Personalizable security document and method of personalizing the same

Abstract

A personalizable security document (10) includes a security feature which has a metallic layer (4) configured to have a first personalized image (5a) laser-engraved in the same. A laser-engravable material (6), which exhibits a color-change effect upon irradiation with laser light (L), is embedded in the security document (10) below the metallic layer (4). Using the laser light (L), the first personalized image (5a) and a second personalized image (5b) can be simultaneously engraved in the metallic layer (4) and the laser-engravable material (6) using appropriate laser parameters. The combination of the metallic layer (4) and the laser-engravable material (6) results in that a switch from a metallic image to a non-metallic image can be obtained when a mode of observation of the security document (10) is changed from reflection to transmission.

Description

Technical Field

[0001] The present disclosure generally relates to security features for security documents, in particular, personalizable security documents such as identification documents, driver's licenses and the like.Background

[0002] Generally, in the market of physical identification documents, a variety of different security features are used to ensure the document's security and integrity. In some applications, a laser-engraved image is considered vital, as the image features are generated inside a polycarbonate substrate rather than on the surface of the substrate, making it more difficult to tamper with the document. A laser-engraved feature in a polycarbonate substrate may include a black and white (in particular, grayscale) image, a color image, or special features like the Mirage security feature of HID.

[0003] WO 2022 / 248309 A1 discloses a personalizable security document including a combination of a plurality of different features. In particular, a laser-engraved image is provided in a first layer of the security document, and one or more fluorescent inks are provided in further layers of the same. A laser-engraving of the image is performed from a first side of the substrate, such that patterns formed by the fluorescent inks are not affected. Under white light, the laser-engraved image can be viewed from the first side, whereas a multi-color fluorescence of the patterns can be observed from a second side under UV light.

[0004] The present disclosure is directed, at least in part, to improving or overcoming one or more aspects of prior systems, without being limited to a particular type of security document.Summary of the Disclosure

[0005] According to one aspect of the present disclosure, a personalizable security document has a substrate having a first side and a second side opposite to the first side in a thickness direction of the substrate, and a security feature formed in the substrate and extending through at least part of the substrate along the thickness direction. The security feature includes a metallic layer configured to have a first personalized image laser-engraved in the same. The metallic layer exhibits a change in reflectivity upon irradiation with laser light and is visible when the substrate is viewed from the first side under white light. The security feature further includes a laser-engravable material configured to have a second personalized image laser-engraved in the same. The laser-engravable material exhibits a color-change effect upon irradiation with the laser light. The laser-engravable material is embedded in the substrate below the metallic layer and overlaps the same at least in part when viewed along the thickness direction such that the second personalized image is formed together with the first personalized image upon the irradiation of the laser light onto the metallic layer from the first side.

[0006] In another aspect of the present disclosure, a method of personalizing a security document includes the steps of providing a personalizable security document in accordance with the above aspect, and simultaneously laser-engraving the first personalized image and the second personalized image from the first side in the metallic layer and the laser-engravable material, respectively, by varying one or more laser parameters. Preferably, the laser parameters include one or more of a laser wavelength between 530 nm and 1060 nm, a laser speed between 100 mm / s and 4000 mm / s, and a laser repetition rate between 50 kHz and 100 kHz.

[0007] Other features and aspects of the present disclosure will be apparent from the following description and the accompanying drawings.Brief Description of the Drawings

[0008] Fig. 1 shows a plan view of an exemplary personalizable security document in accordance with the present disclosure, Fig. 2 shows a cross-section of a personalizable security document in accordance with the present disclosure, Fig. 3 shows individual layers of a personalizable security document in accordance with the present disclosure, Fig. 4 illustrates an exemplary method of personalizing the personalizable security document in accordance with the present disclosure, Fig. 5 shows a plan view of a personalized security document in accordance with the present disclosure when viewed from a first side in reflection, Fig. 6 shows.another plan view of the personalized security document when viewed from the first side in transmission, and Fig. 7 shows another plan view of the personalized security document when viewed from a second side. Detailed Description

[0009] The following is a detailed description of exemplary embodiments of the present disclosure. The exemplary embodiments described herein are intended to teach the principles of the present disclosure, enabling those of ordinary skill in the art to implement and use the present disclosure in many different environments and for many different applications. Therefore, the exemplary embodiments are not intended to be, and should not be considered as, a limiting description of the scope of protection. Rather, the scope of protection shall be defined by the appended claims.

[0010] The present disclosure is based at least in part on the realization that a secondary personalized feature in a security document plays a vital role in making the document more secure. While there are a large number of such secondary security features, for example, the Mirage security feature of HID, there are very few features that relate to personalizing a metallic layer such as a metallic foil. This is partially because a metallic foil or metal is difficult to engrave using a laser within a document.

[0011] It has been realized that a personalized metallic layer or foil can be used in combination with a further personalized layer to obtain a switch from a metallic portrait to a bi-colored or binary (non-metallic) personalized image when a mode of observation is changed. For example, an observer may perceive the personalized image as a metallic negative portrait when a security document is viewed in reflection, but the same personalized image may change to, for example, a bi-colored portrait that does not have a metallic appearance when the security document is viewed in transmission. This allows for obtaining a metallic switchable feature in a secondary window of a security document. It has been realized that this can be achieved by using a two-layer system consisting of a metallic foil or lens and an additional pigment layer which results in the opacity of the feature, and which also may have a further metallization effect.

[0012] It has also been realized that the security of the document can be further enhanced by combining the above-described metallic switch feature with one or more additional security features, for example, a watermark or an embossing in an outer surface of the security document. The interrelation of the plurality of security features can lock the security window of the security document in such a way that it is almost impossible to forge the same, as any attempt to forge one of the individual features will likely destroy one of the other elements.

[0013] It has also been realized that the personalization of the metallic layer may create an additional effect when the security document is viewed from the back side in transmission. This is because the personalized metallic foil results in what may be considered as a "personalized" or variable watermark, which can be seen, for example, when the security document is viewed from the back side in transmission. Namely, the unprocessed or only lightly processed portions of the metallic foil or layer result in that less light is transmitted through said portions when the security document is viewed from the back side in transmission, such that the unprocessed or only lightly processed portions appear darker than the processed portions. Additionally, the metal in the processed portions may be transferred to another layer of the substrate, resulting in a reduced opacity of the metallic layer in said portions. This, in combination with perhaps an additional watermark, may result in an additional feature that is both secure and can be easily observed by authorities.

[0014] Fig. 1 shows a plan view of an exemplary personalizable security document 10 in accordance with the present disclosure. As shown in Fig. 1, security document 10 includes a substrate 1, for example, having a substantially rectangular shape, but not limited to such a rectangular shape. Other shapes, for example, circular, elliptical, or polygonal shapes can also be used, depending on the application. In particular, as shown in Fig. 1, security document 10 is a personalizable security document, i.e., does not yet include an image, for example, a photograph or the like, of a person to which the document belongs. Such an image can be formed later, for example, in an image region provided on a first side S1 of substrate 1 in a known manner.

[0015] In addition, as shown in Fig.1, document 10 includes a security feature 3 formed in substrate 1, which is a window having, for example, a rectangular shape and in which one or more secure features may be provided. For example, as shown in Fig. 1, security feature 3 may include a metallic layer 4, in which a personalized image (for example, an inverse or negative image of the person to which the document belongs) can be laser engraved. As used herein, the expression "metallic layer", in particular in the context of a personalizable security document, is to be understood as an unstructured and unprocessed layer of metallic material, for example, having a constant thickness.

[0016] Fig. 2 shows a schematic cross-sectional view of personalizable security document 10. As shown in Fig. 2, personalizable security document 10 has substrate 1 having first side S1 and a second side S2 opposite to first side S1 in a thickness direction d of substrate 1. For example, substrate 1 may be formed by stacking a plurality of layers, for example, polycarbonate, TPU and / or PVC layers, and combining them in an appropriate manner, for example, by a lamination process or the like.

[0017] Security feature 3 is formed in substrate 1 and extends through at least part of substrate 1 along thickness direction d. In the example shown in Fig. 2, security feature 3 extends from an uppermost layer 20 to a bottom layer 24 of substrate 1. In some embodiments, at least the portion of each layer in which security feature 3 is formed is substantially transparent or at least semitransparent for visible light, such that, for example, metallic layer 4 is visible at least from first side S1 of security document 10 under white light.

[0018] Metallic layer 4 is configured to have a first personalized image 5a (see Fig. 5) laser-engraved in the same. In particular, metallic layer 4 exhibits a change in reflectivity upon irradiation with laser light. This will be described in more detail below. It will be appreciated that, generally, a metallic layer has a relatively high reflectivity when viewed, for example, under white light from first side S1. For example, the reflectivity of metallic layer 4 under white light may be between 30 % and 80 %, preferably between 40 % and 70 %.

[0019] In some embodiments, the irradiation of the laser light L onto portions of metallic layer 4 results in that the reflectivity changes, in particular, decreases. This may be because the properties of the metallic particles of metallic layer 4 are changed, or because the material in said portions is partially removed. In both cases, the processing with laser light can, for example, selectively reduce the reflectivity of metallic layer 4 in certain portions, such that a personalized image, for example, a negative of a portrait of the holder of security document 10, can be laser-engraved using appropriate laser parameters.

[0020] It will also be appreciated that metallic layer 4, during or after processing of the same by irradiating laser light, generally will transmit at least part of the irradiated laser light, such that the laser light can also reach lower regions or layers of substrate 1. As will be described in the following, this can be used in an advantageous manner to simultaneously engrave both personalized image 5a in metallic layer 4, as well as an additional personalized image in a layer that is disposed below metallic layer 4, to form a single (combined) personalized image.

[0021] To this end, as shown in Fig. 2, security feature 3 further includes a laser-engravable material 6 configured to have a second personalized image 5b (see Fig. 6) laser-engraved in the same. Laser-engravable material 6 exhibits a color-change effect upon irradiation with the laser light. Laser-engravable material 6 is embedded in substrate 1 below metallic layer 4 and overlaps the same when viewed along thickness direction d such that second personalized image 5b is formed together with first personalized image 5a upon irradiation of laser light onto metallic layer 4 from first side S1. This will be described in more detail below.

[0022] Metallic layer 4 may be any appropriately configured metallic layer, which can be engraved using laser light. For example, metallic layer 4 may include one or more of ZnS, Al, Cu, Sn, Fe or alloys of the same. In some embodiments, metallic layer 4 may consist of one or more of ZnS, Al, Cu, Sn, Fe or alloys of the same.

[0023] In some embodiments, metallic layer 4 is provided on a first layer 22 of the plurality of layers of substrate 1. For example, metallic layer 4 may be a metallic foil applied onto first layer 22, for example, by hot stamping prior to lamination of the plurality of layers to form substrate 1. An exemplary thickness of metallic layer 4 along thickness direction d may be between 1 µm and 100 µm, preferably between 1 µm and 50 µm, more preferably between 1 µm an 30 µm.

[0024] As shown in Fig. 2, laser-engravable material 6 may be formed as a material layer on one of the layers forming substrate 1 of security document 10. For example, an ink may be applied onto a surface of a layer 26 of substrate 1, for example, prior to laminating the different layers of substrate 1 to form security document 10. In other embodiments, laser-engravable material 6 may be formed in a different manner, either on a layer of substrate 1, or in a layer of the same. In any case, laser-engravable material 6 has a predetermined thickness in thickness direction d, for example, between 1 µm and 100 µm, preferably, between 1 µm and 50 µm, more preferably between 1 µm and 30 µm.

[0025] The material of laser-engravable material 6 has a property such that laser-engravable material 6 exhibits a color-change effect upon irradiation with laser light. As used herein, the "color-change effect upon irradiation with laser light" means that laser light that is irradiated onto laser-engravable material 6 changes at least one physical property of, for example, particles or pigments included in laser-engravable material 6 in a predetermined manner, for example, depending on the intensity of the laser light, and / or other laser parameters. One particular example is the ink that is used in the Mirage security feature of HID. In this technology, each pixel in laser-engraved personalized image 5b (see Fig. 6) has a defined color value, depending, for example, on a digital grayscale value of a grayscale image to be engraved. For example, a color value of blue corresponds to white in the digital grayscale image to be engraved, and a color value of gold corresponds to black in the digital grayscale image to be engraved. This means that, for example, a minimum or zero laser power results in that laser-engravable material 6 remains of an initial blue color, whereas increasing laser power results in a color change from the initial blue color towards a golden color at maximum laser power. In between the minimum and the maximum laser power, a color-change can be observed from blue to gold. In this manner, for example, a grayscale portrait of a holder of security document 10, for example, a negative or positive image, can be formed in a first surface 6a of laser-engravable material 6.

[0026] Here, it will be appreciated that the present application is not limited to the Mirage ink described above, and can be applied to any known laser-engravable material that exhibits a color-change effect when irradiated with laser light. However, it is important to note that the color-change effect as described herein is different from a change that is obtained when a physical structure of a material layer such as a transparent PVC layer or the like is modified by being burnt using a laser having a certain power. It will be appreciated that in such a manner a grayscale image can be formed, for example, in a top layer of substrate 1, however, such a formation of a grayscale image by burning of the material of the layer is not to be understood as exhibiting a color-change effect in accordance with the present disclosure. Accordingly, as used herein, a material that exhibits a color-change effect is to be considered a material which changes its color from a first, in particular, chromatic color (for example, blue) to a second, different color (for example, golden), and a change from, for example, colorless to gray or black due to burning of material with increasing laser power is not to be considered as a color-change effect. In some embodiments, laser-engravable material 6 includes metallic pigments, for example, one or more of Al, Ag, Au, Zn, Fe and Cu pigments.

[0027] Returning to Fig. 2, in the exemplary embodiment, laser-engravable material 6 is formed on second layer 26 of substrate 1. For example, the above-mentioned laser-engravable ink may be formed on a top surface of second layer 26, for example, by screen printing or the like. It will be appreciated, however, that in other embodiments laser-engravable material 6 may be formed on a bottom surface of first layer 22 or second layer 26, or on another layer of substrate 1. Additionally, first layer 22 is covered by one or more second layers 20, including, for example, a protective layer or the like. The stack of layers of substrate 1 is configured such that second personalized image 5b can be laser-engraved in laser-engravable material 6 from first side S1 together with first personalizable image 5a using an appropriately configured laser, as will be described in more detail below. It will be appreciated that, in particular, as second layer 26 is covered by one or more additional layers, said additional layers are at least partially transparent for the laser light, and the laser parameters are controlled such that the material of the additional layers is not visibly modified (i.e., burned) by the laser. Laser-engravable material 6 may be printed onto first layer 22 of second layer 26, for example, by screen printing, inkjet printing, offset printing, flexographic printing, or rotogravure.

[0028] As shown in Fig. 2, security feature 3 may further include an embossed pattern 11 formed in an outer surface of substrate 1 on first side S1. Embossed pattern 11 overlaps metallic layer 4 and laser-engravable material 6 and is visible when substrate 1 is viewed from first side S1 under white light. In other words, embossed pattern 4 is arranged such that it overlaps metallic layer 4 and laser-engravable material 6 when substrate 1 is viewed along thickness direction d. Embossed pattern 11 may be formed in the outer surface of substrate 1 in any known manner, for example, during a process of laminating the plurality of layers forming substrate 1.

[0029] In some embodiments, embossed pattern 11 is configured such that an appearance of the same changes when substrate 1 is viewed from first side S1 under white light (i.e., in reflection) at different observation angles. It will be readily appreciated that such a property of embossed pattern 11 can be obtained by appropriately configuring the microscopic structures of embossed pattern 11 (for example, depths of depressions, heights of peaks, distances between adjacent depressions / peaks, lattice constants of embossed structures such as grids, etc.), such that desired reflective, diffractive or refractive properties, which result in a change of the appearance of the observed pattern depending on the observation angle, are obtained. In this manner, embossed pattern 11 may have a first appearance when substrate 1 is viewed at a first observation angle from first side S1, and may have a second, different appearance when substrate 1 is viewed at a second, different observation angle from the same side under white light.

[0030] It should be appreciated that the change in appearance may have any desired configuration, for example, may include at least one of a change in color, a change in opacity, a change in reflectivity, or a change in shape (i.e., visible area) of embossed pattern 11. Typical sizes of the structures forming embossed pattern 11 are, for example, between 5 µm and 50 µm, preferably, between 10 µm and 30 µm.

[0031] As also shown in Fig. 2, security feature 3 may further include a watermark 7 provided in substrate 1 between laser-engravable material 6 and second side S2. For example, watermark 7 may be applied on or in bottom layer 24 of substrate 1, for example, by printing watermark 7 on a top surface of bottom layer 24, for example, by offset printing, flexographic printing, and the like. Watermark 7 is aligned with metallic layer 4 (and therefore also laser-engravable material 6), and watermark 7 is visible when substrate 1 is viewed from first side S1 against white light (i.e., in transmission). This is shown, for example, in Fig. 6. The use of watermarks such as watermark 7 is well-known, such that a detailed description will be omitted. However, what is important is that watermark 7 is aligned with metallic layer 4 and laser-engravable material 6, resulting in a combined feature that is visible when security document 10 is viewed from first side S1 in transmission.

[0032] Fig. 2 shows that second layer 26 is present between first layer 22 and bottom layer 24 of substrate 1, on or in which watermark 7 is provided. However, it will be appreciated that in other embodiments one or more intermediate layers may be provided between second layer 26 and bottom layer 24, if desired. Likewise, it will be appreciated that watermark 7 does not need to be formed on bottom layer 24, but can also be formed in any intermediate layers between bottom layer 24 and first layer 22, if desired.

[0033] A distance between metallic layer 4 and laser-engravable material 6 in thickness direction d may be between 50 µm and 800 µm, preferably between 50 µm and 200 µm. As such, a total thickness of the combination of metallic layer 4 and laser-engravable material 6 along thickness direction d may be between 100 µm and 900 µm, preferably between 200 µm and 250 µm.

[0034] Fig. 3 shows individual layers 22, 26 and 24 of substrate 1 in plan view. In the exemplary embodiment shown in Fig. 3, each of metallic layer 4, laser-engravable material 6 and watermark 7 of security feature 3 is provided on a top surface of the respective layers 22, 26, 24. However, as mentioned above, other configurations, in which some features are provided on a bottom surface of the respective layers of substrate 1 are also possible. Additionally, it should be appreciated that the present disclosure is not limited to security documents with substrates such as substrate 1 including the plurality of layers 20-24. In other words, it is sufficient that metallic layer 4 and laser-engravable material 6 are embedded in substrate 1 such that they overlap with each other, and can be laser-engraved from first side S1 or second side S2 to simultaneously form personalized images 5a and 5b in the manner that will be described in more detail in the following.

[0035] For example, as shown in Fig. 4, which shows a cross-section of substrate 1 during personalization of security document 10, laser light L may be irradiated onto metallic layer 4 from first side S1 to laser-engrave a personalized image in metallic layer 4 and laser-engravable material 6. In particular, during formation of, for example, first personalized image 5a and second personalized image 5b, which together form a single (combined) personalized image that has different appearances when viewed under different illumination or observation modes, laser parameters such as a laser wavelength, a laser speed, and a laser repetition rate may be varied in order to form first personalized image 5a and second personalized image 5b. Here, in particular, the laser parameters are chosen such that part of the laser light that hits metallic layer 4 is transmitted through metallic layer 4 and layer 22 of substrate 1 to reach laser-engravable material 6. In this manner, at the same time as forming first personalized image 5a in metallic layer 4, similar or identical second personalized image 5b may be formed in the underlying laser-engravable material 6. For example, a negative portrait of a holder of security document 10 may be formed in a known manner by varying the laser parameters. In particular, a laser wavelength of between 530 nm and 1060 nm may be used, a laser speed between 100 mm / s and 4000 mm / s may be used, and a laser repetition rate of between 50 kHz and 100 kHz may be used. The laser used to engrave the images may be focused at an appropriate position along the depth direction, for example, on metallic layer 4, on laser-engravable material 6, or an intermediate position between the same.

[0036] As already mentioned above, the varying laser parameters may result in varying changes in the reflectivity of metallic layer 4. Some regions may retain the original, relatively high reflectivity, whereas regions that are processed more may experience a decrease in the reflectivity. In this manner, personalized image features can be engraved in metallic layer 4. For example, the portions of the image to be engraved that are relatively light may correspond to the portions of metallic layer 4 that are heavily processed, whereas the portions of the image to be engraved that are relatively dark may correspond to the portions of metallic layer 4 which are not processed, or only lightly processed. Due to this processing, different amounts of laser light L reach the underlying laser-engravable material layer 6. Accordingly, the portions of laser-engravable material 6 that correspond to the portions of metallic layer 4 that are heavily processed are also processed more heavily than the other portions of laser-engravable material layer 6. Therefore, in such a manner, the same or similar, for example, negative personalized image can be engraved both in metallic layer 4 and in laser-engravable material 6 at the same time.

[0037] Here, the laser parameters are selected such that, due to the presence of metallic layer 4, the amount of laser light that reaches laser-engravable material 6 is reduced, such that laser-engravable material layer 6 and layer 26 of substrate 1 are not damaged by the laser light. On the other hand, if, for example, the same laser light was directly irradiated onto laser-engravable material 6, the same would be damaged or even destroyed. Accordingly, the knowledge of the appropriate laser parameters to be used for the combination of metallic layer 4 and laser-engravable material 6 is key to be able to successfully form the personalized images. This makes it very difficult to forge a personalized security document 10 having the above-described combination of two personalized images.

[0038] Fig. 5 shows an exemplary plan view of personalized security document 10 when viewed from first side S1 under white light, i.e., in reflection. As shown in Fig. 5, in addition to a primary personalized image 2, which may show a portrait of a holder of security document 10, a secondary personalized image 5a, which has been laser-engraved in metallic layer 4, can be observed. In particular, different image features of first personalized image 5a have different reflectivity due to the laser-engraving. As such, a metallic secondary portrait can be observed as first personalized image 5a. As the colored image features of second personalized image 5b are below the image features of first personalized image 5a, and first personalized image 5a is highly reflective, the image features of second personalized image 5b generally will not be seen when security document 10 is viewed from first side S1 under white light. However, if, for example, the regions of metallic layer 4 surrounding the secondary portrait are heavily processed using laser light L, the reflectivity in said regions may be very low or even vanish. Likewise, laser-engravable material 6 in said regions will also have been processed considerably. If, for example, laser-engravable material 6 includes metallic pigments, said metallic pigments may then be visible from first side S1 under white light, and may contribute to the overall metallic appearance of security feature 3.

[0039] When the mode of observation is changed, for example, to view security document 10 from first side S1 in transmission, i.e., against white light, the observed nature of the secondary portrait will change. In particular, the metallic effect will disappear, and instead the image features of, in particular, second personalized image 5b will appear in an essentially bi-color or binary non-metallic image, as shown in Fig. 6. Here, it should be noted that images 5a and 5b generally form a combined personalized image that is visible in both observation modes. However, to illustrate the effect of switching from a metallic to a non-metallic image, image 5a is illustrated in Fig. 5, whereas image 5b is illustrated in Figs. 6 and 7. Additionally, watermark 7 will be visible in a known manner. The fact that, in addition to watermark 7, also the personalized image is visible is due to the fact that the portions of metallic layer 4, which were not processed, or only lightly processed by laser light L remain highly reflective, such that less light is transmitted through said portions than through the processed portions of metallic layer 4 and laser-engravable material 6. This essentially results in the creation of what may be considered as a "personalized watermark" that resembles first and second personalized images 5a, 5b. The properties of laser-engravable material 6 may impart a certain background color to the image that can be seen when security document 10 is viewed in transmission. For example, in the Mirage security feature of HID, the unprocessed laser-engravable material 6 has a blue color, such that, when security document 10 is viewed in transmission, this may result in a blue-tone background, against which the darker image features in first and second personalized images 5a, 5b can be recognized.

[0040] Fig. 7 shows a plan view of security document 10 when viewed from second side S2. Here, in reflection, it will be evident that, generally, only watermark 7 can be observed, if present, due to the opacity and uniform color of the lower surface of laser-engravable material 6.

[0041] On the other hand, if security document 10 is viewed from second side S2 in transmission, in addition to watermark 7, if present, again the secondary portrait, i.e., personalized images 5a, 5b can be observed. This is again due to the creation of what can be considered as a "variable" or "personalized" watermark due to the processing of, in particular, metallic layer 4. As described above, for example, the unprocessed portions remain highly reflective, such that less light is transmitted through metallic layer 4 and laser-engravable material 6, resulting in that the image features in first and second personalized images 5a, 5b can be recognized.Industrial applicability

[0042] With the above-described configurations, a personalizable security document 10 that combines two or more secure features, in particular, a metallic personalized image, which can be observed from first side S1 under white light, and a non-metallic same or similar personalized image, which can be observed from first side S1 in transmission, can be obtained. As appropriate laser parameters have to be used to be able to form both of said personalized images without destroying one or both of the materials to be engraved, it becomes very difficult to forge the corresponding security feature 3,

[0043] After personalizable security document 10 has been manufactured, the same may be supplied to customers, where personalization of security document 10 can be performed in a known manner.

[0044] In particular, as previously mentioned, the personalization of security document 10 can be performed by providing personalizable security document 10 in accordance with the present disclosure, and simultaneously laser-engraving first personalized image 5a and second personalized image 5b from first side S1 in metallic layer 4 and laser-engravable material 6, respectively, by varying one or more laser parameters, wherein the laser parameters may include one or more of a laser wavelength between 530 nm and 1060 nm, a laser speed between 100 mm / s and 4000 mm / s, and a laser repetition rate between 50 kHz and 100 kHz. Additionally, a primary personalized image 2 can also be formed, for example, in an upper layer of substrate 1 in a known manner.

[0045] It will be appreciated that the foregoing description provides examples of the disclosed systems and methods. However, it is contemplated that other implementations of the disclosure may differ in detail from the foregoing examples. All references to the disclosure or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the general disclosure.

[0046] Recitation of ranges of values herein are merely intended to serve as a shorthand method for referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All method steps described herein can be performed in any suitable order, unless otherwise indicated or clearly contradicted by the context.

[0047] Although the preferred embodiments of the present disclosure have been described herein, improvements and modifications may be incorporated without departing from the scope of the following claims.

Claims

1. A personalizable security document (10) comprising: a substrate (1) having a first side (S1) and a second side (S2) opposite to the first side in a thickness direction (d) of the substrate (1); and a security feature (3) formed in the substrate (1) and extending through at least part of the substrate along the thickness direction (d), wherein the security feature (3) includes: a metallic layer (4) configured to have a first personalized image (5a) laser engraved in the same, the metallic layer (4) exhibiting a change in reflectivity upon irradiation with laser light (L), the metallic layer (4) being visible when the substrate (1) is viewed from the first side (S1) under white light; and a laser-engravable material (6) configured to have a second personalized image (5b) laser engraved in the same, the laser-engravable material (6) exhibiting a color-change effect upon irradiation with the laser light (L), the laser-engravable material (6) being embedded in the substrate (1) below the metallic layer (4) and overlapping the same at least in part when viewed along the thickness direction (d) such that the second personalized image (5b) is formed together with the first personalized image (5a) upon the irradiation of the laser light onto the metallic layer (4) from the first side (S1).

2. The security document of claim 1, wherein the laser-engravable material (6) includes metallic pigments, for example, one or more of Al, Ag, Au, Zn, Fe and Cu pigments.

3. The security document of claim 1 or 2, wherein the metallic layer (4) includes one or more of ZnS, Al, Cu, Sn, Fe.

4. The security document of any one of claims 1 to 3, wherein the substrate (1) includes a plurality of layers, for example, polycarbonate layers, the metallic layer (4) being provided on a first layer (22) of the plurality of layers.

5. The security document of claim 4, wherein the metallic layer (4) is a metallic foil applied onto the first layer (22), for example, by hot stamping.

6. The security document of claim 4 or 5, wherein the laser-engravable material (6) is provided on a second layer (26) of the plurality of layers arranged below the first layer (22).

7. The security document of claim 4 or 5, wherein the metallic layer (4) is provided on a first surface (22a) of the first layer (22), and the laser-engravable material (6) is provided on an opposite second surface (22b) of the first layer (22).

8. The security document of claim 6 or 7, wherein the laser-engravable material (6) is printed onto the first layer (22) or the second layer (26), for example, by screen printing, inkjet printing, offset printing, flexographic printing, or rotogravure.

9. The security document of any one of claims 1 to 8, wherein the security feature (3) includes a watermark (7) provided in the substrate (1) between the laser-engravable material (6) and the second side (S2), the watermark (7) overlapping the metallic layer (4) and the laser-engravable material (6) when viewed along the thickness direction (d), the watermark being visible when the substrate (1) is viewed from the first side (S 1) against white light.

10. The security document of any one of claims 1 to 9, wherein the security feature (3) includes an embossed pattern (11) formed in an outer surface of the substrate (1) on the first side (S1), the embossed pattern overlapping the metallic layer (4) and the laser-engravable material (6) and being visible when the substrate (1) is viewed from the first side (S1) under white light.

11. The security document of claim 10, wherein an appearance of the embossed pattern (11) changes when the substrate (1) is viewed from the first side (S1) under white light at different observation angles, wherein the change in appearance includes at least one of a change in color, a change in opacity, a change in reflectivity, or a change in shape of the embossed pattern (11).

12. The security document of any one of claims 1 to 11, wherein a thickness of each of the metallic layer (4) and the laser-engravable material (6) along the thickness direction (d) is between 1 µm and 100 µm, preferably between 1 µm and 50 µm, more preferably between 1 µm and 30 µm.

13. The security document of any one of claims 1 to 12, wherein a distance between the metallic layer (4) and the laser-engravable material (6) in the thickness direction (d) is between 50 µm and 800 µm, preferably between 50 µm and 200 µm.

14. A method of personalizing a security document (10), comprising: providing a personalizable security document (10) in accordance with any one of claims 1 to 13; and simultaneously laser engraving the first personalized image (5a) and the second personalized image (5b) from the first side (S1) in the metallic layer (4) and the laser-engravable material (6), respectively, by varying one or more laser parameters.

15. The method of claim 14, wherein the laser parameters include one or more of a laser wavelength between 530 nm and 1060 nm, a laser speed between 100 mm / s and 4000 mm / s, and a laser repetition rate between 50 kHz and 100 kHz.

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