such as a hologram or diffraction effect, consisting of at least two or more parts, but in coherent lighting, such as laser light, the observer sees two or more different hidden images .

 These latent images preferably take the form of graphic elements, characters or alphanumeric characters, which are usually associated with the product or document for which a protective device is provided. Visual optically variable images are also preferably in the form of small defined shapes or characters.

 In a preferred case, latent images restored by coherent illumination of the device with a laser can be observed with the naked eye, although such restoration can also be carried out at a wavelength outside the visible range provided for hardware detection.

 According to one embodiment, the structure generating the optically variable effects, when illuminated with white light, forms two or more graphic images or figures that create the illusion of movement when the device is rotated. In this regard, one should distinguish between an apparent three-dimensional holographic phenomenon, etc. with a motion effect, for example, a transverse displacement due to the difference in diffraction angles between the elements.

 An advantage of this embodiment is that each element of a holographic structure generating an optical variable effect is made in the form of a single structure, the maximum transverse dimension of which usually does not exceed 1.5 mm. Preferably, the maximum transverse dimension is not less than 0.5 mm and, most preferably, is in the range 0.5-0.75 mm, the device comprising at least two such elements reproducing different latent images in different directions.

 Recovery of latent images can be improved by providing several pairs or sets (of three or more) of similar sections, each element of a pair or set being designed to form the same latent image with coherent illumination as the other (s) element (s) of a pair or set . In this case, the individual elements should be so close to each other that they can be simultaneously illuminated by a coherent beam and, thus, completely restore the hidden message. Typically, the diameter of a portion illuminated by a laser beam generated by a laser pointer or similar device is about 2 or 3 mm.

 To increase the degree of protection by increasing the complexity of the device as a whole and to hide the presence of this new holographic structure generating optically variable effects, one structure generating optically variable effects can be placed in a set of additional structures generating optically variable effects intended to create only images or effects visible in white light, and one and additional structures that generate optically variable effects, being illuminated by white light, when Rothe bases act together, creating the effect of a moving image. Thus, an unskilled observer will observe the effect of a moving image when illuminated with white light, and only by illuminating the correct set of structures generating optically variable effects with coherent light can he detect hidden images. Under normal white light, it will not detect differences in structures and the presence of latent images in the device.

 According to another embodiment, sections of the structure generating optically variable effects are made in the form of regions separated from each other.

 As in the first embodiment, in order to improve the recovery of latent images, it is possible to provide pairs or sets of such areas, each of which usually has a maximum transverse dimension not exceeding 1.5 mm. Preferably, the maximum transverse dimension is not less than 0.5 mm and, most preferably, is in the range of 0.5-0.75 mm.

 This second embodiment is particularly useful when the structure, when illuminated with white light, creates an image moving when the device is rotated. This combination of details is especially difficult to reproduce, but it is not difficult to verify its authenticity.

 The holographic structure that generates optically variable effects, capable of forming hidden out-of-plane images, has the form of a holographic structure containing two image planes, the plane of the visual image observed in white light, and the plane of the out-of-plane image observed when the device is illuminated with coherent light.

 The geometric shapes of these sections separated from each other, preferably graphic elements, must be focused in close proximity to the plane of the hologram surface, while the information encoded in these sections is focused (or displayed) at a sufficient distance from this plane of the surface and therefore to observe and Thus, to control it, coherent lighting is required, for example, using a laser. Each graphic element, being illuminated by the mentioned light source, reproduces its specific information element in a specific and unique angular direction, as a result of which, when the laser-controlled part is fully focused in its focal plane or image plane, each information element occupies its own strictly a specific or separate observation zone or area.

 Hidden images can specify, for example, a hardware-readable pattern, in particular a barcode, with each graphic element corresponding to a specific section of the barcode.

In some cases, all sections separated from each other have the same simple geometric shape, which is not connected with or independent of the graphic composition of the main holographic image, for example, circles (dots), squares or rectangles. However, the area of these graphic elements should not exceed 3 mm ² .

 In other cases, graphic elements can be hidden from the observer by fully integrating them into the composition of the main holographic image. To do this, first select the smallest (by area), but nevertheless complete graphic element or object that forms part of the composition of the holographic image — preferably a graphic element of the composition, which is repeated as part of the kinetic or lenticular sequence of motion, and then divide this graphic element into two or more separate parts. Each of these graphic parts is holographically encoded with one piece of information that contains a laser-controlled part.

 Typically, characters, such as alphanumeric characters and the like, are used as graphic elements.

 Preferably, the structure generating the optically variable effects is formed as a single continuous structure. However, the elements can be defined by means of substructures separated from each other, the gaps between which do not cause light diffraction. In this case, the elements can be formed at separate stages.

 Typically, a device is part of a security hologram or protective optical microstructure (e.g., holograms, cinemagrams, pixelgrams, raster structure, stereograms, etc.). In this case, it is preferable that the part of the structure that additionally responds to coherent illumination is characterized by a lower lattice frequency than the part of the structure that forms only such an image or effect that can be observed in white light.

 Alternatively, it can be used as an independent protective optical microstructure, in which only a small area is available, for example, banknote fiber, where this part can provide both animation or apparent movement for public recognition, as well as a unique additional hidden protective device observed with a laser. It is especially useful to use this new detail as an additional means of public recognition, since latent images allow public recognition, and as a protective device for banknotes and, possibly, other important documents in which the optical microstructure is applied on a non-smooth or non-flat paper base, as disclosed here the means provide significantly higher resistance of the laser-controlled structure to paper roughness and creasing compared to previously known media you, since the structure is localized in a small area. It is also envisaged to use a device for protecting goods with a factory mark, financial plastic cards as a device for protecting against counterfeiting.

 As another possibility of using this device, one can consider a symbol such as a trademark controlled by a laser. For example, many protective holographic formations may contain the same, at first glance, a simple detail for public recognition, included in one area in the form of a set of points or graphic elements, providing a simple visual effect of the apparent movement (for example, a set of 2 lines of 3 points in each that move towards each other, turning), which could become a standardized part, but which, under coherent illumination with a laser, can reproduce completely different observables in the laser In light, messages detected only in coherent lighting. Thus, it is possible to improve all types of protective holograms and protective devices based on a diffraction grating, for example, raster devices and more specialized means, for example, cinegrams (OVD Kinegram Corp.) and exelgrams (State Organization for Scientific and Industrial Research (CSIRO), Australia), which can be used to protect any secret documents and in security labels, including those used in security labels or banknotes, for example, in the form of fibers in paper or holographic strips and labels, unifying the paper or other products and substrates.

 Of particular benefit can be the use in a window chain, commonly used in banknotes and other security documents, where, despite the presence of holographic fibers, the viewing area in each window greatly limits the degree of protection that a holographic image can have. The fact that it is possible to detect a visual image on such a small window area complicates both the manufacture of a visual protective device for easy effective public recognition and the attachment of additional optical protection with respect to hardware-readable or laser-readable images. According to the present invention, the chain may comprise a simple publicly controlled switching or moving pattern (potentially, however, sufficiently simplified to simulate by means of a bitmap pattern), which could also reproduce a protective hidden part controlled by a laser. Similarly, this part can be included in a repeating bitmap or graphic on a strip or sticker of a banknote to increase the degree of protection of the optical microstructures of the banknote, since the means disclosed here are much more resistant to wrinkling, paper roughness and other adverse operating conditions compared to previously disclosed parts.

 Another useful but slightly different use case for this kind of advanced hardware-controlled device is an advanced banknote security device based on the ideas of WO-A-92/094444. In a useful, more secure version of the security device for public recognition in the form of a security hologram used on a banknote, the use of repeating elements is provided, according to WO-A-92/094444, but, in contrast to the situation considered there, pairwise reproducing repeatedly repeating simple switching image using one or both of these holographic elements to provide an effect of apparent motion (e.g., translational or rotational) that are more difficult to fake in a holographic laboratory, and also providing a useful holographic animation detail for public recognition. In this sequence of repeating elements, which may appear to not overlap or slightly overlap to provide, for example, an effect that simulates 3D depth, or an effect that simulates a magnification during rotation, some or all of these elements may contain laser-controlled parts and observed at relatively simple conditions of coherent lighting created, for example, by a laser pointer.

 Another advantage of the preferred embodiments of the present invention is that they provide an additional, third level security check for a protective device that is different from previous systems. The first level of protection is an animated visible image created for visual observation, potentially, as part of the composition of a protective hologram. The second level of protection is the presence of a hidden message controlled by a laser, which can be detected even by a relatively unskilled observer using a simple source of coherent light, such as a laser pointer and viewing screen. An additional, third level of protection involves the analysis of reproduction angles and, possibly, bending planes of the image observed with a laser. This can be done for a more sophisticated verification of protection using either laboratory equipment, or reading equipment or a laser-based viewing device designed to identify the reproduction geometry of laser-controlled parts, giving more accurate results than those obtained with a laser pencil to provide additional characteristic verification of protection.

The following are some examples of protective devices in accordance with the present invention, with reference to the accompanying drawings, in which:
figure 1 is a diagram of the first embodiment of a device illuminated by white light;
FIG. 2 - various images that can be created using the device shown in figure 1;
FIG. 3 is a flow chart of a first embodiment of a device under laser lighting;
FIG. 4 is a structure formation diagram for use according to a first embodiment;
FIG. 5A and 5B are a flow diagram of a second embodiment of a device illuminated with white light and laser light, respectively;
6 and 7 are diagrams similar to FIG. 3, illustrating additional examples of devices under laser lighting.

 According to a first embodiment, the device is embedded in an embossed rainbow hologram for security purposes.

 The standard rainbow embossed hologram 1 (FIG. 1), which may additionally contain other holographic security parts (not shown), contains 6 additional points 2 included in one area of the composition, in this case provided sufficiently distinguishable. In this case, small dots are used (with a diameter of 0.25 mm to 1 mm), although a set of graphic elements or other characters can be used, for example, the letters that make up the word. When you turn 50 holograms in this case from left to right, when illuminated with white light or normal daylight 51, the holographic reproduction of the points is such that they appear to be very unusual in their movement relative to each other, and in this case 6 points are located in 2 lines of 3 points with the formation of 3 pairs of points that create the image. The direction of the holographic reproduction of the points is chosen so that it seems that the points simultaneously move in opposite directions when the hologram is horizontally rotated from left to right, as 3-5 positions corresponding to different rotation angles are schematically shown. This apparent movement provides an animated diffraction detail for public recognition, with images being formed close to the surface of the device.

 In FIG. 2 shows various other types of images that can be used instead of images of points in a plane, in accordance with FIG. In these examples, sets of letters are provided that appear sequentially as the device rotates. This sequence can be straightforward (Figs. 2A and 2B), form a circle (Fig. 2C) or expand, in other words, the letters appearing one after another are farther from the center point (Fig. 2D), or consist of repeating letters, like shown in FIG. 2E.

 In a preferred example where at least three reproduction directions are used, as shown in FIG. 1, and usually three or more pairs or sets of points or graphic elements, each element of the pair being reproduced in the same direction, a useful minimum requirement consists in forming an effective protective device for public recognition, as well as providing effective laser reproduction and some resistance to damage in any single area and some degree of simplicity alignment for laser playback.

 The second element of this new protective part can only be observed under laser lighting, and in this case there are hidden parts that can be observed with a laser, which an unskilled controller can easily check by simply illuminating the 6 (Fig. 3) part with a diode laser pointer, a laser pencil or another similar device and using the simplest viewing screen (7) that allows you to visualize off-plane playback of a hidden graphic image, although, of course, you can design a special The general reader, i.e. detector of authenticity. However, the advantage of this system is that it provides enhanced fidelity to the off-plane part (described below) and makes it very easy to verify the authenticity of the part observed in the laser light using a very simple, inexpensive means, such as a commercially available laser pointer and a simple viewing screen for Get an image of a hidden part. As the viewing screen 7, you can use just a sheet of paper. Each element of the device, being illuminated by coherent laser light, restores, outside the plane of the image observed in white light, the actual image of the corresponding hidden part with multiple magnification (for example, with an element diameter of 0.75 mm, the size of the actual image at a distance of 250 mm is about 25 mm , at a distance of 100 mm - about 15 mm). The small spatial extent of each element allows you to make the part invisible in the absence of illumination by a coherent beam.

 As can be seen from figure 3, six points 2 are organized in pairs, each of which is involved in the restoration of the corresponding latent image 7-9. Points 10, 11 form the first pair, restoring the image 7, points 12, 13 form the second pair, restoring the second latent image 8, and points 14, 15 form the third pair, restoring the third latent image 9.

 Since these latent images 7-9 are formed outside the plane of the normal image and at a distance from the device where they are focused, in normal white light they are normally invisible to the observer.

 For convenience, points 2 are positioned close enough to each other, which makes it possible to simultaneously illuminate them all with one laser beam, the diameter of which is usually 3 mm.

 Note that, unlike previous systems, since individual parts observed in laser light are localized in small areas of the base, the angle of the cone of light restored to form the image is small, which provides a very wide depth of field for the formation of an approximately focused image observed in laser light, and allows you to observe the image on the screen located relatively close (about 50-75 mm, if necessary) to the base, providing high brightness of the part, and at the same time a narrow viewing angle The ora and small area of the image plane make it possible to hide the image observed in laser light. This is in contrast to other known laser observing systems, where the latent image is distributed over a larger area, which prevents the image from being close to the medium and of sufficient brightness due to the latent image becoming easily visible in the light of the searchlight, and because that for the image in the near plane, a wide range of reproduction angles is required, significantly worsens any holographic image combined with it, while the method disclosed here provides for a complete lock tion of items observed in the laser light, and thus eliminates any deterioration of other aspects of the associated protective hologram.

 Note that, according to a preferred embodiment, each laser-controlled elementary part of a holographic structure generating optically variable effects is a hologram that creates 2 different images in 2 different focal planes, one (white image) in a focal plane close to or coinciding with the plane of the display hologram, where the elementary part is focused to demonstrate a visually recognizable graphic part to an observer viewing the goal the other, in the second focal plane, where you can normally visualize the projected "rainbow slit" in the embossed rainbow hologram. In this case, elementary holograms under coherent laser illumination restore a simple graphic detail, for example, a letter or shape, and this hidden laser-controlled off-plane detail is visible only under coherent (laser) illumination and is otherwise invisible to the ordinary observer in the so-called “white light” in such lighting conditions, such as a searchlight, artificial or natural lighting.

 It should be noted that the reproduction characteristics of each individual graphic element of latent images are almost indistinguishable from the reproduction characteristics of the colors of an element of a simple diffraction grating or a simple lenticular holographic detail (i.e., a part reproducing a very short iridescent holographic gap approaching with respect to visual perception observer, to the characteristic reproduction of a purely diffraction grating), which makes the characteristics of color reproduction and azhuschegosya laser controlled movement area is almost indistinguishable from a standard holographic moving parts. This allows you to effectively hide the presence of additional controlled messages read by the laser. This is very different from previously known commercial laser-controlled holographic parts.

 These other systems use various methods that are not as effective compared to the new system described here, which has several distinctive and important advantages over previous methods. Some previous methods involve applying a laser-controlled (or hardware-controlled) image over the entire hologram or a large portion of the hologram, which degrades the visible image due to the so-called “noise” of playback at a certain angle. These systems are also characterized by reduced image clarity observed in laser light when reproduced in coherent light, partly because the distributed image is much more prone to distortion due to paper roughness (for example, in the case of hot stamping foil) or surface irregularities (for example, in the case of labels), which cause blurring of the boundaries of the out-of-plane image due to small angular changes in the direction of restoration of the image due to the luminosity of the foundation.

 In addition, hardware-readable parts, being localized in the hologram composition area of the diffraction structure, are often very noticeable due to the relatively large amount of information stored in the laser-controlled part, which creates a large playback angle and a dimmer, like matte white, color of the reconstructed image by compared with more saturated colors of the diffraction pattern, which makes obvious the presence of additional detail. This often leads to a deterioration of the part in manufacturing due to the wide range of spatial frequencies in this area, due to which there are nonlinearities, reproduction problems and noise in the finished devices - to store such a relatively large amount of information, other systems usually need to combine a large number of different spatial frequencies which tend to compete, which leads to competition of interference fringes, saturation of the carrier and, thus, to a decrease in the efficiency of the controlled Azer parts and increased noise. These manufacturing issues do not pose a problem in the new system, since each element of the laser-controlled message is divided into separate small sections containing a limited number of spatial frequencies, much more similar to frequencies in holographic regions, which ensures ease of manufacture and minimization of deterioration during embossing during manufacturing .

 In contrast to these previous systems, the laser monitoring system disclosed herein has several distinct advantages.

 Firstly, each individual laser-controlled element of the disclosed system is localized in small areas (for example, points), which minimizes distortion of the reconstructed image due to insufficient flatness of the substrate or paper roughness, thereby providing a higher-quality laser-visualized image with less degradation and noise. due to surface irregularities, more easily controlled by coherent lighting.

 Secondly, each element controlled by a laser contains only a single simple graphic element (for example, a letter) as a laser-controlled part, acting as a component of the whole message. This makes it possible to simplify the microstructure as much as possible with respect to the width of the spatial frequency range, each individual part observed with a laser (i.e., to minimize the number of spatial frequencies in order to minimize the competition of interference fringes). This reduction in the required width of the spatial frequency range makes it possible to reproduce in white light a visual part that looks almost the same as a part of a diffraction grating, since it provides the reproduction of essentially saturated colors (rather than the reproduction of dim colors), and also allows for more efficient embossing of the part and make it less sensitive to noise arising during embossing due to saturation of the medium, which comes faster for lower brightness for more complex optical FIR microstructures.

 Thirdly, the localization of a simple graphic element in each laser-controlled spot, but with the subsequent use of various spots that reproduce different message symbols in different directions, again makes the part more resistant to the lack of flatness of the surface and microscopic surface roughness, since it allows to ensure good angular and spatial separation of parts observed with a laser to avoid overlap.

 Fourth, the preferential placement of laser-controlled spots or graphic elements allows you to use the distance between the graphic details so that at any given time the spot of a conventional laser pencil illuminates only one part that carries a particular symbol observed with the laser, thereby guaranteeing the greatest possible clarity of the detail observed with the laser for each character, by eliminating slightly different recovery angles possible in the case of illumination sharp elements corresponding to the same laser-readable symbol, while repeating laser-controlled elements in sets or pairs simplifies alignment and improves readability without precise alignment due to the fact that, for example, in non-limiting applications, it is illuminated at any given time for reading only one laser-controlled character of each type, which means that each part observed with a laser is repeated at least once, which makes the part intact more resistant, for example, to local wrinkling, deterioration or surface scratches, thereby improving the quality of laser control of old or wrinkled labels or documents, such as banknotes.

 The new system is better protected compared to previous systems by improving the masking of the hardware-readable part of the protective hologram, as well as the fact that an organization specializing in holographic and diffraction processes is more difficult to fake, and, moreover, acts as a diffractive protective part for public recognition. The following is an explanation of these benefits. The part is better camouflaged in a protective hologram, because, firstly, it reproduces a cleaner diffraction color than other previous parts observed with a laser, making it difficult to distinguish from other surface diffraction gratings and lenticular details of the hologram, which allows effectively mask the kit and the presence of laser-controlled parts. The part can also be additionally masked in a protective hologram, either in a composition or in the form of a spatially separated area, as a set of parts or graphic elements that provide a part of the apparent movement for public recognition, which is displayed to the observer when the hologram is rotated, for example, rotation, change in shape, image change or linear effect displacement. Thus, the new protective part acts as a device for public recognition due to the nature of the details of the apparent movement, which may be peculiar to the used methods of angular separation of the laser-controlled display in separate different directions assigned to separate spatially distinguishable areas.

 In FIG. 5 shows a second embodiment, which provides a protective device 20 as a single dot-like structure, the structure being made as part of a line of dots formed by parts of a surface diffraction grating, in the form of lenticular traveling strips. When rotating the device 21, illuminated by white light 22, the details of the surface diffraction grating, including the device 20, act together, providing a display of moving points. The device 20 itself consists of four sections 23-26, which form a pair of 23, 25 and 24, 26, which, when turning the device illuminated by white light, provides a pair of alternating images, indicated by positions 27, 28.

 In addition, each sector 23-26 is also arranged to reproduce a corresponding latent image 29, 30 under laser light. 5B, a pair of sectors 23, 25 forms a latent image 30, and a pair of sectors 24, 26 forms a latent image 29.

 In some cases, the device 20 can be used separately.

 The creation of elements of a hardware-readable part at the stage of manufacturing an optical microstructure is also difficult compared to previous devices, since it requires the creation of several separate focused graphic elements on or near the image plane of a visible hologram reproducing in several different diffraction directions, ideally to provide an effect of apparent motion or effects change of figures during rotation, as well as the creation of separately focused focus in these directions a laser-watched braze that can only be observed in coherent light. Traditional holographic processes are usually used to form this part, usually the conversion of H1 to H2, and then instead of using a short rainbow slit to design an elementary image, the rainbow slit is shaped into the desired graphic element observed with a laser. Then this process is repeated for each of several graphic elements, each drawing combines several movement details and at least two, preferably more, separate laser-controlled parts. In practice, 3 or more pairs or sets of individual graphic symbols or points are used in accordance with the level of complexity of creation and complexity of parts controlled by a laser, in which other techniques begin to produce worse results, and it is advisable to use such a number of separate parts to create a recognizable and rather complex part movements for visual public recognition as part of a hologram of a visual display or other diffractive security devices as necessary.

 This is a useful part to prevent counterfeiting, using commercially available so-called “raster” devices in which a substrate with a photoresist is exposed to two interfering laser beams to form a point diffraction grating, and then the pattern is moved stepwise between exposure positions to create an array of diffraction gratings recorded under computer control in stages and with repetitions (commercially available devices and in the literature from, for example, Dimensional Arts and Ahead Optoelectronics Inc.).

 The new security device disclosed here is a useful device for preventing counterfeiting, unlike similar raster systems, because the device disclosed here provides an outwardly simple visual holographic device for public recognition, in which the visual pattern displays a simple moving part for direct public recognition, while at the same time contains a significantly improved hidden laser-guarded protective part that a knowledgeable controller can use Visualize easily with a laser pointer and a simple screen to restore and monitor a laser-visualized message.

 In this case, although the visual detail of the movement can be faked using a bitmap pattern, off-plane laser-visualized parts to be observed in coherent light cannot be copied using a raster system that can reproduce a purely diffraction grating (in this case, the preferred form of the visual graphic element of the part observed with a laser can be either a dotted or continuous graphic symbol), since any attempt to copy as a visual detail, Also, a part observed with a laser using a raster system would be unacceptably complicated, since copying parts visualized by a laser requires breaking a separate graphic symbol into separate points, each of which is displayed in different directions, which would be extremely difficult if generally possible, given the spatial and angular resolution of almost all existing raster systems.

 Such reproduction is a big problem for other means of creating a protective image based on diffraction gratings, for example, based on the recombination of standard grating patterns, including “cinemagrams”, or based on electron beam recording methods, including “exgrams”, and provides much higher levels of control and complexity than holographic laboratories accessible to most traditionally equipped equipment, since this device is usually a component th protective holographic image containing many other items.

 According to a preferred approach, the device is formed in a holographic manner in a photoresist, creating a surface relief pattern suitable for electroforming a metal form of the interlayer for further manufacturing by embossing. For holographic formation, a variant of the known Benton-type H1-H2 process can be used to form a surface relief hologram in which this device can be combined with a 2- / 3-dimensional or 3-dimensional hologram or stereogram or any other diffraction grating or diffraction protective device known in the art. When restoring a laser-controlled part using coherent laser illumination, the graphic information that it contains is received and focused or displayed on the same plane as the Benton rainbow slits, which are restored in the same way when the visible main hologram is illuminated by the same source of coherent light.

 The surface embossed hologram is then copied using electroplating processes known in the art to form metal copies and, therefore, interlayers for holographic embossing, which can be used to emboss the device by the known replication method for holographic or diffraction embossing of optical microstructures. The devices are then included in the labels, the fake revealing labels, hot stamping foils and other similar materials used for mass replication of optical protective parts, which can then be attached to security documents, plastic cards and valuable items.

 One aspect of the use of this invention that provides its advantage is that the laser-controlled component of this invention, being recorded as part of a security hologram, diffraction grating, or similar system, always uses the spatial frequency of the carrier diffraction grating, which is lower than that of holographic interference structure. Reading a laser-controlled part using a laser pointer or a similar source offers the advantage that, since low-cost laser sources are almost always (today) laser devices operating at a red wavelength, red laser light diffracts from a laser-controlled part at a lower angle than on the visual holographic structure, which allows angular separation of the laser-controlled part from the visual protective hologram to facilitate observation to laser-controlled parts. Therefore, for simplicity of authentication, it is preferable to write the part observed with the laser into a coarse diffraction structure (i.e., into a carrier grating with a lower spatial frequency), and then the accompanying visual holographic part, so that usually the red laser light diffracts on it under smaller angle than on the visual hologram to provide angular separation. This technique of using a coarse diffraction grating for a hidden (for example, hardware-controlled) part provides that often the smallest dispersion element of a protective device helps to minimize image blur during restoration due to small changes in diffraction angles in different parts of the device due to the roughness of the substrate. Therefore, the use of this smaller diffraction angle for the laser-controlled part ensures that the diffracted reproduction from diffracted reproductions of the laser-controlled part is the least degraded due to the surface roughness of all components of the holographic or diffractive security device.

 According to FIG. 4, the method for enabling this additional hardware-readable part involves recording a second independent hologram H1 60 (Fig. 4A) corresponding to different regions of the original part for laser monitoring, say, 3 sections of the original recorded in 3 regions 60A, 60B, 60C of the hologram H1, instead of conventional methods for masking H1 with a rainbow slit, the H1 sections are masked in the form of the desired laser-controlled part. This H1 can then be used in the well-known sequence H1-H2 to convert the image controlled by the laser into the image plane of the hologram H2 61 (Fig. 4B). Then create, usually in a photoresist containing the plane of the visual image, a laser-controlled part of an H2 hologram animated according to the diffraction directions, which are determined by the initial composition H1 as a laser-controlled part. The use of a reference beam angle smaller than any associated visual security hologram or diffraction protective device ensures that the laser-controlled part is recorded onto the diffraction grating with a greater pitch than the visual diffraction protective device. Subsequently, this image can be combined with a visual security hologram by recording the second hologram H2 on a photoresist from a separate H1 corresponding to the necessary visual security image. Then, the photoresist plate is developed in the usual manner to form a surface embossed hologram. Other methods can be used, for example, the creation of a single complex composite H1 containing all the elements of both the visual hologram and the areas of laser control recorded in separate sections, and the hologram H2 is recorded in one conversion step.

 Other alternative and equally suitable methods for forming a laser-controlled part and 2- / 3-dimensional protective holograms may include the use of masks to specify the graphic details of the visual image on the hologram in the image plane and the use of blurry or lenticular scattering sheets masked by appropriate shapes to form an object beam with the addition of a separate reference beam, according to the prior art.

 Another image-production technique involves creating a single, multiplicable hologram of a laser-controlled part, copying it onto a metal original by electroforming, and then using mechanical recombination methods (i.e., selectively embossing areas using a flat printing machine) to include this part in a protective hologram or purely diffraction a device, such as a moviegram or exgram, to increase the degree of protection of these devices.

 We also note that, although this technique is usually used to create a surface embossed embossed optical microstructure, a laser-controlled part, such as that disclosed here, can be used in a volume holographic security device using recording materials such as silver halide emulsions, dichromated gelatin, and holographic photopolymers ( e.g., manufactured by EI Dupont, Holographics Division and Polaroid Corporation, Holographics Division) using reflective holography known in the art (e.g. G. Saxby, "Practical Holography", Prentice Hall).

 In this case, the methods of formation and manufacture will differ in detail. However, the principle of creating an improved hidden detail, observed in coherent laser light, for multiple small graphic symbols, which are also used to obtain the effect of the apparent movement for public recognition, remains applicable, i.e. the use of several holographic elements having both a graphic image in the plane of the visual image intended for visual authentication, in the form of a figure or graphic element, and a graphic figure in an off-plane part, forming a laser-controlled hidden part, observed only in the light of the laser.

 In the examples described above, the protective device when illuminated with white light reproduces several small points. In FIG. 6 shows an example of how the structure 70 reproduces graphic characters, in this case the letters NAME, when illuminated with white light, usually sequentially as the device rotates, while under laser lighting 6, the CODE characters indicated at 71 are restored, and in another plane.

 Fig. 7 shows a modified example corresponding to Fig. 6, in which, under laser illumination, the barcode 72 is restored as a latent image under laser illumination. Each section of the structure that forms the letters NAME when illuminated with white light corresponds to the corresponding section of the barcode 72.

Claims (20)

1. A protective device for protecting documents and other valuable products from illegal reproduction or counterfeiting, containing a holographic structure that generates optically variable effects, containing at least two separate sections, each of which is configured to create, under white light, optically variable image, consisting of at least one specific graphic element located in or near the image plane, coinciding or adjacent to the plane of the device VA, and which is made with the possibility of coherent lighting to create at least one separate latent image, which is associated with the product or document for which a protective device is provided, in the form of a sign, the image plane of which is located at a distance from the physical plane of the device, latent images are restored at different angles to the normal of the base supporting the device, so that the latent images are spatially separated on their image plane, and the hidden images Reflections are almost invisible when illuminated with white light. 2. The device according to claim 1, characterized in that the structure generating the optically variable effects is configured to create, when illuminated with white light, an optically variable image that moves when the device is rotated. 3. The device according to claim 1 or 2, characterized in that the structure generating optically variable effects is made in the form of a single continuous structure. 4. The device according to claim 3, characterized in that each element of the holographic structure that generates optically variable effects has a maximum transverse dimension of less than 3 mm and, preferably, less than 1.5 mm. 5. The device according to claim 3 or 4, characterized in that it contains several pairs or sets of at least three similar sections, each element of the pair or set is intended to form, under coherent illumination, the same latent image as other item (s) of a pair or set. 6. A device according to any one of claims 3 to 5, characterized in that a single holographic structure generating optically variable effects is included in a set of additional structures generating optically variable effects, the single and additional structures generating optically variable effects being illuminated by white light, when you rotate the basics of the joint action to create the effect of a moving image. 7. The device according to claim 1 or 2, characterized in that the sections of the structure generating optically variable effects are made in the form of areas separated from each other. 8. The device according to claim 7, characterized in that it contains several pairs or sets of regions, and each element of the pair or set has almost the same design. 9. The device according to claim 7 or 8, characterized in that each region has a maximum transverse dimension of less than 3 mm and, preferably, less than 1.5 mm. 10. The device according to any one of the preceding paragraphs, characterized in that the structure generating optically variable effects is made in the form of a diffraction grating or a holographic structure, for example, a protective hologram. 11. The device according to claim 10, characterized in that the part of the structure that additionally responds to coherent lighting is characterized by a lower lattice frequency than the part of the structure that responds to white light. 12. The device according to any one of the preceding paragraphs, characterized in that the structure that generates optically variable effects is a surface relief structure. 13. The device according to any one of the preceding paragraphs, characterized in that the latent images contain graphic elements, alphanumeric characters, characters or hardware-readable patterns, such as barcodes. 14. The device according to item 13, wherein each section is configured to form a latent image that is part of a hardware-readable pattern. 15. The device according to any one of the preceding paragraphs, characterized in that the sections have almost the same shape. 16. The device according to any one of the preceding paragraphs, characterized in that the sections have a simple geometric shape, such as a circle, square or rectangle. 17. The device according to any one of claims 1 to 15, characterized in that the sections are in the form of graphic characters. 18. The device according to 17, characterized in that the sections specify alphanumeric characters. 19. The device according to any one of the preceding paragraphs, characterized in that it is formed by holographic means by converting H1 to H2 of the Benton type. 20. Document or valuable product, characterized in that it is equipped with a protective device according to any one of the preceding paragraphs.

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