Patent Application
20090034389
The invention concerns a multi-layer body having an optically machine-readable identification, a method of manufacturing such a multi-layer body and a method of reading an item of information out of such a multi-layer body.
EP 0 718 795 A1 discloses an information strip with optically encoded information. Optical markings are arranged on the information strip in bit lines, wherein at least two bit lines with identical division into surface portions of equal size are required. Each surface portion is occupied for example by an optical diffraction element. The diffraction elements of the one bit line involve the same grating parameters (spatial frequency, profile shape, azimuth and so forth) and differ from the diffraction elements of the adjacent other bit line. A respective surface portion from the one bit line forms with the adjacent surface portion from the other bit line a bit pair representing a single bit of the information. In the case of that information strip, after manufacture it is possible to write an item of information once, wherein the optical characteristic of the surface portion is irreversibly altered in the operation of writing in one of the two surface portions of the bit pair.
It is known from EP 0 883 085 A1 that each surface portion of a single-line information strip has a plurality of partial surfaces which are occupied alternately with one of two different optical diffraction elements from an amount of n diffraction elements. The diffraction elements of a sub-amount involve the same grating parameters (spatial frequency, profile shape, azimuth etc) and differ from the diffraction elements of the other sub-amounts. Each surface portion differs from its two neighbors by the selection of the diffraction elements for the partial surfaces. The information of those information strips is established by manufacture and cannot be altered individually for each information strip.
WO 00/62237 A2 discloses an information strip with raster elements which are arranged in two lines and which are of equal size, wherein the one diffraction structure of the one line differs from the other diffraction structure of the other line and the grating grooves of the fine relief structures of the diffraction structures are oriented substantially parallel to the lines. A respective raster element from the one line represents a single bit of the information, with the adjacent raster element from the other line. With that information strip, after manufacture, an item of information can be written once, in which case the optical characteristic of the raster element is irreversibly altered in the operation of writing in one of the two raster elements of a bit.
A reading device must simultaneously read out the diffraction structures in both lines of the information strip, in which respect the reading field is to be oriented as exactly as possible with respect to the separation line between the two diffraction structures. The tolerance which can be accepted is not more than ±0.5 mm. Inlays in plastic cards or the like however have a typical tolerance of ±1 mm in relation to the edges.
Now the object of the invention is to provide a machine-readable individualisable security element which is insensitive in relation to tolerances and which affords a high security standard, and methods of manufacturing the security element and reading out the information stored in the security element.
The object of the invention is attained by a multi-layer body comprising an optically machine-readable identification, wherein the multi-layer body has at least one first plastic material layer with a microscopically fine relief structure shaped in that layer and the optical effect of the microscopically fine relief structure can be altered region-wise for writing in an item of information, wherein it is provided that the multi-layer body has a plurality of first and second regions, wherein in the first regions a microscopically fine first relief structure and in the second regions a microscopically fine second relief structure which is different from the first relief structure and which has a different optically machine-detectable effect are shaped in the first plastic layer, the first and second regions are arranged in the region of the optically machine-readable identification in the form of a background pattern encoding a first item of information, and in the region of the optically machine-readable identification the optical effect of the microscopically fine relief structures is altered in third regions which at least partially cover over first and/or second regions for writing in an individualised code pattern which encodes an individualised second item of information and which overlaps the background pattern.
The object is further attained by a method of manufacturing a multi-layer body comprising an optically machine-readable identification, wherein the multi-layer body has at least one first plastic material layer with microscopically fine relief structures shaped in said layer and the optical effect of the microscopically fine relief structures can be altered region-wise for writing in an item of information, wherein it is provided that an optically machine-readable identification in the form of a background pattern encoding a first item of information is introduced into the multi-layer body, wherein a plurality of first regions with a microscopically fine first relief structure and a plurality of second regions with a microscopically fine second relief structure which is different therefrom and which has a different optically machine-detectable effect is shaped into the multi-layer body, wherein the first and second relief structures are provided with an optically effective reflection layer or an optical separation layer; and in the region of the optically machine-readable identification the optical effect of the microscopically fine relief structures is altered in third regions at least partially covering over first and/or second regions for writing in a code pattern which encodes an individualised second item of information and which overlaps the background pattern.
The object is further attained by a method of reading out a first and a second item of information from a multi-layer body comprising an optically machine-readable identification which has a plurality of first and second regions, wherein the second regions have a different machine-detectable optical effect from the first regions and the first and second regions are arranged in the region of the optically machine-readable identification in the form of a background pattern encoding a first item of information selected from a pattern amount, wherein the elements of the pattern amount have the same code structure and wherein in the region of the optically machine-readable identification third regions at least partially covering over first and/or second regions form an individualised code pattern which encodes an individualised second item of information and which overlaps the background pattern and whose optical effect is different from the optical effect of the first and second regions, wherein it is provided that with an optoelectronic reading device a first electronic image of the first relief structure is produced, from which a first signal pattern is generated, and a second electronic image is produced of the second relief structure, from which a second signal pattern is generated; the first and second signal patterns are integrated portion-wise in accordance with the code structure of the pattern amount; the first item of information is determined from the integrated signal patterns; and the individualised second item of information is determined by addition in respect of amount of the first and second signal patterns.
The multi-layer body according to the invention is distinguished by its insensitivity in relation to positional intolerances upon being applied to a carrier substrate such as for example an identity card and a high level of safeguard against counterfeiting and/or manipulation of the stored information. The multi-layer body has an optically readable background pattern encoding the first information which for example can form a security feature and/or a feature in respect of origin and/or a classification feature. The individualised second item of information is arranged on the background pattern, the second information being represented by regions in which the background pattern is altered. That makes counterfeiting of the individualised code pattern very difficult because the background pattern also has to be counterfeited at the same time and in addition the arrangement of the individualised code pattern on the background pattern has to be counterfeited.
The background pattern can be introduced in manufacture of the multi-layer body. It is of such a nature that it does not give rise to any additional manufacturing complication and expenditure and in addition does not require any additional items of equipment. The microscopically fine relief structures can be introduced into the multi-layer body in accurate register relationship by known methods such as hot embossing or by shaping in UV-hardenable lacquer. These are inexpensive manufacturing methods if large numbers of items are produced, which is possible due to separation at the manufacturing side of production of the background pattern and production of the individualised code pattern. That therefore affords a potentially high level of security and a code which can be very inexpensively individualised. That is in contrast to known high-security systems which typically are highly expensive and difficult for mass production. The multi-layer body can also be a film body in which further security features and/or decorative elements are shaped, which in that way are in register relationship with the above-mentioned relief structures.
The optical effect of the microscopically fine relief structure can be altered by an alteration to the relief structure itself (for example by laser ablation) or by an alteration to the layers optically co-operating with the relief structure, as described more fully hereinafter, or the layer having the relief structure (for example by a thermochromic dye in the embossing layer) or the subjacent layers are altered (for example adapted to the refractive index), that is to say covering the surface with a transparent plastic material prior to application of a metallic or dielectric layer so that the grating is so-to-speak extinguished.
The proposed method of reading out the items of information stored in the multi-layer body according to the invention easily permits parallel output of the first and second items of information, insofar as it is proposed that the first item of information is mathematically reconstructed from the second item of information and for that purpose additional items of information are obtained from the mathematical amount of the items of background information provided. It can therefore be provided for example that the mathematical amount of the items of background information does not include all mathematically possible combinations. Such an item of additional information represents a further security level which cannot be overcome by merely imitating the multi-layer body manufacturing principle.
Further advantageous configurations are set forth in the appendant claims.
It can be provided that the relief structures in the first and second regions are formed with an optically effective reflection layer or an optical separation layer. The optically effective reflection layer can be a reflecting layer or a reflecting layer system which can be made from metal, semiconductor or dielectric. It is also possible to provide liquid crystal layers, in particular cholesteric liquid crystal layers. It is also possible to provide pigmented lacquer layers or lacquer layers having organic dyes. The reflection may also involve total reflection which is to be observed at the interface between two layers involving different optical refractive indices, or the layering systems are only visible through (polarisation) filters.
It can further be provided that the optically effective reflection layer or the optical separation layer is covered by a protective layer which has a thermochromic dye. The thermochromic dye can permanently alter its color due to a thermal effect, wherein the color change can involve a change in the transparency of the protective layer.
It can advantageously be provided that in a region which represents a bit of the individualised code pattern of the value ‘1’ the reflection layer or the optical separation layer is removed or optically altered or is covered by an opaque layer or the relief structure is altered. It can also be provided that the layer is altered under the relief structure, for example by application of a layer adapted in refractive index prior to application of the metallic or dielectric layer or by an alteration to the adhesive layer.
Alternatively it can be provided that in a region which represents a bit of the individualised code pattern of the value ‘0’ the reflection layer or the optical separation layer is removed or altered or is covered by an opaque layer or the relief structure is altered. In that way the multi-layer body can be particularly well adapted to the conditions of use or the purpose of use. In the case of codes which have a plurality of successive identical bits, the background pattern can also be recognised by a naked eye. Because the background pattern can now be recognisable either in ‘0’ regions or in ‘1’ regions the individualised code pattern can always be such that the background pattern can be readily recognised.
Introduction of the individualised code pattern can be provided at various locations. Serial numbers can be applied for example at the manufacturer or at a central location, for example at a central passport issuing location. The individualised code pattern can however also be applied at decentral issuing locations, for example embassies. The individualised code pattern can also be a composite code pattern which for example includes a production number which is applied in manufacture, a country code or a year code which is applied at the central passport issuing location and a passport number which is applied at the decentral issuing location. In that respect the impression can be given that the individualised code pattern was applied in one working step.
It can further be provided that associated with a first and/or second region of the background pattern encoding a first item of information there is a plurality of third regions of the individualised code pattern encoding an individualised second item of information. That measure also contributes to the background pattern being recognisable and evaluatable even after application of the individualised code pattern. It is also possible for the data to be represented by more than two conditions. The degree of reflection or the degree of transmission of a layer can for example represent five values (0%, 25%, 50%, 75% and 100%) and/or the polarisation of diffracted light can involve one of four different directions (0°, 33°, 66.6° and 90°) and/or the relative strengths of the various spectral regions of the diffracted light, measured for example with a color-sensitive CCD sensor, can represent an item of information. That permits a higher level of information density for, instead of the two binary values 0 and 1, it is thus possible for example to represent hexadecimal values.
Further advantageous configurations are directed to the nature of the individualised code pattern.
It can be provided that the individualised code pattern is a one-dimensional bar code. Bar codes are wide-spread in particular for identifying articles. They produce the impression on the part of the viewing person that the code is stored in a sequence of bars of differing widths.
It can further be provided that the individualised code pattern is a two-dimensional bar code. The two-dimensional bar code is also a frequently used code.
Because the individualised code patterns are known code patterns, the background code is firstly perceived as an optical creative design means and is thus withdrawn from broad public awareness and perception.
Further advantageous embodiments are directed to the configuration of the relief structures.
It can be provided that the first and second relief structures are asymmetrical relief structures. The asymmetrical relief structures involve periodic structures having two flanks of differing steepness or gradient. Incident light is therefore preferably deflected in one direction. If the period length of the relief structure is of the order of magnitude of the wavelength or the mean wavelength, the light is diffracted at the relief structure. This can involve for example a blaze grating which is characterised by the grating line spacing and the blaze angle at which the grating elements are inclined. Blaze gratings deflect as much light as possible into a given diffraction order and therefore generate particularly bright diffraction images.
It can be provided that the first and second relief structures have a different k-vector.
It can advantageously be provided that the direction of the k-vector of the first relief structure differs from the direction of the k-vector of the second relief structure by 180°. In that respect it can be provided that the magnitude of the k-vector is identical, that is to say this involves two identical relief structures which are rotated through 180° relative to each other.
It can also be provided that the first and second relief structures have a different grating period.
It can further be provided that the first and second relief structures have a different grating form. Advantageously this can involve relief structures which are combined with an anisotropic matt structure. By way of example the first relief structure can be the matt structure which is combined with a polarisation grating for 0° and the second relief structure can be the matt structure which is combined with a polarisation grating for 90°.
It can also be provided that the first and second relief structures have a different grating depth.
With the above-described configurations, the first and second relief structures can be so designed that they produce markedly distinguishable optical effects, in particular in relation to inclinedly incident light. This can involve both changes in the brightness or intensity of the light deflected by the relief structure, and also color effects if the relief structure is illuminated with polychromatic light, for example with daylight.
It can further be provided that the first and second relief structures have a different polarisation effect caused by scatter and/or reflection. Polarised light can be influenced and/or identified by means of arrangements of one or more polarisation filters. It can therefore be provided that light polarised by the one relief structure passes unimpededly through the arrangement and light polarised by the other relief structure is attenuated. It can also be provided that the relief structures are illuminated with polarised light and in that case for example rotate the polarisation plane. The above-described arrangement comprising one or more polarisation filters can be provided for evaluation purposes.
A further advantageous configuration provides that the first and second relief structures are in the form of a hologram or a KINEGRAM®. That embodiment can be preferred in order to embed the individualised code pattern in a jewellery element or to make the background pattern particularly forgery-resistant. It can further be advantageous for each portion of the hologram or KINEGRAM® to reproduce almost all the information.
It can also be provided that the first and second regions form a graphic pattern or are part of a graphic pattern.
Further configurations are directed to the method of writing the individualised code pattern in the multi-layer body.
It can be provided that the individualised code pattern is formed by a thermal effect, wherein the reflection layer or the optical separation layer is removed or is altered in respect of its optical effect or the relief structure is altered or a thermochromic dye of the protective layer is activated.
It can also be provided that what is referred to as a PCI (polycarbonate insert) is provided with an individualised code pattern. In particular the KINEGRAM® far the PCI variant can be of a very filigree nature, at least in the regions which are individualised, for example with a photograph or with data such as name and expiry date. In those regions—only between 10% and 50% of the KINEGRAM® are optically active (that is to say they have a grating)—and in those active regions and only in those active regions there is a metallic layer for the diffractive structures. Consequently the KINEGRAM® is completely translucent (that is to say the KINEGRAM® is completely invisible) in between 50% and 90% of the card area, and in that region a laser can easily personalise the photograph and the data. It can consequently be provided that personalisation takes place under the KINEGRAM® and its film system (including the adhesive layer). It is possible to provide the following structure:
In other embodiments it can be provided that the individualised code pattern is formed by printing on an opaque layer.
It can also be provided that the individualised code pattern is formed by the reflection layer being removed by thermal action or altered in its optical effect or the relief structure being altered or a thermochromic dye of the protective layer activated or the transparent protective layer being converted into an opaque protective layer, in the regions of the optically machine-readable identification, that are not associated with the individualised code pattern. The transparent protective layer can be for example a laser-sensitive polycarbonate protective layer which is arranged over a diffractive layer which is metallised or provided with HRI. To carry out that method step, it is possible to use lasers, wherein permanent alterations in a layer which is covered by one or more layers can be effected by virtue of the choice of the kind of laser and the setting of the laser parameters. The individualised code pattern is therefore well protected from damage and from falsification.
It can be provided that an opaque layer is printed on regions of the optically machine-readable identification, that are not associated with the individualised code pattern. Such printing can be provided for example for edge regions of the multi-layer body. It is also possible to apply by printing markings to which a reading device can be aligned.
It can further be provided that the individualised code pattern provides an item of information formed from an individualised item of information and a check code calculated from the individualised item of information. The check code can serve on the one hand to recognise reading errors and optionally correct same. It can however also be provided to detect subsequent changes to the individualised code pattern.
It can further be provided that the individualised code pattern is provided with a start and/or stop portion. The start and/or stop portion can be of the same configuration for all individualised code patterns in order for example to provide correction data for a reading device. It can also be provided that a delimitation sequence for synchronisation purposes is introduced into the code pattern.
A further advantageous configuration provides that the first item of information is used for characterisation of a security document.
It can be provided that the first item of information includes the nature and/or the purpose of use and/or the origin of the security document.
Further configurations are directed to the method of reading out the items of information.
It can be provided that the multi-layer body is illuminated by a light source and the first and second signal patterns are determined with two sensor lines or sensor arrays arranged on both sides of the multi-layer body. This can involve for example a light source which is arranged centrally over the multi-layer body and the beams of which are so deflected by the relief structures of the multi-layer body that it is deflected in a direction on to the sensor lines or sensor arrays arranged on both sides of the multi-layer body. It can preferably be provided that more than one sensor pixel is associated with each portion of the multi-layer body which embodies one bit. In that way for example a reliable sensor signal can be produced by averaging. It is possible for example to provide 8 sensor pixels per bit.
Alternatively it can be provided that the multi-layer body is illuminated by two light sources arranged on both sides of the multi-layer body and the first and second signal patterns are determined with a sensor line or a sensor array arranged above the multi-layer body, wherein the two light sources are alternately set in operation. In an advantageous configuration it can be provided that the one light source emits red light and the other light source emits blue light, wherein the first signal pattern diffracts for example into the −1st order and the second signal pattern into the +1st order and both light sources simultaneously illuminate the two signal patterns. A single measurement gives both the +1-information and also the −1-information. The −1-information is contained in the red channel of the image while the +1-information is contained in the blue channel. Consequently an image (for example JPEG) contains the −1-information and the +1-information simultaneously. It is also possible to measure two polarisation states with one image (red can contain the S-polarisation information while blue can contain the P-polarisation information).
The invention is described by way of example hereinafter by means of a number of embodiments with reference to the accompanying drawings in which:
a shows an information track of a security element in strip form in accordance with the state of the art,
b shows diagrams illustrating the output signals produced by a reading device on the basis of the information track in
a shows an unwritten information track of a first embodiment of a security element according to the invention,
b shows diagrams illustrating the output signals produced by the reading device in
a shows an individualised information track in
b shows diagrams illustrating the output signals produced by the reading device in
a shows an unwritten information track of a second embodiment of a security element according to the invention,
b shows an individualised information track in
a shows an unwritten two-dimensional information track of a third embodiment of a security element according to the invention,
b shows an individualised information track in
a shows a reading device for reading out the information track in
b shows a plan view of the information track in
a shows the reading device in
b shows a plan view of the information track in
a shows a photographic image of a security element according to the invention as a front view,
b shows a photographic image of a security element according to the invention as a rear view, and
a and b show embodiments of holographic background patterns.
a shows an information track 10t of a security element according to the state of the art. As can be seen from
For writing an item of information into the information track 10t either the relief structure A or the relief structure B of the bit portions 1t through 6t is removed, for example by laser ablation, or is covered with a layer which is non-reflective or poorly reflective, for example by applying a color layer by printing. In the case where the security element is in the form of an inlay the information can also be written by blackening selected regions of a transparent cover layer, for example with a laser. Therefore, to write a ‘0’ into a bit portion the relief structure B of the bit portion is removed or covered over. The operation of writing in the information is typically effected after application of the OVD to a substrate. More specifically laser ablation can
A reading device 20 as shown in
The beams 23 are deflected by diffraction at the regions A, B of the information track 10t in such a way that they are incident on the detector array adjacent to the region. In the example shown in
b shows diagrams illustrating the output signals 21a and 22a of the detector arrays 21 and 22 for an ideal reading operation, that is to say for a tolerance-free position of the information track 10t relative to the two detector arrays. The abscissa of the diagram denotes the association of the output signal with the bit portion and the ordinate denotes the signal level of the bit portion. This diagrammatic view does not take account of the fact that n individual sensors can be provided per bit portion on the detector array, of which each in itself can form an individual output signal which varies about the ideal value within a tolerance range.
a and 4a now show a first embodiment of a security element according to the invention with an information track 10. The information track 10 is provided during manufacture with a binary code which involves bit portions 1 through 7 in strip form, the surface of which can have either a relief structure of type A or a relief structure of type B, as described hereinbefore. In the
b, similarly to
The information track 10 can be individualised prior to delivery of the security document.
As can be seen from
The asymmetry of the blaze gratings which form the information track 10i, produced by hot embossing, involves a ratio of 5:1 through 20:1. With those values the individualised information code can be very easily separated from the background code. For high values of asymmetry, which for example can be implemented with asymmetrical achromatic gratings or highly polarised codes, it is more difficult to separate the individualised information code from the background code. In that case it can advantageously be provided that the sum and the difference of the two codes (−1-code and +1-code) are determined and the individualised item of information is calculated from those two measurements.
The width of the information strip 10i is determined by the measurement field of the detector arrays 21, 22 and the maximum positional tolerance for which the information strip is designed. The width of the information strip should be of the order of magnitude of the width of the measurement field or smaller and/or it should be greater than the maximum positional tolerance. The positional tolerance which, upon application of security elements to security documents in the form of plastic cards, is generally ±1 mm, leads to no adverse effect when reading the information out of the information strip 10i. As already described hereinbefore, that is to be attributed to the fact that the measurement zone of the detector array can be anywhere within the information strip. In the case of an information strip according to the state of the art the measurement field must be disposed along or close to the center line of the two regions with the relief structures A and B.
a and 5b now show a second embodiment of a security element according to the invention.
a shows an information track 510 which is introduced into the security element in manufacture. The information track 510 can be integrated into a security element of higher order, for example a KINEGRAM® so that it is visually not striking. The information track 510 is provided during manufacture with a binary code which is bit portions 1 through 8 in strip form, the surface of which can have either a relief structure of type A or a relief structure of type B, as described hereinbefore. The bit portions represent the binary code ‘01101010’ in accordance with the association described hereinbefore. The information track 510 has edge portions of a length T, in the longitudinal direction in which it extends. The length of the inner portion of the information track 510, which is provided for representation of the binary code, is denoted by L. A bit portion 1 through 8 in strip form is therefore of a length L/8. The two edge portions are sub-portions of the outer bit portions 1 and 8 which are therefore of a length (L/8+T).
b now shows an individualised information track 510i formed from the information track 510 in
As can be seen from
The bar code 511 is provided with a leader and a trailer so that the data portion on the bar code can be easily identified. The leader and/or the trailer also simplify error correction if it is provided that the leader and the trailer are identical for each individual bar code. It is however also possible to dispense with the leader and the trailer without casting doubt on the function of the information track or the readability of the bar code 511. In regard to the high error tolerance of the information track 510i attention is directed to the description relating to
The information track 510i shown in
In the embodiment shown in
The information track used as the background track is encoded with 8 bits, that is to say each bit is of a width of 2.25 mm and 27 data bits are allotted to each background bit. It is important for the intended purpose that a plurality of data bits are allotted to a background bit in order to be able to reliably read out the information track 510. In particular portions of the information track 510i, in which a plurality of ‘0’ bits follow each other are suitable for the reading-out procedure.
It can however also be provided that the ‘0’ bit is produced by removal of the reflection layer and the ‘1’ bit has either the relief structure A or the relief structure B. In that case, in particular portions of the information track 510i, in which a plurality of ‘1’ bits follow each other, are suitable for reading out the information track 510.
a and 6b now show a third embodiment of a security element according to the invention with a two-dimensional information field 610, from which an individualised information field 611i can be produced by applying a two-dimensional bar code 611.
The information field 610 shown in
b now shows the individualised information field 610i, to which the two-dimensional bar code 611 is applied. The bar code 611 in the
a through 8b now show an operative principle suitable for reading the information out of the information field 610i in
a shows a reading device 70 formed from an electronic camera 70k and two light sources 71l and 71r in strip form. The electronic camera 70k has a 2D sensor which for example can be a matrix-form sensor. It is alternatively also possible to provide a sensor in line form or point form which is connected to a suitable deflection system or which is movable in such a way that it can scan any point of a two-dimensional area. The electronic camera 70k is arranged over the individualised information field 610i.
The light sources 71l, 71r are connected to a change-over switch (not shown) so that either the light source 71r or the light source 71l can be switched on. In
a shows the arrangement of
All the information stored in the bar code 611 can be ascertained from the overlap of both partial images of the information field 610i, wherein the distribution of the relief structures A and B in the information field 610i can serve for authentication of that information. A further advantage of the arrangement described in this embodiment is the high level of insensitivity to tolerances and soiling and/or damage. Troubles can be very easily eliminated in particular if the configuration of the information field 610 used as the background for the bar code 611 is known (see
The arrangement is further insensitive in relation to ageing or positional tolerances of the light sources 71l and 71r because the two partial images produced by the camera 70k can be electronically standardised to equal brightness, with the incorporation of the information field 610.
a and 9b now show photographs
The relief structures A and B used in the above-mentioned examples of use can differ from each other in respect of their polarisation properties and/or their grating period and/or their grating direction and/or their grating form and/or their grating depth and in that way are detectable for optical reading devices. The relief structures can also be computer-generated holograms. That large number of possible variations additionally causes difficulty in making unauthorised copies or can limit verification to reading devices which are especially designed and/or which are not available to the general public, in which case the operation of reading out the information of the bar code with commercially available reading devices can be possible. The relief structures can also be projected on to a screen and a CCD camera can acquire the screen representation. It is therefore possible to be highly flexible in terms of the design of the reading device.
a and 10b now show information fields 1010 and 1011 which can be used as the background and which have computer-generated holograms 1012a and 1012b which optically differ from each other. Because of the property of the holograms that each partial region of the hologram can reproduce the information of the hologram, holograms can contribute to further increasing the tolerance insensitivity. The holograms further contribute to enhancing the level of safeguard against forgery for a hologram can only be imitated at a very high level of complication and expenditure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2006 006 323.6 | Feb 2006 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2007/001098 | 2/9/2007 | WO | 00 | 9/25/2008 |
