EP1995075A1 - Data medium comprising printed identification information and forgery-protection means - Google Patents

Abstract

The support e.g. card (10), has invisible anti-forgery units subjected to change in appearance in event of attempt to do personalization. The units are formed by subdividing a pixel into a matrix of specific number of dots, where each dot has a different color density to obtain an average color density of the matrix that is equivalent to the predetermined color density for the corresponding pixel. Certain dots of the matrix are pre-sensitized to induce more or less rapid darkens of the color of the dots in the event of personalization, with respect to the other non pre- sensitized dots. An independent claim is also included for a method for securing a data or information support.

Description

The present invention relates to the security of information carriers or data. More particularly, the invention relates to the securing of information media so that the identification information printed on their surface in particular is not altered or modified, and that the media are not thus reused fraudulently.

The invention lies in the field of identification documents chip or without chip, such as driving licenses, identity cards, membership cards, access badges, passports, bank cards, electronic purses, multi-application cards and other valuable papers. Because of the value and importance associated with each of these documents, they are often subject to unauthorized copies, alterations, modifications, and counterfeits.

For example, laser printing does not prevent the addition of information. Such an addition of information may, for example, lead to completely changing a photograph by adding more hair and / or a mustache and / or glasses etc. An example of falsification of photography by adding blackened areas by means of a laser beam is shown on the figure 1 . On the original map 10, information concerning the identity of the holder is written in a text box 11, and a photograph 12 of the holder is printed for example by means of a laser beam, by burning the surface of the card body. . Local discoloration of the resulting surface depends on the available energy, the inscription time as well as the material of the card body used. Since this photograph is printed by laser burning the surface of the card body, it is indelible and the blackened areas can not be removed. However, it is possible to add blackened areas for example in the text area 11 to change the identity of the holder by adding alphanumeric characters, but also on the photograph 12 to change the face of the holder. In the example of the figure 1 , the original photograph 12 of the map 10 is modified, hair is added by means of a laser beam and shaded areas are added to accentuate the cheekbones and the complexion of the skin, so that a new falsified photograph 12A is performed on the map 10A. Likewise, the identity of the cardholder is falsified by modification and addition of alphanumeric characters 11A.

To prevent such frauds being made on the identification documents, different types of security means are used. One solution is to superimpose curved clear lines, also called guilloches, on an identification image, such as photography. Thus, if a subsequent print is made, the guilloche blacken and appear darker than the added overload.

The patent application FR2890332 describes a solution which consists in arranging invisible anti-forgery means around the graphic personalization, that is to say in the unprinted areas of the surface of the support and in the immediate vicinity of the printed areas, i.e. say alphanumeric zones or image zones. These anti-falsification means comprise for example a pattern of lines that are revealed at the time of additional personalization. So, if a fraudster wants to add hair around the photo, the darker lines will appear in the hair added. Similarly, if the identity of the holder is changed, by adding a second surname for example, as shown on the figure 2 , the surname "DURANT" added during the additional customization reveals the hitherto hidden lines. Thus, an attempt to modify and alter the credentials of the holder of the medium can immediately be detected with the naked eye.

However, this solution is limited in the sense that it only detects changes in the so-called white areas of the surface of the support, located around the printed areas, but it does not prevent changes in the various printed areas as on the face of a photograph for example. Therefore, even if this solution avoids the addition of extra hair to a photo, it does not prevent the addition of glasses, whiskers, or the modification of the features of a face by accentuating more or less cheekbones or throwing the complexion for example.

Other solutions consist in adding security elements of the hologram type, information printed with an ink reacting to ultraviolet radiation, hidden micro-letters in an image or text, etc.

These solutions make it possible to securely secure the information media but they require additional equipment and / or equipment generating additional production costs.

Also, the technical problem of the present invention is to provide a secure information medium comprising personalization information arranged on at least one of its main faces, said support further comprising anti-forgery means invisibles disposed on at least a portion of said face and provided to undergo a change of appearance in case of attempted additional customization, which would make immediately visible to the naked eye any fraud attempt by additional customization, whatever the support area, printed or not, in which this additional customization is performed.

The solution to the technical problem is obtained according to the present invention in that the anti-falsification means are formed by a subdivision of each pixel into a matrix of N points, said N points having a different color density from each other to allow obtaining an average color density of said matrix equivalent to a predetermined color density for the corresponding pixel, at least some of said N points of the matrix being pre-sensitized to induce a more or less rapid darkening of their color, in case of additional personalization, compared to other non-pre-sensitized points.

Thus, a printable pixel, visible to the naked eye, is subdivided into a matrix of micro-pixels, also called points throughout the rest of the description, invisible to the naked eye, each point having a color density such that the average color density of the matrix corresponds to a predetermined density for the corresponding pixel. Some of the points are pre-sensitized to react differently in case of additional customization. Thus, if a fraudster tries to modify a photo by adding an overload, the pre-sensitized points of each matrix undergoing this additional customization will react more or less than others and darken more or less quickly. Therefore, depending on the number of points pre-sensitized by matrix and the degree of pre-sensitization of these points, each matrix, or corresponding pixel, will react differently and some pixels will appear darker or lighter than other surrounding pixels. Thus, lines and / or texts and / or logos will appear in lighter shades and / or darker compared to an average color density, in areas where additional customization has been performed.

• subdiviser chaque pixel en une matrice de N points,
• pré-sensibiliser au moins certains desdits N points à une densité de couleur prédéterminée, de sorte que la densité moyenne de la matrice équivaut à une densité prédéterminée pour le pixel correspondant,
• lesdits points pré-sensibilisés étant prévus pour induire un assombrissement plus ou moins rapide que les points non pré-sensibilisés en cas de personnalisation supplémentaire de manière à modifier l'apparence visuelle du pixel correspondant à la matrice.

The invention also relates to a security method, an information carrier comprising personalization information arranged on at least one of its main faces, said support further comprising invisible anti-forgery means arranged on at least a part of said face and provided to undergo a change of appearance in case of attempted additional personalization. The method is remarkable in that the realization of the anti-falsification means comprises the following steps.

• subdivide each pixel into a matrix of N points,
• pre-sensing at least some of said N points to a predetermined color density, so that the average density of the matrix equals a predetermined density for the corresponding pixel,
• said pre-sensitized points being provided to induce more or less rapid darkening than non-pre-sensitized points in case of additional personalization so as to modify the visual appearance of the pixel corresponding to the matrix.

• la figure 1, déjà décrite, une carte d'identification supportant une zone de texte et une photographie originales et une carte falsifiée supportant une zone de texte et une photographie modifiées,
• la figure 2, déjà décrite, un détail de la surface d'un support d'information personnalisé selon un mode de réalisation connu et les effets produits en cas de tentative de falsification,
• la figure 3, un schéma de quatre pixels dits « originaux », et de quatre pixels dits « équivalents » subdivisés en matrices de points pré-sensibilisés conformément à l'invention,
• la figure 4, un schéma des effets produits en cas de tentative de falsification d'un support d'information sécurisé selon l'invention.

Other features and advantages of the invention will appear on reading the following description given by way of illustrative and non-limiting example, with reference to the appended figures which represent:

• the figure 1 , already described, an identification card supporting a text box and a original photograph and a falsified card supporting a modified text box and photograph,
• the figure 2 , already described, a detail of the surface of a personalized information carrier according to a known embodiment and the effects produced in case of attempted forgery,
• the figure 3 a diagram of four so-called "original" pixels, and four so-called "equivalent" pixels subdivided into pre-sensitized dot matrixes according to the invention,
• the figure 4 a diagram of the effects produced in the event of an attempt to falsify a secure information medium according to the invention.

The examples described below relate to substantially rigid identification cards, such as identity cards for example. However, the invention is not limited to this type of card but extends to all kinds of identification object, containing or not electronic components, such as passports or other valuable paper for example.

An information medium generally comprises at least two main surfaces, front and back. Personalization information is arranged on at least one of its main surfaces. It also includes invisible anti-forgery means disposed on at least a portion of the printed face. These anti-forgery means are intended to undergo a change of appearance in case of attempted forgery.

The anti-falsification means can therefore be arranged just on the printed areas of one face or over the entire surface of at least the face supporting the personalization information. They are made by subdivision of each printable pixel, visible to the naked eye, into a matrix of N micro-pixels, invisible to the naked eye.

Throughout the remainder of the description, the term "darkening" is used, in order to simplify the understanding, to designate both a darkening and a lightening. Such darkening or lightening is obtained according to the degree of pre-sensitization of the constituent points of a pixel, that is to say according to their reactivity to the laser beam.

The term "pre-sensitization" is used throughout the rest of the description to designate the constituent points of pixels whose visual appearance is not changed but which may change their appearance during an attempted fraud. Thus, for example, pre-sensitized white pixels at different levels will have different aspects in case of fraud. For gray pixels, we talk about "pre-sensitized" pixels as well as "more reactive" pixels that will become darker or lighter in the case of fraud, compared to an average.

A subdivision of pixels into dot matrices is schematized on the figure 3 . In the example, four pixels P1, P2, P3, P4 are each subdivided into a matrix of N points, or micro-pixels. In the example, each matrix includes N = 25 points, but this number may vary.

Each point Nn of a matrix has a predetermined color density so that the average density of the matrix corresponds to the density chosen for the corresponding pixel P1. In laser printing, there are 256 gray levels, each point has a particular gray level. In the diagram of the figure 3 each point Nn has an integer value corresponding to a density of gray. Thus, for the matrix corresponding to the pixel P1, the average density of the 25 points, N1 to N25, is equal to 8.48. Similarly, for the matrix corresponding to the pixel P2, the average density of the dots is equal to 4.88, for the matrix corresponding to the pixel P3, the average density of the dots is equal to 11.04 and finally for the matrix corresponding to pixel P4, the average density of the dots is equal to 11.04. These four matrices thus each have a predetermined average density of gray perceptible to the naked eye, while each point making up this matrix and contributing to the average value of gray density remains invisible to the naked eye.

The four matrices, or corresponding pixels, referenced P1A, P2A, P3A and P4A, represent the same pixels P1, P2, P3 and P4 after having undergone additional customization to the laser. The gray levels are each more or less sensitive to the laser beam, they do not all react in the same way and some gray levels darken faster than others when subjected to the same laser radiation. Thus, each point of the matrix P1A, respectively P2A, P3A and P4A darkens more or less after being subjected to the laser beam. At the end of this additional personalization, the matrix P1A for example has an average density of 50.24, the matrix P2A has an average density of 43.48 and the matrices P3A and P4A have an average density of 62.88. As a result, the gray density of the first P1A matrix averaged 41.76, that of the second matrix averaged 38.6, and those of the third and fourth matrix averaged 51.76. 84.

To be able to detect additional customization done in a completely fraudulent manner, at least some of the original pixels P1, P2, P3, P4 of the surface to be secured are replaced by so-called "equivalent" pixels P1 ', P2', P3 ', P4' . For this, it pre-sensitizes at least some points of the equivalent matrix, corresponding to the equivalent pixel, so that the average density of gray is equivalent to that of the original matrix, corresponding to the original pixel. In this case, the pre-sensitized points will react differently to the second customization, so that the equivalent matrix after fraudulent additional customization P1'B, P2'B, P3'B and P4'B, will not be equivalent to the matrix. original after additional customization P1A, P2A, P3A, P4A.

Thus, for example in the equivalent matrix P1 ', the points N3, N4, N8, N10, N14, N18, N20, N22 and N24 are pre-sensitized differently from their correspondents in the original matrix P1. The average gray density of the matrix P1 'is equal to 8.28, which is a very close value and considered equivalent to the value 8.48 of the average gray density of the original matrix P1. However, at the end of a fraudulent personalization, the pre-sensitized points do not react in the same way as those of the matrix P1. Thus, the matrix P1'B has a mean gray density equal to 56.84 which is darker than the average density of 50.24 of the matrix P1 '. At the end of the second personalization, the average density of the equivalent matrix P1 'has therefore increased by a value equal to 48.56. Consequently, the pixel P1B ', equivalent corresponding to the matrix, appears darker than the original pixel P1A, with the naked eye.

In the same way, in the example of figure 3 , the equivalent matrices P2'B and P3'B appear darker than the original matrices P2A and P3A after second customization.

The original matrix P4, for its part, is identical to the matrix P3. On the other hand, with equivalent average density value, the equivalent matrix P4 ', whose average equivalent density is equal to 10.96, differs from the equivalent matrix P3', whose average density is equal to 11.12. Indeed, the equivalent matrix P4 'does not have at all the same number of pre-sensitized points or the same level of pre-sensitization as the matrix P3'. Thus, P4 'has fewer points having a gray level more responsive to the laser beam, relative to P3'. Therefore, after further fraudulent customization, the corresponding pixel P4'B darkens much less than the pixel P3'B. The average gray density of the pixel P4'B is equal to 58.68 while the average density of the pixel P3'B is 66.88. In this case, during fraudulent customization, the pixel P4'B will appear brighter than an original non-pre-sensitized pixel P4A, or another pixel P3'B pre-sensitized differently.

This example illustrates the fact that according to the number of pre-sensitized points, and according to their degree of pre-sensitization, that is to say if their gray level is more or less reactive to a laser beam, the corresponding pixel to the matrix will appear more or less dark to the eye. Thus, when the equivalent matrix P1 ', P2', P3 'comprises more points more responsive to the laser beam, the pixel P1'B, P2'B, P3'B appears darker after the second personalization. On the other hand, if the equivalent matrix P4 'comprises fewer points more responsive to the laser beam than the original matrix, then the corresponding pixel appears lighter than the original P4A after the fraudulent personalization.

Thus, each pixel or matrix comprises a certain number of points more or less pre-sensitized so that after submission to a laser beam, the pixels change their appearance and all the pixels thus subjected to the second customization form a pattern predetermined such as lines or text or logo etc ....

Fraudulent personalization can also result in the destruction of a photo. Thus, changing the appearance of the pixels may cause a reduction in the resolution of the photo, also called depixelisation, which consists in reducing the resolution of 300dpi, for example to 50 or 100dpi. This is explained by the appearance of squares in the photo that significantly reduce its sharpness.

The figure 4 illustrates, very schematically, the effects produced in case of fraudulent personalization of a secure card according to the invention. In this figure, the entire surface of the card is secured. Fraud attempts by modifying the photo and adding a surname are immediately visible to the naked eye. Thus, during the attempt to modify the face, darker and lighter bands appeared. When trying to add hair, darker lines 16 types of guilloches appear in the hair added, and finally in the area where the fraudster tried to add a surname, the surname added 11A appears in irregular dashed lines because the pixels constituting alphanumeric characters appear more or less dark or light. Likewise, the modified numbers 14A of the security number appear in much stronger and darker lines than the unchanged digits.

The pre-sensitized points are not necessarily in constant numbers for a selected gray level. This is particularly the case if a different rendering is desired during an attempted fraud. All combinations are therefore possible: different number of pre-sensitized points for the same gray rendering, identical number of pre-sensitized points but different values for a different rendering, etc.

Among the existing gray levels, some are more responsive than others to the laser beam and thus darken faster than others. Among the most reactive levels, a certain number S is chosen. For each of the S gray levels chosen, a number M of points to be pre-sensitized to this Sth gray level is chosen. Finally, we divide the S * M points to pre-sensitize to different levels of gray in a matrix P, so that the average density obtained for the matrix is equivalent to the predetermined density required of the corresponding pixel. This distribution is variable: it can be done completely randomly or fixed.

In the example of the figure 3 thirteen pre-sensitized points are distributed in the matrix P1 ', eight of them have a first gray level of density 10 and five others have a second gray level of density equal to 23. In the matrix P2' eleven points of the same gray level of density 10 are distributed. In the matrix P3 ', eighteen pre-sensitized points are distributed, eleven of them have a first gray level of density 10 and seven others have a second level of gray of density equal to 23. In the matrix P4' , twelve pre-sensitized points are distributed, seven of them have a first gray level of density equal to 10, five others have a second gray level of density equal to 40.

The pre-sensitization of the dots is carried out by means of a laser beam conventionally used for printing information media. The laser used may for example be, but is not limited to, a YAG laser. The laser beam scans each of the N points of each matrix P, and at each gray density change, the energy of the laser beam is adjusted, so that the dot is properly sensitized and has the required gray density. This pre-sensitization of some of the points is advantageously simultaneously with the laser printing of the areas to be printed. Thus, for the pixels to be printed, the average gray density of which is predetermined, the laser beam scans all the points of the corresponding matrix, so that they each have a certain density of gray, some of them being pre- sensitized to a gray level sensitive to laser radiation. At the end of this printing step, each point of each matrix has a gray density such that the average density of the N points is equivalent to the predetermined density of the corresponding pixel to be printed.

In the case where the anti-falsification means are arranged on the entire surface of the information medium, all the N points of each matrix corresponding to each pixel of the surface are scanned by the laser beam. When points are not to be pre-sensitized, and they are in a white area, the laser beam is cut off.

The matrix of points is not organized, since the pre-sensitized points can be randomly distributed in the matrix, a fraudster will have to scan all the N points of the matrix and analyze them. Therefore, the fraud time is multiplied by the number N of points of the matrix. Moreover, the fact of distributing the pre-sensitized points randomly in each matrix means that, from one matrix to another, the pre-sensitized points are never at the same position in the matrix, they are not necessarily at the same number M * S, and they do not necessarily have the same density S of gray. Therefore, a fraudster is obliged to analyze the N points of each matrix, corresponding to a pixel, before making additional customization.

On the other hand, the number N of points per matrix must be chosen judiciously. Indeed, this number must be maximum on the one hand for obtaining an optimum contrast and visible immediately to the naked eye, between the different pixels after fraudulent personalization, and on the other hand to increase by the same time analysis of each pixel in case of fraud. However, it must be minimum for obtaining a time of first personalization reasonable.

According to one variant, the distribution of pre-sensitized points can be determined so as to contain coded information relating to the support or personalization. In this case, the positioning of the pre-sensitized points is judiciously chosen to reveal the coded information during a fraudulent personalization. Thus, for example, on a matrix of nine points, corresponding to an original pixel, two pre-sensitized points will be placed in the matrix so that the combination of this matrix with a neighboring matrix, ie four pre-sensitized points, lets appear an alphanumeric character, for example, in case of additional customization. This code can be repeated in a photograph for example. In this case, it is possible to recover the information by a precise scan of the dark and light parts of the image where these sets of points can be made visible. In this case, the pre-sensitized points have a dual function: they react differently to a new laser printing and also allow to encode information.

The anti-falsification means are undetectable by a simple visual examination of the personalized support. Subsequently, in the event of a fraudulent laser overload attempt on or around the existing customization, the appearance of the pixels will be modified because they will appear lighter or darker, so that they show a predetermined pattern at level of overloads created. This change of appearance appears to the extent that the energy overload received on each pixel exceeds a threshold of energy required to react the points of the pixels and that the change in the overall average density of each pixel is visible to the naked eye.

The example which has just been described is only an illustrative example, and the invention is not limited to this embodiment. Other means than a laser beam can be used both for pre-sensitization and fraudulent personalization, without departing from the scope of the invention. For example, it may be envisaged that a drop of ink sensitive to the laser beam is applied by inkjet or by thermal sublimation on the points to be sensitized.

It is also conceivable that the dots, printed by ink jet or by thermal sublimation (D2T2), for example, are pre-sensitized by adding a drop of varnish which makes it possible to repel more or less a drop of ink subsequently applied. when fraudulent printing by inkjet or thermal sublimation, so that the pixel corresponding to the dot matrix appears lighter or darker than the surrounding pixels. In this case, the concentration of the agent that repels the ink in the applied varnish is varied so that the latter repels more or less the ink drop.

Claims (17)

An information carrier comprising personalization information arranged on at least one of its main faces, said support further comprising invisible anti-forgery means disposed on at least a portion of said face and adapted to undergo a change of appearance in case additional personalization attempt, characterized in that the anti-forgery means is formed by a subdivision of each pixel into a matrix of N points, said N points having a different color density from each other to allow obtaining an average color density of said matrix equivalent to a predetermined color density for the corresponding pixel, at least some (S * M) of said N points of the matrix being pre-sensitized to induce a more or less rapid darkening of their color; case of additional customization, compared to other non-pre-sensitized points. Support according to claim 1, characterized in that said anti-falsification means are arranged on all said face. Support according to claim 1, characterized in that said anti-falsification means are arranged on the printed areas comprising said personalization information. Support according to any one of Claims 1 to 3, characterized in that each matrix comprises a distribution of a predetermined number (M) of pre-sensitized points per predetermined level (S) of reactive color to additional personalization. Support according to claim 4, characterized in that the distribution of the pre-sensitized points is random. Support according to Claim 4, characterized in that the distribution of the pre-sensitized points is chosen so as to contain coded information relating to the support or personalization. Support according to any one of the preceding claims, characterized in that some matrices comprise more pre-sensitized points than other matrices, so that in case of additional customization, some pixels appear darker and others appear more clear that pixels not pre-sensitized. A method of securing an information carrier comprising personalization information arranged on at least one of its main faces, said support further comprising invisible anti-forgery means disposed on at least a portion of said face and intended to undergo a appearance change when trying to customize additional, the realization of anti-forgery means comprising the following steps. subdivide each pixel into a matrix of N points, pre-sensing at least some of said N points to a predetermined color density so that the average density of the matrix equals a predetermined density for the corresponding pixel, said pre-sensitized points being designed to induce a more or less rapid darkening than the non-pre-sensitized points in case of additional personalization so as to modify the visual appearance of the pixel corresponding to the matrix. Method according to claim 8, characterized in that the pre-sensitization is performed on the printed areas comprising said personalization information simultaneously with the printing step. Method according to Claim 8, characterized in that the pre-sensitization is carried out on the entire surface of the support, simultaneously with the step of printing the personalization information. Method according to one of claims 8 to 10, characterized in that the step of pre-sensitization of the points is performed by means of a laser beam which scans the N points of each matrix. Method according to Claim 11, characterized in that the energy of the laser beam is adjusted for each point to be printed or pre-sensitized. Method according to one of Claims 8 to 12, characterized in that the pre-sensitization of the points of a matrix corresponding to a pixel comprises the following steps: - choose a number S of color levels more reactive to the laser beam, for each chosen level S, choose a number M of points to be pre-sensitized, distributing the M * S points to be pre-sensitized in the matrix, so that the average of the color densities of the matrix is equivalent to the predetermined density of the pixel corresponding to the matrix. Method according to Claim 13, characterized in that the M * S points to be pre-sensitized are distributed randomly in the matrix. Process according to Claim 13, characterized in that the M * S points to be pre-sensitized are distributed in a determined manner so as to contain coded information relating to the support or personalization. Process according to one of Claims 8 to 10, characterized in that the step of pre-sensitization of the dots is carried out by applying a drop of varnish intended to repel more or less a drop of ink applied during a additional customization attempt. Method according to Claim 16, characterized in that the pre-sensitization of the points of a matrix corresponding to a pixel comprises the following steps: choose a number S of concentrations of agent repelling the ink in the varnish, for each concentration S chosen, choose a number M of points to be pre-sensitized, distributing the M * S points to be pre-sensitized in the matrix, so that the average of the color densities of the matrix is equivalent to the predetermined density of the pixel corresponding to the matrix.

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