Light-guided security inlays for secure documents

Abstract

A preform for a security document is provided, comprising at least a bottom layer, a central layer and a top layer, wherein the central layer comprises one or more inserted inlays arranged between a first corner and a second corner of a side so as to form a horizontal color coding pattern, the one or more inserted inlays comprising a light-conducting material that can interact with input light entering through at least one window of the preform for a security document and exiting from the one or more inserts, so that the color coding pattern is modified by the interaction between the predetermined input light and the light-conducting material. Furthermore, a method for producing a preform for a security document and a method for operating the preform for a security document in such a way as to ensure a stronger tamper resistance are disclosed.

Description

Technical Field

[0001] The present invention relates to security documents and their manufacture. Background Art

[0002] Due to the latest developments in society and industry, data handling and data processing need to comply with increasingly strict regulations in order to reduce the possibility of tampering with sensitive data. In many applications, sensitive data or information must be stored in a permanent and tamper-proof manner, especially when data or information in non-electronic form, which may be combined with electronically stored data, must be stored in some carrier. For example, credit cards, various cards for health insurance, identification cards, etc. represent corresponding "carriers" in which a large amount of non-electronic information is stored, for example in the form of one or more images, symbols, texts, etc.

[0003] Typically, such information, possibly in combination with electronically stored data, such as a radio frequency identification device (RFID) tag or the like, is provided on the basis of a corresponding carrier, which is referred to hereinafter as a "security document", which must provide a high degree of tamper resistance, thereby making any intentional manipulation of the information stored in the corresponding carrier difficult.

[0004] According to some examples, security documents may include security cards, electronic pass ports, and electronic data pages.

[0005] The security document may be provided in the form of a booklet having several pages, at least one of which is a data page. The data page is usually formed as a stack of individual plastic sheets, such as polycarbonate layers or sheets, which are stacked and cut to the desired size, thereby providing the possibility to insert a corresponding sensitive data carrier, for example in the form of text, images, artwork, symbols, etc. and / or to use one of the layers itself as a carrier of sensitive information. The data page may be provided in the form of a block of material with a highly homogeneous composition, so as to reduce the risk of manipulating the data page in any undesired way.

[0006] The data page may be provided in the form of a smart card. Smart cards are the latest innovation in the family of secure documents, in particular identification cards using the ID-1 format defined in ISO / IEC standard 7810. They feature an integrated circuit (RFID) embedded in the card body, which has components for transmitting, storing and processing data. The data can be transmitted via contacts on the card surface or by electromagnetic fields without using contacts. One of the most important advantages of smart cards is that the data stored on them can be protected from unauthorized access and manipulation, since confidential data stored in the card can only be processed internally by the processing unit of the chip.

[0007] Given the widespread use of security documents and the importance of the data stored therein, there have been many counterfeiting attempts. Counterfeiters can obtain the basic materials for making security documents from normal commercial channels, and with the appropriate equipment they can replicate any type of security card.

[0008] In view of the above, an object of the present invention is to produce a security document in a manner that is difficult to forge. This object is achieved by providing a preform for a security document having an improved color coding pattern that can be identified by visual inspection and is produced by using special materials. Summary of the invention

[0009] The invention is based on the idea of ​​providing a preform for security documents with excellent tamper resistance by introducing an additional security level. The additional security level comprises a color-coded pattern resulting from one or more inlays of special material inserted into the card body, wherein the inlays of the special material are able to interact with a light source. In this way, the user is able to recognize the correct interaction of the special material with the light source and thus confirm that the card has not been counterfeited.

[0010] The preform for a security document represents the core of the security document, formed by a stack of individual plastic sheets of a standard configuration, which can be used by the manufacturer as a starting point for the manufacture of the final security document. After the introduction of at least a portion of the sensitive data into the layer stack, the respective preform of the security document can be heat treated to laminate the various layers, thereby inducing respective reactions between the various surface areas, ultimately resulting in an integral structure which at a later stage may be substantially impossible to separate without causing significant damage and thus without leaving recognizable traces of any kind of tampering attempt.

[0011] According to one embodiment of the present invention, there is provided a preform for a security document, comprising at least a bottom layer, a central layer and a top layer, wherein the central layer comprises one or more inserted inlays arranged between a first corner and a second corner of a first side of the central layer so as to form a horizontal color coding pattern, wherein the one or more inserted inlays comprise a light-conducting material configured to interact with input light entering through at least one window of the preform and exiting from the one or more inserted inlays, such that the color coding pattern is modified by the interaction between the predetermined input light and the light-conducting material.

[0012] This configuration has the advantage that the preform for a security document is provided with an additional level of security, since it also comprises one or more inserted inlays featuring a predetermined color-coded pattern. In this way an additional level of security can be provided, since one or more inserted inlays comprising light-conducting materials are inserted into the central layer of the preform, and thus it will be more difficult for a counterfeiter to find these light-conducting materials, manipulate them and assemble them with other layers of the preform for a security document to produce a fake preform for a security document.

[0013] In the following, a "color-coded pattern" of a single insert inlay is intended not only to indicate a predetermined color, but also a predetermined brightness, a predetermined shape and a predetermined size. Furthermore, a "color-coded pattern" of two or more insert inlays is intended not only to indicate a predetermined color sequence, but also a predetermined configuration of insert inlays with any desired shape, and / or size, and / or mutual position and / or predetermined brightness.

[0014] Hereinafter, the color-coded pattern is defined as horizontal to indicate that one or more inserted inlays are arranged along a horizontal direction between a first corner and a second corner of a first side of the central layer, wherein the corner defines where two sides of the central layer meet.

[0015] For example, a red single insert inlay has a rectangular shape, and the height of the rectangle is equal to the thickness of the central layer of the preform defining the predetermined color-coded pattern.

[0016] For example, two inserted inlays, red and blue respectively, having a rectangular shape with a height of the rectangle equal to the thickness of the central layer of the preform and spaced apart by a distance "d" define a predetermined color coding pattern.

[0017] It will be appreciated that the one or more insert inlays may have any colour, for example they may be red, blue, green, yellow etc. Preferably, the customer may select any desired colour for the one or more insert inlays to meet special requirements.

[0018] It should be understood that the one or more insert inlays may have any shape, such as circular, rectangular, etc.

[0019] Furthermore, two or more insert inlays may be arranged at any predetermined mutual distance, for example they may be arranged in contact with each other or they may be separated. Furthermore, one or more insert inlays may have any predetermined thickness.

[0020] Thanks to the light-guiding technology, the inserted inlays can interact with the predetermined input light entering the card, and they can create an output color-coded pattern that can be detected by the user. The user can then detect the output color-coded pattern by visual inspection and can identify a genuine product or a counterfeit.

[0021] It should be understood that the light guide material may include a translucent material (eg, translucent plastic), a transparent material, or a surface-coated transparent material. In some examples, the light guide material may even include a filter material, such as a filter or a polarizer.

[0022] Depending on the desired interaction between the light guide material and the light source, the predetermined input light may include ambient light, monochromatic light, white light, polarized light, etc.

[0023] In a non-limiting embodiment, one or more insert inlays may be made of a light-conductive material such as a translucent plastic, and the preform may be exposed to visible ambient light, such as white light, so that the output color-coded pattern may have the same color sequence as the initial pattern, but with enhanced brightness.

[0024] In another non-limiting embodiment, if one or more of the inserted inlays are made of a light-conductive material such as a translucent plastic, and if the preform is exposed to a predetermined monochromatic light source, the output color-coded pattern can have a different color sequence relative to the initial pattern. For example, if the two inserted inlays are blue and red, respectively, and a monochromatic green source is used, the output color-coded pattern is cyan and yellow.

[0025] In another non-limiting embodiment, if one or more of the inserted inlays are made of a polarizer material, and if the preform is exposed to a non-polarized light source, the output color-coded pattern comprises polarized light. In another non-limiting embodiment, if one or more of the inserted inlays are made of a filter material that transmits a predetermined wavelength, and if the preform is exposed to a white light source, the output color-coded pattern comprises a color corresponding to the predetermined wavelength.

[0026] In the above embodiments, the output color coded pattern may thus be modified by the interaction of the input light with the light guiding material, while the output color coded pattern may be brighter than the original pattern or it may have a different color sequence or different optical properties.

[0027] According to another embodiment of the invention, there is provided a preform for a security document wherein one or more insert inlays comprise a light-conductive material that interacts with visible ambient light such that the brightness of the color-coded pattern is enhanced upon exposure to the visible ambient light.

[0028] The advantages of this construction are ease of production and ease of use, since the color-coded pattern formed on the central layer of the preform for a security document is the same before and after exposure to visible ambient light. Nevertheless, a stronger level of security is provided to the preform, since after exposure to visible ambient light the user will observe an increased brightness of the color of the inserted inlay.

[0029] According to a more illustrative embodiment, the light guide material may be a translucent plastic or a transparent plastic material having any desired color (eg, red, blue, etc.).

[0030] According to another embodiment of the present invention, a preform for a security document is provided, wherein one or more insert inlays include a light-conducting material that interacts with a predetermined input light having a predetermined wavelength or a predetermined polarization such that an output color-coded pattern resulting from exposure to the predetermined input light is different from a color-coded pattern resulting from exposure to visible ambient light.

[0031] This configuration is advantageous because an even stronger level of security is added to the preform, as a user can detect the output color-coded pattern of the preform after exposure to a predetermined light source and can immediately check whether the output color-coded pattern corresponds to the expected modification pattern, thereby proving that the preform is authentic.

[0032] In some embodiments, the predetermined light source may include a light source emitting light at a single predetermined wavelength, such as a monochromatic laser, or may include a light source having a predetermined wavelength obtained by using an optical filter. For example, the predetermined light source may include a polarized light source or a non-polarized light source.

[0033] For example, when exposed to visible ambient light, the two inserted inlays appear blue and red, respectively, and if a monochromatic green source is employed, the output color coding pattern may be cyan and yellow. The user may then confirm whether the output color coding pattern comprising the cyan-yellow color sequence is correct, and may therefore prove whether the preform for a security document is authentic. According to another embodiment of the present invention, a preform for a security document is provided, wherein the light-conducting material comprises an optical fiber.

[0034] An advantage of this configuration is that input light can travel through the optical fiber from one side of the preform to the other, and radiation losses can be minimized.

[0035] According to another embodiment of the present invention, a preform for a security document is provided, wherein a window is arranged on the upper surface of the top layer, and the window is configured such that input light can enter the preform for a security document and reach the light guiding material.

[0036] This configuration is particularly advantageous because it facilitates the handling of the preform for security documents. In fact, exposing the card to an ambient light source, such as a ceiling light, without tilting the card is sufficient to see the output light coming out of the inserted inlay.

[0037] In some embodiments, a preform for a security document may include a plurality of windows.

[0038] According to a more illustrative embodiment, one or more windows are disposed on the upper surface of the top layer of the preform, and they are configured such that input light can travel through the windows and reach the light guide material without encountering any obstacles along its optical path.

[0039] According to another embodiment of the present invention, a preform for a security document is provided, wherein a window is arranged on at least one side of the central layer, and the window is configured such that input light can enter the preform for a security document and reach the light-conducting material.

[0040] The advantage of this configuration is that the preform for a security document can be easily handled, since it can be arranged near the light source in such a way that the input light enters from one or more sides of the card and the output light is detected on the other side of the card. Furthermore, since the window and the one or more inserted inlays are located on the same layer, the input light does not need to travel through the dividing plane between the different layers, where the input light would be refracted, thus minimizing the radiation loss of the input light in the optical path.

[0041] In some embodiments, multiple windows may be provided on a card.

[0042] According to a more illustrative embodiment, one or more windows are provided on one or more sides of the central layer of the preform and are configured such that input light can travel through the windows and reach the light guide material without encountering any obstacles along its optical path.

[0043] According to another embodiment of the invention, a preform for a security document is provided, wherein the window is arranged on an opposite side of the central layer relative to the first side.

[0044] This configuration is particularly advantageous because the preform can be easily manipulated. In fact, the user can arrange the preform near the light source in such a way that the input light travels through one side of the preform and the output light exits from the opposite side. In this way, the user does not need to tilt the preform to see the output light, but can, for example, place the preform in front of the user himself.

[0045] According to another embodiment of the invention, a preform for a security document is provided, wherein the window is arranged on an adjacent side of the central layer relative to the first side.

[0046] This configuration is particularly advantageous because if the input side is adjacent to the output side, the user can see the input light and the output light at the same time and control the operating conditions to be correct.

[0047] According to another embodiment of the invention, a preform for a security document is provided, wherein the one or more inserted inlays have a thickness equal to or less than the total thickness of the central layer.

[0048] This configuration is particularly advantageous since it enables obtaining insert inlays having different sizes, thus increasing the number of possible configurations for the color-coded pattern.

[0049] In some embodiments, one or more inserted inlays may have a thickness equal to half the thickness of the central layer.

[0050] According to another embodiment of the invention, a security document is provided, wherein the security document comprises a preform according to one of the above embodiments.

[0051] This configuration has the advantage that a user can detect the output color-coded pattern by visual inspection and thereby identify an authentic security document or a counterfeit security document.

[0052] According to another embodiment of the present invention, a security document is provided, wherein the security document comprises a preform according to one of the above embodiments, and the central layer of the preform further comprises a chip, and the security document is a smart card.

[0053] This configuration has the advantage that a user can detect the output color-coded pattern by visual inspection, thereby identifying an authentic smart card or a counterfeit smart card.

[0054] According to another embodiment of the present invention, there is provided a method for producing a preform for a security document, wherein the method comprises producing a preform for a security document, comprising providing the preform for a security document with a bottom layer, a central layer and a top layer, and laminating the bottom layer, the central layer and the top layer together to form the preform for a security document, and the method further comprises the following steps:

[0055] a) providing at least one window on one or more of the bottom layer, the middle layer or the top layer;

[0056] b) providing one or more insert inlays and arranging them between the first corner and the second corner of the first side of the central layer so as to form a horizontal color-coded pattern;

[0057] Wherein the one or more inserted inlays include a light-conducting material configured to interact with input light entering through the window and exiting from the one or more inserted inlays such that the color-coded pattern is modified by the interaction between the predetermined input light and the light-conducting material.

[0058] The advantage of this configuration is that an additional level of security is provided to the preform for security documents, since the preform for security documents also contains a color-coded pattern defined by a sequence of light-conducting materials that can interact with light and can have a predetermined color, shape, size and / or position. The output color-coded pattern is thus modified by the predetermined input light that interacts with the light-conducting material, and the output color-coded pattern can be brighter than the original pattern, or it can have a different color sequence or different optical properties.

[0059] Depending on the desired interaction between the light guide material and the light source, the predetermined input light may include ambient light, monochromatic light, white light, polarized light, etc.

[0060] In this way, the risk of counterfeiting preforms for security documents is further reduced, because the light-conducting material inserted into the preform is difficult to find and difficult to process (for example, it is difficult to accurately connect an inserted inlay made of light-conducting material to other layers of the preform), so it is not easy for a counterfeiter to obtain the light-conducting materials and manipulate them to counterfeit preforms for security documents.

[0061] According to a more illustrative embodiment, a preform for a security document is manufactured by assembling together a bottom layer, a central layer and a top layer, and by preparing in parallel a portion of light-conducting material including one or more inserted inlays. Preferably, the top layer is provided with a window having the same shape and size as the portion of light-conducting material that must be inserted into the preform. The portion of light-conducting material is then inserted from the top into a corresponding window on the top layer to reach a predetermined position on the central layer. After the insertion of the portion of light-conducting material, the bottom layer, the central layer and the top layer are laminated together to form a preform for a security document. Finally, a functional test is performed to confirm that the card has been correctly assembled.

[0062] According to another more illustrative embodiment, the central layer can be provided with a window having the same shape and size as the portion of light-conducting material that must be inserted into the preform. In some embodiments, the portion of light-conducting material can thus be inserted through a window configured on either side of the central layer to reach a predetermined position on the central layer.

[0063] According to another embodiment of the invention, a method for producing a preform for a security document is provided, wherein one or more insert inlays are formed by corresponding cut-outs of a light-conducting material.

[0064] An advantage of this configuration is that the light guide material can be easily processed and inserted into the preform.

[0065] According to another embodiment of the present invention, a method is provided in which a single insert inlay is provided and cut to have the same shape as the window of the preform and inserted into the preform through the window.

[0066] This configuration is advantageous because a single insertion inlay made of light-guiding material has the same shape as the input light window and can advantageously be inserted through the window without requiring any further steps for insertion.

[0067] According to another embodiment of the present invention, a method is provided wherein two or more insert inlays are provided and joined together to form a sheet of multicolor lightguide material comprising a horizontal color-coded pattern, and the sheet of multicolor lightguide material is cut to have a predetermined shape.

[0068] This configuration is advantageous because by bonding together two or more insert inlays to form a multi-coloured sheet of light-guiding material, an independent unit of light-guiding material is obtained. During assembly, this unit can be handled separately from the other components of the preform for a security document.

[0069] According to another embodiment of the present invention, a method for producing a preform for a security document is provided, wherein a sheet of multi-color light-guiding material is cut to have the same shape as a window and inserted into the preform through the window.

[0070] This configuration is advantageous because the individual units of multi-color light guide material have the same shape as the input light window and can advantageously be inserted through the window without requiring any further steps for insertion. Preferably, the sheets of multi-color light guide material are cut using a punching tool.

[0071] According to another embodiment of the present invention, there is provided a method for producing a preform for a security document, wherein a sheet of multi-color light-guiding material is formed by thermal lamination.

[0072] This construction is advantageous because the materials are laminated together to form a separate unit of light guiding material.

[0073] According to another embodiment of the invention, a method for producing a preform for a security document is provided, wherein individual insert inlays and / or sheets of multi-color light-guiding material are cut to have a thickness equal to or less than the thickness of the central layer.

[0074] This configuration is particularly advantageous because it enables one or more insert inlays to be obtained having different sizes, thus increasing the number of configurations that can be used for the color-coded pattern.

[0075] According to another embodiment of the present invention, there is provided a method for handling a security document comprising a preform according to any of the above embodiments, wherein the method comprises the following steps:

[0076] a) exposing the security document to a light source such that the window receives a predetermined input light;

[0077] b) detecting the resulting color-coded pattern; and

[0078] c) comparing the resulting color coded pattern with a reference color coded pattern to prove the authenticity of the security document.

[0079] An advantage of this embodiment is that a security document which has been forged can be identified by visual inspection.In practice, it is sufficient to expose the security document to a light source so that the window receives the input light, detect the resulting color coding pattern and compare it with a known reference color coding pattern.

[0080] For example, if the resulting color-coded pattern does not show increased brightness relative to the initial pattern after exposure to an ambient light source, such as white light, a user may immediately recognize that the security document does not contain the required light-conductive material and may immediately recognize that the security document is not authentic.

[0081] For example, if after exposure to a monochromatic light source having a predetermined wavelength, the resulting color-coded pattern does not show an output color-coded pattern that is different from the initial pattern but has a predetermined known sequence, the user can immediately recognize that the security document does not contain the required photoconductive material and can immediately recognize that the security document is not authentic.

[0082] According to another embodiment of the invention, a method for handling a security document comprising a preform according to any of the above embodiments is provided, wherein the reference color coding pattern may have the same color sequence as the color coding pattern and it may have a stronger brightness.

[0083] This configuration is advantageous because it is sufficient to expose the preform for security documents to ambient light to detect the color-coded pattern on one side of the preform. The resulting color-coded pattern is expected to be identical to the original color-coded pattern, but with enhanced brightness. The resulting color-coded pattern can be compared with the original color-coded pattern, and if it corresponds to what the user expected, the quality of the card is proven and counterfeiting can be excluded.

[0084] According to another embodiment of the invention, a method for operating a security document is provided, wherein the reference color coding pattern has a predetermined color sequence, which may be different from the color sequence of the color coding pattern.

[0085] This configuration is advantageous because the preform for a security document is first exposed to a predetermined light source, for example a light source with a predetermined wavelength, and then the corresponding color-coded pattern is detected. The resulting color-coded pattern is compared with the original color-coded pattern, and if it corresponds to what the user expected, the quality of the card is proven and counterfeiting can be excluded.

[0086] In some embodiments, the security document may be exposed to a non-polarized light source and the one or more inserted inlays may include a polarizer material. If the resulting color-coded pattern includes polarized light, the user may recognize that the security document actually includes one or more polarizer inserted inlays and may recognize that the security document is authentic.

[0087] In some other embodiments, the security document may be exposed to a white light source, and one or more inserted inlays may include a filter material that transmits a predetermined wavelength. If the resulting color-coded pattern includes a color corresponding to the predetermined wavelength, a user may recognize that the security document actually includes one or more inserted inlays that include filters, and may recognize that the security document is authentic. BRIEF DESCRIPTION OF THE DRAWINGS

[0088] The present invention will be described with reference to the accompanying drawings, in which like reference numerals and / or symbols designate like parts and / or similar and / or corresponding parts of the machine. In the drawings:

[0089] Figure 1 A top view of an example of a smart card according to the prior art is schematically illustrated.

[0090] Figure 2 A top view of a preform for a security document according to an embodiment of the invention is schematically illustrated.

[0091] Figure 3A , Figure 3B , Figure 3C and Figure 3D Examples of preforms for security documents according to different embodiments of the invention are schematically illustrated.

[0092] Figure 4 The process of forming a sheet of multi-color light guide material having a predetermined shape according to an embodiment of the present invention is schematically illustrated.

[0093] Figure 5 There is schematically illustrated a process of assembling a preform for a security document according to a more illustrative embodiment of the invention. DETAILED DESCRIPTION

[0094] In the following, the present invention is described with reference to the specific embodiments shown in the accompanying drawings. However, the present invention is not limited to the specific embodiments described in the following detailed description and shown in the accompanying drawings, but on the contrary, the embodiments only illustrate several aspects of the present invention by way of example, and the scope of the present invention is defined by the appended claims.

[0095] Further modifications and variations of the present invention are clear to those skilled in the art. Therefore, this specification must be considered to include all modifications and / or variations of the present invention, and the scope of the present invention is defined by the appended claims.

[0096] For simplicity, the same or corresponding components are marked with the same reference numerals in the drawings.

[0097] Figure 1 A top view of a smart card 200 according to the prior art is schematically shown. The smart card 200 comprises a card body 210, a chip 220 and an interconnect substrate for the chip and the card body. The interconnect substrate serves as a support for the chip and comprises conductors that provide communication between the chip and the external environment. The card body is preferably made of polyvinyl chloride (PVC) or polycarbonate.

[0098] Figure 2 Schematically illustrates a top view of a preform 100 for a security document according to an illustrative embodiment of the present invention. In particular, Figure 2 The preform 100 for a security document is shown when exposed to a light source.

[0099] The preform 100 comprises at least a bottom layer, a central layer and a top layer. The central layer 120 may comprise two inserted inlays 151 and 152 arranged between a first corner 122 and a second corner 123 of a first side 121 of the central layer 120 so as to form a horizontal color-coded pattern 150. The horizontal color-coded pattern 150 depends not only on the color sequence of the two inserted inlays 151 and 152, but also on their shape (e.g. rectangular or circular), size (e.g. thickness) and mutual position (e.g. distance between the inserted inlays 151 and 152). The number of inserted inlays is not limited to two, but may instead be one, three, four or more.

[0100] It will be appreciated that any color coded pattern may be created on the output surface of the central layer of the preform 100, and therefore of the security document, depending on the specific needs of the customer.

[0101] Figure 2The inserted inlays 151 and 152 have a thickness T1 that is less than the total thickness T2 of the central layer 120 of the card. However, it should be understood that the thickness T1 of the inserted inlays 151 and 152 may also be equal to the thickness T2 of the central layer 120 of the card.

[0102] The two insert inlays 151 and 152 comprise a light guide material 140 which can interact with input light from a light source, such as a visible ambient light source or a light source having a predetermined wavelength. The light guide material can comprise, for example, a translucent plastic material, a transparent plastic material or a surface coated plastic material.

[0103] Since the window is configured on the upper surface of the top layer of the preform 100, interaction between the light guide material 140 and the light source is possible. Therefore, light can enter the preform through the window 131, then reach the light guide material 140 without encountering any obstacles, and leave through the insert inlays 151 and 152.

[0104] However, it should be understood that a preform comprising a plurality of windows 131 is also possible.

[0105] The light guide material is configured to interact with input light entering the card through the window 131. The output light then forms an output color coded pattern associated with the light guide material 140 and the specific light source. If the insert inlays 151 and 152 include a predetermined light guide material 140, and the light source is visible ambient light, such as white light, the output color coded pattern may feature a color sequence given by the colors of the two insert inlays 151 and 152, but with increased brightness. If the insert inlays 151 and 152 include a predetermined light guide material 140, and the light source is a monochromatic light source with a predetermined wavelength, the output color coded pattern may feature a predetermined color sequence different from the colors of the two insert inlays 151 and 152. Preferably, the bottom layer of the preform includes a reflective layer to prevent radiation loss from the bottom of the card.

[0106] The monochromatic light source may be a light source emitting light at a predetermined wavelength, such as a monochromatic laser, or it may be a monochromatic light source obtained with a filter. In addition, the monochromatic light source may be polarized or non-polarized depending on the predetermined light-guiding material.

[0107] FIG. 3A to FIG. 3D A preform 100 is schematically illustrated, defining different color-coded patterns, according to an illustrative embodiment of the present invention.

[0108] Figure 3AA preform 100 according to the present invention is shown, which comprises a bottom layer 110, a central layer 120 and a top layer 130. A window 131 is arranged on an upper surface 132 of the top layer 130 of the preform 100. Input light can travel into the preform through the window 131. The window 131 is shown as having a circular shape; however, it is clear that it can have any shape, i.e., square or rectangular.

[0109] The preform is designed so that input light entering the window 131 travels through the light-guiding material 140 inserted within the central layer 120 and exits through the insert inlays 151 and 152. The two insert inlays 151 and 152 are shown at a distance such that there is a common edge between the two insert inlays 151 and 152. However, it is apparent that the two insert inlays may be configured at any preferred mutual distance. Furthermore, the two insert inlays 151 and 152 are shown as having the same thickness T1, but they may have different thicknesses. Furthermore, the two insert inlays 151 and 152 are shown as having the same thickness T1 as the total thickness of the central layer 120, but they may also have a thickness T1 that is less than the total thickness of the central layer 120.

[0110] Figure 3B Another embodiment of the present invention is schematically illustrated, showing a preform 100 for security documents, comprising a bottom layer 110, a central layer 120 comprising a window, and a top layer 130. In this configuration, input light can enter the preform 100 for security documents through a window (not shown) arranged on one side of the card, in particular the side opposite to the side 121 where the two insert inlays 151 and 152 are located. The input light travels through the preform 100 from one side to the other and exits from the side 121 of the central layer 120 where the translucent insert inlays 151 and 152 are located.

[0111] The two insert inlays 151 and 152 are shown as being spaced apart from each other by a distance d. However, it is obvious that the two insert inlays can be arranged at any preferred mutual distance, and they can also be in contact with each other. Furthermore, any thickness of the two insert inlays 151 and 152 is possible.

[0112] Figure 3CA preform 100 according to an embodiment of the present invention is schematically illustrated, comprising a bottom layer 110, a central layer 120 comprising a window 125, and a top layer 130. The window 125 is arranged on one side of the central layer 120 of the preform 100, in particular on a side 127 adjacent to the side 121 where two insert inlays 151 and 152 are arranged. In this configuration, input light enters the preform 100 through the window 125, travels through the light guide material 140 and exits through the two insert inlays 151 and 152. In this way, it is apparent that in an operating condition, a user can rotate the preform 100 so as to simultaneously see the input light entering the preform 100 through the window 125 and the output light exiting the preform 100 through the two insert inlays 151 and 152.

[0113] The two inserted inlays 151 and 152 are shown one next to the other and also in contact with the window 125. However, it is obvious that the two inserted inlays 151 and 152 and the window 125 can be arranged at any preferred mutual distance. In addition, any thickness of the two inserted inlays 151 and 152 and the window 125 is possible.

[0114] Figure 3D A preform 100 according to a preferred embodiment of the present invention is schematically illustrated. The preform 100 comprises a bottom layer 110, a central layer 120 comprising a window and a top layer 130, and an input light window (not shown) is arranged on one side of the central layer 120, in particular on the opposite side relative to the side 121 where the insert inlays 151 and 152 are arranged. The insert inlays 151 and 152 are shown to have a circular shape. This configuration can be advantageously applied in combination with an optical fiber used as a light-guiding material 140, wherein the diameter of the insert inlays 151, 152 is equal to the diameter of the optical fiber and corresponds to the total thickness T2 of the central layer 120, so as to prevent energy loss. In this configuration, the optical fibers connect one side 121 of the preform 100 to the opposite side, and they transmit the input light with minimal radiation loss.

[0115] Under operating conditions, including according to FIG. 3A to FIG. 3D The security document, such as a smart card, of the illustrated illustrative embodiment of the preform 100 is exposed to a light source, such as a visible ambient light source or a monochromatic light source. The luminous pattern formed on the side 121 where the two insert inlays 151 and 152 are located is detected by visual inspection by a user.

[0116] When ambient light sources are employed, the luminous pattern may feature a color sequence and increased brightness that is related to the color sequence of the two inserted inlays 151 and 152. Thus, a user may recognize the increased brightness in the output color coded pattern and be assured that the security document is authentic.

[0117] When a predetermined monochromatic light source is employed, the luminescent pattern may feature a predetermined color sequence that is different from the color coding sequence of the two inserted inlays 151 and 152. By detecting the output color coding pattern and knowing the expected predetermined color coding pattern, a user can immediately identify a counterfeit by visual inspection.

[0118] Figure 4 The process for forming a unit of light-conducting material to be inserted into a preform 100 for a security document is schematically illustrated. The unit of light-conducting material may be made by assembling together three cut-out portions 151, 152 and 152' of three corresponding light-conducting materials (e.g. materials of different colors). The three portions 151, 152 and 152' may be laminated together to form a single sheet of light-conducting material 153. The sheet of light-conducting material 153 is then cut into different portions of predetermined sizes. For example, each portion of the sheet of light-conducting material 153 may have the same size as the window of the preform 100 for a security document to facilitate insertion. The sheet of light-conducting material 153 is preferably cut into predetermined portions using a punching tool.

[0119] Obviously, even though three cut-outs of light-conducting material are shown, any number of cut-outs of light-conducting material is possible, such as one, two, four, five or more cut-outs of light-conducting material. If a single cut-out of lightweight material is inserted into the preform 100 for a security document, it is preferably cut to have the same dimensions as the window of the preform 100 for a security document to facilitate insertion.

[0120] refer to Figure 5 A method for producing a preform 100 for a security document according to an embodiment of the present invention is described.

[0121] The preform 100 for a security document may initially be prepared in a standard manner by assembling together the first two layers, the bottom layer 110 and the central layer 120. In the case where a smart card is desired, an electronic chip is also inserted into the preform, for example into the central layer 120. Preferably, functional testing is performed to ensure correct operation of the chip.

[0122] As reference Figure 4 As described above, a cut-out portion of the light guide material sheet 153 is formed. Preferably, the cut-out portion of the light guide material sheet 153 is formed to have the same shape as the window 131 of the top layer 130 of the preform 100. Accordingly, the top layer 130 of the preform 100 is prepared to have a window 131 cut out on the upper surface 131. However, it is obvious that the cut-out portion of the light guide material sheet may also have the same shape as the window of the central layer 120 of the preform. In this case, the central layer 120 of the preform 100 is prepared to have a cut-out window 125 on any side thereof.

[0123] In reference Figure 5 In the illustrated embodiment, the top layer 130 including the window 131 is assembled to the previously assembled bottom layer 110 and the central layer 120. The cut-out portion of the light guide material sheet 153 is inserted into the preform through the window 131 on the upper surface of the top layer 130 so as to be arranged at a desired position. Therefore, it is obvious that if a window is cut out on one side of the central layer 120, the cut-out portion of the light guide material sheet 153 is inserted through the window so as to reach a predetermined position in the central layer 120.

[0124] Once all the layers have been assembled, they are laminated together to form a whole. Preferably, a functional test is performed to check the correct assembly of the preform. If the preform is produced for a smart card, a functional test is preferably performed to confirm the correct operation of the chip.

[0125] While the present invention has been described with respect to a preferred physical embodiment constructed in accordance with the invention, it will be apparent to those skilled in the art that various modifications, variations and improvements may be made to the present invention in light of the above teachings and within the scope of the appended claims without departing from the spirit and intended scope of the invention.

[0126] For example, even though it has been described that the window for letting input light into the preform for security documents is provided on the top layer, it is clear that it can also be provided on the bottom layer, since the preform has no preferred orientation. For example, even though a preferred configuration of insert inlays 151 and 152 is given, it is clear that any color, position, shape and size of insert inlays 151 and 152 is possible, and if two or more insert inlays are provided, they do not have to have the same shape or size.

[0127] For example, the two inserted inlays 151 and 152 may have the same thickness as the total thickness of the central layer 120 of the preform 100, or they may have a thickness less than the total thickness of the central layer 120 of the preform 100. Furthermore, the two inserted inlays 151 and 152 may be configured at any predetermined distance from each other to create any desired optical effect on the output color-coded pattern.

[0128] For example, it should be understood that the positions of the two inserted inlays 151 and 152 can be shifted relative to the position of the input window 125 or 131 as long as the input light can reach the light guide material 140 without encountering any obstacles and form the output color coding pattern.

[0129] Even though it is not shown in the figures, it must be understood that the positions of the two insert inlays 151 and 152 can also be aligned with the input window 131 of the preform 100 when the window 131 is arranged on the top layer 130 of the preform 100 .

[0130] Description of Reference Numerals

[0131] 100: Preforms for security documents

[0132] 110: Bottom

[0133] 120: Central level

[0134] 121: First side of the central layer

[0135] 122: First corner of first side

[0136] 123: Second corner of first side

[0137] 125: Window on the central floor

[0138] 126: Second side of the central layer

[0139] 127: The third side of the central layer

[0140] 130: Top floor

[0141] 131: Window on the top floor

[0142] 132: Top surface of the top layer

[0143] 140: Optical guide materials

[0144] 150: Color coded pattern

[0145] 151, 152, 152': Insertion inlay

[0146] 153: Multicolor light guide material sheet

[0147] 200: Security File

[0148] 210: Smart card body

[0149] 220: Chip for smart card

Claims

1. A preform (100) for a security document, comprising at least a bottom layer (110), a central layer (120) and a top layer (130), Features: The central layer (120) comprises one or more inserted inlays (151, 152) arranged between a first corner (122) and a second corner (123) of a first side (121) of the central layer (120) so as to form a color-coded pattern (150) along a direction extending between the first corner (122) and the second corner (123), wherein the one or more insert inlays (151, 152) include a light-conducting material (140) configured to interact with input light entering through at least one window (125, 131) of the preform (100) and exiting from the one or more insert inlays (151, 152), such that the color-coded pattern (150) is modified by an interaction between a predetermined input light and the light-conducting material (140).

2. The preform (100) for a security document according to claim 1, wherein the light-conducting material (140) is configured to interact with visible ambient light in such a way that the brightness of the color-coded pattern (150) is enhanced after exposure to the visible ambient light.

3. A preform (100) for a security document according to claim 1, wherein the light-conducting material (140) is configured to interact with a predetermined input light having a predetermined wavelength or a predetermined polarization in such a way that an output color-coded pattern (150) resulting from exposure to the predetermined input light is different from a color-coded pattern (150) resulting from exposure to visible ambient light.

4. The preform (100) for a security document according to any one of claims 1 to 3, wherein the light-conducting material (140) comprises optical fibers.

5. The preform (100) for a security document according to any one of claims 1 to 3, wherein the window (131) is arranged on an upper surface (132) of the top layer (130), and the window (131) is constructed so that the input light can enter the preform (100) for a security document and reach the light-conducting material (140).

6. The preform (100) for a security document according to any one of claims 1 to 3, wherein the window (125) is arranged on at least one side (126, 127) of the central layer (120), and the window (125) is constructed so that the input light can enter the preform (100) for a security document and reach the light-conducting material (140).

7. Preform (100) for a security document according to claim 6, wherein the window (125) is arranged on the opposite side (126) of the central layer (120) relative to the first side (121).

8. Preform (100) for a security document according to claim 6, wherein the window (125) is arranged on an adjacent side (127) of the central layer (120) relative to the first side (121).

9. The preform (100) for a security document according to any one of claims 1 to 3, wherein one or more of the one or more insert inlays (151, 152) has a thickness (T1) equal to or less than the total thickness (T2) of the central layer (120).

10. A security document (200) comprising the preform (100) for a security document according to any one of the preceding claims 1 to 9.

11. The security document (200) according to claim 10, wherein the central layer (120) of the preform further comprises a chip (220), and the security document (200) is a smart card.

12. A method for producing a preform (100) for a security document, the method comprising providing a bottom layer (110), a central layer (120) and a top layer (130), and laminating the bottom layer (110), the central layer (120) and the top layer (130) together to form the preform (100) for a security document, It is characterized in that The method further comprises the following steps: a) providing at least one window (125, 131) on one or more of the bottom layer (110), the central layer (120) or the top layer (130); b) providing one or more insert inlays (151, 152) and arranging the one or more insert inlays between a first corner (122) and a second corner (123) of a first side (121) of the central layer (120) so as to form a color-coded pattern (150) along a direction extending between the first corner (122) and the second corner (123), The one or more insert inlays (151, 152) include a light-conducting material (140) configured to interact with input light entering through the windows (125, 131) and exiting from the one or more insert inlays (151, 152), such that the color-coded pattern (150) is modified by an interaction between a predetermined input light and the light-conducting material (140).

13. Method for producing a preform (100) for a security document according to claim 12, wherein the one or more insert inlays (151, 152) are formed by corresponding cut-outs of the light-conducting material (140).

14. A method for producing a preform (100) for a security document according to claim 12 or 13, wherein the one or more insert inlays (151, 152) include a single insert inlay, and the single insert inlay is cut to have the same shape as the window (125, 131), and the single insert inlay is inserted into the preform through the window (125, 131).

15. A method for producing a preform (100) for a security document according to claim 14, wherein there are two or more insert inlays (151, 152), which are combined together to form a multi-color light-conducting material sheet (153) including a horizontal color-coded pattern (150), and the multi-color light-conducting material sheet (153) is cut to have a predetermined shape.

16. A method for producing a preform (100) for a security document according to claim 15, wherein the sheet (153) of multi-color light-conducting material is cut to have the same shape as the window (125, 131) and inserted into the preform through the window (125, 131).

17. A method for producing a preform (100) for a security document according to claim 15, wherein said sheet (153) of multi-coloured light-guiding material is formed by thermally laminating said insert inlays (151, 152) together.

18. Method for producing a preform (100) for a security document according to claim 15, wherein the single insert inlay or the multi-color light-conducting material sheet (153) is cut to have a thickness (T1) equal to or less than the thickness (T2) of the central layer (120).

19. A method for operating a security document (200) according to claim 10 or 11, said method The following steps are involved: a) exposing the security document (200) to a light source such that the window (125, 131) receives the predetermined input light; b) detecting the resulting color-coded pattern (150); and c) comparing the obtained color-coded pattern (150) with a reference color-coded pattern to prove the authenticity of the security document (200).

20. Method for operating a security document (200) according to claim 19, wherein the reference colour-coded pattern has the same colour sequence as the colour-coded pattern (150), but with a stronger brightness.

21. A method for operating a security document (200) according to claim 19, wherein the reference color-coding pattern has a predetermined color sequence which is different from the color sequence of the color-coding pattern (150).

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